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Sample records for active capacitive voltage

  1. Voltage Dependence of Supercapacitor Capacitance

    Szewczyk Arkadiusz

    2016-09-01

    Full Text Available Electronic Double-Layer Capacitors (EDLC, called Supercapacitors (SC, are electronic devices that are capable to store a relatively high amount of energy in a small volume comparing to other types of capacitors. They are composed of an activated carbon layer and electrolyte solution. The charge is stored on electrodes, forming the Helmholtz layer, and in electrolyte. The capacitance of supercapacitor is voltage- dependent. We propose an experimental method, based on monitoring of charging and discharging a supercapacitor, which enables to evaluate the charge in an SC structure as well as the Capacitance-Voltage (C-V dependence. The measurement setup, method and experimental results of charging/discharging commercially available supercapacitors in various voltage and current conditions are presented. The total charge stored in an SC structure is proportional to the square of voltage at SC electrodes while the charge on electrodes increases linearly with the voltage on SC electrodes. The Helmholtz capacitance increases linearly with the voltage bias while a sublinear increase of total capacitance was found. The voltage on SC increases after the discharge of electrodes due to diffusion of charges from the electrolyte to the electrodes. We have found that the recovery voltage value is linearly proportional to the initial bias voltage value.

  2. Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

    Ljusev, P.; Andersen, Michael A.E.

    2005-07-01

    This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify design, increase efficiency and integration level, reduce product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp are presented. (au)

  3. Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify the design, increase effic...... efficiency, reduce the product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp are presented.......This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify the design, increase...

  4. Direct-conversion switching-mode audio power amplifier with active capacitive voltage clamp

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper discusses the advantages and problems when implementing direct energy conversion switching-mode audio power amplifiers. It is shown that the total integration of the power supply and Class D audio power amplifier into one compact direct converter can simplify the design, increase efficiency, reduce the product volume and lower its cost. As an example, the principle of operation and the measurements made on a direct-conversion switching-mode audio power amplifier with active capacit...

  5. Isolated PWM DC-AC SICAM with an active capacitive voltage clamp[Pulse Density Modulated; Pulse Width Modulation

    Ljusev, P.

    2004-03-15

    In this report an isolated PWM DC-AC SICAM with an active capacitive voltage clamp is presented. AC-DC power supply is implemented in its simplest form: diode rectifier followed by a medium-size charge-storage capacitors and possibly with an EMC filter on the mains entrance. Isolation from the AC mains is achieved using a high frequency (HF) transformer, whose voltages are not audio-modulated. The latter simplifies the design and is expected to have many advantages over the approach where the transformer voltages are modulated in regards to the audio signal reference. Input stage is built as a DC-AC inverter (push-pull, half-bridge or a full-bridge) and operated with 50% duty cycle, with all the challenges to avoid transformer saturation and obtain symmetrical operation. On the secondary side the output section is implemented as rectifier+inverter AC-AC stage, i.e. a true bidirectional bridge, which operation is aimed towards amplification of the audio signal. In order to solve the problem with the commutation of the load current, a dead time between the incoming and outgoing bidirectional switch is implemented, while a capacitive voltage clamp is used to keep the induced overvoltage to reasonable levels. The energy stored in the clamping capacitor is not wasted as in the dissipative clamps, but is rather transferred back to the primary side for further processing using an auxiliary isolated single-switch converter, i.e. an active clamping technique is used. (au)

  6. Class D audio amplifiers for high voltage capacitive transducers

    Nielsen, Dennis

    implications of driving the non-linear transducer of the DEAP. 2-level modulated high voltage amplifiers driving the capacitive load of the DEAP transducer are addressed in chapter 4. An amplifier with fourth order output filter and full-state self-oscillating hysteresis based control loop is proposed...... on a silicone film. As a consequence a capacitive transducer emerges, which can be shaped into the loudspeaker membrane itself, rolled up into a transducer driving a membrane or being part of an active suspension system for the membrane. In order to document the full potential of the DEAP transducer, suitable....... Due to the similarities between the electrostatic loudspeaker and the DEAP transducer, the state-of-the-art has a special focus on amplifiers for electrostatic loudspeakers. Amplifiers for other type of capacitive transducers like piezoelectric ones are also considered. Finally the current state...

  7. Composite metal-oxide device has voltage sensitive capacitance

    Mattauch, R. J.; Viola, T. J., Jr.

    1970-01-01

    Device with step function variation of the capacitance is useful for voltage-controlled oscillator circuits and as a voltage-sensitive switch. Simplicity of construction makes the device suitable for large-scale integration, microelectronic circuits.

  8. A Review of High Voltage Drive Amplifiers for Capacitive Actuators

    Huang, Lina; Zhang, Zhe; Andersen, Michael A. E.

    2012-01-01

    This paper gives an overview of the high voltage amplifiers, which are used to drive capacitive actuators. The amplifiers for both piezoelectric and DEAP (dielectric electroactive polymer) actuator are discussed. The suitable topologies for driving capacitive actuators are illustrated in detail......, including linear as well as switched mode amplifiers. In the past much attention has been paid on the driver for piezoelectric actuator. As DEAP is a type of new material, there is not much literature reference for it....

  9. Determination of active doping in highly resistive boron doped silicon nanocrystals embedded in SiO2 by capacitance voltage measurement on inverted metal oxide semiconductor structure

    We investigate the Capacitance-Voltage (CV) measurement to study the electrically active boron doping in Si nanocrystals (ncSi) embedded in SiO2. The ncSi thin films with high resistivity (200–400 Ω cm) can be measured by using an inverted metal oxide semiconductor (MOS) structure (Al/ncSi (B)/SiO2/Si). This device structure eliminates the complications from the effects of lateral current flow and the high sheet resistance in standard lateral MOS structures. The characteristic MOS CV curves observed are consistent with the effective p-type doping. The CV modeling method is presented and used to evaluate the electrically active doping concentration. We find that the highly boron doped ncSi films have electrically active doping of 1018–1019 cm−3 despite their high resistivity. The saturation of doping at about 1.4 × 1019 cm−3 and the low doping efficiency less than 5% are observed and discussed. The calculated effective mobility is in the order of 10−3 cm2/V s, indicating strong impurity/defect scattering effect that hinders carriers transport

  10. Determination of active doping in highly resistive boron doped silicon nanocrystals embedded in SiO{sub 2} by capacitance voltage measurement on inverted metal oxide semiconductor structure

    Zhang, Tian, E-mail: tianz@student.unsw.edu.au; Puthen-Veettil, Binesh; Wu, Lingfeng; Jia, Xuguang; Lin, Ziyun; Yang, Terry Chien-Jen; Conibeer, Gavin; Perez-Wurfl, Ivan [Australian Centre for Advanced Photovoltaics, UNSW Australia, Kensington, New South Wales 2052 (Australia)

    2015-10-21

    We investigate the Capacitance-Voltage (CV) measurement to study the electrically active boron doping in Si nanocrystals (ncSi) embedded in SiO{sub 2}. The ncSi thin films with high resistivity (200–400 Ω cm) can be measured by using an inverted metal oxide semiconductor (MOS) structure (Al/ncSi (B)/SiO{sub 2}/Si). This device structure eliminates the complications from the effects of lateral current flow and the high sheet resistance in standard lateral MOS structures. The characteristic MOS CV curves observed are consistent with the effective p-type doping. The CV modeling method is presented and used to evaluate the electrically active doping concentration. We find that the highly boron doped ncSi films have electrically active doping of 10{sup 18}–10{sup 19 }cm{sup −3} despite their high resistivity. The saturation of doping at about 1.4 × 10{sup 19 }cm{sup −3} and the low doping efficiency less than 5% are observed and discussed. The calculated effective mobility is in the order of 10{sup −3} cm{sup 2}/V s, indicating strong impurity/defect scattering effect that hinders carriers transport.

  11. Low Power/Low Voltage Interface Circuitry for Capacitive Sensors

    Furst, Claus Efdmann

    This thesis focuses mainly on low power/low voltage interface circuits, implemented in CMOS, for capacitive sensors. A brief discussion of demands and possibilities for analog signal processing in the future is presented. Techniques for low power design is presented. This is done by analyzing power...... low power consumption. It is shown that the Sigma-Delta modulator is advantageous when embedded in a feedback loop with a mechanical sensor. Here a micro mechanical capacitive microphone. Feedback and detection circuitry for a capacitive microphone is presented. Practical implementations of low power...

  12. High Voltage Bi-directional Flyback Converter for Capacitive Actuator

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.

    2013-01-01

    in a number of applications. In this paper, the discharging energy efficiency definition is introduced. The proposed converter has been experimentally tested with the film capacitive load and the DEAP actuator, and the experimental results are shown together with the efficiency measurements.......This paper presents a high voltage DC-DC converter topology for bi-directional energy transfer between a low voltage DC source and a high voltage capacitive load. The topology is a bi-directional flyback converter with variable switching frequency control during the charge mode, and constant...... switching frequency control during the discharge mode. The converter is capable of charging the capacitive load from 24 V DC source to 2.5 kV, and discharges it to 0 V. The flyback converter has been analyzed in detail during both charge and discharge modes, by considering all the parasitic elements in the...

  13. MOS Capacitance-Voltage Characteristics:V.Methods to Enhance the Trapping Capacitance

    揭斌斌; 薩支唐

    2012-01-01

    Low-frequency and High-frequency Capacitance-Voltage (C-V) curves of Silicon Metal-Oxide-Semiconductor Capacitors,showing electron and hole trapping at shallow-level dopant and deep-level generationrecombination-trapping impurities,are presented to illustrate the enhancement of the giant trapping capacitances by physical means via device and circuit designs,in contrast to chemical means via impurity characteristics previously reported.Enhancement is realized by masking the electron or/and hole storage capacitances to make the trapping capacitances dominant at the terminals.Device and materials properties used in the computed CV curves are selected to illustrate experimental realizations for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.

  14. Remote gate capacitance-voltage studies for noninvasive surface characterization

    Chang, R. R.; Lile, D. L.; Gann, R.

    1987-01-01

    A measurement technique has been developed which allows noncontact capacitance-voltage measurements to be made using a gate electrode located remote from the semiconductor surface under study. With gate electrodes about 0.5 mm in diameter and gate to semiconductor separations of about 1500 A, it was possible to generate data entirely comparable to that obtained with integrated MIS structures but with the advantage that there was access directly to the free-semiconductor surface. This technique was applied to bulk single-crystal Si and InP samples.

  15. MOS Capacitance-Voltage Characteristics Ⅲ.Trapping Capacitance from 2-Charge-State Impurities

    Jie Binbin; Sah Chihtang

    2011-01-01

    Low-frequency and high-frequency capacitance-voltage curves of Metal-Oxide-Semiconductor Capacitors are presented to illustrate giant electron and hole trapping capacitances at many simultaneously present two-charge-state and one-trapped-carrier,or one-energy-level impurity species.Models described include a donor electron trap and an acceptor hole trap,both donors,both acceptors,both shallow energy levels,both deep,one shallow and one deep,and the identical donor and acceptor.Device and material parameters are selected to simulate chemically and physically realizable capacitors for fundamental trapping parameter characterizations and for electrical and optical signal processing applications.

  16. Active Targets For Capacitive Proximity Sensors

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Lightweight, low-power active targets devised for use with improved capacitive proximity sensors described in "Capacitive Proximity Sensor Has Longer Range" (GSC-13377), and "Capacitive Proximity Sensors With Additional Driven Shields" (GSC-13475). Active targets are short-distance electrostatic beacons; they generate known alternating electro-static fields used for alignment and/or to measure distances.

  17. Digital control of a high-voltage (2.5 kV) bidirectional DC-DC converter for driving a dielectric electro active polymer (DEAP) based capacitive actuator

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.;

    2014-01-01

    the valley switchingtechnique during both charge and discharge processes, withoutthe need to sense signals on the output high-voltage side.Experimental results verifying the bidirectional operation of asingle high voltage flyback converter are presented, using afilm capacitor as the load. Energy......This paper presents a digital control technique toachieve valley switching in a bidirectional flyback converterused to drive a dielectric electro active polymer basedincremental actuator. The incremental actuator consists ofthree electrically isolated, mechanically connected capacitiveactuators....... The incremental actuator requires three highvoltage (~2.5 kV) bidirectional DC-DC converters, toaccomplish the incremental motion by charging anddischarging the capacitive actuators. The bidirectional flybackconverter employs a digital controller to improve efficiencyand charge/discharge speed using...

  18. Capacitance-voltage characteristics of quantum well structures

    Moon, C R; Choe, B D

    1999-01-01

    The characteristics of the apparent carrier distribution (ACD) of quantum well (QW) structures are investigated using the self-consistent simulation and the capacitance-voltage (C-V) profiling techniques. The simulation results on the differential carrier distribution show that the change of position expectation value of two-dimensional electrons determines the full width at half maximum of 100 K ACD peaks when conduction band offset is DELTA E sub c = 160 meV and the QW width t sub w is greater than 120 A. The contribution of Debye averaging effects to the ACD peaks becomes important as t sub w and DELTA E sub c values decrease and the temperature is increased. The influence of Debye averaging effects on ACD peaks appears differently according to the location of each well in multiple QWs. These results indicate that the extraction of QW parameters from the C-V profile should be done with caution.

  19. Bidirectional Flyback Converter with Multiple Series Connected Outputs for High Voltage Capacitive Charge and Discharge Applications

    Thummala, Prasanth; Schneider, Henrik; Zhang, Zhe;

    2015-01-01

    This paper evaluates two different implementations of a bidirectional flyback converter for driving a capacitive electro active actuator, which must be charged and discharged from 0 V to 2.5 kV DC and vice versa, supplied from a 24 V battery. In one implementation, a high voltage MOSFET (4 kV) in...... by lower voltage rating MOSFETs driven by a gate drive transformer. Simulation results to compare the operation of conventional and proposed converters are provided. The advantages of proposed implementation are improved energy efficiency and lower cost. Experimental results with two series connected...

  20. Detection of Telomerase Activity Using Capacitance Measurements

    Kang, Bong Keun; Lee, Ri Mi; Choi, Ahmi; Jung, Hyo-Il; Yoo, Kyung-Hwa

    2007-03-01

    Telomerase activity has been found in about 85% cancer cells, while no activity observed in normal cells, so that telomerase has been proposed as a marker for cancer detection. Here, we describe electrical detection of telomerase activity using capacitance measurements. We have investigated the length dependence of capacitance on DNA solutions and found that the capacitance of DNA solutions were dependent on the DNA length. In addition, upon adding telomerase into the solution of telomeric substrate primer, the capacitance was observed to change as a function of time due to the telomeric elongation. These results suggest that this novel nanosensor may be used for rapid detection of telomerase activity.

  1. Measurement of voltage dependence of capacitance of planar bilayer lipid membrane with a patch clamp amplifier.

    Toyama, S.; Nakamura, A; Toda, F

    1991-01-01

    The voltage dependence of capacitance was measured by using the setup which was almost the same as that for the study of ion channels. The coefficient which represents the voltage dependence of capacitance itself also changes as a function of the duration of voltage application if hexadecane is contained in bilayer lipid membrane (BLM). The method of Alvarez, O., and R. Latorre (1978. Biophys. J. 21:1-17) was extended to treat BLM with hexadecane.

  2. On The Pixel Level Estimation of Pinning Voltage, Pinned Photodiode Capacitance and Transfer Gate Channel Potential

    Goiffon, Vincent; Michelot, Julien; Magnan, Pierre; Estribeau, Magali; Marcelot, Olivier; Cervantes, Paola; Pelamatti, Alice; Martin-Gonthier, Philippe

    2013-01-01

    The pinning voltage extraction method proposed by Tan et al. is analyzed to clarify its benefits and limitations. It is demonstrated that this simple measurement can bring much more useful information than the pinning voltage, such as the pinned photodiode capacitance and the transfer gate channel potential. Objective criteria to compare the pinning voltage on different devices are also discussed.

  3. Capacitance-voltage characteristics of GaAs ion-implanted structures

    Privalov E. N.

    2008-08-01

    Full Text Available A noniterative numerical method is proposed to calculate the barrier capacitance of GaAs ion-implanted structures as a function of the Schottky barrier bias. The features of the low- and high-frequency capacitance-voltage characteristics of these structures which are due to the presence of deep traps are elucidated.

  4. Electrochemical capacitance voltage measurements in highly doped silicon and silicon-germanium alloys

    Sermage, B.; Essa, Z.; Taleb, N.; Quillec, M.; Aubin, J.; Hartmann, J. M.; Veillerot, M.

    2016-04-01

    The electrochemical capacitance voltage technique has been used on highly boron doped SiGe and Si layers. Although the boron concentration is constant over the space charge depth, the 1/C2 versus voltage curves are not linear. They indeed present a negative curvature. This can be explained by the existence of deep acceptors which ionise under a high electric field (large inverse voltage) and not at a low inverse voltage. The measured doping concentration in the electrochemical capacitance voltage increases strongly as the inverse voltage increases. Thanks to a comparison with the boron concentration measured by secondary ions mass spectrometry, we show that the relevant doping concentrations in device layers are obtained for small inverse voltage in agreement with the existence of deep acceptors. At the large inverse voltage, the measured doping can be more than twice larger than the boron concentration measured with a secondary ion mass spectroscopy.

  5. A system for measuring thermal activation energy levels in silicon by thermally stimulated capacitance

    Cockrum, R. H.

    1982-01-01

    One method being used to determine energy level(s) and electrical activity of impurities in silicon is described. The method is called capacitance transient spectroscopy (CTS). It can be classified into three basic categories: the thermally stimulated capacitance method, the voltage-stimulated capacitance method, and the light-stimulated capacitance method; the first two categories are discussed. From the total change in capacitance and the time constant of the capacitance response, emission rates, energy levels, and trap concentrations can be determined. A major advantage of using CTS is its ability to detect the presence of electrically active impurities that are invisible to other techniques, such as Zeeman effect atomic absorption, and the ability to detect more than one electrically active impurity in a sample. Examples of detection of majority and minority carrier traps from gold donor and acceptor centers in silicon using the capacitance transient spectrometer are given to illustrate the method and its sensitivity.

  6. Effect of ion implantation on capacitance-voltage properties of MOS structures

    The effect of rare gas ions, such as Xe+ and Kr+, implanted in the oxide of MOS diodes on the capacitance-voltage properties and triangular voltage stressing has been studied. Results obtained are presented and discussed in terms of interface states and mobility of oxide charges

  7. Nonlinear Parasitic Capacitance Modelling of High Voltage Power MOSFETs in Partial SOI Process

    Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger

    2016-01-01

    : off-state, sub-threshold region, and on-state in the linear region. A high voltage power MOSFET is designed in a partial Silicon on Insulator (SOI) process, with the bulk as a separate terminal. 3D plots and contour plots of the capacitances versus bias voltages for the transistor summarize the...

  8. Active resistance capacitance filter design

    Kerwin, W. J.

    1970-01-01

    Filters, formed by combinations of distributed RC elements with positive-feedback voltage amplifiers, provide transfer functions similar to those the heavier LC filters ordinarily employ. They also provide signal amplification.

  9. Design of a High Voltage Bidirectional DC-DC Converter for Driving Capacitive Incremental Actuators usable in Electric Vehicles (EVs)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.; Maksimovic, Dragan; Sarban, Rahimullah

    2014-01-01

    This paper presents the design of a low input (24 V) and variable high output voltage (0-2.5 kV) bidirectional dc-dc converter for driving a capacitive actuator. The topology is a digitally controlled bidirectional flyback converter with a variable frequency control. The objective is, to design the converter for efficiently charging and discharging the capacitive actuator from 0 V to 2.5 kV and vice versa, respectively. The converter is used to drive a dielectric electro active polymer (DEAP)...

  10. Capacitance of High-Voltage Coaxial Cable in Plasma Immersion Ion Implantation

    2001-01-01

    Plasma immersion ion implantation (PIII) is an excellent technique for the surface modification of complex-shaped components. Owing to pulsed operation mode of the high voltage and large slew rate, the capacitance on the high-voltage coaxial cable can be detrimental to the processand cannot be ignored. In fact, a significant portion of the rise-time/fall-time of the implantation voltage pulse and big initial current can be attributed to the coaxial cable.

  11. A capacitive level shifter for high voltage (2.5kV)

    Andersen, Thomas; Andersen, Michael A. E.; Thomsen, Ole Cornelius;

    2012-01-01

    with focus on low power consumption as well as low capacitive load between the floating half-bridge node and ground (output capacitance). The operation of the level-shifter is tested and verified by measurements on a prototype half-bridge gate driver. Results conclude stabile operation at 2.44kV, 50k......A capacitive level-shifter as a part of a high voltage halfbridge gate driver is resented in this work. The levelshifter utilizes a differential capacitor pair to transfer the information from low side to high side. A thorough evaluation of the critical parts of the level-shifter is presented......Hz with a current consumption of 0.5mA. Operation voltage was limited by test equipment. The output capacitance is 4pF@1.5kV....

  12. Voltage dependence of the differential capacitance of a p+-n junction

    The dependences of the differential capacitance and current of a p+-n junction with a uniformly doped n region on the voltage in the junction region are calculated. The p+-n junction capacitance controls the charge change in the junction region taking into account a change in the electric field of the quasi-neutral n region and a change in its bipolar drift mobility with increasing excess charge-carrier concentration. It is shown that the change in the sign of the p+-n junction capacitance with increasing injection level is caused by a decrease in the bipolar drift mobility as the electron-hole pair concentration in the n region increases. It is shown that the p+-n junction capacitance decreases with increasing reverse voltage and tends to a constant positive value.

  13. Effect of Solar Array Capacitance on the Performance of Switching Shunt Voltage Regulator

    Kumar, Anil R; Suresh, MS; Nagaraju, J

    2006-01-01

    Due to high power demand photovoltaic regulators are being switched at high frequency. The solar cell capacitance increases the ripple voltage of the switching regulators at higher switching frequencies. Increased ripple due to array capacitance is calculated and its effect in limiting the maximum design switching frequency is studied. An experimental switching regulator is designed and used to confirm the theoretical considerations. This study has identified a method of solar cell capacitanc...

  14. Research and Experiments on a Unipolar Capacitive Voltage Sensor.

    Zhou, Qiang; He, Wei; Li, Songnong; Hou, Xingzhe

    2015-01-01

    Voltage sensors are an important part of the electric system. In service, traditional voltage sensors need to directly contact a high-voltage charged body. Sensors involve a large volume, complex insulation structures, and high design costs. Typically an iron core structure is adopted. As a result, ferromagnetic resonance can occur easily during practical application. Moreover, owing to the multilevel capacitor divider, the sensor cannot reflect the changes of measured voltage in time. Based on the electric field coupling principle, this paper designs a new voltage sensor; the unipolar structure design solves many problems of traditional voltage sensors like the great insulation design difficulty and high costs caused by grounding electrodes. A differential signal input structure is adopted for the detection circuit, which effectively restrains the influence of the common-mode interference signal. Through sensor modeling, simulation and calculations, the structural design of the sensor electrode was optimized, miniaturization of the sensor was realized, the voltage division ratio of the sensor was enhanced, and the phase difference of sensor measurement was weakened. The voltage sensor is applied to a single-phase voltage class line of 10 kV for testing. According to the test results, the designed sensor is able to meet the requirements of accurate and real-time measurement for voltage of the charged conductor as well as to provide a new method for electricity larceny prevention and on-line monitoring of the power grid in an electric system. Therefore, it can satisfy the development demands of the smart power grid. PMID:26307992

  15. Voltage-Programming-Based Pixel Circuit to Compensate for Threshold Voltage and Mobility Using Natural Capacitance of Organic Light-Emitting Diode

    Young-Ju Park,; Myoung-Hoon Jung,; Sang-Ho Park,; Ohyun Kim,

    2010-03-01

    A voltage-programming-based pixel circuit with three thin-film transistors (TFTs) and one capacitor (3T1C) is proposed and simulated for active-matrix organic light-emitting diode (AMOLED) displays. Unlike the previously published voltage-programming pixel circuits, which only compensate for threshold voltage (VT) unevenness, this circuit also compensates for mobility (μ) unevenness. OLEDs can be used not only as light-emitting devices but also as capacitors. This circuit uses the natural capacitance of OLEDs to compensate for the mobility unevenness. The Rensselaer Polytechnic Institute (RPI) model of smart simulation program with integrated circuit emphasis (SMART SPICE) is used to simulate the circuit. Moreover, we propose another pixel circuit that consists of three TFTs and two capacitors (3T2C). The additional capacitor allows control of the range of the data voltage of each color.

  16. DC Voltage Control Strategy for CHB-STATCOM during Capacitive-Inductive Load Transition

    Bo Zhao

    2012-11-01

    Full Text Available Fluctuation of DC capacitor voltage of CHC-STATCOM(Cascaded H-Bridge Converter Based STATCOM during capacitive-inductive load transition affects the dynamic response of the equipment and, with combination of other factors like of the switching devices, can degrade the stability of the equipment. This paper illustrates the cause ofthe voltage fluctuation and proposes a novel and practical control strategy to suppress it. A simulation was conducted to testify its effectiveness.

  17. DC Voltage Control Strategy for CHB-STATCOM during Capacitive-Inductive Load Transition

    Bo Zhao; Yong Wang; Weiming Zhao

    2012-01-01

    Fluctuation of DC capacitor voltage of CHC-STATCOM(Cascaded H-Bridge Converter Based STATCOM) during capacitive-inductive load transition affects the dynamic response of the equipment and, with combination of other factors like of the switching devices, can degrade the stability of the equipment. This paper illustrates the cause ofthe voltage fluctuation and proposes a novel and practical control strategy to suppress it. A simulation was conducted to testify its effectiveness.

  18. A method for the extraction of the voltage-dependent quantum capacitance of carbon nanotubes using ab initio simulations

    In this paper, a method to obtain the quantum capacitance of carbon nanotubes (CNTs) using ab initio simulations is presented. As an example of the usage of the proposed method, the quantum capacitance of a metallic (6,6) CNT section is calculated. The quantum capacitance is extracted for various bias voltages applied to metallic CNT interconnects in the range 0-2.5 V, which is the operating voltage range of VLSI circuits. The obtained quantum capacitance values are found to be in good agreement with the experimental values. The average Fermi velocity of electrons dependent on the bias voltage is also obtained and plotted.

  19. Modeling accumulation capacitance-voltage characteristic of MoS2 thin flake transistors

    We report a theoretical investigation on the accumulation capacitance in MoS2 thin flake transistors using a two-valley band structure. To obtain the relevant two-valley band structure parameters, first-principles calculations are performed. Then, the capacitance-voltage characteristic in the accumulation layer is simulated by a self-consistent Poisson–Schrödinger solution. It is found that the occupation of the K valley in the conduction band has a significant contribution to the accumulation capacitance, especially in the strong accumulation layer. More importantly, the calculated results using a two-valley band structure is in good agreement with the published experimental data without any fitting parameters, highlighting that the inclusion of both the Q and K conduction band valley is necessary to understand the accumulation capacitance in the strong accumulation region. (paper)

  20. Capacitance-voltage characteristics and device simulation of bias temperature stressed a-Si:H TFTs

    Tang, Z.; Wie, C. R.

    2010-03-01

    In this paper, the degradation of hydrogenated amorphous silicon thin film transistors under a self-heating stress (SHS) condition is investigated by analyzing the capacitance-voltage characteristics of gate-to-drain capacitance ( Cgd) and gate-to-source capacitance ( Cgs). The very different characteristics of Cgd- V g and Cgs- V g show different stress-induced density of states (DOS) property at the drain side and source side of channel. In a long channel device, the Cgd and Cgs characteristics could be explained by the deep states profile which corresponds to the non-uniform threshold voltage profile induced by the bias temperature stress only. The capacitance-voltage and current-voltage curves, simulated using the ATLAS 2D simulator based on the non-uniform defect states profile, agreed well with the measured data. In a short channel device, the simulation fitting of the Cgd and Cgs data required a non-uniform defect states profile, which is substantially modified from the long channel profile. This was interpreted in terms of a significant contribution of the non-uniform temperature distribution, caused by stress-induced self-heating effect in the short channel device, to the defect states density profile in the channel. A decreased density of conduction band tail states at the source end, corresponding to the increased deep Gaussian states, enabled a good simulation fit in the short channel device.

  1. Selective virtual capacitive impedance loop for harmonics voltage compensation in islanded microgrids

    Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril;

    2013-01-01

    Parallel inverters having LCL output filters cause voltage distortions at the point of common coupling (PCC) in islanded microgrids when non-linear loads are present. A capacitive virtual impedance loop could be used to provide selective harmonic compensation in islanded microgrids, instead of in...

  2. Enhanced Buck–Boost Neutral-Point-Clamped Inverters With Simple Capacitive-Voltage Balancing

    Tan, Kuan Khoon; Gao, Feng; Loh, Poh Chiang;

    2010-01-01

    introduced for extending the inverters’ variation range to include voltageboost operation, but they generally require the inclusion of large passive components or have not yet been optimized in terms of waveform quality. The balancing of their capacitive voltages using a simple technique has also not yet...... been investigated in the context of buck–boost energy conversion, even though relevant techniques for traditional NPC inverters do exist but are generally overburdened by the accompanied switching loss increase and more complex control and hardware circuitries. To address these two topological concerns...... simultaneously, two new buck–boost NPC inverters with simple capacitive-voltage-balancing capability are proposed. Both inverters are demonstrated to exhibit a doubling of voltage gain, with one of them also shown to produce a better output waveform quality. Simulation and experimental results are provided for...

  3. Capacitance Voltage of P3HT:Graphene Nanocomposites Based Bulk-Heterojunction Organic Solar Cells

    Shakina Mohd Shariff, Nur; Mohamad Saad, Puteri Sarah; Rusop Mahmood, Mohamad

    2015-11-01

    After the discovery of conjugated polymer and bulk-heterojunction concept, organic solar cell has gain many interest in the photovoltaic world. The main problem for organic solar cells is that the power conversion efficiency (PCE) is still considered low even though it is much more low cost compared to inorganic solar cell such as Silicon (Si). Therefore, the objective of this research is to investigate the effect of Poly(3-hexylthiophene) (P3HT) thickness and concentration towards the capacitance voltage of the P3HT:Graphene solar cells. A simulation software called SCAPS is used in this research to simulate the effect on the solar cells. SCAPS is specialized for photovoltaic simulation studies. The solar cell's structure will be drawn inside the simulation and the parameters for each layers is inserted. The voltage range will be fixed and the capacitance voltage will be calculated by the software and all the results will be put into one graph. For thickness results, P3HT's layer at a thickness of 100nm has the lowest value of capacitance and clearly shows a peak at 0.86V. Where for the concentration, 1×1016 cm-3 is the only value that clearly shows there is the built-in voltage (Vbi) in the solar cells. Therefore, P3HT's thickness of 100 nm and concentration of 1×1016 cm-3 has the best overall results.

  4. What we talk about when we talk about capacitance measured with the voltage-clamp step method

    Taylor, Adam L.

    2011-01-01

    Capacitance is a fundamental neuronal property. One common way to measure capacitance is to deliver a small voltage-clamp step that is long enough for the clamp current to come to steady state, and then to divide the integrated transient charge by the voltage-clamp step size. In an isopotential neuron, this method is known to measure the total cell capacitance. However, in a cell that is not isopotential, this measures only a fraction of the total capacitance. This has generally been thought ...

  5. Tailored voltage waveform capacitively coupled plasmas in electronegative gases:frequency dependence of asymmetry effects

    Schüngel, E; Korolov, I.; Bruneau, Bastien; Derzsi, A.; Johnson, Erik V.; O'Connell, Deborah; Gans, Timo; Booth, Jean-Paul; Donko, Z.; Schulze, J.

    2016-01-01

    Capacitively coupled radio frequency plasmas operated in an electronegative gas (CF4) and driven by voltage waveforms composed of four consecutive harmonics are investigated for different fundamental driving frequencies using PIC/MCC simulations and an analytical model. As has been observed previously for electropositive gases, the application of peak-shaped waveforms (that are characterized by a strong amplitude asymmetry) results in the development of a DC self-bias due to the electrical as...

  6. Dopant profiling and surface analysis of silicon nanowires using capacitance-voltage measurements.

    Garnett, Erik C; Tseng, Yu-Chih; Khanal, Devesh R; Wu, Junqiao; Bokor, Jeffrey; Yang, Peidong

    2009-05-01

    Silicon nanowires are expected to have applications in transistors, sensors, resonators, solar cells and thermoelectric systems. Understanding the surface properties and dopant distribution will be critical for the fabrication of high-performance devices based on nanowires. At present, determination of the dopant concentration depends on a combination of experimental measurements of the mobility and threshold voltage in a nanowire field-effect transistor, a calculated value for the capacitance, and two assumptions--that the dopant distribution is uniform and that the surface (interface) charge density is known. These assumptions can be tested in planar devices with the capacitance-voltage technique. This technique has also been used to determine the mobility of nanowires, but it has not been used to measure surface properties and dopant distributions, despite their influence on the electronic properties of nanowires. Here, we measure the surface (interface) state density and the radial dopant profile of individual silicon nanowire field-effect transistors with the capacitance-voltage technique. PMID:19421217

  7. Radiation effects on the current-voltage and capacitance-voltage characteristics of advanced p-n junction diodes surrounded by shallow trench isolation

    Poyai, A. E-mail: amporn@imec.be; Simoen, E.; Claeys, C.; Hayama, K.; Kobayashi, K.; Ohyama, H

    2002-01-01

    This paper investigates the impact of 20 MeV proton irradiation on the current-voltage (I-V) and capacitance-voltage (C-V) characteristics of different geometry n{sup +}-p-well junction diodes surrounded by shallow trench isolation and processed in a 0.18 {mu}m CMOS technology. From I-V characteristics, a higher current damage coefficient was found for the bulk than for the peripheral component. The radiation-induced boron de-activation resulted in a lowering of the p-well doping, which has been derived from high-frequency C-V measurements. This was confirmed by deep level transient spectroscopy (DLTS) analysis, revealing the presence of interstitial boron related radiation defects. As will be demonstrated for the bulk leakage-current damage coefficient, the electric field enhanced generation rate of charge carriers and the radiation-induced boron de-activation should be accounted for properly.

  8. Characterization of active CMOS sensors for capacitively coupled pixel detectors

    Hirono, Toko; Gonella, Laura; Janssen, Jens; Hemperek, Tomasz; Huegging, Fabian; Krueger, Hans; Wermes, Norbert [Institute of Physics, University of Bonn (Germany); Peric, Ivan [Institut fuer Prozessdatenverarbeitung und Elektronik, Karlsruher Institut fuer Technologie, Karlsruhe (Germany)

    2015-07-01

    Active CMOS pixel sensor is one of the most attractive candidates for detectors of upcoming particle physics experiments. In contrast to conventional sensors of hybrid detectors, signal processing circuit can be integrated in the active CMOS sensor. The characterization and optimization of the pixel circuit are indispensable to obtain a good performance from the sensors. The prototype chips of the active CMOS sensor were fabricated in the AMS 180nm and L-Foundry 150 nm CMOS processes, respectively a high voltage and high resistivity technology. Both chips have a charge sensitive amplifier and a comparator in each pixel. The chips are designed to be glued to the FEI4 pixel readout chip. The signals from 3 pixels of the prototype chips are capacitively coupled to the FEI4 input pads. We have performed lab tests and test beams to characterize the prototypes. In this presentation, the measurement results of the active CMOS prototype sensors are shown.

  9. Investigation of capacitance voltage characteristics of strained Si/SiGe n-channel MODFET varactor

    Elogail, Y.; Kasper, E.; Gunzer, F.; Shaker, A.; Schulze, J.

    2016-06-01

    This work is concerned with the investigation of Capacitance-Voltage (CV) behavior of n-channel Si/SiGe MODFET varactors. This investigation provides a valuable insight into the high frequency response of the device under test and its dependence on design parameters; especially regarding the modulation layer doping concentration. The heterostructure under consideration is much more complicated than conventional MOS varactor with respect to non-uniform doping, energy band offsets and the pn-junction in series. Subsequently, CV characterization has never been applied to such MODFET varactor structure. Experimental CV measurements have shown a non-monotonic behavior with a transition point minimum and higher saturation levels on both sides, in contradiction to the conventional high frequency MOS characteristics. This behavior was confirmed qualitatively using simulations. Moreover, we explain some fundamental capacitance properties of the structure, which provide already very interesting perceptions of the MODFET varactor operation, modeling and possible applications using the obtained stimulating results.

  10. Attofarad resolution capacitance-voltage measurement of nanometer scale field effect transistors utilizing ambient noise.

    Gokirmak, Ali; Inaltekin, Hazer; Tiwari, Sandip

    2009-08-19

    A high resolution capacitance-voltage (C-V) characterization technique, enabling direct measurement of electronic properties at the nanoscale in devices such as nanowire field effect transistors (FETs) through the use of random fluctuations, is described. The minimum noise level required for achieving sub-aF (10(-18) F) resolution, the leveraging of stochastic resonance, and the effect of higher levels of noise are illustrated through simulations. The non-linear DeltaC(gate-source/drain)-V(gate) response of FETs is utilized to determine the inversion layer capacitance (C(inv)) and carrier mobility. The technique is demonstrated by extracting the carrier concentration and effective electron mobility in a nanoscale Si FET with C(inv) = 60 aF. PMID:19636094

  11. MOS capacitance-voltage characteristics and dielectric properties of ion implanted thermal oxides on silicon

    Structural damage created in thermal oxides on silicon as a result of exposure to energetic ion beams leads to a change of its dielectric and chemical properties. Adverse effects on the oxide-silicon interface in the form of creation of interface states are also to be expected. Ion implanted oxides in MOS structures are studied with the help of MOS capacitance- and conductance-voltage characteristics, reactions of these oxides in etchant solutions, and ellipsometry. Interesting pattern of recovery of these properties is seen when the ion implanted samples are annealed at increasing temperatures. (author)

  12. Use of negative capacitance to provide voltage amplification for low power nanoscale devices.

    Salahuddin, Sayeef; Datta, Supriyo

    2008-02-01

    It is well-known that conventional field effect transistors (FETs) require a change in the channel potential of at least 60 mV at 300 K to effect a change in the current by a factor of 10, and this minimum subthreshold slope S puts a fundamental lower limit on the operating voltage and hence the power dissipation in standard FET-based switches. Here, we suggest that by replacing the standard insulator with a ferroelectric insulator of the right thickness it should be possible to implement a step-up voltage transformer that will amplify the gate voltage thus leading to values of S lower than 60 mV/decade and enabling low voltage/low power operation. The voltage transformer action can be understood intuitively as the result of an effective negative capacitance provided by the ferroelectric capacitor that arises from an internal positive feedback that in principle could be obtained from other microscopic mechanisms as well. Unlike other proposals to reduce S, this involves no change in the basic physics of the FET and thus does not affect its current drive or impose other restrictions. PMID:18052402

  13. Low voltage charge-balanced capacitance-voltage conversion circuit for one-side-electrode-type fluid-based inclination sensor

    Manaf, Asrulnizam Bin Abd; Matsumoto, Yoshinori

    2009-01-01

    A low voltage detection circuit for a capacitance sensor is important for connection to a low voltage digital circuit interface. We studied two different charge-balanced capacitance-voltage ( C- V) conversion circuits configurations; the operational amplifier and the inverter amplifier. Both capacitance detection circuits were designed using 0.35 μm CMOS circuitry technology. Both amplifiers used in the detection circuits were not affected by offset voltage. The current consumption for capacitance detection circuit was reduced from 250 μA at V dd 3.3 V to 38 μA at V dd 1.3 V by switching from an operational amplifier to an inverter amplifier. These circuits were packaged with one-side-electrode-type fluid-based inclination sensors on ceramic substrates. The size of the sensor is ∅ 4.0 mm × 1.0 mm and pure propylene carbonate was used as electrolyte. Changes in temperature did not affect the output voltage of the sensor between -10 °C and 50 °C. This results show that the inverter amplifier used in the detection circuit was not affected by offset voltage and the output voltage V m is depends only on capacitor ratio. The capacitance detection circuit using the inverter amplifier shows a high-sensitivity of about 7 mV/deg over the operational amplifier at V dd 1.3 V. The response time, resolution and minimum moving angle of sensor were 0.7 s, 0.86° and 0.4°, respectively, at V dd 1.3 V for the inverter amplifier type of capacitance detection circuit.

  14. Customized ion flux-energy distribution functions in capacitively coupled plasmas by voltage waveform tailoring

    Schuengel, E; Hartmann, P; Derzsi, A; Korolov, I; Schulze, J

    2016-01-01

    We propose a method to generate a single peak at a distinct energy in the ion flux-energy distribution function (IDF) at the electrode surfaces in capacitively coupled plasmas. The technique is based on the tailoring of the driving voltage waveform, i.e. adjusting the phases and amplitudes of the applied harmonics, to optimize the accumulation of ions created by charge exchange collisions and their subsequent acceleration by the sheath electric field. The position of the peak (i.e. the ion energy) and the flux of the ions within the peak of the IDF can be controlled in a wide domain by tuning the parameters of the applied RF voltage waveform, allowing optimization of various applications where surface reactions are induced at particular ion energies.

  15. Capacitance-voltage investigation of silicon photodiodes damaged by MeV energy light ions

    Complete text of publication follows. Nuclear radiation creates not only deep centers, but in addition influences shallow dopant concentration in semiconductors, as well. At a given temperature the maximum frequency a center can respond to depends on its energy level, therefore the capacitance-voltage (C-V) characteristics of radiation damaged semiconductor diodes should ideally be measured as function of frequency in order to obtain the physical and energy depth distribution of ionized centers [1,2]. In our experiments C-V plots of MeV energy ion irradiated photodiodes were taken at fixed 1 kHz frequency, which is low enough to be sensitive at room temperature to some of the deep levels expected. During, for example, an irradiation with 5.5 MeV α particles the capacitance of a p+nn+ diode increased significantly at low voltages, but showed rather small changes at higher ones. The former turned out to be merely related to a decrease of the built in voltage, corresponding to a lifetime to relaxation type transition of the semiconductor [3]. Rescaling C-V data for this change, the remaining, actual capacitance changes could be interpreted as related to nuclear recoil caused damage located around the end of particle tracks. C-V technique has also been used for follow up investigation of spontaneous self annealing at room temperature of irradiated samples. This is shown here by plotting capacitance data normalized to their virgin values as function of depletion depth for irradiation with 430 keV protons, whose range is about 5 μm. The sensitivity of the method is illustrated for low fluence of 6.5 MeV oxygen, whose range is 5 μm, too, and where the normalization is now made to data taken one week after the irradiation. Acknowledgement This work was supported by the Hungarian Research and Technology Innovation Fund and the Croatian Ministry of Science, Education and Sports within the framework of the Hungarian-Croatian Intergovernmental Science and Technology Co

  16. Correlations of Capacitance-Voltage Hysteresis with Thin-Film CdTe Solar Cell Performance During Accelerated Lifetime Testing

    Albin, D.; del Cueto, J.

    2011-03-01

    In this paper we present the correlation of CdTe solar cell performance with capacitance-voltage hysteresis, defined presently as the difference in capacitance measured at zero-volt bias when collecting such data with different pre-measurement bias conditions. These correlations were obtained on CdTe cells stressed under conditions of 1-sun illumination, open-circuit bias, and an acceleration temperature of approximately 100 degrees C.

  17. Enhanced charge efficiency and reduced energy use in capacitive deionization by increasing the discharge voltage.

    Kim, T; Dykstra, J E; Porada, S; van der Wal, A; Yoon, J; Biesheuvel, P M

    2015-05-15

    Capacitive deionization (CDI) is an electrochemical method for water desalination using porous carbon electrodes. A key parameter in CDI is the charge efficiency, Λ, which is the ratio of salt adsorption over charge in a CDI-cycle. Values for Λ in CDI are typically around 0.5-0.8, significantly less than the theoretical maximum of unity, due to the fact that not only counterions are adsorbed into the pores of the carbon electrodes, but at the same time coions are released. To enhance Λ, ion-exchange membranes (IEMs) can be implemented. With membranes, Λ can be close to unity because the membranes only allow passage for the counterions. Enhancing the value of Λ is advantageous as this implies a lower electrical current and (at a fixed charging voltage) a reduced energy use. We demonstrate how, without the need to include IEMs, the charge efficiency can be increased to values close to the theoretical maximum of unity, by increasing the cell voltage during discharge, with only a small loss of salt adsorption capacity per cycle. In separate constant-current CDI experiments, where after some time the effluent salt concentration reaches a stable value, this value is reached earlier with increased discharge voltage. We compare the experimental results with predictions of porous electrode theory which includes an equilibrium Donnan electrical double layer model for salt adsorption in carbon micropores. Our results highlight the potential of modified operational schemes in CDI to increase charge efficiency and reduce energy use of water desalination. PMID:25278271

  18. Nanoporous activated carbon cloth for capacitive deionization of aqueous solution

    Oh, Han-Jun [Department of Materials Science, Hanseo University, Seosan, 352-820 (Korea, Republic of); Lee, Jong-Ho [Department of Chemistry, Hanseo University, Seosan, 352-820 (Korea, Republic of); Ahn, Hong-Joo [Korea Atomic Energy Research Institute, Daejeon, 305-600 (Korea, Republic of); Jeong, Yongsoo [Korea Institute of Machinery and Materials, Changwon, 641-010 (Korea, Republic of); Kim, Young-Jig [Department of Metallurgical Engineering, Sungkyunkwan University, Suwon, 440-746 (Korea, Republic of); Chi, Choong-Soo [School of Advanced Materials Engineering, Kookmin University, Seoul, 136-702 (Korea, Republic of)]. E-mail: cschi@kookmin.ac.kr

    2006-09-25

    Activated nanostructured-carbon cloths with a high ratio of surface area to volume are used as electrode for capacitive deionization. The electrochemical properties on capacitive deionization for NaCl solution have been investigated to improve efficiency of capacitive deionization properties from aqueous solution, employing chemical surface-modification by etching in alkaline and acidic solution. The removal efficiency of inorganic salts of activated carbon cloths by chemical modification significantly increased. Specially the carbon cloth surface modified in HNO{sub 3} showed an effect of improvement in the CDI efficiency due to not only ion adsorption by an electric double layer, but also electron transfer by Faradaic reaction.

  19. Enhanced Capacitive Characteristics of Activated Carbon by Secondary Activation

    YANG Hui; LU Tian-hong; Yoshio Masaki

    2004-01-01

    The effect of the improvement of commercial activated carbon(AC) on its specific capacitance and high rate capability of double layer(dl) charging/discharging process has been studied. The improvement of AC was carried out via a secondary activation under steam in the presence of catalyst NiCl2, and the suitable condition was found to be a heat treatment at about 875 ℃ for 1 h. Under those conditions, the discharge specific capacitance of the improved AC increases up to 53.67 F/g, showing an increase of about 25% as compared with that of as-received AC. The good rectangular-shaped voltammograms and A.C. impedance spectra prove that the high rate capability of the capacitor made of the improved AC is enhanced significantly. The capacitance resistance(RC) time constant of the capacitor containing the improved AC is 1.74 s, which is much lower than that of the one containing as-received AC(an RC value of 4. 73 s). It is noted that both kinds of AC samples show a similar specific surface area and pore size distribution, but some changes have taken place in the carbon surface groups, especially a decrease in the concentration of surface carbonyl groups after the improvement, which have been verified by means of X-photoelectron spectroscopy. Accordingly, it is suggested that the decrease in the concentration of surface carbonyl groups for the improved AC is beneficial to the organic electrolyte ion penetrating into the pores, thus leading to the increase in both the specific capacitance and high rate capability of the supercapacitor.

  20. Design of a High Voltage Bidirectional DC-DC Converter for Driving Capacitive Incremental Actuators usable in Electric Vehicles (EVs)

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.;

    2014-01-01

    converter for efficiently charging and discharging the capacitive actuator from 0 V to 2.5 kV and vice versa, respectively. The converter is used to drive a dielectric electro active polymer (DEAP) based capacitive incremental actuator, which has the potential to be used in automotive (e.g., EVs), space and...

  1. Electron heating and control of ion properties in capacitive discharges driven by customized voltage waveforms

    We investigate the electron heating dynamics in capacitively coupled radio frequency plasmas driven by customized voltage waveforms and study the effects of modifying this waveform and the secondary electron emission coefficient of the electrodes on the spatio-temporal ionization dynamics by particle-in-cell simulations. We demonstrate that changes in the electron heating dynamics induced by voltage waveform tailoring strongly affect the dc self-bias, the ion flux, Γi, and the mean ion energy, 〈Ei〉, at the electrodes. The driving voltage waveform is customized by adding N consecutive harmonics (N ⩽ 4) of 13.56 MHz with specific harmonics' amplitudes and phases. The total voltage amplitude is kept constant, while modifying the number of harmonics and their phases. In an argon plasma, we find a dc self-bias, η, to be generated via the electrical asymmetry effect for N ⩾ 2. η can be controlled by adjusting the harmonics' phases and is enhanced by adding more consecutive harmonics. At a low pressure of 3 Pa, the discharge is operated in the α-mode and 〈Ei〉 can be controlled by adjusting the phases at constant Γi. The ion flux can be increased by adding more harmonics due to the enhanced electron-sheath heating. 〈Ei〉 does not remain constant as a function of N at both electrodes due to a change in η. These findings verify previous results of Lafleur et al. At a high pressure of 100 Pa and using a high secondary electron emission coefficient of γ = 0.4, the discharge is operated in the γ-mode and mode transitions are induced by changing the driving voltage waveform. Due to these mode transitions and the specific ionization dynamics in the γ-mode, Γi is no longer constant as a function of the harmonics' phases and decreases with increasing N. (paper)

  2. Capacitance-voltage characteristics of Si and Ge nanomembrane based flexible metal-oxide-semiconductor devices under bending conditions

    Cho, Minkyu; Seo, Jung-Hun; Park, Dong-Wook; Zhou, Weidong; Ma, Zhenqiang

    2016-06-01

    Metal-oxide-semiconductor (MOS) device is the basic building block for field effect transistors (FET). The majority of thin-film transistors (TFTs) are FETs. When MOSFET are mechanically bent, the MOS structure will be inevitably subject to mechanical strain. In this paper, flexible MOS devices using single crystalline Silicon (Si) and Germanium (Ge) nanomembranes (NM) with SiO2, SiO, and Al2O3 dielectric layers are fabricated on a plastic substrate. The relationships between semiconductor nanomembranes and various oxide materials are carefully investigated under tensile/compressive strain. The flatband voltage, threshold voltage, and effective charge density in various MOS combinations revealed that Si NM-SiO2 configuration shows the best interface charge behavior, while Ge NM-Al2O3 shows the worst. This investigation of flexible MOS devices can help us understand the impact of charges in the active region of the flexible TFTs and capacitance changes under the tensile/compressive strains on the change in electrical characteristics in flexible NM based TFTs.

  3. The electrochemical capacitance-voltage characterization of InP based p-i-n structures

    Wang, Li-wei; Lu, Yi-dan; Xu, Jin-tong; Li, Xiang-yang

    2013-09-01

    Electrochemical Capacitance-Voltage (EC-V) profiling is currently one of the most often used methods for majority carrier concentration depth profiling of semiconductors. The experiments of EC-V profiling on InP based structures were conducted by Wafer Profiler CVP21, and there are two problems in the experiments of InP based p-i-n structures : a)the experimental results of EC-V profiling of i layer were not in line with the theoretically data after the EC-V profiling of p layer, which can be measured within the error range; b) The measurements of etching depth were not very accurate. In this paper, we made comparative experiments on InP based n-i-n structures, and find out a method to deal with the first problem: firstly etch p layer before EC-V profiling, so we can gain a relatively accurate result of EC-V profiling of i layer. Besides, use back contacts instead of front contacts to do the EC-V profiling according to the instruction book of the Wafer Profiler CVP21. Then the author tried to infer the reason that results in the first problem theoretically. Meanwhile we can calibrate the etching depth through Profile-system and Scanning Probe Microscope (SPM). And there are two possible reasons which result in the second problem: the defects of the semiconductors and the electrolyte we used to etch the semiconductors.

  4. Trap profiling at nanocavity bands in silicon wafers by means of capacitance-voltage measurements

    Auriac, N

    2002-01-01

    Nanocavities are formed by He sup + -and H sup + -ion implantation in silicon single crystals, at the projected range R sub p , after post-implantation annealing. The present paper deals with the characterization of deep trap levels associated with such defects. P-type silicon single crystals were implanted using He sup + -and H sup + -ion beams, at an energy of 250 keV and to a dose of 3 x 10 sup 1 sup 6 cm sup - sup 2. Capacitance-voltage (C-V) profiling and deep-level transient spectroscopy (DLTS) techniques were used to determine the density profile and the energy levels of deep traps in the gap. In implanted and post-annealed samples a quasi-triangular profile of the space charge is revealed around R sub p by C-V profiling, and the space charge density reaches 10 sup 1 sup 6 cm sup - sup 3. DLTS suggests that trap levels are located at 0.4 eV above the valence band, with a maximum density around 10 sup 1 sup 5 cm sup - sup 3 at R sub p. The sign and distribution of the space charge for depletion in He su...

  5. Laterally Inhomogeneous Barrier Analysis Using Capacitance-Voltage Characteristics of Identically Fabricated Schottky Diodes

    Çavdar, Şükrü; Tuğluoğlu, Nihat; Akgül, Kübra Bengin; Koralay, Haluk

    2016-08-01

    Au Schottky contacts (50 dots) on n-Si (100) were fabricated by thermal evaporation under the same conditions. The mean of the electrical parameters of the diodes were investigated by means of capacitance-voltage ( C- V) measurements at 1 MHz. Even if the diodes were all equally fabricated, there was a diode-to-diode change. The values of barrier height (ΦB) were determined from the C -2- V characteristics, which ranged from 0.812 eV to 0.837 eV. The Gaussian fit of the barrier height distributions gave a mean of barrier height value of 0.822 eV and a standard value of 0.005 eV. Furthermore, the mean values of other parameters such as the carrier donor concentration ( N D), the diffusion potential at zero bias ( V 0), the Fermi level ( E F), the image force lowering (ΔΦb) and the space charge layer width ( W D) were investigated and determined to be 1.311 × 1015 cm-3, 0.575 V, 0.257 eV, 1.363 × 10-2 eV, and 7.573 × 10-5 cm, respectively.

  6. Capacitively coupled hydrogen plasmas sustained by tailored voltage waveforms: excitation dynamics and ion flux asymmetry

    Bruneau, B.; Diomede, P.; Economou, D. J.; Longo, S.; Gans, T.; O’Connell, D.; Greb, A.; Johnson, E.; Booth, J.-P.

    2016-08-01

    Parallel plate capacitively coupled plasmas in hydrogen at relatively high pressure (~1 Torr) are excited with tailored voltage waveforms containing up to five frequencies. Predictions of a hybrid model combining a particle-in-cell simulation with Monte Carlo collisions and a fluid model are compared to phase resolved optical emission spectroscopy measurements, yielding information on the dynamics of the excitation rate in these discharges. When the discharge is excited with amplitude asymmetric waveforms, the discharge becomes electrically asymmetric, with different ion energies at each of the two electrodes. Unexpectedly, large differences in the \\text{H}2+ fluxes to each of the two electrodes are caused by the different \\text{H}3+ energies. When the discharge is excited with slope asymmetric waveforms, only weak electrical asymmetry of the discharge is observed. In this case, electron power absorption due to fast sheath expansion at one electrode is balanced by electron power absorption at the opposite electrode due to a strong electric field reversal.

  7. Carrier concentration profiling in magnetic GaMnSb/GaSb investigated by electrochemistry capacitance-voltage profiler

    2002-01-01

    Depth profiles of carrier concentrations in Ga- MnSb/GaSb are investigated by electrochemistry capacitance-voltage profiler and electrolyte of Tiron. The carrier concentration in GaMnSb/GaSb measured by this method is coincident with the results of Hall and X-ray diffraction measurements. It is indicated that most of the Mn atoms in GaMnSb take the site of Ga, play a role of acceptors, and provide shallow acceptor level(s).

  8. Isolating the effect of pore size distribution on electrochemical double-layer capacitance using activated fluid coke

    Zuliani, Jocelyn E.; Tong, Shitang; Kirk, Donald W.; Jia, Charles Q.

    2015-12-01

    Electrochemical double-layer capacitors (EDLCs) use physical ion adsorption in the capacitive electrical double layer of high specific surface area (SSA) materials to store electrical energy. Previous work shows that the SSA-normalized capacitance increases when pore diameters are less than 1 nm. However, there still remains uncertainty about the charge storage mechanism since the enhanced SSA-normalized capacitance is not observed in all microporous materials. In previous studies, the total specific surface area and the chemical composition of the electrode materials were not controlled. The current work is the first reported study that systematically compares the performance of activated carbon prepared from the same raw material, with similar chemical composition and specific surface area, but different pore size distributions. Preparing samples with similar SSAs, but different pores sizes is not straightforward since increasing pore diameters results in decreasing the SSA. This study observes that the microporous activated carbon has a higher SSA-normalized capacitance, 14.1 μF cm-2, compared to the mesoporous material, 12.4 μF cm-2. However, this enhanced SSA-normalized capacitance is only observed above a threshold operating voltage. Therefore, it can be concluded that a minimum applied voltage is required to induce ion adsorption in these sub-nanometer micropores, which increases the capacitance.

  9. Characterization of Highly Efficient CdTe Thin Film Solar Cells by the Capacitance-Voltage Profiling Technique

    Okamoto, Tamotsu; Yamada, Akira; Konagai, Makoto

    2000-05-01

    The electrical properties of highly efficient CdTe thin film solar cells prepared by close-spaced sublimation (CSS) were investigated by capacitance-voltage (C-V) measurement. According to the dependence of the cell performance on the substrate temperature in the CSS process, the open-circuit voltage (Voc) increased with increasing the substrate temperature below 630°C@. The carrier concentration profiles revealed that the net acceptor concentration exponentially increased from the CdS/CdTe interface to the rear and that the acceptor concentration increased with increasing substrate temperature. This result suggests that Voc is improved as a result of the increase in the acceptor concentration.

  10. Efficiency of Capacitively Loaded Converters

    Andersen, Thomas; Huang, Lina; Andersen, Michael A. E.;

    2012-01-01

    introduced as a definition of efficiency. The calculated and measured efficiency curves for charging DEAP actuator, polypropylene film capacitor and X7R MLCC are provided and compared. The attention has to be paid for the voltage dependent capacitive load, like X7R MLCC, when evaluating the charging......This paper explores the characteristic of capacitance versus voltage for dielectric electro active polymer (DEAP) actuator, 2kV polypropylene film capacitor as well as 3kV X7R multi layer ceramic capacitor (MLCC) at the beginning. An energy efficiency for capacitively loaded converters is...... polypropylene film capacitor can be the equivalent capacitive load. Because of the voltage dependent characteristic, X7R MLCC cannot be used to replace the DEAP actuator. However, this type of capacitor can be used to substitute the capacitive actuator with voltage dependent property at the development phase....

  11. Tailored voltage waveform capacitively coupled plasmas in electronegative gases: frequency dependence of asymmetry effects

    Schüngel, E.; Korolov, I.; Bruneau, B.; Derzsi, A.; Johnson, E.; O’Connell, D.; Gans, T.; Booth, J.-P.; Donkó, Z.; Schulze, J.

    2016-07-01

    Capacitively coupled radio frequency plasmas operated in an electronegative gas (CF4) and driven by voltage waveforms composed of four consecutive harmonics are investigated for different fundamental driving frequencies using PIC/MCC simulations and an analytical model. As has been observed previously for electropositive gases, the application of peak-shaped waveforms (that are characterized by a strong amplitude asymmetry) results in the development of a DC self-bias due to the electrical asymmetry effect (EAE), which increases the energy of ions arriving at the powered electrode. In contrast to the electropositive case (Korolov et al 2012 J. Phys. D: Appl. Phys. 45 465202) the absolute value of the DC self-bias is found to increase as the fundamental frequency is reduced in this electronegative discharge, providing an increased range over which the DC self-bias can be controlled. The analytical model reveals that this increased DC self-bias is caused by changes in the spatial profile and the mean value of the net charge density in the grounded electrode sheath. The spatio-temporally resolved simulation data show that as the frequency is reduced the grounded electrode sheath region becomes electronegative. The presence of negative ions in this sheath leads to very different dynamics of the power absorption of electrons, which in turn enhances the local electronegativity and plasma density via ionization and attachment processes. The ion flux to the grounded electrode (where the ion energy is lowest) can be up to twice that to the powered electrode. At the same time, while the mean ion energies at both electrodes are quite different, their ratio remains approximately constant for all base frequencies studied here.

  12. 特高压电容式电压互感器介损和电容测量方法分析%Testing analysis of dielectric loss and capacitance of ultra-high voltage capacitive voltage transformer

    苏陈云; 黄震

    2012-01-01

    电容式电压互感器(CVT)的电容量和介质损耗角的测量是检验设备绝缘性能的一项重要试验,特高压1 000kV CVT因其具有自身独有的特性,其试验方法也具有特殊性.比较系统地介绍了特高压变电站中2种不同结构的500 kV CVT电容量和介损的测量方法.主要针对1 000kV电容式电压互感器结构特殊性采用了一种新的试验方法,通过现场试验,测试结果符合特高压交流试验示范工程电气设备交接试验标准要求,证明采用外高压、内标准、正接法测量CVT中压臂电容C2是可行的.%The measuring of dielectric loss and capacitance of capacitive voltage transformer is important for equipment insulation level. The test on ultra-high voltage 1 000 kV capacitive voltage transformer is different than other transformers. The method to measure two different structural 500 kV CVT is systematically introduced. Furthermore, a new test method of 1 000 kV CVT is proposed according to particular feature of 1 000 kV CVT. The method use external standard capacitor, internal high voltage and positive connection to measure C2 capacitor of CVT. The test results meet standards of UHV AC pilot project hand-over regulations according to the on-site test, which proves the validity of proposed method.

  13. On the scaling of rf and dc self-bias voltages with pressure in electronegative capacitively coupled plasmas

    Higher gas densities and lower diffusion losses at higher operating pressures typically lead to increased charged species densities (and hence flux) for a constant power deposition in capacitively coupled plasmas (CCP). As a result, one would expect that the bias radio-frequency (rf) voltage required to deposit a given power in a CCP reactor decreases with increasing operating pressure. These observations may not hold true in multiple frequency CCPs, commonly used for dielectric etching in microelectronics fabrication, due to nonlinear interactions between the rf sources. Wafer-based measurements of the rf and self-generated direct current (dc) bias voltages in a dual-frequency capacitively coupled electronegative plasma were made, which indicate that the rf and dc voltages vary nonmonotonically with pressure. These experimental results are presented in this paper and a computational plasma model is used to explain the experimental observations for varying 60 MHz and 13 MHz powers in the Ar/CF4/CHF3 plasma over a pressure range of 25 to 400 mTorr. The authors found that while the ion density increases with pressure, the increase is most dominant near the electrode with the high frequency source (60 MHz). The rf and dc bias voltages are ultimately influenced by both charged species density magnitudes and spatial profiles.

  14. Molecular Insights into Carbon Nanotube Supercapacitors: Capacitance Independent of Voltage and Temperature

    Feng, Guang [Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Li, Song [Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Atchison, Jennifer S. [Leibniz Inst. for New Materials (INM), Saarbrücken (Germany); Presser, Volker [Leibniz Inst. for New Materials (INM), Saarbrücken (Germany); Cummings, Peter T. [Vanderbilt Univ., Nashville, TN (United States). Dept. of Chemical and Biomolecular Engineering; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Center for Nanophase Materials Science

    2013-04-12

    Molecular dynamics (MD) simulations of supercapacitors with single-walled carbon nanotube (SWCNT) electrodes in room-temperature ionic liquids were performed to investigate the influences of the applied electrical potential, the radius/curvature of SWCNTs, and temperature on their capacitive behavior. It is found that (1) SWCNTs-based supercapacitors exhibit a near-flat capacitance–potential curve, (2) the capacitance increases as the tube radius decreases, and (3) the capacitance depends little on the temperature. We report the first MD study showing the influence of the electrode curvature on the capacitance–potential curve and negligible dependence of temperature on capacitance of tubular electrode. The latter is in good agreement with recent experimental findings and is attributed to the similarity of the electrical double layer (EDL) microstructure with temperature varying from 260 to 400 K. The electrode curvature effect is explained by the dominance of charge overscreening and increased ion density per unit area of electrode surface.

  15. MOS Capacitance-Voltage Characteristics Ⅱ.Sensitivity of Electronic Trapping at Dopant Impurity from Parameter Variations

    Jie Binbin; Sah Chihtang

    2011-01-01

    Low-frequency and high-frequency Capacitance-Voltage(C V)curves of Metal OxideSemiconductor Capacitors(MOSC),including electron and hole trapping at the dopant donor and acceptor impurities,are presented to illustrate giant trapping capacitances,from > 0.01Cox to > 10Cox.Five device and materials parameters are varied for fundamental trapping parameter characterization,and electrical and optical signal processing applications.Parameters include spatially constant concentration of the dopant-donor-impurity electron trap,NDD,the ground state electron trapping energy level depth measured from the conduction band edge,EC-ED,the degeneracy of the trapped electron at the ground state,gD,the device temperature,T,and the gate oxide thickness,xox.

  16. Characterization of electrical and mechanical activities of rabbit uterus associated with the presence of capacitated and non-capacitated spermatozoa

    J.F. Lazcano-Reyes; Montiel, J.L.; Medrano, A.

    2013-01-01

    To investigate the effects capacitated spermatozoa may exert upon motility of the rabbit uterus, both contractility and electrical activity (frequency and intensity) were measured in 3 distinctive uterine segments of anaesthetized does: horn (UH), uterotubal junction (UTJ) and tube (UT) after 1) natural mating, 2) infusion of either seminal plasma or PBS, 3) infusion of either capacitated or non-capacitated spermatozoa. Basal values were: 17.1, 15.7, 16.4 g (contractility, P>0.05); 3.5, 3.5, ...

  17. Superior capacitive performance of active carbons derived from Enteromorpha prolifera

    Highlights: • An ocean biomass, Entromorphra prolifera, has been processed into supercapacitor electrodes. • KOH activation can prepare hierarchical porous carbon. • The as-prepared carbons have high capacitance with good rate capability. • This work provided an approach to value-added products from an ocean biomass. - Abstract: Enteromorpha prolifera (E.prolifera), an ocean biomass, was used as raw materials to prepare active carbons by a two-step strategy (pre-carbonization followed by chemical activation). The as-prepared active carbons have been characterized by a variety of means such as N2 adsorption, field emission scanning electron microscope, transmission electron microscope, Raman spectroscopy. The results showed that the carbons have large surface area and developed porosity with micro-meso hierarchical pore texture. As evidenced by electrochemical measurements, the specific capacitance of the carbons can reach up to 296 F g−1. More importantly, the carbons can maintain a high capacitance of up to 152 F g−1 at a very high current density of 30 A g−1, highlighting the promise of the carbons for high power applications

  18. Capacitance-voltage spectroscopy of self-organized InAs/GaAs quantum dots embedded in a pn diode

    Wetzler, R.; Wacker, A.; Schoell, E. [Technische Univ. Berlin (Germany). Inst. fuer Theoretische Physik; Kapteyn, C.M.A.; Heitz, R.; Bimberg, D. [Technische Univ. Berlin (Germany). Inst. fuer Festkoerperphysik

    2001-03-01

    We investigate the energy levels and their inhomogeneous broadening of self-organized quantum dots (QDs) embedded in a pn diode by means of capacitance-voltage (C-V) profiling. Our simulations of the C-V characteristics are based on the self-consistent solution of the Poisson equation and the drift-diffusion equations. Good quantitative agreement between predictions of the model and the low-frequency C-V characteristics is obtained for different temperatures. The comparison with experimental C-V data allows us to determine the energy levels of single QD states and their broadening. (orig.)

  19. New ways of measuring the pull-in voltage and transient behavior of parallel-plate capacitive MEMS transducers

    In this paper we introduce two new ways of measuring the pull-in voltage and the transient behavior of parallel-plate capacitive microelectromechanical systems (MEMS) transducers. The advantages in the measurement speed and resolution of the so-called fast MEMS test will be discussed. Also an enhanced method, the time-resolved dynamic measurement, will be shown. With the second method, we can visualize the integral displacement of a membrane while measuring the voltage drop of a high-frequency signal over a shunt resistor/capacitor. With a more advanced charge amplifier circuit, also a force-free resonance measurement of the membrane and electrode is possible in one step. All this offers a robust and cheap option for tracing moving structures without the need of an optical line of sight. (paper)

  20. The influence of the relative phase between the driving voltages on electron heating in asymmetric dual frequency capacitive discharges

    The influence of the relative phase between the driving voltages on electron heating in asymmetric phase-locked dual frequency capacitively coupled radio frequency plasmas operated at 2 and 14 MHz is investigated. The basis of the analysis is a nonlinear global model with the option to implement a relative phase between the two driving voltages. In recent publications it has been reported that nonlinear electron resonance heating can drastically enhance the power dissipation to electrons at moments of sheath collapse due to the self-excitation of nonlinear plasma series resonance (PSR) oscillations of the radio frequency current. This work shows that depending on the relative phase of the driving voltages, the total number and exact moments of sheath collapse can be influenced. In the case of two consecutive sheath collapses a substantial increase in dissipated power compared with the known increase due to a single PSR excitation event per period is observed. Phase resolved optical emission spectroscopy (PROES) provides access to the excitation dynamics in front of the driven electrode. Via PROES the propagation of beam-like energetic electrons immediately after the sheath collapse is observed. In this work we demonstrate that there is a close relation between moments of sheath collapse, and thus excitation of the PSR, and beam-like electron propagation. A comparison of simulation results to experiments in a single and dual frequency discharge shows good agreement. In particular the observed influence of the relative phase on the dynamics of a dual frequency discharge is described by means of the presented model. Additionally, the analysis demonstrates that the observed gain in dissipation is not accompanied by an increase in the electrode's dc-bias voltage which directly addresses the issue of separate control of ion flux and ion energy in dual frequency capacitively coupled radio frequency plasmas.

  1. Simulation of cold plasma in a chamber under high- and low-frequency voltage conditions for a capacitively coupled plasma

    Hao Daoxin; Cheng Jia; Ji Linhong; Sun Yuchun

    2012-01-01

    The characteristics of cold plasma,especially for a dual-frequency capacitively coupled plasma (CCP),play an important role for plasma enhanced chemical vapor deposition,which stimulates further studies using different methods.In this paper,a 2D fluid model was constructed for N2 gas plasma simulations with CFD-ACE+,a commercial multi-physical software package.First,the distributions of electric potential (Epot),electron number density (Ne),N number density (N) and electron temperature (Te) are described under the condition of high frequency (HF),13.56 MHz,HF voltage,300 V,and low-frequency (LF) voltage,0 V,particularly in the sheath.Based on this,the influence of HF on Ne is further discussed under different HF voltages of 200 V,300 V,400 V,separately,along with the influence of LF,0.3 MHz,and various LF voltages of 500 V,600 V,700 V.The results show that sheaths of about 3 mm are formed near the two electrodes,in which Epot and Te vary extensively with time and space,while in the plasma bulk Epot changes synchronously with an electric potential of about 70 V and Te varies only in a small range.N is also modulated by the radio frequency,but the relative change in N is small.Ne varies only in the sheath,while in the bulk it is steady at different time steps.So,by comparing Ne in the plasma bulk at the steady state,we can see that Ne will increase when HF voltage increases.Yet,Ne will slightly decrease with the increase of LF voltage.At the same time,the homogeneity will change in both x and y directions.So both HF and LF voltages should be carefully considered in order to obtain a high-density,homogeneous plasma.

  2. Asymmetric Electrodes Constructed with PAN-Based Activated Carbon Fiber in Capacitive Deionization

    Mingzhe Li

    2014-01-01

    Full Text Available Capacitive deionization (CDI method has drawn much attention for its low energy consumption, low pollution, and convenient manipulation. Activated carbon fibers (ACFs possess high adsorption ability and can be used as CDI electrode material. Herein, two kinds of PAN-based ACFs with different specific surface area (SSA were used for the CDI electrodes. The CDI performance was investigated; especially asymmetric electrodes’ effect was evaluated. The results demonstrated that PAN-based ACFs showed a high electrosorption rate (complete electrosorption in less than half an hour and moderate electrosorption capacity (up to 0.2 mmol/g. CDI experiments with asymmetric electrodes displayed a variation in electrosorption capacity between forward voltage and reverse voltage. It can be attributed to the electrical double layer (EDL overlap effect and inner pore potential; thus the ions with smaller hydrated ionic radius can be adsorbed more easily.

  3. Coordinated Voltage Control of Active Distribution Network

    Xie Jiang

    2016-01-01

    Full Text Available This paper presents a centralized coordinated voltage control method for active distribution network to solve off-limit problem of voltage after incorporation of distributed generation (DG. The proposed method consists of two parts, it coordinated primal-dual interior point method-based voltage regulation schemes of DG reactive powers and capacitors with centralized on-load tap changer (OLTC controlling method which utilizes system’s maximum and minimum voltages, to improve the qualified rate of voltage and reduce the operation numbers of OLTC. The proposed coordination has considered the cost of capacitors. The method is tested using a radial edited IEEE-33 nodes distribution network which is modelled using MATLAB.

  4. DEVELOPMENT OF NEW CHARTS OF CAPACITANCE-RESISTANCE DEFENSE OF HIGH-VOLTAGE CAPACITORS OF POWERFUL CAPACITY STORES OF ENERGY FROM EMERGENCY CURRENTS

    M.I. Baranov

    2015-12-01

    Full Text Available Purpose. Development of new charts of capacitance-resistance defense of high-voltage capacitors of powerful capacity stores of energy (CSE from emergency large impulsive currents (LIC at the electric hasp of one of condensers of such CSE on the stage of their charge or discharge. Methodology. Electrophysics bases of the technique of high-voltage and large pulsed currents, and also scientific and technical bases of planning of devices of high-voltage impulse technique. Results. Two new charts of capacitance-resistance defense of high-voltage impulsive capacitors are offered for powerful CSE of one- and multimodule execution from emergency LIC, being based on the use of high-voltage permanent graphite-ceramic resistors of type of TVO-60 a face value from 24 to 100 Ohm, set on the high-voltage conclusions of all of condensers of CSE. One of the developed capacitance-resistance charts of defense of condensers for powerful one-module CSE passed practical approbation. Originality. It is shown that application of the developed charts of capacitance-resistance defense of high-voltage condensers of powerful CSE is provided by frequent limitation of amplitude of emergency LIC, flowing through broken through an electric discharge condenser of CSE on the stage of his charge or discharge. Such limitation emergency LIC is prevented by explosion destruction of the damaged condenser of high-voltage CSE. Practical value. The use of the developed charts of capacitance-resistance defense of high-voltage capacitors from emergency LIC allows substantially to promote functional safety of powerful CSE of one- and multi-module execution and provide the safe terms of labour for a scientific and technical personnel, attendant similar CSE.

  5. Cooperative Control with Virtual Selective Harmonic Capacitance for Harmonic Voltage Compensation in Islanded MicroGrids

    Micallef, A.; Apap, M.; Spitero-Stanies, C.;

    2012-01-01

    This paper focuses on the islanded operation of microgrids. In this mode of operation, the microsources are required to cooperate autonomously to regulate the local grid voltage and frequency. Droop control is typically used to achieve this autonomous voltage and frequency regulation. Inverters h...

  6. Experimental investigations of electron heating dynamics and ion energy distributions in capacitive discharges driven by customized voltage waveforms

    Capacitively coupled radio frequency plasmas driven by customized voltage waveforms provide enhanced opportunities to control process-relevant energy distributions of different particle species. Here, we present an experimental investigation of the spatio-temporal electron heating dynamics probed by Phase-Resolved Optical Emission Spectroscopy (PROES) in an argon discharge driven by up to three consecutive harmonics of 13.56 MHz with individually adjustable harmonics' amplitudes and phases. PROES and voltage measurements are performed at fixed total voltage amplitudes as a function of the number of driving harmonics, their relative phases, and pressure to study the effects of changing the applied voltage waveform on the heating dynamics in collisionless and collisional regimes. Additionally, the ion energy distribution function (IEDF) is measured at low pressure. In this collisionless regime, the discharge is operated in the α-mode. The velocity of energetic electron beams generated by the expanding sheaths is found to be affected by the number of driving harmonics and their relative phases. This is understood based on the sheath dynamics obtained from a model that determines sheath voltage waveforms. The formation of the measured IEDFs is understood and found to be directly affected by the observed changes in the electron heating dynamics. It is demonstrated that the mean ion energy can be controlled by adjusting the harmonics' phases. In the collisional regime at higher pressures changing the number of harmonics and their phases at fixed voltage is found to induce heating mode transitions from the α- to the γ-mode. Finally, a method to use PROES as a non-invasive diagnostic to monitor and detect changes of the ion flux to the electrodes is developed

  7. Experimental investigations of electron heating dynamics and ion energy distributions in capacitive discharges driven by customized voltage waveforms

    Berger, Birk [Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Institute for Theoretical Electrical Engineering, Ruhr University Bochum, D-44780 Bochum (Germany); Brandt, Steven; Franek, James; Schüngel, Edmund; Koepke, Mark; Schulze, Julian [Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315 (United States); Mussenbrock, Thomas [Institute for Theoretical Electrical Engineering, Ruhr University Bochum, D-44780 Bochum (Germany)

    2015-12-14

    Capacitively coupled radio frequency plasmas driven by customized voltage waveforms provide enhanced opportunities to control process-relevant energy distributions of different particle species. Here, we present an experimental investigation of the spatio-temporal electron heating dynamics probed by Phase-Resolved Optical Emission Spectroscopy (PROES) in an argon discharge driven by up to three consecutive harmonics of 13.56 MHz with individually adjustable harmonics' amplitudes and phases. PROES and voltage measurements are performed at fixed total voltage amplitudes as a function of the number of driving harmonics, their relative phases, and pressure to study the effects of changing the applied voltage waveform on the heating dynamics in collisionless and collisional regimes. Additionally, the ion energy distribution function (IEDF) is measured at low pressure. In this collisionless regime, the discharge is operated in the α-mode. The velocity of energetic electron beams generated by the expanding sheaths is found to be affected by the number of driving harmonics and their relative phases. This is understood based on the sheath dynamics obtained from a model that determines sheath voltage waveforms. The formation of the measured IEDFs is understood and found to be directly affected by the observed changes in the electron heating dynamics. It is demonstrated that the mean ion energy can be controlled by adjusting the harmonics' phases. In the collisional regime at higher pressures changing the number of harmonics and their phases at fixed voltage is found to induce heating mode transitions from the α- to the γ-mode. Finally, a method to use PROES as a non-invasive diagnostic to monitor and detect changes of the ion flux to the electrodes is developed.

  8. 电容分压型电子电压互感器的特性研究%Characteristics of electronic voltage transformers based on capacitive voltage divider

    杨玲君; 周冬旭; 徐志超

    2012-01-01

    The transfer function model of EVT(Electronic Voltage Transformer based on capacitive voltage divider) is analyzed and deduced. Its frequency characteristics and the transient characteristics of its trapped charge are analyzed. The transient mathematical model of trapped charge is deduced and the parameters which have influences on frequency characteristics and transient characteristics are analyzed mathematically. Simulative results show that,the capacitors of voltage divider and the parameters of integrator have great effects on the frequency characteristics and transient characteristics of EVT. Reducing the integral capacitor or integral feedback resistor may reduce its bandwidth. Reducing the sampling resistor or high-voltage capacitor may increase its bandwidth. Reducing the low-voltage capacitor or sampling resistor may shorten the transient process caused by the trapped charge and then reduce the transient error.%分析和建立电容分压型电子电压互感器(EVT)的传递函数模型,重点分析了EVT的频率特性和滞留电荷的暂态特性,建立了滞留电荷暂态数学模型,对影响频率特性和暂态特性的参数进行了数学分析.仿真分析表明EVT的频率特性和暂态响应过程与高、低压电容和积分器参数有关.可知:减小积分电容或减小积分反馈电阻时可减小频带宽度;减小采样电阻或高压臂电容可增加频带宽度;减小低压电容或采样电阻可缩短滞留电荷造成的暂态过程,减小暂态误差.

  9. Analytical Charge Voltage Model in MOS Inversion Layer Based on Space Charge Capacitance

    2000-01-01

    The concept of Space Charge Capacitance (SCC) is proposed and used to make a novel analytical charge model of quantized inversion layer in MOS structures. Based on SCC,continuous expressions of surface potential and inversion layer carrier density are derived.Quantum mechanical effects on both inversion layer carrier density and surface potential are extensively included. The accuracy of the model is verified by the numerical solution to Schrodinger and Poisson equation and the model is demonstrated,too.

  10. Gate-to-drain capacitance verifying the continuous-wave green laser crystallization n-TFT trapped charges distribution under dc voltage stress

    Hsieh, Zhen-Ying; Wang, Mu-Chun; Chen, Shuang-Yuan; Chen, Chih; Huang, Heng-Sheng

    2009-12-01

    In this work, a metrology was proposed to realize the distribution of fixed oxide trapped charges and grain boundary trapped states. The (continuous-wave green laser crystallization) n-channel thin-film transistors (TFTs) were forced by dc voltage stress, VG=VD. The gate-to-drain capacitance, CGD-VG, with varying frequency of applied small signal was developed. To probe the distribution of these defects, the difference (initial capacitance values minus stressed capacitance values) of CGD-VG with different frequencies was precisely studied.

  11. Digital Control of a High Voltage (2.5 kV) Bidirectional Flyback DC-DC Converter for Driving a Capacitive Incremental Actuator

    Thummala, Prasanth; Maksimovic, Dragan; Zhang, Zhe;

    2016-01-01

    (0-2.5 kV) bidirectional dc-dc flyback converter for driving a capacitive incremental actuator. The incremental actuator consists of three electrically isolated, mechanically connected capacitive actuators. It requires three high voltage (2-2.5 kV) bidirectional dc-dc converters, to accomplish the...... incremental motion by charging and discharging the capacitive actuators. The bidirectional flyback converter employs a digital controller to improve efficiency and charge/discharge speed using the valley switching technique during both charge and discharge processes, without the need to sense signals on the...... output high-voltage (HV) side. Experimental results verifying the bidirectional operation of a high voltage flyback converter are presented, using a 3 kV polypropylene film capacitor as the load. The energy loss distributions of the converter when 4 kV and 4.5 kV HV MOSFETs are used on HV side are...

  12. Peculiarities of the capacitance-voltage characteristic of a photoelectric solar energy convertor based on a silicon p- n junction with a porous silicon antireflection coating

    Tregulov, V. V.

    2014-09-01

    Experimental results on the high-frequency capacitance-voltage characteristic of a photoelectric solar energy converter based on the n +- p junction with a thin porous silicon film on the frontal surface are considered. It is shown that the capacitance-voltage characteristic is determined by the surface metal-insulator-semiconductor (MIS) structure formed as a result of growing of a porous silicon layer by electrochemical anode etching. The effective thickness of the insulator layer of the MIS structure, the impurity concentration in its semiconductor region, and the density of surface states are determined.

  13. Activated carbon nanofiber webs made by electrospinning for capacitive deionization

    Activated carbon fiber (ACF) webs with a non-woven multi-scale texture were fabricated from polyacrylonitrile (PAN), and their electrosorption performance in capacitive deionization for desalination was investigated. PAN nanofibers were prepared by electrospinning, followed by oxidative stabilization and activation with carbon dioxide at 750–900 °C, resulting in the ACF webs that were characterized by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and nitrogen adsorption. The results show that the as-made ACFs have a specific surface area of 335–712 m2/g and an average nanofiber diameter of 285–800 nm, which can be tuned by varying the activation temperature. With the ACF webs as an electrode, an electrosorption capacity as high as 4.64 mg/g was achieved on a batch-type electrosorptive setup operated at 1.6 V. The ACF webs made by electrospinning are of potential as an excellent electrode material for capacitive deionization for desalination.

  14. Layout Capacitive Coupling and Structure Impacts on Integrated High Voltage Power MOSFETs

    Fan, Lin; Knott, Arnold; Jørgensen, Ivan Harald Holger

    2016-01-01

    -to-layer coupling and the comparison of the layout impacts have not been well established. This paper presents modeling of parasitic mutual coupling to analyze the parasitic capacitance directly coupled between two on-chip metal wires. The accurate 3D field solver analysis for the comparable dimensions shows that...... the layer-to-layer coupling can contribute higher impacts than the well-known side-by-side coupling. Four layout structures are then proposed and implemented in a 0.18 µm partial SOI process for 100 V integrated power MOSFETs with a die area 2.31 mm2. The post-layout comparison using an industrial 2D...

  15. Investigation of fluoride removal from low-salinity groundwater by single-pass constant-voltage capacitive deionization.

    Tang, Wangwang; Kovalsky, Peter; Cao, Baichuan; Waite, T David

    2016-08-01

    Capacitive deionization (CDI) is attracting increasing attention as an emerging technology for the facile removal of ionic species from water. In this work, the feasibility of fluoride removal from low-salinity groundwaters by single-pass constant-voltage CDI was investigated and a model developed to describe the dynamic fluoride electrosorption behavior. Effects of operating parameters including charging voltage and pump flow rate as well as impact of fluoride and chloride feed concentrations on the effluent fluoride concentration and equilibrium fluoride adsorption capacity were studied and the obtained data used to validate the model. Using the validated model, the effects of various design parameters, including arrangement of multiple CDI cells, on fluoride removal were assessed. Single-pass constant-voltage CDI was found to be effective in removing fluoride from low-salinity groundwaters but, as expected, removal efficiency was compromised in waters of high salinity. The relatively simple electrosorption model developed here provided a satisfactory description of both fluoride removal and current evolution and would appear to be a useful tool for prediction of CDI performance over a range of operating conditions, cell arrangements and feed water compositions though scope for model improvement exists. PMID:27151285

  16. Effect of driving voltages in dual capacitively coupled radio frequency plasma: A study by nonlinear global model

    On the basis of nonlinear global model, a dual frequency capacitively coupled radio frequency plasma driven by 13.56 MHz and 27.12 MHz has been studied to investigate the influences of driving voltages on the generation of dc self-bias and plasma heating. Fluid equations for the ions inside the plasma sheath have been considered to determine the voltage-charge relations of the plasma sheath. Geometrically symmetric as well as asymmetric cases with finite geometrical asymmetry of 1.2 (ratio of electrodes area) have been considered to make the study more reasonable to experiment. The electrical asymmetry effect (EAE) and finite geometrical asymmetry is found to work differently in controlling the dc self-bias. The amount of EAE has been primarily controlled by the phase angle between the two consecutive harmonics waveforms. The incorporation of the finite geometrical asymmetry in the calculations shift the dc self-bias towards negative polarity direction while increasing the amount of EAE is found to increase the dc self-bias in either direction. For phase angle between the two waveforms ϕ = 0 and ϕ = π/2, the amount of EAE increases significantly with increasing the low frequency voltage, whereas no such increase in the amount of EAE is found with increasing high frequency voltage. In contrast to the geometrically symmetric case, where the variation of the dc self-bias with driving voltages for phase angle ϕ = 0 and π/2 are just opposite in polarity, the variation for the geometrically asymmetric case is different for ϕ = 0 and π/2. In asymmetric case, for ϕ = 0, the dc self-bias increases towards the negative direction with increasing both the low and high frequency voltages, but for the ϕ = π/2, the dc-self bias is increased towards positive direction with increasing low frequency voltage while dc self-bias increases towards negative direction with increasing high frequency voltage

  17. Experimental and modeling study of the capacitance-voltage characteristics of metal-insulator-semiconductor capacitor based on pentacene/parylene

    Wondmagegn, Wudyalew T.

    2011-04-01

    The capacitance-voltage (C-V) characteristics of metal-insulator- semiconductor (MIS) capacitors consisting of pentacene as an organic semiconductor and parylene as the dielectric have been investigated by experimental, analytical, and numerical analysis. The device simulation was performed using two-dimensional drift-diffusion methods taking into account the Poole-Frenkel field-dependent mobility. Pentacene bulk defect states and fixed charge density at the semiconductor/insulator interface were incorporated into the simulation. The analysis examined pentacene/parylene interface characteristics for various parylene thicknesses. For each thickness, the corresponding flat band voltage extracted from the C-V plot of the MIS structure was more negative than - 2.4 V. From the flat band voltage the existence of a significant mismatch between the work functions of the gate electrode and pentacene active material has been identified. Experimental and simulation results suggest the existence of interface charge density on the order of 3 × 1011 q/cm2 at the insulator/semiconductor interface. The frequency dispersion characteristics of the device are also presented and discussed. © 2011 Elsevier B.V.

  18. Enhanced capacitive properties of commercial activated carbon by re-activation in molten carbonates

    Lu, Beihu; Xiao, Zuoan; Zhu, Hua; Xiao, Wei; Wu, Wenlong; Wang, Dihua

    2015-12-01

    Simple, affordable and green methods to improve capacitive properties of commercial activated carbon (AC) are intriguing since ACs possess a predominant role in the commercial supercapacitor market. Herein, we report a green reactivation of commercial ACs by soaking ACs in molten Na2CO3-K2CO3 (equal in mass ratios) at 850 °C combining the merits of both physical and chemical activation strategies. The mechanism of molten carbonate treatment and structure-capacitive activity correlations of the ACs are rationalized. Characterizations show that the molten carbonate treatment increases the electrical conductivity of AC without compromising its porosity and wettability of electrolytes. Electrochemical tests show the treated AC exhibited higher specific capacitance, enhanced high-rate capability and excellent cycle performance, promising its practical application in supercapacitors. The present study confirms that the molten carbonate reactivation is a green and effective method to enhance capacitive properties of ACs.

  19. Capacitance-voltage characteristics of (Al/Ti)/Al2O3/n-GaN MIS structures

    The capacitance-voltage characteristics of (Al/Ti)/Al2O3/n-GaN metal—insulator-semiconductor (MIS) structures are measured and analyzed. n-Type GaN films are grown on sapphire (0001) substrates by the metal-organic chemical vapor deposition method. An aluminum-oxide layer with a thickness of 60 nm is deposited onto the surface of GaN by the method of atomic-layer deposition from the gas phase. Metallic contacts are deposited by the electron-beam evaporation of titanium and aluminum in vacuum. According to the measurement results, the breakdown-field strength of the oxide, its dielectric constant, and the integrated electron density of states at the oxide-semiconductor interface are 5 × 106 V/cm, 7.5, and 3 × 1012 cm−2, respectively

  20. Temperature-Dependent Current-Voltage (I-V) and Capacitance-Voltage (C-V) Characteristics of Ni/Cu/n-InP Schottky Barrier Diodes

    Munikrishana Reddy, Y.; Nagaraj, M. K.; Siva Pratap Reddy, M.; Lee, Jung-Hee; Rajagopal Reddy, V.

    2013-04-01

    The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of Ni/Cu/n-InP Schottky barrier diodes are studied over a wide temperature range, from 210 K to 420 K. The I-V characteristics display anomalous thermal behavior. The apparent barrier height decays, and the ideality factor grows at low temperatures, and the series resistances resulting from Cheung's and Norde's procedures are markedly temperature dependent. The nonlinearity of the Richardson plot and the strong temperature dependence of the Schottky-barrier parameters indicate that the interface is spatially inhomogeneous. Plots of the zero-bias barrier height as a function of 1/(2kT) points to a Gaussian distribution of barrier heights with 0.90 eV mean height and 0.014 eV standard deviation. When this distribution is accounted for, a Richardson of 6.5 A/(cm K)2 results, relatively close to the 9.4/(cm K)2 predicted by theory. We conclude that, combined with a Gaussian distribution of barrier heights, the thermionic-emission mechanism explains the temperature-dependent I-V and C-V characteristics of the studied Schottky-barrier diodes.

  1. Electron power absorption dynamics in capacitive radio frequency discharges driven by tailored voltage waveforms in CF4

    Brandt, S.; Berger, B.; Schüngel, E.; Korolov, I.; Derzsi, A.; Bruneau, B.; Johnson, E.; Lafleur, T.; O’Connell, D.; Koepke, M.; Gans, T.; Booth, J.-P.; Donkó, Z.; Schulze, J.

    2016-08-01

    The power absorption dynamics of electrons and the electrical asymmetry effect in capacitive radio-frequency plasmas operated in CF4 and driven by tailored voltage waveforms are investigated experimentally in combination with kinetic simulations. The driving voltage waveforms are generated as a superposition of multiple consecutive harmonics of the fundamental frequency of 13.56 MHz. Peaks/valleys and sawtooth waveforms are used to study the effects of amplitude and slope asymmetries of the driving voltage waveform on the electron dynamics and the generation of a DC self-bias in an electronegative plasma at different pressures. Compared to electropositive discharges, we observe strongly different effects and unique power absorption dynamics. At high pressures and high electronegativities, the discharge is found to operate in the drift-ambipolar (DA) heating mode. A dominant excitation/ionization maximum is observed during sheath collapse at the edge of the sheath which collapses fastest. High negative-ion densities are observed inside this sheath region, while electrons are confined for part of the RF period in a potential well formed by the ambipolar electric field at this sheath edge and the collapsed (floating potential) sheath at the electrode. For specific driving voltage waveforms, the plasma becomes divided spatially into two different halves of strongly different electronegativity. This asymmetry can be reversed electrically by inverting the driving waveform. For sawtooth waveforms, the discharge asymmetry and the sign of the DC self-bias are found to reverse as the pressure is increased, due to a transition of the electron heating mode from the α-mode to the DA-mode. These effects are interpreted with the aid of the simulation results.

  2. Low Capacitive Inductors for Fast Switching Devices in Active Power Factor Correction Applications

    Hernandez Botella, Juan Carlos; Petersen, Lars Press; Andersen, Michael A. E.

    2014-01-01

    This paper examines different winding strategies for reduced capacitance inductors in active power factor correction circuits (PFC). The effect of the parasitic capacitance is analyzed from an electro magnetic compatibility (EMI) and efficiency point of views. The purpose of this work is to...... investigate different winding approaches and identify suitable solutions for high switching frequency/high speed transition PFC designs. A low parasitic capacitance PCB based inductor design is proposed to address the challenges imposed by high switching frequency PFC Boost converters....

  3. Development of a versatile readout and test system and characterization of a capacitively coupled active pixel sensor

    Janssen, Jens; Gonella, Laura; Hemperek, Tomasz; Hirono, Toko; Huegging, Fabian; Krueger, Hans; Wermes, Norbert [Institute of Physics, University of Bonn, Bonn (Germany); Peric, Ivan [Karlsruher Institut fuer Technologie, Karlsruhe (Germany); Collaboration: ATLAS-Collaboration

    2015-07-01

    With the availability of high voltage and high resistivity CMOS processes, active pixel sensors are becoming increasingly interesting for radiation detection in high energy physics experiments. Although the pixel signal-to-noise ratio and the sensor radiation tolerance were improved, active pixel sensors cannot yet compete with state-of-the-art hybrid pixel detector in a high radiation environment. Hence, active pixel sensors are possible candidates for the outer tracking detector in HEP experiments where production cost plays a role. The investigation of numerous prototyping steps and different technologies is still ongoing and requires a versatile test and readout system, which will be presented in this talk. A capacitively coupled active pixel sensor fabricated in AMS 180 nm high voltage CMOS process is investigated. The sensor is designed to be glued to existing front-end pixel readout chips. Results from the characterization are presented in this talk.

  4. Development of a versatile readout and test system and characterization of a capacitively coupled active pixel sensor

    With the availability of high voltage and high resistivity CMOS processes, active pixel sensors are becoming increasingly interesting for radiation detection in high energy physics experiments. Although the pixel signal-to-noise ratio and the sensor radiation tolerance were improved, active pixel sensors cannot yet compete with state-of-the-art hybrid pixel detector in a high radiation environment. Hence, active pixel sensors are possible candidates for the outer tracking detector in HEP experiments where production cost plays a role. The investigation of numerous prototyping steps and different technologies is still ongoing and requires a versatile test and readout system, which will be presented in this talk. A capacitively coupled active pixel sensor fabricated in AMS 180 nm high voltage CMOS process is investigated. The sensor is designed to be glued to existing front-end pixel readout chips. Results from the characterization are presented in this talk.

  5. Actively Biased p-Channel MOSFET Studied with Scanning Capacitance Microscopy

    DE WOLF,P.; DODD,PAUL E.; HETHERINGTON,DALE L.; NAKAKURA,CRAIG Y.; SHANEYFELT,MARTY R.

    1999-09-22

    Scanning capacitance microscopy (SCM) was used to study the cross section of an operating p-channel MOSFET. We discuss the novel test structure design and the modifications to the SCM hardware that enabled us to perform SCM while applying dc bias voltages to operate the device. The results are compared with device simulations performed with DAVINCI.

  6. Temperature dependence of current-and capacitance-voltage characteristics of an Au/4H-SiC Schottky diode

    Gülnahar, Murat

    2014-12-01

    In this study, the current-voltage (I-V) and capacitance-voltage (C-V) measurements of an Au/4H-SiC Schottky diode are characterized as a function of the temperature in 50-300 K temperature range. The experimental parameters such as ideality factor and apparent barrier height presents to be strongly temperature dependent, that is, the ideality factor increases and the apparent barrier height decreases with decreasing temperature, whereas the barrier height values increase with the temperature for C-V data. Likewise, the Richardson plot deviates at low temperatures. These anomaly behaviors observed for Au/4H-SiC are attributed to Schottky barrier inhomogeneities. The barrier anomaly which relates to interface of Au/4H-SiC is also confirmed by the C-V measurements versus the frequency measured in 300 K and it is interpreted by both Tung's lateral inhomogeneity model and multi-Gaussian distribution approach. The values of the weighting coefficients, standard deviations and mean barrier height are calculated for each distribution region of Au/4H-SiC using the multi-Gaussian distribution approach. In addition, the total effective area of the patches NAe is obtained at separate temperatures and as a result, it is expressed that the low barrier regions influence meaningfully to the current transport at the junction. The homogeneous barrier height value is calculated from the correlation between the ideality factor and barrier height and it is noted that the values of standard deviation from ideality factor versus q/3kT curve are in close agreement with the values obtained from the barrier height versus q/2kT variation. As a result, it can be concluded that the temperature dependent electrical characteristics of Au/4H-SiC can be successfully commented on the basis of the thermionic emission theory with both models.

  7. A fully enclosed, compact standard lightning impulse generator for testing ultra-high-voltage-class gas-insulated switchgears with high capacitance

    Wen, Tao; Zhang, Qiaogen; Zhang, Lingli; Zhao, Junping; Liu, Xuandong; Li, Xiaoang; Guo, Can; You, Haoyang; Chen, Weijiang; Yin, Yu; Shi, Weidong

    2016-03-01

    At present, conducting standard lightning impulse (LI) tests in the field for gas-insulated switchgear (GIS) equipment is difficult because of the high capacitance of the test equipment and large circuit inductance of traditional impulse devices, which leads to a wavefront time Tf ≥ 2.5 μs. A novel fully enclosed, compact standard LI generator for testing ultra-high-voltage-class GIS equipment with high capacitance is presented to solve the problem of Tf exceeding the standard during LI voltage tests for actual large-sized equipment. The impulse generator is installed in a metal vessel filled with SF6 or SF6/N2 gas mixture at a pressure of 0.3-0.5 MPa, providing a more compact structure and a lower series inductance. A newly developed conical voltage sensor is used to accurately measure the output voltage waveform. Two test modes (via bushing docking and direct docking) for the GIS test based on the impulse generator are introduced. Calculation results show that the impulse generator can generate an LI test waveform following the present IEC standard for the test of equipment with capacitance >10 000 pF.

  8. 多次级高压变压器的分布电容%Distributed capacitance of multi-level high-voltage transformer

    谢飞燕; 张灵迪

    2012-01-01

    The distributed capacitance is inherent in the multi-level high-voltage transformer parasitic parameters, which directly affects the circuit performance. According to the generation mechanism of distributed capacitance, through comparing the traditional method of winding and the technology of PCB Diego around, the measured waveform is used to illustrate the influence of distributed capacitance on circuit performance.%分布电容是多次级高压变压器固有的寄生参数,它直接影响电路的工作性能。本文从分布电容的产生机理出发,通过传统绕制和PCB迭绕两种工艺的比较,最后以实测波形来说明了分布电容对电路性能的影响。

  9. 中压配电网串联电容补偿调压技术研究及应用%Study and application of voltage regulation technology by series capacitance compensation in medium voltage distribution network

    吴勇海; 蔡金锭

    2012-01-01

    The medium voltage distribution lines with long power supply radius and broad load fluctuations, because of the larger voltage loss in the line, often result in low voltage and voltage fluctuation in the load-side, which is difficult to meet the requirements of voltage quality. The compensation of capacitor is calculated precisely under different loads, and then the maximum transmission capacity of the medium voltage radial line with the series capacitance compensation can be gotten when the voltage of the end line is stable. Simulation using Matlab/Simulink is carried out and the results verify the correctness of this calculation. The series capacitance compensator is applied to 10 kV radiation line and its normal operation and stable load-side voltage verify the practicality of series capacitance compensation.%对于供电半径大、负荷波动较大的中压配电线路,由于线路中的电压损耗较大,常常造成负荷端的电压值偏低、电压波动大,难以满足电压质量要求.通过对不同负荷情况下,对补偿电容量的精确计算,得到中压辐射线路的在电容串联补偿下稳定末端电压的最大输送容量,并通过Matlab仿真验证.在某电力公司10 kV线路接上串联电容补偿器,其正常运行并且稳定负荷侧电压验证了串联电容补偿调压的实用性.

  10. Application of capacitance compensation in voltage adjustment of distribution power system%电容补偿在配电网电压调节中的应用

    张先泰; 蔡金锭; 丁智华; 陈廉青

    2011-01-01

    针对某些配电网负荷电压水平不满足要求和电压波动较大的问题,提出基于串联电容补偿的配电网负荷电压调节与稳定方法.通过在配电线路上串入可调电容,根据电容电压损耗与线路原电感电压损耗极性相反的特征,在负荷波动的情况下利用电容电压抵偿线路电感电压即可调节和稳定负荷侧电压.通过实时采样负荷功率,计算补偿电路的晶闸管触发角,调节电容补偿量以稳定负荷侧电压.利用Matlab的PSB模块搭建了一条带有晶闸管控制串联电容补偿的配电线路,仿真结果验证了理论分析的正确性.%The series capacitance compensation is applied to realize the load voltage adjustment and stabilization for those distribution power systems which have large voltage fluctuation or could not meet the requirement of load voltage level. The adjustable capacitor is inserted into the distribution line and its voltage is used to compensate the line inductor voltage when load fluctuates,which could adjust and stabilize the voltage. The load power is sampled and the thyristor trigger angle of compensation circuit is calculated in real time to adjust the level of capacitance compensation. A distribution system model with series capacitance compensation is built with PSB module in Matlab and the simulative result verifies the correctness of the theoretical analysis.

  11. Voltage stability in low voltage microgrids in aspects of active and reactive power demand

    Parol Mirosław

    2016-03-01

    Full Text Available Low voltage microgrids are autonomous subsystems, in which generation, storage and power and electrical energy consumption appear. In the paper the main attention has been paid to the voltage stability issue in low voltage microgrid for different variants of its operation. In the introduction a notion of microgrid has been presented, and also the issue of influence of active and reactive power balance on node voltage level has been described. Then description of voltage stability issue has been presented. The conditions of voltage stability and indicators used to determine voltage stability margin in the microgrid have been described. Description of the low voltage test microgrid, as well as research methodology along with definition of considered variants of its operation have been presented further. The results of exemplary calculations carried out for the daily changes in node load of the active and reactive power, i.e. the voltage and the voltage stability margin indexes in nodes have been presented. Furthermore, the changes of voltage stability margin indexes depending on the variant of the microgrid operation have been presented. Summary and formulation of conclusions related to the issue of voltage stability in microgrids have been included at the end of the paper.

  12. Fully parameterized model of a voltage-driven capacitive coupled micromachined ohmic contact switch for RF applications

    A comprehensive and completely parameterized model is proposed to determine the related electrical and mechanical dynamic system response of a voltage-driven capacitive coupled micromechanical switch. As an advantage over existing parameterized models, the model presented in this paper returns within few seconds all relevant system quantities necessary to design the desired switching cycle. Moreover, a sophisticated and detailed guideline is given on how to engineer a MEMS switch. An analytical approach is used throughout the modelling, providing representative coefficients in a set of two coupled time-dependent differential equations. This paper uses an equivalent mass moving along the axis of acceleration and a momentum absorption coefficient. The model describes all the energies transferred: the energy dissipated in the series resistor that models the signal attenuation of the bias line, the energy dissipated in the squeezed film, the stored energy in the series capacitor that represents a fixed separation in the bias line and stops the dc power in the event of a short circuit between the RF and dc path, the energy stored in the spring mechanism, and the energy absorbed by mechanical interaction at the switch contacts. Further, the model determines the electrical power fed back to the bias line. The calculated switching dynamics are confirmed by the electrical characterization of the developed RF switch. The fabricated RF switch performs well, in good agreement with the modelled data, showing a transition time of 7 µs followed by a sequence of bounces. Moreover, the scattering parameters exhibit an isolation in the off-state of >8 dB and an insertion loss in the on-state of <0.6 dB up to frequencies of 50 GHz. The presented model is intended to be integrated into standard circuit simulation software, allowing circuit engineers to design the switch bias line, to minimize induced currents and cross actuation, as well as to find the mechanical structure dimensions

  13. Phospholipase A2 activation by hydrogen peroxide during in vitro capacitation of buffalo spermatozoa.

    Shit, Sanjoy; Atreja, S K

    2004-05-01

    Progressively motile, washed buffalo spermatozoa (50 x 10(6) cells in 0.5 ml) were in vitro capacitated in HEPES containing Bovine Gamete Medium 3 (BGM3) in presence of heparin (10 microg/ml), and different concentrations of hydrogen peroxide (10 to 100 microM). Spermatozoa (60%) were capacitated in presence of heparin compared to 56% in presence of 25 microM H2O2 (optimally found suitable for capacitation). The extent of capacitation was measured in terms of acrosome reaction (AR) induced by lysophosphatidyl choline (100 microg/ml). The acrosome reacted cells were counted after triple staining. Catalase (100 microg/ml) significantly reduced the sperm capacitation to 16-18% when added with H2O2, or alone in the capacitation medium. Phospholipase A2 activity of spermatozoa increased linearly up to 50 microM H2O2 concentration included in the assay system. Moreover, significant increase in phospholipase A2 activity was observed after capacitation by both, the heparin and 25 microM H2O2. The activity was always higher in acrosome reacted cells. PMID:15233473

  14. Nonlinear Quantum Capacitance

    Wang, B; Zhao, X; Guo, H; Wang, J.

    1999-01-01

    We analyze the nonlinear voltage dependence of electrochemical capacitance for nanoscale conductors. This voltage dependence is due to the finite density of states of the conductors. Within Hartree theory we derive an exact expression for the electrochemical capacitance–voltage curve for a parallel plate system. The result suggests a quantum scanning capacitance microscopy at the nanoscale: by inverting the capacitance–voltage expression one is able to deduce the local spectral function of th...

  15. Program-Controlled High Voltage Module in Active Voltage Dividers(AVD) for MPGD

    Ginting, Muhammad Fadhil

    2016-01-01

    Micro Pattern Gas Detectors (MPGD) applications are rapidly developing and became an important part of upgrades for the LHC detectors. RD51/CERN have worked on Active Voltage Divider (AVD) technology for multistage MPGDs, One of the next developments for the AVD is to design and integrate high voltage module in a single box. The Program-Controlled High Voltage Module, part of one AIDA2020 project, has been successfully designed and developed, and can be integrated in AVD design.

  16. Control of electron heating and ion energy distributions in capacitive plasmas by voltage waveform tailoring based on a novel power supply and impedance matching

    Berger, Birk; Franek, James; Brandt, Steven; Liese, Martin; Barthel, Matthias; Schuengel, Edmund; Koepke, Mark; Schulze, Julian

    2015-09-01

    We present a novel RF power supply and impedance matching to drive technological plasmas with customized voltage waveforms. By adjusting the individual phases and amplitudes of multiple consecutive harmonics any voltage waveform can be realized as a customized finite Fourier series. This RF supply system is easily adaptable to any technological plasma for industrial applications and allows the commercial utilization of process optimization based on voltage waveform tailoring for the first time. Here, this system is tested on a capacitive discharge based on three consecutive harmonics of 13.56 MHz in argon. The effect of changing the shape of the driving voltage waveform on the electron heating and sheath dynamics is investigated by Phase Resolved Optical Emission Spectroscopy (PROES) for different electrode gaps, pressures, and applied voltages. At low pressure the results are correlated with ion energy distribution functions measured at both electrodes. Tuning the phases between the applied harmonics results in an electrical control of the DC self-bias and the mean ion energy. A comparison with the reference case of a dual-frequency discharge reveals that using more than two consecutive harmonics significantly enlarges the control range of the mean ion energy.

  17. A novel single-stage isolated ac/dc converter with quasi-resonant zero-voltage-switching with a modified forward converter adopting capacitive output filter

    Kim, Myung-Bok; Youn, Myung-Joong

    2010-07-01

    A new single-stage isolated ac-dc converter, which can achieve a better efficiency and a better power factor, is proposed. It is based on a general forward topology so that it can utilise the transformer more than converters based on flyback topology. In addition, since the capacitive output filter is adopted instead of an inductive type filter, the voltages on the secondary rectifiers can be clamped to the output voltage; meanwhile, the capacitor used in the output filter can be utilised for the resonance with the leakage inductance, and the turn-off loss in the primary main switch and the dissipative loss in the snubber can be reduced. Moreover, since this converter can be operated at the boundary conduction mode, the line input current can be automatically shaped as the waveform of a line voltage and quasi-resonant zero voltage switching can be also obtained. Therefore, it features higher efficiency, lower voltage stress and a smaller-sized transformer than other topologies. A 100 W prototype has been built and tested for the verification of the proposed topology.

  18. Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance

    Ye, Dong; Yu, Yao; Tang, Jie; Liu, Lin; Wu, Yue

    2016-05-01

    Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as an electrode material for flexible supercapacitors. However, pristine CC has such a low surface area and poor electrochemical activity that the energy storage capability is usually very poor. Herein, we report a green method, two-step electrochemical activation in an aqueous solution of inorganic salts, to significantly enhance the capacitance of CC for supercapacitor application. Micro-cracks, exfoliated carbon fiber shells, and oxygen-containing functional groups (OFGs) were introduced onto the surface of the carbon filament. This resulted in an enhancement of over two orders of magnitude in capacitance compared to that of the bare CC electrode, reaching up to a maximum areal capacitance of 505.5 mF cm-2 at the current density of 6 mA cm-2 in aqueous H2SO4 electrolyte. Electrochemical reduction of CC electrodes led to the removal of most electrochemically unstable surface OFGs, resulting in superior charging/discharging rate capability and excellent cycling stability. Although the activated CC electrode contained a high-level of surface oxygen functional groups (~15 at%), it still exhibited a remarkable charging-discharging rate capability, retaining ~88% of the capacitance when the charging rate increased from 6 to 48 mA cm-2. Moreover, the activated CC electrode exhibited excellent cycling stability with ~97% capacitance remaining after 10 000 cycles at a current density of 24 mA cm-2. A symmetrical supercapacitor based on the activated CC exhibited an ideal capacitive behavior and fast charge-discharge properties. Such a simple, environment-friendly, and cost-effective strategy to activate CC shows great potential in the fabrication of high-performance flexible supercapacitors.Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as

  19. Comparison of capacitive behavior of activated carbons with different pore structures in aqueous and nonaqueous systems

    ZHOU Shao-yun; LI Xin-hai; WANG Zhi-xing; GUO Hua-jun; PENG Wen-jie

    2008-01-01

    The pore structures of two activated carbons from sawdust with KOH activation and coconut-shell with steam activation for supercapacitor were analyzed by N2 adsorption method. The electrochemical properties of both activated carbons in 6mol/L KOH solution and 1mol/L Et4NPF4/PC were compared, and the effect of pore structure on the capacitance was investigated by cyclic voltammetry, AC impedance and charge-discharge measurements. The results indicate that the capacitance mainly depends on effective surface area, but the power property mainly depends on mesoporosity. At low specific current (1A/g), the maximum specific capacitances of 276.3F/g in aqueous system and 123.9F/g in nonaqueous system can be obtained from sawdust activated carbon with a larger surface area of 1808m2/g, but at a high specific current, the specific capacitance of coconut-shell activated carbon with a higher mesoporosity of 75.1% is more excellent. Activated carbon by KOH activation is fitter for aqueous system and that by steam activation is fitter for nonaqueous system.

  20. Temperature dependent junction capacitance-voltage characteristics of Ni embedded TiN/SiO{sub 2}/p-Si metal–insulator–semiconductor structure

    Panda, J.; Nath, T. K., E-mail: tnath@phy.iitkgp.ernet.in [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302 (India); Chattopadhyay, S. [Department of Physics and Meteorology, Indian Institute of Technology Kharagpur, Kharagpur, West Bengal 721302 (India); Amity Institute of Nano Technology, Amity University, Sector-125, Noida, Uttar Pradesh 201313 (India)

    2013-12-14

    This work presents the junction capacitance–voltage characteristics of highly textured/epitaxial Ni nanoparticle embedded in TiN matrix (TiN(Ni)) metal-insulator-semiconductor TiN(Ni)/SiO{sub 2}/p-Si (100) heterojunction in the temperature range of 10–300 K. This heterojunction behaves as metal-semiconductor junction with unavoidable leakage through native oxide SiO{sub 2} layer. The clockwise hysteresis loop has been observed in the capacitance-voltage characteristics measured at various frequencies mainly due to presence of trap centers at the TiN(Ni)/SiO{sub 2} interface and these are temperature dependent. The spin-dependent trap charge effect at the interface influences the quadratic nature of the capacitance with magnetic field. The junction magnetocapacitance (JMC) is observed to be dependent on both temperature and frequency. The highest JMC of this heterojunction has been observed at 200 K at higher frequencies (100 kHz–1 MHz). It is found that there is not much effect of band structure modification under magnetic field causing the JMC.

  1. Electrochemical activation of carbon cloth in aqueous inorganic salt solution for superior capacitive performance.

    Ye, Dong; Yu, Yao; Tang, Jie; Liu, Lin; Wu, Yue

    2016-05-21

    Carbon cloth (CC) is an inexpensive and highly conductive textile with excellent mechanical flexibility and strength; it holds great promise as an electrode material for flexible supercapacitors. However, pristine CC has such a low surface area and poor electrochemical activity that the energy storage capability is usually very poor. Herein, we report a green method, two-step electrochemical activation in an aqueous solution of inorganic salts, to significantly enhance the capacitance of CC for supercapacitor application. Micro-cracks, exfoliated carbon fiber shells, and oxygen-containing functional groups (OFGs) were introduced onto the surface of the carbon filament. This resulted in an enhancement of over two orders of magnitude in capacitance compared to that of the bare CC electrode, reaching up to a maximum areal capacitance of 505.5 mF cm(-2) at the current density of 6 mA cm(-2) in aqueous H2SO4 electrolyte. Electrochemical reduction of CC electrodes led to the removal of most electrochemically unstable surface OFGs, resulting in superior charging/discharging rate capability and excellent cycling stability. Although the activated CC electrode contained a high-level of surface oxygen functional groups (∼15 at%), it still exhibited a remarkable charging-discharging rate capability, retaining ∼88% of the capacitance when the charging rate increased from 6 to 48 mA cm(-2). Moreover, the activated CC electrode exhibited excellent cycling stability with ∼97% capacitance remaining after 10 000 cycles at a current density of 24 mA cm(-2). A symmetrical supercapacitor based on the activated CC exhibited an ideal capacitive behavior and fast charge-discharge properties. Such a simple, environment-friendly, and cost-effective strategy to activate CC shows great potential in the fabrication of high-performance flexible supercapacitors. PMID:27141910

  2. 周边电场对电容分压型 EVT 准确度的影响研究%Study on the Surrounding Influence of Electric Field on Accuracy of Electronic Voltage Transformer with Capacitive Voltage Divider

    冯宇; 王晓琪; 艾兵; 吴光斌; 罗睿希; 江波

    2014-01-01

    A lot of problems occur in the application of electronic transformer for smart substation, where stray capaci-tance and proximity effects caused by the surrounding electric field are the main factors for capacitive electronic volt-age transformer accuracy.Interference mechanism and mathematical model are analyzed firstly with studying the influ-ence of electric field on the accuracy of EVT.The finite element model of a typical capacitance-divide EVT in opera-tion has been built.The influence of stray capacitance and proximity effect on EVT accuracy has been simulated and the shielding effectiveness has also been evaluated for the high voltage terminal shield.The simulation results show that the stray capacitance of ground terminal is greater than the that of high voltage terminal, EVT divide ratio effected by stray capacitance will be reduced along with the enlarged distance between EVT or between EVT and grounded ob-jects, the divide ratio and ratio error will get greater when the voltage of adjacent phase increased, and the high volt-age terminal shield can reduce the influence of proximity effect by improving potential distribution which reduced the horizontal component of electric field.The conclusion can be taken as the ssvaluable reference for optimization design of EVT.%电子式互感器在智能变电站应用中出现了不少问题,其中由周边电场所引起的杂散电容与邻近效应是影响电容分压型电子式电压互感器准确度的主要因素之一。首先分析了周边电场对电容分压型EVT准确度的干扰机理与数学模型,其次建立了典型在运电容分压型EVT的有限元计算模型,以此为基础仿真研究了杂散电容与邻近效应对其准确度的影响,并对高压端屏蔽罩的屏蔽效能进行了评估。仿真结果表明:地端杂散电容大于高压端杂散电容,杂散电容对EVT分压比的影响随着EVT与接地体之间的距离增大或三相EVT之间的距离增大而减

  3. Estrous sheep serum enables in vitro capacitation of ram spermatozoa while preventing caspase activation.

    Del Olmo, E; García-Álvarez, O; Maroto-Morales, A; Ramón, M; Jiménez-Rabadán, P; Iniesta-Cuerda, M; Anel-Lopez, L; Martinez-Pastor, F; Soler, A J; Garde, J J; Fernández-Santos, M R

    2016-01-15

    Estrous sheep serum (ESS) is considered the most efficient agent for in vitro capacitation of ram spermatozoa. We have explored the relationship between caspase activation and capacitation in ram. Semen samples from 17 rams were cryopreserved. In vivo fertility was evaluated after intrauterine artificial insemination. Samples were submitted to four treatments: control, ESS (10%), caspase inhibitor (Z-VAD-FMK), and estrous ewe serum plus caspase inhibitor (I + E). Sperm samples were incubated for 30 minutes at 38.5 °C and 5% CO2 and analyzed with flow cytometry for mitochondrial membrane potential (MitoTracker deep red), sperm viability and apoptosis-like changes (YO-PRO-1/propidium iodide), acrosomal status (peanut agglutinin-fluorescein isothiocyanate), membrane fluidity (merocyanine 540), and caspase activity (Vybrant FAM kits for polycaspases, caspase-8, and caspases 3-7). Estrous sheep serum induced changes compatible with capacitation, doubling the proportion of viable spermatozoa with increased merocyanine 540 and increasing YO-PRO-1(+) and acrosome-reacted spermatozoa (P < 0.05). Incubation increased the proportion of spermatozoa with activated caspases (P < 0.05), which was abolished by the treatments. We detected a simultaneous decrease in the proportion of the viable and caspase(-) spermatozoa after the incubation, which was prevented by the presence of estrous ewe serum (P < 0.05). The analysis of caspases 3/7 and 8 resulted in less marked differences. Fertility was positively related to viability and inactivated caspases and negatively to viable-capacitated spermatozoa and active caspases. In vitro induction of capacitation in thawed ram spermatozoa by using ESS suggests a downregulation in apoptotic pathways. However, males with the lowest fertility showed parameters similar to high-fertility males, suggesting that other factors were involved apart from capacitation and/or caspase activation. PMID:26474680

  4. Capacitance enhancement of polyaniline coated curved-graphene supercapacitors in a redox-active electrolyte

    Chen, Wei

    2013-01-01

    We show, for the first time, a redox-active electrolyte in combination with a polyaniline-coated curved graphene active material to achieve significant enhancement in the capacitance (36-92% increase) compared to supercapacitors that lack the redox-active contribution from the electrolyte. The supercapacitors based on the redox-active electrolyte also exhibit excellent rate capability and very long cycling performance (>50 000 cycles). This journal is © The Royal Society of Chemistry.

  5. The effect of pulse voltage and capacitance on biosorption of uranium by biomass derived from whiskey distillery spent wash

    Biosorption of uranium by residual biomass from The Old Bushmill's Distillery Co. Ltd., Bushmills, Co. Antrim, Northern Ireland, following exposure to short and intense electric pulses has been examined. The biomass was prepared from the distillery spent wash and consisted of non-viable yeast and bacterial cells. As shown previously, untreated biomass had a maximum biosorption capacity of 170 mg uranium/g dry weight biomass. When biosorption reactions were placed between two electrodes and exposed to electric pulses with field strengths ranging from 1.25-3.25 kV/cm at a capacitance of 25 μF, biosorption increased from 170 mg of uranium to 275 mg uranium/g dry weight biomass. The data were obtained from biosorption isotherm analyses and taken as the degree of biosorption at residual uranium concentrations of 3 mM. In addition, when the capacitance of the electric pulses increased from 0.25 μF to 25 μF at a fixed pulse field strength the degree of biosorption increased from 210 mg uranium to 240 mg uranium/g dry weight biomass. The results suggest that application of short and intense electric pulses to biosorption reactions may play an important role in enhancing microbial biosorption of toxic metals/radionuclides from waste water streams. (orig.)

  6. The effect of pulse voltage and capacitance on biosorption of uranium by biomass derived from whiskey distillery spent wash

    Bustard, M.; Rollan, A.; McHale, A.P. [Biotechnology Research Group, School of Applied Biological and Chemical Sciences, University of Ulster (United Kingdom)

    1999-01-01

    Biosorption of uranium by residual biomass from The Old Bushmill`s Distillery Co. Ltd., Bushmills, Co. Antrim, Northern Ireland, following exposure to short and intense electric pulses has been examined. The biomass was prepared from the distillery spent wash and consisted of non-viable yeast and bacterial cells. As shown previously, untreated biomass had a maximum biosorption capacity of 170 mg uranium/g dry weight biomass. When biosorption reactions were placed between two electrodes and exposed to electric pulses with field strengths ranging from 1.25-3.25 kV/cm at a capacitance of 25 {mu}F, biosorption increased from 170 mg of uranium to 275 mg uranium/g dry weight biomass. The data were obtained from biosorption isotherm analyses and taken as the degree of biosorption at residual uranium concentrations of 3 mM. In addition, when the capacitance of the electric pulses increased from 0.25 {mu}F to 25 {mu}F at a fixed pulse field strength the degree of biosorption increased from 210 mg uranium to 240 mg uranium/g dry weight biomass. The results suggest that application of short and intense electric pulses to biosorption reactions may play an important role in enhancing microbial biosorption of toxic metals/radionuclides from waste water streams. (orig.) With 2 tabs., 10 refs.

  7. Capacitance-voltage characteristics of (Al/Ti)/Al{sub 2}O{sub 3}/n-GaN MIS structures

    Ivanov, P. A., E-mail: Pavel.Ivanov@mail.ioffe.ru; Potapov, A. S.; Nikolaev, A. E.; Lundin, V. V.; Sakharov, A. V.; Tsatsulnikov, A. F. [Russian Academy of Sciences, Ioffe Institute (Russian Federation); Afanas’ev, A. V.; Romanov, A. A.; Osachev, E. V. [St. Petersburg Electrotechnical University LETI (Russian Federation)

    2015-08-15

    The capacitance-voltage characteristics of (Al/Ti)/Al{sub 2}O{sub 3}/n-GaN metal—insulator-semiconductor (MIS) structures are measured and analyzed. n-Type GaN films are grown on sapphire (0001) substrates by the metal-organic chemical vapor deposition method. An aluminum-oxide layer with a thickness of 60 nm is deposited onto the surface of GaN by the method of atomic-layer deposition from the gas phase. Metallic contacts are deposited by the electron-beam evaporation of titanium and aluminum in vacuum. According to the measurement results, the breakdown-field strength of the oxide, its dielectric constant, and the integrated electron density of states at the oxide-semiconductor interface are 5 × 10{sup 6} V/cm, 7.5, and 3 × 10{sup 12} cm{sup −2}, respectively.

  8. High sensitivity measurement system for the direct-current, capacitance-voltage, and gate-drain low frequency noise characterization of field effect transistors

    Giusi, G.; Giordano, O.; Scandurra, G.; Rapisarda, M.; Calvi, S.; Ciofi, C.

    2016-04-01

    Measurements of current fluctuations originating in electron devices have been largely used to understand the electrical properties of materials and ultimate device performances. In this work, we propose a high-sensitivity measurement setup topology suitable for the automatic and programmable Direct-Current (DC), Capacitance-Voltage (CV), and gate-drain low frequency noise characterization of field effect transistors at wafer level. Automatic and programmable operation is particularly useful when the device characteristics relax or degrade with time due to optical, bias, or temperature stress. The noise sensitivity of the proposed topology is in the order of fA/Hz1/2, while DC performances are limited only by the source and measurement units used to bias the device under test. DC, CV, and NOISE measurements, down to 1 pA of DC gate and drain bias currents, in organic thin film transistors are reported to demonstrate system operation and performances.

  9. Admittance–voltage profiling of AlxGa1−xN/GaN heterostructures: Frequency dependence of capacitance and conductance

    Admittance–voltage profiling of AlxGa1−xN/GaN heterostructures was used to determine the frequency dependent capacitance and conductance of FET devices in the frequency range from 50 Hz to 1 MHz. The nominally undoped low pressure metal-organic vapor-phase epitaxy structures were grown with an Al-content of 30%. An additional 1 nm thick AlN interlayer was placed in one structure before the Al0.3Ga0.7N layer growth. For frequencies below 108 Hz it is convenient to use equivalent circuits to represent electric or dielectric properties of a material, a method widely used, for example, in impedance spectroscopy. We want to emphasize the relation between frequency dependent admittance–voltage profiling and the corresponding equivalent circuits to the complex dielectric function. Debye and Drude models are used for the description of the frequency dependent admittance profiles in a range of depletion onset of the two-dimensional electron gas. Capacitance- and conductance-frequency profiles are fitted in the entire measured range by combining both models. Based on our results, we see contributions to the two-dimensional electron gas for our samples from surface states (80%) as well as from background doping in the Al0.3Ga0.7N barriers (20%). The specific resistance of the layers below the gate is above 105 Ω cm for both samples and increases with increasing negative bias, i.e., the layers below the gate are essentially depleted. We propose that the resistance due to free charge carriers, determined by the Drude model, is located between gate and drain and, because of the AlN interlayer, the resistance is lowered by a factor of about 30 if compared to the sample without an AlN layer

  10. Effect of SrTiO3 thickness on the capacitance-voltage characteristics of (La,Sr)CoO3/(Pb,La)(Zr,Ti)O3/SrTiO3/LaVO3 epitaxial heterostructures

    We report the effect of SrTiO3 thickness on the capacitance-voltage (C-V) characteristics of (La,Sr)CoO3/(Pb,La)(Zr,Ti)O3/SrTiO3/LaVO3 metal-ferroelectric-insulator-semiconductor (MFIS) epitaxial heterostructures. The C-V measurement of the heterostructure exhibited the asymmetry of capacitance with respect to gate bias. Within the given thickness range (5-30 nm), the amount of capacitance reduction at positive gate bias and the rapidness of capacitance reduction decreased with increasing SrTiO3 thickness, which is consistent with the C-V characteristics of conventional silicon-based MFIS capacitors. These results suggest that quantitative understanding on the electrical behavior of oxide heterostructures is possible with C-V analysis, with potentially important implications on their device applications. (orig.)

  11. Performance Analysis and Test of Noise in Differential Capacitance to Voltage Conversion Circuit%差分电容电压转换电路噪声性能分析及测试

    张霞; 胡世昌; 朱辉杰

    2011-01-01

    本文对电容检测式加速度计系统中广泛采用的差分电容电压转换电路建立了电容电压转换电路的等效噪声模型,并对双运放集成电路芯片所构成的差分电容电压转换电路的本底噪声以及仪表放大器输出端的噪声进行了测试,将电容电压转换电路本底噪声中的差模噪声分量和共模噪声分量进行了分离.测试结果表明影响加速度计系统噪声性能的差模噪声分量占电容电压转换电路本底噪声的50%.%This paper presents an equivalent noise model of differential capacitance to voltage conversion circuit which is widely used in capacitive sensing accelerometers. The noise floors of the capacitance to voltage conversion circuit realized by dual amplifiers (two in a package) and the instrumentation amplifier are measured. The common-mode noise and the difference-mode noise in the noise floor of the capacitance to voltage conversion circuit can be calculated. The test results show that the difference-mode noise, which would affect the resolution of the capacitive sensing accelerometer system, constitutes nearly half the noise floor of the capacitance to voltage conversion circuit.

  12. Formaldehyde assay by capacitance versus voltage and impedance measurements using bi-layer bio-recognition membrane.

    Ben Ali, M; Korpan, Y; Gonchar, M; El'skaya, A; Maaref, M A; Jaffrezic-Renault, N; Martelet, C

    2006-12-15

    A novel formaldehyde sensitive biosensor based on bacterial formaldehyde dehydrogenase (FDH) as a bio-recognition element has been developed. The bio-recognition membrane had bi-layer architecture and consisted of FDH, cross-linked with albumin, and of the cofactor NAD at a high concentration level (first layer). The second layer was a negatively charged Nafion membrane, which prevented a leakage of negatively charged NAD molecules from the bio-membrane. As transducers, gold electrodes SiO(2)/Si/SiO(2)/Ti/Au and electrolyte-insulator-semiconductor Si/SiO(2) (EIS) structures have been used. Changes in capacitance and impedance properties of the bio-recognition membrane have been used for monitoring formaldehyde concentration in a bulk solution. It has been shown that formaldehyde can be detected within a concentration range from 1 microM to 20mM depending on the type of transduction used, with a detection limit of 1 and 100 microM for gold-based and EIS-based transducers, respectively. PMID:16516460

  13. Asymmetric Electrodes Constructed with PAN-Based Activated Carbon Fiber in Capacitive Deionization

    Mingzhe Li; Yingzhi Chen; Zheng-Hong Huang; Feiyu Kang

    2014-01-01

    Capacitive deionization (CDI) method has drawn much attention for its low energy consumption, low pollution, and convenient manipulation. Activated carbon fibers (ACFs) possess high adsorption ability and can be used as CDI electrode material. Herein, two kinds of PAN-based ACFs with different specific surface area (SSA) were used for the CDI electrodes. The CDI performance was investigated; especially asymmetric electrodes’ effect was evaluated. The results demonstrated that PAN-based ACFs s...

  14. Highly porous activated carbons from resource-recovered Leucaena leucocephala wood as capacitive deionization electrodes.

    Hou, Chia-Hung; Liu, Nei-Ling; Hsi, Hsing-Cheng

    2015-12-01

    Highly porous activated carbons were resource-recovered from Leucaena leucocephala (Lam.) de Wit. wood through combined chemical and physical activation (i.e., KOH etching followed by CO2 activation). This invasive species, which has severely damaged the ecological economics of Taiwan, was used as the precursor for producing high-quality carbonaceous electrodes for capacitive deionization (CDI). Carbonization and activation conditions strongly influenced the structure of chars and activated carbons. The total surface area and pore volume of activated carbons increased with increasing KOH/char ratio and activation time. Overgasification induced a substantial amount of mesopores in the activated carbons. In addition, the electrochemical properties and CDI electrosorptive performance of the activated carbons were evaluated; cyclic voltammetry and galvanostatic charge/discharge measurements revealed a typical capacitive behavior and electrical double layer formation, confirming ion electrosorption in the porous structure. The activated-carbon electrode, which possessed high surface area and both mesopores and micropores, exhibited improved capacitor characteristics and high electrosorptive performance. Highly porous activated carbons derived from waste L. leucocephala were demonstrated to be suitable CDI electrode materials. PMID:26135977

  15. Improvement in electrochemical capacitance of activated carbon from scrap tires by nitric acid treatment

    Han, Yan; Zhao, Ping-Ping; Dong, Xiao-Ting; Zhang, Cui; Liu, Shuang-Xi

    2014-12-01

    Activated carbon (AC) obtained from the industrial pyrolytic tire char is treated by concentrated nitric acid (AC-HNO3) and then used as the electrode material for supercapacitors. Surface properties and electrochemical capacitances of AC and ACHNO3 are studied. It is found that the morphology and the porous texture for AC and AC-HNO3 have little difference, while the oxygen content increases and functional groups change after the acid treatment. Electrochemical results demonstrate that the AC-HNO3 electrode displays higher specific capacitance, better stability and cycling performance, and lower equivalent series resistance, indicating that AC obtained from the industrial pyrolytic tire char treated by concentrated nitric acid is applicable for supercapacitors.

  16. Voltage-clamp frequency domain analysis of NMDA-activated neurons.

    Moore, L E; Hill, R H; Grillner, S

    1993-02-01

    1. Voltage and current-clamp steps were added to a sum of sine waves to measure the tetrodotoxin-insensitive membrane properties of neurons in the intact lamprey spinal cord. A systems analysis in the frequency domain was carried out on two types of cells that have very different morphologies in order to investigate the structural dependence of their electrophysiological properties. The method explicitly takes into account the geometrical shapes of (i) nearly spherical dorsal cells with one or two processes and (ii) motoneurons and interneurons that have branched dendritic structures. Impedance functions were analysed to obtain the cable properties of these in situ neurons. These measurements show that branched neurons are not isopotential and, therefore, a conventional voltage-clamp analysis is not valid. 2. The electrophysiological data from branched neurons were curve-fitted with a lumped soma-equivalent cylinder model consisting of eight equal compartments coupled to an isopotential cell body to obtain membrane parameters for both passive and active properties. The analysis provides a quantitative description of both the passive electrical properties imposed by the geometrical structure of neurons and the voltage-dependent ionic conductances determined by ion channel kinetics. The model fitting of dorsal cells was dominated by a one-compartment resistance and capacitance in parallel (RC) corresponding to the spherical, non-branched shape of these cells. Branched neurons required a model that contained both an RC compartment and a cable that reflected the structure of the cells. At rest, the electrotonic length of the cable was about two. Uniformly distributed voltage-dependent ionic conductance sites were adequate to describe the data at different membrane potentials. 3. The frequency domain admittance method in conjunction with a step voltage clamp was used to control and measure the oscillatory behavior induced by N-methyl-D-aspartate (NMDA) on lamprey spinal

  17. Voltage harmonics mitigation through hybrid active power filer

    Fast dynamic response, high efficiency, low cost and small size of power electronic converters have exponentially increased their use in modern power system which resulted in harmonically distorted voltage and currents. Voltage harmonics mainly caused by current harmonics are more dangerous as performance and expected operating life of other power system equipment are affected by harmonically distorted supply voltage. Electronic filter circuits are used to improve system power quality by mitigating adverse effects of harmonics. Hybrid filters having advantages of both passive and active filters are preferred to resolve the problem of harmonics efficiently and avoiding any chance of resonance. In this paper, a three phase three wire network is considered to supply an adjustable speed drive represented by a resistive load connected across a three phase bridge rectifier. Simulation of the considered system shows THD (Total Harmonic Distortion) of 18.91 and 7.61 percentage in supply current and voltage respectively. A HAPF (Hybrid Active Power Filter) is proposed to reduce these THD values below 5 percentage as recommended by IEEE Standard-519. P-Q theorem is used to calculate required parameters for proposed filter, which is implemented through hysteresis control. Simulation results confirm the effectiveness of the designed filter as THD for both current and voltage have reduced below allowable limit of 5 percentage. (author)

  18. Voltage Harmonics Mitigation through Hybrid Active Power Filter

    Anwer Ali Sahito

    2016-01-01

    Full Text Available Fast dynamic response, high efficiency, low cost and small size of power electronic converters have exponentially increased their use in modern power system which resulted in harmonically distorted voltage and currents. Voltage harmonics mainly caused by current harmonics are more dangerous as performance and expected operating life of other power system equipment are affected by harmonically distorted supply voltage. Electronic filter circuits are used to improve system power quality by mitigating adverse effects of harmonics. Hybrid filters having advantages of both passive and active filters are preferred to resolve the problem of harmonics efficiently and avoiding any chance of resonance. In this paper, a three phase three wire network is considered to supply an adjustable speed drive represented by a resistive load connected across a three phase bridge rectifier. Simulation of the considered system shows THD (Total Harmonic Distortion of 18.91 and 7.61% in supply current and voltage respectively. A HAPF (Hybrid Active Power Filter is proposed to reduce these THD values below 5% as recommended by IEEE Standard-519. P-Q theorem is used to calculate required parameters for proposed filter, which is implemented through hysteresis control. Simulation results confirm the effectiveness of the designed filter as THD for both current and voltage have reduced below allowable limit of 5%.

  19. Optical absorption of the anthracene and temperature-dependent capacitance-voltage characteristics of the Au/anthracene/n-Si heterojunction in metal-organic-semiconductor configuration

    Kaçus, H.; Aydoğan, Ş.; Ekinci, D.; Kurudirek, S. V.; Türüt, A.

    2015-11-01

    An anthracene film has been deposited on an n-type silicon to fabricate an Au/anthracene/n-Si junction device. The band gap of the anthracene film has been determined from the optical measurement as Eg=1.65 eV. After the fabrication of the Au/anthracene/n-Si junction device, temperature dependent capacitance-voltage characteristics in the range of 160-300 K were studied to obtain the junction parameters of the device. The diffusion potential, barrier height, Fermi energy level and donor concentration parameters have been determined from the linear 1/C2-V curves with reverse bias at all temperatures. Both Fermi energy level and the barrier height increased with the increasing temperature. Temperature-dependence of the barrier height has been attributed to inhomogeneous barrier, traps and interface states. The ionized donor concentrations have varied with the temperature in an unsystematic manner due to the trapping/de-trapping of the charges at various temperatures.

  20. Voltage-dependent capacitance behavior and underlying mechanisms in metal-insulator-metal capacitors with Al2O3-ZrO2-SiO2 nano-laminates

    Zhu, Bao; Liu, Wen-Jun; Wei, Lei; Ding, Shi-Jin

    2016-04-01

    Nano-laminates consisting of high-permittivity dielectrics and SiO2 have been extensively studied for radio frequency metal-insulator-metal (MIM) capacitors because of their superior voltage linearity and low leakage current. However, there are no reports on the capacitance-voltage (C-V) characteristics at a high sweep voltage range. In this work, an interesting variation in the voltage-dependent capacitance that forms a ‘ω’-like shape is demonstrated for the MIM capacitors with Al2O3/ZrO2/SiO2 nano-laminates. As the thickness ratio of the SiO2 film to the total insulator increases to around 0.15, the C-V curve changes from an upward parabolic shape to a ‘ω’ shape. This can be explained based on the competition between the orientation polarization from SiO2 and the electrode polarization from Al2O3 and ZrO2. When the SiO2 film is very thin, the electrode polarization dominates in the MIM capacitor, generating a positive curvature C-V curve. When the thickness of SiO2 is increased, the orientation polarization is enhanced and thus both polarizations are operating in the MIM capacitors. This leads to the appearance of a multiple domain C-V curve containing positive and negative curvatures. Therefore, good consistency between the experimental results and the theoretical simulations is demonstrated. Such voltage-dependent capacitance behavior is not determined by the stack structure of the insulator, measurement frequency and oscillator voltage, but by the thickness ratio of the SiO2 film to the whole insulator. These findings are helpful to engineer MIM capacitors with good voltage linearity.

  1. Enhanced Capacitive Performance of N-Doped Activated Carbon from Petroleum Coke by Combining Ammoxidation with KOH Activation.

    Zhang, Yan; Zhang, Yu; Huang, Jufeng; Du, Dongfeng; Xing, Wei; Yan, Zifeng

    2016-12-01

    Low cost with high specific capacitance and energy density is the critical and main requirement for practical supercapacitors. A novel N-doped activated carbon was fabricated by KOH activation of petroleum coke and ammonia treatment. The as-prepared carbon exhibits a high specific surface area (1875 m(2) g(-1)), excellent conductivity (57 S m(-1)), and rich nitrogen level (4.0 wt%). Those outstanding characters result in this porous carbon a hopeful electrode material for electrochemical supercapacitors. It shows high specific capacitance (up to 299 F g(-1)) and superior rate capability (76 % retention ratio at 20 A g(-1)) in 30 wt% KOH aqueous electrolyte. This efficient treatment method ensures its prosperous application in energy storage systems. PMID:27167734

  2. Enhanced Capacitive Performance of N-Doped Activated Carbon from Petroleum Coke by Combining Ammoxidation with KOH Activation

    Zhang, Yan; Zhang, Yu; Huang, Jufeng; Du, Dongfeng; Xing, Wei; Yan, Zifeng

    2016-05-01

    Low cost with high specific capacitance and energy density is the critical and main requirement for practical supercapacitors. A novel N-doped activated carbon was fabricated by KOH activation of petroleum coke and ammonia treatment. The as-prepared carbon exhibits a high specific surface area (1875 m2 g-1), excellent conductivity (57 S m-1), and rich nitrogen level (4.0 wt%). Those outstanding characters result in this porous carbon a hopeful electrode material for electrochemical supercapacitors. It shows high specific capacitance (up to 299 F g-1) and superior rate capability (76 % retention ratio at 20 A g-1) in 30 wt% KOH aqueous electrolyte. This efficient treatment method ensures its prosperous application in energy storage systems.

  3. Module Eleven: Capacitance; Basic Electricity and Electronics Individualized Learning System.

    Bureau of Naval Personnel, Washington, DC.

    In this module the student will learn about another circuit quantity, capacitance, and discover the effects of this component on circuit current, voltage, and power. The module is divided into seven lessons: the capacitor, theory of capacitance, total capacitance, RC (resistive-capacitive circuit) time constant, capacitive reactance, phase and…

  4. Enhancing capacitive deionization performance of electrospun activated carbon nanofibers by coupling with carbon nanotubes.

    Dong, Qiang; Wang, Gang; Wu, Tingting; Peng, Senpei; Qiu, Jieshan

    2015-05-15

    Capacitive deionization (CDI) is an alternative, effective and environmentally friendly technology for desalination of brackish water. The performance of the CDI device is highly determined by the electrode materials. In this paper, a composite of carbon nanotubes (CNTs) embedded in activated carbon nanofiber (ACF) was prepared by a direct co-electrospinning way and subsequent CO2 activation. The introduction of CNTs can greatly improve the conductivity while the CO2-mediated activation can render the final product with high porosity. As such, the hybrid structure can provide an excellent storage space and pathways for ion adsorption and conduction. When evaluated as electrode materials for CDI, the as-prepared CNT/ACF composites with higher electrical conductivity and mesopore ratios exhibited higher electrosorption capacity and good regeneration performance in comparison with the pure ACF. PMID:25595622

  5. Experimental Comparison of two Active Vibration Control Approaches: Velocity Feedback and Negative Capacitance Shunt Damping

    Beck, Benjamin; Schiller, Noah

    2013-01-01

    This paper outlines a direct, experimental comparison between two established active vibration control techniques. Active vibration control methods, many of which rely upon piezoelectric patches as actuators and/or sensors, have been widely studied, showing many advantages over passive techniques. However, few direct comparisons between different active vibration control methods have been made to determine the performance benefit of one method over another. For the comparison here, the first control method, velocity feedback, is implemented using four accelerometers that act as sensors along with an analog control circuit which drives a piezoelectric actuator. The second method, negative capacitance shunt damping, consists of a basic analog circuit which utilizes a single piezoelectric patch as both a sensor and actuator. Both of these control methods are implemented individually using the same piezoelectric actuator attached to a clamped Plexiglas window. To assess the performance of each control method, the spatially averaged velocity of the window is compared to an uncontrolled response.

  6. Electronics drivers for high voltage dielectric electro active polymer (DEAP) applications

    Zhang, Zhe; Andersen, Michael A. E.

    2015-04-01

    Dielectric electro active polymer (DEAP) can be used in actuation, sensing and energy harvesting applications, but driving the DEAP based actuators and generators has three main challenges from a power electronics standpoint, i.e. high voltage (around 2.5 kV), nonlinearity, and capacitive behavior. In this paper, electronics divers for heating valves, loud speakers, incremental motors, and energy harvesting are reviewed, studied and developed in accordance with their corresponding specifications. Due to the simplicity and low power capacity (below 10W), the reversible Fly-back converters with both magnetic and piezoelectric transformers are employed for the heating valve and incremental motor application, where only ON/OFF regulation is adopted for energy saving; as for DEAP based energy harvesting, the noisolated Buck/Boost converter is used, due to the system high power capacity (above 100W), but the voltage balancing across the series-connected high voltage IGBTs is a critical issue and accordingly a novel gate driver circuitry is proposed and equipped; due to the requirements of the audio products, such as low distortion and noise, the multi-level Buck converter based Class-D amplifier, because of its high control linearity, is implemented for the loud speaker applications. A synthesis among those converter topologies and control techniques is given; therefore, for those DEAP based applications, their diversity and similarity of electronics drivers, as well as the key technologies employed are analyzed. Therefore a whole picture of how to choose the proper topologies can be revealed. Finally, the design guidelines in order to achieve high efficiency and reliability are discussed.

  7. Impact of starting measurement voltage relative to flat-band voltage position on the capacitance-voltage hysteresis and on the defect characterization of InGaAs/high-k metal-oxide-semiconductor stacks

    Vais, Abhitosh; Franco, Jacopo; Lin, Han-Chung; Collaert, Nadine; Mocuta, Anda; De Meyer, Kristin; Thean, Aaron

    2015-11-01

    In this work, we discuss how the position of the flat band voltage with respect to the starting voltage of the C-V measurement sweep can influence the estimation of the hysteresis in high-k/InGaAs MOS devices. We show that, with the support of experimental data and conceptual oxide defect band calculations, the interpretation and subsequent parameter extraction from flat-band voltage shifts observed in III-V MOS devices is more complex as compared to Si gate stacks. It is demonstrated that such complication arises due to the wider distribution of defect levels in the dielectric band gap in the case of InGaAs/high-k stack as compared to standard Si/SiO2/HfO2 MOS. In particular, for Al2O3 deposited on InGaAs, two wide, partially overlapping oxide defect bands are identified, centered ˜1.5 eV and ˜0.5 eV above and below the channel conduction band, respectively. Such defect levels are expected to affect the device operation and reliability.

  8. Role of titania incorporated on activated carbon cloth for capacitive deionization of NaCl solution.

    Ryoo, Min-Woong; Kim, Jong-Ho; Seo, Gon

    2003-08-15

    Adsorption isotherms of NaCl on activated carbon cloth (ACC) and titania-incorporated activated carbon cloth (Ti-ACC) under an electric field were investigated to deduce the role of titania in capacitive deionization (CDI) of NaCl. Electrosorption of NaCl on the ACC was significantly increased by titania incorporation, whereas its physical adsorption was considerably decreased, resulting in an improved performance of the Ti-ACC as a CDI electrode. Langmuir isotherms based on a localized and fixed amount of adsorption were suitable for the simulation of electrosorption and physical adsorption of ions on the ACC electrodes. The variances of q(m) and b of Langmuir isotherms with electric potential indicate increases in the number of ions per adsorption site and in electrosorption strength of ions by titania incorporation. A cyclic voltammetric study for ion adsorption on ACC electrodes confirms the reversibility between electrosorption and desorption of ions, regardless of titania incorporation. PMID:16256660

  9. A voltage-activated proton current in human cardiac fibroblasts

    A voltage-activated proton current in human cardiac fibroblasts, measured using the whole-cell recording configuration of the patch-clamp technique, is reported. Increasing the pH of the bathing solution shifted the current activation threshold to more negative potentials and increased both the current amplitude and its rate of activation. Changing the pH gradient by one unit caused a 51 mV shift in the reversal potential of the current, demonstrating a high selectivity for protons of the channel carrying the current. Extracellularly applied Zn2+ reversibly inhibited the current. Activation of the current contributes to the resting membrane conductance under conditions of intracellular acidosis. It is proposed that this current in cardiac fibroblasts is involved in the regulation of the intracellular pH and the membrane potential under physiological conditions as well as in response to pathological conditions such as ischemia

  10. Steerable Capacitive Proximity Sensor

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Steerable capacitive proximity sensor of "capaciflector" type based partly on sensing units described in GSC-13377 and GSC-13475. Position of maximum sensitivity adjusted without moving sensor. Voltage of each driven shield adjusted separately to concentrate sensing electric field more toward one side or other.

  11. Enhancement of the carbon electrode capacitance by brominated hydroquinones

    Gastol, Dominika; Walkowiak, Jedrzej; Fic, Krzysztof; Frackowiak, Elzbieta

    2016-09-01

    This paper presents supercapacitors utilizing new redox-active electrolytes with bromine species. Two sources of Br specimen were investigated, i.e. dibromodihydroxybenzene dissolved in KOH and potassium bromide dissolved in KOH with hydroxybenzene additive. KOH-activated carbon, exhibiting a well-developed porosity, was incorporated as an electrode material. The tested systems revealed a capacitance enhancement explained by Br- and partial BrO3- redox activity. The optimisation of the electrolyte concentration resulted in a capacitance value of 314 F g-1 achieved at 1.1 V voltage range. Good cyclability performance (11% capacitance loss) combined with a high capacitance value (244 F g-1) were obtained for the system operating in 0.2 mol L- 1 C6H4Br2O2 in 2 mol L-1 KOH electrolytic solution.

  12. Improvement in capacitive deionization function of activated carbon cloth by titania modification.

    Ryoo, Min-Woong; Seo, Gon

    2003-04-01

    Activated carbon cloth (ACC) was modified by the reaction between polar groups on its surface and metal alkoxides of titanium, silicon, aluminum and zirconium to enhance its capacitive deionization (CDI) performance. Incorporated state of metals and surface property of modified ACC were deduced from surface analysis results obtained using FE-SEM, XRD, XPS and zeta-potential meter. Titania was highly dispersed on the ACC surface with tetrahedral coordination, and the incorporated titania was effective to decrease physical adsorption of NaCl and to increase electric field adsorption, resulting in a significant enhancement of CDI performance. The negligible contribution of silica, alumina and zirconia modifications suggested that the small oxidation-reduction potential of titania was responsible for the enhancement of the electric field adsorption. Reversibility of adsorption and desorption operation on titania-modified ACC were also discussed relating to its CDI function. PMID:12600380

  13. Micropower non-contact EEG electrode with active common-mode noise suppression and input capacitance cancellation.

    Chi, Yu M; Cauwenberghs, Gert

    2009-01-01

    A non-contact EEG electrode with input capacitance neutralization and common-mode noise suppression circuits is presented. The coin sized sensor capacitively couples to the scalp without direct contact to the skin. To minimize the effect of signal attenuation and channel gain mismatch, the input capacitance of each sensor is actively neutralized using positive feedback and bootstrapping. Common-mode suppression is achieved through a single conductive sheet to establish a common mode reference. Each sensor electrode provides a differential gain of 60 dB. Signals are transmitted in a digital serial daisy-chain directly from a local 16-bit ADC, minimizing the number of wires required to establish a high density EEG sensor network. The micropower electrode consumes only 600 microW from a single 3.3 V supply. PMID:19964104

  14. SOGI-based capacitor voltage feedback active damping in LCL-filtered grid converters

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang;

    2015-01-01

    The capacitor voltage feedback active damping control is an attractive way to suppress LCL-filter resonance especially for the systems where the capacitor voltage is used for grid synchronization, since no extra sensors are added. The derivative is the core of the capacitor voltage feedback active...... derivative is more suited for capacitor voltage feedback active damping control. Experimental results validate the effectiveness of the proposed method....

  15. Calculation Analysis on Capacitance Compensation in Low-voltage Distribution Design%低压配电设计中电容补偿容量计算分析

    蓝娟

    2012-01-01

    In capacitance compensation design for low-voltage distribution system, to suppress the switching inrush current and harmonic current in capacitor circuit, a reactor is usually connected in series in capacitor circuit; the inductive reactance of the reactor will partially offset the capacitive reactance of capacitor, which will affect the effective compensation of capacitor. Therefore, in calculation of reactive compensation capacity, correction shall be done according to operating voltage of system, reactance rate and rated voltage of capacitor.%低压配电系统电容补偿设计中.为了抑制电容器回路合闸涌流和谐波电流.通常在电容器回路中串接电抗器;串入的电抗器自身的感抗会抵消电容器的部分容抗,对电容器的有效补偿量产生影响。因而,在进行无功补偿容量的计算时,要根据系统运行电压、电抗率的选择,以及电容器额定电压进行修正计算。

  16. On device design for steep-slope negative-capacitance field-effect-transistor operating at sub-0.2V supply voltage with ferroelectric HfO2 thin film

    Kobayashi, Masaharu; Hiramoto, Toshiro

    2016-02-01

    Internet-of-Things (IoT) technologies require a new energy-efficient transistor which operates at ultralow voltage and ultralow power for sensor node devices employing energy-harvesting techniques as power supply. In this paper, a practical device design guideline for low voltage operation of steep-slope negative-capacitance field-effect-transistors (NCFETs) operating at sub-0.2V supply voltage is investigated regarding operation speed, material requirement and energy efficiency in the case of ferroelectric HfO2 gate insulator, which is the material fully compatible to Complementary Metal-Oxide-Semiconductor (CMOS) process technologies. A physics-based numerical simulator was built to design NCFETs with the use of experimental HfO2 material parameters by modeling the ferroelectric gate insulator and FET channel simultaneously. The simulator revealed that NCFETs with ferroelectric HfO2 gate insulator enable hysteresis-free operation by setting appropriate operation point with a few nm thick gate insulator. It also revealed that, if the finite response time of spontaneous polarization of the ferroelectric gate insulator is 10-100psec, 1-10MHz operation speed can be achieved with negligible hysteresis. Finally, by optimizing material parameters and tuning negative capacitance, 2.5 times higher energy efficiency can be achieved by NCFET than by conventional MOSFETs. Thus, NCFET is expected to be a new CMOS technology platform for ultralow power IoT.

  17. On device design for steep-slope negative-capacitance field-effect-transistor operating at sub-0.2V supply voltage with ferroelectric HfO2 thin film

    Masaharu Kobayashi

    2016-02-01

    Full Text Available Internet-of-Things (IoT technologies require a new energy-efficient transistor which operates at ultralow voltage and ultralow power for sensor node devices employing energy-harvesting techniques as power supply. In this paper, a practical device design guideline for low voltage operation of steep-slope negative-capacitance field-effect-transistors (NCFETs operating at sub-0.2V supply voltage is investigated regarding operation speed, material requirement and energy efficiency in the case of ferroelectric HfO2 gate insulator, which is the material fully compatible to Complementary Metal-Oxide-Semiconductor (CMOS process technologies. A physics-based numerical simulator was built to design NCFETs with the use of experimental HfO2 material parameters by modeling the ferroelectric gate insulator and FET channel simultaneously. The simulator revealed that NCFETs with ferroelectric HfO2 gate insulator enable hysteresis-free operation by setting appropriate operation point with a few nm thick gate insulator. It also revealed that, if the finite response time of spontaneous polarization of the ferroelectric gate insulator is 10-100psec, 1-10MHz operation speed can be achieved with negligible hysteresis. Finally, by optimizing material parameters and tuning negative capacitance, 2.5 times higher energy efficiency can be achieved by NCFET than by conventional MOSFETs. Thus, NCFET is expected to be a new CMOS technology platform for ultralow power IoT.

  18. Capacitive desalination of ZnO/activated carbon asymmetric capacitor and mechanism analysis

    ABSTRACT: Zinc oxide/activated carbon composite electrode (ZnO/AC) was prepared by simply mixing ZnO nanoparticles with AC granules in the presence of Teflon emulsion. Scanning electron microscopy shows an even and seamless surface with effective filling of ZnO nanoparticles in between AC granules. Cyclic voltammetry and impedance analysis demonstrate the ideal double-layer capacitor behavior. The desalination behavior of the asymmetric capacitor with ZnO/AC as positive electrode and AC as negative electrode (+ZnO/AC‖AC), or ZnO/AC as negative electrode and AC as positive electrode (−ZnO/AC‖AC) was studied, respectively. As compared with pure AC‖AC capacitor, −ZnO/AC‖AC capacitor showed a very stable desalination behavior with high desalination amount of 9.4 mg/g and charge efficiency of 80.5%; while +ZnO/AC‖AC capacitor showed no obvious difference after several desalination cycles due to poor stability. The mechanism was analyzed based on zeta potential of ZnO particles and pH variation near the electrode surface during charging process. The different desalination properties on positive and negative electrodes due to zeta potential variation of ZnO with pH change at electrode surface were further confirmed by using other metal oxides like CuO, MnO2 and WO3. This study provides a particularly important guidance for screening electrode materials and optimizing operation parameters for capacitive desalination (also called capacitive deionization, CDI)

  19. Employing of Minimum Active Power Injection Strategy to Compensate Voltage Sag by DVR

    A. D. Falehi

    2011-09-01

    Full Text Available In this paper, voltage sag is compensated by the DVR (Dynamic Voltage Restorer in distribution systems. This device is applied between the sensitive load and the supply in order to inject voltage in series to correct the voltage sag. Subsequently, all the other various DVR compensation techniques in the distribution system are explained. Due to the restriction of the energy storage in DVR’s capacitors, it is essential to minimize the active power injected by the DVR. Thus, a minimum active power injection method is proposed to compensate the voltage sag. Performance of this method is evaluated under balanced and unbalance voltage sag in a distribution system.

  20. Effects of pore structure on the high-performance capacitive deionization using chemically activated carbon nanofibers.

    Im, Ji Sun; Kim, Jong Gu; Lee, Young-Seak

    2014-03-01

    Capacitive deionization (CDI) electrodes were constructed from activated carbon fibers prepared using electrospinning and chemical activation. The CDI efficiencies of these electrodes were studied as a function of their specific surface areas, pore volumes and pore sizes via salt ion adsorption. The specific surface areas increased approximately 90 fold and the pore volume also increased approximately 26 fold with the use of greater amounts of the chemical activation agent. There was a relative increase in the mesopore fraction with higher porosity. A NaCI solution was passed through a prepared CDI system, and the salt removal efficiency of the CDI system was determined by the separation of the Na+ and Cl- ions toward the anode and cathode. The CDI efficiency increased with greater specific surface areas and pore volumes. In addition, the efficiency per unit pore volume increased with a reduction in the micropore fraction, resulting in the suppressed overlapping effect. In conclusion, the obtained improvements in CDI efficiency were mainly attributed to mesopores, but the micropores also played an important role in the high-performance CDI under conditions of high applied potential and high ion concentrations. PMID:24745222

  1. Capacitive Proximity Sensor Has Longer Range

    Vranish, John M.

    1992-01-01

    Capacitive proximity sensor on robot arm detects nearby object via capacitive effect of object on frequency of oscillator. Sensing element part of oscillator circuit operating at about 20 kHz. Total capacitance between sensing element and ground constitutes tuning capacitance of oscillator. Sensor circuit includes shield driven by replica of alternating voltage applied to sensing element. Driven shield concentrates sensing electrostatic field in exterior region to enhance sensitivity to object. Sensitivity and dynamic range has corresponding 12-to-1 improvement.

  2. Electrically tunable sign of capacitance in planar W-doped vanadium dioxide micro-switches

    Mohammed Soltani, Mohamed Chaker and Joelle Margot

    2011-01-01

    Negative capacitance (NC) in a planar W-doped VO2 micro-switch was observed at room temperature in the low-frequency range 1 kHz–10 MHz. The capacitance changed from positive to negative values as the W-doped VO2 active layer switched from semiconducting to metallic state under applied voltage. In addition, a capacitance–voltage hysteresis was observed as the applied voltage was cycled from −35 to 35 V. These observations suggest that NC results from the increase of the electrically induced c...

  3. Active gate driver for dv/dt control and active voltage clamping in an IGBT stack

    Rasmussen, Tonny Wederberg

    2005-01-01

    For high voltages converters stacks of IGBTs can be used if the static and dynamic voltage sharing among the IGBTs can be applied. dVCE/dt should also be controlled in order not to damage insulation material. This paper describes theory and measurements of an active gate driver for stacking IGBTs....... For the measurements two series connected standard IGBTs made for hard switching applications are used. Problems are shown and proposals for improvements are given....

  4. Complementary surface charge for enhanced capacitive deionization.

    Gao, X; Porada, S; Omosebi, A; Liu, K-L; Biesheuvel, P M; Landon, J

    2016-04-01

    Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI cell to examine their salt removal at a fixed charging voltage and both reduced and opposite polarity discharge voltages, and subsequently compared to the salt removal of untreated electrodes. Substantially improved salt removal due to chemical surface charge and the use of a discharge voltage of opposite sign to the charging voltage is clearly demonstrated in these CDI cycling tests, an observation which for the first time validates both enhanced CDI and extended-voltage CDI effects predicted by the Donnan model [Biesheuvel et al., Colloids Interf. Sci. Comm., 10.1016/j.colcom.2015.12.001 (2016)]. Our experimental and theoretical results demonstrate that the use of carbon electrodes with optimized chemical surface charge can extend the CDI working voltage window through discharge voltages of opposite sign to the charging voltage, which can significantly enhance the salt adsorption capacity of CDI electrodes. Thus, in addition to carbon pore size distribution, chemical surface charge in carbon micropores is considered foundational for salt removal in CDI cells. PMID:26878361

  5. Oxygen- and nitrogen-co-doped activated carbon from waste particleboard for potential application in high-performance capacitance

    Graphical abstract: All electrodes showed excellent capacitance and retention versus discharge current density from 0.05 to 5 A/g. - Abstract: Oxygen- and nitrogen-co-doped activated carbons were obtained from phosphoric acid treated nitrogen-doped activated carbons which were prepared from waste particleboard bonded with urea-formaldehyde resin adhesives. The activated carbon samples obtained were tested as supercapacitors in two-electrode cell and extensive wetting 7 M KOH electrolytes. Their structural properties and surface chemistry, before the electrical testing, were investigated using elemental analysis, X-ray photoelectron spectroscopy, scanning electron microscopy, X-ray diffraction, Raman spectra, and adsorption of nitrogen. Activated carbon treated by 4 M phosphoric acid of the highest capacitance (235 F/g) was measured in spite of a relatively lower surface (1360 m2/g) than that of the activated carbon treated by 2 M phosphoric acid (1433 m2/g). The surface chemistry, and especially oxygen- and nitrogen-containing functional groups, was found of paramount importance for the capacitive behavior and for the effective pore space utilization by the electrolyte ions

  6. Improved capacitive deionization performance of mixed hydrophobic/hydrophilic activated carbon electrodes

    Capacitive deionization (CDI) is a promising salt removal technology with high energy efficiency when applied to low molar concentration aqueous electrolytes. As an interfacial process, ion electrosorption during CDI operation is sensitive to the pore structure and the total pore volume of carbon electrodes limits the maximum salt adsorption capacity (SAC). Thus, activation of carbons as a widely used method to enhance the porosity of a material should also be highly attractive for improving SAC values. In our study, we use easy-to-scale and facile-to-apply CO2-activation at temperatures between 950 °C and 1020 °C to increase the porosity of commercially available activated carbon. While the pore volume and surface area can be significantly increased up to 1.51 cm3 g−1 and 2113 m2 g−1, this comes at the expense of making the carbon more hydrophobic. We present a novel strategy to capitalize on the improved pore structure by admixing as received (more hydrophilic) carbon with CO2-treated (more hydrophobic) carbon for CDI electrodes without using membranes. This translates into an enhanced charge storage ability in high and low molar concentrations (1 M and 5 mM NaCl) and significantly improved CDI performance (at 5 mM NaCl). In particular, we obtain stable CDI performance at 0.86 charge efficiency with 13.1 mg g−1 SAC for an optimized 2:1 mixture (by mass). (paper)

  7. Improved capacitive deionization performance of mixed hydrophobic/hydrophilic activated carbon electrodes.

    Aslan, M; Zeiger, M; Jäckel, N; Grobelsek, I; Weingarth, D; Presser, V

    2016-03-23

    Capacitive deionization (CDI) is a promising salt removal technology with high energy efficiency when applied to low molar concentration aqueous electrolytes. As an interfacial process, ion electrosorption during CDI operation is sensitive to the pore structure and the total pore volume of carbon electrodes limits the maximum salt adsorption capacity (SAC). Thus, activation of carbons as a widely used method to enhance the porosity of a material should also be highly attractive for improving SAC values. In our study, we use easy-to-scale and facile-to-apply CO2-activation at temperatures between 950 °C and 1020 °C to increase the porosity of commercially available activated carbon. While the pore volume and surface area can be significantly increased up to 1.51 cm(3) g(-1) and 2113 m(2) g(-1), this comes at the expense of making the carbon more hydrophobic. We present a novel strategy to capitalize on the improved pore structure by admixing as received (more hydrophilic) carbon with CO2-treated (more hydrophobic) carbon for CDI electrodes without using membranes. This translates into an enhanced charge storage ability in high and low molar concentrations (1 M and 5 mM NaCl) and significantly improved CDI performance (at 5 mM NaCl). In particular, we obtain stable CDI performance at 0.86 charge efficiency with 13.1 mg g(-1) SAC for an optimized 2:1 mixture (by mass). PMID:26902896

  8. Improved capacitive deionization performance of mixed hydrophobic/hydrophilic activated carbon electrodes

    Aslan, M.; Zeiger, M.; Jäckel, N.; Grobelsek, I.; Weingarth, D.; Presser, V.

    2016-03-01

    Capacitive deionization (CDI) is a promising salt removal technology with high energy efficiency when applied to low molar concentration aqueous electrolytes. As an interfacial process, ion electrosorption during CDI operation is sensitive to the pore structure and the total pore volume of carbon electrodes limits the maximum salt adsorption capacity (SAC). Thus, activation of carbons as a widely used method to enhance the porosity of a material should also be highly attractive for improving SAC values. In our study, we use easy-to-scale and facile-to-apply CO2-activation at temperatures between 950 °C and 1020 °C to increase the porosity of commercially available activated carbon. While the pore volume and surface area can be significantly increased up to 1.51 cm3 g-1 and 2113 m2 g-1, this comes at the expense of making the carbon more hydrophobic. We present a novel strategy to capitalize on the improved pore structure by admixing as received (more hydrophilic) carbon with CO2-treated (more hydrophobic) carbon for CDI electrodes without using membranes. This translates into an enhanced charge storage ability in high and low molar concentrations (1 M and 5 mM NaCl) and significantly improved CDI performance (at 5 mM NaCl). In particular, we obtain stable CDI performance at 0.86 charge efficiency with 13.1 mg g-1 SAC for an optimized 2:1 mixture (by mass).

  9. Dielectric Electro Active Polymer Incremental Actuator Driven by Multiple High-Voltage Bi-directional DC-DC Converters

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.;

    2013-01-01

    capacitive sub-actuators. It needs to be driven by three high voltage (~2.5 kV) DC-DC converters, to achieve the linear incremental motion. The topology used for this application is a bi-directional flyback DC-DC converter. The control of the incremental actuator involves, implementation of digital...

  10. Voltage Estimation in Active Distribution Grids Using Neural Networks

    Pertl, Michael; Heussen, Kai; Gehrke, Oliver;

    2016-01-01

    observability of distribution systems has to be improved. To increase the situational awareness of the power system operator data driven methods can be employed. These methods benefit from newly available data sources such as smart meters. This paper presents a voltage estimation method based on neural networks......The power flow in distribution grids is becoming more complicated as reverse power flows and undesired voltage rises might occur under particular circumstances due to integration of renewable energy sources, increasing the occurrence of critical bus voltages. To identify these critical feeders the...

  11. Profiles for voltage-activated currents are multiphasic, not curvilinear

    Nissen, Per

    2016-01-01

    Data for voltage-activation of a potassium channel (Matulef et al. Proc Natl Acad Sci USA 110: 17886-17891. 2013) were, as conventionally done, fitted by the authors by a Boltzmann function, i.e. by a curvilinear profile. Reanalysis of the data reveals however that this interpretation must be rejected in favor of a multiphasic profile, a series of straight lines separated by discontinuous transitions, quite often in the form of noncontiguities (jumps). In contrast to the generally very poor fits to the Boltzmann profiles, the fits to multiphasic profiles are very good. (For the four replicates, the average deviations from the Boltzmann curves were 10- to 100-fold larger than the deviations from the multiphasic profiles.) The difference in the median values was statistically highly significant, P<0.001 in most cases. For the mean values the deviations from the Boltzmann curve were 20-fold larger than the deviations from the multiphasic profile, and the difference in the median values was also highly signifi...

  12. Modulation of Neuronal Voltage-Activated Calcium and Sodium Channels by Polyamines and pH

    Chen, Wenyan; Harnett, Mark T.; Smith, Stephen M.

    2007-01-01

    The endogenous polyamines spermine, spermidine and putrescine are present at high concentrations inside neurons and can be released into the extracellular space where they have been shown to modulate ion channels. Here, we have examined polyamine modulation of voltage-activated Ca2+ channels (VACCs) and voltage-activated Na+ channels (VANCs) in rat superior cervical ganglion neurons using whole-cell voltage-clamp at physiological divalent concentrations. Polyamines inhibited VACCs in a concen...

  13. Voltage Quality Enhancement and Fault Current Limiting with Z-Source based Series Active Filter

    F. Gharedaghi

    2011-11-01

    Full Text Available In this study, series active filter or dynamic voltage restorer application is proposed for reduction of downstream fault current in addition to voltage quality enhancement. Recently, the application of Z-source inverter is proposed in order to optimize DVR operation. This inverter makes DVR to operate appropriately when the energy storage device’s voltage level severely falls. Here, the Z-source inverter based DVR is proposed to compensate voltage disturbance at the PCC and to reduce the fault current in downstream of DVR. By calculating instantaneous current magnitude in synchronous frame, control system recognizes if the fault exists or not, and determines whether DVR should compensate voltage disturbance or try to reduce the fault current. The proposed system is simulated under voltage sag and swell and short circuit conditions. The simulation results show that the system operates correctly under voltage sag and short circuit conditions.

  14. Experimental determination of dielectric barrier discharge capacitance.

    Pipa, A V; Hoder, T; Koskulics, J; Schmidt, M; Brandenburg, R

    2012-07-01

    The determination of electrical parameters (such as instantaneous power, transferred charge, and gas gap voltage) in dielectric barrier discharge (DBD) reactors relies on estimates of key capacitance values. In the classic large-scale sinusoidal-voltage driven DBD, also known as silent or ozonizer discharge, capacitance values can be determined from charge-voltage (Q-V) plot, also called Lissajous figure. For miniature laboratory reactors driven by fast pulsed voltage waveforms with sub-microsecond rise time, the capacitance of the dielectric barriers cannot be evaluated from a single Q-V plot because of the limited applicability of the classical theory. Theoretical determination can be problematic due to electrode edge effects, especially in the case of asymmetrical electrodes. The lack of reliable capacitance estimates leads to a "capacitance bottleneck" that obstructs the determination of other DBD electrical parameters in fast-pulsed reactors. It is suggested to obtain capacitance of dielectric barriers from a plot of the maximal charge versus maximal voltage amplitude (Q(max) - V(max) plot) in a manner analogous to the classical approach. The method is examined using measurements of current and voltage waveforms of a coaxial DBD reactor in argon at 100 mbar driven by square voltage pulses with a rise time of 20 ns and with different voltage amplitudes up to 10 kV. Additionally, the applicability of the method has been shown for the data reported in literature measured at 1 bar of nitrogen-oxygen gas mixtures and xenon. PMID:22852728

  15. Phase-Discriminating Capacitive Sensor System

    Vranish, John M.; Rahim, Wadi

    1993-01-01

    Crosstalk eliminated by maintaining voltages on all electrodes at same amplitude, phase, and frequency. Each output feedback-derived control voltage, change of which indicates proximity-induced change in capacitance of associated sensing electrode. Sensors placed close together, enabling imaging of sort. Images and/or output voltages used to guide robots in proximity to various objects.

  16. Fast and slow activation kinetics of voltage-gated sodium channels in molluscan neurons.

    Gilly, W F; Gillette, R; McFarlane, M

    1997-05-01

    Whole cell patch-clamp recordings of Na current (I(Na)) were made under identical experimental conditions from isolated neurons from cephalopod (Loligo, Octopus) and gastropod (Aplysia, Pleurobranchaea, Doriopsilla) species to compare properties of activation gating. Voltage dependence of peak Na conductance (gNa) is very similar in all cases, but activation kinetics in the gastropod neurons studied are markedly slower. Kinetic differences are very pronounced only over the voltage range spanned by the gNa-voltage relation. At positive and negative extremes of voltage, activation and deactivation kinetics of I(Na) are practically indistinguishable in all species studied. Voltage-dependent rate constants underlying activation of the slow type of Na channel found in gastropods thus appear to be much more voltage dependent than are the equivalent rates in the universally fast type of channel that predominates in cephalopods. Voltage dependence of inactivation kinetics shows a similar pattern and is representative of activation kinetics for the two types of Na channels. Neurons with fast Na channels can thus make much more rapid adjustments in the number of open Na channels at physiologically relevant voltages than would be possible with only slow Na channels. This capability appears to be an adaptation that is highly evolved in cephalopods, which are well known for their high-speed swimming behaviors. Similarities in slow and fast Na channel subtypes in molluscan and mammalian neurons are discussed. PMID:9163364

  17. Molecular Interactions between Tarantula Toxins and Low-Voltage-Activated Calcium Channels

    Autoosa Salari; Benjamin S. Vega; Milescu, Lorin S.; Mirela Milescu

    2016-01-01

    Few gating-modifier toxins have been reported to target low-voltage-activated (LVA) calcium channels, and the structural basis of toxin sensitivity remains incompletely understood. Studies of voltage-gated potassium (Kv) channels have identified the S3b–S4 “paddle motif,” which moves at the protein-lipid interface to drive channel opening, as the target for these amphipathic neurotoxins. Voltage-gated calcium (Cav) channels contain four homologous voltage sensor domains, suggesting multiple t...

  18. Capacitor Current Feedback-Based Active Resonance Damping Strategies for Digitally-Controlled Inductive-Capacitive-Inductive-Filtered Grid-Connected Inverters

    Iman Lorzadeh

    2016-08-01

    Full Text Available Inductive-capacitive-inductive (LCL-type line filters are widely used in grid-connected voltage source inverters (VSIs, since they can provide substantially improved attenuation of switching harmonics in currents injected into the grid with lower cost, weight and power losses than their L-type counterparts. However, the inclusion of third order LCL network complicates the current control design regarding the system stability issues because of an inherent resonance peak which appears in the open-loop transfer function of the inverter control system near the control stability boundary. To avoid passive (resistive resonance damping solutions, due to their additional power losses, active damping (AD techniques are often applied with proper control algorithms in order to damp the LCL filter resonance and stabilize the system. Among these techniques, the capacitor current feedback (CCF AD has attracted considerable attention due to its effective damping performance and simple implementation. This paper thus presents a state-of-the-art review of resonance and stability characteristics of CCF-based AD approaches for a digitally-controlled LCL filter-based grid-connected inverter taking into account the effect of computation and pulse width modulation (PWM delays along with a detailed analysis on proper design and implementation.

  19. Digital Realization of Capacitor-Voltage Feedback Active Damping for LCL-Filtered Grid Converters

    Xin, Zhen; Wang, Xiongfei; Loh, Poh Chiang;

    2015-01-01

    The capacitor voltage of an LCL-filter can also be used for active damping, if it is fed back for synchronization. By this way, an extra current sensor can be avoided. Compared with the existing active damping techniques designed with capacitor current feedback, the capacitor voltage feedback...... overcome their drawbacks, a new derivative method is then proposed, based on the non-ideal generalized integrator. The performance of the proposed derivative has been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately, as...

  20. Driven shielding capacitive proximity sensor

    Vranish, John M. (Inventor); McConnell, Robert L. (Inventor)

    2000-01-01

    A capacitive proximity sensing element, backed by a reflector driven at the same voltage as and in phase with the sensor, is used to reflect the field lines away from a grounded robot arm towards an intruding object, thus dramatically increasing the sensor's range and sensitivity.

  1. High Efficiency Interleaved Active Clamped Dc-Dc Converter with Fuel Cell for High Voltage Applications

    Sona P

    2014-02-01

    Full Text Available A high efficiency interleaved ZVS active clamped current fed dc-dc converter is proposed in this paper specially used for fuel cell applications. As the fuel cell output is very low we are in need of a step up dc-dc converter. Here a current fed dc-dc converter is used. Two current fed dc-dc converters are interleaved by connecting their inputs in parallel and outputs in series. With this proposed methodology input current ripples in the fuel cell stacks can be reduced and a regulated output voltage ripples can be obtained. The active clamping circuit used in this model absorbs the turn off voltage spikes hence low voltage devices with low on state resistance can be used.Voltage doubler circuits will give double the output voltage than normal with smaller transformer turns ratio and flexibility. The proposed method is simulated in MATLAB for verifying the accuracy of the proposed design.

  2. Enhancing the capacitances of electric double layer capacitors based on carbon nanotube electrodes by carbon dioxide activation and acid oxidization

    2010-01-01

    Polarizable electrodes of electric double layer capacitors(EDLCs) were made from carbon nanotubes(CNTs).Effect of carbon dioxide activation together with acid oxidation for the electrodes on the characteristics and performances of electrodes and EDLCs was studied.Carbon dioxide activation changed the microstructure of the electrodes,increased the effective surface area of CNTs and optimized the distribution of apertures of the electrodes.Acid oxidization modified the surface characteristics of CNTs.Based on the polarizable electrodes treated by carbon dioxide activation and acid oxidization,the performances of EDLCs were greatly enhanced.The specific capacitance of the electrodes with organic electrolyte was increased from 21.8 F/g to 60.4 F/g.

  3. 煤矿低压电网漏电容性电流自动补偿研究%Research on Capacitive Current Automatic Compensation on Low Voltage Power Grid Leakage Protection of Coal Mine

    徐国萍

    2014-01-01

    In neutral insulation low voltage power supply lines of coal mine,due to distributed capacitance exists, the leakage currents or personal electric shock currents exceed the limited safety value, and the changes of distributed capacitance easily cause the original system overcompensation or under compensation. The automatic compensation scheme of combining inductance the coarse adjustment with the fine adjustment is proposed on base of the minimum leakage currents closed loop control theory. Using single chip microcomputer control relay automatic switching magnetic amplifier is to achieve multi tap AC winding inductance step adjustment. The currents of magnetic amplifier DC winding are changed by single chip microcomputer control step motor to adjust potentiometer. The system attains stepless regulation of the inductance, so that the currents of distributed capacitance are completely compensated by the inductor currents of the magnetic amplifier. It has many advantages of fast compensation speed, high precision, short cycle, safety and easy operation during compensation process.%针对煤矿井下中性点绝缘低压供电线路中,由于电网对地分布电容的存在,使漏电电流或人身触电电流超过极限安全值,并且电网分布电容的多变容易引起原系统过补偿或欠补偿的情况,提出基于最小漏电电流闭环控制理论的电感量粗调和细调相融合的自动补偿方案,采用单片机控制继电器自动切换磁放大器多抽头交流绕组实现电感量有级调节,通过步进电机调节电位器改变磁放大器直流绕组的电流,实现电感量无级调节,从而使流过磁放大器的电感电流完全补偿电网分布电容的电流。该系统补偿速度快、精度高、调整周期短,补偿过程操作方便、安全。

  4. Highly Accurate Derivatives for LCL-Filtered Grid Converter with Capacitor Voltage Active Damping

    Xin, Zhen; Loh, Poh Chiang; Wang, Xiongfei;

    2016-01-01

    The middle capacitor voltage of an LCL-filter, if fed back for synchronization, can be used for active damping. An extra sensor for measuring the capacitor current is then avoided. Relating the capacitor voltage to existing popular damping techniques designed with capacitor current feedback would...... then proposed, based on either second-order or non-ideal generalized integrator. Performances of these derivatives have been found to match the ideal “s” function closely. Active damping based on capacitor voltage feedback can therefore be realized accurately. Experimental results presented have...

  5. Advanced Control Strategy for Single-Phase Voltage-Source Active Rectifier with Low Harmonic Emission

    Blahník, Vojtĕch; Peroutka, Zdenĕk; Talla, Jakub

    2014-03-01

    This paper introduces the advanced control of single-phase voltage-source active rectifier. This control provide direct control of trolley-wire current and active damping of low-frequency disturbances at the converter ac side. Our proposed control strategy combines PR controller with feed-forward model and low-frequency harmonic compensator based on resonant controllers. Achieved experimental results show excellent converter behavior, where converter is fed by strongly distorted supply voltage.

  6. Parallel input parallel output high voltage bi-directional converters for driving dielectric electro active polymer actuators

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.;

    2014-01-01

    Dielectric electroactive polymer (DEAP) actuators are capacitive devices which provide mechanical motions when charged electrically. The charging characteristics of a DEAP actuator depends on its size, voltage applied to its electrodes, and its operating frequency. The main idea of this paper is to......-DC converter incorporating commercially available high voltage MOSFETs (4 kV) and high voltage diodes (5 kV). Although the average current of the aforementioned devices is limited to 300 mA and 150 mA, respectively, connecting the outputs of multiple converters in parallel can provide a scalable design. This...... enables operating the DEAP actuators in various static and dynamic applications e.g. positioning, vibration generation or damping, and pumps. The proposed idea is experimentally verified by connecting three high voltage converters in parallel to operate a single DEAP actuator. The experimental results...

  7. Capacitive Extensometer

    Perusek, Gail P. (Inventor)

    2003-01-01

    The present invention provides for measurements of the principal strain magnitudes and directions, and maximum shear strain that occurs in a porous specimen, such as plastic, ceramic or porous metal, when it is loaded (or subjected to a load). In one embodiment the invention includes a capacitive delta extensometer arranged with six sensors in a three piece configuration, with each sensor of each pair spaced apart from each other by a predetermined angle, such as 120 degrees.

  8. Magnetization-induced double-layer capacitance enhancement in active carbon/Fe3O4 nanocomposites

    Guoxiang Wang; Hongfeng Xu; Lu Lu; Hong Zhao

    2014-01-01

    The effects of magnetic fields on electrochemical processes have made a great impact on both theoretical and practical significances in im-proving capacitor performance. In this study, active carbon/Fe3O4-NPs nanocomposites (AC/Fe3O4-NPs) were synthesized using a facile hy-drothermal method and ultrasonic technique. Transmission electron micrographs (TEM) showed that Fe3O4 nanoparticles (Fe3O4-NPs) grew along the edge of AC. AC/Fe3O4-NPs nanocomposites were further used as an electrochemical electrode, and its electrochemical performance was tested under magnetization and non-magnetization conditions, respectively, in a three-electrode electrochemical device. Micro-magnetic field could improve the electric double-layer capacitance, reduce the charge transfer resistance, and enhance the discharge performance. The capacitance enhancement of magnetized electrode was increased by 33.1%at the current density of 1 A/g, and the energy density was improved to 15.97 Wh/kg, due to the addition of magnetic particles.

  9. Astaxanthin Improves Human Sperm Capacitation by Inducing Lyn Displacement and Activation.

    Andrisani, Alessandra; Donà, Gabriella; Tibaldi, Elena; Brunati, Anna Maria; Sabbadin, Chiara; Armanini, Decio; Alvisi, Gualtiero; Gizzo, Salvatore; Ambrosini, Guido; Ragazzi, Eugenio; Bordin, Luciana

    2015-09-01

    Astaxanthin (Asta), a photo-protective red pigment of the carotenoid family, is known for its multiple beneficial properties. In this study, the effects of Asta on isolated human sperm were evaluated. Capacitation involves a series of transformations to let sperm acquire the correct features for potential oocyte fertilization, including the generation of a controlled amount of reactive oxygen species (ROS), cholesterol depletion of the sperm outer membrane, and protein tyrosine phosphorylation (Tyr-P) process in the head region. Volunteers, with normal spermiogram values, were divided in two separate groups on the basis of their ability to generate the correct content of endogenous ROS. Both patient group (PG) and control group (CG) were analysed for Tyr-phosphorylation (Tyr-P) pattern and percentages of acrosome-reacted cells (ARC) and non-viable cells (NVC), in the presence or absence of Asta. In addition, the involvement of ROS on membrane reorganization and the presence of Lyn, a Src family kinase associated with lipid rafts, were investigated. Results show that Lyn is present in the membranes of human sperm, mainly confined in midpiece in resting conditions. Following capacitation, Lyn translocated to the head concomitantly with raft relocation, thus allowing the Tyr-P of head proteins. Asta succeeded to trigger Lyn translocation in PG sperm thus bypassing the impaired ROS-related mechanism for rafts and Lyn translocation. In this study, we showed an interdependence between ROS generation and lipid rafts and Lyn relocation leading the cells to undergo the successive acrosome reaction (AR). Asta, by ameliorating PG sperm functioning, may be utilised to decrease male idiopathic infertility. PMID:26308013

  10. Astaxanthin Improves Human Sperm Capacitation by Inducing Lyn Displacement and Activation

    Alessandra Andrisani

    2015-08-01

    Full Text Available Astaxanthin (Asta, a photo-protective red pigment of the carotenoid family, is known for its multiple beneficial properties. In this study, the effects of Asta on isolated human sperm were evaluated. Capacitation involves a series of transformations to let sperm acquire the correct features for potential oocyte fertilization, including the generation of a controlled amount of reactive oxygen species (ROS, cholesterol depletion of the sperm outer membrane, and protein tyrosine phosphorylation (Tyr-P process in the head region. Volunteers, with normal spermiogram values, were divided in two separate groups on the basis of their ability to generate the correct content of endogenous ROS. Both patient group (PG and control group (CG were analysed for Tyr-phosphorylation (Tyr-P pattern and percentages of acrosome-reacted cells (ARC and non-viable cells (NVC, in the presence or absence of Asta. In addition, the involvement of ROS on membrane reorganization and the presence of Lyn, a Src family kinase associated with lipid rafts, were investigated. Results show that Lyn is present in the membranes of human sperm, mainly confined in midpiece in resting conditions. Following capacitation, Lyn translocated to the head concomitantly with raft relocation, thus allowing the Tyr-P of head proteins. Asta succeeded to trigger Lyn translocation in PG sperm thus bypassing the impaired ROS-related mechanism for rafts and Lyn translocation. In this study, we showed an interdependence between ROS generation and lipid rafts and Lyn relocation leading the cells to undergo the successive acrosome reaction (AR. Asta, by ameliorating PG sperm functioning, may be utilised to decrease male idiopathic infertility.

  11. Electrical capacitance clearanceometer

    Hester, Norbert J. (Inventor); Hornbeck, Charles E. (Inventor); Young, Joseph C. (Inventor)

    1992-01-01

    A hot gas turbine engine capacitive probe clearanceometer is employed to measure the clearance gap or distance between blade tips on a rotor wheel and its confining casing under operating conditions. A braze sealed tip of the probe carries a capacitor electrode which is electrically connected to an electrical inductor within the probe which is inserted into a turbine casing to position its electrode at the inner surface of the casing. Electrical power is supplied through a voltage controlled variable frequency oscillator having a tuned circuit in which the probe is a component. The oscillator signal is modulated by a change in electrical capacitance between the probe electrode and a passing blade tip surface while an automatic feedback correction circuit corrects oscillator signal drift. A change in distance between a blade tip and the probe electrode is a change in capacitance therebetween which frequency modulates the oscillator signal. The modulated oscillator signal which is then processed through a phase detector and related circuitry to provide an electrical signal is proportional to the clearance gap.

  12. Bactericidal activity of high voltage pulsed current (HVPC in vitro

    Kramer, Axel

    2006-08-01

    Full Text Available The positive effect of electrical stimulation (ES on wound healing has been shown in vitro and in vivo. Based on increased blood flow, protein denaturation and stimulation of cellular defence, an antibacterial effect of ES is to be expected. Although the antibacterial effect of ES already has been demonstrated in vitro, little attention has been paid to the direct antibacterial effect of changing polarity of the applied current. The aim of this study was to investigate the antibacterial effect of positive and negative monophasic high voltage pulsed current (HVPV on typical gram positive and gram negative pathogens of chronic wounds.Using the WoundEL®-System, three gram negative (E. coli, P. aeruginosa, K. pneumoniae and three gram positive (S. aureus, S. epidermidis, E. faecium organisms were tested against positive and negative polarity HVPV. All tested organisms were significantly (P < 0.01 reduced by ES. The reduction differed significantly (P = 0.02 between positive and negative polarity, with the highest log10 RF achieved with positive polarity. Using positive polarity, the maximum RF was measured for Escherichia coli (median log10 RF 0.83; 25th percentile 0.59, 75th percentile 0.98, the lowest for Staphylococcus epidermidis (median log10 RF 0.20; 25th percentile 0.17, 75th percentile 0.24. Yet, there was no significant difference with positive ES against gram positive (P = 0.35 or gram negative (P = 0.71 organisms.

  13. Operation of Active Front-End Rectifier in Electric Drive under Unbalanced Voltage Supply

    Chomát, Miroslav

    Rijeka: INTECHWEB.ORG, 2011 - (Chomát, M.), s. 195-216 ISBN 978-953-307-548-8 R&D Projects: GA ČR GA102/09/1273 Institutional research plan: CEZ:AV0Z20570509 Keywords : unbalanced voltage supply * DC-link voltage pulsations * pulse-width modulation Subject RIV: JA - Electronic s ; Optoelectronics, Electrical Engineering http://www.intechopen.com/books/electric-machines- and -drives/operation-of-active-front-end-rectifier-in-electric-drive-under-unbalanced-voltage-supply

  14. Fabrication and characterization of a tethered rotational planar variable capacitance micro drive

    In this paper, we present the design, fabrication and characterization of a planar variable capacitance micro drive. The rotational micro drive is developed for high-speed applications with contactless active electrostatic micro bearings. The associated low-temperature process allows the fabrication of devices with narrow stator–rotor gaps. The drive performance is characterized by means of tethered functional prototype devices. The multicompliant devices have silicon rotors and a soft polymer suspension, which allows the validated modeling of the drive capacitance and accurate measurement of the static drive torques. The devices achieve up to 2.6 nNm static drive torque per phase at an actuation voltage of 12 V. These results demonstrate the highest torque generation of a planar variable capacitance drive at low actuation voltages. (paper)

  15. Interneuron Activity Leads to Initiation of Low-Voltage Fast-Onset Seizures

    Shiri, Zahra; Manseau, Frédéric; Lévesque, Maxime; Williams, Sylvain; Avoli, Massimo

    2016-01-01

    Seizures in temporal lobe epilepsy can be classified as hypersynchronous and low-voltage fast according to their onset patterns. Experimental evidence suggests that low-voltage fast-onset seizures mainly result from the synchronous activity of γ-aminobutyric acid–releasing cells. In this study, we tested this hypothesis using the optogenetic control of parvalbumin-positive interneurons in the entorhinal cortex, in the in vitro 4-aminopyridine model. We found that both spontaneous and optogenetically induced seizures had similar low-voltage fast-onset patterns. In addition, both types of seizures presented with higher ripple than fast ripple rates. Our data demonstrate the involvement of interneuronal networks in the initiation of low-voltage fast-onset seizures. PMID:25546300

  16. New active load voltage clamp for HF-link converters

    Ljusev, Petar; Andersen, Michael Andreas E.

    2005-01-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path...

  17. An approach to evaluate capacitance, capacitive reactance and resistance of pivoted pads of a thrust bearing

    Prashad, Har

    1992-07-01

    A theoretical approach is developed for determining the capacitance and active resistance between the interacting surfaces of pivoted pads and thrust collar, under different conditions of operation. It is shown that resistance and capacitive reactance of a thrust bearing decrease with the number of pads times the values of these parameters for an individual pad, and that capacitance increases with the number of pads times the capacitance of an individual pad. The analysis presented has a potential to diagnose the behavior of pivoted pad thrust bearings with the angle of tilt and the ratio of film thickness at the leading to trailing edge, by determining the variation of capacitance, resistance, and capacitive reactance.

  18. Electrically tunable sign of capacitance in planar W-doped vanadium dioxide micro-switches

    Mohammed Soltani, Mohamed Chaker and Joelle Margot

    2011-01-01

    Full Text Available Negative capacitance (NC in a planar W-doped VO2 micro-switch was observed at room temperature in the low-frequency range 1 kHz–10 MHz. The capacitance changed from positive to negative values as the W-doped VO2 active layer switched from semiconducting to metallic state under applied voltage. In addition, a capacitance–voltage hysteresis was observed as the applied voltage was cycled from −35 to 35 V. These observations suggest that NC results from the increase of the electrically induced conductivity in the active layer. This NC phenomenon could be exploited in advanced multifunctional devices including ultrafast switches, field-effect transistors and memcapacitive systems.

  19. New active load voltage clamp for HF-link converters

    Ljusev, P.; Andersen, M.A.E.

    2005-07-01

    This paper proposes a new active clamp for HF-link converters, which features very high efficiency by returning the clamped energy back to the primary side through a small auxiliary converter. It also increases the reliability of HF-link converters by providing an alternative load current path during malfunctions of the secondary bidirectional bridge. The feasibility of the approach is shown on audio power amplifier prototype. New integrated magnetics design is presented that incorporates both the main power and auxiliary transformer on the same magnetic core. (au)

  20. Chemoselective tarantula toxins report voltage activation of wild-type ion channels in live cells.

    Tilley, Drew C; Eum, Kenneth S; Fletcher-Taylor, Sebastian; Austin, Daniel C; Dupré, Christophe; Patrón, Lilian A; Garcia, Rita L; Lam, Kit; Yarov-Yarovoy, Vladimir; Cohen, Bruce E; Sack, Jon T

    2014-11-01

    Electrically excitable cells, such as neurons, exhibit tremendous diversity in their firing patterns, a consequence of the complex collection of ion channels present in any specific cell. Although numerous methods are capable of measuring cellular electrical signals, understanding which types of ion channels give rise to these signals remains a significant challenge. Here, we describe exogenous probes which use a novel mechanism to report activity of voltage-gated channels. We have synthesized chemoselective derivatives of the tarantula toxin guangxitoxin-1E (GxTX), an inhibitory cystine knot peptide that binds selectively to Kv2-type voltage gated potassium channels. We find that voltage activation of Kv2.1 channels triggers GxTX dissociation, and thus GxTX binding dynamically marks Kv2 activation. We identify GxTX residues that can be replaced by thiol- or alkyne-bearing amino acids, without disrupting toxin folding or activity, and chemoselectively ligate fluorophores or affinity probes to these sites. We find that GxTX-fluorophore conjugates colocalize with Kv2.1 clusters in live cells and are released from channels activated by voltage stimuli. Kv2.1 activation can be detected with concentrations of probe that have a trivial impact on cellular currents. Chemoselective GxTX mutants conjugated to dendrimeric beads likewise bind live cells expressing Kv2.1, and the beads are released by channel activation. These optical sensors of conformational change are prototype probes that can indicate when ion channels contribute to electrical signaling. PMID:25331865

  1. GABAB receptors inhibit low-voltage activated and high-voltage activated Ca(2+) channels in sensory neurons via distinct mechanisms.

    Huang, Dongyang; Huang, Sha; Peers, Chris; Du, Xiaona; Zhang, Hailin; Gamper, Nikita

    2015-09-18

    Growing evidence suggests that mammalian peripheral somatosensory neurons express functional receptors for gamma-aminobutyric acid, GABAA and GABAB. Moreover, local release of GABA by pain-sensing (nociceptive) nerve fibres has also been suggested. Yet, the functional significance of GABA receptor triggering in nociceptive neurons is not fully understood. Here we used patch-clamp recordings from small-diameter cultured DRG neurons to investigate effects of GABAB receptor agonist baclofen on voltage-gated Ca(2+) currents. We found that baclofen inhibited both low-voltage activated (LVA, T-type) and high-voltage activated (HVA) Ca(2+) currents in a proportion of DRG neurons by 22% and 32% respectively; both effects were sensitive to Gi/o inhibitor pertussis toxin. Inhibitory effect of baclofen on both current types was about twice less efficacious as compared to that of the μ-opioid receptor agonist DAMGO. Surprisingly, only HVA but not LVA current modulation by baclofen was partially prevented by G protein inhibitor GDP-β-S. In contrast, only LVA but not HVA current modulation was reversed by the application of a reducing agent dithiothreitol (DTT). Inhibition of T-type Ca(2+) current by baclofen and the recovery of such inhibition by DTT were successfully reconstituted in the expression system. Our data suggest that inhibition of LVA current in DRG neurons by baclofen is partially mediated by an unconventional signaling pathway that involves a redox mechanism. These findings reinforce the idea of targeting peripheral GABA receptors for pain relief. PMID:26239659

  2. Coupling ion-exchangers with inexpensive activated carbon fiber electrodes to enhance the performance of capacitive deionization cells for domestic wastewater desalination.

    Liang, Peng; Yuan, Lulu; Yang, Xufei; Zhou, Shaoji; Huang, Xia

    2013-05-01

    A capacitive deionization (CDI) cell was built with electrodes made of an inexpensive commercial activated carbon fiber (ACF), and then modified by incorporating ion-exchangers into the cell compartment. Three modified CDI designs were tested: MCDI - a CDI with electrodes covered by ion-exchange membranes (IEMs) of the same polarity, FCDI - a CDI with electrodes covered by ion-exchange felts (IEFs), and R-MCDI - an MCDI with cell chamber packed with ion-exchange resin (IER) granules. The cell was operated in the batch reactor mode with an initial salt concentration of 1000 mg/L NaCl, a typical level of domestic wastewater. The desalination tests involved investigations of two consecutive operation stages of CDIs: electrical adsorption (at an applied voltage of 1.2 V) and desorption [including short circuit (SC) desorption and discharge (DC) desorption]. The R-MCDI showed the highest electric adsorption as measured in the present study by desalination rate [670 ± 20 mg/(L h)] and salt removal efficiency (90 ± 1%) at 60 min, followed by the MCDI [440 ± 15 mg/(L h) and 60 ± 2%, respectively]. The superior desalination performance of the R-MCDI over other designs was also affirmed by its highest charge efficiency (110 ± 7%) and fastest desorption rates at both the SC [1960 ± 15 mg/(L·h)] and DC [3000 ± 20 mg/(L·h)] modes. The desalination rate and salt removal efficiency of the R-MCDI increased from ∼270 mg/(L h) and 83% to ∼650 mg/(L h) and 98% respectively when the applied voltage increased from 0.6 V to 1.4 V, while decreased slightly when lowering the salt water flow rate that fed into the cell. The packing of IER granules in the R-MCDI provided additional surface area for ions transfer; meanwhile, according to the results of electrochemical impedance spectroscopy (EIS) analysis, it substantially lower down the R-MCDI's ohmic resistance, resulting in improved desalination performance. PMID:23497976

  3. Molecular Interactions between Tarantula Toxins and Low-Voltage-Activated Calcium Channels.

    Salari, Autoosa; Vega, Benjamin S; Milescu, Lorin S; Milescu, Mirela

    2016-01-01

    Few gating-modifier toxins have been reported to target low-voltage-activated (LVA) calcium channels, and the structural basis of toxin sensitivity remains incompletely understood. Studies of voltage-gated potassium (Kv) channels have identified the S3b-S4 "paddle motif," which moves at the protein-lipid interface to drive channel opening, as the target for these amphipathic neurotoxins. Voltage-gated calcium (Cav) channels contain four homologous voltage sensor domains, suggesting multiple toxin binding sites. We show here that the S3-S4 segments within Cav3.1 can be transplanted into Kv2.1 to examine their individual contributions to voltage sensing and pharmacology. With these results, we now have a more complete picture of the conserved nature of the paddle motif in all three major voltage-gated ion channel types (Kv, Nav, and Cav). When screened with tarantula toxins, the four paddle sequences display distinct toxin binding properties, demonstrating that gating-modifier toxins can bind to Cav channels in a domain specific fashion. Domain III was the most commonly and strongly targeted, and mutagenesis revealed an acidic residue that is important for toxin binding. We also measured the lipid partitioning strength of all toxins tested and observed a positive correlation with their inhibition of Cav3.1, suggesting a key role for membrane partitioning. PMID:27045173

  4. On the Response of Interleaved Transformer Windings to Surge Voltages

    Pedersen, A.

    1963-01-01

    The high series capacitance theory for the response of interleaved transformer windings to surge voltages is criticized from the point of view that an increased series capacitance as a result of interleaving is incompatible with the concept of a pure capacitive initial voltage distribution. A new...

  5. Regulation of KV channel voltage-dependent activation by transmembrane β subunits

    Xiaohui eSun

    2012-04-01

    Full Text Available Voltage-activated K+ (KV channels are important for shaping action potentials and maintaining resting membrane potential in excitable cells. KV channels contain a central pore-gate domain (PGD surrounded by four voltage-sensing domains (VSD. The VSDs will change conformation in response to alterations of the membrane potential thereby inducing the opening of the PGD. Many KV channels are heteromeric protein complexes containing auxiliary β subunits. These β subunits modulate channel expression and activity to increase functional diversity and render tissue specific phenotypes. This review focuses on the KV β subunits that contain transmembrane (TM segments including the KCNE family and the β subunits of large conductance, Ca2+- and voltage-activated K+ (BK channels. These TM β subunits affect the voltage-dependent activation of KV α subunits. Experimental and computational studies have described the structural location of these β subunits in the channel complexes and the biophysical effects on VSD activation, PGD opening and VSD-PGD coupling. These results reveal some common characteristics and mechanistic insights into KV channel modulation by TM β subunits.

  6. Programmable electronic synthesized capacitance

    Kleinberg, Leonard L. (Inventor)

    1987-01-01

    A predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.

  7. Combined Digital Electronic Current and Voltage Transducer

    段雄英; 邹积岩; 等

    2002-01-01

    A high-performance current and voltage measurement system has been developed in power system.The system is composed of two parts:one current measurement element and one voltage measurement element.A Rogowski coil and a capacitive voltage divider are used respectively for the line current and voltage measurements.Active electronic components are used to modulate signal,and power supply for these components is drawn from power line via an auxiliary current transformer,Measurement signal is transmitted y optical fibers,which is resistant to electromagnetic induction and noise,With careful design and the use of digital signal processing technology,the whole system can meet 0.5% accuracy for metering and provides large dynamic range coupled with good accuracy for protective relaying use.

  8. Rapid and precise measurement of flatband voltage

    Li, S. P.; Ryan, M.; Bates, E. T.

    1976-01-01

    The paper outlines the design, principles of operation, and calibration of a five-IC network intended to give a rapid, precise, and automatic determination of the flatband voltage of MOS capacitors. The basic principle of measurement is to compare the analog output voltage of a capacitance meter - which is directly proportional to the capacitance being measured - with a preset or dialed-in voltage proportional to the calculated flatband capacitance by means of a comparator circuit. The bias to the MOS capacitor supplied through the capacitance meter is provided by a ramp voltage going from a negative toward a positive voltage level and vice versa. The network employs two monostable multivibrators for reading and recording the flatband voltage and for resetting the initial conditions and restarting the ramp. The flatband voltage can be held and read on a digital voltmeter.

  9. Grid-Voltage-Feedforward Active Damping for Grid-Connected Inverter with LCL Filter

    Lu, Minghui; Wang, Xiongfei; Blaabjerg, Frede; Muyeen, S.M.; Al-Durra, Ahmed; Leng, Siyu

    2016-01-01

    damping resistor and a reactance paralleled with filter capacitor. The damping performance in different frequency regions are discussed through Bode diagrams. Compared to other widely used active damping strategies, no extra sensor is needed because the Point of Common Coupling (PCC) voltage is sampled...

  10. Optimum PI Controllers of Active Power Filters for Harmonic Voltage Mitigation in Multibus Industrial Power Systems

    Tlustý, J.; Valouch, Viktor

    Palma de Mallorca: EA4EPQ, 2006, s. 1-5. ISBN 84-609-6604-6. [nternational Conference on Renewable Energies and Power Quality (ICREPQ'06). Palma de Mallorca (ES), 05.04.2006-07.04.2006] Institutional research plan: CEZ:AV0Z20570509 Keywords : active power filter * industrial power system * harmonic voltage mitigation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  11. Electrode Polarization in Glassy Electrolytes: Large Interfacial Capacitance Values and Indication for Pseudocapacitive Charge Storage

    Mariappan, C. R.; Heins, T. P.; Roling, B.

    2009-01-01

    We study the electrode polarization behaviour of different Na-Ca-phosphosilicate glasses by measuring the differential capacitance between blocking Pt electrodes. At low applied dc bias voltages, we detect a linear capacitance regime with interfacial capacitance values considerably larger than expected from double layer theories and also considerably larger than found for ionic liquids with similar ion concentrations. With increasing bias voltages, the differential capacitance of interfacial ...

  12. Extraordinary surface voltage effect in the invisibility cloak with an active device inside

    Zhang, Baile; Wu, Bae-Ian; Kong, Jin Au

    2007-01-01

    The electromagnetic field solution for a spherical invisibility cloak with an active device inside is established. It is found that extraordinary electric and magnetic surface voltages are induced at the inner boundary of a spherical cloak, which prevent electromagnetic waves from going out. The phase and handness information of polarized waves obliquely incident on such special boundaries is kept in the reflected waves. The values of the surface voltages due to an electric dipole with an arbitrary position inside the concealed region are found to be equal to the auxiliary scalar potentials, which consequently gain physical counterparts in this special case.

  13. Effect of ultrasonic treatment of activated carbon on capacitive and pseudocapacitive energy storage in electrochemical supercapacitors

    B.Ya. Venhryn; I.I. Grygorchak; Z.A. Stotsko; B.P. Bakhmatyuk; S.I. Mudry; Yu.O. Kulyk

    2013-01-01

    Purpose: Use of ultrasonic radiation for improving the properties of activated carbon was the aim of this paper. Increase of density of states at Fermi level was the main factor, responsible for working characteristics of electrochemical supercapacitors. Design/methodology/approach: Working parameters of supercapacitors on the base of activated carbon have been studied by means of precisional porometry, small angle X-ray scattering, cyclic voltamerometry, electrochemical im...

  14. Photocontrol of Voltage-Gated Ion Channel Activity by Azobenzene Trimethylammonium Bromide in Neonatal Rat Cardiomyocytes.

    Sheyda R Frolova

    Full Text Available The ability of azobenzene trimethylammonium bromide (azoTAB to sensitize cardiac tissue excitability to light was recently reported. The dark, thermally relaxed trans- isomer of azoTAB suppressed spontaneous activity and excitation propagation speed, whereas the cis- isomer had no detectable effect on the electrical properties of cardiomyocyte monolayers. As the membrane potential of cardiac cells is mainly controlled by activity of voltage-gated ion channels, this study examined whether the sensitization effect of azoTAB was exerted primarily via the modulation of voltage-gated ion channel activity. The effects of trans- and cis- isomers of azoTAB on voltage-dependent sodium (INav, calcium (ICav, and potassium (IKv currents in isolated neonatal rat cardiomyocytes were investigated using the whole-cell patch-clamp technique. The experiments showed that azoTAB modulated ion currents, causing suppression of sodium (Na+ and calcium (Ca2+ currents and potentiation of net potassium (K+ currents. This finding confirms that azoTAB-effect on cardiac tissue excitability do indeed result from modulation of voltage-gated ion channels responsible for action potential.

  15. Enhanced desalination performance of membrane capacitive deionization cells by packing the flow chamber with granular activated carbon.

    Bian, Yanhong; Yang, Xufei; Liang, Peng; Jiang, Yong; Zhang, Changyong; Huang, Xia

    2015-11-15

    A new design of membrane capacitive deionization (MCDI) cell was constructed by packing the cell's flow chamber with granular activated carbon (GAC). The GAC packed-MCDI (GAC-MCDI) delivered higher (1.2-2.5 times) desalination rates than the regular MCDI at all test NaCl concentrations (∼ 100-1000 mg/L). The greatest performance enhancement by packed GAC was observed when treating saline water with an initial NaCl concentration of 100 mg/L. Several different GAC materials were tested and they all exhibited similar enhancement effects. Comparatively, packing the MCDI's flow chamber with glass beads (GB; non-conductive) and graphite granules (GG; conductive but with lower specific surface area than GAC) resulted in inferior desalination performance. Electrochemical impedance spectroscopy (EIS) analysis showed that the GAC-MCDI had considerably smaller internal resistance than the regular MCDI (∼ 19.2 ± 1.2 Ω versus ∼ 1222 ± 15 Ω at 100 mg/L NaCl). The packed GAC also decreased the ionic resistance across the flow chamber (∼ 1.49 ± 0.05 Ω versus ∼ 1130 ± 12 Ω at 100 mg/L NaCl). The electric double layer (EDL) formed on the GAC surface was considered to store salt ions during electrosorption, and facilitate the ion transport in the flow chamber because of the higher ion conductivity in the EDLs than in the bulk solution, thereby enhancing the MCDI's desalination rate. PMID:26360230

  16. Superior decoupled control of active and reactive power for three-phase voltage source converters

    RAHBARIMAGHAM, HESAM; AMIRI, ERFAN MAALI; VAHIDI, Behrooz; GHAREHPETIAN, GEVORG BABAMALEK; Abedi, Mehrdad

    2015-01-01

    This paper presents an active-reactive power control strategy for voltage source converters (VSCs) based on derivation of the direct and quadrature components of the VSC output current. The proposed method utilizes a multivariable proportional-integral controller and provides almost completely decoupled control capability of the active and reactive power with almost full disturbance rejection due to step changes in the power exchanged between the VSC and the grid. It also imposes fast transie...

  17. False capacitance of supercapacitors

    Ragoisha, G. A.; Aniskevich, Y. M.

    2016-01-01

    Capacitance measurements from cyclic voltammetry, galvanostatic chronopotentiometry and calculation of capacitance from imaginary part of impedance are widely used in investigations of supercapacitors. The methods assume the supercapacitor is a capacitor, while real objects correspond to different equivalent electric circuits and show various contributions of non-capacitive currents to the current which is used for calculation of capacitance. Specific capacitances which are presented in F g-1...

  18. Effect of ultrasonic treatment of activated carbon on capacitive and pseudocapacitive energy storage in electrochemical supercapacitors

    B.Ya. Venhryn

    2013-10-01

    Full Text Available Purpose: Use of ultrasonic radiation for improving the properties of activated carbon was the aim of this paper. Increase of density of states at Fermi level was the main factor, responsible for working characteristics of electrochemical supercapacitors. Design/methodology/approach: Working parameters of supercapacitors on the base of activated carbon have been studied by means of precisional porometry, small angle X-ray scattering, cyclic voltamerometry, electrochemical impedance spectroscopy and computer simulation methods. Findings: The possibility to effect the interface between activated carbon and electrolyte by means of ultrasonic treatment in cavitation and noncavitation regimes is proved. It is shown that ultrasonic treatment in noncavitation regimes causes the significant increase of density of states at Fermi level that results in better farad-volt dependences. Research limitations/implications: This research is a complete and accomplished work. Practical implications: Modification of electric double layer by meanans in ultrasonic treatment, proposed in this work, could be regarded as effective way to obtaine the advanced electrode materials in devices of energy generation and storage. Originality/value: This work is important for physics, material science and chemistry because it is related with new possibilities to change the mobility of charge carries in electric double layer by means of ultrasonic irradiation.

  19. Study of CMOS integrated signal processing circuit in capacitive sensors

    CAO Yi-jiang; YU Xiang; WANG Lei

    2007-01-01

    A CMOS integrated signal processing circuit based on capacitance resonance principle whose structure is simple in capacitive sensors is designed. The waveform of output voltage is improved by choosing bootstrap reference current mirror with initiate circuit, CMOS analogy switch and positive feedback of double-stage inverter in the circuit. Output voltage of this circuit is a symmetric square wave signal. The variation of sensitive capacitance, which is part of the capacitive sensors, can be denoted by the change of output voltage's frequency. The whole circuit is designed with 1.5 μm P-well CMOS process and simulated by PSpice software.Output frequency varies from 261.05 kHz to 47.93 kHz if capacitance varies in the range of 1PF~15PF. And the variation of frequency can be easily detected using counter or SCU.

  20. Accurate sizing of supercapacitors storage system considering its capacitance variation.

    Trieste, Sony; Bourguet, Salvy; Olivier, Jean-Christophe; Loron, Luc; Le Claire, Jean-Claude

    2011-01-01

    This paper highlights the energy errors made for the design of supercapacitors used as a main energy source. First of all, the paper presents the two definitions of capacitance of a capacitance-voltage dependent material. The number of supercapacitors is important for the application purchasing cost. That is why the paper introduces an analytical model and an electrical model along with an identification method for the capacitance variation. This variation is presented and compared to the man...

  1. Interfacial gating triad is crucial for electromechanical transduction in voltage-activated potassium channels

    Chowdhury, Sandipan; Haehnel, Benjamin M.

    2014-01-01

    Voltage-dependent potassium channels play a crucial role in electrical excitability and cellular signaling by regulating potassium ion flux across membranes. Movement of charged residues in the voltage-sensing domain leads to a series of conformational changes that culminate in channel opening in response to changes in membrane potential. However, the molecular machinery that relays these conformational changes from voltage sensor to the pore is not well understood. Here we use generalized interaction-energy analysis (GIA) to estimate the strength of site-specific interactions between amino acid residues putatively involved in the electromechanical coupling of the voltage sensor and pore in the outwardly rectifying KV channel. We identified candidate interactors at the interface between the S4–S5 linker and the pore domain using a structure-guided graph theoretical approach that revealed clusters of conserved and closely packed residues. One such cluster, located at the intracellular intersubunit interface, comprises three residues (arginine 394, glutamate 395, and tyrosine 485) that interact with each other. The calculated interaction energies were 3–5 kcal, which is especially notable given that the net free-energy change during activation of the Shaker KV channel is ∼14 kcal. We find that this triad is delicately maintained by balance of interactions that are responsible for structural integrity of the intersubunit interface while maintaining sufficient flexibility at a critical gating hinge for optimal transmission of force to the pore gate. PMID:25311635

  2. Chemoselective tarantula toxins report voltage activation of wild-type ion channels in live cells

    Tilleya, DC; Euma, KS; Fletcher-Taylor, S; Austina, DC; Dupré, C; Patrón, LA; Garcia, RL; Lam, K; Yarov-Yarovoy, V; Cohenc, BE; Sack, JT

    2014-01-01

    Electrically excitable cells, such as neurons, exhibit tremendous diversity in their firing patterns, a consequence of the complex collection of ion channels present in any specific cell. Although numerous methods are capable of measuring cellular electrical signals, understanding which types of ion channels give rise to these signals remains a significant challenge. Here, we describe exogenous probes which use a novel mechanism to report activity of voltage-gated channels. We have synthesize...

  3. Connection of Shunt Active Power Filters in Multibus Industrial Power Systems for Harmonic Voltage Mitigation

    Tlustý, J.; Valouch, Viktor

    Zaragoza: EA4EPQ, 2005, s. 1-5. ISBN 84-609-3234-6. [International Conference on Renewable Energies and Power Quality (ICREPQ 05). Zaragoza (ES), 16.03.2005-18.03.2005] R&D Projects: GA ČR(CZ) GA102/03/1551; GA AV ČR(CZ) IAA2057301 Institutional research plan: CEZ:AV0Z20570509 Keywords : active power filter * industrial power system * harmonic voltage mitigation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  4. DOPAMINE RECEPTOR ACTIVATION CAN REDUCE VOLTAGE-GATED Na+ CURRENT BY MODULATING BOTH ENTRY INTO AND RECOVERY FROM INACTIVATION

    Hayashida, Yuki; Ishida, Andrew T.

    2004-01-01

    We tested whether dopamine receptor activation modulates the voltage-gated Na+ current of goldfish retinal ganglion cells, using a fast voltage-clamp amplifier, perforated-patch whole-cell mode, and a physiological extracellular Na+ concentration. As found in other cells, activators of D1-type dopamine receptors and of protein kinase A reduced the amplitude of current activated by depolarizations from resting potential, without altering the current kinetics or activation range. However, D1-ty...

  5. Performance analysis of active damped small DC-link capacitor based drive for unbalanced input voltage supply

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig

    A small DC-link capacitor based drive is presented in this paper. The drive shows negative impedance instability at operating points with high power load. A phase portrait is presented for input filter states which exhibit a limit cycle. When the drive is operated with unbalanced input supply...... voltages, the rectified voltage contains all even harmonics frequencies. However, it is shown that the dominant harmonic component of the DC-link voltage is decided by the limit cycle instead of the input filter resonance frequency. An active damping technique is used to stabilize the operating point. The...... responses of the DC-link voltage with and without active damping are presented. The low order harmonics components are reduced with the increase in the gain of the active damping term. The experimental results for the DC-link voltage, input phase currents, and machine phase current are presented....

  6. Real time control of an active power filter under distorted voltage condition

    Ahmed Safa

    2012-10-01

    Full Text Available

    This paper, presents three phase shunt active filter under distorted voltage condition, the active power filter control is based on the use of self-tuning filter (STF for reference current generation and on space vector PWM for generation of pulses. The dc capacitor voltage is controlled by a classical PI controller.  The diode rectifier feed RL load is taken as a nonlinear load. The self-tuning filter allows extracting directly the voltage and current fundamental components in the axis without phase locked loop (PLL under distorted voltage condition. The experiment analysis is made based on working under distorted voltage condition, and the total harmonic distortion of source current after compensation .Self tuning filter based extraction technique is good under distorted voltage conditions. The total harmonic distortion (THD of source current is fully reduced. The effectiveness of the method is theoretically studied and verified by experimentation.

  7. Comprehensive characterization of interface and oxide states in metal/oxide/semiconductor capacitors by pulsed mode capacitance and differential isothermal capacitance spectroscopy

    Muret, Pierre

    2014-01-01

    In metal/insulator/semi-conductor structures, capacitance-voltage characteristics and capacitance or voltage transients can be measured in different conditions, which are described and implemented. Each method contains information about charges which are accommodated, captured or emitted by energy levels or bands at interface and inside the oxide. Pulsed capacitance measurements and differential isothermal procedures are analysed and performed. Calibration of the energy scale from the interfa...

  8. Activity of Palythoa caribaeorum Venom on Voltage-Gated Ion Channels in Mammalian Superior Cervical Ganglion Neurons

    Lazcano-Pérez, Fernando; Castro, Héctor; Arenas, Isabel; García, David E.; González-Muñoz, Ricardo; Arreguín-Espinosa, Roberto

    2016-01-01

    The Zoanthids are an order of cnidarians whose venoms and toxins have been poorly studied. Palythoa caribaeorum is a zoanthid commonly found around the Mexican coastline. In this study, we tested the activity of P. caribaeorum venom on voltage-gated sodium channel (NaV1.7), voltage-gated calcium channel (CaV2.2), the A-type transient outward (IA) and delayed rectifier (IDR) currents of KV channels of the superior cervical ganglion (SCG) neurons of the rat. These results showed that the venom reversibly delays the inactivation process of voltage-gated sodium channels and inhibits voltage-gated calcium and potassium channels in this mammalian model. The compounds responsible for these effects seem to be low molecular weight peptides. Together, these results provide evidence for the potential use of zoanthids as a novel source of cnidarian toxins active on voltage-gated ion channels. PMID:27164140

  9. Activity of Palythoa caribaeorum Venom on Voltage-Gated Ion Channels in Mammalian Superior Cervical Ganglion Neurons.

    Lazcano-Pérez, Fernando; Castro, Héctor; Arenas, Isabel; García, David E; González-Muñoz, Ricardo; Arreguín-Espinosa, Roberto

    2016-01-01

    The Zoanthids are an order of cnidarians whose venoms and toxins have been poorly studied. Palythoa caribaeorum is a zoanthid commonly found around the Mexican coastline. In this study, we tested the activity of P. caribaeorum venom on voltage-gated sodium channel (NaV1.7), voltage-gated calcium channel (CaV2.2), the A-type transient outward (IA) and delayed rectifier (IDR) currents of KV channels of the superior cervical ganglion (SCG) neurons of the rat. These results showed that the venom reversibly delays the inactivation process of voltage-gated sodium channels and inhibits voltage-gated calcium and potassium channels in this mammalian model. The compounds responsible for these effects seem to be low molecular weight peptides. Together, these results provide evidence for the potential use of zoanthids as a novel source of cnidarian toxins active on voltage-gated ion channels. PMID:27164140

  10. Unfolding of a Temperature-Sensitive Domain Controls Voltage-Gated Channel Activation.

    Arrigoni, Cristina; Rohaim, Ahmed; Shaya, David; Findeisen, Felix; Stein, Richard A; Nurva, Shailika Reddy; Mishra, Smriti; Mchaourab, Hassane S; Minor, Daniel L

    2016-02-25

    Voltage-gated ion channels (VGICs) are outfitted with diverse cytoplasmic domains that impact function. To examine how such elements may affect VGIC behavior, we addressed how the bacterial voltage-gated sodium channel (BacNa(V)) C-terminal cytoplasmic domain (CTD) affects function. Our studies show that the BacNa(V) CTD exerts a profound influence on gating through a temperature-dependent unfolding transition in a discrete cytoplasmic domain, the neck domain, proximal to the pore. Structural and functional studies establish that the BacNa(V) CTD comprises a bi-partite four-helix bundle that bears an unusual hydrophilic core whose integrity is central to the unfolding mechanism and that couples directly to the channel activation gate. Together, our findings define a general principle for how the widespread four-helix bundle cytoplasmic domain architecture can control VGIC responses, uncover a mechanism underlying the diverse BacNa(V) voltage dependencies, and demonstrate that a discrete domain can encode the temperature-dependent response of a channel. PMID:26919429

  11. A high frequency active voltage doubler in standard CMOS using offset-controlled comparators for inductive power transmission.

    Lee, Hyung-Min; Ghovanloo, Maysam

    2013-06-01

    In this paper, we present a fully integrated active voltage doubler in CMOS technology using offset-controlled high speed comparators for extending the range of inductive power transmission to implantable microelectronic devices (IMD) and radio-frequency identification (RFID) tags. This active voltage doubler provides considerably higher power conversion efficiency (PCE) and lower dropout voltage compared to its passive counterpart and requires lower input voltage than active rectifiers, leading to reliable and efficient operation with weakly coupled inductive links. The offset-controlled functions in the comparators compensate for turn-on and turn-off delays to not only maximize the forward charging current to the load but also minimize the back current, optimizing PCE in the high frequency (HF) band. We fabricated the active voltage doubler in a 0.5-μm 3M2P std . CMOS process, occupying 0.144 mm(2) of chip area. With 1.46 V peak AC input at 13.56 MHz, the active voltage doubler provides 2.4 V DC output across a 1 kΩ load, achieving the highest PCE = 79% ever reported at this frequency. In addition, the built-in start-up circuit ensures a reliable operation at lower voltages. PMID:23853321

  12. Correcting For Capacitance In Tests Of Solar Cells

    Mueller, Robert L.

    1995-01-01

    Modified procedure for testing solar photovoltaic cells and modified software for processing test data provide corrections for effects of cell capacitance. Procedure and software needed because (a) some photovoltaic devices (for example, silicon solar cells with back-surface field region) store minority charge carriers in cell junction and thus exhibit significant capacitance, (b) capacitance affects current-vs.-voltage (I-V) measurements made when transient load connected to cell, and (c) transient load used in unmodified version of test procedure. Corrected I-V curve obtained in test of solar cell according to modified procedure approximates true cell voltage vs. cell current more closely.

  13. Design and Development of Autonomous High Voltage Driving System for DEAP Actuator in Radiator Thermostat

    Huang, Lina; Zhang, Zhe; Andersen, Michael A. E.

    2014-01-01

    make a high voltage capacitive load driving system to be necessary. The only energy source battery determines it needs to be an autonomous system. The detailed system specifications have been introduced and the corresponding system level design has been proposed. In addition, the detailed design......In radiator thermostat applications, DEAP (Dielectric Electro Active Polymer) actuator tends to be a good candidate to replace the conventional self-actuating or step motor based actuator due to its intrinsic advantages. The capacitive property and high voltage (HV) driving demand of DEAP actuator...... and implementation information has been provided as well, including the power and control stage inside the high voltage converter, the output voltage measurement circuit, the feedback control, etc. Finally, the experimental results have been provided to validate the capability and performance of the driving system....

  14. Design and Development of Autonomous High Voltage Driving System for DEAP Actuator in Radiator Thermostat

    Huang, Lina; Zhang, Zhe; Andersen, Michael A. E.

    In radiator thermostat applications, DEAP (Dielectric Electro Active Polymer) actuator tends to be a good candidate to replace the conventional self-actuating or step motor based actuator due to its intrinsic advantages. The capacitive property and high voltage (HV) driving demand of DEAP actuator...... make a high voltage capacitive load driving system to be necessary. The only energy source battery determines it needs to be an autonomous system. The detailed system specifications have been introduced and the corresponding system level design has been proposed. In addition, the detailed design and...... implementation information has been provided as well, including the power and control stage inside the high voltage converter, the output voltage measurement circuit, the feedback control, etc. Finally, the experimental results have been provided to validate the capability and performance of the driving system....

  15. Cell swelling activates ATP-dependent voltage-gated chloride channels in M-1 mouse cortical collecting duct cells

    1996-01-01

    In the present study we used whole-cell patch clamp recordings to investigate swelling-activated Cl-currents (ICl-swell) in M-1 mouse cortical collecting duct (CCD) cells. Hypotonic cell swelling reversibly increased the whole-cell Cl- conductance by about 30-fold. The I-V relationship was outwardly-rectifying and ICl-swell displayed a characteristic voltage-dependence with relatively fast inactivation upon large depolarizing and slow activation upon hyperpolarizing voltage steps. Reversal po...

  16. Minimization of the transformer inter-winding parasitic capacitance for modular stacking power supply applications

    Nguyen-Duy, Khiem; Ouyang, Ziwei; Knott, Arnold;

    2014-01-01

    In an isolated power supply, the inter-winding parasitic capacitance plays a vital role in the mitigation of common mode noise currents created by fast voltage transient responses. The lower the transformer inter-winding capacitance, the more immune the power supply is to fast voltage transient...

  17. Corrections to the Capacitance between Two Electrodes Due to the Presence of Quantum Confined System

    Macucci, M.; K. Hess

    1998-01-01

    We have studied the capacitance between two parallel plates enclosing a quantum confined system and its dependence on the applied voltage. The concepts of capacitance and differential capacitance are discussed together with their applicability to systems characterized by single.electron tunneling. We determine the tunneling thresholds by means of a formalism based on the minimization of the system free energy and we retrieve, as a special case, Luryi's quantum capacitance formula. We apply ou...

  18. Mesoscopic Capacitance Oscillations

    Buttiker, Markus; Nigg, Simon

    2006-01-01

    We examine oscillations as a function of Fermi energy in the capacitance of a mesoscopic cavity connected via a single quantum channel to a metallic contact and capacitively coupled to a back gate. The oscillations depend on the distribution of single levels in the cavity, the interaction strength and the transmission probability through the quantum channel. We use a Hartree-Fock approach to exclude self-interaction. The sample specific capacitance oscillations are in marked contrast to the c...

  19. Phosphorus/sulfur Co-doped porous carbon with enhanced specific capacitance for supercapacitor and improved catalytic activity for oxygen reduction reaction

    Zhou, Yao; Ma, Ruguang; Candelaria, Stephanie L.; Wang, Jiacheng; Liu, Qian; Uchaker, Evan; Li, Pengxi; Chen, Yongfang; Cao, Guozhong

    2016-05-01

    Phosphorus (P)/sulfur (S) co-doped porous carbon derived from resorcinol and furaldehyde are synthesized through one-step sol-gel processing with the addition of phosphorus pentasulfide as P and S source followed with freeze-drying and pyrolysis in nitrogen. The P/S co-doping strategy facilitates the pore size widening both in micropore and mesopore regions, together with the positive effect on the degree of graphitization of porous carbon through elimination of amorphous carbon through the formation and evaporation of carbon disulfide. As an electrode for supercapacitor application, P/S co-doped porous carbon demonstrates 43.5% improvement on specific capacitance of the single electrode compared to pristine porous carbon in organic electrolyte at a current of 0.5 mA due to the P-induced pseudocapacitive reactions. As for electrocatalytic use, promoted electrocatalytic activity and high resistance to crossover effects of oxygen reduction reaction (ORR) in alkaline media are observed after the introduction of P and S into porous carbon. After air activation, the specific capacitance of the single electrode of sample PS-pC reaches up to 103.5 F g-1 and an improved oxygen reduction current density.

  1. The effect of ultrasonic and HNO3 treatment of activated carbon from fruit stones on capacitive and pseudocapacitive energy storage in electrochemical supercapacitors.

    Venhryn, B Ya; Stotsko, Z A; Grygorchak, I I; Bakhmatyuk, B P; Mudry, S I

    2013-09-01

    The effect of ultrasonic treatment and modification with nitric acid of activated carbon obtained from fruit stones, on the parameters of electric double-layer (EDL) as well as on farad-volt characteristics of its boundary with electrolyte 7.6 m KОН, 4 m KI and 2 m ZnI2 aqueous solutions has been studied by means of precision porometry, cyclic voltamperometry, electrochemical impedance spectroscopy and computer simulation methods. It is shown that HNO3 treatment results in an increase of the electrostatic capacitance up to 202 F/g in 7.6 m KОН-solution as well as pseudocapacitance up to 1250 F/g in 4 m KI. This increase is supposed to be related both with hydrophilicity and with an increase of the density of states on Fermi level. The ultrasonic treatment enables one to significantly increase (more than 200 times) the density of states on Fermi level which in turn causes both quantitative and qualitative changes in farad-volt dependences. A hybrid supercapacitor with specific capacitance of 1100 F/g and specific energy of 49 Wh/kg per active mass of two electrodes was developed. PMID:23541908

  2. High voltage pulse conditioning

    Springfield, Ray M.; Wheat, Jr., Robert M.

    1990-01-01

    Apparatus for conditioning high voltage pulses from particle accelerators in order to shorten the rise times of the pulses. Flashover switches in the cathode stalk of the transmission line hold off conduction for a determinable period of time, reflecting the early portion of the pulses. Diodes upstream of the switches divert energy into the magnetic and electrostatic storage of the capacitance and inductance inherent to the transmission line until the switches close.

  3. VOLTAGE REGULATORS ASYNCHRONOUS GENERATORS

    Grigorash O. V.; Bogatyrev N. I.; Hitskova A. O.

    2015-01-01

    A promising is currently the use of asynchronous generators with capacitive excitation as a source of electricity in stand-alone power systems. Drive asynchronous generators may exercise as a thermal engine and wind wheel wind power plant or turbines of small hydropower plants. The article discusses the structural and schematics of voltage stabilizers and frequency of asynchronous generators with improved operational and technical specifications. Technical novelty of design solutions of the m...

  4. Voltage-gated Na+ Channel Activity Increases Colon Cancer Transcriptional Activity and Invasion Via Persistent MAPK Signaling

    House, Carrie D.; Wang, Bi-Dar; Ceniccola, Kristin; Williams, Russell; Simaan, May; Olender, Jacqueline; Patel, Vyomesh; Baptista-Hon, Daniel T.; Annunziata, Christina M.; Silvio Gutkind, J.; Hales, Tim G.; Lee, Norman H.

    2015-06-01

    Functional expression of voltage-gated Na+ channels (VGSCs) has been demonstrated in multiple cancer cell types where channel activity induces invasive activity. The signaling mechanisms by which VGSCs promote oncogenesis remain poorly understood. We explored the signal transduction process critical to VGSC-mediated invasion on the basis of reports linking channel activity to gene expression changes in excitable cells. Coincidentally, many genes transcriptionally regulated by the SCN5A isoform in colon cancer have an over-representation of cis-acting sites for transcription factors phosphorylated by ERK1/2 MAPK. We hypothesized that VGSC activity promotes MAPK activation to induce transcriptional changes in invasion-related genes. Using pharmacological inhibitors/activators and siRNA-mediated gene knockdowns, we correlated channel activity with Rap1-dependent persistent MAPK activation in the SW620 human colon cancer cell line. We further demonstrated that VGSC activity induces downstream changes in invasion-related gene expression via a PKA/ERK/c-JUN/ELK-1/ETS-1 transcriptional pathway. This is the first study illustrating a molecular mechanism linking functional activity of VGSCs to transcriptional activation of invasion-related genes.

  5. N-cadherin modulates voltage activated calcium influx via RhoA, p120-catenin, and myosinactin interaction

    Marrs, Glen S.; Theisen, Christopher S.; Brusés, Juan L.

    2008-01-01

    N-cadherin is a transmembrane adhesion receptor that contributes to neuronal development and synapse formation through homophilic interactions that provide structural-adhesive support to contacts between cell membranes. In addition, N-cadherin homotypic binding may initiate cell signaling that regulates neuronal physiology. In this study, we investigated signaling capabilities of N-cadherin that control voltage activated calcium influx. Using whole-cell voltage clamp recording of isolated inw...

  6. Complementary surface charge for enhanced capacitive deionization

    Gao, X.; Porada, S.; Omosebi, A.; Liu, K.L.; Biesheuvel, P.M.; Landon, J.

    2016-01-01

    Commercially available activated carbon cloth electrodes are treated using nitric acid and ethylenediamine solutions, resulting in chemical surface charge enhanced carbon electrodes for capacitive deionization (CDI) applications. Surface charge enhanced electrodes are then configured in a CDI cel

  7. Effect of New O-Superfamily Conotoxin on Voltage-Activated Currents of Hippocampal Neurons

    李湛; 何湘平; 戴秋云; 黄培堂; 谢佐平

    2004-01-01

    The effects of a new O-superfamily conotoxin, SO3, on sodium current (/Na), transient A-type potassium currents (/A), and delayed rectified potassium currents (/K), were examined in cultured rat hippocampal neurons using the whole-cell patch clamp technique. Addition of SO3 caused a concentration-dependent,rapidly developing, and reversible inhibition of voltage-activated currents. The IC50 values for the blockage of /Na, /A, and /K were calculated as 0.49, 33.9, and 7.6 μmol/L, respectively. The determined Hill coefficients were 1.7, 0.6, and 1.2, respectively. These results indicate that SO3 can selectively inhibit neuronal sodium and potassium currents.

  8. Variable Synthetic Capacitance

    Kleinberg, L. L.

    1986-01-01

    Feedback amplifier circuit synthesizes electronically variable capacitance. Variable Synthetic Capacitor is amplifier circuit with follower/feedback configuration. Effective input capacitance depends on input set current. If synthetic capacitor is connected across resonant element of oscillator, oscillator frequency controlled via input set current. Circuit especially suitable for fine frequency adjustments of piezoelectric-crystal or inductor/capacitor resonant oscillators.

  9. 高速铁路全电缆电力贯通线的电容电流及其容性无功补偿分析%Analysis of Capacitive Current and Capacitive Reactive Compensation in the Medium-voltage of All-cable Through Line on High-speed Railway

    张凉永

    2015-01-01

    Though the reliability of power supply system with all-cable through line is improved greatly, a series of prob-lems occur, such as terminal overvoltage, increasing of capacitive reactive power, lower system efficiency, switching ov-ervoltage and arc overvoltage under single-phase grounding fault due to excessive capacitive current in the power supply system of high-speed railway. According to common configuration of power through line on high-speed railway, an analy-sis is made on distribution and parameter level of capacitive current of cable line under normal working conditions and single-phase grounding fault. The theoretical analysis and comparison are made on horizontal difference of capacitive cur-rent between single-core cable and three-core cable, through analysis and comparison, it is concluded that single-core cable is more reliable than three-core cable. Suggestions are given for calculation of reactor compensating capacity, veri-fication of compensated capacitive current and selection of neutral point grounding mode in the engineering design.%在高速铁路电力供配电系统中,采用全电缆贯通线方案供电系统可靠性得以大幅提高的同时,电容电流过大会带来末端电压超标、容性无功增加、系统效率降低、操作过电压、单相接地故障下的电弧过电压等一系列问题。文章针对高速铁路电力贯通线的常见配置,在正常运行和单项接地故障情况下,对电缆线路电容电流分布及其参数水平予以分析。并通过对单芯电缆和三芯电缆方案的电容电流水平差异进行理论分析和比较,得出全线路单芯电缆敷设方案在可靠性上具备明显优势的结论。并提出了在工程设计中的电抗器补偿容量计算、补偿后电容电流的校验以及供配电系统中性点接地方式选择的建议。

  10. Resonant-inductor-voltage feedback active damping based control for grid-connected inverters with LLCL-filters

    Huang, Min; Wang, Xiongfei; Loh, Poh Chiang;

    2014-01-01

    LLCL-filter is recently emerging into grid-connected inverters due to its high attenuation of high-frequency harmonics with a smaller size. Active damping methods have been proposed to reduce the resonance peak caused by the LLCL-filter to stabilize the whole system without extra losses. The active......-phase grid-connected voltage source inverter (VSI). The design method is described through the analysis in the s-domain and the z-domain. Then the robustness and harmonic rejection of the grid voltage with the active damping method is analyzed considering the processing delay. Finally, the performance of the...

  11. A Fast Series Active Filter using Sliding Mode Control to Correct and Regulate Unbalance Voltage in Three-Phase System

    Theerayuth Chatchanayuenyong

    2009-01-01

    Full Text Available Problem statement: A Sliding Mode Controller (SMC with fast reference voltage generation to correct and regulate unbalance voltage in three-phase system was proposed. Approach: The compensation algorithm was not based on three-symmetrical component decomposition so the controller can yield a fast response that was essential in such a critical real time control work. The reference voltages were fed to the SMC, which was a robust closed loop controller. Results: The proposed algorithm and control scheme of series active filter could correct and regulate unbalance voltage in three-phase system under arbitrary fault conditions of the utility supply. Conclusion: A design example and its simulation results proved the concept and validated the proposed algorithm.

  12. Capacitively coupled hybrid pixel assemblies for the CLIC vertex detector

    Alipour Tehrani, Niloufar; Benoit, Mathieu; Dannheim, Dominik; Dette, Karola; Hynds, Daniel; Kulis, Szymon; Peric, Ivan; Petric, Marko; Redford, Sophie; Sicking, Eva; Valerio, Pierpaolo

    2015-01-01

    The vertex detector at the proposed CLIC multi-TeV linear e+e- collider must have minimal material content and high spatial resolution, combined with accurate time-stamping to cope with the expected high rate of beam-induced backgrounds. One of the options being considered is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel ASICs. A prototype of such an assembly, using two custom designed chips (CCPDv3 as active sensor glued to a CLICpix readout chip), has been characterised both in the lab and in beam tests at the CERN SPS using 120 GeV/c positively charged hadrons. Results of these characterisation studies are presented both for single and dual amplification stages in the active sensor. Pixel cross-coupling results are also presented, showing the sensitivity to placement precision and planarity of the glue layer.

  13. 聚吡咯修饰活性炭电极的电容去离子应用研究%Application of polypyrrole modified activated carbon electrode to capacitive deionization

    徐克; 肖书彬; 阮国岭

    2012-01-01

    The polypyrrole/activated carbon(Ppy/AC) composite electrode has been fabricated by chemical oxidative polymerization. And the mass ratio of pyrrole(py) and AC has also been investigated to improve the capacitive deionization performance of composite electrodes. The experimental results show that Ppy could significantly improve the specific capacitance of composite electrodes. But the enlargement of active material loading would make the specific capacitance of composite electrodes decrease obviously, despite the increase of capacitance in this process. At the optimal mass ratio of pyrrole and AC (0.4: 1) ,the composite electrodes show relatively higher capacitance and specific capacitance, which could efficiently improve the capacitive deionization performance of composite electrodes.%采用化学氧化法制备了聚吡咯(PPy)/活性炭(AC)复合电极,并通过在制备过程中优化吡咯(py)与AC的质量比,提升复合电极的电容去离子性能.实验结果显示,PPy可有效提升复合电极的比电容,但在活性材料负载量增大时,电极充放电电容快速增大的同时,比电容明显下降;当m(py):m(AC)=0.4:1时,复合电极在高活性物质负载量下仍然显示出较高的充放电电容和比电容,有效提升了复合电极的电容去离子性能.

  14. The Activity of Ubiquitin Activating Enzyme UBA1 Is Required for Sperm Capacitation, Acrosornal Exocytosis, and Sperm-Egg Coat Penetration During Porcine Fertilization

    Yi, Y.N.; Zimmermann, S.W.; Manandhar, G.; Odhiambo, J.F.; Jonáková, Věra; Sutovsky, M.; Park, C.S.; Sutovsky, P.

    supplement, - (2010), s. 169-170. ISSN 0006-3363. [43rd Annual Meeting of the Society for the Study of Reproduction. 31.07.2010-03.08.2010, Milwaukee] Institutional research plan: CEZ:AV0Z50520701 Keywords : ubiquitin * capacitation * fertilization Subject RIV: CE - Biochemistry

  15. Capacitive Sensor With Driven Shields And Bridge Circuit

    Vranish, John M.

    1994-01-01

    Like other capaciflectors described in prior articles in NASA Tech Briefs, this one includes sensing electrode driven by alternating voltage, giving rise to electric field in vicinity of electrode; object entering electric field detected by its effect on capacitance between sensing electrode and electrical ground. Also includes shielding electrode (in this case, driven shield 1), excited via voltage follower at same voltage as that applied to sensing electrode to concentrate more of electric field outward from sensing electrode, increasing sensitivity and range of sensor. Because shielding electrode driven via voltage follower, it does not present significant electrical load to source of alternating voltage.

  16. The fringe capacitance formula of microstructures

    This paper presents a fringe capacitance formula of microstructures. The formula is derived by curve fitting on ANSYS simulation results. Compared with the ANSYS and experimental results, the deviation is within ±2%. The application to determine the pull-in voltage of an electrostatic micro-beam is demonstrated, which agrees very well with the experimental data. The formula presented is very accurate, yields explicit physical meanings and is applicable to common dimension ranges for MEMS devices. (paper)

  17. L-type voltage-operated calcium channels contribute to astrocyte activation In vitro.

    Cheli, Veronica T; Santiago González, Diara A; Smith, Jessica; Spreuer, Vilma; Murphy, Geoffrey G; Paez, Pablo M

    2016-08-01

    We have found a significant upregulation of L-type voltage-operated Ca(++) channels (VOCCs) in reactive astrocytes. To test if VOCCs are centrally involved in triggering astrocyte reactivity, we used in vitro models of astrocyte activation in combination with pharmacological inhibitors, siRNAs and the Cre/lox system to reduce the activity of L-type VOCCs in primary cortical astrocytes. The endotoxin lipopolysaccharide (LPS) as well as high extracellular K(+) , glutamate, and ATP promote astrogliosis in vitro. L-type VOCC inhibitors drastically reduce the number of reactive cells, astrocyte hypertrophy, and cell proliferation after these treatments. Astrocytes transfected with siRNAs for the Cav1.2 subunit that conducts L-type Ca(++) currents as well as Cav1.2 knockout astrocytes showed reduce Ca(++) influx by ∼80% after plasma membrane depolarization. Importantly, Cav1.2 knock-down/out prevents astrocyte activation and proliferation induced by LPS. Similar results were found using the scratch wound assay. After injuring the astrocyte monolayer, cells extend processes toward the cell-free scratch region and subsequently migrate and populate the scratch. We found a significant increase in the activity of L-type VOCCs in reactive astrocytes located in the growing line in comparison to quiescent astrocytes situated away from the scratch. Moreover, the migration of astrocytes from the scratching line as well as the number of proliferating astrocytes was reduced in Cav1.2 knock-down/out cultures. In summary, our results suggest that Cav1.2 L-type VOCCs play a fundamental role in the induction and/or proliferation of reactive astrocytes, and indicate that the inhibition of these Ca(++) channels may be an effective way to prevent astrocyte activation. GLIA 2016. GLIA 2016;64:1396-1415. PMID:27247164

  18. Direct measurement of specific membrane capacitance in neurons.

    Gentet, L.J.; Stuart, G J; Clements, J D

    2000-01-01

    The specific membrane capacitance (C(m)) of a neuron influences synaptic efficacy and determines the speed with which electrical signals propagate along dendrites and unmyelinated axons. The value of this important parameter remains controversial. In this study, C(m) was estimated for the somatic membrane of cortical pyramidal neurons, spinal cord neurons, and hippocampal neurons. A nucleated patch was pulled and a voltage-clamp step was applied. The exponential decay of the capacitative char...

  19. Capacitive Coupling in Double-Circuit Transmission Lines

    Zdenka Benesova

    2004-01-01

    Full Text Available The paper describes an algorithm for calculation of capacitances and charges on conductors in systems with earth wires and in double-circuit overhead lines with respect to phase arrangement. A balanced voltage system is considered. A suitable transposition of individual conductors enables to reduce the electric and magnetic fields in vicinity of overhead lines and to limit the inductive and capacitive linkage. The procedure is illustrated on examples the results of which lead to particular recommendations for designers.

  20. New zero voltage switching DC converter with flying capacitors

    Lin, Bor-Ren; Shiau, Tung-Yuan

    2016-04-01

    A new soft switching converter is presented for medium power applications. Two full-bridge converters are connected in series at high voltage side in order to limit the voltage stress of power switches at Vin/2. Therefore, power metal-oxide-semiconductor field-effect transistors (MOSFETs) with 600 V voltage rating can be adopted for 1200 V input voltage applications. In order to balance two input split capacitor voltages in every switching cycle, two flying capacitors are connected on the AC side of two full-bridge converters. Phase-shift pulse-width modulation (PS-PWM) is adopted to regulate the output voltage. Based on the resonant behaviour by the output capacitance of MOSFETs and the resonant inductance, active MOSFETs can be turned on under zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. Two full-bridge converters are used in the proposed circuit to share load current and reduce the current stress of passive and active components. The circuit analysis and design example of the prototype circuit are provided in detail and the performance of the proposed converter is verified by the experiments.

  1. Negative capacitance shunt damping system with optimized characteristics for use with piezoelectric transducers

    Pohl, Martin

    2014-03-01

    For ecologic sustainability and decreasing reserves of fossile energy sources, fuel efficiency is a major concern especially for passenger aircraft. Therefore, lightweight structures made from carbon fiber plastics offer great potential. But when used for panel-like structures, they have the disadvantage of lower damping and coincidence frequencies compared to conventional differential metal constructions. Both aspects lead to an increased vibration level and by this a higher noise radiation. Because of this, special noise and vibration treatment is needed to ensure passenger cabin comfort. Besides passive damping and active structural acoustic control (ASAC), piezoelectric shunt damping is investigated. Due to its broadband performance, the negative capacitance shunt can be used for multimode systems with varying eigenfrequencies. These shunts are usually built with operational amplifiers and passive components as resistors and capacitors. This setup is sufficient for laboratory tests at low excitation levels. In fact, it is not capable of accessing the full voltage amplitude of common piezoelectric transducers, because most operational amplifiers only deliver +/-15V maximum output voltage. Therefore an improved setup is presented in this paper, which addresses the specific voltage requirements of a common piezoelectric transducer to achieve best performance. It comprises a tailored power source and an appropriate concept for the negative capacitance shunt hardware. This new hardware only uses standard operational amplifiers together with a high voltage power amplifier to cover the whole operating range of a piezoelectric transducer. A demonstrator board is developed and experimentally investigated at a test structure. Finally, the results are compared to a conventional setup.

  2. System for Measuring Capacitance

    McNichol, Randal S. (Inventor)

    2001-01-01

    A system has been developed for detecting the level of a liquid in a tank wherein a capacitor positioned in the tank has spaced plates which are positioned such that the dielectric between the plates will be either air or the liquid, depending on the depth of the liquid in the tank. An oscillator supplies a sine wave current to the capacitor and a coaxial cable connects the capacitor to a measuring circuit outside the tank. If the cable is very long or the capacitance to be measured is low, the capacitance inherent in the coaxial cable will prevent an accurate reading. To avoid this problem, an inductor is connected across the cable to form with the capacitance of the cable a parallel resonant circuit. The impedance of the parallel resonant circuit is infinite, so that attenuation of the measurement signal by the stray cable capacitance is avoided.

  3. Capacitance pressure sensor

    Eaton, William P.; Staple, Bevan D.; Smith, James H.

    2000-01-01

    A microelectromechanical (MEM) capacitance pressure sensor integrated with electronic circuitry on a common substrate and a method for forming such a device are disclosed. The MEM capacitance pressure sensor includes a capacitance pressure sensor formed at least partially in a cavity etched below the surface of a silicon substrate and adjacent circuitry (CMOS, BiCMOS, or bipolar circuitry) formed on the substrate. By forming the capacitance pressure sensor in the cavity, the substrate can be planarized (e.g. by chemical-mechanical polishing) so that a standard set of integrated circuit processing steps can be used to form the electronic circuitry (e.g. using an aluminum or aluminum-alloy interconnect metallization).

  4. Capacitive chemical sensor

    Manginell, Ronald P; Moorman, Matthew W; Wheeler, David R

    2014-05-27

    A microfabricated capacitive chemical sensor can be used as an autonomous chemical sensor or as an analyte-sensitive chemical preconcentrator in a larger microanalytical system. The capacitive chemical sensor detects changes in sensing film dielectric properties, such as the dielectric constant, conductivity, or dimensionality. These changes result from the interaction of a target analyte with the sensing film. This capability provides a low-power, self-heating chemical sensor suitable for remote and unattended sensing applications. The capacitive chemical sensor also enables a smart, analyte-sensitive chemical preconcentrator. After sorption of the sample by the sensing film, the film can be rapidly heated to release the sample for further analysis. Therefore, the capacitive chemical sensor can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  5. ESTIMATION OF DECREASING LOSSES OF ACTIVE POWER IN TRANSFORMERS IN SETTING BATTERY OF LOW-VOLTAGE CAPACITORS

    V. N. Radkevich

    2014-01-01

    Full Text Available This paper describes an estimation method of decreasing losses of active power in power transformers with voltage 10(6/0,4 kV after installation of devices of reactive power compensation on output side depending on voltage level, connected to capacity devices, taking into account dielectric loss in capacitors. Analysis of functional dependences was carried out. Investigation of function with a help of derivations was carried out. Points of function extremum and also its intervals of rise and fall rates were founded. This paper describes graphic investigation of obtained functional dependence, which is introduced by quartic polynominal. It is established that decreasing of losses of active power depends on technical parameters and load factor of transformer, coefficient of loading power of electricity consumers, voltage value connected to capacitor unit.Using obtained functional dependences, calculations for the main size-types of power transformers with voltage 10(6/0,4 kV serie ТМГ 11 and ТМГ12 were done. It is established that depending on technical characteristics of certain transformer, coefficient of its loading and power, there is a definite value of deviation of real voltage value from working voltage of capacitor installation when it will be observed positive technical and economical effect from installed capacitor battery unit. For taken value of loading coefficient and transformer’s power the maximum decrease of losses of active power takes place under voltage directed to capacitor unit, which is lower then nominal value. For all taken size-types of power transformers the argument of investigating function for its maximal value is out of standard permissible of voltage deviations from nominal value.These functional dependents can be used for preliminary calculations, which are needed for making decision on compensation of reactive power in electric power supply systems of industrial objects. Their consideration allows more

  6. High Voltage Electrostatic Pendulum

    Baddi, Raju

    2012-01-01

    A pendulum powered by high voltage electricity is described. The pendulum consists of two conducting plates(thin foil) separated by copper rods and are insulated from each other. High voltage is applied to these plates through the connecting copper rods. Another stationary aluminum plate(thin foil) is placed in front of the pendulum such that it serves to attract the pendulum plates and makes electrical contact with them enabling charge transfer between the stationary plate and the pendulum plates. The pendulum is powered by the energy stored in the capacitance between the stationary aluminum plate and the pendulum plate. Attempt has been made to obtain the time period of oscillations as a function of applied voltage and other parameters. The derived formula for the time period has been verified experimentally. This apparatus can be used to demonstrate electrical phenomena in general and in particular electrical energy stored in conductors of small dimensions.

  7. Full-bridge capacitive extensometer

    Peters, Randall D.

    1993-08-01

    Capacitive transducers have proven to be very effective sensors of small displacements, because of inherent stability and noninvasive high resolution. The most versatile ones have been those of a differential type, in which two elements are altered in opposite directions in response to change of the system parameter being monitored. Oftentimes, this differential pair has been incorporated into a bridge circuit, which is a useful means for employing synchronous detection to improve signal to noise ratios. Unlike previous differential capacitive dilatometers which used only two active capacitors, the present sensor is a full-bridge type, which is well suited to measuring low-level thermal expansions. This analog sensor is capable of 0.1 μm resolution anywhere within a range of several centimeters, with a linearity of 0.1%. Its user friendly output can be put on a strip chart recorder or directed to a computer for sophisticated data analysis.

  8. Induced Charge Capacitive Deionization

    Rubin, S.; Suss, M. E.; Biesheuvel, P. M.; Bercovici, M.

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, ...

  9. Modeling and analysis of the membrane-behavior in capacitive micromachined ultrasonic transducer

    In this study, theoretical analysis and finite element analysis of the behavior of membrane (such as resonance frequency, membrane deflection, collapse deflection and collapse voltage) in the capacitive micromachined ultrasonic transducer (cMUT) were performed. The design parameter of the cMUT were estimated and are the dimension and thickness of membrane, thickness of sacrificed layer, thickness and size of electrode, size of active element and so on. The resonance frequency of the membrane increased as the thickness of the membrane increased but decreased as the diameter of the membrane increased. The deflection of the membrane increased as d-c bias voltage increased. The collapse voltage of the membrane was predicted.

  10. Modeling and analysis of the membrane-behavior in capacitive micromachined ultrasonic transducer

    In this study, theoretical analysis and finite element analysis of the behavior of membrane (such as resonance frequency, membrane deflection, collapse deflection and collapse voltage) in the capacitive micromachined ultrasonic transducer (cMUT) were performed. The design parameters of the cMUT were estimated and are the dimension and thickness of membrane, thickness of sacrificial layer, thickness and size of electrode, size of active element and so on. The resonance frequency of the membrane increased as the thickness of the membrane increased but decreased as the diameter of the membrane increased. The deflection of the membrane increased as d-c bias voltage increased. The collapse voltage of the membrane was predicted.

  11. The Activity of Ubiquitin Activating Enzyme UBA1 is Required for Sperm Capacitation, Acrosomal Exocytosis and Sperm-Egg Coat Penetration during Porcine Fertilization

    Yi, Y.-J.; Zimmerman, S.W.; Manandhar, G.; Odhiambo, J.F.; Jonáková, Věra; Sutovsky, M.; Park, C.-S.; Sutovsky, P.

    Milwaukee : Society for the Study of Reproduction, 2010. s. 125. ISSN 0006-3363. [43rd Annual Meeting of the Society for the Study of Reproduction / "The Intersection between Genetics, Genomics, and Reproductive Biology"/. 30.07.2010-03.08.2010, Milwaukee] Institutional research plan: CEZ:AV0Z50520701 Keywords : Ubiquitin * Acrosin-inhibitor * Spermadhesin * Sperm capacitation * Fertilization * Acrosomal exocytosis Subject RIV: CE - Biochemistry

  12. Integrated high voltage power supply utilizing burst mode control and its performance impact on dielectric electro active polymer actuators

    Andersen, Thomas; Rødgaard, Martin Schøler; Andersen, Michael A. E.; Thomsen, Ole Cornelius; Lorenzen, K. P.; Mangeot, C.; Steenstrup, A. R.

    Through resent years new high performing Dielectric Electro Active Polymers (DEAP) have emerged. To fully utilize the potential of DEAPs a driver with high voltage output is needed. In this paper a piezoelectric transformer based power supply for driving DEAP actuators is developed, utilizing a...

  13. Active damping of LLCL-filter resonance based on LC-trap voltage and capacitor current feedback

    Huang, Min; Wang, Xiongfei; Loh, Poh Chiang;

    2015-01-01

    paper, different feedback coefficients like the proportional, derivative, integral, high pass and low pass feedback coefficients of the filter capacitor current and the LC-trap circuit voltage are investigated for damping the filter resonance. Active damping methods are analyzed by using the concept of...

  14. Monitoring Integrated Activity of Individual Neurons Using FRET-Based Voltage-Sensitive Dyes.

    Briggman, Kevin L; Kristan, William B; González, Jesús E; Kleinfeld, David; Tsien, Roger Y

    2015-01-01

    Pairs of membrane-associated molecules exhibiting fluorescence resonance energy transfer (FRET) provide a sensitive technique to measure changes in a cell's membrane potential. One of the FRET pair binds to one surface of the membrane and the other is a mobile ion that dissolves in the lipid bilayer. The voltage-related signal can be measured as a change in the fluorescence of either the donor or acceptor molecules, but measuring their ratio provides the largest and most noise-free signal. This technology has been used in a variety of ways; three are documented in this chapter: (1) high throughput drug screening, (2) monitoring the activity of many neurons simultaneously during a behavior, and (3) finding synaptic targets of a stimulated neuron. In addition, we provide protocols for using the dyes on both cultured neurons and leech ganglia. We also give an updated description of the mathematical basis for measuring the coherence between electrical and optical signals. Future improvements of this technique include faster and more sensitive dyes that bleach more slowly, and the expression of one of the FRET pair genetically. PMID:26238052

  15. Study on spontaneous bursts of high voltage slow wave activities in electroencephalograms of the aged

    100 EEGs with bursts of high voltage slow wave activities (bursts) were found in 1150 of aged subjects sixty years and over. In these cases computerized cranial tomography (CT) examinations were carried out within 60 days of EEG recordings and CT findings (bursts CTs) were compared with those of 100 cases without bursts (control CTs). Another 100 consecutive CTs of cases with matched the age and the disease were used as the control. The results were as follows: 1) In bursts CTs, the incidence of normal findings was only 7%, while it was 18% in control CTs. The difference was statistically significant (p<0.001). 2) Brain atrophy was remarkable in bursts CTs. In bursts CT, the incidence of brain atrophy showed more than minor degree was 89%, while it was 64% in control CTs. The difference was statistically significant (p<0.001). 3) The incidences of periventricular lucency (PVL), enlargement of the inferior and posterior horn of the lateral ventricle, basal ganglia calcification observed on CT were significantly higher (55%, 39%, 12%) in bursts CTs than in control CTs (p<0.01, p<0.01, p<0.05). 4) The incidence of focal lesions was lower in bursts CTs than in control CTs. In paticular, large lesions were recognized in only 3% of bursts CTs, whereas those were noted in 15% of control CTs. The difference was statistically significant (p<0.01). 5) Small lesions were recognized in 21% of neurological normal patients with bursts, while they were found in 5% of these of control CTs. 6) Frontal and thalamic lesions were found more frequently in bursts CTs (26%, 13%) than in control CTs (21%, 8%), but the difference was not statistically significant. 7) The correlation between the side showing high voltage of bursts and the side with lesions observed on CT was good. In this way, it may be conceivable that appearance of bursts is not due to only focal lesions but results from generalized brain disfunction, such as aging and others. (author)

  16. Quantum capacitance: a microscopic derivation

    Mukherjee, Sreemoyee; MANNINEN, M; Deo, P. Singha

    2010-01-01

    We start from microscopic approach to many body physics and show the analytical steps and approximations required to arrive at the concept of quantum capacitance. These approximations are valid only in the semi-classical limit and the quantum capacitance in that case is determined by Lindhard function. The effective capacitance is the geometrical capacitance and the quantum capacitance in series, and this too is established starting from a microscopic theory.

  17. Active Power and DC-link Voltage Coordinative Control for Cascaded DC-AC Converter with Bidirectional Power Application

    Tian, Yanjun; Chen, Zhe; Deng, Fujin;

    2015-01-01

    Two stage cascaded converters are widely used in DC/AC hybrid systems to achieve the bidirectional power transmission. The topology of dual active bridge cascaded with inverter (DABCI) is commonly used in this application. This paper proposes a coordinative control method for DABCI and it’s able to...... reduce the DC-link voltage fluctuation between the DAB and inverter, then reduce the stress on the switching devices, as well as improve the system dynamic performance. In the proposed control method, the DAB and inverter are coordinated to control the DC-link voltage and the power, and this...... responsibility sharing control can effectively suppress the impact of the power variation on the DC-link voltage, without sacrificing stability. The proposed control method is also effective for DABCI in unidirectional power transmission. The effectiveness of the propose control has been validated by both...

  18. Active control of flying capacitor currents in multilevel voltage-source inverters

    Kokeš, Petr; Semerád, Radko

    2013-01-01

    Roč. 58, č. 4 (2013), s. 393-410. ISSN 0001-7043 Institutional support: RVO:61388998 Keywords : voltage source inverter (VSI) * multilevel inverter * flying capacitor Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  19. Active voltage contrast imaging of cross-sectional surface of multilayer ceramic capacitor using helium ion microscopy

    Sakai, C.; Ishida, N.; Masuda, H.; Nagano, S.; Kitahara, M.; Ogata, Y.; Fujita, D.

    2016-08-01

    We studied active voltage contrast (AVC) imaging using helium ion microscopy (HIM). We observed secondary electron (SE) images of the cross-sectional surface of multilayer ceramic capacitors (MLCCs) with and without a voltage applied to the internal electrodes. When no voltage was applied, we obtained an image reflecting the material contrast between the Ni internal electrode region and the BaTiO3 dielectric region of the cross-sectional surface of the MLCC. When a voltage was applied, the electrical potential difference between the grounded and the positively biased internal electrodes affected the contrast (voltage contrast). Moreover, attenuation of the SE intensity from the grounded to the positively biased internal electrodes was observed in the dielectric region. Kelvin probe force microscopy (KPFM) measurements of the contact potential difference (CPD) were performed on the same sample. By using the AVC image from the HIM observation and the CPD image from the KPFM measurement, we could quantitatively evaluate the electrical potential. We think that the results of this study will lead to an expansion in the number of applications of HIM.

  20. Arsenic removal from groundwater using low-cost carbon composite electrodes for capacitive deionization.

    Lee, Ju-Young; Chaimongkalayon, Nantanee; Lim, Jinho; Ha, Heung Yong; Moon, Seung-Hyeon

    2016-01-01

    Affordable carbon composite electrodes were developed to treat low-concentrated groundwater using capacitive deionization (CDI). A carbon slurry prepared using activated carbon powder (ACP), poly(vinylidene fluoride), and N-methyl-2-pyrrolidone was employed as a casting solution to soak in a low-cost porous substrate. The surface morphology of the carbon composite electrodes was investigated using a video microscope and scanning electron microscopy. The capacitance and electrical conductivity of the carbon composite electrodes were then examined using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), respectively. According to the CV and EIS measurements, the capacitances and electrical conductivities of the carbon composite electrodes were in the range of 8.35-63.41 F g(-1) and 0.298-0.401 S cm(-1), respectively, depending on ACP contents. A CDI cell was assembled with the carbon composite electrodes instead of with electrodes and current collectors. The arsenate removal test included an investigation of the optimization of several important operating parameters, such as applied voltage and solution pH, and it achieved 98.8% removal efficiency using a 1 mg L(-1) arsenate solution at a voltage of 2 V and under a pH 9 condition. PMID:27332854

  1. Control of Active Front-End Rectifier in Electric Drive under Unbalanced Voltage Supply

    Chomát, Miroslav; Schreier, Luděk; Bendl, Jiří

    Ponta Delgada - Azores: APDEE, 2011, s. 1-6. ISBN 978-972-8822-23-1. [Portuguese- Spanish Conference on Electrical Engineering - XII CLEEE /12./. Ponta Delgada - Azores (PT), 30.06.2011-02.07.2011] R&D Projects: GA ČR GA102/09/1273 Institutional research plan: CEZ:AV0Z20570509 Keywords : unbalanced voltage supply * DC-link voltage pulsations * pulse-width modulation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  2. Interface trap characterization and electrical properties of Au-ZnO nanorod Schottky diodes by conductance and capacitance methods

    Hussain, I.; Soomro, Muhammad Yousuf; Bano, Nargis; Nur, Omer; Willander, Magnus

    2012-01-01

    Schottky diodes with Au/ZnO nanorod (NR)/n-SiC configurations have been fabricated and their interface traps and electrical properties have been investigated by current-voltage (I-V), capacitance-voltage (C-V), capacitance-frequency (C-f), and conductance-frequency (G(p)/omega-omega) measurements. Detailed and systematic analysis of the frequency-dependent capacitance and conductance measurements was performed to extract the information about the interface trap states. The discrepancy between...

  3. A robust parasitic-insensitive successive approximation capacitance-to-digital converter

    Omran, Hesham

    2014-09-01

    In this paper, we present a capacitive sensor digital interface circuit using true capacitance-domain successive approximation that is independent of supply voltage. Robust operation is achieved by using a charge amplifier stage and multiple comparison technique. The interface circuit is insensitive to parasitic capacitances, offset voltages, and charge injection, and is not prone to noise coupling. The proposed design achieves very low temperature sensitivity of 25ppm/oC. A coarse-fine programmable capacitance array allows digitizing a wide capacitance range of 16pF with 12.5-bit quantization limited resolution in a compact area of 0.07mm2. The fabricated prototype is experimentally verified using on-chip sensor and off-chip MEMS capacitive pressure sensor. © 2014 IEEE.

  4. Cellular hyper-excitability caused by mutations that alter the activation process of voltage-gated sodium channels

    Mohamed-Yassine eAMAROUCH

    2015-02-01

    Full Text Available Voltage-gated sodium channels (Nav are widely expressed as macro-molecular complexes in both excitable and non-excitable tissues. In excitable tissues, the upstroke of the action potential is the result of the passage of a large and rapid influx of sodium ions through these channels. NaV dysfunction has been associated with an increasingly wide range of neurological, muscular and cardiac disorders. The purpose of this review is to summarize the recently identified sodium channel mutations that are linked to hyper-excitability phenotypes and associated with the alteration of the activation process of voltage gated sodium channels. Indeed, several clinical manifestations that demonstrate an alteration of tissue excitability were recently shown to be strongly associated with the presence of mutations that affect the activation process of the voltage-gated sodium channels. These emerging genotype-phenotype correlations have expanded the clinical spectrum of sodium channelopathies to include disorders which feature a hyper-excitability phenotype that may or may not be associated with a cardiomyopathy. The p.I141V mutation in SCN4A and SCN5A, as well as its homologous p.I136V mutation in SCN9A, are interesting examples of mutations that have been linked to inherited hyperexcitability myotonia, exercise-induced polymorphic ventricular arrhythmias and erythromelalgia, respectively. Regardless of which sodium channel isoform is investigated, the substitution of the isoleucine to valine in the locus 141 induces similar modifications in the biophysical properties of the voltage-gated sodium channels by shifting the voltage-dependence of steady state activation towards more negative potentials.

  5. The experiential fit of the capacitance-voltage characteristics of the AlGaN/AlN/GaN high electron mobility transistors%AlGaN/AlN/GaN高电子迁移率器件的电容电压特性的经验拟合

    王鑫华; 赵妙; 刘新宇; 蒲颜; 郑英奎; 魏珂

    2011-01-01

    利用蓝宝石衬底的AlGaN/AlN/GaN高电子迁移率器件(HEMT)的电容电压(C-V)特性,对电子费米能级与二维电子气面密度的经验关系进行表征,其结果对器件电荷控制模型的建立,跨导及电容表达式的简化有重要意义.文章创新性地提出参数α用于表征二维势阱对沟道电子限制能力,并认为α越小则二维势阱的沟道电子限制能力越强.利用上述经验关系来拟合电容,可以获得与实测电容很好的一致性.%This paper expresses the experiential relationship between Fermi level and the density of two-dimensional electron gas, based on the capacitance voltage (C-V) characteristics of the AlGaN/AlN/GaN high electron mobility transistor (HEMT) on sapphire substrate. The expression provides important references for establishing the device charge control model and simpliying the transconductance and capacitance. Parameter a is introduced for describing the ability for the two-dimensional potential well to restrict electrons, and we believe that the smaller the value of a, the stronger the restricting ability is. A coherent fitting effect, compared with the measurement, is obtained by making use of the experiential relationship said above.

  6. Measurements of Voltage Harmonics in 400 kV Transmission Network

    Ryszard Pawełek

    2014-06-01

    Full Text Available The paper deals with the analysis of voltage harmonics measurements performed in the 400 kV transmission network. The voltage was measured by means of three transducers: resistive voltage divider, inductive measuring transformer and capacitive voltage measuring transformer. Instrument errors were estimated for measuring transformers with reference to the harmonic values obtained from the voltage divider.

  7. Estimation of carrier mobility at organic semiconductor/insulator interface using an asymmetric capacitive test structure

    Rajesh Agarwal; Ashish K. Agarwal; Baquer Mazhari

    2016-01-01

    Mobility of carriers at the organic/insulator interface is crucial to the performance of organic thin film transistors. The present work describes estimation of mobility using admittance measurements performed on an asymmetric capacitive test structure. Besides the advantage of simplicity, it is shown that at low frequencies, the measured capacitance comes from a large area of channel making the capacitance-voltage characteristics insensitive to contact resistances. 2-D numerical simulation a...

  8. A Microscopic Capacitor Model of Voltage Coupling in Membrane Proteins: Gating Charge Fluctuations in Ci-VSD.

    Kim, Ilsoo; Warshel, Arieh

    2016-01-28

    The voltage sensitivity of membrane proteins is reflected in the response of the voltage sensing domains (VSDs) to the changes in membrane potential. This response is implicated in the displacement of positively charged residues, associated with the conformational changes of VSDs. The displaced charges generate nonlinear (i.e., voltage-dependent) capacitance current called the gating current (and its corresponding gating charge), which is a key experimental quantity that characterizes voltage activation in VSMP. However, the relevant theoretical/computational approaches, aimed to correlate the structural information on VSMP to electrophysiological measurements, have been rather limited, posing a broad challenge in computer simulations of VSMP. Concomitant with the development of our coarse-graining (CG) model of voltage coupling, we apply our theoretical framework for the treatments of voltage effects in membrane proteins to modeling the VSMP activation, taking the VSDs (Ci-VSD) derived from the Ciona intestinalis voltage sensitive phosphatase (Ci-VSP) as a model system. Our CG model reproduces the observed gating charge of Ci-VSD activation in several different perspectives. In particular, a new closed-form expression of the gating charge is evaluated in both nonequilibrium and equilibrium ways, while considering the fluctuation-dissipation relation that connects a nonequilibrium measurement of the gating charge to an equilibrium measurement of charge fluctuations (i.e., the voltage-independent linear component of membrane capacitance). In turn, the expression uncovers a novel link that connects an equilibrium measurement of the voltage-independent linear capacitance to a nonequilibrium measurement of the voltage-dependent nonlinear capacitance (whose integral over voltage is equal to the gating charge). In addition, our CG model yields capacitor-like voltage dependent free energy parabolas, resulting in the free energy difference and the free energy barrier for

  9. The hysteresis-free negative capacitance field effect transistors using non-linear poly capacitance

    Fan, S.-T.; Yan, J.-Y.; Lai, D.-C.; Liu, C. W.

    2016-08-01

    A gate structure design for negative capacitance field effect transistors (NCFETs) is proposed. The hysteresis loop in current-voltage performances is eliminated by the nonlinear C-V dependence of polysilicon in the gate dielectrics. Design considerations and optimizations to achieve the low SS and hysteresis-free transfer were elaborated. The effects of gate-to-source/drain overlap, channel length scaling, interface trap states and temperature impact on SS are also investigated.

  10. Finite element analysis of the macro fiber composite actuator: macroscopic elastic and piezoelectric properties and active control thereof by means of negative capacitance shunt circuit

    The finite element method (FEM) model of a piezoelectric macro fiber composite (MFC) is presented. Using a specially developed numerical model, the complete set of macroscopic values of elastic compliance and piezoelectric tensors is computed. These values are useful in numerical FEM simulations of more complex systems such as noise and vibration suppression devices or active acoustic metamaterials, where the MFC actuator can be approximated by a plate-like uniform piezoelectric material. Using this approach, a great reduction of the FEM model complexity can be achieved. The computed numerical macroscopic values of the MFC actuator are compared with MFC manufacturer's data and with data obtained using different computational methods. A demonstration of active tuning of effective elastic constants of the piezoelectric MFC actuator by means of a shunt electric circuit is presented. The effective material constants are computed using the FEM model developed. The effect of the shunt circuit capacitance on the effective anisotropic Young's moduli is analyzed in detail. A method for finding the proper shunt circuit adjustment that yields the maximum values of the MFC actuator Young's modulus is shown. Possible applications to noise and vibration suppression are discussed. (paper)

  11. Electronics drivers for high voltage dielectric electro active polymer (DEAP) applications

    Zhang, Zhe; Andersen, Michael A. E.

    2015-01-01

    both magnetic and piezoelectric transformers are employed for the heating valve and incremental motor application, where only ON/OFF regulation is adopted fo r energy saving; as for DEAP based energy harvesting, the no - isolated Buck/Boost converter is used, due to the system high power capacity...... (above 100W), but the voltage balancing across the series - connected high voltage IGBTs is a critical issue and accordi ngly a novel gate driver circuitry is proposed and equipped; due to the requirements of the audio products, such as low distortion and noise, the multi - level Buck converter based...

  12. Nanoscale capacitance imaging with attofarad resolution using ac current sensing atomic force microscopy

    Nanoscale capacitance imaging with attofarad resolution (∼1 aF) of a nano-structured oxide thin film, using ac current sensing atomic force microscopy, is reported. Capacitance images are shown to follow the topographic profile of the oxide closely, with nanometre vertical resolution. A comparison between experimental data and theoretical models shows that the capacitance variations observed in the measurements can be mainly associated with the capacitance probed by the tip apex and not with positional changes of stray capacitance contributions. Capacitance versus distance measurements further support this conclusion. The application of this technique to the characterization of samples with non-voltage-dependent capacitance, such as very thin dielectric films, self-assembled monolayers and biological membranes, can provide new insight into the dielectric properties at the nanoscale

  13. TCAD simulations of High-Voltage-CMOS Pixel structures for the CLIC vertex detector

    Buckland, Matthew Daniel

    2016-01-01

    The requirements for precision physics and the experimental conditions at CLIC result in stringent constraints for the vertex detector. Capacitively coupled active pixel sensors with 25 μm pitch implemented in a commercial 180 nm High-Voltage CMOS (HV-CMOS) process are currently under study as a candidate technology for the CLIC vertex detector. Laboratory calibration measurements and beam tests with prototypes are complemented by detailed TCAD and electronic circuit simulations, aiming for a comprehensive understanding of the signal formation in the HV-CMOS sensors and subsequent readout stages. In this note 2D and 3D TCAD simulation results of the prototype sensor, the Capacitively Coupled Pixel Detector version three (CCPDv3), will be presented. These include the electric field distribution, leakage current, well capacitance, transient response to minimum ionising particles and charge-collection.

  14. Energy consumption and constant current operation in membrane capacitive deionization

    Zhao, R.; Biesheuvel, P. M.; Wal, van der, A.C.

    2012-01-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a cell voltage between two oppositely placed porous electrodes sandwiching a spacer channel that transports the water to be desalinated. In the salt removal step, ions are adsorbed at the carbon–water interface within the micropores inside the porous electrodes. After the electrodes reach a certain adsorption capacity, the cell voltage is reduced or even reversed, which leads to ion release from the e...

  15. Mapping Capacitive Coupling Among Pixels in a Sensor Array

    Seshadri, Suresh; Cole, David M.; Smith, Roger M.

    2010-01-01

    An improved method of mapping the capacitive contribution to cross-talk among pixels in an imaging array of sensors (typically, an imaging photodetector array) has been devised for use in calibrating and/or characterizing such an array. The method involves a sequence of resets of subarrays of pixels to specified voltages and measurement of the voltage responses of neighboring non-reset pixels.

  16. Low voltage driven dielectric electro active polymer actuator with integrated piezoelectric transformer based driver

    Andersen, Thomas; Rødgaard, Martin Schøler; Thomsen, Ole Cornelius;

    2011-01-01

    actuators, a low voltage solution is developed by integrating the driver electronic into a 110 mm tall cylindrical coreless Push InLastor actuator. To decrease the size of the driver, a piezoelectric transformer (PT) based solution is utilized. The PT is essentially an improved Rosen type PT...

  17. Analysis of Dielectric Electro Active Polymer Actuator and its High Voltage Driving Circuits

    Thummala, Prasanth; Huang, Lina; Zhang, Zhe;

    2012-01-01

    actuator is analyzed in detail and the actuator structures, for the wind turbine flap and the heating valve applications are shown. Different high voltage switch mode power supply topologies for driving the DEAP actuator are discussed. The simulation and experimental results are discussed....

  18. Design of Excitation Capacitance for Self-Excited Induction Generator

    Swati Devabhaktuni

    2011-12-01

    Full Text Available This paper presents simple and accurate approach to compute the minimum value of capacitance required for initiating the voltage build-up in a three-phase selfexcited induction generator. Based on the steady-state equivalent circuit model different numerical methods for solving frequency are known from previous literature, which are of 6th order polynomial. In this paper the order of the polynomial is reduced to the 4thorder frequency with a new, simple and direct method is developed to find the capacitance requirement. Critical values of the impedance and speed, below which the machine fails to self excite irrespective of the capacitance used, are found to exist. Closed form solutions for capacitance are derived for no-load and RL loads. Experimental results obtained on a 3.5kW induction machine confirm the feasibility and accuracy of the proposed method.

  19. Segmented Capacitance Sensor with Partially Released Inactive Segments

    Lev Jakub

    2015-09-01

    Full Text Available Material throughput measurement is important for many applications, for example yield maps creation or control of mass flow in stationary lines. Quite perspective can be the capacitive throughput method. Segmented capacitance sensor (SCS is discussed in this paper. SCS is a compromise between simple capacitive throughput sensors and electrical capacitance tomography sensors. The SCS variant with partially released inactive segments is presented. The mathematical model of SCS was created and verified by measurements. A good correspondence between measured and computed values was found and it can be stated that the proposed mathematical model was verified. During measurement the voltage values on the inactive segments were monitored as well. On the basis of the measurement there was found that these values are significantly influenced by material distribution.

  20. Control strategy for three-phase four-wire PWM converter of integrated voltage compensation type active SFCL

    The integrated voltage compensation type active superconducting fault current limiter (SFCL) is composed of three air-core superconducting transformers and a three-phase four-wire PWM converter. In order to realize the current-limiting characteristics of the integrated active SFCL, it is needed to control the three-phase four-wire PWM converter flexibly and reasonably. Thereby, the control strategy for the converter is analyzed in this paper. In dq0 reference frame, the mathematical model of the converter is founded. The double-loop control strategy, consisting of voltage outer loop and current inner loop, is presented. Moreover, the voltage balance control for the split DC link capacitors is also considered. Using MATLAB, the simulation model of the integrated active SFCL is built. According to the simulation results, it is known that, the presented control strategy is feasible and valid, and the converter can work well under unsymmetrical and symmetrical fault conditions, and then the fault current can be limited quickly and effectively.

  1. A Transformerless Hybrid Active Filter Capable of Complying with Harmonic Guidelines for Medium-Voltage Motor Drives

    Kondo, Ryota; Akagi, Hirofumi

    This paper presents a transformerless hybrid active filter that is integrated into medium-voltage adjustable-speed motor drives for fans, pumps, and compressors without regenerative braking. The authors have designed and constructed a three-phase experimental system rated at 400V and 15kW, which is a downscaled model from a feasible 6.6-kV 1-MW motor drive system. This system consists of the hybrid filter connecting a passive filter tuned to the 7th harmonic filter in series with an active filter that is based on a three-level diode-clamped PWM converter, as well as an adjustable-speed motor drive in which a diode rectifier is used as the front end. The hybrid filter is installed on the ac side of the diode rectifier with no line-frequency transformer. The downscaled system has been exclusively tested so as to confirm the overall compensating performance of the hybrid filter and the filtering performance of a switching-ripple filter for mitigating switching-ripple voltages produced by the active filter. Experimental results verify that the hybrid filter achieves harmonic compensation of the source current in all the operating regions from no-load to the rated-load conditions, and that the switching-ripple filter reduces the switching-ripple voltages as expected.

  2. A Rain Gauge System using a Capacitance Sensor

    Worawat Sa-Ngiamvibool

    2013-08-01

    Full Text Available This paper proposes a rain gauge system using a coaxial capacitance sensor. The proposed system consists of a high-pass filter, a coaxial capacitance sensor, SMS module, a microcontroller and a smartphone. The sensor capacitance is proportional to the rainfall levels. It is converted into voltage signal. The corresponding voltage signal is sent to the microcontroller for converting the signal levels to the rainfall levels in millimetres. The microcontroller sends the rainfall levels to the SMS module that then sends the rainfall level data to show on the display screen of the smartphone. The experimentalresults showed that the proposed prototype can provide the correct data compared to the traditional system.

  3. Membrane capacitive deionization

    Biesheuvel, P.M.; Wal, van der A.

    2010-01-01

    Membrane capacitive deionization (MCDI) is an ion-removal process based on applying an electrical potential difference across an aqueous solution which flows in between oppositely placed porous electrodes, in front of which ion-exchange membranes are positioned. Due to the applied potential, ions ar

  4. Digital capacitance measuring system

    1973-01-01

    The hardware phase of a digital capacitance measuring system is presented with the major emphasis placed on the electrical design and operation. Test results are included of the three units fabricated. The system's interface is applicable to existing requirements for the space shuttle vehicle.

  5. Intrinsic oscillatory activity arising within the electrically coupled AII amacrine-ON cone bipolar cell network is driven by voltage-gated Na + channels

    Trenholm, S; Borowska, J; Zhang, J; Hoggarth, A; Johnson, K.; Barnes, S.; Lewis, TJ; Awatramani, GB

    2012-01-01

    In the rd1 mouse model for retinal degeneration, the loss of photoreceptors results in oscillatory activity (∼10-20 Hz) within the remnant electrically coupled network of retinal ON cone bipolar and AII amacrine cells. We tested the role of hyperpolarization-activated currents (I h), voltage-gated Na + channels and gap junctions in mediating such oscillatory activity. Blocking I h (1 mm Cs +) hyperpolarized the network and augmented activity, while antagonizing voltage-dependent Na + channels...

  6. Optimizing growth and post treatment of diamond for high capacitance neural interfaces.

    Tong, Wei; Fox, Kate; Zamani, Akram; Turnley, Ann M; Ganesan, Kumaravelu; Ahnood, Arman; Cicione, Rosemary; Meffin, Hamish; Prawer, Steven; Stacey, Alastair; Garrett, David J

    2016-10-01

    Electrochemical and biological properties are two crucial criteria in the selection of the materials to be used as electrodes for neural interfaces. For neural stimulation, materials are required to exhibit high capacitance and to form intimate contact with neurons for eliciting effective neural responses at acceptably low voltages. Here we report on a new high capacitance material fabricated using nitrogen included ultrananocrystalline diamond (N-UNCD). After exposure to oxygen plasma for 3 h, the activated N-UNCD exhibited extremely high electrochemical capacitance greater than 1 mF/cm(2), which originates from the special hybrid sp(2)/sp(3) structure of N-UNCD. The in vitro biocompatibility of the activated N-UNCD was then assessed using rat cortical neurons and surface roughness was found to be critical for healthy neuron growth, with best results observed on surfaces with a roughness of approximately 20 nm. Therefore, by using oxygen plasma activated N-UNCD with appropriate surface roughness, and considering the chemical and mechanical stability of diamond, the fabricated neural interfaces are expected to exhibit high efficacy, long-term stability and a healthy neuron/electrode interface. PMID:27424214

  7. Multilevel inverter based class D audio amplifier for capacitive transducers

    Nielsen, Dennis; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    The reduced semiconductor voltage stress makes the multilevel inverters especially interesting, when driving capacitive transducers for audio applications. A ± 300 V flying capacitor class D audio amplifier driving a 100 nF load in the midrange region of 0.1-3.5 kHz with Total Harmonic Distortion...

  8. Optimization of salt adsorption rate in membrane capacitive deionization

    Zhao, R.; Satpradit, O.A.; Rijnaarts, H.; Biesheuvel, P.M.; Wal, van der A.

    2013-01-01

    Membrane capacitive deionization (MCDI) is a water desalination technique based on applying a cell voltage between two oppositely placed porous electrodes sandwiching a spacer channel that transports the water to be desalinated. In MCDI, ion-exchange membranes are positioned in front of each porous

  9. Energy consumption and constant current operation in membrane capacitive deionization

    Zhao, R.; Biesheuvel, P.M.; Wal, van der A.F.

    2012-01-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a cell voltage between two oppositely placed porous electrodes sandwiching a spacer channel that transports the water to be desalinated. In the salt removal step, ions are adsorbed at the carbon–water interf

  10. Non-contact measurement of dc voltages using nonlinear elements

    In this work, it is shown that dc voltages may be measured via a capacitive interface, provided that the capacitance between the measurement system and the dc voltage source being measured is nonlinearized. This nonlinearization is achieved by the addition of a nonlinear capacitor in series with the coupling capacitance. Two types of nonlinear capacitor are used—multilayer ceramics and varicap diodes. Currently available multilayer ceramics have a larger value than desired but prove the concept, while the small capacitance of the varicap diode allows measurement on real wires. Results show that over a low voltage range (−8 V to +8 V), the voltage on a conductor can be measured if the coupling capacitance between source and electrode is larger than 20 pF, which equates to an electrode length of 5 cm when wire compliant with MIL-W-81044-22 is used. Detection is performed by momentarily applying a voltage at a node within the measurement system, then measuring the time it takes for this voltage to decay to a threshold level—the capacitive nonlinearity causes this time delay to be dependent upon the dc input voltage whose value is being measured. (paper)

  11. Carbon nanofiber supercapacitors with large areal capacitances

    McDonough, James R.

    2009-01-01

    We develop supercapacitor (SC) devices with large per-area capacitances by utilizing three-dimensional (3D) porous substrates. Carbon nanofibers (CNFs) functioning as active SC electrodes are grown on 3D nickel foam. The 3D porous substrates facilitate a mass loading of active electrodes and per-area capacitance as large as 60 mg/ cm2 and 1.2 F/ cm2, respectively. We optimize SC performance by developing an annealing-free CNF growth process that minimizes undesirable nickel carbide formation. Superior per-area capacitances described here suggest that 3D porous substrates are useful in various energy storage devices in which per-area performance is critical. © 2009 American Institute of Physics.

  12. Switch-mode High Voltage Drivers for Dielectric Electro Active Polymer (DEAP) Incremental Actuators

    Thummala, Prasanth

    , a new bidirectional flyback converter topology with multiple series connected outputs is proposed. A theoretical comparison showed that the proposed converter could improve the overall energy efficiency, lower the cost and reduce the volume of high voltage driver. Key words: high voltage, switch......-to-stroke implications of conventional linear actuators, where the stroke is limited by their size. In incremental mode, DEAP actuators are several orders of magnitude shorter in their length compared to the stroke/elongation they provide. The dissertation presents design, control and implementation of switch-mode high...... and non-sectioned, interleaved and non-sectioned, non-interleaved and sectioned, and interleaved and sectioned have been investigated and implemented. A digital control technique to achieve the valley switching (variable frequency control) during both charge and discharge operations in a bidirectional...

  13. Highly capacitance-enhanced activated carbons by oxidation-activation treatments for supercapacitor applications%氧化-活化处理的超级电容器用高比电容活性炭

    朱晨; 张远亮; 刘洪涛

    2012-01-01

    Highly capacitance-enhanced activated carbons used for supercapacitors were obtained by treatment of low-cost granular activated carbons. The preferred technical process involves pre-oxidation and acidic or alkaline activation treatment. It is shown with the combination of IR spectra and N2 adsorption-desorption isotherms that the pre-oxidation treatment is beneficial to opening closed pores and raises the effective pore capacity, but has few effects on the increase of carbon surface functional groups. The mixed acid (3H3PO4+H2SO4) or alkali (KOH) treatment evidently fertilizes electroactive functional groups at the carbon surface. Meanwhile, the specific surface area of activated carbon is greatly increased. The capacitive behavior of the treated activated carbon is investigated by a.c. impedance, cyclic voltammetry, and galvanostatic charge-discharge measurements. The result shows that the pre-oxidation-activation treated activated carbon has low charge-transfer resistance, large electrochemical capacitance, and stable cycle life. Especially, the specific capacitance of the pre-oxidation-acidic activation treated activated activated carbon (POAC_A) and the pre-oxidation-alkaline activation treated activated activated carbon (POAC_B) at the charge-discharge current of 1.0 A/g reach 187 F/g and 206 F/g, respectively.%通过对普通颗粒活性炭采取不同优化工艺处理,发现经空气预氧化后,再用混合酸(磷酸+硫酸)或氢氧化钾进行活化处理,可得到高比电容超级电容器用活性炭.红外光谱和氮吸脱附分析表明:预氧化处理并没有明显增加其表面官能团,但有利于疏通孔道,提高活性炭的有效孔容积;混酸和强碱活化处理明显丰富活性炭的表面电活性基团,并且增大材料的比表面积.采用交流阻抗、循环伏安、恒流充放电等电化学方法对活化材料进行超级电容行为测试,表明经氧化-活化处理的活性炭电极传荷阻抗小、电容特

  14. Mefenamic acid as a novel activator of L-type voltage-dependent Ca2+ channels in smooth muscle cells from pig proximal urethra

    Teramoto, Noriyoshi; Tomoda, Toshihisa; Ito, Yushi

    2005-01-01

    The effects of mefenamic acid and Bay K 8644 on voltage-dependent nifedipine-sensitive inward Ba2+ currents in pig urethral myocytes were investigated by use of conventional whole-cell configuration patch clamp.Mefenamic acid increased the peak amplitude of voltage-dependent nifedipine-sensitive inward Ba2+ current without shifting the position of the current–voltage relationship.Mefenamic acid (300 μM) caused little shift in the activation curve although the voltage dependence of the steady-...

  15. Barbiturates inhibit ATP-K+ channels and voltage-activated currents in CRI-G1 insulin-secreting cells.

    Kozlowski, R. Z.; Ashford, M. L.

    1991-01-01

    1. Patch-clamp recording techniques were used to examine the effects of barbiturates upon the ATP-K+ channel, and voltage-activated channels present in the plasma membrane of CRI-G1 insulin-secreting cells. 2. Thiopentone inhibited ATP-K+ channel activity when applied to cell-attached patches or the intracellular or extracellular surface of cell-free patches. Secobarbitone and pentobarbitone were also effective inhibitors of ATP-K+ channels in cell-free patches, whereas phenobarbitone was ine...

  16. Enhancement in ion adsorption rate and desalination efficiency in a capacitive deionization cell through improved electric field distribution using electrodes composed of activated carbon cloth coated with zinc oxide nanorods.

    Laxman, Karthik; Myint, Myo Tay Zar; Bourdoucen, Hadj; Dutta, Joydeep

    2014-07-01

    Electrodes composed of activated carbon cloth (ACC) coated with zinc oxide (ZnO) nanorods are compared with plain ACC electrodes, with respect to their desalination efficiency of a 17 mM NaCl solution at different applied potentials. Polarization of the ZnO nanorods increased the penetration depth and strength of the electric field between the electrodes, leading to an increase in the capacitance and charge efficiency at reduced input charge ratios. Uniform distribution of the electric field lines between two electrodes coated with ZnO nanorods led to faster ion adsorption rates, reduced the electrode saturation time, and increased the average desalination efficiency by ∼45% for all applied potentials. The electrodes were characterized for active surface area, capacitance from cyclic voltammetry, theoretical assessment of surface area utilization, and the magnitude of electric field force acting on an ion of unit charge for each potential. PMID:24940607

  17. Improved circuit for measuring capacitive and inductive reactances

    Dalins, I.; Mc Carty, V.

    1967-01-01

    Amplifier circuit measures very small changes of capacitive or inductive reactance, such as produced by a variable capacitance or a variable inductance displacement transducer. The circuit employs reactance-sensing oscillators in which field effect transistors serve as the active elements.

  18. Ion channels, phosphorylation and mammalian sperm capacitation

    Pablo E Visconti; Dario Krapf; José Luis de la Vega-Beltrán; Juan José Acevedo; Alberto Darszon

    2011-01-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies.

  19. Influence of activated carbon loading on the deionization performance of electrode capacitance%活性炭负载量对电极电容去离子性能的影响

    肖书彬; 徐克; 阮国岭

    2012-01-01

    Increasing the specific surface area is a method for improving the capacitance deionization efficiency. Based on the study of the effect of activated carbon loading on electrode specific surface area,a kind of efficient method for improving the deionizaion performance of carbon electrode is discussed. The experimental results show that increasing the loading of activated carbon can effectively improve the specific surface area of electrodes. The electrode capacitance can be as high as 0.56 F/cm2, showing good capacitance deionication performance. Although increasing activated carbon substances continuously does not have much influence on the resistance inside the electrode, it is impossible to make further improvement on the adsorptive surface of the electrode. The specific capacitance declines suddenly and sharply. Optimizing the pore structure of electrodes is an effective method for improving the electro-adsorptive capacity of activated carbon electrodes.%增大电极比表面积是提高电容去离子效率的方法之一.通过研究活性炭负载量对电极比表面积的影响,探讨了一种提升炭电极电容去离子性能的有效方法.实验结果表明,增加活性炭负载量可有效提升电极比表面积,电极电容最高可达0.56 F/cm2,表现出较好的电容去离子性能.持续增加活性物质虽对电极内电阻影响较小,但不能进一步提高电极吸附表面,比电容急剧下降.优化电极孔隙结构是提升活性炭电极电吸附性能的有效方法.

  20. Blockade by sigma site ligands of high voltage-activated Ca2+ channels in rat and mouse cultured hippocampal pyramidal neurones.

    Church, J; Fletcher, E. J.

    1995-01-01

    1. The effects of a series of structurally-dissimilar sigma site ligands were examined on high voltage-activated Ca2+ channel activity in two preparations of cultured hippocampal pyramidal neurones. 2. In mouse hippocampal neurones under whole-cell voltage-clamp, voltage-activated Ca2+ channel currents carried by barium ions (IBa) were reduced with the rank order (IC50 values in microM): 1S,2R-(-)-cis-N-methyl-N-[2-(3,4-dichlorophenyl)ethyl]- 2-(1-pyrrolidinyl)cyclohexylamine (7.8) > rimcazol...

  1. Self-Nulling Lock-in Detection Electronics for Capacitance Probe Electrometer

    Blaes, Brent R.; Schaefer, Rembrandt T.

    2012-01-01

    A multi-channel electrometer voltmeter that employs self-nulling lock-in detection electronics in conjunction with a mechanical resonator with noncontact voltage sensing electrodes has been developed for space-based measurement of an Internal Electrostatic Discharge Monitor (IESDM). The IESDM is new sensor technology targeted for integration into a Space Environmental Monitor (SEM) subsystem used for the characterization and monitoring of deep dielectric charging on spacecraft. Use of an AC-coupled lock-in amplifier with closed-loop sense-signal nulling via generation of an active guard-driving feedback voltage provides the resolution, accuracy, linearity and stability needed for long-term space-based measurement of the IESDM. This implementation relies on adjusting the feedback voltage to drive the sense current received from the resonator s variable-capacitance-probe voltage transducer to approximately zero, as limited by the signal-to-noise performance of the loop electronics. The magnitude of the sense current is proportional to the difference between the input voltage being measured and the feedback voltage, which matches the input voltage when the sense current is zero. High signal-to-noise-ratio (SNR) is achieved by synchronous detection of the sense signal using the correlated reference signal derived from the oscillator circuit that drives the mechanical resonator. The magnitude of the feedback voltage, while the loop is in a settled state with essentially zero sense current, is an accurate estimate of the input voltage being measured. This technique has many beneficial attributes including immunity to drift, high linearity, high SNR from synchronous detection of a single-frequency carrier selected to avoid potentially noisy 1/f low-frequency spectrum of the signal-chain electronics, and high accuracy provided through the benefits of a driven shield encasing the capacitance- probe transducer and guarded input triaxial lead-in. Measurements obtained from a

  2. An ultra-small capacitance Josephson junction

    We consider a voltage biased ultra-small capacitance Josephson junction, with the coupling to the external source containing both resistive and inductive elements. In addition we include a phenomenological coupling to an external heat bath. Our goal is to extend and generalize previous studies of current biased ultra-small junctions. Charging effects, due to the presence of discrete charge carriers in the junction, play a crucial role. In particular we find an infinite resistance branch in the I-V characteristic for a d.c. bias, and resistive steps in the I-V curve when the external bias contains an additional a.c. component. These effects are reminiscent of the 'Coulomb blockade' and the inverse Shapiro steps, respectively, predicted earlier in the context of current biased circuits. As a response to an a.c. voltage bias we also predict spikes of the voltage across the junction and a noisy background, when this voltage is plotted as a function of either the external d.c. biasing voltage or the external frequency. Our analysis shows that various circuitry components may qualitatively affect the response of the junction to an external bias. (authors)

  3. VOLTAGE REGULATORS ASYNCHRONOUS GENERATORS

    Grigorash O. V.

    2015-06-01

    Full Text Available A promising is currently the use of asynchronous generators with capacitive excitation as a source of electricity in stand-alone power systems. Drive asynchronous generators may exercise as a thermal engine and wind wheel wind power plant or turbines of small hydropower plants. The article discusses the structural and schematics of voltage stabilizers and frequency of asynchronous generators with improved operational and technical specifications. Technical novelty of design solutions of the magnetic system and stabilizers asynchronous generator of electricity parameters confirmed by the patents for the invention of the Russian Federation. The proposed technical solution voltage stabilizer asynchronous generators, can reduce the weight of the block capacitors excitation and reactive power compensation, as well as to simplify the control system power circuit which has less power electronic devices. For wind power plants it is an important issue not only to stabilize the voltage of the generator, but also the frequency of the current. Recommend functionality stabilizer schemes parameters of electric power made for direct frequency converters with artificial and natural switching power electronic devices. It is also proposed as part of stabilization systems use single-phase voltage, three-phase transformers with rotating magnetic field, reduce the level of electromagnetic interference generated by power electronic devices for switching, enhance the efficiency and reliability of the stabilizer.

  4. Induced Charge Capacitive Deionization

    Rubin, S; Biesheuvel, P M; Bercovici, M

    2016-01-01

    We demonstrate the phenomenon of induced-charge capacitive deionization (ICCDI) that occurs around a porous and conducting particle immersed in an electrolyte, under the action of an external electrostatic field. The external electric field induces an electric dipole in the porous particle, leading to capacitive charging of its volume by both cations and anions at opposite poles. This regime is characterized both by a large RC charging time and a small electrochemical charge relaxation time, which leads to rapid and significant deionization of ionic species from a volume which is on the scale of the particle. We show by theory and experiment that the transient response around a cylindrical particle results in spatially non-uniform charging and non-steady growth of depletion regions which emerge around the particle's poles. Potentially, ICCDI can be useful in applications where fast concentration changes of ionic species are required over large volumes.

  5. A high performance, variable capacitance accelerometer

    Wilner, L. Bruce

    1988-12-01

    A variable capacitance acceleration sensor is described. Manufactured using silicon microfabrication techniques, the sensor uses a midplane, flat plate suspension, gas damping, and overrange stops. The sensor is assembled from three silicon wafers, using anodic bonds to inlays of borosilicate glass. Typical sensor properties are 7-pF active capacitance, 3-pF tare capacitance, a response of 0.05 pF/G, a resonance frequency of 3.4 kHz, and damping 0.7 critical. It is concluded that this sensor, with appropriate electronics, forms an accelerometer with an order-of-magnitude greater sensitivity-bandwidth product than a comparable piezoresistive acclerometer, and with extraordinary shock resistance.

  6. High-voltage pulse generator for electron gun power supply

    High-voltage pulse generator with combined capacitive and inductive energy storages for electron gun power supply is described. Hydrogen thyratron set in a short magnetic lense is a current breaker. Times of current interruption in thyratrons are in the range from 100 to 300 ns. With 1 kV charging voltage of capacitive energy storage 25 kV voltage pulse is obtained in the load. The given high-voltage pulse generator was used for supply of an electron gun generating 10-30 keV low-energy electron beam

  7. Molecular Aspects of Capacitation

    Gulfidan Zulfikaroglu; Hulya Ozgur; Sait Polaturkey

    2010-01-01

    Male and female gamets are derived from the primordial germ cells, which migrate from the wall of the yolk sac toward the developing gonads. Following a series of mitotic divisions these cells increase in number at the gonads. The primordial germ cells differentiate into spermatogonia and take the form of mature spermatozoa after spermotogensis and spermotogenesis at puberty. Capacitation is the reaction, which includes all of the molecular and physiological events of mature sperm to gain the...

  8. Capacitance of graphene nanoribbons

    Shylau, A. A.; Klos, J. W.; Zozoulenko, I. V.

    2009-01-01

    We present an analytical theory for the gate electrostatics and the classical and quantum capacitance of the graphene nanoribbons (GNRs) and compare it with the exact self-consistent numerical calculations based on the tight-binding p-orbital Hamiltonian within the Hartree approximation. We demonstrate that the analytical theory is in a good qualitative (and in some aspects quantitative) agreement with the exact calculations. There are however some important discrepancies. In order to underst...

  9. Capacitance probe for detection of anomalies in non-metallic plastic pipe

    Mathur, Mahendra P.; Spenik, James L.; Condon, Christopher M.; Anderson, Rodney; Driscoll, Daniel J.; Fincham, Jr., William L.; Monazam, Esmail R.

    2010-11-23

    The disclosure relates to analysis of materials using a capacitive sensor to detect anomalies through comparison of measured capacitances. The capacitive sensor is used in conjunction with a capacitance measurement device, a location device, and a processor in order to generate a capacitance versus location output which may be inspected for the detection and localization of anomalies within the material under test. The components may be carried as payload on an inspection vehicle which may traverse through a pipe interior, allowing evaluation of nonmetallic or plastic pipes when the piping exterior is not accessible. In an embodiment, supporting components are solid-state devices powered by a low voltage on-board power supply, providing for use in environments where voltage levels may be restricted.

  10. Anomalous capacitance characteristics of TFTs with LDD structures in the saturation region

    The effect of lightly doped drain (LDD) doping concentration on the capacitance of a low-temperature polycrystalline silicon (LTPS) thin-film transistor (TFT) is investigated. An anomalous gate-to-source capacitance phenomenon is observed: first, the capacitance decreases, and then it increases according to the gate voltage in the saturation region. This phenomenon is not affected by the subgap density-of-states and arises as the doping concentration of the LDD region is reduced. To investigate the effects of each source and the drain LDD dose on the gate-to-source capacitance, two-dimensional device simulations were conducted in which each dose of the source and drain LDD was changed individually. The reduced controllability of the source voltage to the gate charge in the saturation region due to the increased resistance of the source LDD region with low LDD dose is identified as the reason for this anomalous capacitance phenomenon. (paper)

  11. Anomalous capacitance characteristics of TFTs with LDD structures in the saturation region

    Kim, Miryeon; Sun, Wookyung; Shin, Minho; Kim, Kiwoo; Kang, Jongseuk; Shin, Hyungsoon

    2016-05-01

    The effect of lightly doped drain (LDD) doping concentration on the capacitance of a low-temperature polycrystalline silicon (LTPS) thin-film transistor (TFT) is investigated. An anomalous gate-to-source capacitance phenomenon is observed: first, the capacitance decreases, and then it increases according to the gate voltage in the saturation region. This phenomenon is not affected by the subgap density-of-states and arises as the doping concentration of the LDD region is reduced. To investigate the effects of each source and the drain LDD dose on the gate-to-source capacitance, two-dimensional device simulations were conducted in which each dose of the source and drain LDD was changed individually. The reduced controllability of the source voltage to the gate charge in the saturation region due to the increased resistance of the source LDD region with low LDD dose is identified as the reason for this anomalous capacitance phenomenon.

  12. Voltage- and current-activated metal–insulator transition in VO2-based electrical switches: a lifetime operation analysis

    Aurelian Crunteanu, Julien Givernaud, Jonathan Leroy, David Mardivirin, Corinne Champeaux, Jean-Christophe Orlianges, Alain Catherinot and Pierre Blondy

    2010-01-01

    Full Text Available Vanadium dioxide is an intensively studied material that undergoes a temperature-induced metal–insulator phase transition accompanied by a large change in electrical resistivity. Electrical switches based on this material show promising properties in terms of speed and broadband operation. The exploration of the failure behavior and reliability of such devices is very important in view of their integration in practical electronic circuits. We performed systematic lifetime investigations of two-terminal switches based on the electrical activation of the metal–insulator transition in VO2 thin films. The devices were integrated in coplanar microwave waveguides (CPWs in series configuration. We detected the evolution of a 10 GHz microwave signal transmitted through the CPW, modulated by the activation of the VO2 switches in both voltage- and current-controlled modes. We demonstrated enhanced lifetime operation of current-controlled VO2-based switching (more than 260 million cycles without failure compared with the voltage-activated mode (breakdown at around 16 million activation cycles. The evolution of the electrical self-oscillations of a VO2-based switch induced in the current-operated mode is a subtle indicator of the material properties modification and can be used to monitor its behavior under various external stresses in sensor applications.

  13. Nonlinear dynamics of capacitive charging and desalination by porous electrodes.

    Biesheuvel, P M; Bazant, M Z

    2010-03-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by supercapacitors, water desalination and purification by capacitive deionization, and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) valid in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory for the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes with different time scales: (i) in the "supercapacitor regime" of small voltages and/or early times, the porous electrode acts like a transmission line, governed by a linear diffusion equation for the electrostatic potential, scaled to the RC time of a single pore, and (ii) in the "desalination regime" of large voltages and long times, the porous electrode slowly absorbs counterions, governed by coupled, nonlinear diffusion equations for the pore-averaged potential and salt concentration. PMID:20365735

  14. Modeling and experimental testing activity of the Voltage Optimization Unit

    Zecchino, Antonio; Hu, Junjie; Marinelli, Mattia

    In the EUDP project ‘Energy saving by voltage management’ two reports are provided by Technical University of Denmark (DTU) covering the simulation studies and experimental work. The first report presented the simulation results regarding the technical evaluation of on-load tap changers in solving...... and distributed power systems, located at DTU Risø campus. The experimental test validates the control performance of the OLTC transformer and the test indicates that, using remote measurement, the voltage of the system can be kept in a safe operational band. However, the remote measurement implies additional...... cost investments of to the system operator, thus a proactive tap algorithm is developed and tested in this project, relying on local measurements. In addition, we also compared the experimental result with the one simulated in the DigSilent PowerFactory software environment (the software used...

  15. A Three Phase Four Wire Shunt Active Power Filter Control Algorithm under Unbalanced and Distorted Supply Voltage

    K.Srinivas

    2014-03-01

    Full Text Available In this paper a control algorithm is validated with simulation studies in MAT environment and experimental studies are performed in to validate the proposed control algorithm. The projected algorithm to compensate the nonlinear and loads in three phase four wire distribution system using shunt active power filter. In this algorithm a positive sequence extraction of the supply voltage and the theory of instantaneous symmetrical component. To exemplify the concept, a three phase four wire with unbalance and non linear load is considered for compensation and detailed simulation and experimental studies are presented.

  16. Actions of arginine polyamine on voltage and ligand-activated whole cell currents recorded from cultured neurones.

    Scott, R. H.; Sweeney, M. I.; Kobrinsky, E. M.; Pearson, H. A.; Timms, G. H.; Pullar, I A; Wedley, S.; Dolphin, A. C.

    1992-01-01

    1. Toxins from invertebrates have proved useful tools for investigation of the properties of ion channels. In this study we describe the actions of arginine polyamine which is believed to be a close analogue of FTX, a polyamine isolated from the American funnel web spider, Agelenopsis aperta. 2. Voltage-activated Ca2+ currents and Ca(2+)-dependent Cl- currents recorded from rat cultured dorsal root ganglion neurones were reversibly inhibited by arginine polyamine (AP; 0.001 to 100 microM). Lo...

  17. E-beam high voltage switching power supply

    A high power, solid state power supply is described for producing a controllable, constant high voltage output under varying and arcing loads suitable for powering an electron beam gun or other ion source. The present power supply is most useful for outputs in a range of about 100-400 kW or more. The power supply is comprised of a plurality of discrete switching type dc-dc converter modules, each comprising a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, and an output rectifier for producing a dc voltage at the output of each module. The inputs to the converter modules are fed from a common dc rectifier/filter and are linked together in parallel through decoupling networks to suppress high frequency input interactions. The outputs of the converter modules are linked together in series and connected to the input of the transmission line to the load through a decoupling and line matching network. The dc-dc converter modules are phase activated such that for n modules, each module is activated equally 360 degree/n out of phase with respect to a successive module. The phased activation of the converter modules, combined with the square current waveforms out of the step up transformers, allows the power supply to operate with greatly reduced output capacitance values which minimizes the stored energy available for discharge into an electron beam gun or the like during arcing. The present power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle using simulated voltage feedback signals and voltage feedback loops. Circuitry is also provided for sensing incipient arc currents reflected at the output of the power supply and for simultaneously decoupling the power supply circuitry from the arcing load. 7 figs

  18. Design and Simulation of Microelectromechanical System Capacitive Shunt Switches

    Haslina Jaafar

    2009-01-01

    Full Text Available Problem statement: RF MEMS switch is one of MEMS area that creates devices that have great potential to improve the performance of communication circuits and systems and enables the realization of micro size mechanical switches embedded in electronics devices. The low voltage switches are necessary due to their compatibility of standard IC technology in RF application and microelectronics systems. In realizing MEMS switches with low actuation voltage, spring constant of beam must be reduced. Design and simulation of capacitive RF MEMS shunt switches with regards to the pull in voltage were presented. Approach: Design and simulation had been done by using commercial simulation package, CoventorWare 2006. Several switches were designed with different meander spring beams to obtain lower voltage actuations using Architect Module in CoventorWare 2006. Results: Results verified with Finite Element Method (FEM and simple mathematical modeling. Each design gave different voltage actuations. The lowest actuation voltage simulated was 1.9 V. Average difference of simulated and calculated values was about 16%. This is because no fringing field was included in calculation. Finite Element Method (FEM analysis was done for switch C. Results showed that lower voltage can be obtained by using serpentine spring which lowers the spring constant and pull-in voltage as well. The lower pull-in time was primarily due to its very small dimensions and mass Conclusion: Low-voltage capacitive shunt RF MEMS switches were designed and simulated. These switches had actuation voltages of 1.9-7.0 V depending on the serpentine design. The other performance particularly switch C had a pull-in time of 15 µ sec after a voltage of 0-20 V was applied and the resonant frequency is 3153.1 Hz.

  19. Characterisation of a highly symmetrical miniature capacitive triaxial accelerometer

    Lotters, J.C.; Olthuis, W.; Veltink, P.H.; Bergveld, P.

    1997-01-01

    A highly symmetrical cubic capacitive triaxial accelerometer for biomedical applications has been designed, realised and tested. The sensors are available in two outer dimensions, namely 2×2×2 and 5×5×5 mm3. The devices are mounted on a standard IC package for easy testing. Features of the sensor are a highly symmetrical cubic structure, capacitive coupling of the high frequency input voltage to the seismic mass and the use of the polymers polydimethylsiloxane (PDMS) as spring material betwee...

  20. Capacitive Touch User Interface and Implementation with Virtual Refrigerator

    MIT Academy of Engineering Global Technology and Engineering centre, Whirlpool of India

    2014-05-01

    Full Text Available The proposed User Interface incorporates 14 Touch keys, including slider and wheeler functionality using self capacitance technology, 24 side throw LED with intensity controlled Fade-IN, Fade-OUT effects, Buzzer chime, Voltage regulator circuit, and communication circuitry for the control board. The major advantage that this User Interface is that the entire assembly is less than 10mm thick including PCB, components, light guide and graphics sticker. In this project the mentioned capacitive touch user Interface is interfaced with a Lab view system simulating a virtual refrigerator capable of responding to the commands from the User Interface.

  1. An Annular Mechanical Temperature Compensation Structure for Gas-Sealed Capacitive Pressure Sensor

    Kohei Higuchi; Yonggang Jiang; Kazusuke Maenaka; Hidekuni Takao; Xiuchun Hao

    2012-01-01

    A novel gas-sealed capacitive pressure sensor with a temperature compensation structure is reported. The pressure sensor is sealed by Au-Au diffusion bonding under a nitrogen ambient with a pressure of 100 kPa and integrated with a platinum resistor-based temperature sensor for human activity monitoring applications. The capacitance-pressure and capacitance-temperature characteristics of the gas-sealed capacitive pressure sensor without temperature compensation structure are calculated. It is...

  2. Capacitance transient analysis of different-sized InAs/GaAs quantum dot structures.

    Song, Hooyoung; Kim, Jin Soak; Kim, Eun Kyu; Lee, Sang Jun; Noh, Sam Kyu

    2011-07-01

    The energy states of InAs/GaAs self-assembled quantum dots (QDs) were analyzed by comparing between two QD systems with different QD sizes. The electrical properties of the QD systems were investigated via capacitance-voltage measurements and capacitance transient spectroscopy (also known as deep-level transient spectroscopy) with selective carrier injection and extraction which can be achieved with very small pulse amplitude under bias variation. For the large QDs, several energy states were found with the use of selective carrier injection and extraction. The thermal-activation energies obtained from the capacitance transient spectra of the large QDs were distributed from 70 to 600 meV. This energy distribution was originated from the quantized states of the individual QDs and the size distribution of the QDs. The spectra of the small QDs showed a well-defined energy state of E(c) - 132 meV. From these results, it was estimated that two to four electrons fill a single QD under the proper measurement bias of 0.2 V pulse. PMID:22121745

  3. Voltage/Pitch Control for Maximization and Regulation of Active/Reactive Powers in Wind Turbines with Uncertainties

    Guo, Yi; Jiang, John N; Tang, Choon Yik; Ramakumar, Rama G

    2010-01-01

    This paper addresses the problem of controlling a variable-speed wind turbine with a Doubly Fed Induction Generator (DFIG), modeled as an electromechanically-coupled nonlinear system with rotor voltages and blade pitch angle as its inputs, active and reactive powers as its outputs, and most of the aerodynamic and mechanical parameters as its uncertainties. Using a blend of linear and nonlinear control strategies (including feedback linearization, pole placement, uncertainty estimation, and gradient-based potential function minimization) as well as time-scale separation in the dynamics, we develop a controller that is capable of maximizing the active power in the Maximum Power Tracking (MPT) mode, regulating the active power in the Power Regulation (PR) mode, seamlessly switching between the two modes, and simultaneously adjusting the reactive power to achieve a desired power factor. The controller consists of four cascaded components, uses realistic feedback signals, and operates without knowledge of the C_p-...

  4. Grid-Current-Feedback Active Damping for LCL Resonance in Grid-Connected Voltage-Source Converters

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2016-01-01

    adding a virtual impedance across the grid-side inductance. This added impedance is more precisely represented by a series RL branch in parallel with a negative inductance. The negative inductance helps to mitigate phase lag caused by time delays found in a digitally controlled system. The mitigation of......This paper investigates active damping of LCL-filter resonance in a grid-connected voltage-source converter with only grid-current feedback control. Basic analysis in the s-domain shows that the proposed damping technique with a negative high-pass filter along its damping path is equivalent to...... phase-lag, in turn, helps to shrink the region of nonminimum-phase behavior caused by negative virtual resistance inserted unintentionally by most digitally implemented active damping techniques. The presented high-pass-filtered active damping technique with a single grid-current feedback loop is thus a...

  5. Analysis and design of grid-current-feedback active damping for LCL resonance in grid-connected voltage source converters

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    2014-01-01

    This paper investigates the active damping of LCL-filter resonance within single-loop grid current control of grid-connected voltage source converters. First, the basic analysis in the continuous s-domain reveals that the grid-current-feedback active damping forms a virtual impedance across the...... grid-side inductor, and the use of a high-pass filter with a negative sign shapes the virtual impedance by an RL damper paralleled by a negative inductance. It is further found that such a negative virtual inductance plays a critical role in mitigating the phase lag caused by the time delay in a...... digital control system. The instability induced by the negative virtual resistance, which is commonly experienced in the feedback-type active damping, can thus be avoided. A systematic design method of the highpass filter is also proposed by the help of root locus analysis in the discrete z-domain. Lastly...

  6. Capacitance of circular patch resonator

    In this paper the capacitance of the circular microstrip patch resonator is computed. It is shown that the electrostatic problem can be formulated as a system of dual integral equations, and the most interesting techniques of solutions of these systems are reviewed. Some useful approximated formulas for the capacitance are derived and plots of the capacitance are finally given in a wide range of dielectric constants

  7. Capacitance of circular patch resonator

    Miano, G.; Verolino, L. [Dip. di Ingegneria Elettrica, Ist. Nazionale di Fisica Nucleare, Naples (Italy); Panariello, G. [Dip. di Ingegneria Elettronica, Naples (Italy); Vaccaro, V.G. [Ist. Nazionale di Fisica Nucleare, Naples (Italy). Dipt. di Scienze Fisiche

    1995-11-01

    In this paper the capacitance of the circular microstrip patch resonator is computed. It is shown that the electrostatic problem can be formulated as a system of dual integral equations, and the most interesting techniques of solutions of these systems are reviewed. Some useful approximated formulas for the capacitance are derived and plots of the capacitance are finally given in a wide range of dielectric constants.

  8. A QUALITATIVE ANALYSIS OF BIOMASS FLOW SENSING BEHAVIOR USING CAPACITIVE TECHNIQUE

    Rumana Tasnim

    2016-04-01

    Full Text Available Flowsensing technology from today’s application perspective has gained significant research interest over the past few years. Among the existing sensing techniques, electrostatic and capacitive sensing techniques have proven promising although cable capacitance and stray capacitance cause inaccuracy while measuring very small capacitances. The existing measurement circuit model is complicated and has flawed electrode arrangement. By sensing very small capacitive variation, the developed capacitive technique has proven capable of reducing the stray and residual capacitance effect by using an interface sensing circuit based on circular and semicircular shaped electrode and modified capacitive bridge. The proposed interface circuit is simulated via PSPICE for realizing the small capacitive variation with permittivity variation. Hardware implementation is carried out using a flow sensing set up that senses two kinds of biomass flow variation as a change of dielectric permittivity under room conditions. The output voltage has been reproduced as a representative of the flow. Moreover, a comprehensive investigation into experimental data shows an agreeable level of consistency with the simulation results.KEYWORDS:  electrodes; sensing; capacitance; electrostatic; piping; measurement

  9. Improved Capacitive Liquid Sensor

    Waldman, Francis A.

    1992-01-01

    Improved capacitive sensor used to detect presence and/or measure thickness of layer of liquid. Electrical impedance or admittance of sensor measured at prescribed frequency, and thickness of liquid inferred from predetermined theoretical or experimental relationship between impedance and thickness. Sensor is basically a three-terminal device. Features interdigitated driving and sensing electrodes and peripheral coplanar ground electrode that reduces parasitic effects. Patent-pending because first to utilize ground plane as "shunting" electrode. System less expensive than infrared, microwave, or refractive-index systems. Sensor successfully evaluated in commercial production plants to characterize emulsions, slurries, and solutions.

  10. A high voltage DC-DC converter driving a Dielectric Electro Active Polymer actuator for wind turbine flaps

    Thummala, Prasanth; Zhang, Zhe; Andersen, Michael A. E.; Thomsen, Ole Cornelius

    2012-01-01

    The Dielectric Electro Active Polymer (DEAP) material is a very thin (~80 μm) silicone elastomer film with a compliant metallic electrode layer on both sides. The DEAP is fundamentally a capacitor that is capable of very high strain. The property that the polymer changes its shape, as a result of...... topology to obtain high voltage at low current, for driving the DEAP actuator. Simulation and experimental results for uni-directional flyback converter topology are shown....... flaps. With the DEAP based high power actuator, it is expected to make a reliable and light solution with superior controllability. The current DEAP technology requires high DC voltage in the range of kV to fully utilize the DEAP material as an actuator. In this paper we propose a flyback converter......The Dielectric Electro Active Polymer (DEAP) material is a very thin (~80 μm) silicone elastomer film with a compliant metallic electrode layer on both sides. The DEAP is fundamentally a capacitor that is capable of very high strain. The property that the polymer changes its shape, as a result of...

  11. High-field actively detuneable transverse electromagnetic (TEM) coil with low-bias voltage for high-power RF transmission.

    Avdievich, Nikolai I; Bradshaw, Ken; Kuznetsov, Andrey M; Hetherington, Hoby P

    2007-06-01

    The design and construction of a 4T (170 MHz) transverse electromagnetic (TEM) actively detuneable quadrature head coil is described. Conventional schemes for active detuning require high negative bias voltages (>300 V) to prevent leakage of RF pulses with amplitudes of 1-2 kW. To extend the power handling capacity and avoid the use of high DC bias voltages, we developed an alternate method of detuning the volume coil. In this method the PIN diodes in the detuning circuits are shorted when the RF volume coil is tuned, and negatively biased with -12 V when the coil is detuned. To preserve the high Q(U)/Q(L) ratio of the TEM coil, we modified the method of Nabetani and Watkins (Proceedings of the 13th Annual Meeting of ISMRM, Kyoto, Japan, 2004, abstract 1574) by utilizing a high-impedance (approximately 200 Omega), lumped-element, quarter-wavelength transformer. A Q(U) of 500 was achieved for the detuneable TEM, such that incorporation of the detuning network had minimal effect (<1 dB) on the performance of the coil in vivo. PMID:17534919

  12. Novel Approach for Correlating Capacitance Data with Performance During Thin-Film Device Stress Studies: Preprint

    Graham, R. L.; Albin, D. S.; Clark, L. A.

    2011-08-01

    A new data mining algorithm was developed to identify the strongest correlations between capacitance data (measured between -1.5 V and +0.49 V) and 1st and 2nd level performance metrics (efficiency, open-circuit voltage (VOC), short-circuit current density (JSC), and fill-factor (FF)) during the stress testing of voltage-stabilized CdS/CdTe devices. When considering only correlations between 1st and 2nd level metrics, 96.5% of the observed variation in efficiency was attributed to FF. The overall decrease in VOC after 1000 hours of open-circuit, light-soak stress at 60 degrees C was about 1.5%. As determined by our algorithm, the most consistent correlation existing between FF and 3rd level metric capacitance data at all stages during stress testing was between FF and the apparent CdTe acceptor density (Na) calculated at a voltage of +0.49 V during forward voltage scans. Since the contribution of back contact capacitance to total capacitance increases with increasing positive voltage, this result suggests that FF degradation is associated with decreases in Na near the CdTe/back contact interface. Also of interest, it appears that capacitance data at these higher voltages appears to more accurately fit the one-sided abrupt junction model.

  13. Mechano-capacitive properties of polarized membranes.

    Mosgaard, Lars D; Zecchi, Karis A; Heimburg, Thomas

    2015-10-28

    Biological membranes are capacitors that can be charged by applying a field across the membrane. The charges on the capacitor exert a force on the membrane that leads to electrostriction, i.e. a thinning of the membrane. Since the force is quadratic in voltage, negative and positive voltage have an identical influence on the physics of symmetric membranes. However, this is not the case for a membrane with an asymmetry leading to a permanent electric polarization. Positive and negative voltages of identical magnitude lead to different properties. Such an asymmetry can originate from a lipid composition that is different on the two monolayers of the membrane, or from membrane curvature. The latter effect is called 'flexoelectricity'. As a consequence of permanent polarization, the membrane capacitor is discharged at a voltage different from zero. This leads to interesting electrical phenomena such as outward or inward rectification of membrane permeability. Here, we introduce a generalized theoretical framework, that treats capacitance, polarization, flexoelectricity, piezoelectricity and thermoelectricity in the same language. We show applications to electrostriction, membrane permeability and piezoelectricity and thermoelectricity close to melting transitions, where such effects are especially pronounced. PMID:26324950

  14. Capacitance Probe Resonator for Multichannel Electrometer

    Blaes, Brent R.; Schaefer, Rembrandt T> Glaser, Robert J.

    2012-01-01

    A multichannel electrometer voltmeter has been developed that employs a mechanical resonator with voltage-sensing capacitance-probe electrodes that enable high-impedance, high-voltage, radiation-hardened measurement of an Internal Electrostatic Discharge Monitor (IESDM) sensor. The IESDM is new sensor technology targeted for integration into a Space Environmental Monitor (SEM) subsystem used for the characterization and monitoring of deep dielectric charging on spacecraft. The resonator solution relies on a non-contact, voltage-sensing, sinusoidal-varying capacitor to achieve input impedances as high as 10 petaohms as determined by the resonator materials, geometries, cleanliness, and construction. The resonator is designed with one dominant mechanical degree of freedom, so it resonates as a simple harmonic oscillator and because of the linearity of the variable sense capacitor to displacement, generates a pure sinusoidal current signal for a fixed input voltage under measurement. This enables the use of an idealized phase-lock sensing scheme for optimal signal detection in the presence of noise.

  15. An active trap filter for high-power voltage source converters

    Bai, Haofeng; Wang, Xiongfei; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    This paper proposes a power electronic based device to actively trap the switching current ripples for highpower converters. Control principle and system design of the active trap filter are discussed first. Comparisons of the active trap filter with LCL and LLCL filters are then carried out in...

  16. Influence of Interface Traps and Electron-Hole Puddles on Quantum Capacitance and Conductivity in Graphene Field-Effect Transistors

    Zebrev, G. I.; Melnik, E. V.; Tselykovskiy, A. A.

    2010-01-01

    We study theoretically an influence of the near-interfacial insulator traps and electron-hole puddles on the small-signal capacitance and conductance characteristics of the gated graphene structures. Based on the self-consistent electrostatic consideration and taking into account the interface trap capacitance the explicit analytic expressions for charge carrier density and the quantum capacitance as functions of the gate voltage were obtained. This allows to extract the interface trap capaci...

  17. Capacitance of Gated GaAs/AlGaAs Heterostructures Subject to In-plane Magnetic Fields

    Jungwirth, T.; Smrcka, L.

    1995-01-01

    A detailed analysis of the capacitance of gated GaAs/AlGaAs heterostructures is presented. The nonlinear dependence of the capacitance on the gate voltage and in-plane magnetic field is discussed together with the capacitance quantum steps connected with a population of higher 2D gas subbands. The results of full self-consistent numerical calculations are compared to recent experimental data.

  18. A Highly Active Low Voltage Redox Mediator for Enhanced Rechargeability of Lithium-Oxygen Batteries.

    Kundu, Dipan; Black, Robert; Adams, Brian; Nazar, Linda F

    2015-12-23

    Owing to its high theoretical specific energy, the Li-oxygen battery is one of the fundamentally most promising energy storage systems, but also one of the most challenging. Poor rechargeability, involving the oxidation of insoluble and insulating lithium peroxide (Li2O2), has remained the "Achilles' heel" of this electrochemical energy storage system. We report here on a new redox mediator tris[4-(diethylamino)phenyl]amine (TDPA), that-at 3.1 V-exhibits the lowest and closest potential redox couple compared to the equilibrium voltage of the Li-oxygen cell of those reported to date, with a second couple also at a low potential of 3.5 V. We show it is a soluble "catalyst" capable of lowering the Li2O2 charging potential by >0.8 V without requiring direct electrical contact of the peroxide and that it also facilitates high discharge capacities. Its chemical and electrochemical stability, fast diffusion kinetics, and two dynamic redox potentials represent a significant advance in oxygen-evolution catalysis. It enables Li-O2 cells that can be recharged more than 100 cycles with average round-trip efficiencies >80%, opening a new avenue for practical Li-oxygen batteries. PMID:27163015

  19. Airway Hydration, Apical K(+) Secretion, and the Large-Conductance, Ca(2+)-activated and Voltage-dependent Potassium (BK) Channel.

    Kis, Adrian; Krick, Stefanie; Baumlin, Nathalie; Salathe, Matthias

    2016-04-01

    Large-conductance, calcium-activated, and voltage-gated K(+) (BK) channels are expressed in many tissues of the human body, where they play important roles in signaling not only in excitable but also in nonexcitable cells. Because BK channel properties are rendered in part by their association with four β and four γ subunits, their channel function can differ drastically, depending on in which cellular system they are expressed. Recent studies verify the importance of apically expressed BK channels for airway surface liquid homeostasis and therefore of their significant role in mucociliary clearance. Here, we review evidence that inflammatory cytokines, which contribute to airway diseases, can lead to reduced BK activity via a functional down-regulation of the γ regulatory subunit LRRC26. Therefore, manipulation of LRRC26 and pharmacological opening of BK channels represent two novel concepts of targeting epithelial dysfunction in inflammatory airway diseases. PMID:27115952

  20. Asymmetric synthesis of crambescin A-C carboxylic acids and their inhibitory activity on voltage-gated sodium channels.

    Nakazaki, Atsuo; Nakane, Yoshiki; Ishikawa, Yuki; Yotsu-Yamashita, Mari; Nishikawa, Toshio

    2016-06-21

    Synthesis of both enantiomers of crambescin B carboxylic acid is described. A cis-enyne starting material was epoxidized under the conditions of Katsuki asymmetric epoxidation to give 95% ee of the epoxide, which was transformed to crambescin B carboxylic acid via bromocation-triggered cascade cyclization as the key step. Enantiomerically pure crambescin A and C carboxylic acids were also synthesized from the product of the cascade reaction. Structure-activity relationship (SAR) studies against voltage-gated sodium channel (VGSC) inhibition using those synthetic compounds revealed that the natural enantiomer of crambescin B carboxylic acid was most active and comparable to tetrodotoxin, and the unalkylated cyclic guanidinium structure is indispensible, while the carboxylate moiety is not important. The absolute stereochemistry of crambescin A was determined by a comparison of the methyl ester derived from natural crambescin A with that derived from the stereochemically defined crambescin A carboxylic acid synthesized in this study. PMID:27215973

  1. Low voltage RF MEMS variable capacitor with linear C-V response

    Elshurafa, Amro M.

    2012-07-23

    An RF MEMS variable capacitor, fabricated in the PolyMUMPS process and tuned electrostatically, possessing a linear capacitance-voltage response is reported. The measured quality factor of the device was 17 at 1GHz, while the tuning range was 1.2:1 and was achieved at an actuation DC voltage of 8V only. Further, the linear regression coefficient was 0.98. The variable capacitor was created such that it has both vertical and horizontal capacitances present. As the top suspended plate moves towards the bottom fixed plate, the vertical capacitance increases whereas the horizontal capacitance decreases simultaneously such that the sum of the two capacitances yields a linear capacitance-voltage relation. © 2012 The Institution of Engineering and Technology.

  2. A novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances

    Dong Linxi; Chen Jindan; Yan Haixia; Huo Weihong; Li Yongjie; Sun Lingling

    2009-01-01

    The comb capacitances fabricated by deep reactive ion etching (RIE) process have high aspect ratio which is usually smaller than 30 : 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate's effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio (30 : 1) of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy (FEM) tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.

  3. Compensation of the detector capacitance presented to charge-sensitive preamplifiers using the Miller effect

    Kwon, Inyong, E-mail: iykwon@umich.edu [University of Michigan, Ann Arbor, MI (United States); Kang, Taehoon, E-mail: thnkang@umich.edu [University of Michigan, Ann Arbor, MI (United States); Wells, Byron T., E-mail: wells@galtresearch.com [Galt LLC, Ypsilanti, MI (United States); D’Aries, Lawrence J., E-mail: lawrence.j.daries.civ@mail.mil [Picatinny Arsenal, Rockaway Township, NJ (United States); Hammig, Mark D., E-mail: hammig@umich.edu [University of Michigan, Ann Arbor, MI (United States)

    2015-06-01

    This paper describes an integrated circuit design for a modified charge-sensitive amplifier (CSA) that compensates for the effect of capacitance presented by nuclear radiation detectors and other sensors. For applications that require large area semiconductor detectors or for those semiconductor sensors derived from high permittivity materials such as PbSe, the detector capacitance can degrade the system gain and bandwidth of a front-end preamplifier, resulting in extended rise times and attenuated output voltage signals during pulse formation. In order to suppress the effect of sensor capacitance, we applied a bootstrap technique into a traditional CSA. The technique exploits the Miller effect by reducing the effective voltage difference between the two sides of a radiation detector which minimizes the capacitance presented to the differential common-source amplifier. This new configuration is successfully designed to produce effective gain even at high detector capacitance. The entire circuit, including a core CSA with feedback components and a bootstrap amplifier, are implemented in a 0.18 μm CMOS process with a 3.3 V supply voltage. - Highlights: • A modified CSA was implemented for detector capacitance compensation. • Increasing detector capacitance degrades gain and rise time. • A bootstrap amplifier exploiting the Miller effect is described. • It allows using large area radiation sensors for high radiation-interaction rates. • Intensive noise analyses show that SNR is much better with the technique.

  4. Compensation of the detector capacitance presented to charge-sensitive preamplifiers using the Miller effect

    This paper describes an integrated circuit design for a modified charge-sensitive amplifier (CSA) that compensates for the effect of capacitance presented by nuclear radiation detectors and other sensors. For applications that require large area semiconductor detectors or for those semiconductor sensors derived from high permittivity materials such as PbSe, the detector capacitance can degrade the system gain and bandwidth of a front-end preamplifier, resulting in extended rise times and attenuated output voltage signals during pulse formation. In order to suppress the effect of sensor capacitance, we applied a bootstrap technique into a traditional CSA. The technique exploits the Miller effect by reducing the effective voltage difference between the two sides of a radiation detector which minimizes the capacitance presented to the differential common-source amplifier. This new configuration is successfully designed to produce effective gain even at high detector capacitance. The entire circuit, including a core CSA with feedback components and a bootstrap amplifier, are implemented in a 0.18 μm CMOS process with a 3.3 V supply voltage. - Highlights: • A modified CSA was implemented for detector capacitance compensation. • Increasing detector capacitance degrades gain and rise time. • A bootstrap amplifier exploiting the Miller effect is described. • It allows using large area radiation sensors for high radiation-interaction rates. • Intensive noise analyses show that SNR is much better with the technique

  5. Cell swelling activates ATP-dependent voltage-gated chloride channels in M-1 mouse cortical collecting duct cells.

    Meyer, K; Korbmacher, C

    1996-09-01

    In the present study we used whole-cell patch clamp recordings to investigate swelling-activated Cl-currents (ICl-swell) in M-1 mouse cortical collecting duct (CCD) cells. Hypotonic cell swelling reversibly increased the whole-cell Cl- conductance by about 30-fold. The I-V relationship was outwardly-rectifying and ICl-swell displayed a characteristic voltage-dependence with relatively fast inactivation upon large depolarizing and slow activation upon hyperpolarizing voltage steps. Reversal potential measurements revealed a selectivity sequence SCN- > I- > Br- > Cl- > > gluconate. ICl-swell was inhibited by tamoxifen, NPPB (5-nitro-2(3-phenylpropylamino)-benzoate), DIDS (4,4'-diisothiocyanostilbene-2,2'-disulphonic acid), flufenamic acid, niflumic acid, and glibenclamide, in descending order of potency. Extracellular cAMP had no significant effect. ICl-swell was Ca2+ independent, but current activation depended on the presence of a high-energy gamma-phosphate group from intracellular ATP or ATP gamma S. Moreover, it depended on the presence of intracellular Mg2+ and was inhibited by staurosporine, which indicates that a phosphorylation step is involved in channel activation. Increasing the cytosolic Ca2+ concentration by using ionomycin stimulated Cl- currents with a voltage dependence different from that of ICl-swell. Analysis of whole-cell current records during early onset of ICl-swell and during final recovery revealed discontinuous step-like changes of the whole-cell current level which were not observed under nonswelling conditions. A single-channel I-V curve constructed using the smallest resolvable current transitions detected at various holding potentials and revealed a slope conductance of 55, 15, and 8 pS at +120, 0, and -120 mV, respectively. The larger current steps observed in these recordings had about 2, 3, or 4 times the size of the putative single-channel current amplitude, suggesting a coordinated gating of several individual channels or channel

  6. Ubiquitin-activating enzyme (UBA1) is required for sperm capacitation, acrosomal exocytosis and sperm-egg coat penetration during porcine fertilization

    Yi, Y.-J.; Zimmermann, S.W.; Manandhar, G.; Odhiambo, J.F.; Kennedy, C.; Jonáková, Věra; Maňásková-Postlerová, Pavla; Sutovsky, M.; Park, C.-S.; Sutovsky, P.

    2012-01-01

    Roč. 35, č. 2 (2012), s. 196-210. ISSN 0105-6263 R&D Projects: GA ČR(CZ) GA303/09/1285; GA MŠk(CZ) 1M06011; GA MZd(CZ) NS10009 Institutional research plan: CEZ:AV0Z50520701 Keywords : acrosome * capacitation * fertilization * ubiqutin Subject RIV: CE - Biochemistry Impact factor: 3.565, year: 2012

  7. Capacitive Micromachined Ultrasonic Transducers (CMUTs for Underwater Imaging Applications

    Jinlong Song

    2015-09-01

    Full Text Available A capacitive micromachined ultrasonic transducer structure for use in underwater imaging is designed, fabricated and tested in this paper. In this structure, a silicon dioxide insulation layer is inserted between the top electrodes and the vibration membrane to prevent ohmic contact. The capacitance-voltage (C-V characteristic curve shows that the transducer offers suitable levels of hysteresis and repeatability performance. The −6 dB center frequency is 540 kHz and the transducer has a bandwidth of 840 kHz for a relative bandwidth of 155%. Underwater pressure of 143.43 Pa is achieved 1 m away from the capacitive micromachined ultrasonic transducer under 20  excitation. Two-dimensional underwater ultrasonic imaging, which is able to prove that a rectangular object is present underwater, is achieved. The results presented here indicate that our work will be highly beneficial for the establishment of an underwater ultrasonic imaging system.

  8. Effect of surfactants on capacitance properties of carbon electrodes

    Effect of surfactants present in alkaline solutions on the capacitance of carbon electrodes has been studied. Different types of surfactants, i.e., sodium and lithium dodecyl sulphate as anionic surfactants, tetrapropylammonium bromide and iodide as cationic surfactants and polymer of polyethylene glycol and p-t-octylophenol (commercially called Triton® X-100) as non-ionic one have been selected for this target. Concentration of these electrolyte additives was 0.005 mol L−1. Decreasing the surface tension in the electrode/electrolyte interface allows better penetration of electrolyte into the pores. However, surfactants played a different role depending on the electrode polarity. Detailed analysis of capacitance versus current load, frequency dependence as well as self-discharge, cyclability and behaviour in wider voltage range proved especially a profitable effect of Triton® X-100 on capacitor operating in alkaline solution. Influence of surfactant concentration on capacitance properties was also investigated.

  9. A Wearable Capacitive Sensor for Monitoring Human Respiratory Rate

    Kundu, Subrata Kumar; Kumagai, Shinya; Sasaki, Minoru

    2013-04-01

    Realizing an untethered, low-cost, and comfortably wearable respiratory rate sensor for long-term breathing monitoring application still remains a challenge. In this paper, a conductive-textile-based wearable respiratory rate sensing technique based on the capacitive sensing approach is proposed. The sensing unit consists of two conductive textile electrodes that can be easily fabricated, laminated, and integrated in garments. Respiration cycle is detected by measuring the capacitance of two electrodes placed on the inner anterior and posterior sides of a T-shirt at either the abdomen or chest position. A convenient wearable respiratory sensor setup with a capacitance-to-voltage converter has been devised. Respiratory rate as well as breathing mode can be accurately identified using the designed sensor. The sensor output provides significant information on respiratory flow. The effectiveness of the proposed system for different breathing patterns has been evaluated by experiments.

  10. Fabrication of capacitively-shunted superconducting qubits

    Yoder, Jonilyn L.; Gudmundsen, Theodore J.; Bolkhovsky, Vladimir; Welander, Paul B.; Gustavsson, Simon; Hover, David; Kerman, Andrew J.; Sears, Adam P.; Oliver, William D.

    2014-03-01

    Improvements in superconducting qubit coherence times and reproducibility have been demonstrated using capacitive shunting. In this study, we present methods for the preparation of both capacitively-shunted charge qubits (transmons) and capacitively-shunted flux qubits. Hybrid fabrication techniques were employed to combine high-quality-factor aluminum capacitive shunts with shadow-evaporated Josephson junctions, and the Josephson junctions were prepared using suspended-bridge germanium masks. We also will describe process testing results that were acquired to assess wafer-to-wafer reproducibility of our fabrication protocols. This research was funded in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA); and by the Assistant Secretary of Defense for Research and Engineering under Air Force Contract number FA8721-05-C-0002. All statements of fact, opinion or conclusions contained herein are those of the authors and should not be construed as representing the official views or policies of IARPA, the ODNI, or the U.S. Government.

  11. Real-Time Control of Shunt Active Power Filter under Distorted Grid Voltage and Unbalanced Load Condition Using Self Tuning Filter

    Biricik, Samet; Redif, Soydan; Ozerdem, Ozgur; Khadem, Shafiuzzaman K.; Basu, Malabika

    2014-01-01

    In this paper, an alternative control method is proposed to improve the harmonic suppression efficiency of the active power filter in a distorted and an unbalanced power system to compensate for the perturbations caused by the unbalanced non-linear loads. The proposed method uses a self-tuning filter (STF) to process the grid voltage in order to provide a uniform reference voltage to obtain the correct angular position of the phase locked loop. Moreover, the required compensation currents are...

  12. Optimal pricing of capacitated networks

    Grigoriev, Alexander; Loon, van Joyce; Sitters, René; Uetz, Marc

    2009-01-01

    We address the algorithmic complexity of a profit maximization problem in capacitated, undirected networks. We are asked to price a set of $m$ capacitated network links to serve a set of $n$ potential customers. Each customer is interested in purchasing a network connection that is specified by a si

  13. Capacitively coupled hybrid pixel assemblies for the CLIC vertex detector

    Tehrani, N. Alipour; Arfaoui, S.; Benoit, M.; Dannheim, D.; Dette, K.; Hynds, D.; Kulis, S.; Perić, I.; Petrič, M.; Redford, S.; Sicking, E.; Valerio, P.

    2016-07-01

    The vertex detector at the proposed CLIC multi-TeV linear e+e- collider must have minimal material content and high spatial resolution, combined with accurate time-stamping to cope with the expected high rate of beam-induced backgrounds. One of the options being considered is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel ASICs. A prototype of such an assembly, using two custom designed chips (CCPDv3 as active sensor glued to a CLICpix readout chip), has been characterised both in the lab and in beam tests at the CERN SPS using 120 GeV/c positively charged hadrons. Results of these characterisation studies are presented both for single and dual amplification stages in the active sensor, where efficiencies of greater than 99% have been achieved at -60 V substrate bias, with a single hit resolution of 6.1 μm . Pixel cross-coupling results are also presented, showing the sensitivity to placement precision and planarity of the glue layer.

  14. Integrated Reconfigurable High-Voltage Transmitting Circuit for CMUTs

    Llimos Muntal, Pere; Larsen, Dennis Øland; Jørgensen, Ivan Harald Holger; Bruun, Erik

    2014-01-01

    In this paper a full high-voltage transmitting cir- cuit aimed for capacitive micromachined ultrasonic transducers (CMUTs) used in ultrasound medical applications is designed and implemented in a 0.35 μm high-voltage CMOS process. The CMUT is single-ended driven. The design is taped-out and...

  15. DC-Link Capacitor Voltage Regulation for Three-Phase Three-Level Inverter-Based Shunt Active Power Filter with Inverted Error Deviation Control

    Yap Hoon

    2016-07-01

    Full Text Available A new control technique known as inverted error deviation (IED control is incorporated into the main DC-link capacitor voltage regulation algorithm of a three-level neutral-point diode clamped (NPC inverter-based shunt active power filter (SAPF to enhance its performance in overall DC-link voltage regulation so as to improve its harmonics mitigation performances. In the SAPF controller, DC-link capacitor voltage regulation algorithms with either the proportional-integral (PI or fuzzy logic control (FLC technique have played a significant role in maintaining a constant DC-link voltage across the DC-link capacitors. However, both techniques are mostly operated based on a direct voltage error manipulation approach which is insufficient to address the severe DC-link voltage deviation that occurs during dynamic-state conditions. As a result, the conventional algorithms perform poorly with large overshoot, undershoot, and slow response time. Therefore, the IED control technique is proposed to precisely address the DC-link voltage deviation. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and experimental implementation utilizing a TMS320F28335 Digital Signal Processor (DSP are performed. Moreover, conventional algorithms with PI and FLC techniques are tested too for comparison purposes. Both simulation and experimental results are presented, confirming the improvement achieved by the proposed algorithm in terms of accuracy and dynamic response in comparison to the conventional algorithms.

  16. Distributed Capacitive Sensor for Sample Mass Measurement

    Toda, Risaku; McKinney, Colin; Jackson, Shannon P.; Mojarradi, Mohammad; Manohara, Harish; Trebi-Ollennu, Ashitey

    2011-01-01

    Previous robotic sample return missions lacked in situ sample verification/ quantity measurement instruments. Therefore, the outcome of the mission remained unclear until spacecraft return. In situ sample verification systems such as this Distributed Capacitive (DisC) sensor would enable an unmanned spacecraft system to re-attempt the sample acquisition procedures until the capture of desired sample quantity is positively confirmed, thereby maximizing the prospect for scientific reward. The DisC device contains a 10-cm-diameter pressure-sensitive elastic membrane placed at the bottom of a sample canister. The membrane deforms under the weight of accumulating planetary sample. The membrane is positioned in close proximity to an opposing rigid substrate with a narrow gap. The deformation of the membrane makes the gap narrower, resulting in increased capacitance between the two parallel plates (elastic membrane and rigid substrate). C-V conversion circuits on a nearby PCB (printed circuit board) provide capacitance readout via LVDS (low-voltage differential signaling) interface. The capacitance method was chosen over other potential approaches such as the piezoelectric method because of its inherent temperature stability advantage. A reference capacitor and temperature sensor are embedded in the system to compensate for temperature effects. The pressure-sensitive membranes are aluminum 6061, stainless steel (SUS) 403, and metal-coated polyimide plates. The thicknesses of these membranes range from 250 to 500 m. The rigid substrate is made with a 1- to 2-mm-thick wafer of one of the following materials depending on the application requirements glass, silicon, polyimide, PCB substrate. The glass substrate is fabricated by a microelectromechanical systems (MEMS) fabrication approach. Several concentric electrode patterns are printed on the substrate. The initial gap between the two plates, 100 m, is defined by a silicon spacer ring that is anodically bonded to the glass

  17. An integrated energy-efficient capacitive sensor digital interface circuit

    Omran, Hesham

    2014-06-19

    In this paper, we propose an energy-efficient 13-bit capacitive sensor interface circuit. The proposed design fully relies on successive approximation algorithm, which eliminates the need for oversampling and digital decimation filtering, and thus low-power consumption is achieved. The proposed architecture employs a charge amplifier stage to acheive parasitic insensitive operation and fine absolute resolution. Moreover, the output code is not affected by offset voltages or charge injection. The successive approximation algorithm is implemented in the capacitance-domain using a coarse-fine programmable capacitor array, which allows digitizing wide capacitance range in compact area. Analysis for the maximum achievable resolution due to mismatch is provided. The proposed design is insensitive to any reference voltage or current which translates to low temperature sensitivity. The operation of a prototype fabricated in a standard CMOS technology is experimentally verified using both on-chip and off-chip capacitive sensors. Compared to similar prior work, the fabricated prototype achieves and excellent energy efficiency of 34 pJ/step.

  18. Influence of a voltage compensation type active superconducting fault current limiter on the transient stability of power system

    Chen, L.; Tang, Y. J.; Shi, J.; Chen, N.; Song, M.; Cheng, S. J.; Hu, Y.; Chen, X. S.

    2009-10-01

    We have proposed a voltage compensation type active superconducting fault current limiter (SFCL). In this paper, the influence of the SFCL on the transient stability of power system is investigated. For the typical one-machine infinite-bus system, the power-angle characteristics of generator with SFCL are studied in different working conditions, and the transient physical process is analyzed. Using MATLAB SIMULINK, the power-angle swing curves are simulated under different current-limiting modes, fault types and fault clearance times. The results show that the proposed SFCL can effectively reduce the transient swing amplitude of rotor and extend the critical clearance time under mode 1, compared with mode 2 and mode 3 having few effects on enhancing the transient stability.

  19. Influence of a voltage compensation type active superconducting fault current limiter on the transient stability of power system

    Chen, L., E-mail: stclchen1982@yahoo.com.c [R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China); Tang, Y.J.; Shi, J.; Chen, N.; Song, M.; Cheng, S.J. [R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China); Hu, Y.; Chen, X.S. [State Grid Electric Power Research Institute, Wuhan 430074 (China)

    2009-10-15

    We have proposed a voltage compensation type active superconducting fault current limiter (SFCL). In this paper, the influence of the SFCL on the transient stability of power system is investigated. For the typical one-machine infinite-bus system, the power-angle characteristics of generator with SFCL are studied in different working conditions, and the transient physical process is analyzed. Using MATLAB SIMULINK, the power-angle swing curves are simulated under different current-limiting modes, fault types and fault clearance times. The results show that the proposed SFCL can effectively reduce the transient swing amplitude of rotor and extend the critical clearance time under mode 1, compared with mode 2 and mode 3 having few effects on enhancing the transient stability.

  20. Influence of a voltage compensation type active superconducting fault current limiter on the transient stability of power system

    We have proposed a voltage compensation type active superconducting fault current limiter (SFCL). In this paper, the influence of the SFCL on the transient stability of power system is investigated. For the typical one-machine infinite-bus system, the power-angle characteristics of generator with SFCL are studied in different working conditions, and the transient physical process is analyzed. Using MATLAB SIMULINK, the power-angle swing curves are simulated under different current-limiting modes, fault types and fault clearance times. The results show that the proposed SFCL can effectively reduce the transient swing amplitude of rotor and extend the critical clearance time under mode 1, compared with mode 2 and mode 3 having few effects on enhancing the transient stability.

  1. Synthesis of a CNT-grafted TiO{sub 2} nanocatalyst and its activity triggered by a DC voltage

    Kuo, C-S [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China); Tseng, Y-H [Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, 310 (China); Lin, H-Y [Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716 (United States); Huang, C-H [Energy and Environment Research Laboratories, Industrial Technology Research Institute, Hsinchu, 310 (China); Shen, C-Y [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China); Li, Y-Y [Department of Chemical Engineering, National Chung Cheng University, Chia-Yi 621 (China); Shah, S Ismat [Department of Materials Sciences and Engineering, University of Delaware, Newark, DE 19716 (United States); Huang, C-P [Department of Civil and Environmental Engineering, University of Delaware, Newark, DE 19716 (United States)

    2007-11-21

    Carbon nanotube (CNT)-grafted TiO{sub 2} (CNT/TiO{sub 2}) was synthesized as an electrically conductive catalyst that exhibits redox ability under electrical excitation besides ultraviolet (UV) irradiation. The CNT/TiO{sub 2} material was synthesized by a two-step process. Ni nanoparticles were photodeposited onto TiO{sub 2} first. The Ni nanoparticles then served as seeds for the growth of CNTs using the chemical vapor deposition (CVD) of C{sub 2}H{sub 2}. The CNT/TiO{sub 2} nanocomposite exhibits strong oxidation activity toward NO gas molecules via both photocatalysis under UV irradiation and electrocatalysis under a DC voltage of 500 V in dark conditions.

  2. Design status and procurement activities of the High Voltage Deck 1 and Bushing for the ITER Neutral Beam Injector

    Highlights: ► ITER Neutral Beam Injector includes several non-standard components. ► The design status of the −1 MVdc HVD1 and Bushing is described. ► The paper reports also on the integrated layout of the two components. ► Preliminary electrostatic and thermal analyses are presented. ► Procurement activities are outlined. -- Abstract: The ITER Neutral Beam Injector (NBI) power supply system includes several non-standard components, whose ratings go beyond the present industrial practice. Two of these items, to be procured by Fusion for Energy, are: 1.A −1 MVdc air-insulated Faraday cage, called High Voltage Deck 1 (HVD1), hosting the Ion Source and Extractor Power Supplies (ISEPS) and the associated diagnostics. 2.A −1 MVdc feedthrough, called HVD1-TL Bushing, aimed at connecting the HVD1 to the gas (SF6) insulated Transmission Line (TL), containing inside its High Voltage (HV) conductor all ISEPS power and control cables coming from the HVD1 to be connected to the NBI Ion Source services. The paper deals with the status of the design of the HVD1 and HVD1-TL Bushing, focusing on insulation, mechanical and thermal issues as well as on their integration with the other components of the power supply system. In particular, the insulation issue of the integrated system has been addressed by means of an electrostatic Finite Element (FE) analysis whilst a FE thermal simulation has been carried out to assess the impact of the dissipation of the proposed design of the inner conductors (ISEPS conductors) not actively cooled. Finally, the paper describes the status of procurement strategy and execution

  3. Analysis of voltage modulation based active damping techniques for small DC-link drive system

    Wang, Dong; Lu, Kaiyuan; Rasmussen, Peter Omand; Máthé, Lászlo; Yang, Feng

    Small DC-link drive system, built with film capacitor in the DC link, may have the advantages of longer lifetime and the possibility to achieve a more compact design of capacitor bank at medium and high power rates. However, it exhibits instability problem, especially when it is fed by a soft grid...... without the requirements of the information of system parameters and operating conditions. Finally, active damping techniques with minimized current magnitude and total duty cycle are discussed, in order to fit various operating conditions. Simulation and experimental results are presented to verify the....... Therefore, active damping techniques are usually needed in order to stabilize the system. This paper firstly describes the essential idea of active damping methods from energy flow point of view. Then a new method named as “virtual positive impedance” method is introduced to ensure the dc-link stability...

  4. Hair cells use active zones with different voltage dependence of Ca2+ influx to decompose sounds into complementary neural codes.

    Ohn, Tzu-Lun; Rutherford, Mark A; Jing, Zhizi; Jung, Sangyong; Duque-Afonso, Carlos J; Hoch, Gerhard; Picher, Maria Magdalena; Scharinger, Anja; Strenzke, Nicola; Moser, Tobias

    2016-08-01

    For sounds of a given frequency, spiral ganglion neurons (SGNs) with different thresholds and dynamic ranges collectively encode the wide range of audible sound pressures. Heterogeneity of synapses between inner hair cells (IHCs) and SGNs is an attractive candidate mechanism for generating complementary neural codes covering the entire dynamic range. Here, we quantified active zone (AZ) properties as a function of AZ position within mouse IHCs by combining patch clamp and imaging of presynaptic Ca(2+) influx and by immunohistochemistry. We report substantial AZ heterogeneity whereby the voltage of half-maximal activation of Ca(2+) influx ranged over ∼20 mV. Ca(2+) influx at AZs facing away from the ganglion activated at weaker depolarizations. Estimates of AZ size and Ca(2+) channel number were correlated and larger when AZs faced the ganglion. Disruption of the deafness gene GIPC3 in mice shifted the activation of presynaptic Ca(2+) influx to more hyperpolarized potentials and increased the spontaneous SGN discharge. Moreover, Gipc3 disruption enhanced Ca(2+) influx and exocytosis in IHCs, reversed the spatial gradient of maximal Ca(2+) influx in IHCs, and increased the maximal firing rate of SGNs at sound onset. We propose that IHCs diversify Ca(2+) channel properties among AZs and thereby contribute to decomposing auditory information into complementary representations in SGNs. PMID:27462107

  5. Distortion-Free CV/CC AC Power Supply Having the Unity Input Power Factor by the Use of Variable Capacitance Devices

    Katsuki, Akihiko; Yoshimatsu, Koichiro; Tanoue, Hidetaka; Sugimoto, Yuichi

    2014-01-01

    A new CV (Constant-Voltage) CC (Constant-Current) ac power regulator is proposed. Our original Variable Capacitance Device of linear reactance device is utilized in the power stage. This device makes almost no distortion. In this circuit, a sinusoidal output voltage and a high efficiency can be obtained. For the purpose of output voltage/current control and input power-factor correction, two Variable Capacitance Devices were adopted. Two dc-dc converters were used for highspeed driver of thes...

  6. High-Performance Harmonic Isolation and Load Voltage Regulation of the Three-Phase Series Active Filter Utilizing the Waveform Reconstruction Method

    Senturk, Osman Selcuk; Hava, Ahmet M.

    2009-01-01

    This paper develops a waveform reconstruction method (WRM) for high accuracy and bandwidth signal decomposition of voltage-harmonic-type three-phase diode rectifier load voltage into its harmonic and fundamental components, which are utilized in the series active filter (SAF) control algorithms....... The SAF-compensated system utilizing WRM provides highperformance load harmonic voltage isolation and load voltage regulation at steady-state and during transients compared to the system utilizing the synchronous reference-frame-based signal decomposition. In addition, reducing the line current...... sampling delay in the discrete-time implementation enhances the stability of the SAF. The simulations and experimental studies of a 10-kW three-phase SAF-compensated system prove the theory....

  7. Capacitance-Based Frequency Adjustment of Micro Piezoelectric Vibration Generator

    Xinhua Mao

    2014-01-01

    Full Text Available Micro piezoelectric vibration generator has a wide application in the field of microelectronics. Its natural frequency is unchanged after being manufactured. However, resonance cannot occur when the natural frequencies of a piezoelectric generator and the source of vibration frequency are not consistent. Output voltage of the piezoelectric generator will sharply decline. It cannot normally supply power for electronic devices. In order to make the natural frequency of the generator approach the frequency of vibration source, the capacitance FM technology is adopted in this paper. Different capacitance FM schemes are designed by different locations of the adjustment layer. The corresponding capacitance FM models have been established. Characteristic and effect of the capacitance FM have been simulated by the FM model. Experimental results show that the natural frequency of the generator could vary from 46.5 Hz to 42.4 Hz when the bypass capacitance value increases from 0 nF to 30 nF. The natural frequency of a piezoelectric vibration generator could be continuously adjusted by this method.

  8. Low-Temperature Scanning Capacitance Probe for Imaging Electron Motion

    Novel techniques to probe electronic properties at the nanoscale can shed light on the physics of nanoscale devices. In particular, studying the scattering of electrons from edges and apertures at the nanoscale and imaging the electron profile in a quantum dot, have been of interest [1]. In this paper, we present the design and implementation of a cooled scanning capacitance probe that operates at liquid He temperatures to image electron waves in nanodevices. The conducting tip of a scanned probe microscope is held above the nanoscale structure, and an applied sample-to-tip voltage creates an image charge that is measured by a cooled charge amplifier [2] adjacent to the tip. The circuit is based on a low-capacitance, high- electron-mobility transistor (Fujitsu FHX35X). The input is a capacitance bridge formed by a low capacitance pinched-off HEMT transistor and tip-sample capacitance. We have achieved low noise level (0.13 e/VHz) and high spatial resolution (100 nm) for this technique, which promises to be a useful tool to study electronic behavior in nanoscale devices

  9. Logarithmic derivative method and system for capacitance measurement

    Wu, Yichun; Wang, Lingzhi; Cai, Yuanfeng; Wu, Cunqiao

    2015-08-01

    A novel method based on logarithmic derivative is introduced to analyze multi-lifetime decay. As the discharge voltage signal of a RC circuit is a special kind of multi-lifetime exponential decay, the logarithmic derivative method can be used to measure single capacitance and multiple capacitances. With the logarithmic derivative method, a log(t) curve strongly peaked at precisely log(τ) is obtained, where the lifetime τ equals to RC. In a measurement system, if the resistance R is known, then the capacitance under test can be calculated. A logarithmic derivative curve fitting method is also presented, which has better anti-noise capability than the method that simply finds the maximum data on the peak. The curve fitting method can also be used for multiple capacitors measurement. To measure small capacitances, a large enough time window of the measuring instrument is required. Based on a field programmable gate array and a high speed analog-to-digital converter, a measurement system is developed. This system can provide the 16-bit resolution with sampling rate up to 250 MHz, which has a large enough time window for measuring lifetime shorter than 10-8 s. To reduce the amount of data needed to be stored and the noise due to the derivative treatment of transient data, the interpolation and noise-filter algorithms are employed. Experiments indicate that the logarithmic derivative method and system are suitable for the measurement of capacitances discharge and other exponential decay processes.

  10. In Vivo Mesoscopic Voltage-Sensitive Dye Imaging of Brain Activation

    Tang, Qinggong; Tsytsarev, Vassiliy; Frank, Aaron; Wu, Yalun; Chen, Chao-Wei; Erzurumlu, Reha S.; Chen, Yu

    2016-04-01

    Functional mapping of brain activity is important in elucidating how neural networks operate in the living brain. The whisker sensory system of rodents is an excellent model to study peripherally evoked neural activity in the central nervous system. Each facial whisker is represented by discrete modules of neurons all along the pathway leading to the neocortex. These modules are called “barrels” in layer 4 of the primary somatosensory cortex. Their location (approximately 300–500 μm below cortical surface) allows for convenient imaging of whisker-evoked neural activity in vivo. Fluorescence laminar optical tomography (FLOT) provides depth-resolved fluorescence molecular information with an imaging depth of a few millimeters. Angled illumination and detection configurations can improve both resolution and penetration depth. We applied angled FLOT (aFLOT) to record 3D neural activities evoked in the whisker system of mice by deflection of a single whisker in vivo. A 100 μm capillary and a pair of microelectrodes were inserted to the mouse brain to test the capability of the imaging system. The results show that it is possible to obtain 3D functional maps of the sensory periphery in the brain. This approach can be broadly applicable to functional imaging of other brain structures.

  11. Minimization of the transformer inter-winding parasitic capacitance for modular stacking power supply applications

    Nguyen-Duy, Khiem; Ouyang, Ziwei; Knott, Arnold; Andersen, Michael A. E.

    2014-01-01

    In an isolated power supply, the inter-winding parasitic capacitance plays a vital role in the mitigation of common mode noise currents created by fast voltage transient responses. The lower the transformer inter-winding capacitance, the more immune the power supply is to fast voltage transient...... responses. This requirement is even more critical for modular stacking applications in which multiple power supplies are stacked. This paper addresses the issue by presenting a detailed analysis and design of an unconventional isolated power supply that uses a ring core transformer with a very low inter......-winding parasitic capacitance of 10 pF. Considering its output power of 300 W, this approach yields about 0.033 pF/W inter-winding capacitance over output power, approximately thirty times lower than existing approaches in the literature. This makes the converter a suitable solution for modular stacking of fast...

  12. Encapsulation of Capacitive Micromachined Ultrasonic Transducers Using Viscoelastic Polymer

    Lin, Der-Song; Zhuang, Xuefeng; Wong, Serena H.; Kupnik, Mario; Khuri-Yakub, Butrus Thomas

    2010-01-01

    The packaging of a medical imaging or therapeutic ultrasound transducer should provide protective insulation while maintaining high performance. For a capacitive micromachined ultrasonic transducer (CMUT), an ideal encapsulation coating would therefore require a limited and predictable change on the static operation point and the dynamic performance, while insulating the high dc and dc actuation voltages from the environment. To fulfill these requirements, viscoelastic materials, such as poly...

  13. Attractive forces in microporous carbon electrodes for capacitive deionization

    Biesheuvel, P. M.; Porada, S.; Levi, M.; Bazant, M.Z.

    2013-01-01

    The recently developed modified Donnan (mD) model provides a simple and useful description of the electrical double layer in microporous carbon electrodes, suitable for incorporation in porous electrode theory. By postulating an attractive excess chemical potential for each ion in the micropores that is inversely proportional to the total ion concentration, we show that experimental data for capacitive deionization (CDI) can be accurately predicted over a wide range of applied voltages and sa...

  14. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials

    Lani, Shane W.; Wasequr Rashid, M.; Hasler, Jennifer; Sabra, Karim G.; Levent Degertekin, F.

    2014-01-01

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally ...

  15. Capacitive Sensors And Targets Would Measure Alignments

    Jenstrom, Del T.

    1994-01-01

    Multiple capacitive sensors and active targets used to measure distance between, and relative orientation of, two objects. Sensed target signals processed and used by control systems to align objects to be joined. Shapes, sizes, and layouts of sensors and targets optimized for specific application. Particular layout of targets and sensors enables determination of relative position and orientation of two objects in all six degrees of freedom.

  16. Water desalination using capacitive deionization with microporous carbon electrodes.

    Porada, S; Weinstein, L; Dash, R; van der Wal, A; Bryjak, M; Gogotsi, Y; Biesheuvel, P M

    2012-03-01

    Capacitive deionization (CDI) is a water desalination technology in which salt ions are removed from brackish water by flowing through a spacer channel with porous electrodes on each side. Upon applying a voltage difference between the two electrodes, cations move to and are accumulated in electrostatic double layers inside the negatively charged cathode and the anions are removed by the positively charged anode. One of the key parameters for commercial realization of CDI is the salt adsorption capacity of the electrodes. State-of-the-art electrode materials are based on porous activated carbon particles or carbon aerogels. Here we report the use for CDI of carbide-derived carbon (CDC), a porous material with well-defined and tunable pore sizes in the sub-nanometer range. When comparing electrodes made with CDC with electrodes based on activated carbon, we find a significantly higher salt adsorption capacity in the relevant cell voltage window of 1.2-1.4 V. The measured adsorption capacity for four materials tested negatively correlates with known metrics for pore structure of the carbon powders such as total pore volume and BET-area, but is positively correlated with the volume of pores of sizes <1 nm, suggesting the relevance of these sub-nanometer pores for ion adsorption. The charge efficiency, being the ratio of equilibrium salt adsorption over charge, does not depend much on the type of material, indicating that materials that have been identified for high charge storage capacity can also be highly suitable for CDI. This work shows the potential of materials with well-defined sub-nanometer pore sizes for energy-efficient water desalination. PMID:22329838

  17. Shunt PWM advanced var compensators based on voltage source inverters for Facts applications

    Barbosa, Pedro G.; Misaka, Isamu; Watanabe, Edson H. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia

    1994-12-31

    Increased attention has been given to improving power system operation. This paper presents modeling, analysis and design of reactive shunt power compensators based on PWM-Voltage Source Inverters (Pulse Width Modulation -Voltage Source Inverters). (Pulse Width Modulation - Voltage Source Inverters). The control algorithm is based on new concepts of instantaneous active and reactive power theory. The objective is to show that with a small capacitor in the side of a 3-phase PWM-VSI it is possible to synthesize a variable reactive (capacitive or inductive) device. Design procedures and experimental results are presented. The feasibility of this method was verified by digital simulations and measurements on a small scale model. (author) 9 refs., 12 figs.

  18. Polymer defect states modulate open-circuit voltage in bulk-heterojunction solar cells

    Defect states influence the operation of organic solar cells altering transport, recombination, and energetic mechanisms. This work investigates how processing conditions induce morphology-related, electrically active defects in the donor polymer of bulk-heterojunction solar cells. Structural order is inferred from absorption and X-ray diffraction data, while defect density is determined from capacitance methods. A correlation is observed between the polymer nanocrystallite size, the defect concentration, and the output voltage. For the case of poly(3-hexylthiophene), processing that promote crystallinity is beneficial for the device performance as it decreases the defect density (energy disorder) that finally enlarges the maximum achievable open-circuit voltage. Defect states within the effective bandgap modulate the downshift of the hole Fermi level upon illumination that in turn establishes the achievable open-circuit voltage

  19. Polymer defect states modulate open-circuit voltage in bulk-heterojunction solar cells

    Ripolles, Teresa S.; Guerrero, Antonio; Garcia-Belmonte, Germà, E-mail: garciag@uji.es [Photovoltaic and Optoelectronic Devices Group, Departament de Física, Universitat Jaume I, ES-12071 Castelló (Spain)

    2013-12-09

    Defect states influence the operation of organic solar cells altering transport, recombination, and energetic mechanisms. This work investigates how processing conditions induce morphology-related, electrically active defects in the donor polymer of bulk-heterojunction solar cells. Structural order is inferred from absorption and X-ray diffraction data, while defect density is determined from capacitance methods. A correlation is observed between the polymer nanocrystallite size, the defect concentration, and the output voltage. For the case of poly(3-hexylthiophene), processing that promote crystallinity is beneficial for the device performance as it decreases the defect density (energy disorder) that finally enlarges the maximum achievable open-circuit voltage. Defect states within the effective bandgap modulate the downshift of the hole Fermi level upon illumination that in turn establishes the achievable open-circuit voltage.

  20. CK2 activity is required for the interaction of FGF14 with voltage-gated sodium channels and neuronal excitability.

    Hsu, Wei-Chun J; Scala, Federico; Nenov, Miroslav N; Wildburger, Norelle C; Elferink, Hannah; Singh, Aditya K; Chesson, Charles B; Buzhdygan, Tetyana; Sohail, Maveen; Shavkunov, Alexander S; Panova, Neli I; Nilsson, Carol L; Rudra, Jai S; Lichti, Cheryl F; Laezza, Fernanda

    2016-06-01

    Recent data shows that fibroblast growth factor 14 (FGF14) binds to and controls the function of the voltage-gated sodium (Nav) channel with phenotypic outcomes on neuronal excitability. Mutations in the FGF14 gene in humans have been associated with brain disorders that are partially recapitulated in Fgf14(-/-) mice. Thus, signaling pathways that modulate the FGF14:Nav channel interaction may be important therapeutic targets. Bioluminescence-based screening of small molecule modulators of the FGF14:Nav1.6 complex identified 4,5,6,7 -: tetrabromobenzotriazole (TBB), a potent casein kinase 2 (CK2) inhibitor, as a strong suppressor of FGF14:Nav1.6 interaction. Inhibition of CK2 through TBB reduces the interaction of FGF14 with Nav1.6 and Nav1.2 channels. Mass spectrometry confirmed direct phosphorylation of FGF14 by CK2 at S228 and S230, and mutation to alanine at these sites modified FGF14 modulation of Nav1.6-mediated currents. In 1 d in vitro hippocampal neurons, TBB induced a reduction in FGF14 expression, a decrease in transient Na(+) current amplitude, and a hyperpolarizing shift in the voltage dependence of Nav channel steady-state inactivation. In mature neurons, TBB reduces the axodendritic polarity of FGF14. In cornu ammonis area 1 hippocampal slices from wild-type mice, TBB impairs neuronal excitability by increasing action potential threshold and lowering firing frequency. Importantly, these changes in excitability are recapitulated in Fgf14(-/-) mice, and deletion of Fgf14 occludes TBB-dependent phenotypes observed in wild-type mice. These results suggest that a CK2-FGF14 axis may regulate Nav channels and neuronal excitability.-Hsu, W.-C. J., Scala, F., Nenov, M. N., Wildburger, N. C., Elferink, H., Singh, A. K., Chesson, C. B., Buzhdygan, T., Sohail, M., Shavkunov, A. S., Panova, N. I., Nilsson, C. L., Rudra, J. S., Lichti, C. F., Laezza, F. CK2 activity is required for the interaction of FGF14 with voltage-gated sodium channels and neuronal

  1. Effect of tunnel structure on the specific capacitance of etched aluminum foil

    Ning Peng; Li-Bo Liang; Ye-Dong He; Hong-Zhou Song; Xiao-Fei Yang; Xiao-Yu Cai

    2014-01-01

    The morphology of etched aluminum foil was observed using scanning electron microscopy, which led to the establishment of a cylindrical model and two merged models, considering the fixed weight loss of etching. The maximum of specific capacitance and the cor-responding optimum values for tunnel sizes at various anodization voltages were predicted. The increased size distribution and taper of tun-nels were demonstrated to decrease the specific capacitance, whereas the addition of polymeric additive into the tunnel widening solution was demonstrated to increase the capacitance. The formation of merged tunnels on the etched aluminum surface, irrespective of the presence of row-merged tunnels or cluster-merged tunnels, resulted in a dramatic decrease in the specific capacitance. It is concluded that, enhancing the uniformity of tunnel size and distribution and avoiding the formation of merged tunnels are the effective approach to achieving the higher capacitance for the tunnel etched and formed aluminum foil.

  2. High-performance feedback-type active damping of LCL-filtered voltage source converters

    Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

    generalized impedance-based model of grid current control with feedback-type active damping. Then, a controller design method based on the z-domain root contours and frequency-domain passivity theorem is proposed. It not only allows a co-design of the grid current controller and damping controller, but...... ensures also a robust stabilization against the grid parameters variations. For illustration, the approach is applied to design three single-state feedback-damping schemes, and their damping robustness are compared under both inductive and resonant grid impedances. Experimental results validate the...

  3. Capacitance multiplier and filter synthesizing network

    Kline, A. J. (Inventor)

    1974-01-01

    A circuit using a differential amplifier multiplies the capacitance of a discrete interating capacitor by (r sub 1 + R sub 2)/R sub 2, where R sub 1 and R sub 2 are values of discrete resistor coupling an input signal e sub 1 of the amplifier inputs. The output e sub 0 of the amplifier is fed back and added to the signal coupled by the resistor R sub 2 to the amplifier through a resistor of value R sub 1. A discrete resistor R sub x may be connected in series for a lag filter, and a discrete resistor may be connected in series with the capacitor for a lead-lag filter. Voltage dividing resistors R sub a and R sub b may be included in the feedback circuit of the amplifier output e sub o to independently adjust the circuit gain e sub i/e sub o.

  4. Design of a 300-Watt Isolated Power Supply with Minimized Circuit Input-to-Output Parasitic Capacitance

    Nguyen-Duy, Khiem; Petersen, Lars Press; Knott, Arnold;

    2014-01-01

    This paper presents the design of a 300-Watt isolated power supply for MOS gate driver circuit in medium and high voltage applications. The key feature of the developed power supply is having a very low circuit input-to-output parasitic capacitance, thus maximizing its noise immunity. This makes it...... suitable for modular stacking applications. The converter is a voltage-controlled current source, utilizing a transformer that has an extremely low inter-winding parasitic capacitance. The experiments show that an overall circuit input-to-output parasitic capacitance of 10 pF can be achieved. Design...

  5. Estimation of carrier mobility at organic semiconductor/insulator interface using an asymmetric capacitive test structure

    Rajesh Agarwal

    2016-04-01

    Full Text Available Mobility of carriers at the organic/insulator interface is crucial to the performance of organic thin film transistors. The present work describes estimation of mobility using admittance measurements performed on an asymmetric capacitive test structure. Besides the advantage of simplicity, it is shown that at low frequencies, the measured capacitance comes from a large area of channel making the capacitance-voltage characteristics insensitive to contact resistances. 2-D numerical simulation and experimental results obtained with Pentacene/Poly(4-vinyphenol system are presented to illustrate the operation and advantages of the proposed technique.

  6. Estimation of carrier mobility at organic semiconductor/insulator interface using an asymmetric capacitive test structure

    Agarwal, Rajesh; Agarwal, Ashish K.; Mazhari, Baquer

    2016-04-01

    Mobility of carriers at the organic/insulator interface is crucial to the performance of organic thin film transistors. The present work describes estimation of mobility using admittance measurements performed on an asymmetric capacitive test structure. Besides the advantage of simplicity, it is shown that at low frequencies, the measured capacitance comes from a large area of channel making the capacitance-voltage characteristics insensitive to contact resistances. 2-D numerical simulation and experimental results obtained with Pentacene/Poly(4-vinyphenol) system are presented to illustrate the operation and advantages of the proposed technique.

  7. Dynamic regulation of mechanosensitive channels: capacitance used to monitor patch tension in real time

    Suchyna, Thomas M.; Besch, Steven R.; Sachs, Frederick

    2004-03-01

    All cells, from bacteria to human, are mechanically sensitive. The most rapid of these membrane protein transducers are mechanosensitive ion channels, ionic pores in the membrane that open and close in response to membrane tension. In specific sensory organs, these channels serve the senses of touch and hearing, and inform the central nervous system about the filling of hollow organs such as the bladder. Non-specialized cells use these channels to report on changes in cell volume and local strain. To preserve dynamic sensitivity, sensory receptors adapt to steady-state stimuli. Here we show that in rat astrocytes, the most abundant cells in the brain, this apparent adaptation to the stimulus is actually an inactivation. We have been able to track the time course of local strain by measuring attofarad changes in membrane capacitance and show that it is not correlated with loss of channel activity. The reduction in current with time is caused by an increased occupancy of low conductance states, and a reduction in the probability of opening, not a relaxation of local stress. The occupancy of these substates depends on the integrity of the cell's cytoplasm. However, while disruption of the cytoskeleton leads to a loss of inactivation, it leaves activation unaffected. The activation process is voltage-insensitive, closely correlated with changes in capacitance, and seems to arise solely from stress in the bilayer. The inactivation rate decreases with depolarization, and kinetic analysis suggests that the process involves multiple cytoplasmic ligands. Surprisingly, multivalent ions such as Gd+3 and Ca+2 that bind to the lipids and affect channel gating, do not affect the strain-induced increase in membrane capacitance; contrary to expectations, membrane elasticity is unchanged.

  8. Long-Term Spatiotemporal Reconfiguration of Neuronal Activity Revealed by Voltage-Sensitive Dye Imaging in the Cerebellar Granular Layer.

    Gandolfi, Daniela; Mapelli, Jonathan; D'Angelo, Egidio

    2015-01-01

    Understanding the spatiotemporal organization of long-term synaptic plasticity in neuronal networks demands techniques capable of monitoring changes in synaptic responsiveness over extended multineuronal structures. Among these techniques, voltage-sensitive dye imaging (VSD imaging) is of particular interest due to its good spatial resolution. However, improvements of the technique are needed in order to overcome limits imposed by its low signal-to-noise ratio. Here, we show that VSD imaging can detect long-term potentiation (LTP) and long-term depression (LTD) in acute cerebellar slices. Combined VSD imaging and patch-clamp recordings revealed that the most excited regions were predominantly associated with granule cells (GrCs) generating EPSP-spike complexes, while poorly responding regions were associated with GrCs generating EPSPs only. The correspondence with cellular changes occurring during LTP and LTD was highlighted by a vector representation obtained by combining amplitude with time-to-peak of VSD signals. This showed that LTP occurred in the most excited regions lying in the core of activated areas and increased the number of EPSP-spike complexes, while LTD occurred in the less excited regions lying in the surround. VSD imaging appears to be an efficient tool for investigating how synaptic plasticity contributes to the reorganization of multineuronal activity in neuronal circuits. PMID:26294979

  9. Long-Term Spatiotemporal Reconfiguration of Neuronal Activity Revealed by Voltage-Sensitive Dye Imaging in the Cerebellar Granular Layer

    Daniela Gandolfi

    2015-01-01

    Full Text Available Understanding the spatiotemporal organization of long-term synaptic plasticity in neuronal networks demands techniques capable of monitoring changes in synaptic responsiveness over extended multineuronal structures. Among these techniques, voltage-sensitive dye imaging (VSD imaging is of particular interest due to its good spatial resolution. However, improvements of the technique are needed in order to overcome limits imposed by its low signal-to-noise ratio. Here, we show that VSD imaging can detect long-term potentiation (LTP and long-term depression (LTD in acute cerebellar slices. Combined VSD imaging and patch-clamp recordings revealed that the most excited regions were predominantly associated with granule cells (GrCs generating EPSP-spike complexes, while poorly responding regions were associated with GrCs generating EPSPs only. The correspondence with cellular changes occurring during LTP and LTD was highlighted by a vector representation obtained by combining amplitude with time-to-peak of VSD signals. This showed that LTP occurred in the most excited regions lying in the core of activated areas and increased the number of EPSP-spike complexes, while LTD occurred in the less excited regions lying in the surround. VSD imaging appears to be an efficient tool for investigating how synaptic plasticity contributes to the reorganization of multineuronal activity in neuronal circuits.

  10. Electrodic voltages in the presence of dissolved sulfide: Implications for monitoring natural microbial activity

    Slater, L.; Ntarlagiannis, D.; Yee, N.; O' Brien, M.; Zhang, C.; Williams, K. H.

    2008-10-01

    There is growing interest in the development of new monitoring strategies for obtaining spatially extensive data diagnostic of microbial processes occurring in the earth. Open-circuit potentials arising from variable redox conditions in the fluid local-to-electrode surfaces (electrodic potentials) were recorded for a pair of silver-silver chloride electrodes in a column experiment, whereby a natural wetland soil containing a known community of sulfate reducers was continuously fed with a sulfate-rich nutrient medium. Measurements were made between five electrodes equally spaced along the column and a reference electrode placed on the column inflow. The presence of a sulfate reducing microbial population, coupled with observations of decreasing sulfate levels, formation of black precipitate (likely iron sulfide),elevated solid phase sulfide, and a characteristic sulfurous smell, suggest microbial-driven sulfate reduction (sulfide generation) in our column. Based on the known sensitivity of a silver electrode to dissolved sulfide concentration, we interpret the electrodic potentials approaching 700 mV recorded in this experiment as an indicator of the bisulfide (HS-) concentration gradients in the column. The measurement of the spatial and temporal variation in these electrodic potentials provides a simple and rapid method for monitoring patterns of relative HS- concentration that are indicative of the activity of sulfate-reducing bacteria. Our measurements have implications both for the autonomous monitoring of anaerobic microbial processes in the subsurface and the performance of self-potential electrodes, where it is critical to isolate, and perhaps quantify, electrochemical interfaces contributing to observed potentials.

  11. Capacitive Position Sensor For Accelerometer

    Vanzandt, Thomas R.; Kaiser, William J.; Kenny, Thomas W.

    1995-01-01

    Capacitive position sensor measures displacement of proof mass in prototype accelerometer described in "Single-Crystal Springs for Accelerometers" (NPO-18795). Sensor is ultrasensitive, miniature device operating at ultra-high frequency and described in more detail in "Ultra-High-Frequency Capacitive Displacement Sensor," (NPO-18675). Advances in design and fabrication of prototype accelerometer also applicable to magnetometers and other sensors in which sensed quantities measured in terms of deflections of small springs.

  12. Coordinated role of voltage-gated sodium channels and the Na+/H+ exchanger in sustaining microglial activation during inflammation

    Persistent neuroinflammation and microglial activation play an integral role in the pathogenesis of many neurological disorders. We investigated the role of voltage-gated sodium channels (VGSC) and Na+/H+ exchangers (NHE) in the activation of immortalized microglial cells (BV-2) after lipopolysaccharide (LPS) exposure. LPS (10 and 100 ng/ml) caused a dose- and time-dependent accumulation of intracellular sodium [(Na+)i] in BV-2 cells. Pre-treatment of cells with the VGSC antagonist tetrodotoxin (TTX, 1 μM) abolished short-term Na+ influx, but was unable to prevent the accumulation of (Na+)i observed at 6 and 24 h after LPS exposure. The NHE inhibitor cariporide (1 μM) significantly reduced accumulation of (Na+)i 6 and 24 h after LPS exposure. Furthermore, LPS increased the mRNA expression and protein level of NHE-1 in a dose- and time-dependent manner, which was significantly reduced after co-treatment with TTX and/or cariporide. LPS increased production of TNF-α, ROS, and H2O2 and expression of gp91phox, an active subunit of NADPH oxidase, in a dose- and time-dependent manner, which was significantly reduced by TTX or TTX + cariporide. Collectively, these data demonstrate a closely-linked temporal relationship between VGSC and NHE-1 in regulating function in activated microglia, which may provide avenues for therapeutic interventions aimed at reducing neuroinflammation. - Highlights: • LPS causes immediate increase in sodium through VGSC and subsequently through the NHE-1. • Inhibition of VGSC reduces increases in NHE-1 and gp91phox. • Inhibition of VGSC and NHE-1 reduces NADPH oxidase-mediated Tnf-α, ROS, and H2O2 production. • NHE-1 and Nav1.6 may be viable targets for therapeutic interventions to reduce neuroinflammation in neurodegenerative disease

  13. Ca2+- and voltage-gated potassium (BK) channel activators in the 5β-cholanic acid-3α-ol analogue series with modifications in lateral chain

    Bukiya, Anna N.; Patil, Shivaputra; Li, Wei; Miller, Duane; Dopico, Alex M.

    2012-01-01

    Large conductance, calcium- and voltage-gated potassium (BK) channels regulate various physiological processes and represent an attractive target for drug discovery. Numerous BK channel activators are available. However, these agents usually interact with the ubiquitously distributed channel-forming subunit and thus cannot selectively target a particular tissue. Here, we performed structure-activity relationship study of lithocholic acid (LCA), a cholane that activates BK channels via the acc...

  14. Development of capacitive micromachined ultrasonic transducer for noncontact ultrasonic detection

    In this study, the capacitive micromachined ultrasonic transducer (cMUT) was developed. Theoretical analysis and finite element analysis of the behavior of membrane (such as resonance frequency, membrane deflection, collapse deflection and collapse voltage) of the cMUT were performed. The design parameters of the cMUT were estimated and are the dimension and thickness of membrane, thickness of sacrificial layer, thickness and size of electrode, size of active element and so on. With the micro-fabrication process, the cMUT was fabricated on the silicon wafer. To measure the membrane displacement of cMUT, the Michelson phase modulation fiber interferometer was constructed. The measured membrane displacement was good agreed with the result of finite element analysis. To estimate the ultrasonic wave generated by the cMUT, the ultrasonic transceiver system was constructed. The developed cMUT shows a good performance and hence will be widely used to the filed of non-contact ultrasonic application.

  15. Carbon electrode for desalination purpose in capacitive deionization

    Endarko, Fadilah, Nurul; Anggoro, Diky

    2016-03-01

    Carbon electrodes for desalination purpose have been successfully synthesized using activated carbon powder (BET surface area=700 - 1400 m2/g), carbon black and polyvinyl alcohol (PVA) binder by cross-linking method with glutaric acid (GA) at 120 °C. The electrochemical properties of the carbon electrodes were analyzed using electrical impedance spectroscopy (EIS) and cyclic voltammetry (CV) whilst the physical properties were observed with scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX). In order to assess the desalting performance, salt removal experiments were performed by constructing a capacitive deionization unit cell with five pairs of carbon electrodes. For each pair consisted of two parallel carbon electrodes separated by a spacer. Desalination and regeneration processes were also observed in the salt-removal experiments. The salt-removal experiments were carried out in single-pass mode using a solution with 0.1 M NaCl at a flow rate of 10 mL/min. A voltage of 3 V was applied to the cell for 60 minutes for both processes in desalination and regeneration. The result showed that the percentage value of the salt-removal was achieved at 20%.

  16. The concept of chemical capacitance, A critique.

    Trissl, H. W.

    1981-01-01

    The concept of chemical capacitance as introduced by Hong and Mauzerall (Proc. Natl. Acad. Sci. U.S.A. 1974. 71:1564) is critically reexamined. This novel capacitance was introduced to explain the time-course of flash-induced photocurrents observed in lipid bilayer membranes containing porphyrins. According to Hong and Mauzerall, the chemical capacitance results from a combination of three fundamental capacitances: the geometric membrane capacitance and the two interfacial double layer capaci...

  17. Capacitance estimation for InAs Tunnel FETs by means of full-quantum k · p simulation

    Gnani, E.; Baravelli, E.; Gnudi, A.; Reggiani, S.; Baccarani, G.

    2015-06-01

    We report for the first time a quantum mechanical simulation study of gate capacitance components in aggressively scaled InAs Nanowire Tunnel Field-Effect Transistors. It will be shown that the gate-drain capacitance exhibits the same functional dependence over the whole Vgs range as the total gate capacitance, albeit with smaller values. However, as opposed to the previous capacitance estimations provided by semiclassical TCAD tools, we find that the gate capacitance exhibits a non-monotonic behavior vs. gate voltage, with plateaus and bumps related with energy quantization and subband formation determined by the device cross-sectional size, as well as with the position of channel-conduction subbands relative to the Fermi level in the drain contact. From this point of view, semiclassical TCAD tools seem to be inaccurate for capacitance estimation in aggressively-scaled TFET devices.

  18. Mild Alkalization Acutely Triggers the Warburg Effect by Enhancing Hexokinase Activity via Voltage-Dependent Anion Channel Binding

    Lee, Jin Hee; Park, Jin Won; Moon, Seung Hwan; Cho, Young Seok; Choe, Yearn Seong; Lee, Kyung-Han

    2016-01-01

    To fully understand the glycolytic behavior of cancer cells, it is important to recognize how it is linked to pH dynamics. Here, we evaluated the acute effects of mild acidification and alkalization on cancer cell glucose uptake and glycolytic flux and investigated the role of hexokinase (HK). Cancer cells exposed to buffers with graded pH were measured for 18F-fluorodeoxyglucose (FDG) uptake, lactate production and HK activity. Subcellular localization of HK protein was assessed by western blots and confocal microscopy. The interior of T47D breast cancer cells was mildly alkalized to pH 7.5 by a buffer pH of 7.8, and this was accompanied by rapid increases of FDG uptake and lactate extrusion. This shift toward glycolytic flux led to the prompt recovery of a reversed pH gradient. In contrast, mild acidification rapidly reduced cellular FDG uptake and lactate production. Mild acidification decreased and mild alkalization increased mitochondrial HK translocation and enzyme activity. Cells transfected with specific siRNA against HK-1, HK-2 and voltage-dependent anion channel (VDAC)1 displayed significant attenuation of pH-induced changes in FDG uptake. Confocal microscopy showed increased co-localization of HK-1 and HK-2 with VDAC1 by alkaline treatment. In isolated mitochondria, acidic pH increased and alkaline pH decreased release of free HK-1 and HK-2 from the mitochondrial pellet into the supernatant. Furthermore, experiments using purified proteins showed that alkaline pH promoted co-immunoprecipitation of HK with VDAC protein. These findings demonstrate that mild alkalization is sufficient to acutely trigger cancer cell glycolytic flux through enhanced activity of HK by promoting its mitochondrial translocation and VDAC binding. This process might serve as a mechanism through which cancer cells trigger the Warburg effect to maintain a dysregulated pH. PMID:27479079

  19. Negativity of the excess noise in a quantum wire capacitively coupled to a gate

    Dolcini, Fabrizio

    2007-01-01

    The electrical current noise of a quantum wire is expected to increase with increasing applied voltage. We show that this intuition can be wrong. Specifically, we consider a single-channel quantum wire with impurities and with a capacitive coupling to nearby metallic gates and find that its excess noise, defined as the change in the noise caused by the finite voltage, can be negative at zero temperature. This feature is present both for large (c⪢cq) and small (c⪡cq) capacitive coupling, where...

  20. Negativity of the excess noise in a quantum wire capacitively coupled to a gate

    Dolcini, F.; Trauzettel, B.; Safi, I.; Grabert, H.

    2006-01-01

    The electrical current noise of a quantum wire is expected to increase with increasing applied voltage. We show that this intuition can be wrong. Specifically, we consider a single channel quantum wire with impurities and with a capacitive coupling to nearby metallic gates and find that its excess noise, defined as the change in the noise caused by the finite voltage, can be negative at zero temperature. This feature is present both for large ($c \\gg c_q$) and small ($c \\ll c_q$) capacitive c...

  1. Capacitance-frequency Spectrum Characterization of Organics/Metal Schottky Diodes

    GUO Wen-ge; ZHANG Yan-cao; ZHANG Shou-gang

    2006-01-01

    An organics/metal Schottky diode is fabricated using 3, 4∶9, 10-perylenetetracarboxylic-dianhydride(PTCDA) thin film sandwiched between ITO and Au by simple thermal evaporation technique. The current-voltage(I-V) characteristics are investigated at room temperature in open air. The results show the rectification ratio is in excess of 100. From the capacitance-frequency(C-f) and capacitance-voltage(C-V) measurements, the Schottky barrier height between 0.2~0.3 eV is obtained according to standard Schottky theory.

  2. Development of Flexible Capacitive Ultrasound Transducers and the Use of Ultrasound for Bone Repair

    Wentzell, Scott A.

    Ultrasound is a widely applicable technique for therapy in the biomedical arena. However, conventional ultrasound transducers are not conducive for non-planar surfaces. Therefore, we developed flexible transducers capable of performing ultrasound and evaluated their use in biomedical applications. Flexible capacitive ultrasound transducers based on micrometer-thick dielectric tapes were developed and fabricated. These transducers were able to be made by hand at low-cost while still demonstrating good tolerances in center operating frequency. Intensities of up to 120 mW/cm2 were recorded and operation was dependent upon the applied AC and DC voltages along with the thickness of the dielectric insulation. These capacitive ultrasound transducers were used to stimulate MC3T3-E1 murine osteoblast cells to investigate the effects of low-frequency ultrasound on osteogenic gene expression and anabolic signaling pathways. After stimulation by 94.5 kHz continuous wave ultrasound for 20 minutes, significant increases in the activation of the Wnt signaling pathway and concentration of intracellular calcium were observed. Daily stimulation by ultrasound showed a trend of increased osteogenic gene expression across the phases of matrix deposition, maturation and calcification by osteoblasts. Finally, the heating of osteoblasts for stimulating osteoclastogenic responses was investigated. The application of increased temperatures of 42 and 47 degrees Celsius for 5 minutes showed significant increases in the RANKL/OPG ratio in media conditioned by osteoblasts. However, the altered RANKL/OPG ratio was not able to generate increases in osteoclastogenesis for RAW 264.7 murine macrophage cells culture in the condition media. This was possibly due to high overall osteoprotegerin expression, or unwanted inducement of M1 and M2 macrophage activation in the cell population. The overall work of this thesis demonstrates the development of novel capacitive transducers. These conformable

  3. Capacitance properties and simulation of the AlGaN/GaN Schottky heterostructure

    Harmatha, Ladislav, E-mail: ladislav.harmatha@stuba.sk; Ľubica, Stuchlíková; Juraj, Racko; Juraj, Marek; Juraj, Pecháček; Peter, Benko; Michal, Nemec; Juraj, Breza

    2014-09-01

    Highlights: • Dependences of CV characteristics of the AlGaN/GaN structure on frequency and temperature variations. • Identification of electrical activity of defects by capacitance DLTS. • Simulating the properties of the GaN/Al{sub 0.2}GaN{sub 0.8}/GaN Schottky heterostructure. - Abstract: The paper presents the results of capacitance measurements on GaN/AlGaN/GaN Schottky heterostructures grown on an Al{sub 2}O{sub 3} substrate by Low-Pressure Metal–Organic Vapour-Phase Epitaxy (LP-MOVPE). Dependences of the capacitance–voltage (CV) characteristics on the frequency of the measuring signal allow analysing the properties of the 2D electron gas (2DEG) at the AlGaN/GaN heterojunction. Exact location of the hetero-interface below the surface (20 nm) was determined from the concentration profile. Temperature variations of the CV curves reveal the influence of bulk defects in GaN and of the traps at the AlGaN/GaN interface. Electrical activity of these defects was characterized by capacitance Deep Level Transient Fourier Spectroscopy (DLTFS). Experimental results of CV measurements were supported by simulating the properties of the GaN/Al{sub 0.2}GaN{sub 0.8}/GaN Schottky heterostructure in dependence on the influence of the concentration of donor-like traps in GaN and of the temperature upon the CV curves.

  4. The power output and efficiency of a negative capacitance shunt for vibration control of a flexural system

    A negative capacitance shunt is a basic, analog, active circuit electrically connected to a piezoelectric transducer to control the vibrations of flexural bodies. The shunt circuit consists of a resistor and a synthetic negative capacitor to introduce a real and imaginary impedance on a vibrating mechanical system. The electrical impedance of the negative capacitance shunt modifies the effective modulus of the piezoelectric transducer to reduce the stiffness and increase the damping, which causes a decrease in amplitude of the vibrating structure to which the elements are bonded. To gain an insight into the electromechanical coupling and power output, the shunt and the electrical properties of the piezoelectric transducer are modeled using circuit modeling software. The power output of the model is validated with experimental measurements of a shunt connected to a piezoelectric transducer pair bonded to a vibrating aluminum cantilever beam. The model is used to select the passive components of the negative capacitance shunt to increase the efficiency and quantify the voltage output limit of the op-amp. (paper)

  5. Electro-removal of arsenic(III) and arsenic(V) from aqueous solutions by capacitive deionization.

    Fan, Chen-Shiuan; Tseng, Ssu-Chia; Li, Kung-Cheh; Hou, Chia-Hung

    2016-07-15

    The feasibility of the electro-removal of arsenate (As(V)) and arsenite (As(III)) from aqueous solutions via capacitive deionization was investigated. The effects of applied voltage (0.0-1.2V) and initial concentration (0.1-200mgL(-1)) on arsenic removal were examined. As evidenced, an enhancement of arsenic removal can be achieved by capacitive deionization. The capacity to remove As(V) at an initial concentration of 0.2mgL(-1) on the activated carbon electrode at 1.2V was determined to be 2.47×10(-2)mgg(-1), which is 1.8-fold higher than that of As(III) (1.37×10(-2)mgg(-1)). Notably, the possible transformation of arsenic species was further characterized. The higher effectiveness of As(V) removal via electrosorption at 1.2V was attributed to the formation of an electrical double layer at the electrode/solution interface. The removal of As(III) could be achieved by the oxidation of As(III) to As(V) and subsequent electrosorption of the As(V) onto the electrode surface of the anode. The presence of sodium chloride or natural organic matter was found to considerably decrease arsenic removal. Single-pass electrosorption-desorption experiments conducted at 1.2V further demonstrated that capacitive deionization is a potential means of effectively removing arsenic from aqueous solutions. PMID:27037475

  6. Antimigraine drug, zolmitriptan, inhibits high-voltage activated calcium currents in a population of acutely dissociated rat trigeminal sensory neurons

    Matsuzawa Yoshiyasu

    2006-03-01

    Full Text Available Abstract Background Triptans, 5-HT1B/ID agonists, act on peripheral and/or central terminals of trigeminal ganglion neurons (TGNs and inhibit the release of neurotransmitters to second-order neurons, which is considered as one of key mechanisms for pain relief by triptans as antimigraine drugs. Although high-voltage activated (HVA Ca2+ channels contribute to the release of neurotransmitters from TGNs, electrical actions of triptans on the HVA Ca2+ channels are not yet documented. Results In the present study, actions of zolmitriptan, one of triptans, were examined on the HVA Ca2+ channels in acutely dissociated rat TGNs, by using whole-cell patch recording of Ba2+ currents (IBa passing through Ca2+ channels. Zolmitriptan (0.1–100 μM reduced the size of IBa in a concentration-dependent manner. This zolmitriptan-induced inhibitory action was blocked by GR127935, a 5-HT1B/1D antagonist, and by overnight pretreatment with pertussis toxin (PTX. P/Q-type Ca2+ channel blockers inhibited the inhibitory action of zolmitriptan on IBa, compared to N- and L-type blockers, and R-type blocker did, compared to L-type blocker, respectively (p 1B/1D receptor linked to Gi/o pathway. Conclusion It is concluded that this zolmitriptan inhibition of HVA Ca2+ channels may explain the reduction in the release of neurotransmitters including CGRP, possibly leading to antimigraine effects of zolmitriptan.

  7. Spexin Enhances Bowel Movement through Activating L-type Voltage-dependent Calcium Channel via Galanin Receptor 2 in Mice

    Lin, Cheng-yuan; Zhang, Man; Huang, Tao; Yang, Li-ling; Fu, Hai-bo; Zhao, Ling; Zhong, Linda LD; Mu, Huai-xue; Shi, Xiao-ke; Leung, Christina FP; Fan, Bao-min; Jiang, Miao; Lu, Ai-ping; Zhu, Li-xin; Bian, Zhao-xiang

    2015-01-01

    A novel neuropeptide spexin was found to be broadly expressed in various endocrine and nervous tissues while little is known about its functions. This study investigated the role of spexin in bowel movement and the underlying mechanisms. In functional constipation (FC) patients, serum spexin levels were significantly decreased. Consistently, in starved mice, the mRNA of spexin was significantly decreased in intestine and colon. Spexin injection increased the velocity of carbon powder propulsion in small intestine and decreased the glass beads expulsion time in distal colon in mice. Further, spexin dose-dependently stimulated the intestinal/colonic smooth muscle contraction. Galanin receptor 2 (GALR2) antagonist M871, but not Galanin receptor 3 (GALR3) antagonist SNAP37899, effectively suppressed the stimulatory effects of spexin on intestinal/colonic smooth muscle contraction, which could be eliminated by extracellular [Ca2+] removal and L-type voltage-dependentCa2+ channel (VDCC) inhibitor nifedipine. Besides, spexin dramatically increased the [Ca2+]i in isolated colonic smooth muscle cells. These data indicate that spexin can act on GALR2 receptor to regulate bowel motility by activating L-type VDCC. Our findings provide evidence for important physiological roles of spexin in GI functions. Selective action on spexin pathway might have therapeutic effects on GI diseases with motility disorders. PMID:26160593

  8. Extracellular signal-regulated kinases modulate capacitation of human spermatozoa.

    Luconi, M; Barni, T; Vannelli, G B; Krausz, C; Marra, F; Benedetti, P A; Evangelista, V; Francavilla, S; Properzi, G; Forti, G; Baldi, E

    1998-06-01

    Recent evidence indicates the presence of p21 Ras and of a protein with characteristics similar to mitogen-activated protein kinases (MAPKs), also known as extracellular signal-regulated kinases (ERKs), in mammalian spermatozoa, suggesting the occurrence of the Ras/ERK cascade in these cells. In the present study we investigated the subcellular localization of ERKs and their biological functions in human spermatozoa. Immunohistochemistry, immunofluorescence, confocal microscopy, and immunoelectron microscopy demonstrated localization of ERKs in the postacrosomal region of spermatozoa. After stimulation of acrosome reaction with the calcium ionophore A23187 and progesterone, ERKs were mostly localized at the level of the equatorial region, indicating redistribution of these proteins in acrosome-reacted spermatozoa. Two proteins of 42 and 44 kDa that are tyrosine phosphorylated in a time-dependent manner during in vitro capacitation were identified as p42 (ERK-2) and p44 (ERK-1) by means of specific antibodies. The increase in tyrosine phosphorylation of these proteins during capacitation was accompanied by increased kinase activity, as determined by the ability of ERK-1 and ERK-2 to phosphorylate the substrate myelin basic protein. The role of this activity in the occurrence of sperm capacitation was also investigated by using PD098059, an inhibitor of the MAPK cascade. The presence of this compound during in vitro capacitation inhibits ERK activation and significantly reduces the ability of spermatozoa to undergo the acrosome reaction in response to progesterone. Since only capacitated spermatozoa are able to respond to progesterone, these data strongly indicate that ERKs are involved in the regulation of capacitation. In summary, our data demonstrate the presence of functional ERKs in human spermatozoa and indicate that these enzymes are involved in activation of these cells during capacitation, providing new insight in clarifying the molecular mechanisms and the

  9. Performance enhancement of the single-phase series active filter by employing the load voltage waveform reconstruction and line current sampling delay reduction methods

    Senturk, O.S.; Hava, A.M.

    2011-01-01

    This paper proposes the waveform reconstruction method (WRM), which is utilized in the single-phase series active filter's (SAF's) control algorithm, in order to extract the load harmonic voltage component of voltage harmonic type single-phase diode rectifier loads. Employing WRM and the line...... current sampling delay reduction method, a single-phase SAF compensated system provides higher harmonic isolation performance and higher stability margins compared to the system using conventional synchronous-reference-frame-based methods. The analytical, simulation, and experimental studies of a 2.5 k......W single-phase SAF compensated system prove the theory....

  10. Regionally specific expression of high-voltage-activated calcium channels in thalamic nuclei of epileptic and non-epileptic rats.

    Kanyshkova, Tatyana; Ehling, Petra; Cerina, Manuela; Meuth, Patrick; Zobeiri, Mehrnoush; Meuth, Sven G; Pape, Hans-Christian; Budde, Thomas

    2014-07-01

    The polygenic origin of generalized absence epilepsy results in dysfunction of ion channels that allows the switch from physiological asynchronous to pathophysiological highly synchronous network activity. Evidence from rat and mouse models of absence epilepsy indicates that altered Ca(2+) channel activity contributes to cellular and network alterations that lead to seizure activity. Under physiological circumstances, high voltage-activated (HVA) Ca(2+) channels are important in determining the thalamic firing profile. Here, we investigated a possible contribution of HVA channels to the epileptic phenotype using a rodent genetic model of absence epilepsy. In this study, HVA Ca(2+) currents were recorded from neurons of three different thalamic nuclei that are involved in both sensory signal transmission and rhythmic-synchronized activity during epileptic spike-and-wave discharges (SWD), namely the dorsal part of the lateral geniculate nucleus (dLGN), the ventrobasal thalamic complex (VB) and the reticular thalamic nucleus (NRT) of epileptic Wistar Albino Glaxo rats from Rijswijk (WAG/Rij) and non-epileptic August Copenhagen Irish (ACI) rats. HVA Ca(2+) current densities in dLGN neurons were significantly increased in epileptic rats compared with non-epileptic controls while other thalamic regions revealed no differences between the strains. Application of specific channel blockers revealed that the increased current was carried by L-type Ca(2+) channels. Electrophysiological evidence of increased L-type current correlated with up-regulated mRNA and protein expression of a particular L-type channel, namely Cav1.3, in dLGN of epileptic rats. No significant changes were found for other HVA Ca(2+) channels. Moreover, pharmacological inactivation of L-type Ca(2+) channels results in altered firing profiles of thalamocortical relay (TC) neurons from non-epileptic rather than from epileptic rats. While HVA Ca(2+) channels influence tonic and burst firing in ACI and WAG

  11. Thermodynamic cycle analysis for capacitive deionization.

    Biesheuvel, P M

    2009-04-01

    Capacitive deionization (CDI) is an ion removal technology based on temporarily storing ions in the polarization layers of two oppositely positioned electrodes. Here we present a thermodynamic model for the minimum work required for ion separation in the fully reversible case by describing the ionic solution as an ideal gas of pointlike particles. The work input is fully utilized to decrease the entropy of the outflowing streams compared to that of the inflow. Based on the Gouy-Chapman-Stern (GCS) model for planar diffuse polarization layers-with and without including additional ion volume constraints in the diffuse part of the double layer-we analyze the electric work input during charging and the work output during discharging, for a reversible charging-discharging cycle. We present a graphical thermodynamic cycle analysis for the reversible net work input during one full cycle of batchwise operation of CDI based on the charge-voltage relations for different ionic strengths. For the GCS model, an analytical solution is derived for the charge efficiency Lambda, which is the number of salt molecules removed per electron transferred from one electrode to the other. Only in the high voltage limit and for an infinite Stern layer capacity does Lambda approach unity. PMID:19167009

  12. Comparison of two voltage-sensitive dyes and their suitability for long-term imaging of neuronal activity.

    Stephanie Preuss

    Full Text Available One of the key approaches for studying neural network function is the simultaneous measurement of the activity of many neurons. Voltage-sensitive dyes (VSDs simultaneously report the membrane potential of multiple neurons, but often have pharmacological and phototoxic effects on neuronal cells. Yet, to study the homeostatic processes that regulate neural network function long-term recordings of neuronal activities are required. This study aims to test the suitability of the VSDs RH795 and Di-4-ANEPPS for optically recording pattern generating neurons in the stomatogastric nervous system of crustaceans with an emphasis on long-term recordings of the pyloric central pattern generator. We demonstrate that both dyes stain pyloric neurons and determined an optimal concentration and light intensity for optical imaging. Although both dyes provided sufficient signal-to-noise ratio for measuring membrane potentials, Di-4-ANEPPS displayed a higher signal quality indicating an advantage of this dye over RH795 when small neuronal signals need to be recorded. For Di-4-ANEPPS, higher dye concentrations resulted in faster and brighter staining. Signal quality, however, only depended on excitation light strength, but not on dye concentration. RH795 showed weak and slowly developing phototoxic effects on the pyloric motor pattern as well as slow bleaching of the staining and is thus the better choice for long-term experiments. Low concentrations and low excitation intensities can be used as, in contrast to Di-4-ANEPPS, the signal-to-noise ratio was independent of excitation light strength. In summary, RH795 and Di-4-ANEPPS are suitable for optical imaging in the stomatogastric nervous system of crustaceans. They allow simultaneous recording of the membrane potential of multiple neurons with high signal quality. While Di-4-ANEPPS is better suited for short-term experiments that require high signal quality, RH795 is a better candidate for long-term experiments

  13. Improvement of Ground-Fault Relaying Selectivity through the Application of Directional Relays to High-Voltage Longwall Mining Systems

    Basar, Joseph James

    2004-01-01

    The continuing trend toward larger longwall mining systems has resulted in the utilization of higher system voltages. The increase in system voltage levels has caused the industry to face complexities not experienced with the lower-voltage systems. One such complexity arises from the larger system capacitance that results from the outby configuration commonly used on 4,160-V longwall power systems. Simulations show that during a line-to-ground fault, the larger system capacitance can cause...

  14. Simulation of Reactive Power Imbalances in the Transmission Power Grid Threatened by the Problem of Voltage Instability

    Robert Lis; Mirosław Łabuzek

    2013-01-01

    The reactive power balance in the transmission power grid depends on the reactive power produced by the power stations and the value generated by the capacitive power lines and static compensators. Reactive transmission losses become greater than shunt capacitive generation at the turning-point of voltage stability. Then lowering bus voltages drive EPS into voltage collapse point. The paper presents the balance of reactive power depending on the power demand growth, which is then used to esti...

  15. Low-Noise Large-Area Photoreceivers with Low Capacitance Photodiodes

    Joshi, Abhay M. (Inventor); Datta, Shubhashish (Inventor)

    2013-01-01

    A quad photoreceiver includes a low capacitance quad InGaAs p-i-n photodiode structure formed on an InP (100) substrate. The photodiode includes a substrate providing a buffer layer having a metal contact on its bottom portion serving as a common cathode for receiving a bias voltage, and successive layers deposited on its top portion, the first layer being drift layer, the second being an absorption layer, the third being a cap layer divided into four quarter pie shaped sections spaced apart, with metal contacts being deposited on outermost top portions of each section to provide output terminals, the top portions being active regions for detecting light. Four transimpedance amplifiers have input terminals electrically connected to individual output terminals of each p-i-n photodiode.

  16. Bupivacaine inhibits large conductance, voltage- and Ca2+- activated K+ channels in human umbilical artery smooth muscle cells

    Martín, Pedro; Enrique, Nicolás; Palomo, Ana R. Roldán; Rebolledo, Alejandro; Milesi, Veronica

    2012-01-01

    Bupivacaine is a local anesthetic compound belonging to the amino amide group. Its anesthetic effect is commonly related to its inhibitory effect on voltage-gated sodium channels. However, several studies have shown that this drug can also inhibit voltage-operated K+ channels by a different blocking mechanism. This could explain the observed contractile effects of bupivacaine on blood vessels. Up to now, there were no previous reports in the literature about bupivacaine effects on large condu...

  17. Control of Active Front-End Rectifier in Electric Drive under Unbalanced Voltage Supply in Transient States

    Chomát, Miroslav; Schreier, Luděk; Bendl, Jiří

    2012-01-01

    Roč. 88, 1A (2012), s. 177-180. ISSN 0033-2097 R&D Projects: GA ČR GA102/09/1273 Institutional research plan: CEZ:AV0Z20570509 Keywords : unbalanced voltage supply * DC-link voltage pulsations * pulse-width modulation Subject RIV: JA - Electronic s ; Optoelectronics, Electrical Engineering Impact factor: 0.244, year: 2011 http://www.red.pe.org.pl/abstract_pl.php?nid=5479

  18. Estimation of Transformer Parameters and Loss Analysis for High Voltage Capacitor Charging Application

    Thummala, Prasanth; Schneider, Henrik; Ouyang, Ziwei;

    2013-01-01

    In a bi-directional DC-DC converter for capacitive charging application, the losses associated with the transformer makes it a critical component. In order to calculate the transformer losses, its parameters such as AC resistance, leakage inductance and self capacitance of the high voltage (HV...

  19. Voltage-Controlled Square/Triangular Wave Generator with Current Conveyors and Switching Diodes

    Martin Janecek

    2012-12-01

    Full Text Available A novel relaxation oscillator based on integrating the diode-switched currents and Schmitt trigger is presented. It is derived from a known circuit with operational amplifiers where these active elements were replaced by current conveyors. The circuit employs only grounded resistances and capacitance and is suitable for high frequency square and triangular signal generation. Its frequency can be linearly and accurately controlled by voltage that is applied to a high-impedance input. Computer simulation with a model of a manufactured conveyor prototype verifies theoretic assumptions.

  20. Structure-function of proteins interacting with the α1 pore-forming subunit of high-voltage-activated calcium channels

    AlanNeely

    2014-01-01

    Openings of high-voltage-activated calcium channels lead to a transient increase in calcium concentration that in turn activate a plethora of cellular functions, including muscle contraction, secretion and gene transcription. To coordinate all these responses calcium channels form supramolecular assemblies containing effectors and regulatory proteins that couple calcium influx to the downstream signal cascades and to feedback elements. According to the original biochemical characterization of...

  1. Optimization of salt adsorption rate in membrane capacitive deionization.

    Zhao, R; Satpradit, O; Rijnaarts, H H M; Biesheuvel, P M; van der Wal, A

    2013-04-01

    Membrane capacitive deionization (MCDI) is a water desalination technique based on applying a cell voltage between two oppositely placed porous electrodes sandwiching a spacer channel that transports the water to be desalinated. In MCDI, ion-exchange membranes are positioned in front of each porous electrode to prevent co-ions from leaving the electrode region during ion adsorption, thereby enhancing the salt adsorption capacity. MCDI can be operated at constant cell voltage (CV), or at a constant electrical current (CC). In this paper, we present both experimental and theoretical results for desalination capacity and rate in MCDI (both in the CV- and the CC-mode) as function of adsorption/desorption time, salt feed concentration, electrical current, and cell voltage. We demonstrate how by varying each parameter individually, it is possible to systematically optimize the parameter settings of a given system to achieve the highest average salt adsorption rate and water recovery. PMID:23395310

  2. Differences between direct current and alternating current capacitance nonlinearities in high-k dielectrics and their relation to hopping conduction

    Capacitance nonlinearities were studied in atomic layer deposited HfO2 films using two types of signals: a pure ac voltage of large magnitude (ac nonlinearities) and a small ac voltage superimposed to a large dc voltage (dc nonlinearities). In theory, ac and dc nonlinearities should be of the same order of magnitude. However, in practice, ac nonlinearities are found to be an order of magnitude higher than dc nonlinearities. Besides capacitance nonlinearities, hopping conduction is studied using low-frequency impedance measurements and is discussed through the correlated barrier hopping model. The link between hopping and nonlinearity is established. The ac nonlinearities are ascribed to the polarization of isolated defect pairs, while dc nonlinearities are attributed to electrode polarization which originates from defect percolation paths. Both the ac and dc capacitance nonlinearities display an exponential variation with voltage, which results from field-induced lowering of the hopping barrier energy

  3. Estimation of mean exocytic vesicle capacitance in mouse adrenal chromaffin cells

    Moser, Tobias; Neher, Erwin

    1997-01-01

    Whole-cell membrane capacitance measurements are frequently used to monitor neuronal and nonneuronal secretory activity. However, unless individual fusion events can be resolved, the type of the fusing vesicles cannot be identified in these experiments. Here we apply statistical analysis of trial-to-trial variations between depolarization-induced capacitance increases of mouse adrenal chromaffin cells and obtain estimates for the capacitance contribution of individual exocytic vesicles betwee...

  4. Shale gas produced water treatment using innovative microbial capacitive desalination cell

    Stoll, Zachary A. [New Mexico State University, Las Cruces, NM 88003 (United States); Forrestal, Casey [University of Colorado Boulder, Boulder, CO 80309 (United States); Ren, Zhiyong Jason, E-mail: jason.ren@colorado.edu [University of Colorado Boulder, Boulder, CO 80309 (United States); Xu, Pei, E-mail: wxpei@hotmail.com [New Mexico State University, Las Cruces, NM 88003 (United States)

    2015-02-11

    Highlights: • Actual shale gas produced water was treated with no external energy input. • Biodegradation of organics generated stable voltages for desalination. • On average, 36 mg TDS per g activated carbon was removed in 1 h. • A maximum organic removal rate of 6.4 mg DOC per hour was achieved in the reactor. - Abstract: The rapid development of unconventional oil and gas production has generated large amounts of wastewater for disposal, raising significant environmental and public health concerns. Treatment and beneficial use of produced water presents many challenges due to its high concentrations of petroleum hydrocarbons and salinity. The objectives of this study were to investigate the feasibility of treating actual shale gas produced water using a bioelectrochemical system integrated with capacitive deionization—a microbial capacitive desalination cell (MCDC). Microbial degradation of organic compounds in the anode generated an electric potential that drove the desalination of produced water. Sorption and biodegradation resulted in a combined organic removal rate of 6.4 mg dissolved organic carbon per hour in the reactor, and the MCDC removed 36 mg salt per gram of carbon electrode per hour from produced water. This study is a proof-of-concept that the MCDC can be used to combine organic degradation with desalination of contaminated water without external energy input.

  5. Shale gas produced water treatment using innovative microbial capacitive desalination cell

    Highlights: • Actual shale gas produced water was treated with no external energy input. • Biodegradation of organics generated stable voltages for desalination. • On average, 36 mg TDS per g activated carbon was removed in 1 h. • A maximum organic removal rate of 6.4 mg DOC per hour was achieved in the reactor. - Abstract: The rapid development of unconventional oil and gas production has generated large amounts of wastewater for disposal, raising significant environmental and public health concerns. Treatment and beneficial use of produced water presents many challenges due to its high concentrations of petroleum hydrocarbons and salinity. The objectives of this study were to investigate the feasibility of treating actual shale gas produced water using a bioelectrochemical system integrated with capacitive deionization—a microbial capacitive desalination cell (MCDC). Microbial degradation of organic compounds in the anode generated an electric potential that drove the desalination of produced water. Sorption and biodegradation resulted in a combined organic removal rate of 6.4 mg dissolved organic carbon per hour in the reactor, and the MCDC removed 36 mg salt per gram of carbon electrode per hour from produced water. This study is a proof-of-concept that the MCDC can be used to combine organic degradation with desalination of contaminated water without external energy input

  6. Capacitance Regression Modelling Analysis on Latex from Selected Rubber Tree Clones

    Rosli, A. D.; Hashim, H.; Khairuzzaman, N. A.; Mohd Sampian, A. F.; Baharudin, R.; Abdullah, N. E.; Sulaiman, M. S.; Kamaru'zzaman, M.

    2015-11-01

    This paper investigates the capacitance regression modelling performance of latex for various rubber tree clones, namely clone 2002, 2008, 2014 and 3001. Conventionally, the rubber tree clones identification are based on observation towards tree features such as shape of leaf, trunk, branching habit and pattern of seeds texture. The former method requires expert persons and very time-consuming. Currently, there is no sensing device based on electrical properties that can be employed to measure different clones from latex samples. Hence, with a hypothesis that the dielectric constant of each clone varies, this paper discusses the development of a capacitance sensor via Capacitance Comparison Bridge (known as capacitance sensor) to measure an output voltage of different latex samples. The proposed sensor is initially tested with 30ml of latex sample prior to gradually addition of dilution water. The output voltage and capacitance obtained from the test are recorded and analyzed using Simple Linear Regression (SLR) model. This work outcome infers that latex clone of 2002 has produced the highest and reliable linear regression line with determination coefficient of 91.24%. In addition, the study also found that the capacitive elements in latex samples deteriorate if it is diluted with higher volume of water.

  7. Identification of both GABAA receptors and voltage-activated Na+ channels as molecular targets of anticonvulsant α-asarone

    Ze-JunWang

    2014-03-01

    Full Text Available Alpha (α-asarone, a major effective component isolated from the Chinese medicinal herb Acorus tatarinowii, is clinically used as medication for treating epilepsy, cough, bronchitis, and asthma. In the present study, we demonstrated that α-asarone targets central nervous system GABAA receptor as well as voltage-gated Na+ channels. Using whole-cell patch-clamp recording, -asarone inhibited spontaneous firing of output neurons, mitral cells (MCs, in mouse olfactory bulb brain slice preparations and hyperpolarized the membrane potential of MCs. The inhibitory effect of α-asarone persisted in the presence of ionotropic glutamate receptor blockers but was eliminated after adding a GABAA receptor blocker, suggesting that GABAA receptors mediated the inhibition of MCs by α-asarone. This hypothesis was supported by the finding that α-asarone evoked an outward current, but did not influence inhibitory postsynaptic currents (IPSCs. In addition to inhibiting spontaneous firing, α-asarone also inhibited the Nav1.2 channel, a dominant rat brain Na+ channel subtype. The effects of α-asarone on a defined Nav1.2 were characterized using transfected cells that stably expressed the Nav1.2 channel isoform. α-Asarone displayed strong tonic inhibition of Nav1.2 currents in a concentration- and membrane potential-dependent fashion. α-Asarone reduced channel availability in steady-state inactivation protocols by enhancing or stabilizing Na+ channel inactivation. Both Na+ channel blockade and activation of GABAA receptors provide a possible mechanism for the known anti-epileptic effects of α-asarone. It also suggests that α-asarone could benefit patients with cough possibly through inhibiting a Na+ channel subtype to inhibit peripheral and/or central sensitization of cough reflexes.

  8. Improving capacitance/damping ratio in a capacitive MEMS transducer

    Damping forces play an important role in capacitive MEMS (microelectromechanical systems) behavior, and typical damper design (parallel-plates) cannot address the design conflict between increase in electrical capacitance and damping reduction. Squeeze-film damping in in-plane parallel-plate MEMS is discussed here and a novel damper geometry for gap-varying parallel-plates is introduced and used to increase the capacitance/damping ratio. The new geometry is compared with a typical parallel-plate design for an silicon-on-insulator process (25 µm thick) and experimental data shows an approximate 25% to 50% reduction for the damping coefficient in structures with 500 µm long dampers (for a gap variation between 0.75 and 3.75 µm), in agreement with computational fluid dynamics simulations, without significantly affecting the capacitance value (∼4% reduction). Preliminary simulations to study the role of the different geometric parameters involved in the improved geometry are also performed and reveal that the channel width is the most critical value for effective damping reduction. (paper)

  9. Compensation of the detector capacitance presented to charge-sensitive preamplifiers using the Miller effect

    Kwon, Inyong; Kang, Taehoon; Wells, Byron T.; D'Aries, Lawrence J.; Hammig, Mark D.

    2015-06-01

    This paper describes an integrated circuit design for a modified charge-sensitive amplifier (CSA) that compensates for the effect of capacitance presented by nuclear radiation detectors and other sensors. For applications that require large area semiconductor detectors or for those semiconductor sensors derived from high permittivity materials such as PbSe, the detector capacitance can degrade the system gain and bandwidth of a front-end preamplifier, resulting in extended rise times and attenuated output voltage signals during pulse formation. In order to suppress the effect of sensor capacitance, we applied a bootstrap technique into a traditional CSA. The technique exploits the Miller effect by reducing the effective voltage difference between the two sides of a radiation detector which minimizes the capacitance presented to the differential common-source amplifier. This new configuration is successfully designed to produce effective gain even at high detector capacitance. The entire circuit, including a core CSA with feedback components and a bootstrap amplifier, are implemented in a 0.18 μm CMOS process with a 3.3 V supply voltage.

  10. Capacitance recovery analysis and modelling of supercapacitors during cycling ageing tests

    Highlights: • The performances degradation of supercapacitors during power cycling ageing tests have been quantified. • The performances recovery phenomena of supercapacitors is highlighted and modelled. • The impact of the rest conditions (temperature and cut-off voltage) on the recovery behaviour is quantified. • An accurate ageing model able to predict the performances degradation of supercapacitors in power cycling is proposed. - Abstract: During accelerated ageing tests of supercapacitors (SC), a decay in their performance is reflected by a decrease in capacitance and an increase in equivalent series resistance ESR. In power cycling, when electric solicitations of the SC are interrupted for the purposes of real use or characterisation, performance recovery is observed, mainly in terms of an increase in capacitance. This phenomenon is due to a redistribution of electrical charges, balancing of impurities inside the porous carbon electrodes, and the cell’s return to thermodynamically steady-state conditions. A repetitive long rest period during cycling appears to slow down the ageing process, and to reduce the decay in performance. The impacts on capacitance recovery during rest time, of both cut-off voltage and temperature, are studied. A nonlinear analytical expression is used to predict the capacitance decay for several durations and test interruption periodicities; this is also used to model the capacitance during rest time, taking the cut-off voltage, rest time and temperature into account

  11. Composition change and capacitance properties of ruthenium oxide thin film

    刘泓; 甘卫平; 刘仲武; 郑峰

    2015-01-01

    RuO2·nH2O film was deposited on tantalum foils by electrodeposition and heat treatment using RuCl3·3H2O as precursor. Surface morphology, composition change and cyclic voltammetry from precursor to amorphous and crystalline RuO2·nH2O films were studied by X-ray diffractometer, Fourier transformation infrared spectrometer, differential thermal analyzer, scanning electron microscope and electrochemical analyzer, respectively. The results show that the precursor was transformed gradually from amorphous to crystalline phase with temperature. When heat treated at 300 °C for 2 h, RuO2·nH2O electrode surface gains mass of 2.5 mg/cm2 with specific capacitance of 782 F/g. Besides, it is found that the specific capacitance of the film decreased by roughly 20%with voltage scan rate increasing from 5 to 250 mV/s.

  12. Accurate quasi static capacitance for abrupt homojunction under forward and reverse polarization

    D Boukredimi; H Allouche

    2013-04-01

    In this work, we present a new approach to derive the capacitance–voltage characteristic for an abrupt homojunction with uniform doping (A in -region and D in -region) under forward and reverse polarization. Under thermal equilibrium conditions, we show that it is possible to obtain analytically the exact capacitance–voltage characteristic without any simulation for the symmetric case (A = D). We also propose a model of the total capacitance under forward and reverse polarization for the asymmetric case (A ≠ D).

  13. Electron Trapping and Interface State Generation in PMOSFET’s: Results from Gate Capacitance

    Ling, C. H.

    1993-10-01

    Significant generation of hot-carrier induced donor and acceptor interface states in PMOSFET’s is observed for the first time from gate-to-drain capacitance Cgd*s. Plotting the change \\varDelta Cgd*s against gate bias reveals two peaks, attributed to donor and acceptor states. A voltage on the drain displaces the donor peak by approximately the amount of the applied voltage, but the acceptor peak shifts by a fixed amount.

  14. Flow pattern identification based on a single-wire capacitance probe

    To identify flow patterns in horizontal gas-liquid flows,a single-wire capacitance probe was used for voltage output for the first time. Regardless of the measurement accuracy of water layer height, the statistic parameters of the voltage-time traces were compared within the same sampling time of 5 s under different flow patterns, including maximum, minimum, range, and average. The results show that most of flow patterns were accurately identified except for some transition lines. (authors)

  15. Capacitive tool standoff sensor for dismantlement tasks

    A capacitive sensing technology has been applied to develop a Standoff Sensor System for control of robotically deployed tools utilized in Decontamination and Dismantlement (D and D) activities. The system combines four individual sensor elements to provide non-contact, multiple degree-of-freedom control of tools at distances up to five inches from a surface. The Standoff Sensor has been successfully integrated to a metal cutting router and a pyrometer, and utilized for real-time control of each of these tools. Experiments demonstrate that the system can locate stationary surfaces with a repeatability of 0.034 millimeters

  16. Capacitive tool standoff sensor for dismantlement tasks

    Schmitt, D.J.; Weber, T.M. [Sandia National Labs., Albuquerque, NM (United States); Liu, J.C. [Univ. of Illinois, Urbana, IL (United States)

    1996-12-31

    A capacitive sensing technology has been applied to develop a Standoff Sensor System for control of robotically deployed tools utilized in Decontamination and Dismantlement (D and D) activities. The system combines four individual sensor elements to provide non-contact, multiple degree-of-freedom control of tools at distances up to five inches from a surface. The Standoff Sensor has been successfully integrated to a metal cutting router and a pyrometer, and utilized for real-time control of each of these tools. Experiments demonstrate that the system can locate stationary surfaces with a repeatability of 0.034 millimeters.

  17. Structure-function of proteins interacting with the alpha1 pore-forming subunit of high voltage-activated calcium channel

    Alan eNeely

    2014-06-01

    Full Text Available Openings of high-voltage-activated calcium channels lead to a transient increase in calcium concentration that in turn activate a plethora of cellular functions, including muscle contraction, secretion and gene transcription. To coordinate all these responses calcium channels form supramolecular assemblies containing effectors and regulatory proteins that couple calcium influx to the downstream signal cascades and to feedback elements. According to the original biochemical characterization of skeletal muscle Dihydropyridine receptors, high-voltage-activated calcium channels are multi-subunit protein complexes consisting of a pore-forming subunit (α1 associated with four additional polypeptide chains β, α2, δ and γ, often referred to as accessory subunits. Twenty-five years after the first purification of a high-voltage calcium channel, the concept of a flexible stoichiometry to expand the repertoire of mechanisms that regulate calcium channel influx has emerged. Several other proteins have been identified that associate directly with the α1-subunit, including calmodulin and multiple members of the small and large GTPase family. Some of these proteins only interact with a subset of α1-subunits and during specific stages of biogenesis. More strikingly, most of the α1-subunit interacting proteins, such as the β-subunit and small GTPases, regulate both gating and trafficking through a variety of mechanisms. Modulation of channel activity covers almost all biophysical properties of the channel. Likewise, regulation of the number of channels in the plasma membrane is performed by altering the release of the α1-subunit from the endoplasmic reticulum, by reducing its degradation or enhancing its recycling back to the cell surface. In this review, we discuss the structural basis, interplay and functional role of selected proteins that interact with the central pore-forming subunit of high-voltage-activated calcium channels.

  18. Resilient architecture design for voltage variation

    Reddi, Vijay Janapa

    2013-01-01

    Shrinking feature size and diminishing supply voltage are making circuits sensitive to supply voltage fluctuations within the microprocessor, caused by normal workload activity changes. If left unattended, voltage fluctuations can lead to timing violations or even transistor lifetime issues that degrade processor robustness. Mechanisms that learn to tolerate, avoid, and eliminate voltage fluctuations based on program and microarchitectural events can help steer the processor clear of danger, thus enabling tighter voltage margins that improve performance or lower power consumption. We describe

  19. High voltage distributed amplifier

    Willems, D.; Bahl, I.; Wirsing, K.

    1991-12-01

    A high-voltage distributed amplifier implemented in GaAs MMIC technology has demonstrated good circuit performance over at least two octave bandwidth. This technique allows for very broadband amplifier operation with good efficiency in satellite, active-aperture radar, and battery-powered systems. Also, by increasing the number of FETs, the amplifier can be designed to match different voltage rails. The circuit does require a small amount of additional chip size over conventional distributed amplifiers but does not require power dividers or additional matching networks. This circuit configuration should find great use in broadband power amplifier design.

  20. Energy-aware Supply Voltage and Body Biasing Voltage Scheduling Algorithm for Real-time Distributed Systems

    SUYajuan; WEIShaojun

    2005-01-01

    Technique of energy minimization by combining Dynamic voltage scheduling (DVS) and Adaptive body biasing voltage (ABB) method for distributed realtime system at design level is proposed. First, a simplified energy optimizing model is illustrated where the supply voltage or body biasing voltage is kept as constant according to each separated frequency region, thus calculation of exceeding equation is avoided. Divergence of simplified and analytic model within 5% indicates the accuracy of this model. Based on it, the proposed approach named LEVVS (Low energy supply voltage and body biasing voltage scheduling algorithm) explores space of minimizing energy consumption by finding optimal trade-off between dynamic and static energy. The corresponding optimal supply voltage and body biasing voltage are determined by an iterative method in which the supply voltage and body biasing voltage of tasks are adjusted according to the value of energy latency differential coefficient of each task and slack time distribution of the system. Experiments show that using LEVVS approach, 51% more average energy reduction can be obtained than employing DVS method alone. Furthermore the effects of switch capacitance and global slack on the energy saving efficiency of LEVVS are investigated. The smaller the global slack or average switch capacitance is, the more the energy saving of LEVVS compared with DVS is.

  1. A Capacitive Humidity Sensor Based on Multi-Wall Carbon Nanotubes (MWCNTs

    Zhen-Gang Zhao

    2009-09-01

    Full Text Available A new type of capacitive humidity sensor is introduced in this paper. The sensor consists of two plate electrodes coated with MWCNT films and four pieces of isolating medium at the four corners of the sensor. According to capillary condensation, the capacitance signal of the sensor is sensitive to relative humidity (RH, which could be transformed to voltage signal by a capacitance to voltage converter circuit. The sensor is tested using different saturated saline solutions at the ambient temperature of 25 °C, which yielded approximately 11% to 97% RH, respectively. The function of the MWCNT films, the effect of electrode distance, the temperature character and the repeatability of the sensor are discussed in this paper.

  2. Capacitance variation in electrostatic energy harvester with conductive droplet moving on electret film

    This work addresses numerical finite element calculations on a droplet-based electrostatic energy harvester to reveal additional characteristics that supplement previous test results. Assumptions of 2D electrode and static droplet profile have been applied to make the simulation achievable based on the real prototype. We investigate the consequences of a uniform space charge distribution in the film. Capacitance variation and open-circuit voltage of the simulation model have been determined and display respectively maximum and minimum magnitudes when the droplet is in the middle of finger gap. The sharp variation of capacitance, during which the droplet moves from the gap centre to the finger centre, can explain the narrow peaks of output voltage seen in experiments. Additionally, the influence of droplet size on the capacitance variation is also investigated

  3. Water desalination via capacitive deionization

    Suss, M.E.; Porada, S.; Sun, X.; Biesheuvel, P.M.; Yoon, J.; Presser, V.

    2015-01-01

    Capacitive deionization (CDI) is an emerging technology for the facile removal of charged ionic species from aqueous solutions, and is currently being widely explored for water desalination applications. The technology is based on ion electrosorption at the surface of a pair of electrically charg

  4. Water and chemical savings in cooling towers by using membrane capacitive deionization

    Limpt, van B.; Wal, van der A.

    2014-01-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a voltage difference between two oppositely placed porous carbon electrodes. In front of each electrode, an ion exchange membrane is positioned, and between them, a spacer is situated, which transports the w

  5. Time varying voltage combustion control and diagnostics sensor

    Chorpening, Benjamin T.; Thornton, Jimmy D.; Huckaby, E. David; Fincham, William

    2011-04-19

    A time-varying voltage is applied to an electrode, or a pair of electrodes, of a sensor installed in a fuel nozzle disposed adjacent the combustion zone of a continuous combustion system, such as of the gas turbine engine type. The time-varying voltage induces a time-varying current in the flame which is measured and used to determine flame capacitance using AC electrical circuit analysis. Flame capacitance is used to accurately determine the position of the flame from the sensor and the fuel/air ratio. The fuel and/or air flow rate (s) is/are then adjusted to provide reduced flame instability problems such as flashback, combustion dynamics and lean blowout, as well as reduced emissions. The time-varying voltage may be an alternating voltage and the time-varying current may be an alternating current.

  6. Survey of Induced Voltage and Current Phenomena in GIS Substation

    Seyed Mohammad Hassan Hosseini

    2014-03-01

    Full Text Available Induced capacitive voltage and current in high voltage GIS substation is one of the most significant phenomena that may have made some problems in this substation operation. At this study the various equipment of 420 KV Karoon4 substations such as powerhouses, input and output lines, bus-bar and bus-duct have simulated by applying EMTP-RV software. Then with the different condition of single-phase and three-phase faults on the lines in critical conditions, capacitive induction voltage and current by parallel capacitor with circuit breaker is surveyed. The results show the value of this induced current and voltage and that this critical conditions the breakers and dis-connector switches must be able to interrupt this value of current.

  7. The Low-Voltage Electromagnetic Compaction of Powder Materials

    WU Yan-Chun; HUANG Shang-yu; CHANG Zhi-hua; TIAN Zhen-wu

    2002-01-01

    The low-voltage-electromagnetic forming was applied to powder compaction. A series of experiments was performed to compact aluminum, copper and tin powders in an indirect working way. Having compacted high-density powder parts successfully, the authors analyzed the effects of voltage, capacitance, friction, compaction times, powder size and other factors on the densities of compacted specimens. The experimental results show that lower voltage but larger capacitance are beneficial to increasing the density and homogeneity of the compacted specimens, if the loading velocity and discharging energy are suitable. The higher the voltage, the greater the percentage of energy consumed by friction. If the equipment energy is limited, the iterative compaction is an efficient way to manufacture homogeneous and high-density powder parts.

  8. Voltage-dependent Ca2+ channels, not ryanodine receptors, activate Ca2+-dependent BK potassium channels in human retinal pigment epithelial cells

    Wimmers, Sönke; Halsband, Claire; Seyler, Sebastian; Milenkovic, Vladimir; Strauß, Olaf

    2008-01-01

    Purpose In different tissues the activation of large conductance Ca2+-activated (BK) potassium channels has been shown to be coupled to voltage-gated Ca2+ channels as well as ryanodine receptors. As activation of BK channels leads to hyperpolarization of the cell, these channels provide a negative feedback mechanism for Ca2+-induced functions. Many cellular functions of the retinal pigment epithelium (RPE) are coupled to changes in [Ca2+]i. The aim of this study was to identify which Ca2+-ent...

  9. Cytoplasmic cAMP-sensing domain of hyperpolarization-activated cation (HCN) channels uses two structurally distinct mechanisms to regulate voltage gating

    Wicks, Nadine L.; Wong, Tammy; Sun, Jinyi; Madden, Zarina; Young, Edgar C.

    2010-01-01

    Voltage gating of hyperpolarization-activated cation (HCN) channels is potentiated by direct binding of cAMP to a cytoplasmic cAMP-sensing domain (CSD). When unliganded, the CSD inhibits hyperpolarization-dependent opening of the HCN channel gate; cAMP binding relieves this autoinhibition so that opening becomes more favorable thermodynamically. This autoinhibition-relief mechanism is conserved with that of several other cyclic nucleotide receptors using the same ligand-binding fold. Besides ...

  10. Molecular and functional differences in voltage-activated sodium currents between GABA projection neurons and dopamine neurons in the substantia nigra

    Ding, Shengyuan; Wei, Wei; Zhou, Fu-Ming

    2011-01-01

    GABA projection neurons (GABA neurons) in the substantia nigra pars reticulata (SNr) and dopamine projection neurons (DA neurons) in substantia nigra pars compacta (SNc) have strikingly different firing properties. SNc DA neurons fire low-frequency, long-duration spikes, whereas SNr GABA neurons fire high-frequency, short-duration spikes. Since voltage-activated sodium (NaV) channels are critical to spike generation, the different firing properties raise the possibility that, compared with DA...

  11. Functional Apical Large Conductance, Ca2+-activated, and Voltage-dependent K+ Channels Are Required for Maintenance of Airway Surface Liquid Volume*

    Manzanares, Dahis; Gonzalez, Carlos; Ivonnet, Pedro; Chen, Ren-Shiang; Valencia-Gattas, Monica; Gregory E. Conner; Larsson, H. Peter; Salathe, Matthias

    2011-01-01

    Large conductance, Ca2+-activated, and voltage-dependent K+ (BK) channels control a variety of physiological processes in nervous, muscular, and renal epithelial tissues. In bronchial airway epithelia, extracellular ATP-mediated, apical increases in intracellular Ca2+ are important signals for ion movement through the apical membrane and regulation of water secretion. Although other, mainly basolaterally expressed K+ channels are recognized as modulators of ion transport in airway epithelial ...

  12. The research of package for CdZnTe detector based on the capacitive Frisch grid structure

    Qin, Kai-feng; Wang, Lin-jun; Min, Jia-hua; Teng, Jianyong; Shi, Zhu-bin; Zhou, Chen-ying; Zhang, Ji-jun; Huang, Jian; Xia, Yiben

    2009-07-01

    In this paper, the design and fabrication of a capacitive Frisch grid structure for CdZnTe (CZT) detector were investigated. The aging tests were first used to investigate the degradation of the mechanical and electrical characteristics of the CdZnTe detector based on the capacitive frisch grid structure. The effects of the degradation on the performance of CdZnTe detectors were investigated by scanning acoustic microscopy (SAM) test, current-voltage test, and multichannel pulse-height spectrum analysis. In particular, a passivation layer obtained by a two-step passivation processing, combined with a Teflon tape, was used as an insulated layer of the capacitive Frisch grid detector, improving its stability effectively at high voltages. However, further improvements in material and device fabrication (including insulated layer) were required to realize the potential of CZT detectors with the capacitive Frisch grid structure.

  13. Effects of stray capacitance to ground in bipolar water impedance measurements based on capacitive electrodes

    Pallàs Areny, Ramon; Aliau Bonet, Carles

    2015-01-01

    Liquid impedance measurements based on capacitive (or contactless) electrodes Overcome electrode polarization problems but are affected by stray capacitance from the material being measured to ground, the same as measurements with direct-contact electrodes. This study shows that the effects of that capacitance depend on the impedance being measured and for bipolar impedance measurements they increase when the ratio between that stray capacitance and lectrode capacitance increases.

  14. Analytical carrier density and quantum capacitance for graphene

    Wang, Lingfei; Wang, Wei; Xu, Guangwei; Ji, Zhuoyu; Lu, Nianduan, E-mail: lunianduan@ime.ac.cn; Li, Ling, E-mail: lingli@ime.ac.cn; Liu, Ming [Key Laboratory of Microelectronics Devices and Integrated Technology, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China); Laboratory of Nanofabrication and Novel Device Integration, Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029 (China)

    2016-01-04

    A disorder based analytical carrier density for graphene is presented here. The carrier density, a basic property of all semiconductors, is obtained based on exponential distribution describing the potential fluctuations induced by impurities and shows good agreement with numerical results. The quantum capacitance is subsequently derived from the carrier density, with a good agreement with experimental measurements. A method for extracting the gate coupling function is also proposed, which relates the internal surface potential with the external applied gate voltage. The essential properties of graphene device physics, such as the temperature, material disorder, and surface potential dependences, are captured in these analytical equations.

  15. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials.

    Lani, Shane W; Wasequr Rashid, M; Hasler, Jennifer; Sabra, Karim G; Levent Degertekin, F

    2014-02-01

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally efficient, mutual radiation impedance based approach to model a finite-size array and realistic parameters of variation. The simulations are verified, and tunability is demonstrated by experiments on a linear CMUT array operating in 2-12 MHz range. PMID:24753623

  16. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally efficient, mutual radiation impedance based approach to model a finite-size array and realistic parameters of variation. The simulations are verified, and tunability is demonstrated by experiments on a linear CMUT array operating in 2-12 MHz range

  17. Capacitive micromachined ultrasonic transducer arrays as tunable acoustic metamaterials

    Lani, Shane W., E-mail: shane.w.lani@gmail.com, E-mail: karim.sabra@me.gatech.edu, E-mail: levent.degertekin@me.gatech.edu; Sabra, Karim G. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); Wasequr Rashid, M.; Hasler, Jennifer [School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States); Levent Degertekin, F. [George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, 801Ferst Drive, Georgia 30332-0405 (United States); School of Electrical and Computer Engineering, Georgia Institute of Technology, Van Leer Electrical Engineering Building, 777 Atlantic Drive NW, Atlanta, Georgia 30332-0250 (United States)

    2014-02-03

    Capacitive Micromachined Ultrasonic Transducers (CMUTs) operating in immersion support dispersive evanescent waves due to the subwavelength periodic structure of electrostatically actuated membranes in the array. Evanescent wave characteristics also depend on the membrane resonance which is modified by the externally applied bias voltage, offering a mechanism to tune the CMUT array as an acoustic metamaterial. The dispersion and tunability characteristics are examined using a computationally efficient, mutual radiation impedance based approach to model a finite-size array and realistic parameters of variation. The simulations are verified, and tunability is demonstrated by experiments on a linear CMUT array operating in 2-12 MHz range.

  18. Modelling of Chirality-Dependent Current-Voltage Characteristics of Carbon-Nanotube Field-Effect Transistors

    ZHAO Xu; WANG Yan; YU Zhi-Ping

    2006-01-01

    @@ Current-voltage characteristics of ballistic carbon-nanotube field-effect transistors are characterized with an it-erative simulation program. The influence of carbon-nanotube chirality and diameter on the output current is considered. An analytical current-voltage expression under the quantum capacitance limit and low-voltage application is derived. Our simulation results are compared with actual measurement data.

  19. Long-Term Spatiotemporal Reconfiguration of Neuronal Activity Revealed by Voltage-Sensitive Dye Imaging in the Cerebellar Granular Layer

    Gandolfi, Daniela; Mapelli, Jonathan; D’Angelo, Egidio

    2015-01-01

    Understanding the spatiotemporal organization of long-term synaptic plasticity in neuronal networks demands techniques capable of monitoring changes in synaptic responsiveness over extended multineuronal structures. Among these techniques, voltage-sensitive dye imaging (VSD imaging) is of particular interest due to its good spatial resolution. However, improvements of the technique are needed in order to overcome limits imposed by its low signal-to-noise ratio. Here, we show that VSD imaging ...

  20. VFT PHASE VOLTAGE MEASUREMENT IN THREE-PHASE ENCLOSED GIS

    邹建华; 岳子丁; 李洋

    2002-01-01

    The measuring of VFT phase voltage in three-phase enclosed GIS is more complex and difficult than in single-phase ones. There are 3 capacitive sensors in the measuring system, the outputs of which are with a linear relation to the three phase voltages. This linear relation is presented with a factorial matrix. Because each capacitive sensor is coupled with the electric field of three phases (A, B, and C), the electric coupling coefficients are introduced. In order to determine the matrix of electric coupling coefficients, the numerical calculation method can be used. From the discussion on two types of three-phase enclosed GIS bus, i.e. standard arrangement and biased arrangement, the dominant electric coupling coefficients are named, which can be simply and approximately calculated by an analytic expression. Finally, as an example, the waveforms of VFT phase voltage generated on a three-phase enclosed GIS bus model are displayed. When a capacitive sensor is located at the 'shortest point' of phase A (or B, or C), the VFT phase voltage VA (or VB, or VC) can almost be measured by that capacitive sensor alone.

  1. [Impact of sperm capacitation on various populations of human spermatozoa].

    Villanueva Díaz, C; Suárez Juárez, M; Díaz, M A; Ayala Ruiz, A

    1989-02-01

    With the purpose of evaluating the impact of spermatic capacitation on different spermatozooa populations, 49 samples of semen, before and after in vitro spermatic capacitation with Ham F-10 medium, were studied; motility of cells was evaluated according to WHO criteria. There was diminution of percentage of immobile cells, 27.8 to 20.0, as well as increase in population of cells with more mobility, 28.6% to 39.1%. Both difference were statistically significant (p = less than 0.05 and p = less than 0.005, respectively). These data suggest that spermatic capacitacion activates "in cascade" all groups of gametes. PMID:2486981

  2. The non-selective voltage-activated cation channel in the human red blood cell membrane: reconciliation between two conflicting reports and further characterisation

    Kaestner, Lars; Christophersen, Palle; Bernhardt, Ingolf; Bennekou, P.

    Erythrocyte; Patch-clamp; Non-specific; cation channel; Voltage dependence; Acetylcholin receptor......Erythrocyte; Patch-clamp; Non-specific; cation channel; Voltage dependence; Acetylcholin receptor...

  3. Water desalination via capacitive deionization

    Suss, M. E.; Porada, S.; Sun, X.; Biesheuvel, P. M.; Yoon, J.; Presser, V.

    2015-01-01

    Capacitive deionization (CDI) is an emerging technology for the facile removal of charged ionic species from aqueous solutions, and is currently being widely explored for water desalination applications. The technology is based on ion electrosorption at the surface of a pair of electrically charged electrodes, commonly composed of highly porous carbon materials. The CDI community has grown exponentially over the past decade, driving tremendous advances via new cell architectures and system de...

  4. Capacitive de-ionization electrode

    Daily, III, William D.

    2013-03-19

    An electrode "cell" for use in a capacitive deionization (CDI) reactor consists of the electrode support structure, a non-reactive conductive material, the electrode accompaniment or substrate and a flow through screen/separator. These "layers" are repeated and the electrodes are sealed together with gaskets between two end plates to create stacked sets of alternating anode and cathode electrodes in the CDI reactor.

  5. Capacitively-Heated Fluidized Bed

    Mchale, E. J.

    1982-01-01

    Fluidized-bed chamber in which particles in bed are capacitively heated produces high yields of polycrystalline silicon for semiconductor devices. Deposition of unrecoverable silicon on chamber wall is reduced, and amount of recoverable silicon depositing on seed particles in bed is increased. Particles also have a size and density suitable for direct handling without consolidation, unlike silicon dust produced in heated-wall chambers.

  6. Energy recovery in membrane capacitive deionization.

    Długołęcki, Piotr; van der Wal, Albert

    2013-05-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a cell voltage between two oppositely placed porous carbon electrodes. In front of each electrode, an ion-exchange membrane is positioned, and between them, a spacer is situated, which transports the water to be desalinated. In this work, we demonstrate for the first time that up to 83% of the energy used for charging the electrodes during desalination can be recovered in the regeneration step. This can be achieved by charging and discharging the electrodes in a controlled manner by using constant current conditions. By implementing energy recovery as an integral part of the MCDI operation, the overall energy consumption can be as low as 0.26 (kW·h)/m(3) of produced water to reduce the salinity by 10 mM, which means that MCDI is more energy efficient for treatment of brackish water than reverse osmosis. Nevertheless, the measured energy consumption is much higher than the thermodynamically calculated values for desalinating the water, and therefore, a further improvement in thermodynamic efficiency will be needed in the future. PMID:23477563

  7. Acoustic lens for capacitive micromachined ultrasonic transducers

    Capacitive micromachined ultrasonic transducers (CMUTs) have great potential to compete with traditional piezoelectric transducers in therapeutic ultrasound applications. In this paper we have designed, fabricated and developed an acoustic lens formed on the CMUT to mechanically focus ultrasound. The acoustic lens was designed based on the paraxial theory and made of silicone rubber for acoustic impedance matching and encapsulation. The CMUT was fabricated based on the local oxidation of silicon (LOCOS) and fusion-bonding. The fabricated CMUT was verified to behave like an electromechanical resonator in air and exhibited wideband response with a center frequency of 2.2 MHz in immersion. The fabrication for the acoustic lens contained two consecutive mold castings and directly formed on the surface of the CMUT. Applied with ac burst input voltages at the center frequency, the CMUT with the acoustic lens generated an output pressure of 1.89 MPa (peak-to-peak) at the focal point with an effective focal gain of 3.43 in immersion. Compared to the same CMUT without a lens, the CMUT with the acoustic lens demonstrated the ability to successfully focus ultrasound and provided a viable solution to the miniaturization of the multi-modality forward-looking endoscopes without electrical focusing. (paper)

  8. Anomalous capacitance of quantum well double-barrier diodes

    Boric, Olga; Tolmunen, Timo J.; Kollberg, Erik; Frerking, Margaret A.

    1992-01-01

    The S-parameters of several different quantum well double barrier diodes have been measured. A technique has been developed for measuring whisker contacted diodes with an HP 8510B automatic network analyzer. Special coaxial mounts using K-connectors were designed to enable measurements up to 20 GHz. The voltage-dependent conductance and capacitance were derived from the measured reflection coefficient of each device. The C/V characteristics were observed to exhibit an anomalous increase at voltages corresponding to the negative differential resistance region (NDR). These are the first reported S-parameter measurements in the negative differential resistance region of quantum well double barrier diodes. A theory is presented that explains, in part, the observed results.

  9. Direct measurement of specific membrane capacitance in neurons.

    Gentet, L J; Stuart, G J; Clements, J D

    2000-07-01

    The specific membrane capacitance (C(m)) of a neuron influences synaptic efficacy and determines the speed with which electrical signals propagate along dendrites and unmyelinated axons. The value of this important parameter remains controversial. In this study, C(m) was estimated for the somatic membrane of cortical pyramidal neurons, spinal cord neurons, and hippocampal neurons. A nucleated patch was pulled and a voltage-clamp step was applied. The exponential decay of the capacitative charging current was analyzed to give the total membrane capacitance, which was then divided by the observed surface area of the patch. C(m) was 0.9 microF/cm(2) for each class of neuron. To test the possibility that membrane proteins may alter C(m), embryonic kidney cells (HEK-293) were studied before and after transfection with a plasmid coding for glycine receptor/channels. The value of C(m) was indistinguishable in untransfected cells and in transfected cells expressing a high level of glycine channels, indicating that differences in transmembrane protein content do not significantly affect C(m). Thus, to a first approximation, C(m) may be treated as a "biological constant" across many classes of neuron. PMID:10866957

  10. Design, construction, and test of a passive optical prototype high voltage instrument transformer

    Christensen, Lars Hofmann

    1995-01-01

    This paper describes an optical voltage transformer (OVT) for a 132-130 kV system based on the Pockels effect in a Bi4Ge3O12 crystal. Different from the majority of OVTs reported, this construction does not use any capacitive voltage division. To accomplish this, it was necessary to redesign the...

  11. A capacitive bioelectrode for recording electrophysiological signals

    In this paper we describe a gel-free sensor with on-board electrode design, which capacitive couples to the skin to detect the electrical activity in the body. The integrated sensor is manufactured on a standard printed circuit board within 2.2 cm diameter enclosure that can operate through fabric or other insulation. The electrode includes amplification (60db gain) and passive band pass filtering (0.5 to 100 Hz). Active shielding surrounding the sensor plate is used to reduce noise pickup. The input referred noise, measured over the electrode bandwidth is 4 μV rms at 0.2 mm sensor distance, and 16 μV rms at 1.2 mm distance trough two cotton cloths. The bioelectrodes were coupled to the scalp trough hair for EEG signals (with 80 db gain), and coupled to the chest through clothing for ECG signals. The recorded signals show well performance of the designed bielectrode. (Author)

  12. Design of an integrated thermoelectric generator power converter for ultra-low power and low voltage body energy harvesters aimed at ExG active electrodes

    Ataei, Milad; Robert, Christian; Boegli, Alexis; Farine, Pierre-André

    2015-10-01

    This paper describes a detailed design procedure for an efficient thermal body energy harvesting integrated power converter. The procedure is based on the examination of power loss and power transfer in a converter for a self-powered medical device. The efficiency limit for the system is derived and the converter is optimized for the worst case scenario. All optimum system parameters are calculated respecting the transducer constraints and the application form factor. Circuit blocks including pulse generators are implemented based on the system specifications and optimized converter working frequency. At this working condition, it has been demonstrated that the wide area capacitor of the voltage doubler, which provides high voltage switch gating, can be eliminated at the expense of wider switches. With this method, measurements show that 54% efficiency is achieved for just a 20 mV transducer output voltage and 30% of the chip area is saved. The entire electronic board can fit in one EEG or ECG electrode, and the electronic system can convert the electrode to an active electrode.

  13. Design of an integrated thermoelectric generator power converter for ultra-low power and low voltage body energy harvesters aimed at ExG active electrodes

    This paper describes a detailed design procedure for an efficient thermal body energy harvesting integrated power converter. The procedure is based on the examination of power loss and power transfer in a converter for a self-powered medical device. The efficiency limit for the system is derived and the converter is optimized for the worst case scenario. All optimum system parameters are calculated respecting the transducer constraints and the application form factor. Circuit blocks including pulse generators are implemented based on the system specifications and optimized converter working frequency. At this working condition, it has been demonstrated that the wide area capacitor of the voltage doubler, which provides high voltage switch gating, can be eliminated at the expense of wider switches. With this method, measurements show that 54% efficiency is achieved for just a 20 mV transducer output voltage and 30% of the chip area is saved. The entire electronic board can fit in one EEG or ECG electrode, and the electronic system can convert the electrode to an active electrode. (paper)

  14. Capacitive VAr requirements for wind driven self-excited induction generators

    This paper presents the capacitive VAr requirements of a three phase pole changing self-excited induction generator and a single phase self-excited induction generator, used as isolated power sources by a constant speed or a variable speed prime mover, to obtain the desired voltage regulation at various values of load and speed. Different performance criteria such as constant terminal voltage or constant air gap flux have been considered. The developed mathematical model using nodal analysis based on graph theory is quite general in nature and can be used for any combination of the unknown variables such as magnetizing reactance (X M) and frequency (F) or capacitive reactance (X C) and frequency (F) or capacitive reactance (X C) and speed (υ). The proposed model completely avoids the tedious and erroneous manual work of segregating the real and imaginary components of the complex impedance of the machine for deriving the specific model for each operating modes. Moreover, any element, like the core loss component, can be included or excluded from the model if required. Next, to obtain the capacitive VAr requirements of a three phase pole changing self-excited induction generator and a single phase self-excited induction generator, a fuzzy logic approach is used for the first time to find the unknown variables using the above model. The results are presented in a normalized form so that they are valid for a wide range of machines and would be useful for the design of voltage regulators for such generators

  15. The Design of Phase-Locked-Loop Circuit for Precision Capacitance Micrometer

    Li Shujie

    2016-01-01

    Full Text Available High precision non-contact micrometer is normally divided into three categories: inductance micrometer, capacitance micrometer and optical interferometer micrometer. The capacitance micrometer is widely used because it has high performance to price ratio. With the improvement of automation level, precision of capacitance micrometer is required higher and higher. Generally, capacitance micrometer consists of the capacitance sensor, capacitance/voltage conversion circuit, and modulation and demodulation circuits. However, due to the existing of resistors, capacitors and other components in the circuit, the phase shift of the carrier signal and the modulated signal might occur. In this case, the specific value of phase shift cannot be determined. Therefore, error caused by the phase shift cannot be eliminated. This will reduce the accuracy of micrometer. In this design, in order to eliminate the impact of the phase shift, the phase-locked-loop (PLL circuit is employed. Through the experiment, the function of tracking the input signal phase and frequency is achieved by the phase-locked-loop circuit. This signal processing method can also be applied to tuber electrical resistance tomography system and other precision measurement circuit.

  16. Conductive polymer foam surface improves the performance of a capacitive EEG electrode.

    Baek, Hyun Jae; Lee, Hong Ji; Lim, Yong Gyu; Park, Kwang Suk

    2012-12-01

    In this paper, a new conductive polymer foam-surfaced electrode was proposed for use as a capacitive EEG electrode for nonintrusive EEG measurements in out-of-hospital environments. The current capacitive electrode has a rigid surface that produces an undefined contact area due to its stiffness, which renders it unable to conform to head curvature and locally isolates hairs between the electrode surface and scalp skin, making EEG measurement through hair difficult. In order to overcome this issue, a conductive polymer foam was applied to the capacitive electrode surface to provide a cushioning effect. This enabled EEG measurement through hair without any conductive contact with bare scalp skin. Experimental results showed that the new electrode provided lower electrode-skin impedance and higher voltage gains, signal-to-noise ratios, signal-to-error ratios, and correlation coefficients between EEGs measured by capacitive and conventional resistive methods compared to a conventional capacitive electrode. In addition, the new electrode could measure EEG signals, while the conventional capacitive electrode could not. We expect that the new electrode presented here can be easily installed in a hat or helmet to create a nonintrusive wearable EEG apparatus that does not make users look strange for real-world EEG applications. PMID:22961261

  17. Hold-Up Time Analysis of a DC-Link Module With a Series Voltage Compensator

    Wang, Huai; Liu, Wenchao; Chung, Henry

    2012-01-01

    A dc-link module composed of dc-link capacitors and a series voltage compensator has been proposed. It has been verified that the module can reduce the dc-link capacitance to 10–20% while achieving a very low voltage ripple across its output terminals. This paper investigates the required dc......-link capacitance when a certain period of hold-up time is considered. Trade-off design conditions are presented and the hold-up time is compared with the solution without the series voltage compensator. The analysis is crucial to power converters connected to critical loads when hold-up time is required. The...

  18. Reversible, voltage-activated formation of biomimetic membranes between triblock copolymer-coated aqueous droplets in good solvents.

    Tamaddoni, Nima; Taylor, Graham; Hepburn, Trevor; Michael Kilbey, S; Sarles, Stephen A

    2016-06-21

    Biomimetic membranes assembled from block copolymers attract considerable interest because they exhibit greater stability and longetivity compared to lipid bilayers, and some enable the reconstitution of functional transmembrane biomolecules. Yet to-date, block copolymer membranes have not been achieved using the droplet interface bilayer (DIB) method, which uniquely allows assembling single- and multi-membrane networks between water droplets in oil. Herein, we investigate the formation of poly(ethylene oxide)-b-poly(dimethyl siloxane)-b-poly(ethylene oxide) triblock copolymer-stabilized interfaces (CSIs) between polymer-coated aqueous droplets in solutions comprising combinations of decane, hexadecane and AR20 silicone oil. We demonstrate that triblock-coated droplets do not spontaneously adhere in these oils because all are thermodynamically good solvents for the hydrophobic PDMS middle block. However, thinned planar membranes are reversibly formed at the interface between droplets upon the application of a sufficient transmembrane voltage, which removes excess solvent from between droplets through electrocompression. At applied voltages above the threshold required to initiate membrane thinning, electrowetting causes the area of the CSI between droplets to increase while thickness remains constant; the CSI electrowetting response is similar to that encountered with lipid-based DIBs. In combination, these results reveal that stable membranes can be assembled in a manner that is completely reversible when an external pressure is used to overcome a barrier to adhesion caused by solvent-chain interactions, and they demonstrate new capability for connecting and disconnecting aqueous droplets via polymer-stabilized membranes. PMID:27174295

  19. KOH改性活性炭涂层电极的电容去离子性能研究%Research on the capacitive deionization performance of activated carbon-coated eIectrodes modified with KOH

    蒋绍阶; 马丹丹; 盛贵尚; 蒋世龙; 陈莽

    2015-01-01

    The surface modification has been made to the commercial activated carbon powder with KOH. The sur-face structure of activated carbon,before and after the modification are analyzed with BET. The capacitive deioniza-tion adsorption device is established with activated carbon-coated electrodes. The deionization effect of the modified electrode is researched. The research shows that after being modified with KOH ,the specific surface area of activa-ted carbons is increased from 519.25 m2/g to 975.07 m2/g;it means that its increase in percentage is 87.78%. The percentage of medium-size pore volume is 48.28%higher than the total pore volume. The pore structure and pore-size distribution are more advantageous for Na+and Cl-to get through,raising the electrode adsorption rate.%用KOH对市售的粉末活性炭进行表面改性。采用BET分析改性前后活性炭的表面结构,并采用活性炭涂层电极构建电容去离子吸附装置,研究改性后电极的去离子效果。研究表明:经过KOH改性后,活性炭的比表面积从519.25 m2/g增加到975.07 m2/g,提高了87.78%,中孔孔容占总孔孔容的百分比提高了48.28%,改性后活性炭的孔隙结构和孔径的分布更有利于溶液中的Na+和Cl-通过,提高了电极的吸附速率。

  20. The tarantula toxin jingzhaotoxin-XI (κ-theraphotoxin-Cj1a) regulates the activation and inactivation of the voltage-gated sodium channel Nav1.5.

    Tang, Cheng; Zhou, Xi; Huang, Yin; Zhang, Yunxiao; Hu, Zhaotun; Wang, Meichi; Chen, Ping; Liu, Zhonghua; Liang, Songping

    2014-12-15

    Specific peptide toxins interact with voltage-gated sodium channels by regulating the activation or inactivation of targeted channels. However, few toxins possessing dual effects have been identified. In the present study, we showed that jingzhaotoxin-XI/κ-theraphotoxin-Cj1a (JZTX-XI), a 34-residue peptide from the venom of the Chinese spider Chilobrachys jingzhao, inhibits the sodium conductance (IC50 = 124 ± 26 nM) and slows the fast inactivation (EC50 = 1.18 ± 0.2 μM) of Nav1.5 expressed in Chinese hamster ovary (CHO-K1) cells. JZTX-XI significantly shifted the activation to more depolarized voltages and decreased the deactivation of Nav1.5 currents upon extreme depolarization, but only slightly affected voltage-dependence of steady-state inactivation. In addition, JZTX-XI caused an approximately five-fold decrease in the rate of recovery from inactivation and an approximately 1.9-fold reduction in the closed-state inactivation rate. Our data suggest that JZTX-XI integrates the functions of site 3 toxins (α-scorpion toxins) with site 4 toxins (β-scorpion and spider toxins) by targeting multiple sites on Nav1.5. The unique properties displayed by JZTX-XI in its inhibitory activity on Nav1.5 suggest that its mechanism of action is distinct from those of site 3 and site 4 toxins, making JZTX-XI a useful probe for investigating the gating mechanism of Nav1.5 and toxin-channel interactions. PMID:25240294