Sample records for vector dc electric
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Method and system for operating an electric motor
Gallegos-Lopez, Gabriel; Hiti, Silva; Perisic, Milun
2013-01-22
Methods and systems for operating an electric motor having a plurality of windings with an inverter having a plurality of switches coupled to a voltage source are provided. A first plurality of switching vectors is applied to the plurality of switches. The first plurality of switching vectors includes a first ratio of first magnitude switching vectors to second magnitude switching vectors. A direct current (DC) current associated with the voltage source is monitored during the applying of the first plurality of switching vectors to the plurality of switches. A second ratio of the first magnitude switching vectors to the second magnitude switching vectors is selected based on the monitoring of the DC current associated with the voltage source. A second plurality of switching vectors is applied to the plurality of switches. The second plurality of switching vectors includes the second ratio of the first magnitude switching vectors to the second magnitude switching vectors.
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Initial Results from the Vector Electric Field Investigation on the C/NOFS Satellite
NASA Technical Reports Server (NTRS)
Pfaff, R.; Rowland, D.; Acuna, M.; Le, G.; Farrell, W.; Holzworth, R.; Wilson, G.; Burke, W.; Freudenreich, H.; Bromund, K.;
2009-01-01
Initial results are presented from the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. The VEFI instrument includes a vector DC electric field detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux gate magnetometer, an optical lightning detector, and associated electronics including a burst memory. The DC electric field detector has revealed zonal and meridional electric fields that undergo a diurnal variation, typically displaying eastward and outward-directed fields during the day and westward and downward-directed fields at night. In general, the measured DC electric field amplitudes are in the 0.5-2 mV/m range, corresponding to I3 x B drifts of the order of 30-150 m/s. What is surprising is the high degree of large-scale (10's to 100's of km) structure in the DC electric field, particularly at night, regardless of whether well-defined spread-F plasma density depletions are present. The spread-F density depletions and corresponding electric fields that have been detected thus far have displayed a preponderance to appear between midnight and dawn. Associated with the narrow plasma depletions that are detected are broad spectra of electric field and plasma density irregularities for which a full vector set of measurements is available for detailed study. On some occasions, localized regions of low frequency (< 8 Hz) magnetic field broadband irregularities have been detected, suggestive of filamentary currents, although there is no one-to-one correspondence of these waves with the observed plasma density depletions, at least within the data examined thus far. Finally, the data set includes a wide range of ELF/VLF/HF waves corresponding to a variety of plasma waves, in particular banded ELF hiss, whistlers, and lower hybrid wave turbulence triggered by lightning-induced sferics. The VEFI data set represents a treasure trove of measurements that are germane to numerous fundamental aspects of the electrodynamics and irregularities inherent to the Earth's low latitude ionosphere.
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DC Electric Fields, Associated Plasma Drifts, and Irregularities Observed on the C/NOFS Satellite
NASA Technical Reports Server (NTRS)
Pfaff, R.; Freudenreich, H.; Klenzing, J.
2011-01-01
Results are presented from the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. The VEFI instrument includes a vector DC electric field detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux gate magnetometer, an optical lightning detector, and associated electronics including a burst memory. Compared to data obtained during more active solar conditions, the ambient DC electric fields and their associated E x B drifts are variable and somewhat weak, typically < 1 mV/m. Although average drift directions show similarities to those previously reported, eastward/outward during day and westward/downward at night, this pattern varies significantly with longitude and is not always present. Daytime vertical drifts near the magnetic equator are largest after sunrise, with smaller average velocities after noon. Little or no pre-reversal enhancement in the vertical drift near sunset is observed, attributable to the solar minimum conditions creating a much reduced neutral dynamo at the satellite altitude. The nighttime ionosphere is characterized by larger amplitude, structured electric fields, even where the plasma density appears nearly quiescent. Data from successive orbits reveal that the vertical drifts and plasma density are both clearly organized with longitude. The spread-F density depletions and corresponding electric fields that have been detected thus far have displayed a preponderance to appear between midnight and dawn. Associated with the narrow plasma depletions that are detected are broad spectra of electric field and plasma density irregularities for which a full vector set of measurements is available for detailed study. The VEFI data represents a new set of measurements that are germane to numerous fundamental aspects of the electrodynamics and irregularities inherent to the Earth s low latitude ionosphere.
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NASA Technical Reports Server (NTRS)
Pfaff, R.; Rowland, D.; Klenzing, J.; Freudenreich, H.; Bromund, K.; Liebrecht, C.; Roddy, P.; Hunton, D.
2009-01-01
DC electric field observations and associated plasma drifts gathered with the Vector Electric Field Investigation on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite typically reveal considerable variation at large scales (approximately 100's of km), in both daytime and nighttime cases, with enhanced structures usually confined to the nightside. Although such electric field structures are typically associated with plasma density depletions and structures, as observed by the Planar Langmuir Probe on C/NOFS, what is surprising is the number of cases in which large amplitude, structured DC electric fields are observed without a significant plasma density counterpart structure, including their appearance at times when the ambient plasma density appears relatively quiescent. We investigate the relationship of such structured DC electric fields and the ambient plasma density in the C/NOFS satellite measurements observed thus far, taking into account both plasma density depletions and enhancements. We investigate the mapping of the electric fields along magnetic field lines from distant altitudes and latitudes to locations where the density structures, which presumably formed the original seat of the electric fields, are no longer discernible in the observations. In some cases, the electric field structures and spectral characteristics appear to mimic those associated with equatorial spread-F processes, providing important clues to their origins. We examine altitude, seasonal, and longitudinal effects in an effort to establish the origin of such structured DC electric fields observed both with, and without, associated plasma density gradients
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NASA Astrophysics Data System (ADS)
Kevorkyants, S. S.
2018-03-01
For theoretically studying the intensity of the influence exerted by the polarization of the rocks on the results of direct current (DC) well logging, a solution is suggested for the direct inner problem of the DC electric logging in the polarizable model of plane-layered medium containing a heterogeneity by the example of the three-layer model of the hosting medium. Initially, the solution is presented in the form of a traditional vector volume-integral equation of the second kind (IE2) for the electric current density vector. The vector IE2 is solved by the modified iteration-dissipation method. By the transformations, the initial IE2 is reduced to the equation with the contraction integral operator for an axisymmetric model of electrical well-logging of the three-layer polarizable medium intersected by an infinitely long circular cylinder. The latter simulates the borehole with a zone of penetration where the sought vector consists of the radial J r and J z axial (relative to the cylinder's axis) components. The decomposition of the obtained vector IE2 into scalar components and the discretization in the coordinates r and z lead to a heterogeneous system of linear algebraic equations with a block matrix of the coefficients representing 2x2 matrices whose elements are the triple integrals of the mixed derivatives of the second-order Green's function with respect to the parameters r, z, r', and z'. With the use of the analytical transformations and standard integrals, the integrals over the areas of the partition cells and azimuthal coordinate are reduced to single integrals (with respect to the variable t = cos ϕ on the interval [-1, 1]) calculated by the Gauss method for numerical integration. For estimating the effective coefficient of polarization of the complex medium, it is suggested to use the Siegel-Komarov formula.
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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 wind is investigated. Then we will show the irradiated region during the sounding rocket flight, and examine a possibility that a polarization electric field is generated in this region.
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The Vector Electric Field Investigation on the C/NOFS Satellite
NASA Technical Reports Server (NTRS)
Pfaff, R.; Acuna, M.; Kujawski, J.; Fourre, R.; Uribe, P.; Hunsaker, F.; Rowland, D.; Le, G.; Farrell, W.; Maynard, N.;
2008-01-01
We provide an overview of the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. VEFI is a NASA/GSFC instrument funded by the Air Force Research Laboratory whose main objectives are to: 1) investigate the role of the ambient electric fields in initiating nighttime ionospheric density depletions and turbulence; 2) determine the quasi-DC electric fields associated with abrupt, large amplitude, density depletions, and 3) quantify the spectrum of the wave electric fields and plasma densities (irregularities) associated with density depletions typically referred to as equatorial spread-F. The VEFI instrument includes a vector electric field double probe detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux-gate magnetometer, an optical lightning detector, and associated electronics. The heart of the instrument is the set of detectors designed to measure DC and AC electric fields using 6 identical booms that provide 3 axis, 20-m tip-to-tip orthogonal double probes. Each probe extends a 10 cm diameter sphere containing an embedded preamplifier. VEFI also includes a burst memory that enables snapshots of data from 1-8 channels of selected instruments to be sampled at rates of up to 32 kHz each. The bursts may be triggered by the detection of density depletions, intense electric field wave activity in a given band, lightning detector pulses, or an event at a pre-determined time or location. All VEFI instrument components are working exceptionally well. A description of the instrument, its sensors, and their sampling frequencies and sensitivities will be presented. Representative measurements will be shown.
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Blood Stage Plasmodium falciparum Exhibits Biological Responses to Direct Current Electric Fields
Coronado, Lorena M.; Montealegre, Stephania; Chaverra, Zumara; Mojica, Luis; Espinosa, Carlos; Almanza, Alejandro; Correa, Ricardo; Stoute, José A.; Gittens, Rolando A.
2016-01-01
The development of resistance to insecticides by the vector of malaria and the increasingly faster appearance of resistance to antimalarial drugs by the parasite can dangerously hamper efforts to control and eradicate the disease. Alternative ways to treat this disease are urgently needed. Here we evaluate the in vitro effect of direct current (DC) capacitive coupling electrical stimulation on the biology and viability of Plasmodium falciparum. We designed a system that exposes infected erythrocytes to different capacitively coupled electric fields in order to evaluate their effect on P. falciparum. The effect on growth of the parasite, replication of DNA, mitochondrial membrane potential and level of reactive oxygen species after exposure to electric fields demonstrate that the parasite is biologically able to respond to stimuli from DC electric fields involving calcium signaling pathways. PMID:27537497
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Blood Stage Plasmodium falciparum Exhibits Biological Responses to Direct Current Electric Fields.
Coronado, Lorena M; Montealegre, Stephania; Chaverra, Zumara; Mojica, Luis; Espinosa, Carlos; Almanza, Alejandro; Correa, Ricardo; Stoute, José A; Gittens, Rolando A; Spadafora, Carmenza
2016-01-01
The development of resistance to insecticides by the vector of malaria and the increasingly faster appearance of resistance to antimalarial drugs by the parasite can dangerously hamper efforts to control and eradicate the disease. Alternative ways to treat this disease are urgently needed. Here we evaluate the in vitro effect of direct current (DC) capacitive coupling electrical stimulation on the biology and viability of Plasmodium falciparum. We designed a system that exposes infected erythrocytes to different capacitively coupled electric fields in order to evaluate their effect on P. falciparum. The effect on growth of the parasite, replication of DNA, mitochondrial membrane potential and level of reactive oxygen species after exposure to electric fields demonstrate that the parasite is biologically able to respond to stimuli from DC electric fields involving calcium signaling pathways.
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The Vector Electric Field Instrument on the C/NOFS Satellite
NASA Technical Reports Server (NTRS)
Pfaff, R.; Kujawski, J.; Uribe, P.; Bromund, K.; Fourre, R.; Acuna, M.; Le, G.; Farrell, W.; Holzworth, R.; McCarthy, M.;
2008-01-01
We provide an overview of the Vector Electric Field Instrument (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. VEFI is a NASA GSFC instrument designed 1) to investigate the role of the ambient electric fields in initiating nighttime ionospheric density depletions and turbulence; 2) to determine the electric fields associated with abrupt, large amplitude, density depletions and 3) to quantify the spectrum of the wave electric fields and plasma densities (irregularities) associated with density depletions or Equatorial Spread-F. The VEFI instrument includes a vector electric field double probe detector, a Langmuir trigger probe, a flux gate magnetometer, a lightning detector and associated electronics. The heart of the instrument is the set of double probe detectors designed to measure DC and AC electric fields using 6 identical, mutually orthogonal, deployable 9.5 m booms tipped with 10 cm diameter spheres containing embedded preamplifiers. A description of the instrument and its sensors will be presented. If available, representative measurements will be provided.
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NASA Technical Reports Server (NTRS)
Pfaff, R.; Freudenreich, H.; Bromund, K.; Klenzing, J.; Rowland, D.; Maynard, N.
2010-01-01
Initial results are presented from the Vector Electric Field Investigation (VEFI) on the Air Force Communication/Navigation Outage Forecasting System (C/NOFS) satellite, a mission designed to understand, model, and forecast the presence of equatorial ionospheric irregularities. The VEFI instrument includes a vector DC electric field detector, a fixed-bias Langmuir probe operating in the ion saturation regime, a flux gate magnetometer, an optical lightning detector, and associated electronics including a burst memory. Compared to data obtained during more active solar conditions, the ambient DC electric fields and their associated E x B drifts are variable and somewhat weak, typically < 1 mV/m. Although average drift directions show similarities to those previously reported, eastward/outward during day and westward/downward at night, this pattern varies significantly with longitude and is not always present. Daytime vertical drifts near the magnetic equator are largest after sunrise, with smaller average velocities after noon. Little or no pre-reversal enhancement in the vertical drift near sunset is observed, attributable to the solar minimum conditions creating a much reduced neutral dynamo at the satellite altitude. The nighttime ionosphere is characterized by larger amplitude, structured electric fields, even where the plasma density appears nearly quiescent. Data from successive orbits reveal that the vertical drifts and plasma density are both clearly organized with longitude. The spread-F density depletions and corresponding electric fields that have been detected thus far have displayed a preponderance to appear between midnight and dawn. Associated with the narrow plasma depletions that are detected are broad spectra of electric field and plasma density irregularities for which a full vector set of measurements is available for detailed study. Finally, the data set includes a wide range of ELF/VLF/HF oscillations corresponding to a variety of plasma waves, in particular banded ELF hiss, whistlers, and lower hybrid wave turbulence triggered by lightning-induced sferics. The VEFI data represents a new set of measurements that are germane to numerous fundamental aspects of the electrodynamics and irregularities inherent to the Earth's low latitude ionosphere.
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NASA Astrophysics Data System (ADS)
Zhao, Tingkai; Ji, Xianglin; Jin, Wenbo; Yang, Wenbo; Zhao, Xing; Dang, Alei; Li, Hao; Li, Tiehu
2017-02-01
Semiconducting single-walled carbon nanotubes (s-SWCNTs) were in situ synthesized by a temperature-controlled arc discharging furnace with DC electric field using Co-Ni alloy powder as catalyst in helium gas. The microstructures of s-SWCNTs were characterized using high-resolution transmission electron microscopy, electron diffraction, and Raman spectrometry apparatus. The experimental results indicated that the best voltage value in DC electric field is 54 V, and the environmental temperature of the reaction chamber is 600 °C. The mean diameter of s-SWCNTs was estimated about 1.3 nm. The chiral vector ( n, m) of s-SWCNTs was calculated to be (10, 10) type according to the electron diffraction patterns.
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Martin, James E.; Solis, Kyle Jameson
2015-11-09
It has recently been reported that two types of triaxial electric or magnetic fields can drive vorticity in dielectric or magnetic particle suspensions, respectively. The first type-symmetry -- breaking rational fields -- consists of three mutually orthogonal fields, two alternating and one dc, and the second type -- rational triads -- consists of three mutually orthogonal alternating fields. In each case it can be shown through experiment and theory that the fluid vorticity vector is parallel to one of the three field components. For any given set of field frequencies this axis is invariant, but the sign and magnitude ofmore » the vorticity (at constant field strength) can be controlled by the phase angles of the alternating components and, at least for some symmetry-breaking rational fields, the direction of the dc field. In short, the locus of possible vorticity vectors is a 1-d set that is symmetric about zero and is along a field direction. In this paper we show that continuous, 3-d control of the vorticity vector is possible by progressively transitioning the field symmetry by applying a dc bias along one of the principal axes. Such biased rational triads are a combination of symmetry-breaking rational fields and rational triads. A surprising aspect of these transitions is that the locus of possible vorticity vectors for any given field bias is extremely complex, encompassing all three spatial dimensions. As a result, the evolution of a vorticity vector as the dc bias is increased is complex, with large components occurring along unexpected directions. More remarkable are the elaborate vorticity vector orbits that occur when one or more of the field frequencies are detuned. As a result, these orbits provide the basis for highly effective mixing strategies wherein the vorticity axis periodically explores a range of orientations and magnitudes.« less
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Do, Ltk; Wittayarat, M; Terazono, T; Sato, Y; Taniguchi, M; Tanihara, F; Takemoto, T; Kazuki, Y; Kazuki, K; Oshimura, M; Otoi, T
2016-12-01
The current applications for cat cloning include production of models for the study of human and animal diseases. This study was conducted to investigate the optimal fusion protocol on in vitro development of transgenic cloned cat embryos by comparing duration of electric pulse. Cat fibroblast cells containing a human artificial chromosome (HAC) vector were used as genetically modified nuclear donor cells. Couplets were fused and activated simultaneously with a single DC pulse of 3.0 kV/cm for either 30 or 60 μs. Low rates of fusion and embryo development to the blastocyst stage were observed in the reconstructed HAC-transchromosomic embryos, when the duration of fusion was prolonged to 60 μs. In contrast, the prolongation of electric pulse duration improved the embryo development and quality in the reconstructed control embryos without HAC vector. Our results suggested that the optimal parameters of electric pulses for fusion in cat somatic cell nuclear transfer vary among the types used for donor cells. © 2016 Blackwell Verlag GmbH.
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USDA-ARS?s Scientific Manuscript database
Until recently, most Electrical Penetration Graph (EPG) studies have emphasized small-bodied sternorrhynchans, auchenorrhynchans, and thrips. EPG holds the potential to significantly improve research on a wider array of species, such as large heteropterans and blood-sucking vectors of medical/veteri...
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Estimation of Faults in DC Electrical Power System
NASA Technical Reports Server (NTRS)
Gorinevsky, Dimitry; Boyd, Stephen; Poll, Scott
2009-01-01
This paper demonstrates a novel optimization-based approach to estimating fault states in a DC power system. Potential faults changing the circuit topology are included along with faulty measurements. Our approach can be considered as a relaxation of the mixed estimation problem. We develop a linear model of the circuit and pose a convex problem for estimating the faults and other hidden states. A sparse fault vector solution is computed by using 11 regularization. The solution is computed reliably and efficiently, and gives accurate diagnostics on the faults. We demonstrate a real-time implementation of the approach for an instrumented electrical power system testbed, the ADAPT testbed at NASA ARC. The estimates are computed in milliseconds on a PC. The approach performs well despite unmodeled transients and other modeling uncertainties present in the system.
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Chebabhi, Ali; Fellah, Mohammed Karim; Kessal, Abdelhalim; Benkhoris, Mohamed F
2016-07-01
In this paper is proposed a new balancing three-level three dimensional space vector modulation (B3L-3DSVM) strategy which uses a redundant voltage vectors to realize precise control and high-performance for a three phase three-level four-leg neutral point clamped (NPC) inverter based Shunt Active Power Filter (SAPF) for eliminate the source currents harmonics, reduce the magnitude of neutral wire current (eliminate the zero-sequence current produced by single-phase nonlinear loads), and to compensate the reactive power in the three-phase four-wire electrical networks. This strategy is proposed in order to gate switching pulses generation, dc bus voltage capacitors balancing (conserve equal voltage of the two dc bus capacitors), and to switching frequency reduced and fixed of inverter switches in same times. A Nonlinear Back Stepping Controllers (NBSC) are used for regulated the dc bus voltage capacitors and the SAPF injected currents to robustness, stabilizing the system and to improve the response and to eliminate the overshoot and undershoot of traditional PI (Proportional-Integral). Conventional three-level three dimensional space vector modulation (C3L-3DSVM) and B3L-3DSVM are calculated and compared in terms of error between the two dc bus voltage capacitors, SAPF output voltages and THDv, THDi of source currents, magnitude of source neutral wire current, and the reactive power compensation under unbalanced single phase nonlinear loads. The success, robustness, and the effectiveness of the proposed control strategies are demonstrated through simulation using Sim Power Systems and S-Function of MATLAB/SIMULINK. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.
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NASA Astrophysics Data System (ADS)
Kunisetti, V. Praveen Kumar; Thippiripati, Vinay Kumar
2018-01-01
Open End Winding Induction Motors (OEWIM) are popular for electric vehicles, ship propulsion applications due to less DC link voltage. Electric vehicles, ship propulsions require ripple free torque. In this article, an enhanced three-level voltage switching state scheme for direct torque controlled OEWIM drive is implemented to reduce torque and flux ripples. The limitations of conventional Direct Torque Control (DTC) are: possible problems during low speeds and starting, it operates with variable switching frequency due to hysteresis controllers and produces higher torque and flux ripple. The proposed DTC scheme can abate the problems of conventional DTC with an enhanced voltage switching state scheme. The three-level inversion was obtained by operating inverters with equal DC-link voltages and it produces 18 voltage space vectors. These 18 vectors are divided into low and high frequencies of operation based on rotor speed. The hardware results prove the validity of proposed DTC scheme during steady-state and transients. From simulation and experimental results, proposed DTC scheme gives less torque and flux ripples on comparison to two-level DTC. The proposed DTC is implemented using dSPACE DS-1104 control board interface with MATLAB/SIMULINK-RTI model.
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NASA Astrophysics Data System (ADS)
Kunisetti, V. Praveen Kumar; Thippiripati, Vinay Kumar
2018-06-01
Open End Winding Induction Motors (OEWIM) are popular for electric vehicles, ship propulsion applications due to less DC link voltage. Electric vehicles, ship propulsions require ripple free torque. In this article, an enhanced three-level voltage switching state scheme for direct torque controlled OEWIM drive is implemented to reduce torque and flux ripples. The limitations of conventional Direct Torque Control (DTC) are: possible problems during low speeds and starting, it operates with variable switching frequency due to hysteresis controllers and produces higher torque and flux ripple. The proposed DTC scheme can abate the problems of conventional DTC with an enhanced voltage switching state scheme. The three-level inversion was obtained by operating inverters with equal DC-link voltages and it produces 18 voltage space vectors. These 18 vectors are divided into low and high frequencies of operation based on rotor speed. The hardware results prove the validity of proposed DTC scheme during steady-state and transients. From simulation and experimental results, proposed DTC scheme gives less torque and flux ripples on comparison to two-level DTC. The proposed DTC is implemented using dSPACE DS-1104 control board interface with MATLAB/SIMULINK-RTI model.
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Modeling and control of fuel cell based distributed generation systems
NASA Astrophysics Data System (ADS)
Jung, Jin Woo
This dissertation presents circuit models and control algorithms of fuel cell based distributed generation systems (DGS) for two DGS topologies. In the first topology, each DGS unit utilizes a battery in parallel to the fuel cell in a standalone AC power plant and a grid-interconnection. In the second topology, a Z-source converter, which employs both the L and C passive components and shoot-through zero vectors instead of the conventional DC/DC boost power converter in order to step up the DC-link voltage, is adopted for a standalone AC power supply. In Topology 1, two applications are studied: a standalone power generation (Single DGS Unit and Two DGS Units) and a grid-interconnection. First, dynamic model of the fuel cell is given based on electrochemical process. Second, two full-bridge DC to DC converters are adopted and their controllers are designed: an unidirectional full-bridge DC to DC boost converter for the fuel cell and a bidirectional full-bridge DC to DC buck/boost converter for the battery. Third, for a three-phase DC to AC inverter without or with a Delta/Y transformer, a discrete-time state space circuit model is given and two discrete-time feedback controllers are designed: voltage controller in the outer loop and current controller in the inner loop. And last, for load sharing of two DGS units and power flow control of two DGS units or the DGS connected to the grid, real and reactive power controllers are proposed. Particularly, for the grid-connected DGS application, a synchronization issue between an islanding mode and a paralleling mode to the grid is investigated, and two case studies are performed. To demonstrate the proposed circuit models and control strategies, simulation test-beds using Matlab/Simulink are constructed for each configuration of the fuel cell based DGS with a three-phase AC 120 V (L-N)/60 Hz/50 kVA and various simulation results are presented. In Topology 2, this dissertation presents system modeling, modified space vector PWM implementation (MSVPWM) and design of a closed-loop controller of the Z-source converter which utilizes L and C components and shoot-through zero vectors for the standalone AC power generation. The fuel cell system is modeled by an electrical R-C circuit in order to include slow dynamics of the fuel cells and a voltage-current characteristic of a cell is also considered. A discrete-time state space model is derived to implement digital control and a space vector pulse-width modulation (SVPWM) technique is modified to realize the shoot-through zero vectors that boost the DC-link voltage. Also, three discrete-time feedback controllers are designed: a discrete-time optimal voltage controller, a discrete-time sliding mode current controller, and a discrete-time PI DC-link voltage controller. Furthermore, an asymptotic observer is used to reduce the number of sensors and enhance the reliability of the system. To demonstrate the analyzed circuit model and proposed control strategy, various simulation results using Matlab/Simulink are presented under both light/heavy loads and linear/nonlinear loads for a three-phase AC 208 V (L-L)/60 Hz/10 kVA.
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NASA Technical Reports Server (NTRS)
Hamilton, H. B.; Strangas, E.
1980-01-01
The time dependent solution of the magnetic field is introduced as a method for accounting for the variation, in time, of the machine parameters in predicting and analyzing the performance of the electrical machines. The method of time dependent finite element was used in combination with an also time dependent construction of a grid for the air gap region. The Maxwell stress tensor was used to calculate the airgap torque from the magnetic vector potential distribution. Incremental inductances were defined and calculated as functions of time, depending on eddy currents and saturation. The currents in all the machine circuits were calculated in the time domain based on these inductances, which were continuously updated. The method was applied to a chopper controlled DC series motor used for electric vehicle drive, and to a salient pole sychronous motor with damper bars. Simulation results were compared to experimentally obtained ones.
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Variable-speed wind power system with improved energy capture via multilevel conversion
Erickson, Robert W.; Al-Naseem, Osama A.; Fingersh, Lee Jay
2005-05-31
A system and method for efficiently capturing electrical energy from a variable-speed generator are disclosed. The system includes a matrix converter using full-bridge, multilevel switch cells, in which semiconductor devices are clamped to a known constant DC voltage of a capacitor. The multilevel matrix converter is capable of generating multilevel voltage wave waveform of arbitrary magnitude and frequencies. The matrix converter can be controlled by using space vector modulation.
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Perreau, Matthieu; Mennechet, Franck; Serratrice, Nicolas; Glasgow, Joel N.; Curiel, David T.; Wodrich, Harald; Kremer, Eric J.
2007-01-01
Antipathogen immune responses create a balance between immunity, tolerance, and immune evasion. However, during gene therapy most viral vectors are delivered in substantial doses and are incapable of expressing gene products that reduce the host's ability to detect transduced cells. Gene transfer efficacy is also modified by the in vivo transduction of dendritic cells (DC), which notably increases the immunogenicity of virions and vector-encoded genes. In this study, we evaluated parameters that are relevant to the use of canine adenovirus serotype 2 (CAV-2) vectors in the clinical setting by assaying their effect on human monocyte-derived DC (hMoDC). We compared CAV-2 to human adenovirus (HAd) vectors containing the wild-type virion, functional deletions in the penton base RGD motif, and the CAV-2 fiber knob. In contrast to the HAd type 5 (HAd5)-based vectors, CAV-2 poorly transduced hMoDC, provoked minimal upregulation of major histocompatibility complex class I/II and costimulatory molecules (CD40, CD80, and CD86), and induced negligible morphological changes indicative of DC maturation. Functional maturation assay results (e.g., reduced antigen uptake; tumor necrosis factor alpha, interleukin-1β [IL-1β], gamma interferon [IFN-γ], IL-10, IL-12, and IFN-α/β secretion; and stimulation of heterologous T-cell proliferation) were also significantly lower for CAV-2. Our data suggested that this was due, in part, to the use of an alternative receptor and a block in vesicular escape. Additionally, HAd5 vector-induced hMoDC maturation was independent of the aforementioned cytokines. Paradoxically, an HAd5/CAV-2 hybrid vector induced the greatest phenotypical and functional maturation of hMoDC. Our data suggest that CAV-2 and the HAd5/CAV-2 vector may be the antithesis of Adenoviridae immunogenicity and that each may have specific clinical advantages. PMID:17229706
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NASA Technical Reports Server (NTRS)
Mach, D. M.; Koshak, W. J.
2007-01-01
A matrix calibration procedure has been developed that uniquely relates the electric fields measured at the aircraft with the external vector electric field and net aircraft charge. The calibration method can be generalized to any reasonable combination of electric field measurements and aircraft. A calibration matrix is determined for each aircraft that represents the individual instrument responses to the external electric field. The aircraft geometry and configuration of field mills (FMs) uniquely define the matrix. The matrix can then be inverted to determine the external electric field and net aircraft charge from the FM outputs. A distinct advantage of the method is that if one or more FMs need to be eliminated or deemphasized [e.g., due to a malfunction), it is a simple matter to reinvert the matrix without the malfunctioning FMs. To demonstrate the calibration technique, data are presented from several aircraft programs (ER-2, DC-8, Altus, and Citation).
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NASA Technical Reports Server (NTRS)
Ludwig, Kimberly; Mackin, Michael; Wright, Theodore
1991-01-01
The authors describe the Ada language software developed to perform the electrical power system monitoring functions for the NASA Lewis Research Center's Power Management and Distribution (PMAD) DC testbed. The results of the effort to implement this monitor are presented. The PMAD DC testbed is a reduced-scale prototype of the electric power system to be used in Space Station Freedom. The power is controlled by smart switches known as power control components (or switchgear). The power control components are currently coordinated by five Compaq 386/20e computers connected through an 802.4 local area network. The power system monitor algorithm comprises several functions, including periodic data acquisition, data smoothing, system performance analysis, and status reporting. Data are collected from the switchgear sensors every 100 ms, then passed through a 2-Hz digital filter. System performance analysis includes power interruption and overcurrent detection. The system monitor required a hardware timer interrupt to activate the data acquisition function. The execution time of the code was optimized by using an assembly language routine. The routine allows direct vectoring of the processor to Ada language procedures that perform periodic control activities.
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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.
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NASA Technical Reports Server (NTRS)
Le, Guan; Pfaff, Rob; Kepko, Larry; Rowland, Doug; Bromund, Ken; Freudenreich, Henry; Martin, Steve; Liebrecht, C.; Maus, S.
2010-01-01
The Vector Electric Field Investigation (VEFI) suite onboard the Communications/Navigation Outage Forecasting System (C/NOFS) spacecraft includes a sensitive fluxgate magnetometer to measure DC and ULF magnetic fields in the low latitude ionosphere. The instrument includes a DC vector measurement at 1 sample/sec with a range of +/- 45,000 nT whose primary objective is to provide direct measurements of both V x B and E x B that are more accurate than those obtained using a simple magnetic field model. These data can also be used for scientific research to provide information of large-scale ionospheric and magnetospheric current systems, which, when analyzed in conjunction with the C/NOFS DC electric field measurements, promise to advance our understanding of the electrodynamics of the low latitude ionosphere. In this study, we use the magnetic field data to study the temporal and local time variations of the ring currents during geomagnetic storms. We first compare the in situ measurements with the POMME (the POtsdam Magnetic Model of the Earth) model in order to provide an in-flight "calibration" of the data as well as compute magnetic field residuals essential for revealing large scale external current systems. We then compare the magnetic field residuals observed both during quiet times and during geomagnetic storms at the same geographic locations to deduce the magnetic field signatures of the ring current. As will be shown, the low inclination of the C/NOFS satellite provides a unique opportunity to study the evolution of the ring current as a function of local time, which is particularly insightful during periods of magnetic storms. This paper will present the initial results of this study.
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Guzman, Efrain; Taylor, Geraldine; Hope, Jayne; Herbert, Rebecca; Cubillos-Zapata, Carolina; Charleston, Bryan
2016-10-01
Dendritic cells (DC) are central to the initiation of immune responses, and various approaches have been used to target vaccines to DC in order to improve immunogenicity. Cannulation of lymphatic vessels allows for the collection of DC that migrate from the skin. These migrating DC are involved in antigen uptake and presentation following vaccination. Human replication-deficient adenovirus (AdV) 5 is a promising vaccine vector for delivery of recombinant antigens. Although the mechanism of AdV attachment and penetration has been extensively studied in permissive cell lines, few studies have addressed the interaction of AdV with DC. In this study, we investigated the interaction of bovine skin-migrating DC and replication-deficient AdV-based vaccine vectors. We found that, despite lack of expression of Coxsackie B-Adenovirus Receptor and other known adenovirus receptors, AdV readily enters skin-draining DC via an actin-dependent endocytosis. Virus exit from endosomes was pH independent, and neutralizing antibodies did not prevent virus entry but did prevent virus translocation to the nucleus. We also show that combining adenovirus with adjuvant increases the absolute number of intracellular virus particles per DC but not the number of DC containing intracellular virus. This results in increased trans-gene expression and antigen presentation. We propose that, in the absence of Coxsackie B-Adenovirus Receptor and other known receptors, AdV5-based vectors enter skin-migrating DC using actin-dependent endocytosis which occurs in skin-migrating DC, and its relevance to vaccination strategies and vaccine vector targeting is discussed.
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General Matrix Inversion for the Calibration of Electric Field Sensor Arrays on Aircraft Platforms
NASA Technical Reports Server (NTRS)
Mach, D. M.; Koshak, W. J.
2006-01-01
We have developed a matrix calibration procedure that uniquely relates the electric fields measured at the aircraft with the external vector electric field and net aircraft charge. Our calibration method is being used with all of our aircraft/electric field sensing combinations and can be generalized to any reasonable combination of electric field measurements and aircraft. We determine a calibration matrix that represents the individual instrument responses to the external electric field. The aircraft geometry and configuration of field mills (FMs) uniquely define the matrix. The matrix can then be inverted to determine the external electric field and net aircraft charge from the FM outputs. A distinct advantage of the method is that if one or more FMs need to be eliminated or de-emphasized (for example, due to a malfunction), it is a simple matter to reinvert the matrix without the malfunctioning FMs. To demonstrate our calibration technique, we present data from several of our aircraft programs (ER-2, DC-8, Altus, Citation).
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Hybrid electric vehicle power management system
Bissontz, Jay E.
2015-08-25
Level voltage levels/states of charge are maintained among a plurality of high voltage DC electrical storage devices/traction battery packs that are arrayed in series to support operation of a hybrid electric vehicle drive train. Each high voltage DC electrical storage device supports a high voltage power bus, to which at least one controllable load is connected, and at least a first lower voltage level electrical distribution system. The rate of power transfer from the high voltage DC electrical storage devices to the at least first lower voltage electrical distribution system is controlled by DC-DC converters.
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Campbell, Jeremy B; Newson, Steve
2013-02-26
Embodiments of DC source assemblies of power inverter systems of the type suitable for deployment in a vehicle having an electrically grounded chassis are provided. An embodiment of a DC source assembly comprises a housing, a DC source disposed within the housing, a first terminal, and a second terminal. The DC source also comprises a first capacitor having a first electrode electrically coupled to the housing, and a second electrode electrically coupled to the first terminal. The DC source assembly further comprises a second capacitor having a first electrode electrically coupled to the housing, and a second electrode electrically coupled to the second terminal.
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NASA Astrophysics Data System (ADS)
Bhattacharjee, N.; Horowitz, L. F.; Folch, A.
2016-10-01
Concerns over biosafety, cost, and carrying capacity of viral vectors have accelerated research into physical techniques for gene delivery such as electroporation and mechanoporation. Advances in microfabrication have made it possible to create high electric fields over microscales, resulting in more efficient DNA delivery and higher cell viability. Continuous-flow microfluidic methods are typically more suitable for cellular therapies where a large number of cells need to be transfected under sterile conditions. However, the existing continuous-flow designs used to generate multiple pulses either require expensive peripherals such as high-voltage (>400 V) sources or function generators, or result in reduced cell viability due to the proximity of the cells to the electrodes. In this paper, we report a continuous-flow microfluidic device whose channel geometry reduces instrumentation demands and minimizes cellular toxicity. Our design can generate multiple pulses of high DC electric field strength using significantly lower voltages (15-60 V) than previous designs. The cells flow along a serpentine channel that repeatedly flips the cells between a cathode and an anode at high throughput. The cells must flow through a constriction each time they pass from an anode to a cathode, exposing them to high electric field strength for short durations of time (the "pulse-width"). A conductive biocompatible poly-aniline hydrogel network formed in situ is used to apply the DC voltage without bringing the metal electrodes close to the cells, further sheltering cells from the already low voltage electrodes. The device was used to electroporate multiple cell lines using electric field strengths between 700 and 800 V/cm with transfection efficiencies superior than previous flow-through designs.
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Bhattacharjee, N; Horowitz, L F; Folch, A
2016-10-17
Concerns over biosafety, cost, and carrying capacity of viral vectors have accelerated research into physical techniques for gene delivery such as electroporation and mechanoporation. Advances in microfabrication have made it possible to create high electric fields over microscales, resulting in more efficient DNA delivery and higher cell viability. Continuous-flow microfluidic methods are typically more suitable for cellular therapies where a large number of cells need to be transfected under sterile conditions. However, the existing continuous-flow designs used to generate multiple pulses either require expensive peripherals such as high-voltage (>400 V) sources or function generators, or result in reduced cell viability due to the proximity of the cells to the electrodes. In this paper, we report a continuous-flow microfluidic device whose channel geometry reduces instrumentation demands and minimizes cellular toxicity. Our design can generate multiple pulses of high DC electric field strength using significantly lower voltages (15-60 V) than previous designs. The cells flow along a serpentine channel that repeatedly flips the cells between a cathode and an anode at high throughput. The cells must flow through a constriction each time they pass from an anode to a cathode, exposing them to high electric field strength for short durations of time (the "pulse-width"). A conductive biocompatible poly-aniline hydrogel network formed in situ is used to apply the DC voltage without bringing the metal electrodes close to the cells, further sheltering cells from the already low voltage electrodes. The device was used to electroporate multiple cell lines using electric field strengths between 700 and 800 V/cm with transfection efficiencies superior than previous flow-through designs.
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The FIELDS Instrument Suite on MMS: Scientific Objectives, Measurements, and Data Products
NASA Astrophysics Data System (ADS)
Torbert, R. B.; Russell, C. T.; Magnes, W.; Ergun, R. E.; Lindqvist, P.-A.; Le Contel, O.; Vaith, H.; Macri, J.; Myers, S.; Rau, D.; Needell, J.; King, B.; Granoff, M.; Chutter, M.; Dors, I.; Olsson, G.; Khotyaintsev, Y. V.; Eriksson, A.; Kletzing, C. A.; Bounds, S.; Anderson, B.; Baumjohann, W.; Steller, M.; Bromund, K.; Le, Guan; Nakamura, R.; Strangeway, R. J.; Leinweber, H. K.; Tucker, S.; Westfall, J.; Fischer, D.; Plaschke, F.; Porter, J.; Lappalainen, K.
2016-03-01
The FIELDS instrumentation suite on the Magnetospheric Multiscale (MMS) mission provides comprehensive measurements of the full vector magnetic and electric fields in the reconnection regions investigated by MMS, including the dayside magnetopause and the night-side magnetotail acceleration regions out to 25 Re. Six sensors on each of the four MMS spacecraft provide overlapping measurements of these fields with sensitive cross-calibrations both before and after launch. The FIELDS magnetic sensors consist of redundant flux-gate magnetometers (AFG and DFG) over the frequency range from DC to 64 Hz, a search coil magnetometer (SCM) providing AC measurements over the full whistler mode spectrum expected to be seen on MMS, and an Electron Drift Instrument (EDI) that calibrates offsets for the magnetometers. The FIELDS three-axis electric field measurements are provided by two sets of biased double-probe sensors (SDP and ADP) operating in a highly symmetric spacecraft environment to reduce significantly electrostatic errors. These sensors are complemented with the EDI electric measurements that are free from all local spacecraft perturbations. Cross-calibrated vector electric field measurements are thus produced from DC to 100 kHz, well beyond the upper hybrid resonance whose frequency provides an accurate determination of the local electron density. Due to its very large geometric factor, EDI also provides very high time resolution (˜1 ms) ambient electron flux measurements at a few selected energies near 1 keV. This paper provides an overview of the FIELDS suite, its science objectives and measurement requirements, and its performance as verified in calibration and cross-calibration procedures that result in anticipated errors less than 0.1 nT in B and 0.5 mV/m in E. Summaries of data products that result from FIELDS are also described, as well as algorithms for cross-calibration. Details of the design and performance characteristics of AFG/DFG, SCM, ADP, SDP, and EDI are provided in five companion papers.
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Bidirectional DC-DC conversion device use at system of urban electric transport
NASA Astrophysics Data System (ADS)
Vilberger, M. E.; Vislogusov, D. P.; Kotin, D. A.; Kulekina, A. V.
2017-10-01
The paper considers questions of energy storage devices used in electric transport, especially in the electric traction drive of a trolley bus, in order to provide an autonomous motion, overhead system’s load leveling and energy recovering. For efficiency of the proposed system, a bidirectional DC-DC converter is used. During the simulation, regulation characteristics of the bidirectional DC-DC converters were obtained.
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Isolated and soft-switched power converter
Peng, Fang Zheng; Adams, Donald Joe
2002-01-01
An isolated and soft-switched power converter is used for DC/DC and DC/DC/AC power conversion. The power converter includes two resonant tank circuits coupled back-to-back through an isolation transformer. Each resonant tank circuit includes a pair of resonant capacitors connected in series as a resonant leg, a pair of tank capacitors connected in series as a tank leg, and a pair of switching devices with anti-parallel clamping diodes coupled in series as resonant switches and clamping devices for the resonant leg. The power converter is well suited for DC/DC and DC/DC/AC power conversion applications in which high-voltage isolation, DC to DC voltage boost, bidirectional power flow, and a minimal number of conventional switching components are important design objectives. For example, the power converter is especially well suited to electric vehicle applications and load-side electric generation and storage systems, and other applications in which these objectives are important. The power converter may be used for many different applications, including electric vehicles, hybrid combustion/electric vehicles, fuel-cell powered vehicles with low-voltage starting, remote power sources utilizing low-voltage DC power sources, such as photovoltaics and others, electric power backup systems, and load-side electric storage and generation systems.
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Pan, Jian-ping; Weng, Yue-song; Wu, Qian-qian
2006-09-01
To investigate the anti-metastatic effect of vascular endothelial growth factor receptor 2 extracellular domain gene-modified dendritic cell (DC-sVEGFR-2) vaccination. Dendritic cells (DC) were electroporated with pcDNA3. 1/sVEGFR-2 plasmid DNA. Expression of sVEGFR-2 was determined by ELISA. For immunization, C57BL/6 mice were intravenously injected three times with 1 x 10(5) cells per mouse of DC, pcDNA3. 1-transfected DC (DC-vector) , DC-sVEGFR-2, or 100 microl of PBS at 7-day intervals. At 10 days after the last immunization, the immunized mice were subjected to assessment of cytotoxic T lymphocyte ( CTL) response to VEGFR-2, alginate bead analysis of tumor cell-induced angiogenesis, and observation of the anti-metastatic effect in B16 melanoma metastasis model. CTL activity was determined by a standard 4-h 51Cr release assay against VEGFR-2 + vascular endothelial cell line H5V, 3LL cells stably transfected with pcDNA3. 1/sVEGFR-2 (3LL,-sVEGFR-2), and VEGFR-2- cell lines EL-4 and 3LL. Monoclonal antibodies GK1.5 anti-CD4 and 2.43 anti-CD8 were used to deplete in vivo CD4 + T cells and CD8' T cells, respectively. DC-sVEGFR-2 could effectively express sVEGFR-2, whereas DC-vector and DC could not. Immunization of mice with DC-sVEGFR-2 significantly induce CTL activity against VEGFR-2 + cell lines H5V and 3LL-sVEGFR-2, however, no significant CTL activity was observed when VEGFR-2- syngeneic cell lines EL-4 and 3LL. were used as target cells, implying this CTL activity was VEGFR-2 specific. Alginate bead analysis of in vivo neoangiogenesis showed that the inhibition reached 50% in mice vaccinated with DC-sVEGFR-2 compared with mice vaccinated with DC, DC-vector or PBS. Anti-metastatic experiment showed that profound reduction in pulmonary metastases was found in mice immunized with DC-sVEGFR-2, while mice immunized with PBS, DC, DC-vector developed extensive pulmonary metastases. The number of tumor nodules on lung surface decreased by 81.9% in mice immunized with DC-sVEGFR-2 when compared with mice immunized with DC-vector (49.7+/-12.7 vs. 9.0+/-3.2). In vivo T cell subset depletion experiments showed that the anti-metastatic effect of DC-sVEGFR-2 vaccination was abrogated in CD8 + T cell-depleted but not in CD4+ T cell-depleted mice. Immunization of mice with DC-sVEGFR-2 could break self-tolerance and induce a significant CTL response to VEGFR-2, leading to profound inhibition of tumor-cell induced angiogenesis and metastasis. This anti-metastatic effect is mainly mediated by CD8+ T cells.
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HIV-derived vectors for gene therapy targeting dendritic cells.
Rossetti, Maura; Cavarelli, Mariangela; Gregori, Silvia; Scarlatti, Gabriella
2013-01-01
Human immunodeficiency virus type 1 (HIV-1)-derived lentiviral vectors (LV) have the potential to mediate stable therapeutic gene transfer. However, similarly to other viral vectors, their benefit is compromised by the induction of an immune response toward transgene-expressing cells that closely mimics antiviral immunity. LV share with the parental HIV the ability to activate dendritic cells (DC), while lack the peculiar ability of subverting DC functions, which is responsible for HIV immune escape. Understanding the interaction between LV and DC, with plasmacytoid and myeloid DC playing fundamental and distinct roles, has paved the way to novel approaches aimed at regulating transgene-specific immune responses. Thanks to the ability to target either DC subsets LV might be a powerful tool to induce immunity (i.e., gene therapy of cancer), cell death (i.e., in HIV/AIDS infection), or tolerance (i.e., gene therapy strategies for monogenic diseases). In this chapter, similarities and differences between the LV-mediated and HIV-mediated induction of immune responses, with specific focus on their interactions with DC, are discussed.
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Burckbuchler, V; Wintgens, V; Lecomte, S; Percot, A; Leborgne, C; Danos, O; Kichler, A; Amiel, C
2006-04-05
The ability of DNA to bind polycation yielding polyplexes is widely used in nonviral gene delivery. The aim of the present study was to evaluate the DNA compaction with a new DNA vector using Raman spectroscopy. The polyplexes result from an association of a beta-cyclodextrin polymer (polybeta-CD), an amphiphilic cationic connector (DC-Chol or adamantane derivative Ada2), and DNA. The charge of the polymeric vector is effectively controlled by simple addition of cationic connector in the medium. We used surface enhanced Raman spectroscopy (SERS) to characterize this ternary complex, monitoring the accessibility of adenyl residues to silver colloids. The first experiments were performed using model systems based on polyA (polyadenosine monophosphate) well characterized by SERS. This model was then extended to plasmid DNA to study polybeta-CD/Ada2/DNA and polybeta-CD/DC-Chol/DNA polyplexes. The SERS spectra show a decrease of signal intensity when the vector/DNA charge ratio (Z+/-) increases. At the highest ratio (Z+/- = 10) the signal is 6-fold and 3-fold less intense than the DNA reference signal for Ada2 and DC-Chol polyplexes, respectively. Thus adenyl residues have a reduced accessibility as DNA is bound to the vector. Moreover, the SERS intensity variations are in agreement with gel electrophoresis and zeta potential experiments on the same systems. The overall study clearly demonstrates that the cationic charges neutralizing the negative charges of DNA result in the formation of stable polyplexes. In vitro transfection efficiency of those DNA vectors are also presented and compared to the classical DC-Chol lipoplexes (DC-Chol/DNA). The results show an increase of the transfection efficiency 2-fold higher with our vector based on polybeta-CD. Copyright 2005 Wiley Periodicals, Inc.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-06-01
... determine if a certain fuel pump housing electrical connector is installed. The existing AD also requires a... procedures for disabling certain fuel pump electrical circuits following failure of a fuel pump housing electrical connector if applicable. The existing AD also requires the deactivation of certain fuel tanks or...
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Multi Bus DC-DC Converter in Electric Hybrid Vehicles
NASA Astrophysics Data System (ADS)
Krithika, V.; Subramaniam, C.; Sridharan, R.; Geetha, A.
2018-04-01
This paper is cotncerned with the design, simulation and fabrication of the prototype of a Multi bus DC- DC converter operating from 42V DC and delivering 14V DC and 260V DC. As a result, three DC buses are interconnected through a single power electronic circuitry. Such a requirement is energized in the development of a hybrid electric automobile which uses the technology of fuel cell. This is implemented by using a Bidirectional DC-DC converter configuration which is ideally suitable for multiple outputs with mutual electrical isolation. For the sake of reduced size and cost of step-up transformer, selection of a high frequency switching cycle at 10 KHz was done.
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Characteristics of DC electric fields in transient plasma sheet events
NASA Astrophysics Data System (ADS)
Laakso, H. E.; Escoubet, C. P.; Masson, A.
2015-12-01
We take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer on the four Cluster spacecraft. The calibrated observations of the three spectrometers are used to determine the proton and electron velocity moments. The velocity moments can be used to estimate the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. As the measurement techniques are so different, it is quite plausible that when two different measurements yield the same DC electric field, it is the correct field. All five measurements of the DC electric field are usually not simultaneously available, especially on Cluster 2 where CODIF and HIA are not operational, or on Cluster 4 where EDI is off. In this presentation we investigate DC electric field in various transient plasma sheet events such as dipolarization events and BBF's and how the five measurements agree or disagree. There are plenty of important issues that are considered, e.g., (1) what kind of DC electric fields exist in such events and what are their spatial scales, (2) do electrons and ions perform ExB drift motions in these events, and (3) how well the instruments have been calibrated.
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Onboard power line conditioning system for an electric or hybrid vehicle
Kajouke, Lateef A.; Perisic, Milun
2016-06-14
A power line quality conditioning system for a vehicle includes an onboard rechargeable direct current (DC) energy storage system and an onboard electrical system coupled to the energy storage system. The energy storage system provides DC energy to drive an electric traction motor of the vehicle. The electrical system operates in a charging mode such that alternating current (AC) energy from a power grid external to the vehicle is converted to DC energy to charge the DC energy storage system. The electrical system also operates in a vehicle-to-grid power conditioning mode such that DC energy from the DC energy storage system is converted to AC energy to condition an AC voltage of the power grid.
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Characteristics of DC electric fields at dipolarization fronts
NASA Astrophysics Data System (ADS)
Laakso, Harri; Escoubet, Philippe; Masson, Arnaud
2016-04-01
We investigate the characteristics of DC electric field at dipolarization fronts and BBF's using multi-point Cluster observations. There are plenty of important issues that are considered, such as what kind of DC electric fields exist in such events and what are their spatial scales. One can also recognize if electrons and ions perform ExB drift motions in these events. To investigate this, we take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer. The calibrated observations of the three spectrometers are used to determine the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. This investigation also helps understand how well different measurements are calibrated.
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Mehrotra, Shikhar; Chhabra, Arvind; Chakraborty, Abolokita; Chattopadhyay, Subhasis; Slowik, Mark; Stevens, Robert; Zengou, Ryan; Mathias, Clinton; Butterfield, Lisa H; Dorsky, David I; Economou, James S; Mukherji, Bijay; Chakraborty, Nitya G
2004-01-01
Dendritic cells (DC) play critical roles in generating an immune response and in inducing tolerance. Diverse microenvironmental factors can ‘polarize’ DC toward an immunogenic or non-immunogenic phenotype. Among the various microenvironmental factors, interleukin-10 (IL-10) exhibits a potent immunosuppressive effect on antigen-presenting cells (APC). Here, we show that monocyte-derived DC generated in the presence of IL-10 exhibit a profound down-regulation of many genes that are associated with immune activation and show that the IL-10-grown DC are poor stimulators of CD8+ T cells in a strictly autologous and major histocompatibility complex (MHC) class I-restricted melanoma antigen recognized by T cells (MART-1) epitope presentation system. However, these IL-10-grown DC can efficiently activate the epitope-specific CD8+ T cells when they are made to present the epitope following transduction with an adenoviral vector expressing the MART-1 antigen. In addition, we show that the MART-1 protein colocalizes with the MHC class I protein, equally well, in the iDC and in the DC cultured in presence of IL-10 when both DC types are infected with the viral vector. We also show that the vector transduced DC present the MART-127–35 epitope for a sustained period compared to the peptide pulsed DC. These data suggest that although DCs generated in the presence of IL-10 tend to be non-immunogenic, they are capable of processing and presenting an antigen when the antigen is synthesized within the DC. PMID:15554925
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Engineered Lentivector Targeting of Dendritic Cells for In Vivo Immunization
Yang, Lili; Yang, Haiguang; Rideout, Kendra; Cho, Taehoon; Joo, Kye il; Ziegler, Leslie; Elliot, Abigail; Walls, Anthony; Yu, Dongzi; Baltimore, David; Wang, Pin
2008-01-01
We report a method of inducing antigen production in dendritic cells (DCs) by in vivo targeting with lentiviral vectors that specifically bind to the DC surface protein, DC-SIGN. To target the DCs, the lentivector was enveloped with a viral glycoprotein from Sindbis virus, engineered to be DC-SIGN-specific. In vitro, this lentivector specifically transduced DCs and induced DC maturation. A remarkable frequency (up to 12%) of ovalbumin (OVA)-specific CD8+ T cells and a significant antibody response were observed 2 weeks following injection of a targeted lentiviral vector encoding an OVA transgene into naïve mice. These mice were solidly protected against the growth of the OVA-expressing E.G7 tumor and this methodology could even induce regression of an established tumor. Thus, lentiviral vectors targeting DCs provide a simple method of producing effective immunity and may provide an alternative route for immunization with protein antigens. PMID:18297056
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Singh, Harmohan N.
2012-06-05
A hybrid power system is comprised of a high energy density element such as a fuel-cell and high power density elements such as a supercapacitor banks. A DC/DC converter electrically connected to the fuel cell and converting the energy level of the energy supplied by the fuel cell. A first switch is electrically connected to the DC/DC converter. First and second supercapacitors are electrically connected to the first switch and a second switch. A controller is connected to the first switch and the second switch, monitoring charge levels of the supercapacitors and controls the switching in response to the charge levels. A load is electrically connected to the second switch. The first switch connects the DC/DC converter to the first supercapacitor when the second switch connects the second supercapacitor to the load. The first switch connects the DC/DC converter to the second supercapacitor when the second switch connects the first supercapacitor to the load.
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Combined in-situ and ground-based observations of quasi-periodic radar echoes
NASA Astrophysics Data System (ADS)
Pfaff, R.; Kudeki, E.; Larsen, M.; Clemmons, J.; Earle, G.
A series of combined rocket/radar investigation of the electrodynamics and neutralplasma coupling associated with sporadic-E layers and quasi-periodic backscatter radar echoes has been carried out from launch sites at both Puerto Rico and the Wallops Flight Facility, Virginia (USA) between 1998-2001. The instrumented rockets consisted of main and sub-payloads and were launched while strong quasiperiodic VHF echoes were observed simultaneously with the Univ. of Illinois 50 MHz backscatter radar. The rocket apogee was purposely limited so that the payloads would dwell in the sporadic-E region (90-115 km). The main payload included vector DC and AC electric field detectors, a DC magnetometer, an ion mass spectrometer, an ionization gauge, and spaced-electric field receivers to measure the wavelength and phase velocity of the unstable plasma waves. The sub-payload was instrumented to measure DC and wave electric fields and plasma density. In one case, a separate rocket was launched a few minutes later which released luminous TMA trails to measure the neutral wind, its velocity shear, and embedded neutral structures. In this experiment, the payloads successfully pierced a well-defined, 2-3 km thick metallic sporadic-E layer of approximately 10**5 e/cc near 103 km altitude. In-situ DC electric field measurements revealed ~5mV/m ambient meridional fields above and below the layer with 1-2 mV/m amplitude, large scale structures superimposed. The wavelengths of these structures were approximately 2-4 km and may be related to the seat of the quasiperiodic echoes. Intense (~5 mV/m), higher frequency (shorter scale) broadband waves were also observed in-situ, both above and below the layer, consistent with the VHF backscatter observations during the time of the launch. Neither the large scale nor short scale plasma waves appeared to be distinctly organized by the sporadic-E density layer. The TMA release showed large amplitude (~ 100 m/s) meridional winds near 102-105 km, with the most intense shears directly below these altitudes, where the short scale electric field fluctuations were most intense. We summarize the observations from the different experiments and discuss them in the context of current theories regarding quasi-periodic echoes.
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Combined In-situ and Ground-based Observations of Quasi-periodic Radar Echoes
NASA Astrophysics Data System (ADS)
Pfaff, R.; Kudeki, E.; Larsen, M.; Clemmons, J.; Earle, G.
A series of combined rocket/radar investigation of the electrodynamics and neutral- plasma coupling associated with sporadic-E layers and quasi-periodic backscatter radar echoes has been carried out from launch sites at both Puerto Rico and the Wallops Flight Facility, Virginia (USA) between 1998-2001. The instrumented rock- ets consisted of main and sub-payloads and were launched while strong quasi- periodic VHF echoes were observed simultaneously with the Univ. of Illinois 50 MHz backscatter radar. The rocket apogee was purposely limited so that the payloads would dwell in the sporadic-E region (90-115 km). The main payload included vector DC and AC electric field detectors, a DC magnetometer, an ion mass spectrometer, an ioniza- tion gauge, and spaced-electric field receivers to measure the wavelength and phase velocity of the unstable plasma waves. The sub-payload was instrumented to measure DC and wave electric fields and plasma density. In one case, a separate rocket was launched a few minutes later which released luminous TMA trails to measure the neu- tral wind, its velocity shear, and embedded neutral structures. In this experiment, the payloads successfully pierced a well-defined, 2-3 km thick metallic sporadic-E layer of approximately 10**5 e/cc near 103 km altitude. In-situ DC electric field measure- ments revealed ~5mV/m ambient meridional fields above and below the layer with 1-2 mV/m amplitude, large scale structures superimposed. The wavelengths of these structures were approximately 2-4 km and may be related to the seat of the quasi- periodic echoes. Intense (~5 mV/m), higher frequency (shorter scale) broadband waves were also observed in-situ, both above and below the layer, consistent with the VHF backscatter observations during the time of the launch. Neither the large scale nor short scale plasma waves appeared to be distinctly organized by the sporadic-E den- sity layer. The TMA release showed large amplitude (~ 100 m/s) meridional winds near 102-105 km, with the most intense shears directly below these altitudes, where the short scale electric field fluctuations were most intense. We summarize the ob- servations from the different experiments and discuss them in the context of current theories regarding quasi-periodic echoes.
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Multi-point Measurements of Relativistic Electrons in the Magnetosphere
NASA Astrophysics Data System (ADS)
Li, X.; Selesnick, R.; Baker, D. N.; Blake, J. B.; Schiller, Q.; Blum, L. W.; Zhao, H.; Jaynes, A. N.; Kanekal, S.
2014-12-01
We take an advantage of five different DC electric field measurements in the plasma sheet available from the EFW double probe experiment, EDI electron drift instrument, CODIF and HIA ion spectrometers, and PEACE electron spectrometer on the four Cluster spacecraft. The calibrated observations of the three spectrometers are used to determine the proton and electron velocity moments. The velocity moments can be used to estimate the proton and electron drift velocity and furthermore the DC electric field, assuming that the electron and proton velocity perpendicular to the magnetic field is dominated by the ExB drift motion. Naturally when ions and electrons do not perform a proper drift motion, which can happen in the plasma sheet, the estimated DC electric field from ion and electron motion is not correct. However, surprisingly often the DC electric fields estimated from electron and ion motions are identical suggesting that this field is a real DC electric field around the measurement point. As the measurement techniques are so different, it is quite plausible that when two different measurements yield the same DC electric field, it is the correct field. All five measurements of the DC electric field are usually not simultaneously available, especially on Cluster 2 where CODIF and HIA are not operational, or on Cluster 4 where EDI is off. In this presentation we investigate DC electric field in various transient plasma sheet events such as dipolarization events and BBF's and how the five measurements agree or disagree. There are plenty of important issues that are considered, e.g., (1) what kind of DC electric fields exist in such events and what are their spatial scales, (2) do electrons and ions perform ExB drift motions in these events, and (3) how well the instruments have been calibrated.
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Electrical Behavior of Copper Mine Tailings During EKR with Modified Electric Fields.
Rojo, Adrian; Hansen, Henrik K; Monárdez, Omara; Jorquera, Carlos; Santis, Paulina; Inostroza, Paula
2017-03-01
Electro-kinetic remediation (EKR) with sinusoidal electric field obtained simultaneously with DC/AC voltage reduce the polarization of the EKR with DC voltage. The DC voltage value defines the presence of a periodic polarity reversal of the cell and the electrical charge for electro-kinetic transport. In this case, the AC frequency favors the breaking of polarization conditions resulting from the EKR with DC voltage. However, with high frequencies a negative effect occurs where the tailings behave as a filter circuit, discriminating frequencies of an electric signal. The goal of this work is to analyse the electrical behaviour of tailings in EKR experiments. The conditions selected were: DC/AC voltages: 10/15 and 20/25 V (peak values), and AC voltage frequencies 50-2000 Hz. When the AC frequency reaches 2000 Hz, the copper removal tends to zero, indicating that the tailing behaves as a high-pass filter in which the DC voltage was filtered out.
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In vitro effects of direct current electric fields on adipose-derived stromal cells.
Hammerick, Kyle E; Longaker, Michael T; Prinz, Fritz B
2010-06-18
Endogenous electric fields play an important role in embryogenesis, regeneration, and wound repair and previous studies have shown that many populations of cells, leukocytes, fibroblasts, epithelial cells, and endothelial cells, exhibit directed migration in response to electric fields. As regenerative therapies continue to explore ways to control mesenchymal progenitor cells to recreate desirable tissues, it is increasingly necessary to characterize the vast nature of biological responses imposed by physical phenomena. Murine adipose-derived stromal cells (mASCs) migrated toward the cathode in direct current (DC) fields of physiologic strength and show a dose dependence of migration rate to stronger fields. Electric fields also caused mASCs to orient perpendicularly to the field vector and elicited a transient increase in cytosolic calcium. Additionally, their galvanotactic response appears to share classic chemotactic signaling pathways that are involved in the migration of other cell types. Galvanotaxis is one predominant result of electric fields on mASCs and it may be exploited to engineer adult stem cell concentrations and locations within implanted grafts or toward sites of wound repair. Copyright (c) 2010 Elsevier Inc. All rights reserved.
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Analysis of Electric Vehicle DC High Current Conversion Technology
NASA Astrophysics Data System (ADS)
Yang, Jing; Bai, Jing-fen; Lin, Fan-tao; Lu, Da
2017-05-01
Based on the background of electric vehicles, it is elaborated the necessity about electric energy accurate metering of electric vehicle power batteries, and it is analyzed about the charging and discharging characteristics of power batteries. It is needed a DC large current converter to realize accurate calibration of power batteries electric energy metering. Several kinds of measuring methods are analyzed based on shunts and magnetic induction principle in detail. It is put forward power batteries charge and discharge calibration system principle, and it is simulated and analyzed ripple waves containing rate and harmonic waves containing rate of power batteries AC side and DC side. It is put forward suitable DC large current measurement methods of power batteries by comparing different measurement principles and it is looked forward the DC large current measurement techniques.
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NASA Astrophysics Data System (ADS)
Fachrurrozi, Muhammad; Saparudin; Erwin
2017-04-01
Real-time Monitoring and early detection system which measures the quality standard of waste in Musi River, Palembang, Indonesia is a system for determining air and water pollution level. This system was designed in order to create an integrated monitoring system and provide real time information that can be read. It is designed to measure acidity and water turbidity polluted by industrial waste, as well as to show and provide conditional data integrated in one system. This system consists of inputting and processing the data, and giving output based on processed data. Turbidity, substances, and pH sensor is used as a detector that produce analog electrical direct current voltage (DC). Early detection system works by determining the value of the ammonia threshold, acidity, and turbidity level of water in Musi River. The results is then presented based on the level group pollution by the Support Vector Machine classification method.
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Isolated step-down DC -DC converter for electric vehicles
NASA Astrophysics Data System (ADS)
Kukovinets, O. V.; Sidorov, K. M.; Yutt, V. E.
2018-02-01
Modern motor-vehicle industrial sector is moving rapidly now towards the electricity-driving cars production, improving their range and efficiency of components, and in particular the step-down DC/DC converter to supply the onboard circuit 12/24V of electric vehicle from the high-voltage battery. The purpose of this article - to identify the best circuitry topology to design an advanced step-down DC/DC converters with the smallest mass, volume, highest efficiency and power. And this will have a positive effect on driving distance of electric vehicle (EV). On the basis of computational research of existing and implemented circuit topologies of step-down DC/DC converters (serial resonant converter, full bridge with phase-shifting converter, LLC resonant converter) a comprehensive analysis was carried out on the following characteristics: specific volume, specific weight, power, efficiency. The data obtained was the basis for the best technical option - LLC resonant converter. The results can serve as a guide material in the process of components design of the traction equipment for electric vehicles, providing for the best technical solutions in the design and manufacturing of converting equipment, self-contained power supply systems and advanced driver assistance systems.
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NASA Astrophysics Data System (ADS)
Ebisawa, Yoshihito; Yamada, Shin; Mori, Shigekazu; Ikeda, Masami
This paper describes breakdown characteristics of an oil-pressboard insulation system to a superposition voltage of AC and DC voltages. Although AC electric field is decided by the ratio of the relative permittivity of a pressboard and insulating oil, DC electric field is decided by ratio α of volume resistivities. From the measurement in this study, 13—78 and 1.8—5.7 are obtained as the volume resistivity ratios α at temperature of 30°C and 80°C, respectively. The breakdown voltages against AC, DC, and those superposition voltages are surveyed to insulation models. In normal temperature, the breakdown voltage to the superposition voltage of AC and DC is determined by AC electric field applied to the oil duct. Since the α becomes as low as 2-3 at temperature of 80°C, AC and DC voltages almost equally contribute to the electric field of the oil duct as a result. That is, it became clear that superposed DC voltage boosts the electric field across oil ducts at operating high temperature.
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Multipactor susceptibility on a dielectric with a bias dc electric field and a background gas
DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhang Peng; Lau, Y. Y.; Franzi, Matthew
2011-05-15
We use Monte Carlo simulations and analytical calculations to derive the condition for the onset of multipactor discharge on a dielectric surface at various combinations of the bias dc electric field, rf electric field, and background pressures of noble gases, such as Argon. It is found that the presence of a tangential bias dc electric field on the dielectric surface lowers the magnitude of rf electric field threshold to initiate multipactor, therefore plausibly offering robust protection against high power microwaves. The presence of low pressure gases may lead to a lower multipactor saturation level, however. The combined effects of tangentialmore » dc electric field and external gases on multipactor susceptibility are presented.« less
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Moazami, Hamid Reza; Hosseiny Davarani, Saied Saeed; Mohammadi, Jamil; Nojavan, Saeed; Abrari, Masoud
2015-09-03
The distribution of electric field vectors was first calculated for electromembrane extraction (EME) systems in classical and cylindrical electrode geometries. The results showed that supported liquid membrane (SLM) has a general field amplifying effect due to its lower dielectric constant in comparison with aqueous donor/acceptor solutions. The calculated norms of the electric field vector showed that a DC voltage of 50 V can create huge electric field strengths up to 64 kV m(-1) and 111 kV m(-1) in classical and cylindrical geometries respectively. In both cases, the electric field strength reached its peak value on the inner wall of the SLM. In the case of classical geometry, the field strength was a function of the polar position of the SLM whereas the field strength in cylindrical geometry was angularly uniform. In order to investigate the effect of the electrode geometry on the performance of real EME systems, the analysis was carried out in three different geometries including classical, helical and cylindrical arrangements using naproxen and sodium diclofenac as the model analytes. Despite higher field strength and extended cross sectional area, the helical and cylindrical geometries gave lower recoveries with respect to the classical EME. The observed decline of the signal was proved to be against the relations governing migration and diffusion processes, which means that a third driving force is involved in EME. The third driving force is the interaction between the radially inhomogeneous electric field and the analyte in its neutral form. Copyright © 2015 Elsevier B.V. All rights reserved.
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UDE-based control of variable-speed wind turbine systems
NASA Astrophysics Data System (ADS)
Ren, Beibei; Wang, Yeqin; Zhong, Qing-Chang
2017-01-01
In this paper, the control of a PMSG (permanent magnet synchronous generator)-based variable-speed wind turbine system with a back-to-back converter is considered. The uncertainty and disturbance estimator (UDE)-based control approach is applied to the regulation of the DC-link voltage and the control of the RSC (rotor-side converter) and the GSC (grid-side converter). For the rotor-side controller, the UDE-based vector control is developed for the RSC with PMSG control to facilitate the application of the MPPT (maximum power point tracking) algorithm for the maximum wind energy capture. For the grid-side controller, the UDE-based vector control is developed to control the GSC with the power reference generated by a UDE-based DC-link voltage controller. Compared with the conventional vector control, the UDE-based vector control can achieve reliable current decoupling control with fast response. Moreover, the UDE-based DC-link voltage regulation can achieve stable DC-link voltage under model uncertainties and external disturbances, e.g. wind speed variations. The effectiveness of the proposed UDE-based control approach is demonstrated through extensive simulation studies in the presence of coupled dynamics, model uncertainties and external disturbances under varying wind speeds. The UDE-based control is able to generate more energy, e.g. by 5% for the wind profile tested.
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Space Charge Modulated Electrical Breakdown
Li, Shengtao; Zhu, Yuanwei; Min, Daomin; Chen, George
2016-01-01
Electrical breakdown is one of the most important physical phenomena in electrical and electronic engineering. Since the early 20th century, many theories and models of electrical breakdown have been proposed, but the origin of one key issue, that the explanation for dc breakdown strength being twice or higher than ac breakdown strength in insulating materials, remains unclear. Here, by employing a bipolar charge transport model, we investigate the space charge dynamics in both dc and ac breakdown processes. We demonstrate the differences in charge accumulations under both dc and ac stresses and estimate the breakdown strength, which is modulated by the electric field distortion induced by space charge. It is concluded that dc breakdown initializes in the bulk whereas ac breakdown initializes in the vicinity of the sample-electrode interface. Compared with dc breakdown, the lower breakdown strength under ac stress and the decreasing breakdown strength with an increase in applied frequency, are both attributed to the electric field distortion induced by space charges located in the vicinity of the electrodes. PMID:27599577
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DC breakdown characteristics of silicone polymer composites for HVDC insulator applications
NASA Astrophysics Data System (ADS)
Han, Byung-Jo; Seo, In-Jin; Seong, Jae-Kyu; Hwang, Young-Ho; Yang, Hai-Won
2015-11-01
Critical components for HVDC transmission systems are polymer insulators, which have stricter requirements that are more difficult to achieve compared to those of HVAC insulators. In this study, we investigated the optimal design of HVDC polymer insulators by using a DC electric field analysis and experiments. The physical properties of the polymer specimens were analyzed to develop an optimal HVDC polymer material, and four polymer specimens were prepared for DC breakdown experiments. Single and reverse polarity breakdown tests were conducted to analyze the effect of temperature on the breakdown strength of the polymer. In addition, electric fields were analyzed via simulations, in which a small-scale polymer insulator model was applied to prevent dielectric breakdown due to electric field concentration, with four DC operating conditions taken into consideration. The experimental results show that the electrical breakdown strength and the electric field distribution exhibit significant differences in relation to different DC polarity transition procedures.
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Converter topologies for common mode voltage reduction
DOE Office of Scientific and Technical Information (OSTI.GOV)
Rodriguez, Fernando
An inverter includes a three-winding transformer, a DC-AC inverter electrically coupled to the first winding of the transformer, a cycloconverter electrically coupled to the second winding of the transformer, and an active filter electrically coupled to the third winding of the transformer. The DC-AC inverter is adapted to convert the input DC waveform to an AC waveform delivered to the transformer at the first winding. The cycloconverter is adapted to convert an AC waveform received at the second winding of the transformer to the output AC waveform having a grid frequency of the AC grid. The active filter is adaptedmore » to sink and source power with one or more energy storage devices based on a mismatch in power between the DC source and the AC grid. At least two of the DC-AC inverter, the cycloconverter, or the active filter are electrically coupled via a common reference electrical interconnect.« less
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Roddee, J; Kobori, Y; Yorozuya, H; Hanboonsong, Y
2017-06-01
The leafhopper Matsumuratettix hiroglyphicus (Matsumura) (Hemiptera: Cicadellidae) is an important vector of phytoplasma causing white leaf disease in sugarcane. Thus, the aim of our study was to understand and describe the stylet-probing activities of this vector while feeding on sugarcane plants, by using direct current (DC) electrical penetration graph (EPG) monitoring. The EPG signals were classified into six distinct waveforms, according to amplitude, frequency, voltage level, and electrical origin of the observed traces during stylet penetration into the host plant tissues (probing). These six EPG waveforms of probing behavior comprise no stylet penetration (NP); stylet pathway through epidermis, mesophyll, and parenchymal cells (waveform A); contact at the bundle sheath layer (waveform B); salivation into phloem sieve elements (waveform C); phloem sap ingestion (waveform D); and short ingestion time of xylem sap (waveform E). The above waveform patterns were correlated with histological data of salivary sheath termini in plant tissue generated from insect stylet tips. The key findings of this study were that M. hiroglyphicus ingests the phloem sap at a relatively higher rate and for longer duration from any other cell type, suggesting that M. hiroglyphicus is mainly a phloem-feeder. Quantitative comparison of probing behavior revealed that females typically probe more frequently and longer in the phloem than males. Thus, females may acquire and inoculate greater amounts of phytoplasma than males, enhancing the efficiency of phytoplasma transmission and potentially exacerbating disease spreading. Overall, our study provides basic information on the probing behavior and transmission mechanism of M. hiroglyphicus. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.
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Influence of bias electric field on elastic waves propagation in piezoelectric layered structures.
Burkov, S I; Zolotova, O P; Sorokin, B P
2013-08-01
Theoretical and computer investigations of acoustic wave propagation in piezoelectric layered structures, subjected to the dc electric field influence have been fulfilled. Analysis of the dispersive parameters of elastic waves propagation in the BGO/fused silica and fused silica/LiNbO3 piezoelectric layered structures for a number of variants of dc electric field application has been executed. Transformation of bulk acoustic wave into SAW type mode under the dc electric field influence has been found. Possibility to control the permission or prohibition of the wave propagation by the dc electric field application and the appropriate choice of the layer and substrate materials has been discussed. Copyright © 2013 Elsevier B.V. All rights reserved.
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Worgall, Stefan; Busch, Annette; Rivara, Michael; Bonnyay, David; Leopold, Philip L.; Merritt, Robert; Hackett, Neil R.; Rovelink, Peter W.; Bruder, Joseph T.; Wickham, Thomas J.; Kovesdi, Imi; Crystal, Ronald G.
2004-01-01
Adenovirus (Ad) gene transfer vectors can be used to transfer and express antigens and function as strong adjuvants and thus are useful platforms for the development of genetic vaccines. Based on the hypothesis that Ad vectors with enhanced infectibility of dendritic cells (DC) may be able to evoke enhanced immune responses against antigens encoded by the vector in vivo, the present study analyzes the vaccine potential of an Ad vector expressing β-galactosidase as a model antigen and genetically modified with RGD on the fiber knob [AdZ.F(RGD)] to more selectively infect DC and consequently enhance immunity against the β-galactosidase antigen. Infection of murine DC in vitro with AdZ.F(RGD) showed an eightfold-increased transgene expression following infection compared to AdZ (also expressing β-galactosidase, but with a wild-type capsid). Binding, cellular uptake, and trafficking in DC were also increased with AdZ.F(RGD) compared to AdZ. To determine whether AdZ.F(RGD) could evoke enhanced immune responses to β-galactosidase in vivo, C57BL/6 mice were immunized with AdZ.F(RGD) or AdZ subcutaneously via the footpad. Humoral responses with both vectors were comparable, with similar anti-β-galactosidase antibody levels following vector administration. However, cellular responses to β-galactosidase were significantly enhanced, with the frequency of CD4+ as well as the CD8+ β-galactosidase-specific gamma interferon response in cells isolated from the draining lymph nodes increased following immunization with AdZ.F(RGD) compared to Ad.Z (P < 0.01). Importantly, this enhanced cellular immune response of the AdZ.F(RGD) vector was sufficient to evoke enhanced inhibition of the growth of preexisting tumors expressing β-galactosidase: BALB/c mice implanted with the CT26 syngeneic β-galactosidase-expressing colon carcinoma cell line and subsequently immunized with AdZ.F(RGD) showed decreased tumor growth and improved survival compared to mice immunized with AdZ. These data demonstrate that addition of an RGD motif to the Ad fiber knob increases the infectibility of DC and leads to enhanced cellular immune responses to the Ad-transferred transgene, suggesting that the RGD capsid modification may be useful in developing Ad-based vaccines. PMID:14963160
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A wide bandwidth electrostatic field sensor for lightning research
NASA Technical Reports Server (NTRS)
Zaepfel, K. P.
1986-01-01
Data obtained from UHF Radar observation of direct-lightning strikes to the NASA F-106B airplane have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero volts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The new system was implemented with four shutter-type field mills located at strategic points on the airplane. The bandwidth of the new system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 Hz to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite-difference time-domain electromagnetic computer code.
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A wide bandwidth electrostatic field sensor for lightning research
NASA Technical Reports Server (NTRS)
Zaepfel, Klaus P.
1989-01-01
Data obtained from UHF radar observation of direct-lightning strikes to the NASA F-106B aircraft have indicated that most of the 690 strikes acquired during direct-strike lightning tests were triggered by the aircraft. As an aid in understanding the triggered lightning process, a wide bandwidth electric field measuring system was designed for the F-106B by implementing a clamped-detection signal processing concept originated at the Air Force Cambridge Research Lab in 1953. The detection scheme combines the signals from complementary stator pairs clamped to zero bolts at the exact moment when each stator pair is maximally shielded by the rotor, a process that restores the dc level lost by the charge amplifier. The system was implemented with four shutter-type field mills located at strategic points on the aircraft. The bandwidth of the system was determined in the laboratory to be from dc to over 100 Hz, whereas past designs had upper limits of 10 to 100 Hz. To obtain the undisturbed electric field vector and total aircraft charge, the airborne field mill system is calibrated by using techniques involving results from ground and flight calibrations of the F-106B, laboratory tests of a metallized model, and a finite difference time-domain electromagnetic computer code.
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NASA Astrophysics Data System (ADS)
Xu, Yonggang; Zhang, Deyuan; Cai, Jun; Yuan, Liming; Zhang, Wenqiang
2013-02-01
Silicone rubber composites filled with carbonyl iron particles (CIPs) and graphite platelet (GP) were prepared using non-coating or coating processes. The complex permittivity and permeability of the composites were measured using a vector network analyzer in the frequency range of 1-18 GHz and dc electric conductivity was measured by the standard four-point contact method. The results showed that CIPs/GP composites fabricated in the coating process had the highest permittivity and permeability due to the particle orientation and interactions between the two absorbents. The coating process resulted in a decreased effective eccentricity of the absorbents, and the dc conductivity increased according to Neelakanta's equations. The reflection loss (RL) value showed that the composites had an excellent absorbing property in the L-band, minimum -11.85 dB at 1.5 mm and -15.02 dB at 2 mm. Thus, GP could be an effective additive in preparing thin absorbing composites in the L-band.
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The influence of electric field and confinement on cell motility.
Huang, Yu-Ja; Samorajski, Justin; Kreimer, Rachel; Searson, Peter C
2013-01-01
The ability of cells to sense and respond to endogenous electric fields is important in processes such as wound healing, development, and nerve regeneration. In cell culture, many epithelial and endothelial cell types respond to an electric field of magnitude similar to endogenous electric fields by moving preferentially either parallel or antiparallel to the field vector, a process known as galvanotaxis. Here we report on the influence of dc electric field and confinement on the motility of fibroblast cells using a chip-based platform. From analysis of cell paths we show that the influence of electric field on motility is much more complex than simply imposing a directional bias towards the cathode or anode. The cell velocity, directedness, as well as the parallel and perpendicular components of the segments along the cell path are dependent on the magnitude of the electric field. Forces in the directions perpendicular and parallel to the electric field are in competition with one another in a voltage-dependent manner, which ultimately govern the trajectories of the cells in the presence of an electric field. To further investigate the effects of cell reorientation in the presence of a field, cells are confined within microchannels to physically prohibit the alignment seen in 2D environment. Interestingly, we found that confinement results in an increase in cell velocity both in the absence and presence of an electric field compared to migration in 2D.
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Integration of regenerative shock absorber into vehicle electric system
NASA Astrophysics Data System (ADS)
Zhang, Chongxiao; Li, Peng; Xing, Shaoxu; Kim, Junyoung; Yu, Liangyao; Zuo, Lei
2014-03-01
Regenerative/Energy harvesting shock absorbers have a great potential to increase fuel efficiency and provide suspension damping simultaneously. In recent years there's intensive work on this topic, but most researches focus on electricity extraction from vibration and harvesting efficiency improvement. The integration of electricity generated from regenerative shock absorbers into vehicle electric system, which is very important to realize the fuel efficiency benefit, has not been investigated. This paper is to study and demonstrate the integration of regenerative shock absorber with vehicle alternator, battery and in-vehicle electrical load together. In the presented system, the shock absorber is excited by a shaker and it converts kinetic energy into electricity. The harvested electricity flows into a DC/DC converter which realizes two functions: controlling the shock absorber's damping and regulating the output voltage. The damping is tuned by controlling shock absorber's output current, which is also the input current of DC/DC converter. By adjusting the duty cycles of switches in the converter, its input impedance together with input current can be adjusted according to dynamic damping requirements. An automotive lead-acid battery is charged by the DC/DC converter's output. To simulate the working condition of combustion engine, an AC motor is used to drive a truck alternator, which also charges the battery. Power resistors are used as battery's electrical load to simulate in-vehicle electrical devices. Experimental results show that the proposed integration strategy can effectively utilize the harvested electricity and power consumption of the AC motor is decreased accordingly. This proves the combustion engine's load reduction and fuel efficiency improvement.
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Kinetic theory for electrostatic waves due to transverse velocity shears
NASA Technical Reports Server (NTRS)
Ganguli, G.; Lee, Y. C.; Palmadesso, P. J.
1988-01-01
A kinetic theory in the form of an integral equation is provided to study the electrostatic oscillations in a collisionless plasma immersed in a uniform magnetic field and a nonuniform transverse electric field. In the low temperature limit the dispersion differential equation is recovered for the transverse Kelvin-Helmholtz modes for arbitrary values of K parallel, where K parallel is the component of the wave vector in the direction of the external magnetic field assumed in the z direction. For higher temperatures the ion-cyclotron-like modes described earlier in the literature by Ganguli, Lee and Plamadesso are recovered. In this article, the integral equation is reduced to a second-order differential equation and a study is made of the kinetic Kelvin-Helmholtz and ion-cyclotron-like modes that constitute the two branches of oscillation in a magnetized plasma including a transverse inhomogeneous dc electric field.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Mihelic, Andrej; Zitnik, Matjaz
2007-06-15
We study the Stark effect on doubly excited states of the helium atom below N=2. We present the ab initio photoionization and total inelastic photon scattering cross sections calculated with the method of complex scaling for field strengths F{<=}100 kV/cm. The calculations are compared to the measurements of the ion [Phys. Rev. Lett. 90, 133002 (2003)] and vacuum ultraviolet fluorescence yields [Phys. Rev. Lett. 96, 093001 (2006)]. For the case of photoionization and for incident photons with polarization vector P parallel to the electric field F, we confirm the propensity rule proposed by Tong and Lin [Phys. Rev. Lett. 92,more » 223003 (2004)]. Furthermore, the rule is also shown to apply for F perpendicular P and for the case of the inelastic scattering in both experimental geometries.« less
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She, Xu; Chokhawala, Rahul Shantilal; Bray, James William; Sommerer, Timothy John; Zhou, Rui; Zhang, Di
2017-08-29
A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to "switch on" one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and "switch off" the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.
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Sensor probes and phantoms for advanced transcranial magnetic stimulation system developments
NASA Astrophysics Data System (ADS)
Meng, Qinglei; Patel, Prashil; Trivedi, Sudhir; Du, Xiaoming; Hong, Elliot; Choa, Fow-Sen
2015-05-01
Transcranial magnetic stimulation (TMS) has become one of the most widely used noninvasive method for brain tissue stimulation and has been used as a treatment tool for various neurological and psychiatric disorders including migraine, stroke, Parkinson's disease, dystonia, tinnitus and depression. In the process of developing advanced TMS deep brain stimulation tools, we need first to develop field measurement devices like sensory probes and brain phantoms, which can be used to calibrate the TMS systems. Currently there are commercially available DC magnetic or electric filed measurement sensors, but there is no instrument to measure transient fields. In our study, we used a commercial figure-8 shaped TMS coil to generate transient magnetic field and followed induced field and current. The coil was driven by power amplified signal from a pulse generator with tunable pulse rate, amplitude, and duration. In order to obtain a 3D plot of induced vector electric field, many types of probes were designed to detect single component of electric-field vectors along x, y and z axis in the space around TMS coil. We found that resistor probes has an optimized signal-to-noise ratio (SNR) near 3k ohm but it signal output is too weak compared with other techniques. We also found that inductor probes can have very high output for Curl E measurement, but it is not the E-field distribution we are interested in. Probes with electrical wire wrapped around iron coil can directly measure induced E-field with high sensitivity, which matched computer simulation results.
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NASA Technical Reports Server (NTRS)
Edie, P. C.
1981-01-01
Both straight and chopped dc motor performance data for a General Electric 5BY436A1 motor with a General Electric EV-1 controller is presented in tabular and graphical formats. Effects of motor temperature and operating voltage are also shown. The maximum motor efficiency is approximately 85% at low operating temperatures in the straight dc mode. Chopper efficiency can be assumed to be 95% under all operating conditions. For equal speeds, the motor operated in the chopped mode develops slightly more torque and draws more current than it does in the straight mode.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Wicks, F.
1998-07-01
The need to produce electricity either more fuel efficiently or without need for consuming fuel is well recognized. Fuel cells are typically suggested for higher efficiency and photovoltaics can produce electricity directly from the sun. However, both of these devices produce direct current which is not compatible with the existing ac power system. The typical options of installing AC to DC inverters and the dedication of this DC generation to DC loads and storage are costly and inefficient. Thus, the author suggests it would be better in terms of energy conservation and public policy to convert end use service tomore » DC for direct compatibility with this DC generation, as a first step toward conversion to a new and better type of electric power system that can be described as a solid state power electronics based multiple voltage DC power system.« less
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Power Strategy in DC/DC Converters to Increase Efficiency of Electrical Stimulators.
Aqueveque, Pablo; Acuña, Vicente; Saavedra, Francisco; Debelle, Adrien; Lonys, Laurent; Julémont, Nicolas; Huberland, François; Godfraind, Carmen; Nonclercq, Antoine
2016-06-13
Power efficiency is critical for electrical stimulators. Battery life of wearable stimulators and wireless power transmission in implanted systems are common limiting factors. Boost DC/DC converters are typically needed to increase the supply voltage of the output stage. Traditionally, boost DC/DC converters are used with fast control to regulate the supply voltage of the output. However, since stimulators are acting as current sources, such voltage regulation is not needed. Banking on this, this paper presents a DC/DC conversion strategy aiming to increase power efficiency. It compares, in terms of efficiency, the traditional use of boost converters to two alternatives that could be implemented in future hardware designs.
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Photovoltaic system with improved DC connections and method of making same
DOE Office of Scientific and Technical Information (OSTI.GOV)
Cioffi, Philip Michael; Todorovic, Maja Harfman; Herzog, Michael Scott
A micro-inverter assembly includes a housing having an opening formed in a bottom surface thereof, and a direct current (DC)-to-alternating current (AC) micro-inverter disposed within the housing at a position adjacent to the opening. The micro-inverter assembly further includes a micro-inverter DC connector electrically coupled to the DC-to-AC micro-inverter and positioned within the opening of the housing, the micro-inverter DC connector having a plurality of exposed electrical contacts.
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Federal Register 2010, 2011, 2012, 2013, 2014
2013-04-30
.../diminished. There are no design changes associated with this TS amendment. The DC power system/batteries will... changes restructure the Technical Specifications (TS) for the direct current (DC) electrical power system... battery and battery charger operability requirements. The DC electrical power system, including associated...
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Synthetic Space Vector Modulation
2013-06-01
especially batteries without fancy controls. Inherently, DC machine commutation is environmentally sensitive and maintenance intensive at well as...reliable DC power supplies especially batteries without fancy controls. Inherently, DC machine commutation is environmentally sensitive and maintenance...Drives and Energy Systems, New Delhi, India , 20-23 December, 2010. [12] PIC18F2331/2431/4331/4431 datasheet DS39616B, Microchip Technology Inc
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Pupils' Representations of Electric Current before, during and after Instruction on DC Circuits.
ERIC Educational Resources Information Center
Psillos, D.; And Others
1987-01-01
Reported are compulsory education pupils' representations of electric current in a constructivist approach to introducing direct current (DC) circuits. Suggests that the pupils views can be modelled after an energy framework. Makes suggestions about the content, the apparatus and the experiments used in teaching DC circuits. (CW)
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Samrat, Nahidul Hoque; Ahmad, Norhafizan; Choudhury, Imtiaz Ahmed; Taha, Zahari
2015-01-01
Energy is one of the most important factors in the socioeconomic development of a country. In a developing country like Malaysia, the development of islands is mostly related to the availability of electric power. Power generated by renewable energy sources has recently become one of the most promising solutions for the electrification of islands and remote rural areas. But high dependency on weather conditions and the unpredictable nature of these renewable energy sources are the main drawbacks. To overcome this weakness, different green energy sources and power electronic converters need to be integrated with each other. This study presents a battery storage hybrid standalone photovoltaic-wind energy power supply system. In the proposed standalone hybrid system, a DC-DC buck-boost bidirectional converter controller is used to accumulates the surplus hybrid power in the battery bank and supplies this power to the load during the hybrid power shortage by maintaining the constant dc-link voltage. A three-phase voltage source inverter complex vector control scheme is used to control the load side voltage in terms of the voltage amplitude and frequency. Based on the simulation results obtained from MATLAB/Simulink, it has been found that the overall hybrid framework is capable of working under variable weather and load conditions. PMID:26121032
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Samrat, Nahidul Hoque; Ahmad, Norhafizan; Choudhury, Imtiaz Ahmed; Taha, Zahari
2015-01-01
Energy is one of the most important factors in the socioeconomic development of a country. In a developing country like Malaysia, the development of islands is mostly related to the availability of electric power. Power generated by renewable energy sources has recently become one of the most promising solutions for the electrification of islands and remote rural areas. But high dependency on weather conditions and the unpredictable nature of these renewable energy sources are the main drawbacks. To overcome this weakness, different green energy sources and power electronic converters need to be integrated with each other. This study presents a battery storage hybrid standalone photovoltaic-wind energy power supply system. In the proposed standalone hybrid system, a DC-DC buck-boost bidirectional converter controller is used to accumulates the surplus hybrid power in the battery bank and supplies this power to the load during the hybrid power shortage by maintaining the constant dc-link voltage. A three-phase voltage source inverter complex vector control scheme is used to control the load side voltage in terms of the voltage amplitude and frequency. Based on the simulation results obtained from MATLAB/Simulink, it has been found that the overall hybrid framework is capable of working under variable weather and load conditions.
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Solar Photovoltaic DC Systems: Basics and Safety: Preprint
DOE Office of Scientific and Technical Information (OSTI.GOV)
McNutt, Peter F; Sekulic, William R; Dreifuerst, Gary
Solar Photovoltaic (PV) systems are common and growing with 42.4 GW installed capacity in U.S. (almost 15 GW added in 2016). This paper will help electrical workers, and emergency responders understand the basic operating principles and hazards of PV DC arrays. We briefly discuss the following aspects of solar photovoltaic (PV) DC systems: the effects of solar radiation and temperature on output power; PV module testing standards; common system configurations; a simple PV array sizing example; NEC guidelines and other safety features; DC array commissioning, periodic maintenance and testing; arc-flash hazard potential; how electrical workers and emergency responders can andmore » do work safely around PV arrays; do moonlight and artificial lighting pose a real danger; typical safe operating procedures; and other potential DC-system hazards to be aware of. We also present some statistics on PV DC array electrical incidents and injuries. Safe PV array operation is possible with a good understanding of PV DC arrays basics and having good safe operating procedures in place.« less
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NASA Technical Reports Server (NTRS)
Ludwig, Kimberly; Mackin, Michael; Wright, Theodore
1991-01-01
The Ada language software development to perform the electrical system monitoring functions for the NASA Lewis Research Center's Power Management and Distribution (PMAD) DC testbed is described. The results of the effort to implement this monitor are presented. The PMAD DC testbed is a reduced-scale prototype of the electrical power system to be used in the Space Station Freedom. The power is controlled by smart switches known as power control components (or switchgear). The power control components are currently coordinated by five Compaq 382/20e computers connected through an 802.4 local area network. One of these computers is designated as the control node with the other four acting as subsidiary controllers. The subsidiary controllers are connected to the power control components with a Mil-Std-1553 network. An operator interface is supplied by adding a sixth computer. The power system monitor algorithm is comprised of several functions including: periodic data acquisition, data smoothing, system performance analysis, and status reporting. Data is collected from the switchgear sensors every 100 milliseconds, then passed through a 2 Hz digital filter. System performance analysis includes power interruption and overcurrent detection. The reporting mechanism notifies an operator of any abnormalities in the system. Once per second, the system monitor provides data to the control node for further processing, such as state estimation. The system monitor required a hardware time interrupt to activate the data acquisition function. The execution time of the code was optimized using an assembly language routine. The routine allows direct vectoring of the processor to Ada language procedures that perform periodic control activities. A summary of the advantages and side effects of this technique are discussed.
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Standardized Curriculum for Electricity/Electronics.
ERIC Educational Resources Information Center
Mississippi State Dept. of Education, Jackson. Office of Vocational, Technical and Adult Education.
Standardized vocational education course titles and core contents are provided for two courses in Mississippi: electricity/electronics I and II. The first course contains the following units: (1) orientation, safety, and leadership; (2) basic principles of electricity/electronics; (3) direct current (DC) theory; (4) magnetism and DC motors; (5)…
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NASA Technical Reports Server (NTRS)
Schjelderup, H. C.; Cook, C. Q.; Snyder, E.; Henning, B.; Hosford, J.; Gilles, D. L.; Swanstrom, C. W.
1980-01-01
The potential hazard to electrical and electronic devices should there be a release of free carbon fibers due to an aircraft crash and fire was assessed. Exposure and equipment sensitivity data were compiled for a risk analysis. Results are presented in the following areas: DC-9/DC-10 electrical/electronic component characterization; DC-9 and DC-10 fiber transfer functions; potential for transport aircraft equipment exposure to carbon fibers; and equipment vulnerability assessment. Results reflect only a negligible increase in risk for the DC-9 and DC-10 fleets either now or projected to 1993.
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NASA Astrophysics Data System (ADS)
Bauer, Rita A.; Kelemen, Lóránd; Nakano, Masami; Totsuka, Atsushi; Zrínyi, Miklós
2015-10-01
We have presented the first direct observation of electric field induced rotation of epoxy based polymer rotors. Polymer disks, hollow cylinders and gears were prepared in few micrometer dimensions as rotors. Electrorotation of these sub-millimeter sized tools was studied under uniform dc electric field. The effects of shape, size and thickness were investigated. The novel epoxy based micro devices show intensive spinning in a uniform dc electric field. The rotational speed of micron-sized polymer rotors can be conveniently tuned in a wide range (between 300 and 3000 rpm) by the electric field intensity, opening new perspectives for their use in several MEMS applications.
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Wang, Hsiang-Yu; Lu, Chang
2008-06-15
Electroporation is an efficient method of introducing foreign impermeant molecules such as drugs and genes into cells. Conventional electroporation has been based on the application of short electrical pulses (electropulsation). Electropulsation requires specialized equipment and cannot be integrated easily with techniques such as electrophoresis which is based on constant voltage. Here we demonstrate the delivery of small molecules and genes into cells, using a microfluidic electroporation technique based on constant direct current (DC) voltage that we developed earlier. We demonstrate the delivery of two molecules into Chinese hamster ovary (CHO-K1) cells: a membrane impermeable nucleic acid dye (SYTOX Green) and a plasmid vector carrying the gene for green fluorescent protein (pEGFP-C1). Our devices can exert field variations to flowing cells that are analogous to the application of single or multiple pulses by having different geometries. We investigate the effects of the electrical parameters and different geometries of the device on the transfection efficiency and cell viability. Our technique provides a simple solution to electroporation-based drug and gene delivery by eliminating the need for a pulse generator. We envision that these simple microscale electroporation devices will have the potential to work in parallel on a microchip platform and such technology will allow high-throughput functional screening of drugs and genes. (c) 2008 Wiley Periodicals, Inc.
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In vitro and in vivo comparisons of constant resistance AC iontophoresis and DC iontophoresis.
Li, S Kevin; Higuchi, William I; Zhu, Honggang; Kern, Steven E; Miller, David J; Hastings, Matthew S
2003-09-04
A previous in vitro constant electrical resistance alternating current (AC) iontophoresis study with human epidermal membrane (HEM) and a model neutral permeant has shown less inter- and intra-sample variability in iontophoretic transport relative to conventional constant direct current (DC) iontophoresis. The objectives of the present study were to address the following questions. (1) Can the skin electrical resistance be maintained at a constant level by AC in humans in vivo? (2) Are the in vitro data with HEM representative of those in vivo? (3) Does constant skin resistance AC iontophoresis have less inter- and intra-sample variability than conventional constant current DC iontophoresis in vivo? (4) What are the electrical and the barrier properties of skin during iontophoresis in vivo? In the present study, in vitro HEM experiments were carried out with the constant resistance AC and the conventional constant current DC methods using mannitol and glucose as the neutral model permeants. In vivo human experiments were performed using glucose as the permeant with a constant skin resistance AC only protocol and two conventional constant current DC methods (continuous constant current DC and constant current DC with its polarity alternated every 10 min with a 3:7 on:off duty cycle). Constant current DC iontophoresis was conducted with commercial constant current DC devices, and constant resistance AC iontophoresis was carried out by reducing and maintaining the skin resistance at a constant target value with AC supplied from a function generator. This study shows that (1) skin electrical resistance can be maintained at a constant level during AC iontophoresis in vivo; (2) HEM in vitro and human skin in vivo demonstrate similar electrical and barrier properties, and these properties are consistent with our previous findings; (3) there is general qualitative and semi-quantitative agreement between the HEM data in vitro and human skin data in vivo; and (4) constant skin resistance AC iontophoresis generally provides less inter- and intra-subject variability than conventional constant current DC.
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EMTP based stability analysis of space station electric power system in a test bed environment
NASA Technical Reports Server (NTRS)
Dravid, Narayan V.; Kacpura, Thomas J.; Oconnor, Andrew M.
1992-01-01
The Space Station Freedom Electric Power System (EPS) will convert solar energy into electric energy and distribute the same using an 'all dc', Power Management and Distribution (PMAD) System. Power conditioning devices (dc to dc converters) are needed to interconnect parts of this system operating at different nominal voltage levels. Operation of such devices could generate under damped oscillations (instability) under certain conditions. Criteria for instability are examined and verified for a single device. Suggested extension of the criteria to a system operation is examined by using the EMTP model of the PMAD DC test bed. Wherever possible, data from the test bed is compared with the modeling results.
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EMTP based stability analysis of Space Station Electric Power System in a test bed environment
NASA Technical Reports Server (NTRS)
Dravid, Narayan V.; Kacpura, Thomas J.; O'Connor, Andrew M.
1992-01-01
The Space Station Freedom Electric Power System (EPS) will convert solar energy into electric energy and distribute the same using an 'all dc', Power Management and Distribution (PMAD) System. Power conditioning devices (dc to dc converters) are needed to interconnect parts of this system operating at different nominal voltage levels. Operation of such devices could generate under damped oscillations (instability) under certain conditions. Criteria for instability are examined and verified for a single device. Suggested extension of the criteria to a system operation is examined by using the EMTP model of the PMAD dc test bed. Wherever possible, data from the test bed is compared with the modeling results.
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Wang, T; Yang, Z; Dong, P; long, J D; He, X Z; Wang, X; Zhang, K Z; Zhang, L W
2012-06-01
The cold-cathode Penning ion gauge (PIG) type ion source has been used for generation of negative hydrogen (H(-)) ions as the internal ion source of a compact cyclotron. A novel method called electrical shielding box dc beam measurement is described in this paper, and the beam intensity was measured under dc extraction inside an electrical shielding box. The results of the trajectory simulation and dc H(-) beam extraction measurement were presented. The effect of gas flow rate, magnetic field strength, arc current, and extraction voltage were also discussed. In conclusion, the dc H(-) beam current of about 4 mA from the PIG ion source with the puller voltage of 40 kV and arc current of 1.31 A was extrapolated from the measurement at low extraction dc voltages.
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Direct current uninterruptible power supply method and system
Sinha, Gautam
2003-12-02
A method and system are described for providing a direct current (DC) uninterruptible power supply with the method including, for example: continuously supplying fuel to a turbine; converting mechanical power from the turbine into alternating current (AC) electrical power; converting the AC electrical power to DC power within a predetermined voltage level range; supplying the DC power to a load; and maintaining a DC load voltage within the predetermined voltage level range by adjusting the amount of fuel supplied to the turbine.
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An Integrated Onboard Charger and Accessary Power Converter for Plug-in Electric Vehicles
DOE Office of Scientific and Technical Information (OSTI.GOV)
Su, Gui-Jia; Tang, Lixin
2013-01-01
Abstract: In this paper, an integrated onboard battery charger and accessary dc-dc converter for plug-in electric vehicles (PEVs) is presented. The idea is to utilize the already available traction drive inverters and motors of a PEV as the frond converter of the charger circuit and the transformer of the 14 V accessary dc-dc converter to provide galvanic isolation. The topology was verified by modeling and experimental results on a 5 kW charger prototype
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Conductivity of molten sodium chloride in an arbitrarily weak dc electric field.
Delhommelle, Jerome; Cummings, Peter T; Petravic, Janka
2005-09-15
We use nonequilibrium molecular-dynamics (NEMD) simulations to characterize the response of a fluid subjected to an electric field. We focus on the response for very weak fields. Fields accessible by conventional NEMD methods are typically of the order of 10(9) V m(-1), i.e., several orders of magnitude larger than those typically used in experiments. Using the transient time-correlation function, we show how NEMD simulations can be extended to study systems subjected to a realistic dc electric field. We then apply this approach to study the response of molten sodium chloride for a wide range of dc electric fields.
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ERIC Educational Resources Information Center
Leniz, Ane; Zuza, Kristina; Guiasola, Jenaro
2017-01-01
This study examines the causal reasoning that university students use to explain how dc circuits work. We analyze how students use the concepts of electric field and potential difference in their explanatory models of dc circuits, and what kinds of reasoning they use at the macroscopic and microscopic levels in their explanations. This knowledge…
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NASA Astrophysics Data System (ADS)
Alizadeh Sahraei, Abolfazl; Ayati, Moosa; Baniassadi, Majid; Rodrigue, Denis; Baghani, Mostafa; Abdi, Yaser
2018-03-01
This study attempts to comprehensively investigate the effects of multi-walled carbon nanotubes (MWCNTs) on the AC and DC electrical conductivity of epoxy nanocomposites. The samples (0.2, 0.3, and 0.5 wt. % MWCNT) were produced using a combination of ultrason and shear mixing methods. DC measurements were performed by continuous measurement of the current-voltage response and the results were analyzed via a numerical percolation approach, while for the AC behavior, the frequency response was studied by analyzing phase difference and impedance in the 10 Hz to 0.2 MHz frequency range. The results showed that the dielectric parameters, including relative permittivity, impedance phase, and magnitude, present completely different behaviors for the frequency range and MWCNT weight fractions studied. To better understand the nanocomposites electrical behavior, equivalent electric circuits were also built for both DC and AC modes. The DC equivalent networks were developed based on the current-voltage curves, while the AC equivalent circuits were proposed by using an optimization problem according to the impedance magnitude and phase at different frequencies. The obtained equivalent electrical circuits were found to be highly useful tools to understand the physical mechanisms involved in MWCNT filled polymer nanocomposites.
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NASA Astrophysics Data System (ADS)
Ohsaki, H.; Matsushita, N.; Koseki, T.; Tomita, M.
2014-05-01
The application of superconducting power cables to DC electric railway systems has been studied. It could leads to an effective use of regenerative brake, improved energy efficiency, effective load sharing among the substations, etc. In this study, an electric circuit model of a DC feeding system is built and numerical simulation is carried out using MATLAB-Simulink software. A modified electric circuit model with an AC power grid connection taken into account is also created to simulate the influence of the grid connection. The analyses have proved that a certain amount of energy can be conserved by introducing superconducting cables, and that electric load distribution and concentration among the substations depend on the substation output voltage distribution.
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NASA Astrophysics Data System (ADS)
Elangovan, D.; Archana, R.; Jayadeep, V. J.; Nithin, M.; Arunkumar, G.
2017-11-01
More than fifty percent Indian population do not have access to electricity in daily lives. The distance between the power generating stations and the distribution centers forms one of the main reasons for lack of electrification in rural and remote areas. Here lies the importance of decentralization of power generation through renewable energy resources. In the present world, electricity is predominantly powered by alternating current, but most day to day devices like LED lamps, computers and electrical vehicles, all run on DC power. By directly supplying DC to these loads, the number of power conversion stages was reduced, and overall system efficiency increases. Replacing existing AC network with DC is a humongous task, but with power electronic techniques, this project intends to implement DC grid at a household level in remote and rural areas. Proposed work was designed and simulated successfully for various loads amounting to 250 W through appropriate power electronic convertors. Maximum utilization of the renewable sources for domestic and commercial application was achieved with the proposed DC topology.
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Optimization of direct current-enhanced radiofrequency ablation: an ex vivo study.
Tanaka, Toshihiro; Isfort, Peter; Bruners, Philipp; Penzkofer, Tobias; Kichikawa, Kimihiko; Schmitz-Rode, Thomas; Mahnken, Andreas H
2010-10-01
The purpose of this study was to investigate the optimal setting for radiofrequency (RF) ablation combined with direct electrical current (DC) ablation in ex vivo bovine liver. An electrical circuit combining a commercially available RF ablation system with DC was developed. The negative electrode of a rectifier that provides DC was connected to a 3-cm multitined expandable RF probe. A 100-mH inductor was used to prevent electrical leakage from the RF generator. DC was applied for 15 min and followed by RF ablation in freshly excised bovine livers. Electric current was measured by an ammeter. Coagulation volume, ablation duration, and mean amperage were assessed for various DC voltages (no DC, 2.2, 4.5, and 9.0 V) and different RF ablation protocols (stepwise increase from 40 to 80 W, 40 W fixed, and 80 W fixed). Results were compared using Kruskal-Wallis and Mann-Whitney U test. Applying DC with 4.5 or 9.0 V, in combination with 40 W fixed or a stepwise increase of RF energy, resulted in significantly increased zone of ablation size compared with 2.2 V or no DC (P = 0.009). At 4.5 V DC, the stepwise increase of RF energy resulted in the same necrosis size as a 40 W fixed protocol (26.6 +/- 3.9 vs. 26.5 +/- 4.0 ml), but ablation duration was significantly decreased (296 +/- 85 s vs. 423 +/- 104 s; P = 0.028). Mean amperage was significantly lower at 4.5 V compared with 9.0 V (P = 0.028). Combining a stepwise increase of RF energy with a DC voltage of 4.5 V is most appropriate to increase coagulation volume and to minimize procedure time.
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Optimization of Direct Current-Enhanced Radiofrequency Ablation: An Ex Vivo Study
DOE Office of Scientific and Technical Information (OSTI.GOV)
Tanaka, Toshihiro, E-mail: toshihir@bf6.so-net.ne.jp; Isfort, Peter; Bruners, Philipp
2010-10-15
The purpose of this study was to investigate the optimal setting for radiofrequency (RF) ablation combined with direct electrical current (DC) ablation in ex vivo bovine liver. An electrical circuit combining a commercially available RF ablation system with DC was developed. The negative electrode of a rectifier that provides DC was connected to a 3-cm multitined expandable RF probe. A 100-mH inductor was used to prevent electrical leakage from the RF generator. DC was applied for 15 min and followed by RF ablation in freshly excised bovine livers. Electric current was measured by an ammeter. Coagulation volume, ablation duration, andmore » mean amperage were assessed for various DC voltages (no DC, 2.2, 4.5, and 9.0 V) and different RF ablation protocols (stepwise increase from 40 to 80 W, 40 W fixed, and 80 W fixed). Results were compared using Kruskal-Wallis and Mann-Whitney U test. Applying DC with 4.5 or 9.0 V, in combination with 40 W fixed or a stepwise increase of RF energy, resulted in significantly increased zone of ablation size compared with 2.2 V or no DC (P = 0.009). At 4.5 V DC, the stepwise increase of RF energy resulted in the same necrosis size as a 40 W fixed protocol (26.6 {+-} 3.9 vs. 26.5 {+-} 4.0 ml), but ablation duration was significantly decreased (296 {+-} 85 s vs. 423 {+-} 104 s; P = 0.028). Mean amperage was significantly lower at 4.5 V compared with 9.0 V (P = 0.028). Combining a stepwise increase of RF energy with a DC voltage of 4.5 V is most appropriate to increase coagulation volume and to minimize procedure time.« less
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Kim, Jocelyn T.; Liu, Yarong; Kulkarni, Rajan P.; Lee, Kevin K.; Dai, Bingbing; Lovely, Geoffrey; Ouyang, Yong; Wang, Pin; Yang, Lili; Baltimore, David
2018-01-01
Dendritic cell (DC) activation and antigen presentation are critical for efficient priming of T cell responses. Here, we study how lentiviral vectors (LVs) deliver antigen and activate DCs to generate T cell immunization in vivo. We report that antigenic proteins delivered in vector particles via pseudotransduction were sufficient to stimulate an antigen-specific immune response. The delivery of the viral genome encoding the antigen increased the magnitude of this response in vivo but was irrelevant in vitro. Activation of DCs by LVs was independent of MyD88, TRIF, and MAVS, ruling out an involvement of Toll-like receptor or RIG-I–like receptor signaling. Cellular DNA packaged in LV preparations induced DC activation by the host STING (stimulator of interferon genes) and cGAS (cyclic guanosine monophosphate–adenosine monophosphate synthase) pathway. Envelope-mediated viral fusion also activated DCs in a phosphoinositide 3-kinase–dependent but STING-independent process. Pseudotransduction, transduction, viral fusion, and delivery of cellular DNA collaborate to make the DC-targeted LV preparation an effective immunogen. PMID:28733470
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King, Robert Dean; DeDoncker, Rik Wivina Anna Adelson
1998-01-01
A method and apparatus for load leveling of a battery in an electrical power system includes a power regulator coupled to transfer power between a load and a DC link, a battery coupled to the DC link through a first DC-to-DC converter and an auxiliary passive energy storage device coupled to the DC link through a second DC-to-DC converter. The battery is coupled to the passive energy storage device through a unidirectional conducting device whereby the battery can supply power to the DC link through each of the first and second converters when battery voltage exceeds voltage on the passive storage device. When the load comprises a motor capable of operating in a regenerative mode, the converters are adapted for transferring power to the battery and passive storage device. In this form, resistance can be coupled in circuit with the second DC-to-DC converter to dissipate excess regenerative power.
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King, R.D.; DeDoncker, R.W.A.A.
1998-01-20
A method and apparatus for load leveling of a battery in an electrical power system includes a power regulator coupled to transfer power between a load and a DC link, a battery coupled to the DC link through a first DC-to-DC converter and an auxiliary passive energy storage device coupled to the DC link through a second DC-to-DC converter. The battery is coupled to the passive energy storage device through a unidirectional conducting device whereby the battery can supply power to the DC link through each of the first and second converters when battery voltage exceeds voltage on the passive storage device. When the load comprises a motor capable of operating in a regenerative mode, the converters are adapted for transferring power to the battery and passive storage device. In this form, resistance can be coupled in circuit with the second DC-to-DC converter to dissipate excess regenerative power. 8 figs.
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Five years of full-scale utility demonstration of pulsed energization of electric precipitators
DOE Office of Scientific and Technical Information (OSTI.GOV)
Schultz, S.A.; Jacobus, P.L.; Casey, P.J.
1996-11-01
In a conventional electrostatic precipitator (ESP) the applied dc voltage fulfills three functions: (1) generation of negative ions, (2) charging of particles, and (3) transport of the charged particles to the collecting plates. In the case of high resistivity fly-ash (often associated with the burning of low sulfur coal) the dc voltage is limited by repeated electrical discharges and in extreme cases by back-corona. Lowering the applied dc voltage reduces sparking and back-corona, but also reduces the field on the discharge wires and leads to poorly distributed ion generation as well as reduced charging and particle transport forces. Pulsed energization,more » which consists of superimposing high voltage pulses of short duration onto the existing base dc voltage, offers an attractive way to improve the collection efficiency of ESPs suffering from poor energization. The superimposed pulses become responsible for uniform ion generation while the underlying dc field continues to fulfill the function of particle charging and transport. This paper describes the five-year test of the ESP at Madison Gas and Electric`s Blount Station.« less
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Electric control of wave vector filtering in a hybrid magnetic-electric-barrier nanostructure
NASA Astrophysics Data System (ADS)
Kong, Yong-Hong; Lu, Ke-Yu; He, Ya-Ping; Liu, Xu-Hui; Fu, Xi; Li, Ai-Hua
2018-06-01
We theoretically investigate how to manipulate the wave vector filtering effect by a traverse electric field for electrons across a hybrid magnetic-electric-barrier nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe and a Schottky-metal stripe on top and bottom of a GaAs/Al x Ga1- x As heterostructure, respectively. The wave vector filtering effect is found to be related closely to the applied electric field. Moreover, the wave vector filtering efficiency can be manipulated by changing direction or adjusting strength of the traverse electric field. Therefore, such a nanostructure can be employed as an electrically controllable electron-momentum filter for nanoelectronics applications.
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Lymphocyte Electrotaxis in vitro and in vivo
Lin, Francis; Baldessari, Fabio; Gyenge, Christina Crenguta; Sato, Tohru; Chambers, Robert D.; Santiago, Juan G.; Butcher, Eugene C.
2008-01-01
Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including penetrating injury to epithelial barriers. An applied electric field with strength within the physiologic range can induce directional cell migration (i.e. electrotaxis) of epithelial cells, endothelial cells, fibroblasts, and neutrophils suggesting a potential role in cell positioning during wound healing. In the present study, we investigated the ability of lymphocytes to respond to applied direct current (DC) electric fields. Using a modified transwell assay and a simple microfluidic device, we show that human peripheral blood lymphocytes migrate toward the cathode in physiologically relevant DC electric fields. Additionally, electrical stimulation activates intracellular kinase signaling pathways shared with chemotactic stimuli. Finally, video microscopic tracing of GFP-tagged immunocytes in the skin of mouse ears reveals that motile cutaneous T cells actively migrate toward the cathode of an applied DC electric field. Lymphocyte positioning within tissues can thus be manipulated by externally applied electric fields, and may be influenced by endogenous electrical potential gradients as well. PMID:18684937
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Lymphocyte electrotaxis in vitro and in vivo.
Lin, Francis; Baldessari, Fabio; Gyenge, Christina Crenguta; Sato, Tohru; Chambers, Robert D; Santiago, Juan G; Butcher, Eugene C
2008-08-15
Electric fields are generated in vivo in a variety of physiologic and pathologic settings, including penetrating injury to epithelial barriers. An applied electric field with strength within the physiologic range can induce directional cell migration (i.e., electrotaxis) of epithelial cells, endothelial cells, fibroblasts, and neutrophils suggesting a potential role in cell positioning during wound healing. In the present study, we investigated the ability of lymphocytes to respond to applied direct current (DC) electric fields. Using a modified Transwell assay and a simple microfluidic device, we show that human PBLs migrate toward the cathode in physiologically relevant DC electric fields. Additionally, electrical stimulation activates intracellular kinase signaling pathways shared with chemotactic stimuli. Finally, video microscopic tracing of GFP-tagged immunocytes in the skin of mouse ears reveals that motile cutaneous T cells actively migrate toward the cathode of an applied DC electric field. Lymphocyte positioning within tissues can thus be manipulated by externally applied electric fields, and may be influenced by endogenous electrical potential gradients as well.
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Electrical and Biological Effects of Transmission Lines: A Review.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lee, Jack M.
1989-06-01
This review describes the electrical properties of a-c and d-c transmission lines and the resulting effects on plants, animals, and people. Methods used by BPA to mitigate undesirable effects are also discussed. Although much of the information in this review pertains to high-voltage transmission lines, information on distribution lines and electrical appliances is included. The electrical properties discussed are electric and magnetic fields and corona: first for alternating-current (a-c) lines, then for direct current (d-c).
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Electric vehicle system for charging and supplying electrical power
Su, Gui Jia
2010-06-08
A power system that provides power between an energy storage device, an external charging-source/load, an onboard electrical power generator, and a vehicle drive shaft. The power system has at least one energy storage device electrically connected across a dc bus, at least one filter capacitor leg having at least one filter capacitor electrically connected across the dc bus, at least one power inverter/converter electrically connected across the dc bus, and at least one multiphase motor/generator having stator windings electrically connected at one end to form a neutral point and electrically connected on the other end to one of the power inverter/converters. A charging-sourcing selection socket is electrically connected to the neutral points and the external charging-source/load. At least one electronics controller is electrically connected to the charging-sourcing selection socket and at least one power inverter/converter. The switch legs in each of the inverter/converters selected by the charging-source/load socket collectively function as a single switch leg. The motor/generators function as an inductor.
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NASA Technical Reports Server (NTRS)
Jandhyala, Vikram (Inventor); Chowdhury, Indranil (Inventor)
2011-01-01
An approach that efficiently solves for a desired parameter of a system or device that can include both electrically large fast multipole method (FMM) elements, and electrically small QR elements. The system or device is setup as an oct-tree structure that can include regions of both the FMM type and the QR type. An iterative solver is then used to determine a first matrix vector product for any electrically large elements, and a second matrix vector product for any electrically small elements that are included in the structure. These matrix vector products for the electrically large elements and the electrically small elements are combined, and a net delta for a combination of the matrix vector products is determined. The iteration continues until a net delta is obtained that is within predefined limits. The matrix vector products that were last obtained are used to solve for the desired parameter.
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Electric field modulated ferromagnetism in ZnO films deposited at room temperature
NASA Astrophysics Data System (ADS)
Bu, Jianpei; Liu, Xinran; Hao, Yanming; Zhou, Guangjun; Cheng, Bin; Huang, Wei; Xie, Jihao; Zhang, Heng; Qin, Hongwei; Hu, Jifan
2018-04-01
The ZnO film deposited at room temperature, which is composed of the amorphous-phase background plus a few nanograins or nanoclusters (about 1-2 nm), exhibits room temperature ferromagnetism (FM). Such FM is found to be connected with oxygen vacancies. For the Ta/ZnO/Pt device based on the medium layer ZnO deposited at room temperature, the saturation magnetization not only is modulated between high and low resistive states by electric voltage with DC loop electric current but also increases/decreases through adjusting the magnitudes of positive/negative DC sweeping voltage. Meanwhile, the voltage-controlled conductance quantization is observed in Ta/ZnO/Pt, accompanying the voltage-controlled magnetization. However, the saturation magnetization of the Ta/ZnO/Pt device becomes smaller under positive electric voltage and returns in some extent under negative electric voltage, when the DC loop electric current is not applied.
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Modeling of the coupled magnetospheric and neutral wind dynamos
NASA Technical Reports Server (NTRS)
Thayer, J. P.; Vickrey, J. F.; Heelis, R. A.; Gary, J. B.
1995-01-01
Work at SRI involved modeling the exchange of electromagnetic energy between the ionosphere and magnetosphere to help interpret the DE-B Poynting flux observations. To describe the electrical properties of the high-latitude ionosphere, we constructed a numerical model, from the framework provided by the Vector Spherical Harmonic (VSH) model, that determines the ionospheric currents, conductivities, and electric fields including both magnetospheric inputs and neutral wind dynamo effects. This model development grew from the earlier question of whether an electrical energy source in the ionosphere was capable of providing an upward Poynting flux. The model solves the steady-state neutral wind dynamo equations and the Poynting flux equation to provide insight into the electrodynamic role of the neutral winds. The modeling effort to determine the high-latitude energy flux has been able to reproduce many of the large-scale features observed in the Poynting flux measurements made by DE-2. Because the Poynting flux measurement is an integrated result of energy flux into or out of the ionosphere, we investigated the ionospheric properties that may contribute to the observed flux of energy measured by the spacecraft. During steady state the electromagnetic energy flux, or DC Poynting flux, is equal to the Joule heating rate and the mechanical energy transfer rate in the high-latitude ionosphere. Although the Joule heating rate acts as an energy sink, transforming electromagnetic energy into thermal or internal energy of the gas, the mechanical energy transfer rate may be either a sink or source of electromagnetic energy. In the steady state, it is only the mechanical energy transfer rate that can generate electromagnetic energy and result in a DC Poynating flux that is directed out of the ionosphere.
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Detection of γ-radiation and heavy metals using electrochemical bacterial-based sensor
NASA Astrophysics Data System (ADS)
Al-Shanawa, M.; Nabok, A.; Hashim, A.; Smith, T.; Forder, S.
2013-06-01
The main aim of this work is to develop a simple electrochemical sensor for detection of γ-radiation and heavy metals using bacteria. A series of DC and AC electrical measurements were carried out on samples of two types of bacteria, namely Escherichia coli and Deinococcus radiodurans. As a first step, a correlation between DC and AC electrical conductivity and bacteria concentration in solution was established. The study of the effect of γ-radiation and heavy metal ions (Cd2+) on DC and AC electrical characteristics of bacteria revealed a possibility of pattern recognition of the above inhibition factors.
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Tunable terahertz optical properties of graphene in dc electric fields
NASA Astrophysics Data System (ADS)
Dong, H. M.; Huang, F.; Xu, W.
2018-03-01
We develop a simple theoretical approach to investigate terahertz (THz) optical properties of monolayer graphene in the presence of an external dc electric field. The analytical results for optical coefficients such as the absorptance and reflectivity are obtained self-consistently on the basis of a diagrammatic self-consistent field theory and a Boltzmann equilibrium equation. It is found that the optical refractive index, reflectivity and conductivity can be effectively tuned by not only a gate voltage but also a driving dc electric field. This study is relevant to the applications of graphene as advanced THz optoelectronic devices.
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NASA Astrophysics Data System (ADS)
Matsuda, S.; Kasaba, Y.; Ishisaka, K.; Kasahara, Y.; Imachi, T.; Yagitani, S.; Kojima, H.; Kurita, S.; Shoji, M.; Hori, T.; Shinbori, A.; Teramoto, M.; Miyoshi, Y.; Nakagawa, T.; Takahashi, N.; Nishimura, Y.; Matsuoka, A.; Tsuchiya, F.; Kumamoto, A.; Nomura, R.
2017-12-01
This paper summarizes the specifications and the evaluation results of Wire Probe Antenna (WPT) and Electric Field Detector (EFD), which are the key parts of Plasma Wave Experiment (PWE) aboard the Arase satellite, in their initial operations and the beginning phase of the full observations. WPT consists of the two dipole antennas as electric field sensors with 32m tip-to-tip length, with a sphere probe (6 cm diameter) attached at each end of wires (length: 15-m). They are extended orthogonally in the spin plane which is roughly perpendicular to the Sun. It enables the PWE to measure the E-field from DC to 10 MHz. This system is almost compatible to the WPT of the Plasma Wave Investigation (PWI) aboard BepiColombo Mercury Magnetospheric Orbiter, except the material of the spherical probe (ERG: Aluminium alloy, MMO: Titanium-alloy). This paper shows the extended length evaluated by the Lorentz force (spacecraft velocity x B-field) and the antenna impedance as the basic information of the E-field measurement capability of the PWE E-field receivers, with the evaluation for the possible degradation of the probe surface coated by TiAlN as BepiColombo. EFD is the 2-channel low frequency electric receiver as a part of EWO (EFD/WFC/OFA), for the measurement of 2ch electric field in the spin-plane with the sampling rate of 512 Hz (dynamic range: +-200 mV/m, +-3 V/m) and the 4ch spacecraft potential with the sampling rate of 128 Hz (dynamic range: +-100 V), respectively, with the bias control capability fed to the WPT probes. The electric field in DC - 232Hz provides the capability to detect (1) the fundamental information of the plasma dynamics and accelerations and (2) the characteristics of MHD and ion waves with their Poynting vectors with the data measured by MGF and PWE/WFC-B connected to PWE/SCM. The spacecraft potential provides the electron density information with UHR frequency. This paper also introduces the data sets and their calibration status.
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NASA Astrophysics Data System (ADS)
Seo, In-jin; Choi, Won; Seong, Jae-gyu; Lee, Bang-wook; Koo, Ja-yoon
2014-08-01
It has been reported that the insulation design under DC stress is considered as one of the critical factors in determining the performance of high-voltage direct current (HVDC) superconducting cable. Therefore, it is fundamentally necessary to investigate the DC breakdown characteristics of the composite insulation system consisting of liquid nitrogen (LN2)/polypropylene-laminated-paper (PPLP). In particular, the insulation characteristics under DC polarity reversal condition should be verified to understand the polarity effect of the DC voltage considering the unexpected incidents taking place at line-commutated-converters (LCC) under service at a DC power grid. In this study, to examine the variation of DC electric field strength, the step voltage and polarity reversal breakdown tests are performed under DC stress. Also, we investigate the electric field distributions in a butt gap of the LN2/PPLP condition considering the DC polarity reversal by using simulation software.
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NASA Astrophysics Data System (ADS)
Lee, Dukhyung; Kim, Dai-Sik
2016-01-01
We study light scattering off rectangular slot nano antennas on a metal film varying incident polarization and incident angle, to examine which field vector of light is more important: electric vector perpendicular to, versus magnetic vector parallel to the long axis of the rectangle. While vector Babinet’s principle would prefer magnetic field along the long axis for optimizing slot antenna function, convention and intuition most often refer to the electric field perpendicular to it. Here, we demonstrate experimentally that in accordance with vector Babinet’s principle, the incident magnetic vector parallel to the long axis is the dominant component, with the perpendicular incident electric field making a small contribution of the factor of 1/|ε|, the reciprocal of the absolute value of the dielectric constant of the metal, owing to the non-perfectness of metals at optical frequencies.
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NASA Astrophysics Data System (ADS)
Khan, Mansoor; Yong, Wang; Mustafa, Ehtasham
2017-07-01
After the rapid advancement in the field of power electronics devices and drives for last few decades, there are different kinds of Pulse Width Modulation techniques which have been brought to the market. The applications ranging from industrial appliances to military equipment including the home appliances. The vey common application for the PWM is three phase voltage source inverter, which is used to convert DC to AC in the homes to supply the power to the house in case electricity failure, usually named as Un-interrupted Power Supply. In this paper Space Vector Pulse Width Modulation techniques is discussed and analysed under the control technique named as Field Oriented Control. The working and implementation of this technique has been studied by implementing on the three phase bridge inverter. The technique is used to control the Permanente Magnet Synchronous Motor. The drive system is successfully implemented in MATLAB/Simulink using the mathematical equation and algorithm to achieve the satisfactory results. PI type of controller is used to tuned ers of the motothe parametr i.e. torque and current.
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ERIC Educational Resources Information Center
Deal, Walter F., III
2004-01-01
This article discusses electric motors and the many ways in which they are used. Selecting the most appropriate miniature DC electric motor wisely will contribute toward success and satisfaction in designing and building motorized projects and activities. Typical parts suppliers stock a variety of miniature DC motors and provide sufficient…
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Converter topologies and control
Rodriguez, Fernando; Qin, Hengsi; Chapman, Patrick
2018-05-01
An inverter includes a transformer that includes a first winding, a second winding, and a third winding, a DC-AC inverter electrically coupled to the first winding of the transformer, a cycloconverter electrically coupled to the second winding of the transformer, an active filter electrically coupled to the third winding of the transformer. The DC-AC inverter is adapted to convert the input DC waveform to an AC waveform delivered to the transformer at the first winding. The cycloconverter is adapted to convert an AC waveform received at the second winding of the transformer to the output AC waveform having a grid frequency of the AC grid. The active filter is adapted to sink and source power with one or more energy storage devices based on a mismatch in power between the DC source and the AC grid.
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Lu, Bin; Yang, Yi; Sharma, Santosh K; Zambare, Prachi; Madane, Mayura A
2014-12-23
A method identifies electric load types of a plurality of different electric loads. The method includes providing a load feature database of a plurality of different electric load types, each of the different electric load types including a first load feature vector having at least four different load features; sensing a voltage signal and a current signal for each of the different electric loads; determining a second load feature vector comprising at least four different load features from the sensed voltage signal and the sensed current signal for a corresponding one of the different electric loads; and identifying by a processor one of the different electric load types by determining a minimum distance of the second load feature vector to the first load feature vector of the different electric load types of the load feature database.
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Power processing and control requirements of dispersed solar thermal electric generation systems
NASA Technical Reports Server (NTRS)
Das, R. L.
1980-01-01
Power Processing and Control requirements of Dispersed Receiver Solar Thermal Electric Generation Systems are presented. Kinematic Stirling Engines, Brayton Engines and Rankine Engines are considered as prime movers. Various types of generators are considered for ac and dc link generations. It is found that ac-ac Power Conversion is not suitable for implementation at this time. It is also found that ac-dc-ac Power Conversion with a large central inverter is more efficient than ac-dc-ac Power Conversion using small dispersed inverters. Ac-link solar thermal electric plants face potential stability and synchronization problems. Research and development efforts are needed in improving component performance characteristics and generation efficiency to make Solar Thermal Electric Generation economically attractive.
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Synthesis of zirconium oxynitride in air under DC electric fields
DOE Office of Scientific and Technical Information (OSTI.GOV)
Morisaki, Nobuhiro; Tokunaga, Tomoharu; Sasaki, Katsuhiro
We synthesized zirconium oxynitride from yttria-stabilized zirconia (YSZ) in air by applying DC electric fields that produced a controlled electric current in the specimen. When YSZ was heated under an applied DC electric field, the electric current of the specimen steeply increased at a critical temperature, called a flash event, during flash sintering. By keeping the electric current of the specimen constant during the flash event and then holding the specimen at the critical temperature, YSZ was transformed into zirconium oxynitride under the optimal conditions of 50 V/cm, 500 mA, and 1000 °C. We confirmed that zirconium oxynitride formed using high-resolution transmission electronmore » microscopy, electron energy-loss spectroscopy, and energy-dispersive spectrometry. To convert oxides to nitrides, reducing conditions are necessary to form excess oxygen vacancies. Our technique produced the strong reducing conditions necessary to form nitrides from the oxides by delivering a controlled electric current to the specimen.« less
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A comparative study of electric power distribution systems for spacecraft
NASA Technical Reports Server (NTRS)
Stuart, Thomas A.; King, Roger J.
1990-01-01
The electric power distribution systems for spacecraft are compared concentrating on two interrelated issues: the choice between dc and high frequency ac, and the converter/inverter topology to be used at the power source. The relative merits of dc and ac distribution are discussed. Specific converter and inverter topologies are identified and analyzed in detail for the purpose of detailed comparison. Finally, specific topologies are recommended for use in dc and ac systems.
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Electrical properties of PMMA ion-implanted with low-energy Si+ beam
NASA Astrophysics Data System (ADS)
Hadjichristov, G. B.; Gueorguiev, V. K.; Ivanov, Tz E.; Marinov, Y. G.; Ivanov, V. G.; Faulques, E.
2010-01-01
The electrical properties of polymethylmethacrylate (PMMA) after implantation with silicon ions accelerated to an energy of 50 keV are studied under DC electric bias field. The electrical response of the formed material is examined as a function of Si+ fluence in the range 1014 - 1017 cm-2. The carbonaceous subsurface region of the Si+-implanted PMMA displays a significant DC conductivity and a sizable field effect that can be used for electronic applications.
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Sea Mines and Countermeasures: A Bibliography. Revision
2007-07-01
days. " Vector polarization filtering" was employed to separate the reflected signal due to Rayleigh waves, for which the particle motion is...buried mines. Rayleigh waves are unique in that they have elliptical particle motion that allows one to use vector polarization filtering to separate...D. Vector Acoustic Mine Mechanism. Patent. Washington, DC: Department of the Navy, February 1980. 11p. ABSTRACT: This patent discloses a submarine
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Murik, S E; Shapkin, A G
2004-08-01
It has been proposed to assess functional and metabolic state of the brain nervous tissue in terms of bioelectrical parameters. Simultaneous recording of the DC potential level and total slow electrical activity of the nervous tissue was performed in the object of study by nonpolarizable Ag/AgCl electrodes with a DC amplifier. The functional and metabolic state of the brain was determined in terms of enhancement or reduction in the total slow electrical activity and positive or negative shifts in the DC potential level.
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NASA Astrophysics Data System (ADS)
Grainger, Brandon Michael
The growth in the electric power industry's portfolio of Direct Current (DC) based generation and loads have captured the attention of many leading research institutions. Opportunities for using DC based systems have been explored in electric ship design and have been a proven, reliable solution for transmitting bulk power onshore and offshore. To integrate many of the renewable resources into our existing AC grid, a number of power conversions through power electronics are required to condition the equipment for direct connection. Within the power conversion stages, there is always a requirement to convert to or from DC. The AC microgrid is a conceptual solution proposed for integrating various types of renewable generation resources. The fundamental microgrid requirements include the capability of operating in islanding mode and/or grid connected modes. The technical challenges associated with microgrids include (1) operation modes and transitions that comply with IEEE1547 without extensive custom engineering and (2) control architecture and communication. The Medium Voltage DC (MVDC) architecture, explored by the University of Pittsburgh, can be visualized as a special type of DC microgrid. This dissertation is multi-faceted, focused on many design aspects of an offshore DC microgrid. The focal points of the discussion are focused on optimized high power, high frequency magnetic material performance in electric machines, transformers, and DC/DC power converters---all components found within offshore, power system architectures. A new controller design based upon model reference control is proposed and shown to stabilize the electric motor drives (modeled as constant power loads), which serve as the largest power consuming entities in the microgrid. The design and simulation of a state-of-the-art multilevel converter for High Voltage DC (HVDC) is discussed and a component sensitivity analysis on fault current peaks is explored. A power management routine is proposed and evaluated as the DC microgrid is disturbed through various mode transitions. Finally, two communication protocols are described for the microgrid---one to minimize communication overhead inside the microgrid and another to provide robust and scalable intra-grid communication. The work presented is supported by Asea Brown Boveri (ABB) Corporate Research Center within the Active Grid Infrastructure program, the Advanced Research Project Agency - Energy (ARPA-E) through the Solar ADEPT program, and Mitsubishi Electric Corporation (MELCO).
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Nawwab Al-Deen, F M; Selomulya, C; Kong, Y Y; Xiang, S D; Ma, C; Coppel, R L; Plebanski, M
2014-02-01
Dendritic cells (DC) targeting vaccines require high efficiency for uptake, followed by DC activation and maturation. We used magnetic vectors comprising polyethylenimine (PEI)-coated superparamagnetic iron oxide nanoparticles, with hyaluronic acid (HA) of different molecular weights (<10 and 900 kDa) to reduce cytotoxicity and to facilitate endocytosis of particles into DCs via specific surface receptors. DNA encoding Plasmodium yoelii merozoite surface protein 1-19 and a plasmid encoding yellow fluorescent gene were added to the magnetic complexes with various % charge ratios of HA: PEI. The presence of magnetic fields significantly enhanced DC transfection and maturation. Vectors containing a high-molecular-weight HA with 100% charge ratio of HA: PEI yielded a better transfection efficiency than others. This phenomenon was attributed to their longer molecular chains and higher mucoadhesive properties aiding DNA condensation and stability. Insights gained should improve the design of more effective DNA vaccine delivery systems.
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Control of Grid Connected Photovoltaic System Using Three-Level T-Type Inverter
NASA Astrophysics Data System (ADS)
Zorig, Abdelmalik; Belkeiri, Mohammed; Barkat, Said; Rabhi, Abdelhamid
2016-08-01
Three-level T-Type inverter (3LT2I) topology has numerous advantageous compared to three-level neutral-point-clamped (NPC) inverter. The main benefits of 3LT2I inverter are the efficiency, inverter cost, switching losses, and the quality of output voltage waveforms. In this paper, a photovoltaic distributed generation system based on dual-stage topology of DC-DC boost converter and 3LT2I is introduced. To that end, a decoupling control strategy of 3LT2I is proposed to control the current injected into the grid, reactive power compensation, and DC-link voltage. The resulting system is able to extract the maximum power from photovoltaic generator, to achieve sinusoidal grid currents, and to ensure reactive power compensation. The voltage-balancing control of two split DC capacitors of the 3LT2I is achieved using three-level space vector modulation with balancing strategy based on the effective use of the redundant switching states of the inverter voltage vectors. The proposed system performance is investigated at different operating conditions.
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Luo, Jie; Cai, Limei; Qi, Shihua; Wu, Jian; Sophie Gu, Xiaowen
2018-03-01
Direct and alternating current electric fields with various voltages were used to improve the decontamination efficiency of chelator assisted phytoremediation for multi-metal polluted soil. The alleviation effect of electric field on leaching risk caused by chelator application during phytoremediation process was also evaluated. Biomass yield, pollutant uptake and metal leaching retardation under alternating current (AC) and direct current (DC) electric fields were compared. The biomass yield of Eucalyptus globulus under AC fields with various voltages (2, 4 and 10 V) were 3.91, 4.16 and 3.67kg, respectively, significantly higher than the chelator treatment without electric field (2.71kg). Besides growth stimulation, AC fields increased the metal concentrations of plant tissues especially in aerial parts manifested by the raised translocation factor of different metals. Direct current electric fields with low and moderate voltages increased the biomass production of the species to 3.45 and 3.12kg, respectively, while high voltage on the contrary suppressed the growth of the plants (2.66kg). Under DC fields, metal concentrations elevated obviously with increasing voltages and the metal translocation factors were similar under all voltages. Metal extraction per plant achieved the maximum value under moderate voltage due to the greatest biomass production. DC field with high voltage (10V) decreased the volume of leachate from the chelator treatment without electric field from 1224 to 56mL, while the leachate gathered from AC field treatments raised from 512 to 670mL. DC field can retard the downward movement of metals caused by chelator application more effectively relative to AC field due to the constant water flow and electroosmosis direction. Alternating current field had more promotive effect on chelator assisted phytoremediation efficiency than DC field illustrated by more metal accumulation in the species. However, with the consideration of leaching risk, DC field with moderate voltage was the optimal supplementary technique for phytoremediation. Copyright © 2017 Elsevier Inc. All rights reserved.
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A Lemon Cell Battery for High-Power Applications
ERIC Educational Resources Information Center
Muske, Kenneth R.; Nigh, Christopher W.; Weinstein, Randy D.
2007-01-01
The use of lemon cell battery to run an electric DC motor is demonstrated for chemistry students. This demonstration aids the students in understanding principles behind the design and construction of the lemon cell battery and principles governing the electric DC motor and other basic principles.
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NASA Technical Reports Server (NTRS)
Lebron, Ramon C.; Oliver, Angela C.; Bodi, Robert F.
1991-01-01
Power components hardware in support of the Space Station Freedom dc Electrical Power System were tested. One type of breadboard hardware tested is the dc Load Converter Unit, which constitutes the power interface between the electric power system and the actual load. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. Three load converters were tested: a series resonant converter, a series inductor switchmode converter, and a switching full-bridge forward converter. The topology, operation principles, and tests results are described, in general. A comparative analysis of the three units is given with respect to efficiency, regulation, short circuit behavior (protection), and transient characteristics.
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Integrated Inverter For Driving Multiple Electric Machines
Su, Gui-Jia [Knoxville, TN; Hsu, John S [Oak Ridge, TN
2006-04-04
An electric machine drive (50) has a plurality of inverters (50a, 50b) for controlling respective electric machines (57, 62), which may include a three-phase main traction machine (57) and two-phase accessory machines (62) in a hybrid or electric vehicle. The drive (50) has a common control section (53, 54) for controlling the plurality of inverters (50a, 50b) with only one microelectronic processor (54) for controlling the plurality of inverters (50a, 50b), only one gate driver circuit (53) for controlling conduction of semiconductor switches (S1-S10) in the plurality of inverters (50a, 50b), and also includes a common dc bus (70), a common dc bus filtering capacitor (C1) and a common dc bus voltage sensor (67). The electric machines (57, 62) may be synchronous machines, induction machines, or PM machines and may be operated in a motoring mode or a generating mode.
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Electric-field-induced flow-aligning state in a nematic liquid crystal.
Fatriansyah, Jaka Fajar; Orihara, Hiroshi
2015-04-01
The response of shear stress to a weak ac electric field as a probe is measured in a nematic liquid crystal under shear flow and dc electric fields. Two states with different responses are clearly observed when the dc electric field is changed at a constant shear rate: the flow aligning and non-flow aligning states. The director lies in the shear plane in the flow aligning state and out of the plane in the non-flow aligning state. Through application of dc electric field, the non-flow aligning state can be changed to the flow aligning state. In the transition from the flow aligning state to the non-flow aligning state, it is found that the response increases and the relaxation time becomes longer. Here, the experimental results in the flow aligning state are discussed on the basis of the Ericksen-Leslie theory.
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Wang, Fei-Xiang; Yuan, Ling; Huang, Jian-Guo
2013-06-01
In order to detect toxicants sensitively in water by phototaxity of Daphnia, we studied the influence of DC electric field on phototaxity of self-bred Daphnia carinata, a mono-clone with high phototaxity, and the changes of their phototaxity in response to Cr6+ and Hg2+ after the treatment of DC electric field. The result indicated that the treatment of DC electric field changed their phototaxical indexes from positive to negative as the electric density increased and the time prolonged. The criteria values that showed no sign of changes in the phototaxical index of Daphnia carinata were 0.01 mA for 5 min. However, the limit for detecting Cr6+ and Hg2+ by their phototaxical index decreased significantly after treatment with 0.01 mA/5 min. The detection limits were only 32 microg x L(-1) for Cr6+ and 4.2 microg x L(-1) for Hg2+ after this treatment, much lower than those without pretreatment (56 microg x L(-1) for Cr6+ and 5.6 microg x L(-1) for Hg2+, respectively). Therefore, appropriate DC electric field to pre-treat Daphnia could decrease the detection limit, widen the concentration range of detection, and increased the sensibilities in water monitoring.
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Electroosmotic Flow Driven by DC and AC Electric Fields in Curved Microchannels
NASA Astrophysics Data System (ADS)
Chen, Jia-Kun; Luo, Win-Jet; Yang, Ruey-Jen
2006-10-01
The purpose of this study is to investigate electroosmotic flows driven by externally applied DC and AC electric fields in curved microchannels. For the DC electric driving field, the velocity distribution and secondary flow patterns are investigated in microchannels with various curvature ratios. We use the Dean number to describe the curvature effect of the flow field in DC electric field. The result implies that the effect of curvatures and the strength of the secondary flows become get stronger when the curvature ratio of C/A (where C is the radius of curvature of the microchannel and A is the half-height of rectangular curved tube.) is smaller. For the AC electric field, the velocity distribution and secondary flow patterns are investigated for driving frequencies in the range of 2.0 kHz (\\mathit{Wo}=0.71) to 11 kHz (\\mathit{Wo}=1.66). The numerical results reveal that the velocity at the center of the microchannel becomes lower at higher frequencies of the AC electric field and the strength of the secondary flow decreases. When the applied frequency exceeds 3.0 kHz (\\mathit{Wo}=0.87), vortices are no longer observed at the corners of the microchannel. Therefore, it can be concluded that the secondary flow induced at higher AC electric field frequencies has virtually no effect on the axial flow field in the microchannel.
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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.
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King, Paul E [Corvallis, OR; Woodside, Charles Rigel [Corvallis, OR
2012-02-07
The disclosure herein provides an apparatus for location of a quantity of current vectors in an electrical device, where the current vector has a known direction and a known relative magnitude to an input current supplied to the electrical device. Mathematical constants used in Biot-Savart superposition equations are determined for the electrical device, the orientation of the apparatus, and relative magnitude of the current vector and the input current, and the apparatus utilizes magnetic field sensors oriented to a sensing plane to provide current vector location based on the solution of the Biot-Savart superposition equations. Description of required orientations between the apparatus and the electrical device are disclosed and various methods of determining the mathematical constants are presented.
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Electro-Mechanical Actuator. DC Resonant Link Controller
NASA Technical Reports Server (NTRS)
Schreiner, Kenneth E.
1996-01-01
This report summarizes the work performed on the 68 HP electro-mechanical actuator (EMA) system developed on NASA contract for the Electrical Actuation (ELA) Technology Bridging Program. The system was designed to demonstrate the capability of large, high power linear ELAs for applications such as Thrust Vector Control (TVC) on rocket engines. It consists of a motor controller, drive electronics and a linear actuator capable of up to 32,00 lbs loading at 7.4 inches/second. The drive electronics are based on the Resonant DC link concept and operate at a nominal frequency of 55 kHz. The induction motor is a specially designed high speed, low inertia motor capable of a 68 peak HP. The actuator was originally designed by MOOG Aerospace under an internal R & D program to meet Space Shuttle Main Engine (SSME) TVC requirements. The design was modified to meet this programs linear rate specification of 7.4 inches/second. The motor and driver were tested on a dynamometer at the Martin Marietta Space Systems facility. System frequency response, step response and force-velocity tests were conducted at the MOOG Aerospace facility. A complete description of the system and all test results can be found in the body of the report.
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Electrical safety for high voltage arrays
NASA Technical Reports Server (NTRS)
Marshall, N. A.
1983-01-01
A number of key electrical safety requirements for the high voltage arrays of central station photovoltaic power systems are explored. The suitability of representative industrial DC power switchgear for control and fault protection was evaluated. Included were AC/DC circuit breakers, electromechanical contactors and relays, load interruptors, cold disconnect devices, sectionalizing switches, and high voltage DC fuses. As appropriate, steady state and transient characteristics were analyzed. Failure modes impacting upon operation and maintenance safety were also identified, as were the voltage withstand and current interruption levels.
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Blondin, J P; Nguyen, D H; Sbeghen, J; Goulet, D; Cardinal, C; Maruvada, P S; Plante, M; Bailey, W H
1996-01-01
The objective of this study was to assess the ability of humans to detect the presence of DC electric field and ion currents. An exposure chamber simulating conditions present in the vicinity of high-voltage DC (HVDC) lines was designed and built for this purpose. In these experiments, the facility was used to expose observers to DC electric fields up to 50 kV/m and ion current densities up to 120 nA/m2. Forty-eight volunteers (25 women and 23 men) between the ages of 18 and 57 years served as observers. Perception of DC fields was examined by using two psychophysical methods: an adaptive staircase procedure and a rating method derived from signal-detection theory. Subjects completed three different series of observations by using each of these methods; one was conducted without ion currents, and the other two involved various combinations of electric fields and ion currents. Overall, subjects were significantly more likely to detect DC fields as the intensity increased. Observers were able to detect the presence of DC fields alone, but only at high intensities; the average threshold was 45 kV/m. Except in the most sensitive individuals, ion current densities up to 60 nA/m2 did not significantly facilitate the detection of DC fields. However, higher ion current densities were associated with a substantial lowering of sensory thresholds in a large majority of observers. Data analysis also revealed large variations in perceptual thresholds among observers. Normative data indicating DC field and ion current intensities that can be detected by 50% of all observers are provided. In addition, for the most sensitive observers, several other detection proportions were derived from the distribution of individual detection capabilities. These data can form the basis for environmental guidelines relating to the design of HVDC lines.
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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.
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Electrorotation of novel electroactive polymer composites in uniform DC and AC electric fields
NASA Astrophysics Data System (ADS)
Zrinyi, Miklós; Nakano, Masami; Tsujita, Teppei
2012-06-01
Novel electroactive polymer composites have been developed that could spin in uniform DC and AC electric fields. The angular displacement as well as rotation of polymer disks around an axis that is perpendicular to the direction of the applied electric field was studied. It was found that the dynamics of the polymer rotor is very complex. Depending on the strength of the static DC field, three regimes have been observed: no rotation occurs below a critical threshold field intensity, oscillatory motion takes place just above this value and continuous rotation can be observed above the critical threshold field intensity. It was also found that low frequency AC fields could also induce angular deformation.
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Rotation Detection Using the Precession of Molecular Electric Dipole Moment
NASA Astrophysics Data System (ADS)
Ke, Yi; Deng, Xiao-Bing; Hu, Zhong-Kun
2017-11-01
We present a method to detect the rotation by using the precession of molecular electric dipole moment in a static electric field. The molecular electric dipole moments are polarized under the static electric field and a nonzero electric polarization vector emerges in the molecular gas. A resonant radio-frequency pulse electric field is applied to realize a 90° flip of the electric polarization vector of a particular rotational state. After the pulse electric field, the electric polarization vector precesses under the static electric field. The rotation induces a shift in the precession frequency which is measured to deduce the angular velocity of the rotation. The fundamental sensitivity limit of this method is estimated. This work is only a proposal and does not involve experimental results.
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Power quality analysis of DC arc furnace operation using the Bowman model for electric arc
NASA Astrophysics Data System (ADS)
Gherman, P. L.
2018-01-01
This work is about a relatively new domain. The DC electric arc is superior to the AC electric arc and it’s not used in Romania. This is why we analyzed the work functions of these furnaces by simulation and model checking of the simulation results.The conclusions are favorable, to be carried is to develop a real-time control system of steel elaboration process.
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Rigorous theory of molecular orientational nonlinear optics
DOE Office of Scientific and Technical Information (OSTI.GOV)
Kwak, Chong Hoon, E-mail: chkwak@ynu.ac.kr; Kim, Gun Yeup
2015-01-15
Classical statistical mechanics of the molecular optics theory proposed by Buckingham [A. D. Buckingham and J. A. Pople, Proc. Phys. Soc. A 68, 905 (1955)] has been extended to describe the field induced molecular orientational polarization effects on nonlinear optics. In this paper, we present the generalized molecular orientational nonlinear optical processes (MONLO) through the calculation of the classical orientational averaging using the Boltzmann type time-averaged orientational interaction energy in the randomly oriented molecular system under the influence of applied electric fields. The focal points of the calculation are (1) the derivation of rigorous tensorial components of the effective molecularmore » hyperpolarizabilities, (2) the molecular orientational polarizations and the electronic polarizations including the well-known third-order dc polarization, dc electric field induced Kerr effect (dc Kerr effect), optical Kerr effect (OKE), dc electric field induced second harmonic generation (EFISH), degenerate four wave mixing (DFWM) and third harmonic generation (THG). We also present some of the new predictive MONLO processes. For second-order MONLO, second-order optical rectification (SOR), Pockels effect and difference frequency generation (DFG) are described in terms of the anisotropic coefficients of first hyperpolarizability. And, for third-order MONLO, third-order optical rectification (TOR), dc electric field induced difference frequency generation (EFIDFG) and pump-probe transmission are presented.« less
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Mathematical model for the dc-ac inverter for the Space Shuttle
NASA Technical Reports Server (NTRS)
Berry, Frederick C.
1987-01-01
The reader is informed of what was done for the mathematical modeling of the dc-ac inverter for the Space Shuttle. The mathematical modeling of the dc-ac inverter is an essential element in the modeling of the electrical power distribution system of the Space Shuttle. The electrical power distribution system which is present on the Space Shuttle is made up to 3 strings each having a fuel cell which provides dc to those systems which require dc, and the inverters which convert the dc to ac for those elements which require ac. The inverters are units which are 2 wire structures for the main dc inputs and 2 wire structures for the ac output. When 3 are connected together a 4 wire wye connection results on the ac side. The method of modeling is performed by using a Least Squares curve fitting method. A computer program is presented for implementation of the model along with graphs and tables to demonstrate the accuracy of the model.
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Chun, Sung-Yong
2013-03-01
Titanium nitride films used as an important electrode material for the design of alkali metal thermal-to-electric conversion (AMTEC) system have been prepared using dc (direct current) and asymmetric-bipolar pulsed dc magnetron sputtering. The pulse frequency and the duty cycle were varied from 5 to 50 kHz and 50 to 95%, respectively. The deposition rate, grain size and resistivity of pulsed dc sputtered films were decreased when the pulse frequency increased, while the nano hardness of titanium nitride films increased. We present in detail coatings (e.g., deposition rate, grain size, prefer-orientation, resistivity and hardness). Our studies show that titanium nitride coatings with superior properties can be prepared using asymmetric-bipolar pulsed dc sputtering.
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NASA Technical Reports Server (NTRS)
Lebron, Ramon C.; Oliver, Angela C.; Bodi, Robert F.
1991-01-01
Power components hardware in support of the Space Station freedom dc Electric Power System were tested. One type of breadboard hardware tested is the dc Load Converter Unit, which constitutes the power interface between the electric power system and the actual load. These units are dc to dc converters that provide the final system regulation before power is delivered to the load. Three load converters were tested: a series resonant converter, a series inductor switch-mode converter, and a switching full-bridge forward converter. The topology, operation principles, and test results are described, in general. A comparative analysis of the three units is given with respect to efficiency, regulation, short circuit behavior (protection), and transient characteristics.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, T.; Yang, Z.; Dong, P.
The cold-cathode Penning ion gauge (PIG) type ion source has been used for generation of negative hydrogen (H{sup -}) ions as the internal ion source of a compact cyclotron. A novel method called electrical shielding box dc beam measurement is described in this paper, and the beam intensity was measured under dc extraction inside an electrical shielding box. The results of the trajectory simulation and dc H{sup -} beam extraction measurement were presented. The effect of gas flow rate, magnetic field strength, arc current, and extraction voltage were also discussed. In conclusion, the dc H{sup -} beam current of aboutmore » 4 mA from the PIG ion source with the puller voltage of 40 kV and arc current of 1.31 A was extrapolated from the measurement at low extraction dc voltages.« less
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NASA Technical Reports Server (NTRS)
Nishikawa, K.-I.; Ganguli, G.; Lee, Y. C.; Palmadesso, P. J.
1989-01-01
A spatially two-dimensional electrostatic PIC simulation code was used to study the stability of a plasma equilibrium characterized by a localized transverse dc electric field and a field-aligned drift for L is much less than Lx, where Lx is the simulation length in the x direction and L is the scale length associated with the dc electric field. It is found that the dc electric field and the field-aligned current can together play a synergistic role to enable the excitation of electrostatic waves even when the threshold values of the field aligned drift and the E x B drift are individually subcritical. The simulation results show that the growing ion waves are associated with small vortices in the linear stage, which evolve to the nonlinear stage dominated by larger vortices with lower frequencies.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-11-08
... Adoption of Technical Specifications Task Force Traveler TSTF-500, Revision 2, ``DC Electrical Rewrite... Technical Specifications Task Force (TSTF) Traveler TSTF-500, Revision 2, ``DC Electrical Rewrite--Update to... Reactor Systems Engineer, Technical Specifications Branch, Mail Stop: O-7 C2A, Division of Inspection and...
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Trade Electricity. Motors & Controls--Level 3. Standardized Curriculum.
ERIC Educational Resources Information Center
New York City Board of Education, Brooklyn, NY. Office of Occupational and Career Education.
This curriculum guide consists of seven modules on motors and controls, one of the three divisions of the standardized trade electricity curriculum in high schools in New York City. The seven modules cover the following subjects: energy conservation wiring, direct current (DC) motor repair and rewinding, DC motor controls, alternating current (AC)…
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ERIC Educational Resources Information Center
Kraftmakher, Yaakov
2010-01-01
Experiments with an electric motor provide good opportunity to demonstrate some basic laws of electricity and magnetism. The aim of the experiments with a low-power dc motor is to show how the motor approaches its steady rotation and how its torque, mechanical power and efficiency depend on the rotation velocity. The tight relationship between the…
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NASA Astrophysics Data System (ADS)
Aziz, Shujahadeen B.; Rasheed, Mariwan A.; Abidin, Zul H. Z.
2017-10-01
Optical and electrical properties of nanocomposite solid polymer electrolytes based on chitosan have been investigated. Incorporation of alumina nanoparticles into the chitosan:silver triflate (AgTf) system broadened the surface plasmon resonance peaks of the silver nanoparticles and shifted the absorption edge to lower photon energy. A clear decrease of the optical bandgap in nanocomposite samples containing alumina nanoparticles was observed. The variation of the direct-current (DC) conductivity and dielectric constant followed the same trend with alumina concentration. The DC conductivity increased by two orders of magnitude, which can be attributed to hindrance of silver ion reduction. Transmission electron microscopy was used to interpret the space-charge and blocking effects of alumina nanoparticles on the DC conductivity and dielectric constant. The ion conduction mechanism was interpreted based on the dependences of the electrical and dielectric parameters. The dependence of the DC conductivity on the dielectric constant is explained empirically. Relaxation processes associated with conductivity and viscoelasticity were distinguished based on the incomplete semicircular arcs in plots of the real and imaginary parts of the electric modulus.
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Effect of neodymium substitution on the electric and dielectric properties of Mn-Ni-Zn ferrite
NASA Astrophysics Data System (ADS)
Agami, W. R.
2018-04-01
Ferrite samples of Mn0.5Ni0.1Zn0.4NdxFe2-xO4 (x = 0.0, 0.01, 0.02, 0.05, 0.075 and 0.1) have been prepared by usual ceramic method. The temperature and composition dependences of the dc electric resistivity (ρdc) were studied. The frequency and composition dependences of the ac electric resistivity (ρac) and dielectric parameters (dielectric constant ε' and dielectric loss ε'') have been investigated. ρdc was found to decrease with temperature for all samples while it increases with increasing Nd3+ concentration. On the other hand, ρac and the dielectric properties were found to decrease with increasing the frequency while ρac increases and both ε' and ε'' decrease with increasing Nd3+ concentration. These results were explained by the Maxwell-Wagner two-layer model and Koops's theory. The improvement in dc and ac electric resistivities shows that these prepared materials are valid for decreasing the eddy current losses at high frequencies, so they can be used in the fabrication of multilayer chip inductor (MLCI) devices.
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NASA Astrophysics Data System (ADS)
Tan, Ting; Yan, Zhimiao; Lei, Hong
2017-07-01
Galloping-based piezoelectric energy harvesters scavenge small-scale wind energy and convert it into electrical energy. For piezoelectric energy harvesting with the same vibrational source (galloping) but different (alternating-current (AC) and direct-current (DC)) interfaces, general analytical solutions of the electromechanical coupled distributed parameter model are proposed. Galloping is theoretically proven to appear when the linear aerodynamic negative damping overcomes the electrical damping and mechanical damping. The harvested power is demonstrated as being done by the electrical damping force. Via tuning the load resistance to its optimal value for optimal or maximal electrical damping, the harvested power of the given structure with the AC/DC interface is maximized. The optimal load resistances and the corresponding performances of such two systems are compared. The optimal electrical damping are the same but with different optimal load resistances for the systems with the AC and DC interfaces. At small wind speeds where the optimal electrical damping can be realized by only tuning the load resistance, the performances of such two energy harvesting systems, including the minimal onset speeds to galloping, maximal harvested powers and corresponding tip displacements are almost the same. Smaller maximal electrical damping with larger optimal load resistance is found for the harvester with the DC interface when compared to those for the harvester with the AC interface. At large wind speeds when the maximal electrical damping rather than the optimal electrical damping can be reached by tuning the load resistance alone, the harvester with the AC interface circuit is recommended for a higher maximal harvested power with a smaller tip displacement. This study provides a method using the general electrical damping to connect and compare the performances of piezoelectric energy harvesters with same excitation source but different interfaces.
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NASA Astrophysics Data System (ADS)
Konishi, Takeshi; Nakamura, Taketsune; Amemiya, Naoyuki
Induction motor instead of dc one has been applied widely for dc electric rolling stock because of the advantage of its utility and efficiency. However, further improvement of motor characteristics will be required to realize environment-friendly dc railway system in the future. It is important to study more efficient machine applying dc electric rolling stock for next generation high performance system. On the other hand, the methods to reuse regenerative energy produced by motors effectively are also important. Therefore, we carried out fundamental study on saving energy for electrified railway system. For the first step, we introduced the energy storage system applying electric double-layer capacitors (EDLC), and its control system. And then, we tried to obtain the specification of high temperature superconductor induction/synchronous motor (HTS-ISM), which performance is similar with that of the conventional induction motors. Furthermore, we tried to evaluate an electrified railway system applying energy storage system and HTS-ISM based on simulation. We succeeded in showing the effectiveness of the introductions of energy storage system and HTS-ISM in DC electrified railway system.
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Lewpiriyawong, Nuttawut; Xu, Guolin; Yang, Chun
2018-03-01
This paper presents the use of DC-biased AC electric field for enhancing cell trapping throughput in an insulator-based dielectrophoretic (iDEP) fluidic device with densely packed silica beads. Cell suspension is carried through the iDEP device by a pressure-driven flow. Under an applied DC-biased AC electric field, DEP trapping force is produced as a result of non-uniform electric field induced by the gap of electrically insulating silica beads packed between two mesh electrodes that allow both fluid and cells to pass through. While the AC component is mainly to control the magnitude of DEP trapping force, the DC component generates local electroosmotic (EO) flow in the cavity between the beads and the EO flow can be set to move along or against the main pressure-driven flow. Our experimental and simulation results show that desirable trapping is achieved when the EO flow direction is along (not against) the main flow direction. Using our proposed DC-biased AC field, the device can enhance the trapping throughput (in terms of the flowrate of cell suspension) up to five times while yielding almost the same cell capture rates as compared to the pure AC field case. Additionally, the device was demonstrated to selectively trap dead yeast cells from a mixture of flowing live and dead yeast cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
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77 FR 31341 - Application To Export Electric Energy; DC Energy, LLC
Federal Register 2010, 2011, 2012, 2013, 2014
2012-05-25
... energy from the United States to Canada as a power marketer for a five-year term. The current export... DC Energy. The application also indicates that DC Energy is a power marketer authorized by the...
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A comparison of in situ measurements of vector-E and - vector-V x vector-B from Dynamics Explorer 2
NASA Technical Reports Server (NTRS)
Hanson, W. B.; Coley, W. R.; Heelis, R. A.; Maynard, N. C.; Aggson, T. L.
1993-01-01
Dynamics Explorer-2 provided the first opportunity to make a direct comparison of in situ measurements of the high-latitude convection electric field by two distinctly different techniques. The vector electric field instrument (VEFI) used antennae to measure the intrinsic electric fields and the ion drift meter (IDM) and retarding potential analyzer (RPA) measured the ion drift velocity vector, from which the convection electric field can be deduced. The data from three orbits having large electric fields at high latitude are presented, one at high, one at medium, and one at low altitudes. The general agreement between the two measurements of electric field is very good, with typical differences at high latitudes of the order of a few millivolts per meter, but there are some regions where the particle fluxes are extremely large (e.g., the cusp) and the disagreement is worse, probably because of IDM difficulties. The auroral zone potential patterns derived from the two devices are in excellent agreement for two of the cases, but not in the third, where bad attitude data may be the problem. At low latitudes there are persistent differences in the measurements of a few millivolts per meter, though these differences are quite constant from orbit to orbit. This problem seems to arise from some shortcoming in the VEFI measurments. Overall, however, these measurements confirm the concept of `frozen-in' plasma that drifts with velocity vector-E x vector-B/B(exp 2) within the measurement errors of the two techniques.
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Fuzzy energy management for hybrid fuel cell/battery systems for more electric aircraft
NASA Astrophysics Data System (ADS)
Corcau, Jenica-Ileana; Dinca, Liviu; Grigorie, Teodor Lucian; Tudosie, Alexandru-Nicolae
2017-06-01
In this paper is presented the simulation and analysis of a Fuzzy Energy Management for Hybrid Fuel cell/Battery Systems used for More Electric Aircraft. The fuel cell hybrid system contains of fuel cell, lithium-ion batteries along with associated dc to dc boost converters. In this configuration the battery has a dc to dc converter, because it is an active in the system. The energy management scheme includes the rule based fuzzy logic strategy. This scheme has a faster response to load change and is more robust to measurement imprecisions. Simulation will be provided using Matlab/Simulink based models. Simulation results are given to show the overall system performance.
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Wang, Lixia; Jiang, Yaoping; Lin, Youhui; Pang, Jie; Liu, Xiang Yang
2016-05-20
Konjac glucomannan-tungsten (KGM-T) hydrogel of electrochemical reversibility was successfully produced under DC electric fields in the presence of sodium tungstate. The structure and the effects of sodium tungstate concentration, KGM concentration, voltage and electric processing time on the rheological properties of the gels were investigated. pH experiments showed that KGM sol containing Na2WO4·2H2O in the vicinity of the positive electrode became acidic and the negative electrode basic after the application of DC electric fields. Under acid conditions, WO4(2-) ions transformed into isopoly-tungstic acid ions. FTIR and Raman studies indicated that isopoly-tungstic acid ions absorbed on KGM molecular chain and cross-linked with -OH groups at C-6 position on sugar units of KGM. Frequency sweep data showed with increasing sodium tungstate concentration, voltage, and electric processing time, the viscoelastic moduli, i.e., the storage and the loss moduli of the gel increased, whereas an increase in KGM concentration led to a decrease in gel viscoelastic moduli. The temperature sweep measurements indicated the obtained gel exhibited high thermal stability. Finally, the mechanism of gel formation was proposed. Our work may pave the way to use DC electric fields for the design and development of KGM gels as well as polysaccharide gels. Copyright © 2016 Elsevier Ltd. All rights reserved.
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Navy/ASEE (American Society for Engineering Education) Summer Faculty Research Program, 1985.
1986-05-15
MECHANICAL ENGINEERING ASTRONOMY MECHANICAL ENGINEERING DEPT. 07 PHYSICS/ASTR. BETHLEHEM ,PA 18015 EAU CLAIR2 ,WI 54701 ROBERT HARTFORD TIMOTHY LANCEY...GA 30910 KLAMATH FALLS ,OR 97601 RICHARD MESSNER HORACE REYNOLDS UN:V OF NEW HAMPSHIRE GALLAUDET ELECTRICAL ENGINEERING PSYCHOLOGY E.C.E. DEPARTMENT...HOWARD’ U:V:ERSICY 4 DC CATHOLU. UNIVERSIT 4 DC HOWARD NVESC 4 DC HOWARD U NIVERSITYf 4 DC CATHOLIT’ UNIVERSITY DC GALLAUDET 4 DC AINERICA:; :;VRIY4 DE
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Grys, Maciej; Madeja, Zbigniew; Korohoda, Włodzimierz
2017-01-01
The harmful side effects of electroporation to cells due to local changes in pH, the appearance of toxic electrode products, temperature increase, and the heterogeneity of the electric field acting on cells in the cuvettes used for electroporation were observed and discussed in several laboratories. If cells are subjected to weak electric fields for prolonged periods, for example in experiments on cell electrophoresis or galvanotaxis the same effects are seen. In these experiments investigators managed to reduce or eliminate the harmful side effects of electric current application. For the experiments, disposable 20 μl cuvettes with two walls made of dialysis membranes were constructed and placed in a locally focused electric field at a considerable distance from the electrodes. Cuvettes were mounted into an apparatus for horizontal electrophoresis and the cells were subjected to direct current electric field (dcEF) pulses from a commercial pulse generator of exponentially declining pulses and from a custom-made generator of double and single rectangular pulses. More than 80% of the electroporated cells survived the dcEF pulses in both systems. Side effects related to electrodes were eliminated in both the flow through the dcEF and in the disposable cuvettes placed in the focused dcEFs. With a disposable cuvette system, we also confirmed the sensitization of cells to a dcEF using procaine by observing the loading of AT2 cells with calceine and using a square pulse generator, applying 50 ms single rectangular pulses. We suggest that the same methods of avoiding the side effects of electric current pulse application as in cell electrophoresis and galvanotaxis should also be used for electroporation. This conclusion was confirmed in our electroporation experiments performed in conditions assuring survival of over 80% of the electroporated cells. If the amplitude, duration, and shape of the dcEF pulse are known, then electroporation does not depend on the type of pulse generator. This knowledge of the characteristics of the pulse assures reproducibility of electroporation experiments using different equipment.
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Bi, Ran; Schlaak, Michael; Siefert, Eike; Lord, Richard; Connolly, Helen
2011-04-01
The combined use of electrokinetic remediation and phytoremediation to decontaminate soil polluted with heavy metals has been demonstrated in a laboratory-scale experiment. The plants species selected were rapeseed and tobacco. Three kinds of soil were used: un-contaminated soil from forest area (S1), artificially contaminated soil with 15mgkg(-1) Cd (S2) and multi-contaminated soil with Cd, Zn and Pb from an industrial area (S3). Three treatment conditions were applied to the plants growing in the experimental vessels: control (no electrical field), alternating current electrical field (AC, 1Vcm(-1)) and direct current electrical field (DC, 1Vcm(-1)) with switching polarity every 3h. The electrical fields were applied for 30d for rapeseed and 90d for tobacco, each experiment had three replicates. After a total of 90d growth for rapeseed and of 180d for tobacco, the plants were harvested. The pH variation from anode to cathode was eliminated by switching the polarity of the DC field. The plants reacted differently under the applied electrical field. Rapeseed biomass was enhanced under the AC field and no negative effect was found under DC field. However, no enhancement of the tobacco biomass under the AC treatment was found. The DC field had a negative influence on biomass production on tobacco plants. In general, Cd content was higher in both species growing in S2 treated with AC field compared to the control. Metal uptake (Cd, Cu, Zn and Pb) per rapeseed plant shoot was enhanced by the application of AC field in all soils. Copyright © 2010 Elsevier Ltd. All rights reserved.
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DC-to-DC power supply for light aircraft flight testing
NASA Technical Reports Server (NTRS)
Yost, S. R.
1980-01-01
The power supply unit was developed to serve as the power source for a loran-C receiver. The power supply can be connected directly to the aircraft's electrical system, and is compatible with either 14 or 28 volt electrical systems. Design specifications are presented for the unit along with a description of the circuit design.
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ERIC Educational Resources Information Center
Silva-Ortigoza, R.; Silva-Ortigoza, G.; Hernandez-Guzman, V. M.; Saldana-Gonzalez, G.; Marcelino-Aranda, M.; Marciano-Melchor, M.
2012-01-01
We introduce a dc/dc boost power converter as a didactic prototype intended to support courses on electric circuit analysis experimentally. The corresponding mathematical model is obtained, the converter is designed and an experimental setup is described, constructed and tested. Simplicity of construction as well as low cost of components renders…
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Garbesi, Karina; Vossos, Vagelis; Sanstad, Alan
An increasing number of energy efficient appliances operate on direct current (DC) internally, offering the potential to use DC from renewable energy systems directly and avoiding the losses inherent in converting power to alternating current (AC) and back. This paper investigates that potential for net-metered residences with on-site photovoltaics (PV) by modeling the net power draw of the ‘direct-DC house’ with respect to today’s typical configuration, assuming identical DC-internal loads. Power draws were modeled for houses in 14 U.S. cities, using hourly, simulated PV-system output and residential loads. The latter were adjusted to reflect a 33% load reduction, representative ofmore » the most efficient DC-internal technology, based on an analysis of 32 electricity end-uses. The model tested the effect of climate, electric vehicle (EV) loads, electricity storage, and load shifting on electricity savings; a sensitivity analysis was conducted to determine how future changes in the efficiencies of power system components might affect savings potential. Based on this work, we estimate that net-metered PV residences could save 5% of their total electricity load for houses without storage and 14% for houses with storage. Based on residential PV penetration projections for year 2035 obtained from the National Energy Modeling System (2.7% for the reference case and 11.2% for the extended policy case), direct-DC could save the nation 10 trillion Btu (without storage) or 40 trillion Btu (with storage). Shifting the cooling load by two hours earlier in the day (pre-cooling) has negligible benefits for energy savings. Direct-DC provides no energy savings benefits for EV charging, to the extent that charging occurs at night. However, if charging occurred during the day, for example with employees charging while at work, the benefits would be large. Direct-DC energy savings are sensitive to power system and appliance conversion efficiencies but are not significantly influenced by climate. While direct-DC for residential applications will most likely arise as a spin-off of developments in the commercial sector—because of lower barriers to market entry and larger energy benefits resulting from the higher coincidence between load and insolation—this paper demonstrates that there are substantial benefits in the residential sector as well. Among residential applications, space cooling derives the largest energy savings from being delivered by a direct-DC system. It is the largest load for the average residence on a national basis and is particularly so in high-load regions. It is also the load with highest solar coincidence.« less
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Direct current electrical potential measurement of the growth of small cracks
NASA Technical Reports Server (NTRS)
Gangloff, Richard P.; Slavik, Donald C.; Piascik, Robert S.; Van Stone, Robert H.
1992-01-01
The analytical and experimental aspects of the direct-current electrical potential difference (dcEPD) method for continuous monitoring of the growth kinetics of short (50 to 500 microns) fatigue cracks are reviewed, and successful applications of the deEPD method to study fatigue crack propagation in a variety of metallic alloys exposed to various environments are described. Particular attention is given to the principle of the dcEPD method, the analytical electrical potential calibration relationships, and the experimental procedures and equipment.
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NASA Technical Reports Server (NTRS)
Bifano, W. J.; Ratajczak, A. F.; Ice, W. J.
1978-01-01
A stand alone photovoltaic power system for installation in the Papago Indian village of Schuchuli is being designed and fabricated to provide electricity for village water pumping and basic domestic needs. The system will consist of a 3.5 kW (peak) photovoltaic array; controls, instrumentations, and storage batteries located in an electrical equipment building and a 120 volt dc village distribution network. The system will power a 2 HP dc electric motor.
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Lu, Bin; Harley, Ronald G.; Du, Liang; Yang, Yi; Sharma, Santosh K.; Zambare, Prachi; Madane, Mayura A.
2014-06-17
A method identifies electric load types of a plurality of different electric loads. The method includes providing a self-organizing map load feature database of a plurality of different electric load types and a plurality of neurons, each of the load types corresponding to a number of the neurons; employing a weight vector for each of the neurons; sensing a voltage signal and a current signal for each of the loads; determining a load feature vector including at least four different load features from the sensed voltage signal and the sensed current signal for a corresponding one of the loads; and identifying by a processor one of the load types by relating the load feature vector to the neurons of the database by identifying the weight vector of one of the neurons corresponding to the one of the load types that is a minimal distance to the load feature vector.
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EVA Metro Sedan electric-propulsion system: test and evaluation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Reimers, E.
1979-09-01
The procedure and results of the performance evaluation of the EVA Metro Sedan (car No. 1) variable speed dc chopper motor drive and its three speed automatic transmission are presented. The propulsion system for a battery powered vehicle manufactured by Electric Vehicle Associates, Valley View, Ohio, was removed from the vehicle, mounted on the programmable electric dynamometer test facility and evaluated with the aid of a hp 3052A Data Acquisition System. Performance data for the automatic transmission, the solid state dc motor speed controller, and the dc motor in the continuous and pulsating dc power mode, as derived on themore » dynamometer test facility, as well as the entire propulsion system are given. This concept and the system's components were evaluated in terms of commercial applicability, maintainability, and energy utility to establish a design base for the further development of this system or similar propulsion drives. The propulsion system of the EVA Metro Sedan is powered by sixteen 6-volt traction batteries, Type EV 106 (Exide Battery Mfg. Co.). A thyristor controlled cable form Pulsomatic Mark 10 controller, actuated by a foot throttle, controls the voltage applied to a dc series field motor, rated at 10 hp at 3800 rpm (Baldor Electric Co.). Gear speed reduction to the wheel is accomplished by the original equipment three speed automatic transmission with torque converter (Renault 12 Sedan). The brake consists of a power-assisted, hydraulic braking system with front wheel disk and rear drum. An ability to recuperate electric energy with subsequent storage in the battery power supply is not provided.« less
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NASA Astrophysics Data System (ADS)
Wei, Y. W.; Liu, G. T.; Xiong, S. N.; Cheng, J. Z.; Huang, Y. H.
2017-01-01
In the near future, electric vehicle is entirely possible to replace traditional cars due to its zero pollution, small power consumption and low noise. Lithium-ion battery, which owns lots of advantages such as lighter and larger capacity and longer life, has been widely equipped in different electric cars all over the world. One disadvantage of this energy storage device is state of charge (SOC) difference among these cells in each series branch. If equalization circuit is not allocated for series-connected batteries, its safety and lifetime are declined due to over-charge or over-discharge happened, unavoidably. In this paper, a novel modularized equalization circuit, based on DC-DC chopper, is proposed to supply zero loss in theory. The proposed circuit works as an equalizer when Lithium-ion battery pack is charging or discharging or standing idle. Theoretical analysis and control method have been finished, respectively. Simulation and small scale experiments are applied to verify its real effect.
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NASA Astrophysics Data System (ADS)
Jacquot, Jonathan; Tierens, Wouter; Zhang, Wei; Bobkov, Volodymyr; Colas, Laurent; Noterdaeme, Jean-Marie
2017-10-01
A sequence of simulations is performed with RAPLICASOL and SSWICH to compare two AUG ICRF antennas. RAPLICASOL outputs have been used as input to SSWICH-SW for the AUG ICRF antennas. Using parallel electric field maps and the scattering matrix produced by RAPLICASOL, SSWICH-SW, reduced to its asymptotic part, is able to produce a 2D radial/poloidal map of the DC plasma potential accounting for the antenna input settings (total power, power balance, phasing). Two models of antennas are compared: 2-strap antenna vs 3-strap antenna. The 2D DC potential structures are correlated to structures of the parallel electric field map for different phasing and power balance. The overall DC plasma potential on the 3-strap antenna is lower due to better global RF currents compensation. Spatial proximity between regions of high RF electric field and regions where high DC plasma potentials are observed is an important factor for sheath rectification.
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Power processing units for high power solar electric propulsion
NASA Astrophysics Data System (ADS)
Frisbee, Robert H.; Das, Radhe S.; Krauthamer, Stanley
An evaluation of high-power processing units (PPUs) for multimegawatt solar electric propulsion (SEP) vehicles using advanced ion thrusters is presented. Significant savings of scale are possible for PPUs used to supply power to ion thrusters operating at 0.1 to 1.5 MWe per thruster. The PPU specific mass is found to be strongly sensitive to variations in the ion thruster's power per thruster and moderately sensitive to variations in the thruster's screen voltage due to varying the I(sp) of the thruster. Each PPU consists of a dc-to-dc converter to increase the voltage from the 500 V dc of the photovoltaic power system to the 5 to 13 kV dc required by the ion thrusters.
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Electrical properties of binary mixtures of amino silicone oil and methyl iso butyl ketone
NASA Astrophysics Data System (ADS)
Shah, K. N.; Rana, V. A.; Vankar, H. P.
2018-05-01
The real and imaginary parts of the dielectric function of the binary mixtures of the methyl iso butyl ketone and amino silicone oil in the frequency range 100 Hz to 2 MHz were measured using precision LCR meter at 305.15 K. The electrical properties such as electrical modulus M*(ω), electrical conductivity σ*(ω) and complex impedance Z*(ω) were calculated using the dielectric function ɛ*(ω). The ionic polarization relaxation time (Τσ) and D.C. conductivity (σdc) were also calculated using electrical properties. The ionic behavior of methyl iso butyl ketone and non-ionic behavior of amino silicone oil are also explained. The electrical parameters are used to gain information about the effect of concentration variation of components of the mixtures on the electrical properties.
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Experimental study of a fuel cell power train for road transport application
NASA Astrophysics Data System (ADS)
Corbo, P.; Corcione, F. E.; Migliardini, F.; Veneri, O.
The development of fuel cell electric vehicles requires the on-board integration of fuel cell systems and electric energy storage devices, with an appropriate energy management system. The optimization of performance and efficiency needs an experimental analysis of the power train, which has to be effected in both stationary and transient conditions (including standard driving cycles). In this paper experimental results concerning the performance of a fuel cell power train are reported and discussed. In particular characterization results for a small sized fuel cell system (FCS), based on a 2.5 kW PEM stack, alone and coupled to an electric propulsion chain of 3.7 kW are presented and discussed. The control unit of the FCS allowed the main stack operative parameters (stoichiometric ratio, hydrogen and air pressure, temperature) to be varied and regulated in order to obtain optimized polarization and efficiency curves. Experimental runs effected on the power train during standard driving cycles have allowed the performance and efficiency of the individual components (fuel cell stack and auxiliaries, dc-dc converter, traction batteries, electric engine) to be evaluated, evidencing the role of output current and voltage of the dc-dc converter in directing the energy flows within the propulsion system.
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NASA Astrophysics Data System (ADS)
Zhao, Pengcheng; Guo, Lixin; Shu, Panpan
2016-08-01
The gas breakdown induced by a square microwave pulse with a crossed dc magnetic field is investigated using the electron fluid model, in which the accurate electron energy distribution functions are adopted. Simulation results show that at low gas pressures the dc magnetic field of a few tenths of a tesla can prolong the breakdown formation time by reducing the mean electron energy. With the gas pressure increasing, the higher dc magnetic field is required to suppress the microwave breakdown. The electric field along the microwave propagation direction generated due to the motion of electrons obviously increases with the dc magnetic field, but it is much less than the incident electric field. The breakdown predictions of the electron fluid model agree very well with the particle-in-cell-Monte Carlo collision simulations as well as the scaling law for the microwave gas breakdown.
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High Voltage Design Concepts for Launch Vehicles and Orbital Spacecraft Applications
NASA Technical Reports Server (NTRS)
Hall, David K.; Kirkici, Hulya; Hillard, G. Barry; Schweickart, Daniel; Dunbar, Bill
2000-01-01
With the advent of design concepts such as, electromechanical actuation and "more electric" initiatives, has come the need for electrical power buses and electronic equipment to operate at higher than normal dc voltages to meet power requirements while keeping current levels to manageable levels. This new bus voltage has been typically 270 Volts dc nominal for launch vehicles, and 120 Volt dc for the International Space Station. This paper will discuss the new design applications for high voltage dc power in existing and future launch vehicles and spacecraft and the potential problems associated therewith. These new applications must be operational from lift-off, ascent, on orbit and descent in all of the pressure and temperature conditions for each, i.e. through the "Paschen region" twice. This paper will also attempt to stimulate an interest in the academic and professional communities to support and conduct research needed for design data applicable to high voltage dc usage.
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A New Integrated Onboard Charger and Accessory Power Converter for Plug-in Electric Vehicles
DOE Office of Scientific and Technical Information (OSTI.GOV)
Su, Gui-Jia; Tang, Lixin
2014-01-01
In this paper, a new approach is presented for integrating the function of onboard battery charging into the traction drive system and accessory dc-dc converter of a plug-in electric vehicle (PEV). The idea is to utilize the segmented traction drive system of a PEV as the frond converter of the charging circuit and the transformer and high voltage converter of the 14 V accessory dc-dc converter to form a galvanically isolated onboard charger. Moreover, a control method is presented for suppressing the battery current ripple component of twice the grid frequency with the reduced dc bus capacitor in the segmentedmore » inverter. The resultant integrated charger has lower cost, weight, and volume than a standalone charger due to a substantially reduced component count. The proposed integrated charger topology was verified by modeling and experimental results on a 5.8 kW charger prototype.« less
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Kim, Min Sung; Lee, Mi Hee; Kwon, Byeong-Ju; Koo, Min-Ah; Seon, Gyeung Mi; Park, Jong-Chul
2015-05-01
Directional cell migration requires cell polarization. The reorganization of the Golgi apparatus is an important phenomenon in the polarization and migration of many types of cells. Direct current electric fields (dc (EF) induced directional cell migration in a wide variety of cells. Here nHDFs migrated toward cathode under 1 V/cm dc EF, however 1 μM of brefeldin A (BFA) inhibited the dc EF induced directional migration. BFA (1 μM) did not cause the complete Golgi dispersal for 2 h. When the Golgi polarization maintained their direction of polarity, the direction of cell migration also kept toward the same direction of the Golgi polarization even though the dc EF was reversed. In this study, the importance of the Golgi polarization in the directional migration of nHDf under dc EF was identified. Copyright © 2015 Elsevier Inc. All rights reserved.
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NASA Astrophysics Data System (ADS)
Kanai, Shun; Gajek, Martin; Worledge, D. C.; Matsukura, Fumihiro; Ohno, Hideo
2014-12-01
We measure homodyne-detected ferromagnetic resonance (FMR) induced by the electric-field effect in a CoFeB/MgO/CoFeB magnetic tunnel junction (MTJ) with perpendicular magnetic easy axis under dc bias voltages up to 0.1 V. From the bias dependence of the resonant frequency, we find that the first order perpendicular magnetic anisotropy is modulated by the applied electric field, whereas the second order component is virtually independent of the electric field. The lineshapes of the FMR spectra are bias dependent, which are explained by the combination of electric-field effect and reflection of the bias voltage from the MTJ.
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NASA Astrophysics Data System (ADS)
Matveev, O. P.; Shvaika, A. M.; Devereaux, T. P.; Freericks, J. K.
2016-01-01
Using the Kadanoff-Baym-Keldysh formalism, we employ nonequilibrium dynamical mean-field theory to exactly solve for the nonlinear response of an electron-mediated charge-density-wave-ordered material. We examine both the dc current and the order parameter of the conduction electrons as the ordered system is driven by the electric field. Although the formalism we develop applies to all models, for concreteness, we examine the charge-density-wave phase of the Falicov-Kimball model, which displays a number of anomalous behaviors including the appearance of subgap density of states as the temperature increases. These subgap states should have a significant impact on transport properties, particularly the nonlinear response of the system to a large dc electric field.
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Experimental Study of a Pack of Supercapacitors Used in Electric Vehicles.
Mansour, Amari; Mohamed Hedi, Chabchoub; Faouzi, Bacha
2017-01-01
Electric vehicles have recently attracted research interest. An electric vehicle is composed of two energy sources, such as fuel cells and ultracapacitors, which are employed to provide, respectively, the steady-state and transient power demanded by the vehicle. A bidirectional DC-DC converter is needed to interface the ultracapacitor to a DC bus. The pack of ultracapacitor consists of many cells in series and possibly also in parallel. In this regard, this paper introduces a comparative study between two packs of supercapacitors. The first supercapacitor pack is composed of ten cells in series but the second supercapacitor pack is composed of five cells in series and two parallel circuits. Each cell is characterized by 2.5 V and 100 F. A number of practical tests are presented.
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Experimental Study of a Pack of Supercapacitors Used in Electric Vehicles
Mohamed Hedi, Chabchoub
2017-01-01
Electric vehicles have recently attracted research interest. An electric vehicle is composed of two energy sources, such as fuel cells and ultracapacitors, which are employed to provide, respectively, the steady-state and transient power demanded by the vehicle. A bidirectional DC-DC converter is needed to interface the ultracapacitor to a DC bus. The pack of ultracapacitor consists of many cells in series and possibly also in parallel. In this regard, this paper introduces a comparative study between two packs of supercapacitors. The first supercapacitor pack is composed of ten cells in series but the second supercapacitor pack is composed of five cells in series and two parallel circuits. Each cell is characterized by 2.5 V and 100 F. A number of practical tests are presented. PMID:28894785
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The nuclear electric quadrupole moment of antimony from the molecular method.
Haiduke, Roberto L A; da Silva, Albérico B F; Visscher, Lucas
2006-08-14
Relativistic Dirac-Coulomb (DC) Hartree-Fock calculations are employed to obtain the analytic electric field gradient (EFG) on the antimony nucleus in the SbN, SbP, SbF, and SbCl molecules. The electronic correlation contribution to the EFGs is included with the DC-CCSD(T) and DC-CCSD-T approaches, also in the four-component framework, using a finite-difference method. The total EFG results, along with the experimental nuclear quadrupole coupling constants from microwave spectroscopy, allow to derive the nuclear quadrupole moments of (121)Sb and (123)Sb, respectively, as -543(11) and -692(14) mb.
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NASA Astrophysics Data System (ADS)
Zuo, Xiao; Chen, Rende; Liu, Jingzhou; Ke, Peiling; Wang, Aiying
2018-01-01
The electrical characteristics and spectroscopic properties have been comprehensively investigated in a DC superimposed high power impulse magnetron sputtering (DC-HiPIMS) deposition system in this paper. The influence of superimposed DC current on the variation of target and substrate current waveforms, active species and electron temperatures with pulse voltages are focused. The peak target currents in DC-HiPIMS are lower than in HiPIMS. The time scales of the two main discharge processes like ionization and gas rarefaction in DC-HiPIMS are analyzed. When the pulse voltage is higher than 600 V, the gas rarefaction effect becomes apparent. Overall, the ionization process is found to be dominant in the initial ˜100 μs during each pulse. The active species of Ar and Cr in DC-HiPIMS are higher than in HiPIMS unless that the pulse voltage reaches 900 V. However, the ionization degree in HiPIMS exceeds that in DC-HiPIMS at around 600 V. The electron temperature calculated by modified Boltzmann plot method based on corona model has a precipitous increase from 0.87 to 25.0 eV in HiPIMS, but varies mildly after the introduction of the superimposed DC current. Additionally, the current from plasma flowing to the substrate is improved when a DC current is superimposed with HiPIMS.
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Multiple piezo-patch energy harvesters on a thin plate with respective AC-DC conversion
NASA Astrophysics Data System (ADS)
Aghakhani, Amirreza; Basdogan, Ipek
2018-03-01
Piezoelectric patch energy harvesters can be directly integrated to plate-like structures which are widely used in automotive, marine and aerospace applications, to convert vibrational energy to electrical energy. This paper presents two different AC-DC conversion techniques for multiple patch harvesters, namely single rectifier and respective rectifiers. The first case considers all the piezo-patches are connected in parallel to a single rectifier, whereas in the second case, each harvester is respectively rectified and then connected in parallel to a smoothing capacitor and a resistive load. The latter configuration of AC-DC conversion helps to avoid the electrical charge cancellation which is a problem with the multiple harvesters attached to different locations of the host plate surface. Equivalent circuit model of the multiple piezo-patch harvesters is developed in the SPICE software to simulate the electrical response. The system parameters are obtained from the modal analysis solution of the plate. Simulations of the voltage frequency response functions (FRFs) for the standard AC input - AC output case are conducted and validated by experimental data. Finally, for the AC input - DC output case, numerical simulation and experimental results of the power outputs of multiple piezo-patch harvesters with multiple AC-DC converters are obtained for a wide range of resistive loads and compared with the same array of harvesters connected to a single AC-DC converter.
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Bikson, Marom; Inoue, Masashi; Akiyama, Hiroki; Deans, Jackie K; Fox, John E; Miyakawa, Hiroyoshi; Jefferys, John G R
2004-05-15
The effects of uniform steady state (DC) extracellular electric fields on neuronal excitability were characterized in rat hippocampal slices using field, intracellular and voltage-sensitive dye recordings. Small electric fields (1 s) changes in neuronal excitability. Electric fields perpendicular to the apical-dendritic axis did not induce somatic polarization, but did modulate orthodromic responses, indicating an effect on afferents. These results demonstrate that DC fields can modulate neuronal excitability in a time-dependent manner, with no clear threshold, as a result of interactions between neuronal compartments, the non-linear properties of the cell membrane, and effects on afferents.
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Recovery of consciousness in broilers following combined dc and ac stunning
USDA-ARS?s Scientific Manuscript database
Broilers in the United States are typically electrically stunned using low voltage-high frequency pulsed DC water bath stunners and in the European Union broilers are electrocuted using high voltage-low frequency AC. DC stunned broilers regain consciousness in the absence of exsanguination and AC st...
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Terahertz-Frequency Spin Hall Auto-oscillator Based on a Canted Antiferromagnet
NASA Astrophysics Data System (ADS)
Sulymenko, O. R.; Prokopenko, O. V.; Tiberkevich, V. S.; Slavin, A. N.; Ivanov, B. A.; Khymyn, R. S.
2017-12-01
We propose a design of a terahertz-frequency signal generator based on a layered structure consisting of a current-driven platinum (Pt) layer and a layer of an antiferromagnet (AFM) with easy-plane anisotropy, where the magnetization vectors of the AFM sublattices are canted inside the easy plane by the Dzyaloshinskii-Moriya interaction (DMI). The dc electric current flowing in the Pt layer creates due to the spin Hall effect, a perpendicular spin current that, being injected in the AFM layer, tilts the DMI-canted AFM sublattices out of the easy plane, thus exposing them to the action of a strong internal exchange magnetic field of the AFM. The sublattice magnetizations, along with the small net magnetization vector mDMI of the canted AFM, start to rotate about the hard anisotropy axis of the AFM with the terahertz frequency proportional to the injected spin current and the AFM exchange field. The rotation of the small net magnetization mDMI results in the terahertz-frequency dipolar radiation that can be directly received by an adjacent (e.g., dielectric) resonator. We demonstrate theoretically that the radiation frequencies in the range f =0.05 - 2 THz are possible at the experimentally reachable magnitudes of the driving current density, and we evaluate the power of the signal radiated into different types of resonators. This power increases with the increase of frequency f , and it can exceed 1 μ W at f ˜0.5 THz for a typical dielectric resonator of the electric permittivity ɛ ˜10 and a quality factor Q ˜750 .
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Document for 270 Voltage Direct Current (270 V dc) System
NASA Astrophysics Data System (ADS)
1992-09-01
The paper presents the technical design and application information established by the SAE Aerospace Recommended Practice concerning the generation, distribution, control, and utilization of aircraft 270 V dc electrical power systems and support equipment. Also presented are references and definitions making it possible to compare various electrical systems and components. A diagram of the generic 270 V Direct Current High-Voltage Direct System is included.
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Vector optical fields with polarization distributions similar to electric and magnetic field lines.
Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian
2013-07-01
We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations of "electric charges" and "magnetic charges" can engineer the spatial structure and symmetry of polarizations of vector optical field, providing additional degrees of freedom assisting in controlling the field symmetry at the focus and allowing engineering of the field distribution at the focus to the specific applications.
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NASA Technical Reports Server (NTRS)
Neudeck, Philip G.; Huang, Wei; Dudley, Michael
1998-01-01
Given the high density (approx. 10(exp 4)/sq cm) of elementary screw dislocations (Burgers vector = 1c with no hollow core) in commercial SiC wafers and epilayers, all appreciable current (greater than 1 A) SiC power devices will likely contain elementary screw dislocations for the foreseeable future. It is therefore important to ascertain the electrical impact of these defects, particularly in high-field vertical power device topologies where SiC is expected to enable large performance improvements in solid-state high-power systems. This paper compares the DC-measured reverse-breakdown characteristics of low-voltage (less than 250 V) small-area (less than 5 x 10(exp -4)/sq cm) 4H-SiC p(+)n diodes with and without elementary screw dislocations. Compared to screw dislocation-free devices, diodes containing elementary screw dislocations exhibited higher pre-breakdown reverse leakage currents, softer reverse breakdown I-V knees, and highly localized microplasmic breakdown current filaments. The observed localized 4H-SiC breakdown parallels microplasmic breakdowns observed in silicon and other semiconductors, in which space-charge effects limit current conduction through the local microplasma as reverse bias is increased.
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NASA Technical Reports Server (NTRS)
Neudeck, Philip G.; Huang, Wei; Dudley, Michael
1999-01-01
Given the high density (approx. 10(exp 4)/sq cm) of elementary screw dislocations (Burgers vector = lc with no hollow core) in commercial SiC wafers and epilayers, all appreciable current (greater than 1 A) SiC power devices will likely contain elementary screw dislocations for the foreseeable future. It is therefore important to ascertain the electrical impact of these defects, particularly in high-field vertical power device topologies where SiC is expected to enable large performance improvements in solid-state high-power systems. This paper compares the DC-measured reverse-breakdown characteristics of low-voltage (less than 250 V) small-area (less than 5 x 10(exp -4) sq cm) 4H-SiC p(+)n diodes with and without elementary screw dislocations. Compared to screw dislocation-free devices, diodes containing elementary screw dislocations exhibited higher pre-breakdown reverse leakage currents, softer reverse breakdown I-V knees, and highly localized microplasmic breakdown current filaments. The observed localized 4H-SiC breakdown parallels microplasmic breakdowns observed in silicon and other semiconductors, in which space-charge effects limit current conduction through the local microplasma as reverse bias is increased.
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NASA Astrophysics Data System (ADS)
Min, Sun-Hong; Kwon, Ohjoon; Sattorov, Matlabjon; Baek, In-Keun; Kim, Seontae; Jeong, Jin-Young; Hong, Dongpyo; Park, Seunghyuk; Park, Gun-Sik
2017-01-01
Non-thermal irreversible electroporation (NTIRE) to avoid thermal damage to cells during intense DC ns pulsed electric fields (nsPEFs) is a recent modality for medical applications. This mechanism, related to bioelectrical dynamics of the cell, is linked to the effect of a DC electric field and a threshold effect with an electrically stimulated membrane for the charge distribution in the cell. To create the NTIRE condition, the pulse width of the nsPEF should be shorter than the charging time constant of the membrane related to the cell radius, membrane capacitance, cytoplasm resistivity, and medium resistivity. It is necessary to design and fabricate a very intense nanosecond DC electric field pulser that is capable of producing voltages up to the level of 100 kV/cm with an artificial pulse width (˜ns) with controllable repetition rates. Many devices to generate intense DC nsPEF using various pulse-forming line technologies have been introduced thus far. However, the previous Blumlein pulse-generating devices are clearly inefficient due to the energy loss between the input voltage and the output voltage. An improved two-stage stacked Blumlein pulse-forming line can overcome this limitation and decrease the energy loss from a DC power supply. A metal oxide silicon field-effect transistor switch with a fast rise and fall time would enable a high repetition rate (max. 100 kHz) and good endurance against very high voltages (DC ˜ 30 kV). The load is designed to match the sample for exposure to cell suspensions consisting of a 200 Ω resistor matched with a Blumlein circuit and two electrodes without the characteristic RC time effect of the circuit (capacitance =0.174 pF).
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Equivalent magnetic vector potential model for low-frequency magnetic exposure assessment
NASA Astrophysics Data System (ADS)
Diao, Y. L.; Sun, W. N.; He, Y. Q.; Leung, S. W.; Siu, Y. M.
2017-10-01
In this paper, a novel source model based on a magnetic vector potential for the assessment of induced electric field strength in a human body exposed to the low-frequency (LF) magnetic field of an electrical appliance is presented. The construction of the vector potential model requires only a single-component magnetic field to be measured close to the appliance under test, hence relieving considerable practical measurement effort—the radial basis functions (RBFs) are adopted for the interpolation of discrete measurements; the magnetic vector potential model can then be directly constructed by summing a set of simple algebraic functions of RBF parameters. The vector potentials are then incorporated into numerical calculations as the equivalent source for evaluations of the induced electric field in the human body model. The accuracy and effectiveness of the proposed model are demonstrated by comparing the induced electric field in a human model to that of the full-wave simulation. This study presents a simple and effective approach for modelling the LF magnetic source. The result of this study could simplify the compliance test procedure for assessing an electrical appliance regarding LF magnetic exposure.
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Equivalent magnetic vector potential model for low-frequency magnetic exposure assessment.
Diao, Y L; Sun, W N; He, Y Q; Leung, S W; Siu, Y M
2017-09-21
In this paper, a novel source model based on a magnetic vector potential for the assessment of induced electric field strength in a human body exposed to the low-frequency (LF) magnetic field of an electrical appliance is presented. The construction of the vector potential model requires only a single-component magnetic field to be measured close to the appliance under test, hence relieving considerable practical measurement effort-the radial basis functions (RBFs) are adopted for the interpolation of discrete measurements; the magnetic vector potential model can then be directly constructed by summing a set of simple algebraic functions of RBF parameters. The vector potentials are then incorporated into numerical calculations as the equivalent source for evaluations of the induced electric field in the human body model. The accuracy and effectiveness of the proposed model are demonstrated by comparing the induced electric field in a human model to that of the full-wave simulation. This study presents a simple and effective approach for modelling the LF magnetic source. The result of this study could simplify the compliance test procedure for assessing an electrical appliance regarding LF magnetic exposure.
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NASA Technical Reports Server (NTRS)
Angel, Paul W.; Hann, Raiford E.; Cooper, Alfred R.
1993-01-01
Electrical response measurements from 10 Hz to 100 kHz between 120 and 540 C were made on potassium-silicate glasses with alkali oxide contents of 2, 3, 5 and 10 mol percent. Low alkali content glasses were chosen in order to try to reduce the Coulombic interactions between alkali ions to the point that frozen structural effects from the glass could be observed. Conductivity and electrical relaxation responses for both annealed and quenched glasses of the same composition were compared. Lower DC conductivity (sigma(sub DC)) activation energies were measured for the quenched compared to the annealed glasses. The two glasses with the lowest alkali contents exhibited a non-Arrhenius concave up curvature in the log(sigma(sub DC)) against 1/T plots, which decreased upon quenching. A sharp decrease in sigma(sub DC) was observed for glasses containing K2O concentrations of 5 mol percent or less. The log modulus loss peak (M'') maximum frequency plots against 1/T all showed Arrhenius behavior for both annealed and quenched samples. The activation energies for these plots closely agreed with the sigma(sub DC) activation energies. A sharp increase in activation energy was observed for both series as the potassium oxide concentration decreased. Changes in the electrical response are attributed to structural effects due to different alkali concentrations. Differences between the annealed and quenched response are linked to a change in the distribution of activation energies (DAE).
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Yang, Fei; Zhang, Tong; Tiwari, Vinod; Shu, Bin; Zhang, Chen; Wang, Yun; Vera-Portocarrero, Louis P.; Raja, Srinivasa N.; Guan, Yun
2015-01-01
Objectives Electrical stimulation at the dorsal column (DC) and dorsal root (DR) may inhibit spinal wide-dynamic-range (WDR) neuronal activity in nerve-injured rats. The objective of this study was to determine if applying electrical conditioning stimulation (CS) at both sites provides additive or synergistic benefits. Materials and Methods By conducting in vivo extracellular recordings of WDR neurons in rats that had undergone L5 spinal nerve ligation, we tested whether combining 50 Hz CS at the two sites in either a concurrent (2.5 minutes) or alternate (5 minutes) pattern inhibits WDR neuronal activity better than CS at DC alone (5 minutes). The intensities of CS were determined by recording antidromic compound action potentials to graded stimulation at the DC and DR. We measured the current thresholds that resulted in the first detectable Aα/β waveform (Ab0) and the peak Aα/β waveform (Ab1) to select CS intensity at each site. The same number of electrical pulses and amount of current were delivered in different patterns to allow comparison. Results At a moderate intensity of 50%(Ab0+Ab1), different patterns of CS all attenuated the C-component of WDR neurons in response to graded intracutaneous electrical stimuli (0.1-10 mA, 2 ms), and inhibited windup in response to repetitive noxious stimuli (0.5 Hz). However, the inhibitory effects did not differ significantly between different patterns. At the lower intensity (Ab0), no CS inhibited WDR neurons. Conclusions These findings suggest that combined stimulation of DC and DR may not be superior to DC stimulation alone for inhibition of WDR neurons. PMID:26307526
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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.
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Schottky-type grain boundaries in CCTO ceramics
NASA Astrophysics Data System (ADS)
Felix, A. A.; Orlandi, M. O.; Varela, J. A.
2011-10-01
In this work we studied electrical barriers existing at CaCu 3Ti 4O 12 (CCTO) ceramics using dc electrical measurements. CCTO pellets were produced by solid state reaction method and X-ray diffractograms showed which single phase polycrystalline samples were obtained. The samples were electrically characterized by dc and ac measurements as a function of temperature, and semiconductor theory was applied to analyze the barrier at grain boundaries. The ac results showed the sample's permittivity is almost constant ( 104) as function of temperature at low frequencies and it changes from 100 to 104 as the temperature increases at high frequencies. Using dc measurements as a function of temperature, the behavior of barriers was studied in detail. Comparison between Schottky and Poole-Frenkel models was performed, and results prove that CCTO barriers are more influenced by temperature than by electric field (Schottky barriers). Besides, the behavior of barrier width as function of temperature was also studied and experimental results confirm the theoretical assumptions.
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NASA Astrophysics Data System (ADS)
Kumagai, Daisuke; Ohsaki, Hiroyuki; Tomita, Masaru
2016-12-01
A superconducting power cable has merits of a high power transmission capacity, transmission losses reduction, a compactness, etc., therefore, we have been studying the feasibility of applying superconducting power cables to DC electric railway feeding systems. However, a superconducting power cable is required to be cooled down and kept at a very low temperature, so it is important to reveal its thermal and cooling characteristics. In this study, electric circuit analysis models of the system and thermal analysis models of superconducting cables were constructed and the system behaviors were simulated. We analyzed the heat generation by a short circuit accident and transient temperature distribution of the cable to estimate the value of temperature rise and the time required from the accident. From these results, we discussed a feasibility of superconducting cables for DC electric railway feeding systems. The results showed that the short circuit accident had little impact on the thermal condition of a superconducting cable in the installed system.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Bharathi, M. N.; Vinayakprasanna, N. H.; Prakash, A. P. Gnana, E-mail: gnanaprakash@physics.uni-mysore.ac.in
The total dose effects of 80 MeV C{sup 6+} ions on the DC electrical characteristics of Silicon NPN rf power transistors have been studied in the dose range of 100 krad to 100 Mrad. The SRIM simulation was used to understand the energy loss and range of the ions in the transistor structure. The different electrical parameters such as Gummel characteristics, excess base current (ΔI{sub B} = I{sub Bpost} - I{sub Bpre}), dc forward current gain (h{sub FE}), transconductance (g{sub m}), displacement damage factor (K) and output characteristics (V{sub CE}-I{sub C}) were studied systematically before and after irradiation. The significantmore » degradation in base current (I{sub B}) and h{sub FE} was observed after irradiation. Isochronal annealing study was conducted on the irradiated transistors to analyze the recovery in different electrical parameters. These results were compared with {sup 60}C0 gamma irradiation results in the same dose range.« less
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Jenrow, K.A.; Smith, C.H.; Liboff, A.R.
1996-12-31
The authors recently reported that cephalic regeneration in the planarian Dugesia tigrina was significantly delayed in populations exposed continuously to combined parallel DC and AC magnetic fields. This effect was consistent with hypotheses suggesting an underlying resonance phenomenon. The authors report here, in a parallel series of investigations on the same model system, that the incidence of regeneration anomalies presenting as tumor-like protuberances also increases significantly (P < .001) in association with exposure to weak 60 Hz magnetic fields, with peak intensities ranging between 1.0 and 80.0 {micro}T. These anomalies often culminate in the complete disaggregation of the organism. Similarmore » to regeneration rate effects, the incidence of regeneration anomalies is specifically dependent upon the planaria possessing a fixed orientation with respect to the applied magnetic field vectors. However, unlike the regeneration rate effects, the AC magnetic field alone, in the absence of any measurable DC field, is capable of producing these anomalies. Moreover, the incidence of regeneration anomalies follows a clear dose-response relationship as a function of AC magnetic field intensity, with the threshold for induced electric field intensity estimated at 5 {micro} V/m. The addition of either 51.1 or 78.4 {micro}T DC magnetic fields, applied in parallel combination with the AC field, enhances the appearance of anomalies relative to the 60 Hz AC field alone, but only at certain AC field intensities. Thus, whereas the previous study of regeneration rate effects appeared to involve exclusively resonance interactions, the regeneration anomalies reported here appear to result primarily from Faraday induction coupling.« less
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Characteristics of W Doped Nanocrystalline Carbon Films Prepared by Unbalanced Magnetron Sputtering.
Park, Yong Seob; Park, Chul Min; Kim, Nam-Hoon; Kim, Jae-Moon
2016-05-01
Nanocrystalline tungsten doped carbon (WC) films were prepared by unbalanced magnetron sputtering. Tungsten was used as the doping material in carbon thin films with the aim of application as a contact strip in an electric railway. The structural, physical, and electrical properties of the fabricated WC films with various DC bias voltages were investigated. The films had a uniform and smooth surface. Hardness and frication characteristics of the films were improved, and the resistivity and sheet resistance decreased with increasing negative DC bias voltage. These results are associated with the nanocrystalline WC phase and sp(2) clusters in carbon networks increased by ion bombardment enhanced with increasing DC bias voltage. Consequently, the increase of sp(2) clusters containing WC nanocrystalline in the carbon films is attributed to the improvement in the physical and electrical properties.
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A Merged Dataset for Solar Probe Plus FIELDS Magnetometers
NASA Astrophysics Data System (ADS)
Bowen, T. A.; Dudok de Wit, T.; Bale, S. D.; Revillet, C.; MacDowall, R. J.; Sheppard, D.
2016-12-01
The Solar Probe Plus FIELDS experiment will observe turbulent magnetic fluctuations deep in the inner heliosphere. The FIELDS magnetometer suite implements a set of three magnetometers: two vector DC fluxgate magnetometers (MAGs), sensitive from DC- 100Hz, as well as a vector search coil magnetometer (SCM), sensitive from 10Hz-50kHz. Single axis measurements are additionally made up to 1MHz. To study the full range of observations, we propose merging data from the individual magnetometers into a single dataset. A merged dataset will improve the quality of observations in the range of frequencies observed by both magnetometers ( 10-100 Hz). Here we present updates on the individual MAG and SCM calibrations as well as our results on generating a cross-calibrated and merged dataset.
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Navarro-Sanchez, Erika; Altmeyer, Ralf; Amara, Ali; Schwartz, Olivier; Fieschi, Franck; Virelizier, Jean-Louis; Arenzana-Seisdedos, Fernando; Desprès, Philippe
2003-01-01
Dengue virus (DV) is a mosquito-borne flavivirus that causes haemorrhagic fever in humans. DV primarily targets immature dendritic cells (DCs) after a bite by an infected mosquito vector. Here, we analysed the interactions between DV and human-monocyte-derived DCs at the level of virus entry. We show that the DC-specific ICAM3-grabbing non-integrin (DC-SIGN) molecule, a cell-surface, mannose-specific, C-type lectin, binds mosquito-cell-derived DVs and allows viral replication. Conclusive evidence for the involvement of DC-SIGN in DV infection was obtained by the inhibition of viral infection by anti-DC-SIGN antibodies and by the soluble tetrameric ectodomain of DC-SIGN. Our data show that DC-SIGN functions as a DV-binding lectin by interacting with the DV envelope glycoprotein. Mosquito-cell-derived DVs may have differential infectivity for DC-SIGN-expressing cells. We suggest that the differential use of DC-SIGN by viral envelope glycoproteins may account for the immunopathogenesis of DVs. PMID:12783086
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2009-09-10
Howard University 2300 6th Street NW, Room 1016 Washington, D.C. 20059 Air Force Office of Scientific Research 875 North Randolph Street Room 3112...Department of Electrical Engineering, Howard University , Washington, DC 20059 Room temperature quantum efficiencies of Ag/n-Si composite...at the Howard University CREST Center for Nanomaterials Characterization Science and Processing Technology were used in this investigation. The
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Ganther, Jr., Kenneth R.; Snapp, Lowell D.
2002-09-10
A flux locked loop for providing an electrical feedback signal, the flux locked loop employing radio-frequency components and technology to extend the flux modulation frequency and tracking loop bandwidth. The flux locked loop of the present invention has particularly useful application in read-out electronics for DC SQUID magnetic measurement systems, in which case the electrical signal output by the flux locked loop represents an unknown magnetic flux applied to the DC SQUID.
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The decolouration of methyl orange using aluminum foam, ultrasound and direct electric current
NASA Astrophysics Data System (ADS)
Liu, C. M.; Huang, X. Y.; Zhang, H. Y.; Dai, J. D.; Ning, C. C.
2018-01-01
The decolouration of methyl orange (MO) using aluminum (Al) foam, ultrasound and direct electric current (DC) is investigated. The decolouration rate (DR) of MO using only Al foam is low because there is a passivation oxide layer on the Al foam surface. Due to the low utilization of ultrasound in MO water solution medium, the DR of MO using only ultrasonic irradiation is also poor. The DR of MO is greatly increased when Al foam, ultrasonic irradiation and DC are used together. There is good synergistic effect between Al foam, ultrasound and DC in decolouration of MO. This enhancement of DR may be related to the cavitation, cleaning of Al foam surface and water electrolysis. Due to the surface charge on wire carrying stationary current, Al foam with DC acts like a serious anodes and cathodes and makes water electrolysis giving hydrogen gas to cleavage azo bond. The DC applied on Al foam is beneficial for reductive decolouration of MO. Our results show that DC is a new way for the reductive decolouration MO in water.
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NASA Astrophysics Data System (ADS)
Jung, S.; Lee, J. H.; Yoon, M.; Lee, H.; Jang, G.
The study of the application process of the relatively small size 'Superconducting Flywheel Energy Storage (SFES)' system is conducted to regulate voltage fluctuation of the DC On-Line Electric Vehicle (OLEV) system, which is designed by using DC power system network. It is recommended to construct the power conversion system nearby the substation because the charging system is under the low voltage. But as the system is usually built around urban area and it makes hard to construct the subsystems at every station, voltage drop can occur in power supply inverter that is some distance from the substation. As the alternative of this issue, DC distribution system is recently introduced and has possibility to solve the above issue. In this paper, SFES is introduced to solve the voltage drop under the low voltage distribution system by using the concept of the proposed DC OLEV which results in building the longer distance power supply system. The simulation to design the SFES by using DC power flow analysis is carried out and it is verified in this paper.
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Prototype Combined Heater/Thermoelectric Power Generator for Remote Applications
NASA Astrophysics Data System (ADS)
Champier, D.; Favarel, C.; Bédécarrats, J. P.; Kousksou, T.; Rozis, J. F.
2013-07-01
This study presents a prototype thermoelectric generator (TEG) developed for remote applications in villages that are not connected to the electrical power grid. For ecological and economic reasons, there is growing interest in harvesting waste heat from biomass stoves to produce some electricity. Because regular maintenance is not required, TEGs are an attractive choice for small-scale power generation in inaccessible areas. The prototype developed in our laboratory is especially designed to be implemented in stoves that are also used for domestic hot water heating. The aim of this system is to provide a few watts to householders, so they have the ability to charge cellular phones and radios, and to get some light at night. A complete prototype TEG using commercial (bismuth telluride) thermoelectric modules has been built, including system integration with an electric DC/DC converter. The DC/DC converter has a maximum power point tracker (MPPT) driven by an MC9SO8 microcontroller, which optimizes the electrical energy stored in a valve-regulated lead-acid battery. Physical models were used to study the behavior of the thermoelectric system and to optimize the performance of the MPPT. Experiments using a hot gas generator to simulate the exhaust of the combustion chamber of a stove are used to evaluate the system. Additionally, potential uses of such generators are presented.
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Research on Control System of Three - phase Brushless DC Motor for Electric Vehicle
NASA Astrophysics Data System (ADS)
Wang, Zhiwei; Jin, Hai; Guo, Jie; Su, Jie; Wang, Miao
2017-12-01
In order to study the three-phase brushless motor control system of electric vehicle, Freescale9S12XS128 chip is used as the control core, and the power MOSFET is used as the inverter device. The software is compiled by Codewarrior software. The speed control link adopts open-loop control, and the control chip collects the external sensor signal voltage Change control PWM signal output control three-phase brushless DC motor speed. The whole system consists of Hall position detection module, current detection module, power drive module and voltage detection module. The basic functions of three-phase brushless DC motor drive control are realized.
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The Development and Demonstration of a 360m/10 kA HTS DC Power Cable
NASA Astrophysics Data System (ADS)
Xiao, Liye
With the quick development of renewable energy, it is expected that the electric power from renewable energy would be the dominant one for the future power grid. Due to the specialty of the renewable energy, the HVDC power transmission would be very useful for the transmission of electric power from renewable energy. DC power cable made of High Tc Superconductor (HTS) would be a possible alternative for the construction of HVDC power transmission system. In this chapter, we report the development and demonstration of a 360 m/10 kA HTS DC power cable and the test results.
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Conformal Galilei algebras, symmetric polynomials and singular vectors
NASA Astrophysics Data System (ADS)
Křižka, Libor; Somberg, Petr
2018-01-01
We classify and explicitly describe homomorphisms of Verma modules for conformal Galilei algebras cga_ℓ (d,C) with d=1 for any integer value ℓ \\in N. The homomorphisms are uniquely determined by singular vectors as solutions of certain differential operators of flag type and identified with specific polynomials arising as coefficients in the expansion of a parametric family of symmetric polynomials into power sum symmetric polynomials.
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1992-02-01
Division (Code RM) ONERA Office of Aeronautics & Space Technology 29 ave de la Division Leclerc NASA Hq 92320 Chfitillon Washington DC 20546 France United...Vector of thickness variables. V’ = [ t2 ........ tN Vector of thickness changes. AV ’= [rt, 5t2 ......... tNJ TI 7-9 Vector of strain derivatives. F...ds, ds, I d, 1i’,= dt, dr2 ........ dt--N Vector of buckling derivatives. dX d). , dt1 dt2 dtN Then 5F= Vs’i . AV and SX V,’. AV The linearised
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NASA Astrophysics Data System (ADS)
Castellví, Quim; Mercadal, Borja; Moll, Xavier; Fondevila, Dolors; Andaluz, Anna; Ivorra, Antoni
2018-02-01
Electroporation-based treatments typically consist of the application of high-voltage dc pulses. As an undesired side effect, these dc pulses cause electrical stimulation of excitable tissues such as motor nerves. The present in vivo study explores the use of bursts of sinusoidal voltage in a frequency range from 50 kHz to 2 MHz, to induce irreversible electroporation (IRE) whilst avoiding neuromuscular stimulation. A series of 100 dc pulses or sinusoidal bursts, both with an individual duration of 100 µs, were delivered to rabbit liver through thin needles in a monopolar electrode configuration, and thoracic movements were recorded with an accelerometer. Tissue samples were harvested three hours after treatment and later post-processed to determine the dimensions of the IRE lesions. Thermal damage due to Joule heating was ruled out via computer simulations. Sinusoidal bursts with a frequency equal to or above 100 kHz did not cause thoracic movements and induced lesions equivalent to those obtained with conventional dc pulses when the applied voltage amplitude was sufficiently high. IRE efficacy dropped with increasing frequency. For 100 kHz bursts, it was estimated that the electric field threshold for IRE is about 1.4 kV cm-1 whereas that of dc pulses is about 0.5 kV cm-1.
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Vectorial Command of Induction Motor Pumping System Supplied by a Photovoltaic Generator
NASA Astrophysics Data System (ADS)
Makhlouf, Messaoud; Messai, Feyrouz; Benalla, Hocine
2011-01-01
With the continuous decrease of the cost of solar cells, there is an increasing interest and needs in photovoltaic (PV) system applications following standard of living improvements. Water pumping system powered by solar-cell generators are one of the most important applications. The fluctuation of solar energy on one hand, and the necessity to optimise available solar energy on the other, it is useful to develop new efficient and flexible modes to control motors that entrain the pump. A vectorial control of an asynchronous motor fed by a photovoltaic system is proposed. This paper investigates a photovoltaic-electro mechanic chain, composed of a PV generator, DC-AC converter, a vector controlled induction motor and centrifugal pump. The PV generator is forced to operate at its maximum power point by using an appropriate search algorithm integrated in the vector control. The optimization is realized without need to adding a DC-DC converter to the chain. The motor supply is also ensured in all insolation conditions. Simulation results show the effectiveness and feasibility of such an approach.
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NASA Astrophysics Data System (ADS)
Geetha, A.; Subramani, C.; Thamizh Thentral, T. M.; Krithika, V.; Usha, S.
2018-04-01
Non isolated Bidirectional DC-DC Converter (NIBDDC) is a good interface between DC source and inverter Fed induction motor drive. This paper deals with comparison between open loop and PI controlled Bidirectional DC to DC Converter Inverter System (BDDCIS). The modelling and control of BDDC is becomes an important issue. Open loop BDDCIS and closed loop PI controlled BDDCIS are designed, modelled and simulated using Matlab- simulink and their results are presented. The investigations indicate superior performance of PI controlled BDDCIS. The proposed BDDCIS has advantages like bidirectional power transfer ability, reduced hardware count and improved dynamic response.
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Study of temperature dependent electrical properties of Se80-xTe20Bix (x = 0, 3, 6) glasses
NASA Astrophysics Data System (ADS)
Deepika, Singh, Hukum
2018-05-01
This paper reports the variation in electrical properties of Se80-xTe20Bix (x = 0, 3, 6) glasses studied at different temperatures. The amorphous samples were prepared using the melt quenching method and the electrical measurements were performed on Keithley Electrometer in the temperature ranging from 298-373 K. The I-V characteristics were noted at different temperatures and the data obtained was analysed to get dc electrical conductivity and activation energy of electrical conduction. Further, Mott's 3D VRH model has been applied to obtain density of states, hopping range and hopping energy at different temperatures. The obtained results show that dc electrical conductivity increases with increase in Bi composition in Se-Te system. These compositions also show close agreement to Mott's VRH model.
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Multiport power router and its impact on future smart grids
NASA Astrophysics Data System (ADS)
Kado, Yuichi; Shichijo, Daiki; Wada, Keiji; Iwatsuki, Katsumi
2016-07-01
We propose a Y configuration power router as a unit cell to easily construct a power delivery system that can meet many types of user requirements. The Y configuration power router controls the direction and magnitude of power flows between three ports regardless of DC or AC. We constructed a prototype three-way isolated DC/DC converter that is the core unit of the Y configuration power router. The electrical insulation between three ports assures safety and reliability for power network systems. We then tested the operation of power flow control. The experimental results revealed that our methodology based on a governing equation was appropriate to control the power flow of the three-way DC/DC converter. In addition, a distribution network composed of power routers had the ability to easily enable interchanges of electrical power between autonomous microgrid cells. We also explored the requirements for communication between energy routers to achieve dynamic adjustments of energy flows in a coordinated manner and their impact on resilient power grid systems.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui
A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of themore » one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.« less
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Tunable surface plasmon instability leading to emission of radiation
DOE Office of Scientific and Technical Information (OSTI.GOV)
Gumbs, Godfrey; Donostia International Physics Center; Iurov, Andrii, E-mail: aiurov@chtm.unm.edu
2015-08-07
We propose a new approach for energy conversion from a dc electric field to tunable terahertz emission based on hybrid semiconductors by combining two-dimensional (2D) crystalline layers and a thick conducting material with possible applications for chemical analysis, security scanning, medical (single-molecule) imaging, and telecommunications. The hybrid nano-structure may consist of a single or pair of sheets of graphene, silicene, or a 2D electron gas. When an electric current is passed through a 2D layer, we discover that two low-energy plasmon branches exhibit a characteristic loop in their dispersion before they merge into an unstable region beyond a critical wavemore » vector q{sub c}. This finite q{sub c} gives rise to a wavenumber cutoff in the emission dispersion of the surface plasmon induced instability and emission of radiation (spiler). However, there is no instability for a single driven layer far from the conductor, and the instability of an isolated pair of 2D layers occurs without a wavenumber cutoff. The wavenumber cutoff is found to depend on the conductor electron density, layer separation, distances of layers from the conductor surface, and the driving-current strength.« less
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Development of Short Gate FET’s.
1983-12-01
Electrical Engineering AREA OK UIT NUMBERS S School of Engineering, Howard University 61102F 2300 Sixth St. N.W. Washington D.C. 20059 2305/Cl CITROLLING... Howard University Washington# D.C. 20059 64 04 24 021 RESEARCH OBJECTIVES The principal objective of this research is to try to under- stand the... Howard University Washington, D.C. 20059 (202)636-6684 James Comas Naval Research Laboratory, Code 6823 Washington, D.C. 20375 (202)767-3097
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Direct current stimulation of titanium interbody fusion devices in primates.
Cook, Stephen D; Patron, Laura P; Christakis, Petros M; Bailey, Kirk J; Banta, Charles; Glazer, Paul A
2004-01-01
The fusion rate for anterior lumbar interbody fusion (ALIF) varies widely with the use of different interbody devices and bone graft options. Adjunctive techniques such as electrical stimulation may improve the rate of bony fusion. To determine if direct current (DC) electrical stimulation of a metallic interbody fusion device enhanced the incidence or extent of anterior bony fusion. ALIF was performed using titanium alloy interbody fusion devices with and without adjunctive DC electrical stimulation in nonhuman primates. ALIF was performed through an anterolateral approach in 35 macaques with autogenous bone graft and either a titanium alloy (Ti-6Al-4V) fusion device or femoral allograft ring. The fusion devices of 19 animals received high (current density 19.6 microA/cm2) or low (current density 5.4 microA/cm2) DC electrical stimulation using an implanted generator for a 12- or 26-week evaluation period. Fusion sites were studied using serial radiographs, computed tomography imaging, nondestructive mechanical testing and qualitative and semiquantitative histology. Fusion was achieved with the titanium fusion device and autogenous bone graft. At 12 weeks, the graft was consolidating and early to moderate bridging callus was observed in and around the device. By 26 weeks, the anterior callus formation was more advanced with increased evidence of bridging trabeculations and early bone remodeling. The callus formation was not as advanced or abundant for the allograft ring group. Histology revealed the spinal fusion device had an 86% incidence of bony fusion at 26 weeks compared with a 50% fusion rate for the allograft rings. DC electrical stimulation of the fusion device had a positive effect on anterior interbody fusion by increasing both the presence and extent of bony fusion in a current density-dependent manner. Adjunctive DC electrical stimulation of the fusion device improved the rate and extent of bony fusion compared with a nonstimulated device. The fusion device was equivalent to or better than the femoral allograft ring in all evaluations. The use of adjunctive direct current electrical stimulation may provide a means of improving anterior interbody fusion.
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Backus, Elaine A; Cervantes, Felix A; Godfrey, Larry; Akbar, Waseem; Clark, Thomas L; Rojas, Maria G
This study is the first to fully evaluate whether electrical signals applied to large insects during electropenetrography (EPG; also called electrical penetration graph) negatively affect insect behavior. During EPG, electrical signals are applied to plants, and thus to the gold-wire-tethered insects feeding on them. The insect completes an electrical circuit whose changes in voltage reflect the insect's stylet probing/penetration behaviors, recorded as waveform output. For nearly 50 years of EPG science, evidence has supported that there are no or negligible effects on tiny insects from applied electricity during EPG. Recently however, EPG studies of large-bodied hemipterans such as heteropterans and sharpshooter leafhoppers have been published. The wider stylet diameters of such large insects cause them to have lower inherent resistances to applied signals compared with smaller insects, conveying more electrical current. The present study asked whether such increased currents would affect insect stylet probing, by comparing Lygus lineolaris behaviors on pin-head cotton squares using an AC-DC electropenetrograph. Effects of AC or DC applied signals were separately examined in two factorial studies, each comparing four input resistor (Ri) levels (10 6 , 10 7 , 10 8 and 10 9 Ω) and four applied voltage levels (2, 60, 150 and 250 mV). Results showed that changes in both probing and non-probing behaviors were indeed caused by changing signal type, Ri level, or applied voltage. Negative effects on feeding were numerically greater overall for DC than AC applied signals, perhaps due to muscular tetany from DC; however, AC versus DC could not be statistically tested. Results strongly support the need for flexible Ri and applied voltage levels and types, to tailor instrument settings to the size and special needs of each insect subject. Our findings will facilitate further EPG studies of Lygus spp., such as host plant resistance or insecticidal assays/bioassays to assess mode of action and appropriate dosage. It is hoped that this study will also inform EPG studies of similar, large heteropterans in the future. Published by Elsevier Ltd.
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Experimental insight into the magnetic and electrical properties of amorphous Ge1-xMnx
NASA Astrophysics Data System (ADS)
Conta, Gianluca; Amato, Giampiero; Coïsson, Marco; Tiberto, Paola
2017-12-01
We present a study of the electrical and magnetic properties of the amorphous Ge1-xMnx.DMS, with 2% ≤ x ≤ 17%, by means of SQUID magnetometry and low temperature DC measurements. The thin films were grown by physical vapour deposition at 50°C in ultrahigh vacuum. The DC electrical characterizations show that variable range hopping is the main mechanism of charge transport below room temperature. Magnetic characterization reveals that a unique and smooth magnetic transition is present in our samples, which can be attributed to ferromagnetic percolation of bound magnetic polarons.
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Electric and magnetic superlattices in trilayer graphene
NASA Astrophysics Data System (ADS)
Uddin, Salah; Chan, K. S.
2016-01-01
The properties of one dimensional Kronig-Penney type of periodic electric and vector potential on ABC-trilayer graphene superlattices are investigated. The energy spectra obtained with periodic vector potentials shows the emergence of extra Dirac points in the energy spectrum with finite energies. For identical barrier and well widths, the original as well as the extra Dirac points are located in the ky = 0 plane. An asymmetry between the barrier and well widths causes a shift in the extra Dirac points away from the ky = 0 plane. Extra Dirac points having same electron hole crossing energy as that of the original Dirac point as well as finite energy Dirac points are generated in the energy spectrum when periodic electric potential is applied to the system. By applying electric and vector potential together, the symmetry of the energy spectrum about the Fermi level is broken. A tunable band gap is induced in the energy spectrum by applying both electric and vector potential simultaneously with different barrier and well widths.
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DC conductivity of a suspension of insulating particles with internal rotation
NASA Astrophysics Data System (ADS)
Pannacci, N.; Lemaire, E.; Lobry, L.
2009-04-01
We analyse the consequences of Quincke rotation on the conductivity of a suspension. Quincke rotation refers to the spontaneous rotation of insulating particles dispersed in a slightly conducting liquid and subject to a high DC electric field: above a critical field, each particle rotates continuously around itself with an axis pointing in any direction perpendicular to the DC field. When the suspension is subject to an electric field lower than the threshold one, the presence of insulating particles in the host liquid decreases the bulk conductivity since the particles form obstacles to ion migration. But for electric fields higher than the critical one, the particles rotate and facilitate ion migration: the effective conductivity of the suspension is increased. We provide a theoretical analysis of the impact of Quincke rotation on the apparent conductivity of a suspension and we present experimental results obtained with a suspension of PMMA particles dispersed in weakly conducting liquids.
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NASA Technical Reports Server (NTRS)
Edie, P. C.
1981-01-01
Performance data on the Prestolite MTC-4001 series wound dc motor and General Electric EV-1 Chopper Controller is supplied for the electric vehicle manufacturer. Data are provided for both straight and chopped dc input to the motor, at 2 motor temperature levels. Testing was done at 6 voltage increments to the motor, and 2 voltage increments to the controller. Data results are presented in both tabular and graphical forms. Tabular information includes motor voltage and current input data, motor speed and torque output data, power data and temperature data. Graphical information includes torque-speed, motor power output-speed, torque-current, and efficiency-speed plots under the various operating conditions. The data resulting from this testing show the speed-torque plots to have the most variance with operating temperature. The maximum motor efficiency is between 76% and 82%, regardless of temperature or mode of operation.
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Romero, Luz; Binions, Russell
2013-11-05
Titanium dioxide thin films were deposited on fluorine doped tin oxide glass substrate from the electric field assisted aerosol chemical vapor deposition (EACVD) reaction of titanium isopropoxide (TTIP, Ti(OC3H7)4) in toluene on glass substrates at a temperature of 450 °C. DC electric fields were generated by applying a potential difference between the electrodes of the transparent coated oxide coated glass substrates during the deposition. The deposited films were characterized using scanning electron microscopy, X-ray diffraction, atomic force microscopy, Raman spectroscopy, and UV-vis spectroscopy. The photoactivity and hydrophilicity of the deposited films were also analyzed using a dye-ink test and water-contact angle measurements. The characterization work revealed that the incorporation of DC electric fields produced significant reproducible changes in the film microstructure, preferred crystallographic orientation, roughness, and film thickness. Photocatalytic activity was calculated from the half-time (t1/2) or time taken to degrade 50% of the initial resazurin dye concentration. A large improvement in photocatalytic activity was observed for films deposited using an electric field with a strong orientation in the (004) direction (t1/2 17 min) as compared to a film deposited with no electric field (t1/2 40 min).
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Akkas, Oguz; Lee, Cheng Hsien; Hu, Yu Hen; Harris Adamson, Carisa; Rempel, David; Radwin, Robert G
2017-12-01
Two computer vision algorithms were developed to automatically estimate exertion time, duty cycle (DC) and hand activity level (HAL) from videos of workers performing 50 industrial tasks. The average DC difference between manual frame-by-frame analysis and the computer vision DC was -5.8% for the Decision Tree (DT) algorithm, and 1.4% for the Feature Vector Training (FVT) algorithm. The average HAL difference was 0.5 for the DT algorithm and 0.3 for the FVT algorithm. A sensitivity analysis, conducted to examine the influence that deviations in DC have on HAL, found it remained unaffected when DC error was less than 5%. Thus, a DC error less than 10% will impact HAL less than 0.5 HAL, which is negligible. Automatic computer vision HAL estimates were therefore comparable to manual frame-by-frame estimates. Practitioner Summary: Computer vision was used to automatically estimate exertion time, duty cycle and hand activity level from videos of workers performing industrial tasks.
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NASA Astrophysics Data System (ADS)
Jabbari, Ali
2018-01-01
Surface inset permanent magnet DC machine can be used as an alternative in automation systems due to their high efficiency and robustness. Magnet segmentation is a common technique in order to mitigate pulsating torque components in permanent magnet machines. An accurate computation of air-gap magnetic field distribution is necessary in order to calculate machine performance. An exact analytical method for magnetic vector potential calculation in surface inset permanent magnet machines considering magnet segmentation has been proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in polar coordinate by using sub-domain method. One of the main contributions of the paper is to derive an expression for the magnetic vector potential in the segmented PM region by using hyperbolic functions. The developed method is applied on the performance computation of two prototype surface inset magnet segmented motors with open circuit and on load conditions. The results of these models are validated through FEM method.
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NASA Astrophysics Data System (ADS)
Ishisaka, K.; Yamamoto, M.; Yokoyama, T.; Tanaka, M.; Abe, T.; Kumamoto, A.
2015-12-01
In the middle latitude ionospheric F region, mainly in summer, wave structures of electron density that have wave length of 100-200 km and period of one hour are observed. This phenomena is called Medium Scale Traveling Ionosphiric Disturbance; MSTID. MSTID has been observed by GPS receiving network, and its characteristic were studied. In the past, MSTID was thought to be generated by the Perkins instability, but its growth ratio was too small to be effective so far smaller than the real. Recently coupling process between ionospheric E and F regions are studied by using two radars and by computer simulations. Through these studies, we now have hypothesis that MSTID is generated by the combination of E-F region coupling and Perkins instability. The S-520-27 sounding rocket experiment on E-layer and F-layer was planned in order to verify this hypothesis. S-520-27 sounding rocket was launched at 23:57 JST on 20th July, 2013 from JAXA Uchinoura Space Center. S-520-27 sounding rocket reached 316km height. The S-520-27 payload was equipped with Electric Field Detector (EFD) with a two set of orthogonal double probes to measure DC electric field in the spin plane of the payload. The electrodes of two double probe antennas were used to gather the potentials which were detected with high impedance pre-amplifier using the floating (unbiased) double probe technique. As a results of measurements of DC electric fields by the EFD, the natural electric field was about +/-5mV/m, and varied the direction from southeast to east. Then the electric field was mapped to the horizontal plane at 280km height along the geomagnetic field line. In this presentation, we show the detail result of DC electric field measurement by S-520-27 sounding rocket and then we discuss about the correlation between the natural electric field and TEC variation by using the GPS-TEC.
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Oddy, M H; Santiago, J G
2004-01-01
We have developed a method for measuring the electrophoretic mobility of submicrometer, fluorescently labeled particles and the electroosmotic mobility of a microchannel. We derive explicit expressions for the unknown electrophoretic and the electroosmotic mobilities as a function of particle displacements resulting from alternating current (AC) and direct current (DC) applied electric fields. Images of particle displacements are captured using an epifluorescent microscope and a CCD camera. A custom image-processing code was developed to determine image streak lengths associated with AC measurements, and a custom particle tracking velocimetry (PTV) code was devised to determine DC particle displacements. Statistical analysis was applied to relate mobility estimates to measured particle displacement distributions.
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Design of a -1 MV dc UHV power supply for ITER NBI
NASA Astrophysics Data System (ADS)
Watanabe, K.; Yamamoto, M.; Takemoto, J.; Yamashita, Y.; Dairaku, M.; Kashiwagi, M.; Taniguchi, M.; Tobari, H.; Umeda, N.; Sakamoto, K.; Inoue, T.
2009-05-01
Procurement of a dc -1 MV power supply system for the ITER neutral beam injector (NBI) is shared by Japan and the EU. The Japan Atomic Energy Agency as the Japan Domestic Agency (JADA) for ITER contributes to the procurement of dc -1 MV ultra-high voltage (UHV) components such as a dc -1 MV generator, a transmission line and a -1 MV insulating transformer for the ITER NBI power supply. The inverter frequency of 150 Hz in the -1 MV power supply and major circuit parameters have been proposed and adopted in the ITER NBI. The dc UHV insulation has been carefully designed since dc long pulse insulation is quite different from conventional ac insulation or dc short pulse systems. A multi-layer insulation structure of the transformer for a long pulse up to 3600 s has been designed with electric field simulation. Based on the simulation the overall dimensions of the dc UHV components have been finalized. A surge energy suppression system is also essential to protect the accelerator from electric breakdowns. The JADA contributes to provide an effective surge suppression system composed of core snubbers and resistors. Input energy into the accelerator from the power supply can be reduced to about 20 J, which satisfies the design criteria of 50 J in total in the case of breakdown at -1 MV.
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Code of Federal Regulations, 2012 CFR
2012-01-01
... ELECTRIC ENGINEERING, ARCHITECTURAL SERVICES AND DESIGN POLICIES AND PROCEDURES Electric System Design § 1724.55 Dam safety. (a) The provisions of this section apply only to RUS financed electric system... at RUS, Electric Staff Division, 1400 Independence Avenue, SW., Washington, DC, Room 1246-S, and at...
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Code of Federal Regulations, 2013 CFR
2013-01-01
... ELECTRIC ENGINEERING, ARCHITECTURAL SERVICES AND DESIGN POLICIES AND PROCEDURES Electric System Design § 1724.55 Dam safety. (a) The provisions of this section apply only to RUS financed electric system... at RUS, Electric Staff Division, 1400 Independence Avenue, SW., Washington, DC, Room 1246-S, and at...
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Code of Federal Regulations, 2010 CFR
2010-01-01
... ELECTRIC ENGINEERING, ARCHITECTURAL SERVICES AND DESIGN POLICIES AND PROCEDURES Electric System Design § 1724.55 Dam safety. (a) The provisions of this section apply only to RUS financed electric system... at RUS, Electric Staff Division, 1400 Independence Avenue, SW., Washington, DC, Room 1246-S, and at...
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Code of Federal Regulations, 2011 CFR
2011-01-01
... ELECTRIC ENGINEERING, ARCHITECTURAL SERVICES AND DESIGN POLICIES AND PROCEDURES Electric System Design § 1724.55 Dam safety. (a) The provisions of this section apply only to RUS financed electric system... at RUS, Electric Staff Division, 1400 Independence Avenue, SW., Washington, DC, Room 1246-S, and at...
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Code of Federal Regulations, 2014 CFR
2014-01-01
... ELECTRIC ENGINEERING, ARCHITECTURAL SERVICES AND DESIGN POLICIES AND PROCEDURES Electric System Design § 1724.55 Dam safety. (a) The provisions of this section apply only to RUS financed electric system... at RUS, Electric Staff Division, 1400 Independence Avenue, SW., Washington, DC, Room 1246-S, and at...
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Rural Electric Youth Tour Packet.
ERIC Educational Resources Information Center
National Rural Electric Cooperative Association, Washington, DC.
This packet of materials provides information about tours for rural secondary students in Washington, D.C., sponsored jointly by the National Rural Electric Cooperative Association (NRECA), state rural electric cooperatives, and statewide associations of rural electric systems. Since 1958 this program has selected high school students to visit…
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Fault tolerant vector control of induction motor drive
NASA Astrophysics Data System (ADS)
Odnokopylov, G.; Bragin, A.
2014-10-01
For electric composed of technical objects hazardous industries, such as nuclear, military, chemical, etc. an urgent task is to increase their resiliency and survivability. The construction principle of vector control system fault-tolerant asynchronous electric. Displaying recovery efficiency three-phase induction motor drive in emergency mode using two-phase vector control system. The process of formation of a simulation model of the asynchronous electric unbalance in emergency mode. When modeling used coordinate transformation, providing emergency operation electric unbalance work. The results of modeling transient phase loss motor stator. During a power failure phase induction motor cannot save circular rotating field in the air gap of the motor and ensure the restoration of its efficiency at rated torque and speed.
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Novel non-equilibrium modelling of a DC electric arc in argon
NASA Astrophysics Data System (ADS)
Baeva, M.; Benilov, M. S.; Almeida, N. A.; Uhrlandt, D.
2016-06-01
A novel non-equilibrium model has been developed to describe the interplay of heat and mass transfer and electric and magnetic fields in a DC electric arc. A complete diffusion treatment of particle fluxes, a generalized form of Ohm’s law, and numerical matching of the arc plasma with the space-charge sheaths adjacent to the electrodes are applied to analyze in detail the plasma parameters and the phenomena occurring in the plasma column and the near-electrode regions of a DC arc generated in atmospheric pressure argon for current levels from 20 A up to 200 A. Results comprising electric field and potential, current density, heating of the electrodes, and effects of thermal and chemical non-equilibrium are presented and discussed. The current-voltage characteristic obtained is in fair agreement with known experimental data. It indicates a minimum for arc current of about 80 A. For all current levels, a field reversal in front of the anode accompanied by a voltage drop of (0.7-2.6) V is observed. Another field reversal is observed near the cathode for arc currents below 80 A.
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Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments
NASA Astrophysics Data System (ADS)
Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf, Marc
2017-01-01
Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning.
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Wang, Tengxing; Jiang, Wei; Divan, Ralu; ...
2017-08-03
A Permalloy (Py) thin film enabled tunable 3-D solenoid inductor is designed and fabricated. The special configuration of magnetic core is discussed and by selectively patterning Py thin film, the proposed tunable inductor can work at frequency up to several GHz range. The inductance of the solenoid inductor can be electrically tuned by dc current and the tunability is above 10%. Utilizing the implemented Py enabled tunable solenoid inductor and Lead Zirconate Titanate (PZT) thin film enabled metal-insulator-metal (MIM) capacitor, a compact fully electrically tunable lumped elements phase shifter is achieved. The tunable phase shifter has both inductive and capacitivemore » tunability and the dual tunability significantly improves the tuning range and design flexibility. Moreover, the dual tunability is able to retain the equivalent characteristic impedance of the device in the process of the phase being tuned. Here, the phase of the device can be tuned by fully electrical methods and when dc current and dc voltage are provided, the length normalized phase tunability is up to 210°/cm« less
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Sant, Himanshu J; Chakravarty, Siddharth; Merugu, Srinivas; Ferguson, Colin G; Gale, Bruce K
2012-10-02
Characterization of polymerized liposomes (PolyPIPosomes) was carried out using a combination of normal dc electrical field-flow fractionation and cyclical electrical field-flow fractionation (CyElFFF) as an analytical technique. The constant nature of the carrier fluid and channel configuration for this technique eliminates many variables associated with multidimensional analysis. CyElFFF uses an oscillating field to induce separation and is performed in the same channel as standard dc electrical field-flow fractionation separation. Theory and experimental methods to characterize nanoparticles in terms of their sizes and electrophoretic mobilities are discussed in this paper. Polystyrene nanoparticles are used for system calibration and characterization of the separation performance, whereas polymerized liposomes are used to demonstrate the applicability of the system to biomedical samples. This paper is also the first to report separation and a higher effective field when CyElFFF is operated at very low applied voltages. The technique is shown to have the ability to quantify both particle size and electrophoretic mobility distributions for colloidal polystyrene nanoparticles and PolyPIPosomes.
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Laser-guided energetic discharges over large air gaps by electric-field enhanced plasma filaments
Théberge, Francis; Daigle, Jean-François; Kieffer, Jean-Claude; Vidal, François; Châteauneuf , Marc
2017-01-01
Recent works on plasma channels produced during the propagation of ultrashort and intense laser pulses in air demonstrated the guiding of electric discharges along the laser path. However, the short plasma lifetime limits the length of the laser-guided discharge. In this paper, the conductivity and lifetime of long plasma channels produced by ultrashort laser pulses is enhanced efficiently over many orders of magnitude by the electric field of a hybrid AC-DC high-voltage source. The AC electric pulse from a Tesla coil allowed to stimulate and maintain the highly conductive channel during few milliseconds in order to guide a subsequent 500 times more energetic discharge from a 30-kV DC source. This DC discharge was laser-guided over an air gap length of two metres, which is more than two orders of magnitude longer than the expected natural discharge length. Long plasma channel induced by laser pulses and stimulated by an external high-voltage source opens the way for wireless and efficient transportation of energetic current pulses over long air gaps and potentially for guiding lightning. PMID:28053312
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PV source based high voltage gain current fed converter
NASA Astrophysics Data System (ADS)
Saha, Soumya; Poddar, Sahityika; Chimonyo, Kudzai B.; Arunkumar, G.; Elangovan, D.
2017-11-01
This work involves designing and simulation of a PV source based high voltage gain, current fed converter. It deals with an isolated DC-DC converter which utilizes boost converter topology. The proposed converter is capable of high voltage gain and above all have very high efficiency levels as proved by the simulation results. The project intends to produce an output of 800 V dc from a 48 V dc input. The simulation results obtained from PSIM application interface were used to analyze the performance of the proposed converter. Transformer used in the circuit steps up the voltage as well as to provide electrical isolation between the low voltage and high voltage side. Since the converter involves high switching frequency of 100 kHz, ultrafast recovery diodes are employed in the circuitry. The major application of the project is for future modeling of solar powered electric hybrid cars.
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Electrical transport in lead-free (Na0.5Bi0.5)1-xSrxTiO3 ceramics (x = 0, 0.01 and 0.02)
NASA Astrophysics Data System (ADS)
Dutkiewicz, E. M.; Suchanicz, J.; Konieczny, K.; Czaja, P.; Kluczewska, K.; Czternastek, H.; Antonova, M.; Sternberg, A.
2017-09-01
Lead-free (Na0.5Bi0.5)1xSrxTiO3 (x = 0, 0.01 and 0.02) ceramics were manufactured through a solid-state mixed oxide method and their ac (σac) and dc (σdc) electric conductivity were studied. It is shown that the low-frequency (100 Hz-1 MHz) ac conductivity obeys a power law σac ∼ ωs characteristic for disordered materials. Both the dc and ac conductivities have thermally activated character and possess linear parts with different activation energies. The calculated activation energies are attributed to different mechanism of conductivity. Frequency dependence of σdc and exponent s is reasonably interpreted by a correlated barrier hopping model. The NBT-ST system is expected to be a new promising candidate for lead-free electronic materials.
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Godbout, Charles; Frenette, Jérôme
2006-01-01
A prevailing paradigm is that electrical fields can promote cell migration and tissue healing. To further validate this paradigm, we tested the hypothesis that periodic direct current (DC) can enhance wound closure using an in vitro dynamic model of cell migration. Layers of primary fibroblasts were wounded and treated with DC under various voltages. Repair area, cell velocity, and directionality as well as lamellipodium area were evaluated at different times. Direct current had no beneficial effect on cell migration. Moreover, prolonged stimulation under the highest voltage led to significant reduction in wound closure and cell velocity. The reduction of membrane protusions in stimulated cells may be associated with the deleterious effect of DC. Contrary to the authors' expectations, they found that periodic DC did not promote wound closure, a finding that emphasizes the need to clarify the complex effects of electrical fields on migrating cells.
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NASA Astrophysics Data System (ADS)
Mahmoud, S. A.; Madi, N. K.; Kassem, M. E.; El-Khatib, A.
A study has been made of the temperature dependence of the d.c. conductivity of pure and borated low density polyethylene LDPE (4% and 8% borax). The above calculations were carried out before and after X-ray irradiation. The irradiation dose was varied from 0 to 1000 rad. The d.c. electrical conductivity of Polyvinyl chloride (PVC) and perspex was measured as a function of temperature ranging from 20°C to 100°C. These samples were irradiated with X-rays of dose 200 rad. The variation of the d.c. conductivity of the treated samples versus temperature was investigated. The results reveal that the d.c. conductivity of LDPE is highly affected by radiation and/or dopant. In addition, the sensitivity of the explored polymers to X-ray irradiation is strongly dependent on its chemical nature.
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Electric power processing, distribution and control for advanced aerospace vehicles.
NASA Technical Reports Server (NTRS)
Krausz, A.; Felch, J. L.
1972-01-01
The results of a current study program to develop a rational basis for selection of power processing, distribution, and control configurations for future aerospace vehicles including the Space Station, Space Shuttle, and high-performance aircraft are presented. Within the constraints imposed by the characteristics of power generation subsystems and the load utilization equipment requirements, the power processing, distribution and control subsystem can be optimized by selection of the proper distribution voltage, frequency, and overload/fault protection method. It is shown that, for large space vehicles which rely on static energy conversion to provide electric power, high-voltage dc distribution (above 100 V dc) is preferable to conventional 28 V dc and 115 V ac distribution per MIL-STD-704A. High-voltage dc also has advantages over conventional constant frequency ac systems in many aircraft applications due to the elimination of speed control, wave shaping, and synchronization equipment.
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2014-05-01
vulnerable to failure is air. This could be a discharge through an air medium or along an air/surface interface. Achieving robustness in dc power...sputtering” arcs) are discharges that are most commonly located in series with the intended load; the electrical impedance of the load limits the...particularly those used at voltages > 1000 V, is detection and measurement of partial- discharge (PD) activity. The presence of PD in a component typically
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Method of measuring the dc electric field and other tokamak parameters
Fisch, Nathaniel J.; Kirtz, Arnold H.
1992-01-01
A method including externally imposing an impulsive momentum-space flux to perturb hot tokamak electrons thereby producing a transient synchrotron radiation signal, in frequency-time space, and the inference, using very fast algorithms, of plasma parameters including the effective ion charge state Z.sub.eff, the direction of the magnetic field, and the position and width in velocity space of the impulsive momentum-space flux, and, in particular, the dc toroidal electric field.
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DC Electric Fields at the Magnetopause
NASA Astrophysics Data System (ADS)
Laakso, H. E.; Escoubet, C. P.; Masson, A.
2014-12-01
In order to understand the transfer of energy, momentum and mass through the magnetopause one needs to know several plasma and field parameters including the DC electric field which is known to be challenging to measure in tenuous plasma regions, e.g. in the inner side of the magnetopause where the density drops below 1/cc. However, each of the Cluster spacecraft carries five different experiments that can provide information about DC electric fields, i.e. double probe antenna (EFW) and electron drift meter (EDI) as well as electron and ion spectrometers (PEACE, CIS-HIA, CIS-CODIF). Each technique is very different and has its own strengths and limitations. Therefore it is important to compare all available measurements before making a judgement on DC electric field variation at the magnetopause; note that only very rarely all five measurements are available at the same time. Although the full-resolution observations in the Cluster archive are calibrated, they can still contain various errors. However, when two experiments show the same field, it is quite likely that this is the right field because the different measurements are based on so complimentary techniques and the field varies so much when the spacecraft moves from the magnetosheath through the magnetopause into the magnetosphere, or vice versa. In this presentation we present several cases of the magnetopause crossings and how the different measurements agree and disagree around the magnetopause region.
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NASA Astrophysics Data System (ADS)
Gao, Lingxiang; Zhao, Xiaopeng
The aqueous ER elastomers, containing crude organic starch particles which dispersed in gelatin/glycerin/water matrix, were prepared with or without the applied DC electric field. The responses of the composite systems to the electric field were tested by the compression modulus and resistance of the elastomers. The result shows that they are enhanced and controlled evidently under an applied DC electric field. The strongest responses appear at 25% weight fraction of starch. In addition, the increment modulus of the elastomer increases with the strength of the applied field within 0.5~1.5 kV/mm, while after the field is stronger than 1.5 kV/mm it doesn't increase with field, appearing "saturation".
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Composite Ceramic Superconducting Wires for Electric Motor Applications
1988-12-30
current a-yi t6-ransition. - Emerson Motor Division has begun work on DC heteropolar and homopolar motor designs. The mechanical stresses on conventional...Emerson Motor Division has begun work on DC heteropolar motor designs and, through Professor Novotny at U. Wisconsin, DC homopolar machines. The...123 3.2 Literature Research .............................. .. 124 3 3.3 Application Study .............................. .. 124 3.3.1 Homopolar Motor
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NASA Astrophysics Data System (ADS)
Wang, Bin; Xu, Jun; Cao, Binggang; Zhou, Xuan
2015-05-01
This paper proposes a novel topology of multimode hybrid energy storage system (HESS) and its energy management strategy for electric vehicles (EVs). Compared to the conventional HESS, the proposed multimode HESS has more operating modes and thus it could in further enhance the efficiency of the system. The rule-based control strategy and the power-balancing strategy are developed for the energy management strategy to realize mode selection and power distribution. Generally, the DC-DC converter will operate at peak efficiency to convey the energy from the batteries to the UCs. Otherwise, the pure battery mode or the pure ultracapacitors (UCs) mode will be utilized without the DC-DC converter. To extend the battery life, the UCs have the highest priority to recycle the energy and the batteries are isolated from being recharged directly during regenerative braking. Simulations and experiments are established to validate the proposed multimode HESS and its energy management strategy. The results reveal that the energy losses in the DC-DC converter, the total energy consumption and the overall system efficiency of the proposed multimode HESS are improved compared to the conventional HESS.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Zhao, Zilai; Gough, Charles
The goal of this Cooperative Agreement was the development of a Next Generation Inverter for General Motors’ electrified vehicles, including battery electric vehicles, range extended electric vehicles, plug-in hybrid electric vehicles and hybrid electric vehicles. The inverter is a critical electronics component that converts battery power (DC) to and from the electric power for the motor (AC).
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Electrically tunable transport and high-frequency dynamics in antiferromagnetic S r3I r2O7
NASA Astrophysics Data System (ADS)
Seinige, Heidi; Williamson, Morgan; Shen, Shida; Wang, Cheng; Cao, Gang; Zhou, Jianshi; Goodenough, John B.; Tsoi, Maxim
2016-12-01
We report dc and high-frequency transport properties of antiferromagnetic S r3I r2O7 . Temperature-dependent resistivity measurements show that the activation energy of this material can be tuned by an applied dc electrical bias. The latter allows for continuous variations in the sample resistivity of as much as 50% followed by a reversible resistive switching at higher biases. Such a switching is of high interest for antiferromagnetic applications in high-speed memory devices. Interestingly, we found the switching behavior to be strongly affected by a high-frequency (microwave) current applied to the sample. The microwaves at 3-7 GHz suppress the dc switching and produce resonancelike features that we tentatively associated with the dissipationless magnonics recently predicted to occur in antiferromagnetic insulators subject to ac electric fields. We have characterized the effects of microwave irradiation on electronic transport in S r3I r2O7 as a function of microwave frequency and power, strength and direction of external magnetic field, strength and polarity of applied dc bias, and temperature. Our observations support the potential of antiferromagnetic materials for high-speed/high-frequency spintronic applications.
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NASA Astrophysics Data System (ADS)
Harish, B. M.; Avinash, B. S.; Chaturmukha, V. S.; Jayanna, H. S.; Suresh, S.; Naveen, C. S.; Lamani, Ashok R.
2018-04-01
NPs of Ce1-xCrxO2 (x=0, 0.04, 0.08, 0.12) have been synthesized by solution combustion method using glycine as fuel. The effect of chromium on structural and dc electrical conductivity of cerium oxide nanoparticles were investigated. The obtained powder is characterized by UV-visible spectrometer, X-ray diffractometer (XRD), Scanning electron microscope (SEM) and Energy dispersive X-Ray analysis (EDS). X-ray diffraction analysis carried out on calcined samples reveals that successful incorporation of Cr2+ in CeO2 lattice where as SEM studies confirms the porous morphological structure of the prepared sample. The Keithley source meter is used to measure the dc conductivity of samples in the temperature range from 303K to 623K. The conductivity was found to be increases with increase of temperature as well as the Cr concentration due to semiconducting behavior of material and change in the charge carrier concentration. The activation energy decreases with increasing chromium concentration. The present work deals with the effect of chromium additive on structural and the D.C electrical properties Ce1-xCrxO2 NPs.
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A novel dual motor drive system for three wheel electric vehicles
NASA Astrophysics Data System (ADS)
Panmuang, Piyapat; Thongsan, Taweesak; Suwapaet, Nuchida; Laohavanich, Juckamass; Photong, Chonlatee
2018-03-01
This paper presents a novel dual motor drive system used for three wheel electric vehicles that have one free wheel at the front and two wheels with a drive system at the end of the vehicles. A novel dual motor drive system consists of two identical DC motors that are independently controlled by its speed-torque controller. Under light load conditions, only one of the DC motors will operate around it rated whilst under hard load conditions both of the DC motors will operate. With this drive system, the motors will operate only at its high performance at rated or else no operate to retain longer lifetime. The simulated results for the Skylab three wheel electric vehicle prototype with 8kW at full load (high torque, low speed) and around 4kW at light/normal operating loads (regular speed-torque) showed that the proposed system provides better dynamic responses with faster overshoot current/voltage recovery time, has lower investment costs, has longer lifetime of the motors and allows the motors to always operate at their high performance and thus achieve more cost effective system compared to a single motor drive system with 8kW DC motors.
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Multiple electrical phase transitions in Al substituted barium hexaferrite
NASA Astrophysics Data System (ADS)
Kumar, Sunil; Supriya, Sweety; Kar, Manoranjan
2017-12-01
Barium hexaferrite is known to be a very good ferromagnetic material. However, it shows very good dielectric properties, i.e., the dielectric constant is comparable to that of the ferroelectric material. However, its crystal symmetry does not allow it to be a ferroelectric material. Hence, the electrical properties have revived the considerable research interest on these materials, not only for academic interest, but also for technological applications. There are a few reports on temperature dependent dielectric behavior of these materials. However, the exact cause of dielectric as well as electrical conductivity is yet to be established. Hence, Al (very good conducting material) substituted barium hexaferrite (BaFe12-xAlxO19, x = 0.0-4.0) has been prepared by following the modified sol-gel method to understand the ac and DC electrical properties of these materials. The crystal structure and parameters have been studied by employing the XRD and FTIR techniques. There are two transition temperatures, which have been observed in the temperature dependent ac dielectric and DC resistivity measurement. The response of dielectric behaviors to temperature is similar to that of the ferroelectric material; however, the dielectric polarization is due to the polaron hopping, which is evident from the DC resistivity analysis. Hence, the present observations lead to understand the electrical properties of barium hexaferrite. The frequency dependent dielectric dispersion can be understood by the modified Debye model. More interestingly, the dielectric constant decreases and DC resistivity increases with the increase in the Al concentration, which has the correlation between bond length modifications in the crystal due to substitution.
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Lightning vulnerability of fiber-optic cables.
DOE Office of Scientific and Technical Information (OSTI.GOV)
Martinez, Leonard E.; Caldwell, Michele
2008-06-01
One reason to use optical fibers to transmit data is for isolation from unintended electrical energy. Using fiber optics in an application where the fiber cable/system penetrates the aperture of a grounded enclosure serves two purposes: first, it allows for control signals to be transmitted where they are required, and second, the insulating properties of the fiber system help to electrically isolate the fiber terminations on the inside of the grounded enclosure. A fundamental question is whether fiber optic cables can allow electrical energy to pass through a grounded enclosure, with a lightning strike representing an extreme but very importantmore » case. A DC test bed capable of producing voltages up to 200 kV was used to characterize electrical properties of a variety of fiber optic cable samples. Leakage current in the samples were measured with a micro-Ammeter. In addition to the leakage current measurements, samples were also tested to DC voltage breakdown. After the fiber optic cables samples were tested with DC methods, they were tested under representative lightning conditions at the Sandia Lightning Simulator (SLS). Simulated lightning currents of 30 kA and 200 kA were selected for this test series. This paper documents measurement methods and test results for DC high voltage and simulated lightning tests performed at the Sandia Lightning Simulator on fiber optic cables. The tests performed at the SLS evaluated whether electrical energy can be conducted inside or along the surface of a fiber optic cable into a grounded enclosure under representative lightning conditions.« less
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Space solar power - An energy alternative
NASA Technical Reports Server (NTRS)
Johnson, R. W.
1978-01-01
The space solar power concept is concerned with the use of a Space Power Satellite (SPS) which orbits the earth at geostationary altitude. Two large symmetrical solar collectors convert solar energy directly to electricity using photovoltaic cells woven into blankets. The dc electricity is directed to microwave generators incorporated in a transmitting antenna located between the solar collectors. The antenna directs the microwave beam to a receiving antenna on earth where the microwave energy is efficiently converted back to dc electricity. The SPS design promises 30-year and beyond lifetimes. The SPS is relatively pollution free as it promises earth-equivalence of 80-85% efficient ground-based thermal power plant.
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Method and apparatus for controlling a microturbine
Garces, Luis Jose; Cardinal, Mark Edward; Sinha, Gautam; Dame, Mark Edward
2005-08-02
An apparatus for controlling a microturbine, the apparatus including: a rectifier adapted for converting at least one generated voltage from the microturbine to a DC link voltage; an inverter adapted for converting the DC link voltage to at least one inverter output voltage, the at least one inverter output voltage being electrically coupled to an external power bus; a starter drive adapted for converting at least one starter input voltage to at least one starter output voltage, the at least one starter input voltage being electrically coupled to the external power bus, the at least one starter output voltage being electrically coupled to the microturbine.
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NASA Astrophysics Data System (ADS)
Mohamed, Ahmed
Efficient and reliable techniques for power delivery and utilization are needed to account for the increased penetration of renewable energy sources in electric power systems. Such methods are also required for current and future demands of plug-in electric vehicles and high-power electronic loads. Distributed control and optimal power network architectures will lead to viable solutions to the energy management issue with high level of reliability and security. This dissertation is aimed at developing and verifying new techniques for distributed control by deploying DC microgrids, involving distributed renewable generation and energy storage, through the operating AC power system. To achieve the findings of this dissertation, an energy system architecture was developed involving AC and DC networks, both with distributed generations and demands. The various components of the DC microgrid were designed and built including DC-DC converters, voltage source inverters (VSI) and AC-DC rectifiers featuring novel designs developed by the candidate. New control techniques were developed and implemented to maximize the operating range of the power conditioning units used for integrating renewable energy into the DC bus. The control and operation of the DC microgrids in the hybrid AC/DC system involve intelligent energy management. Real-time energy management algorithms were developed and experimentally verified. These algorithms are based on intelligent decision-making elements along with an optimization process. This was aimed at enhancing the overall performance of the power system and mitigating the effect of heavy non-linear loads with variable intensity and duration. The developed algorithms were also used for managing the charging/discharging process of plug-in electric vehicle emulators. The protection of the proposed hybrid AC/DC power system was studied. Fault analysis and protection scheme and coordination, in addition to ideas on how to retrofit currently available protection concepts and devices for AC systems in a DC network, were presented. A study was also conducted on the effect of changing the distribution architecture and distributing the storage assets on the various zones of the network on the system's dynamic security and stability. A practical shipboard power system was studied as an example of a hybrid AC/DC power system involving pulsed loads. Generally, the proposed hybrid AC/DC power system, besides most of the ideas, controls and algorithms presented in this dissertation, were experimentally verified at the Smart Grid Testbed, Energy Systems Research Laboratory. All the developments in this dissertation were experimentally verified at the Smart Grid Testbed.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Fendel, Peter; Ganguly, Biswa N.; Bletzinger, Peter
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 gasmore » 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.« less
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Research on spacecraft electrical power conversion
NASA Technical Reports Server (NTRS)
Wilson, T. G.
1974-01-01
The steady state characteristics and starting behavior of some widely used self-oscillating magnetically coupled square wave inverters were studied and the development of LC-tuned square wave inverters is reported. An analysis on high amplitude voltage spikes which occur in dc-to-square-wave parallel converters shows the importance of various circuit parameters for inverter design and for the suppression of spikes. A computerized simulation of an inductor energy storage dc-to-dc converter with closed loop regulators and of a preregulating current step-up converter are detailed. Work continued on the computer aided design of two-winding energy storage dc-to-dc converters.
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Simultaneous distribution of AC and DC power
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.
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Commercial Buildings Research Group. Steve's areas of expertise are electric power distribution systems, DC techniques for maximizing the energy efficiency of electrical distribution systems in commercial buildings
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76 FR 56745 - Notice of Availability of Government-Owned Inventions; Available for Licensing
Federal Register 2010, 2011, 2012, 2013, 2014
2011-09-14
... No. 12/175262: Coupled Electric Field Sensors for DC Target Electric Field Detection; U.S. Patent Application No. 12/732023: Coupled Bi-Stable Microcircuit System for Ultra-Sensitive Electrical and Magnetic... Electric Field Sensing Utilizing Differential Transistors Pairs. FOR FURTHER INFORMATION CONTACT: Brian Suh...
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9 CFR 307.7 - Safety requirements for electrical stimulating (EST) equipment.
Code of Federal Regulations, 2012 CFR
2012-01-01
... requirements for electrical stimulating (EST) equipment. (a) General. Electrical stimulating (EST) equipment is... of facilitating blood removal. These provisions do not apply to electrical equipment used to stun and... generate pulsed DC or AC voltage for stimulation and is separate from the equipment used to apply the...
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9 CFR 307.7 - Safety requirements for electrical stimulating (EST) equipment.
Code of Federal Regulations, 2014 CFR
2014-01-01
... requirements for electrical stimulating (EST) equipment. (a) General. Electrical stimulating (EST) equipment is... of facilitating blood removal. These provisions do not apply to electrical equipment used to stun and... generate pulsed DC or AC voltage for stimulation and is separate from the equipment used to apply the...
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Effect of electrical energy on the efficacy of biofilm treatment using the bioelectric effect
Kim, Young Wook; Subramanian, Sowmya; Gerasopoulos, Konstantinos; Ben-Yoav, Hadar; Wu, Hsuan-Chen; Quan, David; Carter, Karen; Meyer, Mariana T; Bentley, William E; Ghodssi, Reza
2015-01-01
Background/Objectives: The use of electric fields in combination with small doses of antibiotics for enhanced treatment of biofilms is termed the ‘bioelectric effect’ (BE). Different mechanisms of action for the AC and DC fields have been reported in the literature over the last two decades. In this work, we conduct the first study on the correlation between the electrical energy and the treatment efficacy of the bioelectric effect on Escherichia coli K-12 W3110 biofilms. Methods: A thorough study was performed through the application of alternating (AC), direct (DC) and superimposed (SP) potentials of different amplitudes on mature E. coli biofilms. The electric fields were applied in combination with the antibiotic gentamicin (10 μg/ml) over a course of 24 h, after the biofilms had matured for 24 h. The biofilms were analysed using the crystal violet assay, the colony-forming unit method and fluorescence microscopy. Results: Results show that there is no statistical difference in treatment efficacy between the DC-, AC- and SP-based BE treatment of equivalent energies (analysis of variance (ANOVA) P>0.05) for voltages <1 V. We also demonstrate that the efficacy of the BE treatment as measured by the crystal violet staining method and colony-forming unit assay is proportional to the electrical energy applied (ANOVA P<0.05). We further verify that the treatment efficacy varies linearly with the energy of the BE treatment (r2 =0.984). Our results thus suggest that the energy of the electrical signal is the primary factor in determining the efficacy of the BE treatment, at potentials less than the media electrolysis voltage. Conclusions: Our results demonstrate that the energy of the electrical signal, and not the type of electrical signal (AC or DC or SP), is the key to determine the efficacy of the BE treatment. We anticipate that this observation will pave the way for further understanding of the mechanism of action of the BE treatment method and may open new doors to the use of electric fields in the treatment of bacterial biofilms. PMID:28721233
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NASA Astrophysics Data System (ADS)
Yadav, Shivendra; Sharma, Dheeraj; Chandan, Bandi Venkata; Aslam, Mohd; Soni, Deepak; Sharma, Neeraj
2018-05-01
In this article, the impact of gate-underlap with hetero material (low band gap) has been investigated in terms of DC and Analog/RF parameters by proposed device named as hetero material gate-underlap electrically doped TFET (HM-GUL-ED-TFET). Gate-underlap resolves the problem of ambipolarity, gate leakage current (Ig) and slightly improves the gate to drain capacitance, but DC performance is almost unaffected. Further, the use of low band gap material (Si0.5 Ge) in proposed device causes a drastic improvement in the DC as well as RF figures of merit. We have investigated the Si0.5 Ge as a suitable candidate among different low band gap materials. In addition, the sensitivity of gate-underlap in terms of gate to drain inversion and parasitic capacitances has been studied for HM-GUL-ED-TFET. Further, relatively it is observed that gate-underlap is a better way than drain-underlap in the proposed structure to improve Analog/RF performances without degrading the DC parameters of device. Additionally, hetero-junction alignment analysis has been done for fabrication feasibility.
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NASA Astrophysics Data System (ADS)
Liu, Houquan; Zhang, Xingchu
2017-03-01
In a semiconductor, optically excited electron-hole pairs, driven by a strong terahertz (THz) field, can recombine to create THz sidebands in the optical spectrum. The sideband spectrum exhibits a "plateau" up to a cutoff frequency of 3.17Up, where Up is the ponderomotive energy. In this letter, we predict that the bandwidth of this sideband spectrum plateau can be broadened by applying an additional direct-current (DC) electric field. We find that if applying a DC field of EDC=0.2ETHz (where EDC and ETHz are the amplitudes of the DC field and THz field, respectively), the sideband spectrum presents three plateaus with 5.8Up, 10.05Up and 16Up being the cutoff frequencies of the first, second and third plateaus, respectively. This bandwidth broadening occurs because the DC field can increase the kinetic energy that an electron-hole pair can gain from the THz field. This effect means that the bandwidth of the sideband spectrum can be controlled flexibly by changing the DC field, thereby facilitating the ultrafast electro-optical applications of THz sideband generation.
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NASA Astrophysics Data System (ADS)
Tomita, Masaru
The development of a superconducting cable for railways has commenced, assuming that a DC transmission cable will be used for electric trains. The cable has been fabricated based on the results of current testing of a superconducting wire, and various evaluation tests have been performed to determine the characteristics of the cable. A superconducting transmission cable having zero electrical resistance and suitable for railway use is expected to enhance regeneration efficiency, reduce power losses, achieve load leveling and integration of sub-stations, and reduce rail potential.
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Quadrature mixture LO suppression via DSW DAC noise dither
Dubbert, Dale F [Cedar Crest, NM; Dudley, Peter A [Albuquerque, NM
2007-08-21
A Quadrature Error Corrected Digital Waveform Synthesizer (QECDWS) employs frequency dependent phase error corrections to, in effect, pre-distort the phase characteristic of the chirp to compensate for the frequency dependent phase nonlinearity of the RF and microwave subsystem. In addition, the QECDWS can employ frequency dependent correction vectors to the quadrature amplitude and phase of the synthesized output. The quadrature corrections cancel the radars' quadrature upconverter (mixer) errors to null the unwanted spectral image. A result is the direct generation of an RF waveform, which has a theoretical chirp bandwidth equal to the QECDWS clock frequency (1 to 1.2 GHz) with the high Spurious Free Dynamic Range (SFDR) necessary for high dynamic range radar systems such as SAR. To correct for the problematic upconverter local oscillator (LO) leakage, precision DC offsets can be applied over the chirped pulse using a pseudo-random noise dither. The present dither technique can effectively produce a quadrature DC bias which has the precision required to adequately suppress the LO leakage. A calibration technique can be employed to calculate both the quadrature correction vectors and the LO-nulling DC offsets using the radar built-in test capability.
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An SCR inverter for electric vehicles
NASA Technical Reports Server (NTRS)
Latos, T.; Bosack, D.; Ehrlich, R.; Jahns, T.; Mezera, J.; Thimmesch, D.
1980-01-01
An inverter for an electric vehicle propulsion application has been designed and constructed to excite a polyphase induction motor from a fixed propulsion battery source. The inverter, rated at 35kW peak power, is fully regenerative and permits vehicle operation in both the forward and reverse directions. Thyristors are employed as the power switching devices arranged in a dc bus commutated topology. This paper describes the major role the controller plays in generating the motor excitation voltage and frequency to deliver performance similar to dc systems. Motoring efficiency test data for the controller are presented. It is concluded that an SCR inverter in conjunction with an ac induction motor is a viable alternative to present dc vehicle propulsion systems on the basis of performance and size criteria.
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NASA Astrophysics Data System (ADS)
Koppes, Abigail N.; Seggio, Angela M.; Thompson, Deanna M.
2011-08-01
Axonal extension is influenced by a variety of external guidance cues; therefore, the development and optimization of a multi-faceted approach is probably necessary to address the intricacy of functional regeneration following nerve injury. In this study, primary dissociated neonatal rat dorsal root ganglia neurons and Schwann cells were examined in response to an 8 h dc electrical stimulation (0-100 mV mm-1). Stimulated samples were then fixed immediately, immunostained, imaged and analyzed to determine Schwann cell orientation and characterize neurite outgrowth relative to electric field strength and direction. Results indicate that Schwann cells are viable following electrical stimulation with 10-100 mV mm-1, and retain a normal morphology relative to unstimulated cells; however, no directional bias is observed. Neurite outgrowth was significantly enhanced by twofold following exposure to either a 50 mV mm-1 electric field (EF) or co-culture with unstimulated Schwann cells by comparison to neurons cultured alone. Neurite outgrowth was further increased in the presence of simultaneously applied cues (Schwann cells + 50 mV mm-1 dc EF), exhibiting a 3.2-fold increase over unstimulated control neurons, and a 1.2-fold increase over either neurons cultured with unstimulated Schwann cells or the electrical stimulus alone. These results indicate that dc electric stimulation in combination with Schwann cells may provide synergistic guidance cues for improved axonal growth relevant to nerve injuries in the peripheral nervous system.
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Electrodynamics of the stratosphere using 5000 m3 superpressure balloons
NASA Astrophysics Data System (ADS)
Holzworth, R. H.
Recently the U. S. National Science Foundation and NASA have begun support of a long duration balloon-borne experiment to study electrical properties of the upper atmosphere. This research project titled EMA (Electrodynamics of the Middle Atmopshere) involves the design of a microprocessor controlled payload and the launch of up to eight small superpressure balloons during 1982 through early 1984. The primary payload instrument will measure the vector electric field from DC to 10 kHz and the payloads will include instruments to measure local ionization, electrical conductivity, magnetic field, pressure and temperature fluctuations and to record optical lightning. Measurement of these parameters in the stratosphere from a few balloons simultaneously for periods extending over a few solar rotations will enable us to study (1) electrical coupling between the atmosphere and magnetosphere, (2) global current systems, (3) global response to solar flares and magnetospheric storms and many other outstanding problems. In order to obtain long duration flights, it is necessary to fly in the southern hemisphere where the balloons are expected to circle the globe dozens of times in their lifetimes. Thus the balloons will be out of direct communication with any one ground station most of the time so the telemetry will be relayed via satellite. This severely limits the data rates resulting in the need for on-board data processing. This is accomplished through the use of dual microcomputers for data analysis and for telemetry formatting. This talk will concentrate on a description of our payload design as driven by the scientific requirements. Examples of the types of electric field signatures we expect to be able to distinguish will also be presented.
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Lynch, Kyle J; Skalli, Omar; Sabri, Firouzeh
2018-04-20
Externally applied electrical stimulation (ES) has been shown to enhance the nerve regeneration process and to influence the directionality of neurite outgrowth. In addition, the physical and chemical properties of the substrate used for nerve-cell regeneration is critical in fostering regeneration. Previously, we have shown that polyurea-crosslinked silica aerogels (PCSA) exert a positive influence on the extension of neurites by PC-12 cells, a cell-line model widely used to study neurite extension and electrical excitability. In this work, we have examined how an externally applied electric field (EF) influences the extension of neurites in PC-12 cells grown on two substrates: collagen-coated dishes versus collagen-coated crosslinked silica aerogels. The externally applied direct current (DC) bias was applied in vitro using a custom-designed chamber containing polydimethysiloxane (PDMS) embedded copper electrodes to create an electric field across the substrate for the cultured PC-12 cells. Results suggest orientation preference towards the anode, and, on average, longer neurites in the presence of the applied DC bias than with 0 V DC bias. In addition, neurite length was increased in cells grown on silica-crosslinked aerogel when compared to cells grown on regular petri-dishes. These results further support the notion that PCSA is a promising material for nerve regeneration.
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DC current distribution mapping system of the solar panels using a HTS-SQUID gradiometer
NASA Astrophysics Data System (ADS)
Miyazaki, Shingo; Kasuya, Syohei; Mawardi Saari, Mohd; Sakai, Kenji; Kiwa, Toshihiko; Tsukamoto, Akira; Adachi, Seiji; Tanabe, Keiichi; Tsukada, Keiji
2014-05-01
Solar panels are expected to play a major role as a source of sustainable energy. In order to evaluate solar panels, non-destructive tests, such as defect inspections and response property evaluations, are necessary. We developed a DC current distribution mapping system of the solar panels using a High Critical Temperature Superconductor Superconducting Quantum Interference Device (HTS-SQUID) gradiometer with ramp edge type Josephson junctions. Two independent components of the magnetic fields perpendicular to the panel surface (∂Bz/∂x, ∂Bz/∂y) were detected. The direct current of the solar panel is visualized by calculating the composition of the two signal components, the phase angle, and mapping the DC current vector. The developed system can evaluate the uniformity of DC current distributions precisely and may be applicable for defect detection of solar panels.
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Decentralized Interleaving of Paralleled Dc-Dc Buck Converters: Preprint
DOE Office of Scientific and Technical Information (OSTI.GOV)
Johnson, Brian B; Rodriguez, Miguel; Sinha, Mohit
We present a decentralized control strategy that yields switch interleaving among parallel connected dc-dc buck converters without communication. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work represents the first fully decentralized strategy formore » switch interleaving of paralleled dc-dc buck converters.« less
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Torque ripple reduction of brushless DC motor based on adaptive input-output feedback linearization.
Shirvani Boroujeni, M; Markadeh, G R Arab; Soltani, J
2017-09-01
Torque ripple reduction of Brushless DC Motors (BLDCs) is an interesting subject in variable speed AC drives. In this paper at first, a mathematical expression for torque ripple harmonics is obtained. Then for a non-ideal BLDC motor with known harmonic contents of back-EMF, calculation of desired reference current amplitudes, which are required to eliminate some selected harmonics of torque ripple, are reviewed. In order to inject the reference harmonic currents to the motor windings, an Adaptive Input-Output Feedback Linearization (AIOFBL) control is proposed, which generates the reference voltages for three phases voltage source inverter in stationary reference frame. Experimental results are presented to show the capability and validity of the proposed control method and are compared with the vector control in Multi-Reference Frame (MRF) and Pseudo-Vector Control (P-VC) method results. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.
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Impact of public electric vehicle charging infrastructure
DOE Office of Scientific and Technical Information (OSTI.GOV)
Levinson, Rebecca S.; West, Todd H.
Our work uses market analysis and simulation to explore the potential of public charging infrastructure to spur US battery electric vehicle (BEV) sales, increase national electrified mileage, and lower greenhouse gas (GHG) emissions. By employing both scenario and parametric analysis for policy driven injection of public charging stations we find the following: (1) For large deployments of public chargers, DC fast chargers are more effective than level 2 chargers at increasing BEV sales, increasing electrified mileage, and lowering GHG emissions, even if only one DC fast charging station can be built for every ten level 2 charging stations. (2) Amore » national initiative to build DC fast charging infrastructure will see diminishing returns on investment at approximately 30,000 stations. (3) Some infrastructure deployment costs can be defrayed by passing them back to electric vehicle consumers, but once those costs to the consumer reach the equivalent of approximately 12¢/kWh for all miles driven, almost all gains to BEV sales and GHG emissions reductions from infrastructure construction are lost.« less
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High-pressure microhydraulic actuator
Mosier, Bruce P [San Francisco, CA; Crocker, Robert W [Fremont, CA; Patel, Kamlesh D [Dublin, CA
2008-06-10
Electrokinetic ("EK") pumps convert electric to mechanical work when an electric field exerts a body force on ions in the Debye layer of a fluid in a packed bed, which then viscously drags the fluid. Porous silica and polymer monoliths (2.5-mm O.D., and 6-mm to 10-mm length) having a narrow pore size distribution have been developed that are capable of large pressure gradients (250-500 psi/mm) when large electric fields (1000-1500 V/cm) are applied. Flowrates up to 200 .mu.L/min and delivery pressures up to 1200 psi have been demonstrated. Forces up to 5 lb-force at 0.5 mm/s (12 mW) have been demonstrated with a battery-powered DC-DC converter. Hydraulic power of 17 mW (900 psi@ 180 uL/min) has been demonstrated with wall-powered high voltage supplies. The force and stroke delivered by an actuator utilizing an EK pump are shown to exceed the output of solenoids, stepper motors, and DC motors of similar size, despite the low thermodynamic efficiency.
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Impact of public electric vehicle charging infrastructure
Levinson, Rebecca S.; West, Todd H.
2017-10-16
Our work uses market analysis and simulation to explore the potential of public charging infrastructure to spur US battery electric vehicle (BEV) sales, increase national electrified mileage, and lower greenhouse gas (GHG) emissions. By employing both scenario and parametric analysis for policy driven injection of public charging stations we find the following: (1) For large deployments of public chargers, DC fast chargers are more effective than level 2 chargers at increasing BEV sales, increasing electrified mileage, and lowering GHG emissions, even if only one DC fast charging station can be built for every ten level 2 charging stations. (2) Amore » national initiative to build DC fast charging infrastructure will see diminishing returns on investment at approximately 30,000 stations. (3) Some infrastructure deployment costs can be defrayed by passing them back to electric vehicle consumers, but once those costs to the consumer reach the equivalent of approximately 12¢/kWh for all miles driven, almost all gains to BEV sales and GHG emissions reductions from infrastructure construction are lost.« less
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Testing resonating vector strength: Auditory system, electric fish, and noise
NASA Astrophysics Data System (ADS)
Leo van Hemmen, J.; Longtin, André; Vollmayr, Andreas N.
2011-12-01
Quite often a response to some input with a specific frequency ν○ can be described through a sequence of discrete events. Here, we study the synchrony vector, whose length stands for the vector strength, and in doing so focus on neuronal response in terms of spike times. The latter are supposed to be given by experiment. Instead of singling out the stimulus frequency ν○ we study the synchrony vector as a function of the real frequency variable ν. Its length turns out to be a resonating vector strength in that it shows clear maxima in the neighborhood of ν○ and multiples thereof, hence, allowing an easy way of determining response frequencies. We study this "resonating" vector strength for two concrete but rather different cases, viz., a specific midbrain neuron in the auditory system of cat and a primary detector neuron belonging to the electric sense of the wave-type electric fish Apteronotus leptorhynchus. We show that the resonating vector strength always performs a clear resonance correlated with the phase locking that it quantifies. We analyze the influence of noise and demonstrate how well the resonance associated with maximal vector strength indicates the dominant stimulus frequency. Furthermore, we exhibit how one can obtain a specific phase associated with, for instance, a delay in auditory analysis.
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Effects of applied dc radial electric fields on particle transport in a bumpy torus plasma
NASA Technical Reports Server (NTRS)
Roth, J. R.
1978-01-01
The influence of applied dc radial electric fields on particle transport in a bumpy torus plasma is studied. The plasma, magnetic field, and ion heating mechanism are operated in steady state. Ion kinetic temperature is more than a factor of ten higher than electron temperature. The electric fields raise the ions to energies on the order of kilovolts and then point radially inward or outward. Plasma number density profiles are flat or triangular across the plasma diameter. It is suggested that the radial transport processes are nondiffusional and dominated by strong radial electric fields. These characteristics are caused by the absence of a second derivative in the density profile and the flat electron temperature profiles. If the electric field acting on the minor radius of the toroidal plasma points inward, plasma number density and confinement time are increased.
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LaDeau, Shannon L.; Leisnham, Paul T.; Biehler, Dawn; Bodner, Danielle
2013-01-01
Mosquito-vectored pathogens are responsible for devastating human diseases and are (re)emerging in many urban environments. Effective mosquito control in urban landscapes relies on improved understanding of the complex interactions between the ecological and social factors that define where mosquito populations can grow. We compared the density of mosquito habitat and pupae production across economically varying neighborhoods in two temperate U.S. cities (Baltimore, MD and Washington, DC). Seven species of mosquito larvae were recorded. The invasive Aedes albopictus was the only species found in all neighborhoods. Culex pipiens, a primary vector of West Nile virus (WNV), was most abundant in Baltimore, which also had more tire habitats. Both Culex and Aedes pupae were more likely to be sampled in neighborhoods categorized as being below median income level in each city and Aedes pupae density was also greater in container habitats found in these lower income neighborhoods. We infer that lower income residents may experience greater exposure to potential disease vectors and Baltimore residents specifically, were at greater risk of exposure to the predominant WNV vector. However, we also found that resident-reported mosquito nuisance was not correlated with our measured risk index, indicating a potentially important mismatch between motivation needed to engage participation in control efforts and the relative importance of control among neighborhoods. PMID:23583963
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Bowen, Anjanette K.; Weisser, John W.; Bergstedt, Roger A.; Famoye, Felix
2003-01-01
Four electrical factors that are used in pulsed DC electrofishing for larval sea lampreys (Petromyzon marinus) were evaluated in two laboratory studies to determine the optimal values to induce larval emergence over a range of water temperatures and conductivities. Burrowed larvae were exposed to combinations of pulsed DC electrical factors including five pulse frequencies, three pulse patterns, and two levels of duty cycle over a range of seven voltage gradients in two separate studies conducted at water temperatures of 10, 15, and 20°C and water conductivities of 25, 200, and 900 μS/cm. A four-way analysis of variance was used to determine significant (α = 0.05) influences of each electrical factor on larval emergence. Multiple comparison tests with Bonferroni adjustments were used to determine which values of each factor resulted in significantly higher emergence at each temperature and conductivity. Voltage gradient and pulse frequency significantly affected emergence according to the ANOVA model at each temperature and conductivity tested. Duty cycle and pulse pattern generally did not significantly influence the model. Findings suggest that a setting of 2.0 V/cm, 3 pulses/sec, 10% duty, and 2:2 pulse pattern seems the most promising in waters of medium conductivity and across a variety of temperatures. This information provides a basis for understanding larval response to pulsed DC electrofishing gear factors and identifies electrofisher settings that show promise to increase the efficiency of the gear during assessments for burrowed sea lamprey larvae.
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NASA Astrophysics Data System (ADS)
Pan, Zihe; Wang, Tianchang; Zhou, Yikang; Zhao, Boxin
2016-12-01
Electrically conductive and superoleophobic micropillars have been developed through the construction of biomimetic micropillars using Ag-filled epoxy composites and the incorporation of FDTS on the micropillar surface. These micropillars are found to be superoleophobic with an oil contact angle of 140°, demonstrating excellent self-cleaning properties. The conductivity of micropillars allows for the Joule-heating effect to actively reduce the adhesion and even unfreeze the frozen oil droplets by passing electrical current. Electrical resistance of the composite micropillars was modulated by two orders of magnitudes by varying the contents of Ag flakes from 45 wt% to 65 wt%. The effectiveness of conductive micropillars for surface un-freezing was investigated by applying DC current to decrease the adhesion strength of frozen oil droplets on surfaces. The results showed a pronounced reduction of frozen oil adhesion force by 60% when the resistance increased from 7.5 Ω to 877 Ω after applying DC current for 2 min. By continuously applying DC current for 3 min, the frozen oil adhesion decreased to 0.05 N, reaching zero when the surface was heated up to -10 °C after applying DC current for 5 min. In contrast, when the droplet was heated up to -5 °C by hot air, there is still a substantial force of adhesion. The research findings demonstrate the use of constructing conductive-superoleophobic composite micropillars at surface for eliminating the frozen oil from surfaces at low temperatures.
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Photovoltaic dependence of photorefractive grating on the externally applied dc electric field
NASA Astrophysics Data System (ADS)
Maurya, M. K.; Yadav, R. A.
2013-04-01
Photovoltaic dependence of photorefractive grating (i.e., space-charge field and phase-shift of the index grating) on the externally applied dc electric field in photovoltaic-photorefractive materials has been investigated. The influence of photovoltaic field (EPhN), diffusion field and carrier concentration ratio r (donor/acceptor impurity concentration ratio) on the space-charge field (SCF) and phase-shift of the index grating in the presence and absence of the externally applied dc electric field have also been studied in details. Our results show that, for a given value of EPhN and r, the magnitude of the SCF and phase-shift of the index grating can be enhanced significantly by employing the lower dc electric field (EON<10) across the photovoltaic-photorefractive crystal and higher value of diffusion field (EDN>40). Such an enhancement in the magnitude of the SCF and phase-shift of the index grating are responsible for the strongest beam coupling in photovoltaic-photorefractive materials. This sufficiently strong beam coupling increases the two-beam coupling gain that may be exceed the absorption and reflection losses of the photovoltaic-photorefractive sample, and optical amplification can occur. The higher value of optical amplification in photovoltaic-photorefractive sample is required for the every applications of photorefractive effect so that technology based on the photorefractive effect such as holographic storage devices, optical information processing, acousto-optic tunable filters, gyro-sensors, optical modulators, optical switches, photorefractive-photovoltaic solitons, biomedical applications, and frequency converters could be improved.
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Northeastern Summer Electricity Market Alert
2013-01-01
The National Weather Service declared an excessive-heat warning for much of the Mid-Atlantic and northeastern United States, including major electric markets covering Philadelphia, Boston, Washington, D.C., and New York City. This report highlights the wholesale electricity market activity occurring in response to the higher-than-normal electricity demand caused by the heat wave.
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NASA Astrophysics Data System (ADS)
Bechstein, S.; Petsche, F.; Scheiner, M.; Drung, D.; Thiel, F.; Schnabel, A.; Schurig, Th
2006-06-01
Recently, we have developed a family of dc superconducting quantum interference device (SQUID) readout electronics for several applications. These electronics comprise a low-noise preamplifier followed by an integrator, and an analog SQUID bias circuit. A highly-compact low-power version with a flux-locked loop bandwidth of 0.3 MHz and a white noise level of 1 nV/√Hz was specially designed for a 304-channel low-Tc dc SQUID vector magnetometer, intended to operate in the new Berlin Magnetically Shielded Room (BMSR-2). In order to minimize the space needed to mount the electronics on top of the dewar and to minimize the power consumption, we have integrated four electronics channels on one 3 cm × 10 cm sized board. Furthermore we embedded the analog components of these four channels into a digitally controlled system including an in-system programmable microcontroller. Four of these integrated boards were combined to one module with a size of 4 cm × 4 cm × 16 cm. 19 of these modules were implemented, resulting in a total power consumption of about 61 W. To initialize the 304 channels and to service the system we have developed software tools running on a laptop computer. By means of these software tools the microcontrollers are fed with all required data such as the working points, the characteristic parameters of the sensors (noise, voltage swing), or the sensor position inside of the vector magnetometer system. In this paper, the developed electronics including the software tools are described, and first results are presented.
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Power And Propulsion Systems For Mobile Robotic Applications
NASA Astrophysics Data System (ADS)
Layuan, Li; Haiming, Zou
1987-02-01
Choosing the best power and propulsion systems for mobile robotic land vehicle applications requires consideration of technologies. The electric power requirements for onboard electronic and auxiliary equipment include 110/220 volt 60 Hz ac power as well as low voltage dc power. Weight and power are saved by either direct dc power distribution, or high frequency (20 kHz) ac power distribution. Vehicle control functions are performed electronically but steering, braking and traction power may be distributed electrically, mechanically or by fluid (hydraulic) means. Electric drive is practical, even for small vehicles, provided that advanced electric motors are used. Such electric motors have demonstrated power densities of 3.1 kilowatts per kilogram with devices in the 15 kilowatt range. Electric motors have a lower torque, but higher power density as compared to hydraulic or mechanical transmission systems. Power density being comparable, electric drives were selected to best meet the other requirements for robotic vehicles. Two robotic vehicle propulsion system designs are described to illustrate the implementation of electric drive over a vehicle size range of 250-7500 kilograms.
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NASA Technical Reports Server (NTRS)
Bates, Lisa B.; Young, David T.
2012-01-01
This paper describes recent developmental testing to verify the integration of a developmental electromechanical actuator (EMA) with high rate lithium ion batteries and a cross platform extensible controller. Testing was performed at the Thrust Vector Control Research, Development and Qualification Laboratory at the NASA George C. Marshall Space Flight Center. Electric Thrust Vector Control (ETVC) systems like the EMA may significantly reduce recurring launch costs and complexity compared to heritage systems. Electric actuator mechanisms and control requirements across dissimilar platforms are also discussed with a focus on the similarities leveraged and differences overcome by the cross platform extensible common controller architecture.
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Polarization ellipse and Stokes parameters in geometric algebra.
Santos, Adler G; Sugon, Quirino M; McNamara, Daniel J
2012-01-01
In this paper, we use geometric algebra to describe the polarization ellipse and Stokes parameters. We show that a solution to Maxwell's equation is a product of a complex basis vector in Jackson and a linear combination of plane wave functions. We convert both the amplitudes and the wave function arguments from complex scalars to complex vectors. This conversion allows us to separate the electric field vector and the imaginary magnetic field vector, because exponentials of imaginary scalars convert vectors to imaginary vectors and vice versa, while exponentials of imaginary vectors only rotate the vector or imaginary vector they are multiplied to. We convert this expression for polarized light into two other representations: the Cartesian representation and the rotated ellipse representation. We compute the conversion relations among the representation parameters and their corresponding Stokes parameters. And finally, we propose a set of geometric relations between the electric and magnetic fields that satisfy an equation similar to the Poincaré sphere equation.
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Investigation of the Feasibility of a Superconducting Self-Healing DC Grid on a LNG Carrier
2015-06-21
art in High Temperature Superconductor technology is reviewed and an analytical approach of Superconducting DC Power Distribution on a power... Superconductors . I. INTRODUCTION During recent years, the usage of electrical power on- board vessels has grown exponentially. This fact, led...grid. When carrying DC current superconductors are perfectly lossless regardless of the cable length and the power rating of the line [1]. Also
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NASA Technical Reports Server (NTRS)
Bradley, William; Bird, Ross; Eldred, Dennis; Zook, Jon; Knowles, Gareth
2013-01-01
This work involved developing spacequalifiable switch mode DC/DC power supplies that improve performance with fewer components, and result in elimination of digital components and reduction in magnetics. This design is for missions where systems may be operating under extreme conditions, especially at elevated temperature levels from 200 to 300 degC. Prior art for radiation-tolerant DC/DC converters has been accomplished utilizing classical magnetic-based switch mode converter topologies; however, this requires specific shielding and component de-rating to meet the high-reliability specifications. It requires complex measurement and feedback components, and will not enable automatic re-optimization for larger changes in voltage supply or electrical loading condition. The innovation is a switch mode DC/DC power supply that eliminates the need for processors and most magnetics. It can provide a well-regulated voltage supply with a gain of 1:100 step-up to 8:1 step down, tolerating an up to 30% fluctuation of the voltage supply parameters. The circuit incorporates a ceramic core transformer in a manner that enables it to provide a well-regulated voltage output without use of any processor components or magnetic transformers. The circuit adjusts its internal parameters to re-optimize its performance for changes in supply voltage, environmental conditions, or electrical loading at the output
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Takahashi, Shota; Asada, Atsushi; Matsuo, Minako; Kishikawa, Kenta; Mizuno, Akira
2015-01-01
Electroporation is the most widely used transfection method for delivery of cell-impermeable molecules into cells. We developed a novel gene transfection method, water-in-oil (W/O) droplet electroporation, using dielectric oil and an aqueous droplet containing mammalian cells and transgene DNA. When a liquid droplet suspended between a pair of electrodes in dielectric oil is exposed to a DC electric field, the droplet moves between the pair of electrodes periodically and droplet deformation occurs under the intense DC electric field. During electrostatic manipulation of the droplet, the local intense electric field and instantaneous short circuit via the droplet due to droplet deformation facilitate gene transfection. This method has several advantages over conventional transfection techniques, including co-transfection of multiple transgene DNAs into even as few as 103 cells, transfection into differentiated neural cells, and the capable establishment of stable cell lines. In addition, there have been improvements in W/O droplet electroporation electrodes for disposable 96-well plates making them suitable for concurrent performance without thermal loading by a DC electric field. This technique will lead to the development of cell transfection methods for novel regenerative medicine and gene therapy. PMID:26649904
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Thermoelectric as recovery and harvesting of waste heat from portable generator
NASA Astrophysics Data System (ADS)
Mustafa, S. N.; Kamarrudin, N. S.; Hashim, M. S. M.; Bakar, S. A.; Razlan, Z. M.; Harun, A.; Ibrahim, I.; Faizi, M. K.; Saad, M. A. M.; Zunaidi, I.; Wan, W. K.; Desa, H.
2017-10-01
Generation of waste heat was ineluctable especially during energy producing process. Waste heat falls into low temperature grade make it complicated to utilize. Thermoelectric generator (TEG) offers opportunity to harvest any temperature grade heat into useful electricity. This project is covered about recovery and utilizing waste heat from portable electric generator by using a TEG which placed at exhaust surface. Temperature difference at both surfaces of TEG was enhanced with supplying cold air from a wind blower. It is found that, even at low air speed, the TEG was successfully produced electricity with aid from DC-DC booster. Results shows possibility to harvest low temperature grade heat and still exist areas for continual improvement.
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NASA Astrophysics Data System (ADS)
Asami, Noriaki; King, Julien; Monk, Martin
2000-02-01
This paper looks at the familiar problem of students' understanding of elementary electrical circuits from a much neglected point of view. It is conjectured that the patterning commonly found in students' ideas might have its roots in the cognitive processing with which students operate their mental models of d.c. electrical circuits. The data are new and come from Japanese 10-11 year olds living in the UK. Progressive analysis of these students' answers to a six item test shows that the percentage of students operating particular mental models, following tuition, matches the percentages one might expect from a knowledge of their cognitive processing.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Ram, Mast, E-mail: mastram1999@yahoo.com; Bala, Kanchan; Sharma, Hakikat
In the present study, nanoparticles of Fe doped zinc oxide (ZnO) [Zn{sub 1-x}Fe{sub x}O where x=0.0, 0.01, 0.02, 0.03 and 0.05] were prepared by cost effective solution combustion method. The powder X-ray diffractometry confirms the formation of single phase wurtzite structure. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were used to investigate the micrsostructure of Fe-doped ZnO nanoparticles. The DC electrical conductivity was found to increase with temperature and measurement was carried out in the temperature range of 300-473K. DC electrical conductivity increases with temperature and decreases with Fe doping concentration.
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NASA Astrophysics Data System (ADS)
Aly, Said A.; Farag, Karam S. I.; Atya, Magdy A.; Badr, Mohamed A. M.
2018-06-01
A joint multi-spacing electromagnetic-terrain conductivity meter and DC-resistivity horizontal profiling survey was conducted at the anticipated eastern extensional area of the 15th-of-May City, southeastern Cairo, Egypt. The main objective of the survey was to highlight the applicability, efficiency, and reliability of utilizing such non-invasive surface techniques in a field like geologic mapping, and hence to image both the vertical and lateral electrical resistivity structures of the subsurface bedrock. Consequently, a total of reliable 6 multi-spacing electromagnetic-terrain conductivity meter and 7 DC-resistivity horizontal profiles were carried out between August 2016 and February 2017. All data sets were transformed-inverted extensively and consistently in terms of two-dimensional (2D) electrical resistivity smoothed-earth models. They could be used effectively and inexpensively to interpret the area's bedrock geologic sequence using the encountered consecutive electrically resistive and conductive anomalies. Notably, the encountered subsurface electrical resistivity structures, below all surveying profiles, are correlated well with the mapped geological faults in the field. They even could provide a useful understanding of their faulting fashion. Absolute resistivity values were not necessarily diagnostic, but their vertical and lateral variations could provide more diagnostic information about the layer lateral extensions and thicknesses, and hence suggested reliable geo-electric earth models. The study demonstrated that a detailed multi-spacing electromagnetic-terrain conductivity meter and DC-resistivity horizontal profiling survey can help design an optimal geotechnical investigative program, not only for the whole eastern extensional area of the 15th-of-May City, but also for the other new urban communities within the Egyptian desert.
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NASA Technical Reports Server (NTRS)
Edie, P. C.
1981-01-01
Straight and chopped DC motor performances for a Reliance EV-250AT motor with an EV-1 controller were examined. Effects of motor temperature and operating voltage are shown. It is found that the maximum motor efficiency is approximately 85% at low operating temperatures in the straight DC mode. Chopper efficiency is 95% under all operating conditions. For equal speeds, the motor operated in the chopped mode develops slightly more torque and draws more current than it does in the straight DC mode.
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1976-02-01
Transition from Specular Reflection to Diffuse Scattering. . . 10 Composition of the Electric-Field Vector as Seen at the Radar...r t (16) R • FIGURE P COMPOSITION OF THE ELECTRIC-FIELD VECTOR AS SEEN AT THE RADAR, R, IN FIG. 2. The electric field at the radar, E, is the sum...wavelengths in the VHP and UHF ranges even subsurface characteristics can be important. So in a field experiment one must be careful to measure
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Electric fields and vector potentials of thin cylindrical antennas
NASA Astrophysics Data System (ADS)
King, Ronold W. P.
1990-09-01
The vector potential and electric field generated by the current in a center-driven or parasitic dipole antenna that extends from z = -h to z = h are investigated for each of the several components of the current. These include sin k(h - absolute value of z), sin k (absolute value of z) - sin kh, cos kz - cos kh, and cos kz/2 - cos kh/2. Of special interest are the interactions among the variously spaced elements in parallel nonstaggered arrays. These depend on the mutual vector potentials. It is shown that at a radial distance rho approximately = h and in the range z = -h to h, the vector potentials due to all four components become alike and have an approximately plane-wave form. Simple approximate formulas for the electric fields and vector potentials generated by each of the four distributions are derived and compared with the exact results. The application of the new formulas to large arrays is discussed.
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MHD thrust vectoring of a rocket engine
NASA Astrophysics Data System (ADS)
Labaune, Julien; Packan, Denis; Tholin, Fabien; Chemartin, Laurent; Stillace, Thierry; Masson, Frederic
2016-09-01
In this work, the possibility to use MagnetoHydroDynamics (MHD) to vectorize the thrust of a solid propellant rocket engine exhaust is investigated. Using a magnetic field for vectoring offers a mass gain and a reusability advantage compared to standard gimbaled, elastomer-joint systems. Analytical and numerical models were used to evaluate the flow deviation with a 1 Tesla magnetic field inside the nozzle. The fluid flow in the resistive MHD approximation is calculated using the KRONOS code from ONERA, coupling the hypersonic CFD platform CEDRE and the electrical code SATURNE from EDF. A critical parameter of these simulations is the electrical conductivity, which was evaluated using a set of equilibrium calculations with 25 species. Two models were used: local thermodynamic equilibrium and frozen flow. In both cases, chlorine captures a large fraction of free electrons, limiting the electrical conductivity to a value inadequate for thrust vectoring applications. However, when using chlorine-free propergols with 1% in mass of alkali, an MHD thrust vectoring of several degrees was obtained.
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Effect of an alternating current electric field on Co(OH)2 periodic precipitation
NASA Astrophysics Data System (ADS)
Karam, Tony; Sultan, Rabih
2013-02-01
The present paper studies the effect of an alternating current (AC) electric field on Co(OH)2 Liesegang patterns. In the presence of an AC electric field, the band spacing increases with spacing number, but reaches a plateau at large spacing (or band) numbers. The band spacing increases with applied AC voltage, but to a much lesser extent than the effect of a DC electric field under the same applied voltage [see R. Sultan, R. Halabieh, Chem. Phys. Lett. 332 (2000) 331][1]. At low enough applied voltage, the band spacing increases with frequency. At higher voltages, the band spacing becomes independent of the field frequency. The effect of concentration of the inner electrolyte (Co2+), exactly opposes that observed under DC electric field; i.e., the band spacing decreases with increasing concentration. The dynamics were shown to be governed by a competitive scenario between the diffusion gradient and the alternating current electric field factor.
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Reduced energy consumption by massive thermoelectric waste heat recovery in light duty trucks
NASA Astrophysics Data System (ADS)
Magnetto, D.; Vidiella, G.
2012-06-01
The main objective of the EC funded HEATRECAR project is to reduce the energy consumption and curb CO2 emissions of vehicles by massively harvesting electrical energy from the exhaust system and re-use this energy to supply electrical components within the vehicle or to feed the power train of hybrid electrical vehicles. HEATRECAR is targeting light duty trucks and focuses on the development and the optimization of a Thermo Electric Generator (TEG) including heat exchanger, thermoelectric modules and DC/DC converter. The main objective of the project is to design, optimize and produce a prototype system to be tested on a 2.3l diesel truck. The base case is a Thermo Electric Generator (TEG) producing 1 KWel at 130 km/h. We present the system design and estimated output power from benchmark Bi2Te3 modules. We discuss key drivers for the optimization of the thermal-to-electric efficiency, such as materials, thermo-mechanical aspects and integration.
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Cascade of kinetic energy and scalar variance in DC electrokinetic turbulence
NASA Astrophysics Data System (ADS)
Zhao, Wei; Wang, Guiren
2017-11-01
Turbulent flow can be generated by DC electrokinetic (EK) force based on the electric conductivity and permittivity variations in fluids, as have been demonstrated by Varshney et al (2016), where a -1.4 slope of velocity power spectrum is observed. Here, we theoretically found the scaling exponents of velocity and scalar structures in the electric-body-force (EBF) dominant subregion of DC EK turbulence were 2/5 (equivalent to the -7/5 slope of velocity power spectrum) and 4/5 respectively. The theory perfectly explains the experimental results of Varshney et al. (2016). Based on Kármán-Howarth equation with forcing terms, the energy cascade process of DC EK turbulence was also investigated. Depending on the electric Rayleigh number (Rae) , two different energy cascade processes may happen. When Rae is small, the kinetic energy cascades along inertial subregion and EBF dominant subregion in sequence, before it is dissipated by fluid viscosity. When Rae is sufficiently large, the inertial subregion may be absent with EBF dominant subregion left. This investigation is very important on understand EK turbulence, which could be widely existed in nature and applied in engineerings. The work was supported by NSFC (11672229), and NSF (CAREER CBET-0954977 and MRI CBET-1040227).
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Dolan, C.R.; Miranda, L.E.; Henry, T.B.
2002-01-01
Continuous direct current (DC) and pulsed DC (PDC) of varying frequency and pulse period are commonly used to immobilize and collect crappies Pomoxis spp. in freshwater. However, little information is available about the minimum electrical-setting thresholds required for immobilization or how the settings relate to incidence of injury. We investigated the effect of increasing power densities on the immobilization and injury of black crappies P. nigromaculatus (average total length = 154 mm) treated with DC and various PDC settings. Forced swimming toward the electrodes was observed in black crappies exposed to DC, but that was less apparent for PDC. The minimum peak power densities required to immobilize black crappies ranged from 0.10 to 6.5 mW/cm3 and depended on pulse frequency and period. The incidence of hemorrhaging ranged from 0% to 50% and that of spinal damage from 9% to 45%. However, the severity of injury also depended on pulse frequency and period. No fish suffered mortality at or below the immobilization thresholds, but mortality ranged from 0% to 15% at settings above the thresholds. Mortality was observed with PDC settings of 15 Hz only. Fish that were tetanized following electrical treatment were more prone to injury than those that exhibited narcosis.
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NASA Astrophysics Data System (ADS)
Farag, Karam S. I.; Abd El-Aal, Mohamed H.; Garamoon, Hassan K. F.
2018-07-01
A joint azimuthal very low frequency-electromagnetic (VLF-EM) and DC-resistivity sounding survey was conducted at the new Ain Shams university campus in Al-Obour city, northwest of Cairo, Egypt. The main objective of the survey was to highlight the applicability and reliability of such non-invasive surface techniques in mapping and monitoring both the vertical and lateral electrical conductivity structures of waterlogged areas, by subterraneous water accumulations, at the campus site. Consequently, a total of 743 azimuthal VLF-EM and 4 DC-resistivity soundings were carried out in June, 2011, 2012 and 2013. The data were interpreted extensively and consistently in terms of two-dimensional (2D) transformed EM equivalent current-density and stitched inverted electrical resistivity models, without using any geological a-priori information. They could be used effectively to image the local anomalous lower electrical resistivity (higher EM equivalent current-density) structures and their near-surface spreading with time, due to the excessive accumulations of subterraneous water at the campus site. The study demonstrated that a regional azimuthal VLF-EM and DC-resistivity sounding survey could help design an optimal dewatering program for the whole city, at greatly reduced execution time.
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Chhabra, Arvind; Chakraborty, Nityo G.; Mukherji, Bijay
2008-01-01
Dendritic cells (DC) present antigenic epitopes to and activate T cells. They also polarize the ensuing T cell response to Th1 or Th2 type response, depending on their cytokine production profile. For example, IL-12 producing DC generate Th1 type T cell response whereas IL-10 producing DC is usually tolerogenic. Different strategies -- such as the use of cytokines and anti-cytokine antibodies, dominant negative forms of protein, anti-sense RNA etc. -- have been employed to influence the cytokine synthetic profile of DC as well as to make DC more immunogenic. Utilizing GFP expressing recombinant adenoviruses in association with lipid-mediated transfection of siRNA, we have silenced the endogenous IL-10 gene in DC. We show that IL-10 gene silenced DC produce more IL-12 and also generates a better cytolytic T cell response against the human melanoma associated epitope, MART-127−35, in-vitro. We also show that the GFP expressing adenoviral vector can be used to optimize the parameters for siRNA delivery in primary cells and show that RNA interference methodology can efficiently knock-down virus encoded genes transcribed at very high multiplicity of infection in DC. PMID:18249038
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Aboughalma, Hanssan; Bi, Ran; Schlaak, Michael
2008-07-01
The use of a combination of electrokinetic remediation and phytoremediation to decontaminate soil polluted with heavy metals has been demonstrated in a laboratory-scale experiment. Potato tubers were planted in plastic vessels filled with Zn, Pb, Cu and Cd contaminated soil and grown in a greenhouse. Three of these vessels were treated with direct current electric field (DC), three with alternative current (AC) and three remained untreated as control vessels. The soil pH varied from anode to cathode with a minimum of pH 3 near the anode and a maximum of pH 8 near the cathode in the DC treated soil profile. There was an accumulation of Zn, Cu and Cd at about 12 cm distance from anode when soil pH was 5 in the DC treated soil profile. There was no significant metal redistribution and pH variation between anode and cathode in the AC soil profile. The biomass production of the plants was 72% higher under AC treatment and 27% lower under DC treatment compared to the control. Metal accumulation was generally higher in the plant roots treated with electrical fields than the control. The overall metal uptake in plant shoots was lower under DC treatment compared to AC treatment and control, although there was a higher accumulation of Zn and Cu in the plant roots treated with electrical fields. The Zn uptake in plant shoots under AC treatment was higher compared to the control and DC treatment. Zn and Cu accumulation in the plant roots under AC and DC treatment was similar, and both were higher comparing to control. Cd content in plant roots under all three treatments was found to be higher than that in the soil. The Pb accumulation in the roots and the uptake into the shoots was lower compared to its content in the soil.
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"Long life" DC brush motor for use on the Mars surveyor program
NASA Technical Reports Server (NTRS)
Braun, David; Noon, Don
1998-01-01
DC brush motors have several qualities which make them very attractive for space flight applications. Their mechanical commutation is simple and lightweight, requiring no external sensing and control in order to function properly. They are extremely efficient in converting electrical energy into mechanical energy. Efficiencies over 80% are not uncommon, resulting in high power throughput to weight ratios. However, the inherent unreliability and short life of sliding electrical contacts, especially in vacuum, have driven previous programs to utilize complex brushless DC or the less efficient stepper motors. The Mars Surveyor Program (MSP'98) and the Shuttle Radar Topography Mission (SRTM) have developed a reliable "long life" brush type DC motor for operation in low temperature, low pressure CO2 and N2, utilizing silver-graphite brushes. The original intent was to utilize this same motor for SRTM's space operation, but the results thus far have been unsatisfactory in vacuum. This paper describes the design, test, and results of this development.
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NASA Astrophysics Data System (ADS)
Kheirabadi, Narjes; McCann, Edward; Fal'ko, Vladimir I.
2018-02-01
We model the magnetic ratchet effect in bilayer graphene in which a dc electric current is produced by an ac electric field of frequency ω in the presence of a steady in-plane magnetic field and inversion-symmetry breaking. In bilayer graphene, the ratchet effect is tunable by an external metallic gate which breaks inversion symmetry. For zero in-plane magnetic field, we show that trigonal warping and inversion-symmetry breaking are able to produce a large dc valley current, but not a nonzero total dc charge current. For the magnetic ratchet in a tilted magnetic field, the perpendicular field component induces cyclotron motion with frequency ωc and we find that the dc current displays cyclotron resonance at ωc=ω , although this peak in the current is actually smaller than its value at ωc=0 . Second harmonic generation, however, is greatly enhanced by resonances at ωc=ω and ωc=2 ω for which the current is generally much larger than at ωc=0 .
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A New Supercapacitor and Li-ion Battery Hybrid System for Electric Vehicle in ADVISOR
NASA Astrophysics Data System (ADS)
Peng, Xiao; Shuhai, Quan; Changjun, Xie
2017-02-01
The supercapacitor (SC) and Li-ion battery(BT) hybrid energy storage system(HESS) electric vehicle(EV) is gaining universal attention. The topology is of importance for the SC/BT HESS. A new SC/BT topology HESS with a rule-based energy management strategy for EV was proposed. The BT pack is connected directly to the DC link via a controlled switch. The SC pack is connected to the DC link via a controlled switch. A uni-directional DC/DC converter is connected between the SC pack and the BT pack. The braking regeneration energy is all harvested by the SC pack. The output power of BT pack is limited. The different SC/BT configurations with varied BT maximum Ah capacity factor and SC maximum capacity factor are simulated in ADVISOR. Simulation results show that BT maximum Ah capacity factor has little impact on vehicle acceleration performance and maximum speed. SC maximum capacity factor has significant impact on vehicle acceleration performance and maximum speed. The fuel economy isn’t affected.
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AC power generation from microbial fuel cells
NASA Astrophysics Data System (ADS)
Lobo, Fernanda Leite; Wang, Heming; Forrestal, Casey; Ren, Zhiyong Jason
2015-11-01
Microbial fuel cells (MFCs) directly convert biodegradable substrates to electricity and carry good potential for energy-positive wastewater treatment. However, the low and direct current (DC) output from MFC is not usable for general electronics except small sensors, yet commercial DC-AC converters or inverters used in solar systems cannot be directly applied to MFCs. This study presents a new DC-AC converter system for MFCs that can generate alternating voltage in any desired frequency. Results show that AC power can be easily achieved in three different frequencies tested (1, 10, 60 Hz), and no energy storage layer such as capacitors was needed. The DC-AC converter efficiency was higher than 95% when powered by either individual MFCs or simple MFC stacks. Total harmonic distortion (THD) was used to investigate the quality of the energy, and it showed that the energy could be directly usable for linear electronic loads. This study shows that through electrical conversion MFCs can be potentially used in household electronics for decentralized off-grid communities.
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Zhang, Peng; Lau, Y. Y.
2016-01-01
Laser-driven ultrafast electron emission offers the possibility of manipulation and control of coherent electron motion in ultrashort spatiotemporal scales. Here, an analytical solution is constructed for the highly nonlinear electron emission from a dc biased metal surface illuminated by a single frequency laser, by solving the time-dependent Schrödinger equation exactly. The solution is valid for arbitrary combinations of dc electric field, laser electric field, laser frequency, metal work function and Fermi level. Various emission mechanisms, such as multiphoton absorption or emission, optical or dc field emission, are all included in this single formulation. The transition between different emission processes is analyzed in detail. The time-dependent emission current reveals that intense current modulation may be possible even with a low intensity laser, by merely increasing the applied dc bias. The results provide insights into the electron pulse generation and manipulation for many novel applications based on ultrafast laser-induced electron emission. PMID:26818710
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NASA Technical Reports Server (NTRS)
Bever, R. S.
1984-01-01
Nondestructive high voltage test techniques (mostly electrical methods) are studied to prevent total or catastrophic breakdown of insulation systems under applied high voltage in space. Emphasis is on the phenomenon of partial breakdown or partial discharge (P.D.) as a symptom of insulation quality, notably partial discharge testing under D.C. applied voltage. Many of the electronic parts and high voltage instruments in space experience D.C. applied stress in service, and application of A.C. voltage to any portion thereof would be prohibited. Suggestions include: investigation of the ramp test method for D.C. partial discharge measurements; testing of actual flight-type insulation specimen; perfect plotting resin samples with controlled defects for test; several types of plotting resins and recommendations of the better ones from the electrical characteristics; thermal and elastic properties are also considered; testing of commercial capaciters; and approximate acceptance/rejection/rerating criteria for sample test elements for space use, based on D.C. partial discharge.
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The Role of Direct Current Electric Field-Guided Stem Cell Migration in Neural Regeneration.
Yao, Li; Li, Yongchao
2016-06-01
Effective directional axonal growth and neural cell migration are crucial in the neural regeneration of the central nervous system (CNS). Endogenous currents have been detected in many developing nervous systems. Experiments have demonstrated that applied direct current (DC) electric fields (EFs) can guide axonal growth in vitro, and attempts have been made to enhance the regrowth of damaged spinal cord axons using DC EFs in in vivo experiments. Recent work has revealed that the migration of stem cells and stem cell-derived neural cells can be guided by DC EFs. These studies have raised the possibility that endogenous and applied DC EFs can be used to direct neural tissue regeneration. Although the mechanism of EF-directed axonal growth and cell migration has not been fully understood, studies have shown that the polarization of cell membrane proteins and the activation of intracellular signaling molecules are involved in the process. The application of EFs is a promising biotechnology for regeneration of the CNS.
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Liquid Droplet Dynamics in Gravity Compensating High Magnetic Field
NASA Technical Reports Server (NTRS)
Bojarevics, V.; Easter, S.; Pericleous, K.
2012-01-01
Numerical models are used to investigate behavior of liquid droplets suspended in high DC magnetic fields of various configurations providing microgravity-like conditions. Using a DC field it is possible to create conditions with laminar viscosity and heat transfer to measure viscosity, surface tension, electrical and thermal conductivities, and heat capacity of a liquid sample. The oscillations in a high DC magnetic field are quite different for an electrically conducting droplet, like liquid silicon or metal. The droplet behavior in a high magnetic field is the subject of investigation in this paper. At the high values of magnetic field some oscillation modes are damped quickly, while others are modified with a considerable shift of the oscillating droplet frequencies and the damping constants from the non-magnetic case.
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Decentralized Interleaving of Paralleled Dc-Dc Buck Converters
DOE Office of Scientific and Technical Information (OSTI.GOV)
Johnson, Brian B; Rodriguez, Miguel; Sinha, Mohit
We present a decentralized control strategy that yields switch interleaving among parallel-connected dc-dc buck converters. The proposed method is based on the digital implementation of the dynamics of a nonlinear oscillator circuit as the controller. Each controller is fully decentralized, i.e., it only requires the locally measured output current to synthesize the pulse width modulation (PWM) carrier waveform and no communication between different controllers is needed. By virtue of the intrinsic electrical coupling between converters, the nonlinear oscillator-based controllers converge to an interleaved state with uniform phase-spacing across PWM carriers. To the knowledge of the authors, this work presents themore » first fully decentralized strategy for switch interleaving in paralleled dc-dc buck converters.« less
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Holography and thermalization in optical pump-probe spectroscopy
NASA Astrophysics Data System (ADS)
Bagrov, A.; Craps, B.; Galli, F.; Keränen, V.; Keski-Vakkuri, E.; Zaanen, J.
2018-04-01
Using holography, we model experiments in which a 2 +1 D strange metal is pumped by a laser pulse into a highly excited state, after which the time evolution of the optical conductivity is probed. We consider a finite-density state with mildly broken translation invariance and excite it by oscillating electric field pulses. At zero density, the optical conductivity would assume its thermalized value immediately after the pumping has ended. At finite density, pulses with significant dc components give rise to slow exponential relaxation, governed by a vector quasinormal mode. In contrast, for high-frequency pulses the amplitude of the quasinormal mode is strongly suppressed, so that the optical conductivity assumes its thermalized value effectively instantaneously. This surprising prediction may provide a stimulus for taking up the challenge to realize these experiments in the laboratory. Such experiments would test a crucial open question faced by applied holography: are its predictions artifacts of the large N limit or do they enjoy sufficient UV independence to hold at least qualitatively in real-world systems?
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Ponchel, F., E-mail: freddy.ponchel@univ-valenciennes.fr; Rémiens, D.; Sama, N.
2014-12-28
350 nm-thick Perovskite PbZr{sub 0.54}Ti{sub 0.46}O{sub 3} (PZT) thin films were deposited on Al{sub 2}O{sub 3} substrates by sputtering with and without an additional 10-nm-thick TiO{sub x} buffer layer. X-ray diffraction patterns showed that in presence of TiO{sub x} buffer layer, PZT film was highly oriented along the (111) direction film, whereas the unbuffered, counterpart was polycrystalline. A full wave electromagnetic analysis using a vector finite element method was performed to determine the tunability and the complex permittivity up to 67 GHz. A comparison between the electromagnetic analysis and Cole-Cole relaxation model was proposed. Through an original study of the relaxation timemore » as a function of the electric field, values, such as 2 ps and 0.6 ps, were estimated for E{sub DC} = 0 kV/cm and 235 kV/cm, respectively, and in both cases (111)-PZT and polycrystalline-PZT. The distribution of relaxation times is found to be larger for (111)-PZT film, which is probably related to the film microstructure.« less
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NASA Astrophysics Data System (ADS)
Kaushik, Deepak Kumar; Kumar, K. Uday; Subrahmanyam, A.
2017-01-01
Tin doped indium oxide (ITO) thin films are being used extensively as transparent conductors in several applications. In the present communication, we report the electrical transport in DC magnetron sputtered ITO thin films (prepared at 300 K and subsequently annealed at 673 K in vacuum for 60 minutes) in low temperatures (25-300 K). The low temperature Hall effect and resistivity measurements reveal that the ITO thin films are moderately dis-ordered (kFl˜1; kF is the Fermi wave vector and l is the electron mean free path) and degenerate semiconductors. The transport of charge carriers (electrons) in these disordered ITO thin films takes place via the de-localized states. The disorder effects lead to the well-known `metal-insulator transition' (MIT) which is observed at 110 K in these ITO thin films. The MIT in ITO thin films is explained by the quantum correction to the conductivity (QCC); this approach is based on the inclusion of quantum-mechanical interference effects in Boltzmann's expression of the conductivity of the disordered systems. The insulating behaviour observed in ITO thin films below the MIT temperature is attributed to the combined effect of the weak localization and the electron-electron interactions.
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An improved fault-tolerant control scheme for PWM inverter-fed induction motor-based EVs.
Tabbache, Bekheïra; Benbouzid, Mohamed; Kheloui, Abdelaziz; Bourgeot, Jean-Matthieu; Mamoune, Abdeslam
2013-11-01
This paper proposes an improved fault-tolerant control scheme for PWM inverter-fed induction motor-based electric vehicles. The proposed strategy deals with power switch (IGBTs) failures mitigation within a reconfigurable induction motor control. To increase the vehicle powertrain reliability regarding IGBT open-circuit failures, 4-wire and 4-leg PWM inverter topologies are investigated and their performances discussed in a vehicle context. The proposed fault-tolerant topologies require only minimum hardware modifications to the conventional off-the-shelf six-switch three-phase drive, mitigating the IGBTs failures by specific inverter control. Indeed, the two topologies exploit the induction motor neutral accessibility for fault-tolerant purposes. The 4-wire topology uses then classical hysteresis controllers to account for the IGBT failures. The 4-leg topology, meanwhile, uses a specific 3D space vector PWM to handle vehicle requirements in terms of size (DC bus capacitors) and cost (IGBTs number). Experiments on an induction motor drive and simulations on an electric vehicle are carried-out using a European urban driving cycle to show that the proposed fault-tolerant control approach is effective and provides a simple configuration with high performance in terms of speed and torque responses. Copyright © 2013 ISA. Published by Elsevier Ltd. All rights reserved.
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Toda, Hiroshi; Itoh, Nobuya
2017-01-01
The novel cryptic pKPAL3 plasmid was isolated from the Gram-positive microorganism Kocuria palustris IPUFS-1 and characterized in detail. pKPAL3 is a circular plasmid that is 4,443 bp in length. Open reading frame (ORF) and homology search analyses indicated that pKPAL3 possesses four ORFs; however, there were no replication protein coding genes predicted in the plasmid. Instead, there were two nucleotide sequence regions that showed significant identities with untranslated regions of K. rhizophila DC2201 (NBRC 103217) genomic sequences, and these sequences were essential for autonomous replication of pKPAL3 in Kocuria cells. Based on these findings, we constructed the novel Escherichia coli - Kocuria shuttle vectors pKITE301 (kanamycin resistant) and pKITE303 (thiostrepton resistant) from pKPAL3. The copy numbers of the constructed shuttle vectors were estimated to be 20 per cell, and they exhibited low segregation stability in Kocuria transformant cells in the absence of antibiotics. Moreover, constructed vectors showed compatibility with the other K. rhizophila shuttle vector pKITE103. We successfully expressed multiple heterologous genes, including the styrene monooxygenase gene from Rhodococcus sp. ST-10 ( rhsmo ) and alcohol dehydrogenase gene from Leifsonia sp. S749 ( lsadh ), in K . rhizophila DC2201 using the pKITE301P and pKITE103P vectors under the control of the glyceraldehyde 3-phosphate dehydrogenase ( gapdh ) promotor. The RhSMO-LSADH co-expressing K. rhizophila was used as a biocatalyst in an organic solvent-water biphasic reaction system to efficiently convert styrene into ( S )-styrene oxide with 99% ee in the presence of 2-propanol as a hydrogen donor. The product concentration of the reaction in the organic solvent reached 235 mM after 30 h under optimum conditions. Thus, we demonstrated that this novel shuttle vector is useful for developing biocatalysts based on organic solvent-tolerant Kocuria cells.
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NASA Astrophysics Data System (ADS)
Matsuda, Y.; Kakutani, K.; Nonomura, T.; Kimbara, J.; Osamura, K.; Kusakar, S.; Toyoda, H.
2015-10-01
An electric field screen can be used to keep mosquitoes out of houses with open windows. In this study, doubly charged dipolar electric field screens (DD-screens) were used to capture mosquitoes entering through a window. The screen had two components: three layers of insulated conductor iron wires (ICWs) in parallel arrays and two electrostatic direct current (DC) voltage generators that supplied negative or positive voltages to the ICWs. Within each layer, the ICWs were parallel at 5-mm intervals, and connected to each other and to a negative or positive voltage generator. The negatively and positively charged ICWs are represented as ICW(-) and ICW(+), respectively. The screen consisted of one ICW(+) layer with an ICW(-) layer on either side. The Asian tiger mosquito (Aedes albopictus) and house mosquito (Culex pipiens) were used as models of vectors carrying viral pathogens. Adult mosquitoes were blown into the space between the ICWs by sending compressed air through the tip of an insect aspirator to determine the voltage range that captured all of the test insects. Wind speed was measured at the surface of the ICW using a sensitive anemometer. The result showed that at ≥ 1.2 kV, the force was strong enough that the ICWs captured all of the mosquitoes, despite a wind speed of 7 m/s. Therefore, the DD-screen could serve as a physical barrier to prevent noxious mosquitoes from entering houses with good air penetration.
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This project investigated an innovative approach for transport of inorganic species under the influence of electric fields. This process, commonly known as electrokinetics uses low-level direct current (dc) electrical potential difference across a soil mass applied through inert...
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Aircraft Electric Secondary Power
NASA Technical Reports Server (NTRS)
1983-01-01
Technologies resulted to aircraft power systems and aircraft in which all secondary power is supplied electrically are discussed. A high-voltage dc power generating system for fighter aircraft, permanent magnet motors and generators for aircraft, lightweight transformers, and the installation of electric generators on turbine engines are among the topics discussed.
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78 FR 23691 - Airworthiness Directives; the Boeing Company
Federal Register 2010, 2011, 2012, 2013, 2014
2013-04-22
... off electrical power to the in-flight entertainment (IFE) systems and other non-essential electrical...., Washington, DC 20590. FOR FURTHER INFORMATION CONTACT: Ray Mei, Aerospace Engineer, Systems and Equipment... circuit breaker, relays, and wiring to allow the flightcrew to turn off electrical power to the IFE...
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Energy Saving in DC Electric Railways by Battery Substation
NASA Astrophysics Data System (ADS)
Sugimoto, Takeshi
New rolling vehicles used in dc electric railways are of the regenerative type. At less busy time a part of regenerative power is not used for powering vehicles, and canceled by changed air brake. Recently, significant attention has been paid to the development of secondary batteries for hybrid and electric motorcars. The use of this battery enables reduction in electric power consumption. Because we can charge excess regenerative power and use for powering vehicles after. Before the fact we compared the actual and simulated effective coefficient of regenerative energy, we confirmed the suitability of the simulation model. In this simulation, we studied the energy-saving effect of the battery substations and determined the battery capacity at which maximum power saving is achieved. We found that the power consumption could be reduced remarkably by using a 15-20kWh battery substation.
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Application of Superconducting Power Cables to DC Electric Railway Systems
NASA Astrophysics Data System (ADS)
Ohsaki, Hiroyuki; Lv, Zhen; Sekino, Masaki; Tomita, Masaru
For novel design and efficient operation of next-generation DC electric railway systems, especially for their substantial energy saving, we have studied the feasibility of applying superconducting power cables to them. In this paper it is assumed that a superconducting power cable is applied to connect substations supplying electric power to trains. An analysis model line was described by an electric circuit, which was analyzed with MATLAB-Simulink. From the calculated voltages and currents of the circuit, the regenerative brake and the energy losses were estimated. In addition, assuming the heat loads of superconducting power cables and the cryogenic efficiency, the energy saving of the total system was evaluated. The results show that the introduction of superconducting power cables could achieve the improved use of regenerative brake, the loss reduction, the decreased number of substations, the reduced maintenance, etc.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Johnson, Karl; Vossos, Vagelis; Kloss, Margarita
2016-09-01
Cost effective zero net energy (ZNE) schemes exist for many types of residential and commercial buildings. Yet, today’s alternating current (AC) based ZNE designs may be as much as 10% to 20% less efficient, more costly, and more complicated than a design based on direct current (DC) technologies. An increasing number of research organizations and manufacturers are just starting the process of developing products and conducting research and development (R&D) efforts. These early R&D efforts indicate that the use of DC technologies may deliver many energy and non-energy benefits relative to AC-based typologies. DC ZNE schemes may provide for anmore » ideal integrating platform for natively DC-based onsite generation, storage, electric vehicle (EV) charging and end-use loads. Emerging empirical data suggest that DC end-use appliances are more efficient, simpler, more durable, and lower cost. DC technologies appear to provide ratepayers a lower cost pathway to achieve resilient ZNE buildings, and simultaneously yield a plethora of benefits. This paper draws from the current research effort entitled "Direct Current as an Integrating and Enabling Platform," co-led by the Lawrence Berkeley National Laboratory (LBNL), the California Institute for Energy and the Environment (CIEE), the Electric Power Research Institute (EPRI) and funded under the California Energy Commission’s Energy Program Investment Charge (CEC EPIC). The first phase of this EPIC research is focused on assembling and summarizing known global performance information on DC and DC-AC hybrid end-use appliances and power systems. This paper summarizes the information and insights gained from this research effort.« less
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Push-pull switching power amplifier
NASA Technical Reports Server (NTRS)
Cuk, Slobodan M. (Inventor)
1980-01-01
A true push-pull switching power amplifier is disclosed utilizing two dc-to-dc converters. Each converter is comprised of two inductances, one inductance in series with a DC source and the other inductor in series with the output load, and an electrical energy transferring device with storage capability, namely storage capacitance, with suitable switching means between the inductances to obtain DC level conversion, where the switching means allows bidirectional current (and power) flow, and the switching means of one dc-to-dc converter is driven by the complement of a square-wave switching signal for the other dc-to-dc converter for true push-pull operation. For reduction of current ripple, the inductances in each of the two converters may be coupled, and with proper design of the coupling, the ripple can be reduced to zero at either the input or the output, but preferably the output.
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Tracking and disturbance rejection of MIMO nonlinear systems with PI controller
NASA Technical Reports Server (NTRS)
Desoer, C. A.; Lin, C. A.
1985-01-01
The tracking and disturbance rejection of a class of MIMO nonlinear systems with a linear proportional plus integral (PI) compensator is studied. Roughly speaking, it is shown that if the given nonlinear plant is exponentially stable and has a strictly increasing dc steady-state I/O map, then a simple PI compensator can be used to yield a stable unity-feedback closed-loop system which asymptotically tracks reference inputs that tend to constant vectors and asymptotically rejects disturbances that tend to constant vectors.
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Tracking and disturbance rejection of MIMO nonlinear systems with PI controller
NASA Technical Reports Server (NTRS)
Desoer, C. A.; Lin, C.-A.
1985-01-01
The tracking and disturbance rejection of a class of MIMO nonlinear systems with linear proportional plus integral (PI) compensator is studied. Roughly speaking, it is shown that if the given nonlinear plant is exponentially stable and has a strictly increasing dc steady-state I/O map, then a simple PI compensator can be used to yield a stable unity-feedback closed-loop system which asymptotically tracks reference inputs that tend to constant vectors and asymptotically rejects disturbances that tend to constant vectors.
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Basic Guidelines to Introduce Electric Circuit Simulation Software in a General Physics Course
ERIC Educational Resources Information Center
Moya, A. A.
2018-01-01
The introduction of electric circuit simulation software for undergraduate students in a general physics course is proposed in order to contribute to the constructive learning of electric circuit theory. This work focuses on the lab exercises based on dc, transient and ac analysis in electric circuits found in introductory physics courses, and…
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The Next Linear Collider Program
/graphics.htm Snowmass 2001 http://snowmass2001.org/ Electrical Systems Modulators http://www -project.slac.stanford.edu/lc/local/electrical/e_home.htm DC Magnet Power http://www-project.slac.stanford.edu/lc/local /electrical/e_home.htm Global Systems http://www-project.slac.stanford.edu/lc/local/electrical/e_home.htm
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Analysis of Ram Acceleration for High Velocity Applications
1991-08-01
South Street Buffalo, NY 14225-0400 Portsmouth, NH 03801-5423 General Electric Company 1 Physics International Company Tactical Systems Department...E. Oran Gaithersburg, MD 20882 Washington, DC 20375-5000 AFOSR/NA 1 Amtec Engineering, Inc. ATTN: Dr. J. Tishkoff P.O. Box 3633 Boiling AFB, DC 20332
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NASA Astrophysics Data System (ADS)
Zhang, Mingyang
2018-06-01
To further study the bidirectional flow problem of V2G (Vehicle to Grid) charge and discharge motor, the mathematical model of AC/DC converter and bi-directional DC/DC converter was established. Then, lithium battery was chosen as the battery of electric vehicle and its mathematical model was established. In order to improve the service life of lithium battery, bidirectional DC/DC converter adopted constant current and constant voltage control strategy. In the initial stage of charging, constant current charging was adopted with current single closed loop control. After reaching a certain value, voltage was switched to constant voltage charging controlled by voltage and current. Subsequently, the V2G system simulation model was built in MATLAB/Simulink. The simulation results verified the correctness of the control strategy and showed that when charging, constant current and constant voltage charging was achieved, the grid side voltage and current were in the same phase, and the power factor was about 1. When discharging, the constant current discharge was applied, and the grid voltage and current phase difference was r. To sum up, the simulation results are correct and helpful.
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Electrified Automotive Powertrain Architecture Using Composite DC–DC Converters
DOE Office of Scientific and Technical Information (OSTI.GOV)
Chen, Hua; Kim, Hyeokjin; Erickson, Robert
In a hybrid or electric vehicle powertrain, a boost dc-dc converter enables reduction of the size of the electric machine and optimization of the battery system. Design of the powertrain boost converter is challenging because the converter must be rated at high peak power, while efficiency at medium-to-light load is critical for the vehicle system performance. By addressing only some of the loss mechanisms, previously proposed efficiency improvement approaches offer limited improvements in size, cost, and efficiency tradeoffs. This article shows how all dominant loss mechanisms in automotive powertrain applications can be mitigated using a new boost composite converter approach.more » In the composite dc-dc architecture, the loss mechanisms associated with indirect power conversion are addressed explicitly, resulting in fundamental efficiency improvements over wide ranges of operating conditions. Several composite converter topologies are presented and compared to state-of-the-art boost converter technologies. It is found that the selected boost composite converter results in a decrease in the total loss by a factor of 2-4 for typical drive cycles. Furthermore, the total system capacitor power rating and energy rating are substantially reduced, which implies potentials for significant reductions in system size and cost.« less
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Electrified Automotive Powertrain Architecture Using Composite DC–DC Converters
Chen, Hua; Kim, Hyeokjin; Erickson, Robert; ...
2017-01-01
In a hybrid or electric vehicle powertrain, a boost dc-dc converter enables reduction of the size of the electric machine and optimization of the battery system. Design of the powertrain boost converter is challenging because the converter must be rated at high peak power, while efficiency at medium-to-light load is critical for the vehicle system performance. By addressing only some of the loss mechanisms, previously proposed efficiency improvement approaches offer limited improvements in size, cost, and efficiency tradeoffs. This article shows how all dominant loss mechanisms in automotive powertrain applications can be mitigated using a new boost composite converter approach.more » In the composite dc-dc architecture, the loss mechanisms associated with indirect power conversion are addressed explicitly, resulting in fundamental efficiency improvements over wide ranges of operating conditions. Several composite converter topologies are presented and compared to state-of-the-art boost converter technologies. It is found that the selected boost composite converter results in a decrease in the total loss by a factor of 2-4 for typical drive cycles. Furthermore, the total system capacitor power rating and energy rating are substantially reduced, which implies potentials for significant reductions in system size and cost.« less
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de Campos, Vânia Emerich Bucco; Teixeira, Cesar Augusto Antunes; da Veiga, Venicio Feo; Júnior, Eduardo Ricci; Holandino, Carla
2010-01-01
Inhibition of tumor growth induced by treatment with direct electric current (DC) has been reported in several models. One of the mechanisms responsible for the antitumoral activity of DC is the generation of oxidative species, known as chloramines. With the aim of increasing chloramine production in the electrolytic medium and optimizing the antitumoral effects of DC, poly(ɛ-caprolactone) (PCL) nanoparticles (NPs) loaded with the amino acid tyrosine were obtained. The physical–chemical characterization showed that the NPs presented size in nanometric range and monomodal distribution. A slightly negative electrokinetic potential was also found in both blank NPs and l-tyrosine-loaded PCL NPs. The yield of the loading process was approximately 50%. Within 3 h of dissolution assay, a burst release of about 80% l-tyrosine was obtained. The in vitro cytotoxicity of DC was significantly increased when associated with l-tyrosine-loaded NPs, using a murine multidrug-resistant melanoma cell line model. This study showed that the use of the combination of nanotechnology and DC has a promising antineoplastic potential and opens a new perspective in cancer therapy. PMID:21187948
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Electrical stimulation of schwann cells promotes sustained increases in neurite outgrowth.
Koppes, Abigail N; Nordberg, Andrea L; Paolillo, Gina M; Goodsell, Nicole M; Darwish, Haley A; Zhang, Linxia; Thompson, Deanna M
2014-02-01
Endogenous electric fields are instructive during embryogenesis by acting to direct cell migration, and postnatally, they can promote axonal growth after injury (McCaig 1991, Al-Majed 2000). However, the mechanisms for these changes are not well understood. Application of an appropriate electrical stimulus may increase the rate and success of nerve repair by directly promoting axonal growth. Previously, DC electrical stimulation at 50 mV/mm (1 mA, 8 h duration) was shown to promote neurite outgrowth and a more pronounced effect was observed if both peripheral glia (Schwann cells) and neurons were co-stimulated. If electrical stimulation is delivered to an injury site, both the neurons and all resident non-neuronal cells [e.g., Schwann cells, endothelial cells, fibroblasts] will be treated and this biophysical stimuli can influence axonal growth directly or indirectly via changes to the resident, non-neuronal cells. In this work, non-neuronal cells were electrically stimulated, and changes in morphology and neuro-supportive cells were evaluated. Schwann cell response (morphology and orientation) was examined after an 8 h stimulation over a range of DC fields (0-200 mV/mm, DC 1 mA), and changes in orientation were observed. Electrically prestimulating Schwann cells (50 mV/mm) promoted 30% more neurite outgrowth relative to co-stimulating both Schwann cells with neurons, suggesting that electrical stimulation modifies Schwann cell phenotype. Conditioned medium from the electrically prestimulated Schwann cells promoted a 20% increase in total neurite outgrowth and was sustained for 72 h poststimulation. An 11-fold increase in nerve growth factor but not brain-derived neurotrophic factor or glial-derived growth factor was found in the electrically prestimulated Schwann cell-conditioned medium. No significant changes in fibroblast or endothelial morphology and neuro-supportive behavior were observed poststimulation. Electrical stimulation is widely used in clinical settings; however, the rational application of this cue may directly impact and enhance neuro-supportive behavior, improving nerve repair.
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NASA Astrophysics Data System (ADS)
Nolan, S.; Jones, C. E.; Munro, R.; Norman, P.; Galloway, S.; Venturumilli, S.; Sheng, J.; Yuan, W.
2017-12-01
Hybrid electric propulsion aircraft are proposed to improve overall aircraft efficiency, enabling future rising demands for air travel to be met. The development of appropriate electrical power systems to provide thrust for the aircraft is a significant challenge due to the much higher required power generation capacity levels and complexity of the aero-electrical power systems (AEPS). The efficiency and weight of the AEPS is critical to ensure that the benefits of hybrid propulsion are not mitigated by the electrical power train. Hence it is proposed that for larger aircraft (~200 passengers) superconducting power systems are used to meet target power densities. Central to the design of the hybrid propulsion AEPS is a robust and reliable electrical protection and fault management system. It is known from previous studies that the choice of protection system may have a significant impact on the overall efficiency of the AEPS. Hence an informed design process which considers the key trades between choice of cable and protection requirements is needed. To date the fault response of a voltage source converter interfaced DC link rail to rail fault in a superconducting power system has only been investigated using simulation models validated by theoretical values from the literature. This paper will present the experimentally obtained fault response for a variety of different types of superconducting tape for a rail to rail DC fault. The paper will then use these as a platform to identify key trades between protection requirements and cable design, providing guidelines to enable future informed decisions to optimise hybrid propulsion electrical power system and protection design.
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Early Oscillation Detection for DC/DC Converter Fault Diagnosis
NASA Technical Reports Server (NTRS)
Wang, Bright L.
2011-01-01
The electrical power system of a spacecraft plays a very critical role for space mission success. Such a modern power system may contain numerous hybrid DC/DC converters both inside the power system electronics (PSE) units and onboard most of the flight electronics modules. One of the faulty conditions for DC/DC converter that poses serious threats to mission safety is the random occurrence of oscillation related to inherent instability characteristics of the DC/DC converters and design deficiency of the power systems. To ensure the highest reliability of the power system, oscillations in any form shall be promptly detected during part level testing, system integration tests, flight health monitoring, and on-board fault diagnosis. The popular gain/phase margin analysis method is capable of predicting stability levels of DC/DC converters, but it is limited only to verification of designs and to part-level testing on some of the models. This method has to inject noise signals into the control loop circuitry as required, thus, interrupts the DC/DC converter's normal operation and increases risks of degrading and damaging the flight unit. A novel technique to detect oscillations at early stage for flight hybrid DC/DC converters was developed.
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Geared Electromechanical Rotary Joint
NASA Technical Reports Server (NTRS)
Vranish, John M.
1994-01-01
Geared rotary joint provides low-noise ac or dc electrical contact between electrical subsystems rotating relative to each other. Designed to overcome some disadvantages of older electromechanical interfaces, especially intermittency of sliding-contact and rolling-contact electromechanical joints. Hollow, springy planetary gears provide continuous, redundant, low-noise electrical contact between inner and outer gears.
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AUTOMOTIVE DIESEL MAINTENANCE 2. UNIT XX, TROUBLESHOOTING ELECTRICAL SYSTEMS.
ERIC Educational Resources Information Center
Minnesota State Dept. of Education, St. Paul. Div. of Vocational and Technical Education.
THIS MODULE OF A 25-MODULE COURSE IS DESIGNED TO ACQUAINT THE TRAINEE WITH TROUBLESHOOTING PROCEDURES FOR DIESEL ENGINE ELECTRICAL SYSTEMS. TOPICS ARE (1) TROUBLESHOOTING ELECTRICAL SYSTEMS (INTRODUCTION), (2) TOOLS AND INSTRUMENTS FOR TROUBLESHOOTING, (3) THE BATTERY, (4) PERIODIC BATTERY SERVICING, (5) THE DC CHARGING SYSTEM, (6) PERIODIC…
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Problem Solving in Electricity.
ERIC Educational Resources Information Center
Caillot, Michel; Chalouhi, Elias
Two studies were conducted to describe how students perform direct current (D-C) circuit problems. It was hypothesized that problem solving in the electricity domain depends largely on good visual processing of the circuit diagram and that this processing depends on the ability to recognize when two or more electrical components are in series or…
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NASA Technical Reports Server (NTRS)
1984-01-01
Kollmorgen Corporation's Mermaid II two person submersible is propeller-driven by a system of five DC brushless motors with new electronic controllers that originated in work performed in a NASA/DOE project managed by Lewis Research Center. A key feature of the system is electric commutation rather than mechanical commutation for converting AC current to DC.
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Discharging a DC bus capacitor of an electrical converter system
Kajouke, Lateef A; Perisic, Milun; Ransom, Ray M
2014-10-14
A system and method of discharging a bus capacitor of a bidirectional matrix converter of a vehicle are presented here. The method begins by electrically shorting the AC interface of the converter after an AC energy source is disconnected from the AC interface. The method continues by arranging a plurality of switching elements of a second energy conversion module into a discharge configuration to establish an electrical current path from a first terminal of an isolation module, through an inductive element, and to a second terminal of the isolation module. The method also modulates a plurality of switching elements of a first energy conversion module, while maintaining the discharge configuration of the second energy conversion module, to at least partially discharge a DC bus capacitor.
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Artificial neural network application for space station power system fault diagnosis
NASA Technical Reports Server (NTRS)
Momoh, James A.; Oliver, Walter E.; Dias, Lakshman G.
1995-01-01
This study presents a methodology for fault diagnosis using a Two-Stage Artificial Neural Network Clustering Algorithm. Previously, SPICE models of a 5-bus DC power distribution system with assumed constant output power during contingencies from the DDCU were used to evaluate the ANN's fault diagnosis capabilities. This on-going study uses EMTP models of the components (distribution lines, SPDU, TPDU, loads) and power sources (DDCU) of Space Station Alpha's electrical Power Distribution System as a basis for the ANN fault diagnostic tool. The results from the two studies are contrasted. In the event of a major fault, ground controllers need the ability to identify the type of fault, isolate the fault to the orbital replaceable unit level and provide the necessary information for the power management expert system to optimally determine a degraded-mode load schedule. To accomplish these goals, the electrical power distribution system's architecture can be subdivided into three major classes: DC-DC converter to loads, DC Switching Unit (DCSU) to Main bus Switching Unit (MBSU), and Power Sources to DCSU. Each class which has its own electrical characteristics and operations, requires a unique fault analysis philosophy. This study identifies these philosophies as Riddles 1, 2 and 3 respectively. The results of the on-going study addresses Riddle-1. It is concluded in this study that the combination of the EMTP models of the DDCU, distribution cables and electrical loads yields a more accurate model of the behavior and in addition yielded more accurate fault diagnosis using ANN versus the results obtained with the SPICE models.
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NASA Astrophysics Data System (ADS)
Al-Taie, A.; Graber, L.; Pamidi, S. V.
2017-12-01
Opportunities for applications of high temperature superconducting (HTS) DC power cables for long distance power transmission in increasing the reliability of the electric power grid and to enable easier integration of distributed renewable sources into the grid are discussed. The gaps in the technology developments both in the superconducting cable designs and cryogenic systems as well as power electronic devices are identified. Various technology components in multi-terminal high voltage DC power transmission networks and the available options are discussed. The potential of ongoing efforts in the development of superconducting DC transmission systems is discussed.
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Vector tomography for reconstructing electric fields with non-zero divergence in bounded domains
DOE Office of Scientific and Technical Information (OSTI.GOV)
Koulouri, Alexandra, E-mail: koulouri@uni-muenster.de; Department of Electrical and Electronic Engineering, Imperial College London, Exhibition Road, London SW7 2BT; Brookes, Mike
In vector tomography (VT), the aim is to reconstruct an unknown multi-dimensional vector field using line integral data. In the case of a 2-dimensional VT, two types of line integral data are usually required. These data correspond to integration of the parallel and perpendicular projection of the vector field along the integration lines and are called the longitudinal and transverse measurements, respectively. In most cases, however, the transverse measurements cannot be physically acquired. Therefore, the VT methods are typically used to reconstruct divergence-free (or source-free) velocity and flow fields that can be reconstructed solely from the longitudinal measurements. In thismore » paper, we show how vector fields with non-zero divergence in a bounded domain can also be reconstructed from the longitudinal measurements without the need of explicitly evaluating the transverse measurements. To the best of our knowledge, VT has not previously been used for this purpose. In particular, we study low-frequency, time-harmonic electric fields generated by dipole sources in convex bounded domains which arise, for example, in electroencephalography (EEG) source imaging. We explain in detail the theoretical background, the derivation of the electric field inverse problem and the numerical approximation of the line integrals. We show that fields with non-zero divergence can be reconstructed from the longitudinal measurements with the help of two sparsity constraints that are constructed from the transverse measurements and the vector Laplace operator. As a comparison to EEG source imaging, we note that VT does not require mathematical modeling of the sources. By numerical simulations, we show that the pattern of the electric field can be correctly estimated using VT and the location of the source activity can be determined accurately from the reconstructed magnitudes of the field. - Highlights: • Vector tomography is used to reconstruct electric fields generated by dipole sources. • Inverse solutions are based on longitudinal and transverse line integral measurements. • Transverse line integral measurements are used as a sparsity constraint. • Numerical procedure to approximate the line integrals is described in detail. • Patterns of the studied electric fields are correctly estimated.« less
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Development of a DC propulsion system for an electric vehicle
NASA Technical Reports Server (NTRS)
Kelledes, W. L.
1984-01-01
The suitability of the Eaton automatically shifted mechanical transaxle concept for use in a near-term dc powered electric vehicle is evaluated. A prototype dc 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 two-axis, three-speed, automatically-shifted mechanical transaxle, 15.2 Kw rated, separately excited traction motor, and a transistorized motor controller with a single chopper providing limited armature current below motor base speed and full range field control above base speed at up to twice rated motor current. The controller utilized a microprocessor to perform motor and vehicle speed monitoring and shift sequencing by means of solenoids applying hydraulic pressure to the transaxle clutches. Bench dynamometer and track testing was performed. Track testing showed best system efficiency for steady-state cruising speeds of 65-80 Km/Hz (40-50 mph). Test results include acceleration, steady speed and SAE J227A/D cycle energy consumption, braking tests and coast down to characterize the vehicle road load.
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NASA Technical Reports Server (NTRS)
Edie, P. C.
1981-01-01
Performance data on the General Electric 5BT 2366C10 series wound dc motor and EV-1 Chopper Controller is supplied for the electric vehicle manufacturer. Data is provided for both straight and chopped dc input to the motor, at 2 motor temperature levels. Testing was done at 6 voltage increments to the motor, and 2 voltage increments to the controller. Data results are presented in both tabular and graphical forms. Tabular information includes motor voltage and current input data, motor speed and torque output data, power data and temperature data. Graphical information includes torque-speed, motor power output-speed, torque-current, and efficiency-speed plots under the various operating conditions. The data resulting from this testing shows the speed-torque plots to have the most variance with operating temperature. The maximum motor efficiency is between 86% and 87%, regardless of temperature or mode of operation. When the chopper is utilized, maximum motor efficiency occurs when the chopper duty cycle approaches 100%.
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Chang, Kuo-Tsai
2007-01-01
This paper investigates electrical transient characteristics of a Rosen-type piezoelectric transformer (PT), including maximum voltages, time constants, energy losses and average powers, and their improvements immediately after turning OFF. A parallel resistor connected to both input terminals of the PT is needed to improve the transient characteristics. An equivalent circuit for the PT is first given. Then, an open-circuit voltage, involving a direct current (DC) component and an alternating current (AC) component, and its related energy losses are derived from the equivalent circuit with initial conditions. Moreover, an AC power control system, including a DC-to-AC resonant inverter, a control switch and electronic instruments, is constructed to determine the electrical characteristics of the OFF transient state. Furthermore, the effects of the parallel resistor on the transient characteristics at different parallel resistances are measured. The advantages of adding the parallel resistor also are discussed. From the measured results, the DC time constant is greatly decreased from 9 to 0.04 ms by a 10 k(omega) parallel resistance under open output.
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Electrical properties of dispersions of graphene in mineral oil
DOE Office of Scientific and Technical Information (OSTI.GOV)
Monteiro, O. R., E-mail: othon.monteiro@bakerhughes.com
2014-02-03
Dispersions of graphene in mineral oil have been prepared and electrical conductivity and permittivity have been measured. The direct current (DC) conductivity of the dispersions depends on the surface characteristics of the graphene platelets and followed a percolation model with a percolation threshold ranging from 0.05 to 0.1 wt. %. The difference in DC conductivities can be attributed to different states of aggregation of the graphene platelets and to the inter-particle electron transfer, which is affected by the surface radicals. The frequency-dependent conductivity (σ(ω)) and permittivity (ε(ω)) were also measured. The conductivity of dispersions with particle contents much greater than themore » percolation threshold remains constant and equal to the DC conductivity at low frequencies ω with and followed a power-law σ(ω)∝ ω{sup s} dependence at very high frequencies with s≈0.9. For dispersions with graphene concentration near the percolation threshold, a third regime was displayed at intermediate frequencies indicative of interfacial polarization consistent with Maxwell-Wagner effect typically observed in mixtures of two (or more) phases with very distinct electrical and dielectric properties.« less
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Power Processing for a Conceptual Project Prometheus Electric Propulsion System
NASA Technical Reports Server (NTRS)
Scina, Joseph E., Jr.; Aulisio, Michael; Gerber, Scott S.; Hewitt, Frank; Miller, Leonard; Elbuluk, Malik; Pinero, Luis R. (Technical Monitor)
2005-01-01
NASA has proposed a bold mission to orbit and explore the moons of Jupiter. This mission, known as the Jupiter Icy Moons Orbiter (JIMO), would significantly increase NASA s capability to explore deep space by making use of high power electric propulsion. One electric propulsion option under study for JIMO is an ion propulsion system. An early version of an ion propulsion system was successfully used on NASA's Deep Space 1 mission. One concept for an ion thruster system capable of meeting the current JIMO mission requirement would have individual thrusters that are 16 to 25 kW each and require voltages as high as 8.0 kV. The purpose of this work is to develop power processing schemes for delivering the high voltage power to the spacecraft ion thrusters based upon a three-phase AC distribution system. In addition, a proposed DC-DC converter topology is presented for an ion thruster ancillary supply based upon a DC distribution system. All specifications discussed in this paper are for design convenience and are speculative in nature.
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NASA Astrophysics Data System (ADS)
El-Bashir, S. M.; Alwadai, N. M.; AlZayed, N.
2018-02-01
Polymer nanocomposite films were prepared by doping fullerene C60 in polymer blend composed of polymethacrylate/polyvinyl acetate blends (PMMA/PVAc) using solution cast technique. The films were characterized by differential scanning calorimeter (DSC), Transmission electron microscope (TEM), DC/AC electrical conductivity and dielectric measurements in the frequency range (100 Hz- 1 MHz). The glass transition temperature, Tg, was increased by increasing the concentration of fullerene C60; this property reflects the increase of thermal stability by increasing the nanofiller content. The DC and AC electrical conductivities were enhanced by increasing C60 concentration due to the electron hopping or tunneling between filled and empty localized states above Tg. The relaxation time was determined from the αβ -relaxations and found to be attenuated by increasing the temperature as a typical behavior of amorphous polymers. The calculated values of thermodynamic parameters revealed the increase of molecular stability by increasing the doping concentration; this feature supports the application of PMMA/PVAc/C60 nanocomposite films in a wide scale of solar energy conversion applications such as luminescent down-shifting (LDS) coatings for photovoltaic cells.
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NASA Astrophysics Data System (ADS)
Simek, Milan; Schmidt, Jiri; Pekarek, Stanislav; Khun, Josef
2006-10-01
We have studied basic optical and electrical characteristics of the DC hollow needle to plate electrical discharge enhanced by the gas flow through the needle. Substantial advantage of this arrangement is that all gas supplied to the discharge passes through the discharge zone and therefore it is affected by plasma chemical processes. Depending on the energy dissipated between electrodes, we previously observed two basic discharge regimes: a) DC corona and b) DC corona superimposed with pulsed filamentary streamers [1]. In this work, we have analyzed radiation induced by filamentary streamers. In addition to nitrogen emissions driven by electron impact processes we have detected emission induced by specific energy transfer processes [2]. We have also determined mean repetition frequency of filamentary streamers (0.1-15 kHz) for the needle-to-plane gap and for the nitrogen flow through the needle ranging between 2-6 mm and 1-10 slm, respectively. [1] M. Simek and S.Pekarek, GEC 2005, Bul. Am. Phys. Soc. 50, 29, (2005) ; [2] M. Simek at al, Pure Appl. Chem. 78, 1213, (2006).
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DC conductivity with external magnetic field in hyperscaling violating geometry
NASA Astrophysics Data System (ADS)
Bhatnagar, Neha; Siwach, Sanjay
2018-02-01
We investigate the holographic DC conductivity of (2+1)-dimensional systems while considering hyperscaling violating geometry in bulk. We consider Einstein-Maxwell-dilaton system with two gauge fields and Liouville-type potential for dilaton. We also consider axionic fields in bulk to introduce momentum relaxation in the system. We apply an external magnetic field to study the response of the system and obtain analytic expressions for DC conductivity, Hall angle and (thermo)electric conductivity.
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Codimension-Two Bifurcation Analysis in DC Microgrids Under Droop Control
NASA Astrophysics Data System (ADS)
Lenz, Eduardo; Pagano, Daniel J.; Tahim, André P. N.
This paper addresses local and global bifurcations that may appear in electrical power systems, such as DC microgrids, which recently has attracted interest from the electrical engineering society. Most sources in these networks are voltage-type and operate in parallel. In such configuration, the basic technique for stabilizing the bus voltage is the so-called droop control. The main contribution of this work is a codimension-two bifurcation analysis of a small DC microgrid considering the droop control gain and the power processed by the load as bifurcation parameters. The codimension-two bifurcation set leads to practical rules for achieving a robust droop control design. Moreover, the bifurcation analysis also offers a better understanding of the dynamics involved in the problem and how to avoid possible instabilities. Simulation results are presented in order to illustrate the bifurcation analysis.
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NASA Astrophysics Data System (ADS)
Lee, J.; Gao, W.; Li, Z.; Hodgson, M.; Metson, J.; Gong, H.; Pal, U.
2005-05-01
Zinc oxide thin films were prepared by dc (direct current) and rf (radio frequency) magnetron sputtering on glass substrates. ZnO films produced by dc sputtering have a high resistance, while the films produced using rf sputtering are significantly more conductive. While the conductive films have a compact nodular surface morphology, the resistive films have a relatively porous surface with columnar structures in cross section. Compared to the dc sputtered films, rf sputtered films have a microstructure with smaller d spacing, lower internal stress, higher band gap energy and higher density. Dependence of conductivity on the deposition technique and the resulting d spacing , stress, density, band gap, film thickness and Al doping are discussed. Correlations between the electrical conductivity, microstructural parameters and optical properties of the films have been made.
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Time-dependent analysis of the mixed-field orientation of molecules without rotational symmetry
NASA Astrophysics Data System (ADS)
Thesing, Linda V.; Küpper, Jochen; González-Férez, Rosario
2017-06-01
We present a theoretical study of the mixed-field orientation of molecules without rotational symmetry. The time-dependent one-dimensional and three-dimensional orientation of a thermal ensemble of 6-chloropyridazine-3-carbonitrile molecules in combined linearly or elliptically polarized laser fields and tilted dc electric fields is computed. The results are in good agreement with recent experimental results of one-dimensional orientation for weak dc electric fields [J. L. Hansen, J. Chem. Phys. 139, 234313 (2013)]. Moreover, they predict that using elliptically polarized laser fields or strong dc fields, three-dimensional orientation is obtained. The field-dressed dynamics of excited rotational states is characterized by highly non-adiabatic effects. We analyze the sources of these non-adiabatic effects and investigate their impact on the mixed-field orientation for different field configurations in mixed-field-orientation experiments.
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New method for solving inductive electric fields in the non-uniformly conducting ionosphere
NASA Astrophysics Data System (ADS)
Vanhamäki, H.; Amm, O.; Viljanen, A.
2006-10-01
We present a new calculation method for solving inductive electric fields in the ionosphere. The time series of the potential part of the ionospheric electric field, together with the Hall and Pedersen conductances serves as the input to this method. The output is the time series of the induced rotational part of the ionospheric electric field. The calculation method works in the time-domain and can be used with non-uniform, time-dependent conductances. In addition, no particular symmetry requirements are imposed on the input potential electric field. The presented method makes use of special non-local vector basis functions called the Cartesian Elementary Current Systems (CECS). This vector basis offers a convenient way of representing curl-free and divergence-free parts of 2-dimensional vector fields and makes it possible to solve the induction problem using simple linear algebra. The new calculation method is validated by comparing it with previously published results for Alfvén wave reflection from a uniformly conducting ionosphere.
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Application of Electric Double-layer Capacitors for Energy Storage on Electric Railway
NASA Astrophysics Data System (ADS)
Hase, Shin-Ichi; Konishi, Takeshi; Okui, Akinobu; Nakamichi, Yoshinobu; Nara, Hidetaka; Uemura, Tadashi
The methods to stabilize power sources, which are the measures against voltage drop, power loading fluctuation, regeneration power lapse and so on, have been important issues in DC feeding circuits. Therefore, an energy storage medium that uses power efficiently and reduces above-mentioned problems is much concerned about. In recent years, development of energy storage medium is remarkable for drive-power supplies of electric vehicles. A number of applications of energy storage, for instance, battery and flywheel, have been investigated so far. A large-scale electric double-layer capacitor which is rapidly charged and discharged and offers long life, maintenance-free, low pollution and high efficiency, has been developed in wide range. We have compared the ability to charge batteries and electric double-layer capacitors. Therefore, we carried out fundamental studies about electric double-layer capacitors and its control. And we produced a prototype of energy storage for the DC electric railway system that consists of electric double-layer capacitors, diode bridge rectifiers, chopper system and PWM converters. From the charge and discharge tests of the prototype, useful information was obtained. This paper describes its characteristics and experimental results of energy storage system.
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Electron microscopy analyses and electrical properties of the layered Bi{sub 2}WO{sub 6} phase
DOE Office of Scientific and Technical Information (OSTI.GOV)
Taoufyq, A.; Laboratoire Matériaux et Environnement LME, Faculté des Sciences, Université Ibn Zohr, BP 8106, Cité Dakhla, Agadir, Maroc; Département d‘Études des Réacteurs, Laboratoire Dosimétrie Capteurs Instrumentation, CEA Cadarache
2013-07-15
The bismuth tungstate Bi{sub 2}WO{sub 6} was synthesized using a classical coprecipitation method followed by a calcination process at different temperatures. The samples were characterized by X-ray diffraction, simultaneous thermogravimetry and differential thermal analysis (TGA/DTA), scanning and transmission electron microscopy (SEM, TEM) analyses. The Rietveld analysis and electron diffraction clearly confirmed the Pca2{sub 1} non centrosymmetric space group previously proposed for this phase. The layers Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} have been directly evidenced from the HRTEM images. The electrical properties of Bi{sub 2}WO{sub 6} compacted pellets systems were determined from electrical impedance spectrometry (EIS) and directmore » current (DC) analyses, under air and argon, between 350 and 700 °C. The direct current analyses showed that the conduction observed from EIS analyses was mainly ionic in this temperature range, with a small electronic contribution. Electrical change above the transition temperature of 660 °C is observed under air and argon atmospheres. The strong conductivity increase observed under argon is interpreted in terms of formation of additional oxygen vacancies coupled with electron conduction. - Graphical abstract: High resolution transmission electron microscopy: inverse fast Fourier transform giving the layered structure of the Bi{sub 2}WO{sub 6} phase, with a representation of the cell dimensions (b and c vectors). The Bi{sub 2}O{sub 2}{sup 2+} and WO{sub 4}{sup 2−} sandwiches are visible in the IFFT image. - Highlights: • Using transmission electron microscopy, we visualize the layered structure of Bi{sub 2}WO{sub 6}. • Electrical analyses under argon gas show some increase in conductivity. • The phase transition at 660 °C is evidenced from electrical modification.« less
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NASA Astrophysics Data System (ADS)
Rudin, Sergey; Rupper, Greg; Kachorovski, Valentin; Shur, Michael S.
2017-05-01
The electromagnetic wave impinging on the spatially modulated two-dimensional electron liquid (2DEL) induces a direct current (DC) when the wave amplitude modulated with the same wave vector as the 2DEL but is shifted in phase (the ratchet effect). The recent theory of this phenomenon predicted a dramatic enhancement at the plasmonic resonances and a non-trivial polarization dependence [1]. We will present the results of the numerical simulations using a hydrodynamic model exploring the helicity dependence of the DC current for silicon, InGaAs, and GaN metamaterial structures at cryogenic and room temperatures. In particular we will report on the effect of the DEL viscosity and explore the nonlinear effects at large amplitudes of the helical electromagnetic radiation impinging on the ratchet structures. We will then discuss the applications of the ratchet effect for terahertz metamaterials in order to realize ultra-sensitive terahertz (THz) radiation detectors, modulators, phase shifters, and delay lines with cross sections matching the terahertz wavelength and capable of determining the electromagnetic wave polarization and helicity. To this end, we propose and analyze the four contact ratchet devices capable of registering the two perpendicular components of the electric currents induced by the elliptically or circularly polarized radiation and analyze the load impedance effects in the structures optimized for the ratchet metamaterial THz components. The analysis is based on the hydrodynamic model suitable for the multi-gated semiconductor structures, coupled self-consistently with Poisson's equation for the electric potential. The model accounts for the effects of pressure gradients and 2DEL viscosity. Our numerical solutions are applicable to the wide ranges of electron mobility and terahertz power. [1] I. V. Rozhansky, V. Yu. Kachorovskii, and M. S. Shur, Helicity-Driven Ratchet Effect Enhanced by Plasmons, Phys. Rev. Lett. 114, 246601, 15 June 2015
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Reversible vector ratchets for skyrmion systems
NASA Astrophysics Data System (ADS)
Ma, X.; Reichhardt, C. J. Olson; Reichhardt, C.
2017-03-01
We show that ac driven skyrmions interacting with an asymmetric substrate provide a realization of a class of ratchet system which we call a vector ratchet that arises due to the effect of the Magnus term on the skyrmion dynamics. In a vector ratchet, the dc motion induced by the ac drive can be described as a vector that can be rotated clockwise or counterclockwise relative to the substrate asymmetry direction. Up to a full 360∘ rotation is possible for varied ac amplitudes or skyrmion densities. In contrast to overdamped systems, in which ratchet motion is always parallel to the substrate asymmetry direction, vector ratchets allow the ratchet motion to be in any direction relative to the substrate asymmetry. It is also possible to obtain a reversal in the direction of rotation of the vector ratchet, permitting the creation of a reversible vector ratchet. We examine vector ratchets for ac drives applied parallel or perpendicular to the substrate asymmetry direction, and show that reverse ratchet motion can be produced by collective effects. No reversals occur for an isolated skyrmion on an asymmetric substrate. Since a vector ratchet can produce motion in any direction, it could represent a method for controlling skyrmion motion for spintronic applications.
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NPDES Permit for Potomac Electric Power Company (PEPCO) Benning Generating Station
Under National Pollutant Discharge Elimination System permit number DC0000094, the Potomac Electric Power Company (PEPCO) Benning Generating Station is authorized to discharge from from a facility to receiving waters named Anacostia River.
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76 FR 20968 - Application To Export Electric Energy; DC Energy Texas, LLC
Federal Register 2010, 2011, 2012, 2013, 2014
2011-04-14
..., controls or operates any electric transmission facilities, nor do they hold a franchise service area for... supply system. Copies of this application will be made available, upon request, for public inspection and...
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Trap Modulated Charge Carrier Transport in Polyethylene/Graphene Nanocomposites.
Li, Zhonglei; Du, Boxue; Han, Chenlei; Xu, Hang
2017-06-21
The role of trap characteristics in modulating charge transport properties is attracting much attentions in electrical and electronic engineering, which has an important effect on the electrical properties of dielectrics. This paper focuses on the electrical properties of Low-density Polyethylene (LDPE)/graphene nanocomposites (NCs), as well as the corresponding trap level characteristics. The dc conductivity, breakdown strength and space charge behaviors of NCs with the filler content of 0 wt%, 0.005 wt%, 0.01 wt%, 0.1 wt% and 0.5 wt% are studied, and their trap level distributions are characterized by isothermal discharge current (IDC) tests. The experimental results show that the 0.005 wt% LDPE/graphene NCs have a lower dc conductivity, a higher breakdown strength and a much smaller amount of space charge accumulation than the neat LDPE. It is indicated that the graphene addition with a filler content of 0.005 wt% introduces large quantities of deep carrier traps that reduce charge carrier mobility and result in the homocharge accumulation near the electrodes. The deep trap modulated charge carrier transport attributes to reduce the dc conductivity, suppress the injection of space charges into polymer bulks and enhance the breakdown strength, which is of great significance in improving electrical properties of polymer dielectrics.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Wang, Tengxing; Peng, Yujia; Jiang, Wei
Tunable radio frequency (RF) components are pivotal elements in frequency-agile and multifunctional systems. However, there is a technical barrier to achieve miniaturized fully electrically tunable RF components. This paper provides and demonstrates the efficacy of a first unique design methodology in developing fully electrically tunable RF components by integrating ferromagnetic (e.g., Permalloy) and ferroelectric (e.g., Lead Zirconate Titanate: PZT) thin films patterns. Permalloy thin film has been patterned in nanometer scale to improve its ferromagnetic resonance frequency (FMR) for RF applications. Tunable inductors are developed with the utilization of different thickness of Permalloy thin film, which show over 50% incrementmore » in inductance and over 4% in tunability with DC current. More tunability can be achieved with multiple layers of Permalloy thin film and optimized thickness. A fully electrically tunable slow wave RF transmission line with simultaneously variable inductance and capacitance density has been implemented and thoroughly investigated for the first time. Measured results show that a fixed phase shift of 90° can be achieved from 1.5 GHz to 1.85 GHz continuously by applying external DC current from 0 to 200 mA and external DC voltage from 0 to 15 Volts, respectively.« less
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Pan, Linjie; Cirillo, John; Borgens, Richard Ben
2012-08-01
The remarkable polarity-dependent growth and anatomical organization of neurons in vitro produced by imposed direct current (DC) voltage gradients (electrical fields; Ef) can be mimicked by another type of electrical cue. This is a properly structured asymmetrical alternating current (AC) electrical field (A-ACEf). Here we provide details on the construction of an AC signal generator in which all components of an AC waveform can be individually controlled. We show that 1) conventional symmetrical AC voltage gradients will not induce growth, guidance, or architectural changes in sympathetic neurons. We also provide the first qualitative and quantitative data showing that an asymmetric AC application can indeed mimic the DC response in chick sympathetic neurons and their growing neurites. This shift in orientation and neuronal anatomy requires dieback of some neurites and the extension of others to produce a preferred orientation perpendicular to the gradient of voltage. Our new results may lead to a noninvasive means to modify nerve growth and organization by magnetic inductive coupling at distance. These data also indicate the possibility of a means to mimic DC-dependent release of drugs or other biologically active molecules from electrically sensitive that can be loaded with these chemical cargos. Copyright © 2012 Wiley Periodicals, Inc.
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Wang, Tengxing; Peng, Yujia; Jiang, Wei; ...
2016-10-31
Tunable radio frequency (RF) components are pivotal elements in frequency-agile and multifunctional systems. However, there is a technical barrier to achieve miniaturized fully electrically tunable RF components. This paper provides and demonstrates the efficacy of a first unique design methodology in developing fully electrically tunable RF components by integrating ferromagnetic (e.g., Permalloy) and ferroelectric (e.g., Lead Zirconate Titanate: PZT) thin films patterns. Permalloy thin film has been patterned in nanometer scale to improve its ferromagnetic resonance frequency (FMR) for RF applications. Tunable inductors are developed with the utilization of different thickness of Permalloy thin film, which show over 50% incrementmore » in inductance and over 4% in tunability with DC current. More tunability can be achieved with multiple layers of Permalloy thin film and optimized thickness. A fully electrically tunable slow wave RF transmission line with simultaneously variable inductance and capacitance density has been implemented and thoroughly investigated for the first time. Measured results show that a fixed phase shift of 90° can be achieved from 1.5 GHz to 1.85 GHz continuously by applying external DC current from 0 to 200 mA and external DC voltage from 0 to 15 Volts, respectively.« less
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NASA Astrophysics Data System (ADS)
1980-06-01
Fabrication of the inductor motor, the flywheel, the power conditioner, and the system control is described. Test results of the system operating over the SAE j227a Schedule D driving cycle are given and are compared to the calculated value. The flywheel energy storage system consists of a solid rotor, synchronous, inductor-type, flywheel drive machine electrically coupled to a dc battery electric propulsion system through a load-commutated inverter. The motor/alernator unit is coupled mechanically to a small steel flywheel which provides a portion of the vehicle's accelerating energy and regenerates the vehicle's braking energy. Laboratory simulation of the electric vehicle propulsion system included a 108 volt, lead-acid battery bank and a separately excited dc propulsion motor coupled to a flywheel and generator which simulate the vehicle's inertia and losses.
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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.
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Electrical Stimulation Technologies for Wound Healing
Kloth, Luther C.
2014-01-01
Objective: To discuss the physiological bases for using exogenously applied electric field (EF) energy to enhance wound healing with conductive electrical stimulation (ES) devices. Approach: To describe the types of electrical currents that have been reported to enhance chronic wound-healing rate and closure. Results: Commercial ES devices that generate direct current (DC), and mono and biphasic pulsed current waveforms represent the principal ES technologies which are reported to enhance wound healing. Innovation: Wafer-thin, disposable ES technologies (wound dressings) that utilize mini or micro-batteries to deliver low-level DC for wound healing and antibacterial wound-treatment purposes are commercially available. Microfluidic wound-healing chips are currently being used with greater accuracy to investigate the EF effects on cellular electrotaxis. Conclusion: Numerous clinical trials described in subsequent sections of this issue have demonstrated that ES used adjunctively with standard wound care (SWC), enhances wound healing rate faster than SWC alone. PMID:24761348
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Method for multi-axis, non-contact mixing of magnetic particle suspensions
DOE Office of Scientific and Technical Information (OSTI.GOV)
Martin, James E.; Solis, Kyle J.
Continuous, three-dimensional control of the vorticity vector is possible by progressively transitioning the field symmetry by applying or removing a dc bias along one of the principal axes of mutually orthogonal alternating fields. By exploiting this transition, the vorticity vector can be oriented in a wide range of directions that comprise all three spatial dimensions. Detuning one or more field components to create phase modulation causes the vorticity vector to trace out complex orbits of a wide variety, creating very robust multiaxial stirring. This multiaxial, non-contact stirring is particularly attractive for applications where the fluid volume has complex boundaries, ormore » is congested.« less
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Video-rate terahertz electric-field vector imaging
DOE Office of Scientific and Technical Information (OSTI.GOV)
Takai, Mayuko; Takeda, Masatoshi; Sasaki, Manabu
We present an experimental setup to dramatically reduce a measurement time for obtaining spatial distributions of terahertz electric-field (E-field) vectors. The method utilizes the electro-optic sampling, and we use a charge-coupled device to detect a spatial distribution of the probe beam polarization rotation by the E-field-induced Pockels effect in a 〈110〉-oriented ZnTe crystal. A quick rotation of the ZnTe crystal allows analyzing the terahertz E-field direction at each image position, and the terahertz E-field vector mapping at a fixed position of an optical delay line is achieved within 21 ms. Video-rate mapping of terahertz E-field vectors is likely to bemore » useful for achieving real-time sensing of terahertz vector beams, vector vortices, and surface topography. The method is also useful for a fast polarization analysis of terahertz beams.« less
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Dipole interaction of the Quincke rotating particles.
Dolinsky, Yu; Elperin, T
2012-02-01
We study the behavior of particles having a finite electric permittivity and conductivity in a weakly conducting fluid under the action of the external electric field. We consider the case when the strength of the external electric field is above the threshold, and particles rotate due to the Quincke effect. We determine the magnitude of the dipole interaction of the Quincke rotating particles and the shift of frequency of the Quincke rotation caused by the dipole interaction between the particles. It is demonstrated that depending on the mutual orientation of the vectors of angular velocities of particles, vector-directed along the straight line between the centers of the particles and the external electric field strength vector, particles can attract or repel each other. In contrast to the case of nonrotating particles when the magnitude of the dipole interaction increases with the increase of the strength of the external electric field, the magnitude of the dipole interaction of the Quincke rotating particles either does not change or decreases with the increase of the strength of the external electric field depending on the strength of the external electric field and electrodynamic parameters of the particles.
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Dipole interaction of the Quincke rotating particles
NASA Astrophysics Data System (ADS)
Dolinsky, Yu.; Elperin, T.
2012-02-01
We study the behavior of particles having a finite electric permittivity and conductivity in a weakly conducting fluid under the action of the external electric field. We consider the case when the strength of the external electric field is above the threshold, and particles rotate due to the Quincke effect. We determine the magnitude of the dipole interaction of the Quincke rotating particles and the shift of frequency of the Quincke rotation caused by the dipole interaction between the particles. It is demonstrated that depending on the mutual orientation of the vectors of angular velocities of particles, vector-directed along the straight line between the centers of the particles and the external electric field strength vector, particles can attract or repel each other. In contrast to the case of nonrotating particles when the magnitude of the dipole interaction increases with the increase of the strength of the external electric field, the magnitude of the dipole interaction of the Quincke rotating particles either does not change or decreases with the increase of the strength of the external electric field depending on the strength of the external electric field and electrodynamic parameters of the particles.
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Software and hardware complex for research and management of the separation process
NASA Astrophysics Data System (ADS)
Borisov, A. P.
2018-01-01
The article is devoted to the development of a program for studying the operation of an asynchronous electric drive using vector-algorithmic switching of windings, as well as the development of a hardware-software complex for controlling parameters and controlling the speed of rotation of an asynchronous electric drive for investigating the operation of a cyclone. To study the operation of an asynchronous electric drive, a method was used in which the average value of flux linkage is found and a method for vector-algorithmic calculation of the power and electromagnetic moment of an asynchronous electric drive feeding from a single-phase network is developed, with vector-algorithmic commutation, and software for calculating parameters. The software part of the complex allows to regulate the speed of rotation of the motor by vector-algorithmic switching of transistors or, using pulse-width modulation (PWM), set any engine speed. Also sensors are connected to the hardware-software complex at the inlet and outlet of the cyclone. The developed cyclone with an inserted complex allows to receive high efficiency of product separation at various entrance speeds. At an inlet air speed of 18 m / s, the cyclone’s maximum efficiency is achieved. For this, it is necessary to provide the rotational speed of an asynchronous electric drive with a frequency of 45 Hz.
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NASA Technical Reports Server (NTRS)
Kimnach, Greg L.; Lebron, Ramon C.
1999-01-01
The Fluid Combustion Facility (FCF) Project and the Power Technology Division at the NASA Glenn Research Center (GRC) at Lewis Field in Cleveland, OH along with the Sundstrand Corporation in Rockford, IL are jointly developing an Electrical Power Converter Unit (EPCU) for the Fluid Combustion Facility to be flown on the International Space Station (ISS). The FCF facility experiment contains three racks: A core rack, a combustion rack, and a fluids rack. The EPCU will be used as the power interface to the ISS 120V(sub dc) power distribution system by each FCF experiment rack which requires 28V(sub dc). The EPCU is a modular design which contains three 120V(sub dc)-to-28V(sub dc) full-bridge, power converters rated at 1 kW(sub e) each bus transferring input relays and solid-state, current-limiting input switches, 48 current-limiting, solid-state, output switches; and control and telemetry hardware. The EPCU has all controls required to autonomously share load demand between the power feeds and--if absolutely necessary--shed loads. The EPCU, which maximizes the usage of allocated ISS power and minimizes loss of power to loads, can be paralleled with other EPCUs. This paper overviews the electrical design and operating characteristics of the EPCU and presents test data from the breadboard design.
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A sensor for vector electric field measurements through a nonlinear anisotropic optical crystal
NASA Astrophysics Data System (ADS)
Barbieri, Luca; Gondola, Marco; Potenza, Marco; Villa, Andrea; Malgesini, Roberto
2017-11-01
Electrical applications require the development of electric field sensors that can reproduce vector electric field waveforms with a very large spectral width ranging from 50 Hz to at least 70 MHz. This makes it possible to measure both the normal operation modes of electrical components and abnormal behaviors such as the corona emission and partial discharges. In this work, we aim to develop a fully dielectric sensor capable of measuring two components of the electric field using a wide class of optical crystals including anisotropic ones, whereas most of the efforts in this field have been devoted to isotropic crystals. We report the results of the measurements performed at 50 Hz and with a lightning impulse, to validate the sensor.
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Giant Permittivity in Epitaxial Ferroelectric Heterostructures
NASA Astrophysics Data System (ADS)
Erbil, A.; Kim, Y.; Gerhardt, R. A.
1996-08-01
A giant permittivity associated with the motion of domain walls is reported in epitaxial hetero- structures having alternating layers of ferroelectric and nonferroelectric oxides. At low frequencies, permittivities as high as 420 000 are found. Real and imaginary parts of the dielectric constant show large dispersion at high frequencies. In dc measurements, a nonlinear resistance is observed with a well-defined threshold field correlated with the dc bias-field dependence of ac permittivities. We interpret the observations as a result of the motion of a pinned domain wall lattice at low electric fields and sliding-mode motion at high electric fields.
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Electromagnetic Flow Meter Having a Driver Circuit Including a Current Transducer
NASA Technical Reports Server (NTRS)
Patel, Sandeep K. (Inventor); Karon, David M. (Inventor); Cushing, Vincent (Inventor)
2014-01-01
An electromagnetic flow meter (EMFM) accurately measures both the complete flow rate and the dynamically fluctuating flow rate of a fluid by applying a unipolar DC voltage to excitation coils for a predetermined period of time, measuring the electric potential at a pair of electrodes, determining a complete flow rate and independently measuring the dynamic flow rate during the "on" cycle of the DC excitation, and correcting the measurements for errors resulting from galvanic drift and other effects on the electric potential. The EMFM can also correct for effects from the excitation circuit induced during operation of the EMFM.
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Electromagnetic induction pump for pumping liquid metals and other conductive liquids
Smither, R.K.
1993-05-11
An electromagnetic induction pump is described in which an electrically conductive liquid is made to flow by means of a force created by interaction of a permanent magnetic field and a DC current. The pump achieves high efficiency through combination of: powerful permanent magnet materials which provide a high strength field that is uniform and constant; steel tubing formed into a coil which is constructed to carry conducting liquids with minimal electrical resistance and heat; and application of a voltage to induce a DC current which continuously produces a force in the direction of the desired flow.
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Electromagnetic induction pump for pumping liquid metals and other conductive liquids
Smither, Robert K.
1993-01-01
An electromagnetic induction pump in which an electrically conductive liquid is made to flow by means of a force created by interaction of a permanent magnetic field and a DC current. The pump achieves high efficiency through combination of: powerful permanent magnet materials which provide a high strength field that is uniform and constant; steel tubing formed into a coil which is constructed to carry conducting liquids with minimal electrical resistance and heat; and application of a voltage to induce a DC current which continuously produces a force in the direction of the desired flow.
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ELECTRICAL CIRCUITS USING COLD-CATHODE TRIODE VALVES
Goulding, F.S.
1957-11-26
An electrical circuit which may be utilized as a pulse generator or voltage stabilizer is presented. The circuit employs a cold-cathode triode valve arranged to oscillate between its on and off stages by the use of selected resistance-capacitance time constant components in the plate and trigger grid circuits. The magnitude of the d-c voltage applied to the trigger grid circuit effectively controls the repetition rate of the output pulses. In the voltage stabilizer arrangement the d-c control voltage is a portion of the supply voltage and the rectified output voltage is substantially constant.
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Methods to characterize charging effects
NASA Astrophysics Data System (ADS)
Slots, H.
1984-08-01
Methods to characterize charging in insulating material under high voltage dc stress, leading to electrical breakdown, are reviewed. The behavior of the charges can be studied by ac loss angle measurements after application or removal of dc bias. Measurements were performed on oil-paper and oil-Mylar systems. The poor reproducibility of the measurements makes it impossible to draw more than qualitative conclusions about the charging effects. With an ultrasound pressure wave the electric field distribution in a material can be determined. An alternative derivation for the transient response of a system which elucidates the influence of several parameters in a simple way is given.
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NASA Technical Reports Server (NTRS)
Neudeck, Philip G.; Chen, Liangyu; Spry, David J.; Beheim, Glenn M.; Chang, Carl W.
2014-01-01
This work reports DC electrical characterization of a 76 mm diameter 4H-SiC JFET test wafer fabricated as part of NASA's on-going efforts to realize medium-scale ICs with prolonged and stable circuit operation at temperatures as high as 500 degC. In particular, these measurements provide quantitative parameter ranges for use in JFET IC design and simulation. Larger than expected parameter variations were observed both as a function of position across the wafer as well as a function of ambient testing temperature from 23 degC to 500 degC.
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NASA Technical Reports Server (NTRS)
Wang, R.; Demerdash, N. A.
1991-01-01
A method of combined use of magnetic vector potential based finite-element (FE) formulations and magnetic scalar potential (MSP) based formulations for computation of three-dimensional magnetostatic fields is introduced. In this method, the curl-component of the magnetic field intensity is computed by a reduced magnetic vector potential. This field intensity forms the basic of a forcing function for a global magnetic scalar potential solution over the entire volume of the region. This method allows one to include iron portions sandwiched in between conductors within partitioned current-carrying subregions. The method is most suited for large-scale global-type 3-D magnetostatic field computations in electrical devices, and in particular rotating electric machinery.
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Huygens' optical vector wave field synthesis via in-plane electric dipole metasurface.
Park, Hyeonsoo; Yun, Hansik; Choi, Chulsoo; Hong, Jongwoo; Kim, Hwi; Lee, Byoungho
2018-04-16
We investigate Huygens' optical vector wave field synthesis scheme for electric dipole metasurfaces with the capability of modulating in-plane polarization and complex amplitude and discuss the practical issues involved in realizing multi-modulation metasurfaces. The proposed Huygens' vector wave field synthesis scheme identifies the vector Airy disk as a synthetic unit element and creates a designed vector optical field by integrating polarization-controlled and complex-modulated Airy disks. The metasurface structure for the proposed vector field synthesis is analyzed in terms of the signal-to-noise ratio of the synthesized field distribution. The design of practical metasurface structures with true vector modulation capability is possible through the analysis of the light field modulation characteristics of various complex modulated geometric phase metasurfaces. It is shown that the regularization of meta-atoms is a key factor that needs to be considered in field synthesis, given that it is essential for a wide range of optical field synthetic applications, including holographic displays, microscopy, and optical lithography.
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Xiao, Wendan; Li, Dan; Ye, Xuezhu; Xu, Haizhou; Yao, Guihua; Wang, Jingwen; Zhang, Qi; Hu, Jing; Gao, Na
2017-02-01
The combined use of organic amendment-assisted phytoextraction and electrokinetic remediation to decontaminate Cd-polluted soil was demonstrated in a laboratory-scale experiment. The plant species selected was the hyperaccumulator Sedum alfredii. Prior to the pot experiment, the loamy soil was treated with 15 g kg -1 of pig manure compost, 10 g kg -1 of humic acid, or 5 mmol kg -1 of EDTA, and untreated soil without application of any amendment was the control. Two conditions were applied to each treatment: no voltage (without an electrical field) and a direct current (DC) electrical field (1 V cm -1 with switching polarity every day). Results indicated that Cd concentrations in S. alfredii were significantly (p < 0.05) increased by application of the electrical field and soil amendments (pig manure compost, humic acid, and EDTA). By switching the polarity of the DC electrical field, significant pH variation from anode to cathode can be avoided, and no significant impact was observed on shoot biomass production. Electrical field application increased DTPA-extractable Cd in soils and the Cd accumulation in shoots by 6.06-15.64 and 24.53-52.31%, respectively. The addition of pig manure compost and humic acid enhanced shoot Cd accumulation by 1.54- to 1.92- and 1.38- to 1.64-fold because of their simultaneous enhancement of Cd concentration in shoots and biomass production. However, no enhancement of Cd accumulation was found in the EDTA treatment, which can be ascribed to the inhibition of plant growth caused by EDTA. In conclusion, pig manure compost or humic acid addition in combination with the application of a switched-polarity DC electrical field could significantly enhance Cd phytoextraction by hyperaccumulator S. alfredii.
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Federal Register 2010, 2011, 2012, 2013, 2014
2012-11-16
... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. RM10-12-000] Electricity Market Transparency Provisions of Section 220 of the Federal Power Act; Notice of Technical Conference...., Washington, DC 20426. \\1\\ Electricity Market Transparency Provisions of Section 220 of the Federal Power Act...
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ERIC Educational Resources Information Center
Burkett, Susan L.; Kotru, Sushma; Lusth, John C.; McCallum, Debra; Dunlap, Sarah
2014-01-01
Dunlap, The University of Alabama, USA ABSTRACT In the electrical and computer engineering (ECE) curriculum at The University of Alabama, freshmen are introduced to fundamental electrical concepts and units, DC circuit analysis techniques, operational amplifiers, circuit simulation, design, and professional ethics. The two credit course has both…
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Introduction to the Control of Electric Motors.
ERIC Educational Resources Information Center
Spencer, Frederick
The fundamentals of electric circuits and electric machines are presented in the text, with an emphasis on the practical operation rather than on mathematical analyses of theories involved. The material contained in the text includes the fundamentals of both D.C. and A.C. circuits together with the principles of magnetism and electro-magnetic…
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46 CFR 129.120 - Alternative standards.
Code of Federal Regulations, 2010 CFR
2010-10-01
... or less may meet the following requirements of the American Yacht and Boat Council Projects, where applicable, instead of § 129.340 of this part: (1) E-1, Bonding of Direct Current Systems. (2) E-8, AC Electrical Systems on Boats. (3) E-9, DC Electrical Systems on Boats. (b) An OSV with an electrical...
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Calculating Electrical Requirements for Direct Current Electric Actuators
2017-11-29
These requirements lead to the determination of multiple design decisions such as: operating voltage, regenerative energy capture/dissipation, and...15. SUBJECT TERMS Electro-mechanical actuation Regenerative energy Electrical power Servo control Direct current (DC...Method 6 Power Supply Requirements 7 Approaches to Handling Regenerative Energy 8 Conductor Selection 10 Results and Discussions 10 Example
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DC-magnetic field vector measurement
NASA Technical Reports Server (NTRS)
Schmidt, R.
1981-01-01
A magnetometer experiment was designed to determine the local magnetic field by measuring the total of the Earth's magnetic field and that of an unknown spacecraft. The measured field vector components are available to all onboard experiments via the Spacelab command and data management system. The experiment consists of two parts, an electronic box and the magnetic field sensor. The sensor includes three independent measuring flux-gate magnetometers, each measuring one component. The physical background is the nonlinearity of the B-H curve of a ferrite material. Two coils wound around a ferrite rod are necessary. One of them, a tank coil, pumps the ferrite rod at approximately 20 kilohertz. As a consequence of the nonlinearity, many harmonics can be produced. The second coil (i.e., the detection coil) resonates to the first harmonic. If an unknown dc or low-frequency magnetic field exists, the amplitude of the first harmonic is a measure for the unknown magnetic field. The voltages detected by the sensors are to be digitized and transferred to the command and data management system.
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van Herpen, Gerard
2014-01-01
Einthoven not only designed a high quality instrument, the string galvanometer, for recording the ECG, he also shaped the conceptual framework to understand it. He reduced the body to an equilateral triangle and the cardiac electric activity to a dipole, represented by an arrow (i.e. a vector) in the triangle's center. Up to the present day the interpretation of the ECG is based on the model of a dipole vector being projected on the various leads. The model is practical but intuitive, not physically founded. Burger analysed the relation between heart vector and leads according to the principles of physics. It then follows that an ECG lead must be treated as a vector (lead vector) and that the lead voltage is not simply proportional to the projection of the vector on the lead, but must be multiplied by the value (length) of the lead vector, the lead strength. Anatomical lead axis and electrical lead axis are different entities and the anatomical body space must be distinguished from electrical space. Appreciation of these underlying physical principles should contribute to a better understanding of the ECG. The development of these principles by Burger is described, together with some personal notes and a sketch of the personality of this pioneer of medical physics. Copyright © 2014. Published by Elsevier Inc.
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1992-08-27
Materials Science Center of Excellence REPORT NUMBER Howard University School of Engineering MSRCE ONR 1 2300 6th St., N.W. Washington, D.C. 20059 9...Research Center of Excellence, Department of Electrical Engineering, School of Engineering, Howard University , Washington, D.C., USA Abstract We report
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27. View looking to port from ship's centerline toward main ...
27. View looking to port from ship's centerline toward main electrical control panel, behind which is DC-AC motor-generator set. DC dynamo appears at lower right of image, waste water overflow pipe from hot well appears in upper right of image. - Ferry TICONDEROGA, Route 7, Shelburne, Chittenden County, VT
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Xue, Yaosuo
The matrix converter solid state transformer (MC-SST), formed from the back-to-back connection of two three-to-single-phase matrix converters, is studied for use in the interconnection of two ac grids. The matrix converter topology provides a light weight and low volume single-stage bidirectional ac-ac power conversion without the need for a dc link. Thus, the lifetime limitations of dc-bus storage capacitors are avoided. However, space vector modulation of this type of MC-SST requires to compute vectors for each of the two MCs, which must be carefully coordinated to avoid commutation failure. An additional controller is also required to control power exchange betweenmore » the two ac grids. In this paper, model predictive control (MPC) is proposed for an MC-SST connecting two different ac power grids. The proposed MPC predicts the circuit variables based on the discrete model of MC-SST system and the cost function is formulated so that the optimal switch vector for the next sample period is selected, thereby generating the required grid currents for the SST. Simulation and experimental studies are carried out to demonstrate the effectiveness and simplicity of the proposed MPC for such MC-SST-based grid interfacing systems.« less
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New perspectives on the dynamics of AC and DC plasma arcs exposed to cross-fields
NASA Astrophysics Data System (ADS)
Abdo, Youssef; Rohani, Vandad; Cauneau, François; Fulcheri, Laurent
2017-02-01
Interactions between an arc and external fields are crucially important for the design and the optimization of modern plasma torches. Multiple studies have been conducted to help better understand the behavior of DC and AC current arcs exposed to external and ‘self-induced’ magnetic fields, but the theoretical foundations remain very poorly explored. An analytical investigation has therefore been carried out in order to study the general behavior of DC and AC arcs under the effect of random cross-fields. A simple differential equation describing the general behavior of a planar DC or AC arc has been obtained. Several dimensionless numbers that depend primarily on arc and field parameters and the main arc characteristics (temperature, electric field strength) have also been determined. Their magnitude indicates the general tendency pattern of the arc evolution. The analytical results for many case studies have been validated using an MHD numerical model. The main purpose of this investigation was deriving a practical analytical model for the electric arc, rendering possible its stabilization and control, and the enhancement of the plasma torch power.
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Swaminathan, Vikhram V; Shannon, Mark A; Bashir, Rashid
2015-04-01
Dielectrophoretic separation of particles finds a variety of applications in the capture of species such as cells, viruses, proteins, DNA from biological systems, as well as other organic and inorganic contaminants from water. The ability to capture particles is constrained by poor volumetric scaling of separation force with respect to particle diameter, as well as the weak penetration of electric fields in the media. In order to improve the separation of sub-micron colloids, we present a scheme based on multiple interdigitated electrode arrays under mixed AC/DC bias. The use of high frequency longitudinal AC bias breaks the shielding effects through electroosmotic micromixing to enhance electric fields through the electrolyte, while a transverse DC bias between the electrode arrays enables penetration of the separation force to capture particles from the bulk of the microchannel. We determine the favorable biasing conditions for field enhancement with the help of analytical models, and experimentally demonstrate the improved capture from sub-micron colloidal suspensions with the mixed AC/DC electrostatic excitation scheme over conventional AC-DEP methods.
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Power-MOSFET Voltage Regulator
NASA Technical Reports Server (NTRS)
Miller, W. N.; Gray, O. E.
1982-01-01
Ninety-six parallel MOSFET devices with two-stage feedback circuit form a high-current dc voltage regulator that also acts as fully-on solid-state switch when fuel-cell out-put falls below regulated voltage. Ripple voltage is less than 20 mV, transient recovery time is less than 50 ms. Parallel MOSFET's act as high-current dc regulator and switch. Regulator can be used wherever large direct currents must be controlled. Can be applied to inverters, industrial furnaces photovoltaic solar generators, dc motors, and electric autos.
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Optical Properties of Blow-Off Particulates.
1984-02-29
examination of the SEM data in Sec- tion 3, for the particulates vary greatly in size, structure and melting points . Table 4. Refractive indices of minerals...of the balance. With no dc field applied the particle oscillates about a point below the midplane of the balance. When a dc field is applied to offset...electric field near the null point (midplane) of the balance is given by V dc Edc,z x- (11) where C is a geometrical constant which takes into account the
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Jeffery, A.; Elmquist, R. E.; Cage, M. E.
1995-01-01
Precision tests verify the dc equivalent circuit used by Ricketts and Kemeny to describe a quantum Hall effect device in terms of electrical circuit elements. The tests employ the use of cryogenic current comparators and the double-series and triple-series connection techniques of Delahaye. Verification of the dc equivalent circuit in double-series and triple-series connections is a necessary step in developing the ac quantum Hall effect as an intrinsic standard of resistance. PMID:29151768
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NASA Technical Reports Server (NTRS)
Woods, J. M. (Inventor)
1973-01-01
An electrical power distribution system is described for use in providing different dc voltage levels. A circuit is supplied with DC voltage levels and commutates pulses for timed intervals onto a pair of distribution wires. The circuit is driven by a command generator which places pulses on the wires in a timed sequence. The pair of wires extend to voltage strippers connected to the various loads. The voltage strippers each respond to the pulse dc levels on the pair of wires and form different output voltages communicated to each load.
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Activity of Electrical Current in Experimental Propionibacterium acnes Foreign-Body Osteomyelitis.
Schmidt-Malan, Suzannah M; Brinkman, Cassandra L; Greenwood-Quaintance, Kerryl E; Karau, Melissa J; Mandrekar, Jayawant N; Patel, Robin
2017-02-01
Foreign-body-associated infections are often difficult to treat, given that the associated microorganisms are in a biofilm state. Previously, we showed that a low-amperage direct electrical current (DC) reduces Propionibacterium acnes biofilms formed on implant-associated materials in vitro In this study, low-amperage DC was compared to ceftriaxone treatment or no treatment in a novel rat femur model of foreign-body osteomyelitis. A platinum implant seeded with a P. acnes biofilm (10 7 CFU/cm 2 ) and 10 9 CFU of planktonic P. acnes was placed in the femoral medullary cavity. One week later, rats were assigned to one of three treatment groups: no treatment, ceftriaxone treatment, or 200-μA-DC treatment. After 2 weeks of treatment, there were fewer bacteria in the bones of the ceftriaxone group (3.06 log 10 CFU/g of bone [P = 0.0209]) and the 200-μA-DC group (0.5 log 10 CFU/g [P = 0.0015]) than in those of the control group (6.58 log 10 CFU/g). The DC-exposed animals exhibited fewer bacteria than the ceftriaxone-treated animals (P = 0.0330). There were fewer bacteria on the implanted wires in the groups treated with ceftriaxone (0.1 log 10 CFU/cm 2 ) or a 200-μA DC (0.1 log 10 CFU/cm 2 ) than in the control group (2.53 log 10 CFU/cm 2 [P, 0.0003 for both comparisons]). Low-amperage DC may be useful for treating, or aiding in the treatment of, foreign-body infections caused by P. acnes. Copyright © 2017 American Society for Microbiology.
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ERIC Educational Resources Information Center
BUSHNELL, DAVID S.
A SURVEY OF THE MEMBERS OF LOCAL 617, INTERNATIONAL BROTHERHOOD OF ELECTRICAL WORKERS, SAN MATEO COUNTY, CALIFORNIA, REVEALED THAT THE ELECTRICIANS FELT THEY NEEDED--(1) A REVIEW OF THE FUNDAMENTALS OF ELECTRICITY AND ELECTRIC CIRCUIT THEORY, BOTH FOR AC AND DC CURRENTS, (2) NEW APPLICATIONS AND USE OF ELECTRICAL TEST EQUIPMENT, (3) THE ABILITY TO…
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NASA Astrophysics Data System (ADS)
Dey, Arka; Dhar, Joydeep; Sil, Sayantan; Jana, Rajkumar; Ray, Partha Pratim
2018-04-01
In this report, bias voltage-dependent dielectric and electron transport properties of ZnS nanoparticles were discussed. ZnS nanoparticles were synthesized by introducing a modified hydrothermal process. The powder XRD pattern indicates the phase purity, and field emission scanning electron microscope image demonstrates the morphology of the synthesized sample. The optical band gap energy (E g = 4.2 eV) from UV measurement explores semiconductor behavior of the synthesized material. The electrical properties were performed at room temperature using complex impedance spectroscopy (CIS) technique as a function of frequency (40 Hz-10 MHz) under different forward dc bias voltages (0-1 V). The CIS analysis demonstrates the contribution of bulk resistance in conduction mechanism and its dependency on forward dc bias voltages. The imaginary part of the impedance versus frequency curve exhibits the existence of relaxation peak which shifts with increasing dc forward bias voltages. The dc bias voltage-dependent ac and dc conductivity of the synthesized ZnS was studied on thin film structure. A possible hopping mechanism for electrical transport processes in the system was investigated. Finally, it is worth to mention that this analysis of bias voltage-dependent dielectric and transport properties of as-synthesized ZnS showed excellent properties for emerging energy applications.
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Results of Electrical Resistivity Data Collected near the Town of Guernsey, Platte County, Wyoming
McDougal, Robert R.; Abraham, Jared D.; Bisdorf, Robert J.
2004-01-01
As part of a study to investigate subsurface geologic conditions as they relate to ground-water flow in an abandoned landfill near the town of Guernsey, Wyoming, geophysical direct current (DC) resistivity data were collected. Eight vertical resistivity soundings and eight horizontal resistivity profiles were made using single channel and multi-channel DC instruments. Data collected in the field were converted from apparent resistivity to inverted resistivity with depth using a numerical inversion of the data. Results of the inverted resistivity data are presented as horizontal profiles and as profiles derived from the combined horizontal profile and vertical sounding data. The data sets collected using the single-channel and multi-channel DC systems provided for the resistivity investigation to extend to greater depth. Similarity of the electrical properties of the bedrock formations made interpretation of the resistivity profiles more difficult. High resistivity anomalies seen in the profiles are interpreted as quartzite lenses and as limestone or metadolomite structures in the eastern part of the study area. Terrace gravels were mapped as resistive where dry and less resistive in the saturated zone. The DC resistivity methods used in this study illustrate that multi-electrode DC resistivity surveying and more traditional methodologies can be merged and used to efficiently map anomalies of hydrologic interest in geologically complex terrain.
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A technological review on electric vehicle DC charging stations using photovoltaic sources
NASA Astrophysics Data System (ADS)
Youssef, Cheddadi; Fatima, Errahimi; najia, Es-sbai; Chakib, Alaoui
2018-05-01
Within the next few years, Electrified vehicles are destined to become the essential component of the transport field. Consequently, the charging infrastructure should be developed in the same time. Among this substructure, Charging stations photovoltaic-assisted are attracting a substantial interest due to increased environmental awareness, cost reduction and rise in efficiency of the PV modules. The intention of this paper is to review the technological status of Photovoltaic–Electric vehicle (PV-EV) charging stations during the last decade. The PV-EV charging station is divided into two categories, which are PV-grid and PV-standalone charging systems. From a practical point view, the distinction between the two architectures is the bidirectional inverter, which is added to link the station to the smart grid. The technological infrastructure includes the common hardware components of every station, namely: PV array, dc-dc converter provided with MPPT control, energy storage unit, bidirectional dc charger and inverter. We investigate, compare and evaluate many valuable researches that contain the design and control of PV-EV charging system. Additionally, this concise overview reports the studies that include charging standards, the power converters topologies that focus on the adoption of Vehicle-to grid technology and the control for both PV–grid and PV standalone DC charging systems.
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Grain Boundary Resistivity of Yttria-Stabilized Zirconia at 1400°C
Wang, J.; Du, A.; Yang, Di; ...
2013-01-01
Tmore » he grain size dependence of the bulk resistivity of 3 mol% yttria-stabilized zirconia at 1400°C was determined from the effect of a dc electric field E a = 18.1 V/cm on grain growth and the corresponding electric current during isothermal annealing tests. Employing the brick layer model, the present annealing test results were in accordance with extrapolations of the values obtained at lower temperature employing impedance spectroscopy and 4-point-probe dc. he combined values give that the magnitude of the grain boundary resistivity ρ b = 133 ohm-cm. he electric field across the grain boundary width was 28–43 times the applied field for the grain size and current ranges in the present annealing test.« less
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DC Stark addressing for quantum memory in Tm:YAG
NASA Astrophysics Data System (ADS)
Gerasimov, Konstantin; Minnegaliev, Mansur; Urmancheev, Ravil; Moiseev, Sergey
2017-10-01
We observed a linear DC Stark effect for 3H6 - 3H4 optical transition of Tm3+ ions in Y3Al5O12. We observed that application of electric field pulse suppresses the two-pulse photon echo signal. If we then apply a second electric pulse of opposite polarity the echo signal is restored again, which indicates the linear nature of the observed effect. The effect is present despite the D2 symmetry of the Tm3+ sites that prohibits a linear Stark effect. Experimental data analysis shows that the observed electric field influence can be attributed to defects that break the local crystal field symmetry near Tm3+ ions. Using this effect we demonstrate selective retrieval of light pulses in two-pulse photon echo.
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Dynamics of runaway tails with time-dependent sub-Dreicer dc fields in magnetized plasmas
NASA Technical Reports Server (NTRS)
Moghaddam-Taaheri, E.; Vlahos, L.
1987-01-01
The evolution of runaway tails driven by sub-Dreicer time-dependent dc fields in a magnetized plasma are studied numerically using a quasi-linear code based on the Ritz-Galerkin method and finite elements. It is found that the runaway tail maintained a negative slope during the dc field increase. Depending on the values of the dc electric field at t = 0 and the electron gyrofrequency to the plasma frequency ratio the runaway tail became unstable to the anomalous Doppler resonance or remained stable before the saturation of the dc field at some maximum value. The systems that remained stable during this stage became unstable to the anomalous Doppler or the Cerenkov resonances when the dc field was kept at the saturation level or decreased. Once the instability is triggered, the runaway tail is isotropized.
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NASA Astrophysics Data System (ADS)
Zhou, Ning; Yang, Jia; Cheng, Zheng; Chen, Bo; Su, Yong Chun; Shu, Zhan; Zou, Jin
2017-06-01
Solar photovoltaic power generation is the power generation using solar cell module converting sunlight into DC electric energy. In the paper an equivalent model of solar photovoltaic power generation system is built in RTDS. The main circuit structure of the two-stage PV grid-connected system consists of the DC-DC, DC-AC circuit. The MPPT (Maximum Power Point Tracking) control of the PV array is controlled by adjusting the duty ratio of the DC-DC circuit. The proposed control strategy of constant voltage/constant reactive power (V/Q) control is successfully implemented grid-connected control of the inverter when grid-connected operation. The closed-loop experiment of islanding protection device of photovoltaic power plant on RTDS, verifies the correctness of the simulation model, and the experimental verification can be applied to this type of device.
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Use of electricity to sedate Lake Trout for intracoelomic implantation of electronic transmitters
Faust, Matthew D.; Vandergoot, Christopher; Hostnik, Eric T.; Binder, Thomas R.; Mida Hinderer, Julia L.; Ives, Jessica T.; Krueger, Charles C.
2017-01-01
Use of telemetry data to inform fisheries conservation and management is becoming increasingly common; as such, fish typically must be sedated before surgical implantation of transmitters into the coelom. Given that no widely available, immediate-release chemical sedative currently exists in North America, we investigated the feasibility of using electricity to sedate Lake Trout Salvelinus namaycush long enough for an experienced surgeon to implant an electronic transmitter (i.e., 180 s). Specifically, our study objectives were to determine (1) whether some combination of electrical waveform characteristics (i.e., duty cycle, frequency, voltage, and pulse type) could sedate Lake Trout for at least 180 s; and (2) whether Lake Trout that were sequentially exposed to continuous DC and pulsed DC had greater rates of spinal injury and short-term mortality than control fish. A Portable Electrosedation System unit was used to sedate hatchery and wild Lake Trout. Dual-frequency pulsed-DC and two-stage approaches successfully sedated Lake Trout and had similar induction and recovery times. Lake Trout sedated using the two-stage approach did not have survival rates or spinal abnormalities that were significantly different from those of control fish. We concluded that electricity was a viable alternative to chemical sedatives for sedating Lake Trout before surgical implantation of an electronic transmitter, but we suggest that Lake Trout and other closely related species (e.g., Arctic Char Salvelinus alpinus) may require morphotype-specific electrical waveforms due to their morphological diversity.
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2012-03-09
equation is a product of a complex basis vector in Jackson and a linear combination of plane wave functions. We convert both the amplitudes and the...wave function arguments from complex scalars to complex vectors . This conversion allows us to separate the electric field vector and the imaginary...magnetic field vector , because exponentials of imaginary scalars convert vectors to imaginary vectors and vice versa, while ex- ponentials of imaginary
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Description of a MIL-STD-1553B Data Bus Ada Driver for the LeRC EPS Testbed
NASA Technical Reports Server (NTRS)
Mackin, Michael A.
1995-01-01
This document describes the software designed to provide communication between control computers in the NASA Lewis Research Center Electrical Power System Testbed using MIL-STD-1553B. The software drivers are coded in the Ada programming language and were developed on a MSDOS-based computer workstation. The Electrical Power System (EPS) Testbed is a reduced-scale prototype space station electrical power system. The power system manages and distributes electrical power from the sources (batteries or photovoltaic arrays) to the end-user loads. The electrical system primary operates at 120 volts DC, and the secondary system operates at 28 volts DC. The devices which direct the flow of electrical power are controlled by a network of six control computers. Data and control messages are passed between the computers using the MIL-STD-1553B network. One of the computers, the Power Management Controller (PMC), controls the primary power distribution and another, the Load Management Controller (LMC), controls the secondary power distribution. Each of these computers communicates with two other computers which act as subsidiary controllers. These subsidiary controllers are, in turn, connected to the devices which directly control the flow of electrical power.
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Negative Capacitance in BaTiO3/BiFeO3 Bilayer Capacitors.
Hou, Ya-Fei; Li, Wei-Li; Zhang, Tian-Dong; Yu, Yang; Han, Ren-Lu; Fei, Wei-Dong
2016-08-31
Negative capacitances provide an approach to reduce heat generations in field-effect transistors during the switch processes, which contributes to further miniaturization of the conventional integrated circuits. Although there are many studies about negative capacitances using ferroelectric materials, the direct observation of stable ferroelectric negative capacitances has rarely been reported. Here, we put forward a dc bias assistant model in bilayer capacitors, where one ferroelectric layer with large dielectric constant and the other ferroelectric layer with small dielectric constant are needed. Negative capacitances can be obtained when external dc bias electric fields are larger than a critical value. Based on the model, BaTiO3/BiFeO3 bilayer capacitors are chosen as study objects, and negative capacitances are observed directly. Additionally, the upward self-polarization effect in the ferroelectric layer reduces the critical electric field, which may provide a method for realizing zero and/or small dc bias assistant negative capacitances.
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Optically tunable Quincke rotation of a nanometer-thin oblate spheroid
NASA Astrophysics Data System (ADS)
Gu, Yu; Zeng, Haibo
2017-08-01
Ever since the discovery of Quincke rotation (spontaneous rotation of a particle in fluid under a dc electric field) more than 100 years ago [G. Quincke, Ann. Phys. (Leipzig) 295, 417 (1896), 10.1002/andp.18962951102], the strength of the dc field has been the only external parameter to actively tune the rotation speed. In this paper we theoretically propose an optically tunable Quincke rotor exploiting the photoconductivity of a semiconducting nanometer-thin oblate spheroid. A full analysis of the instability of the Quincke rotation reveals that, unlike a prolate spheroid, no bistability is possible in such a dynamical system. In addition, the required material property and the strength of the dc electric field needed to realize the rotation are also elucidated. It is also predicted that light can be used to tune the spinning speed or simply turn on and off the Quincke rotation very effectively.
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Stamp transferred suspended graphene mechanical resonators for radio frequency electrical readout.
Song, Xuefeng; Oksanen, Mika; Sillanpää, Mika A; Craighead, H G; Parpia, J M; Hakonen, Pertti J
2012-01-11
We present a simple micromanipulation technique to transfer suspended graphene flakes onto any substrate and to assemble them with small localized gates into mechanical resonators. The mechanical motion of the graphene is detected using an electrical, radio frequency (RF) reflection readout scheme where the time-varying graphene capacitor reflects a RF carrier at f = 5-6 GHz producing modulation sidebands at f ± f(m). A mechanical resonance frequency up to f(m) = 178 MHz is demonstrated. We find both hardening/softening Duffing effects on different samples and obtain a critical amplitude of ~40 pm for the onset of nonlinearity in graphene mechanical resonators. Measurements of the quality factor of the mechanical resonance as a function of dc bias voltage V(dc) indicates that dissipation due to motion-induced displacement currents in graphene electrode is important at high frequencies and large V(dc). © 2011 American Chemical Society
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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.
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NASA Astrophysics Data System (ADS)
Pan, Huei-Jyuan; Wang, Ruei-Lin; Xiao, Jian-Long; Chang, Yu-Jen; Cheng, Ji-Yen; Chen, Yun-Ru; Lee, Chau-Hwang
2014-01-01
The membrane roughness of Neuro-2a neroblastoma cells is measured by using noninterferometric wide-field optical profilometry. The cells are treated with the fibril and oligomer conformers of amyloid-beta (Aβ) 42, which is a peptide of 42 amino acids related to the development of Alzheimer's disease. We find that both the Aβ42 fibrils and Aβ42 oligomers reduced the cell membrane roughness, but the effect of Aβ42 oligomers was faster and stronger than that of the fibrils. We also apply direct-current electric field (dcEF) stimulations on the cells. A dcEF of 300 mV/mm can increase the membrane roughness under the treatment of Aβ42. These results suggest that Aβ42 can decrease the membrane compliance of live neuroblastoma cells, and dcEFs may counteract this effect.
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Effects of sintering temperature on electrical properties of sheep enamel hydroxyapatite
NASA Astrophysics Data System (ADS)
Dumludag, F.; Gunduz, O.; Kılıc, O.; Kılıc, B.; Ekren, N.; Kalkandelen, C.; Oktar, F. N.
2017-12-01
Bioceramics, especially calcium phosphate based bioceramics, whose examples are hydroxyapatite, and calcium phosphate powders have been widely used in the biomedical engineering applications. Hydroxyapatite (HA) is one of the most promising biomaterials, which are derived from natural sources, chemical method, animal like dental enamel and corals. The influence of sintering temperature on the electrical properties (i.e. DC conductivity, AC conductivity) of samples of sintered sheep enamel (SSSE) was studied in air and in vacuum ambient at room temperature. The sheep enamel were sintered at varying temperatures between 1000°C and 1300°C. DC conductivity results revealed that while dc conductivity of the SSSE decreases with increasing the sintering temperature in air ambient the values increased with increasing the sintering temperature in vacuum ambient. AC conductivity measurements were performed in the frequency range of 40 Hz - 105 Hz. The results showed that ac conductivity values decrease with increasing the sintering temperature.
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Do dielectric nanostructures turn metallic in high-electric dc fields?
Silaeva, E P; Arnoldi, L; Karahka, M L; Deconihout, B; Menand, A; Kreuzer, H J; Vella, A
2014-11-12
Three-dimensional dielectric nanostructures have been analyzed using field ion microscopy (FIM) to study the electric dc field penetration inside these structures. The field is proved to be screened within a few nanometers as theoretically calculated taking into account the high-field impact ionization process. Moreover, the strong dc field of the order of 0.1 V/Å at the surface inside a dielectric nanostructure modifies its band structure leading to a strong band gap shrinkage and thus to a strong metal-like optical absorption near the surface. This metal-like behavior was theoretically predicted using first-principle calculations and experimentally proved using laser-assisted atom probe tomography (APT). This work opens up interesting perspectives for the study of the performance of all field-effect nanodevices, such as nanotransistor or super capacitor, and for the understanding of the physical mechanisms of field evaporation of dielectric nanotips in APT.
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An Inverter Packaging Scheme for an Integrated Segmented Traction Drive System
DOE Office of Scientific and Technical Information (OSTI.GOV)
Su, Gui-Jia; Tang, Lixin; Ayers, Curtis William
The standard voltage source inverter (VSI), widely used in electric vehicle/hybrid electric vehicle (EV/HEV) traction drives, requires a bulky dc bus capacitor to absorb the large switching ripple currents and prevent them from shortening the battery s life. The dc bus capacitor presents a significant barrier to meeting inverter cost, volume, and weight requirements for mass production of affordable EVs/HEVs. The large ripple currents become even more problematic for the film capacitors (the capacitor technology of choice for EVs/HEVs) in high temperature environments as their ripple current handling capability decreases rapidly with rising temperatures. It is shown in previous workmore » that segmenting the VSI based traction drive system can significantly decrease the ripple currents and thus the size of the dc bus capacitor. This paper presents an integrated packaging scheme to reduce the system cost of a segmented traction drive.« less
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DC isolation and protection system and circuit
NASA Technical Reports Server (NTRS)
Wagner, Charles A. (Inventor); Kellogg, Gary V. (Inventor)
1991-01-01
A precision analog electronic circuit that is capable of sending accurate signals to an external device that has hostile electric characteristics, including the presence of very large common mode voltages. The circuit is also capable of surviving applications of normal mode overvoltages of up to 120 VAC/VDC for unlimited periods of time without damage or degradation. First, the circuit isolates the DC signal output from the computer. Means are then provided for amplifying the isolated DC signal. Further means are provided for stabilizing and protecting the isolating and amplifying means, and the isolated and amplified DC signal which is output to the external device, against overvoltages and overcurrents.
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Gene expression of human lung cancer cell line CL1-5 in response to a direct current electric field.
Huang, Ching-Wen; Chen, Huai-Yi; Yen, Meng-Hua; Chen, Jeremy J W; Young, Tai-Horng; Cheng, Ji-Yen
2011-01-01
Electrotaxis is the movement of adherent living cells in response to a direct current (dc) electric field (EF) of physiological strength. Highly metastatic human lung cancer cells, CL1-5, exhibit directional migration and orientation under dcEFs. To understand the transcriptional response of CL1-5 cells to a dcEF, microarray analysis was performed in this study. A large electric-field chip (LEFC) was designed, fabricated, and used in this study. CL1-5 cells were treated with the EF strength of 0 mV/mm (the control group) and 300 mV/mm (the EF-treated group) for two hours. Signaling pathways involving the genes that expressed differently between the two groups were revealed. It was shown that the EF-regulated genes highly correlated to adherens junction, telomerase RNA component gene regulation, and tight junction. Some up-regulated genes such as ACVR1B and CTTN, and some down-regulated genes such as PTEN, are known to be positively and negatively correlated to cell migration, respectively. The protein-protein interactions of adherens junction-associated EF-regulated genes suggested that platelet-derived growth factor (PDGF) receptors and ephrin receptors may participate in sensing extracellular electrical stimuli. We further observed a high percentage of significantly regulated genes which encode cell membrane proteins, suggesting that dcEF may directly influence the activity of cell membrane proteins in signal transduction. In this study, some of the EF-regulated genes have been reported to be essential whereas others are novel for electrotaxis. Our result confirms that the regulation of gene expression is involved in the mechanism of electrotactic response.
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Performance power evaluation of DC fan cooling system for PV panel by using ANSYS CFX
NASA Astrophysics Data System (ADS)
Syafiqah, Z.; Amin, N. A. M.; Irwan, Y. M.; Irwanto, M.; Leow, W. Z.; Amelia, A. R.
2017-09-01
A research has been conducted to find the optimum combination for DC fan air cooling system of photovoltaic (PV) panel. During normal operation of PV panel, it is estimated that only 15 % of solar radiation is converted into electrical energy. Meanwhile, the rest of the solar radiation is converted into heat energy which affects the performance of the PV panel. Therefore, the aim of this research is to investigate the performance power evaluation of DC fan cooling system for PV panel by using ANSYS CFX. The effect of airflow configuration of DC fan has been investigated. This is to analyze whether the airflow circulation of DC fan cause a change towards the maximum temperature of PV panel. Besides, the impact of varying number of DC fans attached at the back of PV panel is evaluated. The result of airflow circulation of DC fan has been discussed. Meanwhile, with the increment number of DC fans, the PV panel temperature drops significantly. As a conclusion, the optimum number of DC fans is two with the combination of inlet airflow.
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Comparison of Whole Eye vs. First-Surface Astigmatism in Down Syndrome
Knowlton, Rachel; Marsack, Jason D.; Leach, Norman E.; Herring, Ralph J.; Anderson, Heather A.
2016-01-01
Purpose Individuals with Down syndrome (DS) have structural differences in the cornea and lens, as compared to the general population. This study investigates objectively measured refractive and corneal astigmatism, as well as calculated internal astigmatism in subjects with and without DS. Methods Refractive (Grand Seiko autorefraction) and anterior corneal astigmatism (difference between steep and flat keratometry obtained with Zeiss Atlas corneal topography) were measured in 128 subjects with DS (mean age = 24.8±8.7 yrs) and 137 controls without DS (mean age = 24.9±9.9 yrs), with 1 eye randomly selected for analysis per subject. Refractive astigmatism and corneal astigmatism were converted to vector notation (J0, J45) to calculate internal astigmatism (Refractive – Corneal) and then converted back to minus cylinder form. Results Mean refractive astigmatism was significantly greater in subjects with DS than controls (−1.94±1.30DC vs −0.66±0.60DC, t=−10.16, p<0.001), as was mean corneal astigmatism (1.70±1.04DC vs 1.02±0.63DC, t=6.38, p<0.001) and mean internal astigmatism (−1.07±0.68DC vs −0.77±0.41DC, t=−4.21, p<0.001). A positive linear correlation between corneal and refractive astigmatism was observed for both study populations for both the J0 and J45 vectors (p<0.001 for all comparisons, R2 range = 0.31 to 0.74). The distributions of astigmatism orientation differed significantly between the two study populations when compared across all three types of astigmatism (Chi-Square, p<0.001). Conclusions This study demonstrates that corneal astigmatism is predictive of overall refractive astigmatism in individuals with DS, as it is in the general population. The greater magnitudes of astigmatism and wider variation of astigmatism orientation in individuals with DS for refractive, corneal, and calculated internal astigmatism is likely attributable to previously reported differences in the structure of the cornea and internal optical components of the eye from that of the general population. PMID:26002006
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Rotating electrical machines: Poynting flow
NASA Astrophysics Data System (ADS)
Donaghy-Spargo, C.
2017-09-01
This paper presents a complementary approach to the traditional Lorentz and Faraday approaches that are typically adopted in the classroom when teaching the fundamentals of electrical machines—motors and generators. The approach adopted is based upon the Poynting vector, which illustrates the ‘flow’ of electromagnetic energy. It is shown through simple vector analysis that the energy-flux density flow approach can provide insight into the operation of electrical machines and it is also shown that the results are in agreement with conventional Maxwell stress-based theory. The advantage of this approach is its complementary completion of the physical picture regarding the electromechanical energy conversion process—it is also a means of maintaining student interest in this subject and as an unconventional application of the Poynting vector during normal study of electromagnetism.
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NASA Technical Reports Server (NTRS)
Santiago, Walter; Birchenough, Arthur G.
2006-01-01
Stirling engine converters are being considered as potential candidates for high power energy conversion systems required by future NASA explorations missions. These types of engines typically contain two major moving parts, the displacer and the piston, in which a linear alternator is attached to the piston to produce a single phase sinusoidal waveform at a specific electric frequency. Since all Stirling engines perform at low electrical frequencies (less or equal to 100 Hz), space explorations missions that will employ these engines will be required to use DC power management and distribution (PMAD) system instead of an AC PMAD system to save on space and weight. Therefore, to supply such DC power an AC to DC converter is connected to the Stirling engine. There are two types of AC to DC converters that can be employed, a passive full bridge diode rectifier and an active switching full bridge rectifier. Due to the inherent line inductance of the Stirling Engine-Linear Alternator (SE-LA), their sinusoidal voltage and current will be phase shifted producing a power factor below 1. In order to keep power the factor close to unity, both AC to DC converters topologies will implement power factor correction. This paper discusses these power factor correction methods as well as their impact on overall mass for exploration applications. Simulation results on both AC to DC converters topologies with power factor correction as a function of output power and SE-LA line inductance impedance are presented and compared.
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NASA Astrophysics Data System (ADS)
Pervaiz, Erum; Gul, I. H.
2013-10-01
Aluminum and chromium substituted Co-Ni spinel nanoferrites were prepared by sol-gel auto combustion method. Structural parameters along with electrical and magnetic properties have been investigated in the present work. Crystallite sizes of nano ferrite estimated from the peak (311) lies in the range of 13-21 nm ±2 nm and compared with crystallite sizes calculated from Williamsons-Hall plots. DC electrical resistivity variations due to the concentration of aluminum and chromium in the host ferrite have been measured from 368 K to 573 K. Increase in the room temperature DC electrical resistivity was observed up to a concentration x=0.2 and then decreases for x >0.2. Dielectric parameters (real and imaginary part of complex permittivity, dielectric loss tangent) were studied as a function of frequency (20 Hz-5 MHz) and a decrease in the dielectric parameters was observed due to substitution of nickel, aluminum and chromium ions in cobalt nanoferrites. AC conductivity, complex impedance and complex electrical modulus were studied as a function of frequency for the conduction and relaxation mechanisms in the present ferrite system. Saturation magnetization, coercivity, canting angles and magneto crystalline anisotropy variations with composition were observed and presented for the present ferrites under an applied magnetic field of 10 kOe at room temperature. It was found that both magnetization and coercivity decreases with increase in the concentration of aluminum and chromium along with a decrease in the anisotropy parameters. High DC resistivity with low dielectric parameters of the present nanoferrites make them suitable for high frequency and electromagnetic wave absorbing devices. High purity mixed Co-Ni-Al-Cr nanoferrites have been prepared by sol-gel auto combustion method. DC electrical resistivity increases due to substitution of Al3+ and Cr3+. Complex permittivity decrease for Co-Ni-Al-Cr nanoferrites. Detailed AC response analysis has been presented for mixed Co-Ni-Al-Cr nanoferrites. Magnetization and coercively reduces for Al3+ and Cr3+ doped Co-Ni ferrite nanoparticles showing that material is becoming soft magnetic.
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Electrical Anomalies Observed During DC3
NASA Technical Reports Server (NTRS)
Lang, Timothy J.; Rutledge, Steven A.; Dolan, Brenda; Krehbiel, Paul; Rison, William; Lindsey, Daniel T.; Lyons, Walt
2013-01-01
The primary scientific goals of DC3 involved improving our understanding of the chemical impacts of thunderstorms and their anvils. However, the Colorado domain provided opportunities to study other interesting phenomena, including the potential impacts of smoke ingestion on convection and thunderstorms, electrification processes in smoke plumes and pyrocumulonimbus clouds, and the production of sprites by unconventional thunderstorm.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-06-08
... Activities; Submission to OMB for Review and Approval; Comment Request; NESHAP for Area Sources: Electric Arc... preferred method), or by e-mail to [email protected] , or by mail to: EPA Docket Center (EPA/DC..., 1200 Pennsylvania Avenue, NW., Washington, DC 20460, and (2) OMB at: Office of Information and...
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Acoustic resonance of outer-rotor brushless dc motor for air-conditioner fan
NASA Astrophysics Data System (ADS)
Lee, Hong-Joo; Chung, Shi-Uk; Hwang, Sang-Moon
2008-04-01
Generation of acoustic noise in electric motor is an interacting combination of mechanical and electromagnetic sources. In this paper, a brushless dc motor for air-conditioner fan is analyzed by finite element method to identify noise source, and the analysis results are verified by experiments, and sensitivity analysis is performed by design of experiments.
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75 FR 57761 - North American Electric Reliability Corporation; Notice of Filing September 14, 2010.
Federal Register 2010, 2011, 2012, 2013, 2014
2010-09-22
... request for approval of implementation plans for Generator Owners and Generator Operators of nuclear power..., 888 First Street, NE., Washington, DC 20426. This filing is accessible on-line at http://www.ferc.gov... Washington, DC. There is an ``eSubscription'' link on the Web site that enables subscribers to receive e-mail...
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Summary of electric vehicle dc motor-controller tests
NASA Technical Reports Server (NTRS)
Mcbrien, E. F.; Tryon, H. B.
1982-01-01
The differences in the performance of dc motors are evaluated when operating with chopper type controllers, and when operating on direct current. The interactions between the motor and the controller which cause these differences are investigated. Motor-controlled tests provided some of the data the quantified motor efficiency variations for both ripple free and chopper modes of operation.
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USDA-ARS?s Scientific Manuscript database
A 3rd-generation AC-DC electrical penetration graph (EPG) monitor was used to study feeding behaviors of pre-reproductive adult Lygus lineolaris (Hemiptera: Miridae) on pinhead (<3mm) cotton squares, applying different signal voltages at several input impedances. The AC-DC monitor allows a user to s...
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Decoy receptor 3 enhances tumor progression via induction of tumor-associated macrophages.
Tai, Shyh-Kuan; Chang, Hsin-Chuan; Lan, Keng-Li; Lee, Chun-Ting; Yang, Chih-Ya; Chen, Nien-Jung; Chou, Teh-Ying; Tarng, Der-Cherng; Hsieh, Shie-Liang
2012-03-01
Tumor-associated macrophages (TAMs) are the major component of tumor-infiltrating leukocytes. TAMs are heterogeneous, with distinct phenotypes influenced by the microenvironment surrounding tumor tissues. Decoy receptor 3 (DcR3), a member of the TNFR superfamily, is overexpressed in tumor cells and is capable of modulating host immunity as either a neutralizing decoy receptor or an effector molecule. Upregulation of DcR3 has been observed to correlate with a poor prognosis in various cancers. However, the mechanisms underlying the DcR3-mediated tumor-promoting effect remain unclear. We previously demonstrated that DcR3 modulates macrophage activation toward an M2-like phenotype in vitro and that DcR3 downregulates MHC class II expression in TAMs via epigenetic control. To investigate whether DcR3 promotes tumor growth, CT26-DcR3 stable transfectants were established. Compared with the vector control clone, DcR3-transfectants grew faster and resulted in TAM infiltration. We further generated CD68 promoter-driven DcR3 transgenic (Tg) mice to investigate tumor growth in vivo. Compared with wild-type mice, macrophages isolated from DcR3-Tg mice displayed higher levels of IL-10, IL-1ra, Ym1, and arginase activity, whereas the expression of IL-12, TNF-α, IL-6, NO, and MHC class II was downregulated. Significantly enhanced tumor growth and spreading were observed in DcR3-Tg mice, and the enhanced tumor growth was abolished by arginase inhibitor N-ω-hydroxy-l-norarginine and histone deacetylase inhibitor sodium valproate. These results indicated that induction of TAMs is an important mechanism for DcR3-mediated tumor progression. Our findings also suggest that targeting DcR3 might help in the development of novel treatment strategies for tumors with high DcR3 expression.
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Hakoda, Masaru; Hirota, Yusuke
2013-09-01
The purpose of this study is to develop a system analyzing cell activity by the dielectrophoresis method. Our previous studies revealed a correlation between the growth activity and dielectric property (Re[K(ω)]) of mouse hybridoma 3-2H3 cells using dielectrophoretic levitation. Furthermore, it was clarified that the differentiation activity of many stem cells could be evaluated by the Re[K(ω)] without differentiation induction. In this paper, 3-2H3 cells exposed to an alternating current (AC) electric field or a direct current (DC) electric field were cultivated, and the influence of damage by the electric field on the growth activity of the cells was examined. To evaluate the activity of the cells by measuring the Re[K(ω)], the correlation between the growth activity and the Re[K(ω)] of the cells exposed to the electric field was examined. The relations between the cell viability, growth activity, and Re[K(ω)] in the cells exposed to the AC electric field were obtained. The growth activity of the cells exposed to the AC electric field could be evaluated by the Re[K(ω)]. Furthermore, it was found that the adverse effects of the electric field on the cell viability and the growth activity were smaller in the AC electric field than the DC electric field.
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1987-03-01
compound promises to reduce weight of future permanent magnet motors by 20 to 30 percent; a similar reduction is expected in size (approximately 20...drive systems. The AC permanent magnet (brushless DC motor) is rapidly evolving and will replace most electrically excited machines. Permanent magnet motors using
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Toda, Hiroshi; Itoh, Nobuya
2017-01-01
The novel cryptic pKPAL3 plasmid was isolated from the Gram-positive microorganism Kocuria palustris IPUFS-1 and characterized in detail. pKPAL3 is a circular plasmid that is 4,443 bp in length. Open reading frame (ORF) and homology search analyses indicated that pKPAL3 possesses four ORFs; however, there were no replication protein coding genes predicted in the plasmid. Instead, there were two nucleotide sequence regions that showed significant identities with untranslated regions of K. rhizophila DC2201 (NBRC 103217) genomic sequences, and these sequences were essential for autonomous replication of pKPAL3 in Kocuria cells. Based on these findings, we constructed the novel Escherichia coli–Kocuria shuttle vectors pKITE301 (kanamycin resistant) and pKITE303 (thiostrepton resistant) from pKPAL3. The copy numbers of the constructed shuttle vectors were estimated to be 20 per cell, and they exhibited low segregation stability in Kocuria transformant cells in the absence of antibiotics. Moreover, constructed vectors showed compatibility with the other K. rhizophila shuttle vector pKITE103. We successfully expressed multiple heterologous genes, including the styrene monooxygenase gene from Rhodococcus sp. ST-10 (rhsmo) and alcohol dehydrogenase gene from Leifsonia sp. S749 (lsadh), in K. rhizophila DC2201 using the pKITE301P and pKITE103P vectors under the control of the glyceraldehyde 3-phosphate dehydrogenase (gapdh) promotor. The RhSMO–LSADH co-expressing K. rhizophila was used as a biocatalyst in an organic solvent–water biphasic reaction system to efficiently convert styrene into (S)-styrene oxide with 99% ee in the presence of 2-propanol as a hydrogen donor. The product concentration of the reaction in the organic solvent reached 235 mM after 30 h under optimum conditions. Thus, we demonstrated that this novel shuttle vector is useful for developing biocatalysts based on organic solvent-tolerant Kocuria cells. PMID:29230202
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Magnetic storm effects in electric power systems and prediction needs
NASA Technical Reports Server (NTRS)
Albertson, V. D.; Kappenman, J. G.
1979-01-01
Geomagnetic field fluctuations produce spurious currents in electric power systems. These currents enter and exit through points remote from each other. The fundamental period of these currents is on the order of several minutes which is quasi-dc compared to the normal 60 Hz or 50 Hz power system frequency. Nearly all of the power systems problems caused by the geomagnetically induced currents result from the half-cycle saturation of power transformers due to simultaneous ac and dc excitation. The effects produced in power systems are presented, current research activity is discussed, and magnetic storm prediction needs of the power industry are listed.
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Design and analysis of hydraulic ram water pumping system
NASA Astrophysics Data System (ADS)
Hussin, N. S. M.; Gamil, S. A.; Amin, N. A. M.; Safar, M. J. A.; Majid, M. S. A.; Kazim, M. N. F. M.; Nasir, N. F. M.
2017-10-01
The current pumping system (DC water pump) for agriculture is powered by household electricity, therefore, the cost of electricity will be increased due to the higher electricity consumption. In addition, the water needs to be supplied at different height of trees and different places that are far from the water source. The existing DC water pump can pump the water to 1.5 m height but it cost money for electrical source. The hydraulic ram is a mechanical water pump that suitable used for agriculture purpose. It can be a good substitute for DC water pump in agriculture use. The hydraulic ram water pumping system has ability to pump water using gravitational energy or the kinetic energy through flowing source of water. This project aims to analyze and develop the water ram pump in order to meet the desired delivery head up to 3 meter height with less operation cost. The hydraulic ram is designed using CATIA software. Simulation work has been done using ANSYS CFX software to validate the working concept. There are three design were tested in the experiment study. The best design reached target head of 3 m with 15% efficiency and flow rate of 11.82l/min. The results from this study show that the less diameter of pressure chamber and higher supply head will create higher pressure.
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NASA Astrophysics Data System (ADS)
Ali, M. A.; Uddin, M. M.; Khan, M. N. I.; Chowdhury, F.-U.-Z.; Haque, S. M.
2017-02-01
The Sn-substituted Ni-Zn ferrites, (0.0≤x≤0.30), have been synthesized by the standard double sintering technique from the oxide nanopowders of Ni, Zn, Fe and Sn. The structural and electrical properties have been investigated by the X-ray diffraction (XRD), scanning electron microscopy (SEM), DC resistivity and dielectric measurements. From XRD data, the single cubic spinel phase has been confirmed for x≤0.1, whereas for x>0.1 an extra intermediate phase has been detected along with the cubic spinel phase of Ni-Zn ferrite. The grain size is increased due to Sn substitution in Ni-Zn ferrites. DC resistivity as a function of temperature has been measured by two probe method. The semiconducting nature has been found operative in the samples. The DC resistivity was found to decrease whilst the dielectric constant increased with increasing Sn content in Ni-Zn ferrites. The unusual behavior of the dielectric loss factor of the ferrites was explained by the Rezlescu model. The electrical relaxation of the ferrites has been studied in terms of electric modulus formalism and the time for dielectric relaxation was calculated. The contribution of grain resistance has been studied from the Cole-Cole plot. The suitability to use the as prepared samples in the miniaturized memory devices based capacitive components or energy storage principles are confirmed from the values of dielectric constant.
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Król, Żaneta; Marycz, Krzysztof; Kulig, Dominika; Marędziak, Monika; Jarmoluk, Andrzej
2017-01-01
The aim of the study was to investigate the effect of using direct electric current (DC) of 0, 200, and 400 mA for five minutes on the physiochemical properties, cytotoxicity, antibacterial, and antioxidant activity of sodium alginate hydrosols with different sodium chloride concentrations. The pH, oxidation-reduction potential (ORP), electrical conductivity (EC), and available chlorine concentration (ACC) were measured. The effect of sodium alginate hydrosols treated with DC on Staphylococcus aureus, Listeria monocytogenes, Bacillus cereus, Micrococcus luteus, Escherichia coli, Salmonella enteritidis, Yersinia enterocolitica, Pseudomonas fluorescence, and RAW 264.7 and L929 cells was investigated. Subsequently, the antioxidant properties of hydrosols were evaluated by determining the scavenging ability of 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) and ferric reducing antioxidant power (FRAP). The results have shown that after applying 400 mA in hydrosol samples with 0.1% and 0.2% NaCl all tested bacteria were inactivated. The ACC concentration of C400 samples with NaCl was equal to 13.95 and 19.71 mg/L, respectively. The cytotoxicity analysis revealed that optimized electric field conditions and the addition of sodium chloride allow for the avoidance of toxicity effects on normal cells without disturbing the antibacterial effects. Due to the presence of oxidizing substances, the DPPH of variants treated with DC was lower than the DPPH of control samples. PMID:28327520
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Król, Żaneta; Marycz, Krzysztof; Kulig, Dominika; Marędziak, Monika; Jarmoluk, Andrzej
2017-03-22
The aim of the study was to investigate the effect of using direct electric current (DC) of 0, 200, and 400 mA for five minutes on the physiochemical properties, cytotoxicity, antibacterial, and antioxidant activity of sodium alginate hydrosols with different sodium chloride concentrations. The pH, oxidation-reduction potential (ORP), electrical conductivity (EC), and available chlorine concentration (ACC) were measured. The effect of sodium alginate hydrosols treated with DC on Staphylococcus aureus , Listeria monocytogenes , Bacillus cereus , Micrococcus luteus , Escherichia coli , Salmonella enteritidis , Yersinia enterocolitica , Pseudomonas fluorescence , and RAW 264.7 and L929 cells was investigated. Subsequently, the antioxidant properties of hydrosols were evaluated by determining the scavenging ability of 1,1-diphenyl-2-picrylhydrazyl free radical (DPPH) and ferric reducing antioxidant power (FRAP). The results have shown that after applying 400 mA in hydrosol samples with 0.1% and 0.2% NaCl all tested bacteria were inactivated. The ACC concentration of C400 samples with NaCl was equal to 13.95 and 19.71 mg/L, respectively. The cytotoxicity analysis revealed that optimized electric field conditions and the addition of sodium chloride allow for the avoidance of toxicity effects on normal cells without disturbing the antibacterial effects. Due to the presence of oxidizing substances, the DPPH of variants treated with DC was lower than the DPPH of control samples.
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A dual-channel flux-switching permanent magnet motor for hybrid electric vehicles
NASA Astrophysics Data System (ADS)
Hua, Wei; Wu, Zhongze; Cheng, Ming; Wang, Baoan; Zhang, Jianzhong; Zhou, Shigui
2012-04-01
The flux-switching permanent magnet (FSPM) motor is a relatively novel brushless machine having both magnets and concentrated windings in the stator, which exhibits inherently sinusoidal PM flux-linkage, back-EMF waveforms, and high torque capability. However, in the application of hybrid electric vehicles, it is essential to prevent magnets and armature windings moving in radial direction due to the possible vibration during operation, and to ensure fault-tolerant capability. Hence, in this paper based on an original FSPM motor, a dual-channel FSPM (DC-FSPM) motor with modified structure to fix both armature windings and magnets and improved reliability is proposed for a practical 10 kW integral starter/generator (ISG) in hybrid electric vehicles. The influences of different solutions and the end-effect on the static characteristics, are evaluated based on the 2D and 3D finite element analysis, respectively. Finally, both the predicted and experimental results, compared with a prototype DC-FSPM motor and an interior PM motor used in Honda Civic, confirm that the more sinusoidal back-EMF waveform and lower torque ripple can be achieved in the DC-FSPM motor, whereas the torque is smaller under the same coil current.
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NASA Astrophysics Data System (ADS)
Chen, Xiaoyue; Lan, Lei; Lu, Hailiang; Wang, Yu; Wen, Xishan; Du, Xinyu; He, Wangling
2017-10-01
A numerical simulation method of negative direct current (DC) corona discharge based on a plasma chemical model is presented, and a coaxial cylindrical gap is adopted. There were 15 particle species and 61 kinds of collision reactions electrons involved, and 22 kinds of reactions between ions are considered in plasma chemical reactions. Based on this method, continuous Trichel pulses are calculated on about a 100 us timescale, and microcosmic physicochemical process of negative DC corona discharge in three different periods is discussed. The obtained results show that the amplitude of Trichel pulses is between 1-2 mA, and that pulse interval is in the order of 10-5 s. The positive ions produced by avalanche ionization enhanced the electric field near the cathode at the beginning of the pulse, then disappeared from the surface of cathode. The electric field decreases and the pulse ceases to develop. The negative ions produced by attachment slowly move away from the cathode, and the electric field increases gradually until the next pulse begins to develop. The positive and negative ions with the highest density during the corona discharge process are O4+ and O3- , respectively.
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Influence of small DC bias field on the electrical behaviour of Sr- and Mg-doped lanthanum gallate
NASA Astrophysics Data System (ADS)
Raghvendra; Singh, Rajesh Kumar; Singh, Prabhakar
2014-09-01
One of the promising electrolyte materials for solid oxide fuel cells application, Sr- and Mg-doped lanthanum gallate La0.9Sr0.1Ga0.8Mg0.2O3-δ (LSGM), is synthesized by conventional solid state ceramic route. X-ray Rietveld analysis confirms the formation of main orthorhombic phase at room temperature along with a few minor secondary phases. SEM micrograph reveals the grain and grainboundary morphology of the system. Electrical conductivity of the LSGM sample is measured in the temperature range 573-873 K and in the frequency range 20 Hz-1 MHz at a few small DC bias fields (at 0.0, 0.5, 1.0, 1.5 and 2.0 V). The conductivity spectra show power-law behaviour. Electrical conductivity of the sample is found to be weakly dependent on DC bias field. This is attributed to field-dependent bulk and grainboundary conduction processes. In the present system, under investigated bias field range, the possibility of formation of Schottky barrier is ruled out. The concept of grainboundary channel (pathway) modulation on the application of bias field is proposed.
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Cold atmospheric plasma jet in an axial DC electric field
DOE Office of Scientific and Technical Information (OSTI.GOV)
Lin, Li, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu; Keidar, Michael, E-mail: lilin@gwu.edu, E-mail: keidar@gwu.edu
2016-08-15
Cold atmospheric plasma (CAP) jet is currently intensively investigated as a tool for new and potentially transformative cancer treatment modality. However, there are still many unknowns about the jet behavior that requires attention. In this paper, a helium CAP jet is tested in an electrostatic field generated by a copper ring. Using Rayleigh microwave scattering method, some delays of the electron density peaks for different ring potentials are observed. Meanwhile, a similar phenomenon associated with the bullet velocity is found. Chemical species distribution along the jet is analyzed based on the jet optical emission spectra. The spectra indicate that amore » lower ring potential, i.e., lower DC background electric field, can increase the amount of excited N{sub 2}, N{sub 2}{sup +}, He, and O in the region before the ring, but can decrease the amount of excited NO and HO almost along the entire jet. Combining all the results above, we discovered that an extra DC potential mainly affects the temporal plasma jet properties. Also, it is possible to manipulate the chemical compositions of the jet using a ring with certain electric potentials.« less
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Novel bidirectional DC-DC converters based on the three-state switching cell
NASA Astrophysics Data System (ADS)
da Silva Júnior, José Carlos; Robles Balestero, Juan Paulo; Lessa Tofoli, Fernando
2016-05-01
It is well known that there is an increasing demand for bidirectional DC-DC converters for applications that range from renewable energy sources to electric vehicles. Within this context, this work proposes novel DC-DC converter topologies that use the three-state switching cell (3SSC), whose well-known advantages over conventional existing structures are ability to operate at high current levels, while current sharing is maintained by a high frequency transformer; reduction of cost and dimensions of magnetics; improved distribution of losses, with consequent increase of global efficiency and reduction of cost associated to the need of semiconductors with lower current ratings. Three distinct topologies can be derived from the 3SSC: one DC-DC converter with reversible current characteristic able to operate in the first and second quadrants; one DC-DC converter with reversible voltage characteristic able to operate in the first and third quadrants and one DC-DC converter with reversible current and voltage characteristics able to operate in four quadrants. Only the topology with bidirectional current characteristic is analysed in detail in terms of the operating stages in both nonoverlapping and overlapping modes, while the design procedure of the power stage elements is obtained. In order to validate the theoretical assumptions, an experimental prototype is also implemented, so that relevant issues can be properly discussed.
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Stability testing and analysis of a PMAD dc test bed for the Space Station Freedom
NASA Technical Reports Server (NTRS)
Button, Robert M.; Brush, Andrew S.
1992-01-01
The Power Management and Distribution (PMAD) dc Test Bed at the NASA Lewis Research Center is introduced. Its usefulness to the Space Station Freedom Electrical Power (EPS) development and design are discussed in context of verifying system stability. Stability criteria developed by Middlebrook and Cuk are discussed as they apply to constant power dc to dc converters exhibiting negative input impedance at low frequencies. The utility-type Secondary Subsystem is presented and each component is described. The instrumentation used to measure input and output impedance under load is defined. Test results obtained from input and output impedance measurements of test bed components are presented. It is shown that the PMAD dc Test Bed Secondary Subsystem meets the Middlebrook stability criterion for certain loading conditions.
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Stability Testing and Analysis of a PMAD DC Test Bed for the Space Station Freedom
NASA Technical Reports Server (NTRS)
Button, Robert M.; Brush, Andrew S.
1992-01-01
The Power Management and Distribution (PMAD) DC Test Bed at the NASA Lewis Research Center is introduced. Its usefulness to the Space Station Freedom Electrical Power (EPS) development and design are discussed in context of verifying system stability. Stability criteria developed by Middlebrook and Cuk are discussed as they apply to constant power DC to DC converters exhibiting negative input impedance at low frequencies. The utility-type Secondary Subsystem is presented and each component is described. The instrumentation used to measure input and output impedance under load is defined. Test results obtained from input and output impedance measurements of test bed components are presented. It is shown that the PMAD DC Test Bed Secondary Subsystem meets the Middlebrook stability criterion for certain loading conditions.
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Multilevel-Dc-Bus Inverter For Providing Sinusoidal And Pwm Electrical Machine Voltages
Su, Gui-Jia [Knoxville, TN
2005-11-29
A circuit for controlling an ac machine comprises a full bridge network of commutation switches which are connected to supply current for a corresponding voltage phase to the stator windings, a plurality of diodes, each in parallel connection to a respective one of the commutation switches, a plurality of dc source connections providing a multi-level dc bus for the full bridge network of commutation switches to produce sinusoidal voltages or PWM signals, and a controller connected for control of said dc source connections and said full bridge network of commutation switches to output substantially sinusoidal voltages to the stator windings. With the invention, the number of semiconductor switches is reduced to m+3 for a multi-level dc bus having m levels. A method of machine control is also disclosed.
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Reversible vector ratchets for skyrmion systems
DOE Office of Scientific and Technical Information (OSTI.GOV)
Ma, Xiu; Reichhardt, Cynthia Jane Olson; Reichhardt, Charles
In this paper, we show that ac driven skyrmions interacting with an asymmetric substrate provide a realization of a class of ratchet system which we call a vector ratchet that arises due to the effect of the Magnus term on the skyrmion dynamics. In a vector ratchet, the dc motion induced by the ac drive can be described as a vector that can be rotated clockwise or counterclockwise relative to the substrate asymmetry direction. Up to a full 360° rotation is possible for varied ac amplitudes or skyrmion densities. In contrast to overdamped systems, in which ratchet motion is alwaysmore » parallel to the substrate asymmetry direction, vector ratchets allow the ratchet motion to be in any direction relative to the substrate asymmetry. It is also possible to obtain a reversal in the direction of rotation of the vector ratchet, permitting the creation of a reversible vector ratchet. We examine vector ratchets for ac drives applied parallel or perpendicular to the substrate asymmetry direction, and show that reverse ratchet motion can be produced by collective effects. No reversals occur for an isolated skyrmion on an asymmetric substrate. Finally, since a vector ratchet can produce motion in any direction, it could represent a method for controlling skyrmion motion for spintronic applications.« less
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Reversible vector ratchets for skyrmion systems
Ma, Xiu; Reichhardt, Cynthia Jane Olson; Reichhardt, Charles
2017-03-03
In this paper, we show that ac driven skyrmions interacting with an asymmetric substrate provide a realization of a class of ratchet system which we call a vector ratchet that arises due to the effect of the Magnus term on the skyrmion dynamics. In a vector ratchet, the dc motion induced by the ac drive can be described as a vector that can be rotated clockwise or counterclockwise relative to the substrate asymmetry direction. Up to a full 360° rotation is possible for varied ac amplitudes or skyrmion densities. In contrast to overdamped systems, in which ratchet motion is alwaysmore » parallel to the substrate asymmetry direction, vector ratchets allow the ratchet motion to be in any direction relative to the substrate asymmetry. It is also possible to obtain a reversal in the direction of rotation of the vector ratchet, permitting the creation of a reversible vector ratchet. We examine vector ratchets for ac drives applied parallel or perpendicular to the substrate asymmetry direction, and show that reverse ratchet motion can be produced by collective effects. No reversals occur for an isolated skyrmion on an asymmetric substrate. Finally, since a vector ratchet can produce motion in any direction, it could represent a method for controlling skyrmion motion for spintronic applications.« less
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Analysis and Countermeasure Study on DC Bias of Main Transformer in a City
NASA Astrophysics Data System (ADS)
Wang, PengChao; Wang, Hongtao; Song, Xinpu; Gu, Jun; Liu, yong; Wu, weili
2017-07-01
According to the December 2015 Guohua Beijing thermal power transformer DC magnetic bias phenomenon, the monitoring data of 24 hours of direct current is analyzed. We find that the maximum DC current is up to 25 and is about 30s for the trend cycle, on this basis, then, of the geomagnetic storm HVDC and subway operation causes comparison of the mechanism, and make a comprehensive analysis of the thermal power plant’s geographical location, surrounding environment and electrical contact etc.. The results show that the main reason for the DC bias of Guohua thermal power transformer is the operation of the subway, and the change of the DC bias current is periodic. Finally, of Guohua thermal power transformer DC magnetic bias control method is studied, the simulation results show that the method of using neutral point with small resistance or capacitance can effectively inhibit the main transformer neutral point current.
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NASA Astrophysics Data System (ADS)
Anand, V. K.; Hillier, A. D.; Adroja, D. T.; Khalyavin, D. D.; Manuel, P.; Andre, G.; Rols, S.; Koza, M. M.
2018-05-01
The magnetic properties of a pressure induced noncentrosymmetric heavy-fermion superconductor CeIrGe3 have been investigated by muon spin relaxation (μ SR ), powder neutron diffraction (ND), and inelastic neutron scattering (INS) techniques at ambient pressure. For completeness we have also measured the ac magnetic susceptibility χac(T ) , dc magnetic susceptibility χ (T ) , dc isothermal magnetization M (H ) , and heat capacity Cp(T ,H ) down to 2 K. CeIrGe3 is known to exhibit pressure induced superconductivity (Tc≈1.5 K) at a pressure of 20 GPa and antiferromagnetic ordering at 8.7 K, 4.7 K, and 0.7 K at ambient pressure. Our χac(T ) and χ (T ) data show an additional anomaly near 6.2 K which is also captured in Cp(T ) data. From χac(T ) , χ (T ) , and Cp(T ) measurements we infer three antiferromagnetic transitions above 2 K at TN 1=8.5 K, TN 2=6.0 K, and TN 3=4.6 K. Our μ SR study also confirms the presence of three transitions through the observation of one frequency for TN 2
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Experimental prototype of an electric elevator
NASA Astrophysics Data System (ADS)
Gaiceanu, M.; Epure, S.; Ciuta, S.
2016-08-01
The main objective is to achieve an elevator prototype powered by a three-phase voltage system via a bidirectional static power converter ac-ac with regenerating capability. In order to diminish the power size of the electric motor up to 1/3 of rated power, the elevator contains two carriages of the same weight, one serving as the payload, and the other as counterweight. Before proper operation of the static power converter, the capacitor must be charged at rated voltage via a precharge circuit. At the moment of stabilizing the DC voltage at nominal value, the AC-AC power converter can operates in the proper limits. The functions of the control structure are: the load control task, speed and torque controls. System includes transducers for current measuring, voltage sensors and encoder. As reserve power sources the hybrid battery-photovoltaic panels are used. The control voltage is modulated by implementing four types of pulse width modulations: sinusoidal, with reduced commutation, third order harmonic insertion, and the space vector modulation. Therefore, the prototype could operates with an increased efficiency, in spite of the existing ones. The experimental results confirm the well design of the chosen solution. The control solution assures bidirectional power flow control, precharge control, and load control and it is implemented on a digital signal processor. The elevator capacity is between 300-450 kg, and it is driven by using a 1.5 kW three-phase asynchronous machine.
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Reversible Vector Ratchet Effect in Skyrmion Systems
NASA Astrophysics Data System (ADS)
Ma, Xiaoyu; Reichhardt, Charles; Reichhardt, Cynthia
Magnetic skyrmions are topological non-trivial spin textures found in several magnetic materials. Since their motion can be controlled using ultralow current densities, skyrmions are appealing for potential applications in spintronics as information carriers and processing devices. In this work, we studied the collective transport properties of driven skyrmions based on a particle-like model with molecular dynamics (MD) simulation. Our results show that ac driven skyrmions interacting with an asymmetric substrate provide a realization of a new class of ratchet system, which we call a vector ratchet, that arises due to the effect of the Magnus term on the skyrmion dynamics. In a vector ratchet, the dc motion induced by the ac drive can be described as a vector that can be rotated up to 360 degrees relative to the substrate asymmetry direction. This could represent a new method for controlling skyrmion motion for spintronic applications.
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DOE Office of Scientific and Technical Information (OSTI.GOV)
Cristina, S.; Feliziani, M.
1995-11-01
This paper describes a new procedure for the numerical computation of the electric field and current density distributions in a dc electrostatic precipitator in the presence of dust, taking into account the particle-size distribution. Poisson`s and continuity equations are numerically solved by supposing that the coronating conductors satisfy Kaptzov`s assumption on the emitter surfaces. Two iterative numerical procedures, both based on the finite element method (FEM), are implemented for evaluating, respectively, the unknown ionic charge density and the particle charge density distributions. The V-I characteristic and the precipitation efficiencies for the individual particle-size classes, calculated with reference to the pilotmore » precipitator installed by ENEL (Italian Electricity Board) at its Marghera (Venice) coal-fired power station, are found to be very close to those measured experimentally.« less
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Preliminary power train design for a state-of-the-art electric vehicle
NASA Technical Reports Server (NTRS)
Mighdoll, P.; Hahn, W. F.
1978-01-01
Power train designs which can be implemented within the current state-of-the-art were identified by means of a review of existing electric vehicles and suitable off-the-shelf components. The affect of various motor/transmission combinations on vehicle range over the SAE J227a schedule D cycle was evaluated. The selected, state-of-the-art power train employs a dc series wound motor, SCR controller, variable speed transmission, regenerative braking, drum brakes and radial ply tires. Vehicle range over the SAE cycle can be extended by approximately 20% by the further development of separately excited, shunt wound DC motors and electrical controllers. Approaches which could improve overall power train efficiency, such as AC motor systems, are identified. However, future emphasis should remain on batteries, tires and lightweight structures if substantial range improvements are to be achieved.
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Electrically rectified piezoelectric energy harvester excited by rotary magnetic plucking
NASA Astrophysics Data System (ADS)
Shu, Y. C.; Chang, Y. P.; Wang, W. C.
2018-03-01
The paper is focuses on the development of a theoretical framework together with an experimental validation to investigate rotational piezoelectric energy harvesting. The proposed device includes an electrically rectified piezoelectric bimorph mounted on a stationary base with a magnet attached to its free end. Energy is harvested by vibration of beam induced by non-contact rotary magnetic plucking. The DC power frequency response is predicted and found to be in good agreement with experiment. It shows that the harvested DC power is around 1 mW in average with the rotational frequency ranging from 5 Hz to 14 Hz. In addition, the parallel connection of two piezoelectric oscillators with respective electrical rectification is considered. It is observed that the power output of the array is the addition of the response from each individual piezoelectric oscillator.
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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.
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NASA Astrophysics Data System (ADS)
Dobeck, Gerald J.; Cobb, J. Tory
2002-08-01
The high-resolution sonar is one of the principal sensors used by the Navy to detect and classify sea mines in minehunting operations. For such sonar systems, substantial effort has been devoted to the development of automated detection and classification (D/C) algorithms. These have been spurred by several factors including (1) aids for operators to reduce work overload, (2) more optimal use of all available data, and (3) the introduction of unmanned minehunting systems. The environments where sea mines are typically laid (harbor areas, shipping lanes, and the littorals) give rise to many false alarms caused by natural, biologic, and man-made clutter. The objective of the automated D/C algorithms is to eliminate most of these false alarms while still maintaining a very high probability of mine detection and classification (PdPc). In recent years, the benefits of fusing the outputs of multiple D/C algorithms have been studied. We refer to this as Algorithm Fusion. The results have been remarkable, including reliable robustness to new environments. The Quadratic Penalty Function Support Vector Machine (QPFSVM) algorithm to aid in the automated detection and classification of sea mines is introduced in this paper. The QPFSVM algorithm is easy to train, simple to implement, and robust to feature space dimension. Outputs of successive SVM algorithms are cascaded in stages (fused) to improve the Probability of Classification (Pc) and reduce the number of false alarms. Even though our experience has been gained in the area of sea mine detection and classification, the principles described herein are general and can be applied to fusion of any D/C problem (e.g., automated medical diagnosis or automatic target recognition for ballistic missile defense).
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Cockburn, J F; Maddern, G J; Wemyss-Holden, S A
2007-03-01
To examine the effect of applying increasing amounts of direct current (DC) before and during alternating current radiofrequency ablation of porcine liver. Using a Radiotherapeutics RF3000 generator, a 9 V AC/DC transformer and a 16 G plain aluminium tube as an electrode, a control group of 24 porcine hepatic radiofrequency ablation zones was compared with 24 zones created using a bimodal electric tissue ablation (BETA) technique in three pigs. All ablations were terminated when tissue impedance rose to greater than 999 Omega or radiofrequency energy input fell below 5 W on three successive measurements taken at 1 min intervals. BETA ablations were performed in two phases: an initial phase of variable duration DC followed by a second phase during which standard radiofrequency ablation was applied simultaneously with DC. During this second phase, radiofrequency power input was regulated by the feedback circuitry of the RF3000 generator according to changes in tissue impedance. The diameters (mm) of each ablation zone were measured by two observers in two planes perpendicular to the plane of needle insertion. The mean short axis diameter of each ablation zone was subjected to statistical analysis. With increased duration of prior application of DC, there was a progressive increase in the diameter of the ablation zone (p<0.001). This effect increased sharply up to 300 s of pre-treatment after which a further increase in diameter occurred, but at a much lesser rate. A maximum ablation zone diameter of 32 mm was produced (control diameters 10-13 mm). Applying a 9 V DC to porcine liver in vivo, and continuing this DC application during subsequent radiofrequency ablation, results in larger ablation zone diameters compared with radiofrequency ablation alone.
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Nerve lesioning with direct current
NASA Astrophysics Data System (ADS)
Ravid, E. Natalie; Shi Gan, Liu; Todd, Kathryn; Prochazka, Arthur
2011-02-01
Spastic hypertonus (muscle over-activity due to exaggerated stretch reflexes) often develops in people with stroke, cerebral palsy, multiple sclerosis and spinal cord injury. Lesioning of nerves, e.g. with phenol or botulinum toxin is widely performed to reduce spastic hypertonus. We have explored the use of direct electrical current (DC) to lesion peripheral nerves. In a series of animal experiments, DC reduced muscle force by controlled amounts and the reduction could last several months. We conclude that in some cases controlled DC lesioning may provide an effective alternative to the less controllable molecular treatments available today.
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Remote electrical arc suppression by laser filamentation.
Schubert, Elise; Mongin, Denis; Kasparian, Jérôme; Wolf, Jean-Pierre
2015-11-02
We investigate the interaction of narrow plasma channels formed in the filamentation of ultrashort laser pulses, with a DC high voltage. The laser filaments prevent electrical arcs by triggering corona that neutralize the high-voltage electrodes. This phenomenon, that relies on the electric field modulation and free electron release around the filament, opens new prospects to lightning and over-voltage mitigation.
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-05-18
.... South Carolina Electric & Gas Company, Case No. 2-11-cv-1110-CWH (D. S. Car. May 9, 2011). The proposed...'') against South Carolina Electric & Gas Company (``SCE&G''). The claims arise from the release of hazardous..., Washington, DC 20044-7611, and should refer to United States et al. v. South Carolina Electric & Gas Company...
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Federal Register 2010, 2011, 2012, 2013, 2014
2011-06-13
... Michigan and creates an electric field in the water by pulsing low voltage DC current through steel cables... the U.S. Army Corps of Engineers' simultaneous operation of electric barriers IIA and IIB. Under 5 U.S... selected an electric barrier because it is a non-lethal deterrent with a proven history, which does not...
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Mental Models of Elementary and Middle School Students in Analyzing Simple Battery and Bulb Circuits
ERIC Educational Resources Information Center
Jabot, Michael; Henry, David
2007-01-01
Written assessment items were developed to probe students' understanding of a variety of direct current (DC) resistive electric circuit concepts. The items were used to explore the mental models that grade 3-8 students use in explaining the direction of electric current and how electric current is affected by different configurations of simple…
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10 CFR 431.443 - Materials incorporated by reference.
Code of Federal Regulations, 2010 CFR
2010-01-01
... AND INDUSTRIAL EQUIPMENT Small Electric Motors Test Procedures § 431.443 Materials incorporated by... Renewable Energy, Building Technologies Program, Sixth Floor, 950 L'Enfant Plaza, SW., Washington, DC 20024...) IEEE. Institute of Electrical and Electronics Engineers, Inc., 445 Hoes Lane, P.O. Box 1331, Piscataway...
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Application of Filters for High-Altitude Electromagnetic Pulse Protection
1981-04-01
The application of filters for the protection of electrical equipment from electrical transient signals induced by high-altitude electromagnetic ... pulse (HEMP) is discussed, and the application of filters to ac and dc power supplies and analog and digital signal inputs is described. The application
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10 CFR 431.443 - Materials incorporated by reference.
Code of Federal Regulations, 2011 CFR
2011-01-01
... AND INDUSTRIAL EQUIPMENT Small Electric Motors Test Procedures § 431.443 Materials incorporated by... Renewable Energy, Building Technologies Program, Sixth Floor, 950 L'Enfant Plaza, SW., Washington, DC 20024...) IEEE. Institute of Electrical and Electronics Engineers, Inc., 445 Hoes Lane, P.O. Box 1331, Piscataway...
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10 CFR 431.443 - Materials incorporated by reference.
Code of Federal Regulations, 2012 CFR
2012-01-01
... AND INDUSTRIAL EQUIPMENT Small Electric Motors Test Procedures § 431.443 Materials incorporated by... Renewable Energy, Building Technologies Program, Sixth Floor, 950 L'Enfant Plaza, SW., Washington, DC 20024...) IEEE. Institute of Electrical and Electronics Engineers, Inc., 445 Hoes Lane, P.O. Box 1331, Piscataway...
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Power system applications of fiber optic sensors
NASA Technical Reports Server (NTRS)
Johnston, A. R.; Jackson, S. P.; Kirkham, H.; Yeh, C.
1986-01-01
This document is a progress report of work done in 1985 on the Communications and Control for Electric Power Systems Project at the Jet Propulsion Laboratory. These topics are covered: Electric Field Measurement, Fiber Optic Temperature Sensing, and Optical Power transfer. Work was done on the measurement of ac and dc electric fields. A prototype sensor for measuring alternating fields was made using a very simple electroscope approach. An electronic field mill sensor for dc fields was made using a fiber optic readout, so that the entire probe could be operated isolated from ground. There are several instances in which more precise knowledge of the temperature of electrical power apparatus would be useful. This report describes a number of methods whereby the distributed temperature profile can be obtained using a fiber optic sensor. The ability to energize electronics by means of an optical fiber has the advantage that electrical isolation is maintained at low cost. In order to accomplish this, it is necessary to convert the light energy into electrical form by means of photovoltaic cells. JPL has developed an array of PV cells in gallium arsenide specifically for this purpose. This work is described.
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The Ampere and Electrical Standards
Elmquist, Randolph E.; Cage, Marvin E.; Tang, Yi-hua; Jeffery, Anne-Marie; Kinard, Joseph R.; Dziuba, Ronald F.; Oldham, Nile M.; Williams, Edwin R.
2001-01-01
This paper describes some of the major contributions to metrology and physics made by the NIST Electricity Division, which has existed since 1901. It was one of the six original divisions of the National Bureau of Standards. The Electricity Division provides dc and low-frequency calibrations for industrial, scientific, and research organizations, and conducts research on topics related to electrical metrology and fundamental constants. The early work of the Electricity Division staff included the development of precision standards, such as Rosa and Thomas standard resistors and the ac-dc thermal converter. Research contributions helped define the early international system of measurement units and bring about the transition to absolute units based on fundamental principles and physical and dimensional measurements. NIST research has helped to develop and refine electrical standards using the quantum Hall effect and the Josephson effect, which are both based on quantum physics. Four projects covering a number of voltage and impedance measurements are described in detail. Several other areas of current research at NIST are described, including the use of the Internet for international compatibility in metrology, determination of the fine-structure and Planck constants, and construction of the electronic kilogram. PMID:27500018
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NASA Astrophysics Data System (ADS)
Parida, Kalpana; Choudhary, R. N. P.
2017-07-01
CaCu3Ti4O12 (CCTO) was prepared by a chemical reaction method. The pellets prepared from the calcined powder of the material were sintered at 1100 °C. Analysis of x-ray diffraction pattern, recorded on CCTO powder, confirms the phase formation of CCTO. Studies of dielectric (ɛ r, tanδ) and impedance parameters using dielectric and impedance spectroscopy of the compound have provided information about the electrical properties and the dielectric relaxation mechanism of the material. Detailed studies on the variation of electrical conductivity (dc) with temperature show semi-conducting nature of the material. Study of frequency (of applied electric field) dependence of ac conductivity at different temperatures suggests that the compound follows the Jonscher’s power law. Complex impedance spectroscopic analysis suggests that the semicircles formed in the Nyquist plot are connected to the grains, grain boundary and interface effects. An optical energy band gap of ~1.9 eV is obtained from the UV-visible absorbance spectrum. The magnetic data related to magneto-electric (ME) coefficient, measured by varying dc bias magnetic field, have been obtained at room temperature.
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NASA Astrophysics Data System (ADS)
El-Menyawy, E. M.; Zedan, I. T.; Nawar, H. H.
2014-03-01
The electrical and dielectric properties of the synthesized 2-(antipyrin-4-ylhydrazono)-2-(4-nitrophenyl)acetonitrile (AHNA) have been studied. The direct and alternating current (DC and AC) conductivities and complex dielectric constant were investigated in temperature range 303-403 K. The AC conductivity and dielectric properties of AHNA were investigated over frequency range 100 Hz-5 MHz. From DC and AC measurements, electrical conduction is found to be a thermally activated process. The frequency-dependent AC conductivity obeys Jonscher's universal power law in which the frequency exponent decreases with increasing temperature. The correlated barrier hopping (CBH) is the predominant model for describing the charge carrier transport in which the electrical parameters are evaluated. The activation energy is found to decrease with increasing frequency. The behaviors of dielectric and dielectric loss are discussed in terms of a polarization mechanism. The dielectric loss shows frequency power law from which the maximum barrier height is determined as 0.19 eV in terms of the Guintini model.
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Development and testing of a source subsystem for the supporting development PMAD DC test bed
NASA Technical Reports Server (NTRS)
Button, Robert M.
1991-01-01
The supporting Development Power Management and Distribution (PMAD) DC Test Bed is described. Its benefits to the Space Station Freedom Electrical Power System design are discussed along with a short description of how the PMAD DC Test Bed was systematically integrated. The Source Subsystem of the PMAD DC Test Bed consisting of a Sequential Shunt Unit (SSU) and a Battery Charge/Discharge Unit (BCDU) is introduced. The SSU is described in detail and component level test data is presented. Next, the BCDU's operation and design is given along with component level test data. The Source Subsystem is then presented and early data given to demonstrate an effective subsystem design.