Science.gov

Sample records for adcp discharge measurements

  1. Measuring discharge with ADCPs: Inferences from synthetic velocity profiles

    USGS Publications Warehouse

    Rehmann, C.R.; Mueller, D.S.; Oberg, K.A.

    2009-01-01

    Synthetic velocity profiles are used to determine guidelines for sampling discharge with acoustic Doppler current profilers (ADCPs). The analysis allows the effects of instrument characteristics, sampling parameters, and properties of the flow to be studied systematically. For mid-section measurements, the averaging time required for a single profile measurement always exceeded the 40 s usually recommended for velocity measurements, and it increased with increasing sample interval and increasing time scale of the large eddies. Similarly, simulations of transect measurements show that discharge error decreases as the number of large eddies sampled increases. The simulations allow sampling criteria that account for the physics of the flow to be developed. ?? 2009 ASCE.

  2. Use of an Acoustic Doppler Current Profiler (ADCP) to Measure Hypersaline Bidirectional Discharge

    USGS Publications Warehouse

    Johnson, K.K.; Loving, B.L.

    2002-01-01

    The U.S. Geological Survey measures the exchange of flow between the north and south parts of Great Salt Lake, Utah, as part of a monitoring program. Turbidity and bidirectional flow through the breach in the causeway that divides the lake into two parts makes it difficult to measure discharge with conventional streamflow techniques. An acoustic Doppler current profiler (ADCP) can be used to more accurately define the angles of flow and the location of the interface between the layers of flow. Because of the high salinity levels measured in Great Salt Lake (60-280 parts per thousand), special methods had to be developed to adjust ADCP-computed discharges for the increased speed of sound in hypersaline waters and for water entrained at the interface between flow layers.

  3. Field intercomparison of channel master ADCP with RiverSonde Radar for measuring river discharge

    USGS Publications Warehouse

    Spain, P.; Marsden, R.; Barrick, D.; Teague, C.; Ruhl, C.

    2005-01-01

    The RiverSonde radar makes non-contact measurement of a horizontal swath of surface velocity across a river section. This radar, which has worked successfully at several rivers in the Western USA, has shown encouraging correlation with simultaneous measurements of average currents at one level recorded by an acoustic travel-time system. This work reports a field study intercomparing data sets from a 600 kHz Channel Master ADCP with the RiverSonde radar. The primary goal was to begin to explore the robustness of the radar data as a reliable index of discharge. This site Is at Three Mile Slough in Northern California, USA. The larger intent of the work is to examine variability in space and time of the radar's surface currents compared with subsurface flows across the river section. Here we examine data from a couple of periods with strong winds. ?? 2005 IEEE.

  4. In Search of Easy-to-Use Methods for Calibrating ADCP's for Velocity and Discharge Measurements

    USGS Publications Warehouse

    Oberg, K.

    2002-01-01

    A cost-effective procedure for calibrating acoustic Doppler current profilers (ADCP) in the field was presented. The advantages and disadvantages of various methods which are used for calibrating ADCP were discussed. The proposed method requires the use of differential global positioning system (DGPS) with sub-meter accuracy and standard software for collecting ADCP data. The method involves traversing a long (400-800 meter) course at a constant compass heading and speed, while collecting simultaneous DGPS and ADCP data.

  5. Evaluation of mean velocity and turbulence measurements with ADCPs

    USGS Publications Warehouse

    Nystrom, E.A.; Rehmann, C.R.; Oberg, K.A.

    2007-01-01

    To test the ability of acoustic Doppler current profilers (ADCPs) to measure turbulence, profiles measured with two pulse-to-pulse coherent ADCPs in a laboratory flume were compared to profiles measured with an acoustic Doppler velocimeter, and time series measured in the acoustic beam of the ADCPs were examined. A four-beam ADCP was used at a downstream station, while a three-beam ADCP was used at a downstream station and an upstream station. At the downstream station, where the turbulence intensity was low, both ADCPs reproduced the mean velocity profile well away from the flume boundaries; errors near the boundaries were due to transducer ringing, flow disturbance, and sidelobe interference. At the upstream station, where the turbulence intensity was higher, errors in the mean velocity were large. The four-beam ADCP measured the Reynolds stress profile accurately away from the bottom boundary, and these measurements can be used to estimate shear velocity. Estimates of Reynolds stress with a three-beam ADCP and turbulent kinetic energy with both ADCPs cannot be computed without further assumptions, and they are affected by flow inhomogeneity. Neither ADCP measured integral time scales to within 60%. ?? 2007 ASCE.

  6. Effect of temporal resolution on the accuracy of ADCP measurements

    USGS Publications Warehouse

    Gonzalez-Castro, J. A.; Oberg, K.; Duncker, J.J.

    2004-01-01

    velocity fluctuations and is used to evaluate the mean-square error as a function of the integration time. The implications of these errors in typical ADCP measurements for discharge estimates in natural streams are discussed. Copyright ASCE 2004.

  7. Use of an ADCP to compute suspended-sediment discharge in the tidal Hudson River, New York

    USGS Publications Warehouse

    Wall, Gary R.; Nystrom, Elizabeth A.; Litten, Simon

    2006-01-01

    Acoustic Doppler current profilers (ADCPs) can provide data needed for computation of suspended-sediment discharge in complex river systems, such as tidal rivers, in which conventional methods of collecting time-series data on suspended-sediment concentration (SSC) and water discharge are not feasible. Although ADCPs are not designed to measure SSC, ADCP data can be used as a surrogate under certain environmental conditions. However, the software for such computation is limited, and considerable post-processing is needed to correct and normalize ADCP data for this use. This report documents the sampling design and computational procedure used to calibrate ADCP measures of echo intensity to SSC and water velocity to discharge in the computation of suspended-sediment discharge at the study site on the Hudson River near Poughkeepsie, New York. The methods and procedures described may prove useful to others doing similar work in different locations; however, they are specific to this study site and may have limited applicability elsewhere.

  8. Geochemistry of Amazon Basin supported by the ADCP measurements

    NASA Astrophysics Data System (ADS)

    Paca, Victor; Moreira, Daniel; Monteiro, Achiles; Roig, Henrique

    2014-05-01

    The Amazon River is the largest river in the world in volume of water. The basin has 6.915.000 Km2, but the last gauging station of Amazon River with regular and continuous measurements of discharge and sediment transport are Óbidos station with 4.670.000 Km2. Óbidos It is also the last stream gauge station with no or less tidal effect observed from Atlantic Ocean and registered. The Clim-Amazon Project has been done the first measurements with the purpose to acquire geochemical and hydrological informations downstream Óbidos station. The system studied has input data of sediments load after Óbidos, and the output of the system, at the Amazon River is at Macapá, close to the mouth of Amazon river. And flow the main tributaries along this way, between these two stations. To evaluate the geochemical source, the mass balance, and isotopic geochemistry is necessary the informations about the traces the main chemical elements, transported by the discharge from the main rivers of this area: Tapajos, Xingu, Paru, Jari, and the Amazon River at Monte Alegre and at Macapá. The ADCP - Acoustic Doppler Current Profile, equipment is used to get the stream discharge value at the moment of transect. But also get two more informations necessary for the geochemistry, and do the collecting points profiles. The place with most velocity at transect or the place with more backscatter. These informations are related with the sediment load of the river. Or which one can provide the better idea of how are transported the sediments at the measured transects. What was to observe was the main speed of the stream flow or the main backscatter sectional. The main purpose of the work is to show how works the correlation between the backscatter and speed data given by the ADCP, downstream Óbidos, and the main confluences of Amazon River, until Macapá. The ADCP measurements support the geochemical studies and the course of sediments load transported by the discharge of these rivers.

  9. Development of Topological Correction Algorithms for ADCP Multibeam Bathymetry Measurements

    NASA Astrophysics Data System (ADS)

    Yang, Sung-Kee; Kim, Dong-Su; Kim, Soo-Jeong; Jung, Woo-Yul

    2013-04-01

    Acoustic Doppler Current Profilers (ADCPs) are increasingly popular in the river research and management communities being primarily used for estimation of stream flows. ADCPs capabilities, however, entail additional features that are not fully explored, such as morphologic representation of river or reservoir bed based upon multi-beam depth measurements. In addition to flow velocity, ADCP measurements include river bathymetry information through the depth measurements acquired in individual 4 or 5 beams with a given oblique angle. Such sounding capability indicates that multi-beam ADCPs can be utilized as an efficient depth-sounder to be more capable than the conventional single-beam eco-sounders. The paper introduces the post-processing algorithms required to deal with raw ADCP bathymetry measurements including the following aspects: a) correcting the individual beam depths for tilt (pitch and roll); b) filtering outliers using SMART filters; d) transforming the corrected depths into geographical coordinates by UTM conversion; and, e) tag the beam detecting locations with the concurrent GPS information; f) spatial representation in a GIS package. The developed algorithms are applied for the ADCP bathymetric dataset acquired from Han-Cheon in Juju Island to validate their applicability.

  10. Velocity Mapping Toolbox (VMT): a processing and visualization suite for moving-vessel ADCP measurements

    USGS Publications Warehouse

    Parsons, D.R.; Jackson, P.R.; Czuba, J.A.; Engel, F.L.; Rhoads, B.L.; Oberg, K.A.; Best, J.L.; Mueller, D.S.; Johnson, K.K.; Riley, J.D.

    2013-01-01

    The use of acoustic Doppler current profilers (ADCP) for discharge measurements and three-dimensional flow mapping has increased rapidly in recent years and has been primarily driven by advances in acoustic technology and signal processing. Recent research has developed a variety of methods for processing data obtained from a range of ADCP deployments and this paper builds on this progress by describing new software for processing and visualizing ADCP data collected along transects in rivers or other bodies of water. The new utility, the Velocity Mapping Toolbox (VMT), allows rapid processing (vector rotation, projection, averaging and smoothing), visualization (planform and cross-section vector and contouring), and analysis of a range of ADCP-derived datasets. The paper documents the data processing routines in the toolbox and presents a set of diverse examples that demonstrate its capabilities. The toolbox is applicable to the analysis of ADCP data collected in a wide range of aquatic environments and is made available as open-source code along with this publication.

  11. Single-ping ADCP measurements in the Strait of Gibraltar

    NASA Astrophysics Data System (ADS)

    Sammartino, Simone; García Lafuente, Jesús; Naranjo, Cristina; Sánchez Garrido, José Carlos; Sánchez Leal, Ricardo

    2016-04-01

    In most Acoustic Doppler Current Profiler (ADCP) user manuals, it is widely recommended to apply ensemble averaging of the single-pings measurements, in order to obtain reliable observations of the current speed. The random error related to the single-ping measurement is typically too high to be used directly, while the averaging operation reduces the ensemble error of a factor of approximately √N, with N the number of averaged pings. A 75 kHz ADCP moored in the western exit of the Strait of Gibraltar, included in the long-term monitoring of the Mediterranean outflow, has recently served as test setup for a different approach to current measurements. The ensemble averaging has been disabled, while maintaining the internal coordinate conversion made by the instrument, and a series of single-ping measurements has been collected every 36 seconds during a period of approximately 5 months. The huge amount of data has been fluently handled by the instrument, and no abnormal battery consumption has been recorded. On the other hand a long and unique series of very high frequency current measurements has been collected. Results of this novel approach have been exploited in a dual way: from a statistical point of view, the availability of single-ping measurements allows a real estimate of the (a posteriori) ensemble average error of both current and ancillary variables. While the theoretical random error for horizontal velocity is estimated a priori as ˜2 cm s‑1 for a 50 pings ensemble, the value obtained by the a posteriori averaging is ˜15 cm s‑1, with an asymptotical behavior starting from an averaging size of 10 pings per ensemble. This result suggests the presence of external sources of random error (e.g.: turbulence), of higher magnitude than the internal sources (ADCP intrinsic precision), which cannot be reduced by the ensemble averaging. On the other hand, although the instrumental configuration is clearly not suitable for a precise estimation of turbulent

  12. 3-D flow and scour near a submerged wing dike: ADCP measurements on the Missouri River

    USGS Publications Warehouse

    Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

    2011-01-01

    Detailed mapping of bathymetry and three-dimensional water velocities using a boat-mounted single-beam sonar and acoustic Doppler current profiler (ADCP) was carried out in the vicinity of two submerged wing dikes located in the Lower Missouri River near Columbia, Missouri. During high spring flows the wing dikes become submerged, creating a unique combination of vertical flow separation and overtopping (plunging) flow conditions, causing large-scale three-dimensional turbulent flow structures to form. On three different days and for a range of discharges, sampling transects at 5 and 20 m spacing were completed, covering the area adjacent to and upstream and downstream from two different wing dikes. The objectives of this research are to evaluate whether an ADCP can identify and measure large-scale flow features such as recirculating flow and vortex shedding that develop in the vicinity of a submerged wing dike; and whether or not moving-boat (single-transect) data are sufficient for resolving complex three-dimensional flow fields. Results indicate that spatial averaging from multiple nearby single transects may be more representative of an inherently complex (temporally and spatially variable) three-dimensional flow field than repeated single transects. Results also indicate a correspondence between the location of calculated vortex cores (resolved from the interpolated three-dimensional flow field) and the nearby scour holes, providing new insight into the connections between vertically oriented coherent structures and local scour, with the unique perspective of flow and morphology in a large river.

  13. Inner Shelf Current Structure Under Different Forcing Mechanisms— Combining ADCP and HF Radar Measurements

    NASA Astrophysics Data System (ADS)

    Kastner, S.; Kirincich, A.; Lentz, S. J.

    2014-12-01

    Our understanding of wind and wave driven currents in the coastal ocean has been limited by our inability to measure currents within a few meters of the surface. To improve our understanding of current dynamics in the upper few meters of the ocean we combine 8 months of ADCP measurements from the Martha's Vineyard Coastal Observatory with high-frequency (HF) radar measurements of surface currents. These techniques compliment each other, as the HF radar can only observe the surface velocities, and the ADCP cannot take accurate measurements in the upper few meters of the water column. We find that currents can vary significantly over the upper two meters of the inner shelf. Extrapolations to the surface based on the ADCP data are inconsistent with that observed by the HF radar. When different types of forcing conditions were examined, it was found that this difference is most evident in cases when wind stresses are weak (ADCP observations. Models indicate this difference can be attributed in part to Stokes' drift, measured by the HF radar but not the ADCP. When the ADCP velocities are corrected for Stokes' drift, the difference between the HF radar surface current and the top ADCP current is consistent with a simple model of near-surface wind-driven current shear. This suggests future attempts to extrapolate ADCP currents toward the surface should consider wind-driven shear. This result can be used to more accurately estimate onshore transport, which has applications in calculating nutrient and pollutant transport.

  14. ADCP measurements of gravity currents in the Chicago River, Illinois

    USGS Publications Warehouse

    Garcia, C.M.; Oberg, K.; Garcia, M.H.

    2007-01-01

    A unique set of observations of stratified flow phenomena in the Chicago River was made using an upward-looking acoustic Doppler current profiler (ADCP) during the period November 20, 2003 to February 1, 2004. Water density differences between the Chicago River and its North Branch (NB) seem to be responsible for the development of gravity currents. With the objective of characterizing the occurrence, frequency, and evolution of such currents, the ADCP was configured to continuously collect high-resolution water velocity and echo intensity profiles in the Chicago River at Columbus Drive. During the observation period, 28 gravity current events were identified, lasting a total of 77% of the time. Sixteen of these events were generated by underflows from the NB and 12 of these events were generated by overflows from the NB. On average, the duration of the underflow and overflow events was 52.3 and 42.1 h, respectively. A detailed analysis of one underflow event, which started on January 7, 2004, and lasted about 65h, was performed. This is the first time that ADCP technology has been used to continuously monitor gravity currents in a river. ?? 2007 ASCE.

  15. 3-D flow and scour near a submerged wing dike: ADCP measurements on the Missouri River

    USGS Publications Warehouse

    Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

    2011-01-01

    Detailed mapping of bathymetry and three-dimensional water velocities using a boat-mounted single-beam sonar and acoustic Doppler current profiler (ADCP) was carried out in the vicinity of two submerged wing dikes located in the Lower Missouri River near Columbia, Missouri. During high spring flows the wing dikes become submerged, creating a unique combination of vertical flow separation and overtopping (plunging) flow conditions, causing large-scale three-dimensional turbulent flow structures to form. On three different days and for a range of discharges, sampling transects at 5 and 20 m spacing were completed, covering the area adjacent to and upstream and downstream from two different wing dikes. The objectives of this research are to evaluate whether an ADCP can identify and measure large-scale flow features such as recirculating flow and vortex shedding that develop in the vicinity of a submerged wing dike; and whether or not moving-boat (single-transect) data are sufficient for resolving complex three-dimensional flow fields. Results indicate that spatial averaging from multiple nearby single transects may be more representative of an inherently complex (temporally and spatially variable) three-dimensional flow field than repeated single transects. Results also indicate a correspondence between the location of calculated vortex cores (resolved from the interpolated three-dimensional flow field) and the nearby scour holes, providing new insight into the connections between vertically oriented coherent structures and local scour, with the unique perspective of flow and morphology in a large river. Copyright 2011 by the American Geophysical Union.

  16. extrap: Software to assist the selection of extrapolation methods for moving-boat ADCP streamflow measurements

    USGS Publications Warehouse

    Mueller, David S.

    2013-01-01

    profiles from the entire cross section and multiple transects to determine a mean profile for the measurement. The use of an exponent derived from normalized data from the entire cross section is shown to be valid for application of the power velocity distribution law in the computation of the unmeasured discharge in a cross section. Selected statistics are combined with empirically derived criteria to automatically select the appropriate extrapolation methods. A graphical user interface (GUI) provides the user tools to visually evaluate the automatically selected extrapolation methods and manually change them, as necessary. The sensitivity of the total discharge to available extrapolation methods is presented in the GUI. Use of extrap by field hydrographers has demonstrated that extrap is a more accurate and efficient method of determining the appropriate extrapolation methods compared with tools currently (2012) provided in the ADCP manufacturers’ software.

  17. Use of Acoustic Doppler Instruments for Measuring Discharge in Streams with Appreciable Sediment Transport

    USGS Publications Warehouse

    Mueller, D.S.

    2002-01-01

    The use of Acoustic Doppler current profilers (ADCP) for measuring discharge in streams with sediment transport was discussed. The studies show that the acoustic frequency of an ADCP in combination with the sediment transport characteristics in a river causes the ADCP bottom-tracking algorithms to detect a moving bottom. A moving bottom causes bottom-tracking-referenced water velocities and discharges to be biased low. The results also show that the use of differential global positioning system (DGPS) data allows accurate measurement of water velocities and discharges in such cases.

  18. Discharge measurements using a broad-band acoustic Doppler current profiler

    USGS Publications Warehouse

    Simpson, Michael R.

    2002-01-01

    The measurement of unsteady or tidally affected flow has been a problem faced by hydrologists for many years. Dynamic discharge conditions impose an unreasonably short time constraint on conventional current-meter discharge-measurement methods, which typically last a minimum of 1 hour. Tidally affected discharge can change more than 100 percent during a 10-minute period. Over the years, the U.S. Geological Survey (USGS) has developed moving-boat discharge-measurement techniques that are much faster but less accurate than conventional methods. For a bibliography of conventional moving-boat publications, see Simpson and Oltmann (1993, page 17). The advent of the acoustic Doppler current profiler (ADCP) made possible the development of a discharge-measurement system capable of more accurately measuring unsteady or tidally affected flow. In most cases, an ADCP discharge-measurement system is dramatically faster than conventional discharge-measurement systems, and has comparable or better accuracy. In many cases, an ADCP discharge-measurement system is the only choice for use at a particular measurement site. ADCP systems are not yet ?turnkey;? they are still under development, and for proper operation, require a significant amount of operator training. Not only must the operator have a rudimentary knowledge of acoustic physics, but also a working knowledge of ADCP operation, the manufacturer's discharge-measurement software, and boating techniques and safety.

  19. Measuring discharge with acoustic Doppler current profilers from a moving boat

    USGS Publications Warehouse

    Mueller, David S.; Wagner, Chad R.; Rehmel, Michael S.; Oberg, Kevin A.; Rainville, Francois

    2013-01-01

    The use of acoustic Doppler current profilers (ADCPs) from a moving boat is now a commonly used method for measuring streamflow. The technology and methods for making ADCP-based discharge measurements are different from the technology and methods used to make traditional discharge measurements with mechanical meters. Although the ADCP is a valuable tool for measuring streamflow, it is only accurate when used with appropriate techniques. This report presents guidance on the use of ADCPs for measuring streamflow; this guidance is based on the experience of U.S. Geological Survey employees and published reports, papers, and memorandums of the U.S. Geological Survey. The guidance is presented in a logical progression, from predeployment planning, to field data collection, and finally to post processing of the collected data. Acoustic Doppler technology and the instruments currently (2013) available also are discussed to highlight the advantages and limitations of the technology. More in-depth, technical explanations of how an ADCP measures streamflow and what to do when measuring in moving-bed conditions are presented in the appendixes. ADCP users need to know the proper procedures for measuring discharge from a moving boat and why those procedures are required, so that when the user encounters unusual field conditions, the procedures can be adapted without sacrificing the accuracy of the streamflow-measurement data.

  20. Using a 1200 kHz workhorse ADCP with mode 12 to measure near bottom mean currents

    USGS Publications Warehouse

    Martini, M.

    2003-01-01

    Using high frequency Acoustic Doppler Current (ADCP) profiling technology, it is possible to make high-resolution measurements of mean current profiles within a few meters of the seabed. In coastal applications, mean current speeds may be 10 cm/s or less, and oscillatory wave currents may exceed 100 cm/s during storm events. To resolve mean flows of 10 cm/s or less under these conditions, accuracies of 1 cm/s or better are desirable.

  1. Evaluation of Acoustic Doppler Current Profiler to Measure Discharge at New York Power Authority's Niagara Power Project, Niagara Falls, New York

    USGS Publications Warehouse

    Zajd, Henry J., Jr.

    2007-01-01

    The need for accurate real-time discharge in the International Niagara River hydro power system requires reliable, accurate and reproducible data. The U.S. Geological Survey has been widely using Acoustic Doppler Current Profilers (ADCP) to accurately measure discharge in riverine channels since the mid-1990s. The use of the ADCP to measure discharge has remained largely untested at hydroelectric-generation facilities such as the New York Power Authority's (NYPA) Niagara Power Project in Niagara Falls, N.Y. This facility has a large, engineered diversion channel with the capacity of high volume discharges in excess of 100,000 cubic feet per second (ft3/s). Facilities such as this could benefit from the use of an ADCP, if the ADCP discharge measurements prove to be more time effective and accurate than those obtained from the flow-calculation techniques that are currently used. Measurements of diversion flow by an ADCP in the 'Pant Leg' diversion channel at the Niagara Power Project were made on November 6, 7, and 8, 2006, and compared favorably (within 1 percent) with those obtained concurrently by a conventional Price-AA current-meter measurement during one of the ADCP measurement sessions. The mean discharge recorded during each 2-hour individual ADCP measurement session compared favorably with (3.5 to 6.8 percent greater than) the discharge values computed by the flow-calculation method presently in use by NYPA. The use of ADCP technology to measure discharge could ultimately permit increased power-generation efficiency at the NYPA Niagara Falls Power Project by providing improved predictions of the amount of water (and thus the power output) available.

  2. Quality assurance plan for discharge measurements using broadband acoustic Doppler current profilers

    USGS Publications Warehouse

    Lipscomb, S.W.

    1995-01-01

    The recent introduction of the Acoustic Doppler Current Profiler (ADCP) as an instrument for measuring velocities and discharge in the riverine and estuarine environment promises to revolutionize the way these data are collected by the U.S. Geological Survey. The ADCP and associated software, however, compose a complex system and should be used only by qualifies personnel. Standard procedures should be rigorously followed to ensure that the quality of data collected is commensurate with the standards set by the Water Resources Division for all its varied activities in hydrologic investigations.

  3. Measuring the uncertainties of discharge measurements: interlaboratory experiments in hydrometry

    NASA Astrophysics Data System (ADS)

    Le Coz, Jérôme; Blanquart, Bertrand; Pobanz, Karine; Dramais, Guillaume; Pierrefeu, Gilles; Hauet, Alexandre; Despax, Aurélien

    2015-04-01

    Quantifying the uncertainty of streamflow data is key for hydrological sciences. The conventional uncertainty analysis based on error propagation techniques is restricted by the absence of traceable discharge standards and by the weight of difficult-to-predict errors related to the operator, procedure and measurement environment. Field interlaboratory experiments recently emerged as an efficient, standardized method to 'measure' the uncertainties of a given streamgauging technique in given measurement conditions. Both uncertainty approaches are compatible and should be developed jointly in the field of hydrometry. In the recent years, several interlaboratory experiments have been reported by different hydrological services. They involved different streamgauging techniques, including acoustic profilers (ADCP), current-meters and handheld radars (SVR). Uncertainty analysis was not always their primary goal: most often, testing the proficiency and homogeneity of instruments, makes and models, procedures and operators was the original motivation. When interlaboratory experiments are processed for uncertainty analysis, once outliers have been discarded all participants are assumed to be equally skilled and to apply the same streamgauging technique in equivalent conditions. A universal requirement is that all participants simultaneously measure the same discharge, which shall be kept constant within negligible variations. To our best knowledge, we were the first to apply the interlaboratory method for computing the uncertainties of streamgauging techniques, according to the authoritative international documents (ISO standards). Several specific issues arise due to the measurements conditions in outdoor canals and rivers. The main limitation is that the best available river discharge references are usually too uncertain to quantify the bias of the streamgauging technique, i.e. the systematic errors that are common to all participants in the experiment. A reference or a

  4. TOLEX-ADCP monitoring

    NASA Astrophysics Data System (ADS)

    Hanawa, Kimio; Yoshikawa, Yasushi; Taneda, Takeshi

    Since February 1991, the Physical Oceanography Group, Tohoku University has conducted a program to monitor the oceanic current field across the Kuroshio over the Izu Ridge, south of Japan, using the Acoustic Doppler Current Profiler (ADCP) system installed on the ferry Ogasawara Maru. This ferry shuttles 58 times in a usual year between Tokyo and Chichijima in the Ogasawara (Bonin) Islands. This ADCP monitoring is regarded as one component of the Tokyo-Ogasawara Line Experiment (TOLEX). In this paper, we will briefly describe our ADCP system and data processing procedures, and will present several aspects of the current fields using the data obtained through January 1996. During the period, the Kuroshio took the bimodal paths of 34°N and 32°30‧N as mean positions on the ship course. In the sea south of the Kuroshio, many cyclonic and anticyclonic eddies with a scale of 200-400 km in diameter were observed with passing time of two-four months.

  5. Acoustic backscatter measurements with a 153 kHz ADCP in the northeastern Gulf of Mexico: determination of dominant zooplankton and micronekton scatterers

    NASA Astrophysics Data System (ADS)

    Ressler, Patrick H.

    2002-11-01

    A 153 kHz narrowband acoustic Doppler current profiler (ADCP) was used to measure volume backscattering strength ( Sv) during a deepwater oceanographic survey of cetacean and seabird habitat in the northeastern Gulf of Mexico. Sv was positively related to zooplankton and micronekton biomass (wet displacement volume) in 'sea-truth' net hauls made with a 1 m 2 Multiple Opening-Closing Net Environmental Sensing System (MOCNESS). A subset of these MOCNESS tows was used to explore the relationship between the numerical densities of various taxonomic categories of zooplankton and the ADCP backscatter signal. Crustaceans, small fish, and fragments of non-gas-bearing siphonophores in the net samples all showed significant, positive correlations with the acoustic signal, while other types of gelatinous zooplankton, pteropod and atlantid molluscs, and gas-filled siphonophore floats showed no significant correlation with Sv. Previously published acoustic scattering models for zooplankton were used to calculate expected scattering for several general zooplankton types and sizes for comparison with the field data. Even though gelatinous material often made up a large fraction of the total biomass, crustaceans, small fish, and pteropods were most likely the important scatterers. Since only crustacean and small fish densities were significantly correlated with Sv, it is suggested that Sv at 153 kHz can be used as a relative proxy for the abundance of these organisms in the Gulf of Mexico.

  6. Stream Discharge Measurements From Cableways

    USGS Publications Warehouse

    Nolan, K. Michael; Sultz, Lucky

    2000-01-01

    Cableways have been used for decades as a platform for making stream discharge measurements. Use of cableways eliminates the need to expose personnel to hazards associated with working from highway bridges. In addition, cableways allow sites to be selected that offer the best possible hydraulic characteristics for measuring stream discharge. This training presentation describes methods currently used by the U.S. Geological Survey to make stream discharge measurements from cableways.

  7. Role of turbulence fluctuations on uncertainties of acoutic Doppler current profiler discharge measurements

    USGS Publications Warehouse

    Tarrab, Leticia; Garcia, Carlos M.; Cantero, Mariano I.; Oberg, Kevin

    2012-01-01

    This work presents a systematic analysis quantifying the role of the presence of turbulence fluctuations on uncertainties (random errors) of acoustic Doppler current profiler (ADCP) discharge measurements from moving platforms. Data sets of three-dimensional flow velocities with high temporal and spatial resolution were generated from direct numerical simulation (DNS) of turbulent open channel flow. Dimensionless functions relating parameters quantifying the uncertainty in discharge measurements due to flow turbulence (relative variance and relative maximum random error) to sampling configuration were developed from the DNS simulations and then validated with field-scale discharge measurements. The validated functions were used to evaluate the role of the presence of flow turbulence fluctuations on uncertainties in ADCP discharge measurements. The results of this work indicate that random errors due to the flow turbulence are significant when: (a) a low number of transects is used for a discharge measurement, and (b) measurements are made in shallow rivers using high boat velocity (short time for the boat to cross a flow turbulence structure).

  8. Brazil current eddy activity near cape São Tomé based on direct ADCP data measurements from 2006 to 2012

    NASA Astrophysics Data System (ADS)

    Lima, N. D.; Gabioux, M.; Guerra, L. D.; Paiva, A. M.

    2013-05-01

    Cape São Tomé, in the Campos Basin, is a region of intense ocean mesoscale activity where meanders and eddies are formed by instability processes of the Brazil Current. In this work seven years of ADCP current data (2006-2012) are analyzed at different depths over the continental shelf and slope of Campos Basin in order to characterize the variability and vertical struture of meanders and eddies. The present study is a continuation of Lima et al. (2010), in which two years of current meter data, taken at fewer locations and spanning a shorter depth range, were analyzed. This preliminary study suggested that eddy formation at Cape São Tomé may occur throughout the year, and that these eddies, which present a mixed barotropic and baroclinic structure, exert significant influence on the Brazil Current and on the upper portion of the Intermediate Western Boundary Current, which flows northward at intermediate depths. The longer time series of data, now available, alow us to check the validity of Lima et al. (2010) results about mesoscale activity activity, and to test their proposed conceptual model of eddy formation for other events. The ten ADCP moorings analyzed were located between 21°S and 23°S, and 41°W and 39°W. Measurements were taken from the surface down to 750 and 900 meters, and the data have different record lengths for each mooring. High Resolution Sea Surface Temperature dates (GHRSST) are also analyzed in order to provide a broader spatial view, assisting in the interpretation of the phenomena observed in the velocity data. The new results corroborate the study of Lima et al. (2010), showing that eddy formation is a reccuring phenomenon at Cape São Tomé for all the period analyzed. Eddies generate significant variability in current velocity both at the surface and at intermediate depths, changing the depth and intensity of Brasil Current - Intermediate Western Boundary Current system. While the average current system showed a strong baroclinic

  9. Application of the loop method for correcting acoustic doppler current profiler discharge measurements biased by sediment transport

    USGS Publications Warehouse

    Mueller, David S.; Wagner, Chad R.

    2006-01-01

    A systematic bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) is attributed to the movement of sediment near the streambed-an issue widely acknowledged by the scientific community. This systematic bias leads to an underestimation of measured velocity and discharge. The integration of a differentially corrected Global Positioning System (DGPS) to track the movement of the ADCP can be used to avoid the systematic bias associated with a moving bed. DGPS systems, however, cannot provide consistently accurate positions because of multipath errors and satellite signal reception problems on waterways with dense tree canopy along the banks, in deep valleys or canyons, and near bridges. An alternative method of correcting for the moving-bed bias was investigated by the U.S. Geological Survey.

  10. Correcting acoustic Doppler current profiler discharge measurements biased by sediment transport

    USGS Publications Warehouse

    Mueller, D.S.; Wagner, C.R.

    2007-01-01

    A negative bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) is attributed to the movement of sediment on or near the streambed, and is an issue widely acknowledged by the scientific community. The integration of a differentially corrected global positioning system (DGPS) to track the movement of the ADCP can be used to avoid the systematic bias associated with a moving bed. DGPS, however, cannot provide consistently accurate positions because of multipath errors and satellite signal reception problems on waterways with dense tree canopy along the banks, in deep valleys or canyons, and near bridges. An alternative method of correcting for the moving-bed bias, based on the closure error resulting from a two-way crossing of the river, is presented. The uncertainty in the mean moving-bed velocity measured by the loop method is shown to be approximately 0.6cm/s. For the 13 field measurements presented, the loop method resulted in corrected discharges that were within 5% of discharges measured utilizing DGPS to compensate for moving-bed conditions. ?? 2007 ASCE.

  11. Discharge measurements at gaging stations

    USGS Publications Warehouse

    Turnipseed, D. Phil; Sauer, Vernon B.

    2010-01-01

    The techniques and standards for making discharge measurements at streamflow gaging stations are described in this publication. The vertical axis rotating-element current meter, principally the Price current meter, has been traditionally used for most measurements of discharge; however, advancements in acoustic technology have led to important developments in the use of acoustic Doppler current profilers, acoustic Doppler velocimeters, and other emerging technologies for the measurement of discharge. These new instruments, based on acoustic Doppler theory, have the advantage of no moving parts, and in the case of the acoustic Doppler current profiler, quickly and easily provide three-dimensional stream-velocity profile data through much of the vertical water column. For much of the discussion of acoustic Doppler current profiler moving-boat methodology, the reader is referred to U.S. Geological Survey Techniques and Methods 3-A22 (Mueller and Wagner, 2009). Personal digital assistants (PDAs), electronic field notebooks, and other personal computers provide fast and efficient data-collection methods that are more error-free than traditional hand methods. The use of portable weirs and flumes, floats, volumetric tanks, indirect methods, and tracers in measuring discharge are briefly described.

  12. Comparison of bottom-track to global positioning system referenced discharges measured using an acoustic Doppler current profiler

    USGS Publications Warehouse

    Wagner, C.R.; Mueller, D.S.

    2011-01-01

    A negative bias in discharge measurements made with an acoustic Doppler current profiler (ADCP) can be caused by the movement of sediment on or near the streambed. The integration of a global positioning system (GPS) to track the movement of the ADCP can be used to avoid the systematic negative bias associated with a moving streambed. More than 500 discharge transects from 63 discharge measurements with GPS data were collected at sites throughout the US, Canada, and New Zealand with no moving bed to compare GPS and bottom-track-referenced discharges. Although the data indicated some statistical bias depending on site conditions and type of GPS data used, these biases were typically about 0.5% or less. An assessment of differential correction sources was limited by a lack of data collected in a range of different correction sources and different GPS receivers at the same sites. Despite this limitation, the data indicate that the use of Wide Area Augmentation System (WAAS) corrected positional data is acceptable for discharge measurements using GGA as the boat-velocity reference. The discharge data based on GPS-referenced boat velocities from the VTG data string, which does not require differential correction, were comparable to the discharges based on GPS-referenced boat velocities from the differentially-corrected GGA data string. Spatial variability of measure discharges referenced to GGA, VTG and bottom-tracking is higher near the channel banks. The spatial variability of VTG-referenced discharges is correlated with the spatial distribution of maximum Horizontal Dilution of Precision (HDOP) values and the spatial variability of GGA-referenced discharges is correlated with proximity to channel banks. ?? 2011 Published by Elsevier B.V.

  13. ORNL ADCP POST-PROCESSING GUIDE AND MATLAB ALGORITHMS FOR MHK SITE FLOW AND TURBULENCE ANALYSIS

    SciTech Connect

    Gunawan, Budi; Neary, Vincent S

    2011-09-01

    Standard methods, along with guidance for post-processing the ADCP stationary measurements using MATLAB algorithms that were evaluated and tested by Oak Ridge National Laboratory (ORNL), are presented following an overview of the ADCP operating principles, deployment methods, error sources and recommended protocols for removing and replacing spurious data.

  14. Acoustic Doppler discharge-measurement system

    USGS Publications Warehouse

    Simpson, Michael R.; Oltmann, Richard N.

    1990-01-01

    A discharge-measurement system that uses a vessel-mounted acoustic Doppler current profiler has been developed and tested by the U.S. Geological Survey. Discharge measurements using the system require a fraction of the time needed for conventional current-meter discharge measurements and do not require shore-based navigational aids or tag lines for positioning the vessel.

  15. Flood discharge measurement of mountain rivers

    NASA Astrophysics Data System (ADS)

    Chen, Y.-C.

    2012-11-01

    An efficient method that accounts for personal safety, accuracy and reliability for measuring flood discharge of mountain rivers is proposed. It is composed of new measurement method, tools, and techniques. Measuring flood discharge from mountain rivers by using conventional method is costly, time-consuming, and dangerous. Thus previous discharge measurements for mountainous areas were typically based on estimated precipitation, which alone cannot generate accurate measurements. This study applies a novel flood discharge measurement system composed of an Acoustic Doppler Profiler and crane system to accurately and quickly measure velocity distributions and water depths. Moreover a novel and efficient method for measuring discharge, which is based on the relationship between mean and maximum velocities and the relationship between cross-sectional area and gauge height is applied to estimate flood discharge. Flood discharge from mountain rivers can be estimated easily and rapidly by measuring maximum velocity in the river crosssection and the gauge height. The measured flood discharges can be utilized to create a reliable stage-discharge relationship for continuous estimations of discharge using records of water stage. The proposed method was applied to the Nanshih River, Taiwan. Results of measured discharges and estimated discharges only slightly differed from each other, demonstrating the efficiency and accuracy of the proposed method.

  16. Measurement of Stream Discharge by Wading

    USGS Publications Warehouse

    Nolan, K. Michael; Shields, Ronald R.

    2000-01-01

    Most years the U.S. Geological Survey (USGS) makes over 50,000 stream discharge measurements. Over 75 percent of those measurements are made by wading streams and using the velocity-area method. This PowerPoint presentation describes how stream discharge should be measured when wading and using the velocity-area method. It is intended as a learning and reference tool for anyone responsible for making wading discharge measurements.

  17. Smartphone for measuring river discharge

    NASA Astrophysics Data System (ADS)

    Peña-Haro, Salvador; Lüthi, Beat; Philippe, Thomas

    2015-04-01

    Smartphones have become powerful and have extended their capacities including different types of sensors. These capabilities make them very interesting for its applications in water management. We have developed a new mobile device application for open-channel flow measurements. This app can be used to determine the flow in e.g. rivers, artificial channels, irrigation ditches, furrows, etc. The smartphone app computes the runoff by analysing a few seconds of a movie that is recorded using the smartphone camera. The runoff is calculated from the estimated water level, surface velocity and from prior knowledge on the channel geometry. The water level is determined by the separation line of image segments with and without optical flow. Via calibration of the smartphone camera position this separation line is mapped to a water level. The surface velocity is calculated using a modified method of the standard Particle Image Velocimetry method. Among the key characteristics of the method is the fact that no tracer particles are needed. There are two flavours of the app. In the first one, all the measurements are taken using the available sensors in the mobile device and all the calculations are made making only use of the device. Three results are given back: the water level, the average surface velocity and discharge. This information can be sent via SMS. In the second one, the movie is send to a central computer where more detailed calculations are made, like fine camera calibration, camera stabilization tuning, definition of the region of interest, the sub-windows for the velocity analysis can be changed, different algorithms can be chosen, etc. It also generates more detailed results. Using smartphones, measurements can be made at much lower cost, since there is no need of permanent installations, which also makes it possible to take measurements in any place.

  18. A comparison between the bottom-track data of an ADCP and Laserscanning Data

    NASA Astrophysics Data System (ADS)

    Schwarzwälder, Kordula

    2015-04-01

    Simon Lutz Technische Universität München, Hydraulic and Water Resources Engineering, München, Germany Peter Rutschmann Technische Universität München, Hydraulic and Water Resources Engineering, München, Germany A standard Acoustic Doppler Current Profiler (ADCP) is constructed, as the name suggests, to gain data about the flow velocity and discharge of e.g. a river. The device is in fact similar to a sonar and uses the Doppler effect to detect the velocity of particles in the water column below the transducers. Beside that standard function it also can track the bottom of a river or sea. The pulses are scattered by the bottom and the shift in the detected velocities between bottom and bulk phase can be used to identify the surface. However this data set depends on the quality of the signal and can be influenced inter alia when the river-bed is moving. Under in situ conditions it is almost not possible to evaluate the quality of this bottom track data. On the other hand e.g. a minimum water depth is needed to get proper results with the ADCP which causes problems in a lab flume. Therefore a reservoir was used for the comparison measurement which could be drained and set nearby dry so the scanning with a RIEGL terrestrial laser scanner became feasible. Within the reservoir due to sedimentation of silt and fine sand fractions a nature-like bottom structure has developed including a talweg, steeper and more shallow areas. This is a perfect structure for the comparison of the results of these two measurement devices. With the Laser-scanning data a 3D model is generated. The bottom track cross sections of the ADCP can be implemented in this model and compared.

  19. Accuracy of the river discharge measurement

    NASA Astrophysics Data System (ADS)

    Chung Yang, Han

    2013-04-01

    Discharge values recorded for water conservancy and hydrological analysis is a very important work. Flood control projects, watershed remediation and river environmental planning projects quite need the discharge measurement data. In Taiwan, we have 129 rivers, in accordance with the watershed situation, economic development and other factors, divided into 24 major rivers, 29 minor rivers and 79 ordinary rivers. If each river needs to measure and record these discharge values, it will be enormous work. In addition, the characteristics of Taiwan's rivers contain steep slope, flow rapidly and sediment concentration higher, so it really encounters some difficulties in high flow measurement. When the flood hazards come, to seek a solution for reducing the time, manpower and material resources in river discharge measurement is very important. In this study, the river discharge measurement accuracy is used to determine the tolerance percentage to reduce the number of vertical velocity measurements, thereby reducing the time, manpower and material resources in the river discharge measurement. The velocity data sources used in this study form Yang (1998). Yang (1998) used the Fiber-optic Laser Doppler Velocimetery (FLDV) to obtain different velocity data under different experimental conditions. In this study, we use these data to calculate the mean velocity of each vertical line by three different velocity profile formula (that is, the law of the wall, Chiu's theory, Hu's theory), and then multiplied by each sub-area to obtain the discharge measurement values and compared with the true values (obtained by the direct integration mode) to obtain the accuracy of discharge. The research results show that the discharge measurement values obtained by Chiu's theory are closer to the true value, while the maximum error is the law of the wall. The main reason is that the law of the wall can't describe the maximum velocity occurred in underwater. In addition, the results also show

  20. Using 3DF GPS heading for improving underway ADCP data

    SciTech Connect

    Griffiths, G.

    1994-08-01

    Systematic error in the cross-track velocity measured under way from shipboard acoustic Doppler current profilers (ADCPs) can be attributed to error in measuring the ship`s heading with a gyrocompass. Drift- and direction-dependent errors in marine gyrocompass may amount to 2 deg - 3 deg, yet they can be difficult to observe. A new system for obtaining attitude information using differential carrier phase measurements on signals from Global Positioning System (GPS) navigation satellites can provide a heading accuracy of 0.05 deg. This paper proposes a method of using these GPS heading measurements as a reference, with the gyrocompass as an interpolation device, to reduce the cross-track velocity error from a shipboard ADCP. The practical application of the method is illustrated by a long north-south section dominated by latitude-induced gyrocompass error, and a small-scale survey where heading-dependent errors in the gyrocompass dominated.

  1. Variance of discharge estimates sampled using acoustic Doppler current profilers from moving boats

    USGS Publications Warehouse

    Garcia, Carlos M.; Tarrab, Leticia; Oberg, Kevin; Szupiany, Ricardo; Cantero, Mariano I.

    2012-01-01

    This paper presents a model for quantifying the random errors (i.e., variance) of acoustic Doppler current profiler (ADCP) discharge measurements from moving boats for different sampling times. The model focuses on the random processes in the sampled flow field and has been developed using statistical methods currently available for uncertainty analysis of velocity time series. Analysis of field data collected using ADCP from moving boats from three natural rivers of varying sizes and flow conditions shows that, even though the estimate of the integral time scale of the actual turbulent flow field is larger than the sampling interval, the integral time scale of the sampled flow field is on the order of the sampling interval. Thus, an equation for computing the variance error in discharge measurements associated with different sampling times, assuming uncorrelated flow fields is appropriate. The approach is used to help define optimal sampling strategies by choosing the exposure time required for ADCPs to accurately measure flow discharge.

  2. General Methods for Quantifying Uncertainty in Discharge Measurements

    NASA Astrophysics Data System (ADS)

    Cohn, Tim; Kiang, Julie; Mason, Robert, Jr.

    2015-04-01

    Developing a general operational method for quantifying uncertainty in streamflow measurements has proven to be a difficult task. The Interpolated Variance Estimator (IVE), which can be applied to situations where sampling involves multiple verticals, has been shown to perform reasonably well at characterizing the nonsystematic errors associated with both irregular channel geometry and pulsating velocities. It is not obvious, however, how to generalize the procedure, or in fact find any alternative procedure, that can take advantage of the continuous current profiling associated with more sophisticated ADCP instruments. Developing a uniform and consistent operational method remains a tall and important order.

  3. Advanced high frequency partial discharge measuring system

    NASA Technical Reports Server (NTRS)

    Karady, George G.

    1994-01-01

    This report explains the Advanced Partial Discharge Measuring System in ASU's High Voltage Laboratory and presents some of the results obtained using the setup. While in operation an insulation is subjected to wide ranging temperature and voltage stresses. Hence, it is necessary to study the effect of temperature on the behavior of partial discharges in an insulation. The setup described in this report can be used to test samples at temperatures ranging from -50 C to 200 C. The aim of conducting the tests described herein is to be able to predict the behavior of an insulation under different operating conditions in addition to being able to predict the possibility of failure.

  4. Computation and error analysis of discharge for the Lake Michigan Diversion Project in Illinois: 1997-99 water years

    USGS Publications Warehouse

    Duncker, James J.; Over, Thomas M.; Gonzalez, Juan A.

    2006-01-01

    Acoustic velocity meters (AVM's) and acoustic Doppler current profilers (ADCP's) were used to measure streamflow at four streamflow-gaging stations in the Chicago River system. The streamflow data were used to compute discharge and to determine the uncertainty in the computed annual mean discharge at each station for the Lake Michigan Diversion Project in Illinois. Descriptions of the instrumentation at each station, stage-area and index-velocity ratings, and methods utilized for computing discharge and estimating missing record are given. Daily mean and annual mean discharges were computed for each station for 1997-99 water years (WY's). A water year is defined as the 12-month period from October 1 through September 30. The water year is designated by the calender year in which it ends and which includes 9 of the 12 months. Thus, the year ending September 30, 1999, is called the 1999 water year. A first-order error analysis was applied to acoustic velocity meter (AVM) data, stage-area, and index-velocity ratings at each streamflow-gaging station. The error analysis results indicate that the uncertainty is sensitive to the value of uncertainty associated with acoustic Doppler cur-rent profiler (ADCP) discharge measurement data. At the Chicago River at Columbus Drive at Chicago, Illinois station for the 1997-99 WY's, the uncertainty, expressed as a standard deviation of the average annual discharge, ranged from 13 to 18 cubic feet per second (ft3/s) when ADCP uncertainty was not included, whereas total uncertainty ranged from 55 to 69 ft3/s when ADCP uncertainty was included. At the Chicago Sanitary and Ship Canal at Romeoville, Illinois station for the 1997-99 WY's, the uncertainty ranged from 18 to 20 ft3/s when ADCP uncertainty was not included, whereas it ranged from 64 to 68 ft3/s when it was included. At the Calumet River below O'Brien Lock and Dam at Chicago, Illinois station for the 1997-99 WY's, the uncertainty ranged from 13 to 22 ft3/s when ADCP

  5. Monitoring tidal currents with a towed ADCP system

    NASA Astrophysics Data System (ADS)

    Sentchev, Alexei; Yaremchuk, Max

    2016-01-01

    The tidal circulation in the semi-enclosed Boulogne harbour (eastern English Channel) is measured during the various stages of the tidal cycle with a low-cost towed Acoustic Doppler Current Profiler (ADCP) system for the first time. The system is equipped with an interpolation algorithm which allows reconstructing space-time evolution of the velocity field for surveys whose duration is comparable or larger than the typical time of tidal variation (1-2 h). The method employs space-time velocity covariances derived from a numerical simulation of the surveyed area by a high-resolution relocatable model "Model for Applications on Regional Scale" (MARS). The covariances are utilized by the optimal interpolation algorithm to obtain the most likely evolution of the velocity field under the constraints provided by the ADCP observations and their error statistics. Technically, the MARS model run provides the first guess (background) evolution of the velocity field in the surveyed area which is then corrected by the data in a statistically consistent manner as it explicitly takes into the account both observational and modeling errors. The quality of the velocity reconstruction was validated against independent bottom-mounted ADCP data, the background model evolution, and against the results of spatial interpolation by Kriging technique. All tests demonstrated significant (30 to 60 %) reduction of the model-data misfit for the velocity field obtained as a result of space-time optimal interpolation. Although the method was applied to recover surface circulation, it can be extended for assessment of the full 4D tidal flow dynamics using the data recorded throughout the entire water column.

  6. Vessel-Mounted ADCP Data Calibration and Correction

    NASA Astrophysics Data System (ADS)

    de Andrade, A. F.; Barreira, L. M.; Violante-Carvalho, N.

    2013-05-01

    A set of scripts for vessel-mounted ADCP (Acoustic Doppler Current Profiler) data processing is presented. The need for corrections in the data measured by a ship-mounted ADCP and the complexities found during installation, implementation and identification of tasks performed by currently available systems for data processing consist the main motivating factors for the development of a system that would be more practical in manipulation, open code and more manageable for the user. The proposed processing system consists of a set of scripts developed in Matlab TM programming language. The system is able to read the binary files provided by the data acquisition program VMDAS (Vessel Mounted Data Acquisition System), Teledyne RDInstruments proprietary, and calculate calibration factors to correct the data and visualize them after correction. For use the new system, it is only necessary that the ADCP data collected with VMDAS program is in a processing diretory and Matlab TM software be installed on the user's computer. Developed algorithms were extensively tested with ADCP data obtained during Oceano Sul III (Southern Ocean III - OSIII) cruise, conducted by Brazilian Navy aboard the R/V "Antares", from March 26th to May 10th 2007, in the oceanic region between the states of São Paulo and Rio Grande do Sul. For read the data the function rdradcp.m, developed by Rich Pawlowicz and available on his website (http://www.eos.ubc.ca/~rich/#RDADCP), was used. To calculate the calibration factors, alignment error (α) and sensitivity error (β) in Water Tracking and Bottom Tracking Modes, equations deduced by Joyce (1998), Pollard & Read (1989) and Trump & Marmorino (1996) were implemented in Matlab. To validate the calibration factors obtained in the processing system developed, the parameters were compared with the factors provided by CODAS (Common Ocean Data Access System, available at http://currents.soest.hawaii.edu/docs/doc/index.html), post-processing program. For the

  7. Hydrodynamic and suspended sediment patterns in the estuarine turbidity zone of a mesotidal estuary from cross-sectional ADCP measurements and numerical simulations

    NASA Astrophysics Data System (ADS)

    Zorndt, Anna Christina; Grünler, Steffen; Schiller, Ulrike; Kösters, Frank

    2015-04-01

    Carefully assessing impacts of human interventions on hydrodynamics, salinity and sediment transport in estuaries has become increasingly important due to the high ecological importance of these systems. Quantifying these changes is commonly done by numerical modeling. However, model results highly rely on the applied model formulations and model parameters. Therefore, validation of the results with measurements is necessary. In case of suspended particulate matter, the use of stationary point measurements is limited due to the high spatial variability of sediments in the water column. This study focusses on modeling the estuarine turbidity maximum of the Weser estuary (Germany), which is a mesotidal and well- to partially mixed estuary. The estuarine turbidity maximum evolves due to known physical effects such as the gravitational circulation, tidal velocity and tidal mixing asymmetries as well as vertical and lateral advection. Those effects also contribute to high lateral and vertical variations which may in nature superposed with secondary currents by local bathymetric features. To increase the understanding of the high spatial and temporal variability of the suspended particulate matter and to validate numerical simulations, 13-hour measurements of three cross-profiles within the estuarine turbidity maximum were carried out in three consecutive years (2009 - 2011). Those consisted of continuous measurements of two vessel-mounted acoustic doppler current profiler, one of which was tilted by 20°. Also, a movable unit (with conductivity, temperature and depth probes, a laser in-situ scattering transmitter and an optical backscatter sensor) was used, also taking a water sample for calibration every 30 minutes. The employed hydrodynamical modeling tool based on the 3D shallow water equations is UnTRIM, described by Casulli and Zanolli (2002), together with the SediMorph module for calculation of transport of suspended and bed load. The model domain has a size of

  8. From mobile ADCP to high-resolution SSC: a cross-section calibration tool

    USGS Publications Warehouse

    Boldt, Justin A.

    2015-01-01

    Sediment is a major cause of stream impairment, and improved sediment monitoring is a crucial need. Point samples of suspended-sediment concentration (SSC) are often not enough to provide an understanding to answer critical questions in a changing environment. As technology has improved, there now exists the opportunity to obtain discrete measurements of SSC and flux while providing a spatial scale unmatched by any other device. Acoustic instruments are ubiquitous in the U.S. Geological Survey (USGS) for making streamflow measurements but when calibrated with physical sediment samples, they may be used for sediment measurements as well. The acoustic backscatter measured by an acoustic Doppler current profiler (ADCP) has long been known to correlate well with suspended sediment, but until recently, it has mainly been qualitative in nature. This new method using acoustic surrogates has great potential to leverage the routine data collection to provide calibrated, quantitative measures of SSC which hold promise to be more accurate, complete, and cost efficient than other methods. This extended abstract presents a method for the measurement of high spatial and temporal resolution SSC using a down-looking, mobile ADCP from discrete cross-sections. The high-resolution scales of sediment data are a primary advantage and a vast improvement over other discrete methods for measuring SSC. Although acoustic surrogate technology using continuous, fixed-deployment ADCPs (side-looking) is proven, the same methods cannot be used with down-looking ADCPs due to the fact that the SSC and particle-size distribution variation in the vertical profile violates theory and complicates assumptions. A software tool was developed to assist in using acoustic backscatter from a down-looking, mobile ADCP as a surrogate for SSC. This tool has a simple graphical user interface that loads the data, assists in the calibration procedure, and provides data visualization and output options. This tool

  9. Use of ADCPs for suspended sediment transport monitoring: An empirical approach

    NASA Astrophysics Data System (ADS)

    Venditti, J. G.; Church, M.; Attard, M. E.; Haught, D.

    2016-04-01

    A horizontally mounted 300 kHz acoustic Doppler current profiler was deployed in Fraser River at Mission, British Columbia, to test its capability to detect size-classified concentration of suspended sediment. Bottle samples in-beam provide a direct calibration of the hADCP signals. We also deployed a 600 kHz vertically mounted ADCP from a boat in combination with bottle samples. Fraser River at Mission is 525 m wide with moderate suspended sediment concentration (up to 350 mg L-1 in our measurements, mostly silt), and a modest sand load only at high flows. We use an entirely empirical approach to calculate the sediment load using ADCPs to test the reliability of acoustic methods when assumptions embedded in the sonar equation about the relation between suspended sediment size and concentration, and acoustic signals are violated. vADCP calibration using matched individual bottle samples and acoustic backscatter departed from the expected theoretical relation. Calibration using depth-averaged sediment concentration and acoustic backscatter more closely matched theoretical expectations, but varied through the season. hADCP calibrations conformed with theoretical expectations and did not exhibit seasonal variation. Silt and sand were successfully discriminated; however, silt dominates the correlations. We found no coherent relation between acoustic attenuation and silt concentration. In-beam results are extended by correlation to estimate mean sediment concentration and total suspended flux in the entire channel: this auxiliary correlation cancels any calibration bias and permits monitoring of size-classified suspended sediment in absence of detailed information of sediment grain-size distribution.

  10. Cathode fall measurement in a dielectric barrier discharge in helium

    SciTech Connect

    Hao, Yanpeng; Zheng, Bin; Liu, Yaoge

    2013-11-15

    A method based on the “zero-length voltage” extrapolation is proposed to measure cathode fall in a dielectric barrier discharge. Starting, stable, and discharge-maintaining voltages were measured to obtain the extrapolation zero-length voltage. Under our experimental conditions, the “zero-length voltage” gave a cathode fall of about 185 V. Based on the known thickness of the cathode fall region, the spatial distribution of the electric field strength in dielectric barrier discharge in atmospheric helium is determined. The strong cathode fall with a maximum field value of approximately 9.25 kV/cm was typical for the glow mode of the discharge.

  11. The rising bubble technique for discharge measurements

    NASA Astrophysics Data System (ADS)

    Luxemburg, W.; Hilgersom, K.; van Eekelen, M.

    2010-12-01

    The rising bubble technique is an elegant method to determine the full discharge of a river or a canal in a short moment of time. The method is not new [Sargent, 1982], but hardly applied so far. The method applies air bubbles released from the bottom of a river or canal. While the bubbles rise to the surface they are dragged along by the current. The deeper the stream and the faster the current the longer will be the distance they are dragged along. The horizontal displacement L, of the bubbles can be observed at the surface of the stream. To obtain a discharge, the rising velocity vr, of the bubble is required additionally. When the rising velocity is assumed constant the discharge per unit width amounts to q= Lvr. Placing a tube on the bottom of the stream and releasing bubbles at regular intervals results in a complete discharge profile. The ongoing research is focusing on factors affecting the rising velocity, solving practicalities in applying the method in the field and how modern image processing techniques can enhance determining in a glance the distance travelled by the bubbles. Surfacing of air bubbles in a canal

  12. Analysis of ADCP data in a heterogeneous current field

    NASA Astrophysics Data System (ADS)

    Fuda, J.-L.; Millot, C.; Hoog, S.; Gerber, H.

    2003-04-01

    criteria to account for the homogeneity/heterogeneity of a given current field in the vicinity of any kind of structure. Additionally, the bottom nepheloïd layer, demonstrated to be present during the whole experiment by transmissometer measurements, was expected to be uplifted and inclined above the observatory. In such conditions, Echo Intensities (EI) of beams standing in the observatory's wake were expected to be higher than those outside the wake. This was checked by studying the link between the current direction and a quantity (DEi) that is the difference between the EI on a given beam and the average of the three other EI's on the other beams at a given depth. Results are very convincing and show that the DEi effectively reach their highest values when currents are oriented toward the related beam. In addition, the DEi's analysis shows that the wake can reach the surface. Numerical simulations of the current field around the observatory were also performed using the CFD (Computational Fluid Dynamics) software FLUENT (2000). The effect of turbulence was considered by means of a k-epsilon model and the near-wall layer was approximated by a standard logarithmic function approach. The observatory was modelled as a block of 2.5x2.5x1 m super (3) and the overall volume around it (45x20x40 m super (3)) was discretized in about 380000 elementary volumes. For these simulations, two values of the mean current (10 cm/s and 30 cm/s) and two configurations for the observatory's orientation (current parallel to sides or to a diagonal) were considered. Although the current lines do not appear to be strongly modified by the observatory, vertical velocities are induced over the whole water depth. Maximum values that could be compared to those from the ADCP, ie at 5m asf, reach about 10 mm/s and values of about 1 mm/s are still encountered at about 15 m asf. Although the modelled vertical velocities appear weaker than the data, they convincingly confirm the disturbance

  13. Estimating discharge measurement uncertainty using the interpolated variance estimator

    USGS Publications Warehouse

    Cohn, T.; Kiang, J.; Mason, R., Jr.

    2012-01-01

    Methods for quantifying the uncertainty in discharge measurements typically identify various sources of uncertainty and then estimate the uncertainty from each of these sources by applying the results of empirical or laboratory studies. If actual measurement conditions are not consistent with those encountered in the empirical or laboratory studies, these methods may give poor estimates of discharge uncertainty. This paper presents an alternative method for estimating discharge measurement uncertainty that uses statistical techniques and at-site observations. This Interpolated Variance Estimator (IVE) estimates uncertainty based on the data collected during the streamflow measurement and therefore reflects the conditions encountered at the site. The IVE has the additional advantage of capturing all sources of random uncertainty in the velocity and depth measurements. It can be applied to velocity-area discharge measurements that use a velocity meter to measure point velocities at multiple vertical sections in a channel cross section.

  14. Discharge rate measurements in a canal using radiotracer methods.

    PubMed

    Pant, H J; Goswami, Sunil; Biswal, Jayashree; Samantray, J S; Sharma, V K

    2016-06-01

    Discharge rates of water were measured in a canal using radiotracer methods with an objective to validate the efficacy of Concrete Volute Pumps (CVPs) installed at various pumping stations along the canal. Pulse velocity and dilution methods were applied to measure the discharge rates using Iodine-131 as a radiotracer. The discharge rate measured in one of the sections of the canal using the pulse velocity method was found to be 22.5m(3)/s, whereas the discharge rates measured using the dilution method in four different sections of the canal varied from 20.27 to 20.62m(3)/s with single CVP in operation. The standard error in discharge rate measurements using dilution method ranged from ±1.1 to ±1.8%. The experimentally measured values of the discharge rate were in good agreement with the design value of the discharge rate (20m(3)/s) thus validating the performance of the CVPs used in the canal. PMID:27016711

  15. Measurements of leakage from Lake Michigan through three control structures near Chicago, Illinois, April-October 1993

    USGS Publications Warehouse

    Oberg, K.A.; Schmidt, A.R.

    1994-01-01

    A total of 213 measurements of leakage were made at three control structures near Chicago, Ill.--the Chicago River Controlling Works (CRCW), Thomas J. O'Brien Lock and Dam (O'Brien), and Wilmette Pumping Station (Wilmette)--using acoustic Doppler current profilers (ADCP's) and dye-dilution techniques. The CRCW consists of the Chicago Lock and two sets of sluice gates connected by a network of harbor walls. Leakage measurements were made in April, May, July, September, and October 1993 using an ADCP. The mean and standard deviation of leakage measured by the ADCP for the Chicago Lock river gate were 133 and 39 cubic feet per second, respectively. The mean and standard deviation of the leakage measurements at CRCW were 204 and 70 cubic feet per second, respectively. The mean and standard deviation of leakage measurements at O'Brien on September 17, 1993, were 21 and 10 cubic feet per second, respectively. The mean and standard deviation leakage measured at Wilmette using the ADCP were 59 and 8 cubic feet per second, respectively, in April 1993. After the pump bays at Wilmette were sealed in July 1993, the leakage dropped to less than 15 cubic feet per second in September 1993. Discharge estimated by dye-dilution at the Chicago Lock on July 15, 1993, was 160 cubic feet per second, or within 8 percent of the discharge measured with the ADCP. (USGS)

  16. Power Measurements of Spark Discharge Experiments

    NASA Astrophysics Data System (ADS)

    Navarro-González, Rafael; Romero, Alfredo; Honda, Yasuhiro

    1998-04-01

    An accurate and precise knowledge of the amount of energy introduced into prebiotic discharge experiments is important to understand the relative roles of different energy sources in the synthesis of organic compounds in the primitive Earth's atmosphere and other planetary atmospheres. Two methods widely used to determine the power of spark discharges were evaluated, namely calorimetric and oscilloscopic, using a chemically inert gas. The power dissipated by the spark in argon at 500 Torr was determined to be 2.4 (^+12%/_-17%) J s^-1 by calorimetry and 5.3 +/- 15%) J s^-1 by the oscilloscope. The difference between the two methods was attributed to (1) an incomplete conversion of the electric energy into heat, and (2) heat loss from the spark channel to the connecting cables through the electrodes. The latter contribution leads to an unwanted effect in the spark channel by lowering the spark product yields as the spark channel cools by mixing with surrounding air and by losing heat to the electrodes. Once the concentrations of the spark products have frozen at the freeze-out temperature, any additional loss of heat from the spark channel to the electrodes has no consequence in product yields. Therefore, neither methods accurately determines the net energy transferred to the system. With a lack of a quantitative knowledge of the amount of heat loss from the spark channel during the interval from ignition of the spark to when the freeze-out temperature is reached, it is recommended to derive the energy yields of the spark products from the mean value of the two methods with the uncertainty being their standard deviation. For the case of argon at 500 Torr, this would be 3.8 (+/-50%) J s^-1.

  17. Measurement of peak discharge at width contractions by indirect methods

    USGS Publications Warehouse

    Matthai, Howard Frederick

    1967-01-01

    This chapter describes procedures for measuring peak discharges using open-channel width contractions. Field and office procedures limited to this method are described. The discharge equation based on the continuity and energy equations between an approach cross section and the contracted section under a bridge or contraction is given. Contractions are classified into four geometric types. Discharge coefficients and computation procedures are given with a complete facsimile example of computation of a contracted-opening measurement. Additional procedures are given for multiple-opening contractions.

  18. Vertical Structure and Dynamics of the Beaufort Gyre Subsurface Layer from ADCP Obervations

    NASA Astrophysics Data System (ADS)

    Torres, D. J.; Krishfield, R. A.; Proshutinsky, A. Y.; Timmermans, M. L. E.

    2014-12-01

    As part of the Beaufort Gyre Observing System (BGOS), several Acoustic Doppler Current Profilers (ADCPs) have been maintained at moorings in different locations in the Canada Basin since 2005 to measure upper ocean velocities and sea ice motion. The ADCP data have been analyzed to better understand relationships among different components of forcing driving the sea ice and upper ocean layer including: winds, tides, and horizontal and vertical density gradients in the ocean. Specific attention is paid to data processing and analysis to separate inertial and tidal motions in these regions in the vicinity of the critical latitudes. In addition, we describe the dynamic characteristics of halocline eddies and estimate their kinetic energy and their role in the total energy balance in this region. Ice-Tethered Profiler (ITP) data are used in conjunction with the ADCP measurements to identify relationships between T-S and vertical velocity structures in the mixed layer and deeper. Seasonal and interannual variability in all parameters are also discussed and causes of observed changes are suggested.

  19. Bonneville Second Powerhouse Tailrace and High Flow Outfall: ADCP and drogue release field study

    SciTech Connect

    Cook, Christopher B.; Richmond, Marshall C.; Guensch, Gregory R.

    2001-03-20

    The Bonneville Project is one of four US Army Corps of Engineers operated dams along the Lower Columbia River. Each year thousands of smelt pass through this Project on their way to the Pacific Ocean. High flow outfalls, if specifically designed for fish passage, are thought to have as good or better smelt survival rates as spillways. To better understand the hydrodynamic flow field around an operating outfall, the Corps of Engineers commissioned measurement of water velocities in the tailrace of the Second Powerhouse. These data also are necessary for proper calibration and verification of three-dimensional numerical models currently under development at PNNL. Hydrodynamic characterization of the tailrace with and without the outfall operating was accomplished through use of a surface drogue and acoustic Doppler current profiler (ADCP). Both the ADCP and drogue were linked to a GPS (global positioning system); locating the data in both space and time. Measurements focused on the area nearest to the high flow outfall, however several ADCP transects and drogue releases were performed away from the outfall to document ambient flow field conditions when the outfall was not operating.

  20. The Acoustic Doppler Current Profiler (adcp) as a Tool for Ocean Exploration

    NASA Astrophysics Data System (ADS)

    Rossby, H. T.; Flagg, C. N.; Ortner, P. B.

    2010-12-01

    Although the ADCP has been around for three decades it remains somewhat underappreciated for its excellent exploratory potential in several areas. First and perhaps foremost because oceanographers have always been handicapped in their ability to resolve horizontal patterns below the surface, the ADCP opens up a powerful and very cost-effective window into the ocean water column to explore the meso- and submesoscale velocity field at very high resolution. This is particularly true when ADCP data are collected from just a single instrument mounted on a vessel operating repeatedly over an extended period of time in an area or along a route. The ADCP greatly expands upon hydrographic and XBT information by directly measuring the velocity field accurately without any assumptions about geostrophy or the velocity of reference layers. Second, vessels in transit can characterize currents and eddy activities across contrasting oceanic regimes and highlight their relation to the steering role of bottom topography. Third, even though the ADCP is a single frequency device the backscatter signal recorded by the ADCP is showing considerable skill in revealing space-time patterns of biomass variability. Here, through data we have taken over the past ten years, we survey the ADCP’s future as a tool of exploration across several dimensions: space, time, and parameter (physics and biology). Today, thanks to the ADCP we have a far more accurate picture of the velocity and vorticity structure of fronts and eddies. At the surface a front is simply a transition between different water masses, but the actual transition will often consist a water-mass and potential vorticity jump on a significantly smaller scale within the frontal feature. The same applies to the boundaries of rings and lenses. Commercial vessels equipped with ADCPs operating on a repeat schedule can document underlying patterns that single transects or cruises cannot detect due to inherent eddy activity. Newly

  1. New 3-D flow interpolation method on moving ADCP data

    NASA Astrophysics Data System (ADS)

    Tsubaki, R.; Kawahara, Y.; Muto, Y.; Fujita, I.

    2012-05-01

    A simple but accurate interpolation procedure for obtaining the three-dimensional distribution of three-component velocity data, from moving acoustic doppler current profiler (ADCP) observation data, is proposed. For understanding actual flow structure within a river with complex bathymetry, the three-dimensional mean velocity field provides a basic picture of the flow. For obtaining the three-dimensional distribution of three-component velocity data, in this work, anisotropic gridding was introduced in order to remove the random component of measured velocity data caused by the turbulence of the flow and measurement error. A continuity correction based on the pressure equation was used to reduce both random and systematic errors. The accuracy of the developed method was evaluated using three-dimensional flow simulation data from a detached-eddy simulation (DES). By using the procedure developed, the complex flow structure surrounding the spur dikes section in the Uji River was successfully visualized and explored. The proposed method shows superiorities in both accuracy and consistency for the interpolated velocity field, as compared to the kriging and inverse-distance weighted (IDW) methods.

  2. [Study of plasma temperature measurements for oxygen discharge].

    PubMed

    Li, Liu-Cheng; Wang, Zeng-Qiang; Li, Gu-Fu; Duo, Li-Ping

    2011-10-01

    A radio-frequency discharge setup was constructed by two shell-shaped copper electrodes and a 30 cm long pyrex glass tube (i. d. = 1.65 cm) to examine the gas temperature of oxygen plasma in electric discharge oxygen iodine laser. The discharge was supplied by a 500 watt, 13.56 MHz radio-frequency power. The gas pressure in the discharge cavity was 1 330 Pa. The temperature of oxygen discharge plasma was measured by using the P branch of O2 (b, v = 0) rotational emission spectrum. Two methods were used to deduce the oxygen gas temperature. They are Boltzman plotting method and computer simulating spectrum method, respectively. Gauss fitting method was used to distinguish spectrum peaks for lower resolution spectrum. The spectrum peak area was used to characterize the optical emission intensity. The gas temperature of oxygen discharge plasma was obtained by Boltzmann plotting method. Alternatively, the optical emission spectrum was simulated by computer modeling with spectrometer slit function which was obtained by He-Ne laser. Consequently, the gas temperature of oxygen plasma was obtained by comparing the computer simulating spectrum and the experimentally observed spectrum according to the least square fitting rule. The measurement results with the two methods agree well. It was concluded that the simple optical technique can be used conveniently in the temperature diagnostics of oxygen radio-frequency discharge plasma. PMID:22250527

  3. River discharge measurements by using helicopter-mounted radar

    USGS Publications Warehouse

    Melcher, N.B.; Costa, J.E.; Haeni, F.P.; Cheng, R.T.; Thurman, E.M.; Buursink, M.; Spicer, K.R.; Hayes, E.; Plant, W.J.; Keller, W.C.; Hayes, K.

    2002-01-01

    The United States Geological Survey and the University of Washington collaborated on a series of initial experiments on the Lewis, Toutle, and Cowlitz Rivers during September 2000 and a detailed experiment on the Cowlitz River during May 2001 to determine the feasibility of using helicopter-mounted radar to measure river discharge. Surface velocities were measured using a pulsed Doppler radar, and river depth was measured using ground-penetrating radar. Surface velocities were converted to mean velocities, and horizontal registration of both velocity and depth measurements enabled the calculation of river discharge. The magnitude of the uncertainty in velocity and depth indicate that the method error is in the range of 5 percent. The results of this experiment indicate that helicopter-mounted radar can make the rapid, accurate discharge measurements that are needed in remote locations and during regional floods.

  4. Future Concepts for River Discharge Measurements with Microwave Radar

    NASA Astrophysics Data System (ADS)

    Farquharson, G.; Plant, W. J.; Chickadel, C.; Jessup, A. T.

    2010-12-01

    River discharge has traditionally been estimated by combining in situ measurements of stage with in situ measurements of velocity and channel cross-section to derive stage-discharge rating curves. These measurements are time consuming and resource intensive, and only represent the state of the river at a single location. Thus, various researchers have studied non-contact stream gauging techniques using remote sensing instrumentation to estimate discharge. For example, airborne or space-borne radar has been used to measure surface velocity, and altimetry has been used to measure surface elevation. Other approaches have included coupling remote sensing measurements of water surface elevation and river channel width with a hydrodynamic model to estimate discharge. However, in all of these studies, prior knowledge of either the topology of the river bed or the channel roughness was assumed. This paper examines the potential of microwave radar to measure river discharge. Ultimately, our goal is to relate surface features to subsurface topology, thereby allowing non water-penetrating remote sensing measurements to estimate discharge. Our approach is to use interferometric Doppler radar to measure water elevation and surface velocity over a stretch of the river. If the channel topology is known, then discharge estimates can be computed from these measurements. To monitor changes in the channel, we draw on results from laboratory measurements and numerical simulations that demonstrate that variations in the mean water elevation along the river are related to the subsurface topography of the river bed. If the channel topology is not known, we propose to use a simple hydrodynamic model to estimate the depth. To do this, we compute the slope of the river using the water elevation measurements, and then estimate the pressure gradient in the river from the slope. In the case of steady, unstratified, open channel flow, the pressure gradient is balanced by the bottom stress

  5. Ion energy measurements in steady state discharges @f|

    NASA Astrophysics Data System (ADS)

    Schwager * *, L. A.; Hsu, W. L.; Tung, D. M.

    1990-02-01

    The energy distribution of ions incident on the grounded surface (cathode) of a direct current (DC) glow discharge is measured. This incident energy determines the effectiveness of glow discharge cleaning in removing gases and impurities from the vessel surface. We have found that the incident ion energy falls significantly below the anode potential when the mean free path for charge exchange is less than the width of the cathode sheath which is approximately the Child-Langmuir sheath width. The DC discharge provides a current density at the grounded surface of typically 17 micro-Amps/cm2. A gas mix of deuterium and argon at pressures up to 40 mTorr is ignited to form the plasma. A mass and energy analyzer measures the energy distribution of the ion stream which passes through an aperture in the center of the electrically grounded surface.

  6. Culvert analysis program for indirect measurement of discharge

    USGS Publications Warehouse

    Fulford, Janice M.

    1993-01-01

    A program based on the U.S. Geological Survey (USGS) methods for indirectly computing peak discharges through culverts allows users to employ input data formats used by the water surface profile program (WSPRO). The program can be used to compute discharge rating surfaces or curves that describe the behavior of flow through a particular culvert or to compute discharges from measurements of upstream of the gradually varied flow equations and has been adapted slightly to provide solutions that minimize the need for the user to determine between different flow regimes. The program source is written in Fortran 77 and has been run on mini-computers and personal computers. The program does not use or require graphics capability, a color monitor, or a mouse.

  7. Contaminant discharge and uncertainty estimates from passive flux meter measurements

    NASA Astrophysics Data System (ADS)

    Klammler, Harald; Hatfield, Kirk; GuimarãEs da Luz, Joana AngéLica; Annable, Michael D.; Newman, Mark; Cho, Jaehyun; Peacock, Aaron; Stucker, Valerie; Ranville, James; Cabaniss, Steven A.; Rao, P. S. C.

    2012-02-01

    The passive flux meter (PFM) measures local cumulative water and contaminant fluxes at an observation well. Conditional stochastic simulation accounting for both spatial correlation and data skewness is introduced to interpret passive flux meter observations in terms of probability distributions of discharges across control planes (transects) of wells. An estimator of the effective number of independent data is defined and applied in the development of two significantly simpler approximate methods for estimating discharge distributions. One method uses a transformation of the t statistic to account for data skewness and the other method is closely related to the classic bootstrap. The approaches are demonstrated with passive flux meter data from two field sites (a trichloroethylene [TCE] plume at Ft. Lewis, WA, and a uranium plume at Rifle, CO). All methods require that the flux heterogeneity is sufficiently represented by the data and maximum differences in discharge quantile estimates between methods are ˜7%.

  8. Rotational CARS Temperature Measurements in Nanosecond Pulse Discharge Plasmas

    NASA Astrophysics Data System (ADS)

    Zuzeek, Yvette; Takashima, Keisuke; Adamovich, Igor; Lempert, Walter

    2009-10-01

    Time-resolved and spatially resolved temperatures in repetitively pulsed nanosecond discharges in air and ethylene-air mixtures have been measured by purely rotational Coherent Anti-Stokes Raman Specroscopy (CARS). The experiments have been done in a capacitively coupled plane-to-plane discharge and in an atmospheric pressure near-surface Dielectric Barrier Discharge (DBD), both powered by repetitive nanosecond duration voltage pulses. Gated ICCD camera images demonstrated that the capacitively coupled discharge plasma remains diffuse and stable, with no sign of arc filaments. Comparison of the experimental results with plasma chemical kinetic modeling calculations shows good agreement. The results demonstrate that the rate of heating in the fuel-air plasma is significantly more rapid compared to the one in the air plasma. Kinetic model analysis shows that this occurs due to exothermic reactions of fuel with radical species generated in the plasma, such as O atoms. The present results provide additional insight into kinetics of hydrocarbon fuel oxidation in low-temperature plasmas and into the mechanism of localized heating of air flows by nanosecond DBD discharges.

  9. Measurement of the electron density in Transient Spark discharge

    NASA Astrophysics Data System (ADS)

    Janda, Mário; Martišovitš, Viktor; Hensel, Karol; Dvonč, Lukáš; Machala, Zdenko

    2014-12-01

    This paper presents our measurements of the electron density in a streamer-to-spark transition discharge, which is named transient spark (TS), in atmospheric pressure air. Despite the dc applied voltage, TS has a pulsed character with short (˜10-100 ns) high current (>1 A) pulses, with a repetition frequency on the order of kHz. The electron density ne ˜ 1017 cm-3 at maximum is reached in TS with repetition frequencies below ˜3 kHz, using relatively low power delivered to the plasma (0.2-3 W). The temporal evolution of ne was estimated from the resistance of the plasma discharge, which was obtained by a detailed analysis of the electric circuit representing the TS and the discharge diameter measurements using a fast intensified charge-coupled device (iCCD) camera. This estimate was compared with ne calculated from the measured Stark broadening of several atomic lines: Hα, N at 746 nm, and O triplet at 777 nm. Good agreement was obtained, although the method based on the plasma resistance is sensitive to an accurate determination of the discharge diameter. We have found that this method is also limited for strongly ionized plasmas. On the other hand, a lower ne detection limit can be obtained by this method than from the Stark broadening of atomic lines.

  10. Measurement of discharge by the moving-boat method

    USGS Publications Warehouse

    Smoot, George F.; Novak, Charles E.

    1969-01-01

    This chapter describes the procedures for measuring discharge in large streams by the moving-boat technique. During the traverse of a boat across a stream, a sonic sounder records the geometry of the cross section, and a continuously operating current meter senses the combined stream and boat velocities. These data are converted to discharge for the cross section quickly, efficiently, and inexpensively. Measurements obtained by the moving-boat technique compare within 5 percent of measurements obtained by conventional means. Field and office procedures applicable to this method are outlined. Theory of technique is developed and equipment required is described. Selection and preparation of the cross section is detailed. A complete facsimile example of computation of a moving-boat measurement is given, and the determination and application of adjustment factors are described.

  11. [Air Dielectric Barrier Discharge Emission Spectrum Measurement and Particle Analysis of Discharge Process].

    PubMed

    Shen, Shuang-yan; Jin, Xing; Zhang, Peng

    2016-02-01

    The emission spectrum detection and diagnosis is one of the most common methods of application to the plasma. It provides wealth of information of the chemical and physical process of the plasma. The analysis of discharge plasma dynamic behavior plays an important role in the study of gas discharge mechanism and application. An air dielectric discharge spectrum measuring device was designed and the emission spectrum data was measured under the experimental condition. The plasma particles evolution was analyzed from the emission spectrum. The numerical calculation model was established and the density equation, energy transfer equation and the Boltzmann equation was coupled to analyze the change of the particle density to explain the emission spectrum characteristics. The results are that the particle density is growing with the increasing of reduced electric field. The particle density is one or two orders of magnitude difference for the same particle at the same moment for the reduced electric field of 40, 60 or 80 Td. A lot of N₂ (A³), N₂ (A³) and N₂ (C³) particles are generated by the electric field excitation. However, it transforms quickly due to the higher energy level. The transformation returns to the balance after the discharge of 10⁻⁶ s. The emission spectrometer measured in the experiments is mostly generated by the transition of excited nitrogen. The peak concentration of O₂ (A¹), O₂ (B¹) and O₂ (A³ ∑⁺u) is not low compared to the excited nitrogen molecules. These particles energy is relatively low and the transition spectral is longer. The spectrometer does not capture the oxygen emission spectrum. And the peak concentration of O particles is small, so the transition emission spectrum is weak. The calculation results of the stabled model can well explain the emission spectrum data. PMID:27209731

  12. Surface charge measurements in barrier discharges on different time scales

    NASA Astrophysics Data System (ADS)

    Wild, Robert; Volkhausen, Christian; Benduhn, Johannes; Stollenwerk, Lars

    2015-09-01

    The deposition of surface charge in barrier discharges is a process that influences the ongoing discharge significantly. This contribution presents the measurement of absolute surface charge densities and their dynamics in a laterally extended setup. An electro-optic BSO crystal is used as dielectric. The absolute charge density on its surface is deduced from the change of polarisation of light passing the crystal. Using different temporal resolutions, the behavior of charge is investigated on three different time scales. The highest temporal resolution of the technique is in the order of hundreds of nanoseconds. Therefore it is possible for the first time to observe the charge deposition process during an active discharge. On the time scale of the applied voltage period (several microseconds), the conservation mechanisms of a lateral discharge pattern is investigated. For this, the influence of surface charge and metastable species in the volume is estimated. Further, the behavior of the surface charge spots on a variation of the external voltage and gas pressure is studied. Measurements on a time scale in the magnitude of seconds reveal charge decay and transport phenomena. This work was funded by the Deutsche Forschungsgemeinschaft.

  13. 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

  14. Standards for discharge measurement with standardized nozzles and orifices

    NASA Technical Reports Server (NTRS)

    1940-01-01

    The following standards give the standardized forms for two throttling devices, standard nozzles and standard orifices, and enable them to be used in circular pipes without calibration. The definition of the standards are applicable in principle to the calibration and use of nonstandardized throttling devices, such as the venturi tube. The standards are valid, likewise, as a basis for discharge measurements in the German acceptance standards.

  15. Evaluation of ADCP apparent bed load velocity in a large sand-bed river: Moving versus stationary boat conditions

    USGS Publications Warehouse

    Jamieson, E.C.; Rennie, C.D.; Jacobson, R.B.; Townsend, R.D.

    2011-01-01

    Detailed mapping of bathymetry and apparent bed load velocity using a boat-mounted acoustic Doppler current profiler (ADCP) was carried out along a 388-m section of the lower Missouri River near Columbia, Missouri. Sampling transects (moving boat) were completed at 5- and 20-m spacing along the study section. Stationary (fixed-boat) measurements were made by maintaining constant boat position over a target point where the position of the boat did not deviate more than 3 m in any direction. For each transect and stationary measurement, apparent bed load velocity (vb) was estimated using ADCP bottom tracking data and high precision real-time kinematic (RTK) global positioning system (GPS). The principal objectives of this research are to (1) determine whether boat motion introduces a bias in apparent bed load velocity measurements; and (2) evaluate the reliability of ADCP bed velocity measurements for a range of sediment transport environments. Results indicate that both high transport (vb>0.6 m/s) and moving-boat conditions (for both high and low transport environments) increase the relative variability in estimates of mean bed velocity. Despite this, the spatially dense single-transect measurements were capable of producing detailed bed velocity maps that correspond closely with the expected pattern of sediment transport over large dunes. ?? 2011 American Society of Civil Engineers.

  16. Practical Experience of Discharge Measurement in Flood Conditions with ADP

    NASA Astrophysics Data System (ADS)

    Vidmar, A.; Brilly, M.; Rusjan, S.

    2009-04-01

    Accurate discharge estimation is important for an efficient river basin management and especially for flood forecasting. The traditional way of estimating the discharge in hydrological practice is to measure the water stage and to convert the recorded water stage values into discharge by using the single-valued rating curve .Relationship between the stage and discharge values of the rating curve for the extreme events are usually extrapolated by using different mathematical methods and are not directly measured. Our practice shows that by using the Accoustic Doppler Profiler (ADP) instrument we can record the actual relation between the water stage and the flow velocity at the occurrence of flood waves very successfully. Measurement in flood conditions it is not easy task, because of high water surface velocity and large amounts of sediments in the water and floating objects on the surface like branches, bushes, trees, piles and others which can also easily damage ADP instrument. We made several measurements in such extreme events on the Sava River down to the nuclear power plant Kr\\vsko where we have install fixed cable way. During the several measurement with traditional "moving-boat" measurement technique a mowing bed phenomenon was clearly seen. Measuring flow accurately using ADP that uses the "moving-boat" technique, the system needs a reference against which to relate water velocities to. This reference is river bed and must not move. During flood events we detected difficulty finding a static bed surface to which to relate water velocities. This is caused by motion of the surface layer of bed material or also sediments suspended in the water near bed very densely. So these traditional »moving-boat« measurement techniques that we normally use completely fail. Using stationary measurement method to making individual velocity profile measurements, using an Acoustic Doppler Profiler (ADP), at certain time at fixed locations across the width of a stream gave

  17. Comparative Spectroscopic Temperature Measurements In Hydrogen Hollow Cathode Glow Discharge

    NASA Astrophysics Data System (ADS)

    Majstorovic, G. Lj.; Šišovic, N. M.; Konjevic, N.

    2010-07-01

    We report results of optical emission spectroscopy measurements of rotational Trot and translational temperature Ttr of hydrogen molecules. The light source was hollow cathode glow discharge with titanium cathode operated in hydrogen at low pressure. The rotational temperature of excited electronic states of H2 was determined either from relative line intensities of the R branch of the GK ? B band or from the Q branch of the Fulcher-a diagonal band. The population of excited energy levels, determined from relative line intensities, was used to derive ro-vibronic temperature of the ground state of hydrogen molecule.

  18. Advances in the Rising Bubble Technique for discharge measurement

    NASA Astrophysics Data System (ADS)

    Hilgersom, Koen; Luxemburg, Willem; Willemsen, Geert; Bussmann, Luuk

    2014-05-01

    Already in the 19th century, d'Auria described a discharge measurement technique that applies floats to find the depth-integrated velocity (d'Auria, 1882). The basis of this technique was that the horizontal distance that the float travels on its way to the surface is the image of the integrated velocity profile over depth. Viol and Semenov (1964) improved this method by using air bubbles as floats, but still distances were measured manually until Sargent (1981) introduced a technique that could derive the distances from two photographs simultaneously taken from each side of the river bank. Recently, modern image processing techniques proved to further improve the applicability of the method (Hilgersom and Luxemburg, 2012). In the 2012 article, controlling and determining the rising velocity of an air bubble still appeared a major challenge for the application of this method. Ever since, laboratory experiments with different nozzle and tube sizes lead to advances in our self-made equipment enabling us to produce individual air bubbles with a more constant rising velocity. Also, we introduced an underwater camera to on-site determine the rising velocity, which is dependent on the water temperature and contamination, and therefore is site-specific. Camera measurements of the rising velocity proved successful in a laboratory and field setting, although some improvements to the setup are necessary to capture the air bubbles also at depths where little daylight penetrates. References D'Auria, L.: Velocity of streams; A new method to determine correctly the mean velocity of any perpendicular in rivers and canals, (The) American Engineers, 3, 1882. Hilgersom, K.P. and Luxemburg, W.M.J.: Technical Note: How image processing facilitates the rising bubble technique for discharge measurement, Hydrology and Earth System Sciences, 16(2), 345-356, 2012. Sargent, D.: Development of a viable method of stream flow measurement using the integrating float technique, Proceedings of

  19. Acoustic Doppler Current Profiler Data Processing System manual [ADCP

    USGS Publications Warehouse

    Cote, Jessica M.; Hotchkiss, Frances S.; Martini, Marinna; Denham, Charles R.; revisions by Ramsey, Andree L.; Ruane, Stephen

    2000-01-01

    This open-file report describes the data processing software currently in use by the U.S. Geological Survey (USGS), Woods Hole Coastal and Marine Science Center (WHCMSC), to process time series of acoustic Doppler current data obtained by Teledyne RD Instruments Workhorse model ADCPs. The Sediment Transport Instrumentation Group (STG) at the WHCMSC has a long-standing commitment to providing scientists high quality oceanographic data published in a timely manner. To meet this commitment, STG has created this software to aid personnel in processing and reviewing data as well as evaluating hardware for signs of instrument malfunction. The output data format for the data is network Common Data Form (netCDF), which meets USGS publication standards. Typically, ADCP data are recorded in beam coordinates. This conforms to the USGS philosophy to post-process rather than internally process data. By preserving the original data quality indicators as well as the initial data set, data can be evaluated and reprocessed for different types of analyses. Beam coordinate data are desirable for internal and surface wave experiments, for example. All the code in this software package is intended to run using the MATLAB program available from The Mathworks, Inc. As such, it is platform independent and can be adapted by the USGS and others for specialized experiments with non-standard requirements. The software is continuously being updated and revised as improvements are required. The most recent revision may be downloaded from: http://woodshole.er.usgs.gov/operations/stg/Pubs/ADCPtools/adcp_index.htm The USGS makes this software available at the user?s discretion and responsibility.

  20. 2013 Mt. Etna Pyroclastic Activity through the ADCP Recordings of NEMO-SN1 Multidisciplinary Seafloor Observatory

    NASA Astrophysics Data System (ADS)

    Lo Bue, N.; Sgroi, T.; Giovinetti, G.; Marinaro, G.; Favali, P.

    2014-12-01

    The Acoustic Doppler Current Profiler (ADCP) is one of the most useful sensor used to measure speed and direction of sea currents in the water column. More often ADCPs are being also used to monitor concentration of suspended matter in rivers or in marine environments by the analysis of the acoustic backscatter intensity. In the framework of the European Research Infrastructure EMSO (European Multidisciplinary Seafloor and water-column Observatory, www.emso-eu.org), its cabled node, the NEMO-SN1 multidisciplinary seafloor observatory, was deployed in the Western Ionian Sea (Southern Italy) at a depth of 2100 m, about 25 km off-shore Eastern Sicily close to the submarine slope of the Mt. Etna volcano. Starting from February 2013, the Mt. Etna was interested by thirteen different parossistic events producing intense eruption followed by pyroclastic fallout that reached distances of tens kilometres from the eruptive centre. Four of these events affected the ESE sector with a consequent fallout in the Western Ionian Sea and they were detected by NEMO-SN1. In fact, its scientific payload also included an ADCP (RDI WorkHorse 600 kHz) with the main aim to monitor the hydrodynamic conditions of about 30 metres of the water column above the station. Surprisingly, this sensor offered spectacular recordings of the Mt. Etna pyroclastic activity occurred on 2013 wich affected the ESE sector. This work aims to present new records of pyroclastic fallout associated to explosive events observed at sea bottom by the analysis of backscatter signal of the ADCP. A multidisciplinary approach taking into account the Mt. Etna eruptive activity as well as the local oceanographic dynamic is necessary to describe marine processes involved in volcanic ash sedimentation.

  1. Detecting groundwater discharge dynamics from point-to-catchment scale in a lowland stream: combining hydraulic and tracer methods

    NASA Astrophysics Data System (ADS)

    Poulsen, J. R.; Sebok, E.; Duque, C.; Tetzlaff, D.; Engesgaard, P. K.

    2015-04-01

    Detecting, quantifying and understanding groundwater discharge to streams are crucial for the assessment of water, nutrient and contaminant exchange at the groundwater-surface water interface. In lowland agricultural catchments with significant groundwater discharge this is of particular importance because of the risk of excess leaching of nutrients to streams. Here we aim to combine hydraulic and tracer methods from point-to-catchment scale to assess the temporal and spatial variability of groundwater discharge in a lowland, groundwater gaining stream in Denmark. At the point-scale, groundwater fluxes to the stream were quantified based on vertical streambed temperature profiles (VTPs). At the reach scale (0.15-2 km), the spatial distribution of zones of focused groundwater discharge was investigated by the use of distributed temperature sensing (DTS). Groundwater discharge to the stream was quantified using differential gauging with an acoustic Doppler current profiler (ADCP). At the catchment scale (26-114 km2), runoff sources during main rain events were investigated by hydrograph separations based on electrical conductivity (EC) and stable isotopes 2H/1H. Clear differences in runoff sources between catchments were detected, ranging from approximately 65% event water for the most responsive sub-catchment to less than 10% event water for the least responsive sub-catchment. This was supported by the groundwater head gradients, where the location of weaker gradients correlated with a stronger response to precipitation events. This shows a large variability in groundwater discharge to the stream, despite the similar lowland characteristics of sub-catchments indicating the usefulness of environmental tracers for obtaining information about integrated catchment functioning during precipitation events. There were also clear spatial patterns of focused groundwater discharge detected by the DTS and ADCP measurements at the reach scale indicating high spatial variability

  2. Detecting groundwater discharge dynamics from point to catchment scale in a lowland stream: combining hydraulic and tracer methods

    NASA Astrophysics Data System (ADS)

    Poulsen, J. B.; Sebok, E.; Duque, C.; Tetzlaff, D.; Engesgaard, P. K.

    2014-12-01

    Detecting, quantifying, and understanding groundwater discharge to streams are crucial for the assessment of water, nutrient and contaminant exchange at the surface water-groundwater interface. In lowland agricultural catchments with significant groundwater discharge this is of particular importance because of the risk of excess leaching of nutrients to streams. Here we aim to combine hydraulic and tracer methods from point to catchment scale to assess the temporal and spatial variability of groundwater discharge in a lowland, groundwater gaining stream in Denmark. At the point scale groundwater fluxes to the stream were quantified based on Vertical streambed Temperature Profiles (VTP). At the reach scale (0.15-2 km) the spatial distribution of zones of focused groundwater discharge was investigated by the use of Distributed Temperature Sensing (DTS). Groundwater discharge to the stream was quantified using differential gauging with an Acoustic Doppler Current Profiler (ADCP). At the catchment scale (26-114 km2) runoff sources during main rain events were investigated by hydrograph separations based on Electrical Conductivity (EC) and stable isotopes 2H / 1H. Clear differences in runoff sources between catchments were detected, ranging from approximately 65% event water for the most responsive sub-catchment and less than 10% event water for the least responsive sub-catchment. This shows a large variability in groundwater discharge to the stream, despite the similar lowland characteristics of sub-catchments, indicating the usefulness of environmental tracers for obtaining information about integrated catchment functioning during events. There were also clear spatial patterns of focused groundwater discharge detected by the DTS and ADCP measurements at the reach scale suggesting high spatial variability, where a significant part of groundwater discharge was concentrated in few zones indicating the possibility of concentrated nutrient or pollutant transport-zones from

  3. Temporal and spatial variability of ADCP backscatter on a continental slope

    NASA Astrophysics Data System (ADS)

    Sindlinger, Laurie R.; Biggs, Douglas C.; DiMarco, Steven F.

    2005-01-01

    Previous research has shown that acoustic volume backscatter intensity (ABI) from an acoustic Doppler current profiler (ADCP) can be a proxy for zooplankton and micronekton biomass over time or space. As part of NOAA's Sperm Whale and Acoustic Monitoring Program (SWAMP) and a follow-on ichthyoplankton survey (SEAMAP), a ship-mounted 300-kHz broadband ADCP collected current velocity and ABI data from July to September 2001 in the northeast Gulf of Mexico. The present study sought to compare/contrast the variability in ABI both spatially and temporally using the data obtained from the SWAMP and SEAMAP cruises. The ADCP data were averaged over 2 min and 4 m vertical bins from 16 to 56 m below sea surface. Usually, ABI in this epipelagic realm averaged 3 dB higher at night than during the day because of diel vertical migration of zooplankton and micronekton into these near surface waters, while in a region having cyclonic circulation along the continental margin of the northeast Gulf, ABI averaged 6 dB higher than in an anticyclonic warm filament there. Wet displacement volumes (WDV) were measured using Bongo net tows to estimate that a 6 dB increase in ABI was equivalent to an increase from 9 to 10.5 ml WDV of plankton+micronekton per 100 m 3. Sperm whale abundance has been shown to be positively correlated with regions of locally high ABI, and sperm whale sightings during SWAMP were also compared to our ABI measurements. Spectral and Empirical Orthogonal Function analyses were performed on subsets of the ABI data for which 10-14 day time series were available and showed 2-3 day periodicity near-surface, corresponding to spatial scales of 10 1-10 2 km. During summer 2001, the mesoscale circulation along the subtropical continental margin in the northeastern Gulf was found to be the principal forcing factor for low frequency ABI variation. Increased backscatter observations are also correlated with offshore flow from the continental margin to the deep ocean

  4. Langmuir probe measurements of weakly collisional electropositive RF discharge plasmas

    NASA Astrophysics Data System (ADS)

    Bryant, Paul; Dyson, Anthony; Allen, John E.

    2001-05-01

    We report on Langmuir probe measurements of low-pressure (0.1-20 Pa) electropositive plasmas in an RF discharge at 13.56 MHz. From the probe I-V characteristic it is found that the electron density inferred from the ion current in the ion saturation region using radial motion (Allen, Boyd and Reynolds, ABR) theory can be up to one-half that obtained directly from the electron current at the plasma potential. The reduction in the ion current is attributed to orbital motion (OM) of the ions and also to a small number of ion-neutral collisions in the presheath. We show that if a sufficiently large probe is chosen so as to minimize the OM effects then the collisional theory developed by Shih and Levi (1971) can be used to give an appropriate correction factor over a narrow pressure range. The corrected electron density is found to agree with the knee current value to typically 10% for Ar, N2 and Kr plasmas.

  5. Evaluation of ADCP backscatter inversion to suspended sediment concentration in estuarine environments

    NASA Astrophysics Data System (ADS)

    Lee, G. H.; Park, H. B.

    2014-12-01

    Acoustic Doppler Current Profiler (ADCP), designed for measuring velocity profile, is now widely used for the estimation of suspended sediment concentration from acoustic backscatter intensity, but its application to estuarine environments has not been vigorously tested. In this study, we examined the inversion capability of two ADCPs with 600 and 1200 kHz at three Korean estuaries: macrotidal Han river estuary (HRE), microtidal Nakdong river estuary (NRE), and anthropogenically altered macrotidal Yeongsan river estuary (YRE). In particular, we examined the relative importance of the sound attenuations due to water (aw) and sediment (as) in response to sediment characteristics (size and concentration) as well as changing salinity and temperature. The inverted concentration was compared with reference concentrations obtained either water samples or Optical Backscatter Sensors. In NRE and YRE, where suspended sediment concentrations were smaller than 0.2 kg/m3, the acoustic inversion performed poorly only with as (R2 = 0.05 and 0.39 for NRE and YRE, respectively), but well with aw (R2 = 0.70 and 0.64 for NRE and YRE, respectively). Thus, it is important to accurately constrain aw in low-concentration estuarine environments. However, we did not find that the varying aw performed considerably better than the constant aw. On the other hand, the acoustic inversion was poorest at HRE regardless of aw and as (R2 = 0.58 and mean relative error =45%). The large discrepancy appears to result from the poorly constrained, spatially and temporally varying sediment characteristics (grain size, density and concentration) due to non-local sediment transport at macrotidal HRE.

  6. Evaluation of ADCP backscatter inversion to suspended sediment concentration in estuarine environments

    NASA Astrophysics Data System (ADS)

    Lee, Guan-hong; Park, Hyo-Bong

    2015-04-01

    Acoustic Doppler Current Profiler (ADCP), designed for measuring velocity profile, is now widely used for the estimation of suspended sediment concentration from acoustic backscatter strength, but its application to estuarine environments has still room for improvement. In this study, we examinedthe inversion capability of two ADCPs with 600 and 1200 kHz at three Korean estuaries: macrotidalHan river estuary (HRE), microtidalNakdong river estuary (NRE), and anthropogenically altered macrotidalYeongsan river estuary (YRE). In particular, we examined the relative importance of the sound attenuations due to water (αw) and sediment (αs) in response to sediment characteristics (size and concentration) as well as changing salinity and temperature. The inverted concentration was compared with reference concentrations obtained either water samples or Optical Backscatter Sensors. In NRE and YRE, where suspended sediment concentrations were smaller than 0.2 g/l, the acoustic inversion performed poorly only with αs (r = 0.20and 0.38for NRE and YRE, respectively), but well with αw (r = 0.66and 0.42 for NREand YRE, respectively). Thus, it is important to accurately constrain αw in low-concentration estuarine environments. However, we did not find that the varying αw performed considerably better than the constant αw. On the other hand, the acoustic inversion was poorest at HRE regardless of αw and αs (r = 0.71 and mean relative error =45%). The large discrepancy appears to result from the poorly constrained, spatially and temporally varying sediment characteristics (grain size, density and concentration) due to non-local sediment transport at macrotidal HRE.

  7. Evaluation of ADCP backscatter inversion to suspended sediment concentration in estuarine environments

    NASA Astrophysics Data System (ADS)

    Park, Hyo-Bong; Lee, Guan-hong

    2016-03-01

    Acoustic Doppler Current Profilers (ADCP), designed for measuring velocity profiles, are widely used for the estimation of suspended sediment concentration from acoustic backscatter strength, but its application to estuarine environments requires further refinement. In this study, we examined the inversion capability of two ADCPs with 600 and 1200 kHz in three Korean estuaries: the supra-macrotidal Han River Estuary (HRE), microtidal Nakdong River Estuary (NRE), and anthropogenically altered macrotidal Yeongsan River Estuary (YRE). In particular, we examined the relative importance of the sound attenuations due to water (αw) and sediment (αs) in response to sediment characteristics (size and concentration) as well as changing salinity and temperature. The inverted concentration was compared with reference concentrations obtained either from water samples or Optical Backscatter Sensors. In NRE and YRE, where suspended sediment concentrations were less than 0.2 g/l, the acoustic inversion performed poorly only with αs (r = 0.20 and 0.38 for NRE and YRE, respectively), but well with αw (r = 0.66 and 0.42 for NRE and YRE, respectively). Thus, it is important to accurately constrain αw in low-concentration estuarine environments. However, we did not find that the varying αw performed considerably better than the constant αw. On the other hand, the acoustic inversion was poorest at HRE regardless of αw and αs (r = 0.71 and mean relative error = 45%). The large discrepancy appears to result from the poorly constrained, spatially and temporally varying sediment characteristics (grain size, density and concentration) due to non-local sediment transport in the macrotidal HRE.

  8. Impact of submergence on parshall flume discharge measurements in low gradient headwater streams

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accurate discharge measurements are critical to hydrologic design, water quality loading calculations, and rainfall/runoff studies. Generally measurement devices such as flumes and/or weirs are fabricated or commercially available and installed to facilitate discharge measurements. Development of st...

  9. River Discharge and Bathymetry Estimation from Hydraulic Inversion of Surface Currents and Water Surface Elevation Observations

    NASA Astrophysics Data System (ADS)

    Simeonov, J.; Holland, K. T.

    2015-12-01

    We developed an inversion model for river bathymetry and discharge estimation based on measurements of surface currents, water surface elevation and shoreline coordinates. The model uses a simplification of the 2D depth-averaged steady shallow water equations based on a streamline following system of coordinates and assumes spatially uniform bed friction coefficient and eddy viscosity. The spatial resolution of the predicted bathymetry is related to the resolution of the surface currents measurements. The discharge is determined by minimizing the difference between the predicted and the measured streamwise variation of the total head. The inversion model was tested using in situ and remote sensing measurements of the Kootenai River east of Bonners Ferry, ID. The measurements were obtained in August 2010 when the discharge was about 223 m3/s and the maximum river depth was about 6.5 m. Surface currents covering a 10 km reach with 8 m spatial resolution were estimated from airborne infrared video and were converted to depth-averaged currents using acoustic Doppler current profiler (ADCP) measurements along eight cross-stream transects. The streamwise profile of the water surface elevation was measured using real-time kinematic GPS from a drifting platform. The value of the friction coefficient was obtained from forward calibration simulations that minimized the difference between the predicted and measured velocity and water level along the river thalweg. The predicted along/cross-channel water depth variation was compared to the depth measured with a multibeam echo sounder. The rms error between the measured and predicted depth along the thalweg was found to be about 60cm and the estimated discharge was 5% smaller than the discharge measured by the ADCP.

  10. Screening-level estimates of mass discharge uncertainty from point measurement methods

    EPA Science Inventory

    The uncertainty of mass discharge measurements associated with point-scale measurement techniques was investigated by deriving analytical solutions for the mass discharge coefficient of variation for two simplified, conceptual models. In the first case, a depth-averaged domain w...

  11. Flood discharge measurement of a mountain river - Nanshih River in Taiwan

    NASA Astrophysics Data System (ADS)

    Chen, Y.-C.

    2013-05-01

    This study proposes a more efficient method of flood discharge measurement in mountain rivers that accounts for personal safety, accuracy, and reliability. Because it is based on the relationships between mean and maximum velocities and between cross-sectional area and gauge height, the proposed method utilizes a flood discharge measurement system composed of an acoustic Doppler profiler and crane system to measure velocity distributions, cross-sectional area, and water depths. The flood discharge measurement system can be used to accurately and quickly measure flood data that is difficult to be collected by the conventional instruments. The measured data is then used to calibrate the parameters of the proposed method for estimating mean velocity and cross-sectional area. Then these observed discharge and gauge height can be used to establish the water stage-discharge rating curve. Therefor continuous and real-time estimations of flood discharge of a mountain river can become possible. The measurement method and system is applied to the Nanshih River at the Lansheng Bridge. Once the method is established, flood discharge of the Nanshih River could be efficiently estimated using maximum velocity and the water stage. Results of measured and estimated discharges of the Nanshih River at the Lansheng Bridge differed only slightly from each other, demonstrating the efficiency and accuracy of the proposed method.

  12. ADCP-based Deep-water Current Velocity Structure and Suspended Sediment Distribution in the Northeastern South China Sea

    NASA Astrophysics Data System (ADS)

    Zhao, Y.; Liu, Z.; Zhang, Y.; Wang, W.; Li, J.; Xu, J.

    2013-12-01

    A downward-looking ADCP (acoustic doppler current profiler) was deployed in the northeastern South China Sea, near the Dongsha Islands, for 20 months (Sept. 2011 to Apr. 2013). The ADCP measures current velocity in the depth range of 1700-2100 m (0-400 m above seafloor). The relative backscatter coefficients (Sv) calculated from echo intensities of the ADCP are employed to estimate distribution patterns of suspended particles in the deep-water column of the region. The subtidal currents (PL33 low-pass filtered) in the depth range of 1700-2100 m generally flow southwestwards, with average speeds of 2-4 cm/s. However, bursts of strong currents with a speed as high as 11 cm/s throughout the observed water column (1700-2100 m) occurred several times during the 20-months period. These strong current events were in general followed by reversals of current directions (from southwestward to northeastward) whose recurrence interval appears to be in accordance with the length of strong current events. Elevated current speeds were also found in part, either upper or lower, of the observed water column, but these 'partial' events were usually not followed by a current reversal. During Mar. to Aug. 2012, a southwestward tongue-shaped high-velocity layer, which was probably linked to invasion of the North Pacific Deep Water, was observed in the depth range of 1750-2050 m, i.e. 50-350 m above seafloor, with the largest current velocity observed at ~200 m above seafloor. The Sv values were highest near the seafloor and decreased gradually upwards, forming pulse-like high sediment concentration events. Statistically, the high sediment-concentration events were related neither to the elevated current speed events nor to the current reversals.

  13. Developments in the SediView Technique for the processing of ADCP backscatter data to extract suspended sediment concentration profiles in flocculated sediments

    NASA Astrophysics Data System (ADS)

    Taylor, Jon; Manning, Andrew; Crossouard, Neil

    2014-05-01

    From its appearance in the 1980's researchers have recognised the possibilities offered by Acoustic Doppler Current Profiler's (ADCP's) as a means of obtaining information on fluid motion and concentration profiles in both muddy and sandy environments. To date much research effort has been directed in using ADCP's to indirectly observe variations in sandy sediments in suspension using the intensity of the backscattered energy returned from an ADCP and indeed to applications involving mixed suspensions of Sandy and Silty sediments. Studies of naturally flocculating sediment suspensions have however been limited due to practical difficulties in obtaining measurements of floc properties and the incomplete understanding of the interaction taking place between high frequency sound waves and the flocculated particles whilst those that are available have tended to be based on academic studies utilising multi-frequency acoustic sensors rather than the more ubiquitous Acoustic Doppler profilers used in commercial marine monitoring applications and hence their findings are limited in their application. In response to the need to provide water column concentration estimates for engineering applications the Sediview™ method was developed as a means of analysing acoustic backscatter data collected using standard ADCP profilers by means of a robust field methodology supported by software tools and the approach been applied to datasets collected in estuarine and fluvial environments worldwide through it's application on dredging and maritime engineering projects. The poster describes the application of Sediview™ methodology to the application of determining sediment concentration estimates from flocculated sediments measured at a site located within the Turbidity Maximum Zone of the Thames Estuary, UK, and in particular the application of a dual frequency approach to the problem. The experimental investigations described focused on the Acoustic backscatter from ADCPs

  14. BABE - a brush cathode discharge for thermal fluctuation measurements

    NASA Astrophysics Data System (ADS)

    Ratynskaia, S.; Dilecce, G.; Tolias, P.

    2015-04-01

    For experimental tests of fluctuation theory in ideal plasmas and plasmas seeded with dust, the ideal environment would be that of stable quiescent plasma. In most laboratory plasmas the homogeneous state of the positive column is often unstable, rare exceptions are the so-called brush cathode discharges, proposed in the 60s, where a specially manufactured cathode allows stable operation in the abnormal glow regime and the only fluctuations present are those due the thermal motion of the particles. Such a device, the BAri Brush Electrode (BABE), has recently been built in a novel configuration that combines the advantages of the inverse design with those of the reflex geometry. The region between the two anodes is essentially field-free and extremely stable in wide range of plasma densities and collisionalities. Unprecedented low fluctuation levels of δn/n <= 10-5 in He and δn/n <= 5 × 10-6 in Ar discharges have been achieved.

  15. Comparative Study of Electric Field Measurement in Glow Discharges using Laser Optogalvanic Spectroscopy

    SciTech Connect

    Hussain, Shahid; Saleem, M.; Baig, M. A.

    2008-10-22

    The net electric field inside low-pressure glow discharges has been measured using laser optogalvanic spectroscopy of 1s2s {sup 1}S{sub 0}{yields}np{sup 1}P{sub 1} Rydberg series of atomic helium. Three different types of discharges, an inductively coupled RF discharge cell operating at 4 MHz, a homemade DC discharge cell and a commercial see-through hollow cathode lamp have been used for these studies. The Rydberg series terminates earlier in the high electric field discharge as compared to that in the low electric field discharge. The net electric field also produces shift and broadens the observed spectral lines especially in the high lying Rydberg transitions. The electric field has been determined from the series termination and also from the energy shift of the observed transitions.

  16. Estimating stream discharge using stage and multi-level acoustic Doppler velocimetry

    NASA Astrophysics Data System (ADS)

    Poulsen, J. B.; Rasmussen, K.; Ledet Jensen, J.; Bering Ovesen, N.

    2011-12-01

    and stage data to discharge will be presented. The estimated discharges are compared with control measurements of discharge obtained from an Acoustic Doppler Current Profiler (ADCP) and with discharge values derived by the Danish Water Authority by traditional stage-discharge analysis. The novelty of this approach is that the velocity gradient is implemented as a marker for hydraulic changes in the hydrograph estimation, without explicit use of cross sectional area and cross sectional average velocity. The initial results show good agreement between the ADCP discharge measurements and the discharge values predicted from the stage-velocity method and suggest superiority of the stage-velocity method during abrupt changes in stage.

  17. Discharge-measurement system using an acoustic Doppler current profiler with applications to large rivers and estuaries

    USGS Publications Warehouse

    Simpson, Michael R.; Oltmann, Richard N.

    1993-01-01

    Discharge measurement of large rivers and estuaries is difficult, time consuming, and sometimes dangerous. Frequently, discharge measurements cannot be made in tide-affected rivers and estuaries using conventional discharge-measurement techniques because of dynamic discharge conditions. The acoustic Doppler discharge-measurement system (ADDMS) was developed by the U.S. Geological Survey using a vessel-mounted acoustic Doppler current profiler coupled with specialized computer software to measure horizontal water velocity at 1-meter vertical intervals in the water column. The system computes discharge from water-and vessel-velocity data supplied by the ADDMS using vector-algebra algorithms included in the discharge-measurement software. With this system, a discharge measurement can be obtained by engaging the computer software and traversing a river or estuary from bank to bank; discharge in parts of the river or estuarine cross sections that cannot be measured because of ADDMS depth limitations are estimated by the system. Comparisons of ADDMS-measured discharges with ultrasonic-velocity-meter-measured discharges, along with error-analysis data, have confirmed that discharges provided by the ADDMS are at least as accurate as those produced using conventional methods. In addition, the advantage of a much shorter measurement time (2 minutes using the ADDMS compared with 1 hour or longer using conventional methods) has enabled use of the ADDMS for several applications where conventional discharge methods could not have been used with the required accuracy because of dynamic discharge conditions.

  18. Overview of hydro-acoustic current-measurement applications by the U.S. geological survey in Indiana

    USGS Publications Warehouse

    Morlock, Scott E.; Stewart, James A.

    1999-01-01

    The U.S. Geological Survey (USGS) maintains a network of 170 streamflow-gaging stations in Indiana to collect data from which continuous records of river discharges are produced. Traditionally, the discharge record from a station is produced by recording river stage and making periodic discharge measurements through a range of stage, then developing a relation between stage and discharge. Techniques that promise to increase data collection accuracy and efficiency include the use of hydro-acoustic instrumentation to measure river velocities. The velocity measurements are used to compute river discharge. In-situ applications of hydro-acoustic instruments by the USGS in Indiana include acoustic velocity meters (AVM's) at six streamflow-gaging stations and newly developed Doppler velocity meters (DVM's) at two stations. AVM's use reciprocal travel times of acoustic signals to measure average water velocities along acoustic paths, whereas DVM's use the Doppler shift of backscattered acoustic signals to compute water velocities. In addition to the in-situ applications, three acoustic Doppler current profilers (ADCP's) are used to make river-discharge measurements from moving boats at streamflow-gaging stations in Indiana. The USGS has designed and is testing an innovative unmanned platform from which to make ADCP discharge measurements.

  19. Regression models of discharge and mean velocity associated with near-median streamflow conditions in Texas: utility of the U.S. Geological Survey discharge measurement database

    USGS Publications Warehouse

    Asquith, William H.

    2014-01-01

    A database containing more than 16,300 discharge values and ancillary hydraulic attributes was assembled from summaries of discharge measurement records for 391 USGS streamflow-gauging stations (streamgauges) in Texas. Each discharge is between the 40th- and 60th-percentile daily mean streamflow as determined by period-of-record, streamgauge-specific, flow-duration curves. Each discharge therefore is assumed to represent a discharge measurement made for near-median streamflow conditions, and such conditions are conceptualized as representative of midrange to baseflow conditions in much of the state. The hydraulic attributes of each discharge measurement included concomitant cross-section flow area, water-surface top width, and reported mean velocity. Two regression equations are presented: (1) an expression for discharge and (2) an expression for mean velocity, both as functions of selected hydraulic attributes and watershed characteristics. Specifically, the discharge equation uses cross-sectional area, water-surface top width, contributing drainage area of the watershed, and mean annual precipitation of the location; the equation has an adjusted R-squared of approximately 0.95 and residual standard error of approximately 0.23 base-10 logarithm (cubic meters per second). The mean velocity equation uses discharge, water-surface top width, contributing drainage area, and mean annual precipitation; the equation has an adjusted R-squared of approximately 0.50 and residual standard error of approximately 0.087 third root (meters per second). Residual plots from both equations indicate that reliable estimates of discharge and mean velocity at ungauged stream sites are possible. Further, the relation between contributing drainage area and main-channel slope (a measure of whole-watershed slope) is depicted to aid analyst judgment of equation applicability for ungauged sites. Example applications and computations are provided and discussed within a real-world, discharge-measurement

  20. Multi-frequency acoustic derivation of particle size using 'off-the-shelf" ADCPs.

    NASA Astrophysics Data System (ADS)

    Haught, D. R.; Wright, S. A.; Venditti, J. G.; Church, M. A.

    2015-12-01

    Suspended sediment particle size in rivers is of great interest due to its influence on riverine and coastal morphology, socio-economic viability, and ecological health and restoration. Prediction of suspended sediment transport from hydraulics remains a stubbornly difficult problem, particularly for the washload component, which is controlled by sediment supply from the drainage basin. This has led to a number of methods for continuously monitoring suspended sediment concentration and mean particle size, the most popular currently being hydroacoustic methods. Here, we explore the possibility of using theoretical inversion of the sonar equation to derive an estimate of mean particle size and standard deviation of the grain size distribution (GSD) using three 'off-the-shelf' acoustic Doppler current profiles (ADCP) with frequencies of 300, 600 and 1200 kHz. The instruments were deployed in the sand-bedded reach of the Fraser River, British Columbia. We use bottle samples collected in the acoustic beams to test acoustics signal inversion methods. Concentrations range from 15-300 mg/L and the suspended load at the site is ~25% sand, ~75 % silt/clay. Measured mean particle radius from samples ranged from 10-40 microns with relative standard deviations ranging from 0.75 to 2.5. Initial results indicate the acoustically derived mean particle radius compares well with measured particle radius, using a theoretical inversion method adapted to the Fraser River sediment.

  1. Book 1: Hydraulic measurement and computation, Chapter 16: Use of flumes in measuring discharge at gaging stations

    USGS Publications Warehouse

    Kilpatrick, F.A.

    1965-01-01

    This report discusses the general principles underlying the design of various types of flumes for measuring open-channel flow. Four flumes are described in detail, and the recommended discharge ratings for each are presented.

  2. [Study on the discharge properties of xeon flash lamp and experimental measurement].

    PubMed

    Zhao, You-Quan; Miao, Pei-Liang; He, Feng; Gu, Jian; Zhai, Rui-Wei

    2014-07-01

    The Xenon flash lamp is a new type of light source for analytical instrument. The present paper analyzed the discharge process of xenon flash lamp, presented the discharge test system, and conducted experimental measurement of the voltage, current and optical pulse signal in the process of discharge. The results show that in the preliminary discharge, the free electron concentration was at a low level, so the energy was at a low level, then following the gas discharge, numerous free electrons formed in the lamp, resultin in the increase in the concentration of free electrons, therefore discharge current rised rapidly and voltage reduced. The lamp released photons to generate light pulse in the moment of ionic recombination, The pulse xenon lamp light energy output and spectral characteristic is related to electron energy in recombination and combination level of xenon, if the input energy and the energy consumption of the xenon lamp is inconsistent, it will lead to repeated capacitor charging and discharging and produce oscillation waveform. This paper is very useful for understanding the process of xenon lamp discharge, optimizing the driver circuit and the production of xenon flash lamp. PMID:25269320

  3. Effects of non-homogeneous flow on ADCP data processing in a hydroturbine forebay

    DOE PAGESBeta

    Harding, S. F.; Richmond, M. C.; Romero-Gomez, P.; Serkowski, J. A.

    2016-01-02

    Accurate modeling of the velocity field in the forebay of a hydroelectric power station is important for both power generation and fish passage, and is able to be increasingly well represented by computational fluid dynamics (CFD) simulations. Acoustic Doppler Current Profiler (ADCP) are investigated herein as a method of validating the numerical flow solutions, particularly in observed and calculated regions of non-homogeneous flow velocity. By using a numerical model of an ADCP operating in a velocity field calculated using CFD, the errors due to the spatial variation of the flow velocity are quantified. Furthermore, the numerical model of the ADCPmore » is referred to herein as a Virtual ADCP (VADCP).« less

  4. Application of acoustic doppler current profilers for measuring three-dimensional flow fields and as a surrogate measurement of bedload transport

    USGS Publications Warehouse

    Conaway, J.S.

    2005-01-01

    Acoustic Doppler current profilers (ADCPs) have been in use in the riverine environment for nearly 20 years. Their application primarily has been focused on the measurement of streamflow discharge. ADCPs emit high-frequency sound pulses and receive reflected sound echoes from sediment particles in the water column. The Doppler shift between transmitted and return signals is resolved into a velocity component that is measured in three dimensions by simultaneously transmitting four independent acoustical pulses. To measure the absolute velocity magnitude and direction in the water column, the velocity magnitude and direction of the instrument must also be computed. Typically this is accomplished by ensonifying the streambed with an acoustical pulse that also provides a depth measurement for each of the four acoustic beams. Sediment transport on or near the streambed will bias these measurements and requires external positioning such as a differentially corrected Global Positioning Systems (GPS). Although the influence of hydraulic structures such as spur dikes and bridge piers is typically only measured and described in one or two dimensions, the use of differentially corrected GPS with ADCPs provides a fully three-dimensional measurement of the magnitude and direction of the water column at such structures. The measurement of these flow disturbances in a field setting also captures the natural pulsations of river flow that cannot be easily quantified or modeled by numerical simulations or flumes. Several examples of measured three-dimensional flow conditions at bridge sites throughout Alaska are presented. The bias introduced to the bottom-track measurement is being investigated as a surrogate measurement of bedload transport. By fixing the position of the ADCP for a known period of time the apparent velocity of the streambed at that position can be determined. Initial results and comparison to traditionally measured bedload values are presented. These initial

  5. Time-resolved measurement of pressure evolution in underwater nanosecond discharge

    NASA Astrophysics Data System (ADS)

    Marinov, Ilya; Guaitella, Olivier; Starikovskaia, Svetlana; Rousseau, Antoine

    2012-10-01

    Electrical discharges in water and other dielectric liquids have been extensively studied since almost fifty years, however reliable data on plasma parameters within the propagation phase is still missing. We report on shadowgraphic imaging and optical emission spectroscopy (OES) both with nanosecond time resolution of pulsed nanosecond discharge generated with point to wire electrode configuration. High voltage pulses of 10 kV and 30 ns duration (FWHM) are delivered by commercial pulse generator FPG 10 (FIG GmbH). Sub-millimeter discharge with filamentary structure develops at 50 km/s in axial direction of pin electrode. Using Hugoniot equations maximal discharge pressure at ignition can be obtained from shock wave front velocity. Analytical model of supersonic cavity expansion based on Kirkwood-Bethe approximation gives discharge pressure evolution from experimentally measured discharge channel expansion velocity profile. Thus, the pressure of 5 GPa is measured at the discharge ignition and drops drastically by the end of voltage pulse. Time-resolved OES spectrum shows a strong broadening of atomic Hydrogen (Balmer series) and oxygen (OI 777 nm) lines with almost continuum emission in the region 300-700 nm. Complex Hα and OI 777 profiles are due to combined contribution of Van Der Waals and Stark broadening. Electronic density can be deduced from lorentzian fit of Stark broadening and gives for electronic density 10^24 - 10^25 m-3.

  6. Small-signal gain diagnostic measurements in a flowing CO2 pin discharge laser

    NASA Technical Reports Server (NTRS)

    Blech, R. A.; Manista, E. J.; Dunning, J. W., Jr.

    1977-01-01

    Small-signal gain diagnostic measurements were conducted on closed loop, high power, carbon dioxide laser to assess the coupling between gas flow velocity and resonator saturation. Parameters investigated included optical cavity and discharge power. Results of gain measurements within and downstream of the excitation volume are presented for a laser gas composition He:N2:CO2 of 10:7:1 at 90 torr. The gain at constant discharge power was observed to be dependent upon discharge power level and time. An important result of this study is that the effects of gain swept downstream of the discharge region must be considered in the resonator design if efficient extraction of stored optical energy is desired.

  7. RF discharge impedance measurements using a new method to determine the stray impedances

    SciTech Connect

    Bakker, L.P.; Kroesen, G.M.W.; Hoog, F.J. de )

    1999-06-01

    The impedance of a capacitively coupled radio frequency discharge in a tubular fluorescent lamp filled with neon and mercury is measured. The stray impedances in the electrical network are determined using a new method that requires no extra instruments. The reflection of power is used to determine the stray impedances. Making use of a simple discharge impedance model, the electron density in the lamp is estimated.

  8. Adaptive method for quantifying uncertainty in discharge measurements using velocity-area method.

    NASA Astrophysics Data System (ADS)

    Despax, Aurélien; Favre, Anne-Catherine; Belleville, Arnaud

    2015-04-01

    Streamflow information provided by hydrometric services such as EDF-DTG allow real time monitoring of rivers, streamflow forecasting, paramount hydrological studies and engineering design. In open channels, the traditional approach to measure flow uses a rating curve, which is an indirect method to estimate the discharge in rivers based on water level and punctual discharge measurements. A large proportion of these discharge measurements are performed using the velocity-area method; it consists in integrating flow velocities and depths through the cross-section [1]. The velocity field is estimated by choosing a number m of verticals, distributed across the river, where vertical velocity profile is sampled by a current-meter at ni different depths. Uncertainties coming from several sources are related to the measurement process. To date, the framework for assessing uncertainty in velocity-area discharge measurements is the method presented in the ISO 748 standard [2] which follows the GUM [3] approach. The equation for the combined uncertainty in measured discharge u(Q), at 68% level of confidence, proposed by the ISO 748 standard is expressed as: Σ 2 2 2 -q2i[u2(Bi)+-u2(Di)+-u2p(Vi)+-(1ni) ×-[u2c(Vi)+-u2exp(Vi)

  9. Measuring stream discharge by non-contact methods: A proof-of-concept experiment

    USGS Publications Warehouse

    Costa, J.E.; Spicer, K.R.; Cheng, R.T.; Haeni, F.P.; Melcher, N.B.; Thurman, E.M.; Plant, W.J.; Keller, W.C.

    2000-01-01

    This report describes an experiment to make a completely non-contact open-channel discharge measurement. A van-mounted, pulsed doppler (10GHz) radar collected surface-velocity data across the 183-m wide Skagit River, Washington at a USGS streamgaging station using Bragg scattering from short waves produced by turbulent boils on the surface of the river. Surface velocities were converted to mean velocities for 25 sub-sections by assuming a normal open-channel velocity profile (surface velocity times 0.85). Channel cross-sectional area was measured using a 100 MHz ground-penetrating radar antenna suspended from a cableway car over the river. Seven acoustic doppler current profiler discharge measurements and a conventional current-meter discharge measurement were also made. Three non-contact discharge measurements completed in about a 1-hour period were within 1 % of the gaging station rating curve discharge values. With further refinements, it is thought that open-channel flow can be measured reliably by non-contact methods.

  10. Measurement of Turbulence with Acoustic Doppler Current Profilers - Sources of Error and Laboratory Results

    USGS Publications Warehouse

    Nystrom, E.A.; Oberg, K.A.; Rehmann, C.R.

    2002-01-01

    Acoustic Doppler current profilers (ADCPs) provide a promising method for measuring surface-water turbulence because they can provide data from a large spatial range in a relatively short time with relative ease. Some potential sources of errors in turbulence measurements made with ADCPs include inaccuracy of Doppler-shift measurements, poor temporal and spatial measurement resolution, and inaccuracy of multi-dimensional velocities resolved from one-dimensional velocities measured at separate locations. Results from laboratory measurements of mean velocity and turbulence statistics made with two pulse-coherent ADCPs in 0.87 meters of water are used to illustrate several of inherent sources of error in ADCP turbulence measurements. Results show that processing algorithms and beam configurations have important effects on turbulence measurements. ADCPs can provide reasonable estimates of many turbulence parameters; however, the accuracy of turbulence measurements made with commercially available ADCPs is often poor in comparison to standard measurement techniques.

  11. Thrust Measurement of Dielectric Barrier Discharge (DBD) Plasma Actuators

    NASA Astrophysics Data System (ADS)

    Ashpis, David E.; Laun, Matthew C.

    2013-11-01

    DBD plasma actuators generate a wall-jet that can be used for active flow control. We used an analytical balance to measure the thrust generated by the actuator, it is a common metric of its performance without external flow. We found that the measured force is afflicted by several problems; it drifts in time, not always repeatable, is unstable, and depends on the manner the voltage is applied. We report results of investigations of these issues. Tests were conducted on an actuator constructed of 1/4 inch thick high-density polyethylene (HDPE) dielectric with 100 mm long offset electrodes, with applied voltages up to 48 kV p-p and frequencies from 32 Hz to 2.5 kHz, and pure Sine and Trapezoidal waveforms. The relative humidity was in the range of 51-55%, corresponding to moisture range of 10,500 to13,000 ppm mass. Force readings were up to 500 mg, (approximately 50 mN/m). We found that the measured force is the net of the positive thrust generated by the wall-jet and an ``anti-thrust'' acting in the opposite direction. We propose a correction procedure that yields the plasma-generated thrust. The correction is based on voltage-dependent anti-thrust measured in the low frequency range of 20-40 Hz. We found that adjacent objects in a test setup affect the measured thrust, and verified it by comparing experiments with and without a metal enclosure, grounded and ungrounded. Uncorrected thrust varied by up to approximately +/-100%, and the corrected thrust variations were up to approximately 30%. Supported by NASA's FAP/Aerospace Sciences Project.

  12. Ground-penetrating radar methods used in surface-water discharge measurements

    USGS Publications Warehouse

    Haeni, F.P.; Buursink, Marc L.; Costa, John E.; Melcher, Nick B.; Cheng, Ralph T.; Plant, William J.

    2000-01-01

    In 1999, an experiment was conducted to see if a combination of complementary radar methods could be used to calculate the discharge of a river without having any of the measuring equipment in the water. The cross-sectional area of the 183-meter wide Skagit River in Washington State was measured using a ground-penetrating radar (GPR) system with a single 100-MHz antenna. A van-mounted, side-looking pulsed-Doppler radar system was used to collect water-surface velocity data across the same section of the river. The combined radar data sets were used to calculate the river discharge and the results compared closely to the discharge measurement made by using the standard in-water measurement techniques.

  13. Neutron spectrum measurements in DT discharges using activation techniques

    NASA Astrophysics Data System (ADS)

    Esposito, B.; Bertalot, L.; Loughlin, M.; Roquemore, A. L.

    1999-01-01

    The JET activation system has eight irradiation ends where samples may be irradiated in the neutron flux from the plasma. There is one end, re-entrant into the top of the vessel, for which there is little intervening material between it and the plasma; the other ends, including two beneath the divertor coils, have increasingly larger amounts of intervening structure. The local neutron spectrum at each irradiation end was measured by simultaneously activating several elemental foils (Al, Au, Co, Fe, In, Mg, Nb, Ni, Ti, Zr). There were 15 activation reactions in the energy range of 0.5-16 MeV which were used as input to the SNL-SAND-II code to determine the neutron energy spectrum. The results are compared with neutron transport calculations both from the MCNP and FURNACE codes: the average standard deviation between measured to SNL-SAND-II calculated activity ratios was as low as 5%. The results demonstrate the reliability of the neutronics calculations and have implications for the design of diagnostics and blankets for the next generation of large tokamaks such as ITER. The 377.9 keV line of the 54Fe(n,2n)53Fe reaction (threshold ˜13.9 MeV, not a dosimetric standard) has also been measured in different plasma conditions. The ratio of the saturated activity from this reaction to that from the 56Fe(n,p)56Mn reaction (threshold ˜4.5 MeV) provides information on the broadening of the 14 MeV fusion peak.

  14. 46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Cargo viscosity and melting point information; measuring... Cargo viscosity and melting point information; measuring cargo temperature during discharge: Categories... lading, a written statement of the following: (1) For Category A or B NLS, the cargo's viscosity at 20...

  15. 46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Cargo viscosity and melting point information; measuring... Cargo viscosity and melting point information; measuring cargo temperature during discharge: Categories... lading, a written statement of the following: (1) For Category A or B NLS, the cargo's viscosity at 20...

  16. 46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Cargo viscosity and melting point information; measuring... Cargo viscosity and melting point information; measuring cargo temperature during discharge: Categories... lading, a written statement of the following: (1) For Category A or B NLS, the cargo's viscosity at 20...

  17. 46 CFR 153.908 - Cargo viscosity and melting point information; measuring cargo temperature during discharge...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Cargo viscosity and melting point information; measuring... Cargo viscosity and melting point information; measuring cargo temperature during discharge: Categories... lading, a written statement of the following: (1) For Category A or B NLS, the cargo's viscosity at 20...

  18. The Uncertainty of Mass Discharge Measurements Using Pumping Methods Under Simplified Conditions

    EPA Science Inventory

    Mass discharge measurements at contaminated sites have been used to assist with site management decisions, and can be divided into two broad categories: point-scale measurement techniques and pumping methods. Pumping methods can be sub-divided based on the pumping procedures use...

  19. Measurement of total ion flux in vacuum Arc discharges

    SciTech Connect

    Anders, Andre; Oks, Efim M.; Yushkov, Georgy Yu.; Brown, Ian G.

    2004-04-12

    A vacuum arc ion source was modified allowing us to collections from arc plasma streaming through an anode mesh. The mesh had ageometric transmittance of 60 percent, which was taken into account as acorrection factor. The ion current from twenty-two cathode materials wasmeasured at an arc current of 100 A. The ion current normalized by thearc current was found to depend on the cathode material, with valuesinthe range from 5 percent to 11 percent. The normalized ion current isgenerally greater for light elements than for heavy elements. The ionerosion rates were determined fromvalues of ion currentand ion chargestates, which were previously measured in the same experimental system.The ion erosion rates range from 12-94 mu g/C.

  20. Effect of Electron Seeding on Experimentally Measured Multipactor Discharge Threshold

    NASA Astrophysics Data System (ADS)

    Noland, Jonathan; Graves, Timothy; Lemon, Colby; Looper, Mark; Farkas, Alex

    2012-10-01

    Multipactor is a vacuum phenomenon in which electrons, moving in resonance with an externally applied electric field, impact material surfaces. If the number of secondary electrons created per primary electron impact averages more than unity, the resonant interaction can lead to an electron avalanche. Multipactor is a generally undesirable phenomenon, as it can cause local heating, absorb power, or cause detuning of RF circuits. In order to increase the probability of multipactor initiation, test facilities often employ various seeding sources such as radioactive sources (Cesium 137, Strontium 90), electron guns, or photon sources. Even with these sources, the voltage for multipactor initiation is not certain as parameters such as material type, RF pulse length, and device wall thickness can all affect seed electron flux and energy in critical gap regions, and hence the measured voltage threshold. This study investigates the effects of seed electron source type (e.g., photons versus beta particles), material type, gap size, and RF pulse length variation on multipactor threshold. In addition to the experimental work, GEANT4 simulations will be used to estimate the production rate of low energy electrons (< 5 keV) by high energy electrons and photons. A comparison of the experimental fluxes to the typical energetic photon and particle fluxes experienced by spacecraft in various orbits will also be made. Initial results indicate that for a simple, parallel plate device made of aluminum, there is no threshold variation (with seed electrons versus with no seed electrons) under continuous-wave RF exposure.

  1. Langmuir probe measurements of double-layers in a pulsed discharge

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Crawford, F. W.

    1980-01-01

    Langmuir probe measurements were carried out which confirm the occurrence of double-layers in an argon positive column. Pulsing the discharge current permitted probe measurements to be performed in the presence of the double-layer. Supplementary evidence, obtained from DC and pulsed discharges, indicated that the double-layers formed in the two modes of operation were similar. The double-layers observed were weak and stable; their relation to other classes of double-layers are discussed, and directions for future work are suggested.

  2. Laser electric field measurement in open-air dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Ito, Tsuyohito; Kanazawa, Tatsuya; Hamaguchi, Satoshi

    2011-10-01

    Electric field induced coherent Raman scattering (E-CRS) measurement is a promising technique for measuring electric field in high-pressure environments. In this study, the discharge initiation mechanism of nanosecond dielectric barrier discharges (DBDs) in open air has been examined with time dependent measurement of the discharge electric field by E-CRS. Two pulsed ns laser beams (532 nm and 607 nm) are employed. In the presence of nitrogen molecules the two laser beams together with the electric field induce a coherent IR signal at a wavelength of 4.29 μm and the normal coherent anti-Stokes Raman scattering (CARS) signal at 473 nm. The ratio of these two signals (IR and CARS) is a function of the electric field strength, so that the magnitude of the electric field can be estimated. Our experimental observations have revealed that, in the pre-breakdown phase of a nanosecond DBD discharge, the externally applied fast-rising electric field is strongly enhanced near the cathode due to large accumulation of space charge, which then strongly enhances ionization near the cathode. This process is essentially different from the well-known Townsend mechanism for slower discharges.

  3. Probe measurements of hydrogen fluxes during discharge cleaning in JFT-2M

    NASA Astrophysics Data System (ADS)

    JFT-2M Team; Maeda, H.; Susuki, K.; Hasegawa, K.; Honda, A.; Ishibori, I.; Kashiwa, Y.; Kazawa, M.; Kikuchi, K.; Ohuchi, K.; Okano, F.; Sato, E.; Shibata, T.; Tani, T.; Uno, S.; Hoshino, K.; Kasai, S.; Kawakami, T.; Kawashima, K.; Matsuda, T.; Matsumoto, H.; Miura, Y.; Mori, M.; Nakazawa, I.; Odajima, K.; Ogawa, H.; Ogawa, T.; Ohasa, K.; Ohtsuka, H.; Sengoku, S.; Shoji, T.; Suzuki, N.; Tamai, H.; Uesugi, Y.; Yamamoto, T.; Yamauchi, T.; Matsuzaki, Y.

    1989-04-01

    Thermal desorption spectroscopy (TDS) has been applied during discharge cleaning in the JFT-2M tokamak to measure hydrogen fluxes. The TDS carbon sample, thickness 0.13 mm, was heated to 1000°C by direct current and the temperature distribution of the sample surface measured by infrared thermography. The probe was exposed to three types of plasma: Taylor-type discharge cleaning (TDC), ECR discharge cleaning (ECR-DC), and glow discharge cleaning (GDC). The TDS spectra show peak desorption at around 800°C. The hydrogen flux, obtained by integration of the TDS spectrum, decreases exponentially in the radial direction with decay length 7.4 cm and 5.8 cm in TDC and ECR-DC, respectively. The relation between hydrogen fluxes and water vapour production was investigated. In TDC, the amount of water vapour depends more strongly on the electron temperature of the plasma than on the hydrogen flux. In ECR-DC, the production of water vapour increases approximately linearly with the hydrogen-flux. In GDC, hydrogen fluxes were measured by TDS but no water vapour could be detected in the residual gases during the discharge.

  4. Electric field measurement in microwave discharge ion thruster with electro-optic probe.

    PubMed

    Ise, Toshiyuki; Tsukizaki, Ryudo; Togo, Hiroyoshi; Koizumi, Hiroyuki; Kuninaka, Hitoshi

    2012-12-01

    In order to understand the internal phenomena in a microwave discharge ion thruster, it is important to measure the distribution of the microwave electric field inside the discharge chamber, which is directly related to the plasma production. In this study, we proposed a novel method of measuring a microwave electric field with an electro-optic (EO) probe based on the Pockels effect. The probe, including a cooling system, contains no metal and can be accessed in the discharge chamber with less disruption to the microwave distribution. This method enables measurement of the electric field profile under ion beam acceleration. We first verified the measurement with the EO probe by a comparison with a finite-difference time domain numerical simulation of the microwave electric field in atmosphere. Second, we showed that the deviations of the reflected microwave power and the beam current were less than 8% due to inserting the EO probe into the ion thruster under ion beam acceleration. Finally, we successfully demonstrated the measurement of the electric-field profile in the ion thruster under ion beam acceleration. These measurements show that the electric field distribution in the thruster dramatically changes in the ion thruster under ion beam acceleration as the propellant mass flow rate increases. These results indicate that this new method using an EO probe can provide a useful guide for improving the propulsion of microwave discharge ion thrusters. PMID:23278009

  5. Electric field measurement in microwave discharge ion thruster with electro-optic probe

    SciTech Connect

    Ise, Toshiyuki; Tsukizaki, Ryudo; Koizumi, Hiroyuki; Togo, Hiroyoshi; Kuninaka, Hitoshi

    2012-12-15

    In order to understand the internal phenomena in a microwave discharge ion thruster, it is important to measure the distribution of the microwave electric field inside the discharge chamber, which is directly related to the plasma production. In this study, we proposed a novel method of measuring a microwave electric field with an electro-optic (EO) probe based on the Pockels effect. The probe, including a cooling system, contains no metal and can be accessed in the discharge chamber with less disruption to the microwave distribution. This method enables measurement of the electric field profile under ion beam acceleration. We first verified the measurement with the EO probe by a comparison with a finite-difference time domain numerical simulation of the microwave electric field in atmosphere. Second, we showed that the deviations of the reflected microwave power and the beam current were less than 8% due to inserting the EO probe into the ion thruster under ion beam acceleration. Finally, we successfully demonstrated the measurement of the electric-field profile in the ion thruster under ion beam acceleration. These measurements show that the electric field distribution in the thruster dramatically changes in the ion thruster under ion beam acceleration as the propellant mass flow rate increases. These results indicate that this new method using an EO probe can provide a useful guide for improving the propulsion of microwave discharge ion thrusters.

  6. Acoustic Doppler Current Profiler Measurements in the Tailrace at John Day Dam

    SciTech Connect

    Cook, Chris B.; Dibrani, Berhon; Serkowski, John A.; Richmond, Marshall C.; Titzler, P. Scott; Dennis, Gary W.

    2006-01-30

    measuring 1D water velocity magnitudes has been previously demonstrated by the authors, the feasibility of resolving 3D water velocity vectors given the heterogeneity of the flow field was unknown before this study’s data were collected. Both the 1D and 3D data were collected by deploying three ADCPs on dual-axis rotators directly above the draft tube exit of Turbine Unit 16. These instruments collected 1D data during both the mobile reconnaissance campaign and a later one-week period with zero spillway discharge. During the zero spillway discharge period, Turbine Unit 16 was operated over a range of discharges. Approximately 12 hours of 1D velocity data were collected at low (12 kcfs), middle (16.2 kcfs), and high (19.2 kcfs) turbine discharges. The 1D dataset indicates large differences in flow patterns and RMS velocity fluctuations among the various discharge levels. Results from this project show that it is technically feasible to measure 3D water velocities directly downstream of an operating turbine unit using a narrow beam swath (i.e., 6-degree) ADCP. Data products from these 3D velocity data include a measurement of the draft tube barrel flow distribution (a.k.a., the flow split), directional changes and the general decay of velocity as flow exits the draft tube and enters the tailrace, and a relative measure of the homogeneity of the flow field.

  7. Comparison between measured and simulated breakdown characteristics in micro discharges in argon

    NASA Astrophysics Data System (ADS)

    Petrovic, Zoran; Radmilovic-Radjenovic, Marija; Maguire, Paul; Mahony, Charles; Skoro, Nikola; Maric, Dragana

    2007-10-01

    Devices with micron and sub-micron gaps can face a serious challenge due to electrical breakdown during manufacturing, handling and operation. Therefore, it is necessary to be aware of the breakdown voltage for different gaps. Gas breakdown and Volt-Ampere characteristics are studied in an atmospheric pressure argon discharges. Experimental results are compared with the results obtained by using PIC/MCC code in order to establish whether the standard micro discharges operate in Townsend regime or in Glow Regime. The code is adjusted to include field emission effect in microgaps. It is applied manly for the breakdown stage but may also follow the formation of the space charge. The measurements of Volt-Ampere and breakdown characteristics of micro discharges were performed down to 20,μm gaps at pressures up to 400,orr. Paschen curves reveal that very tight geometry is required to avoid long path breakdown at the left hand side of the Paschen curve. It is critical to measure width of the discharge to test the scaling and regime of operation of micro discharges.

  8. An entropy-based surface velocity method for estuarine discharge measurement

    NASA Astrophysics Data System (ADS)

    Bechle, Adam J.; Wu, Chin H.

    2014-07-01

    An entropy-based method is developed to estimate estuarine river discharge from surface velocity measurements. A two-dimensional velocity profile based on the principle of maximum entropy is employed to express the mean velocity as a function of average surface velocity. The entropy-based flow profile is parameterized by the location of maximum velocity in the channel and the shape of the velocity distribution. The entropy parameters are quantified over the tidal cycle to account for the unsteady nature of estuarine flow. The method was tested using experiments conducted at the Danshui River, the largest estuarine system in Taiwan. Surface velocities were measured using an Automated River-Estuary Discharge Imaging System (AREDIS), and full-channel velocity profiles were measured with a moving-boat ADP survey. Entropy parameters were calibrated over the tidal cycle and linearly correlated with the average surface velocity to facilitate estimation from AREDIS measurements. The discharge calculated from average surface velocity and entropy relationships exhibits a 7.7% relative error compared to the ADP velocity profiles. The error nearly doubles when the mean values for entropy parameters are used instead of the variable parameters, indicating the importance of accounting for the unsteady nature of estuarine flows. Furthermore, the effects of measurement coverage area, types of entropy distribution, and wind-induced drift current on the surface velocity-based discharge measurement are evaluated and discussed. Overall, surface velocity measurements in conjunction with the entropy profiles well represent the flow in a complex estuarine environment to provide a reliable estimate of discharge.

  9. Measurement of velocities with an acoustic velocity meter, one side-looking and two upward-looking acoustic Doppler current profilers in the Chicago Sanitary and Ship Canal, Romeoville, Illinois

    USGS Publications Warehouse

    Oberg, Kevin A.; Duncker, James J.

    1999-01-01

    In 1998, a prototype 300 kHz, side-looking Acoustic Doppler Current Profiler (ADCP) was deployed in the Chicago Sanitary and Ship Canal (CSSC) at Romeoville, Illinois. Additionally, two upward-looking ADCP's were deployed in the same acoustic path as the side-looking ADCP and in the reach defined by the upstream and downstream acoustic velocity meter (AVM) paths. All three ADCP's were synchronized to the AVM clock at the gaging station so that data were sampled simultaneously. The three ADCP's were deployed for six weeks measuring flow velocities from 0.0 to 2.5 ft/s. Velocities measured by each ADCP were compared to AVM path velocities and to velocities measured by the other ADCP's.

  10. In situ transmissiometer measurements for real-time monitoring of dust discharge during orchard nut harvesting.

    PubMed

    Downey, D; Giles, D K; Thompson, J F

    2008-01-01

    Rapid assessments of operating conditions and field preparation on dust discharge from nut harvesters are needed to guide improved equipment design and grower practices for dust reduction. An industrial opacity sensor, typically used for industrial stack monitoring, was adapted for use on a nut harvester to measure relative dust intensity during nut pick-up operations in almond orchards. Due to the high volume of discharge air and the presence of large debris such as leaves, additional components were coupled with the sensor to enable subsampling of the air. Pre-harvest windrow preparation conditions were evaluated. Results indicated that relative dust intensity decreased by 32% during harvest activities after windrow preparation with proper nut sweeper adjustment. Conventional harvesting results indicated that under typical operating conditions, reducing the separation fan speed could reduce relative dust intensity by 54%. Ground speed also had a strong effect; reducing speed from 4.8 to 2.4 km h(-1) reduced opacity of discharged air by 50%. The measurement system was also mounted on a separate vehicle and used as a tool for comparing modifications in harvest machine designs where direct measurement of discharge may not be feasible due to mechanical constraints. A comparison between a conventional harvester and one modification in the harvester design found that the machine modification decreased relative dust intensity by 73%. The measurement tools described in this work can be used to provide rapid feedback on harvester operating conditions, orchard cultural practices, and machine design modifications. PMID:18396543

  11. Efficacy of syndromic management measured as symptomatic improvement in females with vaginal discharge syndrome

    PubMed Central

    Chauhan, Vidyalaxmi; Shah, Maitri C.; Patel, Sangita V.; Marfatia, Yogesh S.; Zalavadiya, Dhara

    2016-01-01

    Background: In spite of a few shortcomings such as over diagnosis and over treatment, syndromic management is a recommended practice in India for sexually transmitted infections (STIs). This study tries to find out the efficacy of syndromic management measured as symptomatic improvement in females with vaginal discharge syndrome. Objective: The objective of the study is to find out the effectiveness of syndromic management in terms of symptomatic improvement among females with vaginal discharge syndrome. Materials and Methods: A longitudinal study was conducted in Gynecology Department of Tertiary Care Hospital including 180 symptomatic females having vaginal discharge syndrome. Demographic profile, presenting complaints, menstrual history, obstetric history, partner history, and contraceptive history were noted. This was followed by clinical examination and specimen collection for laboratory tests and blood tests to find out type of STI including viral STI such as human immunodeficiency virus (HIV), herpes simplex virus (HSV), and hepatitis B surface antigen (HBsAg). Treatment was given according to syndromic management on the same day. All the participants were asked to come for follow-up after 15 days and their improvement in symptoms was noted as complete improvement, some improvement or no improvement on a five point scale. Results: 63.9% cases showed complete improvement, while 36.1% showed some improvement. None of the patients was without any improvement. Vaginal discharge syndrome was most common between 20 and 30 years (43.4%), and 67.8% of symptomatic females with vaginal discharge syndrome belonged to the lower socioeconomic group. HSV infection was the most common (15%) associated viral infection with vaginal discharge syndrome, while hepatitis B infection was the least common (0.5%). HIV was reactive in 2.8% cases only. Conclusion: Syndromic management was found to be effective in relieving symptoms in most of the cases of vaginal discharge syndrome

  12. Evaluation of the Ott Hydromet Qliner for measuring discharge in laboratory and field conditions

    USGS Publications Warehouse

    McVay, Jason C.

    2015-01-01

    The U.S. Geological Survey, in collaboration with the University of Iowa IIHR – Hydroscience and Engineering, evaluated the use of the Ott Hydromet Qliner using laboratory flume tests along with field validation tests. Analysis of the flume testing indicates the velocities measured by the Qliner at a 40-second exposure time results in higher dispersion of velocities from the mean velocity of data collected with a 5-minute exposure time. The percent data spread from the mean of a 100-minute mean of Qliner velocities for a 40-second exposure time averaged 16.6 percent for the entire vertical, and a 5-minute mean produced a 6.2 percent data spread from the 100-minute mean. This 16.6 percent variation in measured velocity would result in a 3.32 percent variation in computed discharge assuming 25 verticals while averaging 4 bins in each vertical. The flume testing also provided results that indicate the blanking distance of 0.20 meters is acceptable when using beams 1 and 2, however beam 3 is negatively biased near the transducer and the 0.20-meter blanking distance is not sufficient. Field testing included comparing the measured discharge by the Qliner to the discharge measured by a Price AA mechanical current meter and a Teledyne RDI Rio Grande 1200 kilohertz acoustic Doppler current profiler. The field tests indicated a difference between the discharges measured with the Qliner and the field reference discharge between -14.0 and 8.0 percent; however the average percent difference for all 22 field comparisons was 0.22, which was not statistically significant.

  13. A New Image Based Approach to Measure Discharge and Soil Saturation

    NASA Astrophysics Data System (ADS)

    Kaplan, Nils; Weiler, Markus; Blume, Theresa

    2016-04-01

    Discharge measurements are crucial for most hydrological studies. It is common to monitor discharge by recording water level and calculate the actual discharge using a rating curve that has been previously determined for varying flow conditions. Bubble and float gauges as well as radar based gauges are frequently used to measure water level. Recently particle image velocimetry (PIV) approaches have become more attractive due to continuous improvement of sensors and computing power. Standard cameras can be easily usable and cheap monitoring devices for discharge measurement. The combination of a camera and a staff gauge has been proved to be suitable for hydrological monitoring in several studies and is promoted as redundant backup as well as independent system. Our new image based system offers the possibility to measure water velocity and soil saturation in addition to water level. We use a commercial wildlife camera with sensors in the visible and infrared spectrum, allowing for day and night images. The system can be used for three purposes. (1) Water level measurement with a specifically built gauging plate. (2) A carbon fiber stick installed instream allows water velocity measurements. Water velocity can be derived from the bending of the carbon fiber under water pressure which is proportional to the water velocity and water level. Hence we can derive a rating curve between bending angle of the carbon fiber stick and the water velocity. Therefore we can constantly measure the water velocity and do not depend on traditional rating curves. (3) Soil water saturation is measured by perforated PVC bottles that enable water in- and outflow. Rising water level in the PVC-bottle will lift an integrated floating body that pushes up a detection marker visible for the camera above the ground. The measurement system is tested for monitoring intermittent streams in the Attert basin in Luxemburg linking the dynamics of the stream network extent to the surface connectivity

  14. A joined multi-metric calibration of river discharge and nitrate loads with different performance measures

    NASA Astrophysics Data System (ADS)

    Haas, Marcelo B.; Guse, Björn; Pfannerstill, Matthias; Fohrer, Nicola

    2016-05-01

    Hydrological models are useful tools to investigate hydrology and water quality in catchments. The calibration of these models is a crucial step to adapt the model to the catchment conditions, allowing effective simulations of environmental processes. In the model calibration, different performance measures need to be considered to represent different hydrology and water quality conditions in combination. This study presents a joined multi-metric calibration of discharge and nitrate loads simulated with the ecohydrological model SWAT. For this purpose, a calibration approach based on flow duration curves (FDC) is advanced by also considering nitrate duration curves (NDC). Five segments of FDCs and of NDCs are evaluated separately to consider the different phases of hydrograph and nitrograph. To consider both magnitude and dynamics in river discharge and nitrate loads, the Kling-Gupta Efficiency (KGE) is used additionally as a statistical performance metric to achieve a joined multi-variable calibration. The results show that a separate assessment of five different magnitudes improves the calibrated nitrate loads. Subsequently, adequate model runs with good performance for different hydrological conditions both for discharge and nitrate are detected in a joined approach based on FDC, NDC, and KGE. In that manner, plausible results were obtained for discharge and nitrate loads in the same model run. Using a multi-metric performance approach, the simultaneous multi-variable calibration led to a balanced model result for all magnitudes of discharge and nitrate loads.

  15. Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

    SciTech Connect

    Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Chuaqui, H.; Kakati, M.

    2011-10-15

    Self-excited plasma series resonance is observed in low pressure capacitvely coupled radio frequency discharges as high-frequency oscillations superimposed on the normal radio frequency current. This high-frequency contribution to the radio frequency current is generated by a series resonance between the capacitive sheath and the inductive and resistive bulk plasma. In this report, we present an experimental method to measure the plasma series resonance in a capacitively coupled radio frequency argon plasma by modifying the homogeneous discharge model. The homogeneous discharge model is modified by introducing a correction factor to the plasma resistance. Plasma parameters are also calculated by considering the plasma series resonances effect. Experimental measurements show that the self-excitation of the plasma series resonance, which arises in capacitive discharge due to the nonlinear interaction of plasma bulk and sheath, significantly enhances both the Ohmic and stochastic heating. The experimentally measured total dissipation, which is the sum of the Ohmic and stochastic heating, is found to increase significantly with decreasing pressure.

  16. Continuous measurement of suspended-sediment discharge in rivers by use of optical backscatterance sensors

    USGS Publications Warehouse

    Schoellhamer, D.H.; Wright, S.A.

    2003-01-01

    Optical sensors have been used to measure turbidity and suspended-sediment concentration by many marine and estuarine studies, and optical sensors can provide automated, continuous time series of suspended-sediment concentration and discharge in rivers. Three potential problems with using optical sensors are biological fouling, particle-size variability, and particle-reflectivity variability. Despite varying particle size, output from an optical backscatterance sensor in the Sacramento River at Freeport, California, USA, was calibrated successfully to discharge-weighted, cross-sectionally averaged suspended-sediment concentration, which was measured with the equal discharge-, or width-increment, methods and an isokinetic sampler. A correction for sensor drift was applied to the 3-year time series. However, the calibration of an optical backscatterance sensor used in the Colorado River at Cisco, Utah, USA, was affected by particle-size variability. The adjusted time series at Freeport was used to calculate hourly suspended-sediment discharge that compared well with daily values from a sediment station at Freeport. The appropriateness of using optical sensors in rivers should be evaluated on a site-specific basis and measurement objectives, potential particle size effects, and potential fouling should be considered.

  17. Measurements and Interpretive 2D Edge Modeling of Lithiated NSTX Discharges

    NASA Astrophysics Data System (ADS)

    Gray, Travis; Ahn, Joon-Wook; Canik, John; Jaworski, Michael; Maingi, Rajesh; Goldston, Robert; Kaita, Robert; Ono, Masa; Scotti, Filippo; McLean, Adam; Soukhanovskii, Vsevolod

    2013-10-01

    The National Spherical Torus Experiment (NSTX) has made extensive use of evaporative lithium coatings for improved discharge performance such as reduced divertor recycling, increased plasma stored energy and duration, and the elimination of Edge Localized Modes (ELMs). Measurements of divertor heat flux are accomplished with a unique dual-band IR (DBIR) thermography system to mitigate the effects of changing surface emissivity. Measurements from the DBIR system show reduced divertor surface temperature at the outer strike point for the case with 300 mg of lithium deposition. This results in the divertor heat flux being reduced from 5 to 2.5 MW/m2. In turn, a reduction in divertor power accounting at the outer strike point is measured with increased lithium evaporation such that PdivIR /Ploss ~ 0.3 - 0.5 for discharges with 150 mg of lithium and 0.12 - 0.2 for discharges with 300 mg of lithium. The reduction in divertor power is correlated with an increase in divertor radiation for discharges with 300 mg of lithium evaporation. This work was supported by DoE Contracts: DE-AC05-00OR22725, DE-AC52-07NA27344 and DE-AC02-09CH11466.

  18. Dynamics of dielectric barrier discharge in non-uniform gas composition investigated by laser spectroscopic measurements

    NASA Astrophysics Data System (ADS)

    Urabe, Keiichiro; Ito, Yosuke; Choi, Joon-Young; Sakai, Osamu; Tachibana, Kunihide

    2009-10-01

    It is well known that stable and glow dielectric barrier discharge (DBD) at atmospheric pressure is observed using helium gas and AC high voltage of kHz-order frequency. We have investigated the discharge mechanisms of DBDs from a view point of the spatiotemporal distributions of excited species measured by laser spectroscopic methods. In this presentation, we will show convincing arguments about the discharge model of the DBD especially having the non-uniformity of gas composition. As a DBD plasma source for atmospheric pressure processes, we have investigated an atmospheric pressure plasma jet (APPJ) using helium gas flow in ambient air, and this plasma source can be regarded as the DBD near the boundary interface of helium gas and ambient air. In this APPJ, we observed spatiotemporal distributions of excited species density inside the helium gas channel, using laser absorption spectroscopy and laser induced fluorescence, to measure the densities of helium metastable atom (2^3S1 state) and nitrogen ion (X^2σg^+ state) respectively. To study the influence of nitrogen gas contamination on the discharge profile of DBD, we have also applied CO2-laser heterodyne interferometry to measure the special distribution of electron density in parallel-plate DBD.

  19. Discharge rate measurements for Micromegas detectors in the presence of a longitudinal magnetic field

    SciTech Connect

    B. Moreno, S. Aune, J. Ball, G. Charles, A. Giganon, P. Konczykowski, C. Lahonde-Hamdoun, H. Moutarde, S. Procureur, F. Sabatie

    2011-10-01

    We present first discharge rate measurements for Micromegas detectors in the presence of a high longitudinal magnetic field in the GeV kinematical region. Measurements were performed by using two Micromegas detectors and a photon beam impinging a CH{sub 2} target in the Hall B of the Jefferson Laboratory. One detector was equipped with an additional GEM foil, and a reduction of the discharge probability by two orders of magnitude compared to the stand-alone Micromegas was observed. The detectors were p laced in the FROST solenoid providing a longitudinal magnetic field up to 5T. It allowed for precise measurements of the discharge probability dependence with a diffusion-reducing magnetic field. Between 0 and 5T, the discharge probability increased by a factor of 10 for polar angles between 19{degrees} and 34{degrees}. A GEANT4-based simulation developed for sparking rate calculation was calibrated against these data in order to predict the sparking rate in a high longitudinal magnetic field environment. This simulati on is then used to investigate the possible use of Micromegas in the Forward Vertex Tracker (FVT) of the future CLAS12 spectrometer. In the case of the FVT a sparking rate of 1Hz per detector was obtained at the anticipated CLAS12 luminosity.

  20. Discharge and other hydraulic measurements for characterizing the hydraulics of Lower Congo River

    USGS Publications Warehouse

    Oberg, Kevin; Shelton, John M.; Gardiner, Ned; Jackson, P. Ryan

    2009-01-01

    The first direct measurements of discharge of the Lower Congo River below Malebo Pool and upstream from Kinganga, Democratic Republic of Congo (DRC) were made in July 2008 using acoustic Doppler current profilers, differential GPS, and echo sounders. These measurements were made in support of research that is attempting to understand the distribution of fish species in the Lower Congo River and reasons for separation of species within this large river. Analyses of these measurements show that the maximum depth in the Lower Congo River was in excess of 200 m and maximum water velocities were greater than 4 m/s. The discharge measured near Luozi, DRC was 35,800 m3/s, and decreased slightly beginning midway through the study. Local bedrock controls seem to have a large effect on the flow in the river, even in reaches without waterfalls and rapids. Dramatic changes in bed topography are evident in transects across the river.

  1. Differences in rating curve and hydrograph uncertainty due to streamflow dynamics and number of discharge measurements

    NASA Astrophysics Data System (ADS)

    Rosenstand Poulsen, Jane; Bering Ovesen, Niels; Larsen, Søren Erik; Tornbjerg, Henrik

    2015-04-01

    The uncertainty related to the use of rating curves for hydrograph estimation is strongly affected if changes in cross-sectional geometry or friction properties occur, especially if the changes are abrupt. In lowland moderately sized streams in temperate regions, such flow changes are often associated with seasonal weed growth. The gradual increase in channel bed roughness caused by weed growth is commonly accounted for by a likewise gradual shift of the rating curve according to monthly discharge measurements. However, this measurement approach is sensitive to abrupt changes in flow, which occur for instance in dynamic streams exhibiting a large difference between maximum and minimum flow or during high summer flows or winter flooding. Hence, the purpose of this study is to investigate the role that dynamic versus stable streams play in terms of uncertainty of establishing rating curves and calculating hydrographs with the traditional stage-discharge approach. Such an analysis is highly valuable in terms of addressing the possibility of adapting hydrograph estimation procedures to the specific streamflow dynamics, thereby quantifying and potentially lowering the uncertainty of hydrograph estimates. Based on results from the Danish national rainfall-runoff model, ratios between yearly median maximum and median minimum stream discharge were calculated for 15 km2 sub-catchments for the entire country. Based on these values, ten gauging stations were selected, located to cover the range of flow regimes represented by the calculated max/min discharge ratios. The selected gauging stations were all stations that had at least three consecutive years with historical data series where direct stream discharge had been measured twenty or more times each year. Based on these data series, new sub-series were created by continuously thinning out the number of discharge measurements. Then, for each of these constructed data series a rating curve and a hydrograph were established

  2. Complete velocity distribution in river cross-sections measured by acoustic instruments

    USGS Publications Warehouse

    Cheng, R.T.; Gartner, J.W.

    2003-01-01

    To fully understand the hydraulic properties of natural rivers, velocity distribution in the river cross-section should be studied in detail. The measurement task is not straightforward because there is not an instrument that can measure the velocity distribution covering the entire cross-section. Particularly, the velocities in regions near the free surface and in the bottom boundary layer are difficult to measure, and yet the velocity properties in these regions play the most significant role in characterizing the hydraulic properties. To further characterize river hydraulics, two acoustic instruments, namely, an acoustic Doppler current profiler (ADCP), and a "BoogieDopp" (BD) were used on fixed platforms to measure the detailed velocity profiles across the river. Typically, 20 to 25 stations were used to represent a river cross-section. At each station, water velocity profiles were measured independently and/or concurrently by an ADCP and a BD. The measured velocity properties were compared and used in computation of river discharge. In a tow-tank evaluation of a BD, it has been confirmed that BD is capable of measuring water velocity at about 11 cm below the free-surface. Therefore, the surface velocity distribution across the river was extracted from the BD velocity measurements and used to compute the river discharge. These detailed velocity profiles and the composite velocity distribution were used to assess the validity of the classic theories of velocity distributions, conventional river discharge measurement methods, and for estimates of channel bottom roughness.

  3. Measuring the Discharge of River Flood Using Witnesses Movies Found on the Internet

    NASA Astrophysics Data System (ADS)

    Hauet, A.; Le Coz, J.; Le Boursicaud, R.; Pénard, L.

    2014-12-01

    The knowledge of the discharge of river during extreme flood is of prime importance for the scientific and the research community. Unfortunately, measuring discharge using conventional methods is impossible because the high velocities and the floating debris endanger the operators and the equipment. The typical time-scale for gauging does not match up to the time scale of the dynamic of extreme flood. Finally, floods are mesoscale events that affect generally several watersheds at the same time, and gauging teams do not have the capabilities for covering the whole region of interest. Recently, non intrusive method for measuring discharge have been developed and tested in flood conditions. Doppler surface velocity radar and Large Scale Particle Image Velocimetry (LSPIV) showed their efficiency for measuring discharge during extreme events, but those methods need to be deployed by operators and the problems of time-scale and space-scale covering aforementioned are not solved. In this study, authors present how flood discharge measurement can benefits from the huge development, the last 10 years, of internet and of the on-line sharing of files. Floods are impressive phenomena, and hundreds of witnesses movies can be found on the internet after every important event. The different steps in order to apply LSPIV analysis to witness movie are detailed: (i) selection of the video of interest; (ii) contact with the author of the video; (iii) preparing the video for the LSPIV analysis : stabilization of the images, field campaigns; (iv) LSPIV analysis, providing surface velocity field; and (v)discharge computation. A case study on the major flash flood of 18 June 2013 of the Gave River at Cauterets, French Pyrennees, is presented. Results show that witnesses movies can bring useful information and allow estimating discharges values. Capabilities and limitations of LSPIV applied to witnesses movies are detailed. Finally, the paper presents an approach conducted within the

  4. Fluvial sediments a summary of source, transportation, deposition, and measurement of sediment discharge

    USGS Publications Warehouse

    Colby, B.R.

    1963-01-01

    continuously at about the velocity of the flow, and even low flows can transport large amounts of fine sediment. Hence, the discharge of fine sediments, being largely dependent on the availability of fine sediment upstream rather than on the properties of the sediment and of the flow at a cross section, can seldom be computed from properties, other than concentrations based directly on samples, that can be observed at the cross section. Sediment particles continually change their positions in the flow; some fall to the streambed, and others are removed from the bed. Sediment deposits form locally or over large areas if the volume rate at which particles settle to the bed exceeds the volume rate at which particles are removed from the bed. In general, large particles are deposited more readily than small particles, whether the point of deposition is behind a rock, on a flood plain, within a stream channel, or at the entrance to a reservoir, a lake, or the ocean. Most samplers used for sediment observations collect a water-sediment mixture from the water surface to within a few tenths of a foot of the streambed. They thus sample most of the suspended sediment, especially if the flow is deep or if the sediment is mostly fine; but they exclude the bedload and some of the suspended sediment in a layer near the streambed where the suspended-sediment concentrations are highest. Measured sediment discharges are usually based on concentrations that are averages of several individual sediment samples for a cross section. If enough average concentrations for a cross section have been determined, the measured sediment discharge can be computed by interpolating sediment concentrations between sampling times. If only occasional samples were collected, an average relation between sediment discharge and flow can be used with a flow-duration curve to compute roughly the average or the total sediment discharges for any periods of time for which the flow-duration c

  5. Benchmarking laboratory observation uncertainty for in-pipe storm sewer discharge measurements

    NASA Astrophysics Data System (ADS)

    Aguilar, Marcus F.; McDonald, Walter M.; Dymond, Randel L.

    2016-03-01

    The uncertainty associated with discharge measurement in storm sewer systems is of fundamental importance for hydrologic/hydraulic model calibration and pollutant load estimation, although it is difficult to determine as field benchmarks are generally impractical. This study benchmarks discharge uncertainty in several commonly used sensors by laboratory flume testing with and without a woody debris model. The sensors are then installed in a field location where laboratory benchmarked uncertainty is applied to field measurements. Combined depth and velocity uncertainty from the laboratory ranged from ±0.207-0.710 in., and ±0.176-0.631 fps respectively, and when propagated and applied to discharge estimation in the field, resulted in field discharge uncertainties of between 13% and 256% of the observation. Average daily volume calculation based on these observations had uncertainties of between 58% and 99% of the estimated value, and the uncertainty bounds of storm flow volume and peak flow for nine storm events constituted between 31-84%, and 13-48% of the estimated value respectively. Subsequently, the implications of these observational uncertainties for stormwater best-management practice evaluation, hydrologic modeling, and Total Maximum Daily Load development are considered.

  6. Measurement and simulation of partial discharge in oil impregnated pressboard with an electrical aging process

    NASA Astrophysics Data System (ADS)

    Li, Junhao; Si, Wenrong; Yao, Xiu; Li, Yanming

    2009-10-01

    The continuous test on oil impregnated pressboard insulation with internal void defect was developed and the phase resolved partial discharge (PRPD) pattern of partial discharge (PD) signals during the electrical aging process was measured. Two different void structures which have different void volume were used in this experiment. It shows that the PD pattern could be classified into five stages and a great diversity in the first four stages is observed. The larger void volume leads to larger PD magnitude. The computer numerical simulation model which is based on a physical discharge process was used and the causes of PD pattern change were interpreted by comparison with computer numerical simulation results. The initial values and change tendency of gas pressure and surface conductivity were determined through experiment. The model parameters in different stages have been studied as well as the insight into the physical changes in the void during electrical aging. The results provide rules for the identification of the electrical aging stage through the partial discharge measurements.

  7. Compact high-speed reciprocating probe system for measurements in a Hall thruster discharge and plume.

    PubMed

    Dannenmayer, K; Mazouffre, S

    2012-12-01

    A compact high-speed reciprocating probe system has been developed in order to perform measurements of the plasma parameters by means of electrostatic probes in the discharge and the plume of a Hall thruster. The system is based on a piezoelectric linear drive that can achieve a speed of up to 350 mm/s over a travel range of 90 mm. Due to the high velocity of the linear drive the probe can be rapidly moved in and out the measurement region in order to minimize perturbation of the thruster discharge due to sputtering of probe material. To demonstrate the impact of the new system, a heated emissive probe, installed on the high-speed translation stage, was used to measure the plasma potential and the electron temperature in the near-field plume of a low power Hall thruster. PMID:23277983

  8. Compact high-speed reciprocating probe system for measurements in a Hall thruster discharge and plume

    SciTech Connect

    Dannenmayer, K.; Mazouffre, S.

    2012-12-15

    A compact high-speed reciprocating probe system has been developed in order to perform measurements of the plasma parameters by means of electrostatic probes in the discharge and the plume of a Hall thruster. The system is based on a piezoelectric linear drive that can achieve a speed of up to 350 mm/s over a travel range of 90 mm. Due to the high velocity of the linear drive the probe can be rapidly moved in and out the measurement region in order to minimize perturbation of the thruster discharge due to sputtering of probe material. To demonstrate the impact of the new system, a heated emissive probe, installed on the high-speed translation stage, was used to measure the plasma potential and the electron temperature in the near-field plume of a low power Hall thruster.

  9. Measurement of the electron density in a subatmospheric dielectric barrier discharge by spectral line shape

    SciTech Connect

    Dong Lifang; Qi Yuyan; Liu Weiyuan; Fan Weili

    2009-07-01

    The electron density in a subatmospheric dielectric barrier discharge by using argon spectral line shape is measured for the first time. With the gas pressure increasing in the range of 1x10{sup 4} Pa-6x10{sup 4} Pa, the line profiles of argon 696.54 nm are measured. An asymmetrical deconvolution procedure is applied to separate the Gaussian and Lorentzian profile from the measured spectral line. The gas temperature is estimated by using rotational temperature of N{sub 2}{sup +}. By subtracting the van der Waals broadening and partial Lorentzian instrumental broadening from the Lorentzian broadening, the Stark broadening is obtained and used to estimate the electron density. It is found that the electron density in dielectric barrier discharge increases with the increase in gas pressure.

  10. A synchronized emissive probe for time-resolved plasma potential measurements of pulsed discharges

    SciTech Connect

    Sanders, Jason M.; Rauch, Albert; Mendelsberg, Rueben J.; Anders, Andre

    2011-09-15

    A pulsed emissive probe technique is presented for measuring the plasma potential of pulsed plasma discharges. The technique provides time-resolved data and features minimal disturbance of the plasma achieved by alternating probe heating with the generation of plasma. Time resolution of about 20 ns is demonstrated for high power impulse magnetron sputtering (HIPIMS) plasma of niobium in argon. Spatial resolution of about 1 mm is achieved by using a miniature tungsten filament mounted on a precision translational stage. Repeated measurements for the same discharge conditions show that the standard deviation of the measurements is about 1-2 V, corresponding to 4%-8% of the maximum plasma potential relative to ground. The principle is demonstrated for measurements at a distance of 30 mm from the target, for different radial positions, at an argon pressure of 0.3 Pa, a cathode voltage of -420 V, and a discharge current of about 60 A in the steady-state phase of the HIPIMS pulse.

  11. Plume and Discharge Plasma Measurements of an NSTAR-type Ion Thruster

    NASA Technical Reports Server (NTRS)

    Foster, John E; Soulas, George C.; Patterson, Michael J.

    2000-01-01

    The success of the NASA Deep Space I spacecraft has demonstrated that ion propulsion is a viable option for deep space science missions. More aggressive missions such as Comet Nuclear Sample Return and Europa lander will require higher power, higher propellant throughput and longer thruster lifetime than the NASA Solar Electric Propulsion Technology Application Readiness (NSTAR) engine. Presented here are thruster plume and discharge plasma measurements of an NSTAR-type thruster operated from 0.5 kW to 5 kW. From Faraday plume sweeps, beam divergence was determined. From Langmuir probe plume measurements on centerline, low energy ion production on axis due to charge-exchange and direct ionization was assessed. Additionally, plume plasma potential measurements made on axis were used to determine the upper energy limits at which ions created on centerline could be radially accelerated. Wall probes flush-mounted to the thruster discharge chamber anode were used to assess plasma conditions. Langmuir probe measurements at the wall indicated significant differences in the electron temperature in the cylindrical and conical sections of the discharge chamber.

  12. Electron density measurement in gas discharge plasmas by optical and acoustic methods

    NASA Astrophysics Data System (ADS)

    Biagioni, A.; Anania, M. P.; Bellaveglia, M.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Filippi, F.; Mostacci, A.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

    2016-08-01

    Plasma density represents a very important parameter for both laser wakefield and plasma wakefield acceleration, which use a gas-filled capillary plasma source. Several techniques can be used to measure the plasma density within a capillary discharge, which are mainly based on optical diagnostic methods, as for example the well-known spectroscopic method using the Stark broadening effect. In this work, we introduce a preliminary study on an alternative way to detect the plasma density, based on the shock waves produced by gas discharge in a capillary. Firstly, the measurements of the acoustic spectral content relative to the laser-induced plasmas by a solid target allowed us to understand the main properties of the acoustic waves produced during this kind of plasma generation; afterwards, we have extended such acoustic technique to the capillary plasma source in order to calibrate it by comparison with the stark broadening method.

  13. Direct measurement of the matched spot size in a slow capillary discharge optical waveguide.

    PubMed

    Antsiferov, Pavel S; Akdim, Mohamed R; van Dam, Herman T

    2007-12-01

    This communication presents direct method for experimental determining the matched spot size in a plasma optical waveguide, created in a slow capillary discharge. It can be used for Laser Wakefield Acceleration experiments in addition to interferometry for fast control of optical properties of discharge plasma. The measurements are done by means of the comparison of the laser beam size at the entrance and at the exit of the plasma channel. They are direct in the sense that the interpretation is made in terms of the refractive index without usage of the information about electron density distribution. The method can be used for matched spot size measurement in conditions of the nonlinear effects (transmission of high power laser pulses). PMID:18163720

  14. Development of far infrared attenuation to measure electron densities in cw pin discharge lasers

    NASA Technical Reports Server (NTRS)

    Babcock, R. V.

    1977-01-01

    A two beam attenuation technique was devised to measure electron densities 10 to the 9th power to 10 to the 11th power cm/3 resolved to 1 cm, in a near atmospheric COFFEE laser discharge, using 496 micrometer and 1,220 micrometer radiations from CH3F, optically pumped by a CO2 laser. A far infrared generator was developed which was suitable except for a periodic intensity variation in FIR output deriving from frequency variation of the pump radiation.

  15. Electron density measurements in a pulse-repetitive microwave discharge in air

    SciTech Connect

    Nikolic, M.; Popovic, S.; Vuskovic, L.; Herring, G. C.; Exton, R. J.

    2011-12-01

    We have developed a technique for absolute measurements of electron density in pulse-repetitive microwave discharges in air. The technique is based on the time-resolved absolute intensity of a nitrogen spectral band belonging to the Second Positive System, the kinetic model and the detailed particle balance of the N{sub 2}C{sup 3}{Pi}{sub u} ({nu} = 0) state. This new approach bridges the gap between two existing electron density measurement methods (Langmuir probe and Stark broadening). The electron density is obtained from the time-dependent rate equation for the population of N{sub 2}C{sup 3}{Pi}{sub u} ({nu} = 0) using recorded waveforms of the absolute C{sup 3}{Pi}{sub u}{yields}B{sup 3}{Pi}{sub g} (0-0) band intensity, the forward and reflected microwave power density. Measured electron density waveforms using numerical and approximated analytical methods are presented for the case of pulse repetitive planar surface microwave discharge at the aperture of a horn antenna covered with alumina ceramic plate. The discharge was generated in air at 11.8 Torr with a X-band microwave generator using 3.5 {mu}s microwave pulses at peak power of 210 kW. In this case, we were able to time resolve the electron density within a single 3.5 {mu}s pulse. We obtained (9.0 {+-} 0.6) x 10{sup 13} cm{sup -3} for the peak and (5.0 {+-} 0.6) x 10{sup 13} cm{sup -3} for the pulse-average electron density. The technique presents a convenient, non-intrusive diagnostic method for local, time-defined measurements of electron density in short duration discharges near atmospheric pressures.

  16. CXRS measurements of ion temperature in NBI discharges on Globus-M spherical tokamak

    NASA Astrophysics Data System (ADS)

    Avdeeva, G. F.; Miroshnikov, I. V.; Bakharev, N. N.; Kurskiev, G. S.; Patrov, M. I.; Sergeev, V. Yu; Schegolev, P. B.

    2016-01-01

    The thesis describes the Charge-eXchange Recombination Spectroscopy (CXRS) diagnostics setup and its application to the ion temperature determination in the NBI-heated discharges in the Globus-M spherical tokamak. Measurements of the spectral line shape of the radiation emitted by the hydrogen-like carbon ion CVI (5290.5 Å) are presented. Comparison of CXRS and Neutral Particle Analyser (NPA) data demonstrates good agreement.

  17. Evaluation of the depth-integration method of measuring water discharge in large rivers

    NASA Astrophysics Data System (ADS)

    Moody, John A.; Troutman, Brent M.

    1992-07-01

    The depth-integration method oor measuring water discharge makes a continuos measurement of the water velocity from the water surface to the bottom at 20 to 40 locations or verticals across a river. It is especially practical for large rivers where river traffic makes it impractical to use boats attached to taglines strung across the river or to use current meters suspended from bridges. This method has the additional advantage over the standard two- and eight-tenths method in that a discharge-weighted suspended-sediment sample can be collected at the same time. When this method is used in large rivers such as the Missouri, Mississippi and Ohio, a microwave navigation system is used to determine the ship's position at each vertical sampling location across the river, and to make accurate velocity corrections to compensate for shift drift. An essential feature is a hydraulic winch that can lower and raise the current meter at a constant transit velocity so that the velocities at all depths are measured for equal lengths of time. Field calibration measurements show that: (1) the mean velocity measured on the upcast (bottom to surface) is within 1% of the standard mean velocity determined by 9-11 point measurements; (2) if the transit velocity is less than 25% of the mean velocity, then average error in the mean velocity is 4% or less. The major source of bias error is a result of mounting the current meter above a sounding weight and sometimes above a suspended-sediment sampling bottle, which prevents measurement of the velocity all the way to the bottom. The measured mean velocity is slightly larger than the true mean velocity. This bias error in the discharge is largest in shallow water (approximately 8% for the Missouri River at Hermann, MO, where the mean depth was 4.3 m) and smallest in deeper water (approximately 3% for the Mississippi River at Vickbsurg, MS, where the mean depth was 14.5 m). The major source of random error in the discharge is the natural

  18. Evaluation of the depth-integration method of measuring water discharge in large rivers

    USGS Publications Warehouse

    Moody, J.A.; Troutman, B.M.

    1992-01-01

    The depth-integration method oor measuring water discharge makes a continuos measurement of the water velocity from the water surface to the bottom at 20 to 40 locations or verticals across a river. It is especially practical for large rivers where river traffic makes it impractical to use boats attached to taglines strung across the river or to use current meters suspended from bridges. This method has the additional advantage over the standard two- and eight-tenths method in that a discharge-weighted suspended-sediment sample can be collected at the same time. When this method is used in large rivers such as the Missouri, Mississippi and Ohio, a microwave navigation system is used to determine the ship's position at each vertical sampling location across the river, and to make accurate velocity corrections to compensate for shift drift. An essential feature is a hydraulic winch that can lower and raise the current meter at a constant transit velocity so that the velocities at all depths are measured for equal lengths of time. Field calibration measurements show that: (1) the mean velocity measured on the upcast (bottom to surface) is within 1% of the standard mean velocity determined by 9-11 point measurements; (2) if the transit velocity is less than 25% of the mean velocity, then average error in the mean velocity is 4% or less. The major source of bias error is a result of mounting the current meter above a sounding weight and sometimes above a suspended-sediment sampling bottle, which prevents measurement of the velocity all the way to the bottom. The measured mean velocity is slightly larger than the true mean velocity. This bias error in the discharge is largest in shallow water (approximately 8% for the Missouri River at Hermann, MO, where the mean depth was 4.3 m) and smallest in deeper water (approximately 3% for the Mississippi River at Vickbsurg, MS, where the mean depth was 14.5 m). The major source of random error in the discharge is the natural

  19. Measurements and Simulations of Surface Dielectric Barrier Discharges Used as Plasma Actuators

    NASA Technical Reports Server (NTRS)

    Hoskinson, Alan R.

    2012-01-01

    This report is a Ph.D. dissertation performed under NRA cooperative agreement and submitted as part of the final report. Asymmetric surface dielectric barrier discharges (DBDs) have shown promise for use as aerodynamic actuators for active flow control. In this project we studied DBD actuators experimentally and numerically. Our DBDs used a symmetric triangular high voltage waveform to generate plasma in atmospheric pressure air. Time-averaged measurements indicated that the induced force of a single barrier actuator design (one electrode insulated from the plasma) can be increased exponentially above the results of previous studies by decreasing both the length and thickness of the electrode exposed to the plasma. This increased force may allow these devices to control flow separation in a wider range of flow environments. Experiments using an intensified digital camera to examine the plasma on time scales of a few nanoseconds showed that, in addition to the previously-observed filamentary and jet-like plasma structures, discharges with very thin exposed electrodes exhibited a weak but constant plasma immediately adjacent to those electrodes. In double-barrier actuators (both electrodes insulated), decreasing the diameter of the narrower electrode lead to increasing forces, and recorded images showed the simultaneous existence of both filamentary and jet-like plasma structures. The development and application of a time-dependent, two-dimensional computational fluid plasma model has aided in understanding the detailed physics of surface DBDs at all-time scales. For simulated single-barrier discharges, the model qualitatively reproduced the filamentary and jet-like micro-discharge structures. The model was somewhat successful in reproducing the observed characteristics of double-barrier actuators. For both actuator geometries, the model indicated that the majority of the forces induced on the neutral gas occur in between micro-discharges as the plasmas decay.

  20. Time-resolved temperature and O atom measurements in nanosecond pulse discharges in combustible mixtures

    NASA Astrophysics Data System (ADS)

    Lanier, Suzanne; Bowman, Sherrie; Burnette, David; Adamovich, Igor V.; Lempert, Walter R.

    2014-11-01

    The paper presents results of time-resolved rotational temperature measurements, by pure rotational coherent anti-Stokes Raman spectroscopy and absolute O atom number density measurements, by two-photon absorption laser induced fluorescence. The experiments were conducted in nanosecond pulse discharges in H2-O2-Ar and C2H4-O2-Ar mixtures, initially at room temperature, operated at a high pulse repetition rate of 40 kHz, in a plane-to-plane double dielectric barrier geometry at a pressure of 40 Torr. Intensified charge-coupled device images show that O2-Ar and H2-O2-Ar plasmas remain diffuse and volume-filling during the entire burst. Images taken in C2H4-O2-Ar plasma demonstrate significant discharge filamentation and constriction along the center plane and in the corners of the test section. The experimental results demonstrate high accuracy of pure rotational psec CARS for thermometry measurements at low partial pressures of oxygen in nonequilibrium plasmas. The results are compared with kinetic modeling calculations, using two different H2-O2 chemistry and C2H4-O2 chemistry mechanisms. In H2-O2-Ar mixtures, the kinetic modeling predictions are in fairly good agreement with the data, predicting temperature rise and O atom accumulation in long discharge bursts, up to 450 pulses. The results show that adding hydrogen to the mixture results in an additional temperature rise, due to its partial oxidation by radicals generated in the plasma, essentially without chain branching. In C2H4-O2-Ar mixtures, the model consistently underpredicts both temperature and O atom number density. The most likely reason for the difference between the experimental data and model predictions is discharge filamentation developing when ethylene is added to the O2-Ar mixture, at fairly low temperatures.

  1. Measurement of anode surface temperature in carbon nanomaterial production by arc discharge method

    SciTech Connect

    Liang, Feng; Tanaka, Manabu; Choi, Sooseok; Watanabe, Takayuki

    2014-12-15

    Highlights: • We measured the temperature of anode surface by two-color pyrometry combined with a high speed camera successfully. • Growth temperature of pyrolytic graphite, MWNTs, and nano-graphite particles were in ranges of 2400–2600 K, 2600–2700 K, and 2700–3500 K, respectively. • High temperature contributes to form thermodynamically unstable material. - Abstract: Nano-graphite particles, multi-wall carbon nanotube (MWNT), and pyrolytic graphite were prepared at different positions of the anode surface in an arc discharge. Graphite electrodes were employed for the arc discharge under helium environment at atmospheric pressure. Nano-sized carbon products were characterized by scanning electron microscopy and transmission electron microscopy. During the arc discharge, two-color pyrometry combined with a high-speed camera was conducted to measure the temperature distribution of the anode surface. The growth temperature of pyrolytic graphite, MWNT, and nano-graphite particles were in the ranges of 2400–2600 K, 2600–2700 K, and 2700–3500 K, respectively. The local temperature of anode surface is a critical parameter to determine the products with different morphologies. The formation mechanism of these carbon nanomaterials is suggested based on the local temperature of anode surface and their thermodynamic stability.

  2. Measurement of proton transfer reaction rates in a microwave cavity discharge flowing afterglow

    NASA Astrophysics Data System (ADS)

    Brooke, George M., IV

    The reaction rate coefficients between the hydronium ion and the molecules ethene (C2H4), propene (C 3H6), 1-butene (C4H8) and hydrogen sulfide (H2S) were measured at 296 K. The measured reaction rates were compared to collision rates calculated using average dipole orientation (ADO) theory. Reaction efficiency depends primarily upon the proton affinity of the molecules. All the measurements were obtained using the newly developed microwave cavity discharge flowing afterglow (MCD-FA) apparatus. This device uses an Asmussen-type microwave cavity discharge ion source that is spatially separated from the flow tube, eliminating many of the problems inherent with the original FA devices. In addition to measuring reaction rate coefficients, the MCD-FA was shown to be an effective tool for measuring trace compounds in atmospheric air. This method has many advantages over current detection techniques since compounds can be detected in almost real time, large mass ranges can be scanned quickly, and repeated calibration is not required. Preliminary measurements were made of car exhaust and exhaled alveolar air. Car exhaust showed the presence of numerous hydrocarbons, such as butene, benzene and toluene while the exhaled alveolar air showed the presence of various volatile organic compounds such as methanol and acetone.

  3. Measurements of Nitric Oxide in a Plasma Generated by a Variable-Width, Constant Energy Discharge

    NASA Astrophysics Data System (ADS)

    Burnette, David; Adamovich, Igor; Lempert, Walter; Non-equilibrium Thermodynamics Laboratory Team

    2014-10-01

    A diffuse plasma filament within a low pressure sphere gap was generated using a high voltage, solid state switch. For a constant pressure and overvoltage, the peak current and voltage drop were altered by a change in the ballast resistor while a simultaneous adjustment to the variable pulse width was used to maintain a constant pulse energy. The discharge parameters were chosen to result in a quasi-steady state discharge with near constant current and very little change in size and uniformity for each condition studied. The absolute density and temporal evolution of nitric oxide (NO) was measured via laser-induced fluorescence for each condition. The effect of the pulse characteristics and estimated E/N on the formation of NO are discussed.

  4. Oh Laser-Induced Fluorescence Measurements in Nanosecond Pulse Discharge Plasmas

    NASA Astrophysics Data System (ADS)

    Choi, Inchul; Adamovich, Igor V.; Lempert, Walter R.

    2010-06-01

    We present recent results of laser-induced fluorescence measurements of hydroxyl radical density in repetitively pulsed nanosecond plasmas, created using 10-20 nsec duration, high (up to 20 kV) voltage pulsers, capable of operation at repetition rates as high as 40-50 kHz. OH mole fraction as a function of time with respect to discharge creation is determined, with absolute calibration performed using a Hencken flat flame burner. This paper will focus on a series of low temperature, non-equilibrium kinetics measurements in hydrogen and hydrocarbon-air mixtures, with results compared to predictions of a recently developed plasma chemical oxidation model.

  5. Non-Contact Measurement of Stream Discharge from Land and Helicopter

    NASA Astrophysics Data System (ADS)

    Costa, J. E.; Plant, W. J.; Spicer, K. R.; Cheng, R. T.; Haeni, F. P.; Melcher, N.

    2001-12-01

    The U.S. Geological Survey (USGS) is seeking new technologies that could be used to make routine measurements of river discharge by direct measurement of river cross-sectional area, water surface elevation, and water velocity distribution using non-contact methods. If the non-contact approach is proven valid and accurate, it will reduce streamgaging costs, improve accuracy, and reduce hazards associated with traditional streamgaging methods. After evaluating laser, acoustic, particle-imaging, and radar technologies, radar technology for direct measurement of open-channel discharge seems to be the most promising. A proof-of-concept experiment for non-contact open-channel discharge was conducted at the Skagit River, Washington in April 1999. A van-mounted, side-looking microwave (10GHz) backscattering radar collected surface-velocity data across the 183-m wide river. Surface velocities were converted to mean velocities by assuming a normal open-channel velocity profile (surface velocity times 0.85). Channel cross-sectional area was measured using a 100 MHz ground-penetrating radar suspended from a cableway over the river. Results were excellent (within 1-2 percent of directly measured discharge). A new goal was established to measure both velocity and cross-sectional area from a single point on the side of the river. In 2000, two highly experienced contractors, using monostatic and bistatic radar systems of different frequencies, were unsuccessful in obtaining an image of the bed of a river from the riverbank. Lessons learned from those failures have pointed to an approach that is likely to be successful in a future experiment, namely a bankside-mounted highly directional antenna and a tall scan position. If imaging the bed of the river could not be done from the bank, to avoid the requirements of a bridge or cableway, another approach was tried. In 2001 we tested both the pulsed Doppler radar and ground-penetrating radars mounted on a helicopter. Prototype

  6. Comparative Analysis of Thermography Studies and Electrical Measurement of Partial Discharges in Underground Power Cables

    NASA Astrophysics Data System (ADS)

    Gonzalez-Parada, A.; Guzman-Cabrera, R.; Torres-Cisneros, M.; Guzman-Sepulveda, J. R.

    2015-09-01

    The principal cause of damage in underground power cable installations is partial discharge (PD) activity. PD is a localized non-linear phenomenon of electrical breakdown that occurs in the insulating medium sitting between two conducting materials, which are at different potentials. The damage to the insulating material is induced by the AC voltage to which the insulator is subjected during the discharge process, and it can be directly or indirectly measured by the charge displacement across the insulation and the cavity defect. Non-invasive detection techniques that help in identifying the onset of the discharge process are required as PD is a major issue in terms of maintenance and performance of underground power installations. The main locations of failure are the accessories at points of connection such as terminals or splices. In this article, a study of electrical detection of PD and image processing of thermal pictures is presented. The study was carried out by controllably inducing specific failures in the accessories of the installation. The temporal evolution of the PD signals was supported with thermal images taken during the test in order to compare the PD activity and thermal increase due to failure. The analysis of thermographic images allows location of the failure by means of intensity-based texture segmentation algorithms. This novel technique was found to be suitable for non-invasive detection of the PD activity in underground power cable accessories.

  7. Species and temperature measurements of methane oxidation in a nanosecond repetitively pulsed discharge

    PubMed Central

    Lefkowitz, Joseph K; Guo, Peng; Rousso, Aric; Ju, Yiguang

    2015-01-01

    Speciation and temperature measurements of methane oxidation during a nanosecond repetitively pulsed discharge in a low-temperature flow reactor have been performed. Measurements of temperature and formaldehyde during a burst of pulses were made on a time-dependent basis using tunable diode laser absorption spectroscopy, and measurements of all other major stable species were made downstream of a continuously pulsed discharge using gas chromatography. The major species for a stoichiometric methane/oxygen/helium mixture with 75% dilution are H2O, CO, CO2, H2, CH2O, CH3OH, C2H6, C2H4 and C2H2. A modelling tool to simulate homogeneous plasma combustion kinetics is assembled by combining the ZDPlasKin and CHEMKIN codes. In addition, a kinetic model for plasma-assisted combustion (HP-Mech/plasma) of methane, oxygen and helium mixtures has been assembled to simulate the measurements. Predictions can accurately capture reactant consumption as well as production of the major product species. However, significant disagreement is found for minor species, particularly CH2O and CH3OH. Further analysis revealed that the plasma-activated low-temperature oxidation pathways, particularly those involving CH3O2 radical reactions and methane reactions with O(1D), are responsible for this disagreement. PMID:26170433

  8. Measurement and modeling of electric field and space-charge distributions in obstructed helium discharge

    SciTech Connect

    Fendel, Peter; Ganguly, Biswa N.; Bletzinger, Peter

    2015-08-15

    Axial and radial variations of electric field have been measured in dielectric shielded 0.025 m diameter parallel plate electrode with 0.0065 m gap for 1.6 mA, 2260 V helium dc discharge at 1.75 Torr. The axial and radial electric field profiles have been measured from the Stark splitting of 2{sup 1}S→11 {sup 1}P transition through collision induced fluorescence from 4{sup 3}D→2{sup 3}P. The electric field values showed a strong radial variation peaking to 500 kV/m near the cathode radial boundary, and decreasing to about 100 kV/m near the anode edge, suggesting the formation of an obstructed discharge for this low nd condition, where n is the gas density and d is the gap distance. The off-axis Stark spectra showed that the electric field vector deviates from normal to the cathode surface which permits longer path electron trajectories in the inter-electrode gap. Also, the on-axis electric field gradient was very small and off-axis electric field gradient was large indicating a radially non-uniform current density. In order to obtain information about the space charge distribution in this obstructed discharge, it was modeled using the 2-d axisymmetric Poisson solver with the COMSOL finite element modeling program. The best fit to the measured electric field distribution was obtained with a space charge variation of ρ(r) = ρ{sub 0}(r/r{sub 0}){sup 3}, where ρ(r) is the local space charge density, ρ{sub 0} = 6 × 10{sup −3} Coulomb/m{sup 3}, r is the local radial value, and r{sub 0} is the radius of the electrode.

  9. Estimating reach-averaged discharge for the River Severn from measurements of river water surface elevation and slope

    NASA Astrophysics Data System (ADS)

    Durand, Michael; Neal, Jeffrey; Rodríguez, Ernesto; Andreadis, Konstantinos M.; Smith, Laurence C.; Yoon, Yeosang

    2014-04-01

    An algorithm is presented that calculates a best estimate of river bathymetry, roughness coefficient, and discharge based on input measurements of river water surface elevation (h) and slope (S) using the Metropolis algorithm in a Bayesian Markov Chain Monte Carlo scheme, providing an inverse solution to the diffusive approximation to the shallow water equations. This algorithm has potential application to river h and S measurements from the forthcoming Surface Water and Ocean Topography (SWOT) satellite mission. The algorithm was tested using in situ data as a proxy for satellite measurements along a 22.4 km reach of the River Severn, UK. First, the algorithm was run with gage measurements of h and S during a small, in-bank event in June 2007. Second, the algorithm was run with measurements of h and S estimated from four remote sensing images during a major out-of-bank flood event in July 2007. River width was assumed to be known for both events. Algorithm-derived estimates of river bathymetry were validated using in situ measurements, and estimates of roughness coefficient were compared to those used in an operational hydraulic model. Algorithm-derived estimates of river discharge were evaluated using gaged discharge. For the in-bank event, when lateral inflows from smaller tributaries were assumed to be known, the method provided an accurate discharge estimate (10% RMSE). When lateral inflows were assumed unknown, discharge RMSE increased to 36%. Finally, if just one of the three river reaches was assumed to be have known bathymetry, solutions for bathymetry, roughness and discharge for all three reaches were accurately retrieved, with a corresponding discharge RMSE of 15.6%. For the out-of-bank flood event, the lateral inflows were unknown, and the final discharge RMSE was 19%. These results suggest that it should be possible to estimate river discharge via SWOT observations of river water surface elevation, slope and width.

  10. TALIF measurements of oxygen atom density in the afterglow of a capillary nanosecond discharge

    NASA Astrophysics Data System (ADS)

    Klochko, A. V.; Lemainque, J.; Booth, J. P.; Starikovskaia, S. M.

    2015-04-01

    The atomic oxygen density has been measured in the afterglow of a capillary nanosecond discharge in 24-30 mbar synthetic air (N2 : O2 = 4 : 1) by the two-photon absorption laser-induced fluorescence (TALIF) technique, combined with absolute calibration by comparison with xenon TALIF. The discharge was initiated by a train of 30 ns FWHM pulses of alternating positive-negative-positive polarity, separated by 250 ns, with a train repetition frequency of 10 Hz. The amplitude of the first pulse was 10 kV in the cable. A flow of synthetic air through the tube provided complete gas renewal between pulse trains. The O-atom density measurements were made over the time interval 200 ns-2 µs after the initial pulse. The gas temperature was determined by analysis of the molecular nitrogen second positive system optical emission spectrum. The influence of the gas temperature on the atom density measurements, and the reactions producing O atoms, are discussed.

  11. Stage-discharge rating curves based on satellite altimetry and modeled discharge in the Amazon basin

    NASA Astrophysics Data System (ADS)

    Paris, Adrien; Dias de Paiva, Rodrigo; Santos da Silva, Joecila; Medeiros Moreira, Daniel; Calmant, Stephane; Garambois, Pierre-André; Collischonn, Walter; Bonnet, Marie-Paule; Seyler, Frederique

    2016-05-01

    against Acoustic Doppler current profiler (ADCP) cross sections with an accuracy of more than 90%. Altimetry measurements are routinely delivered within a few days, and this RC data set provides a simple and cost-effective tool for predicting discharge throughout the basin in nearly real time.

  12. Discharge Measurements in Shallow Urban Streams Using a Hydroacoustic Current Meter

    USGS Publications Warehouse

    Fisher, G.T.; Morlock, S.E.

    2002-01-01

    Hydroacoustic current-meter measurements were evaluated in small urban streams under a range of stages, velocities, and channel-bottom materials. Because flow in urban streams is often shallow, conventional mechanical current-meter measurements are difficult or impossible to make. The rotating-cup Price pygmy meter that is widely used by the U.S. Geological Survey and other agencies should not be used in depths below 0.20 ft and velocities less than 0.30 ft/s. The hydroacoustic device provides measurements at depths as shallow as 0.10 ft and velocities as low as 0.10 ft/s or less. Measurements using the hydroacoustic current meter were compared to conventional discharge measurements. Comparisons with Price-meter measurements were favorable within the range of flows for which the meters are rated. Based on laboratory and field tests, velocity measurements with the hydroacoustic cannot be validated below about 0.07 ft/s. However, the hydroacoustic meter provides valuable information on direction and magnitude of flow even at lower velocities, which otherwise could not be measured with conventional measurements.

  13. Measurement of plasma parameter in Dielectric Barrier Discharge (DBD) by Moiré deflectometry technique

    NASA Astrophysics Data System (ADS)

    Salimi Meidanshahi, Fatemeh; Madanipour, Khosro; Shokri, Babak; Khani, Mohammad Reza; Borzoki, Hamid Razavi

    2015-05-01

    In this work it is shown that the refractive index and temperature distribution of atmospheric Dielectric Barrier Discharge (DBD) plasmas are measured by Moiré deflectometry. Fringe analysis is used to calculate Moiré deflection and to evaluate refractive index in different points of plasma. By Sa-Ha equation and considering the first ionization, the dependence of refractive index and temperature, electrons, ions and molecules number densities of DBD plasma is obtained. By knowing this relation between plasma parameters, the spatial distributions of the plasma refractive index and temperature are evaluated. The advantages of this method are: simplicity, non-contact, non-destructive measurement, low cost, high accuracy and direct measurement of refractive index gradient.

  14. The Effect of Rainfall Measurement Technique and Its Spatiotemporal Resolution on Discharge Predictions in the Netherlands

    NASA Astrophysics Data System (ADS)

    Uijlenhoet, R.; Brauer, C.; Overeem, A.; Sassi, M.; Rios Gaona, M. F.

    2014-12-01

    Several rainfall measurement techniques are available for hydrological applications, each with its own spatial and temporal resolution. We investigated the effect of these spatiotemporal resolutions on discharge simulations in lowland catchments by forcing a novel rainfall-runoff model (WALRUS) with rainfall data from gauges, radars and microwave links. The hydrological model used for this analysis is the recently developed Wageningen Lowland Runoff Simulator (WALRUS). WALRUS is a rainfall-runoff model accounting for hydrological processes relevant to areas with shallow groundwater (e.g. groundwater-surface water feedback). Here, we used WALRUS for case studies in a freely draining lowland catchment and a polder with controlled water levels. We used rain gauge networks with automatic (hourly resolution but low spatial density) and manual gauges (high spatial density but daily resolution). Operational (real-time) and climatological (gauge-adjusted) C-band radar products and country-wide rainfall maps derived from microwave link data from a cellular telecommunication network were also used. Discharges simulated with these different inputs were compared to observations. We also investigated the effect of spatiotemporal resolution with a high-resolution X-band radar data set for catchments with different sizes. Uncertainty in rainfall forcing is a major source of uncertainty in discharge predictions, both with lumped and with distributed models. For lumped rainfall-runoff models, the main source of input uncertainty is associated with the way in which (effective) catchment-average rainfall is estimated. When catchments are divided into sub-catchments, rainfall spatial variability can become more important, especially during convective rainfall events, leading to spatially varying catchment wetness and spatially varying contribution of quick flow routes. Improving rainfall measurements and their spatiotemporal resolution can improve the performance of rainfall

  15. Dielectric Barrier Discharge (DBD) Plasma Actuators Thrust-Measurement Methodology Incorporating New Anti-Thrust Hypothesis

    NASA Technical Reports Server (NTRS)

    Ashpis, David E.; Laun, Matthew C.

    2014-01-01

    We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a large diameter, grounded, metal sleeve.

  16. Separation of sources in radiofrequency measurements of partial discharges using time-power ratio maps.

    PubMed

    Albarracin, R; Robles, G; Martinez-Tarifa, J M; Ardila-Rey, J

    2015-09-01

    Partial discharges measurement is one of the most useful tools for condition monitoring of high-voltage (HV) equipment. These phenomena can be measured on-line in radiofrequency (RF) with sensors such as the Vivaldi antenna, used in this paper, which improves the signal-to-noise ratio by rejecting FM and low-frequency TV bands. Additionally, the power ratios (PR), a signal-processing technique based on the power distribution of the incoming signals in frequency bands, are used to characterize different sources of PD and electromagnetic noise (EMN). The calculation of the time length of the pulses is introduced to separate signals where the PR alone do not give a conclusive solution. Thus, if several EM sources could be previously calibrated, it is possible to detect pulses corresponding to PD activity. PMID:25997372

  17. Measurement of mass, momentum and energy distributions in a quasi-steady MPD discharge.

    NASA Technical Reports Server (NTRS)

    Clark, K. E.; Jahn, R. G.; Von Jaskowsky, W. F.

    1972-01-01

    Piezoelectric impact pressure measurements in the exhaust flow of a quasi-steady MPD accelerator are used to compute the profile of momentum flux 25.4 cm downstream of a 2.8 MW discharge. The integral of this profile is in good agreement with the sum of calculated electromagnetic and measured electrothermal thrust components. Velocity vector profiles obtained by a time-of-flight technique reveal a radial variation of velocity ranging from 31,000 m/sec on the centerline to 11,000 m/sec at a radius of 20 cm. When combined with the momentum flux profiles, these velocities yield information on the distribution of mass and energy in the plasma exhaust.

  18. Axial segregation in high intensity discharge lamps measured by laser absorption spectroscopy

    SciTech Connect

    Flikweert, A.J.; Nimalasuriya, T.; Groothuis, C.H.J.M.; Kroesen, G.M.W.; Stoffels, W.W.

    2005-10-01

    High intensity discharge lamps have a high efficiency. These lamps contain rare-earth additives (in our case dysprosium iodide) which radiate very efficiently. A problem is color separation in the lamp because of axial segregation of the rare-earth additives, caused by diffusion and convection. Here two-dimensional atomic dysprosium density profiles are measured by means of laser absorption spectroscopy; the order of magnitude of the density is 10{sup 22} m{sup -3}. The radially resolved atomic density measurements show a hollow density profile. In the outer parts of the lamp molecules dominate, while the center is depleted of dysprosium atoms due to ionization. From the axial profiles the segregation parameter is determined. It is shown that the lamp operates on the right-hand side of the Fischer curve [J. Appl. Phys. 47, 2954 (1976)], i.e., a larger convection leads to less segregation.

  19. Calibration and use of continuous heat-type automated seepage meters for submarine groundwater discharge measurements

    NASA Astrophysics Data System (ADS)

    Mwashote, B. M.; Burnett, W. C.; Chanton, J.; Santos, I. R.; Dimova, N.; Swarzenski, P. W.

    2010-03-01

    Submarine groundwater discharge (SGD) assessments were conducted both in the laboratory and at a field site in the northeastern Gulf of Mexico, using a continuous heat-type automated seepage meter (seepmeter). The functioning of the seepmeter is based on measurements of a temperature gradient in the water between downstream and upstream positions in its flow pipe. The device has the potential of providing long-term, high-resolution measurements of SGD. Using a simple inexpensive laboratory set-up, we have shown that connecting an extension cable to the seepmeter has a negligible effect on its measuring capability. Similarly, the observed influence of very low temperature (≤3 °C) on seepmeter measurements can be accounted for by conducting calibrations at such temperatures prior to field deployments. Compared to manual volumetric measurements, calibration experiments showed that at higher water flow rates (>28 cm day -1 or cm 3 cm -2 day -1) an analog flowmeter overestimated flow rates by ≥7%. This was apparently due to flow resistance, turbulence and formation of air bubbles in the seepmeter water flow tubes. Salinity had no significant effect on the performance of the seepmeter. Calibration results from fresh water and sea water showed close agreement at a 95% confidence level significance between the data sets from the two media ( R2 = 0.98). Comparatively, the seepmeter SGD measurements provided data that are comparable to manually-operated seepage meters, the radon geochemical tracer approach, and an electromagnetic (EM) seepage meter.

  20. Calibration and use of continuous heat-type automated seepage meters for submarine groundwater discharge measurements

    USGS Publications Warehouse

    Mwashote, B.M.; Burnett, W.C.; Chanton, J.; Santos, I.R.; Dimova, N.; Swarzenski, P.W.

    2010-01-01

    Submarine groundwater discharge (SGD) assessments were conducted both in the laboratory and at a field site in the northeastern Gulf of Mexico, using a continuous heat-type automated seepage meter (seepmeter). The functioning of the seepmeter is based on measurements of a temperature gradient in the water between downstream and upstream positions in its flow pipe. The device has the potential of providing long-term, high-resolution measurements of SGD. Using a simple inexpensive laboratory set-up, we have shown that connecting an extension cable to the seepmeter has a negligible effect on its measuring capability. Similarly, the observed influence of very low temperature (???3 ??C) on seepmeter measurements can be accounted for by conducting calibrations at such temperatures prior to field deployments. Compared to manual volumetric measurements, calibration experiments showed that at higher water flow rates (>28 cm day-1 or cm3 cm-2 day-1) an analog flowmeter overestimated flow rates by ???7%. This was apparently due to flow resistance, turbulence and formation of air bubbles in the seepmeter water flow tubes. Salinity had no significant effect on the performance of the seepmeter. Calibration results from fresh water and sea water showed close agreement at a 95% confidence level significance between the data sets from the two media (R2 = 0.98). Comparatively, the seepmeter SGD measurements provided data that are comparable to manually-operated seepage meters, the radon geochemical tracer approach, and an electromagnetic (EM) seepage meter. ?? 2009 Elsevier Ltd.

  1. The Himalayas of Nepal, a natural laboratory for the search and measurement of CO2 discharge

    NASA Astrophysics Data System (ADS)

    Girault, Frédéric; Koirala, Bharat P.; Bhattarai, Mukunda; Rajaure, Sudhir; Richon, Patrick; Perrier, Frédéric

    2010-05-01

    Large CO2 flux has been found in the Trisuli Valley, North of Kathmandu, Central Nepal, in 2005. This leakage zone is located in the vicinity of the Syabru-Bensi hot springs, and is characterized by an average flux of CO2 of 6500±1100 g m-2 day-1 over an area of 15 m × 15 m (Perrier et al., Earth and Planetary Science Letters, 2009). The site is also located close to the Main Central Thrust Zone (MCT Zone), one of the large Himalayan thrust, connected at depth to the Main Himalayan Thrust, the main thrust currently accommodating the India-Tibet collision (Bollinger et al., Journal of Geophysical Research, 2004). Isotopic carbon ratios (δ13C) indicate that this CO2 may come from metamorphic reactions at about 15 km of depth (Becker et al., Earth and Planetary Science Letters, 2008; Evans et al., Geochemistry Geophysics Geosystems, 2008). Actually, this zone was originally found because of the large δ13C found in the water of the hot springs suggesting degassing (Evans et al., Geochemistry Geophysics Geosystems, 2008). In 2007, another zone of CO2 discharge was discovered 250 m away from the main Syabru-Bensi hot springs. This new zone, located next to the road and easy to access all over the year, was intensely studied, from the end of 2007 to the beginning of 2009. In this zone, an average value of CO2 flux of 1700±300 g m-2 d-1 was obtained over an area of about 40 m × 10 m. Using CO2 flux data from repeated measurements, similar flux values were observed during the dry winter season and the wet summer period (monsoon) (Girault et al., Journal of Environmental Radioactivity, 2009). Thus, in addition to fundamental issues related to global CO2 balance in orogenic belts and tectonically active zones, these small scale (100-meter) CO2 discharge sites emerge as a potentially useful laboratory for detailed methodological studies of diffusive and advective gas transport. Recently, the search for further gas discharge zones has been carried out using various clues

  2. Measurements of kinetic processes in a self-sustained discharge XeF laser

    NASA Technical Reports Server (NTRS)

    Gower, M. C.; Exberger, R.; Rowley, P. D.; Billman, K. W.

    1978-01-01

    Measurements are presented for processes occurring in XeF self-sustained discharges including fluorescence, gain, and absorption at different wavelengths as a function of F2, Xe, and He partial pressures. Time-correlated oscillograms are given for the laser discharge current, metastable XeF small-signal gain at 351.1 nm, transient absorptions at 333.6 and 363.8 nm, metastable-XeF B-state sidelight emission at about 350 nm, metastable-F emission at 634.8 nm, and metastable-F emission at 731.1 nm. It is found that He atoms are necessary for the production of metastable-XeF in its lower vibrational levels and that radiative processes and He quenching are the primary mechanisms for metastable-XeF decay. For small-signal gains of as low as about 8%/cm, the transient absorption at the laser wavelength may be as large as about 1-2%/cm.

  3. Spatially resolved spectroscopic measurements of a dielectric barrier discharge plasma jet applicable for soft ionization

    NASA Astrophysics Data System (ADS)

    Olenici-Craciunescu, S. B.; Müller, S.; Michels, A.; Horvatic, V.; Vadla, C.; Franzke, J.

    2011-03-01

    An atmospheric pressure microplasma ionization source based on a dielectric barrier discharge with a helium plasma cone outside the electrode region has been developed for liquid chromatography/mass spectrometry and as ionization source for ion mobility spectrometry. It turned out that dielectric barrier discharge ionization could be regarded as a soft ionization technique characterized by only minor fragmentation similar to atmospheric pressure chemical ionization (APCI). Mainly protonated molecules were detected. In order to characterize the soft ionization mechanism spatially resolved optical emission spectrometry (OES) measurements were performed on plasma jets burning either in He or in Ar. Besides to spatial intensity distributions of noble gas spectral lines, in both cases a special attention was paid to lines of N 2+ and N 2. The obtained mapping of the plasma jet shows very different number density distributions of relevant excited species. In the case of helium plasma jet, strong N 2+ lines were observed. In contrast to that, the intensities of N 2 lines in Ar were below the present detection limit. The positions of N 2+ and N 2 distribution maxima in helium indicate the regions where the highest efficiency of the water ionization and the protonation process is expected.

  4. Discharge probability measurement of a Triple GEM detector irradiated with neutrons

    NASA Astrophysics Data System (ADS)

    Croci, G.; Alfonsi, M.; Ropelewski, L.; Tsipolitis, G.; Fanourakis, G.; Ntomari, E.; Karakostas, K.

    2013-06-01

    Neutron GEM-based detectors represent a new frontier of diagnostic devices in neutron-linked physics applications such as detectors for fusion experiments (Croci et al., 2012 [1]) and spallation sources (Murtas et al., 2012 [2]). Besides, detectors installed in HEP experiments (like LHC at CERN) are dip in a high flux neutron field. For example, the TOTEM T2 GEM telescope (Bagliesi et al., 2010 [3]) at LHC is currently installed very close to the beam pipe where a high intensity (>104 n cm-2 s-1) neutron background is present. In order to assess the capability (particularly related to discharge probability) of working in intense neutrons environment, a 10×10 cm2 Triple GEM detector has been tested using a high flux (105 n cm-2 s-1) neutron beam. The neutron-induced discharge probability PDisch was measured to be 1.37×10-7 at an effective gain G=5×104. In addition, the different types of neutron interactions within the detector were fully explained through a GEANT4 simulation.

  5. Measurement of electron density transients in pulsed RF discharges using a frequency boxcar hairpin probe

    NASA Astrophysics Data System (ADS)

    Peterson, David; Coumou, David; Shannon, Steven

    2015-11-01

    Time resolved electron density measurements in pulsed RF discharges are shown using a hairpin resonance probe using low cost electronics, on par with normal Langmuir probe boxcar mode operation. Time resolution of 10 microseconds has been demonstrated. A signal generator produces the applied microwave frequency; the reflected waveform is passed through a directional coupler and filtered to remove the RF component. The signal is heterodyned with a frequency mixer and rectified to produce a DC signal read by an oscilloscope. At certain points during the pulse, the plasma density is such that the applied frequency is the same as the resonance frequency of the probe/plasma system, creating reflected signal dips. The applied microwave frequency is shifted in small increments in a frequency boxcar routine to determine the density as a function of time. A dc sheath correction is applied for the grounded probe, producing low cost, high fidelity, and highly reproducible electron density measurements. The measurements are made in both inductively and capacitively coupled systems, the latter driven by multiple frequencies where a subset of these frequencies are pulsed. Measurements are compared to previous published results, time resolved OES, and in-line measurement of plasma impedance. This work is supported by the NSF DOE partnership on plasma science, the NSF GOALI program, and MKS Instruments.

  6. Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors

    NASA Astrophysics Data System (ADS)

    Revilla-Romero, B.; Thielen, J.; Salamon, P.; De Groeve, T.; Brakenridge, G. R.

    2014-11-01

    One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real-time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing signal of the Global Flood Detection System for converting the flood detection signal into river discharge values. The study uses data for 322 river measurement locations in Africa, Asia, Europe, North America and South America. Satellite discharge measurements were calibrated for these sites and a validation analysis with in situ discharge was performed. The locations with very good performance will be used in a future project where satellite discharge measurements are obtained on a daily basis to fill the gaps where real-time ground observations are not available. These include several international river locations in Africa: the Niger, Volta and Zambezi rivers. Analysis of the potential factors affecting the satellite signal was based on a classification decision tree (random forest) and showed that mean discharge, climatic region, land cover and upstream catchment area are the dominant variables which determine good or poor performance of the measurement sites. In general terms, higher skill scores were obtained for locations with one or more of the following characteristics: a river width higher than 1km; a large floodplain area and in flooded forest, a potential flooded area greater than 40%; sparse vegetation, croplands or grasslands and closed to open and open forest; leaf area index > 2; tropical climatic area; and without hydraulic infrastructures. Also, locations where river ice cover is seasonally present obtained higher skill scores. This work provides guidance on the best locations and limitations

  7. Evaluation of the satellite-based Global Flood Detection System for measuring river discharge: influence of local factors

    NASA Astrophysics Data System (ADS)

    Revilla-Romero, B.; Thielen, J.; Salamon, P.; De Groeve, T.; Brakenridge, G. R.

    2014-07-01

    One of the main challenges for global hydrological modelling is the limited availability of observational data for calibration and model verification. This is particularly the case for real time applications. This problem could potentially be overcome if discharge measurements based on satellite data were sufficiently accurate to substitute for ground-based measurements. The aim of this study is to test the potentials and constraints of the remote sensing signal of the Global Flood Detection System for converting the flood detection signal into river discharge values. The study uses data for 322 river measurement locations in Africa, Asia, Europe, North America and South America. Satellite discharge measurements were calibrated for these sites and a validation analysis with in situ discharge was performed. The locations with very good performance will be used in a future project where satellite discharge measurements are obtained on a daily basis to fill the gaps where real time ground observations are not available. These include several international river locations in Africa: Niger, Volta and Zambezi rivers. Analysis of the potential factors affecting the satellite signal was based on a classification decision tree (Random Forest) and showed that mean discharge, climatic region, land cover and upstream catchment area are the dominant variables which determine good or poor performance of the measurement sites. In general terms, higher skill scores were obtained for locations with one or more of the following characteristics: a river width higher than 1 km; a large floodplain area and in flooded forest; with a potential flooded area greater than 40%; sparse vegetation, croplands or grasslands and closed to open and open forest; Leaf Area Index > 2; tropical climatic area; and without hydraulic infrastructures. Also, locations where river ice cover is seasonally present obtained higher skill scores. The work provides guidance on the best locations and limitations

  8. Municipal wastewater characteristics in Thailand and effects of soft intervention measures in households on pollutant discharge reduction.

    PubMed

    Tsuzuki, Y; Koottatep, T; Jiawkok, S; Saengpeng, S

    2010-01-01

    In developing countries with large Millennium Development Goals (MDGs) sanitation indicator, pollutant discharge reduction function of wastewater treatment systems should be considered. In this paper, pollutant generations per capita (PGCs) and pollutant discharges per capita (PDCs) are estimated as a base dataset for wastewater management in Thailand. PDCs of black water, i.e. toilet wastewater, are found to be much smaller than PGCs of black water. However, PDCs of gray water, i.e. municipal wastewater other than toilet wastewater are large. Gray water is often discharged without treatment and contributes much to ambient water deterioration. Moreover, possible 5-day biological oxygen demand (BOD5) discharge reductions with "soft interventions", i.e. measurements in households to reduce wastewater pollutant discharge such as using a paper filter or a plastic net in kitchen sinks and so on, are estimated as 39, 21 and 34% for BOD5, total Kjeldahl nitrogen (TKN) and phosphate (PO4-P), respectively. For the estimation, environmental accounting housekeeping (EAH) books of domestic wastewater, spreadsheets with pollutant discharges by water usages and possible effects of "soft interventions" are applied. The framework of this study with "soft intervention" effects on pollutant discharge reductions should enhance wastewater management especially in the areas under development of wastewater treatment systems. PMID:20651426

  9. Sentiment Measured in Hospital Discharge Notes Is Associated with Readmission and Mortality Risk: An Electronic Health Record Study

    PubMed Central

    McCoy, Thomas H.; Castro, Victor M.; Cagan, Andrew; Roberson, Ashlee M.; Kohane, Isaac S.; Perlis, Roy H.

    2015-01-01

    Natural language processing tools allow the characterization of sentiment–that is, terms expressing positive and negative emotion–in text. Applying such tools to electronic health records may provide insight into meaningful patient or clinician features not captured in coded data alone. We performed sentiment analysis on 2,484 hospital discharge notes for 2,010 individuals from a psychiatric inpatient unit, as well as 20,859 hospital discharges for 15,011 individuals from general medical units, in a large New England health system between January 2011 and 2014. The primary measures of sentiment captured intensity of subjective positive or negative sentiment expressed in the discharge notes. Mean scores were contrasted between sociodemographic and clinical groups in mixed effects regression models. Discharge note sentiment was then examined for association with risk for readmission in Cox regression models. Discharge notes for individuals with greater medical comorbidity were modestly but significantly lower in positive sentiment among both psychiatric and general medical cohorts (p<0.001 in each). Greater positive sentiment at discharge was associated with significantly decreased risk of hospital readmission in each cohort (~12% decrease per standard deviation above the mean). Automated characterization of discharge notes in terms of sentiment identifies differences between sociodemographic groups, as well as in clinical outcomes, and is not explained by differences in diagnosis. Clinician sentiment merits investigation to understand why and how it reflects or impacts outcomes. PMID:26302085

  10. Sentiment Measured in Hospital Discharge Notes Is Associated with Readmission and Mortality Risk: An Electronic Health Record Study.

    PubMed

    McCoy, Thomas H; Castro, Victor M; Cagan, Andrew; Roberson, Ashlee M; Kohane, Isaac S; Perlis, Roy H

    2015-01-01

    Natural language processing tools allow the characterization of sentiment--that is, terms expressing positive and negative emotion--in text. Applying such tools to electronic health records may provide insight into meaningful patient or clinician features not captured in coded data alone. We performed sentiment analysis on 2,484 hospital discharge notes for 2,010 individuals from a psychiatric inpatient unit, as well as 20,859 hospital discharges for 15,011 individuals from general medical units, in a large New England health system between January 2011 and 2014. The primary measures of sentiment captured intensity of subjective positive or negative sentiment expressed in the discharge notes. Mean scores were contrasted between sociodemographic and clinical groups in mixed effects regression models. Discharge note sentiment was then examined for association with risk for readmission in Cox regression models. Discharge notes for individuals with greater medical comorbidity were modestly but significantly lower in positive sentiment among both psychiatric and general medical cohorts (p<0.001 in each). Greater positive sentiment at discharge was associated with significantly decreased risk of hospital readmission in each cohort (~12% decrease per standard deviation above the mean). Automated characterization of discharge notes in terms of sentiment identifies differences between sociodemographic groups, as well as in clinical outcomes, and is not explained by differences in diagnosis. Clinician sentiment merits investigation to understand why and how it reflects or impacts outcomes. PMID:26302085

  11. Spectroscopic measurement of radiation of high-pressure mercury discharge lamps

    SciTech Connect

    Fu Ling; Leutz, Ralf; Ries, Harald

    2005-06-15

    Compact size and high efficiency are important features for projection systems. As the most often used sources for projection optics, short arc lamps are characterized by their impressive economy and the ability to produce extremely bright light from small dimensional sources. In this contribution the old principle of back reflection towards the sources is applied to a high-pressure mercury discharge lamp with a reflector to improve the radiance of the source by 35% at a certain reduced solid angle. Increasing the optical thickness of sources is equivalent to reducing the total phase space (etendue) of emitted radiation by the same factor, which is very useful for compacting sources. In addition, by comparing the forward radiation and the back-reflected radiation obtained from spectroscopic measurements, we calculate the absorptivity, emissivity, absorption, and emission coefficients of the plasma of the arc lamp based on Kirchhoff's Law and Planck's equation which is necessary for determining its temperature and pressure.

  12. VUV irradiance measurement of a 2.45 GHz microwave-driven hydrogen discharge

    NASA Astrophysics Data System (ADS)

    Komppula, J.; Tarvainen, O.; Kalvas, T.; Koivisto, H.; Kronholm, R.; Laulainen, J.; Myllyperkiö, P.

    2015-09-01

    Absolute values of VUV-emission of a 2.45 GHz microwave-driven hydrogen discharge are reported. The measurements were performed with a robust and straightforward method based on a photodiode and optical filters. It was found that the volumetric photon emission rate in the VUV-range (80-250 nm) is 1016-1017 cm-3 s-1, which corresponds to approximately 8% dissipation of injected microwave power by VUV photon emission. The volumetric emission of characteristic emission bands was utilized to diagnostics of molecular plasma processes including volumetric rates of ionization, dissociation and excitation to high vibrational levels and metastable states. The estimated reaction rates imply that each injected molecule experiences several inelastic electron impact collisions. The upper limit for the total density of metastable neutrals (2S atoms and {{c}3}{{\\Pi}u} molecules) was estimated to be approximately 0.5% of the neutral gas density.

  13. Potential structure of discharge plasma inside liquid directly measured by an electrostatic probe

    SciTech Connect

    Chen, Qiang; Hatakeyama, Rikizo; Kaneko, Toshiro

    2013-06-17

    Potential structures of a discharge plasma inside a liquid are investigated by an electrostatic probe measurement. The time evolution of radial profiles of the floating potential for the plasma inside liquid reveals that the dominant negative charges in the plasma are the negative ion species such as OH{sup -} and O{sub 2}{sup -} rather than electrons. In addition, a positive potential gradient exists at the plasma-liquid interface due to the presence of an electrical double layer which is caused by the separation of low-mass positive ion of H{sup +} and high-mass negative ions of OH{sup -} and O{sub 2}{sup -} near the plasma-liquid interface.

  14. Temperature measurements in arc-discharge synthesis of nanomaterials dedicated for medical applications

    NASA Astrophysics Data System (ADS)

    Raniszewski, Grzegorz

    2013-02-01

    The article presents the plasma synthesis method of carbon nanotubes using an electric arc discharge. In this method different carbon nanotubes are produced as a cathode deposit growth or are deposed on various substrates such as silicon, metals and other materials. The examples of applications of carbon nanotubes in medical applications were presented. Conditions required for the synthesis of carbon nanotubes and process parameters were mentioned. Applications of carbon nanotubes for cancer treatment were discussed. The method of temperature measurement of the arc was described. Contribution to the Topical Issue "13th International Symposium on High Pressure Low Temperature Plasma Chemistry (Hakone XIII)", Edited by Nicolas Gherardi, Henryca Danuta Stryczewska and Yvan Ségui.

  15. A lower dimensional feature vector for identification of partial discharges of different origin using time measurements

    NASA Astrophysics Data System (ADS)

    Evagorou, Demetres; Kyprianou, Andreas; Lewin, Paul L.; Stavrou, Andreas; Georghiou, George E.

    2012-05-01

    Partial discharge (PD) classification into sources of different origin is essential in evaluating the severity of the damage caused by its activity on the insulation of power cables and their accessories. More specifically, some types of PD can be classified as having a detrimental effect on the integrity of the insulation while others can be deemed relatively harmless, rendering the correct classification of different PD types of vital importance to electrical utilities. In this work, a feature vector was proposed based on higher order statistics on selected nodes of the wavelet packet transform (WPT) coefficients of time domain measurements, which can compactly represent the characteristics of different PD sources. To assess its performance, experimental data acquired under laboratory conditions for four different PD sources encountered in power systems were used. The two learning machine methods, namely the support vector machine and the probabilistic neural network, employed as the classification algorithms, achieved overall classification rates of around 98%. In comparison, the utilization of the scaled, raw WPT coefficients as a feature vector resulted in classification accuracy of around 99%, but with a significantly higher number of dimensions (1304 to 16), validating the PD identification ability of the proposed feature. Dimensionality reduction becomes a key factor in online, real-time data collection and processing of PD measurements, reducing the classification effort and the data-storage requirements. Therefore, the proposed method can constitute a potential tool for such online measurements, after addressing issues related to on-site measurements such as the rejection of interference.

  16. NO density and gas temperature measurements in atmospheric pressure nanosecond repetitively pulsed (NRP) discharges by Mid-IR QCLAS

    NASA Astrophysics Data System (ADS)

    Simeni Simeni, Marien; Stancu, Gabi-Daniel; Laux, Christophe

    2014-10-01

    Nitric oxide is a key species for many processes: in combustion, in human skin physiology... Recently, NO-ground state absolute density measurements produced by atmospheric pressure NRP discharges were carried out in air as a function of the discharge parameters, using Quantum Cascade Laser Absorption Spectroscopy. These measurements were space averaged and performed in the post-discharge region in a large gas volume. Here we present radial profiles of NO density and temperature measured directly in the discharge for different configurations. Small plasma volume and species densities, high temperature and EM noise environment make the absorption diagnostic challenging. For this purpose the QCLAS sensitivity was improved using a two-detector system. We conducted lateral absorbance measurements with a spatial resolution of 300 μm for two absorption features at 1900.076 and 1900.517 cm-1. The radial temperature and NO density distributions were obtained from the Abel inverted lateral measurements. Time averaged NO densities of about 1.E16 cm-3 and gas temperature of about 1000K were obtained in the center of the discharge. PLASMAFLAME Project (Grant No ANR-11-BS09-0025).

  17. Near Discharge Cathode Assembly Plasma Potential Measurements in a 30-cm NSTAR Type Ion Engine During Beam Extraction

    NASA Technical Reports Server (NTRS)

    Herman, Daniel A.; Gallimore, Alec D.

    2006-01-01

    Floating emissive probe plasma potential data are presented over a two-dimensional array of locations in the near Discharge Cathode Assembly (DCA) region of a 30-cm diameter ring-cusp ion thruster. Discharge plasma data are presented with beam extraction at throttling conditions comparable to the NASA TH Levels 8, 12, and 15. The operating conditions of the Extended Life Test (ELT) of the Deep Space One (DS1) flight spare ion engine, where anomalous discharge keeper erosion occurred, were TH 8 and TH 12 consequently they are of specific interest in investigating discharge keeper erosion phenomena. The data do not validate the presence of a potential hill plasma structure downstream of the DCA, which has been proposed as a possible erosion mechanism. The data are comparable in magnitude to data taken by other researchers in ring-cusp electron-bombardment ion thrusters. The plasma potential structures are insensitive to thruster throttling level with a minimum as low as 14 V measured at the DCA exit plane and increasing gradually in the axial direction. A sharp increase in plasma potential to the bulk discharge value of 26 to 28 volts, roughly 10 mm radially from DCA centerline, was observed. Plasma potential measurements indicate a low-potential plume structure that is roughly 20 mm in diameter emanating from the discharge cathode that may be attributed to a free-standing plasma double layer.

  18. Fast surface temperature measurement of Teflon propellant-in-pulsed ablative discharges using HgCdTe photovoltaic cells

    SciTech Connect

    Antonsen, Erik L.; Burton, Rodney L.; Reed, Garrett A.; Spanjers, Gregory G.

    2006-10-15

    High-speed mercury cadmium telluride photovoltaic detectors, sensitive to infrared emission, are investigated as a means of measuring surface temperature on a microsecond time frame during pulsed ablative discharges with Teflon trade mark sign as the ablated material. Analysis is used to derive a governing equation for detector output voltage for materials with wavelength dependent emissivity. The detector output voltage is experimentally calibrated against thermocouples embedded in heated Teflon. Experimental calibration is performed with Teflon that has been exposed to {approx}200 pulsed discharges and non-plasma-exposed Teflon and is compared to theoretical predictions to analyze emissivity differences. The diagnostic capability is evaluated with measurements of surface temperature from the Teflon propellant of electric micropulsed plasma thrusters. During the pulsed current discharge, there is insufficient information to claim that the surface temperature is accurately measured. However, immediately following the discharge, the postpulse cooling curve is measured. The statistical spread of postpulse surface temperature from shot to shot, most likely due to arc constriction and localization, is investigated to determine an operational envelope for postpulse temperature and mass ablation. This information is useful for determining postpulse ablation contributions to mass loss as well as evaluation of theoretical discharge models currently under development.

  19. Thrust Stand Measurements Using Alternative Propellants in the Microwave Assisted Discharge Inductive Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.

    2011-01-01

    Storable propellants (for example water, ammonia, and hydrazine) are attractive for deep space propulsion due to their naturally high density at ambient interplanetary conditions, which obviates the need for a cryogenic/venting system. Water in particular is attractive due to its ease of handling and availability both terrestrially and extra-terrestrially. While many storable propellants are reactive and corrosive, a propulsion scheme where the propellant is insulated from vulnerable (e.g. metallic) sections of the assembly would be well-suited to process these otherwise incompatible propellants. Pulsed inductive plasma thrusters meet this criterion because they can be operated without direct propellant-electrode interaction. During operation of these devices, electrical energy is capacitively stored and then discharged through an inductive coil creating a time-varying current in the coil that interacts with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, many pulsed inductive plasma thrusters require high pulse energies to inductively ionize propellant. The Microwave Assisted Discharge Inductive Plasma Accelerator (MAD-IPA) is a pulsed inductive plasma thruster that addressees this issue by partially ionizing propellant inside a conical inductive coil before the main current pulse via an electron cyclotron resonance (ECR) discharge. The ECR plasma is produced using microwaves and a static magnetic field from a set of permanent magnets arranged to create a thin resonance region along the inner surface of the coil, restricting plasma formation, and in turn current sheet formation, to a region where the magnetic coupling between the plasma and the theta

  20. Electric Field Measurements in Non-Equilibrium Electric Discharge Plasmas Using Picosecond Four-Wave Mixing

    NASA Astrophysics Data System (ADS)

    Goldberg, Benjamin M.

    This dissertation presents the results of development of a picosecond four wave mixing technique and its use for electric field measurements in nanosecond pulse discharges. This technique is similar to coherent anti-Stokes Raman spectroscopy and is well suited for electric field measurements in high pressure plasmas with high spatial and temporal resolution. The results show that the signal intensity scales proportionally to the square of the electric field, the signal is emitted as a coherent beam, and is polarized parallel to the electric field vector, making possible electric field vector component measurements. The signal is generated when a collinear pair of pump and Stokes beams, which are generated in a stimulated Raman shifting cell (SRS), generate coherent excitation of molecules into a higher energy level, hydrogen for the present work. The coherent excitation mixes with a dipole moment induced by an external electric field. The mixing of these three "waves'" allows the molecules to radiate at their Raman frequency, producing a fourth, signal, wave which is proportional to the square of the electric field. The time resolution of this technique is limited by the coherence decay time of the molecules, which is a few hundred picoseconds.

  1. Rare measurements of a sprite with halo event driven by a negative lightning discharge over Argentina

    USGS Publications Warehouse

    Taylor, M.J.; Bailey, M.A.; Pautet, P.D.; Cummer, S.A.; Jaugey, N.; Thomas, J.N.; Solorzano, N.N.; Sao, Sabbas F.; Holzworth, R.H.; Pinto, O.; Schuch, N.J.

    2008-01-01

    As part of a collaborative campaign to investigate Transient Lummous Events (TLEs) over South America, coordinated optical, ELF/VLF, and lightning measurements were made of a mesoscale thunderstorm observed on February 22-23, 2006 over northern Argentina that produced 445 TLEs within a ???6 hour period. Here, we report comprehensive measurements of one of these events, a sprite with halo that was unambiguously associated with a large negative cloud-to-ground (CG) lightning discharge with an impulsive vertical charge moment change (??MQv) of -503 C.km. This event was similar in its location, morphology and duration to other positive TLEs observed from this storm. However, the downward extent of the negative streamers was limited to 25 km, and their apparent brightness was lower than that of a comparable positive event. Observations of negative CG events are rare, and these measurements provide fin-ther evidence that sprites can be driven by upward as well as downward electric fields, as predicted by the conventional breakdown mechanism. Copyright 2008 by the American Geophysical Union.

  2. Measuring flood discharge in unstable stream channels using ground-penetrating radar

    USGS Publications Warehouse

    Spicer, K.R.; Costa, J.E.; Placzek, G.

    1997-01-01

    Field experiments were conducted to test the ability of ground-penetrating radar (GPR) to measure stream-channel cross sections at high flows without the necessity of placing instruments in the water. Experiments were conducted at four U.S. Geological Survey gaging stations in southwest Washington State. With the GPR antenna suspended above the water surface from a bridge or cableway, traverses were made across stream channels to collect radar profile plots of the streambed. Subsequent measurements of water depth were made using conventional depth-measuring equipment (weight and tape) and were used to calculate radar signal velocities. Other streamflow-parameter data were collected to examine their relation to radar signal velocity and to claritv of streambed definition. These initial tests indicate that GPR is capable of producing a reasonably accurate (??20%) stream-channel profile and discharge far more quickly than conventional stream-gaging procedures, while avoiding the problems and hazards associated with placing instruments in the water.

  3. Comparison of measured and modelled negative hydrogen ion densities at the ECR-discharge HOMER

    NASA Astrophysics Data System (ADS)

    Rauner, D.; Kurutz, U.; Fantz, U.

    2015-04-01

    As the negative hydrogen ion density nH- is a key parameter for the investigation of negative ion sources, its diagnostic quantification is essential in source development and operation as well as for fundamental research. By utilizing the photodetachment process of negative ions, generally two different diagnostic methods can be applied: via laser photodetachment, the density of negative ions is measured locally, but only relatively to the electron density. To obtain absolute densities, the electron density has to be measured additionally, which induces further uncertainties. Via cavity ring-down spectroscopy (CRDS), the absolute density of H- is measured directly, however LOS-averaged over the plasma length. At the ECR-discharge HOMER, where H- is produced in the plasma volume, laser photodetachment is applied as the standard method to measure nH-. The additional application of CRDS provides the possibility to directly obtain absolute values of nH-, thereby successfully bench-marking the laser photodetachment system as both diagnostics are in good agreement. In the investigated pressure range from 0.3 to 3 Pa, the measured negative hydrogen ion density shows a maximum at 1 to 1.5 Pa and an approximately linear response to increasing input microwave powers from 200 up to 500 W. Additionally, the volume production of negative ions is 0-dimensionally modelled by balancing H- production and destruction processes. The modelled densities are adapted to the absolute measurements of nH- via CRDS, allowing to identify collisions of H- with hydrogen atoms (associative and non-associative detachment) to be the dominant loss process of H- in the plasma volume at HOMER. Furthermore, the characteristic peak of nH- observed at 1 to 1.5 Pa is identified to be caused by a comparable behaviour of the electron density with varying pressure, as ne determines the volume production rate via dissociative electron attachment to vibrationally excited hydrogen molecules.

  4. Measurements of the populations of metastable and resonance levels in the plasma of an RF capacitive discharge in argon

    SciTech Connect

    Vasilieva, A. N.; Voloshin, D. G.; Kovalev, A. S. Kurchikov, K. A.

    2015-05-15

    The behavior of the populations of two metastable and two lower resonance levels of argon atoms in the plasma of an RF capacitive discharge was studied. The populations were measured by two methods: the method of emission self-absorption and the method based on measurements of the intensity ratios of spectral lines. It is shown that the populations of resonance levels increase with increasing power deposited in the discharge, whereas the populations of metastable levels is independent of the RF power. The distribution of the populations over energy levels is not equilibrium under these conditions. The population kinetics of argon atomic levels in the discharge plasma is simulated numerically. The distribution function of plasma electrons recovered from the measured populations of atomic levels and numerical simulations is found to be non-Maxwellian.

  5. Thrust Stand Measurements of the Microwave Assisted Discharge Inductive Plasma Accelerator

    NASA Technical Reports Server (NTRS)

    Hallock, Ashley K.; Polzin, Kurt A.; Emsellem, Gregory D.

    2011-01-01

    Pulsed inductive plasma thrusters [1-3] are spacecraft propulsion devices in which electrical energy is capacitively stored and then discharged through an inductive coil. This type of pulsed thruster is electrodeless, with a time-varying current in the coil interacting with a plasma covering the face of the coil to induce a plasma current. Propellant is accelerated and expelled at a high exhaust velocity (O(10-100 km/s)) by the Lorentz body force arising from the interaction of the magnetic field and the induced plasma current. While this class of thruster mitigates the life-limiting issues associated with electrode erosion, pulsed inductive plasma thrusters require high pulse energies to inductively ionize propellant. The Microwave Assisted Dis- charge Inductive Plasma Accelerator (MAD-IPA), shown in Fig. 1, is a pulsed inductive plasma thruster that addressees this issue by partially ionizing propellant inside a conical inductive coil before the main current pulse via an electron cyclotron resonance (ECR) discharge. The ECR plasma is produced using microwaves and a static magnetic field from a set of permanent magnets arranged to create a thin resonance region along the inner surface of the coil, restricting plasma formation, and in turn current sheet formation, to a region where the magnetic coupling between the plasma and the theta-pinch coil is high. The use of a conical theta-pinch coil also serves to provide neutral propellant containment and plasma plume focusing that is improved relative to the more common planar geometry of the Pulsed Inductive Thruster (PIT) [1, 2]. In this paper, we describe thrust stand measurements performed to characterize the performance (specific impulse, thrust efficiency) of the MAD-IPA thruster. Impulse data are obtained at various pulse energies, mass flow rates and inductive coil geometries. Dependencies on these experimental parameters are discussed in the context of the current sheet formation and electromagnetic plasma

  6. Concentration-Discharge Patterns Revealed from High Resolution Nitrate Measurements in Agricultural Landscapes

    NASA Astrophysics Data System (ADS)

    Boland, S. J.; Basu, N. B.

    2012-12-01

    Riverine export of nutrients is a major component of nutrient cycles, particularly with respect to nitrogen; ~ 25 percent of terrestrially applied nitrogen (N) is removed via riverine export. Understanding the patterns in N export during a storm event is critical for developing a conceptual model of the dominant processes and pathways of N transformation, and designing appropriate management strategies to mitigate N pollution in streams and receiving water bodies. Most studies however, are limited by the lack of high-resolution water quality data to elucidate these pathways and mechanisms. We explored concentration-discharge relationships using high-resolution (15 minute) discharge (Q) and nitrate concentration (C) data (measured using an in-situ Nitratax Sonde) at multiple nested scales (from 151.3 km2 to 8900 km2) in two watersheds in Iowa: Clear Creek Watershed and the Raccoon River watershed. Three distinct regimes of nitrate transport were revealed: (1) a linear regime in which C increases with increasing Q, (2) a saturation regime in which C remains constant against increasing Q, and (3) a dilution regime in which concentration decreases as Q increases. The tight clustering of the data along these patterns is indicative of emergent behavior in such human-dominated systems. All three regimes were apparent in the Raccoon River Watershed, while only the saturation and dilution regimes were apparent in the Clear Creek Watershed. We hypothesize that surface flow is dominant in the Clear Creek Watershed leading to a saturation/dilution regimes, while subsurface flow is dominant in the more heavily tile-drained Raccoon River Watershed, leading to the occurrence of all three regimes. A parsimonious model was developed to test the hypothesis and develop C-Q patterns as a function of the partitioning of flow through the different pathways.

  7. An Apparatus for Measuring Rates of Discharge of a Fuel-Injection System

    NASA Technical Reports Server (NTRS)

    Dutee, Francis J

    1941-01-01

    A portable apparatus for rapidly determining rates of discharge of a fuel-injection system is described. Satisfactory operation of this apparatus with injection-pump speeds up to 2400 r.p.m was obtained. Rate-of-discharge tests were made with several cam-plunger-valve injection systems with long injection tubes. A check valve designed to reduce secondary discharges was tested. This check valve was operated with injection-pump speeds up to 2400 r.p.m without the occurrence of large secondary discharges.

  8. Estimating sea-ice coverage, draft, and velocity in Marguerite Bay (Antarctica) using a subsurface moored upward-looking acoustic Doppler current profiler (ADCP)

    NASA Astrophysics Data System (ADS)

    Hyatt, Jason; Visbeck, Martin; Beardsley, Robert C.; Brechner Owens, W.

    2008-02-01

    A technique for the analysis of data from a subsurface moored upward-looking acoustic Doppler current profiler (ADCP) to determine ice coverage, draft and velocity is presented and applied to data collected in Marguerite Bay on the western Antarctic Peninsula shelf. This method provides sea-ice information when no dedicated upward-looking sonar (ULS) data are available. Ice detection is accomplished using windowed variances of ADCP vertical velocity, vertical error velocity, and surface horizontal speed. ADCP signal correlation and backscatter intensity were poor indicators of the presence of ice at this site. Ice draft is estimated using a combination of ADCP backscatter data, atmospheric and oceanic pressure data, and information about the thermal stratification. This estimate requires corrections to the ADCP-derived range for instrument tilt and sound speed profile. Uncertainties of ±0.20 m during midwinter and ±0.40 m when the base of the surface mixed layer is above the ADCP for ice draft are estimated based on: (a) a Monte Carlo simulation, (b) uncertainty in the sound speed correction, and (c) performance of the zero-draft estimate during times of known open water. Ice velocity is taken as the ADCP horizontal velocity in the depth bin specified by the range estimate.

  9. Terahertz measurements of the hot hydronium ion with an extended negative glow discharge

    SciTech Connect

    Yu, Shanshan; Pearson, John C.

    2014-05-10

    Terahertz absorption spectroscopy was employed to detect the ground-state inversion transitions of the hydronium ion (H{sub 3}O{sup +}). The highly excited ions were created with an extended negative glow discharge through a gas mixture of 1 mtorr of H{sub 2}O, 2 mtorr of H{sub 2}, and 12 mtorr of Ar, which allowed observation of transitions with J and K up to 12. In total, 47 transitions were measured in the 0.9-2.0 THz region and 22 of these were observed for the first time. The experimental uncertainties range from 100 to 300 kHz, which are much better than the range 0.3-1.2 MHz reported in previous work. Differences of up to 25.6 MHz were found between the observed positions and the catalog values that have been used for Herschel data analysis of observations of Sagittarius B2(N), NGC 4418, and Arp 220. The new and improved measurements were fit to experimental accuracies with an updated Hamiltonian, and better H{sub 3}O{sup +} predictions are reported to support the proper analysis of astronomical observations by high-resolution spectroscopy telescopes, such as Herschel, SOFIA, and ALMA.

  10. Constraint of the limited information content of discharge measurements on the benefits of rating curve models with increased complexities

    NASA Astrophysics Data System (ADS)

    Van Eerdenbrugh, Katrien; Verhoest, Niko; De Mulder, Tom

    2015-04-01

    Discharge assessment through rating curves is a widespread technique in the field of hydrologic monitoring. In practical applications, this technique often consists of the use of one or multiple power laws, based on rather stringent assumptions concerning the nature of the prevailing flow conditions. In reality, those assumptions are regularly violated, inducing considerable uncertainties in the calculated discharges. It is thus important to estimate the effect of those simplifications when performing an overall uncertainty analysis of rating curve discharges. In this study, different rating curve formulations are compared based on both results of a hydrodynamic model and measured water levels and discharges. The results of a hydrodynamic model are used to justify the applicability of several rating curve models with increased complexity as an alternative for a single power law equation. With the hydrodynamic model, situations are simulated that correspond to steady state conditions and to minimal effect of downstream boundaries. Comparison of simulations results with those of measurement-driven simulations leads to an increased understanding of the rating curve dynamics. It allows for evaluation of rating curve formulations accounting for the influences of hysteresis and backwater effects which are neglected in power law rating curves. Subsequently, the performance of those rating curve models and the identifiability of their parameters are assessed based on available stage-discharge measurements and their accompanying uncertainties as described in literature. This assessment is performed based on the Generalised Likelihood Uncertainty Estimation (GLUE). Rejection criteria to distinguish behavioural from non-behavioural models are defined by uncertainties on both water levels and discharge measurements that envelop measured data points. The results of the hydrodynamic model clearly indicate benefits of adding complexity to the rating curve model, mainly by

  11. Synoptic Discharge, Water-Property, and pH Measurements for Muddy River Springs Area and Muddy River, Nevada, February 7, 2001

    USGS Publications Warehouse

    Beck, David A.; Wilson, Jon W.

    2006-01-01

    On February 7, 2001, synoptic discharge measurements at selected sites along the Muddy River in Nevada, indicated three trends in discharge resulting from contributions of spring discharge, influences of diversionary flow, and contributions from shallow ground water. Effects from diversionary and tributary flow were local in nature and resulted in a net gain of 2.6 cubic feet per second throughout the measured reach. The minor increase in discharge may be the result of contributions from ground-water flow and measurement error. Comparison of 1963 and 2001 discharge measurements within the Muddy River Springs area indicated that discharge rates and trends from these source waters were similar. Along the mainstem of the Muddy River, water-temperature measurements indicated a net decrease of 8.8 degrees Celsius. Water samples collected and analyzed for specific conductance indicated a net increase of 390 microsiemens per centimeter at 25 degrees Celsius, whereas pH measurements remained relatively constant.

  12. Measurements of Large-scale Fluctuations in Flow, Lower Mississippi River, May 2011

    NASA Astrophysics Data System (ADS)

    Oberg, K. A.; Mueller, D. S.; Holmes, R. R.; García, C. M.; Tarrab, L.

    2011-12-01

    In support of its mission to characterize the nation's water resources and in support of other Federal and State agencies, the U.S. Geological Survey (USGS) made detailed measurements of the flow in the Lower Mississippi River from Cairo to New Orleans in the spring of 2011. Record stages and flows were experienced at many locations along the River and rarely used flood control structures and flood mitigation measures were put into operation. The New Madrid Floodway, completed in 1932, was used for the first time since 1937. The Morganza spillway was used for the second time since completion in 1954, having first been used during the 1973 flood. Accurate measurement of flow at Tarbert Landing, MS is vital to the operation of the flood control structures along the Lower Mississippi River. Daily discharge measurements were made by the USGS and the U.S. Army Corps of Engineers (the Corps) using acoustic Doppler current profilers (ADCPs) in order to facilitate the Corps' operation of the Old River Control Structure, the Morganza Spillway, and the Bonnet Carre spillway, in addition to managing levees along this reach of the River. Variations in measured discharges upstream and downstream of these control structures were observed during the flood, leading to uncertainty in decision-making for control-structure operation. In order to determine the cause of these variations, detailed, long-duration (4 hours or more) measurements of flow were made by the USGS using ADCPs and Price AA current meters. Analysis of these measurements indicated that a periodic fluctuation was present in the flow. Although the magnitude of the fluctuation varied from one day to the next, the time period remained nearly constant at approximately 2.5 hours. Measured flow in the Mississippi River at Tarbert Landing fluctuated as much as 9,910 cubic meters per second from a mean flow of approximately 42,500 cubic meters per second, or 23% of the mean measured discharge. Preliminary analysis of ADCP

  13. Improvement of process identification and discharge measurement by the combination of different sensors

    NASA Astrophysics Data System (ADS)

    Schimmel, Andreas; Hübl, Johannes; Koschuch, Richard

    2016-04-01

    the opportunity to measure the surface velocity of a debris flow. Together with a recently installed 2D-Laser Scanner this setup provides the possibility to get a very precise approximation for the discharge. Therefore the cross sectional welted area is multiplied with the mean surface velocity of the related range gate within a time step of one second. This method has already been successfully applied to a debris flow which took place on the 09.08.2015. It was a medium sized event with two surges and a peak discharge of 64 m³/s. The average velocity measured by the high frequency Radar ranges from 0,7 to 4,3 m/s and the cross sectional welted area measured by the 2D Laser was up to 18,6 m². The total debris flow volume over the measurement time of one hour was calculated to ~16.000 m³.

  14. Comparison of measured and modelled negative hydrogen ion densities at the ECR-discharge HOMER

    SciTech Connect

    Rauner, D.; Kurutz, U.; Fantz, U.

    2015-04-08

    As the negative hydrogen ion density n{sub H{sup −}} is a key parameter for the investigation of negative ion sources, its diagnostic quantification is essential in source development and operation as well as for fundamental research. By utilizing the photodetachment process of negative ions, generally two different diagnostic methods can be applied: via laser photodetachment, the density of negative ions is measured locally, but only relatively to the electron density. To obtain absolute densities, the electron density has to be measured additionally, which induces further uncertainties. Via cavity ring-down spectroscopy (CRDS), the absolute density of H{sup −} is measured directly, however LOS-averaged over the plasma length. At the ECR-discharge HOMER, where H{sup −} is produced in the plasma volume, laser photodetachment is applied as the standard method to measure n{sub H{sup −}}. The additional application of CRDS provides the possibility to directly obtain absolute values of n{sub H{sup −}}, thereby successfully bench-marking the laser photodetachment system as both diagnostics are in good agreement. In the investigated pressure range from 0.3 to 3 Pa, the measured negative hydrogen ion density shows a maximum at 1 to 1.5 Pa and an approximately linear response to increasing input microwave powers from 200 up to 500 W. Additionally, the volume production of negative ions is 0-dimensionally modelled by balancing H{sup −} production and destruction processes. The modelled densities are adapted to the absolute measurements of n{sub H{sup −}} via CRDS, allowing to identify collisions of H{sup −} with hydrogen atoms (associative and non-associative detachment) to be the dominant loss process of H{sup −} in the plasma volume at HOMER. Furthermore, the characteristic peak of n{sub H{sup −}} observed at 1 to 1.5 Pa is identified to be caused by a comparable behaviour of the electron density with varying pressure, as n{sub e} determines

  15. Novel method of measuring polymer melt viscosity using a short length of single screw extruder at the closed discharge state

    NASA Astrophysics Data System (ADS)

    Kim, Myung-Ho; Kim, Bo-Kyung; Kang, Seok-Jin; Kim, Moon Sung; Choi, Sunwoong

    2016-03-01

    Theory of single screw extruders has been used for analyzing the processing characteristics of various polymeric fabricated such material as plastics, rubber, and food products. Recently this theory extended to measuring the polymer melt viscosity using the closed discharging state of the short single screw extruder. The batch wise operation of the closed discharged state change the complex extrusion characteristic equation into simple calculation form of shear rate and viscosity equation, which related between the geometrical factors and the screw speed and the axial pressure generation, respectively.

  16. Partial discharge current pulses in SF6 and the effect of superposition of their radiometric measurement

    NASA Astrophysics Data System (ADS)

    Reid, Alistair J.; Judd, Martin D.; Stewart, Brian G.; Fouracre, Richard A.

    2006-10-01

    The practical advantages of employing non-contact radio frequency (RF) methods for detecting partial discharges (PDs) in high voltage equipment have led to significant effort being focused on the diagnosis of electrical plants using RF techniques. This has particularly been the case for gas insulated substations, which use sulphur hexafluoride (SF6) as an insulating medium. One of the most important challenges facing RF diagnostics is the problem of relating the RF emissions to some measure of severity of the PD. Previous work has established that the amplitude or energy of RF signals radiated from a PD source is strongly dependent on the rate of change of current in the PD pulse. In this paper, measurements of PD current pulses in SF6 are presented for a point-plane configuration using an extremely wide bandwidth (13 GHz) measurement system. By this means, PD pulse shapes have been recorded with better resolution than has previously been possible and rise times have been measured with a high degree of accuracy. The results show a considerable variation in pulse shape, with the minimum rise time measured being 35 ps. With this high time-domain resolution, we have been able to distinguish features within the PD pulses that will affect the energy of the radiated RF signal. In particular, the current pulses tend to occur in bursts of up to ten individual pulses in as little as 1 ns, which will excite multiple RF signals in rapid succession. The effect of superposition of RF waveforms has been investigated by studying the variation in detected RF energy with respect to the time delay between PD pulses. It was found that when two PDs occur within a short period (< 150 ns) the combined energy of the resulting RF pulse has the potential to vary by ±30% of that resulting from two equivalent PD pulses with a wider pulse spacing (Gt 150 ns). In terms of a practical monitoring system concerned with order-of-magnitude variations; this is not considered to pose a major problem

  17. Terahertz Measurements of Hot Hydronium Ions (H_3O^+) with AN Extended Negative Glow Discharge

    NASA Astrophysics Data System (ADS)

    Yu, Shanshan; Pearson, John

    2014-06-01

    Terahertz absorption spectroscopy was employed to detect the ground-state inversion transitions of the hydronium ion. The highly excited ions were created with an extended negative glow discharge through a gas mixture of 1 mtorr of H_2O, 2 mtorr of H_2, and 12 mtorr of Ar, which allowed observation of transitions with J and K up to 12. In total forty seven transitions were measured in the 0.9--2.0 THz region and twenty two of them were observed for the first time. The experimental uncertainties range from 100 to 300 kHz, which are much better than those of 0.3--1.2 MHz reported in previous work. Differences up to 25.6 MHz were found between the observed positions and the catalog values that have been used for Herschel data analysis of observations towards Sagittarius B2(N), NGC 4418 and Arp 220. The new and improved measurements were fit to experimental accuracies with an updated Hamiltonian; and better H_3O^+ predictions are reported to support the proper analysis of astronomical observations by high-resolution spectroscopy telescopes, such as Herschel, SOFIA, and ALMA. Lis et al., '' Hot, metastable hydronium ion in the Galactic center: formation pumping in X-ray-irradiated gas?'', Phil. Trans. R. Soc. A 370, 5162 (2012). González-Alfonso et al., '' Excited OH^+, H_2O^+ and H_3O^+ in NGC 4418 and Arp 220'', Astrophys. Astronom 550, A25 (2013). Lis et al., '' Widespread rotaional-hot hydronium in the Galactic Interstellar Medium'', Astrophys. J., submitted (2014).

  18. Comparison of estimates of uncertainty of discharge at US geological survey index-velocity gages on the Chicago sanitary and ship canal, Illinois

    USGS Publications Warehouse

    Over, T.M.; Duncker, J.J.; Gonzalez-Castro, J. A.

    2004-01-01

    Estimates of uncertainty of discharge at time scales from 5 minutes to 1 year were obtained for two index-velocity gages on the Chicago Sanitary and Ship Canal (CSSC), Ill., instrumented with acoustic velocity meters (AVMs). The velocity measurements obtained from the AVMs are corrected to a mean channel velocity by use of an index velocity rating (IVR). The IVR is a regression-derived relation between the AVM velocity estimates and those obtained using acoustic Doppler current profilers (ADCPs). The uncertainty estimation method is based on the first-order variance method, but the AVM velocity error is estimated from an empirical perspective, using the statistics of the IVR regression. Some uncertainty exists regarding whether to include the standard error of the IVR regression (????2) in the discharge uncertainty. At the 5-minute time scale when ?? ??2 is included, it has the dominant contribution to the discharge uncertainty, and the discharge uncertainty (expressed as the standard deviation of the discharge estimate) is about 5 m3/s at one gage and 8 m3/s at the other, independent of discharge. When ????2 is not included, the discharge uncertainty at the 5-minute time scale is much smaller (about 0.5 m3/s) and depends more strongly on discharge. For time scales one day or greater and when ????2 is not included, the uncertainty of the IVR parameters dominates the discharge uncertainty. The value of the discharge uncertainty is about 0.4 m3/s for one gage and 0.5 m3/s for the other gage at long time scales.

  19. Experimental measurement of spatially resolved electron density in a filament of a pulsed positive streamer discharge in water

    SciTech Connect

    Wen, Xiao Qiong; Niu, Zhi Wen; Ren, Chun-Sheng; Hou, Bo

    2015-06-29

    By combining a high-speed frame camera with a monochromator, the spatially resolved optical emission spectrum of hydrogen α line in a single filament of a pulsed positive streamer discharge in water has been experimentally measured. The spatially resolved electron densities in a single filament of a pulsed positive streamer discharge in water with a conductivity of 200 μS/cm were investigated. During the experiment, the average energy per pulse of discharge was 90.6 ± 13.6 mJ. The results show that the electron density in the streamer filament is 10{sup 17–18}/cm{sup 3}, and present a decreasing tendency along the axial direction of the streamer filament with increasing distance from the tip of the anode.

  20. Vibrational and rotational CARS measurements of nitrogen in afterglow of streamer discharge in atmospheric pressure fuel/air mixtures

    NASA Astrophysics Data System (ADS)

    Pendleton, S. J.; Montello, A.; Carter, C.; Lempert, W.; Gundersen, M. A.

    2012-12-01

    The use of nonequilibrium plasma generated by nanosecond discharges to ignite fuel/air mixtures, known as transient plasma ignition (TPI), has been shown to effectively reduce ignition delay and improve engine performance relative to spark ignition for combustion engines. While this method is potentially useful for many engine applications, at present the underlying physics are poorly understood. This work uses coherent anti-Stokes Raman spectroscopy (CARS) to measure the rotational and vibrational excitation of nitrogen molecules in the discharge afterglow in a variety of fuel/air mixtures outside the limits of combustion in order to elucidate the thermal behaviour of TPI. The time evolution of relative populations of vibrationally excited states of nitrogen in the electronic ground state are reported for each gas mixture; it is shown that generation of these vibrationally excited states is inefficient during the discharge in air but that generation occurs at a high rate roughly 5 µs following the discharge; with the addition of fuels vibrationally excited states are observed during the discharge but an increase in population is still seen at 5 µs. Possible mechanisms for this behaviour are discussed. In addition, rotational temperature increases of at least 500 K are reported for all gas mixtures. The effect of this temperature increase on ignition, reaction rates, and thermal energy pathways are discussed.

  1. An intercomparison of remote sensing river discharge estimation algorithms from measurements of river height, width, and slope

    NASA Astrophysics Data System (ADS)

    Durand, M.; Gleason, C. J.; Garambois, P. A.; Bjerklie, D.; Smith, L. C.; Roux, H.; Rodriguez, E.; Bates, P. D.; Pavelsky, T. M.; Monnier, J.; Chen, X.; Di Baldassarre, G.; Fiset, J.-M.; Flipo, N.; Frasson, R. P. d. M.; Fulton, J.; Goutal, N.; Hossain, F.; Humphries, E.; Minear, J. T.; Mukolwe, M. M.; Neal, J. C.; Ricci, S.; Sanders, B. F.; Schumann, G.; Schubert, J. E.; Vilmin, L.

    2016-06-01

    The Surface Water and Ocean Topography (SWOT) satellite mission planned for launch in 2020 will map river elevations and inundated area globally for rivers >100 m wide. In advance of this launch, we here evaluated the possibility of estimating discharge in ungauged rivers using synthetic, daily "remote sensing" measurements derived from hydraulic models corrupted with minimal observational errors. Five discharge algorithms were evaluated, as well as the median of the five, for 19 rivers spanning a range of hydraulic and geomorphic conditions. Reliance upon a priori information, and thus applicability to truly ungauged reaches, varied among algorithms: one algorithm employed only global limits on velocity and depth, while the other algorithms relied on globally available prior estimates of discharge. We found at least one algorithm able to estimate instantaneous discharge to within 35% relative root-mean-squared error (RRMSE) on 14/16 nonbraided rivers despite out-of-bank flows, multichannel planforms, and backwater effects. Moreover, we found RRMSE was often dominated by bias; the median standard deviation of relative residuals across the 16 nonbraided rivers was only 12.5%. SWOT discharge algorithm progress is therefore encouraging, yet future efforts should consider incorporating ancillary data or multialgorithm synergy to improve results.

  2. A comparative study of mean-section and mid-section methods for computation of discharge measurements

    USGS Publications Warehouse

    Young, Kenneth B.

    1950-01-01

    In February, 1949, Mr. J. V. B. Wells, Chief of the Surface Water Branch, appointed a committee of three hydraulic engineers assigned to the Washington office to make a comparative study of the relative merits of the mean-section and mid-section methods of computing discharge measurements. this was done in order that there might be a basis for either adhering to the present "official" method, or adopting another method as the "official" one. This study is based on a collection of field data consisting of discharge measurements made with approximately four times the usual number of observations. There was a total of 213 of these special measurements made by all the district offices. The two methods of computation were examined as to accuracy and time savings. This was done by selecting observation stations from the special measurements to arrive at a synthetic measurement with the usual number of observations. This normal measurement was then computed by both the mean-section and mid-section method of computation for a comparison of results in discharge. A record was kept of the time consumed for computing and checking measurements so that any time savings in either method could be found. Much of the computation work was done in four of the district offices, with a variety in personnel as to grade and to experience in the use of the two methods.

  3. Applicability of acoustic Doppler devices for flow velocity measurements and discharge estimation in flows with sediment transport

    NASA Astrophysics Data System (ADS)

    Nord, Guillaume; Gallart, Francesc; Gratiot, Nicolas; Soler, Montserrat; Reid, Ian; Vachtman, Dina; Latron, Jérôme; Martín-Vide, Juan Pedro; Laronne, Jonathan B.

    2014-02-01

    Acoustic Doppler devices (Unidata Starflow) have been deployed for velocity measurements and discharge estimates in five contrasted open-channel flow environments, with particular attention given to the influence of sediment transport on instrument performance. The analysis is based on both field observations and flume experiments. These confirm the ability of the Starflow to provide reliable discharge time-series, but point out its limitations when sediment is being transported. (i) After calibration of the instrument by the Index Velocity Method, the deviation from reference discharge measurements was < 20% at the 95% confidence level. (ii) In ungauged conditions at high flows, the Starflow was particularly useful in providing velocity data for approximating measurements of discharge. (iii) However, channel and flume experiments revealed the effects of mobilised sediment on velocity estimates: coarse particles (⩾ 150 μm) transported by way of saltation or as bedload caused a significant underestimation of velocity by as much as 50%; a slight underestimation (10-15%) was also observed when significant quantities of fine particles (⩽150 μm) were transported in suspension; this underestimation was shown to reach 20-30% when suspended sediment concentrations were very high (c. 50-100 g L-1).

  4. Automatic identification and placement of measurement stations for hydrological discharge simulations at basin scale

    NASA Astrophysics Data System (ADS)

    Grassi, P. R.; Ceppi, A.; Cancarè, F.; Ravazzani, G.; Mancini, M.; Sciuto, D.

    2012-04-01

    In the past 15 years hydroinformatics has substantially increased the use of computational intelligence techniques for water distribution network, modelling, and prediction purposes. An application of these technologies is proposed in this study as an advanced algorithm tool to analyze a hydro-meteorological dataset, establishing a skill for numerical modelling, data collection, processing and quality checking. Accurate forecasts of hydro-meteorological events are important to prevent and mitigate the effect of dangerous events such as floods or drought. To achieve these objectives, Politecnico di Milano developed a distributed physically based rainfall-runoff model (FEST-WB), which is daily used to generate runoff simulations and hydrological forecasts for nowcasting monitoring and as a civil-protection tool. It takes, as input, a set of observed meteorological data (solar radiation, precipitation, air temperature and relative humidity) collected by the ARPAP (Environment Protection Regional Agency of Piedmont) hydro-meteorological station network and MeteoSwiss, and it provides, as output, discharge forecasts in various hydrological basins. Although, the performance capability of the model dramatically depends on the model itself, it is a known fact that the choice of right measurement sites play a very crucial role in building quality models; on the other hand, reducing the amount of stations reduce their deployment and maintenance costs. The aim of this study is to apply a set of optimization algorithms in order to identify the minimum number and position of weather stations able to provide correct predictions. This analysis is focused on the Toce river basin, an Alpine watershed, located in North-West of Italy, but the methodology can be extended to other Piedmont areas. The whole set of measured data M are taken as input to provide a set of Pareto-optimal solutions. The configuration is described with a boolean vector where true indicates that the

  5. Submarine groundwater discharge to a small estuary estimated from radon and salinity measurements and a box model

    USGS Publications Warehouse

    Crusius, J.; Koopmans, D.; Bratton, J.F.; Charette, M.A.; Kroeger, K.D.; Henderson, P.; Ryckman, L.; Halloran, K.; Colman, J.A.

    2005-01-01

    Submarine groundwater discharge was quantified by a variety of methods in Salt Pond, adjacent to Nauset Marsh on Cape Cod, USA. Discharge estimates based on radon and salinity took advantage of the presence of the narrow channel connecting Salt Pond to Nauset Marsh, which allowed constructing whole-pond mass balances as water flowed in and out due to tidal fluctuations. A box model was used to estimate discharge separately to Salt Pond and to the channel by simulating the timing and magnitude of variations in the radon and salinity data in the channel. Discharge to the pond is estimated to be 2200??1100 m3 d-1, while discharge to the channel is estimated to be 300??150m3 d-1, for a total discharge of 2500??1250 m3 d-1 to the Salt Pond system. This translates to an average groundwater flow velocity of 3??1.5 cm d -1. Seepage meter flow estimates are broadly consistent with this figure, provided discharge is confined to shallow sediments (water depth <1 m). The radon data can be modeled assuming all groundwater fluxes to both the channel and to the pond are fresh, with no need to invoke a saline component. The absence of a saline component in the radon flux may be due to removal of radon from saline groundwater by recent advection of seawater or it may to due to the presence of impermeable sediments in the center of the pond that limit seawater recirculation. This groundwater flux estimated from the radon and salinity data is comparable to a value of 3200-4500 m3 d-1 predicted by a recent hydrologic model (Masterson, 2004; Colman and Masterson, 20041). Additional work is needed to determine if the measured rate of discharge is representative of the long-term average, and to determine the rate of groundwater discharge seaward of Salt Pond. Data also suggest a TDN flux from groundwater to Salt Pond of ???2.6 mmol m-2 d-1, a figure comparable to fluxes observed in other eutrophic settings.

  6. Imaging the water column using sediment echosounder, ADCP and multibeam echosounder - new possibilities for sedimentological, biological and oceanographic studies

    NASA Astrophysics Data System (ADS)

    Preu, B.; Spiess, V.; Schwenk, T.; Haberkern, J.; Bergmann, F.; Max, L.; Iversen, M.; Fischer, G.; Hanebuth, T.; Krastel, S.; Hernández-Molina, F.; Schneider, R. R.

    2011-12-01

    Detection and characterization of nepheloid layers, which are often bound to water mass interfaces, and benthic boundary layers are today mostly restricted to sampling and optical measurements allowing quantification of particles at one single location. However, spatial analysis of the lateral variability of suspension clouds would offer remarkable new insight into the dynamics of large scale marine sediment dispersal systems. The understanding of along-slope and down-slope sedimentary processes and their deposits could be significantly improved by mapping of particle layers. Additionally, mapping of particle clouds in time and space would allow inferring on plankton concentrations and their migration in the water column, which would improve the understanding of the biological pump. Whereas spatial measurements using sampling and optical methods are time intensive and therefore, hard to accomplish, new developments in hull-mounted high-resolution hydro-acoustic instruments allow to store and process acoustic data, imaging the water column and thereby offer an easy and time saving alternative. We will present preliminary results of an integrated acoustic approach to image and analyze nepheloid layers and comparable particle clouds. We collected multiple hydro-acoustic data sets including 18 kHz echosounder (PARASOUND) and both 38 and 75 kHz ADCP (RD INSTRUMENTS) data in current controlled and high accumulating sedimentary regimes. Additionally, multibeam echosounder measurements including water column imaging were carried out using the new EM 122 (KONGSBERG). First, we present data off SE-Africa linking the oceanographic and sedimentological framework, in particular the impact of a lee eddy in the source region of the Agulhas Current on contouritic deposits. Secondly, data collected off Mauritania are used to determine the sensitivity of 18, 38 and 75 kHz to particle sizes in relation to optical estimated concentrations. Further, the vertical plankton migration is

  7. Lung surgery - discharge

    MedlinePlus

    Thoracotomy - discharge; Lung tissue removal - discharge; Pneumonectomy - discharge; Lobectomy - discharge; Lung biopsy - discharge; Thoracoscopy - discharge; Video-assisted thoracoscopic surgery - discharge; VATS - discharge; Thoracoscopy - discharge

  8. Improved error estimates of a discharge algorithm for remotely sensed river measurements: Test cases on Sacramento and Garonne Rivers

    NASA Astrophysics Data System (ADS)

    Yoon, Yeosang; Garambois, Pierre-André; Paiva, Rodrigo C. D.; Durand, Michael; Roux, Hélène; Beighley, Edward

    2016-01-01

    We present an improvement to a previously presented algorithm that used a Bayesian Markov Chain Monte Carlo method for estimating river discharge from remotely sensed observations of river height, width, and slope. We also present an error budget for discharge calculations from the algorithm. The algorithm may be utilized by the upcoming Surface Water and Ocean Topography (SWOT) mission. We present a detailed evaluation of the method using synthetic SWOT-like observations (i.e., SWOT and AirSWOT, an airborne version of SWOT). The algorithm is evaluated using simulated AirSWOT observations over the Sacramento and Garonne Rivers that have differing hydraulic characteristics. The algorithm is also explored using SWOT observations over the Sacramento River. SWOT and AirSWOT height, width, and slope observations are simulated by corrupting the "true" hydraulic modeling results with instrument error. Algorithm discharge root mean square error (RMSE) was 9% for the Sacramento River and 15% for the Garonne River for the AirSWOT case using expected observation error. The discharge uncertainty calculated from Manning's equation was 16.2% and 17.1%, respectively. For the SWOT scenario, the RMSE and uncertainty of the discharge estimate for the Sacramento River were 15% and 16.2%, respectively. A method based on the Kalman filter to correct errors of discharge estimates was shown to improve algorithm performance. From the error budget, the primary source of uncertainty was the a priori uncertainty of bathymetry and roughness parameters. Sensitivity to measurement errors was found to be a function of river characteristics. For example, Steeper Garonne River is less sensitive to slope errors than the flatter Sacramento River.

  9. Measurements of Secondary Electron Emission Effects in the Hall Thruster Discharge

    SciTech Connect

    Raitses, Y.; Smirnov, A.; Staack, D.; Fisch, N.J.

    2005-12-01

    The dependence of the maximum electron temperature on the discharge voltage is studied for two Hall thruster configurations, in which a collisionless plasma is bounded by channel walls made of materials with different secondary electron emission (SEE) properties. The linear growth of the temperature with the discharge voltage, observed in the channel with a low SEE yield, suggests that SEE is responsible for the electron temperature saturation in the thruster configuration with the channel walls having a higher SEE yield. The fact that the values of the electron temperature at saturation are rather high may indirectly support the recently predicted kinetic regime of the space charge saturation of the near-wall sheath in the thruster discharge. A correlation between the effects of the channel wall material on the electron temperature and the electron cross-field current was also observed.

  10. Measurements of secondary electron emission effects in the Hall thruster discharge

    SciTech Connect

    Raitses, Y.; Smirnov, A.; Staack, D.; Fisch, N.J.

    2006-01-15

    The dependence of the maximum electron temperature on the discharge voltage is studied for two Hall thruster configurations, in which a collisionless plasma is bounded by channel walls made of materials with different secondary electron emission (SEE) properties. The linear growth of the temperature with the discharge voltage, observed in the channel with a low SEE yield, suggests that SEE is responsible for the electron temperature saturation in the thruster configuration with the channel walls having a higher SEE yield. The fact that the values of the electron temperature at saturation are rather high may indirectly support the recently predicted kinetic regime of the space charge saturation of the near-wall sheath in the thruster discharge. A correlation between the effects of the channel wall material on the electron temperature and the electron cross-field current was also observed.

  11. Measurement of effective blast energy for direct initiation of spherical gaseous detonations from high-voltage spark discharge

    NASA Astrophysics Data System (ADS)

    Zhang, B.; Ng, H. D.; Lee, J. H. S.

    2012-01-01

    In this study, effective energy from spark discharge for direct blast initiation of spherical gaseous detonations is investigated. In the experiment, direct initiation of detonation is achieved via a spark discharge from a high-voltage and low-inductance capacitor bank and the spark energy is estimated from the analysis of the current output. To determine the blast wave energy from the powerful spark, the time-of-arrival of the blast wave in air is measured at different radii using a piezoelectric pressure transducer. Good agreement is found in the scaled blast trajectories, i.e., scaled time c o· t/ R o where c o is the ambient sound speed, as a function of blast radius R s/ R o between the numerical simulation of a spherical blast wave from a point energy source and the experimental results where the explosion length scale R o is computed using the equivalent spark energy from the first 1/4 current discharge cycle. Alternatively, by fitting the experimental trajectories data, the blast energy estimated from the numerical simulation appears also in good agreement with that obtained experimentally using the 1/4 cycle criterion. Using the 1/4 cycle of spark discharge for the effective energy, direct initiation experiments of spherical gaseous detonations are carried out to determine the critical initiation energy in C2H2-2.5O2 mixtures with 70 and 0% argon dilution. The experimental results obtained from the 1/4 cycle of spark discharge agree well with the prediction from two initiation models, namely, the Lee's surface energy model and a simplified work done model. The main source of discrepancy in the comparison can be explained by the uncertainty of cell size measurement which is needed for both the semi-empirical models.

  12. Relationships between dissolved organic matter and discharge: New insights from in-situ measurements in a northern forested watershed

    NASA Astrophysics Data System (ADS)

    Pellerin, B. A.; Shanley, J. B.; Saraceno, J.; Aiken, G.; Sebestyen, S. D.; Bergamaschi, B. A.

    2012-12-01

    Quantifying the fundamental linkages between hydrology and dissolved organic matter (DOM) dynamics in streams and rivers is critical for understanding carbon loads, ecosystem food webs and metal transport. Accurately assessing this relationship is difficult, however, given that rapid changes in water flow paths and associated DOM sources are often not captured by traditional discrete sampling intervals of weeks to months. We explored DOM - discharge relationships at Sleepers River below a 40.5 hectare USGS research watershed in northern Vermont by making 30 minute chromophoric DOM fluorescence (FDOM) measurements in-situ since October 2008 along with periodic discrete sampling for dissolved organic carbon. There is a tight coupling between the timing of increases in FDOM and discharge at Sleepers during events, but the ratio of FDOM to discharge exhibited considerable variability across seasons and events, as did FDOM-discharge hysteresis (FDOM variously peaked 1-4 hours after streamflow). Discrete DOM quality indicators (spectral slope, fluorescence index, SUVA) indicate DOM was predominantly terrestrial at all but the lowest flows, highlighting the important role of DOM-rich terrestrial flow paths as the primary source of stream DOM. Our results suggest that changes in flow paths are likely to be the primary drivers of future changes in DOM transport from this site rather than changes in DOM quality. Overcoming significant challenges inherent in continuous sensor deployments in watersheds (e.g. ice cover, suspended particles, remote communication and power) will allow for new insights into watershed biogeochemistry.

  13. Time and space-correlated plasma potential measurements in the near field of a coaxial Hall plasma discharge

    NASA Astrophysics Data System (ADS)

    Smith, A. W.; Cappelli, M. A.

    2009-07-01

    Space- and time-correlated measurements of floating and plasma potential are made in the near field, external flow cathode region of a coaxial Hall plasma discharge using an emissive probe synchronized to quasicoherent fluctuations in discharge current. The luminous axial feature frequently observed in the near field of operating plasma accelerators is found to be concomitant with a spike in the plasma potential (and electron temperature). The structure of the plasma potential allows for multiple avenues for back-streaming ions to accelerate toward the discharge front pole and may pull some classes of ions toward the central axis. The fluctuations in plasma properties exhibit a complex structure at frequencies on the order of the so-called "breathing mode" ionization instability often seen in these types of discharges. Most notably, the plasma potential appears to fluctuate in a helical fashion, resembling tilted drift waves rotating about the central axis. A simple analysis of these waves draws attention to the possible role that they may play in driving anomalous cross-field electron transport in the near field region.

  14. Measurement of Temporally and Spatially Resolved Electron Density in the Filament of a Pulsed Spark Discharge in Water

    NASA Astrophysics Data System (ADS)

    Niu, Zhiwen; Wen, Xiaoqiong; Ren, Chunsheng; Qiu, Yuliang

    2016-08-01

    The temporally and spatially resolved optical emission spectrum of Hα of a pulsed spark discharge in water was experimentally measured. The temporally and spatially resolved electron densities, along the radial direction of the spark filament, for a pulsed spark discharge in water with a conductivity of 100 μS/cm were investigated. The electron density in the spark filament was found to be in the 1018/cm3 order of magnitude. The highest electron density was measured at the primary stage of the spark filament, and it decreased with time. The radial distribution of electron density increased from the center to the edge of the spark filament. supported in part by National Natural Science Foundation of China (Nos. 11275040 and 51437002)

  15. Identification of errors in the electron density measurements of a tangential interferometer/polarimeter system during a tokamak discharge

    SciTech Connect

    Arakawa, H.; Kawano, Y.; Itami, K.

    2012-10-15

    A new method for the comparative verification of electron density measurements obtained with a tangential interferometer and a polarimeter during a discharge is proposed. The possible errors associated with the interferometer and polarimeter are classified by the time required for their identification. Based on the characteristics of the errors, the fringe shift error of the interferometer and the low-frequency noise of the polarimeter were identified and corrected for the JT-60U tangential interferometer/polarimeter system.

  16. Coupled surface-subsurface hydrologic measurements reveal infiltration, recharge, and discharge dynamics across the swash zone of a sandy beach

    NASA Astrophysics Data System (ADS)

    Heiss, James W.; Puleo, Jack A.; Ullman, William J.; Michael, Holly A.

    2015-11-01

    Swash-groundwater interactions affect the biogeochemistry of beach aquifers and the transport of solutes and sediment across the beachface. Improved understanding of the complex, coupled dynamics of surface and subsurface flow processes in the swash zone is required to better estimate chemical fluxes to the sea and predict the morphological evolution of beaches. Simultaneous high-frequency measurements of saturation, water table elevation, and the cross-shore locations of runup and the boundary between the saturated and unsaturated beachface (surface saturation boundary) were collected on a sandy beach to link groundwater flow dynamics with swash zone forcing. Saturation and lysimeter measurements showed the dynamic response of subsurface saturation to swash events and permitted estimation of infiltration rates. Surface and subsurface observations revealed a decoupling of the surface saturation boundary and the intersection between the water table and the beachface. Surface measurements alone were insufficient to delineate the infiltration and discharge zones, which moved independently of the surface saturation boundary. Results show for the first time the motion and areal extent of infiltration and recharge zones, and constrain the maximum size of the subaerial discharge zone over swash and tidal time scales. The width of the infiltration zone was controlled by swash processes, and subaerial discharge was controlled primarily by tidal processes. These dynamics reveal the tightly coupled nature of surface and subsurface processes over multiple time scales, with implications for sediment transport and fluid and solute fluxes through the hydrologically and biogeochemically active intertidal zone of sandy beaches.

  17. Correcting acoustic Doppler current profiler discharge measurement bias from moving-bed conditions without global positioning during the 2004 Glen Canyon Dam controlled flood on the Colorado River

    USGS Publications Warehouse

    Gartner, J.W.; Ganju, N.K.

    2007-01-01

    Discharge measurements were made by acoustic Doppler current profiler at two locations on the Colorado River during the 2004 controlled flood from Glen Canyon Dam, Arizona. Measurement hardware and software have constantly improved from the 1980s such that discharge measurements by acoustic profiling instruments are now routinely made over a wide range of hydrologic conditions. However, measurements made with instruments deployed from moving boats require reliable boat velocity data for accurate measurements of discharge. This is normally accomplished by using special acoustic bottom track pings that sense instrument motion over bottom. While this method is suitable for most conditions, high current flows that produce downstream bed sediment movement create a condition known as moving bed that will bias velocities and discharge to lower than actual values. When this situation exists, one solution is to determine boat velocity with satellite positioning information. Another solution is to use a lower frequency instrument. Discharge measurements made during the 2004 Glen Canyon controlled flood were subject to moving-bed conditions and frequent loss of bottom track. Due to site conditions and equipment availability, the measurements were conducted without benefit of external positioning information or lower frequency instruments. This paper documents and evaluates several techniques used to correct the resulting underestimated discharge measurements. One technique produces discharge values in good agreement with estimates from numerical model and measured hydrographs during the flood. ?? 2007, by the American Society of Limnology and Oceanography, Inc.

  18. Estimates of ground-water discharge as determined from measurements of evapotranspiration, Ash Meadows area, Nye County, Nevada

    USGS Publications Warehouse

    Laczniak, R.J.; DeMeo, G.A.; Reiner, S.R.; Smith, Jody L.; Nylund, W.E.

    1999-01-01

    Ash Meadows is one of the major discharge areas within the regional Death Valley ground-water flow system of southern Nevada and adjacent California. Ground water discharging at Ash Meadows is replenished from inflow derived from an extensive recharge area that includes the eastern part of the Nevada Test Site (NTS). Currently, contaminants introduced into the subsurface by past nuclear testing at NTS are the subject of study by the U.S. Department of Energy's Environmental Restoration Program. The transport of any contaminant in contact with ground water is controlled in part by the rate and direction of ground-water flow, which itself depends on the location and quantity of ground water discharging from the flow system. To best evaluate any potential risk associated with these test-generated contaminants, studies were undertaken to accurately quantify discharge from areas downgradient from the NTS. This report presents results of a study to refine the estimate of ground-water discharge at Ash Meadows. The study estimates ground-water discharge from the Ash Meadows area through a rigorous quantification of evapotranspiration (ET). To accomplish this objective, the study identifies areas of ongoing ground-water ET, delineates unique areas of ET defined on the basis of similarities in vegetation and soil-moisture conditions, and computes ET rates for each of the delineated areas. A classification technique using spectral-reflectance characteristics determined from satellite images recorded in 1992 identified seven unique units representing areas of ground-water ET. The total area classified encompasses about 10,350 acres dominated primarily by lush desert vegetation. Each unique area, referred to as an ET unit, generally consists of one or more assemblages of local phreatophytes. The ET units identified range from sparse grasslands to open water. Annual ET rates are computed by energy-budget methods from micrometeorological measurements made at 10 sites within six

  19. Measurements of Electron Temperature and Density, in an AC Pulsed Oxygen Plasma Discharge

    NASA Astrophysics Data System (ADS)

    Yousif, Farook; Martinez, Horacio; Castillo, Fermin

    2007-06-01

    Emission and analytical spectroscopy was applied to investigate O2 plasma, which was generated by an AC discharge between 0.15 and 0.5 Torr pressure. For the diagnostic study, a double Langmuir probe was employed. The derivation of plasma parameters is based on a theoretical description of the double-probe current-voltage characterization in the Thick Sheath Limit (TSL) region [1]. Electron temperature of Te = 1.09 eV and an ion density of ni= 2.08 x 10^10 cm-3 were evaluated at 2 Torr. We present electron temperature and ion density as a function of the pressure at 3 different power discharge levels. Also we present emission spectroscopy in the wavelength range of 200-1100 nm as a function of the pressure. [1] J.D. Swift and J. R. Schwar, Electric Probes for Plasma Diagnostics (New York: Elsevier) 1971.

  20. Kidney stones - lithotripsy - discharge

    MedlinePlus

    Extracorporeal shock wave lithotripsy - discharge; Shock wave lithotripsy - discharge; Laser lithotripsy - discharge; Percutaneous lithotripsy - discharge; Endoscopic lithotripsy - discharge; ESWL - discharge

  1. Pancreatitis - discharge

    MedlinePlus

    Chronic pancreatitis - discharge; Pancreatitis - chronic - discharge; Pancreatic insufficiency - discharge; Acute pancreatitis - discharge ... You were in the hospital because you have pancreatitis. This is a swelling of the pancreas. You ...

  2. Simultaneous measurements of wire electrode surface contamination and corona discharge characteristics in an air-cleaning electrostatic precipitator

    SciTech Connect

    Kanazawa, Seiji; Ohkubo, Toshikazu; Nomoto, Yukiharu; Adachi, Takayoshi; Chang, J.S.

    1997-01-01

    Contamination of the corona wire in a wire-to-plate type air-cleaning electrostatic precipitator is studied experimentally. In order to enhance the contamination of wire, air containing dusts is directly supplied to a part of the wire electrode. Spores of Lycopodium and cigarette smoke particles are used as test dusts. Simultaneous measurements of wire electrode optical images and corona discharge modes are carried out during contamination processes. Results show that corona discharge modes and optical emission from the wire electrode change with time due to the surface contamination. In the case of cigarette smoke, after a time elapsed, streamer coronas appear due to the buildup of smoke particles on the wire surface. After the first streamer generation, the corona current fluctuates with time because the formation and diminution of the projections occur alternately at the different parts on the wire electrode surface.

  3. Concentration measurement of NO using self-absorption spectroscopy of the γ band system in a pulsed corona discharge.

    PubMed

    Zhai, Xiaodong; Ding, Yanjun; Peng, Zhimin; Luo, Rui

    2012-07-10

    Nitric oxide (NO) concentrations were measured using the γ band system spectrum based on the strong self-absorption effect of NO in pulsed corona discharges. The radiative transitional intensities of the NO γ band were simulated based on the theory of molecular spectroscopy. The intensities of some bands, especially γ(0,0) and γ(1,0), are weakened by the self-absorption. The correlations between the spectral self-absorption intensities and NO concentration were validated using a modified Beer-Lambert law with a combined factor K relating the branching ratio and the NO concentration, and a nonlinear index α that is applicable to the broadband system. Optical emissive spectra in pulsed corona discharges in NO and N2/He mixtures were used to evaluate the two parameters for various conditions. Good agreement between the experimental and theoretical results verifies the self-absorption behavior seen in the UV spectra of the NO γ bands. PMID:22781235

  4. Time and wavelength resolved measurements of the VUV excimer emission generated in a windowless dielectric barrier discharge (DBD) in argon

    NASA Astrophysics Data System (ADS)

    Ganesan, Rajesh; Kane, Deborah; Carman, Robert

    2011-10-01

    Temporal analysis of the VUV emission from a windowless dielectric barrier discharge in pure argon from 50-800 mbar were carried out to gain insight into the underlying kinetic processes relating to the first and second continuum emission bands of the Ar2* excimer. Pulsed excitation using bi-polar voltage pulses with 2% duty-cycle and 32kHz repetition frequency were employed to achieve a uniform discharge with well-controlled electrical breakdown characteristics. By comprehensively measuring the rising and decay time constants for ~50 individual wavelengths within the first and second continuum of argon covering the range λ = 107nm-140nm, the dominant collisional and radiative rates relating to Ar2* excimer production and loss have been obtained. The variation of time constants as a function of wavelength and gas pressure has been determined. The VUV emission curves at the transition phase between the first and second continuum have been analyzed in detail.

  5. Uniform and non-uniform modes of nanosecond-pulsed dielectric barrier discharge in atmospheric air: fast imaging and spectroscopic measurements of electric field

    PubMed Central

    Liu, Chong; Dobrynin, Danil; Fridman, Alexander

    2014-01-01

    In this study, we report experimental results on fast ICCD imaging of development of nanosecond-pulsed dielectric barrier discharge (DBD) in atmospheric air and spectroscopic measurements of electric field in the discharge. Uniformity of the discharge images obtained with nanosecond exposure times were analyzed using chi-square test. The results indicate that DBD uniformity strongly depends on applied (global) electric field in the discharge gap, and is a threshold phenomenon. We show that in the case of strong overvoltage on the discharge gap (provided by fast rise times), there is transition from filamentary to uniform DBD mode which correlates to the corresponding decrease of maximum local electric field in the discharge. PMID:25071294

  6. Modelling depth-averaged flow in the fluvial-tidal zone: the spatio-temporal interaction of river discharge and tidal cycle

    NASA Astrophysics Data System (ADS)

    Sandbach, S. D.; Nicholas, A.; Ashworth, P. J.; Best, J. L.; Parsons, D. R.; Sambrook Smith, G.; Simpson, C.; Keevil, C.

    2012-12-01

    The Columbia River has a strong seasonal variation in discharge, with a discharge around 3000 m3/s during the fall-early spring increasing to 12000 m3/s during the spring freshet. In this paper, we present flow predictions obtained using a 2D depth-averaged model (Delft3D) and flow measurements obtained using an Acoustic Doppler Current Profiler (ADCP). The 80 km-long and 3-5 km-wide modelled reach of the Columbia River Estuary (USA) extends from an upriver boundary at the Beaver Army Terminal (BAT) to the downstream water level boundary at the Hammond Tide Gauge (HTG) in the lower part of the estuary. The simulations were conducted using a boundary-fitted mesh with 120,000 ~40 m grid cells. Gauged discharge at BAT and water levels at HTG provide boundary conditions for the model. The bed topography was derived from a series of bathymetric (multi- and single-beam echo soundings) and LiDAR surveys conducted during 2009 and 2010 by NOAA, USACE and LCREP, and collated to generate a Digital Elevation Model (DEM). Bed shear stress was estimated using a variety of roughness parameterisation methods including Chezy, Colebrook-White and Manning and a uniform eddy-viscosity turbulence closure. The ADCP data were collected during low river flow in October 2011 (~4000 m3/s) and high river flow in June 2011 (~14000 m3/s) and June 2012 (~12000 m3/s). ADCP data were collected from six transects located within the fluvial-tidal zone for each data collection period. The width of these transects ranged from 0.5-2 km and the data were collected during both flood and ebb. The model was calibrated using water level measurements within the modelled reach and these results compare well with the measured ADCP data. Both field data and model results reveal the importance of the balance between the hydrodynamic forcing of the tidal flood and river flow, combined with the resultant interaction with bar topography and bed roughness. These complex interactions result in the flow reversals

  7. A passive measurement of dissociated atom densities in atmospheric pressure air discharge plasmas using vacuum ultraviolet self-absorption spectroscopy

    SciTech Connect

    Laity, George; Fierro, Andrew; Dickens, James; Neuber, Andreas; Frank, Klaus

    2014-03-28

    We demonstrate a method for determining the dissociation degree of atmospheric pressure air discharges by measuring the self-absorption characteristics of vacuum ultraviolet radiation from O and N atoms in the plasma. The atom densities are determined by modeling the amount of radiation trapping present in the discharge, without the use of typical optical absorption diagnostic techniques which require external sources of probing radiation into the experiment. For an 8.0 mm spark discharge between needle electrodes at atmospheric pressure, typical peak O atom densities of 8.5 × 10{sup 17} cm{sup −3} and peak N atom densities of 9.9 × 10{sup 17} cm{sup −3} are observed within the first ∼1.0 mm of plasma near the anode tip by analyzing the OI and NI transitions in the 130.0–132.0 nm band of the vacuum ultraviolet spectrum.

  8. Stream measurements locate thermogenic methane fluxes in groundwater discharge in an area of shale-gas development.

    PubMed

    Heilweil, Victor M; Grieve, Paul L; Hynek, Scott A; Brantley, Susan L; Solomon, D Kip; Risser, Dennis W

    2015-04-01

    The environmental impacts of shale-gas development on water resources, including methane migration to shallow groundwater, have been difficult to assess. Monitoring around gas wells is generally limited to domestic water-supply wells, which often are not situated along predominant groundwater flow paths. A new concept is tested here: combining stream hydrocarbon and noble-gas measurements with reach mass-balance modeling to estimate thermogenic methane concentrations and fluxes in groundwater discharging to streams and to constrain methane sources. In the Marcellus Formation shale-gas play of northern Pennsylvania (U.S.A.), we sampled methane in 15 streams as a reconnaissance tool to locate methane-laden groundwater discharge: concentrations up to 69 μg L(-1) were observed, with four streams ≥ 5 μg L(-1). Geochemical analyses of water from one stream with high methane (Sugar Run, Lycoming County) were consistent with Middle Devonian gases. After sampling was completed, we learned of a state regulator investigation of stray-gas migration from a nearby Marcellus Formation gas well. Modeling indicates a groundwater thermogenic methane flux of about 0.5 kg d(-1) discharging into Sugar Run, possibly from this fugitive gas source. Since flow paths often coalesce into gaining streams, stream methane monitoring provides the first watershed-scale method to assess groundwater contamination from shale-gas development. PMID:25786038

  9. Ion distribution measurements to probe target and plasma processes in electronegative magnetron discharges. I. Negative ions

    SciTech Connect

    Welzel, Th.; Ellmer, K.; Naumov, S.

    2011-04-01

    Mass and energy spectra of negative ions in magnetron sputtering discharges have been investigated with an energy-dispersive mass spectrometer. The dc magnetrons have been operated in the same reactive Ar/O{sub 2} atmosphere but with three different target materials: Cu, In, and W. Besides negative ions of the working gas, a variety of target metal containing negative molecular ions were found in the discharge. Their occurrence is strongly dependent on the target material. It has been correlated to the electron affinity and the bond strength of the molecules which has been calculated by density functional theory. Energy spectra of the negative ions exhibit three contributions that are clearly distinguishable. Their different origin is discussed as electron attachment in the gas phase and at the target surface, and molecule fragmentation during transport from target to substrate. The latter two contributions again significantly deviate for different target material. The high-energy part of the spectra has been analyzed with respect to the energy the particles gain upon release from the surface. It suggests that bigger molecules formed on the surface are released by ion-assisted desorption.

  10. Pulsed-gas glow discharge for ultrahigh mass resolution measurements with Fourier transform ion cyclotron resonance mass spectrometry

    SciTech Connect

    Watson, C.H.; Eyler, J.R.; Barshick, C.M.; Wronka, J.; Laukien, F.H.

    1996-02-01

    A new pulsed-gas glow discharge (GD) source has been developed for use with an external ion source Fourier transform ion cyclotron resonance (FTICR) mass spectrometer. With pulsed argon gas introduction into the GD source, the gas load and pressure in the mass analyzer region were greatly reduced; this resulted in improved mass resolution. Mass resolution of greater than 145000 (fwhm) has been achieved for Cu{sup +} ions from a brass sample, the highest reported for any type of GD mass spectrometer. The pulsed-gas GD source promises analytical usefulness for ultrahigh resolution measurements in GD mass spectrometry. 16 refs., 3 figs.

  11. Discharge and water-depth estimates for ungauged rivers: Combining hydrologic, hydraulic, and inverse modeling with stage and water-area measurements from satellites

    NASA Astrophysics Data System (ADS)

    Liu, Ganming; Schwartz, Franklin W.; Tseng, Kuo-Hsin; Shum, C. K.

    2015-08-01

    Anticipating future global freshwater scarcity and providing mitigation require timely knowledge of spatiotemporal dynamics of discharge for gauged and, more challengingly, ungauged rivers. This study describes a coupled hydrologic (SWAT) and hydraulic (XSECT) modeling approach set in a genetic algorithm framework for estimating discharge and water depth for ungauged rivers from space. The method was tested in the Red River of the North basin by comparing simulated discharges and depths from 2006 to 2010 to in situ observations from across the basin. Results showed that calibration using only remotely sensed data (i.e., water levels from ENVISAT altimetry and water extents from LANDSAT) along the main stem of the Red River yielded daily and monthly estimates of river discharge, which correlated to measured discharges at three gaging stations on the main stem with R2 values averaging 0.822 and 0.924, respectively. The comparisons of modeled and measured discharges were also extended to smaller tributaries, yielding a mean R2 of 0.809 over seven gaging stations. The modeling approach also provided estimates of water depth that correlated to observations at four stations with an average R2 of 0.831. We conclude that the integrated modeling approach is able to estimate discharge and water depth from space for larger ungauged rivers. This study also implies that in situ discharge data may not be necessary for successful hydrologic model calibration.

  12. Measurements of 3D slip velocities and plasma column lengths of a gliding arc discharge

    SciTech Connect

    Zhu, Jiajian; Gao, Jinlong; Ehn, Andreas; Aldén, Marcus; Li, Zhongshan E-mail: alpers@ma.tum.de; Moseev, Dmitry; Kusano, Yukihiro; Salewski, Mirko; Alpers, Andreas E-mail: alpers@ma.tum.de; Gritzmann, Peter; Schwenk, Martin

    2015-01-26

    A non-thermal gliding arc discharge was generated at atmospheric pressure in an air flow. The dynamics of the plasma column and tracer particles were recorded using two synchronized high-speed cameras. Whereas the data analysis for such systems has previously been performed in 2D (analyzing the single camera image), we provide here a 3D data analysis that includes 3D reconstructions of the plasma column and 3D particle tracking velocimetry based on discrete tomography methods. The 3D analysis, in particular, the determination of the 3D slip velocity between the plasma column and the gas flow, gives more realistic insight into the convection cooling process. Additionally, with the determination of the 3D slip velocity and the 3D length of the plasma column, we give more accurate estimates for the drag force, the electric field strength, the power per unit length, and the radius of the conducting zone of the plasma column.

  13. Estimation of Photon Effects on Townsend Discharges for SecondaryElectronEmission Coefficient Measurements

    NASA Astrophysics Data System (ADS)

    Yoshinaga, Tomokazu; Akashi, Haruaki

    2015-09-01

    A Monte Carlo simulation (MCS) is applied to investigate the secondary electron emission in Argon Townsend discharges. The influxes of ions, photons and metastable species onto the cathode surface are estimated simply from the number of inelastic collisions. The effect of photons becomes significant especially under higher pd conditions since the photon influx increases. This suggests the possibility of the estimation of the secondary electron emission coefficient of photons by examining breakdown voltage characteristics (Paschen curves). The effect of metastable species is much smaller than those of ions and photons and is negligible. The Paschen curves evaluated with MCS agrees well with the results of one-dimensional fluid model simulation when the photon effect is neglected, showing the necessity of further improvement. Supported by JSPS KAKENHI Grant Number 26820108.

  14. Hairpin resonator probes with frequency domain boxcar operation for time resolved density measurements in pulsed RF discharges

    NASA Astrophysics Data System (ADS)

    Peterson, David; Kummerer, Theresa; Coumou, David; Shannon, Steven

    2014-10-01

    In this work, microsecond time resolved electron density measurements in pulsed RF discharges are shown using an automated hairpin resonance probe using relatively low cost electronics, on par with normal Langmuir probe boxcar mode operation. A low cost signal generator is used to produce the applied microwave frequency and the reflected waveform is filtered to remove the RF component. The signal is then heterodyned with a simple frequency mixer to produce a dc signal read by an oscilloscope to determine the electron density. The applied microwave frequency is automatically shifted in small increments in a frequency boxcar routine through a Labview™program to determine the resonant frequency. A simple dc sheath correction is then easily applied since the probe is fully floating, producing low cost, high fidelity, and highly reproducible electron density measurements. The measurements are made in a capacitively coupled, parallel plate configuration in a 13.56 MHz, 50--200 W RF discharge pulsed at 500 Hz, 200 W, 50% duty cycle. The gas input ranged from 50--100 mTorr pure Ar or with 5--10% O/He mixtures.

  15. Estimating Discharge using Multi-level Velocity Data from Acoustic Doppler Instruments

    NASA Astrophysics Data System (ADS)

    Bang Poulsen, J.; Rømer Rasmussen, K.; Bering Ovesen, N.

    2010-12-01

    been recorded at two depths since the water table drops below the uppermost sensor. A pressure transducer is also placed at the pole where it records the stage. The monthly control measurements made by the water authority office are made with an ADCP-instrument (Streampro, acoustic Doppler current profiler) which is pulled across the stream next to the in situ Doppler instruments. As part of the present project supplementary ADCP-data have been collected for different stage-values. For each stage many pull traverses (>20) have been combined in order to produce reliable high-density stream velocity profiles across the stream. Currently, the different sets of velocity data are being analyzed in order to investigate how well the discharge may be predicted from the in situ Dopplers. The poster will present the field-set up and the results of the data analysis.

  16. Calibration-free self-absorption model for measuring nitric oxide concentration in a pulsed corona discharge.

    PubMed

    Du, Yanjun; Ding, Yanjun; Liu, Yufeng; Lan, Lijuan; Peng, Zhimin

    2014-08-01

    The effect of self-absorption on emission intensity distributions can be used for species concentration measurements. A calculation model is developed based on the Beer-Lambert law to quantify this effect. And then, a calibration-free measurement method is proposed on the basis of this model by establishing the relationship between gas concentration and absorption strength. The effect of collision parameters and rotational temperature on the method is also discussed. The proposed method is verified by investigating the nitric oxide emission bands (A²Σ⁺→X²∏) that are generated by a pulsed corona discharge at various gas concentrations. Experiment results coincide well with the expectations, thus confirming the precision and accuracy of the proposed measurement method. PMID:25090323

  17. Lung surgery - discharge

    MedlinePlus

    Thoracotomy - discharge; Lung tissue removal - discharge; Pneumonectomy - discharge; Lobectomy - discharge; Lung biopsy - discharge; Thoracoscopy - discharge; Video-assisted thoracoscopic surgery - discharge; VATS - ...

  18. Hysterectomy - laparoscopic - discharge

    MedlinePlus

    Supracervical hysterectomy - discharge; Removal of the uterus - discharge; Laparoscopic hysterectomy - discharge; Total laparoscopic hysterectomy - discharge; TLH - discharge; Laparoscopic supracervical ...

  19. Shoulder replacement - discharge

    MedlinePlus

    Total shoulder arthroplasty - discharge; Endoprosthetic shoulder replacement - discharge; Partial shoulder replacement - discharge; Partial shoulder arthroplasty - discharge; Replacement - shoulder - discharge; ...

  20. Radical prostatectomy - discharge

    MedlinePlus

    ... prostatectomy - discharge; Laparoscopic radical prostatectomy - discharge; LRP - discharge; Robotic-assisted laparoscopic prostatectomy - discharge ; RALP - discharge; Pelvic lymphadenectomy - ...

  1. Ion distribution measurements to probe target and plasma processes in electronegative magnetron discharges. II. Positive ions

    SciTech Connect

    Welzel, Th.; Ellmer, K.; Naumov, S.

    2011-04-01

    Spectra of the ion mass and energy distributions of positive ions in reactive (Ar/O{sub 2}) and nonreactive (Ar) dc magnetron sputtering discharges have been investigated by energy-resolved mass spectrometry. The results of three sputter target materials, i.e., Cu, In, and W are compared to each other. Besides the main gas constituents, mass spectra reveal a variety of molecular ions which are dependent on the target material. In reactive mode, ArO{sup +} is always observed in Ar/O{sub 2} but molecules containing Ar and the metal were exclusively found for the Cu target. The occurrence of the different ions is explained in the context of their bond strengths obtained from density functional theory calculations. The energy spectra generally contain the known low-energy peak corresponding to the plasma potential. Differently extended high-energy tails due to sputtered material were observed for the different targets. Besides these, high-energetic ions were detected with up to several 100 eV. Their energies are significantly different for Ar{sup +} and O{sup +} with Ar{sup +} strongly depending on the target material. The spectra are discussed together with results from transport of ions in matter (TRIM) calculation to elucidate the origin of these energetic ions.

  2. Alternative method for estimating the cross-sectional interpolation errors of discharge measurements using the velocity-area method

    NASA Astrophysics Data System (ADS)

    Despax, Aurélien; Perret, Christian; Garçon, Rémy; Hauet, Alexandre; Belleville, Arnaud; Le Coz, Jérôme; Favre, Anne-Catherine

    2016-04-01

    Quantifying the quality of discharge measurements by uncertainty analysis is a challenge in the hydrometric community. Discharge measurements are the first step to produce hydrometric data which are used in many hydrological studies like design of hydraulic structures or calibration of hydrological models for flood forecasting and warning. Thus associated uncertainty has to be estimated carefully. The velocity-area method is a common approach for estimating river discharge. It consists in integrating depths and point velocities through the cross-section. Due to the limited number of point measurements, the quality of the measurement depends mainly on the sampling strategy. Different methods of uncertainty estimation are available in the literature (ISO 748, Q+ and IVE). The main uncertainty component, noted um, is often related to the cross-sectional interpolation errors. However the computation of this term according to these approaches does not evaluate both the sampling strategy and the complexity of the cross-section. The FLAURE method (FLow Analog UnceRtainty Estimation) includes a new methodology to estimate this term. It is based on the study of high-resolution stream-gaugings (i.e. reference stream-gaugings made with a high number of verticals). The high-resolution measurements are first subsampled by reducing the number of verticals to generate a sample of realistic stream-gaugings. A statistical analysis is performed to estimate the um component and then a sampling quality index is defined. For each reference stream-gauging, it leads to a curve of um component as a function of the sampling quality index. This set of curves is finally used to compute the um component of any routine stream-gauging. Curves are then selected according to the similitude between the routine stream-gauging and reference stream-gaugings. The similitude between the routine stream-gauging and reference stream-gaugings is evaluated thanks to the Nash criteria computed on lateral

  3. Application of HFCT and UHF Sensors in On-Line Partial Discharge Measurements for Insulation Diagnosis of High Voltage Equipment

    PubMed Central

    Álvarez, Fernando; Garnacho, Fernando; Ortego, Javier; Sánchez-Urán, Miguel Ángel

    2015-01-01

    Partial discharge (PD) measurements provide valuable information for assessing the condition of high voltage (HV) insulation systems, contributing to their quality assurance. Different PD measuring techniques have been developed in the last years specially designed to perform on-line measurements. Non-conventional PD methods operating in high frequency bands are usually used when this type of tests are carried out. In PD measurements the signal acquisition, the subsequent signal processing and the capability to obtain an accurate diagnosis are conditioned by the selection of a suitable detection technique and by the implementation of effective signal processing tools. This paper proposes an optimized electromagnetic detection method based on the combined use of wideband PD sensors for measurements performed in the HF and UHF frequency ranges, together with the implementation of powerful processing tools. The effectiveness of the measuring techniques proposed is demonstrated through an example, where several PD sources are measured simultaneously in a HV installation consisting of a cable system connected by a plug-in terminal to a gas insulated substation (GIS) compartment. PMID:25815452

  4. Application of HFCT and UHF sensors in on-line partial discharge measurements for insulation diagnosis of high voltage equipment.

    PubMed

    Álvarez, Fernando; Garnacho, Fernando; Ortego, Javier; Sánchez-Urán, Miguel Ángel

    2015-01-01

    Partial discharge (PD) measurements provide valuable information for assessing the condition of high voltage (HV) insulation systems, contributing to their quality assurance. Different PD measuring techniques have been developed in the last years specially designed to perform on-line measurements. Non-conventional PD methods operating in high frequency bands are usually used when this type of tests are carried out. In PD measurements the signal acquisition, the subsequent signal processing and the capability to obtain an accurate diagnosis are conditioned by the selection of a suitable detection technique and by the implementation of effective signal processing tools. This paper proposes an optimized electromagnetic detection method based on the combined use of wideband PD sensors for measurements performed in the HF and UHF frequency ranges, together with the implementation of powerful processing tools. The effectiveness of the measuring techniques proposed is demonstrated through an example, where several PD sources are measured simultaneously in a HV installation consisting of a cable system connected by a plug-in terminal to a gas insulated substation (GIS) compartment. PMID:25815452

  5. Comparison between Langmuir probe and microwave autointerferometry measurements at intermediate pressure in an argon surface wave discharge

    SciTech Connect

    Rousseau, A.; Teboul, E.; Bechu, S.

    2005-10-15

    This paper is devoted to the validation of Langmuir probe technique by microwave autointerferometry in a surface wave discharge at medium pressure (from 0.1 up to 10 Torr). Temperatures of neutrals, obtained from Rayleigh scattering, and electrons, given by double probe measurements, have been used to estimate the mean free path and the sheath length. Hence, the number of collisions in the sheath has been obtained. We have verified that two different phenomena occur in the sheath, while the pressure increases. These phenomena are depicted, in literature, as two different coefficients used to modify the value of the noncollisional current of Laframboise. Coefficients given by various authors have been investigated with accuracy knowing the number of collisions in the sheath. Very good agreements are obtained between Zakrzewski and Kopiczynski theory and autointerferometry measurements which are unaffected by collisional phenomena.

  6. The measurement of electron number density in helium micro hollow gas discharge using asymmetric He I lines

    NASA Astrophysics Data System (ADS)

    Jovović, J.; Šišović, N. M.

    2015-09-01

    The electron number density N e in helium micro hollow gas discharge (MHGD) is measured by means of optical emission spectroscopy (OES) techniques. The structure of MHGD is a gold-alumina-gold sandwich with 250 μm alumina thickness and 100 μm diameter hole. The electron temperature T e and gas temperature T g in the discharge is determined using the relative intensity of He I lines and {{\\text{N}}2}+≤ft({{\\text{B}}2}Σ\\text{u}+- {{X}2}Σ\\text{g}+\\right) R branch lines in the frame of BP technique, respectively. The simple procedure based on spectral line broadening theory was developed in MATLAB to generate synthetic neutral line asymmetric profiles. The synthetic profiles were compared with an experimental He I 447.1 nm and He I 492.2 nm line to obtain N e from the centre of a micro hollow gas discharge (MHGD) source in helium. The N e results were compared with N e values obtained from the forbidden-to-allowed (F/A) intensity ratio technique. The comparison confirmed higher N e determined using a F/A ratio due to large uncertainty of the method. Applying the fitting formula for a He I 492.2 nm line derived from computer simulation (CS) gives the same N e values as the one determined using the MATLAB procedure in this study. The dependence of N e on gas pressure and electric current is investigated as well.

  7. A Bayesian algorithm for estimation of river depth, roughness and discharge from SWOT measurements of height and inundated area

    NASA Astrophysics Data System (ADS)

    Durand, M. T.; Andreadis, K.; Smith, L. C.; Alsdorf, D. E.; Mersel, M. K.

    2011-12-01

    The Surface Water and Ocean Topography (SWOT) satellite is a swath-mapping radar interferometer that will provide water elevations over inland water bodies and over the ocean. SWOT represents a fundamentally new approach to characterizing fluvial processes, especially river discharge. However, because SWOT will observe water surface elevations, but not river bathymetric elevations, the cross-sectional flow area will only be observed above the lowest observed river depth. The so-called SWOT hydrology "virtual mission" (VM) has explored several approaches to depth estimation. Simplistic treatment of river depth spatial variability has been a key limitation of most existing VM work; put simply, geomorphology matters. The challenge for SWOT is how to perform the inverse problem of characterizing bathymetry and river flow given SWOT water surface elevation (WSE) measurements. This task falls at the intersection of two disciplines, engineering open channel hydraulics and fluvial geomorphology. In hydraulic formulations the physical form of the channel combined with conservation of mass and momentum dictate a complex spatiotemporal response of WSE to spatial changes in river bathymetry (i.e. changes in bed slope and cross-section) and temporal changes of flow propagating downstream. By combining prior information on river conditions and fluvial geomorphology with SWOT observations, it is essentially possible to do hydraulic modeling backwards, estimating river discharge, bathymetry, and roughness. Here, we present synthetic SWOT observations of water elevations over the Ohio River based on a dynamic simulation of approximately six months. Second, we present a simple Bayesian approach to simultaneously estimate river bathymetry, roughness and discharge. Prior estimates of bathymetry and roughness are generated based on a simple depth estimate, multiplied by random errors with an exponential autocorrelation function. We then implement a Monte Carlo Markov Chain algorithm to

  8. A prototype of radar-drone system for measuring the surface flow velocity at river sites and discharge estimation

    NASA Astrophysics Data System (ADS)

    Moramarco, Tommaso; Alimenti, Federico; Zucco, Graziano; Barbetta, Silvia; Tarpanelli, Angelica; Brocca, Luca; Mezzanotte, Paolo; Rosselli, Luca; Orecchini, Giulia; Virili, Marco; Valigi, Paolo; Ciarfuglia, Thomas; Pagnottelli, Stefano

    2015-04-01

    Discharge estimation at a river site depends on local hydraulic conditions identified by recording water levels. In fact, stage monitoring is straightforward and relatively inexpensive compared with the cost necessary to carry out flow velocity measurements which are, however, limited to low flows and constrained by the accessibility of the site. In this context the mean flow velocity is hard to estimate for high flow, affecting de-facto the reliability of discharge assessment for extreme events. On the other hand, the surface flow velocity can be easily monitored by using radar sensors allowing to achieve a good estimate of discharge by exploiting the entropy theory applied to rivers hydraulic (Chiu,1987). Recently, a growing interest towards the use of Unmanned Aerial Vehicle (UVA), henceforth drone, for topographic applications is observed and considering their capability drones may be of a considerable interest for the hydrological monitoring and in particular for streamflow measurements. With this aim, for the first time, a miniaturized Doppler radar sensor, operating at 24 GHz, will be mounted on a drone to measure the surface flow velocity in rivers. The sensor is constituted by a single-board circuit (i.e. is a fully planar circuits - no waveguides) with the antenna on one side and the front-end electronic on the other side (Alimenti et al., 2007). The antenna has a half-power beam width of less than 10 degrees in the elevation plane and a gain of 13 dBi. The radar is equipped with a monolithic oscillator and transmits a power of about 4 mW at 24 GHz. The sensor is mounted with an inclination of 45 degrees with respect to the drone flying plane and such an angle is considered in recovering the surface speed of the water. The drone is a quadricopter that has more than 30 min, flying time before recharging the battery. Furthermore its flying plan can be scheduled with a suitable software and is executed thanks to the on-board sensors (GPS, accelerometers

  9. Measurement of plasma density in the discharge maintained in a nonuniform gas flow by a high-power terahertz-wave gyrotron

    NASA Astrophysics Data System (ADS)

    Sidorov, A. V.; Razin, S. V.; Golubev, S. V.; Safronova, M. I.; Fokin, A. P.; Luchinin, A. G.; Vodopyanov, A. V.; Glyavin, M. Yu.

    2016-04-01

    We performed measurements of plasma density in a "point-like" discharge, which is generated in a nonuniform flow of a gas (argon) under the action of high-power terahertz gyrotron radiation with a frequency of 0.67 THz, a power of 40 kW, and a pulse duration of 20 μs. The nonuniform flow was produced by injecting the gas to the vacuum chamber through a small hole (0.14 mm in diameter) under a background pressure at a level of 0.01 Torr. The discharge developed and was localized only in a small region of space (about 1 mm) near the gas injection hole, where the pressure was high (close to the atmospheric one) and the breakdown conditions (the "point-like" discharge) were fulfilled. The density of electrons in the discharge was measured by observing the Stark broadening of the atomic radiation line Hα of hydrogen (656.3 nm) which was present in the discharge as a minor admixture. The plasma density in the discharge was equal to about 2 × 1016 cm-3, which exceeds the cut-off density for a frequency of 0.67 THz used to maintain the discharge.

  10. Spatially and Temporally Resolved Atomic Oxygen Measurements in Short Pulse Discharges by Two Photon Laser Induced Fluorescence

    NASA Astrophysics Data System (ADS)

    Lempert, Walter; Uddi, Mruthunjaya; Mintusov, Eugene; Jiang, Naibo; Adamovich, Igor

    2007-10-01

    Two Photon Laser Induced Fluorescence (TALIF) is used to measure time-dependent absolute oxygen atom concentrations in O2/He, O2/N2, and CH4/air plasmas produced with a 20 nanosecond duration, 20 kV pulsed discharge at 10 Hz repetition rate. Xenon calibrated spectra show that a single discharge pulse creates initial oxygen dissociation fraction of ˜0.0005 for air like mixtures at 40-60 torr total pressure. Peak O atom concentration is a factor of approximately two lower in fuel lean (φ=0.5) methane/air mixtures. In helium buffer, the initially formed atomic oxygen decays monotonically, with decay time consistent with formation of ozone. In all nitrogen containing mixtures, atomic oxygen concentrations are found to initially increase, for time scales on the order of 10-100 microseconds, due presumably to additional O2 dissociation caused by collisions with electronically excited nitrogen. Further evidence of the role of metastable N2 is demonstrated from time-dependent N2 2^nd Positive and NO Gamma band emission spectroscopy. Comparisons with modeling predictions show qualitative, but not quantitative, agreement with the experimental data.

  11. Simultaneous measurements of NO/x/, NO, and O3 production in a laboratory discharge - Atmospheric implications

    NASA Technical Reports Server (NTRS)

    Levine, J. S.; Rogowski, R. S.; Gregory, G. L.; Howell, W. E.; Fishman, J.

    1981-01-01

    Simultaneous measurements of NO(x) (NO + NO2), NO, and O3 production in a laboratory discharge show that within the uncertainties of the experiment, all of the NO(x) produced was NO, and no detectable enhancement of O3 after the discharge was observed. The laboratory experiments described gave an NO production rate of 5 + or - 2 x 10 to the 16th molecules/joule mole for a 100,000-1,000,000 joules/m spark. Assuming that the global dissipation of lightning energy is about 10 to the -8th joules/sq cm per sec (Dawson, 1980; and Hill et al., 1980), the NO production rate results in a global source of NO due to lightning of about 1.8 Mt(N)/yr, which is considerably lower than earlier estimates. This lower value for NO(x) production by lightning suggests that NO(x) emissions from anthropogenic sources, estimated to be at least 20 MT(N)/yr, may be the dominant source of NO(x) to the global troposphere. Furthermore, since most of the anthropogenic sources of NO(x) are located in the Northern Hemisphere, this new interpretation of the relative source strengths of this species favors a highly skewed asymmetric distribution of NO(x).

  12. Measuring the Thermal Conductivity of Sediments for the Estimation of Groundwater Discharge to Surface Waters with Temperature Probes

    NASA Astrophysics Data System (ADS)

    Duque, C.; Müller, S.; Sebok, E.; Engesgaard, P. K.

    2015-12-01

    Using temperature probes is a common exploratory method for studying groundwater-surface water interaction due to the ease for collecting measurements and the simplicity of the different analytical solutions. This approach requires to define the surface water temperature, the groundwater temperature and a set of parameters (density and specific capacity of water, and thermal conductivity of sediments) that can be easily extracted from tabulated values under the assumption that they are homogeneous in the study area. In the case of the thermal conductivity, it is common to apply a standard value of 1.84 Wm-1 C-1 corresponding to sand. Nevertheless the environments where this method is applied, like streambeds or lake/lagoons shores, are sedimentary depositional systems with high energy and biological activity that often lead to sediments dominated by organic matter or sharp changes in grain size modifying greatly the thermal conductivity values. In this study, the thermal conductivity was measured in situ along transects where vertical temperature profiles were collected in a coastal lagoon bed receiving groundwater discharge (Ringkøbing Fjord, Denmark). A set of 4 transects with 10-20 temperature profiles during 3 different seasons was analyzed together with more than 150 thermal conductivity measurements along the working transects and in experimental parcels of 1 m2 where the cm scale spatial variability of the thermal conductivity was assessed. The application of a literature-based bulk thermal conductivity of 1.84 Wm-1 C-1 instead of field data that ranged from 0.62 to 2.19 Wm-1 C-1, produced a mean flux overestimation of 2.33 cm d-1 that, considering the low fluxes of the study area, represents an increase of 89 % and up to a factor of 3 in the most extreme cases. The changes in thermal conductivity can alter the estimated fluxes hindering the detection of patterns in groundwater discharge and modifying the interpretation of the results.

  13. Continuous measurements of water surface height and width along a 6.5km river reach for discharge algorithm development

    NASA Astrophysics Data System (ADS)

    Tuozzolo, S.; Durand, M. T.; Pavelsky, T.; Pentecost, J.

    2015-12-01

    The upcoming Surface Water and Ocean Topography (SWOT) satellite will provide measurements of river width and water surface elevation and slope along continuous swaths of world rivers. Understanding water surface slope and width dynamics in river reaches is important for both developing and validating discharge algorithms to be used on future SWOT data. We collected water surface elevation and river width data along a 6.5km stretch of the Olentangy River in Columbus, Ohio from October to December 2014. Continuous measurements of water surface height were supplemented with periodical river width measurements at twenty sites along the study reach. The water surface slope of the entire reach ranged from during 41.58 cm/km at baseflow to 45.31 cm/km after a storm event. The study reach was also broken into sub-reaches roughly 1km in length to study smaller scale slope dynamics. The furthest upstream sub-reaches are characterized by free-flowing riffle-pool sequences, while the furthest downstream sub-reaches were directly affected by two low-head dams. In the sub-reaches immediately upstream of each dam, baseflow slope is as low as 2 cm/km, while the furthest upstream free-flowing sub-reach has a baseflow slope of 100 cm/km. During high flow events the backwater effect of the dams was observed to propagate upstream: sub-reaches impounded by the dams had increased water surface slopes, while free flowing sub-reaches had decreased water surface slopes. During the largest observed flow event, a stage change of 0.40 m affected sub-reach slopes by as much as 30 cm/km. Further analysis will examine height-width relationships within the study reach and relate cross-sectional flow area to river stage. These relationships can be used in conjunction with slope data to estimate discharge using a modified Manning's equation, and are a core component of discharge algorithms being developed for the SWOT mission.

  14. Fluvial Discharge Rates of Martian Gullies: Slope Measurements From Stereo HiRISE Images and Numerical Modeling of Sediment Transport

    NASA Astrophysics Data System (ADS)

    Parsons, R. A.; Nimmo, F.; Kreslavsky, M.

    2008-12-01

    Using a stereo pair of HiRISE images of a crater slope incised by fourteen gullies at -37.86 N, 217.92 E we calculate relative elevation changes between pairs of hand-selected points. Using the method of Kreslavsky [1]. The background slope on which the gullies are located has a slope of 22 degrees. Out of the five gullies we analyzed, all show a steadily decreasing slope from an average of 30 ± 4 degrees at the alcove to 16 ± 2 degrees at the apron. These measurements are in agreement with previous gully slope measurements done at MOLA resolution in a different region [2]. The slope beyond the base of the gully aprons is 4±1 degrees. The depth of alcove incision in nine of the gullies is 17±8.5~m. We take advantage of this slope and incision data to determine the evolution of a one-dimensional gully profile over time with a 1D sediment transport model [3]. The shear stress applied to the channel bed by flowing water is τ = ρ g h sinθ where h is the channel depth, g is gravity, and h is the channel depth. The rate of transport is non-linearly related to τ/τrg where the reference stress for a gravel bed is τrg = 0.035 ( (s-1)ρ g Dg ) where s is the ratio of sediment to water density, ρ is 1000~m3, and Dg is the sediment grainsize. The two significant unknowns in applying the theory to Martian gullies are the sediment grainsize and channel depth. We ran simulations for various channel depths and grainsizes to get a range of water discharges and simulation times that result in alcoves 25~m deep. Erosion is rapid due to the high slopes; incision rates decrease with decreasing channel depth and increasing grainsize. For grains 20~cm in diameter and a conservatively low channel depth of 20~cm, alcove incision occurs over a 5~h period, discharging a volume of 8500 m3 of water. These discharges assume a 1~m wide channel and a constant, bank-full discharge over the duration of the simulation. Gullies are spaced about every 500~m along the slope. If liquid water

  15. Errors in acoustic doppler profiler velocity measurements caused by flow disturbance

    USGS Publications Warehouse

    Mueller, D.S.; Abad, J.D.; Garcia, C.M.; Gartner, J.W.; Garcia, M.H.; Oberg, K.A.

    2007-01-01

    Acoustic Doppler current profilers (ADCPs) are commonly used to measure streamflow and water velocities in rivers and streams. This paper presents laboratory, field, and numerical model evidence of errors in ADCP measurements caused by flow disturbance. A state-of-the-art three-dimensional computational fluid dynamic model is validated with and used to complement field and laboratory observations of flow disturbance and its effect on measured velocities. Results show that near the instrument, flow velocities measured by the ADCP are neither the undisturbed stream velocity nor the velocity of the flow field around the ADCP. The velocities measured by the ADCP are biased low due to the downward flow near the upstream face of the ADCP and upward recovering flow in the path of downstream transducer, which violate the flow homogeneity assumption used to transform beam velocities into Cartesian velocity components. The magnitude of the bias is dependent on the deployment configuration, the diameter of the instrument, and the approach velocity, and was observed to range from more than 25% at 5cm from the transducers to less than 1% at about 50cm from the transducers for the scenarios simulated. ?? 2007 ASCE.

  16. Optical computer aided tomography measurements of plasma uniformity in an inductively coupled discharge

    SciTech Connect

    Benck, E. C.; Roberts, J. R.

    1998-11-24

    Optical computer aided tomography (CAT) is being investigated as a potential in situ diagnostic for measuring plasma uniformity without making assumptions concerning the plasma symmetry. The presence of an opaque vacuum chamber wall severely limits the different directions from which optical emission measurements can be made of the plasma. The tomographic inversion problem with restricted optical access is being solved using Tikhonov regularization. The accuracy of this inversion process is investigated for several different observation geometries using theoretical test data generated from known distributions. Optical CAT is applied to an ICP-GEC plasma source, with all the measurements made through a single large 152 mm diameter window. Axially asymmetric plasma distributions are demonstrated as a function of gas flow rate and gas composition.

  17. Spectroscopic measurements in low temperature inductively coupled RF discharges in hydrogen

    NASA Astrophysics Data System (ADS)

    Huebschman, Michael Lee

    1999-10-01

    Noninvasive spectroscopic measurements of density and temperature which are characteristic of plasma processing tools have been obtained on inductively driven low- density hydrogen plasma sources. These measurements allow full radial and axial profiles of electron density and temperature to be estimated from absolutely calibrated multichannel spectroscopic measurements of upper state densities and a collisional radiative model that accounts for both collisional and radiative processes. The electron temperature and density were estimated by minimizing the least square deviation of measured population of upper state densities and the prediction of the collisional radiative model. Profiles were obtained over a range of powers from 50 to 200 Watts and pressures from 5 to 50 mTorr in hydrogen in a small cylindrical source. Typical density and temperature measurement profiles have been plotted to characterize the apparatus. An elementary sensitivity analysis, which includes plasma opacity and non- Maxwellian electron distributions, showed that, for hydrogen at processing pressures, the accuracy of the technique is relatively unaffected by these perturbations. The molecular dissociation processes were found to be important in determining the steady state densities of atomic hydrogen but had little affect in populating the upper state hydrogen levels for the plasma conditions measured. A hydrogen working gas and simple geometry were chosen to simplify detailed comparisons with a 2D computational model (INDUCT95) which uses a fluid approximation for the plasma and neutral gas. The code calculates the inductive coupling of the 13.5MHz RIF source and collisional, radiative, and wall losses as well as a complete chemistry model for H2, H, H+, H 3+. Good qualitative agreement between the initial model calculations and experimental data have been obtained over part of the operational range. Lastly, to characterize the apparatus for use in wafer cleaning, radial profiles of the

  18. Spectroscopic and probe measurements of the electron temperature in the plasma of a pulse-periodic microwave discharge in argon

    NASA Astrophysics Data System (ADS)

    Andreev, V. V.; Vasileska, I.; Korneeva, M. A.

    2016-07-01

    A pulse-periodic 2.45-GHz electron-cyclotron resonance plasma source on the basis of a permanent- magnet mirror trap has been constructed and tested. Variations in the discharge parameters and the electron temperature of argon plasma have been investigated in the argon pressure range of 1 × 10-4 to 4 × 10-3 Torr at a net pulsed input microwave power of up to 600 W. The plasma electron temperature in the above ranges of gas pressures and input powers has been measured by a Langmuir probe and determined using optical emission spectroscopy (OES) from the intensity ratios of spectral lines. The OES results agree qualitatively and quantitatively with the data obtained using the double probe.

  19. Measuring bed load discharge in rivers: bedload-surrogate monitoring workshop Minneapolis, Minnesota, 11-14 April 2007

    USGS Publications Warehouse

    Gray, John R.; Laronne, Jonathan B.; Marr, Jeffrey D.G.

    2007-01-01

    The International Bedload-Surrogate Monitoring Workshop (http://www.nced.umn.edu/BRIC_2007.html), organized by the Bedload Research International Cooperative (BRIC; www.bedloadresearch.org), was held to assess and abet progress in continuous, semiautomated, or fully automated (surrogate) technologies for monitoring bed load discharge in gravel-, sand-, and mixed gravel-sand-bedded rivers. Direct bed load measurements, particularly at medium and high flows, during which most bed load occurs, tend to be time-consuming, expensive, and potentially hazardous. Surrogate technologies developed largely over the past decade and used at a number of research sites around the world show considerable promise toward providing relatively dense, robust, and quantifiably reliable bed load data sets. However, information on the efficacy of selected technologies for use in monitoring programs is needed, as is identification of the ways and means for bringing the most promising and practical of the technologies to fruition.

  20. Electron mobility in liquid and supercritical helium measured using corona discharges: a new semi-empirical model for cavity formation.

    PubMed

    Aitken, F; Li, Z-L; Bonifaci, N; Denat, A; von Haeften, K

    2011-01-14

    Electron mobilities in supercritical and liquid helium were investigated as a function of the density. The mobilities were derived from I(V) curves measured in a high-pressure cryogenic cell using a corona discharge in point-plane electrode geometry for charge generation. The presented data spans a wide pressure and temperature range due to the versatility of our experimental set-up. Where data from previous investigations is available for comparison, very good agreement is found. We present a semi-empirical model to calculate electron mobilities both in the liquid and supercritical phase. This model requires the electron-helium scattering length and thermodynamic state equations as the only input and circumvents any need to consider surface tension. Our semi-empirical model reproduces experimental data very well, in particular towards lower densities where transitions from localised to delocalised electron states were observed. PMID:21052578

  1. Correction factor to dye-measured flow velocity under varying water and sediment discharges

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Dye-tracing technique was a widely used method to measure velocity of overland flow in soil erosion studies under both laboratory and field conditions. Few studies were performed to quantify the effects of sediment load on correction factor on steep slopes. The objective was to investigate the poten...

  2. Measurement of axial neutral density profiles in a microwave discharge ion thruster by laser absorption spectroscopy with optical fiber probes

    SciTech Connect

    Tsukizaki, Ryudo; Koizumi, Hiroyuki; Nishiyama, Kazutaka; Kuninaka, Hitoshi

    2011-12-15

    In order to reveal the physical processes taking place within the ''{mu}10'' microwave discharge ion thruster, internal plasma diagnosis is indispensable. However, the ability of metallic probes to access microwave plasmas biased at a high voltage is limited from the standpoints of the disturbance created in the electric field and electrical isolation. In this study, the axial density profiles of excited neutral xenon were successfully measured under ion beam acceleration by using a novel laser absorption spectroscopy system. The target of the measurement was metastable Xe I 5p{sup 5}({sup 2}P{sup 0}{sub 3/2})6s[{sup 3}/{sub 2}]{sup 0}{sub 2} which absorbed a wavelength of 823.16 nm. Signals from laser absorption spectroscopy that swept a single-mode optical fiber probe along the line of sight were differentiated and converted into axial number densities of the metastable neutral particles in the plasma source. These measurements revealed a 10{sup 18} m{sup -3} order of metastable neutral particles situated in the waveguide, which caused two different modes during the operation of the {mu}10 thruster. This paper reports a novel spectroscopic measurement system with axial resolution for microwave plasma sources utilizing optical fiber probes.

  3. Measurement of axial neutral density profiles in a microwave discharge ion thruster by laser absorption spectroscopy with optical fiber probes.

    PubMed

    Tsukizaki, Ryudo; Koizumi, Hiroyuki; Nishiyama, Kazutaka; Kuninaka, Hitoshi

    2011-12-01

    In order to reveal the physical processes taking place within the "μ10" microwave discharge ion thruster, internal plasma diagnosis is indispensable. However, the ability of metallic probes to access microwave plasmas biased at a high voltage is limited from the standpoints of the disturbance created in the electric field and electrical isolation. In this study, the axial density profiles of excited neutral xenon were successfully measured under ion beam acceleration by using a novel laser absorption spectroscopy system. The target of the measurement was metastable Xe I 5p(5)((2)P(0) (3/2))6s[3/2](0) (2) which absorbed a wavelength of 823.16 nm. Signals from laser absorption spectroscopy that swept a single-mode optical fiber probe along the line of sight were differentiated and converted into axial number densities of the metastable neutral particles in the plasma source. These measurements revealed a 10(18) m(-3) order of metastable neutral particles situated in the waveguide, which caused two different modes during the operation of the μ10 thruster. This paper reports a novel spectroscopic measurement system with axial resolution for microwave plasma sources utilizing optical fiber probes. PMID:22225195

  4. A heat-pulse flowmeter for measuring minimal discharge rates in boreholes

    USGS Publications Warehouse

    Hess, A.E.

    1982-01-01

    The U.S. Geological Survey has tested a borehole-configured heat-pulse flowmeter which has good low-velocity flow-measuring sensitivity. The flowmeter was tested in the laboratory in 51-, 102-, and 152-millimeter-diameter columns using water velocities ranging from 0.35 to 250 millimeters per second. The heat-pulse flowmeter also was tested in a 15-meter-deep granite test pit with controlled water flow, and in a 58-meter-deep borehole in sedimentary materials. The flowmeter's capability to detect and measure naturally occurring, low-velocity, thermally induced convection currents in boreholes was demonstrated. Further improvements to the heat-pulse-flowmeter system are needed to increase its reliability and improve its response through four-conductor logging cable.

  5. Energy flux measurements in a steady-state discharge at PSI-2

    NASA Astrophysics Data System (ADS)

    Koch, B.; Bohmeyer, W.; Fussmann, G.; Kornejew, P.; Reiner, H.-D.

    2001-03-01

    A newly developed heat flux detector for direct measurement of the energy flux to a floating or biased target is presented. The detector has been used to measure the plasma sheath transmission factor ( γ) for different gases as a function of the electron temperature. The determined values are in the range of 7< γ<17; they agree roughly with those theoretical predictions [G.A. Emmert, R.M. Wieland, A.T. Mense, J.N. Davidson, Phys. Fluids 23(4) (1980); H. Kimura, H. Maeda, N. Ueda, M. Seki, H. Kawamura, S. Yamamoto, M. Nagami, K. Odajima, S. Sengoku, Y. Shimomura, Nucl. Fusion 18(9) (1978); R.V. Manos, D.M. Budny, S.A. Cohen, J. Vac. Sci. Technol. A 1 (1983); P.C. Stangeby, J. Phys. D 15 (1982); P.C. Stangeby, Phys. Fluids 27(3) 1984] that include the recombination term.

  6. Electron density and gas density measurements in a millimeter-wave discharge

    NASA Astrophysics Data System (ADS)

    Schaub, S. C.; Hummelt, J. S.; Guss, W. C.; Shapiro, M. A.; Temkin, R. J.

    2016-08-01

    Electron density and neutral gas density have been measured in a non-equilibrium air breakdown plasma using optical emission spectroscopy and two-dimensional laser interferometry, respectively. A plasma was created with a focused high frequency microwave beam in air. Experiments were run with 110 GHz and 124.5 GHz microwaves at powers up to 1.2 MW. Microwave pulses were 3 μs long at 110 GHz and 2.2 μs long at 124.5 GHz. Electron density was measured over a pressure range of 25 to 700 Torr as the input microwave power was varied. Electron density was found to be close to the critical density, where the collisional plasma frequency is equal to the microwave frequency, over the pressure range studied and to vary weakly with input power. Neutral gas density was measured over a pressure range from 150 to 750 Torr at power levels high above the threshold for initiating breakdown. The two-dimensional structure of the neutral gas density was resolved. Intense, localized heating was found to occur hundreds of nanoseconds after visible plasma formed. This heating led to neutral gas density reductions of greater than 80% where peak plasma densities occurred. Spatial structure and temporal dynamics of gas heating at atmospheric pressure were found to agree well with published numerical simulations.

  7. Gamma ray measurements during deuterium and /sup 3/He discharges on TFTR

    SciTech Connect

    Cecil, F.E.; Medley, S.S.

    1987-05-01

    Gamma ray count rates and energy spectra have been measured in TFTR deuterium plasmas during ohmic heating and during injection of deuterium neutral beams for total neutron source strengths up to 6 x 10/sup 15/ neutrons per second. The gamma ray measurements for the deuterium plasmas are in general agreement with predictions obtained using simplified transport models. The 16.6 MeV fusion gamma ray from the direct capture reaction D(/sup 3/He,..gamma..)/sup 5/Li was observed during deuterium neutral beam injection into /sup 3/He plasmas for beam powers up to 7 MW. The measured yield of the 16.6 MeV gamma ray is consistent with the predicted yield. The observation of this capture gamma ray establishes the spectroscopy of the fusion gamma rays from the D-/sup 3/He reactions as a viable diagnostic of total fusion reaction rates and benchmarks the modeling for extension of the technique to D-T plasmas. 21 refs., 12 figs.

  8. Spatial measurements of electron energy distribution and plasma parameters in a weakly magnetized inductive discharge

    SciTech Connect

    Kim, Young-Do; Lee, Young-Kwang; Lee, Hyo-Chang; Chung, Chin-Wook

    2013-02-15

    Spatial characteristics of plasma parameters such as electron temperature, plasma density, plasma potential, and electron energy distribution (EED) were studied in inductively coupled plasma with an axial dc magnetic field. With dc magnetic field, the measured EEDs in the total electron energy scale are spatially coincided except cutting of the low electron energy part indicating the conserved non-local electron kinetics in an axial direction, even though the dc magnetic field is applied. Spatial distributions of the plasma densities at axial positions have almost same trends with various magnetic field strengths. We also discuss the reduction of the ambipolar potential along the axial direction as the applied magnetic field increased.

  9. Measurement of vibrationally excited N2(v) in an atmospheric-pressure air pulsed corona discharge using coherent anti-Stokes Raman scattering

    NASA Astrophysics Data System (ADS)

    Teramoto, Yoshiyuki; Ono, Ryo

    2014-08-01

    Vibrationally excited N2(v = 1, 2) in an atmospheric-pressure air pulsed corona discharge was measured using coherent anti-Stokes Raman scattering (CARS). In a dry air discharge, the vibrational temperature determined from the ratio N2(v = 2)/N2(v = 0), Tv2, was approximately 500 K higher than that determined from N2(v = 1)/N2(v = 0), Tv1, immediately after the discharge pulse. Both vibrational temperatures reached equilibrium within 100 μs after the discharge pulse by the vibration-to-vibration (V-V) process of N2-N2. The translational temperature was also measured using CARS. The rise in the translational temperature due to vibration-to-translation (V-T) energy transfer was not observed for a postdischarge time of 5 μs-1 ms in the dry-air discharge. However, when the air was humidified, a significant V-T energy transfer was observed. It was due to an extremely rapid V-T process of H2O-H2O following the V-V process of N2-H2O. Measurements showed that the humidification of the ambient air accelerated the decrease in the N2 vibrational temperature and increased the translational temperature. N2(v) was generated mostly in the secondary streamer, not in the primary one, according to estimation from the measured N2(v) density.

  10. Combined ERT-TDEM measurements for studying submarine groundwater discharge (SGD) at Dor Beach, Israel

    NASA Astrophysics Data System (ADS)

    Levi, E.; Goldman, M.; Weinstein, Y.; Yechieli, Y.

    2008-12-01

    During last years, Dor Beach became a major test site for hydrogeological, geochemical and geophysical investigations of the SGD phenomenon in Israel. The high resolution time-series ERT measurements using 112-m long cable carried out at the site in 2006 have provided important information regarding shallow coastal hydrogeology up to the maximum exploration depth of approximately 20 m (Swarzenski et al, 2006). In a recent experiment (summer 2008), we focused on deeper parts of the site. This goal was achieved by using roughly two times longer shore diagonal and shore perpendicular ERT lines accompanied by onshore TDEM measurements. Such a combination allowed obtaining reliable information regarding the distribution of electrical resistivity up to a maximum depth of approximately 100 m. As a result, an additional high resistivity structure has been detected at a depth of approximately 63 m, which most likely represents the underlying Carmel Cretaceous aquifer saturated with water of lower than seawater salinity. Two saline/freshwater interfaces were detected at depths of approximately 17 m and 49 m. The upper interface between fresh and brackish water was detected by both ERT and TDEM, while the lower fresh/seawater interface was detected by TDEM alone.

  11. Breakdown and Partial Discharge Measurements of Some Commonly Used Dielectric Materials in Liquid Nitrogen for HTS Applications

    SciTech Connect

    James, David Randy; Sauers, Isidor; Ellis, Alvin R; Tuncer, Enis; Tekletsadik, Kasegn; Hazelton, Drew

    2007-01-01

    For high temperature superconducting (HTS) power applications it is necessary to improve the understanding of the dielectric properties of materials in a cryogenic environment. It is necessary to know the breakdown strength of materials and systems as a function of gap in order to scale to higher voltages. The partial discharge (PD) onset voltage for materials is also very important since the primary aging mechanism at cryogenic temperature is PD. Another important design characteristic is the surface flashover voltage of a material in liquid nitrogen as a function of gap. With these characteristics in mind, several generic materials were investigated under a variety of electrode and gap configurations. The impulse breakdown voltage and PD onset of three types of commercial polyetherimide, filled and unfilled, were measured at room temperature and 77 K. A modest increase in PD onset voltage was observed at the lower temperature. Breakdown voltages of fiberglass reinforced plastic (FRP) cylinders for two wall thicknesses were measured which showed a decrease in strength at the larger gap. Breakdown voltages for liquid nitrogen using a sphere-plane electrode geometry were measured. Also flashover voltages along a FRP plate immersed in liquid nitrogen were performed for sphere-plane and rod-plane electrodes at 1 bar pressure. It was found that the breakdown voltage increased only slightly with increasing gap lengths.

  12. A Validation of the Spectral Power Clustering Technique (SPCT) by Using a Rogowski Coil in Partial Discharge Measurements

    PubMed Central

    Ardila-Rey, Jorge Alfredo; Albarracín, Ricardo; Álvarez, Fernando; Barrueto, Aldo

    2015-01-01

    Both in industrial as in controlled environments, such as high-voltage laboratories, pulses from multiple sources, including partial discharges (PD) and electrical noise can be superimposed. These circumstances can modify and alter the results of PD measurements and, what is more, they can lead to misinterpretation. The spectral power clustering technique (SPCT) allows separating PD sources and electrical noise through the two-dimensional representation (power ratio map or PR map) of the relative spectral power in two intervals, high and low frequency, calculated for each pulse captured with broadband sensors. This method allows to clearly distinguishing each of the effects of noise and PD, making it easy discrimination of all sources. In this paper, the separation ability of the SPCT clustering technique when using a Rogowski coil for PD measurements is evaluated. Different parameters were studied in order to establish which of them could help for improving the manual selection of the separation intervals, thus enabling a better separation of clusters. The signal processing can be performed during the measurements or in a further analysis. PMID:26473872

  13. A validation of the spectral power clustering technique (SPCT) by using a Rogowski coil in partial discharge measurements.

    PubMed

    Ardila-Rey, Jorge Alfredo; Albarracín, Ricardo; Álvarez, Fernando; Barrueto, Aldo

    2015-01-01

    Both in industrial as in controlled environments, such as high-voltage laboratories, pulses from multiple sources, including partial discharges (PD) and electrical noise can be superimposed. These circumstances can modify and alter the results of PD measurements and, what is more, they can lead to misinterpretation. The spectral power clustering technique (SPCT) allows separating PD sources and electrical noise through the two-dimensional representation (power ratio map or PR map) of the relative spectral power in two intervals, high and low frequency, calculated for each pulse captured with broadband sensors. This method allows to clearly distinguishing each of the effects of noise and PD, making it easy discrimination of all sources. In this paper, the separation ability of the SPCT clustering technique when using a Rogowski coil for PD measurements is evaluated. Different parameters were studied in order to establish which of them could help for improving the manual selection of the separation intervals, thus enabling a better separation of clusters. The signal processing can be performed during the measurements or in a further analysis. PMID:26473872

  14. A post-discharge functional outcome measure for lower limb amputees: test-retest reliability with trans-tibial amputees.

    PubMed

    Callaghan, B G; Sockalingam, S; Treweek, S P; Condie, M E

    2002-08-01

    There are approximately 700 lower limb amputations performed throughout Scotland each year. A national system of survey and analysis conducted by the Scottish Physiotherapy Amputee Research Group (SPARG) provides information on these patients up until discharge from hospital. However, there has been no method of collecting long-term functional and prosthetic use information following discharge. The Functional Measure for Amputees (FMA) has, therefore, been developed from the Prosthetic Profile of the Amputee (PPA) questionnaire, designed by Gauthier-Gagnon and colleagues in Canada (Grisé et al, 1993). Modifications to the PPA were carried out to make it more appropriate for the Scottish amputee population; these changes were approved by the original authors. The test-retest reliability of the 14-question FMA was assessed using a repeat postal questionnaire study. One hundred and thirty-three (133) from a possible 390 trans-tibial amputees were returned. Comparing sociodemographic and clinical variables between consenters and non-consenters showed no evidence to support sample bias. Continuous data items on the FMA analysed using an intraclass correlation coefficient showed ICC values of 0.74, 0.85, 0.96 and 0.64. Categorical data items analysed using percentage agreements showed reliability of over 70% for seven items, between 40% and 70% for three items and between 20% and 40% for the remaining three items. The FMA questionnaire was found to be reliable on the majority of its questions and moderately reliable on the remaining questions during successive follow-up postal administrations. PMID:12227445

  15. Near bottom velocity measurements in San Francisco Bay, California

    USGS Publications Warehouse

    Gartner, Jeffrey W.; Cheng, Ralph T.

    1996-01-01

    The ability to accurately measure long-term time-series of tidal currents in bays and estuaries is critical in estuarine hydrodynamic studies. Accurate measurements of tidal currents near the air-water interface and in the bottom boundary layer remain difficult in spite of the significant advances in technology for measuring tidal currents which have been achieved in recent years. One of the objectives of this study is to demonstrate that turbulent mean velocity distribution within the bottom boundary layer can be determined accurately by using a broad-band acoustic Doppler current profiler (BB-ADCP). A suite of instruments, including two BB-ADCPs and four electromagnetic (EM) current meters was deployed in San Francisco Bay, California in an investigation of resuspension and transport of sediment during March 1995. The velocity measurements obtained in the bottom boundary layer by BB-ADCP were highly coherent (r2>0.94) with the velocity measurements obtained by EM current meters. During early March 1995, both BB-ADCPs and EM current meters recorded a very unusual flow event. Agreement among independent measurements by these instruments in describing such an atypical hydrodynamic occurrence further validates the velocity measurements obtained by BB-ADCP in the bottom boundary layer.

  16. Cars temperature measurements and stability studies of a d. c. nitrogen discharge. Final report, September 1989-July 1991. [CARS (coherent anti-Stokes Raman spectroscopy)

    SciTech Connect

    Millard, M.

    1991-07-01

    The vibrational and rotational temperatures of a 30-Torr, normal glow N2 gas discharge have been measured using a coherent anti-Stokes Raman spectroscopy system in the folded BOXCARS configuration. The discharge was set up in slowly flowing nitrogen between two plane parallel molybdenum electrodes. Current densities of O.047 A/sq cm were used with an E/N of approximately 50 Td. The nearly wall-less discharge was stabilized using a Macor ceramic cap covering the cathode with a 9-mm circular aperture in the center. Measurements were made at spatially resolved locations within the discharge both axially and radially. Theoretical spectra were fit to experimental data in order to obtain the rotational and vibrational temperatures and the relative populations. A detailed study of the spectral line shape of the dye laser used as the probe beam in the CARS system was carried out using the optogalvanic effect in a Fe-Ne hollow-cathode lamp. The spectral line width and lineshape under differing dye pumping schemes were obtained. These measured line widths were greater than expected and showed a non-Gaussian profile for the probe laser. Stability of the nitrogen discharge was also studied in order to determine the conditions under which the discharge remains stable. Instability was noted visually, in the behavior of the CARS signal and the electrode voltage, both of which showed hysteresis. In order to make way for changes in the system in the future, a new CARS system was designed which will allow study of various gasses under differing discharge conditions.

  17. Characterization of the Spatial and Temporal Variations of Submarine Groundwater Discharge Using Electrical Resistivity and Seepage Measurements

    NASA Astrophysics Data System (ADS)

    Durand, Josephine Miryam Kalyanie

    Submarine groundwater discharge (SGD) encompasses all fluids crossing the sediment/ocean interface, regardless of their origin, composition or driving forces. SGD provides a pathway for terrestrial contaminants that can significantly impact coastal ecosystems. Overexploitation of groundwater resources can decrease SGD which favors seawater intrusion at depth. Understanding SGD is therefore crucial for water quality and resource management. Quantifying SGD is challenging due to its diffuse and heterogeneous nature, in addition to significant spatio-temporal variations at multiple scales. In this thesis, an integrated approach combining electrical resistivity (ER) surveys, conductivity and temperature point measurements, seepage rates using manual and ultrasonic seepage meters, and pore fluid salinities was used to characterize SGD spatio-temporal variations and their implications for contaminant transport at several locations on Long Island, NY. The influence of surficial sediments on SGD distribution was investigated in Stony Brook Harbor. A low-permeability mud layer, actively depositing in the harbor, limits SGD at the shoreline, prevents mixing with seawater and channels a significant volume of freshwater offshore. SGD measured at locations without mud is high and indicates significant mixing between porewater and seawater. A 2D steady-state density-difference numerical model of the harbor was developed using SEAWAT and was validated by our field observations. Temporal variations of SGD due to semi-diurnal tidal forcing were studied in West Neck Bay, Shelter Island, using a 12-hr time-lapse ER survey together with continuous salinity and seepage measurements in the intertidal zone. The observed dynamic patterns of groundwater flux and salinity distribution disagree with published standard transient state numerical models, suggesting the need for developing more specific models of non-homogeneous anisotropic aquifers. SGD distribution and composition were

  18. Electron energy distribution functions measured by Langmuir probe with optical emission spectroscopy in very high frequency capacitive discharge in nitrogen

    SciTech Connect

    Abdel-Fattah, E.; Bazavan, M.; Sugai, H.

    2012-11-15

    By using a rf compensated Langmuir probe and optical emission spectroscopy, the effects of driving frequency (13.56-50 MHz) on the electron energy probability function (EEPF), electron density, electron temperature, and the vibrational and rotational temperatures in capacitively coupled nitrogen discharge were investigated. Measurements were performed in the pressure range 60-200 mTorr, and at a fixed voltage of 140 V (peak-to-peak). With increasing the driving frequency, the dissipated power and electron density markedly increased along with the intensity of the optical emission lines belonging to the 2nd positive (337.1 nm) and 1st negative systems (391.4 nm) of N{sub 2}. The EEPF at low pressure 60 mTorr is two-temperature (bi-Maxwellian) distribution, irrespective of the driving frequency, in contrast with argon and helium discharges in the similar conditions. The mechanism forming such bi-Maxwellian shape was explained by two combined effects: one is the collisionless sheath-heating effect enhancing the tail electron population, and the other is the collision-induced reduction of electrons at the energy 2-4 eV where the collision cross-section for the vibrational excitation has a resonantly large peak. The two-temperature EEPF structure was basically retained at moderate pressure 120 mTorr and high pressure 200 mTorr. The vibrational temperature T{sub vib} and rotational temperature T{sub rot} are measured for the sequence ({Delta}{nu}=-2) of N{sub 2} second positive system (C{sup 3}{Pi}{sub u}{yields}B{sup 3}{Pi}{sub g}) using the method of comparing the measured and calculated spectra with a chi-squared minimization procedure. It was found that, both of T{sub vib} and T{sub rot} are a weakly dependent on driving frequency at low pressure 60 mTorr. At higher pressure (120 and 200 mTorr), T{sub vib} rises monotonically with the driving frequency, whereas the T{sub rot} slightly decreases with frequency below 37 MHz, beyond which it relatively increases or

  19. Vaginal Discharge

    MedlinePlus

    ... also be on the lookout for symptoms of yeast infections, bacterial vaginosis and trichomoniasis, 3 infections that ... cause changes in your vaginal discharge. Signs of yeast infections White, cottage cheese-like discharge Swelling and ...

  20. Measurement and estimation of radiocesium discharge rate from paddy field during land preparation and mid-summer drainage.

    PubMed

    Miyazu, Susumu; Yasutaka, Tetsuo; Yoshikawa, Natsuki; Tamaki, Shouhei; Nakajima, Kousei; Sato, Iku; Nonaka, Masanori; Harada, Naoki

    2016-05-01

    In this research, we evaluated the range of (137)Cs discharge rates from paddy fields during land preparation and mid-summer drainage. First, we investigated (137)Cs discharge loads during land preparation and mid-summer drainage and their ratio to the (137)Cs inventory of paddy field soil. We found that total discharge rates were 0.003-0.028% during land preparation and 0.001-0.011% during mid-summer drainage. Next, we validated the range of obtained total discharge of (137)Cs from the paddy fields using a simplified equation and literature review. As a result, we conclude that the range of total outflow loads of suspended solids for the investigated paddy field was generally representative of paddy fields in Japan. Moreover, the (137)Cs discharge ratio had a wide range, but was extremely small relative to (137)Cs present in paddy field soil before irrigation. PMID:26895347

  1. Nitric oxide density measurements in air and air/fuel nanosecond pulse discharges by laser induced fluorescence

    NASA Astrophysics Data System (ADS)

    Uddi, M.; Jiang, N.; Adamovich, I. V.; Lempert, W. R.

    2009-04-01

    Laser induced fluorescence is used to measure absolute nitric oxide concentrations in air, methane-air and ethylene-air non-equilibrium plasmas, as a function of time after initiation of a single pulse, 20 kV peak voltage, 25 ns pulse duration discharge. A mixture of NO and nitrogen with known composition (4.18 ppm NO) is used for calibration. Peak NO density in air at 60 Torr, after a single pulse, is ~8 × 1012 cm-3 (~4.14 ppm) occurring at ~250 µs after the pulse, with decay time of ~16.5 ms. Peak NO atom mole fraction in a methane-air mixture with equivalence ratio of phiv = 0.5 is found to be approximately equal to that in air, with approximately the same rise and decay rate. In an ethylene-air mixture (also with equivalence ratio of phiv = 0.5), the rise and decay times are comparable to air and methane-air, but the peak NO concentration is reduced by a factor of approximately 2.5. Spontaneous emission measurements show that excited electronic states N2(C 3Π) and NO(A 2Σ) in air at P = 60 Torr decay within ~20 ns and ~1 µs, respectively. Kinetic modelling calculations incorporating air plasma kinetics complemented with the GRI Mech 3.0 hydrocarbon oxidation mechanism are compared with the experimental data using three different NO production mechanisms. It is found that NO concentration rise after the discharge pulse is much faster than predicted by Zel'dovich mechanism reactions, by two orders of magnitude, but much slower compared with reactions of electronically excited nitrogen atoms and molecules, also by two orders of magnitude. It is concluded that processes involving long lifetime (~100 µs) metastable states, such as N2(X 1Σ,v) and O2(b 1Σ), formed by quenching of the metastable N2(A 3Σ) state by ground electronic state O2, may play a dominant role in NO formation. NO decay, in all cases, is found to be dominated by the reverse Zel'dovich reaction, NO + O → N + O2, as well as by conversion into NO2 in a reaction of NO with ozone.

  2. Examination of Direct Discharge Measurement Data and Historic Daily Data for Selected Gages on the Middle Mississippi River, 1861-2008

    USGS Publications Warehouse

    Huizinga, Richard J.

    2009-01-01

    An examination of data from two continuous stage and discharge streamgages and one continuous stage-only gage on the Middle Mississippi River was made to determine stage-discharge relation changes through time and to investigate cause-and-effect mechanisms through evaluation of hydraulic geometry, channel elevation and water-surface elevation data. Data from discrete, direct measurements at the streamgages at St. Louis, Missouri, and Chester, Illinois, during the period of operation by the U.S. Geological Survey from 1933 to 2008 were examined for changes with time. Daily stage values from the streamgages at St. Louis (1861-2008) and Chester (1891-2008) and the stage-only gage at Cape Girardeau, Missouri (1896-2008), throughout the historic period of record also were examined for changes with time. Stage and discharge from measurements and stage-discharge relations at the streamgages at St. Louis and Chester indicate that stage for a given discharge has changed with time at both locations. An apparent increase in stage for a given discharge at increased flows (greater than flood stage) likely is caused by the raising of levees on the flood plains, and a decrease in stage for a given discharge at low flows (less than one-half flood stage) likely is caused by a combination of dikes in the channel that deepen the channel thalweg at the end of the dikes, and reduced sediment flux into the Middle Mississippi River. Since the 1960s at St. Louis, Missouri, the stage-discharge relations indicated no change or a decrease in stage for a given discharge for all discharges, whereas at Chester, Illinois, the stage-discharge relations indicate increasing stage for a given discharge above bankfull because of sediment infilling of the overflow channel. Top width and average velocity from measurements at a given discharge for the streamgage at St. Louis, Missouri, were relatively constant through time, with the only substantial change in top width resulting from the change in

  3. Periodic Evolution of a Xe I Population in an Oscillatory Discharge: Comparison between Time-Synchronized Laser-Induced-Fluorescence Measurements and A Dynamic Collisional-Radiative Model

    NASA Astrophysics Data System (ADS)

    Lucca Fabris, Andrea; Young, Chris V.; Cappelli, Mark A.; Plasma Physics Laboratory Team

    2014-10-01

    We study the evolution of the Xe I 6 s '[ 1 / 2 ] 1 - 6 p '[ 3 / 2 ] 2 (834.68 nm air) transition lineshape in a plasma discharge oscillating at 60 Hz using time-synchronized laser induced fluorescence (LIF) measurements and a collisional-radiative model. Two different time-synchronized LIF techniques based on phase sensitive detection of the fluorescence signal are applied, yielding consistent results. The maximum observed peak fluorescence intensity occurs at low values of the discharge current, although the peak intensity drops to zero at zero discharge current. The peak intensity also decreases at the discharge current maximum. A dynamic collisional-radiative model of the weakly ionized xenon discharge is also implemented, based on a set of rate equations. The proper electron impact cross-sections and radiative decay rates are identified from the literature and used to compute accurate rate coefficients with the Boltzmann solver Bolsig+, including the time-varying electric field. The time evolution of the probed excited state density predicted by the model shows good agreement with the experimental measurements. This work is sponsored by the U.S. Air Force Office of Scientific Research with Dr. Mitat Birkan as program manager. CVY acknowledges support from the DOE NNSA Stewardship Science Graduate Fellowship under Contract DE-FC52-08NA28752.

  4. Comparison of index velocity measurements made with a horizontal acoustic Doppler current profiler

    USGS Publications Warehouse

    Jackson, P. Ryan; Johnson, Kevin K.; Duncker, James J.

    2012-01-01

    The State of Illinois' annual withdrawal from Lake Michigan is limited by a U.S. Supreme Court decree, and the U.S. Geological Survey (USGS) is responsible for monitoring flows in the Chicago Sanitary and Ship Canal (CSSC) near Lemont, Illinois as a part of the Lake Michigan Diversion Accounting overseen by the U.S. Army Corps of Engineers, Chicago District. Every 5 years, a technical review committee consisting of practicing engineers and academics is convened to review the U.S. Geological Survey's streamgage practices in the CSSC near Lemont, Illinois. The sixth technical review committee raised a number of questions concerning the flows and streamgage practices in the CSSC near Lemont and this report provides answers to many of those questions. In addition, it is the purpose of this report to examine the index velocity meters in use at Lemont and determine whether the acoustic velocity meter (AVM), which is now the primary index velocity meter, can be replaced by the horizontal acoustic Doppler current profiler (H-ADCP), which is currently the backup meter. Application of the AVM and H-ADCP to index velocity measurements in the CSSC near Lemont, Illinois, has produced good ratings to date. The site is well suited to index velocity measurements in spite of the large range of velocities and highly unsteady flows at the site. Flow variability arises from a range of sources: operation of the waterway through control structures, lockage-generated disturbances, commercial and recreational traffic, industrial withdrawals and discharges, natural inflows, seiches, and storm events. The influences of these factors on the index velocity measurements at Lemont is examined in detail in this report. Results of detailed data comparisons and flow analyses show that use of bank-mounted instrumentation such as the AVM and H-ADCP appears to be the best option for index velocity measurement in the CSSC near Lemont. Comparison of the rating curves for the AVM and H-ADCP demonstrates

  5. Bone marrow transplant - discharge

    MedlinePlus

    Transplant - bone marrow - discharge; Stem cell transplant - discharge; Hematopoietic stem cell transplant - discharge; Reduced intensity; Non-myeloablative transplant - discharge; Mini transplant - discharge; Allogenic bone marrow transplant - ...

  6. Hip fracture - discharge

    MedlinePlus

    Inter-trochanteric fracture repair - discharge; Subtrochanteric fracture repair - discharge; Femoral neck fracture repair - discharge; Trochanteric fracture repair - discharge; Hip pinning surgery - discharge

  7. A systematic test of surface velocity radar (SVR) to improve flood discharge prediction

    NASA Astrophysics Data System (ADS)

    Zolezzi, G.; Zamler, D.; Laronne, J. B.; Salvaro, M.; Piazza, F.; Le Coz, J.; Welber, M.; Dramais, G.

    2011-12-01

    Measurement of streamflow at flood stage is normally prohibitive and is therefore not a standard task performed by hydrographic offices. Streamflow estimation at high stages is commonly achieved through transformation of gauged water levels to discharge through rating curves. These stage-discharge relationships often suffer from large errors especially above the highest gauged discharge values corresponding to morphologically formative conditions. Non-contact methods based on radar Doppler technology have recently emerged as promising options because they can remotely measure the surface water velocity without requiring contact of instruments with the stream. They have been used for more than a decade, notably in Japan, but they are expensive and are fixed with the radar beam directed to a small portion of the free surface width. The aim of our study is to test a portable, cheap, easy-to-apply radar-based technique (SVR: Surface Velocity Radar). We illustrate the outcomes of a systematic series of field campaigns performed in Israel, Italy and France with concomitant standard (mechanical and electromagnetic current meter) and modern (ADCP, LSPIV image analysis) techniques with cooperating regional authorities. The SVR has been deployed from bridges and/or channel banks on 5 different streams: the single-thread Adige and the braided Tagliamento rivers (NE Italy) the single-thread Arc-en-Maurienne River during reservoir flushing (French Alps) and the ephemeral, flashflood Wadi Eshtemoa and a small perennial stream at Ein-Fesh'ha springs (Israel). This has allowed to span a relatively broad range of discharge (1 to ~ 600 m3/s), flow velocity (0.5 to ~ 3.5 m/s) and ratio between bed roughness height to flow depth (~ 0.01 to ~ 0.5) while measuring both under steady and rapidly varying flow conditions. The key outcomes of the field campaigns are: (i) wherever a bridge is available and cross-sectional topography can be measured before and/or after a flood, comparable

  8. Measurement of ion density in an atmospheric pressure argon with pin-to-plate dielectric barrier discharge by resonance of plasma radiation

    SciTech Connect

    Qi, Bing Pan, Lizhu; Zhou, Qiujiao; Huang, Jianjun; Liu, Ying

    2014-12-15

    The measurements of the ion densities in the atmospheric AC barrier corona argon discharge are carried out by receiving and analyzing the frequencies of the electromagnetic radiation emitted from the plasma. An auxiliary excitation source composed of a pin-to-pin discharge system is introduced to excite the oscillations of the main discharge. To analyze the resonance mechanism, a complemented model based on a one-dimensional description of forced vibrations is given. Calculations indicate that Ar{sub 2}{sup +} is the dominant ion (∼89% in number density). By analyzing resonance frequencies, the ion densities of Ar{sub 2}{sup +} are in the order of 10{sup 19}∼10{sup 20}m{sup −3} and increase slowly as the applied voltage increases.

  9. Silane discharge ion chemistry

    SciTech Connect

    Chatham, R.H. III

    1984-01-01

    Silane dc, rf, and dc proximity discharges have been studied using mass spectroscopic measurements of the positive ions as a detailed diagnostic for the type of discharge used to produce hydrogenated amorphous silicon solar photovoltaic cells. The properties and quality of these films depends in a very complex way upon the interactions of the many reactive neutral and ion species in the discharge. Qualitative models of the ion chemical processes in these discharges have been developed from experimental measurements. Knowledge of the ion-molecule and electron-molecule collision cross sections is important to any attempt at understanding silane discharge chemistry. Consequently, the electron impact ionization cross sections for silane and disilane have been measured and for comparison purposes also for methane and ethane. In addition, the rate coefficients for charge exchange reactions of He , Ne , and Ar with silane, disilane, methane, and ethane have been measured as these are important to understanding discharges in inert gas-silane mixtures. A detailed quantitative model of the cathode sheath region of a silane dc discharge has been developed by extending the best recent calculation of the electron motion in the sheath to a self-consistent form which includes the ion motion. This model is used with comparison of silane dc discharge data to diagnose the ion chemistry occurring in the sheath region of silane dc discharge. The understanding of the discharge ion chemical processes that have been gained in this study represent an important step toward understanding the chemical and physical processes leading to film growth.

  10. Angina - discharge

    MedlinePlus

    ... bypass surgery - minimally invasive - discharge Heart disease - risk factors High ... of Cardiology, Harborview Medical Center, University of Washington Medical School, Seattle, WA. Also reviewed ...

  11. Discharging patients.

    PubMed

    Causey, Amy

    2016-06-22

    What was the nature of the CPD activity and/or practice-related feedback and/or event or experience in your practice? The CPD article discussed the importance of effective planning when discharging patients from acute care hospitals. It emphasised the benefit of early assessment and planning, and outlined the essential principles that should be followed when discharging a patient. PMID:27332612

  12. Looking to the Future: Non-contact Methods for Measuring Streamflow

    USGS Publications Warehouse

    Costa, J.E.; Cheng, R.T.; Haeni, F.P.; Melcher, N.B.; Spicer, K.R.; Plant, J.; Keller, W.C.; Hayes, K.

    2002-01-01

    We have conducted a series of proof-of-concept experiments to demonstrate whether it is possible to make completely non-contact open-channel discharge measurements. After an extensive evaluation of potential technologies, we concluded a combination of high-frequency (microwave) radar (for measuring surface velocity) and low-frequency radar (ground-penetrating radar) for measuring channel cross-section, had the best chance for success. The first experiment in 1999 on the Skagit River, Washington, using non-contact methods, produced a discharge value nearly exactly the same as from an ADCP and current meter. Surface-velocity data were converted to mean velocity based on measurements of the velocity profile (multiplied by 0.85), and radar signal speed in impure fresh water was measured to be 0.11-0.12 ft/ns. The weak link was thought to be the requirement to suspend the GPR antenna over the water, which required a bridge or cableway. Two contractors, expert with radar, were unsuccessful in field experiments to measure channel cross-section from the riverbank. Another series of experiments were designed to demonstrate whether both radar systems could be mounted on a helicopter, flown back and forth across a river, and provide data to compute flow. In Sept. 2000 and May 2001, a series of helicopter flights with mounted radar systems successfully measured surface velocity and channel cross-section of the Cowlitz River, Washington.

  13. Groundwater discharge to wetlands driven by storm and flood events: Quantification using continuous Radon-222 and electrical conductivity measurements and dynamic mass-balance modelling

    NASA Astrophysics Data System (ADS)

    Gilfedder, B. S.; Frei, S.; Hofmann, H.; Cartwright, I.

    2015-09-01

    The dynamic response of groundwater discharge to external influences such as rainfall is an often neglected part of water and solute balances in wetlands. Here we develop a new field platform for long-term continuous 222Rn and electrical conductivity (EC) measurements at Sale Wetland, Australia to study the response of groundwater discharge to storm and flood events. The field measurements, combined with dynamic mass-balance modelling, demonstrate that the groundwater flux can increase from 3 to ∼20 mm d-1 following storms and up to 5 mm d-1 on the receding limb of floods. The groundwater pulses are likely produced by activation of local groundwater flow paths by water ponding on the surrounding flood plains. While 222Rn is a sensitive tracer for quantifying transient groundwater discharge, the mass-balance used to estimate fluxes is sensitive to parameterisation of gas exchange (k) with the atmosphere. Comparison of six equations for calculating k showed that, based on parameterisation of k alone, the groundwater flux estimate could vary by 58%. This work shows that neglecting transient processes will lead to errors in water and solute flux estimates based on infrequent point measurements. This could be particularly important for surface waters connected to contaminated or saline groundwater systems.

  14. Energy- and time-resolved measurements of fast ions emitted from plasma-focus discharges by means of a Thomson spectrometer

    NASA Astrophysics Data System (ADS)

    Kwiatkowski, R.; Czaus, K.; Paduch, M.; Sadowski, M. J.; Skladnik-Sadowska, E.; Zaloga, D. R.; Zielinska, E.; Żebrowski, J.

    2015-09-01

    The paper presents results of time-resolved measurements of fast deuterons emitted from high-current discharges of the Plasma-Focus (PF) type. The measurements were performed in a modified PF-1000U facility which is operated at the IFPiLM in Warsaw, Poland. The device was equipped with a fast-acting gas valve placed inside the inner electrode and oriented along the z-axis. The valve could inject a small volume of a chosen gas in front of this electrode. The PF discharges were initiated at the initial deuterium pressure equal to 1.6 or 2 hPa, with or without the use of the gas-puffing. Such discharges emitted intense beams of accelerated primary ions and X-ray pulses as well as products of nuclear fusion reactions. The reported measurements of the fast ion beams were performed by means of a Thomson-type spectrometer located at a chosen distance at the z-axis and equipped with miniature scintillation detectors. These detectors were placed in different points upon the deuteron parabola which corresponded to determined energy values. The detectors configuration allowed us to determine instants of the ion emission (using a TOF technique) and to compare them with instants of the X-ray emission. The collected data provided important information about emission characteristics of the modified PF-1000U facility.

  15. [Nipple discharge].

    PubMed

    Deodato, G; Consoli, A; Riggi, M; Longo, G; Finocchiaro, G B

    1981-02-01

    The Authors examine the various types of breast discharge concentrating in particular on the secretions due to inherent pathology. After having studied origin, they concentrate on the diagnostic significance and the limits of exfoliative cytology and contrast mammography. The Authors conclude by presenting an original protocol of treatment of the afflicted breast illustrating in addition, the various surgical techniques proposed for the cure of the sicknesses of intramammary origin that cause abnormal discharge. PMID:7261200

  16. Measurement of OH, O, and NO densities and their correlations with mouse melanoma cell death rate treated by a nanosecond pulsed streamer discharge

    NASA Astrophysics Data System (ADS)

    Yagi, Ippei; Shirakawa, Yuki; Hirakata, Kenta; Akiyama, Taketoshi; Yonemori, Seiya; Mizuno, Kazue; Ono, Ryo; Oda, Tetsuji

    2015-10-01

    Mouse melanoma cells in a culture medium are treated using a nanosecond pulsed streamer discharge plasma and the correlations between the rate of cell death and the densities of reactive species (OH, O, and NO) in the plasma are measured. The plasma is irradiated onto the culture medium surface with a vertical gas flow of an O2/N2 mixture from a glass tube at various gas flow rates and O2 concentrations. The densities of the reactive species are measured very close to the culture medium surface, where the reactive species interact with the culture medium, using laser-induced fluorescence. In the case of the N2 discharge (O2 = 0%), an increase in gas flow rate decreases OH density because it lowers the water vapor concentration by diluting the vapor, which is required for OH production. The increase in gas flow rate also leads to a decreased cell death rate. In the case of the O2/N2 discharge, on the other hand, an increase in O2 concentration at a fixed flow rate does not affect the rate of cell death, although it considerably changes the O and NO densities. These findings indicate that some reactive species derived from water vapor such as OH are responsible for the melanoma cell death, whereas those from O2, such as O and NO, are less likely responsible. They also indicate the importance of water evaporation from the culture medium surface in cell treatment.

  17. Picosecond CARS measurements of nitrogen vibrational loading and rotational/translational temperature in non-equilibrium discharges

    NASA Astrophysics Data System (ADS)

    Montello, A.; Yin, Z.; Burnette, D.; Adamovich, I. V.; Lempert, W. R.

    2013-11-01

    Picosecond coherent anti-Stokes Raman spectroscopy (CARS) is used to study vibrational energy loading and relaxation kinetics in nitrogen and air ns pulsed non-equilibrium plasmas, in both plane-to-plane and pin-to-pin geometries. In 10 kHz repetitively pulsed plane-to-plane plasmas, up to ˜50% of coupled discharge power is found to load vibrations, in good agreement with a master equation kinetic model. In the pin-to-pin geometry, ˜40% of total discharge energy in a single pulse in air at 100 Torr is found to couple directly to nitrogen vibrations by electron impact, also in good agreement with model predictions. Post-discharge, the total quanta in vibrational levels v = 0-9 is found to increase by ˜60% in air and by a factor of ˜3 in nitrogen, respectively, a result in direct contrast to modelling results which predict the total number of quanta to be essentially constant until ultimately decaying by V-T relaxation and mass diffusion. More detailed comparison between experiment and model show that the vibrational distribution function (VDF) predicted by the model during, and directly after, the discharge pulse is in good agreement with that determined experimentally. However, for time delays exceeding ˜1 µs, the experimental VDF shows populations of vibrational levels v ⩾ 2 greatly exceeding modelling results, which predict their predominant decay due to net downward V-V transfer and corresponding increase in v = 1 population. This is at variance with the experimental results, which show a significant monotonic increase in the populations of levels v = 2-9 at t ˜ 1-10 µs after the discharge pulse, both in nitrogen and air, before gradually switching to relaxation at t ˜ 10-100 µs. It is concluded that a collisional process is likely feeding high vibrational levels at a rate which is comparable to the rate at which population of the high levels is lost due to net downward V-V energy transfer. A likely candidate for the source of additional vibrational

  18. Assessing the potential impact of water-based drill cuttings on deep-water calcareous red algae using species specific impact categories and measured oceanographic and discharge data.

    PubMed

    Nilssen, Ingunn; dos Santos, Francisco; Coutinho, Ricardo; Gomes, Natalia; Cabral, Marcelo Montenegro; Eide, Ingvar; Figueiredo, Marcia A O; Johnsen, Geir; Johnsen, Ståle

    2015-12-01

    The potential impact of drill cuttings on the two deep water calcareous red algae Mesophyllum engelhartii and Lithothamnion sp. from the Peregrino oil field was assessed. Dispersion modelling of drill cuttings was performed for a two year period using measured oceanographic and discharge data with 24 h resolution. The model was also used to assess the impact on the two algae species using four species specific impact categories: No, minor, medium and severe impact. The corresponding intervals for photosynthetic efficiency (ΦPSIImax) and sediment coverage were obtained from exposure-response relationship for photosynthetic efficiency as function of sediment coverage for the two algae species. The temporal resolution enabled more accurate model predictions as short-term changes in discharges and environmental conditions could be detected. The assessment shows that there is a patchy risk for severe impact on the calcareous algae stretching across the transitional zone and into the calcareous algae bed at Peregrino. PMID:26412110

  19. Charge transferred in brush discharges

    NASA Astrophysics Data System (ADS)

    Talarek, M.; Kacprzyk, R.

    2015-10-01

    Electrostatic discharges from surfaces of plastic materials can be a source of ignition, when appear in explosive atmospheres. Incendivity of electrostatic discharges can be estimated using the transferred charge test. In the case of brush discharges not all the energy stored at the tested sample is released and the effective surface charge density (or surface potential) crater is observed after the discharge. Simplified model, enabling calculation of a charge transferred during electrostatic brush discharge, was presented. Comparison of the results obtained from the simplified model and from direct measurements of transferred charge are presented in the paper.

  20. OH kinetic in high-pressure plasmas of atmospheric gases containing C2H6 studied by absolute measurement of the radical density in a pulsed homogeneous discharge

    NASA Astrophysics Data System (ADS)

    Magne, L.; Pasquiers, S.; Gadonna, K.; Jeanney, P.; Blin-Simiand, N.; Jorand, F.; Postel, C.

    2009-08-01

    The absolute value of the hydroxyl radical was measured in the afterglow of an homogeneous photo-triggered discharge generated in N2/O2/H2O/C2H6 mixtures, using a UV absorption diagnostic synchronized with the discharge current pulse. Measurements show that OH is efficiently produced even in the absence of water vapour in the mixture, and that the radical production is closely linked to the degradation kinetic of the hydrocarbon. Experimental results for dry mixtures, both for OH and for the removal of ethane in the discharge volume, are compared with predictions of a self-consistent 0D discharge and the kinetic model. It appears that the oxidation reaction of the ethane molecule by O(3P) atoms plays a minor role. Dissociation of the hydrocarbon through quenching collisions of the nitrogen metastable states are of great importance for a low oxygen concentration value. Also, the oxidation of ethane by O(1D) cannot be neglected at high oxygen concentration. The most probable exit channel for N2 states quenching collisions by ethane is the production of ethene and hydrogen molecules. Afterwards C2H4 should be dissociated to produce H and H2. As previously suggested from the study of the OH density time evolution in relative value, the recombination of H and O atoms appears as a main process for the production of OH in transient low temperature plasmas generated in atmospheric gases at high pressure. Another important reaction is the reduction of the HO2 radical by O, this radical coming from the addition of H on the oxygen molecule. H atoms come from numerous kinetic processes, amongst which is the dissociation of ethene.

  1. Measuring gravity currents in the Chicago River, Chicago, Illinois

    USGS Publications Warehouse

    Oberg, K.A.; Czuba, J.A.; Johnson, K.K.

    2008-01-01

    Recent studies of the Chicago River have determined that gravity currents are responsible for persistent bidirectional flows that have been observed in the river. A gravity current is the flow of one fluid within another caused by a density difference between the fluids. These studies demonstrated how acoustic Doppler current profilers (ADCP) can be used to detect and characterize gravity currents in the field. In order to better understand the formation and evolution of these gravity currents, the U.S. Geological Survey (USGS) has installed ADCPs and other instruments to continuously measure gravity currents in the Chicago River and the North Branch Chicago River. These instruments include stage sensors, thermistor strings, and both upward-looking and horizontal ADCPs. Data loggers and computers installed at gaging stations along the river are used to collect data from these instruments and transmit them to USGS offices. ?? 2008 IEEE.

  2. Electric discharge during electrosurgery.

    PubMed

    Shashurin, Alexey; Scott, David; Zhuang, Taisen; Canady, Jerome; Beilis, Isak I; Keidar, Michael

    2015-01-01

    Electric discharge utilized for electrosurgery is studied by means of a recently developed method for the diagnostics of small-size atmospheric plasma objects based on Rayleigh scattering of microwaves on the plasma volume. Evolution of the plasma parameters in the near-electrode sheaths and in the positive column is measured and analyzed. It is found that the electrosurgical system produces a glow discharge of alternating current with strongly contracted positive column with current densities reaching 10(3) A/cm(2). The plasma electron density and electrical conductivities in the channel were found be 10(16) cm(-3) and (1-2) Ohm(-1) cm(-1), respectively. The discharge interrupts every instance when the discharge-driving AC voltage crosses zero and re-ignites again every next half-wave at the moment when the instant voltage exceeds the breakdown threshold. PMID:25880721

  3. Capacitor discharge pulse analysis.

    SciTech Connect

    Baker, Michael Sean; Griffiths, Stewart K.; Tanner, Danelle Mary

    2013-08-01

    Capacitors used in firing sets and other high discharge current applications are discharge tested to verify performance of the capacitor against the application requirements. Parameters such as capacitance, inductance, rise time, pulse width, peak current and current reversal must be verified to ensure that the capacitor will meet the application needs. This report summarizes an analysis performed on the discharge current data to extract these parameters by fitting a second-order system model to the discharge data and using this fit to determine the resulting performance metrics. Details of the theory and implementation are presented. Using the best-fit second-order system model to extract these metrics results in less sensitivity to noise in the measured data and allows for direct extraction of the total series resistance, inductance, and capacitance.

  4. Ground-water discharge determined from measurements of evapotranspiration, other available hydrologic components, and shallow water-level changes, Oasis Valley, Nye County, Nevada

    USGS Publications Warehouse

    Reiner, S.R.; Laczniak, R.J.; DeMeo, G.A.; Smith, Jody L.; Elliott, P.E.; Nylund, W.E.; Fridrich, C.J.

    2002-01-01

    component of 0.5 foot, is estimated to be about 6,000 acre-feet. Annual subsurface outflow from Oasis Valley into the Amargosa Desert is estimated to be between 30 and 130 acre-feet. Estimates of total annual ground-water withdrawal from Oasis Valley by municipal and non-municipal users in 1996 and 1999 are 440 acre-feet and 210 acre-feet, respectively. Based on these values, natural annual ground-water discharge from Oasis Valley is about 6,100 acre-feet. Total annual discharge was 6,500 acre-ft in 1996 and 6,300 acre-ft in 1999. This quantity of natural ground-water discharge from Oasis Valley exceeds the previous estimate made in 1962 by a factor of about 2.5. Water levels were measured in Oasis Valley to gain additional insight into the ET process. In shallow wells, water levels showed annual fluctuations as large as 7 feet and daily fluctuations as large as 0.2 foot. These fluctuations may be attributed to water loss associated with evapotranspiration. In shallow wells affected by ET, annual minimum depths to water generally occurred in winter or early spring shortly after daily ET reached minimum rates. Annual maximum depths to water generally occurred in late summer or fall shortly after daily ET reached maximum rates. The magnitude of daily water-level fluctuations generally increased as ET increased and decreased as depth to water increased.

  5. Off-line efficiency measurements of the microwave discharge source (MIDAS) at the Laboratorio Nazionale del Sud

    NASA Astrophysics Data System (ADS)

    Gammino, S.; Ciavola, G.; Celona, L.; Torrisi, L.; Castro, M.; Chines, F.; Marletta, S.; Messina, E.; Qin, J.; Wang, Z.

    1998-02-01

    The aim of the EXCYT project at the Laboratorio Nazionale del Sud (LNS) is the production of radioactive beams, and for this we need to carry out the ionization of recoils produced in a target with as high an efficiency as possible. In order to obtain efficient positive ionization the microwave discharge ion source (MIDAS) has been designed to be followed by a charge exchange canal. A prototype of this source has been designed, built, and tested at the LNS and a description of this source is presented in this article along with the preliminary results and a design of the final version.

  6. FAST TRACK COMMUNICATION: The electrical asymmetry effect in capacitively coupled radio frequency discharges - measurements of dc self bias, ion energy and ion flux

    NASA Astrophysics Data System (ADS)

    Schulze, J.; Schüngel, E.; Czarnetzki, U.

    2009-05-01

    The recently theoretically predicted electrical asymmetry effect (EAE) (Heil et al 2008 IEEE Trans. Plasma Sci. 36 1404, Heil et al 2008 J. Phys. D: Appl. Phys. 41 165202, Czarnetzki et al 2009 J. Phys.: Conf. Ser. at press) in capacitively coupled radio frequency (CCRF) discharges and the related separate control of ion energy and flux via the EAE (Czarnetzki et al 2009 J. Phys.: Conf. Ser. at press, Donkó et al 2008 J. Phys. D: Appl. Phys. 42 025205) are tested experimentally for the first time. A geometrically symmetric CCRF discharge (equal electrode surface areas) operated at 13.56 and 27.12 MHz with variable phase angle between the harmonics is operated in argon at different pressures. The dc self bias, the energy as well as the flux of ions at the grounded electrode, and the space and phase resolved optical emission are measured. The results verify the predictions of models and simulations: via the EAE a dc self bias is generated as an almost linear function of the phase. This variable dc self bias allows separate control of ion energy and flux in an almost ideal way under various discharge conditions.

  7. A straightforward method for Vacuum-Ultraviolet flux measurements: The case of the hydrogen discharge lamp and implications for solid-phase actinometry

    SciTech Connect

    Fulvio, D. E-mail: dfu@oact.inaf.it; Brieva, A. C.; Jäger, C.; Cuylle, S. H.; Linnartz, H.; Henning, T.

    2014-07-07

    Vacuum-Ultraviolet (VUV) radiation is responsible for the photo-processing of simple and complex molecules in several terrestrial and extraterrestrial environments. In the laboratory such radiation is commonly simulated by inexpensive and easy-to-use microwave-powered hydrogen discharge lamps. However, VUV flux measurements are not trivial and the methods/devices typically used for this purpose, mainly actinometry and calibrated VUV silicon photodiodes, are not very accurate or expensive and lack of general suitability to experimental setups. Here, we present a straightforward method for measuring the VUV photon flux based on the photoelectric effect and using a gold photodetector. This method is easily applicable to most experimental setups, bypasses the major problems of the other methods, and provides reliable flux measurements. As a case study, the method is applied to a microwave-powered hydrogen discharge lamp. In addition, the comparison of these flux measurements to those obtained by O{sub 2} actinometry experiments allow us to estimate the quantum yield (QY) values QY{sub 122} = 0.44 ± 0.16 and QY{sub 160} = 0.87 ± 0.30 for solid-phase O{sub 2} actinometry.

  8. Shoulder surgery - discharge

    MedlinePlus

    SLAP repair - discharge; Acromioplasty - discharge; Bankart - discharge; Shoulder repair - discharge; Shoulder arthroscopy - discharge ... You had shoulder surgery to repair the tissues inside or around your shoulder joint. The surgeon may have used a tiny ...

  9. Estimating contaminant mass discharge: A field comparison of the multilevel point measurement and the integral pumping investigation approaches and their uncertainties

    NASA Astrophysics Data System (ADS)

    Béland-Pelletier, Caroline; Fraser, Michelle; Barker, Jim; Ptak, Thomas

    2011-03-01

    In this field study, two approaches to assess contaminant mass discharge were compared: the sampling of multilevel wells (MLS) and the integral groundwater investigation (or integral pumping test, IPT) that makes use of the concentration-time series obtained from pumping wells. The MLS approached used concentrations, hydraulic conductivity and gradient rather than direct chemical flux measurements, while the IPT made use of a simplified analytical inversion. The two approaches were applied at a control plane located approximately 40 m downgradient of a gasoline source at Canadian Forces Base Borden, Ontario, Canada. The methods yielded similar estimates of the mass discharging across the control plane. The sources of uncertainties in the mass discharge in each approach were evaluated, including the uncertainties inherent in the underlying assumptions and procedures. The maximum uncertainty of the MLS method was about 67%, and about 28% for the IPT method in this specific field situation. For the MLS method, the largest relative uncertainty (62%) was attributed to the limited sampling density (0.63 points/m 2), through a novel comparison with a denser sampling grid nearby. A five-fold increase of the sampling grid density would have been required to reduce the overall relative uncertainty for the MLS method to about the same level as that for the IPT method. Uncertainty in the complete coverage of the control plane provided the largest relative uncertainty (37%) in the IPT method. While MLS or IPT methods to assess contaminant mass discharge are attractive assessment tools, the large relative uncertainty in either method found for this reasonable well monitored and simple aquifer suggests that results in more complex plumes in more heterogeneous aquifers should be viewed with caution.

  10. Total colectomy or proctocolectomy - discharge

    MedlinePlus

    ... colectomy or proctolectomy -discharge; Restorative proctocolectomy - discharge; Ileal-anal resection - discharge; Ileal-anal pouch - discharge; J-pouch - discharge; S-pouch - discharge; Pelvic ...

  11. Measurements of discharge, gain or loss in flow, and chemical quality of the Poplar and Redwater Rivers, northeastern Montana, October 24-25, 1979

    USGS Publications Warehouse

    Dodge, Kent A.; Levings, Gary W.

    1980-01-01

    Discharge, specific conductance, and water temperature were measured at 37 sites on the Poplar and Redwater Rivers in northeastern Montana on October 24-25, 1979, to provide data on the interaction between surface-water and groundwater systems. Streamflow gains or losses were computed for those stream reaches not significantly affected by irrigation. Water samples were collected at 17 of the sites for detailed chemical-quality analysis. The tabulated data provide an areally broad data base of concurrent base-flow conditions. (USGS)

  12. Note: Measuring breakdown characteristics during the hot re-ignition of high intensity discharge lamps using high frequency alternating current voltage.

    PubMed

    van den Bos, R A J M; Sobota, A; Manders, F; Kroesen, G M W

    2013-04-01

    To investigate the cold and hot re-ignition properties of High Intensity Discharge (HID) lamps in more detail an automated setup was designed in such a way that HID lamps of various sizes and under different background pressures can be tested. The HID lamps are ignited with a ramped sinusoidal voltage signal with frequencies between 60 and 220 kHz and with amplitude up to 7.5 kV. Some initial results of voltage and current measurements on a commercially available HID lamp during hot and cold re-ignition are presented. PMID:23635237

  13. Non-intrusive measurement techniques for hydroelectric applicants

    SciTech Connect

    Birch, R.; Lemon, D.

    1995-12-31

    Non-intrusive acoustic methods for measuring flows, originally developed for oceanographic applications, are being used in and around hydroelectric dams. The acoustic methods can be categorized as either back-scattering or forward-scattering. The first, using the back-scattered signal, measures the Doppler shift of the returning echo to determine the along-beam component of flow. These instruments are generally called Acoustic Doppler Current Profilers (ADCP). Three beam solutions allow computation of the velocity components. Time gating the return provides a velocity profile with bin segments as small as 0.25 in. In areas of strong magnetic deviation, often the case beside large dams, a gyrocompass can be used to provide directional orientation. The velocity data can also be used to quickly compute river or channel discharge. Typical applications and several case studies are presented. The second acoustic technique is based on a forward-scattering phenomenon known as scintillation. This technique has been used on the Fraser River to monitor flows, and properties of the signal have recently been correlated with the biomass of upstream-migrating salmon. Acoustic scintillation flow measurements are well suited to applications with limited space in the along-flow direction. Applications to hydroelectric dams include turbine intake flow measurements, and a system has been developed to measure flow along fish diversion screens.

  14. Measurements of the volt-ampere characteristics and the breakdown voltages of direct-current helium and hydrogen discharges in microgaps

    SciTech Connect

    Klas, M.; Matejčik, Š.; Radjenović, B.; Radmilović-Radjenović, M.

    2014-10-15

    The discharge phenomena for micro meter gap sizes include many interesting problems from engineering and physical perspectives. In this paper, the authors deal with the experimental and theoretical results of the breakdown voltage and current-voltage characteristics of the direct-current helium and hydrogen discharges. The measurements were performed at a constant pressure of around one atmosphere, while varying the gap size between two parallel plane tungsten electrodes between 1 μm and 100 μm. From the measured breakdown voltage curves, the effective yields and the ionization coefficients were derived for both gases. Present data for the ionization coefficients correlate with the data obtained for the breakdown voltage curves measured for fixed 100 μm interelectrode separation. The current-voltage characteristics were plotted for the various gap sizes illustrating the role of the field emission effects in the microgaps. Based on the Fowler-Nordheim theory, the enhancement factors were determined. The gap spacing dependence of the field emission current can be explained by the introduction of two ideas, the first being a space charge effect by emitted electrons, and the second a change in the breakdown mechanism. Experimental results, presented here, demonstrate that Townsend phenomenology breaks down when field emission becomes the key mechanism affecting the breakdown and deforming the left hand side of the breakdown voltage curves.

  15. Measurements of the volt-ampere characteristics and the breakdown voltages of direct-current helium and hydrogen discharges in microgaps

    NASA Astrophysics Data System (ADS)

    Klas, M.; Matejčik, Š.; Radjenović, B.; Radmilović-Radjenović, M.

    2014-10-01

    The discharge phenomena for micro meter gap sizes include many interesting problems from engineering and physical perspectives. In this paper, the authors deal with the experimental and theoretical results of the breakdown voltage and current-voltage characteristics of the direct-current helium and hydrogen discharges. The measurements were performed at a constant pressure of around one atmosphere, while varying the gap size between two parallel plane tungsten electrodes between 1 μm and 100 μm. From the measured breakdown voltage curves, the effective yields and the ionization coefficients were derived for both gases. Present data for the ionization coefficients correlate with the data obtained for the breakdown voltage curves measured for fixed 100 μm interelectrode separation. The current-voltage characteristics were plotted for the various gap sizes illustrating the role of the field emission effects in the microgaps. Based on the Fowler-Nordheim theory, the enhancement factors were determined. The gap spacing dependence of the field emission current can be explained by the introduction of two ideas, the first being a space charge effect by emitted electrons, and the second a change in the breakdown mechanism. Experimental results, presented here, demonstrate that Townsend phenomenology breaks down when field emission becomes the key mechanism affecting the breakdown and deforming the left hand side of the breakdown voltage curves.

  16. Depth-dependent permeability of hydrothermal discharge zones: measurements through tidal modulation and implications for mid-ocean ridge heat budgets

    NASA Astrophysics Data System (ADS)

    Barreyre, T.; Crone, T. J.; Olive, J. A. L.

    2015-12-01

    The efficiency of hydrothermal circulation as a heat and mass exchanger is strongly modulated by the permeability structure of newly formed oceanic crust, which is known to vary spatially and temporally. Here we use the modulation of discharge temperatures by oscillatory tidal loading to estimate permeability vs. depth profiles beneath hydrothermal discharge zones at three basalt-hosted hydrothermal fields. Phase lags between fluctuations in discharge temperature and seafloor tidal loading have previously been inverted for the permeability of the underlying discharge zone using the poroelastic modulation model of Jupp and Schulz [2004]. This has yielded a wide range of permeability estimates ranging from 10-13­-10-9 m2. Here we extend the model to a stratified medium comprising a top layer (2A) of permeability k2A overlying a bottom layer (2B) of permeability k2B. We apply it to three basalt-hosted hydrothermal fields on a slow- (Lucky Strike), intermediate- (Main Endeavour Field), and fast-spreading (East Pacific Rise, EPR-9ºN) ridge, where stratification is well known from seismic studies. We estimate a layer 2A permeability of ~10-10 m2 at Lucky Strike, in sharp contrast with EPR-9ºN, where k2A ~ 10-13 m2. At the Main Endeavour field, two different sites located above different distinct discharge zones (as indicated by magnetic studies) yield a high and a low permeability. The permeability of layer 2B is not as well constrained as that of layer 2A, with possible values ranging from 10-14-10-12 m2. We note, however, that the variability in measured phase lags across hydrothermal fields is compatible with a uniform layer 2B permeability of ~10-13 m2. Using theoretical scalings for high-Rayleigh porous convection, we demonstrate that the permeability of layer 2B sets the "effective permeability" of the entire convective system, and therefore the efficiency of heat extraction through young oceanic crust. A uniform layer 2B permeability would thus reconcile the

  17. The effects of riverine discharge on temperature, salinity, suspended sediment and chlorophyll a in a Mississippi delta estuary measured using a flow-through system

    NASA Astrophysics Data System (ADS)

    Lane, Robert R.; Day, John W., Jr.; Marx, Brian D.; Reyes, Enrique; Hyfield, Emily; Day, Jason N.

    2007-08-01

    The impact of diverted Mississippi River water on temperature, salinity, total suspended sediment (TSS) and chlorophyll a were monitored in the Breton Sound estuary from September 7, 2000, to August 28, 2002. Twenty-seven transects were carried out using a flow-through system to continuously measure temperature, salinity, turbidity and fluorescence, and discrete water samples were taken at 16 locations for calibration. Discharge from the river diversion structure ranged from 0 to 213 m 3/s, with several large pulses of water released during the spring of 2001 and 2002. There was a strong seasonal temperature signal in the estuary, with summer highs of >30 °C and winter lows of <12 °C. Incoming river water was usually cooler than estuarine waters, with temperatures as low as 6 °C, but generally equilibrated to the rest of the estuary within several kilometers. Salinity in the upper estuary was fresh throughout the study, and increased up to 14 and 30 PSU along Western and Eastern routes, respectfully, with distance from the diversion. Discharge from the river diversion greatly affected salinity, with the large spring pulses often causing the entire estuary to become fresh for a short period of time (<1 month). There was also a temporal lag of about two weeks between discharge and salinity in the lower estuary. River water entering the estuary had TSS concentrations ranging from 40 to 252 mg/L, with an average of 118 mg/L. Sediment from the river diversion reached about 10-15 km into the estuary during spring pulses. There were highly fluctuating TSS concentrations at the Gulf end of the estuary during winter and spring, due to wind resuspension. Chlorophyll a concentrations were highest in mid-estuary during summer and fall low discharge, and lowest during winter and spring high discharge. Chlorophyll a levels were generally less than 10 μg/L in the upper estuary, with concentrations rising in the mid-estuary generally to 20-30 μg/L during late summer and fall

  18. Electrostatic discharge test apparatus

    NASA Technical Reports Server (NTRS)

    Smith, William Conrad (Inventor)

    1988-01-01

    Electrostatic discharge properties of materials are quantitatively measured and ranked. Samples are rotated on a turntable beneath selectable, co-available electrostatic chargers, one being a corona charging element and the other a sample-engaging triboelectric charging element. Samples then pass under a voltage meter to measure the amount of residual charge on the samples. After charging is discontinued, measurements are continued to record the charge decay history over time.

  19. Electrostatic discharge test apparatus

    NASA Technical Reports Server (NTRS)

    Smith, William C. (Inventor)

    1989-01-01

    Electrostatic discharge properties of materials are quantitatively measured and ranked. Samples (20) are rotated on a turntable (15) beneath selectable, co-available electrostatic chargers (30/40), one being a corona charging element (30) and the other a sample-engaging triboelectric charging element (40). They then pass under a voltage meter (25) to measure the amount of residual charge on the samples (20). After charging is discontinued, measurements are continued to record the charge decay history over time.

  20. Delayed discharge.

    PubMed

    Allen, Daniel

    2016-07-01

    Essential facts Delays in discharging older peo ple from hospital cost the NHS £820 million a year, according to a report from the National Audit Office (NAO). Last year in acute hospitals, 1.15 million bed days were lost to delayed transfers of care, an increase of 31% since 2013. The NAO says rising demand for NHS services is compounded by reduced local authority spending on adult social care - down by 10% since 2009-10. PMID:27380673

  1. LDV measurements of the velocity field on the inlet section of a pumped storage equipped with a symmetrical suction elbow for variable discharge values

    NASA Astrophysics Data System (ADS)

    ǎghici, I., Dr; Muntean, S.; Bosioc, A. I.; Anton, L. E.

    2014-03-01

    The storage pumps are equipped with various types of inlet casings. The flow nonuniformity is generated by the suction elbows being ingested by the impeller leading to unsteady phenomena and worse cavitational behaviour. A symmetrical suction elbow model corresponding to the double flux storage pump was manufactured and installed on the test rig in order to assess the flow field at the pump inlet. The experimental investigations are performed for 9 discharge values from 0.5 to 1.3 of nominal discharge. LDV measurements are performed on the annular section of the pump inlet in order to quantify the flow non-uniformity generated by the symmetrical suction elbow. Both axial and circumferential velocity components are simultaneously measured on the half plane (180°) of the annular inlet section along to 19 survey axis with 62 points on each. The flow field on the next half plane is determined tacking into account the symmetry. As a result, the flow map on the pump inlet annular section is reconstructed revealing a significant variation of the circumferential velocity component. The absolute flow angle is computed showing a significant variation of ±38°.

  2. Measurements of ion temperature and plasma hydrogenic composition by collective Thomson scattering in neutral beam heated discharges at TEXTOR

    NASA Astrophysics Data System (ADS)

    Stejner, M.; Salewski, M.; Korsholm, S. B.; Bindslev, H.; Delabie, E.; Leipold, F.; Meo, F.; Michelsen, P. K.; Moseev, D.; Nielsen, S. K.; Bürger, A.; de Baar, M.; the TEXTOR Team

    2013-08-01

    A method is developed to perform plasma composition and ion temperature measurements across the plasma minor radius in TEXTOR based on ion cyclotron structures in collective Thomson scattering spectra. By gradually moving the scattering volume, we obtain measurements across the outer midplane of the plasma. Results for the ion temperature are compared with ion temperatures measured by active charge-exchange recombination spectroscopy.

  3. Hysterectomy - vaginal - discharge

    MedlinePlus

    Vaginal hysterectomy - discharge; Laparoscopically assisted vaginal hysterectomy - discharge; LAVH - discharge ... you were in the hospital, you had a vaginal hysterectomy. Your surgeon made a cut in your ...

  4. Hysterectomy - vaginal - discharge

    MedlinePlus

    Vaginal hysterectomy - discharge; Laparoscopically assisted vaginal hysterectomy - discharge; LAVH - discharge ... were in the hospital, you had a vaginal hysterectomy. Your surgeon made a cut in your vagina. ...

  5. Electron heating enhancement due to plasma series resonance in a capacitively coupled RF discharge: Electrical modeling and comparison to experimental measurements

    NASA Astrophysics Data System (ADS)

    Cao, Minglu; Lu, Yijia; Cheng, Jia; Ji, Linhong

    2016-09-01

    The electron heating enhancement due to the self-excitation of the plasma series resonance in capacitively coupled plasmas is revisited by a combination of an equivalent circuit model and experiments. To improve the model accuracy, measured voltage waveforms at the powered electrode are used instead of prescribing a sinusoidal voltage supply in series with a bias capacitance. The results calculated from the electrical model are consistent with the experimental measurements performed by a Langmuir probe with verification of a microwave interferometer, at pressures of 0.2 and 0.3 Torr. High harmonics occurring in the discharge currents agree with observations in previous research. The nonlinear plasma series resonance effect is found to have a notable contribution to both ohmic and stochastic heating evaluated by the electron heating efficiencies.

  6. Effect of gold mining activities on water turbidity and river sediment discharge: comparison of two nearby river basin in French Guiana, using remote sensing and field measurements data

    NASA Astrophysics Data System (ADS)

    Marjorie, Gallay; Jean-Michel, Martinez; Alain, Laraque; Max, Sarrazin; Jean-Claude, Doudou; Antoine, Gardel; Vincent, Vantrepotte; Franck, Chow-Toun

    2016-04-01

    The Maroni and Oyapock rivers are two nearby basin in French Guiana, South America. The Maroni river drains a basin of 66 000 km² between French Guiana and Surinam. The Oyapock river basin covers 28 000 km² over French Guiana and Brazil. The Both over the Guyana shield presenting very lowest erosion rates. For both rivers, Suspended Sediment Concentration and remote sensing reflectance have been determined, during 3 fields sampling campaigns, using TriOs RAMSES radiometers operating in the 350-900 nm spectral range. Field data are compared with MODIS spaceborne sensors onboard calibration Terra and Aqua satellites. For the first time over the Maroni river, we show that it is possible to monitored from space both Surface Suspended Sediment Concentration (SSSC) and the Turbidity (R²=0,81), making possible to evaluate water quality long term. Combining fields and satellite derived SSSC measurements, we detected an increase of median SSSC (20 to 30 mg/l)and sediment budget in the Maroni river and a stability for the Oyapock river (10 mg/l), since 2000. Almost, relationship between SSSC and river water discharge was investigated for both rivers and for the 2000-2015 period. We show that SSSC and Maroni river discharge present decreasing correlation over the period of study. For the Oyapock River, SSSC and river discharge show good relationship over the period of study. Analysis of land-use change in the Maroni catchment showed an important increase of areas affected by gold mining which explain the observed modification of the Maroni River Suspended Sediment budget.

  7. Considering sampling strategy and cross-section complexity for estimating the uncertainty of discharge measurements using the velocity-area method

    NASA Astrophysics Data System (ADS)

    Despax, Aurélien; Perret, Christian; Garçon, Rémy; Hauet, Alexandre; Belleville, Arnaud; Le Coz, Jérôme; Favre, Anne-Catherine

    2016-02-01

    Streamflow time series provide baseline data for many hydrological investigations. Errors in the data mainly occur through uncertainty in gauging (measurement uncertainty) and uncertainty in the determination of the stage-discharge relationship based on gaugings (rating curve uncertainty). As the velocity-area method is the measurement technique typically used for gaugings, it is fundamental to estimate its level of uncertainty. Different methods are available in the literature (ISO 748, Q + , IVE), all with their own limitations and drawbacks. Among the terms forming the combined relative uncertainty in measured discharge, the uncertainty component relating to the limited number of verticals often includes a large part of the relative uncertainty. It should therefore be estimated carefully. In ISO 748 standard, proposed values of this uncertainty component only depend on the number of verticals without considering their distribution with respect to the depth and velocity cross-sectional profiles. The Q + method is sensitive to a user-defined parameter while it is questionable whether the IVE method is applicable to stream-gaugings performed with a limited number of verticals. To address the limitations of existing methods, this paper presents a new methodology, called FLow Analog UnceRtainty Estimation (FLAURE), to estimate the uncertainty component relating to the limited number of verticals. High-resolution reference gaugings (with 31 and more verticals) are used to assess the uncertainty component through a statistical analysis. Instead of subsampling purely randomly the verticals of these reference stream-gaugings, a subsampling method is developed in a way that mimicks the behavior of a hydrometric technician. A sampling quality index (SQI) is suggested and appears to be a more explanatory variable than the number of verticals. This index takes into account the spacing between verticals and the variation of unit flow between two verticals. To compute the

  8. Pediatric heart surgery - discharge

    MedlinePlus

    ... discharge; Heart valve surgery - children - discharge; Heart surgery - pediatric - discharge; Heart transplant - pediatric - discharge ... Keane JF, Lock JE, Fyler DC, eds. Nadas' Pediatric Cardiology . 2nd ed. St. Louis, MO; WB Saunders; ...

  9. Heart attack - discharge

    MedlinePlus

    Myocardial infarction - discharge; MI - discharge; Coronary event - discharge; Infarct - discharge ... of patients with unstable angina/non-ST-Elevation myocardial infarction: a report of the American College of Cardiology/ ...

  10. Gastroesophageal reflux - discharge

    MedlinePlus

    Peptic esophagitis - discharge; Reflux esophagitis - discharge; GERD - discharge; Heartburn - chronic - discharge ... You have gastroesophageal reflux disease (GERD). This is a condition in which food or liquid travels backwards from the stomach to the ...

  11. Refractive corneal surgery - discharge

    MedlinePlus

    Nearsightedness surgery - discharge; Refractive surgery - discharge; LASIK - discharge; PRK - discharge ... You had refractive corneal surgery to help improve your vision. This surgery uses a laser to reshape your cornea. It corrects ...

  12. Tubal ligation - discharge

    MedlinePlus

    Sterilization surgery - female - discharge; Tubal sterilization - discharge; Tube tying - discharge; Tying the tubes - discharge ... You had tubal ligation (or tying the tubes) surgery to close your fallopian tubes. These tubes connect the ovaries to the uterus. ...

  13. Spectroscopic measurements of the electron number density, electron temperature and OH(A) rotational distribution in a liquid electrode dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Krähling, Tobias; Geisler, Sebastian; Okruss, Michael; Florek, Stefan; Franzke, Joachim

    2015-12-01

    The electron temperature and number density as well as the OH(A) rotational distribution of a discharge with flowing liquid electrode and dielectric barrier coupling (a liquid electrode dielectric barrier discharge, LE-DBD) were investigated by means of optical emission spectroscopy. By using the Stark broadening of three Strontium lines, the electron number density Ne and the lower bound of the electron temperature Te can be simultaneously measured. The values obtained were Ne = (0.8 - 1.6) × 1016 cm- 3 and Te > 1.1 eV, respectively. The OH(A) rotational distribution deviates from equilibrium and can be described by a superposition of two Boltzmann distributions with T1 = (3230 ± 90) K for K ' ≤ 15 and T2 = (7300 ± 300) K for K ' ≥ 16. Consideration of the formation mechanisms of OH(A) and reaction rates suggests that the dissociative recombination of H2O+ and H3O+ is responsible for the higher rotational state distribution, where these ions can only be produced in the LE-DBD through an electrospray-like process.

  14. Assessing the variability of glacier lake bathymetries and potential peak discharge based on large-scale measurements in the Cordillera Blanca, Peru

    NASA Astrophysics Data System (ADS)

    Cochachin, Alejo; Huggel, Christian; Salazar, Cesar; Haeberli, Wilfried; Frey, Holger

    2015-04-01

    Over timescales of hundreds to thousands of years ice masses in mountains produced erosion in bedrock and subglacial sediment, including the formation of overdeepenings and large moraine dams that now serve as basins for glacial lakes. Satellite based studies found a total of 8355 glacial lakes in Peru, whereof 830 lakes were observed in the Cordillera Blanca. Some of them have caused major disasters due to glacial lake outburst floods in the past decades. On the other hand, in view of shrinking glaciers, changing water resources, and formation of new lakes, glacial lakes could have a function as water reservoirs in the future. Here we present unprecedented bathymetric studies of 124 glacial lakes in the Cordillera Blanca, Huallanca, Huayhuash and Raura in the regions of Ancash, Huanuco and Lima. Measurements were carried out using a boat equipped with GPS, a total station and an echo sounder to measure the depth of the lakes. Autocad Civil 3D Land and ArcGIS were used to process the data and generate digital topographies of the lake bathymetries, and analyze parameters such as lake area, length and width, and depth and volume. Based on that, we calculated empirical equations for mean depth as related to (1) area, (2) maximum length, and (3) maximum width. We then applied these three equations to all 830 glacial lakes of the Cordillera Blanca to estimate their volumes. Eventually we used three relations from the literature to assess the peak discharge of potential lake outburst floods, based on lake volumes, resulting in 3 x 3 peak discharge estimates. In terms of lake topography and geomorphology results indicate that the maximum depth is located in the center part for bedrock lakes, and in the back part for lakes in moraine material. Best correlations are found for mean depth and maximum width, however, all three empirical relations show a large spread, reflecting the wide range of natural lake bathymetries. Volumes of the 124 lakes with bathymetries amount to 0

  15. Reducing harmful emissions discharged into the atmosphere from operating boilers by applying a combination of low-cost technological measures

    NASA Astrophysics Data System (ADS)

    Roslyakov, P. V.; Ionkin, I. L.; Pleshanov, K. A.

    2010-12-01

    The operational methods for suppressing nitrogen oxide emissions widely used in gas-and-oil-fired boilers are described. Information is given on implementing integrated operational measures in BKZ-75-39GM and TGM-96B boilers.

  16. ADCP observations about the mean stratification and the vertical structure of tidal and inertial currents in the northern Adriatic

    NASA Astrophysics Data System (ADS)

    Fuda, J.-L.; Millot, C.

    2003-04-01

    Mounted on the GEOSTAR benthic observatory (Beranzoli et al., 2000) which was deployed in August 1998 at about 42 m in the northern Adriatic for test purposes, a 300-kHz ADCP was operated during 18 days with an hourly sampling rate. The reduced cell size of 80 cm allowed to study finely i) the temporal variation of the mean stratification, ii) the vertical structure of tidal currents and iii) an energetic few-day episode of inertial oscillations. Even though no thermistor string was available to monitor the stratification's evolution, the maximum magnitude of the current shear was found to be a relevant indicator of the pycnocline's depth, as confirmed by ship-handled CTD profiles performed just before and after the experiment. From the depth evolution of the shear maximum, it was possible to detect a sudden deepening of the pycnocline (from about 14 m down to about 30 m), consistently with simultaneous temperature and salinity increases recorded by an observatory-mounted SBE16 CTD. Such a deepening might be attributed to the advection of a neighbouring thicker mixed layer, to an intense vertical mixing due to sea roughness or, more probably, to a downwelling phenomenon. Indeed, it was associated with south-easterly winds that prevailed in the northern Adriatic and with downward vertical velocities (1-2 cm/s) that were sampled over the whole depth during the pycnocline's deepening. Rotary spectral analysis and band-pass filtering at all depths in the inertial, diurnal and semi-diurnal frequency bands revealed the complex vertical structure of the related currents. This is particularly striking for the diurnal components whose energy is confined in a few-meter surface layer, contrary to the energy of the semidiurnal components which is distributed over the whole water column. Concerning the former (K1 mainly), the tidal harmonic analysis (Foreman, 1978) evidences a clockwise polarisation of the currents and a roughly constant orientation of the related ellipses

  17. Note: An approach to measurement of low frequency oscillation amplitude of discharge current of in-orbit Hall thruster.

    PubMed

    Han, Liang; Ding, Yongjie; Wei, Liqiu; Yu, Daren

    2014-06-01

    This paper provides a method to measure the amplitude of low frequency oscillation under the on-track working condition, and realizes the sampling by means of adding the circuit design of sampling, low pass filtering by 3 dB at 48.2 kHz, detection and integrating in the filtering unit. The experimental results prove that the measuring device of merely 0.8 g can quantitatively reflect the amplitude of low frequency oscillation in Hall thruster and the maximum deviation of experiment data and theory data is 10% FS. PMID:24985877

  18. Spectroscopic measurements of the parameters of the helium plasma jets generated in the plasma focus discharge at the PF-3 facility

    NASA Astrophysics Data System (ADS)

    Ananyev, S. S.; Dan'ko, S. A.; Myalton, V. V.; Zhuzhunashvili, A. I.; Kalinin, Yu. G.; Krauz, V. I.; Ladygina, M. S.; Marchenko, A. K.

    2016-03-01

    The spectroscopic technique used to measure the parameters of the plasma jets generated in the plasma focus discharge and those of the plasma of the immobile gas through which these jets propagate is described. The time evolution of the intensities and shapes of spectral lines in experiments carried out with helium at the PF-3 facility was studied by means of electron-optical streak cameras. The plasma electron temperature, T ≈ 4-5 eV, was determined from the intensity ratio of two spectral lines, one of which (λ1 = 5876 Å) belongs to neutral helium, while the other (λ2 = 4686 Å), to hydrogen-like helium ions. The plasma density at different time instants was determined from the Stark broadening of these lines in the electric fields of different nature. The plasma density is found to vary from 4 × 1014 to 2 × 1017 cm-3.

  19. Thrust Measurement of Dielectric Barrier Discharge (DBD) Plasma Actuators: New Anti-Thrust Hypothesis, Frequency Sweeps Methodology, Humidity and Enclosure Effects

    NASA Technical Reports Server (NTRS)

    Ashpis, David E.; Laun, Matthew C.

    2014-01-01

    We discuss thrust measurements of Dielectric Barrier Discharge (DBD) plasma actuators devices used for aerodynamic active flow control. After a review of our experience with conventional thrust measurement and significant non-repeatability of the results, we devised a suspended actuator test setup, and now present a methodology of thrust measurements with decreased uncertainty. The methodology consists of frequency scans at constant voltages. The procedure consists of increasing the frequency in a step-wise fashion from several Hz to the maximum frequency of several kHz, followed by frequency decrease back down to the start frequency of several Hz. This sequence is performed first at the highest voltage of interest, then repeated at lower voltages. The data in the descending frequency direction is more consistent and selected for reporting. Sample results show strong dependence of thrust on humidity which also affects the consistency and fluctuations of the measurements. We also observed negative values of thrust, or "anti-thrust", at low frequencies between 4 Hz and up to 64 Hz. The anti-thrust is proportional to the mean-squared voltage and is frequency independent. Departures from the parabolic anti-thrust curve are correlated with appearance of visible plasma discharges. We propose the anti-thrust hypothesis. It states that the measured thrust is a sum of plasma thrust and anti-thrust, and assumes that the anti-thrust exists at all frequencies and voltages. The anti-thrust depends on actuator geometry and materials and on the test installation. It enables the separation of the plasma thrust from the measured total thrust. This approach enables more meaningful comparisons between actuators at different installations and laboratories. The dependence on test installation was validated by surrounding the actuator with a grounded large-diameter metal sleeve. Strong dependence on humidity is also shown; the thrust significantly increased with decreasing humidity, e

  20. Acoustic Measurements in a Hexamethyldisiloxane-Loaded Low-Temperature Direct Barrier Discharge (DBD) Plasma Effluent: Nozzle Cleaning

    NASA Astrophysics Data System (ADS)

    Burkert, A.; Müller, D.; Paa, W.

    2015-04-01

    Acoustic emission (AE) measurements as well as laser light scattering experiments were performed during SiO2 layer deposition. SiO2 was generated in low-temperature atmospheric plasma torches (≤500 W), which were seeded with hexamethyldisiloxane. These AE measurements can be used to detect the necessity for nozzle cleaning online. The plasma torches were used to obtain high-quality SiO2 coatings. For electrical power of less than 350 W, we observed parasitic SiO2 deposition in the burner nozzle, which decreases the nozzle aperture within several hours of operation time. No parasitic SiO2 deposition inside the burner nozzle was observed when the plasma source was operated at more than 350 W. The reduced nozzle aperture causes increased plasma velocities and acoustic noise. Especially burst-like increases of this acoustic emission were assumed to be correlated to the ejection of particles. This hypothesis could be confirmed by measurements of scattered light from a sheet of laser light at 248 nm. The obtained correlations suggest using a microphone as a low-cost monitor for the degree of parasitic deposition inside the plasma burner nozzle. The threshold for acoustic noise detection has to be chosen low enough to avoid burst-like emission of particles.

  1. Langmuir Probe Measurements Within the Discharge Channel of the 20-kW NASA-300M and NASA-300MS Hall Thrusters

    NASA Technical Reports Server (NTRS)

    Shastry, Rohit; Huang, Wensheng; Haag, Thomas W.; Kamhawi, Hani

    2013-01-01

    NASA is presently developing a high-power, high-efficiency, long-lifetime Hall thruster for the Solar Electric Propulsion Technology Demonstration Mission. In support of this task, studies have been performed on the 20-kW NASA-300M Hall thruster to aid in the overall design process. The ability to incorporate magnetic shielding into a high-power Hall thruster was also investigated with the NASA- 300MS, a modified version of the NASA-300M. The inclusion of magnetic shielding would allow the thruster to push existing state-of-the-art technology in regards to service lifetime, one of the goals of the Technology Demonstration Mission. Langmuir probe measurements were taken within the discharge channels of both thrusters in order to characterize differences at higher power levels, as well as validate ongoing modeling efforts using the axisymmetric code Hall2De. Flush-mounted Langmuir probes were also used within the channel of the NASA-300MS to verify that magnetic shielding was successfully applied. Measurements taken from 300 V, 10 kW to 600 V, 20 kW have shown plasma potentials near anode potential and electron temperatures of 4 to 12 eV at the walls near the thruster exit plane of the NASA-300MS, verifying magnetic shielding and validating the design process at this power level. Channel centerline measurements on the NASA-300M from 300 V, 10 kW to 500 V, 20 kW show the electron temperature peak at approximately 0.1 to 0.2 channel lengths upstream of the exit plane, with magnitudes increasing with discharge voltage. The acceleration profiles appear to be centered about the exit plane with a width of approximately 0.3 to 0.4 channel lengths. Channel centerline measurements on the NASA-300MS were found to be more challenging due to additional probe heating. Ionization and acceleration zones appeared to move downstream on the NASA-300MS compared to the NASA-300M, as expected based on the shift in peak radial magnetic field. Additional measurements or alternative

  2. Measurement of metastable He{sup *}(2{sup 3}S{sub 1}) density in dielectric barrier discharges with two different configurations operating at around atmospheric pressure

    SciTech Connect

    Tachibana, K.; Kishimoto, Y.; Sakai, O.

    2005-06-15

    We have measured the density of metastable He atoms in the lowest triplet state (2{sup 3}S{sub 1}) with a diode-laser absorption spectroscopic technique in atmospheric pressure plasmas produced by dielectric barrier discharge schemes. Two different types of electrode configuration are employed: one is a conventional parallel-plate system and the other is a microdischarge integrated system with stacked metal-mesh electrodes covered by insulating films. We have analyzed the pressure-broadened spectral line corresponding to the 2{sup 3}S{sub 1}{yields}2{sup 3}P{sub J} (J=0-2) transition to derive the broadening coefficient and to calibrate absolute densities. The measured density ranges from 10{sup 11} to 10{sup 12} cm{sup -3}, but the values in the mesh-type system are larger than those in the parallel-plate system by about one order of magnitude. The density, however, depends strongly on the gas flow rate, showing the influence of quenching by the Penning-ionization process with impurities. Those behaviors are consistent with the variation of the electron density estimated by millimeter-wave transmittance measurement.

  3. Measurement of metastable He*(23S1) density in dielectric barrier discharges with two different configurations operating at around atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Tachibana, K.; Kishimoto, Y.; Sakai, O.

    2005-06-01

    We have measured the density of metastable He atoms in the lowest triplet state (2S13) with a diode-laser absorption spectroscopic technique in atmospheric pressure plasmas produced by dielectric barrier discharge schemes. Two different types of electrode configuration are employed: one is a conventional parallel-plate system and the other is a microdischarge integrated system with stacked metal-mesh electrodes covered by insulating films. We have analyzed the pressure-broadened spectral line corresponding to the 2S13→2PJ3 (J=0-2) transition to derive the broadening coefficient and to calibrate absolute densities. The measured density ranges from 1011 to 1012cm-3, but the values in the mesh-type system are larger than those in the parallel-plate system by about one order of magnitude. The density, however, depends strongly on the gas flow rate, showing the influence of quenching by the Penning-ionization process with impurities. Those behaviors are consistent with the variation of the electron density estimated by millimeter-wave transmittance measurement.

  4. Time-Resolved Laser-Induced Fluorescence Measurements of Ion Velocity Distribution in the Plume of a 6 kW Hall Thruster with Unperturbed Discharge Oscillations

    NASA Astrophysics Data System (ADS)

    Durot, Christopher; Gallimore, Alec

    2014-10-01

    We present laser-induced fluorescence (LIF) measurements of the time-resolved ion velocity distribution in the plume of a 6 kW laboratory Hall thruster. To our knowledge, these are the first measurements of time-resolved ion velocity distribution on completely unperturbed Hall thruster operating conditions. To date, time-resolved LIF measurements have been made on Hall thrusters with oscillations driven or perturbed to be amenable to averaging techniques that assume a periodic oscillation. Natural Hall thruster breathing and spoke oscillations, however, are not periodic due to chaotic variations in amplitude and frequency. Although the system averages over many periods of nonperiodic oscillation, it recovers the time-resolved signal in part by assuming that a constant transfer function exists relating discharge current and LIF signal and averaging over the transfer function itself (http://dx.doi.org/10.1063/1.4856635). The assumption of a constant transfer function has been validated for a Hall thruster and the technique is now applied to a Hall thruster for the first time.

  5. Focusing and photon flux measurements of the 2.88-nm radiation at the sample plane of the soft x-ray microscope, based on capillary discharge source

    NASA Astrophysics Data System (ADS)

    Nawaz, M. Fahad; Jancarek, Alexandr; Nevrkla, Michal; Wachulak, Przemyslaw; Limpouch, Jiri; Pina, Ladislav

    2015-05-01

    Feasibility measurements leading to the development of a Soft X-ray (SXR) microscopy setup, based on capillary discharge XUV source is presented. Here the Z-pinching plasma is acting as a source of XUV radiation, emitting incoherent radiation in the "water-window" (λ = 2.3 - 4.4 nm) region of interest (natural contrast between the carbon and oxygen edges).This soft X-ray microscopy setup will realize imaging of the biological objects with high spatial resolution. The 2.88 nm radiation line is filtered out from the water-window band, and is focused by an axi-symmetric ellipsoidal mirror, coated with nickle. The focussed spot size is measured and reported. Flux measurements for the available number of photons (photons/pulse) at the sample plane has been carried out with AXUV PIN diode at the sample plane (slightly out of focus). For imaging, a fresnel zone plate lens will be used as an objective. The overall compact transmission SXR microscopy setup design is presented.

  6. Comparison of Plasma Density Measurements in ICP Discharges Using Langmuir Probe, Plasma Oscillation Probe and Interferometry Techniques

    NASA Astrophysics Data System (ADS)

    Evans, John; Zawalski, Wade; Chen, Francis

    2000-10-01

    A comparison study of the application of various probe theories, including the so-called orbital motion limited (OML) and ABR theories, in the interpretation of Langmuir probe I-V characteristics is performed. Experimental data for the comparison is obtained in an inductively coupled plasma (ICP) source over a wide range of parameters of interest to the plasma processing community. Measurements of Ni from the Hiden Electrostatic Plasma Probe (ESP) characteristics and software are compared to ``known" values of Ne obtained via microwave interferometry and the plasma oscillation probe (POP) technique, in regimes including those where the probe theories yield different results. Excellent agreement is obtained between the interferometry and POP methods at low Po, whereas POP starts to fail at Po>5 mTorr, as expected. Langmuir probe results using OML theory yield reasonable agreement for Ne<2x1011cm-3, but fail at higher Ne. Closely spaced multiple peaks in the spectra of the POP are observed in some cases at higher RF input powers, possibly due to RF modulation of the source plasma density, leading to experimental uncertainty in Ne values thus obtained. Other considerations for the applicability of the POP method will also be discussed.

  7. Using noble gases measured in spring discharge to trace hydrothermal processes in the Norris Geyser Basin, Yellowstone National Park, U.S.A.

    USGS Publications Warehouse

    Gardner, W.P.; Susong, D.D.; Solomon, D.K.; Heasler, H.P.

    2010-01-01

    Dissolved noble gas concentrations in springs are used to investigate boiling of hydrothermal water and mixing of hydrothermal and shallow cool water in the Norris Geyser Basin area. Noble gas concentrations in water are modeled for single stage and continuous steam removal. Limitations on boiling using noble gas concentrations are then used to estimate the isotopic effect of boiling on hydrothermal water, allowing the isotopic composition of the parent hydrothermal water to be determined from that measured in spring. In neutral chloride springs of the Norris Geyser Basin, steam loss since the last addition of noble gas charged water is less than 30% of the total hydrothermal discharge, which results in an isotopic shift due to boiling of ?? 2.5% ??D. Noble gas concentrations in water rapidly and predictably change in dual phase systems, making them invaluable tracers of gas-liquid interaction in hydrothermal systems. By combining traditional tracers of hydrothermal flow such as deuterium with dissolved noble gas measurements, more complex hydrothermal processes can be interpreted. ?? 2010 Elsevier B.V.

  8. Eye muscle repair - discharge

    MedlinePlus

    ... Lazy eye repair - discharge; Strabismus repair - discharge; Extraocular muscle surgery - discharge ... You or your child had eye muscle repair surgery to correct eye muscle ... term for crossed eyes is strabismus. Children most often ...

  9. Radical prostatectomy - discharge

    MedlinePlus

    ... laparoscopic prostatectomy - discharge ; RALP - discharge; Pelvic lymphadenectomy - discharge; Prostate cancer - prostatectomy ... some lymph nodes. This was done to treat prostate cancer. Your surgeon may have made an incision (cut) ...

  10. Tennis elbow surgery - discharge

    MedlinePlus

    ... epicondylitis surgery - discharge; Lateral tendinosis surgery - discharge; Lateral tennis elbow surgery - discharge ... long as you are told. This helps ensure tennis elbow will not return. You may be prescribed ...

  11. Pulsed discharge production Ar* metastables

    NASA Astrophysics Data System (ADS)

    Han, Jiande; Heaven, Michael C.; Emmons, Daniel; Perram, Glen P.; Weeks, David E.; Bailey, William F.

    2016-03-01

    The production of relatively high densities of Ar* metastables (>1012 cm-3) in Ar/He mixtures, at total pressures close to 1 atm, is essential for the efficient operation of an optically pumped Ar* laser. We have used emission spectroscopy and diode laser absorption spectroscopy measurements to observe the production and decay of Ar* in a parallel plate pulsed discharge. With discharge pulses of 1 μs duration we find that metastable production is dominated by processes occurring within the first 100 ns of the gas break-down. Application of multiple, closely spaced discharge pulses yields insights concerning conditions that favor metastable production. This information has been combined with time-resolved measurements of voltage and current. The experimental results and preliminary modeling of the discharge kinetics are presented.

  12. ACL reconstruction - discharge

    MedlinePlus

    Anterior cruciate ligament reconstruction - discharge; ACL reconstruction - discharge ... had surgery to reconstruct your anterior cruciate ligament (ACL). The surgeon drilled holes in the bones of ...

  13. Vacuum ultraviolet emission spectrum measurement of a microwave-discharge hydrogen-flow lamp in several configurations: Application to photodesorption of CO ice

    SciTech Connect

    Chen, Y.-J.; Wu, C.-Y. R.; Chuang, K.-J.; Chu, C.-C.; Yih, T.-S.; Muñoz Caro, G. M.; Nuevo, M.; Ip, W.-H.

    2014-01-20

    We report measurements of the vacuum ultraviolet (VUV) emission spectra of a microwave-discharge hydrogen-flow lamp (MDHL), a common tool in astrochemistry laboratories working on ice VUV photoprocessing. The MDHL provides hydrogen Ly-α (121.6 nm) and H{sub 2} molecular emission in the 110-180 nm range. We show that the spectral characteristics of the VUV light emitted in this range, in particular the relative proportion of Ly-α to molecular emission bands, strongly depend on the pressure of H{sub 2} inside the lamp, the lamp geometry (F type versus T type), the gas used (pure H{sub 2} versus H{sub 2} seeded in He), and the optical properties of the window used (MgF{sub 2} versus CaF{sub 2}). These different configurations are used to study the VUV irradiation of CO ice at 14 K. In contrast to the majority of studies dedicated to the VUV irradiation of astrophysical ice analogs, which have not taken into consideration the emission spectrum of the MDHL, our results show that the processes induced by photons in CO ice from a broad energy range are different and more complex than the sum of individual processes induced by monochromatic sources spanning the same energy range, as a result of the existence of multistate electronic transitions and discrepancy in absorption cross sections between parent molecules and products in the Ly-α and H{sub 2} molecular emission ranges.

  14. Measurement of insulation integrity of IUE camera tube facsimiles by partial discharges method and diffusion of gases through various silicone rubbers

    NASA Technical Reports Server (NTRS)

    Bever, R. S.

    1977-01-01

    Several dummy tubes imitating the IUE Camera System design were encapsulated with Solithane 2, Conathane EN-11, Green and Black Hysols and SMRD 432. Various flaws were purposefully placed in some of these. Partial discharge testing in vacuum under direct voltage conditions was carried once a week for 12 weeks, 15 kv dc being applied during normal working hours for 40 hours duration per week. None of the units showed much damage during this time judging by the P.D. energy histograms. A more complete mathematical presentation is given on diffusion and permeation than previously. Measurements of diffusion constants for various silicone rubbers are carried out by the Time-Lag method and compared to other determinations in the literature. Calculations of the time required for diffusion through a thick wall are demonstrated in the long time approximation and for dimensions pertaining to void and wall sizes of a delamination problem in the LANDSAT-C vidicon tubes. An actual delaminated LANDSAT-C tube and some facsimiles are immersed in vacuum for long periods and tested for catastrophic breakdown due to diffusion of gas, by application of high voltage.

  15. Assessing land-ocean connectivity via Submarine Groundwater Discharge (SGD) in the Ria Formosa Lagoon (Portugal): combining radon measurements and stable isotope hydrology

    NASA Astrophysics Data System (ADS)

    Rocha, C.; Veiga-Pires, C.; Scholten, J.; Knoeller, K.; Gröcke, D. R.; Carvalho, L.; Anibal, J.; Wilson, J.

    2015-11-01

    Natural radioactive tracer-based assessments of basin-scale Submarine Groundwater Discharge (SGD) are well developed, but because of the different modes in which SGD takes place and the wide range of spatial and temporal scales under which the flow and discharge mechanisms involved occur, quantifying SGD while discriminating its source functions remains a major challenge. Yet, correctly identifying both the fluid source and composition is critical: when multiple sources of the tracer of interest are present, failure to adequately discriminate between them will lead to inaccurate attribution and the resulting uncertainties will affect the reliability of SGD solute loading estimates. This lack of reliability then extends to the closure of local biogeochemical budgets, confusing measures aiming to mitigate pollution. Here, we report a multi-tracer study to identify the sources of SGD, distinguish its component parts and elucidate the mechanisms of their dispersion throughout the Ria Formosa - a seasonally hypersaline lagoon in Portugal. We combine radon budgets that determine the total SGD (meteoric + recirculated seawater) in the system with stable isotopes in water (2H, 18O), to specifically identify SGD source functions and characterize active hydrological pathways in the catchment. Using this approach, SGD in the Ria Formosa could be separated into a net water input and another involving no net water transfer, i.e. originating in seawater recirculation through permeable sediments. The former SGD mode is present occasionally on a multiannual timescale, while the latter is a permanent feature of the system. In the absence of meteoric SGD inputs, seawater recirculation through beach sediments occurs at a rate of ~ 1.4 × 106 m3 day-1, implying the entire tidal-averaged volume of the lagoon is filtered through local sandy sediments within 100 days, or about 3.5 times a year, driving an estimated nitrogen (N) load of ~ 350 t N yr-1 into the system as NO3-. Land

  16. Assessing land-ocean connectivity via submarine groundwater discharge (SGD) in the Ria Formosa Lagoon (Portugal): combining radon measurements and stable isotope hydrology

    NASA Astrophysics Data System (ADS)

    Rocha, Carlos; Veiga-Pires, Cristina; Scholten, Jan; Knoeller, Kay; Gröcke, Darren R.; Carvalho, Liliana; Anibal, Jaime; Wilson, Jean

    2016-08-01

    Natural radioactive tracer-based assessments of basin-scale submarine groundwater discharge (SGD) are well developed. However, SGD takes place in different modes and the flow and discharge mechanisms involved occur over a wide range of spatial and temporal scales. Quantifying SGD while discriminating its source functions therefore remains a major challenge. However, correctly identifying both the fluid source and composition is critical. When multiple sources of the tracer of interest are present, failure to adequately discriminate between them leads to inaccurate attribution and the resulting uncertainties will affect the reliability of SGD solute loading estimates. This lack of reliability then extends to the closure of local biogeochemical budgets, confusing measures aiming to mitigate pollution.Here, we report a multi-tracer study to identify the sources of SGD, distinguish its component parts and elucidate the mechanisms of their dispersion throughout the Ria Formosa - a seasonally hypersaline lagoon in Portugal. We combine radon budgets that determine the total SGD (meteoric + recirculated seawater) in the system with stable isotopes in water (δ2H, δ18O), to specifically identify SGD source functions and characterize active hydrological pathways in the catchment. Using this approach, SGD in the Ria Formosa could be separated into two modes, a net meteoric water input and another involving no net water transfer, i.e., originating in lagoon water re-circulated through permeable sediments. The former SGD mode is present occasionally on a multi-annual timescale, while the latter is a dominant feature of the system. In the absence of meteoric SGD inputs, seawater recirculation through beach sediments occurs at a rate of ˜ 1.4 × 106 m3 day-1. This implies that the entire tidal-averaged volume of the lagoon is filtered through local sandy sediments within 100 days ( ˜ 3.5 times a year), driving an estimated nitrogen (N) load of ˜ 350 Ton N yr-1 into the system

  17. A modified beam-to-earth transformation to measure short-wavelength internal waves with an acoustic Doppler current profiler

    USGS Publications Warehouse

    Scotti, A.; Butman, B.; Beardsley, R.C.; Alexander, P.S.; Anderson, S.

    2005-01-01

    The algorithm used to transform velocity signals from beam coordinates to earth coordinates in an acoustic Doppler current profiler (ADCP) relies on the assumption that the currents are uniform over the horizontal distance separating the beams. This condition may be violated by (nonlinear) internal waves, which can have wavelengths as small as 100-200 m. In this case, the standard algorithm combines velocities measured at different phases of a wave and produces horizontal velocities that increasingly differ from true velocities with distance from the ADCP. Observations made in Massachusetts Bay show that currents measured with a bottom-mounted upward-looking ADCP during periods when short-wavelength internal waves are present differ significantly from currents measured by point current meters, except very close to the instrument. These periods are flagged with high error velocities by the standard ADCP algorithm. In this paper measurements from the four spatially diverging beams and the backscatter intensity signal are used to calculate the propagation direction and celerity of the internal waves. Once this information is known, a modified beam-to-earth transformation that combines appropriately lagged beam measurements can be used to obtain current estimates in earth coordinates that compare well with pointwise measurements. ?? 2005 American Meteorological Society.

  18. Preliminary Figures of Merit for Isotope Ratio Measurements: The Liquid Sampling-Atmospheric Pressure Glow Discharge Microplasma Ionization Source Coupled to an Orbitrap Mass Analyzer

    NASA Astrophysics Data System (ADS)

    Hoegg, Edward D.; Barinaga, Charles J.; Hager, George J.; Hart, Garret L.; Koppenaal, David W.; Marcus, R. Kenneth

    2016-08-01

    In order to meet a growing need for fieldable mass spectrometer systems for precise elemental and isotopic analyses, the liquid sampling-atmospheric pressure glow discharge (LS-APGD) has a number of very promising characteristics. One key set of attributes that await validation deals with the performance characteristics relative to isotope ratio precision and accuracy. Owing to its availability and prior experience with this research team, the initial evaluation of isotope ratio (IR) performance was performed on a Thermo Scientific Exactive Orbitrap instrument. While the mass accuracy and resolution performance for Orbitrap analyzers are well-documented, no detailed evaluations of the IR performance have been published. Efforts described here involve two variables: the inherent IR precision and accuracy delivered by the LS-APGD microplasma and the inherent IR measurement qualities of Orbitrap analyzers. Important to the IR performance, the various operating parameters of the Orbitrap sampling interface, high-energy collisional dissociation (HCD) stage, and ion injection/data acquisition have been evaluated. The IR performance for a range of other elements, including natural, depleted, and enriched uranium isotopes was determined. In all cases, the precision and accuracy are degraded when measuring low abundance (<0.1% isotope fractions). In the best case, IR precision on the order of 0.1% RSD can be achieved, with values of 1%-3% RSD observed for low-abundance species. The results suggest that the LS-APGD is a promising candidate for field deployable MS analysis and that the high resolving powers of the Orbitrap may be complemented with a here-to-fore unknown capacity to deliver high-precision IRs.

  19. Preliminary Figures of Merit for Isotope Ratio Measurements: The Liquid Sampling-Atmospheric Pressure Glow Discharge Microplasma Ionization Source Coupled to an Orbitrap Mass Analyzer.

    PubMed

    Hoegg, Edward D; Barinaga, Charles J; Hager, George J; Hart, Garret L; Koppenaal, David W; Marcus, R Kenneth

    2016-08-01

    In order to meet a growing need for fieldable mass spectrometer systems for precise elemental and isotopic analyses, the liquid sampling-atmospheric pressure glow discharge (LS-APGD) has a number of very promising characteristics. One key set of attributes that await validation deals with the performance characteristics relative to isotope ratio precision and accuracy. Owing to its availability and prior experience with this research team, the initial evaluation of isotope ratio (IR) performance was performed on a Thermo Scientific Exactive Orbitrap instrument. While the mass accuracy and resolution performance for Orbitrap analyzers are well-documented, no detailed evaluations of the IR performance have been published. Efforts described here involve two variables: the inherent IR precision and accuracy delivered by the LS-APGD microplasma and the inherent IR measurement qualities of Orbitrap analyzers. Important to the IR performance, the various operating parameters of the Orbitrap sampling interface, high-energy collisional dissociation (HCD) stage, and ion injection/data acquisition have been evaluated. The IR performance for a range of other elements, including natural, depleted, and enriched uranium isotopes was determined. In all cases, the precision and accuracy are degraded when measuring low abundance (<0.1% isotope fractions). In the best case, IR precision on the order of 0.1% RSD can be achieved, with values of 1%-3% RSD observed for low-abundance species. The results suggest that the LS-APGD is a promising candidate for field deployable MS analysis and that the high resolving powers of the Orbitrap may be complemented with a here-to-fore unknown capacity to deliver high-precision IRs. Graphical Abstract ᅟ. PMID:27080006

  20. Preliminary Figures of Merit for Isotope Ratio Measurements: The Liquid Sampling-Atmospheric Pressure Glow Discharge Microplasma Ionization Source Coupled to an Orbitrap Mass Analyzer

    NASA Astrophysics Data System (ADS)

    Hoegg, Edward D.; Barinaga, Charles J.; Hager, George J.; Hart, Garret L.; Koppenaal, David W.; Marcus, R. Kenneth

    2016-04-01

    In order to meet a growing need for fieldable mass spectrometer systems for precise elemental and isotopic analyses, the liquid sampling-atmospheric pressure glow discharge (LS-APGD) has a number of very promising characteristics. One key set of attributes that await validation deals with the performance characteristics relative to isotope ratio precision and accuracy. Owing to its availability and prior experience with this research team, the initial evaluation of isotope ratio (IR) performance was performed on a Thermo Scientific Exactive Orbitrap instrument. While the mass accuracy and resolution performance for Orbitrap analyzers are well-documented, no detailed evaluations of the IR performance have been published. Efforts described here involve two variables: the inherent IR precision and accuracy delivered by the LS-APGD microplasma and the inherent IR measurement qualities of Orbitrap analyzers. Important to the IR performance, the various operating parameters of the Orbitrap sampling interface, high-energy collisional dissociation (HCD) stage, and ion injection/data acquisition have been evaluated. The IR performance for a range of other elements, including natural, depleted, and enriched uranium isotopes was determined. In all cases, the precision and accuracy are degraded when measuring low abundance (<0.1% isotope fractions). In the best case, IR precision on the order of 0.1% RSD can be achieved, with values of 1%-3% RSD observed for low-abundance species. The results suggest that the LS-APGD is a promising candidate for field deployable MS analysis and that the high resolving powers of the Orbitrap may be complemented with a here-to-fore unknown capacity to deliver high-precision IRs.

  1. GAS DISCHARGE DEVICES

    DOEpatents

    Arrol, W.J.; Jefferson, S.

    1957-08-27

    The construction of gas discharge devices where the object is to provide a gas discharge device having a high dark current and stabilized striking voltage is described. The inventors have discovered that the introduction of tritium gas into a discharge device with a subsequent electrical discharge in the device will deposit tritium on the inside of the chamber. The tritium acts to emit beta rays amd is an effective and non-hazardous way of improving the abovementioned discharge tube characteristics

  2. Aortic aneurysm repair - endovascular- discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000236.htm Aortic aneurysm repair - endovascular - discharge To use the sharing features ... enable JavaScript. AAA repair - endovascular - discharge; Repair - aortic aneurysm - endovascular - discharge; EVAR - discharge; Endovascular aneurysm repair - discharge ...

  3. Structure of the upper layer of the Kara Sea influenced by Ob and Yenisei discharge based on continuous thermohaline and optical measurements

    NASA Astrophysics Data System (ADS)

    Osadchiev, Alexander; Zavialov, Peter; Izhitskiy, Alexander; Polukhin, Alexander; Pelevin, Vadim; Makkaveev, Petr; Toktamysova, Zhamal

    2015-04-01

    The Kara Sea is significantly affected by continental runoff annually receiving about 1350 km3 of river waters. More than 70% of this volume is discharged from Ob and Yenisei gulfs in June - September and forms a buoyant plume that occupies up to 40% of the Kara Sea area. This work is focused on the structure of the upper layer of the southern part of the Kara Sea in September, 2011 which was dominated by large freshwater discharge. The research is based on the statistical analysis of in situ data collected during the 59th cruise of the R/V "Academician Mstislav Keldysh" along the ship track using a pump-through system (temperature, salinity, pH) and ultraviolet fluorescent lidar (concentrations of chlorophyll, total suspended matter and colored dissolved organic matter) with high space resolution (about 100 m). We performed principal component analysis of the large dataset to identify the areas where the considered water parameters can regard as passive tracers of river discharge. Proximity of discharge volumes of Ob and Yenisei rivers together with difference in their thermohaline and chemical properties relatively big distance between Ob and Yenisei gulfs (about 200 km) result in strong nonuniformity of the freshened plume. The subsequent cluster analysis identified spatial characteristics of different water masses within the studied river plume formed by two sources of freshwater discharge.

  4. A Three-Year Comparison of Hydrological Measurements in Seven Streams During Breakup in the National Petroleum Reserve - Alaska

    NASA Astrophysics Data System (ADS)

    Vas, D. A.; Toniolo, H. A.; Kemnitz, R.; Lamb, E.

    2012-12-01

    National Petroleum Reserve-Alaska (NPR-A) is an extensive 22.8 million acre oil, gas, and coal rich area that extends from the north foothills of the Brooks range all the way to the Arctic Ocean. Due to increasing demand for oil and natural gas the United States Department of Interior, Bureau of Land Management (BLM) is holding annual oil and gas lease sales in the NPR-A region. BLM is also supporting research to aid responsible oil exploration in the NPR-A region. We conducted a set of hydraulic measurements, which includes discharge measurements using Acoustic Doppler Current Profiler (ADCP), water slope, and suspended sediment sampling during breakup, the most important hydrologic event of the year, from 2010 to 2012 on Otuk Creek, Seabee Creek, Prince Creek, Ikpikpuk River, Judy Creek, Fish Creek, and Ublutuoch River in the NPR - A region. The hydraulic data we collected helped us understand how rivers change yearly which is useful for the development of new infrastructure such as pipe lines, bridges, and roads in the NPR-A region. The goal of this work is to present the results of our 2010 to 2012 spring breakup measurements.

  5. Corona Discharge in Clouds

    NASA Astrophysics Data System (ADS)

    Sin'kevich, A. A.; Dovgalyuk, Yu. A.

    2014-04-01

    We present a review of the results of theoretical studies and laboratory modeling of corona discharge initiation in clouds. The influence of corona discharges on the evolution of the cloud microstructure and electrification is analyzed. It is shown that corona discharges are initiated when large-size hydrometeors approach each other, whereas in some cases, corona discharges from crystals, ice pellets, and hailstones can appear. The corona discharges lead to significant air ionization, charging of cloud particles, and separation of charges in clouds and initiate streamers and lightnings. The influence of corona discharges on changes in the phase composition of clouds is analyzed.

  6. START High Performance Discharges

    NASA Astrophysics Data System (ADS)

    Gates, D. A.

    1997-11-01

    Improvements to START (Small Tight Aspect Ratio Tokamak), the first spherical tokamak in the world to achieve high plasma temperature with both a significant pulse length and confinement time, have been ongoing since 1991. Recent modifications include: expansion of the existing capacitor banks allowing plasma currents as high as 300kA, an increase in the available neutral beam heating power ( ~ 500kW), and improvements to the vacuum system. These improvements have led to the achievement of the world record plasma β (≡ 2μ_0 /B^2) of ~ 30% in a tokamak. The normalised β ( βN ≡ β aB/I_p) reached 4.5 with q_95 = 2.3. Properties of the reconstructed equilibrium will be discussed in detail. The theoretical limit to β is higher in a spherical tokamak than in a conventional machine, due to the higher values of normalised current (IN ≡ I_p/aB) achievable at low aspect ratio. The record β was achieved with IN ~ 8 while conventional tokamaks are limited to IN ~ 3, or less. Calculations of the ideal MHD stability of the record discharge indicate high β low-n kink modes are stable, but that the entire profile is at or near marginal stability for high-n ballooning modes. The phenomenology of the events leading up to the plasma termination is discussed. An important aspect of the START program is to explore the physics of neutral beam absorption at low aspect ratio. A passive neutral particle analyser has been used to study the temporal and spatial dependence of the fast hydrogen beam ions. These measurements have been used in conjunction with a single particle orbit code to estimate the fast ion losses due to collisions with slow neutrals from the plasma edge. Numerical analysis of neutral beam power deposition profiles are compared with the data from an instrumented beam stop. The global energy confinement time τE in beam heated discharges on START is similar to that obtained in Ohmic discharges, even though the input power has roughly doubled over the Ohmic case

  7. Vibrational mode deactivation rates for gaseous discharge-excited nitrogen(2) on selected surfaces measured with coherent anti-Stokes Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Parish, John Walter, Jr.

    2000-09-01

    The disposal rate of nitrogen molecule internal-mode energy, kv , by deactivation in the presence of various surfaces was studied at low pressure and at approximately room temperature using coherent anti-Stokes Raman spectroscopy (CARS). Deactivation is the process whereby vibrational energy is lost one quantum or a few quanta at a time rather than all at once as in quenching. Deactivation coefficients, γv, or loss probabilities, of vibrationally-excited N2(X1Σg +,v) on gold, Pyrex, Teflon and alloys of aluminum, stainless steel and titanium, were calculated from the wall deactivation rate coefficients for the hot band quantum numbers v = 1 to 4 or 5. Vibration states were populated with a 1.5 cm diameter water-cooled-in- glass positive column discharge where the residence time was estimated to be about 60 ms in the tube. The flow rate and pressure were adjusted to optimize the populations and the observed decay. Subsequently, the excited gas was presented via a source tube to a tubular reactor. For precisely controlled residence times, the excited nitrogen would communicate with the reactor interior surface. Only the gas that had been exposed to the surface was measured upon exit from the reactor by a CARS system in the 3-D BOXCARS configuration. Extensive measurements on Pyrex gave γ 1 values between 2.4 × 10-4 and 6.7 × 10-4 depending on the treatment history of the surface. The values for γ4 ranged from 2.9 × 10-4 for the AMS 4943D alloy of titanium to approximately unity for the AMS 312 stainless steel alloy. The low value for titanium can be attributed to the oxide layer. The variation of kv with v was linear or nearly linear in all cases with slopes lower in most cases than the rate of increase of the vibration-translation V-T exchange rate with v. Direct measurement of rates, in this way, detects losses due to homogeneous gas collisions as well as heterogeneous collisions with the surface. An attempt to extract the true value of γv from the data was

  8. Acoustic effects of single electrostatic discharges

    NASA Astrophysics Data System (ADS)

    Orzech, Łukasz

    2015-10-01

    Electric discharges, depending on their character, can emit different types of energy, resulting in different effects. Single electrostatic discharges besides generation of electromagnetic pulses are also the source of N acoustic waves. Their specified parameters depending on amount of discharging charge enable determination of value of released charge in a function of acoustic descriptor (e.g. acoustic pressure). Presented approach is the basics of acoustic method for measurement of single electrostatic discharges, enabling direct and contactless measurement of value of charge released during ESD. Method for measurement of acoustic effect of impact of a single electrostatic discharge on the environment in a form of pressure shock wave and examples of acoustic descriptors in a form of equation Q=f(pa) are described. The properties of measuring system as well as the results of regression static analyses used to determine the described relationships are analysed in details.

  9. Pediatric heart surgery - discharge

    MedlinePlus

    ... reduced appetite Alternate Names Congenital heart surgery - discharge; Patent ductus arteriosus ligation - discharge; Hypoplastic left heart repair - ... of the aorta Congenital heart defect - corrective surgery Patent ductus arteriosus Pediatric heart surgery Tetralogy of Fallot ...

  10. Elbow replacement - discharge

    MedlinePlus

    Total elbow arthroplasty - discharge; Endoprosthetic elbow replacement - discharge ... You had surgery to replace your elbow joint with artificial joint parts (prosthetics). The surgeon made a cut (incision) in the back of your upper or lower arm and ...

  11. Hysterectomy - abdominal - discharge

    MedlinePlus

    ... fibroids Patient Instructions Getting out of bed after surgery Hysterectomy - laparoscopic - discharge Hysterectomy - vaginal - discharge Update Date 1/16/2015 Updated by: Cynthia D. White, MD, Fellow American College of Obstetricians and Gynecologists, Group Health Cooperative, Bellevue, WA. ...

  12. Foot amputation - discharge

    MedlinePlus

    Amputation - foot - discharge; Trans-metatarsal amputation - discharge ... You have had a foot amputation. You may have had an accident, or your foot may have had an infection or disease and doctors could ...

  13. Measurements in N2-CH4(C2H2) discharges of reaction rates and thermochemical constants for Titan atmosphere study.

    PubMed

    Ricard, A; Cernogora, G; Fitaire, M; Hochard, L; Kouassi, N; Speller, C; Vacher, J R

    1995-01-01

    The kinetic reactions in N2-xCH4(C2H2) gas discharges with x less than 1% have been studied by emission spectroscopy in the afterglow of D.C. discharges and by mass spectroscopy from radiolysis ionization using alpha particles. The pressure range is from several Torr to 100 Torr. At the end of N2 D.C. discharges at room temperature, for a residence time of about 10(-2) s, the dominant active species are the N atoms with density of 10(14)-10(15) cm-3 for N2 density of about 10(17) cm-3 (3 Torr), the N2(X,V) vibrational molecules with for example [N2(X,V = 10)] approximately 10(14) cm-3 and the electronic metastable molecules N2(A 3 sigma u +) with a density of 10(12) cm-3. In such conditions, the following kinetic reactions have been studied: N2(A) + N2(A) --> N2(C,B,V') + N2(X), N2(A) + N2(X,V>5) --> N2(X) + N2(B,V') in pure N2 post-discharges and N2(A) + CH4 --> products, C + N + M2 --> CN(B,V') + M2, N2(X,V>4) + CN --> N2(X) + CN(B,A,V'), in N2-1% CH4 post-discharges. The clustering reactions of N2-(1-5%)CH4(C2H2) gas mixtures after radiolysis ionization have been studied for the H2CN+ nN2 ions and the equilibrium constants have been determined in the temperature range T = 140-300 K. PMID:11538437

  14. Nurse-led discharge.

    PubMed

    Page, Carole

    2010-12-01

    Delayed discharges have financial implications for hospital trusts and cause dissatisfaction for patients and their families. This article looks at nurse-led discharge pathways at Milton Keynes Hospital's ambulatory care unit. It explains how giving nurses the responsibility to discharge has improved the patient experience, made nurses more accountable and saved money for the trust. PMID:21229868

  15. Anti-reflux surgery - children - discharge

    MedlinePlus

    Fundoplication - children - discharge; Nissen fundoplication - children - discharge; Belsey (Mark IV) fundoplication - children - discharge; Toupet fundoplication - children - discharge; Thal fundoplication - ...

  16. Statistical summaries of streamflow data for selected gaging stations in Idaho and western Wyoming through September 1990: volume 2: gaging stations with 5 to 9 years of record or that measure discharge from springs

    USGS Publications Warehouse

    Kjelstrom, L.C.; Stone, M.A.J.; Harenberg, W.A.

    1995-01-01

    This volume presents statistical summaries of streamflow data for 76 gaging stations with 5 to 9 years of continuous record, or with records of discharge measurements from springs, through September 1990. The gaging stations are located in Idaho and western Wyoming. Some of the gaging stations at which spring discharge is measured have 10 or more years of record. Volume 1 presents statistical summaries of streamflow data for 257 gaging stations with 10 or more years of continuous record through September 1990. The gaging stations are located in Idaho and adjacent States. Streamflow statistics generated for gaging stations with 5 to 9 years of record or that measure discharge from springs were (1) magnitudes of monthly and annual flows; (2) duration of daily mean flows; and (3) maximum, median, and minimum daily mean flows. Streamflow statistics generated for stations with 10 or more years of record (volume 1) were (1) magnitudes of monthly and annual flows; (2) magnitudes and frequencies of daily low, high, instantaneous peak (flood frequency), and annual mean flows; (3) duration of daily mean flows; and (4) maximum, median, and minimum daily mean flows.

  17. Estimating sediment discharge: Appendix D

    USGS Publications Warehouse

    Gray, John R.; Simões, Francisco J. M.

    2008-01-01

    Sediment-discharge measurements usually are available on a discrete or periodic basis. However, estimates of sediment transport often are needed for unmeasured periods, such as when daily or annual sediment-discharge values are sought, or when estimates of transport rates for unmeasured or hypothetical flows are required. Selected methods for estimating suspended-sediment, bed-load, bed- material-load, and total-load discharges have been presented in some detail elsewhere in this volume. The purposes of this contribution are to present some limitations and potential pitfalls associated with obtaining and using the requisite data and equations to estimate sediment discharges and to provide guidance for selecting appropriate estimating equations. Records of sediment discharge are derived from data collected with sufficient frequency to obtain reliable estimates for the computational interval and period. Most sediment- discharge records are computed at daily or annual intervals based on periodically collected data, although some partial records represent discrete or seasonal intervals such as those for flood periods. The method used to calculate sediment- discharge records is dependent on the types and frequency of available data. Records for suspended-sediment discharge computed by methods described by Porterfield (1972) are most prevalent, in part because measurement protocols and computational techniques are well established and because suspended sediment composes the bulk of sediment dis- charges for many rivers. Discharge records for bed load, total load, or in some cases bed-material load plus wash load are less common. Reliable estimation of sediment discharges presupposes that the data on which the estimates are based are comparable and reliable. Unfortunately, data describing a selected characteristic of sediment were not necessarily derived—collected, processed, analyzed, or interpreted—in a consistent manner. For example, bed-load data collected with

  18. Increasing river discharge to the Arctic Ocean.

    PubMed

    Peterson, Bruce J; Holmes, Robert M; McClelland, James W; Vörösmarty, Charles J; Lammers, Richard B; Shiklomanov, Alexander I; Shiklomanov, Igor A; Rahmstorf, Stefan

    2002-12-13

    Synthesis of river-monitoring data reveals that the average annual discharge of fresh water from the six largest Eurasian rivers to the Arctic Ocean increased by 7% from 1936 to 1999. The average annual rate of increase was 2.0 +/- 0.7 cubic kilometers per year. Consequently, average annual discharge from the six rivers is now about 128 cubic kilometers per year greater than it was when routine measurements of discharge began. Discharge was correlated with changes in both the North Atlantic Oscillation and global mean surface air temperature. The observed large-scale change in freshwater flux has potentially important implications for ocean circulation and climate. PMID:12481132

  19. Numerical Simulation on Measurement of Optical and Thermal Properties for Warm Dense Matter Generated by Isochoric Heating with Pulsed Power Discharge Device

    NASA Astrophysics Data System (ADS)

    KIKUCHI, Takashi; HAYASHI, Ryota; TAKAHASHI, Takuya; TAMURA, Fumihiro; TAKAHASHI, Kazumasa; SASAKI, Toru; ASO, Tsukasa; HARADA, Nob.

    2016-03-01

    Property data in warm dense matter (WDM) are important to optimize implosion dynamics in a fuel pellet of inertial confinement fusion (ICF). A table-top pulsed power discharge device with isochoric heating using a sapphire hollow capillary was proposed, and was used to generate the extreme state of matter with a well-defined condition. We investigated numerically to generate the WDM by using the pulsed power discharge device. The numerical model was developed by time-dependent one-dimensional thermal diffusion with radiative transfer of multi-group approximation, and the numerical simulation was carried out according with the experimental condition. The achieved temperature of the numerical simulation result was confirmed by the previous experimental result. Also, the radiation energy density was shown at each group of the wavelength of emission.

  20. Kinetic model and spectroscopic measurement of NO (A, B, C) states in low-pressure N2-O2 microwave discharge

    NASA Astrophysics Data System (ADS)

    Tan, Hao; Nezu, Atsushi; Akatsuka, Hiroshi

    2015-09-01

    A self-consistent kinetic model is developed to study the atomic and molecular processes in the microwave discharge plasma of N2-O2 mixtures. We focus on the NO A 2Σ+, B 2Π, and C 2Π states in the mixture discharge. We find good agreement between the calculated and experimental NO A 2Σ+ densities. On the other hand, the radiation bands from the NO B 2Π and C 2Π states are observed only when the oxygen partial pressure is less than 3%. We discuss the de-excitation processes for the NO B 2Π and C 2Π states in this low-pressure plasma. We also propose that the de-excitation processes involve collision with O2 X 3Σ \\text{g} - for these levels, which can explain the observed spectral disappearance.

  1. Carburetor fuel discharge assembly

    SciTech Connect

    Yost, R.M.

    1993-06-29

    An improved carburetor for use on an internal combustion engine is described, the carburetor having an airflow passage and fuel discharge means for admitting fuel into the airflow passage for mixing the fuel with air flowing in the airflow passage to form a fuel/air mixture to be supplied to the combustion chamber(s) of the engine, the fuel discharge means including a fuel discharge assembly which comprises a hollow discharge tube and fuel supplying means connected to the discharge tube for admitting fuel into the interior of the discharge tube, wherein the discharge tube has a longitudinal internal bore in fluid communication with the fuel supplying means, wherein the internal bore extends between an inlet that is closest to the fuel supplying means and an outlet that is furthest from the fuel supplying means with the outlet of the bore being located within the airflow passage of the carburetor to supply fuel into this passage after the fuel passes from the fuel supplying means through the internal bore of the discharge tube, wherein the improvement relates to the fuel discharge assembly and comprises: a hollow fuel flow guide tube telescopically received inside the internal bore of the discharge tube, wherein the fuel flow guide tube extends from approximately the location of the inlet of the bore up at least a portion of the length of the bore towards the outlet of the bore to conduct fuel from the fuel supplying means into the bore of the discharge tube.

  2. Computation of fluvial-sediment discharge

    USGS Publications Warehouse

    Porterfield, George

    1972-01-01

    This report is one of a series concerning the concepts, measurement, laboratory procedures, and computation of fluvial-sediment discharge. Material in this report includes procedures and forms used to compile and evaluate particle-size and concentration data, to compute fluvial-sediment discharge, and to prepare sediment records for publication.

  3. Helicon plasma thruster discharge model

    SciTech Connect

    Lafleur, T.

    2014-04-15

    By considering particle, momentum, and energy balance equations, we develop a semi-empirical quasi one-dimensional analytical discharge model of radio-frequency and helicon plasma thrusters. The model, which includes both the upstream plasma source region as well as the downstream diverging magnetic nozzle region, is compared with experimental measurements and confirms current performance levels. Analysis of the discharge model identifies plasma power losses on the radial and back wall of the thruster as the major performance reduction factors. These losses serve as sinks for the input power which do not contribute to the thrust, and which reduce the maximum plasma density and hence propellant utilization. With significant radial plasma losses eliminated, the discharge model (with argon) predicts specific impulses in excess of 3000 s, propellant utilizations above 90%, and thruster efficiencies of about 30%.

  4. Helicon plasma thruster discharge model

    NASA Astrophysics Data System (ADS)

    Lafleur, T.

    2014-04-01

    By considering particle, momentum, and energy balance equations, we develop a semi-empirical quasi one-dimensional analytical discharge model of radio-frequency and helicon plasma thrusters. The model, which includes both the upstream plasma source region as well as the downstream diverging magnetic nozzle region, is compared with experimental measurements and confirms current performance levels. Analysis of the discharge model identifies plasma power losses on the radial and back wall of the thruster as the major performance reduction factors. These losses serve as sinks for the input power which do not contribute to the thrust, and which reduce the maximum plasma density and hence propellant utilization. With significant radial plasma losses eliminated, the discharge model (with argon) predicts specific impulses in excess of 3000 s, propellant utilizations above 90%, and thruster efficiencies of about 30%.

  5. Nonsputtering impulse magnetron discharge

    SciTech Connect

    Khodachenko, G. V.; Mozgrin, D. V.; Fetisov, I. K.; Stepanova, T. V.

    2012-01-15

    Experiments with quasi-steady high-current discharges in crossed E Multiplication-Sign B fields in various gases (Ar, N{sub 2}, H{sub 2}, and SF{sub 6}) and gas mixtures (Ar/SF{sub 6} and Ar/O{sub 2}) at pressures from 10{sup -3} to 5 Torr in discharge systems with different configurations of electric and magnetic fields revealed a specific type of stable low-voltage discharge that does not transform into an arc. This type of discharge came to be known as a high-current diffuse discharge and, later, a nonsputtering impulse magnetron discharge. This paper presents results from experimental studies of the plasma parameters (the electron temperature, the plasma density, and the temperature of ions and atoms of the plasma-forming gas) of a high-current low-pressure diffuse discharge in crossed E Multiplication-Sign B fields.

  6. Spatial and temporal variability of zooplankton off New Caledonia (Southwestern Pacific) from acoustics and net measurements

    NASA Astrophysics Data System (ADS)

    Smeti, Houssem; Pagano, Marc; Menkes, Christophe; Lebourges-Dhaussy, Anne; Hunt, Brian P. V.; Allain, Valerie; Rodier, Martine; de Boissieu, Florian; Kestenare, Elodie; Sammari, Cherif

    2015-04-01

    Spatial and temporal distribution of zooplankton off New Caledonia in the eastern Coral Sea was studied during two multidisciplinary cruises in 2011, during the cool and the hot seasons. Acoustic measurements of zooplankton were made using a shipborne acoustic Doppler current profiler (S-ADCP), a scientific echosounder and a Tracor acoustic profiling system (TAPS). Relative backscatter from ADCP was converted to biomass estimates using zooplankton weights from net-samples collected during the cruises. Zooplankton biomass was estimated using four methods: weighing, digital imaging (ZooScan), ADCP and TAPS. Significant correlations were found between the different biomass estimators and between the backscatters of the ADCP and the echosounder. There was a consistent diel pattern in ADCP derived biomass and echosounder backscatter resulting from the diel vertical migration (DVM) of zooplankton. Higher DVM amplitudes were associated with higher abundance of small zooplankton and cold waters to the south of the study area, while lower DVM amplitudes in the north were associated with warmer waters and higher abundance of large organisms. Zooplankton was largely dominated by copepods (71-73%) among which calanoids prevailed (40-42%), with Paracalanus spp. as the dominant species (16-17%). Overall, zooplankton exhibited low abundance and biomass (mean night dry biomass of 4.7 ± 2.2 mg m3 during the cool season and 2.4 ± 0.4 mg m3 during the hot season) but high richness and diversity (Shannon index ˜4). Substantially enhanced biomass and abundance appeared to be episodically associated with mesoscale features contributing to shape a rather patchy zooplankton distribution.

  7. Angioplasty and stent - heart - discharge

    MedlinePlus

    ... discharge; PTCA - discharge; Percutaneous transluminal coronary angioplasty - discharge; Heart artery dilatation - discharge ... the blood vessels that supply blood to your heart. You may have had a heart attack or ...

  8. Multi-Instrumental Measurement of Bedload Transport and Turbulent Resuspension over Lateral Sand Bars in the Lower Mississippi River

    NASA Astrophysics Data System (ADS)

    Ramirez, M. T.; Allison, M. A.; Meselhe, E. A.; Duncan, D. D.

    2010-12-01

    Two reaches of the lower Mississippi River at Myrtle Grove, LA (river kilometer 95-100 above Head of Passes) and Magnolia, LA (river kilometer 72-76) were examined during rising river discharge in April (23,800 cms) and May (19,300 cms) 2010 using a multi-instrumental approach to observe the dynamics of bedload transport and turbulent resuspension over lateral river sand bars. The key concept is to quantify and model to what extent (vertically and spatially) sediments sourced from the bar contribute to the suspended sand flux sourced from upriver: this issue is critical to determine sediment loads available for capture by planned river diversion structures. Following basemapping of bar morphology with multibeam bathymetry, longitudinal and cross-sectional surveys with ADCP and ABS were used to define the bottom stress field and suspended sediment load from backscatter. Suspended sediment concentrations and particle sizes (disaggregated and aggregate) were measured using isokinetic samplers, and wire-deployed (stationary and towed) LISST and optical sensors (transmissometer, OBS): bottom sands were also sampled by grab. Bedload sediment transport was quantified from repeated multibeam surveys of migrating sand dunes. Preliminary results suggest a depth-related bar effect: the shallower bar at Magnolia shows evidence of larger dunes than Myrtle Grove at a given flow. Discharge is also critical in setting dune size, which has a feedback (form-drag) on the magnitude and height above the bottom of resuspension. Daily surveys during the five-day rising discharge May study captured the threshold for bed sand becoming a significant contributor to the suspended sand flux, particularly at Magnolia.

  9. Computing discharge using the index velocity method

    USGS Publications Warehouse

    Levesque, Victor A.; Oberg, Kevin A.

    2012-01-01

    Application of the index velocity method for computing continuous records of discharge has become increasingly common, especially since the introduction of low-cost acoustic Doppler velocity meters (ADVMs) in 1997. Presently (2011), the index velocity method is being used to compute discharge records for approximately 470 gaging stations operated and maintained by the U.S. Geological Survey. The purpose of this report is to document and describe techniques for computing discharge records using the index velocity method. Computing discharge using the index velocity method differs from the traditional stage-discharge method by separating velocity and area into two ratings—the index velocity rating and the stage-area rating. The outputs from each of these ratings, mean channel velocity (V) and cross-sectional area (A), are then multiplied together to compute a discharge. For the index velocity method, V is a function of such parameters as streamwise velocity, stage, cross-stream velocity, and velocity head, and A is a function of stage and cross-section shape. The index velocity method can be used at locations where stage-discharge methods are used, but it is especially appropriate when more than one specific discharge can be measured for a specific stage. After the ADVM is selected, installed, and configured, the stage-area rating and the index velocity rating must be developed. A standard cross section is identified and surveyed in order to develop the stage-area rating. The standard cross section should be surveyed every year for the first 3 years of operation and thereafter at a lesser frequency, depending on the susceptibility of the cross section to change. Periodic measurements of discharge are used to calibrate and validate the index rating for the range of conditions experienced at the gaging station. Data from discharge measurements, ADVMs, and stage sensors are compiled for index-rating analysis. Index ratings are developed by means of regression

  10. Experimental study of micro electrical discharge machining discharges

    SciTech Connect

    Braganca, I. M. F.; Rosa, P. A. R.; Martins, P. A. F.; Dias, F. M.; Alves, L. L.

    2013-06-21

    Micro electrical discharge machining ({mu}EDM) is an atmospheric-pressure plasma-assisted technology that uses point-to-plane discharges in liquid dielectrics to remove microscopic quantities of electrically conductive materials. In this work, an innovative {mu}EDM prototype machine was specifically designed and fabricated to produce and control single spark discharges, thus, resolving the typical limitations of (multi-discharge) commercial machines. The work analyses the type of discharge and the micro-plasma electron-density values obtained for 0.5-38 {mu}m gap sizes, 3-10 000 {mu}s pulse durations, 75-250 V low breakdown voltages, and 1-20 A discharge currents, using different combinations of metallic electrodes in oil and in water. Results allow fitting, for micro-scale and low voltages, an empirical law between the maximum gap-size for breakdown, the breakdown voltage, and the effective stress-time. The electron density n{sub e} is obtained by optical emission spectroscopy diagnostics of the H{sub {alpha}}-line Stark broadening (yielding n{sub e}{approx}10{sup 16}-10{sup 17} cm{sup -3}, i.e., ionization degrees of {approx}2 Multiplication-Sign 10{sup -5}-10{sup -4}) and by a semi-empirical resistive plasma model. The model uses the experimental values of several electrical and geometrical quantities, and of the gas pressure estimated as {approx}60 bar-2 kbar from measurements of the plasma mechanical action, obtained using a force sensor. The quantitative information of this phenomenological study can assist the optimization of this micro-fabrication technique.

  11. Experimental study of micro electrical discharge machining discharges

    NASA Astrophysics Data System (ADS)

    Bragança, I. M. F.; Rosa, P. A. R.; Dias, F. M.; Martins, P. A. F.; Alves, L. L.

    2013-06-01

    Micro electrical discharge machining (μEDM) is an atmospheric-pressure plasma-assisted technology that uses point-to-plane discharges in liquid dielectrics to remove microscopic quantities of electrically conductive materials. In this work, an innovative μEDM prototype machine was specifically designed and fabricated to produce and control single spark discharges, thus, resolving the typical limitations of (multi-discharge) commercial machines. The work analyses the type of discharge and the micro-plasma electron-density values obtained for 0.5-38 μm gap sizes, 3-10 000 μs pulse durations, 75-250 V low breakdown voltages, and 1-20 A discharge currents, using different combinations of metallic electrodes in oil and in water. Results allow fitting, for micro-scale and low voltages, an empirical law between the maximum gap-size for breakdown, the breakdown voltage, and the effective stress-time. The electron density ne is obtained by optical emission spectroscopy diagnostics of the Hα-line Stark broadening (yielding ne˜1016-1017 cm-3, i.e., ionization degrees of ˜2×10-5-10-4) and by a semi-empirical resistive plasma model. The model uses the experimental values of several electrical and geometrical quantities, and of the gas pressure estimated as ˜60 bar-2 kbar from measurements of the plasma mechanical action, obtained using a force sensor. The quantitative information of this phenomenological study can assist the optimization of this micro-fabrication technique.

  12. Self synchronization of surface discharges

    NASA Astrophysics Data System (ADS)

    Allegraud, Katia; Rousseau, Antoine

    2008-10-01

    Surface dielectric barrier discharges (SDBD) are mainly investigated for airflow control. In this paper, they are used to study surface processes in dielectric barrier discharges. A previous study has shown the self triggered behavior of a SDBD: the plasma initiates through several simultaneous and adjacent filaments around the electrode [1]. This phenomenon has been investigated under the name of collective effects, where the light of a first filament can trigger the ignitions its neighbors [1, 2]. It allows initiating several tens of streamers during a current peak of ˜50 ns. In the present study, we propose to investigate the self synchronization of the discharge in a two electrodes system: the setup consists of two high voltage electrodes on the same glass plate. A third electrode, under the plate, is grounded. ICCD measurements show that the discharge appears simultaneously on both electrodes on a 50 ns time scale. Nanosecond resolved measurements of the streamers propagation reveal that the ignitions on one electrode can be delayed by few nanoseconds in respect to the other one. This means that the discharge from a first electrode can trigger the second one. Finally, iCCD measurements allow calculating the streamers propagation velocity, varying from 3.4x10^7 cm/s at the beginning of the propagation to 0.7x10^7cm/s at the end of the propagation [3]. [1] K. Allegraud, O. Guaitella, A. Rousseau, J. Phys. D. : Appl. Phys. 40 7698--7706 (2007) [2] O. Guaitella, F. Thevenet, C. Guillard, A. Rousseau, J. Phys. D.: Appl. Phys. 39 2964--72 (2006) [3] K. Allegraud, A. Rousseau, submitted to IEEE Transactions on Dielectrics and Electrical Insulation

  13. Internal Electrostatic Discharge Monitor - IESDM

    NASA Technical Reports Server (NTRS)

    Kim, Wousik; Goebel, Dan M.; Jun, Insoo; Garrett, Henry B.

    2011-01-01

    A document discusses an innovation designed to effectively monitor dielectric charging in spacecraft components to measure the potential for discharge in order to prevent damage from internal electrostatic discharge (IESD). High-energy electrons penetrate the structural materials and shielding of a spacecraft and then stop inside dielectrics and keep accumulating. Those deposited charges generate an electric field. If the electric field becomes higher than the breakdown threshold (approx. =2 x 10(exp 5) V/cm), discharge occurs. This monitor measures potentials as a function of dielectric depth. Differentiation of potential with respect to the depth yields electric field. Direct measurement of the depth profile of the potential in a dielectric makes real-time electronic field evaluation possible without simulations. The IESDM has been designed to emulate a multi-layer circuit board, to insert very thin metallic layers between the dielectric layers. The conductors serve as diagnostic monitoring locations to measure the deposited electron-charge and the charge dynamics. Measurement of the time-dependent potential of the metal layers provides information on the amount of charge deposited in the dielectrics and the movement of that charge with time (dynamics).

  14. Discharges Against Medical Advice

    PubMed Central

    Franks, Peter; Meldrum, Sean; Fiscella, Kevin

    2006-01-01

    BACKGROUND Prior literature suggests that blacks are more likely to be discharged against medical advice (DAMA). OBJECTIVE We examined whether DAMA from general hospitals varies by race/ethnicity and whether this variation is explained by individual and hospital factors. DESIGN, SUBJECTS, AND MEASUREMENTS We conducted cross-sectional analyses of 1998 to 2000 hospital discharge data, linked to the American Hospital Association data, on adults admitted for acute general hospital care in California, Florida, and New York. A series of hierarchical logistic regression analyses explored factors associated with DAMA, initially adjusting for age and gender, then sequentially adding adjustment for comorbidities, individual socio-economic factors, and finally hospital characteristics. RESULTS Compared with whites, blacks had a 2-fold higher age-gender adjusted odds of DAMA, a risk that progressively diminished with increasing adjustment (final adjusted odds ratio [OR]=0.95, 95% confidence interval [CI]=0.91, 1.00). While Hispanics had an increased risk of DAMA in age-gender-adjusted analyses, the final model revealed a protective effect (adjusted OR=0.66, 95% CI=0.62, 0.70), similar to that observed for Asians. CONCLUSIONS Disparities in DAMA affecting minority patients in general hospitals are largely accounted for by individual and hospital socio-economic factors. The absence of any adjusted disparity affecting blacks, and the protective effect observed for Hispanics and other minorities suggest that individual discrimination and poor communication are not primary determinants of DAMA, but where patients are admitted does contribute to disparities in DAMA. PMID:16918741

  15. Pelvic radiation - discharge

    MedlinePlus

    Radiation of the pelvis - discharge; Cancer treatment - pelvic radiation; Prostate cancer - pelvic radiation; Ovarian cancer - pelvic radiation; Cervical cancer - pelvic radiation; Uterine cancer - pelvic radiation; Rectal cancer - ...

  16. Diagnostics of High-Intensity-Discharges

    NASA Astrophysics Data System (ADS)

    Adler, Helmar G.

    1996-05-01

    High intensity light sources have come a long way since the introduction of high pressure discharges in mercury and later in sodium. The introduction of other species (e.g. metal halides) into the discharge chemistry led to marked improvements in light intensity (lumens per watt or LPW) and the appearance of the light output (color rendering index or CRI). Many of these improvements have been achieved through qualitative understanding of the discharge and good engineering. The accurate predictions of discharge behavior and spectral power distribution through HID-models remains a difficult and challenging goal for lighting scientists. Modelling of a real lamp is complicated due to the high pressures in the discharge, the geometric influences of the discharge vessel, and the interactions between fills, wall materials and electrodes. The simultaneous use of solid-, liquid-, gaseous- and plasma-state descriptions, including for example effects of radiation transport, becomes necessary. Spectroscopic measurements have been and are still of highest value, not only to determine practical parameters like LPW and CRI, but also to determine species distributions and temperatures, eventually as a function of location in the discharge and time. These measurements are necessary not only for the quantitative understanding of the discharge mechanisms, but also to serve as a testbed for all simulation efforts. This paper will focus on diagnostic possibilities and opportunities using imaging data acquisition systems.

  17. Electrostatic discharge control for STDN stations

    NASA Technical Reports Server (NTRS)

    Mckiernan, J.

    1983-01-01

    This manual defines the requirements and control methods necessary to control the effect of electrostatic discharges that damage or destroy electronic equipment components. Test procedures for measuring the effectiveness of the control are included.

  18. Measurement of vibrational, gas, and rotational temperatures of H2 (X1 Σg+) in radio frequency inductive discharge plasma by multiplex coherent anti-Stokes Raman scattering spectroscopy technique

    NASA Astrophysics Data System (ADS)

    Shakhatov, V. A.; De Pascale, O.; Capitelli, M.; Hassouni, K.; Lombardi, G.; Gicquel, A.

    2005-02-01

    Translational, rotational, and vibrational temperatures of H2 in radio frequency inductive discharge plasmas at pressures and power release ranges, respectively, of 0.5-8 torr and 0.5-2W/cm3 have been measured by using multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopy. Computational codes have been developed to determine the rotational and vibrational temperatures and to analyze H2 CARS spectrum for nonequilibrium conditions. The results show a decrease of the vibrational temperature from 4250 to 2800 K by increasing the pressure from 0.5 to 8 torr and a corresponding increase of the rotational temperature from 525 to 750 K.

  19. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, B.E.; Miller, J.L.; Ault, E.R.

    1994-08-23

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window. 2 figs.

  20. Longitudinal discharge laser electrodes

    DOEpatents

    Warner, Bruce E.; Miller, John L.; Ault, Earl R.

    1994-01-01

    The improved longitudinal discharge laser electrode with IR baffle includes an electrode made up of washers spaced along the laser axis in order to form inter-washer spaces for hollow cathode discharge to take place and for IR radiation to be trapped. Additional IR baffles can be placed between the electrode ann the window.

  1. Lithium battery discharge tests

    NASA Technical Reports Server (NTRS)

    Johnson, C. J.

    1980-01-01

    The long term discharge of a variety of lithium cells was characterized and the susceptibility of the cells to chemical variation during the slow discharge was tested. A shunt resistor was set across the terminals to monitor the voltage as a function of time. Failures were identified by premature voltage drops.

  2. ESTIMATION OF NAVIGATION - DAM DISCHARGE IN ILLINOIS.

    USGS Publications Warehouse

    Weiss, Linda S.

    1987-01-01

    Techniques were used to estimate discharge for the Brandon Road Dam on the Des Plaines River and the Dresden Island, Marseilles, and Starved Rock Dams on the Illinois River in northern Illinois. Tainter gates are operated to regulate streamflow at all dams. Additionally, headgates are used for regulation of the Brandon Road Dam. Stage-discharge, gate-opening relations were developed from a total of 91 discharge measurements that range from 198 to 86,400 cubic feet per second (5. 6 to 2,450 cubic meters per second). Values for discharge coefficients, in equations that express discharge as a function of tailwater depth, headwater depth, and vertical height of gate opening, were determined for conditions of free-orifice, submerged-orifice, free-weir, and submerged-weir flow past a tainter gate.

  3. GAS DISCHARGE DEVICES

    DOEpatents

    Jefferson, S.

    1958-11-11

    An apparatus utilized in introducing tritium gas into envelope of a gas discharge device for the purpose f maintaining the discharge path in ionized condition is described. ln addition to the cathode and anode, the ischarge device contains a zirconium or tantalum ilament arranged for external excitation and a metallic seed containing tritium, and also arranged to have a current passed through it. Initially, the zirconium or tantalum filament is vaporized to deposit its material adjacent the main discharge region. Then the tritium gas is released and, due to its affinity for the first released material, it deposits in the region of the main discharge where it is most effective in maintaining the discharge path in an ionized condition.

  4. CO-AXIAL DISCHARGES

    DOEpatents

    Luce, J.S.; Smith, L.P.

    1960-11-22

    A method and apparatus are given for producing coaxial arc discharges in an evacuated enclosure and within a strong, confining magnetic field. The arcs are maintained at a high potential difference. Electrons will diffuse to the more positive arc from the negative arc, and positive ions will diffuse from the more positive arc to the negative arc. Coaxial arc discharges have the advantage that ions which return to strike the positive arc discharge will lose no energy since they do not strike a solid wall or electrode. Those discharges are useful in confining an ionized plasma between the discharges, and have the advantage of preventing impurities from the walls of the enclosure from entering ihe plasma area because of the arc barrier set up bv the cylindrical outer arc.

  5. Co-axial discharges

    DOEpatents

    Luce, J. S.; Smith, L. P.

    1960-11-22

    An apparatus is described for producing coaxial arc discharges in an evacuated enclosure and within a strong, confining magnetic field. The arcs are maintained at a high potential difference. Electrons diffuse to the more positive arc from the negative arc, and positive ions diffuse from the more positive arc to the negative arc. Coaxial arc discharges have the advantuge that ions that return to strike the positive arc discharge will lose no energy since they do not strike a solid wall or electrode. These discharges are useful in confining an ionized plasma between the discharges and have the advantage of preventing impurities from the walls of the enclosure from entering the plasma area because of the arc barrier set up by the cylindrical outer arc. (auth)

  6. HOLLOW CARBON ARC DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-10-11

    A device is described for producing an energetic, direct current, hollow, carbon-arc discharge in an evacuated container and within a strong magnetic field. Such discharges are particularly useful not only in dissociation and ionization of high energy molecular ion beams, but also in acting as a shield or barrier against the instreaming of lowenergy neutral particles into a plasma formed within the hollow discharge when it is used as a dissociating mechanism for forming the plasma. There is maintained a predetermined ratio of gas particles to carbon particles released from the arc electrodes during operation of the discharge. The carbon particles absorb some of the gas particles and are pumped along and by the discharge out of the device, with the result that smaller diffusion pumps are required than would otherwise be necessary to dispose of the excess gas.

  7. Shock wave propagation in glow discharges

    NASA Astrophysics Data System (ADS)

    Ganguly, B. N.

    1998-10-01

    The modification of acoustic shock wave propagation characteristics in a 25 cm long positive column low pressure (10 to 50 Torr), low current density (2 to 10 mA/cm^2) argon and N2 dc discharges have been measured by laser beam deflection technique. The simultaneous multi point shock velocity, dispersion and damping have been measured both inside and outside the glow discharge region. The local shock velocity is found to increase with the increased propagation path length through the discharge; for Mach number greater than 1.7 the upstream velocity exceeded the downstream velocity in contrast to the opposite behavior in neutral gas. The damping and dispersion are also dependent on the propagation distance. The recovery of the shock dispersion and damping in the post discharge region, for a given discharge condition, are functions of the initial Mach number. The optical measurement of the wall and the gas (rotational) temperatures suggest the observed shock features can not be solely explained by the gas heating in a self sustained discharge. The results are similar for both Ar and N2 discharges showing that vibrational excitation and relaxation are not essential^1. The explanation of the observed weak shock propagation properties in a glow discharge appears to require long range cooperative interactions that enhance heavy particle collisional energy transfer rates for the measured discharge conditions. Unlike collisional shock wave propagation in highly ionized plasmas^2,3, the exact energy coupling mechanism between the nonequilibrium weakly ionized plasma and shock is not understood. 1. A.I. Osipov and A.V. Uvarov, Sov. Phys. Usp. 35, 903 (1992) and other references there in. 2. M. Casanova, O. Larroche and J-P Matte, Phys. Rev. Lett. 67, 2143 (1991). 3. M.C.M. van de Sanden, R. van den Bercken and D.C. Schram, Plasma Sources Sci.Technol. 3, 511 (1994).

  8. Computations of total sediment discharge, Niobrara River near Cody, Nebraska

    USGS Publications Warehouse

    Colby, Bruce R.; Hembree, C.H.

    1955-01-01

    A natural chute in the Niobrara River near Cody, Nebr., constricts the flow of the river except at high stages to a narrow channel in which the turbulence is sufficient to suspend nearly the total sediment discharge. Because much of the flow originates in the sandhills area of Nebraska, the water discharge and sediment discharge are relatively uniform. Sediment discharges based on depth-integrated samples at a contracted section in the chute and on streamflow records at a recording gage about 1,900 feet upstream are available for the period from April 1948 to September 1953 but are not given directly as continuous records in this report. Sediment measurements have been made periodically near the gage and at other nearby relatively unconfined sections of the stream for comparison with measurements at the contracted section. Sediment discharge at these relatively unconfined sections was computed from formulas for comparison with measured sediment discharges at the contracted section. A form of the Du Boys formula gave computed tonnages of sediment that were unsatisfactory. Sediment discharges as computed from the Schoklitsch formula agreed well with measured sediment discharges that were low, but they were much too low at measured sediment discharges that were higher. The Straub formula gave computed discharges, presumably of bed material, that were several times larger than measured discharges of sediment coarser than 0.125 millimeter. All three of these formulas gave computed sediment discharges that increased with water discharges much less rapidly than the measured discharges of sediment coarser than 0.125 millimeter. The Einstein procedure when applied to a reach that included 10 defined cross sections gave much better agreement between computed sediment discharge and measured sediment discharge than did anyone of the three other formulas that were used. This procedure does not compute the discharge of sediment that is too small to be found in the stream bed in

  9. Measurement of bedload transport in sand-bed rivers: a look at two indirect sampling methods

    USGS Publications Warehouse

    Holmes, Robert R., Jr.

    2010-01-01

    Sand-bed rivers present unique challenges to accurate measurement of the bedload transport rate using the traditional direct sampling methods of direct traps (for example the Helley-Smith bedload sampler). The two major issues are: 1) over sampling of sand transport caused by “mining” of sand due to the flow disturbance induced by the presence of the sampler and 2) clogging of the mesh bag with sand particles reducing the hydraulic efficiency of the sampler. Indirect measurement methods hold promise in that unlike direct methods, no transport-altering flow disturbance near the bed occurs. The bedform velocimetry method utilizes a measure of the bedform geometry and the speed of bedform translation to estimate the bedload transport through mass balance. The bedform velocimetry method is readily applied for the estimation of bedload transport in large sand-bed rivers so long as prominent bedforms are present and the streamflow discharge is steady for long enough to provide sufficient bedform translation between the successive bathymetric data sets. Bedform velocimetry in small sandbed rivers is often problematic due to rapid variation within the hydrograph. The bottom-track bias feature of the acoustic Doppler current profiler (ADCP) has been utilized to accurately estimate the virtual velocities of sand-bed rivers. Coupling measurement of the virtual velocity with an accurate determination of the active depth of the streambed sediment movement is another method to measure bedload transport, which will be termed the “virtual velocity” method. Much research remains to develop methods and determine accuracy of the virtual velocity method in small sand-bed rivers.

  10. [Temporal behavior of light emission of dielectric barrier discharges in air at atmospheric pressure].

    PubMed

    Yin, Zeng-qian; Dong, Li-fang; Han, Li; Li, Xue-chen; Chai, Zhi-fang

    2002-12-01

    The experimental setup of dielectric barrier discharge was designed which is propitious to optical measurement. Temporal behavior of light emission of dielectric barrier discharges (filamentary model) in air at atmospheric pressure was measured by using optical method. Temporal behavior of dielectric barrier discharges was obtained. The experimental results show that the discharge burst in each half cycle of applied voltage consists of a series of discharge pulses, the duration of each discharge pulse is about 30-50 ns, and the interval of the neighboring discharge pulses is about a few hundred ns. The result is of great importance to the application of dielectric barrier discharges. PMID:12914154

  11. Electric field in an AC dielectric barrier discharge overlapped with a nanosecond pulse discharge

    NASA Astrophysics Data System (ADS)

    Goldberg, Benjamin M.; Shkurenkov, Ivan; Adamovich, Igor V.; Lempert, Walter R.

    2016-08-01

    The effect of ns discharge pulses on the AC barrier discharge in hydrogen in plane-to-plane geometry is studied using time-resolved measurements of the electric field in the plasma. The AC discharge was operated at a pressure of 300 Torr at frequencies of 500 and 1750 Hz, with ns pulses generated when the AC voltage was near zero. The electric field vector is measured by ps four-wave mixing technique, which generates coherent IR signal proportional to the square of electric field. Absolute calibration was done using an electrostatic (sub-breakdown) field applied to the discharge electrodes, when no plasma was generated. The results are compared with one-dimensional kinetic modeling of the AC discharge and the nanosecond pulse discharge, predicting behavior of both individual micro-discharges and their cumulative effect on the electric field distribution in the electrode gap, using stochastic averaging based on the experimental micro-discharge temporal probability distribution during the AC period. Time evolution of the electric field in the AC discharge without ns pulses, controlled by a superposition of random micro-discharges, exhibits a nearly ‘flat top’ distribution with the maximum near breakdown threshold, reproduced quite well by kinetic modeling. Adding ns pulse discharges on top of the AC voltage waveform changes the AC discharge behavior in a dramatic way, inducing transition from random micro-discharges to a more regular, near-1D discharge. In this case, reproducible volumetric AC breakdown is produced at a well-defined moment after each ns pulse discharge. During the reproducible AC breakdown, the electric field in the plasma exhibits a sudden drop, which coincides in time with a well-defined current pulse. This trend is also predicted by the kinetic model. Analysis of kinetic modeling predictions shows that this effect is caused by large-volume ionization and neutralization of surface charges on the dielectrics by ns discharge pulses. The present

  12. Temperature measurement of an atmospheric pressure arc discharge plasma jet using the diatomic CN (B {sup 2}{sigma}{sup +}-X {sup 2}{sigma}{sup +}, violet system) molecular spectra

    SciTech Connect

    Moon, Se Youn; Kim, D. B.; Gweon, B.; Choe, W.

    2009-03-01

    The CN (B {sup 2}{sigma}{sup +}-X {sup 2}{sigma}{sup +}) molecular emission spectrum is used to measure both the vibrational and rotational temperatures in atmospheric pressure arc jet discharges. The vibrational and rotational temperature effects on the synthetic diatomic molecular spectra were investigated from the (v{sup '},v{sup ''})=(0,0) band to the (5,5) band. The temperatures obtained from the synthetic spectra compared with the experimental result of a low-frequency arc discharge show a vibrational temperature of (4250-5010) K and a rotational temperature of (3760-3980) K for the input power in the range of (80-280) W. As the (0,0) band is isolated from other vibrational transition bands, determination of the rotational temperature is possible based only on the (0,0) band, which simplifies the temperature measurement. From the result, it was found that the CN molecular spectrum can be used as a thermometer for atmospheric pressure plasmas containing carbon and nitrogen.

  13. Discharge lamp technologies

    NASA Technical Reports Server (NTRS)

    Dakin, James

    1994-01-01

    This talk is an overview of discharge lamp technology commonly employed in general lighting, with emphasis on issues pertinent to lighting for plant growth. Since the audience is primarily from the plant growth community, and this begins the light source part of the program, we will start with a brief description of the discharge lamps. Challenges of economics and of thermal management make lamp efficiency a prime concern in controlled environment agriculture, so we will emphasize science considerations relating to discharge lamp efficiency. We will then look at the spectra and ratings of some representative lighting products, and conclude with a discussion of technological advances.

  14. INTENSE ENERGETIC GAS DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-03-01

    A method and apparatus for initiating and sustaining an energetic gas arc discharge are described. A hollow cathode and a hollow anode are provided. By regulating the rate of gas flow into the interior of the cathode, the arc discharge is caused to run from the inner surface of the cathode with the result that adequate space-charge neutralization is provided inside the cathode but not in the main arc volume. Thus, the gas fed to the cathode is substantially completely ionized before it leaves the cathode, with the result that an energetic arc discharge can be maintained at lower operating pressures.

  15. Comparison of circulation times of thermal waters discharging from the Idaho batholith based on geothermometer temperatures, helium concentrations, and 14C measurements

    USGS Publications Warehouse

    Mariner, R.H.; Evans, William C.; Young, H.W.

    2006-01-01

    Circulation times of waters in geothermal systems are poorly known. In this study, we examine the thermal waters of the Idaho batholith to verify whether maximum system temperatures, helium concentrations, and 14C values are related to water age in these low-to-moderate temperature geothermal systems. He/N2 values of gas collected from thermal waters that circulate solely through distinct units of the Idaho batholith correlate linearly with Na-K-(4/3)Ca geothermometer temperatures, showing that both variables are excellent indicators of relative water age. Thermal waters that circulate in early Tertiary (45-50 Ma) granite of the Sawtooth batholith have 3.5 times more helium than thermal waters of the same aquifer temperature that circulate through the main Cretaceous granite (average 91 Ma). Hot spring waters circulating in hydrothermally altered parts of the batholith have very little dissolved helium and no correlation between He/N2 values and geothermometer temperatures. Thermal waters discharging from the Idaho batholith are more depleted in deuterium than modern precipitation in the area. Recharge to these geothermal systems occurred from at least 10,000 BP for the cooler systems up to about 33,000 BP for the hotter systems.

  16. Characterization of Doped Amorphous Silicon Thin Films through the Investigation of Dopant Elements by Glow Discharge Spectrometry. A Correlation of Conductivity and Bandgap Energy Measurements

    PubMed Central

    Sánchez, Pascal; Lorenzo, Olaya; Menéndez, Armando; Menéndez, Jose Luis; Gomez, David; Pereiro, Rosario; Fernández, Beatriz

    2011-01-01

    The determination of optical parameters, such as absorption and extinction coefficients, refractive index and the bandgap energy, is crucial to understand the behavior and final efficiency of thin film solar cells based on hydrogenated amorphous silicon (a-Si:H). The influence of small variations of the gas flow rates used for the preparation of the p-a-SiC:H layer on the bandgap energy, as well as on the dopant elements concentration, thickness and conductivity of the p-layer, is investigated in this work using several complementary techniques. UV-NIR spectrophotometry and ellipsometry were used for the determination of bandgap energies of four p-a-SiC:H thin films, prepared by using different B2H6 and SiH4 fluxes (B2H6 from 12 sccm to 20 sccm and SiH4 from 6 sccm to 10 sccm). Moreover, radiofrequency glow discharge optical emission spectrometry technique was used for depth profiling characterization of p-a-SiC:H thin films and valuable information about dopant elements concentration and distribution throughout the coating was found. Finally, a direct relationship between the conductivity of p-a-SiC:H thin films and the dopant elements concentration, particularly boron and carbon, was observed for the four selected samples. PMID:21731436

  17. Characterization of doped amorphous silicon thin films through the investigation of dopant elements by glow discharge spectrometry: a correlation of conductivity and bandgap energy measurements.

    PubMed

    Sánchez, Pascal; Lorenzo, Olaya; Menéndez, Armando; Menéndez, Jose Luis; Gomez, David; Pereiro, Rosario; Fernández, Beatriz

    2011-01-01

    The determination of optical parameters, such as absorption and extinction coefficients, refractive index and the bandgap energy, is crucial to understand the behavior and final efficiency of thin film solar cells based on hydrogenated amorphous silicon (a-Si:H). The influence of small variations of the gas flow rates used for the preparation of the p-a-SiC:H layer on the bandgap energy, as well as on the dopant elements concentration, thickness and conductivity of the p-layer, is investigated in this work using several complementary techniques. UV-NIR spectrophotometry and ellipsometry were used for the determination of bandgap energies of four p-a-SiC:H thin films, prepared by using different B(2)H(6) and SiH(4) fluxes (B(2)H(6) from 12 sccm to 20 sccm and SiH(4) from 6 sccm to 10 sccm). Moreover, radiofrequency glow discharge optical emission spectrometry technique was used for depth profiling characterization of p-a-SiC:H thin films and valuable information about dopant elements concentration and distribution throughout the coating was found. Finally, a direct relationship between the conductivity of p-a-SiC:H thin films and the dopant elements concentration, particularly boron and carbon, was observed for the four selected samples. PMID:21731436

  18. Potential errors associated with stage-discharge relations for selected streamflow-gaging stations, Maricopa County, Arizona

    USGS Publications Warehouse

    Tillery, Anne C.; Phillips, Jeff V.; Capesius, Joseph P.

    2001-01-01

    Potential errors were derived for individual discharge measurements and stage-discharge relations for 17 streamflow-gaging stations in Maricopa County. Information presented primarily consists of stage and discharge data that were used to develop the stage-discharge relations that were in effect for water year 1998. Accuracy of the discharge measurements directly relate to accuracy of the stage-discharge relation developed for each site. Stage-discharge relations generally are developed using direct measurements of stage and discharge, indirect measurements of peak discharge, and theoretical weir and culvert computations. Accuracy of current-meter measurements of discharge (direct measurements) depends on factors such as the number of subsections in the measurement, stability of the channel, changes in flow conditions, and accuracy of the equipment. Accuracy of indirect measurements of peak discharge is determined by the accuracy of discharge coefficients and flow type selected for the computations. The accuracy of indirect peak-discharge computations generally is less than the accuracy associated with current-meter measurements. Current-meter measurements, indirect measurements of discharge, weir and culvert computations, and step-backwater computations are graphically represented on plots of the stage-discharge relations. Potential errors associated with the discharge measurements at selected sites are depicted as error bars on the plots. Potential errors derived for discharge measurements at 17 sites range from 5 to 25 percent. Errors generally are greater for measurements of large flows in channels having unstable controls using indirect methods.

  19. A dielectric barrier discharge in neon at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Ran, Junxia; Luo, Haiyun; Wang, Xinxin

    2011-08-01

    A dielectric barrier discharge in neon at atmospheric pressure is investigated with electrical measurement and fast photography. It is found that a stable diffuse discharge can be easily generated in a gap with a gap space of 0.5-6 mm and is identified with a glow discharge. The first breakdown voltage of the gap is considerably higher than that of the same gap working in a stable diffuse discharge mode, which indicates that Penning ionization of neon metastables from the previous discharge with inevitable gas impurities plays an important role in the decrease in the breakdown voltage. Discharge patterns are observed in a gap shorter than 1 mm. From the experiments with a wedge-like gap, it is found that the discharge patterns are formed in the area with a higher applied electric field, which suggests that a higher applied electric field may cause a transition from a diffuse glow to discharge patterns.

  20. Lasik eye surgery - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000525.htm Lasik eye surgery - discharge To use the sharing features on this page, please enable JavaScript. Lasik eye surgery permanently changes the shape of the cornea ( ...

  1. Ventriculoperitoneal shunt - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000149.htm Ventriculoperitoneal shunt - discharge To use the sharing features on this ... JavaScript. Your child has hydrocephalus and needed a shunt placed to drain excess fluid and relieve pressure ...

  2. Brain radiation - discharge

    MedlinePlus

    Radiation - brain - discharge; Cancer-brain radiation; Lymphoma - brain radiation; Leukemia - brain radiation ... Decadron) while you are getting radiation to the brain. It may make you hungrier, cause leg swelling ...

  3. Eye muscle repair - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000111.htm Eye muscle repair - discharge To use the sharing features on ... enable JavaScript. You or your child had eye muscle repair surgery to correct eye muscle problems that ...

  4. Carotid artery surgery - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000238.htm Carotid artery surgery - discharge To use the sharing features on this page, please enable JavaScript. You had carotid artery surgery to restore proper blood flow to your ...

  5. Pneumonia - children - discharge

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000011.htm Pneumonia in children - discharge To use the sharing features ... this page, please enable JavaScript. Your child has pneumonia, which is an infection in the lungs. In ...

  6. Pneumonia - adults - discharge

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000017.htm Pneumonia in adults - discharge To use the sharing features on this page, please enable JavaScript. You have pneumonia, which is an infection in your lungs. In ...

  7. Neck dissection - discharge

    MedlinePlus

    ... page: //medlineplus.gov/ency/patientinstructions/000659.htm Neck dissection - discharge To use the sharing features on this page, please enable JavaScript. Neck dissection is surgery to remove the lymph nodes in ...

  8. Asthma - child - discharge

    MedlinePlus

    ... this page: //medlineplus.gov/ency/patientinstructions/000001.htm Asthma - child - discharge To use the sharing features on ... for your child. Take charge of your child's asthma at home Make sure you know the asthma ...

  9. Electrical discharges in air

    NASA Astrophysics Data System (ADS)

    Antanasijević, R.; Banjanac, R.; Dragić, A.; Joković, D.; Joksimović, D.; Marić, Z.; Panić, B.; Udovičić, V.; Vigier, J. P.

    2002-12-01

    An experiment on electrical discharges in air under normal atmospheric conditions has been performed. The ratio between output and input energy is greater than 1, which confirms the results already reported by Graneau et al.

  10. Results of many-year subsatellite measurements of current fine structure in northeastern Black Sea

    NASA Astrophysics Data System (ADS)

    Lavrova, Olga; Krayushkin, Evgeny; Kalashnikova, Nina

    Results of subsatellite measurements of coastal currents in the shelf zone of northeastern Black Sea are presented. The measurements have been performed every year since 2006 in June and September-October months near the Gelendzhik Bay. The main instruments used are Acoustic Doppler Current Profilers (ADCP) and CTD probes. Ground and ship measurements were conducted simultaneously with satellite imaging in microwave (ASAR Envisat, ERS-2, RADARSAT-2, TerraSAR-X), visible and infrared (OLI Landsat-8, ETM+ Landsat-7, TM Landsat-5, MODIS Terra/Aqua, AVHRR NOAA) ranges. The investigations performed revealed spatial, depth and temporal variability of current direction and velocity in the shelf zone. Multiple instances of counter-currents opposing to the Ring Current were registered. In our view, they are associated with a passage of small-scale anticyclonic eddies across the region of interest. The 3D structure of the eddies in the upper quasi-uniform layer was analyzed based on ADCP data. The use of high resolution (3 m) SAR data in combination with ADCP measurements at the resolution of 0.5 m allowed us to detect a number of internal wave trains. Form ADCP and thermistors records, their amplitudes were estimated to reach 5-8 m. Joint analysis of satellite SAR and subsatellite data gave an assessment of their typical wavelength at 90-100 m. Generation mechanisms of these internal waves are suggested. Another phenomenon of interest observed in the region of the measurements is surface manifestations of ring waves near localized natural and anthropogenic generation sources. Such ring waves are most frequently found in the anchor area for ships, whose oscillations can be the source of their generation. The work was in part supported by the Russian Foundation for Basic Research (projects #14-05-00520-а, and 13-07-12017-ofi_m). SAR data from RADARSAT-2 and TerraSAR-X were obtained under SOAR RADARSAT-2/TerraSAR-X Project #5074.

  11. Discharges for lighting

    NASA Astrophysics Data System (ADS)

    Stoffels, W. W.; Nimalasuriya, T.; Flikweert, A. J.; Mulders, H. C. J.

    2007-12-01

    The most common man-made discharge is a lamp. Even though lamps are often considered a mature technology, the discharge physics is often poorly understood. Two recent initiatives discussed here show that plasma research can help to make significant improvements. First we discuss color separation in metal halide lamps, which is a problem that prevents these highly efficient lamps from being used in more applications. Secondly a novel lamp concept is presented that may replace the current mercury based fluorescent lamps.

  12. Low partial discharge vacuum feedthrough

    NASA Technical Reports Server (NTRS)

    Benham, J. W.; Peck, S. R.

    1979-01-01

    Relatively discharge free vacuum feedthrough uses silver-plated copper conductor jacketed by carbon filled silicon semiconductor to reduce concentrated electric fields and minimize occurrence of partial discharge.

  13. TSC simulation of ohmic discharges in TFTR

    SciTech Connect

    Jardin, S.C.; Bell, M.G.; Pomphrey, N.

    1992-04-01

    The Tokamak Simulation Code (TSC) has been used to model the time dependence of several ohmic discharges in the TFTR experiment. We have refined the semi-empirical thermal conductivity model and the sawtooth model in TSC so that good agreement is obtained between the simulation and the experiment in electron and ion temperature profiles, and in the current profiles for the entire duration of the discharges. Neoclassical resistivity gives good agreement with the measured surface voltages and rate of poloidal flux consumption.

  14. The influence of the Kennebec River discharge on estuarine and reverse estuarine flow in eastern Casco Bay, Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Wolovick, M.; Laine, E.; Roesler, C.; Teegarden, G.

    2008-12-01

    Harpswell Sound and the New Meadows estuary are narrow coastal embayments on the eastern side of Casco Bay, in the Gulf of Maine. Hourly oceanographic data was collected at both locations, including ADCP profiles of current velocity vs. depth. It was found that net circulation in both inlets displays both estuarine and inverse estuarine characteristics at various times. During periods of low discharge from the neighboring Kennebec River there is little connection between the two inlets, with New Meadows developing a three- layered circulation regime and Harpswell Sound having periods of negligible net flow punctuated by brief wind-driven events. However, when the discharge of the Kennebec River is high both inlets experience considerable freshening of surface water with corresponding increases in vertical stratification. In addition both inlets act in concert, experiencing near-simultaneous alternation between estuarine and inverse estuarine current regimes of relatively high strength. It is hypothesized that this coordinated reverse estuarine flow is caused by the passage of the leading edge of a bolus of fresher Kennebec discharge past the entrances of the inlets. Water flowing down the sloping surface of this bolus is deflected by the Coriolis force, running into the inlets at the surface and triggering a compensating outflow at depth. Conversely, coordinated estuarine flow is caused by the passage of the trailing edge of the bolus past the entrances, causing the sea surface slope to switch direction.

  15. Dual-RiverSonde measurements of two-dimensional river flow patterns

    USGS Publications Warehouse

    Teague, C.C.; Barrick, D.E.; Lilleboe, P.M.; Cheng, R.T.; Stumpner, P.; Burau, J.R.

    2008-01-01

    Two-dimensional river flow patterns have been measured using a pair of RiverSondes in two experiments in the Sacramento-San Joaquin River Delta system of central California during April and October 2007. An experiment was conducted at Walnut Grove, California in order to explore the use of dual RiverSondes to measure flow patterns at a location which is important in the study of juvenile fish migration. The data available during the first experiment were limited by low wind, so a second experiment was conducted at Threemile Slough where wind conditions and surface turbulence historically have resulted in abundant data. Both experiments included ADCP near-surface velocity measurements from either manned or unmanned boats. Both experiments showed good comparisons between the RiverSonde and ADCP measurements. The flow conditions at both locations are dominated by tidal effects, with partial flow reversal at Walnut Grove and complete flow reversal at Threemile Slough. Both systems showed complex flow patterns during the flow reversals. Quantitative comparisons between the RiverSondes and an ADCP on a manned boat at Walnut Grove showed mean differences of 4.5 cm/s in the u (eastward) and 7.6 cm/s in the v (northward) components, and RMS differences of 14.7 cm/s in the u component and 21.0 cm/s in the v component. Quantitative comparisons between the RiverSondes and ADCPs on autonomous survey vessels at Threemile Slough showed mean differences of 0.007 cm/s in the u component and 0.5 cm/s in the v component, and RMS differences of 7.9 cm/s in the u component and 13.5 cm/s in the v component after obvious outliers were removed. ?? 2008 IEEE.

  16. Shock wave generated by high-energy electric spark discharge

    NASA Astrophysics Data System (ADS)

    Liu, Qingming; Zhang, Yunming

    2014-10-01

    Shock wave generated by electric spark discharge was studied experimentally and the shock wave energy was evaluated in this paper. A pressure measurement system was established to study the pressure field of the electric spark discharge process. A series of electric spark discharge experiments were carried out and the energy of the electric spark used in present study was in the range of 10 J, 100 J, and 1000 J, respectively. The shock wave energy released from the electric spark discharge process was calculated by using the overpressure values at different measurement points near the electric spark discharge center. The good consistency of shock wave energies calculated by pressure histories at different measuring points in the same electric spark discharge experiment illustrates the applicability of the weak shock wave theory in calculating the energy of shock wave induced by electric spark discharge process. The result showed that shock wave formed at the initial stage of electric spark discharge process, and the shock wave energy is only a little part of electric spark energy. From the analysis of the shock wave energy and electric spark energy, a good linear relationship between shock wave energy and electric spark energy was established, which make it possible to calculate shock wave energy by measuring characteristic parameters of electric spark discharge process instead of shock wave. So, the initiation energy of direct initiation of detonation can be determined easily by measuring the parameters of electric spark discharge process.

  17. High power impulse magnetron sputtering discharge

    SciTech Connect

    Gudmundsson, J. T.; Brenning, N.; Lundin, D.; Helmersson, U.

    2012-05-15

    The high power impulse magnetron sputtering (HiPIMS) discharge is a recent addition to plasma based sputtering technology. In HiPIMS, high power is applied to the magnetron target in unipolar pulses at low duty cycle and low repetition frequency while keeping the average power about 2 orders of magnitude lower than the peak power. This results in a high plasma density, and high ionization fraction of the sputtered vapor, which allows better control of the film growth by controlling the energy and direction of the deposition species. This is a significant advantage over conventional dc magnetron sputtering where the sputtered vapor consists mainly of neutral species. The HiPIMS discharge is now an established ionized physical vapor deposition technique, which is easily scalable and has been successfully introduced into various industrial applications. The authors give an overview of the development of the HiPIMS discharge, and the underlying mechanisms that dictate the discharge properties. First, an introduction to the magnetron sputtering discharge and its various configurations and modifications is given. Then the development and properties of the high power pulsed power supply are discussed, followed by an overview of the measured plasma parameters in the HiPIMS discharge, the electron energy and density, the ion energy, ion flux and plasma composition, and a discussion on the deposition rate. Finally, some of the models that have been developed to gain understanding of the discharge processes are reviewed, including the phenomenological material pathway model, and the ionization region model.

  18. Discharge coefficients of impingement and film cooling holes

    NASA Astrophysics Data System (ADS)

    Chu, T.; Brown, A.; Garret, S.

    1985-03-01

    In this article measurements of fluid flow through impingement and film cooling holes for typical turbine blade cooling systems are presented. The purpose of the measurements was to determine hole discharge coefficients over a range of Reynolds numbers from 5,000 to 30,000 and to observe in this range the dependence of discharge coefficient on Reynolds number. The effect of hole geometry, that is, sharp edged inlet or corner radius inlet, on discharge coefficients is also measured. Correlations relating discharge coefficients to Reynolds number, corner radius to hole diameter ratio, and blowing parameter are suggested.

  19. Resource Evaluation and Energy Production Estimate for a Tidal Energy Conversion Installation using Acoustic Flow Measurements

    NASA Astrophysics Data System (ADS)

    Gagnon, Ian; Baldwin, Ken; Wosnik, Martin

    2015-11-01

    The ``Living Bridge'' project plans to install a tidal turbine at Memorial Bridge in the Piscataqua River at Portsmouth, NH. A spatio-temporal tidal energy resource assessment was performed using long term bottom-deployed Acoustic Doppler Current Profilers ADCP. Two locations were evaluated: at the planned deployment location and mid-channel. The goal was to determine the amount of available kinetic energy that can be converted into usable electrical energy on the bridge. Changes in available kinetic energy with ebb/flood and spring/neap tidal cycles and electrical energy demand were analyzed. A system model is used to calculate the net energy savings using various tidal generator and battery bank configurations. Differences in the tidal characteristics between the two measurement locations are highlighted. Different resource evaluation methodologies were also analyzed, e.g., using a representative ADCP ``bin'' vs. a more refined, turbine-geometry-specific methodology, and using static bin height vs. bin height that move w.r.t. the free surface throughout a tidal cycle (representative of a bottom-fixed or floating turbine deployment, respectively). ADCP operating frequencies and bin sizes affect the standard deviation of measurements, and measurement uncertainties are evaluated. Supported by NSF-IIP grant 1430260.

  20. Direct observation of laser guided corona discharges

    NASA Astrophysics Data System (ADS)

    Wang, Tie-Jun; Wei, Yingxia; Liu, Yaoxiang; Chen, Na; Liu, Yonghong; Ju, Jingjing; Sun, Haiyi; Wang, Cheng; Lu, Haihe; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2015-12-01

    Laser based lightning control holds a promising way to solve the problem of the long standing disaster of lightning strikes. But it is a challenging project due to insufficient understanding of the interaction between laser plasma channel and high voltage electric filed. In this work, a direct observation of laser guided corona discharge is reported. Laser filament guided streamer and leader types of corona discharges were observed. An enhanced ionization took place in the leader (filament) through the interaction with the high voltage discharging field. The fluorescence lifetime of laser filament guided corona discharge was measured to be several microseconds, which is 3 orders of magnitude longer than the fluorescence lifetime of laser filaments. This work could be advantageous towards a better understanding of laser assisted leader development in the atmosphere.

  1. Direct observation of laser guided corona discharges

    PubMed Central

    Wang, Tie-Jun; Wei, Yingxia; Liu, Yaoxiang; Chen, Na; Liu, Yonghong; Ju, Jingjing; Sun, Haiyi; Wang, Cheng; Lu, Haihe; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2015-01-01

    Laser based lightning control holds a promising way to solve the problem of the long standing disaster of lightning strikes. But it is a challenging project due to insufficient understanding of the interaction between laser plasma channel and high voltage electric filed. In this work, a direct observation of laser guided corona discharge is reported. Laser filament guided streamer and leader types of corona discharges were observed. An enhanced ionization took place in the leader (filament) through the interaction with the high voltage discharging field. The fluorescence lifetime of laser filament guided corona discharge was measured to be several microseconds, which is 3 orders of magnitude longer than the fluorescence lifetime of laser filaments. This work could be advantageous towards a better understanding of laser assisted leader development in the atmosphere. PMID:26679271

  2. Direct observation of laser guided corona discharges.

    PubMed

    Wang, Tie-Jun; Wei, Yingxia; Liu, Yaoxiang; Chen, Na; Liu, Yonghong; Ju, Jingjing; Sun, Haiyi; Wang, Cheng; Lu, Haihe; Liu, Jiansheng; Chin, See Leang; Li, Ruxin; Xu, Zhizhan

    2015-01-01

    Laser based lightning control holds a promising way to solve the problem of the long standing disaster of lightning strikes. But it is a challenging project due to insufficient understanding of the interaction between laser plasma channel and high voltage electric filed. In this work, a direct observation of laser guided corona discharge is reported. Laser filament guided streamer and leader types of corona discharges were observed. An enhanced ionization took place in the leader (filament) through the interaction with the high voltage discharging field. The fluorescence lifetime of laser filament guided corona discharge was measured to be several microseconds, which is 3 orders of magnitude longer than the fluorescence lifetime of laser filaments. This work could be advantageous towards a better understanding of laser assisted leader development in the atmosphere. PMID:26679271

  3. Model for breakdown process in dielectric discharges

    NASA Technical Reports Server (NTRS)

    Leadon, R.; Wilkenfeld, J.

    1979-01-01

    A heuristic model to explain the blowoff of charge during an electron-induced dielectric discharge is presented. It is proposed that blowoff of charge is initiated by a punchthrough or a flashover. The discharge time is assumed to be governed by an LC time constant where L is the inductance of the electrons flowing in the branches of the Lichtenberg figures at an electron range below the irradiated surface and C is the capacitance between the trapped electrons and the substrate for the discharged area. Experiments to verify that blowoff is a consequence of punchthrough or flashover and to measure the punchthrough current and the variation of discharge time with the sample area and thickness were conducted.

  4. Glow discharge based device for solving mazes

    SciTech Connect

    Dubinov, Alexander E. Mironenko, Maxim S.; Selemir, Victor D.; Maksimov, Artem N.; Pylayev, Nikolay A.

    2014-09-15

    A glow discharge based device for solving mazes has been designed and tested. The device consists of a gas discharge chamber and maze-transformer of radial-azimuth type. It allows changing of the maze pattern in a short period of time (within several minutes). The device has been tested with low pressure air. Once switched on, a glow discharge has been shown to find the shortest way through the maze from the very first attempt, even if there is a section with potential barrier for electrons on the way. It has been found that ionization waves (striations) can be excited in the maze along the length of the plasma channel. The dependancy of discharge voltage on the length of the optimal path through the maze has been measured. A reduction in discharge voltage with one or two potential barriers present has been found and explained. The dependency of the magnitude of discharge ignition voltage on the length of the optimal path through the maze has been measured. The reduction of the ignition voltage with the presence of one or two potential barriers has been observed and explained.

  5. High Power ECR Ion Thruster Discharge Characterization

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Kamhawi, Hani; Haag, Thomas; Carpenter, Christian; Williams, George W.

    2006-01-01

    Electron cyclotron resonance (ECR) based ion thrusters with carbon based ion optics can potentially satisfy lifetime requirements for long duration missions (approximately 10 years) because grid erosion and cathode insert depletion issues are virtually eliminated. Though the ECR plasma discharge has been found to typically operate at slightly higher discharge losses than conventional DC ion thrusters (for high total thruster power applications), the discharge power fraction is small (less than 1 percent at 25 kW). In this regard, the benefits of increased life, low discharge plasma potentials, and reduced complexity are welcome tradeoffs for the associated discharge efficiency decrease. Presented here are results from discharge characterization of a large area ECR plasma source for gridded ion thruster applications. These measurements included load matching efficacy, bulk plasma properties via Langmuir probe, and plasma uniformity as measured using current probes distributed at the exit plane. A high degree of plasma uniformity was observed (flatness greater than 0.9). Additionally, charge state composition was qualitatively evaluated using emission spectroscopy. Plasma induced emission was dominated by xenon ion lines. No doubly charged xenon ions were detected.

  6. Direct current dielectric barrier assistant discharge to get homogeneous plasma in capacitive coupled discharge

    SciTech Connect

    Du, Yinchang; Li, Yangfang; Cao, Jinxiang; Liu, Yu; Wang, Jian; Zheng, Zhe

    2014-06-15

    In this paper, we propose a method to get more homogeneous plasma in the geometrically asymmetric capacitive coupled plasma (CCP) discharge. The dielectric barrier discharge (DBD) is used for the auxiliary discharge system to improve the homogeneity of the geometrically asymmetric CCP discharge. The single Langmuir probe measurement shows that the DBD can increase the electron density in the low density volume, where the DBD electrodes are mounted, when the pressure is higher than 5 Pa. By this manner, we are able to improve the homogeneity of the plasma production and increase the overall density in the target volume. At last, the finite element simulation results show that the DC bias, applied to the DBD electrodes, can increase the homogeneity of the electron density in the CCP discharge. The simulation results show a good agreement with the experiment results.

  7. Measurement of vibrational, gas, and rotational temperatures of H{sub 2} (X{sup 1} {sigma}{sub g}{sup +}) in radio frequency inductive discharge plasma by multiplex coherent anti-Stokes Raman scattering spectroscopy technique

    SciTech Connect

    Shakhatov, V.A.; De Pascale, O.; Capitelli, M.; Hassouni, K.; Lombardi, G.; Gicquel, A.

    2005-02-01

    Translational, rotational, and vibrational temperatures of H{sub 2} in radio frequency inductive discharge plasmas at pressures and power release ranges, respectively, of 0.5-8 torr and 0.5-2 W/cm{sup 3} have been measured by using multiplex coherent anti-Stokes Raman scattering (CARS) spectroscopy. Computational codes have been developed to determine the rotational and vibrational temperatures and to analyze H{sub 2} CARS spectrum for nonequilibrium conditions. The results show a decrease of the vibrational temperature from 4250 to 2800 K by increasing the pressure from 0.5 to 8 torr and a corresponding increase of the rotational temperature from 525 to 750 K.

  8. (Gas discharges and applications)

    SciTech Connect

    Sauers, I.

    1988-10-04

    The traveler attended the Ninth International Conference on Gas Discharges and Their Applications, which was held in Venice, Italy, on September 19--23, 1988; presented two papers, (1) Ion Chemistry in SF{sub 6} Corona'' and (2) Production of S{sub 2}F{sub 10} by SF{sub 6} Spark Discharge''; and participated in numerous discussions with conference participants on gas discharges related to his work on SF{sub 6}. The traveler visited the Centre de Physique Atomique at the University Paul Sabatier in Toulouse, France, to discuss with Dr. J. Casanovas his work on SF{sub 6} decomposition. Following that visit, the traveler visited the Laboratoire de Photoelectricite at the University of Dijon to discuss with Dr. J.-P. Goudonnet his work on surface studies and on the use of tunneling electron spectroscopy for the chemical analysis of surfaces.

  9. Enhanced Discharge Performance in a Ring Cusp Plasma Source

    NASA Technical Reports Server (NTRS)

    Foster, John E.; Patterson, Michael J.

    2000-01-01

    There is a need for a lightweight, low power ion thruster for space science missions. Such an ion thruster is under development at NASA Glenn Research Center. In an effort to better understand the discharge performance of this thruster, a thruster discharge chamber with an anode containing electrically isolated electrodes at the cusps was fabricated and tested. Characteristics of this ring cusp ion discharge were measured without ion beam extraction. Discharge current was measured at collection electrodes located at the magnetic cusps and at the anode body itself. Discharge performance and plasma properties were measured as a function of power, which was varied between 20 and 50 W. It was found that ion production costs decreased by as much as 20 percent when the two most downstream cusp electrodes were allowed to float. Floating the electrodes did not give rise to a significant increase in discharge power even though the plasma density increased markedly. The improved performance is attributed to enhanced electron containment.

  10. Investigating the dependence of the temperature of high-intensity discharge (HID) lamp electrodes on the operating frequency by pyrometric measurements

    NASA Astrophysics Data System (ADS)

    Reinelt, J.; Westermeier, M.; Ruhrmann, C.; Bergner, A.; Awakowicz, P.; Mentel, J.

    2011-03-01

    Phase-resolved temperature distributions are determined along a rod-shaped tungsten electrode, by which an ac arc is operated within a model lamp filled with argon. Switched dc and sinusoidal currents are applied with amplitudes of several amperes and operating frequencies being varied between 10 Hz and 10 kHz. The temperature is deduced from the grey body radiation of the electrode being recorded with a spectroscopic measuring system. Phase-resolved values of the electrode tip temperature Ttip and of the power input Pin are determined comparing the measured temperature distributions with the integral of the one-dimensional heat balance with these parameters as integration constants. They are supplemented by phase-resolved measurements of the sum of cathode and anode fall called the electrode sheath voltage. If a switched dc current is applied it is found that both quantities are within the cathodic phase only marginally higher than for a cathode being operated with a dc current. Ttip and Pin start to decrease for low currents and to increase for high currents at the beginning of the anodic phase. But with increasing operating frequency the deviations from the cathodic phase are reduced until they cannot be resolved for frequencies of several kHz. A more pronounced modulation, but the same tendencies, is observed with a sinusoidal current waveform. For 10 kHz a diffuse arc attachment with an almost phase-independent electrode tip temperature, which deviates only marginally from that of a dc cathode, and an electrode sheath voltage proportional to the arc current is established with both current waveforms.

  11. Comparision of Emissive Probe assisted Measurements of Plasma Density to that of a Surface Wave Probe, in a Dual Frequency Confined Capacitively Coupled Discharge

    NASA Astrophysics Data System (ADS)

    Linnane, S.; Ellingboe, A. R.

    2003-10-01

    Dual frequency confined capacitively coupled plasmas are increasingly used in semiconductor manufacturing for dielectric etching, allowing greater (and independent) control of ion energies and ion flux on the etched substrate. One electrode is driven with the summation of 27MHz and 2MHz sinusoidal voltages, while the other electrode is grounded. The electrode areas are similar in size, giving an electrode aspect ratio less than 2. Because of this low aspect ratio, there are large oscillations in the plasma potential. The expectation is for sinusoidal oscillations at the higher driving frequency, due to capacitive sheaths, while a rectified oscillation is expected at the lower driving frequency [1]. The emissive probe and circuitry allows measurement of plasma potential oscillations at both driving frequencies and their harmonics, thus allowing measurement of the actual time-varying and time-independant plasma potential. Ion saturation current is measured with a single Langmuir probe. Tuned RF filters isolated the probe tip from the external voltage supply (which otherwise acts as a high frequency ground). To further enable the Langmuir probe to follow the plasma potential oscillations, the tip is capacitively coupled to the emissive probe. These results will then be compared with a simple surface wave probe technique [2], which uses the resonant absorption of surface waves by the plasma, to determine plasma density. [1] E. Kawamura, V. Vahedi, M. A. Lieberman and C. K. Birdsall, Plasma Sources Sci. Technology. 8 (1999) R45-R64 [2] Conference proceedings, Frontiers in Low Temperature Plasma Diagnostics V, 2003 pg 30. "Novel Plasma Monitoring by Surface Wave Probe" H.Sugai and K. Nakamura

  12. Brain aneurysm repair - discharge

    MedlinePlus

    ... apply pressure An arm or leg that changes color, becomes cool to touch, or becomes numb Redness, pain, or yellow or green discharge in or around the incision site A fever higher than 101°F (38.3°C) or chills

  13. Longitudinal discharge laser baffles

    DOEpatents

    Warner, B.E.; Ault, E.R.

    1994-06-07

    The IR baffles placed between the window and the electrode of a longitudinal discharge laser improve laser performance by intercepting off-axis IR radiation from the laser and in doing so reduce window heating and subsequent optical distortion of the laser beam. 1 fig.

  14. Longitudinal discharge laser baffles

    DOEpatents

    Warner, Bruce E.; Ault, Earl R.

    1994-01-01

    The IR baffles placed between the window and the electrode of a longitudinal discharge laser improve laser performance by intercepting off-axis IR radiation from the laser and in doing so reduce window heating and subsequent optical distortion of the laser beam.

  15. Discharging older patients.

    PubMed

    2016-09-01

    Significant numbers of older people with dementia use general hospital services, and ensuring the safe and appropriate discharge home of patients with poor cognition, impaired judgement, misperception or reduced risk awareness is complex and challenging for many healthcare professionals. PMID:27615354

  16. Electrical Discharge Machining.

    ERIC Educational Resources Information Center

    Montgomery, C. M.

    The manual is for use by students learning electrical discharge machining (EDM). It consists of eight units divided into several lessons, each designed to meet one of the stated objectives for the unit. The units deal with: introduction to and advantages of EDM, the EDM process, basic components of EDM, reaction between forming tool and workpiece,…

  17. Residual dust charges in discharge afterglow

    SciTech Connect

    Coueedel, L.; Mikikian, M.; Boufendi, L.; Samarian, A. A.

    2006-08-15

    An on-ground measurement of dust-particle residual charges in the afterglow of a dusty plasma was performed in a rf discharge. An upward thermophoretic force was used to balance the gravitational force. It was found that positively charged, negatively charged, and neutral dust particles coexisted for more than 1 min after the discharge was switched off. The mean residual charge for 200-nm-radius particles was measured. The dust particle mean charge is about -5e at a pressure of 1.2 mbar and about -3e at a pressure of 0.4 mbar.

  18. Ionization coefficients for argon in a micro-discharge

    NASA Astrophysics Data System (ADS)

    Kuschel, Thomas; Stefanović, Ilija; Malović, Gordana; Marić, Dragana; Petrović, Zoran Lj

    2013-08-01

    Ionization coefficients are measured for electrons in a dc micro-discharge in argon from optical emission profiles. The micro-discharge is operated in the Townsend regime between two parallel-plate electrodes. Axial profiles of emission are obtained with sufficient resolution to provide spatial ionization coefficients. The measured coefficients agree very well with the data obtained from other sources, indicating the operation of the discharge in the Townsend regime and also that Townsend mechanisms do not need extension to describe such discharges.

  19. Influence of voltage pulse width on the discharge characteristics in an atmospheric dielectric-barrier-discharge plasma jet

    NASA Astrophysics Data System (ADS)

    Uchida, Giichiro; Takenaka, Kosuke; Setsuhara, Yuichi

    2016-01-01

    We present here the analysis of the discharge characteristics of a He dielectric-barrier-discharge (DBD) plasma jet operated in the voltage duty ratio of 20 to 80% under the condition of driving voltage frequency 5 kHz. Discharge strength is sensitive to the voltage pulse width, and the pulse width of 70 µs, which corresponds to the duty ratio of 35%, leads to high O optical emission intensity. We also performed time-resolved optical emission measurements in a transient pulse discharge driven by various voltage duty ratios. Two distinct pulse discharges are observed in the rising and falling periods of the positive rectangular voltage, and the first and second discharges have a peak intensity of optical emission at different duty ratio. The observations indicate that an adequate voltage pulse width could ignite a strong discharge both in the rising and falling period of applied voltage, which could produce a large amount of reactive excited O atoms.

  20. Sediment discharge during floods in eastern Nebraska

    USGS Publications Warehouse

    Mundorff, J.C.

    1962-01-01

    Runoff resulting from rapid melting of a deep snow cover over much of eastern Nebraska resulted in exceptionally high stream stages and in severe flooding on many streams in eastern Nebraska during the latter part of March and the early part of April in 1960. Suspended-sediment concentrations and discharges for most of the streams were somewhat lower than would be expected during similar water discharges that might result from torrential rains rather than snowmelt. During the period March 28-April 8, 1960, when the total water discharge of Platte River at Louisville and of Elkhorn River at Waterloo was about one-fourth of the total for the year, the sediment discharge was an estimated 46 to 50 percent of the estimated total for the year at each station. Both the percentage of sand and the concentration of sand in the suspended sediment were much higher for the Platte and Elkhorn Rivers than for streams in the Big Blue River and Nemaha River basins. For Platte River at Louisville and for Elkhorn River at Waterloo, measured sediment discharges ranged from about 87 to 94 percent of the computed total sediment discharge.

  1. Discharge Estimation Using Hydro-Geodetic Approaches

    NASA Astrophysics Data System (ADS)

    Lorenz, C.; Tourian, M. J.; Devaraju, B.; Riegger, J. M.; Kunstmann, H.; Sneeuw, N. J.

    2014-12-01

    The publicly available global discharge database is limited in spatial and temporal coverage. Although regional exceptions exist, the population of the database has declined over the past several years. When aiming for global scale discharge at a sufficient temporal resolution and with homogeneous accuracy, the choice to use spaceborne sensors is only a logical step. In this respect, we take water storage changes from GRACE and water level measurements from satellite altimetry and present a comprehensive assessment of 5 different hydro-geodetic approaches for river discharge prediction: hydrological balance equation, hydro-meteorological balance equation, least squares prediction using the covariance matrices out of available old in situ data, satellite altimetry with quantile function based stage-discharge relationships and a runoff-storage relationship that takes time-lag into account. As a common property these approaches do not rely on hydrological modeling; they are either purely data driven or make use of atmospheric reanalyses. The discharge estimation skill of these approaches are validated against in situ data. Our validation shows that satellite altimetry, runoff-storage and least squares prediction approaches are able to capture river discharge with an error range (relative RMSE) of less than 15% for most of the rivers under study. We are thus able to avoid the complexity of hydrological modeling for discharge estimation. Our results show that the mentioned three approaches clearly outperform the global methods (hydrological and hydro-meteorological approaches). However, the global methods have the potential to provide discharge over all landmasses ---gauged and ungauged basins alike, but are still limited due to inconsistencies in the global hydrological and hydro-meteorological datasets that they use.

  2. Field Measurements to Characterize Turbulent Inflow for Marine Hydrokinetic Devices - Marrowstone Island, WA

    NASA Astrophysics Data System (ADS)

    Richmond, M. C.; Thomson, J. M.; Durgesh, V.; Polagye, B. L.

    2011-12-01

    Field measurements are essential for developing an improved understanding of turbulent inflow conditions that affect the design and operation of marine and hydrokinetic (MHK) devices. The Marrowstone Island site in Puget Sound, Washington State is a potential location for installing MHK devices, as it experiences strong tides and associated currents. Here, field measurements from Nodule Point on the eastern side of Marrowstone Island are used to characterize the turbulence in terms of velocity variance as a function of length and time scales. The field measurements were performed using Acoustic Doppler Velocimetry (ADV) and Acoustic Doppler Current Profiler (ADCP) instruments. Both were deployed on a bottom-mounted tripod at the site by the Applied Physics Lab at the University of Washington (APL-UW). The ADV acquired single point, temporally resolved velocity data from 17-21 Feb 2011, at a height of 4.6 m above the seabed at a sampling frequency of 32 Hz. The ADCP measured the velocity profile over the water column from a height of 2.6 m above the seabed up to the sea-surface in 36 bins, with each bin of 0.5 m size. The ADCP acquired data from 11-27 Feb 2011 at a sampling frequency of 2 Hz. Analysis of the ADV measurements shows distinct dynamic regions by scale: anisotropic eddies at large scales, an isotropic turbulent cascade (-5/3 slope in frequency spectra) at mesoscales, and contamination by Doppler noise at small scales. While Doppler noise is an order of magnitude greater for the ADCP measurements, the turbulence bulk statistics are consistent between the two instruments. There are significant variations in turbulence statistics with stage of the tidal currents (i.e., from slack to non-slack tidal conditions), however an average turbulent intensity of 10% is a robust, canonical value for this site. The ADCP velocity profiles are useful in quantifying the variability in velocity along the water column, and the ensemble averaged velocity profiles may be

  3. Time-averaged discharge rate of subaerial lava at Kīlauea Volcano, Hawai‘i, measured from TanDEM-X interferometry: Implications for magma supply and storage during 2011-2013

    USGS Publications Warehouse

    Poland, Michael P.

    2014-01-01

    Differencing digital elevation models (DEMs) derived from TerraSAR add-on for Digital Elevation Measurements (TanDEM-X) synthetic aperture radar imagery provides a measurement of elevation change over time. On the East Rift Zone (EZR) of Kīlauea Volcano, Hawai‘i, the effusion of lava causes changes in topography. When these elevation changes are summed over the area of an active lava flow, it is possible to quantify the volume of lava emplaced at the surface during the time spanned by the TanDEM-X data—a parameter that can be difficult to measure across the entirety of an ~100 km2 lava flow field using ground-based techniques or optical remote sensing data. Based on the differences between multiple TanDEM-X-derived DEMs collected days to weeks apart, the mean dense-rock equivalent time-averaged discharge rate of lava at Kīlauea between mid-2011 and mid-2013 was approximately 2 m3/s, which is about half the long-term average rate over the course of Kīlauea's 1983–present ERZ eruption. This result implies that there was an increase in the proportion of lava stored versus erupted, a decrease in the rate of magma supply to the volcano, or some combination of both during this time period. In addition to constraining the time-averaged discharge rate of lava and the rates of magma supply and storage, topographic change maps derived from space-based TanDEM-X data provide insights into the four-dimensional evolution of Kīlauea's ERZ lava flow field. TanDEM-X data are a valuable complement to other space-, air-, and ground-based observations of eruptive activity at Kīlauea and offer great promise at locations around the world for aiding with monitoring not just volcanic eruptions but any hazardous activity that results in surface change, including landslides, floods, earthquakes, and other natural and anthropogenic processes.

  4. Relating river discharges to salinity changes

    NASA Astrophysics Data System (ADS)

    Xie, X.; Liu, W. T.

    2014-12-01

    New river discharge data are brought together with spacebased sea surface salinity measurements by Aquarius and SMOS to demonstrate the role of river discharge in salinity changes near three river mouths: the Mississippi, the Ganges, and the Amazon. The characteristics of the seasonal cycle and the year-to-year changes of the river runoff are described. Various versions of the satellite salinity data are compared. The relative roles of river discharge, surface water flux, and horizontal advection in changing surface salinity in regions near the river mouths are examined. Satellite measurements of SSS clearly track movements of the fresh water from river discharges. Besides the river discharge, E-P plays an important role in the seasonal salinity variation near the Ganges and Irrawaddy River mouths. For the Mississippi and Amazon river mouths, central and eastern ITCZ, E-P contributes very little to the salinity seasonal change. In the central and eastern ITCZ, contribution of advection to the salinity tendency is clearly identified. Both salinity and salinity tendency are dominated by semi-annual cycle in the Atlantic ITCZ between 5ºN to 9ºN, whereas annual cycle dominates at other latitudes.

  5. Discharge pulse phenomenology

    NASA Technical Reports Server (NTRS)

    Frederickson, A. R.

    1985-01-01

    A model was developed which places radiation induced discharge pulse results into a unified conceptual framework. Only two phenomena are required to interpret all space and laboratory results: (1) radiation produces large electrostatic fields inside insulators via the trapping of a net space charge density; and (2) the electrostatic fields initiate discharge streamer plasmas similar to those investigated in high voltage electrical insulation materials; these streamer plasmas generate the pulsing phenomena. The apparent variability and diversity of results seen is an inherent feature of the plasma streamer mechanism acting in the electric fields which is created by irradiation of the dielectrics. The implications of the model are extensive and lead to constraints over what can be done about spacecraft pulsing.

  6. Discharge borders wars

    SciTech Connect

    Sweeney, N.J. )

    1991-05-01

    This article discusses the impact of a downstream state's standards on the application for a National Pollutant Discharge Elimination System (NPDES) permit by a downstream state as recently explained in a federal court of appeals decision. The litigation discussed included the EPA and the states of Oklahoma and Arkansas. Topics covered include a description of the situation that brought about the litigation, the initial ruling by the EPA and the federal court's reasoning for the final outcome.

  7. Hydrogen discharges operating at atmospheric pressure in a semiconductor gas discharge system

    NASA Astrophysics Data System (ADS)

    Aktas, K.; Acar, S.; Salamov, B. G.

    2011-08-01

    Analyses of physical processes which initiate electrical breakdown and spatial stabilization of current and control it with a photosensitive cathode in a semiconductor gas discharge system (SGDS) are carried out in a wide pressure range up to atmospheric pressure p, interelectrode distance d and diameter D of the electrode areas of the semiconductor cathode. The study compares the breakdown and stability curves of the gas discharge in the planar SGDS where the discharge gap is filled with hydrogen and air in two cases. The impact of the ionizing component of the discharge plasma on the control of the stable operation of the planar SGDS is also investigated at atmospheric pressure. The loss of stability is primarily due to modification of the semiconductor-cathode properties on the interaction with low-energy hydrogen ions and the formation of a space charge of positive ions in the discharge gap which changes the discharge from Townsend to glow type. The experimental results show that the discharge current in H2 is more stable than in air. The breakdown voltages are measured for H2 and air with parallel-plane electrodes, for pressures between 28 and 760 Torr. The effective secondary electron emission (SEE) coefficient is then determined from the breakdown voltage results and compared with the experimental results. The influence of the SEE coefficient is stated in terms of the differences between the experimental breakdown law.

  8. Powerful glow discharge excilamp

    DOEpatents

    Tarasenko, Victor F.; Panchenko, Aleksey N.; Skakun, Victor S.; Sosnin, Edward A.; Wang, Francis T.; Myers, Booth R.; Adamson, Martyn G.

    2002-01-01

    A powerful glow discharge lamp comprising two coaxial tubes, the outer tube being optically transparent, with a cathode and anode placed at opposite ends of the tubes, the space between the tubes being filled with working gas. The electrodes are made as cylindrical tumblers placed in line to one other in such a way that one end of the cathode is inserted into the inner tube, one end of the anode coaxially covers the end of the outer tube, the inner tube penetrating and extending through the anode. The increased electrodes' surface area increases glow discharge electron current and, correspondingly, average radiation power of discharge plasma. The inner tube contains at least one cooling liquid tube placed along the axis of the inner tube along the entire lamp length to provide cathode cooling. The anode has a circumferential heat extracting radiator which removes heat from the anode. The invention is related to lighting engineering and can be applied for realization of photostimulated processes under the action of powerful radiation in required spectral range.

  9. Modeling electronegative plasma discharge

    SciTech Connect

    Lichtenberg, A.J.; Lieberman, M.A.

    1995-12-31

    Macroscopic analytic models for a three-component electronegative gas discharge are developed. Assuming the negative ions to be in Boltzmann equilibrium, a positive ion ambipolar diffusion equation is derived. The discharge consists of an electronegative core and electropositive edges. The electron density in the core is nearly uniform, allowing a parabolic approximation to the plasma profile to be employed. The resulting equilibrium equations are solved analytically and matched to a constant mobility transport model of an electropositive edge plasma. The solutions are compared to a simulation of a parallel-plane r.f. driven oxygen plasma for p = 50 mTorr and n{sub eo}= 2.4 x 10{sup 15} m{sup -3}. The ratio {alpha}{sub o} of central negative ion density to electron density, and the electron temperature T{sub e}, found in the simulation, are in reasonable agreement with the values calculated from the model. The model is extended to: (1) low pressures, where a variable mobility model is used in the electropositive edge region; and (2) high {alpha}{sub o} in which the edge region disappears. The inclusion of a second positive ion species, which can be very important in describing electronegative discharges used for materials processing, is a possible extension of the model.

  10. Physics of helicon discharges

    SciTech Connect

    Chen, F.F.

    1996-05-01

    Because of their high density, low-pressure discharges ionized by helicon waves are being studied for their possible use in cluster tools for the fabrication of next-generation computer chips. How helicon waves are related to whistler waves and waves in a plasma-filled waveguide is explained, and the mystery of the high ionization efficiency is outlined. Experimental data on the waves and the equilibrium properties of the discharge are shown, and the status of our current understanding of the physical processes therein is summarized. The importance of kinetic effects and of a short-wavelength mode arising at low magnetic fields is evaluated. Applications of helicon discharges to such diverse fields as plasma accelerators, microwave generators, and tokamak physics are illustrated. Low-temperature plasma physics is often considered a discipline so different from high-temperature plasma physics that there is little overlap, but these studies show that the techniques developed in fusion and space plasma physics can be applied to technological plasmas as well. {copyright} {ital 1996 American Institute of Physics.}

  11. Autonomous Method and System for Minimizing the Magnitude of Plasma Discharge Current Oscillations in a Hall Effect Plasma Device

    NASA Technical Reports Server (NTRS)

    Hruby, Vladimir (Inventor); Demmons, Nathaniel (Inventor); Ehrbar, Eric (Inventor); Pote, Bruce (Inventor); Rosenblad, Nathan (Inventor)

    2014-01-01

    An autonomous method for minimizing the magnitude of plasma discharge current oscillations in a Hall effect plasma device includes iteratively measuring plasma discharge current oscillations of the plasma device and iteratively adjusting the magnet current delivered to the plasma device in response to measured plasma discharge current oscillations to reduce the magnitude of the plasma discharge current oscillations.

  12. Hydrokinetic canal measurements: inflow velocity, wake flow velocity, and turbulence

    DOE Data Explorer

    Gunawan, Budi

    2014-06-11

    The dataset consist of acoustic Doppler current profiler (ADCP) velocity measurements in the wake of a 3-meter diameter vertical-axis hydrokinetic turbine deployed in Roza Canal, Yakima, WA, USA. A normalized hub-centerline wake velocity profile and two cross-section velocity contours, 10 meters and 20 meters downstream of the turbine, are presented. Mean velocities and turbulence data, measured using acoustic Doppler velocimeter (ADV) at 50 meters upstream of the turbine, are also presented. Canal dimensions and hydraulic properties, and turbine-related information are also included.

  13. The influence of deep groundwater discharge on spatial variability of stream discharge and chemistry

    NASA Astrophysics Data System (ADS)

    Egusa, T.; Ohte, N.; Oda, T.; Obara, A.; Suzuki, M.

    2011-12-01

    In forest catchments, large amounts of groundwater infiltrate and pass through bedrock. This deep groundwater has a long residence time, as well as high concentrations of minerals that originate from dissolved matter. Thus, deep groundwater has a great influence on stream discharge and chemistry. However, in small catchments, stream discharge and chemistry vary greatly, even in geologically homogeneous catchments. The representative elementary area (REA) concept proposed by Wood defines the REA as a threshold area, beyond which an average hydrologic response occurs. Extensive research has shown that different catchments have different REA values. However, the factors that determine the REA value and the effect of deep groundwater on the REA are not yet clear. Hence, our objective was to elucidate the influence of deep groundwater discharge on the spatial variability of stream discharge, chemistry, and REA value. Our study site was the Inokawa catchment in Japan. The steep, forested catchment area was 5 km2. Inokawa is underlain by a Tertiary formation of sedimentary rock. In one zero-order hollow in Inokawa, large amounts of water (annual average 520 mm) infiltrate bedrock. We measured stream discharge and sampled stream water, which was then analyzed using ion chromatography. In small catchments, all solute concentrations and specific discharges have large spatial variability. As the catchment area increases, variability decreases. We found a convergence of NO3-,Mg2+,Ca2+,SO42- above 1-2 km2 and confirmed the existence of an REA. However, other dissolved matter and specific discharge did not converge to certain values and increased at 3-5 km2. Thus, we could not confirm the existence of an REA at these distances. We used the End Members Mixing Analysis(EMMA) method, separating stream water into three components: soil water, groundwater, and deep groundwater. The soil water component did not show a quantitative change above 1 km2. In contrast, groundwater and deep

  14. Development of a new corona discharge based ion source for high resolution time-of-flight chemical ionization mass spectrometer to measure gaseous H2SO4 and aerosol sulfate

    NASA Astrophysics Data System (ADS)

    Zheng, Jun; Yang, Dongsen; Ma, Yan; Chen, Mindong; Cheng, Jin; Li, Shizheng; Wang, Ming

    2015-10-01

    A new corona discharge (CD) based ion source was developed for a commercial high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS) (Aerodyne Research Inc.) to measure both gaseous sulfuric acid (H2SO4) and aerosol sulfate after thermal desorption. Nitrate core ions (NO3-) were used as reagent ions and were generated by a negative discharge in zero air followed by addition of excess nitrogen dioxide (NO2) to convert primary ions and hydroxyl radicals (OH) into NO3- ions and nitric acid (HNO3). The CD-HRToF-CIMS showed no detectable interference from hundreds parts per billion by volume (ppbv) of sulfur dioxide (SO2). Unlike the atmospheric pressure ionization (API) ToF-CIMS, the CD ion source was integrated onto the ion-molecule reaction (IMR) chamber and which made it possible to measure aerosol sulfate by coupling to a filter inlet for gases and aerosols (FIGAERO). Moreover, compared with a quadrupole-based mass spectrometer, the desired HSO4- signal was detected by its exact mass of m/z 96.960, which was well resolved from the potential interferences of HCO3-ṡ(H2O)2 (m/z 97.014) and O-ṡH2OṡHNO3 (m/z 97.002). In this work, using laboratory-generated standards the CD-HRToF-CIMS was demonstrated to be able to detect as low as 3.1 × 105 molecules cm-3 gaseous H2SO4 and 0.5 μg m-3 ammonium sulfate based on 10-s integration time and two times of the baseline noise. The CD ion source had the advantages of low cost and a simple but robust structure. Since the system was non-radioactive and did not require corrosive HNO3 gas, it can be readily field deployed. The CD-HRToF-CIMS can be a powerful tool for both field and laboratory studies of aerosol formation mechanism and the chemical processes that were critical to understand the evolution of aerosols in the atmosphere.

  15. Plasma Discharge Process in a Pulsed Diaphragm Discharge System

    NASA Astrophysics Data System (ADS)

    Duan, Jianjin; Hu, Jue; Zhang, Chao; Wen, Yuanbin; Meng, Yuedong; Zhang, Chengxu

    2014-12-01

    As one of the most important steps in wastewater treatment, limited study on plasma discharge process is a key challenge in the development of plasma applications. In this study, we focus on the plasma discharge process of a pulsed diaphragm discharge system. According to the analysis, the pulsed diaphragm discharge proceeds in seven stages: (1) Joule heating and heat exchange stage; (2) nucleated site formation; (3) plasma generation (initiation of the breakdown stage); (4) avalanche growth and plasma expansion; (5) plasma contraction; (6) termination of the plasma discharge; and (7) heat exchange stage. From this analysis, a critical voltage criterion for breakdown is obtained. We anticipate this finding will provide guidance for a better application of plasma discharges, especially diaphragm plasma discharges.

  16. Silo collapse under granular discharge.

    PubMed

    Gutiérrez, G; Colonnello, C; Boltenhagen, P; Darias, J R; Peralta-Fabi, R; Brau, F; Clément, E

    2015-01-01

    We investigate, at a laboratory scale, the collapse of cylindrical shells of radius R and thickness t induced by a granular discharge. We measure the critical filling height for which the structure fails upon discharge. We observe that the silos sustain filling heights significantly above an estimation obtained by coupling standard shell-buckling and granular stress distribution theories. Two effects contribute to stabilize the structure: (i) below the critical filling height, a dynamical stabilization due to granular wall friction prevents the localized shell-buckling modes to grow irreversibly; (ii) above the critical filling height, collapse occurs before the downward sliding motion of the whole granular column sets in, such that only a partial friction mobilization is at play. However, we notice also that the critical filling height is reduced as the grain size d increases. The importance of grain size contribution is controlled by the ratio d/√[Rt]. We rationalize these antagonist effects with a novel fluid-structure theory both accounting for the actual status of granular friction at the wall and the inherent shell imperfections mediated by the grains. This theory yields new scaling predictions which are compared with the experimental results. PMID:25615503

  17. Interoperability challenges in river discharge modelling

    NASA Astrophysics Data System (ADS)

    Santoro, Mattia; Schlummer, Manuela; Andres, Volker; Jirka, Simon; Looser, Ulrich; Mladek, Richard; Pappenberger, Florian; Strauch, Adrian; Utech, Michael; Zsoter, Ervin

    2014-05-01

    River discharge is a critical water cycle variable, as it integrates all the processes (e.g. runoff and evapotranspiration) occurring within a river basin and provides a hydrological output variable that can be readily measured. Its prediction is of invaluable help for many water-related areas such as water resources assessment and management, as well as flood protection and disaster mitigation. Observations of river discharge are very important for the calibration and validation of hydrological or coupled land, atmosphere and ocean models . This requires the use of data from different scientific domains (Water, Weather, etc.). Typically, such data are provided using different technological solutions and formats. This complicates the integration of new hydrological data sources into application systems. Therefore, a considerable effort is often spent on data access issues instead of the actual scientific question. In the context of the FP7 funded project GEOWOW (GEOSS Interoperability for Weather, Ocean and Water), the "River Discharge" use scenario was developed in order to combine river discharge observations data from the Global Runoff Data Center (GRDC) database and model outputs produced by the European Centre for Medium-Range Weather Forecasts (ECMWF) predicting river discharge based on weather forecast information. In this presentation we describe interoperability solutions which were adopted in order to address the technological challenges of the "River Discharge" use scenario: 1) Development of a Hydrology Profile for the OGC SOS 2.0 standard; 2) Enhancement of the GEO DAB (Discovery and Access Broker) to support the use scenario: 2.1) Develop new interoperability arrangements for GRDC and ECMWF capacities; 2.2) Select multiple time series for comparison. The development of the above functionalities and tools aims to respond to the need of Water and Weather scientists to assess river discharge forecasting models.

  18. Diel vertical migrations of Meganyctiphanes norvegica in the Kattegat: Comparison of net catches and measurements with Acoustic Doppler Current Profilers

    NASA Astrophysics Data System (ADS)

    Buchholz, F.; Buchholz, C.; Reppin, J.; Fischer, J.

    1995-03-01

    Diel vertical migration of a stable and well-defined population of Nordic krill, Meganyctiphanes norvegica (Crustacea, Euphausiacea) was investigated during eight days in August 1989, in the Läsö-Deep, East of the Danish island Läsö. Net catches with a multi-net (MOCNESS) and measurements with a moored and a shipboard Acoustic Doppler Current Profiler (ADCP) were compared. Backscattered energy as a measure for biomass gave good correlations to the dry weight of M. norvegica and smaller zooplankton from net catches. Diel migratory patterns matched well, as determined, parallel with both methods. Migratory vertical velocity was determined with ADCP at 2 3 cm sec-1. The potential for the use of ADCPs for biological investigation is discussed. Vertical migration was dependent on environmental parameters. The krill did not cross a temperature barrier of 14°C, although rich food sources were situated beyond it. Differences in salinity did not play a role. Currents were involved in plankton distribution. Light was an important Zeitgeber (synchronizer) and determined the density of the krill aggregations. Feeding behaviour did not interfere with the light-induced migratory pattern of Nordic krill at the Läsö-Deep.

  19. Operation of Ferroelectric Plasma Sources in a Gas Discharge Mode

    SciTech Connect

    A. Dunaevsky; N.J. Fisch

    2004-03-08

    Ferroelectric plasma sources in vacuum are known as sources of ablative plasma, formed due to surface discharge. In this paper, observations of a gas discharge mode of operation of the ferroelectric plasma sources (FPS) are reported. The gas discharge appears at pressures between approximately 20 and approximately 80 Torr. At pressures of 1-20 Torr, there is a transition from vacuum surface discharge to the gas discharge, when both modes coexist and the surface discharges sustain the gas discharge. At pressures between 20 and 80 Torr, the surface discharges are suppressed, and FPS operate in pure gas discharge mode, with the formation of almost uniform plasma along the entire surface of the ceramics between strips. The density of the expanding plasma is estimated to be about 1013 cm-3 at a distance of 5.5 mm from the surface. The power consumption of the discharge is comparatively low, making it useful for various applications. This paper also presents direct measurements of the yield of secondary electron emission from ferroelectric ceramics, which, at low energies of primary electrons, is high and dependent on the polarization of the ferroelectric material

  20. Corona discharge influences ozone concentrations near rats.

    PubMed

    Goheen, Steven C; Gaither, Kari; Anantatmula, Shantha M; Mong, Gary M; Sasser, Lyle B; Lessor, Delbert

    2004-02-01

    Ozone can be produced by corona discharge either in dry air or when one electrode is submerged in water. Since ozone is toxic, we examined whether ozone production by corona near laboratory animals could reach levels of concern. Male rats were exposed to a corona discharge and the concentration of ozone produced was measured. The resulting concentration of ozone ranged from ambient levels to 250 ppb when animals were located 1 cm from a 10 kV source. Similar ozone concentrations were observed when a grounded water source was present. Possible explanations for, as well as concerns regarding, ozone production under these conditions are discussed. PMID:14735560