Science.gov

Sample records for actual field measurements

  1. Meteorological field measurements at potential and actual wind turbine sites

    SciTech Connect

    Renne, D.S.; Sandusky, W.F.; Hadley, D.L.

    1982-09-01

    An overview of experiences gained in a meteorological measurement program conducted at a number of locations around the United States for the purpose of site evaluation for wind energy utilization is provided. The evolution of the measurement program from its inception in 1976 to the present day is discussed. Some of the major accomplishments and areas for improvement are outlined. Some conclusions on research using data from this program are presented.

  2. Assessment of actual transpiration rate in olive tree field combining sap-flow, leaf area index and scintillometer measurements

    NASA Astrophysics Data System (ADS)

    Agnese, C.; Cammalleri, C.; Ciraolo, G.; Minacapilli, M.; Provenzano, G.; Rallo, G.; de Bruin, H. A. R.

    2009-09-01

    Models to estimate the actual evapotranspiration (ET) in sparse vegetation area can be fundamental for agricultural water managements, especially when water availability is a limiting factor. Models validation must be carried out by considering in situ measurements referred to the field scale, which is the relevant scale of the modelled variables. Moreover, a particular relevance assumes to consider separately the components of plant transpiration (T) and soil evaporation (E), because only the first is actually related to the crop stress conditions. Objective of the paper was to assess a procedure aimed to estimate olive trees actual transpiration by combining sap flow measurements with the scintillometer technique at field scale. The study area, located in Western Sicily (Italy), is mainly cultivated with olive crop and is characterized by typical Mediterranean semi-arid climate. Measurements of sap flow and crop actual evapotranspiration rate were carried out during 2008 irrigation season. Crop transpiration fluxes, measured on some plants by means of sap flow sensors, were upscaled considering the leaf area index (LAI). The comparison between evapotranspiration values, derived by displaced-beam small-aperture scintillometer (DBSAS-SLS20, Scintec AG), with the transpiration fluxes obtained by the sap flow sensors, also allowed to evaluate the contribute of soil evaporation in an area characterized by low vegetation coverage.

  3. Evaluation of a total dissolved solids model in comparison to actual field data measurements in the Cheyenne River, South Dakota, U.S.A.

    PubMed

    Berdanier, Bruce W; Ziadat, Anf H

    2006-06-01

    During the summers of 2002 and 2004, in-stream integrated flow and concentration measurements for the total dissolved solids in the Cheyenne River, South Dakota, USA was conducted in order to compare the obtained actual field measurements with the predictions values made by the Bureau of Reclamation in the Environmental Impact Statement. In comparison to the actual field measurements conducted in this study, The Bureau of Reclamation extension of a small database used in the analysis for the impact of operations at the Angostura Unit over the past 50 years and into the future to predict the annual total dissolved solid loadings doesn't represent the actual loading values and various conditions in the study area. Additional integrated flow and concentration sampling is required to characterize the impact of the current Angostura Dam operations and Angostura Irrigation District return flows on the Cheyenne River in different seasons of the year. PMID:16917716

  4. Effect of soil type patterns on the variability of bare soil evaporation within a field: comparison of eddy covariance measurements with potential and actual evaporation calculations

    NASA Astrophysics Data System (ADS)

    Vanderborght, J.; Graf, A.; Steenpass, C.; Scharnagl, B.; Prolingheuer, N.; Herbst, M.; Vereecken, H.

    2009-12-01

    Bare soil evaporation was measured with the eddy-covariance method at the Selhausen field site. The site has a distinct gradient in soil texture with a considerably higher stone content at the upper part of the field. Because of this gradient, a spatial variation in evaporation fluxes in the field is expected. Because of the higher stone content at the upper part of the field, it is expected that the water that is stored in the soil surface layer and can be evaporated at a maximal evaporation rate, which is determined by the energy that is available for evaporation, is considerable smaller in the upper than in the lower part of the field. We investigated whether this hypothesis is supported by eddy covariance (EC) measurements of the evaporation fluxes at the field site. The EC measurements were combined with a footprint model that predicts the location of the soil surface that contributes to the measured evaporation flux. In this way, evaporation measurements of the two parts of the field site could be distinguished. However, since only one EC station was available, simultaneous evaporation measurements for the two field parts were not available. As a consequence, the datasets of measurements had to be interpreted and put into context of the meteorological and soil hydrological conditions. The potential evapotranspiration was calculated using the FAO method (Allen et al., 1998) to represent the meteorological conditions whereas a simple soil evaporation model (Boesten and Stroosnijder, 1986) was used to represent the influence of the precipitation and soil hydrological conditions on the actual evaporation rate. Since different soil parameters were required to describe the evaporation measurements for the upper and lower part of the plot, our starting hypothesis that more water is evaporated in the lower part of the field could be confirmed. Allen, R. G., L. S. Pereira, D. Raes, and M. Smith (1998), Crop evapotranspiration: Guidelines for computing crop water

  5. Estimation of Actual Crop ET of Paddy Using the Energy Balance Model SMARET and Validation with Field Water Balance Measurements and a Crop Growth Model (ORYZA)

    NASA Astrophysics Data System (ADS)

    Nallasamy, N. D.; Muraleedharan, B. V.; Kathirvel, K.; Narasimhan, B.

    2014-12-01

    Sustainable management of water resources requires reliable estimates of actual evapotranspiration (ET) at fine spatial and temporal resolution. This is significant in the case of rice based irrigation systems, one of the major consumers of surface water resources and where ET forms a major component of water consumption. However huge tradeoff in the spatial and temporal resolution of satellite images coupled with lack of adequate number of cloud free images within a growing season act as major constraints in deriving ET at fine spatial and temporal resolution using remote sensing based energy balance models. The scale at which ET is determined is decided by the spatial and temporal scale of Land Surface Temperature (LST) and Normalized Difference Vegetation Index (NDVI), which form inputs to energy balance models. In this context, the current study employed disaggregation algorithms (NL-DisTrad and DisNDVI) to generate time series of LST and NDVI images at fine resolution. The disaggregation algorithms aimed at generating LST and NDVI at finer scale by integrating temporal information from concurrent coarse resolution data and spatial information from a single fine resolution image. The temporal frequency of the disaggregated images is further improved by employing composite images of NDVI and LST in the spatio-temporal disaggregation method. The study further employed half-hourly incoming surface insolation and outgoing long wave radiation obtained from the Indian geostationary satellite (Kalpana-1) to convert the instantaneous ET into daily ET and subsequently to the seasonal ET, thereby improving the accuracy of ET estimates. The estimates of ET were validated with field based water balance measurements carried out in Gadana, a subbasin predominated by rice paddy fields, located in Tamil Nadu, India.

  6. Air resistance measurements on actual airplane parts

    NASA Technical Reports Server (NTRS)

    Weiselsberger, C

    1923-01-01

    For the calculation of the parasite resistance of an airplane, a knowledge of the resistance of the individual structural and accessory parts is necessary. The most reliable basis for this is given by tests with actual airplane parts at airspeeds which occur in practice. The data given here relate to the landing gear of a Siemanms-Schuckert DI airplane; the landing gear of a 'Luftfahrzeug-Gesellschaft' airplane (type Roland Dlla); landing gear of a 'Flugzeugbau Friedrichshafen' G airplane; a machine gun, and the exhaust manifold of a 269 HP engine.

  7. Do Concept Inventories Actually Measure Anything?

    ERIC Educational Resources Information Center

    Wallace, Colin S.; Bailey, Janelle M.

    2010-01-01

    Although concept inventories are among the most frequently used tools in the physics and astronomy education communities, they are rarely evaluated using item response theory (IRT). When IRT models fit the data, they offer sample-independent estimates of item and person parameters. IRT may also provide a way to measure students' learning gains…

  8. What Does the Force Concept Inventory Actually Measure?

    ERIC Educational Resources Information Center

    Huffman, Douglas; Heller, Patricia

    1995-01-01

    The Force Concept Inventory (FCI) is a 29-question, multiple-choice test designed to assess students' Newtonian and non-Newtonian conceptions of force. Presents an analysis of FCI results as one way to determine what the inventory actually measures. (LZ)

  9. Interferometric measurement of actual oblique astigmatism of ophthalmic lenses

    NASA Astrophysics Data System (ADS)

    Wihardjo, Erning

    1995-03-01

    A technique for measuring oblique astigmatism error of ophthalmic lenses is described. The technique is based on a Mach-Zehnder interferometer, which allows us to simulate the actual conditions of the eye. The effects of the lens power, the pupilary aperture size and the viewing distance in calculating a projected pupil zone on the lens are discussed. The projected pupil size on the lens affects the measurement result of the oblique astigmatism error. Conversion of the interferogram to astigmatism error in diopters is given.

  10. Characterization of personal RF electromagnetic field exposure and actual absorption for the general public.

    PubMed

    Joseph, W; Vermeeren, G; Verloock, L; Heredia, Mauricio Masache; Martens, Luc

    2008-09-01

    In this paper, personal electromagnetic field exposure of the general public due to 12 different radiofrequency sources is characterized. Twenty-eight different realistic exposure scenarios based upon time, environment, activity, and location have been defined and a relevant number of measurements were performed with a personal exposure meter. Indoor exposure in office environments can be higher than outdoor exposure: 95th percentiles of field values due to WiFi ranged from 0.36 to 0.58 V m(-1), and for DECT values of 0.33 V m(-1) were measured. The downlink signals of GSM and DCS caused the highest outdoor exposures up to 0.52 V m(-1). The highest total field exposure occurred for mobile scenarios (inside a train or bus) from uplink signals of GSM and DCS (e.g., mobile phones) due to changing environmental conditions, handovers, and higher required transmitted signals from mobile phones due to penetration through windows while moving. A method to relate the exposure to the actual whole-body absorption in the human body is proposed. An application is shown where the actual absorption in a human body model due to a GSM downlink signal is determined. Fiftieth, 95th, and 99 th percentiles of the whole-body specific absorption rate (SAR) due to this GSM signal of 0.58 microW kg(-1), 2.08 microW kg(-1), and 5.01 microW kg(-1) are obtained for a 95th percentile of 0.26 V m(-1). A practical usable function is proposed for the relation between the whole-body SAR and the electric fields. The methodology of this paper enables epidemiological studies to make an analysis in combination with both electric field and actual whole-body SAR values and to compare exposure with basic restrictions. PMID:18695413

  11. Comprehensive Evaluation of Attitude and Orbit Estimation Using Actual Earth Magnetic Field Data

    NASA Technical Reports Server (NTRS)

    Deutschmann, Julie K.; Bar-Itzhack, Itzhack Y.

    2000-01-01

    A single, augmented Extended Kalman Filter (EKF), which simultaneously and autonomously estimates spacecraft attitude and orbit has been developed and successfully tested with real magnetometer and gyro data only. Because the earth magnetic field is a function of time and position, and because time is known quite precisely, the differences between the computed and measured magnetic field components, as measured by the magnetometers throughout the entire spacecraft orbit, are a function of both orbit and attitude errors. Thus, conceivably these differences could be used to estimate both orbit and attitude; an observability study validated this assumption. The results of testing the EKF with actual magnetometer and gyro data, from four satellites supported by the NASA Goddard Space Flight Center (GSFC) Guidance, Navigation, and Control Center, are presented and evaluated. They confirm the assumption that a single EKF can estimate both attitude and orbit when using gyros and magnetometers only.

  12. Construction and Validation of a Scale to Measure Maslow's Concept of Self-Actualization

    ERIC Educational Resources Information Center

    Jones, Kenneth Melvin; Randolph, Daniel Lee

    1978-01-01

    Designed to measure self-actualization as defined by Abraham Maslow, the Jones Self Actualizing Scale, as assessed in this study, possesses content validity, reliability, and a number of other positive characteristics. (JC)

  13. Actual Minds of Two Halves: Measurement, Metaphor and the Message

    ERIC Educational Resources Information Center

    Stewart, Georgina

    2015-01-01

    This article takes "measurement" as a will to determine or fix space and time, which allows for a comparison of ontological models of space and time from Western and Maori traditions. The spirit of "measurement" is concomitantly one of fixing meaning, which is suggested as the essence of the growth of the scientific genre of…

  14. Thermal Performance of Cryogenic Piping Multilayer Insulation in Actual Field Installations

    NASA Technical Reports Server (NTRS)

    Fesmire, J.; Augustnynowicz, S.; Thompson, K. (Technical Monitor)

    2002-01-01

    A standardized way of comparing the thermal performance of different pipelines in different sizes is needed. Vendor data for vacuum-insulated piping are typically given in heat leak rate per unit length (W/m) for a specific diameter pipeline. An overall k-value for actual field installations (k(sub oafi)) is therefore proposed as a more generalized measure for thermal performance comparison and design calculation. The k(sub oafi) provides a direct correspondence to the k-values reported for insulation materials and illustrates the large difference between ideal multilayer insulation (MLI) and actual MLI performance. In this experimental research study, a section of insulated piping was tested under cryogenic vacuum conditions, including simulated spacers and bending. Several different insulation systems were tested using a 1-meter-long cylindrical cryostat test apparatus. The simulated spacers tests showed significant degradation in the thermal performance of a given insulation system. An 18-meter-long pipeline test apparatus is now in operation at the Cryogenics Test Laboratory, NASA Kennedy Space Center, for conducting liquid nitrogen thermal performance tests.

  15. Undulator Field Integral Measurements

    SciTech Connect

    Wolf, Zachary

    2010-12-07

    The LCLS undulator field integrals must be very small so that the beam trajectory slope and offset stay within tolerance. In order to make accurate measurements of the small field integrals, a long coil will be used. This note describes the design of the coil measurement system.

  16. Magnetic Field Measurement System

    SciTech Connect

    Kulesza, Joe; Johnson, Eric; Lyndaker, Aaron; Deyhim, Alex; Waterman, Dave; Blomqvist, K. Ingvar; Dunn, Jonathan Hunter

    2007-01-19

    A magnetic field measurement system was designed, built and installed at MAX Lab, Sweden for the purpose of characterizing the magnetic field produced by Insertion Devices (see Figure 1). The measurement system consists of a large granite beam roughly 2 feet square and 14 feet long that has been polished beyond laboratory grade for flatness and straightness. The granite precision coupled with the design of the carriage yielded minimum position deviations as measured at the probe tip. The Hall probe data collection and compensation technique allows exceptional resolution and range while taking data on the fly to programmable sample spacing. Additional flip coil provides field integral data.

  17. Field measurement of ventilation rates.

    PubMed

    Persily, A K

    2016-02-01

    Ventilation rates have significant impacts on building energy use and indoor contaminant concentrations, making them key parameters in building performance. Ventilation rates have been measured in buildings for many decades, and there are mature measurement approaches available to researchers and others who need to know actual ventilation rates in buildings. Despite the fact that ventilation rates are critical in interpreting indoor concentration measurements, it is disconcerting how few Indoor Air Quality field studies measure ventilation rates or otherwise characterize the ventilation design of the study building(s). This paper summarizes parameters of interest in characterizing building ventilation, available methods for quantifying these parameters, and challenges in applying these methods to different types of buildings and ventilation systems. These parameters include whole-building air change rates, system outdoor air intake rates, and building infiltration rates. Tracer gas methods are reviewed as well as system airflow rate measurements using, for example, duct traverses. Several field studies of ventilation rates conducted over the past 75 years are described to highlight the approaches employed and the findings obtained. PMID:25689218

  18. Measuring the Disparities between Biology Undergraduates' Perceptions and Their Actual Knowledge of Scientific Literature with Clickers

    ERIC Educational Resources Information Center

    Bandyopadhyay, Aditi

    2013-01-01

    This article demonstrates an innovative method used to determine the need for information literacy among science undergraduate students at Adelphi University. Using clickers technology, this study measured the disconnect between biology undergraduates' perceived and actual knowledge of scientific literature. The quantitative data collected in the…

  19. Relative Proximity Theory: Measuring the Gap between Actual and Ideal Online Course Delivery

    ERIC Educational Resources Information Center

    Swart, William; MacLeod, Kenneth; Paul, Ravi; Zhang, Aixiu; Gagulic, Mario

    2014-01-01

    Based on the Theory of Transactional Distance and Needs Assessment, this article reports a procedure for quantitatively measuring how close the actual delivery of a course was to ideal, as perceived by students. It extends Zhang's instrument and prescribes the computational steps to calculate relative proximity at the element and construct…

  20. Heavy rain field measurements

    NASA Technical Reports Server (NTRS)

    Melson, ED

    1991-01-01

    A weight-measuring rain gauge was developed to collect rain data and configured to operate at a high sample rate (one sample pre second). Instead of averaging the rain rate in minutes, hours, and sometime days as normally performed, the rain data collected are examined in seconds. The results of six field sites are compiled. Rain rate levels, duration of downpours, and frequency of heavy rainfall events are presented.

  1. Field test of the Cognitive Interview: enhancing the recollection of actual victims and witnesses of crime.

    PubMed

    Fisher, R P; Geiselman, R E; Amador, M

    1989-10-01

    The Cognitive Interview was tested in the field to enhance the recollection of actual victims and witnesses of crime. The technique is based on laboratory-tested principles of memory retrieval, knowledge representation, and communication. Seven experienced detectives from the Metro-Dade Police Department were trained to use the technique and were compared with 9 untrained detectives. Before and after training, all detectives tape-recorded interviews with victims and witnesses of crime. The trained detectives elicited 47% more information after than before training, and 63% more information than did the untrained detectives. Overall collaboration rates (94%) were extremely high and were equivalent for pre- and posttrained interviews. Because the Cognitive Interview reliably enhances memory and is easily learned and administered, it should be useful for a variety of investigative interviews. PMID:2793772

  2. Measurement of radiofrequency fields

    NASA Astrophysics Data System (ADS)

    Leonowich, J. A.

    1992-05-01

    We are literally surrounded by radiofrequency (RFR) and microwave radiation, from both natural and man-made sources. The identification and control of man-made sources of RFR has become a high priority of radiation safety professionals in recent years. For the purposes of this paper, we will consider RFR to cover the frequencies from 3 kHz to 300 MHz, and microwaves from 300 MHz to 300 GHz, and will use the term RFR interchangeably to describe both. Electromagnetic radiation below 3 kHz is considered Extremely Low Frequency (ELF) and will not be discussed in this paper. Unlike x- and gamma radiation, RFR is non-ionizing. The energy of any RFR photon is insufficient to produce ionizations in matter. The measurement and control of RFR hazards is therefore fundamentally different from ionizing radiation. The purpose of this paper is to acquaint the reader with the fundamental issues involved in measuring and safely using RFR fields.

  3. Measurement of radiofrequency fields

    SciTech Connect

    Leonowich, J.A.

    1992-05-01

    We are literally surrounded by radiofrequency (RFR) and microwave radiation, from both natural and man-made sources. The identification and control of man-made sources of RFR has become a high priority of radiation safety professionals in recent years. For the purposes of this paper, we will consider RFR to cover the frequencies from 3 kHz to 300 MHz, and microwaves from 300 MHz to 300 GHz, and will use the term RFR interchangeably to describe both. Electromagnetic radiation and field below 3 kHz is considered Extremely Low Frequency (ELF) and will not be discussed in this paper. Unlike x- and gamma radiation, RFR is non-ionizing. The energy of any RFR photon is insufficient to produce ionizations in matter. The measurement and control of RFR hazards is therefore fundamentally different from ionizing radiation. The purpose of this paper is to acquaint the reader with the fundamental issues involved in measuring and safely using RFR fields. 23 refs.

  4. Passive field reflectance measurements

    NASA Astrophysics Data System (ADS)

    Weber, Christian; Schinca, Daniel C.; Tocho, Jorge O.; Videla, Fabian

    2008-10-01

    The results of reflectance measurements performed with a three-band passive radiometer with independent channels for solar irradiance reference are presented. Comparative operation between the traditional method that uses downward-looking field and reference white panel measurements and the new approach involving duplicated downward- and upward-looking spectral channels (each latter one with its own diffuser) is analyzed. The results indicate that the latter method performs in very good agreement with the standard method and is more suitable for passive sensors under rapidly changing atmospheric conditions (such as clouds, dust, mist, smog and other scatterers), since a more reliable synchronous recording of reference and incident light is achieved. Besides, having separate channels for the reference and the signal allows a better balancing of gains in the amplifiers for each spectral channel. We show the results obtained in the determination of the normalized difference vegetation index (NDVI) corresponding to the period 2004-2007 field experiments concerning weed detection in soybean stubbles and fertilizer level assessment in wheat. The method may be used to refine sensor-based nitrogen fertilizer rate recommendations and to determine suitable zones for herbicide applications.

  5. Experimental evaluation of actual delivered dose using mega-voltage cone-beam CT and direct point dose measurement

    SciTech Connect

    Matsubara, Kana; Kohno, Ryosuke; Nishioka, Shie; Shibuya, Toshiyuki; Ariji, Takaki; Akimoto, Tetsuo; Saitoh, Hidetoshi

    2013-07-01

    Radiation therapy in patients is planned by using computed tomography (CT) images acquired before start of the treatment course. Here, tumor shrinkage or weight loss or both, which are common during the treatment course for patients with head-and-neck (H and N) cancer, causes unexpected differences from the plan, as well as dose uncertainty with the daily positional error of patients. For accurate clinical evaluation, it is essential to identify these anatomical changes and daily positional errors, as well as consequent dosimetric changes. To evaluate the actual delivered dose, the authors proposed direct dose measurement and dose calculation with mega-voltage cone-beam CT (MVCBCT). The purpose of the present study was to experimentally evaluate dose calculation by MVCBCT. Furthermore, actual delivered dose was evaluated directly with accurate phantom setup. Because MVCBCT has CT-number variation, even when the analyzed object has a uniform density, a specific and simple CT-number correction method was developed and applied for the H and N site of a RANDO phantom. Dose distributions were calculated with the corrected MVCBCT images of a cylindrical polymethyl methacrylate phantom. Treatment processes from planning to beam delivery were performed for the H and N site of the RANDO phantom. The image-guided radiation therapy procedure was utilized for the phantom setup to improve measurement reliability. The calculated dose in the RANDO phantom was compared to the measured dose obtained by metal-oxide-semiconductor field-effect transistor detectors. In the polymethyl methacrylate phantom, the calculated and measured doses agreed within about +3%. In the RANDO phantom, the dose difference was less than +5%. The calculated dose based on simulation-CT agreed with the measured dose within±3%, even in the region with a high dose gradient. The actual delivered dose was successfully determined by dose calculation with MVCBCT, and the point dose measurement with the image

  6. Direct and Indirect Measures of Learning Outcomes in an MSW Program: What Do We Actually Measure?

    ERIC Educational Resources Information Center

    Calderon, Orly

    2013-01-01

    This study offers a unique perspective on assessment of learning by comparing results from direct and indirect measures in a social work graduate program across two campuses of a single university. The findings suggest that students' perceptions of learning are not necessarily reflective of content and applied skills mastery. Perception of…

  7. Personality Trait Differences Between Young and Middle-Aged Adults: Measurement Artifacts or Actual Trends?

    PubMed

    Nye, Christopher D; Allemand, Mathias; Gosling, Samuel D; Potter, Jeff; Roberts, Brent W

    2016-08-01

    A growing body of research demonstrates that older individuals tend to score differently on personality measures than younger adults. However, recent research using item response theory (IRT) has questioned these findings, suggesting that apparent age differences in personality traits merely reflect artifacts of the response process rather than true differences in the latent constructs. Conversely, other studies have found the opposite-age differences appear to be true differences rather than response artifacts. Given these contradictory findings, the goal of the present study was to examine the measurement equivalence of personality ratings drawn from large groups of young and middle-aged adults (a) to examine whether age differences in personality traits could be completely explained by measurement nonequivalence and (b) to illustrate the comparability of IRT and confirmatory factor analysis approaches to testing equivalence in this context. Self-ratings of personality traits were analyzed in two groups of Internet respondents aged 20 and 50 (n = 15,726 in each age group). Measurement nonequivalence across these groups was negligible. The effect sizes of the mean differences due to nonequivalence ranged from -.16 to .15. Results indicate that personality trait differences across age groups reflect actual differences rather than merely response artifacts. PMID:25773456

  8. Positioning the actual interference fringe pattern on the tooth flank in measuring gear tooth flanks by laser interferometry

    NASA Astrophysics Data System (ADS)

    Fang, Suping; Wang, Leijie; Liu, Shiqiao; Komori, Masaharu; Kubo, Aizoh

    2011-05-01

    In measuring form deviation of gear tooth flanks by laser interferometry, the collected interference fringe pattern (IFP) is badly distorted, in the case of shape, relative to the actual tooth flank. Meanwhile, a clear and definite mapping relationship between the collected IFP and the actual tooth flank is indispensable for both transforming phase differences into deviation values and positioning the measurement result on the actual tooth flank. In order to solve these problems, this paper proposes a method using the simulation tooth image as a bridge connecting the actual tooth flank and the collected IFP. The mapping relationship between the simulation tooth image and the actual tooth flank has been obtained by ray tracing methods [Fang et al., Appl. Opt. 49(33), 6409-6415 (2010)]. This paper mainly discusses how to build the relationship between the simulation tooth image and the collected IFP by using a matching algorithm of two characteristic point sets. With the combination of the two above-mentioned assistant mapping relationships, the mapping relationship between the collected IFP and the actual tooth flank can be built; the collected IFP can be positioned on the actual tooth flank. Finally, the proposed method is employed in a measurement of the form deviation of a gear tooth flank and the result proves the feasibility of the proposed method.

  9. Testing data evaluation strategies for estimating precipitation and actual evaporation from precision lysimeter measurements

    NASA Astrophysics Data System (ADS)

    Schrader, Frederik; Durner, Wolfgang; Fank, Johann; Pütz, Thomas; Wollschläger, Ute

    2014-05-01

    Weighing lysimeters have long been recognized as valuable tools not only for monitoring of groundwater recharge and solute transport, but also for the determination of the soil water balance and quantification of water exchange processes at the soil-plant-atmosphere interface. If well embedded into an equally-vegetated environment, they reach a hitherto unprecedented accuracy in estimating precipitation (P) by rain, dew, fog, rime and snow, as well as actual evapotranspiration (ET). At the same time, they largely avoid errors made by traditional micrometeorological instruments, such as the wind error of Hellman rain samplers or the influence of subsurface heterogeneity on readings from in situ instrumentation of soil water state variables. Beginning in 2008, the Helmholtz Association established a network of terrestrial environmental observatories (TERENO) that aim at long-term monitoring of climate and land-use change consequences. A total of 126 identically designed large weighing lysimeters, operating at a sampling frequency of 1 min-1, were installed for this purpose, which raises the demand for standardized data processing methods. In theory, estimating P and ET from these measurements is straightforward: An increase in the combined mass of the soil monolith and the collected seepage water indicates P, while a decrease indicates ET. However, in practice, lysimeter data are prone to numerous sources of error, including, but not limited to, outliers, systematic errors due to plant growth and removal, data gaps, and stochastic fluctuations. The latter pose a particularly challenging problem - if we would directly calculate P and ET from a time-series that is affected by random noise, every positive fluctuation would be interpreted as P and every negative one as ET. Consequently, we would overestimate both quantities by far. The aim of this study was to evaluate algorithms that focus on eliminating the effect of these fluctuations and to estimate actual fluxes

  10. Indicated and actual mass inventory measurements for an inverted U-tube steam generator

    SciTech Connect

    Loomis, G.G.; Plessinger, M.P.; Boucher, T.J.

    1986-01-01

    Results from an experimental investigation of actual versus indicated secondary liquid level in a steam generator at steaming conditions are presented. The experimental investigation was performed in two different small scale U-tube-in-shell steam generators at typical pressurized water reactor operating conditions (5-7 MPa; saturated) in the Semiscale facility. During steaming conditions, the indicated secondary liquid level was found to vary considerably from the actual ''bottled-up'' liquid level. These difference between indicated and actual liquid level are related to the frictional pressure drop associated with the two-phase steaming condition in the riser. Data from a series of bottle-up experiments (Simultaneously, the primary heat source and secondary feed and steam are terminated) are tabulated and the actual liquid level is correlated to the indicated liquid level.

  11. Actual evapotranspiration and precipitation measured by lysimeters: a comparison with eddy covariance and tipping bucket

    NASA Astrophysics Data System (ADS)

    Gebler, S.; Hendricks Franssen, H.-J.; Pütz, T.; Post, H.; Schmidt, M.; Vereecken, H.

    2015-05-01

    This study compares actual evapotranspiration (ETa) measurements by a set of six weighable lysimeters, ETa estimates obtained with the eddy covariance (EC) method, and evapotranspiration calculated with the full-form Penman-Monteith equation (ETPM) for the Rollesbroich site in the Eifel (western Germany). The comparison of ETa measured by EC (including correction of the energy balance deficit) and by lysimeters is rarely reported in the literature and allows more insight into the performance of both methods. An evaluation of ETa for the two methods for the year 2012 shows a good agreement with a total difference of 3.8% (19 mm) between the ETa estimates. The highest agreement and smallest relative differences (< 8%) on a monthly basis between both methods are found in summer. ETa was close to ETPM, indicating that ET was energy limited and not limited by water availability. ETa differences between lysimeter and EC were mainly related to differences in grass height caused by harvest and the EC footprint. The lysimeter data were also used to estimate precipitation amounts in combination with a filter algorithm for the high-precision lysimeters recently introduced by Peters et al. (2014). The estimated precipitation amounts from the lysimeter data differ significantly from precipitation amounts recorded with a standard rain gauge at the Rollesbroich test site. For the complete year 2012 the lysimeter records show a 16 % higher precipitation amount than the tipping bucket. After a correction of the tipping bucket measurements by the method of Richter (1995) this amount was reduced to 3%. With the help of an on-site camera the precipitation measurements of the lysimeters were analyzed in more detail. It was found that the lysimeters record more precipitation than the tipping bucket, in part related to the detection of rime and dew, which contribute 17% to the yearly difference between both methods. In addition, fog and drizzle explain an additional 5.5% of the total

  12. Measuring Earth's Magnetic Field Simply.

    ERIC Educational Resources Information Center

    Stewart, Gay B.

    2000-01-01

    Describes a method for measuring the earth's magnetic field using an empty toilet paper tube, copper wire, clear tape, a battery, a linear variable resistor, a small compass, cardboard, a protractor, and an ammeter. (WRM)

  13. Bowen ratio measurements above various vegetation covers and its comparison with actual evapotranspiration estimated by SoilClim model

    NASA Astrophysics Data System (ADS)

    Hlavinka, P.; Trnka, M.; Fischer, M.; Kucera, J.; Mozny, M.; Zalud, Z.

    2010-09-01

    The principle of Bowen ratio is one of the available techniques for measurements of actual evapotranspiration (ETa) as one of essential water balance fractions. The main aims of submitted study were: (i) to compare the water balance of selected crops, (ii) to compare outputs of SoilClim model with observed parameters (including ETa on Bowen ratio basis). The measurements were conducted at two experimental stations in the Czech Republic (Polkovice 49°23´ (N), 17°17´ (E), 205 m a.s.l.; Domanínek 49°32´ (N), 16°15´ (E), 544 m a.s.l.) during the years 2009 and 2010. Together with Bowen ratio the global solar radiation, radiation balance, soil heat flux, volumetric soil moisture and temperature within selected depths, precipitation and wind speed were measured. The measurements were conducted simultaneously above various covers within the same soil conditions: spring barley vs. winter wheat, spring barley vs. winter rape; grass vs. poplars; harvested field after tillage vs. harvested field after cereals without any tillage. The observed parameters from different covers were compared with SoilClim estimates. SoilClim model is modular software for water balance and soil temperature modelling and finally could be used for soil Hydric and Thermic regimes (according to USDA classification) identification. The core of SoilClim is based on modified FAO Penman-Monteith methodology. Submitted study proved the applicability of SoilClim model for ETa, soil moisture within two defined layers and soil temperature (in 0.5 m depth) estimates for various crops, covers, selected soil types and climatic conditions. Acknowledgement: We gratefully acknowledge the support of the Grant Agency of the Czech Republic (no. 521/09/P479) and the project NAZV QI91C054. The study was also supported by Research plan No. MSM6215648905 "Biological and technological aspects of sustainability of controlled ecosystems and their adaptability to climate change".

  14. Actual evapotranspiration and precipitation measured by lysimeters: a comparison with eddy covariance and tipping bucket

    NASA Astrophysics Data System (ADS)

    Gebler, S.; Hendricks Franssen, H.-J.; Pütz, T.; Post, H.; Schmidt, M.; Vereecken, H.

    2014-12-01

    This study compares actual evapotranspiration (ETa) measurements by a set of six weighable lysimeters, ETa estimates obtained with the eddy covariance (EC) method, and potential crop evapotranspiration according to FAO (ETc-FAO) for the Rollesbroich site in the Eifel (Western Germany). The comparison of ETa measured by EC (including correction of the energy balance deficit) and by lysimeters is rarely reported in literature and allows more insight into the performance of both methods. An evaluation of ETa for the two methods for the year 2012 shows a good agreement with a total difference of 3.8% (19 mm) between the ETa estimates. The highest agreement and smallest relative differences (<8%) on monthly basis between both methods are found in summer. ETa was close to ETc-FAO, indicating that ET was energy limited and not limited by water availability. ETa differences between lysimeter, ETc-FAO, and EC were mainly related to differences in grass height caused by harvesting management and the EC footprint. The lysimeter data were also used to estimate precipitation amounts in combination with a filter algorithm for high precision lysimeters recently introduced by Peters et al. (2014). The estimated precipitation amounts from the lysimeter data show significant differences compared to the precipitation amounts recorded with a standard rain gauge at the Rollesbroich test site. For the complete year 2012 the lysimeter records show a 16% higher precipitation amount than the tipping bucket. With the help of an on-site camera the precipitation measurements of the lysimeters were analyzed in more detail. It was found that the lysimeters record more precipitation than the tipping bucket in part related to the detection of rime and dew, which contributes 17% to the yearly difference between both methods. In addition, fog and drizzle explain an additional 5.5% of the total difference. Larger differences are also recorded for snow and sleet situations. During snowfall, the

  15. Measurements of magnetic field alignment

    SciTech Connect

    Kuchnir, M.; Schmidt, E.E.

    1987-11-06

    The procedure for installing Superconducting Super Collider (SSC) dipoles in their respective cryostats involves aligning the average direction of their field with the vertical to an accuracy of 0.5 mrad. The equipment developed for carrying on these measurements is described and the measurements performed on the first few prototypes SSC magnets are presented. The field angle as a function of position in these 16.6 m long magnets is a characteristic of the individual magnet with possible feedback information to its manufacturing procedure. A comparison of this vertical alignment characteristic with a magnetic field intensity (by NMR) characteristic for one of the prototypes is also presented. 5 refs., 7 figs.

  16. Development and Validation of Short Forms of Some Instruments Measuring Student Perceptions of Actual and Preferred Classroom Learning Environment.

    ERIC Educational Resources Information Center

    Fraser, Barry J.; Fisher, Darrell L.

    1983-01-01

    Describes development/validation of short forms of Individualized Classroom Environment Questionnaire (ICEQ), My Class Inventory (MCI), and Classroom Environment Scale (CES). In addition to these forms measuring perceptions of actual classroom environment, ICEQ and CES short forms measuring preferred classroom environment were also developed.…

  17. Optical measurements of gravity fields

    NASA Technical Reports Server (NTRS)

    Maleki, L.; Yu, N.; Matsko, A.

    2003-01-01

    Optical measurements of a gravitational field with sensitivity close to the sensitivity of atomic devices are possible if one detects properties of light after its interaction with optically thick atomic cloud moving freely in the gravity field. A nondestructive detection of a number of ultracold atoms in a cloud as well as tracking of the ground state population distribution of the atoms is possible by optical means.

  18. Measurement of surface velocity fields

    NASA Technical Reports Server (NTRS)

    Mann, J. A., Jr.

    1979-01-01

    A new technique for measuring surface velocity fields is briefly described. It determines the surface velocity vector as a function of location and time by the analysis of thermal fluctuations of the surface profile in a small domain around the point of interest. The apparatus now being constructed will be used in a series of experiments involving flow fields established by temperature gradients imposed along a surface.

  19. Electric and magnetic field measurements

    NASA Astrophysics Data System (ADS)

    McKnight, R. H.; Kotter, F. R.; Misakian, M.; Ortiz, P.

    1981-02-01

    The NBS program concerned with developing methods for evaluating and calibrating instrumentation for use in measuring the electric field and various ion-related electrical quantities in the vicinity of high-voltage direct current (HVDC) transmission lines is described. Apparatus designed to simulate the transmission line environment is also considered.

  20. Electric and magnetic field measurements

    NASA Astrophysics Data System (ADS)

    McKnight, R. H.; Kotter, F. R.; Misakian, M.; Hagler, J. N.

    1982-07-01

    Methods for evaluating and calibrating instrumentation for use in measuring the electric field and various ion related electrical quantities in the vicinity of high voltage direct current transmission lines are developed. Apparatus designed to simulate the transmission line environment are also evaluated.

  1. Surface energy balance and actual evapotranspiration of the transboundary Indus Basin estimated from satellite measurements and the ETLook model

    NASA Astrophysics Data System (ADS)

    Bastiaanssen, W. G. M.; Cheema, M. J. M.; Immerzeel, W. W.; Miltenburg, I. J.; Pelgrum, H.

    2012-11-01

    The surface energy fluxes and related evapotranspiration processes across the Indus Basin were estimated for the hydrological year 2007 using satellite measurements. The new ETLook remote sensing model (version 1) infers information on actual Evaporation (E) and actual Transpiration (T) from combined optical and passive microwave sensors, which can observe the land-surface even under persistent overcast conditions. A two-layer Penman-Monteith equation was applied for quantifying soil and canopy evaporation. The novelty of the paper is the computation of E and T across a vast area (116.2 million ha) by using public domain microwave data that can be applied under all weather conditions, and for which no advanced input data are required. The average net radiation for the basin was estimated as being 112 Wm-2. The basin average sensible, latent and soil heat fluxes were estimated to be 80, 32, and 0 Wm-2, respectively. The average evapotranspiration (ET) and evaporative fraction were 1.2 mm d-1 and 0.28, respectively. The basin wide ET was 496 ± 16.8 km3 yr-1. Monte Carlo analysis have indicated 3.4% error at 95% confidence interval for a dominant land use class. Results compared well with previously conducted soil moisture, lysimeter and Bowen ratio measurements at field scale (R2 = 0.70; RMSE = 0.45 mm d-1; RE = -11.5% for annual ET). ET results were also compared against earlier remote sensing and modeling studies for various regions and provinces in Pakistan (R2 = 0.76; RMSE = 0.29 mmd-1; RE = 6.5% for annual ET). The water balance for all irrigated areas together as one total system in Pakistan and India (26.02 million ha) show a total ET value that is congruent with the ET value from the ETLook surface energy balance computations. An unpublished validation of the same ETLook model for 23 jurisdictional areas covering the entire Australian continent showed satisfactory results given the quality of the watershed data and the diverging physiographic and climatic

  2. Role of Ratings of Perceived Exertion during Self-Paced Exercise: What are We Actually Measuring?

    PubMed

    Abbiss, Chris R; Peiffer, Jeremiah J; Meeusen, Romain; Skorski, Sabrina

    2015-09-01

    Ratings of perceived exertion (RPE) and effort are considered extremely important in the regulation of intensity during self-paced physical activity. While effort and exertion are slightly different constructs, these terms are often used interchangeably within the literature. The development of perceptions of both effort and exertion is a complicated process involving numerous neural processes occurring in various regions within the brain. It is widely accepted that perceptions of effort are highly dependent on efferent copies of central drive which are sent from motor to sensory regions of the brain. Additionally, it has been suggested that perceptions of effort and exertion are integrated based on the balance between corollary discharge and actual afferent feedback; however, the involvement of peripheral afferent sensory feedback in the development of such perceptions has been debated. As such, this review examines the possible difference between effort and exertion, and the implications of such differences in understanding the role of such perceptions in the regulation of pace during exercise. PMID:26054383

  3. Comparison between predicted and actual accuracies for an Ultra-Precision CNC measuring machine

    SciTech Connect

    Thompson, D.C.; Fix, B.L.

    1995-05-30

    At the 1989 CIRP annual meeting, we reported on the design of a specialized, ultra-precision CNC measuring machine, and on the error budget that was developed to guide the design process. In our paper we proposed a combinatorial rule for merging estimated and/or calculated values for all known sources of error, to yield a single overall predicted accuracy for the machine. In this paper we compare our original predictions with measured performance of the completed instrument.

  4. A user-study measuring the effects of lexical simplification and coherence enhancement on perceived and actual text difficulty

    PubMed Central

    Leroy, Gondy; Kauchak, David; Mouradi, Obay

    2013-01-01

    Purpose Low patient health literacy has been associated with cost increases in medicine because it contributes to inadequate care. Providing explanatory text is a convenient approach to distribute medical information and increase health literacy. Unfortunately, writing text that is easily understood is challenging. This work tests two text features for their impact on understanding: lexical simplification and coherence enhancement. Methods A user study was conducted to test the features’ effect on perceived and actual text difficulty. Individual sentences were used to test perceived difficulty. Using a 5-point Likert scale, participants compared eight pairs of original and simplified sentences. Abstracts were used to test actual difficulty. For each abstract, four versions were created: original, lexically simplified, coherence enhanced, and lexically simplified and coherence enhanced. Using a mixed design, one group of participants worked with the original and lexically simplified documents (no coherence enhancement) while a second group worked with the coherence enhanced versions. Actual difficulty was measured using a Cloze measure and multiple-choice questions. Results Using Amazon’s Mechanical Turk, 200 people participated of which 187 qualified based on our data qualification tests. A paired-samples t-test for the sentence ratings showed a significant reduction in difficulty after lexical simplification (p < .001). Results for actual difficulty are based on the abstracts and associated tasks. A two-way ANOVA for the Cloze test showed no effect of coherence enhancement but a main effect for lexical simplification, with the simplification leading to worse scores (p = .004). A follow-up ANOVA showed this effect exists only for function words when coherence was not enhanced (p = .008). In contrast, a two-way ANOVA for answering multiple-choice questions showed a significant beneficial effect of coherence enhancement (p = .003) but no effect of lexical

  5. Intended release and actual retention of alfalfa leafcutting bees (Hymenoptera: Megachilidae) for pollination in commercial alfalfa seed fields.

    PubMed

    Pitts-Singer, Theresa L

    2013-04-01

    Low, medium, and high stocking densities (15,000; 30,000; and 45,000-50,000 bees per acre, respectively) of Megachile rotundata (F.) (Hymenoptera: Megachilidae), the alfalfa leafcutting bee, were released over 4 yr in three research plots of Utah alfalfa, Medicago sativa L. (Fabaceae), planted at seed-production rates. A low percentage of bees (46-79% of released) survived the incubation and field-emergence processes; of those bees, the number of females that established at the nesting sites was 25-100%. Of the three field sites, one site consistently retained more females and produced more completed nests than the other sites, all of which usually had poor female establishment and progeny production. In addition, floral resources were depleted over time, but many flowers remained unvisited over the season. Nest production decreased over time, as numbers of flowers and female bees declined. Significant positive relationships were found between the intended stocking densities and 1) the number of females that actually survived incubation and field emergence and 2) the number of females that established nests. The number of females that established nests was positively affected by the number of females that survived to emerge in the field. The percentage of females that established was not significantly affected by the intended number of released bees, countering a prediction that the release of fewer bees would allow more females to establish nests and achieve high reproductive success. For growers, it may be more frugal to use modest numbers of M. rotundata for pollination, because many of the bees at medium and high stocking densities do not nest in grower-provided bee boards. PMID:23786042

  6. Designed microtremor array based actual measurement and analysis of strong ground motion at Palu city, Indonesia

    NASA Astrophysics Data System (ADS)

    Thein, Pyi Soe; Pramumijoyo, Subagyo; Brotopuspito, Kirbani Sri; Wilopo, Wahyu; Kiyono, Junji; Setianto, Agung; Putra, Rusnardi Rahmat

    2015-04-01

    In this study, we investigated the strong ground motion characteristics under Palu City, Indonesia. The shear wave velocity structures evaluated by eight microtremors measurement are the most applicable to determine the thickness of sediments and average shear wave velocity with Vs ≤ 300 m/s. Based on subsurface underground structure models identified, earthquake ground motion was estimated in the future Palu-Koro earthquake by using statistical green's function method. The seismic microzonation parameters were carried out by considering several significant controlling factors on ground response at January 23, 2005 earthquake.

  7. Designed microtremor array based actual measurement and analysis of strong ground motion at Palu city, Indonesia

    SciTech Connect

    Thein, Pyi Soe; Pramumijoyo, Subagyo; Wilopo, Wahyu; Setianto, Agung; Brotopuspito, Kirbani Sri; Kiyono, Junji; Putra, Rusnardi Rahmat

    2015-04-24

    In this study, we investigated the strong ground motion characteristics under Palu City, Indonesia. The shear wave velocity structures evaluated by eight microtremors measurement are the most applicable to determine the thickness of sediments and average shear wave velocity with Vs ≤ 300 m/s. Based on subsurface underground structure models identified, earthquake ground motion was estimated in the future Palu-Koro earthquake by using statistical green’s function method. The seismic microzonation parameters were carried out by considering several significant controlling factors on ground response at January 23, 2005 earthquake.

  8. What Do Contrast Threshold Equivalent Noise Studies Actually Measure? Noise vs. Nonlinearity in Different Masking Paradigms

    PubMed Central

    Baldwin, Alex S.; Baker, Daniel H.; Hess, Robert F.

    2016-01-01

    The internal noise present in a linear system can be quantified by the equivalent noise method. By measuring the effect that applying external noise to the system’s input has on its output one can estimate the variance of this internal noise. By applying this simple “linear amplifier” model to the human visual system, one can entirely explain an observer’s detection performance by a combination of the internal noise variance and their efficiency relative to an ideal observer. Studies using this method rely on two crucial factors: firstly that the external noise in their stimuli behaves like the visual system’s internal noise in the dimension of interest, and secondly that the assumptions underlying their model are correct (e.g. linearity). Here we explore the effects of these two factors while applying the equivalent noise method to investigate the contrast sensitivity function (CSF). We compare the results at 0.5 and 6 c/deg from the equivalent noise method against those we would expect based on pedestal masking data collected from the same observers. We find that the loss of sensitivity with increasing spatial frequency results from changes in the saturation constant of the gain control nonlinearity, and that this only masquerades as a change in internal noise under the equivalent noise method. Part of the effect we find can be attributed to the optical transfer function of the eye. The remainder can be explained by either changes in effective input gain, divisive suppression, or a combination of the two. Given these effects the efficiency of our observers approaches the ideal level. We show the importance of considering these factors in equivalent noise studies. PMID:26953796

  9. What is actually measured in process evaluations for worksite health promotion programs: a systematic review

    PubMed Central

    2013-01-01

    of the process evaluations is mostly poor to average, resulting in a lack of systematically measured barriers/facilitators. The narrow focus on implementation makes it difficult to explore the relationship between effectiveness and implementation. Furthermore, the operationalisation of process components varied between studies, indicating a need for consensus about defining and operationalising process components. PMID:24341605

  10. Rotating Capacitor Measures Steady Electric Fields

    NASA Technical Reports Server (NTRS)

    Johnston, A. R.; Kirkham, H.; Eng, B.

    1986-01-01

    Portable sensor measures electric fields created by dc powerlines or other dc-high-voltage sources. Measures fields from 70 to 50,000 V/m with linearity of 2 percent. Sensor used at any height above ground. Measures both magnitude and direction of field and provides signals representing these measurements to remote readout device. Sensor functions with minimal disturbance of field it is measuring.

  11. A Coupled Remote Sensing and Simplified Surface Energy Balance Approach to Estimate Actual Evapotranspiration from Irrigated Fields

    PubMed Central

    Senay, Gabriel B.; Budde, Michael; Verdin, James P.; Melesse, Assefa M.

    2007-01-01

    Accurate crop performance monitoring and production estimation are critical for timely assessment of the food balance of several countries in the world. Since 2001, the Famine Early Warning Systems Network (FEWS NET) has been monitoring crop performance and relative production using satellite-derived data and simulation models in Africa, Central America, and Afghanistan where ground-based monitoring is limited because of a scarcity of weather stations. The commonly used crop monitoring models are based on a crop water-balance algorithm with inputs from satellite-derived rainfall estimates. These models are useful to monitor rainfed agriculture, but they are ineffective for irrigated areas. This study focused on Afghanistan, where over 80 percent of agricultural production comes from irrigated lands. We developed and implemented a Simplified Surface Energy Balance (SSEB) model to monitor and assess the performance of irrigated agriculture in Afghanistan using a combination of 1-km thermal data and 250-m Normalized Difference Vegetation Index (NDVI) data, both from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. We estimated seasonal actual evapotranspiration (ETa) over a period of six years (2000-2005) for two major irrigated river basins in Afghanistan, the Kabul and the Helmand, by analyzing up to 19 cloud-free thermal and NDVI images from each year. These seasonal ETa estimates were used as relative indicators of year-to-year production magnitude differences. The temporal water-use pattern of the two irrigated basins was indicative of the cropping patterns specific to each region. Our results were comparable to field reports and to estimates based on watershed-wide crop water-balance model results. For example, both methods found that the 2003 seasonal ETa was the highest of all six years. The method also captured water management scenarios where a unique year-to-year variability was identified in addition to water-use differences between

  12. A coupled remote sensing and simplified surface energy balance approach to estimate actual evapotranspiration from irrigated fields

    USGS Publications Warehouse

    Senay, G.B.; Budde, M.; Verdin, J.P.; Melesse, Assefa M.

    2007-01-01

    Accurate crop performance monitoring and production estimation are critical for timely assessment of the food balance of several countries in the world. Since 2001, the Famine Early Warning Systems Network (FEWS NET) has been monitoring crop performance and relative production using satellite-derived data and simulation models in Africa, Central America, and Afghanistan where ground-based monitoring is limited because of a scarcity of weather stations. The commonly used crop monitoring models are based on a crop water-balance algorithm with inputs from satellite-derived rainfall estimates. These models are useful to monitor rainfed agriculture, but they are ineffective for irrigated areas. This study focused on Afghanistan, where over 80 percent of agricultural production comes from irrigated lands. We developed and implemented a Simplified Surface Energy Balance (SSEB) model to monitor and assess the performance of irrigated agriculture in Afghanistan using a combination of 1-km thermal data and 250m Normalized Difference Vegetation Index (NDVI) data, both from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor. We estimated seasonal actual evapotranspiration (ETa) over a period of six years (2000-2005) for two major irrigated river basins in Afghanistan, the Kabul and the Helmand, by analyzing up to 19 cloud-free thermal and NDVI images from each year. These seasonal ETa estimates were used as relative indicators of year-to-year production magnitude differences. The temporal water-use pattern of the two irrigated basins was indicative of the cropping patterns specific to each region. Our results were comparable to field reports and to estimates based on watershed-wide crop water-balance model results. For example, both methods found that the 2003 seasonal ETa was the highest of all six years. The method also captured water management scenarios where a unique year-to-year variability was identified in addition to water-use differences between

  13. Chapter A6. Field Measurements

    USGS Publications Warehouse

    Wilde, Franceska D., (Edited By); Radtke, Dean B.

    1998-01-01

    The National Field Manual for the Collection of Water-Quality Data (National Field Manual) provides guidelines and standard procedures for U.S. Geological Survey (USGS) personnel who collect data used to assess the quality of the Nation's surface-water and ground-water resources. Chapter A6 presents procedures and guidelines for the collection of data on air and water temperature, and on dissolved-oxygen concentrations, specific electrical conductance, pH, reduction-oxidation potential, alkalinity, and turbidity in water. Each chapter of the National Field Manual is published separately and revised periodically. Newly published and revised chapters are posted on the World Wide Web on the USGS page 'National Field Manual for the Collection of Water-Quality Data.' The URL for this page is http://pubs.water.usgs.gov/twri9A (accessed August 6, 2005).

  14. Thermal system field performance predictions from laboratory and field measurements

    NASA Astrophysics Data System (ADS)

    Burks, Stephen D.; Haefner, David P.; Teaney, Brian P.; Doe, Joshua M.

    2016-05-01

    Laboratory measurements on thermal imaging systems are critical to understanding their performance in a field environment. However, it is rarely a straightforward process to directly inject thermal measurements into thermal performance modeling software to acquire meaningful results. Some of the sources of discrepancies between laboratory and field measurements are sensor gain and level, dynamic range, sensor display and display brightness, and the environment where the sensor is operating. If measurements for the aforementioned parameters could be performed, a more accurate description of sensor performance in a particular environment is possible. This research will also include the procedure for turning both laboratory and field measurements into a system model.

  15. Erosion by Wind: Field Measurement

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Wind erosion and deposition results when wind moves soil from a bare susceptible surface to another location downwind. Although placement of permanent vertical references such as pins or rods has been used to measure soil redistribution, it is more commonly measured by capturing sediment moving dur...

  16. Correlation between quantitative fit factors and workplace protection factors measured in actual workplace environments at a steel foundry.

    PubMed

    Zhuang, Ziqing; Coffey, Christopher C; Jensen, Paul A; Campbell, Donald L; Lawrence, Robert B; Myers, Warren R

    2003-01-01

    Past studies have found little or no correlation between workplace protection factors (WPFs) and quantitative fit factors (FFs). This study investigated the effect of good- and poor-fitting half-facepiece, air-purifying respirators on protection in actual workplace environments at a steel foundry and the correlation between WPFs and FFs. Fifteen burners and welders, who wore respirators voluntarily, and chippers participated in this study. Each subject was fit-tested with two respirator models each with three sizes, for a total of six fit-tests. Models and sizes were assigned this way to provide a wide range of FFs among study participants. Each worker donned the respirator twice per day (at the beginning of the shift and following the lunch break) for 2 days. Quantitative FFs were first obtained for each donning using the PortaCount Plus trade mark in a separate room. Without redonning the respirators, workers performed normal work for 1 to 2 hours, and WPFs were measured by collecting ambient and in-facepiece samples simultaneously. A second fit-test was conducted without disturbing the respirator. FFs were obtained by averaging the results from the first and second fit-tests. The resulting FFs had a geometric mean (GM) of 400 (range=10-6010) and a geometric standard deviation (GSD) of 6.1. Of the 55 valid donnings, 43 were good fitting (FFs> or =100) and 12 were poor fitting (FFs<100). The WPFs had a GM of 920 (range=13-230,000) and a GSD of 17.8. The WPFs were found to be significantly correlated with the FFs (R(2)=.55 and p-value=.0001). Therefore, FF was shown to be a meaningful indicator of respirator performance in actual workplace environments. PMID:14674806

  17. Measurements of Solar Vector Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J. (Editor)

    1985-01-01

    Various aspects of the measurement of solar magnetic fields are presented. The four major subdivisions of the study are: (1) theoretical understanding of solar vector magnetic fields; (3) techniques for interpretation of observational data; and (4) techniques for data display.

  18. Comparing Laboratory and Field Measured Bioaccumulation Endpoints

    EPA Science Inventory

    The report presents an approach that allows comparisons of all laboratory and field bioaccumulation endpoints measurements. The approach will enable the inclusion of large amounts of field data into evaluations of bioaccumulation potential for legacy chemicals. Currently, these...

  19. Microwave field pattern measurement for EMC study

    NASA Astrophysics Data System (ADS)

    Takagi, Tasuku

    The author has developed a robotic system for automatic measurement of a microwave field. An antenna (sensor) scans a field space to be measured. The data of each point in the scanned space is stored in memories and processed to display or print out as a field pattern. All systems are controlled by a microcomputer. Scattering field by an object to be studied can be obtained without use of a special measuring site by obtaining a difference between the field intensity without the object and that with the object. Several measuring examples are presented, such as a field pattern in a living space, diffraction pattern around the living body, pattern measurement of an effect of aprons for protection from the microwave field, and so on.

  20. The actual measurements at the tide gauges do not support strongly accelerating twentieth-century sea-level rise reconstructions

    NASA Astrophysics Data System (ADS)

    Parker, A.

    2016-03-01

    Contrary to what is claimed by reconstructions of the Global Mean Sea Level (GMSL) indicating accelerating sea level rates of rise over the twentieth-century, the actual measurements at the tide gauges show the sea levels have not risen nor accelerated that much. The most recent estimation by Hay et al [1] of the twentieth-century global mean sea level (GMSL) rise is the last attempt to give exact reconstructions without having enough information of the state of the world oceans over a century where unfortunately the good measurements were not that many. The information on relative rates of rise at the tide gauges and land subsidence of global positioning system (GPS) domes suggest the relative rate of rise is about 0.25mm/year, without any detectable acceleration. [The naïve average of all the world tide gauges of sufficient quality and length of the Permanent Service to Mean Sea Level (PSMSL) data base], Both the relative rates of rise at the tide gauges and the land vertical velocity of GPS domes of the Système d'Observation du Niveau des Eaux Littorales (SONEL) data base are strongly variable in space and time to make a nonsense the GMSL estimation.

  1. The actual measurements at the tide gauges do not support strongly accelerating twentieth-century sea-level rise reconstructions

    NASA Astrophysics Data System (ADS)

    Parker, A.

    2016-03-01

    Contrary to what is claimed by reconstructions of the Global Mean Sea Level (GMSL) indicating accelerating sea level rates of rise over the twentieth-century, the actual measurements at the tide gauges show the sea levels have not risen nor accelerated that much. The most recent estimation by Hay et al of the twentieth-century global mean sea level (GMSL) rise is the last attempt to give exact reconstructions without having enough information of the state of the world oceans over a century where unfortunately the good measurements were not that many. The information on relative rates of rise at the tide gauges and land subsidence of global positioning system (GPS) domes suggest the relative rate of rise is about 0.25mm/year, without any detectable acceleration. [The naïve average of all the world tide gauges of sufficient quality and length of the Permanent Service to Mean Sea Level (PSMSL) data base], Both the relative rates of rise at the tide gauges and the land vertical velocity of GPS domes of the Système d'Observation du Niveau des Eaux Littorales (SONEL) data base are strongly variable in space and time to make a nonsense the GMSL estimation.

  2. The Measurement of Magnetic Fields

    ERIC Educational Resources Information Center

    Berridge, H. J. J.

    1973-01-01

    Discusses five experimental methods used by senior high school students to provide an accurate calibration curve of magnet current against the magnetic flux density produced by an electromagnet. Compares the relative merits of the five methods, both as measurements and from an educational viewpoint. (JR)

  3. Magnetic space-based field measurements

    NASA Technical Reports Server (NTRS)

    Langel, R. A.

    1981-01-01

    Satellite measurements of the geomagnetic field began with the launch of Sputnik 3 in May 1958 and have continued sporadically in the intervening years. A list of spacecraft that have made significant contributions to an understanding of the near-earth geomagnetic field is presented. A new era in near-earth magnetic field measurements began with NASA's launch of Magsat in October 1979. Attention is given to geomagnetic field modeling, crustal magnetic anomaly studies, and investigations of the inner earth. It is concluded that satellite-based magnetic field measurements make global surveys practical for both field modeling and for the mapping of large-scale crustal anomalies. They are the only practical method of accurately modeling the global secular variation. Magsat is providing a significant contribution, both because of the timeliness of the survey and because its vector measurement capability represents an advance in the technology of such measurements.

  4. Actual evapotranspiration for a reference crop within measured and future changing climate periods in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Katerji, Nader; Rana, Gianfranco; Ferrara, Rossana Monica

    2016-05-01

    The study compares two formulas for calculating the daily evapotranspiration ET0 for a reference crop. The first formula was proposed by Allen et al. (AL), while the second one was proposed by Katerji and Perrier with the addition of the carbon dioxide (CO2) effect on evapotranspiration (KP). The study analyses the impact of the calculation by the two formulas on the irrigation requirement (IR). Both formulas are based on the Penman-Monteith equation but adopt different approaches for parameterising the canopy resistance r c . In the AL formula, r c is assumed constant and not sensitive to climate change, whereas in the KP formula, r c is first parameterised as a function of climatic variables, then ET0 is corrected for the air CO2 concentration. The two formulas were compared in two periods. The first period involves data from two sites in the Mediterranean region within a measured climate change period (1981-2006) when all the input climatic variables were measured. The second period (2070-2100) involves data from a future climate change period at one site when the input climatic variables were forecasted for two future climate scenarios (A2 and B2). The annual cumulated values of ET0 calculated by the AL formula are systematically lower than those determined by the KP formula. The differences between the ET0 estimation with the AL and KP formulas have a strong impact on the determination of the IR for the reference crop. In fact, for the two periods, the annual values of IR when ET0 is calculated by the AL formula are systematically lower than those calculated by the KP formula. For the actual measured climate change period, this reduction varied from 26 to 28 %, while for the future climate change period, it varied based on the scenario from 16 % (A2) to 20 % (B2).

  5. Urban thermal environment measurements and numerical simulation for an actual complex urban area covering a large district heating and cooling system in summer

    NASA Astrophysics Data System (ADS)

    Huang, Hong; Ooka, Ryozo; Kato, Shinsuke

    Urban thermal situation is thought to have a great influence on the air quality in urban areas. In recent years, the urban thermal environment has become worse, such as the days on which the temperature goes above 30 °C, the sultry nights and heat stroke increase due to changes in terrestrial cover and increased anthropogenic heat emission accompanied by urbanization. Therefore, the urban thermal environment should be carefully investigated and accurately analyzed for a better study of the air quality. Here, in order to study the urban thermal environment in summer, (1) the actual status of an urban thermal environment in a complex urban area covering a large district heating and cooling (DHC) system in Tokyo is investigated using field measurements, and (2) a numerical simulation program which can be adapted to complex urban areas coupled with convection, radiation and conduction is developed and used to predict the urban thermal environment. Wind velocity, temperature and humidity are obtained from the simulation, which shows good agreement with results of the field measurement. The spatial distribution of the standard effective temperature (SET *), the comprehensive index of human thermal comfort, is also calculated using the above results, to estimate the thermal comfort at the pedestrian level. This urban thermal numerical simulation can be coupled with air pollution dispersion and chemical processes to provide a more precise air quality prediction in complex urban areas.

  6. Magnetic Field Response Measurement Acquisition System

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor, Bryant D.; Shams, Qamar A.; Fox, Robert L.

    2005-01-01

    A measurement acquisition method that alleviates many shortcomings of traditional measurement systems is presented in this paper. The shortcomings are a finite number of measurement channels, weight penalty associated with measurements, electrical arcing, wire degradations due to wear or chemical decay and the logistics needed to add new sensors. The key to this method is the use of sensors designed as passive inductor-capacitor circuits that produce magnetic field responses. The response attributes correspond to states of physical properties for which the sensors measure. A radio frequency antenna produces a time-varying magnetic field used to power the sensor and receive the magnetic field response of the sensor. An interrogation system for discerning changes in the sensor response is presented herein. Multiple sensors can be interrogated using this method. The method eliminates the need for a data acquisition channel dedicated to each sensor. Methods of developing magnetic field response sensors and the influence of key parameters on measurement acquisition are discussed.

  7. MAGNETIC FIELD MEASUREMENTS FOR FAST-CHANGING MAGNETIC FIELDS.

    SciTech Connect

    JAIN, A.; ESCALLIER, J.; GANETIS, G.; LOUIE, W.; MARONE, A.; THOMAS. R.; WANDERER, P.

    2004-10-03

    Several recent applications for fast ramped magnets have been found that require rapid measurement of the field quality during the ramp. (In one instance, accelerator dipoles will be ramped at 1 T/sec, with measurements needed to the accuracy typically required for accelerators.) We have built and tested a new type of magnetic field measuring system to meet this need. The system consists of 16 stationary pickup windings mounted on a cylinder. The signals induced in the windings in a changing magnetic field are sampled and analyzed to obtain the field harmonics. To minimize costs, printed circuit boards were used for the pickup windings and a combination of amplifiers and ADPs used for the voltage readout system. New software was developed for the analysis. Magnetic field measurements of a model dipole developed for the SIS200 accelerator at GSI are presented. The measurements are needed to insure that eddy currents induced by the fast ramps do not impact the field quality needed for successful accelerator operation.

  8. Attracting Students to the Field of Measurement

    ERIC Educational Resources Information Center

    Finney, Sara J.; Pastor, Dena A.

    2012-01-01

    To address the shortage of professionals in measurement, it is essential that we make young career-seekers aware that measurement is an option as a profession. In this paper, we discuss how creating a strong pipeline of students into our field involves personal interactions between faculty representing the graduate programs in measurement and…

  9. MICE Spectrometer Solenoid Magnetic Field Measurements

    SciTech Connect

    Leonova, M.

    2013-09-01

    The Muon Ionization Cooling Experiment (MICE) is designed to demonstrate ionization cooling in a muon beam. Its goal is to measure a 10% change in transverse emittance of a muon beam going through a prototype Neutrino Factory cooling channel section with an absolute measurement accuracy of 0.1%. To measure emittances, MICE uses two solenoidal spectrometers, with Solenoid magnets designed to have 4 T fields, uniform at 3 per mil level in the tracking volumes. Magnetic field measurements of the Spectrometer Solenoid magnet SS2, and analysis of coil parameters for input into magnet models will be discussed.

  10. Magnetic space-based field measurements

    NASA Technical Reports Server (NTRS)

    Langel, R. A.

    1981-01-01

    Because the near Earth magnetic field is a complex combination of fields from outside the Earth of fields from its core and of fields from its crust, measurements from space prove to be the only practical way to obtain timely, global surveys. Due to difficulty in making accurate vector measurements, early satellites such as Sputnik and Vanguard measured only the magnitude survey. The attitude accuracy was 20 arc sec. Both the Earth's core fields and the fields arising from its crust were mapped from satellite data. The standard model of the core consists of a scalar potential represented by a spherical harmonics series. Models of the crustal field are relatively new. Mathematical representation is achieved in localized areas by arrays of dipoles appropriately located in the Earth's crust. Measurements of the Earth's field are used in navigation, to map charged particles in the magnetosphere, to study fluid properties in the Earth's core, to infer conductivity of the upper mantels, and to delineate regional scale geological features.

  11. Magnetic Field Response Measurement Acquisition System

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E.; Taylor,Bryant D.; Shams, Qamar A.; Fox, Robert L.

    2007-01-01

    This paper presents a measurement acquisition method that alleviates many shortcomings of traditional measurement systems. The shortcomings are a finite number of measurement channels, weight penalty associated with measurements, electrical arcing, wire degradations due to wear or chemical decay and the logistics needed to add new sensors. Wire degradation has resulted in aircraft fatalities and critical space launches being delayed. The key to this method is the use of sensors designed as passive inductor-capacitor circuits that produce magnetic field responses. The response attributes correspond to states of physical properties for which the sensors measure. Power is wirelessly provided to the sensing element by using Faraday induction. A radio frequency antenna produces a time-varying magnetic field used to power the sensor and receive the magnetic field response of the sensor. An interrogation system for discerning changes in the sensor response frequency, resistance and amplitude has been developed and is presented herein. Multiple sensors can be interrogated using this method. The method eliminates the need for a data acquisition channel dedicated to each sensor. The method does not require the sensors to be near the acquisition hardware. Methods of developing magnetic field response sensors and the influence of key parameters on measurement acquisition are discussed. Examples of magnetic field response sensors and the respective measurement characterizations are presented. Implementation of this method on an aerospace system is discussed.

  12. "I Actually Learned a Lot from This": A Field Assignment to Prepare Future Preservice Math Teachers for Culturally Diverse Classrooms

    ERIC Educational Resources Information Center

    Downey, Jayne A.; Cobbs, Georgia A.

    2007-01-01

    Teacher education programs are cognizant of the need to prepare preservice teachers (PTs) to work effectively with children from diverse cultural backgrounds. Well-constructed field experiences can help PTs develop awareness and gain understanding of important cultural considerations related to effective teaching and learning (Sleeter, 2001). This…

  13. Intended release and actual retention of alfalfa leafcutting bees (hymenoptera: megachilidae) for pollination in commercial alfalfa seed fields

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Low, medium, and high stocking densities of Megachile rotundata, the alfalfa leafcutting bee, were released over four years in three research plots of Utah alfalfa planted at seed-production rates. A low number of bees (46-79% of released) survived the incubation and field emergence processes, and ...

  14. Dark field electron holography for strain measurement.

    PubMed

    Béché, A; Rouvière, J L; Barnes, J P; Cooper, D

    2011-02-01

    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. PMID:21333860

  15. Improved visualization of flow field measurements

    NASA Technical Reports Server (NTRS)

    Miles, Jeffrey Hilton

    1991-01-01

    A capability is proposed that makes it feasible to apply to measured flow field data the visualization tools developed to display numerical solutions for computational fluid dynamic problems. The measurement monitor surface (MMS) methodology was used for the analysis of flow field measurements within a low-aspect-ratio transonic axial-flow fan rotor acquired with two-dimensional laser anemometry. It is shown that the MMS method may be utilized to generate input for the multidimensional processing and analytical tools developed for numerical flow field simulation data. Thus an experimenter utilizing an interactive graphics program could illustrate scalar quantities such as Mach number by profiles, contour lines, carpet plots, and surfaces employing various color intensities. Also, flow directionality can be shown by the display of vector fields and particle traces.

  16. Field measurement of cotton seedling evapotranspiration

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Information on cotton evapotranspiration (ET) during the seedling growth stage and under field conditions is scarce because ET is a difficult parameter to measure. Our objective was to use weighable lysimeters to measure daily values of cotton seedling ET. We designed and built plastic weighable mic...

  17. Testing an Energy Balance Model for Estimating Actual Evapotranspiration Using Remotely Sensed Data. [Hannover, West Germany barley and wheat fields

    NASA Technical Reports Server (NTRS)

    Gurney, R. J.; Camillo, P. J.

    1985-01-01

    An energy-balance model is used to estimate daily evapotranspiration for 3 days for a barley field and a wheat field near Hannover, Federal Republic of Germany. The model was calibrated using once-daily estimates of surface temperatures, which may be remotely sensed. The evaporation estimates were within the 95% error bounds of independent eddy correlation estimates for the daytime periods for all three days for both sites, but the energy-balance estimates are generally higher; it is unclear which estimate is biassed. Soil moisture in the top 2 cm of soil, which may be remotely sensed, may be used to improve these evaporation estimates under partial ground cover. Sensitivity studies indicate the amount of ground data required is not excessive.

  18. Full field imaging based instantaneous hyperspectral absolute refractive index measurement

    SciTech Connect

    Baba, Justin S; Boudreaux, Philip R

    2012-01-01

    Multispectral refractometers typically measure refractive index (RI) at discrete monochromatic wavelengths via a serial process. We report on the demonstration of a white light full field imaging based refractometer capable of instantaneous multispectral measurement of absolute RI of clear liquid/gel samples across the entire visible light spectrum. The broad optical bandwidth refractometer is capable of hyperspectral measurement of RI in the range 1.30 1.70 between 400nm 700nm with a maximum error of 0.0036 units (0.24% of actual) at 414nm for a = 1.50 sample. We present system design and calibration method details as well as results from a system validation sample.

  19. Magnetic Field Response Measurement Acquisition System

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor); Shams, Qamar A. (Inventor); Fox, Robert L. (Inventor); Fox, Christopher L. (Inventor); Fox, Melanie L. (Inventor); Bryant, Robert G. (Inventor)

    2006-01-01

    Magnetic field response sensors designed as passive inductor-capacitor circuits produce magnetic field responses whose harmonic frequencies correspond to states of physical properties for which the sensors measure. Power to the sensing element is acquired using Faraday induction. A radio frequency antenna produces the time varying magnetic field used for powering the sensor, as well as receiving the magnetic field response of the sensor. An interrogation architecture for discerning changes in sensor s response kequency, resistance and amplitude is integral to the method thus enabling a variety of measurements. Multiple sensors can be interrogated using this method, thus eliminating the need to have a data acquisition channel dedicated to each sensor. The method does not require the sensors to be in proximity to any form of acquisition hardware. A vast array of sensors can be used as interchangeable parts in an overall sensing system.

  20. Electric Field Quantitative Measurement System and Method

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R. (Inventor)

    2016-01-01

    A method and system are provided for making a quantitative measurement of an electric field. A plurality of antennas separated from one another by known distances are arrayed in a region that extends in at least one dimension. A voltage difference between at least one selected pair of antennas is measured. Each voltage difference is divided by the known distance associated with the selected pair of antennas corresponding thereto to generate a resulting quantity. The plurality of resulting quantities defined over the region quantitatively describe an electric field therein.

  1. Actual Condition of Paddy Field Levee Maintenance by Various Farm Households including Large-scale Farming in the Developed Land Renting Area

    NASA Astrophysics Data System (ADS)

    Sakata, Yasuyo

    The survey of interview, resource acquisition, photographic operation, and questionnaire were carried out in the “n” Community in the “y” District in Hakusan City in Ishikawa Prefecture to investigate the actual condition of paddy field levee maintenance in the area where land-renting market was proceeding, large-scale farming was dominant, and the problems of geographically scattered farm-land existed. In the study zone, 1) an agricultural production legal person rent-cultivated some of the paddy fields and maintained the levees, 2) another agricultural production legal person rent-cultivated some of the soy bean fields for crop changeover and land owners maintained the levees. The results indicated that sufficient maintenance was executed on the levees of the paddy fields cultivated by the agricultural production legal person, the soy bean fields for crop changeover, and the paddy fields cultivated by the land owners. Each reason is considered to be the managerial strategy, the economic incentive, the mutual monitoring and cross-regulatory mechanism, etc.

  2. Electric field measurements from Halley, Antarctica

    NASA Astrophysics Data System (ADS)

    Nicoll, Keri; Harrison, R. Giles

    2016-04-01

    Antarctica is a unique location for the study of atmospheric electricity. Not only is it one of the most pollutant free places on Earth, but its proximity to the south magnetic pole means that it is an ideal location to study the effects of solar variability on the atmospheric electric field. This is due to the reduced shielding effect of the geomagnetic field at the poles which leads to a greater flux of incoming Galactic Cosmic Rays (GCRs) as well as an increased probability of energetic particle precipitation from SEPs and relativistic electrons. To investigate such effects, two electric field mills of different design were installed at the British Antarctic Survey Halley base in February 2015 (75. 58 degrees south, 26.66 degrees west). Halley is situated on the Brunt Ice Shelf in the south east of the Weddell Sea and has snow cover all year round. Preliminary analysis has focused on selection of fair weather criteria using wind speed and visibility measurements which are vital to assess the effects of falling snow, blowing snow and freezing fog on the electric field measurements. When the effects of such adverse weather conditions are removed clear evidence of the characteristic Carnegie Curve diurnal cycle exists in the Halley electric field measurements (with a mean value of 50V/m and showing a 40% peak to peak variation in comparison to the 34% variation in the Carnegie data). Since the Carnegie Curve represents the variation in thunderstorm activity across the Earth, its presence in the Halley data confirms the presence of the global atmospheric electric circuit signal at Halley. The work presented here will discuss the details of the Halley electric field dataset, including the variability in the fair weather measurements, with a particular focus on magnetic field fluctuations.

  3. Documents Similarity Measurement Using Field Association Terms.

    ERIC Educational Resources Information Center

    Atlam, El-Sayed; Fuketa, M.; Morita, K.; Aoe, Jun-ichi

    2003-01-01

    Discussion of text analysis and information retrieval and measurement of document similarity focuses on a new text manipulation system called FA (field association)-Sim that is useful for retrieving information in large heterogeneous texts and for recognizing content similarity in text excerpts. Discusses recall and precision, automatic indexing…

  4. Rectangular subsonic jet flow field measurements

    NASA Technical Reports Server (NTRS)

    Morrison, Gerald L.; Swan, David H.

    1990-01-01

    Flow field measurements of three subsonic rectangular cold air jets are presented. The three cases had aspect ratios of 1x2, 1x4 at a Mach number of 0.09 and an aspect ratio of 1x2 at a Mach number of 0.9. All measurements were made using a 3-D laser Doppler anemometer system. The data includes the mean velocity vector, all Reynolds stress tensor components, turbulent kinetic energy and velocity correlation coefficients. The data are presented in tabular and graphical form. No analysis of the measured data or comparison to other published data is made.

  5. Uranium isotope ratio measurements in field settings

    SciTech Connect

    Shaw, R.W.; Barshick, C.M.; Young, J.P.; Ramsey, J.M.

    1997-06-01

    The authors have developed a technique for uranium isotope ratio measurements of powder samples in field settings. Such a method will be invaluable for environmental studies, radioactive waste operations, and decommissioning and decontamination operations. Immediate field data can help guide an ongoing sampling campaign. The measurement encompasses glow discharge sputtering from pressed sample hollow cathodes, high resolution laser spectroscopy using conveniently tunable diode lasers, and optogalvanic detection. At 10% {sup 235}U enrichment and above, the measurement precision for {sup 235}U/({sup 235}U+{sup 238}U) isotope ratios was {+-}3%; it declined to {+-}15% for 0.3% (i.e., depleted) samples. A prototype instrument was constructed and is described.

  6. Recommendations for field measurements of aircraft noise

    NASA Technical Reports Server (NTRS)

    Marsh, A. H.

    1982-01-01

    Specific recommendations for environmental test criteria, data acquisition procedures, and instrument performance requirements for measurement of noise levels produced by aircraft in flight are provided. Recommendations are also given for measurement of associated airplane and engine parameters and atmospheric conditions. Recommendations are based on capabilities which were available commercially in 1981; they are applicable to field tests of aircraft flying subsonically past microphones located near the surface of the ground either directly under or to the side of a flight path. Aircraft types covered by the recommendations include fixed-wing airplanes powered by turbojet or turbofan engines or by propellers. The recommended field-measurement procedures are consistent with assumed requirements for data processing and analysis.

  7. Electric Field Effects in RUS Measurements

    SciTech Connect

    Darling, Timothy W; Ten Cate, James A; Allured, Bradley; Carpenter, Michael A

    2009-09-21

    Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material - a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the 'statistical residual' strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods.

  8. Electric field effects in RUS measurements.

    PubMed

    Darling, Timothy W; Allured, Bradley; Tencate, James A; Carpenter, Michael A

    2010-02-01

    Much of the power of the Resonant Ultrasound Spectroscopy (RUS) technique is the ability to make mechanical resonance measurements while the environment of the sample is changed. Temperature and magnetic field are important examples. Due to the common use of piezoelectric transducers near the sample, applied electric fields introduce complications, but many materials have technologically interesting responses to applied static and RF electric fields. Non-contact optical, buffered, or shielded transducers permit the application of charge and externally applied electric fields while making RUS measurements. For conducting samples, in vacuum, charging produces a small negative pressure in the volume of the material--a state rarely explored. At very high charges we influence the electron density near the surface so the propagation of surface waves and their resonances may give us a handle on the relationship of electron density to bond strength and elasticity. Our preliminary results indicate a charge sign dependent effect, but we are studying a number of possible other effects induced by charging. In dielectric materials, external electric fields influence the strain response, particularly in ferroelectrics. Experiments to study this connection at phase transformations are planned. The fact that many geological samples contain single crystal quartz suggests a possible use of the piezoelectric response to drive vibrations using applied RF fields. In polycrystals, averaging of strains in randomly oriented crystals implies using the "statistical residual" strain as the drive. The ability to excite vibrations in quartzite polycrystals and arenites is explored. We present results of experimental and theoretical approaches to electric field effects using RUS methods. PMID:19850314

  9. Electric field measurements with stratospheric balloons

    NASA Technical Reports Server (NTRS)

    Iversen, I. B.

    1989-01-01

    Electric fields and currents in the middle atmosphere are important elements of the modern picture of this region. Balloon instruments, reaching the level of the stratosphere, were used extensively for the experimental work. The research has shown good progress, both in the MAP period and in the years before and after. The knowledge was increased about, e.g., the upper atmosphere potential, the electric properties of the medium itself and about the coupling with magnetospheric (ionospheric) fields and currents. Also various measurements have brought about a discussion of the possible existence of hitherto unknown sources. Throughout the MAP period the work on a possible definition of an electric index has continued.

  10. Measurements of magnetic fields in solar prominences

    NASA Technical Reports Server (NTRS)

    Deglinnocenti, Egidio Landi

    1986-01-01

    Magnetic fields can be measured, in solar prominences, by means of two different basic mechanisms that are responsible for the introduction (or the reduction) of a given amount of polarization in spectral lines: these are the Zeeman effect and the Hanle effect. Through the splitting of the magnetic components of a spectral line, the Zeeman effect is capable of introducing a certain amount of circular polarization across the line profile. The Hanle effect consist of a modification of the linear polarization that is induced in spectral lines by the anisotropic illumination of the prominence plasma by the photospheric radiation field. These two effects are briefly discussed.

  11. Comparison of actual evaporation from water surface measured by GGI-3000 evaporimeter with values calculated by the Penman equation

    NASA Astrophysics Data System (ADS)

    Kohu, Mojmír; Rožnovský, Jaroslav; Knozová, Grazyna

    2014-09-01

    Information about water evaporation is essential for the calculation of water balance. Evaporation, however, is a very complex physical process and it is therefore difficult to quantify. Evaporation measurements from the weather station network of the Czech Hydrometeorological Institute between 1968 and 2011 were performed using the evaporimeter GGI-3000. Evaporation was calculated using modified standard method based on FAO. The aim of the article was to compare the measured values and calculations. It has been found that the evaporation values from water surface calculated using the empirical equation are usually higher than the measured values by on average 0.8 mm, in extreme cases even 6.9 mm. The measured data shows higher variability than the calculated values, which means that correlations between series are not strong, the correlation coefficient being 0.7. Nevertheless the findings can be used for homogenization of series measured by the GGI-3000 evaporimeter.

  12. Methyl bromide volatility measurements from treated fields

    SciTech Connect

    Majewski, M.S.; Woodrow, J.E.; Seiber, J.N. |

    1995-12-31

    Methyl bromide is used as an agricultural soil fumigant and concern is growing over the role it may play in the depletion of stratospheric ozone. Methyl bromide is applied using various techniques and little is known about how much of the applied fumigant volatilizes into the atmosphere after application. The post-application volatilization losses of methyl bromide from two fields using different application practices were measured using an aerodynamic-gradient technique. One field was covered with a high-barrier plastic film tarp during application and the other was left uncovered, but the furrows made by the injection shanks were bedded over. The cumulative volatilization losses from the tarped field were 22% of the nominal application within the first 5 days of the experiment and about 32% of the nominal application within 9 days including the one day after the tarp was removed on day 8. The nontarped field lost 89%of the nominal application by volatilization in 5 days. The error associated, with each flux measurement, as well as variations in daily flux losses with differing sampling period lengths show the degree of variability inherent in this type of study.

  13. Fast excitation wiggler field measurement results

    SciTech Connect

    Armendariz, J.; Gallardo, J.; Romano, T.; van Steenbergen, A.

    1992-08-01

    As part of the program of Inverse Free Electron Laser (IFEL) Accelerator Development, the development of fast excitation, planar wigglers with high K magnitude has been pursued. This paper discusses the observed characteristics of a variable period length, tapered, wiggler as well as the procedures of measurement. The behaviour of a constant period length magnet with varying Vanadium Permendur (VaP) and field reflector thickness is also discussed.

  14. Ultrasound field measurement using a binary lens

    PubMed Central

    Clement, G.T.; Nomura, H.; Kamakura, T.

    2014-01-01

    Field characterization methods using a scattering target in the absence of a point-like receiver have been well described in which scattering is recorded by a relatively large receiver located outside the field of measurement. Unfortunately, such methods are prone to artifacts due to averaging across the receiver surface. To avoid this problem while simultaneously increasing the gain of a received signal, the present study introduces a binary plate lens designed to focus spherically-spreading waves onto a planar region having a nearly-uniform phase proportional to that of the target location. The lens is similar to a zone plate, but modified to produce a biconvex-like behavior, such that it focuses both planar and spherically spreading waves. A measurement device suitable for characterizing narrowband ultrasound signals in air is designed around this lens by coupling it to a target and planar receiver. A prototype device is constructed and used to characterize the field of a highly-focused 400 kHz air transducer along 2 radial lines. Comparison of the measurements with numeric predictions formed from nonlinear acoustic simulation showed good relative pressure correlation, with mean differences of 10% and 12% over center 3dB FWHM drop and 12% and 17% over 6dB. PMID:25643084

  15. Aerodynamic Flow Field Measurements for Automotive Systems

    NASA Technical Reports Server (NTRS)

    Hepner, Timothy E.

    1999-01-01

    The design of a modern automotive air handling system is a complex task. The system is required to bring the interior of the vehicle to a comfortable level in as short a time as possible. A goal of the automotive industry is to predict the interior climate of an automobile using advanced computational fluid dynamic (CFD) methods. The development of these advanced prediction tools will enable better selection of engine and accessory components. The goal of this investigation was to predict methods used by the automotive industry. To accomplish this task three separate experiments were performed. The first was a laboratory setup where laser velocimeter (LV) flow field measurements were made in the heating and air conditioning unit of a Ford Windstar. The second involved flow field measurements in the engine compartment of a Ford Explorer, with the engine running idle. The third mapped the flow field exiting the center dashboard panel vent inside the Explorer, while the circulating fan operated at 14 volts. All three experiments utilized full-coincidence three-component LV systems. This enabled the mean and fluctuating velocities to be measured along with the Reynolds stress terms.

  16. Preliminary Study on the Radar Vegetation Index (RVI) Application to Actual Paddy Fields by ALOS/PALSAR Full-polarimetry SAR Data

    NASA Astrophysics Data System (ADS)

    Yamada, Y.

    2015-04-01

    Kim and van Zyl (2001) proposed a kind of radar vegetation index (RVI). RVI = 4*min(λ1, λ2, λ3) / (λ1 + λ2 + λ3) They modified the equation as follows. (2009) RVI = 8 * σ0hv / (σ0hh + σ0vv +σ0hv ) by L-band full-polarimetric SAR data. They applied it into rice crop and soybean. (Y.Kim, T.Jackson et al., 2012) They compared RVI for L-, C- and X-bands to crop growth data, LAI and NDVI. They found L-band RVI was well correlated with Vegetation Water Content, LAI and NDVI. But the field data were collected by the multifrequency polarimetric scatterometer. The platform height was 4.16 meters from the ground. The author tried to apply the method to actual paddy fields near Tsukuba science city in Japan using ALOS/PALSAR, full-polarimetry L-band SAR data. The staple crop in Eastern Asia is rice and paddy fields are dominant land use. A rice-planting machine comes into wide use in this areas. The young rice plants were bedded regularly ridged line in the paddy fields by the machine. The space between two ridges of rice plants is about 30 cm and the wave length of PALSAR sensor is about 23 cm. Hence the Bragg scattering will appear depending upon the direction of the ridges of paddy fields. Once the Bragg scattering occurs, the backscattering values from the pixels should be very high comparing the surrounding region. Therefore the radar vegetation index (RVI) would be saturated. The RVI did not follow the increasing of vegetation anymore. Japan has launched ALOS-2 satellite and it has PALSAR-2, L-band SAR. Therefore RVI application product by PALSAR-2 will be watched with deep interest.

  17. Rectangular subsonic jet flow field measurements

    NASA Technical Reports Server (NTRS)

    Morrison, Gerald L.; Swan, David H.

    1989-01-01

    Flow field measurements are presented of 3 subsonic rectangular cold air jets. The 3 cases presented had aspect ratios of 1 x 2, 1 x 4 at a Mach number of 0.09 and an aspect ratio of 1 x 2 at a Mach number of 0.9. All measurements were made using a 3-D laser Doppler anemoneter system. The presented data includes the mean velocity vector, all Reynolds stress tensor components, turbulent kinetic energy and velocity correlation coefficients. The data is presented in tabular and graphical form. No analysis of the measured data or comparison to other published data is made. All tabular data are available in ASCII format on MS-DOS compatible disks.

  18. Measurements of Photospheric and Chromospheric Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Lagg, Andreas; Lites, Bruce; Harvey, Jack; Gosain, Sanjay; Centeno, Rebecca

    2015-12-01

    The Sun is replete with magnetic fields, with sunspots, pores and plage regions being their most prominent representatives on the solar surface. But even far away from these active regions, magnetic fields are ubiquitous. To a large extent, their importance for the thermodynamics in the solar photosphere is determined by the total magnetic flux. Whereas in low-flux quiet Sun regions, magnetic structures are shuffled around by the motion of granules, the high-flux areas like sunspots or pores effectively suppress convection, leading to a temperature decrease of up to 3000 K. The importance of magnetic fields to the conditions in higher atmospheric layers, the chromosphere and corona, is indisputable. Magnetic fields in both active and quiet regions are the main coupling agent between the outer layers of the solar atmosphere, and are therefore not only involved in the structuring of these layers, but also for the transport of energy from the solar surface through the corona to the interplanetary space. Consequently, inference of magnetic fields in the photosphere, and especially in the chromosphere, is crucial to deepen our understanding not only for solar phenomena such as chromospheric and coronal heating, flares or coronal mass ejections, but also for fundamental physical topics like dynamo theory or atomic physics. In this review, we present an overview of significant advances during the last decades in measurement techniques, analysis methods, and the availability of observatories, together with some selected results. We discuss the problems of determining magnetic fields at smallest spatial scales, connected with increasing demands on polarimetric sensitivity and temporal resolution, and highlight some promising future developments for their solution.

  19. Measuring methyl bromide emissions from fields

    SciTech Connect

    Yates, S.R.; Gan, J.; Ernst, F.F.; Yates, M.V.

    1995-12-31

    Methyl bromide is used extensively for pest control. Recent evidence suggests that methyl bromide may react with stratospheric ozone and, due to the Clean Air Act, is scheduled for phase-out within the next 5 to 10 years. As indicated in a recent report from The National Agricultural Pesticide Impact Assessment Program, there will be substantial economic impact on the agricultural community if the use of methyl bromide is restricted. There are several areas of uncertainty concerning the agricultural use of methyl bromide. Foremost is the quantification of mass emitted to the atmosphere from agricultural fields. To address this, two field experiments were conducted to directly measure methyl bromide emissions. In the first experiment, methyl bromide was injected at approximately 25 cm depth and the soil was covered with 1 mil high-density polyethylene plastic. The second experiment was similar except that methyl bromide was injected at approximately 68 cm depth and the soil was not covered. From these experiments, the emission rate into the atmosphere and the subsurface transport of methyl bromide was determined. Both experiments include a field-scale mass balance to verify the accuracy of the flux-measurement methods as well as to check data consistency. The volatilization rate and mass lost was determined from estimates of the degradation and from several atmospheric and chamber flux methods.

  20. Laboratory Measurements of Astrophysical Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Murphy, Christopher; Miniati, F.; Edwards, M.; Constantin, C.; Everson, E.; Schaeffer, D.; Niemann, C.; Bingham, R.; Gargate, L.; Silva, L. O.; Bell, A. R.; Ravasio, A.; Woolsey, N.; Gregori, G.

    2010-05-01

    High Mach number shocks in astrophysical plasmas are believed to be responsible for cosmic-ray (CR) acceleration over a wide range of energies. CR radiation is a result of particle acceleration mediated by the long ranging and temporally sustained magnetic fields associated with these shocks. Since the magneto-hydrodynamic equations are scale invariant, astronomical systems may be simulated in laboratory experiments where megaparsecs and gigayears are studied in centimetres and microseconds. Here we present data on magnetic field amplification collected in an experiment conducted on the Nd:glass Phoenix laser system at UCLA. In this study, a plastic foil is exploded to produce a shock which is allowed to expand into sub-atmosphere density helium gas. Magnetic fields are measured in several positions and at a range of densities. The shock strength may be varied by modifying the energy and intensity of the laser incident on the foil target. Diagnosis of the magnetic fields combined with computer simulations give insight into generation mechanisms. The relevance of these results to previous theoretical and simulation work will be highlighted.

  1. New Methods of Magnetic Field Measurements

    NASA Astrophysics Data System (ADS)

    Kholtygin, A. F.

    2015-04-01

    The standard methods of magnetic field measurements, based on the relation between the Stokes V parameter and the first derivative of the line profile intensity were modified by applying a linear integral transform to both sides of this relation. We used the wavelet integral transform with the DOG wavelets. The key advantage of the proposed method is the effective suppression of the noise contribution both to the line profile and the Stokes V parameter. To test the proposed method, spectropolarimetric observations of the young O star θ1 Ori C were used. We also demonstrate that the smoothed Time Variation Spectra (smTVS) can be used as a tool for detecting the local stellar magnetic fields.

  2. Modified methods of stellar magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Kholtygin, A. F.

    2014-12-01

    The standard methods of the magnetic field measurement, based on an analysis of the relation between the Stokes V-parameter and the first derivative of the total line profile intensity, were modified by applying a linear integral operator \\hat{L} to both sides of this relation. As the operator \\hat{L}, the operator of the wavelet transform with DOG-wavelets is used. The key advantage of the proposed method is an effective suppression of the noise contribution to the line profile and the Stokes parameter V. The efficiency of the method has been studied using model line profiles with various noise contributions. To test the proposed method, the spectropolarimetric observations of the A0 star α2 CVn, the Of?p star HD 148937, and the A0 supergiant HD 92207 were used. The longitudinal magnetic field strengths calculated by our method appeared to be in good agreement with those determined by other methods.

  3. Field measurements in unwadeable natural hydraulic jumps

    NASA Astrophysics Data System (ADS)

    Valle, B.; Pasternack, G.

    2003-04-01

    Recent research in fluvial geomorphology has emphasized the development and application of digital terrain models to better understand process-form relations. However, field measurements in mountain channels have largely been restricted to low velocity or ephemeral flow conditions. To address this problem, a new high-resolution mechanical surveying system was developed at UC Davis and used to measure the 3D bed and water surface topographies of an unwadeable plunging hydraulic jump in the Cache Creek basin, CA. Labeled as the River Truss, the system is capable of making high-resolution form and process measurements over a 30 to 115 m2 area. Bed and water surface DTMs were derived from the field data using AutoCAD. River Truss precision was assessed by DTM differencing the hydraulic jump bed surface topography with a DTM developed from tacheometric survey at low base flows. Bed surface DTMs indicate significant spatial complexity of the underlying bed step in the supercritical flow region and significant downstream bed scour. Water surface DTMs indicate 3D complexity of the plunging flow surface and divergence from 1D free-fall theory. Further study will emphasize the development and deployment of process-based instrumentation such that the complex turbulent air-water flow dynamics associated with natural hydraulic jumps may be better understood. Also, a second generation River Truss that has a larger coverage area and automated data collection has been designed and is now being built.

  4. A Quantitative Measure of Field Illumination.

    PubMed

    Brown, Claire M; Reilly, Andrew; Cole, Richard W

    2015-07-01

    In this paper, we describe a statistically based algorithm to quantify the uniformity of illumination in an optical light microscopy imaging system that outputs a single quality factor (QF) score. The importance of homogeneous field illumination in quantitative light microscopy is well understood and often checked. However, there is currently no standard automatic quantitative measure of the uniformity of the field illumination. Images from 89 different laser-scanning confocal microscopes (LSCMs), which were collected as part of an international study on microscope quality assessment, were used as a "training" set to build the algorithm. To validate the algorithm and verify its robustness, images from 33 additional microscopes, including LSCM and wide-field (WF) microscopes, were used. The statistical paradigm used for developing the quality scoring scale was a regression approach to supervised learning. Three intensity profiles across each image-2 corner-to-corner diagonals and a center horizontal-were used to generate pixel-intensity data. All of the lines passed through the center of the image. The intensity profile data then were converted into a single-field illumination QF score in the range of 0-100, with 0 having extreme variation, and therefore, essentially unusable, and 100 having no deviation, i.e., straight lines with a constant uniform intensity. Empirically, a QF ≥ 83 was determined to be the minimum acceptable value based on manufacturer acceptance tests and reasonably achievable values. This new QF is an invaluable metric to ascertain objectively and easily the uniformity of illumination quality, provide a traceable reference for monitoring field uniformity over time, and make a direct comparison among different microscopes. The QF can also be used as an indicator of system failure and the need for alignment or service of the instrument. PMID:25802488

  5. A Quantitative Measure of Field Illumination

    PubMed Central

    Brown, Claire M.; Reilly, Andrew

    2015-01-01

    In this paper, we describe a statistically based algorithm to quantify the uniformity of illumination in an optical light microscopy imaging system that outputs a single quality factor (QF) score. The importance of homogeneous field illumination in quantitative light microscopy is well understood and often checked. However, there is currently no standard automatic quantitative measure of the uniformity of the field illumination. Images from 89 different laser-scanning confocal microscopes (LSCMs), which were collected as part of an international study on microscope quality assessment, were used as a “training” set to build the algorithm. To validate the algorithm and verify its robustness, images from 33 additional microscopes, including LSCM and wide-field (WF) microscopes, were used. The statistical paradigm used for developing the quality scoring scale was a regression approach to supervised learning. Three intensity profiles across each image—2 corner-to-corner diagonals and a center horizontal—were used to generate pixel-intensity data. All of the lines passed through the center of the image. The intensity profile data then were converted into a single-field illumination QF score in the range of 0–100, with 0 having extreme variation, and therefore, essentially unusable, and 100 having no deviation, i.e., straight lines with a constant uniform intensity. Empirically, a QF ≥ 83 was determined to be the minimum acceptable value based on manufacturer acceptance tests and reasonably achievable values. This new QF is an invaluable metric to ascertain objectively and easily the uniformity of illumination quality, provide a traceable reference for monitoring field uniformity over time, and make a direct comparison among different microscopes. The QF can also be used as an indicator of system failure and the need for alignment or service of the instrument. PMID:25802488

  6. Simultaneous measurements of on-road/in-vehicle nanoparticles and NOx while driving: Actual situations, passenger exposure and secondary formations.

    PubMed

    Yamada, Hiroyuki; Hayashi, Rumiko; Tonokura, Kenichi

    2016-09-01

    Simultaneous measurements of on-road and in-vehicle NO and NO2 levels, particle number concentrations (PNCs), and particles size distributions were performed while driving using a test vehicle equipped with real-time sensors. The results obtained on regional roads showed that heavy-duty vehicles in traffic seem to have a major impact on on-road air quality. Measurements on highways that included a 10km tunnel and a 2km uphill section of road indicated that sub-50nm particles have different features from the other species because of their higher volatility. The other species showed quite high on-road concentrations in the tunnel. In-vehicle conditions were made similar to the on-road ones by setting the air conditioning (AC) mode to the fresh air mode. The in-vehicle NO2 concentration in the tunnel was over 0.50ppmV, which is almost five times higher than the 1-hour ambient air quality standard proposed by the World Health Organization (WHO). In sections other than the tunnel, the in-vehicle NO2 concentration was almost the same as the 1-hour WHO standard. Higher on-road NO2/NOx ratios than those of exhaust gases and different behavior of sub-50nm particles from other species suggested that NO2 and sub-50nm particles were mainly due to secondary products formed by atmospheric reactions. PMID:26806073

  7. Characterization of differences in calculated and actual measured skin doses to canine limbs during stereotactic radiosurgery using Gafchromic film

    SciTech Connect

    Walters, Jerri; Ryan, Stewart; Harmon, Joseph F.

    2012-07-01

    Accurate calculation of absorbed dose to the skin, especially the superficial and radiosensitive basal cell layer, is difficult for many reasons including, but not limited to, the build-up effect of megavoltage photons, tangential beam effects, mixed energy scatter from support devices, and dose interpolation caused by a finite resolution calculation matrix. Stereotactic body radiotherapy (SBRT) has been developed as an alternative limb salvage treatment option at Colorado State University Veterinary Teaching Hospital for dogs with extremity bone tumors. Optimal dose delivery to the tumor during SBRT treatment can be limited by uncertainty in skin dose calculation. The aim of this study was to characterize the difference between measured and calculated radiation dose by the Varian Eclipse (Varian Medical Systems, Palo Alto, CA) AAA treatment planning algorithm (for 1-mm, 2-mm, and 5-mm calculation voxel dimensions) as a function of distance from the skin surface. The study used Gafchromic EBT film (International Specialty Products, Wayne, NJ), FilmQA analysis software, a limb phantom constructed from plastic water Trade-Mark-Sign (fluke Biomedical, Everett, WA) and a canine cadaver forelimb. The limb phantom was exposed to 6-MV treatments consisting of a single-beam, a pair of parallel opposed beams, and a 7-beam coplanar treatment plan. The canine forelimb was exposed to the 7-beam coplanar plan. Radiation dose to the forelimb skin at the surface and at depths of 1.65 mm and 1.35 mm below the skin surface were also measured with the Gafchromic film. The calculation algorithm estimated the dose well at depths beyond buildup for all calculation voxel sizes. The calculation algorithm underestimated the dose in portions of the buildup region of tissue for all comparisons, with the most significant differences observed in the 5-mm calculation voxel and the least difference in the 1-mm voxel. Results indicate a significant difference between measured and calculated data

  8. A comparison of landing maneuver piloting technique based on measurements made in an airline training simulator and in actual flight

    NASA Technical Reports Server (NTRS)

    Heffley, R. K.; Schulman, T. M.

    1981-01-01

    An emphasis is placed on developing a mathematical model in order to identify useful metrics, quantify piloting technique, and define simulator fidelity. On the basis of DC-10 flight measurements recorded for 32 pilots, 13 flight-trained and the remainder simulator trained, a revised model of the landing flare is hypothesized which accounts for reduction of sink rate and perference for touchdown point along the runway. The flare maneuver and touchdown point adjustment can be described by a pitch attitude command pilot guidance law consisting of altitude and vertical velocity feedbacks. In flight pilots exhibit a significant vertical velocity feedback which is essential for well controlled sink rate reduction at the desired level of response (bandwidth). In the simulator, however, the vertical velocity feedback appears ineffectual and leads to substantially inferior landing performance.

  9. What do stream tracers actually measure? Parameterization of stream transport models with geophysics-based transit time distributions

    NASA Astrophysics Data System (ADS)

    Ward, A. S.

    2013-12-01

    Stream solute tracers are a popular tool to quantify exchanges of water and solutes between the advection-dominated main channel and locations of temporary (commonly "transient") storage. Commonly, in-stream tracer time-series are interpreted with numerical models using assumed residence time distributions for the subsurface because the true distribution cannot be measured. Here, we use time-series analysis of geophysical images of hyporheic solute transport to assess the hyporheic residence time distribution in-situ. This residence time distribution is used to parameterize a numerical model of solute transport and hyporheic exchange. A best-fit is determined by adjusting the maximum observed residence time to consider. In this way, we develop a threshold to differentiate locations in the subsurface that contributed to the in-stream breakthrough curve from those that were beyond the window of detection. Finally, this threshold can be mapped onto the geophysical transect to visualize the physical extent of flowpaths contributing to the in-stream solute breakthrough curve. For the first time, we show the window of detection (a temporal concept) mapped onto a spatial domain.

  10. Characterization of tableting properties measured with a multi-functional compaction instrument for several pharmaceutical excipients and actual tablet formulations.

    PubMed

    Osamura, Takashi; Takeuchi, Yoshiko; Onodera, Risako; Kitamura, Masahiro; Takahashi, Yoshiteru; Tahara, Kohei; Takeuchi, Hirofumi

    2016-08-20

    Before designing tablet formulations, it is important to understand the "Tableting Properties" of excipients and API (active pharmaceutical ingredient) powders. Those properties refer to "Compressibility", "Compactability" and "Manufacturability", which are difficult to evaluate quantitatively. In this study, we aimed to evaluate the "Tableting Properties" by using a benchtop single-punch tablet press, developed recently to measure these parameters using a single device. In order to facilitate understanding of the results visually, we proposed a new plot, where the X-axis showed the tensile fracture stress and the Y-axis showed the ejection stress. This plot, which is composed of four regions, shows the combination of "Compactability" and "Manufacturability". We confirmed the ability of this device to evaluate the characteristics of typical pharmaceutical additives as a value of "Tableting Properties". Losartan potassium was used as an API, and Dilactose R and MCC as an excipient with good "Tableting Properties". The ejection stresses of losartan potassium and Dilactose R were very high. An increase in magnesium stearate shifted the point along the Y-axis in this plot, and it meant an improvement in "Manufacturability". It was confirmed that the device and plot are useful in designing formulations efficiently using a small amount of sample powders. PMID:27184101

  11. A field method for measurement of infiltration

    USGS Publications Warehouse

    Johnson, A.I.

    1963-01-01

    The determination of infiltration--the downward entry of water into a soil (or sediment)--is receiving increasing attention in hydrologic studies because of the need for more quantitative data on all phases of the hydrologic cycle. A measure of infiltration, the infiltration rate, is usually determined in the field by flooding basins or furrows, sprinkling, or measuring water entry from cylinders (infiltrometer rings). Rates determined by ponding in large areas are considered most reliable, but the high cost usually dictates that infiltrometer rings, preferably 2 feet in diameter or larger, be used. The hydrology of subsurface materials is critical in the study of infiltration. The zone controlling the rate of infiltration is usually the least permeable zone. Many other factors affect infiltration rate--the sediment (soil) structure, the condition of the sediment surface, the distribution of soil moisture or soil- moisture tension, the chemical and physical nature of the sediments, the head of applied water, the depth to ground water, the chemical quality and the turbidity of the applied water, the temperature of the water and the sediments, the percentage of entrapped air in the sediments, the atmospheric pressure, the length of time of application of water, the biological activity in the sediments, and the type of equipment or method used. It is concluded that specific values of the infiltration rate for a particular type of sediment are probably nonexistent and that measured rates are primarily for comparative use. A standard field-test method for determining infiltration rates by means of single- or double-ring infiltrometers is described and the construction, installation, and operation of the infiltrometers are discussed in detail.

  12. 3-dimensional strain fields from tomographic measurements

    NASA Astrophysics Data System (ADS)

    Haldrup, K.; Nielsen, S. F.; Mishnaevsky, L., Jr.; Beckmann, F.; Wert, J. A.

    2006-08-01

    Understanding the distributions of strain within solid bodies undergoing plastic deformations has been of interest for many years in a wide range of disciplines, ranging from basic materials science to biology. However, the desire to investigate these strain fields has been frustrated by the inaccessibility of the interior of most samples to detailed investigation without destroying the sample in the process. To some extent, this has been remedied by the development of advanced surface measurement techniques as well as computer models based on Finite Element methods. Over the last decade, this situation has changed by the introduction of a range of tomographic methods based both on advances in computer technology and in instrumentation, advances which have opened up the interior of optically opaque samples for detailed investigations. We present a general method for assessing the strain in the interior of marker-containing specimens undergoing various types of deformation. The results are compared with Finite Element modelling.

  13. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... length of the run. (vi) The actual measuring location is marked exactly on the topographic map, and a... made available, if requested. If a large number of maps is involved, an index map should be submitted... measurements were made, drawn on curved earth paper for equivalent 4/3 earth radius, of the largest...

  14. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... length of the run. (vi) The actual measuring location is marked exactly on the topographic map, and a... involved, an index map should be submitted. (iii) All information necessary to determine the pertinent... in each direction in which measurements were made, drawn on curved earth paper for equivalent...

  15. Solar Polarimetry and Magnetic Field Measurements

    NASA Astrophysics Data System (ADS)

    del Toro Iniesta, J. C.

    2001-05-01

    The magnetic nature of most solar (spatially resolved or unresolved) structures is amply recognized. Magnetic fields of the Sun play a paramount rôle in the overall thermodynamic and dynamic state of our star. The main observable manifestation of solar magnetic fields is the polarization of light either through the Zeeman effect on spectral lines or through the Hanle effect (depolarization by very weak magnetic fields of light previously polarized by scattering). Hence, one can easily understand the increasing importance that polarimetry is experimenting continuously in solar physics. Under the title of this contribution a six-hour course was given during the summer school. Clearly, the limited extension allocated for the notes in these proceedings avoids an extensive account of the several topics discussed: 1) a description of light as an electromagnetic wave and the polarization properties of monochromatic, time-harmonic, plane waves; 2) the polarization properties of polychromatic light and, in particular, of quasi-monochromatic light; 3) the transformations of (partially) polarized light by linear optical systems and a description of the ways we measure the Stokes parameters by spatially and/or temporally modulating the polarimetric signal; 4) a discussion on specific problems relevant to solar polarimetry like seeing-induced and instrumental polarization, or modulation and demodulation, along with a brief description of current solar polarimeters; 5) the vector radiative transfer equation for polarized light and its links to the scalar one for unpolarized light, together with a summary of the Zeeman effect and its consequences on line formation in a magnetized stellar atmosphere; 7) an introduction of the paramount astrophysical problem, i.e., that of finding diagnostics that enable the solar physicist to interpret the observables in terms of the solar atmospheric quantities, including a discussion on contribution and response functions; and 8) a brief

  16. Polarization bispectrum for measuring primordial magnetic fields

    SciTech Connect

    Shiraishi, Maresuke

    2013-11-01

    We examine the potential of polarization bispectra of the cosmic microwave background (CMB) to constrain primordial magnetic fields (PMFs). We compute all possible bispectra between temperature and polarization anisotropies sourced by PMFs and show that they are weakly correlated with well-known local-type and secondary ISW-lensing bispectra. From a Fisher analysis it is found that, owing to E-mode bispectra, in a cosmic-variance-limited experiment the expected uncertainty in the amplitude of magnetized bispectra is 80% improved in comparison with an analysis in terms of temperature auto-bispectrum alone. In the Planck or the proposed PRISM experiment cases, we will be able to measure PMFs with strength 2.6 or 2.2 nG. PMFs also generate bispectra involving B-mode polarization, due to tensor-mode dependence. We also find that the B-mode bispectrum can reduce the uncertainty more drastically and hence PMFs comparable to or less than 1 nG may be measured in a PRISM-like experiment.

  17. Wind Field Measurements With Airborne Doppler Lidar

    NASA Technical Reports Server (NTRS)

    Menzies, Robert T.

    1999-01-01

    In collaboration with lidar atmospheric remote sensing groups at NASA Marshall Space Flight Center and National Oceanic and Atmospheric Administration (NOAA) Environmental Technology Laboratory, we have developed and flown the Multi-center Airborne Coherent Atmospheric Wind Sensor (MACAWS) lidar on the NASA DC-8 research aircraft. The scientific motivations for this effort are: to obtain measurements of subgrid scale (i.e. 2-200 km) processes and features which may be used to improve parameterizations in global/regional-scale models; to improve understanding and predictive capabilities on the mesoscale; and to assess the performance of Earth-orbiting Doppler lidar for global tropospheric wind measurements. MACAWS is a scanning Doppler lidar using a pulsed transmitter and coherent detection; the use of the scanner allows 3-D wind fields to be produced from the data. The instrument can also be radiometrically calibrated and used to study aerosol, cloud, and surface scattering characteristics at the lidar wavelength in the thermal infrared. MACAWS was used to study surface winds off the California coast near Point Arena, with an example depicted in the figure below. The northerly flow here is due to the Pacific subtropical high. The coastal topography interacts with the northerly flow in the marine inversion layer, and when the flow passes a cape or point that juts into the winds, structures called "hydraulic expansion fans" are observed. These are marked by strong variation along the vertical and cross-shore directions. The plots below show three horizontal slices at different heights above sea level (ASL). Bottom plots are enlargements of the area marked by dotted boxes above. The terrain contours are in 200-m increments, with the white spots being above 600-m elevation. Additional information is contained in the original.

  18. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... where the field strength is being measured for a building taller than one-story, elevate the testing...) above the ground. In situations where the field strength is being measured for a building taller...

  19. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... where the field strength is being measured for a building taller than one-story, elevate the testing...) above the ground. In situations where the field strengthis being measured for a building taller than...

  20. Field methods for measuring concentrated flow erosion

    NASA Astrophysics Data System (ADS)

    Castillo, C.; Pérez, R.; James, M. R.; Quinton, J. N.; Taguas, E. V.; Gómez, J. A.

    2012-04-01

    Many studies have stressed the importance of gully erosion in the overall soil loss and sediment yield of agricultural catchments, for instance in recent years (Vandaele and Poesen, 1995; De Santisteban et al., 2006; Wu el al, 2008). Several techniques have been used for determining gully erosion in field studies. The conventional techniques involved the use of different devices (i.e. ruler, pole, tape, micro-topographic profilers, total station) to calculate rill and gully volumes through the determination of cross sectional areas and length of reaches (Casalí et al, 1999; Hessel and van Asch, 2003). Optical devices (i.e. laser profilemeters) have also been designed for the purpose of rapid and detailed assessment of cross sectional areas in gully networks (Giménez et al., 2009). These conventional 2d methods provide a simple and un-expensive approach for erosion evaluation, but are time consuming to carry out if a good accuracy is required. On the other hand, remote sensing techniques are being increasingly applied to gully erosion investigation such as aerial photography used for big-scale, long-term, investigations (e.g. Martínez-Casasnovas et al., 2004; Ionita, 2006), airborne and terrestrial LiDAR datasets for gully volume evaluation (James et al., 2007; Evans and Lindsay, 2010) and recently, major advances in 3D photo-reconstruction techniques (Welty et al. 2010, James et al., 2011). Despite its interest, few studies simultaneously compare the accuracies of the range of conventional and remote sensing techniques used, or define the most suitable method for a particular scale, given and time and cost constraints. That was the reason behind the International Workshop Innovations in the evaluation and measurement of rill and gully erosion, held in Cordoba in May 2011 and from which derive part of the materials presented in this abstract. The main aim of this work was to compare the accuracy and time requirements of traditional (2D) and recently developed

  1. Unreliability of global temperature trends: the circular logic of comparing models with models or with models inspired reconstructions to circumvent lack of validation versus actual measurements

    NASA Astrophysics Data System (ADS)

    Parker, A.; Ollier, C. D.

    2015-12-01

    This recent paper by Marotzke and Forster [1] has received media attention because it claims to have shown that the recent pause in surface temperature rise was the result of natural variability, and that climate models are not systematically overestimating the global warming. Nicholas Lewis [2] has already commented about the serious statistical errors in the paper that make the conclusion unsustainable.We note here that their supporting evidence is actually alteration of pre-selected data to sustain the global warming narrative. The "observed trends" of Marotzke and Forster are not based on the truly measured temperatures in every world gridded cell of the land and sea since the 1860s, but only on a reconstruction based on selected, scattered data that are continuously recalculated to resemble the climate model outputs.

  2. Sample taking problems in measuring actual histamine levels of human gastroduodenal mucosa: specific and general relevance in clinical trials on peptic ulcer pathogenesis and selective proximal vagotomy.

    PubMed Central

    Thon, K P; Lorenz, W; Ohmann, C; Weber, D; Rohde, H; Röher, H D

    1985-01-01

    Changes in histamine storage in the oxyntic mucosa of duodenal ulcer patients and their reversal by vagotomy and the histamine H2-antagonist cimetidine supported the hypothesis that histamine could be a causal factor in peptic ulcer pathogenesis. The specificity of these findings was impaired by problems in biopsy taking, however, and in the preparative steps before measuring the actual histamine contents in all parts of the gastric mucosa and in the duodenum. A prospective trial was carried out in 190 patients to identify these sources of bias and to overcome them by appropriate study designs. Usually a direct correlation was found between weight of biopsy and mucosal histamine content. This problem was solved by selecting a biopsy forceps producing smaller variations in sample size, by limiting the time of cold ischaemia to four to five minutes only and by taking three biopsy specimens for each single histamine value. The actual histamine content of mucosal biopsies remained constant for about four to five minutes only. The 'disappearance' rate was faster in control subjects than in duodenal ulcer patients. Hence by variation of the cold ischaemia time any artefacts of differences between mucosal histamine levels in controls and duodenal ulcer patients could be produced. Using the optimised sample taking procedure mucosal histamine contents of several gastric regions and the duodenal bulb were measured in 24 patients with duodenal ulcer, after selective proximal vagotomy without drainage and in control subjects without any stomach disease (randomised controlled trial). The histamine content was lower in all parts of the upper gastrointestinal tract in duodenal ulcer patients than in controls and was raised again in all regions after selective proximal vagotomy. As the most likely hypothesis it is suggested that vagal reflexes with afferent fibres coming from the oxyntic mucosa stimulate histamine release in duodenal ulcer patients by efferent peptidergic neurones

  3. Performance changes and relationship between vertical jump measures and actual sprint performance in elite sprinters with visual impairment throughout a Parapan American games training season

    PubMed Central

    Loturco, Irineu; Winckler, Ciro; Kobal, Ronaldo; Cal Abad, Cesar C.; Kitamura, Katia; Veríssimo, Amaury W.; Pereira, Lucas A.; Nakamura, Fábio Y.

    2015-01-01

    The aims of this study were to estimate the magnitude of variability and progression in actual competitive and field vertical jump test performances in elite Paralympic sprinters with visual impairment in the year leading up to the 2015 Parapan American Games, and to investigate the relationships between loaded and unloaded vertical jumping test results and actual competitive sprinting performance. Fifteen Brazilian Paralympic sprinters with visual impairment attended seven official competitions (four national, two international and the Parapan American Games 2015) between April 2014 and August 2015, in the 100- and 200-m dash. In addition, they were tested in five different periods using loaded (mean propulsive power [MPP] in jump squat [JS] exercise) and unloaded (squat jump [SJ] height) vertical jumps within the 3 weeks immediately prior to the main competitions. The smallest important effect on performances was calculated as half of the within-athlete race-to-race (or test-to-test) variability and a multiple regression analysis was performed to predict the 100- and 200-m dash performances using the vertical jump test results. Competitive performance was enhanced during the Parapan American Games in comparison to the previous competition averages, overcoming the smallest worthwhile enhancement in both the 100- (0.9%) and 200-m dash (1.43%). In addition, The SJ and JS explained 66% of the performance variance in the competitive results. This study showed that vertical jump tests, in loaded and unloaded conditions, could be good predictors of the athletes' sprinting performance, and that during the Parapan American Games the Brazilian team reached its peak competitive performance. PMID:26594181

  4. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Field strength measurements. 73.314 Section 73... BROADCAST SERVICES FM Broadcast Stations § 73.314 Field strength measurements. (a) Except as provided for in... concerning the amendment of such technical standards. Persons making field strength measurements for...

  5. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 47 Telecommunication 4 2012-10-01 2012-10-01 false Field strength measurements. 73.314 Section 73... BROADCAST SERVICES FM Broadcast Stations § 73.314 Field strength measurements. (a) Except as provided for in... concerning the amendment of such technical standards. Persons making field strength measurements for...

  6. Field Emission Measurements from Niobium Electrodes

    SciTech Connect

    M. BastaniNejad, P.A. Adderley, J. Clark, S. Covert, J. Hansknecht, C. Hernandez-Garcia, R. Mammei, M. Poelker

    2011-03-01

    Increasing the operating voltage of a DC high voltage photogun serves to minimize space charge induced emittance growth and thereby preserve electron beam brightness, however, field emission from the photogun cathode electrode can pose significant problems: constant low level field emission degrades vacuum via electron stimulated desorption which in turn reduces photocathode yield through chemical poisoning and/or ion bombardment and high levels of field emission can damage the ceramic insulator. Niobium electrodes (single crystal, large grain and fine grain) were characterized using a DC high voltage field emission test stand at maximum voltage -225kV and electric field gradient > 10MV/m. Niobium electrodes appear to be superior to diamond-paste polished stainless steel electrodes.

  7. Determination of the far-field from measured near-field data, theory and measuring technique of the near-field far-field transformation

    NASA Astrophysics Data System (ADS)

    Schrott, A.; Stein, V.

    1980-12-01

    Methods are described for measuring the far field of antennas at distances that are small compared to the wavelength of the field. The so called compact test range is explained and the principle of the near field far field transformation is described. The advantages and disadvantages of the planar, cylindrical, and spherical transformation techniques are discussed. Theory and measuring technique for the spherical method are treated extensively. An assessment of the influence of errors is given and the acceptable tolerances are presented. A proposal is given for the construction of a near field test range. Finally the performance of the method is demonstrated with the aid of some examples.

  8. Atomic-position resolution by quadrature-field measurement

    NASA Astrophysics Data System (ADS)

    Storey, Pippa; Collett, Matthew; Walls, Daniel

    1993-01-01

    An atom passing through a standing light field imparts a position-dependent phase shift to the field. By making a phase-sensitive measurement of the field, it is possible to resolve the atom's position to much less than the wavelength of the light. The field measurement results in the creation of virtual slits, and diffraction and interference phenomena may be observed. The phase measurements give welcher Weg information and enable ``quantum-eraser'' experiments to be realized.

  9. The role of visual perception measures used in sports vision programmes in predicting actual game performance in Division I collegiate hockey players.

    PubMed

    Poltavski, Dmitri; Biberdorf, David

    2015-01-01

    Abstract In the growing field of sports vision little is still known about unique attributes of visual processing in ice hockey and what role visual processing plays in the overall athlete's performance. In the present study we evaluated whether visual, perceptual and cognitive/motor variables collected using the Nike SPARQ Sensory Training Station have significant relevance to the real game statistics of 38 Division I collegiate male and female hockey players. The results demonstrated that 69% of variance in the goals made by forwards in 2011-2013 could be predicted by their faster reaction time to a visual stimulus, better visual memory, better visual discrimination and a faster ability to shift focus between near and far objects. Approximately 33% of variance in game points was significantly related to better discrimination among competing visual stimuli. In addition, reaction time to a visual stimulus as well as stereoptic quickness significantly accounted for 24% of variance in the mean duration of the player's penalty time. This is one of the first studies to show that some of the visual skills that state-of-the-art generalised sports vision programmes are purported to target may indeed be important for hockey players' actual performance on the ice. PMID:25142869

  10. First Viking results - Magnetic field measurements

    NASA Technical Reports Server (NTRS)

    Potemra, T. A.; Zanetti, L. J.; Erlandson, R. E.; Gustafsson, G.; Acuna, M. H.

    1988-01-01

    The magnetic field experiment on the Swedish Viking satellite consists of a triaxial fluxgate magnetometer system with the sensors mounted on a 2-m boom. Transverse magnetic field perturbations are readily observed which identify the large-scale auroral and cusp-region Birkeland current (BC) systems. A sharp gradient was observed in the dayside region near apogee and 08:40 MLT during a pass on March 25, 1986 which has been interpreted as an earthward-flowing BC of 8 micro-A/sq m. When projected to ionospheric altitudes it is estimated that the current density is 200 micro-A/sq m.

  11. Deducing dust emission mechanisms from field measurements

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Field observations are needed to both develop and test theories on dust emission for use in global modeling systems. The mechanism of dust emission (aerodynamic entrainment, saltation bombardment, aggregate disintegration) and the amount and particle-size distribution of emitted dust may vary under ...

  12. Measuring Soil Nitrogen Mineralization under Field Conditions

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Land application of animal manure is known to alter rates of nitrogen (N) mineralization in soils, but quantitative information concerning intensity and duration of these effects has been difficult to obtain under field conditions. We estimated net effects of manure on N mineralization in soils unde...

  13. Calorimetric method of ac loss measurement in a rotating magnetic field.

    PubMed

    Ghoshal, P K; Coombs, T A; Campbell, A M

    2010-07-01

    A method is described for calorimetric ac-loss measurements of high-T(c) superconductors (HTS) at 80 K. It is based on a technique used at 4.2 K for conventional superconducting wires that allows an easy loss measurement in parallel or perpendicular external field orientation. This paper focuses on ac loss measurement setup and calibration in a rotating magnetic field. This experimental setup is to demonstrate measuring loss using a temperature rise method under the influence of a rotating magnetic field. The slight temperature increase of the sample in an ac-field is used as a measure of losses. The aim is to simulate the loss in rotating machines using HTS. This is a unique technique to measure total ac loss in HTS at power frequencies. The sample is mounted on to a cold finger extended from a liquid nitrogen heat exchanger (HEX). The thermal insulation between the HEX and sample is provided by a material of low thermal conductivity, and low eddy current heating sample holder in vacuum vessel. A temperature sensor and noninductive heater have been incorporated in the sample holder allowing a rapid sample change. The main part of the data is obtained in the calorimetric measurement is used for calibration. The focus is on the accuracy and calibrations required to predict the actual ac losses in HTS. This setup has the advantage of being able to measure the total ac loss under the influence of a continuous moving field as experienced by any rotating machines. PMID:20687748

  14. Calorimetric method of ac loss measurement in a rotating magnetic field

    NASA Astrophysics Data System (ADS)

    Ghoshal, P. K.; Coombs, T. A.; Campbell, A. M.

    2010-07-01

    A method is described for calorimetric ac-loss measurements of high-Tc superconductors (HTS) at 80 K. It is based on a technique used at 4.2 K for conventional superconducting wires that allows an easy loss measurement in parallel or perpendicular external field orientation. This paper focuses on ac loss measurement setup and calibration in a rotating magnetic field. This experimental setup is to demonstrate measuring loss using a temperature rise method under the influence of a rotating magnetic field. The slight temperature increase of the sample in an ac-field is used as a measure of losses. The aim is to simulate the loss in rotating machines using HTS. This is a unique technique to measure total ac loss in HTS at power frequencies. The sample is mounted on to a cold finger extended from a liquid nitrogen heat exchanger (HEX). The thermal insulation between the HEX and sample is provided by a material of low thermal conductivity, and low eddy current heating sample holder in vacuum vessel. A temperature sensor and noninductive heater have been incorporated in the sample holder allowing a rapid sample change. The main part of the data is obtained in the calorimetric measurement is used for calibration. The focus is on the accuracy and calibrations required to predict the actual ac losses in HTS. This setup has the advantage of being able to measure the total ac loss under the influence of a continuous moving field as experienced by any rotating machines.

  15. Calorimetric method of ac loss measurement in a rotating magnetic field

    SciTech Connect

    Ghoshal, P. K.; Coombs, T. A.; Campbell, A. M.

    2010-07-15

    A method is described for calorimetric ac-loss measurements of high-T{sub c} superconductors (HTS) at 80 K. It is based on a technique used at 4.2 K for conventional superconducting wires that allows an easy loss measurement in parallel or perpendicular external field orientation. This paper focuses on ac loss measurement setup and calibration in a rotating magnetic field. This experimental setup is to demonstrate measuring loss using a temperature rise method under the influence of a rotating magnetic field. The slight temperature increase of the sample in an ac-field is used as a measure of losses. The aim is to simulate the loss in rotating machines using HTS. This is a unique technique to measure total ac loss in HTS at power frequencies. The sample is mounted on to a cold finger extended from a liquid nitrogen heat exchanger (HEX). The thermal insulation between the HEX and sample is provided by a material of low thermal conductivity, and low eddy current heating sample holder in vacuum vessel. A temperature sensor and noninductive heater have been incorporated in the sample holder allowing a rapid sample change. The main part of the data is obtained in the calorimetric measurement is used for calibration. The focus is on the accuracy and calibrations required to predict the actual ac losses in HTS. This setup has the advantage of being able to measure the total ac loss under the influence of a continuous moving field as experienced by any rotating machines.

  16. Rocket borne instrument to measure electric fields inside electrified clouds

    NASA Technical Reports Server (NTRS)

    Ruhnke, L. H.

    1973-01-01

    Simple electric field measuring system is mounted on small rocket and consists of two voltage probes, one extending from nose and other on tail fin. Electric field through which rocket passes is determined by potential difference between probes.

  17. Measurements of vector fields with diode array

    NASA Technical Reports Server (NTRS)

    Wiehr, E. J.; Scholiers, W.

    1985-01-01

    A polarimeter was designed for high spatial and spectral resolution. It consists of a quarter-wave plate alternately operating in two positions for Stoke-V measurements and an additional quarter-wave plate for Stokes-U and -Q measurements. The spatial range covers 75 arcsec, the spectral window of about 1.8 a allows the simultaneous observations of neighboring lines. The block diagram of the data processing and acquisition system consists of five memories each one having a capacity of 10 to the 4th power 16-bit words. The total time to acquire profiles of Stokes parameters can be chosen by selecting the number of successive measurements added in the memories, each individual measurement corresponding to an integration time of 0.5 sec. Typical values range between 2 and 60 sec depending on the brightness of the structure, the amount of polarization and a compromise between desired signal-to-noise ratio and spatial resolution.

  18. Field Measurement of the Acoustic Nonlinearity Parameter in Turbine Blades

    NASA Technical Reports Server (NTRS)

    Hinton, Yolanda L.; Na, Jeong K.; Yost, William T.; Kessel, Gregory L.

    2000-01-01

    Nonlinear acoustics techniques were used to measure fatigue in turbine blades in a power generation plant. The measurements were made in the field using a reference based measurement technique, and a reference sample previously measured in the laboratory. The acoustic nonlinearity parameter showed significant increase with fatigue in the blades, as indicated by service age and areas of increased stress. The technique shows promise for effectively measuring fatigue in field applications and predicting subsequent failures.

  19. Earth's Magnetic Field Measurements for the LCLS Undulators

    SciTech Connect

    Hacker, Kirsten

    2010-12-13

    Measurements of the earth's magnetic field at several locations at SLAC were conducted to determine the possible field error contribution from tuning the undulators in a location with a different magnetic field than that which will be found in the undulator hall. An average difference of 0.08 {+-} 0.04 Gauss has been measured between the downward earth's field components in the test facility and SLAC tunnel locations.

  20. Laboratory Measurements of Astrophysical Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Murphy, C. D.; Miniati, F.; Edwards, M.; Mithen, J.; Bell, A. R.; Constantin, C.; Everson, E.; Schaeffer, D.; Niemann, C.; Ravasio, A.; Brambrink, E.; Benuzzi-Mounaix, A.; Koenig, M.; Gregory, C.; Woolsey, N.; Park, H.-S.; Remington, B.; Ryutov, D.; Bingham, R.; Gargate, L.; Spitkovsky, A.; Gregori, G.

    2010-11-01

    It has been proposed that high Mach number collisionless shocks propagating in an initially unmagnetized plasma play a major role in the magnetization of large scale structures in the Universe. A detailed study of the experimental configuration necessary to scale such environments down to laboratory dimensions will be presented. We will show initial results from preliminary experiments conducted at the Phoenix laser (UCLA) and the LULI laser (Ecole Polytechnique) where collisionless shocks are generated by the expansion of exploding foils driven by energetic laser beams. The time evolution of the magnetic field is probed with induction coils placed at 10 cm from the laser focus. We will discuss various mechanisms of magnetic field generation and compare them with the experimental results.

  1. Far-field patterns of spaceborne antennas from plane-polar near-field measurements

    NASA Technical Reports Server (NTRS)

    Rahmat-Samii, Y.; Gatti, M. S.

    1985-01-01

    Certain unique features of a recently constructed plane-polar near-field measurement facility for determining the far-field patterns of large and fragile spaceborne antennas are described. In this facility, the horizontally positioned antenna rotates about its axis while the measuring probe is advanced incrementally in a fixed radial direction. The near-field measured data is then processed using a Jacobi-Bessel expansion to obtain the antenna far fields. A summary of the measurement and computational steps is given. Comparisons between the outdoor far-field measurements and the constructed far-field patterns from the near-field measured data are provided for different antenna sizes and frequencies. Application of the substitution method for the absolute gain measurement is discussed. In particular, results are shown for the 4.8-m mesh-deployable high-gain antenna of the Galileo spacecraft which has the mission of orbiting Jupiter in 1988.

  2. Measuring electric fields from surface contaminants with neutral atoms

    SciTech Connect

    Obrecht, J. M.; Wild, R. J.; Cornell, E. A.

    2007-06-15

    In this paper we demonstrate a technique of utilizing magnetically trapped neutral {sup 87}Rb atoms to measure the magnitude and direction of stray electric fields emanating from surface contaminants. We apply an alternating external electric field that adds to (or subtracts from) the stray field in such a way as to resonantly drive the trapped atoms into a mechanical dipole oscillation. The growth rate of the oscillation's amplitude provides information about the magnitude and sign of the stray field gradient. Using this measurement technique, we are able to reconstruct the vector electric field produced by surface contaminants. In addition, we can accurately measure the electric fields generated from adsorbed atoms purposely placed onto the surface and account for their systematic effects, which can plague a precision surface-force measurement. We show that baking the substrate can reduce the electric fields emanating from adsorbate and that the mechanism for reduction is likely surface diffusion, not desorption.

  3. A new probe for measuring small electric fields in plasmas

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.

    1991-01-01

    A dipolar double probe has been developed for in situ measurements of small electric fields in laboratory plasmas. The probe measures dc to ac electric fields (f values between 0 and 20 MHz) with high sensitivity (Emin about 10 microV/cm) and responds to both space charge electric fields and inductive electric fields. Using voltage-to-frequency conversion, the probe signal is obtained free of errors and loading effects by a transmission line. Various examples of useful applications for the new probe are presented, such as measurements of dc ambipolar fields, ac space-charge fields of ion acoustic waves, ac inductive fields of whistler waves, and mixed inductive and space-charge electric fields in current-carrying magnetoplasmas.

  4. Evaluation of measurement reproducibility using the standard-sites data, 1994 Fernald field characterization demonstration project

    SciTech Connect

    Rautman, C.A.

    1996-02-01

    The US Department of Energy conducted the 1994 Fernald (Ohio) field characterization demonstration project to evaluate the performance of a group of both industry-standard and proposed alternative technologies in describing the nature and extent of uranium contamination in surficial soils. Detector stability and measurement reproducibility under actual operating conditions encountered in the field is critical to establishing the credibility of the proposed alternative characterization methods. Comparability of measured uranium activities to those reported by conventional, US Environmental Protection Agency (EPA)-certified laboratory methods is also required. The eleven (11) technologies demonstrated included (1) EPA-standard soil sampling and laboratory mass-spectroscopy analyses, and currently-accepted field-screening techniques using (2) sodium-iodide scintillometers, (3) FIDLER low-energy scintillometers, and (4) a field-portable x-ray fluorescence spectrometer. Proposed advanced characterization techniques included (5) alpha-track detectors, (6) a high-energy beta scintillometer, (7) electret ionization chambers, (8) and (9) a high-resolution gamma-ray spectrometer in two different configurations, (10) a field-adapted laser ablation-inductively coupled plasma-atomic emission spectroscopy (ICP-AES) technique, and (11) a long-range alpha detector. Measurement reproducibility and the accuracy of each method were tested by acquiring numerous replicate measurements of total uranium activity at each of two ``standard sites`` located within the main field demonstration area. Meteorological variables including temperature, relative humidity. and 24-hour rainfall quantities were also recorded in conjunction with the standard-sites measurements.

  5. Impeller flow field measurement and analysis

    NASA Technical Reports Server (NTRS)

    Fagan, J. R.; Fleeter, S.

    1991-01-01

    A series of experiments are performed to investigate and quantify the three-dimensional mean flow field in centrifugal compressor flow passages and to evaluate contemporary internal flow models. The experiments include the acquisition and analysis of LDV data in the impeller passages of a low-speed moderate-scale research mixed-flow centrifugal compressor operating at its design point. Predictions from a viscous internal flow model are then correlated with these data. The LDV data show the traditional jet-wake structure observed in many centrifugal compressors, with the wake observed along the shroud 70 percent of the length from the pressure to suction surface. The viscous model predicts the major flow phenomena. However, the correlations of the viscous predictions with the LDV data were poor.

  6. Magnetic Measurement of the Background Field in the Undulator Hall

    SciTech Connect

    Fisher, Andrew; Nuhn, Heinz-Dieter; Welch, James; /SLAC

    2010-11-18

    The steel present in the construction of the undulator hall facility has the potential for changing the ambient fields present in the undulator hall. This note describes a measurement done to make a comparison between the fields in the hall and in the Magnetic Measurement Facility. In order for the undulators to have the proper tuning, the background magnetic field in the Undulator Hall should agree with the background field in the Magnetic Measurements Facility within .5 gauss. In order to verify that this was the case measurements were taken along the length of the undulator hall, and the point measurements were compared to the mean field which was measured on the MMF test bench.

  7. Measurement and Analysis of Field Emission Electrons in the LCLS Gun

    SciTech Connect

    Dowell, D.H.; Jongewaard, E.; Limborg-Deprey, C.; Schmerge, J.F.; Vlieks, A.; /SLAC

    2007-11-02

    The field emission was measured during the high-power testing of the LCLS photocathode RF gun. A careful study and analysis of the field emission electrons, or dark current is important in assessing the gun's internal surface quality in actual operation, especially those surfaces with high fields. The first indication of a good RF gun design and fabrication is short processing time to the required fields and low electron emission at high fields. The charge per 2 microsecond long RF pulse (the dark charge) was measured as a function of the peak cathode field for the 1.6 cell, 2.856GHz LCLS RF gun. Faraday cup data was taken for cathode peak RF fields up to 120MV/m producing a maximum of 0.6nC/RF pulse for a diamond-turned polycrystalline copper cathode installed in the gun. Digitized images of the dark charge were taken using a 100 micron thick YAG crystal for a range of solenoid fields to determine the location and angular distribution of the field emitters. The FN plots and emitter image analysis will be described in this paper.

  8. A dipole probe for electric field measurements in the LVPD

    NASA Astrophysics Data System (ADS)

    Srivastava, P. K.; Awasthi, L. M.; Ravi, G.; Kumar, Sunil; Mattoo, S. K.

    2016-01-01

    This paper describes the design, construction, and calibration of an electric dipole probe and demonstrates its capability by presenting results on the measurement of electric field excited by a ring electrode in the Large Volume Plasma Device (LVPD). It measures the electric field in vacuum and plasma conditions in a frequency range lying between 1-10 \\text{MHz} . The results show that it measures electric field ≥slant 2 mV cm-1 for frequency ≤slant 10 \\text{MHz} . The developed dipole probe works on the principle of amplitude modulation. The probe signal is transmitted through a carrier of 418 MHz, a much higher frequency than the available sources of noise present in the surrounding environment. The amplitude modulation concept of signal transmission is used to make the measurement; it is qualitatively better and less corrupted as it is not affected by the errors introduced by ac pickups. The probe is capable of measuring a variety of electric fields, namely (1) space charge field, (2) time varying field, (3) inductive field and (4) a mixed field containing both space charge and inductive fields. This makes it a useful tool for measuring electric fields in laboratory plasma devices.

  9. Brief: Field measurements of casing tension forces

    SciTech Connect

    Quigley, M.S.; Lewis, D.B.; Boswell, R.S.

    1995-02-01

    Tension forces acting on individual casing joints were accurately measured during installation of 10,158 ft of 9 5/8-in. {times} 47-lbm/ft casing and 11,960 ft of 11 7/8-in. {times} 71.8-lbm/ft casing. A unique casing load table (CLT) weighed the casing string after the addition of each casing joint. Strain gauges attached inside the pin ends of instrumented casing joints (ICJ`s) directly measured tension force on those joints. A high-speed computer data-acquisition system (DAS) automatically recorded data from all the sensors. Several casing joints were intentionally subjected to extreme deceleration to determine upper limits for dynamic tension forces. Data from these tests clearly show effects of wellbore friction and casing handling conditions. In every case, tension forces in the casing during maximum deceleration were considerably less than expected. In some cases, the highest tension forces occurred when the casing lifted out of the slips. Peak tension forces caused by setting the casing slips were typically no more than 5% greater than tension forces in the casing at rest. This dynamic amplification was far less than the 60% value used in the previous casing design method. Reducing the safety factor for installation loads has permitted use of lighter, less-expensive casing than dictated by older design criteria.

  10. Measuring the Earth's Magnetic Field in a Laboratory

    ERIC Educational Resources Information Center

    Cartacci, A.; Straulino, S.

    2008-01-01

    Two methods for measuring the Earth's magnetic field are described. In the former, according to Gauss, the Earth's magnetic field is compared with that of a permanent magnet; in the latter, a well-known method, the comparison is made with the magnetic field generated by a current. As all the used instruments are available off the shelf, both…

  11. Magnetic field measurements via visible spectroscopy on the Z machine.

    PubMed

    Gomez, M R; Hansen, S B; Peterson, K J; Bliss, D E; Carlson, A L; Lamppa, D C; Schroen, D G; Rochau, G A

    2014-11-01

    Sandia's Z Machine uses its high current to magnetically implode targets relevant to inertial confinement fusion. Since target performance is highly dependent on the applied drive field, measuring magnetic field at the target is essential for accurate simulations. Recently, the magnetic field at the target was measured through splitting of the sodium 3s-3p doublet at 5890 and 5896 Å. Spectroscopic dopants were applied to the exterior of the target, and spectral lines were observed in absorption. Magnetic fields in excess of 200 T were measured, corresponding to drive currents of approximately 5 MA early in the pulse. PMID:25430355

  12. Magnetic field measurements via visible spectroscopy on the Z machine

    SciTech Connect

    Gomez, M. R. Hansen, S. B.; Peterson, K. J.; Bliss, D. E.; Carlson, A. L.; Lamppa, D. C.; Rochau, G. A.; Schroen, D. G.

    2014-11-15

    Sandia's Z Machine uses its high current to magnetically implode targets relevant to inertial confinement fusion. Since target performance is highly dependent on the applied drive field, measuring magnetic field at the target is essential for accurate simulations. Recently, the magnetic field at the target was measured through splitting of the sodium 3s-3p doublet at 5890 and 5896 Å. Spectroscopic dopants were applied to the exterior of the target, and spectral lines were observed in absorption. Magnetic fields in excess of 200 T were measured, corresponding to drive currents of approximately 5 MA early in the pulse.

  13. On the measurement of stationary electric fields in air

    NASA Technical Reports Server (NTRS)

    Kirkham, H.

    2002-01-01

    Applications and measurement methods for field measurements are reviewed. Recent developments using optical technology are examined. The various methods are compared. It is concluded that the best general purpose instrument is the isolated cylindrical field mill, but MEMS technology could furnish better instruments in the future.

  14. Molecular-scale measurements of electric fields at electrochemical interfaces.

    SciTech Connect

    Hayden, Carl C.; Farrow, Roger L.

    2011-01-01

    Spatially resolved measurements of electric fields at electrochemical interfaces would be a critical step toward further understanding and modeling the detailed structure of electric double layers. The goal of this project was to perform proof-of-principle experiments to demonstrate the use of field-sensitive dyes for optical measurements of fields in electrochemical systems. A confocal microscope was developed that provides sensitive detection of the lifetime and high resolution spectra of excited fluorescence for dyes tethered to electrically conductive surfaces. Excited state lifetimes for the dyes were measured and found to be relatively unquenched when linked to indium tin oxide, but strongly quenched on gold surfaces. However, our fluorescence detection is sufficiently sensitive to measure spectra of submonolayer dye coatings even when the fluorescence was strongly quenched. Further work to create dye labeled interfaces on flat, uniform and durable substrates is necessary to make electric field measurements at interfaces using field sensitive dyes.

  15. Evaluating the performance of reference evapotranspiration equations with scintillometer measurements under Mediterranean climate and effects on olive grove actual evapotranspiration estimated with FAO-56 water balance model

    NASA Astrophysics Data System (ADS)

    Minacapilli, Mario; Cammalleri, Carmelo; Ciraolo, Giuseppe; Provenzano, Giuseppe; Rallo, Giovanni

    2014-05-01

    The concept of reference evapotranspiration (ETo) is widely used to support water resource management in agriculture and for irrigation scheduling, especially under arid and semi-arid conditions. The Penman-Monteith standardized formulations, as suggested by ASCE and FAO-56 papers, are generally applied for accurate estimations of ETo, at hourly and daily scale. When detailed meteorological information are not available, several alternative and simplified equations, using a limited number of variables, have been proposed (Blaney-Criddle, Hargreaves-Samani, Turc, Makkinen and Pristley-Taylor). In this paper, scintillometer measurements collected for six month in 2005, on an experimental plot under "reference" conditions, were used to validate different ETo equations at hourly and daily scale. Experimental plot is located in a typical agricultural Mediterranean environment (Sicily, Italy), where olive groves is the dominant crop. As proved by other researches, the comparison confirmed the best agreement between estimated and measured fluxes corresponds to FAO-56 Penman-Monteith standardized equation, that was characterized by both the lowest average error and the minimum bias. However, the analysis also evidenced a quite good performance of Pristley-Taylor equation, that can be considered as a valid alternative to the more sophisticated Penman-Monteith method. The different ETo series, obtained by the considered simplified equations, were then used as input in the FAO-56 water balance model, in order to evaluate, for olive groves, the errors on estimated actual evapotranspiration ET. To this aim soil and crop model input parameters were settled by considering previous experimental researches already used to calibrate and validate the FAO-56 water balance model on olive groves, for the same study area. Also in this case, assuming as the true values of ET those obtained using the water balance coupled with Penman-Monteith ETo input values, the Priestley-Taylor equation

  16. Electric and magnetic fields measured during a sudden impulse

    NASA Technical Reports Server (NTRS)

    Schutz, S.; Adams, G. J.; Mozer, F. S.

    1974-01-01

    The electric field in the ionosphere and the magnetic field at the earth's surface in the mid-latitude region were both measured during a sudden impulse. Ionospheric conductivities deduced from this data were consistent with expectations, thus suggesting that the fluctuations in the magnetic field at the earth's surface were caused by overhead ionospheric currents that were driven by an electric field associated with the sudden impulse.

  17. Field-aligned Electron Density Measurements and Comparison with Diffusive Equilibrium Models

    NASA Astrophysics Data System (ADS)

    Ozhogin, P.; Song, P.; Tu, J.; Reinisch, B. W.

    2012-12-01

    The diffusive equilibrium model describes the electron and ion densities along the magnetic field line in the plasmasphere and has been widely used in, for example, ray tracing and pitch-angle scattering calculations. It is based on the hydrostatic equilibrium with the electrostatic force that acts on ions and electrons along geomagnetic field lines while there is actually no motion or diffusion of the plasma involved. The model requires multiple input parameters: electron density and ion composition (H+, He+, O+) at a base level for a magnetic field line in the ionosphere, and the (electron or ion) temperature in the plasmasphere. It has been recognized that these input parameters have to be flexible from one field line to another so that the model output does not contradict some known observed relationship. However, while the flexibility provides the possibility to fit any individual observed density distribution which is measured across many different field lines, the model prediction becomes questionable along a single field line. Since the plasma density measurements along a single field line were not available until recently, the validity of the diffusive equilibrium models has not been verified independently. This study is to investigate both qualitatively and quantitatively whether the fundamental functional form of the diffusive equilibrium model can be useful and consistent with a large database of field-aligned electron density distributions from the radio plasma imager (RPI) instrument onboard the IMAGE satellite.

  18. New Limits on Extragalactic Magnetic Fields from Rotation Measures.

    PubMed

    Pshirkov, M S; Tinyakov, P G; Urban, F R

    2016-05-13

    We take advantage of the wealth of rotation measures data contained in the NRAO VLA Sky Survey catalog to derive new, statistically robust, upper limits on the strength of extragalactic magnetic fields. We simulate the extragalactic magnetic field contribution to the rotation measures for a given field strength and correlation length, by assuming that the electron density follows the distribution of Lyman-α clouds. Based on the observation that rotation measures from distant radio sources do not exhibit any trend with redshift, while the extragalactic contribution instead grows with distance, we constrain fields with Jeans' length coherence length to be below 1.7 nG at the 2σ level, and fields coherent across the entire observable Universe below 0.65 nG. These limits do not depend on the particular origin of these cosmological fields. PMID:27232014

  19. New Limits on Extragalactic Magnetic Fields from Rotation Measures

    NASA Astrophysics Data System (ADS)

    Pshirkov, M. S.; Tinyakov, P. G.; Urban, F. R.

    2016-05-01

    We take advantage of the wealth of rotation measures data contained in the NRAO VLA Sky Survey catalog to derive new, statistically robust, upper limits on the strength of extragalactic magnetic fields. We simulate the extragalactic magnetic field contribution to the rotation measures for a given field strength and correlation length, by assuming that the electron density follows the distribution of Lyman-α clouds. Based on the observation that rotation measures from distant radio sources do not exhibit any trend with redshift, while the extragalactic contribution instead grows with distance, we constrain fields with Jeans' length coherence length to be below 1.7 nG at the 2 σ level, and fields coherent across the entire observable Universe below 0.65 nG. These limits do not depend on the particular origin of these cosmological fields.

  20. Field measuring probe for SSC (Superconducting Super Collider) magnets

    SciTech Connect

    Ganetis, G.; Herrera, J.; Hogue, R.; Skaritka, J.; Wanderer, P.; Willen, E.

    1987-03-01

    The field probe developed for measuring the field in SSC dipole magnets is an adaptation of the rotating tangential coil system in use at Brookhaven for several years. Also known as the MOLE, it is a self-contained room-temperature mechanism that is pulled through the aperture of the magnet with regular stops to measure the local field. Several minutes are required to measure the field at each point. The probe measures the multipole components of the field as well as the field angle relative to gravity. The sensitivity of the coil and electronics is such that the field up to the full 6.6 T excitation of the magnet as well as the field when warm with only 0.01 T excitation can be measured. Tethers are attached to both ends of the probe to carry electrical connections and to supply dry nitrogen to the air motors that rotate the tangential windings as well as the gravity sensor. A small computer is attached to the probe for control and for data collection, analysis and storage. Digital voltmeters are used to digitize the voltages from the rotating coil and several custom circuits control motor speeds in the probe. The overall diameter of the probe is approximately 2 cm and its length is 2.4 m; the field sensitive windings are 0.6 m in length.

  1. Satellite measurements of high latitude convection electric fields.

    NASA Technical Reports Server (NTRS)

    Cauffman, D. P.; Gurnett, D. A.

    1972-01-01

    This paper reviews the first results of satellite experiments to measure magnetospheric convection electric fields using the double-probe technique. The earliest successful measurements were made with the low-altitude (680-2530 km) polar orbiting Injun-5 spacecraft. The Injun-5 results are compared with the initial findings of the electric field experiment on the polar orbiting OGO-6 satellite. Electric field measurements from the OGO-6 satellite have substantiated many of the initial Injun-5 observations with improved accuracy and sensitivity. The OGO-6 detector revealed the persistent occurrence of anti-sunward convection across the polar cap region at velocities not generally detectable with the Injun-5 experiment. The OGO-6 observations also provided information indicating that the location of the electric field reversal shifts equatorward during periods of increased magnetic activity. The implications of the electric field measurements for magnetospheric and auroral structure are summarized, and a list of specific recommendations for improving future experiments is presented.

  2. Field Variation of Low-field Anisotropy of Magnetic Susceptibility of Rocks: Measurement Problems

    NASA Astrophysics Data System (ADS)

    Hrouda, F.

    Theory of low-field anisotropy of magnetic susceptibility (AMS) assumes linear rela- tionship between magnetization and magnetizing field. This assumption is precisely valid in diamagnetic and paramagnetic minerals by definition, while in ferrimagnetic and antiferromagnetic minerals this relationship is in general non-linear, represented by hysteresis loop, being linear only in very weak fields in which the initial suscep- tibility is measured. Recently, it has been shown that, in using common measuring fields, the initial susceptibility is always measured in magnetite, while in pyrrhotite, hematite, and titanomagnetite the measured susceptibility may often be outside the initial susceptibility range. The field variation of low-field AMS results in lowering the quality of the fit of the susceptibility ellipsoid to the measured data and in mis- estimating the degree of anisotropy. Fortunately, the orientations of the principal sus- ceptibilities are virtually field-independent. The problem can be solved in basically three ways. The simplest way is using very weak measuring fields (less than 10 A/m), but this can result in significant lowering sensitivity and precision. The other way is to respect the non-linearity and measure the susceptibility in so many directions that contour diagram of directional susceptibilities can be presented instead of suscepti- bility ellipsoid. The third way is to measure the AMS in at least two fields within the Rayleigh law range and calculate the initial directional susceptibilities from which the AMS can be correctly determined using linear theory.

  3. The Self Actualized Reader.

    ERIC Educational Resources Information Center

    Marino, Michael; Moylan, Mary Elizabeth

    A study examined the commonalities that "voracious" readers share, and how their experiences can guide parents, teachers, and librarians in assisting children to become self-actualized readers. Subjects, 25 adults ranging in age from 20 to 67 years, completed a questionnaire concerning their reading histories and habits. Respondents varied in…

  4. Heteronuclear J-coupling measurements in grossly inhomogeneous magnetic fields.

    PubMed

    Mandal, S; Song, Y-Q

    2015-06-01

    It is difficult to measure chemical shifts in the small and inhomogeneous magnetic fields found in ex situ and single-sided NMR systems, such as those used for well-logging. However, it is still possible to obtain chemical information from J-coupling constants, which are independent of static field strength and temperature. We describe and analyze (1)H-(13)C double-resonance pulse sequences that are suitable for measuring heteronuclear J-coupling in grossly inhomogeneous fields. We also present preliminary experimental results from a low-frequency fringe-field system. PMID:25898398

  5. NASA-JSC antenna near-field measurement system

    NASA Technical Reports Server (NTRS)

    Cooke, W. P.; Friederich, P. G.; Jenkins, B. M.; Jameson, C. R.; Estrada, J. P.

    1988-01-01

    Work was completed on the near-field range control software. The capabilities of the data processing software were expanded with the addition of probe compensation. In addition, the user can process the measured data from the same computer terminal used for range control. The design of the laser metrology system was completed. It provides precise measruement of probe location during near-field measurements as well as position data for control of the translation beam and probe cart. A near-field range measurement system was designed, fabricated, and tested.

  6. Measurement of the gravity-field curvature by atom interferometry.

    PubMed

    Rosi, G; Cacciapuoti, L; Sorrentino, F; Menchetti, M; Prevedelli, M; Tino, G M

    2015-01-01

    We present the first direct measurement of the gravity-field curvature based on three conjugated atom interferometers. Three atomic clouds launched in the vertical direction are simultaneously interrogated by the same atom interferometry sequence and used to probe the gravity field at three equally spaced positions. The vertical component of the gravity-field curvature generated by nearby source masses is measured from the difference between adjacent gravity gradient values. Curvature measurements are of interest in geodesy studies and for the validation of gravitational models of the surrounding environment. The possibility of using such a scheme for a new determination of the Newtonian constant of gravity is also discussed. PMID:25615464

  7. Magnetic field models of nine CP stars from "accurate" measurements

    NASA Astrophysics Data System (ADS)

    Glagolevskij, Yu. V.

    2013-01-01

    The dipole models of magnetic fields in nine CP stars are constructed based on the measurements of metal lines taken from the literature, and performed by the LSD method with an accuracy of 10-80 G. The model parameters are compared with the parameters obtained for the same stars from the hydrogen line measurements. For six out of nine stars the same type of structure was obtained. Some parameters, such as the field strength at the poles B p and the average surface magnetic field B s differ considerably in some stars due to differences in the amplitudes of phase dependences B e (Φ) and B s (Φ), obtained by different authors. It is noted that a significant increase in the measurement accuracy has little effect on the modelling of the large-scale structures of the field. By contrast, it is more important to construct the shape of the phase dependence based on a fairly large number of field measurements, evenly distributed by the rotation period phases. It is concluded that the Zeeman component measurement methods have a strong effect on the shape of the phase dependence, and that the measurements of the magnetic field based on the lines of hydrogen are more preferable for modelling the large-scale structures of the field.

  8. Measurements and computations of electromagnetic fields in electric power substations

    SciTech Connect

    Daily, W.K. ); Dawalibi, F. )

    1994-01-01

    The magnetic fields generated by a typical distribution substation were measured and calculated based on a computer model which takes into account currents in the grounding systems, distribution feeder neutrals, overhead ground wires and induced currents in equipment structures and ground grid loops. Both measured and computer results indicate that magnetic fields are significantly influenced by ground currents, as well as induced currents in structures and ground system loops. All currents in the network modeled were computed, based on the measured currents impressed at the boundary points (ends of the conductor network). The agreement between the measured and computer values is good. Small differences were observed and are attributed mainly to uncertainties in the geometry of the network model and phase angles of some of the currents in the neutral conductors which were not measured in the field. Further measurements, including more accurate geometrical information and phase angles, are planned.

  9. Field measurements in the Fermilab electron cooling solenoid prototype

    SciTech Connect

    A. C. Crawford et al.

    2003-10-02

    To increase the Tevatron luminosity, Fermilab is developing a high-energy electron cooling system [1] to cool 8.9-GeV/c antiprotons in the Recycler ring. The schematic layout of the Recycler Electron Cooling (REC) system is shown in Figure 1. Cooling of antiprotons requires a round electron beam with a small angular spread propagating through a cooling section with a kinetic energy of 4.3 MeV. To confine the electron beam tightly and to keep its transverse angles below 10{sup -4} rad, the cooling section will be immersed into a solenoidal field of 50-150G. As part of the R&D effort, a cooling section prototype consisting of 9 modules (90% of the total length of a future section) was assembled and measured. This paper describes the technique of measuring and adjusting the magnetic field quality in the cooling section and presents preliminary results of solenoid prototype field measurements. The design of the cooling section solenoid is discussed in Chapter 2. Chapter 3 describes details of a dedicated measurement system, capable of measuring small transverse field components, while the system's measurement errors are analyzed in Chapter 4. Chapter 5 contains measured field distributions of individual elements of the cooling section as well as an evaluation of the magnetic shielding efficiency. An algorithm of field adjustments for providing lowest possible electron trajectory perturbations is proposed in Chapter 6; also, this chapter shows the results of our first attempts of implementing the algorithm.

  10. Magnetic Field Measurement and Compensation in the Recycler Electron Cooler

    SciTech Connect

    Tupikov, V.; Kroc, T. K.; Nagaitsev, S.; Prost, L.; Shemyakin, A.; Schmidt, C. W.; Sutherland, M.; Warner, A.; Kazakevich, G.

    2006-03-20

    Cooling of 8.9-GeV/c antiprotons in the Recycler Electron Cooler requires a round 4.34-MeV electron beam with a small angular spread propagating through a 20-m long cooling section. To confine the electron beam tightly and to keep its total transverse angles below 0.2 mrad the cooling section is immersed in a solenoidal field of 50-200 G. The field was measured with a compass-based sensor (transversal) and a hall-probe (longitudinal) after installation of the solenoids into the Recycler tunnel. For the field strength of 105 G, the transverse field components were compensated to the level that provided corresponding dipole beam oscillations below 0.1 mrad, which in turn allowed the first cooling of antiprotons in the GeV energy range. This paper discusses the field measurements and compensation scheme including the results of dipole oscillation measurements.

  11. Magnetic field measurement and compensation in the Recycler Electron Cooler

    SciTech Connect

    Tupikov, V.; Kazakevich, Grigory M.; Kroc, T.K.; Nagaitsev, S.; Prost, L.; Shemyakin, A.; Schmidt, C.W.; Sutherland, M.; Warner, A.; /Fermilab

    2005-09-01

    Cooling of 8.9-GeV/c antiprotons in the Recycler Electron Cooler requires a round 4.34-MeV electron beam with a small angular spread propagating through a 20-m long cooling section. To confine the electron beam tightly and to keep its total transverse angles below 0.2 mrad the cooling section is immersed in a solenoidal field of 50-200 G. The field was measured with a compass-based sensor (transversal) and a hall-probe (longitudinal) after installation of the solenoids into the Recycler tunnel. For the field strength of 105 G, the transverse field components were compensated to the level that provided corresponding dipole beam oscillations below 0.1 mrad, which in turn allowed the first cooling of antiprotons in the GeV energy range. This paper discusses the field measurements and compensation scheme including the results of dipole oscillation measurements.

  12. Theoretical and measured electric field distributions within an annular phased array: consideration of source antennas.

    PubMed

    Zhang, Y; Joines, W T; Jirtle, R L; Samulski, T V

    1993-08-01

    The magnitude of E-field patterns generated by an annular array prototype device has been calculated and measured. Two models were used to describe the radiating sources: a simple linear dipole and a stripline antenna model. The stripline model includes detailed geometry of the actual antennas used in the prototype and an estimate of the antenna current based on microstrip transmission line theory. This more detailed model yields better agreement with the measured field patterns, reducing the rms discrepancy by a factor of about 6 (from approximately 23 to 4%) in the central region of interest where the SEM is within 25% of the maximum. We conclude that accurate modeling of source current distributions is important for determining SEM distributions associated with such heating devices. PMID:8258444

  13. Magnetic-field measurements for the Lewis Research Center cyclotron

    NASA Technical Reports Server (NTRS)

    Fessler, T. E.

    1973-01-01

    The magnetic field of the Lewis Center cyclotron was mapped by using a Hall-effect magnetic-field transducer. Main-field Fourier coefficients were determined on a polar mesh of 40 radii for each of seven levels of main-field coil current. Incremental fields for eight sets of trim coils and two sets of harmonic coils were also determined at four of these main-field levels. A stored-program, digital computer was used to perform the measurements. The process was entirely automatic; all data-taking and data-reduction activities were specified by the computer programs. A new method for temperature compensation of a Hall element was used. This method required no temperature control of the element. Measurements of the Hall voltage and Hall-element resistance were sufficient to correct for temperature effects.

  14. Instructions for 104-SX liquid level measurement field tests

    SciTech Connect

    Webb, R.H.

    1994-10-01

    This document provides detailed instructions for field testing a suggested solution of inserting a liner inside the 104-SX failed Liquid Observation Well to gain access for making temporary Liquid Level Measurement until a permanent solution has been provided.

  15. Pulsar rotation and dispersion measures and the galactic magnetic field.

    NASA Technical Reports Server (NTRS)

    Manchester, R. N.

    1972-01-01

    Use of observations of pulsar polarization and pulse time of arrival at frequencies between 250 and 500 MHz to determine rotation and dispersion measures for 19 and 21 pulsars, respectively. These measurements have been used to calculate mean line-of-sight components of the magnetic field in the path to the pulsars. These and other observations show that there is probably no contribution to the observed rotation measure from the pulsar itself. Low-latitude, low-dispersion pulsars are observed to have strong field components, and a strong dependence of rotation-measure sign on galactic longitude has been found. The observations are consistent with a relatively uniform field of about 3.5 microgauss directed toward about l = 90 deg in the local region, but appear to be inconsistent with the helical model for the local field.

  16. Measurement of magnetic field using Rayleigh backscattering in optical fibres

    SciTech Connect

    Wuilpart, M.; Caucheteur, C.; Goussarov, A.; Aerssens, M.; Massaut, V.; Megret, P.

    2011-07-01

    In this paper, we investigate the use of optical reflectometry in optical fibres for the measurement of magnetic field. The dedicated application concerns the measurement of plasma current in the fusion reactor. The measurement is based on the rotation of the polarization state of the Rayleigh backscattered signal when an optical pulse is launched in the fibre. Particular care has been undertaken to evaluate the impact of linear birefringence on the measurement performance. (authors)

  17. Measuring Helical FCG Voltage with an Electric Field Antenna

    SciTech Connect

    White, A D; Anderson, R A; Javedani, J B; Reisman, D B; Goerz, D A; Ferriera, A J; Speer, R D

    2011-08-01

    A method of measuring the voltage produced by a helical explosive flux compression generator using a remote electric field antenna is described in detail. The diagnostic has been successfully implemented on several experiments. Measured data from the diagnostic compare favorably with voltages predicted using the code CAGEN, validating our predictive modeling tools. The measured data is important to understanding generator performance, and is measured with a low-risk, minimally intrusive approach.

  18. Instrumentation used to measure residential magnetic fields and currents.

    PubMed

    Lahijanian, H; Yatapanage, K; Rosen, R; Cross, J

    2003-10-01

    The equipment used to measure magnetic fields and electric currents in residences is described. The instrumentation consisted of current transformers, magnetic field probes and locally designed and built signal conditioning modules. The data acquisition system was capable of unattended recording for extended time periods. The complete system was calibrated to verify its response to known physical inputs. PMID:14582878

  19. A framework for modelling kinematic measurements in gravity field applications

    NASA Technical Reports Server (NTRS)

    Schwarz, K. P.; Wei, M.

    1989-01-01

    To assess the resolution of the local gravity field from kinematic measurements, a state model for motion in the gravity field of the earth is formulated. The resulting set of equations can accommodate gravity gradients, specific force, acceleration, velocity and position as input data and can take into account approximation errors as well as sensor errors.

  20. COMPARABILITY BETWEEN VARIOUS FIELD AND LABORATORY WOODSTOVE EMISSION MEASUREMENT METHODS

    EPA Science Inventory

    The paper compares various field and laboratory woodstove emission measurement methods. n 1988, the U.S. EPA promulgated performance standards for residential wood heaters (woodstoves). ver the past several years, a number of field studies have been undertaken to determine the ac...

  1. Experimental Validation of Simulations Using Full-field Measurement Techniques

    SciTech Connect

    Hack, Erwin

    2010-05-28

    The calibration by reference materials of dynamic full-field measurement systems is discussed together with their use to validate numerical simulations of structural mechanics. The discussion addresses three challenges that are faced in these processes, i.e. how to calibrate a measuring instrument that (i) provides full-field data, and (ii) is dynamic; (iii) how to compare data from simulation and experimentation.

  2. Swarm Measurements of Ionospheric Electric Field and Plasma

    NASA Astrophysics Data System (ADS)

    Burchill, J.; Knudsen, D.; Eriksson, A.

    2009-05-01

    Swarm is a three-spacecraft European Space Agency Earth Explorer mission that will include precision in-situ measurements of magnetic field, electric field, and plasma parameters at altitudes up to 530 km, twice per second for four years beginning in late 2010. Electric fields in the direction perpendicular to the local magnetic field will be measured by the Swarm Electric Field Instruments (EFI) using a technique based on measurements of ion drift. The Swarm EFI's represent a new generation of ion drift measurement in that they use an intensified CCD-based technique to generate 2-D images of low-energy ion distribution functions from which both ion drift velocity and temperature are derived. These measurements will be complemented by Langmuir-probe measurements of electron density, electron temperature and spacecraft potential. We present an overview of the mission and of the predicted performance characteristics of the EFI, and examine the benefits of the Swarm configuration for ionospheric research relative to previous precision magnetic field research missions such as Ørsted and CHAMP.

  3. Aircraft measurement of electric field - Self-calibration

    NASA Technical Reports Server (NTRS)

    Winn, W. P.

    1993-01-01

    Aircraft measurement of electric fields is difficult as the electrically conducting surface of the aircraft distorts the electric field. Calibration requires determining the relations between the undistorted electric field in the absence of the vehicle and the signals from electric field meters that sense the local distorted fields in their immediate vicinity. This paper describes a generalization of a calibration method which uses pitch and roll maneuvers. The technique determines both the calibration coefficients and the direction of the electric vector. The calibration of individual electric field meters and the elimination of the aircraft's self-charge are described. Linear combinations of field mill signals are examined and absolute calibration and error analysis are discussed. The calibration method was applied to data obtained during a flight near thunderstorms.

  4. Mesodynamics in the SARS nucleocapsid measured by NMR field cycling.

    PubMed

    Clarkson, Michael W; Lei, Ming; Eisenmesser, Elan Z; Labeikovsky, Wladimir; Redfield, Alfred; Kern, Dorothee

    2009-09-01

    Protein motions on all timescales faster than molecular tumbling are encoded in the spectral density. The dissection of complex protein dynamics is typically performed using relaxation rates determined at high and ultra-high field. Here we expand this range of the spectral density to low fields through field cycling using the nucleocapsid protein of the SARS coronavirus as a model system. The field-cycling approach enables site-specific measurements of R (1) at low fields with the sensitivity and resolution of a high-field magnet. These data, together with high-field relaxation and heteronuclear NOE, provide evidence for correlated rigid-body motions of the entire beta-hairpin, and corresponding motions of adjacent loops with a time constant of 0.8 ns (mesodynamics). MD simulations substantiate these findings and provide direct verification of the time scale and collective nature of these motions. PMID:19641854

  5. Performance of field measuring probes for SSC magnets

    SciTech Connect

    Thomas, R.; Ganetis, G.; Herrera, J.; Hogue, R.; Jain, A.; Louie, W.; Marone, A.; Wanderer, P.

    1993-12-31

    Several years of experience have been acquired on the operation of probes (``moles``) constructed for the measurement of the multipole components of the magnetic fields of SSC magnets. The field is measured by rotating coils contained in a 2.4-m long tube that is pulled through the aperture of the magnet by an external device-the transporter. In addition to the measuring coils, the tube contains motors for rotating the coil and a system for sensing local vertical using gravity sensors to provide an absolute reference for the field measurements. We describe the steps that must be taken in order to ensure accurate, repeatable measurements; the design changes that have been motivated by difficulties encountered (noise, vibration, variations in temperature); and other performance issues. The mechanical interface between the probe and the hewn tube of the magnet is also described.

  6. Measurement of radiofrequency electromagnetic fields in and around ambulances.

    PubMed

    Boivin, W S; Boyd, S M; Coletta, J A; Neunaber, L M

    1997-01-01

    Electromagnetic interference (EMI) with medical devices can threaten patient safety. More information is needed regarding circumstances in health care environments in which electromagnetic (EM) field strengths are expected to be high, such as emergency/transport. In ambulances medical devices and communications equipment must function properly in close proximity. This study characterized EM fields in and around ambulances under realistic conditions. Two types of ambulances were surveyed: the advanced life support (ALS) unit and the basic life support (BLS) unit. The surveys were conducted on-site using the ambulance mobile radio as the primary source of EM energy. Broadband field-strength measurements were collected at various locations in and around the ambulance to map interior and exterior EM field distributions. Nine ambulances were surveyed. In addition to the transmitter power and frequency, the field strengths measured were shown to be dependent upon the shielding provided by the ambulance roof and proximity of the measurement probe to the antenna. Field-strength measurements frequently exceeded the 3 V/m standard immunity level for devices set by the IEC Standard 601-1-2. The results indicate that the ambulance environment presents a considerable challenge to medical devices specifically used for emergency medical care. In order to assure their proper operation, medical devices used for transport emergency care must be able to withstand exposure to EM field strengths comparable to those reported in this study. PMID:9099436

  7. High electric field measurement using slab-coupled optical sensors.

    PubMed

    Stan, Nikola; Seng, Frederick; Shumway, LeGrand; King, Rex; Selfridge, Richard; Schultz, Stephen

    2016-01-20

    A fiber-optic electric field sensor was developed to measure electric field up to 18 MV/m. The sensor uses resonant coupling between an optical fiber and a nonlinear electro-optical crystal. The sensing system uses high dielectric strength materials to eliminate dielectric breakdown. A postprocessing nonlinear calibration method is developed that maps voltage change to wavelength shift and then converts the wavelength shift to electric field using the transmission spectrum. The nonlinear calibration method is compared against the linear method with electric field pulses having magnitudes from 1.5 to 18 MV/m. PMID:26835936

  8. Ambient temperature field measuring system for LHC superconducting dipoles

    SciTech Connect

    Billan, J.; De Panfilis, S.; Giloteaux, D.; Pagano, O.

    1996-07-01

    It is foreseen to perform acceptance tests including field measurements of the collared coils assembly of the LHC superconducting dipoles to estimate, at an early production stage, the possible significant deviations from the expected multipole component value of these magnets. A sensitive measuring probe and efficient data acquisition are the consequence of a low magnetizing current necessary to limit the coils heating. This demands a high signals sensitivity and an enhanced signal-to-noise ratio to retrieve the higher multipole component. Moreover, the correlation with the multipoles content of the magnets at cryogenic temperature and nominal excitation current need to be identified before the manufacturing process may continue. The field probe of the mole-type is equipped with three radial rotating search coils, an angular encoder and gravity sensor. It has been designed to slide inside the bore of the dipole coils and to measure the local field at fixed positions. The field analysis resulting in terms of multipole components, field direction and field integrals, measured on four 10 m long, twin-aperture LHC dipole prototypes, will be described together with the performance of the measuring method.

  9. Rocket borne instrument to measure electric fields inside electrified clouds

    NASA Technical Reports Server (NTRS)

    Ruhnke, L. H. (Inventor)

    1973-01-01

    An apparatus for measuring the electric field in the atmosphere which includes a pair of sensors carried on a rocket for sensing the voltages in the atmosphere being measured is described. One of the sensors is an elongated probe with a fine point which causes a corona current to be produced as it passes through the electric field. An electric circuit is coupled between the probe and the other sensor and includes a high ohm resistor which linearizes the relationship between the corona current and the electric field being measured. A relaxation oscillator and transmitter are provided for generating and transmitting an electric signal having a frequency corresponding to the magnitude of the electric field.

  10. The plasmaspheric electric field as measured by ISEE 1

    NASA Technical Reports Server (NTRS)

    Maynard, N. C.; Aggson, T. L.; Heppner, J. P.

    1983-01-01

    The electrodynamics of the plasmasphere has been a topic of considerable interest. Models predict a space charge buildup, or Alfven layer, at the inner edge of the ring current which opposes the dawn-dusk convection electric field in the magnetosphere and thus shields the plasmasphere from the convection electric field. The current study has the objective to present data from the ISEE 1 double cylindrical probe instrument. All measurements reported were made in the plasmasphere with electron densities of the order of 30-50 or greater per cu cm. The average electric field pattern for quiet conditions is found to be qualitatively consistent with previous average results from whistler measurements and radar backscattering measurements. The magnitudes and gross patterns are in qualitative agreement with representative ionospheric dynamo models. The basic convective flow vectors from the penetration of the magnetospheric electric field tend to follow contours which are parallel to those of the average plasmapause boundary on the nightside.

  11. Velocity field measurement of a round jet using quantitative schlieren.

    PubMed

    Iffa, Emishaw D; Aziz, A Rashid A; Malik, Aamir S

    2011-02-10

    This paper utilizes the background oriented schlieren (BOS) technique to measure the velocity field of a variable density round jet. The density field of the jet is computed based on the light deflection created during the passage of light through the understudy jet. The deflection vector estimation was carried out using phase-based optical flow algorithms. The density field is further exploited to extract the axial and radial velocity vectors with the aid of continuity and energy equations. The experiment is conducted at six different jet-exit temperature values. Additional turbulence parameters, such as velocity variance and power spectral density of the vector field, are also computed. Finally, the measured velocity parameters are compared with the hot wire anemometer measurements and their correlation is displayed. PMID:21343981

  12. Electric Field Measurements of the Capacitively Coupled Magnetized RF Sheath Utilizing Passive Optical Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Martin, Elijah Henry

    A major challenge facing magnetic confinement fusion is the implementation of reliable plasma heating systems. Ion cyclotron resonance heating (ICRH) is a key technique utilized to achieve the ion temperatures necessary for desirable fusion reaction rates. ICRH systems are designed to couple energy into the core plasma ions through a resonant interaction with an electromagnetic wave in the radio frequency range. The interaction of the wave with the scrape off layer plasma establishes an electric field which terminates directly on the plasma facing surfaces and is referred to as the near-field. In order to bridge the gap between the theoretical and actual performance of ICRF antennas, experimental measurement of this electric field is highly desired. However, due to the large amount of power launched by ICRF antennas only non-local measurements have thus far been obtained. The research presented in this dissertation is centered on the development of a non-perturbative diagnostic to locally measure the near-field with high spatial and temporal resolution. The main objective of the research presented in this dissertation is to develop and validate a spectroscopic diagnostic capable of measuring local time periodic electric fields. The development phase of the diagnostic consisted of atomic physics formulation and was carried out in two steps. The first involved the calculation of the electronic structure of the one and two-electron atom utilizing the hydrogenic wave function. The second involved the calculation of the spectral line profile based on the electric dipole connection operator. The validate phase of the diagnostic consisted of implementation of the atomic physics to measure the electric field topology associated with the capacitively coupled magnetized RF sheath using passive OES. The experimental measurements are then compared to a simple one-dimensional analytical model providing the validation of the developed atomic physics.

  13. Real-World Physics: A Portable MBL for Field Measurements.

    ERIC Educational Resources Information Center

    Albergotti, Clifton

    1994-01-01

    Uses a moderately priced digital multimeter that has output and software compatible with personal computers to make a portable, computer-based data-acquisition system. The system can measure voltage, current, frequency, capacitance, transistor hFE, and temperature. Describes field measures of velocity, acceleration, and temperature as function of…

  14. Position measuring system for applications in field sports

    NASA Astrophysics Data System (ADS)

    Hristoforou, E.; Chiriac, H.

    2002-08-01

    In this paper, an automated system able to measure performance in field sports is presented. The system can detect automatically the length of jumps and triple jumps as well as the position of throws in field sports. The method of detection is based on an application-specific magnetostrictive delay line set-up, using the delay time due to the acoustic signal propagation. The system is able to perform measurements with an accuracy better than 1 mm, thus overcoming the present semi-automatic or manual techniques of measurement.

  15. Magsat: A satellite for measuring near earth magnetic fields

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Regan, R. D.; Murphy, J. P.

    1977-01-01

    Magsat, designed for making measurements of the geomagnetic vector field, is evaluated. For accurate vector measurements the attitude of the fluxgate magnetometer will be determined to about 15 arc-seconds. Expected measurement accuracy will be 6 (gamma) in each component and 3 in magnitude. The Magsat data will be applied to solid earth studies including modeling of the Earth's main magnetic field, delineation of regional magnetic anomalies of crustal origin, and interpretation of those anomalies in terms of geologic and geophysical models. An opportunity will be presented to the scientific community to participate in data use investigations.

  16. Measurement and control of field in RF GUN at FLASH

    NASA Astrophysics Data System (ADS)

    Brandt, A.; Hoffmann, M.; Koprek, W.; Pucyk, P.; Simrock, S.; Pozniak, K. T.; Romaniuk, R. S.

    2008-01-01

    The paper describes the hardware and software architecture of a control and measurement system for electromagnetic field stabilization inside the radio frequency electron gun, in FLASH experiment. A complete measurement path has been presented, including I and Q detectors and FPGA based, low latency digital controller. Algorithms used to stabilize the electromagnetic field have been presented as well as the software environment used to provide remote access to the control device. An input signal calibration procedure has been described as a crucial element of measurement process.

  17. Four Point Magnetic Field Measurements of Magnetosheath Fluctuations

    NASA Astrophysics Data System (ADS)

    Horbury, T. S.; Lucek, E. A.; Balogh, A.; Dunlop, M. W.; Dandouras, I.

    Using magnetic field measurements made at the four Cluster spacecraft separated by several hundred km, it is possible to measure the three dimensional correlation tensor of waves, turbulence and structures in the magnetosheath. In this way, their correlation scales, anisotropy and three dimensional power spectra can be estimated. As an exam- ple, we present such measurements of mirror mode structures and estimate their corre- lation lengths along and across the magnetic field direction. We also present an analy- sis of broadband magnetosheath MHD turbulence, and in particular its anisotropy, and compare the results to the properties of solar wind MHD turblence.

  18. Field quality measurements of a 2-Tesla transmission line magnet

    SciTech Connect

    Velev, G.V.; Foster, W.; Kashikhin, V.; Mazur, P.; Oleck, A.; Piekarz, H.; Schlabach, P.; Sylvester, C.; Wake, M.; /KEK, Tsukuba

    2005-09-01

    A prototype 2-Tesla superconducting transmission line magnet for future hadron colliders was designed, built and tested at Fermilab. The 1.5 m long, combined-function gradient-dipole magnet has a vertical pole aperture of 20 mm. To measure the magnetic field quality in such a small magnet aperture, a specialized rotating coil of 15.2 mm diameter, 0.69 m long was fabricated. Using this probe, a program of magnetic field quality measurements was successfully performed. Results of the measurements are presented and discussed.

  19. Interpolation And FFT Of Near-Field Antenna Measurements

    NASA Technical Reports Server (NTRS)

    Gatti, Mark S.; Rahmat-Samii, Yahya

    1990-01-01

    Bivariate Lagrange interpolation applied to plane-polar measurement scans. Report discusses recent advances in application of fast-Fourier-transform (FFT) techniques to measurements of near radiation fields of antennas on plane-polar grid. Attention focused mainly on use of such measurements to calculate far radiation fields. Also discussion of use of FFT's in holographic diagnosis of distortions of antenna reflectors. Advantage of scheme, it speeds calculations because it requires fewer data and manipulations of data than other schemes used for this purpose.

  20. Factors Related to Self-Actualization.

    ERIC Educational Resources Information Center

    Hogan, H. Wayne; McWilliams, Jettie M.

    1978-01-01

    Provides data to further support the notions that females score higher in self-actualization measures and that self-actualization scores correlate inversely to the degree of undesirability individuals assign to their heights and weights. Finds that, contrary to predictions, greater androgyny was related to lower, not higher, self-actualization…

  1. Ultrasensitive 3He magnetometer for measurements of high magnetic fields

    NASA Astrophysics Data System (ADS)

    Nikiel, Anna; Blümler, Peter; Heil, Werner; Hehn, Manfred; Karpuk, Sergej; Maul, Andreas; Otten, Ernst; Schreiber, Laura M.; Terekhov, Maxim

    2014-11-01

    We describe a 3He magnetometer capable to measure high magnetic fields ( B> 0.1 T) with a relative accuracy of better than 10-12. Our approach is based on the measurement of the free induction decay of gaseous, nuclear spin polarized 3He following a resonant radio frequency pulse excitation. The measurement sensitivity can be attributed to the long coherent spin precession time T2 ∗ being of order minutes which is achieved for spherical sample cells in the regime of "motional narrowing" where the disturbing influence of field inhomogeneities is strongly suppressed. The 3He gas is spin polarized in situ using a new, non-standard variant of the metastability exchange optical pumping. We show that miniaturization helps to increase T2 ∗ further and that the measurement sensitivity is not significantly affected by temporal field fluctuations of order 10-4.

  2. Auditory evoked field measurement using magneto-impedance sensors

    NASA Astrophysics Data System (ADS)

    Wang, K.; Tajima, S.; Song, D.; Hamada, N.; Cai, C.; Uchiyama, T.

    2015-05-01

    The magnetic field of the human brain is extremely weak, and it is mostly measured and monitored in the magnetoencephalography method using superconducting quantum interference devices. In this study, in order to measure the weak magnetic field of the brain, we constructed a Magneto-Impedance sensor (MI sensor) system that can cancel out the background noise without any magnetic shield. Based on our previous studies of brain wave measurements, we used two MI sensors in this system for monitoring both cerebral hemispheres. In this study, we recorded and compared the auditory evoked field signals of the subject, including the N100 (or N1) and the P300 (or P3) brain waves. The results suggest that the MI sensor can be applied to brain activity measurement.

  3. Auditory evoked field measurement using magneto-impedance sensors

    SciTech Connect

    Wang, K. Tajima, S.; Song, D.; Uchiyama, T.; Hamada, N.; Cai, C.

    2015-05-07

    The magnetic field of the human brain is extremely weak, and it is mostly measured and monitored in the magnetoencephalography method using superconducting quantum interference devices. In this study, in order to measure the weak magnetic field of the brain, we constructed a Magneto-Impedance sensor (MI sensor) system that can cancel out the background noise without any magnetic shield. Based on our previous studies of brain wave measurements, we used two MI sensors in this system for monitoring both cerebral hemispheres. In this study, we recorded and compared the auditory evoked field signals of the subject, including the N100 (or N1) and the P300 (or P3) brain waves. The results suggest that the MI sensor can be applied to brain activity measurement.

  4. Magnetic Field Measurements in Plasmas: Beyond the Traditional Zeeman Spectroscopy

    SciTech Connect

    Doron, R.; Stambulchik, E.; Tessarin, S.; Kroupp, E.; Citrin, J.; Maron, Y.; Tsigutkin, K.

    2009-09-10

    We discuss a new approach to measure magnetic fields in situations where the magnetic-field properties and/or the plasma regime make the traditional Zeeman spectroscopy inapplicable. The approach is particularly useful when the field direction and/or magnitude vary significantly in the region viewed or during the diagnostic system's integration time, and hence no Zeeman splitting can be observed. Similar difficulty may also occur for high-energy-density conditions, where the Zeeman pattern is often completely smeared, regardless of the field distribution, due to the dominant contributions of the Stark and Doppler broadenings to the spectral-line shapes. In the new approach, the magnetic field is inferred from the comparison of the line-shapes of different fine-structure components of the same multiplet, which practically have the same Stark and Doppler broadenings, but different magnetic-field-induced contributions. Limitations of the new method are discussed.

  5. High-frequency electric field measurement using a toroidal antenna

    DOEpatents

    Lee, Ki Ha

    2002-01-01

    A simple and compact method and apparatus for detecting high frequency electric fields, particularly in the frequency range of 1 MHz to 100 MHz, uses a compact toroidal antenna. For typical geophysical applications the sensor will be used to detect electric fields for a wide range of spectrum starting from about 1 MHz, in particular in the frequency range between 1 to 100 MHz, to detect small objects in the upper few meters of the ground. Time-varying magnetic fields associated with time-varying electric fields induce an emf (voltage) in a toroidal coil. The electric field at the center of (and perpendicular to the plane of) the toroid is shown to be linearly related to this induced voltage. By measuring the voltage across a toroidal coil one can easily and accurately determine the electric field.

  6. Direct analysis of dispersive wave fields from near-field pressure measurements.

    PubMed

    Hörchens, Lars

    2011-10-01

    Flexural waves play a significant role for the radiation of sound from plates. The analysis of flexural wave fields enables the detection of sources and transmission paths in plate-like structures. The measurement of these wave fields can be carried out indirectly by means of near-field acoustic holography, which determines the vibrational wave field from pressure information measured in a plane close to the plate under investigation. The reconstruction of the plate vibration is usually obtained by inverting the forward radiation problem, i.e., by inversion of an integral operator. In this article, it is shown that a pressure measurement taken in the extreme near-field of a vibrating plate can directly be used for the approximate analysis of the dispersive flexural wave field. The inversion step of near-field acoustic holography is not necessarily required if such an approximate solution is sufficient. The proposed method enables fast and simple analysis of dispersion characteristics. Application of dispersion compensation to the measured field allows for visualizations of propagating wavefronts, such that sources and scatterers in the plate can be detected. The capabilities of the described approach are demonstrated on several measurements. PMID:21973358

  7. Linewidth-modulated motional Stark effect measurements of internal field structure in low-field configurations

    NASA Astrophysics Data System (ADS)

    Reinecke, E. A.; Fonck, R. J.; Thorson, T. A.

    2001-01-01

    Motional Stark effect measurements of internal field structure in low-field magnetic confinement configurations are considered for both magnitude and direction of the local magnetic field. The amplitude and phase delay of an oscillating spectral linewidth driven by a rotating polarizer provides a means of determining the magnitude and direction of the total field simultaneously while avoiding difficulties of neutral beam energy drift. Photon-noise limit estimates for a diagnostic beam on the low-field PEGASUS toroidal experiment indicate sensitivities of roughly 20 G and 0.2° for the magnitude and direction angle. These values are sufficient to provide significant constraints on magnetic equilibrium reconstructions.

  8. Linewidth-modulated motional Stark effect measurements of internal field structure in low-field configurations

    SciTech Connect

    Reinecke, E. A.; Fonck, R. J.; Thorson, T. A.

    2001-01-01

    Motional Stark effect measurements of internal field structure in low-field magnetic confinement configurations are considered for both magnitude and direction of the local magnetic field. The amplitude and phase delay of an oscillating spectral linewidth driven by a rotating polarizer provides a means of determining the magnitude and direction of the total field simultaneously while avoiding difficulties of neutral beam energy drift. Photon-noise limit estimates for a diagnostic beam on the low-field PEGASUS toroidal experiment indicate sensitivities of roughly 20 G and 0.2{sup o} for the magnitude and direction angle. These values are sufficient to provide significant constraints on magnetic equilibrium reconstructions.

  9. Integrating sphere transmissometer for field measurement of leaf transmittance

    NASA Astrophysics Data System (ADS)

    Vanderbilt, V. C.; Dewitt, D. P.; Robinson, B. F.

    1987-12-01

    A simple field-rated transmissometer is described for rapidly determining the normal hemispherical transmittance T(0 deg, 2 pi) of leaves measured in situ in the four Landsat wavelength bands. The transmissometer requires direct solar illumination of the leaf sample. It collects the transmitted light with an integrating sphere and measures the collected light using a commercially available radiometer. The transmittances determined by the transmissometer are comparable with those measured by a labortory spectrophotometer with an integrating sphere attachment.

  10. Actual evapotranspiration estimation in a Mediterranean mountain region by means of Landsat-5 TM and TERRA/AQUA MODIS imagery and Sap Flow measurements in Pinus sylvestris forest stands.

    NASA Astrophysics Data System (ADS)

    Cristóbal, J.; Poyatos, R.; Ninyerola, M.; Pons, X.; Llorens, P.

    2009-04-01

    Elevation Model, obtaining an RMS less than 30 m. Radiometric correction of Landsat non-thermal bands has been done following the methodology proposed by Pons and Solé (1994) which allows to reduce the number of undesired artifacts that are due to the effects of the atmosphere or to the differential illumination which is, in turn, due to the time of the day, the location in the Earth and the relief (zones being more illuminated than others, shadows, etc). Atmospheric correction of Landsat thermal band has been carried out by means of a single-channel algorithm improvement developed by Cristóbal et al. (2009). To compute actual evapotranspiration (AET) we have used the B-Method proposed by Jakson et al. (1977) and modified by Carlson et al. (1995) and Caselles et al. (1998), based on the energy budget, that needs as an input variables net radiation (Rn) and the difference between land surface temperature (LST) and air temperature (Ta). Air temperature has been modelled by means of multiple regression analysis and GIS interpolation using ground meteorological stations. Net radiation have been computed following two approaches based on the energy balance equation using albedo, land surface temperature, air temperature and solar radiation. Both air temperature and net radiation have been modelled at a regional scale. We have compared remote sensing daily actual evapotranspiration estimates with measured canopy transpiration. Sap flux density was measured by means of Heat dissipation sensors in 12 trees per stand, sampled according to diametric distribution, corrected to account for radial patter of sap flow using the Heat Field Deformation method and then scaled-up to stand level transpiration using tree sapwood areas. Sap flow measurements are comparable with AETd as in the Scots pine stand understorey evaporation is not significant. Measurements with sap flow technique show a mean, minimum and maximum values of AETd = 2.2, 0.6 and 3.6 mm day -1, respectively (Poyatos et al

  11. Magnetic-Field-Response Measurement-Acquisition System

    NASA Technical Reports Server (NTRS)

    Woodward, Stanley E.; Shams, Qamar A.; Fox, Robert L.; Taylor, Bryant D.

    2006-01-01

    A measurement-acquisition system uses magnetic fields to power sensors and to acquire measurements from sensors. The system alleviates many shortcomings of traditional measurement-acquisition systems, which include a finite number of measurement channels, weight penalty associated with wires, use limited to a single type of measurement, wire degradation due to wear or chemical decay, and the logistics needed to add new sensors. Eliminating wiring for acquiring measurements can alleviate potential hazards associated with wires, such as damaged wires becoming ignition sources due to arcing. The sensors are designed as electrically passive inductive-capacitive or passive inductive-capacitive-resistive circuits that produce magnetic-field-responses. One or more electrical parameters (inductance, capacitance, and resistance) of each sensor can be variable and corresponds to a measured physical state of interest. The magnetic-field- response attributes (frequency, amplitude, and bandwidth) of the inductor correspond to the states of physical properties for which each sensor measures. For each sensor, the measurement-acquisition system produces a series of increasing magnetic-field harmonics within a frequency range dedicated to that sensor. For each harmonic, an antenna electrically coupled to an oscillating current (the frequency of which is that of the harmonic) produces an oscillating magnetic field. Faraday induction via the harmonic magnetic fields produces an electromotive force and therefore a current in the sensor. Once electrically active, the sensor produces its own harmonic magnetic field as the inductor stores and releases magnetic energy. The antenna of the measurement- acquisition system is switched from a transmitting to a receiving mode to acquire the magnetic-field response of the sensor. The rectified amplitude of the received response is compared to previous responses to prior transmitted harmonics, to ascertain if the measurement system has detected a

  12. A 3-D measurement of biomagnetic field and its application

    NASA Astrophysics Data System (ADS)

    Uchikawa, Yoshinori; Kim, Bong-Soo; Kobayashi, Koichiro

    2006-09-01

    This review paper focuses in the usefulness of three-dimensional (3-D) biomagnetic field measurement for discriminating multiple sources closely located and overlapped in time. We have developed a 3-D second-order gradiometer connected to 39-channel SQUIDs for vector measurement of magnetoencephalogram (MEG), which can simultaneously detect magnetic field components perpendicular and tangential to the scalp. To assess discrimination and separation of multiple sources overlapping in time, we showed both simulation study and 3-D vector measurement of MEG as following; (a) mixed auditory evoked field (AEF) and somatosensory evoked field (SEF), (b) separating second somatosensory (SII) activity from primary somatosensory (SI) activity in SEF. The magnetic field distribution perpendicular to the scalp was not helpful for estimating the location and number of sources, owing to the lack of a dipole pattern, but the magnetic field distribution tangential to the scalp can provide information about new constraint conditions by visual inspection and singular value decomposition (SVD) method. We estimated multiple sources of mixed AEF and SEF from the MEG data of the magnetic field tangential to the scalp, and also estimated multiple sources of SI and SII activity. These results were confirmed by comparison with superimposed source locations in MRI of subject's head.

  13. Measuring Earth's Local Magnetic Field Using a Helmholtz Coil

    NASA Astrophysics Data System (ADS)

    Williams, Jonathan E.

    2014-04-01

    In this paper, I present a low-cost interactive experiment for measuring the strength of Earth's local magnetic field. This activity can be done in most high schools or two-year physics laboratories with limited resources, yet will have a tremendous learning impact. This experiment solidifies the three-dimensional nature of Earth's magnetic field vector and helps reinforce the aspect of the vertical component of Earth's magnetic field. Students should realize that Earth's magnetic field is not fully horizontal (except at the magnetic equator) and that a compass simply indicates the direction of the horizontal component of Earth's magnetic field. A magnetic dip needle compass can be used to determine the angle (known as the "dip angle" or "inclination angle") measured from the direction in which Earth's magnetic field vector points to the horizontal. In this activity, students will be able to determine the horizontal component of the field using a Helmholtz coil and, knowing the dip angle, the Earth's magnetic field strength can be determined.

  14. The Electron Drift Technique for Measuring Electric and Magnetic Fields

    NASA Technical Reports Server (NTRS)

    Paschmann, G.; McIlwain, C. E.; Quinn, J. M.; Torbert, R. B.; Whipple, E. C.; Christensen, John (Technical Monitor)

    1998-01-01

    The electron drift technique is based on sensing the drift of a weak beam of test electrons that is caused by electric fields and/or gradients in the magnetic field. These quantities can, by use of different electron energies, in principle be determined separately. Depending on the ratio of drift speed to magnetic field strength, the drift velocity can be determined either from the two emission directions that cause the electrons to gyrate back to detectors placed some distance from the emitting guns, or from measurements of the time of flight of the electrons. As a by-product of the time-of-flight measurements, the magnetic field strength is also determined. The paper describes strengths and weaknesses of the method as well as technical constraints.

  15. Radiological Disaster Simulators for Field and Aerial Measurements

    SciTech Connect

    H. W. Clark, Jr

    2002-11-01

    Simulators have been developed to dramatically improve the fidelity of play for field monitors and aircraft participating in radiological disaster drills and exercises. Simulated radiological measurements for the current Global Positioning System (GPS) location are derived from realistic models of radiological consequences for accidents and malicious acts. The aerial version outputs analog pulses corresponding to the signal that would be produced by various NaI (Tl) detectors at that location. The field monitor version reports the reading for any make/model of survey instrument selected. Position simulation modes are included in the aerial and field versions. The aerial version can generate a flight path based on input parameters or import an externally generated sequence of latitude and longitude coordinates. The field version utilizes a map-based point and click/drag interface to generate individual or a sequence of evenly spaced instrument measurements.

  16. Measuring the off axis magnetic field within a Helmholtz Coil

    NASA Astrophysics Data System (ADS)

    Pluhar, Edward; Martell, Eric

    2013-03-01

    Helmholtz coils are used because they produce nearly uniform magnetic fields on-axis. Prior research, namely Graf's thin coil experiment [The Physics Teacher, pp. 360 (2012)], has accurately measured the axial magnetic field produced by a thin coil; however, the magnetic field off-axis is known to be significantly more complicated and cannot be calculated analytically. In this research, I have numerically determined the magnetic field off-axis in the region between the two coils and compared those calculations with measured values. I then determined the effect the deviation from uniformity has on the behavior of a charged particle moving through this region, such as in the well-known electron charge-to-mass ratio experiment.

  17. An algorithm to estimate unsteady and quasi-steady pressure fields from velocity field measurements.

    PubMed

    Dabiri, John O; Bose, Sanjeeb; Gemmell, Brad J; Colin, Sean P; Costello, John H

    2014-02-01

    We describe and characterize a method for estimating the pressure field corresponding to velocity field measurements such as those obtained by using particle image velocimetry. The pressure gradient is estimated from a time series of velocity fields for unsteady calculations or from a single velocity field for quasi-steady calculations. The corresponding pressure field is determined based on median polling of several integration paths through the pressure gradient field in order to reduce the effect of measurement errors that accumulate along individual integration paths. Integration paths are restricted to the nodes of the measured velocity field, thereby eliminating the need for measurement interpolation during this step and significantly reducing the computational cost of the algorithm relative to previous approaches. The method is validated by using numerically simulated flow past a stationary, two-dimensional bluff body and a computational model of a three-dimensional, self-propelled anguilliform swimmer to study the effects of spatial and temporal resolution, domain size, signal-to-noise ratio and out-of-plane effects. Particle image velocimetry measurements of a freely swimming jellyfish medusa and a freely swimming lamprey are analyzed using the method to demonstrate the efficacy of the approach when applied to empirical data. PMID:24115059

  18. Magnetic field calculation and measurement of active magnetic bearings

    NASA Astrophysics Data System (ADS)

    Ding, Guoping; Zhou, Zude; Hu, Yefa

    2006-11-01

    Magnetic Bearings are typical devices in which electric energy and mechanical energy convert mutually. Magnetic Field indicates the relationship between 2 of the most important parameters in a magnetic bearing - current and force. This paper presents calculation and measurement of the magnetic field distribution of a self-designed magnetic bearing. Firstly, the static Maxwell's equations of the magnetic bearing are presented and a Finite Element Analysis (FEA) is found to solve the equations and get post-process results by means of ANSYS software. Secondly, to confirm the calculation results a Lakeshore460 3-channel Gaussmeter is used to measure the magnetic flux density of the magnetic bearing in X, Y, Z directions accurately. According to the measurement data the author constructs a 3D magnetic field distribution digital model by means of MATLAB software. Thirdly, the calculation results and the measurement data are compared and analyzed; the comparing result indicates that the calculation results are consistent with the measurement data in allowable dimension variation, which means that the FEA calculation method of the magnetic bearing has high precision. Finally, it is concluded that the magnetic field calculation and measurement can accurately reflect the real magnetic distribution in the magnetic bearing and the result can guide the design and analysis of the magnetic bearing effectively.

  19. Using optical soliton stability for magnetic field measurement

    NASA Astrophysics Data System (ADS)

    Şchiopu, IonuÅ£ Romeo; ǎgulinescu, Andrei, Dr; Marinescu, Andrei

    2015-02-01

    In this paper we propose a novel optical method for measuring the circular magnetic field. In practice, many situations may appear in which there are difficulties in measuring the magnetic field, as inside coils, motors etc., where the magnetic field lines are circular or elliptical. The proposed method, applied for measuring the current on high voltage lines, strongly benefits from the advantages that it offers as compared to classical solutions based on the inductive principle. Some of the advantages of optoelectronic and optic measurement methods have a real importance. These advantages consist in: avoiding the use of energy intensive materials (Cu, Fe etc.), reducing the weight of the measuring system, reducing at the minimum the fire danger due to the use of paper-oil insulation in high voltage devices etc. The novelty of our proposed method consists in using the electromagnetic radiation in ultrashort pulses, having a relatively large frequency band and a much improved resistance to external perturbations, for measuring the circular magnetic field generated from the current of high voltage lines, inside power transformers or high power motors.

  20. Measuring Magnetic Fields in Photoionized Interstellar Plasmas (HII Regions)

    NASA Astrophysics Data System (ADS)

    Spangler, Steven; Costa, Allison

    2015-11-01

    Hot luminous stars photoionize the interstellar gas around them, creating plasmas with a very high ionization fraction. In astronomical terminology, these are called HII regions. They are dynamic plasmas, expanding due to overpressure with respect to the interstellar medium. We are making diagnostic measurements to determine the strength and structure of magnetic fields in these objects. This paper presents our results on the Rosette Nebula. We diagnose the magnetic field in the Rosette by measurements of Faraday rotation on lines of sight passing through the nebula. These measurements are made with the Very Large Array radio telescope of the National Radio Astronomy Observatory. We have measurements of the rotation measure for 18 lines of sight. Values of the mean, line of sight component of the magnetic field range from about 3 to 5 microGauss. We will discuss comparison of these measurements with models for modification of the interstellar magnetic field by an HII region. This work was supported by grants AST09-07911 and ATM09-56901 from the National Science Foundation.

  1. Extension of laboratory-measured soil spectra to field conditions

    NASA Technical Reports Server (NTRS)

    Stoner, E. R.; Baumgardner, M. F.; Weismiller, R. A.; Biehl, L. L.; Robinson, B. F.

    1982-01-01

    Spectral responses of two glaciated soils, Chalmers silty clay loam and Fincastle silt loam, formed under prairie grass and forest vegetation, respectively, were measured in the laboratory under controlled moisture equilibria using an Exotech Model 20C spectroradiometer to obtain spectral data in the laboratory under artificial illumination. The same spectroradiometer was used outdoors under solar illumination to obtain spectral response from dry and moistened field plots with and without corn residue cover, representing the two different soils. Results indicate that laboratory-measured spectra of moist soil are directly proportional to the spectral response of that same field-measured moist bare soil over the 0.52 micrometer to 1.75 micrometer wavelength range. The magnitudes of difference in spectral response between identically treated Chalmers and Fincastle soils are greatest in the 0.6 micrometers to 0.8 micrometer transition region between the visible and near infrared, regardless of field condition or laboratory preparation studied.

  2. Laboratory and field measurements and evaluations of vibration at the handles of riveting hammers

    PubMed Central

    McDOWELL, THOMAS W.; WARREN, CHRISTOPHER; WELCOME, DANIEL E.; DONG, REN G.

    2015-01-01

    The use of riveting hammers can expose workers to harmful levels of hand-transmitted vibration (HTV). As a part of efforts to reduce HTV exposures through tool selection, the primary objective of this study was to evaluate the applicability of a standardized laboratory-based riveting hammer assessment protocol for screening riveting hammers. The second objective was to characterize the vibration emissions of reduced vibration riveting hammers and to make approximations of the HTV exposures of workers operating these tools in actual work tasks. Eight pneumatic riveting hammers were selected for the study. They were first assessed in a laboratory using the standardized method for measuring vibration emissions at the tool handle. The tools were then further assessed under actual working conditions during three aircraft sheet metal riveting tasks. Although the average vibration magnitudes of the riveting hammers measured in the laboratory test were considerably different from those measured in the field study, the rank orders of the tools determined via these tests were fairly consistent, especially for the lower vibration tools. This study identified four tools that consistently exhibited lower frequency-weighted and unweighted accelerations in both the laboratory and workplace evaluations. These observations suggest that the standardized riveting hammer test is acceptable for identifying tools that could be expected to exhibit lower vibrations in workplace environments. However, the large differences between the accelerations measured in the laboratory and field suggest that the standardized laboratory-based tool assessment is not suitable for estimating workplace riveting hammer HTV exposures. Based on the frequency-weighted accelerations measured at the tool handles during the three work tasks, the sheet metal mechanics assigned to these tasks at the studied workplace are unlikely to exceed the daily vibration exposure action value (2.5 m s−2) using any of the

  3. Electron Density Measurements of a Field-Reversed Configuration Using Fiber Probe Interferometry

    NASA Astrophysics Data System (ADS)

    Camacho, J. F.; Lynn, A. G.; Ruden, E. L.

    2010-11-01

    A HeNe laser interferometer operating at 632.8 nm with two single-mode optical fiber probe beams has been assembled to measure time history of the line-integrated electron density of a field-reversed configuration (FRC) for a magnetized target fusion (MTF) experiment. Our system features probe path lengths many times longer than the reference paths. We have performed simultaneous measurements along two diameters at different axial locations. During plasma formation, translation, and capture tests, the lower probe monitored the formation region, while the upper probe monitored the capture region corresponding to the location of an imploding cylindrical aluminum liner driven by the Shiva Star capacitor bank to compress and heat the FRC plasma. For the actual imploding liner experiment, the upper chord was moved to monitor the translating FRC at the entrance to the liner region. Results from the formation, translation, and capture tests as well as an actual imploding liner experiment will be presented. In addition, interferometer visibility measurements and other factors establishing the viability of our design will be discussed.

  4. In Situ Magnetic Field Measurement using the Hanle Effect

    NASA Astrophysics Data System (ADS)

    Jackson, Jarom; Durfee, Dallin

    2016-05-01

    We have developed a simple method of in situ magnetic field mapping near zero points in magnetic fields. It is ideal for measuring trapping parameters such the field gradient and curvature, and should be applicable in most experiments with a magneto-optical trap (MOT) or similar setup. This method works by probing atomic transitions in a vacuum, and is based on the Hanle effect, which alters the polarization of spontaneous emission in the presence of a magnetic field. Unlike most techniques based on the Hanle effect, however, we look only at intensity. Instead of measuring polarization we use the change in directional radiation patterns caused by a magnetic field. Using one of the cooling beams for our MOT, along with a linear polarizer, a narrow slit, and an inexpensive webcam, we measure the three dimensional position of a magnetic field zero point within our vacuum to within +/-1 mm and the gradient through the zero point to an accuracy of 4%. This work was supported by NSF Grant Number PHY-1205736.

  5. Detection of reflector surface from near field phase measurements

    NASA Technical Reports Server (NTRS)

    Ida, Nathan

    1991-01-01

    The deviation of a reflector antenna surface from a perfect parabolic shape causes degradation of the performance of the antenna. The problem of determining the shape of the reflector surface in a reflector antenna using near field phase measurements is not a new one. A recent issue of the IEEE tansactions on Antennas and Propagation (June 1988) contained numerous descriptions of the use of these measurements: holographic reconstruction or inverse Fourier transform. Holographic reconstruction makes use of measurement of the far field of the reflector and then applies the Fourier transform relationship between the far field and the current distribution on the reflector surface. Inverse Fourier transformation uses the phase measurements to determine the far field pattern using the method of Kerns. After the far field pattern is established, an inverse Fourier transform is used to determine the phases in a plane between the reflector surface and the plane in which the near field measurements were taken. These calculations are time consuming since they involve a relatively large number of operations. A much faster method can be used to determine the position of the reflector. This method makes use of simple geometric optics to determine the path length of the ray from the feed to the reflector and from the reflector to the measurement point. For small physical objects and low frequencies, diffraction effects have a major effect on the error, and the algorithm provides incorrect results. It is believed that the effect is less noticeable for large distortions such as antenna warping, and more noticeable for small, localized distortions such as bumps and depressions such as might be caused by impact damage.

  6. The FORS1 catalogue of stellar magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Bagnulo, S.; Fossati, L.; Landstreet, J. D.; Izzo, C.

    2015-11-01

    Context. The FORS1 instrument on the ESO Very Large Telescope was used to obtain low-resolution circular polarised spectra of nearly a thousand different stars, with the aim of measuring their mean longitudinal magnetic fields. Magnetic fields were measured by different authors, and using different methods and software tools. Aims: A catalogue of FORS1 magnetic measurements would provide a valuable resource with which to better understand the strengths and limitations of this instrument and of similar low-dispersion, Cassegrain spectropolarimeters. However, FORS1 data reduction has been carried out by a number of different groups using a variety of reduction and analysis techniques. Our understanding of the instrument and our data reduction techniques have both improved over time. A full re-analysis of FORS1 archive data using a consistent and fully documented algorithm would optimise the accuracy and usefulness of a catalogue of field measurements. Methods: Based on the ESO FORS pipeline, we have developed a semi-automatic procedure for magnetic field determinations, which includes self-consistent checks for field detection reliability. We have applied our procedure to the full content of circular spectropolarimetric measurements of the FORS1 archive. Results: We have produced a catalogue of spectro-polarimetric observations and magnetic field measurements for ~1400 observations of ~850 different objects. The spectral type of each object has been approximately classified. We have also been able to test different methods for data reduction is a systematic way. The resulting catalogue has been used to produce an estimator for an upper limit to the uncertainty in a field strength measurement of an early type star as a function of the signal-to-noise ratio of the observation. Conclusions: While FORS1 is not necessarily an optimal instrument for the discovery of weak magnetic fields, it is very useful for the systematic study of larger fields, such as those found in Ap

  7. Measurement, comparison, and transformation of dynamic magnetization in pulse field and high-frequency alternating field

    NASA Astrophysics Data System (ADS)

    Kodama, K.

    2015-12-01

    Dynamic magnetizations of selected natural samples (sediments and volcanic rocks) were measured in time domain as well as in frequency domain. The time domain measurements were performed in pulse fields with variable lengths (10 μs to 10 ms) and amplitudes (0.5 mT to 0.7 T). To measure hysteresis parameters for small loops, one cycle of positive and negative pulses with different rate of field variation were generated. In the frequency domain, low-field magnetic susceptibility was measured over the frequency rage (1 kHz to 500 kHz) corresponding to the pulse lengths in the time domain measurements. Results in the time domain were characterized by the transient magnetization-field curves that were broadly comparable to the corresponding portions of the hysteresis loops measured by a quasi-static method using a VSM. The dynamic coercivity that is defined as the intersect with the abscissa in the negative regime increased as the pulse length reduced and the pulse peak increased. In strong pulse fields (> 0.5 T), irrespective of the kinds of samples, the magnetization remained at the end of a pulse and decayed exponentially within a few ms, suggesting rapid magnetic relaxations. In weak pulse fields, no such relaxation was observed except for the sediments rich in superparamagnetic (SP) particles. These field dependencies suggest that the relaxations in the strong fields could be due to the dynamics of the domain walls in the MD particles, while those of the sediments in weak fields may be ascribed to the relaxation of the SP particles. Results in the frequency domain were obtained in terms of the frequency spectrum of the real and imaginary components of complex susceptibility. Comparisons and interpretations of the data in these different domains were made in terms of the distribution of relaxation times. Discussions on the numerical conversion and transformation of these data as well as their rock magnetic applications will be provided.

  8. Post-measurement bipartite entanglement entropy in conformal field theories

    NASA Astrophysics Data System (ADS)

    Rajabpour, M. A.

    2015-08-01

    We derive exact formulas for bipartite von Neumann entanglement entropy after partial projective local measurement in (1 +1 ) -dimensional conformal field theories with periodic and open boundary conditions. After defining the setup we will check numerically the validity of our results in the case of Klein-Gordon field theory (coupled harmonic oscillators) and spin-1 /2 X X chain in a magnetic field. The agreement between analytical results and the numerical calculations is very good. We also find a lower bound for localizable entanglement in coupled harmonic oscillators.

  9. Measurements of lunar magnetic field interaction with the solar wind.

    NASA Technical Reports Server (NTRS)

    Dyal, P.; Parkin, C. W.; Snyder, C. W.; Clay, D. R.

    1972-01-01

    Study of the compression of the remanent lunar magnetic field by the solar wind, based on measurements of remanent magnetic fields at four Apollo landing sites and of the solar wind at two of these sites. Available data show that the remanent magnetic field at the lunar surface is compressed as much as 40% above its initial value by the solar wind, but the total remanent magnetic pressure is less than the stagnation pressure by a factor of six, implying that a local shock is not formed.

  10. Estimating of pulsed electric fields using optical measurements.

    SciTech Connect

    Flanagan, Timothy McGuire; Chantler, Gary R.

    2013-09-01

    We performed optical electric field measurements ion nanosecond time scales using the electrooptic crystal beta barium borate (BBO). Tests were based on a preliminary bench top design intended to be a proofofprinciple stepping stone towards a modulardesign optical Efield diagnostic that has no metal in the interrogated environment. The long term goal is to field a modular version of the diagnostic in experiments on large scale xray source facilities, or similarly harsh environments.

  11. New interpretations of measured antihydrogen velocities and field ionization spectra.

    PubMed

    Pohl, T; Sadeghpour, H R; Gabrielse, G

    2006-10-01

    We present extensive Monte Carlo simulations, showing that cold antihydrogen (H) atoms are produced when antiprotons (p) are gently heated in the side wells of a nested Penning trap. The observed H with high energies, that had seemed to indicate otherwise, are instead explained by a surprisingly effective charge-exchange mechanism. We shed light on the previously measured field-ionization spectrum, and reproduce both the characteristic low-field power law as well as the enhanced H production at higher fields. The latter feature is shown to arise from H toms too deeply bound to be described as guiding center atoms, atoms with internally chaotic motion. PMID:17155247

  12. Radiated electric field measurements in U.S. Army helicopters.

    PubMed

    Bruckart, J E

    1992-11-01

    Aircraft systems and medical devices generate electromagnetic fields. Electromagnetic interference (EMI) can cause faulty operation of aircraft systems or medical devices and endanger patients or aircraft crewmembers. A ground and inflight study was conducted to describe the electromagnetic fields in typical operations. Broadband isotropic field sensors measured electric fields from 5 kHz to 3 MHz, 3 to 500 MHz, and 0.5 MHz to 6 GHz. Fields were measured at 0.5 m space intervals in JOH-58A, JUH-1H, and JUH-60A helicopters with systems off, operating RPM, 5-ft hover, 50-ft hover, and cruise. Electric fields in the environment were homogeneous and less than 0.1 V/m. Fields in the helicopters increased during ascent, but remained less than 2 V/m except during radio transmissions. EMI effect of the Physio Control Lifepack 8 was demonstrated during FM radio transmission. The results are useful in evaluating electromagnetic emissions and predicting operations that may result in an inflight malfunction of a medical device or aircraft system. PMID:1445153

  13. Radiated electric field measurements in U.S. Army helicopters

    NASA Astrophysics Data System (ADS)

    Bruckart, James E.

    1992-11-01

    Aircraft systems and medical devices generate electromagnetic fields. EMI can cause faulty operation of aircraft systems or medical devices and endanger patients or aircraft crewmembers. A ground and inflight study was conducted to describe the electromagnetic fields in typical operations. Broadband isotropic field sensors measured electric fields from 5 kHz to 3 MHz, 3 to 500 MHz, and 0.5 MHz to 6 GHz. Fields were measured at 0.5 m space intervals in JOH-58A, JUH-1H, and JUH-60A helicopters with systems off, operating RPM, 5-ft hover, 50-ft hover, and cruise. Electric fields in the environment were homogeneous and less than 0.1 V/m. Fields in the helicopters increased during ascent, but remained less than 2 V/m except during radio transmissions. EMI effect of the Physio Control Lifepack 8 was demonstrated during FM radio transmission. The results are useful in evaluating electromagnetic emissions and predicting operations that may result in an inflight malfunction of a medical device or aircraft system.

  14. High-latitude dayside electric field and particle measurements

    NASA Technical Reports Server (NTRS)

    Maynard, N. C.; Johnstone, A. D.

    1973-01-01

    Two rockets carrying electric field and low energy particle instrumentation were launched near noon at 80 deg magnetic latitude. One flight encountered polar cap conditions only while the other traversed part of the polar cusp. Although weak particle precipitation was measured on both flights, bursts of intense magnetosheath-type electron fluxes were detected on the latter. Strong electric fields such as would result from anti-sunward convection were observed during both flights. The measurements are compared with results obtained by other types of space craft and interpreted in the light of those data.

  15. Magnetic diode for measurement of magnetic-field strength

    SciTech Connect

    Fedotov, S.I.; Zalkind, V.M.

    1988-02-01

    The accuracy of fabrication and assembly of the elements of the magnetic systems of thermonuclear installations of the stellarator type is checked by study of the topography of the confining magnetic field and is determined by the space resolution and accuracy of the measuring apparatus. A magnetometer with a galvanomagnetic sensor is described that is used to adjust the magnetic system of the Uragan-3 stellarator. The magnetometer measure magnetic-field induction in the range of 6 x 10/sup -7/-10/sup -2/ T with high space resolution.

  16. Near field optical probe for critical dimension measurements

    DOEpatents

    Stallard, Brian R.; Kaushik, Sumanth

    1999-01-01

    A resonant planar optical waveguide probe for measuring critical dimensions on an object in the range of 100 nm and below. The optical waveguide includes a central resonant cavity flanked by Bragg reflector layers with input and output means at either end. Light is supplied by a narrow bandwidth laser source. Light resonating in the cavity creates an evanescent electrical field. The object with the structures to be measured is translated past the resonant cavity. The refractive index contrasts presented by the structures perturb the field and cause variations in the intensity of the light in the cavity. The topography of the structures is determined from these variations.

  17. Near field optical probe for critical dimension measurements

    DOEpatents

    Stallard, B.R.; Kaushik, S.

    1999-05-18

    A resonant planar optical waveguide probe for measuring critical dimensions on an object in the range of 100 nm and below is disclosed. The optical waveguide includes a central resonant cavity flanked by Bragg reflector layers with input and output means at either end. Light is supplied by a narrow bandwidth laser source. Light resonating in the cavity creates an evanescent electrical field. The object with the structures to be measured is translated past the resonant cavity. The refractive index contrasts presented by the structures perturb the field and cause variations in the intensity of the light in the cavity. The topography of the structures is determined from these variations. 8 figs.

  18. Electric Field Double Probe Measurements for Ionospheric Space Plasma Experiments

    NASA Technical Reports Server (NTRS)

    Pfaff, R.

    1999-01-01

    Double probes represent a well-proven technique for gathering high quality DC and AC electric field measurements in a variety of space plasma regimes including the magnetosphere, ionosphere, and mesosphere. Such experiments have been successfully flown on a variety of spacecraft including sounding rockets and satellites. Typical instrument designs involve a series of trades, depending on the science objectives, type of platform (e.g., spinning or 3-axis stabilized), expected plasma regime where the measurements will be made, available telemetry, budget, etc. In general, ionospheric DC electric field instruments that achieve accuracies of 0.1 mV/m or better, place spherical sensors at large distances (10m or more) from the spacecraft body in order to extend well beyond the spacecraft wake and sheath and to achieve large signal-to-noise ratios for DC and long wavelength measurements. Additional sets of sensors inboard of the primary, outermost sensors provide useful additional information, both for diagnostics of the plasma contact potentials, which particularly enhance the DC electric field measurements on non-spinning spacecraft, and for wavelength and phase velocity measurements that use the spaced receiver or "interferometer" technique. Accurate attitude knowledge enables B times V contributions to be subtracted from the measured potentials, and permits the measured components to be rotated into meaningful geophysical reference frames. We review the measurement technique for both DC and wave electric field measurements in the ionosphere discussing recent advances involving high resolution burst memories, multiple baseline double probes, new sensor surface materials, biasing techniques, and other considerations.

  19. Micro analysis of fringe field formed inside LDA measuring volume

    NASA Astrophysics Data System (ADS)

    Ghosh, Abhijit; Nirala, A. K.

    2016-05-01

    In the present study we propose a technique for micro analysis of fringe field formed inside laser Doppler anemometry (LDA) measuring volume. Detailed knowledge of the fringe field obtained by this technique allows beam quality, alignment and fringe uniformity to be evaluated with greater precision and may be helpful for selection of an appropriate optical element for LDA system operation. A complete characterization of fringes formed at the measurement volume using conventional, as well as holographic optical elements, is presented. Results indicate the qualitative, as well as quantitative, improvement of fringes formed at the measurement volume by holographic optical elements. Hence, use of holographic optical elements in LDA systems may be advantageous for improving accuracy in the measurement.

  20. Work function measurements by the field emission retarding potential method.

    NASA Technical Reports Server (NTRS)

    Strayer, R. W.; Mackie, W.; Swanson, L. W.

    1973-01-01

    Description of the theoretical foundation of the field electron retarding potential method, and review of its experimental application to the measurement of single crystal face work functions. The results obtained from several substrates are discussed. An interesting and useful fallout from the experimental approach described is the ability to accurately measure the elastic and inelastic reflection coefficient for impinging electrons to near zero-volt energy.

  1. Planetary science. Low-altitude magnetic field measurements by MESSENGER reveal Mercury's ancient crustal field.

    PubMed

    Johnson, Catherine L; Phillips, Roger J; Purucker, Michael E; Anderson, Brian J; Byrne, Paul K; Denevi, Brett W; Feinberg, Joshua M; Hauck, Steven A; Head, James W; Korth, Haje; James, Peter B; Mazarico, Erwan; Neumann, Gregory A; Philpott, Lydia C; Siegler, Matthew A; Tsyganenko, Nikolai A; Solomon, Sean C

    2015-05-22

    Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury's crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury's history. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust inferred from MESSENGER elemental composition data. PMID:25953822

  2. Vertical Electric Field Measurements with Copper Plates by Sounding Balloon

    NASA Astrophysics Data System (ADS)

    Wen, Shao-Chun; Chiu, Cheng-Hsiu; Bing-Chih Chen, Alfred; Hsu, Rue-Ron; Su, Han-Tzong

    2015-04-01

    The vertical electric field plays an important role in driving the circulation of the global electric circuit, and crucial to the formation of the transient luminous events (TLEs). The in-situ measurement of the electric field in the upper atmosphere, especially from cloud top to the bottom of the ionosphere is very challenging but essential. Limited by the flight vehicle, the measurements of the electric field in and above cloud, especiall thundercloud, is rare up to now. A light-weight electric field meter was developed independently and sent to 30 km height by small meteorological balloons successfully. Other than the existing long-spaced, spherical probe design, an improved electric field meter has been built and tested carefully. A new circuit with ultra high input impedance and a high voltage amplifier is implemented to reduce the AC noise induced by the voltage divider. Two copper plates are used to replace the double spherical probes which is spaced by a long fiberglass boom. The in-lab calibration and tests show that this new model is superior to the existing design and very sensitive to the variation of the DC electric field. In this poster, the design and the in-lab tests will be presented, and preliminary results of the flight experiments are also discussed.

  3. LIDAR Wind Speed Measurements of Evolving Wind Fields

    SciTech Connect

    Simley, E.; Pao, L. Y.

    2012-07-01

    Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed Taylor's frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations to create a more realistic measurement model. A simple model of wind evolution is applied to a frozen wind field used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements are also evaluated with a large eddy simulation of a stable boundary layer provided by the National Center for Atmospheric Research. Simulation results show the combined effects of LIDAR errors and wind evolution for realistic turbine-mounted LIDAR measurement scenarios.

  4. Electric field vector measurements in a surface ionization wave discharge

    NASA Astrophysics Data System (ADS)

    Goldberg, Benjamin M.; Böhm, Patrick S.; Czarnetzki, Uwe; Adamovich, Igor V.; Lempert, Walter R.

    2015-10-01

    This work presents the results of time-resolved electric field vector measurements in a short pulse duration (60 ns full width at half maximum), surface ionization wave discharge in hydrogen using a picosecond four-wave mixing technique. Electric field vector components are measured separately, using pump and Stokes beams linearly polarized in the horizontal and vertical planes, and a polarizer placed in front of the infrared detector. The time-resolved electric field vector is measured at three different locations across the discharge gap, and for three different heights above the alumina ceramic dielectric surface, ~100, 600, and 1100 μm (total of nine different locations). The results show that after breakdown, the discharge develops as an ionization wave propagating along the dielectric surface at an average speed of 1 mm ns-1. The surface ionization wave forms near the high voltage electrode, close to the dielectric surface (~100 μm). The wave front is characterized by significant overshoot of both vertical and horizontal electric field vector components. Behind the wave front, the vertical field component is rapidly reduced. As the wave propagates along the dielectric surface, it also extends further away from the dielectric surface, up to ~1 mm near the grounded electrode. The horizontal field component behind the wave front remains quite significant, to sustain the electron current toward the high voltage electrode. After the wave reaches the grounded electrode, the horizontal field component experiences a secondary rise in the quasi-dc discharge, where it sustains the current along the near-surface plasma sheet. The measurement results indicate presence of a cathode layer formed near the grounded electrode with significant cathode voltage fall, ≈3 kV, due to high current density in the discharge. The peak reduced electric field in the surface ionization wave is 85-95 Td, consistent with dc breakdown field estimated from the Paschen curve for

  5. How People Actually Use Thermostats

    SciTech Connect

    Meier, Alan; Aragon, Cecilia; Hurwitz, Becky; Mujumdar, Dhawal; Peffer, Therese; Perry, Daniel; Pritoni, Marco

    2010-08-15

    Residential thermostats have been a key element in controlling heating and cooling systems for over sixty years. However, today's modern programmable thermostats (PTs) are complicated and difficult for users to understand, leading to errors in operation and wasted energy. Four separate tests of usability were conducted in preparation for a larger study. These tests included personal interviews, an on-line survey, photographing actual thermostat settings, and measurements of ability to accomplish four tasks related to effective use of a PT. The interviews revealed that many occupants used the PT as an on-off switch and most demonstrated little knowledge of how to operate it. The on-line survey found that 89% of the respondents rarely or never used the PT to set a weekday or weekend program. The photographic survey (in low income homes) found that only 30% of the PTs were actually programmed. In the usability test, we found that we could quantify the difference in usability of two PTs as measured in time to accomplish tasks. Users accomplished the tasks in consistently shorter times with the touchscreen unit than with buttons. None of these studies are representative of the entire population of users but, together, they illustrate the importance of improving user interfaces in PTs.

  6. Functional Measurement in the Field of Empirical Bioethics

    ERIC Educational Resources Information Center

    Mullet, Etienne; Sorum, Paul C.; Teysseire, Nathalie; Nann, Stephanie; Martinez, Guadalupe Elizabeth Morales; Ahmed, Ramadan; Kamble, Shanmukh; Olivari, Cecilia; Sastre, Maria Teresa Munoz

    2012-01-01

    We present, in a synthetic way, some of the main findings from five studies that were conducted in the field of empirical bioethics, using the Functional Measurement framework. These studies were about (a) the rationing of rare treatments, (b) adolescents' abortions, (c) end-of-life decision-making regarding damaged neonates, (d) end-of-life…

  7. Thermoelectrically cooled interband cascade laser for field measurements

    NASA Astrophysics Data System (ADS)

    Christensen, Lance E.; Mansour, Kamjou; Yang, Rui Q.

    2010-11-01

    The development of interband cascade lasers from concept to packaged devices is briefly reviewed. The application of a single-mode, mid-IR (3.27-μm) interband cascade laser packaged with a thermoelectric cooler for field measurements of methane and water is described.

  8. Simple System to Measure the Earth's Magnetic Field

    ERIC Educational Resources Information Center

    Akoglu, R.; Halilsoy, M.; Mazharimousavi, S. Habib

    2010-01-01

    Our aim in this proposal is to use Faraday's law of induction as a simple lecture demonstration to measure the Earths magnetic field (B). This will also enable the students to learn about how electric power is generated from rotational motion. Obviously the idea is not original, yet it may be attractive in the sense that no sophisticated devices…

  9. CONVECTIVE DIFFUSION FIELD MEASUREMENTS COMPARED WITH LABORATORY AND NUMERICAL EXPERIMENTS

    EPA Science Inventory

    Some of the more fundamental diffusion parameters measured in the CONDORS convective diffusion field experiment are compared with laboratory experiment and numerical modeling results by means of nondimensionalizations using convective scaling (i.e., mixing depth, z sub i, for len...

  10. Lidar Based Particulate Flux Measurements of Agricultural Field

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A three-wavelength portable scanning lidar system was developed to derive information on particulate spatial aerosol distribution over remote distances. The lidar system and retrieval approach has been tested during several field campaigns measuring agricultural emissions from a swine feeding operat...

  11. Triggering for Magnetic Field Measurements of the LCLS Undulators

    SciTech Connect

    Hacker, Kirsten

    2010-12-13

    A triggering system for magnetic field measurements of the LCLS undulators has been built with a National Instruments PXI-1002 and a Xylinx FPGA board. The system generates single triggers at specified positions, regardless of encoder sensor jitter about a linear scale.

  12. NITRIC ACID SHOOTOUT: FIELD COMPARISON OF MEASUREMENT METHODS (JOURNAL VERSION)

    EPA Science Inventory

    Eighteen instruments for measuring atmospheric concentrations of nitric acid were compared in an eight-day field study at Pomona College, situated in the eastern portion of the Los Angeles Basin, in September 1985. The study design included collocated and separated duplicate samp...

  13. Preliminary field measurement of cotton fiber micronaire by portable NIR

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The decline of the U.S. textile industry has led to the dramatic increase in the export of U.S. cotton. Improved quality measurement systems are needed to successfully compete in the global marketplace. One key need is the development of new breeder/producer quality tools for field and at-line mea...

  14. Sub-micronewton thrust measurements of indium field emission thrusters

    NASA Technical Reports Server (NTRS)

    Ziemer, J. K.

    2003-01-01

    The performance of three indium field emission thrusters (In-FETs) developed by the Austrian Research Center Seibersdorf (ARCS) have been measured up to 200 muN, 2 mA, and 20 W using a submicronewton resolution thrust stand.

  15. Work function measurements by the field emission retarding potential method

    NASA Technical Reports Server (NTRS)

    Swanson, L. W.; Strayer, R. W.; Mackie, W. A.

    1971-01-01

    Using the field emission retarding potential method true work functions have been measured for the following monocrystalline substrates: W(110), W(111), W(100), Nb(100), Ni(100), Cu(100), Ir(110) and Ir(111). The electron elastic and inelastic reflection coefficients from several of these surfaces have also been examined near zero primary beam energy.

  16. Microspacecraft and Earth observation: Electrical Field (ELF) measurement project

    NASA Technical Reports Server (NTRS)

    1990-01-01

    There is a need for an inexpensive, extensive, long-lasting global electric field measurement system (ELF). The primary performance driver of this mission is the need to measure the attitude of each spacecraft in the Earth's electric field very accurately. In addition, it is necessary to know the electric charge generated by the satellite as it crosses the magnetic field lines (E equals V times B). In order to achieve the desired global coverage, a constellation of about 50 satellites in at least 18 different orbits will be used. To reduce the cost of each satellite, off-the-shelf, proven technology will be used whenever possible. Researchers have set a limit of $500,000 per satellite. Researchers expect the program cost, including the deployment of the entire constellation, to be less than $100 million. The minimum projected mission life is five years.

  17. Global ionospheric electric field measurements in April 1978

    NASA Technical Reports Server (NTRS)

    Holzworth, R.; Kishi, A.; Wygant, J.; Mozer, F.; Gonzales, C.; Greenwald, R.; Blanc, M.; Vickrey, J.

    1981-01-01

    This paper presents an introduction to a global campaign of simultaneous quasi-static electric field measurements from radars, balloons, and satellites at various places within the earth's environment for April 8-14, 1978. The 7-day time period encompassed both extended magnetically quiet times as well as two magnetic storms. These storms were related to SSCs that followed solar flares, one of which included a day-long solar proton event. The wide variety of instrumentation and associated operating modes involved in this campaign is described. Sample conjunctions between satellites and ionospheric measurements are shown that demonstrate that field line mapping is valid under certain circumstances. Some of the largest ionospheric electric fields ever reported with greater than 100-km scale size occurred on April 11, and these events are discussed in detail.

  18. Electromagnetic Near Field Measurements of Two Critical Assemblies

    NASA Astrophysics Data System (ADS)

    Goettee, Jeffrey; Goorley, Tim; Mayo, Douglas; Myers, William; Goda, Joetta; Sage, Frank

    2015-04-01

    Preliminary measurements of the fast metal nuclear reactors at the National Criticality Experiments Research Center (NCERC) and at White Sands Missile Range (WSMR) within the past year characterize the very near field environment of these critical assemblies. Both reactors are fast, highly enriched uranium metal reactors and can be operated in a burst mode above prompt supercritical. Initial measurements of the electric and the magnetic fields within the reactor cell are consistent between the two facilities, and begin to describe the dependance on distance and polarization as might be assumed from initial Monte Carlo modelling of these facilities. The amplitude and time variation of the electric and magnetic fields are consistent with burst time scales. The polarization is consistent with the geometry of the source and with Compton scattering from fission gammas as the dominant ionization mechanism. An overview of the two fast neutron sources and the excursion dynamics, the experimental details, and summary of the modelling calculations will be provided as background.

  19. Localized strain field measurement on laminography data with mechanical regularization

    NASA Astrophysics Data System (ADS)

    Taillandier-Thomas, Thibault; Roux, Stéphane; Morgeneyer, Thilo F.; Hild, François

    2014-04-01

    For an in-depth understanding of the failure of structural materials the study of deformation mechanisms in the material bulk is fundamental. In situ synchrotron computed laminography provides 3D images of sheet samples and digital volume correlation yields the displacement and strain fields between each step of experimental loading by using the natural contrast of the material. Difficulties arise from the lack of data, which is intrinsic to laminography and leads to several artifacts, and the little absorption contrast in the 3D image texture of the studied aluminum alloy. To lower the uncertainty level and to have a better mechanical admissibility of the measured displacement field, a regularized digital volume correlation procedure is introduced and applied to measure localized displacement and strain fields.

  20. Field Measurements of Reynolds Stress near a Riverbank

    USGS Publications Warehouse

    Moody, J.A.; Smith, J.D.

    2002-01-01

    The Reynolds stress field was measured near the bank of the Powder River in southeastern Montana. The measurements were made from the bank using an aluminum I-beam cantilevered over the water to support a carriage system for positioning an acoustic doppler velocimeter in a vertical plane perpendicular to 1) the bank and 2) the streamwise velocity field. During quasi-steady flow at the peak (71 m3s-1) of the spring snowmelt runoff in May 1996, turbulent velocities were measured at 25 Hertz along six vertical locations spaced 0.5 m apart and within about 3.5 m of the riverbank. When the turbulent velocities are transformed to the ray-isovel coordinate system appropriate for this two-dimension problem, the turbulent characteristics near the bed are consistent with similar field measurements made by others for the one-dimensional problem of uniform flow over a horizontal bed far from lateral boundaries. The three turbulent intensities, (u???2) 1/2, (v???2)1/2 and (w??? 2)1/2, normalized by the local shear velocity, u*, were essentially constant with distance above the bed along a ray and the average values were 2.1, 1.4, and 1.2. Future turbulence measurements could be improved by measuring the streamwise flow first, then determining the approximate location of the rays and isovels so that the turbulence measurements could be made along the approximated rays rather than along verticals. In addition, to improve the possibility making turbulence measurements during steady, uniform flow, the site should be carefully selected to minimize local flow accelerations caused by spatial variability of the riverbank. Also, the measurements should be made at times when the stage is constant, no local erosion or deposition of sediment occurs, and when wind velocities are small.

  1. Electric field induced Lyman-α emission of a hydrogen beam for electric field measurements.

    PubMed

    Chérigier-Kovacic, L; Ström, P; Lejeune, A; Doveil, F

    2015-06-01

    Electric field induced Lyman-α emission is a new way of measuring weak electric fields in vacuum and in a plasma. It is based on the emission of Lyman-α radiation (121.6 nm) by a low-energy metastable H atom beam due to Stark-quenching of the 2s level induced by the field. In this paper, we describe the technique in detail. Test measurements have been performed in vacuum between two plates polarized at a controlled voltage. The intensity of emitted radiation, proportional to the square of the field modulus, has been recorded by a lock-in technique, which gives an excellent signal to noise ratio. These measurements provide an in situ calibration that can be used to obtain the absolute value of the electric field. A diagnostic of this type can help to address a long standing challenge in plasma physics, namely, the problem of measuring electric fields without disturbing the equilibrium of the system that is being studied. PMID:26133836

  2. Electric Field Measurements During the Genesis and Rapid Intensification Processes (GRIP) Field Program

    NASA Technical Reports Server (NTRS)

    Bateman, Monte G.; Blakeslee, Richard J.; Mach, Douglas M.

    2010-01-01

    During the Genesis and Rapid Intensification Processes (GRIP) field program, a system of 6 electric field mills was flown on one of NASA's Global Hawk aircraft. We placed several mills on the aircraft to enable us to measure the vector electric field. We created a distributed, ethernet-connected system so that each sensor has its own embedded Linux system, complete with web server. This makes our current generation system fully "sensor web enabled." The Global Hawk has several unique qualities, but relevant to quality storm electric field measurements are high altitude (20 km) and long duration (20-30 hours) flights. There are several aircraft participating in the GRIP program, and coordinated measurements are happening. Lightning and electric field measurements will be used to study the relationships between lightning and other storm characteristics. It has been long understood that lightning can be used as a marker for strong convective activity. Past research and field programs suggest that lightning flash rate may serve as an indicator and precursor for rapid intensification change in tropical cyclones and hurricanes. We have the opportunity to sample hurricanes for many hours at a time and observe intensification (or de-intensification) periods. The electrical properties of hurricanes during such periods are not well known. American

  3. Electric field induced Lyman-α emission of a hydrogen beam for electric field measurements

    SciTech Connect

    Chérigier-Kovacic, L. Doveil, F.; Ström, P.; Lejeune, A.

    2015-06-15

    Electric field induced Lyman-α emission is a new way of measuring weak electric fields in vacuum and in a plasma. It is based on the emission of Lyman-α radiation (121.6 nm) by a low-energy metastable H atom beam due to Stark-quenching of the 2s level induced by the field. In this paper, we describe the technique in detail. Test measurements have been performed in vacuum between two plates polarized at a controlled voltage. The intensity of emitted radiation, proportional to the square of the field modulus, has been recorded by a lock-in technique, which gives an excellent signal to noise ratio. These measurements provide an in situ calibration that can be used to obtain the absolute value of the electric field. A diagnostic of this type can help to address a long standing challenge in plasma physics, namely, the problem of measuring electric fields without disturbing the equilibrium of the system that is being studied.

  4. Mean field limit for bosons and propagation of Wigner measures

    NASA Astrophysics Data System (ADS)

    Ammari, Z.; Nier, F.

    2009-04-01

    We consider the N-body Schrödinger dynamics of bosons in the mean field limit with a bounded pair-interaction potential. According to the previous work [Ammari, Z. and Nier, F., "Mean field limit for bosons and infinite dimensional phase-space analysis," Ann. Henri Poincare 9, 1503 (2008)], the mean field limit is translated into a semiclassical problem with a small parameter ɛ →0, after introducing an ɛ-dependent bosonic quantization. The limits of quantum correlation functions are expressed as a push forward by a nonlinear flow (e.g., Hartree) of the associated Wigner measures. These object and their basic properties were introduced by Ammari and Nier in the infinite dimensional setting. The additional result presented here states that the transport by the nonlinear flow holds for a rather general class of quantum states in their mean field limit.

  5. Mean field limit for bosons and propagation of Wigner measures

    SciTech Connect

    Ammari, Z.; Nier, F.

    2009-04-15

    We consider the N-body Schroedinger dynamics of bosons in the mean field limit with a bounded pair-interaction potential. According to the previous work [Ammari, Z. and Nier, F., 'Mean field limit for bosons and infinite dimensional phase-space analysis', Ann. Henri Poincare 9, 1503 (2008)], the mean field limit is translated into a semiclassical problem with a small parameter {epsilon}{yields}0, after introducing an {epsilon}-dependent bosonic quantization. The limits of quantum correlation functions are expressed as a push forward by a nonlinear flow (e.g., Hartree) of the associated Wigner measures. These object and their basic properties were introduced by Ammari and Nier in the infinite dimensional setting. The additional result presented here states that the transport by the nonlinear flow holds for a rather general class of quantum states in their mean field limit.

  6. Advanced measurements and techniques in high magnetic fields

    SciTech Connect

    Campbell, L.J.; Rickel, D.G.; Lacerda, A.H.; Kim, Y.

    1997-07-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). High magnetic fields present a unique environment for studying the electronic structure of materials. Two classes of materials were chosen for experiments at the national high Magnetic Field Laboratory at Los Alamos: highly correlated electron systems and semiconductors. Magnetotransport and thermodynamic experiments were performed on the renormalized ground states of highly correlated electron systems (such as heavy fermion materials and Kondo insulators) in the presence of magnetic fields that are large enough to disrupt the many-body correlations. A variety of optical measurements in high magnetic fields were performed on semiconductor heterostructures including GaAs/AlGaAs single heterojunctions (HEMT structure), coupled double quantum wells (CDQW), asymmetric coupled double quantum wells (ACDQW), multiple quantum wells and a CdTe single crystal thin film.

  7. Actual evapotranspiration estimation in a Mediterranean mountain region by means of Landsat-5 TM and TERRA/AQUA MODIS imagery and Sap Flow measurements in Pinus sylvestris forest stands.

    NASA Astrophysics Data System (ADS)

    Cristóbal, J.; Poyatos, R.; Ninyerola, M.; Pons, X.; Llorens, P.

    2009-04-01

    Elevation Model, obtaining an RMS less than 30 m. Radiometric correction of Landsat non-thermal bands has been done following the methodology proposed by Pons and Solé (1994) which allows to reduce the number of undesired artifacts that are due to the effects of the atmosphere or to the differential illumination which is, in turn, due to the time of the day, the location in the Earth and the relief (zones being more illuminated than others, shadows, etc). Atmospheric correction of Landsat thermal band has been carried out by means of a single-channel algorithm improvement developed by Cristóbal et al. (2009). To compute actual evapotranspiration (AET) we have used the B-Method proposed by Jakson et al. (1977) and modified by Carlson et al. (1995) and Caselles et al. (1998), based on the energy budget, that needs as an input variables net radiation (Rn) and the difference between land surface temperature (LST) and air temperature (Ta). Air temperature has been modelled by means of multiple regression analysis and GIS interpolation using ground meteorological stations. Net radiation have been computed following two approaches based on the energy balance equation using albedo, land surface temperature, air temperature and solar radiation. Both air temperature and net radiation have been modelled at a regional scale. We have compared remote sensing daily actual evapotranspiration estimates with measured canopy transpiration. Sap flux density was measured by means of Heat dissipation sensors in 12 trees per stand, sampled according to diametric distribution, corrected to account for radial patter of sap flow using the Heat Field Deformation method and then scaled-up to stand level transpiration using tree sapwood areas. Sap flow measurements are comparable with AETd as in the Scots pine stand understorey evaporation is not significant. Measurements with sap flow technique show a mean, minimum and maximum values of AETd = 2.2, 0.6 and 3.6 mm day -1, respectively (Poyatos et al

  8. Development of Field Measurement Systems for Flight Vehicle Noise

    NASA Technical Reports Server (NTRS)

    Yu, James C.; Wright, Kenneth D.; Preisser, John S.; Marcolini, Michael A.

    1999-01-01

    Field measurement of noise radiated from flight vehicles is an important element of aircraft noise research programs. At NASA Langley, a dedicated effort that spans over two decades was devoted to the development of acoustic measurement systems to support the NASA noise research programs. The new challenge for vehicle operational noise reduction through varying glide slope and flight path require noise measurement to be made over a very large area under the vehicle flight path. Such a challenge can be met through the digital remote system currently under final development at NASA Langley.

  9. Blood flow velocity vector field reconstruction from dual-beam bidirectional Doppler OCT measurements in retinal veins.

    PubMed

    Aschinger, Gerold C; Schmetterer, Leopold; Doblhoff-Dier, Veronika; Leitgeb, Rainer A; Garhöfer, Gerhard; Gröschl, Martin; Werkmeister, René M

    2015-05-01

    In this paper, we demonstrate the possibility to reconstruct the actual blood flow velocity vector field in retinal microvessels from dual-beam bidirectional Doppler optical coherence tomography measurements. First, for a better understanding of measured phase patterns, several flow situations were simulated on the basis of the known dual beam measurement geometry. We were able to extract the vector field parameters that determine the measured phase pattern, allowing for the development of an algorithm to reconstruct the velocity vector field from measured phase data. In a next step, measurements were performed at a straight vessel section and at a venous convergence; the obtained phase data were evaluated by means of the new approach. For the straight vessel section, the reconstructed flow velocity vector field yielded a parabolic flow. For the venous convergence, however, the reconstructed vector field deviated from a parabolic profile, but was in very good accordance with the simulated vector field for the given vessel geometry. The proposed algorithm allows predictions of the velocity vector field. Moreover, the algorithm is also sensitive to directional changes of the flow velocity as small as <1°, thereby offering insight in the flow characteristics of the non-Newtonian fluid blood in microvessels. PMID:26137367

  10. Blood flow velocity vector field reconstruction from dual-beam bidirectional Doppler OCT measurements in retinal veins

    PubMed Central

    Aschinger, Gerold C.; Schmetterer, Leopold; Doblhoff-Dier, Veronika; Leitgeb, Rainer A.; Garhöfer, Gerhard; Gröschl, Martin; Werkmeister, René M.

    2015-01-01

    In this paper, we demonstrate the possibility to reconstruct the actual blood flow velocity vector field in retinal microvessels from dual-beam bidirectional Doppler optical coherence tomography measurements. First, for a better understanding of measured phase patterns, several flow situations were simulated on the basis of the known dual beam measurement geometry. We were able to extract the vector field parameters that determine the measured phase pattern, allowing for the development of an algorithm to reconstruct the velocity vector field from measured phase data. In a next step, measurements were performed at a straight vessel section and at a venous convergence; the obtained phase data were evaluated by means of the new approach. For the straight vessel section, the reconstructed flow velocity vector field yielded a parabolic flow. For the venous convergence, however, the reconstructed vector field deviated from a parabolic profile, but was in very good accordance with the simulated vector field for the given vessel geometry. The proposed algorithm allows predictions of the velocity vector field. Moreover, the algorithm is also sensitive to directional changes of the flow velocity as small as <1°, thereby offering insight in the flow characteristics of the non-Newtonian fluid blood in microvessels. PMID:26137367

  11. Early results from ISEE-A electric field measurements

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.; Maynard, N. C.; Aggson, T. L.

    1978-01-01

    In the solar wind and in middle latitude regions of the magnetosphere, spacecraft sheath fields obscure the ambient field under low plasma flux conditions such that valid measurements are confined to periods of moderately intense flux. Initial results show: (1) that the DC electric field is enhanced by roughly a factor of two in a narrow region at the front, increasing B, edge of the bow shock, (2) that scale lengths for large changes in E at the subsolar magnetopause are considerably shorter than scale lengths associated with the magnetic structure of the magnetopause, and (3) that the transverse distribution of B-aligned E-fields between the outer magnetosphere and ionospheric levels must be highly complex to account for the random turbulent appearance of the magnetospheric fields and the lack of corresponding time-space variations at ionospheric levels. Spike-like, non-oscillatory, fields lasting less than 0.2 seconds are occasionally seen at the bow shock and at the magnetopause and also intermittently appear in magnetosheath and plasma sheet regions under highly variable field conditions.

  12. Aeroacoustic near-field measurements with microscale resolution

    NASA Astrophysics Data System (ADS)

    Haufe, D.; Pietzonka, S.; Schulz, A.; Bake, F.; Enghardt, L.; Czarske, J. W.; Fischer, A.

    2014-10-01

    In order to analyse aeroacoustic phenomena at near-fields, e.g. the sound-flow interaction at aircraft engine liners, measurements of the flow velocity and the acoustic particle velocity (APV) with microscale resolution are required. To this end, the APV measurement with a high spatial resolution of 10 µm was conducted by means of a laser Doppler velocity profile sensor. For validation of the APV measurements using the profile sensor in a superposed flow, a good agreement with indirect microphone measurements as a reference was achieved, up to a maximum Mach number of 0.25. Aeroacoustic measurements at a minimum distance of 350 µm to the perforation of a bias flow liner were performed using the profile sensor. As a result, acoustically induced velocity oscillations near the rim of the orifice were detected with microscale resolution. The phase-resolved oscillation field indicates vortex shedding from the perforation, which is initiated by the sound-flow interaction. Thus, it is demonstrated that the profile sensor is a valuable tool for analysing aeroacoustic phenomena at near-fields, down to the Kolmogorov scale.

  13. Magnetic field measurement techniques with heavy ion beam probes

    SciTech Connect

    Crowley, T.P.

    1988-08-01

    Spatially (0.1 cm/sup 3/) and temporally (1 ..mu..s) resolved magnetic field measurement techniques using a heavy ion beam probe as a test particle source are described. The measurement of both steady-state and time-varying fields is discussed. The plasma flux function can be determined by measuring the toroidal velocity of the beam ion in an axisymmetric device, because the canonical angular momentum of a particle, P/sub phi/ = qpsi+M..nu../sub phi/R, is conserved in an axisymmetric system. Corrections due to nonaxisymmetry can be significant in tokamaks and must be taken into account for the current profile and fluctuation measurements. The requirements and design of a toroidal velocity detector are discussed. The signals expected in experiments using the Texas Experimental Tokamak (TEXT) heavy ion beam probe with a velocity detector have been calculated, and they are at least two orders of magnitude higher than the amplifier noise for dc measurements of poloidal and ergodic magnetic limiter fields and for sawtooth and MHD oscillations. Low-level turbulence is expected to produce signals below the noise level.

  14. Magnetic field measurements near stand-alone transformer stations.

    PubMed

    Kandel, Shaiela; Hareuveny, Ronen; Yitzhak, Nir-Mordechay; Ruppin, Raphael

    2013-12-01

    Extremely low-frequency (ELF) magnetic field (MF) measurements around and above three stand-alone 22/0.4-kV transformer stations have been performed. The low-voltage (LV) cables between the transformer and the LV switchgear were found to be the major source of strong ELF MFs of limited spatial extent. The strong fields measured above the transformer stations support the assessment method, to be used in future epidemiological studies, of classifying apartments located right above the transformer stations as highly exposed to MFs. The results of the MF measurements above the ground around the transformer stations provide a basis for the assessment of the option of implementing precautionary procedures. PMID:23836796

  15. Assessing Counter-Terrorism field training with multiple behavioral measures.

    PubMed

    Spiker, V Alan; Johnston, Joan H

    2013-09-01

    Development of behavioral pattern recognition and analysis skills is an essential element of Counter-Terrorism training, particularly in the field. Three classes of behavioral measures were collected in an assessment of skill acquisition during a US Joint Forces Command-sponsored course consisting of Combat Tracking and Combat Profiling segments. Measures included situational judgment tests, structured behavioral observation checklists, and qualitative assessments of the emergence of specific knowledge-skills-attitudes over the course of the training. The paper describes statistical evidence across the three types of measures that indicate that behavioral pattern recognition and analysis skills were successfully acquired by most students (a mix of Army and civilian law enforcement personnel) during the field training exercises. Implications for broader training of these critical skills are also discussed. PMID:22818862

  16. Field Evaluation of Broadband Electrical Impedance Tomography Measurements

    NASA Astrophysics Data System (ADS)

    Kelter, M.; Huisman, J. A.; Zimmermann, E.; Treichel, A.; Kemna, A.; Vereecken, H.

    2014-12-01

    Laboratory measurements of the complex electrical conductivity in a broad frequency range (i.e. mHz to kHz) using spectral induced polarization (SIP) measurements have shown great promise to characterize important hydrological properties (e.g. hydraulic conductivity) and biogeochemical processes. However, translating these findings to field applications remains challenging, and significant improvements in spectral electrical impedance tomography (EIT) are still required to obtain images of the complex electrical conductivity with sufficient accuracy in the field. The aim of this study is to present recent improvements in the inversion and processing of broadband field EIT measurements, and to evaluate the accuracy and spectral consistency of the obtained images of the real and imaginary part of the electrical conductivity. In a first case study, time-lapse surface EIT measurements were performed during an infiltration experiment to investigate the spectral complex electrical conductivity as a function of water content. State-of-the-art data processing and inversion approaches were used to obtain images of the complex electrical conductivity in a frequency range of 100 mHz to 1 kHz, and integral parameters were obtained using Debye decomposition. Results showed consistent spectral and spatial variation of the phase of the complex electrical conductivity in a broad frequency range, and a complex dependence on water saturation that was reasonably consistent with laboratory EIT measurements. In a second case study, borehole EIT measurements were made in a well-characterized aquifer. These measurements were inverted to obtain broadband images of the complex conductivity after correction for inductive and capacitive coupling using recently developed procedures. The results showed good correspondence with reference laboratory SIP measurements in a broad frequency bandwidth up to 1 kHz only after application of the correction procedures.

  17. Methodical problems of magnetic field measurements in umbra of sunspots

    NASA Astrophysics Data System (ADS)

    Lozitska, N. I.; Lozitsky, V. G.; Andryeyeva, O. A.; Akhtemov, Z. S.; Malashchuk, V. M.; Perebeynos, V. A.; Stepanyan, N. N.; Shtertser, N. I.

    2015-02-01

    Visual measurements of magnetic field strengths in sunspot umbra provide data on magnetic field strength modulus directly, i.e., irrespective from any solar atmosphere model assumptions. In order to increase the accuracy of calculation of the solar magnetic indexes, such as B ‾ max or Bsp, the inclusion of all available data from different observatories is needed. In such measurements some methodical problems arise, which bring about inconsistency of the data samples combined from different sources; this work describes the problems at hand and proposes solutions on how to eliminate the inconsistencies. Data sets of sunspot magnetic field strength visual measurements from Mt. Wilson, Crimea and Kyiv observatories in 2010-2012 have been processed. It is found that two measurement modes of Zeeman split, σ → σ and σ → π, yield almost the same results, if data rows are long enough (over ∼100 sunspots in central area of Sun, r < 0.7 R). It is generally held that the most reliable measurement results are obtained for magnetic fields that exceed 2400 G. However, the empirical comparison of the internal data consistency of the samples produced by different observers shows that for reliable results this limit can be lowered down to 1100 G. To increase the precision of measurements, empirical calibration of the line-shifter is required by using closely positioned telluric lines. Such calibrations have been performed at Kyiv and Crimea, but as far as we know, it has not been carried out at Mt. Wilson observatory after its diffraction grate was replaced in 1994. Taking into consideration the highest quality and coverage of Mt. Wilson sunspot observational data, the authors are convinced that reliable calibration of its instrument by narrow telluric lines is definitely required.

  18. Dynamic Pressure Probes Developed for Supersonic Flow-Field Measurements

    NASA Technical Reports Server (NTRS)

    Porro, A. Robert

    2001-01-01

    A series of dynamic flow-field pressure probes were developed for use in large-scale supersonic wind tunnels at the NASA Glenn Research Center. These flow-field probes include pitot and static pressure probes that can capture fast-acting flow-field pressure transients occurring on a millisecond timescale. The pitot and static probes can be used to determine local Mach number time histories during a transient event. The flow-field pressure probe contains four major components: 1) Static pressure aerodynamic tip; 2) Pressure-sensing cartridge assembly; 3) Pitot pressure aerodynamic tip; 4) Mounting stem. This modular design allows for a variety of probe tips to be used for a specific application. Here, the focus is on flow-field pressure measurements in supersonic flows, so we developed a cone-cylinder static pressure tip and a pitot pressure tip. Alternatively, probe tips optimized for subsonic and transonic flows could be used with this design. The pressure-sensing cartridge assembly allows the simultaneous measurement of steady-state and transient pressure which allows continuous calibration of the dynamic pressure transducer.

  19. Mobility Measurement Based on Visualized Electric Field Migration in Organic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Manaka, Takaaki; Liu, Fei; Weis, Martin; Iwamoto, Mitsumasa

    2009-06-01

    Based on the transient electric field migration directly probed by the time-resolved microscopic optical second-harmonic generation (TRM-SHG) technique, we developed a “dynamic” approach to evaluate the carrier mobility in organic field-effect transistor (OFET). The accuracy of this potential- and current-independent approach was well confirmed by computational simulations and a comparison with the conventional mobility measured by OFET transfer characteristics.

  20. Measuring exposed magnetic fields of welders in working time.

    PubMed

    Yamaguchi-Sekino, Sachiko; Ojima, Jun; Sekino, Masaki; Hojo, Minoru; Saito, Hiroyuki; Okuno, Tsutomu

    2011-01-01

    The assessment of the occupational electromagnetic field exposure of welders is of great importance, especially in shielded-arc welding, which uses relatively high electric currents of up to several hundred amperes. In the present study, we measured the magnetic field exposure level of welders in the course of working. A 3-axis Hall magnetometer was attached to a subject's wrist in order to place the sensor probe at the closest position to the magnetic source (a cable from the current source). Data was acquired every 5 s from the beginning of the work time. The maximum exposed field was 0.35-3.35 mT (Mean ± SD: 1.55 ± 0.93 mT, N=17) and the average value per day was 0.04-0.12 mT (Mean ± SD: 0.07 ± 0.02 mT, N=17). We also conducted a finite element method-based analysis of human hand tissue for the electromagnetic field dosimetry. In addition, the magnetic field associated with grinders, an air hammer, and a drill using electromagnetic anchorage were measured; however, the magnetic fields were much lower than those generated in the welding process. These results agreed well with the results of the electromagnetic field dosimetry (1.49 mT at the wrist position), and the calculated eddy current (4.28 mA/m(2)) was much lower than the well-known guideline thresholds for electrical nerve or muscular stimulation. PMID:21670555

  1. Field Survey Measures of Olfaction: The Olfactory Function Field Exam (OFFE)

    PubMed Central

    Kern, David W.; Wroblewski, Kristen E.; Schumm, L. Philip; Pinto, Jayant M.; McClintock, Martha K.

    2016-01-01

    Population-based field research on human olfaction has been limited by a lack of feasible assessment tools. Previous olfactory survey research has measured only odor identification, with no research being done on odor detection (i.e., a person's sensitivity to detect a particular odor). Laboratory studies suggest that deficits in both aspects of olfactory function may be related to physical health, mental health and cognition, social function, including overall quality of life, and even mortality. However, field studies are needed to validate and extend these findings in large representative samples. Here we describe the olfactory function field exam, an instrument that can be deployed in field environments by lay interviewers to evaluate both odor identification and odor detection rapidly, practically, and accurately. Use of this new survey tool in future field-based population health studies will elucidate the impact of olfactory function on a myriad of health and social conditions. PMID:27226782

  2. Scanning Hall probe measurements of field distributions of a coated conductor under applied fields

    NASA Astrophysics Data System (ADS)

    Yoo, Jaeun; Jung, Yonghwan; Lee, Jaeyoung; Lim, Sunme; Moo Lee, Sang; Jung, Ye Hyun; Youm, Dojun; Kim, Hosup; Ha, Hong Soo; Oh, Sangsoo

    2006-12-01

    We measured the field profiles near the surface of a coated conductor (CC) under various applied fields by using the scanning Hall probe method. The field, applied in the normal direction, was increased from zero to 171.5 Oe and then decreased to -58.8 Oe. We could not analyse our data completely by the direct use of Brandt's calculation but by a modification with unusual field dependences of the introduced parameters. Since Brandt's original calculation was based on homogeneous films, it was not suitable for CCs with coarse granular structures. The modified calculations with appropriate parameters are related to the coarse granular structures. Those parameters, D, Jc, and R, represent the three characteristics of the flux penetration network: the average distance of flux penetrations, the density of critical sheet currents, and the range of meandering of the flux penetration front, respectively. The external field dependences of these parameters were different from those of the classical critical state model.

  3. Utilizing nitrogen-vacancy centers to measure oscillating magnetic fields

    NASA Astrophysics Data System (ADS)

    Chaudhry, Adam Zaman

    2014-10-01

    We show how nitrogen-vacancy centers can be used to determine the amplitude, phase, and frequency of unknown weak monochromatic and multichromatic oscillating magnetic fields using only the periodic dynamical decoupling and Carr-Purcell-Meiboom-Gill sequences. The effect of decoherence on the measurement of the magnetic field parameters is explicitly analyzed, and we take into account the fact that different pulse sequences suppress decoherence to different extents. Since the sensitivity increases with increasing sensing time while it decreases due to decoherence and limited photon detection efficiency, we use the Fisher information matrix in order to optimize the number of pulses that should be used.

  4. High-precision measurements of global stellar magnetic fields

    NASA Astrophysics Data System (ADS)

    Plachinda, S. I.

    2014-06-01

    This paper presents a brief history of the development of devices and techniques for high-precision measurements of stellar magnetic fields. Two main approaches for the processing of spectral-polarimetric observations are described: the method of least-squares deconvolution (LSD), which is used to find a mean-weighted average of the normalized polarization profile using a set of spectral lines, and a method in which each individual spectral line is used to determine the magnetic field, viz., the single line method (SL). The advantages and disadvantages of the LSD and SL methods are discussed.

  5. Field Geologist: An Android App for Measuring Rock Outcroppings

    NASA Astrophysics Data System (ADS)

    Baird, J.; Chiu, M. T.; Huang, X.; de Lanerolle, T. R.; Morelli, R.; Gourley, J. R.

    2011-12-01

    Field geologist is a mobile Android app that measures, plots, and exports strike and data in the field. When the phone is placed on the steepest part of the rock, it automatically detects dip, string, latitude and longitude. It includes a drop-down menu to record the type of rock. The app's initial screen displays a compass with an interior dip/strike symbol that always points toward the dip direction. Tapping the compass stores a data point in the phone's database. The points can be displayed on a Google map and uploaded to a server, from where they can be retrieved in CSV format and imported into a spreadsheet.

  6. Substituting EMC emission measurement by field and cable scan method using measured transfer function

    NASA Astrophysics Data System (ADS)

    Rinas, D.; Jia, J.; Zeichner, A.; Frei, S.

    2013-07-01

    Today EMC emissions of automotive components are often measured in anechoic chambers by an antenna at fixed position according to CISPR 25 (ALSE-method). The antenna voltage often cannot sufficiently describe the behaviour of the measured electronic components and systems. Furthermore space requirements and costs are very high for the ALSE-method. Field- and cable-scan methods combined with near-field to far-field transformation techniques might be a good alternative. Residual reflections from the walls, the metallic floor, the measuring table, interaction of the antenna with the environment, and other factors affect the measurements. Thus, models which only regard the current distribution for near- and far field calculation cannot produce results equal to a chamber measurement. In this paper methods for computing transfer functions for the substitution of EMC antenna measurements with field- and cable scans in a specified calibration area are introduced. To consider influences of the environment, the environment is characterized in a first step and included with transfer functions in the calculation process for the equivalent ALSE-field.

  7. Particle and field measurements of the Starfish diamagnetic cavity

    NASA Astrophysics Data System (ADS)

    Dyal, Palmer

    2006-12-01

    Recently analyzed beta particle and magnetic field measurements obtained from five instrumented rocket payloads located around the 1962 Starfish nuclear burst are used to describe the diamagnetic cavity produced in the geomagnetic field. Three of the payloads were located in the cavity during its expansion and collapse, one payload was below, and the fifth was above the fully expanded cavity. This multipoint data set shows that the cavity expanded into an elongated shape 1840 km along the magnetic field lines and 680 km vertically across in 1.2 s and required an unexpectedly long time of about 16 s to collapse. The beta flux contained inside the cavity was measured to be relatively uniform throughout and remained at 3 × 1011 beta/cm2 s for at least 7 s. The plasma continued to expand upward beyond the fully expanded cavity boundary and injected a flux measuring 2.5 × 1010 beta/cm2 s at H + 34 s into the most intense region of the artificial belt. Measured 10 hours later by the Injun I spacecraft, this flux was determined to be 1 × 109 beta/cm2 s.

  8. Domain switching emission from the mixed-mode crack in ferroelectrics by birefringence measurement and phase field modeling

    NASA Astrophysics Data System (ADS)

    Li, Qun; Pan, Suxin; Liu, Qida; Wang, Jie

    2016-07-01

    The spatial and temporal evolution of domain switching near the tip of a mixed-mode crack (e.g., an inclined crack) is observed in ferroelectrics. The birefringence technique is used to measure the optical quantities to demonstrate the domain switching near the crack tip. The results show an intriguing feature that there appears electrical creep and domain switching emission from the crack tip. The actual time-dependence of domain switching emission and its anisotropic velocity is approximately measured. Moreover, the phase field modeling is developed to simulate polarization distribution and domain switching near the crack tip where the time-dependent Ginzburg–Landau equation is used to describe the change of polarization. The phase field results indicate the same features of domain switching emission from the mixed-mode crack. A good agreement between phase field simulation and birefringence measurement is concluded by setting the appropriate kinetic coefficient in the time-dependent Ginzburg–Landau equation.

  9. Electric field variations during substorms: OGO-6 measurements

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1972-01-01

    The OGO-6 electric field measurements make it clear that the general pattern of high latitude electric fields in magnetic time-invariant latitude coordinates is not highly variable and that when unusual variations, or field distributions, occur they are relatively isolated in time and spatial extent. Thus, electric field changes on a global scale cannot, in general, be evoked as a direct cause of substorms. Polar traverses along the 18(h) to 6(h) magnetic time meridian show that the sum of potential drops across the evening auroral belt and morning auroral belt approximately equals the potential drop across the polar cap. The integrated polar cap potential drop ranges from 20 to 100 keV and values in the center of this range are most common under conditions of moderate magnetic disturbance. Roughly near 18(h) magnetic local time, a latitudinally narrow strip at the transition between auroral belt and polar cap fields exhibits unusually large field fluctuations immediately following the sudden onset of a negative bay at later magnetic local times. It appears likely that this spatially isolated correlation is related to an effect rather than a cause of substorm enhancement.

  10. Measuring electromagnetic fields (EMF) around wind turbines in Canada: is there a human health concern?

    PubMed Central

    2014-01-01

    Background The past five years has seen considerable expansion of wind power generation in Ontario, Canada. Most recently worries about exposure to electromagnetic fields (EMF) from wind turbines, and associated electrical transmission, has been raised at public meetings and legal proceedings. These fears have not been based on any actual measurements of EMF exposure surrounding existing projects but appear to follow from worries from internet sources and misunderstanding of the science. Methods The study was carried out at the Kingsbridge 1 Wind Farm located near Goderich, Ontario, Canada. Magnetic field measurements were collected in the proximity of 15 Vestas 1.8 MW wind turbines, two substations, various buried and overhead collector and transmission lines, and nearby homes. Data were collected during three operational scenarios to characterize potential EMF exposure: ‘high wind’ (generating power), ‘low wind’ (drawing power from the grid, but not generating power) and ‘shut off’ (neither drawing, nor generating power). Results Background levels of EMF (0.2 to 0.3 mG) were established by measuring magnetic fields around the wind turbines under the ‘shut off’ scenario. Magnetic field levels detected at the base of the turbines under both the ‘high wind’ and ‘low wind’ conditions were low (mean = 0.9 mG; n = 11) and rapidly diminished with distance, becoming indistinguishable from background within 2 m of the base. Magnetic fields measured 1 m above buried collector lines were also within background (≤ 0.3 mG). Beneath overhead 27.5 kV and 500 kV transmission lines, magnetic field levels of up to 16.5 and 46 mG, respectively, were recorded. These levels also diminished rapidly with distance. None of these sources appeared to influence magnetic field levels at nearby homes located as close as just over 500 m from turbines, where measurements immediately outside of the homes were ≤ 0.4 mG. Conclusions The results suggest that there is

  11. Calculated and measured fields in superferric wiggler magnets

    SciTech Connect

    Blum, E.B.; Solomon, L.

    1995-02-01

    Although Klaus Halbach is widely known and appreciated as the originator of the computer program POISSON for electromagnetic field calculation, Klaus has always believed that analytical methods can give much more insight into the performance of a magnet than numerical simulation. Analytical approximations readily show how the different aspects of a magnet`s design such as pole dimensions, current, and coil configuration contribute to the performance. These methods yield accuracies of better than 10%. Analytical methods should therefore be used when conceptualizing a magnet design. Computer analysis can then be used for refinement. A simple model is presented for the peak on-axis field of an electro-magnetic wiggler with iron poles and superconducting coils. The model is applied to the radiator section of the superconducting wiggler for the BNL Harmonic Generation Free Electron Laser. The predictions of the model are compared to the measured field and the results from POISSON.

  12. Aircraft measurements and analysis of severe storms: 1975 field experiment

    NASA Technical Reports Server (NTRS)

    Sinclair, P. C.

    1976-01-01

    Three aircraft and instrumentation systems were acquired in support of the severe storm surveillance program. The data results indicate that the original concept of a highly mobile research aircraft capability for obtaining detailed measurements of wind, temperature, dew point, etc., near and within specifically designated severe storms is entirely feasible and has been demonstrated for the first time by this program. This program is unique in that it is designed to be highly mobile in order to move to and/or with the developing storm systems to obtain the necessary measurements. Previous programs have all been fixed to a particular location and therefore have had to wait for the storms to come within their network. The present research is designed around a highly mobile aircraft measurements group in order to maximize the storm cases during the field measurements program.

  13. High-frequency electric field measurement using a toroidal antenna

    SciTech Connect

    Lee, K.H.

    1997-01-01

    In this paper the author describes an innovative method of measuring high-frequency electric fields using a toroid. For typical geophysical applications the new sensor will detect electric fields for a wide range of spectrum starting from 1.0 MHz. This window, in particular the lower frequency range between 1.0 to 100 MHz, has not been used for existing electromagnetic or radar systems to detect small objects in the upper few meters of the ground. Ground penetrating radar (GPR) can be used successfully in this depth range if the ground is resistive but most soils are, in fact, conductive (0.01 to 1.0 S/m) rendering GPR inefficient. Other factors controlling the resolution of GPR system for small objects is the spatial averaging inherent in the electric dipole antenna and the scattering caused by soil inhomogeneities of dimensions comparable to the wavelength (and antenna size). For maximum resolution it is desirable to use the highest frequencies but the scattering is large and target identification is poor. Time-varying magnetic fields induce an emf (voltage) in a toroid. The electric field at the center of the toroid is shown to be linearly related to this induced voltage. By measuring the voltage across a toroid one can easily and accurately determine the electric field. The new sensor will greatly simplify the cumbersome procedure involved with GPR measurements with its center frequency less than 100 MHz. The overall size of the toroidal sensor can be as small as a few inches. It is this size advantage that will not only allow easy fabrication and deployment of multi-component devices either on the surface or in a borehole, but it will render greatly improved resolution over conventional systems.

  14. The laser measurement technology of combustion flow field

    NASA Astrophysics Data System (ADS)

    Wang, Mingdong; Wang, Guangyu; Qu, Dongsheng

    2014-07-01

    The parameters of combustion flow field such as temperature, velocity, pressure and mole-fraction are of significant value in engineering application. The laser spectroscopy technology which has the non-contact and non- interference properties has become the most important method and it has more advantages than conventionally contacting measurement. Planar laser induced fluorescence (PLIF/LIF) is provided with high sensibility and resolution. Filtered Rayleigh scattering (FRS) is a good measurement method for complex flow field .Tunable diode laser absorption spectroscopy (TDLAS) is prosperity on development and application. This article introduced the theoretical foundation, technical principle, system structure, merits and shortages. It is helpful for researchers to know about the latest development tendency and do the related research.

  15. Development of optical modulators for measurements of solar magnetic fields

    NASA Astrophysics Data System (ADS)

    West, E. A.; Smith, J. E.

    1987-10-01

    The measurement of polarized light allows solar astronomers to infer the magnetic field on the Sun. The accuracy of these measurements is dependent on the stable retardation characteristics of the polarization modulators used to minimize the atmospheric effects seen in ground-based observations. This report describes the work by the Space Science Laboratory at Marshall Space Flight Center to improve two types of polarization modulators. As a result, the timing characteristics for both electrooptic crystals (KD*Ps) and liquid crystal devices (LCDs) have been studied and will be used to enhance the capabilities of the MSFC Vector Magnetograph.

  16. Ways to measure body temperature in the field.

    PubMed

    Langer, Franz; Fietz, Joanna

    2014-05-01

    Body temperature (Tb) represents one of the key parameters in ecophysiological studies with focus on energy saving strategies. In this study we therefore comparatively evaluated the usefulness of two types of temperature-sensitive passive transponders (LifeChips and IPTT-300) and one data logger (iButton, DS1922L) mounted onto a collar to measure Tb in the field. First we tested the accuracy of all three devices in a water bath with water temperature ranging from 0 to 40°C. Second, we evaluated the usefulness of the LifeChips and the modified iButtons for measuring Tb of small heterothermic mammals under field conditions. For this work we subcutaneously implanted 14 male edible dormice (Glis glis) with transponders, and equipped another 14 males with data loggers to simultaneously record Tb and oxygen consumption with a portable oxygen analyzer (Oxbox). In one individual we recorded Tb with both devices and analyzed recorded Tb patterns. LifeChips are able to measure temperature within the smallest range from 25 to 40°C with an accuracy of 0.07±0.12°C. IPTT-300 transponders measured temperature between 10 and 40°C, but accuracy decreased considerably at values below 30°C, with maximal deviations of nearly 7°C. An individual calibration of each transponder is therefore needed, before using it at low Tbs. The accuracy of the data logger was comparatively good (0.12±0.25°C) and stable over the whole temperature range tested (0-40°C). In all three devices, the repeatability of measurements was high. LifeChip transponders as well as modified iButtons measured Tb reliably under field conditions. Simultaneous Tb-recordings in one edible dormouse with an implanted LifeChip and a collar-mounted iButton revealed that values of both measurements were closely correlated. Taken together, we conclude that implanted temperature-sensitive transponders represent an appropriate and largely non-invasive method to measure Tb also under field conditions. PMID:24802148

  17. Verifying a Simplified Fuel Oil Flow Field Measurement Protocol

    SciTech Connect

    Henderson, H.; Dentz, J.; Doty, C.

    2013-07-01

    The Better Buildings program is a U.S. Department of Energy program funding energy efficiency retrofits in buildings nationwide. The program is in need of an inexpensive method for measuring fuel oil consumption that can be used in evaluating the impact that retrofits have in existing properties with oil heat. This project developed and verified a fuel oil flow field measurement protocol that is cost effective and can be performed with little training for use by the Better Buildings program as well as other programs and researchers.

  18. Development of optical modulators for measurements of solar magnetic fields

    NASA Technical Reports Server (NTRS)

    West, E. A.; Smith, J. E.

    1987-01-01

    The measurement of polarized light allows solar astronomers to infer the magnetic field on the Sun. The accuracy of these measurements is dependent on the stable retardation characteristics of the polarization modulators used to minimize the atmospheric effects seen in ground-based observations. This report describes the work by the Space Science Laboratory at Marshall Space Flight Center to improve two types of polarization modulators. As a result, the timing characteristics for both electrooptic crystals (KD*Ps) and liquid crystal devices (LCDs) have been studied and will be used to enhance the capabilities of the MSFC Vector Magnetograph.

  19. Verifying a Simplified Fuel Oil Field Measurement Protocol

    SciTech Connect

    Henderson, Hugh; Dentz, Jordan; Doty, Chris

    2013-07-01

    The Better Buildings program is a U.S. Department of Energy program funding energy efficiency retrofits in buildings nationwide. The program is in need of an inexpensive method for measuring fuel oil consumption that can be used in evaluating the impact that retrofits have in existing properties with oil heat. This project developed and verified a fuel oil flow field measurement protocol that is cost effective and can be performed with little training for use by the Better Buildings program as well as other programs and researchers.

  20. Work function measurements using a field emission retarding potential technique.

    PubMed

    Hamanaka, M H M O; Dall'Agnol, F F; Pimentel, V L; Mammana, V P; Tatsch, P J; den Engelsen, D

    2016-03-01

    Herein we describe the measurement of the work function of a metal with advanced equipment based on the field emission retarding potential (FERP) method using a carbon nanotube (CNT) as cathode. The accuracy of the FERP method using a CNT emitter is described and a comparison between measurements of the work functions of aluminum, barium, calcium, gold, and platinum with published data will be presented. Our FERP equipment could be optimized with the aid of particle tracing simulations. These simulations led us to insert a magnetic collimator to improve the collection efficiency at the anode. PMID:27036828

  1. Critical field measurements in superconductors using ac inductive techniques

    NASA Astrophysics Data System (ADS)

    Campbell, S. A.; Ketterson, J. B.; Crabtree, G. W.

    1983-09-01

    The ac in-phase and out-of-phase response of type II superconductors is discussed in terms of dc magnetization curves. Hysteresis in the dc magnetization is shown to lead to a dependence of the ac response on the rate at which an external field is swept. This effect allows both Hc1 and Hc2 to be measured by ac techniques. A relatively simple mutual inductance bridge for making such measurements is described in the text, and factors affecting bridge sensitivity are discussed in the Appendix. Data for the magnetic superconductor ErRh4B4 obtained using this bridge are reported.

  2. Work function measurements using a field emission retarding potential technique

    NASA Astrophysics Data System (ADS)

    Hamanaka, M. H. M. O.; Dall'Agnol, F. F.; Pimentel, V. L.; Mammana, V. P.; Tatsch, P. J.; den Engelsen, D.

    2016-03-01

    Herein we describe the measurement of the work function of a metal with advanced equipment based on the field emission retarding potential (FERP) method using a carbon nanotube (CNT) as cathode. The accuracy of the FERP method using a CNT emitter is described and a comparison between measurements of the work functions of aluminum, barium, calcium, gold, and platinum with published data will be presented. Our FERP equipment could be optimized with the aid of particle tracing simulations. These simulations led us to insert a magnetic collimator to improve the collection efficiency at the anode.

  3. Ocean wind field measurement performance of the ERS-1 scatterometer

    NASA Technical Reports Server (NTRS)

    Hans, P.; Schuessler, H.

    1984-01-01

    The Active Microwave Instrumentation (AMI), which will be implemented on the ERS-1, is a 5.3 GHz multipurpose radar for land surface imaging, ocean wave spectrum measurement and wind observations over oceans. The imaging and wave measurements apply Synthetic Aperture Radar (SAR) techniques, while wind field detection is performed by the Scatterometer as part of the AMI. The Scatterometer system design was developed and optimized with the aid of a performance simulator. This paper, aimed at giving an overview, is presented about the: (1) ERS-1 Scatterometer system design; (2) Error budget; and the (3) Overall calibration concept.

  4. Airborne water vapor DIAL research: System development and field measurements

    NASA Technical Reports Server (NTRS)

    Higdon, Noah S.; Browell, Edward V.; Ponsardin, Patrick; Chyba, Thomas H.; Grossmann, Benoist E.; Butler, Carolyn F.; Fenn, Marta A.; Mayor, Shane D.; Ismail, Syed; Grant, William B.

    1992-01-01

    This paper describes the airborne differential absorption lidar (DIAL) system developed at the NASA Langley Research Center for remote measurement of water vapor (H2O) and aerosols in the lower atmosphere. The airborne H2O DIAL system was flight tested aboard the NASA Wallops Flight Facility (WFF) Electra aircraft in three separate field deployments between 1989 and 1991. Atmospheric measurements were made under a variety of atmospheric conditions during the flight tests, and several modifications were implemented during this development period to improve system operation. A brief description of the system and major modifications will be presented, and the most significant atmospheric observations will be described.

  5. Coronal Magnetic Field Measurement Using CME-Driven Shock Observations

    NASA Technical Reports Server (NTRS)

    Gopalswarmy, Nat; Nitta, N.; Yashiro, S.; Makela, P.; Xie, H.; Akiyama, S.

    2012-01-01

    Collisionless shocks form ahead of coronal mass ejections (CMEs) when the CME speed exceeds the Alfven speed of the ambient plasma in the corona and interplanetary medium. The shock stands at a distance from the CME flux rope that depends on the shock Mach number, the geometry of the driver, and the adiabatic index. While the shock ahead of the CME has been observed for a long time in the in situ data, it has been identified recently near the Sun in the coronagraphic and EUV images. Unlike in situ observations, the imaging observations are two dimensional, so one can better discern the CME-shock relationship near the Sun. Gopalswamy and Yashiro demonstrated that the coronal magnetic field can be derived from the shock standoff distance measured in coronagraphic images. The method involves measuring the standoff distance, the radius of curvature of the flux rope, and assuming the value of the adiabatic index and deriving the Alfvenic Mach number. The next step is to derive the Alfvenic Mach number from the measured shock speed and an estimate of the local solar wind speed. The final step involves deriving the magnetic field from the Alfven speed by measuring the local plasma density either from coronagraphic (polarized brightness) images or from the band-splitting of type II radio bursts. In this paper, we derive the combined magnetic field profile from near the Sun to the edge of the LASCO field of view (1.5 to 30 solar radii) and compare it with the current model profiles.

  6. Energetic particles and magnetic field measurements at Comet Halley

    NASA Astrophysics Data System (ADS)

    Osullivan, D.; Thompson, A.; McKenna-Lawlor, S.; Kirsch, E.; Wenzel, K.-P.; Neubauer, F. M.

    1986-12-01

    Studies of energetic charged particles in the environment of comet Halley, based on data from the EPA instrument on the Giotto spacecraft, are presented. Investigation of the lowest energy channels (p,e; 26 to 46 keV) of Telescopes 1 and 3 are reported. Investigation of the particle data in relation to magnetic field measurements made during 13 and 14 March 1986 are discussed. Overall flux patterns are similar to those of higher energy channels.

  7. Light Emitting Diodes and Astronomical Environments: Results from in situ Field Measurements

    NASA Astrophysics Data System (ADS)

    Craine, Brian L.; Craine, Eric R.

    2015-05-01

    Light emitting diode (LED) light fixtures are rapidly becoming industry standards for outdoor lighting. They are promoted on the strength of long lifetimes (hence economic efficiencies), low power requirements, directability, active brightness controls, and energy efficiency. They also tend to produce spectral shifts that are undesirable in astronomical settings, but which can be moderated by filters. LED lighting for continuous roadway and parking lot lighting is particularly popular, and many communities are in the process of retrofitting Low Pressure Sodium (LPS) and other lights by tens of thousands of new LED fixtures at a time. What is the impact of this process on astronomical observatories and on dark skies upon which amateur astronomers rely? We bypass modeling and predictions to make actual measurements of these lights in the field. We report on original ground, airborne, and satellite observations of LED lights and discuss their light budgets, zenith angle functions, and impacts on observatory environs.

  8. Standard target sets for field sensor performance measurements

    NASA Astrophysics Data System (ADS)

    O'Connor, John D.; O'Shea, Patrick; Palmer, John E.; Deaver, Dawne M.

    2006-05-01

    The US Army Night Vision and Electronic Sensors Directorate (NVESD) Modeling and Simulation Division develops sensors models (FLIR 92, NV Therm, NV Therm IP) that predict the comparative performance of electro-optical sensors. The NVESD modeling branch developed a 12-vehicle, 12-aspect target signature set in 1998 with a known cycle criteria. It will be referred to as the 12-target set. This 12-target set has and will continue to be the modeling "gold standard" for laboratory human perception experiments supporting sensor performance modeling, and has been employed in dozens of published experiments. The 12-target set is, however, too costly for most acquisition field tests and evaluations. The authors developed an 8-vehicle 3-aspect target set, referred to as the 8- target set, and measured its discrimination task difficulty, (N50 and V50). Target identification (ID) range performance predictions for several sensors were made based on those V50/N50 values. A field collection of the 8-target set using those sensors provided imagery for a human perception study. The human perception study found excellent agreement between predicted and measured range performance. The goal of this development is to create a "silver standard" target set that is as dependable in measuring sensor performance as the "gold standard", and is affordable for Milestone A and other field trials.

  9. Measurements of electric fields in the solar wind: Interpretation difficulties

    NASA Technical Reports Server (NTRS)

    Chertkov, A. D.

    1995-01-01

    The traditionally measured electric fields in the solar wind plasma (about 1-10 mV/m) are not the natural, primordial ones but are the result of plasma-vehicle interaction. The theory of this interaction is not complete now and current interpretation of the measurements can fail. The state of fully ionized plasma depends on the entropy of the creating source and on the process in which plasma is involved. The increasing twofold of a moving volume in the solar wind (with energy transfer across its surface which is comparable with its whole internal energy) is a more rapid process than the relaxation for the pressure. The presumptive source of the solar wind creation - the induction electric field of the solar origin - has very low entropy. The state of plasma must be very far from the state of thermodynamic equilibrium. The internal energy of plasma can be contained mainly in plasma waves, resonant plasma oscillations, and electric currents. The primordial microscopic oscillating electric fields could be about 1 V/m. It can be checked by special measurements, not ruining the natural plasma state. The tool should be a dielectrical microelectroscope outside the distortion zone of the spacecraft, having been observed from the latter.

  10. Gravitational spectra from direct measurements. [of surface field

    NASA Technical Reports Server (NTRS)

    Wagner, C. A.; Colombo, O. L.

    1979-01-01

    A simple rapid method is described for determining the spectrum of a surface field (in spherical harmonics) from harmonic analysis of direct (in situ) measurements along great circle arcs. The method is shown to give excellent overall trends (smoothed spectra) to very high degree from even a few short arcs of satellite data. Three examples are taken with perfect measurements of satellite tracking over a planet made up of hundreds of point masses using (1) altimetric heights from a low-orbiting spacecraft, (2) velocity (range rate) residuals between a low and a high satellite in circular orbits, and (3) range rate data between a station at infinity and a satellite in a highly eccentric orbit. In particular, the smoothed spectrum of the earth's gravitational field is determined to about degree 400(50-km half wavelength) from 1 x 1 deg gravimetry and the equivalent of 11 revolutions of GEOS 3 and Skylab altimetry. This measurement shows that there is about 46 cm of geoid height (rms worldwide) remaining in the field beyond degree 180.

  11. Particles and fields measurements at Neptune with Voyager 2

    NASA Technical Reports Server (NTRS)

    Krimigis, S. M.

    1992-01-01

    The first results of measurements performed on the Voyager 2 spacecraft with the Neptune system on August 24-28, 1989 are summarized. These include measurements of the magnetic field, plasma, energetic and high energy particles, plasma waves and radio emissions, and additional information relating to UV emissions. The planetary magnetic field outside about 4 R(N) may be described by an offset, tilted, dipole of moment 0.133 Gauss-R(N) exp 3; inside that distance the field is dominated by higher order terms. Plasma densities are found to be generally low (about 5 exp -3/cu cm), except at magnetic equatorial crossings when densities are up to about 1/cu cm. A variety of plasma wave emissions were seen, including chorus, hiss, electroncyclotron waves, and upper hybrid resonance in the inner magnetosphere. The measured flux of soft electrons and ions over the polar region of about 2 x 10 exp -3 erg/sq cm sec results in an estimated power input of about 3 x 10 exp 7 W, which is substantially less than that at other planets.

  12. Inverse method predicting spinning modes radiated by a ducted fan from free-field measurements.

    PubMed

    Lewy, Serge

    2005-02-01

    In the study the inverse problem of deducing the modal structure of the acoustic field generated by a ducted turbofan is addressed using conventional farfield directivity measurements. The final objective is to make input data available for predicting noise radiation in other configurations that would not have been tested. The present paper is devoted to the analytical part of that study. The proposed method is based on the equations governing ducted sound propagation and free-field radiation. It leads to fast computations checked on Rolls-Royce tests made in the framework of previous European projects. Results seem to be reliable although the system of equations to be solved is generally underdetermined (more propagating modes than acoustic measurements). A limited number of modes are thus selected according to any a priori knowledge of the sources. A first guess of the source amplitudes is obtained by adjusting the calculated maximum of radiation of each mode to the measured sound pressure level at the same angle. A least squares fitting gives the final solution. A simple correction can be made to take account of the mean flow velocity inside the nacelle which shifts the directivity patterns. It consists of modifying the actual frequency to keep the cut-off ratios unchanged. PMID:15759694

  13. Inverse method predicting spinning modes radiated by a ducted fan from free-field measurements

    NASA Astrophysics Data System (ADS)

    Lewy, Serge

    2005-02-01

    In the study the inverse problem of deducing the modal structure of the acoustic field generated by a ducted turbofan is addressed using conventional farfield directivity measurements. The final objective is to make input data available for predicting noise radiation in other configurations that would not have been tested. The present paper is devoted to the analytical part of that study. The proposed method is based on the equations governing ducted sound propagation and free-field radiation. It leads to fast computations checked on Rolls-Royce tests made in the framework of previous European projects. Results seem to be reliable although the system of equations to be solved is generally underdetermined (more propagating modes than acoustic measurements). A limited number of modes are thus selected according to any a priori knowledge of the sources. A first guess of the source amplitudes is obtained by adjusting the calculated maximum of radiation of each mode to the measured sound pressure level at the same angle. A least squares fitting gives the final solution. A simple correction can be made to take account of the mean flow velocity inside the nacelle which shifts the directivity patterns. It consists of modifying the actual frequency to keep the cut-off ratios unchanged. .

  14. LIDAR Wind Speed Measurements of Evolving Wind Fields

    SciTech Connect

    Simley, E.; Pao, L. Y.; Kelley, N.; Jonkman, B.; Frehlich, R.

    2012-01-01

    Light Detection and Ranging (LIDAR) systems are able to measure the speed of incoming wind before it interacts with a wind turbine rotor. These preview wind measurements can be used in feedforward control systems that are designed to reduce turbine loads. However, the degree to which such preview-based control techniques can reduce loads by reacting to turbulence depends on how accurately the incoming wind field can be measured. Past studies have assumed the validity of physicist G.I. Taylor's 1938 frozen turbulence hypothesis, which implies that turbulence remains unchanged as it advects downwind at the mean wind speed. With Taylor's hypothesis applied, the only source of wind speed measurement error is distortion caused by the LIDAR. This study introduces wind evolution, characterized by the longitudinal coherence of the wind, to LIDAR measurement simulations using the National Renewable Energy Laboratory's (NREL's) 5-megawatt turbine model to create a more realistic measurement model. A simple model of wind evolution was applied to a frozen wind field that was used in previous studies to investigate the effects of varying the intensity of wind evolution. LIDAR measurements were also evaluated using a large eddy simulation (LES) of a stable boundary layer that was provided by the National Center for Atmospheric Research. The LIDAR measurement scenario investigated consists of a hub-mounted LIDAR that scans a circle of points upwind of the turbine in order to estimate the wind speed component in the mean wind direction. Different combinations of the preview distance that is located upwind of the rotor and the radius of the scan circle were analyzed. It was found that the dominant source of measurement error for short preview distances is the detection of transverse and vertical wind speeds from the line-of-sight LIDAR measurement. It was discovered in previous studies that, in the absence of wind evolution, the dominant source of error for large preview distances

  15. A compact DOAS instrument optimised for ammonia field-measurements

    NASA Astrophysics Data System (ADS)

    Neftel, Albrecht; Sintermann, Joerg; Dietrich, Klaus; Häni, Christoph; Jocher, Markus

    2016-04-01

    Accurate, high time-resolution measurements of NH3 in ambient air are still a challenge due to the stickiness of this molecule and its interactions with inlet or instrument surfaces. Differential optical absorption spectroscopy (DOAS) with open-path arrangement offers a contact-free in-situ approach to determine ambient NH3. We present a DOAS instrument, optimised for open-path field-measurements of ambient ammonia (NH3) alongside nitrogen oxide (NO) and sulphur dioxide (SO2). This device, operating in the UV range over paths of up to 100 m, is a further development of the miniDOAS presented by Volten et al. (2012). We use a temperature-controlled spectrometer, a deuterium light source and a modified optical arrangement. The system was set up in a robust, field-deployable, temperature-regulated housing. For the evaluation of light spectra a new high-pass filter routine based upon robust baseline extraction with local regression was used. In order to fit differential absorption cross-sections to the measurements, multiple linear regression is performed including terms of an autoregressive-moving-average model. In this presentation we discuss the influence of filter and fit procedure on the precision and accuracy of the system with examples of field measurements with artificial NH3 sources. Volten, H., Bergwerff, J. B., Haaima, M., Lolkema, D. E., Berkhout, A. J. C., van der Hoff, G. R., Potma, C. J. M., Wichink Kruit, R. J., van Pul, W. A. J. and Swart, D. P. J.: Two instruments based on differential optical absorption spectroscopy (DOAS) to measure accurate ammonia concentrations in the atmosphere, Atmospheric Meas. Tech., 5(2), 413-427, doi:10.5194/amt-5-413-2012, 2012.

  16. Optical surface pressure measurements: Accuracy and application field evaluation

    NASA Astrophysics Data System (ADS)

    Bukov, A.; Mosharov, V.; Orlov, A.; Pesetsky, V.; Radchenko, V.; Phonov, S.; Matyash, S.; Kuzmin, M.; Sadovskii, N.

    1994-07-01

    Optical pressure measurement (OPM) is a new pressure measurement method rapidly developed in several aerodynamic research centers: TsAGI (Russia), Boeing, NASA, McDonnell Douglas (all USA), and DLR (Germany). Present level of OPM-method provides its practice as standard experimental method of aerodynamic investigations in definite application fields. Applications of OPM-method are determined mainly by its accuracy. The accuracy of OPM-method is determined by the errors of three following groups: (1) errors of the luminescent pressure sensor (LPS) itself, such as uncompensated temperature influence, photo degradation, temperature and pressure hysteresis, variation of the LPS parameters from point to point on the model surface, etc.; (2) errors of the measurement system, such as noise of the photodetector, nonlinearity and nonuniformity of the photodetector, time and temperature offsets, etc.; and (3) methodological errors, owing to displacement and deformation of the model in an airflow, a contamination of the model surface, scattering of the excitation and luminescent light from the model surface and test section walls, etc. OPM-method allows getting total error of measured pressure not less than 1 percent. This accuracy is enough to visualize the pressure field and allows determining total and distributed aerodynamic loads and solving some problems of local aerodynamic investigations at transonic and supersonic velocities. OPM is less effective at low subsonic velocities (M less than 0.4), and for precise measurements, for example, an airfoil optimization. Current limitations of the OPM-method are discussed on an example of the surface pressure measurements and calculations of the integral loads on the wings of canard-aircraft model. The pressure measurement system and data reduction methods used on these tests are also described.

  17. Modeling and Measurement of Ocean Generated Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Liang, R.; Avera, W. E.; Nelson, J.; Brozena, J. M.

    2011-12-01

    Motion of conductive seawater through the earth's magnetic field will produce magnetic fields. Magnetic fields from motions such as ocean waves and swells are detectable near the ocean's surface but decay rapidly with distance. Non-linear internal waves (NLIWs) generated by mechanisms such as tides over bathymetric features have been predicted to produce magnetic anomalies of .1-1 nT at altitudes of ~ 100 m above the surface (Chave, 1986) due to the large volumes of coherently moving water. An experiment was performed in 2009 by the Defense Research and Development Canada (DRDC) and the US Naval Research Laboratory (NRL) to see if magnetic signatures predicted from oceanographic measurements could be detected by airborne and ocean bottom mounted magnetometers. The test was conducted near the shelf-break off the coast of New Jersey where NLIWs have been observed. Oceanographic measurements were collected by a set of bottom-mounted ADCPs, towed C-T sensors mounted on a "SCANFISH" tow-body, and a hull-mounted ADCP. Magnetic measurements consisted of total-field magnetometers co-located with the bottom mounted ADCPs, three magnetic base-stations (total field and vector) in New Jersey for geomagnetic noise cancellation, and magnetometers aboard two aircraft ( a Canadian National Research Council Convair 580 and the NRL P-3) flown simultaneously with a 20-30 second separation ( corresponding to 2-3 km) along a repeat track over the bottom-mounted sensors. The multiple aircraft and repeat tracks were intended to remove the spatially stationary geologic component. The time-varying geomagnetic signal was extrapolated from the magnetic base-stations to the aircraft measurements. Both aircraft had high quality magnetometers and magnetic-field compensation systems based on co-located vector magnetometers and kinematic GPS. The Convair had two magnetometer and compensation systems mounted in wing-pods with a base-line of ~ 32 m that allowed the calculation of a cross

  18. Tunneling Time and Weak Measurement in Strong Field Ionization

    NASA Astrophysics Data System (ADS)

    Zimmermann, Tomáš; Mishra, Siddhartha; Doran, Brent R.; Gordon, Daniel F.; Landsman, Alexandra S.

    2016-06-01

    Tunneling delays represent a hotly debated topic, with many conflicting definitions and little consensus on when and if such definitions accurately describe the physical observables. Here, we relate these different definitions to distinct experimental observables in strong field ionization, finding that two definitions, Larmor time and Bohmian time, are compatible with the attoclock observable and the resonance lifetime of a bound state, respectively. Both of these definitions are closely connected to the theory of weak measurement, with Larmor time being the weak measurement value of tunneling time and Bohmian trajectory corresponding to the average particle trajectory, which has been recently reconstructed using weak measurement in a two-slit experiment [S. Kocsis, B. Braverman, S. Ravets, M. J. Stevens, R. P. Mirin, L. K. Shalm, and A. M. Steinberg, Science 332, 1170 (2011)]. We demonstrate a big discrepancy in strong field ionization between the Bohmian and weak measurement values of tunneling time, and we suggest this arises because the tunneling time is calculated for a small probability postselected ensemble of electrons. Our results have important implications for the interpretation of experiments in attosecond science, suggesting that tunneling is unlikely to be an instantaneous process.

  19. Tunneling Time and Weak Measurement in Strong Field Ionization.

    PubMed

    Zimmermann, Tomáš; Mishra, Siddhartha; Doran, Brent R; Gordon, Daniel F; Landsman, Alexandra S

    2016-06-10

    Tunneling delays represent a hotly debated topic, with many conflicting definitions and little consensus on when and if such definitions accurately describe the physical observables. Here, we relate these different definitions to distinct experimental observables in strong field ionization, finding that two definitions, Larmor time and Bohmian time, are compatible with the attoclock observable and the resonance lifetime of a bound state, respectively. Both of these definitions are closely connected to the theory of weak measurement, with Larmor time being the weak measurement value of tunneling time and Bohmian trajectory corresponding to the average particle trajectory, which has been recently reconstructed using weak measurement in a two-slit experiment [S. Kocsis, B. Braverman, S. Ravets, M. J. Stevens, R. P. Mirin, L. K. Shalm, and A. M. Steinberg, Science 332, 1170 (2011)]. We demonstrate a big discrepancy in strong field ionization between the Bohmian and weak measurement values of tunneling time, and we suggest this arises because the tunneling time is calculated for a small probability postselected ensemble of electrons. Our results have important implications for the interpretation of experiments in attosecond science, suggesting that tunneling is unlikely to be an instantaneous process. PMID:27341232

  20. Altimeter measurements for the determination of the Earth's gravity field

    NASA Technical Reports Server (NTRS)

    Tapley, B. D.; Schutz, B. E.; Shum, C. K.

    1987-01-01

    The ability of satellite-borne radar altimeter data to measure the global ocean surface with high precision and dense spatial coverage provides a unique tool for the mapping of the Earth's gravity field and its geoid. The altimeter crossover measurements, created by differencing direct altimeter measurements at the subsatellite points where the orbit ground tracks intersect, have the distinct advantage of eliminating geoid error and other nontemporal or long period oceanographic features. In the 1990's, the joint U.S./French TOPEX/POSEIDON mission and the European Space Agency's ERS-1 mission will carry radar altimeter instruments capable of global ocean mapping with high precision. This investigation aims at the development and application of dynamically consistent direct altimeter and altimeter crossover measurement models to the simultaneous mapping of the Earth's gravity field and its geoid, the ocean tides and the quasi-stationary component of the dynamic sea surface topography. Altimeter data collected by SEASAT, GEOS-3, and GEOSAT are used for the investigation.

  1. Measurement of Radiation - Light Field Congruence using a Photodiode Array

    NASA Astrophysics Data System (ADS)

    Balderson, Michael J.

    Improved treatment techniques in radiation therapy provide incentive to reduce treatment margins, thereby increasing the necessity for more accurate geometrical setup of the linear accelerator and accompanying components. In this thesis, we describe the development of a novel device that enables precise and automated measurement of radiation-light field congruence of medical linear accelerators for the purpose of improving setup accuracy, and standardizing repeated quality control activities. The device consists of a silicon photodiode array, an evaluation board, a data acquisition card, and a laptop. Using the device, we show that the radiation-light field congruence for both 6 and 15 MV beams is within 2 mm on a Varian Clinac 21 EX medical linear accelerator. Because measurements are automated, ambiguities resulting from observer variability are removed, greatly improving the reproducibility of measurements over time and across observers. We expect the device to be useful in providing consistent measurements on linear accelerators used for stereotactic radiosurgery, during the commissioning of new linear accelerators, and as an alternative to film or other commercially available devices for performing monthly or annual quality control checks.

  2. A Portable, Field-Deployable Analyzer for Isotopic Water Measurements

    NASA Astrophysics Data System (ADS)

    Berman, E. S.; Gupta, M.; Huang, Y. W.; Lacelle, D.; McKay, C. P.; Fortson, S.

    2015-12-01

    Water stable isotopes have for many years been used to study the hydrological cycle, catchment hydrology, and polar climate among other applications. Typically, discrete water samples are collected and transported to a laboratory for isotope analysis. Due to the expense and labor associated with such sampling, isotope studies have generally been limited in scope and time-resolution. Field sampling of water isotopes has been shown in recent years to provide dense data sets with the increased time resolution illuminating substantially greater short term variability than is generally observed during discrete sampling. A truly portable instrument also opens the possibility to utilize the instrument as a tool for identifying which water samples would be particularly interesting for further laboratory investigation. To make possible such field measurements of liquid water isotopes, Los Gatos Research has developed a miniaturized, field-deployable liquid water isotope analyzer. The prototype miniature liquid water isotope analyzer (mini-LWIA) uses LGR's patented Off-Axis ICOS (Integrated Cavity Output Spectroscopy) technology in a rugged, Pelican case housing for easy transport and field operations. The analyzer simultaneously measures both δ2H and δ18O from liquid water, with both manual and automatic water introduction options. The laboratory precision for δ2H is 0.6 ‰, and for δ18O is 0.3 ‰. The mini-LWIA was deployed in the high Arctic during the summer of 2015 at Inuvik in the Canadian Northwest Territories. Samples were collected from Sachs Harbor, on the southwest coast of Banks Island, including buried basal ice from the Lurentide Ice Sheet, some ice wedges, and other types of ground ice. Methodology and water analysis results from this extreme field deployment will be presented.

  3. Biomass burning fuel consumption rates: a field measurement database

    NASA Astrophysics Data System (ADS)

    van Leeuwen, T. T.; van der Werf, G. R.; Hoffmann, A. A.; Detmers, R. G.; Rücker, G.; French, N. H. F.; Archibald, S.; Carvalho, J. A., Jr.; Cook, G. D.; de Groot, W. J.; Hély, C.; Kasischke, E. S.; Kloster, S.; McCarty, J. L.; Pettinari, M. L.; Savadogo, P.; Alvarado, E. C.; Boschetti, L.; Manuri, S.; Meyer, C. P.; Siegert, F.; Trollope, L. A.; Trollope, W. S. W.

    2014-06-01

    Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. These fuel consumption (FC) rates depend on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC rates are either modeled or taken selectively from the literature. We compiled the peer-reviewed literature on FC rates for various biomes and fuel categories to better understand FC rates and variability, and to provide a~database that can be used to constrain biogeochemical models with fire modules. We compiled in total 76 studies covering 10 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter) ha-1), tropical forest (n = 19, FC = 126), temperate forest (n = 11, FC = 93), boreal forest (n = 16, FC = 39), pasture (n = 6, FC = 28), crop residue (n = 4, FC = 6.5), chaparral (n = 2, FC = 32), tropical peatland (n = 4, FC = 314), boreal peatland (n = 2, FC = 42), and tundra (n = 1, FC = 40). Within biomes the regional variability in the number of measurements was sometimes large, with e.g. only 3 measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences were found within the defined biomes: for example FC rates of temperate pine forests in the USA were 38% higher than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC rates, not only between biomes but also within biomes and fuel classes. This implies that care should be taken with using averaged values, and our comparison with FC rates from GFED3 indicates that also modeling studies have difficulty in representing the dynamics governing FC.

  4. Turbulence Measurements in the Near Field of a Wingtip Vortex

    NASA Technical Reports Server (NTRS)

    Chow, Jim; Zilliac, Greg; Bradshaw, Peter

    1997-01-01

    The roll-up of a wingtip vortex, at Reynolds number based on chord of 4.6 million was studied with an emphasis on suction side and near wake measurements. The research was conducted in a 32 in. x 48 in. low-speed wind tunnel. The half-wing model had a semi-span of 36 in. a chord of 48 in. and a rounded tip. Seven-hole pressure probe measurements of the velocity field surrounding the wingtip showed that a large axial velocity of up to 1.77 U(sub infinity) developed in the vortex core. This level of axial velocity has not been previously measured. Triple-wire probes have been used to measure all components of the Reynolds stress tensor. It was determined from correlation measurements that meandering of the vortex was small and did not appreciably contribute to the turbulence measurements. The flow was found to be turbulent in the near-field (as high as 24 percent RMS w - velocity on the edge of the core) and the turbulence decayed quickly with streamwise distance because of the nearly solid body rotation of the vortex core mean flow. A streamwise variation of the location of peak levels of turbulence, relative to the core centerline, was also found. Close to the trailing edge of the wing, the peak shear stress levels were found at the edge of the vortex core, whereas in the most downstream wake planes they occurred at a radius roughly equal to one-third of the vortex core radius. The Reynolds shear stresses were not aligned with the mean strain rate, indicating that an isotropic-eddy-viscosity based prediction method cannot accurately model the turbulence in the cortex. In cylindrical coordinates, with the origin at the vortex centerline, the radial normal stress was found to be larger than the circumferential.

  5. Field-Deployable Acoustic Digital Systems for Noise Measurement

    NASA Technical Reports Server (NTRS)

    Shams, Qamar A.; Wright, Kenneth D.; Lunsford, Charles B.; Smith, Charlie D.

    2000-01-01

    Langley Research Center (LaRC) has for years been a leader in field acoustic array measurement technique. Two field-deployable digital measurement systems have been developed to support acoustic research programs at LaRC. For several years, LaRC has used the Digital Acoustic Measurement System (DAMS) for measuring the acoustic noise levels from rotorcraft and tiltrotor aircraft. Recently, a second system called Remote Acquisition and Storage System (RASS) was developed and deployed for the first time in the field along with DAMS system for the Community Noise Flight Test using the NASA LaRC-757 aircraft during April, 2000. The test was performed at Airborne Airport in Wilmington, OH to validate predicted noise reduction benefits from alternative operational procedures. The test matrix was composed of various combinations of altitude, cutback power, and aircraft weight. The DAMS digitizes the acoustic inputs at the microphone site and can be located up to 2000 feet from the van which houses the acquisition, storage and analysis equipment. Digitized data from up to 10 microphones is recorded on a Jaz disk and is analyzed post-test by microcomputer system. The RASS digitizes and stores acoustic inputs at the microphone site that can be located up to three miles from the base station and can compose a 3 mile by 3 mile array of microphones. 16-bit digitized data from the microphones is stored on removable Jaz disk and is transferred through a high speed array to a very large high speed permanent storage device. Up to 30 microphones can be utilized in the array. System control and monitoring is accomplished via Radio Frequency (RF) link. This paper will present a detailed description of both systems, along with acoustic data analysis from both systems.

  6. Lorentz force electrical impedance tomography using magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Zengin, Reyhan; Güneri Gençer, Nevzat

    2016-08-01

    In this study, magnetic field measurement technique is investigated to image the electrical conductivity properties of biological tissues using Lorentz forces. This technique is based on electrical current induction using ultrasound together with an applied static magnetic field. The magnetic field intensity generated due to induced currents is measured using two coil configurations, namely, a rectangular loop coil and a novel xy coil pair. A time-varying voltage is picked-up and recorded while the acoustic wave propagates along its path. The forward problem of this imaging modality is defined as calculation of the pick-up voltages due to a given acoustic excitation and known body properties. Firstly, the feasibility of the proposed technique is investigated analytically. The basic field equations governing the behaviour of time-varying electromagnetic fields are presented. Secondly, the general formulation of the partial differential equations for the scalar and magnetic vector potentials are derived. To investigate the feasibility of this technique, numerical studies are conducted using a finite element method based software. To sense the pick-up voltages a novel coil configuration (xy coil pairs) is proposed. Two-dimensional numerical geometry with a 16-element linear phased array (LPA) ultrasonic transducer (1 MHz) and a conductive body (breast fat) with five tumorous tissues is modeled. The static magnetic field is assumed to be 4 Tesla. To understand the performance of the imaging system, the sensitivity matrix is analyzed. The sensitivity matrix is obtained for two different locations of LPA transducer with eleven steering angles from -{{25}\\circ} to {{25}\\circ} at intervals of {{5}\\circ} . The characteristics of the imaging system are shown with the singular value decomposition (SVD) of the sensitivity matrix. The images are reconstructed with the truncated SVD algorithm. The signal-to-noise ratio in measurements is assumed 80 dB. Simulation studies

  7. Lorentz force electrical impedance tomography using magnetic field measurements.

    PubMed

    Zengin, Reyhan; Gençer, Nevzat Güneri

    2016-08-21

    In this study, magnetic field measurement technique is investigated to image the electrical conductivity properties of biological tissues using Lorentz forces. This technique is based on electrical current induction using ultrasound together with an applied static magnetic field. The magnetic field intensity generated due to induced currents is measured using two coil configurations, namely, a rectangular loop coil and a novel xy coil pair. A time-varying voltage is picked-up and recorded while the acoustic wave propagates along its path. The forward problem of this imaging modality is defined as calculation of the pick-up voltages due to a given acoustic excitation and known body properties. Firstly, the feasibility of the proposed technique is investigated analytically. The basic field equations governing the behaviour of time-varying electromagnetic fields are presented. Secondly, the general formulation of the partial differential equations for the scalar and magnetic vector potentials are derived. To investigate the feasibility of this technique, numerical studies are conducted using a finite element method based software. To sense the pick-up voltages a novel coil configuration (xy coil pairs) is proposed. Two-dimensional numerical geometry with a 16-element linear phased array (LPA) ultrasonic transducer (1 MHz) and a conductive body (breast fat) with five tumorous tissues is modeled. The static magnetic field is assumed to be 4 Tesla. To understand the performance of the imaging system, the sensitivity matrix is analyzed. The sensitivity matrix is obtained for two different locations of LPA transducer with eleven steering angles from [Formula: see text] to [Formula: see text] at intervals of [Formula: see text]. The characteristics of the imaging system are shown with the singular value decomposition (SVD) of the sensitivity matrix. The images are reconstructed with the truncated SVD algorithm. The signal-to-noise ratio in measurements is assumed 80 d

  8. Enabling Continuous, Field-Based Isotope and Greenhouse Gas Measurements with WS-CRDS-based Analyzers

    NASA Astrophysics Data System (ADS)

    Rella, C.; van Pelt, A.

    2009-04-01

    When new instrumentation becomes widely available, it has the power to fundamentally change how measurements are made. In particular, technology developments that enable measurements to be done more simply, at lower cost, by a greater number of scientists, moving information-rich, laboratory-quality measurements from the lab out into the field -- these are the innovations that can aid in moving the science forward. Here we describe how the application of a novel cavity-enhanced spectroscopic technique called wavelength scanned cavity ring down spectroscopy (WS-CRDS) has been pivotal in developing gas an isotope analyzers capable of being deployed in the field, unattended, for long periods of time. This particular implementation of the traditional cavity ring down technique employs several additional key aspects of control and design to achieve highly sensitive, highly stable measurements. WS-CRDS owes its high sensitivity to an extremely long optical interaction pathlengh, as well as to its complete immunity to laser noise since the laser is actually off during the measurement. To stabilize the spectroscopic line itself, the temperature and pressure of the gas are tightly controlled. The analyzer's optical cavity, gas handling system and analog electronics are themselves also tightly temperature controlled. The heart of the WS-CRDS technique is, however, the wavelength monitor which further ensures the stability of the measurement by continuously measuring and tightly controlling the laser wavelength. A key design aspect of the WS-CRDS analyzer is its three-mirror, traveling-wave cavity which allows optical backreflections to be avoided and further adds to the inherent stability of the optical train. The analyzer owes its ease of use to the design requirement that it be field-deployable, in locations without personnel, with the ability to restart itself and automatically resume collecting data even after a power failure. Beyond the design aspects of the analyzer

  9. A magnetic field measurement technique using a miniature transducer

    NASA Technical Reports Server (NTRS)

    Fales, C. L., Jr.; Breckenridge, R. A.; Debnam, W. J., Jr.

    1974-01-01

    The development, fabrication, and application of a magnetometer are described. The magnetometer has a miniature transducer and is capable of automatic scanning. The magnetometer described here is capable of detecting static magnetic fields as low as 1.6 A/m and its transducer has an active area 0.64 mm by 0.76 mm. Thin and rugged, the transducer uses wire, 0.05 mm in diameter, which is plated with a magnetic film, enabling measurement of transverse magnetic fields as close as 0.08 mm from a surface. The magnetometer, which is simple to operate and has a fast response, uses an inexpensive clip-on milliammeter (commonly found in most laboratories) for driving and processing the electrical signals and readout. A specially designed transducer holding mechanism replaces the XY recorder ink pen; this mechanism provides the basis for an automatic scanning technique. The instrument has been applied to the measurements of magnetic fields arising from remanent magnetization in experimental plated-wire memory planes and regions of magnetic activity in geological rock specimens.

  10. Ultrastructural alterations in field carcinogenesis measured by enhanced backscattering spectroscopy

    PubMed Central

    Mutyal, Nikhil N.; Yi, Ji; Stypula-Cyrus, Yolanda; Rogers, Jeremy D.; Goldberg, Michael J.; Bianchi, Laura K.; Bajaj, Shailesh; Roy, Hemant K.; Backman, Vadim

    2013-01-01

    Abstract. Optical characterization of biological tissue in field carcinogenesis offers a method with which to study the mechanisms behind early cancer development and the potential to perform clinical diagnosis. Previously, low-coherence enhanced backscattering spectroscopy (LEBS) has demonstrated the ability to discriminate between normal and diseased organs based on measurements of histologically normal-appearing tissue in the field of colorectal (CRC) and pancreatic (PC) cancers. Here, we implement the more comprehensive enhanced backscattering (EBS) spectroscopy to better understand the structural and optical changes which lead to the previous findings. EBS provides high-resolution measurement of the spatial reflectance profile P(rs) between 30 microns and 2.7 mm, where information about nanoscale mass density fluctuations in the mucosa can be quantified. A demonstration of the length-scales at which P(rs) is optimally altered in CRC and PC field carcinogenesis is given and subsequently these changes are related to the tissue’s structural composition. Three main conclusions are made. First, the most significant changes in P(rs) occur at short length-scales corresponding to the superficial mucosal layer. Second, these changes are predominantly attributable to a reduction in the presence of subdiffractional structures. Third, similar trends are seen for both cancer types, suggesting a common progression of structural alterations in each. PMID:24008865

  11. An Explanation of the Varied Measurements of Gas Field Methane Leakage

    NASA Astrophysics Data System (ADS)

    Evans, W. F.; McHugh, M. J.

    2014-12-01

    In situ engineering measurements of natural gas well sites indicate leakage rates with a mean rate of 1.5% of the gas production rate from individual wells. These have been made at several gas basins using in situ measurements. These in situ engineering measurements are reported as the fugitive emission rates to the UNCCC by the EPA. On the other hand, atmospheric measurements at altitudes above the surface by several atmospheric groups indicate that gas fields are leaking at an average rate of over 9 %. Papers have been published in several highly reputable journals by government and university scientists. Both groups have been criticizing the methodologies of the opposite group. We propose that a more likely explanation is that both groups are correct. Although this appears as a direct conflict with one group on each side, a careful analysis shows that the two groups are measuring different air parcels. This is the only explanation which will explain the apparent conflicting situation. This can be understood if the basins in which the wells are sited are actually leaking from the bed rock formations in which the wells are drilled. If the geology of the natural gas basins is examined in detail, then the situation becomes understandable. Many basins contain gas in fault traps. These faults often leak, particularly if there is a small earthquake. The leaks can follow tilted layers, resulting in vertical transport of gas along the slanted layer cracks. This leakage may emerge into the atmosphere at large distances from the actual gas well under measurement. Fracking can obviously increase the leakage from a valley gas field. The methane leaks could alter the budgets of greenhouse gases reported by various gas producing countries by significant amounts. The potential increases and altered budgets for various countries as reported to the UNCCC are estimated and reported in this presentation. The fraction of these unreported leaks which should be reported will have to

  12. SpS1-Measuring magnetic fields on young stars

    NASA Astrophysics Data System (ADS)

    Johns-Krull, Christopher M.; Valenti, Jeff A.

    2010-11-01

    T Tauri stars (TTSs) are young (~few Myr) late type stars that have only recently emerged from their natal molecular cloud material to become visible at optical wavelengths. It is now generally accepted that accretion of circumstellar disk material onto the surface of a TTS is controlled by a strong stellar magnetic field (e.g. see review by Bouvier et al. 2007). The stellar field appears critical for explaining the rotational properties of TTSs (Bouvier et al. 2007, Herbst et al. 2007) and may also play a critical role in driving the outflows seen from many of these sources (e.g. Shang et al. 2007, Mohanty & Shu 2008). As a result, there is a great deal of interest in measuring the magnetic field properties of TTSs (e.g. Johns-Krull 2007, Donati et al. 2008). In particular, disk locking theories predict that an equilibrium is established where the disk is trunctated at or close to corotation and the stellar rotation rate depends only on the (assumed) dipolar magnetic field strength, the stellar mass, radius, and the mass accretion rate in the disk (see Bouvier et al. 2007).

  13. A geometric formulation of Higgs Effective Field Theory: Measuring the curvature of scalar field space

    NASA Astrophysics Data System (ADS)

    Alonso, Rodrigo; Jenkins, Elizabeth E.; Manohar, Aneesh V.

    2016-03-01

    A geometric formulation of Higgs Effective Field Theory (HEFT) is presented. Experimental observables are given in terms of geometric invariants of the scalar sigma model sector such as the curvature of the scalar field manifold M. We show how the curvature can be measured experimentally via Higgs cross-sections, WL scattering, and the S parameter. The one-loop action of HEFT is given in terms of geometric invariants of M. The distinction between the Standard Model (SM) and HEFT is whether M is flat or curved, and the curvature is a signal of the scale of new physics.

  14. Probe measurements of the three-dimensional magnetic field structure in a rotating magnetic field sustained field-reversed configuration

    SciTech Connect

    Velas, K. M.; Milroy, R. D.

    2014-01-15

    A translatable three-axis probe was constructed and installed on the translation, confinement, and sustainment upgrade (TCSU) experiment. With ninety windings, the probe can simultaneously measure B{sub r}, B{sub θ}, and B{sub z} at 30 radial positions, and can be placed at any desired axial position within the field reversed configuration (FRC) confinement chamber. Positioning the probe at multiple axial positions and taking multiple repeatable shots allows for a full r-z map of the magnetic field. Measurements were made for odd-parity rotating magnetic field (RMF) antennas and even-parity RMF. The steady state data from applying a 10 kHz low pass filter used in conjunction with data at the RMF frequency yields a map of the full 3D rotating field structure. Comparisons will be made to the 3D magnetic structure predicted by NIMROD simulations, with parameters adjusted to match that of the TCSU experiments. The probe provides sufficient data to utilize a Maxwell stress tensor approach to directly measure the torque applied to the FRC's electrons, which combined with a resistive torque model, yields an estimate of the average FRC resistivity.

  15. What Actually Happened.

    PubMed

    2016-07-01

    An ethics consult was scheduled for the following day. Prior to the consult, Mr. Hope subsequently decompensated and was transferred to the local hospital. The ethics consultation service continued with the ethics consult to discuss the ethical concerns of the medical staff but in particular to create an open forum for the staff to process their moral distress over the care of this patient and to come to an agreed-on plan on how they would proceed should the resident code. The patient never returned to the long-term care setting. While in the emergency room, the patient took a turn for the worse and appeared to require intubation. The emergency room attending physician contacted the patient's family and discussed the imminent likelihood of the patient's demise and the potential harm caused to the patient by resuscitation and intubation, and the family agreed to switch to comfort measures, allowing the patient to pass peacefully. The family stated to the ER physician that they needed to feel as though they had done everything they could to keep their loved one alive and did not want any responsibility for his death. The staff at the long-term care setting still remember Mr. Hope in their daily work and talk about him often. PMID:27348844

  16. Two-Photon Voltmeter for Measuring a Molecular Electric Field**

    PubMed Central

    Rebane, Aleksander; Wicks, Geoffrey; Drobizhev, Mikhail; Cooper, Thomas; Trummal, Aleksander; Uudsemaa, Merle

    2015-01-01

    We present a new approach for determining the strength of the dipolar solute-induced reaction field, along with the ground- and excited-state electrostatic dipole moments and polarizability of a solvated chromophore, using exclusively one-photon and two-photon absorption measurements. We verify the approach on two benchmark chromophores N,N-dimethyl-6-propionyl-2-naphthylamine (prodan) and coumarin 153 (C153) in a series of toluene/dimethyl sulfoxide (DMSO) mixtures and find that the experimental values show good quantitative agreement with literature and our quantum-chemical calculations. Our results indicate that the reaction field varies in a surprisingly broad range, 0–107 V cm−1, and that at close proximity, on the order of the chromophore radius, the effective dielectric constant of the solute–solvent system displays a unique functional dependence on the bulk dielectric constant, offering new insight into the close-range molecular interaction. PMID:25958849

  17. REVIEW OF HIGH FIELD Q SLOPE, CAVITY MEASUREMENTS

    SciTech Connect

    Gianluigi Ciovati

    2008-01-23

    One of the most interesting phenomenon occurring in superconducting radio-frequency (SRF) cavities made of bulk niobium is represented by a sharp decrease of the quality factor above peak surface magnetic field of about 90 mT and is referred to as "high field Q-slope" or "Q-drop". This phenomenon was observed first in 1997 and since then some effort was devoted to the understanding of the causes behind it. Still, no clear physical interpretation of the Q-drop has emerged, despite several attempts. In this contribution, I will review the experimental results for various cavities measured in many laboratories and I will try to identify common features and differences related to the Q-drop.

  18. Two-photon voltmeter for measuring a molecular electric field.

    PubMed

    Rebane, Aleksander; Wicks, Geoffrey; Drobizhev, Mikhail; Cooper, Thomas; Trummal, Aleksander; Uudsemaa, Merle

    2015-06-22

    We present a new approach for determining the strength of the dipolar solute-induced reaction field, along with the ground- and excited-state electrostatic dipole moments and polarizability of a solvated chromophore, using exclusively one-photon and two-photon absorption measurements. We verify the approach on two benchmark chromophores N,N-dimethyl-6-propionyl-2-naphthylamine (prodan) and coumarin 153 (C153) in a series of toluene/dimethyl sulfoxide (DMSO) mixtures and find that the experimental values show good quantitative agreement with literature and our quantum-chemical calculations. Our results indicate that the reaction field varies in a surprisingly broad range, 0-10(7)  V cm(-1) , and that at close proximity, on the order of the chromophore radius, the effective dielectric constant of the solute-solvent system displays a unique functional dependence on the bulk dielectric constant, offering new insight into the close-range molecular interaction. PMID:25958849

  19. Magsat vector magnetometer calibration using Magsat geomagnetic field measurements

    NASA Technical Reports Server (NTRS)

    Lancaster, E. R.; Jennings, T.; Morrissey, M.; Langel, R. A.

    1980-01-01

    From the time of its launch on Oct. 30, 1979 into a nearly polar, Sun synchronous orbit, until it reentered the Earth's atmosphere on June 11, 1980, Magsat measured and transmitted more than three complete sets of global magnetic field data. The data obtained from the mission will be used primarily to compute a currently accurate model of the Earth's main magnetic field, to update and refine world and regional magnetic charts, and to develop a global scalar and vector crustal magnetic anomaly map. The in-flight calibration procecure used for 39 vector magnetometer system parameters is described as well as results obtained from some data sets and the numerical studies designed to evaluate the results.

  20. Nonlinear propagation in ultrasonic fields: measurements, modelling and harmonic imaging.

    PubMed

    Humphrey, V F

    2000-03-01

    In high amplitude ultrasonic fields, such as those used in medical ultrasound, nonlinear propagation can result in waveform distortion and the generation of harmonics of the initial frequency. In the nearfield of a transducer this process is complicated by diffraction effects associated with the source. The results of a programme to study the nonlinear propagation in the fields of circular, focused and rectangular transducers are described, and comparisons made with numerical predictions obtained using a finite difference solution to the Khokhlov-Zabolotskaya-Kuznetsov (or KZK) equation. These results are extended to consider nonlinear propagation in tissue-like media and the implications for ultrasonic measurements and ultrasonic heating are discussed. The narrower beamwidths and reduced side-lobe levels of the harmonic beams are illustrated and the use of harmonics to form diagnostic images with improved resolution is described. PMID:10829672

  1. Full field gas phase velocity measurements in microgravity

    NASA Technical Reports Server (NTRS)

    Griffin, Devon W.; Yanis, William

    1995-01-01

    Measurement of full-field velocities via Particle Imaging Velocimetry (PIV) is common in research efforts involving fluid motion. While such measurements have been successfully performed in the liquid phase in a microgravity environment, gas-phase measurements have been beset by difficulties with seeding and laser strength. A synthesis of techniques developed at NASA LeRC exhibits promise in overcoming these difficulties. Typical implementation of PIV involves forming the light from a pulsed laser into a sheet that is some fraction of a millimeter thick and 50 or more millimeters wide. When a particle enters this sheet during a pulse, light scattered from the particle is recorded by a detector, which may be a film plane or a CCD array. Assuming that the particle remains within the boundaries of the sheet for the second pulse and can be distinguished from neighboring particles, comparison of the two images produces an average velocity vector for the time between the pulses. If the concentration of particles in the sampling volume is sufficiently large but the particles remain discrete, a full field map may be generated.

  2. Laboratory measurements on reservoir rocks from The Geysers geothermal field

    SciTech Connect

    Boitnott, G.N.

    1995-01-26

    A suite of laboratory measurements have been conducted on Geysers metagraywacke and metashale recovered from a drilled depth of 2599 to 2602 meters in NEGU-17. The tests have been designed to constrain the mechanical and water-storage properties of the matrix material. Various measurements have been made at a variety of pressures and at varying degrees of saturation. Both compressional and shear velocities exhibit relatively little change with effective confining pressure. In all of the samples, water saturation causes an increase in the compressional velocity. In some samples, saturation results in a moderate decrease in shear velocity greater in magnitude than would be expected based on the slight increase in bulk density. It is found that the effect of saturation on the velocities can be quantitatively modeled through a modification of Biot-Gassmann theory to include weakening of the shear modulus with saturation. The decrease is attributed to chemo-mechanical weakening caused by the presence of water. The degree of frame weakening of the shear modulus is variable between samples, and appears correlated with petrographic features of the cores. Two related models are presented through which we can study the importance of saturation effects on field-scale velocity variations. The model results indicate that the saturation effects within the matrix are significant and may contribute to previously observed field anomalies. The results help to define ways in which we may be able to separate the effects of variations in rock properties, caused by phenomena such as degree of fracturing, from similar effects caused by variations in matrix saturation. The need for both compressional and shear velocity data in order to interpret field anomalies is illustrated through comparisons of model results with the field observations.

  3. Whole-field geophysical measurements using coherent optics

    SciTech Connect

    Conley, E.

    1997-10-01

    This paper describes powerful methods of optics and mechanics brought to bear on important geomechanical problems. Whole-field surface glacier ice flow and mine-wall strains were mapped in two separate feasibility studies using high-resolution photography and coherent light to interrogate the images. Young`s fringe patterns result when a double-exposed transparency of a deforming surface is illuminated by a narrow beam of coherent light. Geometry gives a relationship between the surface displacement vector and the interference fringe patterns. The displacement occurring during the time-lapse interval is thus known. When applied to the surface of the Nisqually Glacier, Mt Rainier National Park, WA, the speckle method yielded ice flow data that was compared with similar flow data acquired by surveying techniques. In the areas for which results can be compared, our experiments yield a flow of .6 meters/day where conventional methods yield about .4 meters/day. The same photographic technique was applied to measure the visco-plastic deformation of a proposed nuclear waste repository carved into bedded salt deep in the earth`s crust Data reduction concluded with the differentiation of the displacement vector map to obtain the two-dimensional strain rate field which correlated well with extensometer-gathered data. The research demonstrates the feasibility of using whole-field optical techniques to map ice flow and mine-wall strains, and confirms certain, but not all, measurements of point-by-point instruments. Field work, data analysis, and additional potential applications of the speckle photography method are indicated.

  4. Comparability between various field and laboratory wood-stove emission-measurement methods

    SciTech Connect

    McCrillis, R.C.; Jaasma, D.R.

    1991-01-01

    The paper compares various field and laboratory woodstove emission measurement methods. In 1988, the U.S. EPA promulgated performance standards for residential wood heaters (woodstoves). Over the past several years, a number of field studies have been undertaken to determine the actual level of emission reduction achieved by new technology woodstoves in everyday use. The studies have required the development and use of particulate and gaseous emission sampling equipment compatible with operation in private homes. Since woodstoves are tested for certification in the laboratory using EPA Methods 5G and 5H, it is of interest to determine the correlation between these regulatory methods and the inhouse equipment. Two inhouse sampling systems have been used most widely: one is an intermittent, pump-driven particulate sampler that collects particulate and condensible organics on a filter and organic adsorbent resin; and the other uses an evacuated cylinder as the motive force and particulate and condensible organics are collected in a condenser and dual filter. Both samplers can operate unattended for 1-week periods. A large number of tests have been run comparing Methods 5G and 5H to both samplers. The paper presents these comparison data and determines the relationships between regulations and field samplers.

  5. Flow field measurements in the cell culture unit

    NASA Technical Reports Server (NTRS)

    Walker, Stephen; Wilder, Mike; Dimanlig, Arsenio; Jagger, Justin; Searby, Nancy

    2002-01-01

    The cell culture unit (CCU) is being designed to support cell growth for long-duration life science experiments on the International Space Station (ISS). The CCU is a perfused loop system that provides a fluid environment for controlled cell growth experiments within cell specimen chambers (CSCs), and is intended to accommodate diverse cell specimen types. Many of the functional requirements depend on the fluid flow field within the CSC (e.g., feeding and gas management). A design goal of the CCU is to match, within experimental limits, all environmental conditions, other than the effects of gravity on the cells, whether the hardware is in microgravity ( micro g), normal Earth gravity, or up to 2g on the ISS centrifuge. In order to achieve this goal, two steps are being taken. The first step is to characterize the environmental conditions of current 1g cell biology experiments being performed in laboratories using ground-based hardware. The second step is to ensure that the design of the CCU allows the fluid flow conditions found in 1g to be replicated from microgravity up to 2g. The techniques that are being used to take these steps include flow visualization, particle image velocimetry (PIV), and computational fluid dynamics (CFD). Flow visualization using the injection of dye has been used to gain a global perspective of the characteristics of the CSC flow field. To characterize laboratory cell culture conditions, PIV is being used to determine the flow field parameters of cell suspension cultures grown in Erlenmeyer flasks on orbital shakers. These measured parameters will be compared to PIV measurements in the CSCs to ensure that the flow field that cells encounter in CSCs is within the bounds determined for typical laboratory experiments. Using CFD, a detailed simulation is being developed to predict the flow field within the CSC for a wide variety of flow conditions, including microgravity environments. Results from all these measurements and analyses of the

  6. A miniDOAS instrument optimised for ammonia field measurements

    NASA Astrophysics Data System (ADS)

    Sintermann, Jörg; Dietrich, Klaus; Häni, Christoph; Bell, Michael; Jocher, Markus; Neftel, Albrecht

    2016-06-01

    We present a differential optical absorption spectroscopy (DOAS) instrument, called "miniDOAS", optimised for optical open-path field-measurements of ambient ammonia (NH3) alongside nitrogen oxide (NO) and sulfur dioxide (SO2). The instrument is a further development of the miniDOAS presented by Volten et al. (2012). We use a temperature-controlled spectrometer, a deuterium light source and a modified optical arrangement. The system was set up in a robust, field-deployable, temperature-regulated housing. For the evaluation of light spectra we use a new high-pass filter routine based upon robust baseline extraction with local regression. Multiple linear regression including terms of an autoregressive-moving-average model is used to determine concentrations. For NH3 the random uncertainty is about 1.4 % of the concentration, and not better than 0.2 µg m-3. Potential biases for the slope of the calibration are given by the precision of the differential absorption cross sections (±3 %) and for the offset by the precision of the estimation of concentration offsets (cref) introduced by the reference spectrum Iref. Comparisons of miniDOAS measurements to those by NH3 acid trap devices showed good agreement. The miniDOAS can be flexibly used for a wide range of field trials, such as micrometeorological NH3 flux measurements with approaches based upon horizontal or vertical concentration differences. Results from such applications covering concentration dynamics of less than one up to several hundreds of µg m-3 are presented.

  7. Field inter-comparison of eleven atmospheric ammonia measurement techniques

    NASA Astrophysics Data System (ADS)

    von Bobrutzki, K.; Braban, C. F.; Famulari, D.; Jones, S. K.; Blackall, T.; Smith, T. E. L.; Blom, M.; Coe, H.; Gallagher, M.; Ghalaieny, M.; McGillen, M. R.; Percival, C. J.; Whitehead, J. D.; Ellis, R.; Murphy, J.; Mohacsi, A.; Pogany, A.; Junninen, H.; Rantanen, S.; Sutton, M. A.; Nemitz, E.

    2010-01-01

    Eleven instruments for the measurement of ambient concentrations of atmospheric ammonia gas (NH3), based on eight different measurement methods were inter-compared above an intensively managed agricultural field in late summer 2008 in Southern Scotland. To test the instruments over a wide range of concentrations, the field was fertilised with urea midway through the experiment, leading to an increase in the average concentration from 10 to 100 ppbv. The instruments deployed included three wet-chemistry systems, one with offline analysis (annular rotating batch denuder, RBD) and two with online-analysis (Annular Denuder sampling with online Analysis, AMANDA; AiRRmonia), two Quantum Cascade Laser Absorption Spectrometers (a large-cell dual system; DUAL-QCLAS, and a compact system; c-QCLAS), two photo-acoustic spectrometers (WaSul-Flux; Nitrolux-100), a Cavity Ring Down Spectrosmeter (CRDS), a Chemical Ionisation Mass Spectrometer (CIMS), an ion mobility spectrometer (IMS) and an Open-Path Fourier Transform Infra-Red (OP-FTIR) Spectrometer. The instruments were compared with each other and with the average concentration of all instruments. An overall good agreement of hourly average concentrations between the instruments (R2>0.84), was observed for NH3 concentrations at the field of up to 120 ppbv with the slopes against the average ranging from 0.67 (DUAL-QCLAS) to 1.13 (AiRRmonia) with intercepts of -0.74 ppbv (RBD) to +2.69 ppbv (CIMS). More variability was found for performance for lower concentrations (<10 ppbv). Here the main factors affecting measurement precision are (a) the inlet design, (b) the state of inlet filters (where applicable), and (c) the quality of gas-phase standards (where applicable). By reference to the fast (1 Hz) instruments deployed during the study, it was possible to characterize the response times of the slower instruments.

  8. Field inter-comparison of eleven atmospheric ammonia measurement techniques

    NASA Astrophysics Data System (ADS)

    von Bobrutzki, K.; Braban, C. F.; Famulari, D.; Jones, S. K.; Blackall, T.; Smith, T. E. L.; Blom, M.; Coe, H.; Gallagher, M.; Ghalaieny, M.; McGillen, M. R.; Percival, C. J.; Whitehead, J. D.; Ellis, R.; Murphy, J.; Mohacsi, A.; Junninen, H.; Pogany, A.; Rantanen, S.; Sutton, M. A.; Nemitz, E.

    2009-08-01

    Eleven instruments for the measurement of ambient concentrations of atmospheric ammonia gas (NH3), based on eight different measurement methods were inter-compared above an intensively managed agricultural field in late summer 2008 in S. Scotland. To test the instruments over a wide range of concentrations, the field was fertilised with urea midway through the experiment, leading to an increase in the average concentration from 10 to 100 ppbv. The instruments deployed included three wet-chemistry systems, one with offline analysis (annular rotating batch denuder, RBD) and two with online-analysis (Annular Denuder sampling with online Analysis, AMANDA; AiRRmonia), two Quantum Cascade Laser Absorption Spectrometers (a large-cell dual system, DUAL-QCLAS, and a compact system, c-QCLAS), two photo-acoustic spectrometers (WaSul-Flux, Nitrolux-100), a Cavity Ring Down Spectrosmeter (CRDS), a Chemical Ionisation Mass Spectrometer (CIMS), an ion mobility spectrometer (IMS) and an Open-Path Fourier Transform Infra-Red (OP-FTIR) spectroscopy. Each instrument was compared with each other and with the average concentration of all instruments. An overall good agreement of hourly average concentrations between the instruments (R2>0.84), was observed for NH3 concentrations at the field of up to 120 ppbv with the slopes against the average ranging from 0.67 (DUAL-QCLAS) to 1.13 (AiRRmonia) with intercepts of -0.74 ppbv (RBD) to +2.69 ppbv (CIMS). More variability was found for performance for lower concentrations (<10 ppbv). Here the overruling factors affecting measurement precision are (a) the inlet design, (b) the state of inlet filters (where applicable), and (c) the quality of gas-phase standards (where applicable). By reference to the fast (1 Hz) instruments deployed during the study, it was possible to characterize the response times of the slower instruments.

  9. Novel Techniques for Pulsed Field Gradient NMR Measurements

    NASA Astrophysics Data System (ADS)

    Brey, William Wallace

    Pulsed field gradient (PFG) techniques 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 eddy currents in the absence of shielding, and improved use of bore space. We used an approximation technique to predict the remaining eddy 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 technique was developed to measure the remaining eddy 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 technique was also used to design an inverse filter to remove the eddy 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 techniques and coil designs will find

  10. Measuring the complex field scattered by single submicron particles

    SciTech Connect

    Potenza, Marco A. C. Sanvito, Tiziano

    2015-11-15

    We describe a method for simultaneous measurements of the real and imaginary parts of the field scattered by single nanoparticles illuminated by a laser beam, exploiting a self-reference interferometric scheme relying on the fundamentals of the Optical Theorem. Results obtained with calibrated spheres of different materials are compared to the expected values obtained through a simplified analytical model without any free parameters, and the method is applied to a highly polydisperse water suspension of Poly(D,L-lactide-co-glycolide) nanoparticles. Advantages with respect to existing methods and possible applications are discussed.

  11. System having unmodulated flux locked loop for measuring magnetic fields

    DOEpatents

    Ganther, Jr., Kenneth R.; Snapp, Lowell D.

    2006-08-15

    A system (10) for measuring magnetic fields, wherein the system (10) comprises an unmodulated or direct-feedback flux locked loop (12) connected by first and second unbalanced RF coaxial transmission lines (16a, 16b) to a superconducting quantum interference device (14). The FLL (12) operates for the most part in a room-temperature or non-cryogenic environment, while the SQUID (14) operates in a cryogenic environment, with the first and second lines (16a, 16b) extending between these two operating environments.

  12. DEVELOPMENT OF A PRECISE MAGNETIC FIELD MEASUREMENT SYSTEM FOR FAST-CHANGING MAGNETIC FIELDS.

    SciTech Connect

    WANDERER,P.; ESCALLIER,J.; GANETIS,G.; JAIN,A.; LOUIE,W.; MARONE,A.; THOMAS,R.

    2003-06-15

    Several recent applications for fast ramped magnets have been found that require precise measurement of the time-dependent fields. In one instance, accelerator dipoles will be ramped at 1 T/sec, with measurements needed to the typical level of accuracy for accelerators, {Delta} B/B better than 0.01%. To meet this need, we have begun development of a system containing 16 stationary pickup windings that will be sampled at a high rate. It is hoped that harmonics through the decapole can be measured with this system. Precise measurement of the time-dependent harmonics requires that both the pickup windings and the voltmeters be nearly identical. To minimize costs, printed circuit boards are being used for the pickup windings and a combination of amplifiers and ADC's for voltmeters. In addition, new software must be developed for the analysis. The paper will present a status report on this work.

  13. Convective Power Loss Measurements in a Field Reversed Configuration with Rotating Magnetic Field Current Drive

    NASA Astrophysics Data System (ADS)

    Melnik, Paul

    The Translation, Confinement, and Sustainment Upgrade (TCSU) experiment achieves direct formation and sustainment of a field reversed configuration (FRC) plasma through rotating magnetic fields (RMF). The pre-ionized gas necessary for FRC formation is supplied by a magnetized cascade arc source that has been developed for TCSU. To ensure ideal FRC performance, the condition of the vacuum chamber prior to RMF start-up has been characterized with the use of a fast response ion gauge. A circuit capable of gating the puff valves with initial high voltage for quick response and then indefinite operational voltage was also designed. A fully translatable combination Langmuir / Mach probe was also built to measure the electron temperature, electron density, and ion velocity of the FRC. These measurements were also successfully completed in the FRC exhaust jets allowing for an accurate analysis of the FRC power loss through convection.

  14. The Measurement of the Field of View from Airplane Cockpits

    NASA Technical Reports Server (NTRS)

    Gough, Melvin N

    1936-01-01

    A method has been devised for the angular measurement and graphic portrayal of the view obtained from the pilot's cockpit of an airplane. The assumption upon which the method is based and a description of the instrument, designated a "visiometer", used in the measurement are given. Account is taken of the fact that the pilot has two eyes and two separate sources of vision. The view is represented on charts using an equal-area polar projection, a description and proof of which are given. The use of this chart, aside from its simplicity, may make possible the establishment of simple criterions of the field of view. Charts of five representative airplanes with various cockpit arrangements are included.

  15. Measurements of Magnetic Fields in the Solar Nebula

    NASA Astrophysics Data System (ADS)

    Fu, R. R.; Andrade Lima, E.; Weiss, B. P.

    2013-12-01

    Efficient radial transfer of angular momentum in the protoplanetary disk is a fundamental requirement for the formation of stars and planets. Theoretical work indicates that magnetic fields may have played a critical role in this process. For example, the magnetorotational instability (MRI) may have generated turbulence in the gas medium to facilitate angular momentum transport. Direct measurements of the magnetic field in the protoplanetary disk are necessary for evaluating the relative importance of this and other proposed mechanisms of angular momentum transport. Such fields could have been recorded by chondrules, millimeter-sized meteoritic inclusions that formed during flash-melting of nebular dust. We performed the first detailed paleomagnetic experiments on isolated chondrules from a primitive meteorite, the LL3.0 chondrite Semarkona. This meteorite has escaped extensive post-accretional aqueous alteration and metamorphism to above ~200 C, implying the preservation of primary ferromagnetic phases and pre-accretional magnetic remanence. We applied alternating field (AF) demagnetization up to 290 mT to bulk (mixed matrix and chondrule) samples and to isolated chondrules that contain dusty olivine grains, which are relict silicates that contain abundant low-Ni α-Fe (kamacite) grains in the single domain and pseudo-single domain size ranges. All samples were mutually oriented within 5 deg. Chondrule samples were measured using the SQUID Microscope in the MIT Paleomagnetism Laboratory. Bulk samples within ~4.5 mm of the fusion crust carry a unidirectional, medium-coercivity (MC) component of magnetization that decays in intensity with increasing distance from the fusion crust. We therefore attribute the MC component to atmospheric heating. This fusion crust baked contact test establishes that our sample has not been significantly remagnetized since arrival on Earth. One dusty olivine-bearing chondrule carries a stable high-coercivity (HC) component of

  16. A comprehensive method of estimating electric fields from vector magnetic field and Doppler measurements

    SciTech Connect

    Kazachenko, Maria D.; Fisher, George H.; Welsch, Brian T.

    2014-11-01

    Photospheric electric fields, estimated from sequences of vector magnetic field and Doppler measurements, can be used to estimate the flux of magnetic energy (the Poynting flux) into the corona and as time-dependent boundary conditions for dynamic models of the coronal magnetic field. We have modified and extended an existing method to estimate photospheric electric fields that combines a poloidal-toroidal decomposition (PTD) of the evolving magnetic field vector with Doppler and horizontal plasma velocities. Our current, more comprehensive method, which we dub the 'PTD-Doppler-FLCT Ideal' (PDFI) technique, can now incorporate Doppler velocities from non-normal viewing angles. It uses the FISHPACK software package to solve several two-dimensional Poisson equations, a faster and more robust approach than our previous implementations. Here, we describe systematic, quantitative tests of the accuracy and robustness of the PDFI technique using synthetic data from anelastic MHD (ANMHD) simulations, which have been used in similar tests in the past. We find that the PDFI method has less than 1% error in the total Poynting flux and a 10% error in the helicity flux rate at a normal viewing angle (θ = 0) and less than 25% and 10% errors, respectively, at large viewing angles (θ < 60°). We compare our results with other inversion methods at zero viewing angle and find that our method's estimates of the fluxes of magnetic energy and helicity are comparable to or more accurate than other methods. We also discuss the limitations of the PDFI method and its uncertainties.

  17. Fine resolution soil water fluxes measured with a small Smart Field Lysimeter: The noise removal and further interpretation

    NASA Astrophysics Data System (ADS)

    Dolezal, Frantisek; Bekere Mekonnen, Getu; Matula, Svatopluk; Mihalikova, Marketa; Fisak, Jaroslav; Teressa Chala, Ayele; Hrkalova, Marketa; Moreira Barradas, Joao Manuel

    2014-05-01

    A weighable Smart Field Lysimeter (30 cm diameter, 30 cm depth) with an adaptively regulated suction at its bottom was used to measure soil water fluxes at the surface and at the 30 cm depth of a short grass stand. No overland flow or accumulation of water at the surface were observed and there was no groundwater table within the soil profile. Appropriate distinction between the fluxes of different directions made it possible to separately estimate actual evapotranspiration (upward surface flux), precipitation and condensation (downward surface flux and dew on grass leaves), percolation (downward flux at 30 cm) and capillary rise (upward flux at 30 cm). The primary data were collected at 1 minute intervals but required digital filtering to remove the information noise. Various methods of filtering were tested, with a special regard to intensive rain events. The resulting data have a 10-minute resolution. The lysimeter is capable of self-recovery after a period of drought but the noise of percolation and capillary rise estimates is enhanced for some time during, before and after this period. In these situations, it is important that a porous matrix sensor measures the suction in parallel to the reference tensiometer. Both the precipitation and the actual evapotranspiration derived from the lysimeter data alone are in absolute values higher than the analogous quantities obtained with the help of the directly measured tipping bucket precipitation. These discrepancies are probably due to the rain gauge underestimating true precipitation, but partly also due to numerical noise, however smoothed. If the rain gauge data are used only to distinguish the periods of rain from the rainless periods, than the condensation of water in the soil and on the grass leaves can be estimated. The actual evapotranspiration measured by the lysimeter has a diurnal patterns depending on actual weather. The maximum occurs, on average, shortly after the noon. The percolation curves after rain

  18. Vibratory strain field measurement by transverse digital holography.

    PubMed

    Stetson, Karl A

    2015-09-20

    A method is presented for measuring vibratory strain fields using phase-stepped, image-plane digital holography. An object surface is observed along its normal vector while illuminated at equal and opposite angles by two mutually coherent laser beams. One beam is phase stepped by quarter-wavelength increments between TV frames, and the resulting images are processed to yield holographic images. Object vibrations result in zero-order Bessel function fringes in the display. The second beam is modulated at the same frequency of the object vibration and is used to shift the fringes in a manner analogous to phase step interferometry. The resulting images are processed to yield a wrapped phase map, which is unwrapped and corrected for the error associated with using zero-order Bessel functions in place of cosine functions. The unwrapped images are processed to obtain the average slopes for image segments, and these slopes are multiplied by a scale factor to convert them to strain. The analysis program used here divides the field of view into five horizontal by four vertical segments, which provide a map of the vibratory strain field. PMID:26406526

  19. Ion temperature fluctuation measurements using a retarding field analyzer.

    PubMed

    Nedzelskiy, I S; Silva, C; Duarte, P; Fernandes, H

    2011-04-01

    The retarding field analyzer (RFA) is a widely used diagnostic tool for the ion temperature measurement in the scrape-off-layer (SOL) of the thermonuclear plasma devices. However, the temporal resolution in the standard RFA application is restricted to the ms timescale. In this paper, a dc operation of the RFA is considered, which allows for the measurement of the plasma ion temperature fluctuations. The method is based on the relation for the RFA current-voltage (I-V) characteristic resulted from a common RFA model of shifted Maxwellian distribution of the analyzed ions, and the measurements of two points on the exponentially decaying region of the I-V characteristic with two differently dc biased RFA electrodes. The method has been tested and compared with conventional RFA measurements of the ion temperature in the tokamak ISTTOK SOL plasma. An ion temperature of T(i) = 17 eV is obtained near the limiter position. The agreement between the results of the two methods is within ∼25%. The amplitude of the ion temperature fluctuations is found to be around 5 eV at this location. The method has been validated by taking into account the effect of fluctuations in the plasma potential and the noise contamination, proving the reliability of the results obtained. Finally, constrains to the method application are discussed that include a negligible electron emission from the RFA grids and the restriction to operate in the exponentially decaying region of the I-V characteristic. PMID:21529006

  20. Lacunarity Measures of Potential Fields in Covered Lithology Identification

    NASA Astrophysics Data System (ADS)

    Gettings, M. E.

    2013-12-01

    Measure distributions, both multifractal and other kinds, are not unique, so spatial patterns with the same measure may have different appearances. Lacunarity analysis is a method of description of dispersion in spatial patterns across a range of scales, and is one way of descriminating clustering of similar values. Lacunarity of an image was calculated using a moving window across a range of scales as the ratio of the second moment divided by the square of the first moment for values within the window. This gives a curve of lacunarity versus resolution (scale); the curve is concave for highly clustered data, pseudolinear or convex for data with clusters at many scales such as multifractal simulations, and constant for uniformly spaced data. Breaks in slope of the curve indicate scales that are important in the structure of the spatial pattern. Gravity and magnetic field anomaly data are well known to be multifractal and thus calculated lacunarities of gridded datasets have been investigated to determine if the resulting curves are a useful measure of texture of the potential field data and helpful in identifying likely lithologies at depth beneath cover. Lacunarity is often calculated on binary data, but it can also be calculated using quantitative data. The quantitative data case lacunarity measure was computed for grids using a 25 by 25 km window moving over the grid, each window overlapping the previous one by 12.5 km. The data were the aeromagnetic and isostatic gravity anomaly grids for the state of Arizona at 0.5 km grid-interval, resulting in a lacunarity curves for gravity and aeromagnetic anomaly for each of approximately 2500 windows. The open-source software R was used for plotting a map of window center locations and lacunarity curves, and the map was loaded into Google Earth, together with maps of the gravity and magnetic field anomaly, porphyry copper deposit locations, and the geological map of Arizona. Windows were selected to compare lacunarity

  1. Biomass burning fuel consumption rates: a field measurement database

    NASA Astrophysics Data System (ADS)

    van Leeuwen, T. T.; van der Werf, G. R.; Hoffmann, A. A.; Detmers, R. G.; Rücker, G.; French, N. H. F.; Archibald, S.; Carvalho, J. A., Jr.; Cook, G. D.; de Groot, W. J.; Hély, C.; Kasischke, E. S.; Kloster, S.; McCarty, J. L.; Pettinari, M. L.; Savadogo, P.; Alvarado, E. C.; Boschetti, L.; Manuri, S.; Meyer, C. P.; Siegert, F.; Trollope, L. A.; Trollope, W. S. W.

    2014-12-01

    Landscape fires show large variability in the amount of biomass or fuel consumed per unit area burned. Fuel consumption (FC) depends on the biomass available to burn and the fraction of the biomass that is actually combusted, and can be combined with estimates of area burned to assess emissions. While burned area can be detected from space and estimates are becoming more reliable due to improved algorithms and sensors, FC is usually modeled or taken selectively from the literature. We compiled the peer-reviewed literature on FC for various biomes and fuel categories to understand FC and its variability better, and to provide a database that can be used to constrain biogeochemical models with fire modules. We compiled in total 77 studies covering 11 biomes including savanna (15 studies, average FC of 4.6 t DM (dry matter) ha-1 with a standard deviation of 2.2), tropical forest (n = 19, FC = 126 ± 77), temperate forest (n = 12, FC = 58 ± 72), boreal forest (n = 16, FC = 35 ± 24), pasture (n = 4, FC = 28 ± 9.3), shifting cultivation (n = 2, FC = 23, with a range of 4.0-43), crop residue (n = 4, FC = 6.5 ± 9.0), chaparral (n = 3, FC = 27 ± 19), tropical peatland (n = 4, FC = 314 ± 196), boreal peatland (n = 2, FC = 42 [42-43]), and tundra (n = 1, FC = 40). Within biomes the regional variability in the number of measurements was sometimes large, with e.g. only three measurement locations in boreal Russia and 35 sites in North America. Substantial regional differences in FC were found within the defined biomes: for example, FC of temperate pine forests in the USA was 37% lower than Australian forests dominated by eucalypt trees. Besides showing the differences between biomes, FC estimates were also grouped into different fuel classes. Our results highlight the large variability in FC, not only between biomes but also within biomes and fuel classes. This implies that substantial uncertainties are associated with using biome-averaged values to represent FC for whole

  2. Velocity field measurements on high-frequency, supersonic microactuators

    NASA Astrophysics Data System (ADS)

    Kreth, Phillip A.; Ali, Mohd Y.; Fernandez, Erik J.; Alvi, Farrukh S.

    2016-05-01

    The resonance-enhanced microjet actuator which was developed at the Advanced Aero-Propulsion Laboratory at Florida State University is a fluidic-based device that produces pulsed, supersonic microjets by utilizing a number of microscale, flow-acoustic resonance phenomena. The microactuator used in this study consists of an underexpanded source jet that flows into a cylindrical cavity with a single, 1-mm-diameter exhaust orifice through which an unsteady, supersonic jet issues at a resonant frequency of 7 kHz. The flowfields of a 1-mm underexpanded free jet and the microactuator are studied in detail using high-magnification, phase-locked flow visualizations (microschlieren) and two-component particle image velocimetry. These are the first direct measurements of the velocity fields produced by such actuators. Comparisons are made between the flow visualizations and the velocity field measurements. The results clearly show that the microactuator produces pulsed, supersonic jets with velocities exceeding 400 m/s for roughly 60 % of their cycles. With high unsteady momentum output, this type of microactuator has potential in a range of ow control applications.

  3. Field measurement of alkalinity and pH

    USGS Publications Warehouse

    Barnes, Ivan

    1964-01-01

    The behavior of electrometric pH equipment under field conditions departs from the behavior predicted from Nernst's law. The response is a linear function of pH, and hence measured pH values may be corrected to true pH if the instrument is calibrated with two reference solutions for each measurement. Alkalinity titrations may also be made in terms of true pH. Standard methods, such as colorimetric titrations, were rejected as unreliable or too cumbersome for rapid field use. The true pH of the end point of the alkalinity titration as a function of temperature, ionic strength, and total alkalinity has been calculated. Total alkalinity in potable waters is the most important factor influencing the end point pH, which varies from 5.38 (0 ? C, 5 ppm (parts per million) HC0a-) to 4.32 (300 ppm HC0a-,35 ? C), for the ranges of variables considered. With proper precautions, the pH may be determined to =i:0.02 pH and the alkalinity to =i:0.6 ppm HCO3- for many naturally occurring bodies of fresh water.

  4. Downhole seismic noise measurements in the Beowawe geothermal field, Nevada

    SciTech Connect

    Rutledge, J.T.; Albright, J.N.; Batra, R.

    1985-01-01

    A downhole seismic noise study was conducted at The Geysers area of Chevron's Beowawe geothermal field. Four wells were acoustically monitored with sensors placed simultaneously downhole and at the wellhead. Analyses included the correlation of downhole to surficial noise characteristics, well-to-well data correlations for noise source location or direction, and testing for the presence of borehole acoustic coupling between downhole and wellhead receivers. Intrawell cross-correlations in cased or lined boreholes clearly indicate acoustic coupling between wellhead and downhole receivers. Mean-integrated power values calculated over three frequency intervals indicate that the coupled signal is in the frequency interval 30 to 85 Hz and is the dominant component of signal downhole. Surficial variations of noise intensity in the frequency interval 0.5 to 15 Hz show little relation to simultaneously monitored downhole noise integrity. Downhole noise measurement appears to be predominantly a function of near-borehole phenomena in lined or cased holes. Measurements in an uncased borehole showed good correlations with surficial variations. Interwell correlations of noise could not be found. Reservoir noise in the Beowawe field indicated by conventional geophysical surveys could not be corroborated. 8 refs., 4 figs.

  5. Antenna for Measuring Electric Fields Within the Inner Heliosphere

    NASA Technical Reports Server (NTRS)

    Sittler, Edward Charles

    2007-01-01

    A document discusses concepts for the design of an antenna to be deployed from a spacecraft for measuring the ambient electric field associated with plasma waves at a location within 3 solar radii from the solar photosphere. The antenna must be long enough to extend beyond the photoelectron and plasma sheaths of the spacecraft (expected to be of the order of meters thick) and to enable measurements at frequencies from 20 Hz to 10 MHz without contamination by spacecraft electric-field noise. The antenna must, therefore, extend beyond the thermal protection system (TPS) of the main body of the spacecraft and must withstand solar heating to a temperature as high as 2,000 C while not conducting excessive heat to the interior of the spacecraft. The TPS would be conical and its axis would be pointed toward the Sun. The antenna would include monopole halves of dipoles that would be deployed from within the shadow of the TPS. The outer potion of each monopole would be composed of a carbon-carbon (C-C) composite surface exposed to direct sunlight (hot side) and a C-C side in shadow (cold side) with yttria-stabilized zirconia spacers in-between. The hot side cannot view the spacecraft bus, while the cold side can. The booms also can be tilted to minimize heat input to spacecraft bus. This design allows one to reduce heat input to the spacecraft bus to acceptable levels.

  6. Warm Magnetic Field Measurements of LARP HQ Magnet

    SciTech Connect

    Caspi, S; Cheng, D; Deitderich, D; Felice, H; Ferracin, P; Hafalia, R; Joseph, J; Lizarazo, J; Martchevskii, M; Nash, C; Sabbi, G L; Vu, C; Schmalzle, J; Ambrosio, G; Bossert, R; Chlachidze, G; DiMarco, J; Kashikhin, V

    2011-03-28

    The US-LHC Accelerator Research Program is developing and testing a high-gradient quadrupole (HQ) magnet, aiming at demonstrating the feasibility of Nb{sub 3}Sn technologies for the LHC luminosity upgrade. The 1 m long HQ magnet has a 120 mm bore with a conductor-limited gradient of 219 T/m at 1.9 K and a peak field of 15 T. HQ includes accelerator features such as alignment and field quality. Here we present the magnetic measurement results obtained at LBNL with a constant current of 30 A. A 100 mm long circuit-board rotating coil developed by FNAL was used and the induced voltage and flux increment were acquired. The measured b{sub 6} ranges from 0.3 to 0.5 units in the magnet straight section at a reference radius of 21.55 mm. The data reduced from the numerical integration of the raw voltage agree with those from the fast digital integrators.

  7. Far-field measurements of short-wavelength surface plasmons

    SciTech Connect

    Blau, Yochai; Gjonaj, Bergin; David, Asaf; Dolev, Shimon; Shterman, Doron; Bartal, Guy

    2015-03-23

    We present direct far-field measurements of short-wavelength surface plasmon polaritons (SPP) by conventional optics means. Plasmonic wavelength as short as 231 nm was observed for 532 nm illumination on a Ag−Si{sub 3}N{sub 4} platform, demonstrating the capability to characterize SPPs well below the optical diffraction limit. This is done by scaling a sub-wavelength interferometric pattern to a far-field resolvable periodicity. These subwavelength patterns are obtained by coupling light into counter-propagating SPP waves to create a standing-wave pattern of half the SPP wavelength periodicity. Such patterns are mapped by a scattering slit, tilted at an angle so as to increase the periodicity of the intensity pattern along it to more than the free-space wavelength, making it resolvable by diffraction limited optics. The simplicity of the method as well as its large dynamic range of measurable wavelengths make it an optimal technique to characterize the properties of plasmonic devices and high-index dielectric waveguides, to improve their design accuracy and enhance their functionality.

  8. EuTEPC: measurements in gamma and neutron fields.

    PubMed

    Moro, D; Chiriotti, S

    2015-09-01

    The EuTEPC (European TEPC) is a novel spherical tissue-equivalent gas-proportional single-wire counter that has been designed and constructed at the National Laboratories of Legnaro of Italian Nuclear Physics Institute in collaboration with the University of Padova, the DLR (German Aerospace Centre) and Austrian Institute of Technology. Its peculiarity is the spherical A-150 cathode wall which is sub-divided in nine sectors. Each sector is properly and differently biased, in order to obtain a uniform electric field along the anode wire, for reaching a good isotropic response and energy resolution. The counter components can be easily replaced and reassembled including the anode wire. The counter could be used as a monitor area inside the International Space Station. This paper describes first microdosimetric measurements in (60)Co, (137)Cs and (241)Am-Be(α,n) gamma and neutron fields performed with the EuTEPC filled with pure propane gas. Measurements have been performed simulating sites sizes, ranging from 0.05 up to 0.25 mg cm(-2) in pure propane, which correspond from 0.7 up to 3.3 µm equivalent site sizes in propane-TE gas. Comparisons with some literature spectra are presented. PMID:25877529

  9. Doppler Global Velocimetry Measurements for Supersonic Flow Fields

    NASA Technical Reports Server (NTRS)

    Meyers, James F.

    2005-01-01

    The application of Doppler Global Velocimetry (DGV) to high-speed flows has its origins in the original development of the technology by Komine et al (1991). Komine used a small shop-air driven nozzle to generate a 200 m/s flow. This flow velocity was chosen since it produced a fairly large Doppler shift in the scattered light, resulting in a significant transmission loss as the light passed through the Iodine vapor. This proof-of-concept investigation showed that the technology was capable of measuring flow velocity within a measurement plane defined by a single-frequency laser light sheet. The effort also proved that velocity measurements could be made without resolving individual seed particles as required by other techniques such as Fringe- Type Laser Velocimetry and Particle Image Velocimetry. The promise of making planar velocity measurements with the possibility of using 0.1-micron condensation particles for seeding, Dibble et al (1989), resulted in the investigation of supersonic jet flow fields, Elliott et al (1993) and Smith and Northam (1995) - Mach 2.0 and 1.9 respectively. Meyers (1993) conducted a wind tunnel investigation above an inclined flat plate at Mach 2.5 and above a delta wing at Mach 2.8 and 4.6. Although these measurements were crude from an accuracy viewpoint, they did prove that the technology could be used to study supersonic flows using condensation as the scattering medium. Since then several research groups have studied the technology and developed solutions and methodologies to overcome most of the measurement accuracy limitations:

  10. Field measurements of del13C in ecosystem respiration

    NASA Astrophysics Data System (ADS)

    van Asperen, Hella; Sabbatini, Simone; Nicolini, Giacomo; Warneke, Thorsten; Papale, Dario; Notholt, Justus

    2014-05-01

    Stable carbon isotope del13C-measurements are extensively used to study ecological and biogeochemical processes in ecosystems. Above terrestrial ecosystems, atmospheric del13C can vary largely due to photosynthetic fractionation. Photosynthetic processes prefer the uptake of the lighter isotope 12C (in CO2), thereby enriching the atmosphere in 13C and depleting the ecosystem carbon. At night, when ecosystem respiratory fluxes are dominant, 13C-depleted CO2 is respired and thereby depletes the atmospheric del13C-content. Different ecosystems and different parts of one ecosystem (type of plant, leaves, and roots) fractionate and respire with a different del13C-ratio signature. By determining the del13C-signature of ecosystem respiration in temporal and spatial scale, an analysis can be made of the composition of respiratory sources of the ecosystem. A field study at a dry cropland after harvest (province of Viterbo, Lazio, Italy) was performed in the summer of 2013. A FTIR (Fourier Transform Infrared Spectrometer) was set up to continuously measure CO2-, CH4-, N2O-, CO- and del13C-concentrations. The FTIR was connected to 2 different flux measurements systems: a Flux Gradient system (sampling every half hour at 1.3m and 4.2m) and 2 flux chambers (measured every hour), providing a continuous data set of the biosphere-atmosphere gas fluxes and of the gas concentrations at different heights. Keeling plot intercept values of respiratory CO2, measured by the Flux Gradient system at night, were determined to be between -25‰ and -20‰. Keeling plot intercept values of respiratory CO2, measured by the flux chamber system, varied between -24‰ and -29‰, and showed a clear diurnal pattern, suggesting different (dominant) respiratory processes between day and night.

  11. Dose measurements in pulsed radiation fields with commercially available measuring components.

    PubMed

    Friedrich, Sabrina; Hupe, Oliver

    2016-03-01

    Dose measurements in pulsed radiation fields with dosemeters using the counting technique are known to be inappropriate. Therefore, there is a demand for a portable device able to measure the dose in pulsed radiation fields. As a detector, ionisation chambers seem to be a good alternative. In particular, using a secondary standard ionisation chamber in combination with a reliable charge-measuring system would be a good solution. The Physikalisch-Technische Bundesanstalt (PTB) uses secondary standard ionisation chambers in combination with PTB-made measuring electronics for dose measurements at its reference fields. However, for general use, this equipment is too complex. For measurements on-site, a mobile special electronic system [Hupe, O. and Ankerhold, U. Determination of ambient and personal dose equivalent for personnel and cargo security screening. Radiat. Prot. Dosim. 121: (4), 429-437 (2006)] has been used successfully. Still, for general use, there is a need for a much simpler but a just as good solution. A measuring instrument with very good energy dependence for H*(10) is the secondary standard ionisation chamber HS01. An easy-to-use and commercially available electrometer for measuring the generated charges is the UNIDOS by PTW Freiburg. Depending on the expected dose values, the ionisation chamber used can be selected. In addition, measurements have been performed by using commercially available area dosemeters, e.g. the Mini SmartION 2120S by Thermo Scientific, using an ionisation chamber and the Szintomat 6134 A/H by Automess, using a scintillation detector. PMID:26056377

  12. Redox potential - field measurements - meassured vs. expected values

    NASA Astrophysics Data System (ADS)

    Stavělová, Monika; Kovář, Martin

    2016-04-01

    Oxidation and reduction (redox) potential is an important and theoretically very well defined parameter and can be calculated accurately. Its value is determinative for management of many electrochemical processes, chemical redox technologies as well as biotechnologies. To measure the redox value that would correspond with the accuracy level of theoretical calculations in field or operational conditions is however nearly impossible. Redox is in practice measured using combined argentochloride electrode with subsequent value conversion to standard hydrogen electrode (EH). Argentochloride electrode does not allow for precise calibration. Prior to the measurement the accuracy of measurement of particular electrode can only be verified in comparative/control solution with value corresponding with oxic conditions (25°C: +220 mV argentochloride electrode, i.e.. +427 mV after conversion to EH). A commercial product of stabile comparative solution for anoxic conditions is not available and therefore not used in every day practice - accuracy of negative redox is not verified. In this presentation results of two tests will be presented: a) monitoring during dynamic groundwater sampling from eight monitoring wells at a site contaminated by chlorinated ethenes (i.e. post-oxic to anoxic conditions) and b) laboratory test of groundwater contaminated by arsenic from two sites during reaction with highly oxidized compounds of iron (ferrates) - i.e. strongly oxic conditions. In both tests a simultaneous measurement by four argentochloride electrodes was implemented - all four electrodes were prior to the test maintained expertly. The redox values of testing electrodes in a comparative solution varied by max. 6 mV. The redox values measured by four electrodes in both anoxic and oxic variant varied by tens to a hundred mV, while with growing time of test the variance of measured redox values increased in both oxic and anoxic variant. Therefore the interpretation of measured redox

  13. Mixed-Field Dosimetry of a Fast Neutron Beam at the Portuguese Research Reactor for the Irradiation of Electronic Circuits - Measurements and Calculations

    NASA Astrophysics Data System (ADS)

    Fernandes, A. C.; Gonçalves, I. C.; Marques, J. G.; Santos, J.; Ramalho, A. J. G.; Osvay, M.

    2003-06-01

    The neutron and photon fields present at the Fast Neutron Beam of RPI were simulated with MCNP-4C and measured with activation foils, TLDs and ionisation chambers. In general, there is a good agreement between calculations and measurements, although the model overestimates the thermal neutron component. Aluminum oxide TLDs were found to be promising for monitoring the photon dose in actual irradiations of circuits.

  14. Radiofrequency electromagnetic leakage fields from plastic welding machines. Measurements and reducing measures.

    PubMed

    Eriksson, A; Mild, K H

    1985-01-01

    Operators of unshielded plastic welding machines are often exposed to radiofrequency (RF) electromagnetic leakage fields that substantially exceed all present occupational standards. Measurements show that the Swedish ceiling values (SE = SH = 250 W/m2) in many cases are exceeded at distances up to 1 meter from the electrode. To reduce the stray fields to an acceptable level at the location of the operator, RF field suppression devices should be fitted to the machine. We have studied the strength and the extent of the RF leakage field under various operating conditions and also investigated different methods for reducing the leakage field. The following measurements have been performed: E- and H-field strengths as a function of distance from the electrode, and as a function of load/tuning; the time dependence of [E]2 for various combinations of tuning and welding times producing a welding seam with the same strength; isopower density curves for SE and SH = 250 W/m2 with different types of RF emission control devices fitted to the machine; the RF voltage between the electrode and the welding table and the RF voltage on the machine casing. By decreasing the RF power and increasing the welding time the field strengths at the location of the operator can be reduced to levels below the ceiling values. The RF voltage between the electrode and the welding table ranged from 800 V up to 2100 V for the different plastic material that was welded. The RF voltage on certain parts on the chassis could be as high as 200 V. In order to reduce these voltages and the stray fields the machine should be equipped with a "large capacitive shield" in cases where this is possible. PMID:3850131

  15. Indirect Field Measurement of Wine-Grape Vineyard Canopy Leaf Area Index

    NASA Technical Reports Server (NTRS)

    Johnson, Lee F.; Pierce, Lars L.; Skiles, J. W. (Technical Monitor)

    2002-01-01

    Leaf area index (LAI) indirect measurements were made at 12 study plots in California's Napa Valley commercial wine-grape vineyards with a LI-COR LI-2000 Plant Canopy Analyzer (PCA). The plots encompassed different trellis systems, biological varieties, and planting densities. LAI ranged from 0.5 - 2.25 sq m leaf area/ sq m ground area according to direct (defoliation) measurements. Indirect LAI reported by the PCA was significantly related to direct LAI (r(exp 2) = 0.78, p less than 001). However, the PCA tended to underestimate direct LAI by about a factor of two. Narrowing the instrument's conical field of view from 148 deg to 56 deg served to increase readings by approximately 30%. The PCA offers a convenient way to discern relative differences in vineyard canopy density. Calibration by direct measurement (defoliation) is recommended in cases where absolute LAI is desired. Calibration equations provided herein may be inverted to retrieve actual vineyard LAI from PCA readings.

  16. Characterization of magnetic field profiles at RFX-mod by Faraday rotation measurements

    NASA Astrophysics Data System (ADS)

    Auriemma, Fulvio; Brombin, Matteo; Canton, Alessandra; Giudicotti, Leonardo; Innocente, Paolo; Zilli, Enrico

    2009-11-01

    A multichannel far-infrared (FIR, λ=118.8 μm) polarimeter has been recently upgraded and re-installed on RFX-mod to measure the Faraday rotation angle along five vertical chords. Polarimetric data, associated with electron density profile, allow the reconstruction of the poloidal magnetic field profile. In this work the setup of the diagnostic is presented and the first Faraday rotation measurements are analyzed. The measurements have been performed at plasma current above 1.2 MA and electron density between 2 and 6x10^19 m-3. The actual S/N ratio is slightly lower than the expected one, due to electromagnetic coupling of the detectors with the saddle coils close to the polarimeter position. Due to this limit, only average information in the flat-top phase of the discharge could be so far obtained. The experimental data have been compared with the result of the μ&p equilibrium model [1], showing a good agreement between experiment and model, whereas the main differences are in the external region of the plasma. A different parameterization of the μ=μ0 J.B/B^2 profile has been proposed to enhance the agreement between model and experiment. [0pt] [1] Ortolani and Snack, World Scientific (1993) Singapore

  17. Development and use of a spherical microphone array for measurement of spatial properties of reverberant sound fields

    NASA Astrophysics Data System (ADS)

    Gover, Bradford Noel

    The problem of hands-free speech pick-up is introduced, and it is identified how details of the spatial properties of the reverberant field may be useful for enhanced design of microphone arrays. From this motivation, a broadly-applicable measurement system has been developed for the analysis of the directional and spatial variations in reverberant sound fields. Two spherical, 32-element arrays of microphones are used to generate narrow beams over two different frequency ranges, together covering 300--3300 Hz. Using an omnidirectional loudspeaker as excitation in a room, the pressure impulse response in each of 60 steering directions is measured. Through analysis of these responses, the variation of arriving energy with direction is studied. The system was first validated in simple sound fields in an anechoic chamber and in a reverberation chamber. The system characterizes these sound fields as expected, both quantitatively through numerical descriptors and qualitatively from plots of the arriving energy versus direction. The system was then used to measure the sound fields in several actual rooms. Through both qualitative and quantitative output, these sound fields were seen to be highly anisotropic, influenced greatly by the direct sound and early-arriving reflections. Furthermore, the rate of sound decay was not independent of direction, sound being absorbed more rapidly in some directions than in others. These results are discussed in the context of the original motivation, and methods for their application to enhanced speech pick-up using microphone arrays are proposed.

  18. Measurements of Electric Field Fluctuations Using a Capacitive Probe on the MST Reversed Field Pinch

    NASA Astrophysics Data System (ADS)

    Tan, Mingsheng; Almagri, A. F.; Sarff, J. S.; McCollam, K. J.; Triana, J. C.; Li, H.; Ding, W. X.; Liu, W.

    2015-11-01

    Experimental measurements and extended MHD computation reveal that both flow and current density fluctuations are important for the magnetic relaxation of RFP plasmas via tearing fluctuations. Motivated by these results, we have developed a multi-electrode capacitive probe for radial profile measurements of the electrostatic potential deep in the plasma. The capacitive probe measures the ac plasma potential via electrodes insulated from the plasma using an annular boron nitride dielectric (also the particle shield), provided the secondary emission is sufficiently large (Te>20 eV). The probe has ten sets of four capacitors with 1.5 cm radial separation. At each radius, four capacitors are arranged on a 1.3 cm square grid. This probe has been inserted up to 15 cm from the wall in 200 kA deuterium plasmas. The fluctuation amplitudes increase during the sawtooth crash and the power spectrum broadens (similar to the behavior of magnetic field fluctuations). The frequency bandwidth allows measurements of the radial coherence and phase of the fluctuations associated with rotating tearing modes up to the Alfvénic range. A next-step goal is measurement of the total dynamo emf, ~ < E ~ . B ~ > /B0 , to complement ongoing measurements of the Hall dynamo emf, < J ~ × B ~ > / ne , using a deep-insertion magnetic probe. M. Tan is supported by ITER-China Program. Work is supported by US DOE.

  19. Real exposure: Field measurement of chemical plumes in headwater streams

    NASA Astrophysics Data System (ADS)

    Edwards, David D.

    In fluvial systems, organismic exposure to nonpoint source pollutants will fluctuate in frequency (exposure events), intensity (concentration), and duration. The reliance on lethal concentrations and static exposure in many laboratory studies does not adequately represent nor address exposure to in situ chemical plumes of fluvial habitats. In order to adequately address field exposure in a lab setting, one needs an understanding of the physics of chemical transmission within moving fluids. Because of the chaotic nature of turbulence, chemical plumes introduced to fluvial systems have a spatial and temporal microstructure with fluxes in chemical concentration. Consequently, time-averaged static exposure models are not ecologically relevant for the major reason of in situ distribution. The purpose of this study was to quantify in situ chemical distribution and dispersion within two physically different streams. Dopamine was introduced as a chemical tracer mimicking groundwater runoff. Chemical fluxes and stream hydrodynamics were simultaneously measured using a microelectrode and an acoustic doppler velocimeter (ADV), respectively, at three heights of three downstream locations at each research site. Fine-scale measurements of the dopamine plume microstructure showed organisms could be exposed to chemical fluctuations where concentrations are significantly greater than the overall time-averaged concentration. These measurements demonstrate that rather than relying on static exposure, standards for pollution need to consider the concept of exposure being interdependently linked to flow of the fluid medium. The relationship between fluid dynamics, pollution exposure and organism physiology are complex and need to be evaluated in ways to mimic natural systems.

  20. Thomson scattering measurements in the RFX reversed field pinch

    SciTech Connect

    Bassan, M.; Bilato, R.; Giudicotti, L.; Pasqualotto, R.; Sardella, A.

    1997-01-01

    The first systematic measurements of the electron temperature (T{sub e}) spatial profile have been obtained in the reversed field pinch experiment RFX with a single pulse Thomson scattering (TS) diagnostic. Scattered light from a ruby laser pulse (E{le}15 J, {Delta}t=30 ns) is collected through three objectives from 10 positions along a diameter in the plasma equatorial plane, with a spatial resolution of 2.5 cm. Plasma discharges with current in the range 700{endash}900 kA have been investigated finding evidence of a quite flat T{sub e} profile. Data dispersion significantly greater than experimental uncertainties provides an indication of remarkable plasma fluctuations. Results are in good agreement with T{sub e} measurements from other single chord spectroscopic diagnostics (SiLi detector and SXR double filter), showing a reliable operation down to an electron density n{sub e}=3{times}10{sup 19} m{sup {minus}3}. Integration of this apparatus with a ND:YLF laser system for multipulse Thomson scattering measurements, sharing the same input optics, is under way. {copyright} {ital 1997 American Institute of Physics.}

  1. Field measurements of sonic boom penetration into the ocean

    PubMed

    Sohn; Vernon; Hildebrand; Webb

    2000-06-01

    Six sonic booms, generated by F-4 aircraft under steady flight at a range of altitudes (610-6100 m) and Mach numbers (1.07-1.26), were measured just above the air/sea interface, and at five depths in the water column. The measurements were made with a vertical hydrophone array suspended from a small spar buoy at the sea surface, and telemetered to a nearby research vessel. The sonic boom pressure amplitude decays exponentially with depth, and the signal fades into the ambient noise field by 30-50 m, depending on the strength of the boom at the sea surface. Low-frequency components of the boom waveform penetrate significantly deeper than high frequencies. Frequencies greater than 20 Hz are difficult to observe at depths greater than about 10 m. Underwater sonic boom pressure measurements exhibit excellent agreement with predictions from analytical theory, despite the assumption of a flat air/sea interface. Significant scattering of the sonic boom signal by the rough ocean surface is not detected. Real ocean conditions appear to exert a negligible effect on the penetration of sonic booms into the ocean unless steady vehicle speeds exceed Mach 3, when the boom incidence angle is sufficient to cause scattering on realistic open ocean surfaces. PMID:10875353

  2. Measurement of tidal current fields with SRTM along track interferometry

    NASA Astrophysics Data System (ADS)

    Runge, H.; Breit, H.; Eineder, M.; Flament, P.; Romeiser, R.

    2003-04-01

    Although the Shuttle Radar Topography Mission (SRTM, http://www.dfd.dlr.de/srtm/) SAR interferometer was designed to deliver Digital Elevation Models from across track interferometry it turned out that it contained also an Along Track Interferometer (ATI). The paper describes how the ATI can be used to determine the velocity of moving ground objects. These may be cars, trains and ships but the focus of the paper is on the measurement of fast tidal ocean surface currents. The big advantage of the SAR-ATI method over buoys is that the measurement covers a large area and "images" of surface currents can be obtained.The advatage over the well established altimeter measurements is the much higher geometrical resolution and that it works close to coasts and in river outflows. Finally, the advantages over coastal radars is that a spaceborne system can deliver data from round the world. In the paper the results from two test sites, near Brest in France and in the Dutch Waddenzee, will be presented. Comparisons of the SRTM current fields with available current models of these areas show both a very good agreement. The ATI-method will be used in future SAR missions like TerraSAR-X to provide high resolution current maps from many interesting parts of the world.

  3. Field Measurements of Sonic Boom Penetration Into the Ocean

    NASA Technical Reports Server (NTRS)

    Sohn, R. A.; Vernon, F.; Hildebrand, J. A.; Webb, S. C.; Shepherd, Kevin (Technical Monitor)

    2000-01-01

    Six sonic booms, generated by F-4 aircraft under steady fight at a range of altitudes (610-6100 m) and Mach numbers (1.07-1.26), were measured just above the air/sea interface, and at five depths in the water column. The measurements were made with a vertical hydrophone array suspended from a small spar buoy at the sea surface, and telemetered to a nearby research vessel. The sonic boom pressure amplitude decays exponentially with depth, and the signal fades into the ambient noise field by 30-50 in, depending on the strength of the boom at the sea surface. Low-frequency components of the boom waveform penetrate significantly deeper than high frequencies. Frequencies greater than 20 Hz are difficult to observe at depths greater than about 10 m. Underwater sonic boom pressure measurements exhibit excellent agreement with predictions from analytical theory, despite the assumption of a flat air/sea interface. Significant scattering of the sonic boom signal by the rough ocean surface is not detected. Real ocean conditions appear to exert a negligible effect on the penetration of sonic booms into the ocean unless steady vehicle speeds exceed Mach 3, when the boom incidence angle is sufficient to cause scattering on realistic open ocean surfaces.

  4. Field Measurements of Respiratory Del13CO2 and Photodegradation

    NASA Astrophysics Data System (ADS)

    van Asperen, H.; Sabbatini, S.; Nicolini, G.; Warneke, T.; Papale, D.; Notholt, J.

    2014-12-01

    Carbon decomposition dynamics have been studied in a variety of ecosystems and its variation can mostly be explained in terms of environmental variables (e.g. temperature and precipitation). However, carbon dynamics in arid, water limited regions have shown to be very different and are still largely unknown. Several studies have indicated the importance of photodegradation, the direct breakdown of organic matter by sunlight, in these arid regions. A FTIR (Fourier Transform Infrared Spectrometer) was set up to continuously measure concentrations of CO2, CH4, N2O, CO as well as del13C in CO2. The FTIR was connected to 2 different flux measurement systems: a Flux Gradient system and 2 flux chambers, providing a continuous data set of gas concentrations and biosphere-atmosphere gas fluxes at different heights and scales. Field measurements showed photodegradation induced carbon fluxes. Also, respiratory del13CO2 was determined by use of Keeling plots, and was determined to vary between -25‰ and -21‰. A clear diurnal pattern in respiratory del13CO2 was found, suggesting either different (dominant) respiratory processes between day and night or the effect of diffusive fractionation.

  5. Field temperature measurements at Erta'Ale Lava Lake, Ethiopia

    NASA Astrophysics Data System (ADS)

    Burgi, Pierre-Yves; Caillet, Marc; Haefeli, Steven

    2002-06-01

    The shield volcano Erta'Ale, situated in the Danakil Depression, Ethiopia, is known for its active lava lake. In February 2001, our team visited this lake, located inside an 80-m-deep pit, to perform field temperature measurements. The distribution and variation of temperature inside the lake were obtained on the basis of infrared radiation measurements performed from the rim of the pit and from the lake shores. The crust temperature was also determined from the lake shores with a thermocouple to calibrate the pyrometer. We estimated an emissivity of the basalt of 0.74 from this experiment. Through the application of the Stefan-Boltzmann law, we then obtained an estimate of the total radiative heat flux, constrained by pyrometer measurements of the pit, and visual observations of the lake activity. Taking into account the atmospheric convective heat flux, the convected magma mass flux needed to balance the energy budget was subsequently derived and found to represent between 510 and 580 kg s-1. The surface circulation of this mass flux was also analyzed through motion processing techniques applied to video images of the lake. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00445-002-0224-3.

  6. Measurement of two-dimensional Doppler wind fields using a field widened Michelson interferometer.

    PubMed

    Langille, Jeffery A; Ward, William E; Scott, Alan; Arsenault, Dennis L

    2013-03-10

    An implementation of the field widened Michelson concept has been applied to obtain high resolution two-dimensional (2D) images of low velocity (<50 m/s) Doppler wind fields in the lab. Procedures and techniques have been developed that allow Doppler wind and irradiance measurements to be determined on a bin by bin basis with an accuracy of less than 2.5 m/s from CCD images over the observed field of view. The interferometer scanning mirror position is controlled to subangstrom precision with subnanometer repeatability using the multi-application low-voltage piezoelectric instrument control electronics developed by COM DEV Ltd.; it is the first implementation of this system as a phase stepping Michelson. In this paper the calibration and characterization of the Doppler imaging system is described and the planned implementation of this new technique for imaging 2D wind and irradiance fields using the earth's airglow is introduced. Observations of Doppler winds produced by a rotating wheel are reported and shown to be of sufficient precision for buoyancy wave observations in airglow in the mesopause region of the terrestrial atmosphere. PMID:23478764

  7. Electric field and plasma density measurements in the auroral electrojet

    NASA Astrophysics Data System (ADS)

    Pfaff, R. F.; Kelley, M. C.; Fejer, B. G.; Kudeki, E.; Carlson, C. W.; Pedersen, A.; Hausler, B.

    1984-01-01

    Extensive experimental and theoretical studies of auroral and equatorial electrojet irregularities have been conducted for the last two decades. The present investigation is concerned with electric field and plasma density fluctuation measurements made on board of the Porcupine II sounding rocket and on a free-flyer ejected from the main spacecraft. The Porcupine II sounding rocket payload was launched at 1922:00 UT from Kiruna, Sweden, on March 20, 1977. The considered results show electrostatic turbulence in the unstable auroral E region confined to a layer between 96 and 121 km. The similarities between the observations of two simultaneous payloads spaced a few kilometers apart indicate that on a large scale, the electrojet turbulence displays uniform characteristics.

  8. Field measurements of the spectral response of natural waters

    NASA Technical Reports Server (NTRS)

    Bartolucci, L. A.; Robinson, B. F.; Silva, L. F.

    1977-01-01

    The spectral response (air-water interface reflectance and water-volume scattering) of turbid river water (99 mg/liter suspended solids) and relatively clear lake water (10 mg/liter suspended solids) was measured in situ with a field spectroradiometer. The influence of the river bottom on the spectral response of the water also was determined by using a modified Secchi disc approach. The results indicated that turbid river water had a higher spectral response than clear lake water (about 6 percent) in the red (0.6-0.7 micron) and near-infrared (0.7-0.9 micron) portions of the spectrum. Also, the reflectance characteristics of the river bottom did not influence the spectral response of the turbid river water when the water was deeper than 30 cm

  9. A field-deployable digital acoustic measurement system

    NASA Technical Reports Server (NTRS)

    Gray, David L.; Wright, Kenneth D., II; Rowland, Wayne D.

    1991-01-01

    A field deployable digital acoustic measurement system was developed to support acoustic research programs at the Langley Research Center. The system digitizes the acoustic inputs at the microphone, which can be located up to 1000 feet from the van which houses the acquisition, storage, and analysis equipment. Digitized data from up to 12 microphones is recorded on high density 8mm tape and is analyzed post-test by a microcomputer system. Synchronous and nonsynchronous sampling is available with maximum sample rates of 12,500 and 40,000 samples per second respectively. The high density tape storage system is capable of storing 5 gigabytes of data at transfer rates up to 1 megabyte per second. System overall dynamic range exceeds 83 dB.

  10. Far-field measurements of vortex beams interacting with nanoholes.

    PubMed

    Zambrana-Puyalto, Xavier; Vidal, Xavier; Fernandez-Corbaton, Ivan; Molina-Terriza, Gabriel

    2016-01-01

    We measure the far-field intensity of vortex beams going through nanoholes. The process is analyzed in terms of helicity and total angular momentum. It is seen that the total angular momentum is preserved in the process, and helicity is not. We compute the ratio between the two transmitted helicity components, γm,p. We observe that this ratio is highly dependent on the helicity (p) and the angular momentum (m) of the incident vortex beam in consideration. Due to the mirror symmetry of the nanoholes, we are able to relate the transmission properties of vortex beams with a certain helicity and angular momentum, with the ones with opposite helicity and angular momentum. Interestingly, vortex beams enhance the γm,p ratio as compared to those obtained by Gaussian beams. PMID:26911547

  11. An instrument for measuring thermal inertia in the field

    NASA Technical Reports Server (NTRS)

    Marsh, S. E.; Schieldge, J. P.; Kahle, A. B.

    1982-01-01

    Features and test results of a thermal inertial meter (TIM) for cataloging the thermal inertial of surface material in situ as a basis for satellite remote sensing of geologic materials are described. The instrument is employed to determine the temperature rise of the materials in the field, with the assumptions that the sample and a standard are homogeneous in composition, the heat flux density is constant at the surface of each material, and the specimens are thick enough to be treated as semi-infinite bodies. A formula for calculating thermal inertia is presented, and the components of the TIM are detailed. A box with three compartments, two holding standards, is placed on the sample surface with the third compartment open to the specimen. Dolomite and quartz are used as references when all samples are measured after heating. Tests with rocks and sand in Nevada and California revealed that chert has a higher thermal inertia than barite.

  12. Extendible-retractable electric field measurement antenna for IMP J

    NASA Technical Reports Server (NTRS)

    Larrick, W.

    1973-01-01

    An antenna dispenser mechanism for the IMP J spacecraft was designed, fabricated, and tested. Upon command the mechanism deploys or retracts a conductor for use as a receiving antenna for an electric field measurement experiment. Five identical units were fabricated and tested to the IMP H & J environmental test specification. Of these, four are designated for flight on the IMP J spacecraft and one as a prototype flight spare. The testing program was successfully completed although certain design modifications were required as problems were uncovered by the testing; particularly thermal vacuum operation. The antenna mechanism functions well under the expected environmental and loading conditions. The wear life and load capability of the dry molybdenum disulphide lubricant originally used on the heavily loaded worm and gear pair were disappointing and a substitute material was applied. The lubricant finally applied performed well; although other problems were generated.

  13. Cloud Physics Lidar Measurements During the SAFARI-2000 Field Campaign

    NASA Technical Reports Server (NTRS)

    McGill, Matthew; Hlavka, Dennis; Hart, William; Spinhirne, James; Scott, Stan; Starr, David OC. (Technical Monitor)

    2001-01-01

    A new remote sensing instrument, the Cloud Physics Lidar (CPL) has been built for use on the ER-2 aircraft. The first deployment for CPL was the SAFARI-2000 field campaign during August-September 2000. The CPL is a three-wavelength lidar designed for studies of cirrus, subvisual cirrus, and boundary layer aerosols. The CPL utilizes a high repetition rate, low pulse energy laser with photon counting detectors. A brief description of the CPL instrument will be given, followed by examples of CPL data products. In particular, examples of aerosol backscatter, including boundary layer smoke and cirrus clouds will be shown. Resulting optical depth estimates derived from the aerosol measurements will be shown. Comparisons of the CPL optical depth and optical depth derived from microPulse Lidar and the AATS-14 sunphotomer will be shown.

  14. Debye size microprobes for electric field measurements in laboratory plasmas

    SciTech Connect

    Pribyl, P.; Gekelman, W.; Nakamoto, M.; Lawrence, E.; Chiang, F.; Stillman, J.; Judy, J.; Katz, N.; Kintner, P.; Niknejadi, P.

    2006-07-15

    Microelectromechanical systems (MEMS) have led to the development of a host of tiny machines and sensors over the past decade. Plasma physics is in great need of small detectors for several reasons. First of all, very small detectors do not disturb a plasma, and secondly some detectors can only work because they are very small. We report on the first of a series of small (sub-Debye length) probes for laboratory plasmas undertaken at the basic Plasma Science Facility at UCLA. The goal of the work is to develop robust and sensitive diagnostic probes that can survive in a plasma. The probes must have electronics packages in close proximity. We report on the construction and testing of probes that measure the electric field.

  15. Far-field measurements of vortex beams interacting with nanoholes

    PubMed Central

    Zambrana-Puyalto, Xavier; Vidal, Xavier; Fernandez-Corbaton, Ivan; Molina-Terriza, Gabriel

    2016-01-01

    We measure the far-field intensity of vortex beams going through nanoholes. The process is analyzed in terms of helicity and total angular momentum. It is seen that the total angular momentum is preserved in the process, and helicity is not. We compute the ratio between the two transmitted helicity components, γm,p. We observe that this ratio is highly dependent on the helicity (p) and the angular momentum (m) of the incident vortex beam in consideration. Due to the mirror symmetry of the nanoholes, we are able to relate the transmission properties of vortex beams with a certain helicity and angular momentum, with the ones with opposite helicity and angular momentum. Interestingly, vortex beams enhance the γm,p ratio as compared to those obtained by Gaussian beams. PMID:26911547

  16. GLOBAL ELECTROMAGNETIC RADIATION POLLUTION: RISK ASSESSMENT FROM FIELD MEASUREMENTS AND ANIMAL EXPERIMENTS

    NASA Astrophysics Data System (ADS)

    Fragkopoulou, A. F.; Margaritis, L. H.

    2009-12-01

    The extended use of wireless technology throughout the globe in almost all developed and non-developed countries has forced a large number of scientists to get involved in the investigation of the effects. The major issue is that unlike other forms of radiation exposure, this “non-ionizing electromagnetic radiation” was not present throughout the evolution of life in earth and therefore there are no adaptive mechanisms evolved. All organisms are vulnerable to the possible effects of radiation depending on the actual exposure level. “Safety limits” on the power density have been proposed but ongoing research has shown that these limits are not really safe for humans, not mentioning the entire population of living creatures on earth. The so called “Electrosmog Pollution” originating from the numerous radio and TV stations, communication satellite emission, but most importantly from mobile phone mast antennas, are of major concern, because it is gradually increasing at exponential rate. Therefore the key question is, do living organisms react upon their exposure to fields of non ionizing electromagnetic radiation? To have this question answered extensive research is being performed in various laboratories. One approach of our research includes field measurements within houses and classrooms, since a considerable proportion of the population in each country is exposed to the radiation coming from the nearby mast stations, in order to make a risk assessment. The measurements showed that in many cases the actual radiation present was potentially harmful. In other words, although the measured values were below the national safety levels, nevertheless they were above the levels of other countries. Therefore it has been suggested that a new cellular network should be constructed in order to minimize radiation levels in living areas and schools. Our experimental work is focusing on the elucidation of the effects of non-ionizing EMFs on mice exposed to mobile

  17. Chemical, Biological, and Explosive Sensors for Field Measurements

    SciTech Connect

    Kevin Kyle, Manuel Manard, Stephan Weeks

    2009-01-31

    Special Technologies Laboratory (STL) is developing handheld chemical, biological, and explosive (CBE) detection systems and sensor motes for wireless networked field operations. The CBE sensors are capable of detecting and identifying multiple targeted toxic industrial chemicals (TICs) and high-explosive vapor components. The CBE devices are based on differential mobility spectrometry (DMS) coupled with fast gas chromatography (GC) or mass spectrometry. The systems all include the concepts of: 1. Direct air/particulate “smart” sampling 2. Selective, continuous real-time (~1 sec) alert monitoring using DMS 3. Highly selective, rapid dual technology separation/verification analysis The biosensor technology is based on Raman aerosol particle flow cytometry for target detection and identification. Monitoring and identifying trace level chemical vapors directly from ambient air will allow First Responders to quickly adapt situational response strategies and personal protective equipment needs to the specific response scenario being encountered. First Responders require great confidence in the measurements and ability of a given system to detect CBE below threshold levels without interferences. The concept of determining the background matrix in near real-time to allow subsequent automated field-programmable method selection and cueing of high-value assets in a wide range of environs will be presented. This provides CBE information for decisions prior to First Responders entering the response site or sending a portable mobile unit for a remote site survey of the hazards. The focus is on real-time information needed by those responsible for emergency response and national security.

  18. Force field measurements within the exclusion zone of water.

    PubMed

    Chen, Chi-Shuo; Chung, Wei-Ju; Hsu, Ian C; Wu, Chien-Ming; Chin, Wei-Chun

    2012-01-01

    Water molecules play critical roles in many biological functions, such as protein dynamics, enzymatic activities, and cellular responses. Previous nuclear magnetic resonance and neutron scattering studies have shown that water molecules bind to specific sites on surfaces and form localized clusters. However, most current experimental techniques cannot measure dynamic behaviors of ordered water molecules on cell-size (10 μm) scale. Recently, the long-distance effect of structured water has been demonstrated by Pollack and his colleagues. Namely, there is a structured water layer near the hydrophilic surface that can exclude solutes (Zheng et al, Adv Colloid Interface Sci 127:19-27, 2006; Pollack 2006, Adv Colloid Interface Sci 103:173-196, 2003). The repelling forces of water clusters inside this exclusion region are investigated in this study. With a laser tweezers system, we found the existence of an unexpected force fields inside the solute-free exclusion zone near a Nafion surface. Our results suggest that the water clusters could transduce mechanical signals on the micrometer range within the exclusion zone. This unexpected inhomogeneous force field near the hydrophilic surface would provide a new insight into cellular activities, leading to a potential new physical chemistry mechanism for cell biology. PMID:23277674

  19. Field measurements in the wake of a model wind turbine

    NASA Astrophysics Data System (ADS)

    Pol, Suhas; Taylor, Amelia; Bilbao, Argenis; Doostalab, Ali; Novoa, Santiago; Westergaard, Carsten; Hussain, Fazle; Sheng, Jian; Ren, Beibei; Giesselmann, Michael; Glauser, Mark; Castillo, Luciano

    2014-06-01

    As a first step to study the dynamics of a wind farm' we experimentally explored the flow field behind a single wind turbine of diameter 1.17 m at a hub height of 6.25 m. A 10 m tower upstream of the wind farm characterizes the atmospheric conditions and its influence on the wake evolution. A vertical rake of sonic anemometers is clustered around the hub height on a second tower' 6D downstream of the turbine. We present preliminary observations from a 1- hour block of data recorded in near-neutral atmospheric conditions. The ratio of the standard deviation of power to the inflow velocity is greater than three' revealing adverse effects of inflow turbulence on the power and load fluctuations. Furthermore' the wake defect and Reynolds stress and its gradient are pronounced at 6D. The flux of energy due to Reynolds stresses is similar to that reported in wind tunnel studies. The swirl and mixing produces a constant temperature wake which results in a density jump across the wake interface. Further field measurements will explore the dynamics of a model wind farm' including the effects of atmospheric variability.

  20. Measuring Fast Ion Losses in a Reversed Field Pinch Plasma

    NASA Astrophysics Data System (ADS)

    Bonofiglo, P. J.; Anderson, J. K.; Almagri, A. F.; Kim, J.; Clark, J.; Capecchi, W.; Sears, S. H.

    2015-11-01

    The reversed field pinch (RFP) provides a unique environment to study fast ion confinement and transport. The RFP's weak toroidal field, strong magnetic shear, and ability to enter a 3D state provide a wide range of dynamics to study fast ions. Core-localized, 25 keV fast ions are sourced into MST by a tangentially injected hydrogen/deuterium neutral beam. Neutral particle analysis and measured fusion neutron flux indicate enhanced fast ion transport in the plasma core. Past experiments point to a dynamic loss of fast ions associated with the RFP's transition to a 3D state and with beam-driven, bursting magnetic modes. Consequently, fast ion transport and losses in the RFP have garnered recent attention. Valuable information on fast-ion loss, such as energy and pitch distributions, are sought to provide a better understanding of the transport mechanisms at hand. We have constructed and implemented two fast ion loss detectors (FILDs) for use on MST. The FILDs have two, independent, design concepts: collecting particles as a function of v⊥ or with pitch greater than 0.8. In this work, we present our preliminary findings and results from our FILDs on MST. This research is supported by US DOE.

  1. Insights into lateral marsh retreat mechanism through localized field measurements

    NASA Astrophysics Data System (ADS)

    Bendoni, M.; Mel, R.; Solari, L.; Lanzoni, S.; Francalanci, S.; Oumeraci, H.

    2016-02-01

    Deterioration of salt marshes may be due to several factors related to increased anthropic pressure, sea level rise, and erosive processes. While salt marshes can reach equilibrium in the vertical direction, adapting to sea level rise, they are inherently unstable in the horizontal direction. Marsh boundaries are characterized by scarps with bare sediment below the vegetated surface layer that can be easily removed by wave-induced erosion. In this work, we explore the different mechanisms involved in the erosion of marsh borders through the interpretation of field data. The analysis is based on a systematic field monitoring of a salt marsh in the Venice Lagoon subject to lateral erosion. Measurements included horizontal retreat of the scarp at various locations and wave height in front of the marsh during three storm surges. Continuous erosion and mass failures alternated during the observed period, leading to an average retreat up to 80 cm/yr. The data, collected roughly every month for 1.5 year, indicate that the linear relation that links the observed erosion rate to the impinging wave power exhibits a larger slope than that already estimated in literature on the basis of long-term surveys. Moreover, an increase in the gradient of erodibility is detected along the marsh scarp, due to the combined action of soil strengthening by vegetation on the marsh surface and the impact of wave breaking at the bank toe, which promote cantilever failures and increase the lateral erosion rate.

  2. Measurement of evapotranspiration in a winter wheat field

    NASA Astrophysics Data System (ADS)

    Zhang, Yongqiang; Liu, Changming; Shen, Yanjun; Kondoh, A.; Tang, Changyuan; Tanaka, T.; Shimada, J.

    2002-10-01

    Daily evapotranspiration from a winter wheat field on the North China Plain measured by large-scale weighing lysimeter was linearly related to that measured by the Bowen ratio energy balance (BREB) technique. Soil evaporation averaged about 23·6% of evapotranspiration from the post-winter dormancy revival stage to the grain ripening stage in 1999. On clear days during winter dormancy, about half of the net radiation flux Rn was used to warm soil. During the revival stage, conductive heat flux G also used most of the incoming Rn, but the ratio of latent heat flux E to Rn increased. During the stem-extension stage, E was about 50% of Rn; thereafter, E/Rfield conditions. However, we observed that there exists a threshold value of

  3. Combining Expressed Vocational Choice and Measures of Career Development to Predict Future Occupational Field.

    ERIC Educational Resources Information Center

    Noeth, Richard J.

    A study was designed to test predictability of actual occupation from expressed vocational choice when combined separately with measures of career development. Subjects were 1,994 members of a national study of high school career development who were working more than half-time three years later (1976). Expressed vocational choice and measures of…

  4. Evaluation of different field methods for measuring soil water infiltration

    NASA Astrophysics Data System (ADS)

    Pla-Sentís, Ildefonso; Fonseca, Francisco

    2010-05-01

    Soil infiltrability, together with rainfall characteristics, is the most important hydrological parameter for the evaluation and diagnosis of the soil water balance and soil moisture regime. Those balances and regimes are the main regulating factors of the on site water supply to plants and other soil organisms and of other important processes like runoff, surface and mass erosion, drainage, etc, affecting sedimentation, flooding, soil and water pollution, water supply for different purposes (population, agriculture, industries, hydroelectricity), etc. Therefore the direct measurement of water infiltration rates or its indirect deduction from other soil characteristics or properties has become indispensable for the evaluation and modelling of the previously mentioned processes. Indirect deductions from other soil characteristics measured under laboratory conditions in the same soils, or in other soils, through the so called "pedo-transfer" functions, have demonstrated to be of limited value in most of the cases. Direct "in situ" field evaluations have to be preferred in any case. In this contribution we present the results of past experiences in the measurement of soil water infiltration rates in many different soils and land conditions, and their use for deducing soil water balances under variable climates. There are also presented and discussed recent results obtained in comparing different methods, using double and single ring infiltrometers, rainfall simulators, and disc permeameters, of different sizes, in soils with very contrasting surface and profile characteristics and conditions, including stony soils and very sloping lands. It is concluded that there are not methods universally applicable to any soil and land condition, and that in many cases the results are significantly influenced by the way we use a particular method or instrument, and by the alterations in the soil conditions by the land management, but also due to the manipulation of the surface

  5. Predicted Effect of Geomagnetic Field on CALET Measurements

    NASA Astrophysics Data System (ADS)

    Rauch, Brian

    2014-03-01

    The CALorimetric Electron Telescope (CALET), comprised of the main calorimeter (CAL) and Gamma-ray Burst Monitor (CGBM) subsystem, is under construction for launch to the ISS. CAL consists of a scintillator Charge Detector (CHD), a 3 radiation length (X0) deep scintillating fiber Imaging Calorimeter (IMC), and a 27 X0 deep PWO Total Absorption Calorimeter (TASC). The primary objectives of CAL are to measure energy spectra of electrons from 1GeV to 20 TeV and nuclei through iron up to 1,000 TeV, and to detect gamma-rays above 10 GeV. Earth's geomagnetic field in the 51.6° inclination ISS orbit will affect the observed fluxes of charged particles. Rigidity cutoffs based on geomagnetic latitude and East-West angle will introduce structure to the charged particle energy spectra. They can also be exploited to facilitate the measurement of distinct positron and electron fluxes between ~3-20 GeV, and the relative abundances of the rare ultra-heavy (UH) nuclei (30 <= Z <= 40) by using the cutoffs to select nuclei near and above the CHD minimum ionization threshold so that they can be identified using the CHD and top IMC layers without requiring energy determination in the TASC. In 5-years CAL would collect ~2 × the UH statistics of TIGER. This research was supported by NASA at Washington University under Grant Number NNX11AE02G.

  6. A measurement system applicable for landslide experiments in the field.

    PubMed

    Guo, Wen-Zhao; Xu, Xiang-Zhou; Wang, Wen-Long; Yang, Ji-Shan; Liu, Ya-Kun; Xu, Fei-Long

    2016-04-01

    Observation of gravity erosion in the field with strong sunshine and wind poses a challenge. Here, a novel topography meter together with a movable tent addresses the challenge. With the topography meter, a 3D geometric shape of the target surface can be digitally reconstructed. Before the commencement of a test, the laser generator position and the camera sightline should be adjusted with a sight calibrator. Typically, the topography meter can measure the gravity erosion on the slope with a gradient of 30°-70°. Two methods can be used to obtain a relatively clear video, despite the extreme steepness of the slopes. One method is to rotate the laser source away from the slope to ensure that the camera sightline remains perpendicular to the laser plane. Another way is to move the camera farther away from the slope in which the measured volume of the slope needs to be corrected; this method will reduce distortion of the image. In addition, installation of tent poles with concrete columns helps to surmount the altitude difference on steep slopes. Results observed by the topography meter in real landslide experiments are rational and reliable. PMID:27131688

  7. A measurement system applicable for landslide experiments in the field

    NASA Astrophysics Data System (ADS)

    Guo, Wen-Zhao; Xu, Xiang-Zhou; Wang, Wen-Long; Yang, Ji-Shan; Liu, Ya-Kun; Xu, Fei-Long

    2016-04-01

    Observation of gravity erosion in the field with strong sunshine and wind poses a challenge. Here, a novel topography meter together with a movable tent addresses the challenge. With the topography meter, a 3D geometric shape of the target surface can be digitally reconstructed. Before the commencement of a test, the laser generator position and the camera sightline should be adjusted with a sight calibrator. Typically, the topography meter can measure the gravity erosion on the slope with a gradient of 30°-70°. Two methods can be used to obtain a relatively clear video, despite the extreme steepness of the slopes. One method is to rotate the laser source away from the slope to ensure that the camera sightline remains perpendicular to the laser plane. Another way is to move the camera farther away from the slope in which the measured volume of the slope needs to be corrected; this method will reduce distortion of the image. In addition, installation of tent poles with concrete columns helps to surmount the altitude difference on steep slopes. Results observed by the topography meter in real landslide experiments are rational and reliable.

  8. Measurement of neutron and gamma radiation in a mixed field.

    PubMed

    Kronenberg, S; Bechtel, E; Brucker, G J

    1995-10-01

    This paper describes a study of dosimeters with a range of 0 to 0.2 mGy that were developed by the authors and built by the Federal Emergency Management Agency (FEMA). These instruments are a type of air-filled ion chamber that is self-reading by means of an internal carbon fiber electrometer. Two types of these dosimeters were constructed: one with an ion chamber wall made of a conductive hydrogenous material, and the other device made with a conductive wall lining of non-hydrogenous material. Both types of dosimeters have the same sensitivity for gamma radiation, but greatly different sensitivities for fast neutrons, thus making it possible to measure gamma radiation and neutron doses separately in a mixed radiation field. The results indicate that such pairs of dosimeters can be used for the first time to accurately monitor personnel for gamma ray and neutron doses in real time. Since the difference in neutron sensitivities is due to the properties of wall materials, periodic calibrations of the dosimeter system can be accomplished using only gamma rays after the material constants are measured. The absolute number of neutron induced transmutations in sulfur was required for this work. Methods and techniques which were applied to determine this quantity are described in the text. This approach was one of several dosimetric procedures utilized in this investigation. PMID:7558835

  9. Electric Field Change Measurements of a Terrestrial Gamma Ray Flash

    NASA Astrophysics Data System (ADS)

    Marshall, Thomas; Karunarathne, Sumedhe; Stolzenburg, Maribeth

    2016-04-01

    Cummer et al. [GRL, 2014] reported on two terrestrial gamma ray flashes (TGFs) detected by the Gamma ray Burst Monitor (GBM) on the Fermi satellite. At a range of 632 km we detected an electric field change pulse associated with the first of these TGFs. The sensor bandwidth was 0.16 Hz - 2.6 MHz and was sampled at 5 MS/s. The measured zero-to-peak amplitude was 3.1 V/m. Assuming a 1/R range dependence, the amplitude range normalized to 100 km would be about 20 V/m. However, a little more than half of the path from the TGF to the sensor was over land rather than ocean, which should cause the attenuation to be greater than 1/R. Based on recent measurements of Kolmasova et al. (2015 AGU Fall Meeting), we estimate that the real peak amplitude was 40 - 50 V/m. The detected pulse was bipolar with a leading positive peak and had an overall duration of about 50 μs; these characteristics are typical of initial breakdown pulses (IBPs) that occur at the beginning of intracloud (IC) flashes. However, the pulse amplitude is an order of magnitude larger than typical IBPs. These data support the notion that IBPs of IC flashes cause TGFs [e.g., Shao et al., JGR 2010; Lu et al., GRL 2010; Cummer et al., GRL 2014].

  10. Biases in field measurements of ice nuclei concentrations

    NASA Astrophysics Data System (ADS)

    Garimella, S.; Voigtländer, J.; Kulkarni, G.; Stratmann, F.; Cziczo, D. J.

    2015-12-01

    Ice nuclei (IN) play an important role in the climate system by influencing cloud properties, precipitation, and radiative transfer. Despite their importance, there are significant uncertainties in estimating IN concentrations because of the complexities of atmospheric ice nucleation processes. Field measurements of IN concentrations with Continuous Flow Diffusion Chamber (CFDC) IN counters have been vital to constrain IN number concentrations and have led to various parameterizations of IN number vs. temperature and particle concentration. These parameterizations are used in many global climate models, which are very sensitive to the treatment of cloud microphysics. However, due to non-idealities in CFDC behavior, especially at high relative humidity, many of these measurements are likely biased too low. In this study, the extent of this low bias is examined with laboratory experiments at a variety of instrument conditions using the SPectrometer for Ice Nucleation, a commercially-available CFDC-style chamber. These laboratory results are compared to theoretical calculations and computational fluid dynamics models to map the variability of this bias as a function of chamber temperature and relative humidity.

  11. Neutron field measurements at the Aladdin Synchrotron Light Source.

    PubMed

    Yang, Y; Li, Y; DeLuca, P M; Otte, R; Rowe, E M

    1986-01-01

    The neutron field near the inflector of the 800-MeV electron storage ring was studied. Photon-induced neutrons are produced by 100-MeV electrons bombarding the inflector during injection into the synchrotron ring. Neutrons were measured with moderating detectors made of 15 X 15 X 20 cm Lucite blocks and Au activation foils. Detector response was established with a Pu-Be neutron source and a 25.4-cm polyethylene sphere and Au foil detector. The neutron yield was 0.97 +/- 0.14 X 10(12) kJ-1. For 1.38 W of electron pulse power, the dose equivalent rate 1 m aside and 1 m above the inflector was 4.35 +/- 0.47 mu Sv s-1 and 3.13 +/- 0.23 mu Sv s-1, respectively. A measured dose equivalent transmission curve for polyethylene yielded an attenuation coefficient of 15.7 m-1. PMID:3943962

  12. Lead field theoretical approach in bioimpedance measurements: towards more controlled measurement sensitivity.

    PubMed

    Kauppinen, P K; Hyttinen, J A; Kööbi, T; Malmivuo, J

    1999-04-20

    This study was conducted to demonstrate the potentiality of lead field theoretical approach in analyzing bioimpedance (BI) measurements. Anatomically accurate computer models and the lead field theory were used to develop BI measurement configurations capable of detecting more localized BI changes in the human body. The methods were applied to assess the measurement properties of conventional impedance cardiography (ICG) and such BI measurement configurations as can be derived using (i) the 12-lead electrocardiography (ECG) and (ii) the international 10-20 electroencephalography (EEG) electrode systems. Information as to how various electrode configurations are sensitive to detecting conductivity changes in different tissues and organs was thus obtained. Theoretical results with the 12-lead system suggested that, compared to conventional ICGs, significantly more selective ICG configurations can be derived for cardiovascular structures. In addition to theoretical investigations, clinical test measurements were made with the 12-lead system to establish whether characteristic waveforms are available. Sensitivity distributions obtained with the 10-20 electrode system give promise of the possibility of monitoring noninvasively cerebrospinal fluid (CSF) impedance changes related to impending epileptic seizures. PMID:10372161

  13. Three-dimensional measurement of the laminar flow field inside a static mixer

    NASA Astrophysics Data System (ADS)

    Speetjens, Michel; Jilisen, Rene; Bloemen, Paul

    2011-11-01

    Static mixers are widely used in industry for laminar mixing of viscous fluids as e.g. polymers and food stuffs. Moreover, given the similarities in flow regime, static mixers often serve as model for compact mixers for process intensification and even for micro-mixers. This practical relevance has motivated a host of studies on the mixing characteristics of static mixers and their small-scale counterparts. However, these studies are primarily theoretical and numerical. Experimental studies, in contrast, are relatively rare and typically restricted to local 2D flow characteristics or integral quantities (pressure drop, residence-time distributions). The current study concerns 3D measurements on the laminar flow field inside a static mixer using 3D Particle-Tracking Velocimetry (3D-PTV) Key challenges to the 3D-PTV image-processing procedure are the optical distortion and degradation of the particle imagery due to light refraction and reflection caused by the cylindrical boundary and the internal elements. Ways to tackle these challenges are discussed and first successful 3D measurements in an actual industrial static mixer are presented.

  14. Results from laboratory and field testing of nitrate measuring spectrophotometers

    USGS Publications Warehouse

    Snazelle, Teri T.

    2015-01-01

    In Phase II, the analyzers were deployed in field conditions at three diferent USGS sites. The measured nitrate concentrations were compared to discrete (reference) samples analyzed by the Direct UV method on a Shimadzu UV1800 bench top spectrophotometer, and by the National Environmental Methods Index (NEMI) method I-2548-11 at the USGS National Water Quality Laboratory. The first deployment at USGS site 0249620 on the East Pearl River in Hancock County, Mississippi, tested the ability of the TriOs ProPs (10-mm path length), Hach NITRATAX (5 mm), Satlantic SUNA (10 mm), and the S::CAN Spectro::lyser (5 mm) to accurately measure low-level (less than 2 mg-N/L) nitrate concentrations while observing the effect turbidity and colored dissolved organic matter (CDOM) would have on the analyzers' measurements. The second deployment at USGS site 01389005 Passaic River below Pompton River at Two Bridges, New Jersey, tested the analyzer's accuracy in mid-level (2-8 mg-N/L) nitrate concentrations. This site provided the means to test the analyzers' performance in two distinct matrices—the Passaic and the Pompton Rivers. In this deployment, three instruments tested in Phase I (TriOS, Hach, and SUNA) were deployed with the S::CAN Spectro::lyser (35 mm) already placed by the New Jersey Water Science Center (WSC). The third deployment at USGS site 05579610 Kickapoo Creek at 2100E Road near Bloomington, Illinois, tested the ability of the analyzers to measure high nitrate concentrations (greater than 8 mg-N/L) in turbid waters. For Kickapoo Creek, the HIF provided the TriOS (10 mm) and S::CAN (5 mm) from Phase I, and a SUNA V2 (5 mm) to be deployed adjacent to the Illinois WSC-owned Hach (2 mm). A total of 40 discrete samples were collected from the three deployment sites and analyzed. The nitrate concentration of the samples ranged from 0.3–22.2 mg-N/L. The average absolute difference between the TriOS measurements and discrete samples was 0.46 mg-N/L. For the combined data

  15. Field measurement of basal forces generated by erosive debris flows

    USGS Publications Warehouse

    McCoy, S.W.; Tucker, G.E.; Kean, J.W.; Coe, J.A.

    2013-01-01

    It has been proposed that debris flows cut bedrock valleys in steeplands worldwide, but field measurements needed to constrain mechanistic models of this process remain sparse due to the difficulty of instrumenting natural flows. Here we present and analyze measurements made using an automated sensor network, erosion bolts, and a 15.24 cm by 15.24 cm force plate installed in the bedrock channel floor of a steep catchment. These measurements allow us to quantify the distribution of basal forces from natural debris‒flow events that incised bedrock. Over the 4 year monitoring period, 11 debris‒flow events scoured the bedrock channel floor. No clear water flows were observed. Measurements of erosion bolts at the beginning and end of the study indicated that the bedrock channel floor was lowered by 36 to 64 mm. The basal force during these erosive debris‒flow events had a large‒magnitude (up to 21 kN, which was approximately 50 times larger than the concurrent time‒averaged mean force), high‒frequency (greater than 1 Hz) fluctuating component. We interpret these fluctuations as flow particles impacting the bed. The resulting variability in force magnitude increased linearly with the time‒averaged mean basal force. Probability density functions of basal normal forces were consistent with a generalized Pareto distribution, rather than the exponential distribution that is commonly found in experimental and simulated monodispersed granular flows and which has a lower probability of large forces. When the bed sediment thickness covering the force plate was greater than ~ 20 times the median bed sediment grain size, no significant fluctuations about the time‒averaged mean force were measured, indicating that a thin layer of sediment (~ 5 cm in the monitored cases) can effectively shield the subjacent bed from erosive impacts. Coarse‒grained granular surges and water‒rich, intersurge flow had very similar basal force distributions despite

  16. Validation of two energy balance closure parameterisations using field measurements

    NASA Astrophysics Data System (ADS)

    Eder, Fabian; De Roo, Frederik; Kohnert, Katrin; Desjardins, Raymond L.; Foken, Thomas; Schmid, Hans Peter; Mauder, Matthias

    2013-04-01

    Eddy Covariance (EC) measurements often do not close the energy balance. This indicates that surface heat fluxes are underestimated, likely because large-scale eddies and stationary circulations are not captured. Because EC is a widespread tool in environmental science to assess energy fluxes and trace gas budgets, it is essential to quantify the 'missing' fluxes. In the literature, two approaches to parameterise the lack of energy balance closure can be found. The first one by Huang et al (2008) is based on large-eddy simulations (LES) and perceives the energy imbalance as being the result of large-scale turbulent organized structures. The second approach by Panin and Bernhofer (2008) suggests an empirical approach which focuses on surface roughness heterogeneities on the landscape-scale. We tested both approaches with EC data from three sites, located in southern Germany, of the Terrestrial Environmental Observatories (TERENO) programme. Additionally, we applied the parameterisations to aircraft data from Canada, which were conducted as part of the Boreal Ecosystem-Atmosphere Study (BOREAS) experiment and the Boreal Ecosystem Research and Monitoring Sites (BERMS) programme. For each flight, the flux contribution of turbulent structures larger than 2 km, determined by wavelet analysis, serves as an estimate of the missing flux of conventional EC measurements. In most cases, the two parameterisations do not give a reliable prediction of the energy balance residual. The approach of Panin and Bernhofer (2008) disregards topographical effects, differences in surface moisture and surface temperature and thus, it cannot explain the poor energy balance closure of the TERENO sites. However, above the flat terrain of the airborne measurements in Canada, it works surprisingly well. The parameterisation by Huang et al (2008) was developed for homogeneous terrain, a condition which is almost never met in field studies. In addition, there is a general mismatch between LES and

  17. The actual goals of geoethics

    NASA Astrophysics Data System (ADS)

    Nemec, Vaclav

    2014-05-01

    The most actual goals of geoethics have been formulated as results of the International Conference on Geoethics (October 2013) held at the geoethics birth-place Pribram (Czech Republic): In the sphere of education and public enlightenment an appropriate needed minimum know how of Earth sciences should be intensively promoted together with cultivating ethical way of thinking and acting for the sustainable well-being of the society. The actual activities of the Intergovernmental Panel of Climate Changes are not sustainable with the existing knowledge of the Earth sciences (as presented in the results of the 33rd and 34th International Geological Congresses). This knowledge should be incorporated into any further work of the IPCC. In the sphere of legislation in a large international co-operation following steps are needed: - to re-formulate the term of a "false alarm" and its legal consequences, - to demand very consequently the needed evaluation of existing risks, - to solve problems of rights of individuals and minorities in cases of the optimum use of mineral resources and of the optimum protection of the local population against emergency dangers and disasters; common good (well-being) must be considered as the priority when solving ethical dilemmas. The precaution principle should be applied in any decision making process. Earth scientists presenting their expert opinions are not exempted from civil, administrative or even criminal liabilities. Details must be established by national law and jurisprudence. The well known case of the L'Aquila earthquake (2009) should serve as a serious warning because of the proven misuse of geoethics for protecting top Italian seismologists responsible and sentenced for their inadequate superficial behaviour causing lot of human victims. Another recent scandal with the Himalayan fossil fraud will be also documented. A support is needed for any effort to analyze and to disclose the problems of the deformation of the contemporary

  18. Forecasting auroras from regional and global magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Kauristie, Kirsti; Myllys, Minna; Partamies, Noora; Viljanen, Ari; Peitso, Pyry; Juusola, Liisa; Ahmadzai, Shabana; Singh, Vikramjit; Keil, Ralf; Martinez, Unai; Luginin, Alexej; Glover, Alexi; Navarro, Vicente; Raita, Tero

    2016-06-01

    We use the connection between auroral sightings and rapid geomagnetic field variations in a concept for a Regional Auroral Forecast (RAF) service. The service is based on statistical relationships between near-real-time alerts issued by the NOAA Space Weather Prediction Center and magnetic time derivative (dB/dt) values measured by five MIRACLE magnetometer stations located in Finland at auroral and sub-auroral latitudes. Our database contains NOAA alerts and dB/dt observations from the years 2002-2012. These data are used to create a set of conditional probabilities, which tell the service user when the probability of seeing auroras exceeds the average conditions in Fennoscandia during the coming 0-12 h. Favourable conditions for auroral displays are associated with ground magnetic field time derivative values (dB/dt) exceeding certain latitude-dependent threshold values. Our statistical analyses reveal that the probabilities of recording dB/dt exceeding the thresholds stay below 50 % after NOAA alerts on X-ray bursts or on energetic particle flux enhancements. Therefore, those alerts are not very useful for auroral forecasts if we want to keep the number of false alarms low. However, NOAA alerts on global geomagnetic storms (characterized with Kp values > 4) enable probability estimates of > 50 % with lead times of 3-12 h. RAF forecasts thus rely heavily on the well-known fact that bright auroras appear during geomagnetic storms. The additional new piece of information which RAF brings to the previous picture is the knowledge on typical storm durations at different latitudes. For example, the service users south of the Arctic Circle will learn that after a NOAA ALTK06 issuance in night, auroral spotting should be done within 12 h after the alert, while at higher latitudes conditions can remain favourable during the next night.

  19. Actualities and Perspectives in Neurosurgery

    PubMed Central

    Iencean, SM; Brehar, FM

    2008-01-01

    In the field of neurosurgery, like in other surgical specialties, the last decades have brought major achievements. The series of revolutionary discoveries has started during the last century in the fifties, with stereotactic radiosurgery, then continued with the implementation of operative microscope (during the seventies), the endovascular embolisation in the nineties and finally with the major improvement in robotic neurosurgery and molecular neurosurgery at the beginning of this century. The major innovation has been brought not only in the field of therapeutical measures but also in the field of neuro– imaging. Thus, the modern MRI with more than 3 Tesla, can reveal to the neurosurgeon the most intimate structures of the nervous system. Several important areas in neurosurgery like: vascular neurosurgery, functional neurosurgery and brain tumors pathology, benefit from the modern technology and from the latest discoveries from genetic and molecular biology. In conclusion, summarizing the discoveries of the last decade, we emphasize that the related areas like genetics, molecular biology, computer technology become more and more important in the future progress of the neurosurgery. PMID:20108475

  20. Wake Vortex Field Measurement Program at Memphis, Tennessee: Data Guide

    NASA Technical Reports Server (NTRS)

    Campbell, S. D.; Dasey, T. J.; Freehart, R. E.; Heinrichs, R. M.; Mathews, M. P.; Perras, G. H.; Rowe, G. S.

    1997-01-01

    Eliminating or reducing current restrictions in the air traffic control system due to wake vortex considerations would yield increased capacity, decreased delays, and cost savings. Current wake vortex separation standards are widely viewed as very conservative under most conditions. However, scientific uncertainty about wake vortex behavior under different atmospheric conditions remains a barrier to development of an adaptive vortex spacing system. The objective of the wake vortex field measurement efforts during December, 1994 and August, 1995 at Memphis, TN were to record wake vortex behavior for varying atmospheric conditions and types of aircraft. This effort is part of a larger effort by the NASA Langley Research Center to develop an Aircraft Vortex Spacing System (AVOSS) as an element of the Terminal Area Productivity (TAP) program. The TAP program is being performed in concert with the FAA Terminal Air Traffic Control Automation (TATCA) program and ATC Automation. Wake vortex behavior was observed using a mobile continuous-wave (CW) coherent laser Doppler radar (lidar) developed at Lincoln Laboratory. This lidar features a number of improvements over previous systems, including the first-ever demonstration of an automatic wake vortex detection and tracking algorithm.

  1. Direct measurement of the upper critical field in cuprate superconductors

    NASA Astrophysics Data System (ADS)

    Grissonnanche, G.; Cyr-Choinière, O.; Laliberté, F.; René de Cotret, S.; Juneau-Fecteau, A.; Dufour-Beauséjour, S.; Delage, M.-È.; Leboeuf, D.; Chang, J.; Ramshaw, B. J.; Bonn, D. A.; Hardy, W. N.; Liang, R.; Adachi, S.; Hussey, N. E.; Vignolle, B.; Proust, C.; Sutherland, M.; Krämer, S.; Park, J.-H.; Graf, D.; Doiron-Leyraud, N.; Taillefer, Louis

    2014-02-01

    In the quest to increase the critical temperature Tc of cuprate superconductors, it is essential to identify the factors that limit the strength of superconductivity. The upper critical field Hc2 is a fundamental measure of that strength, yet there is no agreement on its magnitude and doping dependence in cuprate superconductors. Here we show that the thermal conductivity can be used to directly detect Hc2 in the cuprates YBa2Cu3Oy, YBa2Cu4O8 and Tl2Ba2CuO6+δ, allowing us to map out Hc2 across the doping phase diagram. It exhibits two peaks, each located at a critical point where the Fermi surface of YBa2Cu3Oy is known to undergo a transformation. Below the higher critical point, the condensation energy, obtained directly from Hc2, suffers a sudden 20-fold collapse. This reveals that phase competition—associated with Fermi-surface reconstruction and charge-density-wave order—is a key limiting factor in the superconductivity of cuprates.

  2. An evaluation of RAMS radiation schemes by field measurements

    SciTech Connect

    Zhong, S; Doran, J C

    1994-02-01

    At present, two radiation schemes are used in RAMS: the Mahrer and Pielke (M-P) scheme and the Chen and Cotton (C-C) scheme. The M-P scheme requires little computational expense, but does not include the radiative effects of liquid water or ice; the C-C scheme accounts for the radiative effects of liquid water and ice but is fairly expensive computationally. For simulations with clouds, the C-C scheme is obviously a better choice, but for clear sky conditions, RAMS users face a decision regarding which radiation scheme to use. It has been noted that the choice of radiation scheme may result in significantly different results for the same case. To examine the differences in the radiative fluxes and the boundary-layer structure corresponding to the two radiation schemes in RAMS we have carried out a study where Rams was used to simulate the same case with two different radiation schemes. The modeled radiative fluxes by the two schemes were then compared with the field measurements. A description of the observations and the case study, a comparison and discussion of the results, and a summary and conclusions follow.

  3. Direct measurement of the upper critical field in cuprate superconductors

    PubMed Central

    Grissonnanche, G.; Cyr-Choinière, O.; Laliberté, F.; René de Cotret, S.; Juneau-Fecteau, A.; Dufour-Beauséjour, S.; Delage, M. -È.; LeBoeuf, D.; Chang, J.; Ramshaw, B. J.; Bonn, D. A.; Hardy, W. N.; Liang, R.; Adachi, S.; Hussey, N. E.; Vignolle, B.; Proust, C.; Sutherland, M.; Krämer, S.; Park, J. -H.; Graf, D.; Doiron-Leyraud, N.; Taillefer, Louis

    2014-01-01

    In the quest to increase the critical temperature Tc of cuprate superconductors, it is essential to identify the factors that limit the strength of superconductivity. The upper critical field Hc2 is a fundamental measure of that strength, yet there is no agreement on its magnitude and doping dependence in cuprate superconductors. Here we show that the thermal conductivity can be used to directly detect Hc2 in the cuprates YBa2Cu3Oy, YBa2Cu4O8 and Tl2Ba2CuO6+δ, allowing us to map out Hc2 across the doping phase diagram. It exhibits two peaks, each located at a critical point where the Fermi surface of YBa2Cu3Oy is known to undergo a transformation. Below the higher critical point, the condensation energy, obtained directly from Hc2, suffers a sudden 20-fold collapse. This reveals that phase competition—associated with Fermi-surface reconstruction and charge-density-wave order—is a key limiting factor in the superconductivity of cuprates. PMID:24518054

  4. Measurements of the Lunar Gravity Field using a Relay Subsatellite

    NASA Astrophysics Data System (ADS)

    Namiki, Noriyuki; Hanada, H.; Kawano, N.; Heki, K.; Iwata, T.; Ogawa, M.; Takano, T.

    1998-01-01

    Estimating spherical harmonic coefficients of the lunar gravity field has been a focus in selenodesy since the late 1960s when Doppler tracking data from lunar orbiters were first analyzed. Early analyses were limited by the low degree and order of the spherical harmonic solutions, mostly due to the slow speed and low memory of the then-available computers. However, rapid development of the computational ability has increased the resolution of the lunar gravity models significantly. Doppler tracking data from lunar orbiters 1-5 and Apollo subsatellites up to degree and order 60 (Lun60d) have been analyzed. Further, the tracking data from the Clementine spacecraft launched in 1994 has been incorporated, and a model complete to degree and order 70 (GLGM-2) has been developed. These high-resolution gravity models have been used for studies of internal structure and tectonics of the Moon. Interestingly, Lun60d and GLGM-2 show significant differences in the spherical harmonic coefficients for degree greater than 20. Because the semimajor axis of Clementine's orbit is nearly twice as large as the radius of the Moon, the contribution of the new tracking data is prevailed in the low-degree field. Methodologically, the differences in the high-degree field arise from the different weighting of the tracking data and gravity model, but, in principle, these are caused by a lack of tracking data over the farside. While the current Lunar Prospector mission is expected to improve the spatial resolution over the mid- to high-latitude regions of the nearside significantly, the absence of Doppler tracking data over the farside remains unresolved. To complete the coverage of tracking over the farside, we are developing a satellite-to-satellite (four-way) Doppler tracking experiment in SELENE (the SELenological and ENgineering Explorer) project of Japan. Outline of the Mission: The SELENE is a joint project by the National Space Development Agency of Japan (NASDA) and the Institute of

  5. Simultaneous electric-field measurements on nearby balloons.

    NASA Technical Reports Server (NTRS)

    Mozer, F. S.

    1972-01-01

    Electric-field payloads were flown simultaneously on two balloons from Great Whale River, Canada, on September 21, 1971, to provide data at two points in the upper atmosphere that differed in altitude by more than one atmospheric density scale height and in horizontal position by 30-140 km. The altitude dependences in the two sets of data prove conclusively that the vertical electric field at balloon altitudes stems from fair-weather atmospheric electricity sources and that the horizontal fields are mapped down ionospheric fields, since the weather-associated horizontal fields were smaller than 2 mV/m.

  6. Magnetic-field sensing coil embedded in ceramic for measuring ambient magnetic field

    DOEpatents

    Takahashi, Hironori

    2004-02-10

    A magnetic pick-up coil for measuring magnetic field with high specific sensitivity, optionally with an electrostatic shield (24), having coupling elements (22) with high winding packing ratio, oriented in multiple directions, and embedded in ceramic material for structural support and electrical insulation. Elements of the coil are constructed from green ceramic sheets (200) and metallic ink deposited on surfaces and in via holes of the ceramic sheets. The ceramic sheets and the metallic ink are co-fired to create a monolithic hard ceramic body (20) with metallized traces embedded in, and placed on exterior surfaces of, the hard ceramic body. The compact and rugged coil can be used in a variety of environments, including hostile conditions involving ultra-high vacuum, high temperatures, nuclear and optical radiation, chemical reactions, and physically demanding surroundings, occurring either individually or in combinations.

  7. A poloidal field measurement technique: Pitch angle measurements via injected He/sup +/ ions

    SciTech Connect

    Jobes, F.C.

    1989-07-01

    The poloidal field of a tokamak can be determined by observing the light emitted by He/sup +/ ions injected into the plasma by a perpendicular He/sup 0/ beam. These ions will orbit in small circles located where the neutral atom became ionized, and they will remain there for a few microseconds. During this time, some of these ions will also emit light at various spectral lines. The observed spectrum of any of these lines will have a peculiar and very wide shape, and it will be offset (Doppler shifted) with respect to the natural line location. The location and width of the spectral pattern provide independent information about the components of the poloidal field which are parallel and perpendicular to the beam velocity, and this information is local to the point where the light is emitted. For a horizontal beam, these components are b/sub x/ and b/sub y/, respectively. The difference in Doppler shift between two measurement points above one another (at the top and bottom of the beam) is directly proportional to /delta/b/sub x/, which in turn is proportional to the transform on that flux surface. Thus, this technique provides a means to measure directly local values of q(r). Simulation studies indicate that accurate measurements can be made in milliseconds. 6 refs., 8 figs.

  8. Comparing historical and modern methods of Sea Surface Temperature measurement - Part 1: Review of methods, field comparisons and dataset adjustments

    NASA Astrophysics Data System (ADS)

    Matthews, J. B. R.

    2012-09-01

    Sea Surface Temperature (SST) measurements have been obtained from a variety of different platforms, instruments and depths over the post-industrial period. Today most measurements come from ships, moored and drifting buoys and satellites. Shipboard methods include temperature measurement of seawater sampled by bucket and in engine cooling water intakes. Engine intake temperatures are generally thought to average a few tenths of a °C warmer than simultaneous bucket temperatures. Here I review SST measurement methods, studies comparing shipboard methods by field experiment and adjustments applied to SST datasets to account for variable methods. In opposition to contemporary thinking, I find average bucket-intake temperature differences reported from field studies inconclusive. Non-zero average differences often have associated standard deviations that are several times larger than the averages themselves. Further, average differences have been found to vary widely between ships and between cruises on the same ship. The cause of non-zero average differences is typically unclear given the general absence of additional temperature observations to those from buckets and engine intakes. Shipboard measurements appear of variable quality, highly dependent upon the accuracy and precision of the thermometer used and the care of the observer where manually read. Methods are generally poorly documented, with written instructions not necessarily reflecting actual practices of merchant mariners. Measurements cannot be expected to be of high quality where obtained by untrained sailors using thermometers of low accuracy and precision.

  9. Pattern recognition techniques and the measurement of solar magnetic fields

    NASA Astrophysics Data System (ADS)

    Lopez Ariste, Arturo; Rees, David E.; Socas-Navarro, Hector; Lites, Bruce W.

    2001-11-01

    Measuring vector magnetic fields in the solar atmosphere using the profiles of the Stokes parameters of polarized spectral lines split by the Zeeman effect is known as Stokes Inversion. This inverse problem is usually solved by least-squares fitting of the Stokes profiles. However least-squares inversion is too slow for the new generation of solar instruments (THEMIS, SOLIS, Solar-B, ...) which will produce an ever-growing flood of spectral data. The solar community urgently requires a new approach capable of handling this information explosion, preferably in real-time. We have successfully applied pattern recognition and machine learning techniques to tackle this problem. For example, we have developed PCA-inversion, a database search technique based on Principal Component Analysis of the Stokes profiles. Search is fast because it is carried out in low dimensional PCA feature space, rather than the high dimensional space of the spectral signals. Such a data compression approach has been widely used for search and retrieval in many areas of data mining. PCA-inversion is the basis of a new inversion code called FATIMA (Fast Analysis Technique for the Inversion of Magnetic Atmospheres). Tests on data from HAO's Advanced Stokes Polarimeter show that FATIMA isover two orders of magnitude faster than least squares inversion. Initial tests on an alternative code (DIANNE - Direct Inversion based on Artificial Neural NEtworks) show great promise of achieving real-time performance. In this paper we present the latest achievements of FATIMA and DIANNE, two powerful examples of how pattern recognition techniques can revolutionize data analysis in astronomy.

  10. Field measurements of tracer gas transport by barometric pumping

    SciTech Connect

    Lagus, P.L.; McKinnis, W.B.; Hearst, J.R.; Burkhard, N.R.; Smith, C.F.

    1994-07-28

    Vertical gas motions induced by barometric pressure variations can carry radioactive gases out of the rubblized region produced by an underground nuclear explosion, through overburden rock, into the atmosphere. To better quantify transit time and amount of transport, field experiments were conducted at two sites on Pahute Mesa, Kapelli and Tierra, where radioactive gases had been earlier detected in surface cracks. At each site, two tracer gases were injected into the rubblized chimney 300-400 m beneath the surface and their arrival was monitored by concentration measurements in gas samples extracted from shallow collection holes. The first ``active`` tracer was driven by a large quantity of injected air; the second ``passive`` tracer was introduced with minimal gas drive to observe the natural transport by barometric pumping. Kapelli was injected in the fall of 1990, followed by Tierra in the fall of 1991. Data was collected at both sites through the summer of 1993. At both sites, no surface arrival of tracer was observed during the active phase of the experiment despite the injection of several million cubic feet of air, suggesting that cavity pressurization is likely to induce horizontal transport along high permeability layers rather than vertical transport to the surface. In contrast, the vertical pressure gradients associated with barometric pumping brought both tracers to the surface in comparable concentrations within three months at Kapelli, whereas 15 months elapsed before surface arrival at Tierra. At Kapelli, a quasisteady pumping regime was established, with tracer concentrations in effluent gases 1000 times smaller than concentrations thought to exist in the chimney. Tracer concentrations observed at Tierra were typically an order of magnitude smaller. Comparisons with theoretical calculations suggest that the gases are traveling through {approximately}1 millimeter vertical fractures spaced 2 to 4 meters apart. 6 refs., 18 figs., 3 tabs.

  11. Linguistic Theory and Actual Language.

    ERIC Educational Resources Information Center

    Segerdahl, Par

    1995-01-01

    Examines Noam Chomsky's (1957) discussion of "grammaticalness" and the role of linguistics in the "correct" way of speaking and writing. It is argued that the concern of linguistics with the tools of grammar has resulted in confusion, with the tools becoming mixed up with the actual language, thereby becoming the central element in a metaphysical…

  12. Measurements of magnetic fields in different types of stars

    NASA Astrophysics Data System (ADS)

    Darlington Landstreet, John

    2015-08-01

    The recent generation of highly efficient broadband spectropolarimeters (both low and high-resolution instruments) such as MuSiCoS (TBL), FORS (ESO-Paranal), UAGS and MSS (SAO), ESPaDOnS (CFHT), NARVAL (TBL), and HARPSpol (ESO-La Silla) have revolutionised the detection and study of stellar magnetic fields.With these instruments magnetic fields have been detected in most of the major stages of stellar evolution. Dynamo field (apparently generated by the action of a current dynamo, as in the Sun) are found in T Tau stars, rapidly rotating lower main sequence stars (both single stars and close binaries), red giants, and AGB stars. Fossil fields (fields retained from an earlier stage of evolution) are found in a few pre-main sequence Herbig AeBe stars, in roughly 10% of all A, B and O main sequence stars, and in white dwarfs and neutron stars.From these results a global view of the occurence of magnetism in stars is beginning to emerge. Furthermore, we are understanding better the role of magnetic fields in transport of angular momentum within and around stars, the effects of fields on transport of chemical elements, and the ways in which fields are related to surface activity and winds. However, understanding of how fields arise in stars, how they evolve as the underlying stars evolve, and how they affect stellar evolution, is still very incomplete.This talk will survey very broadly the emerging view of stellar magnetism.

  13. A comparison of satellite systems for gravity field measurements

    NASA Technical Reports Server (NTRS)

    Argentiero, P. D.; Lowrey, B. E.

    1977-01-01

    A detailed and accurate earth gravity field model is important to the understanding of the structure and composition of the earth's crust and upper mantle. Various satellite-based techniques for providing more accurate models of the gravity field are analyzed and compared. A high-low configuration satellite-to-satellite tracking mission is recommended for the determination of both the long wavelength and short wavelength portions of the field. Satellite altimetry and satellite gradiometry missions are recommended for determination of the short wavelength portion of the field.

  14. Whiteheadian Actual Entitities and String Theory

    NASA Astrophysics Data System (ADS)

    Bracken, Joseph A.

    2012-06-01

    In the philosophy of Alfred North Whitehead, the ultimate units of reality are actual entities, momentary self-constituting subjects of experience which are too small to be sensibly perceived. Their combination into "societies" with a "common element of form" produces the organisms and inanimate things of ordinary sense experience. According to the proponents of string theory, tiny vibrating strings are the ultimate constituents of physical reality which in harmonious combination yield perceptible entities at the macroscopic level of physical reality. Given that the number of Whiteheadian actual entities and of individual strings within string theory are beyond reckoning at any given moment, could they be two ways to describe the same non-verifiable foundational reality? For example, if one could establish that the "superject" or objective pattern of self- constitution of an actual entity vibrates at a specific frequency, its affinity with the individual strings of string theory would be striking. Likewise, if one were to claim that the size and complexity of Whiteheadian 'societies" require different space-time parameters for the dynamic interrelationship of constituent actual entities, would that at least partially account for the assumption of 10 or even 26 instead of just 3 dimensions within string theory? The overall conclusion of this article is that, if a suitably revised understanding of Whiteheadian metaphysics were seen as compatible with the philosophical implications of string theory, their combination into a single world view would strengthen the plausibility of both schemes taken separately. Key words: actual entities, subject/superjects, vibrating strings, structured fields of activity, multi-dimensional physical reality.

  15. Effect of magnetic field fluctuation on ultra-low field MRI measurements in the unshielded laboratory environment

    NASA Astrophysics Data System (ADS)

    Liu, Chao; Chang, Baolin; Qiu, Longqing; Dong, Hui; Qiu, Yang; Zhang, Yi; Krause, Hans-Joachim; Offenhäusser, Andreas; Xie, Xiaoming

    2015-08-01

    Magnetic field fluctuations in our unshielded urban laboratory can reach hundreds of nT in the noisy daytime and is only a few nT in the quiet midnight. The field fluctuation causes the Larmor frequency fL to drift randomly for several Hz during the unshielded ultra-low field (ULF) nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) measurements, thus seriously spoiling the averaging effect and causing imaging artifacts. By using an active compensation (AC) technique based on the spatial correlation of the low-frequency magnetic field fluctuation, the field fluctuation can be suppressed to tens of nT, which is a moderate situation between the noisy daytime and the quiet midnight. In this paper, the effect of the field fluctuation on ULF MRI measurements was investigated. The 1D and 2D MRI signals of a water phantom were measured using a second-order low-Tc superconducting quantum interference device (SQUID) in three fluctuation cases: severe fluctuation (noisy daytime), moderate fluctuation (daytime with AC) and minute fluctuation (quiet midnight) when different gradient fields were applied. When the active compensation is applied or when the frequency encoding gradient field Gx reaches a sufficiently strong value in our measurements, the image artifacts become invisible in all three fluctuation cases. Therefore it is feasible to perform ULF-MRI measurements in unshielded urban environment without imaging artifacts originating from magnetic fluctuations by using the active compensation technique and/or strong gradient fields.

  16. Effect of magnetic field fluctuation on ultra-low field MRI measurements in the unshielded laboratory environment.

    PubMed

    Liu, Chao; Chang, Baolin; Qiu, Longqing; Dong, Hui; Qiu, Yang; Zhang, Yi; Krause, Hans-Joachim; Offenhäusser, Andreas; Xie, Xiaoming

    2015-08-01

    Magnetic field fluctuations in our unshielded urban laboratory can reach hundreds of nT in the noisy daytime and is only a few nT in the quiet midnight. The field fluctuation causes the Larmor frequency fL to drift randomly for several Hz during the unshielded ultra-low field (ULF) nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) measurements, thus seriously spoiling the averaging effect and causing imaging artifacts. By using an active compensation (AC) technique based on the spatial correlation of the low-frequency magnetic field fluctuation, the field fluctuation can be suppressed to tens of nT, which is a moderate situation between the noisy daytime and the quiet midnight. In this paper, the effect of the field fluctuation on ULF MRI measurements was investigated. The 1D and 2D MRI signals of a water phantom were measured using a second-order low-Tc superconducting quantum interference device (SQUID) in three fluctuation cases: severe fluctuation (noisy daytime), moderate fluctuation (daytime with AC) and minute fluctuation (quiet midnight) when different gradient fields were applied. When the active compensation is applied or when the frequency encoding gradient field Gx reaches a sufficiently strong value in our measurements, the image artifacts become invisible in all three fluctuation cases. Therefore it is feasible to perform ULF-MRI measurements in unshielded urban environment without imaging artifacts originating from magnetic fluctuations by using the active compensation technique and/or strong gradient fields. PMID:26037135

  17. Comparison of the measurement standards of the length unit in the field of roundness deviations measurements

    NASA Astrophysics Data System (ADS)

    Lysenko, V. G.; Kupko, V. S.; Makarevich, V. B.

    2016-01-01

    A trilateral comparison has been performed in the subject field of roundness measurement. The comparison was pilot by VNIIMS, Russia and took place between February 2014 and August 2014. The circulated standards were a roundness transfer standard in the form of a glass hemisphere and a magnification standard often referred to as a 'Flick' standard. Data from the roundness standard were processed using a Gaussian filter and a bandpass up to 50 undulations per revolution to provide a measured value of Roundness Deviation (RONt). For the magnification standard, data were also filtered and the fitted element was the circumscribed circle together with the deviation of the valleys (RONv). The results of comparisons show the correspondence of measurement uncertainties to the declared values and the compared measurement standards are equivalent. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCL, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  18. Magnetic Field Measurements Based on Terfenol Coated Photonic Crystal Fibers

    PubMed Central

    Quintero, Sully M. M.; Martelli, Cicero; Braga, Arthur M. B.; Valente, Luiz C. G.; Kato, Carla C.

    2011-01-01

    A magnetic field sensor based on the integration of a high birefringence photonic crystal fiber and a composite material made of Terfenol particles and an epoxy resin is proposed. An in-fiber modal interferometer is assembled by evenly exciting both eigenemodes of the HiBi fiber. Changes in the cavity length as well as the effective refractive index are induced by exposing the sensor head to magnetic fields. The magnetic field sensor has a sensitivity of 0.006 (nm/mT) over a range from 0 to 300 mT with a resolution about ±1 mT. A fiber Bragg grating magnetic field sensor is also fabricated and employed to characterize the response of Terfenol composite to the magnetic field. PMID:22247655

  19. Three-Dimensional Quantitative Optical Measurement of Asymmetrically Focused Ultrasound Pressure Field

    NASA Astrophysics Data System (ADS)

    Shimazaki, Yuta; Harigane, Soichiro; Yoshizawa, Shin; Umemura, Shin-ichiro

    2012-07-01

    High-intensity focused ultrasound (HIFU) is used for the treatment of tumors such as prostate cancer. In the development of this technique, an accurate and fast measurement of the HIFU pressure field is important. A hydrophone is generally used for the measurement, but it might disturb the pressure field and scanning it in the field takes a long time. On the other hand, optical ultrasonic field mapping has the advantages of speed and its nature of not by interfering with the acoustic field. In this study, we reconstructed an asymmetric ultrasound field by optical measurement using a computed tomography (CT) algorithm. The asymmetric field was generated by a focused transducer with four elements. Also, the absolute measurement of ultrasonic pressure was checked by measuring the center of the field of the charge-coupled device (CCD) camera. The results showed overall agreement with those of hydrophone measurement.

  20. Measured Effects of a Longitudinal Solenoidal Field on an Iron Quadrupole

    NASA Astrophysics Data System (ADS)

    Ecklund, S.; Seeman, J. T.; Wolf, Z.

    1997-05-01

    We have measured the effects of a longitudinal solenoidal field on the field harmonics of an iron dominated quadrupole. These measurements are useful when designing a colliding beam interaction region where the first quadrupole is very near the solenoidal field of the physics detector. The effects of mirror plates, quadrupole excition, skew quadrupole windings, dipole windings, and solenoidal fields that enter at an angle have been measured. Conclusions and interpretations are given.

  1. The 2013 Arctic Field Season of the NRL Sea-Ice Measurement Program

    NASA Astrophysics Data System (ADS)

    Gardner, J. M.; Brozena, J. M.; Ball, D.; Hagen, R. A.; Liang, R.; Stoudt, C.

    2013-12-01

    The U.S. Naval Research Laboratory (NRL) is conducting a five year study of the changing Arctic with a particular focus on ice thickness and distribution variability with the intent of optimizing state-of-the-art computer models which are currently used to predict sea ice changes. An important part of our study is to calibrate/validate CryoSat2 ice thickness data prior to its incorporation into new ice forecast models. NRL Code 7420 collected coincident data with the CryoSat2 satellite in 2011 and 2012 using a LiDAR (Riegl Q560) to measure combined snow and ice thickness and a 10 GHz pulse-limited precision radar altimeter to measure sea-ice freeboard. This field season, LiDAR data was collected using the Riegl Q680 which permitted higher density operation and data collection. Concident radar data was collected using an improved version of the NRL 10 GHz pulse limited radar that was used for the 2012 fieldwork. 8 coincident tracks of CryoSat2 satellite data were collected. Additionally a series of grids (7 total) of adjacent tracks were flown coincident with Cryosat2 satellite overpass. These grids cover the approximate satellite footprint of the satellite on the ice as it passes overhead. Data from these grids are shown here and will be used to examine the relationship of the tracked satellite waveform data to the actual surface across the footprint. We also coordinated with the Seasonal Ice Zone Observing Network (SIZONet) group who conducted surface based ice thickness surveys using a Geonics EM-31 along hunter trails on the landfast ice near Barrow as well as on drifting ice offshore during helicopter landings. On two sorties, a twin otter carrying the NRL LiDAR and radar altimeter flew in tandem with the helicopter carrying the EM-31 to achieve synchronous data acquisition. Data from these flights are shown here along with a digital elevation map.

  2. Separation of field-independent and field-dependent susceptibility tensors using a sequence of fully automated AMS measurements

    NASA Astrophysics Data System (ADS)

    Studynka, J.; Chadima, M.; Hrouda, F.; Suza, P.

    2013-12-01

    Low-field magnetic susceptibility of diamagnetic and paramagnetic minerals as well as that of pure magnetite and all single-domain ferromagnetic (s.l.) minerals is field-independent. In contrast, magnetic susceptibility of multi-domain pyrrhotite, hematite and titanomagnetite may significantly depend on the field intensity. Hence, the AMS data acquired in various fields have a great potential to separate the magnetic fabric carried by the latter group of minerals from the whole-rock fabric. The determination of the field variation of AMS consist of separate measurements of each sample in several fields within the Rayleigh Law range and subsequent processing in which the field-independent and field-dependent susceptibility tensors are calculated. The disadvantage of this technique is that each sample must be measured several times in various positions, which is relatively laborious and time consuming. Recently, a new 3D rotator was developed for the MFK1 Kappabridges which rotates the sample simultaneously about two axes with different velocities. The measurement is fully automated in such a way that, once the sample is mounted into the rotator, it requires no additional positioning to measure the full AMS tensor. The important advantage of the 3D rotator is that it enables to measure AMS in a sequence of pre-set field intensities without any operator manipulation. Whole procedure is computer-controlled and, once a sequence of measurements is finished, the acquired data are immediately processed and visualized. Examples of natural rocks demonstrating various types of field dependence of AMS are given.

  3. Temperature field measurement as quality assurance measure in case of laser material processing

    NASA Astrophysics Data System (ADS)

    Jurca, Marius; Langer, Hans-Jürgen

    The paper presents the results of the development of a new real-time quality assurance sensor. The Temperature Field Sensor is capable to offer a more direct interpretation of the monitoring results in correlation with the processing results and settings. The sensor delivers a temperature map of the heat-affected zone independent from processing parameters like welding speed. Using fibre optics, the sensor head of the new monitoring system has a small size matching the requirements for integration even in case of 3D-applications. The simultaneous acquisition of the distance and of the surface emissivity for each measuring point enables the system to monitor also lowemissivity materials like Aluminium. There is no limitation concerning the geometry of the joints to be monitored.

  4. Measuring bi-directional current through a field-effect transistor by virtue of drain-to-source voltage measurement

    DOEpatents

    Turner, Steven Richard

    2006-12-26

    A method and apparatus for measuring current, and particularly bi-directional current, in a field-effect transistor (FET) using drain-to-source voltage measurements. The drain-to-source voltage of the FET is measured and amplified. This signal is then compensated for variations in the temperature of the FET, which affects the impedance of the FET when it is switched on. The output is a signal representative of the direction of the flow of current through the field-effect transistor and the level of the current through the field-effect transistor. Preferably, the measurement only occurs when the FET is switched on.

  5. 47 CFR 73.153 - Field strength measurements in support of applications or evidence at hearings.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 47 Telecommunication 4 2010-10-01 2010-10-01 false Field strength measurements in support of... (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.153 Field strength..., groundwave field strength measurements will take precedence over theoretical values, provided...

  6. 47 CFR 73.153 - Field strength measurements in support of applications or evidence at hearings.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 47 Telecommunication 4 2011-10-01 2011-10-01 false Field strength measurements in support of... (CONTINUED) BROADCAST RADIO SERVICES RADIO BROADCAST SERVICES AM Broadcast Stations § 73.153 Field strength..., groundwave field strength measurements will take precedence over theoretical values, provided...

  7. [Welding arc temperature field measurements based on Boltzmann spectrometry].

    PubMed

    Si, Hong; Hua, Xue-Ming; Zhang, Wang; Li, Fang; Xiao, Xiao

    2012-09-01

    Arc plasma, as non-uniform plasma, has complicated energy and mass transport processes in its internal, so plasma temperature measurement is of great significance. Compared with absolute spectral line intensity method and standard temperature method, Boltzmann plot measuring is more accurate and convenient. Based on the Boltzmann theory, the present paper calculates the temperature distribution of the plasma and analyzes the principle of lines selection by real time scanning the space of the TIG are measurements. PMID:23240385

  8. Low-field magnetoacoustic residual stress measurement in steel

    NASA Technical Reports Server (NTRS)

    Namkung, M.; Utrata, D.; Heyman, J. S.; Allison, S. G.

    1987-01-01

    Much of the recent development of the magnetoacoustic technique has been devoted to refine this technique as a reliable and practical tool for measuring bulk residual stress in steel components. For this, the effects of structural and metallurgical properties on the magnetoacoustic interaction have been studied for various types of steel samples. Also, progress is being made to obtain quantitative residual stress measurements in railroad wheels. This paper reviews the physical basis and the experimental results of the magnetoacoustic stress measurements in steels.

  9. Electromagnetic Near Field Measurements of Two Critical Assemblies

    SciTech Connect

    Goettee, Jeffrey David

    2015-11-03

    The reactors employed, Godiva IV and WSMR Fast Burst Reactor, are described first. Then the point reactor kinetics model, electromagnetic potential, and the measurement of kinetics quantities are successively discussed. In summary, reactor power produces measurable electric energy. The electric signal mimics power curve for prompt burst operations - features in logarithmic derivatives match. The electric signature should be dependent on the power and not the derivative; therefore, steady-state modes should be measurable.

  10. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., such as topography, height and types of vegetation, buildings, obstacles, weather, and other local... the approximate time of measurement, weather, topography, overhead wiring, heights and types...

  11. Solar magnetic fields measurements with a magneto-optical filter

    NASA Technical Reports Server (NTRS)

    Cacciani, A.; Ricci, D.; Rosati, P.; Rhodes, E. J.; Smith, E.

    1990-01-01

    The presence of a magnetic field at different levels inside the sun has crucial implications for helioseismology. The solar oscillation observing program carried out since 1983 at Mt. Wilson with Cacciani magneto-optical filter has recently been modified to acquire full-disk magnetograms with 2 arcsec spatial resolution. A method for the correct determination of magnetic maps which are free of contamination by velocity signal is presented. It is shown that no cross-talk exists between the Doppler and Zeeman shifts of the Na D lines, provided that instrumental polarization effects are taken into account. The observed line-of-sight photospheric field was used to map the vector field in the inner corona, above active regions, in the current free approximation.

  12. Measurement of low frequency magnetic fields from digital cellular telephones

    SciTech Connect

    Linde, T.; Mild, K.H.

    1997-05-01

    All previous discussions about possible health effects in connection with the use of digital cellular telephones have been focused on the microwaves. However, the pulsed transmitting mode causes pulsed currents in the phone and the battery pack, which give rise to concomitant magnetic fields. Digital cellular telephones using the GSM (Global System for Mobile Communication) transmit information in bursts of microwaves. This pulsed transmitting mode causes the battery current and currents in the electronics of the apparatus to be pulsed. These pulsed currents produce corresponding pulsed magnetic fields near the phones. A study to determine the magnitude of these fields involved two models of digital telephones. The highest value of the magnetic flux density was 1.8 {micro}T (rms).

  13. Hazard surveillance for workplace magnetic fields. 1: Walkaround sampling method for measuring ambient field magnitude; 2: Field characteristics from waveform measurements

    SciTech Connect

    Methner, M.M.; Bowman, J.D.

    1998-03-01

    Recent epidemiologic research has suggested that exposure to extremely low frequency (ELF) magnetic fields (MF) may be associated with leukemia, brain cancer, spontaneous abortions, and Alzheimer`s disease. A walkaround sampling method for measuring ambient ELF-MF levels was developed for use in conducting occupational hazard surveillance. This survey was designed to determine the range of MF levels at different industrial facilities so they could be categorized by MF levels and identified for possible subsequent personal exposure assessments. Industries were selected based on their annual electric power consumption in accordance with the hypothesis that large power consumers would have higher ambient MFs when compared with lower power consumers. Sixty-two facilities within thirteen 2-digit Standard Industrial Classifications (SIC) were selected based on their willingness to participate. A traditional industrial hygiene walkaround survey was conducted to identify MF sources, with a special emphasis on work stations.

  14. Electric field measuring and display system. [for cloud formations

    NASA Technical Reports Server (NTRS)

    Wojtasinski, R. J.; Lovall, D. D. (Inventor)

    1974-01-01

    An apparatus is described for monitoring the electric fields of cloud formations within a particular area. It utilizes capacitor plates that are alternately shielded from the clouds for generating an alternating signal corresponding to the intensity of the electric field of the clouds. A synchronizing signal is produced for controlling sampling of the alternating signal. Such samplings are fed through a filter and converted by an analogue to digital converter into digital form and subsequently fed to a transmitter for transmission to the control station for recording.

  15. A quasi-optical vector near-field measurement system at terahertz band.

    PubMed

    Lou, Zheng; Hu, Jie; Zhou, Kang-Min; Miao, Wei; Shi, Sheng-Cai

    2014-06-01

    This paper describes a vector near-field measurement system at terahertz band based on a high sensitivity superconducting receiver equipped with a quasi-optical probe for high resolution near-field sensing. A novel single-receiver rather than commonly used dual-receiver configuration is adopted for vector measurement. Performances of the measurement system including stability and dynamic range are studied. Vector near-field measurement of a diagonal feedhorn at 850 GHz is presented and shows good agreement with simulation and direct far-field measurement. PMID:24985832

  16. Water temperature-influential factors, field measurement, and data presentation

    USGS Publications Warehouse

    Stevens, Herbert H.; Ficke, John F.; Smoot, George F.

    1975-01-01

    This manual contains suggested procedures for collecting and reporting of water-temperature data on streams, lakes and reservoirs, estuaries, and ground water. Among the topics discussed are the selection of equipment and measuring sites, objectives and accuracy of measurements, and data processing and presentation. Background information on the influence of temperature on water quality and the factors influencing water temperature are also presented.

  17. DENSE GAS PLUME FIELD MEASUREMENTS AT THE NEVADA TEST SITE

    EPA Science Inventory

    Field experiments on dense gas diffusion carried out at the Spills Test Facility on the Nevada Test Site are briefly described, including four "baseline" releases made in July 1993 and two new series planned for August-September 1995. he first series will target neutral to very s...

  18. MEASUREMENT OF SMALL MECHANICAL VIBRATIONS OF BRAIN TISSUE EXPOSED TO EXTREMELY-LOW-FREQUENCY ELECTRIC FIELDS

    EPA Science Inventory

    Electromagnetic fields can interact with biological tissue both electrically and mechanically. This study investigated the mechanical interaction between brain tissue and an extremely-low-frequency (ELF) electric field by measuring the resultant vibrational amplitude. The exposur...

  19. Environmental Measurement in Schools: Electronics in Field Studies.

    ERIC Educational Resources Information Center

    Crellin, J. R.

    1978-01-01

    The use of environmental meters designed to measure conductivity, light level, oxygen, pH, sound, and temperature are discussed. Criteria for choosing suitable equipment are suggested and, where possible, cheaper alternatives are mentioned. (Author/BB)

  20. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ..., such as topography, height and types of vegetation, buildings, obstacles, weather, and other local... approximate time of measurement, weather, topography, overhead wiring, heights and types of vegetation... as topography, height and types of vegetation, buildings, obstacles, weather, and other...

  1. FIELD MEASUREMENT OF DISSOLVED OXYGEN: A COMPARISON OF TECHNIQUES

    EPA Science Inventory

    The measurement and interpretation of geochemical redox parameters are key components of ground water remedial investigations. Dissolved oxygen (DO) is perhaps the most robust geochemical parameter in redox characterization; however, recent work has indicated a need for proper da...

  2. Aircraft measurements and analysis of severe storms: 1976 field experiment

    NASA Technical Reports Server (NTRS)

    Sinclair, P. C.

    1982-01-01

    Severe storm aircraft measurements are documented, as well as the instrumentation and operational features of aircraft mobility capabilities. The measurements and data analyses indicate that the concept of a highly mobile research aircraft capability for obtaining detailed measurements of wind, temperature, moisture, spherics, etc., near and within severe storm systems, forecast 48 hours in advance in a 1000 nm operating radius, is feasible, and was successfully demonstrated. The measurements and analyses reveal several severe storm features and insights with respect to storm air flow circulations and inflow-outflow orientation. Precipitation downdraft air is recirculated back into the updraft core below the scud cloud in both back and front feeder type storms. In a back feeder type storm, the downdraft outflow air ahead of the storm is also recirculated back into the updraft region near cloud base.

  3. Rapid subsidence over oil fields measured by SAR

    NASA Technical Reports Server (NTRS)

    Fielding, E. J.; Blom, R. G.; Goldstein, R. M.

    1998-01-01

    The Lost Hills and Belridge oil felds are in the San Joaquin Valley, California. The major oil reservoir is high porosity and low permeability diatomite. Extraction of large volumes from shallow depths causes reduction in pore pressure and subsequent compaction, forming a surface subsidence bowl. We measure this subsidence from space using interferometric analysis of SAR (Synthetic Aperture Radar) data collected by the European Space Agency Remote Sensing Satellites (ERS-1 and ERS-2). Maximum subsidence rates are as high as 40 mm in 35 days or > 400 mm/yr, measured from interferograms with time separations ranging from one day to 26 months. The 8- and 26-month interferograms contain areas where the subsidence gradient exceeds the measurement possible with ERS SAR, but shows increased detail in areas of less rapid subsidence. Synoptic mapping of subsidence distribution from satellite data powerfully complements ground-based techniques, permits measurements where access is difficult, and aids identification of underlying causes.

  4. On Cirrus Cloud Fields Measured by the Atmospheric Infrared Sounder

    NASA Technical Reports Server (NTRS)

    Kahn, Brian H.; Eldering, Annmarie; Liou, Kuo Nan

    2006-01-01

    A viewgraph presentation showing trends in clouds measured by the Atmospheric Infrared Sounder (AIRS) is given. The topics include: 1) Trends in clouds measured by AIRS: Are they reasonable? 2) Single and multilayered cloud trends; 3) Retrievals of thin cirrus D(sub e) and tau: Single-layered cloud only; 4) Relationships between ECF, D(sub e), tau, and T(sub CLD); and 5) MODIS vs. AIRS retrievals.

  5. Mass spectroscopy of single aerosols from field measurements

    SciTech Connect

    Thomson, D.S.; Murphy, D.M.

    1995-12-31

    We are developing an aircraft instrument for the chemical analysis of individual ambient aerosols in real time. In order to test the laboratory version of this instrument, we participated in a field campaign near the continental divide in Colorado in September, 1993. During this campaign, over 5000 mass spectra of ambient aerosols were collected. Analysis of the negative ion spectra shows that sulfate was the most commonly seen component of smaller particles, while nitrate was more common in larger particles. Organic compounds are present in most particles, and we believe we can distinguish inorganic carbon in some particles. Although numerous distinct classes of particles were observed, indicating external mixtures, almost all of these particle types were themselves mixtures of several compounds. Finally, we note that although the field site experienced distinct polluted and unpolluted episodes, aerosol composition did not correlate with gas phase chemistry.

  6. Magnetic field of the planet Uranus: predictions, measurements, and interpretation

    SciTech Connect

    Dolginov, S.S.

    1987-09-01

    The magnitude and tilt of the eccentric dipole of Uranus are examined in the framework of a processing dynamo model. It is shown that the unique parameters of the magnetic field of Uranus are connected with the fact that, unlike the other planets, the magnetic field of Uranus is generated in two bordering regions whose highly conducting materials differ sharply in density: the density anti rho = 12 g x cm/sup -3/ in a core with an upper boundary r = 0.3R/sub U/, and anti rho = 3.1 g x cm/sup -3/ in an ocean with an upper boundary r = 0.6R/sub U/. The upper boundary of the magnetically active region in the ocean is determined by the magnetic pressure P = 1.9 Mbar, at which the ocean material is metallized.

  7. Microspacecraft and Earth observation: Electrical field (ELF) measurement project

    NASA Technical Reports Server (NTRS)

    Olsen, Tanya; Elkington, Scot; Parker, Scott; Smith, Grover; Shumway, Andrew; Christensen, Craig; Parsa, Mehrdad; Larsen, Layne; Martinez, Ranae; Powell, George

    1990-01-01

    The Utah State University space system design project for 1989 to 1990 focuses on the design of a global electrical field sensing system to be deployed in a constellation of microspacecraft. The design includes the selection of the sensor and the design of the spacecraft, the sensor support subsystems, the launch vehicle interface structure, on board data storage and communications subsystems, and associated ground receiving stations. Optimization of satellite orbits and spacecraft attitude are critical to the overall mapping of the electrical field and, thus, are also included in the project. The spacecraft design incorporates a deployable sensor array (5 m booms) into a spinning oblate platform. Data is taken every 0.1 seconds by the electrical field sensors and stored on-board. An omni-directional antenna communicates with a ground station twice per day to down link the stored data. Wrap-around solar cells cover the exterior of the spacecraft to generate power. Nine Pegasus launches may be used to deploy fifty such satellites to orbits with inclinations greater than 45 deg. Piggyback deployment from other launch vehicles such as the DELTA 2 is also examined.

  8. Impact of magnetic field on radial velocity measurements.

    NASA Astrophysics Data System (ADS)

    Hébrard, E. M.; Delfosse, X.; Morin, J.; Boisse, I.; Moutou, C.; Hébrard, G.

    2014-12-01

    Very low-mass stars are very promising targets for planet-search programs, in particular to discover super-Earths / Earths located in their habitable zone. Their detection is in principle accessible to the existing velocimeters of highest radial-velocity (RV) precision, but challenging due to activity ( i.e., dark spots and magnetic regions at their surfaces) which generate a noise level in RV curves (RV jitter). It can severely limit our practical ability at detecting Earth-like planets. To overcome this intrinsic limitation, a promising option consists in modeling directly the stellar activity behind the activity jitter, and in particular the magnetic field that gives rise to it. To do this, simultaneous observations in velocimetry (for activity jitter) and in spectropolarimetry (for the Zeeman signatures in spectral lines tracing the presence of a large-scale field) are needed. We present here our first results both on the simulations on the impact of magnetic fields on line profiles (bisectors & RV data), and on the simultaneous observations done thanks to HARPSPol@LaSilla and NARVAL@TBL/SOPHIE@OHP on a small sample.

  9. Microspacecraft and Earth observation: Electrical field (ELF) measurement project

    NASA Astrophysics Data System (ADS)

    Olsen, Tanya; Elkington, Scot; Parker, Scott; Smith, Grover; Shumway, Andrew; Christensen, Craig; Parsa, Mehrdad; Larsen, Layne; Martinez, Ranae; Powell, George

    The Utah State University space system design project for 1989 to 1990 focuses on the design of a global electrical field sensing system to be deployed in a constellation of microspacecraft. The design includes the selection of the sensor and the design of the spacecraft, the sensor support subsystems, the launch vehicle interface structure, on board data storage and communications subsystems, and associated ground receiving stations. Optimization of satellite orbits and spacecraft attitude are critical to the overall mapping of the electrical field and, thus, are also included in the project. The spacecraft design incorporates a deployable sensor array (5 m booms) into a spinning oblate platform. Data is taken every 0.1 seconds by the electrical field sensors and stored on-board. An omni-directional antenna communicates with a ground station twice per day to down link the stored data. Wrap-around solar cells cover the exterior of the spacecraft to generate power. Nine Pegasus launches may be used to deploy fifty such satellites to orbits with inclinations greater than 45 deg. Piggyback deployment from other launch vehicles such as the DELTA 2 is also examined.

  10. Measuring solar magnetic fields with artificial neural networks.

    PubMed

    Socas-Navarro, Hector

    2003-01-01

    The quantification of the solar magnetic field is a crucial step in modern solar physics to understand the dynamics, activity and variability of our star. Presently, a reliable inference of these fields is only possible by means of a computer-intensive process that has so far limited scientists to the analysis of observations from small regions of the solar disk, and/or very crude spatial and temporal resolution. This work presents a different approach to the problem, in which a multilayer perceptron, trained with known synthetic profiles, is able to recognize the profiles and return the magnetic field used to synthesize them. The network is then confronted with real observations of a sunspot which had been previously inverted using traditional inversion techniques. A quantitative comparison between these two procedures shows the reliability of the network when applied to points having magnetic filling factors larger than approximately 70%. The dramatic decrease in the required computing time presents an opportunity for the routine analysis of large-scale, high-resolution solar observations. PMID:12672431

  11. Measured ground-surface movements, Cerro Prieto geothermal field

    SciTech Connect

    Massey, B.L.

    1981-01-01

    The Cerro Prieto geothermal area in the Mexicali Valley, 30 kilometers southeast of Mexicali, Baja California, incurred slight deformation because of the extraction of hot water and steam, and probably, active tectonism. During 1977 to 1978, the US Geological Survey established and measured two networks of horizontal control in an effort to define both types of movement. These networks consisted of: (1) a regional trilateration net brought into the mountain ranges west of the geothermal area from stations on an existing US Geological Survey crustal-strain network north of the international border; and (2) a local net tied to stations in the regional net and encompassing the present and planned geothermal production area. Electronic distance measuring instruments were used to measure the distances between stations in both networks in 1978, 1979 and 1981. Lines in the regional net averaged 25 km. in length and the standard deviation of an individual measurement is estimated to be approx. 0.3 part per million of line length. The local network was measured using different instrumentation and techniques. The average line length was about 5 km. and the standard deviation of an individual measurement approached 3 parts per million per line length. Ground-surface movements in the regional net, as measured by both the 1979 and 1981 resurveys, were small and did not exceed the noise level. The 1979 resurvey of the local net showed an apparent movement of 2 to 3 centimeters inward toward the center of the production area. This apparent movement was restricted to the general limits of the production area. The 1981 resurvey of the local net did not show increased movement attributable to fluid extraction.

  12. Using impedance measurements for detecting pathogens trapped in an electric field

    DOEpatents

    Miles, Robin R.

    2004-07-20

    Impedance measurements between the electrodes in an electric field is utilized to detect the presence of pathogens trapped in the electric field. Since particles trapped in a field using the dielectiphoretic force changes the impedance between the electrodes by changing the dielectric material between the electrodes, the degree of particle trapping can be determined by measuring the impedance. This measurement is used to determine if sufficient pathogen have been collected to analyze further or potentially to identify the pathogen.

  13. Development of wireless communication system in real-time internal radiation dose measurement system using magnetic field

    NASA Astrophysics Data System (ADS)

    Sato, Fumihiro; Shinohe, Kohta; Takura, Tetsuya; Matsuki, Hidetoshi; Yamada, Syogo; Sato, Tadakuni

    2009-04-01

    In radiation therapy, excessive radiation occurs because the actual delivered dose to the tumor is unknown. To overcome this problem, we need a system in which the delivered dose is measured inside the body, and the dose data are transmitted from the inside to the outside of the body. In this study, a wireless communication system, using magnetic fields was studied, and an internal circuit for obtaining radiation dose data from an x-ray detector was examined. As a result, a communication distance of 200 mm was obtained. An internal circuit was developed, and a signal transmission experiment was performed using the wireless communication system. As a result, the radiation dose data from an x-ray detector was transmitted over a communication distance of 200 mm, and the delivered dose was determined from the received signal.

  14. Compact airborne lidar for tropospheric ozone: description and field measurements.

    PubMed

    Ancellet, G; Ravetta, F O

    1998-08-20

    An airborne lidar has been developed for tropospheric ozone monitoring. The transmitter module is based on a solid-state Nd:YAG laser and stimulated Raman scattering in deuterium to generate three wavelengths (266, 289, and 316 nm) that are used for differential ozone measurements. Both analog and photon-counting detection methods are used to produce a measurement range up to 8 km. The system has been flown on the French Fokker 27 aircraft to perform both lower tropospheric (0.5-4-km) and upper tropospheric (4-12-km) measurements, with a 1-min temporal resolution corresponding to a 5-km spatial resolution. The vertical resolution of the ozone profile can vary from 300 to 1000 m to accommodate either a large-altitude range or optimum ozone accuracy. Comparisons with in situ ozone measurements performed by an aircraft UV photometer or ozone sondes and with ozone vertical profiles obtained by a ground-based lidar are presented. The accuracy of the tropospheric ozone measurements is generally better than 10-15%, except when aerosol interferences cannot be corrected. Examples of ozone profiles for different atmospheric conditions demonstrate the utility of the airborne lidar in the study of dynamic or photochemical mesoscale processes that control tropospheric ozone. PMID:18286036

  15. Measurement of GHz range magnetic field distribution near a coplanar waveguide using a beating field-type magnetic force microscope

    NASA Astrophysics Data System (ADS)

    Endo, Y.; Fukushima, M.; Arai, K.; Yanagi, K.; Shimada, Y.; Yamaguchi, M.

    2014-05-01

    This paper describes the measurement of microscopic radio frequency (RF) field distribution with a magnetic force microscope (MFM) tip exploring the beat signal from a coplanar waveguide (CPW) with a signal line as fine as 5 μm and a ground line of 50 μm. To produce a beating field in close proximity to the CPW, two RF currents with slightly different frequencies are supplied, where one is the signal current with a fixed frequency of 1.1 GHz and the other is the reference. The reference is adjusted to produce a beat with a frequency near the cantilever mechanical resonance frequency. Thus, the mechanical resonance of the cantilever excited by the beat field includes information about the 1.1 GHz field distribution from the CPW signal current. Detection of a beating field with a MFM tip can provide very high resolutions of the RF field distribution in the proximity of RF circuit component.

  16. Flow field measurements in a 90 degree turning duct

    NASA Technical Reports Server (NTRS)

    Crawford, Roger A.; Peters, Carroll E.

    1985-01-01

    The objective of this investigation is the experimental evaluation of the influence of inlet turbulence intensity on secondary flow development in a turning duct. The existing 25.4 cm square turning duct (90) facility is being utilized to investigate of bulk turbulence levels on secondary flow development. The large scale duct flow facility allows detailed mean velocity and turbulence quantities to be measured at several streamwise planes in the curved duct. Non-intrusive laser velocimetry is being used to measure the mean and fluctuating components of velocity in all three orthogonal directions. To assure that the turbulence measurements are unbiased by particle lag and other effects, comparison hot wire data will be taken to validate the laser velocimetry system calibration.

  17. Venera-9 magnetic field measurements in the Venus wake - Evidence for an earth-like interaction

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1976-01-01

    Venera-9 magnetic field measurements in the Venus wake provide additional support for the hypothesis that Venus has an intrinsic planetary field. The observed field is in the direction expected for a northward moment, and is similar to that observed in equivalent locations in the terrestrial magnetosphere, both in its temporal and spatial behavior. In particular, Venera-9 appears to have observed a plasma sheet expansion, field-aligned currents, and tail-field dipolarization.

  18. Microfabricated atomic vapor cell arrays for magnetic field measurements

    SciTech Connect

    Woetzel, S.; Schultze, V.; IJsselsteijn, R.; Schulz, T.; Anders, S.; Stolz, R.; Meyer, H.-G.

    2011-03-15

    We describe a method for charging atomic vapor cells with cesium and buffer gas. By this, it is possible to adjust the buffer gas pressure in the cells with good accuracy. Furthermore, we present a new design of microfabricated vapor cell arrays, which combine silicon wafer based microfabrication and ultrasonic machining to achieve the arrays of thermally separated cells with 50 mm{sup 3} volume. With cells fabricated in the outlined way, intrinsic magnetic field sensitivities down to 300 fT/Hz{sup 1/2} are reached.

  19. Field evaluation of environmental sanitation measures against cholera*

    PubMed Central

    Azurin, J. C.; Alvero, M.

    1974-01-01

    Data obtained in a controlled field study over 5 years in 4 communities showed that the provision of sanitary facilities for human waste disposal can reduce the incidence of cholera by as much as 68%, while the provision of a safe water supply can decrease it by 73%. Where both toilets and water supplies are provided, the incidence can be reduced by as much as 76%. There was evidence that cholera infection gaining access to communities with these facilities tends to spread less and produce fewer secondary cases than in a community where such facilities are not provided. PMID:4549038

  20. Field evaluation of environmental sanitation measures against cholera.

    PubMed

    Azurin, J C; Alvero, M

    1974-01-01

    Data obtained in a controlled field study over 5 years in 4 communities showed that the provision of sanitary facilities for human waste disposal can reduce the incidence of cholera by as much as 68%, while the provision of a safe water supply can decrease it by 73%. Where both toilets and water supplies are provided, the incidence can be reduced by as much as 76%. There was evidence that cholera infection gaining access to communities with these facilities tends to spread less and produce fewer secondary cases than in a community where such facilities are not provided. PMID:4549038

  1. Measurement of displacement vector fields of extended objects

    NASA Astrophysics Data System (ADS)

    Osten, Wolfgang; Jüptner, Werner

    The main effort in laser metrology during the last 15 years has been focussed on the development of high precision phase measurement techniques, since the phase is the primary quantity for interferometrical testing. However, the phase distribution gives only a first impression of the deformation of the surface. In practice, the three-dimensional displacement components are required if the mechanical behaviour of the object under load is to be investigated. To calculate displacement components some further quantities are necessary, e.g. the three coordinates of the object points. Although the contour measurement can also be reduced to a phase measurement problem, the measurement of three-dimensional displacements is more complex than a high precision phase evaluation. From the practical point of view, four main tasks have to be performed: planning of the experiment, design of the interferometer, acquisition of data and evaluation of data. This paper deals with a discussion of the theoretical background of the last three procedures concerning the state of the art and describes some general rules as well as some problems remaining to be solved for the investigation of extended specimens.

  2. IN SITU FIELD PORTABLE FINE PARTICLE MEASURING DEVICE

    EPA Science Inventory

    The report describes the design, development, and testing of an in situ fine particle measuring device--the Fine Particle Stack Spectrometer System (FPSSS). It is a laser-fed optical system with detection by near-forward light scattering. Sample volume is established by a high-re...

  3. FIELD MEASUREMENT OF DISSOLVED OXYGEN: A COMPARISON OF METHODS

    EPA Science Inventory

    The ability to confidently measure the concentration of dissolved oxygen (D.O.) in ground water is a key aspect of remedial selection and assessment. Presented here is a comparison of the commonly practiced methods for determining D.O. concentrations in ground water, including c...

  4. 47 CFR 73.314 - Field strength measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    .... (1) Preparation for measurement. (i) The population (P) of the community, and its suburbs, if any, is determined by reference to an appropriate source, e.g., the 1970 U.S. Census tables of population of cities.... (iii) A rectangular grid, of such size and shape as to encompass the boundaries of the community...

  5. 47 CFR 73.686 - Field strength measurements.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... television service in specific communities—(1) Preparation for measurement. (i) The population (P) of the.... Census tables of population of cities and urbanized areas. (ii) The number of locations at which... product is a number greater than 15. (iii) A rectangular grid, of such size and shape as to encompass...

  6. Measurements of High-Contrast Starshade Performance in the Field

    NASA Astrophysics Data System (ADS)

    Smith, Daniel; Glassman, Tiffany M.; Warwick, Steve; Novicki, Megan; Richards, Michael; Patterson, Keith; Harness, Anthony

    2016-01-01

    The external Starshade is a method for the direct detection and spectral characterization of terrestrial planets around other stars, a key goal identified in ASTRO2010. In an effort to validate the starlight-suppression performance of the Starshade, we have measured contrast better than 1X10-9 using 60 cm Starshades at points just beyond the Starshade tips. These measurements were made over a 50% spectral bandpass, using an incoherent light source (a white LED), and in challenging outdoor test environments. Our experimental setup is designed to provide Starshade to telescope separation and telescope aperture size that are scaled as closely as possible to the flight system. The measurements confirm not only the overall starlight-suppression capability of the Starshade concept but also the robustness of the setup to optical disturbances such as atmospheric effects at the test site. The spectral coverage is limited only by the optics and detectors in our test setup, not by the Starshade itself. Here we describe our latest results as well as detailed comparisons of the measured results to model predictions. Plans and status of the next phase of ground testing are also discussed.

  7. Electric field measurement of organic photovoltaic cell model using electrooptic probe

    NASA Astrophysics Data System (ADS)

    Saito, Ryo; Yabe, Yoko; Suzuki, Akito; Shinagawa, Mitsuru; Sugino, Hiroyuki; Katsuyama, Jun; Matsumoto, Yoshinori

    2016-09-01

    In this paper, we describe the use of a transverse electrooptic probe to measure the electric field of an organic photovoltaic (OPV) cell model. It is necessary to measure the voltage of each OPV cell in order to diagnose failure of the OPV. An electric field is generated by the OPV cell voltage, so measuring the electric field is effective for obtaining a failure diagnosis of the OPV. We use a transverse electrooptic probe as an instrumentation tool for measuring the electric field over the OPV. We confirmed the principle of superposition for the electric field strength from each OPV cell model. These results show that the calibration of each OPV cell voltage can be accomplished by measuring the electric field strength over the OPV cells.

  8. Caustic-Side Solvent Extraction: Prediction of Cesium Extraction for Actual Wastes and Actual Waste Simulants

    SciTech Connect

    Delmau, L.H.; Haverlock, T.J.; Sloop, F.V., Jr.; Moyer, B.A.

    2003-02-01

    This report presents the work that followed the CSSX model development completed in FY2002. The developed cesium and potassium extraction model was based on extraction data obtained from simple aqueous media. It was tested to ensure the validity of the prediction for the cesium extraction from actual waste. Compositions of the actual tank waste were obtained from the Savannah River Site personnel and were used to prepare defined simulants and to predict cesium distribution ratios using the model. It was therefore possible to compare the cesium distribution ratios obtained from the actual waste, the simulant, and the predicted values. It was determined that the predicted values agree with the measured values for the simulants. Predicted values also agreed, with three exceptions, with measured values for the tank wastes. Discrepancies were attributed in part to the uncertainty in the cation/anion balance in the actual waste composition, but likely more so to the uncertainty in the potassium concentration in the waste, given the demonstrated large competing effect of this metal on cesium extraction. It was demonstrated that the upper limit for the potassium concentration in the feed ought to not exceed 0.05 M in order to maintain suitable cesium distribution ratios.

  9. Solar wind interaction effects on the magnetic fields around Mars: Consequences for interplanetary and crustal field measurements

    NASA Astrophysics Data System (ADS)

    Luhmann, J. G.; Ma, Y.-J.; Brain, D. A.; Ulusen, D.; Lillis, R. J.; Halekas, J. S.; Espley, J. R.

    2015-11-01

    The first unambiguous detections of the crustal remanent magnetic fields of Mars were obtained by Mars Global Surveyor (MGS) during its initial orbits around Mars, which probed altitudes to within ∼110 km of the surface. However, the majority of its measurements were carried out around 400 km altitude, fixed 2 a.m. to 2 p.m. local time, mapping orbit. While the general character and planetary origins of the localized crustal fields were clearly revealed by the mapping survey data, their effects on the solar wind interaction could not be investigated in much detail because of the limited mapping orbit sampling. Previous analyses (Brain et al., 2006) of the field measurements on the dayside nevertheless provided an idea of the extent to which the interaction of the solar wind and planetary fields leads to non-ideal field draping at the mapping altitude. In this study we use numerical simulations of the global solar wind interaction with Mars as an aid to interpreting that observed non-ideal behavior. In addition, motivated by models for different interplanetary field orientations, we investigate the effects of induced and reconnected (planetary and external) fields on the Martian field's properties derived at the MGS mapping orbit altitude. The results suggest that inference of the planetary low order moments is compromised by their influence. In particular, the intrinsic dipole contribution may differ from that in the current models because the induced component is so dominant.

  10. Clinical use of diodes and micro-chambers to obtain accurate small field output factor measurements.

    PubMed

    Kairn, T; Charles, P H; Cranmer-Sargison, G; Crowe, S B; Langton, C M; Thwaites, D I; Trapp, J V

    2015-06-01

    There have been substantial advances in small field dosimetry techniques and technologies, over the last decade, which have dramatically improved the achievable accuracy of small field dose measurements. This educational note aims to help radiation oncology medical physicists to apply some of these advances in clinical practice. The evaluation of a set of small field output factors (total scatter factors) is used to exemplify a detailed measurement and simulation procedure and as a basis for discussing the possible effects of simplifying that procedure. Field output factors were measured with an unshielded diode and a micro-ionisation chamber, at the centre of a set of square fields defined by a micro-multileaf collimator. Nominal field sizes investigated ranged from 6 × 6 to 98 × 98 mm(2). Diode measurements in fields smaller than 30 mm across were corrected using response factors calculated using Monte Carlo simulations of the diode geometry and daisy-chained to match micro-chamber measurements at intermediate field sizes. Diode measurements in fields smaller than 15 mm across were repeated twelve times over three separate measurement sessions, to evaluate the reproducibility of the radiation field size and its correspondence with the nominal field size. The five readings that contributed to each measurement on each day varied by up to 0.26  %, for the "very small" fields smaller than 15 mm, and 0.18 % for the fields larger than 15 mm. The diode response factors calculated for the unshielded diode agreed with previously published results, within uncertainties. The measured dimensions of the very small fields differed by up to 0.3 mm, across the different measurement sessions, contributing an uncertainty of up to 1.2 % to the very small field output factors. The overall uncertainties in the field output factors were 1.8 % for the very small fields and 1.1 % for the fields larger than 15 mm across. Recommended steps for acquiring small field output

  11. Savannah River Site Experiences in In Situ Field Measurements of Radioactive Materials

    SciTech Connect

    Moore, F.S.

    1999-10-07

    This paper discusses some of the field gamma-ray measurements made at the Savannah River Site, the equipment used for the measurements, and lessons learned during in situ identification and characterization of radioactive materials.

  12. Field measurement of tension in a T-142 tank track

    SciTech Connect

    Trusty, R.M.; Wilt, M.D.; Carter, G.W.; Lesuer, D.R.

    1985-04-01

    This paper describes a method used to measure the tension developed between neighboring track sections of a T-142-track mounted on an M-60 tank at the Yuma Proving Grounds. Such information is important for input to the computer models being developed for the US Army Tank-Automotive Command. A section of track was instrumented with strain gages and mounted in a tensile testing machine. The strain gage output was calibrated as a function of tension. The calibrated track section was mounted on the tank and connected through a hard-wire electrical tether to a portable data acquisition system. A video recording system with a clock common to the data acquisition system was used to correlate environmental inputs to tension data. Initial track pretension levels were measured. Data were also acquired when the tank traversed several objects, moved uphill over an obstacle, and executed pivot turns. This data has been used in the new computer models.

  13. Field-free molecular alignment for measuring ionization probability

    NASA Astrophysics Data System (ADS)

    Loriot, V.; Hertz, E.; Lavorel, B.; Faucher, O.

    2008-01-01

    We have shown in a recent letter (Loriot et al 2006 Opt. Lett. 31 2897) the possibility of determining the ionization probability of linear molecules by using an all-optical technique that takes advantage of post-pulse molecular alignment. To that end, we have implemented a 'cross-defocusing' technique producing a signal sensitive to both alignment and ionization. The analysis of the signal provides a quantitative measurement of the ionization probability calibrated with molecular alignment. In the present work, the method is discussed in more detail and applied to the measurement of the ionization probability of N2 as well as to the determination of the ionization ratio between (i) N2 and Ar and (ii) O2 and Xe. We demonstrate in addition a progress in the scheme in order to improve the accuracy at low intensity.

  14. [Measurement of chemical agents in metallurgy field: electric steel plant].

    PubMed

    Cottica, D; Grignani, E; Ghitti, R; Festa, D; Apostoli, P

    2012-01-01

    The steel industry maintains its important position in the context of the Italian production involving thousands of workers. The iron and steel processes are divided into primary steel industry, production of intermediate minerals, and secondary steel, scrap from the production of semi-finished industrial and consumer sector (metal inserted into components and metal used for dissipative uses, primarily coatings) and industrial waste. The paper presents the results of environmental monitoring carried out in some electric steel plant for the measurement of airborne chemicals that characterize the occupational exposure of workers employed in particular area like electric oven, to treatment outside the furnace, continuous casting area. For the sampling of the pollutants were used both personal and in fixed positions samplers. The pollutants measured are those typical of steel processes inhalable dust, metals, respirable dust, crystalline silica, but also Polycyclic Aromatic Hydrocarbons (PAH), polychlorinated dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs). PMID:23213795

  15. Direct Measurement of the Flow Field around Swimming Microorganisms

    NASA Astrophysics Data System (ADS)

    Drescher, Knut; Goldstein, Raymond E.; Michel, Nicolas; Polin, Marco; Tuval, Idan

    2010-10-01

    Swimming microorganisms create flows that influence their mutual interactions and modify the rheology of their suspensions. While extensively studied theoretically, these flows have not been measured in detail around any freely-swimming microorganism. We report such measurements for the microphytes Volvox carteri and Chlamydomonas reinhardtii. The minute (˜0.3%) density excess of V. carteri over water leads to a strongly dominant Stokeslet contribution, with the widely-assumed stresslet flow only a correction to the subleading source dipole term. This implies that suspensions of V. carteri have features similar to suspensions of sedimenting particles. The flow in the region around C. reinhardtii where significant hydrodynamic interaction is likely to occur differs qualitatively from a puller stresslet, and can be described by a simple three-Stokeslet model.

  16. Direct measurement of the flow field around swimming microorganisms

    NASA Astrophysics Data System (ADS)

    Polin, Marco; Drescher, Knut; Goldstein, Raymond E.; Michel, Nicolas; Tuval, Idan

    2010-11-01

    Swimming microorganisms create flows that influence their mutual interactions and modify the rheology of their suspensions. While extensively studied theoretically, these flows have not been measured in detail around any freely-swimming microorganism. We report such measurements for the microphytes Volvox carteri and Chlamydomonas reinhardtii. The minute (˜0.3%) density excess of V. carteri over water leads to a strongly dominant Stokeslet contribution, with the widely-assumed stresslet flow only a correction to the subleading source dipole term. This implies that suspensions of V. carteri have features similar to suspensions of sedimenting particles. The flow in the region around C. reinhardtii where significant hydrodynamic interaction is likely to occur differs qualitatively from a "puller" stresslet, and can be described by a simple three-Stokeslet model.

  17. Gage for measuring fluted oil field tubular members

    SciTech Connect

    Case, W.A.; Burt, J.R.

    1987-03-17

    A gage is described for measuring the nominal diameter of an elongated tubular member having circumferentially spaced apart radially outwardly extending flutes and for calibrating the amount of wear to the flutes and predicting the future wear life of the tubular member. The gage comprises: a first gage part including a pair of spaced apart colinear elongated first handlebar halves with a generally semi-circular first half ring positioned between the first handlebar halves. The first half ring includes at least one flute engaging surface which includes stepped arcuate flute engaging portions positioned at radii from the center of the first ring half corresponding to different diameters to be measured; a second gage part including a pair of spaced apart colinear elongated second handlebar halves with a generally semicircular second half ring positioned between the second handlebar halves. The second half ring includes at least one flute engaging surface which includes stepped arcuate flute engaging portions positioned a radii from the center of the second ring half corresponding to different diameters to be measured. The number of flute engaging surfaces of the first and second ring halves is equal to the number of flutes on the tubular member; and a hinge pivotally connecting together one handlebar half of the first gage part to one handlebar half of the second gage part.

  18. Field measurement of tension in a T-142 tank track

    SciTech Connect

    Trusty, R.M.; Wilt, M.D.; Carter, G.W.; Lesuer, D.R.

    1984-11-01

    This paper describes a method employed by the Engineering Measurements Section at the Lawrence Livermore National Laboratory (LLNL) to measure the tension developed between neighboring track sections of a T-142-track mounted on an M-60 tank at the Yuma Proving Grounds. Such information is important for input to the computer models that are being developed by the laboratory for the US Army Tank-Automotive Command. A section of track was instrumented with strain gages and mounted in a tensile testing machine. The strain gage output was then calibrated as a function of tension. The calibrated track section was mounted on the tank and connected through a hard-wire electrical tether to a portable data acquisition system. A video recording system with a clock common to the data acquisition system was used to correlate environmental inputs to tension data. Initial track pre-tension levles were measured. Data were also acquired when the tank traversed several objects, moved uphill over an obstacle, and executed pivot turns. This data have been used in the new computer models at LLNL.

  19. MEASUREMENTS OF HIGH-FIELD THZ INDUCED PHOTOCURRENTS IN SEMICONDUCTORS

    SciTech Connect

    Wiczer, M.; Lindenberg, A.

    2008-01-01

    THz pulses have provided a useful tool for probing the time-resolved dynamics of free carriers in a system. However, the development of methods to produce intense THz radiation has been slow. We have developed a method for producing intense ultra-short THz pulses, which have a full width at half maximum of 300 fs — approximately a half cycle of THz radiation. These intense half cycle pulses (HCPs) allowed us to use THz radiation as a source of excitation. By exposing the semiconductor indium antimonide (InSb) to intense THz HCP radiation, we have observed non-linear optical effects which suggest the generation of new free carriers by below band-gap THz photons. This generation of free carriers appears to be due to an avalanche multiplication process which then induces a current in the time-scale of our THz pulse. This amplifi cation on such a short timescale suggests the possibility of an ultrafast detector of weak above band-gap radiation. We constructed a device which detects these currents by painting an electrode structure on the surface of the semiconductor. The currents induced across the electrodes by this avalanche multiplication process were measured and compared with other measurements of this non-linear optical process. We successfully measured THz induced currents in InSb, suggesting promise towards the development of an ultra-fast detector. Further, we have gained insight into a possible physical explanation of the THz induced free carriers we observe in InSb.

  20. Comparisons of measured and calculated potential magnetic fields. [in solar corona

    NASA Technical Reports Server (NTRS)

    Hagyard, M. J.; Teuber, D.

    1978-01-01

    Photospheric line-of-sight and transverse-magnetic-field data obtained, with a vector magnetograph system for an isolated sunspot are described. A study of the linear polarization patterns and of the calculated transverse field lines indicates that the magnetic field of the region is very nearly potential. The H-alpha fibril structures of this region as seen in high-resolution photographs corroborate this conclusion. Consequently, a potential-field calculation is described using the measured line-of-sight fields together with assumed Neumann boundary conditions; both are necessary and sufficient for a unique solution. The computed transverse fields are then compared with the measured transverse fields to verify the potential-field model and assumed boundary values. The implications of these comparisons for the validity of magnetic-field extrapolations using potential theory are discussed.