Sample records for eddy correlation technique

  1. Eddy current technique for predicting burst pressure

    DOEpatents

    Petri, Mark C.; Kupperman, David S.; Morman, James A.; Reifman, Jaques; Wei, Thomas Y. C.

    2003-01-01

    A signal processing technique which correlates eddy current inspection data from a tube having a critical tubing defect with a range of predicted burst pressures for the tube is provided. The method can directly correlate the raw eddy current inspection data representing the critical tubing defect with the range of burst pressures using a regression technique, preferably an artificial neural network. Alternatively, the technique deconvolves the raw eddy current inspection data into a set of undistorted signals, each of which represents a separate defect of the tube. The undistorted defect signal which represents the critical tubing defect is related to a range of burst pressures utilizing a regression technique.

  2. Effects of Eddy Viscosity on Time Correlations in Large Eddy Simulation

    NASA Technical Reports Server (NTRS)

    He, Guowei; Rubinstein, R.; Wang, Lian-Ping; Bushnell, Dennis M. (Technical Monitor)

    2001-01-01

    Subgrid-scale (SGS) models for large. eddy simulation (LES) have generally been evaluated by their ability to predict single-time statistics of turbulent flows such as kinetic energy and Reynolds stresses. Recent application- of large eddy simulation to the evaluation of sound sources in turbulent flows, a problem in which time, correlations determine the frequency distribution of acoustic radiation, suggest that subgrid models should also be evaluated by their ability to predict time correlations in turbulent flows. This paper compares the two-point, two-time Eulerian velocity correlation evaluated from direct numerical simulation (DNS) with that evaluated from LES, using a spectral eddy viscosity, for isotropic homogeneous turbulence. It is found that the LES fields are too coherent, in the sense that their time correlations decay more slowly than the corresponding time. correlations in the DNS fields. This observation is confirmed by theoretical estimates of time correlations using the Taylor expansion technique. Tile reason for the slower decay is that the eddy viscosity does not include the random backscatter, which decorrelates fluid motion at large scales. An effective eddy viscosity associated with time correlations is formulated, to which the eddy viscosity associated with energy transfer is a leading order approximation.

  3. Eddy Correlation Flux Measurement System (ECOR) Handbook

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cook, DR

    2011-01-31

    The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration.

  4. DEVELOPMENT OF TECHNIQUES FOR EDDY-CORRELATION MEASUREMENTS OF NON-METHANE VOLATILE ORGANIC COMPOUND FLUXED IN THE ATMOSPHERE

    EPA Science Inventory

    An analytical technique for the measurement of the exchange (flux) of trace gases between the earth's surface and the atmosphere will be developed. Measurements will rely on the eddy correlation method (ECM). Target compounds are biogenically and anthropogenically emitted v...

  5. Assessment of benthic flux of dissolved organic carbon in wetland and estuarine sediments using the eddy-correlation technique

    NASA Astrophysics Data System (ADS)

    Swett, M. P.; Amirbahman, A.; Boss, E.

    2009-12-01

    Wetland and estuarine sediments release significant amounts of dissolved organic carbon (DOC) due to high levels of microbial activity, particularly sulfate reduction. Changes in climate and hydrologic conditions have a potential to alter DOC release from these systems as well. This is a concern, as high levels of DOC can lead to mobilization of toxic metals and organics in natural waters. In addition, source waters high in DOC produce undesirable disinfection byproducts in water treatment. Various in situ methods, such as peepers and sediment core centrifugation, exist to quantify vertical benthic fluxes of DOC and other dissolved species from the sediment-water interface (SWI). These techniques, however, are intrusive and involve disturbance of the sediment environment. Eddy-correlation allows for real-time, non-intrusive, in situ flux measurement of important analytes, such as O2 and DOC. An Acoustic Doppler Velocimeter (ADV) is used to obtain three-dimensional fluid velocity measurements. The eddy-correlation technique employs the mathematical separation of fluid velocity into mean velocity and fluctuating velocity components, with the latter representing turbulent eddy velocity. DOC concentrations are measured using a colored dissolved organic matter (CDOM) fluorometer, and instantaneous vertical flux is determined from the correlated data. This study assesses DOC flux at three project sites: a beaver pond in the Lower Penobscot Watershed, Maine; a mudflat in Penobscot River, Maine; and a mudflat in Great Bay, New Hampshire. Eddy flux values are compared with results obtained using peepers and centrifugation, as well as vertical profiling.

  6. Water Velocity as a Driver of Stream Metabolism: a Parallel Application of the Open Water and Eddy Correlation Techniques

    NASA Astrophysics Data System (ADS)

    Koopmans, D.; Berg, P.

    2013-12-01

    Inland waters respire or store a large portion of net terrestrial ecosystem production. As a result their metabolism is significant to the global carbon budget. The proximal drivers of aquatic respiration are organic matter availability, temperature, nutrients, and water velocity. Among these water velocity may be the least quantified. A partial explanation is that the footprint of the open water technique is typically hundreds of meters of river length, while the effect of a change in velocity may be specific to a local benthic environment, e.g., a riffle. With the eddy correlation technique oxygen flux is calculated from the turbulent fluctuation of vertical velocity and the oxygen concentration at a point in the water column. The footprint of the technique scales with the height of the point of measurement allowing an investigation of the in situ oxygen flux at the scale of a riffle. The combination of techniques, then, can be used to investigate the coupling of hydrodynamic conditions and benthic environments in driving aquatic ecosystem metabolism. This parallel approach was applied seasonally to examine the drivers of metabolism in a nutrient-rich, sand-bed coastal stream on the Eastern Shore of Virginia. An ecosystem-scale oxygen flux was calculated with the open water technique while pool-, run-, riffle-, and freshwater tidal-scale oxygen fluxes were calculated with the eddy correlation technique. At the ecosystem scale the stream bed functioned as an effective biocatalytic filter with an average annual net oxygen consumption of 300 mmol m^-2 d^-1. Prior to a stage-discharge shift water velocity explained 90% of the variance in ecosystem respiration (n = 63 days). After the stage-discharge shift water velocity explained 96 % of it (n = 40 days). Hyporheic exchange supported respiration in this system, contributing to its close correlation with water velocity. Among the physically similar benthic environments of the run, riffle, and freshwater tidal sites

  7. Relating chamber measurements to eddy correlation measurements of methane flux

    Treesearch

    R.J. Clement; S.B. Verma; E.S. Verry

    1995-01-01

    Methane fluxes were measured using eddy correlation and chamber techniques during 1991 and 1997 at a peatland in north central Minnesota. Comparisons of the two techniques were made using averages of methane flux data available during 1-week periods. The seasonal patterns of fluxes measured by the two techniques compared well. Chamber flux, in 1991, was about 1.8 mg m...

  8. Eddy correlation measurements of submarine groundwater discharge

    USGS Publications Warehouse

    Crusius, John; Berg, P.; Koopmans, D.J.; Erban, L.

    2008-01-01

    This paper presents a new, non-invasive means of quantifying groundwater discharge into marine waters using an eddy correlation approach. The method takes advantage of the fact that, in virtually all aquatic environments, the dominant mode of vertical transport near the sediment–water interface is turbulent mixing. The technique thus relies on measuring simultaneously the fluctuating vertical velocity using an acoustic Doppler velocimeter and the fluctuating salinity and/or temperature using rapid-response conductivity and/or temperature sensors. The measurements are typically done at a height of 5–15 cm above the sediment surface, at a frequency of 16 to 64 Hz, and for a period of 15 to 60 min. If the groundwater salinity and/or temperature differ from that of the water column, the groundwater specific discharge (cm d− 1) can be quantified from either a heat or salt balance. Groundwater discharge was estimated with this new approach in Salt Pond, a small estuary on Cape Cod (MA, USA). Estimates agreed well with previous estimates of discharge measured using seepage meters and 222Rn as a tracer. The eddy correlation technique has several desirable characteristics: 1) discharge is quantified under in-situ hydrodynamic conditions; 2) salinity and temperature can serve as two semi-independent tracers of discharge; 3) discharge can be quantified at high temporal resolution, and 4) long-term records of discharge may be possible, due to the low power requirements of the instrumentation.

  9. Non-Destructive Techniques Based on Eddy Current Testing

    PubMed Central

    García-Martín, Javier; Gómez-Gil, Jaime; Vázquez-Sánchez, Ernesto

    2011-01-01

    Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future. PMID:22163754

  10. Non-destructive techniques based on eddy current testing.

    PubMed

    García-Martín, Javier; Gómez-Gil, Jaime; Vázquez-Sánchez, Ernesto

    2011-01-01

    Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future.

  11. Eddy Correlation Flux Measurement System Handbook

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cook, D. R.

    2016-01-01

    The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration. The instruments used are: • a fast-response, three-dimensional (3D) wind sensor (sonic anemometer) to obtain the orthogonal wind componentsmore » and the speed of sound (SOS) (used to derive the air temperature) • an open-path infrared gas analyzer (IRGA) to obtain the water vapor density and the CO2 concentration, and • an open-path infrared gas analyzer (IRGA) to obtain methane density and methane flux at one SGP EF and at the NSA CF. The ECOR systems are deployed at the locations where other methods for surface flux measurements (e.g., energy balance Bowen ratio [EBBR] systems) are difficult to employ, primarily at the north edge of a field of crops. A Surface Energy Balance System (SEBS) has been installed collocated with each deployed ECOR system in SGP, NSA, Tropical Western Pacific (TWP), ARM Mobile Facility 1 (AMF1), and ARM Mobile Facility 2 (AMF2). The surface energy balance system consists of upwelling and downwelling solar and infrared radiometers within one net radiometer, a wetness sensor, and soil measurements. The SEBS measurements allow the comparison of ECOR sensible and latent heat fluxes with the energy balance determined from the SEBS and provide information on wetting of the sensors for data quality purposes. The SEBS at one SGP and one NSA site also support upwelling and downwelling PAR measurements to qualify those two locations as Ameriflux sites.« less

  12. Geohydrology and evapotranspiration at Franklin Lake playa, Inyo County, California; with a section on estimating evapotranspiration using the energy-budget eddy-correlation technique

    USGS Publications Warehouse

    Czarnecki, John B.; Stannard, David I.

    1997-01-01

    Franklin Lake playa is one of the principal discharge areas of the ground-water-flow system associated with Yucca Mountain, Nevada, the potential site of a high-level nuclear-waste repository. By using the energy-budget eddy-correlation technique, measurements made between June 1983 and April 1984 to estimate evapotranspiration were found to range from 0.1 centimeter per day during winter months to about 0.3 centimeter per day during summer months; the annual average was 0.16 centimeter per day. These estimates were compared with evapotranspiration estimates calculated from six other methods.

  13. Technique for temperature compensation of eddy-current proximity probes

    NASA Technical Reports Server (NTRS)

    Masters, Robert M.

    1989-01-01

    Eddy-current proximity probes are used in turbomachinery evaluation testing and operation to measure distances, primarily vibration, deflection, or displacment of shafts, bearings and seals. Measurements of steady-state conditions made with standard eddy-current proximity probes are susceptible to error caused by temperature variations during normal operation of the component under investigation. Errors resulting from temperature effects for the specific probes used in this study were approximately 1.016 x 10 to the -3 mm/deg C over the temperature range of -252 to 100 C. This report examines temperature caused changes on the eddy-current proximity probe measurement system, establishes their origin, and discusses what may be done to minimize their effect on the output signal. In addition, recommendations are made for the installation and operation of the electronic components associated with an eddy-current proximity probe. Several techniques are described that provide active on-line error compensation for over 95 percent of the temperature effects.

  14. Tests of a robust eddy correlation system for sensible heat flux

    NASA Astrophysics Data System (ADS)

    Blanford, J. H.; Gay, L. W.

    1992-03-01

    Sensible heat flux estimates from a simple, one-propeller eddy correlation system (OPEC) were compared with those from a sonic anemometer eddy correlation system (SEC). In accordance with similarity theory, the performance of the OPEC system improved with increasing height of the sensor above the surface. Flux totals from the two systems at sites with adequate fetch were in excellent agreement after frequency response corrections were applied. The propeller system appears suitable for long periods of unattended measurement. The sensible heat flux measurements can be combined with net radiation and soil heat flux measurements to estimate latent heat as a residual in the surface energy balance.

  15. Removing Wave Artifacts from Eddy Correlation Data

    NASA Astrophysics Data System (ADS)

    Neumann, Andreas; Brand, Andreas

    2017-04-01

    on the example of the North-Frisian Wadden Sea we will discuss the potentials and limits of this method. References: Berg, P., H. Roy, F. Janssen, V. Meyer, B. Jorgensen, M. Huettel, and D. de Beer (2003), Oxygen uptake by aquatic sediments measured with a novel non-invasive eddy-correlation technique, Marine Ecology-Progress Series, 261, 75-83, doi:10.3354/meps261075. Bricker, J. D., and S. G. Monismith (2007), Spectral wave turbulence decomposition, J. Atmos. Oceanic Technol., 24(8), 1479-1487, doi:10.1175/JTECH2066.1.

  16. Eddy Current Rail Inspection Using AC Bridge Techniques.

    PubMed

    Liu, Ze; Koffman, Andrew D; Waltrip, Bryan C; Wang, Yicheng

    2013-01-01

    AC bridge techniques commonly used for precision impedance measurements have been adapted to develop an eddy current sensor for rail defect detection. By using two detection coils instead of just one as in a conventional sensor, we can balance out the large baseline signals corresponding to a normal rail. We have significantly enhanced the detection sensitivity of the eddy current method by detecting and demodulating the differential signal of the two coils induced by rail defects, using a digital lock-in amplifier algorithm. We have also explored compensating for the lift-off effect of the eddy current sensor due to vibrations by using the summing signal of the detection coils to measure the lift-off distance. The dominant component of the summing signal is a constant resulting from direct coupling from the excitation coil, which can be experimentally determined. The remainder of the summing signal, which decreases as the lift-off distance increases, is induced by the secondary eddy current. This dependence on the lift-off distance is used to calibrate the differential signal, allowing for a more accurate characterization of the defects. Simulated experiments on a sample rail have been performed using a computer controlled X-Y moving table with the X-axis mimicking the train's motion and the Y-axis mimicking the train's vibrational bumping. Experimental results demonstrate the effectiveness of the new detection method.

  17. Using the Cross-Correlation Function to Evaluate the Quality of Eddy-Covariance Data

    NASA Astrophysics Data System (ADS)

    Qi, Yongfeng; Shang, Xiaodong; Chen, Guiying; Gao, Zhiqiu; Bi, Xueyan

    2015-11-01

    A cross-correlation test is proposed for evaluating the quality of 30-min eddy-covariance data. Cross-correlation as a function of time lag is computed for vertical velocity paired with temperature, humidity, and carbon dioxide concentration. High quality data have a dominant peak at zero time lag and approach zero within a time lag of 20 s. Poor quality data have erratic cross-correlation functions, which indicates that the eddy flux may no longer represent the energy and mass exchange between the atmospheric surface layer and the canopy, and such data should be rejected in post-data analyses. Eddy-covariance data over grassland in July 2004 are used to evaluate the proposed test. The results show that 17, 29, and 36 % of the available data should be rejected because of poor quality measurements of sensible heat, latent heat, and CO2 fluxes, respectively. The rejected data mainly occurred on calm nights and day/night transitions when the atmospheric surface layer became stable or neutrally stratified. We found no friction velocity (u_*) threshold below which all data should be rejected, a test that many other studies have implemented for rejecting questionable data. We instead found that some data with low u_* were reliable, whereas other data with higher u_* were not. The poor quality measurements collected under less than ideal conditions were replaced by using the mean diurnal variation gap-filling method. The correction for poor quality data shifted the daily average CO2 flux by +0.34 g C m^{-2} day^{-1}. After applying the quality-control test, the eddy CO2 fluxes did not display a clear dependence on u_*. The results suggest that the cross-correlation test is a potentially valuable step in evaluating the quality of eddy-covariance data.

  18. USE OF RELAXED EDDY ACCUMULATION TO MEASURE BIOSPHERE-ATMOSPHERE EXCHANGE OF ISOPRENE AND OTHER BIOLOGICAL TRACE GASES

    EPA Science Inventory

    The micrometeorological flux measurement technique known as relaxed eddy accumulation (REA) holds promise as a powerful new tool for ecologists. The more popular eddy covariance (eddy correlation) technique requires the use of sensors that can respond at fast rates (10 Hz), and t...

  19. Correlation of eddy current responses between fatigue cracks and electrical-discharge-machining notches

    NASA Astrophysics Data System (ADS)

    Seo, Sukho; Choi, Gyudong; Eom, Tae Jhoun; Lee, Bokwon; Lee, Soo Yeol

    2017-07-01

    The eddy current responses of Electrical Discharge Machining (EDM) notches and fatigue cracks are directly compared to verify the reliability of eddy current inspection. The fatigue crack growth tests using a constant load range control mode were conducted to obtain a variety of edge crack sizes, ranging from 0.9 to 6.6 mm for Al alloy and from 0.1 to 3 mm for Ti alloy. EDM notch specimens of Al and Ti alloys were accordingly prepared in lengths similar to that of the fatigued specimen. The crack length was determined by optical microscope and scanning electron microscope. The eddy current responses between the EDM and fatigued specimens with varying notch/crack length were examined using probe sensors at (100-500) kHz and (1-2) MHz for Al and Ti alloys, respectively. The results show a significant difference in the eddy current signal between the two specimens, based on the correlation between the eddy current response and notch/crack length. This suggests that eddy current inspection using the EDM reference specimen is inaccurate in determining the precise crack size, unless the eddy current response data base is obtained from a fatigue-cracked specimen.

  20. Eddy current techniques for super duplex stainless steel characterization

    NASA Astrophysics Data System (ADS)

    Camerini, C.; Sacramento, R.; Areiza, M. C.; Rocha, A.; Santos, R.; Rebello, J. M.; Pereira, G.

    2015-08-01

    Super duplex stainless steel (SDSS) is a two-phase material where the microstructure consists of grains of ferrite (δ) and austenite (γ). SDSS exhibit an attractive combination of properties, such as: strength, toughness and stress corrosion cracking resistance. Nevertheless, SDSS attain these properties after a controlled solution heat treatment, leading to a similar volumetric fraction of δ and γ. Any further heat treatment, welding operation for example, can change the balance of the original phases, or may also lead to precipitation of a deleterious phase, such as sigma (σ). For these situations, the material corrosion resistance is severely impaired. In the present study, several SDSS samples with low σ phase content and non-balanced microstructure were intentionally obtained by thermally treating SDSS specimens. Electromagnetic techniques, conventional Eddy Current Testing (ECT) and Saturated Low Frequency Eddy Current (SLOFEC), were employed to characterize the SDSS samples. The results showed that ECT and SLOFEC are reliable techniques to evaluate σ phase presence in SDSS and can provide an estimation of the δ content.

  1. Seagrass metabolism across a productivity gradient using the eddy covariance, Eulerian control volume, and biomass addition techniques

    NASA Astrophysics Data System (ADS)

    Long, Matthew H.; Berg, Peter; Falter, James L.

    2015-05-01

    The net ecosystem metabolism of the seagrass Thalassia testudinum was studied across a nutrient and productivity gradient in Florida Bay, Florida, using the Eulerian control volume, eddy covariance, and biomass addition techniques. In situ oxygen fluxes were determined by a triangular Eulerian control volume with sides 250 m long and by eddy covariance instrumentation at its center. The biomass addition technique evaluated the aboveground seagrass productivity through the net biomass added. The spatial and temporal resolutions, accuracies, and applicability of each method were compared. The eddy covariance technique better resolved the short-term flux rates and the productivity gradient across the bay, which was consistent with the long-term measurements from the biomass addition technique. The net primary production rates from the biomass addition technique, which were expected to show greater autotrophy due to the exclusion of sediment metabolism and belowground production, were 71, 53, and 30 mmol carbon m-2 d-1 at 3 sites across the bay. The net ecosystem metabolism was 35, 25, and 11 mmol oxygen m-2 d-1 from the eddy covariance technique and 10, -103, and 14 mmol oxygen m-2 d-1 from the Eulerian control volume across the same sites, respectively. The low-flow conditions in the shallow bays allowed for periodic stratification and long residence times within the Eulerian control volume that likely reduced its precision. Overall, the eddy covariance technique had the highest temporal resolution while producing accurate long-term flux rates that surpassed the capabilities of the biomass addition and Eulerian control volume techniques in these shallow coastal bays.

  2. Immersed transient eddy current flow metering: a calibration-free velocity measurement technique for liquid metals

    NASA Astrophysics Data System (ADS)

    Krauter, N.; Stefani, F.

    2017-10-01

    Eddy current flow meters are widely used for measuring the flow velocity of electrically conducting fluids. Since the flow induced perturbations of a magnetic field depend both on the geometry and the conductivity of the fluid, extensive calibration is needed to get accurate results. Transient eddy current flow metering has been developed to overcome this problem. It relies on tracking the position of an impressed eddy current system that is moving with the same velocity as the conductive fluid. We present an immersed version of this measurement technique and demonstrate its viability by numerical simulations and a first experimental validation.

  3. Application of Eddy Current Techniques for Orbiter Reinforced Carbon-Carbon Structural Health Monitoring

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz; Simpson, John

    2005-01-01

    The development and application of advanced nondestructive evaluation techniques for the Reinforced Carbon-Carbon (RCC) components of the Space Shuttle Orbiter Leading Edge Structural Subsystem (LESS) was identified as a crucial step toward returning the shuttle fleet to service. In order to help meet this requirement, eddy current techniques have been developed for application to RCC components. Eddy current technology has been found to be particularly useful for measuring the protective coating thickness over the reinforced carbon-carbon and for the identification of near surface cracking and voids in the RCC matrix. Testing has been performed on as manufactured and flown RCC components with both actual and fabricated defects representing impact and oxidation damage. Encouraging initial results have led to the development of two separate eddy current systems for in-situ RCC inspections in the orbiter processing facility. Each of these systems has undergone blind validation testing on a full scale leading edge panel, and recently transitioned to Kennedy Space Center to be applied as a part of a comprehensive RCC inspection strategy to be performed in the orbiter processing facility after each shuttle flight.

  4. Detection of cracks beneath rivet heads via pulsed eddy current technique

    NASA Astrophysics Data System (ADS)

    Giguère, J. S. R.; Lepine, B. A.; Dubois, J. M. S.

    2002-05-01

    Improving the detectability of fatigue cracks under installed fasteners is one of the many goals of the aging aircraft nondestructive evaluation (NDE) community. The pulsed eddy current offers new capabilities to address this requirement. The aim of the paper is to evaluate the potential of this technique for detecting and quantifying notches under installed fasteners.

  5. Nondestructive examination of recovery stage during annealing of a cold-rolled low-carbon steel using eddy current testing technique

    NASA Astrophysics Data System (ADS)

    Seyfpour, M.; Ghanei, S.; Mazinani, M.; Kashefi, M.; Davis, C.

    2018-04-01

    The recovery process in steel is usually investigated by conventional destructive tests that are expensive, time-consuming and also cumbersome. In this study, an alternative non-destructive test technique (based on eddy current testing) is used to characterise the recovery process during annealing of cold-rolled low-carbon steels. For assessing the reliability of eddy current results corresponding to different levels of recovery, X-ray line broadening analysis is also employed. It is shown that there is a strong relationship between eddy current outputs and the extent to which recovery occurs at different annealing temperatures. Accordingly, the non-destructive eddy current test technique represents the potential to be used as a reliable process for detection of the occurrence of recovery in the steel microstructure.

  6. Using eddy currents for noninvasive in vivo pH monitoring for bone tissue engineering.

    PubMed

    Beck-Broichsitter, Benedicta E; Daschner, Frank; Christofzik, David W; Knöchel, Reinhard; Wiltfang, Jörg; Becker, Stephan T

    2015-03-01

    The metabolic processes that regulate bone healing and bone induction in tissue engineering models are not fully understood. Eddy current excitation is widely used in technical approaches and in the food industry. The aim of this study was to establish eddy current excitation for monitoring metabolic processes during heterotopic osteoinduction in vivo. Hydroxyapatite scaffolds were implanted into the musculus latissimus dorsi of six rats. Bone morphogenetic protein 2 (BMP-2) was applied 1 and 2 weeks after implantation. Weekly eddy current excitation measurements were performed. Additionally, invasive pH measurements were obtained from the scaffolds using fiber optic detection devices. Correlations between the eddy current measurements and the metabolic values were calculated. The eddy current measurements and pH values decreased significantly in the first 2 weeks of the study, followed by a steady increase and stabilization at higher levels towards the end of the study. The measurement curves and statistical evaluations indicated a significant correlation between the resonance frequency values of the eddy current excitation measurements and the observed pH levels (p = 0.0041). This innovative technique was capable of noninvasively monitoring metabolic processes in living tissues according to pH values, showing a direct correlation between eddy current excitation and pH in an in vivo tissue engineering model.

  7. Eddy correlation measurements of size-dependent cloud droplet turbulent fluxes to complex terrain

    NASA Astrophysics Data System (ADS)

    Vong, Richard J.; Kowalski, Andrew S.

    1995-07-01

    An eddy correlation technique was used to measure the turbulent flux of cloud droplets to complex, forested terrain near the coast of Washington State during the spring of 1993. Excellent agreement was achieved for cloud liquid water content measured by two instruments. Substantial downward liquid water fluxes of ~ 1mm per 24 h were measured at night during "steady and continuous" cloud events, about twice the magnitude of those measured by Beswick etal. in Scotland. Cloud water chemical fluxes were estimated to represent up to 50% of the chemical deposition associated with precipitation at the site. An observed size-dependence in the turbulent liquid water fluxes suggested that both droplet impaction, which leads to downward fluxes, and phase change processes, which can lead to upward fluxes, consistently are important contributors to the eddy correlation results. The diameter below which phase change processes were important to observed fluxes was shown to depend upon σLL, the relative standard deviation of the liquid water content (LWC) within a 30-min averaging period. The crossover from upward to downward LW flux occurs at 8µm for steady and continuous cloud events but at ~ 13µm for events with a larger degree of LWC variability. This comparison of the two types of cloud events suggested that evaporation was the most likely cause of upward droplet fluxes for the smaller droplets (dia<13µm) during cloud with variable LWC (σLL>0.3).

  8. Application of an eddy correlation system for the estimation of oxygen benthic fluxes in coastal permeable sediments impacted by submarine groundwater discharge

    NASA Astrophysics Data System (ADS)

    Donis, D.; Janssen, F.; Böttcher, M.; McGinnis, D.; Holtappels, M.; Wenzhöfer, F.

    2012-04-01

    Measurements of solute exchange across the sediment-water interface are crucial for marine environment monitoring. This interface has fundamental filter functions for the mass exchange between the seafloor and the water column. Being a non-invasive technique, the eddy correlation method, is probably the most accurate measurement for benthic fluxes. It does not interfere with local hydrodynamics and integrates over large areas, showing considerable advantages compared to traditional methods, i.e., microprofiles and benthic chambers. One of the most important exchange processes across the sediment-water interface is flux of oxygen, which is a predominant control factor for the biogeochemical activity in the sediment, carbon processing and the composition of benthic communities. The eddy correlation method performs simultaneous recordings of vertical velocities and oxygen concentrations at a specific distance to the seafloor and is becoming a standard method for resolving dissolved oxygen fluxes in aquatic systems. However, data treatment and interpretation, especially in shallow environments, is still challenging. One major concern in eddy correlation studies of coastal environments is how to consider surface wave motions that can dominate the turbulence range and that may bias flux calculations. A critical part of the data treatment thus is the removal of wave biases from the vertical velocity component, by separating the wave frequency oscillations (due to a tilted or miss-aligned sensor) from those containing meaningful flux contributions. Here we present in situ benthic oxygen exchange rates as determined by an eddy correlation system (ECS) and simultaneously deployed stirred benthic chambers. The study was carried out in a coastal ecosystem of the southern Baltic Sea that was impacted by low salinity groundwater discharge (Hel peninsula, Poland). Oxygen fluxes determined with ECS compared well with results from benthic chambers. Flux data and seepage rates are

  9. Observation of methane fluxes using eddy covariance technique and relaxed eddy accumulation techniques simultaneously over rice paddies in Taiwan

    NASA Astrophysics Data System (ADS)

    Tang, M.; Tsai, J.; Tsuang, B.; Feng, P.; Kuo, P.

    2012-12-01

    In the past decades, more and more attention was given to the increase of atmospheric methane concentration from the scientific community. Methane is one of greenhouse gases with a global warming potential 21 times greater than carbon dioxide on a 100-year horizon. Rice paddy fields were considered as a major source for methane and so far there are few studies where the eddy covariance (EC) technique has been used to measure methane fluxes from rice paddy fields, especially in Asia. Therefore, in this study we used EC technique and relaxed eddy accumulation (REA) method simultaneously to observe the methane fluxes over rice paddy, fertilized with pig manure, in Taiwan from 22th February to 5th June in 2012. A suit of Micrometeorologial variables and water table depth were measured in conjunction with the fluxes. The results showed that the rice paddy field was source of methane during most of the study period and the observed methane fluxes ranged between - 0.5 and 13 μg m-2 s-1. and the maximum values usually occurred in the afternoon. A significant methane emission was observed in the first one and a half month after transplanting. Comparison of daily methane fluxes measured by EC and REA showed generally good agreement between both methods with a coefficient of determination of 0.81, although the magnitude of methane fluxes measured by REA were slightly lower than those by EC. During the continuous flooded period, the methane fluxes can be depicted well by a function of soil temperature with an exponential form. Sudden pulses of methane fluxes were observed when drained for the removal of obstruction which hindered the methane diffuse from the soil to the atmosphere. During fallow period between growth periods, the paddy fields was a sink of methane where the methane uptake was about 0.5μg m-2 s-1 around noon.

  10. Toward relaxed eddy accumulation measurements of sediment-water exchange in aquatic ecosystems

    NASA Astrophysics Data System (ADS)

    Lemaire, Bruno J.; Noss, Christian; Lorke, Andreas

    2017-09-01

    Solute transport across the sediment-water interface has major implications for water quality and biogeochemical cycling in aquatic ecosystems. Existing measurement techniques, however, are not capable of resolving sediment-water fluxes of most constituents under in situ flow conditions. We investigated whether relaxed eddy accumulation (REA), a micrometeorological technique with conditional sampling of turbulent updrafts and downdrafts, can be adapted to the aquatic environment. We simulated REA fluxes by reanalyzing eddy covariance measurements from a riverine lake. We found that the empirical coefficient that relates mass fluxes to the concentration difference between both REA samples is invariant with scalar and flow and responds as predicted by a joint Gaussian distribution of linearly correlated variables. Simulated REA fluxes differed on average by around 30% from eddy covariance fluxes (mean absolute error). Assessment of the lower quantification limit suggests that REA can potentially be applied for measuring benthic fluxes of a new range of constituents that cannot be assessed by standard eddy covariance methods.

  11. Tools and Methods for Visualization of Mesoscale Ocean Eddies

    NASA Astrophysics Data System (ADS)

    Bemis, K. G.; Liu, L.; Silver, D.; Kang, D.; Curchitser, E.

    2017-12-01

    Mesoscale ocean eddies form in the Gulf Stream and transport heat and nutrients across the ocean basin. The internal structure of these three-dimensional eddies and the kinematics with which they move are critical to a full understanding of their transport capacity. A series of visualization tools have been developed to extract, characterize, and track ocean eddies from 3D modeling results, to visually show the ocean eddy story by applying various illustrative visualization techniques, and to interactively view results stored on a server from a conventional browser. In this work, we apply a feature-based method to track instances of ocean eddies through the time steps of a high-resolution multidecadal regional ocean model and generate a series of eddy paths which reflect the life cycle of individual eddy instances. The basic method uses the Okubu-Weiss parameter to define eddy cores but could be adapted to alternative specifications of an eddy. Stored results include pixel-lists for each eddy instance, tracking metadata for eddy paths, and physical and geometric properties. In the simplest view, isosurfaces are used to display eddies along an eddy path. Individual eddies can then be selected and viewed independently or an eddy path can be viewed in the context of all eddy paths (longer than a specified duration) and the ocean basin. To tell the story of mesoscale ocean eddies, we combined illustrative visualization techniques, including visual effectiveness enhancement, focus+context, and smart visibility, with the extracted volume features to explore eddy characteristics at multiple scales from ocean basin to individual eddy. An evaluation by domain experts indicates that combining our feature-based techniques with illustrative visualization techniques provides an insight into the role eddies play in ocean circulation. A web-based GUI is under development to facilitate easy viewing of stored results. The GUI provides the user control to choose amongst available

  12. Nondestructive examination of decarburised layer of steels using eddy current and magnetic Barkhausen noise testing techniques

    NASA Astrophysics Data System (ADS)

    Falahat, S.; Ghanei, S.; Kashefi, M.

    2018-04-01

    Eddy current and Barkhausen noise nondestructive testing techniques were considered to evaluate the magnetic properties of the decarburised steels as a function of microstructure. To make changes in decarburising depth, carbon steel samples were austenitised at 890 °C for 120-270 min. Considering different decarburised depths, height, position and width of the noise profiles were extracted in order to analyse the magnetic Barkhausen noise measurements. Next, the eddy current test was performed to detect the changes in the microstructure through decarburising of the steel taking into account the impedance variations. According to the results, both techniques allow us to detect changes in the magnetic properties of the decarburised steels and link them with their microstructural changes, nondestructively.

  13. Detection and Sizing of Fatigue Cracks in Steel Welds with Advanced Eddy Current Techniques

    NASA Astrophysics Data System (ADS)

    Todorov, E. I.; Mohr, W. C.; Lozev, M. G.

    2008-02-01

    Butt-welded specimens were fatigued to produce cracks in the weld heat-affected zone. Advanced eddy current (AEC) techniques were used to detect and size the cracks through a coating. AEC results were compared with magnetic particle and phased-array ultrasonic techniques. Validation through destructive crack measurements was also conducted. Factors such as geometry, surface treatment, and crack tightness interfered with depth sizing. AEC inspection techniques have the potential of providing more accurate and complete sizing flaw data for manufacturing and in-service inspections.

  14. Large eddy simulation of incompressible turbulent channel flow

    NASA Technical Reports Server (NTRS)

    Moin, P.; Reynolds, W. C.; Ferziger, J. H.

    1978-01-01

    The three-dimensional, time-dependent primitive equations of motion were numerically integrated for the case of turbulent channel flow. A partially implicit numerical method was developed. An important feature of this scheme is that the equation of continuity is solved directly. The residual field motions were simulated through an eddy viscosity model, while the large-scale field was obtained directly from the solution of the governing equations. An important portion of the initial velocity field was obtained from the solution of the linearized Navier-Stokes equations. The pseudospectral method was used for numerical differentiation in the horizontal directions, and second-order finite-difference schemes were used in the direction normal to the walls. The large eddy simulation technique is capable of reproducing some of the important features of wall-bounded turbulent flows. The resolvable portions of the root-mean square wall pressure fluctuations, pressure velocity-gradient correlations, and velocity pressure-gradient correlations are documented.

  15. Development of Eddy Current Techniques for Detection of Deep Fatigue Cracks in Multi-Layer Airframe Components

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell A.

    2008-01-01

    Thick, multi-layer aluminum structure has been widely used in aircraft design in critical wing splice areas. The multi-layer structure generally consists of three or four aluminum layers with different geometry and varying thickness, which are held together with fasteners. The detection of cracks under fasteners with ultrasonic techniques in subsurface layers away from the skin is impeded primarily by interlayer bonds and faying sealant condition. Further, assessment of such sealant condition is extremely challenging in terms of complexity of structure, limited access, and inspection cost. Although Eddy current techniques can be applied on in-service aircraft from the exterior of the skin without knowing sealant condition, the current eddy current techniques are not able to detect defects with wanted sensitivity. In this work a series of low frequency eddy current probes have been designed, fabricated and tested for this application. A probe design incorporating a shielded magnetic field sensor concentrically located in the interior of a drive coil has been employed to enable a localized deep diffusion of the electromagnetic field into the part under test. Due to the required low frequency inspections, probes have been testing using a variety of magnetic field sensors (pickup coil, giant magneto-resistive, anisotropic magneto-resistive, and spin-dependent tunneling). The probe designs as well as capabilities based upon a target inspection for sub-layer cracking in an airframe wing spar joint is presented.

  16. Characteristic eddy decomposition of turbulence in a channel

    NASA Technical Reports Server (NTRS)

    Moin, Parviz; Moser, Robert D.

    1991-01-01

    The proper orthogonal decomposition technique (Lumley's decomposition) is applied to the turbulent flow in a channel to extract coherent structures by decomposing the velocity field into characteristic eddies with random coefficients. In the homogeneous spatial directions, a generaliztion of the shot-noise expansion is used to determine the characteristic eddies. In this expansion, the Fourier coefficients of the characteristic eddy cannot be obtained from the second-order statistics. Three different techniques are used to determine the phases of these coefficients. They are based on: (1) the bispectrum, (2) a spatial compactness requirement, and (3) a functional continuity argument. Results from these three techniques are found to be similar in most respects. The implications of these techniques and the shot-noise expansion are discussed. The dominant eddy is found to contribute as much as 76 percent to the turbulent kinetic energy. In both 2D and 3D, the characteristic eddies consist of an ejection region straddled by streamwise vortices that leave the wall in the very short streamwise distance of about 100 wall units.

  17. Analysis of Grassland Ecosystem Physiology at Multiple Scales Using Eddy Covariance, Stable Isotope and Remote Sensing Techniques

    NASA Astrophysics Data System (ADS)

    Flanagan, L. B.; Geske, N.; Emrick, C.; Johnson, B. G.

    2006-12-01

    Grassland ecosystems typically exhibit very large annual fluctuations in above-ground biomass production and net ecosystem productivity (NEP). Eddy covariance flux measurements, plant stable isotope analyses, and canopy spectral reflectance techniques have been applied to study environmental constraints on grassland ecosystem productivity and the acclimation responses of the ecosystem at a site near Lethbridge, Alberta, Canada. We have observed substantial interannual variation in grassland productivity during 1999-2005. In addition, there was a strong correlation between peak above-ground biomass production and NEP calculated from eddy covariance measurements. Interannual variation in NEP was strongly controlled by the total amount of precipitation received during the growing season (April-August). We also observed significant positive correlations between a multivariate ENSO index and total growing season precipitation, and between the ENSO index and annual NEP values. This suggested that a significant fraction of the annual variability in grassland productivity was associated with ENSO during 1999-2005. Grassland productivity varies asymmetrically in response to changes in precipitation with increases in productivity during wet years being much more pronounced than reductions during dry years. Strong increases in plant water-use efficiency, based on carbon and oxygen stable isotope analyses, contribute to the resilience of productivity during times of drought. Within a growing season increased stomatal limitation of photosynthesis, associated with improved water-use efficiency, resulted in apparent shifts in leaf xanthophyll cycle pigments and changes to the Photochemical Reflectance Index (PRI) calculated from hyper-spectral reflectance measurements conducted at the canopy-scale. These shifts in PRI were apparent before seasonal drought caused significant reductions in leaf area index (LAI) and changes to canopy-scale "greenness" based on NDVI values. With

  18. Development of Eddy Current Techniques for the Detection of Cracking in Space Shuttle Primary Reaction Control Thrusters

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz A.; Simpson, John W.; Koshti, Ajay

    2007-01-01

    A recent identification of cracking in the Space Shuttle Primary Reaction Control System (PRCS) thrusters triggered an extensive nondestructive evaluation effort to develop techniques capable of identifying such damage on installed shuttle hardware. As a part of this effort, specially designed eddy current probes inserted into the acoustic cavity were explored for the detection of such flaws and for evaluation of the remaining material between the crack tip and acoustic cavity. The technique utilizes two orthogonal eddy current probes which are scanned under stepper motor control in the acoustic cavity to identify cracks hidden with as much as 0.060 remaining wall thickness to the cavity. As crack growth rates in this area have been determined to be very slow, such an inspection provides a large safety margin for continued operation of the critical shuttle hardware. Testing has been performed on thruster components with both actual and fabricated defects. This paper will review the design and performance of the developed eddy current inspection system. Detection of flaws as a function of remaining wall thickness will be presented along with the proposed system configuration for depot level or on-vehicle inspection capabilities.

  19. Aquatic Eddy Correlation: Quantifying the Artificial Flux Caused by Stirring-Sensitive O2 Sensors

    PubMed Central

    Holtappels, Moritz; Noss, Christian; Hancke, Kasper; Cathalot, Cecile; McGinnis, Daniel F.; Lorke, Andreas; Glud, Ronnie N.

    2015-01-01

    In the last decade, the aquatic eddy correlation (EC) technique has proven to be a powerful approach for non-invasive measurements of oxygen fluxes across the sediment water interface. Fundamental to the EC approach is the correlation of turbulent velocity and oxygen concentration fluctuations measured with high frequencies in the same sampling volume. Oxygen concentrations are commonly measured with fast responding electrochemical microsensors. However, due to their own oxygen consumption, electrochemical microsensors are sensitive to changes of the diffusive boundary layer surrounding the probe and thus to changes in the ambient flow velocity. The so-called stirring sensitivity of microsensors constitutes an inherent correlation of flow velocity and oxygen sensing and thus an artificial flux which can confound the benthic flux determination. To assess the artificial flux we measured the correlation between the turbulent flow velocity and the signal of oxygen microsensors in a sealed annular flume without any oxygen sinks and sources. Experiments revealed significant correlations, even for sensors designed to have low stirring sensitivities of ~0.7%. The artificial fluxes depended on ambient flow conditions and, counter intuitively, increased at higher velocities because of the nonlinear contribution of turbulent velocity fluctuations. The measured artificial fluxes ranged from 2 - 70 mmol m-2 d-1 for weak and very strong turbulent flow, respectively. Further, the stirring sensitivity depended on the sensor orientation towards the flow. For a sensor orientation typically used in field studies, the artificial flux could be predicted using a simplified mathematical model. Optical microsensors (optodes) that should not exhibit a stirring sensitivity were tested in parallel and did not show any significant correlation between O2 signals and turbulent flow. In conclusion, EC data obtained with electrochemical sensors can be affected by artificial flux and we recommend

  20. Detecting defects in marine structures by using eddy current infrared thermography.

    PubMed

    Swiderski, W

    2016-12-01

    Eddy current infrared (IR) thermography is a new nondestructive testing (NDT) technique used for the detection of cracks in electroconductive materials. By combining the well-established inspection methods of eddy current NDT and IR thermography, this technique uses induced eddy currents to heat test samples. In this way, IR thermography allows the visualization of eddy current distribution that is distorted in defect sites. This paper discusses the results of numerical modeling of eddy current IR thermography procedures in application to marine structures.

  1. Study of eddy current probes

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.; Wang, Morgan

    1992-01-01

    The recognition of materials properties still presents a number of problems for nondestructive testing in aerospace systems. This project attempts to utilize current capabilities in eddy current instrumentation, artificial intelligence, and robotics in order to provide insight into defining geometrical aspects of flaws in composite materials which are capable of being evaluated using eddy current inspection techniques.

  2. Unified Ultrasonic/Eddy-Current Data Acquisition

    NASA Technical Reports Server (NTRS)

    Chern, E. James; Butler, David W.

    1993-01-01

    Imaging station for detecting cracks and flaws in solid materials developed combining both ultrasonic C-scan and eddy-current imaging. Incorporation of both techniques into one system eliminates duplication of computers and of mechanical scanners; unifies acquisition, processing, and storage of data; reduces setup time for repetitious ultrasonic and eddy-current scans; and increases efficiency of system. Same mechanical scanner used to maneuver either ultrasonic or eddy-current probe over specimen and acquire point-by-point data. For ultrasonic scanning, probe linked to ultrasonic pulser/receiver circuit card, while, for eddy-current imaging, probe linked to impedance-analyzer circuit card. Both ultrasonic and eddy-current imaging subsystems share same desktop-computer controller, containing dedicated plug-in circuit boards for each.

  3. Automated eddy current analysis of materials

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1991-01-01

    The use of eddy current techniques for characterizing flaws in graphite-based filament-wound cylindrical structures is described. A major emphasis was also placed upon incorporating artificial intelligence techniques into the signal analysis portion of the inspection process. Developing an eddy current scanning system using a commercial robot for inspecting graphite structures (and others) was a goal in the overall concept and is essential for the final implementation for the expert systems interpretation. Manual scans, as performed in the preliminary work here, do not provide sufficiently reproducible eddy current signatures to be easily built into a real time expert system. The expert systems approach to eddy current signal analysis requires that a suitable knowledge base exist in which correct decisions as to the nature of a flaw can be performed. A robotic workcell using eddy current transducers for the inspection of carbon filament materials with improved sensitivity was developed. Improved coupling efficiencies achieved with the E-probes and horseshoe probes are exceptional for graphite fibers. The eddy current supervisory system and expert system was partially developed on a MacIvory system. Continued utilization of finite element models for predetermining eddy current signals was shown to be useful in this work, both for understanding how electromagnetic fields interact with graphite fibers, and also for use in determining how to develop the knowledge base. Sufficient data was taken to indicate that the E-probe and the horseshoe probe can be useful eddy current transducers for inspecting graphite fiber components. The lacking component at this time is a large enough probe to have sensitivity in both the far and near field of a thick graphite epoxy component.

  4. Quantitative void fraction detection with an eddy current flowmeter for generation IV Sodium cooled Fast Reactor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, M.; French Atomic Energy and Alternative Energies Commission; Tordjeman, Ph.

    2015-07-01

    This study was carried out to understand the response of an eddy current type flowmeter in two phase liquid-metal flow. We use the technique of ellipse fit and correlate the fluctuations in the angle of inclination of this ellipse with the void fraction. The effects of physical parameters such as coil excitation frequency and flow velocity have been studied. The results show the possibility of using an eddy current flowmeter as a gas detector for large void fractions. (authors)

  5. Quantitative void fraction measurement with an eddy current flowmeter for generation IV Sodium cooled Fast Reactor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kumar, M.; CEA, DEN, Nuclear Technology Department, F-13108 Saint-Paul-lez-Durance; Tordjeman, Ph.

    2015-07-01

    This study was carried out to understand the response of an eddy current type flowmeter in two phase liquid-metal flow. We use the technique of ellipse fit and correlate the fluctuations in the angle of inclination of this ellipse with the void fraction. The effects of physical parameters such as coil excitation frequency and flow velocity have been studied. The results show the possibility of using an eddy current flowmeter as a gas detector for large void fractions. (authors)

  6. Development of Eddy Current Technique for the Detection of Stress Corrosion Cracking in Space Shuttle Primary Reaction Control Thrusters

    NASA Technical Reports Server (NTRS)

    Wincheski, Buzz; Simpson, John; Koshti, Ajay

    2006-01-01

    A recent identification of stress corrosion cracking in the Space Shuttle Primary Reaction Control System (PRCS) thrusters triggered an extensive nondestructive evaluation effort to develop techniques capable of identifying such damage on installed shuttle hardware. As a part of this effort, specially designed eddy current probes inserted into the acoustic cavity were explored for the detection of such flaws and for evaluation of the remaining material between the crack tip and acoustic cavity. The technique utilizes two orthogonal eddy current probes which are scanned under stepper motor control in the acoustic cavity to identify cracks hidden with as much as 0.060 remaining wall thickness to the cavity. As crack growth rates in this area have been determined to be very slow, such an inspection provides a large safety margin for continued operation of the critical shuttle hardware. Testing has been performed on thruster components with both actual and fabricated defects. This paper will review the design and performance of the developed eddy current inspection system. Detection of flaws as a function of remaining wall thickness will be presented along with the proposed system configuration for depot level or on-vehicle inspection capabilities.

  7. Nuclear Technology. Course 32: Nondestructive Examination (NDE) Techniques II. Module 32-5, Fundamentals of Eddy Current Testing.

    ERIC Educational Resources Information Center

    Espy, John

    This fifth in a series of six modules for a course titled Nondestructive Examination (NDE) Techniques II describes the fundamental concepts applicable to eddy current testing in general. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3) objectives, (4) notes to…

  8. Nonperiodic eddy pulsations

    USGS Publications Warehouse

    Rubin, David M.; McDonald, Richard R.

    1995-01-01

    Recirculating flow in lateral separation eddies is typically weaker than main stem flow and provides an effective environment for trapping sediment. Observations of recirculating flow and sedimentary structures demonstrate that eddies pulsate in size and in flow velocity even when main stem flow is steady. Time series measurements of flow velocity and location of the reattachment point indicate that these pulsations are nonperiodic. Nonperiodic flow in the lee of a channel margin constriction is grossly different from the periodic flow in the lee of a cylinder that is isolated in a flow. Our experiments demonstrate that placing a flow-parallel plate adjacent to a cylinder is sufficient to cause the leeside flow to change from a periodic sequence of vortices to a nonperiodically pulsating lateral separation eddy, even if flow conditions are otherwise unchanged. Two processes cause the leeside flow to become nonperiodic when the plate is added. First, vortices that are shed from the cylinder deform and become irregular as they impact the plate or interfere with remnants of other vortices near the reattachment point. Second, these deformed vortices and other flow structures are recirculated in the lateral separation eddy, thereby influencing the future state (pressure and momentum distribution) of the recirculating flow. The vortex deformation process was confirmed experimentally by documenting spatial differences in leeside flow; vortex shedding that is evident near the separation point is undetectable near the reattachment point. Nonlinear forecasting techniques were used in an attempt to distinguish among several possible kinds of nonperiodic flows. The computational techniques were unable to demonstrate that any of the nonperiodic flows result from low-dimensional nonlinear processes.

  9. From Phenomena to Objects: Segmentation of Fuzzy Objects and its Application to Oceanic Eddies

    NASA Astrophysics Data System (ADS)

    Wu, Qingling

    A challenging image analysis problem that has received limited attention to date is the isolation of fuzzy objects---i.e. those with inherently indeterminate boundaries---from continuous field data. This dissertation seeks to bridge the gap between, on the one hand, the recognized need for Object-Based Image Analysis of fuzzy remotely sensed features, and on the other, the optimization of existing image segmentation techniques for the extraction of more discretely bounded features. Using mesoscale oceanic eddies as a case study of a fuzzy object class evident in Sea Surface Height Anomaly (SSHA) imagery, the dissertation demonstrates firstly, that the widely used region-growing and watershed segmentation techniques can be optimized and made comparable in the absence of ground truth data using the principle of parsimony. However, they both have significant shortcomings, with the region growing procedure creating contour polygons that do not follow the shape of eddies while the watershed technique frequently subdivides eddies or groups together separate eddy objects. Secondly, it was determined that these problems can be remedied by using a novel Non-Euclidian Voronoi (NEV) tessellation technique. NEV is effective in isolating the extrema associated with eddies in SSHA data while using a non-Euclidian cost-distance based procedure (based on cumulative gradients in ocean height) to define the boundaries between fuzzy objects. Using this procedure as the first stage in isolating candidate eddy objects, a novel "region-shrinking" multicriteria eddy identification algorithm was developed that includes consideration of shape and vorticity. Eddies identified by this region-shrinking technique compare favorably with those identified by existing techniques, while simplifying and improving existing automated eddy detection algorithms. However, it also tends to find a larger number of eddies as a result of its ability to separate what other techniques identify as connected

  10. CCD correlation techniques

    NASA Technical Reports Server (NTRS)

    Hewes, C. R.; Bosshart, P. W.; Eversole, W. L.; Dewit, M.; Buss, D. D.

    1976-01-01

    Two CCD techniques were discussed for performing an N-point sampled data correlation between an input signal and an electronically programmable reference function. The design and experimental performance of an implementation of the direct time correlator utilizing two analog CCDs and MOS multipliers on a single IC were evaluated. The performance of a CCD implementation of the chirp z transform was described, and the design of a new CCD integrated circuit for performing correlation by multiplication in the frequency domain was presented. This chip provides a discrete Fourier transform (DFT) or inverse DFT, multipliers, and complete support circuitry for the CCD CZT. The two correlation techniques are compared.

  11. Inexpensive Eddy-Current Standard

    NASA Technical Reports Server (NTRS)

    Berry, Robert F., Jr.

    1985-01-01

    Radial crack replicas serve as evaluation standards. Technique entails intimately joining two pieces of appropriate aluminum alloy stock and centering drilled hole through and along interface. Bore surface of hole presents two vertical stock interface lines 180 degrees apart. These lines serve as radial crack defect replicas during eddy-current technique setup and verification.

  12. Nonlinear Eddy-Eddy Interactions in Dry Atmospheres Macroturbulence

    NASA Astrophysics Data System (ADS)

    Ait Chaalal, F.; Schneider, T.

    2012-12-01

    The statistical moment equations derived from the atmospheric equation of motions are not closed. However neglecting the large-scale eddy-eddy nonlinear interactions in an idealized dry general circulation model (GCM), which is equivalent to truncating the moment equations at the second order, can reproduce some of the features of the general circulation ([1]), highlighting the significance of eddy-mean flow interactions and the weakness of eddy-eddy interactions in atmospheric macroturbulence ([2]). The goal of the present study is to provide new insight into the rôle of these eddy-eddy interactions and discuss the relevance of a simple stochastic parametrization to represent them. We investigate in detail the general circulation in an idealized dry GCM, comparing full simulations with simulations where the eddy-eddy interactions are removed. The radiative processes are parametrized through Newtonian relaxation toward a radiative-equilibrium state with a prescribed equator to pole temperature contrast. A convection scheme relaxing toward a prescribed convective vertical lapse rate mimics some aspects of moist convection. The study is performed over a wide range of parameters covering the planetary rotation rate, the equator to pole temperature contrast and the vertical lapse rate. Particular attention is given to the wave-mean flow interactions and to the spectral budget. It is found that the no eddy-eddy simulations perform well when the baroclinic activity is weaker, for example for lower equator to pole temperature contrasts or higher rotation rates: the mean meridional circulation is well reproduced, with realistic eddy-driven jets and energy-containing eddy length scales of the order of the Rossby deformation radius. For a stronger baroclinic activity the no eddy-eddy model does not achieve a realistic isotropization of the eddies, the meridional circulation is compressed in the meridional direction and secondary eddy-driven jets emerge. In addition, the

  13. Large Eddy Simulation of a Turbulent Jet

    NASA Technical Reports Server (NTRS)

    Webb, A. T.; Mansour, Nagi N.

    2001-01-01

    Here we present the results of a Large Eddy Simulation of a non-buoyant jet issuing from a circular orifice in a wall, and developing in neutral surroundings. The effects of the subgrid scales on the large eddies have been modeled with the dynamic large eddy simulation model applied to the fully 3D domain in spherical coordinates. The simulation captures the unsteady motions of the large-scales within the jet as well as the laminar motions in the entrainment region surrounding the jet. The computed time-averaged statistics (mean velocity, concentration, and turbulence parameters) compare well with laboratory data without invoking an empirical entrainment coefficient as employed by line integral models. The use of the large eddy simulation technique allows examination of unsteady and inhomogeneous features such as the evolution of eddies and the details of the entrainment process.

  14. Characteristic-eddy decomposition of turbulence in a channel

    NASA Technical Reports Server (NTRS)

    Moin, Parviz; Moser, Robert D.

    1989-01-01

    Lumley's proper orthogonal decomposition technique is applied to the turbulent flow in a channel. Coherent structures are extracted by decomposing the velocity field into characteristic eddies with random coefficients. A generalization of the shot-noise expansion is used to determine the characteristic eddies in homogeneous spatial directions. Three different techniques are used to determine the phases of the Fourier coefficients in the expansion: (1) one based on the bispectrum, (2) a spatial compactness requirement, and (3) a functional continuity argument. Similar results are found from each of these techniques.

  15. Automated eddy current analysis of materials

    NASA Technical Reports Server (NTRS)

    Workman, Gary L.

    1990-01-01

    This research effort focused on the use of eddy current techniques for characterizing flaws in graphite-based filament-wound cylindrical structures. A major emphasis was on incorporating artificial intelligence techniques into the signal analysis portion of the inspection process. Developing an eddy current scanning system using a commercial robot for inspecting graphite structures (and others) has been a goal in the overall concept and is essential for the final implementation for expert system interpretation. Manual scans, as performed in the preliminary work here, do not provide sufficiently reproducible eddy current signatures to be easily built into a real time expert system. The expert systems approach to eddy current signal analysis requires that a suitable knowledge base exist in which correct decisions as to the nature of the flaw can be performed. In eddy current or any other expert systems used to analyze signals in real time in a production environment, it is important to simplify computational procedures as much as possible. For that reason, we have chosen to use the measured resistance and reactance values for the preliminary aspects of this work. A simple computation, such as phase angle of the signal, is certainly within the real time processing capability of the computer system. In the work described here, there is a balance between physical measurements and finite element calculations of those measurements. The goal is to evolve into the most cost effective procedures for maintaining the correctness of the knowledge base.

  16. Nuclear Technology. Course 32: Nondestructive Examination (NDE) Techniques II. Module 32-6, Operation of Eddy Current Test Equipment.

    ERIC Educational Resources Information Center

    Espy, John; Selleck, Ben

    This sixth in a series of six modules for a course titled Nondestructive Examination (NDE) Techniques II details eddy current examination of steam generator tubing. The module follows a typical format that includes the following sections: (1) introduction, (2) module prerequisites, (3) objectives, (4) notes to instructor/student, (5) subject…

  17. Mitigation of eddy current heating during magnetic nanoparticle hyperthermia therapy.

    PubMed

    Stigliano, Robert V; Shubitidze, Fridon; Petryk, James D; Shoshiashvili, Levan; Petryk, Alicia A; Hoopes, P Jack

    2016-11-01

    Magnetic nanoparticle hyperthermia therapy is a promising technology for cancer treatment, involving delivering magnetic nanoparticles (MNPs) into tumours then activating them using an alternating magnetic field (AMF). The system produces not only a magnetic field, but also an electric field which penetrates normal tissue and induces eddy currents, resulting in unwanted heating of normal tissues. Magnitude of the eddy current depends, in part, on the AMF source and the size of the tissue exposed to the field. The majority of in vivo MNP hyperthermia therapy studies have been performed in small animals, which, due to the spatial distribution of the AMF relative to the size of the animals, do not reveal the potential toxicity of eddy current heating in larger tissues. This has posed a non-trivial challenge for researchers attempting to scale up to clinically relevant volumes of tissue. There is a relative dearth of studies focused on decreasing the maximum temperature resulting from eddy current heating to increase therapeutic ratio. This paper presents two simple, clinically applicable techniques for decreasing maximum temperature induced by eddy currents. Computational and experimental results are presented to understand the underlying physics of eddy currents induced in conducting, biological tissues and leverage these insights to mitigate eddy current heating during MNP hyperthermia therapy. Phantom studies show that the displacement and motion techniques reduce maximum temperature due to eddy currents by 74% and 19% in simulation, and by 77% and 33% experimentally. Further study is required to optimise these methods for particular scenarios; however, these results suggest larger volumes of tissue could be treated, and/or higher field strengths and frequencies could be used to attain increased MNP heating when these eddy current mitigation techniques are employed.

  18. Development of airborne eddy-correlation flux measurement capabilities for reactive oxides of nitrogen

    NASA Technical Reports Server (NTRS)

    Bradshaw, John (Principal Investigator); Zheng, Xiaonan; Sandholm, Scott T.

    1996-01-01

    This research is aimed at producing a fundamental new research tool for characterizing the source strength of the most important compound controlling the hemispheric and global scale distribution of tropospheric ozone. Specifically, this effort seeks to demonstrate the proof-of-concept of a new general purpose laser-induced fluorescence based spectrometer for making airborne eddy-correlation flux measurements of nitric oxide (NO) and other reactive nitrogen compounds. The new all solid-state laser technology being used in this advanced sensor will produce a forerunner of the type of sensor technology that should eventually result in highly compact operational systems. The proof-of-concept sensor being developed will have over two orders-of-magnitude greater sensitivity than present-day instruments. In addition, this sensor will offer the possibility of eventual extension to airborne eddy-correlation flux measurements of nitrogen dioxide (NO2) and possibly other compounds, such as ammonia (NH3), peroxyradicals (HO2), nitrateradicals (NO3) and several iodine compounds (e.g., I and IO). Demonstration of the new sensor's ability to measure NO fluxes will occur through a series of laboratory and field tests. This proof-of-concept demonstration will show that not only can airborne fluxes of important ultra-trace compounds be made at the few parts-per-trillion level, but that the high accuracy/precision measurements currently needed for predictive models can also. These measurement capabilities will greatly enhance our current ability to quantify the fluxes of reactive nitrogen into the troposphere and significantly impact upon the accuracy of predictive capabilities to model O3's distribution within the remote troposphere. This development effort also offers a timely approach for producing the reactive nitrogen flux measurement capabilities that will be needed by future research programs such as NASA's planned 1999 Amazon Biogeochemistry and Atmospheric Chemistry

  19. A technique for estimating dry deposition velocities based on similarity with latent heat flux

    NASA Astrophysics Data System (ADS)

    Pleim, Jonathan E.; Finkelstein, Peter L.; Clarke, John F.; Ellestad, Thomas G.

    Field measurements of chemical dry deposition are needed to assess impacts and trends of airborne contaminants on the exposure of crops and unmanaged ecosystems as well as for the development and evaluation of air quality models. However, accurate measurements of dry deposition velocities require expensive eddy correlation measurements and can only be practically made for a few chemical species such as O 3 and CO 2. On the other hand, operational dry deposition measurements such as those used in large area networks involve relatively inexpensive standard meteorological and chemical measurements but rely on less accurate deposition velocity models. This paper describes an intermediate technique which can give accurate estimates of dry deposition velocity for chemical species which are dominated by stomatal uptake such as O 3 and SO 2. This method can give results that are nearly the quality of eddy correlation measurements of trace gas fluxes at much lower cost. The concept is that bulk stomatal conductance can be accurately estimated from measurements of latent heat flux combined with standard meteorological measurements of humidity, temperature, and wind speed. The technique is tested using data from a field experiment where high quality eddy correlation measurements were made over soybeans. Over a four month period, which covered the entire growth cycle, this technique showed very good agreement with eddy correlation measurements for O 3 deposition velocity.

  20. Revolving Eddy-Current Probe Detects Cracks Near Rivets

    NASA Technical Reports Server (NTRS)

    Namkung, Min; Wincheski, Buzz; Fulton, James P.; Nath, Shridhar; Simpson, John

    1995-01-01

    Scanning eddy-current probe in circular pattern increases sensitivity with which probe indicates fatigue cracks and other defects in metal surfaces in vicinity of rivets. Technique devised to facilitate inspection of riveted joints in aircraft. Eddy-current probe in question described in "Electro-magnetic Flaw Detector Is Easier To Use" (LAR-15046).

  1. Methane fluxes above the Hainich forest by True Eddy Accumulation and Eddy Covariance

    NASA Astrophysics Data System (ADS)

    Siebicke, Lukas; Gentsch, Lydia; Knohl, Alexander

    2016-04-01

    Understanding the role of forests for the global methane cycle requires quantifying vegetation-atmosphere exchange of methane, however observations of turbulent methane fluxes remain scarce. Here we measured turbulent fluxes of methane (CH4) above a beech-dominated old-growth forest in the Hainich National Park, Germany, and validated three different measurement approaches: True Eddy Accumulation (TEA, closed-path laser spectroscopy), and eddy covariance (EC, open-path and closed-path laser spectroscopy, respectively). The Hainich flux tower is a long-term Fluxnet and ICOS site with turbulent fluxes and ecosystem observations spanning more than 15 years. The current study is likely the first application of True Eddy Accumulation (TEA) for the measurement of turbulent exchange of methane and one of the very few studies comparing open-path and closed-path eddy covariance (EC) setups side-by-side. We observed uptake of methane by the forest during the day (a methane sink with a maximum rate of 0.03 μmol m-2 s-1 at noon) and no or small fluxes of methane from the forest to the atmosphere at night (a methane source of typically less than 0.01 μmol m-2 s-1) based on continuous True Eddy Accumulation measurements in September 2015. First results comparing TEA to EC CO2 fluxes suggest that True Eddy Accumulation is a valid option for turbulent flux quantifications using slow response gas analysers (here CRDS laser spectroscopy, other potential techniques include mass spectroscopy). The TEA system was one order of magnitude more energy efficient compared to closed-path eddy covariance. The open-path eddy covariance setup required the least amount of user interaction but is often constrained by low signal-to-noise ratios obtained when measuring methane fluxes over forests. Closed-path eddy covariance showed good signal-to-noise ratios in the lab, however in the field it required significant amounts of user intervention in addition to a high power consumption. We conclude

  2. Efficacy of distortion correction on diffusion imaging: comparison of FSL eddy and eddy_correct using 30 and 60 directions diffusion encoding.

    PubMed

    Yamada, Haruyasu; Abe, Osamu; Shizukuishi, Takashi; Kikuta, Junko; Shinozaki, Takahiro; Dezawa, Ko; Nagano, Akira; Matsuda, Masayuki; Haradome, Hiroki; Imamura, Yoshiki

    2014-01-01

    Diffusion imaging is a unique noninvasive tool to detect brain white matter trajectory and integrity in vivo. However, this technique suffers from spatial distortion and signal pileup or dropout originating from local susceptibility gradients and eddy currents. Although there are several methods to mitigate these problems, most techniques can be applicable either to susceptibility or eddy-current induced distortion alone with a few exceptions. The present study compared the correction efficiency of FSL tools, "eddy_correct" and the combination of "eddy" and "topup" in terms of diffusion-derived fractional anisotropy (FA). The brain diffusion images were acquired from 10 healthy subjects using 30 and 60 directions encoding schemes based on the electrostatic repulsive forces. For the 30 directions encoding, 2 sets of diffusion images were acquired with the same parameters, except for the phase-encode blips which had opposing polarities along the anteroposterior direction. For the 60 directions encoding, non-diffusion-weighted and diffusion-weighted images were obtained with forward phase-encoding blips and non-diffusion-weighted images with the same parameter, except for the phase-encode blips, which had opposing polarities. FA images without and with distortion correction were compared in a voxel-wise manner with tract-based spatial statistics. We showed that images corrected with eddy and topup possessed higher FA values than images uncorrected and corrected with eddy_correct with trilinear (FSL default setting) or spline interpolation in most white matter skeletons, using both encoding schemes. Furthermore, the 60 directions encoding scheme was superior as measured by increased FA values to the 30 directions encoding scheme, despite comparable acquisition time. This study supports the combination of eddy and topup as a superior correction tool in diffusion imaging rather than the eddy_correct tool, especially with trilinear interpolation, using 60 directions

  3. Eddy-correlation measurements of fluxes of CO 2 and H 2O above a spruce stand

    NASA Astrophysics Data System (ADS)

    Ibrom, A.; Schütz, C.; Tworek, T.; Morgenstern, K.; Oltchev, A.; Falk, M.; Constantin, J.; Gravenhorst, G.

    1996-12-01

    Atmospheric fluxes of CO 2 and H 2O above a mature spruce stand ( Picea abies (L.) Karst.) have been investigated using the eddy- correlation technique. A closed path sensor adapted to the special requirements of long-term studies has been developed and tested. Field measurements have been performed since April 1995. Estimates of fetch showed a very narrow source area dimension under instable stratification (≤ 200 m). Fetch requirements at night are not met in some directions. Energy balance closure was influenced systematically by the wind direction indicating a substantial attenuation of the vertical wind motion by the tower (up to 40 %). Even for optimal flow directions, energy balance closure was about 88%. Intercomparison of the used ultra sonic anemometer (USAT-3) with a GILL - anemometer showed systematically lower values of vertical wind speed fluctuations (13 %). Average CO 2-fluxes ranged between -13 at noon to 3 μ mol m-2, s-1 at night in summer. In November and December the stand released CO 2 on a daily basis. A preliminary estimate of the cumulative net carbon balance over the observed period of 9 months is 4-5 t, Cha-1.

  4. Non-destructive testing of composite materials used in military applications by eddy current thermography method

    NASA Astrophysics Data System (ADS)

    Swiderski, Waldemar

    2016-10-01

    Eddy current thermography is a new NDT-technique for the detection of cracks in electro conductive materials. It combines the well-established inspection techniques of eddy current testing and thermography. The technique uses induced eddy currents to heat the sample being tested and defect detection is based on the changes of induced eddy currents flows revealed by thermal visualization captured by an infrared camera. The advantage of this method is to use the high performance of eddy current testing that eliminates the known problem of the edge effect. Especially for components of complex geometry this is an important factor which may overcome the increased expense for inspection set-up. The paper presents the possibility of applying eddy current thermography method for detecting defects in ballistic covers made of carbon fiber reinforced composites used in the construction of military vehicles.

  5. Evaluation of eddy current and magnetic techniques for inspecting rebars in bridge barrier rails

    NASA Astrophysics Data System (ADS)

    Lo, C. C. H.; Nakagawa, N.

    2013-01-01

    This paper reports on a feasibility study of using eddy current (EC) and magnetic flux leakage (MFL) methods to detect corrosion damage in rebars that anchor concrete barrier rails to the road deck of bridge structures. EC and MFL measurements were carried out on standalone rebars with and without artificial defects of 25% and 50% material loss, using a commercial EC-based rebar locator and a MFL system that was developed using giant magnetoresistance sensors to detect leakage fluxes from the defects. Both techniques can readily detect the defects at a distance of 2.5″ (63.5 mm). The amplitudes of the EC and MFL signals vary monotonically with the amount of material loss, indicating the potential of using the techniques to quantify material loss of standalone rebars.

  6. Eddy current inspection of graphite fiber components

    NASA Technical Reports Server (NTRS)

    Workman, G. L.; Bryson, C. C.

    1990-01-01

    The recognition of defects in materials properties still presents a number of problems for nondestructive testing in aerospace systems. This project attempts to utilize current capabilities in eddy current instrumentation, artificial intelligence, and robotics in order to provide insight into defining geometrical aspects of flaws in composite materials which are capable of being evaluated using eddy current inspection techniques. The unique capabilities of E-probes and horseshoe probes for inspecting probes for inspecting graphite fiber materials were evaluated and appear to hold great promise once the technology development matures. The initial results are described of modeling eddy current interactions with certain flaws in graphite fiber samples.

  7. Eddy current correction in volume-localized MR spectroscopy

    NASA Technical Reports Server (NTRS)

    Lin, C.; Wendt, R. E. 3rd; Evans, H. J.; Rowe, R. M.; Hedrick, T. D.; LeBlanc, A. D.

    1994-01-01

    The quality of volume-localized magnetic resonance spectroscopy is affected by eddy currents caused by gradient switching. Eddy currents can be reduced with improved gradient systems; however, it has been suggested that the distortion due to eddy currents can be compensated for during postprocessing with a single-frequency reference signal. The authors propose modifying current techniques for acquiring the single-frequency reference signal by using relaxation weighting to reduce interference from components that cannot be eliminated by digital filtering alone. Additional sequences with T1 or T2 weighting for reference signal acquisition are shown to have the same eddy current characteristics as the original signal without relaxation weighting. The authors also studied a new eddy current correction method that does not require a single-frequency reference signal. This method uses two free induction decays (FIDs) collected from the same volume with two sequences with opposite gradients. Phase errors caused by eddy currents are opposite in these two FIDs and can be canceled completely by combining the FIDs. These methods were tested in a phantom. Eddy current distortions were corrected, allowing quantitative measurement of structures such as the -CH = CH- component, which is otherwise undetectable.

  8. Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications

    PubMed Central

    Rifai, Damhuji; Abdalla, Ahmed N.; Ali, Kharudin; Razali, Ramdan

    2016-01-01

    Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper. PMID:26927123

  9. Giant Magnetoresistance Sensors: A Review on Structures and Non-Destructive Eddy Current Testing Applications.

    PubMed

    Rifai, Damhuji; Abdalla, Ahmed N; Ali, Kharudin; Razali, Ramdan

    2016-02-26

    Non-destructive eddy current testing (ECT) is widely used to examine structural defects in ferromagnetic pipe in the oil and gas industry. Implementation of giant magnetoresistance (GMR) sensors as magnetic field sensors to detect the changes of magnetic field continuity have increased the sensitivity of eddy current techniques in detecting the material defect profile. However, not many researchers have described in detail the structure and issues of GMR sensors and their application in eddy current techniques for nondestructive testing. This paper will describe the implementation of GMR sensors in non-destructive testing eddy current testing. The first part of this paper will describe the structure and principles of GMR sensors. The second part outlines the principles and types of eddy current testing probe that have been studied and developed by previous researchers. The influence of various parameters on the GMR measurement and a factor affecting in eddy current testing will be described in detail in the third part of this paper. Finally, this paper will discuss the limitations of coil probe and compensation techniques that researchers have applied in eddy current testing probes. A comprehensive review of previous studies on the application of GMR sensors in non-destructive eddy current testing also be given at the end of this paper.

  10. Use of eddy current mixes to solve a weld examination application

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ward, R.C.; LaBoissonniere, A.

    1995-12-31

    The augmentation of typical nondestructive (i.e., ultrasound) weld inspection techniques by the use of eddy current tools may significantly enhance the quality and reliability of weld inspections. One recent example is the development of an eddy current technique for use in the examination of BWR core shroud welds, where multi-frequency mixes are used to eliminate signals coming from the weld material so that the examination of the heat affected zone is enhanced. An analysis tool most commonly associated with ultrasound examinations, the C-Scan based on gated information, may be implemented with eddy current data to enhance analysis.

  11. Efficacy of Distortion Correction on Diffusion Imaging: Comparison of FSL Eddy and Eddy_Correct Using 30 and 60 Directions Diffusion Encoding

    PubMed Central

    Yamada, Haruyasu; Abe, Osamu; Shizukuishi, Takashi; Kikuta, Junko; Shinozaki, Takahiro; Dezawa, Ko; Nagano, Akira; Matsuda, Masayuki; Haradome, Hiroki; Imamura, Yoshiki

    2014-01-01

    Diffusion imaging is a unique noninvasive tool to detect brain white matter trajectory and integrity in vivo. However, this technique suffers from spatial distortion and signal pileup or dropout originating from local susceptibility gradients and eddy currents. Although there are several methods to mitigate these problems, most techniques can be applicable either to susceptibility or eddy-current induced distortion alone with a few exceptions. The present study compared the correction efficiency of FSL tools, “eddy_correct” and the combination of “eddy” and “topup” in terms of diffusion-derived fractional anisotropy (FA). The brain diffusion images were acquired from 10 healthy subjects using 30 and 60 directions encoding schemes based on the electrostatic repulsive forces. For the 30 directions encoding, 2 sets of diffusion images were acquired with the same parameters, except for the phase-encode blips which had opposing polarities along the anteroposterior direction. For the 60 directions encoding, non–diffusion-weighted and diffusion-weighted images were obtained with forward phase-encoding blips and non–diffusion-weighted images with the same parameter, except for the phase-encode blips, which had opposing polarities. FA images without and with distortion correction were compared in a voxel-wise manner with tract-based spatial statistics. We showed that images corrected with eddy and topup possessed higher FA values than images uncorrected and corrected with eddy_correct with trilinear (FSL default setting) or spline interpolation in most white matter skeletons, using both encoding schemes. Furthermore, the 60 directions encoding scheme was superior as measured by increased FA values to the 30 directions encoding scheme, despite comparable acquisition time. This study supports the combination of eddy and topup as a superior correction tool in diffusion imaging rather than the eddy_correct tool, especially with trilinear interpolation, using 60

  12. Sensor Fusion Techniques for Phased-Array Eddy Current and Phased-Array Ultrasound Data

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Arrowood, Lloyd F.

    Sensor (or Data) fusion is the process of integrating multiple data sources to produce more consistent, accurate and comprehensive information than is provided by a single data source. Sensor fusion may also be used to combine multiple signals from a single modality to improve the performance of a particular inspection technique. Industrial nondestructive testing may utilize multiple sensors to acquire inspection data depending upon the object under inspection and the anticipated types of defects that can be identified. Sensor fusion can be performed at various levels of signal abstraction with each having its strengths and weaknesses. A multimodal data fusionmore » strategy first proposed by Heideklang and Shokouhi that combines spatially scattered detection locations to improve detection performance of surface-breaking and near-surface cracks in ferromagnetic metals is shown using a surface inspection example and is then extended for volumetric inspections. Utilizing data acquired from an Olympus Omniscan MX2 from both phased array eddy current and ultrasound probes on test phantoms, single and multilevel fusion techniques are employed to integrate signals from the two modalities. Preliminary results demonstrate how confidence in defect identification and interpretation benefit from sensor fusion techniques. Lastly, techniques for integrating data into radiographic and volumetric imagery from computed tomography are described and results are presented.« less

  13. Forest Ecosystem respiration estimated from eddy covariance and chamber measurements under high turbulence and substantial tree mortality from bark beetles

    USGS Publications Warehouse

    Speckman, Heather N.; Frank, John M.; Bradford, John B.; Miles, Brianna L.; Massman, William J.; Parton, William J.; Ryan, Michael G.

    2015-01-01

    Eddy covariance nighttime fluxes are uncertain due to potential measurement biases. Many studies report eddy covariance nighttime flux lower than flux from extrapolated chamber measurements, despite corrections for low turbulence. We compared eddy covariance and chamber estimates of ecosystem respiration at the GLEES Ameriflux site over seven growing seasons under high turbulence (summer night mean friction velocity (u*) = 0.7 m s−1), during which bark beetles killed or infested 85% of the aboveground respiring biomass. Chamber-based estimates of ecosystem respiration during the growth season, developed from foliage, wood and soil CO2 efflux measurements, declined 35% after 85% of the forest basal area had been killed or impaired by bark beetles (from 7.1 ±0.22 μmol m−2 s−1 in 2005 to 4.6 ±0.16 μmol m−2 s−1 in 2011). Soil efflux remained at ~3.3 μmol m−2 s−1 throughout the mortality, while the loss of live wood and foliage and their respiration drove the decline of the chamber estimate. Eddy covariance estimates of fluxes at night remained constant over the same period, ~3.0 μmol m−2 s−1 for both 2005 (intact forest) and 2011 (85% basal area killed or impaired). Eddy covariance fluxes were lower than chamber estimates of ecosystem respiration (60% lower in 2005, and 32% in 2011), but the mean night estimates from the two techniques were correlated within a year (r2 from 0.18-0.60). The difference between the two techniques was not the result of inadequate turbulence, because the results were robust to a u* filter of > 0.7 m s−1. The decline in the average seasonal difference between the two techniques was strongly correlated with overstory leaf area (r2=0.92). The discrepancy between methods of respiration estimation should be resolved to have confidence in ecosystem carbon flux estimates.

  14. Annular modes and apparent eddy feedbacks in the Southern Hemisphere

    NASA Astrophysics Data System (ADS)

    Byrne, Nicholas J.; Shepherd, Theodore G.; Woollings, Tim; Plumb, R. Alan

    2016-04-01

    Lagged correlation analysis is often used to infer intraseasonal dynamical effects but is known to be affected by nonstationarity. We highlight a pronounced quasi 2 year peak in the anomalous zonal wind and eddy momentum flux convergence power spectra in the Southern Hemisphere, which is prima facie evidence for nonstationarity. We then investigate the consequences of this nonstationarity for the Southern Annular Mode and for eddy momentum flux convergence. We argue that positive lagged correlations previously attributed to the existence of an eddy feedback are more plausibly attributed to nonstationary interannual variability external to any potential feedback process in the midlatitude troposphere. The findings have implications for the diagnosis of feedbacks in both models and reanalysis data as well as for understanding the mechanisms underlying variations in the zonal wind.

  15. Annular modes and apparent eddy feedbacks in the Southern Hemisphere.

    PubMed

    Byrne, Nicholas J; Shepherd, Theodore G; Woollings, Tim; Plumb, R Alan

    2016-04-28

    Lagged correlation analysis is often used to infer intraseasonal dynamical effects but is known to be affected by nonstationarity. We highlight a pronounced quasi 2 year peak in the anomalous zonal wind and eddy momentum flux convergence power spectra in the Southern Hemisphere, which is prima facie evidence for nonstationarity. We then investigate the consequences of this nonstationarity for the Southern Annular Mode and for eddy momentum flux convergence. We argue that positive lagged correlations previously attributed to the existence of an eddy feedback are more plausibly attributed to nonstationary interannual variability external to any potential feedback process in the midlatitude troposphere. The findings have implications for the diagnosis of feedbacks in both models and reanalysis data as well as for understanding the mechanisms underlying variations in the zonal wind.

  16. Casimir Interaction from Magnetically Coupled Eddy Currents

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Intravaia, Francesco; Henkel, Carsten

    2009-09-25

    We study the quantum and thermal fluctuations of eddy (Foucault) currents in thick metallic plates. A Casimir interaction between two plates arises from the coupling via quasistatic magnetic fields. As a function of distance, the relevant eddy current modes cross over from a quantum to a thermal regime. These modes alone reproduce previously discussed thermal anomalies of the electromagnetic Casimir interaction between good conductors. In particular, they provide a physical picture for the Casimir entropy whose nonzero value at zero temperature arises from a correlated, glassy state.

  17. Evaluation of scale-aware subgrid mesoscale eddy models in a global eddy-rich model

    NASA Astrophysics Data System (ADS)

    Pearson, Brodie; Fox-Kemper, Baylor; Bachman, Scott; Bryan, Frank

    2017-07-01

    Two parameterizations for horizontal mixing of momentum and tracers by subgrid mesoscale eddies are implemented in a high-resolution global ocean model. These parameterizations follow on the techniques of large eddy simulation (LES). The theory underlying one parameterization (2D Leith due to Leith, 1996) is that of enstrophy cascades in two-dimensional turbulence, while the other (QG Leith) is designed for potential enstrophy cascades in quasi-geostrophic turbulence. Simulations using each of these parameterizations are compared with a control simulation using standard biharmonic horizontal mixing.Simulations using the 2D Leith and QG Leith parameterizations are more realistic than those using biharmonic mixing. In particular, the 2D Leith and QG Leith simulations have more energy in resolved mesoscale eddies, have a spectral slope more consistent with turbulence theory (an inertial enstrophy or potential enstrophy cascade), have bottom drag and vertical viscosity as the primary sinks of energy instead of lateral friction, and have isoneutral parameterized mesoscale tracer transport. The parameterization choice also affects mass transports, but the impact varies regionally in magnitude and sign.

  18. Method and apparatus for correcting eddy current signal voltage for temperature effects

    DOEpatents

    Kustra, Thomas A.; Caffarel, Alfred J.

    1990-01-01

    An apparatus and method for measuring physical characteristics of an electrically conductive material by the use of eddy-current techniques and compensating measurement errors caused by changes in temperature includes a switching arrangement connected between primary and reference coils of an eddy-current probe which allows the probe to be selectively connected between an eddy current output oscilloscope and a digital ohm-meter for measuring the resistances of the primary and reference coils substantially at the time of eddy current measurement. In this way, changes in resistance due to temperature effects can be completely taken into account in determining the true error in the eddy current measurement. The true error can consequently be converted into an equivalent eddy current measurement correction.

  19. High resolution eddy current microscopy

    NASA Astrophysics Data System (ADS)

    Lantz, M. A.; Jarvis, S. P.; Tokumoto, H.

    2001-01-01

    We describe a sensitive scanning force microscope based technique for measuring local variations in resistivity by monitoring changes in the eddy current induced damping of a cantilever with a magnetic tip oscillating above a conducting sample. To achieve a high sensitivity, we used a cantilever with an FeNdBLa particle mounted on the tip. Resistivity measurements are demonstrated on a silicon test structure with a staircase doping profile. Regions with resistivities of 0.0013, 0.0041, and 0.022 Ω cm are clearly resolved with a lateral resolution of approximately 180 nm. For this range of resistivities, the eddy current induced damping is found to depend linearly on the sample resistivity.

  20. System for evaluating weld quality using eddy currents

    DOEpatents

    Todorov, Evgueni I.; Hay, Jacob

    2017-12-12

    Electromagnetic and eddy current techniques for fast automated real-time and near real-time inspection and monitoring systems for high production rate joining processes. An eddy current system, array and method for the fast examination of welds to detect anomalies such as missed seam (MS) and lack of penetration (LOP) the system, array and methods capable of detecting and sizing surface and slightly subsurface flaws at various orientations in connection with at least the first and second weld pass.

  1. Ingredients of the Eddy Soup: A Geometric Decomposition of Eddy-Mean Flow Interactions

    NASA Astrophysics Data System (ADS)

    Waterman, S.; Lilly, J. M.

    2014-12-01

    Understanding eddy-mean flow interactions is a long-standing problem in geophysical fluid dynamics with modern relevance to the task of representing eddy effects in coarse resolution models while preserving their dependence on the underlying dynamics of the flow field. Exploiting the recognition that the velocity covariance matrix/eddy stress tensor that describes eddy fluxes, also encodes information about eddy size, shape and orientation through its geometric representation in the form of the so-called variance ellipse, suggests a potentially fruitful way forward. Here we present a new framework that describes eddy-mean flow interactions in terms of a geometric description of the eddy motion, and illustrate it with an application to an unstable jet. Specifically we show that the eddy vorticity flux divergence F, a key dynamical quantity describing the average effect of fluctuations on the time-mean flow, may be decomposed into two components with distinct geometric interpretations: 1. variations in variance ellipse orientation; and 2. variations in the anisotropic part of the eddy kinetic energy, a function of the variance ellipse size and shape. Application of the divergence theorem shows that F integrated over a region is explained entirely by variations in these two quantities around the region's periphery. This framework has the potential to offer new insights into eddy-mean flow interactions in a number of ways. It identifies the ingredients of the eddy motion that have a mean flow forcing effect, it links eddy effects to spatial patterns of variance ellipse geometry that can suggest the mechanisms underpinning these effects, and finally it illustrates the importance of resolving eddy shape and orientation, and not just eddy size/energy, to accurately represent eddy feedback effects. These concepts will be both discussed and illustrated.

  2. Local atmospheric response to warm mesoscale ocean eddies in the Kuroshio-Oyashio Confluence region.

    PubMed

    Sugimoto, Shusaku; Aono, Kenji; Fukui, Shin

    2017-09-19

    In the extratropical regions, surface winds enhance upward heat release from the ocean to atmosphere, resulting in cold surface ocean: surface ocean temperature is negatively correlated with upward heat flux. However, in the western boundary currents and eddy-rich regions, the warmer surface waters compared to surrounding waters enhance upward heat release-a positive correlation between upward heat release and surface ocean temperature, implying that the ocean drives the atmosphere. The atmospheric response to warm mesoscale ocean eddies with a horizontal extent of a few hundred kilometers remains unclear because of a lack of observations. By conducting regional atmospheric model experiments, we show that, in the Kuroshio-Oyashio Confluence region, wintertime warm eddies heat the marine atmospheric boundary layer (MABL), and accelerate westerly winds in the near-surface atmosphere via the vertical mixing effect, leading to wind convergence around the eastern edge of eddies. The warm-eddy-induced convergence forms local ascending motion where convective precipitation is enhanced, providing diabatic heating to the atmosphere above MABL. Our results indicate that warm eddies affect not only near-surface atmosphere but also free atmosphere, and possibly synoptic atmospheric variability. A detailed understanding of warm eddy-atmosphere interaction is necessary to improve in weather and climate projections.

  3. Role of eddy pumping in enhancing primary production in the ocean

    NASA Technical Reports Server (NTRS)

    Falkowski, Paul G.; Kolber, Zbigniew; Ziemann, David; Bienfang, Paul K.

    1991-01-01

    Eddy pumping is considered to explain the disparity between geochemical estimates and biological measurements of exported production. Episodic nutrient injections from the ocean into the photic zone can be generated by eddy pumping, which biological measurements cannot sample accurately. The enhancement of production is studied with respect to a cyclonic eddy in the subtropical Pacific. A pump-and-probe fluorimeter generates continuous vertical profiles of primary productivity from which the contributions of photochemical and nonphotochemical processes to fluorescence are derived. A significant correlation is observed between the fluorescence measurements and radiocarbon measurements. The results indicate that eddy pumping has an important effect on phytoplankton production and that this production is near the maximum relative specific growth rates. Based on the production enhancement observed in this case, eddy pumping increases total primary production by only 20 percent and does not account for all enhancement.

  4. An avenue of eddies: Quantifying the biophysical properties of mesoscale eddies in the Tasman Sea

    NASA Astrophysics Data System (ADS)

    Everett, J. D.; Baird, M. E.; Oke, P. R.; Suthers, I. M.

    2012-08-01

    The Tasman Sea is unique - characterised by a strong seasonal western boundary current that breaks down into a complicated field of mesoscale eddies almost immediately after separating from the coast. Through a 16-year analysis of Tasman Sea eddies, we identify a region along the southeast Australian coast which we name ‘Eddy Avenue’ where eddies have higher sea level anomalies, faster rotation and greater sea surface temperature and chlorophyll a anomalies. The density of cyclonic and anticyclonic eddies within Eddy Avenue is 23% and 16% higher respectively than the broader Tasman Sea. We find that Eddy Avenue cyclonic and anticyclonic eddies have more strongly differentiated biological properties than those of the broader Tasman Sea, as a result of larger anticyclonic eddies formed from Coral Sea water depressing chl. a concentrations, and for coastal cyclonic eddies due to the entrainment of nutrient-rich shelf waters. Cyclonic eddies within Eddy Avenue have almost double the chlorophyll a (0.35 mg m-3) of anticyclonic eddies (0.18 mg m-3). The average chlorophyll a concentration for cyclonic eddies is 16% higher in Eddy Avenue and 28% lower for anticyclonic eddies when compared to the Tasman Sea. With a strengthening East Australian Current, the propagation of these eddies will have significant implications for heat transport and the entrainment and connectivity of plankton and larval fish populations.

  5. Large-Eddy Atmosphere-Land-Surface Modelling over Heterogeneous Surfaces: Model Development and Comparison with Measurements

    NASA Astrophysics Data System (ADS)

    Shao, Yaping; Liu, Shaofeng; Schween, Jan H.; Crewell, Susanne

    2013-08-01

    A model is developed for the large-eddy simulation (LES) of heterogeneous atmosphere and land-surface processes. This couples a LES model with a land-surface scheme. New developments are made to the land-surface scheme to ensure the adequate representation of atmosphere-land-surface transfers on the large-eddy scale. These include, (1) a multi-layer canopy scheme; (2) a method for flux estimates consistent with the large-eddy subgrid closure; and (3) an appropriate soil-layer configuration. The model is then applied to a heterogeneous region with 60-m horizontal resolution and the results are compared with ground-based and airborne measurements. The simulated sensible and latent heat fluxes are found to agree well with the eddy-correlation measurements. Good agreement is also found in the modelled and observed net radiation, ground heat flux, soil temperature and moisture. Based on the model results, we study the patterns of the sensible and latent heat fluxes, how such patterns come into existence, and how large eddies propagate and destroy land-surface signals in the atmosphere. Near the surface, the flux and land-use patterns are found to be closely correlated. In the lower boundary layer, small eddies bearing land-surface signals organize and develop into larger eddies, which carry the signals to considerably higher levels. As a result, the instantaneous flux patterns appear to be unrelated to the land-use patterns, but on average, the correlation between them is significant and persistent up to about 650 m. For a given land-surface type, the scatter of the fluxes amounts to several hundred W { m }^{-2}, due to (1) large-eddy randomness; (2) rapid large-eddy and surface feedback; and (3) local advection related to surface heterogeneity.

  6. New gap-filling and partitioning technique for H2O eddy fluxes measured over forests

    NASA Astrophysics Data System (ADS)

    Kang, Minseok; Kim, Joon; Malla Thakuri, Bindu; Chun, Junghwa; Cho, Chunho

    2018-01-01

    The continuous measurement of H2O fluxes using the eddy covariance (EC) technique is still challenging for forests because of large amounts of wet canopy evaporation (EWC), which occur during and following rain events when the EC systems rarely work correctly. We propose a new gap-filling and partitioning technique for the H2O fluxes: a model-statistics hybrid (MSH) method. It enables the recovery of the missing EWC in the traditional gap-filling method and the partitioning of the evapotranspiration (ET) into transpiration and (wet canopy) evaporation. We tested and validated the new method using the data sets from two flux towers, which are located at forests in hilly and complex terrains. The MSH reasonably recovered the missing EWC of 16-41 mm yr-1 and separated it from the ET (14-23 % of the annual ET). Additionally, we illustrated certain advantages of the proposed technique which enable us to understand better how ET responds to environmental changes and how the water cycle is connected to the carbon cycle in a forest ecosystem.

  7. Effects of Mesoscale Eddies in the Active Mixed Layer: Test of the Parametrisation in Eddy Resolving Simulations

    NASA Technical Reports Server (NTRS)

    Luneva, M. V.; Clayson, C. A.; Dubovikov, Mikhail

    2015-01-01

    In eddy resolving simulations, we test a mixed layer mesoscale parametrisation, developed recently by Canuto and Dubovikov [Ocean Model., 2011, 39, 200-207]. With no adjustable parameters, the parametrisation yields the horizontal and vertical mesoscale fluxes in terms of coarse-resolution fields and eddy kinetic energy (EKE). We compare terms of the parametrisation diagnosed from coarse-grained fields with the eddy mesoscale fluxes diagnosed directly from the high resolution model. An expression for the EKE in terms of mean fields has also been found to get a closed parametrisation in terms of the mean fields only. In 40 numerical experiments we simulated two types of flows: idealised flows driven by baroclinic instabilities only, and more realistic flows, driven by wind and surface fluxes as well as by inflow-outflow. The diagnosed quasi-instantaneous horizontal and vertical mesoscale buoyancy fluxes (averaged over 1-2 degrees and 10 days) demonstrate a strong scatter typical for turbulent flows, however, the fluxes are positively correlated with the parametrisation with higher (0.5-0.74) correlations at the experiments with larger baroclinic radius Rossby. After being averaged over 3-4 months, diffusivities diagnosed from the eddy resolving simulations are consistent with the parametrisation for a broad range of parameters. Diagnosed vertical mesoscale fluxes restratify mixed layer and are in a good agreement with the parametrisation unless vertical turbulent mixing in the upper layer becomes strong enough in comparison with mesoscale advection. In the latter case, numerical simulations demonstrate that the deviation of the fluxes from the parametrisation is controlled by dimensionless parameter estimating the ratio of vertical turbulent mixing term to mesoscale advection. An analysis using a modified omega-equation reveals that the effects of the vertical mixing of vorticity is responsible for the two-three fold amplification of vertical mesoscale flux

  8. Large Eddy Simulations using oodlesDST

    DTIC Science & Technology

    2016-01-01

    Research Agency DST-Group-TR-3205 ABSTRACT The oodlesDST code is based on OpenFOAM software and performs Large Eddy Simulations of......maritime platforms using a variety of simulation techniques. He is currently using OpenFOAM software to perform both Reynolds Averaged Navier-Stokes

  9. Unwrapping eddy current compensation: improved compensation of eddy current induced baseline shifts in high-resolution phase-contrast MRI at 9.4 Tesla.

    PubMed

    Espe, Emil K S; Zhang, Lili; Sjaastad, Ivar

    2014-10-01

    Phase-contrast MRI (PC-MRI) is a versatile tool allowing evaluation of in vivo motion, but is sensitive to eddy current induced phase offsets, causing errors in the measured velocities. In high-resolution PC-MRI, these offsets can be sufficiently large to cause wrapping in the baseline phase, rendering conventional eddy current compensation (ECC) inadequate. The purpose of this study was to develop an improved ECC technique (unwrapping ECC) able to handle baseline phase discontinuities. Baseline phase discontinuities are unwrapped by minimizing the spatiotemporal standard deviation of the static-tissue phase. Computer simulations were used for demonstrating the theoretical foundation of the proposed technique. The presence of baseline wrapping was confirmed in high-resolution myocardial PC-MRI of a normal rat heart at 9.4 Tesla (T), and the performance of unwrapping ECC was compared with conventional ECC. Areas of phase wrapping in static regions were clearly evident in high-resolution PC-MRI. The proposed technique successfully eliminated discontinuities in the baseline, and resulted in significantly better ECC than the conventional approach. We report the occurrence of baseline phase wrapping in PC-MRI, and provide an improved ECC technique capable of handling its presence. Unwrapping ECC offers improved correction of eddy current induced baseline shifts in high-resolution PC-MRI. Copyright © 2013 Wiley Periodicals, Inc.

  10. Comprehensive comparison of gap filling techniques for eddy covariance net carbon fluxes

    NASA Astrophysics Data System (ADS)

    Moffat, A. M.; Papale, D.; Reichstein, M.; Hollinger, D. Y.; Richardson, A. D.; Barr, A. G.; Beckstein, C.; Braswell, B. H.; Churkina, G.; Desai, A. R.; Falge, E.; Gove, J. H.; Heimann, M.; Hui, D.; Jarvis, A. J.; Kattge, J.; Noormets, A.; Stauch, V. J.

    2007-12-01

    Review of fifteen techniques for estimating missing values of net ecosystem CO2 exchange (NEE) in eddy covariance time series and evaluation of their performance for different artificial gap scenarios based on a set of ten benchmark datasets from six forested sites in Europe. The goal of gap filling is the reproduction of the NEE time series and hence this present work focuses on estimating missing NEE values, not on editing or the removal of suspect values in these time series due to systematic errors in the measurements (e.g. nighttime flux, advection). The gap filling was examined by generating fifty secondary datasets with artificial gaps (ranging in length from single half-hours to twelve consecutive days) for each benchmark dataset and evaluating the performance with a variety of statistical metrics. The performance of the gap filling varied among sites and depended on the level of aggregation (native half- hourly time step versus daily), long gaps were more difficult to fill than short gaps, and differences among the techniques were more pronounced during the day than at night. The non-linear regression techniques (NLRs), the look-up table (LUT), marginal distribution sampling (MDS), and the semi-parametric model (SPM) generally showed good overall performance. The artificial neural network based techniques (ANNs) were generally, if only slightly, superior to the other techniques. The simple interpolation technique of mean diurnal variation (MDV) showed a moderate but consistent performance. Several sophisticated techniques, the dual unscented Kalman filter (UKF), the multiple imputation method (MIM), the terrestrial biosphere model (BETHY), but also one of the ANNs and one of the NLRs showed high biases which resulted in a low reliability of the annual sums, indicating that additional development might be needed. An uncertainty analysis comparing the estimated random error in the ten benchmark datasets with the artificial gap residuals suggested that the

  11. Southern Ocean eddy compensation in a forced eddy-resolving GCM

    NASA Astrophysics Data System (ADS)

    Bruun Poulsen, Mads; Jochum, Markus; Eden, Carsten; Nuterman, Roman

    2017-04-01

    Contemporary eddy-resolving model studies have demonstrated that the common parameterisation of isopycnal mixing in the ocean is subject to limitations in the Southern Ocean where the mesoscale eddies are of leading order importance to the dynamics. We here present forced simulations from the Community Earth System Model on a global {1/10}° and 1° horizontal grid, the latter employing an eddy parameterisation, where the strength of the zonal wind stress south of 25°S has been varied. With a 50% zonally symmetric increase of the wind stress, we show that the two models arrive at two radically different solutions in terms of the large-scale circulation, with an increase of the deep inflow of water to the Southern Ocean at 40°S by 50% in the high resolution model against 20% at coarse resolution. Together with a weaker vertical displacement of the pycnocline in the 1° model, these results suggest that the parameterised eddies have an overly strong compensating effect on the water mass transformation compared to the explicit eddies. Implications for eddy mixing parameterisations will be discussed.

  12. Eddy current heating in magnetic refrigerators

    NASA Technical Reports Server (NTRS)

    Kittel, Peter

    1990-01-01

    Eddy current heating can be a significant source of parasitic heating in low temperature magnetic refrigerators. To study this problem a technique to approximate the heating due to eddy currents has been developed. A formula is presented for estimating the heating within a variety of shapes commonly found in magnetic refrigerators. These shapes include circular, square, and rectangular rods; cylindrical and split cylindrical shells; wire loops; and 'coil foil. One set of components evaluated are different types of thermal radiation shields. This comparison shows that a simple split shield is almost as effective (only 23 percent more heating) as using a shield, with the same axial thermal conductivity, made of 'coil foil'.

  13. Optical correlation techniques in fluid dynamics

    NASA Astrophysics Data System (ADS)

    Schätzel, K.; Schulz-Dubois, E. O.; Vehrenkamp, R.

    1981-04-01

    Three flow measurement techniques make use of fast digital correlators. The most widely spread is photon correlation velocimetry using crossed laser beams, and detecting Doppler shifted light scattered by small particles in the flow. Depending on the processing of the photon correlation output, this technique yields mean velocity, turbulence level, and even the detailed probability distribution of one velocity component. An improved data processing scheme is demonstrated on laminar vortex flow in a curved channel. In the second method, rate correlation based upon threshold crossings of a high pass filtered laser Doppler signal can be used to obtain velocity correlation functions. The most powerful set-up developed in our laboratory uses a phase locked loop type tracker and a multibit correlator to analyze time-dependent Taylor vortex flow. With two optical systems and trackers, cross-correlation functions reveal phase relations between different vortices. The last method makes use of refractive index fluctuations (eg in two phase flows) instead of scattering particles. Interferometry with bidirectional counting, and digital correlation and probability analysis, constitutes a new quantitative technique related to classical Schlieren methods. Measurements on a mixing flow of heated and cold air contribute new ideas to the theory of turbulent random phase screens.

  14. Large Eddy Simulation of a Film Cooling Technique with a Plenum

    NASA Astrophysics Data System (ADS)

    Dharmarathne, Suranga; Sridhar, Narendran; Araya, Guillermo; Castillo, Luciano; Parameswaran, Sivapathasund

    2012-11-01

    Factors that affect the film cooling performance have been categorized into three main groups: (i) coolant & mainstream conditions, (ii) hole geometry & configuration, and (iii) airfoil geometry Bogard et al. (2006). The present study focuses on the second group of factors, namely, the modeling of coolant hole and the plenum. It is required to simulate correct physics of the problem to achieve more realistic numerical results. In this regard, modeling of cooling jet hole and the plenum chamber is highly important Iourokina et al. (2006). Substitution of artificial boundary conditions instead of correct plenum design would yield unrealistic results Iourokina et al. (2006). This study attempts to model film cooling technique with a plenum using a Large Eddy Simulation.Incompressible coolant jet ejects to the surface of the plate at an angle of 30° where it meets compressible turbulent boundary layer which simulates the turbine inflow conditions. Dynamic multi-scale approach Araya (2011) is introduced to prescribe turbulent inflow conditions. Simulations are carried out for two different blowing ratios and film cooling effectiveness is calculated for both cases. Results obtained from LES will be compared with experimental results.

  15. An Eddy Current Testing Platform System for Pipe Defect Inspection Based on an Optimized Eddy Current Technique Probe Design

    PubMed Central

    Rifai, Damhuji; Abdalla, Ahmed N.; Razali, Ramdan; Ali, Kharudin; Faraj, Moneer A.

    2017-01-01

    The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient. PMID:28335399

  16. An Eddy Current Testing Platform System for Pipe Defect Inspection Based on an Optimized Eddy Current Technique Probe Design.

    PubMed

    Rifai, Damhuji; Abdalla, Ahmed N; Razali, Ramdan; Ali, Kharudin; Faraj, Moneer A

    2017-03-13

    The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient.

  17. Turbulent fluxes by "Conditional Eddy Sampling"

    NASA Astrophysics Data System (ADS)

    Siebicke, Lukas

    2015-04-01

    for the field (one to two orders of magnitude lower compared to current closed-path laser based eddy covariance systems). Potential applications include fluxes of CO2, CH4, N2O, VOCs and other tracers. Finally we assess the flux accuracy of the Conditional Eddy Sampling (CES) approach as in our real implementation relative to alternative techniques including eddy covariance (EC) and relaxed eddy accumulation (REA). We further quantify various sources of instrument and method specific measurement errors. This comparison uses real measurements of 20 Hz turbulent time series of 3D wind velocity, sonic temperature and CO2 mixing ratio over a mixed decidious forest at the 'ICOS' flux tower site 'Hainich', Germany. Results from a simulation using real wind and CO2 timeseries from the Hainich site from 30 April to 3 November 2014 and real instrument performance suggest that the maximum flux estimates error (50% and 75% error quantiles) from Conditional Eddy Sampling (CES) relative to the true flux is 1.3% and 10%, respectively for monthly net fluxes, 1.6% and 7%, respectively for daily net fluxes and 8% and 35%, respectively for 30-minute CO2 flux estimates. Those results from CES are promising and outperform our REA estimates by about a factor of 50 assuming REA with constant b value. Results include flux time series from the EC, CES and REA approaches from 30-min to annual resolution.

  18. Quantification and Compensation of Eddy-Current-Induced Magnetic Field Gradients

    PubMed Central

    Spees, William M.; Buhl, Niels; Sun, Peng; Ackerman, Joseph J.H.; Neil, Jeffrey J.; Garbow, Joel R.

    2011-01-01

    Two robust techniques for quantification and compensation of eddy-current-induced magnetic-field gradients and static magnetic-field shifts (ΔB0) in MRI systems are described. Purpose-built 1-D or 6-point phantoms are employed. Both procedures involve measuring the effects of a prior magnetic-field-gradient test pulse on the phantom’s free induction decay (FID). Phantom-specific analysis of the resulting FID data produces estimates of the time-dependent, eddy-current-induced magnetic field gradient(s) and ΔB0 shift. Using Bayesian methods, the time dependencies of the eddy-current-induced decays are modeled as sums of exponentially decaying components, each defined by an amplitude and time constant. These amplitudes and time constants are employed to adjust the scanner’s gradient pre-emphasis unit and eliminate undesirable eddy-current effects. Measurement with the six-point sample phantom allows for simultaneous, direct estimation of both on-axis and cross-term eddy-current-induced gradients. The two methods are demonstrated and validated on several MRI systems with actively-shielded gradient coil sets. PMID:21764614

  19. Quantification and compensation of eddy-current-induced magnetic-field gradients.

    PubMed

    Spees, William M; Buhl, Niels; Sun, Peng; Ackerman, Joseph J H; Neil, Jeffrey J; Garbow, Joel R

    2011-09-01

    Two robust techniques for quantification and compensation of eddy-current-induced magnetic-field gradients and static magnetic-field shifts (ΔB0) in MRI systems are described. Purpose-built 1-D or six-point phantoms are employed. Both procedures involve measuring the effects of a prior magnetic-field-gradient test pulse on the phantom's free induction decay (FID). Phantom-specific analysis of the resulting FID data produces estimates of the time-dependent, eddy-current-induced magnetic field gradient(s) and ΔB0 shift. Using Bayesian methods, the time dependencies of the eddy-current-induced decays are modeled as sums of exponentially decaying components, each defined by an amplitude and time constant. These amplitudes and time constants are employed to adjust the scanner's gradient pre-emphasis unit and eliminate undesirable eddy-current effects. Measurement with the six-point sample phantom allows for simultaneous, direct estimation of both on-axis and cross-term eddy-current-induced gradients. The two methods are demonstrated and validated on several MRI systems with actively-shielded gradient coil sets. Copyright © 2011 Elsevier Inc. All rights reserved.

  20. Analysis and numerical modelling of eddy current damper for vibration problems

    NASA Astrophysics Data System (ADS)

    Irazu, L.; Elejabarrieta, M. J.

    2018-07-01

    This work discusses a contactless eddy current damper, which is used to attenuate structural vibration. Eddy currents can remove energy from dynamic systems without any contact and, thus, without adding mass or modifying the rigidity of the structure. An experimental modal analysis of a cantilever beam in the absence of and under a partial magnetic field is conducted in the bandwidth of 01 kHz. The results show that the eddy current phenomenon can attenuate the vibration of the entire structure without modifying the natural frequencies or the mode shapes of the structure itself. In this study, a new inverse method to numerically determine the dynamic properties of the contactless eddy current damper is proposed. The proposed inverse method and the eddy current model based on a lineal viscous force are validated by a practical application. The numerically obtained transfer function correlates with the experimental one, thus showing good agreement in the entire bandwidth of 01 kHz. The proposed method provides an easy and quick tool to model and predict the dynamic behaviour of the contactless eddy current damper, thereby avoiding the use of complex analytical models.

  1. Optical Correlation Techniques In Fluid Dynamics

    NASA Astrophysics Data System (ADS)

    Schatzel, K.; Schulz-DuBois, E. O.; Vehrenkamp, R.

    1981-05-01

    Three flow measurement techniques make use of fast digital correlators. (1) Most widely spread is photon correlation velocimetry using crossed laser beams and detecting Doppler shifted light scattered by small particles in the flow. Depending on the processing of the photon correlogram, this technique yields mean velocity, turbulence level, or even the detailed probability distribution of one velocity component. An improved data processing scheme is demonstrated on laminar vortex flow in a curved channel. (2) Rate correlation based upon threshold crossings of a high pass filtered laser Doppler signal can he used to obtain velocity correlation functions. The most powerful setup developed in our laboratory uses a phase locked loop type tracker and a multibit correlator to analyse time-dependent Taylor vortex flow. With two optical systems and trackers, crosscorrelation functions reveal phase relations between different vortices. (3) Making use of refractive index fluctuations (e. g. in two phase flows) instead of scattering particles, interferometry with bidirectional fringe counting and digital correlation and probability analysis constitute a new quantitative technique related to classical Schlieren methods. Measurements on a mixing flow of heated and cold air contribute new ideas to the theory of turbulent random phase screens.

  2. Mesoscale Eddies in the Northwestern Pacific Ocean: Three-Dimensional Eddy Structures and Heat/Salt Transports

    NASA Astrophysics Data System (ADS)

    Dong, Di; Brandt, Peter; Chang, Ping; Schütte, Florian; Yang, Xiaofeng; Yan, Jinhui; Zeng, Jisheng

    2017-12-01

    The region encompassing the Kuroshio Extension (KE) in the Northwestern Pacific Ocean (25°N-45°N and 130°E-180°E) is one of the most eddy-energetic regions of the global ocean. The three-dimensional structures and transports of mesoscale eddies in this region are comprehensively investigated by combined use of satellite data and Argo profiles. With the allocation of Argo profiles inside detected eddies, the spatial variations of structures of eddy temperature and salinity anomalies are analyzed. The results show that eddies predominantly have subsurface (near-surface) intensified temperature and salinity anomalies south (north) of the KE jet, which is related to different background stratifications between these regions. A new method based on eddy trajectories and the inferred three-dimensional eddy structures is proposed to estimate heat and salt transports by eddy movements in a Lagrangian framework. Spatial distributions of eddy transports are presented over the vicinity of the KE for the first time. The magnitude of eddy-induced meridional heat (freshwater volume) transport is on the order of 0.01 PW (103 m3/s). The eddy heat transport divergence results in an oceanic heat loss south and heat gain north of the KE, thereby reinforcing and counteracting the oceanic heat loss from air-sea fluxes south and north of the KE jet, respectively. It also suggests a poleward heat transport across the KE jet due to eddy propagation.

  3. The Stability of Outcropping Ocean Eddies

    NASA Astrophysics Data System (ADS)

    Paldor, N.; Cohen, Y.; Dvorkin, Y.

    2017-12-01

    In the end of the last century numerous ship-borne observations and linear instability studies have addressed the long life span of meso-scale ocean eddies. These eddies are observed to persist in the ocean for periods of 2-3 years with little deformation. As eddy instabilities occur because Rossby waves in the surrounding (assumed motionless) ocean interact with various waves in the eddy itself, the stability was attributed to some eddy structure that hinders such wave-wave interactions. However, instabilities with growthrates of the order of the inertial period were found in various multilayer models including hypothesized structures and several observed eddy structures. A solution to the difference between instability theory and observed stability was ultimately suggested by relaxing the assumption of a motionless ocean that surrounds the eddy and prescribing the mean flow in the ocean such that it counterbalances the depth changes imposed by the eddy while maintaining a constant PV-ocean. This hypothesis was successfully applied to Gaussian eddies for mathematical simplicity. Yet, the Gaussian eddy has no surface front - thus avoiding instabilities that involve frontal waves - and it disagrees with observation that clearly show that most eddies have surface fronts. Here the constant PV ocean hypothesis is applied to two frontal eddies: constant PV-eddies and solidly rotating eddy. A complete account of the mean flow of the coupled eddy-ocean system is analyzed using a canonical formulation of the gradient balance. The phase speeds of waves in the eddy-ocean system are computed by a shooting method. Both eddies are found to be unstable in motionless ocean, yet in a constant PV-ocean no instabilities are found using the exact same numerical search. While many eddy structures can be hypothesized there are only a handful of physical mechanisms for instability and in these eddies the assumed constant PV-ocean negates many of these physical mechanisms for instability

  4. Toward large eddy simulation of turbulent flow over an airfoil

    NASA Technical Reports Server (NTRS)

    Choi, Haecheon

    1993-01-01

    The flow field over an airfoil contains several distinct flow characteristics, e.g. laminar, transitional, turbulent boundary layer flow, flow separation, unstable free shear layers, and a wake. This diversity of flow regimes taxes the presently available Reynolds averaged turbulence models. Such models are generally tuned to predict a particular flow regime, and adjustments are necessary for the prediction of a different flow regime. Similar difficulties are likely to emerge when the large eddy simulation technique is applied with the widely used Smagorinsky model. This model has not been successful in correctly representing different turbulent flow fields with a single universal constant and has an incorrect near-wall behavior. Germano et al. (1991) and Ghosal, Lund & Moin have developed a new subgrid-scale model, the dynamic model, which is very promising in alleviating many of the persistent inadequacies of the Smagorinsky model: the model coefficient is computed dynamically as the calculation progresses rather than input a priori. The model has been remarkably successful in prediction of several turbulent and transitional flows. We plan to simulate turbulent flow over a '2D' airfoil using the large eddy simulation technique. Our primary objective is to assess the performance of the newly developed dynamic subgrid-scale model for computation of complex flows about aircraft components and to compare the results with those obtained using the Reynolds average approach and experiments. The present computation represents the first application of large eddy simulation to a flow of aeronautical interest and a key demonstration of the capabilities of the large eddy simulation technique.

  5. Development of eddy current microscopy for high resolution electrical conductivity imaging using atomic force microscopy.

    PubMed

    Nalladega, V; Sathish, S; Jata, K V; Blodgett, M P

    2008-07-01

    We present a high resolution electrical conductivity imaging technique based on the principles of eddy current and atomic force microscopy (AFM). An electromagnetic coil is used to generate eddy currents in an electrically conducting material. The eddy currents generated in the conducting sample are detected and measured with a magnetic tip attached to a flexible cantilever of an AFM. The eddy current generation and its interaction with the magnetic tip cantilever are theoretically modeled using monopole approximation. The model is used to estimate the eddy current force between the magnetic tip and the electrically conducting sample. The theoretical model is also used to choose a magnetic tip-cantilever system with appropriate magnetic field and spring constant to facilitate the design of a high resolution electrical conductivity imaging system. The force between the tip and the sample due to eddy currents is measured as a function of the separation distance and compared to the model in a single crystal copper. Images of electrical conductivity variations in a polycrystalline dual phase titanium alloy (Ti-6Al-4V) sample are obtained by scanning the magnetic tip-cantilever held at a standoff distance from the sample surface. The contrast in the image is explained based on the electrical conductivity and eddy current force between the magnetic tip and the sample. The spatial resolution of the eddy current imaging system is determined by imaging carbon nanofibers in a polymer matrix. The advantages, limitations, and applications of the technique are discussed.

  6. Anticyclonic eddies are more productive than cyclonic eddies in subtropical gyres because of winter mixing.

    PubMed

    Dufois, François; Hardman-Mountford, Nick J; Greenwood, Jim; Richardson, Anthony J; Feng, Ming; Matear, Richard J

    2016-05-01

    Mesoscale eddies are ubiquitous features of ocean circulation that modulate the supply of nutrients to the upper sunlit ocean, influencing the rates of carbon fixation and export. The popular eddy-pumping paradigm implies that nutrient fluxes are enhanced in cyclonic eddies because of upwelling inside the eddy, leading to higher phytoplankton production. We show that this view does not hold for a substantial portion of eddies within oceanic subtropical gyres, the largest ecosystems in the ocean. Using space-based measurements and a global biogeochemical model, we demonstrate that during winter when subtropical eddies are most productive, there is increased chlorophyll in anticyclones compared with cyclones in all subtropical gyres (by 3.6 to 16.7% for the five basins). The model suggests that this is a consequence of the modulation of winter mixing by eddies. These results establish a new paradigm for anticyclonic eddies in subtropical gyres and could have important implications for the biological carbon pump and the global carbon cycle.

  7. Energy Cascade Analysis: from Subscale Eddies to Mean Flow

    NASA Astrophysics Data System (ADS)

    Cheikh, Mohamad Ibrahim; Wonnell, Louis; Chen, James

    2017-11-01

    Understanding the energy transfer between eddies and mean flow can provide insights into the energy cascade process. Much work has been done to investigate the energy cascade at the level of the smallest eddies using different numerical techniques derived from the Navier-Stokes equations. These methodologies, however, prove to be computationally inefficient when producing energy spectra for a wide range of length scales. In this regard, Morphing Continuum Theory (MCT) resolves the length-scales issues by assuming the fluid continuum to be composed of inner structures that play the role of subscale eddies. The current study show- cases the capabilities of MCT in capturing the dynamics of energy cascade at the level of subscale eddies, through a supersonic turbulent flow of Mach 2.93 over an 8× compression ramp. Analysis of the results using statistical averaging procedure shows the existence of a statistical coupling of the internal and translational kinetic energy fluctuations with the corresponding rotational kinetic energy of the subscale eddies, indicating a multiscale transfer of energy. The results show that MCT gives a new characterization of the energy cascade within compressible turbulence without the use of excessive computational resources. This material is based upon work supported by the Air Force Office of Scientific Research under Award Number FA9550-17-1-0154.

  8. The eddy cannon

    NASA Astrophysics Data System (ADS)

    Pichevin, Thierry; Nof, Doron

    1996-09-01

    A new nonlinear mechanism for the generation of "Meddies" by a cape is proposed. The essence of the new process is that the flow-force associated with any steady current that curves back on itself around a cape cannot be balanced without generating and shedding eddies. The process is modeled as follows. A westward flowing density current advances along a zonal wall and turns eastward after reaching the edge of the wall (i.e. the Cape of St Vincent). Integration of the steady (and inviscid) momentum equation along the wall gives the long-shore flow-force and shows that, no matter what the details of the turning process are, such a scenario is impossible. It corresponds to an unbalanced flow-force and, therefore, cannot exist. Namely, in an analogy to a rocket, the zonal longshore current forces the entire system to the west. A flow field that can compensate for such a force is westward drifting eddies that push the system to the east. In a similar fashion to the backward push associated with a firing cannon, the westward moving eddies (bullets) balance the integrated momentum of the flow around the cape. Nonlinear solutions are constructed analytically using an approach that enables one to compute the eddies' size and generation frequency without solving for the incredibly complicated details of the generation process itself. The method takes advantage of the fact that, after each eddy is generated, the system returns to its original structure. It is based on the integration of the momentum equation (for periodic flows) over a control volume and a perturbation expansion in ɛ, the ratio between the eddies' westward drift and the parent current speed. It is found that, because of the relatively small size of the Mediterranean eddies, β is not a sufficiently strong mechanism to remove the eddies (from the Cape of St Vincent) at the observed frequency. It is, therefore, concluded that westward advection must also take place. Specifically, it is found that an advection

  9. Non-destructive characterization of SiC coated carbon-carbon composites by multiple techniques

    NASA Astrophysics Data System (ADS)

    Nixon, Thomas D.; Hemstad, Stan N.; Pfeifer, William H.

    SiC coated carbon-carbon composites were evaluated using several non-destructive techniques as a means of quantifying the quality of both the coating and substrate. The techniques employed included dye penetrant infiltration, eddy current measurement, C-scan, and computed tomography (CT). The NDE results were then correlated to oxidation performance and destructive evaluations by electron and optical microscopy.

  10. Eddy energy and shelf interactions in the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Ohlmann, J. Carter; Niiler, P. Peter; Fox, Chad A.; Leben, Robert R.

    2001-02-01

    Sea surface height anomaly data from satellite are continuously available for the entire Gulf of Mexico. Surface current velocities derived from these remotely sensed data are compared with surface velocities from drifting buoys. The comparison shows that satellite altimetry does an excellent job resolving gulf eddies over the shelf rise (depths between ˜200 and 2000 m) if the proper length scale is used. Correlations between altimeter- and drifter-derived velocities are statistically significant (r>0.5) when the surface slope is computed over 125 km, indicating that remotely sensed sea surface height anomaly data can be used to aid the understanding of circulation over the shelf rise. Velocity variance over the shelf rise from the altimetry data shows regions of pronounced eddy energy south of the Mississippi outflow, south of the Texas-Louisiana shelf, and in the northwest and northeast corners of the gulf. These are the same locations where surface drifters are most likely to cross the shelf rise, suggesting gulf eddies promote cross-shore flows. This is clearly exemplified with both warm and cold eddies. Finally, the contribution of gulf eddies and wind stress to changes in the mean circulation are compared. Results indicate that the eddy-generated vorticity flux to the mean flow is greater than the contribution from the surface wind stress curl, especially in the region of the Loop current and along the shelf rise base in the western gulf. Future modeling efforts must not neglect the role of eddies in driving gulf circulation over the shelf rise.

  11. Combined investigation of Eddy current and ultrasonic techniques for composite materials NDE

    NASA Technical Reports Server (NTRS)

    Davis, C. W.; Nath, S.; Fulton, J. P.; Namkung, M.

    1993-01-01

    Advanced composites are not without trade-offs. Their increased designability brings an increase in the complexity of their internal geometry and, as a result, an increase in the number of failure modes associated with a defect. When two or more isotropic materials are combined in a composite, the isotropic material failure modes may also combine. In a laminate, matrix delamination, cracking and crazing, and voids and porosity, will often combine with fiber breakage, shattering, waviness, and separation to bring about ultimate structural failure. This combining of failure modes can result in defect boundaries of different sizes, corresponding to the failure of each structural component. This paper discusses a dual-technology NDE (Non Destructive Evaluation) (eddy current (EC) and ultrasonics (UT)) study of graphite/epoxy (gr/ep) laminate samples. Eddy current and ultrasonic raster (Cscan) imaging were used together to characterize the effects of mechanical impact damage, high temperature thermal damage and various types of inserts in gr/ep laminate samples of various stacking sequences.

  12. Observational evidence of seasonality in the timing of loop current eddy separation

    NASA Astrophysics Data System (ADS)

    Hall, Cody A.; Leben, Robert R.

    2016-12-01

    Observational datasets, reports and analyses over the time period from 1978 through 1992 are reviewed to derive pre-altimetry Loop Current (LC) eddy separation dates. The reanalysis identified 20 separation events in the 15-year record. Separation dates are estimated to be accurate to approximately ± 1.5 months and sufficient to detect statistically significant LC eddy separation seasonality, which was not the case for previously published records because of the misidentification of separation events and their timing. The reanalysis indicates that previously reported LC eddy separation dates, determined for the time period before the advent of continuous altimetric monitoring in the early 1990s, are inaccurate because of extensive reliance on satellite sea surface temperature (SST) imagery. Automated LC tracking techniques are used to derive LC eddy separation dates in three different altimetry-based sea surface height (SSH) datasets over the time period from 1993 through 2012. A total of 28-30 LC eddy separation events were identified in the 20-year record. Variations in the number and dates of eddy separation events are attributed to the different mean sea surfaces and objective-analysis smoothing procedures used to produce the SSH datasets. Significance tests on various altimetry and pre-altimetry/altimetry combined date lists consistently show that the seasonal distribution of separation events is not uniform at the 95% confidence level. Randomization tests further show that the seasonal peak in LC eddy separation events in August and September is highly unlikely to have occurred by chance. The other seasonal peak in February and March is less significant, but possibly indicates two seasons of enhanced probability of eddy separation centered near the spring and fall equinoxes. This is further quantified by objectively dividing the seasonal distribution into two seasons using circular statistical techniques and a k-means clustering algorithm. The estimated

  13. On the cyclonic eddy generation in Panay Strait, Philippines

    NASA Astrophysics Data System (ADS)

    Flament, P. J.; Repollo, C. L. A.; Flores-vidal, X.; Villanoy, C.

    2016-12-01

    High Frequency Doppler Radar (HFDR), shallow pressure gauges and Acoustic Doppler Current Profiler (ADCP) time-series observations during the Philippine Straits Dynamics Experiment (PhilEx) were analyzed to describe the mesoscale currents in Panay Strait, Philippines. Low frequency surface currents inferred from three HFDR (July 2008 { July 2009), revealed a clear seasonal signal in concurrent with the reversal of the Asian monsoon. The mesoscale cyclonic eddy west of Panay Island is generated during the winter northeast (NE) monsoon. This causes changes in the strength, depth and width of the intra-seasonal Panay coastal jet as its eastern limb. Winds from QuikSCAT satellite and from a nearby airport indicate that these flow structures correlate with the strength and direction of the prevailing local wind. An intensive survey of the cyclonic eddy in February 8-9, 2009, obtaining a 24-hour successive cross-shore Conductivity-Temperature- Depth (CTD) sections in conjunction with shipboard ADCP measurements showed a well- developed cyclonic eddy characterized by near-surface velocities reaching 50 cm/s. This observation coincides with the intensification of the wind in between Mindoro and Panay islands generating a positive wind stress curl in the lee of Panay, which in turn induces divergent surface currents. Water column response from the mean transects showed a pronounced signal of upwelling, indicated by the doming of isotherms and isopycnals. A pressure gradient then was sets up, resulting in the spin-up of a cyclonic eddy in geostrophic balance. Evaluation of the surface vorticity balance equation suggests that the wind stress curl via Ekman pumping mechanism provides the necessary input in the formation and evolution of the cyclonic eddy. In particular, the cumulative effect of the wind stress curl plays a key role on the generation of the eddy. The Beta-effect on the other hand may led to propagation of the eddy westward.

  14. Catalina Eddy as revealed by the historical downscaling of reanalysis

    NASA Astrophysics Data System (ADS)

    Kanamitsu, Masao; Yulaeva, Elena; Li, Haiqin; Hong, Song-You

    2013-08-01

    Climatological properties, dynamical and thermodynamical characteristics of the Catalina Eddy are examined from the 61 years NCEP/NCAR Reanalysis downscaled to hourly 10 km resolution. The eddy is identified as a mesoscale cyclonic circulation confined to the Southern California Bight. Pattern correlation of wind direction against the canonical Catalina Eddy is used to extract cases from the downscaled analysis. Validation against published cases and various observations confirmed that the downscaled analysis accurately reproduces Catalina Eddy events. A composite analysis of the initiation phase of the eddy indicates that no apparent large-scale cyclonic/anti-cyclonic large-scale forcing is associated with the eddy formation or decay. The source of the vorticity is located at the coast of the Santa Barbara Channel. It is generated by the convergence of the wind system crossing over the San Rafael Mountains and the large-scale northwesterly flow associated with the subtropical high. This vorticity is advected towards the southeast by the northwesterly flow, which contributes to the formation of the streak of positive vorticity. At 6 hours prior to the mature stage, there is an explosive generation of positive vorticity along the coast, coincident with the phase change of the sea breeze circulation (wind turning from onshore to offshore), resulting in the convergence all along the California coast. The generation of vorticity due to convergence along the coast together with the advection of vorticity from the north resulted in the formation of southerly flow along the coast, forming the Catalina Eddy. The importance of diurnal variation and the lack of large-scale forcing are new findings, which are in sharp contrast to prior studies. These differences are due to the inclusion of many short-lived eddy events detected in our study which have not been included in other studies.

  15. Influence of Kuroshio Oceanic Eddies on North Pacific Weather Patterns

    NASA Astrophysics Data System (ADS)

    Ma, X.; Chang, P.; Saravanan, R.; Montuoro, R.; Hsieh, J. S.; Wu, D.; Lin, X.; Wu, L.; Jing, Z.

    2016-02-01

    High-resolution satellite observations reveal energetic meso-scale ocean eddy activity and positive correlation between meso-scale sea surface temperature (SST) and surface wind along oceanic frontal zones, such as the Kuroshio and Gulf Stream, suggesting a potential role of meso-scale oceanic eddies in forcing the atmosphere. Using a 27 km horizontal resolution Weather Research Forecasting (WRF) model forced with observed daily SST at 0.09° spatial resolution during boreal winter season, two ensembles of 10 WRF simulations, in one of which meso-scale SST variability induced by ocean eddies was suppressed, were conducted in the North Pacific to study the local and remote influence of meso-scale oceanic eddies in the Kuroshio Extention Region (KER) on the atmosphere. Suppression of meso-scale oceanic eddies results in a deep tropospheric response along and downstream of the KER, including a significant decrease (increase) in winter season mean rainfall along the KER (west coast of US), a reduction of storm genesis in the KER, and a southward shift of the jet stream and North Pacific storm track in the eastern North Pacific. The simulated local and remote rainfall response to meso-scale oceanic eddies in the KER is also supported by observational analysis. A mechanism invoking moist baroclinic instability is proposed as a plausible explanation for the linkage between meso-scale oceanic eddies in the KER and large-scale atmospheric response in the North Pacific. It is argued that meso-scale oceanic eddies can have a rectified effect on planetary boundary layer moisture, the stability of the lower atmosphere and latent heat release, which in turn affect cyclogenesis. The accumulated effect of the altered storm development downstream further contributes to the equivalent barotropic mean flow change in the eastern North Pacific basin.

  16. Estimates of evapotranspiration in alkaline scrub and meadow communities of Owens Valley, California, using the Bowen-ratio, eddy-correlation, and Penman-combination methods

    USGS Publications Warehouse

    Duell, L. F. W.

    1988-01-01

    In Owens Valley, evapotranspiration (ET) is one of the largest components of outflow in the hydrologic budget and the least understood. ET estimates for December 1983 through October 1985 were made for seven representative locations selected on the basis of geohydrology and the characteristics of phreatophytic alkaline scrub and meadow communities. The Bowen-ratio, eddy-correlation, and Penman-combination methods were used to estimate ET. The results of the analyses appear satisfactory when compared to other estimates of ET. Results by the eddy-correlation method are for a direct and a residual latent-heat flux that is based on sensible-heat flux and energy budget measurements. Penman-combination potential ET estimates were determined to be unusable because they overestimated actual ET. Modification in the psychrometer constant of this method to account for differences between heat-diffusion resistance and vapor-diffusion resistance permitted actual ET to be estimated. The methods may be used for studies in similar semiarid and arid rangeland areas in the Western United States. Meteorological data for three field sites are included in the appendix. Simple linear regression analysis indicates that ET estimates are correlated to air temperature, vapor-density deficit, and net radiation. Estimates of annual ET range from 300 mm at a low-density scrub site to 1,100 mm at a high-density meadow site. The monthly percentage of annual ET was determined to be similar for all sites studied. (Author 's abstract)

  17. Estimates of evapotranspiration in alkaline scrub and meadow communities of Owens Valley, California, using the Bowen-ratio, eddy-correlation, and penman-combination methods

    USGS Publications Warehouse

    Duell, Lowell F. W.

    1990-01-01

    In Owens Valley, evapotranspiration (ET) is one of the largest components of outflow in the hydrologic budget and the least understood. ET estimates for December 1983 through October 1985 were made for seven representative locations selected on the basis of geohydrology and the characteristics of phreatophytic alkaline scrub and meadow communities. The Bowen-ratio, eddy-correlation, and Penman-combination methods were used to estimate ET. The results of the analyses appear satisfactory when compared with other estimates of ET. Results by the eddy-correlation method are for a direct and a residual latent-heat flux that is based on sensible-heat flux and energy-budget measurements. Penman-combination potential-ET estimates were determined to be unusable because they overestimated actual ET. Modification of the psychrometer constant of this method to account for differences between heat-diffusion resistance and vapor-diffusion resistance permitted actual ET to be estimated. The methods described in this report may be used for studies in similar semiarid and arid rangeland areas in the Western United States. Meteorological data for three field sites are included in the appendix of this report. Simple linear regression analysis indicates that ET estimates are correlated to air temperature, vapor-density deficit, and net radiation. Estimates of annual ET range from 301 millimeters at a low-density scrub site to 1,137 millimeters at a high-density meadow site. The monthly percentage of annual ET was determined to be similar for all sites studied.

  18. 3-D residual eddy current field characterisation: applied to diffusion weighted magnetic resonance imaging.

    PubMed

    O'Brien, Kieran; Daducci, Alessandro; Kickler, Nils; Lazeyras, Francois; Gruetter, Rolf; Feiweier, Thorsten; Krueger, Gunnar

    2013-08-01

    Clinical use of the Stejskal-Tanner diffusion weighted images is hampered by the geometric distortions that result from the large residual 3-D eddy current field induced. In this work, we aimed to predict, using linear response theory, the residual 3-D eddy current field required for geometric distortion correction based on phantom eddy current field measurements. The predicted 3-D eddy current field induced by the diffusion-weighting gradients was able to reduce the root mean square error of the residual eddy current field to ~1 Hz. The model's performance was tested on diffusion weighted images of four normal volunteers, following distortion correction, the quality of the Stejskal-Tanner diffusion-weighted images was found to have comparable quality to image registration based corrections (FSL) at low b-values. Unlike registration techniques the correction was not hindered by low SNR at high b-values, and results in improved image quality relative to FSL. Characterization of the 3-D eddy current field with linear response theory enables the prediction of the 3-D eddy current field required to correct eddy current induced geometric distortions for a wide range of clinical and high b-value protocols.

  19. Procedure for Automated Eddy Current Crack Detection in Thin Titanium Plates

    NASA Technical Reports Server (NTRS)

    Wincheski, Russell A.

    2012-01-01

    This procedure provides the detailed instructions for conducting Eddy Current (EC) inspections of thin (5-30 mils) titanium membranes with thickness and material properties typical of the development of Ultra-Lightweight diaphragm Tanks Technology (ULTT). The inspection focuses on the detection of part-through, surface breaking fatigue cracks with depths between approximately 0.002" and 0.007" and aspect ratios (a/c) of 0.2-1.0 using an automated eddy current scanning and image processing technique.

  20. Software compensation of eddy current fields in multislice high order dynamic shimming.

    PubMed

    Sengupta, Saikat; Avison, Malcolm J; Gore, John C; Brian Welch, E

    2011-06-01

    Dynamic B(0) shimming (DS) can produce better field homogeneity than static global shimming by dynamically updating slicewise shim values in a multislice acquisition. The performance of DS however is limited by eddy current fields produced by the switching of 2nd and 3rd order unshielded shims. In this work, we present a novel method of eddy field compensation (EFC) applied to higher order shim induced eddy current fields in multislice DS. This method does not require shim shielding, extra hardware for eddy current compensation or subject specific prescanning. The interactions between shim harmonics are modeled assuming steady state of the medium and long time constant, cross and self term eddy fields in a DS experiment and 'correction factors' characterizing the entire set of shim interactions are derived. The correction factors for a given time between shim switches are shown to be invariable with object scanned, shim switching pattern and actual shim values, allowing for their generalized prospective use. Phantom and human head, 2nd and 3rd order DS experiments performed without any hardware eddy current compensation using the technique show large reductions in field gradients and offsets leading to significant improvements in image quality. This method holds promise as an alternative to expensive hardware based eddy current compensation required in 2nd and 3rd order DS. Copyright © 2011 Elsevier Inc. All rights reserved.

  1. Multi-scale properties of large eddy simulations: correlations between resolved-scale velocity-field increments and subgrid-scale quantities

    NASA Astrophysics Data System (ADS)

    Linkmann, Moritz; Buzzicotti, Michele; Biferale, Luca

    2018-06-01

    We provide analytical and numerical results concerning multi-scale correlations between the resolved velocity field and the subgrid-scale (SGS) stress-tensor in large eddy simulations (LES). Following previous studies for Navier-Stokes equations, we derive the exact hierarchy of LES equations governing the spatio-temporal evolution of velocity structure functions of any order. The aim is to assess the influence of the subgrid model on the inertial range intermittency. We provide a series of predictions, within the multifractal theory, for the scaling of correlation involving the SGS stress and we compare them against numerical results from high-resolution Smagorinsky LES and from a-priori filtered data generated from direct numerical simulations (DNS). We find that LES data generally agree very well with filtered DNS results and with the multifractal prediction for all leading terms in the balance equations. Discrepancies are measured for some of the sub-leading terms involving cross-correlation between resolved velocity increments and the SGS tensor or the SGS energy transfer, suggesting that there must be room to improve the SGS modelisation to further extend the inertial range properties for any fixed LES resolution.

  2. Characterizing the performance of eddy current probes using photoinductive field-mapping

    NASA Astrophysics Data System (ADS)

    Moulder, John C.; Nakagawa, Norio

    1992-12-01

    We present a new method for characterizing the performance of eddy current probes by mapping their electromagnetic fields. The technique is based on the photoinductive effect, the change in the impedance of an eddy current probe induced by laser heating of the material under the probe. The instrument we developed maps a probe's electric field distribution by scanning an infrared laser beam over a thin film of gold lying underneath the probe. Measurements of both photoinductive signals and flaw signals for a series of similar probes demonstrates that the impedance change caused by an electrical-discharge-machined notch or a fatigue crack is proportional to the strength of the photoinductive signal. Thus, photoinductive measurements can supplant the use of artifact standards to calibrate eddy current probes.

  3. Quantifying mesoscale eddies in the Lofoten Basin

    NASA Astrophysics Data System (ADS)

    Raj, R. P.; Johannessen, J. A.; Eldevik, T.; Nilsen, J. E. Ø.; Halo, I.

    2016-07-01

    The Lofoten Basin is the most eddy rich region in the Norwegian Sea. In this paper, the characteristics of these eddies are investigated from a comprehensive database of nearly two decades of satellite altimeter data (1995-2013) together with Argo profiling floats and surface drifter data. An automated method identified 1695/1666 individual anticyclonic/cyclonic eddies in the Lofoten Basin from more than 10,000 altimeter-based eddy observations. The eddies are found to be predominantly generated and residing locally. The spatial distributions of lifetime, occurrence, generation sites, size, intensity, and drift of the eddies are studied in detail. The anticyclonic eddies in the Lofoten Basin are the most long-lived eddies (>60 days), especially in the western part of the basin. We reveal two hotspots of eddy occurrence on either side of the Lofoten Basin. Furthermore, we infer a cyclonic drift of eddies in the western Lofoten Basin. Barotropic energy conversion rates reveals energy transfer from the slope current to the eddies during winter. An automated colocation of surface drifters trapped inside the altimeter-based eddies are used to corroborate the orbital speed of the anticyclonic and cyclonic eddies. Moreover, the vertical structure of the altimeter-based eddies is examined using colocated Argo profiling float profiles. Combination of altimetry, Argo floats, and surface drifter data is therefore considered to be a promising observation-based approach for further studies of the role of eddies in transport of heat and biomass from the slope current to the Lofoten Basin.

  4. Eddy Properties and their Spatiotemporal Variability in the North Indian Ocean from Satellite Altimetry

    NASA Astrophysics Data System (ADS)

    Dandapat, S.; Chakraborty, A.

    2016-12-01

    A comprehensive study on the statistics and variability of mesoscale eddies in the North Indian Ocean (NIO) are investigated using satellite altimetry data for the period of 1993-2014. A hybrid algorithm based on the physical and geometrical properties of mesoscale eddies is applied to detect the eddies and track their propagation. The potential eddies with radius larger than 50 km and lifespan longer than 30 days are considered for the analysis. The NIO consists of two unique tropical basins with the high number of eddy generations and activity: the Arabian Sea (AS) and the Bay of Bengal (BOB). It is noticed that the occurrence of cyclonic eddies (CEs) are found to be significant in AS, while the anticyclonic eddies (ACEs) dominate the BOB. In both the oceans eddies mostly propagate westward. The AS eddies showed the higher mean values, propagation speed, mean radius, mean lifetime than BOB eddies. In the AS, it is found that eddies formed on the western side of the basin persist longer and move towards north where as the number of eddies in the eastern coast of the basin is fewer and short lived. In the BOB, two highly eddy productive zones are identified: offshore of Visakhapatnam and the northern part of western BOB. The occurrence of ACEs dominate the offshore of Visakhapatnam, whereas the CEs in the northern part of western BOB. The ACEs are larger but the CEs have longer lifetime and are more energetic in the BOB. Along with the statistical properties, we also examined the eddy temporal variability in seasonal scale and their structural properties from ARGO data in the NIO. The seasonal variations are found to be significant in AS and BOB and in both the oceans significant correlation has been found between the eddy genesis and local wind stress curl. The strong positive wind stress curl during summer favors the formation of more CEs. In general, both ACEs and CEs in the NIO have single-core vertical structure with the core at a depth of about 100-200 dbar.

  5. A Baroclinic Eddy Mixer: Supercritical Transformation of Compensated Eddies

    NASA Astrophysics Data System (ADS)

    Sutyrin, G.

    2016-02-01

    In contrast to many real-ocean rings and eddies, circular vortices with initial lower layer at rest tend to be highly unstable in idealized two-layer models, unless their radius is made small or the lower layer depth is made artificially large. Numerical simulations of unstable vortices with parameters typical for ocean eddies revealed strong deformations and pulsations of the vortex core in the two-layer setup due to development of corotating tripolar structures in the lower layer during their supercritical transformation. The addition of a middle layer with the uniform potential vorticity weakens vertical coupling between the upper and lower layer that enhances vortex stability and makes the vortex lifespan more realistic. Such a three-layer vortex model possesses smaller lower interface slope than the two-layer model that reduces the potential vorticity gradient in the lower layer and provides with less unstable configurations. While cyclonic eddies become only slightly deformed and look nearly circular when the middle layer with uniform potential vorticity is added, anticyclonic eddies tend to corotating and pulsating elongated states through potential vorticity stripping and stirring. Enhanced vortex stability in such three-layer setup has important implications for adequate representation of the energy transfer across scales.

  6. Eddy-Current Detection Of Cracks In Reinforced Carbon/Carbon

    NASA Technical Reports Server (NTRS)

    Christensen, Scott V.; Koshti, Ajay M.

    1995-01-01

    Investigations of failures of components made of reinforced carbon/carbon show eddy-current flaw-detection techniques applicable to these components. Investigation focused on space shuttle parts, but applicable to other parts made of carbon/carbon materials. Techniques reveal cracks, too small to be detected visually, in carbon/carbon matrix substrates and in silicon carbide coates on substrates. Also reveals delaminations in carbon/carbon matrices. Used to characterize extents and locations of discontinuities in substrates in situations in which ultrasonic techniques and destructive techniques not practical.

  7. Seasonal variability in global eddy diffusion and the effect on neutral density

    NASA Astrophysics Data System (ADS)

    Pilinski, M. D.; Crowley, G.

    2015-04-01

    We describe a method for making single-satellite estimates of the seasonal variability in global-average eddy diffusion coefficients. Eddy diffusion values as a function of time were estimated from residuals of neutral density measurements made by the Challenging Minisatellite Payload (CHAMP) and simulations made using the thermosphere-ionosphere-mesosphere electrodynamics global circulation model (TIME-GCM). The eddy diffusion coefficient results are quantitatively consistent with previous estimates based on satellite drag observations and are qualitatively consistent with other measurement methods such as sodium lidar observations and eddy diffusivity models. Eddy diffusion coefficient values estimated between January 2004 and January 2008 were then used to generate new TIME-GCM results. Based on these results, the root-mean-square sum for the TIME-GCM model is reduced by an average of 5% when compared to density data from a variety of satellites, indicating that the fidelity of global density modeling can be improved by using data from a single satellite like CHAMP. This approach also demonstrates that eddy diffusion could be estimated in near real-time from satellite observations and used to drive a global circulation model like TIME-GCM. Although the use of global values improves modeled neutral densities, there are limitations to this method, which are discussed, including that the latitude dependence of the seasonal neutral-density signal is not completely captured by a global variation of eddy diffusion coefficients. This demonstrates the need for a latitude-dependent specification of eddy diffusion which is also consistent with diffusion observations made by other techniques.

  8. Evaluation of a scalar eddy transport coefficient based on geometric constraints

    NASA Astrophysics Data System (ADS)

    Bachman, S. D.; Marshall, D. P.; Maddison, J. R.; Mak, J.

    2017-01-01

    A suite of idealized models is used to evaluate and compare several previously proposed scalings for the eddy transport coefficient in downgradient mesoscale eddy closures. Of special interest in this comparison is a scaling introduced as part of the eddy parameterization framework of Marshall et al. (2012), which is derived using the inherent geometry of the Eliassen-Palm eddy flux tensor. The primary advantage of using this coefficient in a downgradient closure is that all dimensional terms are explicitly specified and the only uncertainty is a nondimensional parameter, α, which is bounded by one in magnitude. In each model a set of passive tracers is initialized, whose flux statistics are used to invert for the eddy-induced tracer transport. Unlike previous work, where this technique has been employed to diagnose the tensor coefficient of a linear flux-gradient relationship, the idealization of these models allows the lateral eddy transport to be described by a scalar coefficient. The skill of the extant scalings is then measured by comparing their predicted values against the coefficients diagnosed using this method. The Marshall et al. (2012), scaling is shown to scale most closely with the diagnosed coefficients across all simulations. It is shown that the skill of this scaling is due to its functional dependence on the total eddy energy, and that this scaling provides an excellent match to the diagnosed fluxes even in the limit of constant α. Possible extensions to this work, including how to incorporate the resultant transport coefficient into the Gent and McWilliams parameterization, are discussed.

  9. Eddies off Tasmania

    NASA Technical Reports Server (NTRS)

    2002-01-01

    This true-color satellite image shows a large phytoplankton bloom, several hundred square kilometers in size, in the Indian Ocean off the west coast of Tasmania. In this scene, the rich concentration of microscopic marine plants gives the water a lighter, more turquoise appearance which helps to highlight the current patterns there. Notice the eddies, or vortices in the water, that can be seen in several places. It is possible that these eddies were formed by converging ocean currents flowing around Tasmania, or by fresh river runoff from the island, or both. Often, eddies in the sea serve as a means for stirring the water, thus providing nutrients that help support phytoplankton blooms, which in turn provide nutrition for other organisms. Effectively, these eddies help feed the sea (click to read an article on this topic). This image was acquired November 7, 2000, by the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) flying aboard the Orbview-2 satellite. Tasmania is located off Australia's southeastern coast. Image courtesy SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  10. The pines of the Eddy Arboretum

    Treesearch

    John Duffield

    1949-01-01

    The Eddy Arboretum at Placerville, California, contains more than 90 species, varieties, and hybrids of pines, and is therefore of great interest to horticulturists. The Arboretum was established in 1925 as a source of breeding stock for the Eddy Tree Breeding Station, founded in the same year by Mr. James G. Eddy of Seattle. In 1934 Mr. Eddy presented the Arboretum...

  11. On the estimate of the transpiration in Mediterranean heterogeneous ecosystems with the coupled use of eddy covariance and sap flow techniques.

    NASA Astrophysics Data System (ADS)

    Corona, Roberto; Curreli, Matteo; Montaldo, Nicola; Oren, Ram

    2013-04-01

    Mediterranean ecosystems are commonly heterogeneous savanna-like ecosystems, with contrasting plant functional types (PFT) competing for the water use. Mediterranean regions suffer water scarcity due to the dry climate conditions. In semi-arid regions evapotranspiration (ET) is the leading loss term of the root-zone water budget with a yearly magnitude that may be roughly equal to the precipitation. Despite the attention these ecosystems are receiving, a general lack of knowledge persists about the estimate of ET and the relationship between ET and the plant survival strategies for the different PFTs under water stress. During the dry summers these water-limited heterogeneous ecosystems are mainly characterized by a simple dual PFT-landscapes with strong-resistant woody vegetation and bare soil since grass died. In these conditions due to the low signal of the land surface fluxes captured by the sonic anemometer and gas analyzer the widely used eddy covariance may fail and its ET estimate is not robust enough. In these conditions the use of the sap flow technique may have a key role, because theoretically it provides a direct estimate of the woody vegetation transpiration. Through the coupled use of the sap flow sensor observations, a 2D foot print model of the eddy covariance tower and high resolution satellite images for the estimate of the foot print land cover map, the eddy covariance measurements can be correctly interpreted, and ET components (bare soil evaporation and woody vegetation transpiration) can be separated. The case study is at the Orroli site in Sardinia (Italy). The site landscape is a mixture of Mediterranean patchy vegetation types: trees, including wild olives and cork oaks, different shrubs and herbaceous species. An extensive field campaign started in 2004. Land-surface fluxes and CO2 fluxes are estimated by an eddy covariance technique based micrometeorological tower. Soil moisture profiles were also continuously estimated using water

  12. A model relating Eulerian spatial and temporal velocity correlations

    NASA Astrophysics Data System (ADS)

    Cholemari, Murali R.; Arakeri, Jaywant H.

    2006-03-01

    In this paper we propose a model to relate Eulerian spatial and temporal velocity autocorrelations in homogeneous, isotropic and stationary turbulence. We model the decorrelation as the eddies of various scales becoming decorrelated. This enables us to connect the spatial and temporal separations required for a certain decorrelation through the ‘eddy scale’. Given either the spatial or the temporal velocity correlation, we obtain the ‘eddy scale’ and the rate at which the decorrelation proceeds. This leads to a spatial separation from the temporal correlation and a temporal separation from the spatial correlation, at any given value of the correlation relating the two correlations. We test the model using experimental data from a stationary axisymmetric turbulent flow with homogeneity along the axis.

  13. Anatomy of a subtropical intrathermocline eddy

    NASA Astrophysics Data System (ADS)

    Barceló-Llull, Bàrbara; Sangrà, Pablo; Pallàs-Sanz, Enric; Barton, Eric D.; Estrada-Allis, Sheila N.; Martínez-Marrero, Antonio; Aguiar-González, Borja; Grisolía, Diana; Gordo, Carmen; Rodríguez-Santana, Ángel; Marrero-Díaz, Ángeles; Arístegui, Javier

    2017-06-01

    An interdisciplinary survey of a subtropical intrathermocline eddy was conducted within the Canary Eddy Corridor in September 2014. The anatomy of the eddy is investigated using near submesoscale fine resolution two-dimensional data and coarser resolution three-dimensional data. The eddy was four months old, with a vertical extension of 500 m and 46 km radius. It may be viewed as a propagating negative anomaly of potential vorticity (PV), 95% below ambient PV. We observed two cores of low PV, one in the upper layers centered at 85 m, and another broader anomaly located between 175 m and the maximum sampled depth in the three-dimensional dataset (325 m). The upper core was where the maximum absolute values of normalized relative vorticity (or Rossby number), |Ro| =0.6, and azimuthal velocity, U=0.5 m s-1, were reached and was defined as the eddy dynamical core. The typical biconvex isopleth shape for intrathermocline eddies induces a decrease of static stability, which causes the low PV of the upper core. The deeper low PV core was related to the occurrence of a pycnostad layer of subtropical mode water that was embedded within the eddy. The eddy core, of 30 km radius, was in near solid body rotation with period of 4 days. It was encircled by a thin outer ring that was rotating more slowly. The kinetic energy (KE) content exceeded that of available potential energy (APE), KE/APE=1.58; this was associated with a low aspect ratio and a relatively intense rate of spin as indicated by the relatively high value of Ro. Inferred available heat and salt content anomalies were AHA=2.9×1018 J and ASA=14.3×1010 kg, respectively. The eddy AHA and ASA contents per unit volume largely exceed those corresponding to Pacific Ocean intrathermocline eddies. This suggests that intrathermocline eddies may play a significant role in the zonal conduit of heat and salt along the Canary Eddy Corridor.

  14. Eddy Current Testing for Detecting Small Defects in Thin Films

    NASA Astrophysics Data System (ADS)

    Obeid, Simon; Tranjan, Farid M.; Dogaru, Teodor

    2007-03-01

    Presented here is a technique of using Eddy Current based Giant Magneto-Resistance sensor (GMR) to detect surface and sub-layered minute defects in thin films. For surface crack detection, a measurement was performed on a copper metallization of 5-10 microns thick. It was done by scanning the GMR sensor on the surface of the wafer that had two scratches of 0.2 mm, and 2.5 mm in length respectively. In another experiment, metal coatings were deposited over the layers containing five defects with known lengths such that the defects were invisible from the surface. The limit of detection (resolution), in terms of defect size, of the GMR high-resolution Eddy Current probe was studied using this sample. Applications of Eddy Current testing include detecting defects in thin film metallic layers, and quality control of metallization layers on silicon wafers for integrated circuits manufacturing.

  15. Evaluation and Improvement of Eddy Current Position Sensors in Magnetically Suspended Flywheel Systems

    NASA Technical Reports Server (NTRS)

    Dever, Timothy P.; Palazzolo, Alan B.; Thomas, Erwin M., III; Jansen, Ralph H.; McLallin, Kerry (Technical Monitor); Soeder, James (Technical Monitor)

    2001-01-01

    Eddy current position sensor performance is evaluated for use in a high-speed flywheel development system. The flywheel utilizes a five axis active magnetic bearing system. The eddy current sensors are used for position feedback for the bearing controller. Measured characteristics include sensitivity to multiple target materials and susceptibility to noise from the magnetic bearings and from sensor-to-sensor crosstalk. Improvements in axial sensor configuration and techniques for noise reduction are described.

  16. A True Eddy Accumulation - Eddy Covariance hybrid for measurements of turbulent trace gas fluxes

    NASA Astrophysics Data System (ADS)

    Siebicke, Lukas

    2016-04-01

    Eddy covariance (EC) is state-of-the-art in directly and continuously measuring turbulent fluxes of carbon dioxide and water vapor. However, low signal-to-noise ratios, high flow rates and missing or complex gas analyzers limit it's application to few scalars. True eddy accumulation, based on conditional sampling ideas by Desjardins in 1972, requires no fast response analyzers and is therefore potentially applicable to a wider range of scalars. Recently we showed possibly the first successful implementation of True Eddy Accumulation (TEA) measuring net ecosystem exchange of carbon dioxide of a grassland. However, most accumulation systems share the complexity of having to store discrete air samples in physical containers representing entire flux averaging intervals. The current study investigates merging principles of eddy accumulation and eddy covariance, which we here refer to as "true eddy accumulation in transient mode" (TEA-TM). This direct flux method TEA-TM combines true eddy accumulation with continuous sampling. The TEA-TM setup is simpler than discrete accumulation methods while avoiding the need for fast response gas analyzers and high flow rates required for EC. We implemented the proposed TEA-TM method and measured fluxes of carbon dioxide (CO2), methane (CH4) and water vapor (H2O) above a mixed beech forest at the Hainich Fluxnet and ICOS site, Germany, using a G2301 laser spectrometer (Picarro Inc., USA). We further simulated a TEA-TM sampling system using measured high frequency CO2 time series from an open-path gas analyzer. We operated TEA-TM side-by-side with open-, enclosed- and closed-path EC flux systems for CO2, H2O and CH4 (LI-7500, LI-7200, LI-6262, LI-7700, Licor, USA, and FGGA LGR, USA). First results show that TEA-TM CO2 fluxes were similar to EC fluxes. Remaining differences were similar to those between the three eddy covariance setups (open-, enclosed- and closed-path gas analyzers). Measured TEA-TM CO2 fluxes from our physical

  17. Seasonal Variability in Global Eddy Diffusion and the Effect on Thermospheric Neutral Density

    NASA Astrophysics Data System (ADS)

    Pilinski, M.; Crowley, G.

    2014-12-01

    We describe a method for making single-satellite estimates of the seasonal variability in global-average eddy diffusion coefficients. Eddy diffusion values as a function of time between January 2004 and January 2008 were estimated from residuals of neutral density measurements made by the CHallenging Minisatellite Payload (CHAMP) and simulations made using the Thermosphere Ionosphere Mesosphere Electrodynamics - Global Circulation Model (TIME-GCM). The eddy diffusion coefficient results are quantitatively consistent with previous estimates based on satellite drag observations and are qualitatively consistent with other measurement methods such as sodium lidar observations and eddy-diffusivity models. The eddy diffusion coefficient values estimated between January 2004 and January 2008 were then used to generate new TIME-GCM results. Based on these results, the RMS difference between the TIME-GCM model and density data from a variety of satellites is reduced by an average of 5%. This result, indicates that global thermospheric density modeling can be improved by using data from a single satellite like CHAMP. This approach also demonstrates how eddy diffusion could be estimated in near real-time from satellite observations and used to drive a global circulation model like TIME-GCM. Although the use of global values improves modeled neutral densities, there are some limitations of this method, which are discussed, including that the latitude-dependence of the seasonal neutral-density signal is not completely captured by a global variation of eddy diffusion coefficients. This demonstrates the need for a latitude-dependent specification of eddy diffusion consistent with diffusion observations made by other techniques.

  18. Eddy Fluxes and Sensitivity of the Water Cycle to Spatial Resolution in Idealized Regional Aquaplanet Model Simulations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hagos, Samson M.; Leung, Lai-Yung R.; Gustafson, William I.

    2014-02-28

    A multi-scale moisture budget analysis is used to identify the mechanisms responsible for the sensitivity of the water cycle to spatial resolution using idealized regional aquaplanet simulations. In the higher resolution simulations, moisture transport by eddies fluxes dry the boundary layer enhancing evaporation and precipitation. This effect of eddies, which is underestimated by the physics parameterizations in the low-resolution simulations, is found to be responsible for the sensitivity of the water cycle both directly, and through its upscale effect, on the mean circulation. Correlations among moisture transport by eddies at adjacent ranges of scales provides the potential for reducing thismore » sensitivity by representing the unresolved eddies by their marginally resolved counterparts.« less

  19. Interaction Between Eddies and Mean Flow in Jupiter's Atmosphere: Analysis of Cassini Imaging Data

    NASA Technical Reports Server (NTRS)

    Salyk, Colette; Ingersoll, Andrew P.; Lorre, Jean; Vasavada, Ashwin; DelGenio, Anthony D.

    2006-01-01

    Beebe et al. [Beebe, R.F., et al., 1980. Geophys. Res. Lett. 17, 1-4] and Ingersoll et al. [Ingersoll, A.P., et al., 1981. J. Geophys. Res. 86, 8733-8743] used images from Voyagers 1 and 2 to analyze the interaction between zonal winds and eddies in Jupiter's atmosphere. They reported a high positive correlation between Jupiter's eddy momentum flux, pu'v', and the variation of zonal velocity with latitude, du/dy. This correlation implied a surprisingly high rate of conversion of energy from eddies to zonal flow: approx. 1.5-3.0 W/sq m, a value more than 10% of Jupiter s thermal flux emission. However, Sromovsky et al. [Sromovsky, L.A., et al., 1982. J. Atmos. Sci. 39,1413-1432] argued that possible biases in the analysis could have caused an artificially high correlation. In addition, significant differences in the derived eddy flux between datasets put into question the robustness of any one result. We return to this long-standing puzzle using images of Jupiter from the Cassini flyby of December 2000. Our method is similar to previous analyses, but utilizes an automatic feature tracker instead of the human eye. The number of velocity vectors used in this analysis is over 200,000, compared to the 14,000 vectors used by Ingersoll et al. We also find a positive correlation between u'v' and du/dy and derive a global average power per unit mass, u'v' du/dy, ranging from (7.1-12.3) x 10(exp -5)W/kg. Utilizing Ingersoll et al.'s estimate of the mass per unit area involved in the transport, this would imply a rate of energy conversion of approx.0.7-1.2 W/sq m. We discuss the implications of this result and employ several tests to demonstrate its robustness.

  20. True eddy accumulation and eddy covariance methods and instruments intercomparison for fluxes of CO2, CH4 and H2O above the Hainich Forest

    NASA Astrophysics Data System (ADS)

    Siebicke, Lukas

    2017-04-01

    -path laser spectrometers). We present results of CO2 and H2O fluxes from the following six instruments, i.e. combinations of sonic anemometers/gas analyzers (and methods): METEK-uSonic3/Picarro-G2301 (TEA), METEK-uSonic3/LI-7500 (EC), Gill-R3/LI-6262 (EC), Gill-R3/LI-7200 (EC), Gill-HS/LI-7200 (EC), Gill-R3/LGR-FGGA (EC). Further, we present results of much more difficult to measure CH4 fluxes from the following three instruments, i.e. combinations of sonic anemometers/gas analyzers (and methods): METEK-uSonic3/Picarro-G2301 (TEA), Gill-R3/LI-7700 (EC), Gill-R3/LGR-FGGA (EC). We observed that CO2, CH4 and H2O fluxes from the side-by-side measurements by true eddy accumulation and eddy covariance methods correlated well. Secondly, the difference between the TEA and EC methods using the same sonic anemometer but different gas analyzer was often smaller than the mismatch of the various side-by-side eddy covariance measurements using different sonic anemometers and gas analyzers. Signal-to-noise ratios of CH4 fluxes from the true eddy accumulation system system were superior to both eddy covariance sensors (open-path LI-7700 and closed-path CRDS LGR-FGGA sensors). We conclude that our novel implementation of the true eddy accumulation method demonstrated high signal-to-noise ratios, applicability to slow-response gas analyzers, small power consumption and direct proxy-free ecosystem-scale trace gas flux measurements of CO2, CH4 and H2O. The current results suggest that true eddy accumulation would be suitable and should be applied as the method-of-choice for direct flux measurements of a large number of atmospheric constituents beyond CO2 and H2O, including isotopes, aerosols, volatile organic compounds and other trace gases for which eddy covariance might not be a viable alternative. We will further develop true eddy accumulation as a novel approach using multiplexed systems for spatially distributed flux measurements.

  1. Obituary: John Allen Eddy (1931-2009)

    NASA Astrophysics Data System (ADS)

    Gingerich, Owen

    2011-12-01

    , "This Mercury is Hot! Red Shift, Black Body, and a Perfect Radiator." Ironically, within a few years he was laid off from his HAO position as a result of budget cuts at its parent organization, the National Center for Atmospheric Research (NCAR). In an interview a quarter of a century later Eddy remarked, "I found out how hard it is for a person with a Ph.D. to get another job at that time, and often wished I didn't have one, for I was often told, true or not, that I was overqualified for the few jobs that turned up." Eddy found a temporary job writing a book for NASA as part of a series on the Skylab spacecraft; the book, The New Sun, was published in 1979. Again, working on his own time, he revived an earlier finding, namely, that between 1645 and 1715 the sun was almost devoid of spots, and he greatly extended the previous work of Gustav Spörer and Walter Maunder by showing during that period a dearth of aurorae and atmospheric carbon-14, a diminution of the solar corona during eclipses, and probably a correlation with cooling of the earth. For onomatopoiec reasons, the rhythm of the m's, Eddy chose the title "the Maunder Minimum" for the phenomenon, and for his unusually long cover story in the 18 June 1976 issue of Science. The paper was well received, and for a while Eddy was an invited speaker fifty times a year. In 1977, Eddy scored yet again, with his third cover story in Science, a jointly authored paper on solar rotation in the early 17th century. In 1977-78 Eddy had a fellowship at the Harvard-Smithsonian Center for Astrophysics in Cambridge, and during that time Ken Brecher and I had a series of conversations with Jack in which we worked out a proposal for a historical astronomy division within the AAS; since I had just been an AAS Councilor, I negotiated with the Society for its actualization, and Eddy became the first HAD president, in 1981-83. He introduced the logo, Dürer's ancient astronomer, and at the end of his term, the plaque with the motto "Ich

  2. Nonlinear, non-stationary image processing technique for eddy current NDE

    NASA Astrophysics Data System (ADS)

    Yang, Guang; Dib, Gerges; Kim, Jaejoon; Zhang, Lu; Xin, Junjun; Udpa, Lalita

    2012-05-01

    Automatic analysis of eddy current (EC) data has facilitated the analysis of large volumes of data generated in the inspection of steam generator tubes in nuclear power plants. The traditional procedure for analysis of EC data includes data calibration, pre-processing, region of interest (ROI) detection, feature extraction and classification. Accurate ROI detection has been enhanced by pre-processing, which involves reducing noise and other undesirable components as well as enhancing defect indications in the raw measurement. This paper presents the Hilbert-Huang Transform (HHT) for feature extraction and support vector machine (SVM) for classification. The performance is shown to significantly better than the existing rule based classification approach used in industry.

  3. Eddy current system for inspection of train hollow axles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chady, Tomasz; Psuj, Grzegorz; Sikora, Ryszard

    2014-02-18

    The structural integrity of wheelsets used in rolling stock is of great importance to the safety. In this paper, electromagnetic system with an eddy current transducer suitable for the inspection of hollow axles have been presented. The transducer was developed to detect surface braking defects having depth not smaller than 0.5 mm. Ultrasound technique can be utilized to inspect the whole axle, but it is not sufficiently sensitive to shallow defects located close to the surface. Therefore, the electromagnetic technique is proposed to detect surface breaking cracks that cannot be detected by ultrasonic technique.

  4. A New Approach to Extract Forest Water Use Efficiency from Eddy Covariance Data

    NASA Astrophysics Data System (ADS)

    Scanlon, T. M.; Sulman, B. N.

    2016-12-01

    Determination of forest water use efficiency (WUE) from eddy covariance data typically involves the following steps: (a) estimating gross primary productivity (GPP) from direct measurements of net ecosystem exchange (NEE) by extrapolating nighttime ecosystem respiration (ER) to daytime conditions, and (b) assuming direct evaporation (E) is minimal several days after rainfall, meaning that direct measurements of evapotranspiration (ET) are identical to transpiration (T). Both of these steps could lead to errors in the estimation of forest WUE. Here, we present a theoretical approach for estimating WUE through the analysis of standard eddy covariance data, which circumvents these steps. Only five statistics are needed from the high-frequency time series to extract WUE: CO2 flux, water vapor flux, standard deviation in CO2 concentration, standard deviation in water vapor concentration, and the correlation coefficient between CO2 and water vapor concentration for each half-hour period. The approach is based on the assumption that stomatal fluxes (i.e. photosynthesis and transpiration) lead to perfectly negative correlations and non-stomatal fluxes (i.e. ecosystem respiration and direct evaporation) lead to perfectly positive correlations within the CO2 and water vapor high frequency time series measured above forest canopies. A mathematical framework is presented, followed by a proof of concept using eddy covariance data and leaf-level measurements of WUE.

  5. Correction of eddy current distortions in high angular resolution diffusion imaging.

    PubMed

    Zhuang, Jiancheng; Lu, Zhong-Lin; Vidal, Christine Bouteiller; Damasio, Hanna

    2013-06-01

    To correct distortions caused by eddy currents induced by large diffusion gradients during high angular resolution diffusion imaging without any auxiliary reference scans. Image distortion parameters were obtained by image coregistration, performed only between diffusion-weighted images with close diffusion gradient orientations. A linear model that describes distortion parameters (translation, scale, and shear) as a function of diffusion gradient directions was numerically computed to allow individualized distortion correction for every diffusion-weighted image. The assumptions of the algorithm were successfully verified in a series of experiments on phantom and human scans. Application of the proposed algorithm in high angular resolution diffusion images markedly reduced eddy current distortions when compared to results obtained with previously published methods. The method can correct eddy current artifacts in the high angular resolution diffusion images, and it avoids the problematic procedure of cross-correlating images with significantly different contrasts resulting from very different gradient orientations or strengths. Copyright © 2012 Wiley Periodicals, Inc.

  6. Static Vented Chamber and Eddy Covariance Methane Flux Comparisons in Mid-South US Rice

    NASA Astrophysics Data System (ADS)

    Reba, M. L.; Fong, B.; Adviento-Borbe, A.; Runkle, B.; Suvocarev, K.; Rival, I.

    2017-12-01

    Rice cultivation contributes higher amounts of GHG emissions (CO2 and CH4) due to flooded field conditions. A comparison between eddy covariance and static vented flux chamber measurement techniques is presented. Rice GHG emissions originating from plot level chambers may not accurately describe the aggregate effects of all the soil and micrometeorological variations across a production field. Eddy covariance (EC) is a direct, integrated field measurement of field scale trace gases. Flux measurements were collected in NE Arkansas production size rice fields (16 ha, 40 ac) during the 2015 and 2016 production seasons (June-August) in continuous flood (CF) irrigation. The study objectives included quantifying the difference between chamber and EC measurements, and categorizing flux behavior to growth stage and field history. EC daily average emissions correlated with chamber measurements (R2=0.27-0.54) more than average from 09:00-12:00 which encompassed chamber measurement times (R2=0.23-0.32). Maximum methane emissions occurred in the late afternoon from 14:00-18:00 which corresponded with maximum soil heat flux and air temperature. The total emissions from the study fields ranged from 27-117 kg CH4-C ha-1 season-1. The emission profile was lower in 2015, most likely due to higher rainfall and cooler temperatures during the growing season compared to 2016. These findings improve our understanding of GHG emissions at the field scale under typical production practices and validity of chamber and EC flux measurement techniques.

  7. Colorstratigraphy; A New Stratigraphic Correlation Technique

    NASA Astrophysics Data System (ADS)

    Nanayakkara, N. U.; Ranasinghage, P. N.; Priyantha, C.; Abillapitiya, T.

    2016-12-01

    Here we introduce a novel stratigraphic technique namely colorstratigraphy for correlating sedimentary sequences. Minihagalkanda is about 1 km long amphitheater like sedimentary terrain, situated at the southeastern coast of Sri Lanka. It has Miocene sedimentary sequences, separated in to 10-12 m high small hillocks by erosion, and bounded by about 30 m high escarpment. Sandstone, yellowish sandy clay, greenish silty clay sequences are capped by 4-5 m limestone bed in these hillocks but not at the boundary escarpment. Stratigraphic profiles at two hillocks and the boundary escarpment, separated each other by 200-300 m, were selected to test the new colorstartigraphic correlation technique. Color reflectance (DSR) was measured at four samples in each sequence at every profile and hence altogether 36 reflectance measurements were taken using Minolta 2500D hand-held color spectrophotometer. The first-derivative of the reflectance spectra (dR/dλ) defines the "spectral shape" of the sample. Therefore, DSR data (360-740 nm) measured at 10 nm resolution were used to calculate a center-weighted, first-derivative spectra for each reflectance sample consisting of 39 channels. Particle size of each sequence was measured at all 03 profiles using laser particle size analyzer to verify the stratigraphic correlation. Mean reflectance spectrum for each sequence at all 03 profiles were plotted on the same graph for comparison. Same was done for the grain size spectrums. Discriminant function analysis was performed separately for dsr data and grain size data using a number assigned to each sedimentary sequence as the grouping variable Color spectrums of sandstone, yellowish sandy clay, and greenish silty clay sequences at all three profiles perfectly match showing clear stratigraphic correlation among these three stratigraphic profiles. Matching grain size distribution curves of the three sequence at the three profiles verify the stratigraphic correlation. Perfect 100

  8. Mesoscale eddies and T richodesmium spp. distributions in the southwestern North Atlantic

    PubMed Central

    McGillicuddy, Dennis J.; Flierl, Glenn R.; Davis, Cabell S.; Dyhrman, Sonya T.; Waterbury, John B.

    2015-01-01

    Abstract Correlations of Trichodesmium colony abundance with the eddy field emerged in two segments of Video Plankton Recorder observations made in the southwestern North Atlantic during fall 2010 and spring 2011. In fall 2010, local maxima in abundance were observed in cyclones. We hypothesized surface Ekman transport convergence as a mechanism for trapping buoyant colonies in cyclones. Idealized models supported the potential of this process to influence the distribution of buoyant colonies over time scales of several months. In spring 2011, the highest vertically integrated colony abundances were observed in anticyclones. These peaks in abundance correlated with anomalously fresh water, suggesting riverine input as a driver of the relationship. These contrasting results in cyclones and anticyclones highlight distinct mechanisms by which mesoscale eddies can influence the abundance and distribution of Trichodesmium populations of the southwestern North Atlantic. PMID:26937328

  9. Applying a simple three-dimensional eddy correlation system for latent and sensible heat flux to contrasting forest canopies

    NASA Astrophysics Data System (ADS)

    Bernhofer, Ch.

    1992-06-01

    A simple eddy correlation system is presented that allows on-line calculation of latent and sensible heat fluxes. The system is composed of a three dimensional propeller anemometer, a thermocouple and a capacitance relative humidity sensor. Results from two contrasting sites demonstrate the capability of the system to measure turbulent fluxes under varying conditions. A dry mixed (dominantly coniferous) forest in hilly terrain in Austria is compared to a well irrigated, heavily transpiring, deciduous pecan orchard in the Southwest of the US. The US site shows insufficient closure of the energy balance that is attributed to non-turbulent fluxes under advective conditions in a stable boundary layer (Blanford et al., 1991) while the Austrian site exhibits almost perfect closure with the use of the very same instruments when the boundary layer is convective and advection is negligible.

  10. Eddy properties in the Southern California Current System

    NASA Astrophysics Data System (ADS)

    Chenillat, Fanny; Franks, Peter J. S.; Capet, Xavier; Rivière, Pascal; Grima, Nicolas; Blanke, Bruno; Combes, Vincent

    2018-05-01

    The California Current System (CCS) is an eastern boundary upwelling system characterized by strong eddies that are often generated at the coast. These eddies contribute to intense, long-distance cross-shelf transport of upwelled water with enhanced biological activity. However, the mechanisms of formation of such coastal eddies, and more importantly their capacity to trap and transport tracers, are poorly understood. Their unpredictability and strong dynamics leave us with an incomplete picture of the physical and biological processes at work, their effects on coastal export, lateral water exchange among eddies and their surrounding waters, and how long and how far these eddies remain coherent structures. Focusing our analysis on the southern part of the CCS, we find a predominance of cyclonic eddies, with a 25-km radius and a SSH amplitude of 6 cm. They are formed near shore and travel slightly northwest offshore for 190 days at 2 km day-1. We then study one particular, representative cyclonic eddy using a combined Lagrangian and Eulerian numerical approach to characterize its kinematics. Formed near shore, this eddy trapped a core made up of 67% California Current waters and 33% California Undercurrent waters. This core was surrounded by other waters while the eddy detached from the coast, leaving the oldest waters at the eddy's core and the younger waters toward the edge. The eddy traveled several months as a coherent structure, with only limited lateral exchange within the eddy.

  11. Turbulent Eddies in a Compressible Jet in Crossflow Measured using Pulse-Burst PIV

    NASA Astrophysics Data System (ADS)

    Beresh, Steven; Wagner, Justin; Henfling, John; Spillers, Russell; Pruett, Brian

    2015-11-01

    Pulse-burst Particle Image Velocimetry (PIV) has been employed to acquire time-resolved data at 25 kHz of a supersonic jet exhausting into a subsonic compressible crossflow. Data were acquired along the windward boundary of the jet shear layer and used to identify turbulent eddies as they convect downstream in the far-field of the interaction. Eddies were found to have a tendency to occur in closely-spaced counter-rotating pairs and are routinely observed in the PIV movies, but the variable orientation of these pairs makes them difficult to detect statistically. Correlated counter-rotating vortices are more strongly observed to pass by at a larger spacing, both leading and trailing the reference eddy. This indicates the paired nature of the turbulent eddies and the tendency for these pairs to convect through the field of view at repeatable spacings. Velocity spectra reveal a peak at a frequency consistent with this larger spacing between shear-layer vortices rotating with identical sign. Super-sampled velocity spectra to 150 kHz reveal a power-law dependency of -5/3 in the inertial subrange as well as a -1 dependency at lower frequencies attributed to the scales of the dominant shear-layer eddies.

  12. Improved Imaging With Laser-Induced Eddy Currents

    NASA Technical Reports Server (NTRS)

    Chern, Engmin J.

    1993-01-01

    System tests specimen of material nondestructively by laser-induced eddy-current imaging improved by changing method of processing of eddy-current signal. Changes in impedance of eddy-current coil measured in absolute instead of relative units.

  13. Moffatt eddies at an interface

    NASA Astrophysics Data System (ADS)

    Shtern, Vladimir

    2014-12-01

    It is shown that an infinite set of eddies can develop near the interface-wall intersection in a two-fluid flow. A striking feature is that the eddy occurrence depends on from what side of the interface the flow is driven. In air-water flows where the viscosity ratio is 0.018, the eddies develop if a driving source is located on (i) the air side for , (ii) any side for , and (iii) the water side for , where is the upper interface-wall angle.

  14. High-speed technique based on a parallel projection correlation procedure for digital image correlation

    NASA Astrophysics Data System (ADS)

    Zaripov, D. I.; Renfu, Li

    2018-05-01

    The implementation of high-efficiency digital image correlation methods based on a zero-normalized cross-correlation (ZNCC) procedure for high-speed, time-resolved measurements using a high-resolution digital camera is associated with big data processing and is often time consuming. In order to speed-up ZNCC computation, a high-speed technique based on a parallel projection correlation procedure is proposed. The proposed technique involves the use of interrogation window projections instead of its two-dimensional field of luminous intensity. This simplification allows acceleration of ZNCC computation up to 28.8 times compared to ZNCC calculated directly, depending on the size of interrogation window and region of interest. The results of three synthetic test cases, such as a one-dimensional uniform flow, a linear shear flow and a turbulent boundary-layer flow, are discussed in terms of accuracy. In the latter case, the proposed technique is implemented together with an iterative window-deformation technique. On the basis of the results of the present work, the proposed technique is recommended to be used for initial velocity field calculation, with further correction using more accurate techniques.

  15. Eddy Covariance Measurements of the Sea-Spray Aerosol Flu

    NASA Astrophysics Data System (ADS)

    Brooks, I. M.; Norris, S. J.; Yelland, M. J.; Pascal, R. W.; Prytherch, J.

    2015-12-01

    Historically, almost all estimates of the sea-spray aerosol source flux have been inferred through various indirect methods. Direct estimates via eddy covariance have been attempted by only a handful of studies, most of which measured only the total number flux, or achieved rather coarse size segregation. Applying eddy covariance to the measurement of sea-spray fluxes is challenging: most instrumentation must be located in a laboratory space requiring long sample lines to an inlet collocated with a sonic anemometer; however, larger particles are easily lost to the walls of the sample line. Marine particle concentrations are generally low, requiring a high sample volume to achieve adequate statistics. The highly hygroscopic nature of sea salt means particles change size rapidly with fluctuations in relative humidity; this introduces an apparent bias in flux measurements if particles are sized at ambient humidity. The Compact Lightweight Aerosol Spectrometer Probe (CLASP) was developed specifically to make high rate measurements of aerosol size distributions for use in eddy covariance measurements, and the instrument and data processing and analysis techniques have been refined over the course of several projects. Here we will review some of the issues and limitations related to making eddy covariance measurements of the sea spray source flux over the open ocean, summarise some key results from the last decade, and present new results from a 3-year long ship-based measurement campaign as part of the WAGES project. Finally we will consider requirements for future progress.

  16. Mesoscale Eddies, Satellite Altimetry, and New Production in the Sargasso Sea

    NASA Technical Reports Server (NTRS)

    Siegel, David A.; McGillicuddy, Dennis J., Jr.; Fields, Erik A.

    1999-01-01

    Satellite altimetry and hydrographic observations are used to characterize the mesoscale eddy field in the Sargasso Sea near Bermuda and to address the role of physical processes on the supply of new nutrients to the euphotic zone. The observed sea level anomaly (SLA) field is dominated by the occurrence of westward propagating features with SLA signatures as large as 25 cm, Eulerian temporal scales of roughly a month, lifetimes of several months, spatial scales of approximately 200 km, and a propagation of approximately 5 cm/s. Hydrographic estimates of dynamic height anomaly (referenced to 4000 dbar) are well correlated with satellite SLA (r(exp 2) = 0.65), and at least 85% of the observed dynamic height variability is associated with the first baroclinic mode of motion. This allows us to apply the satellite observations to remotely sensed estimate isopycnal displacements and the flux of nutrients into the euphotic zone due to eddy pumping. Eddy pumping is the process by which mesoscale eddies induce isopycnal displacements that lift nutrient-replete waters into the euphotic zone, driving new primary production. A kinematic approach to the estimation of the eddy pumping results in a flux of 0.24 +/- 0.1 mol N/sq m (including a scale estimate for the small contribution due to 18 deg water eddies). This flux is more than an order of magnitude larger than the diapycnal diffusive flux as well as scale estimates for the vertical transport due to isopycnal mixing along sloping isopycnal surfaces. Eddy pumping and wintertime convection are the two dominant mechanisms transporting new nutrients into the euphotic zone, and the sum of all physical new nutrient supply fluxes effectively balances previous geochemical estimates of annual new production for this site. However, if biological transports (e.g., nitrogen fixation, etc.) are significant, the new nitrogen supply budget will be in excess of geochemical new production estimates. This suggests that the various physical

  17. Mesoscale Eddies, Satellite Altimetry, and New Production in the Sargasso Sea

    NASA Technical Reports Server (NTRS)

    Siegel, David A.; McGillicuddy, Dennis J., Jr.; Fields, Erik A.

    1999-01-01

    Satellite altimetry and hydrographic observations are used to characterize the mesoscale eddy field in the Sargasso Sea near Bermuda and to address the role of physical processes on the supply of new nutrients to the euphotic zone. The observed sea level anomaly (SLA) field is dominated by the occurrence of westward propagating features with SLA signatures as large as 25 cm, Eulerian temporal scales of roughly a month, lifetimes of several months, spatial scales of approximately 200 km, and a propagation of approximately 5 cm/s . Hydrographic estimates of dynamic height anomaly (referenced to 4000 dbar) are well correlated with satellite SLA (r(sup 2) = 0.65), and at least 85% of the observed dynamic height variability is associated with the first baroclinic mode of motion. This allows us to apply the satellite observations to remotely estimate isopycnal displacements and the flux of nutrients into the euphotic zone due to eddy pumping. Eddy pumping is the process by which mesoscale eddies induce isopycnal displacements that lift nutrient- replete waters into the euphotic zone, driving new primary production. A kinematic approach to the estimation of the eddy pumping results in a flux of 0.24+/-0.1 mol N/sq m/yr (including a scale estimate for the small contribution due to 18 deg water eddies). This flux is more than an order of magnitude larger than the diapycnal diffusive flux as well as scale estimates for the vertical transport due to isopycnal mixing along sloping isopycnal surfaces. Eddy pumping and wintertime convection are the two dominant mechanisms transporting new nutrients into the euphotic zone, and the sum of all physical new nutrient supply fluxes effectively balances previous geochemical estimates of annual new production for this site. However, if biological transports (e.g., nitrogen fixation, etc.) are significant, the new nitrogen supply budget will be in excess of geochemical new production estimates. This suggests that the various physical and

  18. Eddy Current for Sizing Cracks in Canisters for Dry Storage of Used Nuclear Fuel

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Meyer, Ryan M.; Jones, Anthony M.; Pardini, Allan F.

    2014-01-01

    The storage of used nuclear fuel (UNF) in dry canister storage systems (DCSSs) at Independent Spent Fuel Storage Installations (ISFSI) sites is a temporary measure to accommodate UNF inventory until it can be reprocessed or transferred to a repository for permanent disposal. Policy uncertainty surrounding the long-term management of UNF indicates that DCSSs will need to store UNF for much longer periods than originally envisioned. Meanwhile, the structural and leak-tight integrity of DCSSs must not be compromised. The eddy current technique is presented as a potential tool for inspecting the outer surfaces of DCSS canisters for degradation, particularly atmospheric stressmore » corrosion cracking (SCC). Results are presented that demonstrate that eddy current can detect flaws that cannot be detected reliably using standard visual techniques. In addition, simulations are performed to explore the best parameters of a pancake coil probe for sizing of SCC flaws in DCSS canisters and to identify features in frequency sweep curves that may potentially be useful for facilitating accurate depth sizing of atmospheric SCC flaws from eddy current measurements.« less

  19. Detection of subsurface-intensified eddies from observations of the sea-surface: a case study for Mediterranean Water Eddies in a long-term high-resolution simulation

    NASA Astrophysics Data System (ADS)

    Ciani, Daniele; Carton, Xavier; Barbosa Aguiar, Ana Claudia; Peliz, Alvaro; Bashmachnikov, Igor; Ienna, Federico; Chapron, Bertrand

    2017-04-01

    Meddy potential vorticity structure at depth (around 1000 m below the sea-surface). Such anomalies were long-lived, mostly migrated exhibiting southwestward trajectories, their intensities were O(10 cm) and extended horizontally up to more than 300 km (around 1.5 times the Meddy diameter). On the other hand, the Meddies thermohaline surface signatures proved to be mostly dominated by the local surface conditions and their structure poorly correlated to the Meddy structure at depth (e.g. the Meddy volume-integrated salt and temperature content). These results point out that satellite altimetry is the most suitable approach to track subsurface-intensified eddies from observations of the sea-surface, also encouraging the use of future high-resolution altimetric observations (e.g. SWOT) to detect subsurface oceanic motions from satellite sensors.

  20. Mechanical properties and eddy current testing of thermally aged Z3CN20.09M cast duplex stainless steel

    NASA Astrophysics Data System (ADS)

    Liu, Tonghua; Wang, Wei; Qiang, Wenjiang; Shu, Guogang

    2018-04-01

    To study the thermal aging embrittlement of Z3CN20.09M duplex stainless steel produced in China, accelerated thermal aging experiments were carried out at 380 °C up to 9000 h. Microhardness measurements, Charpy impact and eddy current tests were performed on aged samples to characterize their thermal aging embrittlement. The results showed that the signal amplitude of eddy current decreased with the increase in aging time. Two quantitative correlations of the eddy current signal amplitude with both the Charpy impact energy, and the Vickers microhardness of the ferrite phase are obtained. The study showed that eddy current testing could be used to non-destructively evaluate the thermal aging embrittlement of cast duplex stainless steels.

  1. Impact of water use efficiency on eddy covariance flux partitioning using correlation structure analysis

    NASA Astrophysics Data System (ADS)

    Anderson, Ray; Skaggs, Todd; Alfieri, Joseph; Kustas, William; Wang, Dong; Ayars, James

    2016-04-01

    Partitioned land surfaces fluxes (e.g. evaporation, transpiration, photosynthesis, and ecosystem respiration) are needed as input, calibration, and validation data for numerous hydrological and land surface models. However, one of the most commonly used techniques for measuring land surface fluxes, Eddy Covariance (EC), can directly measure net, combined water and carbon fluxes (evapotranspiration and net ecosystem exchange/productivity). Analysis of the correlation structure of high frequency EC time series (hereafter flux partitioning or FP) has been proposed to directly partition net EC fluxes into their constituent components using leaf-level water use efficiency (WUE) data to separate stomatal and non-stomatal transport processes. FP has significant logistical and spatial representativeness advantages over other partitioning approaches (e.g. isotopic fluxes, sap flow, microlysimeters), but the performance of the FP algorithm is reliant on the accuracy of the intercellular CO2 (ci) concentration used to parameterize WUE for each flux averaging interval. In this study, we tested several parameterizations for ci as a function of atmospheric CO2 (ca), including (1) a constant ci/ca ratio for C3 and C4 photosynthetic pathway plants, (2) species-specific ci/ca-Vapor Pressure Deficit (VPD) relationships (quadratic and linear), and (3) generalized C3 and C4 photosynthetic pathway ci/ca-VPD relationships. We tested these ci parameterizations at three agricultural EC towers from 2011-present in C4 and C3 crops (sugarcane - Saccharum officinarum L. and peach - Prunus persica), and validated again sap-flow sensors installed at the peach site. The peach results show that the species-specific parameterizations driven FP algorithm came to convergence significantly more frequently (~20% more frequently) than the constant ci/ca ratio or generic C3-VPD relationship. The FP algorithm parameterizations with a generic VPD relationship also had slightly higher transpiration (5 Wm-2

  2. Eddy Current Testing, RQA/M1-5330.17.

    ERIC Educational Resources Information Center

    National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.

    As one in the series of classroom training handbooks, prepared by the U.S. space program, instructional material is presented in this volume concerning familiarization and orientation on eddy current testing. The subject is presented under the following headings: Introduction, Eddy Current Principles, Eddy Current Equipment, Eddy Current Methods,…

  3. A comparison of the structure, properties, and water mass composition of quasi-isotropic eddies in western boundary currents in an eddy-resolving ocean model

    NASA Astrophysics Data System (ADS)

    Rykova, Tatiana; Oke, Peter R.; Griffin, David A.

    2017-06-01

    Using output from a near-global eddy-resolving ocean model, we analyse the properties and characteristics of quasi-isotropic eddies in five Western Boundary Current (WBC) regions, including the extensions of the Agulhas, East Australian Current (EAC), Brazil-Malvinas Confluence (BMC), Kuroshio and Gulf Stream regions. We assess the model eddies by comparing to satellite and in situ observations, and show that most aspects of the model's representation of eddies are realistic. We find that the mean eddies differ dramatically between these WBC regions - all with some unique and noteworthy characteristics. We find that the vertical displacement of isopycnals of Agulhas eddies is the greatest, averaging 350-450 m at depths of over 800-900 m. EAC (BMC) eddies are the least (most) barotropic, with only 50% (85-90%) of the velocity associated with the barotropic mode. Kuroshio eddies are the most stratified, resulting in small isopycnal displacement, even for strong eddies; and Gulf Stream eddies carry the most heat. Despite their differences, we explicitly show that the source waters for anticyclonic eddies are a mix of the WBC water (from the boundary current itself) and water that originates equatorward of the WBC eddy-field; and cyclonic eddies are a mix of WBC water and water that originates poleward of the WBC eddy-field.

  4. Eddy current damper

    NASA Technical Reports Server (NTRS)

    Ellis, R. C.; Fink, R. A.; Rich, R. W.

    1989-01-01

    A high torque capacity eddy current damper used as a rate limiting device for a large solar array deployment mechanism is discussed. The eddy current damper eliminates the problems associated with the outgassing or leaking of damping fluids. It also provides performance advantages such as damping torque rates, which are truly linear with respect to input speed, continuous 360 degree operation in both directions of rotation, wide operating temperature range, and the capability of convenient adjustment of damping rates by the user without disassembly or special tools.

  5. Development of eddy current probe for fiber orientation assessment in carbon fiber composites

    NASA Astrophysics Data System (ADS)

    Wincheski, Russell A.; Zhao, Selina

    2018-04-01

    Measurement of the fiber orientation in a carbon fiber composite material is crucial in understanding the load carrying capability of the structure. As manufacturing conditions including resin flow and molding pressures can alter fiber orientation, verification of the as-designed fiber layup is necessary to ensure optimal performance of the structure. In this work, the development of an eddy current probe and data processing technique for analysis of fiber orientation in carbon fiber composites is presented. A proposed directional eddy current probe is modeled and its response to an anisotropic multi-layer conductor simulated. The modeling results are then used to finalize specifications of the eddy current probe. Experimental testing of the fabricated probe is presented for several samples including a truncated pyramid part with complex fiber orientation draped to the geometry for resin transfer molding. The inductively coupled single sided measurement enables fiber orientation characterization through the thickness of the part. The fast and cost-effective technique can be applied as a spot check or as a surface map of the fiber orientations across the structure. This paper will detail the results of the probe design, computer simulations, and experimental results.

  6. A western boundary current eddy characterisation study

    NASA Astrophysics Data System (ADS)

    Ribbe, Joachim; Brieva, Daniel

    2016-12-01

    The analysis of an eddy census for the East Australian Current (EAC) region yielded a total of 497 individual short-lived (7-28 days) cyclonic and anticyclonic eddies for the period 1993 to 2015. This was an average of about 23 eddies per year. 41% of the tracked individual cyclonic and anticyclonic eddies were detected off southeast Queensland between about 25 °S and 29 °S. This is the region where the flow of the EAC intensifies forming a swift western boundary current that impinges near Fraser Island on the continental shelf. This zone was also identified as having a maximum in detected short-lived cyclonic eddies. A total of 94 (43%) individual cyclonic eddies or about 4-5 per year were tracked in this region. The census found that these potentially displaced entrained water by about 115 km with an average displacement speed of about 4 km per day. Cyclonic eddies were likely to contribute to establishing an on-shelf longshore northerly flow forming the western branch of the Fraser Island Gyre and possibly presented an important cross-shelf transport process in the life cycle of temperate fish species of the EAC domain. In-situ observations near western boundary currents previously documented the entrainment, off-shelf transport and export of near shore water, nutrients, sediments, fish larvae and the renewal of inner shelf water due to short-lived eddies. This study found that these cyclonic eddies potentially play an important off-shelf transport process off the central east Australian coast.

  7. Processing techniques for correlation of LDA and thermocouple signals

    NASA Astrophysics Data System (ADS)

    Nina, M. N. R.; Pita, G. P. A.

    1986-11-01

    A technique was developed to enable the evaluation of the correlation between velocity and temperature, with laser Doppler anemometer (LDA) as the source of velocity signals and fine wire thermocouple as that of flow temperature. The discontinuous nature of LDA signals requires a special technique for correlation, in particular when few seeding particles are present in the flow. The thermocouple signal was analog compensated in frequency and the effect of the value of time constant on the velocity temperature correlation was studied.

  8. Baroclinic Adjustment of the Eddy-Driven Jet

    NASA Astrophysics Data System (ADS)

    Novak, Lenka; Ambaum, Maarten H. P.; Harvey, Ben J.

    2017-04-01

    The prediction of poleward shift in the midlatitude eddy-driven jets due to anthropogenic climate change is now a robust feature of climate models, but the magnitude of this shift or the processes responsible for it are less certain. This uncertainty comes from the complex response in storm tracks to large-scale forcing and their nonlinear modulation of the jet. This study uses global circulation models to reveal a relationship between eddy growth rate (referred to as baroclinicity) and eddy activity, whereby baroclinicity responds most rapidly to an eddy-dissipating forcing whereas eddy activity responds most rapidly to a baroclinicity-replenishing forcing. This nonlinearity can be generally explained using a two-dimensional dynamical system essentially describing the baroclinic adjustment as a predator-prey relationship. Despite this nonlinearity, the barotropic changes in the eddy-driven jet appear to be of a comparable magnitude for the ranges of both types of forcing tested in this study. It is implied that while changes in eddy activity or baroclinicity may indicate the sign of latitudinal jet shifting, the precise magnitude of this shifting is a result of a balance between these two quantities.

  9. Wind Forced Variability in Eddy Formation, Eddy Shedding, and the Separation of the East Australian Current

    NASA Astrophysics Data System (ADS)

    Bull, Christopher Y. S.; Kiss, Andrew E.; Jourdain, Nicolas C.; England, Matthew H.; van Sebille, Erik

    2017-12-01

    The East Australian Current (EAC), like many other subtropical western boundary currents, is believed to be penetrating further poleward in recent decades. Previous observational and model studies have used steady state dynamics to relate changes in the westerly winds to changes in the separation behavior of the EAC. As yet, little work has been undertaken on the impact of forcing variability on the EAC and Tasman Sea circulation. Here using an eddy-permitting regional ocean model, we present a suite of simulations forced by the same time-mean fields, but with different atmospheric and remote ocean variability. These eddy-permitting results demonstrate the nonlinear response of the EAC to variable, nonstationary inhomogeneous forcing. These simulations show an EAC with high intrinsic variability and stochastic eddy shedding. We show that wind stress variability on time scales shorter than 56 days leads to increases in eddy shedding rates and southward eddy propagation, producing an increased transport and southward reach of the mean EAC extension. We adopt an energetics framework that shows the EAC extension changes to be coincident with an increase in offshore, upstream eddy variance (via increased barotropic instability) and increase in subsurface mean kinetic energy along the length of the EAC. The response of EAC separation to regional variable wind stress has important implications for both past and future climate change studies.

  10. Methane Emissions Estimation from a Dairy Farm using Eddy Covariance Measurements

    NASA Astrophysics Data System (ADS)

    Guo, Q.; Richardson, S.; Sokol, A. B.; Lauvaux, T.; Hristov, A. N.; Hong, B.; Davis, K. J.

    2017-12-01

    Dairy farms are a significant source of methane emissions. Accurate quantification of these emissions is important for evaluating and ultimately minimizing the impact of agricultural activity on climate change. We have employed the eddy covariance (EC) technique to attempt to quantify total CH4 emissions from a dairy farm, and compare these emissions to inventory estimates. An eddy covariance (EC) sensor was deployed to monitor CH4 emissions at one dairy manure storage facility from July 2016 through the winter of 2017, at a second manure storage facility from April to mid-July 2017, and at dairy barns during July and August of 2017. A flux footprint model was used to convert the observed methane fluxes into estimates of emissions per unit area from these sources. During April and May, CH4 fluxes from the second lagoon were relatively small and slowly increased with daily mean values growing from 0.45 to 10.75 μmol m-2 s-1. June to mid-July fluxes increased rapidly with a peak daily mean emission of 77.97 μmol m-2 s-1. The fluxes were positively correlated with air temperature. Comparison of emissions from the two lagoons, comparison to an inventory estimate of emissions from these lagoons, and evaluation of methane emissions from the barns are underway. These results will be combined to evaluate total farm emissions, and to test our understanding of the factors that govern emissions from dairy operations.

  11. Rapid Measurement and Correction of Phase Errors from B0 Eddy Currents: Impact on Image Quality for Non-Cartesian Imaging

    PubMed Central

    Brodsky, Ethan K.; Klaers, Jessica L.; Samsonov, Alexey A.; Kijowski, Richard; Block, Walter F.

    2014-01-01

    Non-Cartesian imaging sequences and navigational methods can be more sensitive to scanner imperfections that have little impact on conventional clinical sequences, an issue which has repeatedly complicated the commercialization of these techniques by frustrating transitions to multi-center evaluations. One such imperfection is phase errors caused by resonant frequency shifts from eddy currents induced in the cryostat by time-varying gradients, a phenomemon known as B0 eddy currents. These phase errors can have a substantial impact on sequences that use ramp sampling, bipolar gradients, and readouts at varying azimuthal angles. We present a method for measuring and correcting phase errors from B0 eddy currents and examine the results on two different scanner models. This technique yields significant improvements in image quality for high-resolution joint imaging on certain scanners. The results suggest that correction of short time B0 eddy currents in manufacturer provided service routines would simplify adoption of non-Cartesian sampling methods. PMID:22488532

  12. Effects of eddy initial conditions on nonlinear forcing of planetary scale waves by amplifying baroclinic eddies

    NASA Technical Reports Server (NTRS)

    Young, Richard E.

    1986-01-01

    The previous study of Young and Villere concerning growth of planetary scale waves forced by wave-wave interactions of amplifying intermediate scale baroclinic eddies is extended to investigate effects of different eddy initial conditions. A global, spectral, primitive equation model is used for the calculations. For every set of eddy initial conditions considered, growth rates of planetary modes are considerably greater than growth rates computed from linear instability theory for a fixed zonally independent basic state. However, values of growth rates ranged over a factor of 3 depending on the particular set of eddy initial conditions used. Nonlinear forcing of planetary modes via wave-wave coupling becomes more important than baroclinic growth on the basic state at small values of the intermediate-scale modal amplitudes. The relative importance of direct transfer of kinetic energy from intermediate scales of motion to a planetary mode, compared to baroclinic conversion of available potential energy to kinetic energy within that planetary mode, depends on the individual case. In all cases, however, the transfer of either kinetic or available potential energy to the planetary modes was accomplished principally by wave-wave transfer from intermediate scale eddies, rather than from the zonally averaged state. The zonal wavenumber 2 planetary mode was prominent in all solutions, even in those for which eddy initial conditions were such that a different planetary mode was selectively forced at the start. General characteristics of the structural evolution of the planetary wave components of total heat and momentum flux, and modal structures themselves, were relatively insensitive to variations in eddy initial conditions, even though quantitative details varied from case to case.

  13. Detection of Anomalous Machining Damages in Inconel 718 and TI 6-4 by Eddy Current Techniques

    NASA Astrophysics Data System (ADS)

    Lo, C. C. H.; Shimon, M.; Nakagawa, N.

    2010-02-01

    This paper reports on an eddy current (EC) study aimed at detecting anomalous machining damages in Inconel 718 and Ti 6-4 samples, including (i) surface discontinuities such as re-depositing of chips onto the machined surface, and (ii) microstructural damages manifested as a white surface layer and a subsurface layer of distorted grains, typically tens of microns thick. A series of pristine and machine-damaged coupons were studied by EC scans using a differential probe operated at 2 MHz to detect discontinuous surface anomalies, and by swept high frequency EC (SHFEC) measurements from 0.5 MHz to 65.5 MHz using proprietary detection coils to detect surface microstructural damages. In general, the EC c-scan data from machine-damaged surfaces show spatial variations with larger standard deviations than those from the undamaged surfaces. In some cases, the c-scan images exhibit characteristic bipolar indications in good spatial correlation with surface anomalies revealed by optical microscopy and laser profilometry. Results of the SHFEC measurements indicate a reduced near-surface conductivity of the damaged surfaces compared to the undamaged surfaces.

  14. Eddies off the Queen Charlotte Islands

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The bright red, green, and turquoise patches to the west of British Columbia's Queen Charlotte Islands and Alaska's Alexander Archipelago highlight the presence of biological activity in the ocean. These colors indicate high concentrations of chlorophyll, the primary pigment found in phytoplankton. Notice that there are a number of eddies visible in the Pacific Ocean in this pseudo-color scene. The eddies are formed by strong outflow currents from rivers along North America's west coast that are rich in nutrients from the springtime snowmelt running off the mountains. This nutrient-rich water helps stimulate the phytoplankton blooms within the eddies. (For more details, read Tracking Eddies that Feed the Sea.) To the west of the eddies in the water, another type of eddy-this one in the atmosphere-forms the clouds into the counterclockwise spiral characteristic of a low pressure system in the Northern Hemisphere. (Click on the image above to see it at full resolution; or click to see the scene in true-color.) The snow-covered mountains of British Columbia are visible in the upper righthand corner of the image. This scene was constructed using SeaWiFS data collected on June 13, 2002. SeaWiFS image courtesy the SeaWiFS Project, NASA/Goddard Space Flight Center, and ORBIMAGE

  15. Eddy Covariance Method for CO2 Emission Measurements: CCS Applications, Principles, Instrumentation and Software

    NASA Astrophysics Data System (ADS)

    Burba, George; Madsen, Rod; Feese, Kristin

    2013-04-01

    The Eddy Covariance method is a micrometeorological technique for direct high-speed measurements of the transport of gases, heat, and momentum between the earth's surface and the atmosphere. Gas fluxes, emission and exchange rates are carefully characterized from single-point in-situ measurements using permanent or mobile towers, or moving platforms such as automobiles, helicopters, airplanes, etc. Since the early 1990s, this technique has been widely used by micrometeorologists across the globe for quantifying CO2 emission rates from various natural, urban and agricultural ecosystems [1,2], including areas of agricultural carbon sequestration. Presently, over 600 eddy covariance stations are in operation in over 120 countries. In the last 3-5 years, advancements in instrumentation and software have reached the point when they can be effectively used outside the area of micrometeorology, and can prove valuable for geological carbon capture and sequestration, landfill emission measurements, high-precision agriculture and other non-micrometeorological industrial and regulatory applications. In the field of geological carbon capture and sequestration, the magnitude of CO2 seepage fluxes depends on a variety of factors. Emerging projects utilize eddy covariance measurement to monitor large areas where CO2 may escape from the subsurface, to detect and quantify CO2 leakage, and to assure the efficiency of CO2 geological storage [3,4,5,6,7,8]. Although Eddy Covariance is one of the most direct and defensible ways to measure and calculate turbulent fluxes, the method is mathematically complex, and requires careful setup, execution and data processing tailor-fit to a specific site and a project. With this in mind, step-by-step instructions were created to introduce a novice to the conventional Eddy Covariance technique [9], and to assist in further understanding the method through more advanced references such as graduate-level textbooks, flux networks guidelines, journals

  16. Determination of eddy current response with magnetic measurements.

    PubMed

    Jiang, Y Z; Tan, Y; Gao, Z; Nakamura, K; Liu, W B; Wang, S Z; Zhong, H; Wang, B B

    2017-09-01

    Accurate mutual inductances between magnetic diagnostics and poloidal field coils are an essential requirement for determining the poloidal flux for plasma equilibrium reconstruction. The mutual inductance calibration of the flux loops and magnetic probes requires time-varying coil currents, which also simultaneously drive eddy currents in electrically conducting structures. The eddy current-induced field appearing in the magnetic measurements can substantially increase the calibration error in the model if the eddy currents are neglected. In this paper, an expression of the magnetic diagnostic response to the coil currents is used to calibrate the mutual inductances, estimate the conductor time constant, and predict the eddy currents response. It is found that the eddy current effects in magnetic signals can be well-explained by the eddy current response determination. A set of experiments using a specially shaped saddle coil diagnostic are conducted to measure the SUNIST-like eddy current response and to examine the accuracy of this method. In shots that include plasmas, this approach can more accurately determine the plasma-related response in the magnetic signals by eliminating the field due to the eddy currents produced by the external field.

  17. Eddy-Current Inspection Of Graphite-Fiber Composites

    NASA Technical Reports Server (NTRS)

    Workman, G. L.; Bryson, C. C.

    1993-01-01

    NASA technical memorandum describes initial research on, and proposed development of, automated system for nondestructive eddy-current inspection of parts made of graphite-fiber/epoxy-matrix composite materials. Sensors in system E-shaped or U-shaped eddy-current probes like those described in "Eddy-Current Probes For Inspecting Graphite-Fiber Composites" (MFS-26129).

  18. Eddy Generation and Shedding in a Tidally Energetic Channel

    NASA Astrophysics Data System (ADS)

    McIlvenny, J.; Gillibrand, P. A.; Walters, R. A.

    2016-02-01

    The Pentland Firth in northern Scotland, and its subsidiary channel the Inner Sound, are currently under scrutiny as the first tidal energy array in the world is installed during 2016. The tidal flows in the channel and sound have been intensively observed and modelled in recent years, and the turbulent nature of the flow, with features of eddy generation and shedding, is becoming increasingly well known. Turbulence and eddies pose potential risks to the turbine infrastructure through enhanced stress on the blades, while understanding environmental effects of energy extraction also requires accurate simulation of the hydrodynamics of the flow. Here, we apply a mixed finite element/finite volume hydrodynamic model to the northern Scottish shelf, with a particular focus on flows through the Pentland Firth and the Inner Sound. We use an unstructured grid model, which allows the open boundaries to be far removed from the region of interest, while still allowing a grid spacing of 40m in the Inner Sound. The model employs semi-implicit techniques to solve the momentum and free surface equations, and semi-Lagrangian methods to solve the material derivative in the momentum equation, making it fast, robust and accurate and suitable for simulating flows in irregular coastal ocean environments. The model is well suited to address questions relating to tidal energy potential. We present numerical simulations of tidal currents in The Pentland Firth and Inner Sound. Observed velocities in the Inner Sound, measured by moored ADCP deployments, reach speeds of up to 5 m s-1 and the model successfully reproduces these strong currents. In the simulations, eddies are formed by interactions between the strong flow and the northern and southern headlands on the island of Stroma; some of these eddies are trapped and remain locked in position, whereas others are shed and transported away from the generation zone. We track the development and advection of eddies in relation to the site of

  19. Carbon dioxide and water vapor fluxes over Erhai Lake using eddy covariance technique

    NASA Astrophysics Data System (ADS)

    Feng, J.; Liu, H.; Sun, J.

    2012-12-01

    The lakes have significant impacts on the local or even regional weather and climate. However, the effect of lakes is poorly parameterized in numerical weather prediction and climate models until now. In this background, an eddy covariance measurement site was built to directly measure long-term turbulent fluxes of water vapor and CO2 over Erhai Lake (area 250 km2, maximum depth 21.5 m) in the Southwest part of China. This study aimed at getting better understands on the air-lake interaction that in turn may benefit the parameterization schemes in the models. The observations also included radiation, wind speed, direction, and water temperature profile measurements. Using a whole year data in 2011, the diurnal variation patterns of sensible heat, latent heat and CO2 fluxes were investigated. The sensible heat flux peaked in early morning (about 25 W m-2) and reached its minimum in the afternoon (about -15 W m-2), and was strongly controlled by the air-water temperature difference. The latent had an opposite diurnal course with a maximum in the afternoon (about 150 W m-2) and minimum in the morning (about 5 W m-2), which was correlated with water pressure deficit and wind speed. The CO2 fluxes were positive at night (about 2.1 μmol m-2 s-1), and weakly negative (about -1.0 μmol m-2 s-1) in the afternoon (14:00-16:00). In the seasonal time scale, the lake was a weak CO2 sink in the summer, but a CO2 source in the other time of the year. In order to analyze energy balance, heat storage of water was estimated using water temperature profile data. The result showed that the average energy balance closure was about 85% in the summer, and about 78% in the other time of the year. The minimum values of albedo were observed to be about 0.05 at midday, indicating a large part of solar radiation was absorbed by the water. The aerodynamic roughness length (z0) and bulk transfer coefficients (Cd, Ch and Cq) were also estimated using eddy covariance data. The average value of z

  20. The decay of a simple eddy

    NASA Technical Reports Server (NTRS)

    Bateman, H

    1923-01-01

    The principal result obtained in this report is a generalization of Taylor's formula for a simple eddy. The discussion of the properties of the eddy indicates that there is a slight analogy between the theory of eddies in a viscous fluid and the quantum theory of radiation. Another exact solution of the equations of motion of viscous fluid yields a result which reminds one of the well-known condition for instability in the case of a horizontally stratified atmosphere.

  1. Parameter studies on the energy balance closure problem using large-eddy simulation

    NASA Astrophysics Data System (ADS)

    De Roo, Frederik; Banerjee, Tirtha; Mauder, Matthias

    2017-04-01

    The imbalance of the surface energy budget in eddy-covariance measurements is still a pending problem. A possible cause is the presence of land surface heterogeneity. Heterogeneities of the boundary layer scale or larger are most effective in influencing the boundary layer turbulence, and large-eddy simulations have shown that secondary circulations within the boundary layer can affect the surface energy budget. However, the precise influence of the surface characteristics on the energy imbalance and its partitioning is still unknown. To investigate the influence of surface variables on all the components of the flux budget under convective conditions, we set up a systematic parameter study by means of large-eddy simulation. For the study we use a virtual control volume approach, and we focus on idealized heterogeneity by considering spatially variable surface fluxes. The surface fluxes vary locally in intensity and these patches have different length scales. The main focus lies on heterogeneities of length scales of the kilometer scale and one decade smaller. For each simulation, virtual measurement towers are positioned at functionally different positions. We discriminate between the locally homogeneous towers, located within land use patches, with respect to the more heterogeneous towers, and find, among others, that the flux-divergence and the advection are strongly linearly related within each class. Furthermore, we seek correlators for the energy balance ratio and the energy residual in the simulations. Besides the expected correlation with measurable atmospheric quantities such as the friction velocity, boundary-layer depth and temperature and moisture gradients, we have also found an unexpected correlation with the temperature difference between sonic temperature and surface temperature. In additional simulations with a large number of virtual towers, we investigate higher order correlations, which can be linked to secondary circulations. In a companion

  2. Eddy Covariance Flux Measurements of Pollutant Gases in the Mexico City Urban Area: a Useful Technique to Evaluate Emissions inventories

    NASA Astrophysics Data System (ADS)

    Velasco, E.; Grivicke, R.; Pressley, S.; Allwine, G.; Jobson, T.; Westberg, H.; Lamb, B.; Ramos, R.; Molina, L.

    2007-12-01

    Direct measurements of emissions of pollutant gases that include all major and minor emissions sources in urban areas are a missing requirement to improve and evaluate emissions inventories. The quality of an urban emissions inventory relies on the accuracy of the information of anthropogenic activities, which in many cases is not available, in particular in urban areas of developing countries. As part of the MCMA-2003 field campaign, we demonstrated the feasibility of using eddy covariance (EC) techniques coupled with fast-response sensors to measure fluxes of volatile organic compounds (VOCs) and CO2 from a residential district of Mexico City. Those flux measurements demonstrated to be also a valuable tool to evaluate the emissions inventory used for air quality modeling. With the objective to confirm the representativeness of the 2003 flux measurements in terms of magnitude, composition and diurnal distribution, as well to evaluate the most recent emissions inventory, a second flux system was deployed in a different district of Mexico City during the 2006 MILAGRO field campaign. This system was located in a busy district surrounded by congested avenues close to the center of the city. In 2003 and 2006 fluxes of olefins and CO2 were measured by the EC technique using a Fast Isoprene Sensor calibrated with a propylene standard and an open path Infrared Gas Analyzer (IRGA), respectively. Fluxes of aromatic and oxygenated VOCs were analyzed by Proton Transfer Reaction-Mass Spectroscopy (PTR-MS) and the disjunct eddy covariance (DEC) technique. In 2006 the number of VOCs was extended using a disjunct eddy accumulation (DEA) system. This system collected whole air samples as function of the direction of the vertical wind component, and the samples were analyzed on site by gas chromatography / flame ionization detection (GC-FID). In both studies we found that the urban surface is a net source of CO2 and VOCs. The diurnal patterns were similar, but the 2006 fluxes

  3. Coherent mesoscale eddies in the North Atlantic subtropical gyre: 3-D structure and transport with application to the salinity maximum

    NASA Astrophysics Data System (ADS)

    Amores, Angel; Melnichenko, Oleg; Maximenko, Nikolai

    2017-01-01

    The mean vertical structure and transport properties of mesoscale eddies are investigated in the North Atlantic subtropical gyre by combining historical records of Argo temperature/salinity profiles and satellite sea level anomaly data in the framework of the eddy tracking technique. The study area is characterized by a low eddy kinetic energy and sea surface salinity maximum. Although eddies have a relatively weak signal at surface (amplitudes around 3-7 cm), the eddy composites reveal a clear deep signal that penetrates down to at least 1200 m depth. The analysis also reveals that the vertical structure of the eddy composites is strongly affected by the background stratification. The horizontal patterns of temperature/salinity anomalies can be reconstructed by a linear combination of a monopole, related to the elevation/depression of the isopycnals in the eddy core, and a dipole, associated with the horizontal advection of the background gradient by the eddy rotation. A common feature of all the eddy composites reconstructed is the phase coherence between the eddy temperature/salinity and velocity anomalies in the upper ˜300 m layer, resulting in the transient eddy transports of heat and salt. As an application, a box model of the near-surface layer is used to estimate the role of mesoscale eddies in maintaining a quasi-steady state distribution of salinity in the North Atlantic subtropical salinity maximum. The results show that mesoscale eddies are able to provide between 4 and 21% of the salt flux out of the area required to compensate for the local excess of evaporation over precipitation.

  4. Eddy-Kuroshio Interactions: Local and Remote Effects

    NASA Astrophysics Data System (ADS)

    Jan, Sen; Mensah, Vigan; Andres, Magdalena; Chang, Ming-Huei; Yang, Yiing Jang

    2017-12-01

    Quasi-geostrophic mesoscale eddies regularly impinge on the Kuroshio in the western North Pacific, but the processes underlying the evolution of these eddy-Kuroshio interactions have not yet been thoroughly investigated in the literature. Here this interaction is examined with results from a semi-idealized three-dimensional numerical model and observations from four pressure-sensor equipped inverted echo sounders (PIESs) in a zonal section east of Taiwan and satellite altimeters. Both the observations and numerical simulations suggest that, during the interaction of a cyclonic eddy with the Kuroshio, the circular eddy is deformed into an elliptic shape with the major axis in the northwest-southeast direction, before being dissipated; the poleward velocity and associated Kuroshio transport decrease and the sea level and pycnocline slopes across the Kuroshio weaken. In contrast, for an anticyclonic eddy during the eddy-Kuroshio interaction, variations in the velocity, sea level, and isopycnal depth are reversed; the circular eddy is also deformed to an ellipse but with the major axis parallel to the Kuroshio. The model results also demonstrate that the velocity field is modified first and consequently the SSH and isopycnal depth evolve during the interaction. Furthermore, due to the combined effect of impingement latitude and realistic topography, some eddy-Kuroshio interactions east of Taiwan are found to have remote effects, both in the Luzon Strait and on the East China Sea shelf northeast of Taiwan.Plain Language SummaryMesoscale <span class="hlt">eddies</span> are everywhere in the ocean. These ocean swirls of either clockwise or counterclockwise spinning with diameter of about 100-300 km and rounding current speed of about 0.5 m/s, carrying energy and certain type of water mass, move westward and eventually reach the western boundary of each ocean. The evolution of these <span class="hlt">eddies</span> and the interaction which occurs when they encounter the western</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27717291','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27717291"><span>Turbulent <span class="hlt">eddy</span> diffusion models in exposure assessment - Determination of the <span class="hlt">eddy</span> diffusion coefficient.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Shao, Yuan; Ramachandran, Sandhya; Arnold, Susan; Ramachandran, Gurumurthy</p> <p>2017-03-01</p> <p>The use of the turbulent <span class="hlt">eddy</span> diffusion model and its variants in exposure assessment is limited due to the lack of knowledge regarding the isotropic <span class="hlt">eddy</span> diffusion coefficient, D T . But some studies have suggested a possible relationship between D T and the air changes per hour (ACH) through a room. The main goal of this study was to accurately estimate D T for a range of ACH values by minimizing the difference between the concentrations measured and predicted by <span class="hlt">eddy</span> diffusion model. We constructed an experimental chamber with a spatial concentration gradient away from the contaminant source, and conducted 27 3-hr long experiments using toluene and acetone under different air flow conditions (0.43-2.89 ACHs). An <span class="hlt">eddy</span> diffusion model accounting for chamber boundary, general ventilation, and advection was developed. A mathematical expression for the slope based on the geometrical parameters of the ventilation system was also derived. There is a strong linear relationship between D T and ACH, providing a surrogate parameter for estimating D T in real-life settings. For the first time, a mathematical expression for the relationship between D T and ACH has been derived that also corrects for non-ideal conditions, and the calculated value of the slope between these two parameters is very close to the experimentally determined value. The values of D T obtained from the experiments are generally consistent with values reported in the literature. They are also independent of averaging time of measurements, allowing for comparison of values obtained from different measurement settings. These findings make the use of turbulent <span class="hlt">eddy</span> diffusion models for exposure assessment in workplace/indoor environments more practical.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018DSRI..131....1C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018DSRI..131....1C"><span>Zonal migration and transport variations of the Kuroshio east of Taiwan induced by <span class="hlt">eddy</span> impingements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chang, Ming-Huei; Jan, Sen; Mensah, Vigan; Andres, Magdalena; Rainville, Luc; Yang, Yiing Jang; Cheng, Yu-Hsin</p> <p>2018-01-01</p> <p>Variability of the Kuroshio east of Taiwan was observed at a cross-stream transect 50 km south of the PCM-1 line with an array of three moored ADCPs measuring for 23 months, supplemented with eleven repeated shipboard surveys. Observations of the Kuroshio's velocity structure reveal the absence of an obvious regular seasonal signal, but significant variability at 70-200 day period for both maximum velocity axis migration and transport due to interactions with mesoscale <span class="hlt">eddies</span>. Empirical orthogonal function (EOF) analysis shows the migration and transport modes explain 46% and 29% of the total variance, respectively, which is in contrast to the findings at the PCM-1 line where the transport mode explained more variance than did the migration mode. The Kuroshio transport in the upper 500 m across a 150 km section is 17.2 Sv with a standard deviation of 5 Sv. The estimated Kuroshio transport is 4.3 Sv lower than that reported for the PCM-1 line, likely due to the interannual variations related to abundance of mesoscale <span class="hlt">eddies</span> in the Subtropical Counter Current (STCC) region. Transport variability east of Taiwan is mostly caused by Kuroshio-<span class="hlt">eddy</span> interactions. When single anticyclonic (cyclonic) <span class="hlt">eddies</span> encounter the Kuroshio, they enhance (reduce) poleward transport, presumably by increasing (decreasing) the sea level anomaly (SLA) along the eastern flank of the Kuroshio (<span class="hlt">correlation</span> = 0.82). When a pair of <span class="hlt">eddies</span> impinges on the Kuroshio, the upstream confluence and diffluence caused by the dipole <span class="hlt">eddies</span> increases and decreases the Kuroshio transport, respectively. Furthermore, the eastward (westward) currents that result from either the single <span class="hlt">eddy</span> or the dipole <span class="hlt">eddy</span> produce flow divergence (convergence) adjacent to the Kuroshio's eastern edge, favoring the offshore (onshore) migration of the Kuroshio axis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OcMod.127....1B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OcMod.127....1B"><span>Dynamically consistent parameterization of mesoscale <span class="hlt">eddies</span>. Part III: Deterministic approach</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berloff, Pavel</p> <p>2018-07-01</p> <p>This work continues development of dynamically consistent parameterizations for representing mesoscale <span class="hlt">eddy</span> effects in non-<span class="hlt">eddy</span>-resolving and <span class="hlt">eddy</span>-permitting ocean circulation models and focuses on the classical double-gyre problem, in which the main dynamic <span class="hlt">eddy</span> effects maintain eastward jet extension of the western boundary currents and its adjacent recirculation zones via <span class="hlt">eddy</span> backscatter mechanism. Despite its fundamental importance, this mechanism remains poorly understood, and in this paper we, first, study it and, then, propose and test its novel parameterization. We start by decomposing the reference <span class="hlt">eddy</span>-resolving flow solution into the large-scale and <span class="hlt">eddy</span> components defined by spatial filtering, rather than by the Reynolds decomposition. Next, we find that the eastward jet and its recirculations are robustly present not only in the large-scale flow itself, but also in the rectified time-mean <span class="hlt">eddies</span>, and in the transient rectified <span class="hlt">eddy</span> component, which consists of highly anisotropic ribbons of the opposite-sign potential vorticity anomalies straddling the instantaneous eastward jet core and being responsible for its continuous amplification. The transient rectified component is separated from the flow by a novel remapping method. We hypothesize that the above three components of the eastward jet are ultimately driven by the small-scale transient <span class="hlt">eddy</span> forcing via the <span class="hlt">eddy</span> backscatter mechanism, rather than by the mean <span class="hlt">eddy</span> forcing and large-scale nonlinearities. We verify this hypothesis by progressively turning down the backscatter and observing the induced flow anomalies. The backscatter analysis leads us to formulating the key <span class="hlt">eddy</span> parameterization hypothesis: in an <span class="hlt">eddy</span>-permitting model at least partially resolved <span class="hlt">eddy</span> backscatter can be significantly amplified to improve the flow solution. Such amplification is a simple and novel <span class="hlt">eddy</span> parameterization framework implemented here in terms of local, deterministic flow roughening controlled by single</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20100042300','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20100042300"><span>Development and Application of Wide Bandwidth Magneto-Resistive Sensor Based <span class="hlt">Eddy</span> Current Probe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wincheski, Russell A.; Simpson, John</p> <p>2010-01-01</p> <p>The integration of magneto-resistive sensors into <span class="hlt">eddy</span> current probes can significantly expand the capabilities of conventional <span class="hlt">eddy</span> current nondestructive evaluation <span class="hlt">techniques</span>. The room temperature solid-state sensors have typical bandwidths in the megahertz range and resolutions of tens of microgauss. The low frequency sensitivity of magneto-resistive sensors has been capitalized upon in previous research to fabricate very low frequency <span class="hlt">eddy</span> current sensors for deep flaw detection in multilayer conductors. In this work a modified probe design is presented to expand the capabilities of the device. The new probe design incorporates a dual induction source enabling operation from low frequency deep flaw detection to high frequency high resolution near surface material characterization. Applications of the probe for the detection of localized near surface conductivity anomalies are presented. Finite element modeling of the probe is shown to be in good agreement with experimental measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMOS31B1402A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMOS31B1402A"><span><span class="hlt">Eddy</span>-induced salinity pattern in the North Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abe, H.; Ebuchi, N.; Ueno, H.; Ishiyama, H.; Matsumura, Y.</p> <p>2017-12-01</p> <p>This research examines spatio-temporal behavior of sea surface salinity (SSS) after intense rainfall events using observed data from Aquarius. Aquarius SSS in the North Pacific reveals one notable event in which SSS is locally freshened by intense rainfall. Although SSS pattern shortly after the rainfall reflects atmospheric pattern, its final form reflects ocean dynamic structure; an anticyclonic <span class="hlt">eddy</span>. Since this anticyclonic <span class="hlt">eddy</span> was located at SSS front created by precipitation, this <span class="hlt">eddy</span> stirs the water in a clockwise direction. This <span class="hlt">eddy</span> stirring was visible for several months. It is expected horizontal transport by mesoscale <span class="hlt">eddies</span> would play significant role in determining upper ocean salinity structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PhFl...28b5102B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PhFl...28b5102B"><span>Turbulent <span class="hlt">eddies</span> in a compressible jet in crossflow measured using pulse-burst particle image velocimetry</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Beresh, Steven J.; Wagner, Justin L.; Henfling, John F.; Spillers, Russell W.; Pruett, Brian O. M.</p> <p>2016-02-01</p> <p>Pulse-burst Particle Image Velocimetry (PIV) has been employed to acquire time-resolved data at 25 kHz of a supersonic jet exhausting into a subsonic compressible crossflow. Data were acquired along the windward boundary of the jet shear layer and used to identify turbulent <span class="hlt">eddies</span> as they convect downstream in the far-field of the interaction. <span class="hlt">Eddies</span> were found to have a tendency to occur in closely spaced counter-rotating pairs and are routinely observed in the PIV movies, but the variable orientation of these pairs makes them difficult to detect statistically. <span class="hlt">Correlated</span> counter-rotating vortices are more strongly observed to pass by at a larger spacing, both leading and trailing the reference <span class="hlt">eddy</span>. This indicates the paired nature of the turbulent <span class="hlt">eddies</span> and the tendency for these pairs to recur at repeatable spacing. Velocity spectra reveal a peak at a frequency consistent with this larger spacing between shear-layer vortices rotating with identical sign. The spatial scale of these vortices appears similar to previous observations of compressible jets in crossflow. Super-sampled velocity spectra to 150 kHz reveal a power-law dependency of -5/3 in the inertial subrange as well as a -1 dependency at lower frequencies attributed to the scales of the dominant shear-layer <span class="hlt">eddies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/869453','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/869453"><span>Expert system for analyzing <span class="hlt">eddy</span> current measurements</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Levy, Arthur J.; Oppenlander, Jane E.; Brudnoy, David M.; Englund, James M.; Loomis, Kent C.</p> <p>1994-01-01</p> <p>A method and apparatus (called DODGER) analyzes <span class="hlt">eddy</span> current data for heat exchanger tubes or any other metallic object. DODGER uses an expert system to analyze <span class="hlt">eddy</span> current data by reasoning with uncertainty and pattern recognition. The expert system permits DODGER to analyze <span class="hlt">eddy</span> current data intelligently, and obviate operator uncertainty by analyzing the data in a uniform and consistent manner.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70026856','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70026856"><span>Optimizing <span class="hlt">correlation</span> <span class="hlt">techniques</span> for improved earthquake location</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Schaff, D.P.; Bokelmann, G.H.R.; Ellsworth, W.L.; Zanzerkia, E.; Waldhauser, F.; Beroza, G.C.</p> <p>2004-01-01</p> <p>Earthquake location using relative arrival time measurements can lead to dramatically reduced location errors and a view of fault-zone processes with unprecedented detail. There are two principal reasons why this approach reduces location errors. The first is that the use of differenced arrival times to solve for the vector separation of earthquakes removes from the earthquake location problem much of the error due to unmodeled velocity structure. The second reason, on which we focus in this article, is that waveform cross <span class="hlt">correlation</span> can substantially reduce measurement error. While cross <span class="hlt">correlation</span> has long been used to determine relative arrival times with subsample precision, we extend <span class="hlt">correlation</span> measurements to less similar waveforms, and we introduce a general quantitative means to assess when <span class="hlt">correlation</span> data provide an improvement over catalog phase picks. We apply the <span class="hlt">technique</span> to local earthquake data from the Calaveras Fault in northern California. Tests for an example streak of 243 earthquakes demonstrate that relative arrival times with normalized cross <span class="hlt">correlation</span> coefficients as low as ???70%, interevent separation distances as large as to 2 km, and magnitudes up to 3.5 as recorded on the Northern California Seismic Network are more precise than relative arrival times determined from catalog phase data. Also discussed are improvements made to the <span class="hlt">correlation</span> <span class="hlt">technique</span> itself. We find that for large time offsets, our implementation of time-domain cross <span class="hlt">correlation</span> is often more robust and that it recovers more observations than the cross spectral approach. Longer time windows give better results than shorter ones. Finally, we explain how thresholds and empirical weighting functions may be derived to optimize the location procedure for any given region of interest, taking advantage of the respective strengths of diverse <span class="hlt">correlation</span> and catalog phase data on different length scales.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998JGR...10313145G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998JGR...10313145G"><span><span class="hlt">Eddy</span> covariance measurement of isoprene fluxes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guenther, Alex B.; Hills, Alan J.</p> <p>1998-06-01</p> <p>A system has been developed to directly measure isoprene flux above a forest canopy by <span class="hlt">eddy</span> covariance using the combination of a fast response, real-time isoprene sensor and sonic anemometer. This system is suitable for making nearly unattended, long-term, and continuous measurements of isoprene fluxes. Isoprene detection is based on chemiluminescence between isoprene and reactant ozone, which produces green light at 500 nm. The sensor has a noise level (1σ) of 450 pptv for a 1-s integration which is dominated by random high-frequency noise that does not significantly degrade <span class="hlt">eddy</span> covariance flux measurements. Interference from the flux of other compounds is primarily due to the emission of monoterpenes, propene, ethene, and methyl butenol and the deposition of methacrolein and methyl vinyl ketone. The average total interference for North American landscapes in midday summer is estimated to be about 5% for emissions and -3% for deposition fluxes. In only a few North American landscapes, where isoprene emissions are very low and methyl butenol emissions are high, are interferences predicted to be significant. The system was field tested on a tower above a mixed deciduous forest canopy (Duke Forest, North Carolina, U.S.A.) dominated by oak trees, which are strong isoprene emitters. Isoprene fluxes were estimated for 307 half-hour sampling periods over 10 days. Daytime fluxes ranging from 1 to 14 mg C m-2 h-1 were strongly <span class="hlt">correlated</span> with light and temperature. The daytime mean flux of 6 mg C m-2 h-1 is similar to previous estimates determined by relaxed <span class="hlt">eddy</span> accumulation by Geron et al [1997] at this site. Nighttime fluxes were near zero (0.01±0.03 mg C m-2 h-1).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPC.1806k0002G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPC.1806k0002G"><span>Determining confounding sensitivities in <span class="hlt">eddy</span> current thin film measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gros, Ethan; Udpa, Lalita; Smith, James A.; Wachs, Katelyn</p> <p>2017-02-01</p> <p><span class="hlt">Eddy</span> current (EC) <span class="hlt">techniques</span> are widely used in industry to measure the thickness of non-conductive films on a metal substrate. This is done by using a system whereby a coil carrying a high-frequency alternating current is used to create an alternating magnetic field at the surface of the instrument's probe. When the probe is brought near a conductive surface, the alternating magnetic field will induce ECs in the conductor. The substrate characteristics and the distance of the probe from the substrate (the coating thickness) affect the magnitude of the ECs. The induced currents load the probe coil affecting the terminal impedance of the coil. The measured probe impedance is related to the lift off between coil and conductor as well as conductivity of the test sample. For a known conductivity sample, the probe impedance can be converted into an equivalent film thickness value. The EC measurement can be confounded by a number of measurement parameters. It was the goal of this research to determine which physical properties of the measurement set-up and sample can adversely affect the thickness measurement. The <span class="hlt">eddy</span>-current testing was performed using a commercially available, hand-held <span class="hlt">eddy</span>-current probe (ETA3.3H spring-loaded <span class="hlt">eddy</span> probe running at 8 MHz) that comes with a stand to hold the probe. The stand holds the probe and adjusts the probe on the z-axis to help position the probe in the correct area as well as make precise measurements. The signal from the probe was sent to a hand-held readout, where the results are recorded directly in terms of liftoff or film thickness. Understanding the effect of certain factors on the measurements of film thickness, will help to evaluate how accurate the ETA3.3H spring-loaded <span class="hlt">eddy</span> probe was at measuring film thickness under varying experimental conditions. This research studied the effects of a number of factors such as i) conductivity, ii) edge effect, iii) surface finish of base material and iv) cable condition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........40Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........40Z"><span>A Study of the Southern Ocean: Mean State, <span class="hlt">Eddy</span> Genesis & Demise, and Energy Pathways</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zajaczkovski, Uriel</p> <p></p> <p>The Southern Ocean (SO), due to its deep penetrating jets and <span class="hlt">eddies</span>, is well-suited for studies that combine surface and sub-surface data. This thesis explores the use of Argo profiles and sea surface height ( SSH) altimeter data from a statistical point of view. A linear regression analysis of SSH and hydrographic data reveals that the altimeter can explain, on average, about 35% of the variance contained in the hydrographic fields and more than 95% if estimated locally. <span class="hlt">Correlation</span> maxima are found at mid-depth, where dynamics are dominated by geostrophy. Near the surface, diabatic processes are significant, and the variance explained by the altimeter is lower. Since SSH variability is associated with <span class="hlt">eddies</span>, the regression of SSH with temperature (T) and salinity (S) shows the relative importance of S vs T in controlling density anomalies. The AAIW salinity minimum separates two distinct regions; above the minimum density changes are dominated by T, while below the minimum S dominates over T. The regression analysis provides a method to remove <span class="hlt">eddy</span> variability, effectively reducing the variance of the hydrographic fields. We use satellite altimetry and output from an assimilating numerical model to show that the SO has two distinct <span class="hlt">eddy</span> motion regimes. North and south of the Antarctic Circumpolar Current (ACC), <span class="hlt">eddies</span> propagate westward with a mean meridional drift directed poleward for cyclonic <span class="hlt">eddies</span> (CEs) and equatorward for anticyclonic <span class="hlt">eddies</span> (AEs). <span class="hlt">Eddies</span> formed within the boundaries of the ACC have an effective eastward propagation with respect to the mean deep ACC flow, and the mean meridional drift is reversed, with warm-core AEs propagating poleward and cold-core CEs propagating equatorward. This circulation pattern drives downgradient <span class="hlt">eddy</span> heat transport, which could potentially transport a significant fraction (24 to 60 x 1013 W) of the net poleward ACC <span class="hlt">eddy</span> heat flux. We show that the generation of relatively large amplitude <span class="hlt">eddies</span> is not a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008PhFl...20b6602V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008PhFl...20b6602V"><span>Dipolar <span class="hlt">eddies</span> in a decaying stratified turbulent flow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Voropayev, S. I.; Fernando, H. J. S.; Morrison, R.</p> <p>2008-02-01</p> <p>Laboratory experiments on the evolution of dipolar (momentum) <span class="hlt">eddies</span> in a stratified fluid in the presence of random background motions are described. A turbulent jet puff was used to generate the momentum <span class="hlt">eddies</span>, and a decaying field of ambient random vortical motions was generated by a towed grid. Data on vorticity/velocity fields of momentum <span class="hlt">eddies</span>, those of background motions, and their interactions were collected in the presence and absence of the other, and the main characteristics thereof were parametrized. Similarity arguments predict that dipolar <span class="hlt">eddies</span> in stratified fluids may preserve their identity in decaying grid-generated stratified turbulence, which was verified experimentally. Possible applications of the results include mushroomlike currents and other naturally/artificially generated large dipolar <span class="hlt">eddies</span> in strongly stratified layers of the ocean, the longevity of which is expected to be determined by the characteristics of the <span class="hlt">eddies</span> and random background motions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JPhD...42g5001E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JPhD...42g5001E"><span>A novel <span class="hlt">eddy</span> current damper: theory and experiment</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ebrahimi, Babak; Khamesee, Mir Behrad; Golnaraghi, Farid</p> <p>2009-04-01</p> <p>A novel <span class="hlt">eddy</span> current damper is developed and its damping characteristics are studied analytically and experimentally. The proposed <span class="hlt">eddy</span> current damper consists of a conductor as an outer tube, and an array of axially magnetized ring-shaped permanent magnets separated by iron pole pieces as a mover. The relative movement of the magnets and the conductor causes the conductor to undergo motional <span class="hlt">eddy</span> currents. Since the <span class="hlt">eddy</span> currents produce a repulsive force that is proportional to the velocity of the conductor, the moving magnet and the conductor behave as a viscous damper. The <span class="hlt">eddy</span> current generation causes the vibration to dissipate through the Joule heating generated in the conductor part. An accurate, analytical model of the system is obtained by applying electromagnetic theory to estimate the damping properties of the proposed <span class="hlt">eddy</span> current damper. A prototype <span class="hlt">eddy</span> current damper is fabricated, and experiments are carried out to verify the accuracy of the theoretical model. The experimental test bed consists of a one-degree-of-freedom vibration isolation system and is used for the frequency and transient time response analysis of the system. The <span class="hlt">eddy</span> current damper model has a 0.1 m s-2 (4.8%) RMS error in the estimation of the mass acceleration. A damping coefficient as high as 53 Ns m-1 is achievable with the fabricated prototype. This novel <span class="hlt">eddy</span> current damper is an oil-free, inexpensive damper that is applicable in various vibration isolation systems such as precision machinery, micro-mechanical suspension systems and structure vibration isolation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007DSRII..54..789W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007DSRII..54..789W"><span>The Leeuwin Current and its <span class="hlt">eddies</span>: An introductory overview</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Waite, A. M.; Thompson, P. A.; Pesant, S.; Feng, M.; Beckley, L. E.; Domingues, C. M.; Gaughan, D.; Hanson, C. E.; Holl, C. M.; Koslow, T.; Meuleners, M.; Montoya, J. P.; Moore, T.; Muhling, B. A.; Paterson, H.; Rennie, S.; Strzelecki, J.; Twomey, L.</p> <p>2007-04-01</p> <p>The Leeuwin Current (LC) is an anomalous poleward-flowing eastern boundary current that carries warm, low-salinity water southward along the coast of Western Australia. We present an introduction to a new body of work on the physical and biological dynamics of the LC and its <span class="hlt">eddies</span>, collected in this Special Issue of Deep-Sea Research II, including (1) several modelling efforts aimed at understanding LC dynamics and <span class="hlt">eddy</span> generation, (2) papers from regional surveys of primary productivity and nitrogen uptake patterns in the LC, and (3) the first detailed field investigations of the biological oceanography of LC mesoscale <span class="hlt">eddies</span>. Key results in papers collected here include insight into the source regions of the LC and the Leeuwin Undercurrent (LUC), the energetic interactions of the LC and LUC, and their roles in the generation of warm-core (WC) and cold-core (CC) <span class="hlt">eddies</span>, respectively. In near-shore waters, the dynamics of upwelling were found to control the spatio-temporal variability of primary production, and important latitudinal differences were found in the fraction of production driven by nitrate (the f-ratio). The ubiquitous deep chlorophyll maximum within LC was found to be a significant contributor to total water column production within the region. WC <span class="hlt">eddies</span> including a single large <span class="hlt">eddy</span> studied in 2000 contained relatively elevated chlorophyll a concentrations thought to originate at least in part from the continental shelf/shelf break region and to have been incorporated during <span class="hlt">eddy</span> formation. During the <span class="hlt">Eddies</span> 2003 voyage, a more detailed study comparing the WC and CC <span class="hlt">eddies</span> illuminated more mechanistic details of the unusual dynamics and ecology of the <span class="hlt">eddies</span>. Food web analysis suggested that the WC <span class="hlt">eddy</span> had an enhanced "classic" food web, with more concentrated mesozooplankton and larger diatom populations than in the CC <span class="hlt">eddy</span>. Finally, implications for fisheries management are addressed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.3793V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.3793V"><span>Toward finding a universally applicable parameterization of the β factor for Relaxed <span class="hlt">Eddy</span> Accumulation applications</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vogl, Teresa; Hrdina, Amy; Thomas, Christoph</p> <p>2016-04-01</p> <p>-dioxide, latent and sensible heat fluxes across the contrasting environments. First, the choice of an appropriate scalar to calculate β0 is discussed considering the sources and sinks of each scalar with an emphasis on the carbon dioxide flux, which shows strongly dissimilar dynamics between the Antarctic ecosystem and the grassland. Secondly, the impact of atmospheric stability on both β models is investigated. In a next step, we attempt to find a physically meaningful explanation for the overestimation of the REA scalar fluxes compared to those from EC for using βw. We do so by analyzing the probability density function (pdf) and its statistical moments for the vertical wind speed. We found its pdf to be non-Gaussian for the majority of cases, and detected a close to linear relationship of its kurtosis with βw. Finally, in an attempt to provide practical guidance for field measurements, we integrate our findings and propose an enhanced model parameterization, and evaluate the differences between our new model and a constant β. Ammann, C. and Meixner, F.X. (2002) Stability dependence of the relaxed <span class="hlt">eddy</span> accumulation coefficient for various scalar quantities. J. Geophys. Res. 107. ACL7.1-ACL7.9 doi:10.1029/2001JD000649 Businger, J.A., Oncley, S.P. (1990) Flux measurement with conditional sampling. J. Atmos. Ocean. Tech. 7:349-352. Desjardins, R. L. (1972) A study of carbon-dioxide and sensible heat fluxes using the <span class="hlt">eddy</span> <span class="hlt">correlation</span> <span class="hlt">technique</span>, Ph.D. dissertation, Cornell University, 189 pp. Desjardins, R.L. (1977) Description and evaluation of sensible heat flux detector. Boundary-Layer Meteorol. 11:147-154. Katul, G., Finkelstein, P. L., Clarke, J. F., and Ellestad, T. G. (1996) An Investigation of the Conditional Sampling Methods Used to Estimate Fluxes of Active, Reactive and Passive Scalars. J. Appl. Meteorol. 35: 1835-1845. Milne, R., Beverland, I. J., Hargreaves, K., and Moncrieff, J. B. (1999) Variation of the beta coefficient in the relaxed <span class="hlt">eddy</span> accumulation method</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMNG24A..01B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMNG24A..01B"><span>Dynamically Consistent Parameterization of Mesoscale <span class="hlt">Eddies</span> This work aims at parameterization of <span class="hlt">eddy</span> effects for use in non-<span class="hlt">eddy</span>-resolving ocean models and focuses on the effect of the stochastic part of the <span class="hlt">eddy</span> forcing that backscatters and induces eastward jet extension of the western boundary currents and its adjacent recirculation zones.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berloff, P. S.</p> <p>2016-12-01</p> <p>This work aims at developing a framework for dynamically consistent parameterization of mesoscale <span class="hlt">eddy</span> effects for use in non-<span class="hlt">eddy</span>-resolving ocean circulation models. The proposed <span class="hlt">eddy</span> parameterization framework is successfully tested on the classical, wind-driven double-gyre model, which is solved both with explicitly resolved vigorous <span class="hlt">eddy</span> field and in the non-<span class="hlt">eddy</span>-resolving configuration with the <span class="hlt">eddy</span> parameterization replacing the <span class="hlt">eddy</span> effects. The parameterization focuses on the effect of the stochastic part of the <span class="hlt">eddy</span> forcing that backscatters and induces eastward jet extension of the western boundary currents and its adjacent recirculation zones. The parameterization locally approximates transient <span class="hlt">eddy</span> flux divergence by spatially localized and temporally periodic forcing, referred to as the plunger, and focuses on the linear-dynamics flow solution induced by it. The nonlinear self-interaction of this solution, referred to as the footprint, characterizes and quantifies the induced <span class="hlt">eddy</span> forcing exerted on the large-scale flow. We find that spatial pattern and amplitude of each footprint strongly depend on the underlying large-scale flow, and the corresponding relationships provide the basis for the <span class="hlt">eddy</span> parameterization and its closure on the large-scale flow properties. Dependencies of the footprints on other important parameters of the problem are also systematically analyzed. The parameterization utilizes the local large-scale flow information, constructs and scales the corresponding footprints, and then sums them up over the gyres to produce the resulting <span class="hlt">eddy</span> forcing field, which is interactively added to the model as an extra forcing. Thus, the assumed ensemble of plunger solutions can be viewed as a simple model for the cumulative effect of the stochastic <span class="hlt">eddy</span> forcing. The parameterization framework is implemented in the simplest way, but it provides a systematic strategy for improving the implementation algorithm.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.usgs.gov/wri/1996/4081/report.pdf','USGSPUBS'); return false;" href="https://pubs.usgs.gov/wri/1996/4081/report.pdf"><span>Comparison of Bowen-ratio, <span class="hlt">eddy-correlation</span>, and weighing-lysimeter evapotranspiration for two sparse-canopy sites in eastern Washington</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Tomlinson, S.A.</p> <p>1996-01-01</p> <p>This report compares evapotranspiration estimated with the Bowen-ratio and <span class="hlt">eddy-correlation</span> methods with evapotranspiration measured by weighing lysimeters for two sparse-canopy sites in eastern Washington. The sites are located in a grassland area (grass lysimeter site) and a sagbrush- covered area (sage lysimeter site) on the Arid Lands Ecology Reserve in Benton County, Washington. Lysimeter data were collected at the sites from August 1990 to November 1994. Bowen-ratio data were collected for varying periods from May 1993 to November 1994. Additional Bowen-ratio data without interchanging air- temperature and vapor-pressure sensors to remove sensor bias (fixed-sensor system) were collected from October 1993 to June 1994. <span class="hlt">Eddy-correlation</span> data were collected at the grass lysimeter site from March to April 1994, and at the sage lysimeter site from April to May 1994. The comparisons of evapotranspiration determined by the various methods differed considerably, depending on the periods of record being compared and the sites being analyzed. The year 1993 was very wet, with about 50 percent more precipitation than average; 1994 was a very dry year, with only about half the average precipitation. The study showed that on an annual basis, at least in 1994, Bowen-ratio evapotranspiration closely matched lysimeter evapotranspiration. In 1993, Bowen-ratio and lysimeter evapotranspiration comparisons were variable. Evapotranspiration estimated with the Bowen-ratio method averaged 5 percent more than evapotranspiration measured by lysimeters at the grass lysimeter site from October 1993 to November 1994, and 3 percent less than lysimeters at the sage lysimeter site from November 1993 to October 1994. From March 24 to April 5, 1994, at the grass lysimeter site, the Bowen-ratio method estimated 11 percent less, the Bowen-ratio method utilizing the fixed sensor system about 7 percent more, and the <span class="hlt">eddy-correlation</span> method about 28 percent less evapotranspiration than the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26097744','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26097744"><span>A daily global mesoscale ocean <span class="hlt">eddy</span> dataset from satellite altimetry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Faghmous, James H; Frenger, Ivy; Yao, Yuanshun; Warmka, Robert; Lindell, Aron; Kumar, Vipin</p> <p>2015-01-01</p> <p>Mesoscale ocean <span class="hlt">eddies</span> are ubiquitous coherent rotating structures of water with radial scales on the order of 100 kilometers. <span class="hlt">Eddies</span> play a key role in the transport and mixing of momentum and tracers across the World Ocean. We present a global daily mesoscale ocean <span class="hlt">eddy</span> dataset that contains ~45 million mesoscale features and 3.3 million <span class="hlt">eddy</span> trajectories that persist at least two days as identified in the AVISO dataset over a period of 1993-2014. This dataset, along with the open-source <span class="hlt">eddy</span> identification software, extract <span class="hlt">eddies</span> with any parameters (minimum size, lifetime, etc.), to study global <span class="hlt">eddy</span> properties and dynamics, and to empirically estimate the impact <span class="hlt">eddies</span> have on mass or heat transport. Furthermore, our open-source software may be used to identify mesoscale features in model simulations and compare them to observed features. Finally, this dataset can be used to study the interaction between mesoscale ocean <span class="hlt">eddies</span> and other components of the Earth System.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4460914','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4460914"><span>A daily global mesoscale ocean <span class="hlt">eddy</span> dataset from satellite altimetry</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Faghmous, James H.; Frenger, Ivy; Yao, Yuanshun; Warmka, Robert; Lindell, Aron; Kumar, Vipin</p> <p>2015-01-01</p> <p>Mesoscale ocean <span class="hlt">eddies</span> are ubiquitous coherent rotating structures of water with radial scales on the order of 100 kilometers. <span class="hlt">Eddies</span> play a key role in the transport and mixing of momentum and tracers across the World Ocean. We present a global daily mesoscale ocean <span class="hlt">eddy</span> dataset that contains ~45 million mesoscale features and 3.3 million <span class="hlt">eddy</span> trajectories that persist at least two days as identified in the AVISO dataset over a period of 1993–2014. This dataset, along with the open-source <span class="hlt">eddy</span> identification software, extract <span class="hlt">eddies</span> with any parameters (minimum size, lifetime, etc.), to study global <span class="hlt">eddy</span> properties and dynamics, and to empirically estimate the impact <span class="hlt">eddies</span> have on mass or heat transport. Furthermore, our open-source software may be used to identify mesoscale features in model simulations and compare them to observed features. Finally, this dataset can be used to study the interaction between mesoscale ocean <span class="hlt">eddies</span> and other components of the Earth System. PMID:26097744</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20959261','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20959261"><span>An efficient 3-D <span class="hlt">eddy</span>-current solver using an independent impedance method for transcranial magnetic stimulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>De Geeter, Nele; Crevecoeur, Guillaume; Dupre, Luc</p> <p>2011-02-01</p> <p>In many important bioelectromagnetic problem settings, <span class="hlt">eddy</span>-current simulations are required. Examples are the reduction of <span class="hlt">eddy</span>-current artifacts in magnetic resonance imaging and <span class="hlt">techniques</span>, whereby the <span class="hlt">eddy</span> currents interact with the biological system, like the alteration of the neurophysiology due to transcranial magnetic stimulation (TMS). TMS has become an important tool for the diagnosis and treatment of neurological diseases and psychiatric disorders. A widely applied method for simulating the <span class="hlt">eddy</span> currents is the impedance method (IM). However, this method has to contend with an ill conditioned problem and consequently a long convergence time. When dealing with optimal design problems and sensitivity control, the convergence rate becomes even more crucial since the <span class="hlt">eddy</span>-current solver needs to be evaluated in an iterative loop. Therefore, we introduce an independent IM (IIM), which improves the conditionality and speeds up the numerical convergence. This paper shows how IIM is based on IM and what are the advantages. Moreover, the method is applied to the efficient simulation of TMS. The proposed IIM achieves superior convergence properties with high time efficiency, compared to the traditional IM and is therefore a useful tool for accurate and fast TMS simulations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.A12E..03R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.A12E..03R"><span>Anisotropic Mesoscale <span class="hlt">Eddy</span> Transport in Ocean General Circulation Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reckinger, S. J.; Fox-Kemper, B.; Bachman, S.; Bryan, F.; Dennis, J.; Danabasoglu, G.</p> <p>2014-12-01</p> <p>Modern climate models are limited to coarse-resolution representations of large-scale ocean circulation that rely on parameterizations for mesoscale <span class="hlt">eddies</span>. The effects of <span class="hlt">eddies</span> are typically introduced by relating subgrid <span class="hlt">eddy</span> fluxes to the resolved gradients of buoyancy or other tracers, where the proportionality is, in general, governed by an <span class="hlt">eddy</span> transport tensor. The symmetric part of the tensor, which represents the diffusive effects of mesoscale <span class="hlt">eddies</span>, is universally treated isotropically in general circulation models. Thus, only a single parameter, namely the <span class="hlt">eddy</span> diffusivity, is used at each spatial and temporal location to impart the influence of mesoscale <span class="hlt">eddies</span> on the resolved flow. However, the diffusive processes that the parameterization approximates, such as shear dispersion, potential vorticity barriers, oceanic turbulence, and instabilities, typically have strongly anisotropic characteristics. Generalizing the <span class="hlt">eddy</span> diffusivity tensor for anisotropy extends the number of parameters to three: a major diffusivity, a minor diffusivity, and the principal axis of alignment. The Community Earth System Model (CESM) with the anisotropic <span class="hlt">eddy</span> parameterization is used to test various choices for the newly introduced parameters, which are motivated by observations and the <span class="hlt">eddy</span> transport tensor diagnosed from high resolution simulations. Simply setting the ratio of major to minor diffusivities to a value of five globally, while aligning the major axis along the flow direction, improves biogeochemical tracer ventilation and reduces global temperature and salinity biases. These effects can be improved even further by parameterizing the anisotropic transport mechanisms in the ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910021668','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910021668"><span><span class="hlt">Correlative</span> visualization <span class="hlt">techniques</span> for multidimensional data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Treinish, Lloyd A.; Goettsche, Craig</p> <p>1989-01-01</p> <p>Critical to the understanding of data is the ability to provide pictorial or visual representation of those data, particularly in support of <span class="hlt">correlative</span> data analysis. Despite the advancement of visualization <span class="hlt">techniques</span> for scientific data over the last several years, there are still significant problems in bringing today's hardware and software technology into the hands of the typical scientist. For example, there are other computer science domains outside of computer graphics that are required to make visualization effective such as data management. Well-defined, flexible mechanisms for data access and management must be combined with rendering algorithms, data transformation, etc. to form a generic visualization pipeline. A generalized approach to data visualization is critical for the <span class="hlt">correlative</span> analysis of distinct, complex, multidimensional data sets in the space and Earth sciences. Different classes of data representation <span class="hlt">techniques</span> must be used within such a framework, which can range from simple, static two- and three-dimensional line plots to animation, surface rendering, and volumetric imaging. Static examples of actual data analyses will illustrate the importance of an effective pipeline in data visualization system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-PIA13155.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-PIA13155.html"><span>Birth of a Loop Current <span class="hlt">Eddy</span></span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2010-05-24</p> <p>The northern portion of the Gulf of Mexico Loop Current, shown in red, appears about to detach a large ring of current, creating a separate <span class="hlt">eddy</span>. An <span class="hlt">eddy</span> is a large, warm, clockwise-spinning vortex of water -- the ocean version of a cyclone.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B51D0423R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B51D0423R"><span>Chamber and <span class="hlt">eddy</span> covariance comparisons of alternate wetting and drying and continuous flood irrigation in mid-South rice</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reba, M. L.; Fong, B.; Adviento-Borbe, A.; Runkle, B.</p> <p>2016-12-01</p> <p>The subtropical humid mid-south region produces nearly 75% of US rice. Rice cultivation contributes higher amounts of GHG emissions (CO2, CH4, and N2O) due to flooded field conditions. Accurate measurements of gas fluxes are important to regional and global climate models. A comparison between <span class="hlt">eddy</span> covariance and static vented flux chamber measurement <span class="hlt">techniques</span> is presented. These measurements were collected in two NE Arkansas commercial rice fields in 2015 and 2016 production seasons under two irrigation treatments: Alternate Wetting and Drying (AWD) and continuous flood (CF) irrigation. AWD can reduce GHG emissions and water use compared to CF by introducing aerobic conditions that reduce methanogen activity and drained conditions decrease water loss due to seepage or evapotranspiration. N2O was measured only with vented chambers, while CO2 and CH4 were measured with both <span class="hlt">techniques</span>. In the vented flux chamber <span class="hlt">technique</span>, headspace gas sampling occurred at least once a week every 20 minutes for one hour of chamber closure. Gas Chromatograph equipped with ECD and FID were used to analyze gas concentrations. <span class="hlt">Eddy</span> covariance used high frequency measurements wind and concentration measurements to determine fluxes. Chamber measurements were found to be more sensitive during seedling and early vegetative growth while <span class="hlt">eddy</span> covariance was more sensitive after canopy closure during mid-vegetative to reproductive growth. Unlike <span class="hlt">eddy</span> covariance which measured net CO2 exchange, flux chamber method measured only CO2 ecosystem respiration because flux measurements occurred using an opaque chamber material.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS31C2033A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS31C2033A"><span>Estimates of Oceanic <span class="hlt">Eddy</span> Heat and Salt Transports from Satellite Altimetry and Argo Profile Data.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Amores Maimo, A. M.; Melnichenko, O.; Maximenko, N. A.</p> <p>2016-12-01</p> <p>Horizontal heat and salt fluxes by mesoscale <span class="hlt">eddies</span> are estimated in the near-global ocean (10°-60° N and 10°-60° S) by combining historical records of Argo temperature/salinity profiles and satellite sea level anomaly data in the framework of the <span class="hlt">eddy</span> tracking <span class="hlt">technique</span>. The <span class="hlt">eddy</span> fluxes are expectedly strong in the western boundary currents and in the Southern Ocean along the Antarctic Circumpolar Current (ACC). The fluxes are generally weak, but not negligible in gyre interiors. In the vertical, the <span class="hlt">eddy</span> heat and salt fluxes are surface-intensified and confined mainly to the upper 600m layer, but their distribution with depth is not homogeneous throughout the ocean. In the Kuroshio Extension (KE) region, for example, the heat flux is poleward everywhere in the surface layer above the thermocline, but oppositely signed relative to the jet's axis in a deeper layer between approximately 300-800 m, where the flux is poleward on the northern side of the jet and equatorward on its southern side. Relatively strong fluxes at depth are also observed in the ACC, particularly in the Indian sector, and in the subtropical North Atlantic at the level of the Mediterranean Water (MW) at around 1000 m depth. The latter exemplifies the role of <span class="hlt">eddies</span> in MW spreading. These and other features of the longitude-latitude-depth distributions of the <span class="hlt">eddy</span> heat and salt fluxes, constructed for the first time from observational data, are presented and discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3260222','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3260222"><span>Mesoscale <span class="hlt">Eddies</span> Are Oases for Higher Trophic Marine Life</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Godø, Olav R.; Samuelsen, Annette; Macaulay, Gavin J.; Patel, Ruben; Hjøllo, Solfrid Sætre; Horne, John; Kaartvedt, Stein; Johannessen, Johnny A.</p> <p>2012-01-01</p> <p>Mesoscale <span class="hlt">eddies</span> stimulate biological production in the ocean, but knowledge of energy transfers to higher trophic levels within <span class="hlt">eddies</span> remains fragmented and not quantified. Increasing the knowledge base is constrained by the inability of traditional sampling methods to adequately sample biological processes at the spatio-temporal scales at which they occur. By combining satellite and acoustic observations over spatial scales of 10 s of km horizontally and 100 s of m vertically, supported by hydrographical and biological sampling we show that anticyclonic <span class="hlt">eddies</span> shape distribution and density of marine life from the surface to bathyal depths. Fish feed along density structures of <span class="hlt">eddies</span>, demonstrating that <span class="hlt">eddies</span> catalyze energy transfer across trophic levels. <span class="hlt">Eddies</span> create attractive pelagic habitats, analogous to oases in the desert, for higher trophic level aquatic organisms through enhanced 3-D motion that accumulates and redistributes biomass, contributing to overall bioproduction in the ocean. Integrating multidisciplinary observation methodologies promoted a new understanding of biophysical interaction in mesoscale <span class="hlt">eddies</span>. Our findings emphasize the impact of <span class="hlt">eddies</span> on the patchiness of biomass in the sea and demonstrate that they provide rich feeding habitat for higher trophic marine life. PMID:22272294</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO24B2959C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO24B2959C"><span>Effect of mesoscale <span class="hlt">eddies</span> on the Taiwan Strait Current</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chang, Y. L.; Miyazawa, Y.; Guo, X.</p> <p>2016-02-01</p> <p>This study shows that mesoscale <span class="hlt">eddies</span> can alter the Taiwan Strait current. The 20-year data-assimilated Japan Coastal Ocean Predictability Experiment 2 (JCOPE2) reanalysis data are analyzed, and the results are confirmed with idealized experiments. The leading wind-forced seasonal cycle is excluded to focus on the effect of the <span class="hlt">eddy</span>. The warm <span class="hlt">eddy</span> southwest of Taiwan is shown to generate a northward flow, whereas the cold <span class="hlt">eddy</span> produces a southward current. The effect of the <span class="hlt">eddy</span> penetrates onto the shelf through the Joint Effect of Baroclinicity and Relief (JEBAR). The cross-isobath fluxes lead to shelfward convergence and divergence, setting up the modulation of the sea level slope. The resulting along-strait current anomaly eventually affects a wide area of the Taiwan Strait. The stronger <span class="hlt">eddy</span> leads to larger modification of the cross-shelf flows and sea level slope, producing a greater transport anomaly. The composite Sea-Viewing Wide Field-of-view Sensor chlorophyll-a (Chl-a) serves as an indicator to show the change in Chl-a concentration in the strait in response to the <span class="hlt">eddy</span>-induced current. During the warm <span class="hlt">eddy</span> period, the current carries the southern water of lower concentration northward, reducing Chl-a concentration in the strait. In contrast, Chl-a is enhanced because the cold <span class="hlt">eddy</span>-induced southward current carries the northern water of higher concentration southward into the strait.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730019429','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730019429"><span>The relationship between <span class="hlt">eddy</span>-transport and second-order closure models for stratified media and for vortices</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Donaldson, C. D.</p> <p>1973-01-01</p> <p>The question is considered of how complex a model should be used for the calculation of turbulent shear flows. At the present time there are models varying in complexity from very simple <span class="hlt">eddy</span>-transport models to models in which all the equations for the nonzero second-order <span class="hlt">correlations</span> are solved simultaneously with the equations for the mean variables. A discussion is presented of the relationship between these two models of turbulent shear flow. Two types of motion are discussed: first, turbulent shear flow in a stratified medium and, second, the motion in a turbulent line vortex. These two cases are instructive because in the first example <span class="hlt">eddy</span>-transport methods have proven reasonably effective, whereas in the second, they have led to erroneous conclusions. It is not generally appreciated that the simplest form of <span class="hlt">eddy</span>-transport theory can be derived from second-order closure models of turbulent flow by a suitably limiting process. This limiting process and the suitability of <span class="hlt">eddy</span>-transport modeling for stratified media and line vortices are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17371723','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17371723"><span>A quantitative comparison of two methods to correct <span class="hlt">eddy</span> current-induced distortions in DT-MRI.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Muñoz Maniega, Susana; Bastin, Mark E; Armitage, Paul A</p> <p>2007-04-01</p> <p><span class="hlt">Eddy</span> current-induced geometric distortions of single-shot, diffusion-weighted, echo-planar (DW-EP) images are a major confounding factor to the accurate determination of water diffusion parameters in diffusion tensor MRI (DT-MRI). Previously, it has been suggested that these geometric distortions can be removed from brain DW-EP images using affine transformations determined from phantom calibration experiments using iterative cross-<span class="hlt">correlation</span> (ICC). Since this approach was first described, a number of image-based registration methods have become available that can also correct <span class="hlt">eddy</span> current-induced distortions in DW-EP images. However, as yet no study has investigated whether separate <span class="hlt">eddy</span> current calibration or image-based registration provides the most accurate way of removing these artefacts from DT-MRI data. Here we compare how ICC phantom calibration and affine FLIRT (http://www.fmrib.ox.ac.uk), a popular image-based multi-modal registration method that can correct both <span class="hlt">eddy</span> current-induced distortions and bulk subject motion, perform when registering DW-EP images acquired with different slice thicknesses (2.8 and 5 mm) and b-values (1000 and 3000 s/mm(2)). With the use of consistency testing, it was found that ICC was a more robust algorithm for correcting <span class="hlt">eddy</span> current-induced distortions than affine FLIRT, especially at high b-value and small slice thickness. In addition, principal component analysis demonstrated that the combination of ICC phantom calibration (to remove <span class="hlt">eddy</span> current-induced distortions) with rigid body FLIRT (to remove bulk subject motion) provided a more accurate registration of DT-MRI data than that achieved by affine FLIRT.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900032957&hterms=eddy+current+manufacturer&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Deddy%2Bcurrent%2Bmanufacturer','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900032957&hterms=eddy+current+manufacturer&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Deddy%2Bcurrent%2Bmanufacturer"><span>Thin film <span class="hlt">eddy</span> current impulse deicer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, Samuel O.; Zieve, Peter B.</p> <p>1990-01-01</p> <p>Two new styles of electrical impulse deicers has been developed and tested in NASA's Icing Research Tunnel. With the <span class="hlt">Eddy</span> Current Repulsion Deicing Boot (EDB), a thin and flexible spiral coil is encapsulated between two thicknesses of elastomer. The coil, made by an industrial printed circuit board manufacturer, is bonded to the aluminum aircraft leading edge. A capacitor bank is discharged through the coil. Induced <span class="hlt">eddy</span> currents repel the coil from the aluminum aircraft structure and shed accumulated ice. A second configuration, the <span class="hlt">Eddy</span> Current Repulsion Deicing-Strip (EDS) uses an outer metal erosion strip fastened over the coil. Opposite flowing <span class="hlt">eddy</span> currents repel the strip and create the impulse deicing force. The outer strip serves as a surface for the collection and shedding of ice and does not require any structural properties. The EDS is suitable for composite aircraft structures. Both systems successfully dispelled over 95 percent of the accumulated ice from airfoils over the range of the FAA icing envelope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002APS..CCP.G3001M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002APS..CCP.G3001M"><span>Analysis of Massively Separated Flows of Aircraft Using Detached <span class="hlt">Eddy</span> Simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Morton, Scott</p> <p>2002-08-01</p> <p>An important class of turbulent flows of aerodynamic interest are those characterized by massive separation, e.g., the flow around an aircraft at high angle of attack. Numerical simulation is an important tool for analysis, though traditional models used in the solution of the Reynolds-averaged Navier-Stokes (RANS) equations appear unable to accurately account for the time-dependent and three-dimensional motions governing flows with massive separation. Large-<span class="hlt">eddy</span> simulation (LES) is able to resolve these unsteady three-dimensional motions, yet is cost prohibitive for high Reynolds number wall-bounded flows due to the need to resolve the small scale motions in the boundary layer. Spalart et. al. proposed a hybrid <span class="hlt">technique</span>, Detached-<span class="hlt">Eddy</span> Simulation (DES), which takes advantage of the often adequate performance of RANS turbulence models in the "thin," typically attached regions of the flow. In the separated regions of the flow the <span class="hlt">technique</span> becomes a Large <span class="hlt">Eddy</span> Simulation, directly resolving the time-dependent and unsteady features that dominate regions of massive separation. The current work applies DES to a 70 degree sweep delta wing at 27 degrees angle of attack, a geometrically simple yet challenging flowfield that exhibits the unsteady three-dimensional massively separated phenomena of vortex breakdown. After detailed examination of this basic flowfield, the method is demonstrated on three full aircraft of interest characterized by massive separation, the F-16 at 45 degrees angle of attack, the F-15 at 65 degree angle of attack (with comparison to flight test), and the C-130 in a parachute drop condition at near stall speed with cargo doors open.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUSMOS51B..07C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUSMOS51B..07C"><span>Prospects and <span class="hlt">Techniques</span> for <span class="hlt">Eddy</span>-Resolving Acoustic Tomography in the Eastern Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caruthers, J. W.; Nechaev, D.; Roman, D. A.; Sidorovskaia, N. A.; Ioup, G. E.; Ioup, J.; Yaremchuk, M.</p> <p>2007-05-01</p> <p>For several decades monitoring and modeling the dynamics and physical structure of the Gulf of Mexico have been major efforts undertaken by oceanographers of the United States and other American countries. There are very interesting physical oceanographic features in the Gulf, not the least of which are the Gulf Loop Current and the <span class="hlt">eddies</span> it spawns. Satellite sensing of IR and altimeter imagery has been a major input to modeling those features. Such efforts are very important to the economy and well being of much of the United States and Mexico, including fisheries, mineral economies, hurricane strengths and paths in the summer, and severe snow storms in the eastern US in the winter. A major shortcoming of the present monitoring of the Gulf is the lack of subsurface input to the dynamic models of the Gulf. Acoustic tomography is a viable means of providing that missing input. Several universities have come together to investigate the prospects for establishing a Gulf <span class="hlt">Eddy</span> Monitoring System (GEMS) for the deep eastern half of the Gulf using acoustic tomography. The group has conducted several acoustics experiments and propagation studies to determine the feasibility of long-range propagation in the eastern Gulf and the mitigation of adverse effects on marine mammal populations in that region under the Office of Naval Research project entitled the Littoral Acoustic Demonstration Center (LADC). The group has also convened an invited session for the 9th World Multiconference on Systemics, Cybernetics and Informatics (WMSCI 2005) Orlando, FL, July 2005. This paper discusses prospects for establishing the GEMS tomographic system, its technical characteristics, and its contributions to advancing the knowledge of the dynamics of the Gulf. This presentation will concentrate on the characteristics of a single-slice tomographic system, called GEMS Phase I, across the approaches to the DeSoto Canyon in the northeastern Gulf and its prospect for monitoring the movements of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFDH23003R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFDH23003R"><span>Anisotropic mesoscale <span class="hlt">eddy</span> transport in ocean general circulation models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reckinger, Scott; Fox-Kemper, Baylor; Bachman, Scott; Bryan, Frank; Dennis, John; Danabasoglu, Gokhan</p> <p>2014-11-01</p> <p>In modern climate models, the effects of oceanic mesoscale <span class="hlt">eddies</span> are introduced by relating subgrid <span class="hlt">eddy</span> fluxes to the resolved gradients of buoyancy or other tracers, where the proportionality is, in general, governed by an <span class="hlt">eddy</span> transport tensor. The symmetric part of the tensor, which represents the diffusive effects of mesoscale <span class="hlt">eddies</span>, is universally treated isotropically. However, the diffusive processes that the parameterization approximates, such as shear dispersion and potential vorticity barriers, typically have strongly anisotropic characteristics. Generalizing the <span class="hlt">eddy</span> diffusivity tensor for anisotropy extends the number of parameters from one to three: major diffusivity, minor diffusivity, and alignment. The Community Earth System Model (CESM) with the anisotropic <span class="hlt">eddy</span> parameterization is used to test various choices for the parameters, which are motivated by observations and the <span class="hlt">eddy</span> transport tensor diagnosed from high resolution simulations. Simply setting the ratio of major to minor diffusivities to a value of five globally, while aligning the major axis along the flow direction, improves biogeochemical tracer ventilation and reduces temperature and salinity biases. These effects can be improved by parameterizing the oceanic anisotropic transport mechanisms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AIPC.1096.1069K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AIPC.1096.1069K"><span><span class="hlt">Eddy</span> Current Assessment of Engineered Components Containing Nanofibers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ko, Ray T.; Hoppe, Wally; Pierce, Jenny</p> <p>2009-03-01</p> <p>The <span class="hlt">eddy</span> current approach has been used to assess engineered components containing nanofibers. Five specimens with different programmed defects were fabricated. A 4-point collinear probe was used to verify the electrical resistivity of each specimen. The liftoff component of the <span class="hlt">eddy</span> current signal was used to test two extreme cases with different nano contents. Additional <span class="hlt">eddy</span> current measurements were also used in detecting a missing nano layer simulating a manufacturing process error. The results of this assessment suggest that <span class="hlt">eddy</span> current liftoff measurement can be a useful tool in evaluating the electrical properties of materials containing nanofibers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27910585','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27910585"><span>The <span class="hlt">eddy</span> current probe array for Keda Torus eXperiment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Zichao; Li, Hong; Tu, Cui; Hu, Jintong; You, Wei; Luo, Bing; Tan, Mingsheng; Adil, Yolbarsop; Wu, Yanqi; Shen, Biao; Xiao, Bingjia; Zhang, Ping; Mao, Wenzhe; Wang, Hai; Wen, Xiaohui; Zhou, Haiyang; Xie, Jinlin; Lan, Tao; Liu, Adi; Ding, Weixing; Xiao, Chijin; Liu, Wandong</p> <p>2016-11-01</p> <p>In a reversed field pinch device, the conductive shell is placed as close as possible to the plasma so as to balance the plasma during discharge. Plasma instabilities such as the resistive wall mode and certain tearing modes, which restrain the plasma high parameter operation, respond closely with conditions in the wall, in essence the <span class="hlt">eddy</span> current present. Also, the effect of <span class="hlt">eddy</span> currents induced by the external coils cannot be ignored when active control is applied to control instabilities. One diagnostic tool, an <span class="hlt">eddy</span> current probe array, detects the <span class="hlt">eddy</span> current in the composite shell. Magnetic probes measuring differences between the inner and outer magnetic fields enable estimates of the amplitude and angle of these <span class="hlt">eddy</span> currents. Along with measurements of currents through the copper bolts connecting the poloidal shield copper shells, we can obtain the <span class="hlt">eddy</span> currents over the entire shell. Magnetic field and <span class="hlt">eddy</span> current resolutions approach 2 G and 6 A, respectively. Additionally, the vortex electric field can be obtained by <span class="hlt">eddy</span> current probes. As the conductivity of the composite shell is high, the <span class="hlt">eddy</span> current probe array is very sensitive to the electric field and has a resolution of 0.2 mV/cm. In a bench test experiment using a 1/4 vacuum vessel, measurements of the induced <span class="hlt">eddy</span> currents are compared with simulation results based on a 3D electromagnetic model. The preliminary data of the <span class="hlt">eddy</span> currents have been detected during discharges in a Keda Torus eXperiment device. The typical value of toroidal and poloidal <span class="hlt">eddy</span> currents across the magnetic probe coverage rectangular area could reach 3.0 kA and 1.3 kA, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED093611.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED093611.pdf"><span><span class="hlt">Eddy</span> Current, Magnetic Particle and Hardness Testing, Aviation Quality Control (Advanced): 9227.04.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Dade County Public Schools, Miami, FL.</p> <p></p> <p>This unit of instruction includes the principles of <span class="hlt">eddy</span> current, magnetic particle and hardness testing; standards used for analyzing test results; <span class="hlt">techniques</span> of operating equipment; interpretation of indications; advantages and limitations of these methods of testing; care and calibration of equipment; and safety and work precautions. Motion…</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1418523','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1418523"><span>Combining <span class="hlt">eddy</span>-covariance and chamber measurements to determine the methane budget from a small, heterogeneous urban floodplain wetland park</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Morin, T. H.; Bohrer, G.; Stefanik, K. C.</p> <p></p> <p>Methane (CH 4) emissions and carbon uptake in temperate freshwater wetlands act in opposing directions in the context of global radiative forcing. Large uncertainties exist for the rates of CH 4 emissions making it difficult to determine the extent that CH 4 emissions counteract the carbon sequestration of wetlands. Urban temperate wetlands are typically small and feature highly heterogeneous land cover, posing an additional challenge to determining their CH 4 budget. The data analysis approach we introduce here combines two different CH 4 flux measurement <span class="hlt">techniques</span> to overcome scale and heterogeneity problems and determine the overall CH 4 budget ofmore » a small, heterogeneous, urban wetland landscape. Temporally intermittent point measurements from non-steady-state chambers provided information about patch-level heterogeneity of fluxes, while continuous, high temporal resolution flux measurements using the <span class="hlt">eddy</span>-covariance (EC) <span class="hlt">technique</span> provided information about the temporal dynamics of the fluxes. Patch-level scaling parameterization was developed from the chamber data to scale <span class="hlt">eddy</span> covariance data to a ‘fixed-frame’, which corrects for variability in the spatial coverage of the <span class="hlt">eddy</span> covariance observation footprint at any single point in time. Finally, by combining two measurement <span class="hlt">techniques</span> at different scales, we addressed shortcomings of both <span class="hlt">techniques</span> with respect to heterogeneous wetland sites.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1418523-combining-eddy-covariance-chamber-measurements-determine-methane-budget-from-small-heterogeneous-urban-floodplain-wetland-park','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1418523-combining-eddy-covariance-chamber-measurements-determine-methane-budget-from-small-heterogeneous-urban-floodplain-wetland-park"><span>Combining <span class="hlt">eddy</span>-covariance and chamber measurements to determine the methane budget from a small, heterogeneous urban floodplain wetland park</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Morin, T. H.; Bohrer, G.; Stefanik, K. C.; ...</p> <p>2017-02-17</p> <p>Methane (CH 4) emissions and carbon uptake in temperate freshwater wetlands act in opposing directions in the context of global radiative forcing. Large uncertainties exist for the rates of CH 4 emissions making it difficult to determine the extent that CH 4 emissions counteract the carbon sequestration of wetlands. Urban temperate wetlands are typically small and feature highly heterogeneous land cover, posing an additional challenge to determining their CH 4 budget. The data analysis approach we introduce here combines two different CH 4 flux measurement <span class="hlt">techniques</span> to overcome scale and heterogeneity problems and determine the overall CH 4 budget ofmore » a small, heterogeneous, urban wetland landscape. Temporally intermittent point measurements from non-steady-state chambers provided information about patch-level heterogeneity of fluxes, while continuous, high temporal resolution flux measurements using the <span class="hlt">eddy</span>-covariance (EC) <span class="hlt">technique</span> provided information about the temporal dynamics of the fluxes. Patch-level scaling parameterization was developed from the chamber data to scale <span class="hlt">eddy</span> covariance data to a ‘fixed-frame’, which corrects for variability in the spatial coverage of the <span class="hlt">eddy</span> covariance observation footprint at any single point in time. Finally, by combining two measurement <span class="hlt">techniques</span> at different scales, we addressed shortcomings of both <span class="hlt">techniques</span> with respect to heterogeneous wetland sites.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018WiEn...21..474L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018WiEn...21..474L"><span>Modeling space-time <span class="hlt">correlations</span> of velocity fluctuations in wind farms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lukassen, Laura J.; Stevens, Richard J. A. M.; Meneveau, Charles; Wilczek, Michael</p> <p>2018-07-01</p> <p>An analytical model for the streamwise velocity space-time <span class="hlt">correlations</span> in turbulent flows is derived and applied to the special case of velocity fluctuations in large wind farms. The model is based on the Kraichnan-Tennekes random sweeping hypothesis, capturing the decorrelation in time while including a mean wind velocity in the streamwise direction. In the resulting model, the streamwise velocity space-time <span class="hlt">correlation</span> is expressed as a convolution of the pure space <span class="hlt">correlation</span> with an analytical temporal decorrelation kernel. Hence, the spatio-temporal structure of velocity fluctuations in wind farms can be derived from the spatial <span class="hlt">correlations</span> only. We then explore the applicability of the model to predict spatio-temporal <span class="hlt">correlations</span> in turbulent flows in wind farms. Comparisons of the model with data from a large <span class="hlt">eddy</span> simulation of flow in a large, spatially periodic wind farm are performed, where needed model parameters such as spatial and temporal integral scales and spatial <span class="hlt">correlations</span> are determined from the large <span class="hlt">eddy</span> simulation. Good agreement is obtained between the model and large <span class="hlt">eddy</span> simulation data showing that spatial data may be used to model the full temporal structure of fluctuations in wind farms.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016OcSci..12.1249L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016OcSci..12.1249L"><span>GEM: a dynamic tracking model for mesoscale <span class="hlt">eddies</span> in the ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Qiu-Yang; Sun, Liang; Lin, Sheng-Fu</p> <p>2016-12-01</p> <p>The Genealogical Evolution Model (GEM) presented here is an efficient logical model used to track dynamic evolution of mesoscale <span class="hlt">eddies</span> in the ocean. It can distinguish between different dynamic processes (e.g., merging and splitting) within a dynamic evolution pattern, which is difficult to accomplish using other tracking methods. To this end, the GEM first uses a two-dimensional (2-D) similarity vector (i.e., a pair of ratios of overlap area between two <span class="hlt">eddies</span> to the area of each <span class="hlt">eddy</span>) rather than a scalar to measure the similarity between <span class="hlt">eddies</span>, which effectively solves the "missing <span class="hlt">eddy</span>" problem (temporarily lost <span class="hlt">eddy</span> in tracking). Second, for tracking when an <span class="hlt">eddy</span> splits, the GEM uses both "parent" (the original <span class="hlt">eddy</span>) and "child" (<span class="hlt">eddy</span> split from parent) and the dynamic processes are described as the birth and death of different generations. Additionally, a new look-ahead approach with selection rules effectively simplifies computation and recording. All of the computational steps are linear and do not include iteration. Given the pixel number of the target region L, the maximum number of <span class="hlt">eddies</span> M, the number N of look-ahead time steps, and the total number of time steps T, the total computer time is O(LM(N + 1)T). The tracking of each <span class="hlt">eddy</span> is very smooth because we require that the snapshots of each <span class="hlt">eddy</span> on adjacent days overlap one another. Although <span class="hlt">eddy</span> splitting or merging is ubiquitous in the ocean, they have different geographic distributions in the North Pacific Ocean. Both the merging and splitting rates of the <span class="hlt">eddies</span> are high, especially at the western boundary, in currents and in "<span class="hlt">eddy</span> deserts". The GEM is useful not only for satellite-based observational data, but also for numerical simulation outputs. It is potentially useful for studying dynamic processes in other related fields, e.g., the dynamics of cyclones in meteorology.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70194854','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70194854"><span>Transient <span class="hlt">eddy</span> formation around headlands</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Signell, Richard P.; Geyer, W. Rockwell</p> <p>1991-01-01</p> <p><span class="hlt">Eddies</span> with length scales of 1-10 km are commonly observed in coastal waters and play an important role in the dispersion of water-borne materials. The generation and evolution of these <span class="hlt">eddies</span> by oscillatory tidal flow around coastal headlands is investigated with analytical and numerical models. Using shallow water depth-averaged vorticity dynamics, <span class="hlt">eddies</span> are shown to form when flow separation occurs near the tip of the headland, causing intense vorticity generated along the headland to be injected into the interior. An analytic boundary layer model demonstrates that flow separation occurs when the pressure gradient along the boundary switches from favoring (accelerating) to adverse (decelerating), and its occurrence depends principally on three parameters: the aspect ratio [b/a], where b and a are characteristic width and length scales of the headland; [H/CDa], where H is the water depth, CD is the depth-averaged drag coefficient; and [Uo/aa], where Uo and a are the magnitude and frequency of the far-field tidal flow. Simulations with a depth-averaged numerical model show a wide range of responses to changes in these parameters, including cases where no separation occurs, cases where only one <span class="hlt">eddy</span> exists at a given time, and cases where bottom friction is weak enough that <span class="hlt">eddies</span> produced during successive tidal cycles coexist, interacting strongly with each other. These simulations also demonstrate that in unsteady flow, a strong start-up vortex forms after the flow separates, leading to a much more intense patch of vorticity and stronger recirculation than found in steady flow. </p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT........59F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT........59F"><span>Southern Ocean <span class="hlt">Eddy</span> Heat Flux and <span class="hlt">Eddy</span>-Mean Flow Interactions in Drake Passage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Foppert, Annie</p> <p></p> <p>The Antarctic Circumpolar Current (ACC) is a complex current system composed of multiple jets that is both unique to the world's oceans and relatively under observed compared with other current systems. Observations taken by current- and pressure-recording inverted echo sounders (CPIES) over four years, from November 2007 to November 2011, quantify the mean structure of one of the main jets of the ACC - the Polar Front - in a composite-mean sense. While the array of CPIES deployed in Drake Passage included a 3 x 7 local dynamics array, analysis of the Polar Front makes use of the line of CPIES that spanned the width of Drake Passage (C-Line). The Polar Front tends to prefer one of two locations, separated along the C-Line by 1° of latitude, with the core of the jet centered on corresponding geopotential height contours (with a 17 cm dierence between the northern and southern jets). Potential vorticity fields suggest that the Polar Front is susceptible to baroclinic instability, regardless of whether it is found upstream (farther south along the C-Line) or downstream (farther north along the C-Line) of the Shackleton Fracture Zone (SFZ), yet the core of the jet remains a barrier to smaller-scale mixing, as inferred from estimated mixing lengths. Within the local dynamics array of CPIES, the observed offset between <span class="hlt">eddy</span> heat flux (EHF) and <span class="hlt">eddy</span> kinetic energy (EKE) and the alignment of EHF with sea surface height (SSH) standard deviation motivates a proxy for depth-integrated EHF that can be estimated from available satellite SSH data. An <span class="hlt">eddy</span>-resolving numerical model develops the statistics of a logarithmic fit between SSH standard deviation and cross-frontal EHF that is applied to the ACC in a circumglobal sense. We find 1.06 PW enters the ACC from the north and 0.02 PW exits towards Antarctica. The magnitude of the estimated EHF, along with contemporaneous estimates of the mean heat flux, suggests that the air-sea heat flux south of the PF is an overestimate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMOS33B1456D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMOS33B1456D"><span>Increasing of <span class="hlt">eddy</span> activity in the northeastern Pacific during 1993-2011</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ding, M.; Lin, P.; Liu, H.; Chai, F.</p> <p>2017-12-01</p> <p>We study the long-term behaviors of <span class="hlt">eddy</span> activity in the northeastern Pacific (NEP) and the dynamic mechanism behind them based on the 3rd version of the mesoscale <span class="hlt">eddy</span> trajectories dataset released by Chelton et al. (2013) combined with other observation and reanalysis datasets. Both the <span class="hlt">eddy</span> kinetic energy (EKE) and <span class="hlt">eddy</span> occurrence number (EON) present prominent increasing trends, with inter-annual and decadal variabilities northeast of the Hawaii-Emperor seamounts. The increasing trend of the EON is mainly due to prolongation of the <span class="hlt">eddy</span> lifetime associated with the <span class="hlt">eddy</span> intensification, particularly for anticyclonic <span class="hlt">eddies</span> (AEs). Weakened surface winds tend to prolong the <span class="hlt">eddy</span> lifetimes, as the <span class="hlt">eddy</span> attenuation time scale is inversely proportional to the wind speed. The enhanced anticyclonic wind stress curl (WSC) anomalies inject more energy into the AE over the study region and provide a more suitable environment for AEs growth. The decadal climate modes, such as the Pacific decadal oscillation (PDO) and the North Pacific gyre oscillation (NPGO), may also modulate <span class="hlt">eddy</span> activities in the NEP by exerting fluctuations in the surface wind system.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.3329M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.3329M"><span>Subregional characterization of mesoscale <span class="hlt">eddies</span> across the Brazil-Malvinas Confluence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mason, Evan; Pascual, Ananda; Gaube, Peter; Ruiz, Simón; Pelegrí, Josep L.; Delepoulle, Antoine</p> <p>2017-04-01</p> <p>Horizontal and vertical motions associated with coherent mesoscale structures, including <span class="hlt">eddies</span> and meanders, are responsible for significant global transports of many properties, including heat and mass. Mesoscale vertical fluxes also influence upper ocean biological productivity by mediating the supply of nutrients into the euphotic layer, with potential impacts on the global carbon cycle. The Brazil-Malvinas Confluence (BMC) is a western boundary current region in the South Atlantic with intense mesoscale activity. This region has an active role in the genesis and transformation of water masses and thus is a critical component of the Atlantic meridional overturning circulation. The collision between the Malvinas and Brazil Currents over the Patagonian shelf/slope creates an energetic front that translates offshore to form a vigorous <span class="hlt">eddy</span> field. Recent improvements in gridded altimetric sea level anomaly fields allow us to track BMC mesoscale <span class="hlt">eddies</span> with high spatial and temporal resolutions using an automated <span class="hlt">eddy</span> tracker. We characterize the <span class="hlt">eddies</span> across fourteen 5° × 5° subregions. <span class="hlt">Eddy</span>-centric composites of tracers and geostrophic currents diagnosed from a global reanalysis of surface and in situ data reveal substantial subregional heterogeneity. The in situ data are also used to compute the evolving quasi-geostrophic vertical velocity (QG-ω) associated with each instantaneous <span class="hlt">eddy</span> instance. The QG-ω <span class="hlt">eddy</span> composites have the expected dipole patterns of alternating upwelling/downwelling, however, the magnitude and sign of azimuthally averaged vertical velocity varies among subregions. Maximum <span class="hlt">eddy</span> values are found near fronts and sharp topographic gradients. In comparison with regional <span class="hlt">eddy</span> composites, subregional composites provide refined information about mesoscale <span class="hlt">eddy</span> heterogeneity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhRvF...2k3801G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhRvF...2k3801G"><span>Simulations of <span class="hlt">eddy</span> kinetic energy transport in barotropic turbulence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grooms, Ian</p> <p>2017-11-01</p> <p><span class="hlt">Eddy</span> energy transport in rotating two-dimensional turbulence is investigated using numerical simulation. Stochastic forcing is used to generate an inhomogeneous field of turbulence and the time-mean energy profile is diagnosed. An advective-diffusive model for the transport is fit to the simulation data by requiring the model to accurately predict the observed time-mean energy distribution. Isotropic harmonic diffusion of energy is found to be an accurate model in the case of uniform, solid-body background rotation (the f plane), with a diffusivity that scales reasonably well with a mixing-length law κ ∝V ℓ , where V and ℓ are characteristic <span class="hlt">eddy</span> velocity and length scales. Passive tracer dynamics are added and it is found that the energy diffusivity is 75 % of the tracer diffusivity. The addition of a differential background rotation with constant vorticity gradient β leads to significant changes to the energy transport. The <span class="hlt">eddies</span> generate and interact with a mean flow that advects the <span class="hlt">eddy</span> energy. Mean advection plus anisotropic diffusion (with reduced diffusivity in the direction of the background vorticity gradient) is moderately accurate for flows with scale separation between the <span class="hlt">eddies</span> and mean flow, but anisotropic diffusion becomes a much less accurate model of the transport when scale separation breaks down. Finally, it is observed that the time-mean <span class="hlt">eddy</span> energy does not look like the actual <span class="hlt">eddy</span> energy distribution at any instant of time. In the future, stochastic models of the <span class="hlt">eddy</span> energy transport may prove more useful than models of the mean transport for predicting realistic <span class="hlt">eddy</span> energy distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24908640','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24908640"><span>Coupled circuit numerical analysis of <span class="hlt">eddy</span> currents in an open MRI system.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Akram, Md Shahadat Hossain; Terada, Yasuhiko; Keiichiro, Ishi; Kose, Katsumi</p> <p>2014-08-01</p> <p>We performed a new coupled circuit numerical simulation of <span class="hlt">eddy</span> currents in an open compact magnetic resonance imaging (MRI) system. Following the coupled circuit approach, the conducting structures were divided into subdomains along the length (or width) and the thickness, and by implementing coupled circuit concepts we have simulated transient responses of <span class="hlt">eddy</span> currents for subdomains in different locations. We implemented the Eigen matrix <span class="hlt">technique</span> to solve the network of coupled differential equations to speed up our simulation program. On the other hand, to compute the coupling relations between the biplanar gradient coil and any other conducting structure, we implemented the solid angle form of Ampere's law. We have also calculated the solid angle for three dimensions to compute inductive couplings in any subdomain of the conducting structures. Details of the temporal and spatial distribution of the <span class="hlt">eddy</span> currents were then implemented in the secondary magnetic field calculation by the Biot-Savart law. In a desktop computer (Programming platform: Wolfram Mathematica 8.0®, Processor: Intel(R) Core(TM)2 Duo E7500 @ 2.93GHz; OS: Windows 7 Professional; Memory (RAM): 4.00GB), it took less than 3min to simulate the entire calculation of <span class="hlt">eddy</span> currents and fields, and approximately 6min for X-gradient coil. The results are given in the time-space domain for both the direct and the cross-terms of the <span class="hlt">eddy</span> current magnetic fields generated by the Z-gradient coil. We have also conducted free induction decay (FID) experiments of <span class="hlt">eddy</span> fields using a nuclear magnetic resonance (NMR) probe to verify our simulation results. The simulation results were found to be in good agreement with the experimental results. In this study we have also conducted simulations for transient and spatial responses of secondary magnetic field induced by X-gradient coil. Our approach is fast and has much less computational complexity than the conventional electromagnetic numerical simulation</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840000104&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DEddy%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840000104&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DEddy%2Bcurrent"><span><span class="hlt">Eddy</span>-Current Inspection of Ball Bearings</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bankston, B.</p> <p>1985-01-01</p> <p>Custom <span class="hlt">eddy</span>-current probe locates surface anomalies. Low friction air cushion within cone allows ball to roll easily. <span class="hlt">Eddy</span> current probe reliably detects surface and near-surface cracks, voids, and material anomalies in bearing balls or other spherical objects. Defects in ball surface detected by probe displayed on CRT and recorded on strip-chart recorder.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014APS..DFDH27003H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014APS..DFDH27003H"><span>The turbulent cascade of individual <span class="hlt">eddies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huertas-Cerdeira, Cecilia; Lozano-Durán, Adrián; Jiménez, Javier</p> <p>2014-11-01</p> <p>The merging and splitting processes of Reynolds-stress carrying structures in the inertial range of scales are studied through their time-resolved evolution in channels at Reλ = 100 - 200 . Mergers and splits coexist during the whole life of the structures, and are responsible for a substantial part of their growth and decay. Each interaction involves two or more <span class="hlt">eddies</span> and results in little overall volume loss or gain. Most of them involve a small <span class="hlt">eddy</span> that merges with, or splits from, a significantly larger one. Accordingly, if merge and split indexes are respectively defined as the maximum number of times that a structure has merged from its birth or will split until its death, the mean <span class="hlt">eddy</span> volume grows linearly with both indexes, suggesting an accretion process rather than a hierarchical fragmentation. However, a non-negligible number of interactions involve <span class="hlt">eddies</span> of similar scale, with a second probability peak of the volume of the smaller parent or child at 0.3 times that of the resulting or preceding structure. Funded by the Multiflow project of the ERC.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRC..120..677E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRC..120..677E"><span>Cyclonic entrainment of preconditioned shelf waters into a frontal <span class="hlt">eddy</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Everett, J. D.; Macdonald, H.; Baird, M. E.; Humphries, J.; Roughan, M.; Suthers, I. M.</p> <p>2015-02-01</p> <p>The volume transport of nutrient-rich continental shelf water into a cyclonic frontal <span class="hlt">eddy</span> (entrainment) was examined from satellite observations, a Slocum glider and numerical simulation outputs. Within the frontal <span class="hlt">eddy</span>, parcels of water with temperature/salinity signatures of the continental shelf (18-19°C and >35.5, respectively) were recorded. The distribution of patches of shelf water observed within the <span class="hlt">eddy</span> was consistent with the spiral pattern shown within the numerical simulations. A numerical dye tracer experiment showed that the surface waters (≤50 m depth) of the frontal <span class="hlt">eddy</span> are almost entirely (≥95%) shelf waters. Particle tracking experiments showed that water was drawn into the <span class="hlt">eddy</span> from over 4° of latitude (30-34.5°S). Consistent with the glider observations, the modeled particles entrained into the <span class="hlt">eddy</span> sunk relative to their initial position. Particles released south of 33°S, where the waters are cooler and denser, sunk 34 m deeper than their release position. Distance to the shelf was a critical factor in determining the volume of shelf water entrained into the <span class="hlt">eddy</span>. Entrainment reduced to 0.23 Sv when the <span class="hlt">eddy</span> was furthest from the shelf, compared to 0.61 Sv when the <span class="hlt">eddy</span> was within 10 km of the shelf. From a biological perspective, quantifying the entrainment of shelf water into frontal <span class="hlt">eddies</span> is important, as it is thought to play a significant role in providing an offshore nursery habitat for coastally spawned larval fish.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/945563','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/945563"><span>Nesting large-<span class="hlt">eddy</span> simulations within mesoscale simulations for wind energy applications</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Lundquist, J K; Mirocha, J D; Chow, F K</p> <p>2008-09-08</p> <p>With increasing demand for more accurate atmospheric simulations for wind turbine micrositing, for operational wind power forecasting, and for more reliable turbine design, simulations of atmospheric flow with resolution of tens of meters or higher are required. These time-dependent large-<span class="hlt">eddy</span> simulations (LES), which resolve individual atmospheric <span class="hlt">eddies</span> on length scales smaller than turbine blades and account for complex terrain, are possible with a range of commercial and open-source software, including the Weather Research and Forecasting (WRF) model. In addition to 'local' sources of turbulence within an LES domain, changing weather conditions outside the domain can also affect flow, suggesting thatmore » a mesoscale model provide boundary conditions to the large-<span class="hlt">eddy</span> simulations. Nesting a large-<span class="hlt">eddy</span> simulation within a mesoscale model requires nuanced representations of turbulence. Our group has improved the Weather and Research Forecasting model's (WRF) LES capability by implementing the Nonlinear Backscatter and Anisotropy (NBA) subfilter stress model following Kosovic (1997) and an explicit filtering and reconstruction <span class="hlt">technique</span> to compute the Resolvable Subfilter-Scale (RSFS) stresses (following Chow et al, 2005). We have also implemented an immersed boundary method (IBM) in WRF to accommodate complex terrain. These new models improve WRF's LES capabilities over complex terrain and in stable atmospheric conditions. We demonstrate approaches to nesting LES within a mesoscale simulation for farms of wind turbines in hilly regions. Results are sensitive to the nesting method, indicating that care must be taken to provide appropriate boundary conditions, and to allow adequate spin-up of turbulence in the LES domain.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1358277','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1358277"><span>Determining Confounding Sensitivities In <span class="hlt">Eddy</span> Current Thin Film Measurements</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gros, Ethan; Udpa, Lalita; Smith, James A.</p> <p></p> <p>Determining Confounding Sensitivities In <span class="hlt">Eddy</span> Current Thin Film Measurements Ethan Gros, Lalita Udpa, Electrical Engineering, Michigan State University, East Lansing MI 48824 James A. Smith, Experiment Analysis, Idaho National Laboratory, Idaho Falls ID 83415 <span class="hlt">Eddy</span> current (EC) <span class="hlt">techniques</span> are widely used in industry to measure the thickness of non-conductive films on a metal substrate. This is done using a system whereby a coil carrying a high-frequency alternating current is used to create an alternating magnetic field at the surface of the instrument's probe. When the probe is brought near a conductive surface, the alternating magnetic field will induce ECs inmore » the conductor. The substrate characteristics and the distance of the probe from the substrate (the coating thickness) affect the magnitude of the ECs. The induced currents load the probe coil affecting the terminal impedance of the coil. The measured probe impedance is related to the lift off between coil and conductor as well as conductivity of the test sample. For a known conductivity sample, the probe impedance can be converted into an equivalent film thickness value. The EC measurement can be confounded by a number of measurement parameters. It is the goal of this research to determine which physical properties of the measurement set-up and sample can adversely affect the thickness measurement. The <span class="hlt">eddy</span> current testing is performed using a commercially available, hand held <span class="hlt">eddy</span> current probe (ETA3.3H spring loaded <span class="hlt">eddy</span> probe running at 8 MHz) that comes with a stand to hold the probe. The stand holds the probe and adjusts the probe on the z-axis to help position the probe in the correct area as well as make precise measurements. The signal from the probe is sent to a hand held readout, where the results are recorded directly in terms of liftoff or film thickness. Understanding the effect of certain factors on the measurements of film thickness, will help to evaluate how accurate the ETA3.3H</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUFM.B33D1575B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUFM.B33D1575B"><span><span class="hlt">Eddy</span> Covariance Method: Overview of General Guidelines and Conventional Workflow</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burba, G. G.; Anderson, D. J.; Amen, J. L.</p> <p>2007-12-01</p> <p>Atmospheric flux measurements are widely used to estimate water, heat, carbon dioxide and trace gas exchange between the ecosystem and the atmosphere. The <span class="hlt">Eddy</span> Covariance method is one of the most direct, defensible ways to measure and calculate turbulent fluxes within the atmospheric boundary layer. However, the method is mathematically complex, and requires significant care to set up and process data. These reasons may be why the method is currently used predominantly by micrometeorologists. Modern instruments and software can potentially expand the use of this method beyond micrometeorology and prove valuable for plant physiology, hydrology, biology, ecology, entomology, and other non-micrometeorological areas of research. The main challenge of the method for a non-expert is the complexity of system design, implementation, and processing of the large volume of data. In the past several years, efforts of the flux networks (e.g., FluxNet, Ameriflux, CarboEurope, Fluxnet-Canada, Asiaflux, etc.) have led to noticeable progress in unification of the terminology and general standardization of processing steps. The methodology itself, however, is difficult to unify, because various experimental sites and different purposes of studies dictate different treatments, and site-, measurement- and purpose-specific approaches. Here we present an overview of theory and typical workflow of the <span class="hlt">Eddy</span> Covariance method in a format specifically designed to (i) familiarize a non-expert with general principles, requirements, applications, and processing steps of the conventional <span class="hlt">Eddy</span> Covariance <span class="hlt">technique</span>, (ii) to assist in further understanding the method through more advanced references such as textbooks, network guidelines and journal papers, (iii) to help technicians, students and new researchers in the field deployment of the <span class="hlt">Eddy</span> Covariance method, and (iv) to assist in its use beyond micrometeorology. The overview is based, to a large degree, on the frequently asked questions</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AIPC.1706i0001H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AIPC.1706i0001H"><span>Investigating electrical resonance in <span class="hlt">eddy</span>-current array probes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hughes, R.; Fan, Y.; Dixon, S.</p> <p>2016-02-01</p> <p>The sensitivity enhancing effects of <span class="hlt">eddy</span>-current testing at frequencies close to electrical resonance are explored. Var-ied <span class="hlt">techniques</span> exploiting the phenomenon, dubbed near electrical resonance signal enhancement (NERSE), were experimentally investigated to evaluate its potential exploitation for other interesting applications in aerospace materials, in particular its potential for boosting the sensitivity of standard ECT measurements. Methods for setting and controlling the typically unstable resonant frequencies of such systems are discussed. This research is funded by the EPSRC, via the Research Centre for Non-Destructive Evaluation RCNDE, and Rolls-Royce plc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19900059999&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DEddy%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19900059999&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DEddy%2Bcurrent"><span>Solving time-dependent two-dimensional <span class="hlt">eddy</span> current problems</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lee, Min Eig; Hariharan, S. I.; Ida, Nathan</p> <p>1990-01-01</p> <p>Transient <span class="hlt">eddy</span> current calculations are presented for an EM wave-scattering and field-penetrating case in which a two-dimensional transverse magnetic field is incident on a good (i.e., not perfect) and infinitely long conductor. The problem thus posed is of initial boundary-value interface type, where the boundary of the conductor constitutes the interface. A potential function is used for time-domain modeling of the situation, and finite difference-time domain <span class="hlt">techniques</span> are used to march the potential function explicitly in time. Attention is given to the case of LF radiation conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JCoPh.337..252D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JCoPh.337..252D"><span>Numerical dissipation vs. subgrid-scale modelling for large <span class="hlt">eddy</span> simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dairay, Thibault; Lamballais, Eric; Laizet, Sylvain; Vassilicos, John Christos</p> <p>2017-05-01</p> <p>This study presents an alternative way to perform large <span class="hlt">eddy</span> simulation based on a targeted numerical dissipation introduced by the discretization of the viscous term. It is shown that this regularisation <span class="hlt">technique</span> is equivalent to the use of spectral vanishing viscosity. The flexibility of the method ensures high-order accuracy while controlling the level and spectral features of this purely numerical viscosity. A Pao-like spectral closure based on physical arguments is used to scale this numerical viscosity a priori. It is shown that this way of approaching large <span class="hlt">eddy</span> simulation is more efficient and accurate than the use of the very popular Smagorinsky model in standard as well as in dynamic version. The main strength of being able to correctly calibrate numerical dissipation is the possibility to regularise the solution at the mesh scale. Thanks to this property, it is shown that the solution can be seen as numerically converged. Conversely, the two versions of the Smagorinsky model are found unable to ensure regularisation while showing a strong sensitivity to numerical errors. The originality of the present approach is that it can be viewed as implicit large <span class="hlt">eddy</span> simulation, in the sense that the numerical error is the source of artificial dissipation, but also as explicit subgrid-scale modelling, because of the equivalence with spectral viscosity prescribed on a physical basis.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012BoLMe.142..207I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012BoLMe.142..207I"><span>Large-<span class="hlt">Eddy</span> Simulation of Coherent Flow Structures within a Cubical Canopy</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Inagaki, Atsushi; Castillo, Marieta Cristina L.; Yamashita, Yoshimi; Kanda, Manabu; Takimoto, Hiroshi</p> <p>2012-02-01</p> <p>Instantaneous flow structures "within" a cubical canopy are investigated via large-<span class="hlt">eddy</span> simulation. The main topics of interest are, (1) large-scale coherent flow structures within a cubical canopy, (2) how the structures are coupled with the turbulent organized structures (TOS) above them, and (3) the classification and quantification of representative instantaneous flow patterns within a street canyon in relation to the coherent structures. We use a large numerical domain (2,560 m × 2,560 m × 1,710 m) with a fine spatial resolution (2.5 m), thereby simulating a complete daytime atmospheric boundary layer (ABL), as well as explicitly resolving a regular array of cubes (40 m in height) at the surface. A typical urban ABL is numerically modelled. In this situation, the constant heat supply from roof and floor surfaces sustains a convective mixed layer as a whole, but strong wind shear near the canopy top maintains the surface layer nearly neutral. The results reveal large coherent structures in both the velocity and temperature fields "within" the canopy layer. These structures are much larger than the cubes, and their shapes and locations are shown to be closely related to the TOS above them. We classify the instantaneous flow patterns in a cavity, specifically focusing on two characteristic flow patterns: flushing and cavity-<span class="hlt">eddy</span> events. Flushing indicates a strong upward motion, while a cavity <span class="hlt">eddy</span> is characterized by a dominant vortical motion within a single cavity. Flushing is clearly <span class="hlt">correlated</span> with the TOS above, occurring frequently beneath low-momentum streaks. The instantaneous momentum and heat transport within and above a cavity due to flushing and cavity-<span class="hlt">eddy</span> events are also quantified.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-eddies-in-the-southern-ocean_17078909501_o.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-eddies-in-the-southern-ocean_17078909501_o.html"><span><span class="hlt">Eddies</span> in the Southern Ocean</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2015-04-08</p> <p>The cloud cover over the Southern Ocean occasionally parts as it did on January 1, 2015 just west of the Drake Passage where the VIIRS instrument on the Suomi NPP satellite glimpsed the above collection of ocean-color delineated <span class="hlt">eddies</span> which have diameters ranging from a couple of kilometers to a couple of hundred kilometers. Recent studies indicate that <span class="hlt">eddy</span> activity has been increasing in the Southern Ocean with possible implications for climate change. Credit: NASA's OceanColor/Suomi NPP/VIIRS</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14.1102B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14.1102B"><span>Methane Emissions from Permafrost Regions using Low-Power <span class="hlt">Eddy</span> Covariance Stations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Burba, G.; Sturtevant, C.; Schreiber, P.; Peltola, O.; Zulueta, R.; Mammarella, I.; Haapanala, S.; Rinne, J.; Vesala, T.; McDermitt, D.; Oechel, W.</p> <p>2012-04-01</p> <p>Methane is an important greenhouse gas with a warming potential 23 times that of carbon dioxide over a 100-year cycle. The permafrost regions of the world store significant amounts of organic materials under anaerobic conditions, leading to large methane production and accumulation in the upper layers of bedrock, soil and ice. These regions are currently undergoing dramatic change in response to warming trends, and may become a significant potential source of global methane release under a warming climate over the coming decades and centuries. Presently, most measurements of methane fluxes in permafrost regions have been made with static chamber <span class="hlt">techniques</span>, and very few were done with the <span class="hlt">eddy</span> covariance approach using closed-path analyzers. Although chambers and closed-path analyzers have advantages, both <span class="hlt">techniques</span> have significant limitations, especially for permafrost research. Static chamber measurements are discrete in time and space, and particularly difficult to use over polygonal tundra with highly non-uniform micro-topography and active water layer. They also may not capture the dynamics of methane fluxes on varying time scales (hours to annual estimates). In addition, placement of the chamber may disturb the surface integrity causing a significant over-estimation of the measured flux. Closed-path gas analyzers for measuring methane <span class="hlt">eddy</span> fluxes employ advanced technologies such as TDLS (Tunable Diode Laser Spectroscopy), ICOS (Integrated Cavity Output Spectroscopy), WS-CRDS (wavelength scanned cavity ring-down spectroscopy), but require high flow rates at significantly reduced optical cell pressures to provide adequate response time and sharpen absorption features. Such methods, when used with the <span class="hlt">eddy</span> covariance <span class="hlt">technique</span>, require a vacuum pump and a total of 400-1500 Watts of grid power for the pump and analyzer system. The weight of such systems often exceeds 100-200 lbs, restricting practical applicability for remote or portable field studies. As a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011JMS....85....1H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011JMS....85....1H"><span>Cyclonic <span class="hlt">eddies</span> identified in the Cape Basin of the South Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hall, C.; Lutjeharms, J. R. E.</p> <p>2011-03-01</p> <p>Inter-ocean exchange south of Africa takes place largely through the movement of Agulhas Rings into the Cape Basin. Recent observations have shown that the highly energetic flow field in this basin consists of anti-cyclonic rings as well as cyclonic <span class="hlt">eddies</span>. Very little is known of the characteristics of the cyclonic <span class="hlt">eddies</span>. Using altimetric data, this study determines the location, frequency and seasonality of these cyclonic <span class="hlt">eddies</span> their size, trajectories, life spans and their association with Agulhas Rings. Cyclonic <span class="hlt">eddies</span> were seen to split, merge and link with other cyclonic <span class="hlt">eddies</span>, where splitting events created child cyclonic <span class="hlt">eddies</span>. The 105 parent and 157 child cyclonic <span class="hlt">eddies</span> identified over a decade show that on average 11 parent and 17 child cyclonic <span class="hlt">eddies</span> appear annually in AVISO merged absolute dynamic topography data along the continental slope. Thirty-two percent follow an overall west south-westward direction, with 27% going west north-westward. Average translocation speeds are 2.2 ± 0.1 km/day for parent and 3.0 ± 0.2 km/day for child cyclonic <span class="hlt">eddies</span>. Parent cyclonic <span class="hlt">eddy</span> lifespan averaged 250 ± 18 days; whereas child cyclonic <span class="hlt">eddies</span> survived for only 118 ± 11 days. A significant difference in lifespan for parent and child cyclonic <span class="hlt">eddies</span> identified in the north and south region of the study area was detected. Seventy-seven percent of the northern and 93% of the southern cyclonic <span class="hlt">eddies</span> were first detected directly adjacent to passing Agulhas Rings, suggesting a vital interaction between these mesoscale <span class="hlt">eddies</span> within the region. Topographical features appeared to affect the behaviour and lifespan of these deep cyclonic <span class="hlt">eddies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22556043','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22556043"><span>An optimized velocity selective arterial spin labeling module with reduced <span class="hlt">eddy</span> current sensitivity for improved perfusion quantification.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Meakin, James A; Jezzard, Peter</p> <p>2013-03-01</p> <p>Velocity-selective (VS) arterial spin labeling is a promising method for measuring perfusion in areas of slow or collateral flow by eliminating the bolus arrival delay associated with other spin labeling <span class="hlt">techniques</span>. However, B(0) and B(1) inhomogeneities and <span class="hlt">eddy</span> currents during the VS preparation hinder accurate quantification of perfusion with VS arterial spin labeling. In this study, it is demonstrated through simulations and experiments in healthy volunteers that <span class="hlt">eddy</span> currents cause erroneous tagging of static tissue. Consequently, mean gray matter perfusion is overestimated by up to a factor of 2, depending on the VS preparation used. A novel eight-segment B(1) insensitive rotation VS preparation is proposed to reduce <span class="hlt">eddy</span> current effects while maintaining the B(0) and B(1) insensitivity of previous preparations. Compared to two previous VS preparations, the eight-segment B(1) insensitive rotation is the most robust to <span class="hlt">eddy</span> currents and should improve the quality and reliability of VS arterial spin labeling measurements in future studies. Copyright © 2012 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1998PhDT........55C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1998PhDT........55C"><span>Theory and application of high temperature superconducting <span class="hlt">eddy</span> current probes for nondestructive evaluation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Claycomb, James Ronald</p> <p>1998-10-01</p> <p>Several High-T c Superconducting (HTS) <span class="hlt">eddy</span> current probes have been developed for applications in electromagnetic nondestructive evaluation (NDE) of conducting materials. The probes utilize high-T c SUperconducting Quantum Interference Device (SQUID) magnetometers to detect the fields produced by the perturbation of induced <span class="hlt">eddy</span> currents resulting from subsurface flaws. Localized HTS shields are incorporated to selectively screen out environmental electromagnetic interference and enable movement of the instrument in the Earth's magnetic field. High permeability magnetic shields are employed to focus flux into, and thereby increase the <span class="hlt">eddy</span> current density in the metallic test samples. NDE test results are presented, in which machined flaws in aluminum alloy are detected by probes of different design. A novel current injection <span class="hlt">technique</span> performing NDE of wires using SQUIDs is also discussed. The HTS and high permeability shields are designed based on analytical and numerical finite element method (FEM) calculations presented here. Superconducting and high permeability magnetic shields are modeled in uniform noise fields and in the presence of dipole fields characteristic of flaw signals. Several shield designs are characterized in terms of (1) their ability to screen out uniform background noise fields; (2) the resultant improvement in signal-to-noise ratio and (3) the extent to which dipole source fields are distorted. An analysis of <span class="hlt">eddy</span> current induction is then presented for low frequency SQUID NDE. Analytical expressions are developed for the induced <span class="hlt">eddy</span> currents and resulting magnetic fields produced by excitation sources above conducting plates of varying thickness. The expressions derived here are used to model the SQUID's response to material thinning. An analytical defect model is also developed, taking into account the attenuation of the defect field through the conducting material, as well as the current flow around the edges of the flaw. Time harmonic</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016APS..DFDR34001C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016APS..DFDR34001C"><span>Time tracking and interaction of energy-<span class="hlt">eddies</span> at different scales</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cardesa, Jose I.; Vela-Martin, Alberto; Jimenez, Javier</p> <p>2016-11-01</p> <p>We study the energy cascade through coherent structures obtained in time-resolved simulations of incompressible, statistically steady isotropic turbulence. The structures are defined as geometrically connected regions of the flow with high kinetic energy. We compute the latter by band-pass filtering the velocity field around a scale r. We analyse the dynamics of structures extracted with different r, which are a proxy for <span class="hlt">eddies</span> containing energy at those r. We find that the size of these "energy-<span class="hlt">eddies</span>" scales with r, while their lifetime scales with the local <span class="hlt">eddy</span>-turnover r 2 / 3ɛ - 1 / 3 , where ɛ is the energy dissipation averaged over all space and time. Furthermore, a statistical analysis over the lives of the <span class="hlt">eddies</span> shows a slight predominance of the splitting over the merging process. When we isolate the <span class="hlt">eddies</span> which do not interact with other <span class="hlt">eddies</span> of the same scale, we observe a parent-child dependence by which, on average, structures are born at scale r during the decaying part of the life of a structure at scale r' > r . The energy-<span class="hlt">eddy</span> at r' lives in the same region of space as that at r. Finally, we investigate how interactions between <span class="hlt">eddies</span> at the same scale are echoed across other scales. Funded by the ERC project Coturb.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880013705','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880013705"><span>Self similarity of two point <span class="hlt">correlations</span> in wall bounded turbulent flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hunt, J. C. R.; Moin, P.; Moser, R. D.; Spalart, P. R.</p> <p>1987-01-01</p> <p>The structure of turbulence at a height y from a wall is affected by the local mean shear at y, by the direct effect of the wall on the <span class="hlt">eddies</span>, and by the action of other <span class="hlt">eddies</span> close to or far from the wall. Some researchers believe that a single one of these mechanisms is dominant, while others believe that these effects have to be considered together. It is important to understand the relative importance of these effects in order to develop closure models, for example for the dissipation or for the Reynolds stress equation, and to understand the <span class="hlt">eddy</span> structure of cross <span class="hlt">correlation</span> functions and other measures. The specific objective was to examine the two point <span class="hlt">correlation</span>, R sub vv, of the normal velocity component v near the wall in a turbulent channel flow and in a turbulent boundary layer. The preliminary results show that even in the inhomogeneous turbulent boundary layer, the two-point <span class="hlt">correlation</span> function may have self similar forms. The results also show that the effects of shear and of blocking are equally important in the form of <span class="hlt">correlation</span> functions for spacing normal to the wall. But for spanwise spacing, it was found that the <span class="hlt">eddy</span> structure is quire different in these near flows. So any theory for turbulent structure must take both these effects into account.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013SenIm..14...81V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013SenIm..14...81V"><span><span class="hlt">Eddy</span> Current Sensing of Torque in Rotating Shafts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varonis, Orestes J.; Ida, Nathan</p> <p>2013-12-01</p> <p>The noncontact torque sensing in machine shafts is addressed based on the stress induced in a press-fitted magnetoelastic sleeve on the shaft and <span class="hlt">eddy</span> current sensing of the changes of electrical conductivity and magnetic permeability due to the presence of stress. The <span class="hlt">eddy</span> current probe uses dual drive, dual sensing coils whose purpose is increased sensitivity to torque and decreased sensitivity to variations in distance between probe and shaft (liftoff). A mechanism of keeping the distance constant is also employed. Both the probe and the magnetoelastic sleeve are evaluated for performance using a standard <span class="hlt">eddy</span> current instrument. An <span class="hlt">eddy</span> current instrument is also used to drive the coils and analyze the torque data. The method and sensor described are general and adaptable to a variety of applications. The sensor is suitable for static and rotating shafts, is independent of shaft diameter and operational over a large range of torques. The torque sensor uses a differential <span class="hlt">eddy</span> current measurement resulting in cancellation of common mode effects including temperature and vibrations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070020326','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070020326"><span><span class="hlt">Eddy</span> Current System for Material Inspection and Flaw Visualization</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bachnak, R.; King, S.; Maeger, W.; Nguyen, T.</p> <p>2007-01-01</p> <p><span class="hlt">Eddy</span> current methods have been successfully used in a variety of non-destructive evaluation applications including detection of cracks, measurements of material thickness, determining metal thinning due to corrosion, measurements of coating thickness, determining electrical conductivity, identification of materials, and detection of corrosion in heat exchanger tubes. This paper describes the development of an <span class="hlt">eddy</span> current prototype that combines positional and <span class="hlt">eddy</span>-current data to produce a C-scan of tested material. The preliminary system consists of an <span class="hlt">eddy</span> current probe, a position tracking mechanism, and basic data visualization capability. Initial test results of the prototype are presented in this paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMGC23D1092Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMGC23D1092Z"><span>Long-term Trends and Variability of <span class="hlt">Eddy</span> Activities in the South China Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, M.; von Storch, H.</p> <p>2017-12-01</p> <p>For constructing empirical downscaling models and projecting possible future states of <span class="hlt">eddy</span> activities in the South China Sea (SCS), long-term statistical characteristics of the SCS <span class="hlt">eddy</span> are needed. We use a daily global <span class="hlt">eddy</span>-resolving model product named STORM covering the period of 1950-2010. This simulation has employed the MPI-OM model with a mean horizontal resolution of 10km and been driven by the NCEP reanalysis-1 data set. An <span class="hlt">eddy</span> detection and tracking algorithm operating on the gridded sea surface height anomaly (SSHA) fields was developed. A set of parameters for the criteria in the SCS are determined through sensitivity tests. Our method detected more than 6000 <span class="hlt">eddy</span> tracks in the South China Sea. For all of them, <span class="hlt">eddy</span> diameters, track length, <span class="hlt">eddy</span> intensity, <span class="hlt">eddy</span> lifetime and <span class="hlt">eddy</span> frequency were determined. The long-term trends and variability of those properties also has been derived. Most of the <span class="hlt">eddies</span> propagate westward. Nearly 100 <span class="hlt">eddies</span> travel longer than 1000km, and over 800 <span class="hlt">eddies</span> have a lifespan of more than 2 months. Furthermore, for building the statistical empirical model, the relationship between the SCS <span class="hlt">eddy</span> statistics and the large-scale atmospheric and oceanic phenomena has been investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1637.1406H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1637.1406H"><span>Non destructive <span class="hlt">technique</span> for cracks detection by an <span class="hlt">eddy</span> current in differential mode for steel frames</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Harzalla, S.; Belgacem, F. Bin Muhammad; Chabaat, M.</p> <p>2014-12-01</p> <p>In this paper, a nondestructive <span class="hlt">technique</span> is used as a tool to control cracks and microcracks in materials. A simulation by a numerical approach such as the finite element method is employed to detect cracks and eventually; to study their propagation using a crucial parameter such as the stress intensity factor. This approach has been used in the aircraft industry to control cracks. Besides, it makes it possible to highlight the defects of parts while preserving the integrity of the controlled products. On the other side, it is proven that the reliability of the control of defects gives convincing results for the improvement of the quality and the safety of the material. <span class="hlt">Eddy</span> current testing (ECT) is a standard <span class="hlt">technique</span> in industry for the detection of surface breaking flaws in magnetic materials such as steels. In this context, simulation tools can be used to improve the understanding of experimental signals, optimize the design of sensors or evaluate the performance of ECT procedures. CEA-LIST has developed for many years semi-analytical models embedded into the simulation platform CIVA dedicated to non-destructive testing. The developments presented herein address the case of flaws located inside a planar and magnetic medium. Simulation results are obtained through the application of the Volume Integral Method (VIM). When considering the ECT of a single flaw, a system of two differential equations is derived from Maxwell equations. The numerical resolution of the system is carried out using the classical Galerkin variant of the Method of Moments. Besides, a probe response is calculated by application of the Lorentz reciprocity theorem. Finally, the approach itself as well as comparisons between simulation results and measured data are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010AGUFM.B11D0379L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010AGUFM.B11D0379L"><span>A Semi-parametric Multivariate Gap-filling Model for <span class="hlt">Eddy</span> Covariance Latent Heat Flux</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, M.; Chen, Y.</p> <p>2010-12-01</p> <p>Quantitative descriptions of latent heat fluxes are important to study the water and energy exchanges between terrestrial ecosystems and the atmosphere. The <span class="hlt">eddy</span> covariance approaches have been recognized as the most reliable <span class="hlt">technique</span> for measuring surface fluxes over time scales ranging from hours to years. However, unfavorable micrometeorological conditions, instrument failures, and applicable measurement limitations may cause inevitable flux gaps in time series data. Development and application of suitable gap-filling <span class="hlt">techniques</span> are crucial to estimate long term fluxes. In this study, a semi-parametric multivariate gap-filling model was developed to fill latent heat flux gaps for <span class="hlt">eddy</span> covariance measurements. Our approach combines the advantages of a multivariate statistical analysis (principal component analysis, PCA) and a nonlinear interpolation <span class="hlt">technique</span> (K-nearest-neighbors, KNN). The PCA method was first used to resolve the multicollinearity relationships among various hydrometeorological factors, such as radiation, soil moisture deficit, LAI, and wind speed. The KNN method was then applied as a nonlinear interpolation tool to estimate the flux gaps as the weighted sum latent heat fluxes with the K-nearest distances in the PCs’ domain. Two years, 2008 and 2009, of <span class="hlt">eddy</span> covariance and hydrometeorological data from a subtropical mixed evergreen forest (the Lien-Hua-Chih Site) were collected to calibrate and validate the proposed approach with artificial gaps after standard QC/QA procedures. The optimal K values and weighting factors were determined by the maximum likelihood test. The results of gap-filled latent heat fluxes conclude that developed model successful preserving energy balances of daily, monthly, and yearly time scales. Annual amounts of evapotranspiration from this study forest were 747 mm and 708 mm for 2008 and 2009, respectively. Nocturnal evapotranspiration was estimated with filled gaps and results are comparable with other studies</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1030928','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1030928"><span>Model based Inverse Methods for Sizing Cracks of Varying Shape and Location in Bolt hole <span class="hlt">Eddy</span> Current (BHEC) Inspections (Postprint)</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2016-02-10</p> <p>using bolt hole <span class="hlt">eddy</span> current (BHEC) <span class="hlt">techniques</span>. Data was acquired for a wide range of crack sizes and shapes, including mid- bore , corner and through...to select the most appropriate VIC-3D surrogate model for subsequent crack sizing inversion step. Inversion results for select mid- bore , through and...the flaw. 15. SUBJECT TERMS Bolt hole <span class="hlt">eddy</span> current (BHEC); mid- bore , corner and through-thickness crack types; VIC-3D generated surrogate models</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25571425','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25571425"><span>BRAIN initiative: fast and parallel solver for real-time monitoring of the <span class="hlt">eddy</span> current in the brain for TMS applications.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sabouni, Abas; Pouliot, Philippe; Shmuel, Amir; Lesage, Frederic</p> <p>2014-01-01</p> <p>This paper introduce a fast and efficient solver for simulating the induced (<span class="hlt">eddy</span>) current distribution in the brain during transcranial magnetic stimulation procedure. This solver has been integrated with MRI and neuronavigation software to accurately model the electromagnetic field and show <span class="hlt">eddy</span> current in the head almost in real-time. To examine the performance of the proposed <span class="hlt">technique</span>, we used a 3D anatomically accurate MRI model of the 25 year old female subject.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=septic+AND+tank&id=EJ106352','ERIC'); return false;" href="https://eric.ed.gov/?q=septic+AND+tank&id=EJ106352"><span><span class="hlt">Correlation</span> of Three <span class="hlt">Techniques</span> for Determining Soil Permeability</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Winneberger, John T.</p> <p>1974-01-01</p> <p>Discusses problems of acquiring adequate results when measuring for soil permeability. <span class="hlt">Correlates</span> three relatively simple <span class="hlt">techniques</span> that could be helpful to the inexperienced technician dealing with septic tank practices. An appendix includes procedures for valid percolation tests. (MLB)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMOS33B1458S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMOS33B1458S"><span>Convection anomalies associated with warm <span class="hlt">eddy</span> at the coastal area</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shi, R.; Wang, D.</p> <p>2017-12-01</p> <p>A possible <span class="hlt">correlation</span> between a warm <span class="hlt">eddy</span> and thunderstorms and convective precipitations are investigated at the coastal area in the northwestern South China Sea. Compared to the climatological mean in August from 2006 to 2013, an extreme enhancement of thunderstorm activities and precipitation rate are identified at the southern offshore area of Hainan island in August 2010 when a strong and long-live warm <span class="hlt">eddy</span> was observed near the coastline at the same time. The 3 hourly satellite data (TRMM) indicate that the nocturnal convections is strong offshore and that could be responsible for the extreme positive anomalies of thunderstorms and rainfall in August 2010. The TRMM data also show a small reduction of thunderstorm activities and rainfall on the island in the afternoon. Meanwhile, the Weather Research and Forecasting (WRF) model was applied to simulate the change of rainfall in August 2010. The WRF simulation of rainfall rate is comparable with the observation results while there is some difference in the spatial distribution. The WRF simulation successfully captured the strong offshore rainfall and the diurnal variation of rainfall in August 2010. The WRF simulation indicated that the different convergence induced by sea/land breeze could be one essential reason for the adjustment of thunderstorms and rainfall in 2010. The substantial connection between sea/land breeze and upper layer heat content modified by the warm <span class="hlt">eddy</span> is still on ongoing and will be reported in the future work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008DyAtO..45..252T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008DyAtO..45..252T"><span>Formation of intrathermocline <span class="hlt">eddies</span> at ocean fronts by wind-driven destruction of potential vorticity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomas, Leif N.</p> <p>2008-08-01</p> <p>A mechanism for the generation of intrathermocline <span class="hlt">eddies</span> (ITEs) at wind-forced fronts is examined using a high resolution numerical simulation. Favorable conditions for ITE formation result at fronts forced by "down-front" winds, i.e. winds blowing in the direction of the frontal jet. Down-front winds exert frictional forces that reduce the potential vorticity (PV) within the surface boundary in the frontal outcrop, providing a source for the low-PV water that is the materia prima of ITEs. Meandering of the front drives vertical motions that subduct the low-PV water into the pycnocline, pooling it into the coherent anticyclonic vortex of a submesoscale ITE. As the fluid is subducted along the outcropping frontal isopycnal, the low-PV water, which at the surface is associated with strongly baroclinic flow, re-expresses itself as water with nearly zero absolute vorticity. This generation of strong anticyclonic vorticity results from the tilting of the horizontal vorticity of the frontal jet, not from vortex squashing. During the formation of the ITE, high-PV water from the pycnocline is upwelled alongside the subducting low-PV surface water. The positive <span class="hlt">correlation</span> between the ITE's velocity and PV fields results in an upward, along-isopycnal <span class="hlt">eddy</span> PV flux that scales with the surface frictional PV flux driven by the wind. The relationship between the <span class="hlt">eddy</span> and wind-induced frictional PV flux is nonlocal in time, as the <span class="hlt">eddy</span> PV flux persists long after the wind forcing is shut off. The ITE's PV flux affects the large-scale flow by driving an <span class="hlt">eddy</span>-induced transport or bolus velocity down the outcropping isopycnal layer with a magnitude that scales with the Ekman velocity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFMOS41D..05S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFMOS41D..05S"><span>Recent Ship, Satellite and Autonomous Observations of Southern Ocean <span class="hlt">Eddies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Strutton, P. G.; Moreau, S.; Llort, J.; Phillips, H. E.; Patel, R.; Della Penna, A.; Langlais, C.; Lenton, A.; Matear, R.; Dawson, H.; Boyd, P. W.</p> <p>2016-12-01</p> <p>The Southern Ocean is the area of greatest uncertainty regarding the exchange of CO2 between the ocean and atmosphere. It is also a region of abundant energetic <span class="hlt">eddies</span> that significantly impact circulation and biogeochemistry. In the Indian sector of the Southern Ocean, cyclonic <span class="hlt">eddies</span> are unusual in that they are upwelling favorable, as for cyclonic <span class="hlt">eddies</span> elsewhere, but during summer they are low in silicate and phytoplankton biomass. The reverse is true for anticyclonic <span class="hlt">eddies</span> in that they have counter-intuitive positive chlorophyll anomalies in summer. Similar but less obvious patterns occur in the Pacific and Atlantic sectors. Using ship, satellite and autonomous observations in the region south of Australia, the physical and biogeochemical signatures of both types of <span class="hlt">eddies</span> were documented in 2016. A cyclonic <span class="hlt">eddy</span> that lived for seven weeks exhibited doming isopycnals indicative of upwelling. However, low surface silicate and chlorophyll concentrations appeared to be characteristic of surface waters to the south where the <span class="hlt">eddy</span> formed. Higher chlorophyll was confined to filaments at the <span class="hlt">eddy</span> edge. Surface nitrate and phosphate concentrations were more than sufficient for a bloom of non-siliceous phytoplankton to occur. Acoustic observations from a high resolution TRIAXUS transect through the <span class="hlt">eddy</span> documented high zooplankton biomass in the upper 150m. It is hypothesized that a non-diatom bloom was prevented by grazing pressure, but light may have also been an important limiting resource in late summer (April). Two SOCCOM floats that were deployed in the <span class="hlt">eddy</span> field continued to monitor the physics, nitrate and bio-optics through the transition to winter. These observations across complementary platforms have identified and then explained the reason for these unexpected biological anomalies in an energetic and globally important region of the global ocean. Understanding the role of <span class="hlt">eddies</span> in this region will be critical to the representation of mesoscale</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870050550&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DEddy%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870050550&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DEddy%2Bcurrent"><span>The influence of <span class="hlt">eddy</span> currents on magnetic actuator performance</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zmood, R. B.; Anand, D. K.; Kirk, J. A.</p> <p>1987-01-01</p> <p>The present investigation of the effects of <span class="hlt">eddy</span> currents on EM actuators' transient performance notes that a transfer function representation encompassing a first-order model of the <span class="hlt">eddy</span> current influence can be useful in control system analysis. The method can be extended to represent the higher-order effects of <span class="hlt">eddy</span> currents for actuators that cannot be represented by semiinfinite planes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008ACP.....8..555N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008ACP.....8..555N"><span><span class="hlt">Eddy</span> covariance measurements of sea spray particles over the Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Norris, S. J.; Brooks, I. M.; de Leeuw, G.; Smith, M. H.; Moerman, M.; Lingard, J. J. N.</p> <p>2008-02-01</p> <p>Most estimates of sea spray aerosol source functions have used indirect means to infer the rate of production as a function of wind speed. Only recently has the technology become available to make high frequency measurements of aerosol spectra suitable for direct <span class="hlt">eddy</span> <span class="hlt">correlation</span> determination of the sea spray particle flux. This was accomplished in this study by combining a newly developed fast aerosol particle counter with an ultrasonic anemometer which allowed for <span class="hlt">eddy</span> covariance measurements of size-segregated particle fluxes. The aerosol instrument is the Compact Lightweight Aerosol Spectrometer Probe (CLASP) - capable of measuring 8-channel size spectra for mean radii between 0.15 and 3.5 µm at 10 Hz. The first successful measurements were made during the Waves, Air Sea Fluxes, Aerosol and Bubbles (WASFAB) field campaign in October 2005 in Duck (NC, USA). The method and initial results are presented and comparisons are made with recent sea spray source functions from the literature.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <div id="page_14" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="261"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007ACPD....713243N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007ACPD....713243N"><span><span class="hlt">Eddy</span> covariance measurements of sea spray particles over the Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Norris, S.; Brooks, I.; de Leeuw, G.; Smith, M. H.; Moeman, M.; Lingard, J.</p> <p>2007-09-01</p> <p>Most estimates of sea spray aerosol source functions have used indirect means to infer the rate of production as a function of wind speed. Only recently has the technology become available to make high frequency measurements of aerosol concentration suitable for direct <span class="hlt">eddy</span> <span class="hlt">correlation</span> determination of the particle flux. This was accomplished in this study by combining a newly developed fast aerosol particle counter with an ultrasonic anemometer which allowed for <span class="hlt">eddy</span> covariance measurements of size-segregated particle fluxes. The aerosol instrument is the Compact Lightweight Aerosol Spectrometer Probe (CLASP) - capable of measuring 8-channel size spectra for mean radii between 0.15 and 0.35 μm at 10 Hz. The first successful measurements were made during the WASFAB (Waves, Air Sea Fluxes, Aerosol and Bubbles) field campaign in October 2005 in Duck (NC, USA). The method and results are presented and comparisons are made with recent sea spray source functions from the literature.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3875410','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3875410"><span>Carbon Dynamics within Cyclonic <span class="hlt">Eddies</span>: Insights from a Biomarker Study</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Alonso-González, Iván J.; Arístegui, Javier; Lee, Cindy; Sanchez-Vidal, Anna; Calafat, Antoni; Fabrés, Joan; Sangrá, Pablo; Mason, Evan</p> <p>2013-01-01</p> <p>It is generally assumed that episodic nutrient pulses by cyclonic <span class="hlt">eddies</span> into surface waters support a significant fraction of the primary production in subtropical low-nutrient environments in the northern hemisphere. However, contradictory results related to the influence of <span class="hlt">eddies</span> on particulate organic carbon (POC) export have been reported. As a step toward understanding the complex mechanisms that control export of material within <span class="hlt">eddies</span>, we present here results from a sediment trap mooring deployed within the path of cyclonic <span class="hlt">eddies</span> generated near the Canary Islands over a 1.5-year period. We find that, during summer and autumn (when surface stratification is stronger, <span class="hlt">eddies</span> are more intense, and a relative enrichment in CaCO3 forming organisms occurs), POC export to the deep ocean was 2–4 times higher than observed for the rest of the year. On the contrary, during winter and spring (when mixing is strongest and the seasonal phytoplankton bloom occurs), no significant enhancement of POC export associated with <span class="hlt">eddies</span> was observed. Our biomarker results suggest that a large fraction of the material exported from surface waters during the late-winter bloom is either recycled in the mesopelagic zone or bypassed by migrant zooplankton to the deep scattering layer, where it would disaggregate to smaller particles or be excreted as dissolved organic carbon. Cyclonic <span class="hlt">eddies</span>, however, would enhance carbon export below 1000 m depth during the summer stratification period, when <span class="hlt">eddies</span> are more intense and frequent, highlighting the important role of <span class="hlt">eddies</span> and their different biological communities on the regional carbon cycle. PMID:24386098</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/24386098','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/24386098"><span>Carbon dynamics within cyclonic <span class="hlt">eddies</span>: insights from a biomarker study.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Alonso-González, Iván J; Arístegui, Javier; Lee, Cindy; Sanchez-Vidal, Anna; Calafat, Antoni; Fabrés, Joan; Sangrá, Pablo; Mason, Evan</p> <p>2013-01-01</p> <p>It is generally assumed that episodic nutrient pulses by cyclonic <span class="hlt">eddies</span> into surface waters support a significant fraction of the primary production in subtropical low-nutrient environments in the northern hemisphere. However, contradictory results related to the influence of <span class="hlt">eddies</span> on particulate organic carbon (POC) export have been reported. As a step toward understanding the complex mechanisms that control export of material within <span class="hlt">eddies</span>, we present here results from a sediment trap mooring deployed within the path of cyclonic <span class="hlt">eddies</span> generated near the Canary Islands over a 1.5-year period. We find that, during summer and autumn (when surface stratification is stronger, <span class="hlt">eddies</span> are more intense, and a relative enrichment in CaCO3 forming organisms occurs), POC export to the deep ocean was 2-4 times higher than observed for the rest of the year. On the contrary, during winter and spring (when mixing is strongest and the seasonal phytoplankton bloom occurs), no significant enhancement of POC export associated with <span class="hlt">eddies</span> was observed. Our biomarker results suggest that a large fraction of the material exported from surface waters during the late-winter bloom is either recycled in the mesopelagic zone or bypassed by migrant zooplankton to the deep scattering layer, where it would disaggregate to smaller particles or be excreted as dissolved organic carbon. Cyclonic <span class="hlt">eddies</span>, however, would enhance carbon export below 1000 m depth during the summer stratification period, when <span class="hlt">eddies</span> are more intense and frequent, highlighting the important role of <span class="hlt">eddies</span> and their different biological communities on the regional carbon cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOS.B44B0379X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOS.B44B0379X"><span>Impacts of mesoscale <span class="hlt">eddies</span> on biogeochemical cycles in the South China Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiu, P.; Chai, F.; Guo, M.</p> <p>2016-02-01</p> <p>Biogeochemical cycles associated with mesoscale <span class="hlt">eddies</span> in the South China Sea (SCS) are investigated by using satellite surface chlorophyll concentration, altimeter data, satellite sea surface temperature, and a coupled physical-biogeochemical Pacific Ocean model (ROMS-CoSiNE) simulation for the period from 1991 to 2007. Considering the annual mean, composite analysis reveals that cyclonic <span class="hlt">eddies</span> are associated with higher concentrations of nutrients, phytoplankton and zooplankton while the anticyclonic <span class="hlt">eddies</span> are with lower concentrations compared with surrounding waters, which is generally controlled by the <span class="hlt">eddy</span> pumping mechanism. Dipole structures of vertical fluxes with net upward motion in cyclonic <span class="hlt">eddies</span> and net downward motion in anticyclonic <span class="hlt">eddies</span> are also revealed. During the lifetime of an <span class="hlt">eddy</span>, the evolutions of physical, biological, and chemical structures are not linearly coupled at the <span class="hlt">eddy</span> core where plankton grow and composition of the community depend not only on the physical and chemical processes but also on the adjustments by the predator-prey relationship. Considering the seasonal variability, we find <span class="hlt">eddy</span> pumping mechanisms are generally dominant in winter and <span class="hlt">eddy</span> advection effects are dominant in summer. Over the space, variability of chlorophyll to the west of Luzon Strait and off northwest of Luzon Island are mainly controlled by <span class="hlt">eddy</span> pumping mechanism. In regions off the Vietnam coast, chlorophyll distributions are generally associated with horizontal <span class="hlt">eddy</span> advection. This research highlights different mesoscale mechanisms affecting biological structures that can potentially disturb ocean biogeochemical cycling processes in the South China Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4732048','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4732048"><span>Corrosion Assessment of Steel Bars Used in Reinforced Concrete Structures by Means of <span class="hlt">Eddy</span> Current Testing</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>de Alcantara, Naasson P.; da Silva, Felipe M.; Guimarães, Mateus T.; Pereira, Matheus D.</p> <p>2015-01-01</p> <p>This paper presents a theoretical and experimental study on the use of <span class="hlt">Eddy</span> Current Testing (ECT) to evaluate corrosion processes in steel bars used in reinforced concrete structures. The paper presents the mathematical basis of the ECT sensor built by the authors; followed by a finite element analysis. The results obtained in the simulations are compared with those obtained in experimental tests performed by the authors. Effective resistances and inductances; voltage drops and phase angles of wound coil are calculated using both; simulated and experimental data; and demonstrate a strong <span class="hlt">correlation</span>. The production of samples of corroded steel bars; by using an impressed current <span class="hlt">technique</span> is also presented. The authors performed experimental tests in the laboratory using handmade sensors; and the corroded samples. In the tests four gauges; with five levels of loss-of-mass references for each one were used. The results are analyzed in the light of the loss-of-mass and show a strong linear behavior for the analyzed parameters. The conclusions emphasize the feasibility of the proposed <span class="hlt">technique</span> and highlight opportunities for future works. PMID:26712754</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26712754','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26712754"><span>Corrosion Assessment of Steel Bars Used in Reinforced Concrete Structures by Means of <span class="hlt">Eddy</span> Current Testing.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>de Alcantara, Naasson P; da Silva, Felipe M; Guimarães, Mateus T; Pereira, Matheus D</p> <p>2015-12-24</p> <p>This paper presents a theoretical and experimental study on the use of <span class="hlt">Eddy</span> Current Testing (ECT) to evaluate corrosion processes in steel bars used in reinforced concrete structures. The paper presents the mathematical basis of the ECT sensor built by the authors; followed by a finite element analysis. The results obtained in the simulations are compared with those obtained in experimental tests performed by the authors. Effective resistances and inductances; voltage drops and phase angles of wound coil are calculated using both; simulated and experimental data; and demonstrate a strong <span class="hlt">correlation</span>. The production of samples of corroded steel bars; by using an impressed current <span class="hlt">technique</span> is also presented. The authors performed experimental tests in the laboratory using handmade sensors; and the corroded samples. In the tests four gauges; with five levels of loss-of-mass references for each one were used. The results are analyzed in the light of the loss-of-mass and show a strong linear behavior for the analyzed parameters. The conclusions emphasize the feasibility of the proposed <span class="hlt">technique</span> and highlight opportunities for future works.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007PhDT.......104A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007PhDT.......104A"><span><span class="hlt">Eddy</span> current spectroscopy for near-surface residual stress profiling in surface treated nonmagnetic engine alloys</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Abu-Nabah, Bassam A.</p> <p></p> <p>Recent research results indicated that <span class="hlt">eddy</span> current conductivity measurements can be exploited for nondestructive evaluation of near-surface residual stresses in surface-treated nickel-base superalloy components. Most of the previous experimental studies were conducted on highly peened (Almen 10-16A) specimens that exhibit harmful cold work in excess of 30% plastic strain. Such high level of cold work causes thermo-mechanical relaxation at relatively modest operational temperatures; therefore the obtained results were not directly relevant to engine manufacturers and end users. The main reason for choosing peening intensities in excess of recommended normal levels was that in low-conductivity engine alloys the <span class="hlt">eddy</span> current penetration depth could not be forced below 0.2 mm without expanding the measurements above 10 MHz which is beyond the operational range of most commercial <span class="hlt">eddy</span> current instruments. As for shot-peened components, it was initially felt that the residual stress effect was more difficult to separate from cold work, texture, and inhomogeneity effects in titanium alloys than in nickel-base superalloys. In addition, titanium alloys have almost 50% lower electric conductivity than nickel-base superalloys; therefore require proportionally higher inspection frequencies, which was not feasible until our recent breakthrough in instrument development. Our work has been focused on six main aspects of this continuing research, namely, (i) the development of an iterative inversion <span class="hlt">technique</span> to better retrieve the depth-dependent conductivity profile from the measured frequency-dependent apparent <span class="hlt">eddy</span> current conductivity (AECC), (ii) the extension of the frequency range up to 80 MHz to better capture the peak compressive residual stress in nickel-base superalloys using a new <span class="hlt">eddy</span> current conductivity measuring system, which offers better reproducibility, accuracy and measurement speed than the previously used conventional systems, (iii) the lift-off effect on</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040111964&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DEddy%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040111964&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DEddy%2Bcurrent"><span>Corrosion Detection in Airframes Using a New Flux-Focusing <span class="hlt">Eddy</span> Current Probe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fulton, James P.; Wincheski, Buzz; Nath, Shridhar; Namkung, Min</p> <p>1994-01-01</p> <p> panels which may contain air gaps between the layers. Since the probe utilized <span class="hlt">eddy</span> currents its corrosion detection capabilities are similar to convectional <span class="hlt">eddy</span> current <span class="hlt">techniques</span>, but the new probe is much easier to use.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPC.1949p0003K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPC.1949p0003K"><span>Post-tensioning tendon force loss detection using low power pulsed <span class="hlt">eddy</span> current measurement</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Ji-Min; Lee, Jun; Sohn, Hoon</p> <p>2018-04-01</p> <p>In the field of bridge engineering, pre-fabrication of a bridge member and its construction in site have been issued and studied, which achieves improved quality and rapid construction. For integration of those pre-fabricated segments into a structural member (i.e., a concrete slab, girder and pier), post-tensioning (PT) <span class="hlt">technique</span> is adopted utilizing a high-strength steel tendon, and an effective investigation of the remaining PT tendon force is essential to assure an overall structural integrity. This study proposes a pulsed <span class="hlt">eddy</span> current based tendon force loss detection system. A compact <span class="hlt">eddy</span> current sensor is designed to be installed on the surface of an anchor holding a steel PT tendon. The intensity of the induced <span class="hlt">eddy</span> current varies with PT tendon force alteration due to the magnetostriction effect of a ferromagnetic material. The advantages of the proposed system are as follows: (1) low power consumption, (2) rapid inspection, and (3) simple installation. Its performance was validated experimentally in a full-scale lab test of a 3.3-m long, 15.2-mm diameter mono-tendon that was tensioned using a universal testing machine. Tendon force was controlled from 20 to 180 kN with 20 kN interval, and <span class="hlt">eddy</span> current responses were measured and analyzed at each force condition. The proposed damage index and the amount of force loss of PT tendon were monotonically related, and an excessive loss as much as 30 % of an initially-introduced tendon force was successfully predicted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000039436','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000039436"><span>Scale-Similar Models for Large-<span class="hlt">Eddy</span> Simulations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Sarghini, F.</p> <p>1999-01-01</p> <p>Scale-similar models employ multiple filtering operations to identify the smallest resolved scales, which have been shown to be the most active in the interaction with the unresolved subgrid scales. They do not assume that the principal axes of the strain-rate tensor are aligned with those of the subgrid-scale stress (SGS) tensor, and allow the explicit calculation of the SGS energy. They can provide backscatter in a numerically stable and physically realistic manner, and predict SGS stresses in regions that are well <span class="hlt">correlated</span> with the locations where large Reynolds stress occurs. In this paper, <span class="hlt">eddy</span> viscosity and mixed models, which include an <span class="hlt">eddy</span>-viscosity part as well as a scale-similar contribution, are applied to the simulation of two flows, a high Reynolds number plane channel flow, and a three-dimensional, nonequilibrium flow. The results show that simulations without models or with the Smagorinsky model are unable to predict nonequilibrium effects. Dynamic models provide an improvement of the results: the adjustment of the coefficient results in more accurate prediction of the perturbation from equilibrium. The Lagrangian-ensemble approach [Meneveau et al., J. Fluid Mech. 319, 353 (1996)] is found to be very beneficial. Models that included a scale-similar term and a dissipative one, as well as the Lagrangian ensemble averaging, gave results in the best agreement with the direct simulation and experimental data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17477838','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17477838"><span>Fluorescence <span class="hlt">correlation</span> spectroscopy: novel variations of an established <span class="hlt">technique</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Haustein, Elke; Schwille, Petra</p> <p>2007-01-01</p> <p>Fluorescence <span class="hlt">correlation</span> spectroscopy (FCS) is one of the major biophysical <span class="hlt">techniques</span> used for unraveling molecular interactions in vitro and in vivo. It allows minimally invasive study of dynamic processes in biological specimens with extremely high temporal and spatial resolution. By recording and <span class="hlt">correlating</span> the fluorescence fluctuations of single labeled molecules through the exciting laser beam, FCS gives information on molecular mobility and photophysical and photochemical reactions. By using dual-color fluorescence cross-<span class="hlt">correlation</span>, highly specific binding studies can be performed. These have been extended to four reaction partners accessible by multicolor applications. Alternative detection schemes shift accessible time frames to slower processes (e.g., scanning FCS) or higher concentrations (e.g., TIR-FCS). Despite its long tradition, FCS is by no means dated. Rather, it has proven to be a highly versatile <span class="hlt">technique</span> that can easily be adapted to solve specific biological questions, and it continues to find exciting applications in biology and medicine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMOS24B..03D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMOS24B..03D"><span><span class="hlt">Eddy</span>-induced Sea Surface Salinity changes in the tropical Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Delcroix, T. C.; Chaigneau, A.; Soviadan, D.; Boutin, J.</p> <p>2017-12-01</p> <p>We analyse the Sea Surface Salinity (SSS) signature of westward propagating mesoscale <span class="hlt">eddies</span> in the tropical Pacific by collocating 5 years (2010-2015) of SMOS (Soil Moisture and Ocean Salinity) SSS and altimetry-derived sea level anomalies. The main characteristics of mesoscale <span class="hlt">eddies</span> are first identified in SLA maps. Composite analyses in the Central and Eastern ITCZ regions then reveal regionally dependent impacts with opposite SSS anomalies for the cyclonic and anticyclonic <span class="hlt">eddies</span>. In the Central region (where we have the largest meridional SSS gradient), we found dipole-like SSS changes with maximum anomalies on the leading edge of the <span class="hlt">eddy</span>. In the Eastern region (where we have the largest near-surface vertical salinity gradient) we found monopole-like SSS changes with maximum anomalies in the <span class="hlt">eddy</span> centre. These dipole/monopole patterns and the rotational sense of <span class="hlt">eddies</span> suggest the dominant role of horizontal and vertical advection in the Central and Eastern ITCZ regions, respectively.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015OcDyn..65.1335G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015OcDyn..65.1335G"><span>Impacts of mesoscale <span class="hlt">eddies</span> in the South China Sea on biogeochemical cycles</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Guo, Mingxian; Chai, Fei; Xiu, Peng; Li, Shiyu; Rao, Shivanesh</p> <p>2015-09-01</p> <p>Biogeochemical cycles associated with mesoscale <span class="hlt">eddies</span> in the South China Sea (SCS) were investigated. The study was based on a coupled physical-biogeochemical Pacific Ocean model (Regional Ocean Model System-Carbon, Silicate, and Nitrogen Ecosystem, ROMS-CoSiNE) simulation for the period from 1991 to 2008. A total of 568 mesoscale <span class="hlt">eddies</span> with lifetime longer than 30 days were used in the analysis. Composite analysis revealed that the cyclonic <span class="hlt">eddies</span> were associated with abundance of nutrients, phytoplankton, and zooplankton while the anticyclonic <span class="hlt">eddies</span> depressed biogeochemical cycles, which are generally controlled by the <span class="hlt">eddy</span> pumping mechanism. In addition, diatoms were dominant in phytoplankton species due to the abundance of silicate. Dipole structures of vertical fluxes with net upward motion in cyclonic <span class="hlt">eddies</span> and net downward motion in anticyclonic <span class="hlt">eddies</span> were revealed. During the lifetime of an <span class="hlt">eddy</span>, the evolutions of physical, biological, and chemical structures were not linearly coupled at the <span class="hlt">eddy</span> core where plankton grew, and composition of the community depended not only on the physical and chemical processes but also on the adjustments by the predator-prey relationship.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=341342','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=341342"><span>Flux variance partitioning: a new approach to advance <span class="hlt">eddy</span> covariance observations for greenhouse gas emissions</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p><span class="hlt">Eddy</span> covariance (EC) is a well-established, non-intrusive observational <span class="hlt">technique</span> that has long been used to measure the net carbon balance of numerous ecosystems including crop lands for perennial crops such as orchards and vineyards, and pasturelands. While EC measures net carbon fluxes well, it ...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009EGUGA..1111428B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009EGUGA..1111428B"><span>Internal and forced <span class="hlt">eddy</span> variability in the Labrador Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bracco, A.; Luo, H.; Zhong, Y.; Lilly, J.</p> <p>2009-04-01</p> <p>Water mass transformation in the Labrador Sea, widely believed to be one of the key regions in the Atlantic Meridional Overturning Circulation (AMOC), now appears to be strongly impacted by vortex dynamics of the unstable boundary current. Large interannual variations in both <span class="hlt">eddy</span> shedding and buoyancy transport from the boundary current have been observed but not explained, and are apparently sensitive to the state of the inflowing current. Heat and salinity fluxes associated with the <span class="hlt">eddies</span> drive ventilation changes not accounted for by changes in local surface forcing, particularly during occasional years of extreme <span class="hlt">eddy</span> activity, and constitute a predominant source of "internal" oceanic variability. The nature of this variable <span class="hlt">eddy</span>-driven restratification is one of the outstanding questions along the northern transformation pathway. Here we investigate the <span class="hlt">eddy</span> generation mechanism and the associated buoyancy fluxes by combining realistic and idealized numerical modeling, data analysis, and theory. Theory, supported by idealized experiments, provides criteria to test hypotheses as to the vortex formation process (by baroclinic instability linked to the bottom topography). Ensembles of numerical experiments with a high-resolution regional model (ROMS) allow for quantifying the sensitivity of <span class="hlt">eddy</span> generation and property transport to variations in local and external forcing parameters. For the first time, we reproduce with a numerical simulation the observed interannual variability in the <span class="hlt">eddy</span> kinetic energy in the convective region of the Labrador Basin and along the West Greenland Current.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.8182M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.8182M"><span>Observations of the interaction between near-inertial waves and mesoscale <span class="hlt">eddies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Martínez-Marrero, Antonio; Sangrá, Pablo; Caldeira, Rui; Aguiar-González, Borja; Rodríguez-Santana, Ángel</p> <p>2014-05-01</p> <p>Trajectories of eight drifters dragged below the surface mixed layer and current meter data from a mooring are used to analyse the interaction between near-inertial waves and mesoscale <span class="hlt">eddies</span>. Drifters were deployed within <span class="hlt">eddies</span> generated downstream of Canary and Madeira islands between 1998 and 2007. The mooring was installed in the passage of cyclonic <span class="hlt">eddies</span> induced by Gran Canaria island during 2006. Rotatory wavelet analysis of Lagrangian velocities shows a clear relationship between the near-inertial waves' intrinsic frequencies and the <span class="hlt">eddy</span> angular velocities. The results reveal that near-inertial waves reach a minimum frequency of half the planetary vorticity (f/2) in the inner core of young anticyclonic <span class="hlt">eddies</span> rotating with its maximum absolute angular speed of f/2. The highest amplitudes of the observed inertial motions are also found within anticyclonic <span class="hlt">eddies</span> evidencing the trapping of inertial waves. Finally, the analysis of the current meter series show frequency fluctuations of the near-inertial currents in the upper 500 meters that are related to the passage of cyclonic <span class="hlt">eddies</span>. These fluctuations appear to be consistent with the variation of the background vorticity produced by the <span class="hlt">eddies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/ADA535734','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/ADA535734"><span>Winds, <span class="hlt">Eddies</span> and Flow through Straits</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2010-01-01</p> <p>driven origin of the Philippine dipole <span class="hlt">eddies</span>. By contrast, in other volcanic island regions of the world (including the Hawaiian, Cabo Verde, and... volcanic island regions of the world. By contrast in the Hawaiian, Cabo Verde and Canary Islands, the driving mechanism in the <span class="hlt">eddy</span> dynamics is...J. Aristegui, and F. Herrera (2000), Lee region of Gran Canaria , J. Geophys. Res., 105(C7), 17173-17193. Chang, C.-P., Z. Wang, and H. Hendon</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B13E0656B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B13E0656B"><span>Combined chamber-tower approach: Using <span class="hlt">eddy</span> covariance measurements to cross-validate carbon fluxes modeled from manual chamber campaigns</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brümmer, C.; Moffat, A. M.; Huth, V.; Augustin, J.; Herbst, M.; Kutsch, W. L.</p> <p>2016-12-01</p> <p>Manual carbon dioxide flux measurements with closed chambers at scheduled campaigns are a versatile method to study management effects at small scales in multiple-plot experiments. The <span class="hlt">eddy</span> covariance <span class="hlt">technique</span> has the advantage of quasi-continuous measurements but requires large homogeneous areas of a few hectares. To evaluate the uncertainties associated with interpolating from individual campaigns to the whole vegetation period, we installed both <span class="hlt">techniques</span> at an agricultural site in Northern Germany. The presented comparison covers two cropping seasons, winter oilseed rape in 2012/13 and winter wheat in 2013/14. Modeling half-hourly carbon fluxes from campaigns is commonly performed based on non-linear regressions for the light response and respiration. The daily averages of net CO2 modeled from chamber data deviated from <span class="hlt">eddy</span> covariance measurements in the range of ± 5 g C m-2 day-1. To understand the observed differences and to disentangle the effects, we performed four additional setups (expert versus default settings of the non-linear regressions based algorithm, purely empirical modeling with artificial neural networks versus non-linear regressions, cross-validating using <span class="hlt">eddy</span> covariance measurements as campaign fluxes, weekly versus monthly scheduling of campaigns) to model the half-hourly carbon fluxes for the whole vegetation period. The good agreement of the seasonal course of net CO2 at plot and field scale for our agricultural site demonstrates that both <span class="hlt">techniques</span> are robust and yield consistent results at seasonal time scale even for a managed ecosystem with high temporal dynamics in the fluxes. This allows combining the respective advantages of factorial experiments at plot scale with dense time series data at field scale. Furthermore, the information from the quasi-continuous <span class="hlt">eddy</span> covariance measurements can be used to derive vegetation proxies to support the interpolation of carbon fluxes in-between the manual chamber campaigns.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BGeo...14.5595B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BGeo...14.5595B"><span>Continuous measurement of air-water gas exchange by underwater <span class="hlt">eddy</span> covariance</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Berg, Peter; Pace, Michael L.</p> <p>2017-12-01</p> <p> mixing. This effect is unaccounted for in widely used empirical <span class="hlt">correlations</span> for gas exchange coefficients and is another source of uncertainty in gas exchange estimates. The aquatic <span class="hlt">eddy</span> covariance <span class="hlt">technique</span> allows studies of air-water gas exchange processes and their controls at an unparalleled level of detail. A finding related to the new approach is that heat fluxes at the air-water interface can, contrary to those typically found in the benthic environment, be substantial and require correction of O2 sensor readings using high-speed parallel temperature measurements. Fast-responding O2 sensors are inherently sensitive to temperature changes, and if this correction is omitted, temperature fluctuations associated with the turbulent heat flux will mistakenly be recorded as O2 fluctuations and bias the O2 <span class="hlt">eddy</span> flux calculation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840000138&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DEddy%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840000138&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DEddy%2Bcurrent"><span><span class="hlt">Eddy</span>-Current Reference Standard</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ambrose, H. H., Jr.</p> <p>1985-01-01</p> <p>Magnetic properties of metallic reference standards duplicated and stabilized for <span class="hlt">eddy</span>-current coil measurements over long times. Concept uses precisely machined notched samples of known annealed materials as reference standards.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li class="active"><span>14</span></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_14 --> <div id="page_15" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="281"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/7222766','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/7222766"><span>Harmonics suppression of vacuum chamber <span class="hlt">eddy</span> current induced fields with application to the Superconducting Super Collider (SSC) Low Energy Booster (LEB) Magnets</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Schlueter, R.D.; Halbach, K.</p> <p>1991-12-04</p> <p>This memo presents the formulation of an expression for <span class="hlt">eddy</span> currents induced in a thin-walled conductor due to a time-dependent electromagnet field excitation. Then follows an analytical development for prediction of vacuum chamber <span class="hlt">eddy</span> current induced field harmonics in iron-core electromagnets. A passive <span class="hlt">technique</span> for harmonics suppression is presented with specific application to the design of the Superconducting Super Collider (SSC) Low Energy B (LEB) Magnets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhFl...30d0909J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhFl...30d0909J"><span>Large <span class="hlt">eddy</span> simulation of spanwise rotating turbulent channel flow with dynamic variants of <span class="hlt">eddy</span> viscosity model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Jiang, Zhou; Xia, Zhenhua; Shi, Yipeng; Chen, Shiyi</p> <p>2018-04-01</p> <p>A fully developed spanwise rotating turbulent channel flow has been numerically investigated utilizing large-<span class="hlt">eddy</span> simulation. Our focus is to assess the performances of the dynamic variants of <span class="hlt">eddy</span> viscosity models, including dynamic Vreman's model (DVM), dynamic wall adapting local <span class="hlt">eddy</span> viscosity (DWALE) model, dynamic σ (Dσ ) model, and the dynamic volumetric strain-stretching (DVSS) model, in this canonical flow. The results with dynamic Smagorinsky model (DSM) and direct numerical simulations (DNS) are used as references. Our results show that the DVM has a wrong asymptotic behavior in the near wall region, while the other three models can correctly predict it. In the high rotation case, the DWALE can get reliable mean velocity profile, but the turbulence intensities in the wall-normal and spanwise directions show clear deviations from DNS data. DVSS exhibits poor predictions on both the mean velocity profile and turbulence intensities. In all three cases, Dσ performs the best.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/18472446','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/18472446"><span>[Comparison of <span class="hlt">eddy</span> covariance and static chamber/gas chromatogram methods in measuring ecosystem respiration].</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zheng, Ze-Mei; Yu, Gui-Rui; Sun, Xiao-Min; Cao, Guang-Min; Wang, Yue-Si; Du, Ming-Yuan; Li, Jun; Li, Ying-Nian</p> <p>2008-02-01</p> <p>Based on the measurement of carbon flux by the methods of <span class="hlt">eddy</span> covariance and static chamber/gas chromatogram, a comparison was made between the two methods in evaluating ecosystem respiration over winter wheat (Triticum aestivum)--summer maize (Zea mays) double cropland and Kobresia humilis alpine meadow. The results showed that under the conditions of obtained data having good quality, nighttime ecosystem respiration from <span class="hlt">eddy</span> covariance measurement was significantly agreed with that from static chamber/gas chromatogram measurement, with the <span class="hlt">correlation</span> coefficients ranging from 0.95 to 0.98, and the daytime ecosystem respiration from these two measurements also had a good consistency though the static chamber/gas chromatogram measurement often produced higher values. The daily mean value of ecosystem respiration was significantly different between these two measurements, but the seasonal pattern was similar. For winter wheat-summer maize double cropland, the difference of mean air temperature inside and outside the chamber was 1.8 degrees C, and the daily mean value of ecosystem respiration across the whole study period was 30.3% lower in <span class="hlt">eddy</span> covariance measurement than in static chamber/gas chromatogram measurement; while for alpine meadow, the difference of the mean air temperature was 1.9 degrees C, and the daily mean value of ecosystem respiration was 31.4% lower in <span class="hlt">eddy</span> covariance measurement than in static chamber/gas chromatogram measurement. The variance between the daily mean values of ecosystem respiration obtained from the two measurements was higher in growing season than in dormant season.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940019674','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940019674"><span>Large-<span class="hlt">eddy</span> simulation of flow in a plane, asymmetric diffuser</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kaltenbach, Hans-Jakob</p> <p>1993-01-01</p> <p>Recent improvements in subgrid-scale modeling as well as increases in computer power make it feasible to investigate flows using large-<span class="hlt">eddy</span> simulation (LES) which have been traditionally studied with <span class="hlt">techniques</span> based on Reynolds averaging. However, LES has not yet been applied to many flows of immediate technical interest. Preliminary results from LES of a plane diffuser flow are described. The long term goal of this work is to investigate flow separation as well as separation control in ducts and ramp-like geometries.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.2517S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.2517S"><span>Automatic tracking of dynamical evolutions of oceanic mesoscale <span class="hlt">eddies</span> with satellite observation data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sun, Liang; Li, Qiu-Yang</p> <p>2017-04-01</p> <p>The oceanic mesoscale <span class="hlt">eddies</span> play a major role in ocean climate system. To analyse spatiotemporal dynamics of oceanic mesoscale <span class="hlt">eddies</span>, the Genealogical Evolution Model (GEM) based on satellite data is developed, which is an efficient logical model used to track dynamic evolution of mesoscale <span class="hlt">eddies</span> in the ocean. It can distinguish different dynamic processes (e.g., merging and splitting) within a dynamic evolution pattern, which is difficult to accomplish using other tracking methods. To this end, a mononuclear <span class="hlt">eddy</span> detection method was firstly developed with simple segmentation strategies, e.g. watershed algorithm. The algorithm is very fast by searching the steepest descent path. Second, the GEM uses a two-dimensional similarity vector (i.e. a pair of ratios of overlap area between two <span class="hlt">eddies</span> to the area of each <span class="hlt">eddy</span>) rather than a scalar to measure the similarity between <span class="hlt">eddies</span>, which effectively solves the ''missing <span class="hlt">eddy</span>" problem (temporarily lost <span class="hlt">eddy</span> in tracking). Third, for tracking when an <span class="hlt">eddy</span> splits, GEM uses both "parent" (the original <span class="hlt">eddy</span>) and "child" (<span class="hlt">eddy</span> split from parent) and the dynamic processes are described as birth and death of different generations. Additionally, a new look-ahead approach with selection rules effectively simplifies computation and recording. All of the computational steps are linear and do not include iteration. Given the pixel number of the target region L, the maximum number of <span class="hlt">eddies</span> M, the number N of look-ahead time steps, and the total number of time steps T, the total computer time is O (LM(N+1)T). The tracking of each <span class="hlt">eddy</span> is very smooth because we require that the snapshots of each <span class="hlt">eddy</span> on adjacent days overlap one another. Although <span class="hlt">eddy</span> splitting or merging is ubiquitous in the ocean, they have different geographic distribution in the Northern Pacific Ocean. Both the merging and splitting rates of the <span class="hlt">eddies</span> are high, especially at the western boundary, in currents and in "<span class="hlt">eddy</span> deserts". GEM is useful not only for</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUFM.B41B0403D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUFM.B41B0403D"><span>An Extensible Processing Framework for <span class="hlt">Eddy</span>-covariance Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Durden, D.; Fox, A. M.; Metzger, S.; Sturtevant, C.; Durden, N. P.; Luo, H.</p> <p>2016-12-01</p> <p>The evolution of large data collecting networks has not only led to an increase of available information, but also in the complexity of analyzing the observations. Timely dissemination of readily usable data products necessitates a streaming processing framework that is both automatable and flexible. Tower networks, such as ICOS, Ameriflux, and NEON, exemplify this issue by requiring large amounts of data to be processed from dispersed measurement sites. <span class="hlt">Eddy</span>-covariance data from across the NEON network are expected to amount to 100 Gigabytes per day. The complexity of the algorithmic processing necessary to produce high-quality data products together with the continued development of new analysis <span class="hlt">techniques</span> led to the development of a modular R-package, <span class="hlt">eddy</span>4R. This allows algorithms provided by NEON and the larger community to be deployed in streaming processing, and to be used by community members alike. In order to control the processing environment, provide a proficient parallel processing structure, and certify dependencies are available during processing, we chose Docker as our "Development and Operations" (DevOps) platform. The Docker framework allows our processing algorithms to be developed, maintained and deployed at scale. Additionally, the <span class="hlt">eddy</span>4R-Docker framework fosters community use and extensibility via pre-built Docker images and the Github distributed version control system. The capability to process large data sets is reliant upon efficient input and output of data, data compressibility to reduce compute resource loads, and the ability to easily package metadata. The Hierarchical Data Format (HDF5) is a file format that can meet these needs. A NEON standard HDF5 file structure and metadata attributes allow users to explore larger data sets in an intuitive "directory-like" structure adopting the NEON data product naming conventions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19870009329','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19870009329"><span><span class="hlt">Eddy</span> currents in a conducting sphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bergman, John; Hestenes, David</p> <p>1986-01-01</p> <p>This report analyzes the <span class="hlt">eddy</span> current induced in a solid conducting sphere by a sinusoidal current in a circular loop. Analytical expressions for the <span class="hlt">eddy</span> currents are derived as a power series in the vectorial displacement of the center of the sphere from the axis of the loop. These are used for first order calculations of the power dissipated in the sphere and the force and torque exerted on the sphere by the electromagnetic field of the loop.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017OcDyn..67.1313C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017OcDyn..67.1313C"><span>Benchmarking the mesoscale variability in global ocean <span class="hlt">eddy</span>-permitting numerical systems</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cipollone, Andrea; Masina, Simona; Storto, Andrea; Iovino, Doroteaciro</p> <p>2017-10-01</p> <p>The role of data assimilation procedures on representing ocean mesoscale variability is assessed by applying <span class="hlt">eddy</span> statistics to a state-of-the-art global ocean reanalysis (C-GLORS), a free global ocean simulation (performed with the NEMO system) and an observation-based dataset (ARMOR3D) used as an independent benchmark. Numerical results are computed on a 1/4 ∘ horizontal grid (ORCA025) and share the same resolution with ARMOR3D dataset. This "<span class="hlt">eddy</span>-permitting" resolution is sufficient to allow ocean <span class="hlt">eddies</span> to form. Further to assessing the <span class="hlt">eddy</span> statistics from three different datasets, a global three-dimensional <span class="hlt">eddy</span> detection system is implemented in order to bypass the need of regional-dependent definition of thresholds, typical of commonly adopted <span class="hlt">eddy</span> detection algorithms. It thus provides full three-dimensional <span class="hlt">eddy</span> statistics segmenting vertical profiles from local rotational velocities. This criterion is crucial for discerning real <span class="hlt">eddies</span> from transient surface noise that inevitably affects any two-dimensional algorithm. Data assimilation enhances and corrects mesoscale variability on a wide range of features that cannot be well reproduced otherwise. The free simulation fairly reproduces <span class="hlt">eddies</span> emerging from western boundary currents and deep baroclinic instabilities, while underestimates shallower vortexes that populate the full basin. The ocean reanalysis recovers most of the missing turbulence, shown by satellite products , that is not generated by the model itself and consistently projects surface variability deep into the water column. The comparison with the statistically reconstructed vertical profiles from ARMOR3D show that ocean data assimilation is able to embed variability into the model dynamics, constraining <span class="hlt">eddies</span> with in situ and altimetry observation and generating them consistently with local environment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.6165H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.6165H"><span>Temporal evolution of near-surface chlorophyll over cyclonic <span class="hlt">eddy</span> lifecycles in the southeastern Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huang, Jie; Xu, Fanghua; Zhou, Kuanbo; Xiu, Peng; Lin, Yanluan</p> <p>2017-08-01</p> <p>Temporal evolution of near-surface chlorophyll (CHL) associated with mesoscale <span class="hlt">eddies</span> over entire <span class="hlt">eddy</span> lifespan is complicated. Based on satellite measurements and a reanalysis data set, we identify and quantify major temporal and spatial CHL responses in cyclonic <span class="hlt">eddies</span> in the southeastern Pacific, and explore the associated mechanisms. Only few temporal CHL variations can be directly linked to the four primary mechanisms: "<span class="hlt">eddy</span> pumping," "<span class="hlt">eddy</span> trapping," "<span class="hlt">eddy</span> stirring," and "<span class="hlt">eddy</span>-induced Ekman pumping." About 80% of the temporal CHL variations are too complex to be explained by a single mechanism. Five characteristic CHL responses, including classic dipoles (CD), positive-dominant dipoles (PD), negative-dominant dipoles (ND), positive monopoles (PM), and negative monopoles (NM) are identified using the self-organizing map (SOM). CD, a dominant response induced primarily by "<span class="hlt">eddy</span> stirring," has a continued increasing of frequency of occurrence with time, although its contribution to the total CHL variability remains low. As the secondary prominent response, NM has two peaks of frequency of occurrence at <span class="hlt">eddy</span> formation and maturation stages, mainly accounted by "<span class="hlt">eddy</span> trapping" after <span class="hlt">eddy</span> breakup and "<span class="hlt">eddy</span>-induced Ekman pumping," respectively. The sum of frequency of occurrence of PD and PM are comparable to that of NM. The initial positive CHL at <span class="hlt">eddy</span> formation stage is associated with "<span class="hlt">eddy</span> trapping." The significant positive CHL increase from the <span class="hlt">eddy</span> intensification to early decay stage is mainly attributed to "<span class="hlt">eddy</span> pumping." Although the frequency of occurrence of ND is the smallest, its contribution to negative CHL anomalies is unnegligible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.B13D0209K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.B13D0209K"><span>Sediment-water gas exchange in two Swedish lakes measured by <span class="hlt">Eddy</span> <span class="hlt">Correlation</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kokic, J.; Sahlee, E.; Brand, A.; Sobek, S.</p> <p>2014-12-01</p> <p>Lake sediments are hotspots for carbon (C) cycling, acting both as sinks and sources through C burial and production of carbon dioxide (CO2) and methane. The fate of this CO2 in the water column is controlled by bottom water turbulence, a factor not accounted for in current estimates of sediment CO2 fluxes. This study is aimed to quantify the turbulent CO2 flux across the sediment-water interface (SWI) by measuring the oxygen (O2) flux with the non-invasive <span class="hlt">Eddy</span> <span class="hlt">Correlation</span> (EC) method that combines measurements of 3D velocity (ADV) and O2 fluctuations with a microsensor. Using the metabolic relation (respiratory quotient, RQ) of O2 and CO2 derived from a sediment incubation experiment we present the first estimates of turbulent lake sediment CO2 flux from two boreal lakes in Sweden (Erssjön and Erken, 0.07 km2 and 23.7 km2 respectively). Only ~10 % of the total dataset was extracted for flux calculations due to poor signal-to-noise ratio in the velocity and O2 signals. The sediment in Lake Erssjön was both consuming and producing O2, related to bacterial respiration and photosynthesis. Mean O2 flux was -0.19 and 0.17 μmol O2 m-2 sec-1, comparing to 0.04 μmol O2 m-2 sec-1 derived from the sediment incubation experiment. Fluxes for Lake Erken are still to be determined. Experimentally derived RQ of the both lake sediments were close to unity implying that in-situ CO2 fluxes are of similar magnitude as O2 fluxes, varying between -0.15 and 0.18 μmol C m-2 sec-1. The first measurement of turbulent sediment O2 flux and estimate of turbulent CO2 flux from a small boreal lake show higher and more variable fluxes than previously found in experimental studies. The low amount of data extracted for flux calculations (~10%) point towards the difficulties in EC measurement in low-turbulence environments. On-going work focuses on the turbulence structure in lakes and its influence on the gas fluxes at the SWI.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Eddy+AND+current&id=EJ185642','ERIC'); return false;" href="https://eric.ed.gov/?q=Eddy+AND+current&id=EJ185642"><span><span class="hlt">Eddy</span> Currents: Levitation, Metal Detectors, and Induction Heating</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Wouch, G.; Lord, A. E., Jr.</p> <p>1978-01-01</p> <p>A simple and accessible calculation is given of the effects of <span class="hlt">eddy</span> currents for a sphere in the field of a single circular loop of alternating current. These calculations should help toward the inclusion of <span class="hlt">eddy</span> current effects in upper undergraduate physics courses. (BB)</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930000710&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DEddy%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930000710&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DEddy%2Bcurrent"><span><span class="hlt">Eddy</span>-Current Measurement Of Turning Or Curvature</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chern, Engmin J.</p> <p>1993-01-01</p> <p>Rotatable conductive plate covers sensing coil to varying degree. Curvature of pipe at remote or otherwise inaccessible location inside pipe measured using relatively simple angular-displacement <span class="hlt">eddy</span>-current probe. Crawler and sensor assemblies move along inside of pipe on wheels. Conductive plate pivots to follow curvature of pipe, partly covering one of <span class="hlt">eddy</span>-current coils to degree depending on local curvature on pipe.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20070031760','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20070031760"><span>Analysis of <span class="hlt">Eddy</span> Current Capabilities for the Detection of Outer Diameter Stress Corrosion Cracking in Small Bore Metallic Structures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wincheski, Buzz; Williams, Phillip; Simpson, John</p> <p>2007-01-01</p> <p>The use of <span class="hlt">eddy</span> current <span class="hlt">techniques</span> for the detection of outer diameter damage in tubing and many complex aerospace structures often requires the use of an inner diameter probe due to a lack of access to the outside of the part. In small bore structures the probe size and orientation are constrained by the inner diameter of the part, complicating the optimization of the inspection <span class="hlt">technique</span>. Detection of flaws through a significant remaining wall thickness becomes limited not only by the standard depth of penetration, but also geometrical aspects of the probe. Recently, an orthogonal <span class="hlt">eddy</span> current probe was developed for detection of such flaws in Space Shuttle Primary Reaction Control System (PRCS) Thrusters. In this case, the detection of deeply buried stress corrosion cracking by an inner diameter <span class="hlt">eddy</span> current probe was sought. Probe optimization was performed based upon the limiting spatial dimensions, flaw orientation, and required detection sensitivity. Analysis of the probe/flaw interaction was performed through the use of finite and boundary element modeling <span class="hlt">techniques</span>. Experimental data for the flaw detection capabilities, including a probability of detection study, will be presented along with the simulation data. The results of this work have led to the successful deployment of an inspection system for the detection of stress corrosion cracking in Space Shuttle Primary Reaction Control System (PRCS) Thrusters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14..178K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14..178K"><span>Satellite observations of <span class="hlt">eddies</span> in the Baltic, Black and Caspian seas</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karimova, S.</p> <p>2012-04-01</p> <p>In the present paper mesoscale and sub-mesoscale <span class="hlt">eddies</span> in the Baltic, Black and Caspian seas are studied by means of satellite radiometer and radar images. Using these data makes it possible to investigate the vortical structures of a wide spatial range, from the basin scale through mesoscale to a small scale with a few kilometers in size. Over 2000 Envisat ASAR and ERS-2 SAR images with two-year time coverage (2009-2010) and spatial resolution of 75 m obtained in different parts of the Baltic, Black and Caspian Seas were applied to study submesoscale (with a diameter less than ca. 20 km) <span class="hlt">eddies</span> in the basins mentioned. As a result of the analysis performed the role of different mechanisms (ones due to surfactant films, wave/current interactions and thermal fronts) in <span class="hlt">eddy</span> visualization in SAR imagery was revealed. In every basin studied the main <span class="hlt">eddy</span> characteristics such as number of <span class="hlt">eddies</span>, frequency of their occurrence in SAR imagery, sign of vorticity, typical length scale and lifetime as well as spatial distribution patterns were investigated. Spatio-temporal parameters of the vortices were subjected to statistical analysis. Interannual and seasonal variabilities of the <span class="hlt">eddy</span> parameters were traced. Hypotheses about the most important mechanisms of generation of the <span class="hlt">eddies</span> observed were proposed. Among them there are barotropic, baroclinic and topographic instabilities, convection in the surface layer and heterogeneous wind forcing. Satellite infrared and visible images were used for retrieving statistical information on the Black Sea mesoscale vortical structures. The dataset used included ~5000 AVHRR NOAA Sea Surface Temperature (SST) images covering the entire Black Sea with time coverage since September, 2004 to December, 2010 and ~1500 MODIS Aqua (SST, normalized water-leaving radiance at 551 nm, chlorophyll-a concentration) images obtained in 2006-2010. Spatial resolution of the images was 1 km. Analysis performed revealed that numerous vortical</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=284117','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=284117"><span>A turnkey data logger program for field-scale energy flux density measurements using <span class="hlt">eddy</span> covariance and surface renewal</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Micrometeorological methods and ecosystem-scale energy and mass flux density measurements have become increasingly important in soil, agricultural, and environmental sciences. For many scientists without formal training in atmospheric science, these <span class="hlt">techniques</span> are relatively inaccessible. <span class="hlt">Eddy</span> cov...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AIPC.1581.1448R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AIPC.1581.1448R"><span>Determination of linear defect depths from <span class="hlt">eddy</span> currents disturbances</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ramos, Helena Geirinhas; Rocha, Tiago; Pasadas, Dário; Ribeiro, Artur Lopes</p> <p>2014-02-01</p> <p>One of the still open problems in the inspection research concerns the determination of the maximum depth to which a surface defect goes. <span class="hlt">Eddy</span> current testing being one of the most sensitive well established inspection methods, able to detect and characterize different type of defects in conductive materials, is an adequate <span class="hlt">technique</span> to solve this problem. This paper reports a study concerning the disturbances in the magnetic field and in the lines of current due to a machined linear defect having different depths in order to extract relevant information that allows the determination of the defect characteristics. The image of the <span class="hlt">eddy</span> currents (EC) is paramount to understand the physical phenomena involved. The EC images for this study are generated using a commercial finite element model (FLUX). The excitation used produces a uniform magnetic field on the plate under test in the absence of defects and the disturbances due to the defects are compared with those obtained from experimental measurements. In order to increase the limited penetration depth of the method giant magnetoresistors (GMR) are used to lower the working frequency. The geometry of the excitation planar coil produces a uniform magnetic field on an area of around the GMR sensor, inducing a uniform <span class="hlt">eddy</span> current distribution on the plate. In the presence of defects in the material surface, the lines of currents inside the material are deviated from their uniform direction and the magnetic field produced by these currents is sensed by the GMR sensor. Besides the theoretical study of the electromagnetic system, the paper describes the experiments that have been carried out to support the theory and conclusions are drawn for cracks having different depths.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19950059367&hterms=channels+distribution&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dchannels%2Bdistribution','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19950059367&hterms=channels+distribution&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dchannels%2Bdistribution"><span>The <span class="hlt">correlated</span> k-distribution <span class="hlt">technique</span> as applied to the AVHRR channels</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kratz, David P.</p> <p>1995-01-01</p> <p><span class="hlt">Correlated</span> k-distributions have been created to account for the molecular absorption found in the spectral ranges of the five Advanced Very High Resolution Radiometer (AVHRR) satellite channels. The production of the k-distributions was based upon an exponential-sum fitting of transmissions (ESFT) <span class="hlt">technique</span> which was applied to reference line-by-line absorptance calculations. To account for the overlap of spectral features from different molecular species, the present routines made use of the multiplication transmissivity property which allows for considerable flexibility, especially when altering relative mixing ratios of the various molecular species. To determine the accuracy of the <span class="hlt">correlated</span> k-distribution <span class="hlt">technique</span> as compared to the line-by-line procedure, atmospheric flux and heating rate calculations were run for a wide variety of atmospheric conditions. For the atmospheric conditions taken into consideration, the <span class="hlt">correlated</span> k-distribution <span class="hlt">technique</span> has yielded results within about 0.5% for both the cases where the satellite spectral response functions were applied and where they were not. The <span class="hlt">correlated</span> k-distribution's principal advantages is that it can be incorporated directly into multiple scattering routines that consider scattering as well as absorption by clouds and aerosol particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20000064114','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20000064114"><span>Investigation of Density Fluctuations in Supersonic Free Jets and <span class="hlt">Correlation</span> with Generated Noise</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Panda, J.; Seasholtz, R. G.</p> <p>2000-01-01</p> <p>The air density fluctuations in the plumes of fully-expanded, unheated free jets were investigated experimentally using a Rayleigh scattering based <span class="hlt">technique</span>. The point measuring <span class="hlt">technique</span> used a continuous wave laser, fiber-optic transmission and photon counting electronics. The radial and centerline profiles of time-averaged density and root-mean-square density fluctuation provided a comparative description of jet growth. To measure density fluctuation spectra a two-Photomultiplier tube <span class="hlt">technique</span> was used. Crosscorrelation between the two PMT signals significantly reduced electronic shot noise contribution. Turbulent density fluctuations occurring up to a Strouhal number (Sr) of 2.5 were resolved. A remarkable feature of density spectra, obtained from the same locations of jets in 0.5< M<1.5 range, is a constant Strouhal frequency for peak fluctuations. A detailed survey at Mach numbers M = 0.95, 1.4 and 1.8 showed that, in general, distribution of various Strouhal frequency fluctuations remained similar for the three jets. In spite of the similarity in the flow fluctuation the noise characteristics were found to be significantly different. Spark schlieren photographs and near field microphone measurements confirmed that the <span class="hlt">eddy</span> Mach wave radiation was present in Mach 1.8 jet, and was absent in Mach 0.95 jet. To measure <span class="hlt">correlation</span> between the flow and the far field sound pressure fluctuations, a microphone was kept at a distance of 50 diameters, 30 deg. to the flow direction, and the laser probe volume was moved from point to point in the flow. The density fluctuations in the peripheral shear layer of Mach 1.8 jet showed significant <span class="hlt">correlation</span> up to the measurement limit of Sr = 2.5, while for Mach 0.95 jet no <span class="hlt">correlation</span> was measured. Along the centerline measurable <span class="hlt">correlation</span> was found from the end of the potential core and at the low frequency range (Sr less than 0.5). Usually the normalized <span class="hlt">correlation</span> values increased with an increase of the jet Mach</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770012817','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770012817"><span>Study of photon <span class="hlt">correlation</span> <span class="hlt">techniques</span> for processing of laser velocimeter signals</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayo, W. T., Jr.</p> <p>1977-01-01</p> <p>The objective was to provide the theory and a system design for a new type of photon counting processor for low level dual scatter laser velocimeter (LV) signals which would be capable of both the first order measurements of mean flow and turbulence intensity and also the second order time statistics: cross <span class="hlt">correlation</span> auto <span class="hlt">correlation</span>, and related spectra. A general Poisson process model for low level LV signals and noise which is valid from the photon-resolved regime all the way to the limiting case of nonstationary Gaussian noise was used. Computer simulation algorithms and higher order statistical moment analysis of Poisson processes were derived and applied to the analysis of photon <span class="hlt">correlation</span> <span class="hlt">techniques</span>. A system design using a unique dual <span class="hlt">correlate</span> and subtract frequency discriminator <span class="hlt">technique</span> is postulated and analyzed. Expectation analysis indicates that the objective measurements are feasible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1916089V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1916089V"><span>Towards an integrated quality control procedure for <span class="hlt">eddy</span>-covariance data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Vitale, Domenico; Papale, Dario</p> <p>2017-04-01</p> <p>The <span class="hlt">eddy</span>-covariance <span class="hlt">technique</span> is nowadays the most reliable and direct way, allowing to calculate the main fluxes of Sensible and Latent Heat and of Net Ecosystem Exchange, this last being the result of the difference between the CO2 assimilated by photosynthetic activities and those released to the atmosphere through the ecosystem respiration processes. Despite the improvements in accuracy of measurement instruments and software development, the <span class="hlt">eddy</span>-covariance <span class="hlt">technique</span> is not suitable under non-ideal conditions respect to the instruments characteristics and the physical assumption behind the <span class="hlt">technique</span> mainly related to the well-developed and stationary turbulence conditions. Under these conditions the calculated fluxes are not reliable and need to be flagged and discarded. In order to discover these unavoidable "bad" fluxes and build dataset with the highest quality, several tests applied both on high-frequency (10-20 Hz) raw data and on half-hourly times series have been developed in the past years. Nevertheless, there is an increasing need to develop a standardized quality control procedure suitable not only for the analysis of long-term data, but also for the near-real time data processing. In this paper, we review established quality assessment procedures and present an innovative quality control strategy with the purpose of integrating the existing consolidated procedures with robust and advanced statistical tests more suitable for the analysis of time series data. The performance of the proposed quality control strategy is evaluated both on simulated and EC data distributed by the ICOS research infrastructure. It is concluded that the proposed strategy is able to flag and exclude unrealistic fluxes while being reproducible and retaining the largest possible amount of high quality data.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li class="active"><span>15</span></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_15 --> <div id="page_16" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="301"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996JAP....79.4678L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996JAP....79.4678L"><span>Solution of magnetic field and <span class="hlt">eddy</span> current problem induced by rotating magnetic poles (abstract)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Liu, Z. J.; Low, T. S.</p> <p>1996-04-01</p> <p>The magnetic field and <span class="hlt">eddy</span> current problems induced by rotating permanent magnet poles occur in electromagnetic dampers, magnetic couplings, and many other devices. Whereas numerical <span class="hlt">techniques</span>, for example, finite element methods can be exploited to study various features of these problems, such as heat generation and drag torque development, etc., the analytical solution is always of interest to the designers since it helps them to gain the insight into the interdependence of the parameters involved and provides an efficient tool for designing. Some of the previous work showed that the solution of the <span class="hlt">eddy</span> current problem due to the linearly moving magnet poles can give satisfactory approximation for the <span class="hlt">eddy</span> current problem due to rotating fields. However, in many practical cases, especially when the number of magnet poles is small, there is significant effect of flux focusing due to the geometry. The above approximation can therefore lead to marked errors in the theoretical predictions of the device performance. Bernot et al. recently described an analytical solution in a polar coordinate system where the radial field is excited by a time-varying source. A discussion of an analytical solution of the magnetic field and <span class="hlt">eddy</span> current problems induced by moving magnet poles in radial field machines will be given in this article. The theoretical predictions obtained from this method is compared with the results obtained from finite element calculations. The validity of the method is also checked by the comparison of the theoretical predictions and the measurements from a test machine. It is shown that the introduced solution leads to a significant improvement in the air gap field prediction as compared with the results obtained from the analytical solution that models the <span class="hlt">eddy</span> current problems induced by linearly moving magnet poles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OcDyn.tmp...50S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OcDyn.tmp...50S"><span><span class="hlt">Eddy</span> energy sources and mesoscale <span class="hlt">eddies</span> in the Sea of Okhotsk</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stepanov, Dmitry V.; Diansky, Nikolay A.; Fomin, Vladimir V.</p> <p>2018-05-01</p> <p>Based on <span class="hlt">eddy</span>-permitting ocean circulation model outputs, the mesoscale variability is studied in the Sea of Okhotsk. We confirmed that the simulated circulation reproduces the main features of the general circulation in the Sea of Okhotsk. In particular, it reproduced a complex structure of the East-Sakhalin current and the pronounced seasonal variability of this current. We established that the maximum of mean kinetic energy was associated with the East-Sakhalin Current. In order to uncover causes and mechanisms of the mesoscale variability, we studied the budget of <span class="hlt">eddy</span> kinetic energy (EKE) in the Sea of Okhotsk. Spatial distribution of the EKE showed that intensive mesoscale variability occurs along the western boundary of the Sea of Okhotsk, where the East-Sakhalin Current extends. We revealed a pronounced seasonal variability of EKE with its maximum intensity in winter and its minimum intensity in summer. Analysis of EKE sources and rates of energy conversion revealed a leading role of time-varying (turbulent) wind stress in the generation of mesoscale variability along the western boundary of the Sea of Okhotsk in winter and spring. We established that a contribution of baroclinic instability predominates over that of barotropic instability in the generation of mesoscale variability along the western boundary of the Sea of Okhotsk. To demonstrate the mechanism of baroclinic instability, the simulated circulation was considered along the western boundary of the Sea of Okhotsk from January to April 2005. In April, the mesoscale anticyclonic <span class="hlt">eddies</span> are observed along the western boundary of the Sea of Okhotsk. The role of the sea ice cover in the intensification of the mesoscale variability in the Sea of Okhotsk was discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011OcDyn..61..991G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011OcDyn..61..991G"><span><span class="hlt">Eddy</span> resolving modelling of the Gulf of Lions and Catalan Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Garreau, Pierre; Garnier, Valérie; Schaeffer, Amandine</p> <p>2011-07-01</p> <p>The generation process of strong long-lived <span class="hlt">eddies</span> flowing southwestwards along the Catalan slope was revealed through numerical modelling and in situ observations. Careful analyses of a particular event in autumn 2007 demonstrated a link between a "LATEX" <span class="hlt">eddy</span>, which remained in the southwestern corner of the Gulf of Lions and a "CATALAN" <span class="hlt">eddy</span>, which moved along the Catalan Shelf, since the death of the former gave birth to the latter. The origin of such <span class="hlt">eddies</span> was found to be an accumulation of potential energy in the southwestern corner of the Gulf of Lions: under the influence of the negative wind stress curl associated with the Tramontane, a warm and less dense water body can be isolated and fed by a coastal current carrying warm water from the Catalan Sea. In summer, this structure can grow and intensify to generate a strong anticyclonic <span class="hlt">eddy</span>. After a long period of Tramontane, a burst of southeasterlies and northerlies appeared to detach the "LATEX" <span class="hlt">eddy</span>, which flowed out of the Gulf of Lions, migrating along the Catalan continental slope and continued into the Balearic Sea as the "CATALAN" <span class="hlt">eddy</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016DPS....4821006B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016DPS....4821006B"><span>The Energetics of Transient <span class="hlt">Eddies</span> in the Martian Northern Hemisphere</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Battalio, Joseph Michael; Szunyogh, Istvan; Lemmon, Mark T.</p> <p>2016-10-01</p> <p>The energetics of northern hemisphere transient waves in the Mars Analysis Correction Data Assimilation is analyzed. Three periods between the fall and spring equinoxes (Ls=200°-230°, 255°-285°, and 330°-360°) during three Mars Years are selected to exemplify the fall, winter, and spring wave activity. Fall and spring <span class="hlt">eddy</span> energetics is similar with some inter-annual and inter-seasonal variability, but winter <span class="hlt">eddy</span> kinetic energy and its transport are strongly reduced in intensity as a result of the solsticial pause in <span class="hlt">eddy</span> activity. Barotropic energy conversion acts as a sink of <span class="hlt">eddy</span> kinetic energy throughout the northern hemisphere <span class="hlt">eddy</span> period with little reduction in amplitude during the solsticial pause. Baroclinic energy conversion acts as a source in fall and spring but disappears during the winter period as a result of the stabilized vertical shear profile of the westerly jet around winter solstice.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996SPIE.2945..235H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996SPIE.2945..235H"><span>Improved NDI <span class="hlt">techniques</span> for aircraft inspections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hagemaier, Donald J.; Wilson, Dwight</p> <p>1996-11-01</p> <p>Through the use of an 'integrated product team' approach and new inspection <span class="hlt">techniques</span> incorporating the latest in imaging capabilities and automation, the costs of some man- power intensive tasks can now be drastically reduced. Also, through the use of advanced <span class="hlt">eddy</span> current <span class="hlt">techniques</span>, the detectable size of cracks under flush-head fasteners can be reduced while maintaining a reliable inspection. Early in this decade, the FAA Technical Center and NASA LaRC formulated an aging aircraft research plan. The unique aspect about the research is that it is driven by the aircraft manufacturers and airlines in order to center only on those areas in which help is needed and to keep it focused. Once developed, the manufacturer works with the FAA Validation Center at Sandia National Labs., the airline, and the researcher to transfer technology to the field. This article describes the evaluation and results obtained using <span class="hlt">eddy</span> current technology to determine the minimum detectable crack size under installed flush-head fasteners. Secondly, it describes the integrated efforts of engineers at McDonnell Douglas Aerospace and Northwest Airlines in the successful application of MAUS <span class="hlt">eddy</span> current C-scanning of the DC-10 circumferential and axial crown splices. The <span class="hlt">eddy</span> current C-scanning greatly reduced the man-hour effort required for the existing radiographic inspection. Thirdly, it describes the use of a novel ultrasonic <span class="hlt">technique</span> coupled to a scanner and graphics for the detection and quantification of corrosion thinning and stress corrosion cracking of the DC-9 lower wing tee cap. This successful effort resulted from a rather large integrated task team. It also results in a vast man-hour savings over the existing internal visual inspection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20357833','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20357833"><span>Mesoscale <span class="hlt">eddies</span>: hotspots of prokaryotic activity and differential community structure in the ocean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Baltar, Federico; Arístegui, Javier; Gasol, Josep M; Lekunberri, Itziar; Herndl, Gerhard J</p> <p>2010-08-01</p> <p>To investigate the effects of mesoscale <span class="hlt">eddies</span> on prokaryotic assemblage structure and activity, we sampled two cyclonic <span class="hlt">eddies</span> (CEs) and two anticyclonic <span class="hlt">eddies</span> (AEs) in the permanent <span class="hlt">eddy</span>-field downstream the Canary Islands. The <span class="hlt">eddy</span> stations were compared with two far-field (FF) stations located also in the Canary Current, but outside the influence of the <span class="hlt">eddy</span> field. The distribution of prokaryotic abundance (PA), bulk prokaryotic heterotrophic activity (PHA), various indicators of single-cell activity (such as nucleic acid content, proportion of live cells, and fraction of cells actively incorporating leucine), as well as bacterial and archaeal community structure were determined from the surface to 2000 m depth. In the upper epipelagic layer (0-200 m), the effect of <span class="hlt">eddies</span> on the prokaryotic community was more apparent, as indicated by the higher PA, PHA, fraction of living cells, and percentage of active cells incorporating leucine within <span class="hlt">eddies</span> than at FF stations. Prokaryotic community composition differed also between <span class="hlt">eddy</span> and FF stations in the epipelagic layer. In the mesopelagic layer (200-1000 m), there were also significant differences in PA and PHA between <span class="hlt">eddy</span> and FF stations, although in general, there were no clear differences in community composition or single-cell activity. The effects on prokaryotic activity and community structure were stronger in AE than CE, decreasing with depth in both types of <span class="hlt">eddies</span>. Overall, both types of <span class="hlt">eddies</span> show distinct community compositions (as compared with FF in the epipelagic), and represent oceanic 'hotspots' of prokaryotic activity (in the epi- and mesopelagic realms).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPC14D2096T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPC14D2096T"><span>Birth, life and death of an Anticyclonic <span class="hlt">eddy</span> in the Southern Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Torres, R.; Sallee, J. B.; Schwarz, J.; Hosegood, P. J.; Taylor, J. R.; Adams, K.; Bachman, S.; Stamper, M. A.</p> <p>2016-02-01</p> <p>The Antarctic Circumpolar Current (ACC) is a climatically relevant frontal structure of global importance, which regularly develops instabilities growing into meanders, and eventually evolving into long-lived anticyclonic <span class="hlt">eddies</span>. These <span class="hlt">eddies</span> exhibit sustained primary productivity that can last several months fuelled by local resupply of nutrients. During April-May 2015 we conducted an intensive field experiment in the Southern Ocean where we sampled and tracked an ACC meander as it developed into an <span class="hlt">eddy</span> and later vanished some 90 days later. The physical characteristics of the meander and <span class="hlt">eddy</span> were observed with a combination of high resolution hydrography, ADCP and turbulence observations, in addition to biogeochemical observations of nutrients and phytoplankton. The life and death of the <span class="hlt">eddy</span> was subsequently tracked through Argo, BIO-Argo Lagrangian profilers and remote sensing. In this presentation we will use observations and ecosystem modelling to discuss the physical processes that sustain the observed high Chlorophyll levels in the <span class="hlt">eddy</span> and explore how the <span class="hlt">eddy</span> evolution impacts the rate of nutrient supply and how this translates into the observed changes in chlorophyll. We will discuss the relevance of <span class="hlt">eddy</span> formation to Chlorophyll and productivity in the region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050061082','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050061082"><span>Study of Near-Surface Models in Large-<span class="hlt">Eddy</span> Simulations of a Neutrally Stratified Atmospheric Boundary Layer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Senocak, I.; Ackerman, A. S.; Kirkpatrick, M. P.; Stevens, D. E.; Mansour, N. N.</p> <p>2004-01-01</p> <p>Large-<span class="hlt">eddy</span> simulation (LES) is a widely used <span class="hlt">technique</span> in armospheric modeling research. In LES, large, unsteady, three dimensional structures are resolved and small structures that are not resolved on the computational grid are modeled. A filtering operation is applied to distinguish between resolved and unresolved scales. We present two near-surface models that have found use in atmospheric modeling. We also suggest a simpler <span class="hlt">eddy</span> viscosity model that adopts Prandtl's mixing length model (Prandtl 1925) in the vicinity of the surface and blends with the dynamic Smagotinsky model (Germano et al, 1991) away from the surface. We evaluate the performance of these surface models by simulating a neutraly stratified atmospheric boundary layer.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19870036447&hterms=value+biological&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dvalue%2Bbiological','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19870036447&hterms=value+biological&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dvalue%2Bbiological"><span>Biological consequences of a recurrent <span class="hlt">eddy</span> off Point Conception, California</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Haury, Loren R.; Simpson, James J.; Pelaez, Jose; Wisenhahn, David; Koblinsky, Chester J.</p> <p>1986-01-01</p> <p>The biological effects on three different time scales (100-day mesoscale, annual, and several-year) of a mesoscale anticyclonic <span class="hlt">eddy</span> consistently found in shipboard surveys and satellite-sensed data several hundred kilometers southwest of Point Conception, CA, are described. A detailed shipboard study of the <span class="hlt">eddy</span> in January 1981 found a complex system of fronts in surface chlorophyll at the northern edge of the <span class="hlt">eddy</span>; microplankton and zooplankton distributions were strongly affected by entrainment processes at the surface and, apparently, at depth. Concurrent satellite coastal zone color scanner ocean color images show agreement with the general surface characteristics of the <span class="hlt">eddy</span> chlorophyll field but do not reflect features deeper than about 25 m, including the contribution of the deep chlorophyll maximum to the integrated chlorophyll values. Satellite data for the period October 1980 through October 1981 and shipboard data from California Cooperative Oceanic Fisheries Investigations (CalCOFI) for December 1980 to July 1981 show the continued presence of the <span class="hlt">eddy</span> in the sea surface temperature and color field and in the distributions of surface chlorophyll and zooplankton displacement volume. A review of the CalCOFI survey results from 1949 to the present time demonstrates the recurrent nature of the <span class="hlt">eddy</span> system on a year-to-year basis. The <span class="hlt">eddy</span> system appears to have a significant effect on the distribution of both oceanic and nearshore organisms. Offshore transport of coastal species occurs in the form of large entrained plumes or filaments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/13257','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/13257"><span>Development of and Improved Magneto-Optic/<span class="hlt">Eddy</span>-Current Imager</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>1997-04-01</p> <p>Magneto-optic/<span class="hlt">eddy</span>-current imaging technology has been developed and approved for inspection of cracks in aging aircraft. This relatively new nondestructive test method gives the inspector the ability to quickly generate real-time <span class="hlt">eddy</span>-current images...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20120007524','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20120007524"><span><span class="hlt">Eddy</span> Current System and Method for Crack Detection</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wincheski, Russell A. (Inventor); Simpson, John W. (Inventor)</p> <p>2012-01-01</p> <p>An <span class="hlt">eddy</span> current system and method enables detection of sub-surface damage in a cylindrical object. The invention incorporates a dual frequency, orthogonally wound <span class="hlt">eddy</span> current probe mounted on a stepper motor-controlled scanning system. The system is designed to inspect for outer surface damage from the interior of the cylindrical object.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1992MatEv..50.1225H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1992MatEv..50.1225H"><span><span class="hlt">Eddy</span> current standards - Cracks versus notches</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hagemaier, D. J.; Collingwood, M. R.; Nguyen, K. H.</p> <p>1992-10-01</p> <p><span class="hlt">Eddy</span> current tests aimed at evaluating cracks and electron-discharge machined (EDM) notches in 7075-T6 aluminum specimens are described. A comparison of the shape and amplitude of recordings made from both transverse and longitudinal scans of small EDM notches and fatigue cracks showd almost identical results. The signal amplitude and phase angle increased with an increase of EDM notch and crak size. It is concluded that equivalent <span class="hlt">eddy</span> current results obtained from similar-size surface cracks and notches in aluminum can be used to establish a desired sensitivity level for inspection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000RScI...71..567B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000RScI...71..567B"><span><span class="hlt">Eddy</span> current testing probe with dual half-cylindrical coils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bae, Byung-Hoon; Choi, Jung-Mi; Kim, Soo-Yong</p> <p>2000-02-01</p> <p>We have developed a new <span class="hlt">eddy</span> current probe composed of a dual half-cylindrical (2HC) coil as an exciting coil and a sensing coil that is placed in the small gap of the 2HC coil. The 2HC coil induces a linear <span class="hlt">eddy</span> current on the narrow region within the target medium. The magnitude of <span class="hlt">eddy</span> current has a maximum peak with the narrow width, underneath the center of the exciting 2HC coil. Because of the linear <span class="hlt">eddy</span> current, the probe can be used to detect not only the existence of a crack but also its direction in conducting materials. Using specimen with a machined crack, and varying the exciting frequency from 0.5 to 100 kHz, we investigated the relationships between the direction of crack and the output voltage of the sensing coil.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRC..123..201C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRC..123..201C"><span>Mesoscale <span class="hlt">Eddy</span> Activity and Transport in the Atlantic Water Inflow Region North of Svalbard</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Crews, L.; Sundfjord, A.; Albretsen, J.; Hattermann, T.</p> <p>2018-01-01</p> <p>Mesoscale <span class="hlt">eddies</span> are known to transport heat and biogeochemical properties from Arctic Ocean boundary currents to basin interiors. Previous hydrographic surveys and model results suggest that <span class="hlt">eddy</span> formation may be common in the Atlantic Water (AW) inflow area north of Svalbard, but no quantitative <span class="hlt">eddy</span> survey has yet been done for the region. Here vorticity and water property signatures are used to identify and track AW <span class="hlt">eddies</span> in an <span class="hlt">eddy</span>-resolving sea ice-ocean model. The boundary current sheds AW <span class="hlt">eddies</span> along most of the length of the continental slope considered, from the western Yermak Plateau to 40°E, though <span class="hlt">eddies</span> forming east of 20°E are likely more important for slope-to-basin transport. <span class="hlt">Eddy</span> formation seasonality reflects seasonal stability properties of the boundary current in the eastern portion of the study domain, but on and immediately east of the Yermak Plateau enhanced <span class="hlt">eddy</span> formation during summer merits further investigation. AW <span class="hlt">eddies</span> tend to be anticyclonic, have radii close to the local deformation radius, and be centered in the halocline. They transport roughly 0.16 Sv of AW and, due to their warm cores, 1.0 TW away from the boundary current. These findings suggest <span class="hlt">eddies</span> may be important for halocline ventilation in the Eurasian Basin, as has been shown for Pacific Water <span class="hlt">eddies</span> in the Canadian Basin.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4095903','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4095903"><span>The prospect of using large <span class="hlt">eddy</span> and detached <span class="hlt">eddy</span> simulations in engineering design, and the research required to get there</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Larsson, Johan; Wang, Qiqi</p> <p>2014-01-01</p> <p>In this paper, we try to look into the future to envision how large <span class="hlt">eddy</span> and detached <span class="hlt">eddy</span> simulations will be used in the engineering design process about 20–30 years from now. Some key challenges specific to the engineering design process are identified, and some of the critical outstanding problems and promising research directions are discussed. PMID:25024421</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20080009563','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20080009563"><span><span class="hlt">Eddy</span> Current COPV Overwrap and Liner Thickness Measurement System and Data Analysis for 40-Inch Kevlar COPVs SN002 and SN027</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wincheski, Russell A.</p> <p>2008-01-01</p> <p>As part of the health assessment of flight spare 40in diameter Kevlar composite overwrapped pressure vessels (COPVs) SN002 and SN027 an <span class="hlt">eddy</span> current characterization of the composite and liner thickness change during pressurization was requested under WSTF-TP-1085-07.A, "Space Shuttle Orbiter Main Propulsion System P/N MC282-0082-0101 S/N 002 and Orbital Maneuvering System P/N MC282-0082-001 S/N 027 COPV Health Assessment." The through the thickness strains have been determined to be an important parameter in the analysis of the reliability and likelihood of stress rupture failure. <span class="hlt">Eddy</span> current <span class="hlt">techniques</span> provide a means to measure these thicknesses changes based upon the change in impedance of an <span class="hlt">eddy</span> current sensor mounted on the exterior of the vessel. Careful probe and <span class="hlt">technique</span> design have resulted in the capability to independently measure the liner and overwrap thickness changes to better than +/- 0.0005 in. at each sensor location. Descriptions of the inspection system and test results are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70023165','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70023165"><span>Multispectral image sharpening using wavelet transform <span class="hlt">techniques</span> and spatial <span class="hlt">correlation</span> of edges</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Lemeshewsky, George P.; Schowengerdt, Robert A.</p> <p>2000-01-01</p> <p>Several reported image fusion or sharpening <span class="hlt">techniques</span> are based on the discrete wavelet transform (DWT). The <span class="hlt">technique</span> described here uses a pixel-based maximum selection rule to combine respective transform coefficients of lower spatial resolution near-infrared (NIR) and higher spatial resolution panchromatic (pan) imagery to produce a sharpened NIR image. Sharpening assumes a radiometric <span class="hlt">correlation</span> between the spectral band images. However, there can be poor <span class="hlt">correlation</span>, including edge contrast reversals (e.g., at soil-vegetation boundaries), between the fused images and, consequently, degraded performance. To improve sharpening, a local area-based <span class="hlt">correlation</span> <span class="hlt">technique</span> originally reported for edge comparison with image pyramid fusion is modified for application with the DWT process. Further improvements are obtained by using redundant, shift-invariant implementation of the DWT. Example images demonstrate the improvements in NIR image sharpening with higher resolution pan imagery.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018PhPl...25e5707M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018PhPl...25e5707M"><span>A <span class="hlt">technique</span> for plasma velocity-space cross-<span class="hlt">correlation</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mattingly, Sean; Skiff, Fred</p> <p>2018-05-01</p> <p>An advance in experimental plasma diagnostics is presented and used to make the first measurement of a plasma velocity-space cross-<span class="hlt">correlation</span> matrix. The velocity space <span class="hlt">correlation</span> function can detect collective fluctuations of plasmas through a localized measurement. An empirical decomposition, singular value decomposition, is applied to this Hermitian matrix in order to obtain the plasma fluctuation eigenmode structure on the ion distribution function. A basic theory is introduced and compared to the modes obtained by the experiment. A full characterization of these modes is left for future work, but an outline of this endeavor is provided. Finally, the requirements for this experimental <span class="hlt">technique</span> in other plasma regimes are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5024127','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5024127"><span><span class="hlt">Eddy</span>, drift wave and zonal flow dynamics in a linear magnetized plasma</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Arakawa, H.; Inagaki, S.; Sasaki, M.; Kosuga, Y.; Kobayashi, T.; Kasuya, N.; Nagashima, Y.; Yamada, T.; Lesur, M.; Fujisawa, A.; Itoh, K.; Itoh, S.-I.</p> <p>2016-01-01</p> <p>Turbulence and its structure formation are universal in neutral fluids and in plasmas. Turbulence annihilates global structures but can organize flows and <span class="hlt">eddies</span>. The mutual-interactions between flow and the <span class="hlt">eddy</span> give basic insights into the understanding of non-equilibrium and nonlinear interaction by turbulence. In fusion plasma, clarifying structure formation by Drift-wave turbulence, driven by density gradients in magnetized plasma, is an important issue. Here, a new mutual-interaction among <span class="hlt">eddy</span>, drift wave and flow in magnetized plasma is discovered. A two-dimensional solitary <span class="hlt">eddy</span>, which is a perturbation with circumnavigating motion localized radially and azimuthally, is transiently organized in a drift wave – zonal flow (azimuthally symmetric band-like shear flows) system. The excitation of the <span class="hlt">eddy</span> is synchronized with zonal perturbation. The organization of the <span class="hlt">eddy</span> has substantial impact on the acceleration of zonal flow. PMID:27628894</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..44.3255D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..44.3255D"><span>Observational insights into chlorophyll distributions of subtropical South Indian Ocean <span class="hlt">eddies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dufois, François; Hardman-Mountford, Nick J.; Fernandes, Michelle; Wojtasiewicz, Bozena; Shenoy, Damodar; Slawinski, Dirk; Gauns, Mangesh; Greenwood, Jim; Toresen, Reidar</p> <p>2017-04-01</p> <p>The South Indian Ocean subtropical gyre has been described as a unique environment where anticyclonic ocean <span class="hlt">eddies</span> highlight enhanced surface chlorophyll in winter. The processes responsible for this chlorophyll increase in anticyclones have remained elusive, primarily because previous studies investigating this unusual behavior were mostly based on satellite data, which only views the ocean surface. Here we present in situ data from an oceanographic voyage focusing on the mesoscale variability of biogeochemical variables across the subtropical gyre. During this voyage an autonomous biogeochemical profiling float transected an anticyclonic <span class="hlt">eddy</span>, recording its physical and biological state over a period of 6 weeks. We show that several processes might be responsible for the <span class="hlt">eddy</span>/chlorophyll relationship, including horizontal advection of productive waters and deeper convective mixing in anticyclonic <span class="hlt">eddies</span>. While a deep chlorophyll maximum is present in the subtropical Indian Ocean outside anticyclonic <span class="hlt">eddies</span>, mixing reaches deeper in anticyclonic <span class="hlt">eddy</span> cores, resulting in increased surface chlorophyll due to the stirring of the deep chlorophyll maximum and possibly resulting in new production from nitrate injection below the deep chlorophyll maximum.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_14");'>14</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li class="active"><span>16</span></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_16 --> <div id="page_17" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="321"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/11046509','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/11046509"><span>Time evolution of the <span class="hlt">eddy</span> viscosity in two-dimensional navier-stokes flow</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Chaves; Gama</p> <p>2000-02-01</p> <p>The time evolution of the <span class="hlt">eddy</span> viscosity associated with an unforced two-dimensional incompressible Navier-Stokes flow is analyzed by direct numerical simulation. The initial condition is such that the <span class="hlt">eddy</span> viscosity is isotropic and negative. It is shown by concrete examples that the Navier-Stokes dynamics stabilizes negative <span class="hlt">eddy</span> viscosity effects. In other words, this dynamics moves monotonically the initial negative <span class="hlt">eddy</span> viscosity to positive values before relaxation due to viscous term occurs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008GMS...177.....H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008GMS...177.....H"><span>Ocean Modeling in an <span class="hlt">Eddying</span> Regime</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hecht, Matthew W.; Hasumi, Hiroyasu</p> <p></p> <p>This monograph is the first to survey progress in realistic simulation in a strongly <span class="hlt">eddying</span> regime made possible by recent increases in computational capability. Its contributors comprise the leading researchers in this important and constantly evolving field. Divided into three parts, • Oceanographic Processes and Regimes: Fundamental Questions • Ocean Dynamics and State: From Regional to Global Scale, and • Modeling at the Mesoscale: State of the Art and Future Directions the volume details important advances in physical oceanography based on <span class="hlt">eddy</span> resolving ocean modeling. It captures the state of the art and discusses issues that ocean modelers must consider in order to effectively contribute to advancing current knowledge, from subtleties of the underlying fluid dynamical equations to meaningful comparison with oceanographic observations and leading-edge model development. It summarizes many of the important results which have emerged from ocean modeling in an <span class="hlt">eddying</span> regime, for those interested broadly in the physical science. More technical topics are intended to address the concerns of those actively working in the field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A41B2267H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A41B2267H"><span>Annular Mode Dynamics: <span class="hlt">Eddy</span> Feedbacks and the Underlying Mechanisms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hassanzadeh, P.; Ma, D.; Kuang, Z.</p> <p>2017-12-01</p> <p>Annular modes are the leading modes the extratropical circulation variability in both hemispheres on intraseasonal to interannual timescales. Temporal persistence and an equivalent-barotropic dipolar wind anomaly are the key spatio-temporal characteristics of the annular modes. The potential source(s) of this persistence, and in particular, whether there is a contribution from a positive <span class="hlt">eddy</span>-jet feedback, are still unclear (e.g., Lorenz and Hartmann, 2001; Byrne et al., 2016). The mechanism of this feedback, and how it depends on processes such as surface friction, is also not well understood (e.g., Robinson, 2000; Gerber et al., 2007). In this study, we utilize the recently calculated Linear Response Function (LRF) of an idealized GCM (Hassanzadeh and Kuang, 2016). The LRF enables us to accurately calculate the response of <span class="hlt">eddy</span> momentum/heat fluxes to the zonal-mean zonal wind and temperature anomalies of the annular mode. Using this information: 1) We confirm the existence of a positive <span class="hlt">eddy</span>-jet feedback in the annular mode of the idealized GCM and accurately quantify the magnitude of this feedback; 2) We quantify the contribution of key processes (e.g., <span class="hlt">eddy</span> momentum/heat fluxes and surface friction) to the annular mode dynamics in the idealized GCM. We show that as proposed by Robinson (2000), the baroclinic component of the annular mode and surface friction are essential for the positive <span class="hlt">eddy</span>-jet feedback. Results show that this feedback increases the persistence of the annular mode by a factor of two. We also show that the barotropic component of the annular mode alone does not lead to persistence. In fact, the <span class="hlt">eddy</span>-jet feedback for the barotropic component is negative because of the dominance of the barotropic governor effect. 3) Using the results of 1, we evaluate the underlying assumptions and accuracy of the statistical methods previously developed for quantifying the <span class="hlt">eddy</span>-jet feedback (Lorenz and Hartmann, 2001; Simpson et al., 2013) and introduce a new</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.S43A4528W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.S43A4528W"><span>Pre-Processing and Cross-<span class="hlt">Correlation</span> <span class="hlt">Techniques</span> for Time-Distance Helioseismology</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, N.; de Ridder, S.; Zhao, J.</p> <p>2014-12-01</p> <p>In chaotic wave fields excited by a random distribution of noise sources a cross-<span class="hlt">correlation</span> of the recordings made at two stations yield the interstation wave-field response. After early successes in helioseismology, laboratory studies and earth-seismology, this <span class="hlt">technique</span> found broad application in global and regional seismology. This development came with an increasing understanding of pre-processing and cross-<span class="hlt">correlation</span> workflows to yield an optimal signal-to-noise ratio (SNR). Helioseismologist rely heavily on stacking to increase the SNR. Until now, they have not studied different spectral-whitening and cross-<span class="hlt">correlation</span> workflows and relies heavily on stacking to increase the SNR. The recordings vary considerably between sunspots and regular portions of the sun. Within the sunspot the periodic effects of the observation satellite orbit are difficult to remove. We remove a running alpha-mean from the data and apply a soft clip to deal with data glitches. The recordings contain energy of both flow and waves. A frequency domain filter selects the wave energy. Then the data is input to several pre-processing and cross-<span class="hlt">correlation</span> <span class="hlt">techniques</span>, common to earth seismology. We anticipate that spectral whitening will flatten the energy spectrum of the cross-<span class="hlt">correlations</span>. We also expect that the cross-<span class="hlt">correlations</span> converge faster to their expected value when the data is processed over overlapping windows. The result of this study are expected to aid in decreasing the stacking while maintaining good SNR.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2007AGUSMOS53A..15Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2007AGUSMOS53A..15Z"><span>The Death of Two <span class="hlt">Eddies</span>, Against the Shelf</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zavala-Trujillo, B.; Badan, A.; Rivas, D.; Ochoa, J.; Sheinbaum, J.; Candela, J.</p> <p>2007-05-01</p> <p>A set of five moorings deployed in front of the coast of Tamaulipas, western Gulf of Mexico, provided fourteen months (from August 2004 to November 2005) of surface to bottom observations of currents and temperature that document the processes associated with the collision and dissipation of two warm mesoscale <span class="hlt">eddies</span> with the continental slope. Two Loop Current <span class="hlt">eddies</span> (Titanic and Ulysses) were identified reaching the study area during the observation period. On September 2004, the two southernmost 2000-m moorings show that temperature and salinity increases throughout the entire water column, related to <span class="hlt">eddy</span> Titanic; similarily; on April 2005, <span class="hlt">eddy</span> Ulysses caused a strong increase of temperature in the 3500-m mooring. The velocity field suggests three different régimes: a coastal region, the continental slope currents, and the abyssal circulation. Over the slope, three different layers can be identified: a surface layer (above 500 m depth), influenced by <span class="hlt">eddies</span> and transients, a deep layer (under de 1900 m) with a persistent southerly current and a transition layer (from 500 to 1900 m) that separates them. The variance ellipses at ~ 700 m at the 3500-m mooring have no a predominant orientation of the mayor axis. At the northernmost 2000-m mooring, the axis of maximum variation is oriented with the bathymetry, but at the southernmost 2000-m mooring it is perpendicular to the coast. The spectral characteristics of the measurements are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20888278','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20888278"><span><span class="hlt">Eddy</span> current simulation in thick cylinders of finite length induced by coils of arbitrary geometry.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Sanchez Lopez, Hector; Poole, Michael; Crozier, Stuart</p> <p>2010-12-01</p> <p><span class="hlt">Eddy</span> currents are inevitably induced when time-varying magnetic field gradients interact with the metallic structures of a magnetic resonance imaging (MRI) scanner. The secondary magnetic field produced by this induced current degrades the spatial and temporal performance of the primary field generated by the gradient coils. Although this undesired effect can be minimized by using actively and/or passively shielded gradient coils and current pre-emphasis <span class="hlt">techniques</span>, a residual <span class="hlt">eddy</span> current still remains in the MRI scanner structure. Accurate simulation of these <span class="hlt">eddy</span> currents is important in the successful design of gradient coils and magnet cryostat vessels. Efficient methods for simulating <span class="hlt">eddy</span> currents are currently restricted to cylindrical-symmetry. The approach presented in this paper divides thick conducting cylinders into thin layers (thinner than the skin depth) and expresses the current density on each as a Fourier series. The coupling between each mode of the Fourier series with every other is modeled with an inductive network method. In this way, the <span class="hlt">eddy</span> currents induced in realistic cryostat surfaces by coils of arbitrary geometry can be simulated. The new method was validated by simulating a canonical problem and comparing the results against a commercially available software package. An accurate skin depth of 2.76 mm was calculated in 6 min with the new method. The currents induced by an actively shielded x-gradient coil were simulated assuming a finite length cylindrical cryostat consisting of three different conducting materials. Details of the temporal-spatial induced current diffusion process were simulated through all cryostat layers, which could not be efficiently simulated with any other method. With this data, all quantities that depend on the current density, such as the secondary magnetic field, are simply evaluated. Copyright © 2010 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRD..11516202C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRD..11516202C"><span>Deposition velocity of ultrafine particles measured with the <span class="hlt">Eddy-Correlation</span> Method over the Nansen Ice Sheet (Antarctica)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Contini, D.; Donateo, A.; Belosi, F.; Grasso, F. M.; Santachiara, G.; Prodi, F.</p> <p>2010-08-01</p> <p>This work reports an analysis of the concentration, size distribution, and deposition velocity of atmospheric particles over snow and iced surfaces on the Nansen Ice Sheet (Antarctica). Measurements were performed using the <span class="hlt">eddy-correlation</span> method at a remote site during the XXII Italian expedition of the National Research Program in Antarctica (PNRA) in 2006. The measurement system was based on a condensation particle counter (CPC) able to measure particles down to 9 nm in diameter with a 50% efficiency and a Differential Mobility Particle Sizer for evaluating particle size distributions from 11 to 521 nm diameter in 39 channels. A method based on postprocessing with digital filters was developed to take into account the effect of the slow time response of the CPC. The average number concentration was 1338 cm-3 (median, 978 cm-3; interquartile range, 435-1854 cm-3). Higher concentrations were observed at low wind velocities. Results gave an average deposition velocity of 0.47 mm/s (median, 0.19 mm/s; interquartile range, -0.21 -0.88 mm/s). Deposition increased with the friction velocity and was on average 0.86 mm/s during katabatic wind characterized by velocities higher than 4 m/s. Observed size distributions generally presented two distinct modes, the first at approximately 15-20 nm and the second (representing on average 70% of the total particles) at 60-70 nm. Under strong-wind conditions, the second mode dominated the average size distribution.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26328583','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26328583"><span>Dissipative inertial transport patterns near coherent Lagrangian <span class="hlt">eddies</span> in the ocean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Beron-Vera, Francisco J; Olascoaga, María J; Haller, George; Farazmand, Mohammad; Triñanes, Joaquín; Wang, Yan</p> <p>2015-08-01</p> <p>Recent developments in dynamical systems theory have revealed long-lived and coherent Lagrangian (i.e., material) <span class="hlt">eddies</span> in incompressible, satellite-derived surface ocean velocity fields. Paradoxically, observed drifting buoys and floating matter tend to create dissipative-looking patterns near oceanic <span class="hlt">eddies</span>, which appear to be inconsistent with the conservative fluid particle patterns created by coherent Lagrangian <span class="hlt">eddies</span>. Here, we show that inclusion of inertial effects (i.e., those produced by the buoyancy and size finiteness of an object) in a rotating two-dimensional incompressible flow context resolves this paradox. Specifically, we obtain that anticyclonic coherent Lagrangian <span class="hlt">eddies</span> attract (repel) negatively (positively) buoyant finite-size particles, while cyclonic coherent Lagrangian <span class="hlt">eddies</span> attract (repel) positively (negatively) buoyant finite-size particles. We show how these results explain dissipative-looking satellite-tracked surface drifter and subsurface float trajectories, as well as satellite-derived Sargassum distributions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19163660','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19163660"><span>The numeric calculation of <span class="hlt">eddy</span> current distributions in transcranial magnetic stimulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Tsuyama, Seichi; Hyodo, Akira; Sekino, Masaki; Hayami, Takehito; Ueno, Shoogo; Iramina, Keiji</p> <p>2008-01-01</p> <p>Transcranial magnetic stimulation (TMS) is a method to stimulate neurons in the brain. It is necessary to obtain <span class="hlt">eddy</span> current distributions and determine parameters such as position, radius and bend-angle of the coil to stimulate target area exactly. In this study, we performed FEM-based numerical simulations of <span class="hlt">eddy</span> current induced by TMS using three-dimentional human head model with inhomogeneous conductivity. We used double-cone coil and changed the coil radius and bend-angle of coil. The result of computer simulation showed that as coil radius increases, the <span class="hlt">eddy</span> current became stronger everywhere. And coil with bend-angle of 22.5 degrees induced stronger <span class="hlt">eddy</span> current than the coil with bendangle of 0 degrees. Meanwhile, when the bend-angle was 45 degrees, <span class="hlt">eddy</span> current became weaker than these two cases. This simulation allowed us to determine appropriate parameter easier.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO21A..06B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO21A..06B"><span>Inference and Biogeochemical Response of Vertical Velocities inside a Mode Water <span class="hlt">Eddy</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Barceló-Llull, B.; Pallas Sanz, E.; Sangrà, P.</p> <p>2016-02-01</p> <p>With the aim to study the modulation of the biogeochemical fluxes by the ageostrophic secondary circulation in anticyclonic mesoscale <span class="hlt">eddies</span>, a typical <span class="hlt">eddy</span> of the Canary <span class="hlt">Eddy</span> Corridor was interdisciplinary surveyed on September 2014 in the framework of the PUMP project. The <span class="hlt">eddy</span> was elliptical shaped, 4 month old, 110 km diameter and 400 m depth. It was an intrathermocline type often also referred as mode water <span class="hlt">eddy</span> type. We inferred the mesoscale vertical velocity field resolving a generalized omega equation from the 3D density and ADCP velocity fields of a five-day sampled CTD-SeaSoar regular grid centred on the <span class="hlt">eddy</span>. The grid transects where 10 nautical miles apart. Although complex, in average, the inferred omega velocity field (hereafter w) shows a dipolar structure with downwelling velocities upstream of the propagation path (west) and upwelling velocities downstream. The w at the <span class="hlt">eddy</span> center was zero and maximum values were located at the periphery attaining ca. 6 m day-1. Coinciding with the occurrence of the vertical velocities cells a noticeable enhancement of phytoplankton biomass was observed at the <span class="hlt">eddy</span> periphery respect to the far field. A corresponding upward diapycnal flux of nutrients was also observed at the periphery. As minimum velocities where reached at the <span class="hlt">eddy</span> center, lineal Ekman pumping mechanism was discarded. Minimum values of phytoplankton biomass where also observed at the <span class="hlt">eddy</span> center. The possible mechanisms for such dipolar w cell are still being investigated, but an analysis of the generalized omega equation forcing terms suggest that it may be a combination of horizontal deformation and advection of vorticity by the ageostrophic current (related to nonlinear Ekman pumping). As expected for Trades, the wind was rather constant and uniform with a speed of ca. 5 m s-1. Diagnosed nonlinear Ekman pumping leaded also to a dipolar cell that mirrors the omega w dipolar cell.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19940000548&hterms=food+beverage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfood%2Bbeverage','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19940000548&hterms=food+beverage&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dfood%2Bbeverage"><span><span class="hlt">Eddy</span>-Current Inspection Of Tab Seals On Beverage Cans</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bar-Cohen, Yoseph</p> <p>1994-01-01</p> <p><span class="hlt">Eddy</span>-current inspection system monitors tab seals on beverage cans. Device inspects all cans at usual production rate of 1,500 to 2,000 cans per minute. Automated inspection of all units replaces visual inspection by microscope aided by mass spectrometry. System detects defects in real time. Sealed cans on conveyor pass near one of two coils in differential <span class="hlt">eddy</span>-current probe. Other coil in differential <span class="hlt">eddy</span>-current probe positioned near stationary reference can on which tab seal is known to be of acceptable quality. Signal of certain magnitude at output of probe indicates defective can, automatically ejected from conveyor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS43B1278F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS43B1278F"><span>Deep <span class="hlt">Eddies</span> in the Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Furey, H. H.; Bower, A. S.; Perez-Brunius, P.; Hamilton, P.</p> <p>2014-12-01</p> <p>A major Lagrangian program is currently underway to map the deep (1500-2500 m) circulation of the entire Gulf of Mexico. Beginning in 2011, more than 120 acoustically tracked RAFOS floats have been released in the eastern, central and western Gulf, many in pairs and triplets. Most floats are programmed to drift for two years, obtaining position fixes and temperature/pressure measurements three times daily. More than 80 floats have completed their missions, and results from the trajectories will be described with a focus on mesoscale <span class="hlt">eddying</span> behavior. In particular, the first-ever observations of deep energetic anticyclonic <span class="hlt">eddies</span> (possibly lenses) forming at and separating from a northeastward-flowing boundary current west of Campeche Bank will be discussed. The existence of these <span class="hlt">eddies</span> has major implications for exchange between the continental slope and interior Gulf. The project is being supported by the U.S. Bureau of Ocean Energy Management (BOEM).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19980237753','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19980237753"><span>Non-Contact <span class="hlt">EDDY</span> Current Hole Eccentricity and Diameter Measurement</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chern, E. James</p> <p>1998-01-01</p> <p>Precision holes are among the most critical features of a mechanical component. Deviations from permissible tolerances can impede operation and result in unexpected failure. We have developed an automated non-contact <span class="hlt">eddy</span> current hole diameter and eccentricity measuring system. The operating principle is based on the <span class="hlt">eddy</span> current lift-off effect, which is the coil impedance as a function of the distance between the coil and the test object. An absolute <span class="hlt">eddy</span> current probe rotates in the hole. The impedance of each angular position is acquired and input to the computer for integration and analysis. The eccentricity of the hole is the profile of the impedance as a function of angular position as compared to a straight line, an ideal hole. The diameter of the hole is the sum of the diameter of the probe and twice the distance-calibrated impedance. An <span class="hlt">eddy</span> current image is generated by integrating angular scans for a plurality of depths between the top and bottom to display the eccentricity profile. This system can also detect and image defects in the hole. The method for non-contact <span class="hlt">eddy</span> current hole diameter and eccentricity measurement has been granted a patent by the U.S. Patent and Trademark Office.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19930035611&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DEddy%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19930035611&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DEddy%2Bcurrent"><span><span class="hlt">Eddy</span> current inspection of weld defects in tubing</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Katragadda, G.; Lord, W.</p> <p>1992-01-01</p> <p>An approach using differential probes for the inspection of weld defects in tubing is studied. Finite element analysis is used to model the weld regions and defects. Impedance plane signals are predicted for different weld defect types and compared wherever possible with signals from actual welds in tubing. Results show that detection and sizing of defects in tubing is possible using differential <span class="hlt">eddy</span> current <span class="hlt">techniques</span>. The phase angle of the impedance plane trajectory gives a good indication of the sizing of the crack. Data on the type of defect can be obtained from the shape of the impedance plane trajectory and the phase. Depending on the skin depth, detection of outer wall, inner wall, and subsurface defects is possible.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1047962-large-eddy-simulation-wind-plant-aerodynamics','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1047962-large-eddy-simulation-wind-plant-aerodynamics"><span>Large-<span class="hlt">Eddy</span> Simulation of Wind-Plant Aerodynamics</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Churchfield, M. J.; Lee, S.; Moriarty, P. J.</p> <p></p> <p>In this work, we present results of a large-<span class="hlt">eddy</span> simulation of the 48 multi-megawatt turbines composing the Lillgrund wind plant. Turbulent inflow wind is created by performing an atmospheric boundary layer precursor simulation, and turbines are modeled using a rotating, variable-speed actuator line representation. The motivation for this work is that few others have done large-<span class="hlt">eddy</span> simulations of wind plants with a substantial number of turbines, and the methods for carrying out the simulations are varied. We wish to draw upon the strengths of the existing simulations and our growing atmospheric large-<span class="hlt">eddy</span> simulation capability to create a sound methodology formore » performing this type of simulation. We used the OpenFOAM CFD toolbox to create our solver. The simulated time-averaged power production of the turbines in the plant agrees well with field observations, except with the sixth turbine and beyond in each wind-aligned. The power produced by each of those turbines is overpredicted by 25-40%. A direct comparison between simulated and field data is difficult because we simulate one wind direction with a speed and turbulence intensity characteristic of Lillgrund, but the field observations were taken over a year of varying conditions. The simulation shows the significant 60-70% decrease in the performance of the turbines behind the front row in this plant that has a spacing of 4.3 rotor diameters in this direction. The overall plant efficiency is well predicted. This work shows the importance of using local grid refinement to simultaneously capture the meter-scale details of the turbine wake and the kilometer-scale turbulent atmospheric structures. Although this work illustrates the power of large-<span class="hlt">eddy</span> simulation in producing a time-accurate solution, it required about one million processor-hours, showing the significant cost of large-<span class="hlt">eddy</span> simulation.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=346189','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=346189"><span>Long-term observations of crop water use with <span class="hlt">eddy</span> covariance stations and coupling with crop simulation models</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Understanding crop water use is critical to being able to determine crop water requirements and when water is limiting crop productivity. There have been many different <span class="hlt">techniques</span> used to quantify crop water use and the <span class="hlt">eddy</span> covariance approach is one method that has the capacity to measure crop wat...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1033443','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1033443"><span>Large-<span class="hlt">Eddy</span> Simulation of Wind-Plant Aerodynamics: Preprint</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Churchfield, M. J.; Lee, S.; Moriarty, P. J.</p> <p></p> <p>In this work, we present results of a large-<span class="hlt">eddy</span> simulation of the 48 multi-megawatt turbines composing the Lillgrund wind plant. Turbulent inflow wind is created by performing an atmospheric boundary layer precursor simulation and turbines are modeled using a rotating, variable-speed actuator line representation. The motivation for this work is that few others have done wind plant large-<span class="hlt">eddy</span> simulations with a substantial number of turbines, and the methods for carrying out the simulations are varied. We wish to draw upon the strengths of the existing simulations and our growing atmospheric large-<span class="hlt">eddy</span> simulation capability to create a sound methodology for performingmore » this type of simulation. We have used the OpenFOAM CFD toolbox to create our solver.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhDT.........3G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhDT.........3G"><span>Large <span class="hlt">eddy</span> simulations of compressible magnetohydrodynamic turbulence</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grete, Philipp</p> <p>2017-02-01</p> <p>Supersonic, magnetohydrodynamic (MHD) turbulence is thought to play an important role in many processes - especially in astrophysics, where detailed three-dimensional observations are scarce. Simulations can partially fill this gap and help to understand these processes. However, direct simulations with realistic parameters are often not feasible. Consequently, large <span class="hlt">eddy</span> simulations (LES) have emerged as a viable alternative. In LES the overall complexity is reduced by simulating only large and intermediate scales directly. The smallest scales, usually referred to as subgrid-scales (SGS), are introduced to the simulation by means of an SGS model. Thus, the overall quality of an LES with respect to properly accounting for small-scale physics crucially depends on the quality of the SGS model. While there has been a lot of successful research on SGS models in the hydrodynamic regime for decades, SGS modeling in MHD is a rather recent topic, in particular, in the compressible regime. In this thesis, we derive and validate a new nonlinear MHD SGS model that explicitly takes compressibility effects into account. A filter is used to separate the large and intermediate scales, and it is thought to mimic finite resolution effects. In the derivation, we use a deconvolution approach on the filter kernel. With this approach, we are able to derive nonlinear closures for all SGS terms in MHD: the turbulent Reynolds and Maxwell stresses, and the turbulent electromotive force (EMF). We validate the new closures both a priori and a posteriori. In the a priori tests, we use high-resolution reference data of stationary, homogeneous, isotropic MHD turbulence to compare exact SGS quantities against predictions by the closures. The comparison includes, for example, <span class="hlt">correlations</span> of turbulent fluxes, the average dissipative behavior, and alignment of SGS vectors such as the EMF. In order to quantify the performance of the new nonlinear closure, this comparison is conducted from the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20040191710&hterms=mit&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmit','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20040191710&hterms=mit&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmit"><span>Subduction in an <span class="hlt">Eddy</span>-Resolving State Estimate of the Northeast Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gebbie, Geoffrey</p> <p>2004-01-01</p> <p>Are <span class="hlt">eddies</span> an important contributor to subduction in the eastern subtropical gyre? Here, an adjoint model is used to combine a regional, <span class="hlt">eddy</span>-resolving numerical model with observations to produce a state estimate of the ocean circulation. The estimate is a synthesis of a variety of in- situ observations from the Subduction Experiment, TOPEX/POSEIDON altimetry, and the MTI General Circulation Model. The adjoint method is successful because the Northeast Atlantic Ocean is only weakly nonlinear. The state estimate provides a physically-interpretable, <span class="hlt">eddy</span>-resolving information source to diagnose subduction. Estimates of <span class="hlt">eddy</span> subduction for the eastern subtropical gyre of the North Atlantic are larger than previously calculated from parameterizations in coarse-resolution models. Furthermore, <span class="hlt">eddy</span> subduction rates have typical magnitudes of 15% of the total subduction rate. <span class="hlt">Eddies</span> contribute as much as 1 Sverdrup to water-mass transformation, and hence subduction, in the North Equatorial Current and the Azores Current. The findings of this thesis imply that the inability to resolve or accurately parameterize <span class="hlt">eddy</span> subduction in climate models would lead to an accumulation of error in the structure of the main thermocline, even in the relatively-quiescent eastern subtropical gyre.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006BoLMe.120...39R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006BoLMe.120...39R"><span>Scalar Similarity for Relaxed <span class="hlt">Eddy</span> Accumulation Methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ruppert, Johannes; Thomas, Christoph; Foken, Thomas</p> <p>2006-07-01</p> <p>The relaxed <span class="hlt">eddy</span> accumulation (REA) method allows the measurement of trace gas fluxes when no fast sensors are available for <span class="hlt">eddy</span> covariance measurements. The flux parameterisation used in REA is based on the assumption of scalar similarity, i.e., similarity of the turbulent exchange of two scalar quantities. In this study changes in scalar similarity between carbon dioxide, sonic temperature and water vapour were assessed using scalar <span class="hlt">correlation</span> coefficients and spectral analysis. The influence on REA measurements was assessed by simulation. The evaluation is based on observations over grassland, irrigated cotton plantation and spruce forest. Scalar similarity between carbon dioxide, sonic temperature and water vapour showed a distinct diurnal pattern and change within the day. Poor scalar similarity was found to be linked to dissimilarities in the energy contained in the low frequency part of the turbulent spectra ( < 0.01 Hz). The simulations of REA showed significant change in b-factors throughout the diurnal course. The b-factor is part of the REA parameterisation scheme and describes a relation between the concentration difference and the vertical flux of a trace gas. The diurnal course of b-factors for carbon dioxide, sonic temperature and water vapour matched well. Relative flux errors induced in REA by varying scalar similarity were generally below ± 10%. Systematic underestimation of the flux of up to - 40% was found for the use of REA applying a hyperbolic deadband (HREA). This underestimation was related to poor scalar similarity between the scalar of interest and the scalar used as proxy for the deadband definition.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_15");'>15</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li class="active"><span>17</span></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_17 --> <div id="page_18" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="341"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/25938201','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/25938201"><span>Unsupervised classification of surface defects in wire rod production obtained by <span class="hlt">eddy</span> current sensors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Saludes-Rodil, Sergio; Baeyens, Enrique; Rodríguez-Juan, Carlos P</p> <p>2015-04-29</p> <p>An unsupervised approach to classify surface defects in wire rod manufacturing is developed in this paper. The defects are extracted from an <span class="hlt">eddy</span> current signal and classified using a clustering <span class="hlt">technique</span> that uses the dynamic time warping distance as the dissimilarity measure. The new approach has been successfully tested using industrial data. It is shown that it outperforms other classification alternatives, such as the modified Fourier descriptors.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUSMOS31C..03C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSMOS31C..03C"><span>Spatial-frequency variability of the <span class="hlt">eddy</span> kinetic energy in the South Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cecilio, C. M.; Gherardi, D. F.; Souza, R.; Correa-Ramirez, M.</p> <p>2013-05-01</p> <p>In the South Atlantic Ocean (SAO) part of the inter-oceanic flow is accomplished through the issuance of anticyclonic <span class="hlt">eddies</span> by the Agulhas Retroflection. This region, known as Agulhas Leakage (AL), is responsible by the intermittent shedding of <span class="hlt">eddies</span> in the SAO. The propagation of these <span class="hlt">eddies</span> into the SAO induces wave processes that allows the interaction between modes of variability of different basins, ranging from high to low frequency. Modelling studies suggests that the Indian-Atlantic inter-ocean exchange is strongly related to the structure of the wind field, in particular with the position of the maximum Southern Hemisphere westerly winds. This study aims to investigate the variations of the large-scale and regional mesoscale <span class="hlt">eddy</span> field over the SAO using a frequency domain <span class="hlt">technique</span>, Multiple Taper Method with Singular Value Decomposition (MTM-SVD). The MTM-SVD approach is applied to examine the individual and joint spatiotemporal variability modes of <span class="hlt">eddy</span> kinetic energy (EKE) and winds stress. The EKE is estimated from geostrophic velocity anomalies data distributed by Aviso and winds stress from winds dataset of Cross-Calibrated Multi-Platform (CCMP) project from PO.DAAC. The impact of the AL in the SAO, was assessed first for the entire region and subsequently applied in the regions of higher mesoscale activity, which are the Brazil-Malvinas Confluence (BMC), the AL, and the Brazilian Current (BC) region. The results of local fractional variance (LFV) of EKE obtained by the MTM-SVD method show a strong significant annual variability in SAO and BC region while in BMC and in AL this frequency is weaker. In the most energetic mesoscale activity regions (BMC and AL) the pattern of variability is distinct. In the BMC region the interannual variability is dominated while in the AL region the most part of variability is associated by high frequency. The joint LFV spectrum of wind and EKE show an out-of-phase relationship between the AL region and BMC region</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017PhFl...29h6601K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017PhFl...29h6601K"><span>Cycloidal meandering of a mesoscale anticyclonic <span class="hlt">eddy</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kizner, Ziv; Shteinbuch-Fridman, Biana; Makarov, Viacheslav; Rabinovich, Michael</p> <p>2017-08-01</p> <p>By applying a theoretical approach, we propose a hypothetical scenario that might explain some features of the movement of a long-lived mesoscale anticyclone observed during 1990 in the Bay of Biscay [R. D. Pingree and B. Le Cann, "Three anticyclonic slope water oceanic <span class="hlt">eddies</span> (SWODDIES) in the southern Bay of Biscay in 1990," Deep-Sea Res., Part A 39, 1147 (1992)]. In the remote-sensing infrared images, at the initial stage of observations, the anticyclone was accompanied by two cyclonic <span class="hlt">eddies</span>, so the entire structure appeared as a tripole. However, at later stages, only the anticyclone was seen in the images, traveling generally west. Unusual for an individual <span class="hlt">eddy</span> were the high speed of its motion (relative to the expected planetary beta-drift) and the presence of almost cycloidal meanders in its trajectory. Although surface satellites seem to have quickly disappeared, we hypothesize that subsurface satellites continued to exist, and the coherence of the three vortices persisted for a long time. A significant perturbation of the central symmetry in the mutual arrangement of three <span class="hlt">eddies</span> constituting a tripole can make reasonably fast cycloidal drift possible. This hypothesis is tested with two-layer contour-dynamics f-plane simulations and with finite-difference beta-plane simulations. In the latter case, the interplay of the planetary beta-effect and that due to the sloping bottom is considered.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005AGUSMOS52A..02F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005AGUSMOS52A..02F"><span>Modification of ocean-estuary salt fluxes by density-driven advection of a headland <span class="hlt">eddy</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fram, J. P.; Stacey, M. T.</p> <p>2005-05-01</p> <p>Scalar exchange between San Francisco Bay and the coastal ocean is examined using shipboard observations made across the Golden Gate Channel. Ocean-estuary exchange is often described as a combination of two independent types of mechanisms: density-driven exchange such as gravitational circulation and tidal asymmetries such as tidal trapping. In this study we found that exchange is also governed by an interaction between these mechanisms. Tidally trapped <span class="hlt">eddies</span> created in shallow shoals are mixed into the main channel earlier in the tidal cycle during the rainy season because the <span class="hlt">eddies</span> are pushed seaward by gravitational circulation. This interaction increases the tidally averaged dispersive salt flux into the bay. The study consists of experiments during each of three 'seasons': winter/spring runoff (March 2002), summer upwelling (July 2003), and fall relaxation (October 2002). Within each experiment, transects across the channel were repeated approximately every 12 minutes for 25 hours during both spring tide and the following neap tide. Velocity was measured from a boat-mounted ADCP. Scalar concentrations were measured from a tow-yoed SeaSciences Acrobat. Salinity exchange over each spring-neap cycle is quantified with harmonic analysis. Harmonic results are decomposed into flux mechanisms using temporal and spatial <span class="hlt">correlations</span>. The temporal <span class="hlt">correlation</span> of cross-sectional averaged salinity and velocity (tidal pumping flux) is the largest part of the dispersive flux of salinity into the bay. From the tidal pumping portion of the dispersive flux, it is shown that there is less exchange than was found in earlier studies. Furthermore, tidal pumping flux scales strongly with flow due to density-driven movement of tidally trapped <span class="hlt">eddies</span> and density-driven increases in ebb-flood frictional phasing. Complex bathymetry makes salinity exchange scale differently with flow than would be expected from simple tidal pumping and gravitational circulation models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.5046U','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.5046U"><span><span class="hlt">Eddy</span>-driven nutrient transport and associated upper-ocean primary production along the Kuroshio</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Uchiyama, Yusuke; Suzue, Yota; Yamazaki, Hidekatsu</p> <p>2017-06-01</p> <p>The Kuroshio is one of the most energetic western boundary currents accompanied by vigorous <span class="hlt">eddy</span> activity both on mesoscale and submesoscale, which affects biogeochemical processes in the upper ocean. We examine the primary production around the Kuroshio off Japan using a climatological ocean modeling based on the Regional Oceanic Modeling System (ROMS) coupled with a nitrogen-based nutrient, phytoplankton and zooplankton, and detritus (NPZD) biogeochemical model in a submesoscale <span class="hlt">eddy</span>-permitting configuration. The model indicates significant differences of the biogeochemical responses to <span class="hlt">eddy</span> activities in the Kuroshio Region (KR) and Kuroshio Extension Region (KE). In the KR, persisting cyclonic <span class="hlt">eddies</span> developed between the Kuroshio and coastline are responsible for upwelling-induced eutrophication. However, the <span class="hlt">eddy</span>-induced vertical nutrient flux counteracts and promotes pronounced southward and downward diapycnal nutrient transport from the mixed-layer down beneath the main body of the Kuroshio, which suppresses the near-surface productivity. In contrast, the KE has a 23.5% higher productivity than the KR, even at comparable <span class="hlt">eddy</span> intensity. Upward nutrient transport prevails near the surface due to predominant cyclonic <span class="hlt">eddies</span>, particularly to the north of the KE, where the downward transport barely occurs, except at depths deeper than 400 m and to a much smaller degree than in the KR. The <span class="hlt">eddy</span> energy conversion analysis reveals that the combination of shear instability around the mainstream of the Kuroshio with prominent baroclinic instability near the Kuroshio front is essential for the generation of <span class="hlt">eddies</span> in the KR, leading to the increase of the <span class="hlt">eddy</span>-induced vertical nitrate transport around the Kuroshio.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.H34D..03H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.H34D..03H"><span>The current California drought through <span class="hlt">EDDI</span>'s eyes: early warning and monitoring of agricultural and hydrologic drought with the new Evaporative Demand Drought Index.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hobbins, M.; McEvoy, D.; Huntington, J. L.; Wood, A. W.; Morton, C.; Verdin, J. P.</p> <p>2015-12-01</p> <p> hydrologic droughts, with <span class="hlt">correlations</span> to water-year streamflow that are highest at the 9- to 12-month aggregation periods, and during the summer. <span class="hlt">EDDI</span> shows significant promise as a leading indicator of drought, thereby providing a valuable planning window for growers and water resource managers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016GeoRL..4312234A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016GeoRL..4312234A"><span>Oceanic <span class="hlt">eddy</span> detection and lifetime forecast using machine learning methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ashkezari, Mohammad D.; Hill, Christopher N.; Follett, Christopher N.; Forget, Gaël.; Follows, Michael J.</p> <p>2016-12-01</p> <p>We report a novel altimetry-based machine learning approach for <span class="hlt">eddy</span> identification and characterization. The machine learning models use daily maps of geostrophic velocity anomalies and are trained according to the phase angle between the zonal and meridional components at each grid point. The trained models are then used to identify the corresponding <span class="hlt">eddy</span> phase patterns and to predict the lifetime of a detected <span class="hlt">eddy</span> structure. The performance of the proposed method is examined at two dynamically different regions to demonstrate its robust behavior and region independency.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.B11B0430T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.B11B0430T"><span>N2O fluxes over a corn field from an open-path, laser-based <span class="hlt">eddy</span> covariance system and static chambers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tao, L.; Pan, D.; Gelfand, I.; Abraha, M.; Moyer, R.; Poe, A.; Sun, K.; Robertson, P.; Zondlo, M. A.</p> <p>2015-12-01</p> <p>Nitrous oxide (N2O) is important greenhouse and ozone-depleting gase. Although many efforts have been paid to N2O emissions, the spatial and temporal variability of N2O emissions still subject to large uncertainty. Application of the <span class="hlt">eddy</span> covariance method for N2O emissions research would allow continuous ecosystem level flux measurements. The caveat, however, is need for high precision and high frequency measurements in field. In this study, an open-path, quantum cascade-laser-based <span class="hlt">eddy</span> covariance N2O sensor has been deployed nearly continuously since May 2015 over a corn field at the W.K. Kellogg Biological Station site in SW Michigan. The field precision of the N2O sensor was assessed to be 0.1 ppbv at 10 Hz, and the total consumption was ~ 40 W, allowing the system to be powered solely by solar panels. The stability of the sensor under different temperature and humidity was tested within an environmental chamber. Spectroscopic experiments and cospectra analyses were carried out to study specific corrections associated with the sensor for <span class="hlt">eddy</span> covariance <span class="hlt">techniques</span>, including the line broadening effect due to water vapor and high frequency flux attenuation owning to sample path averaging. Ogive analyses indicated that the high-frequency N2O flux loss due to various damping effects was comparable to those of the CO2 flux. The detection limit of flux was estimated to be 0.3 ng N s-1 m-2 with a flux averaging interval of 30 minutes. The results from the EC system were also compared with ground measurements by standard static chambers (SC). Overall, more than 150 individual chamber measurements were taken within the footprint of the EC system. We found good <span class="hlt">correlation</span> between the EC and SC methods given the spatiotemporal differences between the two <span class="hlt">techniques</span> (R2 = 0.75). Both methods detected increased emissions during afternoon as compared to morning and night hours. Differences between EC and SC were also studied by investigating spatial variability with a</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/6284606','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/biblio/6284606"><span><span class="hlt">Eddy</span> current inspection tool. [Patent application</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Petrini, R.R.; Van Lue, D.F.</p> <p>1980-10-29</p> <p>A miniaturized inspection tool, for testing and inspection of metal objects in locations with difficult accessibility, which comprises <span class="hlt">eddy</span> current sensing equipment with a probe coil, and associated coaxial coil cable, oil energizing means, and circuit means responsive to impedance changes in the coil as effected by induced <span class="hlt">eddy</span> currents in a test object to produce a data output signal proportional to such changes. The coil and cable are slideably received in the utility channel of the flexible insertion tube of a fiberoptic scope. The scope is provided with light transmitting and receiving fiberoptics for viewing through the flexible tube, and articulation means for articulating the distal end of the tube and permitting close control of coil placement relative to a test object. The <span class="hlt">eddy</span> current sensing equipment includes a tone generator for generating audible signals responsive to the data output signal. In one selected mode of operation, the tone generator responsive to the output signal above a selected level generates a constant single frequency tone for signalling detection of a discontinuity and, in a second selected mode, generates a tone whose frequency is proportional to the difference between the output signal and a predetermined selected threshold level.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO24B2956R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO24B2956R"><span>Anisotropic Shear Dispersion Parameterization for Mesoscale <span class="hlt">Eddy</span> Transport</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reckinger, S. J.; Fox-Kemper, B.</p> <p>2016-02-01</p> <p>The effects of mesoscale <span class="hlt">eddies</span> are universally treated isotropically in general circulation models. However, the processes that the parameterization approximates, such as shear dispersion, typically have strongly anisotropic characteristics. The Gent-McWilliams/Redi mesoscale <span class="hlt">eddy</span> parameterization is extended for anisotropy and tested using 1-degree Community Earth System Model (CESM) simulations. The sensitivity of the model to anisotropy includes a reduction of temperature and salinity biases, a deepening of the southern ocean mixed-layer depth, and improved ventilation of biogeochemical tracers, particularly in oxygen minimum zones. The parameterization is further extended to include the effects of unresolved shear dispersion, which sets the strength and direction of anisotropy. The shear dispersion parameterization is similar to drifter observations in spatial distribution of diffusivity and high-resolution model diagnosis in the distribution of <span class="hlt">eddy</span> flux orientation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002GeoRL..29.2025B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002GeoRL..29.2025B"><span>Gulf of Aden <span class="hlt">eddies</span> and their impact on Red Sea Water</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bower, Amy S.; Fratantoni, David M.; Johns, William E.; Peters, Hartmut</p> <p>2002-11-01</p> <p>New oceanographic observations in the Gulf of Aden in the northwestern Indian Ocean have revealed large, energetic, deep-reaching mesoscale <span class="hlt">eddies</span> that fundamentally influence the spreading rates and pathways of intermediate-depth Red Sea Water (RSW). Three <span class="hlt">eddies</span> were sampled in February 2001, two cyclonic and one anticyclonic, with diameters 150-250 km. Both cyclones had surface-intensified velocity structure with maxima ~0.5 m s-1, while the equally-energetic anticyclone appeared to be decoupled from the surface circulation. All three <span class="hlt">eddies</span> reached nearly to the 1000-2000 m deep sea floor, with speeds as high as 0.2-0.3 m s-1 extending through the depth range of RSW. Comparison of salinity and direct velocity measurements indicates that the <span class="hlt">eddies</span> advect and stir RSW through the Gulf of Aden. Anomalous water properties in the center of the anticyclonic <span class="hlt">eddy</span> point to a possible formation site in the Somali Current System.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880053846&hterms=diffusion+concept&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddiffusion%2Bconcept','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880053846&hterms=diffusion+concept&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddiffusion%2Bconcept"><span>Venus' superrotation, mixing length theory and <span class="hlt">eddy</span> diffusion - A parametric study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mayr, H. G.; Harris, I.; Schatten, K. H.; Stevens-Rayburn, D. R.; Chan, K. L.</p> <p>1988-01-01</p> <p>The concept of the Hadley mechanism is adopted to describe the axisymmetric circulation of the Venus atmosphere. It is shown that, for the atmosphere of a slowly rotating planet such as Venus, a form of the nonliner 'closure' (self-consistent solution) of the fluid dynamics system which constrains the magnitude of the <span class="hlt">eddy</span> diffusion coefficients can be postulated. A nonlinear one-layer spectral model of the zonally symmetric circulation was then used to establish the relationship between the heat source, the meridional circulation, and the <span class="hlt">eddy</span> diffusion coefficients, yielding large zonal velocities. Computer experiments indicated that proportional changes in the heat source and <span class="hlt">eddy</span> diffusion coefficients do not significantly change the zonal velocities. It was also found that, for large <span class="hlt">eddy</span> diffusion coefficients, the meridional velocity is virtually constant; below a threshold in the diffusion rate, the meridional velocity decreases; and, for large <span class="hlt">eddy</span> diffusion and small heating rates, the zonal velocities decrease with decreasing planetary rotation rates.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1057033','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1057033"><span>Calculation of <span class="hlt">Eddy</span> Currents In the CTH Vacuum Vessel and Coil Frame</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>A. Zolfaghari, A. Brooks, A. Michaels, J. Hanson, and G. Hartwell</p> <p>2012-09-25</p> <p>Knowledge of <span class="hlt">eddy</span> currents in the vacuum vessel walls and nearby conducting support structures can significantly contribute to the accuracy of Magnetohydrodynamics (MHD) equilibrium reconstruction in toroidal plasmas. Moreover, the magnetic fields produced by the <span class="hlt">eddy</span> currents could generate error fields that may give rise to islands at rational surfaces or cause field lines to become chaotic. In the Compact Toroidal Hybrid (CTH) device (R0 = 0.75 m, a = 0.29 m, B ≤ 0.7 T), the primary driver of the <span class="hlt">eddy</span> currents during the plasma discharge is the changing flux of the ohmic heating transformer. Electromagnetic simulations are usedmore » to calculate <span class="hlt">eddy</span> current paths and profile in the vacuum vessel and in the coil frame pieces with known time dependent currents in the ohmic heating coils. MAXWELL and SPARK codes were used for the Electromagnetic modeling and simulation. MAXWELL code was used for detailed 3D finite-element analysis of the <span class="hlt">eddy</span> currents in the structures. SPARK code was used to calculate the <span class="hlt">eddy</span> currents in the structures as modeled with shell/surface elements, with each element representing a current loop. In both cases current filaments representing the <span class="hlt">eddy</span> currents were prepared for input into VMEC code for MHD equilibrium reconstruction of the plasma discharge. __________________________________________________« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.9948H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.9948H"><span>Momentum, sensible heat and CO2 <span class="hlt">correlation</span> coefficient variability: what can we learn from 20 years of continuous <span class="hlt">eddy</span> covariance measurements?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hurdebise, Quentin; Heinesch, Bernard; De Ligne, Anne; Vincke, Caroline; Aubinet, Marc</p> <p>2017-04-01</p> <p>Long-term data series of carbon dioxide and other gas exchanges between terrestrial ecosystems and atmosphere become more and more numerous. Long-term analyses of such exchanges require a good understanding of measurement conditions during the investigated period. Independently of climate drivers, measurements may indeed be influenced by measurement conditions themselves subjected to long-term variability due to vegetation growth or set-up changes. The present research refers to the Vielsalm Terrestrial Observatory (VTO) an ICOS candidate site located in a mixed forest (beech, silver fir, Douglas fir, Norway spruce) in the Belgian Ardenne. Fluxes of momentum, carbon dioxide and sensible heat have been continuously measured there by <span class="hlt">eddy</span> covariance for more than 20 years. During this period, changes in canopy height and measurement height occurred. The <span class="hlt">correlation</span> coefficients (for momemtum, sensible heat and CO2) and the normalized standard deviations measured for the past 20 years at the Vielsalm Terrestrial Observatory (VTO) were analysed in order to define how the fluxes, independently of climate conditions, were affected by the surrounding environment evolution, including tree growth, forest thinning and tower height change. A relationship between canopy aerodynamic distance and the momentum <span class="hlt">correlation</span> coefficient was found which is characteristic of the roughness sublayer, and suggests that momentum transport processes were affected by z-d. In contrast, no relationship was found for sensible heat and CO2 <span class="hlt">correlation</span> coefficients, suggesting that the z-d variability observed did not affect their turbulent transport. There were strong differences in these coefficients, however, between two wind sectors, characterized by contrasted stands (height differences, homogeneity) and different hypotheses were raised to explain it. This study highlighted the importance of taking the surrounding environment variability into account in order to ensure the spatio</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.C21D1157M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.C21D1157M"><span>Observational Inferences of Lateral <span class="hlt">Eddy</span> Diffusivity in the Halocline of the Beaufort Gyre</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meneghello, G.; Marshall, J.; Cole, S. T.; Timmermans, M. L.</p> <p>2017-12-01</p> <p>Using Ekman pumping rates mediated by sea-ice in the Arctic Ocean's Beaufort Gyre (BG), the magnitude of lateral <span class="hlt">eddy</span> diffusivities required to balance downward pumping is inferred. In this limit — that of vanishing residual-mean circulation — <span class="hlt">eddy</span>-induced upwelling exactly balances downward pumping. The implied <span class="hlt">eddy</span> diffusivity varies spatially with values of 50-400 m2/s, and decays with depth. <span class="hlt">Eddy</span> diffusivity estimated using mixing length theory applied to BG mooring data exhibits a similar range of values from 100 m2/s to more than 600 m2/s, and also decays with depth. We conclude that <span class="hlt">eddy</span> diffusivities in the BG are likely large enough to balance downward Ekman pumping, arresting the deepening of the gyre and suggesting that <span class="hlt">eddies</span> play a zero-order role in buoyancy and freshwater budgets of the BG.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017GeoRL..4412331M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017GeoRL..4412331M"><span>Observational Inferences of Lateral <span class="hlt">Eddy</span> Diffusivity in the Halocline of the Beaufort Gyre</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Meneghello, Gianluca; Marshall, John; Cole, Sylvia T.; Timmermans, Mary-Louise</p> <p>2017-12-01</p> <p>Using Ekman pumping rates mediated by sea ice in the Arctic Ocean's Beaufort Gyre (BG), the magnitude of lateral <span class="hlt">eddy</span> diffusivities required to balance downward pumping is inferred. In this limit—that of vanishing residual-mean circulation—<span class="hlt">eddy</span>-induced upwelling exactly balances downward pumping. The implied <span class="hlt">eddy</span> diffusivity varies spatially and decays with depth, with values of 50-400 m2/s. <span class="hlt">Eddy</span> diffusivity estimated using mixing length theory applied to BG mooring data exhibits a similar decay with depth and range of values from 100 m2/s to more than 600 m2/s. We conclude that <span class="hlt">eddy</span> diffusivities in the BG are likely large enough to balance downward Ekman pumping, arresting the deepening of the gyre and suggesting that <span class="hlt">eddies</span> play a zero-order role in buoyancy and freshwater budgets of the BG.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A53I..07B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A53I..07B"><span><span class="hlt">Eddy</span>-Covariance Observations and Large-<span class="hlt">Eddy</span>-Simulations of Near-Shore Fluxes from Water Bodies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bohrer, G.; Rey Sanchez, C.; Kenny, W.; Morin, T. H.</p> <p>2017-12-01</p> <p><span class="hlt">Eddy</span> covariance (EC) measurement <span class="hlt">techniques</span> are increasingly used in the study of lakes and coastal ecosystems. The sharp water-shore transitions in energy forcing and surface roughness are challenging the validity of the EC approach at these sites. We discuss the results of two seasonal campaigns to measure CO2 and water-vapor fluxes in coastal environments - a small lake in Michigan, and the water over a coral reef in the Red, Sea, Israel. We show that in both environments, horizontal advection of CO2 and water vapor is responsible to a non-negligible component of the total flux to/from the water. We used a two-tower approach to measure fluxes from the water and from the shore and calculate the advection and flux divergence between the two. An empirical footprint model was used to filter the observations and keep only the times when interference from the shore-line transition is minimal. Observations of both vertical turbulent fluxes and advection were gapfilled with a neural-network model, based on their observed relationships with environmental forcing. Gap-filled observations were used to determine the seasonal net fluxes for the tow ecosystems. We used Large-<span class="hlt">Eddy</span> Simulations (LES) to conduct a case study of airflow patterns associated with a small inland lake surrounded by forest (i.e. radius of lake only ten times the height of the forest). We combined LES outputs with scalar dispersion simulations to model potential biases in EC flux measurements due to the heterogeneity of surface fluxes and vertical advection. Our simulations show that the lake-to-forest transition can induce a non-zero vertical wind component, which will strongly affect the interpretation of wind and flux measurements. Furthermore, significant horizontal gradients of CO2 are generated by the forest carbon sink and lake carbon source, which are further transported by local roughness-induced circulation. We simulated six hypothetical flux tower locations along a downwind gradient at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018AIPA....8e6602Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018AIPA....8e6602Y"><span>Influence of magnet <span class="hlt">eddy</span> current on magnetization characteristics of variable flux memory machine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Hui; Lin, Heyun; Zhu, Z. Q.; Lyu, Shukang</p> <p>2018-05-01</p> <p>In this paper, the magnet <span class="hlt">eddy</span> current characteristics of a newly developed variable flux memory machine (VFMM) is investigated. Firstly, the machine structure, non-linear hysteresis characteristics and <span class="hlt">eddy</span> current modeling of low coercive force magnet are described, respectively. Besides, the PM <span class="hlt">eddy</span> current behaviors when applying the demagnetizing current pulses are unveiled and investigated. The mismatch of the required demagnetization currents between the cases with or without considering the magnet <span class="hlt">eddy</span> current is identified. In addition, the influences of the magnet <span class="hlt">eddy</span> current on the demagnetization effect of VFMM are analyzed. Finally, a prototype is manufactured and tested to verify the theoretical analyses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26096666','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26096666"><span>PSF mapping-based correction of <span class="hlt">eddy</span>-current-induced distortions in diffusion-weighted echo-planar imaging.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>In, Myung-Ho; Posnansky, Oleg; Speck, Oliver</p> <p>2016-05-01</p> <p>To accurately correct diffusion-encoding direction-dependent <span class="hlt">eddy</span>-current-induced geometric distortions in diffusion-weighted echo-planar imaging (DW-EPI) and to minimize the calibration time at 7 Tesla (T). A point spread function (PSF) mapping based <span class="hlt">eddy</span>-current calibration method is newly presented to determine <span class="hlt">eddy</span>-current-induced geometric distortions even including nonlinear <span class="hlt">eddy</span>-current effects within the readout acquisition window. To evaluate the temporal stability of <span class="hlt">eddy</span>-current maps, calibration was performed four times within 3 months. Furthermore, spatial variations of measured <span class="hlt">eddy</span>-current maps versus their linear superposition were investigated to enable correction in DW-EPIs with arbitrary diffusion directions without direct calibration. For comparison, an image-based <span class="hlt">eddy</span>-current correction method was additionally applied. Finally, this method was combined with a PSF-based susceptibility-induced distortion correction approach proposed previously to correct both susceptibility and <span class="hlt">eddy</span>-current-induced distortions in DW-EPIs. Very fast <span class="hlt">eddy</span>-current calibration in a three-dimensional volume is possible with the proposed method. The measured <span class="hlt">eddy</span>-current maps are very stable over time and very similar maps can be obtained by linear superposition of principal-axes <span class="hlt">eddy</span>-current maps. High resolution in vivo brain results demonstrate that the proposed method allows more efficient <span class="hlt">eddy</span>-current correction than the image-based method. The combination of both PSF-based approaches allows distortion-free images, which permit reliable analysis in diffusion tensor imaging applications at 7T. © 2015 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JPhD...49o5303C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JPhD...49o5303C"><span><span class="hlt">Eddy</span> current characterization of small cracks using least square support vector machine</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chelabi, M.; Hacib, T.; Le Bihan, Y.; Ikhlef, N.; Boughedda, H.; Mekideche, M. R.</p> <p>2016-04-01</p> <p><span class="hlt">Eddy</span> current (EC) sensors are used for non-destructive testing since they are able to probe conductive materials. Despite being a conventional <span class="hlt">technique</span> for defect detection and localization, the main weakness of this <span class="hlt">technique</span> is that defect characterization, of the exact determination of the shape and dimension, is still a question to be answered. In this work, we demonstrate the capability of small crack sizing using signals acquired from an EC sensor. We report our effort to develop a systematic approach to estimate the size of rectangular and thin defects (length and depth) in a conductive plate. The achieved approach by the novel combination of a finite element method (FEM) with a statistical learning method is called least square support vector machines (LS-SVM). First, we use the FEM to design the forward problem. Next, an algorithm is used to find an adaptive database. Finally, the LS-SVM is used to solve the inverse problems, creating polynomial functions able to approximate the <span class="hlt">correlation</span> between the crack dimension and the signal picked up from the EC sensor. Several methods are used to find the parameters of the LS-SVM. In this study, the particle swarm optimization (PSO) and genetic algorithm (GA) are proposed for tuning the LS-SVM. The results of the design and the inversions were compared to both simulated and experimental data, with accuracy experimentally verified. These suggested results prove the applicability of the presented approach.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_16");'>16</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li class="active"><span>18</span></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_18 --> <div id="page_19" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="361"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1994PhDT.......217B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1994PhDT.......217B"><span>Novel <span class="hlt">Techniques</span> for Pulsed Field Gradient NMR Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Brey, William Wallace</p> <p></p> <p>Pulsed field gradient (PFG) <span class="hlt">techniques</span> now find application in multiple quantum filtering and diffusion experiments as well as in magnetic resonance imaging and spatially selective spectroscopy. Conventionally, the gradient fields are produced by azimuthal and longitudinal currents on the surfaces of one or two cylinders. Using a series of planar units consisting of azimuthal and radial current elements spaced along the longitudinal axis, we have designed gradient coils having linear regions that extend axially nearly to the ends of the coil and to more than 80% of the inner radius. These designs locate the current return paths on a concentric cylinder, so the coils are called Concentric Return Path (CRP) coils. Coils having extended linear regions can be made smaller for a given sample size. Among the advantages that can accrue from using smaller coils are improved gradient strength and switching time, reduced <span class="hlt">eddy</span> currents in the absence of shielding, and improved use of bore space. We used an approximation <span class="hlt">technique</span> to predict the remaining <span class="hlt">eddy</span> currents and a time-domain model of coil performance to simulate the electrical performance of the CRP coil and several reduced volume coils of more conventional design. One of the conventional coils was designed based on the time-domain performance model. A single-point acquisition <span class="hlt">technique</span> was developed to measure the remaining <span class="hlt">eddy</span> currents of the reduced volume coils. Adaptive sampling increases the dynamic range of the measurement. Measuring only the center of the stimulated echo removes chemical shift and B_0 inhomogeneity effects. The <span class="hlt">technique</span> was also used to design an inverse filter to remove the <span class="hlt">eddy</span> current effects in a larger coil set. We added pulsed field gradient and imaging capability to a 7 T commercial spectrometer to perform neuroscience and embryology research and used it in preliminary studies of binary liquid mixtures separating near a critical point. These <span class="hlt">techniques</span> and coil designs will find</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996JGR...10120629B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996JGR...10120629B"><span>Cleavage of a Gulf of Mexico Loop Current <span class="hlt">eddy</span> by a deep water cyclone</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Biggs, D. C.; Fargion, G. S.; Hamilton, P.; Leben, R. R.</p> <p>1996-09-01</p> <p><span class="hlt">Eddy</span> Triton, an anticyclonic <span class="hlt">eddy</span> shed by the Loop Current in late June 1991, drifted SW across the central Gulf of Mexico in the first 6 months of 1992, along the ``southern'' of the three characteristic drift paths described by Vukovich and Crissman [1986] from their analyses of 13 years of advanced very high resolution radiometer sea surface temperature data. An expendable bathythermograph (XBT) and conductivity-temperature-depth (CTD) transect of opportunity through Triton at <span class="hlt">eddy</span> age 7 months in January 1992 found that <span class="hlt">eddy</span> interior stood 23 dyn. cm higher than periphery; this gradient drove an anticyclonic swirl transport of 9-10 Sv relative to 800 dbar. At <span class="hlt">eddy</span> age 9-10 months and while this <span class="hlt">eddy</span> was in deep water near 94°W, it interacted with a mesoscale cyclonic circulation and was cleaved into two parts. The major (greater dynamic centimeters) piece drifted NW to end up in the ``<span class="hlt">eddy</span> graveyard'' in the NW corner of the gulf, while the minor piece drifted SW and reached the continental margin of the western gulf off Tuxpan. This southern piece of <span class="hlt">Eddy</span> Triton then turned north to follow the 2000-m isobath to about 24°N and later coalesced with what remained of the major fragment. Because <span class="hlt">Eddy</span> Triton's cleavage took place just before the start of marine mammals (GulfCet) and Louisiana-Texas physical oceanography (LATEX) field programs, the closely spaced CTD, XBT, and air dropped XBT (AXBT) data that were gathered on the continental margin north of 26°N in support of these programs allow a detailed look at the northern margin of the larger fragment of this <span class="hlt">eddy</span>. Supporting data from the space-borne altimeters on ERS 1 and TOPEX/POSEIDON allow us to track both pieces of <span class="hlt">Eddy</span> Triton in the western Gulf and follow their spin down in dynamic height, coalescence, and ultimate entrainment in January 1993 into another anticyclonic <span class="hlt">eddy</span> (<span class="hlt">Eddy</span> U).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29187679','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29187679"><span>Cardiac-driven Pulsatile Motion of Intracranial Cerebrospinal Fluid Visualized Based on a <span class="hlt">Correlation</span> Mapping <span class="hlt">Technique</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yatsushiro, Satoshi; Sunohara, Saeko; Hayashi, Naokazu; Hirayama, Akihiro; Matsumae, Mitsunori; Atsumi, Hideki; Kuroda, Kagayaki</p> <p>2018-04-10</p> <p>A <span class="hlt">correlation</span> mapping <span class="hlt">technique</span> delineating delay time and maximum <span class="hlt">correlation</span> for characterizing pulsatile cerebrospinal fluid (CSF) propagation was proposed. After proofing its technical concept, this <span class="hlt">technique</span> was applied to healthy volunteers and idiopathic normal pressure hydrocephalus (iNPH) patients. A time-resolved three dimensional-phase contrast (3D-PC) sampled the cardiac-driven CSF velocity at 32 temporal points per cardiac period at each spatial location using retrospective cardiac gating. The proposed <span class="hlt">technique</span> visualized distributions of propagation delay and <span class="hlt">correlation</span> coefficient of the PC-based CSF velocity waveform with reference to a waveform at a particular point in the CSF space. The delay time was obtained as the amount of time-shift, giving the maximum <span class="hlt">correlation</span> for the velocity waveform at an arbitrary location with that at the reference location. The validity and accuracy of the <span class="hlt">technique</span> were confirmed in a flow phantom equipped with a cardiovascular pump. The <span class="hlt">technique</span> was then applied to evaluate the intracranial CSF motions in young, healthy (N = 13), and elderly, healthy (N = 13) volunteers and iNPH patients (N = 13). The phantom study demonstrated that root mean square error of the delay time was 2.27%, which was less than the temporal resolution of PC measurement used in this study (3.13% of a cardiac cycle). The human studies showed a significant difference (P < 0.01) in the mean <span class="hlt">correlation</span> coefficient between the young, healthy group and the other two groups. A significant difference (P < 0.05) was also recognized in standard deviation of the <span class="hlt">correlation</span> coefficients in intracranial CSF space among all groups. The result suggests that the CSF space compliance of iNPH patients was lower than that of healthy volunteers. The <span class="hlt">correlation</span> mapping <span class="hlt">technique</span> allowed us to visualize pulsatile CSF velocity wave propagations as still images. The <span class="hlt">technique</span> may help to classify diseases related to CSF dynamics, such as iNPH.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFMOS31A1362B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFMOS31A1362B"><span>Impact of Preferred <span class="hlt">Eddy</span> Tracks on Transport and Mixing in the Eastern South Pacific</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Belmadani, A.; Donoso, D.; Auger, P. A.; Chaigneau, A.</p> <p>2017-12-01</p> <p>Mesoscale <span class="hlt">eddies</span>, which play a fundamental role in the transport of mass, heat, nutrients, and biota across the oceans, have been suggested to propagate preferently along specific tracks. These preferred pathways, also called <span class="hlt">eddy</span> trains, are near-zonal due to westward drift of individual vortices, and tend to be polarized (ie alternatively dominated by anticyclonic/cyclonic <span class="hlt">eddies</span>), coinciding with the recently discovered latent striations (quasi-zonal mesoscale jet-like features). While significant effort has been made to understand the dynamics of striations and their interplay with mesoscale <span class="hlt">eddies</span>, the impact of repeated <span class="hlt">eddy</span> tracks on physical (temperature, salinity), biogeochemical (oxygen, carbon, nutrients) and other tracers (e.g. chlorophyll, marine debris) has received little attention. Here we report on the results of numerical modeling experiments that simulate the impact of preferred <span class="hlt">eddy</span> tracks on the transport and mixing of water particles in the Eastern South Pacific off Chile. A 30-year interannual simulation of the oceanic circulation in this region has been performed over 1984-2013 with the ROMS (Regional Oceanic Modeling System) at an <span class="hlt">eddy</span>-resolving resolution (10 km). Objective tracking of mesoscale coherent vortices is obtained using automated methods, allowing to compute the contribution of <span class="hlt">eddies</span> to the ocean circulation. Preferred <span class="hlt">eddy</span> tracks are further isolated from the more random <span class="hlt">eddies</span>, by comparing the distances between individual tracks and the striated pattern in long-term mean <span class="hlt">eddy</span> polarity with a least-squares approach. The remaining non-<span class="hlt">eddying</span> flow may also be decomposed into time-mean and anomalous circulation, and/or small- and large-scale circulation. Neutrally-buoyant Lagrangian floats are then released uniformly into the various flow components as well as the total flow, and tracked forward in time with the ARIANE software. The dispersion patterns of water particles are used to estimate the respective contributions of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5927S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5927S"><span>Characterization and impact of "dead-zone" <span class="hlt">eddies</span> in the tropical Northeast Atlantic Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schuette, Florian; Karstensen, Johannes; Krahmann, Gerd; Hauss, Helena; Fiedler, Björn; Brandt, Peter; Visbeck, Martin; Körtzinger, Arne</p> <p>2016-04-01</p> <p>Localized open-ocean low-oxygen dead-zones in the tropical Northeast Atlantic are recently discovered ocean features that can develop in dynamically isolated water masses within cyclonic <span class="hlt">eddies</span> (CE) and anticyclonic modewater <span class="hlt">eddies</span> (ACME). Analysis of a comprehensive oxygen dataset obtained from gliders, moorings, research vessels and Argo floats shows that <span class="hlt">eddies</span> with low oxygen concentrations at 50-150 m depths can be found in surprisingly high numbers and in a large area (from about 5°N to 20°N, from the shelf at the eastern boundary to 30°W). Minimum oxygen concentrations of about 9 μmol/kg in CEs and close to anoxic concentrations (< 1 μmol/kg) in ACMEs were observed. In total, 495 profiles with oxygen concentrations below the minimum background concentration of 40 μmol/kg could be associated with 27 independent "dead-zone" <span class="hlt">eddies</span> (10 CEs; 17 ACMEs). The low oxygen concentration right beneath the mixed layer has been attributed to the combination of high productivity in the surface waters of the <span class="hlt">eddies</span> and the isolation of the <span class="hlt">eddies</span>' cores. Indeed <span class="hlt">eddies</span> of both types feature a cold sea surface temperature anomaly and enhanced chlorophyll concentrations in their center. The oxygen minimum is located in the <span class="hlt">eddy</span> core beneath the mixed layer at around 80 m depth. The mean oxygen anomaly between 50 to 150 m depth for CEs (ACMEs) is -49 (-81) μmol/kg. <span class="hlt">Eddies</span> south of 12°N carry weak hydrographic anomalies in their cores and seem to be generated in the open ocean away from the boundary. North of 12°N, <span class="hlt">eddies</span> of both types carry anomalously low salinity water of South Atlantic Central Water origin from the eastern boundary upwelling region into the open ocean. This points to an <span class="hlt">eddy</span> generation near the eastern boundary. A conservative estimate yields that around 5 dead-zone <span class="hlt">eddies</span> (4 CEs; 1 ACME) per year entering the area north of 12°N between the Cap Verde Islands and 19°W. The associated contribution to the oxygen budget of the shallow oxygen minimum</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JPhCS.546a2021M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JPhCS.546a2021M"><span><span class="hlt">Correlation</span> between near infrared spectroscopy and electrical <span class="hlt">techniques</span> in measuring skin moisture content</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Mohamad, M.; Sabbri, A. R. M.; Mat Jafri, M. Z.; Omar, A. F.</p> <p>2014-11-01</p> <p>Near infrared (NIR) spectroscopy <span class="hlt">technique</span> serves as an important tool for the measurement of moisture content of skin owing to the advantages it has over the other <span class="hlt">techniques</span>. The purpose of the study is to develop a <span class="hlt">correlation</span> between NIR spectrometer with electrical conventional <span class="hlt">techniques</span> for skin moisture measurement. A non-invasive measurement of moisture content of skin was performed on different part of human face and hand under control environment (temperature 21 ± 1 °C, relative humidity 45 ± 5 %). Ten healthy volunteers age between 21-25 (male and female) participated in this study. The moisture content of skin was measured using DermaLab® USB Moisture Module, Scalar Moisture Checker and NIR spectroscopy (NIRQuest). Higher <span class="hlt">correlation</span> was observed between NIRQuest and Dermalab moisture probe with a coefficient of determination (R2) above 70 % for all the subjects. However, the value of R2 between NIRQuest and Moisture Checker was observed to be lower with the R2 values ranges from 51.6 to 94.4 %. The <span class="hlt">correlation</span> of NIR spectroscopy <span class="hlt">technique</span> successfully developed for measuring moisture content of the skin. The analysis of this <span class="hlt">correlation</span> can help to establish novel instruments based on an optical system in clinical used especially in the dermatology field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19920000764&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DEddy%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19920000764&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DEddy%2Bcurrent"><span>Enhanced <span class="hlt">Eddy</span>-Current Detection Of Weld Flaws</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Van Wyk, Lisa M.; Willenberg, James D.</p> <p>1992-01-01</p> <p>Mixing of impedances measured at different frequencies reduces noise and helps reveal flaws. In new method, one excites <span class="hlt">eddy</span>-current probe simultaneously at two different frequencies; usually, one of which integral multiple of other. Resistive and reactive components of impedance of <span class="hlt">eddy</span>-current probe measured at two frequencies, mixed in computer, and displayed in real time on video terminal of computer. Mixing of measurements obtained at two different frequencies often "cleans up" displayed signal in situations in which band-pass filtering alone cannot: mixing removes most noise, and displayed signal resolves flaws well.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26715361','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26715361"><span><span class="hlt">Eddy</span> current compensated double diffusion encoded (DDE) MRI.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Mueller, Lars; Wetscherek, Andreas; Kuder, Tristan Anselm; Laun, Frederik Bernd</p> <p>2017-01-01</p> <p><span class="hlt">Eddy</span> currents might lead to image distortions in diffusion-weighted echo planar imaging. A method is proposed to reduce their effects on double diffusion encoding (DDE) MRI experiments and the thereby derived microscopic fractional anisotropy (μFA). The twice-refocused spin echo scheme was adapted for DDE measurements. To assess the effect of individual diffusion encodings on the image distortions, measurements of a grid of plastic rods in water were performed. The effect of <span class="hlt">eddy</span> current compensation on μFA measurements was evaluated in the brains of six healthy volunteers. The use of an <span class="hlt">eddy</span> current compensation reduced the signal variation. As expected, the distortions caused by the second encoding were larger than those of the first encoding, entailing a stronger need to compensate for them. For an optimal result, however, both encodings had to be compensated. The artifact reduction strongly improved the measurement of the μFA in ventricles and gray matter by reducing the overestimation. An effect of the compensation on absolute μFA values in white matter was not observed. It is advisable to compensate both encodings in DDE measurements for <span class="hlt">eddy</span> currents. Magn Reson Med 77:328-335, 2017. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2000JGR...10520461D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2000JGR...10520461D"><span>Aircraft assessment of trace compound fluxes in the atmosphere with Relaxed <span class="hlt">Eddy</span> Accumulation: Sensitivity to the conditions of selection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Delon, C.; Druilhet, A.; Delmas, R.; Greenberg, J.</p> <p>2000-08-01</p> <p>The Relaxed <span class="hlt">Eddy</span> Accumulation (REA) <span class="hlt">technique</span>, implemented aboard aircraft, may be used to measure a wide variety of trace gas fluxes at a regional scale. Its principle is rather simple: air is sampled at a constant rate and the flux is calculated by multiplying a constant β (0.58 in field experiment and 0.62 in simulations) by the standard deviation of the vertical velocity and by the difference between the average concentrations of the scalar (trace gas) for updrafts and downdrafts. The storage of the chemical compound in reservoirs allows for trace gas analysis in laboratory, when in situ measurement with fast response and high sensitivity sensors are not available. The REA method was implemented on the Avion de Recherche Atmosphérique et de Télédétection aircraft during the Experiment for Regional Sources and Sinks of Oxidants (EXPRESSO) campaign. The main requirement for accurate flux determination is the measurement of the vertical component of wind velocity in real time. A simulation <span class="hlt">technique</span> was developed to evaluate the performance of an aircraft REA. The influence of the time lag between the vertical velocity (W) measurement and REA control was tested, as well as the offset of W, the threshold, and the filtering imposed on W. Correction factors, used in a deployment of aircraft REA, were deduced from this study. An additional simulation was performed to evaluate the influence of spatial or temporal drifts on the scalar. The simulation showed that the REA method is not more disturbed than the <span class="hlt">Eddy</span> <span class="hlt">Correlation</span> method by low frequencies of physical origin, such as topography. The REA method was used during EXPRESSO for the measurement of isoprene fluxes over the wet savanna and the evergreen rain forest.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121.8208Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121.8208Z"><span>Nonlinear multiscale interactions and internal dynamics underlying a typical <span class="hlt">eddy</span>-shedding event at Luzon Strait</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Yuan-Bing; Liang, X. San; Gan, Jianping</p> <p>2016-11-01</p> <p><span class="hlt">Eddy</span>-shedding is a highly nonlinear process that presents a major challenge in geophysical fluid dynamics. Using the newly developed localized multiscale energy and vorticity analysis (MS-EVA), this study investigates an observed typical warm <span class="hlt">eddy</span>-shedding event as the Kuroshio passes the Luzon Strait, in order to gain insight into the underlying internal dynamics. Through multiscale window transform (MWT), it is found that the loop-form Kuroshio intrusion into the South China Sea (SCS) is not a transient feature, but a quasi-equilibrium state of the system. A mesoscale reconstruction reveals that the <span class="hlt">eddy</span> does not have its origin at the intrusion path, but comes from the Northwest Pacific. It propagates westward, preceded by a cyclonic (cold) <span class="hlt">eddy</span>, through the Kuroshio into the SCS. As the <span class="hlt">eddy</span> pair runs across the main current, the cold one weakens and the warm one intensifies through a mixed instability. In its development, another cold <span class="hlt">eddy</span> is generated to its southeast, which also experiences a mixed instability. It develops rapidly and cuts the warm <span class="hlt">eddy</span> off the stream. Both the warm and cold <span class="hlt">eddies</span> then propagate westward in the form of a Rossby wave (first baroclinic mode). As the <span class="hlt">eddies</span> approach the Dongsha Islands, they experience another baroclinic instability, accompanied by a sudden accumulation of <span class="hlt">eddy</span> available potential energy. This part of potential energy is converted to <span class="hlt">eddy</span> kinetic energy through buoyancy conversion, and is afterward transferred back to the large-scale field through inverse cascading, greatly reducing the intensity of the <span class="hlt">eddy</span> and eventually leading to its demise.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020038410&hterms=nitrogen+production&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dnitrogen%2Bproduction','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020038410&hterms=nitrogen+production&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dnitrogen%2Bproduction"><span>Influence of Mesoscale <span class="hlt">Eddies</span> on New Production in the Sargasso Sea</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McGillicuddy , Dennis J., Jr.; Robinson, A. R.; Siegel, D. A.; Jannasch, H. W.; Johnson, R.; Dickey, T. D.; McNeil, J.; Michaels, A. F.; Knap, A. H.</p> <p>1998-01-01</p> <p>It is problematic that geochemical estimates of new production - that fraction of total primary production in surface waters fueled by externally supplied nutrients - in oligotrophic waters of the open ocean surpass that which can be sustained by the traditionally accepted mechanisms of nutrient supply. In the case of the Sargasso Sea, for example, these mechanisms account for less than half of the annual nutrient requirement indicated by new production estimates based on three independent transient-tracer <span class="hlt">techniques</span>. Specifically, approximately one-quarter to one-third of the annual nutrient requirement can be supplied by entrainment into the mixed layer during wintertime convection, with minor contributions from mixing in the thermocline and wind-driven transport (the potentially important role of nitrogen fixation - for which estimates vary by an order of magnitude in this region - is excluded from this budget). Here we present four lines of evidence - <span class="hlt">eddy</span>-resolving model simulations, high-resolution observations from moored instrumentation, shipboard surveys, and satellite data - which suggest that the vertical flux of nutrients induced by the dynamics of mesoscale <span class="hlt">eddies</span> is sufficient to balance the nutrient budget in the Sargasso Sea. Additional information is contained in the original extended abstract.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=20020071034&hterms=nitrogen+production&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dnitrogen%2Bproduction','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=20020071034&hterms=nitrogen+production&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dnitrogen%2Bproduction"><span>Influence of Mesoscale <span class="hlt">Eddies</span> on New Production in the Sargasso Sea</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>McGillicuddy, D. J., Jr.; Robinson, A. R.; Siegel, D. A.; Jannasch, H. W.; Johnson, R.; Dickey, T. D.; McNeil, J.; Michaels, A. F.; Knap, A. H.</p> <p>1998-01-01</p> <p>It is problematic that geochemical estimates of new production, that fraction of total primary production in surface waters fueled by externally supplied nutrients, in oligotrophic waters of the open ocean surpass that which can be sustained by the traditionally accepted mechanisms of nutrient supply. In the cam of the Sargasso Sea, for example, these mechanisms account for less than half of the annual nutrient requirement indicated by new production estimates based on three independent transient-tracer <span class="hlt">techniques</span>. Specifically, approximately one-quarter to one-third of the annual nutrient requirement can be supplied by entrainment into the mixed layer during wintertime convection, with minor contributions from mixing in the thermocline and wind-driven transport (the potentially important role of nitrogen fixation- for which estimates vary by an order of magnitude in this region- is excluded from this budget). Here we present four lines of evidence-<span class="hlt">eddy</span>-resolving model simulations, high-resolution observations from moored instrumentation, shipboard surveys and satellite data-which suggest that the vertical flux of nutrients induced by the dynamics of mesoscale <span class="hlt">eddies</span> is sufficient to balance the nutrient budget in the Sargasso Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011EOSTr..92...56J','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011EOSTr..92...56J"><span>Students, Scientists, and Family Commemorate the Life and Diverse Works of Jack <span class="hlt">Eddy</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Judge, Philip</p> <p>2011-02-01</p> <p><span class="hlt">Eddy</span> Cross-Disciplinary Symposium on Sun-Climate Research; Aspen, Colorado, 22-24 October 2010; In 1976, John Allen <span class="hlt">Eddy</span> published a seminal article (see Science, 192(4245), 1189-1202) revealing a link between the Little Ice Age, which occurred during the sixteenth through nineteenth centuries, and a period of low sunspot activity, which <span class="hlt">Eddy</span> called the “Maunder Minimum.” This work placed Sun-climate research on a firm scientific footing. <span class="hlt">Eddy</span> passed away on 10 June 2009. Following <span class="hlt">Eddy</span>'s passions for education and cross-disciplinary research, a symposium was held to expose talented college students to the science and politics of Sun-climate research. Funding from NASA's Living With a Star Targeted Research and Technology program and from the High Altitude Observatory, Advanced Study Program, and Integrated Science Program of the National Center for Atmospheric Research (NCAR) supported keynote speakers and provided scholarships for 30 students (junior year to Ph.D.) from diverse disciplines. <span class="hlt">Eddy</span>'s wife, Barbara, led a session devoted to personal recollections. Spencer Weart (American Institute of Physics) gave an after-dinner tribute using recordings of <span class="hlt">Eddy</span> from a 1999 interview.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45..834S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45..834S"><span>Circum-Antarctic Shoreward Heat Transport Derived From an <span class="hlt">Eddy</span>- and Tide-Resolving Simulation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Stewart, Andrew L.; Klocker, Andreas; Menemenlis, Dimitris</p> <p>2018-01-01</p> <p>Almost all heat reaching the bases of Antarctica's ice shelves originates from warm Circumpolar Deep Water in the open Southern Ocean. This study quantifies the roles of mean and transient flows in transporting heat across almost the entire Antarctic continental slope and shelf using an ocean/sea ice model run at <span class="hlt">eddy</span>- and tide-resolving (1/48°) horizontal resolution. Heat transfer by transient flows is approximately attributed to <span class="hlt">eddies</span> and tides via a decomposition into time scales shorter than and longer than 1 day, respectively. It is shown that <span class="hlt">eddies</span> transfer heat across the continental slope (ocean depths greater than 1,500 m), but tides produce a stronger shoreward heat flux across the shelf break (ocean depths between 500 m and 1,000 m). However, the tidal heat fluxes are approximately compensated by mean flows, leaving the <span class="hlt">eddy</span> heat flux to balance the net shoreward heat transport. The <span class="hlt">eddy</span>-driven cross-slope overturning circulation is too weak to account for the <span class="hlt">eddy</span> heat flux. This suggests that isopycnal <span class="hlt">eddy</span> stirring is the principal mechanism of shoreward heat transport around Antarctica, though likely modulated by tides and surface forcing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26891305','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26891305"><span>Detection and Inspection of Steel Bars in Reinforced Concrete Structures Using Active Infrared Thermography with Microwave Excitation and <span class="hlt">Eddy</span> Current Sensors.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Szymanik, Barbara; Frankowski, Paweł Karol; Chady, Tomasz; John Chelliah, Cyril Robinson Azariah</p> <p>2016-02-16</p> <p>The purpose of this paper is to present a multi-sensor approach to the detection and inspection of steel bars in reinforced concrete structures. In connection with our past experience related to non-destructive testing of different materials, we propose using two potentially effective methods: active infrared thermography with microwave excitation and the <span class="hlt">eddy</span> current <span class="hlt">technique</span>. In this article active infrared thermography with microwave excitation is analyzed both by numerical modeling and experiments. This method, based on thermal imaging, due to its characteriatics should be considered as a preliminary method for the assessment of relatively shallowly located steel bar reinforcements. The <span class="hlt">eddy</span> current <span class="hlt">technique</span>, on the other hand, allows for more detailed evaluation and detection of deeply located rebars. In this paper a series of measurement results, together with the initial identification of certain features of steel reinforcement bars will be presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-GSFC_20171208_Archive_e000750.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-GSFC_20171208_Archive_e000750.html"><span><span class="hlt">Eddies</span> in the Southern Ocean</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>2015-04-08</p> <p>The cloud cover over the Southern Ocean occasionally parts as it did on January 1, 2015 just west of the Drake Passage where the VIIRS instrument on the Suomi NPP satellite glimpsed the above collection of ocean-color delineated <span class="hlt">eddies</span> which have diameters ranging from a couple of kilometers to a couple of hundred kilometers. Recent studies indicate that <span class="hlt">eddy</span> activity has been increasing in the Southern Ocean with possible implications for climate change. Credit: NASA's OceanColor/Suomi NPP/VIIRS NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17534904','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17534904"><span>Longitudinal gradient coil optimization in the presence of transient <span class="hlt">eddy</span> currents.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Trakic, A; Liu, F; Lopez, H Sanchez; Wang, H; Crozier, S</p> <p>2007-06-01</p> <p>The switching of magnetic field gradient coils in magnetic resonance imaging (MRI) inevitably induces transient <span class="hlt">eddy</span> currents in conducting system components, such as the cryostat vessel. These secondary currents degrade the spatial and temporal performance of the gradient coils, and compensation methods are commonly employed to correct for these distortions. This theoretical study shows that by incorporating the <span class="hlt">eddy</span> currents into the coil optimization process, it is possible to modify a gradient coil design so that the fields created by the coil and the <span class="hlt">eddy</span> currents combine together to generate a spatially homogeneous gradient that follows the input pulse. Shielded and unshielded longitudinal gradient coils are used to exemplify this novel approach. To assist in the evaluation of transient <span class="hlt">eddy</span> currents induced within a realistic cryostat vessel, a low-frequency finite-difference time-domain (FDTD) method using the total-field scattered-field (TFSF) scheme was performed. The simulations demonstrate the effectiveness of the proposed method for optimizing longitudinal gradient fields while taking into account the spatial and temporal behavior of the <span class="hlt">eddy</span> currents.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSME24F0766G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSME24F0766G"><span>The Use of Mesoscale <span class="hlt">Eddies</span> and Gulf Stream Meanders by White Sharks Carcharodon carcharias</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gaube, P.; Thorrold, S.; Braun, C.; McGillicuddy, D. J., Jr.; Lawson, G. L.; Skomal, G. B.</p> <p>2016-02-01</p> <p>Large pelagic fishes like sharks, tuna, swordfish, and billfish spend a portion of their lives in the open ocean, yet their spatial distribution in this vast habitat remains relatively unknown. Mesoscale ocean <span class="hlt">eddies</span>, rotating vortices with radius scales of approximately 100 km, structure open ocean ecosystems from primary producers to apex predators by influencing nutrient distributions and transporting large trapped parcels of water over long distances. Recent advances in both the tagging and tracking of marine animals combined with improved detection and tracking of mesoscale <span class="hlt">eddies</span> has shed some light on the oceanographic features influencing their migrations. Here we show that white sharks use the interiors of anticyclonic and cyclonic <span class="hlt">eddies</span> differently, a previously undocumented behavior. While swimming in warm, subtropical water, white sharks preferentially inhabit anticyclonic <span class="hlt">eddies</span> compared to cyclonic <span class="hlt">eddies</span>. In the vicinity of the Gulf Stream, the depth and duration of dives recorded by an archival temperature- and depth-recording tag affixed to a large female are shown to be significantly deeper and longer in anticyclonic <span class="hlt">eddies</span> compared to those in cyclonic <span class="hlt">eddies</span>. This asymmetry is linked to positive subsurface temperature anomalies generated by anticyclonic <span class="hlt">eddies</span> that are more than 7 degrees C warmer than cyclonic <span class="hlt">eddies</span>, thus reducing the need for these animals to expend as much energy regulating their internal temperature. In addition, anticyclonic <span class="hlt">eddies</span> may be regions of enhance foraging success, as suggested by a series of acoustics surveys in the North Atlantic which indicated elevated mesopelagic fish biomass in anticyclones compared to cyclones.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOS.A34B2650L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOS.A34B2650L"><span>Baroclinic Instability and Energy Transfer underlying the Kuroshio <span class="hlt">eddy</span> shedding process in Luzon Strait</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lu, J.</p> <p>2016-02-01</p> <p>The Kuroshio <span class="hlt">eddy</span> shedding in Luzon Strait has been intensively studied, due to its important role in the energy budgets of the special gap-passing western boundary current and its potential influence to South China Sea. In this study, the <span class="hlt">eddy</span>-mean flow interaction is first diagnosed with two classical "stationary" methods. Both show that, in a "time-averaged" sense, baroclinic instability and energy transfer provides the energy source for Kuroshio anticyclonic <span class="hlt">eddy</span> shedding and the accompanied cyclonic <span class="hlt">eddy</span> growth in Luzon Strait (this <span class="hlt">eddy</span> pair will be called AC/C-Es for short). To take into account the "nonstationary and intermittent" nature, the temporal evolutions of energy transfer during a typical Kuroshio <span class="hlt">eddy</span> shedding process are investigated using the localized multi-scale-window energy and vorticity analysis, or MS-EVA for short. Two stages are roughly distinguished according to the evolutionary nature of this process: the growing stage and the shedding stage. In the growing stage, the energy source straddles both the AC/C-Es, indicating mean flow supplies potential energy to both AC/C-Es for growth; the energy transfer hot spot persistently strengthens and expands horizontally as well as vertically from 200-300m to 100-400m depth range, culminating in a maximum of approximately 1.5×10-7 m2s-3. In the shedding stage, the energy source moves onto the accompanied cyclonic <span class="hlt">eddy</span>, i.e., the mean flow now supplies energy mainly to the cyclonic <span class="hlt">eddy</span>, making it strong enough to cut off the anticyclonic <span class="hlt">eddy</span> from Kuroshio, leading to the Kuroshio <span class="hlt">eddy</span> shedding.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018MS%26E..318a2055K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018MS%26E..318a2055K"><span>Formation of Maximum <span class="hlt">Eddy</span> Current Force by Non Ferrous Materials</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kader, M. M. A.; Razali, Z. B.; Yasin, N. S. M.; Daud, M. H.</p> <p>2018-03-01</p> <p>This project is concerned with the study of <span class="hlt">eddy</span> current effects on various materials such as aluminum, copper and magnesium. Two types of magnets used in this study; magnetic ferrite (ZnFe+2O4) and magnetic neodymium (NdFeBN42). <span class="hlt">Eddy</span> current force will be exerted to these materials due to current flows along the magnet. This force depends on the type of magnet, type of material and the gap between the magnet and the material or between the two magnets. The results show that at constant magnet to material gap, the <span class="hlt">eddy</span> current force decreases as the magnet to magnet gap increases. Similarly, at constant magnet to magnet gap, the <span class="hlt">eddy</span> current force decreases as the magnet to material gap increases. The minimum force was achieved when the gap of magnet to material is maximum, similarly to the gap of magnet to magnet. The weakest force was between Copper and Neodymium at a magnet to material gap of 20 mm and magnet to magnet gap of 40 mm; the <span class="hlt">eddy</span> current force was 0.00048 N. The strongest force (maximum) was between Magnesium and Ferrite and 0.42273 N at a magnet to material gap of 3 mm and magnet to magnet gap of 5 mm.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_17");'>17</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li class="active"><span>19</span></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_19 --> <div id="page_20" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="381"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017APS..DFDF17007D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017APS..DFDF17007D"><span>Large <span class="hlt">eddy</span> simulation of turbine wakes using higher-order methods</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Deskos, Georgios; Laizet, Sylvain; Piggott, Matthew D.; Sherwin, Spencer</p> <p>2017-11-01</p> <p>Large <span class="hlt">eddy</span> simulations (LES) of a horizontal-axis turbine wake are presented using the well-known actuator line (AL) model. The fluid flow is resolved by employing higher-order numerical schemes on a 3D Cartesian mesh combined with a 2D Domain Decomposition strategy for an efficient use of supercomputers. In order to simulate flows at relatively high Reynolds numbers for a reasonable computational cost, a novel strategy is used to introduce controlled numerical dissipation to a selected range of small scales. The idea is to mimic the contribution of the unresolved small-scales by imposing a targeted numerical dissipation at small scales when evaluating the viscous term of the Navier-Stokes equations. The numerical <span class="hlt">technique</span> is shown to behave similarly to the traditional <span class="hlt">eddy</span> viscosity sub-filter scale models such as the classic or the dynamic Smagorinsky models. The results from the simulations are compared to experimental data for a Reynolds number scaled by the diameter equal to ReD =1,000,000 and both the time-averaged stream wise velocity and turbulent kinetic energy (TKE) are showing a good overall agreement. At the end, suggestions for the amount of numerical dissipation required by our approach are made for the particular case of horizontal-axis turbine wakes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://images.nasa.gov/#/details-sl4-137-3608.html','SCIGOVIMAGE-NASA'); return false;" href="https://images.nasa.gov/#/details-sl4-137-3608.html"><span>View of cold water <span class="hlt">eddies</span> in Falkland Current off southern Argentina</span></a></p> <p><a target="_blank" href="https://images.nasa.gov/">NASA Image and Video Library</a></p> <p></p> <p>1973-12-14</p> <p>SL4-137-3608 (14 Dec. 1973) --- A view of cold water <span class="hlt">eddies</span> in the Falkland Current off the South Atlantic coast of southern Argentina as seen from the Skylab space station in Earth orbit. This picture was taken by one of the Skylab 4 crewmen using a hand-held 70mm Hasselblad camera. This land area (left corner) extends south along the coast from Puerto Deseado (center left border) for about 50 miles. Within the ocean, several light blue areas are visible and represent the occurrence of plankton with the Falkland Current. Over the ocean, the cold water <span class="hlt">eddies</span> are identified by the circular cloud-free areas within the cloud street pattern and bordered by cumulus cloud buildup (white). The cloud streets indicate the wind is from the southwest and do not form over <span class="hlt">eddies</span> because energy form the atmosphere is absorbed by the cold ocean water. On the downwind side of the <span class="hlt">eddies</span>, cumulus clouds tend to form as the cold moist air flows over the warmer water. Similar cloud and <span class="hlt">eddy</span> features have been observed by the Skylab 4 crewmen in the Yucatan Current off Yucatan Peninsula and in some parts of the South Pacific. Studies are underway by Dr. George Maul, NOAA, and Dr. Robert Stevenson, ONR, to determine the significance of the cold water <span class="hlt">eddies</span> to ocean dynamics. Photo credit: NASA</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5509091','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5509091"><span>Healing of Fatigue Crack in 1045 Steel by Using <span class="hlt">Eddy</span> Current Treatment</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Yang, Chuan; Xu, Wenchen; Guo, Bin; Shan, Debin; Zhang, Jian</p> <p>2016-01-01</p> <p>In order to investigate the methods to heal fatigue cracks in metals, tubular specimens of 1045 steel with axial and radial fatigue cracks were treated under the <span class="hlt">eddy</span> current. The optical microscope was employed to examine the change of fatigue cracks of specimens before and after the <span class="hlt">eddy</span> current treatment. The results show that the fatigue cracks along the axial direction of the specimen could be healed effectively in the fatigue crack initiation zone and the crack tip zone under the <span class="hlt">eddy</span> current treatment, and the healing could occur within a very short time. The voltage breakdown and the transient thermal compressive stress caused by the detouring of <span class="hlt">eddy</span> current around the fatigue crack were the main factors contributing to the healing in the fatigue crack initiation zone and the crack tip zone, respectively. <span class="hlt">Eddy</span> current treatment may be a novel and effective method for crack healing. PMID:28773761</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28773761','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28773761"><span>Healing of Fatigue Crack in 1045 Steel by Using <span class="hlt">Eddy</span> Current Treatment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Yang, Chuan; Xu, Wenchen; Guo, Bin; Shan, Debin; Zhang, Jian</p> <p>2016-07-29</p> <p>In order to investigate the methods to heal fatigue cracks in metals, tubular specimens of 1045 steel with axial and radial fatigue cracks were treated under the <span class="hlt">eddy</span> current. The optical microscope was employed to examine the change of fatigue cracks of specimens before and after the <span class="hlt">eddy</span> current treatment. The results show that the fatigue cracks along the axial direction of the specimen could be healed effectively in the fatigue crack initiation zone and the crack tip zone under the <span class="hlt">eddy</span> current treatment, and the healing could occur within a very short time. The voltage breakdown and the transient thermal compressive stress caused by the detouring of <span class="hlt">eddy</span> current around the fatigue crack were the main factors contributing to the healing in the fatigue crack initiation zone and the crack tip zone, respectively. <span class="hlt">Eddy</span> current treatment may be a novel and effective method for crack healing.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1915563C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1915563C"><span>Contribution of mesoscale <span class="hlt">eddies</span> to Black Sea ventilation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Capet, Arthur; Mason, Evan; Pascual, Ananda; Grégoire, Marilaure</p> <p>2017-04-01</p> <p>The shoaling of the Black Sea oxycline is one of the most urgent environmental issues in the Black Sea. The permanent oxycline derives directly from the Black Sea permanent stratification and has shoaled alarmingly in the last decades, due to a shifting balance between oxygen consumption and ventilation processes (Capet et al. 2016). The understanding of this balance is thus of the utmost importance and requires to quantify 1) the export of nutrients and organic materials from the shelf regions to the open sea and 2) the ventilation processes. These two processes being influenced by mesoscale features, it is critical to understand the role of the semi-permanent mesoscale structures in horizontal (center/periphery) and vertical (diapycnal and isopycnal) exchanges. A useful insight can be obtained by merging observations from satellite altimeter and in situ profilers (ARGO). In such composite analyses, <span class="hlt">eddies</span> are first automatically identified and tracked from altimeter data (Mason et al. 2014, py-<span class="hlt">eddy</span>-tracker). Vertical ARGO profiles are then expressed in terms of their position relative to <span class="hlt">eddy</span> centers and radii. Derived statistics indicate how consistently mesoscale <span class="hlt">eddies</span> alter the vertical structure, and provide a deeper understanding of the associated horizontal and vertical fluxes. However, this data-based approach is limited in the Black Sea due to the lower quality of gridded altimetric products in the vicinity of the coast, where semi-permanent mesoscale structures prevail. To complement the difficult analysis of this sparse dataset, a compositing methodology. is also applied to model outputs from the 5km GHER-BHAMBI Black Sea implementation (CMEMS BS-MFC). Characteristic biogeochemical anomalies associated with <span class="hlt">eddies</span> in the model are analyzed per se, and compared to the observation-based analysis. Capet, A., Stanev, E. V., Beckers, J.-M., Murray, J. W., and Grégoire, M.: Decline of the Black Sea oxygen inventory, Biogeosciences, 13, 1287-1297, doi:10</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO14B2794R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO14B2794R"><span>Developing an Automated Method for Detection of Operationally Relevant Ocean Fronts and <span class="hlt">Eddies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Rogers-Cotrone, J. D.; Cadden, D. D. H.; Rivera, P.; Wynn, L. L.</p> <p>2016-02-01</p> <p>Since the early 90's, the U.S. Navy has utilized an observation-based process for identification of frontal systems and <span class="hlt">eddies</span>. These Ocean Feature Assessments (OFA) rely on trained analysts to identify and position ocean features using satellite-observed sea surface temperatures. Meanwhile, as enhancements and expansion of the navy's Hybrid Coastal Ocean Model (HYCOM) and Regional Navy Coastal Ocean Model (RNCOM) domains have proceeded, the Naval Oceanographic Office (NAVO) has provided Tactical Oceanographic Feature Assessments (TOFA) that are based on data-validated model output but also rely on analyst identification of significant features. A recently completed project has migrated OFA production to the ArcGIS-based Acoustic Reach-back Cell Ocean Analysis Suite (ARCOAS), enabling use of additional observational datasets and significantly decreasing production time; however, it has highlighted inconsistencies inherent to this analyst-based identification process. Current efforts are focused on development of an automated method for detecting operationally significant fronts and <span class="hlt">eddies</span> that integrates model output and observational data on a global scale. Previous attempts to employ <span class="hlt">techniques</span> from the scientific community have been unable to meet the production tempo at NAVO. Thus, a system that incorporates existing <span class="hlt">techniques</span> (Marr-Hildreth, Okubo-Weiss, etc.) with internally-developed feature identification methods (from model-derived physical and acoustic properties) is required. Ongoing expansions to the ARCOAS toolset have shown promising early results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20160005936','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20160005936"><span>Design and Application of Hybrid Magnetic Field-<span class="hlt">Eddy</span> Current Probe</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wincheski, Buzz; Wallace, Terryl; Newman, Andy; Leser, Paul; Simpson, John</p> <p>2013-01-01</p> <p>The incorporation of magnetic field sensors into <span class="hlt">eddy</span> current probes can result in novel probe designs with unique performance characteristics. One such example is a recently developed electromagnetic probe consisting of a two-channel magnetoresistive sensor with an embedded single-strand <span class="hlt">eddy</span> current inducer. Magnetic flux leakage maps of ferrous materials are generated from the DC sensor response while high-resolution <span class="hlt">eddy</span> current imaging is simultaneously performed at frequencies up to 5 megahertz. In this work the design and optimization of this probe will be presented, along with an application toward analysis of sensory materials with embedded ferromagnetic shape-memory alloy (FSMA) particles. The sensory material is designed to produce a paramagnetic to ferromagnetic transition in the FSMA particles under strain. Mapping of the stray magnetic field and <span class="hlt">eddy</span> current response of the sample with the hybrid probe can thereby image locations in the structure which have experienced an overstrain condition. Numerical modeling of the probe response is performed with good agreement with experimental results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1910264Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1910264Y"><span>Description of the Lofoten Basin <span class="hlt">Eddy</span> using three years of Seaglider observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Lusha; Bosse, Anthony; Fer, Ilker; Arild Orvik, Kjell; Magnus Bruvik, Erik; Hessevik, Idar; Kvalsund, Karsten</p> <p>2017-04-01</p> <p>The Lofoten Basin of the Norwegian Sea is an area where the warm Atlantic Water is subject to the greatest heat losses anywhere in the Nordic Seas. The region is recognized as an area of intense mesoscale activity, including <span class="hlt">eddies</span> shed from the Norwegian slope current and a long-lived, deep, anticyclonic <span class="hlt">eddy</span> residing in the central part of the basin (the Lofoten Basin <span class="hlt">Eddy</span>, LBE). Here we use observations from Seagliders, collected in five missions between July 2012 and April 2015, to describe the LBE in unprecedented detail. The missions were concentrated to sample the LBE repeatedly, allowing for multiple realizations of radial sections across the <span class="hlt">eddy</span>. The LBE has a mean radius of 18 ± 4 km, and propagates cyclonically with a mean speed of approximately 3-4 cm s-1. The anticyclonic azimuthal peak velocity varies between 0.5 and 0.7 m s-1, located between 680 and 860 m depth, and 16 and 25 km radial distance to the <span class="hlt">eddy</span> center. The contribution of geostrophy in the cyclogeostrophic balance is approximately 50%, which indicates the importance of the non-linear effects. The relative vorticity representative of the core exhibits large values between -0.7f to -0.9f, where f is the local Coriolis parameter. The <span class="hlt">eddy</span> core is long-lived (at least two years from May 2013 to March 2015), has characteristic values of Conservative Temperature of 4.8°C and Absolute Salinity of 35.34 g kg-1, and deepens to approximately 730 m in wintertime. A comparison of the <span class="hlt">eddy</span> properties to those inferred from automated tracking of satellite altimeter observations shows that while the location of <span class="hlt">eddy</span> center is detected accurately to within 5 km, the altimeter inferred vorticity is underestimated and the radius overestimated, each approximately by a factor of 2, because of excessive smoothing relative to the small <span class="hlt">eddy</span> radius.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/ED086442.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/ED086442.pdf"><span>Nondestructive Testing <span class="hlt">Eddy</span> Current Basic Principles RQA/M1-5330.12 (V-I).</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.</p> <p></p> <p>As one in the series of programmed instruction handbooks, prepared by the U.S. space program, home study material is presented in this volume concerning familiarization and orientation on basic <span class="hlt">eddy</span> current principles. The subject is presented under the following headings: Basic <span class="hlt">Eddy</span> Current Concepts, <span class="hlt">Eddy</span> Current Generation and Distribution,…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1408588','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1408588"><span>Continuum Modeling of Inductor Hysteresis and <span class="hlt">Eddy</span> Current Loss Effects in Resonant Circuits</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Pries, Jason L.; Tang, Lixin; Burress, Timothy A.</p> <p></p> <p>This paper presents experimental validation of a high-fidelity toroid inductor modeling <span class="hlt">technique</span>. The aim of this research is to accurately model the instantaneous magnetization state and core losses in ferromagnetic materials. Quasi–static hysteresis effects are captured using a Preisach model. <span class="hlt">Eddy</span> currents are included by coupling the associated quasi-static Everett function to a simple finite element model representing the inductor cross sectional area. The modeling <span class="hlt">technique</span> is validated against the nonlinear frequency response from two different series RLC resonant circuits using inductors made of electrical steel and soft ferrite. The method is shown to accurately model shifts in resonant frequencymore » and quality factor. The <span class="hlt">technique</span> also successfully predicts a discontinuity in the frequency response of the ferrite inductor resonant circuit.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.6814Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.6814Y"><span>The Lofoten Basin <span class="hlt">eddy</span>: Three years of evolution as observed by Seagliders</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, Lu-Sha; Bosse, Anthony; Fer, Ilker; Orvik, Kjell A.; Bruvik, Erik M.; Hessevik, Idar; Kvalsund, Karsten</p> <p>2017-08-01</p> <p>The Lofoten Basin in the Norwegian Sea is an area where the warm Atlantic Water is subject to the greatest heat losses anywhere in the Nordic Seas. A long-lived, deep, anticyclonic <span class="hlt">eddy</span> is located in the central part of the basin (the Lofoten Basin <span class="hlt">Eddy</span>, LBE). Here we use observations from Seagliders, collected between July 2012 and July 2015, to describe LBE in unprecedented detail. The missions were designed to sample LBE repeatedly, allowing for multiple realizations of radial sections across the <span class="hlt">eddy</span>. LBE has a mean radius of 18 ± 4 km and propagates cyclonically with a mean speed of approximately 3-4 cm s-1. The anticyclonic azimuthal peak velocity varies between 0.5 and 0.7 m s-1, located between 700 and 900 m depth. The average contribution of geostrophy in the cyclogeostrophic balance is 44%. The relative vorticity of the core is close to the local Coriolis parameter. The evolution of core water properties shows substantial interannual variability, influenced by surface buoyancy flux and advection of anomalous low-salinity near-surface waters that may affect the vertical extent of winter convection. A comparison of the <span class="hlt">eddy</span> properties to those inferred from automated tracking of satellite altimeter observations shows that the location of <span class="hlt">eddy</span> center is successfully detected to within one half <span class="hlt">eddy</span> radius, but vorticity is underestimated and the radius overestimated, each approximately by a factor of 2, because of excessive smoothing relative to the small <span class="hlt">eddy</span> radius.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840019098','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840019098"><span>Review of <span class="hlt">correlation</span> <span class="hlt">techniques</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bowhill, S. A.</p> <p>1983-01-01</p> <p><span class="hlt">Correlation</span> analysis in MST radar to determine the scattered power, Doppler frequency and <span class="hlt">correlation</span> time for a noisy signal is examined. It is assumed that coherent detection was employed, with two accurately balanced quadrature receiving channels and that coherent integration is performed with a window length significantly less than the <span class="hlt">correlation</span> time of the signal.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AGUFM.A43J..05Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AGUFM.A43J..05Z"><span>On the Roles of Upper- versus Lower-level Thermal Forcing in Shifting the <span class="hlt">Eddy</span>-Driven Jet</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Y.; Nie, Y.; Chen, G.; Yang, X. Q.</p> <p>2017-12-01</p> <p>One most drastic atmospheric change in the global warming scenario is the increase in temperature over tropical upper-troposphere and polar surface. The strong warming over those two area alters the spacial distributions of the baroclinicity in the upper-troposphere of subtropics and in the lower-level of subpolar region, with competing effects on the mid-latitude atmospheric circulation. The final destination of the <span class="hlt">eddy</span>-driven jet in future climate could be "a tug of war" between the impacts of such upper- versus lower-level thermal forcing. In this study, the roles of upper- versus lower-level thermal forcing in shifting the <span class="hlt">eddy</span>-driven jet are investigated using a nonlinear multi-level quasi-geostrophic channel model. All of our sensitivity experiments show that the latitudinal position of the <span class="hlt">eddy</span>-driven jet is more sensitive to the upper-level thermal forcing. Such upper-level dominance over the lower-level forcing can be attributed to the different mechanisms through which <span class="hlt">eddy</span>-driven jet responses to them. The upper-level thermal forcing induces a jet shift mainly by affecting the baroclinic generation of <span class="hlt">eddies</span>, which supports the latitudinal shift of the <span class="hlt">eddy</span> momentum flux convergence. The jet response to the lower-level thermal forcing, however, is strongly "<span class="hlt">eddy</span> dissipation control". The lower-level forcing, by changing the baroclinicity in the lower troposphere, induces a direct thermal zonal wind response in the upper level thus modifies the nonlinear wave breaking and the resultant irreversible <span class="hlt">eddy</span> mixing, which amplifies the latitudinal shift of the <span class="hlt">eddy</span>-driven jet. Whether the <span class="hlt">eddy</span> response is "generation control" or "dissipation control" may strongly depend on the <span class="hlt">eddy</span> behavior in its baroclinic processes. Only the anomalous <span class="hlt">eddy</span> generation that penetrates into the upper troposphere can have a striking impact on the <span class="hlt">eddy</span> momentum flux, which pushes the jet shift more efficiently and dominates the <span class="hlt">eddy</span> response.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://files.eric.ed.gov/fulltext/EJ1079867.pdf','ERIC'); return false;" href="http://files.eric.ed.gov/fulltext/EJ1079867.pdf"><span>Interview with <span class="hlt">Eddie</span> Reisch</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>Owen, Hazel</p> <p>2013-01-01</p> <p><span class="hlt">Eddie</span> Reisch is currently working as a policy advisor for Te Reo Maori Operational Policy within the Student Achievement group with the Ministry of Education in New Zealand, where he has implemented and led a range of e-learning initiatives and developments, particularly the Virtual Learning Network (VLN). He is regarded as one of the leading…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22263747-scanning-tone-burst-eddy-current-thermography-tbet-ndt-carbon-fiber-reinforced-plastic-cfrp-components','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22263747-scanning-tone-burst-eddy-current-thermography-tbet-ndt-carbon-fiber-reinforced-plastic-cfrp-components"><span>Scanning tone burst <span class="hlt">eddy</span>-current thermography (S-TBET) for NDT of carbon fiber reinforced plastic (CFRP) components</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Libin, M. N.; Maxfield, B. W.; Balasubramanian, Krishnan</p> <p>2014-02-18</p> <p>Tone Burst <span class="hlt">Eddy</span> Current <span class="hlt">technique</span> uses <span class="hlt">eddy</span> current to apply transient heating inside a component and uses a conventional IR camera for visualization of the response to the transient heating. This <span class="hlt">technique</span> has been earliest demonstrated for metallic components made of AL, Steel, Stainless Steel, etc., and for detection of cracks, corrosion and adhesive dis-bonds. Although, not nearly as conducting as metals, the Carbon Fibre Reinforced Plastic (CFRP) material absorbs measurable electromagnetic radiation in the frequency range above 10 kHz. When the surface temperature is observed on the surface that is being heated (defined as the surface just beneath andmore » slightly to one side of the heating coil), the surface temperature increases with increasing frequency because the internal heating increases with frequency. A 2-D anisotropic transient <span class="hlt">Eddy</span> current heating and thermal conduction model has been developed that provides a reasonable description of the processes described above. The inherent anisotropy of CFRP laminates is included in this model by calculating the heating due to three superimposed, tightly coupled isotropic layers having a specified ply-layup. The experimental apparatus consists of an induction heating coil and an IR camera with low NETD and high frame rates. The coil is moved over the sample using a stepper motor controlled manipulator. The IR data recording is synchronized with the motion control to provide a movie of the surface temperature over time. Several components were evaluated for detection of impact damage, location of stiffeners, etc. on CFRP components.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1235541-turbulent-eddies-compressible-jet-crossflow-measured-using-pulse-burst-particle-image-velocimetry','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1235541-turbulent-eddies-compressible-jet-crossflow-measured-using-pulse-burst-particle-image-velocimetry"><span>Turbulent <span class="hlt">eddies</span> in a compressible jet in crossflow measured using pulse-burst particle image velocimetry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Beresh, Steven J.; Wagner, Justin L.; Henfling, John F.; ...</p> <p>2016-01-01</p> <p>Pulse-burst Particle Image Velocimetry(PIV) has been employed to acquire time-resolved data at 25 kHz of a supersonic jet exhausting into a subsonic compressible crossflow. Data were acquired along the windward boundary of the jet shear layer and used to identify turbulenteddies as they convect downstream in the far-field of the interaction. <span class="hlt">Eddies</span> were found to have a tendency to occur in closely spaced counter-rotating pairs and are routinely observed in the PIV movies, but the variable orientation of these pairs makes them difficult to detect statistically. <span class="hlt">Correlated</span> counter-rotating vortices are more strongly observed to pass by at a larger spacing,more » both leading and trailing the reference <span class="hlt">eddy</span>. This indicates the paired nature of the turbulenteddies and the tendency for these pairs to recur at repeatable spacing. Velocity spectra reveal a peak at a frequency consistent with this larger spacing between shear-layer vortices rotating with identical sign. The spatial scale of these vortices appears similar to previous observations of compressible jets in crossflow. Furthermore,super-sampled velocity spectra to 150 kHz reveal a power-law dependency of –5/3 in the inertial subrange as well as a –1 dependency at lower frequencies attributed to the scales of the dominant shear-layer <span class="hlt">eddies</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1235541','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/1235541"><span>Turbulent <span class="hlt">eddies</span> in a compressible jet in crossflow measured using pulse-burst particle image velocimetry</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Beresh, Steven J.; Wagner, Justin L.; Henfling, John F.</p> <p></p> <p>Pulse-burst Particle Image Velocimetry(PIV) has been employed to acquire time-resolved data at 25 kHz of a supersonic jet exhausting into a subsonic compressible crossflow. Data were acquired along the windward boundary of the jet shear layer and used to identify turbulenteddies as they convect downstream in the far-field of the interaction. <span class="hlt">Eddies</span> were found to have a tendency to occur in closely spaced counter-rotating pairs and are routinely observed in the PIV movies, but the variable orientation of these pairs makes them difficult to detect statistically. <span class="hlt">Correlated</span> counter-rotating vortices are more strongly observed to pass by at a larger spacing,more » both leading and trailing the reference <span class="hlt">eddy</span>. This indicates the paired nature of the turbulenteddies and the tendency for these pairs to recur at repeatable spacing. Velocity spectra reveal a peak at a frequency consistent with this larger spacing between shear-layer vortices rotating with identical sign. The spatial scale of these vortices appears similar to previous observations of compressible jets in crossflow. Furthermore,super-sampled velocity spectra to 150 kHz reveal a power-law dependency of –5/3 in the inertial subrange as well as a –1 dependency at lower frequencies attributed to the scales of the dominant shear-layer <span class="hlt">eddies</span>.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017NatSR...746218G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017NatSR...746218G"><span>An Intrathermocline <span class="hlt">Eddy</span> and a tropical cyclone in the Bay of Bengal</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gordon, Arnold L.; Shroyer, Emily; Murty, V. S. N.</p> <p>2017-04-01</p> <p>The Bay of Bengal, subjected to monsoonal forcing and tropical cyclones, displays a complex field of ocean <span class="hlt">eddies</span>. On 5 December 2013 a sub-surface vortex or Intrathermocline <span class="hlt">Eddy</span> (ITE) composed of water characteristic of the Andaman Sea was observed within the thermocline of the western Bay of Bengal. We propose that the ITE was the product of Tropical Cyclone Lehar interaction on 27 November 2013 with a westward propagating surface <span class="hlt">eddy</span> from the eastern Bay of Bengal. While Lehar’s interaction with the ocean initially removes heat from the upper layers of the <span class="hlt">eddy</span>, air-sea flux is limited as the deeper portions of the <span class="hlt">eddy</span> was subducted into the stratified thermocline, inhibiting further interaction with the atmosphere. The ITE core from 30 to 150 m is thus isolated from local air-sea fluxes by strong stratification at the mixed layer base, and its periphery is stable to shear instability, suggestive of longevity and the ability to carry water far distances with minimal modification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/28401909','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/28401909"><span>An Intrathermocline <span class="hlt">Eddy</span> and a tropical cyclone in the Bay of Bengal.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Gordon, Arnold L; Shroyer, Emily; Murty, V S N</p> <p>2017-04-12</p> <p>The Bay of Bengal, subjected to monsoonal forcing and tropical cyclones, displays a complex field of ocean <span class="hlt">eddies</span>. On 5 December 2013 a sub-surface vortex or Intrathermocline <span class="hlt">Eddy</span> (ITE) composed of water characteristic of the Andaman Sea was observed within the thermocline of the western Bay of Bengal. We propose that the ITE was the product of Tropical Cyclone Lehar interaction on 27 November 2013 with a westward propagating surface <span class="hlt">eddy</span> from the eastern Bay of Bengal. While Lehar's interaction with the ocean initially removes heat from the upper layers of the <span class="hlt">eddy</span>, air-sea flux is limited as the deeper portions of the <span class="hlt">eddy</span> was subducted into the stratified thermocline, inhibiting further interaction with the atmosphere. The ITE core from 30 to 150 m is thus isolated from local air-sea fluxes by strong stratification at the mixed layer base, and its periphery is stable to shear instability, suggestive of longevity and the ability to carry water far distances with minimal modification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/15298408','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/15298408"><span>Phase demodulation from a single fringe pattern based on a <span class="hlt">correlation</span> <span class="hlt">technique</span>.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Robin, Eric; Valle, Valéry</p> <p>2004-08-01</p> <p>We present a method for determining the demodulated phase from a single fringe pattern. This method, based on a <span class="hlt">correlation</span> <span class="hlt">technique</span>, searches in a zone of interest for the degree of similarity between a real fringe pattern and a mathematical model. This method, named modulated phase <span class="hlt">correlation</span>, is tested with different examples.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_18");'>18</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li class="active"><span>20</span></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_20 --> <div id="page_21" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="401"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20050205852','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20050205852"><span>Novel Optical <span class="hlt">Technique</span> Developed and Tested for Measuring Two-Point Velocity <span class="hlt">Correlations</span> in Turbulent Flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zimmerli, Gregory A.; Goldburg, Walter I.</p> <p>2002-01-01</p> <p>A novel <span class="hlt">technique</span> for characterizing turbulent flows was developed and tested at the NASA Glenn Research Center. The work is being done in collaboration with the University of Pittsburgh, through a grant from the NASA Microgravity Fluid Physics Program. The <span class="hlt">technique</span> we are using, Homodyne <span class="hlt">Correlation</span> Spectroscopy (HCS), is a laser-light-scattering <span class="hlt">technique</span> that measures the Doppler frequency shift of light scattered from microscopic particles in the fluid flow. Whereas Laser Doppler Velocimetry gives a local (single-point) measurement of the fluid velocity, the HCS <span class="hlt">technique</span> measures <span class="hlt">correlations</span> between fluid velocities at two separate points in the flow at the same instant of time. Velocity <span class="hlt">correlations</span> in the flow field are of fundamental interest to turbulence researchers and are of practical importance in many engineering applications, such as aeronautics.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016JGRC..121.3517L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016JGRC..121.3517L"><span>Dynamical analysis of a satellite-observed anticyclonic <span class="hlt">eddy</span> in the northern Bering Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Li, Yineng; Li, Xiaofeng; Wang, Jia; Peng, Shiqiu</p> <p>2016-05-01</p> <p>The characteristics and evolution of a satellite-observed anticyclonic <span class="hlt">eddy</span> in the northern Bering Sea during March and April 1999 are investigated using a three-dimensional Princeton Ocean Model (POM). The anticyclonic-like current pattern and asymmetric feature of the <span class="hlt">eddy</span> were clearly seen in the synthetic aperture radar (SAR), sea surface temperature, and ocean color images in April 1999. The results from model simulation reveal the three-dimensional structure of the anticyclonic <span class="hlt">eddy</span>, its movement, and dissipation. Energy analysis indicates that the barotropic instability (BTI) is the main energy source for the growth of the anticyclonic <span class="hlt">eddy</span>. The momentum analysis further reveals that the larger magnitude of the barotropic pressure gradient in the meridional direction causes the asymmetry of the anticyclonic <span class="hlt">eddy</span> in the zonal and meridional directions, while the different magnitudes of the meridional baroclinic pressure gradient are responsible for the different intensity of currents between the northern and southern parts of the anticyclonic <span class="hlt">eddy</span>. This article was corrected on 23 JUL 2016. See the end of the full text for details.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.8763F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.8763F"><span>Effect of mesoscale oceanic <span class="hlt">eddies</span> on mid-latitude storm-tracks.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Foussard, Alexis; Lapeyre, Guillaume; Plougonven, Riwal</p> <p>2017-04-01</p> <p>Sharp sea surface temperature (SST) gradients associated with oceanic western boundary currents (WBC) exert an influence on the position and intensity of mid-latitude storm-tracks. This occurs through strong surface baroclinicity maintained by cross frontal SST gradient and deep vertical atmospheric motion due to convection on the warm flank of the WBC. However the additional role of mesoscale oceanic structures (30-300km) has not yet been explored although they have a non-negligible influence on surface heat fluxes. Using the Weather Research and Forecasting model, we investigate the potential role of these oceanic <span class="hlt">eddies</span> in the case of an idealized atmospheric mid-latitude storm track forced by a mesoscale oceanic <span class="hlt">eddy</span> field superposed with a large-scale SST gradient. Surface latent and sensible fluxes are shown to react with a non-linear response to the SST variations, providing additional heat and moisture supply at large scales. The atmospheric response is not restricted to the boundary layer but reaches the free troposphere, especially through increased water vapor vertical transport and latent heat release. This additional heating in presence of <span class="hlt">eddies</span> is balanced by a shift of the storm-track and its poleward heat flux toward high latitudes, with amplitude depending on atmospheric configuration and <span class="hlt">eddies</span> amplitude. We also explore how this displacement of perturbations changes the position and structure of the mid-latitude jet through <span class="hlt">eddy</span> momentum fluxes.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012EGUGA..14..858K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012EGUGA..14..858K"><span>Role of mesoscale <span class="hlt">eddies</span> on exchanges between coastal regions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kersalé, M.; Petrenko, A. A.; Doglioli, A. M.; Nencioli, F.; Bouffard, J.; Dekeyser, I.</p> <p>2012-04-01</p> <p>The general circulation in the northwestern Mediterranean Sea is characterized by a cyclonic circulation. The northern part of this gyre is formed by the Northern Current (NC), which flows along the continental slope from the Ligurian Sea towards the Catalan Shelf. The NC has an important influence on the Gulf of Lion (GoL), a large continental margin in the northern part of the basin. The NC constitutes an effective dynamical barrier which blocks coastal waters on the continental shelf. The western part of the GoL is a key region for regulating the outflow from the continental shelf to the Catalan Basin. These exchanges are mainly induced by partially ageostrophic processes originating from the interaction between the NC and mesoscale activity like meanders, filaments and <span class="hlt">eddies</span>. Both GoL and Catalan shelf are characterized by an intense mesoscale activity. <span class="hlt">Eddies</span> in the GoL are baroclinic structures extending throughout the mixed layer (30 to 50m), often elliptic in shape and about 20-30km in diameter. Catalan <span class="hlt">eddies</span> are characterized by a vertical extension between 70 and 100m and a diameter of about 45km. The LAgrangian Transport EXperiment (LATEX, 2008-2011) was designed to study the mechanisms of formation of anticyclones in the western part of the GoL and their influence on cross-shelf exchanges. Mesoscale anticyclones have been observed in the western part of the GoL and over the Catalan shelf by the combined use of data from satellite observations, in situ measurements and numerical modeling. Recent numerical experiments show an anticyclonic circulation extending over a large part of the coastal area (latitudinal range : 41°50' to 43°N ; longitudinal range : 3°10' to 4°10'E). Interaction with a meander of the NC induces the separation of this circulation in two different <span class="hlt">eddies</span>, one in the GoL and the other in the Catalan shelf. These <span class="hlt">eddies</span> exhibit strong interaction between them, resulting in important exchanges between the two coastal regions. On</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS53A1009H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS53A1009H"><span>Stochastic Ocean <span class="hlt">Eddy</span> Perturbations in a Coupled General Circulation Model.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Howe, N.; Williams, P. D.; Gregory, J. M.; Smith, R. S.</p> <p>2014-12-01</p> <p>High-resolution ocean models, which are <span class="hlt">eddy</span> permitting and resolving, require large computing resources to produce centuries worth of data. Also, some previous studies have suggested that increasing resolution does not necessarily solve the problem of unresolved scales, because it simply introduces a new set of unresolved scales. Applying stochastic parameterisations to ocean models is one solution that is expected to improve the representation of small-scale (<span class="hlt">eddy</span>) effects without increasing run-time. Stochastic parameterisation has been shown to have an impact in atmosphere-only models and idealised ocean models, but has not previously been studied in ocean general circulation models. Here we apply simple stochastic perturbations to the ocean temperature and salinity tendencies in the low-resolution coupled climate model, FAMOUS. The stochastic perturbations are implemented according to T(t) = T(t-1) + (ΔT(t) + ξ(t)), where T is temperature or salinity, ΔT is the corresponding deterministic increment in one time step, and ξ(t) is Gaussian noise. We use high-resolution HiGEM data coarse-grained to the FAMOUS grid to provide information about the magnitude and spatio-temporal <span class="hlt">correlation</span> structure of the noise to be added to the lower resolution model. Here we present results of adding white and red noise, showing the impacts of an additive stochastic perturbation on mean climate state and variability in an AOGCM.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4247373','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4247373"><span>Electrically generated <span class="hlt">eddies</span> at an eightfold stagnation point within a nanopore</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Sherwood, J. D.; Mao, M.; Ghosal, S.</p> <p>2014-01-01</p> <p>Electrically generated flows around a thin dielectric plate pierced by a cylindrical hole are computed numerically. The geometry represents that of a single nanopore in a membrane. When the membrane is uncharged, flow is due solely to induced charge electroosmosis, and <span class="hlt">eddies</span> are generated by the high fields at the corners of the nanopore. These <span class="hlt">eddies</span> meet at stagnation points. If the geometry is chosen correctly, the stagnation points merge to form a single stagnation point at which four streamlines cross at a point and eight <span class="hlt">eddies</span> meet. PMID:25489206</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4740428','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4740428"><span>Observing mesoscale <span class="hlt">eddy</span> effects on mode-water subduction and transport in the North Pacific</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xu, Lixiao; Li, Peiliang; Xie, Shang-Ping; Liu, Qinyu; Liu, Cong; Gao, Wendian</p> <p>2016-01-01</p> <p>While modelling studies suggest that mesoscale <span class="hlt">eddies</span> strengthen the subduction of mode waters, this <span class="hlt">eddy</span> effect has never been observed in the field. Here we report results from a field campaign from March 2014 that captured the <span class="hlt">eddy</span> effects on mode-water subduction south of the Kuroshio Extension east of Japan. The experiment deployed 17 Argo floats in an anticyclonic <span class="hlt">eddy</span> (AC) with enhanced daily sampling. Analysis of over 3,000 hydrographic profiles following the AC reveals that potential vorticity and apparent oxygen utilization distributions are asymmetric outside the AC core, with enhanced subduction near the southeastern rim of the AC. There, the southward <span class="hlt">eddy</span> flow advects newly ventilated mode water from the north into the main thermocline. Our results show that subduction by <span class="hlt">eddy</span> lateral advection is comparable in magnitude to that by the mean flow—an effect that needs to be better represented in climate models. PMID:26829888</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4801610','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4801610"><span>Detection and Inspection of Steel Bars in Reinforced Concrete Structures Using Active Infrared Thermography with Microwave Excitation and <span class="hlt">Eddy</span> Current Sensors</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Szymanik, Barbara; Frankowski, Paweł Karol; Chady, Tomasz; John Chelliah, Cyril Robinson Azariah</p> <p>2016-01-01</p> <p>The purpose of this paper is to present a multi-sensor approach to the detection and inspection of steel bars in reinforced concrete structures. In connection with our past experience related to non-destructive testing of different materials, we propose using two potentially effective methods: active infrared thermography with microwave excitation and the <span class="hlt">eddy</span> current <span class="hlt">technique</span>. In this article active infrared thermography with microwave excitation is analyzed both by numerical modeling and experiments. This method, based on thermal imaging, due to its characteriatics should be considered as a preliminary method for the assessment of relatively shallowly located steel bar reinforcements. The <span class="hlt">eddy</span> current <span class="hlt">technique</span>, on the other hand, allows for more detailed evaluation and detection of deeply located rebars. In this paper a series of measurement results, together with the initial identification of certain features of steel reinforcement bars will be presented. PMID:26891305</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.5186H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.5186H"><span>Automated detection of Lagrangian <span class="hlt">eddies</span> and coherent transport of heat and salinity in the Agulhas leakage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Huhn, Florian; Haller, George</p> <p>2014-05-01</p> <p>Haller and Beron-Vera(2013) have recently introduced a new objective method to detect coherent Lagrangian <span class="hlt">eddies</span> in turbulence. They find that closed null-geodesics of a generalized Green-Lagrange strain tensor act as coherent Lagrangian <span class="hlt">eddy</span> boundaries, showing near-zero and uniform material stretching. We make use of this method to develop an automated detection procedure for coherent Lagrangian <span class="hlt">eddies</span> in large-scale ocean data. We apply our results to a recent 3D general circulation model, the Southern Ocean State Estimate (SOSE), with focus on the South Atlantic Ocean and the inter-ocean exchange between the Indian and Atlantic ocean. We detect a large number of coherent Lagrangian <span class="hlt">eddies</span> and present statistics of their properties. The largest and most circular <span class="hlt">eddy</span> boundaries represent Lagrangian Agulhas rings. Circular regions inside these rings with higher temperature and salinity than the surrounding waters can be explained by the coherent <span class="hlt">eddy</span> boundaries that enclose and isolate the <span class="hlt">eddy</span> interiors. We compare <span class="hlt">eddy</span> boundaries at different depths with <span class="hlt">eddy</span> boundaries obtained from geostrophic velocities derived from the model's sea surface height (SSH). The transport of mass, heat and salinity enclosed by coherent <span class="hlt">eddies</span> through a section in the Cape basin is quantified and compared to the non-coherent transport by the background flow.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018ClDy..tmp...26L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018ClDy..tmp...26L"><span>Response of <span class="hlt">eddy</span> activities to localized diabatic heating in Held-Suarez simulations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lin, Yanluan; Zhang, Jishi; Li, Xingrui; Deng, Yi</p> <p>2018-01-01</p> <p>Widespread air pollutions, such as black carbon over East Asia in recent years, could induce a localized diabatic heating, and thus lead to localized static stability and meridional temperature gradient (MTG) changes. Although effect of static stability and MTG on <span class="hlt">eddies</span> has been addressed by the linear baroclinic instability theory, impacts of a localized heating on mid-latitude <span class="hlt">eddy</span> activities have not been well explored and quantified. Via a series of idealized global Held-Suarez simulations with different magnitudes of localized heating at different altitudes and latitudes, responses of mid-latitude <span class="hlt">eddy</span> activity and circulation to these temperature perturbations are systematically investigated. Climatologically, the localized heating in the lower atmosphere induces a wave-like response of <span class="hlt">eddy</span> activity near the mid-latitude jet stream. Over the heating region, <span class="hlt">eddy</span> activity tends to be weakening due to the increased static stability. However, there are cyclonic anomalies over the upstream and downstream of the heating region. The zonal mean <span class="hlt">eddy</span> activity weakens along the baroclinic zone due to reduced MTG and increased static stability. Furthermore, the response of <span class="hlt">eddy</span> activity increased as the heating magnitude is increased and moved to higher altitudes. The influence of the heating decreases as the heating is prescribed further away from the climatological mid-latitude jet. This implies that the localized heating is most effective over the region with the maximum baroclinicity. Besides, enhanced storm track downstream of the localized heating area found here suggests that increased aerosols over East Asia might strengthen the North Pacific storm track.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.3964S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.3964S"><span>Characterizing frontal <span class="hlt">eddies</span> along the East Australian Current from HF radar observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Schaeffer, Amandine; Gramoulle, A.; Roughan, M.; Mantovanelli, A.</p> <p>2017-05-01</p> <p>The East Australian Current (EAC) dominates the ocean circulation along south-eastern Australia, however, little is known about the submesoscale frontal instabilities associated with this western boundary current. One year of surface current measurements from HF radars, in conjunction with mooring and satellite observations, highlight the occurrence and propagation of meanders and frontal <span class="hlt">eddies</span> along the inshore edge of the EAC. <span class="hlt">Eddies</span> were systematically identified using the geometry of the high spatial resolution (˜1.5 km) surface currents, and tracked every hour. Cyclonic <span class="hlt">eddies</span> were observed irregularly, on average every 7 days, with inshore radius ˜10 km. Among various forms of structures, frontal <span class="hlt">eddies</span> associated with EAC meanders were characterized by poleward advection speeds of ˜0.3-0.4 m/s, migrating as far as 500 km south, based on satellite imagery. Flow field kinematics show that cyclonic <span class="hlt">eddies</span> have high Rossby numbers (0.6-1.9) and enhance particle dispersion. Patches of intensified surface divergence at the leading edge of the structures are expected to generate vertical uplift. This is confirmed by subsurface measurements showing temperature uplift of up to 55 m over 24 h and rough estimates of vertical velocities of 10s of meters per day. While frontal <span class="hlt">eddies</span> propagate through the radar domain independently of local wind stress, upfront wind can influence their stalling and growth, and can also generate large cold core <span class="hlt">eddies</span> through intense shear. Such coherent structures are a major mechanism for the transport and entrainment of nutrient rich coastal or deep waters, influencing physical and biological dynamics, and connectivity over large distances.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018OcMod.124....1P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018OcMod.124....1P"><span>Parameterized and resolved Southern Ocean <span class="hlt">eddy</span> compensation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Poulsen, Mads B.; Jochum, Markus; Nuterman, Roman</p> <p>2018-04-01</p> <p>The ability to parameterize Southern Ocean <span class="hlt">eddy</span> effects in a forced coarse resolution ocean general circulation model is assessed. The transient model response to a suite of different Southern Ocean wind stress forcing perturbations is presented and compared to identical experiments performed with the same model in 0.1° <span class="hlt">eddy</span>-resolving resolution. With forcing of present-day wind stress magnitude and a thickness diffusivity formulated in terms of the local stratification, it is shown that the Southern Ocean residual meridional overturning circulation in the two models is different in structure and magnitude. It is found that the difference in the upper overturning cell is primarily explained by an overly strong subsurface flow in the parameterized <span class="hlt">eddy</span>-induced circulation while the difference in the lower cell is mainly ascribed to the mean-flow overturning. With a zonally constant decrease of the zonal wind stress by 50% we show that the absolute decrease in the overturning circulation is insensitive to model resolution, and that the meridional isopycnal slope is relaxed in both models. The agreement between the models is not reproduced by a 50% wind stress increase, where the high resolution overturning decreases by 20%, but increases by 100% in the coarse resolution model. It is demonstrated that this difference is explained by changes in surface buoyancy forcing due to a reduced Antarctic sea ice cover, which strongly modulate the overturning response and ocean stratification. We conclude that the parameterized <span class="hlt">eddies</span> are able to mimic the transient response to altered wind stress in the high resolution model, but partly misrepresent the unperturbed Southern Ocean meridional overturning circulation and associated heat transports.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/21106418','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/21106418"><span>Finite element analysis of gradient z-coil induced <span class="hlt">eddy</span> currents in a permanent MRI magnet.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, Xia; Xia, Ling; Chen, Wufan; Liu, Feng; Crozier, Stuart; Xie, Dexin</p> <p>2011-01-01</p> <p>In permanent magnetic resonance imaging (MRI) systems, pulsed gradient fields induce strong <span class="hlt">eddy</span> currents in the conducting structures of the magnet body. The gradient field for image encoding is perturbed by these <span class="hlt">eddy</span> currents leading to MR image distortions. This paper presents a comprehensive finite element (FE) analysis of the <span class="hlt">eddy</span> current generation in the magnet conductors. In the proposed FE model, the hysteretic characteristics of ferromagnetic materials are considered and a scalar Preisach hysteresis model is employed. The developed FE model was applied to study gradient z-coil induced <span class="hlt">eddy</span> currents in a 0.5 T permanent MRI device. The simulation results demonstrate that the approach could be effectively used to investigate <span class="hlt">eddy</span> current problems involving ferromagnetic materials. With the knowledge gained from this <span class="hlt">eddy</span> current model, our next step is to design a passive magnet structure and active gradient coils to reduce the <span class="hlt">eddy</span> current effects. Copyright © 2010 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22113500-eddy-current-nde-performance-demonstrations-using-simulation-tools','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22113500-eddy-current-nde-performance-demonstrations-using-simulation-tools"><span><span class="hlt">Eddy</span> current NDE performance demonstrations using simulation tools</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Maurice, L.; Costan, V.; Guillot, E.</p> <p>2013-01-25</p> <p>To carry out performance demonstrations of the <span class="hlt">Eddy</span>-Current NDE processes applied on French nuclear power plants, EDF studies the possibility of using simulation tools as an alternative to measurements on steam generator tube mocks-up. This paper focuses on the strategy led by EDF to assess and use code{sub C}armel3D and Civa, on the case of <span class="hlt">Eddy</span>-Current NDE on wears problem which may appear in the U-shape region of steam generator tubes due to the rubbing of anti-vibration bars.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003IJCFD..17..433C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003IJCFD..17..433C"><span>Detached-<span class="hlt">Eddy</span> Simulations of Attached and Detached Boundary Layers</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Caruelle, B.; Ducros, F.</p> <p>2003-12-01</p> <p>This article presents Detached-<span class="hlt">Eddy</span> Simulations (DESs) of attached and detached turbulent boundary layers. This hybrid Reynolds Averaged Navier-Stokes (RANS) / Large <span class="hlt">Eddy</span> Simulation (LES) model goes continuously from RANS to LES according to the mesh definition. We propose a parametric study of the model over two "academic" configurations, in order to get information on the influence of the mesh to correctly treat complex flow with attached and detached boundary layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..19.3663W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..19.3663W"><span>Improved Climate Simulations through a Stochastic Parameterization of Ocean <span class="hlt">Eddies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Williams, Paul; Howe, Nicola; Gregory, Jonathan; Smith, Robin; Joshi, Manoj</p> <p>2017-04-01</p> <p>In climate simulations, the impacts of the subgrid scales on the resolved scales are conventionally represented using deterministic closure schemes, which assume that the impacts are uniquely determined by the resolved scales. Stochastic parameterization relaxes this assumption, by sampling the subgrid variability in a computationally inexpensive manner. This study shows that the simulated climatological state of the ocean is improved in many respects by implementing a simple stochastic parameterization of ocean <span class="hlt">eddies</span> into a coupled atmosphere-ocean general circulation model. Simulations from a high-resolution, <span class="hlt">eddy</span>-permitting ocean model are used to calculate the <span class="hlt">eddy</span> statistics needed to inject realistic stochastic noise into a low-resolution, non-<span class="hlt">eddy</span>-permitting version of the same model. A suite of four stochastic experiments is then run to test the sensitivity of the simulated climate to the noise definition by varying the noise amplitude and decorrelation time within reasonable limits. The addition of zero-mean noise to the ocean temperature tendency is found to have a nonzero effect on the mean climate. Specifically, in terms of the ocean temperature and salinity fields both at the surface and at depth, the noise reduces many of the biases in the low-resolution model and causes it to more closely resemble the high-resolution model. The variability of the strength of the global ocean thermohaline circulation is also improved. It is concluded that stochastic ocean perturbations can yield reductions in climate model error that are comparable to those obtained by refining the resolution, but without the increased computational cost. Therefore, stochastic parameterizations of ocean <span class="hlt">eddies</span> have the potential to significantly improve climate simulations. Reference Williams PD, Howe NJ, Gregory JM, Smith RS, and Joshi MM (2016) Improved Climate Simulations through a Stochastic Parameterization of Ocean <span class="hlt">Eddies</span>. Journal of Climate, 29, 8763-8781. http://dx.doi.org/10</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.2290W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.2290W"><span>Improved Climate Simulations through a Stochastic Parameterization of Ocean <span class="hlt">Eddies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Williams, Paul; Howe, Nicola; Gregory, Jonathan; Smith, Robin; Joshi, Manoj</p> <p>2016-04-01</p> <p>In climate simulations, the impacts of the sub-grid scales on the resolved scales are conventionally represented using deterministic closure schemes, which assume that the impacts are uniquely determined by the resolved scales. Stochastic parameterization relaxes this assumption, by sampling the sub-grid variability in a computationally inexpensive manner. This presentation shows that the simulated climatological state of the ocean is improved in many respects by implementing a simple stochastic parameterization of ocean <span class="hlt">eddies</span> into a coupled atmosphere-ocean general circulation model. Simulations from a high-resolution, <span class="hlt">eddy</span>-permitting ocean model are used to calculate the <span class="hlt">eddy</span> statistics needed to inject realistic stochastic noise into a low-resolution, non-<span class="hlt">eddy</span>-permitting version of the same model. A suite of four stochastic experiments is then run to test the sensitivity of the simulated climate to the noise definition, by varying the noise amplitude and decorrelation time within reasonable limits. The addition of zero-mean noise to the ocean temperature tendency is found to have a non-zero effect on the mean climate. Specifically, in terms of the ocean temperature and salinity fields both at the surface and at depth, the noise reduces many of the biases in the low-resolution model and causes it to more closely resemble the high-resolution model. The variability of the strength of the global ocean thermohaline circulation is also improved. It is concluded that stochastic ocean perturbations can yield reductions in climate model error that are comparable to those obtained by refining the resolution, but without the increased computational cost. Therefore, stochastic parameterizations of ocean <span class="hlt">eddies</span> have the potential to significantly improve climate simulations. Reference PD Williams, NJ Howe, JM Gregory, RS Smith, and MM Joshi (2016) Improved Climate Simulations through a Stochastic Parameterization of Ocean <span class="hlt">Eddies</span>. Journal of Climate, under revision.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19531505','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19531505"><span>Large <span class="hlt">eddy</span> simulation applications in gas turbines.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Menzies, Kevin</p> <p>2009-07-28</p> <p>The gas turbine presents significant challenges to any computational fluid dynamics <span class="hlt">techniques</span>. The combination of a wide range of flow phenomena with complex geometry is difficult to model in the context of Reynolds-averaged Navier-Stokes (RANS) solvers. We review the potential for large <span class="hlt">eddy</span> simulation (LES) in modelling the flow in the different components of the gas turbine during a practical engineering design cycle. We show that while LES has demonstrated considerable promise for reliable prediction of many flows in the engine that are difficult for RANS it is not a panacea and considerable application challenges remain. However, for many flows, especially those dominated by shear layer mixing such as in combustion chambers and exhausts, LES has demonstrated a clear superiority over RANS for moderately complex geometries although at significantly higher cost which will remain an issue in making the calculations relevant within the design cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009AIPC.1096..371W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009AIPC.1096..371W"><span><span class="hlt">Eddy</span> Current System for Detection of Cracking Beneath Braiding in Corrugated Metal Hose</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wincheski, Buzz; Simpson, John; Hall, George</p> <p>2009-03-01</p> <p>In this paper an <span class="hlt">eddy</span> current system for the detection of partially-through-the-thickness cracks in corrugated metal hose is presented. Design criteria based upon the geometry and conductivity of the part are developed and applied to the fabrication of a prototype inspection system. Experimental data are used to highlight the capabilities of the system and an image processing <span class="hlt">technique</span> is presented to improve flaw detection capabilities. A case study for detection of cracking damage in a space shuttle radiator retract flex hoses is also presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20090009966','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20090009966"><span><span class="hlt">Eddy</span> Current System for Detection of Cracking Beneath Braiding in Corrugated Metal Hose</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wincheski, Buzz; Simpson, John; Hall, George</p> <p>2008-01-01</p> <p>In this paper an <span class="hlt">eddy</span> current system for the detection of partially-through-the-thickness cracks in corrugated metal hose is presented. Design criteria based upon the geometry and conductivity of the part are developed and applied to the fabrication of a prototype inspection system. Experimental data are used to highlight the capabilities of the system and an image processing <span class="hlt">technique</span> is presented to improve flaw detection capabilities. A case study for detection of cracking damage in a space shuttle radiator retract flex hoses is also presented.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_19");'>19</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li class="active"><span>21</span></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_21 --> <div id="page_22" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="421"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.4444C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.4444C"><span>The formation processes of phytoplankton growth and decline in mesoscale <span class="hlt">eddies</span> in the western North Pacific Ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chang, Yu-Lin; Miyazawa, Yasumasa; Oey, Lie-Yauw; Kodaira, Tsubasa; Huang, Shihming</p> <p>2017-05-01</p> <p>In this study, we investigate the processes of phytoplankton growth and decline in mesoscale <span class="hlt">eddies</span> in the western North Pacific Ocean based on the in situ chlorophyll data obtained from 52 cruises conducted by the Japan Meteorological Agency together with idealized numerical simulations. Both the observation and model results suggest that chlorophyll/phytoplankton concentrations are higher in cold than in warm <span class="hlt">eddies</span> in near-surface water (z > -70 m). In the idealized simulation, the isopycnal movements associated with upwelling/downwelling transport phytoplankton and nutrients to different vertical depths during <span class="hlt">eddy</span> formation (stage A). Phytoplankton and nutrients in cold <span class="hlt">eddies</span> is transported toward shallower waters while those in warm <span class="hlt">eddies</span> move toward deeper waters. In the period after the <span class="hlt">eddy</span> has formed (stage B), sunlight and initially upwelled nutrients together promote the growth of phytoplankton in cold <span class="hlt">eddies</span>. Phytoplankton in warm <span class="hlt">eddies</span> decays due to insufficient sunlight in deeper waters. In stage B, upwelling and downwelling coexist in both warm and cold <span class="hlt">eddies</span>, contributing nearly equally to vertical displacement. The upwelling/downwelling-induced nitrate flux accounts for a small percentage (˜3%) of the total nitrate flux in stage B. The vertical velocity caused by propagating <span class="hlt">eddies</span>, therefore, is not the primary factor causing differences in phytoplankton concentrations between stage-B warm and cold <span class="hlt">eddies</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19880067914&hterms=Good+Reasons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DGood%2BReasons','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19880067914&hterms=Good+Reasons&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3DGood%2BReasons"><span>The <span class="hlt">eddy</span> transport of nonconserved trace species derived from satellite data</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, Anne K.; Lyjak, Lawrence V.; Gille, John C.</p> <p>1988-01-01</p> <p>Using the approach of the Garcia and Solomon (1983) model and data obtained by the LIMS instrument on Nimbus 7, the chemical <span class="hlt">eddy</span> transport matrix for planetary waves was calculated, and the chemical <span class="hlt">eddy</span> contribution to the components of the matrix obtained from the LIMS satellite observations was computed using specified photochemical damping time scales. The dominant component of the transport matrices for several winter months were obtained for ozone, nitric acid, and quasi-geostrophic potential vorticity (PV), and the parameterized transports of these were compared with the 'exact' transports, computed directly from the <span class="hlt">eddy</span> LIMS data. The results indicate that the chemical <span class="hlt">eddy</span> effect can account for most of the observed ozone transport in early winter, decreasing to less than half in late winter. The agreement between the parameterized and observed nitric acid and PV was not as good. Reasons for this are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20150020950','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20150020950"><span>Process Specification for <span class="hlt">Eddy</span> Current Inspection</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Koshti, Ajay</p> <p>2011-01-01</p> <p>This process specification establishes the minimum requirements for <span class="hlt">eddy</span> current inspection of flat surfaces, fastener holes, threaded fasteners and seamless and welded tubular products made from nonmagnetic alloys such as aluminum and stainless steel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5388918','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5388918"><span>An Intrathermocline <span class="hlt">Eddy</span> and a tropical cyclone in the Bay of Bengal</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Gordon, Arnold L.; Shroyer, Emily; Murty, V. S. N.</p> <p>2017-01-01</p> <p>The Bay of Bengal, subjected to monsoonal forcing and tropical cyclones, displays a complex field of ocean <span class="hlt">eddies</span>. On 5 December 2013 a sub-surface vortex or Intrathermocline <span class="hlt">Eddy</span> (ITE) composed of water characteristic of the Andaman Sea was observed within the thermocline of the western Bay of Bengal. We propose that the ITE was the product of Tropical Cyclone Lehar interaction on 27 November 2013 with a westward propagating surface <span class="hlt">eddy</span> from the eastern Bay of Bengal. While Lehar’s interaction with the ocean initially removes heat from the upper layers of the <span class="hlt">eddy</span>, air-sea flux is limited as the deeper portions of the <span class="hlt">eddy</span> was subducted into the stratified thermocline, inhibiting further interaction with the atmosphere. The ITE core from 30 to 150 m is thus isolated from local air-sea fluxes by strong stratification at the mixed layer base, and its periphery is stable to shear instability, suggestive of longevity and the ability to carry water far distances with minimal modification. PMID:28401909</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://pubs.er.usgs.gov/publication/70171384','USGSPUBS'); return false;" href="https://pubs.er.usgs.gov/publication/70171384"><span>Component greenhouse gas fluxes and radiative balance from two deltaic marshes in Louisiana: Pairing chamber <span class="hlt">techniques</span> and <span class="hlt">eddy</span> covariance</span></a></p> <p><a target="_blank" href="http://pubs.er.usgs.gov/pubs/index.jsp?view=adv">USGS Publications Warehouse</a></p> <p>Krauss, Ken W.; Holm, Guerry O.; Perez, Brian C.; McWhorter, David E.; Cormier, Nicole; Moss, Rebecca; Johnson, Darren; Neubauer, Scott C; Raynie, Richard C</p> <p>2016-01-01</p> <p>Coastal marshes take up atmospheric CO2 while emitting CO2, CH4, and N2O. This ability to sequester carbon (C) is much greater for wetlands on a per-area basis than from most ecosystems, facilitating scientific, political, and economic interest in their value as greenhouse gas sinks. However, the greenhouse gas balance of Gulf of Mexico wetlands is particularly understudied. We describe the net ecosystem exchange (NEEc) of CO2 and CH4 using <span class="hlt">eddy</span> covariance (EC) in comparison with fluxes of CO2, CH4, and N2O using chambers from brackish and freshwater marshes in Louisiana, USA. From EC, we found that 182 g C m-2 y-1 was lost through NEEc from the brackish marsh. Of this, 11 g C m-2 y-1 resulted from net CH4 emissions and the remaining 171 g C m-2 y-1 resulted from net CO2 emissions. In contrast, -290 g C m2 y-1 was taken up through NEEc by the freshwater marsh, with 47 g C m-2 y-1 emitted as CH4 and -337 g C m-2 y-1 taken up as CO2. From chambers, we discovered that neither site had large fluxes of N2O. Sustained-flux greenhouse gas accounting metrics indicated that both marshes had a positive (warming) radiative balance, with the brackish marsh having a substantially greater warming effect than the freshwater marsh. That net respiratory emissions of CO2 and CH4 as estimated through chamber <span class="hlt">techniques</span> were 2-4 times different from emissions estimated through EC requires additional understanding of the artifacts created by different spatial and temporal sampling footprints between <span class="hlt">techniques</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1358666-equilibrium-reconstruction-eddy-currents-lithium-tokamak-experiment','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1358666-equilibrium-reconstruction-eddy-currents-lithium-tokamak-experiment"><span>Equilibrium reconstruction with 3D <span class="hlt">eddy</span> currents in the Lithium Tokamak eXperiment</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Hansen, C.; Boyle, D. P.; Schmitt, J. C.; ...</p> <p>2017-04-18</p> <p>Axisymmetric free-boundary equilibrium reconstructions of tokamak plasmas in the Lithium Tokamak eXperiment (LTX) are performed using the PSI-Tri equilibrium code. Reconstructions in LTX are complicated by the presence of long-lived non-axisymmetric <span class="hlt">eddy</span> currents generated by a vacuum vessel and first wall structures. To account for this effect, reconstructions are performed with additional toroidal current sources in these conducting regions. The <span class="hlt">eddy</span> current sources are fixed in their poloidal distributions, but their magnitude is adjusted as part of the full reconstruction. <span class="hlt">Eddy</span> distributions are computed by toroidally averaging currents, generated by coupling to vacuum field coils, from a simplified 3D filamentmore » model of important conducting structures. The full 3D <span class="hlt">eddy</span> current fields are also used to enable the inclusion of local magnetic field measurements, which have strong 3D <span class="hlt">eddy</span> current pick-up, as reconstruction constraints. Using this method, equilibrium reconstruction yields good agreement with all available diagnostic signals. Here, an accompanying field perturbation produced by 3D <span class="hlt">eddy</span> currents on the plasma surface with a primarily n = 2, m = 1 character is also predicted for these equilibria.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GeoRL..45.4390T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GeoRL..45.4390T"><span><span class="hlt">Eddy</span> Covariance Measurements of Methane Flux at a Tropical Peat Forest in Sarawak, Malaysian Borneo</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tang, Angela C. I.; Stoy, Paul C.; Hirata, Ryuichi; Musin, Kevin K.; Aeries, Edward B.; Wenceslaus, Joseph; Melling, Lulie</p> <p>2018-05-01</p> <p>Tropical biogenic sources are a likely cause of the recent increase in global atmospheric methane concentration. To improve our understanding of tropical methane sources, we used the <span class="hlt">eddy</span> covariance <span class="hlt">technique</span> to measure CH4 flux (FCH4) between a tropical peat forest ecosystem and the atmosphere in Malaysian Borneo over a 2-month period during the wet season. Mean daily FCH4 during the measurement period, on the order of 0.024 g C-CH4·m-2·day-1, was similar to <span class="hlt">eddy</span> covariance FCH4 measurements from tropical rice agroecosystems and boreal fen ecosystems. A linear modeling analysis demonstrated that air temperature (Tair) was critical for modeling FCH4 before the water table breached the surface and that water table alone explained some 20% of observed FCH4 variability once standing water emerged. Future research should measure FCH4 on an annual basis from multiple tropical ecosystems to better constrain tropical biogenic methane sources.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19940019681','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19940019681"><span>A large <span class="hlt">eddy</span> simulation scheme for turbulent reacting flows</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gao, Feng</p> <p>1993-01-01</p> <p>The recent development of the dynamic subgrid-scale (SGS) model has provided a consistent method for generating localized turbulent mixing models and has opened up great possibilities for applying the large <span class="hlt">eddy</span> simulation (LES) <span class="hlt">technique</span> to real world problems. Given the fact that the direct numerical simulation (DNS) can not solve for engineering flow problems in the foreseeable future (Reynolds 1989), the LES is certainly an attractive alternative. It seems only natural to bring this new development in SGS modeling to bear on the reacting flows. The major stumbling block for introducing LES to reacting flow problems has been the proper modeling of the reaction source terms. Various models have been proposed, but none of them has a wide range of applicability. For example, some of the models in combustion have been based on the flamelet assumption which is only valid for relatively fast reactions. Some other models have neglected the effects of chemical reactions on the turbulent mixing time scale, which is certainly not valid for fast and non-isothermal reactions. The probability density function (PDF) method can be usefully employed to deal with the modeling of the reaction source terms. In order to fit into the framework of LES, a new PDF, the large <span class="hlt">eddy</span> PDF (LEPDF), is introduced. This PDF provides an accurate representation for the filtered chemical source terms and can be readily calculated in the simulations. The details of this scheme are described.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/17510362','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/17510362"><span>Mesoscale <span class="hlt">eddies</span> drive increased silica export in the subtropical Pacific Ocean.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Benitez-Nelson, Claudia R; Bidigare, Robert R; Dickey, Tommy D; Landry, Michael R; Leonard, Carrie L; Brown, Susan L; Nencioli, Francesco; Rii, Yoshimi M; Maiti, Kanchan; Becker, Jamie W; Bibby, Thomas S; Black, Wil; Cai, Wei-Jun; Carlson, Craig A; Chen, Feizhou; Kuwahara, Victor S; Mahaffey, Claire; McAndrew, Patricia M; Quay, Paul D; Rappé, Michael S; Selph, Karen E; Simmons, Melinda P; Yang, Eun Jin</p> <p>2007-05-18</p> <p>Mesoscale <span class="hlt">eddies</span> may play a critical role in ocean biogeochemistry by increasing nutrient supply, primary production, and efficiency of the biological pump, that is, the ratio of carbon export to primary production in otherwise nutrient-deficient waters. We examined a diatom bloom within a cold-core cyclonic <span class="hlt">eddy</span> off Hawaii. <span class="hlt">Eddy</span> primary production, community biomass, and size composition were markedly enhanced but had little effect on the carbon export ratio. Instead, the system functioned as a selective silica pump. Strong trophic coupling and inefficient organic export may be general characteristics of community perturbation responses in the warm waters of the Pacific Ocean.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016PalOc..31..564V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016PalOc..31..564V"><span>Effects of Drake Passage on a strongly <span class="hlt">eddying</span> global ocean</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Viebahn, Jan P.; von der Heydt, Anna S.; Le Bars, Dewi; Dijkstra, Henk A.</p> <p>2016-05-01</p> <p>The climate impact of ocean gateway openings during the Eocene-Oligocene transition is still under debate. Previous model studies employed grid resolutions at which the impact of mesoscale <span class="hlt">eddies</span> has to be parameterized. We present results of a state-of-the-art <span class="hlt">eddy</span>-resolving global ocean model with a closed Drake Passage and compare with results of the same model at noneddying resolution. An analysis of the pathways of heat by decomposing the meridional heat transport into <span class="hlt">eddy</span>, horizontal, and overturning circulation components indicates that the model behavior on the large scale is qualitatively similar at both resolutions. Closing Drake Passage induces (i) sea surface warming around Antarctica due to equatorward expansion of the subpolar gyres, (ii) the collapse of the overturning circulation related to North Atlantic Deep Water formation leading to surface cooling in the North Atlantic, and (iii) significant equatorward <span class="hlt">eddy</span> heat transport near Antarctica. However, quantitative details significantly depend on the chosen resolution. The warming around Antarctica is substantially larger for the noneddying configuration (˜5.5°C) than for the <span class="hlt">eddying</span> configuration (˜2.5°C). This is a consequence of the subpolar mean flow which partitions differently into gyres and circumpolar current at different resolutions. We conclude that for a deciphering of the different mechanisms active in Eocene-Oligocene climate change detailed analyses of the pathways of heat in the different climate subsystems are crucial in order to clearly identify the physical processes actually at work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/pages/biblio/1243064-mean-state-acceleration-cloud-resolving-models-large-eddy-simulations','SCIGOV-DOEP'); return false;" href="https://www.osti.gov/pages/biblio/1243064-mean-state-acceleration-cloud-resolving-models-large-eddy-simulations"><span>Mean-state acceleration of cloud-resolving models and large <span class="hlt">eddy</span> simulations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGES</a></p> <p>Jones, C. R.; Bretherton, C. S.; Pritchard, M. S.</p> <p>2015-10-29</p> <p>In this study, large <span class="hlt">eddy</span> simulations and cloud-resolving models (CRMs) are routinely used to simulate boundary layer and deep convective cloud processes, aid in the development of moist physical parameterization for global models, study cloud-climate feedbacks and cloud-aerosol interaction, and as the heart of superparameterized climate models. These models are computationally demanding, placing practical constraints on their use in these applications, especially for long, climate-relevant simulations. In many situations, the horizontal-mean atmospheric structure evolves slowly compared to the turnover time of the most energetic turbulent <span class="hlt">eddies</span>. We develop a simple scheme to reduce this time scale separation to accelerate themore » evolution of the mean state. Using this approach we are able to accelerate the model evolution by a factor of 2–16 or more in idealized stratocumulus, shallow and deep cumulus convection without substantial loss of accuracy in simulating mean cloud statistics and their sensitivity to climate change perturbations. As a culminating test, we apply this <span class="hlt">technique</span> to accelerate the embedded CRMs in the Superparameterized Community Atmosphere Model by a factor of 2, thereby showing that the method is robust and stable to realistic perturbations across spatial and temporal scales typical in a GCM.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..1712767C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..1712767C"><span>On the coupled use of sapflow and <span class="hlt">eddy</span> covariance measurements: environmental impacts on the evapotranspiration of an heterogeneous - wild olives based - Sardinian ecosystem.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Curreli, Matteo; Corona, Roberto; Montaldo, Nicola; Oren, Ram</p> <p>2015-04-01</p> <p>Sapflow and <span class="hlt">eddy</span> covariance <span class="hlt">techniques</span> are attractive methods for evapotranspiration (ET) estimates. We demonstrated that in Mediterranean ecosystems, characterized by an heterogeneous spatial distribution of different plant functional types (PFT) such as grass and trees, the combined use of these <span class="hlt">techniques</span> becomes essential for the actual ET estimates. Indeed, during the dry summers these water-limited heterogeneous ecosystems are typically characterized by a simple dual PFT system with strong-resistant woody vegetation and bare soil, since grass died. An <span class="hlt">eddy</span> covariance - micrometeorological tower has been installed over an heterogeneous ecosystem at the Orroli site in Sardinia (Italy) from 2003. The site landscape is a mixture of Mediterranean patchy vegetation types: wild olives, different shrubs and herbaceous species, which died during the summer. Where patchy land cover leads and the surface fluxes from different cover are largely different, ET evaluation may be not robust enough and <span class="hlt">eddy</span> covariance method hypothesis are not anymore preserved. In these conditions the sapflow measurements, performed by thermodissipation probes, provide robust estimates of the transpiration from woody vegetation. Through the coupled use of the sapflow sensor observations, a 2D footprint model of the <span class="hlt">eddy</span> covariance tower and high resolution satellite images for the estimate of the foot print land cover map, the <span class="hlt">eddy</span> covariance measurements can be correctly interpreted, and ET components (bare soil evaporation and woody vegetation transpiration) can be separated. Based on the Granier <span class="hlt">technique</span>, 33 thermo-dissipation probes have been built and 6 power regulators have been assembled to provide a constant current of 3V to the sensors. The sensors have been installed at the Orroli site into 15 wild olives clumps with different characteristics in terms of tree size, exposition to wind and solar radiation and soil depth. The sap flow sensors outputs are analyzed to estimate</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD0775990','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD0775990"><span><span class="hlt">Eddy</span> Viscosity for Variable Density Coflowing Streams,</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p></p> <p><span class="hlt">EDDY</span> CURRENTS, *JET MIXING FLOW, *VISCOSITY, *AIR FLOW, MATHEMATICAL MODELS, INCOMPRESSIBLE FLOW, AXISYMMETRIC FLOW, MATHEMATICAL PREDICTION, THRUST AUGMENTATION , EJECTORS , COMPUTER PROGRAMMING, SECONDARY FLOW, DENSITY, MODIFICATION.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013EGUGA..15.9907D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013EGUGA..15.9907D"><span>The Solomon Sea <span class="hlt">eddy</span> activity from a 1/36° regional model</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Djath, Bughsin; Babonneix, Antoine; Gourdeau, Lionel; Marin, Frédéric; Verron, Jacques</p> <p>2013-04-01</p> <p>In the South West Pacific, the Solomon Sea exhibits the highest levels of <span class="hlt">eddy</span> kinetic energy but relatively little is known about the <span class="hlt">eddy</span> activity in this region. This Sea is directly influenced by a monsoonal regime and ENSO variability, and occupies a strategical location as the Western Boundary Currents exiting it are known to feed the warm pool and to be the principal sources of the Equatorial UnderCurrent. During their transit in the Solomon Sea, meso-scale <span class="hlt">eddies</span> are suspected to notably interact and influence these water masses. The goal of this study is to give an exhaustive description of this <span class="hlt">eddy</span> activity. A dual approach, based both on altimetric data and high resolution modeling, has then been chosen for this purpose. First, an algorithm is applied on nearly 20 years of 1/3° x 1/3° gridded SLA maps (provided by the AVISO project). This allows <span class="hlt">eddies</span> to be automatically detected and tracked, thus providing some basic <span class="hlt">eddy</span> properties. The preliminary results show that two main and distinct types of <span class="hlt">eddies</span> are detected. <span class="hlt">Eddies</span> in the north-eastern part shows a variability associated with the mean structure, while those in the southern part are associated with generation/propagation processes. However, the resolution of the AVISO dataset is not very well suited to observe fine structures and to match with the numerous islands bordering the Solomon Sea. For this reason, we will confront these observations with the outputs of a 1/36° resolution realistic model of the Solomon Sea. The high resolution numerical model (1/36°) indeed permits to reproduce very fine scale features, such as <span class="hlt">eddies</span> and filaments. The model is two-way embedded in a 1/12° regional model which is itself one-way embedded in the DRAKKAR 1/12° global model. The NEMO code is used as well as the AGRIF software for model nestings. Validation is realized by comparison with AVISO observations and available in situ data. In preparing the future wide-swath altimetric SWOT mission that is</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://rosap.ntl.bts.gov/view/dot/10996','DOTNTL'); return false;" href="https://rosap.ntl.bts.gov/view/dot/10996"><span>Test and Evaluation of an <span class="hlt">Eddy</span> Current Clutch/Brake Propulsion System</span></a></p> <p><a target="_blank" href="http://ntlsearch.bts.gov/tris/index.do">DOT National Transportation Integrated Search</a></p> <p></p> <p>1975-01-01</p> <p>This report covers the Phase II effort of a program to develop and test a 15 hp <span class="hlt">eddy</span>-current clutch propulsion system. Included in the Phase 2 effort are the test and evaluation of the <span class="hlt">eddy</span>-current clutch propulsion system on board a test vehicle. Th...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19880019768','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19880019768"><span>Application of optical <span class="hlt">correlation</span> <span class="hlt">techniques</span> to particle imaging velocimetry</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wernet, Mark P.; Edwards, Robert V.</p> <p>1988-01-01</p> <p>Pulsed laser sheet velocimetry yields nonintrusive measurements of velocity vectors across an extended 2-dimensional region of the flow field. The application of optical <span class="hlt">correlation</span> <span class="hlt">techniques</span> to the analysis of multiple exposure laser light sheet photographs can reduce and/or simplify the data reduction time and hardware. Here, Matched Spatial Filters (MSF) are used in a pattern recognition system. Usually MSFs are used to identify the assembly line parts. In this application, the MSFs are used to identify the iso-velocity vector contours in the flow. The patterns to be recognized are the recorded particle images in a pulsed laser light sheet photograph. Measurement of the direction of the partical image displacements between exposures yields the velocity vector. The particle image exposure sequence is designed such that the velocity vector direction is determined unambiguously. A global analysis <span class="hlt">technique</span> is used in comparison to the more common particle tracking algorithms and Young's fringe analysis <span class="hlt">technique</span>.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/10930777','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/10930777"><span>On the use of water phantom images to calibrate and correct <span class="hlt">eddy</span> current induced artefacts in MR diffusion tensor imaging.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Bastin, M E; Armitage, P A</p> <p>2000-07-01</p> <p>The accurate determination of absolute measures of diffusion anisotropy in vivo using single-shot, echo-planar imaging <span class="hlt">techniques</span> requires the acquisition of a set of high signal-to-noise ratio, diffusion-weighted images that are free from <span class="hlt">eddy</span> current induced image distortions. Such geometric distortions can be characterized and corrected in brain imaging data using magnification (M), translation (T), and shear (S) distortion parameters derived from separate water phantom calibration experiments. Here we examine the practicalities of using separate phantom calibration data to correct high b-value diffusion tensor imaging data by investigating the stability of these distortion parameters, and hence the <span class="hlt">eddy</span> currents, with time. It is found that M, T, and S vary only slowly with time (i.e., on the order of weeks), so that calibration scans need not be performed after every patient examination. This not only minimises the scan time required to collect the calibration data, but also the computational time needed to characterize these <span class="hlt">eddy</span> current induced distortions. Examples of how measurements of diffusion anisotropy are improved using this post-processing scheme are also presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/20071120','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/20071120"><span>Double-spin-echo diffusion weighting with a modified <span class="hlt">eddy</span> current adjustment.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Finsterbusch, Jürgen</p> <p>2010-04-01</p> <p>Magnetic field inhomogeneities like <span class="hlt">eddy</span> current-related gradient fields cause geometric distortions in echo-planar imaging (EPI). This in particular affects diffusion-weighted imaging where these distortions vary with the direction of the diffusion weighting and hamper the accurate determination of diffusion parameters. The double-spin-echo preparation often used aims to reduce the cumulative <span class="hlt">eddy</span> current effect by adjusting the diffusion-weighting gradient pulse durations to the time constant of the dominant <span class="hlt">eddy</span> current contribution. However, <span class="hlt">eddy</span> currents with a variety of time constants may be present and cause residual distortions. Here, a modification is proposed where the two bipolar gradient pairs of the preparation are adjusted independently to different time constants. At the expense of a slightly prolonged echo time, residual geometric distortions and correspondingly increased values of the diffusion anisotropy can be reduced as is demonstrated in phantoms and the human brain. Thus, it may help to improve the reliability of diffusion-weighted EPI. Copyright 2010 Elsevier Inc. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1020099','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1020099"><span>Novel <span class="hlt">Techniques</span> for Quantification of <span class="hlt">Correlation</span> Between Primary Liquid Jet Breakup and Downstream Spray Characteristics</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2016-05-08</p> <p>unlimited. 5 1. Introduction Several liquid -fuelled combustion systems, such as liquid propellant rocket engines and gas turbines...AFRL-AFOSR-JP-TR-2016-0084 Novel <span class="hlt">techniques</span> for quantification of <span class="hlt">correlation</span> between primary liquid jet breakup and downstream spray characteristics...to 17 Apr 2016 4.  TITLE AND SUBTITLE Novel <span class="hlt">techniques</span> for quantification of <span class="hlt">correlation</span> between primary liquid jet breakup and downstream spray</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1025503','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1025503"><span>Novel <span class="hlt">Techniques</span> for Quantification of <span class="hlt">Correlation</span> Between Primary Liquid Jet Breakup and Downstream Spray Characteristics</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2016-10-05</p> <p>unlimited. 5 1. Introduction Several liquid -fuelled combustion systems, such as liquid propellant rocket engines and gas turbines...AFRL-AFOSR-JP-TR-2016-0084 Novel <span class="hlt">techniques</span> for quantification of <span class="hlt">correlation</span> between primary liquid jet breakup and downstream spray characteristics...to 17 Apr 2016 4.  TITLE AND SUBTITLE Novel <span class="hlt">techniques</span> for quantification of <span class="hlt">correlation</span> between primary liquid jet breakup and downstream spray</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_20");'>20</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li class="active"><span>22</span></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_22 --> <div id="page_23" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="441"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018Icar..307..150H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018Icar..307..150H"><span>Detection of Northern Hemisphere transient <span class="hlt">eddies</span> at Gale Crater Mars</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Haberle, Robert M.; Juárez, Manuel de la Torre; Kahre, Melinda A.; Kass, David M.; Barnes, Jeffrey R.; Hollingsworth, Jeffery L.; Harri, Ari-Matti; Kahanpää, Henrik</p> <p>2018-06-01</p> <p>The Rover Environmental Monitoring Station (REMS) on the Curiosity Rover is operating in the Southern Hemisphere of Mars and is detecting synoptic period oscillations in the pressure data that we attribute to Northern Hemisphere transient <span class="hlt">eddies</span>. We base this interpretation on the similarity in the periods of the <span class="hlt">eddies</span> and their seasonal variations with those observed in northern midlatitudes by Viking Lander 2 (VL-2) 18 Mars years earlier. Further support for this interpretation comes from global circulation modeling which shows similar behavior in the transient <span class="hlt">eddies</span> at the grid points closest to Curiosity and VL-2. These observations provide the first in situ evidence that the frontal systems often associated with "Flushing Dust Storms" do cross the equator and extend into the Southern Hemisphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFM.V43F..04P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFM.V43F..04P"><span><span class="hlt">Eddy</span> Flow during Magma Emplacement: The Basemelt Sill, Antarctica</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petford, N.; Mirhadizadeh, S.</p> <p>2014-12-01</p> <p>The McMurdo Dry Valleys magmatic system, Antarctica, forms part of the Ferrar dolerite Large Igneous Province. Comprising a vertical stack of interconnected sills, the complex provides a world-class example of pervasive lateral magma flow on a continental scale. The lowermost intrusion (Basement Sill) offers detailed sections through the now frozen particle macrostructure of a congested magma slurry1. Image-based numerical modelling where the intrusion geometry defines its own unique finite element mesh allows simulations of the flow regime to be made that incorporate realistic magma particle size and flow geometries obtained directly from field measurements. One testable outcome relates to the origin of rhythmic layering where analytical results imply the sheared suspension intersects the phase space for particle Reynolds and Peclet number flow characteristic of macroscopic structures formation2. Another relates to potentially novel crystal-liquid segregation due to the formation of <span class="hlt">eddies</span> locally at undulating contacts at the floor and roof of the intrusion. The <span class="hlt">eddies</span> are transient and mechanical in origin, unrelated to well-known fluid dynamical effects around obstacles where flow is turbulent. Numerical particle tracing reveals that these low Re number <span class="hlt">eddies</span> can both trap (remove) and eject particles back into the magma at a later time according to their mass density. This trapping mechanism has potential to develop local variations in structure (layering) and magma chemistry that may otherwise not occur where the contact between magma and country rock is linear. Simulations indicate that <span class="hlt">eddy</span> formation is best developed where magma viscosity is in the range 1-102 Pa s. Higher viscosities (> 103 Pa s) tend to dampen the effect implying <span class="hlt">eddy</span> development is most likely a transient feature. However, it is nice to think that something as simple as a bumpy contact could impart physical and by implication chemical diversity in igneous rocks. 1Marsh, D.B. (2004), A</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19910015372','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19910015372"><span>The impact of greenhouse climate change on the energetics and hydrologic processes of mid-latitude transient <span class="hlt">eddies</span></span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Branscome, Lee E.; Gutowski, William J., Jr.</p> <p>1991-01-01</p> <p>Atmospheric transient <span class="hlt">eddies</span> contribute significantly to mid-latitude energy and water vapor transports. Changes in the global climate, as induced by greenhouse enhancement, will likely alter transient <span class="hlt">eddy</span> behavior. Unraveling all the feedbacks that occur in general circulation models (GCMs) can be difficult. The transient <span class="hlt">eddies</span> are isolated from the feedbacks and are focused on the response of the <span class="hlt">eddies</span> to zonal-mean climate changes that result from CO2-doubling. Using a primitive-equation spectral model, the impact of climate change on the life cycles of transient <span class="hlt">eddies</span> is examined. Transient <span class="hlt">eddy</span> behavior in experiments is compared with initial conditions that are given by the zonal-mean climates of the GCMs with current and doubled amounts of CO2. The smaller meridional temperature gradient in a doubled CO2 climate leads to a reduction in <span class="hlt">eddy</span> kinetic energy, especially in the subtropics. The decrease in subtropical <span class="hlt">eddy</span> energy is related to a substantial reduction in equatorward flux of <span class="hlt">eddy</span> activity during the latter part of the life cycle. The reduction in equatorward energy flux alters the moisture cycle. <span class="hlt">Eddy</span> meridional transport of water vapor is shifted slightly poleward and subtropical precipitation is reduced. The water vapor transport exhibits a relatively small change in magnitude, compared to changes in <span class="hlt">eddy</span> energy, due to the compensating effect of higher specific humidity in the doubled-CO2 climate. An increase in high-latitude precipitation is related to the poleward shift in <span class="hlt">eddy</span> water vapor flux. Surface evaporation amplifies climatic changes in water vapor transport and precipitation in the experiments.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015APS..DFDG30007R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015APS..DFDG30007R"><span>Anisotropic shear dispersion parameterization for ocean <span class="hlt">eddy</span> transport</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Reckinger, Scott; Fox-Kemper, Baylor</p> <p>2015-11-01</p> <p>The effects of mesoscale <span class="hlt">eddies</span> are universally treated isotropically in global ocean general circulation models. However, observations and simulations demonstrate that the mesoscale processes that the parameterization is intended to represent, such as shear dispersion, are typified by strong anisotropy. We extend the Gent-McWilliams/Redi mesoscale <span class="hlt">eddy</span> parameterization to include anisotropy and test the effects of varying levels of anisotropy in 1-degree Community Earth System Model (CESM) simulations. Anisotropy has many effects on the simulated climate, including a reduction of temperature and salinity biases, a deepening of the southern ocean mixed-layer depth, impacts on the meridional overturning circulation and ocean energy and tracer uptake, and improved ventilation of biogeochemical tracers, particularly in oxygen minimum zones. A process-based parameterization to approximate the effects of unresolved shear dispersion is also used to set the strength and direction of anisotropy. The shear dispersion parameterization is similar to drifter observations in spatial distribution of diffusivity and high-resolution model diagnosis in the distribution of <span class="hlt">eddy</span> flux orientation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040120876','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040120876"><span>Application of Self Nulling <span class="hlt">Eddy</span> Current Probe <span class="hlt">Technique</span> to the Detection of Fatigue Crack Initiation and Control of Test Procedures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Namkung, M.; Nath, S.; Wincheski, B.; Fulton, J. P.</p> <p>1994-01-01</p> <p>A major part of fracture mechanics is concerned with studying the initiation and propagation of fatigue cracks. This typically requires constant monitoring of crack growth during fatigue cycles and the knowledge of the precise location of the crack tip at any given time. One <span class="hlt">technique</span> currently available for measuring fatigue crack length is the Potential Drop method. The method, however, may be inaccurate if the direction of crack growth deviates considerably from what was assumed initially or the curvature of the crack becomes significant. Another popular approach is to optically view the crack using a high magnification microscope, but this entails a person constantly monitoring it. The present proposed <span class="hlt">technique</span> uses an automated scheme, in order to eliminate the need for a person to constantly monitor the experiment. Another <span class="hlt">technique</span> under development elsewhere is to digitize an optical image of the test specimen surface and then apply a pattern recognition algorithm to locate the crack tip. A previous publication showed that the self nulling <span class="hlt">eddy</span> current probe successfully tracked a simulated crack in an aluminum sample. This was the impetus to develop an online real time crack monitoring system. An automated system has been developed which includes a two axis scanner mounted on the tensile testing machine, the probe and its instrumentation and a personal computer (PC) to communicate and control all the parameters. The system software controls the testing parameters as well as monitoring the fatigue crack as it propagates. This paper will discuss the experimental setup in detail and demonstrate its capabilities. A three dimensional finite element model is utilized to model the magnetic field distribution due to the probe and how the probe voltage changes as it scans the crack. Experimental data of the probe for different samples under zero load, static load and high cycle fatigue load will be discussed. The final section summarizes the major accomplishments</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.dtic.mil/docs/citations/AD1031984','DTIC-ST'); return false;" href="http://www.dtic.mil/docs/citations/AD1031984"><span>Effects of Angular Variation on Split D Differential <span class="hlt">Eddy</span> Current Probe Response (Postprint)</span></a></p> <p><a target="_blank" href="http://www.dtic.mil/">DTIC Science & Technology</a></p> <p></p> <p>2016-02-10</p> <p>AFRL-RX-WP-JA-2016-0327 EFFECTS OF ANGULAR VARIATION ON SPLIT D DIFFERENTIAL <span class="hlt">EDDY</span> CURRENT PROBE RESPONSE (POSTPRINT) Ryan D...March 2014 – 22 September 2015 4. TITLE AND SUBTITLE EFFECTS OF ANGULAR VARIATION ON SPLIT D DIFFERENTIAL <span class="hlt">EDDY</span> CURRENT PROBE RESPONSE (POSTPRINT...last few years have seen increased levels of complexity added to push the state-of-the-art modeling software used in <span class="hlt">eddy</span> current NDE today. The added</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGD....1218253F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGD....1218253F"><span>Bathypelagic particle flux signatures from a suboxic <span class="hlt">eddy</span> in the oligotrophic tropical North Atlantic: production, sedimentation and preservation</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fischer, G.; Karstensen, J.; Romero, O.; Baumann, K.-H.; Donner, B.; Hefter, J.; Mollenhauer, G.; Iversen, M.; Fiedler, B.; Monteiro, I.; Körtzinger, A.</p> <p>2015-11-01</p> <p>Particle fluxes at the Cape Verde Ocean Observatory (CVOO) in the eastern tropical North Atlantic for the period December 2009 until May 2011 are discussed based on bathypelagic sediment trap time series data collected at 1290 and 3439 m water depth. The typically oligotrophic particle flux pattern with weak seasonality is modified by the appearance of a highly productive and low oxygen anticyclonic modewater <span class="hlt">eddy</span> (ACME) in winter 2010. The <span class="hlt">eddy</span> passage was accompanied by unusually high mass fluxes, lasting from December 2009 to May 2010. Distinct biogenic silica (BSi) and organic carbon flux peaks were observed in February-March 2010 when the <span class="hlt">eddy</span> approached CVOO. The flux of the lithogenic component, mostly mineral dust, was well <span class="hlt">correlated</span> to that of organic carbon in particular in the deep trap samples, suggesting a close coupling. The lithogenic ballasting obviously resulted in high particle settling rates and, thus, a fast transfer of epi-/mesopelagic signatures to the bathypelagic traps. Molar C : N ratios of organic matter during the ACME passage were around 18 and 25 for the upper and lower trap samples, respectively. This suggests that some production under nutrient (nitrate) limitation in the upper few tens of meters above the zone of suboxia might have occurred in the beginning of 2010. The δ15N record showed a decrease from January to March 2010 while the organic carbon and N fluxes increased. The causes of enhanced sedimentation from the <span class="hlt">eddy</span> in February/March 2010 remain elusive but nutrient depletion and/or a high availability of dust as ballast mineral for organic-rich aggregates might have contributed to the elevated fluxes during the <span class="hlt">eddy</span> passage. Remineralization of sinking organic-rich particles could have contributed to the formation of a suboxic zone at shallow depth. Although the <span class="hlt">eddy</span> has been formed in the African coastal area in summer 2009, no indication of coastal flux signatures were found in the sediment traps, suggesting an</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017BGeo...14.2167K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017BGeo...14.2167K"><span>Upwelling and isolation in oxygen-depleted anticyclonic modewater <span class="hlt">eddies</span> and implications for nitrate cycling</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Karstensen, Johannes; Schütte, Florian; Pietri, Alice; Krahmann, Gerd; Fiedler, Björn; Grundle, Damian; Hauss, Helena; Körtzinger, Arne; Löscher, Carolin R.; Testor, Pierre; Vieira, Nuno; Visbeck, Martin</p> <p>2017-04-01</p> <p>The temporal evolution of the physical and biogeochemical structure of an oxygen-depleted anticyclonic modewater <span class="hlt">eddy</span> is investigated over a 2-month period using high-resolution glider and ship data. A weakly stratified <span class="hlt">eddy</span> core (squared buoyancy frequency N2 ˜ 0.1 × 10-4 s-2) at shallow depth is identified with a horizontal extent of about 70 km and bounded by maxima in N2. The upper N2 maximum (3-5 × 10-4 s-2) coincides with the mixed layer base and the lower N2 maximum (0.4 × 10-4 s-2) is found at about 200 m depth in the <span class="hlt">eddy</span> centre. The <span class="hlt">eddy</span> core shows a constant slope in temperature/salinity (T/S) characteristic over the 2 months, but an erosion of the core progressively narrows down the T/S range. The <span class="hlt">eddy</span> minimal oxygen concentrations decreased by about 5 µmol kg-1 in 2 months, confirming earlier estimates of oxygen consumption rates in these <span class="hlt">eddies</span>. Separating the mesoscale and perturbation flow components reveals oscillating velocity finestructure ( ˜ 0.1 m s-1) underneath the <span class="hlt">eddy</span> and at its flanks. The velocity finestructure is organized in layers that align with layers in properties (salinity, temperature) but mostly cross through surfaces of constant density. The largest magnitude in velocity finestructure is seen between the surface and 140 m just outside the maximum mesoscale flow but also in a layer underneath the <span class="hlt">eddy</span> centre, between 250 and 450 m. For both regions a cyclonic rotation of the velocity finestructure with depth suggests the vertical propagation of near-inertial wave (NIW) energy. Modification of the planetary vorticity by anticyclonic (<span class="hlt">eddy</span> core) and cyclonic (<span class="hlt">eddy</span> periphery) relative vorticity is most likely impacting the NIW energy propagation. Below the low oxygen core salt-finger type double diffusive layers are found that align with the velocity finestructure. Apparent oxygen utilization (AOU) versus dissolved inorganic nitrate (NO3-) ratios are about twice as high (16) in the <span class="hlt">eddy</span> core compared to surrounding waters (8</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2005OcMod...8....1C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2005OcMod...8....1C"><span>Modeling mesoscale <span class="hlt">eddies</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Canuto, V. M.; Dubovikov, M. S.</p> <p></p> <p>Mesoscale <span class="hlt">eddies</span> are not resolved in coarse resolution ocean models and must be modeled. They affect both mean momentum and scalars. At present, no generally accepted model exists for the former; in the latter case, mesoscales are modeled with a bolus velocity u∗ to represent a sink of mean potential energy. However, comparison of u∗(model) vs. u∗ (<span class="hlt">eddy</span> resolving code, [J. Phys. Ocean. 29 (1999) 2442]) has shown that u∗(model) is incomplete and that additional terms, "unrelated to thickness source or sinks", are required. Thus far, no form of the additional terms has been suggested. To describe mesoscale <span class="hlt">eddies</span>, we employ the Navier-Stokes and scalar equations and a turbulence model to treat the non-linear interactions. We then show that the problem reduces to an eigenvalue problem for the mesoscale Bernoulli potential. The solution, which we derive in analytic form, is used to construct the momentum and thickness fluxes. In the latter case, the bolus velocity u∗ is found to contain two types of terms: the first type entails the gradient of the mean potential vorticity and represents a positive contribution to the production of mesoscale potential energy; the second type of terms, which is new, entails the velocity of the mean flow and represents a negative contribution to the production of mesoscale potential energy, or equivalently, a backscatter process whereby a fraction of the mesoscale potential energy is returned to the original reservoir of mean potential energy. This type of terms satisfies the physical description of the additional terms given by [J. Phys. Ocean. 29 (1999) 2442]. The mesoscale flux that enters the momentum equations is also contributed by two types of terms of the same physical nature as those entering the thickness flux. The potential vorticity flux is also shown to contain two types of terms: the first is of the gradient-type while the other terms entail the velocity of the mean flow. An expression is derived for the mesoscale</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26635077','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26635077"><span>Distant Influence of Kuroshio <span class="hlt">Eddies</span> on North Pacific Weather Patterns?</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ma, Xiaohui; Chang, Ping; Saravanan, R; Montuoro, Raffaele; Hsieh, Jen-Shan; Wu, Dexing; Lin, Xiaopei; Wu, Lixin; Jing, Zhao</p> <p>2015-12-04</p> <p>High-resolution satellite measurements of surface winds and sea-surface temperature (SST) reveal strong coupling between meso-scale ocean <span class="hlt">eddies</span> and near-surface atmospheric flow over <span class="hlt">eddy</span>-rich oceanic regions, such as the Kuroshio and Gulf Stream, highlighting the importance of meso-scale oceanic features in forcing the atmospheric planetary boundary layer (PBL). Here, we present high-resolution regional climate modeling results, supported by observational analyses, demonstrating that meso-scale SST variability, largely confined in the Kuroshio-Oyashio confluence region (KOCR), can further exert a significant distant influence on winter rainfall variability along the U.S. Northern Pacific coast. The presence of meso-scale SST anomalies enhances the diabatic conversion of latent heat energy to transient <span class="hlt">eddy</span> energy, intensifying winter cyclogenesis via moist baroclinic instability, which in turn leads to an equivalent barotropic downstream anticyclone anomaly with reduced rainfall. The finding points to the potential of improving forecasts of extratropical winter cyclones and storm systems and projections of their response to future climate change, which are known to have major social and economic impacts, by improving the representation of ocean <span class="hlt">eddy</span>-atmosphere interaction in forecast and climate models.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/880240','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/880240"><span>Contoured Surface <span class="hlt">Eddy</span> Current Inspection System</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Batzinger, Thomas James; Fulton, James Paul; Rose, Curtis Wayne; Perocchi, Lee Cranford</p> <p>2003-04-08</p> <p><span class="hlt">Eddy</span> current inspection of a contoured surface of a workpiece is performed by forming a backing piece of flexible, resiliently yieldable material with a contoured exterior surface conforming in shape to the workpiece contoured surface. The backing piece is preferably cast in place so as to conform to the workpiece contoured surface. A flexible <span class="hlt">eddy</span> current array probe is attached to the contoured exterior surface of the backing piece such that the probe faces the contoured surface of the workpiece to be inspected when the backing piece is disposed adjacent to the workpiece. The backing piece is then expanded volumetrically by inserting at least one shim into a slot in the backing piece to provide sufficient contact pressure between the probe and the workpiece contoured surface to enable the inspection of the workpiece contoured surface to be performed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1122319-tidal-residual-eddies-effect-water-exchange-puget-sound','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1122319-tidal-residual-eddies-effect-water-exchange-puget-sound"><span>Tidal Residual <span class="hlt">Eddies</span> and their Effect on Water Exchange in Puget Sound</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Yang, Zhaoqing; Wang, Taiping</p> <p></p> <p>Tidal residual <span class="hlt">eddies</span> are one of the important hydrodynamic features in tidally dominant estuaries and coastal bays, and they could have significant effects on water exchange in a tidal system. This paper presents a modeling study of tides and tidal residual <span class="hlt">eddies</span> in Puget Sound, a tidally dominant fjord-like estuary in the Pacific Northwest coast, using a three-dimensional finite-volume coastal ocean model. Mechanisms of vorticity generation and asymmetric distribution patterns around an island/headland were analyzed using the dynamic vorticity transfer approach and numerical experiments. Model results of Puget Sound show that a number of large twin tidal residual <span class="hlt">eddies</span> existmore » in the Admiralty Inlet because of the presence of major headlands in the inlet. Simulated residual vorticities near the major headlands indicate that the clockwise tidal residual <span class="hlt">eddy</span> (negative vorticity) is generally stronger than the anticlockwise <span class="hlt">eddy</span> (positive vorticity) because of the effect of Coriolis force. The effect of tidal residual <span class="hlt">eddies</span> on water exchange in Puget Sound and its sub-basins were evaluated by simulations of dye transport. It was found that the strong transverse variability of residual currents in the Admiralty Inlet results in a dominant seaward transport along the eastern shore and a dominant landward transport along the western shore of the Inlet. A similar transport pattern in Hood Canal is caused by the presence of tidal residual <span class="hlt">eddies</span> near the entrance of the canal. Model results show that tidal residual currents in Whidbey Basin are small in comparison to other sub-basins. A large clockwise residual circulation is formed around Vashon Island near entrance of South Sound, which can potentially constrain the water exchange between the Central Basin and South Sound.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/22918621','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/22918621"><span><span class="hlt">Eddy</span> current compensation for delta relaxation enhanced MR by dynamic reference phase modulation.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Hoelscher, Uvo Christoph; Jakob, Peter M</p> <p>2013-04-01</p> <p><span class="hlt">Eddy</span> current compensation by dynamic reference phase modulation (eDREAM) is a compensation method for <span class="hlt">eddy</span> current fields induced by B 0 field-cycling which occur in delta relaxation enhanced MR (dreMR) imaging. The presented method is based on a dynamic frequency adjustment and prevents <span class="hlt">eddy</span> current related artifacts. It is easy to implement and can be completely realized in software for any imaging sequence. In this paper, the theory of eDREAM is derived and two applications are demonstrated. The theory describes how to model the behavior of the <span class="hlt">eddy</span> currents and how to implement the compensation. Phantom and in vivo measurements are carried out and demonstrate the benefits of eDREAM. A comparison of images acquired with and without eDREAM shows a significant improvement in dreMR image quality. Images without eDREAM suffer from severe artifacts and do not allow proper interpretation while images with eDREAM are artifact free. In vivo experiments demonstrate that dreMR imaging without eDREAM is not feasible as artifacts completely change the image contrast. eDREAM is a flexible <span class="hlt">eddy</span> current compensation for dreMR. It is capable of completely removing the influence of <span class="hlt">eddy</span> currents such that the dreMR images do not suffer from artifacts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/22482816-measurement-toroidal-vessel-eddy-current-during-plasma-disruption-text','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/22482816-measurement-toroidal-vessel-eddy-current-during-plasma-disruption-text"><span>Measurement of toroidal vessel <span class="hlt">eddy</span> current during plasma disruption on J-TEXT</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Liu, L. J.; Yu, K. X.; Zhang, M., E-mail: zhangming@hust.edu.cn</p> <p>2016-01-15</p> <p>In this paper, we have employed a thin, printed circuit board <span class="hlt">eddy</span> current array in order to determine the radial distribution of the azimuthal component of the <span class="hlt">eddy</span> current density at the surface of a steel plate. The <span class="hlt">eddy</span> current in the steel plate can be calculated by analytical methods under the simplifying assumptions that the steel plate is infinitely large and the exciting current is of uniform distribution. The measurement on the steel plate shows that this method has high spatial resolution. Then, we extended this methodology to a toroidal geometry with the objective of determining the poloidal distributionmore » of the toroidal component of the <span class="hlt">eddy</span> current density associated with plasma disruption in a fusion reactor called J-TEXT. The preliminary measured result is consistent with the analysis and calculation results on the J-TEXT vacuum vessel.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26827315','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26827315"><span>Measurement of toroidal vessel <span class="hlt">eddy</span> current during plasma disruption on J-TEXT.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Liu, L J; Yu, K X; Zhang, M; Zhuang, G; Li, X; Yuan, T; Rao, B; Zhao, Q</p> <p>2016-01-01</p> <p>In this paper, we have employed a thin, printed circuit board <span class="hlt">eddy</span> current array in order to determine the radial distribution of the azimuthal component of the <span class="hlt">eddy</span> current density at the surface of a steel plate. The <span class="hlt">eddy</span> current in the steel plate can be calculated by analytical methods under the simplifying assumptions that the steel plate is infinitely large and the exciting current is of uniform distribution. The measurement on the steel plate shows that this method has high spatial resolution. Then, we extended this methodology to a toroidal geometry with the objective of determining the poloidal distribution of the toroidal component of the <span class="hlt">eddy</span> current density associated with plasma disruption in a fusion reactor called J-TEXT. The preliminary measured result is consistent with the analysis and calculation results on the J-TEXT vacuum vessel.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AdWR...50...62A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AdWR...50...62A"><span>On the discrepancy between <span class="hlt">eddy</span> covariance and lysimetry-based surface flux measurements under strongly advective conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alfieri, Joseph G.; Kustas, William P.; Prueger, John H.; Hipps, Lawrence E.; Evett, Steven R.; Basara, Jeffrey B.; Neale, Christopher M. U.; French, Andrew N.; Colaizzi, Paul; Agam, Nurit; Cosh, Michael H.; Chavez, José L.; Howell, Terry A.</p> <p>2012-12-01</p> <p>Discrepancies can arise among surface flux measurements collected using disparate <span class="hlt">techniques</span> due to differences in both the instrumentation and theoretical underpinnings of the different measurement methods. Using data collected primarily within a pair of irrigated cotton fields as a part of the 2008 Bushland Evapotranspiration and Remote Sensing Experiment (BEAREX08), flux measurements collected with two commonly-used methods, <span class="hlt">eddy</span> covariance (EC) and lysimetry (LY), were compared and substantial differences were found. Daytime mean differences in the flux measurements from the two <span class="hlt">techniques</span> could be in excess of 200 W m-2 under strongly advective conditions. Three causes for this disparity were found: (i) the failure of the <span class="hlt">eddy</span> covariance systems to fully balance the surface energy budget, (ii) flux divergence due to the local advection of warm, dry air over the irrigated cotton fields, and (iii) the failure of lysimeters to accurately represent the surface properties of the cotton fields as a whole. Regardless of the underlying cause, the discrepancy among the flux measurements underscores the difficulty in collecting these measurements under strongly advective conditions. It also raises awareness of the uncertainty associated with in situ micrometeorological measurements and the need for caution when using such data for model validation or as observational evidence to definitively support or refute scientific hypotheses.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1362279','SCIGOV-DOEDE'); return false;" href="https://www.osti.gov/servlets/purl/1362279"><span>Flux Tower <span class="hlt">Eddy</span> Covariance and Meteorological Measurements for Barrow, Alaska: 2012-2016</span></a></p> <p><a target="_blank" href="http://www.osti.gov/dataexplorer">DOE Data Explorer</a></p> <p>Dengel, Sigrid; Torn, Margaret; Billesbach, David</p> <p>2017-08-24</p> <p>The dataset contains half-hourly <span class="hlt">eddy</span> covariance flux measurements and determinations, companion meteorological measurements, and ancillary data from the flux tower (US-NGB) on the Barrow Environmental Observatory at Barrow (Utqiagvik), Alaska for the period 2012 through 2016. Data have been processed using <span class="hlt">Eddy</span>Pro software and screened by the contributor. The flux tower sits in an Arctic coastal tundra ecosystem. This dataset updates a previous dataset by reprocessing a longer period of record in the same manner. Related dataset "<span class="hlt">Eddy</span>-Covariance and auxiliary measurements, NGEE-Barrow, 2012-2013" DOI:10.5440/1124200.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4922168','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4922168"><span>Encounter with mesoscale <span class="hlt">eddies</span> enhances survival to settlement in larval coral reef fishes</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shulzitski, Kathryn; Sponaugle, Su; Hauff, Martha; Walter, Kristen D.; Cowen, Robert K.</p> <p>2016-01-01</p> <p>Oceanographic features, such as <span class="hlt">eddies</span> and fronts, enhance and concentrate productivity, generating high-quality patches that dispersive marine larvae may encounter in the plankton. Although broad-scale movement of larvae associated with these features can be captured in biophysical models, direct evidence of processes influencing survival within them, and subsequent effects on population replenishment, are unknown. We sequentially sampled cohorts of coral reef fishes in the plankton and nearshore juvenile habitats in the Straits of Florida and used otolith microstructure analysis to compare growth and size-at-age of larvae collected inside and outside of mesoscale <span class="hlt">eddies</span> to those that survived to settlement. Larval habitat altered patterns of growth and selective mortality: Thalassoma bifasciatum and Cryptotomus roseus that encountered <span class="hlt">eddies</span> in the plankton grew faster than larvae outside of <span class="hlt">eddies</span> and likely experienced higher survival to settlement. During warm periods, T. bifasciatum residing outside of <span class="hlt">eddies</span> in the oligotrophic Florida Current experienced high mortality and only the slowest growers survived early larval life. Such slow growth is advantageous in nutrient poor habitats when warm temperatures increase metabolic demands but is insufficient for survival beyond the larval stage because only fast-growing larvae successfully settled to reefs. Because larvae arriving to the Straits of Florida from distant sources must spend long periods of time outside of <span class="hlt">eddies</span>, our results indicate that they have a survival disadvantage. High productivity features such as <span class="hlt">eddies</span> not only enhance the survival of pelagic larvae, but also potentially increase the contribution of locally spawned larvae to reef populations. PMID:27274058</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27553908','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27553908"><span>Key factors of <span class="hlt">eddy</span> current separation for recovering aluminum from crushed e-waste.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ruan, Jujun; Dong, Lipeng; Zheng, Jie; Zhang, Tao; Huang, Mingzhi; Xu, Zhenming</p> <p>2017-02-01</p> <p>Recovery of e-waste in China had caused serious pollutions. <span class="hlt">Eddy</span> current separation is an environment-friendly technology of separating nonferrous metallic particles from crushed e-waste. However, due to complex particle characters, separation efficiency of traditional <span class="hlt">eddy</span> current separator was low. In production, controllable operation factors of <span class="hlt">eddy</span> current separation are feeding speed, (ωR-v), and S p . There is little special information about influencing mechanism and critical parameters of these factors in <span class="hlt">eddy</span> current separation. This paper provided the special information of these key factors in <span class="hlt">eddy</span> current separation of recovering aluminum particles from crushed waste refrigerator cabinets. Detachment angles increased as the increase of (ωR-v). Separation efficiency increased with the growing of detachment angles. Aluminum particles were completely separated from plastic particles in critical parameters of feeding speed 0.5m/s and detachment angles greater than 6.61deg. S p /S m of aluminum particles in crushed waste refrigerators ranged from 0.08 to 0.51. Separation efficiency increased as the increase of S p /S m . This enlightened us to develop new separator to separate smaller nonferrous metallic particles in e-waste recovery. High feeding speed destroyed separation efficiency. However, greater S p of aluminum particles brought positive impact on separation efficiency. Greater S p could increase critical feeding speed to offer greater throughput of <span class="hlt">eddy</span> current separation. This paper will guide <span class="hlt">eddy</span> current separation in production of recovering nonferrous metals from crushed e-waste. Copyright © 2016 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.8068L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.8068L"><span>Hidden biosphere in an oxygen-deficient Atlantic open ocean <span class="hlt">eddy</span>: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Loescher, Carolin; Fischer, Martin; Neulinger, Sven; Fiedler, Björn; Philippi, Miriam; Schütte, Florian; Singh, Arvind; Hauss, Helena; Karstensen, Johannes; Körtzinger, Arne; Schmitz, Ruth</p> <p>2016-04-01</p> <p>The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open ocean oxygen (O2) concentrations of approximately 40 μmol kg-1. The recent discovery of re-occurring mesoscale <span class="hlt">eddies</span> with close to anoxic O2 concentrations (<1 μmol kg-1) located just below the mixed layer has challenged our understanding of O2 distribution and biogeochemical processes in this area. Here, we present the first microbial community study from a deoxygenated anticyclonic modewater <span class="hlt">eddy</span> in the open waters of the ETNA. In the <span class="hlt">eddy</span>, we observed significantly lower bacterial diversity compared to surrounding waters, along with a significant community shift. We detected enhanced primary productivity in the surface layer of the <span class="hlt">eddy</span> indicated by elevated chlorophyll concentrations and carbon uptake rates of up to three times as high as in surrounding waters. Carbon uptake rates below the euphotic zone <span class="hlt">correlated</span> to the presence of a specific high-light ecotype of Prochlorococcus, which is usually underrepresented in the ETNA. Our data indicate that high primary production in the <span class="hlt">eddy</span> fuels export production and supports enhanced respiration in a specific microbial community at shallow depths, below the mixed layer base. The O2-depleted core waters <span class="hlt">eddy</span> promoted transcription of the key gene for denitrification, nirS. This process is usually absent from the open ETNA waters. In light of future projected ocean deoxygenation, our results show that even distinct events of anoxia have the potential to alter microbial community structure with critical impacts on primary productivity and biogeochemical processes of oceanic water bodies.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li class="active"><span>23</span></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_23 --> <div id="page_24" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="461"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGeo...12.7467L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGeo...12.7467L"><span>Hidden biosphere in an oxygen-deficient Atlantic open-ocean <span class="hlt">eddy</span>: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Löscher, C. R.; Fischer, M. A.; Neulinger, S. C.; Fiedler, B.; Philippi, M.; Schütte, F.; Singh, A.; Hauss, H.; Karstensen, J.; Körtzinger, A.; Künzel, S.; Schmitz, R. A.</p> <p>2015-12-01</p> <p>The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open-ocean oxygen (O2) concentrations of approximately 40 μmol kg-1. The recent discovery of re-occurring mesoscale <span class="hlt">eddies</span> with close to anoxic O2 concentrations (< 1 μmol kg-1) located just below the mixed layer has challenged our understanding of O2 distribution and biogeochemical processes in this area. Here, we present the first microbial community study from a deoxygenated anticyclonic modewater <span class="hlt">eddy</span> in the open waters of the ETNA. In the <span class="hlt">eddy</span>, we observed significantly lower bacterial diversity compared to surrounding waters, along with a significant community shift. We detected enhanced primary productivity in the surface layer of the <span class="hlt">eddy</span> indicated by elevated chlorophyll concentrations and carbon uptake rates of up to three times as high as in surrounding waters. Carbon uptake rates below the euphotic zone <span class="hlt">correlated</span> to the presence of a specific high-light ecotype of Prochlorococcus, which is usually underrepresented in the ETNA. Our data indicate that high primary production in the <span class="hlt">eddy</span> fuels export production and supports enhanced respiration in a specific microbial community at shallow depths, below the mixed-layer base. The transcription of the key functional marker gene for dentrification, nirS, further indicated a potential for nitrogen loss processes in O2-depleted core waters of the <span class="hlt">eddy</span>. Dentrification is usually absent from the open ETNA waters. In light of future projected ocean deoxygenation, our results show that even distinct events of anoxia have the potential to alter microbial community structure with critical impacts on primary productivity and biogeochemical processes of oceanic water bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27364521','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27364521"><span>Feasibility of conductivity imaging using subject <span class="hlt">eddy</span> currents induced by switching of MRI gradients.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Oran, Omer Faruk; Ider, Yusuf Ziya</p> <p>2017-05-01</p> <p>To investigate the feasibility of low-frequency conductivity imaging based on measuring the magnetic field due to subject <span class="hlt">eddy</span> currents induced by switching of MRI z-gradients. We developed a simulation model for calculating subject <span class="hlt">eddy</span> currents and the magnetic fields they generate (subject <span class="hlt">eddy</span> fields). The inverse problem of obtaining conductivity distribution from subject <span class="hlt">eddy</span> fields was formulated as a convection-reaction partial differential equation. For measuring subject <span class="hlt">eddy</span> fields, a modified spin-echo pulse sequence was used to determine the contribution of subject <span class="hlt">eddy</span> fields to MR phase images. In the simulations, successful conductivity reconstructions were obtained by solving the derived convection-reaction equation, suggesting that the proposed reconstruction algorithm performs well under ideal conditions. However, the level of the calculated phase due to the subject <span class="hlt">eddy</span> field in a representative object indicates that this phase is below the noise level and cannot be measured with an uncertainty sufficiently low for accurate conductivity reconstruction. Furthermore, some artifacts other than random noise were observed in the measured phases, which are discussed in relation to the effects of system imperfections during readout. Low-frequency conductivity imaging does not seem feasible using basic pulse sequences such as spin-echo on a clinical MRI scanner. Magn Reson Med 77:1926-1937, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1912842I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1912842I"><span>Distribution of the near-inertial kinetic energy inside mesoscale <span class="hlt">eddies</span>: Observations in the Gulf of Mexico</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ixetl Garcia Gomez, Beatriz; Pallas Sanz, Enric; Candela Perez, Julio</p> <p>2017-04-01</p> <p>The near-inertial oscillations (NIOs), generated by the wind stress on the surface mixed layer, are the inertia gravity waves with the lowest frequency and the highest kinetic energy. NIOs are important because they drive vertical mixing in the interior ocean during wave breaking events. Although the interaction between NIOs and mesoscale <span class="hlt">eddies</span> has been reported by several authors, these studies are mostly analytical and numerical, and only few observational studies have attempted to show the differences in near-inertial kinetic energy (KEi) between anticyclonic and cyclonic <span class="hlt">eddies</span>. In this work the spatial structure of the KEi inside the mesoscale <span class="hlt">eddies</span> is computed using daily satellite altimetry and observations of horizontal velocity from 23 moorings equipped with acoustic Doppler current profilers in the western Gulf of Mexico. Consistent to theory, the obtained four-year KEi-composites show two times more KEi inside the anticyclonic <span class="hlt">eddies</span> than inside the cyclonic ones. The vertical and horizontal cross-sections of the KEi-composites show that the KEi is mainly located near to the surface of the cyclonic <span class="hlt">eddies</span> (positive vorticity), whereas the KEi in anticyclonic <span class="hlt">eddies</span> (negative vorticity) is maximum in the <span class="hlt">eddy</span>'s center near to the base of the <span class="hlt">eddy</span> where the NIOs become more inertial, are trapped, and amplified. The mean vertical profiles show that the cyclonic <span class="hlt">eddies</span> present a maximum of KEi near to the surface at 50, while the maximum of KEi in the anticyclonic <span class="hlt">eddies</span> occurs between 900 and 1100 m. Inside anticyclonic <span class="hlt">eddies</span> another two relative maximums are observed, one in the mixed layer and the second at 300 m. In contrast, the mean profile of KEi outside the mesoscale <span class="hlt">eddies</span> has the maximum value at the surface ( 50 m), with high values of KEi in the first 200 m and negligible energy beneath that depth. A different mean distribution of the KEi is observed depending on the type of wind generator: tropical storms or unidirectional wind.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOSPO14D2848H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOSPO14D2848H"><span>Evaluation of an <span class="hlt">eddy</span> resolving global model at the Bermuda Atlantic Time-series Study site</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hiron, L.; Goncalves Neto, A.; Bates, N. R.; Johnson, R. J.</p> <p>2016-02-01</p> <p>The Bermuda Atlantic Time-series Study (BATS) commenced monthly sampling in 1988 and thus provides an invaluable 27 years of ocean temperature and salinity profiles for inferring climate relevant processes. However, the passage of mesoscale <span class="hlt">eddies</span> through this site complicates the local heat and salinity budgets due to inadequate spatial and temporal sampling of these <span class="hlt">eddy</span> systems. Thus, application of high resolution operational numerical models potentially offers a framework for estimating the horizontal transport due to mesoscale processes. The goal of this research was to analyze the accuracy of the MERCATOR operational 1/12° global ocean model at the BATS site by comparing temperature, salinity and heat budgets for years 2008 - 2015. Overall agreement in the upper 540m for temperature and salinity is found to be very encouraging with significant (P< 0.01) <span class="hlt">correlations</span> at all depths for both fields. The highest value of <span class="hlt">correlation</span> coefficient for the temperature field is 0.98 at the surface which decreases to 0.66 at 150m and then reaches a minimum of 0.50 at 320 to 540m. Similarly, the highest <span class="hlt">correlation</span> coefficient for salinity is found at the surface, with a value of 0.83 and then decreases to a minimum of 0.25 in the subtropical mode water though then increases to 0.5 at 540m. Mixing in the MERCATOR model is also very well captured with a mixed layer depth (MLD) <span class="hlt">correlation</span> coefficient of 0.92 for the seven year period. Finally, the total heat budget (0-540m) from MERCATOR varies coherently with the BATS observations as shown by a high <span class="hlt">correlation</span> coefficient of 0.84 (P < 0.01). According to these analyses, daily output from the MERCATOR model represents accurately the temperature, salinity, heat budget and MLD at the BATS site. We propose this model can be used in future research at the BATS site by providing information about mesoscale structure and importantly, advective fluxes at this site.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012AGUFMOS31H..06T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012AGUFMOS31H..06T"><span>Observed and Simulated <span class="hlt">Eddy</span> Diffusivity Upstream of the Drake Passage</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Tulloch, R.; Ferrari, R. M.; Marshall, J.</p> <p>2012-12-01</p> <p>Estimates of <span class="hlt">eddy</span> diffusivity in the Southern Ocean are poorly constrained due to lack of observations. We compare the first direct estimate of isopycnal <span class="hlt">eddy</span> diffusivity upstream of the Drake Passage (from Ledwell et al. 2011) with a numerical simulation. The estimate is computed from a point tracer release as part of the Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES). We find that the observational diffusivity estimate of about 500m^2/s at 1500m depth is close to that computed in a data-constrained, 1/20th of a degree simulation of the Drake Passage region. This tracer estimate also agrees with Lagrangian float calculations in the model. The role of mean flow suppression of <span class="hlt">eddy</span> diffusivity at shallower depths will also be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JPhCS1015e2005D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JPhCS1015e2005D"><span>Research of Steel-dielectric Transition Using Subminiature <span class="hlt">Eddy</span>-current Transducer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dmitriev, S. F.; Malikov, V. N.; Sagalakov, A. M.; Ishkov, A. V.</p> <p>2018-05-01</p> <p>The research aims to develop a subminiature transducer for electrical steel investigation. The authors determined the capability to study steel characteristics at different depths based on variations of <span class="hlt">eddy</span>-current transducer amplitude at the steel-dielectric boundary. A subminiature transformer-type transducer was designed, which enables to perform local investigations of ferromagnetic materials using an <span class="hlt">eddy</span>-current method based on local studies of the steel electrical conductivity. Having the designed transducer as a basis, a hardware-software complex was built to perform experimental studies of steel at the interface boundary. Test results are reported for a specimen with continuous and discrete measurements taken at different frequencies. The article provides the key technical information about the <span class="hlt">eddy</span> current transformer used and describes the methodology of measurements that makes it possible to control steel to dielectric transition.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017AIPA....7h5105W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017AIPA....7h5105W"><span>Motion-induced <span class="hlt">eddy</span> current thermography for high-speed inspection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wu, Jianbo; Li, Kongjing; Tian, Guiyun; Zhu, Junzhen; Gao, Yunlai; Tang, Chaoqing; Chen, Xiaotian</p> <p>2017-08-01</p> <p>This letter proposes a novel motion-induced <span class="hlt">eddy</span> current based thermography (MIECT) for high-speed inspection. In contrast to conventional <span class="hlt">eddy</span> current thermography (ECT) based on a time-varying magnetic field created by an AC coil, the motion-induced <span class="hlt">eddy</span> current is induced by the relative motion between magnetic field and inspected objects. A rotating magnetic field created by three-phase windings is used to investigate the heating principle and feasibility of the proposed method. Firstly, based on Faraday's law the distribution of MIEC is investigated, which is then validated by numerical simulation. Further, experimental studies are conducted to validate the proposed method by creating rotating magnetic fields at different speeds from 600 rpm to 6000 rpm, and it is verified that rotating speed will increase MIEC intensity and thereafter improve the heating efficiency. The conclusion can be preliminarily drawn that the proposed MIECT is a platform suitable for high-speed inspection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010PhRvS..13g0401K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010PhRvS..13g0401K"><span>Energy loss due to <span class="hlt">eddy</span> current in linear transformer driver cores</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, A. A.; Mazarakis, M. G.; Manylov, V. I.; Vizir, V. A.; Stygar, W. A.</p> <p>2010-07-01</p> <p>In linear transformer drivers [Phys. Rev. ST Accel. Beams 12, 050402 (2009)PRABFM1098-440210.1103/PhysRevSTAB.12.050402; Phys. Rev. ST Accel. Beams 12, 050401 (2009)PRABFM1098-440210.1103/PhysRevSTAB.12.050401] as well as any other linear induction accelerator cavities, ferromagnetic cores are used to prevent the current from flowing along the induction cavity walls which are in parallel with the load. But if the core is made of conductive material, the applied voltage pulse generates the <span class="hlt">eddy</span> current in the core itself which heats the core and therefore also reduces the overall linear transformer driver (LTD) efficiency. The energy loss due to generation of the <span class="hlt">eddy</span> current in the cores depends on the specific resistivity of the core material, the design of the core, as well as on the distribution of the <span class="hlt">eddy</span> current in the core tape during the remagnetizing process. In this paper we investigate how the <span class="hlt">eddy</span> current is distributed in a core tape with an arbitrary shape hysteresis loop. Our model is based on the textbook knowledge related to the <span class="hlt">eddy</span> current generation in ferromagnetics with rectangular hysteresis loop, and in usual conductors. For the reader’s convenience, we reproduce some most important details of this knowledge in our paper. The model predicts that the same core would behave differently depending on how fast the applied voltage pulse is: in the high frequency limit, the equivalent resistance of the core reduces during the pulse whereas in the low frequency limit it is constant. An important inference is that the energy loss due to the <span class="hlt">eddy</span> current generation can be reduced by increasing the cross section of the core over the minimum value which is required to avoid its saturation. The conclusions of the model are confirmed with experimental observations presented at the end of the paper.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5266280','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=5266280"><span>Enhanced Nitrogen Loss by <span class="hlt">Eddy</span>-Induced Vertical Transport in the Offshore Peruvian Oxygen Minimum Zone</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Callbeck, Cameron M.; Lavik, Gaute; Stramma, Lothar; Kuypers, Marcel M. M.; Bristow, Laura A.</p> <p>2017-01-01</p> <p>The eastern tropical South Pacific (ETSP) upwelling region is one of the ocean’s largest sinks of fixed nitrogen, which is lost as N2 via the anaerobic processes of anammox and denitrification. One-third of nitrogen loss occurs in productive shelf waters stimulated by organic matter export as a result of eastern boundary upwelling. Offshore, nitrogen loss rates are lower, but due to its sheer size this area accounts for ~70% of ETSP nitrogen loss. How nitrogen loss and primary production are regulated in the offshore ETSP region where coastal upwelling is less influential remains unclear. Mesoscale <span class="hlt">eddies</span>, ubiquitous in the ETSP region, have been suggested to enhance vertical nutrient transport and thereby regulate primary productivity and hence organic matter export. Here, we investigated the impact of mesoscale <span class="hlt">eddies</span> on anammox and denitrification activity using 15N-labelled in situ incubation experiments. Anammox was shown to be the dominant nitrogen loss process, but varied across the <span class="hlt">eddy</span>, whereas denitrification was below detection at all stations. Anammox rates at the <span class="hlt">eddy</span> periphery were greater than at the center. Similarly, depth-integrated chlorophyll paralleled anammox activity, increasing at the periphery relative to the <span class="hlt">eddy</span> center; suggestive of enhanced organic matter export along the periphery supporting nitrogen loss. This can be attributed to enhanced vertical nutrient transport caused by an <span class="hlt">eddy</span>-driven submesoscale mechanism operating at the <span class="hlt">eddy</span> periphery. In the ETSP region, the widespread distribution of <span class="hlt">eddies</span> and the large heterogeneity observed in anammox rates from a compilation of stations suggests that <span class="hlt">eddy</span>-driven vertical nutrient transport may regulate offshore primary production and thereby nitrogen loss. PMID:28122044</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AIPC..615..445P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AIPC..615..445P"><span>Conductivity tomography based on pulsed <span class="hlt">eddy</span> current with SQUID magnetometer</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Panaitov, G. I.; Krause, H.-J.; Zhang, Y.</p> <p>2002-05-01</p> <p>Pulsed <span class="hlt">eddy</span> current (EC) <span class="hlt">techniques</span> have the advantage of potentially covering a broader depth range than standard single frequency EC testing. We developed a novel pulsed EC <span class="hlt">technique</span> using a liquid-nitrogen cooled SQUID magnetometer. For two reasons, SQUID magnetometers are particularly well suited as sensors: first they constitute an extremely sensitive magnetic field sensor, second they measure the field directly which decays more slowly than its time derivative picked up by induction coils. A square waveform transmitter signal was used, with alternating slopes in order to eliminate drift effect, and stacking synchronous to the power line frequency in order to improve signal-to-noise. The early time (high frequency) data of the recorded transient correspond to the upper layers of the conducting medium, while late time data or low frequencies deliver information on deep layers. Measurements of cracks at different depths in a stacked aluminum sample are presented. From the measured data, the apparent conductivity of the sample was calculated for each position and depth by applying a <span class="hlt">technique</span> known from geophysical data interpretation. Thus, the position and depth of the crack was determined from the tomographic conductivity image of the sample.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017DyAtO..79...43T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017DyAtO..79...43T"><span>Variability of the Somali Current and <span class="hlt">eddies</span> during the southwest monsoon regimes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Trott, Corinne B.; Subrahmanyam, Bulusu; Murty, V. S. N.</p> <p>2017-09-01</p> <p>The meso-scale <span class="hlt">eddies</span> and currents in the Arabian Sea are analyzed using different satellite observations, Simple Oceanic Data Assimilation (SODA) reanalysis, and Ocean Reanalysis System 4 (ORAS4) from 1993 to 2016 to investigate the impacts of Southwest (SW) Monsoon strength on Somali Current (SC) mesoscale circulations such as the Great Whirl (GW), the Socotra <span class="hlt">Eddy</span> (SE), the Southern Gyre (SG), and smaller <span class="hlt">eddies</span>. Increased Ekman pumping during stronger SW monsoons strengthens coastal upwelling along the Somali coast. The Arabian Sea basin-wide anticyclonic circulation and presence of the GW form mesoscale circulation patterns favourable to advection of upwelled waters eastward into the central Arabian Sea. In September, after the SW monsoon winds reach peak strength in July and August, a higher number of discrete anticyclonic <span class="hlt">eddies</span> with higher (> 20 cm) sea surface height anomalies develop in strong and normal intensity SW monsoon seasons than weaker SW monsoon seasons.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/29421088','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/29421088"><span>Anticyclonic <span class="hlt">eddies</span> increase accumulation of microplastic in the North Atlantic subtropical gyre.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Brach, Laurent; Deixonne, Patrick; Bernard, Marie-France; Durand, Edmée; Desjean, Marie-Christine; Perez, Emile; van Sebille, Erik; Ter Halle, Alexandra</p> <p>2018-01-01</p> <p>There are fundamental gaps in our understanding of the fates of microplastics in the ocean, which must be overcome if the severity of this pollution is to be fully assessed. The predominant pattern is high accumulation of microplastic in subtropical gyres. Using in situ measurements from the 7th Continent expedition in the North Atlantic subtropical gyre, data from satellite observations and models, we show how microplastic concentrations were up to 9.4 times higher in an anticyclonic <span class="hlt">eddy</span> explored, compared to the cyclonic <span class="hlt">eddy</span>. Although our sample size is small, this is the first suggestive evidence that mesoscale <span class="hlt">eddies</span> might trap, concentrate and potentially transport microplastics. As <span class="hlt">eddies</span> are known to congregate nutrients and organisms, this phenomenon should be considered with regards to the potential impact of plastic pollution on the ecosystem in the open ocean. Copyright © 2017 Elsevier Ltd. All rights reserved.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/27475575','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/27475575"><span>3D analysis of <span class="hlt">eddy</span> current loss in the permanent magnet coupling.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Zhu, Zina; Meng, Zhuo</p> <p>2016-07-01</p> <p>This paper first presents a 3D analytical model for analyzing the radial air-gap magnetic field between the inner and outer magnetic rotors of the permanent magnet couplings by using the Amperian current model. Based on the air-gap field analysis, the <span class="hlt">eddy</span> current loss in the isolation cover is predicted according to the Maxwell's equations. A 3D finite element analysis model is constructed to analyze the magnetic field spatial distributions and vector <span class="hlt">eddy</span> currents, and then the simulation results obtained are analyzed and compared with the analytical method. Finally, the current losses of two types of practical magnet couplings are measured in the experiment to compare with the theoretical results. It is concluded that the 3D analytical method of <span class="hlt">eddy</span> current loss in the magnet coupling is viable and could be used for the <span class="hlt">eddy</span> current loss prediction of magnet couplings.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/1184758','DOE-PATENT-XML'); return false;" href="https://www.osti.gov/servlets/purl/1184758"><span><span class="hlt">Eddy</span> current thickness measurement apparatus</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Rosen, Gary J.; Sinclair, Frank; Soskov, Alexander; Buff, James S.</p> <p>2015-06-16</p> <p>A sheet of a material is disposed in a melt of the material. The sheet is formed using a cooling plate in one instance. An exciting coil and sensing coil are positioned downstream of the cooling plate. The exciting coil and sensing coil use <span class="hlt">eddy</span> currents to determine a thickness of the solid sheet on top of the melt.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018GBioC..32..226F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018GBioC..32..226F"><span>Biogeochemical Role of Subsurface Coherent <span class="hlt">Eddies</span> in the Ocean: Tracer Cannonballs, Hypoxic Storms, and Microbial Stewpots?</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Frenger, Ivy; Bianchi, Daniele; Stührenberg, Carolin; Oschlies, Andreas; Dunne, John; Deutsch, Curtis; Galbraith, Eric; Schütte, Florian</p> <p>2018-02-01</p> <p>Subsurface <span class="hlt">eddies</span> are known features of ocean circulation, but the sparsity of observations prevents an assessment of their importance for biogeochemistry. Here we use a global <span class="hlt">eddying</span> (0.1°) ocean-biogeochemical model to carry out a census of subsurface coherent <span class="hlt">eddies</span> originating from eastern boundary upwelling systems (EBUS) and quantify their biogeochemical effects as they propagate westward into the subtropical gyres. While most <span class="hlt">eddies</span> exist for a few months, moving over distances of hundreds of kilometers, a small fraction (<5%) of long-lived <span class="hlt">eddies</span> propagates over distances greater than 1,000 km, carrying the oxygen-poor and nutrient-rich signature of EBUS into the gyre interiors. In the Pacific, transport by subsurface coherent <span class="hlt">eddies</span> accounts for roughly 10% of the offshore transport of oxygen and nutrients in pycnocline waters. This "leakage" of subsurface waters can be a significant fraction of the transport by nutrient-rich poleward undercurrents and may contribute to the well-known reduction of productivity by <span class="hlt">eddies</span> in EBUS. Furthermore, at the density layer of their cores, <span class="hlt">eddies</span> decrease climatological oxygen locally by close to 10%, thereby expanding oxygen minimum zones. Finally, <span class="hlt">eddies</span> represent low-oxygen extreme events in otherwise oxygenated waters, increasing the area of hypoxic waters by several percent and producing dramatic short-term changes that may play an important ecological role. Capturing these nonlocal effects in global climate models, which typically include noneddying oceans, would require dedicated parameterizations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMOS43C1285C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMOS43C1285C"><span>A Multi-wavenumber Theory for <span class="hlt">Eddy</span> Diffusivities: Applications to the DIMES Region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chen, R.; Gille, S. T.; McClean, J.; Flierl, G.; Griesel, A.</p> <p>2014-12-01</p> <p>Climate models are sensitive to the representation of ocean mixing processes. This has motivated recent efforts to collect observations aimed at improving mixing estimates and parameterizations. The US/UK field program Diapycnal and Isopycnal Mixing Experiment in the Southern Ocean (DIMES), begun in 2009, is providing such estimates upstream of and within the Drake Passage. This region is characterized by topography, and strong zonal jets. In previous studies, mixing length theories, based on the assumption that <span class="hlt">eddies</span> are dominated by a single wavenumber and phase speed, were formulated to represent the estimated mixing patterns in jets. However, in spite of the success of the single wavenumber theory in some other scenarios, it does not effectively predict the vertical structures of observed <span class="hlt">eddy</span> diffusivities in the DIMES area. Considering that <span class="hlt">eddy</span> motions encompass a wide range of wavenumbers, which all contribute to mixing, in this study we formulated a multi-wavenumber theory to predict <span class="hlt">eddy</span> mixing rates. We test our theory for a domain encompassing the entire Southern Ocean. We estimated <span class="hlt">eddy</span> diffusivities and mixing lengths from one million numerical floats in a global <span class="hlt">eddying</span> model. These float-based mixing estimates were compared with the predictions from both the single-wavenumber and the multi-wavenumber theories. Our preliminary results in the DIMES area indicate that, compared to the single-wavenumber theory, the multi-wavenumber theory better predicts the vertical mixing structures in the vast areas where the mean flow is weak; however in the intense jet region, both theories have similar predictive skill.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017EGUGA..1917050Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017EGUGA..1917050Z"><span>Mesoscale <span class="hlt">eddies</span> control meridional heat flux variability in the subpolar North Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhao, Jian; Bower, Amy; Yang, Jiayan; Lin, Xiaopei; Zhou, Chun</p> <p>2017-04-01</p> <p>The meridional heat flux in the subpolar North Atlantic is vital to the climate of the high-latitude North Atlantic. For the basinwide heat flux across a section between Greenland and Scotland, much of the variability occurs in the Iceland basin, where the North Atlantic Current (NAC) carries relatively warm and salty water northward. As a component of the Overturning in the Subpolar North Atlantic Program (OSNAP), WHOI and OUC are jointly operating gliders in the Iceland Basin to continuously monitor the circulation and corresponding heat flux in this <span class="hlt">eddy</span>-rich region. Based on one year of observations, two circulation regimes in the Iceland basin have been identified: a mesoscale <span class="hlt">eddy</span> like circulation pattern and northward NAC circulation pattern. When a mesoscale <span class="hlt">eddy</span> is generated, the rotational currents associated with the <span class="hlt">eddy</span> lead to both northward and southward flow in the Iceland basin. This is quite different from the broad northward flow associated with the NAC when there is no <span class="hlt">eddy</span>. The transition between the two regimes coupled with the strong temperature front in the Iceland basin can modify the meridional heat flux on the order of 0.3PW, which is the dominant source for the heat flux change the Iceland Basin. According to high-resolution numerical model results, the Iceland Basin has the largest contribution to the meridional heat flux variability along the section between Greenland and Scotland. Therefore, mesoscale <span class="hlt">eddies</span> in the Iceland Basin provide important dynamics to control the meridional heat flux variability in the subpolar North Atlantic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/servlets/purl/572689','SCIGOV-STC'); return false;" href="https://www.osti.gov/servlets/purl/572689"><span>Nondestructive inspection assessment of <span class="hlt">eddy</span> current and electrochemical analysis to separate inconel and stainless steel alloys</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Moore, D.G.; Sorensen, N.R.</p> <p>1998-02-01</p> <p>This report presents a nondestructive inspection assessment of <span class="hlt">eddy</span> current and electrochemical analysis to separate inconel alloys from stainless steel alloys as well as an evaluation of cleaning <span class="hlt">techniques</span> to remove a thermal oxide layer on aircraft exhaust components. The results of this assessment are presented in terms of how effective each <span class="hlt">technique</span> classifies a known exhaust material. Results indicate that either inspection <span class="hlt">technique</span> can separate inconel and stainless steel alloys. Based on the experiments conducted, the electrochemical spot test is the optimum for use by airframe and powerplant mechanics. A spot test procedure is proposed for incorporation into themore » Federal Aviation Administration Advisory Circular 65-9A Airframe & Powerplant Mechanic - General Handbook. 3 refs., 70 figs., 7 tabs.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930022371','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930022371"><span>An integrated <span class="hlt">eddy</span> current detection and imaging system on a silicon chip</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Henderson, H. Thurman; Kartalia, K. P.; Dury, Joseph D.</p> <p>1991-01-01</p> <p><span class="hlt">Eddy</span> current probes have been used for many years for numerous sensing applications including crack detection in metals. However, these applications have traditionally used the <span class="hlt">eddy</span> current effect in the form of a physically wound single or different probe pairs which of necessity must be made quite large compared to microelectronics dimensions. Also, the traditional wound probe can only take a point reading, although that point might include tens of individual cracks or crack arrays; thus, conventional <span class="hlt">eddy</span> current probes are beset by two major problems: (1) no detailed information can be obtained about the crack or crack array; and (2) for applications such as quality assurance, a vast amount of time must be taken to scan a complete surface. Laboratory efforts have been made to fabricate linear arrays of single turn probes in a thick film format on a ceramic substrate as well as in a flexible cable format; however, such efforts inherently suffer from relatively large size requirements as well as sensitivity issues. Preliminary efforts to fully extend <span class="hlt">eddy</span> current probing from a point or single dimensional level to a two dimensional micro-<span class="hlt">eddy</span> current format on a silicon chip, which might overcome all of the above problems, are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26703608','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26703608"><span>Fatigue Crack Length Sizing Using a Novel Flexible <span class="hlt">Eddy</span> Current Sensor Array.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Xie, Ruifang; Chen, Dixiang; Pan, Mengchun; Tian, Wugang; Wu, Xuezhong; Zhou, Weihong; Tang, Ying</p> <p>2015-12-21</p> <p>The <span class="hlt">eddy</span> current probe, which is flexible, array typed, highly sensitive and capable of quantitative inspection is one practical requirement in nondestructive testing and also a research hotspot. A novel flexible planar <span class="hlt">eddy</span> current sensor array for the inspection of microcrack presentation in critical parts of airplanes is developed in this paper. Both exciting and sensing coils are etched on polyimide films using a flexible printed circuit board <span class="hlt">technique</span>, thus conforming the sensor to complex geometric structures. In order to serve the needs of condition-based maintenance (CBM), the proposed sensor array is comprised of 64 elements. Its spatial resolution is only 0.8 mm, and it is not only sensitive to shallow microcracks, but also capable of sizing the length of fatigue cracks. The details and advantages of our sensor design are introduced. The working principal and the crack responses are analyzed by finite element simulation, with which a crack length sizing algorithm is proposed. Experiments based on standard specimens are implemented to verify the validity of our simulation and the efficiency of the crack length sizing algorithm. Experimental results show that the sensor array is sensitive to microcracks, and is capable of crack length sizing with an accuracy within ±0.2 mm.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li class="active"><span>24</span></li> <li><a href="#" onclick='return showDiv("page_25");'>25</a></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_24 --> <div id="page_25" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="481"> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4721828','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4721828"><span>Fatigue Crack Length Sizing Using a Novel Flexible <span class="hlt">Eddy</span> Current Sensor Array</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Xie, Ruifang; Chen, Dixiang; Pan, Mengchun; Tian, Wugang; Wu, Xuezhong; Zhou, Weihong; Tang, Ying</p> <p>2015-01-01</p> <p>The <span class="hlt">eddy</span> current probe, which is flexible, array typed, highly sensitive and capable of quantitative inspection is one practical requirement in nondestructive testing and also a research hotspot. A novel flexible planar <span class="hlt">eddy</span> current sensor array for the inspection of microcrack presentation in critical parts of airplanes is developed in this paper. Both exciting and sensing coils are etched on polyimide films using a flexible printed circuit board <span class="hlt">technique</span>, thus conforming the sensor to complex geometric structures. In order to serve the needs of condition-based maintenance (CBM), the proposed sensor array is comprised of 64 elements. Its spatial resolution is only 0.8 mm, and it is not only sensitive to shallow microcracks, but also capable of sizing the length of fatigue cracks. The details and advantages of our sensor design are introduced. The working principal and the crack responses are analyzed by finite element simulation, with which a crack length sizing algorithm is proposed. Experiments based on standard specimens are implemented to verify the validity of our simulation and the efficiency of the crack length sizing algorithm. Experimental results show that the sensor array is sensitive to microcracks, and is capable of crack length sizing with an accuracy within ±0.2 mm. PMID:26703608</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4501708','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4501708"><span>Enhanced Particulate Organic Carbon Export at <span class="hlt">Eddy</span> Edges in the Oligotrophic Western North Pacific Ocean</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Shih, Yung-Yen; Hung, Chin-Chang; Gong, Gwo-Ching; Chung, Wan-Chen; Wang, Yu-Huai; Lee, I-Huan; Chen, Kuo-Shu; Ho, Chuang-Yi</p> <p>2015-01-01</p> <p>Mesoscale <span class="hlt">eddies</span> in the subtropical oligotrophic ocean are ubiquitous and play an important role in nutrient supply and oceanic primary production. However, it is still unclear whether these mesoscale <span class="hlt">eddies</span> can efficiently transfer CO2 from the atmosphere to deep waters via biological pump because of the sampling difficulty due to their transient nature. In 2007, particulate organic carbon (POC) fluxes, measured below the euphotic zone at the edge of warm <span class="hlt">eddy</span> were 136–194 mg-C m−2 d−1 which was greatly elevated over that (POC flux = 26–35 mg-C m−2 d−1) determined in the nutrient-depleted oligotrophic waters in the Western North Pacific (WNP). In 2010, higher POC fluxes (83–115 mg-C m−2 d−1) were also observed at the boundary of mesoscale <span class="hlt">eddies</span> in the WNP. The enhanced POC flux at the edge of <span class="hlt">eddies</span> was mainly attributed to both large denuded diatom frustules and zooplankton fecal pellets based on scanning electron microscopy (SEM) examination. The result suggests that mesoscale <span class="hlt">eddies</span> in the oligotrophic waters in the subtropical WNP can efficiently increase the oceanic carbon export flux and the <span class="hlt">eddy</span> edge is a crucial conduit in carbon sequestration to deep waters. PMID:26171611</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ars.usda.gov/research/publications/publication/?seqNo115=312728','TEKTRAN'); return false;" href="http://www.ars.usda.gov/research/publications/publication/?seqNo115=312728"><span>Spectral analysis of large-<span class="hlt">eddy</span> advection in ET from <span class="hlt">eddy</span> covariance towers and a large weighting lysimeter</span></a></p> <p><a target="_blank" href="https://www.ars.usda.gov/research/publications/find-a-publication/">USDA-ARS?s Scientific Manuscript database</a></p> <p></p> <p></p> <p>Evapotranspiration was continuously measured by an array of <span class="hlt">eddy</span> covariance systems and large weighting lysimeter in a cotton field in Bushland, Texas. The advective divergence from both horizontal and vertical directions were measured through profile measurements above canopy. All storage terms wer...</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002AIPC..615..409Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002AIPC..615..409Y"><span>The interaction of pulsed <span class="hlt">eddy</span> current with metal surface crack for various coils</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yang, Hung-Chi; Tai, Cheng-Chi</p> <p>2002-05-01</p> <p>We study the interaction of pulsed <span class="hlt">eddy</span> current (PEC) with metal surface cracks using various coils that have different geometric sizes. In the previous work, we have showed that the PEC <span class="hlt">technique</span> can be used to inspect electrical-discharge-machined (EDM) notches with depth from 0.5 mm to 9 mm. The results showed that the relationship between PEC signals and crack depth is obvious. In this work, we further try a series of coils with different radii, heights, turns and shapes. We will discuss the effects of these coil parameters on the PEC signal. Some other critical problems of PEC measurements such as signal drift that caused by heating effect of coil currents will be studied. We also show more experiments on fatigue cracks to demonstrate the capability of PEC <span class="hlt">technique</span> for cracks inspection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://ntrs.nasa.gov/search.jsp?R=19840000231&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DEddy%2Bcurrent','NASA-TRS'); return false;" href="https://ntrs.nasa.gov/search.jsp?R=19840000231&hterms=Eddy+current&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DEddy%2Bcurrent"><span>Differential-Coil <span class="hlt">Eddy</span>-Current Material Sorter</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Nummelin, J.; Buckley, D.</p> <p>1985-01-01</p> <p>Small metal or other electrically conductive parts of same shape but different composition quickly sorted with differential-coil <span class="hlt">eddy</span>-current sorter. Developed to distinguish between turbine blades of different alloys, hardnesses, and residual stress, sorter generally applicable to parts of simple and complex shape.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018RuPhJ..60.1880S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018RuPhJ..60.1880S"><span>Magnetic Field of Conductive Objects as Superposition of Elementary <span class="hlt">Eddy</span> Currents and <span class="hlt">Eddy</span> Current Tomography</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sukhanov, D. Ya.; Zav'yalova, K. V.</p> <p>2018-03-01</p> <p>The paper represents induced currents in an electrically conductive object as a totality of elementary <span class="hlt">eddy</span> currents. The proposed scanning method includes measurements of only one component of the secondary magnetic field. Reconstruction of the current distribution is performed by deconvolution with regularization. Numerical modeling supported by the field experiments show that this approach is of direct practical relevance.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://eric.ed.gov/?q=Eddy+AND+current&pg=3&id=ED012565','ERIC'); return false;" href="https://eric.ed.gov/?q=Eddy+AND+current&pg=3&id=ED012565"><span>MATERIALS AND <span class="hlt">TECHNIQUES</span> FOR THE LANGUAGE LABORATORY.</span></a></p> <p><a target="_blank" href="http://www.eric.ed.gov/ERICWebPortal/search/extended.jsp?_pageLabel=advanced">ERIC Educational Resources Information Center</a></p> <p>NAJAM, EDWARD W.</p> <p></p> <p>THE PROCEEDINGS OF THE SECOND ANNUAL INDIANA-PURDUE LANGUAGE LABORATORY CONFERENCE ARE ORGANIZED, AFTER INTRODUCTORY STATEMENTS BY NAJAM AND LARSEN ON CONTEMPORARY TRENDS IN LANGUAGE INSTRUCTION, UNDER THREE GENERAL HEADINGS PLUS APPENDIXES. IN THE FIRST SECTION DEVOTED TO MATERIALS AND <span class="hlt">TECHNIQUES</span> ARE ARTICLES BY HYER, GARIMALDI, <span class="hlt">EDDY</span>, AND SMITH…</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/16376361','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/16376361"><span><span class="hlt">Eddies</span> in a bottleneck: an arbitrary Debye length theory for capillary electroosmosis.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Park, Stella Y; Russo, Christopher J; Branton, Daniel; Stone, Howard A</p> <p>2006-05-15</p> <p>Using an applied electrical field to drive fluid flows becomes desirable as channels become smaller. Although most discussions of electroosmosis treat the case of thin Debye layers, here electroosmotic flow (EOF) through a constricted cylinder is presented for arbitrary Debye lengths (kappa(-1)) using a long wavelength perturbation of the cylinder radius. The analysis uses the approximation of small potentials. The varying diameter of the cylinder produces radially and axially varying effective electric fields, as well as an induced pressure gradient. We predict the existence of <span class="hlt">eddies</span> for certain constricted geometries and propose the possibility of electrokinetic trapping in these regions. We also present a leading-order criterion which predicts central <span class="hlt">eddies</span> in very narrow constrictions at the scale of the Debye length. <span class="hlt">Eddies</span> can be found both in the center of the channel and along the perimeter, and the presence of the <span class="hlt">eddies</span> is a consequence of the induced pressure gradient that accompanies electrically driven flow into a narrow constriction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3174066','PMC'); return false;" href="https://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=3174066"><span><span class="hlt">Eddies</span> in a Bottleneck: An Arbitrary Debye Length Theory for Capillary Electroosmosis</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Park, Stella Y.; Russo, Christopher J.; Branton, Daniel; Stone, Howard A.</p> <p>2011-01-01</p> <p>Using an applied electrical field to drive fluid flows becomes desirable as channels become smaller. Although most discussions of electroosmosis treat the case of thin Debye layers, here electroosmotic flow (EOF) through a constricted cylinder is presented for arbitrary Debye lengths (κ−1) using a long wavelength perturbation of the cylinder radius. The analysis uses the approximation of small potentials. The varying diameter of the cylinder produces radially and axially varying effective electric fields, as well as an induced pressure gradient. We predict the existence of <span class="hlt">eddies</span> for certain constricted geometries and propose the possibility of electrokinetic trapping in these regions. We also present a leading-order criterion which predicts central <span class="hlt">eddies</span> in very narrow constrictions at the scale of the Debye length. <span class="hlt">Eddies</span> can be found both in the center of the channel and along the perimeter, and the presence of the <span class="hlt">eddies</span> is a consequence of the induced pressure gradient that accompanies electrically driven flow into a narrow constriction. PMID:16376361</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/26329187','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/26329187"><span>Measurement of <span class="hlt">eddy</span>-current distribution in the vacuum vessel of the Sino-UNIted Spherical Tokamak.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Li, G; Tan, Y; Liu, Y Q</p> <p>2015-08-01</p> <p><span class="hlt">Eddy</span> currents have an important effect on tokamak plasma equilibrium and control of magneto hydrodynamic activity. The vacuum vessel of the Sino-UNIted Spherical Tokamak is separated into two hemispherical sections by a toroidal insulating barrier. Consequently, the characteristics of <span class="hlt">eddy</span> currents are more complex than those found in a standard tokamak. Thus, it is necessary to measure and analyze the <span class="hlt">eddy</span>-current distribution. In this study, we propose an experimental method for measuring the <span class="hlt">eddy</span>-current distribution in a vacuum vessel. By placing a flexible printed circuit board with magnetic probes onto the external surface of the vacuum vessel to measure the magnetic field parallel to the surface and then subtracting the magnetic field generated by the vertical-field coils, the magnetic field due to the <span class="hlt">eddy</span> current can be obtained, and its distribution can be determined. We successfully applied this method to the Sino-UNIted Spherical Tokamak, and thus, we obtained the <span class="hlt">eddy</span>-current distribution despite the presence of the magnetic field generated by the external coils.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017Ocgy...57..350Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017Ocgy...57..350Z"><span><span class="hlt">Eddy</span> formation behind a coastal cape in a flow generated by transient longshore wind (Numerical experiments)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhurbas, V. M.; Kuzmina, N. P.; Lyzhkov, D. A.</p> <p>2017-05-01</p> <p>It is shown that the process of <span class="hlt">eddy</span> formation behind a coastal cape essentially depends on the method by which longshore flow is generated. Numerical simulations of the flow around a cape generated by transient longshore wind have revealed different modes of <span class="hlt">eddy</span> formation in a rotating stratified environment depending on such dimensionless parameters as the Burger and Kibel-Rossby numbers, Bu and Ro, respectively. At Ro < 0.6, depending on the magnitude of Bu, either a trapped anticyclonic or cyclonic <span class="hlt">eddy</span> (at Bu < 0.2) or periodic <span class="hlt">eddy</span> shedding (at Bu < 0.2) forms. The <span class="hlt">eddies</span> are weakened and stretched along the coastline at 0.4-0.6 < Ro < 1.4 and ultimately disappear at Ro < 1.4.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.ncbi.nlm.nih.gov/pubmed/19272885','PUBMED'); return false;" href="https://www.ncbi.nlm.nih.gov/pubmed/19272885"><span>A new method for electric impedance imaging using an <span class="hlt">eddy</span> current with a tetrapolar circuit.</span></a></p> <p><a target="_blank" href="https://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Ahsan-Ul-Ambia; Toda, Shogo; Takemae, Tadashi; Kosugi, Yukio; Hongo, Minoru</p> <p>2009-02-01</p> <p>A new contactless <span class="hlt">technique</span> for electrical impedance imaging, using an <span class="hlt">eddy</span> current managed along with the tetrapolar circuit method, is proposed. The <span class="hlt">eddy</span> current produced by a magnetic field is superimposed on a constant current that is normally used in the tetrapolar circuit method, and thus is used to control the current distribution in the body. By changing the current distribution, a set of voltage differences is measured with a pair of electrodes. This set of voltage differences is used in the image reconstruction of the resistivity distribution. The least square error minimization method is used in the reconstruction algorithm. The principle of this method is explained theoretically. A backprojection algorithm was used to get 2-D images. Based on this principle, a measurement system was developed and model experiments were conducted with a saline-filled phantom. The estimated shape of each model in the reconstructed image was similar to that of the corresponding model. From the results of these experiments, it is confirmed that the proposed method is applicable to the realization of electrical conductivity imaging.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750000309','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750000309"><span>Foam-machining tool with <span class="hlt">eddy</span>-current transducer</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Copper, W. P.</p> <p>1975-01-01</p> <p>Three-cutter machining system for foam-covered tanks incorporates <span class="hlt">eddy</span>-current sensor. Sensor feeds signal to numerical controller which programs rotational and vertical axes of sensor travel, enabling cutterhead to profile around tank protrusions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013JGRC..118..301M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013JGRC..118..301M"><span>A numerical modeling study of the East Australian Current encircling and overwashing a warm-core <span class="hlt">eddy</span></span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>MacDonald, H. S.; Roughan, M.; Baird, M. E.; Wilkin, J.</p> <p>2013-01-01</p> <p><title type="main">AbstractWarm-core <span class="hlt">eddies</span> (WCEs) often form in the meanders of Western Boundary Currents (WBCs). WCEs are frequently overwashed with less dense waters sourced from the WBC. We use the Regional Ocean Modelling System to investigate the ocean state during the overwashing of one such WCE in October 2008 in the East Australian Current (EAC). Comparisons of model outputs with satellite sea surface temperature and vertical profiles show that the model provides a realistic simulation of the <span class="hlt">eddy</span> during the period when the EAC encircled and then overwashed the <span class="hlt">eddy</span>. During the encircling stage, an <span class="hlt">eddy</span> with closed circulation persisted at depth. In the surface EAC water entered from the north, encircled the <span class="hlt">eddy</span> and exited to the east. The overwashing stage was initiated by the expulsion of cyclonic vorticity. For the following 8 days after the expulsion, waters from the EAC washed over the top of the <span class="hlt">eddy</span>, transferring heat and anticyclonic vorticity radially-inward. After approximately one rotation period of overwashing, the <span class="hlt">eddy</span> separated. The overwashing creates a two-layer system that forms a subsurface maximum velocity at the interface of the two layers. Analysis of water mass properties, Eulerian tracer dynamics, and Lagrangian particle tracks show that the original <span class="hlt">eddy</span> sinks 10-50 m during the overwashing period. Overwashing has been observed in many WBCs and occurs in most WCEs in the western Tasman Sea.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('https://www.osti.gov/biblio/1230534-electromagnetics-eddy-current-computer-codes','SCIGOV-STC'); return false;" href="https://www.osti.gov/biblio/1230534-electromagnetics-eddy-current-computer-codes"><span>electromagnetics, <span class="hlt">eddy</span> current, computer codes</span></a></p> <p><a target="_blank" href="http://www.osti.gov/search">DOE Office of Scientific and Technical Information (OSTI.GOV)</a></p> <p>Gartling, David</p> <p></p> <p>TORO Version 4 is designed for finite element analysis of steady, transient and time-harmonic, multi-dimensional, quasi-static problems in electromagnetics. The code allows simulation of electrostatic fields, steady current flows, magnetostatics and <span class="hlt">eddy</span> current problems in plane or axisymmetric, two-dimensional geometries. TORO is easily coupled to heat conduction and solid mechanics codes to allow multi-physics simulations to be performed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015BGD....1214175L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015BGD....1214175L"><span>Hidden biosphere in an oxygen-deficient Atlantic open ocean <span class="hlt">eddy</span>: future implications of ocean deoxygenation on primary production in the eastern tropical North Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Löscher, C. R.; Fischer, M. A.; Neulinger, S. C.; Fiedler, B.; Philippi, M.; Schütte, F.; Singh, A.; Hauss, H.; Karstensen, J.; Körtzinger, A.; Künzel, S.; Schmitz, R. A.</p> <p>2015-08-01</p> <p>The eastern tropical North Atlantic (ETNA) is characterized by a highly productive coastal upwelling system and a moderate oxygen minimum zone with lowest open ocean oxygen (O2) concentrations of around 40 μmol kg-1. Only recently, the discovery of re-occurring mesoscale <span class="hlt">eddies</span> with sometimes close to anoxic O2 concentrations (<1 μmol kg-1) and located just below the mixed layer challenged our understanding of O2 distribution and biogeochemical processes in this area. Here, we present the first metagenomic dataset from a deoxygenated anticyclonic modewater <span class="hlt">eddy</span> in the open waters of the ETNA. In the <span class="hlt">eddy</span>, we observed a significantly lower bacterial diversity compared to surrounding waters, along with a significant community shift. We detected enhanced primary productivity in the surface layer of the <span class="hlt">eddy</span> indicated by elevated chlorophyll concentrations and increased carbon uptake rates up to three times as high as in surrounding waters. Carbon uptake below the euphotic zone <span class="hlt">correlated</span> to the presence of a specific high-light ecotype of Prochlorococcus, which is usually underrepresented in the ETNA. Our combined data indicate that high primary production in the <span class="hlt">eddy</span> fuels export production and the presence of a specific microbial community responsible for enhanced respiration at shallow depths, below the mixed layer base. Progressively decreasing O2 concentrations in the <span class="hlt">eddy</span> were found to promote transcription of the key gene for denitrification, nirS, in the O2-depleted core waters. This process is usually absent from the open ETNA waters. In the light of future ocean deoxygenation our results show exemplarily that even distinct events of anoxia have the potential to alter microbial community structures and with that critically impact primary productivity and biogeochemical processes of oceanic water bodies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2018JGRC..123..497Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2018JGRC..123..497Z"><span>Impacts of Mesoscale <span class="hlt">Eddies</span> on the Vertical Nitrate Flux in the Gulf Stream Region</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Shuwen; Curchitser, Enrique N.; Kang, Dujuan; Stock, Charles A.; Dussin, Raphael</p> <p>2018-01-01</p> <p>The Gulf Stream (GS) region has intense mesoscale variability that can affect the supply of nutrients to the euphotic zone (Zeu). In this study, a recently developed high-resolution coupled physical-biological model is used to conduct a 25-year simulation in the Northwest Atlantic. The Reynolds decomposition method is applied to quantify the nitrate budget and shows that the mesoscale variability is important to the vertical nitrate supply over the GS region. The decomposition, however, cannot isolate <span class="hlt">eddy</span> effects from those arising from other mesoscale phenomena. This limitation is addressed by analyzing a large sample of <span class="hlt">eddies</span> detected and tracked from the 25-year simulation. The <span class="hlt">eddy</span> composite structures indicate that positive nitrate anomalies within Zeu exist in both cyclonic <span class="hlt">eddies</span> (CEs) and anticyclonic <span class="hlt">eddies</span> (ACEs) over the GS region, and are even more pronounced in the ACEs. Our analysis further indicates that positive nitrate anomalies mostly originate from enhanced vertical advective flux rather than vertical turbulent diffusion. The <span class="hlt">eddy</span>-wind interaction-induced Ekman pumping is very likely the mechanism driving the enhanced vertical motions and vertical nitrate transport within ACEs. This study suggests that the ACEs in GS region may play an important role in modulating the oceanic biogeochemical properties by fueling local biomass production through the persistent supply of nitrate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2017JGRC..122.6725B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2017JGRC..122.6725B"><span>Testing Munk's hypothesis for submesoscale <span class="hlt">eddy</span> generation using observations in the North Atlantic</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Buckingham, Christian E.; Khaleel, Zammath; Lazar, Ayah; Martin, Adrian P.; Allen, John T.; Naveira Garabato, Alberto C.; Thompson, Andrew F.; Vic, Clément</p> <p>2017-08-01</p> <p>A high-resolution satellite image that reveals a train of coherent, submesoscale (6 km) vortices along the edge of an ocean front is examined in concert with hydrographic measurements in an effort to understand formation mechanisms of the submesoscale <span class="hlt">eddies</span>. The infrared satellite image consists of ocean surface temperatures at ˜390 m resolution over the midlatitude North Atlantic (48.69°N, 16.19°W). Concomitant altimetric observations coupled with regular spacing of the <span class="hlt">eddies</span> suggest the <span class="hlt">eddies</span> result from mesoscale stirring, filamentation, and subsequent frontal instability. While horizontal shear or barotropic instability (BTI) is one mechanism for generating such <span class="hlt">eddies</span> (Munk's hypothesis), we conclude from linear theory coupled with the in situ data that mixed layer or submesoscale baroclinic instability (BCI) is a more plausible explanation for the observed submesoscale vortices. Here we assume that the frontal disturbance remains in its linear growth stage and is accurately described by linear dynamics. This result likely has greater applicability to the open ocean, i.e., regions where the gradient Rossby number is reduced relative to its value along coasts and within strong current systems. Given that such waters comprise an appreciable percentage of the ocean surface and that energy and buoyancy fluxes differ under BTI and BCI, this result has wider implications for open-ocean energy/buoyancy budgets and parameterizations within ocean general circulation models. In summary, this work provides rare observational evidence of submesoscale <span class="hlt">eddy</span> generation by BCI in the open ocean.<abstract type="synopsis"><title type="main">Plain Language SummaryHere, we test Munk's theory for small-scale <span class="hlt">eddy</span> generation using a unique set of satellite- and ship-based observations. We find that for one particular set of observations in the North Atlantic, the mechanism for <span class="hlt">eddy</span> generation is not pure horizontal shear, as proposed by Munk et al. (<link href="#jgrc22402-bib</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.1960G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.1960G"><span><span class="hlt">Eddy</span>-covariance methane flux measurements over a European beech forest</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Gentsch, Lydia; Siebicke, Lukas; Knohl, Alexander</p> <p>2015-04-01</p> <p>The role of forests in global methane (CH4) turnover is currently not well constrained, partially because of the lack of spatially integrative forest-scale measurements of CH4 fluxes. Soil chamber measurements imply that temperate forests generally act as CH4 sinks. Upscaling of chamber observations to the forest scale is however problematic, if the upscaling is not constrained by concurrent 'top-down' measurements, such as of the <span class="hlt">eddy</span>-covariance type, which provide sufficient integration of spatial variations and of further potential CH4 flux components within forest ecosystems. Ongoing development of laser absorption-based optical instruments, resulting in enhanced measurement stability, precision and sampling speed, has recently improved the prospects for meaningful <span class="hlt">eddy</span>-covariance measurements at sites with presumably low CH4 fluxes, hence prone to reach the flux detection limit. At present, we are launching <span class="hlt">eddy</span>-covariance CH4 measurements at a long-running ICOS flux tower site (Hainich National Park, Germany), located in a semi natural, unmanaged, beech dominated forest. <span class="hlt">Eddy</span>-covariance measurements will be conducted with a laser spectrometer for parallel CH4, H2Ov and CO2 measurements (FGGA, Los Gatos Research, USA). Independent observations of the CO2 flux by the FGGA and a standard Infrared Gas Analyser (LI-7200, LI-COR, USA) will allow to evaluate data quality of measured CH4 fluxes. Here, we want to present first results with a focus on uncertainties of the calculated CH4 fluxes with regard to instrument precision, data processing and site conditions. In future, we plan to compare <span class="hlt">eddy</span>-covariance flux estimates to side-by-side turbulent flux observations from a novel <span class="hlt">eddy</span> accumulation system. Furthermore, soil CH4 fluxes will be measured with four automated chambers situated within the tower footprint. Based on a previous soil chamber study at the same site, we expect the Hainich forest site to act as a CH4 sink. However, we hypothesize that our</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AGUOS.B44B0389T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AGUOS.B44B0389T"><span><span class="hlt">Eddy</span> Mediated Nutrient Pattern in the North Eastern Arabian Sea</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thachaparambil, M.; Moolakkal Antony, R.; B R, S.; V N, S.; N, C.; M, S.</p> <p>2016-02-01</p> <p>A Cold Core <span class="hlt">Eddy</span> (CCE) mediated nutrient pattern in the North Eastern Arabian Sea (NEAS) is explained based on in situ measurments during March 2013 onboard FORV Sagar Sampada which was not reported earlier in the area. Samples for physical, chemical and biological parameters were collected in 5 stations along the diameter of the <span class="hlt">eddy</span> and following standard protocols. The core of the CCE is identified at 21°20.38'N; 66°30.68'E with a diameter of 120Km. Earlier studies explaining the process and the forcing mechanism of the particular <span class="hlt">eddy</span> records that, the <span class="hlt">eddy</span> is short term (1-3 months) and is regular during the season. Surface waters were well oxygenated (>4.8 ml L-1) in the core. Surface value of nutrients viz., Nitrate, Nitrite, Silicate and phosphate in the core regions was 0.9µM, 0.01 µM, 0.5 µM and 0.7 µM respectively indicating upwelling in the core. Spring intermonsoon (SIM) is generally termed as a transition period between the active winter and summer seasons and as per earlier studies, high biological production and the regularly occurring Noctilica bloom is supported by the nutrient loading due to convective mixing during winter as well as regenerated production. However, present observations shows that, nutrient pumping due to the upwelling associated with the CCE also contributes for sustaining high biological production and are evident in the Chl a and mesozooplankton biovolume which records values of 4.35mg/m3 and 1.09ml/m3 respectively in the core. An intense Noctiluca blooms observed in the western flank of the <span class="hlt">eddy</span> (Chl a 13.25 mg/m3; cell density 5.8×106 cells/litre), where Nitrate concentration records 1.04µM explains the role of such mesoscale processes in the sustenance of the HAB events. While eastern flank of the CCE showed typical open ocean condition of the season showing Nitrate 0.08µM; Chl a 0.23mg/m3; and phytoplankton cell density as 421 cells/litre. Keywords: Cold core <span class="hlt">eddy</span>, nutrients, NEAS, SIM, biological production</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_21");'>21</a></li> <li><a href="#" onclick='return showDiv("page_22");'>22</a></li> <li><a href="#" onclick='return showDiv("page_23");'>23</a></li> <li><a href="#" onclick='return showDiv("page_24");'>24</a></li> <li class="active"><span>25</span></li> <li><a href="#" onclick='return showDiv("page_25");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_25 --> <div class="footer-extlink text-muted" style="margin-bottom:1rem; text-align:center;">Some links on this page may take you to non-federal websites. 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