Science.gov

Sample records for ac electrical measurements

  1. Measurement of AC electrical characteristics of SSC superconducting dipole magnets

    SciTech Connect

    Smedley, K M; Shafer, R E

    1992-01-01

    Experiments were conducted to measure the AC electrical characteristics of SSC superconducting dipole magnets over the frequency range of 0.1 Hz to 10 kHz. A magnet equivalent circuit representing the magnet DC inductance, eddy current losses, coil-to-ground and turn-to-turn capacitance, was synthesized from the experimental data. This magnet equivalent circuit can be used to predict the current ripple distribution along the superconducting magnet string and can provide dynamic information for the design of the collider current regulation loop.

  2. DC and AC Electric Field Measurements by Spin-Plane Double Probes Onboard MMS

    NASA Astrophysics Data System (ADS)

    Lindqvist, P. A.; Marklund, G. T.; Khotyaintsev, Y. V.; Ergun, R. E.; Goodrich, K.; Torbert, R. B.; Argall, M. R.; Nakamura, R.

    2015-12-01

    The four spacecraft of the NASA Magnetospheric Multiscale mission (MMS) were launched on 12 March 2015 into a 1.2 x 12 Re equatorial orbit to study energy conversion processes in Earth's magnetosphere. After a 5-month commissioning period the first scientific phase starts on 1 September as the orbit enters the dusk magnetopause region. The Spin-plane Double Probe electric field instrument (SDP), part of the electric and magnetic fields instrument suite FIELDS, measures the electric field in the range 0.3 - 500 mV/m with a continuous time resolution up to 8192 samples/s. The instrument features adjustable bias currents and guard voltages to optimize the measurement performance. SDP also measures the spacecraft potential, which can be controlled by the Active Spacecraft Potential Control (ASPOC) ion emitter, and under certain conditions can be used to determine plasma density. We present observations of DC and AC electric fields in different plasma regions covered by MMS since launch including the night side flow braking region, reconnection regions at the dusk and dayside magnetopause, and in the magnetosheath. We compare the electric field measurements by SDP to other, independent determinations of the electric field, in particular by the Electron Drift Instrument (EDI), in order to assess the accuracy of the electric field measurement under different plasma conditions. We also study the influence of the currents emitted by ASPOC and EDI on the SDP measurements.

  3. Electrical resistivity and AC-calorimetric measurements of PrRu 4P 12 under pressure

    NASA Astrophysics Data System (ADS)

    Miyake, A.; Holmes, A. T.; Kagayama, T.; Shimizu, K.; Sekine, C.; Shirotani, I.; Kikuchi, D.; Sugawara, H.; Sato, H.

    2008-04-01

    We have studied the effect of pressure in the filled skutterudite PrRu 4P 12, which shows a metal-insulator (MI) transition at TMI=63 K, via simultaneous measurements of electrical resistivity ( ρ) and AC-calorimetry ( CAC). Schottky-like anomalies in CAC disappear under pressure, suggesting a change of the ground state. The resistivity below TMI is strongly suppressed with increasing pressure, in contrast to the weak pressure dependence of TMI. Above 10 GPa, ρ(T) shows metallic behavior with small anomalies at TMI. We discuss the likely change of ground state in PrRu 4P 12 with pressure from triplet to singlet.

  4. Spectral response of atmospheric electric field measurements near AC high voltage power lines

    NASA Astrophysics Data System (ADS)

    Silva, H. G.; Matthews, J. C.; Wright, M. D.; Shallcross, D. E.

    2015-10-01

    To understand the influence of corona ion emission on the atmospheric electrical field, measurements were made near to two AC high voltage power lines. A JCI 131 field-mill recorded the atmospheric electric field over one year. Meteorological measurements were also taken. The data series is divided in four zones (dependent on wind direction): whole zones, Z0; zone 1, Z1; zone 2, Z2; zone 3, Z3. Z3 is the least affected by corona ion emission and for that reason it is used as a reference against Z1 and Z2, which are strongly influenced by this phenomena. Analysis was undertaken for all weather days and dry days only. The Lomb-Scargle strategy developed for unevenly spaced time-series is used to calculate the spectral response of the aforementioned zones. Only frequencies above 1 minute are considered.

  5. AC resistance measuring instrument

    DOEpatents

    Hof, P.J.

    1983-10-04

    An auto-ranging AC resistance measuring instrument for remote measurement of the resistance of an electrical device or circuit connected to the instrument includes a signal generator which generates an AC excitation signal for application to a load, including the device and the transmission line, a monitoring circuit which provides a digitally encoded signal representing the voltage across the load, and a microprocessor which operates under program control to provide an auto-ranging function by which range resistance is connected in circuit with the load to limit the load voltage to an acceptable range for the instrument, and an auto-compensating function by which compensating capacitance is connected in shunt with the range resistance to compensate for the effects of line capacitance. After the auto-ranging and auto-compensation functions are complete, the microprocessor calculates the resistance of the load from the selected range resistance, the excitation signal, and the load voltage signal, and displays of the measured resistance on a digital display of the instrument. 8 figs.

  6. AC Resistance measuring instrument

    DOEpatents

    Hof, Peter J.

    1983-01-01

    An auto-ranging AC resistance measuring instrument for remote measurement of the resistance of an electrical device or circuit connected to the instrument includes a signal generator which generates an AC excitation signal for application to a load, including the device and the transmission line, a monitoring circuit which provides a digitally encoded signal representing the voltage across the load, and a microprocessor which operates under program control to provide an auto-ranging function by which range resistance is connected in circuit with the load to limit the load voltage to an acceptable range for the instrument, and an auto-compensating function by which compensating capacitance is connected in shunt with the range resistance to compensate for the effects of line capacitance. After the auto-ranging and auto-compensation functions are complete, the microprocessor calculates the resistance of the load from the selected range resistance, the excitation signal, and the load voltage signal, and displays of the measured resistance on a digital display of the instrument.

  7. Electrical Effect in Silver-Point Realization Due to Cell Structure and Bias Voltage Based on Resistance Measurement Using AC and DC Bridges

    NASA Astrophysics Data System (ADS)

    Widiatmo, J. V.; Harada, K.; Yamazawa, K.; Tamba, J.; Arai, M.

    2015-08-01

    Electrical effects related to insulating leakage represent one of the major factors contributing to uncertainties in measurements using high-temperature standard platinum resistance thermometers (HTSPRTs), especially during the realization of the silver freezing point (). This work is focused on the evaluation of the differences in resistance measurements observed when using AC resistance bridges and DC resistance bridges, hereafter, termed the AC-DC differences, as the result of various electrical effects. The magnitude of the AC-DC difference in several silver-point cells is demonstrated with several HTSPRTs. The effect of the cell structure on the AC-DC difference is evaluated by exchanging some components, part by part, within a silver-point cell. Then, the effect of the bias voltage applied to the heat pipe within the silver-point furnace is evaluated. Through the analysis of the experimental results and comparison with the reports in the literature, the importance of evaluating the AC-DC difference as a means to characterize the underlying electrical effects is discussed, considering that applying a negative bias condition to the furnace with respect to the high-temperature SPRT can minimize the AC-DC difference. Concluding recommendations are proposed on the components used in silver-point cells and the application of a bias voltage to the measurement circuit to minimize the effects of the electrical leakage.

  8. Optical, electrical and ac conductivity measurements of nonlinear optical Dimethylaminomethylphthalimide doped with cadmium chloride single crystal for nano applications

    NASA Astrophysics Data System (ADS)

    Subramani, K.; Joseph, P. S.; Shankar, G.

    2013-07-01

    Single crystals of Dimethylaminomethylphthalimide cadmium chloride (DAMPCC) were grown by a slow evaporation technique. The unit cell parameters and crystal structure were measured by the powder X-ray diffraction analysis. The modes of vibrations of different molecular groups present in the DAMPCC crystal have been identified by FTIR spectral analysis. The UV-vis-NIR spectral analysis is used to study the optical behaviors like absorption and transmission properties of the crystal. The diffuse reflectance spectrum in absorption studies is calculated. The optical band gap of the DAMPCC crystal is calculated to be cut off wavelength 360 nm at photon energy 4.772 eV. The optical conductivity, electrical conductivity and ac conductivity are also calculated. Finally the nonlinear optics (NLO) property of DAMPCC crystal was confirmed by second harmonic generation (SHG) test using the Nd:YAG laser of fundamental wavelength 1064 nm.

  9. ac-resistance-measuring instrument

    SciTech Connect

    Hof, P.J.

    1981-04-22

    An auto-ranging ac resistance measuring instrument for remote measurement of the resistance of an electrical device or circuit connected to the instrument includes a signal generator which generates an ac excitation signal for application to a load, including the device and the transmission line, a monitoring circuit which provides a digitally encoded signal representing the voltage across the load, and a microprocessor which operates under program control to provide an auto-ranging function by which range resistance is connected in circuit with the load to limit the load voltage to an acceptable range for the instrument, and an auto-compensating function by which compensating capacitance is connected in shunt with the range resistance to compensate for the effects of line capacitance.

  10. Automated ac galvanomagnetic measurement system

    NASA Technical Reports Server (NTRS)

    Szofran, F. R.; Espy, P. N.

    1985-01-01

    An automated, ac galvanomagnetic measurement system is described. Hall or van der Pauw measurements in the temperature range 10-300 K can be made at a preselected magnetic field without operator attendance. Procedures to validate sample installation and correct operation of other system functions, such as magnetic field and thermometry, are included. Advantages of ac measurements are discussed.

  11. AC loss measurements of twisted and untwisted BSCCO multifilamentary tapes

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenan; Amemiya, Naoyuki; Nishioka, Takamasa; Oh, Sang-Soo

    2005-01-01

    AC losses in twisted and untwisted BSCCO multifilamentary superconducting tapes with Ag matrix developed in DAPAS program were measured by an electrical method. Magnetization and transport losses were measured by a pick-up coil and by a voltage taps. Total AC loss during simultaneous application of AC transport current and an AC transverse magnetic field was given by the sum of the magnetization and transport losses measured during this simultaneous application. The magnetization loss without transport current of untwisted and twisted tapes was measured first to evaluate the effect of twisting to decouple filaments. Then, the total AC loss of the twisted tape was measured in transverse magnetic fields with various amplitudes and orientations, while the amplitude of the transport current was fixed. The measured total AC loss in a parallel transverse magnetic field was compared with some theoretical models to study the detailed characteristics of the measured total AC loss of the sample.

  12. Electrical characterization of Cu(In,Ga)Se2 thin films peeled off from Mo-coated soda-lime glass substrate by AC Hall measurement

    NASA Astrophysics Data System (ADS)

    Umehara, Takeshi; Iinuma, Shohei; Sadono, Adiyudha; Kurokawa, Yasuyoshi; Yamada, Akira

    2015-01-01

    We have developed a new evaluation method for electrical properties of Cu(In,Ga)Se2 (CIGS) grown on a Mo-coated soda-lime glass (SLG). The method consists of the peel-off process and the AC Hall measurement, which enables us to evaluate CIGS films grown on the Mo electrode. It was found, from the measurement, that the hole concentration of CIGS grown on a Mo-coated SLG was approximately two orders of magnitude higher than that on a SLG, suggesting the Na-doping effect. Furthermore, the hole mobility of 0.47 cm2/(V·s) was simultaneously measured, even though the film was deposited on the Mo electrode.

  13. Obtaining DC and AC isothermal electrical characteristics for RF MOSFET

    NASA Astrophysics Data System (ADS)

    Sahoo, A. K.; Fregonese, S.; Scheer, P.; Celi, D.; Juge, A.; Zimmer, T.

    2015-04-01

    In this paper we demonstrate a new and simple approach to obtain isothermal electrical characteristics of metal oxide field effect transistor (MOSFET) from conventional non-isothermal measurements. DC and continuous wave (CW) S-parameter measurements are performed at different chuck temperatures (Tchuck). Knowing the thermal resistance (RTH) of the device the variation of DC and AC characteristic due to self-heating can be de-embedded and all the isothermal DC data and AC data above isothermal frequency can be determined. The method is validated by comparing the results with pulsed DC and pulsed RF measurements and found to be in good agreements.

  14. Channel model for AC electric arc

    NASA Astrophysics Data System (ADS)

    Larsen, H. L.

    1993-06-01

    This report contains the results from calculations of free-burning AC electric arcs in argon. In order to calculate the arc current and arc voltage, the external electric circuit must be taken into consideration. The external circuit is modeled by an equivalent circuit consisting of an ideal AC voltage source, a loss resistance, and an inductance. The qualitative behavior of the current-voltage characteristic is in agreement with observed characteristics, but experimental data are necessary in order to check whether the calculated power loss is reasonable. Non-symmetry was modeled by introducing different anode and cathode falls in the two half periods. An attempt at taking into account different cathode current densities in the two half periods, depending on whether the electrode or silicon melt is cathode, did not give satisfactory results. Thermionic emission was assumed in both half periods, but this may not be the right mechanism when the silicon melt is cathode. The time delay of the AC arc compared to the DC case is modeled by a time constant. It was shown that this preset time constant must be in agreement with the mean 'mechanical' relaxation time in the arc in order to fulfill the energy balance. By updating the time constant until this is achieved, the time constant is eliminated as a parameter that must be chosen a priori.

  15. Advanced ac powertrain for electric vehicles

    SciTech Connect

    Slicker, J.M.; Kalns, L.

    1985-01-01

    The design of an ac propulsion system for an electric vehicle includes a three-phase induction motor, transistorized PWM inverter/battery charger, microprocessor-based controller, and two-speed automatic transaxle. This system was built and installed in a Mercury Lynx test bed vehicle as part of a Department of Energy propulsion system development program. An integral part of the inverter is a 4-kw battery charger which utilizes one of the bridge transistors. The overall inverter strategy for this configuration is discussed. The function of the microprocessor-based controller is described. Typical test results of the total vehicle and each of its major components are given, including system efficiencies and test track performance results.

  16. Space charge and charge trapping characteristics of cross-linked polyethylene subjected to ac electric stresses

    NASA Astrophysics Data System (ADS)

    Chong, Y. L.; Chen, G.; Miyake, H.; Matsui, K.; Tanaka, Y.; Takada, T.

    2006-04-01

    This paper reports on the result of space charge evolution in cross-linked polyethylene (XLPE) planar samples approximately 220 µm thick. The space charge measurement technique used in this study is the pulsed electroacoustic method. There are two phases to this experiment. In the first phase, the samples were subjected to dc 30 kVdc mm-1 and ac (sinusoidal) electric stress levels of 30 kVpk mm-1 at frequencies of 1, 10 and 50 Hz ac. In addition, ac space charge under 30 kVrms mm-1 and 60 kVpk mm-1 electric stress at 50 Hz was also investigated. The volts-off results showed that the amount of charge trapped in XLPE sample under dc electric stress is significantly bigger than samples under ac stress even when the applied ac stresses are substantially higher. The second phase of the experiment involves studying the dc space charge evolution in samples that were tested under ac stress during the first phase of the experiment. Ac ageing causes positive charge to become more dominant over negative charge. It was also discovered that ac ageing creates deeper traps, particularly for negative charge. This paper also gives a brief overview of the data processing methods used to analyse space charge under ac electric stress.

  17. Theoretical analysis on ac susceptibility measurements of superconductor tapes

    NASA Astrophysics Data System (ADS)

    Chen, Du-Xing; Sun, Yue-Ming; Li, Shuo; Fang, Jin

    2017-02-01

    Perpendicular ac susceptibility χ ={χ\\prime}-j{χ\\prime \\prime} of a superconducting long tape defined by magnetic moment and determined inductively by magnetic flux is calculated using Brandt’s technique from a power-law dependence of electric field on sheet current density. The requirements of χ measurements to the experimental setup and procedure are discussed based on the calculation results.

  18. AC-electric field dependent electroformation of giant lipid vesicles.

    PubMed

    Politano, Timothy J; Froude, Victoria E; Jing, Benxin; Zhu, Yingxi

    2010-08-01

    Giant vesicles of larger than 5 microm, which have been of intense interest for their potential as drug delivery vehicles and as a model system for cell membranes, can be rapidly formed from a spin-coated lipid thin film under an electric field. In this work, we explore the AC-field dependent electroformation of giant lipid vesicles in aqueous media over a wide range of AC-frequency from 1 Hz to 1 MHz and peak-to-peak field strength from 0.212 V/mm to 40 V/mm between two parallel conducting electrode surfaces. By using fluorescence microscopy, we perform in-situ microscopic observations of the structural evolution of giant vesicles formed from spin-coated lipid films under varied uniform AC-electric fields. The real-time observation of bilayer bulging from the lipid film, vesicle growth and fusing further examine the critical role of AC-induced electroosmotic flow of surrounding fluids for giant vesicle formation. A rich AC-frequency and field strength phase diagram is obtained experimentally to predict the AC-electroformation of giant unilamellar vesicles (GUVs) of l-alpha-phosphatidylcholine, where a weak dependence of vesicle size on AC-frequency is observed at low AC-field voltages, showing decreased vesicle size with a narrowed size distribution with increased AC-frequency. Formation of vesicles was shown to be constrained by an upper field strength of 10 V/mm and an upper AC-frequency of 10 kHz. Within these parameters, giant lipid vesicles were formed predominantly unilamellar and prevalent across the entire electrode surfaces.

  19. Trapping of Rb Atoms by ac Electric Fields

    SciTech Connect

    Schlunk, Sophie; Marian, Adela; Geng, Peter; Meijer, Gerard; Schoellkopf, Wieland; Mosk, Allard P.

    2007-06-01

    We demonstrate trapping of an ultracold gas of neutral atoms in a macroscopic ac electric trap. Three-dimensional confinement is obtained by switching between two saddle-point configurations of the electric field. Stable trapping is observed in a narrow range of switching frequencies around 60 Hz. The dynamic confinement of the atoms is directly visualized at different phases of the ac switching cycle. We observe about 10{sup 5} Rb atoms in the 1 mm{sup 3} large and several microkelvins deep trap with a lifetime of approximately 5 s.

  20. Cascading failures in ac electricity grids.

    PubMed

    Rohden, Martin; Jung, Daniel; Tamrakar, Samyak; Kettemann, Stefan

    2016-09-01

    Sudden failure of a single transmission element in a power grid can induce a domino effect of cascading failures, which can lead to the isolation of a large number of consumers or even to the failure of the entire grid. Here we present results of the simulation of cascading failures in power grids, using an alternating current (AC) model. We first apply this model to a regular square grid topology. For a random placement of consumers and generators on the grid, the probability to find more than a certain number of unsupplied consumers decays as a power law and obeys a scaling law with respect to system size. Varying the transmitted power threshold above which a transmission line fails does not seem to change the power-law exponent q≈1.6. Furthermore, we study the influence of the placement of generators and consumers on the number of affected consumers and demonstrate that large clusters of generators and consumers are especially vulnerable to cascading failures. As a real-world topology, we consider the German high-voltage transmission grid. Applying the dynamic AC model and considering a random placement of consumers, we find that the probability to disconnect more than a certain number of consumers depends strongly on the threshold. For large thresholds the decay is clearly exponential, while for small ones the decay is slow, indicating a power-law decay.

  1. Cascading failures in ac electricity grids

    NASA Astrophysics Data System (ADS)

    Rohden, Martin; Jung, Daniel; Tamrakar, Samyak; Kettemann, Stefan

    2016-09-01

    Sudden failure of a single transmission element in a power grid can induce a domino effect of cascading failures, which can lead to the isolation of a large number of consumers or even to the failure of the entire grid. Here we present results of the simulation of cascading failures in power grids, using an alternating current (AC) model. We first apply this model to a regular square grid topology. For a random placement of consumers and generators on the grid, the probability to find more than a certain number of unsupplied consumers decays as a power law and obeys a scaling law with respect to system size. Varying the transmitted power threshold above which a transmission line fails does not seem to change the power-law exponent q ≈1.6 . Furthermore, we study the influence of the placement of generators and consumers on the number of affected consumers and demonstrate that large clusters of generators and consumers are especially vulnerable to cascading failures. As a real-world topology, we consider the German high-voltage transmission grid. Applying the dynamic AC model and considering a random placement of consumers, we find that the probability to disconnect more than a certain number of consumers depends strongly on the threshold. For large thresholds the decay is clearly exponential, while for small ones the decay is slow, indicating a power-law decay.

  2. Assessment of US electric vehicle programs with ac powertrains

    SciTech Connect

    Kevala, R.J. . Transportation Consulting Div.)

    1990-02-01

    AC powertrain technology is a promising approach to improving the performance of electric vehicles. Four major programs are now under way in the United States to develop ac powertrains: the Ford/General Electric single-shaft electric propulsion system (ETX-II), the Eaton dual-shaft electric propulsion system (DSEP), the Jet Propulsion Laboratories (JPL) integrated ac motor drive and recharge system, and the Massachusetts Institute of Technology (MIT) variable reluctance motor (VRM) drive. The JPL program is sponsored by EPRI; the other three programs are funded by the US Department of Energy. This preliminary assessment of the four powertrain programs focuses on potential performance, costs, safety, and commercial feasibility. Interviews with program personnel were supplemented by computer simulations of electric vehicle performance using the four systems. Each of the four powertrains appears superior to standard dc powertrain technology in terms of performance and weight. The powertrain technologies studied in this assessment are at varying degrees of technological maturity. One or more of the systems may be ready for incorporation into an advanced electric vehicle during the early 1990s. Each individual report will have a separate abstract. 5 refs., 37 figs., 29 tabs.

  3. Performance testing of the AC propulsion ELX electric vehicle

    SciTech Connect

    Kramer, W.E.; MacDowall, R.D.; Burke, A.F.

    1994-06-01

    Performance testing of the AC Propulsion ELX electric vehicle is described. Test data are presented and analyzed. The ELX vehicle is the first of a series of electric vehicles of interest to the California Air Resources Board. The test series is being conducted under a Cooperative Research and Development Agreement (CRADA) between the US Department of energy and the California Air Resources Board. The tests which were conducted showed that the AC Propulsion ELX electric vehicle has exceptional acceleration and range performance. when the vehicle`s battery was fully charged, the vehicle can accelerate from 0 to 96 km/h in about 10 seconds. Energy consumption and range tests using consecutive FUDS and HWFET Driving cycles (the all-electric cycle) indicate that the energy economy of the AC Propulsion ELX electric vehicle with regenerative braking is 97 W{center_dot}h/km, with a range of 153 km (95 miles). Computer simulations performed using the SIMPLEV Program indicate that the vehicle would have a range of 327 km (203 miles) on the all-electric cycle if the lead acid batteries were replaced with NiMH batteries having an energy density of 67 W{center_dot}h/kg. Comparisons of FUDS test data with and without regenerative braking indicated that regenerative braking reduced the energy consumption of the ELX vehicle by approximately 25%.

  4. Test plan for performance testing of the Eaton AC-3 electric vehicle

    SciTech Connect

    Crumley, R.L.; Heiselmann, H.W.

    1985-04-01

    An alternating current (ac) propulsion system for an electric vehicle has been developed and tested by the Eaton Corporation. The test bed vehicle is a modified 1981 Mercury Lynx. The test plan has been prepared specifically for the third modification to this test bed and identified as the Eaton AC-3. The scope of the EG and G testing at INEL to be done on the Eaton AC-3 will include coastdown and dynamometer tests but will not include environmental, on-road, or track testing. Coastdown testing will be performed in accordance with SAE J-1263 (SAE Recommended Practice for Road Load Measurement and Dynamometer Simulation Using Coastdown Techniques).

  5. 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

  6. The ac propulsion system for an electric vehicle, phase 1

    NASA Technical Reports Server (NTRS)

    Geppert, S.

    1981-01-01

    A functional prototype of an electric vehicle ac propulsion system was built consisting of a 18.65 kW rated ac induction traction motor, pulse width modulated (PWM) transistorized inverter, two speed mechanically shifted automatic transmission, and an overall drive/vehicle controller. Design developmental steps, and test results of individual components and the complex system on an instrumented test frame are described. Computer models were developed for the inverter, motor and a representative vehicle. A preliminary reliability model and failure modes effects analysis are given.

  7. Fast electric dipole transitions in Ra-Ac nuclei

    SciTech Connect

    Ahmad, I.

    1985-01-01

    Lifetime of levels in /sup 225/Ra, /sup 225/Ac, and /sup 227/Ac have been measured by delayed coincidence techniques and these have been used to determine the E1 gamma-ray transition probabilities. The reduced E1 transition probabilities. The reduced E1 transition probabilities in /sup 225/Ra and /sup 225/Ac are about two orders of magnitude larger than the values in mid-actinide nuclei. On the other hand, the E1 rate in /sup 227/Ac is similar to those measured in heavier actinides. Previous studies suggest the presence of octupole deformation in all the three nuclei. The present investigation indicates that fast E1 transitions occur for nuclei with octupole deformation. However, the studies also show that there is no one-to-one correspondence between E1 rate and octupole deformation. 13 refs., 4 figs.

  8. AC propulsion system for an electric vehicle, phase 2

    NASA Technical Reports Server (NTRS)

    Slicker, J. M.

    1983-01-01

    A second-generation prototype ac propulsion system for a passenger electric vehicle was designed, fabricated, tested, installed in a modified Mercury Lynx vehicle and track tested at the Contractor's site. The system consisted of a Phase 2, 18.7 kw rated ac induction traction motor, a 192-volt, battery powered, pulse-width-modulated, transistorized inverter packaged for under rear seat installation, a 2-axis, 2-speed, automatically-shifted mechanical transaxle and a microprocessor-based powertrain/vehicle controller. A diagnostics computer to assist tuning and fault finding was fabricated. Dc-to-mechanical-system efficiency varied from 78% to 82% as axle speed/torque ranged from 159 rpm/788 nm to 65 rpm/328 nm. Track test efficiency results suggest that the ac system will be equal or superior to dc systems when driving urban cycles. Additional short-term work is being performed under a third contract phase (AC-3) to raise transaxle efficiency to predicted levels, and to improve starting and shifting characteristics. However, the long-term challenge to the system's viability remains inverter cost. A final report on the Phase 2 system, describing Phase 3 modifications, will be issued at the conclusion of AC-3.

  9. Measured losses in superconductor magnets for 60-Hertz ac operation.

    NASA Technical Reports Server (NTRS)

    Hamlet, I. L.; Kilgore, R. A.

    1971-01-01

    Results of an experimental study of electrical losses in superconductor magnets. Preliminary 60-Hz ac loss data are presented for coils constructed of Nb3Sn ribbon, Nb-Ti cable, and multifilament Nb-Ti. Losses have been measured for different size coils up to approximately 20 cm in diameter. Of the conductor types tested, Nb3Sn ribbon has the lowest losses for ac operation. In Nb3Sn-ribbon coils of different sizes, the loss per unit length of conductor is shown to decrease with a decrease in the rate of change of current and to increase, in general, with increase in coil size. An important aspect of the study is the high degree of repeatability of the data.

  10. Simulational studies of epitaxial semiconductor superlattices: Quantum dynamical phenomena in ac and dc electric fields

    SciTech Connect

    Reynolds, Joseph

    1997-10-08

    Using high-accuracy numerical methods the author investigates the dynamics of independent electrons in both ideal and realistic superlattices subject to arbitrary ac and/or dc electric fields. For a variety of superlattice potentials, optically excited initial wave packets, and combinations of ac and dc electric fields, he numerically solves the time-dependent Schroedinger equation. In the case of ideal periodic superlattice potentials, he investigates a long list of dynamical phenomena involving multiple miniband transitions and time-dependent electric fields. These include acceleration effects associated with interminiband transitions in strong fields, Zener resonances between minibands, dynamic localization with ac fields, increased single-miniband transport with an auxiliary resonant ac field, and enhanced or suppressed interminiband probability exchange using an auxiliary ac field. For all of the cases studied, the resulting time-dependent wave function is analyzed by projecting the data onto convenient orthonormal bases. This allows a detailed comparison with approximately analytic treatments. In an effort to explain the rapid decay of experimentally measured Bloch oscillation (BO) signals the author incorporates a one-dimensional representation of interface roughness (IR) into their superlattice potential. He shows that as a result of IR, the electron dynamics can be characterized in terms of many discrete, incommensurate frequencies near the Block frequency. Chapters 2, 3, 4 and 5 have been removed from this report and will be processed separately.

  11. AC electrical properties of FeIn2S4

    NASA Astrophysics Data System (ADS)

    Niftiev, N. N.; Tagiev, O. B.; Muradov, M. B.; Mamedov, F. M.

    2012-04-01

    The frequency and temperature dependences of the ac capacitance and resistivity of FeIn2S4 semiconductors are studied. Resonances are observed at certain temperatures in the frequency range (2.5-5.0) × 105 Hz. The permittivity of the crystals and the activation energy of charge carriers are determined. It is found that electrical conduction in the given temperature interval is governed by an activation mechanism. The activation energy is frequency-dependent, because the relaxation time of barrier layers decreases with rising frequency.

  12. A PWM transistor inverter for an ac electric vehicle drive

    NASA Technical Reports Server (NTRS)

    Slicker, J. M.

    1981-01-01

    A prototype system consisting of closely integrated motor, inverter, and transaxle has been built in order to demonstrate the feasibility of a three-phase ac transistorized inverter for electric vehicle applications. The microprocessor-controlled inverter employs monolithic power transistors to drive an oil-cooled, three-phase induction traction motor at a peak output power of 30 kW from a 144 V battery pack. Transistor safe switching requirements are discussed, and a circuit is presented for recovering trapped snubber inductor energy at transistor turn-off.

  13. Electrical Model of Balanced AC HTS Power Cable

    NASA Astrophysics Data System (ADS)

    Zuijderduin, R.; Chevtchenko, O.; Smit, J. J.; Willén, D.; Melnik, I.; Geschiere, A.

    The future electricity grid will be more sustainable and it will have more power transmission and distribution capability with more electrical power added from decentralized sources on distribution level and from wind parks and other large sources on transmission level. More interconnections and more underground transmission and distribution will be put up. Use of high temperature superconducting (HTS) power cables provides solutions to many of the future grid problems caused by these trends. In this paper we present an electrical model of a balanced 6 km-long three phase triaxial HTS power cable for the Dutch project being developed by a consortium of Alliander, Ultera™ and TUD. The cable currents in all three phases are balanced by selecting proper twist pitches and insulation thickness. The paper focuses on determining inductances, capacitances and AC losses of the balanced cable. Using the developed model, we also determine the voltage drop as function of the cable length, the neutral current and the effect of the imbalanced capacitances on the current distribution of the Dutch distribution cable. The model is validated and it can be used for accurate simulation of the electrical behaviour of triaxial HTS cables in electrical grids.

  14. Long-range response in ac electricity grids.

    PubMed

    Jung, Daniel; Kettemann, Stefan

    2016-07-01

    Local changes in the topology of electricity grids can cause overloads far away from the disturbance [D. Witthaut and M. Timme, Eur. Phys. J. B 86, 377 (2013)EPJBFY1434-602810.1140/epjb/e2013-40469-4], making the prediction of the robustness against changes in the topology-for example, caused by power outages or grid extensions-a challenging task. The impact of single-line additions on the long-range response of dc electricity grids has recently been studied [D. Labavić, R. Suciu, H. Meyer-Ortmanns, and S. Kettemann, Eur. Phys. J.: Spec. Top. 223, 2517 (2014)1951-635510.1140/epjst/e2014-02273-0]. By solving the real part of the static ac load flow equations, we conduct a similar investigation for ac grids. In a regular two-dimensional grid graph with cyclic boundary conditions, we find a power law decay for the change of power flow as a function of distance to the disturbance over a wide range of distances. The power exponent increases and saturates for large system sizes. By applying the same analysis to the German transmission grid topology, we show that also in real-world topologies a long-ranged response can be found.

  15. Long-range response in ac electricity grids

    NASA Astrophysics Data System (ADS)

    Jung, Daniel; Kettemann, Stefan

    2016-07-01

    Local changes in the topology of electricity grids can cause overloads far away from the disturbance [D. Witthaut and M. Timme, Eur. Phys. J. B 86, 377 (2013), 10.1140/epjb/e2013-40469-4], making the prediction of the robustness against changes in the topology—for example, caused by power outages or grid extensions—a challenging task. The impact of single-line additions on the long-range response of dc electricity grids has recently been studied [D. Labavić, R. Suciu, H. Meyer-Ortmanns, and S. Kettemann, Eur. Phys. J.: Spec. Top. 223, 2517 (2014), 10.1140/epjst/e2014-02273-0]. By solving the real part of the static ac load flow equations, we conduct a similar investigation for ac grids. In a regular two-dimensional grid graph with cyclic boundary conditions, we find a power law decay for the change of power flow as a function of distance to the disturbance over a wide range of distances. The power exponent increases and saturates for large system sizes. By applying the same analysis to the German transmission grid topology, we show that also in real-world topologies a long-ranged response can be found.

  16. Electric-Field Instrument With Ac-Biased Corona Point

    NASA Technical Reports Server (NTRS)

    Markson, R.; Anderson, B.; Govaert, J.

    1993-01-01

    Measurements indicative of incipient lightning yield additional information. New instrument gives reliable readings. High-voltage ac bias applied to needle point through high-resistance capacitance network provides corona discharge at all times, enabling more-slowly-varying component of electrostatic potential of needle to come to equilibrium with surrounding air. High resistance of high-voltage coupling makes instrument insensitive to wind. Improved corona-point instrument expected to yield additional information assisting in safety-oriented forecasting of lighting.

  17. Particle Agglomeration in Bipolar Barb Agglomerator Under AC Electric Field

    NASA Astrophysics Data System (ADS)

    Huang, Chao; Ma, Xiuqin; Sun, Youshan; Wang, Meiyan; Zhang, Changping; Lou, Yueya

    2015-04-01

    The development of an efficient technology for removing fine particles in flue gas is essential as the haze is becoming more and more serious. To improve agglomeration effectiveness of fine particles, a dual zone electric agglomeration device consisting of a charging chamber and an agglomeration chamber with bipolar barb electrodes was developed. The bipolar barb electric agglomerator with a polar distance of 200 mm demonstrates good agglomeration effectiveness for particles with a size less than 8.0 μm under applied AC electric field. An optimal condition for achieving better agglomeration effectiveness was found to be as follows: flue gas flow velocity of 3.00 m/s, particle concentration of 2.00 g/m3, output voltage of 35 kV and length of the barb of 16 mm. In addition, 4.0-6.0 μm particles have the best effectiveness with the variation of particle volume occupancy of -3.2. supported by the Key Technology R&D Program of Hebei, China (No. 13211207D)

  18. AC Electric Field Activated Shape Memory Polymer Composite

    NASA Technical Reports Server (NTRS)

    Kang, Jin Ho; Siochi, Emilie J.; Penner, Ronald K.; Turner, Travis L.

    2011-01-01

    Shape memory materials have drawn interest for applications like intelligent medical devices, deployable space structures and morphing structures. Compared to other shape memory materials like shape memory alloys (SMAs) or shape memory ceramics (SMCs), shape memory polymers (SMPs) have high elastic deformation that is amenable to tailored of mechanical properties, have lower density, and are easily processed. However, SMPs have low recovery stress and long response times. A new shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive fillers to enhance its thermo-mechanical characteristics. A new composition of shape memory thermosetting polymer nanocomposite (LaRC-SMPC) was synthesized with conductive functionalized graphene sheets (FGS) to enhance its thermo-mechanical characteristics. The elastic modulus of LaRC-SMPC is approximately 2.7 GPa at room temperature and 4.3 MPa above its glass transition temperature. Conductive FGSs-doped LaRC-SMPC exhibited higher conductivity compared to pristine LaRC SMP. Applying an electric field at between 0.1 Hz and 1 kHz induced faster heating to activate the LaRC-SMPC s shape memory effect relative to applying DC electric field or AC electric field at frequencies exceeding1 kHz.

  19. Delocalization of disturbances and the stability of ac electricity grids.

    PubMed

    Kettemann, Stefan

    2016-12-01

    In order to study how local disturbances affect the ac grid stability, we start from nonlinear power balance equations and map them to complex linear wave equations. Having obtained stationary solutions with phases φ_{i} at generator and consumer nodes i, we next study the dynamics of deviations. Starting with an initially localized perturbation, it is found to spread in a periodic grid diffusively throughout the grid. We find the parametric dependence of diffusion constant D. We apply the same solution strategy to general grid topologies and analyze their stability against local perturbations. The perturbation remains either localized or becomes delocalized, depending on grid topology, power capacity, and distribution of consumers and generator power P_{i}. Delocalization is found to increase the lifetime of perturbations and thereby their influence on grid stability, whereas localization results in an exponentially fast decay of perturbations at all grid sites. These results may therefore lead to new strategies to control the stability of electricity grids.

  20. Delocalization of disturbances and the stability of ac electricity grids

    NASA Astrophysics Data System (ADS)

    Kettemann, Stefan

    2016-12-01

    In order to study how local disturbances affect the ac grid stability, we start from nonlinear power balance equations and map them to complex linear wave equations. Having obtained stationary solutions with phases φi at generator and consumer nodes i , we next study the dynamics of deviations. Starting with an initially localized perturbation, it is found to spread in a periodic grid diffusively throughout the grid. We find the parametric dependence of diffusion constant D . We apply the same solution strategy to general grid topologies and analyze their stability against local perturbations. The perturbation remains either localized or becomes delocalized, depending on grid topology, power capacity, and distribution of consumers and generator power Pi. Delocalization is found to increase the lifetime of perturbations and thereby their influence on grid stability, whereas localization results in an exponentially fast decay of perturbations at all grid sites. These results may therefore lead to new strategies to control the stability of electricity grids.

  1. Dielectric behavior and ac electrical conductivity in samarium substituted Mg-Ni ferrites

    NASA Astrophysics Data System (ADS)

    Melagiriyappa, E.; Veena, M.; Somashekarappa, A.; Shankaramurthy, G. J.; Jayanna, H. S.

    2014-08-01

    Samarium substituted MgNi ferrites with composition Mg1-xNixFe2-ySmyO4 ( x = 0, 0.2, 0.4, 0.6, 0.8, 1.0; y = 0.0, 0.05, 0.1) have been prepared by ceramic method. Dielectric measurements of the samples have been carried out at room temperature as a function of frequency and composition. X-ray diffraction patterns have confirmed the single-phase spinel cubic structure for all the samples. Dielectric constant ( ɛ') and dielectric loss (tan δ) decrease while ac electrical conductivity ( σ ac ) increases with increase in frequency. Dielectric properties have been explained on the basis of Maxwell-Wagner's two layer model. The conduction mechanism in these ferrites is due to electron hopping between Ni2+ and Ni3+ as well as Fe3+ and Fe2+ ions on octahedral sites. Dielectric constant and ac conductivity increases and decreases respectively with nickel content. A significant reduction in the values of dielectric constant and ac electrical conductivity has been observed in Sm3+ ions substituted samples.

  2. Comprehensive analysis of human cells motion under an irrotational AC electric field in an electro-microfluidic chip.

    PubMed

    Vaillier, Clarisse; Honegger, Thibault; Kermarrec, Frédérique; Gidrol, Xavier; Peyrade, David

    2014-01-01

    AC electrokinetics is a versatile tool for contact-less manipulation or characterization of cells and has been widely used for separation based on genotype translation to electrical phenotypes. Cells responses to an AC electric field result in a complex combination of electrokinetic phenomena, mainly dielectrophoresis and electrohydrodynamic forces. Human cells behaviors to AC electrokinetics remain unclear over a large frequency spectrum as illustrated by the self-rotation effect observed recently. We here report and analyze human cells behaviors in different conditions of medium conductivity, electric field frequency and magnitude. We also observe the self-rotation of human cells, in the absence of a rotational electric field. Based on an analytical competitive model of electrokinetic forces, we propose an explanation of the cell self-rotation. These experimental results, coupled with our model, lead to the exploitation of the cell behaviors to measure the intrinsic dielectric properties of JURKAT, HEK and PC3 human cell lines.

  3. Comprehensive Analysis of Human Cells Motion under an Irrotational AC Electric Field in an Electro-Microfluidic Chip

    PubMed Central

    Kermarrec, Frédérique; Gidrol, Xavier; Peyrade, David

    2014-01-01

    AC electrokinetics is a versatile tool for contact-less manipulation or characterization of cells and has been widely used for separation based on genotype translation to electrical phenotypes. Cells responses to an AC electric field result in a complex combination of electrokinetic phenomena, mainly dielectrophoresis and electrohydrodynamic forces. Human cells behaviors to AC electrokinetics remain unclear over a large frequency spectrum as illustrated by the self-rotation effect observed recently. We here report and analyze human cells behaviors in different conditions of medium conductivity, electric field frequency and magnitude. We also observe the self-rotation of human cells, in the absence of a rotational electric field. Based on an analytical competitive model of electrokinetic forces, we propose an explanation of the cell self-rotation. These experimental results, coupled with our model, lead to the exploitation of the cell behaviors to measure the intrinsic dielectric properties of JURKAT, HEK and PC3 human cell lines. PMID:24736275

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

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.

    1991-01-01

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

  5. The ac and dc electric field meters developed for the US Department of Energy

    NASA Technical Reports Server (NTRS)

    Kirkham, H.; Johnston, A.; Jackson, S.; Sheu, K.

    1987-01-01

    Two space-potential electric field meters developed at the Jet Propulsion Laboratory under the auspices of the U.S. Department of Energy are described. One of the meters was designed to measure dc fields, the other ac fields. Both meters use fiber optics to couple a small measuring probe to a remote readout device, so as to minimize field perturbation due to the presence of the probe. By using coherent detection, it has been possible to produce instruments whose operating range extends from about 10 V/m up to about 2.5 kV/cm, without the need for range switching on the probe. The electrical and mechanical design of both meters are described in detail. Data from laboratory tests are presented, as well as the results of the tests at the National Bureau of Standards and the Electric Power Research Institute's High Voltage Transmission Research Facility.

  6. Concentrating membrane proteins using asymmetric traps and AC electric fields.

    PubMed

    Cheetham, Matthew R; Bramble, Jonathan P; McMillan, Duncan G G; Krzeminski, Lukasz; Han, Xiaojun; Johnson, Benjamin R G; Bushby, Richard J; Olmsted, Peter D; Jeuken, Lars J C; Marritt, Sophie J; Butt, Julea N; Evans, Stephen D

    2011-05-04

    Membrane proteins are key components of the plasma membrane and are responsible for control of chemical ionic gradients, metabolite and nutrient transfer, and signal transduction between the interior of cells and the external environment. Of the genes in the human genome, 30% code for membrane proteins (Krogh et al. J. Mol. Biol.2001, 305, 567). Furthermore, many FDA-approved drugs target such proteins (Overington et al. Nat. Rev. Drug Discovery 2006, 5, 993). However, the structure-function relationships of these are notably sparse because of difficulties in their purification and handling outside of their membranous environment. Methods that permit the manipulation of membrane components while they are still in the membrane would find widespread application in separation, purification, and eventual structure-function determination of these species (Poo et al. Nature 1977, 265, 602). Here we show that asymmetrically patterned supported lipid bilayers in combination with AC electric fields can lead to efficient manipulation of charged components. We demonstrate the concentration and trapping of such components through the use of a "nested trap" and show that this method is capable of yielding an approximately 30-fold increase in the average protein concentration. Upon removal of the field, the material remains trapped for several hours as a result of topographically restricted diffusion. Our results indicate that this method can be used for concentrating and trapping charged membrane components while they are still within their membranous environment. We anticipate that our approach could find widespread application in the manipulation and study of membrane proteins.

  7. Study of AC electrical conduction mechanisms in an epoxy polymer

    NASA Astrophysics Data System (ADS)

    Jilani, Wissal; Mzabi, Nissaf; Gallot-Lavallée, Olivier; Fourati, Najla; Zerrouki, Chouki; Zerrouki, Rachida; Guermazi, Hajer

    2015-11-01

    The AC conductivity of an epoxy resin was investigated in the frequency range 10^{-1} - 106 Hz at temperatures ranging from -100 to 120 °C. The frequency dependence of σ_{ac} was described by the law: σ_{ac}=ω \\varepsilon0\\varepsilon^''_{HN}+Aωs. The study of temperature variation of the exponent (s) reveals two conduction models: the AC conduction dependence upon temperature is governed by the small polaron tunneling mechanism (SPTM) at low temperature (-100 -60 °C) and the correlated barrier hopping (CHB) model at high temperature (80-120 °C).

  8. Droplet condensation on superhydrophobic surfaces with enhanced dewetting under a tangential AC electric field

    NASA Astrophysics Data System (ADS)

    Yan, Xinzhu; Li, Jian; Li, Licheng; Huang, Zhengyong; Wang, Feipeng; Wei, Yuan

    2016-10-01

    In this Letter, the dewetting behavior of superhydrophobic condensing surfaces under a tangential AC electric field is reported. The surface coverage of condensed droplets only exhibits a negligible increase with time. The jumping frequency of droplets is enhanced. The AC electric field motivates the dynamic transition of droplets from stretch to recoil, resulting in the counterforce propelling droplet jumping. The considerable horizontal component of jumping velocity facilitates droplet departure from superhydrophobic surfaces. Both the amplitude and frequency of AC voltage are important factors for droplet departure and dewetting effect. Thereby, the tangential electric field provides a unique and easily implementable approach to enhance droplet removal from superhydrophobic condensing surfaces.

  9. The movement of actin-myosin biomolecular linear motor under AC electric fields: an experimental study.

    PubMed

    Lee, Yongkuk; Famouri, Parviz

    2013-03-15

    The role of actin-myosin as a biomolecular linear motor is considered a transport system at nanoscale because of their size, efficiency and functionality. To utilize the ability to transport, it is essential to control the random movement of actin filaments (F-actin) on myosin coated substrate. In the presence of an alternating current (AC) electric field, the direction of F-actin movement is regulated by electro-orientation torque and, as a result, its movement is perpendicularly toward the electrode edges. Our data confirm such aligned movement is proportional to the strength of applied electric field. Interestingly, the aligned movement is found frequency-dependent and the electrothermal effect is observed by means of the velocity measurement of aligned F-actin movement. The findings in this study may provide constructive information for manipulating actin-myosin nanotransport system to build functional nanodevices in future work.

  10. Instantaneous velocity measurement of AC electroosmotic flows by laser induced fluorescence photobleaching anemometer with high temporal resolution

    NASA Astrophysics Data System (ADS)

    Zhao, Wei; Yang, Fang; Qiao, Rui; Wang, Guiren; Rui Qiao Collaboration

    2015-11-01

    Understanding the instantaneous response of flows to applied AC electric fields may help understand some unsolved issues in induced-charge electrokinetics and enhance performance of microfluidic devices. Since currently available velocimeters have difficulty in measuring velocity fluctuations with frequency higher than 1 kHz, most experimental studies so far focus only on the average velocity measurement in AC electrokinetic flows. Here, we present measurements of AC electroosmotic flow (AC-EOF) response time in microchannels by a novel velocimeter with submicrometer spatial resolution and microsecond temporal resolution, i.e. laser-induced fluorescence photobleaching anemometer (LIFPA). Several parameters affecting the AC-EOF response time to the applied electric signal were investigated, i.e. channel length, transverse position and solution conductivity. The experimental results show that the EOF response time under a pulsed electric field decreases with the reduction of the microchannel length, distance between the detection position to the wall and the conductivity of the solution. This work could provide a new powerful tool to measure AC electrokinetics and enhance our understanding of AC electrokinetic flows.

  11. Electron Temperature Measurement by Floating Probe Method Using AC Voltage

    NASA Astrophysics Data System (ADS)

    Satoshi, Nodomi; Shuichi, Sato; Mikio, Ohuchi

    2016-11-01

    This study presents a novel floating probe method to measure electron temperatures using a hollow cathode-type discharge tube. The proposed method detects a shift in the floating potential when an AC voltage is applied to a probe through an intermediary blocking capacitor. The shift in the floating potential is described as a function of the electron temperature and the applied AC voltage. The floating probe method is simpler than the Langmuir probe method because it does not require the measurement of volt-ampere characteristics. As the input AC voltage increases, the electron temperature converges. The electron temperature measured using the floating probe method with an applied sinusoidal voltage shows a value close to the first (tail) electron temperature in the range of the floating potential.

  12. The AC (Alternating Current) Electrical Behavior of Multi-layered Thermoelectric Devices

    NASA Astrophysics Data System (ADS)

    Alim, Mohammad A.; Budak, Satilmis; Bhattacharjee, Sudip

    2016-11-01

    In this study the ac (alternating current) small-signal electrical data in the frequency range 5 Hz ≤ f ≤ 13 MHz are obtained for the multi-layered thermoelectric (TE) devices to extract underlying operative mechanisms via an equivalent circuit model. This model is developed from the complex plane plots in conjunction with the Bode plot. It is observed that the inductive behavior is prevalent for both unbombarded and bombarded TE devices regardless of the doses as both types are observed as somewhat weak in thermoelectric properties. The bombarded multi-layered devices followed a systematic pattern in ac behavior via semicircular relaxation both in the impedance and admittance planes for the same measured data. This pattern is attributed to the transition from one lumped behavior to two distinct mechanisms. It is observed that the conductive nature of the equivalent circuit model via non-blocking (non-capacitive) elements, attributed to the underlying operative electrical paths between the two opposite electrodes across the multi-layered device exists, satisfying direct current conditions of the equivalent circuit model. The inductive behavior at high frequencies originates from the conductive aspect of the lumped response of the device in addition to the contribution of the electrode leads. Thus, the proposed equivalent circuit model contains external inductance that verifies a meaningful representation of the multi-layered TE device, though weak in thermoelectric properties.

  13. Wind-powered asynchronous AC/DC/AC converter system. [for electric power supply regulation

    NASA Technical Reports Server (NTRS)

    Reitan, D. K.

    1973-01-01

    Two asynchronous ac/dc/ac systems are modelled that utilize wind power to drive a variable or constant hertz alternator. The first system employs a high power 60-hertz inverter tie to the large backup supply of the power company to either supplement them from wind energy, storage, or from a combination of both at a preset desired current; rectifier and inverter are identical and operate in either mode depending on the silicon control rectifier firing angle. The second system employs the same rectification but from a 60-hertz alternator arrangement; it provides mainly dc output, some sinusoidal 60-hertz from the wind bus and some high harmonic content 60-hertz from an 800-watt inverter.

  14. Measurement of the 225Ac half-life.

    PubMed

    Pommé, S; Marouli, M; Suliman, G; Dikmen, H; Van Ammel, R; Jobbágy, V; Dirican, A; Stroh, H; Paepen, J; Bruchertseifer, F; Apostolidis, C; Morgenstern, A

    2012-11-01

    The (225)Ac half-life was determined by measuring the activity of (225)Ac sources as a function of time, using various detection techniques: α-particle counting with a planar silicon detector at a defined small solid angle and in a nearly-2π geometry, 4πα+β counting with a windowless CsI sandwich spectrometer and with a pressurised proportional counter, gamma-ray spectrometry with a HPGe detector and with a NaI(Tl) well detector. Depending on the technique, the decay was followed for 59-141 d, which is about 6-14 times the (225)Ac half-life. The six measurement results were in good mutual agreement and their mean value is T(1/2)((225)Ac)=9.920 (3)d. This half-life value is more precise and better documented than the currently recommended value of 10.0 d, based on two old measurements lacking uncertainty evaluations.

  15. Storing the Electric Energy Produced by an AC Generator

    ERIC Educational Resources Information Center

    Carvalho, P. Simeao; Lima, Ana Paula; Carvalho, Pedro Simeao

    2010-01-01

    Producing energy from renewable energy sources is nowadays a priority in our society. In many cases this energy comes as electric energy, and when we think about electric energy generators, one major issue is how we can store that energy. In this paper we discuss how this can be done and give some ideas for applications that can serve as a…

  16. A study of some features of ac and dc electric power systems for a space station

    NASA Technical Reports Server (NTRS)

    Hanania, J. I.

    1983-01-01

    This study analyzes certain selected topics in rival dc and high frequency ac electric power systems for a Space Station. The interaction between the Space Station and the plasma environment is analyzed, leading to a limit on the voltage for the solar array and a potential problem with resonance coupling at high frequencies. Certain problems are pointed out in the concept of a rotary transformer, and further development work is indicated in connection with dc circuit switching, special design of a transmission conductor for the ac system, and electric motors. The question of electric shock hazards, particularly at high frequency, is also explored. and a problem with reduced skin resistance and therefore increased hazard with high frequency ac is pointed out. The study concludes with a comparison of the main advantages and disadvantages of the two rival systems, and it is suggested that the choice between the two should be made after further studies and development work are completed.

  17. The photon: EM fields, electrical potentials, and AC charge

    NASA Astrophysics Data System (ADS)

    Meulenberg, A.; Hudgins, W. R.; Penland, R. F.

    2015-09-01

    Photons are here considered to be resonant oscillations (solitons) in four dimensions (space/time) of an undefined `field' otherwise generally existing at a local energy minimum. The photons' constituent EM fields result in elevated energy, and therefore potentials, within that field. It is in the context of the standing waves of and between photons that the EM fields and potentials lead to a description of alternating (AC) `currents' (of some form) of unquantized alternating `charge' (of some sort). The main topic of this paper is the alternating charge.

  18. Dynamics of particle chain formation in a liquid polymer under ac electric field: modeling and experiments

    NASA Astrophysics Data System (ADS)

    Belijar, G.; Valdez-Nava, Z.; Diaham, S.; Laudebat, L.; Jones, T. B.; Lebey, T.

    2017-01-01

    Polymer/ceramic composite materials are of great interest for their many potential applications because of their ability to combine at least two properties of the constitutive elements: particles and matrix. In most cases, such enhanced properties are required only in one direction. Orthotropic materials can be elaborated by applying an ac electric field to form particle chain structures in the direction of the electric field due to the dielectrophoretic interactions affecting the particles. However, there is still a lack in the understanding of the impact of the structures on the properties of the material. The aim of this study is to propose a predictive model for the evolution of the permittivity during the chain formation, by including micro- and macroscopic phenomena. The chaining model is based on dipole-dipole interactions and the dielectric permittivity is computed through a finite element method. In parallel, an experimental study is performed with online permittivity measurements of composites during chaining. The developed model is able to predict the experimental results from 1 vol% while taking into account parameters such as the resin viscosity and permittivity and the transient evolution of the applied electric field. The formation of particle chains inside a material has applications in many domains such as electrorheological fluids, anisotropic composites, self-recovery materials etc. Such a developed model is a valuable tool for the tailoring of materials.

  19. Measurements of AC Losses and Current Distribution in Superconducting Cables

    SciTech Connect

    Nguyen, Doan A; Ashworth, Stephen P; Duckworth, Robert C; Carter, Bill; Fleshler, Steven

    2011-01-01

    This paper presents our new experimental facility and techniques to measure ac loss and current distribution between the layers for High Temperature Superconducting (HTS) cables. The facility is powered with a 45 kVA three-phase power supply which can provide three-phase currents up to 5 kA per phase via high current transformers. The system is suitable for measurements at any frequency between 20 and 500 Hz to better understand the ac loss mechanisms in HTS cables. In this paper, we will report techniques and results for ac loss measurements carried out on several HTS cables with and without an HTS shielding layer. For cables without a shielding layer, care must be taken to control the effect of the magnetic fields from return currents on loss measurements. The waveform of the axial magnetic field was also measured by a small pick-up coil placed inside a two-layer cable. The temporal current distribution between the layers can be calculated from the waveform of the axial field.

  20. Electric properties of carbon nano-onion/polyaniline composites: a combined electric modulus and ac conductivity study

    NASA Astrophysics Data System (ADS)

    Papathanassiou, Anthony N.; Mykhailiv, Olena; Echegoyen, Luis; Sakellis, Ilias; Plonska-Brzezinska, Marta E.

    2016-07-01

    The complex electric modulus and the ac conductivity of carbon nano-onion/polyaniline composites were studied from 1 mHz to 1 MHz at isothermal conditions ranging from 15 K to room temperature. The temperature dependence of the electric modulus and the dc conductivity analyses indicate a couple of hopping mechanisms. The distinction between thermally activated processes and the determination of cross-over temperature were achieved by exploring the temperature dependence of the fractional exponent of the dispersive ac conductivity and the bifurcation of the scaled ac conductivity isotherms. The results are analyzed by combining the granular metal model (inter-grain charge tunneling of extended electron states located within mesoscopic highly conducting polyaniline grains) and a 3D Mott variable range hopping model (phonon assisted tunneling within the carbon nano-onions and clusters).

  1. AC-coupled front-end for biopotential measurements.

    PubMed

    Spinelli, Enrique Mario; Pallàs-Areny, Ramon; Mayosky, Miguel Angel

    2003-03-01

    AC coupling is essential in biopotential measurements. Electrode offset potentials can be several orders of magnitude larger than the amplitudes of the biological signals of interest, thus limiting the admissible gain of a dc-coupled front end to prevent amplifier saturation. A high-gain input stage needs ac input coupling. This can be achieved by series capacitors, but in order to provide a bias path, grounded resistors are usually included, which degrade the common mode rejection ratio (CMRR). This paper proposes a novel balanced input ac-coupling network that provides a bias path without any connection to ground, thus resulting in a high CMRR. The circuit being passive, it does not limit the differential dc input voltage. Furthermore, differential signals are ac coupled, whereas common-mode voltages are dc coupled, thus allowing the closed-loop control of the dc common mode voltage by means of a driven-right-leg circuit. This makes the circuit compatible with common-mode dc shifting strategies intended for single-supply biopotential amplifiers. The proposed circuit allows the implementation of high-gain biopotential amplifiers with a reduced number of parts, thus resulting in low power consumption. An electrocardiogram amplifier built according to the proposed design achieves a CMRR of 123 dB at 50 Hz.

  2. Electrical Resistivity Measurements: a Review

    NASA Astrophysics Data System (ADS)

    Singh, Yadunath

    World-wide interest on the use of ceramic materials for aerospace and other advanced engineering applications, has led to the need for inspection techniques capable of detecting unusually electrical and thermal anomalies in these compounds. Modern ceramic materials offer many attractive physical, electrical and mechanical properties for a wide and rapidly growing range of industrial applications; moreover specific use may be made of their electrical resistance, chemical resistance, and thermal barrier properties. In this review, we report the development and various techniques for the resistivity measurement of solid kind of samples.

  3. Magnetohydrodynamic flow of generalized Maxwell fluids in a rectangular micropump under an AC electric field

    NASA Astrophysics Data System (ADS)

    Zhao, Guangpu; Jian, Yongjun; Chang, Long; Buren, Mandula

    2015-08-01

    By using the method of separation of variables, an analytical solution for the magnetohydrodynamic (MHD) flow of the generalized Maxwell fluids under AC electric field through a two-dimensional rectangular micropump is reduced. By the numerical computation, the variations of velocity profiles with the electrical oscillating Reynolds number Re, the Hartmann number Ha, the dimensionless relaxation time De are studied graphically. Further, the comparison with available experimental data and relevant researches is presented.

  4. Theoretical and experimental study of meniscus behavior under AC electric field for Electrohydrodynamic (EHD) jetting

    NASA Astrophysics Data System (ADS)

    Tran, Si Bui Quang; Byun, Doyoung

    2009-11-01

    The electrohydrodynamic (EHD) spraying technique has been utilized in applications such as inkjet printing and mass spectrometry technologies. In this paper, the role of electrical potential signals in jetting and on the oscillation of the meniscus is evaluated. The jetting and meniscus oscillation behavior are experimentally investigated under ac voltage, ac voltage superimposed on dc voltage, and pulsed dc voltage. Furthermore, the analytical simulation about the oscillation of an anchored edge hemispherical meniscus located on a conductive flat plate under a uniform ac electric field is presented. The mutual interaction between the electric field and the hydrodynamics is iteratively solved. As a result, the simulation can calculate the meniscus shapes, contours of voltage outside the meniscus and the velocity profile of liquid inside the meniscus during the period of the oscillation according to the applied frequency. Based on the present theory, one can predict the oscillation mode with a certain applied frequency. The present theory can also be applied to investigate the oscillation of a free conductive drop in a uniform ac electric field.

  5. Magneto-electric response of iron garnet film micromagnetic structure on combined action of AC and DC electric field

    NASA Astrophysics Data System (ADS)

    Koronovskyy, Vadim; Vakyla, Yuri

    2015-11-01

    Changes in the domain structure of epitaxial ferrite-garnet films under joint action of DC and AC electric fields and DC magnetic field were investigated by the optical polarimetry method. The effect of broadening of the domain wall image was found under specified combined influences. The investigations revealed that visual manifestation of the effect strongly depends on the curvature of the domain walls and the orientation of the magnetic field relative to the sample plane. Analyzing our results, we note that reaction of the domain structure to influence of external electric fields was caused by changing the magnetic anisotropy parameters of ferrite garnets in an electric field. [Figure not available: see fulltext.

  6. Lord Kelvin's atmospheric electricity measurements

    NASA Astrophysics Data System (ADS)

    Aplin, Karen; Harrison, R. Giles; Trainer, Matthew; Hough, James

    2013-04-01

    Lord Kelvin (William Thomson), one of the greatest Victorian scientists, made a substantial but little-recognised contribution to geophysics through his work on atmospheric electricity. He developed sensitive instrumentation for measuring the atmospheric electric field, including invention of a portable electrometer, which made mobile measurements possible for the first time. Kelvin's measurements of the atmospheric electric field in 1859, made during development of the portable electrometer, can be used to deduce the substantial levels of particulate pollution blown over the Scottish island of Arran from the industrial mainland. Kelvin was also testing the electrometer during the largest solar flare ever recorded, the "Carrington event" in the late summer of 1859. Subsequently, Lord Kelvin also developed a water dropper sensor, and employed photographic techniques for "incessant recording" of the atmospheric electric field, which led to the long series of measurements recorded at UK observatories for the remainder of the 19th and much of the 20th century. These data sets have been valuable in both studies of historical pollution and cosmic ray effects on atmospheric processes.

  7. Particle segregation in suspensions subject to high-gradient ac electric fields

    NASA Astrophysics Data System (ADS)

    Dussaud, Anne D.; Khusid, Boris; Acrivos, Andreas

    2000-11-01

    An experimental and theoretical study is described dealing with the dielectrophoretic motion of individual particles in a static as well as in a flowing suspension subject to high-gradient ac electric fields. The experiments were performed on very dilute suspensions of neutrally buoyant hollow ceramic spheres in a specially designed device in which the electric-field lines and the dielectrophoretic force were along the plane perpendicular to the streamlines of the main flow. Upon application of a high-gradient field (˜several kV/mm) to a quiescent suspension, the particles were found to move away from the electrodes and then to concentrate above the grounded electrodes, forming a distinct boundary between the clean fluid and the remaining suspension. This same field, when applied to a flowing suspension, caused the particles to concentrate within thin stripes parallel to the flow above the grounded electrodes and to travel with the suspending fluid within these stripes. The theoretical model for the particle motion included only the dielectrophoretic force and the viscous drag, and required no fitting parameters because the particle polarizability was calculated independently by measuring the concentration dependence of the complex permittivity of the suspension in a spatially uniform electric field of low strength (˜several V/mm). The computed particle motions and pattern formations were found to be in a good agreement with the experimental data. These results demonstrate that the expression for the dielectrophoretic force which employs the value of the particle polarization measured in fields of low strength can be used for describing the particle motions in fields of high strength. This approach enables one to model a broad range of electro-hydrodynamic phenomena in suspensions irrespective of whether or not they are perfectly insulating or perfectly conducting.

  8. Truthful Mechanisms for Combinatorial AC Electric Power Allocation

    DTIC Science & Technology

    2014-05-01

    unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 In mechanism design setting...axis and c2 on the imaginary axis. This table can be filled-up by standard dynamic programming; we de- note such a program by Multi-2DKP-Exact[·]. For...REFERENCES [1] National Electrical Code (NEC) NFPA 70-2005. [2] P. Briest, P. Krysta, and B. Vocking. Approximation techniques for utilitarian mechanism

  9. Improved transistorized AC motor controller for battery powered urban electric passenger vehicles

    NASA Technical Reports Server (NTRS)

    Peak, S. C.

    1982-01-01

    An ac motor controller for an induction motor electric vehicle drive system was designed, fabricated, tested, evaluated, and cost analyzed. A vehicle performance analysis was done to establish the vehicle tractive effort-speed requirements. These requirements were then converted into a set of ac motor and ac controller requirements. The power inverter is a three-phase bridge using power Darlington transistors. The induction motor was optimized for use with an inverter power source. The drive system has a constant torque output to base motor speed and a constant horsepower output to maximum speed. A gear shifting transmission is not required. The ac controller was scaled from the base 20 hp (41 hp peak) at 108 volts dec to an expanded horsepower and battery voltage range. Motor reversal was accomplished by electronic reversal of the inverter phase sequence. The ac controller can also be used as a boost chopper battery charger. The drive system was tested on a dynamometer and results are presented. The current-controlled pulse width modulation control scheme yielded improved motor current waveforms. The ac controller favors a higher system voltage.

  10. Lord Kelvin's atmospheric electricity measurements

    NASA Astrophysics Data System (ADS)

    Aplin, K. L.; Harrison, R. G.

    2013-09-01

    Lord Kelvin (William Thomson) made important contributions to the study of atmospheric electricity during a brief but productive period from 1859-1861. By 1859 Kelvin had recognised the need for "incessant recording" of atmospheric electrical parameters, and responded by inventing both the water dropper equaliser for measuring the atmospheric potential gradient (PG), and photographic data logging. The water dropper equaliser was widely adopted internationally and is still in use today. Following theoretical considerations of electric field distortion by local topography, Kelvin developed a portable electrometer, using it to investigate the PG on the Scottish island of Arran. During these environmental measurements, Kelvin may have unwittingly detected atmospheric PG changes during solar activity in August/September 1859 associated with the "Carrington event", which is interesting in the context of his later statements that solar magnetic influence on the Earth was impossible. Kelvin's atmospheric electricity work presents an early representative study in quantitative environmental physics, through the application of mathematical principles to an environmental problem, the design and construction of bespoke instrumentation for real world measurements and recognising the limitations of the original theoretical view revealed by experimental work.

  11. Structure in the DC and AC electric fields associated with the dayside cusp region

    NASA Technical Reports Server (NTRS)

    Maynard, N. C.

    1985-01-01

    The cusp region as seen in the AC and DC electric fields is one of intense variation. The intensity peaks within the soft particle precipitation. The only AC signal that appears to be unique to the cusp is broadband ULF-ELF magnetic noise. Other types of emissions are also found at other local times at high latitudes. The pattern of these signals, especially that of ULF-ELF broadband electrostatic noise (BEN), distinguishes the cusp region from other regions. BEN signatures are indicators of magnetosheath-like soft particle precipitation but not necessarily of open field lines. In addition, large spike-like features in the DC electric field are seen near local magnetic noon which appear to be related to the large convective electric fields that have been observed at the magnetopause. These features are not necessarily tied to convection reversals, but may appear within broader regions of zonal convective flow.

  12. ac powertrain for an electric vehicle. Phase 2 and Phase 3 final report

    SciTech Connect

    Slicker, J.M.

    1984-11-01

    This report describes work relating to Phases 2 and 3 development and testing of an ac powertrain for a 25 hp four-passenger electric vehicle. The system, which consists of a two-speed automatic mechanical transaxle, 18.6 kW ac induction traction motor, 33.6 kW inverter and overall logic controller, was installed and evaluated in a converted Mercury Lynx rolling test bed vehicle. An on-board charger and an auxiliary dc-to-dc converter were integrated into the inverter/controller package.

  13. Improved SCR ac Motor Controller for Battery Powered Urban Electric Vehicles

    NASA Technical Reports Server (NTRS)

    Latos, T. S.

    1982-01-01

    An improved ac motor controller, which when coupled to a standard ac induction motor and a dc propulsion battery would provide a complete electric vehicle power train with the exception of the mechanical transmission and drive wheels was designed. In such a system, the motor controller converts the dc electrical power available at the battery terminals to ac electrical power for the induction motor in response to the drivers commands. The performance requirements of a hypothetical electric vehicle with an upper weight bound of 1590 kg (3500 lb) were used to determine the power rating of the controller. Vehicle acceleration capability, top speed, and gradeability requisites were contained in the Society of Automotive Engineers (SAE) Schedule 227a(d) driving cycle. The important capabilities contained in this driving cycle are a vehicle acceleration requirement of 0 to 72.4 kmph (0 to 45 mph) in 28 seconds a top speed of 88.5 kmph (55 mph), and the ability to negotiate a 10% grade at 48 kmph (30 mph). A 10% grade is defined as one foot of vertical rise per 10 feet of horizontal distance.

  14. DC and ac electrical properties of the chalcogenide semiconductor Se0.9In0.1

    NASA Astrophysics Data System (ADS)

    El-Hakim, S. A.; El-Wahab, F. A.; Mohamed, A. S.; Kotkata, M. F.

    2003-07-01

    Se0.9In0.1 samples were prepared from their highly pure constituents, by ice-water quenching from the melts. Structural characterization using XRD and DTA has revealed a stable phase consisting of some crystalline clusters embedded in a glassy matrix with a single glass transition (Tg) at a temperature 320 K, an onset exothermic crystallization peak at 361 K, and a melting endotherm with a melting point at 473 K. The dc (ohmic contact region) and ac (50 Hz-80 kHz) conductivities were measured under vacuum as a function of temperature (from T < Tg down to LN2) for massive samples, 0.3-0.6 mm thick. Results of the space-charge-limited current and the electrical characteristics of both dc and ac conduction are given and discussed in the light of the temperature dependence of the conduction mechanism.

  15. Comprehensive analysis of particle motion under non-uniform AC electric fields in a microchannel.

    PubMed

    Oh, Jonghyun; Hart, Robert; Capurro, Jorge; Noh, Hongseok Moses

    2009-01-07

    AC electrokinetics is rapidly becoming a foundational tool for lab-on-a-chip systems due to its versatility and the simplicity of the components capable of generating them. Predicting the behavior of fluids and particles under non-uniform AC electric fields is important for the design of next generation devices. Though there are several important phenomena that contribute to the overall behavior of particles and fluids, current predictive techniques consider special conditions where only a single phenomenon may be considered. We report a 2D numerical simulation, using COMSOL Multiphysics, which incorporates the three major AC electrokinetic phenomena (dielectrophoresis, AC electroosmosis and electrothermal effect) and is valid for a wide range of operational conditions. Corroboration has been performed using experimental conditions that mimic those of the simulation and shows good qualitative agreement. Furthermore, a broad range of experiments has been performed using four of the most widely reported devices under varying conditions in order to show their behavior as it relates to the simulation. The large number of experimental conditions reported, together with the comprehensive numerical simulation, will help provide guidelines for scientists and engineers interested in incorporating AC electrokinetics into their lab-on-a-chip systems.

  16. Advanced AC permanent magnet axial flux disc motor for electric passenger vehicle

    NASA Technical Reports Server (NTRS)

    Kliman, G. B.

    1982-01-01

    An ac permanent magnet axial flux disc motor was developed to operate with a thyristor load commutated inverter as part of an electric vehicle drive system. The motor was required to deliver 29.8 kW (40 hp) peak and 10.4 kW (14 hp) average with a maximum speed of 11,000 rpm. It was also required to run at leading power factor to commutate the inverter. Three motors were built.

  17. Ac-loss measurement of a DyBCO-Roebel assembled coated conductor cable (RACC)

    NASA Astrophysics Data System (ADS)

    Schuller, S.; Goldacker, W.; Kling, A.; Krempasky, L.; Schmidt, C.

    2007-10-01

    Low ac-loss HTS cables for transport currents well above 1 kA are required for application in transformers and generators and are taken into consideration for future generations of fusion reactor coils. Coated conductors (CC) are suitable candidates for high field application at an operation temperature around 50-77 K, which is a crucial precondition for economical cooling costs. We prepared a short length of a Roebel bar cable made of industrial DyBCO coated conductor (Theva Company, Germany). Meander shaped tapes of 4 mm width with a twist pitch of 122 mm were cut from 10 mm wide CC tapes using a specially designed tool. Eleven of these strands were assembled to a cable. The electrical and mechanical connection of the tapes was achieved using a silver powder filled conductive epoxy resin. Ac-losses of a short sample in an external ac field were measured as a function of frequency and field amplitude in transverse and parallel field orientations. In addition, the coupling current time constant of the sample was directly measured.

  18. Electro-worming: The behaviors of Caenorhabditis (C.) elegans in DC and AC electric fields

    NASA Astrophysics Data System (ADS)

    Chuang, Han-Sheng; Raizen, David M.; Dabbish, Nooreen; Bau, Haim H.

    2011-09-01

    The video showcases how C. elegans worms respond to DC and AC electrical stimulations. Gabel et al (2007) demonstrated that in the presence of DC and low frequency AC fields, worms of stage L2 and larger propel themselves towards the cathode. Rezai et al (2010) have demonstrated that this phenomenon, dubbed electrotaxis, can be used to control the motion of worms. In the video, we reproduce Rezai's experimental results. Furthermore, we show, for the first time, that worms can be trapped with high frequency, nonuniform electric fields. We studied the effect of the electric field on the nematode as a function of field intensity and frequency and identified a range of electric field intensities and frequencies that trap worms without apparent adverse effect on their viability. Worms tethered by dielectrophoresis (DEP) avoid blue light, indicating that at least some of the nervous system functions remain unimpaired in the presence of the electric field. DEP is useful to dynamically confine nematodes for observations, sort them according to size, and separate dead worms from live ones.

  19. AC electric field induced dipole-based on-chip 3D cell rotation.

    PubMed

    Benhal, Prateek; Chase, J Geoffrey; Gaynor, Paul; Oback, Björn; Wang, Wenhui

    2014-08-07

    The precise rotation of suspended cells is one of the many fundamental manipulations used in a wide range of biotechnological applications such as cell injection and enucleation in nuclear transfer (NT) cloning. Noticeably scarce among the existing rotation techniques is the three-dimensional (3D) rotation of cells on a single chip. Here we present an alternating current (ac) induced electric field-based biochip platform, which has an open-top sub-mm square chamber enclosed by four sidewall electrodes and two bottom electrodes, to achieve rotation about the two axes, thus 3D cell rotation. By applying an ac potential to the four sidewall electrodes, an in-plane (yaw) rotating electric field is generated and in-plane rotation is achieved. Similarly, by applying an ac potential to two opposite sidewall electrodes and the two bottom electrodes, an out-of-plane (pitch) rotating electric field is generated and rolling rotation is achieved. As a prompt proof-of-concept, bottom electrodes were constructed with transparent indium tin oxide (ITO) using the standard lift-off process and the sidewall electrodes were constructed using a low-cost micro-milling process and then assembled to form the chip. Through experiments, we demonstrate rotation of bovine oocytes of ~120 μm diameter about two axes, with the capability of controlling the rotation direction and the rate for each axis through control of the ac potential amplitude, frequency, and phase shift, and cell medium conductivity. The maximum observed rotation rate reached nearly 140° s⁻¹, while a consistent rotation rate reached up to 40° s⁻¹. Rotation rate spectra for zona pellucida-intact and zona pellucida-free oocytes were further compared and found to have no effective difference. This simple, transparent, cheap-to-manufacture, and open-top platform allows additional functional modules to be integrated to become a more powerful cell manipulation system.

  20. Broadband Interferometer for Measuring Transmitted Wavefronts of Optical Bandpass Filters for HST (ACS)

    NASA Technical Reports Server (NTRS)

    Boucarut, R. A.; Leviton, D. B.

    1998-01-01

    The transmitted wavefronts of optical filters for the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) are characterized using the Wildly and Openly Modified Broadband Achromatic Twyman Green (WOMBAT) Interferometer developed in the NASA/GSFC Optics Branch's Diffraction Grating Evaluation Facility (DGEF). Because only four of thirty-three of ACS's optical bandpass filters transmit the 633 nm light of most commercial interferometers, a broadband interferometer is required to verify specified transmitted wavefront of ACS filters. WOMBAT's design is a hybrid of the BAT interferometer developed by JPL used for HST Wide Field and Planetary Camera 2 (WFPC-2) filters and a WYKO 400 phase shifting interferometer. It includes a broadband light source, monochromator, off-axis, parabolic collimating and camera mirrors, an aluminum-coated fused silica beam splitter, flat retroreflecting mirrors for the test and reference arms, and a LTV-sensitive CCD camera. An outboarded, piezo-electric phase shifter holds the flat mirror in the interferometer's reference arm. The interferometer is calibrated through interaction between the WYKO system's software and WONMAT hardware for the test wavelength of light entering the beam splitter. Phase-shifted interferograms of the filter mounted in the test arm are analyzed using WYKO's Vision' software. Filters as large as 90 mm in diameter have been measured over a wavelength range from 200 to 1100 nm with a sensitivity of lambda/200 rms at lambda = 633 nm. Results of transmitted wavefront measurements are shown for ACS fixed band pass and spatially-variable bandpass filters for a variety of wavelengths.

  1. Absorption and Attenuation Coefficients Using the WET Labs ac-s in the Mid-Atlantic Bight: Field Measurements and Data Analysis

    NASA Technical Reports Server (NTRS)

    Ohi, Nobuaki; Makinen, Carla P.; Mitchell, Richard; Moisan, Tiffany A.

    2008-01-01

    Ocean color algorithms are based on the parameterization of apparent optical properties as a function of inherent optical properties. WET Labs underwater absorption and attenuation meters (ac-9 and ac-s) measure both the spectral beam attenuation [c (lambda)] and absorption coefficient [a (lambda)]. The ac-s reports in a continuous range of 390-750 nm with a band pass of 4 nm, totaling approximately 83 distinct wavelengths, while the ac-9 reports at 9 wavelengths. We performed the ac-s field measurements at nine stations in the Mid-Atlantic Bight from water calibrations to data analysis. Onboard the ship, the ac-s was calibrated daily using Milli Q-water. Corrections for the in situ temperature and salinity effects on optical properties of water were applied. Corrections for incomplete recovery of the scattered light in the ac-s absorption tube were performed. The fine scale of spectral and vertical distributions of c (lambda) and a (lambda) were described from the ac-s. The significant relationships between a (674) and that of spectrophotometric analysis and chlorophyll a concentration of discrete water samples were observed.

  2. Propelling and spinning of microsheets in nematic liquid crystals driven by ac electric field

    NASA Astrophysics Data System (ADS)

    Rasna, M. V.; Ramudu, U. V.; Chandrasekar, R.; Dhara, Surajit

    2017-01-01

    Dynamics of microparticles in isotropic liquids by transducing the energy of an applied electric field have been studied for decades. Recently, such studies in anisotropic media like liquid crystals have opened up new perspectives in colloid science. Here, we report studies on ac-electric-field-driven dynamics of microsheets in nematic liquid crystals. In planar aligned liquid crystals, with negative dielectric anisotropy, the microsheets are propelled parallel to the director. A steady spinning of the microsheets is observed in homeotropic cells with positive dielectric anisotropy liquid crystals. The velocity of propelling and the angular frequency of spinning depends on the amplitude and the frequency of the applied electric field. The electrokinetic studies of anisotropic microparticles are important as they are potential for applications in microfluidics and in areas where the controlled transport or rotation is required.

  3. Progress on advanced dc and ac induction drives for electric vehicles

    NASA Technical Reports Server (NTRS)

    Schwartz, H. J.

    1982-01-01

    Progress is reported in the development of complete electric vehicle propulsion systems, and the results of tests on the Road Load Simulator of two such systems representative of advanced dc and ac drive technology are presented. One is the system used in the DOE's ETV-1 integrated test vehicle which consists of a shunt wound dc traction motor under microprocessor control using a transistorized controller. The motor drives the vehicle through a fixed ratio transmission. The second system uses an ac induction motor controlled by transistorized pulse width modulated inverter which drives through a two speed automatically shifted transmission. The inverter and transmission both operate under the control of a microprocessor. The characteristics of these systems are also compared with the propulsion system technology available in vehicles being manufactured at the inception of the DOE program and with an advanced, highly integrated propulsion system upon which technology development was recently initiated.

  4. Electric field and losses at AC self field mode in MF composites

    SciTech Connect

    Fukui, S.; Hlasnik, I.; Tsukamoto, O.; Amemiya, N. ); Polak, M.; Kottman, P. . Inst. of Electrical Engineering)

    1994-07-01

    Studies of the current-voltage characteristics of typical superconducting wires under static and dynamic conditions up to 50 Hz frequency have revealed much higher instantaneous local loss power densities in an external DC magnetic field than those which occur by magnetization in a transverse AC magnetic field. In this paper, the measured loss characteristics are compared with theoretical ones derived from the critical state model, and the self field AC loss are also estimated. Possible errors that can result by applying the critical state model are discussed.

  5. Keratinocyte galvanotaxis in combined DC and AC electric fields supports an electromechanical transduction sensing mechanism.

    PubMed

    Hart, Francis X; Laird, Mhairi; Riding, Aimie; Pullar, Christine E

    2013-02-01

    Sedentary keratinocytes at the edge of a skin wound migrate into the wound, guided by the generation of an endogenous electric field (EF) generated by the collapse of the transepithelial potential. The center of the wound quickly becomes more negative than the surrounding tissue and remains the cathode of the endogenous EF until the wound is completely re-epithelialized. This endogenous guidance cue can be studied in vitro. When placed in a direct current (DC) EF of physiological strength, 100 V/m, keratinocytes migrate directionally toward the cathode in a process known as galvanotaxis. Although a number of membrane-bound (e.g., epidermal growth factor receptor (EGFR), integrins) and cytosolic proteins (cAMP, ERK, PI3K) are known to play a role in the downstream signaling mechanisms underpinning galvanotaxis, the initial sensing mechanism for this response is not understood. To investigate the EF sensor, we studied the migration of keratinocytes in a DC EF of 100 V/m, alternating current (AC) EFs of 40 V/m at either 1.6 or 160 Hz, and combinations of DC and AC EFs. In the AC EFs alone, keratinocytes migrated randomly. The 1.6 Hz AC EF combined with the DC EF suppressed the direction of migration but had no effect on speed. In contrast, the 160 Hz AC EF combined with the DC EF did not affect the direction of migration but increased the migration speed compared to the DC EF alone. These results can be understood in terms of an electromechanical transduction model, but not an electrodiffusion/osmosis or a voltage-gated channel model.

  6. Evaluation of semiconductor devices for Electric and Hybrid Vehicle (EHV) ac-drive applications, volume 1

    NASA Technical Reports Server (NTRS)

    Lee, F. C.; Chen, D. Y.; Jovanovic, M.; Hopkins, D. C.

    1985-01-01

    The results of evaluation of power semiconductor devices for electric hybrid vehicle ac drive applications are summarized. Three types of power devices are evaluated in the effort: high power bipolar or Darlington transistors, power MOSFETs, and asymmetric silicon control rectifiers (ASCR). The Bipolar transistors, including discrete device and Darlington devices, range from 100 A to 400 A and from 400 V to 900 V. These devices are currently used as key switching elements inverters for ac motor drive applications. Power MOSFETs, on the other hand, are much smaller in current rating. For the 400 V device, the current rating is limited to 25 A. For the main drive of an electric vehicle, device paralleling is normally needed to achieve practical power level. For other electric vehicle (EV) related applications such as battery charger circuit, however, MOSFET is advantageous to other devices because of drive circuit simplicity and high frequency capability. Asymmetrical SCR is basically a SCR device and needs commutation circuit for turn off. However, the device poses several advantages, i.e., low conduction drop and low cost.

  7. Evaluation of DC electric field distribution of PPLP specimen based on the measurement of electrical conductivity in LN2

    NASA Astrophysics Data System (ADS)

    Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Lee, Jong-Geon; Cho, Jeon-Wook; Ryoo, Hee-Suk; Lee, Bang-Wook

    2013-11-01

    High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN2). Electrical conductivity of PPLP in LN2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN2 were presented in this paper. Based on the experimental works, DC electric field distribution of PPLP specimen was fully analyzed considering the steady state and the transient state of DC. Consequently, it was possible to determine the electric field distribution characteristics considering different DC applying stages including DC switching on, DC switching off and polarity reversal conditions.

  8. Calibration-free electrical conductivity measurements for highly conductive slags

    SciTech Connect

    MACDONALD,CHRISTOPHER J.; GAO,HUANG; PAL,UDAY B.; VAN DEN AVYLE,JAMES A.; MELGAARD,DAVID K.

    2000-05-01

    This research involves the measurement of the electrical conductivity (K) for the ESR (electroslag remelting) slag (60 wt.% CaF{sub 2} - 20 wt.% CaO - 20 wt.% Al{sub 2}O{sub 3}) used in the decontamination of radioactive stainless steel. The electrical conductivity is measured with an improved high-accuracy-height-differential technique that requires no calibration. This method consists of making continuous AC impedance measurements over several successive depth increments of the coaxial cylindrical electrodes in the ESR slag. The electrical conductivity is then calculated from the slope of the plot of inverse impedance versus the depth of the electrodes in the slag. The improvements on the existing technique include an increased electrochemical cell geometry and the capability of measuring high precision depth increments and the associated impedances. These improvements allow this technique to be used for measuring the electrical conductivity of highly conductive slags such as the ESR slag. The volatilization rate and the volatile species of the ESR slag measured through thermogravimetric (TG) and mass spectroscopy analysis, respectively, reveal that the ESR slag composition essentially remains the same throughout the electrical conductivity experiments.

  9. AC electrical transport properties and current-voltage hysteresis behavior of PVA-CNT nanocomposite film

    NASA Astrophysics Data System (ADS)

    Das, Amit Kumar; Sinha, Subhojyoti; Meikap, Ajit Kumar

    2015-06-01

    Polyvinyl alcohol (PVA) - Carbon nanotube (CNT) composite has been prepared and its electric modulus, ac conductivity, impedance spectroscopy and current-voltage characteristics have been studied, at and above room temperature, to understand the prevailing charge transport mechanism. Non-Debye type relaxation behavior was observed with activation energy of 1.27 eV whereas correlated barrier hopping was found to be the dominant charge transport mechanism with maximum barrier height of 48.7 meV above room temperature. The sample, under ±80 V applied voltage, exhibits hysteresis behavior in its current - voltage characteristics.

  10. Development of dielectrophoresis separator with an insulating porous membrane using DC-Offset AC Electric Fields.

    PubMed

    Hakoda, Masaru

    2016-09-01

    Our previous studies revealed that the dielectrophoresis method is effective for separating cells having different dielectric properties. The purpose of this study was to evaluate the separation characteristics of two kinds of cells by direct current (DC) voltage offset/alternating current (AC) voltage using an insulating porous membrane dielectrophoretic separator. The separation device gives dielectrophoretic (DEP) force and electrophoretic (EP) force to dispersed particles by applying the DC-offset AC voltage. This device separates cells of different DEP properties by adopting a structure in which only the parallel plate electrodes and the insulating porous membrane are disposed in the flow path through which the cell-suspension flows. The difference in the retention ratios of electrically homogeneous 4.5 μm or 20.0 μm diameter standard particles was a maximum of 82 points. Furthermore, the influences of the AC voltage or offset voltage on the retention ratios of mouse hybridoma 3-2H3 cells and horse red blood cells (HRBC) were investigated. The difference in the retention ratio of the two kinds of cells was a maximum of 56 points. The separation efficiency of this device is expected to be improved by changing the device shape, number of pores, and pore placement. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1292-1300, 2016.

  11. Frequency dependent electrical measurements of amorphous GeSbSe chalcogenide thin films

    SciTech Connect

    Mirsaneh, M.; Furman, E.; Ryan, Joseph V.; Lanagan, M. T.; Pantano, C. G.

    2010-03-22

    A commercial bulk chalcogenide glass (Ge28Sb12Se60) was used as a source to fabricate amorphous thin films via thermal evaporation technique. At low frequencies (1 MHz) impedance spectroscopy was performed to measure electrical properties. To measure ac conductivity at microwave frequencies, a split resonance cavity technique was applied for which a model based on parallel arrangement of substrate and film capacitors was developed. This model was used to extract tan8 and ac conductivity of the films. Microwave ac conductivity was correlated with the extrapolated low frequency conductivity data confirming applicability of the universal law commonly observed in amorphous semiconductors.

  12. AC electrical breakdown phenomena of epoxy/layered silicate nanocomposite in needle-plate electrodes.

    PubMed

    Park, Jae-Jun; Lee, Jae-Young

    2013-05-01

    Epoxy/layered silicate nanocomposite for the insulation of heavy electric equipments were prepared by dispersing 1 wt% of a layered silicate into an epoxy matrix with a homogenizing mixer and then AC electrical treeing and breakdown tests were carried out. Wide-angle X-ray diffraction (WAXD) analysis and transmission electron microscopy (TEM) observation showed that nano-sized monolayers were exfoliated from a multilayered silicate in the epoxy matrix. When the nano-sized silicate layers were incorporated into the epoxy matrix, the breakdown rate in needle-plate electrode geometry was 10.6 times lowered than that of the neat epoxy resin under the applied electrical field of 520.9 kV/mm at 30 degrees C, and electrical tree propagated with much more branches in the epoxy/layered silicate nanocomposite. These results showed that well-dispersed nano-sized silicate layers retarded the electrical tree growth rate. The effects of applied voltage and ambient temperature on the tree initiation, growth, and breakdown rate were also studied, and it was found that the breakdown rate was largely increased, as the applied voltage and ambient temperature increased.

  13. Experimental and theoretical study of AC electrical conduction mechanisms of semicrystalline parylene C thin films.

    PubMed

    Kahouli, Abdelkader; Sylvestre, Alain; Jomni, Fethi; Yangui, Béchir; Legrand, Julien

    2012-01-26

    The electrical conduction mechanisms of semicrystalline thermoplastic parylene C (-H(2)C-C(6)H(3)Cl-CH(2)-)(n) thin films were studied in large temperature and frequency regions. The alternative current (AC) electrical conduction in parylene C is governed by two processes which can be ascribed to a hopping transport mechanism: correlated barrier hopping (CBH) model at low [77-155 K] and high [473-533 K] temperature and the small polaron tunneling mechanism (SPTM) from 193 to 413 K within the framework of the universal law of dielectric response. The conduction mechanism is explained with the help of Elliot's theory, and the Elliot's parameters are determined. From frequency- and temperature-conductivity characteristics, the activation energy is found to be 1.27 eV for direct current (DC) conduction interpreted in terms of ionic conduction mechanism. The power law dependence of AC conductivity is interpreted in terms of electron hopping with a density N(E(F)) (~10(18) eV cm(-3)) over a 0.023-0.03 eV high barrier across a distance of 1.46-1.54 Å.

  14. Effect of interaction between AC electric field and phonon oscillation of metal cluster on tip-growth of carbon nanotube

    NASA Astrophysics Data System (ADS)

    Saeidi, Mohammadreza

    2015-06-01

    The paper reports effect of interaction between AC electric field and metal cluster sitting at tip end of the carbon nanotube (CNT) on CNT tip-growth in CVD theoretically. For this purpose, a theoretical model based on phonon oscillations of the metal catalyst and influence of AC electric field on these oscillations is presented. Results show that there is an optimum AC electric field which optimizes growth of ultra-long CNTs. Then it is demonstrated that, in comparison with CNTs in the absence of field, CNTs under optimum electric field grow more. In addition, relation between optimum temperature and amplitude of AC electric field is investigated and it is shown that increasing electric field leads to higher optimum temperature. Finally, Investigation of effect of catalyst type on optimum electric field demonstrates the optimum field for various catalysts is different due to their different characteristics including van der Waals interaction with carbon, atomic mass and number of free charge carriers per each atom. All results are discussed and interpreted.

  15. DC-AC Cascaded H-Bridge Multilevel Boost Inverter With No Inductors for Electric/Hybrid Electric Vehicle Applications

    SciTech Connect

    Tolbert, Leon M; Ozpineci, Burak; Du, Zhong; Chiasson, John N

    2009-01-01

    This paper presents a cascaded H-bridge multilevel boost inverter for electric vehicle (EV) and hybrid EV (HEV) applications implemented without the use of inductors. Currently available power inverter systems for HEVs use a dc-dc boost converter to boost the battery voltage for a traditional three-phase inverter. The present HEV traction drive inverters have low power density, are expensive, and have low efficiency because they need a bulky inductor. A cascaded H-bridge multilevel boost inverter design for EV and HEV applications implemented without the use of inductors is proposed in this paper. Traditionally, each H-bridge needs a dc power supply. The proposed design uses a standard three-leg inverter (one leg for each phase) and an H-bridge in series with each inverter leg which uses a capacitor as the dc power source. A fundamental switching scheme is used to do modulation control and to produce a five-level phase voltage. Experiments show that the proposed dc-ac cascaded H-bridge multilevel boost inverter can output a boosted ac voltage without the use of inductors.

  16. Fiber-optic sensors for aerospace electrical measurements: An update

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Rose, A. H.; Tang, D.; Day, G. W.

    1991-01-01

    Fiber-optic sensors are being developed for electrical current, voltage, and power measurements in aerospace applications. These sensors are presently designed to cover ac frequencies from 60 Hz to 20 kHz. The current sensor, based on the Faraday effect in optical fiber, is in advanced development after some initial testing. Concentration is on packaging methods and ways to maintain consistent sensitivity with changes in temperature. The voltage sensor, utilizing the Pockels effect in a crystal, has excelled in temperature tests. This paper reports on the development of these sensors, the results of evaluation, improvements now in progress, and the future direction of the work.

  17. Design of Low Temperature AC Susceptibility Measurement Scheme for Molecular Magnets

    NASA Astrophysics Data System (ADS)

    Korenblit, Simcha; Moon, Byoung; Lee, Yoonseok; Sultan, Reza

    2006-03-01

    AC susceptibility is one of the most important physical properties in many materials such as magnetic materials and superconductors. Although there are many commercial AC susceptibility measurement systems which cover a broad range of temperatures, it is still a daunting task to extend their measurement range into the low millikelvins. We are currently developing a low temperature AC susceptometer for the mK range. As a part of this effort, we have developed a versatile low-cost computer controlled coil-winder to make various types of coils. We have designed primary and secondary coils and wound them using the machine, and performed characterization of the AC susceptometer. In this presentation, I will explain the basics of magnetic susceptibility, its measurement, design considerations for building an AC magnetic susceptometer, and discuss the details of an actual apparatus designed and realized by the authors.

  18. Structural, Optical and AC Electrical Properties of Ce3+-Doped TiO2-SiO2 Matrices

    NASA Astrophysics Data System (ADS)

    Vidyadharan, Viji; Vasudevan, Prathibha; Karthika, S.; Joseph, Cyriac; Unnikrishnan, N. V.; Biju, P. R.

    2015-08-01

    We report the structural, photoluminescence and alternating current (AC) electrical properties of Ce3+-doped titanosilicate matrices prepared by nonhydrolytic sol-gel method, with different annealing temperatures. The structural characterization of the prepared samples was done by x-ray diffraction, energy dispersive spectrum and Fourier transform infrared spectroscopy measurements. The thermal stability of the prepared matrices was studied by the differential scanning calorimetric analysis. The photoluminescence spectrum shows two luminescence bands centered at 360 nm and 464 nm corresponding to the transitions 2D3/2 to 2F7/2 and 2F5/2, respectively. The dielectric responses of the samples were investigated for the frequency range 1 kHz-3 MHz at room temperature. The variation of AC conductivity, real part of dielectric constant ɛ' and imaginary part of dielectric constant ɛ″ with frequency were also studied. The Cole-Cole parameters were calculated and the semicircles observed in the plots indicate a single relaxation process which can be modelled by an equivalent parallel resistor-capacitor circuit.

  19. Hall-effect based semi-fast AC on-board charging equipment for electric vehicles.

    PubMed

    Milanés-Montero, María Isabel; Gallardo-Lozano, Javier; Romero-Cadaval, Enrique; González-Romera, Eva

    2011-01-01

    The expected increase in the penetration of electric vehicles (EV) and plug-in hybrid electric vehicles (PHEV) will produce unbalanced conditions, reactive power consumption and current harmonics drawn by the battery charging equipment, causing a great impact on the power quality of the future smart grid. A single-phase semi-fast electric vehicle battery charger is proposed in this paper. This ac on-board charging equipment can operate in grid-to-vehicle (G2V) mode, and also in vehicle-to-grid (V2G) mode, transferring the battery energy to the grid when the vehicle is parked. The charger is controlled with a Perfect Harmonic Cancellation (PHC) strategy, contributing to improve the grid power quality, since the current demanded or injected has no harmonic content and a high power factor. Hall-effect current and voltage transducers have been used in the sensor stage to carry out this control strategy. Experimental results with a laboratory prototype are presented.

  20. Hall-Effect Based Semi-Fast AC On-Board Charging Equipment for Electric Vehicles

    PubMed Central

    Milanés-Montero, María Isabel; Gallardo-Lozano, Javier; Romero-Cadaval, Enrique; González-Romera, Eva

    2011-01-01

    The expected increase in the penetration of electric vehicles (EV) and plug-in hybrid electric vehicles (PHEV) will produce unbalanced conditions, reactive power consumption and current harmonics drawn by the battery charging equipment, causing a great impact on the power quality of the future smart grid. A single-phase semi-fast electric vehicle battery charger is proposed in this paper. This ac on-board charging equipment can operate in grid-to-vehicle (G2V) mode, and also in vehicle-to-grid (V2G) mode, transferring the battery energy to the grid when the vehicle is parked. The charger is controlled with a Perfect Harmonic Cancellation (PHC) strategy, contributing to improve the grid power quality, since the current demanded or injected has no harmonic content and a high power factor. Hall-effect current and voltage transducers have been used in the sensor stage to carry out this control strategy. Experimental results with a laboratory prototype are presented. PMID:22163697

  1. Concentration-tuned interactions and structures in flowing suspensions under a gradient AC electric field

    NASA Astrophysics Data System (ADS)

    Tada, Shigeru; Qiu, Zhiyong; Shen, Yan

    2016-11-01

    In this study, numerical simulations of suspensions of Al2O3 particles in corn oil at various volume fractions were performed to explore the mechanisms involved in the electro-mechanical behavior of positive polarized particles suspended in an insulated suspending medium traveling through a rotating flow channel while exposed to a nonuniform AC electric field. A theoretical model was developed to simulate the trajectories of individual particles under the action of dielectrophoretic (DEP), dipole-dipole interparticle, viscous, and gravitational forces in a laminar flow. The results demonstrated that particles began to aggregate along the edges of electrodes with electric field application. New particles coming from more distant regions then gradually joined the vertices of particle aggregates, leading to the growth of chain-like clusters along the electric field gradient. Predictions showed good agreement with the results observed in a previous experiment. The new findings of this study are that the DEP force always tends to confine particles near the electrode edges, whereas the clustering of particles on the electrodes arises from the competition between particle interaction due to the DEP force and the long-range dipole-dipole interparticle interaction with neighboring particles. This process became more apparent with higher volume fractions of particle.

  2. Time dependence of electrical bioimpedance on porcine liver and kidney under a 50 Hz ac current

    NASA Astrophysics Data System (ADS)

    Spottorno, J.; Multigner, M.; Rivero, G.; Álvarez, L.; de la Venta, J.; Santos, M.

    2008-03-01

    The purpose of this work is to study the changes of the bioimpedance from its 'in vivo' value to the values measured in a few hours after the excision from the body. The evolution of electrical impedance with time after surgical extraction has been studied on two porcine organs: the liver and the kidney. Both in vivo and ex vivo measurements of electrical impedance, measuring its real and imaginary components, have been performed. The in vivo measurements have been carried out with the animal anaesthetized. The ex vivo measurements have been made more than 2 h after the extraction of the organ. The latter experiment has been carried out at two different stabilized temperatures: at normal body temperature and at the standard preservation temperature for transplant surgery. The measurements show a correlation between the biological evolution and the electrical bioimpedance of the organs, which increases from its in vivo value immediately after excision, multiplying its value by 2 in a few hours.

  3. Time dependence of electrical bioimpedance on porcine liver and kidney under a 50 Hz ac current.

    PubMed

    Spottorno, J; Multigner, M; Rivero, G; Alvarez, L; de la Venta, J; Santos, M

    2008-03-21

    The purpose of this work is to study the changes of the bioimpedance from its 'in vivo' value to the values measured in a few hours after the excision from the body. The evolution of electrical impedance with time after surgical extraction has been studied on two porcine organs: the liver and the kidney. Both in vivo and ex vivo measurements of electrical impedance, measuring its real and imaginary components, have been performed. The in vivo measurements have been carried out with the animal anaesthetized. The ex vivo measurements have been made more than 2 h after the extraction of the organ. The latter experiment has been carried out at two different stabilized temperatures: at normal body temperature and at the standard preservation temperature for transplant surgery. The measurements show a correlation between the biological evolution and the electrical bioimpedance of the organs, which increases from its in vivo value immediately after excision, multiplying its value by 2 in a few hours.

  4. Electrical Characteristics, Electrode Sheath and Contamination Layer Behavior of a Meso-Scale Premixed Methane-Air Flame Under AC/DC Electric Fields

    NASA Astrophysics Data System (ADS)

    Chen, Qi; Yan, Limin; Zhang, Hao; Li, Guoxiu

    2016-05-01

    Electrical characteristics of a nozzle-attached meso-scale premixed methane-air flame under low-frequency AC (0-4300 V, 0-500 Hz) and DC (0-3300 V) electric fields were studied. I-V curves were measured under different experimental conditions to estimate the magnitude of the total current 100-102 μA, the electron density 1015-1016 m-3 and further the power dissipation ≤ 0.7 W in the reaction zone. At the same time, the meso-scale premixed flame conductivity 10-4-10-3 Ω-1·m-1 as a function of voltage and frequency was experimentally obtained and was believed to represent a useful order-of magnitude estimate. Moreover, the influence of the collision sheath relating to Debye length (31-98 μm) and the contamination layer of an active electrode on measurements was discussed, based on the combination of simulation and theoretical analysis. As a result, the electrode sheath dimension was evaluated to less than 0.5 mm, which indicated a complex effect of the collision sheath on the current measurements. The surface contamination effect of an active electrode was further analyzed using the SEM imaging method, which showed elements immigration during the contamination layer formation process. supported by National Natural Science Foundation of China (No. 51376021), and the Fundamental Research Fund for Major Universities (No. 2013JBM079)

  5. Studies on the activation energy from the ac conductivity measurements of rubber ferrite composites containing manganese zinc ferrite

    NASA Astrophysics Data System (ADS)

    Hashim, Mohd.; Alimuddin; Kumar, Shalendra; Shirsath, Sagar E.; Mohammed, E. M.; Chung, Hanshik; Kumar, Ravi

    2012-11-01

    Manganese zinc ferrites (MZF) have resistivities between 0.01 and 10 Ω m. Making composite materials of ferrites with either natural rubber or plastics will modify the electrical properties of ferrites. The moldability and flexibility of these composites find wide use in industrial and other scientific applications. Mixed ferrites belonging to the series Mn(1-x)ZnxFe2O4 were synthesized for different ‘x’ values in steps of 0.2, and incorporated in natural rubber matrix (RFC). From the dielectric measurements of the ceramic manganese zinc ferrite and rubber ferrite composites, ac conductivity and activation energy were evaluated. A program was developed with the aid of the LabVIEW package to automate the measurements. The ac conductivity of RFC was then correlated with that of the magnetic filler and matrix by a mixture equation which helps to tailor properties of these composites.

  6. Microfabricated AC impedance sensor

    DOEpatents

    Krulevitch, Peter; Ackler, Harold D.; Becker, Frederick; Boser, Bernhard E.; Eldredge, Adam B.; Fuller, Christopher K.; Gascoyne, Peter R. C.; Hamilton, Julie K.; Swierkowski, Stefan P.; Wang, Xiao-Bo

    2002-01-01

    A microfabricated instrument for detecting and identifying cells and other particles based on alternating current (AC) impedance measurements. The microfabricated AC impedance sensor includes two critical elements: 1) a microfluidic chip, preferably of glass substrates, having at least one microchannel therein and with electrodes patterned on both substrates, and 2) electrical circuits that connect to the electrodes on the microfluidic chip and detect signals associated with particles traveling down the microchannels. These circuits enable multiple AC impedance measurements of individual particles at high throughput rates with sufficient resolution to identify different particle and cell types as appropriate for environmental detection and clinical diagnostic applications.

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

    PubMed

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

    2010-07-01

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

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

    SciTech Connect

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

    2010-07-15

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  10. Ac Permeability Measurement for Inter- and Intragrain Critical Current Densities in Oxide Superconductors

    NASA Astrophysics Data System (ADS)

    Matsushita, Teruo; Ni, Baorong

    1989-03-01

    A simple measuring method to discriminate between inter- and intragrain current densities in oxide superconductors under given magnetic fields and temperatures is proposed. This is a measurement of the imaginary part of the ac permeability or susceptibility as a function of the ac field amplitude. In this method, the analysis used to derive the penetration depth of the ac field in Campbell’s method or the waveform analysis method is not necessary. This method is useful when the value of the penetration field into the grains and that into the bulk specimen are remarkably different.

  11. Quantitative Thermal Microscopy Measurement with Thermal Probe Driven by dc+ac Current

    NASA Astrophysics Data System (ADS)

    Bodzenta, Jerzy; Juszczyk, Justyna; Kaźmierczak-Bałata, Anna; Firek, Piotr; Fleming, Austin; Chirtoc, Mihai

    2016-07-01

    Quantitative thermal measurements with spatial resolution allowing the examination of objects of submicron dimensions are still a challenging task. The quantity of methods providing spatial resolution better than 100 nm is very limited. One of them is scanning thermal microscopy (SThM). This method is a variant of atomic force microscopy which uses a probe equipped with a temperature sensor near the apex. Depending on the sensor current, either the temperature or the thermal conductivity distribution at the sample surface can be measured. However, like all microscopy methods, the SThM gives only qualitative information. Quantitative measuring methods using SThM equipment are still under development. In this paper, a method based on simultaneous registration of the static and the dynamic electrical resistances of the probe driven by the sum of dc and ac currents, and examples of its applications are described. Special attention is paid to the investigation of thin films deposited on thick substrates. The influence of substrate thermal properties on the measured signal and its dependence on thin film thermal conductivity and film thickness are analyzed. It is shown that in the case where layer thicknesses are comparable or smaller than the probe-sample contact diameter, a correction procedure is required to obtain actual thermal conductivity of the layer. Experimental results obtained for thin SiO2 and BaTiO_{3 }layers with thicknesses in the range from 11 nm to 100 nm are correctly confirmed with this approach.

  12. Correlation of AC Loss Data from Magnetic Susceptibility Measurements with YBCO Film Quality (Postprint)

    DTIC Science & Technology

    2012-02-01

    excimer laser operating at the KrF, 248 nm , wavelength. Substrates included LaAlO3 ( 100 ) and SrTiO3 ( 100 ) single crystal substrates as well as buffered...AFRL-RZ-WP-TP-2012-0100 CORRELATION OF AC LOSS DATA FROM MAGNETIC SUSCEPTIBILITY MEASUREMENTS WITH YBCO FILM QUALITY (POSTPRINT) Paul N...CORRELATION OF AC LOSS DATA FROM MAGNETIC SUSCEPTIBILITY MEASUREMENTS WITH YBCO FILM QUALITY (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT

  13. Measuring Electrical Resistivity Of Compacted Powder

    NASA Technical Reports Server (NTRS)

    Shlichta, Paul J.

    1991-01-01

    Slightly modified micrometer used in conjunction with special cup to measure electrical resistance of specimen of powder as function of packing fraction. Powder pressed between anvils of micrometer, which make electrical contact with specimen. Device used in manufacturing batteries to determine effective electrical conductivities of powders loaded into plastic sheets to make battery substrates. Coupled with good mathematical description of expected conductivity of particulate composite as function of packing density. Also serves as tool for evaluating conductivity of dispersed phase, as well as evaluating electrical resistances of interparticle contacts.

  14. Electrorheology of Dispersions of BaxSr(1-x)TiO3 in Silicone Oil Under AC or DC Electric Field

    NASA Astrophysics Data System (ADS)

    Luz, Glauber M. S.; Bombard, Antonio J. F.; Brito, Silvio L. M.; Gouvêa, Douglas; Vieira, Sheila L.

    2012-07-01

    Electrorheology (ER) of ferroelectric materials such as nanometric BaTiO3 is still not fully understood. In this paper, nanoparticles of BaxSr(1-x)TiO3 (where x = 0.8, 0.9 or 1.0) were synthesized using the method of Pechini, calcinated at 950°C, and after, lixiviated under pH 1 or pH 5. A controlled stress rheometer (MCR-301) was used to make the ER characterization of dispersions made of Bax Ti1-xO3 in silicone oil (30% w/w), where (a) shear stress as a function of DC electric field (under constant shear rate) or (b) shear stress as a function of shear rate (under constant AC or DC electric field) were measured. We observed that electrophoresis occurred under electric field DC, creating a concentration gradient which induced phase separation in ER fluid. On the other hand, under AC fields above 1 kV/mm, the ER effect is stronger than for DC field, and almost without electrophoresis. Furthermore, there is an AC frequency, dependent on the disperse phase, where the ER effect has a maximum.

  15. AC loss measurements in HTS coil assemblies with hybrid coil structures

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenan; Long, Nicholas J.; Staines, Mike; Badcock, Rodney A.; Bumby, Chris W.; Buckley, Robert G.; Amemiya, Naoyuki

    2016-09-01

    Both AC loss and wire cost in coil windings are critical factors for high temperature superconductor (HTS) AC machinery applications. We present AC loss measurement results in three HTS coil assemblies at 77 K and 65 K which have a hybrid coil structure comprising one central winding (CW) and two end windings (EWs) wound with ReBCO and BSCCO wires with different self-field I c values at 77 K. All AC loss results in the coil assemblies are hysteretic and the normalized AC losses in the coil assemblies at different temperatures can be scaled with the I c value of the coil assemblies. The normalised results show that AC loss in a coil assembly with BSCCO CW can be reduced by using EWs wound with high I c ReBCO wires, whilst further AC loss reduction can be achieved by replacing the BSCCO CW with ReBCO CW. The results imply that a flexible hybrid coil structure is possible which considers both AC loss and wire cost in coil assemblies.

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

    NASA Technical Reports Server (NTRS)

    Pfaff, R.

    1999-01-01

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

  17. Human aquaporin 4 gating dynamics in dc and ac electric fields: A molecular dynamics study

    NASA Astrophysics Data System (ADS)

    Garate, J.-A.; English, Niall J.; MacElroy, J. M. D.

    2011-02-01

    Water self-diffusion within human aquaporin 4 has been studied using molecular dynamics (MD) simulations in the absence and presence of external ac and dc electric fields. The computed diffusive (pd) and osmotic (pf) permeabilities under zero-field conditions are (0.718 ± 0.24) × 10-14 cm3 s-1 and (2.94 ± 0.47) × 10-14 cm3 s-1, respectively; our pf agrees with the experimental value of (1.50 ± 0.6) × 10-14 cm3 s-1. A gating mechanism has been proposed in which side-chain dynamics of residue H201, located in the selectivity filter, play an essential role. In addition, for nonequilibrium MD in external fields, it was found that water dipole orientation within the constriction region of the channel is affected by electric fields (e-fields) and that this governs the permeability. It was also found that the rate of side-chain flipping motion of residue H201 is increased in the presence of e-fields, which influences water conductivity further.

  18. Tuning polymer nanocomposite morphology: AC electric field manipulation of epoxy-montmorillonite (clay) suspensions

    SciTech Connect

    Koerner,H.; Jacobs, D.; Tomlin, D.; Busbee, J.; Vaia, R.

    2004-01-01

    The next revolutionary leap forward for polymer nano-'composites' necessitates the development of tools to transform the currently random or ill-defined nanoscale morphologies into compositionally and spatially engineered hierarchal structures, paralleling that underpinning conventional continuous fiber reinforced composites and enabling experimental verification of morphology-mechanical property correlations. Here in, utilization of AC electric fields of modest strength (1-10 V/micron) is demonstrated as a general approach to align organically modified layered silicates (OLS) parallel to the electric field-enhancing CTE, modulus and optical clarity in the reinforced direction. Interfacial polarization arising from electrophoric motion of the organic-modifier on the layer surface induces a dipole parallel to the plane of the layer, which couples to the external field. Comparably, application of a static magnetic field (0.5-2 T) induces alignment of the layers parallel or perpendicular to the field, depending on the chemical composition of the OLS. The impact of field magnitude, field frequency, dielectric permittivity and magnetic permeability of the system is discussed to elucidate the molecular characteristics of induced dipole formation and establish the limits of the process.

  19. Tuning Polymer Nanocomposite Morphology: Magnetic and AC Electric Field Manipulation of Epoxy - Montmorillonite (Clay) Suspensions

    NASA Astrophysics Data System (ADS)

    Vaia, Richard; Koerner, Hilmar; Jacobs, J. David; Busbee, John; Hampton, Edwin; Dean, Derrick

    2004-03-01

    The next revolutionary leap forward for polymer nano-'composites' necessitates the development of tools to transform the currently random or ill-defined nanoscale morphologies into compositionally and spatially engineered hierarchal structures, paralleling that underpinning conventional continuous fiber reinforced composites and enabling experimental verification of morphology-mechanical property correlations. Here in, utilization of AC electric fields of modest strength (1-10 V/micron) is demonstrated as a general approach to align organically modified layered silicates (OLS) parallel to the electric field - enhancing CTE, modulus and optical clarity in the reinforced direction. Interfacial polarization arising from electrophoric motion of the organic-modifier on the layer surface induces a dipole parallel to the plane of the layer, which couples to the external field. Comparably, application of a static magnetic field (0.5-2 T) induces alignment of the layers parallel or perpendicular to the field, depending on the chemical composition of the OLS. The impact of field magnitude, field frequency, dielectric permittivity and magnetic permeability of the system is discussed to elucidate the molecular characteristics of induced dipole formation and establish the limits of the process.

  20. Developing passive MEMS DC/AC current sensor applicable to two-wire appliances with high measurement accuracy

    NASA Astrophysics Data System (ADS)

    Wang, Dong F.; Li, Xiaodong; Xian, Weikang; Liu, Huan; Liu, Xin

    2016-10-01

    A passive MEMS DC/AC current sensor with high measurement accuracy, accomplished by the methodology combining both the "stress-equilibrium" solution and the "position-free" solution, was proposed for measuring electricity consumption of household equipment and Information and Communication Technology devices. For the "stress-equilibrium" solution, slots between two adjacent piezoelectric plates are implemented to minimize the distribution difference of the uneven stress close to the fixed end. The measurement error caused by the uneven stress distribution is decreased from 9% to 4% for ten-piezoelectric-plates and from 8% to 0.5% for three-piezoelectric-plates, respectively. For the "position-free" consideration, an array comprised of four piezoelectric cantilevers is proposed to eliminate the positional error resulted by the uneven magnetic field distribution generated by the test object of electric currents. And the solution is proofed to be an effective method to eliminate the positional error by theoretical and simulation analysis. In light of the above preliminary results, the passive MEMS DC/AC current sensor is believed to be useful to achieve high measurement accuracy via integrating the "stress-equilibrium" and the "position-free" designs. The newly proposed current sensor with high measurement accuracy is applicable to two-wire appliance cord without using any cord separator like that used in Hall-effect based sensor.

  1. Sub-micrometer particles produced by a low-powered AC electric arc in liquids.

    PubMed

    Jaworski, Jacek A; Fleury, Eric

    2012-01-01

    The article presents the report of the production of composites of sub-micrometer metal particles in matrix consisted of the metal compounds by means of an AC electric arc in water and paraffin solutions using electrodes carbon-metal and metal-metal (metal: Ni, Fe, Co, Cu). The advantage of this method is the low electric power (from 5 to 10 W) needed in comparison to standard DC arc-discharge methods (0.8 to 3 kW). This method enables the production of particles from conductive material also in wide range of temperature and in solvent which could be either transparent to light or opaque. Moreover the solvent can be electrolyte or insulating liquid. The microstructure of the composite layer was investigated by scanning electron microscopy (SEM), Electron Probe Microanalysis (EPMA) and X-ray. During particles production in water metal oxides were created. Additionally using cobalt-copper, nickel-copper as couple electrodes, insoluble in water copper (II) hydroxide crystal grains were created additionally which crystals shape was depended on transition metal. For iron-copper couple electrodes system the copper (II) hydroxide was not formed. Experiments with sequence production of Ni and Fe particles with C electrode assisting in molten paraffin let to obtain both Ni and Fe particles surrounded by paraffin. After solidification the material was insulator but if locally magnetic field influenced on the liquid solution in that place after solidification a new composite was created which was electric current conductor with resistivity around 0.1 omega x m, was attracted by magnetic field and presented magneto resistance around 0.4% in changing magnetic field in a range 150 mT. After mixing the concentrated paraffin with normal paraffin resistivity of the mixture increased and it became photosensitive and created small voltage under light influence.

  2. Electron-radiation effects on the ac and dc electrical properties and unpaired electron densities of three aerospace polymers

    NASA Technical Reports Server (NTRS)

    Long, Sheila Ann T.; Long, Edward R., Jr.; Ries, Heidi R.; Harries, Wynford L.

    1986-01-01

    The effects of gigarad-level total absorbed doses from 1-MeV electrons on the post-irradiation alternating-current (ac) and direct-current (dc) electrical properties and the unpaired electron densities have been studied for Kapton, Ultem, and Mylar. The unpaired electron densities (determined from electron paramagnetic resonance spectroscopy) and the dc electrical conductivities of the irradiated materials were monitored as functions of time following the exposures to determine their decay characteristics at room temperature. The elevated-temperature ac electrical dissipations of the Ultem and Mylar were affected by the radiation. The dc conductivity of the Kapton increased by five orders of magnitude, while the dc conductivities of the Ultem and Mylar increased by less than an order of magnitude, due to the radiation. The observed radiation-generated changes in the ac electrical dissipations are explained in terms of known radiation-generated changes in the molecular structures of the three materials. A preliminary model relating the dc electrical conductivity and the unpaired electron density in the Kapton is proposed.

  3. Rotating Capacitor Measures Steady Electric Fields

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

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

  4. Transport AC losses of Ag-sheathed Bi-2223 tapes with different twist-pitch using electrical methods

    NASA Astrophysics Data System (ADS)

    Jang, M.-H.; Wong-Ng, W.

    2006-01-01

    A series of Bi-2223 ([Bi, Pb]:Sr:Ca:Cu:O = 2:2:2:3) tapes with 37 superconducting core filaments was investigated in an attempt to correlate critical current and alternating current (AC) losses with twist-pitch. The twist-pitch of these multi-filamentary tapes which were produced by the powder-in-(Ag)tube (PIT) method varies from 8, 10, 13, 30, 50, 70 mm to ∞ mm (non-twist). Critical current (Ic) measurements which were conducted in zero field by a four-probe method under liquid-nitrogen temperature showed that Ic is greater in the non-twist filament than that in twisted filaments. Among these tapes, three (twist-pitch of 10, 13, and 70 mm) were selected for AC loss experiments under a time-varying transport current. The results of AC loss measurements in general agree with that of the AC loss simulation using the ellipse model of the Norris equation. Simulation results show that the hysteretic AC loss is lowest in the non-twist tape and increases as the twist-pitch decreases. A much greater loss was found in tapes with small twist-pitch, i.e. 10 and 8 mm. Among different possible loss contributions to the total AC losses, the hysteretic loss was determined to be the main source. In addition, microstructural damage of tapes with small twist-pitch appears to contribute to the overall AC losses as well.

  5. Magneto-electric Effect and Dielectric Susceptibility Measurement Technique at Very Low Temperature

    NASA Astrophysics Data System (ADS)

    Xia, J. S.; Yin, L.; Sullivan, N. S.; Zapf, V. S.; Paduan-Filho, A.

    2016-12-01

    We report the design and operation of a new device for measuring the magneto-electric effects, dielectric susceptibility, and electrical resistance of materials at very low temperatures (below 10 mK). The unique feature of the device is the immersion of the sample in liquid 3He which is cooled with a large (25 m2) surface area sintered silver heat exchanger connected to the nuclear stage of a demagnetization refrigerator. In addition to a DC applied magnetic field (up to 16 T), an AC magnetic field is provided by a Helmholtz coil located outside the sample. With this design the magnetic field-dependent electric susceptibilities, and the DC and AC resistance can be measured simultaneously. The details and performance of the device are discussed, and measurements on interesting new materials such as quantum organic magnets are presented.

  6. Linear optics measurements and corrections using an AC dipole in RHIC

    SciTech Connect

    Wang, G.; Bai, M.; Yang, L.

    2010-05-23

    We report recent experimental results on linear optics measurements and corrections using ac dipole. In RHIC 2009 run, the concept of the SVD correction algorithm is tested at injection energy for both identifying the artificial gradient errors and correcting it using the trim quadrupoles. The measured phase beatings were reduced by 30% and 40% respectively for two dedicated experiments. In RHIC 2010 run, ac dipole is used to measure {beta}* and chromatic {beta} function. For the 0.65m {beta}* lattice, we observed a factor of 3 discrepancy between model and measured chromatic {beta} function in the yellow ring.

  7. The Wechsler ACS Social Perception Subtest: A Preliminary Comparison with Other Measures of Social Cognition

    ERIC Educational Resources Information Center

    Kandalaft, Michelle R.; Didehbani, Nyaz; Cullum, C. Munro; Krawczyk, Daniel C.; Allen, Tandra T.; Tamminga, Carol A.; Chapman, Sandra B.

    2012-01-01

    Relative to other cognitive areas, there are few clinical measures currently available to assess social perception. A new standardized measure, the Wechsler Advanced Clinical Solutions (ACS) Social Perception subtest, addresses some limitations of existing measures; however, little is known about this new test. The first goal of this investigation…

  8. Electric field measurements with stratospheric balloons

    NASA Technical Reports Server (NTRS)

    Iversen, I. B.

    1989-01-01

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

  9. Measuring Electrical Current: The Roads Not Taken

    NASA Astrophysics Data System (ADS)

    Greenslade, Thomas B.

    2011-05-01

    Recently I wrote about the standard Weston meter movement1,2 that is at the heart of all modern analogue current measurements. Now I will discuss other techniques used to measure electric current that, despite being based on valid physical principles, are largely lost in technological history.

  10. Measuring Electrical Current: The Roads Not Taken

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    2011-01-01

    Recently I wrote about the standard Weston meter movement, that is at the heart of all modern analogue current measurements. Now I will discuss other techniques used to measure electric current that, despite being based on valid physical principles, are largely lost in technological history.

  11. AC losses in high pressure synthesized MgB2 bulk rings measured by a transformer method

    NASA Astrophysics Data System (ADS)

    Meerovich, V.; Sokolovsky, V.; Prikhna, T.; Gawalek, W.; Habisreuther, T.

    2013-03-01

    Recently developed manufacturing technologies use high pressure and various doping additions to prepare bulk MgB2-based materials with a high critical current density measured by the magnetization method. We use a contactless transformer method, which is based on studying the superconductor response to an induced transport current, to measure AC losses in bulk MgB2 rings synthesized under high pressure. The obtained dependence of the losses on the primary current (applied magnetic field) is fitted by a power law with an exponent of ˜2.1 instead of the cubic dependence predicted by Bean’s model and power law electric field-current density (E-J) characteristics with a large exponent. An unusually strong dependence of the AC losses on the frequency is also observed. It is shown that the E-J characteristic of bulk MgB2 is well fitted by the dependence used in the extended critical state model based on account of the viscous vortex motion in the flux flow regime. Numerical simulation using this E-J characteristic gives current and frequency AC loss dependences that agree well with the experimental results.

  12. Human/Nonhuman Primate AC-PC Ratio - Considerations for Translational Brain Measurements

    PubMed Central

    Fiandaca, Massimo S.; Salegio, Ernesto Aguilar; Yin, Dali; Richardson, R. Mark; Valles, Francisco E.; Larson, Paul S.; Starr, Philip A.; Lonser, Russell R.; Bankiewicz, Krystof S.

    2011-01-01

    This comparative magnetic resonance imaging (MRI) analysis evaluated the ratio of AC-PC (anterior commissure to posterior commissure) distance measures in selected groups of humans and nonhuman primates (NHPs). An understanding of the basis of this ratio between primate species may allow more accurate translation of NHP stereotactic targeting measurements to upcoming human trials. MRI datasets of adult humans [n=21], and juvenile and adult NHPs (Macaca fascicularis [n=40], and Macaca mulatta [n=32]), were evaluated in a mid-sagittal plane to obtain the AC-PC distance measure for each examined subject. Two trained evaluators, blinded to each other’s results, carried out three separate measurements of the AC-PC length for each subject. Each observer carried out measurements of the entire dataset [n=93] before repeating the measurements two additional times. Previous dataset measures were not available for review at the time of subsequent measures. Inter- and intra-observer variabilities were not statistically significant. Minimal intraspecies variation was found in the AC-PC measurement of our human and NHP groups. We found significant interspecies differences, however, more between humans and NHPs, and less between the NHP groups. Regression analysis confirms the strong linear relationship of AC-PC distance based primarily on species in our study groups. Human/NHP AC-PC ratios varied between 2.1 to 2.3 based on the compared NHP species groups. We conclude that the scale differences in brain measurements between NHPs and humans described in this study allows improved translation of stereotactic targeting coordinates in future human clinical trials, which may lead to improved efficacy and safety. PMID:21185868

  13. Mesoscopic turbulence and local order in Janus particles self-propelling under an ac electric field

    NASA Astrophysics Data System (ADS)

    Nishiguchi, Daiki; Sano, Masaki

    2015-11-01

    To elucidate mechanisms of mesoscopic turbulence exhibited by active particles, we experimentally study turbulent states of nonliving self-propelled particles. We realize an experimental system with dense suspensions of asymmetrical colloidal particles (Janus particles) self-propelling on a two-dimensional surface under an ac electric field. Velocity fields of the Janus particles in the crowded situation can be regarded as a sort of turbulence because it contains many vortices and their velocities change abruptly. Correlation functions of their velocity field reveal the coexistence of polar alignment and antiparallel alignment interactions, which is considered to trigger mesoscopic turbulence. Probability distributions of local order parameters for polar and nematic orders indicate the formation of local clusters with particles moving in the same direction. A broad peak in the energy spectrum of the velocity field appears at the spatial scales where the polar alignment and the cluster formation are observed. Energy is injected at the particle scale and conserved quantities such as energy could be cascading toward the larger clusters.

  14. Magnetospheric electric field measurements during sudden commencements

    NASA Technical Reports Server (NTRS)

    Aggson, T. L.; Skillman, T. L.

    1973-01-01

    Direction measurements of electric fields were made in the outer magnetosphere during two sudden commencements in 1972. These measurements were observed with the double floating probe experiment carried aboard the IMP 6 satellite. The initial variations of the measured electric field consisted of an increase from a background of about 1 mv/meter to some 10 mv/meter at about 7 rE (earth radi) and to some 4 mv/meter at 3 rE. These initial electric field disturbances were longitudinal, oriented counter clockwise about an axis pointed north. A solution of Maxwell's third equation is derived for these measurements using a quasi-static version of Mead's model of the magnetosphere B (t). This solution seems to describe well the magnitude and direction of the initial perturbation of the electric field vectors observed during these two sudden commencements. After the initial increase, the measured electric field rings several times with periods of the order of minutes. This observed oscillatory behavior correlates with magnetic observatory records taken near the foot of the magetic field line passing through the satellite.

  15. Performance criteria guideline for three explosion protection methods of electrical equipment rated up to 15,000 volts AC

    NASA Technical Reports Server (NTRS)

    Linley, L. J.; Luper, A. B.; Dunn, J. H.

    1982-01-01

    The Bureau of Mines, U.S. Department of the Interior, is reviewing explosion protection methods for use in gassy coal mines. This performance criteria guideline is an evaluation of three explosion protection methods of machines electrically powered with voltages up to 15,000 volts ac. A sufficient amount of basic research has been accomplished to verify that the explosion proof and pressurized enclosure methods can provide adequate explosion protection with the present state of the art up to 15,000 volts ac. This routine application of the potted enclosure as a stand alone protection method requires further investigation or development in order to clarify performance criteria and verification certification requirements. An extensive literature search, a series of high voltage tests, and a design evaluation of the three explosion protection methods indicate that the explosion proof, pressurized, and potted enclosures can all be used to enclose up to 15,000 volts ac.

  16. Measurements of AC Loss In Second-Generation HTS Tapes in a DC Magnetic Field

    NASA Astrophysics Data System (ADS)

    Osofsky, M. S.; Soulen, R. J.; Gubser, D. U.; Datta, T.

    2008-03-01

    The successful application of superconductivity to motors and other power system components depends on the characterization and subsequent minimization of the ac loss in the superconductor used for fabrication of the component. The superconductive component, excited by an ac power source, may be exposed to large dc magnetic fields and/or ac fields. To further complicate the situation, the transport properties of the tapes are strongly dependent on the angle between the applied field and the YBCO c-axis (normal to the tape surface). We report on measurements of the transport ac loss of a YBaCuO tape at 65 K, at several frequencies, in applied dc fields of 1-3 T with the field parallel and perpendicular to the tape normal.

  17. Electric field measurements from Halley, Antarctica

    NASA Astrophysics Data System (ADS)

    Nicoll, Keri; Harrison, R. Giles

    2016-04-01

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

  18. Controller for controlling operation of at least one electrical load operating on an AC supply, and a method thereof

    DOEpatents

    Cantin, Luc; Deschenes, Mario; D'Amours, Mario

    1995-08-15

    A controller is provided for controlling operation of at least one electrical load operating on an AC supply having a typical frequency, the AC supply being provided via power transformers by an electrical power distribution grid. The controller is associated with the load and comprises an input interface for coupling the controller to the grid, a frequency detector for detecting the frequency of the AC supply and producing a signal indicative of the frequency, memory modules for storing preprogrammed commands, a frequency monitor for reading the signal indicative of the frequency and producing frequency data derived thereof, a selector for selecting at least one of the preprogrammed commands with respect to the frequency data, a control unit for producing at least one command signal representative of the selected preprogrammed commands, and an output interface including a device responsive to the command signal for controlling the load. Therefore, the load can be controlled by means of the controller depending on the frequency of the AC supply.

  19. Contact-independent electrical conductance measurement

    DOEpatents

    Mentzel, Tamar S.; MacLean, Kenneth; Kastner, Marc A.; Ray, Nirat

    2017-01-24

    Electrical conductance measurement system including a one-dimensional semiconducting channel, with electrical conductance sensitive to electrostatic fluctuations, in a circuit for measuring channel electrical current. An electrically-conductive element is disposed at a location at which the element is capacitively coupled to the channel; a midpoint of the element aligned with about a midpoint of the channel, and connected to first and second electrically-conductive contact pads that are together in a circuit connected to apply a changing voltage across the element. The electrically-conductive contact pads are laterally spaced from the midpoint of the element by a distance of at least about three times a screening length of the element, given in SI units as (K.di-elect cons..sub.0/e.sup.2D(E.sub.F)).sup.1/2, where K is the static dielectric constant, .di-elect cons..sub.0 is the permittivity of free space, e is electron charge, and D(E.sub.F) is the density of states at the Fermi energy for the element.

  20. Electric Field Quantitative Measurement System and Method

    NASA Technical Reports Server (NTRS)

    Generazio, Edward R. (Inventor)

    2016-01-01

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

  1. AC Inductive Measurement of Intergrain and Intragrain Currents in High-Tc Oxide Superconductors

    NASA Astrophysics Data System (ADS)

    Ni, Baorong; Munakata, Toshiyuki; Matsushita, Teruo; Iwakuma, Masataka; Funaki, Kazuo; Takeo, Masakatsu; Yamafuji, Kaoru

    1988-09-01

    Bulk intergrain current and closed intragrain current in sintered Y-Ba-Cu-O superconductors were measured at 77 K by using an ac inductive method. These currents can be separated because of the large difference in penetrating rates of the magnetic flux into specimens with respect to the ac field amplitude. The obtained intergrain current density agreed approximately with critical current density measured resistively. The closed intragrain current density amounted to 4.3× 108 A/m2 at B{=}0.5 T and decreased gradually with increasing magnetic field. The present results show that the ac inductive measurement is one of the available nondestructive methods to characterize sintered oxide specimens.

  2. Calorimetric AC loss measurement of MgB2 superconducting tape in an alternating transport current and direct magnetic field

    NASA Astrophysics Data System (ADS)

    See, K. W.; Xu, X.; Horvat, J.; Cook, C. D.; Dou, S. X.

    2012-11-01

    Applications of MgB2 superconductors in electrical engineering have been widely reported, and various studies have been made to define their alternating current (AC) losses. However, studies on the transport losses with an applied transverse DC magnetic field have not been conducted, even though this is one of the favored conditions in applications of practical MgB2 tapes. Methods and techniques used to characterize and measure these losses have so far been grouped into ‘electrical’ and ‘calorimetric’ approaches with external conditions set to resemble the application conditions. In this paper, we present a new approach to mounting the sample and employ the calorimetric method to accurately determine the losses in the concurrent application of AC transport current and DC magnetic fields that are likely to be experienced in practical devices such as generators and motors. This technique provides great simplification compared to the pickup coil and lock-in amplifier methods and is applied to a long length (˜10 cm) superconducting tape. The AC loss data at 20 and 30 K will be presented in an applied transport current of 50 Hz under external DC magnetic fields. The results are found to be higher than the theoretical predictions because of the metallic fraction of the tape that contributes quite significantly to the total losses. The data, however, will allow minimization of losses in practical MgB2 coils and will be used in the verification of numerical coil models.

  3. Recent advances in the mitigation of AC voltages occurring in pipelines located close to electric transmission lines

    SciTech Connect

    Southey, R.D.; Dawalibi, F.P. ); Vukonich, W. )

    1994-04-01

    In joint-use corridors where both pipelines and AC electric transmission lines are present, a portion of the energy contained in the electromagnetic field surrounding the electric transmission lines is captured by each pipeline, resulting in induced AC voltages which vary in magnitude throughout the length of each pipeline. During a fault on any of the transmission lines, energization of the earth by supporting structures near the fault can result in large voltages appearing locally between the earth and the steel wall of any nearby pipeline. Some form of mitigation is usually required to reduce these voltages to acceptable levels for the protection of personnel and of the pipeline itself. This paper presents a new mitigation design approach which not only reduces AC voltages effectively and economically, but also provides cathodic protection for the protected pipeline. Performance of this new mitigation method is illustrated with results from computer simulations, which show how important it is to have an accurate electrical model of the soil structure in any interference study. Results from large-scale mitigation design studies performed for ANR Pipeline Company and other gas transmission companies are presented.

  4. Electrode Response in Seismo-Electric Measurements

    NASA Astrophysics Data System (ADS)

    Dietrich, M.; Devi, M. S.; Cougoulat, G.; Garambois, S.

    2014-12-01

    Seismo-electric measurements consist in recording the transient electric fields generated by seismic waves propagating in fluid-filled porous or fractured media. These electric fields are usually measured by voltage differences between two electrodes. Unfortunately, the electrode spacing and their locations on the ground surface have a direct influence on the signal-to-noise ratio of the measurements, on the recorded waveforms and on their arrival times. Using a filter theory approach and full waveform numerical simulations of the coupled seismic and electromagnetic (EM) wave propagation in porous media, we show that the co-seismic electric arrivals and the small-amplitude EM interface response can be severely distorted and/or attenuated by conventional surface electrode layouts. To this end, we have computed synthetic electrograms providing the electric potential, to allow us to determine voltage differences between two arbitrary locations of electrodes. Unlike the low-pass filter obtained by connecting two geophones in series, the filter associated with a voltage difference is shown to be a band-pass filter. As a result, not only horizontally and obliquely propagating waves but also vertically propagating waves undergo selective frequency attenuation in the 0-150 Hz frequency band used in field measurements. It also turns out that electrode spacing cannot be optimized to enhance the electric signature of typical seismic reflections and EM interface response, neither with horizontal dipoles nor with reasonably sized vertical dipoles. To circumvent this problem, we consider arrangements of 3 and 5 electrodes analogous to multilayer capacitors in electronics. We show that such arrangements are ideally described by low-pass filters preserving the quasi-plane waves corresponding to the EM interface response. However, in reality, these benefits are challenged by the imperfect coupling between the electrodes and the ground, represented by an electrode contact resistance

  5. High-Resolution ac Measurements of the Hall Effect in Organic Field-Effect Transistors

    NASA Astrophysics Data System (ADS)

    Chen, Y.; Yi, H. T.; Podzorov, V.

    2016-03-01

    We describe a high resolving power technique for Hall-effect measurements, efficient in determining Hall mobility and carrier density in organic field-effect transistors and other low-mobility systems. We utilize a small low-frequency ac magnetic field (Brms<0.25 T ) and a phase-sensitive (lock-in) detection of Hall voltage, with the necessary corrections for Faraday induction. This method significantly enhances the signal-to-noise ratio and eliminates the necessity of using high magnetic fields in Hall-effect studies. With the help of this method, we are able to obtain the Hall mobility and carrier density in organic transistors with a mobility as low as μ ˜0.3 cm2 V-1 s-1 by using a compact desktop apparatus and low magnetic fields. We find a good agreement between Hall-effect and electric-field-effect measurements, indicating that, contrary to the common belief, certain organic semiconductors with mobilities below 1 cm2 V-1 s-1 can still exhibit a fully developed, band-semiconductor-like Hall effect, with the Hall mobility and carrier density matching those obtained in longitudinal transistor measurements. This suggests that, even when μ <1 cm2 V-1 s-1 , charges in organic semiconductors can still behave as delocalized coherent carriers. This technique paves the way to ubiquitous Hall-effect studies in a wide range of low-mobility materials and devices, where it is typically very difficult to resolve the Hall effect even in very high dc magnetic fields.

  6. Optical Overlay Versus Electric Probe Measurement

    NASA Astrophysics Data System (ADS)

    Mortensen, Keith Y.; Blachowicz, Betty A.

    1989-07-01

    The predominant method used in the past for the measurement of overlay has been manual reading of the "optical vernier." This method can be reasonably precise and has been sufficient for most semiconductor products made up until a few short years ago. The ever-increasing number of masking levels below 1.5-micron Minimum Feature Size (MFS) requires large statistical bases of overlay measurements with quick turnaround. No longer are 4 to 10 sites per wafer sufficient to accurately judge overlay, nor can we afford to wait 20 minutes for an operator to manually read these verniers. For years, Perkin-Elmer has used a unique and proprietary electrical probe system custom-built by Perkin-Elmer prior to the introduction of the Micralign Model 500. Capable of gathering large amounts of data and performing statistical analysis, it became a standard for overlay evaluation within Perkin-Elmer. An alternative to electrical probe is automated optical measurement. One such system is the Perkin-Elmer OMSTM. This system has the advantage of being "non destructive" and can be used to measure actual product wafers in process. This paper will provide a performance comparison of both techniques, optical and electrical. Using a mask with both optical and electrical probe patterns, a series of wafers was exposed. The evaluation compares accuracy, precision, speed, and statistical capabilities.

  7. Development of Low-Frequency AC Voltage Measurement System Using Single-Junction Thermal Converter

    NASA Astrophysics Data System (ADS)

    Amagai, Yasutaka; Nakamura, Yasuhiro

    Accurate measurement of low-frequency AC voltage using a digital multimeter at frequencies of 4-200Hz is a challenge in the mechanical engineering industry. At the National Metrology Institute of Japan, we developed a low-frequency AC voltage measurement system for calibrating digital multimeters operating at frequencies down to 1 Hz. The system uses a single-junction thermal converter and employs a theoretical model and a three-parameter sine wave fitting algorithm based on the least-square (LS) method. We calibrated the AC voltage down to 1Hz using our measurement system and reduced the measurement time compared with that using thin-film thermal converters. Our measurement results are verified by comparison with those of a digital sampling method using a high-resolution analog-to-digital converter; our data are in agreement to within a few parts in 105. Our proposed method enables us to measure AC voltage with an uncertainty of 25 μV/V (k = 1) at frequencies down to 4 Hz and a voltage of 10 V.

  8. Incorporating residential AC load control into ancillary service markets: Measurement and settlement

    SciTech Connect

    Bode, Josh L.; Sullivan, Michael J.; Berghman, Dries; Eto, Joseph H.

    2013-05-01

    Many pre-existing air conditioner load control programs can provide valuable operational flexibility but have not been incorporated into electricity ancillary service markets or grid operations. Multiple demonstrations have shown that residential air conditioner (AC) response can deliver resources quickly and can provide contingency reserves. A key policy hurdle to be overcome before AC load control can be fully incorporated into markets is how to balance the accuracy, cost, and complexity of methods available for the settlement of load curtailment. Overcoming this hurdle requires a means for assessing the accuracy of shorter-term AC load control demand reduction estimation approaches in an unbiased manner. This paper applies such a method to compare the accuracy of approaches varying in cost and complexity ? including regression analysis, load matching and control group approaches ? using feeder data, household data and AC end-use data. We recommend a practical approach for settlement, relying on an annually updated set of tables, with pre-calculated reduction estimates. These tables allow users to look up the demand reduction per device based on daily maximum temperature, geographic region and hour of day, simplifying settlement and providing a solution to the policy problem presented in this paper.

  9. Stratospheric electric field measurements with transmediterranean balloons

    NASA Astrophysics Data System (ADS)

    de La Morena, B. A.; Alberca, L. F.; Curto, J. J.; Holzworth, R. H.

    1993-01-01

    The horizontal component of the stratospheric electric field was measured using a balloon in the ODISEA Campaign of Transmediterranean Balloon Program. The balloon flew between Trapani (Sicily) and El Arenosillo (Huelva, Spain) along the 39 deg N parallel at a height between 34 and 24 km. The high values found for the field on fair-weather and its quasi-turbulent variation, both in amplitude and direction, are difficult to explain with the classical electric field source. A new source, first described by Holzworth (1989), is considered as possibly causing them.

  10. Fiber - Optic Devices as Temperature Sensors for Temperature Measurements in AC Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Rablau, Corneliu; Lafrance, Joseph; Sala, Anca

    2007-10-01

    We report on the investigation of several fiber-optic devices as potential sensors for temperature measurements in AC magnetic fields. Common temperature sensors, such as thermocouples, thermistors or diodes, will create random and/or systematic errors when placed in a magnetic field. A DC magnetic field is susceptible to create a systematic offset to the measurement, while in an AC magnetic field of variable frequency random errors which cannot be corrected for can also be introduced. Fiber-Bragg-gratings and thin film filters have an inherent temperature dependence. Detrimental for their primary applications, the same dependence allows one to use such devices as temperature sensors. In an AC magnetic field, they present the advantage of being immune to electromagnetic interference. Moreover, for fiber-Bragg-gratings, the shape factor and small mass of the bare-fiber device make it convenient for temperature measurements on small samples. We studied several thin-film filters and fiber-Bragg-gratings and compared their temperature measurement capabilities in AC magnetic fields of 0 to 150 Gauss, 0 to 20 KHz to the results provided by off-the-shelf thermocouples and thermistor-based temperature measurement systems.

  11. Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

    DOEpatents

    Vail III, William Banning; Momii, Steven Thomas

    2003-06-10

    A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

  12. Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

    DOEpatents

    Vail, III, William Banning; Momii, Steven Thomas

    2001-01-01

    A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

  13. Electrical voltages and resistances measured to inspect metallic cased wells and pipelines

    DOEpatents

    Vail, III, William Banning; Momii, Steven Thomas

    2000-01-01

    A cased well in the earth is electrically energized with A.C. current. Voltages are measured from three voltage measurement electrodes in electrical contact with the interior of the casing while the casing is electrically energized. In a measurement mode, A.C. current is conducted from a first current carrying electrode within the cased well to a remote second current carrying electrode located on the surface of the earth. In a calibration mode, current is passed from the first current carrying electrode to a third current carrying electrode located vertically at a different position within the cased well, where the three voltage measurement electrodes are located vertically in between the first and third current carrying electrodes. Voltages along the casing and resistances along the casing are measured to determine wall thickness and the location of any casing collars present so as to electrically inspect the casing. Similar methods are employed to energize a pipeline to measure the wall thickness of the pipeline and the location of pipe joints to electrically inspect the pipeline.

  14. A multichannel continuously selectable multifrequency electrical impedance spectroscopy measurement system.

    PubMed

    Hartov, A; Mazzarese, R A; Reiss, F R; Kerner, T E; Osterman, K S; Williams, D B; Paulsen, K D

    2000-01-01

    There is increasing evidence that alterations in the electrical property spectrum of tissues below 10 MHz is diagnostic for tissue pathology and/or pathophysiology. Yet, the complexity associated with constructing a high-fidelity multichannel, multifrequency data acquisition instrument has limited widespread development of spectroscopic electrical impedance imaging concepts. To contribute to the relatively sparse experience with multichannel spectroscopy systems this paper reports on the design, realization and evaluation of a prototype 32-channel instrument. The salient features of the system include a continuously selectable driving frequency up to 1 MHz, either voltage or current source modes of operation and simultaneous measurement of both voltage and current on each channel in either of these driving configurations. Comparisons of performance with recently reported fixed-frequency systems is favorable. Volts dc (VDC) signal-to-noise ratios of 75-80 dB are achieved and the noise floor for ac signals is near 100 dB below the signal strength of interest at 10 kHz and 60 dB down at 1 MHz. The added benefit of being able to record multispectral information on source and sense signal amplitudes and phases has also been realized. Phase-sensitive detection schemes and multiperiod undersampling techniques have been deployed to ensure measurement fidelity over the full bandwidth of system operation.

  15. Traveling-wave electrokinetic micropumps: velocity, electrical current, and impedance measurements.

    PubMed

    García-Sánchez, P; Ramos, A; Green, N G; Morgan, H

    2008-09-02

    An array of microelectrodes covered in an electrolyte and energized by a traveling-wave potential produces net movement of the fluid. Arrays of platinum microelectrodes of two different characteristic sizes have been studied. For both sizes of arrays, at low voltages (<2 V pp) the electrolyte flow is in qualitative agreement with the linear theory of ac electroosmosis. At voltages above a threshold, the direction of fluid flow is reversed. The electrical impedance of the electrode-electrolyte system was measured after the experiments, and changes in the electrical properties of the electrolyte were observed. Measurements of the electrical current during pumping of the electrolyte are also reported. Transient behaviors in both electrical current and fluid velocity were observed. The Faradaic currents probably generate conductivity gradients in the liquid bulk, which in turn give rise to electrical forces. These effects are discussed in relation to the fluid flow observations.

  16. Causal Analysis of the Inadvertent Contact with an Uncontrolled Electrical Hazardous Energy Source (120 Volts AC)

    SciTech Connect

    David E. James; Dennis E. Raunig; Sean S. Cunningham

    2014-10-01

    On September 25, 2013, a Health Physics Technician (HPT) was performing preparations to support a pneumatic transfer from the HFEF Decon Cell to the Room 130 Glovebox in HFEF, per HFEF OI 3165 section 3.5, Field Preparations. This activity involves an HPT setting up and climbing a portable ladder to remove the 14-C meter probe from above ball valve HBV-7. The HPT source checks the meter and probe and then replaces the probe above HBV-7, which is located above Hood ID# 130 HP. At approximately 13:20, while reaching past the HBV-7 valve position indicator switches in an attempt to place the 14-C meter probe in the desired location, the HPT’s left forearm came in contact with one of the three sets of exposed terminals on the valve position indication switches for HBV 7. This resulted in the HPT receiving an electrical shock from a 120 Volt AC source. Upon moving the arm, following the electrical shock, the HPT noticed two exposed electrical connections on a switch. The HPT then notified the HFEF HPT Supervisor, who in turn notified the MFC Radiological Controls Manager and HFEF Operations Manager of the situation. Work was stopped in the area and the hazard was roped off and posted to prevent access to the hazard. The HPT was escorted by the HPT Supervisor to the MFC Dispensary and then preceded to CFA medical for further evaluation. The individual was evaluated and released without any medical restrictions. Causal Factor (Root Cause) A3B3C01/A5B2C08: - Knowledge based error/Attention was given to wrong issues - Written Communication content LTA, Incomplete/situation not covered The Causal Factor (root cause) was attention being given to the wrong issues during the creation, reviews, verifications, and actual performance of HFEF OI-3165, which covers the need to perform the weekly source check and ensure placement of the probe prior to performing a “rabbit” transfer. This resulted in the hazard not being identified and mitigated in the procedure. Work activities

  17. Electric Field Effects in RUS Measurements

    SciTech Connect

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

    2009-09-21

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

  18. Electric field effects in RUS measurements.

    PubMed

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

    2010-02-01

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

  19. Road load simulator tests of the Gould phase 1 functional model silicon controlled rectifier ac motor controller for electric vehicles

    NASA Technical Reports Server (NTRS)

    Gourash, F.

    1984-01-01

    The test results for a functional model ac motor controller for electric vehicles and a three-phase induction motor which were dynamically tested on the Lewis Research Center road load simulator are presented. Results show that the controller has the capability to meet the SAE-J227a D cycle test schedule and to accelerate a 1576-kg (3456-lb) simulated vehicle to a cruise speed of 88.5 km/hr (55 mph). Combined motor controller efficiency is 72 percent and the power inverter efficiency alone is 89 percent for the cruise region of the D cycle. Steady state test results for motoring, regeneration, and thermal data obtained by operating the simulator as a conventional dynamometer are in agreement with the contractor's previously reported data. The regeneration test results indicate that a reduction in energy requirements for urban driving cycles is attainable with regenerative braking. Test results and data in this report serve as a data base for further development of ac motor controllers and propulsion systems for electric vehicles. The controller uses state-of-the-art silicon controlled rectifier (SCR) power semiconductors and microprocessor-based logic and control circuitry. The controller was developed by Gould Laboratories under a Lewis contract for the Department of Energy's Electric and Hybrid Vehicle program.

  20. An effective electrical sensing scheme using AC electrothermal flow on a biosensor platform based on a carbon nanotube network

    NASA Astrophysics Data System (ADS)

    Lee, Won Cheol; Lee, Hoseok; Lim, Jaeheung; Park, Young June

    2016-11-01

    We report a simple and efficient electrical sensing scheme that can be used to overcome the "diffusion limit" of affinity-based biosensors by incorporating the structural advantage of a concentric electrode biosensor platform and the microstirring effect of AC electrothermal flow (ACEF). To prove the effect of ACEF on the biosensor performance, we performed both simulations and experiments for the detection of cardiac troponin-I, which is a biomarker for acute myocardial infarction. The finite element simulation results indicate that AC bias to the electrode (which has a concentric structure in our device) can induce fast convection flow, which facilitates the transport of the target molecules to the binding region located between the two electrodes. In our device, the channel region made of a carbon nanotube network decorated with gold nanoparticles, which act as the attaching sites of the probe molecules, is used as a highly sensitive electrical channel. We find that the electrical sensing method exhibited extremely fast sensing speeds compared with those under no bias (diffusion-limited) conditions.

  1. Effective method to measure back emfs and their harmonics of permanent magnet ac motors

    NASA Astrophysics Data System (ADS)

    Jiang, Q.; Bi, C.; Lin, S.

    2006-04-01

    As the HDD spindle motors become smaller and smaller, the back electromotive forces (emfs) measurement faces the new challenges due to their low inertias and small sizes. This article proposes a novel method to measure the back emfs and their harmonic components of PM ac motors only through a freewheeling procedure. To eliminate the influence of the freewheeling deceleration, the phase flux linkages are employed to obtain the back emf amplitudes and phases of the fundamental and harmonic components by using finite Fourier series analysis. The proposed method makes the freewheeling measurement of the back emfs and their harmonics accurate and fast. It is especially useful for the low inertia PM ac motors, such as spindle motors for small form factor HDDs.

  2. Module Twelve: Series AC Resistive-Reactive Circuits; Basic Electricity and Electronics Individualized Learning System.

    ERIC Educational Resources Information Center

    Bureau of Naval Personnel, Washington, DC.

    The module covers series circuits which contain both resistive and reactive components and methods of solving these circuits for current, voltage, impedance, and phase angle. The module is divided into six lessons: voltage and impedance in AC (alternating current) series circuits, vector computations, rectangular and polar notation, variational…

  3. [Measuring the electricity frequency properties of blood].

    PubMed

    Huang, Hua; Hu, Maoqing; Chen, Huaiqing; Yuan, Zirun; Tong, Shan; Luo, An

    2005-04-01

    In order to understand the electricity frequency specialties of blood, we have developed a wide frequency electricity characteristic testing system and used it to test the amplitude frequency property and phase frequency property of the blood in different states and constituents at 1 Hz to 20 MHz. Further analysis on the results of tests helped us know some important properties of blood at even more microcosmic levels from a new angle. Meanwhile, some problems and considerations on the improvement of the electricity model of biotic tissue and blood were pointed out. (1) From 1 Hz to 5 KHz, the impedance of blood descended 99%. (2) Simple equivalent circuit of resistance and capacitance must be used in series equivalent but not in usual parallel connection equivalent. (3) Experiment indicated, equivalent circuits of blood need more analysis, because simple equivalent circuit of resistance and capacitance is liable to gross error. (4) When the three element model is used for measuring the resistance of inside liquid, capacitance of cell membrane and the resistance of outside liquid of blood, the three testing frequencies must be very similar.

  4. Observer-based higher order sliding mode control of power factor in three-phase AC/DC converter for hybrid electric vehicle applications

    NASA Astrophysics Data System (ADS)

    Liu, Jianxing; Laghrouche, Salah; Wack, Maxime

    2014-06-01

    In this paper, a full-bridge boost power converter topology is studied for power factor control, using output higher order sliding mode control. The AC/DC converters are used for charging the battery and super-capacitor in hybrid electric vehicles from the utility. The proposed control forces the input currents to track the desired values, which can control the output voltage while keeping the power factor close to one. Super-twisting sliding mode observer is employed to estimate the input currents and load resistance only from the measurement of output voltage. Lyapunov analysis shows the asymptotic convergence of the closed-loop system to zero. Multi-rate simulation illustrates the effectiveness and robustness of the proposed controller in the presence of measurement noise.

  5. AC Magnetic Properties of Large Volume of Water — Susceptibility Measurement in Unshielded Environment

    NASA Astrophysics Data System (ADS)

    Tsukada, Keiji; Kiwa, Toshihiko; Masuda, Yuuki

    2006-10-01

    To investigate the effect of low-frequency magnetic-field exposure of a human body, the low-frequency AC magnetic property of a large volume of water was measured by low-frequency magnetic field exposure (from 50 Hz to 1.2 kHz). The results indicate that the AC magnetic property of water is due to diamagnetism in the low-frequency range. The phase between the main magnetic field and the generated magnetic field remained constant at about 180°. Results were not affected by conductivity or pH. Moreover, the magnetic-field strength from water showed a susceptibility frequency dependence proportional to the frequency above approximately 400 Hz. Because of the incremental effects of susceptibility, the magnetic field from water was measured using a conventional magnetic sensor (magnetic resistive; MR) in an unshielded environment.

  6. Measurement of AC Losses in a Racetrack Superconducting Coil Made from YBCO Coated Conductor

    NASA Astrophysics Data System (ADS)

    Seiler, Eugen; Abrahamsen, Asger B.; Kováč, Ján; Wichmann, Mike; Træholt, Chresten

    We present the results of transport measurements of AC losses in a racetrack shaped superconducting coil made from coated conductor tape. The outer dimensions of the coil are approximately 24 cm × 12 cm and it has 57 turns. The coil is impregnated with epoxy resin and fiberglass tape is used to insulate the individual turns and to improve the mechanical properties of the epoxy when exposed to thermal cycling. The coil is manufactured as a part of the field winding of a small synchronous generator; therefore stainless steel frames are installed on the inner and outer side of the winding to reinforce it. The AC loss is measured versus the transport current Ia with the coil immersed in liquid nitrogen. Measurements at frequencies 21 Hz, 36 Hz and 72 Hz are compared. The AC losses follow Ia2 dependence at low current amplitudes and Ia3 at high amplitudes. After cutting the inner steel frame the low amplitude losses are decreased, their frequency dependence is reduced but their dependence on the current remains unchanged.

  7. AC photovoltaic module magnetic fields

    SciTech Connect

    Jennings, C.; Chang, G.J.; Reyes, A.B.; Whitaker, C.M.

    1997-12-31

    Implementation of alternating current (AC) photovoltaic (PV) modules, particularly for distributed applications such as PV rooftops and facades, may be slowed by public concern about electric and magnetic fields (EMF). This paper documents magnetic field measurements on an AC PV module, complementing EMF research on direct-current PV modules conducted by PG and E in 1993. Although not comprehensive, the PV EMF data indicate that 60 Hz magnetic fields (the EMF type of greatest public concern) from PV modules are comparable to, or significantly less than, those from household appliances. Given the present EMF research knowledge, AC PV module EMF may not merit considerable concern.

  8. Electrical penetration graphs of thrips revised: combining DC- and AC-EPG signals.

    PubMed

    Kindt, F; Joosten, N N; Tjallingii, W F

    2006-01-01

    Within thrips feeding behaviour, sequences of four waveforms have been distinguished earlier in the DC-EPG, i.e. P, Q, R and S, representing mandibular stylet insertion, maxillary stylet insertion, ingestion, and repetitive mandibular insertion, respectively. During signal analysis it appeared that transitions from one waveform to the next were difficult to establish, making results ambiguous. In order to improve the quantitative reliability of the thrips' EPG data, the DC-EPGs were recorded concurrently with AC-EPG signals, thus providing two signals from the same activities containing different information. The additional AC information did not solve most quantification problems, however. We now propose to merge waveforms P, Q, and S, into 'puncture phase' (indicated by PQ) and waveforms R, T, and U, into 'feeding phase' (indicated by R), rather than trying to analyse all separate waveforms. This will provide a more reliable and much less laborious analysis of thrips probing behaviour. Waveforms T and U are two novel waveforms identified here by combining DC- and AC-EPG recordings with concurrent video recordings. Waveform T represents a single mandibular thrust embedded in waveform R and waveform U represents the end of a probe, presumably the retraction of the maxillary stylets.

  9. Effect of nanosilica on optical, electric modulus and AC conductivity of polyvinyl alcohol/polyaniline films

    NASA Astrophysics Data System (ADS)

    El-Sayed, Somyia; Abel-Baset, Tarob; Elfadl, Azza Abou; Hassen, Arafa

    2015-05-01

    Nanosilica (NS) was synthesized by a sol-gel method and mixed with 0.98 polyvinyl alcohol (PVA)/0.02 polyaniline (PANI) in different amounts to produce nanocomposite films. High-resolution transmission electron microscopy (HR-TEM) revealed the average particle size of the NS to be ca. 15 nm. Scanning electron microscopy (SEM) showed that the NS was well-dispersed on the surface of the PVA/PNAI films. The Fourier transform infrared (FTIR) spectra of the samples showed a significant change in the intensity of the characteristic peak of the functional groups in the composite films with the amount of NS added. The absorbance and refractive index (n) of the composites were studied in the UV-vis range, and the optical energy band gap, Eg, and different optical parameters were calculated. The dielectric loss modulus, M″ and ac conductivity, σac, of the samples were studied within 300-425 K and 0.1 kHz-5 MHz, respectively. Two relaxation peaks were observed in the frequency dependence of the dielectric loss modulus, M″. The behavior of σac(f) for the composite films indicated that the conduction mechanism was correlated barrier hopping (CBH). The results of this work are discussed and compared with those of previous studies of similar composites.

  10. Frequency and voltage dependence dielectric properties, ac electrical conductivity and electric modulus profiles in Al/Co3O4-PVA/p-Si structures

    NASA Astrophysics Data System (ADS)

    Bilkan, Çiğdem; Azizian-Kalandaragh, Yashar; Altındal, Şemsettin; Shokrani-Havigh, Roya

    2016-11-01

    In this research a simple microwave-assisted method have been used for preparation of cobalt oxide nanostructures. The as-prepared sample has been investigated by UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM). On the other hand, frequency and voltage dependence of both the real and imaginary parts of dielectric constants (ε‧, ε″) and electric modulus (M‧ and M″), loss tangent (tanδ), and ac electrical conductivity (σac) values of Al/Co3O4-PVA/p-Si structures were obtained in the wide range of frequency and voltage using capacitance (C) and conductance (G/ω) data at room temperature. The values of ε‧, ε″ and tanδ were found to decrease with increasing frequency almost for each applied bias voltage, but the changes in these parameters become more effective in the depletion region at low frequencies due to the charges at surface states and their relaxation time and polarization effect. While the value of σ is almost constant at low frequency, increases almost as exponentially at high frequency which are corresponding to σdc and σac, respectively. The M‧ and M″ have low values at low frequencies region and then an increase with frequency due to short-range mobility of charge carriers. While the value of M‧ increase with increasing frequency, the value of M″ shows two peak and the peaks positions shifts to higher frequency with increasing applied voltage due to the decrease of the polarization and Nss effects with increasing frequency.

  11. Direct Detection of Pure ac Spin Current by X-Ray Pump-Probe Measurements

    NASA Astrophysics Data System (ADS)

    Li, J.; Shelford, L. R.; Shafer, P.; Tan, A.; Deng, J. X.; Keatley, P. S.; Hwang, C.; Arenholz, E.; van der Laan, G.; Hicken, R. J.; Qiu, Z. Q.

    2016-08-01

    Despite recent progress in spin-current research, the detection of spin current has mostly remained indirect. By synchronizing a microwave waveform with synchrotron x-ray pulses, we use the ferromagnetic resonance of the Py (Ni81Fe19 ) layer in a Py /Cu /Cu75Mn25/Cu /Co multilayer to pump a pure ac spin current into the Cu75Mn25 and Co layers, and then directly probe the spin current within the Cu75Mn25 layer and the spin dynamics of the Co layer by x-ray magnetic circular dichroism. This element-resolved pump-probe measurement unambiguously identifies the ac spin current in the Cu75Mn25 layer.

  12. Electrical test methods for on-line fuel cell ohmic resistance measurement

    NASA Astrophysics Data System (ADS)

    Cooper, K. R.; Smith, M.

    The principles and trade-offs of four electrical test methods suitable for on-line measurement of the ohmic resistance (R Ω) of fuel cells is presented: current interrupt, AC resistance, high frequency resistance (HFR), and electrochemical impedance spectroscopy (EIS). The internal resistance of a proton exchange membrane (PEM) fuel cell determined with the current interrupt, HFR and EIS techniques is compared. The influence of the AC amplitude and frequency of the HFR measurement on the observed ohmic resistance is examined, as is the ohmic resistance extracted from the EIS data by modeling the spectra with a transmission line model for porous electrodes. The ohmic resistance of a H 2/O 2 PEM fuel cell determined via the three methods was within 10-30% of each other. The current interrupt technique consistently produced measured cell resistances that exceeded those of the other two techniques. For the HFR technique, the frequency at which the measurement was conducted influenced the measured resistance (i.e., higher frequency providing smaller R Ω), whereas the AC amplitude did not effect the observed value. The difference in measured ohmic resistance between these techniques exceeds that reasonably accounted for by measurement error. The source of the discrepancy between current interrupt and impedance-based methods is attributed to the difference in the response of a non-uniformly polarized electrode, such as a porous electrode with non-negligible ohmic resistance, to a large perturbation (current interrupt event) as compared to a small perturbation (impedance measurement).

  13. Recent Advances in AC-DC Transfer Measurements Using Thin-Film Thermal Converters

    SciTech Connect

    WUNSCH,THOMAS F.; KINARD,JOSEPH R.; MANGINELL,RONALD P.; LIPE,THOMAS E.; SOLOMON JR.,OTIS M.; JUNGLING,KENNETH C.

    2000-12-08

    New standards for ac current and voltage measurements, thin-film multifunction thermal converters (MJTCS), have been fabricated using thin-film and micro-electro-mechanical systems (MEMS) technology. Improved sensitivity and accuracy over single-junction thermoelements and targeted performance will allow new measurement approaches in traditionally troublesome areas such as the low frequency and high current regimes. A review is presented of new microfabrication techniques and packaging methods that have resulted from a collaborative effort at Sandia National Laboratories and the National Institute of Standards and Technology (MHZ).

  14. Physics-Based Modeling of Electric Operation, Heat Transfer, and Scrap Melting in an AC Electric Arc Furnace

    NASA Astrophysics Data System (ADS)

    Opitz, Florian; Treffinger, Peter

    2016-04-01

    Electric arc furnaces (EAF) are complex industrial plants whose actual behavior depends upon numerous factors. Due to its energy intensive operation, the EAF process has always been subject to optimization efforts. For these reasons, several models have been proposed in literature to analyze and predict different modes of operation. Most of these models focused on the processes inside the vessel itself. The present paper introduces a dynamic, physics-based model of a complete EAF plant which consists of the four subsystems vessel, electric system, electrode regulation, and off-gas system. Furthermore the solid phase is not treated to be homogenous but a simple spatial discretization is employed. Hence it is possible to simulate the energy input by electric arcs and fossil fuel burners depending on the state of the melting progress. The model is implemented in object-oriented, equation-based language Modelica. The simulation results are compared to literature data.

  15. Electrical resistance tomography from measurements inside a steel cased borehole

    DOEpatents

    Daily, William D.; Schenkel, Clifford; Ramirez, Abelardo L.

    2000-01-01

    Electrical resistance tomography (ERT) produced from measurements taken inside a steel cased borehole. A tomographic inversion of electrical resistance measurements made within a steel casing was then made for the purpose of imaging the electrical resistivity distribution in the formation remotely from the borehole. The ERT method involves combining electrical resistance measurements made inside a steel casing of a borehole to determine the electrical resistivity in the formation adjacent to the borehole; and the inversion of electrical resistance measurements made from a borehole not cased with an electrically conducting casing to determine the electrical resistivity distribution remotely from a borehole. It has been demonstrated that by using these combined techniques, highly accurate current injection and voltage measurements, made at appropriate points within the casing, can be tomographically inverted to yield useful information outside the borehole casing.

  16. Novel multijunction thermal converter in planar technique for AC current, voltage, power and optical radiation measurement

    NASA Astrophysics Data System (ADS)

    Klonz, M.; Weimann, T.

    1990-05-01

    A new planar thin film design of multijunction thermocouples on a silicon chip containing a window with a SiO2-membrane for low heat conductance underneath of the thermocouples is described. It is used as the sensor for the temperature difference in a multijunction thermal converter for ac-dc transfer of electrical quantities like voltage, current and power via Joule heat in a thin film resistor. By coating the heater with an optically absorbing layer it is used as a highly sensitive radiometer transferring absorbed energy to Joule heat in the resistor. The design can easily be optimized for all different frequency applications. It offers the possibility of the mass production of transfer standards at highest level of accuracy.

  17. Dielectric properties and study of AC electrical conduction mechanisms by non-overlapping small polaron tunneling model in Bis(4-acetylanilinium) tetrachlorocuprate(II) compound

    NASA Astrophysics Data System (ADS)

    Abkari, A.; Chaabane, I.; Guidara, K.

    2016-09-01

    In the present work, the synthesis and characterization of the Bis(4-acetylanilinium) tetrachlorocuprate(II) compound are presented. The structure of this compound is analyzed by X-ray diffraction which confirms the formation of single phase and is in good agreement the literature. Indeed, the Thermo gravimetric Analysis (TGA) shows that the decomposition of the compound is observed in the range of 420-520 K. However, the differential thermal analysis (DTA) indicates the presence of a phase transition at T=363 k. Furthermore, the dielectric properties and AC conductivity were studied over a temperature range (338-413 K) and frequency range (200 Hz-5 MHz) using complex impedance spectroscopy. Dielectric measurements confirmed such thermal analyses by exhibiting the presence of an anomaly in the temperature range of 358-373 K. The complex impedance plots are analyzed by an electrical equivalent circuit consisting of resistance, constant phase element (CPE) and capacitance. The activation energy values of two distinct regions are obtained from log σT vs 1000/T plot and are found to be E=1.27 eV (T<363 K) and E=1.09 eV (363 Kac conductivity, σac, has been analyzed by Jonscher's universal power law σ(ω)=σdc+Aωs. The value of s is to be temperature-dependent, which has a tendency to increase with temperature and the non-overlapping small polaron tunneling (NSPT) model is the most applicable conduction mechanism in the title compound. Complex impedance spectra of [C8H10NO]2CuCl4 at different temperatures.

  18. Electric Field Double Probe Measurements on Satellites with Very Low Perigees

    NASA Technical Reports Server (NTRS)

    Pfaff, R. F., Jr.; Freundenreich, H.; Manzer, D.; Pankow, D.; Walsh, G.

    1999-01-01

    Measurements of DC and AC electric Fields at low altitudes (less than 150 km) in the Earth's ionosphere address a wide array of important scientific questions including Joule Heating, the closure of field aligned currents, and the deviation of E x B electron velocities from ion velocity vectors influenced by collisions. Double probes represent a well-proven technique for gathering high quality DC and AC electric field measurements for which the design of the boom system is of critical importance for the success of the experiment. In general, ionospheric DC electric field instruments that achieve accuracies of 0.1 mV/m or better, place sensors at large distances from the spacecraft body in order to extend well beyond the spacecraft wake and sheath and to achieve the large signal-to-noise ratios for DC and long wavelength measurements. Additional sets of sensors inboard of the primary, outermost sensors provide useful additional information, both for diagnostics of the plasma contact potentials, which particularly enhance the DC electric field measurements on non-spinning spacecraft, and for wavelength and phase velocity measurements that use the spaced receiver or "Interferometer" technique. Accurate attitude knowledge enables V x B contributions to be subtracted from the measured potentials, and permits the measured components to be rotated into meaningful geophysical reference frames. This presentation discusses the expected performance of electric field double probe experiments and their boom mechanisms on both spinning and non-spinning satellite platforms with very low perigees. Careful selection of probe surface materials, such as titanium nitride, for the low perigee environment, as well as thermal considerations are also discussed.

  19. Theoretical analysis of AC electric field transmission into biological tissue through frozen saline for electroporation.

    PubMed

    Xiao, Chunyan; Rubinsky, Boris

    2014-12-01

    An analytical model was used to explore the feasibility of sinusoidal electric field transmission across a frozen saline layer into biological tissue. The study is relevant to electroporation and permeabilization of the cell membrane by electric fields. The concept was analyzed for frequencies in the range of conventional electroporation frequencies and electric field intensity. Theoretical analysis for a variety of tissues show that the transmission of electroporation type electric fields through a layer of frozen saline into tissue is feasible and the behavior of this composite system depends on tissue type, frozen domain temperature, and frequency. Freezing could become a valuable method for adherence of electroporation electrodes to moving tissue surfaces, such as the heart in the treatment of atrial fibrillation or blood vessels for the treatment of restenosis.

  20. Enhanced absorption performance of carbon nanostructure based metamaterials and tuning impedance matching behavior by an external AC electric field.

    PubMed

    Gholipur, Reza; Khorshidi, Zahra; Bahari, Ali

    2017-03-27

    Metamaterials have surprisingly broadened the range of available practical applications in new devices such as shielding, microwave absorbing, and novel antenna. More researches are related to the tuning DNG frequency bands of ordered or disordered metamaterials, and far less research has focused on the importance of impedance matching behavior, and is not effort and attention in adjusting the magnitude of negative permittivity values. This is particularly important if devices deal with low amplitude signals such as radio or TV antenna. The carbon/hafnium nickel oxide (C/Hf0.9Ni0.1Oy) nanocomposites with simultaneously negative permittivity and negative permeability, excellent metamaterial performance and good impedance matching could become an efficient alternative for the ordered metamaterials in wave-transparent, microwave absorbing, and solar energy harvesting fields. In this study, we prepared C/Hf0.9Ni0.1Oy nanocomposites by solvothermal method, and we clarified how the impedance matching and double negative (DNG) behaviors of C/Hf0.9Ni0.1Oy can be tuned by an external AC electric field created by electric quadrupole system. External electric field allows for the alignment of the well-dispersed nanoparticles of carbon with long-range orientations order. We believe that this finding broadens our understanding of moderate conductive material-based random metamaterials (MCMRMs), and provides a novel strategy for replacing high loss ordered or disordered metamaterials with MCMRMs.

  1. Investigation of ac-magnetic field stimulated nanoelectroporation of magneto-electric nano-drug-carrier inside CNS cells

    PubMed Central

    Kaushik, Ajeet; Nikkhah-Moshaie, Roozbeh; Sinha, Raju; Bhardwaj, Vinay; Atluri, Venkata; Jayant, Rahul Dev; Yndart, Adriana; Kateb, Babak; Pala, Nezih; Nair, Madhavan

    2017-01-01

    In this research, we demonstrate cell uptake of magneto-electric nanoparticles (MENPs) through nanoelectroporation (NEP) using alternating current (ac)-magnetic field stimulation. Uptake of MENPs was confirmed using focused-ion-beam assisted transmission electron microscopy (FIB-TEM) and validated by a numerical simulation model. The NEP was performed in microglial (MG) brain cells, which are highly sensitive for neuro-viral infection and were selected as target for nano-neuro-therapeutics. When the ac-magnetic field optimized (60 Oe at 1 kHz), MENPs were taken up by MG cells without affecting cell health (viability > 92%). FIB-TEM analysis of porated MG cells confirmed the non-agglomerated distribution of MENPs inside the cell and no loss of their elemental and crystalline characteristics. The presented NEP method can be adopted as a part of future nanotherapeutics and nanoneurosurgery strategies where a high uptake of a nanomedicine is required for effective and timely treatment of brain diseases. PMID:28374799

  2. Optical transmission versus ac magnetization measurements for monitoring colloidal Ni nanorod rotational dynamics

    NASA Astrophysics Data System (ADS)

    Gratz, M.; Tschöpe, A.

    2017-01-01

    Ni nanorods with an average length < 250 nm and diameter < 30 nm were synthesized using the AAO template method. The magnetization and optical transmission of nanorod colloidal dispersions in alternating magnetic fields were measured and analyzed with the objective of comparing the intrinsic Brownian relaxation times obtained with the two methods. The different physical origin of the measured signal, related to different moments of the orientation distribution function, and the non-linear effects expected for the large magnetic moments of the Ni nanorods at common field amplitudes required a comprehensive modelling. The time-dependent magnetization and optical transmission in ac magnetic fields was derived by numerical solution of the Fokker-Planck equation. The simulated time-dependent magnetization and optical transmission at a given frequency and field amplitude were analyzed analogous to experimental data to determine characteristic relaxation frequencies. Empirical relationships were derived which enabled extraction of the intrinsic Brownian relaxation time from the characteristic frequencies measured in the non-linear regime. Despite large differences in the characteristic frequencies obtained from magnetization and optical transmission measurements, the retrieved intrinsic Brownian relaxation times were found to agree well. The potential of ac magnetic field-dependent optical transmission for biosensing applications was demonstrated by monitoring the adsorption of the protein gelatine on the nanorod labels.

  3. Composite rod insulators for ac power lines; Electrical performance of various designs at a coastal testing station

    SciTech Connect

    Houlgate, R.G.; Swift, D.A. )

    1990-10-01

    The electrical performance of thirty-six composite insulators - of four commercial types for each AC system level of 34.5 kV, 230 kV and 500 kV - has been determined at the CEGB insulator testing station, Brighton, England. The weathershed materials were epoxy-resin, ethylene propylene rubber and silicone rubber; half of the 230 kV insulators had no stress rings. Surface leakage current was recorded for surge levels of 25 mA, 150 mA and 500 mA; a special technique was developed to obtain the flashover statistics of the 500 kV insulators, thereby enabling performance of the composite insulator to be quantified relative to that of a string of cap and pin porcelain insulators of anti-fog design, the deterioration of the insulators was observed by making regular visual inspections. The practical consequences of the findings and the causes of the degradation are discussed.

  4. Simulation and mathematical analyses of AC electric field driven apoptosis via microtubule disintegration

    NASA Astrophysics Data System (ADS)

    Tiwari, Pawan K.

    2015-09-01

    The moderate intensity alternating current electric fields with frequencies ranging between a few tens of kilohertz and a few tens of megahertz, also known as tumor treating fields (TTFs) are utilized as a modality in the electrotherapeutic treatment of the cancer cells. The application of sub-MHz TTF on the cancer cell results in the inducement of higher electric field at the furrow between the daughter cells, and such apoptosis stimulating phenomenon is investigated through the Maxwell two-dimensional (2D) finite element simulations. A furrow distance of the order of size of the nucleus accounts for the intense electric field inducement disintegrating the microtubule via the processes of its surface disruption and tubulin dimer detachment. A simulation and mathematical analyses of the microtubule disintegration mechanism is formulated to ascertain one of the factors causing an apoptosis of the cancer cells, and consequently checking their proliferation.

  5. A new measure for the strength of electrical synapses

    PubMed Central

    Haas, Julie S.

    2015-01-01

    Electrical synapses, like chemical synapses, mediate intraneuronal communication. Electrical synapses are typically quantified by subthreshold measurements of coupling, which fall short in describing their impact on spiking activity in coupled neighbors. Here, we describe a novel measurement for electrical synapse strength that directly evaluates the effect of synaptically transmitted activity on spike timing. This method, also applicable to neurotransmitter-based synapses, communicates the considerable strength of electrical synapses. For electrical synapses measured in rodent slices of the thalamic reticular nucleus and in simple model neurons, spike timing is modulated by tens of ms by activity in a coupled neighbor. PMID:26441546

  6. Investigation of critical shear stress with simultaneous measurement of electrical impedance, capacitance and light backscattering.

    PubMed

    Lee, Byoung-Kwon; Ko, Jae-yong; Lim, Hyun-jung; Nam, Jeong-Hun; Shin, Sehyun

    2012-01-01

    Recent electrical investigation of hemorheology provided useful information on the kinetics of red blood cell (RBC) aggregation. However, because of the inconsistent results in the electrical measurements, we need to understand the electrical characteristics of RBC aggregation at various flow conditions. In the present study, AC electrical-capacitance (EC) and -impedance (EI) and light backscattering (LB) were simultaneously measured for transient shear-decreasing blood flow in a microchannel. EI, EC and LB signals of RBCs in plasma show similar time-varying curves, both yielding either a peak or a minimal point in the optimal frequency range (10~500 kHz). Critical shear stress (CSS) determined from EC showed the nearly same results as that determined from LB, with yielding hematocrits-independence and dextran-concentration dependence. However, the high concentration of fibrinogen caused electrical saturation, which resulted in different results of CSS determined from between LB and EC. These results suggest that electrical properties of RBC suspensions should be further examined to replace the optical method of measurement of RBC aggregation.

  7. Destruction of Emulsions by an AC Electric Field: Importance of Partial Merging

    NASA Astrophysics Data System (ADS)

    Thiam, Abdou Rachid; Bremond, Nicolas; Bibette, Jerome

    2010-03-01

    Electrocoalescence is basically the process of blending droplets by the application of an electric field. The approach is used in petroleum refineries for the separation of water in oil emulsions (that is, by coalescing water droplets), and more recently in biotechnology industry, for the fusion of micro reactors. In a first step, we will focus on the coalesce condition for two drops under a given electric field. Microfluidics offers a comfortable setup therefore, as we sought to span a range of initial conditions in terms of the distance between the droplets, their sizes, and also a region of the applied electric field. Thus, we could establish a stability diagram according to the initial conditions and droplets' composition, which displays three domains referred to as: coalescence, no coalescence and a third one of partial coalescence, where the droplets coalesce for a brief moment then separate right afterwards. We proceeded then by generalizing the setup to the case of a stream of droplets, and we found that the evolution of the stream can be predicted by the behaviour of the local pairs of droplets, as seen in the previous step. The main outcome of that study is the total destruction of an emulsion above a critical volume fraction for a given amplitude of electric field.

  8. Redesign of an AC Magnetic Susceptometer for Measurements in Smaller Samples

    NASA Astrophysics Data System (ADS)

    Vargas, Andres; Fukuda, Ryan; Sunny, Smitha; Ho, Pei-Chun

    2013-03-01

    A new AC magnetic susceptometer was created for the purpose of measuring the magnetic properties of smaller samples, such as nanoparticles that are currently being synthesized in our lab. The susceptometer consists of a primary coil, a secondary coil, and a sample holder. The primary coil is the outer component of the susceptometer, which provides a magnetic field when current is applied due to Ampere's Law. Inside of the primary coil lies the secondary coil, which has two oppositely wound solenoids; they are oppositely wound to reduce background signal. The sample holder lies inside of the secondary coil with the sample. All of these go inside of a beryllium copper casing for protection. We tested the susceptometer by looking for the ferromagnetic phase transition of an 11 mg Gd sample. A ~ 100 μ A AC current was applied to the primary coil, which created a magnetic field that polarized the magnetic moments in the sample. This induced a voltage on the secondary coil, which is proportional to the magnetic susceptibility. We measured the temperature dependency of the induced voltage from 10 K to 300 K. The results showed a sharp increase in the induced voltage around 293K, which agrees with the known ferromagnetic transition of Gd. Research at CSU-Fresno is supported by NSF DMR-1104544. Felipe Vargas is also supported by Undergraduate Research Grant and Faculty-Sponsored Student Research Award at CSU Fresno.

  9. Oscillating Electric Field Measures the Rotation Rate in a Native Rotary Enzyme

    PubMed Central

    Ferencz, Csilla-Maria; Petrovszki, Pál; Dér, András; Sebők-Nagy, Krisztina; Kóta, Zoltán; Páli, Tibor

    2017-01-01

    Rotary enzymes are complex, highly challenging biomolecular machines whose biochemical working mechanism involves intersubunit rotation. The true intrinsic rate of rotation of any rotary enzyme is not known in a native, unmodified state. Here we use the effect of an oscillating electric (AC) field on the biochemical activity of a rotary enzyme, the vacuolar proton-ATPase (V-ATPase), to directly measure its mean rate of rotation in its native membrane environment, without any genetic, chemical or mechanical modification of the enzyme, for the first time. The results suggest that a transmembrane AC field is able to synchronise the steps of ion-pumping in individual enzymes via a hold-and-release mechanism, which opens up the possibility of biotechnological exploitation. Our approach is likely to work for other transmembrane ion-transporting assemblies, not only rotary enzymes, to determine intrinsic in situ rates of ion pumping. PMID:28345665

  10. Direct simulation of phase delay effects on induced-charge electro-osmosis under large ac electric fields

    NASA Astrophysics Data System (ADS)

    Sugioka, Hideyuki

    2016-08-01

    The standard theory of induced-charge electro-osmosis (ICEO) often overpredicts experimental values of ICEO velocities. Using a nonsteady direct multiphysics simulation technique based on the coupled Poisson-Nernst-Planck and Stokes equations for an electrolyte around a conductive cylinder subject to an ac electric field, we find that a phase delay effect concerning an ion response provides a fundamental mechanism for electrokinetic suppression. A surprising aspect of our findings is that the phase delay effect occurs even at much lower frequencies (e.g., 50 Hz) than the generally believed charging frequency of an electric double layer (typically, 1 kHz) and it can decrease the electrokinetic velocities in one to several orders. In addition, we find that the phase delay effect may also cause a change in the electrokinetic flow directions (i.e., flow reversal) depending on the geometrical conditions. We believe that our findings move toward a more complete understanding of complex experimental nonlinear electrokinetic phenomena.

  11. Structural, magnetic, DC-AC electrical conductivities and thermo electric studies of MgCuZn Ferrites for microinductor applications.

    PubMed

    Varalaxmi, N; Sivakumar, K V

    2013-01-01

    Multilayer chip inductors (MLCIs) have been rapidly developed for electromagnetic applications. NiCuZn ferrites are the most preferred ferrite materials to produce MLCIs. MgCuZn ferrites have similar properties to those of NiCuZn ferrites. MgCuZn ferrites owing to their superior properties like low magnetostriction, environmental stability, low stress sensitivity, high resistivity and low cost can replace NiCuZn ferrites, which have a wide range of electronic applications. In view of this, a series of polycrystalline MgCuZn ferrites with generic formula MgxCu0.5Zn0.5-xFe2O4 (X=0.0 0.1, 0.2, 0.3, 0.4 and 0.5) are successfully synthesized by conventional double sintering technique. The samples were then characterized by the X-ray diffraction patterns (XRD) microstructural studies and the grain size was estimated using SEM micrographs. The sintered ferrites have been investigated in their magnetic, electrical and thermoelectric effect studies, which were carried out in the temperature range from 30 °C to 490 °C. The investigated ferrites are found to exhibit excellent properties that are suitable for the core materials in multilayer chip inductors, and the results are discussed.

  12. High power ac/dc variable R dynamic electrical load simulator

    NASA Technical Reports Server (NTRS)

    Joncas, K. P.

    1974-01-01

    A study program was undertaken to investigate various concepts and techniques for identifying and simulating both the steady-state and dynamic characteristics of electrical loads for use during integrated system test and evaluation. The development of hardware capable of providing the simulation capability is discussed. A general purpose simulator was developed with the capability of realizing a variety of models where element values were discretely variable. The different models, each corresponding to real spacecraft equipment, are set up manually for each case by suitable switching and patching. The models are capable of duplicating the dynamic and steady-state response of real loads at full power.

  13. Spectral Measurements from the Optical Emission of the A.C. Plasma Anemometer

    NASA Astrophysics Data System (ADS)

    Matlis, Eric; Marshall, Curtis; Corke, Thomas; Gogineni, Sivaram

    2015-11-01

    The optical emission properties of a new class of AC-driven flow sensors based on a glow discharge (plasma) is presented. These results extend the utility of the plasma sensor that has recently been developed for measurements in high-enthalpy flows. The plasma sensor utilizes a high frequency (1MHz) AC discharge between two electrodes as the main sensing element. The voltage drop across the discharge correlates to changes in the external flow which can be calibrated for mass-flux (ρU) or pressure depending on the design of the electrodes and orientation relative to the free-stream flow direction. Recent experiments examine the potential for spectral analysis of the optical emission of the discharge to provide additional insight to the flow field. These experiments compare the optical emission of the plasma to emission from breakdown due to an ND:YAG laser. The oxygen 777.3 nm band in particular is a focus of interest as a marker for the determination of gas density.

  14. Resistivity and AC calorimetry measurements on CeNiGe2 under pressure

    NASA Astrophysics Data System (ADS)

    Holmes, A. T.; Muramatsu, T.; Miyake, A.; Kaczorowski, D.; Bukowski, Z.; Kagayama, T.; Shimizu, K.

    2007-03-01

    We present resistivity and AC calorimetry measurements of single crystalline CeNiGe2 under high pressure and low temperature in a diamond anvil cell. CeNiGe2 is a highly anisotropic, antiferromagnetic Kondo system at ambient pressure, located close to the boundary with non-magnetic systems. It has two ordering temperatures, T=3.9 K and T=3.2 K, which are suppressed under pressure. Between 0.7 and 1.4 GPa only a single transition was identified, with TN reaching 1.9 K by 1.4 GPa. At 1.9 GPa two transitions could again be seen by AC calorimetry at 2.0 and 1.3 K, accompanied by a qualitative change in the behaviour of the resistivity. The Sommerfeld coefficient showed a maximum of 755 mJ mol-1 K-2 at 1.4 GPa, up from 448 mJ mol-1 K-2 at close to ambient pressure. The residual resistivity was found to decrease sharply above 1.4 GPa after an initial increase with pressure.

  15. AC electric field for rapid assembly of nanostructured polyaniline onto microsized gap for sensor devices.

    PubMed

    La Ferrara, Vera; Rametta, Gabriella; De Maria, Antonella

    2015-07-01

    Interconnected network of nanostructured polyaniline (PANI) is giving strong potential for enhancing device performances than bulk PANI counterparts. For nanostructured device processing, the main challenge is to get prototypes on large area by requiring precision, low cost and high rate assembly. Among processes meeting these requests, the alternate current electric fields are often used for nanostructure assembling. For the first time, we show the assembly of nanostructured PANI onto large electrode gaps (30-60 μm width) by applying alternate current electric fields, at low frequencies, to PANI particles dispersed in acetonitrile (ACN). An important advantage is the short assembly time, limited to 5-10 s, although electrode gaps are microsized. That encouraging result is due to a combination of forces, such as dielectrophoresis (DEP), induced-charge electrokinetic (ICEK) flow and alternate current electroosmotic (ACEO) flow, which speed up the assembly process when low frequencies and large electrode gaps are used. The main achievement of the present study is the development of ammonia sensors created by direct assembling of nanostructured PANI onto electrodes. Sensors exhibit high sensitivity to low gas concentrations as well as excellent reversibility at room temperature, even after storage in air.

  16. Advanced single permanent magnet axipolar ironless stator ac motor for electric passenger vehicles

    NASA Technical Reports Server (NTRS)

    Beauchamp, E. D.; Hadfield, J. R.; Wuertz, K. L.

    1983-01-01

    A program was conducted to design and develop an advanced-concept motor specifically created for propulsion of electric vehicles with increased range, reduced energy consumption, and reduced life-cycle costs in comparison with conventional systems. The motor developed is a brushless, dc, rare-earth cobalt, permanent magnet, axial air gap inductor machine that uses an ironless stator. Air cooling is inherent provided by the centrifugal-fan action of the rotor poles. An extensive design phase was conducted, which included analysis of the system performance versus the SAE J227a(D) driving cycle. A proof-of-principle model was developed and tested, and a functional model was developed and tested. Full generator-level testing was conducted on the functional model, recording electromagnetic, thermal, aerodynamic, and acoustic noise data. The machine demonstrated 20.3 kW output at 1466 rad/s and 160 dc. The novel ironless stator demonstated the capability to continuously operate at peak current. The projected system performance based on the use of a transistor inverter is 23.6 kW output power at 1466 rad/s and 83.3 percent efficiency. Design areas of concern regarding electric vehicle applications include the inherently high windage loss and rotor inertia.

  17. Evaluation of pozzolanic activity by the electric resistance measurement method

    SciTech Connect

    Tashiro, Chuichi; Ikeda, Ko . Dept. of Advanced Materials Science and Engineering); Inoue, Yoshihiro )

    1994-01-01

    Measurements of electric resistance and amount of consumption of portlandite were carried out in accelerated curing conditions by preparing pastes of Fine Ceraments, fly ash, silica fume, kaolin, acid clay, zeolite and quartz activated with portlandite. Electric resistances of reactive pozzolans showed sharp rises except that of kaolin, whereas that of inactive material, quartz, showed no sharp rise. Electric resistances are proportional to the consumptions of portlandite except for fly ashes. The electric resistance measurement method combined with portlandite consumption measurement is useful to the rapid evaluation of pozzolanic activity.

  18. Lamb-shift and electric field measurements in plasmas

    NASA Astrophysics Data System (ADS)

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

    2017-01-01

    The electric field is a quantity of particular relevance in plasma physics. Indeed, its fluctuations are responsible for different macroscopic phenomena such as anomalous transport in fusion plasmas. Answering a long-standing challenge, we offer a new method to locally and non-intrusively measure weak electric fields and their fluctuations in plasmas, by means of a beam of hydrogen ions or atoms. We present measurements of the electric field in vacuum and in a plasma where Debye shielding is measured. For the first time, we have used the Lamb-shift resonance to measure oscillating electric fields around 1 GHz and observed the strong enhancement of the Lyman-α signal. The measurement is both direct and non-intrusive. This method provides sensitivity (mV cm-1) and temporal resolution (ns) that are three orders higher compared to current diagnostics. It thus allows measuring fluctuations of the electric field at scales not previously reached experimentally.

  19. Basic concepts of induced AC voltages on pipelines

    SciTech Connect

    Kirkpatrick, E.L.

    1995-07-01

    The phenomena of induced AC on pipelines sharing common rights-of-way with overhead high-voltage electrical transmission power lines is discussed. Basic concepts and techniques for personnel safety and some pipeline protective measures are reviewed.

  20. Simple uniaxial pressure device for ac-susceptibility measurements suitable for closed cycle refrigerator system.

    PubMed

    Arumugam, S; Manivannan, N; Murugeswari, A

    2007-06-01

    A simple design of the uniaxial pressure device for the measurement of ac-susceptibility at low temperatures using closed cycle refrigerator system is presented for the first time. This device consists of disc micrometer, spring holder attachment, uniaxial pressure cell, and the ac-susceptibility coil wound on stycast bobbin. It can work under pressure till 0.5 GPa and at the temperature range of 30-300 K. The performance of the system at ambient pressure is tested and calibrated with standard paramagnetic salts [Gd(2)O(3), Er(2)O(3), and Fe(NH(4)SO(4))(2)6H(2)O], Fe(3)O(4), Gd metal, Dy metal, superconductor (YBa(2)Cu(3)O(7)), manganite (La(1.85)Ba(0.15)MnO(3)), and spin glass material (Pr(0.8)Sr(0.2)MnO(3)). The performance of the uniaxial pressure device is demonstrated by investigating the uniaxial pressure dependence of La(1.85)Ba(0.15)MnO(3) single crystal with P||c axis. The Curie temperature (T(c)) decreases as a function of pressure with P||c axis (dT(c)dP(||c axis)=-11.65 KGPa) up to 46 MPa. The design is simple, is user friendly, and does not require pressure calibration. Measurement can even be made on thin and small size oriented crystals. The failure of the coil is remote under uniaxial pressure. The present setup can be used as a multipurpose uniaxial pressure device for the measurement of Hall effect and thermoelectric power with a small modification in the pressure cell.

  1. Simple uniaxial pressure device for ac-susceptibility measurements suitable for closed cycle refrigerator system

    NASA Astrophysics Data System (ADS)

    Arumugam, S.; Manivannan, N.; Murugeswari, A.

    2007-06-01

    A simple design of the uniaxial pressure device for the measurement of ac-susceptibility at low temperatures using closed cycle refrigerator system is presented for the first time. This device consists of disc micrometer, spring holder attachment, uniaxial pressure cell, and the ac-susceptibility coil wound on stycast bobbin. It can work under pressure till 0.5GPa and at the temperature range of 30-300K. The performance of the system at ambient pressure is tested and calibrated with standard paramagnetic salts [Gd2O3, Er2O3, and Fe(NH4SO4)26H2O], Fe3O4, Gd metal, Dy metal, superconductor (YBa2Cu3O7), manganite (La1.85Ba0.15MnO3), and spin glass material (Pr0.8Sr0.2MnO3). The performance of the uniaxial pressure device is demonstrated by investigating the uniaxial pressure dependence of La1.85Ba0.15MnO3 single crystal with P ‖c axis. The Curie temperature (Tc) decreases as a function of pressure with P ‖c axis (dTc/dP‖caxis=-11.65K/GPa) up to 46MPa. The design is simple, is user friendly, and does not require pressure calibration. Measurement can even be made on thin and small size oriented crystals. The failure of the coil is remote under uniaxial pressure. The present setup can be used as a multipurpose uniaxial pressure device for the measurement of Hall effect and thermoelectric power with a small modification in the pressure cell.

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

    NASA Technical Reports Server (NTRS)

    Ruhnke, L. H. (Inventor)

    1973-01-01

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

  3. Measurement and optimization of electrical process window

    NASA Astrophysics Data System (ADS)

    Chan, Tuck-Boon; Kagalwalla, Abde Ali; Gupta, Puneet

    2010-03-01

    Process window (PW) is a collection of values of process parameters that allow circuit to be printed and to operate under desired specifications. Conventional process window which is determined through geometrical fidelity, geometric process window (GPW), does not account for lithography effects on electrical metrics such as delay and power. In contrast to GPW, this paper introduces electrical process window (EPW) which accounts for electrical specifications. Process parameters are considered within EPW if the performance (delay and leakage power) of printed circuit is within desired specifications. Our experiment results show that the area of EPW is 1.5~6x larger than that of GPW. This implies that even if a layout falls outside geometric tolerance, the electrical performance of the circuit may satisfy desired specifications. In addition to process window evaluation, we show that EPW can be enlarged by 10% on average using gate length biasing and Vth push. We also propose approximate methods to evaluate EPW, which can be used in the absence of any design information. Our results show that the proposed approximation method can estimate more than 80% of the area of reference EPW.

  4. Electrical conductivity measurements of nanofluids and development of new correlations.

    PubMed

    Konakanchi, Hanumantharao; Vajjha, Ravikanth; Misra, Debasmita; Das, Debendra

    2011-08-01

    In this study the electrical conductivity of aluminum oxide (Al2O3), silicon dioxide (SiO2) and zinc oxide (ZnO) nanoparticles dispersed in propylene glycol and water mixture were measured in the temperature range of 0 degrees C to 90 degrees C. The volumetric concentration of nanoparticles in these fluids ranged from 0 to 10% for different nanofluids. The particle sizes considered were from 20 nm to 70 nm. The electrical conductivity measuring apparatus and the measurement procedure were validated by measuring the electrical conductivity of a calibration fluid, whose properties are known accurately. The measured electrical conductivity values agreed within +/- 1% with the published data reported by the manufacturer. Following the validation, the electrical conductivities of different nanofluids were measured. The measurements showed that electrical conductivity of nanofluids increased with an increase in temperature and also with an increase in particle volumetric concentration. For the same nanofluid at a fixed volumetric concentration, the electrical conductivity was found to be higher for smaller particle sizes. From the experimental data, empirical models were developed for three nanofluids to express the electrical conductivity as functions of temperature, volumetric concentration and the size of the nanoparticles.

  5. AC Electric Field Enhances Cryopreservation Efficiency of Sprague-Dawley Rat Liver During a Slow Freezing Procedure.

    PubMed

    Ma, Ya H; Qin, Guo F; Li, Jing; Ding, Gui R; Xu, Sheng L; Zhou, Yan; Guo, Guo Z

    2016-02-01

    Slow freezing coupled with an AC electric field (ACEF) has been demonstrated to miniaturize the ice crystals of a 0.9% (w/v) NaCl solution in a prior study. The aim of this study was to assess the effect of ACEF on Sprague-Dawley (SD) rat liver in vitro during the slow cooling procedure. SD rat liver exposed to an oscillating electric field was frozen in a programmed freezer initially down to -30°C at a cooling rate of -1°C/min and continuing down to -80°C at a cooling rate of -5°C/min. The cryovials were finally transferred into liquid nitrogen for 7 days. The frequency range was 0-20 MHz, and peak field strength was 1,000 V/m. For the sham and electric-exposed groups, the freezing solution consisted of 0%, 2.5%, 5.0%, 7.5%, or 10% (v/v) dimethyl sulfoxide (DMSO) Dulbecco's modified Eagles' medium culture solution, and fresh tissue was selected as the control group. The changes in cell survival rate, adenosine triphosphate (ATP) content, and morphology of fresh and frozen-thawed liver tissue were examined. Compared with the sham group with 5.0% DMSO, the result showed that slow freezing coupled with 2.45 MHz or 5 MHz ACEF significantly increased the relative survival rate by 43.27% and 26.31% (P < 0.001), respectively. However, ACEF exposure increased the ATP content compared with the sham group. Especially in 5% and 10% DMSO with 2.45 MHz ACEF exposure, the ATP content approximated the fresh group (7.3 ± 2.7 nmol/piece), corresponding to 94.52% and 80.82%. In addition, the cellular membrane and some organelles (e.g., mitochondria) in the electric-exposed group appeared to be more intact according to the transmission electron microscopy images. The underlying mechanism might be that the ACEF affects the formation and growth of the ice crystallization, and thus inhibits cryoinjury. These results show that ACEF would provide an efficient method for cryopreservation banking with a low concentration of CPA during the slow freezing process.

  6. An AC phase measuring interferometer for measuring dn/dT of fused silica and calcium fluoride at 193 nm

    SciTech Connect

    Shagam, R.N.

    1998-09-01

    A novel method for the measurement of the change in index of refraction vs. temperature (dn/dT) of fused silica and calcium fluoride at the 193 nm wavelength has been developed in support of thermal modeling efforts for the development of 193 nm-based photolithographic exposure tools. The method, based upon grating lateral shear interferometry, uses a transmissive linear grating to divide a 193 nm laser beam into several beam paths by diffraction which propagate through separate identical material samples. One diffracted order passing through one sample overlaps the undiffracted beam from a second sample and forms interference fringes dependent upon the optical path difference between the two samples. Optical phase delay due to an index change from heating one of the samples causes the interference fringes to change sinusoidally with phase. The interferometer also makes use of AC phase measurement techniques through lateral translation of the grating. Results for several samples of fused silica and calcium fluoride are demonstrated.

  7. A novel design of DC-AC electrical machine rotary converter for hybrid solar and wind energy applications

    NASA Astrophysics Data System (ADS)

    Mohammed, K. G.; Ramli, A. Q.; Amirulddin, U. A. U.

    2013-06-01

    This paper proposes the design of a new bi-directional DC-AC rotary converter machine to convert a d.c. voltage to three-phase voltage and vice-versa using a two-stage energy conversion machine. The rotary converter consists of two main stages which are combined into single frame. These two stages are constructed from three main electromagnetic components. The first inner electromagnetic component represents the input stage that enables the DC power generated by solar energy from photo-voltaic cells to be transformed by the second and third components electro-magnetically to produce multi-phase voltages at the output stage. At the same time, extra kinetic energy from wind, which is sufficiently available, can be added to existing torque on the second electromagnetic component. Both of these input energies will add up to the final energy generated at the output terminals. Therefore, the machine will be able to convert solar and wind energies to the output terminals simultaneously. If the solar energy is low, the available wind energy will be able to provide energy to the output terminals and at the same time charges the batteries which are connected as backup system. At this moment, the machine behaves as wind turbine. The energy output from the machine benefits from two energy sources which are solar and wind. At night when the solar energy is not available and also the load is low, the wind energy is able to charge the batteries and at the same time provides output electrical power to the remaining the load. Therefore, the proposed system will have high usage of available renewable energy as compared to separated wind or solar systems. MATLAB codes are used to calculate the required dimensions, the magnetic and electrical circuits parameters to design of the new bi-directional rotary converter machine.

  8. Developing Test Apparatus and Measurements of AC Loss of High Temperature Superconductors

    DTIC Science & Technology

    2012-11-01

    superconducting wires can be very effectively reduced in proportion of the number of filaments. The oxygen annealing eliminates the residual coupling losses by...made out of YBCO superconducting wires were studied, confirming the simulation method used to calculate and predict AC loss and hysteretic effects of... oxygen annealing were tested in order to determine their effect on AC loss reduction. Results showed that the AC loss in multifilament

  9. Protein kinase C activity is altered in HL60 cells exposed to 60 Hz AC electric fields

    SciTech Connect

    Holian, O.; Reyes, H.M.; Attar, B.M.; Walter, R.J.; Astumian, R.D.; Lee, R.C.

    1996-12-31

    The authors examined the effects of electric fields (EFs) on the activity and subcellular distribution of protein kinase C (PKC) of living HL60 cells. Sixty Hertz AC sinusoidal EFs (1.5--1,000 mV/cm p-p) were applied for 1 h to cells (10{sup 7}/ml) in Teflon chambers at 37 C in the presence or absence of 2 {micro}M phorbol 12-myristate 13-acetate (PMA). PMA stimulation alone evoked intracellular translocation of PKC from the cytosolic to particulate fractions. In cells that were exposed to EFs (100--1,000 mV/cm) without PMA, a loss of PKC activity from the cytosol, but no concomitant rise in particulate PKC activity, was observed. In the presence of PMA, EFs (33--330 mV/cm) also accentuated the expected loss of PKC activity from the cytosol and augmented the rise in PKC activity in the particulate fraction. These data show that EFs alone or combined with PMA promote down-regulation of cytosolic PKC activity similar to that evoked by mitogens and tumor promoters but that it does not elicit the concomitant rise in particulate activity seen with those agents.

  10. Frequency Domain Analysis of Beat-Less Control Method for Converter-Inverter Driving Systems Applied to AC Electric Cars

    NASA Astrophysics Data System (ADS)

    Kimura, Akira

    In inverter-converter driving systems for AC electric cars, the DC input voltage of an inverter contains a ripple component with a frequency that is twice as high as the line voltage frequency, because of a single-phase converter. The ripple component of the inverter input voltage causes pulsations on torques and currents of driving motors. To decrease the pulsations, a beat-less control method, which modifies a slip frequency depending on the ripple component, is applied to the inverter control. In the present paper, the beat-less control method was analyzed in the frequency domain. In the first step of the analysis, transfer functions, which revealed the relationship among the ripple component of the inverter input voltage, the slip frequency, the motor torque pulsation and the current pulsation, were derived with a synchronous rotating model of induction motors. An analysis model of the beat-less control method was then constructed using the transfer functions. The optimal setting of the control method was obtained according to the analysis model. The transfer functions and the analysis model were verified through simulations.

  11. Successive superconducting transitions in Ta2S2C studied by electrical resistivity and nonlinear ac magnetic susceptibility

    NASA Astrophysics Data System (ADS)

    Suzuki, Masatsugu; Suzuki, Itsuko S.; Noji, Takashi; Koike, Yoji; Walter, Jürgen

    2007-05-01

    Ta2S2C compound undergoes superconducting transitions at Tcl=3.60±0.02K and Tcu=9.0±0.2K . The nature of successive superconducting transitions has been studied from electrical resistivity and linear and nonlinear ac magnetic susceptibilities. The resistivity ρ at H=0 shows a local maximum near Tcu , a kinklike behavior around Tcl , and reduces to zero at below T0=2.1K . The lnT dependence of ρ is observed at H=50kOe at low temperatures, which is due to a two-dimensional weak-localization effect. Below Tcu , a two-dimensional superconducting phase occurs in each TaC layer. The linear and nonlinear susceptibilities χ1″ , χ3' , χ5' , and χ7' as well as the difference δχ (=χFC-χZFC) between the field-cooled (FC) and zero-field-cooled (ZFC) susceptibilities start to appear below 6.0K , the onset temperature of irreversibility. A drastic growth of the in-plane superconducting coherence length below 6.0K gives rise to a three-dimensional superconducting phase below Tcl through interplanar Josephson couplings between adjacent TaC layers. The oscillatory behavior of χ3″ , χ5″ , and χ7″ below Tcl is related to the nonlinear behavior arising from the thermally activated flux flow.

  12. A Comparative Study on Pre-Standardization of Total AC Loss Measurements for Oxide-Superconducting Tapes in Japan

    NASA Astrophysics Data System (ADS)

    Funaki, Kazuo; Tanaka, Yasuzo; Osamura, Kozo

    2006-06-01

    We have been considering about standard methods to estimate total AC loss in oxide-superconducting tapes under practical electromagnetic conditions in future power devices. We adopt 4 candidates of the standard methods to measure the AC loss in superconducting wires exposed to AC transverse magnetic field and alternating transport current. We also introduce two pickup coil methods for comparative references of external magnetic field loss. The specimen is a Bi-2223 Ag-alloy-sheathed multifilamentary tape without twisting. 60-100 mm short pieces of specimen were cut from a terminal of a 50 m long specimen for 4 in 6 methods. A double-layer non-inductive coiled specimen was also prepared from the long specimen for the other 2 methods. The scattering in AC loss property among the short specimens prepared is less than 1% in the perpendicular field with the amplitude from 0.01 to 0.1 T at 10 Hz. The scattering in repeated measurements of the loss during 3 heat cycles is within 2-3%, which almost corresponds to that of the critical current in the long specimen. We processed the results measured by each method for the external field loss and total AC loss, summarized dispersion among the observed results of all methods and discussed about the candidates of the standard methods.

  13. Measuring electric fields from surface contaminants with neutral atoms

    SciTech Connect

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

    2007-06-15

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

  14. Aircraft measurement of electric field - Self-calibration

    NASA Technical Reports Server (NTRS)

    Winn, W. P.

    1993-01-01

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

  15. Non Invasive Sensors for Monitoring the Efficiency of AC Electrical Rotating Machines

    PubMed Central

    Zidat, Farid; Lecointe, Jean-Philippe; Morganti, Fabrice; Brudny, Jean-François; Jacq, Thierry; Streiff, Frédéric

    2010-01-01

    This paper presents a non invasive method for estimating the energy efficiency of induction motors used in industrial applications. This method is innovative because it is only based on the measurement of the external field emitted by the motor. The paper describes the sensors used, how they should be placed around the machine in order to decouple the external field components generated by both the air gap flux and the winding end-windings. The study emphasizes the influence of the eddy currents flowing in the yoke frame on the sensor position. A method to estimate the torque from the external field use is proposed. The measurements are transmitted by a wireless module (Zig-Bee) and they are centralized and stored on a PC computer. PMID:22163631

  16. Neural Network Analysis of Musculoskeletal Responses to Electrical AC-Stimulus

    DTIC Science & Technology

    2007-11-02

    in a more reliable diagnosis . Keywords - Physiotherapy, biomedical engineering, neural networks, physiological condition, frequency analysis method...accurately and give a correct diagnosis . However, as the FAM is a new and relatively unknown method, no reference values exist for the measurements. The...were classified into four classes (healthy, fibromyalgic, back pain, neck pain). The SOM was trained in the supervised mode, meaning that every diagnosis

  17. Species-Independent Femtosecond Localized Electric Field Measurement

    NASA Astrophysics Data System (ADS)

    Dogariu, Arthur; Goldberg, Benjamin M.; O'Byrne, Sean; Miles, Richard B.

    2017-02-01

    We present an optical measurement method using a femtosecond laser for nonintrusive measurements of electric field strength and orientation in virtually any gas or gas mixture via second-harmonic generation. This simple method takes advantage of the asymmetry in polarizability induced by an applied electric field, which enables the otherwise forbidden second-harmonic generation in any centrosymmetric or homogeneous media. The use of a femtosecond laser source permits high intensities without avalanche breakdown and leads to the measurement of electric field strength down to approximately 100 V / cm in air with submillimeter spatial resolution governed by the confocal parameter and femtosecond temporal resolution governed by the laser-pulse duration.

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

    SciTech Connect

    Hayden, Carl C.; Farrow, Roger L.

    2011-01-01

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

  19. Electric Field and Density Measurements with STEREO-SWaves.

    NASA Astrophysics Data System (ADS)

    Kellogg, P. J.; Goetz, K.; Monson, S. J.; Bale, S. D.; Maksimovic, M.

    2007-12-01

    The STEREO experiment SWaves has a low frequency part which is designed to make measurements of low frequency electric fields and rapid measurements of density fluctuations, using the three 6 meter stacer monopole antennas. The short antennas of STEREO respond both to density fluctuations and to electric fields. Therefore, it is desired to obtain four quantities, density and 3 components of electric field, from three measurements, the potentials on the three orthogonal antennas relative to the spacecraft, which requires some additional information. One possibility is to add a fourth equation implied by the large plasma conductivity, so large that electric field parallel to the magnetic field is zero, a condition which has often been used in electric field measurements. Under selected conditions, this seems to work. There are also conditions, for example ion acoustic waves, where the responses to density fluctuations and to electric fields are available from dispersion relations, and this provides another possible solution. A situation where it is not likely that the parallel electric field is zero is the case of solitary, intense bursts of Langmuir waves. For this case, it is expected that there is an electron density depression due to the ponderomotive pressure, and a resulting low frequency electric field from the non-neutrality which would be expected to have components parallel to the magnetic field. Examples will be discussed.

  20. Assembly for electrical conductivity measurements in the piston cylinder device

    DOEpatents

    Watson, Heather Christine [Dublin, CA; Roberts, Jeffrey James [Livermore, CA

    2012-06-05

    An assembly apparatus for measurement of electrical conductivity or other properties of a sample in a piston cylinder device wherein pressure and heat are applied to the sample by the piston cylinder device. The assembly apparatus includes a body, a first electrode in the body, the first electrode operatively connected to the sample, a first electrical conductor connected to the first electrode, a washer constructed of a hard conducting material, the washer surrounding the first electrical conductor in the body, a second electrode in the body, the second electrode operatively connected to the sample, and a second electrical conductor connected to the second electrode.

  1. Recent measurements of middle atmospheric electric fields and related parameters

    NASA Astrophysics Data System (ADS)

    Zadorozhny, A. M.; Tyutin, A. A.; Bragin, O. A.; Kikhtenko, V. N.

    1994-03-01

    In 1989, two series of rocket measurements were carried out to investigate middle atmosphere electric fields. The measurements were taken both in the Northern Hemisphere on Heiss Island (80 deg 37 N and 58 deg 03 min E) and in the Southern Hemisphere in the Indian Ocean (40-60 deg S and approx. 45 deg E) on board the research vessel 'Akademik Shirshov'. Along with the vertical electric fields, aerosol content and positive ion density were also measured. Some of the rocket launches were made during the extremely strong solar proton events (SPE) of October 1989. The experiments showed the strong variability of the electric fields in the middle atmosphere at polar and high middle latitudes. In all the measurements the maximum of the vertical electric field height profile in the lower mesosphere was observed to be more than approx. 1 V/m. The electric field strength and the field direction at maximum varied considerably among the launches. A maximum value of +12 V/m was detected at a height of about 58 km at 58 deg 30 mins on 21 October 1989 during the SPE. The simultaneous measurements of the electric field strength, positive ion density and aerosols point out both an ion-aerosol interaction and a connection between the mesospheric electric fields and aerosol content.

  2. Electrical derivative measurement of quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Guo, Dingkai; Cheng, Liwei; Chen, Xing; Choa, Fow-Sen; Fan, Jenyu; Worchesky, Terry

    2011-02-01

    The electrical derivative characteristics of quantum cascade lasers (QCLs) are investigated to test the QCL threshold, leakage current, and possibly explore carrier transport. QCL thresholds can be identified by searching for the slope peak of the first derivative of the I-V curves and can be further confirmed with its alignment to the peak of the second derivative of the I-V curves. Leakage current in QCLs with oxide-blocked ridge waveguides and buried heterostructure (BH) waveguides are studied and compared. The oxide-blocking structures provide the lowest leakage current although the capped-mesa-BH (CMBH) QCLs provide the toughest durability under highly stressful operations. The leakage current of CMBH QCLs are also compared at different temperatures.

  3. Non-Contact Electrical Conductivity Measurement Technique for Molten Metals

    NASA Technical Reports Server (NTRS)

    Rhim, W. K.; Ishikawa, T.

    1998-01-01

    A non-contact technique of measuring the electrical conductivity (or resistivity) of conducting liquids while they are levitated by the high temperature electrostatic levitator in a high vacuum is reported.

  4. Simultaneous measurement of nanoscale electric and magnetic optical fields

    NASA Astrophysics Data System (ADS)

    Le Feber, B.; Rotenberg, N.; Beggs, D. M.; Kuipers, L.

    2014-01-01

    Control of light-matter interactions at the nanoscale has advanced fields such as quantum optics, photovoltaics and telecommunications. These advances are driven by an improved understanding of the nanoscale behaviour of light, enabled by direct observations of the local electric fields near photonic nanostructures. With the advent of metamaterials that respond to the magnetic component of light, schemes have been developed to measure the nanoscale magnetic field. However, these structures interact not only with the magnetic field, but also with the electric field of light. Here, we demonstrate the essential simultaneous detection of both electric and magnetic fields with subwavelength resolution. By explaining our measurements through reciprocal considerations, we create a route towards designing probes sensitive to specific desired combinations of electric and magnetic field components. Simultaneous access to nanoscale electric and magnetic fields will pave the way for new designs of optical nanostructures and metamaterials.

  5. Measurements of atmospheric electrical parameters and ELF electromagnetic emissions during a meteorological balloon flight.

    NASA Astrophysics Data System (ADS)

    Benda, Robert; Dujany, Matthieu; Berthomieu, Roland; Boissier, Mathilde; Bruneel, Pierre; Fischer, Lucie; Focillon, William; Gullo, Robin; Hubert, Valentin; Lafforgue, Gaétan; Loe-Mie, Marichka; Messager, Adrien; Roy, Felix; Auvray, Gérard; Bertrand, Fabrice; Coulomb, Romain; Deprez, Gregoire; Berthelier, Jean-Jacques

    2016-04-01

    Measurements of electric field and atmospheric conductivity were performed onboard a small payload flown under a meteorological balloon during a fair weather period. This experiment is part of a project to study thunderstorms and TLE organized in the frame of the engineering cursus at Ecole Polytechnique. The payload is equipped with 4 electrodes to measure the 3 components of the DC and AC electric fields up to 3.2 kHz. Dedicated sequences of operation, when one electrode is operated in the relaxation mode, have been used to determine the positive and negative electrical conductivities. Altitude profiles of the DC vertical electric field and conductivities in agreement with expected fair weather parameters were obtained from ~ 3.5 to ~ 13 km before the failure of a battery. At an altitude of ~ 9 km slight disturbances in the electric field suggest the traversal of thin clouds with disturbed electrical characteristics. Schumann resonances were observed up to the fifth harmonics at levels that are typical of a quiet period over Europe with most thunderstorms located over remote longitudinal sectors. EM waves due the power lines at 50Hz are detected during the whole measuring period and their altitude and horizontal variations will be presented as a function of the position of the balloon over the ground power network. A surprising and interesting observation was made of a Russian transmitter at 82 Hz located in Murmansk region and used for sub-marine communications. We shall present an initial analysis of the amplitude and polarization of the corresponding signal.

  6. Microtubule alignment and manipulation using AC electrokinetics.

    PubMed

    Uppalapati, Maruti; Huang, Ying-Ming; Jackson, Thomas N; Hancock, William O

    2008-09-01

    The kinesin-microtubule system plays an important role in intracellular transport and is a model system for integrating biomotor-driven transport into microengineered devices. AC electrokinetics provides a novel tool for manipulating and organizing microtubules in solution, enabling new experimental geometries for investigating and controlling the interactions of microtubules and microtubule motors in vitro. By fabricating microelectrodes on glass substrates and generating AC electric fields across solutions of microtubules in low-ionic-strength buffers, bundles of microtubules are collected and aligned and the electrical properties of microtubules in solution are measured. The AC electric fields result in electro-osmotic flow, electrothermal flow, and dielectrophoresis of microtubules, which can be controlled by varying the solution conductivity, AC frequency, and electrode geometry. By mapping the solution conductivity and AC frequency over which positive dielectrophoresis occurs, the apparent conductivity of taxol-stabilized bovine-brain microtubules in PIPES buffer is measured to be 250 mS m(-1). By maximizing dielectrophoretic forces and minimizing electro-osmotic and electrothermal flow, microtubules are assembled into opposed asters. These experiments demonstrate that AC electrokinetics provides a powerful new tool for kinesin-driven transport applications and for investigating the role of microtubule motors in development and maintenance of the mitotic spindle.

  7. Introducing AC Inductive Reactance with a Power Tool

    ERIC Educational Resources Information Center

    Bryant, Wesley; Baker, Blane

    2016-01-01

    The concept of reactance in AC electrical circuits is often non-intuitive and difficult for students to grasp. In order to address this lack of conceptual understanding, classroom exercises compare the predicted resistance of a power tool, based on electrical specifications, to measured resistance. Once students discover that measured resistance…

  8. Simultaneous measurements of somatosensory evoked AC and near-DC MEG signals.

    PubMed

    Körber, Rainer; Curio, Gabriel; Hartwig, Stefan; Hilschenz, Ingo; Höfner, Nora; Scheer, Hans-Jürgen; Trahms, Lutz; Voigt, Jens; Burghoff, Martin

    2011-04-01

    Magnetoencephalography measurements of somatosensory evoked brain activity taken inside an extremely magnetically shielded room are reported. The massive low frequency shielding in combination with a high sampling rate enabled the simultaneous observation of AC and near-DC effects. Neuronal activation was achieved by repetitive electrostimulation of the right median nerve above motor threshold using repetition rates from 3 Hz to 12 Hz. Stimulation sequences lasted for 10 s and were interspersed with periods of rest of equal length. The recorded magnetic fields, inferred for the N20m and a sustained near-DC component, revealed mainly dipolar patterns with mutually rotated orientations with angles of rotation of 30° and 75°. At the start of the stimulation we observed a fast rise within 100 ms in the evoked magnetic near-DC fields for which a maximum equivalent current dipole strength of 65 nAm was obtained. The sustained fields decayed by a factor of ∼4 to a lower DC-level B(γ) with a time constant τ of order of seconds. For 12 Hz repetition rate B(γ) was decreased. We suggest that the sustained neuronal activity evoked by repetitive electrostimulation could provide a suitable scheme to realize the direct detection of DC effects of neuronal currents via low field magnetic resonance.

  9. Protein Aggregation Measurement through Electrical Impedance Spectroscopy

    NASA Astrophysics Data System (ADS)

    Affanni, A.; Corazza, A.; Esposito, G.; Fogolari, F.; Polano, M.

    2013-09-01

    The paper presents a novel methodology to measure the fibril formation in protein solutions. We designed a bench consisting of a sensor having interdigitated electrodes, a PDMS hermetic reservoir and an impedance meter automatically driven by calculator. The impedance data are interpolated with a lumped elements model and their change over time can provide information on the aggregation process. Encouraging results have been obtained by testing the methodology on K-casein, a protein of milk, with and without the addition of a drug inhibiting the aggregation. The amount of sample needed to perform this measurement is by far lower than the amount needed by fluorescence analysis.

  10. Electrical charge measurements on fine airborne particles

    SciTech Connect

    Tardos, G.I.; Dietz, P.W.; Snaddon, R.W.L.

    1984-11-01

    A small parallel-plate precipitator and a theoretical collection model have been used to determine the distribution of charges acquired by monodisperse airborne polystyrene latex particles in a corona charger. The mean charge based on the total number of particles was found to be slightly higher than half the predicted saturation charge, and it agreed well with independent measurements made in a Faraday cage particle separator. The importance of careful measurements of particle charge in fine particle transport studies is highlighted by a discussion of the effect of charge (particle mobility) distribution width on observed transport characteristics.

  11. Measuring the local electrical conductivity of human brain tissue

    NASA Astrophysics Data System (ADS)

    Akhtari, M.; Emin, D.; Ellingson, B. M.; Woodworth, D.; Frew, A.; Mathern, G. W.

    2016-02-01

    The electrical conductivities of freshly excised brain tissues from 24 patients were measured. The diffusion-MRI of the hydrogen nuclei of water molecules from regions that were subsequently excised was also measured. Analysis of these measurements indicates that differences between samples' conductivities are primarily due to differences of their densities of solvated sodium cations. Concomitantly, the sample-to-sample variations of their diffusion constants are relatively small. This finding suggests that non-invasive in-vivo measurements of brain tissues' local sodium-cation density can be utilized to estimate its local electrical conductivity.

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

    DOEpatents

    Lee, Ki Ha

    2002-01-01

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

  13. 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.

  14. Wet method for measuring starch gelatinization temperature using electrical conductivity.

    PubMed

    Morales-Sanchez, E; Figueroa, J D C; Gaytan-Martínez, M

    2009-09-01

    The objective of the present study was to develop a method for obtaining the gelatinization temperature of starches by using electrical conductivity. Native starches from corn, rice, potato, and wheat were prepared with different proportions of water and heated from room temperature to 90 degrees C, in a device especially designed for monitoring the electrical conductivity as a function of temperature. The results showed a linear trend of the electrical conductivity with the temperature until it reaches the onset gelatinization temperature. After that point, the electrical conductivity presented an increment or decrement depending on the water content in the sample and it was related to starch swelling and gelatinization phenomena. At the end gelatinization temperature, the conductivity becomes stable and linear, indicating that there are no more changes of phase. The starch gelatinization parameter, which was evaluated in the 4 types of starches using the electrical conductivity, was compared with those obtained by using differential scanning calorimeter (DSC). The onset temperature at which the electrical conductivity increased or decreased was found to be similar to that obtained by DSC. Also, the final temperature at which the electrical conductivity returned to linearity matched the end gelatinization temperature of the DSC. Further, a wet method for measuring the onset, peak, and end gelatinization temperatures as a function of temperature using the electrical conductivity curves is presented for a starch-water suspension.

  15. Electric field measurements during the Condor critical velocity experiment

    NASA Technical Reports Server (NTRS)

    Kelley, M. C.; Pfaff, R. F.; Haerendel, G.

    1986-01-01

    The instrumentation of the Condor critical velocity Ba experiment (Wescott et al., 1986) for the measurements of the energetic particles and the electric field associated with a Ba explosion is described. The Ba explosion created a complex electric field pulse detected in situ by a single-axis double electric-field probe on a separate spacecraft. The measurements provide evidence of several important links in the critical-velocity chain, and are consistent with two hypotheses. The first hypothesis involves the creation of large polarization electric field due to charge separation; the second hypothesis implies a polarization of the beam by currents flowing across it. The chain of physical processes inferred from the observations is in agreement with most theories for the Alfven process.

  16. Measurement of the direct C P -violating parameter AC P in the decay D+→K-π+π+

    NASA Astrophysics Data System (ADS)

    Abazov, V. M.; Abbott, B.; Acharya, B. S.; Adams, M.; Adams, T.; Agnew, J. P.; Alexeev, G. D.; Alkhazov, G.; Alton, A.; Askew, A.; Atkins, S.; Augsten, K.; Avila, C.; Badaud, F.; Bagby, L.; Baldin, B.; Bandurin, D. V.; Banerjee, S.; Barberis, E.; Baringer, P.; Bartlett, J. F.; Bassler, U.; Bazterra, V.; Bean, A.; Begalli, M.; Bellantoni, L.; Beri, S. B.; Bernardi, G.; Bernhard, R.; Bertram, I.; Besançon, M.; Beuselinck, R.; Bhat, P. C.; Bhatia, S.; Bhatnagar, V.; Blazey, G.; Blessing, S.; Bloom, K.; Boehnlein, A.; Boline, D.; Boos, E. E.; Borissov, G.; Borysova, M.; Brandt, A.; Brandt, O.; Brock, R.; Bross, A.; Brown, D.; Bu, X. B.; Buehler, M.; Buescher, V.; Bunichev, V.; Burdin, S.; Buszello, C. P.; Camacho-Pérez, E.; Casey, B. C. K.; Castilla-Valdez, H.; Caughron, S.; Chakrabarti, S.; Chan, K. M.; Chandra, A.; Chapon, E.; Chen, G.; Cho, S. W.; Choi, S.; Choudhary, B.; Cihangir, S.; Claes, D.; Clutter, J.; Cooke, M.; Cooper, W. E.; Corcoran, M.; Couderc, F.; Cousinou, M.-C.; Cutts, D.; Das, A.; Davies, G.; de Jong, S. J.; De La Cruz-Burelo, E.; Déliot, F.; Demina, R.; Denisov, D.; Denisov, S. P.; Desai, S.; Deterre, C.; DeVaughan, K.; Diehl, H. T.; Diesburg, M.; Ding, P. F.; Dominguez, A.; Dubey, A.; Dudko, L. V.; Duperrin, A.; Dutt, S.; Eads, M.; Edmunds, D.; Ellison, J.; Elvira, V. D.; Enari, Y.; Evans, H.; Evdokimov, V. N.; Fauré, A.; Feng, L.; Ferbel, T.; Fiedler, F.; Filthaut, F.; Fisher, W.; Fisk, H. E.; Fortner, M.; Fox, H.; Fuess, S.; Garbincius, P. H.; Garcia-Bellido, A.; García-González, J. A.; Gavrilov, V.; Geng, W.; Gerber, C. E.; Gershtein, Y.; Ginther, G.; Gogota, O.; Golovanov, G.; Grannis, P. D.; Greder, S.; Greenlee, H.; Grenier, G.; Gris, Ph.; Grivaz, J.-F.; Grohsjean, A.; Grünendahl, S.; Grünewald, M. W.; Guillemin, T.; Gutierrez, G.; Gutierrez, P.; Haley, J.; Han, L.; Harder, K.; Harel, A.; Hauptman, J. M.; Hays, J.; Head, T.; Hebbeker, T.; Hedin, D.; Hegab, H.; Heinson, A. P.; Heintz, U.; Hensel, C.; Heredia-De La Cruz, I.; Herner, K.; Hesketh, G.; Hildreth, M. D.; Hirosky, R.; Hoang, T.; Hobbs, J. D.; Hoeneisen, B.; Hogan, J.; Hohlfeld, M.; Holzbauer, J. L.; Howley, I.; Hubacek, Z.; Hynek, V.; Iashvili, I.; Ilchenko, Y.; Illingworth, R.; Ito, A. S.; Jabeen, S.; Jaffré, M.; Jayasinghe, A.; Jeong, M. S.; Jesik, R.; Jiang, P.; Johns, K.; Johnson, E.; Johnson, M.; Jonckheere, A.; Jonsson, P.; Joshi, J.; Jung, A. W.; Juste, A.; Kajfasz, E.; Karmanov, D.; Katsanos, I.; Kaur, M.; Kehoe, R.; Kermiche, S.; Khalatyan, N.; Khanov, A.; Kharchilava, A.; Kharzheev, Y. N.; Kiselevich, I.; Kohli, J. M.; Kozelov, A. V.; Kraus, J.; Kumar, A.; Kupco, A.; Kurča, T.; Kuzmin, V. A.; Lammers, S.; Lebrun, P.; Lee, H. S.; Lee, S. W.; Lee, W. M.; Lei, X.; Lellouch, J.; Li, D.; Li, H.; Li, L.; Li, Q. Z.; Lim, J. K.; Lincoln, D.; Linnemann, J.; Lipaev, V. V.; Lipton, R.; Liu, H.; Liu, Y.; Lobodenko, A.; Lokajicek, M.; Lopes de Sa, R.; Luna-Garcia, R.; Lyon, A. L.; Maciel, A. K. A.; Madar, R.; Magaña-Villalba, R.; Malik, S.; Malyshev, V. L.; Mansour, J.; Martínez-Ortega, J.; McCarthy, R.; McGivern, C. L.; Meijer, M. M.; Melnitchouk, A.; Menezes, D.; Mercadante, P. G.; Merkin, M.; Meyer, A.; Meyer, J.; Miconi, F.; Mondal, N. K.; Mulhearn, M.; Nagy, E.; Narain, M.; Nayyar, R.; Neal, H. A.; Negret, J. P.; Neustroev, P.; Nguyen, H. T.; Nunnemann, T.; Orduna, J.; Osman, N.; Osta, J.; Pal, A.; Parashar, N.; Parihar, V.; Park, S. K.; Partridge, R.; Parua, N.; Patwa, A.; Penning, B.; Perfilov, M.; Peters, Y.; Petridis, K.; Petrillo, G.; Pétroff, P.; Pleier, M.-A.; Podstavkov, V. M.; Popov, A. V.; Prewitt, M.; Price, D.; Prokopenko, N.; Qian, J.; Quadt, A.; Quinn, B.; Ratoff, P. N.; Razumov, I.; Ripp-Baudot, I.; Rizatdinova, F.; Rominsky, M.; Ross, A.; Royon, C.; Rubinov, P.; Ruchti, R.; Sajot, G.; Sánchez-Hernández, A.; Sanders, M. P.; Santos, A. S.; Savage, G.; Savitskyi, M.; Sawyer, L.; Scanlon, T.; Schamberger, R. D.; Scheglov, Y.; Schellman, H.; Schwanenberger, C.; Schwienhorst, R.; Sekaric, J.; Severini, H.; Shabalina, E.; Shary, V.; Shaw, S.; Shchukin, A. A.; Simak, V.; Skubic, P.; Slattery, P.; Smirnov, D.; Snow, G. R.; Snow, J.; Snyder, S.; Söldner-Rembold, S.; Sonnenschein, L.; Soustruznik, K.; Stark, J.; Stoyanova, D. A.; Strauss, M.; Suter, L.; Svoisky, P.; Titov, M.; Tokmenin, V. V.; Tsai, Y.-T.; Tsybychev, D.; Tuchming, B.; Tully, C.; Uvarov, L.; Uvarov, S.; Uzunyan, S.; Van Kooten, R.; van Leeuwen, W. M.; Varelas, N.; Varnes, E. W.; Vasilyev, I. A.; Verkheev, A. Y.; Vertogradov, L. S.; Verzocchi, M.; Vesterinen, M.; Vilanova, D.; Vokac, P.; Wahl, H. D.; Wang, M. H. L. S.; Warchol, J.; Watts, G.; Wayne, M.; Weichert, J.; Welty-Rieger, L.; Williams, M. R. J.; Wilson, G. W.; Wobisch, M.; Wood, D. R.; Wyatt, T. R.; Xie, Y.; Yamada, R.; Yang, S.; Yasuda, T.; Yatsunenko, Y. A.; Ye, W.; Ye, Z.; Yin, H.; Yip, K.; Youn, S. W.; Yu, J. M.; Zennamo, J.; Zhao, T. G.; Zhou, B.; Zhu, J.; Zielinski, M.; Zieminska, D.; Zivkovic, L.; D0 Collaboration

    2014-12-01

    We measure the direct C P -violating parameter AC P for the decay of the charged charm meson, D+→K-π+π+ (and charge conjugate), using the full 10.4 fb-1 sample of p p ¯ collisions at √{s }=1.96 TeV collected by the D0 detector at the Fermilab Tevatron collider. We extract the raw reconstructed charge asymmetry by fitting the invariant mass distributions for the sum and difference of charge-specific samples. This quantity is then corrected for detector-related asymmetries using data-driven methods and for possible physics asymmetries (from B →D processes) using input from Monte Carlo simulation. We measure AC P=[-0.16 ±0.15 (stat)±0.09 (syst)]% , which is consistent with zero, as expected from the standard model prediction of C P conservation, and is the most precise measurement of this quantity to date.

  17. Measuring Helical FCG Voltage with an Electric Field Antenna

    SciTech Connect

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

    2011-08-01

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

  18. Electro-optic probe measurements of electric fields in plasmas.

    PubMed

    Nishiura, M; Yoshida, Z; Mushiake, T; Kawazura, Y; Osawa, R; Fujinami, K; Yano, Y; Saitoh, H; Yamasaki, M; Kashyap, A; Takahashi, N; Nakatsuka, M; Fukuyama, A

    2017-02-01

    The direct measurements of high-frequency electric fields in a plasma bring about significant advances in the physics and engineering of various waves. We have developed an electro-optic sensor system based on the Pockels effect. Since the signal is transmitted through an optical fiber, the system has high tolerance for electromagnetic noises. To demonstrate its applicability to plasma experiments, we report the first result of measurement of the ion-cyclotron wave excited in the RT-1 magnetosphere device. This study compares the results of experimental field measurements with simulation results of electric fields in plasmas.

  19. Electro-optic probe measurements of electric fields in plasmas

    NASA Astrophysics Data System (ADS)

    Nishiura, M.; Yoshida, Z.; Mushiake, T.; Kawazura, Y.; Osawa, R.; Fujinami, K.; Yano, Y.; Saitoh, H.; Yamasaki, M.; Kashyap, A.; Takahashi, N.; Nakatsuka, M.; Fukuyama, A.

    2017-02-01

    The direct measurements of high-frequency electric fields in a plasma bring about significant advances in the physics and engineering of various waves. We have developed an electro-optic sensor system based on the Pockels effect. Since the signal is transmitted through an optical fiber, the system has high tolerance for electromagnetic noises. To demonstrate its applicability to plasma experiments, we report the first result of measurement of the ion-cyclotron wave excited in the RT-1 magnetosphere device. This study compares the results of experimental field measurements with simulation results of electric fields in plasmas.

  20. Measurement of electrical resistance after nerve injuries of the hand.

    PubMed

    Egyed, B; Eory, A; Veres, T; Manninger, J

    1980-10-01

    The authors measured electrical resistance of skin to define the sensory loss. A significant increase of the skin resistance was observed in the zone of sensory loss, as compared with the skin surfaces of normal innervation. The sensory map, sweating map (ninhydrine test) and the skin resistance map were also compared by the authors. The main advantages of the electrical skin resistance test are that it is a quantitative one, and takes less time than the other methods.

  1. Detailed electrical measurements on sago starch biopolymer solid electrolyte

    NASA Astrophysics Data System (ADS)

    Singh, Rahul; Baghel, Jaya; Shukla, S.; Bhattacharya, B.; Rhee, Hee-Woo; Singh, Pramod K.

    2014-12-01

    The biopolymer solid electrolyte has been synthesized and characterized. Potassium iodide (KI) has been added in polymer matrix to develop solid polymer electrolyte. Relationships between electrical, ionic transport parameter and mechanism have been studied in detail. Impedance spectroscopy reveals the detailed electrical studies and ion transport mechanism. The ion dissociation factor is compared with a measured dielectric constant at a fixed frequency. The dielectric data are calculated which support the ionic conductivity data.

  2. Magnetic resonance electrical impedance tomography for measuring electrical conductivity during electroporation.

    PubMed

    Kranjc, M; Bajd, F; Serša, I; Miklavčič, D

    2014-06-01

    The electroporation effect on tissue can be assessed by measurement of electrical properties of the tissue undergoing electroporation. The most prominent techniques for measuring electrical properties of electroporated tissues have been voltage-current measurement of applied pulses and electrical impedance tomography (EIT). However, the electrical conductivity of tissue assessed by means of voltage-current measurement was lacking in information on tissue heterogeneity, while EIT requires numerous additional electrodes and produces results with low spatial resolution and high noise. Magnetic resonance EIT (MREIT) is similar to EIT, as it is also used for reconstruction of conductivity images, though voltage and current measurements are not limited to the boundaries in MREIT, hence it yields conductivity images with better spatial resolution. The aim of this study was to investigate and demonstrate the feasibility of the MREIT technique for assessment of conductivity images of tissues undergoing electroporation. Two objects were investigated: agar phantoms and ex vivo liver tissue. As expected, no significant change of electrical conductivity was detected in agar phantoms exposed to pulses of all used amplitudes, while a considerable increase of conductivity was measured in liver tissue exposed to pulses of different amplitudes.

  3. ELECTRICAL AEROSOL DETECTOR (EAD) MEASUREMENTS AT THE ST. LOUIS SUPERSITE

    EPA Science Inventory

    The Model 3070A Electrical Aerosol Detector (EAD) measures a unique aerosol parameter called total aerosol length. Reported as mm/cm3, aerosol length can be thought of as a number concentration times average diameter, or simply as d1 weighting. This measurement falls between nu...

  4. Damage Diagnosis in Semiconductive Materials Using Electrical Impedance Measurements

    NASA Technical Reports Server (NTRS)

    Ross, Richard W.; Hinton, Yolanda L.

    2008-01-01

    Recent aerospace industry trends have resulted in an increased demand for real-time, effective techniques for in-flight structural health monitoring. A promising technique for damage diagnosis uses electrical impedance measurements of semiconductive materials. By applying a small electrical current into a material specimen and measuring the corresponding voltages at various locations on the specimen, changes in the electrical characteristics due to the presence of damage can be assessed. An artificial neural network uses these changes in electrical properties to provide an inverse solution that estimates the location and magnitude of the damage. The advantage of the electrical impedance method over other damage diagnosis techniques is that it uses the material as the sensor. Simple voltage measurements can be used instead of discrete sensors, resulting in a reduction in weight and system complexity. This research effort extends previous work by employing finite element method models to improve accuracy of complex models with anisotropic conductivities and by enhancing the computational efficiency of the inverse techniques. The paper demonstrates a proof of concept of a damage diagnosis approach using electrical impedance methods and a neural network as an effective tool for in-flight diagnosis of structural damage to aircraft components.

  5. Guide to Flow Measurement for Electric Propulsion Systems

    NASA Technical Reports Server (NTRS)

    Frieman, Jason D.; Walker, Mitchell L. R.; Snyder, Steve

    2013-01-01

    In electric propulsion (EP) systems, accurate measurement of the propellant mass flow rate of gas or liquid to the thruster and external cathode is a key input in the calculation of thruster efficiency and specific impulse. Although such measurements are often achieved with commercial mass flow controllers and meters integrated into propellant feed systems, the variability in potential propellant options and flow requirements amongst the spectrum of EP power regimes and devices complicates meter selection, integration, and operation. At the direction of the Committee on Standards for Electric Propulsion Testing, a guide was jointly developed by members of the electric propulsion community to establish a unified document that contains the working principles, methods of implementation and analysis, and calibration techniques and recommendations on the use of mass flow meters in laboratory and spacecraft electric propulsion systems. The guide is applicable to EP devices of all types and power levels ranging from microthrusters to high-power ion engines and Hall effect thrusters. The establishment of a community standard on mass flow metering will help ensure the selection of the proper meter for each application. It will also improve the quality of system performance estimates by providing comprehensive information on the physical phenomena and systematic errors that must be accounted for during the analysis of flow measurement data. This paper will outline the standard methods and recommended practices described in the guide titled "Flow Measurement for Electric Propulsion Systems."

  6. A two-dimensional measuring equipment for electrical steel

    SciTech Connect

    Salz, W. . Inst. fuer Werkstoffe der Elektrotechnik)

    1994-05-01

    The technical aspects of two-dimensional measuring equipment for electrical steel are described. The choice of the appropriate field sensors and the important point of the control of [rvec B](t) are described. The equipment described is designed to measure the two-dimensional properties of square shaped single sheets of all qualities of electrical steel covering the technical frequencies and induction ranges of the major applications. The equipment is useful for the manufacturers of electrical steel to control the texture of their material and for designers of machines to know about the properties of the material under two-dimensional excitation, which in case of rotational flux conditions are different from the one-dimensional properties measured with Epstein frame or single sheet testers.

  7. Contactless electrical conductivity measurement of electromagnetically levitated metallic melts

    SciTech Connect

    Richardsen, T.; Lohoefer, G.

    1999-07-01

    The electrical conductivity {sigma} of metallic liquids is of obvious importance to many liquid metal processing operations, because it controls the melt flow under the influence of electromagnetic fields, e.g. during casting processes, or in crystal growth furnaces. A facility for noninvasive measurements of the electrical conductivity of liquid metals above and below the melting temperature is presented. It combines the containerless positioning method of electromagnetic levitation with the contactless technique of inductive conductivity measurement. Contrary to the conventional measurement method, the sample is freely suspended within the measuring field and, thus, has no exactly predefined shape. This made a new theoretical basis necessary with implications on the measurement and levitation fields. Furthermore, the problem of the mutual inductive interactions between the levitation and the measuring coils had to be solved.

  8. Measurement of Electrical Conductivity for a Biomass Fire

    PubMed Central

    Mphale, Kgakgamatso; Heron, Mal

    2008-01-01

    A controlled fire burner was constructed where various natural vegetation species could be used as fuel. The burner was equipped with thermocouples to measure fuel surface temperature and used as a cavity for microwaves with a laboratory quality 2-port vector network analyzer to determine electrical conductivity from S-parameters. Electrical conductivity for vegetation material flames is important for numerical prediction of flashover in high voltage power transmission faults research. Vegetation fires that burn under high voltage transmission lines reduce flashover voltage by increasing air electrical conductivity and temperature. Analyzer determined electrical conductivity ranged from 0.0058 - 0.0079 mho/m for a fire with a maximum temperature of 1240 K. PMID:19325812

  9. Convenient mounting method for electrical measurements of thin samples

    NASA Technical Reports Server (NTRS)

    Matus, L. G.; Summers, R. L.

    1986-01-01

    A method for mounting thin samples for electrical measurements is described. The technique is based on a vacuum chuck concept in which the vacuum chuck simultaneously holds the sample and established electrical contact. The mounting plate is composed of a glass-ceramic insulating material and the surfaces of the plate and vacuum chuck are polished. The operation of the vacuum chuck is examined. The contacts on the sample and mounting plate, which are sputter-deposited through metal masks, are analyzed. The mounting method was utilized for van der Pauw measurements.

  10. Electric field measurements in a kHz-driven He jet—the influence of the gas flow speed

    NASA Astrophysics Data System (ADS)

    Sobota, A.; Guaitella, O.; Sretenović, G. B.; Krstić, I. B.; Kovačević, V. V.; Obrusník, A.; Nguyen, Y. N.; Zajíčková, L.; Obradović, B. M.; Kuraica, M. M.

    2016-12-01

    This report focuses on the dependence of electric field strength in the effluent of a vertically downwards-operated plasma jet freely expanding into room air as a function of the gas flow speed. A 30 kHz AC-driven He jet was used in a coaxial geometry, with an amplitude of 2 kV and gas flow between 700 sccm and 2000 SCCM. The electric field was measured by means of Stark polarization spectroscopy of the He line at 492.19 nm. While the minimum and the maximum measured electric fields remained unchanged, the effect of the gas flow speed is to cause stretching of the measured profile in space—the higher the flow, the longer and less steep the electric field profile. The portion of the effluent in which the electric field was measured showed an increase of electric field with increasing distance from the capillary, for which the probable cause is the contraction of the plasma bullet as it travels through space away from the capillary. There are strong indications that the stretching of the electric field profile with increase in the flow speed is caused by differences in gas mixing as a function of the gas flow speed. The simulated gas composition shows that the amount of air entrained into the gas flow behaves in a similar way to the observed behaviour of the electric field. In addition we have shown that the visible length of the plasma plume is associated with a 0.027 molar fraction of air in the He flow in this configuration, while the maximum electric field measured was associated with a 0.014 molar fraction of air at gas flow rates up to 1500 SCCM (4.9 m s-1). At higher flows vortices occur in the effluent of the jet, as seen in Schlieren visualization of the gas flow with and without the discharge.

  11. Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation.

    PubMed

    Huang, Yu; Liu, Anli A; Lafon, Belen; Friedman, Daniel; Dayan, Michael; Wang, Xiuyuan; Bikson, Marom; Doyle, Werner K; Devinsky, Orrin; Parra, Lucas C

    2017-02-07

    Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimate electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.4 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r=0.89) and depth (r=0.84) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials.

  12. Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

    PubMed Central

    Huang, Yu; Liu, Anli A; Lafon, Belen; Friedman, Daniel; Dayan, Michael; Wang, Xiuyuan; Bikson, Marom; Doyle, Werner K; Devinsky, Orrin; Parra, Lucas C

    2017-01-01

    Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.4 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.89) and depth (r = 0.84) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials. DOI: http://dx.doi.org/10.7554/eLife.18834.001 PMID:28169833

  13. Ion trap electric field measurements using slab coupled optical sensors

    NASA Astrophysics Data System (ADS)

    Shumway, L.; Chadderdon, S.; Powell, A.; Li, A.; Austin, D.; Hawkins, A.; Selfridge, R.; Schultz, S.

    2014-03-01

    Ion traps are widely used in the field of mass spectrometry. These devices use high electric fields to mass-selectively trap, eject, and count the particles of a material, producing a mass spectrum of the given material. Because of their usefulness, technology pushes for smaller, more portable ion traps for field use. Making internal ion trap field measurements not yet feasible because current electric field sensors are often too bulky or their metallic composition perturbs field measurements. Using slab coupled optical sensor (SCOS) technology, we are able to build sensors that are compatible with the spacing constraints of the ion trap. These sensors are created by attaching a nonlinear crystal slab waveguide to an optical fiber. When a laser propagates through the fiber, certain wavelengths of light couple out of the fiber via the crystal and create "resonances" in the output light spectrum. These resonances shift in proportion to a given applied electric field, and by measuring that shift, we can approximate the electric field. Developing a sensor that can effectively characterize the electric fields within an ion trap will greatly assist in ion trap design, fabrication, and troubleshooting techniques.

  14. 10 CFR 500.3 - Electric regions-electric region groupings for reliability measurements under the Powerplant and...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 4 2010-01-01 2010-01-01 false Electric regions-electric region groupings for reliability measurements under the Powerplant and Industrial Fuel Use Act of 1978. 500.3 Section 500.3 Energy DEPARTMENT OF ENERGY (CONTINUED) ALTERNATE FUELS DEFINITIONS § 500.3 Electric regions—electric region groupings...

  15. Electrical resistivity borehole measurements: application to an urban tunnel site

    NASA Astrophysics Data System (ADS)

    Denis, A.; Marache, A.; Obellianne, T.; Breysse, D.

    2002-06-01

    This paper shows how it is possible to use wells drilled during geotechnical pre-investigation of a tunneling site to obtain a 2-D image of the resistivity close to a tunnel boring machine. An experimental apparatus is presented which makes it possible to perform single and borehole-to-borehole electrical measurements independent of the geological and hydrogeological context, which can be activated at any moment during the building of the tunnel. This apparatus is first demonstrated through its use on a test site. Numerical simulations and data inversion are used to analyse the experimental results. Finally, electrical resistivity tomography and single-borehole measurements on a tunneling site are presented. Experimental results show the viability of the apparatus and the efficiency of the inverse algorithm, and also highlight the limitations of the electrical resistivity tomography as a tool for geotechnical investigation in urban areas.

  16. Electric System-wide Measurements: North American Directions

    SciTech Connect

    Widergren, Steven E.; Huang, Zhenyu; Dagle, Jeffery E.

    2007-01-03

    The western interconnected electric system of North America pioneered the concept of system-wide measurements, particularly applied to system dynamic issues. This involved the development and deployment of synchronized, sub-second measurement units and their associated data collection networks. More recently, the United States Department of Energy has collaborated with the North American Electric Reliability Council, electric utilities, reliability coordinators, equipment and software suppliers, and researchers to advance the use phasors in the eastern interconnection of North America. This paper provides an overview of the status of system-wide monitoring in North America, the directions emerging for application of this data to situational awareness and system operations, as well as the institutional changes underway to organize the relevant parties and establish a viable infrastructure to support the information exchange required to fulfill each party’s role.

  17. Chatanika radar measurements of the electrical properties of auroral arcs

    NASA Astrophysics Data System (ADS)

    Vondrak, R. R.

    Ionospheric parameters measured in the presence of auroral arcs by the incoherent scatter Chatanika radar are used to define properties of the arcs. The radar broadcasts at 3-5 MW with a range resolution of 4.5 km along the radar line-of-sight, and has yielded auroral measurements on the variation of electron density, Hall and Pederson conductivity, horizontal electric fields, electrojet currents, precipitating electron energy flux, and the Joule heating rate. Elevation-scan techniques have been utilized to study the latitude and altitude variation of the ionospheric plasma parameters, and fixed-position scans allow determination of ionization conditions, including the electric fields and the acceleration of precipitating auroral electrons. Arcs in the diffuse aurora have been found to be local conductivity enhancements, while discrete arcs correspond to the boundary plasma sheet and have an asymmetric electric field pattern reduced on the northward side.

  18. Peculiarities of electric field measurements in magnetotelluric sounding.

    NASA Astrophysics Data System (ADS)

    Pronenko, Vira; Prystai, Andrii; Korepanov, Valery

    2014-05-01

    The study of deep structure of the Earth is of great interest for both applied (e. g., mineral exploration) and scientific research. For this the electromagnetic (EM) studies which enable to construct the distribution of electrical conductivity in the Earth's crust are of great use. The most common method of EM exploration is magnetotelluric sounding (MTS). This method is a passive method of research, which uses a wide range of natural geomagnetic variations as a powerful source of electromagnetic induction in the Earth. MTS technique includes first the measurements of variations of natural electric and magnetic fields in orthogonal directions at the surface of the Earth, and then the conductivity structure of the Earth's crust is determined by the obtained data processing and as a result the geoelectric cross-section for the depths of several tens of meters to several hundred kilometres is constructed. Like other methods, MTS has its limitations. The mmeasurements of electric field are the most complicated metrological process mostly limiting the accuracy of magnetotelluric prospecting. We believe that the increase of the accuracy of the electric field measurement can significantly improve the quality of magnetotelluric data. It is known that the measurement of the electric field is the biggest problem during the MTS. First of all, this is due to quite small values of the measured variations of the electric field compared to the so-called contact potential arising at the interface of the contact of the electrode with the environment. The shortcomings of a construction of different kind of non-polarized electrode were studied and in the result a new improved design of non-polarized LEMI-701 electrode based on the combination of Cu - CuSO4 is proposed. A number of specific requirements should be taken into account at electric field meter design because it must measure signals with periods ranging from fractions of seconds to about 100.000 second with minimal error

  19. Influence of relative humidity on analyzing electric field exposure using ELF electric field measurements.

    PubMed

    Korpinen, Leena H; Kuisti, Harri A; Tarao, Hiroo; Elovaara, Jarmo A

    2013-07-01

    The objective of the study was to investigate the influence of humidity on analyzing electric field exposure using extremely low frequency (ELF) electric field measurements. The study included 322 measurements in a climate room. We used two commercial three-axis meters, EFA-3 and EFA-300, and employed two measurement techniques in the climate room where we varied the temperature from 15 to 25 °C, the relative humidity from 55% to 95%, and the electric field from 1 to 25 kV/m. We calculated Pearson correlations between humidity and percentage errors for all data and for data at different levels of humidity. When the relative humidity was below 70%, the results obtained by the different measurement methods in terms of percentage errors were of the same order of magnitude for the considered temperatures and field strength, but the results were less reliable when the relative humidity was higher than 80%. In the future, it is important to take humidity into account when electric field measurement results will be compared to the values given in different exposure guidelines.

  20. Measured electric field intensities near electric cloud discharges detected by the Kennedy Space Center's Lightning Detection and Ranging System, LDAR

    NASA Technical Reports Server (NTRS)

    Poehler, H. A.

    1977-01-01

    For a summer thunderstorm, for which simultaneous, airborne electric field measurements and Lightning Detection and Ranging (LDAR) System data was available, measurements were coordinated to present a picture of the electric field intensity near cloud electrical discharges detected by the LDAR System. Radar precipitation echos from NOAA's 10 cm weather radar and measured airborne electric field intensities were superimposed on LDAR PPI plots to present a coordinated data picture of thunderstorm activity.

  1. Measurements of middle-atmosphere electric fields and associated electrical conductivities

    NASA Technical Reports Server (NTRS)

    Hale, L. C.; Croskey, C. L.; Mitchell, J. D.

    1981-01-01

    A simple antenna for measuring the vertical electric field in the 'middle atmosphere' has been flown on a number of rocket-launched parachute-borne payloads. The data from the first nine such flights, launched under a variety of geophysical conditions, are presented, along with electrical conductivities measured simultaneously. The data include indications of layered peaks of several volts per meter in the mesospheric field at high and low latitudes in situations of relatively low conductivity. During an auroral 'REP' event the electric field reversed direction in the lower stratosphere, accompanied by a substantial enhancement in conductivity. The data generally do not confirm speculations based only on the extension of the thunderstorm circuit from below or the mapping of ionospheric and magnetospheric fields from above, but seem to require, in addition, internal generation processes in the middle atmosphere.

  2. Measuring the Electron Electric Dipole Moment Using Ytterbium Fluoride Molecules

    NASA Astrophysics Data System (ADS)

    Smallman, I. J.; Devlin, J. A.; Kara, D. M.; Hudson, J. J.; Sauer, B. E.; Tarbutt, M. R.; Hinds, E. A.

    2013-06-01

    It is well known that the existence of an electron electric dipole moment (eEDM) would violate time reversal symmetry. The Standard Model predicts an eEDM less than 10^{-38}e.cm, however many popular extensions predict values in the range 10^{-29}-10^{-24}e.cm. Our experiment currently has the potential to measure eEDMs down to approximately 10^{-29}e.cm, making it a precise probe for T-violation and physics beyond the Standard Model. We measure the eEDM by performing a type of separated oscillating field interferometry on a pulsed beam of YbF. The molecules are prepared such that the molecular spin is oriented perpendicular to an applied strong (10kV/cm) electric field. The spin is then allowed to precess about the electric field axis over a 0.5ms interaction period. We measure this angle of rotation, which is directly proportional to the eEDM. In order to measure the eEDM precisely and without error we use a complex switching technique wherein certain parameters, including the applied electric and magnetic fields, are reversed between individual molecular pulses. I will present our current technique and our most recent world leading result.

  3. Laser Measurements of Transient High-Strength Electric Fields

    DTIC Science & Technology

    1987-07-15

    Measurements of Electric Field Strength," Poster Session of Applied Spectroscopy (Miami Valley Section), University of Dayton, January 11, 1985. 2...Buswell, A. T., "Quantum Perturbation Theory of Stark- Induced Polarizability," Poster Session of Applied Spectroscopy (Miami Valley Section), University...34Theoretical Calculations of Stark- Induced Polarizabilities," Poster Session of Applied Spectroscopy (Miami Valley Section), The Ohio State University

  4. Contactless electrical conductivity measurement of metallic submicron-grain material: Application to the study of aluminum with severe plastic deformation.

    PubMed

    Mito, M; Matsui, H; Yoshida, T; Anami, T; Tsuruta, K; Deguchi, H; Iwamoto, T; Terada, D; Miyajima, Y; Tsuji, N

    2016-05-01

    We measured the electrical conductivity σ of aluminum specimen consisting of submicron-grains by observing the AC magnetic susceptibility resulting from the eddy current. By using a commercial platform for magnetic measurement, contactless measurement of the relative electrical conductivity σn of a nonmagnetic metal is possible over a wide temperature (T) range. By referring to σ at room temperature, obtained by the four-terminal method, σn(T) was transformed into σ(T). This approach is useful for cylinder specimens, in which the estimation of the radius and/or volume is difficult. An experiment in which aluminum underwent accumulative roll bonding, which is a severe plastic deformation process, validated this method of evaluating σ as a function of the fraction of high-angle grain boundaries.

  5. Elasto-electric coupling for direct electric field distribution measurement in semiconductor structures

    NASA Astrophysics Data System (ADS)

    Salamé, Basil; Holé, Stéphane

    2016-11-01

    Semiconductor materials are widely used in electronic industry, but their electrical characterization remains complex to estimate without a good model. It has already been shown that an elasto-electric coupling can be used to directly and non-destructively probe the electrical properties at the external interfaces of semi-conductor structures. In this paper, it is shown that such a coupling can also be used to probe the inner interfaces of semi-conductor structures. This capability is demonstrated by using a specific semi-conductor structure including a buried silicon p-n junction 720 μm away from the external electrodes. The signal generated by the elasto-electric coupling clearly shows separately the electric field at the electrodes and at the buried junction. The contact potential at the buried junction estimated from the measurements is in accordance with the semiconductor doping. This makes it possible to use an elasto-electric coupling for the complete characterization of semiconductor structures.

  6. New measurement of exotic decay of 225Ac by 14C emission

    NASA Astrophysics Data System (ADS)

    Guglielmetti, A.; Bonetti, R.; Ardisson, G.; Barci, V.; Giles, T.; Hussonnois, M.; Le Du, J. F.; Le Naour, C.; Mikheev, V. L.; Pasinetti, A. L.; Ravn, H. L.; Tretyakova, S. P.; Trubert, D.

    The branching ratio of 225Ac decay by emission of 14C was remeasured under improved experimental conditions by using a radioactive source produced at the ISOLDE mass-separator at CERN and a nuclear track detector technique. The result, B = λ14C/λα = (4.5+/-1.4)10-12, is consistent with the anomalously high value obtained in the 1993 experiment, thus confirming the importance of nuclear-structure effects in this exotic decay.

  7. Atmospheric Electric Field Measurements at 100 Hz and High Frequency Electric Phenomena

    NASA Astrophysics Data System (ADS)

    Conceição, Ricardo; Gonçalves da Silva, Hugo; Matthews, James; Bennett, Alec; Chubb, John

    2016-04-01

    Spectral response of Atmospheric Electric Potential Gradient (PG), symmetric to the Atmospheric Electric Field, gives important information about phenomena affecting these measurements with characteristic time-scales that appear in the spectra as specific periodicities. This is the case of urban pollution that has a clear weekly dependence and reveals itself on PG measurements by a ~7 day periodicity (Silva et al., 2014). While long-term time-scales (low frequencies) have been exhaustively explored in literature, short-term time-scales (high frequencies), above 1 Hz, have comparatively received much less attention (Anisimov et al., 1999). This is mainly because of the technical difficulties related with the storage of such a huge amount of data (for 100 Hz sampling two days of data uses a ~1 Gb file) and the response degradation of the field-meters at such frequencies. Nevertheless, important Electric Phenomena occurs for frequencies above 1 Hz that are worth pursuing, e.g. the Schumann Resonances have a signature of worldwide thunderstorm activity at frequencies that go from ~8 up to ~40 Hz. To that end the present work shows preliminary results on PG measurements at 100 Hz that took place on two clear-sky days (17th and 18th June 2015) on the South of Portugal, Évora (38.50° N, 7.91° W). The field-mill used is a JCI 131F installed in the University of Évora campus (at 2 m height) with a few trees and two buildings in its surroundings (~50 m away). This device was developed by John Chubb (Chubb, 2014) and manufactured by Chilworth (UK). It was calibrated in December 2013 and recent work by the author (who is honored in this study for his overwhelming contribution to atmospheric electricity) reveals basically a flat spectral response of the device up to frequencies of 100 Hz (Chubb, 2015). This makes this device suitable for the study of High Frequency Electric Phenomena. Anisimov, S.V., et al. (1999). On the generation and evolution of aeroelectric structures

  8. Improved monitoring of subsurface CO2 storage using novel electrical and seismic measurements: scaled laboratory studies

    NASA Astrophysics Data System (ADS)

    Ghose, R.; Kirichek, A.; Draganov, D.; Heller, K.

    2013-05-01

    For monitoring CO2 stored in appropriate geological settings like depleted oil or gas reservoirs, deep saline aquifers and deep unminable coalbeds, geophysical methods e.g., seismic, electromagnetics, gravity, and surface deformation studies serve as remote sensing techniques which generally provide a large coverage but a low spatial resolution. It has been concluded that of the various approaches, seismic methods have the broadest applicability for stored CO2 monitoring in various geologic settings. As a result, advanced and dedicated seismic monitoring techniques have been developed. However, three major issues that remain unresolved are: 1) to remove accurately the effect of the overburden layers in order to capture the change in seismic properties in the reservoir and thereby obtain reliable estimates of temporal and spatial changes of the rock-physical properties like pressure and saturation, 2) the difficulty to minimize the source-related variation in time-lapse seismic, and 3) the inability to monitor the changes in phase (supercritical, liquid or gaseous) of the stored CO2 in time and space. In order to address these crucial issues, we have concentrated on scaled laboratory tests mimicking realistic storage conditions, and have tested novel approaches involving analysis of complex electrical impedance coupled with seismic-interferometric characterization. A new laboratory experimental facility for simultaneous, multichannel seismic and AC electrical measurements has been developed. We have found that electrical permittivity is a very sensitive parameter to monitor the phase of the stored CO2. Secondly, a novel approach has been developed, which takes advantage of the nonphysical reflections retrieved by seismic interferometry to estimate reliable values of seismic wave velocity and attenuation in the CO2 reservoir, efficiently minimizing the effect of the overburden and removing the detrimental effect of the source-related irreproducibility. Finally, new

  9. Investigation of morphology, electrical behavior (AC and DC) and CO2 gas sensitivity of porous silicon deposited with nanolayers of bromo aluminum phthalocyanine

    NASA Astrophysics Data System (ADS)

    Azim-Araghi, M. E.; Bisadi, Z.

    2012-05-01

    The AC and DC electrical properties of sandwich devices fabricated with silicon (Si), porous silicon (PSi) and nanolayers of bromo aluminum phthalocyanine with aluminum electrodes (Al/Si/Al, Al/Si/PSi/Al, Al/Si/BrAlPc/Al and Al/Si/PSi/BrAlPc/Al) were examined over the voltage, frequency and temperature range of 0-11 mV, 102-105 Hz and 303-423 K respectively. Morphology of the samples was studied via scanning electron microscope (SEM) images and X-ray diffraction (XRD) micrographs. Capacitance is practically independent of frequency (f) in the range of 102-104 Hz, whereas it is extremely frequency dependent for f > 104 Hz. Dissipation factor decreased with increasing frequency to a minimum value and increased noticeably thereafter. Capacitance and dissipation factor are almost independent of temperature; capacitance increases with increasing temperature for T > 380 K. The AC electrical behavior of sandwich devices has been shown to be in agreement with the model of Goswami and Goswami. According to our data the Al contact in sandwich devices is of ohmic type and the tunneling mechanism is applicable in explaining the DC conduction process. The Al/Si/PSi/BrAlPc/Al device, compared to other devices, exhibits the highest sensitivity to CO2.

  10. Interaction of atomized colloid with an ac electric field in a dielectric barrier discharge reactor used for deposition of nanocomposite coatings

    NASA Astrophysics Data System (ADS)

    Profili, Jacopo; Dap, Simon; Levasseur, Olivier; Naude, Nicolas; Belinger, Antoine; Stafford, Luc; Gherardi, Nicolas

    2017-02-01

    Nanocomposite thin films can be obtained by polymerization of a colloidal solution in a dielectric barrier discharge (DBD) at atmospheric pressure. In such a process, the dispersion of nanoparticles into the matrix is driven by the charging, transport, and deposition dynamics of the atomized colloid. This work examines the interaction of atomized TiO2 nanoparticles with ac electric fields in a plane-to-plane dielectric barrier discharge reactor. Experiments are performed with the discharge off to examine transport and deposition phenomena over a wide range of experimental conditions with a fixed particle charge distribution. Scanning electron microscopy reveals that the size distribution of TiO2 nanoparticles collected at different locations along the substrate surface placed on the bottom electrode of the DBD reactor can judiciously be controlled by varying the amplitude and frequency of the ac electric field. These results are also compared to the predictions of a simple particle motion model accounting for the electrostatic force, the gravitational force, and the neutral drag force in the laminar flow. It is found that while the initial charge distribution of atomized particles strongly influences the total deposition yield, its maximal position on the substrate, and the width of the deposited area, the initial size distribution of the particles at the entrance of the reactor mostly changes the size distribution at each position along the substrate surface.

  11. Calculation and measurement of electric field under HVDC transmission lines

    NASA Astrophysics Data System (ADS)

    Kasdi, A.; Zebboudj, Y.; Yala, H.

    2007-03-01

    A stable corona discharge in a two conductors-to-plane configuration is analysed in this paper. A linear biased probe, without end-effect, has been adapted to a linear geometry and is used for the first time to measure the ground-plane current density and electric field during the bipolar corona. The values of the electric field and the current density are maximum under the two coronating conductors and decrease when moving away from them. Furthermore, a hybrid technique is developed to obtain a general solution of the governing equations of the coupled space-charge and electric field problem. The technique is to use the finite-element method (FEM) to solve Poisson's equation, and the method of characteristic (MOC) to find the charge density from a current-continuity relation. The model avoids resorting to the Deutsch assumption. The computed values are in good agreement with experimental data.

  12. Vibration measurement of electrical machines using integrated fibre Bragg gratings

    NASA Astrophysics Data System (ADS)

    Fabian, M.; Borg Bartolo, J.; Ams, M.; Gerada, C.; Sun, T.; Grattan, K. T. V.

    2015-09-01

    In this paper a method to track the rotating force vector set up within the air-gap of radial flux rotating electrical machines using fibre Bragg gratings is reported. The proposed technique offers the potential for simultaneous rotor speed and position monitoring. This specific sensor design, together with other FBG-based multi-parameter measurements, is aimed to create an all-optical sensor solution for electrical machines, reducing the component count of existing systems and addressing noise issues traditionally associated with electrical sensors used. In this work, an optical fibre sensor system has been successfully integrated into an off-the-shelf four-pole 11kW induction motor.

  13. New experiment to measure the electron electric dipole moment

    NASA Astrophysics Data System (ADS)

    Kittle, M.; Burton, T.; Feeney, L.; Heinzen, D. J.

    2004-05-01

    We are building a new experiment to measure the electric dipole moment (edm) of the electron. The experiment will use laser-cooled Cs atoms trapped in two, side-by-side, standing wave, far-off resonance optical dipole force traps. High voltage electrodes will apply opposite polarity electric fields to the two traps. The signature of an edm would be a first-order electric field shift of the atomic Zeeman levels. The traps will be loaded inside a titanium vacuum chamber with atoms captured in optical molasses from a 2D MOT cold atom source. We have paid special attention to the magnetic noise generated by Johnson noise currents of conductors in the design of this apparatus. The apparatus is designed to be sensitive to an electron edm as small as 10-29 e cm. In this presentation, we will discuss the design of our experiment and our experimental progress.

  14. Thermal and Electrical Conductivity Measurements of CDA 510 Phosphor Bronze

    NASA Technical Reports Server (NTRS)

    Tuttle, James E.; Canavan, Edgar; DiPirro, Michael

    2009-01-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, there is significant variation among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). The heat conducted into the JWST instrument stage is dominated by these harnesses, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to just keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment which measured the electrical and thermal conductivity of this material between 4 and 295 Kelvin.

  15. Thermal and Electrical Conductivity Measurements of Cda 510 Phosphor Bronze

    NASA Astrophysics Data System (ADS)

    Tuttle, J.; Canavan, E.; DiPirro, M.

    2010-04-01

    Many cryogenic systems use electrical cables containing phosphor bronze wire. While phosphor bronze's electrical and thermal conductivity values have been published, results vary among different phosphor bronze formulations. The James Webb Space Telescope (JWST) will use several phosphor bronze wire harnesses containing a specific formulation (CDA 510, annealed temper). These harnesses dominate the heat conducted into the JWST instrument stage, and approximately half of the harness conductance is due to the phosphor bronze wires. Since the JWST radiators are expected to keep the instruments at their operating temperature with limited cooling margin, it is important to know the thermal conductivity of the actual alloy being used. We describe an experiment that measured its electrical and thermal conductivity between 4 and 295 Kelvin.

  16. First results from electrical qualification measurements on DEPFET pixel detector

    NASA Astrophysics Data System (ADS)

    Majewski, Petra; Andricek, Ladislav; Lauf, Thomas; Lechner, Peter; Lutz, Gerhard; Reiffers, Jonas; Richter, Rainer; Schaller, Gerhard; Schnecke, Martina; Schopper, Florian; Soltau, Heike; Stefanescu, Alexander; Strüder, Lothar; Treis, Johannes

    2010-07-01

    We report on the first results from a new setup for electrical qualification measurements of DEPFET pixel detector matrices. In order to measure the transistor properties of all pixels, the DEPFET device is placed into a benchtest setup and electrically contacted via a probecard. Using a switch matrix, each pixel of the detector array can be addressed individually for characterization. These measurements facilitate to pre-select the best DEPFET matrices as detector device prior to the mounting of the matrix and allow to investigate topics like the homogeneity of transistor parameters on device, wafer and batch level in order to learn about the stability and reproducibility of the production process. Especially with regard to the detector development for the IXO Wide Field Imager (WFI), this yield learning will be an important tool. The first electrical qualification measurements with this setup were done on DEPFET macropixel detector flight hardware, which will form the FPAs of the Mercury Imaging X-ray Spectrometer (MIXS) on board of the 5th ESA cornerstone mission BepiColombo. The DEPFET array consists of 64×64 macropixel for which the transfer, output and clear characteristics were measured.

  17. Uncertainty analysis for common Seebeck and electrical resistivity measurement systems.

    PubMed

    Mackey, Jon; Dynys, Frederick; Sehirlioglu, Alp

    2014-08-01

    This work establishes the level of uncertainty for electrical measurements commonly made on thermoelectric samples. The analysis targets measurement systems based on the four probe method. Sources of uncertainty for both electrical resistivity and Seebeck coefficient were identified and evaluated. Included are reasonable estimates on the magnitude of each source, and cumulative propagation of error. Uncertainty for the Seebeck coefficient includes the cold-finger effect which has been quantified with thermal finite element analysis. The cold-finger effect, which is a result of parasitic heat transfer down the thermocouple probes, leads to an asymmetric over-estimation of the Seebeck coefficient. A silicon germanium thermoelectric sample has been characterized to provide an understanding of the total measurement uncertainty. The electrical resistivity was determined to contain uncertainty of ±7.0% across any measurement temperature. The Seebeck coefficient of the system is +1.0%/-13.1% at high temperature and ±1.0% near room temperature. The power factor has a combined uncertainty of +7.3%/-27.0% at high temperature and ±7.5% near room temperature. These ranges are calculated to be typical values for a general four probe Seebeck and resistivity measurement configuration.

  18. Electrical-Impedance Tomography for Measuring Material Distributions of Multiphase Flows in Conducting Vessels

    NASA Astrophysics Data System (ADS)

    Liter, S. G.; Torczynski, J. R.; Shollenberger, K. A.; Ceccio, S. L.

    2001-11-01

    An implementation of resistive electrical-impedance tomography (EIT) for measuring material distributions of two-phase flows in vessels with electrically conducting walls is presented. A thin nonconducting rod, with N-1 ring electrodes wrapped around its exterior at equally-spaced axial positions, is inserted into the vessel (i.e., into the interior of the flow). The vessel wall is grounded and serves as the N-th electrode. Current is injected from a ring electrode and exits to the vessel wall, and the resulting voltages at all ring electrodes are recorded. Each ring electrode is used in turn for current injection, and the collection of all measured voltages comprises a data set. Multiple data sets are used to numerically reconstruct the time-averaged impedance distribution within the vessel, from which the material distribution is inferred. Design issues, including the size, spacing, and number of the ring electrodes, are considered. An experiment in which the rod is inserted coaxially into a vertical pipe is presented, and bubble-column applications are discussed. *Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy under Contract DE-AC04-94AL85000.

  19. Electric and Magnetic Field Measurements in High Energy Electron Beam Diode Plasmas using Optical Spectroscopy

    NASA Astrophysics Data System (ADS)

    Johnston, Mark; Patel, Sonal; Kiefer, Mark; Biswas, S.; Doron, R.; Stambulchik, E.; Bernshtam, V.; Maron, Yitzhak

    2016-10-01

    The RITS accelerator (5-11MV, 100-200kA) at Sandia National Laboratories is being used to evaluate the Self-Magnetic Pinch (SMP) diode as a potential flash x-ray radiography source. This diode consists of a small, hollowed metal cathode and a planar, high atomic mass anode, with a small vacuum gap of approximately one centimeter. The electron beam is focused, due to its self-field, to a few millimeters at the target, generating bremsstrahlung x-rays. During this process, plasmas form on the electrode surfaces and propagate into the vacuum gap, with a velocity of a 1-10 cm's/microseconds. These plasmas are measured spectroscopically using a Czerny-Turner spectrometer with a gated, ICCD detector, and input optical fiber array. Local magnetic and electric fields of several Tesla and several MV/cm were measured through Zeeman splitting and Stark shifting of spectral lines. Specific transitions susceptible to quantum magnetic and electric field effects were utilized through the application of dopants. Data was analyzed using detailed, time-dependent, collisional-radiative (CR) and radiation transport modeling. Recent results will be presented. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  20. DOE Fundamentals Handbook: Electrical Science, Volume 1

    SciTech Connect

    Not Available

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of electrical theory, terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors, and generators; AC power and reactive components; batteries; AC and DC voltage regulators; transformers; and electrical test instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  1. DOE Fundamentals Handbook: Electrical Science, Volume 4

    SciTech Connect

    Not Available

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding of electrical theory, terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors, and generators; AC power and reactive transformers; and electrical test components; batteries; AC and DC voltage regulators; instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  2. Effect of Voltage Measurement on the Quantitative Identification of Transverse Cracks by Electrical Measurements

    PubMed Central

    Selvakumaran, Lakshmi; Lubineau, Gilles

    2016-01-01

    Electrical tomography can be used as a structural health monitoring technique to identify different damage mechanisms in composite laminates. Previous work has established the link between transverse cracking density and mesoscale conductivity of the ply. Through the mesoscale relationship, the conductivity obtained from electrical tomography can be used as a measure of the transverse cracking density. Interpretation of this measure will be accurate provided the assumptions made during homogenization are valid. One main assumption of mesoscale homogenization is that the electric field is in the plane. Here, we test the validity of this assumption for laminates with varying anisotropy ratios and for different distances between the cracked ply and surface that is instrumented with electrodes. We also show the equivalence in electrical response between measurements from cracked laminates and their equivalent mesoscale counterparts. Finally, we propose some general guidelines on the measurement strategy for maximizing the accuracy of transverse cracks identification. PMID:27023542

  3. Cutting force measurement of electrical jigsaw by strain gauges

    NASA Astrophysics Data System (ADS)

    Kazup, L.; Varadine Szarka, A.

    2016-11-01

    This paper describes a measuring method based on strain gauges for accurate specification of electric jigsaw's cutting force. The goal of the measurement is to provide an overall perspective about generated forces in a jigsaw's gearbox during a cutting period. The lifetime of the tool is affected by these forces primarily. This analysis is part of the research and development project aiming to develop a special linear magnetic brake for realizing automatic lifetime tests of electric jigsaws or similar handheld tools. The accurate specification of cutting force facilitates to define realistic test cycles during the automatic lifetime test. The accuracy and precision resulted by the well described cutting force characteristic and the possibility of automation provide new dimension for lifetime testing of the handheld tools with alternating movement.

  4. Global ionospheric electric field measurements in April 1978

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

  5. [Measurement of chemical agents in metallurgy field: electric steel plant].

    PubMed

    Cottica, D; Grignani, E; Ghitti, R; Festa, D; Apostoli, P

    2012-01-01

    The steel industry maintains its important position in the context of the Italian production involving thousands of workers. The iron and steel processes are divided into primary steel industry, production of intermediate minerals, and secondary steel, scrap from the production of semi-finished industrial and consumer sector (metal inserted into components and metal used for dissipative uses, primarily coatings) and industrial waste. The paper presents the results of environmental monitoring carried out in some electric steel plant for the measurement of airborne chemicals that characterize the occupational exposure of workers employed in particular area like electric oven, to treatment outside the furnace, continuous casting area. For the sampling of the pollutants were used both personal and in fixed positions samplers. The pollutants measured are those typical of steel processes inhalable dust, metals, respirable dust, crystalline silica, but also Polycyclic Aromatic Hydrocarbons (PAH), polychlorinated dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs).

  6. Proximity- and Astigmatism-Tolerant Testsites For Electrical Linewidth Measurement

    NASA Astrophysics Data System (ADS)

    Lin, Burn J.

    1989-07-01

    Electrical linewidth measurement is well-known for high precision and throughput. However, the standard four-point probe testsite is only useful for measuring the width of an isolated conducting line. Line-and-space and isolated spaces can be simulated satisfactorily by adding dummy lines parallel to the active line but weak links or potential electrical shorting situations often prematurely cause these structures to fail before their true limits are reached. In this paper, fully wrapped proximity- and astigmatism-tolerant designs for line-and-space and isolated spaces are shown. They have been successfully demonstrated with printed images. An application in evaluating the exposure-defocus window of a one-layer i-line resist using the proximity-tolerant testsites is given.

  7. Reliable, Efficient and Cost-Effective Electric Power Converter for Small Wind Turbines Based on AC-link Technology

    SciTech Connect

    Darren Hammell; Mark Holveck; DOE Project Officer - Keith Bennett

    2006-08-01

    Grid-tied inverter power electronics have been an Achilles heel of the small wind industry, providing opportunity for new technologies to provide lower costs, greater efficiency, and improved reliability. The small wind turbine market is also moving towards the 50-100kW size range. The unique AC-link power conversion technology provides efficiency, reliability, and power quality advantages over existing technologies, and Princeton Power will adapt prototype designs used for industrial asynchronous motor control to a 50kW small wind turbine design.

  8. Total AC losses in twisted and untwisted multifilamentary Bi-2223 superconducting tapes carrying AC transport current in AC longitudinal magnetic field

    NASA Astrophysics Data System (ADS)

    Amemiya, Naoyuki; Jin, Feng; Jiang, Zhenan; Shirai, Shunsuke; ten Haken, Bennie; Rabbers, Jan-Jaap; Ayai, Naoki; Hayashi, Kazuhiko

    2003-03-01

    In some electrical apparatuses, superconducting tapes are exposed to the longitudinal magnetic field. In this work, AC losses were measured in twisted and untwisted Bi-2223 tapes carrying AC transport current in the AC longitudinal magnetic field. In twisted tapes, the transport, magnetization and total losses depend on the relative direction of the longitudinal magnetic field to the direction of the transport current, while the field direction does not influence the AC loss characteristics in untwisted tapes. In the Z-twisted tapes, the total AC loss is larger in the longitudinal magnetic field that is anti-parallel to the transport current than in the longitudinal magnetic field of another direction. Numerical analysis shows that this field direction dependence of the total AC loss results from the change in the current distribution. In the longitudinal magnetic field that is anti-parallel to the transport current, the total AC loss in the Z-twisted tape is more than that in the untwisted tape. This dependence on the field direction is reversed in S-twisted tapes. It is to be noted that the twist increases the total AC loss in a longitudinal magnetic field of a certain direction, while it reduces the AC loss in the transverse magnetic field.

  9. AC losses in a HTS coil carrying DC current in AC external magnetic field

    NASA Astrophysics Data System (ADS)

    Ogawa, J.; Zushi, Y.; Fukushima, M.; Tsukamoto, O.; Suzuki, E.; Hirakawa, M.; Kikukawa, K.

    2003-10-01

    We electrically measured AC losses in a Bi2223/Ag-sheathed pancake coil excited by a DC current in AC external magnetic field. Losses in the coil contain two kinds of loss components that are the magnetization losses and dynamic resistance losses. In the measurement, current leads to supply a current to the coil were specially arranged to suppress electromagnetic coupling between the coil current and the AC external magnetic field. A double pick-up coils method was used to suppress a large inductive voltage component contained in voltage signal for measuring the magnetization losses. It was observed that the magnetization losses were dependent on the coil current and that a peak of a curve of the loss factor vs. amplitude of the AC external magnetic field shifted to lower amplitude of the AC magnetic field as the coil current increased. This result suggests the full penetration magnetic field of the coil tape decreases as the coil current increases. The dynamic resistance losses were measured by measuring a DC voltage appearing between the coil terminals. It was observed that the DC voltage appearing in the coil subject to the AC external magnetic field was much larger than that in the coil subject to DC magnetic field.

  10. The calibration of a model for simulating the thermal and electrical performance of a 2.8 kW AC solid-oxide fuel cell micro-cogeneration device

    NASA Astrophysics Data System (ADS)

    Beausoleil-Morrison, Ian; Lombardi, Kathleen

    The concurrent production of heat and electricity within residential buildings using solid-oxide fuel cell (SOFC) micro-cogeneration devices has the potential to reduce primary energy consumption, greenhouse gas emissions, and air pollutants. A realistic assessment of this emerging technology requires the accurate simulation of the thermal and electrical production of SOFC micro-cogeneration devices concurrent with the simulation of the building, its occupants, and coupled plant components. The calibration of such a model using empirical data gathered from experiments conducted with a 2.8 kW AC SOFC micro-cogeneration device is demonstrated. The experimental configuration, types of instrumentation employed, and the operating scenarios examined are treated. The propagation of measurement uncertainty into the derived quantities that are necessary for model calibration are demonstrated by focusing upon the SOFC micro-cogeneration system's gas-to-water heat exchanger. The calibration coefficients necessary to accurately simulate the thermal and electrical performance of this prototype device are presented and the types of analyses enabled to study the potential of the technology are demonstrated.

  11. 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.

  12. Digital ac monitor

    DOEpatents

    Hart, George W.; Kern, Jr., Edward C.

    1987-06-09

    An apparatus and method is provided for monitoring a plurality of analog ac circuits by sampling the voltage and current waveform in each circuit at predetermined intervals, converting the analog current and voltage samples to digital format, storing the digitized current and voltage samples and using the stored digitized current and voltage samples to calculate a variety of electrical parameters; some of which are derived from the stored samples. The non-derived quantities are repeatedly calculated and stored over many separate cycles then averaged. The derived quantities are then calculated at the end of an averaging period. This produces a more accurate reading, especially when averaging over a period in which the power varies over a wide dynamic range. Frequency is measured by timing three cycles of the voltage waveform using the upward zero crossover point as a starting point for a digital timer.

  13. Digital ac monitor

    DOEpatents

    Hart, G.W.; Kern, E.C. Jr.

    1987-06-09

    An apparatus and method is provided for monitoring a plurality of analog ac circuits by sampling the voltage and current waveform in each circuit at predetermined intervals, converting the analog current and voltage samples to digital format, storing the digitized current and voltage samples and using the stored digitized current and voltage samples to calculate a variety of electrical parameters; some of which are derived from the stored samples. The non-derived quantities are repeatedly calculated and stored over many separate cycles then averaged. The derived quantities are then calculated at the end of an averaging period. This produces a more accurate reading, especially when averaging over a period in which the power varies over a wide dynamic range. Frequency is measured by timing three cycles of the voltage waveform using the upward zero crossover point as a starting point for a digital timer. 24 figs.

  14. AC Electrical Conduction of Cr-Doped SrTiO3 Thin Films with an Oxygen-Deficient Interface Layer

    NASA Astrophysics Data System (ADS)

    Phan, Bach Thang; Eom, Ki Tae; Lee, Jaichan

    2017-01-01

    The ac electrical conduction of Cr-doped SrTiO3 thin films with an oxygen-deficient interface layer was investigated as a function of temperature and frequency. The Cr-doped SrTiO3 (Cr-STO) thin films with an ultra-thin (˜2 nm) oxygen-deficient layer inserted between the top electrode and the Cr-STO layer exhibited two ac conduction mechanisms, i.e., variable-range hopping and small-polaron hopping conduction, accompanied by a relaxation process. Since high oxygen deficiency induces large lattice distortion in the depletion layer, the first relaxation process occurs at low frequencies in the thin oxygen depletion layer Cr-SrTiO3-δ , and the corresponding conduction behavior follows the small-polaron tunneling model. In the high frequency range, an additional relaxation process is involved and is associated with the variable-range hopping between the localized states in the band gap of the thick Cr-SrTiO3 layer.

  15. Measurement of limb blood flow by electrical impedance plethysmography.

    PubMed Central

    Porter, J. M.; Swain, I. D.; Shakespeare, P. G.

    1985-01-01

    Limb blood flow has been measured in 72 individuals by the noninvasive technique of electrical impedance plethysmography. Venous occlusion was not used. Blood flow was measured in 230 limbs in which 195 limbs were either in normal individuals or the clinically normal limbs of patients (normal limbs). Thirty-five limbs were clinically abnormal. Measurements on limbs with clinical abnormalities showed that blood flow values often fell within the limits of the normal range. However 3 cases of known vascular injury and 2 cases studied after hand surgery under tourniquet showed lowered blood flow values by comparison with the unaffected limb. A simultaneously recorded range of cardiac output and stroke volume measurements gave similar results to those obtained in a previous, unconnected study. Images Fig. 1 PMID:4004047

  16. Towards a new measurement of the neutron electric dipole moment

    NASA Astrophysics Data System (ADS)

    Altarev, I.; Ban, G.; Bison, G.; Bodek, K.; Burghoff, M.; Cvijovic, M.; Daum, M.; Fierlinger, P.; Gutsmiedl, E.; Hampel, G.; Heil, W.; Henneck, R.; Horras, M.; Khomutov, N.; Kirch, K.; Kistryn, St.; Knappe-Grüneberg, S.; Knecht, A.; Knowles, P.; Kozela, A.; Kratz, J. V.; Kuchler, F.; Kuźniak, M.; Lauer, T.; Lauss, B.; Lefort, T.; Mtchedlishvili, A.; Naviliat-Cuncic, O.; Paul, S.; Pazgalev, A. S.; Petzoldt, G.; Pierre, E.; Plonka-Spehr, C.; Quéméner, G.; Rebreyend, D.; Roccia, S.; Rogel, G.; Sander-Thoemmes, T.; Schnabel, A.; Severijns, N.; Sobolev, Yu.; Stoepler, R.; Trahms, L.; Weis, A.; Wiehl, N.; Zejma, J.; Zsigmond, G.

    2009-12-01

    The effort towards a new measurement of the neutron electric dipole moment (nEDM) at the Paul Scherrer Institut's (PSI) new high intensity source of ultracold neutrons (UCN) is described. The experimental technique relies on Ramsey's method of separated oscillatory fields, using UCN in vacuum with the apparatus at ambient temperature. In the first phase, R&D towards the upgrade of the RAL/Sussex/ILL apparatus is being performed at the Institut Laue-Langevin (ILL). In the second phase the apparatus, moved from ILL to PSI, will allow an improvement in experimental sensitivity by a factor of 5. In the third phase, a new spectrometer should gain another order of magnitude in sensitivity. The improvements will be mainly due to (1) much higher UCN intensity, (2) improved magnetometry and magnetic field control, and (3) a double chamber configuration with opposite electric field directions.

  17. Accuracy testing of electric groundwater-level measurement tapes

    USGS Publications Warehouse

    Jelinski, Jim; Clayton, Christopher S.; Fulford, Janice M.

    2015-01-01

    The accuracy tests demonstrated that none of the electric-tape models tested consistently met the suggested USGS accuracy of ±0.01 ft. The test data show that the tape models in the study should give a water-level measurement that is accurate to roughly ±0.05 ft per 100 ft without additional calibration. To meet USGS accuracy guidelines, the electric-tape models tested will need to be individually calibrated. Specific conductance also plays a part in tape accuracy. The probes will not work in water with specific conductance values near zero, and the accuracy of one probe was unreliable in very high conductivity water (10,000 microsiemens per centimeter).

  18. The Electrical Structure of Terrestrial Dust Devils: Implications of Multiple Vertical Measurements of the Electric Field

    NASA Astrophysics Data System (ADS)

    Delory, G. T.; Farrell, W. M.; Hillard, B.; Renno, N. O.; Smith, P.; Marshall, J. R.; Eatchel, A.

    2002-12-01

    In this work we discuss observations of the electrical structure of dust devils made in the summer of 2001 and 2002 during the Mars Atmosphere and Dust in the Optical and Radio (MATADOR) field campaign outside of Tucson, Arizona. While it has long been known that Terrestrial dust devils can support large electric fields of magnitudes of up to 10 kV/m or more, the fundamental features of the charging mechanism have yet to be fully characterized from an observational perspective. If triboelectric charging is indeed responsible for the generation of significant electric potentials within the dust column, some means of large scale stratification and/or separation of charges is necessary to maintain these fields. To help address this question and elucidate the overall vertical charge distribution of dust devils, we used two field mill instruments to make simultaneous measurements of electric fields both at the surface and 1 meter above the ground. At present, our observations indicate that the dust grains become negatively charged at or very near the air-surface interface. The largest devils recorded (30 m diameter) show a region of enhanced positive electric fields persisting for minutes after the event has passed, indicating the possible presence of a large scale collection of airborne positive charges following the negatively charged dust column. Based on our observations, the key to the charging mechanism appears to reside in the bottom of the saltation layer where the bulk of collisional frictional charging is likely to occur. We discuss the implications of these observations for theories of Terrestrial dust devil electrification and for our understanding of similar processes on Mars.

  19. Efficacy of low level electric current (A-C) for controlling quagga mussles in the Welland Canal

    SciTech Connect

    Fears, C.; Mackie, G.L.

    1995-06-01

    The efficacy of systems (for which patents are pending) which use low-voltage A-C currents for preventing settlement and attachment by zebra mussels were tested with steel rods and plates placed near the intake of a pulp and paper plant in the Welland Canal at Thorold, Ontario. Six racks made of 16 ft. (4.9 m), 2x4s (5.1 x 10.2 cm) were placed into the Welland Canal on August 5, 1994. One rack had 1/8th in (3.2 mm) diam x 12 in (30.5 cm) long steel rods, each separated by 2 in (5.1 cm) attached to pressure treated wood and concrete blocks and an A-C current of 16 v (or 8 v/in); rack 2 had steel rods of the same configuration but 12 v (or 6 v/in) was applied; rack 3 was identical to these but no current was applied and was used as a rod control. The remaining three racks had steel plates, each plate being 3 in (7.6 cm) wide X 24 in (61 cm) long X 1/4 in (6.4 mm) thick and separated by 2 in (5.1 cm); one had 12 v applied (or 6 v/in), another had 16 v applied (or 8 v/in), and the third had no current and was used as a plate control. The racks were placed on the upstream and downstream side of the intake at a depth of about 7 ft (2.1 m) where the mussels populations were heaviest (as determined by SCUBA diving). All mussels were quagga mussels (Dreissena bugensis). The racks were pulled in mid November after settlement was complete and the results showed: (1) complete prevention of settlement of both new recruits and translocators at 8 volts/in with steel rods on both wood and concrete surfaces and with steel plate trash bars; (2) partial prevention of settlement at 6 volts/in with steel rods on both wood and concrete surfaces and steel plates; and (3) that, at current kilowatt hr rates, total efficacy at 8 volts/in would cost approximately $10.80/day/1000 sq ft using rods to protect concrete walls and about $16.32/day/1000 sq ft to protect 3 in wide x 1/4 in thick trash bars. These costs can be reduced even further with pulse dosed AC currents.

  20. A Novel Inductor-less DC-AC Cascaded H-bridge Multilevel Boost Inverter for Electric/Hybrid Electric Vehicle Applications

    SciTech Connect

    Du, Zhong; Ozpineci, Burak; Tolbert, Leon M; Chiasson, John N

    2007-01-01

    This paper presents an inductorless cascaded H- bridge multilevel boost inverter for EV and HEV applications. Currently available power inverter systems for HEVs use a DC- DC boost converter to boost the battery voltage for a traditional 3-phase inverter. The present HEV traction drive inverters have low power density, are expensive, and have low efficiency because they need a bulky inductor. An inductorless cascaded H-bridge multilevel boost inverter for EV and HEV applications is proposed in this paper. Traditionally, each H-bridge needs a DC power supply. The proposed inductorless cascaded H-bridge multilevel boost inverter uses a standard 3-leg inverter (one leg for each phase) and an H-bridge in series with each inverter leg which uses a capacitor as the DC power source. Fundamental switching scheme is used to do modulation control and to produce a 5-level phase voltage. Experiments show that the proposed inductorless DC-AC cascaded H-bridge multilevel boost inverter can output a boosted AC voltage.

  1. Introducing AC inductive reactance with a power tool

    NASA Astrophysics Data System (ADS)

    Bryant, Wesley; Baker, Blane

    2016-09-01

    The concept of reactance in AC electrical circuits is often non-intuitive and difficult for students to grasp. In order to address this lack of conceptual understanding, classroom exercises compare the predicted resistance of a power tool, based on electrical specifications, to measured resistance. Once students discover that measured resistance is smaller than expected, they are asked to explain these observations using previously studied principles of magnetic induction. Exercises also introduce the notion of inductive reactance and impedance in AC circuits and, ultimately, determine self-inductance of the motor windings within the power tool.

  2. Gate-opening gas adsorption and host-guest interacting gas trapping behavior of porous coordination polymers under applied AC electric fields.

    PubMed

    Kosaka, Wataru; Yamagishi, Kayo; Zhang, Jun; Miyasaka, Hitoshi

    2014-09-03

    The gate-opening adsorption behavior of the one-dimensional chain compound [Ru2(4-Cl-2-OMePhCO2)4(phz)] (1; 4-Cl-2-OMePhCO2(-) = 4-chloro-o-anisate; phz = phenazine) for various gases (O2, NO, and CO2) was electronically monitored in situ by applying ac electric fields to pelletized samples attached to a cryostat, which was used to accurately control the temperature and gas pressure. The gate-opening and -closing transitions induced by gas adsorption/desorption, respectively, were accurately monitored by a sudden change in the real part of permittivity (ε'). The transition temperature (TGO) was also found to be dependent on the applied temperature and gas pressure according to the Clausius-Clapeyron equation. This behavior was also observed in the isostructural compound [Rh2(4-Cl-2-OMePhCO2)4(phz)] (2), which exhibited similar gate-opening adsorption properties, but was not detected in the nonporous gate-inactive compound [Ru2(o-OMePhCO2)4(phz)] (3). Furthermore, the imaginary part of permittivity (ε″) effectively captured the electronic perturbations of the samples induced by the introduced guest molecules. Only the introduction of NO resulted in the increase of the sample's electronic conductivity for 1 and 3, but not for 2. This behavior indicates that electronic host-guest interactions were present, albeit very weak, at the surface of sample 1 and 3, i.e., through grain boundaries of the sample, which resulted in perturbation of the conduction band of this material's framework. This technique involving the in situ application of ac electric fields is useful not only for rapidly monitoring gas sorption responses accompanied by gate-opening/-closing structural transitions but also potentially for the development of molecular framework materials as chemically driven electronic devices.

  3. Surface electrical properties experiment, part 1. [for measuring lunar surface electrical properties

    NASA Technical Reports Server (NTRS)

    Kupfer, W. S. (Compiler)

    1973-01-01

    The design evolution, hardware development, and production history of the surface electrical properties (SEP) experiment are discussed. The SEP transmitter and receiver were designed to be used on the lunar surface during the Apollo 17 mission. The equipment was used to measure lunar surface electrical properties over traverses totalling more than 8 kilometers, for a duration of more than 100 minutes. A comprehensive outline of the techniques, is given along with a simplified detailed breakdown of equipment description and function to outline the principles of operation. A history of the design evolution with trade-off criteria and emphasis on changes caused by decisions reached in solving problems inherent in a fast-paced development program are presented from the viewpoint of overall design concept and in detail for each item of deliverable hardware. There is a brief account of lunar operations.

  4. Atmospheric Electric Field measurements at Eastern North Atlantic ARM Climate Research Facility: Global Electric Circuit Evolution

    NASA Astrophysics Data System (ADS)

    Lopes, Francisco; Silva, Hugo; Nitschke, Kim; Azevedo, Eduardo

    2016-04-01

    The Eastern North Atlantic (ENA) facility of the ARM programme (established an supported by the U.S. Department of Energy with the collaboration of the local government and University of the Azores), is located at Graciosa Island of the Azores Archipelago (39° N; 28° W). It constitutes a strategic observatory for Atmospheric Electricity since it is located in the Atlantic Ocean basin exposed to clean marine aerosol conditions which reduces the well known spectral signature of atmospheric pollution and enables the study of the so called Global Electrical Circuit (GEC). First evidences of the existence of a GEC affecting the Earth's Electric Environment has retrieved by the Carnegie cruise expedition, in what became known as the Carnegie Curve. Those measurements were made in the Ocean in several campaigns and the present studies aims at reconsidering measurements in similar conditions but in a long-term basis, at least 5 years. This will contribute to the understanding of the long-term evolution of the Ionospheric Potential (IP). In literature there is theoretical evidence that it is decreasing IP in strength, but that conjecture is still lacking valid experimental evidence. Moreover, to clearly identify the GEC signal two effects must be taken into account: the effect of surface radon gas variation, because the Azores Archipelago is a seismic active region the possible influence of Earthquakes cannot be discarded easily; the effect of short-term solar activity on the Atmospheric Electricity modulation, solar flares emitting solar particles (e.g., solar energetic protons) need to be considered in this study.

  5. Analyses of temperature-dependent interface states, series resistances, and AC electrical conductivities of Al/p—Si and Al/Bi4Ti3O12/p—Si structures by using the admittance spectroscopy method

    NASA Astrophysics Data System (ADS)

    Mert, Yıldırım; Perihan, Durmuş; Şemsettin, Altındal

    2013-10-01

    In this study, Al/p—Si and Al/Bi4Ti3O12/p—Si structures are fabricated and their interface states (Nss), the values of series resistance (Rs), and AC electrical conductivity (σac) are obtained each as a function of temperature using admittance spectroscopy method which includes capacitance—voltage (C—V) and conductance—voltage (G—V) measurements. In addition, the effect of interfacial Bi4Ti3O12 (BTO) layer on the performance of the structure is investigated. The voltage-dependent profiles of Nss and Rs are obtained from the high-low frequency capacitance method and the Nicollian method, respectively. Experimental results show that Nss and Rs, as strong functions of temperature and applied bias voltage, each exhibit a peak, whose position shifts towards the reverse bias region, in the depletion region. Such a peak behavior is attributed to the particular distribution of Nss and the reordering and restructuring of Nss under the effect of temperature. The values of activation energy (Ea), obtained from the slope of the Arrhenius plot, of both structures are obtained to be bias voltage-independent, and the Ea of the metal-ferroelectric-semiconductor (MFS) structure is found to be half that of the metal—semiconductor (MS) structure. Furthermore, other main electrical parameters, such as carrier concentration of acceptor atoms (NA), built-in potential (Vbi), Fermi energy (EF), image force barrier lowering (Δ Φb), and barrier height (Φb), are extracted using reverse bias C-2—V characteristics as a function of temperature.

  6. The Study of Electron Coherence Effects in Metallic Systems with High Frequency AC Electric Fields: Weak Localization and Mesoscopic Photovoltaic Effects.

    NASA Astrophysics Data System (ADS)

    Liu, Jin

    We have studied the effect of a high-frequency microwave electric field on electron phase coherence in thin Sb films and wires. The phase coherence is monitored through the effect of weak localization on the conductance. Through careful experimental design, we were able to calibrate the high frequency electric field. The ac effect was separated from the Joule heating with either dc measurements or the application of a magnetic field. This has made it possible to make a detailed, quantitative comparison with the theory with no free parameters. We have found good agreements between the experiments and the theory for both one and two dimensional cases. We have used the simple dc heating experiment to study the electron heating effects in Sb films. The electron temperature was reflected in the resistance, as an especially striking manner, to be quite different from the lattice temperature. This experiment was also used to study the electron-phonon scattering time in thin Sb films in the temperature range 1-4K. The magnitude of the scattering time is in reasonable accord with the theory, while the temperature dependence is of the form tau_{E_{ph}} ~ T^{-alpha }, with alpha ~ 1.4. The value of alpha appears to be significantly smaller than predicted by the theory, and is not understood. We have also studied the high frequency heating effects of thin AuPd, AuFe, and Au films at low temperatures. The analysis of the experiments yield consistent results with the theory for AuPd films with high values of the sheet resistance. However, for low-sheet-resistance films of AuPd, AuFe, and Au, the analysis suggests either that Joule heating is suppressed at microwave frequencies (as compared with that found for the same field strength at lower frequencies), or that a microwave field enhances the contribution of electron-electron interactions to the resistance. Either of these results would be at odds with current theories. Another experiment in which we were involved was the

  7. Research recommendations for ac interfacing between electric utility transmission and distribution systems and wind, photovoltaics, and OTEC energy systems

    NASA Astrophysics Data System (ADS)

    Longrigg, P.; Buell, E. H.

    1985-03-01

    Work that deals semiquantitatively with many integration problems that may have to be solved as wind, photovoltaic, and ocean energy systems are tied into electrical transmission utility grids is documented. The problems that will arise as these distributed storage and generation (DSG) energy systems are integrated into the electric utility grids are not yet fully known, and their extent may depend on the level of penetration of the DSGs into the grid network. Aspects of DSG integration covered are fuse and relay coordination, harmonics, communications, control protocols, safety, and artificial intelligence (computer driven controls). An appendix on the effects of electromagnetic pulse is also included.

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

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1972-01-01

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

  9. Microbial Sulfate Reduction Measured by an Automated Electrical Impedance Technique

    NASA Technical Reports Server (NTRS)

    Oremland, R. S.; Silverman, M. P.

    1979-01-01

    Electrical impedance measurements are used to investigate the rates of sulfate reduction by pure cultures of and sediments containing sulfur-reducing bacteria. Changes in the electrical impedance ratios of pure cultures of Desulfovibrio aestuarii and samples of reduced sediments from San Francisco Bay were measured by a Bactometer 32, and sulfate reduction was followed by measuring the incorporation of (S-35) sulfate into metal sulfides. The growth of the bacteria in pure culture is found to result in an increase of 0.2200 in the impedance ratio within 24 h, accompanied by increases in protein, ATP, sulfide and absorptance at 660 nm, all of which are inhibited by the addition of molybdate. Similar responses were observed in the sediments, although impedance ratio responses were not completely inhibited upon the addition of molybdate, due to the presence of nonsulfate-respiring microorganisms. Experiments conducted with sterile media and autoclaved sediments indicate that the presence of H2S together with iron is responsible for the impedance effect, and sulfate reduction rates ranging between 0.85 and 1.78 mmol/l per day are estimated for the sediments by the impedance technique.

  10. Estimating of pulsed electric fields using optical measurements.

    SciTech Connect

    Flanagan, Timothy McGuire; Chantler, Gary.

    2013-09-01

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

  11. ELECTRICAL AND ELECTRONIC INDUSTRIAL CONTROL. A-C CONVENTIONAL MAGNETIC MOTOR CONTROL, PART II, UNIT 6, ASSIGNMENTS.

    ERIC Educational Resources Information Center

    SUTTON, MACK C.

    THIS STUDY GUIDE IS FOR INDIVIDUAL STUDENT USE IN STUDYING ALTERNATING CURRENT CONVENTIONAL MAGNETIC MOTOR CONTROL IN ELECTRICAL-ELECTRONIC PROGRAMS. IT WAS DEVELOPED BY AN INSTRUCTIONAL MATERIALS SPECIALIST AND ADVISERS. EACH OF THE 10 ASSIGNMENT SHEETS PROVIDES THE LESSON SUBJECT, PURPOSE, INTRODUCTORY INFORMATION, STUDY REFERENCES,…

  12. ELECTRICAL AND ELECTRONIC INDUSTRIAL CONTROL. A-C CONVENTIONAL MAGNETIC MOTOR CONTROL, PART I, UNIT 5, INSTRUCTOR'S GUIDE.

    ERIC Educational Resources Information Center

    SUTTON, MACK C.

    THIS GUIDE IS FOR TEACHER USE IN DIRECTING INDIVIDUAL STUDY OF ALTERNATING CURRENT CONVENTIONAL MAGNETIC MOTOR CONTROL IN ELECTRICAL-ELECTRONIC PROGRAMS. IT WAS DEVELOPED BY AN INSTRUCTIONAL MATERIALS SPECIALIST AND ADVISERS. EACH OF THE 10 INSTRUCTOR'S SHEETS GIVES THE LESSON SUBJECT, PURPOSE, INTRODUCTORY INFORMATION, REFERENCES, AND…

  13. ELECTRICAL AND ELECTRONIC INDUSTRIAL CONTROL. A-C CONVENTIONAL MAGNETIC MOTOR CONTROL, PART I, UNIT 5, ASSIGNMENTS.

    ERIC Educational Resources Information Center

    SUTTON, MACK C.

    THIS GUIDE IS FOR INDIVIDUAL STUDENT USE IN STUDYING ALTERNATING CURRENT CONVENTIONAL MAGNETIC MOTOR CONTROL IN ELECTRICAL-ELECTRONIC PROGRAMS. IT WAS DEVELOPED BY AN INSTRUCTIONAL MATERIALS SPECIALIST AND ADVISERS. EACH OF THE 10 ASSIGNMENT SHEETS PROVIDES THE LESSON SUBJECT, PURPOSE, INTRODUCTORY INFORMATION, STUDY REFERENCES, SUPPLEMENTARY…

  14. ELECTRICAL AND ELECTRONIC INDUSTRIAL CONTROL. A-C CONVENTIONAL MAGNETIC MOTOR CONTROL, PART II, UNIT 6, INSTRUCTOR'S GUIDE.

    ERIC Educational Resources Information Center

    SUTTON, MACK C.

    THIS GUIDE IS FOR TEACHER USE IN DIRECTING INDIVIDUAL STUDY OF ALTERNATING CURRENT CONVENTIONAL MAGNETIC MOTOR CONTROL IN ELECTRICAL-ELECTRONIC PROGRAMS. IT WAS DEVELOPED BY AN INSTRUCTIONAL MATERIALS SPECIALIST AND ADVISERS. EACH OF THE 10 INSTRUCTOR'S SHEETS GIVES THE LESSON SUBJECT, PURPOSE, INTRODUCTORY INFORMATION, REFERENCES, SUPPLEMENTARY…

  15. Charged dendrimers under the action of AC electric fields: Breathing characteristics of molecular size, polarizations, and ion distributions

    NASA Astrophysics Data System (ADS)

    Das, Ashok K.; Hsiao, Pai-Yi

    2015-02-01

    Langevin dynamics simulations are performed to study the response of charged dendrimers in alternating current electric fields in 3:1 salt solutions. Time evolutions of molecular size show breathing characteristics which take saw-tooth-like patterns in square-wave electric fields and undulated sine-function ones in sine-wave fields. Detailed study reveals how the dendrimer and condensed ions oscillate in the electric fields, which result in polarization of the molecule. To effect a significant deformation of the dendrimer, the applied field amplitude must be larger than some critical strength Ecrit and the field frequency smaller than a threshold fcrit. The response behavior is characterized by two relaxation times in square-wave fields, both of which decrease linearly with the strong field strength larger than Ecrit. In sine-wave fields, the molecular size exhibits interesting hysteretic behavior in plotting the curves with the field variation. A Maxwell-Wagner type polarization theory is derived and proved by simulations, which connects fcrit with the strength of the applied electric field.

  16. Theory of dielectrophoresis and aggregation in suspensions of highly polarized particles subjected to high-gradient AC electric fields

    NASA Astrophysics Data System (ADS)

    Jacqmin, David; Khusid, Boris; Acrivos, Andreas

    2001-11-01

    The proposed mathematical model of electro-hydrodynamic phenomena consists of strongly coupled field and flow equations supplemented by constitutive equations for the dielectric polarization and the field-induced contribution to the energy and stresses in a suspension in the presence of a time-varying electric field. The suspension is viewed as an effective Newtonian fluid with a concentration-dependent viscosity. The long-range hydrodynamic interactions of the particles subjected to shear are incorporated through the concentration dependence of the suspension viscosity, the hindrance function in the expression for the particle settling velocity, and the shear-induced diffusion of the particles. For the electric energy and stress, we employed the constitutive equations of our microscopic theory for the case of strong electric energy dissipation. The equation for the total particle flux includes the flux induced by the electric force exerted on a particle due to the gradient of its chemical potential in a spatially non-uniform electric field, the flux generated by the buoyancy force, and the particle shear-diffusion. We consider the specific case of low particle Reynolds numbers which is relevant to our current experiments. We investigated the situation of "heterogeneous aggregation" when the field-induced phase transitions occur in a thin layer adjacent to the electrodes. By comparing our theoretical predictions with the results of experiments on a rotating channel, we demonstrated that the model is capable of predicting a wide range of physical processes in a suspension of highly polarizable particles, in particular, the formation of highly concentrated particle layers on both the high-voltage and the grounded electrodes.

  17. Nondestructive evaluation of composite materials by electrical resistance measurement

    NASA Astrophysics Data System (ADS)

    Mei, Zhen

    This dissertation investigates electrical resistance measurement for nondestructive evaluation of carbon fiber (CF) reinforced polymer matrix composites. The method involves measuring the DC electrical resistance in either the longitudinal or through thickness direction. The thermal history and thermal properties of thermoplastic/CF composites were studied by longitudinal and through-thickness resistance measurements. The resistance results were consistent with differential scanning calorimetry (DSC) and thermomechanical analysis (TMA) results. The resistance measurements gave more information on the melting of the polymer matrix than TMA. They were more sensitive to the glass transition of the polymer matrix than DSC. The through-thickness resistance decreased as autohesion progressed. The activation energy of autohesion was 21.2 kJ/mol for both nylon-6 and polyphenylene sulfide (PPS)/CF composites. Adhesive bonding and debonding were monitored in real-time by measurement of the through-thickness resistance between the adherends in an adhesive joint during heating and subsequent cooling. Debonding occurred during cooling when the pressure or temperature during prior bonding was not sufficiently high. A long heating time below the melting temperature (T m) was found to be detrimental to subsequent PPS adhesive joint development above Tm, due to curing reactions below Tm and consequent reduced mass flow response above Tm. A high heating rate (small heating time) enhanced the bonding more than a high pressure. The longitudinal resistance measurement was used to investigate the effects of temperature and stress on the interface between a concrete substrate and its epoxy/CF composite retrofit. The resistance of the retrofit was increased by bond degradation, whether the degradation was due to heat or stress. The degradation was reversible. Irreversible disturbance in the fiber arrangement occurred slightly as thermal or load cycling occurred, as indicated by the

  18. DOE Fundamentals Handbook: Electrical Science, Volume 2

    SciTech Connect

    Not Available

    1992-06-01

    The Electrical Science Fundamentals Handbook was developed to assist nuclear facility operating contractors provide operators, maintenance personnel, and the technical staff with the necessary fundamentals training to ensure a basic understanding terminology, and application. The handbook includes information on alternating current (AC) and direct current (DC) theory, circuits, motors, and generators; AC power and reactive components; batteries; AC and DC voltage regulators; transformers; and electrical test instruments and measuring devices. This information will provide personnel with a foundation for understanding the basic operation of various types of DOE nuclear facility electrical equipment.

  19. Piezo-sensor self-diagnostics using electrical impedance measurements.

    SciTech Connect

    Park, G. H.; Farrar, C. R.; Rutherford, A. C.; Robertson, A. N.

    2004-01-01

    This paper present the piezoelectric sensor self-diagnostic procedure that performs in-situ monitoring of the operational status of piezoelectric materials (PZT) used for sensors and actuators in structural health monitoring (SHM) applications. The use of active-sensing piezoelectric materials has received considerable attention in the SHM community. A critical aspect of the piezoelectric active-sensing technologies is that usually large numbers of distributed sensors and actuators are needed to perform the required monitoring process. The sensor/actuator self-diagnostic procedure, where the sensors/actuators are confirmed to be functioning properly during operation, is therefore a critical component to successfully complete the SHM process and to minimize the false indication regarding the structural health. The basis of this procedure is to track the changes in the capacitive value of piezoelectric materials resulting from the sensor failure, which is manifested in the imaginary part of the measured electrical admittances. Furthermore, through the analytical and experimental investigation, it is confirmed that the bonding layer between the PZT and a host structure significantly contributes to the measured capacitive values. Therefore, by monitoring the imaginary part of the admittances, one can quantitatively assess the degradation of the mechanical/electrical properties of the PZT and its attachment to a host structure. This paper concludes with an experimental example to demonstrate the feasibility of the proposed sensor-diagnostic procedure.

  20. In-Vivo Electrical Impedance Measurement in Mastoid Bone.

    PubMed

    Wyss Balmer, Thomas; Ansó, Juan; Muntane, Enric; Gavaghan, Kate; Weber, Stefan; Stahel, Andreas; Büchler, Philippe

    2017-04-01

    Nerve monitoring is a safety mechanism to detect the proximity between surgical instruments and important nerves during surgical bone preparation. In temporal bone, this technique is highly specific and sensitive at distances below 0.1 mm, but remains unreliable for distances above this threshold. A deeper understanding of the patient-specific bone electric properties is required to improve this range of detection. A sheep animal model has been used to characterize bone properties in vivo. Impedance measurements have been performed at low frequencies (<1 kHz) between two electrodes placed inside holes drilled into the sheep mastoid bone. An electric circuit composed of a resistor and a Fricke constant phase element was able to accurately describe the experimental measurements. Bone resistivity was shown to be linearly dependent on the inter-electrode distance and the local bone density. Based on this model, the amount of bone material between the electrodes could be predicted with an error of 0.7 mm. Our results indicate that bone could be described as an ideal resistor while the electrochemical processes at the electrode-tissue interface are characterized by a constant phase element. These results should help increasing the safety of surgical drilling procedures by better predicting the distance to critical nerve structures.

  1. Electric Quadrupole Transition Measurements of Hydrogen Molecule with High Precision

    NASA Astrophysics Data System (ADS)

    Cheng, Cun-Feng; Wang, Jin; Tan, Yan; Liu, An-Wen; Hu, Shui-Ming

    2013-06-01

    Molecular hydrogen is the most fundamental, and the only neutral molecule expected to be both calculated and measured with extremely high accuracy. High-precision measurements of its spectroscopy, especially the levels at the electric ground state, play an important role in the examination of precise quantum chemistry calculations and some fundamental physical constants. In the infrared region, H_2, being a homonuclear diatomic molecule, only has very weak electric quadrupole transitions. We established a new spectroscopy approach with ultra-high precision and sensitivity as well, based on a laser-locked cavity ring-down spectrometer. An equivalent absorption path-length of thousands of kilometers and a frequency precision of 10^{-5} cm^{-1} have been achieved. Ro-vibrational spectra of the second overtone of H_2 have been recorded. The obtained results will provide a direct examination of the high-accuracy quantum theory. It also shades light on the determination of fundamental physical constants such as the electron/proton mass ratio in a molecular system.

  2. Performance evaluation of RF electric and magnetic field measuring instruments

    NASA Astrophysics Data System (ADS)

    Nesmith, B. C. W.; Ruggers, P. S.

    1982-03-01

    The need to quantify the electromagnetic fields emitted by industrial, scientific, or medical (ISM) products operating in the 10 to 300 MHs region requires the testing of instrumentation suitable for use in RF radiation hazard surveys. To meet this requirement, several procedures were devised to test the accuracy of the RF survey instrumentation. Measurement systems and protocols were developed and evaluated. The electric (E) an magnetic (H) field measuring instruments were tested for linearity, calibration accuracy, amplitude modulation response, directivity, antenna patterns, temperature response, drift and noise, radiofrequency interference and polarization response. Tests were performed on three commercially available RF survey instruments and a one-of-a-kind device over the 10 to 100 MHs region. Complete tests were only performed at the ISM frequency of 27.12 MHs. Errors for each of the tests are presented in tabular form.

  3. Property and microstructural nonuniformity in the yttrium-barium-copper-oxide superconductor determined from electrical, magnetic, and ultrasonic measurements. Ph.D. Thesis - Case Western Reserve Univ.

    NASA Technical Reports Server (NTRS)

    Roth, Don J.

    1991-01-01

    The purpose of this dissertation was the following: (1) to characterize the effect of pore fraction on a comprehensive set of electrical and magnetic properties for the yttrium-barium-copper-oxide (YBCO) high temperature ceramic superconductor; and (2) to determine the viability of using a room-temperature, nondestructive characterization method to aid in the prediction of superconducting (cryogenic) properties. The latter involved correlating ultrasonic velocity measurements at room temperature with property-affecting pore fraction and oxygen content variations. The use of ultrasonic velocity for estimating pore fraction in YBCO is presented, and other polycrystalline materials are reviewed, modeled, and statistically analyzed. This provides the basis for using ultrasonic velocity to interrogate microstructure. The effect of pore fraction (0.10-0.25) on superconductor properties of YBCO samples was characterized. Spatial (within-sample) variations in microstructure and superconductor properties were investigated, and the effect of oxygen content on elastic behavior was examined. Experimental methods used included a.c. susceptibility, electrical, and ultrasonic velocity measurements. Superconductor properties measured included transition temperature, magnetic transition width, transport and magnetic critical current density, magnetic shielding, a.c. loss, and sharpness of the voltage-current characteristics. An ultrasonic velocity image constructed from measurements at 1mm increments across a YBCO sample revealed microstructural variations that correlated with variations in magnetic shielding and a.c. loss behavior. Destructive examination using quantitative image analysis revealed pore fraction to be the varying microstructural feature.

  4. In vivo measurements of electrical conductivity of porcine organs at low frequency: new method of measurement.

    PubMed

    Spottorno, J; Multigner, M; Rivero, G; Alvarez, L; de la Venta, J; Santos, M

    2012-10-01

    Calculations of the induced currents created in the human body by external electromagnetic fields would be more accurate provided that more realistic experimental values of the electrical properties of the body were available. The purpose of this work is to experimentally obtain values for the conductivity of living organs in conditions close to the real situation. Two-electrode in vivo measurements of the bioimpedance of some porcine organs have been performed. From these measurements and taking into account geometrical considerations, the electrical conductivity for the kidney, liver, heart, and spinal cord has been obtained and were found to be higher than the values reported in the literature. Furthermore, a new experimental procedure is proposed where the conductivity is determined from the values of the electrical potential and currents that are induced by an external electromagnetic field created by a coil placed close to the organ under study.

  5. Evaluation of the electrode performance for PAFC by using acid absorption, acceleration and ac-impedance measurement

    SciTech Connect

    Kim, Chang-Soo; Song, Rak-Hyun; Choi, Byung-Woo

    1996-12-31

    In PAFC, the degradation on cathode electrode caused by carbon corrosion, platinum dissolution and growth is especially severe. An acceleration test is a good technique for evaluating the degradation of electrode performance, because it does not need long time. Coleman et al used thermal cycling and on-off cycling as an acceleration test. Song et al showed that hydrogen shortage decreased the electrode performance more rapidly than that of air shortage in gas shortage test. Honji et al reported that the rate of coarsening of Pt particle is rapid in open circuit potential and this is one of major causes on the performance degradation of electrode. The cathode performance has been studied by using acid absorption, acceleration and ac-impedance measurements as functions of the polytetrafluoroethylene (PTFE) contents and sintering temperatures of the electrode.

  6. Electrical Conductivity Measurements in Strongly Coupled Metal Plasmas

    NASA Astrophysics Data System (ADS)

    Desilva, Alan; Katsouros, Joseph

    1999-11-01

    We measure the electrical conductivity of strongly coupled plasmas of various metals, including aluminum, iron, copper, and tungsten, in the temperature range 6-30 kK, in a density range from about 1/2 solid density down to about 10-3 times solid density. These plasmas may have coupling parameters (ratio of mean interparticle Coulomb energy to mean kinetic energy) ranging from as high as 50 down to unity. Plasmas are created by rapid vaporization of metal wire in a water bath which act as a tamper. Streak photography serves to determine the growth of the plasma radius in time, allowing determination of mean density. Temperature is deduced from the measured energy input in conjunction with an equation of state from the LANL SESAME database [1], and a brightness temperature may be obtained from radiation measurements. The column resistance is determined from time-resolved voltage and current measurements. Results of conductivity measurements will be shown and compared with the predictions of conductivity theories. 1.SESAME: The Los Alamos National Laboratory Equation of State Database, Report LA-UR-92-3407, ed. S. P. Lyon and J. D. Johnson, Group T-1.

  7. New Experiment to Measure the Electron Electric Dipole Moment

    NASA Technical Reports Server (NTRS)

    Kittle, Melanie

    2003-01-01

    An electron can possess an electric dipole moment (edm) only if time reversal symmetry (T) is violated. No edm of any particle has yet been discovered. CP-violation, equivalent to T-violation by the CPT theorem, does occur in Kaon decays and can be accounted for by the standard model. However, this mechanism leads to an electron edm d(sub e) of the order of 10(exp -38) e cm, whereas the current experimental bound on d(sub e) is about 10(exp -27) e cm. However, well-motivated extensions of the standard model such as supersymmetric theories do predict that de could be as large as the current bound. In addition, CP violation in the early universe is required to explain the preponderance of matter over anti-matter, but the exact mechanism of this CP violation is unclear. For these reasons, we are undertaking a new experimental program to determine de to an improved accuracy of 10(exp -29) e cm. Our experiment will use laser-cooled, trapped Cesium atoms to measure the atomic edm d(sub Cs) that occurs if d(sub e) is not zero. In order to do this, we will measure the energy splitting between the atoms spin states in parallel electric and magnetic fields. The signature of an edm would be a linear dependence of the splitting on the electric field E due to the interaction - d(sub Cs) dot E. Our measurement will be much more sensitive than previous measurements because atoms can be stored in the trap for tens of seconds, allowing for much narrower Zeeman resonance linewidths. Also, our method eliminates the most important systematic errors, proportional to atomic velocity, which have limited previous experiments. In this presentation, we will describe the design of our new apparatus, which is presently under construction. An important feature of our experimental apparatus is that magnetic field noise will be suppressed to a very low value of the order of 1 fT/(Hz)1/2. This requires careful attention to the Johnson noise currents in the chamber, which have not been important

  8. Electrical, dielectric and electrochemical measurements of bulk aluminum phthalocyanine chloride (AlPcCl)

    NASA Astrophysics Data System (ADS)

    Soliman, I. M.; El-Nahass, M. M.; Mansour, Y.

    2016-01-01

    AC conductivity and the related dielectric properties of bulk aluminum phthalocyanine chloride (AlPcCl) have been studied over a temperature range (303-403 K) and frequency range (42-106 Hz). The universal power law σac (ω)=Aωs has been used to investigate dependence of AC conductivity on frequency. The variation of the frequency exponent (s) with temperature was analyzed in terms of different conduction mechanisms; the predominant conduction mechanism was found to be the correlated barrier hopping (CBH) model. The barrier height was calculated by using (CBH) model, it was found to be 1.41 eV. Dependence of σac (ω) on temperature refers to a linear increase with increasing temperature at different frequencies. The density of states N (EF) was calculated to be equal 4.11×1019 cm-3 using Elliott model. It has been found that AC activation energy decreases with increasing frequency. Dielectric values were analyzed using complex permittivity and complex electric modulus for bulk AlPcCl at different temperatures. The obtained value of HOMO-LUMO energy gap was found to be 1.48 eV.

  9. Modelling Electrostatic Sheath Effects on Swarm Electric Field Instrument Measurements

    NASA Astrophysics Data System (ADS)

    Marchand, R.; Burchill, J. K.; Knudsen, D. J.

    2010-10-01

    The Electric Field Instrument (EFI) was designed to measure ionospheric ion flow velocities, temperatures and distribution functions at the ram face of the European Space Agency’s Swarm spacecraft. These flow velocities, combined with the known orbital velocity of the satellite and local magnetic field, will be used to infer local electric fields from the relation E=- v× B. EFI is among a class of many particle sensors and flow meters mounted on satellites to monitor in situ plasma conditions. The interpretation of the measurements made with EFI and similar sensors relies on a spacecraft sheath model. A common approach, valid in the relatively cold and dense ionospheric plasma, is to assume a potential drop in a thin sheath through which particle deflection and energisation can be calculated analytically. In such models, sheath effects only depend on the spacecraft floating potential, and on the angle of incidence of particles with respect to the normal to the surface. Corrections to measurements are therefore local as they do not depend on the geometry of nearby objects. In an actual plasma, satellites are surrounded by electrostatic sheaths with a finite thickness. As a result, local corrections to particle distribution functions can only be seen as an approximation. A correct interpretation of measured particle fluxes or particle distribution functions must, at least in principle, account for the extent and shape of the sheath in the vicinity of the measuring instrument. This in turn requires a careful analysis of the interaction of the satellite with the surrounding plasma, while accounting for detailed aspects of the geometry, as well as for several physical effects. In this paper, the validity of the thin sheath model is tested by comparing its predictions with detailed PIC (Particle In Cell) calculations of satellite-plasma interaction. Deviations attributed to sheath finite thickness effects are calculated for EFI measurements, with representative plasma

  10. Dynamic characteristics of double-barrier nanostructures with asymmetric barriers of finite height and widths in a strong ac electric field

    SciTech Connect

    Chuenkov, V. A.

    2013-12-15

    The theory of the interaction of a monoenergetic flow of injected electrons with a strong high-frequency ac electric field in resonant-tunneling diode (RTD) structures with asymmetric barriers of finite height and width is generalized. In the quasi-classical approximation, electron wavefunctions and tunneling functions in the quantum well and barriers are found. Analytical expressions for polarization currents in RTDs are derived in both the general case and in a number of limiting cases. It is shown that the polarization currents and radiation power in RTDs with asymmetric barriers strongly depend on the ratio of the probabilities of electron tunneling through the emitter and collector barriers. In the quantum mode, when δ = ε − ε{sub r} = ħω ≪ Γ (ε is the energy of electrons injected in the RTD, ħ is Planck’s constant, ω is the ac field frequency, ε{sub r} and Γ are the energy and width of the resonance level, respectively), the active polarization current in a field of E ≈ 2.8ħω/ea (e is the electron charge and a is the quantum-well width) reaches a maximum equal in magnitude to 84% of the direct resonant current, if the probability of electron tunneling through the emitter barrier is much higher than that through the collector barrier. The radiation-generation power at frequencies of ω = 10{sup 12}–10{sup 13} s{sup −1} can reach 10{sup 5}–10{sup 6} W/cm{sup 2} in this case.

  11. Effect of borehole design on electrical impedance tomography measurements

    NASA Astrophysics Data System (ADS)

    Mozaffari, Amirpasha; Huisman, Johan Alexander; Treichel, Andrea; Zimmermann, Egon; Kelter, Matthias; Vereecken, Harry

    2015-04-01

    Electrical Impedance Tomography (EIT) is a sophisticated non-invasive tool to investigate the subsurface in engineering and environmental studies. To increase the depth of investigation, EIT measurements can be made in boreholes. However, the presence of the borehole may affect EIT measurements. Here, we aim to investigate the effect of different borehole components on EIT measurements using 2,5-D and 3D finite element modeling and unstructured meshes. To investigate the effect of different borehole components on EIT measurements, a variety of scenarios were designed. In particular, the effect of the water-filled borehole, the PVC casing, and the gravel filter were investigated relative to complex resistivity simulations for a homogenous medium with chain and electrode modules. It was found that the results of the complex resistivity simulations were best understood using the sensitivity distribution of the electrode configuration under consideration. In all simulations, the sensitivity in the vicinity of the borehole was predominantly negative. Therefore, the introduction of the water-filled borehole caused an increase in the real part of the impedance, and a decrease (more negative) in the imaginary part of the simulated impedance. The PVC casing mostly enhanced the effect of the water-filled borehole described above, although this effect was less clear for some electrode configuration. The effect of the gravel filter mostly reduced the effect of the water-filled borehole with PVC casing. For EIT measurements in a single borehole, the highest simulated phase error was 12% for a Wenner configuration with electrode spacing of 0.33 m. This error decreased with increasing electrode spacing. In the case of cross-well configurations, the error in the phase shit was as high as 6%. Here, it was found that the highest errors occur when both current electrodes are located in the same borehole. These results indicated that cross-well measurements are less affected by the

  12. Measurement strategy for rectangular electrical capacitance tomography sensor

    SciTech Connect

    Ye, Jiamin; Ge, Ruihuan; Qiu, Guizhi; Wang, Haigang

    2014-04-11

    To investigate the influence of the measurement strategy for the rectangular electrical capacitance tomography (ECT) sensor, a Finite Element Method (FEM) is utilized to create the model for simulation. The simulation was carried out using COMSOL Multiphysics(trade mark, serif) and Matlab(trade mark, serif). The length-width ratio of the rectangular sensing area is 5. Twelve electrodes are evenly arranged surrounding the pipe. The covering ratio of the electrodes is 90%. The capacitances between different electrode pairs are calculated for a bar distribution. The air of the relative permittivity 1.0 and the material of the permittivity 3.0 are used for the calibration. The relative permittivity of the second phase is 3.0. The noise free and noise data are used for the image reconstruction using the Linear Back Projection (LBP). The measurement strategies with 1-, 2- and 4- electrode excitation are compared using the correlation coefficient. Preliminary results show that the measurement strategy with 2-electrode excitation outperforms other measurement strategies with 1- or 4-electrode excitation.

  13. Experimental and theoretical study of AC electrical conduction mechanisms of Organic-inorganic hybrid compound Bis (4-acetylanilinium) tetrachlorocadmiate (II)

    NASA Astrophysics Data System (ADS)

    Jellibi, A.; Chaabane, I.; Guidara, K.

    2016-06-01

    A new organic-inorganic bis (4-acetylaniline) tetrachlorocadmate [C8H10NO]2[CdCl4] can be obtained by slow evaporation at room temperature and characterized by X-ray powder diffraction. It crystallized in an orthorhombic system (Cmca space group). The material electrical properties were characterized by impedance spectroscopy technique in the frequency range from 209 Hz-5 MHz and temperature 413 to 460 K. Besides, the impedance plots show semicircle arcs at different temperatures and an electrical equivalent circuit has been proposed to interpret the impedance results. The circuits consist of the parallel combination of a resistance (R), capacitance (C) and fractal capacitance (CPE). The variation of the exponent s as a function of temperature suggested that the conduction mechanism in Bis (4-acetylanilinium) tetrachlorocadmiate compound is governed by two processes which can be ascribed to a hopping transport mechanism: correlated barrier hopping (CBH) model below 443 K and the small polaron tunneling (SPT) model above 443 K.

  14. DNA sequencing using electrical conductance measurements of a DNA polymerase

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Shiun; Lee, Chia-Hui; Hung, Meng-Yen; Pan, Hsu-An; Chiou, Jin-Chern; Huang, G. Steven

    2013-06-01

    The development of personalized medicine--in which medical treatment is customized to an individual on the basis of genetic information--requires techniques that can sequence DNA quickly and cheaply. Single-molecule sequencing technologies, such as nanopores, can potentially be used to sequence long strands of DNA without labels or amplification, but a viable technique has yet to be established. Here, we show that single DNA molecules can be sequenced by monitoring the electrical conductance of a phi29 DNA polymerase as it incorporates unlabelled nucleotides into a template strand of DNA. The conductance of the polymerase is measured by attaching it to a protein transistor that consists of an antibody molecule (immunoglobulin G) bound to two gold nanoparticles, which are in turn connected to source and drain electrodes. The electrical conductance of the DNA polymerase exhibits well-separated plateaux that are ~3 pA in height. Each plateau corresponds to an individual base and is formed at a rate of ~22 nucleotides per second. Additional spikes appear on top of the plateaux and can be used to discriminate between the four different nucleotides. We also show that the sequencing platform works with a variety of DNA polymerases and can sequence difficult templates such as homopolymers.

  15. Investigation of microflow reversal by ac electrokinetics in orthogonal electrodes for micropump design.

    PubMed

    Yang, Kai; Wu, Jie

    2008-04-04

    Orthogonal electrodes have been reported to produce high velocity microflows when excited by ac signals, showing potential for micropumping applications. This paper investigates the microflow reversal phenomena in such orthogonal electrode micropumps. Three types of microflow fields were observed by changing the applied electric signals. Three ac electrokinetic processes, capacitive electrode polarization, Faradaic polarization, and the ac electrothermal effect, are proposed to explain the different flow patterns, respectively. The hypotheses were corroborated by impedance analysis, numerical simulations, and velocity measurements. The investigation of microflow reversal can improve the understanding of ac electrokinetics and hence effectively manipulate fluids.

  16. Electric field and plasma density measurements in the auroral electrojet

    NASA Astrophysics Data System (ADS)

    Pfaff, R. F.; Kelley, M. C.; Fejer, B. G.; Kudeki, E.; Carlson, C. W.; Pedersen, A.; Hausler, B.

    1984-01-01

    Extensive experimental and theoretical studies of auroral and equatorial electrojet irregularities have been conducted for the last two decades. The present investigation is concerned with electric field and plasma density fluctuation measurements made on board of the Porcupine II sounding rocket and on a free-flyer ejected from the main spacecraft. The Porcupine II sounding rocket payload was launched at 1922:00 UT from Kiruna, Sweden, on March 20, 1977. The considered results show electrostatic turbulence in the unstable auroral E region confined to a layer between 96 and 121 km. The similarities between the observations of two simultaneous payloads spaced a few kilometers apart indicate that on a large scale, the electrojet turbulence displays uniform characteristics.

  17. Structural and ac electrical properties of LiCoPO4 synthesised by template free hydrothermal approach

    NASA Astrophysics Data System (ADS)

    Vijayan, Lakshmi; Cheruku, Rajesh; Govindaraj, G.

    2013-02-01

    Olivine structured material shows specific capacities up to 170mAh/g and can be charged in a very short time. LiMPO4, (M=transition metal ion) does not consists of heavy metal and have no memory loss like Ni-Cd, Ni-metal hydride solutions. Benefit of LiMPO4 is its flexibility for the cell design and battery applications. Li based LiCoPO4 of Orthophosphate family is synthesized by template free sucrose assisted hydrothermal method. Olivine structured compounds possess orthorhombic crystal structure with Pnma, pmnb space group having four formula units. The material is characterized through different techniques like XRD, FTIR, SEM, VSM and electrical characterization is done through impedance spectroscopy and the results are reported.

  18. 77 FR 47043 - Work Group on Measuring Systems for Electric Vehicle Fueling

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-08-07

    ... National Institute of Standards and Technology Work Group on Measuring Systems for Electric Vehicle Fueling... residential and business locations and those used to measure and sell electricity dispensed as a vehicle fuel... devices and systems used to assess charges to consumers for electric vehicle fuel. There is no cost...

  19. In-process Measuring of Capacitance Per Unit Length for Single-core Electric Wires

    NASA Astrophysics Data System (ADS)

    Goldshtein, A. E.; Vavilova, G. V.; Mazikov, S. V.

    2016-01-01

    The paper describes technical in-process implementation of the electrical method to measure the electrical capacitance per unit length of a single core electric wire. The basic design values of the electro-capacitive measuring transducer are determined. The impact of changes in water conductivity on measurement results is analyzed. Techniques to offset from the impact of changes in water conductivity on the results of the electrical capacitance per unit length control based on indirect electrical conductivity measurement are considered. An appropriate correction of the conversion function is made.

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

    PubMed

    Zengin, Reyhan; Gençer, Nevzat Güneri

    2016-08-21

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

  1. Lorentz force electrical impedance tomography using magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Zengin, Reyhan; Güneri Gençer, Nevzat

    2016-08-01

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

  2. Electric Field Change Measurements of a Terrestrial Gamma Ray Flash

    NASA Astrophysics Data System (ADS)

    Marshall, Thomas; Karunarathne, Sumedhe; Stolzenburg, Maribeth

    2016-04-01

    Cummer et al. [GRL, 2014] reported on two terrestrial gamma ray flashes (TGFs) detected by the Gamma ray Burst Monitor (GBM) on the Fermi satellite. At a range of 632 km we detected an electric field change pulse associated with the first of these TGFs. The sensor bandwidth was 0.16 Hz - 2.6 MHz and was sampled at 5 MS/s. The measured zero-to-peak amplitude was 3.1 V/m. Assuming a 1/R range dependence, the amplitude range normalized to 100 km would be about 20 V/m. However, a little more than half of the path from the TGF to the sensor was over land rather than ocean, which should cause the attenuation to be greater than 1/R. Based on recent measurements of Kolmasova et al. (2015 AGU Fall Meeting), we estimate that the real peak amplitude was 40 - 50 V/m. The detected pulse was bipolar with a leading positive peak and had an overall duration of about 50 μs; these characteristics are typical of initial breakdown pulses (IBPs) that occur at the beginning of intracloud (IC) flashes. However, the pulse amplitude is an order of magnitude larger than typical IBPs. These data support the notion that IBPs of IC flashes cause TGFs [e.g., Shao et al., JGR 2010; Lu et al., GRL 2010; Cummer et al., GRL 2014].

  3. A three-dimensional measurement method for medical electric endoscope

    NASA Astrophysics Data System (ADS)

    Zhou, Tingting; Tao, Pei; Yuan, Bo; Wang, Liqiang

    2017-01-01

    One method for three-dimensional (3D) measurement based on structured light is proposed for the medical electric endoscope in the present study. The structured light of black and white strips is generated by that the point sources illuminate the grating mask plate. Four point sources are aligned linearly by a certain space and they are lighted sequentially. Then four images of modulated fringes by the height of object with different phase shifts can be obtained. The algorithm proposed by Wang Z is employed to extract the accurate phase shift from the fringe images since the phase shift cannot be exactly set as π/2 by hardware. An experimental prototype endoscope was built according to the proposed method. One high-definition CMOS camera module developed by ourselves was used to acquire the endoscopic images and the structured light was generated by four fiber LEDs and a transmission grating with a pitch of 0.1 mm. one C# program was designed to light up LEDs in turn, acquire the phase shifted images and calculate the 3D information. The experimental results indicate that its precise of depth measurement at the working distance of 40 mm is better than 0.5 mm and its consuming time of 3D depth calculation is less than 0.5 s.

  4. Influence of Dopants on Electrical Properties of ZnO-V2O5 Varistors Deduced from AC Impedance and Variable-Temperature Dielectric Spectroscopy

    NASA Astrophysics Data System (ADS)

    Wu, Jun; Li, Taotao; Qi, Ting; Qin, Qingwei; Li, Guangqiang; Zhu, Bailin; Wu, Run; Xie, Changsheng

    2012-07-01

    The influence of MnO2, PbO, and a mixture of MnO2, PbO, and B2O3 on the electrical and dielectric properties of ZnO-V2O5 ceramics was studied by alternating-current (AC) impedance and variable-temperature dielectric spectroscopy. The results show that, compared with the resistivity of the intervening layer at the grain boundary, the Schottky barrier present at the grain boundary is much more important for varistor performance, which can be significantly improved by using a mixture of MnO2, PbO, and B2O3. Consequently, better varistor performance is achieved for 94.5 mol.% ZnO + 0.5 mol.% V2O5 + 1.0 mol.% MnO2 + 2.0 mol.% PbO + 2.0 mol.% B2O3 (ZVMPB), i.e., nonlinear coefficient α = 35.3 and leakage current density I l = 2.72 μA/cm2. The activation energy for the characteristic dielectric relaxation process is in the range of 0.339 eV to 0.365 eV, indicating that it is only associated with oxygen vacancy V{O/·}.

  5. Influence of temperature on the electric, dielectric and AC conductivity properties of nano-crystalline zinc substituted cobalt ferrite synthesized by solution combustion technique

    NASA Astrophysics Data System (ADS)

    Rani, Ritu; Kumar, Gagan; Batoo, Khalid M.; Singh, M.

    2014-06-01

    Cobalt-zinc nanoferrites with formulae Co ZnFeO, where x = 0.0, 0.1, 0.2 and 0.3, have been synthesized by solution combustion technique. The variation of DC resistivity with temperature shows the semiconducting behavior of all nanoferrites. The dielectric properties such as dielectric constant (') and dielectric loss tangent (tan are investigated as a function of temperature and frequency. Dielectric constant and loss tangent are found to be increasing with an increase in temperature while with an increase in frequency both, ' and tan , are found to be decreasing. The dielectric properties have been explained on the basis of space charge polarization according to Maxwell-Wagner's two-layer model and the hopping of charge between Fe and Fe. Further, a very high value of dielectric constant and a low value of tan are the prime achievements of the present work. The AC electrical conductivity ( is studied as a function of temperature as well as frequency and is observed to be increasing with the increase in temperature and frequency.

  6. AC heat capacities of κ-(BEDT-TTF)2Cu2(CN)3 measured by microchip calorimeter

    NASA Astrophysics Data System (ADS)

    Muraoka, Y.; Yamashita, S.; Yamamoto, T.; Nakazawa, Y.

    2011-09-01

    Thermodynamic measurements of an organic spin liquid compound of κ-(BEDT-TTF)2Cu2(CN)3 where BEDT-TTF is bis(ethylenedithio)tetrathiafulvalene were performed by the ac calorimetry technique using a microchip device of TCG3880. This technique is effective to measure relative temperature and magnetic-field dependences of heat capacity for tiny single crystal samples less than 1μg. Broad hump structures in Cp vs T which are known as so-called 6 K anomaly were observed in κ-(BEDT-TTF)2Cu2(CN)3 and its deuterated compound. The hump temperatures are evaluated as 5.7 K in both compounds. This result demonstrates that the TCG3880 is useful for performing thermodynamic investigations of such kind of organic charge transfer complexes with much reduced sample quantity than the conventional techniques and that the existence of hump structure is intrinsic for κ-(BEDT-TTF)2Cu2(CN)3. The in-plane angular dependence of the magnetic field of 7 T applied parallel to the two dimensional layer is also studied and absence of in-plane anisotropy of the hump structure is discussed in both pristine and deuterated compounds.

  7. Estimation of Density of Localized States in Amorphous Se80Te20 and Se80Te10M10 (M = Cd, In, Sb) Alloys Using AC Conductivity Measurements

    NASA Astrophysics Data System (ADS)

    Chandel, N.; Mehta, N.; Kumar, A.

    2015-08-01

    The ac conductivity of amorphous Se80Te20 (a-Se80Te20) and amorphous Se80Te10M10 (a-Se80Te10M10) alloys has been measured as a function of temperature and frequency in a low-temperature regime. An analysis of the experimental data confirms that ac conductivity is reasonably well interpreted by the Austin-Mott model. The density of localized states was determined in the low-temperature region from 201 K to 280 K. Possible explanations of "metal-induced effects" on the conduction mechanism of a-Se80Te20 alloy are discussed.

  8. A single-shot spatial chirp method for measuring initial AC conductivity evolution of femtosecond laser pulse excited warm dense matter

    SciTech Connect

    Chen, Z.; Hering, P.; Brown, S. B.; Curry, C.; Tsui, Y. Y.; Glenzer, S. H.

    2016-09-19

    To study the rapid evolution of AC conductivity from ultrafast laser excited warm dense matter (WDM), a spatial chirp single-shot method is developed utilizing a crossing angle pump-probe configuration. The pump beam is shaped individually in two spatial dimensions so that it can provide both sufficient laser intensity to excite the material to warm dense matter state and a uniform time window of up to 1 ps with sub-100 fs FWHM temporal resolution. Here, temporal evolution of AC conductivity in laser excited warm dense gold was also measured.

  9. A single-shot spatial chirp method for measuring initial AC conductivity evolution of femtosecond laser pulse excited warm dense matter.

    PubMed

    Chen, Z; Hering, P; Brown, S B; Curry, C; Tsui, Y Y; Glenzer, S H

    2016-11-01

    To study the rapid evolution of AC conductivity from ultrafast laser excited warm dense matter (WDM), a spatial chirp single-shot method is developed utilizing a crossing angle pump-probe configuration. The pump beam is shaped individually in two spatial dimensions so that it can provide both sufficient laser intensity to excite the material to warm dense matter state and a uniform time window of up to 1 ps with sub-100 fs FWHM temporal resolution. Temporal evolution of AC conductivity in laser excited warm dense gold was also measured.

  10. Electrical conductivity and Equation of State from Measurements of a Tamped Electrically Exploded Foil

    NASA Astrophysics Data System (ADS)

    Ruden, Edward; Amdahl, David; Cooksey, Rufus; Domonkos, Matthew; Robinson, Paul; Analla, Francis; Brown, Darwin; Kostora, Mark; Camacho, Frank

    2013-10-01

    Results are presented for an experiment that produces and diagnoses dynamic surface conditions of homogeneous warm dense matter (WDM) to infer intrinsic bulk properties such as density, pressure, temperature, specific energy, electrical conductivity, and emissivity in the ranges of up to few eV and down to 0.1 solid density-typical of those encountered in single shot pulsed power device electrodes. The goal is to validate ab initio models of matter encountered for predictive modeling of such devices. In the test whose results are presented here, the WDM is produced by Ohmically heating and exploding an 80 μm Al foil placed between two fused quartz tampers by the discharge of a 36 μF capacitor bank charged to 30.1 kV and discharged in 2.55 μs to a peak load current of 460 kA. Measurements are presented from two division of amplitude polarimeters which operate at 532 nm and 1064 nm, a complementary pyrometer which measures the spectral radiance ratio at those wavelengths, a long-range 660 nm photonic Doppler velocimeter, and a B-dot probe array from which the aforementioned intrinsic properties may be inferred. Available results are compared to a 3-D MHD ALEGRA simulation of the full dynamic load and return conductor geometry with a two-loop external coupled circuit.

  11. Electrical Conductivity Measurements in Strongly Coupled Metal Plasmas

    NASA Astrophysics Data System (ADS)

    Desilva, Alan

    1998-11-01

    The coupling parameter Γ=e^2/akT, where a is the mean ion-ion separation, expresses the ratio of the mean potential energy of ions in a plasma to their mean kinetic energy. Plasma is said to be strongly coupled when Γ is greater than unity. Transport properties of strongly coupled plasmas are of interest in the study of the structure of dense astrophysical objects and gaseous planetary interiors, as well as in arcs and laser-produced plasmas. We are attempting to measure the electrical conductivity of strongly coupled metal plasmas (copper, tungsten and aluminum) in the temperature range 8-30 kK, in a density range from about 1/2 solid density down to about 10-3 times solid density. They may have coupling parameters Γ ranging from as high as 100 down to unity Plasmas are created by rapid vaporization of metal wire in a glass capillary or in a water bath which act as a tamper, slowing the expansion rate. The effect of the tamper is to force the interior pressure of the plasma to be fairly uniform. Streak photography serves to determine the growth of the plasma radius in time, allowing determination of mean density. Temperature is deduced from the measured energy input in conjunction with an equation of state from the LANL sesame database(SESAME: The Los Alamos National Laboratory Equation of State Database, Report No. LA-UR-92-3407, Ed. S. P. Lyon and J. D. Johnson, Group T-1 (unpublished)), and a brightness temperature may be obtained from radiation measurements. The column resistance is simply determined from time-resolved voltage and current measurements. For temperatures less than about 14,000K, as density decreases from the highest values measured, the conductivity falls roughly as the cube of density, reaches a minimum, and subsequently rises to approach the Spitzer prediction at low density. The rate of change of conductivity with density becomes less rapid as temperature increases, and the minimum becomes less pronounced, disappearing altogether above

  12. Early results from ISEE-A electric field measurements

    NASA Technical Reports Server (NTRS)

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

    1978-01-01

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

  13. Fiber optical measurements of electrical activity in canine ventricular preparations

    NASA Astrophysics Data System (ADS)

    Squires, Amgad; Luther, Gisa E.; Enyeart, Michael; Gilmour, Robert F.; Bodenschatz, Eberhard; Luther, Stefan

    2006-03-01

    Ventricular fibrillation (VF) is a cardiac arrhythmia that kills over 300,000 people every year in the US alone, yet efforts at finding a cure have been stymied by our incomplete information about patterns of electrical activity in the whole heart. As an excitable medium, the heart is a pattern forming system; but only a very limited subset of patterns is compatible with life. In particular, spiral waves have been associated with both tachycardia and VF, but their origin and spatial and temporal dynamics is not fully understood. We propose a novel measurement technique that combines optical mapping of the epicardial surface with data from intramural fiber optical probe arrays. The data obtained from the fiber optical probes is sparse in space but dense in time. The data processing is based on sequential data assimilation using an ensemble Kalman filter. The ensemble Kalman filter provides a numerically efficient (sub-) optimum state space estimate based on the available spatial and temporal observations. The feasibility of the method is demonstrated with numerical data and arterially perfused canine heart preparations.

  14. Electric-field-vector measurement in a glow discharge

    SciTech Connect

    Ganguly, B.N.; Garscadden, A.

    1985-10-01

    The magnetic quantum number selection rule implies that radiation that is linearly polarized perpendicular to the electric field will not excite ..delta..m = 0 transitions. This phenomenon in Stark spectra has been used to determine the electric field vector in a positive column dc discharge in helium. The technique is applicable to both linear and nonlinear Stark effects.

  15. Prospects for electric-dipole-moment measurements in radon

    NASA Astrophysics Data System (ADS)

    Chupp, Timothy

    2014-09-01

    A permanent electric dipole moment (EDM) of a particle or system would arise due to breaking of time-reversal, or equivalently CP symmetry. Experiments to date on the neutron, atoms and molecules have only set upper limits on EDMs. New techniques and systems in which the effects of CP violation would be greatly enhanced are driving the field forward. Systems that may be favorable for significant advances include 221,223Rn, where the combination of octupole collectivity and relatively closely spaced opposite parity levels would increase the nuclear Schiff moment by one or more orders of magnitude compared to other diamagnetic atoms, i.e. 199Hg. We have developed and tested at TRIUMF-ISAC an on-line EDM experiment that will collect and make measurements on the short-lived species (T1 / 2 ~ 25 m) featuring high-efficiency collection and spin-exchange polarization of noble-gas isotopes. Nuclear-structure issues include determining the octupole collectivity as well as the spacing of opposite parity levels. Experiments are underway at ISOLDE, NSCL and ISAC to study the nuclear structure of isotopes in this mass region. I will report on progress and comment on how we learn about the basic physical parameters of CP violation from EDM measurements. A permanent electric dipole moment (EDM) of a particle or system would arise due to breaking of time-reversal, or equivalently CP symmetry. Experiments to date on the neutron, atoms and molecules have only set upper limits on EDMs. New techniques and systems in which the effects of CP violation would be greatly enhanced are driving the field forward. Systems that may be favorable for significant advances include 221,223Rn, where the combination of octupole collectivity and relatively closely spaced opposite parity levels would increase the nuclear Schiff moment by one or more orders of magnitude compared to other diamagnetic atoms, i.e. 199Hg. We have developed and tested at TRIUMF-ISAC an on-line EDM experiment that will collect

  16. AC Losses of Prototype HTS Transmission Cables

    SciTech Connect

    Demko, J.A.; Dresner, L.; Hughey, R.L.; Lue, J.W.; Olsen, S.K.; Sinha, U.; Tolbert, J.C.

    1998-09-13

    Since 1995 Southwire Company and Oak Ridge National Laboratory (ORNL) have jointly designed, built, and tested nine, l-m long, high temperature superconducting (HTS) transmission cable prototypes. This paper summarizes the AC loss measurements of five of the cables not reported elsewhere, and compares the losses with each other and with theory developed by Dresner. Losses were measured with both a calorimetric and an electrical technique. Because of the broad resistive transition of the HTS tapes, the cables can be operated stably beyond their critical currents. The AC losses were measured in this region as well as below critical currents. Dresner's theory takes into account the broad resistive transition of the HTS tapes and calculates the AC losses both below and above the critical current. The two sets of AC 10SS data agree with each other and with the theory quite welL In particular, at low currents of incomplete penetration, the loss data agree with the theoretical prediction of hysteresis loss based on only the outer two Iayers carrying the total current.

  17. A simple AC calorimeter for specific heat measurement of liquids confined in porous materials: A study of hydrated Vycor

    NASA Astrophysics Data System (ADS)

    Bonetti, Marco; Zanotti, Jean-Marc

    2016-09-01

    Nanometric confinement of fluids in porous media is a classical way to stabilize metastable states. Calorimetric studies give insight on the behavior of confined liquids compared to bulk liquids. We have developed and built a simple quasi-adiabatic AC calorimeter for heat capacity measurement of confined liquids in porous media in a temperature range between 150 K and 360 K. Taking the fully hydrated porous medium as a reference, we address the thermal behavior of water as a monolayer on the surface of a porous silica glass (Vycor). For temperature ranging between 160 K and 325 K, this interfacial water shows a surprisingly large heat capacity. We describe the interfacial Hbond network in the framework of a mean field percolation model, to show that at 160 K interfacial water experiences a transformation from low density amorphous ice to a heterogeneous system where transient low and high density water patches coexist. The fraction of each species is controlled by the temperature. We identify the large entropy of the interfacial water molecules as the cause of this behaviour.

  18. Device and methods for the measurement of energy transfer in experiments involving thermal and electrical injuries of skin.

    PubMed

    Nielsen, K G; Nielsen, O; Thomsen, H K

    1981-01-01

    This work is part of a larger investigation aiming at tracing differences between injuries caused by heat and electricity. Electrodes and heaters similar to the electrodes of an electric cattle baton are used to dissipate approximately 40 joules in 40 seconds in pig skin. Voltages in the range 40-60 volts (AC or DC) are applied via stainless steel electrodes and temperatures in the range 50-100 degrees C are applied via heaters made of copper wire. Heat transfer is controlled by electronically regulated heaters utilizing the temperature dependence of the heater wire itself as a thermometer. Transfer of electricity takes place from either commercial DC supply, from transformed voltage from the mains or from a sine voltage generator connected to a power amplifier. The energy transfer is in all cases measured by electronic integration of the dissipated power in time. The power supplied to th electrodes or the heaters is found by electronic multiplication of the applied voltage and current. Typical power vs. time curves are presented.

  19. Evolution of AC conductivity of wet illitic clay during drying

    NASA Astrophysics Data System (ADS)

    Csáki, Š.; Štubňa, I.; Trnovcová, V.; Ondruška, J.; Vozár, L.; Dobroň, P.

    2017-02-01

    The evolution of the AC electrical conductivity during drying as well as the relationship between sample volume and moisture of green illite samples were investigated. The samples were prepared from illitic clay (80 mass % illite, 4 mass % montmorillonite, 12 mass % quartz and 4 mass % of orthoclase) and distilled water with initial moisture content 36 mass % and were freely dried in air. Conductivity was measured by the volt-ampere method with AC power supply of 5 V in the frequency range from 50 Hz to 10 kHz. The AC conductivity steeply increased with increasing moisture, up to 15 mass %. At higher values of the moisture, the AC conductivity was high and almost constant. The volume of samples increased with increasing moisture when the moisture was higher than 8 mass %. Below this value, the dimensions of samples do not significantly change. The dependence of the relative volume change on moisture is presented in a form of the Bigot’s curve.

  20. Measurement of DC Electric Field in the Midlatitude Ionosphere by S-520-23 Sounding Rocket Experiments

    NASA Astrophysics Data System (ADS)

    Ishisaka, K.; Yamamoto, M.; Yokoyama, T.; Watanabe, S.; Okada, T.; Abe, T.; Kumamoto, A.

    2014-12-01

    S-520-23 sounding rocket experiments are carried out at Uchinoura Space Center (USC) in Japan at 19:20 LT on 2 September, 2007. The purpose of this experiment is the investigation of the process of momentum transportation between the atmospheres and the plasma in the thermosphere during the summer evening time at mid latitudes. The S-520-23 payload was equipped with a two set of orthogonal double probes to measure both DC and AC less than 40Hz electric fields in the spin plane of the payload. One of the double probe is the inflatable structure antenna, called the SPINAR, with a length of 5m tip-to-tip. The SPINAR was the first successful use of an inflatable structure as a flight antenna. It extended and worked without any problems. Another one is the NEI type antenna with a length of 2m tip-to-tip. The electrodes of two double probe antennas were used to gather the potentials which were detected with high impedance pre-amplifiers using the floating (unbiased) double probe technique. The potential differences on the two main orthogonal axes were digitized on-board using 16-bit analog-digital converters, sampled at 400 samples/sec with low pass filters at cut-off frequency of 40Hz. We have investigated the DC electric field during the rocket ascent. And it was able to obtain the electric field vector in a geographic-coordinates system. The direction of DC electric field vector at altitude from 140km to 170km is seems to be dependent on the direction of a neutral wind in the ionosphere. And intensity of DC electric field is increasing at altitude more than 260km. Its direction is east. It is thought that the polarization electric field was observed in the region where the difference of the electron density was large after sunset. In this presentation, we will describe the result of investigation of the relationship between an electric field and ionospheric plasma in detail. Especially the dependence of the direction of electric field and the direction of the neutral

  1. Non-Contact Measurement of the Electrical Impedance of Biological Tissue

    DTIC Science & Technology

    2007-11-02

    NON-CONTACT MEASUREMENT OF THE ELECTRICAL IMPEDANCE OF BIOLOGICAL TISSUE C.H. Riedel and O.Dössel Institute of Biomedical Engineering, Universität...currents. Keywords—contact-free measurement, electrical im- pedance, coil systems I. Introduction The non-invasive method of measuring the impe- dance...can give information of the electrical characte- ristics of tissue. In some cases the conductivity gra- dient can be an important value. The

  2. Electrical measurements in the atmosphere and the Ionosphere over an active thunderstorm. II - Direct current electric fields and conductivity

    NASA Technical Reports Server (NTRS)

    Holzworth, R. H.; Kelley, M. C.; Siefring, C. L.; Hale, L. C.; Mitchell, J. D.

    1985-01-01

    On August 9, 1981, a series of three rockets was launched over an air mass thunderstorm off the eastern seaboard of Virginia while simultaneous stratospheric and ground-based electric field measurements were made. The conductivity was substantially lower at most altitudes than the conductivity profiles used by theoretical models. Direct current electric fields over 80 mV/m were measured as far away as 96 km from the storm in the stratosphere at 23 km altitude. No dc electric fields above 75 km altitude could be identified with the thunderstorm, in agreement with theory. However, vertical current densities over 120 pA/sq m were seen well above the classical 'electrosphere' (at 50 or 60 km). Frequent dc shifts in the electric field following lightning transients were seen by both balloon and rocket payloads. These dc shifts are clearly identifiable with either cloud-to-ground (increases) or intercloud (decreases) lightning flashes.

  3. Hydrothermal fault zone mapping using seismic and electrical measurements

    NASA Astrophysics Data System (ADS)

    Onacha, Stephen Alumasa

    This dissertation presents a new method of using earthquakes and resistivity data to characterize permeable hydrothermal reservoirs. The method is applied to field examples from Casa Diablo in the Long Valley Caldera, California; Mt. Longonot, Kenya; and Krafla, Iceland. The new method has significant practical value in the exploration and production of geothermal energy. The method uses P- and S-wave velocity, S-wave polarization and splitting magnitude, resistivity and magnetotelluric (MT) strike directions to determine fracture-porosity and orientation. The conceptual model used to characterize the buried, fluid-circulating fault zones in hydrothermal systems is based on geological and fracture models. The method has been tested with field earthquake and resistivity data; core samples; temperature measurements; and, for the case of Krafla, with a drilled well. The use of resistivity and microearthquake measurements is based on theoretical formulation of shared porosity, anisotropy and polarization. The relation of resistivity and a double porosity-operator is solved using a basis function. The porosity-operator is used to generate a correlation function between P-wave velocity and resistivity. This correlation is then used to generate P-wave velocity from 2-D resistivity models. The resistivity models are generated from magnetotelluric (MT) by using the Non-Linear Conjugate Gradient (NLCG) inversion method. The seismic and electrical measurements used come from portable, multi station microearthquake (MEQ) monitoring networks and multi-profile, MT and transient electromagnetic (TEM) observation campaigns. The main conclusions in this dissertation are listed below: (1) Strong evidence exists for correlation between MT strike direction and anisotropy and MEQ S-wave splitting at sites close to fluid-filled fracture zones. (2) A porosity operator generated from a double porosity model has been used to generate valid P-wave velocity models from resistivity data. This

  4. Simultaneous electric-field measurements on nearby balloons.

    NASA Technical Reports Server (NTRS)

    Mozer, F. S.

    1972-01-01

    Electric-field payloads were flown simultaneously on two balloons from Great Whale River, Canada, on September 21, 1971, to provide data at two points in the upper atmosphere that differed in altitude by more than one atmospheric density scale height and in horizontal position by 30-140 km. The altitude dependences in the two sets of data prove conclusively that the vertical electric field at balloon altitudes stems from fair-weather atmospheric electricity sources and that the horizontal fields are mapped down ionospheric fields, since the weather-associated horizontal fields were smaller than 2 mV/m.

  5. Electric field simulation and measurement of a pulse line ion accelerator

    NASA Astrophysics Data System (ADS)

    Shen, Xiao-Kang; Zhang, Zi-Min; Cao, Shu-Chun; Zhao, Hong-Wei; Wang, Bo; Shen, Xiao-Li; Zhao, Quan-Tang; Liu, Ming; Jing, Yi

    2012-07-01

    An oil dielectric helical pulse line to demonstrate the principles of a Pulse Line Ion Accelerator (PLIA) has been designed and fabricated. The simulation of the axial electric field of an accelerator with CST code has been completed and the simulation results show complete agreement with the theoretical calculations. To fully understand the real value of the electric field excited from the helical line in PLIA, an optical electric integrated electric field measurement system was adopted. The measurement result shows that the real magnitude of axial electric field is smaller than that calculated, probably due to the actual pitch of the resister column which is much less than that of helix.

  6. Polarization resolved electric field measurements on plasma bullets in N2 using four-wave mixing

    NASA Astrophysics Data System (ADS)

    van der Schans, Marc; Boehm, Patrick; Nijdam, Sander; Ijzerman, Wilbert; Czarnetzki, Uwe

    2016-09-01

    Atmospheric pressure plasma jets generated by kHz AC or pulsed DC voltages typically consist of discrete guided ionization waves called plasma bullets. In this work, the electric field of plasma bullets generated in a pulsed DC jet with N2 as feed gas is investigated using the four-wave mixing method. In this diagnostic two laser beams, where one is Stokes shifted from the other, non-linearly interact with the N2 molecules and the bullet's electric field. As a result of the interaction a coherent anti-Stokes Raman scattered (CARS) beam and an infrared beam are generated from which the electric field can be determined. Compared to emission-based methods, this technique has the advantage of being able to also probe the electric field in regions around the plasma bullet where no photons are emitted. The four-wave mixing method and its analysis have been adapted to work with the non-uniform electric field of plasma bullets. In addition, an ex-situ calibration procedure using an electrode geometry different from the discharge geometry has been developed. An experimentally obtained radial profile of the axial electric field component of a plasma bullet in N2 is presented. The position of this profile is related to the location of the propagating bullet from temporally resolved images.

  7. High temperature setup for measurements of Seebeck coefficient and electrical resistivity of thin films using inductive heating

    NASA Astrophysics Data System (ADS)

    Adnane, L.; Williams, N.; Silva, H.; Gokirmak, A.

    2015-10-01

    We have developed an automated setup for simultaneous measurement of Seebeck coefficient S(T) and electrical resistivity ρ(T) of thin film samples from room temperature to ˜650 °C. S and ρ are extracted from current-voltage (I-V) measurements obtained using a semiconductor parameter analyzer and temperature measurements obtained using commercial thermocouples. The slope and the x-axis intercept of the I-V characteristics represent the sample conductance G and the Seebeck voltage, respectively. The measured G(T) can be scaled to ρ(T) by the geometry factor obtained from the room temperature resistivity measurement of the film. The setup uses resistive or inductive heating to control the temperature and temperature gradient on the sample. Inductive heating is achieved with steel plates that surround the test area and a water cooled copper pipe coil underneath that generates an AC magnetic field. The measurements can be performed using resistive heating only or inductive heating only, or a combination of both depending on the desired heating ranges. Inductive heating provides a more uniform heating of the test area, does not require contacts to the sample holder, can be used up to the Curie temperature of the particular magnetic material, and the temperature gradients can be adjusted by the relative positions of the coil and sample. Example results obtained for low doped single-crystal silicon with inductive heating only and with resistive heating only are presented.

  8. Electrical and thermal transport measurements on nano-structured materials

    NASA Astrophysics Data System (ADS)

    Chang, Chih-Wei

    This thesis discusses electrical and thermal transport measurements on C60, carbon nanotubes, and boron-nitride nanotubes. Chapter 1 describes the anomalous resistivity behavior of Ag films on C60 crystals. The correlation of the resistivity anomaly and the structural phase transition is established. Chapter 2 gives an introduction to the physical properties and the synthesis methods of carbon and boron nitride nanotubes. Chapter 3 shows two different approaches on chemical functionalization of boron-nitride nanotubes. Chapter 4 gives the theoretical background of thermal conductivity, especially for nano-structured materials. A summary of theoretical and experimental works on the thermal conductivity of nanotubes is given. Chapter 5 discusses the experimental results of thermal conductivity of nanotube mats. An absolute value of the thermal conductivity of boron nitride nanotubes is bracketed and can be compared to the results of the following chapters on individual nanotubes. Chapter 6 describes the experimental methods of measuring thermal conductivity of individual nanotubes. Chapter 7 shows the 2 temperature dependent thermal conductivity and thermopower of individual nanotubes. Chapter 8 discusses the isotope effect and the diameter dependence of the thermal conductivity of nanotubes. In chapter 9, it is shown that the thermal conductivity of nanotubes is robust against electron irradiation and structural deformation. Importantly, the observation challenges current understandings on the thermal transport of nano-structured materials. In chapter 10, it is shown that it is possible to reversibly tune the thermal conductivity of a multiwalled nanotube by controllably sliding the outer-shells against inner cores. Chapter 11 describes a thermal rectifier by engineering the mass distribution along a nanotube. The observed non-zero thermal rectification effect provides strong evidence for solitons in nanotubes. The soliton model also coherently explains many

  9. Determining the operating performance through electrical measurements of a hydro generator

    NASA Astrophysics Data System (ADS)

    Haţiegan, C.; Chioncel, C. P.; Răduca, E.; Popescu, C.; Pădureanu, I.; Jurcu, M. R.; Bordeaşu, D.; Trocaru, S.; Dilertea, F.; Bădescu, O.; Terfăloagă, I. M.; Băra, A.; (Barboni Haţiegan, L.

    2017-01-01

    This paper presents the results obtained by experimental measurements regarding the determining of the operating performance of a Hydro generator, through electrical measurements before the refurbishment of hydro aggregates. Experimental measurements were taken to determine the characteristic by putting off load and also by putting on load regimes for power between 1 and 5 MW of hydro generator. These electrical measurements are to establish appropriate measures in terms of constructive and functional in order to bring the nominal parameters of that hydro aggregate.

  10. An Ultra-Precise System for Electrical Resistivity Tomography Measurements

    SciTech Connect

    LaBrecque, Douglas J; Adkins, Paula L

    2008-12-09

    The objective of this research was to determine the feasibility of building and operating an ERT system that will allow measurement precision that is an order of magnitude better than existing systems on the market today and in particular if this can be done without significantly greater manufacturing or operating costs than existing commercial systems. Under this proposal, we performed an estimation of measurement errors in galvanic resistivity data that arise as a consequence of the type of electrode material used to make the measurements. In our laboratory, measurement errors for both magnitude and induced polarization (IP) were estimated using the reciprocity of data from an array of electrodes as might be used for electrical resistance tomography using 14 different metals as well as one non-metal - carbon. In a second phase of this study, using archival data from two long-term ERT surveys, we examined long-term survivability of electrodes over periods of several years. The survey sites were: the Drift Scale Test at Yucca Mountain, Nevada (which was sponsored by the U. S. Department of Energy as part of the civilian radioactive waste management program), and a water infiltration test at a site adjacent to the New Mexico Institute of Mines and Technology in Socorro, New Mexico (sponsored by the Sandia/Tech vadose program). This enabled us to compare recent values with historical values and determine electrode performance over the long-term as well as the percentage of electrodes that have failed entirely. We have constructed a prototype receiver system, made modifications and revised the receiver design. The revised prototype uses a new 24 bit analog to digital converter from Linear Technologies with amplifier chips from Texas Instruments. The input impedance of the system will be increased from 107 Ohms to approximately 1010 Ohms. The input noise level of the system has been decreased to approximately 10 Nanovolts and system resolution to about 1 Nanovolt at

  11. Examination of Humidity Effects on Measured Thickness and Interfacial Phenomena of Exfoliated Graphene on SiO2 via AC-AFM

    NASA Astrophysics Data System (ADS)

    Jinkins, Katherine; Camacho, Jorge; Farina, Lee; Wu, Yan

    2015-03-01

    Tapping (AC) mode Atomic Force Microscopy (AFM) is commonly used to determine the thickness of graphene samples. However, AFM measurements have been shown to be sensitive to environmental conditions such as adsorbed water, in turn dependent on relative humidity (RH). In the present study, AC-AFM is used to measure the thickness and loss tangent of exfoliated graphene on silicon dioxide (SiO2) as RH is increased from 10% to 80%. We show that the measured thickness of graphene is dependent on RH. Loss tangent is an AFM imaging technique that interprets the phase information as a relationship between the stored and dissipated energy in the tip-sample interaction. This study demonstrates the loss tangent of the graphene and oxide regions are both affected by humidity, with generally higher loss tangent for graphene than SiO2. As RH increases, we observe the loss tangent of both materials approaches the same value. We hypothesize that there is a layer of water trapped between the graphene and SiO2 substrate to explain this observation. Using this interpretation, the loss tangent images also indicate movement and change in this trapped water layer as RH increases, which impacts the measured thickness of graphene using AC-AFM.

  12. Fiber-optic sensors for aerospace electrical measurements - An update

    NASA Technical Reports Server (NTRS)

    Patterson, Richard L.; Rose, A. H.; Tang, D.; Day, G. W.

    1991-01-01

    The authors report the progress made on the development of aerospace current and voltage sensors which use fiber-optic and optical sensing heads. These sensors are presently designed to cover ac frequencies from 60 Hz to 20 kHz. The current sensor, based on the Faraday effect in optical fiber, is in advanced development after some initial testing. The emphasis is on packaging methods and ways to maintain consistent sensitivity with changes in temperature. The voltage sensor, utilizing the Pockels effect in a crystal, has excelled in temperature tests. The authors report on the development of these sensors. The authors also relate the technology used in the sensors, the results of evaluation, improvements being made, and the future direction of the work.

  13. Study of Electrical Conduction Mechanism of Organic Double-Layer Diode Using Electric Field Induced Optical Second Harmonic Generation Measurement.

    PubMed

    Nishi, Shohei; Taguchi, Dai; Manaka, Takaaki; Iwamoto, Mitsumasa

    2016-04-01

    By using electric field induced optical second harmonic generation (EFISHG) and current voltage (I-V) measurements, we studied the electrical transport mechanism of organic double-layer diodes with a structure of Au/N, N'-di-[(1-naphthyl)-N, N'-diphenyl]-(1,1'-biphenyl)-4,4'-diamine (a-NPD)/poly(methyl methacrylate) (PMMA)/indium zinc oxide (IZO). Here the α-NPD is a carrier transport layer and the PMMA is an electrical insulating layer. The current level was very low, but the I-V characteristics showed a rectifying behavior. The EFISHG measurement selectively and directly probed the electric field across the α-NPD layer, and showed that the electric field across the a-NPD layer is completely relaxed owing to the charge accumulation at the a-NPD/PMMA interface in the region V > 0, whereas the carrier accumulation was not significant in the region V < 0. On the basis of these experimental results, we proposed a model of the rectification. Further, by coupling the I-V characteristics with the EFISHG measurement, the I-V characteristics of the diodes were well converted into the current-electric field (I-E) characteristics of the α-NPD layer and the PMMA layer. The I-E characteristics suggested the Schottky-type conduction governs the carrier transport. We conclude that the I-V measurement coupled with the EFISHG measurement is very useful to study carrier transport mechanism of the organic double-layer diodes.

  14. Electric field measuring and display system. [for cloud formations

    NASA Technical Reports Server (NTRS)

    Wojtasinski, R. J.; Lovall, D. D. (Inventor)

    1974-01-01

    An apparatus is described for monitoring the electric fields of cloud formations within a particular area. It utilizes capacitor plates that are alternately shielded from the clouds for generating an alternating signal corresponding to the intensity of the electric field of the clouds. A synchronizing signal is produced for controlling sampling of the alternating signal. Such samplings are fed through a filter and converted by an analogue to digital converter into digital form and subsequently fed to a transmitter for transmission to the control station for recording.

  15. Progress towards an electron electric dipole moment measurement with laser-cooled atoms

    NASA Astrophysics Data System (ADS)

    Solmeyer, Neal

    This dissertation recounts the progress made towards a measurement of the electron electric dipole moment. The existence of a permanent electric dipole moment of any fundamental particle would imply that both time reversal and parity invariance are violated. If an electric dipole moment were measured within current experimental limits it would be the first direct evidence for physics beyond the standard model. For our measurement we use laser-cooled alkali atoms trapped in a pair of 1D optical lattices. The lattices run through three electric field plates so that the two groups of atoms see opposing electric fields. The measurement chamber is surrounded by a four layer mu-metal magnetic shield. Under electric field quantization, the atoms are prepared in a superposition of magnetic sublevels that is sensitive to the electron electric dipole moment in Ramsey-like spectroscopy. The experiment requires very large electric fields and very small magnetic fields. Engineering a system compatible with both of these goals simultaneously is not trivial. Searches for electric dipole moments using neutral atoms in optical lattices have much longer possible interaction times and potentially give more precise information about the inherent symmetry breaking than other methods. This comes at the cost of a higher sensitivity to magnetic fields and possible sources of error associated with the trapping light. If noise and systematic errors can be controlled to our design specifications our experiment will significantly improve the current experimental limit of the electron electric dipole moment.

  16. Body Fat Measurement: Weighing the Pros and Cons of Electrical Impedance.

    ERIC Educational Resources Information Center

    Nash, Heyward L.

    1985-01-01

    Research technologists have developed electrical impedance units in response to demand for a convenient and reliable method of measuring body fat. Accuracy of impedance measures versus calipers and underwater weighing are discussed. (MT)

  17. Regular structures in 5CB liquid crystals under the joint action of ac and dc voltages

    NASA Astrophysics Data System (ADS)

    Aguirre, Luis E.; Anoardo, Esteban; Éber, Nándor; Buka, Ágnes

    2012-04-01

    A nematic liquid crystal with high, positive dielectric anisotropy (5CB) has been studied under the influence of the combined action of a dc and an ac electric field. Broad frequency, voltage, and cell thickness ranges were considered. Pattern morphologies were identified; the thresholds and critical wave numbers were measured and analyzed as a function of frequency, dc-to-ac voltage ratio, and thickness. The current-voltage characteristics were simultaneously detected.

  18. Electricity

    SciTech Connect

    Sims, B.

    1983-01-01

    Historical aspects of electricity are reviewed with individual articles on hydroelectric dams, coal-burning power plants, nuclear power plants, electricity distribution, and the energy future. A glossary is included. (PSB)

  19. Simultaneous distribution of AC and DC power

    DOEpatents

    Polese, Luigi Gentile

    2015-09-15

    A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.

  20. Improvement of electrical blood hematocrit measurements under various plasma conditions using a novel hematocrit estimation parameter.

    PubMed

    Kim, Myounggon; Kim, Ayoung; Kim, Sohee; Yang, Sung

    2012-05-15

    This paper presents an electrical method for measurement of Hematocrit (HCT) using a novel HCT estimation parameter. Particularly in the case of electrical HCT measurements, the measurement error generally increases with changes in the electrical conditions of the plasma such as conductivity and osmolality. This is because the electrical properties of blood are a function not only of HCT, but also of the electrical conditions in the plasma. In an attempt to reduce the measurement errors, we herein propose a novel HCT estimation parameter reflecting the characteristics of both the changes in volume of red blood cells (RBCs) and electrical conditions of plasma, simultaneously. In order to characterize the proposed methods under various electrical conditions of plasma, we prepared twelve blood samples such as four kinds of plasma conditions (hypotonic, isotonic, two kinds of hypertonic conditions) at three different HCT levels. Using linear regression analysis, we confirmed that the proposed parameter was highly correlated with reference HCT (HCT(ref.)) values measured by microcentrifugation. Thus, the HCT measurement error was less than 4%, despite considerable variations in the conductivity and osmolality of the plasma at conditions of the HCT(ref.) of 20%. Multiple linear regression analysis showed that the proposed HCT estimation parameter also yielded a lower measurement error (1%) than the other parameter previously used for the same purpose. Thus, these preliminary results suggest that proposed method could be used for accurate, fast, easy, and reproducible HCT measurements in medical procedures.

  1. AC/DC converter

    NASA Astrophysics Data System (ADS)

    Jain, Praveen K.

    1992-08-01

    In a system such as a 20 kHz space station primary electrical power distribution system, power conversion from AC to DC is required. Some of the basic requirements for this conversion are high efficiency, light weight and small volume, regulated output voltage, close to unity input power factor, distortionless input current, soft-starting, low electromagnetic interference, and high reliability. An AC-to-DC converter is disclosed which satisfies the main design objectives of such converters for use in space. The converter of the invention comprises an input transformer, a resonant network, a current controller, a diode rectifier, and an output filter. The input transformer is for connection to a single phase, high frequency, sinusoidal waveform AC voltage source and provides a matching voltage isolating from the AC source. The resonant network converts this voltage to a sinusoidal, high frequency bidirectional current output, which is received by the current controller to provide the desired output current. The diode rectifier is connected in parallel with the current controller to convert the bidirectional current into a unidirectional current output. The output filter is connected to the rectifier to provide an essentially ripple-free, substantially constant voltage DC output.

  2. Microspacecraft and Earth observation: Electrical field (ELF) measurement project

    NASA Technical Reports Server (NTRS)

    Olsen, Tanya; Elkington, Scot; Parker, Scott; Smith, Grover; Shumway, Andrew; Christensen, Craig; Parsa, Mehrdad; Larsen, Layne; Martinez, Ranae; Powell, George

    1990-01-01

    The Utah State University space system design project for 1989 to 1990 focuses on the design of a global electrical field sensing system to be deployed in a constellation of microspacecraft. The design includes the selection of the sensor and the design of the spacecraft, the sensor support subsystems, the launch vehicle interface structure, on board data storage and communications subsystems, and associated ground receiving stations. Optimization of satellite orbits and spacecraft attitude are critical to the overall mapping of the electrical field and, thus, are also included in the project. The spacecraft design incorporates a deployable sensor array (5 m booms) into a spinning oblate platform. Data is taken every 0.1 seconds by the electrical field sensors and stored on-board. An omni-directional antenna communicates with a ground station twice per day to down link the stored data. Wrap-around solar cells cover the exterior of the spacecraft to generate power. Nine Pegasus launches may be used to deploy fifty such satellites to orbits with inclinations greater than 45 deg. Piggyback deployment from other launch vehicles such as the DELTA 2 is also examined.

  3. Mutual-induction measurement of the AC penetration depth in HTSC's theory of calibration function for flat samples under axial symmetry

    NASA Astrophysics Data System (ADS)

    Klupsch, Th.; Zeisberger, M.

    1995-02-01

    A contribution to find optimum mutual-induction arrangements for investigating the linear AC response properties of the pinned vortices in the mixed state of HTSC is given. In particular, the complex calibration function (mutual-induction coefficient L12 as a function of the complex AC penetration depth λ) is analyzed, strictly axial symmetry and flat sample geometries provided (finite disk and its limiting case of infinite platelet) assuming the radius of at least one induction coil is smaller than the sample radius. Because the sample is positioned transverse to the AC induction B, the mutual inductance becomes, in general, strongly modified by distortions of B around the sample, which results in a strong dependence of L12(λ) upon certain geometry parameters and an enhanced sensitivity to λ for selected |λ| intervals. The analysis is based upon powerful analytic approximation formulae for elementary arrangements derived in a separate paper. Also, formulae to estimate the errors from irregular (eccentric) sample shapes, from the field enhancement near the disk edges as well as from treating the finite-disk problem in the limit of an infinite platelet are given. Except for ultrathin films with thickness much smaller than |λ|, arrangements with both the coils at the same sample side and with the loop radii sufficiently smaller than the disk radius are favored for measurements of small λ with |D/λ| ≳ 1 ( D is the sample thickness), which also includes the possibility of a λ measurement in the bulk limit | D/λ| → ∞.

  4. Total AC loss study of 2G HTS coils for fully HTS machine applications

    NASA Astrophysics Data System (ADS)

    Zhang, Min; Yuan, Weijia; Kvitkovic, Jozef; Pamidi, Sastry

    2015-11-01

    The application of HTS coils for fully HTS machines has become a new research focus. In the stator of an electrical machine, HTS coils are subjected to a combination of an AC applied current and AC external magnetic field. There is a phase shift between the AC current and AC magnetic field. In order to understand and estimate the total AC loss of HTS coils for electrical machines, we designed and performed a calorimetric measurement for a 2G HTS racetrack coil. Our measurement indicates that the total AC loss is greatly influenced by the phase shift between the applied current and the external magnetic field when the magnetic field is perpendicular to the tape surface. When the applied current and the external magnetic field are in phase, the total AC loss is the highest. When there is a 90 degree phase difference, the total AC loss is the lowest. In order to explain this phenomenon, we employ H formulation and finite element method to model the 2G HTS racetrack coil. Our calculation agrees well with experimental measurements. Two parameters are defined to describe the modulation of the total AC loss in terms of phase difference. The calculation further reveals that the influence of phase difference varies with magnetic field direction. The greatest influence of phase difference is in the perpendicular direction. The study provides key information for large-scale 2G HTS applications, e.g. fully HTS machines and superconducting magnetic energy storage, where the total AC loss subjected to both applied currents and external magnetic fields is a critical parameter for the design.

  5. HVDC-AC system interaction from AC harmonics. Volume 1. Harmonic impedance calculations. Final report

    SciTech Connect

    Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R

    1982-09-01

    Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.

  6. Using impedance measurements for detecting pathogens trapped in an electric field

    DOEpatents

    Miles, Robin R.

    2004-07-20

    Impedance measurements between the electrodes in an electric field is utilized to detect the presence of pathogens trapped in the electric field. Since particles trapped in a field using the dielectiphoretic force changes the impedance between the electrodes by changing the dielectric material between the electrodes, the degree of particle trapping can be determined by measuring the impedance. This measurement is used to determine if sufficient pathogen have been collected to analyze further or potentially to identify the pathogen.

  7. Apparatus for electrical measurements of thin films from 77 to 1000 K

    NASA Technical Reports Server (NTRS)

    Matus, L. G.; Summers, R. L.

    1986-01-01

    A novel method of mounting thin samples for electrical measurements is described. A vacuum chuck holds a mounting plate, which, in turn, holds the sample. Contacts on the mounting plate establish electrical connection to the sample. The attachment of wires directly to the samples is unnecessary. Measurements can be made at temperatures from 77 to 1000 K. As an application of the apparatus, resistivity and Hall measurements of a thin silicon carbide sample are presented.

  8. Performance measurements and operational characteristics of the Storage Tek ACS 4400 tape library with the Cray Y-MP EL

    NASA Technical Reports Server (NTRS)

    Hull, Gary; Ranade, Sanjay

    1993-01-01

    With over 5000 units sold, the Storage Tek Automated Cartridge System (ACS) 4400 tape library is currently the most popular large automated tape library. Based on 3480/90 tape technology, the library is used as the migration device ('nearline' storage) in high-performance mass storage systems. In its maximum configuration, one ACS 4400 tape library houses sixteen 3480/3490 tape drives and is capable of holding approximately 6000 cartridge tapes. The maximum storage capacity of one library using 3480 tapes is 1.2 TB and the advertised aggregate I/O rate is about 24 MB/s. This paper reports on an extensive set of tests designed to accurately assess the performance capabilities and operational characteristics of one STK ACS 4400 tape library holding approximately 5200 cartridge tapes and configured with eight 3480 tape drives. A Cray Y-MP EL2-256 was configured as its host machine. More than 40,000 tape jobs were run in a variety of conditions to gather data in the areas of channel speed characteristics, robotics motion, time taped mounts, and timed tape reads and writes.

  9. A MSE Polarimetry diagnostic for the measurement of radial electric fields on the HSX stellarator

    NASA Astrophysics Data System (ADS)

    Dobbins, T. J.; Kumar, S. T. A.; Anderson, F. S. B.; Anderson, D. T.

    2016-10-01

    The radial electric field in HSX has been measured using the Charge Exchange Recombination Spectroscopy. These impurity ion flow measurements could not resolve a large positive radial electric field (40-50 kV/m) near the core of the HSX plasma, predicted by neoclassical codes. A dual PEM (Photo Elastic Modulator) MSE polarimetry system has been designed for direct measurement of the radial electric field in the HSX plasma. The polarimetry design has been optimized to get a maximum change in polarization angle from an electric field while still providing good spatial resolution. It is expected that a radial electric field as small as 7 kV/m can be detected. The initial results of the system on an available port will be presented. The choice and design of the optics for the optimal viewing port will also be presented. This work is supported by US DOE Grant DE-FG02-93ER54222.

  10. Reconstructing solid state nanopore shape from electrical measurements

    NASA Astrophysics Data System (ADS)

    Liebes, Yael; Drozdov, Maria; Avital, Yotam Y.; Kauffmann, Yaron; Rapaport, Hanna; Kaplan, Wayne D.; Ashkenasy, Nurit

    2010-11-01

    The dependence of nanopore biosensor conductance signal on the nanopore shape makes it important to decipher the latter with high precision. We show here that the three dimensional shape of a nanopore, extracted from electron microscopy analysis, allows for modeling the conductance of the nanopore over a wide range of ionic strengths. Furthermore, we demonstrate that the dependence of the nanopore conductance on ionic strength can be used to accurately extract the nanopore shape, eliminating the need for lengthy electron microscopy analysis. The suggested methodology can be used to monitor changes in the nanopore shape and evaluate them during electrical characterization.

  11. Measurement of submilliwatt, picosecond terahertz emission from a femtosecond-laser-pumped solid-state dc to ac radiation converter based on a ZnSe crystal

    SciTech Connect

    Yugami, Noboru; Ohata, Nobuo; Yaegashi, Kenta; Kawanago, Hiroshi

    2006-11-15

    We measured the terahertz pulse emission from a femtosecond-laser-pumped solid-state dc to ac radiation converter using a 150 fs Ti:sapphire laser pulse for dense plasma diagnostics. The laser-produced ionization front was directly modulated from a periodic electrostatic field to pulsed emission. The central frequency of the emission was measured to be 0.13 THz having a bandwidth of 0.1 THz and a peak power of 0.2 mW. This emission source is suitable for use in various novel diagnostic techniques, such as dense plasma diagnostics.

  12. Procedure for measuring electrical resistivity of anisotropic materials: A revision of the Montgomery method

    NASA Astrophysics Data System (ADS)

    dos Santos, C. A. M.; de Campos, A.; da Luz, M. S.; White, B. D.; Neumeier, J. J.; de Lima, B. S.; Shigue, C. Y.

    2011-10-01

    A procedure for determining the electrical resistivity of anisotropic materials is presented. It offers several improvements to the well-known Montgomery method. One improvement, in particular, is the ability to obtain the electrical resistivity for all three axes of an orthorhombic crystal analytically, rather than using the iterative approach suggested by Montgomery for the third axis. All necessary equations are derived and their application in determining the tensor components of the electrical resistivity is explained in detail. Measurements on isotropic specimens were executed in order to test the foundations of the method. Measurements on anisotropic samples are compared with measurements obtained by using the standard four-probe method, revealing good agreement.

  13. Fusion Research of Electrical Tomography with Other Sensors for Two-phase Flow Measurement

    NASA Astrophysics Data System (ADS)

    Deng, Xiang; Yang, W. Q.

    2012-01-01

    The two-phase flow widely exists in the nature and industrial processes. The measurement of two-phase flows, including gas/solids, gas/liquid and liquid/liquid flows, is still challenging. Fusions of electrical tomography with conventional sensors provide possibilities to improve two-phase flow accurate measurement. In this paper, fusions of (1) electrical resistance tomography (ERT) with electromagnetic (EM) flowmeter, (2) electrical capacitance tomography (ECT) with ERT and (3) ECT with electrostatic sensor are introduced. Some research results of fusion methods are presented and discussed. This paper can provide the theoretical support for the multi-sensor fusion for two-phase flow measurement.

  14. Automated electric charge measurements of fluid microdrops using the Millikan method

    NASA Astrophysics Data System (ADS)

    Lee, Eric R.; Halyo, Valerie; Lee, Irwin T.; Perl, Martin L.

    2004-10-01

    Automated measurements of the electric charge of fluid microdrops precise to up to 0.016 of an electron charge have been made using machine-vision systems to observe the motion of fluid microdrops in air under the influence of an oscillating electric field. The fluid drop diameters have ranged from 7 µm to 25 µm with smaller diameter drops being measured to higher precision. The experimental runs performed for the purpose of attempting to find isolated fractionally electrically charged particles have measured the charges of tens of millions of fluid microdrops using piezoelectrically driven drop-on-demand inkjet-like droplet ejectors as fluid drop sources.

  15. In-situ measurement of the electrical conductivity of aluminum oxide in HFIR

    SciTech Connect

    Zinkle, S.J.; White, D.P.; Snead, L.L.

    1996-10-01

    A collaborative DOE/Monbusho irradiation experiment has been completed which measured the in-situ electrical resistivity of 12 different grades of aluminum oxide during HFIR neutron irradiation at 450{degrees}C. No evidence for bulk RIED was observed following irradiation to a maximum dose of 3 dpa with an applied dc electric field of 200 V/mm.

  16. The Electrical Measurement by Sounding Balloons and a Flexibility Study on the Artificially Triggered TLEs

    NASA Astrophysics Data System (ADS)

    Wen, S.; Chuang, C.; Chiu, C.; Chen, A. B.

    2013-12-01

    The atmospheric electric field plays an important role in driving the global electric circuit, as well as the theoretical models of the transient luminous events (TLEs). The measurement of the electric field in the upper atmosphere, especially above cloud top to the bottom of the ionosphere is very challenging but essential. A lightweight, double-Langmuir type probe of the electric field meter is greatly improved for the balloon-borne measurement. Instead of scientific balloons, the meteorological balloons are used to send this electric field meter to up to 30km height and measure the vertical profile of the atmospheric electric field, and the vertical charge density can also be derived simultaneously. In this presentation, the result of a flight is demonstrated. In addition to the measurement of the electric filed, the artificial TLEs triggered from meteorological balloon is also considered. A simple electrodynamic model similar to Krehbiel et al. [2008] is adapted to explore the possibility and conditions to induce the electric field breakdown and produce artificial TLEs by cooper wires in the upper atmosphere. The preliminary results are also reported.

  17. Aircraft electric field measurements: Calibration and ambient field retrieval

    NASA Technical Reports Server (NTRS)

    Koshak, William J.; Bailey, Jeff; Christian, Hugh J.; Mach, Douglas M.

    1994-01-01

    An aircraft locally distorts the ambient thundercloud electric field. In order to determine the field in the absence of the aircraft, an aircraft calibration is required. In this work a matrix inversion method is introduced for calibrating an aircraft equipped with four or more electric field sensors and a high-voltage corona point that is capable of charging the aircraft. An analytic, closed form solution for the estimate of a (3 x 3) aircraft calibration matrix is derived, and an absolute calibration experiment is used to improve the relative magnitudes of the elements of this matrix. To demonstrate the calibration procedure, we analyze actual calibration date derived from a Lear jet 28/29 that was equipped with five shutter-type field mill sensors (each with sensitivities of better than 1 V/m) located on the top, bottom, port, starboard, and aft positions. As a test of the calibration method, we analyze computer-simulated calibration data (derived from known aircraft and ambient fields) and explicitly determine the errors involved in deriving the variety of calibration matrices. We extend our formalism to arrive at an analytic solution for the ambient field, and again carry all errors explicitly.

  18. Tevatron AC dipole system

    SciTech Connect

    Miyamoto, R.; Kopp, S.E.; Jansson, A.; Syphers, M.J.; /Fermilab

    2007-06-01

    The AC dipole is an oscillating dipole magnet which can induce large amplitude oscillations without the emittance growth and decoherence. These properties make it a good tool to measure optics of a hadron synchrotron. The vertical AC dipole for the Tevatron is powered by an inexpensive high power audio amplifier since its operating frequency is approximately 20 kHz. The magnet is incorporated into a parallel resonant system to maximize the current. The use of a vertical pinger magnet which has been installed in the Tevatron made the cost relatively inexpensive. Recently, the initial system was upgraded with a more powerful amplifier and oscillation amplitudes up to 2-3{sigma} were achieved with the 980 GeV proton beam. This paper discusses details of the Tevatron AC dipole system and also shows its test results.

  19. Laser-spectroscopic electric field measurements in a ns-pulsed microplasma in nitrogen

    NASA Astrophysics Data System (ADS)

    Boehm, Patrick; Luggenhoelscher, Dirk; Czarnetzki, Uwe; 1123 Research Group Collaboration

    2013-09-01

    In this work for the first time ns-pulsed discharges in nitrogen at near atmospheric pressures are investigated by laser-spectroscopic electric field measurements, ultra-fast optical emission spectroscopy, current and voltage measurements. The discharge is operated with kV-pulses of about 150 ns duration between two parallel plate electrodes with a 1.2 mm gap. The laser technique for electric field measurement is based on a four-wave mixing process similar to Coherent anti-Stokes Raman Scattering (CARS). Here the static electric field acts effectively as the third wave with a zero frequency. The frequency of the generated anti-Stokes wave is in the IR regime and the amplitude is proportional to the electric field strength. By measuring the intensity of the IR- and anti-Stokes-signal it is now possible to determine the static electric field. Due to the short pulse-length of the lasers a temporal resolution in the ns range and a typical sensitivity of 50 - 100 V/mm in pure nitrogen is achieved (p > 50 mbar). Field-measurements are accompanied by emission measurements using a streak-camera with sub-ns resolutions. Further, current and voltage measurements combined with the electric field measurements allow determination of the plasma density. Funding by DFG through FOR 1123.

  20. CRIT II electric, magnetic, and density measurements within an ionizing neutral stream

    NASA Technical Reports Server (NTRS)

    Swenson, C. M.; Kelley, M. C.; Primdahl, F.; Baker, K. D.

    1990-01-01

    Measurements from rocket-borne sensors inside a high-velocity neutral barium beam show a-factor-of-six increase in plasma density in a moving ionizing front. This region was colocated with intense fluctuating electric fields at frequencies well under the lower hybrid frequency for a barium plasma. Large quasi-dc electric and magnetic field fluctuations were also detected with a large component of the current and the electric field parallel to B(0). An Alfven wave with a finite electric field component parallel to the geomagnetic field was observed to propagate along B(0), where it was detected by an instrumented subpayload.

  1. Electrical current measurement system for energy harvesting applications

    NASA Astrophysics Data System (ADS)

    Heller, S.; Mueller, F.; Kroener, M.; Woias, P.

    2016-11-01

    The measurement of the dynamic power consumption is an important task in the field of energy harvesting regarding the characterization and optimization of low power systems. This paper reports on the development and characterization of a computer-controlled measurement system for the measurement of the dynamic current consumption of low power systems in a range from 100 nA to 100 μA, with a time resolution down to 1 μs.

  2. Electrical Measurement of Single Molecule Catalysis using Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Goldsmith, Brett R.; Kane, Alexander A.; Khalap, Vaikunth; Coroneus, John; Weiss, Gregory A.; Collins, Philip G.

    2008-03-01

    We demonstrate single molecule chemical sensors based on single-walled carbon nanotubes (SWNT). The architecture uses a SWNT conductor having a single, reactive species covalently bonded to the sidewall [1]. Dynamics of the molecule are electrically transduced as it interacts with its surrounding environment. As a test case, we investigate the catalytic modification of EDC by a carboxylate. After creating a carboxylate terminus on the SWNT, the circuit is monitored for several hours and through hundreds of individual EDC reactions. Statistical analysis determines the lifetime of the carboxyl-EDC complex, as well as the catalytic turnover rate, from discrete events. Because the carboxylate site can be readily derivatized with proteins, peptides, or other functional molecules, the technique shows promise as a tool for single molecule research independent of optics and scanning probe microscopy. 1. B.R. Goldsmith, et al. Science 315, 77 (2007).

  3. Multifunctional probes for high-throughput measurement of Seebeck coefficient and electrical conductivity at room temperature

    NASA Astrophysics Data System (ADS)

    García-Cañadas, Jorge; Min, Gao

    2014-04-01

    An apparatus capable of rapid measurement of the Seebeck coefficient and electrical resistivity at room temperature is reported. The novel aspect of this apparatus is the use of 4 multifunctional probes that comprise a junction of two conductors at the tip and serve as both thermocouples and electrical contacts. In addition, one of the probes has a built-in heater that can establish a temperature gradient in the sample for the Seebeck measurement. The technique does not require special sample geometries or preparation of contacts and is suitable for bulk and thin film materials. Together with automated sample stage and data acquisition, the equipment is able to measure both the Seebeck coefficient and electrical resistivity in less than 20 s with good accuracy. Less than 5% and 4% relative errors were found for the measurement of the Seebeck coefficient and electrical resistivity, respectively. This makes the apparatus especially useful for high throughput evaluation of thermoelectric materials.

  4. AC Electrokinetics of Physiological Fluids for Biomedical Applications.

    PubMed

    Lu, Yi; Liu, Tingting; Lamanda, Ariana C; Sin, Mandy L Y; Gau, Vincent; Liao, Joseph C; Wong, Pak Kin

    2015-12-01

    Alternating current (AC) electrokinetics is a collection of processes for manipulating bulk fluid mass and embedded objects with AC electric fields. The ability of AC electrokinetics to implement the major microfluidic operations, such as pumping, mixing, concentration, and separation, makes it possible to develop integrated systems for clinical diagnostics in nontraditional health care settings. The high conductivity of physiological fluids presents new challenges and opportunities for AC electrokinetics-based diagnostic systems. In this review, AC electrokinetic phenomena in conductive physiological fluids are described followed by a review of the basic microfluidic operations and the recent biomedical applications of AC electrokinetics. The future prospects of AC electrokinetics for clinical diagnostics are presented.

  5. AC Electrokinetics of Physiological Fluids for Biomedical Applications

    PubMed Central

    Lu, Yi; Liu, Tingting; Lamanda, Ariana C.; Sin, Mandy L Y; Gau, Vincent; Liao, Joseph C.; Wong, Pak Kin

    2016-01-01

    AC electrokinetics is a collection of processes for manipulating bulk fluid mass and embedded objects with AC electric fields. The ability of AC electrokinetics to implement the major microfluidic operations, such as pumping, mixing, concentration and separation, makes it possible to develop integrated systems for clinical diagnostics in non-traditional healthcare settings. The high conductivity of physiological fluids presents new challenges and opportunities for AC electrokinetics based diagnostic systems. In this review, AC electrokinetic phenomena in conductive physiological fluids are described followed by a review of the basic microfluidic operations and the recent biomedical applications of AC electrokinetics. The future prospects of AC electrokinetics for clinical diagnostics are presented. PMID:25487557

  6. Challenges of Electrical Measurements of Advanced Gate Dielectrics in Metal-Oxide-Semiconductor Devices

    NASA Astrophysics Data System (ADS)

    Vogel, Eric M.; Brown, George A.

    2003-09-01

    Experimental measurements and simulations are used to provide an overview of key issues with the electrical characterization of metal-oxide-semiconductor (MOS) devices with ultra-thin oxide and alternate gate dielectrics. Experimental issues associated with the most common electrical characterization method, capacitance-voltage (C-V), are first described. Issues associated with equivalent oxide thickness extraction and comparison, interface state measurement, extrinsic defects, and defect generation are then overviewed.

  7. Measurement of electric field and gradient in the plasma sheath using clusters of floating microspheres

    SciTech Connect

    Sheridan, T. E.; Katschke, M. R.; Wells, K. D.

    2007-02-15

    A method for measuring the time-averaged vertical electric field and its gradient in the plasma sheath using clusters with n=2 or 3 floating microspheres of known mass is described. The particle charge q is found by determining the ratio of the breathing frequency to the center-of-mass frequency for horizontal (in-plane) oscillations. The electric field at the position of the particles is then calculated using the measured charge-to-mass ratio, and the electric-field gradient is determined from the vertical resonance frequency. The Debye length is also found. Experimental results are in agreement with a simple sheath model.

  8. Electric field measurement in the ionosphere using the time-of-flight technique

    SciTech Connect

    Nakamura, Masato; Hayakawa, Hajime; Tsuruda, Koichiro )

    1989-05-01

    The first successful electric field measurement in the ionosphere using the time-of-flight technique with a lithium ion beam was carried out on a S-520 sounding rocket launched from Kagoshima Space Center, Japan on January 15, 1987. The purpose of this experiment was to prove the validity of the time-of-flight technique when it is applied to the measurement of the dc electric field in the ionosphere. A time-coded ion beam was ejected from the rocket in the direction perpendicular to the Earth's magnetic field. The beam returned to the rocket twice per rocket spin when the initial beam direction was nearly perpendicular to the electric field. The electric field and the magnetic field were derived from the travel time of these return lithium ions. The accuracy of the electric field determination was {plus minus} 0.3 mV/m. The direction of the electric field was obtained from the direction of the returning ion beam after about one ion gyration. The main constituent of the measured electric field was a V {times} B field due to the rocket motion across the geomagnetic field. The ambient field was less than 1 mV/m. The magnetic field was measured with an accuracy of {plus minus} 2.7 nT in this experiment.

  9. 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.

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

    NASA Astrophysics Data System (ADS)

    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.

  11. In-Vivo Techniques for Measuring Electrical Properties of Tissues.

    DTIC Science & Technology

    1980-09-01

    of a 16-guage hypodermic needle . In-situ dielectric measurements of both living and non-living canine brain were performed on the dura, on the pia...ensure their proper performance and measurement accuracy. The use of a stainless steel hypodermic needle as the outer conductor of the probe provided...fabrication, the design of special coaxial probes, (with the outer conductor being effectively a hypodermic needle ), and the design tooling, and

  12. Surface Roughness Influence on Eddy Current Electrical Conductivity Measurements

    DTIC Science & Technology

    2003-01-01

    presented on shot peened pure ( C11000 ) copper , in which the effect is particularly stro n g and readily measurable because of the low penetration depth...electri- cal conductivity measurements were carried out on each fully relaxed shot peened copper specimen over a wide frequency range from 1 kHz to...residual stress is created over a shallow surface layer. Shot peening is performed on a wide range of materials, including gas turbine engine components

  13. A two electrode apparatus for electrical impedance measurements

    NASA Astrophysics Data System (ADS)

    Merriam, J. B.

    2009-12-01

    A two electrode cell for complex impedance measurements on core samples in the range 1 mHz - 0.3 kHz is described. Two electrode cells are more convenient than four electrode cells but some restrictions need to be observed. I will show that the contact impedance between the electrodes and the sample can be controlled and reduced to less than fifty ohms in most cases. The contact impedance is repeatable, with a peak phase near 10 Hz of less than one degree and a maximum change in impedance magnitude of less than fifty ohm. A model for the contact impedance is used to correct impedance measurements, leaving an un-modeled contact impedance of a few ohms. There is typically a drift of about 100 ohm during a measurement sequence due to diffusion between the ceramic frits at the ends of the sample. This is corrected by repeat measurements at 100 Hz. Un-modeled impedance changes due to drift are about ten ohm. The un-modeled impedance changes mean that the relative error on conductive samples is greater than on resistive samples. Repeat measurements on a sandstone sample with conductive pore water (0.14 S/m) yield a mean of 492 ohms with a standard deviation of 20 ohm, or about five percent. Measurements on mineralized core and on cells constructed from mixtures of silica sand and polarizable minerals demonstrate that the two electrode set up can be used even on heavily mineralized samples.

  14. Identification of alternating renewal electric load models from energy measurements

    NASA Astrophysics Data System (ADS)

    El-Ferik, Sami; Malhame, Roland P.

    1994-06-01

    In statistical load modeling methodologies, aggregate electric load behavior is derived by propagating the ensemble statistics of an individual load process which is representative of the loads in the aggregate. Such a modeling philosophy tends to yield models whereby if physical meaning is present at the elemental level, it is preserved at the aggregate level. This property is essential for applications involving direct control of power system loads (for peak load shaving purposes, for example). The potential applicability of statistical load models is a strong function of one's ability to limit the volume of unusual data required to build those. An identification algorithm for a previously proposed stochastic hybrid-state Markov model of individual heating-cooling loads is presented. It relies only on data routinely gathered in power systems (device energy consumption over constant time intervals). It exploits an alternating renewal viewpoint of the load dynamics. After deriving some general results on the occupation statistics of time homogeneous alternating renewal processes, the analysis is focused on the specific model. In the process, however, some intriguing features likely to be shared by a wide class of alternating renewal processes are revealed.

  15. Specification, Measurement, and Control of Electrical Switching Transients

    NASA Technical Reports Server (NTRS)

    Javor, K.

    1999-01-01

    There have been several instances of susceptibility to switching transients. The Space Shuttle Spacelab Remote Acquisition Unit (RAU-A standard interface between Spacelab payloads and the Shuttle communications system) will shut down if the input 28 Vdc bus drops below 22 volts for more than 80 gs. Although a MIL-STD-461 derivative CS06 requirement was levied on the RAU, it failed to find this susceptibility. A heavy payload on one aircraft sags the 28 volt bus below 20 volts for milliseconds. Dc-dc converters have an operating voltage. A typical 28 Vdc-to-5 Vdc converter operates within tolerance when input potential is between 17-40 Vdc, A hold-up capacitor can be used to extend the time this range is presented to the convener when the line potential sags or surges outside this range. The designer must know the range of normal transients in order to choose the correct value of hold-up. This report describes the phenomena of electrical power bus transients induced by the switching of loads both on and off the bus, and control thereof.

  16. Hydrostatic Pressure Study on 3-K Phase Superconductivity in Sr2RuO4-Ru Eutectic Crystals by AC Magnetic Susceptibility Measurements

    NASA Astrophysics Data System (ADS)

    Yaguchi, Hiroshi; Watanabe, Hiromichi; Sakaue, Akira

    2012-12-01

    We have investigated the effect of hydrostatic pressure on 3-K phase superconductivity in Sr2RuO4-Ru eutectic crystals by means of AC magnetic susceptibility measurements. We have found that the application of hydrostatic pressure suppresses the superconducting transition temperature Tc of the 3-K phase with a pressure coefficient of dTc/dP ≈ -0.2 K/GPa, similar to the case of the 1.5-K phase. We have also observed that the effect of hydrostatic pressure on the 3-K phase seems to be elastic whilst that of uniaxial pressure is plastic.

  17. Microstructure, AC impedance and DC electrical conductivity characteristics of NiFe2-xGdxO4 (x = 0, 0.05 and 0.075)

    NASA Astrophysics Data System (ADS)

    Kamala Bharathi, K.; Markandeyulu, G.; Ramana, C. V.

    2012-03-01

    The structure and electrical characteristics of Gd doped Ni ferrite materials, namely NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4, are reported to demonstrate their improved electrical properties compared to that of pure NiFe2O4. NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds crystallize in the cubic inverse spinel phase with a very small amount of GdFeO3 additional phase while pure NiFe2O4 crystallize in inverse spinel phase without any impurity phase. The back scattered electron imaging analysis indicate the primary and secondary formation in NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds. Atomic force microscopy measurements indicate that the bulk grains are ˜2-5 micron size while the grain boundaries are thin compared to bulk grains. Impedance spectroscopic analysis at different temperature indicates the different relaxation mechanisms and their variation with temperature, bulk grain and grain-boundary contributions to the electrical conductivity (Rg) and capacitance (Cg) of these materials. The conductivity in pure NiFeO4 is found to be predominantly due to intrinsic bulk contribution (Rg=213 kΩ and Cg=4.5 x 10-8 F). In the case of NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds, grain and grain-boundary contributions to the conductivity are clearly observed. The DC conductivity values (at 300 K) of NiFe2O4, NiFe1.95Gd0.05O4 and NiFe1.925Gd0.075O4 compounds are found to be 1.06 x 10-7 Ω-1 cm-1, 5.73 x 10-8 Ω-1 cm-1 and 1.28 x 10-8 Ω-1 cm-1 respectively.

  18. Simultaneous Measurement of Elastic and Electrical Anisotropy of Shales under Elevated Pressure: A Preliminary Study

    NASA Astrophysics Data System (ADS)

    Ou, L.; Niu, Q.; Prasad, M.

    2015-12-01

    Low-porosity shales are generally considered as transverse isotropic (TI) material, both elastically and electrically. We explore the correlation of elastic and electrical anisotropy of shales to mineralogy and organic richness. Both, elastic and electrical anisotropies in rocks are known to be functions of clay and kerogen contents. The elastic anisotropy in clay- and organic-rich shales is related to their laminated and lenticular texture that is enhanced with compaction and diagenesis leading. The correlation of complex resistivity and anisotropy in shales with clay content has theoretically modeled using cation exchange capacity of the clay minerals. Although, it is appear likely that elastic and electrical anisotropy might be controlled by similar petrophyiscal properties, very little research exists that explores the relationship between these two anisotropies and how petrophysical properties might influence them. We present an experimental data of elastic and electrical anisotropy in shales acquired with a new system that allows simultaneous measurements of acoustic velocities and complex resistivities under hydrostatic pressure in three directions: parallel, 45° and perpendicular to any orientation, such as bedding planes. Our results of five shale samples show: Elastic and electrical anisotropy are inversely related to pressure Electrical anisotropy is generally higher than elastic anisotropy Electrical anisotropy is more sensitive to pressure change Complex resistivity anisotropy for in-phase resistivity and phase is highly frequency dependent In future, we plan to measure shale samples with varying clay and organic contents and correlate anisotropy to petrophysical properties.

  19. Positive dielectrophoresis and aggregation in suspensions of highly polarized particles subjected to high-gradient AC electric fields in macro-scale flow and microfluidics

    NASA Astrophysics Data System (ADS)

    Acrivos, Andreas; Qiu, Zhiyong; Khusid, Boris; Markarian, Nikolai

    2001-11-01

    The recent surge of activity in the area of electro-hydrodynamics of suspensions subjected to strong electric fields ( several kV/mm) is motivated not only by scientific curiosity but also by numerous technological applications from separation to filtration to microfluidics. We will present the results of theoretical and experimental studies of particle motions and segregation in a suspension subjected to high-gradient strong fields and shear. To study macro-scale electro-hydrodynamic phenomena in suspensions of highly polarized, heavy particles, we developed a setup in which a suspension flows through a channel rotating around a horizontal axis along with a special technique to energize the electrodes. At the rotation speed of several tens rpm, the buoyancy force averaged over the period of rotation equals zero whereas the centrifugal force appears to be negligibly small. Next we fabricated several electro-hydrodynamic microfluidics, each consisting of silicon and glass wafers bonded together and containing an array of 174 individually operated electric chambers (6 mm in length with the 3 mm X 30 um cross-section). These chambers are equipped with electrodes having the thickness of 2-um, 5-um, and 10-um. We found that the particle behavior in micro- and macro-flows appears to be quite similar and can be predicted by our theoretical models. The work was supported in parts by grants from NASA, the Office of Naval Research, and the New Jersey Commission on Science & Technology MEMS Initiative. The measurements of the suspension complex dielectric permittivity and the particle size distribution were conducted using the instrumentation of the NJIT W.M. Keck Foundation Laboratory for Electro-hydrodynamics of Suspensions.

  20. In situ measurements of contributions to the global electrical circuit by a thunderstorm in southeastern Brazil

    USGS Publications Warehouse

    Thomas, J.N.; Holzworth, R.H.; McCarthy, M.P.

    2009-01-01

    The global electrical circuit, which maintains a potential of about 280??kV between the earth and the ionosphere, is thought to be driven mainly by thunderstorms and lightning. However, very few in situ measurements of electrical current above thunderstorms have been successfully obtained. In this paper, we present dc to very low frequency electric fields and atmospheric conductivity measured in the stratosphere (30-35??km altitude) above an active thunderstorm in southeastern Brazil. From these measurements, we estimate the mean quasi-static conduction current during the storm period to be 2.5 ?? 1.25??A. Additionally, we examine the transient conduction currents following a large positive cloud-to-ground (+ CG) lightning flash and typical - CG flashes. We find that the majority of the total current is attributed to the quasi-static thundercloud charge, rather than lightning, which supports the classical Wilson model for the global electrical circuit.

  1. Slow crack growth measurement using an electrical grid

    NASA Technical Reports Server (NTRS)

    Martin, D. J.; Davido, K. W.; Scott, W. D.

    1986-01-01

    Photolithography was used to produce a resistance grid on the surface of a DCB fracture specimen. The grid line spacings were 10 microns over a distance of 2 cm. Slow crack growth was measured on soda-lime-silica glass. At low values of K(I) (0.3 to 0.4 MPa.sq r + m, increased. Equations are given for the design of grids. The grid technique could be used to measure very slow crack growth at high temperature with appropriate compatible metal-ceramic materials.

  2. Recommended Practice for Pressure Measurements and Calculation of Effective Pumping Speeds During Electric Propulsion Testing

    NASA Technical Reports Server (NTRS)

    Dankanich, John W.; Walker, Mitchell; Swiatek, Michael W.; Yim, John T.

    2013-01-01

    The electric propulsion community has been implored to establish and implement a set of universally applicable test standards during the research, development, and qualification of electric propulsion systems. Variability between facility-to-facility and more importantly ground-to-flight performance can result in large margins in application or aversion to mission infusion. Performance measurements and life testing under appropriate conditions can be costly and lengthy. Measurement practices must be consistent, accurate, and repeatable. Additionally, the measurements must be universally transportable across facilities throughout the development, qualification, spacecraft integration, and on-orbit performance. A recommended practice for making pressure measurements, pressure diagnostics, and calculating effective pumping speeds with justification is presented.

  3. Detecting Damage Using Electric Field Measurements: A Computational Sensitivity Study

    DTIC Science & Technology

    2014-02-06

    on a range or in the Physical Scale Model ( PSM ) environment, the smallest area of damage that is detectable would depend upon measurement...sensitivities or errors along with the ability to physically create small pieces of bare metal on the PSM model. Figure 6-4. Comparison of calculated

  4. Optical tomography of Kerr electro-optic measurements with axisymmetric electric field

    SciTech Connect

    Uestuendag, A.; Zahn, M.

    1996-12-31

    Dielectrics become birefringent (Kerr effect) when stressed by high electric fields so that incident linearly or circularly polarized light propagating through the medium becomes elliptically polarized. Most past experimental work has been limited to cases where the electric field magnitude and direction have been constant along the light path, while recent analysis and point/plane electrode measurements have developed the Abel transformation which describes Kerr effect measurements when an axisymmetric electric field has magnitude but not direction varying along the light path. The present work develops the governing Kerr effect differential equations for an axisymmetric electric field for the case when both magnitude and direction vary along the light path. The specific case of point/plane electrodes are studied where analytical electric field solutions are used for the space charge free case and finite element computer analyses are used to calculate the electric field distribution for postulated space charge injection from the point electrode. The authors then calculate the Kerr electro optic fringe patterns that would result. They use the onion peeling method previously used for photoelastic analysis to calculate the electric field magnitude and direction from computer-simulated optical measurements.

  5. The use of electrical anisotropy measurements to monitor soil crack dynamics - laboratory evaluation

    NASA Astrophysics Data System (ADS)

    Sahraei, Amirhossein; Huisman, Johan Alexander; Zimmermann, Egon; Vereecken, Harry

    2016-04-01

    Swelling and shrinking of soil cracks is a key factor determining water fluxes in many irrigated soils. Most previous studies have used time-intensive and destructive methods for crack characterization, such as depth and volume determination from simplified geometrical measurements or liquid latex filling. Because of their destructive and time-consuming nature, these methods have only provided instantaneous estimates of the geometry and/or volume of cracks. The aim of this study is to evaluate the use of anisotropy in electrical resistivity measured with a square electrode array to determine crack depth dynamics. In a first step, the performance of the method was analyzed using a laboratory experiment where an artificial soil crack was emulated using a plastic plate in a water bath. Since cracking depth was precisely known, this experiment allowed to develop a method to estimate soil crack depth from measurements of the electrical anisotropy. In a second step, electrical anisotropy was measured during soil crack development within a soil monolith consisting of a mix of sand and bentonite. The cracking depth estimated from electrical measurement compared well with reference ruler measurements. These laboratory measurements inspired confidence in the use of electrical anisotropy for soil crack investigations, and consequently the developed methods will be applied to investigate soil crack dynamics in the field in a next step.

  6. A new technique to determine the lightning charge location from the electric field vector measurements

    NASA Astrophysics Data System (ADS)

    Ravichandran, M.; Kamra, A. K.

    2004-03-01

    A new technique to find out the magnitude and location of the net charge center and the charge destroyed in a lightning flash in a thundercloud has been proposed. The technique is based on the measurements of the electric field vector on the ground surface during a lightning flash. The technique has the advantage of field measurements being made at only one station if simultaneous measurements for the distance of lightning are made with time-to-thunder technique. From our measurements made with a spherical field meter with Maxwell's current density, typical cases of cloud-to-cloud and cloud-to-ground discharges are analyzed. The values of above parameters calculated from this technique are within the normal range of these variables in thunderclouds inferred from other techniques. However, the charge values show significant change when the electric field vector instead of only the vertical electric field measured by conventional field mill is used for the calculations.

  7. A Novel Method for Measuring Electrical Conductivity of High Insulating Oil Using Charge Decay

    NASA Astrophysics Data System (ADS)

    Wang, Z. Q.; Qi, P.; Wang, D. S.; Wang, Y. D.; Zhou, W.

    2016-05-01

    For the high insulating oil, it is difficult to measure the conductivity precisely using voltammetry method. A high-precision measurementis proposed for measuring bulk electrical conductivity of high insulating oils (about 10-9--10-15S/m) using charge decay. The oil is insulated and charged firstly, and then grounded fully. During the experimental procedure, charge decay is observed to show an exponential law according to "Ohm" theory. The data of time dependence of charge density is automatically recorded using an ADAS and a computer. Relaxation time constant is fitted from the data using Gnuplot software. The electrical conductivity is calculated using relaxation time constant and dielectric permittivity. Charge density is substituted by electric potential, considering charge density is difficult to measure. The conductivity of five kinds of oils is measured. Using this method, the conductivity of diesel oil is easily measured to beas low as 0.961 pS/m, as shown in Fig. 5.

  8. Electrical impedance measurements: rapid method for detecting and monitoring microorganisms.

    PubMed Central

    Cady, P; Dufour, S W; Shaw, J; Kraeger, S J

    1978-01-01

    A conceptually simple and east-to-use technique is described that uses continuous impedance measurements for automated monitoring of microbial growth and metabolism. The method has been applied to a wide range of microorganisms. Optical clarity is not required. The sensitivity and reproducibility of the method are demonstrated. The mechanism whereby microbial growth alters the impedance of the medium is discussed, as well as potential applications of the method to clinical microbiology. Images PMID:348718

  9. Measurements of Electrical Transport Phenomena in Semiconductor Materials.

    DTIC Science & Technology

    1981-11-01

    equivalent circuit for microwave time-of-flight measurements. 158 xiii 5.2 a) Simplified equivalent circuit . b) Circuit ...process. 219 C.1 Microwave C-V technique. a) Experimental configuration. b) Equivalent circuit for (a). 223 D.1 Test configurations for beam profiling and X...reference point and ,rrors in the quantities W, i, and 4. 5.2. Circuit Effects In this section we present an equivalent circuit model for the

  10. 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.

  11. Electronmagnetic induction probe calibration for electrical conductivity measurements and moisture content determination of Hanford high level waste

    SciTech Connect

    Wittekind, W.D., Westinghouse Hanford

    1996-05-23

    Logic of converting EMI measured electrical conductivity to moisture with expected uncertainty. Estimates from present knowledge, assumptions, and measured data. Archie`s Law has been used since the 1940`s to relate electrical conductivity in porous media to liquid volume fraction. Measured electrical conductivity to moisture content uses: Porosity, Interstitial liquid electrical conductivity, Solid particle density,Interstitial liquid density, and interstitial liquid water content. The uncertainty of assumed values is calculated to determine the final moisture wt.% result uncertainty.

  12. Hy-wire and fast electric field change measurements near an isolated thunderstorm, appendix C

    NASA Technical Reports Server (NTRS)

    Holzworth, R. H.; Levine, D. M.

    1983-01-01

    Electric field measurements near an isolated thunderstorm at 6.4 km distance are presented from both a tethered balloon experiment called Hy-wire and also from ground based fast and slow electric field change systems. Simultaneous measurements were made of the electric fields during several lightning flashes at the beginning of the storm which the data clearly indicate were cloud-to-ground flashes. In addition to providing a comparison between the Hy-wire technique for measuring electric fields and more traditional methods, these data are interesting because the lightning flashes occurred prior to changes in the dc electric field, although Hy-wire measured changes in the dc field of up to 750 V/m in the direction opposite to the fair weather field a short time later. Also, the dc electric field was observed to decay back to its preflash value after each flash. The data suggest that Hy-wire was at the field reversal distance from this storm and suggest the charge realignment was taking place in the cloud with a time constant on the order of 20 seconds.

  13. Thermal Electrical, and Physical Property Measurements of Laser Window Materials

    DTIC Science & Technology

    1975-04-01

    PAGZ• I I I I -0-1 v -0mh TABLE OF CONTENTS (cort’d) Page 3. 1.7 Grain Boundary Effects in CdTe ......... 97 3. 1.8 A Proposed Grain Boundary Mode. for...95 31 Grain Boundary Resistance Measurements of a Tyco CdTe Ilicrystal ............ ................ 98 32 Grain Boundary ...8217,,iii LIST OF ILLUSTRATIONS (cont’d) Figure Page 35 Photoresponse Scans of Polycrystalline Tyco 74 CdTe .,. 104 3, Dislocation Model of a Grain Boundary

  14. Total AC loss characteristics of untwisted and twisted Bi-2223 multifilamentary tapes and interaction between self and external magnetic fields

    NASA Astrophysics Data System (ADS)

    Jiang, Zhenan; Amemiya, Naoyuki; Ayai, Naoki; Hayashi, Kazuhiko

    2004-11-01

    The authors have electrically measured the total AC losses of untwisted and twisted Bi-2223 multifilamentary tapes in AC parallel and perpendicular transverse magnetic fields. The magnetization and transport losses in the untwisted and twisted Bi-2223 multifilamentary tapes carrying an AC transport current in AC parallel and perpendicular transverse magnetic fields were measured independently to obtain the total AC loss. The total AC losses of both the untwisted and twisted Bi-2223 multifilamentary tapes in a parallel transverse magnetic field are approximately equal to the sum of the transport loss without the external magnetic field and the magnetization loss without the transport current. In particular, the total AC loss of the twisted tape in a parallel transverse magnetic field is in good agreement with this sum. On the other hand, the total AC losses of both the untwisted and twisted Bi-2223 multifilamentary tapes in a perpendicular transverse magnetic field are larger than the sum of the transport loss without any external magnetic field and the magnetization loss without transport current. The total AC loss of the twisted tape in a parallel transverse magnetic field can be predicted by the sum of the magnetization loss using the slab model for an equivalent filament thickness and the transport loss given by Norris for a superconductor with an elliptical cross section.

  15. Analysis of variance on thickness and electrical conductivity measurements of carbon nanotube thin films

    NASA Astrophysics Data System (ADS)

    Li, Min-Yang; Yang, Mingchia; Vargas, Emily; Neff, Kyle; Vanli, Arda; Liang, Richard

    2016-09-01

    One of the major challenges towards controlling the transfer of electrical and mechanical properties of nanotubes into nanocomposites is the lack of adequate measurement systems to quantify the variations in bulk properties while the nanotubes were used as the reinforcement material. In this study, we conducted one-way analysis of variance (ANOVA) on thickness and conductivity measurements. By analyzing the data collected from both experienced and inexperienced operators, we found some operation details users might overlook that resulted in variations, since conductivity measurements of CNT thin films are very sensitive to thickness measurements. In addition, we demonstrated how issues in measurements damaged samples and limited the number of replications resulting in large variations in the electrical conductivity measurement results. Based on this study, we proposed a faster, more reliable approach to measure the thickness of CNT thin films that operators can follow to make these measurement processes less dependent on operator skills.

  16. Electrical conductivity measurements of bacterial nanowires from Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Maruthupandy, Muthusamy; Anand, Muthusamy; Maduraiveeran, Govindhan; Sait Hameedha Beevi, Akbar; Jeeva Priya, Radhakrishnan

    2015-12-01

    The extracellular appendages of bacteria (flagella) that transfer electrons to electrodes are called bacterial nanowires. This study focuses on the isolation and separation of nanowires that are attached via Pseudomonas aeruginosa bacterial culture. The size and roughness of separated nanowires were measured using transmission electron microscopy (TEM) and atomic force microscopy (AFM), respectively. The obtained bacterial nanowires indicated a clear image of bacterial nanowires measuring 16 nm in diameter. The formation of bacterial nanowires was confirmed by microscopic studies (AFM and TEM) and the conductivity nature of bacterial nanowire was investigated by electrochemical techniques. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), which are nondestructive voltammetry techniques, suggest that bacterial nanowires could be the source of electrons—which may be used in various applications, for example, microbial fuel cells, biosensors, organic solar cells, and bioelectronic devices. Routine analysis of electron transfer between bacterial nanowires and the electrode was performed, providing insight into the extracellular electron transfer (EET) to the electrode. CV revealed the catalytic electron transferability of bacterial nanowires and electrodes and showed excellent redox activities. CV and EIS studies showed that bacterial nanowires can charge the surface by producing and storing sufficient electrons, behave as a capacitor, and have features consistent with EET. Finally, electrochemical studies confirmed the development of bacterial nanowires with EET. This study suggests that bacterial nanowires can be used to fabricate biomolecular sensors and nanoelectronic devices.

  17. AC-Susceptibility and Ultrasonic Attenuation Measurements of Vortex Dynamics in the Vicinity of the Peak Effect in V-Ti Alloys - Multicriticality Revisited

    NASA Astrophysics Data System (ADS)

    Dimitrov, I. K.

    2005-03-01

    In-situ SANS and ac-susceptibility measurements have provided evidence for a first-order Bragg glass transition into a disordered vortex state in a Nb single crystal. This transition manifests itself in the peak effect (PE) in the critical current density, widely believed to be associated with the sudden softening of the vortex lattice. Subsequent studies mapping the full phase diagram in the same sample have suggested the existence of four distinct phase boundaries meeting at a single multicritical point (MCP). The natures of the transition lines combined with simple thermodynamic requirements suggest that the MCP is a bicritical point. This would rule out either the bulk transition line Tc2(T) or the surface superconducting transition Hc3(T) as being related to the MCP. Mutual inductance magnetic ac-susceptibility and ultrasonic attenuation measurements in V-21at.%Ti have unequivocally established the presence of a PE in this alloy. The H-T phase diagram for this sample will be presented and vortex dynamics in the vicinity of the PE will be discussed. We are indebted to Prof. Shapira of Tufts University for providing us with the sample. This work was supported by the NSF under Grant No. DMR-0406626.

  18. Roebel assembled coated conductor cables (RACC): Ac-Losses and current carrying potential

    NASA Astrophysics Data System (ADS)

    Frank, A.; Heller, R.; Goldacker, W.; Kling, A.; Schmidt, C.

    2008-02-01

    Low ac-loss HTS cables for transport currents well above 1 kA are required for application in transformers and generators and are taken into consideration for future generations of fusion reactor coils. Coated conductors (CC) are suitable candidates for high field application at an operation temperature in the range 50-77 K. Ac-field applications require cables with low ac-losses and hence twisting of the individual strands. We solved this problem using the Roebel technique. Short lengths of Roebel bar cables were prepared from industrial DyBCO and YBCO-CC. Meander shaped tapes of 4 or 5 mm width with twist pitches of 123 or 127 mm were cut from the 10 or 12 mm wide CC tapes using a specially designed tool. Eleven or twelve of these strands were assembled to a cable. The electrical and mechanical connection of the tapes was achieved using a silver powder filled conductive epoxy resin. Ac-losses of a short sample in an external ac-field were measured as a function of frequency and field amplitude as well as the coupling current decay time constant. We discuss the results in terms of available theories and compare measured time constants in transverse field with measured coupling losses. Finally the potential of this cable type for ac-use is discussed with respect to ac-losses and current carrying capability.

  19. Detection of Rooftop Cooling Unit Faults Based on Electrical Measurements

    SciTech Connect

    Armstrong, Peter R.; Laughman, C R.; Leeb, S B.; Norford, L K.

    2006-01-31

    Non-intrusive load monitoring (NILM) is accomplished by sampling voltage and current at high rates and reducing the resulting start transients or harmonic contents to concise ''signatures''. Changes in these signatures can be used to detect, and in many cases directly diagnose, equipment and component faults associated with roof-top cooling units. Use of the NILM for fault detection and diagnosis (FDD) is important because (1) it complements other FDD schemes that are based on thermo-fluid sensors and analyses and (2) it is minimally intrusive (one measuring point in the relatively protected confines of the control panel) and therefore inherently reliable. This paper describes changes in the power signatures of fans and compressors that were found, experimentally and theoretically, to be useful for fault detection.

  20. [Comprehensive evaluation of protective measures in electric welding].

    PubMed

    Ye, K; Zhao, Z

    1995-03-01

    Protective effects of safety masks, eyewear, work clothes, gloves, periodically physical examination system, and ventilation and barriers at workplace, were evaluated by one-way analysis for handtorch welding, carbon dioxide gas-protective welding, and argon-arc welding operations, etc. in township and village enterprises and state-owned enterprises by interviewing managers in the departments of technology and work safety and field investigating. Based on the results of one-way analysis of protective measures, comprehensive evaluations of various enterprises were made with a fussy mathematical model. Both enterprises in township and village level and of state-owned were graded as A on a basis of the evaluation, which will be helpful to the better management of occupational health in the future.

  1. Considerations on electrical impedance measurements of electrolyte solutions in a four-electrode cell

    NASA Astrophysics Data System (ADS)

    Chaparro, C. V.; Herrera, L. V.; Meléndez, A. M.; Miranda, D. A.

    2016-02-01

    A tetrapolar probe to measure the electrical properties of electrolyte solutions was implemented with gold electrodes according to the van der Pauw method. Electrical impedance spectroscopy (EIS) measurements of different concentrations of phosphate buffer saline (PBS) solution and an oral mucosal tissue sample dispersed in PBS were performed in the galvanostatic mode using a four-electrode cell (tetrapolar probe). Taking advantage of using a potentiostat/galvanostat for carrying out the electrical measurements, a simple and rapid method using a three-electrode electrochemical cell is described for: a) cleaning of electrodes, b) verification of surface chemical state of electrode material and c) choice of current supplied to electrodes for EIS measurements. Results of this research shown a depolarization effect due to the addition of oral mucosa tissue cells into the PBS solution.

  2. A comparison of modeled and measured energy use in hybrid electric vehicles

    NASA Astrophysics Data System (ADS)

    Cuddy, Matthew

    1995-01-01

    CarSim 2.5.4, written by AeroVironment, Inc. of Monrovia, California and SIMPLEV 3.0, written by Idaho National Engineering Laboratory were used to simulate two series-configured hybrid electric vehicles that competed in the 1994 Hybrid Electric Vehicle Challenge. Vehicle speed and battery energy use were measured over a 0.2-km maximum effort acceleration and a 58-km range event. The simulations' predictions are compared to each other and to measured data. A rough uncertainty analysis of the validation is presented. The programs agree with each other to within 5% and with the measured energy data within the uncertainty of the experiment.

  3. Global Electric Circuit Implications of Combined Aircraft Storm Electric Current Measurements and Satellite-Based Diurnal Lightning Statistics

    NASA Technical Reports Server (NTRS)

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

    2011-01-01

    Using rotating vane electric field mills and Gerdien capacitors, we measured the electric field profile and conductivity during 850 overflights of thunderstorms and electrified shower clouds (ESCs) spanning regions including the Southeastern United States, the Western Atlantic Ocean, the Gulf of Mexico, Central America and adjacent oceans, Central Brazil, and the South Pacific. The overflights include storms over land and ocean, and with positive and negative fields above the storms. Over three-quarters (78%) of the land storms had detectable lightning, while less than half (43%) of the oceanic storms had lightning. Integrating our electric field and conductivity data, we determined total conduction currents and flash rates for each overpass. With knowledge of the storm location (land or ocean) and type (with or without lightning), we determine the mean currents by location and type. The mean current for ocean thunderstorms is 1.7 A while the mean current for land thunderstorms is 1.0 A. The mean current for ocean ESCs 0.41 A and the mean current for land ESCs is 0.13 A. We did not find any significant regional or latitudinal based patterns in our total conduction currents. By combining the aircraft derived storm currents and flash rates with diurnal flash rate statistics derived from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) low Earth orbiting satellites, we reproduce the diurnal variation in the global electric circuit (i.e., the Carnegie curve) to within 4% for all but two short periods of time. The agreement with the Carnegie curve was obtained without any tuning or adjustment of the satellite or aircraft data. Given our data and assumptions, mean contributions to the global electric circuit are 1.1 kA (land) and 0.7 kA (ocean) from thunderstorms, and 0.22 kA (ocean) and 0.04 (land) from ESCs, resulting in a mean total conduction current estimate for the global electric circuit of 2.0 kA. Mean storm counts are 1100 for land

  4. Global Electric Circuit Implications of Combined Aircraft Storm Electric Current Measurements and Satellite-Based Diurnal Lightning Statistics

    NASA Astrophysics Data System (ADS)

    Mach, D. M.; Blakeslee, R.; Bateman, M. G.

    2010-12-01

    Using rotating vane electric field mills and Gerdien capacitors, we measured the electric field profile and conductivity during 850 overflights of thunderstorms and electrified shower clouds (ESCs) spanning regions including the Southeastern United States, the Western Atlantic Ocean, the Gulf of Mexico, Central America and adjacent oceans, Central Brazil, and the South Pacific. The overflights include storms over land and ocean, and with positive and negative fields above the storms. Over three-quarters (78%) of the land storms had detectable lightning, while less than half (43%) of the oceanic storms had lightning. Integrating our electric field and conductivity data, we determined total conduction currents and flash rates for each overpass. With knowledge of the storm location (land or ocean) and type (with or without lightning), we determine the mean currents by location and type. The mean current for ocean thunderstorms is 1.7 A while the mean current for land thunderstorms is 1.0 A. The mean current for ocean ESCs 0.41 A and the mean current for land ESCs is 0.13 A. We did not find any significant regional or latitudinal based patterns in our total conduction currents. By combining the aircraft derived storm currents and flash rates with diurnal flash rate statistics derived from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) low Earth orbiting satellites, we reproduce the diurnal variation in the global electric circuit (i.e., the Carnegie curve) to within 4% for all but two short periods of time. The agreement with the Carnegie curve was obtained without any tuning or adjustment of the satellite or aircraft data. Given our data and assumptions, mean contributions to the global electric circuit are 1.1 kA (land) and 0.7 kA (ocean) from thunderstorms, and 0.22 kA (ocean) and 0.04 (land) from ESCs, resulting in a mean total conduction current estimate for the global electric circuit of 2.0 kA. Mean storm counts are 1100 for land

  5. ac Stark shift measurements of the clock transition in cold Cs atoms: Scalar and tensor light shifts of the D2 transition

    NASA Astrophysics Data System (ADS)

    Costanzo, G. A.; Micalizio, S.; Godone, A.; Camparo, J. C.; Levi, F.

    2016-06-01

    The ac Stark shift, or light shift, is a physical phenomenon that plays a fundamental role in many applications ranging from basic atomic physics to applied quantum electronics. Here, we discuss experiments testing light-shift theory in a cold-atom cesium fountain clock for the Cs D2 transition (i.e., 6 2S1 /2→6 2P3 /2 at 852 nm). Cold-atom fountains represent a nearly ideal system for the study of light shifts: (1) The atoms can be perturbed by a field of arbitrary character (e.g., coherent field or nonclassical field); (2) there are no trapping fields to complicate data interpretation; (3) the probed atoms are essentially motionless in their center-of-mass reference frame, T ˜ 1 μK; and (4) the atoms are in an essentially collisionless environment. Moreover, in the present work the resolution of the Cs excited-state hyperfine splittings implies that the D2 ac Stark shift contains a nonzero tensor polarizability contribution, which does not appear in vapor phase experiments due to Doppler broadening. Here, we test the linearity of the ac Stark shift with field intensity, and measure the light shift as a function of field frequency, generating a "light-shift curve." We have improved on the previous best test of theory by a factor of 2, and after subtracting the theoretical scalar light shift from the experimental light-shift curves, we have isolated and tested the tensor light shift for an alkali D2 transition.

  6. The future of GPS-based electric power system measurements, operation and control

    SciTech Connect

    Rizy, D.T.; Wilson, R.E.; Martin, K.E.; Litzenberger, W.H.; Hauer, J.F.; Overholt, P.N.; Sobajic, D.J.

    1998-11-01

    Much of modern society is powered by inexpensive and reliable electricity delivered by a complex and elaborate electric power network. Electrical utilities are currently using the Global Positioning System-NAVSTAR (GPS) timekeeping to improve the network`s reliability. Currently, GPS synchronizes the clocks on dynamic recorders and aids in post-mortem analysis of network disturbances. Two major projects have demonstrated the use of GPS-synchronized power system measurements. In 1992, the Electric Power Research Institute`s (EPRI) sponsored Phase Measurements Project used a commercially available Phasor Measurements Unit (PMU) to collect GPS-synchronized measurements for analyzing power system problems. In 1995, Bonneville Power Administration (BPA) and Western Area Power Administration (WAPA) under DOE`s and EPRI`s sponsorship launched the Wide Area Measurements (WAMS) project. WAMS demonstrated GPS-synchronized measurements over a large area of their power networks and demonstrated the networking of GPS-based measurement systems in BPA and WAPA. The phasor measurement technology has also been used to conduct dynamic power system tests. During these tests, a large dynamic resistor was inserted to simulate a small power system disturbance.

  7. Field-aligned electric currents and their measurement by the incoherent backscatter technique

    NASA Technical Reports Server (NTRS)

    Bauer, P.; Cole, K. D.; Lejeume, G.

    1975-01-01

    Field aligned electric currents flow in the magnetosphere in many situations of fundamental geophysical interest. It is shown here that the incoherent backscatter technique can be used to measure these currents when the plasma line can be observed. The technique provides a ground based means of measuring these currents which complements the rocket and satellite ones.

  8. Electrical Noise and the Measurement of Absolute Temperature, Boltzmann's Constant and Avogadro's Number.

    ERIC Educational Resources Information Center

    Ericson, T. J.

    1988-01-01

    Describes an apparatus capable of measuring absolute temperatures of a tungsten filament bulb up to normal running temperature and measuring Botzmann's constant to an accuracy of a few percent. Shows that electrical noise techniques are convenient to demonstrate how the concept of temperature is related to the micro- and macroscopic world. (CW)

  9. Measurement of Electrical Conductivity into Tomato Cultivation Beds using Small Insertion Type Electrical Conductivity Sensor Designed for Agriculture

    NASA Astrophysics Data System (ADS)

    Kawashima, Kazuko; Futagawa, Masato; Ban, Yoshihiro; Asano, Yoshiyuki; Sawada, Kazuaki

    Our group has studied on-site monitoring sensor for agricultural field. An electrical conductivity (EC) sensor had been fabricated using Si integrated circuit technology. EC information of solutions shows ion concentrations dissolving in water, and can be used as the index of nutrient concentration for plants. So, it is important to measure EC in real time and on site. Because our EC sensor (5mm×5mm in size) is smaller than other commercial ones (several centimeters), it is easy to insert and achieve measurement in rock wool. In this study, our sensor measured long term EC values in tomato cultivation soil and rock wool medium. At first, we calibrated a relationship between output voltages and EC values on the sensor. The sensor was confirmed about enough EC measurement range from 8 to 969mS/m. In long period measurement, the sensor was confirmed about continuous operation for over five months, and intermittent measurement for over a year. In measurement in the cultivation soil, the sensor indicated that water was kept and diffused in the soil. In contrast, it was found that water diffused without keeping in it in rock wool medium. We confirmed our small EC sensor is useful for on-site monitoring and analysis of solution concentration distribution in several kinds of cultivation bed in real time.

  10. Trapping polar molecules in an ac trap

    SciTech Connect

    Bethlem, Hendrick L.; Veldhoven, Jacqueline van; Schnell, Melanie; Meijer, Gerard

    2006-12-15

    Polar molecules in high-field seeking states cannot be trapped in static traps as Maxwell's equations do not allow a maximum of the electric field in free space. It is possible to generate an electric field that has a saddle point by superposing an inhomogeneous electric field to an homogeneous electric field. In such a field, molecules are focused along one direction, while being defocused along the other. By reversing the direction of the inhomogeneous electric field the focusing and defocusing directions are reversed. When the fields are being switched back and forth at the appropriate rate, this leads to a net focusing force in all directions. We describe possible electrode geometries for creating the desired fields and discuss their merits. Trapping of {sup 15}ND{sub 3} ammonia molecules in a cylindrically symmetric ac trap is demonstrated. We present measurements of the spatial distribution of the trapped cloud as a function of the settings of the trap and compare these to both a simple model assuming a linear force and to full three-dimensional simulations of the experiment. With the optimal settings, molecules within a phase-space volume of 270 mm{sup 3} (m/s){sup 3} remain trapped. This corresponds to a trap depth of about 5 mK and a trap volume of about 20 mm{sup 3}.

  11. An optical and electrical layered sensor for the measurement of ingredients in liquid

    NASA Astrophysics Data System (ADS)

    Kimoto, A.; Makisako, T.; Shida, K.

    2007-11-01

    In this paper, an electrical and optical layered sensor is proposed as a new, non-invasive sensing method for the measurement of ingredients in liquid, particularly in the food industry. In the proposed sensor, the optical properties of the liquid are measured by a light-emitting diode (LED) and a photodiode, and the electrical properties are measured by indium tin oxide (ITO) film electrodes with the transparent conductive properties arranged on the surfaces of the LED and the photodiode. Thus, the electrical and optical properties in the same space of the liquid can be simultaneously measured at a single sensor. To test the sensor experimentally, two parameters of a liquid—such as concentrations of red color and sodium chloride (NaCl) between 0.1% and 0.5% in distilled water—were estimated using measurement values of the electrical and optical properties obtained with the proposed sensor. In addition, it was found that two other parameters of a liquid, such as coffee and milk concentrations between 0.1% and 1.0% in distilled water, could also be estimated with the proposed sensor. The measurement values of optical properties with and without the ITO film and those of electrical properties using an ITO film electrode and a stainless-steel film electrode were also compared. The results suggested that it is possible to measure both optical and electrical properties using the proposed sensor, although there are still some problems such as the surface resistance and transmittance of the ITO film that must be addressed.

  12. Hydraulic Units Associated with Unconsolidated Sediments and Spectral Electrical Response Measurements.

    NASA Astrophysics Data System (ADS)

    Boadu, B.

    2004-12-01

    Knowledge of the hydraulic properties of unconsolidated materials (hydraulic conductivity, porosity) from non-invasive geophysical measurements is appealing to geoscientists involved in the hydrological characterization of the earth's subsurface. There is the need to understand the quantitative relationship between measurable geophysical attributes and hydraulic parameters of sediments or soils. Clustering sediments in hydraulic units help in relating parameters characterizing spectral electrical response (SER) measurements and hydraulic conductivity. The SER of soils is modeled with a multi-Cole-cole model considering soils as a heterogeneous multi-phase system. The validity and usefulness of the relations between the electrical parameters and the hydraulic units were assessed using laboratory measurements of the spectral electrical response(0.01Hz to 10 kHz) of over 30 soil samples with wide variability in physical properties. The soils are fully characterized: hydraulic conductivity, porosity, grain size distribution and moisture content of each soil sample were measured. The SER measurements are utilized to estimate the hydraulic unit characterizing the potential flow zones the soils. The intrinsic parameters, which describe the response of the model are retrieved by inversion schemes and are used in establishing the relations. Such relationships between parameters characterizing the spectral electrical response of soils and their hydraulic units may provide versatile and relaible non-invasive methodology of obtaining hydraulic properties information of soils from geophysical measurements.

  13. Starting Phenomena and Temperature-rise under vvvf Supply of Three-Phase Squirrel-Cage ac Traction Motor of Electric Locomotive

    NASA Astrophysics Data System (ADS)

    Paul, R. N.; Arya, L. D.; Verma, H. K.

    2012-09-01

    In three-phase squirrel-cage ac traction motor, temperature-rise calculation during variable-voltage and variable-frequency starting is of vital importance and has to be predicted and critically examined. Under voltage source inverter supply with PWM, the generation of harmonics by inverter supply reduces the output during starting due to higher harmonic losses, thereby reducing the starting tractive effort in kN on locomotive wheel. Stator and rotor temperature-rises during starting have been determined for average acceleration torque in segmental zone (calculated from variable acceleration) which have been presented in the paper with both copper and aluminium alloy rotor bars.

  14. Combined Aircraft and Satellite-Derived Storm Electric Current and Lightning Rates Measurements and Implications for the Global Electric Circuit

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

    Using rotating vane electric field mills and Gerdien capacitors, we measured the electric field profile and conductivity during 850 overflights of electrified shower clouds and thunderstorms spanning regions including the Southeastern United States, the Western Atlantic Ocean, the Gulf of Mexico, Central America and adjacent oceans, Central Brazil, and the South Pacific. The overflights include storms over land and ocean, with and without lightning, and with positive and negative fields above the storms. The measurements were made with the NASA ER-2 and the Altus-II high altitude aircrafts. Peak electric fields, with lightning transients removed, ranged from -1.0 kV/m to 16 kV/m, with a mean value of 0.9 kV/m. The median peak field was 0.29 kV/m. Integrating our electric field and conductivity data, we determined total conduction currents and flash rates for each overpass. With knowledge of the storm location (land or ocean) and type (with or without lightning), we determine the mean currents by location and type. The mean current for ocean storms with lightning is 1.6 A while the mean current for land storms with lightning is 1.0 A. The mean current for oceanic storms without lightning (i.e., electrified shower clouds) is 0.39 A and the mean current for land storms without lightning is 0.13 A. Thus, on average, land storms with or without lightning have about half the mean current as their corresponding oceanic storm counterparts. Over three-quarters (78%) of the land storms had detectable lightning, while less than half (43%) of the oceanic storms had lightning. We did not find any significant regional or latitudinal based patterns in our total conduction currents. By combining the aircraft derived storm currents and flash rates with diurnal lightning statistics derived from the Lightning Imaging Sensor (LIS) and Optical Transient Detector (OTD) low Earth orbiting satellites, we reproduce the diurnal variation in the global electric circuit (i.e., the Carnegie

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

    NASA Technical Reports Server (NTRS)

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

    2010-01-01

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

  16. Measurement technique of electric field using ultraviolet/visible spectroscopy in cylindrical plasmas

    SciTech Connect

    Kobayashi, T.; Yoshikawa, M.; Kubota, Y.; Saito, M.; Numada, M.; Ishii, K.; Cho, T.

    2004-10-01

    The rotation of impurity ion has been measured using ultraviolet (UV) visible spectroscopy in the cylindrical fusion plasma GAMMA 10 to investigate diamagnetic drift and ExB drift. The electric field is estimated with the plasma rotation and ExB drift analysis. Since the detected signal is the line integrated emission, the parametric Abel inversion technique has been developed. In the method, a density profile of impurity ion was assumed. Recently, we can obtain the density profile using collisional-radiative model (CRM) calculation. Then the electric field is obtained independently of that assumption. We present the measurement technique of the electric field using UV/visible spectroscopy and CRM calculation. The experimental result in GAMMA 10 is that consistent with the result of the neutral beam probe measurement.

  17. In situ measurements and radar observations of a severe storm - Electricity, kinematics, and precipitation

    NASA Technical Reports Server (NTRS)

    Byrne, G. J.; Few, A. A.; Stewart, M. F.; Conrad, A. C.; Torczon, R. L.

    1987-01-01

    Electric field measurements made inside a multicell severe storm in Oklahoma in 1983 with a balloon-borne instrument are presented. The properties of the electric charge regions, such as altitude, thickness, and charge concentrations, are studied. These measurements are analzyed with meteorological measurements of temperature and humidity, and balloon tracking and radar observations. The relation between the electric charge structure and the precipitation and kinematic features of the storm is examined. The data reveal that the cell exhibits a bipolar charge structure with negative charge below positive charge. The average charge concentrations of the two regions are estimated as -1.2 and 0.15 nC/cu m, respectively; the upper positive charge is about 6 km in vertical extent, and the lower negative charge is less than 1 km in vertical extent.

  18. Rock matrix diffusivity determinations by in-situ electrical conductivity measurements.

    PubMed

    Ohlsson, Y; Löfgren, M; Neretnieks, I

    2001-02-01

    A fast method to determine rock matrix diffusion properties directly in the bedrock would be valuable in the investigation of a possible site for disposal of nuclear waste. An "effective diffusivity borehole log" would provide important information on the variability of this entity over the area studied. As opposed to traditional matrix diffusion laboratory experiments, electrical conductivity measurements are fast, inexpensive and also easy to carry out in-situ. In this study, electrical resistivity data from borehole logging, as well as from measurements on the actual core, is evaluated with the purpose of extracting matrix diffusivity data. The influence of migration of ions in the electrical double layer, which can be of great importance in low ionic strength pore water, is also considered in evaluating the in-situ data to accurately determine the effective pore diffusivity. The in-situ data compare fairly well to those measured in the rock core.

  19. Plasma and electric field measurements of the PVO in the Venus ionosheath. [Pioneer Venus Orbiter

    NASA Technical Reports Server (NTRS)

    Perez-De-tejada, H.; Intriligator, D. S.; Scarf, F. L.

    1984-01-01

    A study of the plasma and electric-field measurements of the PVO in the Venus ionosheath near the terminator region is presented. A drastic decrease of the particle-flux intensity measured with the plasma instrument is encountered in the inner ionosheath before the inbound crossing of the ionopause. The outer boundary of the region of weak plasma fluxes is consistent with the presence of a rarefaction wave as reported previously from the Mariner 5 (Bridge et at., 1967), Venera (Verigin et al., 1978) and PVO (Spenner et al., 1980) plasma measurements in the Venus wake. Near that boundary there are, in addition, appreciable changes in the electric field signals detected with the PVO electric-field detectors. These observations suggest the existence of local plasma-wave activity associated with turbulent flow conditions in that region.

  20. On error sources during airborne measurements of the ambient electric field

    NASA Technical Reports Server (NTRS)

    Evteev, B. F.

    1991-01-01

    The principal sources of errors during airborne measurements of the ambient electric field and charge are addressed. Results of their analysis are presented for critical survey. It is demonstrated that the volume electric charge has to be accounted for during such measurements, that charge being generated at the airframe and wing surface by droplets of clouds and precipitation colliding with the aircraft. The local effect of that space charge depends on the flight regime (air speed, altitude, particle size, and cloud elevation). Such a dependence is displayed in the relation between the collector conductivity of the aircraft discharging circuit - on one hand, and the sum of all the residual conductivities contributing to aircraft discharge - on the other. Arguments are given in favor of variability in the aircraft electric capacitance. Techniques are suggested for measuring from factors to describe the aircraft charge.

  1. Measurements of Electrical and Thermal Conductivity of Iron Under Earth's Core Conditions

    NASA Astrophysics Data System (ADS)

    Ohta, K.; Kuwayama, Y.; Shimizu, K.; Yagi, T.; Hirose, K.; Ohishi, Y.

    2014-12-01

    Secular cooling of the Earth's core induces the convection of the conductive liquid outer core, which generates the geomagnetic field, and the growth of the solid inner core. Since iron is the primary component of the Earth's core, the electrical and thermal conductivity of iron in both solid and liquid states are key pieces of information for estimating the transport properties of the core. We performed electrical and thermal conductivity measurements on iron under core conditions in a laser-heated diamond anvil cell. Our electrical conductivity measurements on iron clearly show resistivity saturation phenomena in iron under high pressure and high temperature conditions as predicted in a recent laboratory-based model for the core conductivity (Gomi et al., 2013). Direct measurements of thermal diffusivity of iron have been also preformed at high pressures by using the pulsed light heating thermoreflectance technique, which enable us to confirm the validity of the Wiedemann-Franz law toward transition metal under high pressure.

  2. A cluster-glass magnetic state in R5Pd2 (R = Ho, Tb) compounds evidenced by AC-susceptibility and neutron scattering measurements

    NASA Astrophysics Data System (ADS)

    Gubkin, A. F.; Sherstobitova, E. A.; Terentyev, P. B.; Hoser, A.; Baranov, N. V.

    2013-06-01

    AC- and DC-susceptibility, high-field magnetization and neutron diffraction measurements have been performed in order to study the magnetic state of R5Pd2 (R = Ho, Tb) compounds. The results show that both compounds undergo cluster-glass freezing upon cooling below Tf. According to the neutron diffraction a long-range magnetic order is absent down to 2 K and magnetic clusters with short-range incommensurate antiferromagnetic correlations exist not only below Tf but also in a wide temperature range above the freezing temperature (at least up to 2Tf). A complex cluster-glass magnetic state existing in Ho5Pd2 and Tb5Pd2 down to low temperatures results in rather complicated magnetization behavior in DC and AC magnetic fields. Such an unusual magnetic state in compounds with a high rare-earth concentration may be associated with the layered type of their crystal structure and with substantial atomic disorder, which results in frustrations in the magnetic subsystem.

  3. A study of the impacts of flow direction and electrical constraints on vulnerability assessment of power grid using electrical betweenness measures

    NASA Astrophysics Data System (ADS)

    Wu, Di; Ma, Feng; Javadi, Milad; Thulasiraman, Krishnaiya; Bompard, Ettore; Jiang, John N.

    2017-01-01

    In this paper, we analyze the impacts of major electrical properties, including node constraints, line limits, and flow direction, on vulnerability assessment of power grid using several types of electrical betweenness measures. Specifically, we first propose a set of new electrical betweenness measures, which takes into account flow direction in power grids. Then, the impacts of major electrical properties on vulnerability assessment of power grid are analyzed by comparing the identification results of critical components based on the proposed electrical betweenness measures with those based on the other two types of electrical betweenness measures reported in the literature, which take into consideration node constraints and line limits, respectively. Analysis results show the important impact of flow direction on the identification of critical components. The results lead us to introduce a set of combined electrical betweenness measures that take into account node constraints, line limits, and flow direction together. Simulation results on the IEEE 300-bus system and the Italian power grid show that the combined electrical betweenness measures are superior in identifying critical components and more useful in assessing power grid vulnerability.

  4. Seasonal variations of atmospheric electricity measured at Amundsen-Scott South Pole Station

    NASA Astrophysics Data System (ADS)

    Reddell, B. D.; Benbrook, J. R.; Bering, E. A.; Cleary, E. N.; Few, A. A.

    2004-09-01

    Recent studies have shown that the general understanding of the Earth's global circuit is not entirely complete. Electric current originates from thunderstorm cloud tops and travels to the ionosphere, where it then leaks back down to the Earth's surface. Superimposed on this current is the dynamo generated from the interaction of the solar wind with Earth's magnetosphere. This paper investigates seasonal variations of the vertical electric field and current density as measured at the South Pole between 1991 and 1993. After initial data reduction, a model approach was used to decouple the magnetospheric and atmospheric components of the measurements. This approach calculated and subtracted the polar cap ionospheric potential from the measured data to obtain a signal of global tropospheric origin, in principle. The diurnal variations of the resulting data were averaged as a function of UT. These averages were calculated for the data as a whole and for the date sorted and binned by season and by magnetic activity level. The seasonally binned average results are consistent with recent papers indicating that the electric field measurement show global convective electrical activity to be a minimum during the Northern Hemisphere winter, in contradiction to the original 1929 Carnegie data. Because the electric field was a maximum during the Northern Hemisphere summer season, the midlatitude regions must contribute more strongly than the tropics to global atmospheric electricity. This analysis supports the link of electrical activity to global temperature. The magnetic activity binned results suggest that the polar cap potential model used underestimates the cross polar cap potential when there is a high Kp index.

  5. High electric field measurement with slab coupled optical sensors using nonlinear calibration

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    We describe the application of SCOS technology in non-intrusive, directional and spatially localized measurements of high electric fields. When measuring electric fields above a certain threshold, SCOS measurement sensitivity starts varying to a great extent and the linear approximation that assumes sensitivity to be constant breaks down. This means that a comprehensive nonlinear calibration method is required for accurate calibration of both low and high electric fields, while linear calibration can only be accurately applied for low fields. Nonlinear calibration method relies on the knowledge of the variability of sensitivity, while linear calibration relies on approximation of sensitivity with a constant value, which breaks down for high fields. We analyze and compare the two calibration methods by applying them to a same set of measurements. We measure electric field pulses with magnitudes from 1 MV/m to 8.2 MV/m, with sub-300 ns rise time and fall-off time constant of 60 μs. We show that the nonlinear calibration very accurately predicts all measured fields, both high and low, while the linear calibration becomes increasingly inaccurate for fields above 1 MV/m.

  6. Measurement of the electrical resistivity and Hall coefficient at high temperatures.

    PubMed

    Borup, Kasper A; Toberer, Eric S; Zoltan, Leslie D; Nakatsukasa, George; Errico, Michael; Fleurial, Jean-Pierre; Iversen, Bo B; Snyder, G Jeffrey

    2012-12-01

    The implementation of the van der Pauw (VDP) technique for combined high temperature measurement of the electrical resistivity and Hall coefficient is described. The VDP method is convenient for use since it accepts sample geometries compatible with other measurements. The technique is simple to use and can be used with samples showing a broad range of shapes and physical properties, from near insulators to metals. Three instruments utilizing the VDP method for measurement of heavily doped semiconductors, such as thermoelectrics, are discussed.

  7. Measurement of the electrical resistivity and Hall coefficient at high temperatures

    NASA Astrophysics Data System (ADS)

    Borup, Kasper A.; Toberer, Eric S.; Zoltan, Leslie D.; Nakatsukasa, George; Errico, Michael; Fleurial, Jean-Pierre; Iversen, Bo B.; Snyder, G. Jeffrey

    2012-12-01

    The implementation of the van der Pauw (VDP) technique for combined high temperature measurement of the electrical resistivity and Hall coefficient is described. The VDP method is convenient for use since it accepts sample geometries compatible with other measurements. The technique is simple to use and can be used with samples showing a broad range of shapes and physical properties, from near insulators to metals. Three instruments utilizing the VDP method for measurement of heavily doped semiconductors, such as thermoelectrics, are discussed.

  8. DC electric field effects during measurements of monopolar charge density and net space charge density near HVDC power lines

    SciTech Connect

    Misakian, M.; McKnight, R.H. )

    1989-10-01

    The influence of a dc electric field on the measurement of monopolar charge densities using an aspirator-type ion counter and the measurement of net space charge density using a Faraday cage or filter is examined. Optimum configurations which minimize the effect of the electric field are identified for each type of instrumentation. Key Words: Electric field, Faraday cage, filter, ion counter, measurement, measurement errors, monopolar charge density, net space charge.

  9. In situ electrical conductivity measurements of H2O under static pressure up to 28 GPa

    NASA Astrophysics Data System (ADS)

    Liu, Bao; Gao, Yang; Han, Yonghao; Ma, Yanzhang; Gao, Chunxiao

    2016-08-01

    The in situ electrical conductivity measurements on water in both solid state and liquid state were performed under pressure up to 28 GPa and temperature from 77 K to 300 K using a microcircuit fabricated on a diamond anvil cell (DAC). Water chemically ionization mainly contributes to electrical conduction in liquid state, which is in accord with the results obtained under dynamic pressure. Energy band theory of liquid water was used to understand effect of static pressure on electrical conduction of water. The electric conductivity of H2O decreased discontinuously by four orders of magnitude at 0.7-0.96 GPa, indicating water frozen at this P-T condition. Correspondingly, the conduction of H2O in solid state is determined by arrangement and bending of H-bond in ice VI and ice VII. Based on Jaccard theory, we have concluded that the charge carriers of ice are already existing ions and Bjerrum defects.

  10. Electrostatic sensors applied to the measurement of electric charge transfer in gas solids pipelines

    NASA Astrophysics Data System (ADS)

    Woodhead, S. R.; Denham, J. C.; Armour-Chelu, D. I.

    2005-01-01

    This paper describes the development of a number of electric charge sensors. The sensors have been developed specifically to investigate triboelectric charge transfer which takes place between particles and the pipeline wall, when powdered materials are conveyed through a pipeline using air. A number of industrial applications exist for such gas solids pipelines, including pneumatic conveyors, vacuum cleaners and dust extraction systems. The build-up of electric charge on pipelines and powdered materials can lead to electrostatic discharge and so is of interest from a safety viewpoint. The charging of powders can also adversely affect their mechanical handling characteristics and so is of interest to handling equipment engineers. The paper presents the design of the sensors, the design of the electric charge test rig and electric charge measurement test results.

  11. Intermittency analyses on the SIERRA measurements of the electric field fluctuations in the auroral zone

    NASA Astrophysics Data System (ADS)

    Tam, Sunny W. Y.; Chang, Tom; Kintner, Paul M.; Klatt, Eric

    2005-03-01

    We perform intermittency analyses on the electric field data obtained by the SIERRA sounding rocket in the auroral zone. The electric field fluctuations are broadband, covering the extremely low-frequency range with a power-law relation, similar to the type of fluctuations commonly observed at various altitudes of the auroral region. Our preliminary analyses of the data based on the technique of probability distribution functions indicate that the electric field fluctuations are intermittent in the spacecraft frame. Using the methods of wavelet analyses and local intermittency measures, we determine the degree of intermittency of the fluctuations at various scales. It is found that the electric field fluctuations are more intermittent at smaller scales.

  12. Correlated electric field and low-energy electron measurements in the low-altitude polar cusp

    NASA Technical Reports Server (NTRS)

    Kintner, P. M.; Ackerson, K. L.; Gurnett, D. A.; Frank, L. A.

    1978-01-01

    Correlated electric field and low-energy electron measurements are presented for two passes of Hawkeye 1 through the south polar cusp at 2000-km altitude during local morning. In one case the electric field reversal coincides with the boundary of detectable 5.2keV electron intensities and the equatorward boundary of the cusp. In the other case the electric field reversal and the 5.2 keV electron trapping boundary coincide, but the equatorward edge of the cusp as determined from the presence of 180 eV electron intensities is 5 degrees invariant latitude equatorward of the electric field reversal. It is concluded that in the second case, electron intensities associated with the polar cusp populate closed dayside field lines, and hence the corresponding equatorward edge of these electron intensities is not always an indicator of the boundary between closed dayside field lines and polar cap field lines.

  13. PNPI differential EDM spectrometer and latest results of measurements of the neutron electric dipole moment

    SciTech Connect

    Serebrov, A. P. Kolomenskiy, E. A.; Pirozhkov, A. N.; Krasnoshchekova, I. A.; Vasiliev, A. V.; Polyushkin, A. O.; Lasakov, M. S.; Murashkin, A. N.; Solovey, V. A.; Fomin, A. K.; Shoka, I. V.; Zherebtsov, O. M.; Alexandrov, E. B.; Dmitriev, S. P.; Dovator, N. A.; Geltenbort, P.; Ivanov, S. N.; Zimmer, O.

    2015-12-15

    In this work, the double chamber magnetic resonance spectrometer of the Petersburg Nuclear Physics Institute (PNPI) designed to measure the neutron electric dipole moment (EDM) is briefly described. A method for long storage of polarized ultracold neutrons in a resonance space with a superposed electric field collinear to the leading magnetic field is used. The results of the measurements carried out on the ILL reactor (Grenoble, France) are interpreted as the upper limit of the value of neutron EDM vertical bar d{sub n} vertical bar < 5.5 × 10{sup –26}e cm at the 90% confidence level.

  14. Contact-independent measurement of electrical conductance of a thin film with a nanoscale sensor.

    PubMed

    Mentzel, Tamar S; Maclean, Kenneth; Kastner, Marc A

    2011-10-12

    Contact effects are a common impediment to electrical measurements throughout the fields of nanoelectronics, organic electronics, and the emerging field of graphene electronics. We demonstrate a novel method of measuring electrical conductance in a thin film of amorphous germanium that is insensitive to contact effects. The measurement is based on the capacitive coupling of a nanoscale metal-oxide-semiconductor field-effect transistor (MOSFET) to the thin film so that the MOSFET senses charge diffusion in the film. We tune the contact resistance between the film and contact electrodes and show that our measurement is unaffected. With the MOSFET, we measure the temperature and field dependence of the conductance of the amorphous germanium, which are fit to a model of variable-range hopping. The device structure enables both a contact-independent and a conventional, contact-dependent measurement, which makes it possible to discern the effect of the contacts in the latter measurement. This measurement method can be used for reliable electrical characterization of new materials and to determine the effect of contacts on conventional electron transport measurements, thus guiding the choice of optimal contact materials.

  15. Laboratory measurements of electrical conductivities of hydrous and dry Mount Vesuvius melts under pressure

    NASA Astrophysics Data System (ADS)

    Pommier, A.; Gaillard, F.; Pichavant, M.; Scaillet, B.

    2008-05-01

    Quantitative interpretation of MT anomalies in volcanic regions requires laboratory measurements of electrical conductivities of natural magma compositions. The electrical conductivities of three lava compositions from Mount Vesuvius (Italy) have been measured using an impedance spectrometer. Experiments were conducted on both glasses and melts between 400 and 1300°C, at both ambient pressure in air and high pressures (up to 400 MPa). Both dry and hydrous (up to 5.6 wt % H2O) melt compositions were investigated. A change of the conduction mechanism corresponding to the glass transition was systematically observed. The conductivity data were fitted by sample-specific Arrhenius laws on either side of Tg. The electrical conductivity increases with temperature and is higher in the order tephrite, phonotephrite to phonolite. For the three investigated compositions, increasing pressure decreases the conductivity, although the effect of pressure is relatively small. The three investigated compositions have similar activation volumes (ΔV = 16-24 cm3 mol-1). Increasing the water content of the melt increases the conductivity. Comparison of activation energies (Ea) from conductivity and sodium diffusion and use of the Nernst-Einstein relation allow sodium to be identified as the main charge carrier in our melts and presumably also in the corresponding glasses. Our data and those of previous studies highlight the correlation between the Arrhenius parameters Ea and σ0. A semiempirical method allowing the determination of the electrical conductivity of natural magmatic liquids is proposed, in which the activation energy is modeled on the basis of the Anderson-Stuart model, σ0 being obtained from the compensation law and ΔV being fitted from our experimental data. The model enables the electrical conductivity to be calculated for the entire range of melt compositions at Mount Vesuvius and also satisfactorily predicts the electrical response of other melt compositions

  16. A Diagnostic for Electric Field Measurements in the Near/Far-Field Regions of ICRF Antenna

    NASA Astrophysics Data System (ADS)

    Martin, E. H.; Caughman, J. B. O.; Isler, R. C.

    2015-11-01

    The physics mechanisms of wave heating and current drive processes in the bulk hot plasma are generally well identified. However, details of the wave-plasma interaction with a material surface in the cold plasma edge are still not fully understood. The driver behind this interaction is the time-periodic wave electric field and is referred to as the near/far-field depending on the location with respect to the antenna. Various models have been formulated to capture the near/far-field physics but have not been tested experimentally. Thus, a diagnostic capable of measuring the electric field with temporal and 3D-spatial resolution is critical for confidence in the codes used to design next generation ICRF antennas. This research is focused on the development of a laser based spectroscopic technique, Doppler-free saturation spectroscopy (DFSS), and its implementation to study near/far-field physics. Using DFSS the spectra line profile of various electronic transitions are measured and fit to a quantum mechanical model incorporating both magnetic and dynamic electric field operators. The electric field direction and magnitude are extracted from the fit. The experimental setup and planned experiments will be discussed. Additionally, initial measurements of fitted Hδ spectrum under the influence of known electric and magnetic fields will be presented.

  17. Liquid crystal infiltrated photonic crystal fibers for electric field intensity measurements.

    PubMed

    Mathews, Sunish; Farrell, Gerald; Semenova, Yuliya

    2011-06-10

    The application of nematic liquid crystal infiltrated photonic crystal fiber as a sensor for electric field intensity measurement is demonstrated. The device is based on an intrinsic sensing mechanism for electric fields. The sensor probe, which consists of a 1  cm infiltrated section of photonic crystal fiber with a lateral size of ∼125  μm, is very compact with small size and weight. A simple all-fiber design for the sensor is employed in an intensity based measurement scheme. The transmitted and reflected power of the infiltrated photonic crystal fiber is shown to have a linear response with the applied electric field. The sensor is operated in the telecommunication window at 1550  nm. The temperature dependence of the device at this operating wavelength is also experimentally studied and discussed. These structures can be used to accurately measure electric field intensity and can be used for the fabrication of all-fiber sensors for high electric field environments as both an in-line and reflective type point sensor.

  18. Laboratory measurements of basalts electrical resistivity under deep oceanic crustal conditions

    NASA Astrophysics Data System (ADS)

    Violay, M. E.; Gibert, B.; Azais, P.; Pezard, P. A.; Flovenz, O. G.; Asmundsson, R.

    2009-12-01

    For sixty years, electrical resistivity soundings have been used to explore geothermal resources in Iceland. They have generally revealed two zones of high electrical conductivity, one at shallow depths (Flovenz et al., 1985) and another at 10-30 km depth (Beblo and Björnsson, 1978). The interpretation of these conductive zones in terms of composition and in-situ physical conditions is often ambiguous, as various parameters can explain these observations like temperature, partial melting, change in minerals and type of pore fluid. Accurate interpretations of resistivity data needed for geothermal exploration require laboratory measurements of electrical conductivities performed on rock samples at different conditions. We present here a method to measure electrical conductivity of rocks under deep crustal conditions for oceanic crustal rock, i.e. at temperatures up to 600°C, confining pressures up to 200 MPa and pore fluid pressures up to 50 MPa. The method has been developed in a internally heated, gas pressure apparatus (Paterson press). Electrical conductivity is measured on large cylindrical samples (15 to 22 mm in diameter and 10 to 15 mm in length) in a two parallel electrodes geometry. Such experiments require that the fluid saturated sample is sleeved in an impermeable and deformable jacket serving to separate the confining pressure medium (high pressure argon) from the pore fluid saturated sample. At temperature above 200°C a metal sleeve must be used, although it induces high leakage currents that could affect electrical measurements. The leakage currents are reduced using addition of 2 guard-ring parallel electrodes (Glover, 1995). The electrical impedance of basalt has been measured over a frequency range from 10 -1 to 106 Hertz. Five different types of low porosity basalts were selected to cover a range in alteration grade, from albitic to granulite facies. Application of this method will provide data on electrical conductivity of fresh and altered

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

    NASA Astrophysics Data System (ADS)

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

    2015-08-01

    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 21S→11 1P transition through collision induced fluorescence from 43D→23P. 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) = ρ0(r/r0)3, where ρ(r) is the local space charge density, ρ0 = 6 × 10-3 Coulomb/m3, r is the local radial value, and r0 is the radius of the electrode.

  20. 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.

  1. A Step Towards Electric Propulsion Testing Standards: Pressure Measurements and Effective Pumping Speeds

    NASA Technical Reports Server (NTRS)

    Dankanich, John W.; Swiatek, Michael W.; Yim, John T.

    2012-01-01

    The electric propulsion community has been implored to establish and implement a set of universally applicable test standards during the research, development, and qualification of electric propulsion systems. Existing practices are fallible and result in testing variations which leads to suspicious results, large margins in application, or aversion to mission infusion. Performance measurements and life testing under appropriate conditions can be costly and lengthy. Measurement practices must be consistent, accurate, and repeatable. Additionally, the measurements must be universally transportable across facilities throughout the development, qualification, spacecraft integration and on-orbit performance. A preliminary step to progress towards universally applicable testing standards is outlined for facility pressure measurements and effective pumping speed calculations. The standard has been applied to multiple facilities at the NASA Glenn Research Center. Test results and analyses of universality of measurements are presented herein.

  2. Noncontact technique for measuring the electrical resistivity and magnetic susceptibility of electrostatically levitated melts

    NASA Astrophysics Data System (ADS)

    Rustan, G. E.; Spyrison, N. S.; Kreyssig, A.; Prozorov, R.; Goldman, A. I.

    2012-02-01

    Over the last two decades the popularity of levitation methods for studying equilibrium and supercooled melts has increased steadily. Measurements of density, viscosity, surface tension, and atomic structure have become well established. In contrast, measurements of electrical resistivity and magnetic susceptibility of levitated melts have been very limited. To fill this void, we have combined the tunnel diode oscillator (TDO) technique with electrostatic levitation (ESL) to perform inductively coupled measurements on levitated melts. A description of the basic operating principles of the TDO and ESL will be given, as well as a description of the implementation and performance characteristics of this technique. Preliminary measurements of electrical resistivity in the solid and liquid state will be presented for samples of Zr, Si, and Ge, as well as the measurements of ferromagnetic transitions in Fe and Co based alloys.

  3. LH and ICRH RF electric field measurements using Doppler-free Saturation Spectroscopy

    NASA Astrophysics Data System (ADS)

    Martin, E. H.; Zafar, A.; Caughman, J. B. O.; Isler, R. C.; Bell, G. L.

    2016-10-01

    The physics mechanisms of wave heating and current drive processes in the bulk hot plasma are generally well identified, however, details of the wave-plasma interaction in the cold plasma edge are still not fully understood. To investigate the alluding physics non-perturbative diagnostics are required due to the large energy flux traversing the space associated with the corresponding RF antenna/launcher. A spectroscopic diagnostic, based on Doppler-free saturation spectroscopy, is currently under development at ORNL that will be capable of measuring RF electric fields with high precision (20 V/cm). The RF electric field is determined by systematically fitting a Balmer series spectral line profile obtained via DFSS using a previous validated non-perturbative quantum mechanically model. The spectral line profile is measured using Doppler-free saturation spectroscopy (DFSS). DFSS is a laser-based technique involving two counter-propagating beams, referred to as the pump and probe, which are made to overlap at a single point in space. The frequency of the laser is swept over that associated with the electronic transition of interest and the probe beam absorption intensity is measured. In this presentation an active spectroscopic technique allowing for measurements of the RF electric field driving wave-plasma interactions for lower hybrid (LH) and ion cyclotron resonance heating (ICRH) systems, based on DFSS, will be discussed. Initial measurements of the electric field in the magnetized capacitively coupled RF sheath obtained on a laboratory test stand will be presented.

  4. Electrokinetic characterization of porous plugs from streaming potential coupled with electrical resistance measurements.

    PubMed

    Szymczyk, A; Fievet, P; Foissy, A

    2002-11-15

    The zeta potential of mixed nickel-iron oxide particles is evaluated by a new laboratory instrument. This latter allows the measurement of streaming potential together with the electrical resistance of porous plugs. The conductivity of electrolyte inside plug (pore conductivity) is deduced from electrical resistance measurements and is used together with streaming potential to evaluate the zeta potential by accounting for the surface conduction phenomenon. It is shown that neglecting the surface conduction phenomenon leads to a substantial underestimation of the zeta potential. The coupled measurements of streaming potential and plug electrical resistance yield zeta potential values that are in very good agreement with those obtained by electrophoresis. The densification of the porous plug with increasing pressure increments is put in evidence by the decrease in measured streaming potentials. Electrical resistance measurements make it possible to account for the increase in surface conductivity resulting from the more compacted structure of the plug. By doing so, the calculated zeta potential is found to be virtually independent of the pressure difference involved in streaming potential experiments, whereas the negligence of surface conduction phenomenon leads to a decrease in the apparent zeta potential with increasing pressure level.

  5. A quadruple-scanning-probe force microscope for electrical property measurements of microscopic materials.

    PubMed

    Higuchi, Seiji; Kubo, Osamu; Kuramochi, Hiromi; Aono, Masakazu; Nakayama, Tomonobu

    2011-07-15

    Four-terminal electrical measurement is realized on a microscopic structure in air, without a lithographic process, using a home-built quadruple-scanning-probe force microscope (QSPFM). The QSPFM has four probes whose positions are individually controlled by obtaining images of a sample in the manner of atomic force microscopy (AFM), and uses the probes as contacting electrodes for electrical measurements. A specially arranged tuning fork probe (TFP) is used as a self-detection force sensor to operate each probe in a frequency modulation AFM mode, resulting in simultaneous imaging of the same microscopic feature on an insulator using the four TFPs. Four-terminal electrical measurement is then demonstrated in air by placing each probe electrode in contact with a graphene flake exfoliated on a silicon dioxide film, and the sheet resistance of the flake is measured by the van der Pauw method. The present work shows that the QSPFM has the potential to measure the intrinsic electrical properties of a wide range of microscopic materials in situ without electrode fabrication.

  6. A quadruple-scanning-probe force microscope for electrical property measurements of microscopic materials

    NASA Astrophysics Data System (ADS)

    Higuchi, Seiji; Kubo, Osamu; Kuramochi, Hiromi; Aono, Masakazu; Nakayama, Tomonobu

    2011-07-01

    Four-terminal electrical measurement is realized on a microscopic structure in air, without a lithographic process, using a home-built quadruple-scanning-probe force microscope (QSPFM). The QSPFM has four probes whose positions are individually controlled by obtaining images of a sample in the manner of atomic force microscopy (AFM), and uses the probes as contacting electrodes for electrical measurements. A specially arranged tuning fork probe (TFP) is used as a self-detection force sensor to operate each probe in a frequency modulation AFM mode, resulting in simultaneous imaging of the same microscopic feature on an insulator using the four TFPs. Four-terminal electrical measurement is then demonstrated in air by placing each probe electrode in contact with a graphene flake exfoliated on a silicon dioxide film, and the sheet resistance of the flake is measured by the van der Pauw method. The present work shows that the QSPFM has the potential to measure the intrinsic electrical properties of a wide range of microscopic materials in situ without electrode fabrication.

  7. Monitoring of vulcanization process using measurement of electrical properties during linear increasing temperature

    NASA Astrophysics Data System (ADS)

    Seliga, E.; Bošák, O.; Koštial, P.; Dvořák, Z.; Kubliha, M.; Minárik, S.; Labaš, V.

    2015-04-01

    The article presents the possibilities of diagnostics of irreversible chemical reaction - vulcanization in case of laboratory prepared rubber mixture based on styrene - butadiene (SBR) using measurements of selected physical parameters. Our work is focused on the measurement of current rheologic parameters (torque at defined shear deformation) and selected electrical parameters (DC conductivity) during linear increasing temperature. The individual steps of vulcanization are well identified by means of measurements of rheologic parameters, while significantly affecting the value of the electrical conductivity. The value of the electrical conductivity increases with the increasing of rate of the crossbridging reactions during vulcanization. The rate of the heating affects both types of measurements. When the rate of the heating is increasing the temperature of the beginning of networking step of reactions and also the rate of vulcanization grow. The sensitivity of the both types of measurements allows a good mathematical description of the temperature dependence of the torque and the electric conductivity during the vulcanization of rubber mixtures based on SBR.

  8. A Multi-Level Grid Interactive Bi-directional AC/DC-DC/AC Converter and a Hybrid Battery/Ultra-capacitor Energy Storage System with Integrated Magnetics for Plug-in Hybrid Electric Vehicles

    SciTech Connect

    Onar, Omer C

    2011-01-01

    This study presents a bi-directional multi-level power electronic interface for the grid interactions of plug-in hybrid electric vehicles (PHEVs) as well as a novel bi-directional power electronic converter for the combined operation of battery/ultracapacitor hybrid energy storage systems (ESS). The grid interface converter enables beneficial vehicle-to-grid (V2G) interactions in a high power quality and grid friendly manner; i.e, the grid interface converter ensures that all power delivered to/from grid has unity power factor and almost zero current harmonics. The power electronic converter that provides the combined operation of battery/ultra-capacitor system reduces the size and cost of the conventional ESS hybridization topologies while reducing the stress on the battery, prolonging the battery lifetime, and increasing the overall vehicle performance and efficiency. The combination of hybrid ESS is provided through an integrated magnetic structure that reduces the size and cost of the inductors of the ESS converters. Simulation and experimental results are included as prove of the concept presenting the different operation modes of the proposed converters.

  9. Use of low-frequency electrical impedance measurements to determine phospholipid content in amniotic fluid

    NASA Astrophysics Data System (ADS)

    DeLuca, F.; Cametti, C.; Zimatore, G.; Maraviglia, B.; Pachi', A.

    1996-09-01

    In this report we propose a new method for an in vitro test of the foetal lung maturity based on the measurement of the electrical conductivity of the overall amniotic fluid obtained from transabdominal amniocentesis, since this quantity can be linked to a first approximation in a very simple way to the phospholipid content. We have carried out measurements of 85 different samples of amniotic fluid as a function of gestation weeks and we have observed a pronounced change of the electrical conductivity that reflects the increase in the phospholipid concentration occurring at the end of normal pregnancies. The method could be further developed to obtain similar information on in vivo experiments by means of bioelectric impedance tomography, taking advantage of the frequency dependence of the tissue electrical impedance.

  10. Observation of thunderstorms by multilevel electric field measurement system and radar

    NASA Astrophysics Data System (ADS)

    Soula, S.; Sauvageot, H.; Saissac, M. P.; Chauzy, S.

    1995-03-01

    During the summer of 1992, an experiment was conducted in southwestern France, close to the Pyrenees, at the Centre de Recherches Atmospheriques (CRA) in order to study the evolution of the electric field measured at several levels below thunderclouds. We used a field mill flush to the ground and four field sensors, suspended from an insulated cable and distributed between 0 and 48 m. These altitude sensors separately measure the ambient electric field and the field created by the sensor itself. The Rabelais millimetric radar provides reflectivities and Doppler velocities of cloud and rain systems. Meteorological data like wind velocity, humidity, temperature, and rainfall rate are recorded at the site. Two storm intervals are studied, one on July 30 and one on August 6. Both examples give an idea on how the electric field signature during the development or advection of a convective cloud can be different at the ground and at altitudes of a few tens of meters.

  11. The time resolved measurement of ultrashort terahertz-band electric fields without an ultrashort probe

    SciTech Connect

    Walsh, D. A. Snedden, E. W.; Jamison, S. P.

    2015-05-04

    The time-resolved detection of ultrashort pulsed THz-band electric field temporal profiles without an ultrashort laser probe is demonstrated. A non-linear interaction between a narrow-bandwidth optical probe and the THz pulse transposes the THz spectral intensity and phase information to the optical region, thereby generating an optical pulse whose temporal electric field envelope replicates the temporal profile of the real THz electric field. This optical envelope is characterised via an autocorrelation based FROG (frequency resolved optical gating) measurement, hence revealing the THz temporal profile. The combination of a narrow-bandwidth, long duration, optical probe, and self-referenced FROG makes the technique inherently immune to timing jitter between the optical probe and THz pulse and may find particular application where the THz field is not initially generated via ultrashort laser methods, such as the measurement of longitudinal electron bunch profiles in particle accelerators.

  12. Application of electrical methods to measure microbial activity in soils: Preliminary microcosm results

    SciTech Connect

    Cox, B.L. Sweet, A.; Majer, E.

    1997-12-01

    The application of the geophysical technique known as self-potential to the measurement of microbial activity was tested on laboratory microcosms containing ferric iron and iron-reducing bacteria Shewanella alga BrY. Measurements of the electrical response of silver-coated copper electrodes distributed along a Teflon probe inserted into sterile and inoculated layers containing either ferric chloride, ferric citrate, or ferric oxide rich soil were recorded over hours or days. Strong electrical signals reached values more negative than {minus}400 mV for all types of inoculated ferric iron layers. Electric signals in sterile control layers, by contrast, rarely reached values more negative than {minus}150 mV. These preliminary experiments indicate that it may be possible to apply the self-potential geophysical method to monitor bioremediation in the field.

  13. The time resolved measurement of ultrashort terahertz-band electric fields without an ultrashort probe

    NASA Astrophysics Data System (ADS)

    Walsh, D. A.; Snedden, E. W.; Jamison, S. P.

    2015-05-01

    The time-resolved detection of ultrashort pulsed THz-band electric field temporal profiles without an ultrashort laser probe is demonstrated. A non-linear interaction between a narrow-bandwidth optical probe and the THz pulse transposes the THz spectral intensity and phase information to the optical region, thereby generating an optical pulse whose temporal electric field envelope replicates the temporal profile of the real THz electric field. This optical envelope is characterised via an autocorrelation based FROG (frequency resolved optical gating) measurement, hence revealing the THz temporal profile. The combination of a narrow-bandwidth, long duration, optical probe, and self-referenced FROG makes the technique inherently immune to timing jitter between the optical probe and THz pulse and may find particular application where the THz field is not initially generated via ultrashort laser methods, such as the measurement of longitudinal electron bunch profiles in particle accelerators.

  14. Direct electrical transport measurement on a single thermoelectric nanowire embedded in an alumina template.

    PubMed

    Ben Khedim, Meriam; Cagnon, Laurent; Garagnon, Christophe; Serradeil, Valerie; Bourgault, Daniel

    2016-04-28

    Electrical conductivity is a key parameter to increase the performance of thermoelectric materials. However, the measurement of such performance remains complex for 1D structures, involving tedious processing. In this study, we present a non-destructive, rapid and easy approach for the characterization of electrical conductivity of Bi2Te3 based single nanowires. By controlling the nanowire overgrowth, each nanowire emerges in the form of a micrometric hemisphere constituting a unique contact zone for direct nanoprobing. As nanowires need no preliminary preparation and remain in their template during measurement, we avoid oxidation effects and time-consuming processing. Electrical transport results show a low nanowire resistivity for compact nanowires obtained at low overpotential. Such values are comparable to bulk materials and thin films. This method not only confirmed its reliability, but it could also be adopted for other semiconducting or metallic electrodeposited nanowires.

  15. Vortex dynamics and irreversibility line in optimally doped SmFeAsO0.8F0.2 from ac susceptibility and magnetization measurements

    NASA Astrophysics Data System (ADS)

    Prando, G.; Carretta, P.; de Renzi, R.; Sanna, S.; Palenzona, A.; Putti, M.; Tropeano, M.

    2011-05-01

    Ac susceptibility and static magnetization measurements were performed in the optimally doped SmFeAsO0.8F0.2 superconductor. The field-temperature phase diagram of the superconducting state was drawn, and, in particular, the features of the flux lines were derived. The dependence of the intragrain depinning energy on the magnetic field intensity was derived in the thermally activated flux-creep framework, enlightening a typical 1/H dependence in the high-field regime. The intragrain critical current density was extrapolated in the zero-temperature and zero-magnetic-field limit, showing a remarkably high value Jc0(0)~2×107 A/cm2, which demonstrates that this material is rather interesting for potential future technological applications.

  16. AC magnetic measurement of LiFeAs at pressures up to 5.2 GPa: The relation between T c and the structural parameters

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Shuhei; Yamaguchi, Nobuhiro; Mito, Masaki; Deguchi, Hiroyuki; Baker, Peter. J.; Blundell, Stephen. J.; Pitcher, Michael. J.; Parker, Dinah. R.; Clarke, Simon. J.

    2013-08-01

    The pressure effects on the 111-type Fe-based superconductor LiFeAs were investigated through AC susceptibility measurements and X-ray diffraction experiments, and revealed a correlation between the superconducting transition temperature ( T c ) and the As-Fe-As bond angle ( α) rather than the height of As from the Fe layers ( h As). As the pressure was increased, T c of 17 K at P = 0 GPa decreased down to 10 K at P = 5.2 GPa. According to a previous report from an X-ray diffraction experiment, α changes from 101.5° at 0 GPa to 97.8° at 17 GPa. The obtained change in T c is consistent with Lee et al.'s plot of T c as a function of α, and from this result, we conclude that T c will fall to zero at around α = 98°.

  17. Electrical properties of AC{sub 3}B{sub 4}O{sub 12}-type perovskite ceramics with different cation vacancies

    SciTech Connect

    Li, Guizhong; Chen, Zhi; Sun, Xiaojun; Liu, Laijun; Fang, Liang; Elouadi, Brahim

    2015-05-15

    Highlights: • AC{sub 3}B{sub 4}O{sub 12} perovskite with different concentration cation vacancies were prepared. • Cell parameter decreases with the increase of concentration of cation vacancies. • PTCO and CTO remain high dielectric permittivity but depress loss greatly. • Dielectric loss associates with cation vacancies and motion of oxygen vacancies. - Abstract: AC{sub 3}B{sub 4}O{sub 12}-type perovskite CaCu{sub 3}Ti{sub 4}O{sub 12} (CCTO), □{sub 0.34}Pr{sub 0.67}Cu{sub 3}Ti{sub 4}O{sub 12} (PCTO), □{sub 1}Cu{sub 3}Ta{sub 2}Ti{sub 2}O{sub 12} (CTTO), □{sub 2}Cu{sub 2}Ta{sub 4}O{sub 12} (CTO) ceramics with different concentration cation vacancies were prepared through traditional solid state reaction method. X-ray diffraction analysis indicated that CCTO and PCTO are perovskite cubic with space group Im-3 (no. 204) while CTTO and CTO are Pm-3 (no. 200). Cell parameter of the samples dramatically increases with the increase of cation vacancies. Dielectric permittivity of them maintains very high value of ∼10{sup 4} from room temperature to 550 K but the dielectric loss is depressed with the increase of cation vacancies in the same space group. The dielectric properties and conductivity behavior were described by the Debye relaxation and the universal dielectric response, respectively. The effect mechanism of cation vacancy and crystal structure on carrier transposition were discussed.

  18. Seasonal Variations of Atmospheric Electricity Measured at Amundsen-Scott South Pole Station

    NASA Astrophysics Data System (ADS)

    Reddell, B. D.; Benbrook, J. R.; Bering, E. A.; Cleary, E. N.; Few, A. A.

    2004-12-01

    This paper investigates seasonal variations of the vertical electric field and current density as measured at the South Pole between 1991 and 1993. After initial data reduction, a model approach was used to decouple the magnetospheric and atmospheric components of the measurements. This approach calculated and subtracted the polar-cap ionospheric potential from the measured data to obtain a signal of global tropospheric origin, in principle. The diurnal variations of the resulting data were averaged as a function of UT. These averages were calculated for the data as a whole and for the date sorted and binned by season and by magnetic activity level. The seasonally-binned average results are consistent with recent papers indicating that the electric field measurement show global convective-electrical activity to be a minimum during the northern hemisphere winter, in contradiction to the original 1929 Carnegie data. Because the electric field was a maximum during the northern hemisphere summer season, the mid-latitude regions must contribute more strongly than the tropics to global atmospheric electricity. This analysis supports the link of electrical activity to global temperature. The magnetic activity binned results suggest that the polar cap potential model used under estimates the cross polar cap potential when there is a high Kp index. This result can be explained if the model did not have equal weighting across the Kp range or if the limitation on the spherical harmonic coefficients did not give the potential at the South Pole. A complete high-latitude model is needed in order to estimate saturation of the cross-cap potential, as some theories predict.

  19. Electric fields and neutral winds from monostatic incoherent scatter measurements by means of stochastic inversion

    NASA Astrophysics Data System (ADS)

    Nygrén, T.; Aikio, A. T.; Kuula, R.; Voiculescu, M.

    2011-05-01

    A new method utilizing stochastic inversion in determining the electric field and neutral wind from monostatic beam swing incoherent scatter measurements is described. The method consists of two stages. In the first stage, beam-aligned ion velocities from a chosen F region height interval and a set of subsequent beam directions are taken as measurements. The unknowns are the two electric field components and the field-aligned ion velocity profile. The solution gives the most probable values of the unknowns with error estimates. In the second stage, the measurements consist of beam-aligned ion velocities from the E region, and the electric fields given by the first inversion problem are also used as measurements. The number of applied beam directions may be greater than in the first inversion problem. This is a feasible approach since the neutral wind usually changes more slowly than the electric field. The solution of the second inversion problem gives the most probable values of the three neutral wind components. Results of the method are shown for 11 September 2005, when the European Incoherent Scatter (EISCAT) UHF radar was running in the CP2 experiment mode, which is a four-position 6 min monostatic cycle. In addition, from each beam direction a tristatic measurement at one F region range gate was made using two additional receivers. That allowed comparison between the monostatic and tristatic electric field results, which were in excellent agreement. The calculated neutral wind components were in good accordance with previous measurements during disturbed conditions from the same site.

  20. Imaging of Vector Electric Fields Surrounding Auroral Arcs from Multibeam Incoherent Scatter Radar Measurements.

    NASA Astrophysics Data System (ADS)

    Maksimova, N.; Varney, R. H.; Cosgrove, R. B.; Kaeppler, S. R.; Nicolls, M. J.

    2015-12-01

    Evaluating the ionospheric electric fields and current systems surrounding auroral arcs aids in distinguishing physical mechanisms that drive arc generation and current closure. Auroral forms involve spatial scales that are small in comparison with the magnetosphere-ionosphere-thermosphere (MIT) system, and yet these forms are thought to be closely tied to the overall system response. Spatially resolved measurements of the horizontal ionospheric current can, in principle, be used to determine the field-aligned currents (FAC) that are responsible for energy transfer between the magnetosphere and the ionosphere/thermosphere, leading to heating and upwelling of the neutral gas and acceleration of ion upflows and outflows. Furthermore, the closure of FACs in the ionosphere regulates modes of magnetospheric convection and substorms. An algorithm has been developed to image the local structure in the convection electric field using multibeam incoherent scatter radar (ISR) measurements. Given the inherent difficulty of reconstructing vector quantities from line of sight (LOS) velocity measurements, the algorithm's aim is to select from the solution space for the possible field configurations a unique solution for the electric field distribution by constraining the reconstructed electric field to reproduce the LOS measurements within measurement errors while simultaneously minimizing a measure of the field's curvature and absolute gradient. Using the method of Lagrange multipliers, the algorithm regularizes the underdetermined problem defined by the LOS radar velocity measurements and guarantees a unique solution when the average measurement error is smaller than the average measurement amplitude. The algorithm is tested on a variety of simulated fields in a sensitivity study to determine the extent to which the solution depends on the a priori assumptions and the observation geometry. In addition, a case study of a quiescent auroral arc observed by the Poker Flat