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Sample records for voltage ac resistive

  1. Influence of metallic trays on the ac resistance and ampacity of low-voltage cables under non-sinusoidal currents

    Energy Technology Data Exchange (ETDEWEB)

    Demoulias, Charis; Labridis, Dimitris P.; Dokopoulos, Petros; Gouramanis, Kostas [Aristotle University of Thessaloniki, Department of Electrical and Computer Engineering, Thessaloniki (Greece)

    2008-05-15

    This paper investigates the influence of metallic trays on the ac resistance of PVC insulated, low-voltage (0.6/1.0 kV) cables made according to CENELEC standard HD603. The investigation is made with a validated finite element model for the fundamental and higher harmonic frequencies. It is shown that the cable's effective resistance is affected significantly by the relative magnetic permeability and specific conductivity of the tray, while the tray's dimensions do not affect it. The orientation of the cable with respect to the tray also influences the ac resistance of the phase and neutral conductors. An ampacity derating factor is defined and calculated for various cable cross-sections and harmonic loads. The presence of a metallic tray is shown to cause an additional derating of cable's ampacity which is relatively significant at large cable cross-sections. Working examples demonstrate the application of the results in calculating the ampacity of low-voltage cables and in assessing the energy savings that will result from the use of active harmonic filters. (author)

  2. Conventional P-ω/Q-V Droop Control in Highly Resistive Line of Low-Voltage Converter-Based AC Microgrid

    DEFF Research Database (Denmark)

    Hou, Xiaochao; Sun, Yao; Yuan, Wenbin

    2016-01-01

    In low-voltage converter-based alternating current (AC) microgrids with resistive distribution lines, the P-V droop with Q-f boost (VPD/FQB) is the most common method for load sharing. However, it cannot achieve the active power sharing proportionally. To overcome this drawback, the conventional P......-ω/Q-V droop control is adopted in the low-voltage AC microgrid. As a result, the active power sharing among the distributed generators (DGs) is easily obtained without communication. More importantly, this study clears up the previous misunderstanding that conventional P-ω/Q-V droop control is only applicable...... to microgrids with highly inductive lines, and lays a foundation for the application of conventional droop control under different line impedances. Moreover, in order to guarantee the accurate reactive power sharing, a guide for designing Q-V droop gains is given, and virtual resistance is adopted to shape...

  3. Conventional P-ω/Q-V Droop Control in Highly Resistive Line of Low-Voltage Converter-Based AC Microgrid

    Directory of Open Access Journals (Sweden)

    Xiaochao Hou

    2016-11-01

    Full Text Available In low-voltage converter-based alternating current (AC microgrids with resistive distribution lines, the P-V droop with Q-f boost (VPD/FQB is the most common method for load sharing. However, it cannot achieve the active power sharing proportionally. To overcome this drawback, the conventional P-ω/Q-V droop control is adopted in the low-voltage AC microgrid. As a result, the active power sharing among the distributed generators (DGs is easily obtained without communication. More importantly, this study clears up the previous misunderstanding that conventional P-ω/Q-V droop control is only applicable to microgrids with highly inductive lines, and lays a foundation for the application of conventional droop control under different line impedances. Moreover, in order to guarantee the accurate reactive power sharing, a guide for designing Q-V droop gains is given, and virtual resistance is adopted to shape the desired output impedance. Finally, the effects of power sharing and transient response are verified through simulations and experiments in converter-based AC Microgrid.

  4. Cryocooled Josephson standards for AC voltage metrology

    Science.gov (United States)

    Durandetto, P.; Sosso, A.; Monticone, E.; Trinchera, B.; Fretto, M.; Lacquaniti, V.

    2017-05-01

    The Josephson effect is worldwide used as a basis for constant reference voltages in national metrological institutes and in calibration laboratories of industry. Research on Josephson voltage standards is aiming at a fundamental change also in the metrology of the volt for AC and arbitrary waveforms: programmable Josephson voltage standards converting a digital code into a quantum-accurate stepwise waveform are already available in primary laboratories and even more advanced standards for converting sub-nanosecond binary coded pulses into any arbitrary signal with quantum accuracy are now actively developed and tested. A new experimental setup based on a two-stage Gifford-McMahon cryocooler has been developed at INRiM for the operation of AC-Josephson voltage standards. Among its distinct features, the possibility of employing both the aforementioned techniques (programmable and pulsed Josephson voltage standards) is particularly interesting. Quantum-based AC voltage sine waves have been synthesized with both programmable and pulse-driven arrays, although their accuracy is still limited by thermal oscillations due to the cryocooler piston motion.

  5. Modeling of long High Voltage AC Underground

    DEFF Research Database (Denmark)

    Gudmundsdottir, Unnur Stella; Bak, Claus Leth; Wiechowski, W. T.

    2010-01-01

    This paper presents the work and findings of a PhD project focused on accurate high frequency modelling of long High Voltage AC Underground cables. The project is cooperation between Aalborg University and Energinet.dk. The objective of the project is to investigate the accuracy of most up to date...

  6. Unbalanced Voltage Compensation in Low Voltage Residential AC Grids

    DEFF Research Database (Denmark)

    Trintis, Ionut; Douglass, Philip; Munk-Nielsen, Stig

    2016-01-01

    This paper describes the design and test of a control algorithm for active front-end rectifiers that draw power from a residential AC grid to feed heat pump loads. The control algorithm is able to control the phase to neutral or phase to phase RMS voltages at the point of common coupling....... The voltage control was evaluated with either active or reactive independent phase load current control. The control performance in field operation in a residential grid situated in Bornholm, Denmark was investigated for different use cases....

  7. DC injection into low voltage AC networks

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-07-01

    This report summarises the results of a study investigating the impact of levels of injected DC current injections on a low voltage AC distribution network systems in order to recommend acceptable limits of DC from microgeneration. Relevant literature is reviewed, and the impact of DC levels in distribution transformers, transformer modelling, and instrumental transformers are discussed. The impact of DC in residual current devices (RCD) and in domestic electricity watt hour meters is examined along with DC enhanced corrosion, corrosion failure, and the measurement of DC current injection. Sources of DC injection outlined include DC from computer power supplies, network faults, geomagnetic phenomena, lighting circuits/dimmers, and embedded generators.

  8. Strongly nonlinear dynamics of electrolytes in large ac voltages

    DEFF Research Database (Denmark)

    Olesen, Laurits Højgaard; Bazant, Martin Z.; Bruus, Henrik

    2010-01-01

    We study the response of a model microelectrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a symmetric binary electrolyte confined between parallel-plate blocking electrodes...... in the electrolyte near the electrodes and, at very large voltage, the breakdown of the quasiequilibrium structure of the double layers. The former leads to the prediction of “ac capacitive desalination” since there is a time-averaged transfer of salt from the bulk to the double layers, via oscillating diffusion...... nonlinear responses to large ac voltages, such as Faradaic reactions, electro-osmotic instabilities, and induced-charge electrokinetic phenomena....

  9. Ac Synchronous Servo Based On The Armature Voltage Prediction Model

    Science.gov (United States)

    Hoshino, Akihiro; Kuromaru, Hiroshi; Kobayashi, Shinichi

    1987-10-01

    A new control method of the AC synchro-nous servo-system (Brushless DC servo-system) is discussed. The new system is based on the armature voltage prediction model. Without a resolver-digital-conver-ter nor a tachometer-generator, the resolver provides following three signals to the system immediately, they are the current command, the induced voltage, and the rotor speed. The new method realizes a simple hardware configuration. Experimental results show a good performance of the system.

  10. Moderately nonlinear diffuse-charge dynamics under an ac voltage

    Science.gov (United States)

    Stout, Robert F.; Khair, Aditya S.

    2015-09-01

    The response of a symmetric binary electrolyte between two parallel, blocking electrodes to a moderate amplitude ac voltage is quantified. The diffuse charge dynamics are modeled via the Poisson-Nernst-Planck equations for a dilute solution of point-like ions. The solution to these equations is expressed as a Fourier series with a voltage perturbation expansion for arbitrary Debye layer thickness and ac frequency. Here, the perturbation expansion in voltage proceeds in powers of Vo/(kBT /e ) , where Vo is the amplitude of the driving voltage and kBT /e is the thermal voltage with kB as Boltzmann's constant, T as the temperature, and e as the fundamental charge. We show that the response of the electrolyte remains essentially linear in voltage amplitude at frequencies greater than the RC frequency of Debye layer charging, D /λDL , where D is the ion diffusivity, λD is the Debye layer thickness, and L is half the cell width. In contrast, nonlinear response is predicted at frequencies below the RC frequency. We find that the ion densities exhibit symmetric deviations from the (uniform) equilibrium density at even orders of the voltage amplitude. This leads to the voltage dependence of the current in the external circuit arising from the odd orders of voltage. For instance, the first nonlinear contribution to the current is O (Vo3) which contains the expected third harmonic but also a component oscillating at the applied frequency. We use this to compute a generalized impedance for moderate voltages, the first nonlinear contribution to which is quadratic in Vo. This contribution predicts a decrease in the imaginary part of the impedance at low frequency, which is due to the increase in Debye layer capacitance with increasing Vo. In contrast, the real part of the impedance increases at low frequency, due to adsorption of neutral salt from the bulk to the Debye layer.

  11. Impacts on Power Factor of AC Voltage Controllers Under Non-Sinusoidal Conditions

    Directory of Open Access Journals (Sweden)

    Mukhtiar Ahmed Mahar

    2012-04-01

    Full Text Available AC-AC conversion is obtained with the help of Cyclo-converters, DC Link converters and AC Voltage Controllers. AC voltage controllers are also referred to as voltage regulators. Main issue concerned to these converters is that they generate harmonics due to periodic variable structure system. The generated harmonics create disturbances and degrade the performance of converter. The power factor of supply side is affected due to these harmonics. This paper focuses on source side power factor of ac voltage controllers under nonsinusoidal conditions. In order to observe the power factor, measurement tool of power factor and simulation model of ac voltage controller is also developed in MATLAB software.

  12. Strongly nonlinear dynamics of electrolytes in large ac voltages

    CERN Document Server

    Olesen, Laurits H; Bruus, Henrik

    2009-01-01

    We study the response of a model micro-electrochemical cell to a large ac voltage of frequency comparable to the inverse cell relaxation time. To bring out the basic physics, we consider the simplest possible model of a symmetric binary electrolyte confined between parallel-plate blocking electrodes, ignoring any transverse instability or fluid flow. We analyze the resulting one-dimensional problem by matched asymptotic expansions in the limit of thin double layers and extend previous work into the strongly nonlinear regime, which is characterized by two novel features - significant salt depletion in the electrolyte near the electrodes and, at very large voltage, the breakdown of the quasi-equilibrium structure of the double layers. The former leads to the prediction of "ac capacitive desalination", since there is a time-averaged transfer of salt from the bulk to the double layers, via oscillating diffusion layers. The latter is associated with transient diffusion limitation, which drives the formation and co...

  13. System and method for determining stator winding resistance in an AC motor using motor drives

    Science.gov (United States)

    Lu, Bin; Habetler, Thomas G; Zhang, Pinjia

    2013-02-26

    A system and method for determining the stator winding resistance of AC motors is provided. The system includes an AC motor drive having an input connectable to an AC source and an output connectable to an input terminal of an AC motor, a pulse width modulation (PWM) converter having switches therein to control current flow and terminal voltages in the AC motor, and a control system connected to the PWM converter. The control system generates a command signal to cause the PWM converter to control an output of the AC motor drive corresponding to an input to the AC motor, selectively generates a modified command signal to cause the PWM converter to inject a DC signal into the output of the AC motor drive, and determines a stator winding resistance of the AC motor based on the DC signal of at least one of the voltage and current.

  14. Experimental investigation of SDBD plasma actuator driven by AC high voltage with a superimposed positive pulse bias voltage

    Science.gov (United States)

    Qi, Xiao-Hua; Yan, Hui-Jie; Yang, Liang; Hua, Yue; Ren, Chun-Sheng

    2017-08-01

    In this work, a driven voltage consisting of AC high voltage with a superimposed positive pulse bias voltage ("AC+ Positive pulse bias" voltage) is adopted to study the performance of a surface dielectric barrier discharge plasma actuator under atmospheric conditions. To compare the performance of the actuator driven by single-AC voltage and "AC+ Positive pulse bias" voltage, the actuator-induced thrust force and power consumption are measured as a function of the applied AC voltage, and the measured results indicate that the thrust force can be promoted significantly after superimposing the positive pulse bias voltage. The physical mechanism behind the thrust force changes is analyzed by measuring the optical properties, electrical characteristics, and surface potential distribution. Experimental results indicate that the glow-like discharge in the AC voltage half-cycle, next to the cycle where a bias voltage pulse has been applied, is enhanced after applying the positive pulse bias voltage, and this perhaps is the main reason for the thrust force increase. Moreover, surface potential measurement results reveal that the spatial electric field formed by the surface charge accumulation after positive pulse discharge can significantly affect the applied external electric field, and this perhaps can be responsible for the experimental phenomenon that the decrease of thrust force is delayed by pulse bias voltage action after the filament discharge occurs in the glow-like discharge region. The schlieren images further verify that the actuator-induced airflow velocity increases with the positive pulse voltage.

  15. Prediction of Pollution Flashover Voltage Based on Leakage Current Under AC Operating Voltage

    Institute of Scientific and Technical Information of China (English)

    MEI Hongwei; WANG Liming; GUAN Zhicheng; MAO Yingke

    2012-01-01

    This paper presented a model to predict the AC flashover voltage of contaminated suspension insulators.The prediction method is based on the maximum leakage current under AC operating voltage.Three kinds of widely used suspension insulators were tested in various contamination states such as pollution layers with different equivalent salt deposit density(ESDD),different composition of the conductive components,different non-soluble deposit density(NSDD) and different pollution distribution states to simulate the contamination states in nature.The effective ESDD was proposed and calculated.Influences of contamination states to maximum leakage current and flashover voltage were studied.Then,the relationships between flashover voltage and leakage current in these states were presented.Finally,considering the difference of insulator profiles,a new parameter is defined and a model to estimate the flashover voltage based on this parameter is developed.The model could be used in all kinds of suspension insulators in different contamination states and was validated by the test results.

  16. HIGH VOLTAGE SMALL – SIZED ALTERNATIVE CURRENT RESISTIVE DIVIDERS FROM MICROWIRE

    Directory of Open Access Journals (Sweden)

    Berzan V.P.

    2011-04-01

    Full Text Available The paper discusses the design parameters and characteristics of the new product, the resistive voltage divider produced from microwire for measuring high-voltage alternating current. Resistive dividers are designed for use in AC circuits and power-frequency electric traction network traffic. Dividers have smaller mass-dimensional size compared with the measuring voltage transformers and higher accuracy class 0.2 at a fixed frequency.

  17. A Communication-Less Distributed Voltage Control Strategy for a Multi-Bus AC Islanded Microgrid

    DEFF Research Database (Denmark)

    Wang, Yanbo; Tan, Yongdong; Chen, Zhe

    2014-01-01

    This paper presents a communication-less distributed voltage control strategy for a multi-bus AC islanded microgrid. First, a Kalman Filter-based network voltage estimator is proposed to obtain voltage responses without communication links in the presence of load disturbances. Then, a voltage opt...

  18. System and method for determining stator winding resistance in an AC motor

    Science.gov (United States)

    Lu, Bin; Habetler, Thomas G.; Zhang, Pinjia; Theisen, Peter J.

    2011-05-31

    A system and method for determining stator winding resistance in an AC motor is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of an AC motor. The circuit includes at least one contactor and at least one switch to control current flow and terminal voltages in the AC motor. The system also includes a controller connected to the circuit and configured to modify a switching time of the at least one switch to create a DC component in an output of the system corresponding to an input to the AC motor and determine a stator winding resistance of the AC motor based on the injected DC component of the voltage and current.

  19. Regular structures in 5CB liquid crystals under the joint action of ac and dc voltages

    Science.gov (United States)

    Aguirre, Luis E.; Anoardo, Esteban; Éber, Nándor; Buka, Ágnes

    2012-04-01

    A nematic liquid crystal with high, positive dielectric anisotropy (5CB) has been studied under the influence of the combined action of a dc and an ac electric field. Broad frequency, voltage, and cell thickness ranges were considered. Pattern morphologies were identified; the thresholds and critical wave numbers were measured and analyzed as a function of frequency, dc-to-ac voltage ratio, and thickness. The current-voltage characteristics were simultaneously detected.

  20. Performance Analysis of Phase Controlled Unidirectional and Bidirectional AC Voltage Controllers

    Directory of Open Access Journals (Sweden)

    Abdul Sattar Larik

    2011-01-01

    Full Text Available AC voltage controllers are used to vary the output ac voltage from a fixed ac input source. They are also commonly called ac voltage regulators or ac choppers. The output voltage is either controlled by PAC (Phase Angle Control method or on-off control method. Due to various advantages of ac voltage controllers, such as high efficiency, simplicity, low cost and ability to control large amount of power they efficiently control the speed of ac motors, light dimming and industrial heating, etc. These converters are variable structure systems and generate harmonics during the operation which will affect the power quality when connected to system network. During the last couple of years, a number of new semiconductor devices and various power electronic converters has been introduced. Accordingly the subject of harmonics and its problems are of great concern to power industry and customers. In this research work, initially the simulation models of single phase unidirectional and bidirectional ac voltage controllers were developed by using MATLAB software. The harmonics of these models are investigated by simulation. In the end, the harmonics were also analyzed experimentally. The simulated as well as experimental results are presented.

  1. Performance of Three-Arm Ac Automatic Voltage Regulator

    Directory of Open Access Journals (Sweden)

    T. Papinaidu

    2014-04-01

    Full Text Available In this paper the design and simulation of automatic voltage regulator (AVR is proposed. The AVR provides voltage buck and boost capability to eliminate power problems created by under voltage or over voltage fluctuations. It also protects against minor and severe spikes and surges that comprise over 80% of power problems. Over heating of components due to voltage swell is also avoided by using AVR. The switching losses are also reduced as only one arm among three arms is maintained at higher power frequencies depending on mode of operation. Moreover, there is no need to use large capacitor as a result the overall size of converter is also reduced. Hence, the output voltage of the AVR can be maintained at the specified voltage. Hence, the AVR is cost can be reduced, and the efficiency of the power convertor can be extended.

  2. A Study on Power Quality Improvement in PWM Controlled AC Voltage Controller

    Directory of Open Access Journals (Sweden)

    Ahmet ALTINTAŞ

    2009-04-01

    Full Text Available A lot of topologies of pulse-width modulated (PWM-AC controllers for single-phase and three-phase systems are proposed up to date. PWM-AC controllers have important advantages compared with the phase-controlled AC controllers using thyristors and triacs. The PWM-AC controller has sinusoidal current waveforms, smaller THD values, better power factor, faster dynamics, and smaller input/output filter. This article presents a novel control technique for application to PWM-AC controllers with ability of generating fewer harmonics. In the proposed control method, both the traditional AC voltage controllers and the PWM-AC controllers are combined; and smaller THD values are obtained. Thus, the harmonic pollution in the power system will be reduced; and consequently, the power quality will be increased. For this purpose, computer simulations are performed in order to investigate the proposed controller performance. The obtained results are compared with the conventional PWM-AC controller.

  3. Voltage-sharing Characteristics of Porcelain Insulators for 750 kV AC Substation%Voltage-sharing Characteristics of Porcelain Insulators for 750 kV AC Substation

    Institute of Scientific and Technical Information of China (English)

    ZHANG Shi-ting; PENG Zong-ren; LIAO Jin tao

    2011-01-01

    Considering the complex environment in 750 kV AC substation, porcelain insulators have particular electric field and voltage distribution in comparison with those used in AC transmission line, meanwhile, the investigation of a typical 750 kV AC substation located in Lanzhou with ultraviolet imager (UVI) demonstrated that the corona dis- charge of some insulators is serious due to the improper structure design and installation, so research on porcelain insulators used in substation is needed. The three-dimensional finite element method (FEM) 750 kV AC substation calculation model was established to calculate electric field and voltage distribution of insulators, and the voltage distribution curves along insulators which are classified by type and suspension location were obtained using a novel FEM method which can effectively reduce the calculation amount without losing accuracy, meanwhile, the effect of the grading ring for improving voltage distribution of insulators was studied by adjusting the structure parameters of grad- ing ring. Consequently, an optimization structure of rings was proposed by improving the voltage distribution of insu- lator string and reducing the electric strength of grading ring for the purpose of restricting corona noise, and the on- site observations by UVI showed that the newly manufactured and installed grading ring could obviously avoid the occurrences of corona discharge which validates the optimization design. This paper proposed an effective method combi ning UVI observation and FEM calculation to study voltage-sharing characteristics of porcelain insulators, and the results can provide experiences and references for the design of 750 kV AC substation.

  4. Surface Partial Discharge Characteristics of Oil-paper Insulation Under Combined AC-DC Voltage

    Institute of Scientific and Technical Information of China (English)

    SHA Yanchao; ZHOU Yuanxiang; NIE Dexin; WU Zhirong; DENG Jiangang; LU Licheng

    2013-01-01

    The valve side windings of converter transformers bear AC,DC,impulse,and reversal-polarity voltages during operation,which could result in serious insulation problems of the equipment.By performing experiments with surface discharge model of oil-paper insulation at 80 ℃ under combined AC-DC voltage for 200 h,we studied the spectrums and statistical parameters of partial discharges at different discharge stages.Furthermore,some fingerprint parameters were calculated in order to estimate the development situation of partial discharge,while the characteristic gases dissolved in the transformer oil were measured by gas chromatography.The surface discharges in the experiments were observed using a high speed camera,and a full discharge process could be marked off into four stages as follows.①The elementary stage.When a partial discharge occurs near electrodes,electrical charges are injected into the region near electrodes and causing bubble generation.②Due to their high resistivity and low dielectric constant,the bubbles would bare the major part of the voltage applied to samples.Therefore,discharge happens inside the small bubbles,and it emits a lot of light.③Micmmolecules of gas are produced in discharge,and further ionization in the transformer oil takes place simultaneously when high-energy electrons collide with oil molecules.④The carrier charge moves forward to electrodes driven by the applied electric field,till they neutralize with the charge from electrodes,and hence discharge channels are formed subsequently.

  5. Study of High Voltage AC Underground Cable Systems

    DEFF Research Database (Denmark)

    da Silva, Filipe Miguel Faria; Bak, Claus Leth; Wiechowski, Wojciech T.

    2010-01-01

    High-Voltage cables are starting to be more often used to transmit electric energy at high-voltage levels, introducing in the electric grid phenomena that are uncommon when using Overhead Lines. Under the phenomena worthy of special attention are those related with the cable energisation and deen...

  6. Phase-sensitive detection of both inductive and non-inductive ac voltages in ferromagnetic resonance

    Science.gov (United States)

    Weiler, Mathias; Shaw, Justin M.; Nembach, Hans T.; Schoen, Martin A.; Boone, Carl T.; Silva, Thomas J.

    2014-03-01

    Spin pumping causes significant damping in ultrathin ferromagnetic/normal metal (NM) multilayers via spin-current generation of both dc and ac character in the NM system. While the nonlinear dc component has been investigated in detail by utilization of the inverse spin Hall effect (iSHE) in NMs, much less is known about the linear ac component that is presumably much larger in the small-excitation limit. We measured generated ac voltages in a wide variety of Permalloy/NM multilayers via vector-network-analyzer ferromagnetic resonance. We employ a custom, impedance-matched, broadband microwave coupler that features a ferromagnetic thin film reference resonator to accurately compare ac voltage amplitudes and phases between varieties of multilayers. By use of the fact that inductive and ac iSHE signals are phase-shifted by π/2, we find that inductive signals are major contributors in all investigated samples. It is only by comparison of the phase and amplitude of the recorded ac voltages between multiple samples that we can extract the non-inductive contributions due to spin-currents. Voltages due to the ac iSHE in Permalloy(10nm)/platinum(5nm) bilayers are weaker than inductive signals, in agreement with calculations based upon recent theoretical predictions. M.W. acknowledges financial support by the German Academic Exchange service (DAAD).

  7. Spin Backflow and ac Voltage Generation by Spin Pumping and the Inverse Spin Hall Effect

    Science.gov (United States)

    Jiao, HuJun; Bauer, Gerrit E. W.

    2013-05-01

    The spin current pumped by a precessing ferromagnet into an adjacent normal metal has a constant polarization component parallel to the precession axis and a rotating one normal to the magnetization. The former is now routinely detected as a dc voltage induced by the inverse spin Hall effect (ISHE). Here we compute ac ISHE voltages much larger than the dc signals for various material combinations and discuss optimal conditions to observe the effect. The backflow of spin is shown to be essential to distill parameters from measured ISHE voltages for both dc and ac configurations.

  8. Techniques for detecting proximity to voltage collapse in AC/DC systems

    Energy Technology Data Exchange (ETDEWEB)

    Canizares, Claudio A. [Escuela Politecnica Nacional, Quito (Ecuador); Long, Willis F.; Alvarado, Fernando L.; DeMarco, CChristopher L. [Wisconsin Univ., Madison, WI (United States)

    1992-12-31

    This paper describes three different techniques to detect proximity to voltage collapse (saddle-node bifurcation) in AC/DC systems; namely, direct (point of collapse) methods, continuation methods, and transient energy function methods. These techniques are compared among them, and also against the voltage sensitivity factor method using a 173 bus ac/dc test system. Various operational conditions are considered for this test system, so that transfer capabilities between areas and the effects of HVDC links can be analysed from the point of view of voltage collapse. 24 refs., 7 figs.

  9. A New Transformerless Single-Phase Buck-Boost AC Voltage Regulator

    Directory of Open Access Journals (Sweden)

    YALCIN, F.

    2016-05-01

    Full Text Available Voltage regulation is one of the important goals for electrical sources and consumers. In this paper a new transformerless single-phase AC voltage regulator based on buck-boost converter topology is presented. The regulator circuit has a simple structure using only two bidirectional active switches, one inductor and one capacitor. A closed loop control system is implemented for the proposed regulator operation. A control law depending on the instantaneous values of the regulator's real input and desired output voltage is obtained and supports the PI controller. The control law allows the controller to obtain efficient pulse width modulation (PWM switching duty ratio for the desired output voltage when the input voltage has surges or fluctuations and the output load is changed. An experimental laboratory setup has been implemented for the proposed AC voltage regulator. The obtained results demonstrate that the proposed topology is capable of and efficient for both bucking and boosting the input AC voltage to a high quality output voltage with a low total harmonic distortion (THD for different input voltage and load conditions.

  10. DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

    DEFF Research Database (Denmark)

    Akhter, F.; Macpherson, D.E.; Harrison, G.P.

    2015-01-01

    In this paper, a combinational AC/DC power flow approach is proposed for the solution of the combined AC/DC network. The unified power flow approach is extended to include DC voltage droop control. In the VSC based MTDC grids, DC droop control is regarded as more advantageous in terms...... of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

  11. A Generalised Fault Protection Structure Proposed for Uni-grounded Low-Voltage AC Microgrids

    Science.gov (United States)

    Bui, Duong Minh; Chen, Shi-Lin; Lien, Keng-Yu; Jiang, Jheng-Lun

    2016-04-01

    This paper presents three main configurations of uni-grounded low-voltage AC microgrids. Transient situations of a uni-grounded low-voltage (LV) AC microgrid (MG) are simulated through various fault tests and operation transition tests between grid-connected and islanded modes. Based on transient simulation results, available fault protection methods are proposed for main and back-up protection of a uni-grounded AC microgrid. In addition, concept of a generalised fault protection structure of uni-grounded LVAC MGs is mentioned in the paper. As a result, main contributions of the paper are: (i) definition of different uni-grounded LVAC MG configurations; (ii) analysing transient responses of a uni-grounded LVAC microgrid through line-to-line faults, line-to-ground faults, three-phase faults and a microgrid operation transition test, (iii) proposing available fault protection methods for uni-grounded microgrids, such as: non-directional or directional overcurrent protection, under/over voltage protection, differential current protection, voltage-restrained overcurrent protection, and other fault protection principles not based on phase currents and voltages (e.g. total harmonic distortion detection of currents and voltages, using sequence components of current and voltage, 3I0 or 3V0 components), and (iv) developing a generalised fault protection structure with six individual protection zones to be suitable for different uni-grounded AC MG configurations.

  12. An AMOLED AC-Biased Pixel Design Compensating the Threshold Voltage and I-R Drop

    Directory of Open Access Journals (Sweden)

    Ching-Lin Fan

    2011-01-01

    Full Text Available We propose a novel pixel design and an AC bias driving method for active-matrix organic light-emitting diode (AM-OLED displays using low-temperature polycrystalline silicon thin-film transistors (LTPS-TFTs. The proposed threshold voltage and I-R drop compensation circuit, which comprised three transistors and one capacitor, have been verified to supply uniform output current by simulation work using the Automatic Integrated Circuit Modeling Simulation Program with Integrated Circuit Emphasis (AIM-SPICE simulator. The simulated results demonstrate excellent properties such as low error rate of OLED anode voltage variation (<0.7% and low voltage drop of VDD power line. The proposed pixel circuit effectively enables threshold-voltage-deviation correction of driving TFT and compensates for the voltage drop of VDD power line using AC bias on OLED cathode.

  13. A fiber optic hybrid multifunctional AC voltage sensor

    Energy Technology Data Exchange (ETDEWEB)

    Sokolovsky, A.; Zadvornov, S. [IRE, Moscow (Russian Federation); Ryabko, M. [UFD, Moscow (Russian Federation)

    2008-07-01

    Hybrid sensors have the advantages of both electronic and optical technologies. Their sensing element is based on conventional transducers and the optical fiber is used as a transmission media for the optical signal encoded with information between the local module and the remote module. The power supply for the remote module is usually provided by a built-in photoelectric converter illuminated by the optical radiation going through the same or another optical fiber. Electro-optic hybrid sensors have been widely used because of the electrical isolation provided by optical fiber. In the conventional fiber optic voltage sensor, piezoelectric or electro-optic transducers are implemented. Processing and conditioning measurement information is a complex task in these sensors. Moreover, the considerable drawback of most of these systems is that only one parameter, usually voltage value, is measured. This paper presented a novel fiber optic hybrid sensor for alternating current voltage measurements. This instrument provides the simultaneous measurement of four parameters, notably voltage value, frequency, phase angle and the external temperature. The paper described the measurement technology of the instrument including the remote module and optical powering as well as the unique modulation algorithm. The results and conclusions were also presented. 7 refs., 4 figs.

  14. A New Coordinated Voltage Control Scheme for Offshore AC Grid of HVDC Connected Offshore Wind Power Plants

    DEFF Research Database (Denmark)

    Sakamuri, Jayachandra N.; Cutululis, Nicolaos Antonio; Rather, Zakir Hussain;

    2015-01-01

    This paper proposes a coordinated voltage control scheme (CVCS) which enhances the voltage ride through (VRT) capability of an offshore AC grid comprised of a cluster of offshore wind power plants (WPP) connected through AC cables to the offshore voltage source converter based high voltage DC (VSC-HVDC......) converter station. Due to limited short circuit power contribution from power electronic interfaced variable speed wind generators and with the onshore main grid decoupled by the HVDC link, the offshore AC grid becomes more vulnerable to dynamic voltage events. Therefore, a short circuit fault...... in the offshore AC Grid is likely to have significant implications on the voltage of the offshore AC grid, hence on the power flow to the onshore mainland grid. The proposed CVCS integrates individual local reactive power control of wind turbines and of the HVDC converter with the secondary voltage controller...

  15. Monolithic blue LED series arrays for high-voltage AC operation

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Jin-Ping [Satellite Venture Business Laboratory, University of Tokushima, Tokushima 770-8506 (Japan); Sato, Hisao; Mizobuchi, Takashi; Morioka, Kenji; Kawano, Shunsuke; Muramoto, Yoshihiko; Sato, Daisuke; Sakai, Shiro [Nitride Semiconductor Co. Ltd., Naruto, Tokushima 771-0360 (Japan); Lee, Young-Bae; Ohno, Yasuo [Department of Electrical and Electronic Engineering, University of Tokushima, Tokushima 770-8506 (Japan)

    2002-12-16

    Design and fabrication of monolithic blue LED series arrays that can be operated under high ac voltage are described. Several LEDs, such as 3, 7, and 20, are connected in series and in parallel to meet ac operation. The chip size of a single device is 150 {mu}m x 120 {mu}m and the total size is 1.1 mm x 1 mm for a 40(20+20) LED array. Deep dry etching was performed as device isolation. Two-layer interconnection and air bridge are utilized to connect the devices in an array. The monolithic series array exhibit the expected operation function under dc and ac bias. The output power and forward voltage are almost proportional to LED numbers connected in series. On-wafer measurement shows that the output power is 40 mW for 40(20+20) LED array under ac 72 V. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  16. Cryocooler operation of SNIS Josephson arrays for AC Voltage standards

    Science.gov (United States)

    Sosso, A.; De Leo, N.; Fretto, M.; Monticone, E.; Roncaglione, L.; Rocci, R.; Lacquaniti, V.

    2014-05-01

    Avoiding liquid helium is now a worldwide issue, thus cryocooler operation is becoming mandatory for a wider use of superconductive electronics. Josephson voltage standards hold a peculiar position among superconducting devices, as they are in use in high precision voltage metrology since decades. Higher temperature operation would reduce the refrigerator size and complexity, however, arrays of Josephson junctions made with high temperature superconductors for voltage standard applications are not to date available. The SNIS (Superconductor-Normal metal-Insulator-Superconductor) junction technology developed at INRIM, based on low temperature superconductors, but capable of operation well above liquid helium temperature, is interesting for application to a compact cryocooled standard, allowing to set a compromise between device and refrigerator requirements. In this work, the behavior of SNIS devices cooled with a closed-cycle refrigerator has been investigated, both in DC and under RF irradiation. Issues related to thermal design of the apparatus to solve specific problems not faced with liquid coolants, like reduced cooling power and minimization of thermal gradients for uniform operation of the chip are discussed in detail.

  17. An Annotated Bibliography of High-Voltage Direct-Current Transmission and Flexible AC Transmission (FACTS) Devices, 1991-1993.

    Energy Technology Data Exchange (ETDEWEB)

    Litzenberger, Wayne; Lava, Val

    1994-08-01

    References are contained for HVDC systems, converter stations and components, overhead transmission lines, cable transmission, system design and operations, simulation of high voltage direct current systems, high-voltage direct current installations, and flexible AC transmission system (FACTS).

  18. High Voltage AC underground cable systems for power transmission

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Silva, Filipe Miguel Faria da

    2016-01-01

    This paper is a second of two presenting a review of research results in underground cable transmission obtained by the Department of Energy Technology, Aalborg University ET/AAU and Danish TSO Energinet.dk within the last six years. The main core of the results are obtained by PhD students...... researching electrical engineering topics related to using underground cables for power transmission at EHV level and including the 420 kV level. The research topics were laid down by ET/AAU and Energinet.dk in the DANPAC (DANish Power systems with Ac Cables) research project. The main topics are discussed...

  19. An estimator-based distributed voltage-predictive control strategy for ac islanded microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Chen, Zhe; Wang, Xiongfei

    2015-01-01

    This paper presents an estimator-based voltage predictive control strategy for AC islanded microgrids, which is able to perform voltage control without any communication facilities. The proposed control strategy is composed of a network voltage estimator and a voltage predictive controller for each...... control strategy is analyzed through small signal analysis method, from which the design guideline for the controller parameters is formulated. Furthermore, the robustness of the proposed voltage control strategy is investigated under a series of parameters uncertainties, including the line parameters...... perturbation, load parameters variation, different disturbance locations, LC filters perturbation, output impedances perturbation and DG unit fault. The simulation and experimental results show that the proposed control approach is able to perform offset-free voltage control without any communication links...

  20. An estimator-based distributed voltage-predictive control strategy for AC islanded microgrids

    DEFF Research Database (Denmark)

    Wang, Yanbo; Chen, Zhe; Wang, Xiongfei

    2015-01-01

    This paper presents an estimator-based voltage-predictive control strategy for ac islanded microgrids, which is able to perform voltage control without any communication facilities. The proposed control strategy is composed of a network voltage estimator and a voltage-predictive controller for each...... control strategy is analyzed through small-signal analysis method, from which the design guideline for the controller parameters is formulated. Furthermore, the robustness of the proposed voltage control strategy is investigated under a series of parameters uncertainties, including the line parameters...... perturbation, load parameters variation, different disturbance locations, LC filters perturbation, output impedances perturbation, and DG unit fault. The simulation and experimental results show that the proposed control approach is able to perform offset-free voltage control without any communication links...

  1. Statistical Distributions of Partial Discharges in Oil-paper Insulation Under AC-DC Combined Voltages

    Institute of Scientific and Technical Information of China (English)

    LI Jian; JIANG Tianyan; HE Zhiman; CHENG Changkui; BAO Lianwei

    2012-01-01

    The converter transformer is one of the most critical equipments in high-voltage direct current transmission systems.Valve-side windings have to withstand complex stresses combined of AC,DC,and pulsed voltages.Partial discharges(PDs) can thus easily occur in oil-impregnated paper insulation.The current paper presents the statistical phase-resolved distributions of partial discharges in oil-paper insulation under combined AC and DC voltage stress.First,the voltages in the converter transformer were analyzed.In the experiments,four artificial insulation defect models were designed to generate PD signals under AC-DC combined voltage stress detected by a Rogowski coil sensor.Histograms including the φ-q-n data of these PD signals were created.The variations of φ-q-n data generated by PDs in different insulation defect models were analyzed while increasing the test voltage.Experimental results showed that the PD phase-resolved distributions of different insulation defect models were different from one another.The findings of the current study are useful in further research on the mechanism and pattern recognition of PDs in converter transformers.

  2. High Voltage AC underground cable systems for power transmission

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Silva, Filipe Miguel Faria da

    2016-01-01

    This paper is a first of two presenting a review of research results in underground cable transmission obtained by the Department of Energy Technology, Aalborg University ET/AAU and Danish TSO Energinet.dk within the last 6 years. The main core of the results are obtained by PhD students research......This paper is a first of two presenting a review of research results in underground cable transmission obtained by the Department of Energy Technology, Aalborg University ET/AAU and Danish TSO Energinet.dk within the last 6 years. The main core of the results are obtained by PhD students...... researching electrical engineering topics related to using underground cables for power transmission at EHV level and including the 420 kV level. The research topics were laid down by ET/AAU and Energinet.dk in the DANPAC (DANish Power systems with AC Cables) research project. The main topics are discussed...

  3. AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

    Directory of Open Access Journals (Sweden)

    Rui Li

    2016-12-01

    Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.

  4. Enhanced DC-Link Capacitor Voltage Balancing Control of DC–AC Multilevel Multileg Converters

    DEFF Research Database (Denmark)

    Busquets-Monge, Sergio; Maheshwari, Ram Krishan; Nicolas-Apruzzese, Joan

    2015-01-01

    This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc......-link voltage levels and converter legs (for single-phase and multiphase systems), guaranteeing the capacitor voltage control for any modulation index value and load (from idle mode to full power). The associated control loop small-signal transfer function is presented, from which optimum compensator design...... guidelines are derived. The improvement in control performance is verified through simulation and experiments comparing with a previous balancing control strategy in a four-level three-phase dc–ac conversion system. The satisfactory control performance is also verified through simulation in a four-level five...

  5. Low-Cost Voltage Zero-Crossing Detector for AC-Grid Applications

    Directory of Open Access Journals (Sweden)

    Vorobyov Maxim

    2014-10-01

    Full Text Available Renewable energy sources and energy storage devices are becoming more popular. Some of them like small hydropower turbines, wind turbines and diesel generators produce AC voltage with different frequency and voltage than the main grid. For them power electronics converters are necessary. Power electronics converters presented in industry use two or three level energy conversion, although direct AC to AC converters exist, but one of the main problems is the switch commutation when current or voltage is crossing the zero point. Zero crossing sensors are used to solve this problem. They consist of current or voltage measurement unit and zero crossing detector. Different approaches are used for zero crossing: hardware or software. Hardware approach is simple but it has low precision. Software approach has high precision but it is complicated and expensive. In this paper a simple low cost high precision approach is presented. It takes all advantages from both approaches. While tested with two types of microcontrollers the precision of experimental measurement is 25 μs - 40 μs.

  6. Flow reversal at low voltage and low frequency in a microfabricated ac electrokinetic pump

    DEFF Research Database (Denmark)

    Gregersen, Misha Marie; Olesen, Laurits Højgaard; Brask, Anders

    2007-01-01

    Microfluidic chips have been fabricated in Pyrex glass to study electrokinetic pumping generated by a low-voltage ac bias applied to an in-channel asymmetric metallic electrode array. A measurement procedure has been established and followed carefully resulting in a high degree of reproducibility...... of the measurements over several days. A large coverage fraction of the electrode array in the microfluidic channels has led to an increased sensitivity allowing for pumping measurements at low bias voltages. Depending on the ionic concentration a hitherto unobserved reversal of the pumping direction has been...

  7. Nonlinear control of voltage source converters in AC-DC power system.

    Science.gov (United States)

    Dash, P K; Nayak, N

    2014-07-01

    This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations.

  8. Solid-state fast voltage compensator for pulsed power applications requiring constant AC power consumption

    CERN Document Server

    Magallanes, Francisco Cabaleiro; Viarouge, Philippe; Cros, Jérôme

    2015-01-01

    This paper proposes a novel topological solution for pulsed power converters based on capacitor-discharge topologies, integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This solution has been retained as a possible candidate for the CLIC project under study at CERN, which requires more than a thousand synchronously-operated klystron modulators producing a total pulsed power of almost 40 GW. The proposed Fast Voltage Compensator is integrated in the modulator such that it only has to treat the capacitor charger current and a fraction of the charging voltage, meaning that its dimensioning power and cost are minimized. This topology can be used to improve the AC power quality of any pulsed converters based on capacitor-discharge concept. A prototype has been built and exploited to validate the operating principle and demonstrate the benefits of the proposed solution.

  9. Investigations of surface characterization of silicone rubber due to tracking phenomena under a.c. and d.c. voltages

    Indian Academy of Sciences (India)

    Uma Maheswar Rao; S S M S Abdul Majeed; C Venkataseshaiah; R Sarathi

    2002-11-01

    In the present work, tracking phenomena has been studied with silicone rubber material under the a.c. and d.c. voltages following IEC-587 standards. The surface condition of the tracked zone was analysed using wide angle X-ray diffraction (WAXD) and thermogravimetric differential thermal analysis (TG–DTA) studies. The tracking time was different for a.c. and d.c. voltages.

  10. Absorption Voltages and Insulation Resistance in Ceramic Capacitors with Cracks

    Science.gov (United States)

    Teverovsky, Alexander

    2016-01-01

    Time dependence of absorption voltages (Vabs) in different types of low-voltage X5R and X7R ceramic capacitors was monitored for a maximum duration of hundred hours after polarization. To evaluate the effect of mechanical defects on Vabs, cracks in the dielectric were introduced either mechanically or by thermal shock. The maximum absorption voltage, time to roll-off, and the rate of voltage decrease are shown to depend on the crack-related leakage currents and insulation resistance in the parts. A simple model that is based on the Dow equivalent circuit for capacitors with absorption has been developed to assess the insulation resistance of capacitors. Standard measurements of the insulation resistance, contrary to the measurements based on Vabs, are not sensitive to the presence of mechanical defects and fail to reveal capacitors with cracks. Index Terms: Ceramic capacitor, insulation resistance, dielectric absorption, cracking.

  11. Corona noise model of high-voltage AC transmission lines and engineering applications

    Institute of Scientific and Technical Information of China (English)

    Wu Jiuhui; Di Zelong

    2013-01-01

    In order to predict the levels of corona noise from high-voltage alternating current (AC) transmission lines,the mechanism of corona noise and the corresponding theoretical prediction model are investigated.On the basis of Drude model,the motion of positive and negative ions produced by high-voltage corona is analyzed,and the mechanism of corona noise is discovered.The theoretical prediction model is put forward by using Kirchhoff formula,which is verified by the well agreement between our result and others',considering the case of three-phase single lines.Moreover,the calculation results show that for both single and bundled lines,the sound pressure level of the typical frequency,i.e.twice the power frequency,attenuates slowly and leads to an obviously interferential phenomenon near the transmission lines,but the level of the bundled lines is smaller than that of the single ones under the same transmission voltage.Based on the mechanism of corona noise and the prediction model,it is obvious that bundled lines and/or increased line radius can be adopted to reduce corona noise in the practical engineering applications effectively.This model can also provide a theoretical guidance for the high-volt-age AC transmission line design.

  12. Influence of Load Modes on Voltage Stability of Receiving Network at DC/AC System

    Directory of Open Access Journals (Sweden)

    Mao Chizu

    2016-01-01

    Full Text Available This paper analyses influence of load modes on DC/AC system. Because of widespread use of HVDC, DC/AC system become more complex than before and the present modes used in dispatch and planning departments are not fit in simulation anymore. So it is necessary to find load modes accurately reflecting characteristics of the system. For the sake of the voltage stability, commutation failure, etc. the practical example of the receiving network in a large DC/AC system in China is simulated with BPA, and the influence of Classical Load Mode (CLM and Synthesis load model (SLM on simulation results is studies. Furthermore, some important parameters of SLM are varied respectively among an interval to analyse how they affect the system. According to this practical examples, the result is closely related to load modes and their parameters, and SLM is more conservative but more reasonable than the present modes. The consequences indicate that at critical states, micro variation in parameters may give rise to change in simulation results radically. Thus, correct mode and parameters are important to enhance simulation accuracy of DC/AC system and researches on how they affect the system make senses.

  13. Containment and Consensus-based Distributed Coordination Control for Voltage Bound and Reactive Power Sharing in AC Microgrid

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper offers a highly flexible and reliable control strategy to achieve voltage bounded regulation and accurate reactive power sharing coordinately in AC Micro-Grids. A containment and consensus-based distributed coordination controller is proposed, by which each output voltage magnitude can...

  14. Containment and Consensus-based Distributed Coordination Control for Voltage Bound and Reactive Power Sharing in AC Microgrid

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper offers a highly flexible and reliable control strategy to achieve voltage bounded regulation and accurate reactive power sharing coordinately in AC Micro-Grids. A containment and consensus-based distributed coordination controller is proposed, by which each output voltage magnitude can...

  15. Organolead Halide Perovskites for Low Operating Voltage Multilevel Resistive Switching.

    Science.gov (United States)

    Choi, Jaeho; Park, Sunghak; Lee, Joohee; Hong, Kootak; Kim, Do-Hong; Moon, Cheon Woo; Park, Gyeong Do; Suh, Junmin; Hwang, Jinyeon; Kim, Soo Young; Jung, Hyun Suk; Park, Nam-Gyu; Han, Seungwu; Nam, Ki Tae; Jang, Ho Won

    2016-08-01

    Organolead halide perovskites are used for low-operating-voltage multilevel resistive switching. Ag/CH3 NH3 PbI3 /Pt cells exhibit electroforming-free resistive switching at an electric field of 3.25 × 10(3) V cm(-1) for four distinguishable ON-state resistance levels. The migration of iodine interstitials and vacancies with low activation energies is responsible for the low-electric-field resistive switching via filament formation and annihilation.

  16. Modeling and Design of DC Boost and AC Side Voltage Controllers in Asymmetrical Γ-Source Inverter

    Directory of Open Access Journals (Sweden)

    Seyed Mahyar Mehdizadeh Moghadam

    2014-07-01

    Full Text Available In this paper a control system is proposed to simultaneously control the voltage boost and output voltage of assymetrical Γ-Source Inverters. Dynamic model of the system is used to design the controllers. Voltage boost on assymetrical Γ-Source Inverters is done by voltage control of impedance network capacitor and the regulation of inverter shoot through duty cycle. Since the stability margin of the system is low due to the right half plane zero in its dynamic model, the design of fast control system is impossible therefore a nonlinear feedforward control loop is used to faster the control system performance. Linear control system is used to control the AC-side in synchrony reference frame such that the AC voltage control system regulates the output voltage by means of modulation index regulation. The proposed control system performance is investigated by simulation in MATLAB/Simulink

  17. Voltage Stability Bifurcation Analysis for AC/DC Systems with VSC-HVDC

    Directory of Open Access Journals (Sweden)

    Yanfang Wei

    2013-01-01

    Full Text Available A voltage stability bifurcation analysis approach for modeling AC/DC systems with VSC-HVDC is presented. The steady power model and control modes of VSC-HVDC are briefly presented firstly. Based on the steady model of VSC-HVDC, a new improved sequential iterative power flow algorithm is proposed. Then, by use of continuation power flow algorithm with the new sequential method, the voltage stability bifurcation of the system is discussed. The trace of the P-V curves and the computation of the saddle node bifurcation point of the system can be obtained. At last, the modified IEEE test systems are adopted to illustrate the effectiveness of the proposed method.

  18. A Novel Protection Scheme against Fault Resistance for AC Microgrid

    Directory of Open Access Journals (Sweden)

    Xinrui Liu

    2017-01-01

    Full Text Available The faults characteristics of the lines in AC microgrid are weakened due to the fault resistance, which may refuse protection action. To solve the problems caused by different types of the faults through fault resistance (FTFR, the faults where the fault point resistance is greater than zero in AC microgrid, a novel FTFR protection scheme based on the active power of 0-frame component or d-frame component consumed by fault resistance is proposed in this paper as the backup protection of FTFR. This proposed protection scheme utilizes the active power of 0-frame component or d-frame component consumed by fault resistance to identify internal FTFR and external faults. It performs well in grid-connected mode and islanded mode by adopting self-adaptive threshold and is not affected by the factors such as the fault position and the fault resistance value. The theoretical analysis and various simulations show that this protection scheme can identify and isolate different types of internal FTFR in AC microgrid with high reliability and high sensitivity.

  19. An isolated bridgeless AC-DC PFC converter using a LC resonant voltage doubler rectifier

    Science.gov (United States)

    Lee, Sin-woo; Do, Hyun-Lark

    2016-12-01

    This paper proposed an isolated bridgeless AC-DC power factor correction (PFC) converter using a LC resonant voltage doubler rectifier. The proposed converter is based on isolated conventional single-ended primary inductance converter (SEPIC) PFC converter. The conduction loss of rectification is reduced than a conventional one because the proposed converter is designed to eliminate a full-bridge rectifier at an input stage. Moreover, for zero-current switching (ZCS) operation and low voltage stresses of output diodes, the secondary of the proposed converter is designed as voltage doubler with a LC resonant tank. Additionally, an input-output electrical isolation is provided for safety standard. In conclusion, high power factor is achieved and efficiency is improved. The operational principles, steady-state analysis and design equations of the proposed converter are described in detail. Experimental results from a 60 W prototype at a constant switching frequency 100 kHz are presented to verify the performance of the proposed converter.

  20. Increased deposition of polychlorinated biphenyls (PCBs) under an AC high-voltage power line

    Science.gov (United States)

    Öberg, Tomas; Peltola, Pasi

    2009-12-01

    There is considerable public concern regarding the potential risks to health of electromagnetic fields in general and high-voltage power lines in particular. As epidemiological findings are not supported by a clearly defined mechanism of direct magnetic field interactions with the human body, potential indirect effects are of interest. It has been suggested that an increased exposure to chemical pollutants could occur near high-voltage power lines due to formation and deposition of charged aerosols. The current study reports empirical evidence that seems to support this hypothesis. The deposition of 18 congeners of polychlorinated biphenyls (PCBs) was studied by collecting samples of pine needles under a 400 kV AC power line and at reference sites in the vicinity. Compared to the reference sites, the average deposition of PCB congeners under the power line was almost double. This difference between the two groups of samples was statistically significant. While it is premature to draw any conclusions regarding the human exposure near high-voltage power lines, the issue deserves attention and further investigations.

  1. Voltage source ac-to-dc converters for high-power transmitters

    Science.gov (United States)

    Cormier, R.

    1990-01-01

    This work was done to optimize the design of the components used for the beam power supply, which is a component of the transmitters in the Deep Space Network (DSN). The major findings are: (1) the difference in regulation between a six-pulse and a twelve-pulse converter is at most 7 percent worse for the twelve-pulse converter; (2) the commutation overlap angle of a current source converter equals that of a voltage source converter with continuous line currents; (3) the sources of uncharacteristic harmonics are identified with SPICE simulation; (4) the use of an imperfect phase-shifting transformer for the twelve-pulse converter generates a harmonic at six times the line frequency; and (5) the assumptions usually made in analyzing converters can be relaxed with SPICE simulation. The results demonstrate the suitability of using SPICE simulation to obtain detailed performance predictions of ac-to-dc converters.

  2. Comparative Study of Breakdown Voltage of Mineral, Synthetic and Natural Oils and Based Mineral Oil Mixtures under AC and DC Voltages

    Directory of Open Access Journals (Sweden)

    Abderrahmane Beroual

    2017-04-01

    Full Text Available This paper deals with a comparative study of AC and DC breakdown voltages of based mineral oil mixtures with natural and synthetic esters mainly used in high voltage power transformers. The goal was to analyze the performances of oil mixtures from the dielectric withstand point of view and to predict the behavior of transformers originally filled with mineral oil and re-filled with synthetic or natural ester oils when emptied for maintenance. The study concerns mixtures based on 20%, 50%, and 80% of natural and synthetic ester oils. AC breakdown voltages were measured using a sphere-sphere electrode system according to IEC 60156 specifications; the same specification was adopted for DC measurements since there is no standard specifications for this voltage waveform. A statistical analysis of the mean values, standard deviations, and histograms of breakdown voltage data was carried out. The Normal and Weibull distribution functions were used to analyze the experimental data and the best function that the data followed was used to estimate the breakdown voltage with risk of 1%, 10%, and 50% probability. It was shown that whatever the applied voltage waveforms, ester oils always have a significantly higher breakdown voltage than mineral oil. The addition of only 20% of natural or synthetic ester oil was sufficient to considerably increase the breakdown voltage of mineral oil. The dielectric strength of such a mixture is much higher than that of mineral oil alone and can reach that of ester oils. From the point of view of dielectric strength, the mixtures constitute an option for improving the performance of mineral oil. Thus, re-filling of transformers containing up to 20% mineral oil residues with ester oils, does not present any problem; it is even advantageous when considering only the breakdown voltage. Under AC, the mixtures with natural ester always follow the behavior of vegetable oil alone. With the exception of the 20% mixture of natural

  3. Shunt capacitors for a.c. power systems having a rated voltage above 1000 V - Part 1: General

    CERN Document Server

    International Electrotechnical Commission. Geneva

    2005-01-01

    This part of IEC 60871 is applicable to both capacitor units and capacitor banks intended to be used, particularly, for power-factor correction of a.c. power systems having a rated voltage above 1 000 V and frequencies of 15 Hz to 60 Hz. This part of IEC 60871 also applies to capacitors intended for use in power filter circuits.

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

    Energy Technology Data Exchange (ETDEWEB)

    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)

  5. Power Balance Control in an AC/DC/AC Converter for Regenerative Braking in a Two-Voltage-Level Flywheel-Based Driveline

    Directory of Open Access Journals (Sweden)

    Janaína G. Oliveira

    2011-01-01

    Full Text Available The integration of a flywheel as a power handling can increase the energy storage capacity and reduce the number of battery charge/discharge cycles. Furthermore, the ability of recovering energy of the vehicle during breaking can increase the system efficiency. The flywheel-based all-electric driveline investigated here has its novelty in the use of a double-wound flywheel motor/generator, which divides the system in two different voltage levels, enhancing the efficiency of the electric driveline. The connection of two AC electrical machines (i.e., the flywheel and the wheel motor with different and variable operation frequency is challenging. A power matching control applied to an AC/DC/AC converter has been implemented. The AC/DC/AC converter regenerates the electric power converted during braking to the flywheel machine, used here as power handling device. By controlling the power balance, the same hardware can be used for acceleration and braking, providing the reduction of harmonics and robust response. A simulation of the complete system during braking mode has been performed both in Matlab and Simulink, and their results have been compared. The functionality of the proposed control has been shown and discussed, with full regeneration achieved. A round-trip efficiency (wheel to wheel higher than 80% has been obtained.

  6. Characteristic Analysis of Partial Discharges and Dissolved Gases Generated Cavityin Oil-paper Insulation Under AC-DC Combined Voltages

    Institute of Scientific and Technical Information of China (English)

    HE Zhiman; LI Jian; BAO Lianwei; JIANG Tianyan; WANG Youyuan

    2012-01-01

    Oil-paper insulation is used within most of high voltage direct current(HVDC) converter transformers.Partial discharge(PD) in oil-paper insulation is a major reason for the development of internal faults in HVDC converter transformer,while PDs in oil-paper insulation mainly occur in terms of gas cavity discharges.There are few study results on the development characteristics of partial discharges in oil-paper insulation and dissolved gases in oils of HVDC converter transformers.Based on a gas cavity discharge model of oil-paper insulation,the present study investigates the development characteristics of partial discharges under AC-DC combined voltages and emphatically examines the variation characteristics of dissolved gases in the discharge development process.Experiment and analysis results show that the characteristics of partial discharges and dissolved gases in oils under AC-DC combined voltages are appreciably different with those under AC voltage.These results provide theoretical support for further research on partial discharges and on dissolved gases of other internal insulating defects and are helpful for the fault diagnosis of HVDC converter transformers.

  7. The Space Charge Effect on the Discharge Current in Cross-Linked Polyethylene under High AC Voltages

    Science.gov (United States)

    Kwon, Yoon-Hyeok; Hwangbo, Seung; Lee, June-Ho; Yi, Dong-Young; Han, Min-Koo

    2003-12-01

    The space charge distributions in solid dielectrics have been usually investigated by means of the pulsed electroacoustic (PEA) method. However, most previous studies have been limited to the phenomenological analysis under DC voltages. In our study, the space charge distribution in cross-linked polyethylene (XLPE) has been measured using AC voltages by means of the modified PEA method. Simultaneously, the streamer discharges in an air gap have been measured in order to investigate the relationship between space charge and discharge current, and the relationship has been adapted to the case of dielectric barrier discharge. At high AC voltages, discharge current increases to the critical point, but no further increase is exhibited over the critical voltage and the discharge pattern is resolved by the space charge. This result indicates that the frequency effect and space charge characteristics of dielectric materials are preferred to the voltage effect in the adaptation to dielectric barrier discharge. The results well explain the space charge effect on partial discharge and the dielectric barrier discharge phenomenon.

  8. New resistance mechanism in Helicoverpa armigera threatens transgenic crops expressing Bacillus thuringiensis Cry1Ac toxin.

    Science.gov (United States)

    Gunning, Robin V; Dang, Ho T; Kemp, Fred C; Nicholson, Ian C; Moores, Graham D

    2005-05-01

    In Australia, the cotton bollworm, Helicoverpa armigera, has a long history of resistance to conventional insecticides. Transgenic cotton (expressing the Bacillus thuringiensis toxin Cry1Ac) has been grown for H. armigera control since 1996. It is demonstrated here that a population of Australian H. armigera has developed resistance to Cry1Ac toxin (275-fold). Some 70% of resistant H. armigera larvae were able to survive on Cry1Ac transgenic cotton (Ingard) The resistance phenotype is inherited as an autosomal semidominant trait. Resistance was associated with elevated esterase levels, which cosegregated with resistance. In vitro studies employing surface plasmon resonance technology and other biochemical techniques demonstrated that resistant strain esterase could bind to Cry1Ac protoxin and activated toxin. In vivo studies showed that Cry1Ac-resistant larvae fed Cy1Ac transgenic cotton or Cry1Ac-treated artificial diet had lower esterase activity than non-Cry1Ac-fed larvae. A resistance mechanism in which esterase sequesters Cry1Ac is proposed.

  9. Evaluation of E-J characteristics of YBCO coated-conductor by AC inductive method using third-harmonic voltage

    Energy Technology Data Exchange (ETDEWEB)

    Fukumoto, Yosuke; Kiuchi, M.; Otabe, E.S.; Matsushita, T.; Sawa, H.; Inoue, M.; Kiss, T.; Iijima, Y.; Kakimoto, K.; Saitoh, T

    2004-10-01

    The E-J characteristics were measured for a YBCO coated-conductor by using AC inductive method of third-harmonic voltage. The results are compared with the measurements obtained by the four probe method and DC relaxation method of magnetization. The results by three kinds of measurements meet approximately on a single curve and E-J curve in a wide range of electric field is obtained. Hence, the third-harmonic voltage method is useful for a continuous measurement of J{sub c} property of long coated tape. The obtained E-J characteristics are argued.

  10. Study of the Dependence on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

    Science.gov (United States)

    Bandler, Simon

    2011-01-01

    At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in the AC bias configuration. For x-ray photons at 6keV the AC biased pixel shows a best energy resolution of 3.7eV, which is about a factor of 2 worse than the energy resolution observed in identical DC-biased pixels. To better understand the reasons of this discrepancy, we investigated the detector performance as a function of temperature, bias working point and applied magnetic field. A strong periodic dependence of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recent weak-link behaviour observed inTES microcalorimeters.

  11. Measurement of microchannel fluidic resistance with a standard voltage meter.

    Science.gov (United States)

    Godwin, Leah A; Deal, Kennon S; Hoepfner, Lauren D; Jackson, Louis A; Easley, Christopher J

    2013-01-03

    A simplified method for measuring the fluidic resistance (R(fluidic)) of microfluidic channels is presented, in which the electrical resistance (R(elec)) of a channel filled with a conductivity standard solution can be measured and directly correlated to R(fluidic) using a simple equation. Although a slight correction factor could be applied in this system to improve accuracy, results showed that a standard voltage meter could be used without calibration to determine R(fluidic) to within 12% error. Results accurate to within 2% were obtained when a geometric correction factor was applied using these particular channels. When compared to standard flow rate measurements, such as meniscus tracking in outlet tubing, this approach provided a more straightforward alternative and resulted in lower measurement error. The method was validated using 9 different fluidic resistance values (from ∼40 to 600kPa smm(-3)) and over 30 separately fabricated microfluidic devices. Furthermore, since the method is analogous to resistance measurements with a voltage meter in electrical circuits, dynamic R(fluidic) measurements were possible in more complex microfluidic designs. Microchannel R(elec) was shown to dynamically mimic pressure waveforms applied to a membrane in a variable microfluidic resistor. The variable resistor was then used to dynamically control aqueous-in-oil droplet sizes and spacing, providing a unique and convenient control system for droplet-generating devices. This conductivity-based method for fluidic resistance measurement is thus a useful tool for static or real-time characterization of microfluidic systems. Copyright © 2012 Elsevier B.V. All rights reserved.

  12. 单相电压型Z源AC/AC变流器电路%Single-Phase Voltage-Fed Z-Source AC/AC Converter

    Institute of Scientific and Technical Information of China (English)

    房绪鹏

    2006-01-01

    提出了一种新型AC/AC变流器电路--单相电压型Z源AC/AC变流器;介绍了其电路拓扑、工作原理、控制方法等;给出了相应的仿真和实验结果.仿真和实验证实了该电路拓扑的合理性和优越性.

  13. Thevenin source resistances of the touch, transferred and step voltages of a grounding system

    Energy Technology Data Exchange (ETDEWEB)

    Chow, Y.L.; Salama, M.M.A.; Djogo, G. [University of Waterloo, ON (Canada)

    1999-03-01

    The source resistances for surface voltages (touch, transferred and step voltage) are considered. It is proved that the source resistances of the touch and transferred voltages are the same, given by the grounding resistances between the feet of a human and the grounding system. In a practical situation, however, this resistance is very close to that of the ANSI/IEEE Standard 80 that is widely accepted. The source resistance of the step voltage is simply the resistance between the two feet, not at all perturbed by the grounding system. Proofs are derived rigorously by combining the field Galerkin's moment method and basic circuit theory. (author)

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

    DEFF Research Database (Denmark)

    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...

  15. Production and characterization of Bacillus thuringiensis Cry1Ac-resistant cotton bollworm Helicoverpa zea (Boddie).

    Science.gov (United States)

    Anilkumar, Konasale J; Rodrigo-Simón, Ana; Ferré, Juan; Pusztai-Carey, Marianne; Sivasupramaniam, Sakuntala; Moar, William J

    2008-01-01

    Laboratory-selected Bacillus thuringiensis-resistant colonies are important tools for elucidating B. thuringiensis resistance mechanisms. However, cotton bollworm, Helicoverpa zea, a target pest of transgenic corn and cotton expressing B. thuringiensis Cry1Ac (Bt corn and cotton), has proven difficult to select for stable resistance. Two populations of H. zea (AR and MR), resistant to the B. thuringiensis protein found in all commercial Bt cotton varieties (Cry1Ac), were established by selection with Cry1Ac activated toxin (AR) or MVP II (MR). Cry1Ac toxin reflects the form ingested by H. zea when feeding on Bt cotton, whereas MVP II is a Cry1Ac formulation used for resistance selection and monitoring. The resistance ratio (RR) for AR exceeded 100-fold after 11 generations and has been maintained at this level for nine generations. This is the first report of stable Cry1Ac resistance in H. zea. MR crashed after 11 generations, reaching only an RR of 12. AR was only partially cross-resistant to MVP II, suggesting that MVP II does not have the same Cry1Ac selection pressure as Cry1Ac toxin against H. zea and that proteases may be involved with resistance. AR was highly cross-resistant to Cry1Ab toxin but only slightly cross-resistant to Cry1Ab expressing corn leaf powder. AR was not cross-resistant to Cry2Aa2, Cry2Ab2-expressing corn leaf powder, Vip3A, and cypermethrin. Toxin-binding assays showed no significant differences, indicating that resistance was not linked to a reduction in binding. These results aid in understanding why this pest has not evolved B. thuringiensis resistance, and highlight the need to choose carefully the form of B. thuringiensis protein used in experiments.

  16. Characterisation of a Selection of AC and DC Resistance Bridges for Standard Platinum Resistance Thermometry

    Science.gov (United States)

    Pearce, J. V.; Gray, J.; Veltcheva, R. I.

    2016-11-01

    Accurate resistance bridges are used to measure the ratio between the resistance of standard platinum resistance thermometers and a reference (standard) resistor at the level of microkelvin in temperature terms and as such play a critical role in the realisation and dissemination of the ITS-90. For AC bridges, the ratio test unit has been available for some time, and for both AC and DC bridges, the increasing availability of resistance bridge calibrators based on combinatorial calibration has increased the ease with which the accuracy and linearity of resistance bridges may be determined, under conditions which provide a realistic representation of the actual measurement set-up. In this study, the performance of 14 resistance bridges, which were available for testing at NPL, consisting of a range of manufacturers and types, has been evaluated and expressed in terms of the standard deviation of the bridge errors over a given range of ratios, namely s. In general, the bridges are found to comply with the manufacturers' specifications. The uncertainty of s has also been determined using Monte Carlo techniques and is found to be of the order of 10 % of s for most bridge types.

  17. Study of the Dependency on Magnetic Field and Bias Voltage of an AC-Biased TES Microcalorimeter

    Science.gov (United States)

    Gottardi, L.; Bruijn, M.; denHartog, R.; Hoevers, H.; deKorte, P.; vanderKuur, J.; Linderman, M.; Adams, J.; Bailey, C.; Bandler, S.; Chervenak, J.; Eckart, M.; Finkbeiner, F.; Kelley, R.; Kilbourne, C.; Porter, F.; Sadlier, J.; Smith, S.

    2012-01-01

    At SRON we are studying the performance of a Goddard Space Flight Center single pixel TES microcalorimeter operated in an AC bias configuration. For x-ray photons at 6 keV the pixel shows an x-ray energy resolution Delta E(sub FWHM) = 3.7 eV, which is about a factor 2 worse than the energy resolution observed in an identical DC-biased pixel. In order to better understand the reasons for this discrepancy we characterized the detector as a function of temperature, bias working point and applied perpendicular magnetic field. A strong periodic dependency of the detector noise on the TES AC bias voltage is measured. We discuss the results in the framework of the recently observed weak-link behaviour of a TES microcalorimeter.

  18. Containment and Consensus-based Distributed Coordination Control to Achieve Bounded Voltage and Precise Reactive Power Sharing in Islanded AC Microgrids

    DEFF Research Database (Denmark)

    Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

    2017-01-01

    This paper presents a novel distributed approach to achieve both bounded voltage and accurate reactive power sharing regulation in AC microgrid. The coupling/trade-off effects between bus voltages and reactive power sharing regulation are first analyzed in detail to provide a guideline for coordi...

  19. Output stages inside a negative feedback loop: application to a low-voltage three-phase DC-AC converter for educational purposes

    CERN Document Server

    Llopis, Francisco

    2013-01-01

    The circuit presented in this paper aims at providing three 40 Vpp 50Hz AC voltages sources with 120-degree phase separation between them. This is a fully analogue circuit that uses standard, low-cost electronic components without resorting to a microcontroller as previously proposed by Shirvasar et al [1]. This circuit may serve as a basis for a low-voltage 3P-AC power supply that students may safely use to realize experiments, i.e. about the principles and applications of three-phase AC power lines, without the risk of electric shocks.

  20. Analysis of three-phase rectifiers with AC-side switches and interleaved three-phase voltage-source converters

    Science.gov (United States)

    Miller, Stephanie Katherine Teixeira

    Of all the alternative and renewable energy sources, wind power is the fastest growing alternative energy source with a total worldwide capacity of over 93 GW as of the end of 2007. However, making wind energy a sustainable and reliable source of electricity doesn't come without its set of challenges. As the wind turbines increase in size and turbine technology moves towards off-shore wind farms and direct drive transmission, the need for a reliable and efficient power electronics interface to convert the variable-frequency variable-magnitude output of the wind turbine's generator into the fixed-frequency fixed-magnitude voltage of the utility grid is critical. This dissertation investigates a power electronics interface envisioned to operate with an induction generator-based variable-speed wind turbine. The research conclusions and the interface itself are applicable to a variety of applications, including uninterruptible power supplies, industrial drives, and power quality applications, among others. The three-phase PWM rectifiers with ac-side bidirectional switches are proposed as the rectification stage of the power electronics interface. Modulation strategies are proposed for the rectifiers and the operation of the rectifiers in conjunction with an induction generator is demonstrated. The viability of using these rectifiers in place of the standard three-phase voltage-source converter is analyzed by comparing losses and common-mode voltage generation of the two topologies. Parallel three-phase voltage-source converter modules operated in an interleaved fashion are proposed for the inversion stage of the power electronics interface. The interleaved three-phase voltage-source converters are analyzed by deriving analytical models for the common-mode voltage, ac phase current, and dc-link current to reveal their spectra and the harmonic cancellation effects of interleaving. The practical problem of low frequency circulating current in parallel voltage

  1. KEY COMPARISON Final report on APMP international comparison APMP.EM-K9: High voltage AC-DC transfer standards

    Science.gov (United States)

    Wei, Yih-Cheng; Yeh, Hsin-Da

    2010-01-01

    The international key comparison APMP.EM-K9 of AC-DC high voltage transfer standards with 12 participants was carried out from June 2000 to January 2004. This comparison offers the same range and frequencies as BIPM key comparison CCEM-K9, voltages at 500 V and 1000 V, frequency from 1 kHz to 100 kHz. This comparison provides the national metrology institutes (NMIs) of the APMP member economies with an opportunity to link the values of their standards for AC-DC transfer difference to the international reference values. The results of the majority of the participating NMIs show an agreement with the reference value within the associated expanded uncertainty given by the individual NMI. The agreement of the results and the tables of the degree of equivalence of the participants are included. The results have been linked to the key comparison CCEM-K9. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  2. Robust Frequency and Voltage Stability Control Strategy for Standalone AC/DC Hybrid Microgrid

    Directory of Open Access Journals (Sweden)

    Furqan Asghar

    2017-05-01

    Full Text Available The microgrid (MG concept is attracting considerable attention as a solution to energy deficiencies, especially in remote areas, but the intermittent nature of renewable sources and varying loads cause many control problems and thereby affect the quality of power within a microgrid operating in standalone mode. This might cause large frequency and voltage deviations in the system due to unpredictable output power fluctuations. Furthermore, without any main grid support, it is more complex to control and manage the system. In past, droop control and various other coordination control strategies have been presented to stabilize the microgrid frequency and voltages, but in order to utilize the available resources up to their maximum capacity in a positive way, new and robust control mechanisms are required. In this paper, a standalone microgrid is presented, which integrates renewable energy-based distributed generations and local loads. A fuzzy logic-based intelligent control technique is proposed to maintain the frequency and DC (direct current-link voltage stability for sudden changes in load or generation power. Also from a frequency control perspective, a battery energy storage system (BESS is suggested as a replacement for a synchronous generator to stabilize the nominal system frequency as a synchronous generator is unable to operate at its maximum efficiency while being controlled for stabilization purposes. Likewise, a super capacitor (SC and BESS is used to stabilize DC bus voltages even though maximum possible energy is being extracted from renewable generated sources using maximum power point tracking. This newly proposed control method proves to be effective by reducing transient time, minimizing the frequency deviations, maintaining voltages even though maximum power point tracking is working and preventing generators from exceeding their power ratings during disturbances. However, due to the BESS limited capacity, load switching

  3. Spin Backflow and ac Voltage Generation by Spin Pumping and the Inverse Spin Hall Effect

    NARCIS (Netherlands)

    Jiao, H.; Bauer, G.E.W.

    2013-01-01

    The spin current pumped by a precessing ferromagnet into an adjacent normal metal has a constant polarization component parallel to the precession axis and a rotating one normal to the magnetization. The former is now routinely detected as a dc voltage induced by the inverse spin Hall effect (ISHE).

  4. Breakdown Characteristic Analysis of Paper- Oil Insulation under AC and DC Voltage

    Science.gov (United States)

    Anuar, N. F.; Jamail, N. A. M.; Rahman, R. A.; Kamarudin, M. S.

    2017-08-01

    This paper presents the study of breakdown characteristic of Kraft paper insulated with two different types of insulating fluid, which are Palm oil and Coconut oil. Palm oil and Coconut oil are chosen as the alternative fluid to the transformer oil because it has high potential and environmentally-friendly. The Segezha Kraft papers with various thicknesses (65.5 gsm, 75 gsm, 85gsm, 90 gsm) have been used in this research. High Voltage Direct Current (HVDC), High Voltage Alternating Current (HVAC) and carbon track and severity analysis is conducted to observe the sample of aging Kraft paper. These samples have been immersed using Palm oil and Coconut oil up to 90 days to observe the absorption rate. All samples started to reach saturation level at 70 days of immersion. HVDC and HVAC breakdown experiments have been done after the samples had reached the saturation level based on normal condition, immersed in Palm oil and immersed in Coconut oil. All samples immersed in liquid show different breakdown voltage reading compared to normal condition. The analysis of carbon track and severity on surface has been done using Analytical Scanning Electron Microscope (SEM) Analysis. The results of the experiment show that the sample of Kraft paper immersed in Palm oil was better than Coconut oil immersed sample. Therefore the sample condition was the main factor that determines the value of breakdown voltage test. Introduction

  5. Modulation Voltage of High T c DC Superconducting Quantum Interference Device with Damping Resistance

    Science.gov (United States)

    Enpuku, Keiji; Doi, Hideki; Tokita, Go; Maruo, Taku

    1994-05-01

    The effect of damping resistance on the voltage versus flux (V -Φ) relation of the high T c dc superconducting quantum interference device (SQUID) is studied experimentally. Dc SQUID using YBaCuO step-edge junction and damping resistance in parallel with SQUID inductance is fabricated. Measured values of modulation voltage in the V -Φ relation are compared with those of the conventional SQUID without damping resistance. It is shown that modulation voltage is much improved by using damping resistance. The obtained experimental results agree reasonably with theoretical predictions reported previously.

  6. Coordinated Reactive Power and Voltage Management for Offshore Wind Farms with AC-connection

    DEFF Research Database (Denmark)

    Heussen, Kai

    2008-01-01

    This paper analyzes voltage and reactive power in a wind farm in dependence on switchable shunt and tap-changer settings in connection with the control ranges of flexible reactive power sources. Attention is paid to their interdependent effects on central control variables, such as voltage...... in the collection grid, reactive power exported to the grid and internal active power losses. An aggregated steady-state model of an offshore wind farm is presented and a reduced mathematical representation suitable for symbolic analysis is developed. A coordination scheme is proposed to coordinate fast continuous...... control inputs with slow tap-changing devices using a short-term prediction. The proposed scheme is aimed at balancing cost factors such as wear of switching components, active power loss within the wind farm and STATCOM capacity....

  7. Investigation of surface modifications in ethylene propylene diene monomer (EPDM) rubber due to tracking under a.c. and d.c. voltages

    Indian Academy of Sciences (India)

    R Sarathi; Uma Maheswar Rao

    2001-12-01

    In the present work, tracking phenomena has been studied with the ethylene propylene diene monomer (EPDM) material under the a.c. and d.c. voltages, with ammonium chloride/acid rain solution as the contaminant. It is noticed that the tracking time depends on the conductivity and flow rate of the contaminant. The physico-chemical analyses viz. wide angle X-ray diffraction (WAXD), thermo-gravimetric differential thermal analysis (TG-DTA) and the differential scanning calorimetry (DSC) studies, were carried out and it was concluded that the tracking process is a surface degradation process. The tracking time is different for a.c. and d.c. voltages.

  8. Modelling of long High Voltage AC Cables in the Transmission System

    DEFF Research Database (Denmark)

    Gudmundsdottir, Unnur Stella

    , EMTDC/PSCAD is provided. A typical HV AC underground power cable is formed by 4 main layers, namely; Conductor-Insulation-Screen-Insulation. In addition to these main layers, the cable also has semiconductive screens, swelling tapes and metal foil. For high frequency modelling in EMT-based software...... and field measurement results. This is because of intersheath mode reflecting from the crossbonding points. The second main part of the work deals with improving the cable model based on the findings from analysis of the field measurements. The existing EMT-based models have the configuration for cables...

  9. Analysis and simulation of the three-phase AC voltage regulation circuit%三相交流调压电路的分析与仿真

    Institute of Scientific and Technical Information of China (English)

    李衍孜

    2012-01-01

    Based on the analysis of the operation principle and mode of the single-phase AC voltage-regulation circuit, the voltage-regulating rule and effect of three-phase AC voltage-regulation was studied deeply in the paper. The theory of the three-phase star-style AC voltage-regulation circuit was tested in matlab/simulink, the simulation result proved the analysis of the theory of the three-phase AC voltage-regulation circuit was correct.%在分析单相交流调压电路运行原理和工作方式的基础上,深入研究了三相交流调压电路的调压规律和调压效果,并在Matlab/simulink仿真平台上对三相星形无中线交流调压电路的理论部分进行了验证,结果表明:三相交流调压电路的分析是正确的.

  10. Characteristics of Overvoltage Protection with Cascade Application of Surge Protective Devices in Low-Voltage AC Power Circuits

    Directory of Open Access Journals (Sweden)

    RADULOVIC, V.

    2015-08-01

    Full Text Available Surge Protective Devices (SPDs are widely used for protection of the equipment in low-voltage AC power circuits against wide variety of surges. Cascade application of SPDs starting at the service entrance of a building and downstream toward near sensitive equipment is intended to ensure optimal energy distribution among installed SPDs, as well as proper equipment protection against surges. Characteristics of overvoltage protection with two-stage application of SPDs have been analyzed in the paper through performed measurements, followed by simulations and numerical modeling using the ATP/EMTP and MATLAB Simulink. Parametric analysis of the protection's characteristics in wide range of influencing factors has been performed in order to define a set of applicable solutions for proper selection and performance of SPDs.

  11. Multi-Agent-Based Controller for Voltage Enhancement in AC/DC Hybrid Microgrid Using Energy Storages

    Directory of Open Access Journals (Sweden)

    Ahmadali Khatibzadeh

    2017-02-01

    Full Text Available Development of renewable energies and DC loads have led microgrids toward the creation of DC networks. The predictions show that the hybrid microgrids will be used widely in the future. This article has studied the voltage stability in the presence of sources of energy storage in AC/DC hybrid networks. However, because the different dynamics of hybrid networks applying centralized and distributed controllers will be faced with different problems, in this study, a multi-agent control for the microgrid has been used. A new structure referred to here as an event-driven microgrid control management (EDMCM has been developed to control the microgrid. This method increases response speed and accuracy of decision making. Hybrid Network Simulation results confirm the validity of the developed model.

  12. Effect of Circuit Breaker Shunt Resistance on Chaotic Ferroresonance in Voltage Transformer

    Directory of Open Access Journals (Sweden)

    RADMANESH, H.

    2010-08-01

    Full Text Available Ferroresonance or nonlinear resonance is a complex electrical phenomenon, which may cause over voltages and over currents in the electrical power system which endangers the system reliability and continuous safe operating. This paper studies the effect of circuit breaker shunt resistance on the control of chaotic ferroresonance in a voltage transformer. It is expected that this resistance generally can cause ferroresonance dropout. For confirmation this aspect Simulation has been done on a one phase voltage transformer rated 100VA, 275kV. The magnetization characteristic of the transformer is modeled by a single-value two-term polynomial with q=7. The simulation results reveal that considering the shunt resistance on the circuit breaker, exhibits a great mitigating effect on ferroresonance over voltages. Significant effect on the onset of chaos, the range of parameter values that may lead to chaos along with ferroresonance voltages has been obtained and presented.

  13. Negative-resistance voltage-current characteristics of superconductor contact junctions for macro-scale applications

    CERN Document Server

    Takayasu, M; Minervini, J V; 10.1109/TASC.2003.812854

    2003-01-01

    Voltage-current characteristics of mechanical pressure contact junctions between superconducting wires are investigated using a voltage-driving method. It is found that the switching regions at low voltages result from negative resistance of the contact junction. The current transport of the contact junctions is discussed from the perspective of two existing models: the multiple Andreev reflections at the two SN interfaces of a SNS (Superconductor/Normal metal /Superconductor) junction and the inhomogeneous multiple Josephson weak-link array. (13 refs).

  14. The influence of transformers, induction motors and fault resistance regarding propagation voltage sags

    Directory of Open Access Journals (Sweden)

    Jairo Blanco

    2011-07-01

    Full Text Available This article presents an analysis of voltage sag propagation. The ATPDraw tool was selected for simulating the IEEE 34 node test feeder. It takes into account both voltage sags caused by electrical fault network, as well as voltage sag propagation characteristics caused by induction motor starting and transformer energising. The analysis was aimed at assessing the influence of transformer winding connections, the impedance of these transformers, lines and cables, summarising the effects on disturbance magnitude and phase. The study shows that the influence of an induction motor on voltage sag propagation results in increased voltage sag severity. Voltage sags caused by induction motor starting and transformer energising have no zero-sequence component, so they are only affected by type 3 transformers. The influence of fault resistance on voltage sag magnitude and phase characteristics is examined and some aspects of interest in characterising these electromagnetic disturbances is identified.

  15. Overmodulation of n-level three-leg DC-AC diode-clamped converters with comprehensive capacitor voltage balance

    DEFF Research Database (Denmark)

    Busquets-Monge, S.; Maheshwari, Ram Krishan; Munk-Nielsen, Stig

    2013-01-01

    This paper presents a novel PWM strategy for nlevel three-leg semiconductor-clamped dc-ac converters in the overmodulation region, with dc-link capacitor voltage balance in every switching cycle. The strategy is based on the virtual-vector concept. Suitable reference vector trajectories are selec...

  16. Voltage-Induced Effect on Resistance of C:N/Si Heterojunctions

    Institute of Scientific and Technical Information of China (English)

    GAO Xi-Li; ZHANG Xiao-Zhong; WAN Cai-Hua; WANG Ji-Min

    2012-01-01

    Nitrogen doped a-C/Silicon (a-C:N/Si) heterojunctions have been fabricated by using the pulsed laser deposition (PLD) technique and their current-voltage characteristics at various temperatures are investigated.For reverse applied voltages,a-C:N/Si heterojunctions exhibit metal-insulator transition characteristics and the transition temperature can be controlled by the applied voltages.After the excitation of repeated high reverse applied voltages,the current-voltage curves show obvious hysteresis behaviors at low temperatures.These hysteresis behaviors are reproducible and the ratio of the high/low resistance can be greater than 104.%Nitrogen doped a-C/Silicon (a-C:N/Si) heterojunctions have been fabricated by using the pulsed laser deposition (PLD) technique and their current-voltage characteristics at various temperatures are investigated. For reverse applied voltages, a-C.N/Si heterojunctions exhibit metal-insulator transition characteristics and the transition temperature can be controlled by the applied voltages. After the excitation of repeated high reverse applied voltages, the current-voltage curves show obvious hysteresis behaviors at low temperatures. These hysteresis behaviors are reproducible and the ratio of the high/low resistance can be greater than 104.

  17. Reversible voltage dependent transition of abnormal and normal bipolar resistive switching

    Science.gov (United States)

    Wang, Guangyu; Li, Chen; Chen, Yan; Xia, Yidong; Wu, Di; Xu, Qingyu

    2016-11-01

    Clear understanding the mechanism of resistive switching is the important prerequisite for the realization of high performance nonvolatile resistive random access memory. In this paper, binary metal oxide MoOx layer sandwiched by ITO and Pt electrodes was taken as a model system, reversible transition of abnormal and normal bipolar resistive switching (BRS) in dependence on the maximum voltage was observed. At room temperature, below a critical maximum voltage of 2.6 V, butterfly shaped I-V curves of abnormal BRS has been observed with low resistance state (LRS) to high resistance state (HRS) transition in both polarities and always LRS at zero field. Above 2.6 V, normal BRS was observed, and HRS to LRS transition happened with increasing negative voltage applied. Temperature dependent I-V measurements showed that the critical maximum voltage increased with decreasing temperature, suggesting the thermal activated motion of oxygen vacancies. Abnormal BRS has been explained by the partial compensation of electric field from the induced dipoles opposite to the applied voltage, which has been demonstrated by the clear amplitude-voltage and phase-voltage hysteresis loops observed by piezoelectric force microscopy. The normal BRS was due to the barrier modification at Pt/MoOx interface by the accumulation and depletion of oxygen vacancies.

  18. Proposal of indexes for fast voltage stability evaluation of ac/dc transmission systems

    Directory of Open Access Journals (Sweden)

    Jorge Wilson González

    2011-01-01

    Full Text Available En este artículo se desarrolla un análisis de estabilidad de tensión de sistemas ca/cd empleando indicadores estáticos y modales. Se propone un tratamiento novedoso para indicadores de estabilidad de tensión, con el fin de obtener una mayor información sobre los requerimientos en redes de variadas fortalezas, en términos de la estabilidad de tensión. El nuevo tratamiento se ofrece como un medio para prevenir potenciales problemas en redes de transmisión de corriente directa, High Voltage dc Transmission Systems (HVdc, conectados a nodos débiles. Los indicadores son convertidos a por unidad y comparados en diferentes relaciones de corto circuito, Short Circuit Ratios (SCR, en una red modificada tipo IEEE de 14 barras, la cual posee un sistema HVdc conectado en su barra más débil. Los alcances pueden servir tanto para planeamiento como para monitoreo en tiempo real de la estabilidad de tensión en sistemas eléctricos de potencia incluyendo nodos ca/cd.

  19. Non-isolated DC-AC converter with high voltage gain for autonomous systems of electric power; Conversor CC-CA nao isolado com alto ganho de tensao para aplicacao em sistemas autonomos de energia eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, George Cajazeiras [Centro Federal de Educacao Tecnologica do Ceara (CEFET/CE), Fortaleza, CE (Brazil); Torrico-Bascope, Rene P. [Universidade Federal do Ceara (PPGEE/UFC), Fortaleza, CE (Brazil). Programa de Pos Graduacao em Engenharia Eletrica; Borges Neto, Manuel Rangel [Centro Federal de Educacao Tecnologica de Petrolina (CEFET-PET), PE (Brazil)

    2008-07-01

    A non-isolated DC-AC converter with high voltage gain with two output sinusoidal voltage - 110 V and 220 V - and frequency 60 Hz for application in autonomous systems of electric power is proposed in this work. This topology consists of a boost converter with high voltage gain, based on three-state switching cell combined with a double half bridge inverter. This configuration type the size and the cost are reduced and the efficiency is gotten better, due to the reduced number of switches. The converters that compose this topology operate with high frequency, reducing the volume of the magnetic materials. can be mention as important characteristics: the voltage stress across the switches of the boost converter are low, due they be naturally clamped by one output filter capacitor, which allows the utilization of switches with lower conduction resistances, and the waveforms of the output voltage of the double half bridge inverter supplies for the load it is sinusoidal and it possesses low harmonic content. (author)

  20. Single-phase dynamic voltage restorer based on a new chopper AC/DC/AC conversion%一种新型斩波 AC/DC/AC 变换的单相 DVR

    Institute of Scientific and Technical Information of China (English)

    巫付专; 侯婷婷; 韩梁; 冯占伟

    2015-01-01

    针对输入侧采用不可控整流AC/DC/AC结构的单相动态电压恢复器( DVR )输入侧功率因数低,谐波含量高等问题,提出了一种基于PWM斩波变换器的动态电压恢复器来补偿负载两端电压的跌落。该新型拓扑结构采用PWM斩波控制节省了直流侧电容,简化了滤波器设计,使输入侧线路中谐波含量降低,同时达到单位功率因数;电压检测采用单相信号构造成两相信号,利用瞬时无功理论对信号进行检测与处理,实时性高;搭建MATLAB/Simulink仿真和系统实验平台,验证其合理性和可行性。%In view of such problems as the low input side power factor of the single-phase dynamic voltage restorer ( DVR) with the structure of uncontrolled rectifier AC/DC/AC and high harmonic content , this paper proposed a DVR based on the PWM chopper to compensate for the voltage drop at the two load ends .The new topology , which a-dopted the PWM chopper control , saved the DC capacitor and simplified the filter design so that the harmonic content in the input-side circuit was reduced and the input side achieved the unit power factor .Single-phase signals were con-structed into two-phase signals to detect voltage and the instantaneous reactive power theory was used to detect and process the signals , which attained high real time .Finally, a MATLAB/Simulink simulation and experimental plat-form was constructed to verify the rationality and feasibility of the new structure .

  1. A Survey of High Performance AC Voltage Regulating Technologies%高性能交流电压调节技术的发展概况

    Institute of Scientific and Technical Information of China (English)

    刘汉奎; 顾建军; 徐殿国; 王炎

    2000-01-01

    分析了交流斩波型、单位功率因数变换器 型和串联 型三类开关型交流电压调节装置,并给出了它们的新型拓扑结构。通过对这三种电压调节装 置的对比研究,指出串联型电压调节装置的性能价格比高于其他方式。串并联型电压调节装 置是交流电压调节装置的一个发展方向。%AC chopping voltage regulator,voltage regulator with unity power factor converter and series voltage regulator are analyzed,an d new topologies of each method are shown in this paper.It is pointed out that s eries voltage regulator has higher performance cost ratio,and series and parall el voltage regulator is a trend of AC voltage regulator.

  2. Line-to-line voltage based modulation scheme for single-phase reduced switch ac-dc-ac converters to achieve improved performance

    DEFF Research Database (Denmark)

    Qin, Zian; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    . With the SVPWM or DPWM proposed in literatures, the generation of the references is phase voltage based. But the phase voltages actually cannot be controlled directly by the PWM converter, since they can be influenced by both of terminal voltages and the load network while the PWM converter can only control...

  3. 30 CFR 75.803 - Fail safe ground check circuits on high-voltage resistance grounded systems.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fail safe ground check circuits on high-voltage resistance grounded systems. 75.803 Section 75.803 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... High-Voltage Distribution § 75.803 Fail safe ground check circuits on high-voltage resistance...

  4. An ABC transporter mutation is correlated with insect resistance to Bacillus thuringiensis Cry1Ac toxin.

    Directory of Open Access Journals (Sweden)

    Linda J Gahan

    2010-12-01

    Full Text Available Transgenic crops producing insecticidal toxins from Bacillus thuringiensis (Bt are commercially successful in reducing pest damage, yet knowledge of resistance mechanisms that threaten their sustainability is incomplete. Insect resistance to the pore-forming Cry1Ac toxin is correlated with the loss of high-affinity, irreversible binding to the mid-gut membrane, but the genetic factors responsible for this change have been elusive. Mutations in a 12-cadherin-domain protein confer some Cry1Ac resistance but do not block this toxin binding in in vitro assays. We sought to identify mutations in other genes that might be responsible for the loss of binding. We employed a map-based cloning approach using a series of backcrosses with 1,060 progeny to identify a resistance gene in the cotton pest Heliothis virescens that segregated independently from the cadherin mutation. We found an inactivating mutation of the ABC transporter ABCC2 that is genetically linked to Cry1Ac resistance and is correlated with loss of Cry1Ac binding to membrane vesicles. ABC proteins are integral membrane proteins with many functions, including export of toxic molecules from the cell, but have not been implicated in the mode of action of Bt toxins before. The reduction in toxin binding due to the inactivating mutation suggests that ABCC2 is involved in membrane integration of the toxin pore. Our findings suggest that ABC proteins may play a key role in the mode of action of Bt toxins and that ABC protein mutations can confer high levels of resistance that could threaten the continued utilization of Bt-expressing crops. However, such mutations may impose a physiological cost on resistant insects, by reducing export of other toxins such as plant secondary compounds from the cell. This weakness could be exploited to manage this mechanism of Bt resistance in the field.

  5. An ABC transporter mutation is correlated with insect resistance to Bacillus thuringiensis Cry1Ac toxin.

    Science.gov (United States)

    Gahan, Linda J; Pauchet, Yannick; Vogel, Heiko; Heckel, David G

    2010-12-16

    Transgenic crops producing insecticidal toxins from Bacillus thuringiensis (Bt) are commercially successful in reducing pest damage, yet knowledge of resistance mechanisms that threaten their sustainability is incomplete. Insect resistance to the pore-forming Cry1Ac toxin is correlated with the loss of high-affinity, irreversible binding to the mid-gut membrane, but the genetic factors responsible for this change have been elusive. Mutations in a 12-cadherin-domain protein confer some Cry1Ac resistance but do not block this toxin binding in in vitro assays. We sought to identify mutations in other genes that might be responsible for the loss of binding. We employed a map-based cloning approach using a series of backcrosses with 1,060 progeny to identify a resistance gene in the cotton pest Heliothis virescens that segregated independently from the cadherin mutation. We found an inactivating mutation of the ABC transporter ABCC2 that is genetically linked to Cry1Ac resistance and is correlated with loss of Cry1Ac binding to membrane vesicles. ABC proteins are integral membrane proteins with many functions, including export of toxic molecules from the cell, but have not been implicated in the mode of action of Bt toxins before. The reduction in toxin binding due to the inactivating mutation suggests that ABCC2 is involved in membrane integration of the toxin pore. Our findings suggest that ABC proteins may play a key role in the mode of action of Bt toxins and that ABC protein mutations can confer high levels of resistance that could threaten the continued utilization of Bt-expressing crops. However, such mutations may impose a physiological cost on resistant insects, by reducing export of other toxins such as plant secondary compounds from the cell. This weakness could be exploited to manage this mechanism of Bt resistance in the field.

  6. Optimal planning of series resistor to control time constant of test circuit for high-voltage AC circuit-breakers

    Directory of Open Access Journals (Sweden)

    Yoon-Ho Kim

    2016-01-01

    Full Text Available The equivalent test circuit that can deliver both short-circuit current and recovery voltage is used to verify the performance of high-voltage circuit breakers. Most of the parameters in this circuit can be obtained by using a simple calculation or a simulation program. The ratings of the circuit breaker include rated short-circuit breaking current, rated short-circuit making current, rated operating sequence of the circuit breaker and rated short-time current. Among these ratings, the short-circuit making capacity of the circuit breaker is expressed in peak value and not in RMS value similar to breaking capacity. A series resistor or super-excitation is used to control the peak value of the short-circuit current in the equivalent test circuit. When using a series resistor, a higher rating of circuit breakers leads to a higher thermal capacity, thereby requiring additional space. Therefore, an effective, optimal design of the series resistor is essential. This paper proposes a method for reducing thermal capacity and selecting the optimal resistance to limit the making current by controlling the DC time constant of the test circuit.

  7. Cross-resistance and interactions between Bt toxins Cry1Ac and Cry2Ab against the cotton bollworm.

    Science.gov (United States)

    Wei, Jizhen; Guo, Yuyuan; Liang, Gemei; Wu, Kongming; Zhang, Jie; Tabashnik, Bruce E; Li, Xianchun

    2015-01-14

    To delay evolution of pest resistance to transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt), the "pyramid" strategy uses plants that produce two or more toxins that kill the same pest. We conducted laboratory diet experiments with the cotton bollworm, Helicoverpa armigera, to evaluate cross-resistance and interactions between two toxins in pyramided Bt cotton (Cry1Ac and Cry2Ab). Selection with Cry1Ac for 125 generations produced 1000-fold resistance to Cry1Ac and 6.8-fold cross-resistance to Cry2Ab. Selection with Cry2Ab for 29 generations caused 5.6-fold resistance to Cry2Ab and 61-fold cross-resistance to Cry1Ac. Without exposure to Bt toxins, resistance to both toxins decreased. For each of the four resistant strains examined, 67 to 100% of the combinations of Cry1Ac and Cry2Ab tested yielded higher than expected mortality, reflecting synergism between these two toxins. Results showing minor cross-resistance to Cry2Ab caused by selection with Cry1Ac and synergism between these two toxins against resistant insects suggest that plants producing both toxins could prolong the efficacy of Bt cotton against this pest in China. Including toxins against which no cross-resistance occurs and integrating Bt cotton with other control tactics could also increase the sustainability of management strategies.

  8. Hp-Hgs Strategy For Inverse Ac/Dc Resistivity Logging Measurement Simulations

    Directory of Open Access Journals (Sweden)

    Ewa Gajda-Zagorska

    2013-01-01

    Full Text Available In this paper we present resistivity logging measurement simulation with the usage of two types of borehole logging devices: operating with zero frequency (direct current, DC and those operating with higher frequencies (alternate current, AC. We perform simulations of 3D resistivity measurements in deviated wells, with the sharp angle between the borehole and formation layers. We introduce hierarchical adaptive genetic strategy $hp-HGS$ interfaced with adaptive finite element method. We apply the strategy for the solution of the inverse problem, where we identify the resistivities of the formation layers based on a given measurement. We test the strategy on both direct and accurate currect cases.

  9. A new low voltage level-shifted FVF current mirror with enhanced bandwidth and output resistance

    Science.gov (United States)

    Aggarwal, Bhawna; Gupta, Maneesha; Gupta, Anil Kumar; Sangal, Ankur

    2016-10-01

    This paper proposes a new high-performance level-shifted flipped voltage follower (LSFVF) based low-voltage current mirror (CM). The proposed CM utilises the low-supply voltage and low-input resistance characteristics of a flipped voltage follower (FVF) CM. In the proposed CM, level-shifting configuration is used to obtain a wide operating current range and resistive compensation technique is employed to increase the operating bandwidth. The peaking in frequency response is reduced by using an additional large MOSFET. Moreover, a very high output resistance (in GΩ range) along with low-current transfer error is achieved through super-cascode configuration for a wide current range (0-440 µA). Small signal analysis is carried out to show the improvements achieved at each step. The proposed CM is simulated by Mentor Graphics Eldospice in TSMC 0.18 µm CMOS, BSIM3 and Level 53 technology. In the proposed CM, a bandwidth of 6.1799 GHz, 1% settling time of 0.719 ns, input and output resistances of 21.43 Ω and 1.14 GΩ, respectively, are obtained with a single supply voltage of 1 V. The layout of the proposed CM has been designed and post-layout simulation results have been shown. The post-layout simulation results for Monte Carlo and temperature analysis have also been included to show the reliability of the CM against the variations in process parameters and temperature changes.

  10. Design of wide output voltage AC-DC power supply based on buck-boost circuit%基于Buck-Boost电路的宽输出电压AC-DC电源设计

    Institute of Scientific and Technical Information of China (English)

    徐文城; 刘尧; 王秀荣

    2012-01-01

    设计了一种宽输出电压的AC DC开关电源,其主要特征是输出电压可以在较大范围内任意调节,解决了传统的开关电源只能输出几个特定电压值的问题.该设计的核心是反激变换电路和Buck-Boost电路.分析了这两种电路的工作原理及其应用,并且给出了具体的设计.实验表明,设计的电源能较好地实现了输出电压的宽范围调节.%AC-DC switching power supply with a wide range voltage output was designed. Its main feature is that the output voltage can be adjusted in a wide range. The problem that the traditional switching power supplies only have few specific voltage outputs is solved in the design. The flyback convert circuit and Buck-Boost circuit are the cores of the design. The working principle and applications of these two circuits are analyzed. The concrete design is given in this paper. The experiments show that a wide range regulation of the output voltage has been more successfully achieved in the design of the power supply.

  11. Insulation Resistance and Leakage Currents in Low-Voltage Ceramic Capacitors with Cracks

    Science.gov (United States)

    Teverovsky, Alexander A.

    2016-01-01

    Measurement of insulation resistance (IR) in multilayer ceramic capacitors (MLCCs) is considered a screening technique that ensures the dielectric is defect-free. This work analyzes the effectiveness of this technique for revealing cracks in ceramic capacitors. It is shown that absorption currents prevail over the intrinsic leakage currents during standard IR measurements at room temperature. Absorption currents, and consequently IR, have a weak temperature dependence, increase linearly with voltage (before saturation), and are not sensitive to the presence of mechanical defects. In contrary, intrinsic leakage currents increase super-linearly with voltage and exponentially with temperature (activation energy is in the range from 0.6 eV to 1.1 eV). Leakage currents associated with the presence of cracks have a weaker dependence on temperature and voltage compared to the intrinsic leakage currents. For this reason, intrinsic leakage currents prevail at high temperatures and voltages, thus masking the presence of defects.

  12. Increased frequency of pink bollworm resistance to Bt toxin Cry1Ac in China.

    Directory of Open Access Journals (Sweden)

    Peng Wan

    Full Text Available Transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt kill some key insect pests, but evolution of resistance by pests can reduce their efficacy. The main approach for delaying pest adaptation to Bt crops uses non-Bt host plants as "refuges" to increase survival of susceptible pests. To delay evolution of pest resistance to transgenic cotton producing Bt toxin Cry1Ac, the United States and some other countries have required refuges of non-Bt cotton, while farmers in China have relied on "natural" refuges of non-Bt host plants other than cotton. The "natural" refuge strategy focuses on cotton bollworm (Helicoverpa armigera, the primary target of Bt cotton in China that attacks many crops, but it does not apply to another major pest, pink bollworm (Pectinophora gossypiella, which feeds almost entirely on cotton in China. Here we report data showing field-evolved resistance to Cry1Ac by pink bollworm in the Yangtze River Valley of China. Laboratory bioassay data from 51 field-derived strains show that the susceptibility to Cry1Ac was significantly lower during 2008 to 2010 than 2005 to 2007. The percentage of field populations yielding one or more survivors at a diagnostic concentration of Cry1Ac increased from 0% in 2005-2007 to 56% in 2008-2010. However, the median survival at the diagnostic concentration was only 1.6% from 2008 to 2010 and failure of Bt cotton to control pink bollworm has not been reported in China. The early detection of resistance reported here may promote proactive countermeasures, such as a switch to transgenic cotton producing toxins distinct from Cry1A toxins, increased planting of non-Bt cotton, and integration of other management tactics together with Bt cotton.

  13. Increased frequency of pink bollworm resistance to Bt toxin Cry1Ac in China.

    Science.gov (United States)

    Wan, Peng; Huang, Yunxin; Wu, Huaiheng; Huang, Minsong; Cong, Shengbo; Tabashnik, Bruce E; Wu, Kongming

    2012-01-01

    Transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) kill some key insect pests, but evolution of resistance by pests can reduce their efficacy. The main approach for delaying pest adaptation to Bt crops uses non-Bt host plants as "refuges" to increase survival of susceptible pests. To delay evolution of pest resistance to transgenic cotton producing Bt toxin Cry1Ac, the United States and some other countries have required refuges of non-Bt cotton, while farmers in China have relied on "natural" refuges of non-Bt host plants other than cotton. The "natural" refuge strategy focuses on cotton bollworm (Helicoverpa armigera), the primary target of Bt cotton in China that attacks many crops, but it does not apply to another major pest, pink bollworm (Pectinophora gossypiella), which feeds almost entirely on cotton in China. Here we report data showing field-evolved resistance to Cry1Ac by pink bollworm in the Yangtze River Valley of China. Laboratory bioassay data from 51 field-derived strains show that the susceptibility to Cry1Ac was significantly lower during 2008 to 2010 than 2005 to 2007. The percentage of field populations yielding one or more survivors at a diagnostic concentration of Cry1Ac increased from 0% in 2005-2007 to 56% in 2008-2010. However, the median survival at the diagnostic concentration was only 1.6% from 2008 to 2010 and failure of Bt cotton to control pink bollworm has not been reported in China. The early detection of resistance reported here may promote proactive countermeasures, such as a switch to transgenic cotton producing toxins distinct from Cry1A toxins, increased planting of non-Bt cotton, and integration of other management tactics together with Bt cotton.

  14. Comparative Study of AC/DC High Voltage Transmissions%高压交直流输电比较研究

    Institute of Scientific and Technical Information of China (English)

    王红刚

    2011-01-01

    比较了高压交流输电和高压直流输电的差异,认为,输送同样的电能,高压直流输电损耗少的原因在于载流子在晶格势场中的能态低;由于载流子受到感应电场的作用,高压交流输电载流子在晶格势场中的能态将高于高压直流输电载流子的能态。不论高压交流输电还是高压直流输电都存在着趋肤效应,直流趋肤效应起源于载流子受到的霍尔电场力;交流趋肤效应起源于载流子除了受到霍尔电场力外,还受到了交变电场力的作用.%Comparing the differences between AC and DC high voltage transmissions,it is considered that the reason why the DC high voltage transmission has lower electrical loss in transmitting the same power is that its carriers have low energy state in lattice potential field.As the carriers being affected by induced electric field,carriers of AC will have higher energy state than that of DC in lattice potential field.No matter AC or DC high voltage transmission there is skin effect.The DC skin effect originates from Hall electric field force acting on the carriers,while the AC skin effect originates from not only Hall electric field,but the role of alternating electric field force.

  15. Frequency and voltage dependence dielectric properties, ac electrical conductivity and electric modulus profiles in Al/Co{sub 3}O{sub 4}-PVA/p-Si structures

    Energy Technology Data Exchange (ETDEWEB)

    Bilkan, Çiğdem, E-mail: cigdembilkan@gmail.com [Department of Physics, Faculty of Sciences, The University of Çankırı Karatekin, 18100 Çankırı (Turkey); Azizian-Kalandaragh, Yashar [Department of Physics, Faculty of Science, The University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of); Altındal, Şemsettin [Department of Physics, Faculty of Sciences, The University of Gazi, 06500 Ankara (Turkey); Shokrani-Havigh, Roya [Department of Physics, Faculty of Science, The University of Mohaghegh Ardabili, Ardabil (Iran, Islamic Republic of)

    2016-11-01

    In this research a simple microwave-assisted method have been used for preparation of cobalt oxide nanostructures. The as-prepared sample has been investigated by UV–vis spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM). On the other hand, frequency and voltage dependence of both the real and imaginary parts of dielectric constants (ε′, ε″) and electric modulus (M′ and M″), loss tangent (tanδ), and ac electrical conductivity (σ{sub ac}) values of Al/Co{sub 3}O{sub 4}-PVA/p-Si structures were obtained in the wide range of frequency and voltage using capacitance (C) and conductance (G/ω) data at room temperature. The values of ε′, ε″ and tanδ were found to decrease with increasing frequency almost for each applied bias voltage, but the changes in these parameters become more effective in the depletion region at low frequencies due to the charges at surface states and their relaxation time and polarization effect. While the value of σ is almost constant at low frequency, increases almost as exponentially at high frequency which are corresponding to σ{sub dc} and σ{sub ac}, respectively. The M′ and M″ have low values at low frequencies region and then an increase with frequency due to short-range mobility of charge carriers. While the value of M′ increase with increasing frequency, the value of M″ shows two peak and the peaks positions shifts to higher frequency with increasing applied voltage due to the decrease of the polarization and N{sub ss} effects with increasing frequency.

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

    Science.gov (United States)

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

    2016-11-01

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

  17. Voltage-controlling mechanisms in low-resistivity silicon solar cells - A unified approach

    Science.gov (United States)

    Weizer, V. G.; Swartz, C. K.; Hart, R. E.; Godlewski, M. P.

    1986-01-01

    An experimental technique is used to determine the relative values of the base and emitter components of the dark saturation current of six types of high-voltage low-resistivity silicon solar cells. One of the surprising findings is the suggestion that the magnitude of the minority-carrier mobility may be process-dependent.

  18. ELABORATION AND TESTING OF SOFTWARE FOR SIGNAL PROCESSING OF RESISTIVE HIGH VOLTAGE DIVIDER

    Directory of Open Access Journals (Sweden)

    Sit М.

    2009-12-01

    Full Text Available Mathematical tools and the software for input in the computer of signals of a resistive divider of a high voltage of the industrial frequency, providing a split-hair accuracy of measurement of parameters of the basic and harmonics which are divisible to the basic is developed.

  19. Analysis of resistance to Cry1Ac in field-collected pink bollworm, Pectinophora gossypiella (Lepidoptera:Gelechiidae), populations.

    Science.gov (United States)

    Ojha, Abhishek; Sree, K Sowjanya; Sachdev, Bindiya; Rashmi, M A; Ravi, K C; Suresh, P J; Mohan, Komarlingam S; Bhatnagar, Raj K

    2014-01-01

    High survivorship of pink bollworrm, Pectinophora gossypiella in bolls of Bollgard® cotton hybrids and resistance to Cry1Ac protein, expressed in Bollgard cotton were reported in field-populations collected from the state of Gujarat (western India) in 2010. We have found Cry1Ac-resistance in pink bollworm populations sourced from Bollgard and non-Bt cotton fields in the adjoining states of Maharashtra and Madhya Pradesh in Central India. Further, we observed reduced binding of labeled Cry1Ac protein to receptors localized on the brush-border membrane of pink bollworm larval strains with high tolerance to Cry1Ac. These strains were sourced from Bollgard and conventional cotton fields. A pooled Cry1Ac-resistant strain, further selected on Cry1Ac diet also showed significantly reduced binding to Cry1Ac protein. The reduced binding of Cry1Ac to receptors could be an underlying mechanism for the observed resistance in pink bollworm populations feeding on Bollgard hybrids.

  20. Asymmetrical cross-resistance between Bacillus thuringiensis toxins Cry1Ac and Cry2Ab in pink bollworm.

    Science.gov (United States)

    Tabashnik, Bruce E; Unnithan, Gopalan C; Masson, Luke; Crowder, David W; Li, Xianchun; Carrière, Yves

    2009-07-21

    Transgenic crops producing Bacillus thuringiensis (Bt) toxins kill some key insect pests and can reduce reliance on insecticide sprays. Sustainable use of such crops requires methods for delaying evolution of resistance by pests. To thwart pest resistance, some transgenic crops produce 2 different Bt toxins targeting the same pest. This "pyramid" strategy is expected to work best when selection for resistance to 1 toxin does not cause cross-resistance to the other toxin. The most widely used pyramid is transgenic cotton producing Bt toxins Cry1Ac and Cry2Ab. Cross-resistance between these toxins was presumed unlikely because they bind to different larval midgut target sites. Previous results showed that laboratory selection with Cry1Ac caused little or no cross-resistance to Cry2A toxins in pink bollworm (Pectinophora gossypiella), a major cotton pest. We show here, however, that laboratory selection of pink bollworm with Cry2Ab caused up to 420-fold cross-resistance to Cry1Ac as well as 240-fold resistance to Cry2Ab. Inheritance of resistance to high concentrations of Cry2Ab was recessive. Larvae from a laboratory strain resistant to Cry1Ac and Cry2Ab in diet bioassays survived on cotton bolls producing only Cry1Ac, but not on cotton bolls producing both toxins. Thus, the asymmetrical cross-resistance seen here does not threaten the efficacy of pyramided Bt cotton against pink bollworm. Nonetheless, the results here and previous evidence indicate that cross-resistance occurs between Cry1Ac and Cry2Ab in some key cotton pests. Incorporating the potential effects of such cross-resistance in resistance management plans may help to sustain the efficacy of pyramided Bt crops.

  1. Origin of dc voltage in type II superconducting flux pumps: field, field rate of change, and current density dependence of resistivity

    Science.gov (United States)

    Geng, J.; Matsuda, K.; Fu, L.; Fagnard, J.-F.; Zhang, H.; Zhang, X.; Shen, B.; Dong, Q.; Baghdadi, M.; Coombs, T. A.

    2016-03-01

    Superconducting flux pumps are the kind of devices which can generate direct current into superconducting circuit using external magnetic field. The key point is how to induce a dc voltage across the superconducting load by ac fields. Giaever (1966 IEEE Spectr. 3 117) pointed out flux motion in superconductors will induce a dc voltage, and demonstrated a rectifier model which depended on breaking superconductivity. van de Klundert et al (1981 Cryogenics 21 195, 267) in their review(s) described various configurations for flux pumps all of which relied on inducing the normal state in at least part of the superconductor. In this letter, following their work, we reveal that a variation in the resistivity of type II superconductors is sufficient to induce a dc voltage in flux pumps and it is not necessary to break superconductivity. This variation in resistivity is due to the fact that flux flow is influenced by current density, field intensity, and field rate of change. We propose a general circuit analogy for travelling wave flux pumps, and provide a mathematical analysis to explain the dc voltage. Several existing superconducting flux pumps which rely on the use of a travelling magnetic wave can be explained using the analysis enclosed. This work can also throw light on the design and optimization of flux pumps.

  2. 30 CFR 77.803 - Fail safe ground check circuits on high-voltage resistance grounded systems.

    Science.gov (United States)

    2010-07-01

    ... circuits on high-voltage resistance grounded systems. On and after September 30, 1971, all high-voltage, resistance grounded systems shall include a fail safe ground check circuit or other no less effective device... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fail safe ground check circuits on...

  3. Determination of Resistor Resistance According to Over-Voltage Criteria in 6–35 kV Mains

    Directory of Open Access Journals (Sweden)

    V. I. Glushko

    2010-01-01

    Full Text Available A new method has been developed  for selection of resistor type according to over-voltage criteria that includes methods for calculation of resistor resistance RN  and over-voltage ratio factor kп which are used for evaluation of protective resistance functions.

  4. Technology to improve catenary voltage stability for a.c. railways; Verfahren zur Verbesserung der Spannungshaltung bei Wechselstrombahnen

    Energy Technology Data Exchange (ETDEWEB)

    Zynovchenko, Andriy [Balfour Beatty Rail GmbH, Offenbach (Germany). Abt. Systemtechnik

    2011-04-15

    Catenary voltage is one of the most important criteria for the design of a railway electrification system. The lowest voltage limits defined by the customer or by EN 50163 and EN 50388 may not be violated. The presented novel technique for improvement of the catenary voltage allows the extension of feeding area of a substation. This makes possible a reduction of the number of substations and enhancement of redundancy grade. (orig.)

  5. Simplification Study of FE Model for 1000kV AC Transmission Line Insulator String Voltage and Grading Ring Surface Electric Field Distribution Calculation

    Directory of Open Access Journals (Sweden)

    Guoli Wang

    2013-09-01

    Full Text Available The finite element model of the 1000kV Ultra High Voltage (UHV AC transmission line porcelain insulator string voltage distribution and grading ring surface electric field distribution calculation has the characteristics of large size, complicated structure and various mediums. To insure the accuracy, related influencing factors should be considered to simplify the model reasonably for improving computational efficiency. A whole model and a simplified 3D finite element model of UHV AC transmission line porcelain insulator string were built. The influencing factors including tower, phase conductors, hardware fittings, yoke plate and phase interaction were considered in the analysis. And finally, the rationality of the simplified model was validated. The results comparison show that building a simplified model of three-phase bundled conductors within a certain length, simplifying the tower reasonably, omitting the hardware fittings and yoke plate and containing only single-phase insulator string model is feasible. The simplified model could replace the whole model to analyze the voltage distribution along the porcelain insulator string and the electric field distribution on the grading ring surface, and it can reduce the calculation scale, improve optimization efficiency of insulators string and grading ring parameters.

  6. Modeling and Design of DC Boost and AC Side Voltage Controllers in Asymmetrical Γ-Source Inverter

    OpenAIRE

    2014-01-01

    In this paper a control system is proposed to simultaneously control the voltage boost and output voltage of assymetrical Γ-Source Inverters. Dynamic model of the system is used to design the controllers. Voltage boost on assymetrical Γ-Source Inverters is done by voltage control of impedance network capacitor and the regulation of inverter shoot through duty cycle. Since the stability margin of the system is low due to the right half plane zero in its dynamic model, the design of fast contro...

  7. Common, but complex, mode of resistance of Plutella xylostella to Bacillus thuringiensis toxins Cry1Ab and Cry1Ac.

    Science.gov (United States)

    Sayyed, Ali H; Gatsi, Roxani; Ibiza-Palacios, M Sales; Escriche, Baltasar; Wright, Denis J; Crickmore, Neil

    2005-11-01

    A field collected population of Plutella xylostella (SERD4) was selected in the laboratory with Bacillus thuringiensis endotoxins Cry1Ac (Cry1Ac-SEL) and Cry1Ab (Cry1Ab-SEL). Both subpopulations showed similar phenotypes: high resistance to the Cry1A toxins and little cross-resistance to Cry1Ca or Cry1D. A previous analysis of the Cry1Ac-SEL showed incompletely dominant resistance to Cry1Ac with more than one factor, at least one of which was sex influenced. In the present study reciprocal mass crosses between Cry1Ab-SEL and a laboratory susceptible population (ROTH) provided evidence that Cry1Ab resistance was also inherited as incompletely dominant trait with more than one factor, and at least one of the factors was sex influenced. Analysis of single pair mating indicated that Cry1Ab-SEL was still heterogeneous for Cry1Ab resistance genes, showing genes with different degrees of dominance. Binding studies showed a large reduction of specific binding of Cry1Ab and Cry1Ac to midgut membrane vesicles of the Cry1Ab-SEL subpopulation. Cry1Ab-SEL was found to be more susceptible to trypsin-activated Cry1Ab toxin than protoxin, although no defect in toxin activation was found. Present and previous results indicate a common basis of resistance to both Cry1Ab and Cry1Ac in selected subpopulations and suggest that a similar set of resistance genes are responsible for resistance to Cry1Ab and Cry1Ac and are selected whichever toxin was used. The possibility of an incompletely dominant trait of resistant to these toxins should be taken into account when considering refuge resistance management strategies.

  8. Three phase voltage model AC-AC frequency-variable inverter controlled by single-chip microcomputer%单片机控制的三相电压型交-交变频器

    Institute of Scientific and Technical Information of China (English)

    王建国

    2001-01-01

    介绍一种单片机控制的三相电压型交-交变频器,论述了交-交变频器的系统组成、控制方案及有关难点问题的解决%This paper introduces a kind of three phase voltage model AC-ACfrequency-variable inverter controlled by single-chip microcomputer control. Construction of the system ,controlling program and solution of some difficult problems are described

  9. A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera.

    Science.gov (United States)

    Chen, Wenbo; Liu, Chenxi; Xiao, Yutao; Zhang, Dandan; Zhang, Yongdong; Li, Xianchun; Tabashnik, Bruce E; Wu, Kongming

    2015-01-01

    Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry) proteins from the bacterium Bacillus thuringiensis (Bt) in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50) of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f) was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

  10. A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera.

    Directory of Open Access Journals (Sweden)

    Wenbo Chen

    Full Text Available Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry proteins from the bacterium Bacillus thuringiensis (Bt in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50 of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

  11. A Coordinated Control for Photovoltaic Generators and Energy Storages in Low-Voltage AC/DC Hybrid Microgrids under Islanded Mode

    Directory of Open Access Journals (Sweden)

    Yao Liu

    2016-08-01

    Full Text Available The increasing penetration of renewable generators can be a significant challenge due to the fluctuation of their power generation. Energy storage (ES units are one solution to improve power supply quality and guarantee system stability. In this paper, a hybrid microgrid is built based on photovoltaic (PV generator and ES; and coordinated control is proposed and developed to achieve power management in a decentralized manner. This control scheme contains three different droop strategies according to characteristics of PV and ES. First, the modified droop control is proposed for PV, which can take full utilization of renewable energy and avoid regulating output active power frequently. Second, to maintain the direct current (DC bus voltage stability, a novel droop control incorporating a constant power band is presented for DC-side ES. Third, a cascade droop control is designed for alternating current (AC-side ES. Thus, the ES lifetime is prolonged. Moreover, interlinking converters (ICs provide a bridge between AC/DC buses in a hybrid microgrid. The power control of IC is enabled when the AC- or DC-side suffer from active power demand shortage. In particular, if the AC microgrid does not satisfy the reactive power demand, IC then acts as a static synchronous compensator (STATCOM. The effectiveness of the proposed strategies is verified by simulations.

  12. A Secondary Voltage Control Method for an AC/DC Coupled Transmission System Based on Model Predictive Control

    DEFF Research Database (Denmark)

    Xu, Fengda; Guo, Qinglai; Sun, Hongbin;

    2015-01-01

    to keep the voltage of the pilot bus tracking its set point considering the DC system’s transmission schedule change. The approach is inspired by model predictive control (MPC) to compensate for predictable voltage change affected by DC side transmission power flow and the potential capacitor switching...

  13. Power sharing algorithm for vector controlled six-phase AC motor with four customary three-phase voltage source inverter drive

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevikumar; Grandi, Gabriele; Blaabjerg, Frede

    2015-01-01

    This paper considered a six-phase (asymmetrical) induction motor, kept 30 phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs) and all four dc sources are deliberately kept isolated......) by nearest three vectors (NTVs) approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/ Simulink-PLECS software) of whole ac drive system by observing the dynamic behaviors in different designed condition. Set...

  14. Six-step Voltage Control of PM Brushless AC Motors under High Speed Flux-weakening Operation for EV/HEV Applications

    Institute of Scientific and Technical Information of China (English)

    诸自强

    2008-01-01

    The torque-speed characteristics of brushless motor having an interior permanent magnet rotor and a sinusoidalback-emf waveform are compared experimentally when it is operated in brushless AC (BLAC) mode and brushless DC(BLDC) modes with both 2-phase, 120° conduction (BLDC-120) and 3-phase,180° conduction (BLDC-180).Particularemphasis is on high-speed,six-step voltage controlled,flux-weakening operation.h is shown that for EV/HEV applications,even for interior PM brushless motors which have sinusoidal back-emf waveforms,in order to achieve maximum torque perampere capability over wide operation speed range,it is advantageous to employ a hybrid operation mode-BLAC operationin the constant torque region and six-step voltage control (BLDC-180 operation, together with current phase control) inthe flux-weakening region.

  15. Improved Direct Deadbeat Voltage Control with an Actively Damped Inductor-Capacitor Plant Model in an Islanded AC Microgrid

    Directory of Open Access Journals (Sweden)

    Jaehong Kim

    2016-11-01

    Full Text Available A direct deadbeat voltage control design method for inverter-based microgrid applications is proposed in this paper. When the inductor-capacitor (LC filter output voltage is directly controlled using voltage source inverters (VSIs, the plant dynamics exhibit second-order resonant characteristics with a load current disturbance. To effectively damp the resonance caused by the output LC filter, an active damping strategy that does not cause additional energy loss is utilized. The proposed direct deadbeat voltage control law is devised from a detailed, actively damped LC plant model. The proposed deadbeat control method enhances voltage control performance owing to its better disturbance rejection capability than the conventional deadbeat or proportional-integral-based control methods. The most important advantage of the proposed deadbeat control method is that it makes the deadbeat control more robust by bringing discrete closed-loop poles closer to the origin. Simulation and experimental results are shown to verify the enhanced voltage control performance and stability of the proposed voltage control method.

  16. Resistivity and AC calorimetry measurements on CeNiGe{sub 2} under pressure

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, A.T. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan)]. E-mail: alex@djebel.mp.es.osaka-u.ac.jp; Muramatsu, T. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Miyake, A. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Kaczorowski, D. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland); Bukowski, Z. [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland); Kagayama, T. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Shimizu, K. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan)

    2007-03-15

    We present resistivity and AC calorimetry measurements of single crystalline CeNiGe{sub 2} under high pressure and low temperature in a diamond anvil cell. CeNiGe{sub 2} is a highly anisotropic, antiferromagnetic Kondo system at ambient pressure, located close to the boundary with non-magnetic systems. It has two ordering temperatures, T{sub N1}=3.9K and T{sub N2}=3.2K, which are suppressed under pressure. Between 0.7 and 1.4GPa only a single transition was identified, with T{sub N} reaching 1.9K by 1.4 GPa. At 1.9GPa two transitions could again be seen by AC calorimetry at 2.0 and 1.3K, accompanied by a qualitative change in the behaviour of the resistivity. The Sommerfeld coefficient showed a maximum of 755mJmol{sup -1}K{sup -2} at 1.4GPa, up from 448mJmol{sup -1}K{sup -2} at close to ambient pressure. The residual resistivity was found to decrease sharply above 1.4GPa after an initial increase with pressure.

  17. Neutral-point voltage control for a three-level DC-AC inverter using equivalent-input-disturbance approach

    Institute of Scientific and Technical Information of China (English)

    Jie ZHANG; Ryuichi YOKOYAMA; Jinhua SHE; Win WU

    2013-01-01

      One problem with a single source three-level inverter is the drafting of its neutral-point voltage. This may occur during transition or when unbalanced loads are connected to the inverter system. Variation of neutral-point voltage may greatly deteriorate the power quality. In this paper, we employ an equivalent-input-disturbance approach to deal with this problem. By adding an extra neutral leg, the control problem of neutral-point voltage is converted to a disturbance rejection problem. This method suppresses the variation of the neutral-point voltage to a low level and reduces the capacity of DC-link capacitors. Simulation results show the effectiveness of the method.

  18. Design of a Solid-State Fast Voltage Compensator for klystron modulators requiring constant AC power consumption

    CERN Document Server

    Aguglia, Davide; Viarouge, Philippe; Cros, Jerome

    2014-01-01

    This paper proposes a novel topological solution for klystron modulators integrating a Fast Voltage Compensator which allows an operation at constant power consumption from the utility grid. This kind of solution is mandatory for the CLIC project under study, which requires several hundreds of synchronously operated klystron modulators for a total pulsed power of 39 GW. The topology is optimized for the challenging CLIC specifications, which require a very precise output voltage flat-top as well as fast rise and fall times (3µs). The Fast Voltage Compensator is integrated in the modulator such that it only has to manage the capacitor charger current and a fraction of the charging voltage. Consequently, its dimensioning power and cost is minimized.

  19. Power Flow Analysis for Low-Voltage AC and DC Microgrids Considering Droop Control and Virtual Impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay Kumar; Savaghebi, Mehdi

    2017-01-01

    adequate power flow studies. In this paper, power flow analyses for both AC and DC microgrids are formulated and implemented. The mathematical models for both types of microgrids considering the concept of virtual impedance are used to be in conformity with the practical control of the distributed...... generators. As a result, calculation accuracy is improved for both AC and DC microgrid power flow analyses, comparing with previous methods without considering virtual impedance. Case studies are conducted to verify the proposed power flow analyses in terms of convergence and accuracy. Investigation...

  20. Distributed voltage control and load sharing for inverter-interfaced microdrid with resistive lines

    DEFF Research Database (Denmark)

    Golsorkhi, Mohammad S.; Lu, D. D C; Shafiee, Q.

    2016-01-01

    method is based upon the practical assumption of resistive network impedance. In this context, a V-I droop mechanism is adopted in the primary control level, where GPS timing is used to synchronize the control agents. A new distributed secondary control method based on consensus protocol is introduced......This paper proposes a new distributed control method for coordination of distributed energy resources (DERs) in low-voltage resistive microgrids. The proposed framework consists of two level structure; primary and secondary control. Unlike the existing distributed control methods, the proposed...

  1. Simultaneous On-State Voltage and Bond-Wire Resistance Monitoring of Silicon Carbide MOSFETs

    Directory of Open Access Journals (Sweden)

    Nick Baker

    2017-03-01

    Full Text Available In fast switching power semiconductors, the use of a fourth terminal to provide the reference potential for the gate signal—known as a kelvin-source terminal—is becoming common. The introduction of this terminal presents opportunities for condition monitoring systems. This article demonstrates how the voltage between the kelvin-source and power-source can be used to specifically monitor bond-wire degradation. Meanwhile, the drain to kelvin-source voltage can be monitored to track defects in the semiconductor die or gate driver. Through an accelerated aging test on 20 A Silicon Carbide Metal-Oxide-Semiconductor-Field-Effect Transistors (MOSFETs, it is shown that there are opposing trends in the evolution of the on-state resistances of both the bond-wires and the MOSFET die. In summary, after 50,000 temperature cycles, the resistance of the bond-wires increased by up to 2 mΩ, while the on-state resistance of the MOSFET dies decreased by approximately 1 mΩ. The conventional failure precursor (monitoring a single forward voltage cannot distinguish between semiconductor die or bond-wire degradation. Therefore, the ability to monitor both these parameters due to the presence of an auxiliary-source terminal can provide more detailed information regarding the aging process of a device.

  2. 大容量发电机出口断路器选择%Circuit Breakers Selection Method for Large-capacity AC High-voltage Generator

    Institute of Scientific and Technical Information of China (English)

    张爽

    2011-01-01

    针对大容量发电机出口断路器的选择问题,依据GB/T 14824-2008、IEEE Std C37.013-1997和IEC 60909-0-2001中的计算方法,并结合发电机出口断路器型式试验报告的有关数据,以某百万千瓦级发电机组为例进行了比较计算,分析计算结果,提出了对发电机出口短路器短路电流开断能力不能采用百分比而应采用绝对值进行校验.%For selecting large-capacity AC high-voltage generator circuit breakers in a large generator system, comparative calculations are conducted for a million kilowatts rated generator following the standards of GB/T 14824-2008, IEEE Std C37.013-1997 and IEC 60909-0-2001. The calculation results and the test reports of generator circuit breakers are analyzed, and a suggestion is hence offered that absolute value of short-circuit current should be used for examining the short-circuit current breaking capacity of an AC high-voltage generator circuit breaker instead of percentage value.

  3. 直接AC/AC变换器输出电压及电流纹波分析%Analysis of Output Voltage and Current Ripple for Direct AC/AC Converter

    Institute of Scientific and Technical Information of China (English)

    文锋; 赵冉; 刘菁

    2009-01-01

    为解决直接AC/AC交换器的输出纹波计算问题,本文建立了以DC/DC变换器结构为基础的六种AC/AC变换器的理想模型.利用这些理想模型,DC/DC变换器的一般分析方法可方便地引入到AC/AC变换器的分析中,然后,论文以Buck型AC/AC变换器为例,给出其电路输出纹波系数的计算公式.为了证明理论分析的正确性,搭建了实验电路,实验结果与理论计算得到了很好的吻合.

  4. PWM的整流器无交流电压传感器控制%Vector Control of PWM Rectifier without AC Voltage sensors

    Institute of Scientific and Technical Information of China (English)

    张宏杰

    2012-01-01

      针对采用虚拟磁链定向控制策略的PWM整流器无交流电压传感器控制中存在的由积分环节带来的一系列问题,将滑模观测器(SMO)应用于估测电网电压角度,利用饱和函数代替传统滑模观测器中的符号函数以削弱系统抖振,并对比分析了两种情况下等效控制信号的频谱图,仿真和实验结果表明,基于滑模观测器的PWM整流器具有良好的动静态响应和输入输出特性,验证了所提出的无交流电压传感器控制策略的有效性和准确性。%  To solve the problems caused by integer which were used in virtual flux oriented control of PWM rec⁃tifier without AC voltage sensors, a sliding mode observer (SMO) was designed to estimate grid voltage angle. This paper analyzes the principle, designs steps of SMO .and uses saturated function instead of symbols function in traditional sliding mode observer to weaken the system chattering. The paper also analyzes the equivalent con⁃trol signal spectrum diagram in the two cases. Simulation and experimental results show that PWM rectifier has a good dynamic/static response and input/output characteristics and verifies the validity and feasibility of the pro⁃posed AC voltage sensorless control strategy.

  5. 550 kV双断口交流滤波器断路器暂态恢复电压仿真%Simulation of Transient Recovery Voltage of 550 kV AC Filter Breaker with Double Breaks

    Institute of Scientific and Technical Information of China (English)

    施健; 罗兵; 傅明利; 厉天威; 曾向君; 贾磊; 张福增

    2016-01-01

    直流换流站安装有不同滤波次数的交流滤波器(AC filter,ACF),ACF断路器频繁操作以满足换流站无功补偿的需要,在开断大容性电流后断口承受交直流混合电压的共同作用,断口直流分压按电阻分布,而断口等效电阻受外界环境的影响,因此断口承受的电压可能会超过其绝缘能力。以国内典型的550 kV瓷柱式双断口小组滤波器断路器为例,利用PSCAD建立暂态恢复电压(TRV)仿真电路模型,对影响断口TRV分布的环境因素进行了仿真,仿真结果显示外界环境因素(如湿度、污秽、干湿不均等)对断口TRV影响较大,在特定环境条件下当断口绝缘电阻下降较大且两断口电阻值差异较大时,断口最大TRV值会接近或超过规范要求值,从而可能造成断口电弧重燃或闪络故障。%AC filters (ACFs)for different harmonics are installed in HVDC stations,they switch on and off very often with circuit breakers for reactive power compensation. ACF breakers bear transient recovery voltages (TRV)comprising AC and DC voltages after switching off large capacitive current,because the DC voltage component is decided and divided by resistance which is influenced by the ambient environment of porcelain breaker external insulation,the TRV may exceed the insulation requirement. Using a typical 550 kV AC filter procelain breaker with two breaks used in HVDC stations as an example,a simulation model of TRV is established based on PSCAD to simulate the influencing factors of TRV. The simulation results show that the ambient environment,such as humidity, dirt and dry zone,can seriously affect the TRV of breaks. With specific ambient environment conditions,when the break resistance decreases and the diffence between the two break resistances is large,the maximum break TRV may approach or even exceed the theshhold value,which will result in breaker restrike or flashover.

  6. The exenatide analogue AC3174 attenuates hypertension, insulin resistance, and renal dysfunction in Dahl salt-sensitive rats

    Directory of Open Access Journals (Sweden)

    Fernandez Rayne

    2010-08-01

    Full Text Available Abstract Background Activation of glucagon-like peptide-1 (GLP-1 receptors improves insulin sensitivity and induces vasodilatation and diuresis. AC3174 is a peptide analogue with pharmacologic properties similar to the GLP-1 receptor agonist, exenatide. Hypothetically, chronic AC3174 treatment could attenuate salt-induced hypertension, cardiac morbidity, insulin resistance, and renal dysfunction in Dahl salt-sensitive (DSS rats. Methods DSS rats were fed low salt (LS, 0.3% NaCl or high salt (HS, 8% NaCl diets. HS rats were treated with vehicle, AC3174 (1.7 pmol/kg/min, or GLP-1 (25 pmol/kg/min for 4 weeks via subcutaneous infusion. Other HS rats received captopril (150 mg/kg/day or AC3174 plus captopril. Results HS rat survival was improved by all treatments except GLP-1. Systolic blood pressure (SBP was lower in LS rats and in GLP-1, AC3174, captopril, or AC3174 plus captopril HS rats than in vehicle HS rats (p Conclusions Thus, AC3174 had antihypertensive, cardioprotective, insulin-sensitizing, and renoprotective effects in the DSS hypertensive rat model. Furthermore, AC3174 improved animal survival, an effect not observed with GLP-1.

  7. High-voltage (> 1 kV) SiC Schottky barrier diodes with low on-resistance

    Energy Technology Data Exchange (ETDEWEB)

    Kimoto, Tsunenobu; Urushidani, Tatsuo; Kobayashi, Sota; Matsunami, Hiroyuki (Kyoto Univ. (Japan). Dept. of Electrical Engineering)

    1993-12-01

    Au/6H-SiC Schottky barrier diodes with high blocking voltages were successfully fabricated using layers grown by step-controlled epitaxy. A breakdown voltage over 1,100 V could be achieved, which is the highest ever reported for silicon carbide (SiC) Schottky barrier diodes. These high-voltage SiC rectifiers had specific on-resistances lower than the theoretical limits of Si rectifiers by more than one order of magnitude. The specific on-resistance increased with temperature according to T[sup 2.0] dependence. The diodes showed good characteristics at temperature as high as 400 C.

  8. Power sharing algorithm for vector controlled six-phase AC motor with four customary three-phase voltage source inverter drive

    Directory of Open Access Journals (Sweden)

    Sanjeevikumar Padmanaban

    2015-09-01

    Full Text Available This paper considered a six-phase (asymmetrical induction motor, kept 30° phase displacement between two set of three-phase open-end stator windings configuration. The drive system consists of four classical three-phase voltage inverters (VSIs and all four dc sources are deliberately kept isolated. Therefore, zero-sequence/homopolar current components cannot flow. The original and effective power sharing algorithm is proposed in this paper with three variables (degree of freedom based on synchronous field oriented control (FOC. A standard three-level space vector pulse width modulation (SVPWM by nearest three vectors (NTVs approach is adopted to regulate each couple of VSIs. The proposed power sharing algorithm is verified by complete numerical simulation modeling (Matlab/Simulink-PLECS software of whole ac drive system by observing the dynamic behaviors in different designed condition. Set of results are provided in this paper, which confirms a good agreement with theoretical development.

  9. Cable Crosstalk Suppression with Two-Wire Voltage Feedback Method for Resistive Sensor Array.

    Science.gov (United States)

    Wu, Jianfeng; He, Shangshang; Li, Jianqing; Song, Aiguo

    2016-01-01

    Using a long, flexible test cable connected with a one-wire voltage feedback circuit, a resistive tactile sensor in a shared row-column fashion exhibited flexibility in robotic operations but suffered from crosstalk caused by the connected cable due to its wire resistances and its contacted resistances. Firstly, we designed a new non-scanned driving-electrode (VF-NSDE) circuit using two wires for every row line and every column line to reduce the crosstalk caused by the connected cables in the circuit. Then, an equivalent resistance expression of the element being tested (EBT) for the two-wire VF-NSDE circuit was analytically derived. Following this, the one-wire VF-NSDE circuit and the two-wire VF-NSDE circuit were evaluated by simulation experiments. Finally, positive features of the proposed method were verified with the experiments of a two-wire VF-NSDE prototype circuit. The experiment results show that the two-wire VF-NSDE circuit can greatly reduce the crosstalk error caused by the cables in the 2-D networked resistive sensor array.

  10. 移动基站交流稳压技术探讨%Discussion on the AC Voltage Stabilization in the Mobile Stations

    Institute of Scientific and Technical Information of China (English)

    黄坤材

    2001-01-01

    Aiming at the national bad status of AC power to the telecom power, the paper dis cusses some issues which should be careful when the mobile base stations select the AC voltage stabilizer, introduces and analysises in detail the performance of various national made stabilizer,such as, mechanic adjustable compensation stabilizer, parameter stabilizer, inductive stabilizer,silicon-control compensation stabilizer. At last, it presents the proposal on the selection of the stabilizer to the mobile base stations.%针对我国通信电源交流供电状况不良的现状,论述了移动通信基站交流稳压器选型应注意的几个问题,详细介绍了国内生产的机械调压补偿式稳压器、参数稳压器、感应式稳压器、可控硅补偿式稳压器等产品性能,并进行了比较。最后提出了移动通信基站交流稳压器选型的建议。

  11. Study of the electric field and wall voltage in a high pressure ac-PDP cell by laser induced fluorescence spectroscopy

    Institute of Scientific and Technical Information of China (English)

    Zhou Yan; K. W. Whang; J. H. Yang; D. C. Jeong; C.H.Ha; Y.W. Choi

    2004-01-01

    The electric field in a surface discharge type ac-PDP cell with He or He/Xe(0.1%) mixture has been measured over a wide range of pressure (5 50kP1 using laser induced fluorescence detection. The wall voltage was estimated from the measured electric field. The Stark manifolds of triplet atomic helium Rydberg state (2s3S) with principal quantum numbers (n=8 and 9) have been used to measure the electric field, as the lifetime of 2s3S is longer than the single atomic helium Rydberg state (2s1S) in high pressure discharge. Comparison of the Stark manifolds between the n=9 and n=8shows that the measurement accuracy of electric field can be increased by 10%. The maximum electric field strength during discharge and the wall voltage at the end of pulse decreases with the increase of pressure. The comparison of He and He/Xe(0.1%) discharge at 13kPa showed that He/Xe gas mixture discharge can accumulate more wall charge on MgO surface and the electric field was somewhat higher than those of pure helium discharge during pulse off period under the same discharge conditions.

  12. Effects of cathodic voltages on structure and wear resistance of plasma electrolytic oxidation coatings formed on aluminium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qingbiao [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); School of Science, Lanzhou University of Technology, Lanzhou 730050 (China); Liang, Jun, E-mail: jliang@licp.cas.cn [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Liu, Baixing; Peng, Zhenjun [State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); Wang, Qing [School of Science, Lanzhou University of Technology, Lanzhou 730050 (China)

    2014-04-01

    Highlights: • The PEO coating growth rate increased with the cathodic voltage increasing. • Higher cathodic voltage resulted in more compact coating structure. • The compact structure led to low surface roughness and high wear resistance. - Abstract: Plasma electrolytic oxidation (PEO) coatings were prepared on aluminium alloy using pulsed bipolar power supply at constant anodic voltage and different cathodic voltages. The samples were prepared to attain the same coating thickness by adjusting the processing time. The scanning electron microscope (SEM), energy dispersive spectrometer (EDS), X-ray diffraction (XRD) and tribometer were employed to investigate the microstructure, element content, phase composition and wear resistance of the coatings respectively. It was found that the coating growth rate enhanced obviously and the coatings exhibited a more compact structure with thicker inner layer and lower surface roughness when the cathodic voltage increased. The coatings were mainly composed of crystalline γ-Al{sub 2}O{sub 3} and amorphous silicate oxides and their relative content changed with the cathodic voltage. The wear resistance of the coatings improved significantly with the increase of cathodic voltage.

  13. Performance Characteristics ofAC Contactor During Voltage Sag%晃电故障下交流接触器的工作特性分析

    Institute of Scientific and Technical Information of China (English)

    林抒毅; 许志红

    2011-01-01

    电磁式交流接触器是一种应用广泛的低压电器产品,当晃电故障发生时,交流接触器可能因为不稳定电压而频繁接通或分断,对系统造成很大的影响。论文以CJ20.63A交流接触器为研究对象,建立考虑触头运动情况的电磁机构吸合过程、吸持阶段以及释放过程的磁路动态计算方程,并通过实验验证了模型的正确性。针对不同的合闸相角和工作状态进行仿真,分析了发生晃电故障时电压下降幅度、晃电故障持续时间、晃电故障发生时刻及电压相角变化对接触器工作特性的影响。结果表明,吸合阶段的晃电影响与吸合时问有直接关系,吸合以后的晃电故障影响存在临界%Electromagnetic contactor is a kind of widely used electric product. When the voltage drops suddenly, the contactor will be open or closed frequently, and the circuit will be influenced seriously. Based on the research of CJ20-63A contactor dynamic equations were established during closing, cIosed and opening processes; the movement process of the moving contact and the bounce of the contacts were considered at the meantime. The experimental data shows the model is correct. Simulations were carried out with respect to different working states and various closing phase angles. Influences of the range, duration and occurrence time of voltage drop, and the variation of voltage phases on performance characteristics of contactors were analyzed; the result indicates that the influences of voltage sag on the contactor are related to the closing time directly in the closing process; and a critical time value should be considered after the contactor is closed. This research provides the basic for the further study on the intelligent AC contactor with anti-voltage sag.

  14. Core-suppressed AC loss and strand-moderated contact resistance in a Nb3Sn Rutherford cable

    NARCIS (Netherlands)

    Sumption, M.D.; Collings, E.W.; Scanlan, R.M.; Nijhuis, A.; Kate, ten H.H.J.

    1999-01-01

    Calorimetric measurements of AC loss and hence interstrand contact resistance (ICR), have been performed on two types of Rutherford cable wound with unplated Nb3Sn strand. One of the cable types was furnished with a thin core of AISI 316L stainless steel and the other was left uncored. The cables we

  15. Toxicity and binding analyses of Bacillus thuringiensis toxin Vip3A in Cry1Ac-resistant and-susceptible strains of Helicoverpa armigera (Hübner)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Qian; CHEN Li-zhen; LU Qiong; ZHANG Yan; LIANG Ge-mei

    2015-01-01

    The Bacil us thuringiensis vegetative insecticidal protein, Vip3A, represents a new family of Bt toxin and is currently ap-plied to commercial transgenic cotton. To determine whether the Cry1Ac-resistant Helicoverpa armigera is cross-resistant to Vip3Aa protein, insecticidal activities, proteolytic activations and binding properties of Vip3Aa toxin were investigated using Cry1Ac-susceptible (96S) and Cry1Ac-resistant H. armigera strain (Cry1Ac-R). The toxicity of Vip3Aa in Cry1Ac-R slightly reduced compared with 96S, the resistance ratio was only 1.7-fold. The digestion rate of ful-length Vip3Aa by gut juice extracts from 96S was little faster than that from Cry1Ac-R. Surface plasmon resonance (SPR) showed there was no signiifcant difference between the binding afifnity of Vip3Aa and BBMVs between 96S and Cry1Ac-R strains, and there was no signiifcant competitive binding between Vip3Aa and Cry1Ac in susceptible or resistant strains. So there had little cross-resistance between Vip3Aa and Cry1Ac,Vip3A+Cry proteins maybe the suitable pyramid strategy to control H. armigera in China in the future.

  16. Identification of problems when using long high voltage AC cable in transmission system II: Resonance & Harmonic resonance

    DEFF Research Database (Denmark)

    Rahimi, Saeed; Wiechowski, W.; Randrup, M.;

    2008-01-01

    cable in transmission system. The objective of this paper and the companion paper is to address the most important problems expected in transmission system with relatively larger share of long HV underground cables. The end goal will be a guideline to special solutions and precautions to avoid dangerous...... over voltage problems and also resonance problems in a transmission network with future increased share of cables. Two major categories of problems are switching transient and resonance problems. In each category of the possible problems, first some theoretical background is provided...... and then the problem and countermeasures are discussed. In this paper most important resonance problems are addressed and discussed. Three main categories of resonance problems are: Near Resonance, Harmonic resonance and Ferroresonance....

  17. Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics

    Energy Technology Data Exchange (ETDEWEB)

    Ming, Miao Yi [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Jiang, Xiaohong, E-mail: jxh0668@sina.com [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Piliptsou, D.G., E-mail: pdg_@mail.ru [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Zhuang, Yuzhao; Rogachev, A.V.; Rudenkov, A.S. [International Chinese-Belarusian scientific laboratory on vacuum-plasma technology, Nanjing University of Science and Technology, Nanjing 210094 (China); Francisk Skorina Gomel State University, Gomel 246019 (Belarus); Balmakou, A. [Faculty of Material Science and Technology, Slovak University of Technology, Trnava 91724 (Slovakia)

    2016-08-30

    Highlights: • Influence of the chromium interlayer on the structure and mechanical properties of a-C:Cr films. • Residual stress and wear of a-C:Cr and Cr/a-C varies due to their phase and surface morphology. • Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics. - Abstract: To improve structural, mechanical and chemical properties of diamond-like carbon films, we developed amorphous carbon chromium-modified composite films fabricated by means of cathode magnetic filtered arc deposition. The properties were analyzed by Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy for the purpose of the structure characterization, elemental analysis and topology examination. Moreover, we also assessed residual stress, the coefficient of friction, hardness, the elastic modulus and corrosion parameters through X-ray double-crystal surface profilometry, tribo-testing, nanoindenter-testing, as well as contact angle measurements and potentiodynamic polarization analysis. As a result of a comparative analysis, we revealed a substantial improvement in the characteristics of developed composite films in comparison with amorphous carbon films. For example, Cr-modification is resulted, in greater integrated performance, toughness and corrosion resistance; the residual stress was reduced substantially.

  18. Study of imbalanced internal resistance on drop voltage of LiFePO4 battery system connected in parallel

    Science.gov (United States)

    Adie Perdana, Fengky; Supriyanto, Agus; Purwanto, Agus; Jamaluddin, Anif

    2017-01-01

    The purpose of this research focuses on the effect of imbalanced internal resistance for the drop voltage of LiFePO4 18650 battery system connected in parallel. The battery pack has been assembled consist of two cell battery LiFePO4 18650 that has difference combination of internal resistance. Battery pack was tested with 1/C constant current charging, 3,65V per group sel, 3,65V constant voltage charging, 5 minutes of rest time between charge and discharge process, 1/2C Constant current discharge until 2,2V, 26 cycle of measurement test, and 4320 minutes rest time after the last charge cycle. We can conclude that the difference combination of internal resistance on the battery pack seriously influence the drop voltage of a battery. Theoretical and experimental result show that the imbalance of internal resistance during cycling are mainly responsible for the drop voltage of LiFePO4 parallel batteries. It is thus a good way to avoid drop voltage fade of parallel battery system by suppressing variations of internal resistance.

  19. Dynamic modelling and robust current control of wind-turbine driven DFIG during external AC voltage dip

    Institute of Scientific and Technical Information of China (English)

    HU Jia-bing; HE Yi-kang

    2006-01-01

    Doubly-FedInduction Generator (DFIG), with vector control applied, is widely used in Variable-Speed ConstantFrequency (VSCF) windenergy generation system and shows good performance in maximum wind energy capture. But in two traditional vector control schemes, the equivalent stator magnetizing current is considered invariant in order to simplify the rotor current inner-loop controller. The two schemes can perform very well when the grid is in normal condition. However, when grid disturbance such as grid voltage dip or swell fault occurs, the control performance worsens, the rotor over current occurs and the Fault Ride-Through (FRT) capability of the DFIG wind energy generation system gets seriously deteriorated. An accurate DFIG model was used to deeply investigate the deficiency of the traditional vector control. The improved control schemes of two typical traditional vector control schemes used in DFIG were proposed, and simulation study of the proposed and traditional control schemes, with robust rotor current control using Internal Model Control (IMC) method, was carried out. The validity of the proposed modified schemes to control the rotor current and to improve the FRT capability of the DFIG wind energy generation system was proved by the comparison study.

  20. Development of Electrostatic Actuator, which enables the Stable Contact Resistance, Driven at Low Voltage

    Science.gov (United States)

    Masuda, Takahiro; Seki, Tomonori; Miyaji, Takaaki; Sato, Fumihiko

    The switches play an important role in making the multifunctional radio communication circuit and therefore, the high-performance microminiaturized high-frequency switches are urgently expected. RF-MEMS switch with mechanical switching structure is hoped to improve both high-frequency signal loss and isolation quality simultaneously and to provide better linearity on the performance and compatibility to silicon-based circuit elements. But considering the applications, such as cellular phone and wireless-LAN, lower driving voltage and smaller switch dimensions are required. In order to solve these requirements, a novel electrostatic actuator with a unique structure of movable electrodes which enables the stable contact resistance is developed for RF-MEMS switches. This actuator has slits between the movable electrodes and the restoring spring. The electrostatic actuator with a movable electrode area of 0.5mm2 was driven at low voltage of 9-11V. And no defect due to restoration shortage is observed during switching test up to 400million cycles. In this paper, the results of mechanical design of the electrostatic actuator, the simulation, the experiments, and the reliability test are described

  1. High Susceptibility to Cry1Ac and Low Resistance Allele Frequency Reduce the Risk of Resistance of Helicoverpa armigera to Bt Soybean in Brazil

    Science.gov (United States)

    Bacalhau, Fabiana B.; Amado, Douglas; Carvalho, Renato A.; Martinelli, Samuel; Head, Graham P.; Omoto, Celso

    2016-01-01

    The Old World bollworm, Helicoverpa armigera (Hübner), was recently introduced into Brazil, where it has caused extensive damage to cotton and soybean crops. MON 87701 × MON 89788 soybean, which expresses the Bt protein Cry1Ac, was recently deployed in Brazil, providing high levels of control against H. armigera. To assess the risk of resistance to the Cry1Ac protein expressed by MON 87701 × MON 89788 soybean in Brazil, we conducted studies to evaluate the baseline susceptibility of H. armigera to Cry1Ac, in planta efficacy including the assessment of the high-dose criterion, and the initial resistance allele frequency based on an F2 screen. The mean Cry1Ac lethal concentration (LC50) ranged from 0.11 to 1.82 μg·mL−1 of diet among all H. armigera field populations collected from crop seasons 2013/14 to 2014/15, which indicated about 16.5-fold variation. MON 87701 × MON 89788 soybean exhibited a high level of efficacy against H. armigera and most likely met the high dose criterion against this target species in leaf tissue dilution bioassays up to 50 times. A total of 212 F2 family lines of H. armigera were established from field collections sampled from seven locations across Brazil and were screened for the presence of MON 87701 × MON 89788 soybean resistance alleles. None of the 212 families survived on MON 87701 × MON 89788 soybean leaf tissue (estimated allele frequency = 0.0011). The responses of H. armigera to Cry1Ac protein, high susceptibility to MON 87701 × MON 89788 soybean, and low frequency of resistance alleles across the main soybean-producing regions support the assumptions of a high-dose/refuge strategy. However, maintenance of reasonable compliance with the refuge recommendation will be essential to delay the evolution of resistance in H. armigera to MON 87701 × MON 89788 soybean in Brazil. PMID:27532632

  2. Analytical models of on-resistance and breakdown voltage for 4H-SiC floating junction Schottky barrier diodes

    Science.gov (United States)

    Yuan, Hao; Tang, Xiaoyan; Song, Qingwen; Zhang, Yimen; Zhang, Yuming; Yang, Fei; Niu, Yingxi

    2015-01-01

    The analytical models of on-resistance and reverse breakdown voltage for 4H-SiC floating junction SBD are presented with the analysis of the transport path of the carriers and electric field distribution in the drift region. The calculation results from the analytical models well agree with the simulation results. The effects of the key structure parameters on specific on-resistance and breakdown voltage are described respectively by analytical models. Moreover, the relationship between BFOM and parameters of floating junction are investigated. It is proved that the analytical models are more convenient for the design of the floating junction SBDs.

  3. Similar genetic basis of resistance to Bt toxin Cry1Ac in Boll-selected and diet-selected strains of pink bollworm.

    Directory of Open Access Journals (Sweden)

    Jeffrey A Fabrick

    Full Text Available Genetically engineered cotton and corn plants producing insecticidal Bacillus thuringiensis (Bt toxins kill some key insect pests. Yet, evolution of resistance by pests threatens long-term insect control by these transgenic Bt crops. We compared the genetic basis of resistance to Bt toxin Cry1Ac in two independently derived, laboratory-selected strains of a major cotton pest, the pink bollworm (Pectinophora gossypiella [Saunders]. The Arizona pooled resistant strain (AZP-R was started with pink bollworm from 10 field populations and selected with Cry1Ac in diet. The Bt4R resistant strain was started with a long-term susceptible laboratory strain and selected first with Bt cotton bolls and later with Cry1Ac in diet. Previous work showed that AZP-R had three recessive mutations (r1, r2, and r3 in the pink bollworm cadherin gene (PgCad1 linked with resistance to Cry1Ac and Bt cotton producing Cry1Ac. Here we report that inheritance of resistance to a diagnostic concentration of Cry1Ac was recessive in Bt4R. In interstrain complementation tests for allelism, F(1 progeny from crosses between AZP-R and Bt4R were resistant to Cry1Ac, indicating a shared resistance locus in the two strains. Molecular analysis of the Bt4R cadherin gene identified a novel 15-bp deletion (r4 predicted to cause the loss of five amino acids upstream of the Cry1Ac-binding region of the cadherin protein. Four recessive mutations in PgCad1 are now implicated in resistance in five different strains, showing that mutations in cadherin are the primary mechanism of resistance to Cry1Ac in laboratory-selected strains of pink bollworm from Arizona.

  4. Similar genetic basis of resistance to Bt toxin Cry1Ac in Boll-selected and diet-selected strains of pink bollworm.

    Science.gov (United States)

    Fabrick, Jeffrey A; Tabashnik, Bruce E

    2012-01-01

    Genetically engineered cotton and corn plants producing insecticidal Bacillus thuringiensis (Bt) toxins kill some key insect pests. Yet, evolution of resistance by pests threatens long-term insect control by these transgenic Bt crops. We compared the genetic basis of resistance to Bt toxin Cry1Ac in two independently derived, laboratory-selected strains of a major cotton pest, the pink bollworm (Pectinophora gossypiella [Saunders]). The Arizona pooled resistant strain (AZP-R) was started with pink bollworm from 10 field populations and selected with Cry1Ac in diet. The Bt4R resistant strain was started with a long-term susceptible laboratory strain and selected first with Bt cotton bolls and later with Cry1Ac in diet. Previous work showed that AZP-R had three recessive mutations (r1, r2, and r3) in the pink bollworm cadherin gene (PgCad1) linked with resistance to Cry1Ac and Bt cotton producing Cry1Ac. Here we report that inheritance of resistance to a diagnostic concentration of Cry1Ac was recessive in Bt4R. In interstrain complementation tests for allelism, F(1) progeny from crosses between AZP-R and Bt4R were resistant to Cry1Ac, indicating a shared resistance locus in the two strains. Molecular analysis of the Bt4R cadherin gene identified a novel 15-bp deletion (r4) predicted to cause the loss of five amino acids upstream of the Cry1Ac-binding region of the cadherin protein. Four recessive mutations in PgCad1 are now implicated in resistance in five different strains, showing that mutations in cadherin are the primary mechanism of resistance to Cry1Ac in laboratory-selected strains of pink bollworm from Arizona.

  5. Embedded Artificial Neuval Network-Based Real-Time Half-Wave Dynamic Resistance Estimation during the A.C. Resistance Spot Welding Process

    Directory of Open Access Journals (Sweden)

    Liang Gong

    2013-01-01

    Full Text Available Online monitoring of the instantaneous resistance variation during the A.C. resistance spot welding is of paramount importance for the weld quality control. On the basis of the welding transformer circuit model, a new method is proposed to measure the transformer primary-side signal for estimating the secondary-side resistance in each 1/4 cycle. The tailored computing system ensures that the measuring method possesses a real-time computational capacity with satisfying accuracy. Since the dynamic resistance cannot be represented via an explicit function with respect to measurable parameters from the primary side of the welding transformer, an offline trained embedded artificial neural network (ANN successfully realizes the real-time implicit function calculation or estimation. A DSP-based resistance spot welding monitoring system is developed to perform ANN computation. Experimental results indicate that the proposed method is applicable for measuring the dynamic resistance in single-phase, half-wave controlled rectifier circuits.

  6. Frequency of alleles conferring resistance to the Bt toxins Cry1Ac and Cry2Ab in Australian populations of Helicoverpa armigera (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Mahon, R J; Olsen, K M; Downes, S; Addison, S

    2007-12-01

    Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) is an important lepidopteran pest of cotton (Gossypium spp.) in Australia and the Old World. From 2002, F2 screens were used to examine the frequency of resistance alleles in Australian populations of H. armigera to Bacillus thuringiensis (Bt) CrylAc and Cry2Ab, the two insecticidal proteins present in the transgenic cotton Bollgard II. At that time, Ingard (expressing Cry1Ac) cotton had been grown in Australia for seven seasons, and Bollgard II was about to be commercially released. The principal objective of our study was to determine whether sustained exposure caused an elevated frequency of alleles conferring resistance to Cry1Ac in a species with a track record of evolving resistance to conventional insecticides. No major alleles conferring resistance to Cry1Ac were found. The frequency of resistance alleles for Cry1Ac was <0.0003, with a 95% credibility interval between 0 and 0.0009. In contrast, alleles conferring resistance to Cry2Ab were found at a frequency of 0.0033 (0.0017, 0.0055). The first isolation of this allele was found before the widespread deployment of Bollgard II. For both toxins the experiment-wise detection probability was 94.4%. Our results suggest that alleles conferring resistance to Cry1Ac are rare and that a relatively high baseline frequency of alleles conferring resistance to Cry2Ab existed before the introduction of Bt cotton containing this toxin.

  7. Measurement of CuInSe{sub 2} solar cell AC parameters

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, M.P.; Nagaraju, J. [Solar Energy and Thermodynamics Laboratory, Department of Instrumentation, Indian Institute of Science, Bangalore 560 012 (India)

    2005-01-31

    The AC parameters (cell capacitance and cell resistance) of Copper Indium Diselenide (CuInSe{sub 2}) solar cell are measured using time-domain technique. The cell capacitance is calculated from the open circuit voltage decay (OCVD) and cell resistance with solar cell I-V characteristics measured in dark. The solar cell exhibits high parallel resistance and low parallel capacitance. The doping concentration and built in voltage are derived from the 1/C{sub P}{sup 2} versus bias voltage graph. The built-in voltage of the solar cell shows good agreement with measurements published in the literature.

  8. An AC Resistance Optimization Method Applicable for Inductor and Transformer Windings with Full Layers and Partial Layers

    DEFF Research Database (Denmark)

    Shen, Zhan; Li, Zhiguang; Jin, Long

    2017-01-01

    This paper proposes an ac resistance optimization method applicable for both inductor and transformer windings with full layers and partial layers. The proposed method treats the number of layers of the windings as a design variable instead of as a predefined parameter, compared to existing methods...... resistance of windings with partial layers is proposed. The developed analytical equation is verified by both Finite Element Method (FEM) simulations and experimental results from two transformer prototypes. A case study of a transformer design with partial layer windings for a LCC resonant circuit...

  9. Voltage amplification of thermopower waves via current crowding at high resistances in self-propagating combustion waves

    Science.gov (United States)

    Yeo, Taehan; Hwang, Hayoung; Cho, Yonghwan; Shin, Dongjoon; Choi, Wonjoon

    2015-07-01

    Combustion wave propagation in micro/nanostructured materials generates a chemical-thermal-electrical energy conversion, which enables the creation of an unusual source of electrical energy, called a thermopower wave. In this paper, we report that high electrical resistance regimes would significantly amplify the output voltage of thermopower waves, because the current crowding creates a narrow path for charge carrier transport. We show that the structurally defective regions in the hybrid composites of chemical fuels and carbon nanotube (CNT) arrays determine both the resistance levels of the hybrid composites and the corresponding output voltage of thermopower waves. A sudden acceleration of the crowded charges would be induced by the moving reaction front of the combustion wave when the supplied driving force overcomes the potential barrier to cause charge carrier transport over the defective region. This property is investigated experimentally for the locally manipulated defective areas using diverse methods. In this study, thermopower waves in CNT-based hybrid composites are able to control the peak voltages in the range of 10-1000 mV by manipulating the resistance from 10 Ω to 100 kΩ. This controllable voltage generation from thermopower waves may enable applications using the combustion waves in micro/nanostructured materials and better understanding of the underlying physics.

  10. Implementation of an active instructional design for teaching the concepts of current, voltage and resistance

    Science.gov (United States)

    Orlaineta-Agüero, S.; Del Sol-Fernández, S.; Sánchez-Guzmán, D.; García-Salcedo, R.

    2017-01-01

    In the present work we show the implementation of a learning sequence based on an active learning methodology for teaching Physics, this proposal tends to promote a better learning in high school students with the use of a comic book and it combines the use of different low-cost experimental activities for teaching the electrical concepts of Current, Resistance and Voltage. We consider that this kind of strategy can be easily extrapolated to higher-education levels like Engineering-college/university level and other disciplines of Science. To evaluate this proposal, we used some conceptual questions from the Electric Circuits Concept Evaluation survey developed by Sokoloff and the results from this survey was analysed with the Normalized Conceptual Gain proposed by Hake and the Concentration Factor that was proposed by Bao and Redish, to identify the effectiveness of the methodology and the models that the students presented after and before the instruction, respectively. We found that this methodology was more effective than only the implementation of traditional lectures, we consider that these results cannot be generalized but gave us the opportunity to view many important approaches in Physics Education; finally, we will continue to apply the same experiment with more students, in the same and upper levels of education, to confirm and validate the effectiveness of this methodology proposal.

  11. 750 kV断路器现场交流耐压试验系统研究与应用%Site AC Voltage Withstand Test System Study and Application of 750 kV Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    温定筠; 乔立凤; 江峰; 王成生; 孙亚明; 吕景顺

    2013-01-01

      介绍了750 kV断路器现场交流耐压试验的标准和时序,分析了基于串联谐振原理的试验方法及试验系统中各设备的具体参数。在此基础上配置出成套的750 kV断路器现场交流耐压试验系统,通过实例成功完成了750 kV断路器主回路及断口的交流耐压试验。%  Introduction was made to the standard and time sequence of site AC voltage withstand test of 750 kV circuit breakers. Analysis was made to the test methods based on serial resonance principle and actual parameters of different equipment in test system. On the basis of this, the site AC voltage withstand test system of a set of 750 kV circuit breakers was disposed. The actual example shows that the AC voltage withstand test for the main circuit and breaking outlet of 750 kV circuit breakers could be completed successfully.

  12. KEY COMPARISONS: Final report: SIM regional comparison of ac-dc voltage transfer difference (SIM.EM.K6a, SIM.EM-K9 and SIM.EM-K11)

    Science.gov (United States)

    Campos, Sara; Filipski, Piotr; Izquierdo, Daniel; Afonso, Edson; Landim, Régis P.; Di Lillo, Lucas; Lipe, Thomas

    2009-01-01

    Three comparisons of ac-dc voltage transfer difference held from January to December 2004 are reported. Six NMIs in the SIM region took part: NRC (Canada), NIST (United States of America), CENAM (Mexico), INTI (Argentina), UTE (Uruguay) and INMETRO (Brazil). The comparisons were proposed to assess the measurement capabilities in ac-dc voltage transfer difference of the NMIs in the SIM region. The test points were selected to link the results with the equivalent CCEM Key Comparisons, through three NMIs participating in both SIM and CCEM key comparisons. Additionally, a SIM.EM-Supplementary comparison was proposed, in support of the SIM NMIs' power/energy meter calibration capabilities. One technical protocol and one travelling standard were used, to economize on time and resources. The report shows the degree of equivalence in the SIM region and also the degree of equivalence with the corresponding CCEM reference value. The results of all participants support the values and uncertainties of the applicable CMC entries for ac-dc voltage transfer difference in the Key Comparison Database held at the BIPM. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

  13. Measurement of AC and DC Insulation Leakage in Platinum Resistance Thermometers up to 960 °C

    Science.gov (United States)

    García, C.; del Campo, D.; Raso, F.

    2011-08-01

    It is well known that insulation leakage at high temperatures can be one of the major contributions to uncertainties in measured temperatures above 600 °C. On the one hand, this insulation leakage shunts the sensor resistor leading to systematic errors in the measured temperatures, which are, in principle, characteristics of each thermometer. On the other hand, at high temperatures, degradation of the insulation materials used in the furnaces enhances the decrease of the insulation impedance between the thermometer and the furnace which also causes a systematic temperature measurement error. Two high-temperature standard platinum resistance thermometers have been used to measure these effects in different heat-pipe and three-zone furnaces. One of them was open-circuited by cutting the sensing element end allowing the measurement of the resistance between the two pairs of current-potential leads. Two different setups were used to measure the AC and DC insulation resistances lead-to-lead and thermometer-to-furnace. The first one was a teraohmeter with a high value standard resistor in parallel with the leakage resistance to be measured and the other one an LCR meter to perform the AC measurements at different frequencies. In this article, results for both methods are presented.

  14. Efficacy of genetically modified Bt toxins alone and in combinations against pink bollworm resistant to Cry1Ac and Cry2Ab.

    Directory of Open Access Journals (Sweden)

    Bruce E Tabashnik

    Full Text Available Evolution of resistance in pests threatens the long-term efficacy of insecticidal proteins from Bacillus thuringiensis (Bt used in sprays and transgenic crops. Previous work showed that genetically modified Bt toxins Cry1AbMod and Cry1AcMod effectively countered resistance to native Bt toxins Cry1Ab and Cry1Ac in some pests, including pink bollworm (Pectinophora gossypiella. Here we report that Cry1AbMod and Cry1AcMod were also effective against a laboratory-selected strain of pink bollworm resistant to Cry2Ab as well as to Cry1Ab and Cry1Ac. Resistance ratios based on the concentration of toxin killing 50% of larvae for the resistant strain relative to a susceptible strain were 210 for Cry2Ab, 270 for Cry1Ab, and 310 for Cry1Ac, but only 1.6 for Cry1AbMod and 2.1 for Cry1AcMod. To evaluate the interactions among toxins, we tested combinations of Cry1AbMod, Cry1Ac, and Cry2Ab. For both the resistant and susceptible strains, the net results across all concentrations tested showed slight but significant synergism between Cry1AbMod and Cry2Ab, whereas the other combinations of toxins did not show consistent synergism or antagonism. The results suggest that the modified toxins might be useful for controlling populations of pink bollworm resistant to Cry1Ac, Cry2Ab, or both.

  15. A reference voltage in capacitor-resister hybrid SAR ADC for front-end readout system of CZT detector

    Science.gov (United States)

    Wei, Liu; Tingcun, Wei; Bo, Li; Lifeng, Yang; Yongcai, Hu

    2016-01-01

    An on-chip reference voltage has been designed in capacitor-resister hybrid SAR ADC for CZT detector with the TSMC 0.35 μm 2P4M CMOS process. The voltage reference has a dynamic load since using variable capacitors and resistances, which need a large driving ability to deal with the current related to the time and sampling rate. Most of the previous articles about the reference for ADC present only the bandgap part for a low temperature coefficient and high PSRR. However, it is not enough and overall, it needs to consider the output driving ability. The proposed voltage reference is realized by the band-gap reference, voltage generator and output buffer. Apart from a low temperature coefficient and high PSRR, it has the features of a large driving ability and low power consumption. What is more, for CZT detectors application in space, a radiation-hardened design has been considered. The measurement results show that the output reference voltage of the buffer is 4.096 V. When the temperature varied from 0 to 80 °C, the temperature coefficient is 12.2 ppm/°C. The PSRR was -70 dB @ 100 kHz. The drive current of the reference can reach up to 10 mA. The area of the voltage reference in the SAR ADC chip is only 449 × 614 μm2. The total power consumption is only 1.092 mW. Project supported by the National Key Scientific Instrument and Equipment Development Project (No. 2011YQ040082), the National Natural Science Foundation of China (No. 61376034), and the Shaanxi Province Science and Technology Innovation Project (No. 2015KTZDGY03-03).

  16. Effects of increase extent of voltage on wear and corrosion resistance of micro-arc oxidation coatings on AZ91D alloy

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The effects of increase extent of voltage on the wear resistance and corrosion resistance of micro-arc oxidation(MAO)coatings on AZ91D magnesium alloy were investigated in silicate electrolyte.The results show that with increasing extent of voltage,both of the thickness and bonding force of MAO coatings first increase,and then decrease.These parameters are all up to their maximum values when the increase extent of voltage is 20 V.The roughness of the coatings always increases.The coating has the best corrosion resistance when the increase extent of voltage is not below 25 V,and the coating has the best wear resistance when the increase extent of voltage is 10 V.The wear mechanisms for the micro-arc oxidation are abrasive wear and micromachining wear.These are related to their microstructures.

  17. Silicon (BSFR) solar cell AC parameters at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R Anil; Suresh, M.S. [ISRO Satellite Center, Bangalore- 560 017 (India); Nagaraju, J. [Solar Energy and Thermodynamic Laboratory, Department of Instrumentation, Indian Institute of Science, Bangalore- 560 012 (India)

    2005-01-31

    The AC parameters of back surface field reflected (BSFR) silicon solar cell are measured at different cell temperatures (198-348K) both in forward and reverse bias under dark condition using impedance spectroscopy technique. It is found that cell capacitance increases with temperature whereas cell resistance decreases, in forward bias voltage. Beyond maximum power point voltage, the cell inductance (0.28{mu}H) is measured, as the inductive reactance is comparable with cell series resistance. The measured cell parameters (cell capacitance, dynamic resistance, etc) are used to calculate the mean carrier lifetime and diode factor at different cell temperatures.

  18. 阻尼振荡波电压和工频电压下XLPE电缆局部放电特性的对比研究%Comparative Study on Partial Discharge Characteristics of XLPE Cable under Damped Oscillating Wave Voltage and AC Voltage

    Institute of Scientific and Technical Information of China (English)

    薛荣; 张龙; 黄志伟; 张伟; 李洪杰

    2015-01-01

    The partial discharge characteristics of four defects in heat-shrinkable cable accessories, which were termination without stress tube, incorrect use of insulation tape as semi-conductive adhesive tape in the middle joint, void and metal particles on the surface of XLPE insulation, were studied by AC volt-age method and damped oscillating wave voltage method. The partial discharge inception voltage and pat-terns under damped oscillating wave voltage and AC voltage were compared. The results show that the two methods are consistent in the study of partial discharge characteristics, and there are obvious differ-ences in the partial discharge statistical characteristics of various defects.%采用工频电压法和阻尼振荡波电压法研究热缩式电缆附件在4种缺陷情况下的局部放电特性,对比分析两种电压情况下的局部放电起始电压和局放模式。结果表明:两种方法在局部放电特性研究中具有一致性,各种缺陷的局部放电统计特征具有较为明显的差异。

  19. Development of Intelligent AC Contactor Controller with Wide-range Input Voltage%智能型宽电压交流接触器控制器的研制

    Institute of Scientific and Technical Information of China (English)

    陈志英; 陈丽安; 于季刚

    2011-01-01

    提出一种智能型宽电压交流接触器控制器的研制方案.该控制器对施加在接触器线圈两端的电压采用PWM控制及自适应调节,使普通交流接触器实现了在宽范围交直流输入电压(AC 24~380 V或DC 24~220 V)内稳定可靠工作,具有很好的通用性,大幅度减少了产品种类;同时使接触器还可实现节能、无声运行、无弧或少弧分断、在线设置、显示、远程通信和远程操作等功能,提高了交流接触器的性能指标.%This paper presents a controller's design proposal of intelligently controlled AC contactor with wide-range input voltage.The controller can make general AC contactor be operated reliably with a wide range AC or DC input voltage(AC 24~380 V or DC 24~220 V) by using PWM control and self-adaptive adjustment in the coil's voltage,and realize the functions of energy saving,silent operation,less arc or no arc break,setting,display,communication,remote operation etc.Accordingly,the performance and characteristic of the contactor will be enhanced greatly and the types of product will be reduced considerably as well.

  20. Resistance of Trichoplusia ni to Bacillus thuringiensis toxin Cry1Ac is independent of alteration of the cadherin-like receptor for Cry toxins.

    Science.gov (United States)

    Zhang, Xin; Tiewsiri, Kasorn; Kain, Wendy; Huang, Lihua; Wang, Ping

    2012-01-01

    Alteration of binding sites for Bacillus thuringiensis (Bt) toxins in insect midgut is the major mechanism of high-level resistance to Bt toxins in insects. The midgut cadherin is known to be a major binding protein for Bt Cry1A toxins and linkage of Bt-resistance to cadherin gene mutations has been identified in lepidopterans. The resistance to Bt toxin Cry1Ac evolved in greenhouse populations of Trichoplusia ni has been identified to be associated with the down-regulation of an aminopeptidase N (APN1) gene by a trans-regulatory mechanism and the resistance gene has been mapped to the locus of an ABC transporter (ABCC2) gene. However, whether cadherin is also involved with Cry1Ac-resistance in T. ni requires to be understood. Here we report that the Cry1Ac-resistance in T. ni is independent of alteration of the cadherin. The T. ni cadherin cDNA was cloned and the cadherin sequence showed characteristic features known to cadherins from Lepidoptera. Various T. ni cadherin gene alleles were identified and genetic linkage analysis of the cadherin alleles with Cry1Ac-resistance showed no association of the cadherin gene with the Cry1Ac-resistance in T. ni. Analysis of cadherin transcripts showed no quantitative difference between the susceptible and Cry1Ac-resistant T. ni larvae. Quantitative proteomic analysis of midgut BBMV proteins by iTRAQ-2D-LC-MS/MS determined that there was no quantitative difference in cadherin content between the susceptible and the resistant larvae and the cadherin only accounted for 0.0014% (mol%) of the midgut BBMV proteins, which is 1/300 of APN1 in molar ratio. The cadherin from both the susceptible and resistant larvae showed as a 200-kDa Cry1Ac-binding protein by toxin overlay binding analysis, and nano-LC-MS/MS analysis of the 200-kDa cadherin determined that there is no quantitative difference between the susceptible and resistant larvae. Results from this study indicate that the Cry1Ac-resistance in T. ni is independent of cadherin

  1. Resistance of Trichoplusia ni to Bacillus thuringiensis toxin Cry1Ac is independent of alteration of the cadherin-like receptor for Cry toxins.

    Directory of Open Access Journals (Sweden)

    Xin Zhang

    Full Text Available Alteration of binding sites for Bacillus thuringiensis (Bt toxins in insect midgut is the major mechanism of high-level resistance to Bt toxins in insects. The midgut cadherin is known to be a major binding protein for Bt Cry1A toxins and linkage of Bt-resistance to cadherin gene mutations has been identified in lepidopterans. The resistance to Bt toxin Cry1Ac evolved in greenhouse populations of Trichoplusia ni has been identified to be associated with the down-regulation of an aminopeptidase N (APN1 gene by a trans-regulatory mechanism and the resistance gene has been mapped to the locus of an ABC transporter (ABCC2 gene. However, whether cadherin is also involved with Cry1Ac-resistance in T. ni requires to be understood. Here we report that the Cry1Ac-resistance in T. ni is independent of alteration of the cadherin. The T. ni cadherin cDNA was cloned and the cadherin sequence showed characteristic features known to cadherins from Lepidoptera. Various T. ni cadherin gene alleles were identified and genetic linkage analysis of the cadherin alleles with Cry1Ac-resistance showed no association of the cadherin gene with the Cry1Ac-resistance in T. ni. Analysis of cadherin transcripts showed no quantitative difference between the susceptible and Cry1Ac-resistant T. ni larvae. Quantitative proteomic analysis of midgut BBMV proteins by iTRAQ-2D-LC-MS/MS determined that there was no quantitative difference in cadherin content between the susceptible and the resistant larvae and the cadherin only accounted for 0.0014% (mol% of the midgut BBMV proteins, which is 1/300 of APN1 in molar ratio. The cadherin from both the susceptible and resistant larvae showed as a 200-kDa Cry1Ac-binding protein by toxin overlay binding analysis, and nano-LC-MS/MS analysis of the 200-kDa cadherin determined that there is no quantitative difference between the susceptible and resistant larvae. Results from this study indicate that the Cry1Ac-resistance in T. ni is

  2. Tedizolid inhibits MUC5AC production induced by methicillin-resistant Staphylococcus aureus in human airway epithelial cells.

    Science.gov (United States)

    Takeda, Kazuaki; Kaku, Norihito; Morinaga, Yoshitomo; Kosai, Kosuke; Uno, Naoki; Imamura, Yoshifumi; Hasegawa, Hiroo; Miyazaki, Taiga; Izumikawa, Koichi; Mukae, Hiroshi; Yanagihara, Katsunori

    2017-09-01

    The innate immune system plays an important role in early immunity against respiratory tract infection. Although airway epithelial cells produce mucus to eliminate pathogens and irritants, hypersecretion of mucus is harmful for the host as it may cause airway obstruction and inhibit influx of antimicrobial agents. It has been reported that several antimicrobial agents have an immunomodulatory effect in vitro and in vivo, but little is known about whether tedizolid, a novel oxazolidinone, can modulate immune responses. In this study, we evaluated whether tedizolid can suppress MUC5AC production in human airway epithelial cells stimulated by methicillin-resistant Staphylococcus aureus (MRSA). Compared with the control, tedizolid significantly inhibited MUC5AC protein production and mRNA overexpression at concentrations of both 2 and 10 μg/mL (representative of trough and peak concentrations in human epithelial lining fluid). Among the mitogen-activated protein kinase inhibitors tested, only extracellular signal-regulated protein kinase 1/2 (ERK1/2) phosphorylation was inhibited by tedizolid as indicated by western blot analysis. These results indicate that tedizolid inhibits the overproduction of MUC5AC protein by inhibiting phosphorylation of ERK1/2. This study revealed that tedizolid suppresses excessive mucin production in human airway epithelial cells. The immunomodulatory effect of tedizolid may improve outcomes in patients with severe respiratory infectious diseases caused by MRSA. Copyright © 2017 Japanese Society of Chemotherapy and The Japanese Association for Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  3. Intrawire resistance, AC loss and strain dependence of critical current in MgB2 wires with and without cold high-pressure densification

    NARCIS (Netherlands)

    Zhou, C.; Gao, P.; Krooshoop, H.J.G.; Dhallé, M.M.J.; Sumption, M.D.; Rindfleisch, M.; Tomsic, M.; Küllich, M.; Senatore, C.; Nijhuis, A.

    2014-01-01

    The intrawire resistance and alternating current (AC) loss of two MgB2 wires with filaments surrounded by Nb barriers have been measured and analyzed. Relatively high values of filament-to-matrix contact resistivity are found in the MgB2 wires; the values are two or three orders higher than those co

  4. Efficacy of genetically modified Bt toxins alone and in combinations against pink bollworm resistant to Cry1Ac and Cry2Ab

    Science.gov (United States)

    Evolution of resistance in pests threatens the long-term success of transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt). Previous work showed that genetically modified Bt toxins Cry1AbMod and Cry1AcMod effectively countered resistance to native Bt toxins Cry1Ab and ...

  5. Downregulation and Mutation of a Cadherin Gene Associated with Cry1Ac Resistance in the Asian Corn Borer, Ostrinia furnacalis (Guenée

    Directory of Open Access Journals (Sweden)

    Tingting Jin

    2014-09-01

    Full Text Available Development of resistance in target pests is a major threat to long-term use of transgenic crops expressing Bacillus thuringiensis (Bt Cry toxins. To manage and/or delay the evolution of resistance in target insects through the implementation of effective strategies, it is essential to understand the basis of resistance. One of the most important mechanisms of insect resistance to Bt crops is the alteration of the interactions between Cry toxins and their receptors in the midgut. A Cry1Ac-selected strain of Asian corn borer (ACB, Ostrinia furnacalis, a key pest of maize in China, evolved three mutant alleles of a cadherin-like protein (OfCAD (MPR-r1, MPR-r2 and MPR-r3, which mapped within the toxin-binding region (TBR. Each of the three mutant alleles possessed two or three amino acid substitutions in this region, especially Thr1457→Ser. In highly resistant larvae (ACB-Ac200, MPR-r2 had a 26-amino acid residue deletion in the TBR, which resulted in reduced binding of Cry1Ac compared to the MPR from the susceptible strain, suggesting that the number of amino acid deletions influences the level of resistance. Furthermore, downregulation of OfCAD gene (ofcad transcription was observed in the Cry1Ac resistant strain, ACB-Ac24, suggesting that Cry1Ac resistance in ACB is associated with the downregulation of the transcript levels of the cadherin-like protein gene. The OfCAD identified from ACB exhibited a high degree of similarity to other members of the cadherin super-family in lepidopteran species.

  6. MAPK signaling pathway alters expression of midgut ALP and ABCC genes and causes resistance to Bacillus thuringiensis Cry1Ac toxin in diamondback moth.

    Directory of Open Access Journals (Sweden)

    Zhaojiang Guo

    2015-04-01

    Full Text Available Insecticidal crystal toxins derived from the soil bacterium Bacillus thuringiensis (Bt are widely used as biopesticide sprays or expressed in transgenic crops to control insect pests. However, large-scale use of Bt has led to field-evolved resistance in several lepidopteran pests. Resistance to Bt Cry1Ac toxin in the diamondback moth, Plutella xylostella (L., was previously mapped to a multigenic resistance locus (BtR-1. Here, we assembled the 3.15 Mb BtR-1 locus and found high-level resistance to Cry1Ac and Bt biopesticide in four independent P. xylostella strains were all associated with differential expression of a midgut membrane-bound alkaline phosphatase (ALP outside this locus and a suite of ATP-binding cassette transporter subfamily C (ABCC genes inside this locus. The interplay between these resistance genes is controlled by a previously uncharacterized trans-regulatory mechanism via the mitogen-activated protein kinase (MAPK signaling pathway. Molecular, biochemical, and functional analyses have established ALP as a functional Cry1Ac receptor. Phenotypic association experiments revealed that the recessive Cry1Ac resistance was tightly linked to down-regulation of ALP, ABCC2 and ABCC3, whereas it was not linked to up-regulation of ABCC1. Silencing of ABCC2 and ABCC3 in susceptible larvae reduced their susceptibility to Cry1Ac but did not affect the expression of ALP, whereas suppression of MAP4K4, a constitutively transcriptionally-activated MAPK upstream gene within the BtR-1 locus, led to a transient recovery of gene expression thereby restoring the susceptibility in resistant larvae. These results highlight a crucial role for ALP and ABCC genes in field-evolved resistance to Cry1Ac and reveal a novel trans-regulatory signaling mechanism responsible for modulating the expression of these pivotal genes in P. xylostella.

  7. Desing and Making of Digital AC Voltage Meter Based on MC14433%基于MC14433交流电压表的设计与制作

    Institute of Scientific and Technical Information of China (English)

    濮霞; 胡亚刚; 黄天辰; 郎宾

    2013-01-01

    It is designed of digital AC voltage meter based on the three and a half A/D converter MC14433.The voltage meter is used the operational amplifier and integrated multi-channel analog switch circuit CD4052 to realize automatic range switching,it complete measurement system.The system is capable of 0~200 V AC voltage automatic conversion range measurement.It use pure hardware circuit,and has the advantages of low cost,simple structure,convenient operation.%设计制作了一种基于MC14433三位半A/D转换器的数字交流电压表,采用运算放大器和集成多路模拟开关电路CD4052,实现了电压表量程自动切换,构成完备的测量系统.系统可以对0~200 V交流电压进行量程自动转换的测量.电路采用纯硬件实现,具有成本低、结构简单和操作方便的优点.

  8. A Coordinated Control for Photovoltaic Generators and Energy Storages in Low-Voltage AC/DC Hybrid Microgrids under Islanded Mode

    DEFF Research Database (Denmark)

    Liu, Yao; Hou, Xiaochao; Wang, Xiaofeng;

    2016-01-01

    The increasing penetration of renewable generators can be a significant challenge due to the fluctuation of their power generation. Energy storage (ES) units are one solution to improve power supply quality and guarantee system stability. In this paper, a hybrid microgrid is built based...... on photovoltaic (PV) generator and ES; and coordinated control is proposed and developed to achieve power management in a decentralized manner. This control scheme contains three different droop strategies according to characteristics of PV and ES. First, the modified droop control is proposed for PV, which can...... for alternating current (AC)-side ES. Thus, the ES lifetime is prolonged. Moreover, interlinking converters (ICs) provide a bridge between AC/DC buses in a hybrid microgrid. The power control of IC is enabled when the AC- or DC-side suffer from active power demand shortage. In particular, if the AC microgrid does...

  9. 厂外排水管道交流稳态干扰防护设计%Protection Design against AC Steady-state Interference for Water Pipeline near High-voltage Transmission Lines

    Institute of Scientific and Technical Information of China (English)

    程明; 牟华; 黄春蓉; 张平

    2013-01-01

    AC steady-state interference may affect the water pipeline near high-voltage transmission lines. Referring to some related standards, the mitigation objective and protection effect of the AC interference were analyzed, and the Right of Way (ROW) package was used to build modeling and calculation around the mitigation. The calculation results can guide the engineering design.%高压输电线路附近的厂外排水管道可能面临交流稳态干扰影响.结合相关标准要求,对交流干扰缓解目标和防护效果进行探讨分析,并利用自动计算软件包(ROW)分别对缓解前后进行建模计算分析.计算分析结果可以指导工程设计.

  10. Study program to improve the open-circuit voltage of low resistivity single crystal silicon solar cells

    Science.gov (United States)

    Minnucci, J. A.; Matthei, K. W.

    1980-01-01

    The results of a 14 month program to improve the open circuit voltage of low resistivity silicon solar cells are described. The approach was based on ion implantation in 0.1- to 10.0-ohm-cm float-zone silicon. As a result of the contract effort, open circuit voltages as high as 645 mV (AMO 25 C) were attained by high dose phosphorus implantation followed by furnace annealing and simultaneous SiO2 growth. One key element was to investigate the effects of bandgap narrowing caused by high doping concentrations in the junction layer. Considerable effort was applied to optimization of implant parameters, selection of furnace annealing techniques, and utilization of pulsed electron beam annealing to minimize thermal process-induced defects in the completed solar cells.

  11. Resistance of Trichoplusia ni Populations Selected by Bacillus thuringiensis Sprays to Cotton Plants Expressing Pyramided Bacillus thuringiensis Toxins Cry1Ac and Cry2Ab

    Science.gov (United States)

    Kain, Wendy; Song, Xiaozhao; Janmaat, Alida F.; Zhao, Jian-Zhou; Myers, Judith; Shelton, Anthony M.

    2014-01-01

    Two populations of Trichoplusia ni that had developed resistance to Bacillus thuringiensis sprays (Bt sprays) in commercial greenhouse vegetable production were tested for resistance to Bt cotton (BollGard II) plants expressing pyramided Cry1Ac and Cry2Ab. The T. ni colonies resistant to Bacillus thuringiensis serovar kurstaki formulations were not only resistant to the Bt toxin Cry1Ac, as previously reported, but also had a high frequency of Cry2Ab-resistant alleles, exhibiting ca. 20% survival on BollGard II foliage. BollGard II-resistant T. ni strains were established by selection with BollGard II foliage to further remove Cry2Ab-sensitive alleles in the T. ni populations. The BollGard II-resistant strains showed incomplete resistance to BollGard II, with adjusted survival values of 0.50 to 0.78 after 7 days. The resistance to the dual-toxin cotton plants was conferred by two genetically independent resistance mechanisms: one to Cry1Ac and one to Cry2Ab. The 50% lethal concentration of Cry2Ab for the resistant strain was at least 1,467-fold that for the susceptible T. ni strain. The resistance to Cry2Ab in resistant T. ni was an autosomally inherited, incompletely recessive monogenic trait. Results from this study indicate that insect populations under selection by Bt sprays in agriculture can be resistant to multiple Bt toxins and may potentially confer resistance to multitoxin Bt crops. PMID:25480752

  12. Optimal PowerFlow (OPF) Model with Unified AC-DC Load Flow and Optimal Commitmentfor an AC-catenary Railway Power Supply System (RPSS) fed by aHigh Voltage DC (HVDC) transmission line

    OpenAIRE

    Abrahamsson, Lars; Östlund, Stefan; Söder, Lennart

    2012-01-01

    In this paper an alternative railway power systems design based on an HVDC feeder is studied. The HVDC feeder is connected to the catenary by converters. Such an HVDC line is also appropriate for DC-fed railways and AC-fed railways working at public frequency. A unit commitment optimal power flow model has been developed and is applied on a test system. In this paper, the model is presented in detail. The model, in the form of an MINLP program, uses unified AC-DC power flow to minimize the en...

  13. 船用交流中压断路器开断性能相关参数分析%Analysis of Parameters for Breaking Performance of Marine Medium Voltage AC Circuit Breakers

    Institute of Scientific and Technical Information of China (English)

    杨青

    2013-01-01

    According to the characteristics of marine medium voltage power system,the parameters closely related to the breaking performance of medium voltage AC circuit breaker were analyzed.It is shown that the key performance parameters in land standards,such as rated breaking current,making current,power frequency recovery voltage,transient recovery voltage,electrical life and so on,basically meet the marine requirements after conversion. But there are also some individual parameters need to be studied further to decide.%根据船舶中压电力系统的特点,对中压断路器开断性能密切相关的参数进行了分析。结果表明,陆用标准中额定短路开断电流和关合电流、工频恢复电压和瞬态恢复电压、电寿命等参数经过换算、折算,基本上符合船用要求,个别参数是否合适有待进一步研究。

  14. Effect of crop plants on fitness costs associated with resistance to Bacillus thuringiensis toxins Cry1Ac and Cry2Ab in cabbage loopers

    Science.gov (United States)

    Wang, Ran; Tetreau, Guillaume; Wang, Ping

    2016-01-01

    Fitness costs associated with resistance to Bacillus thuringiensis (Bt) toxins critically impact the development of resistance in insect populations. In this study, the fitness costs in Trichoplusia ni strains associated with two genetically independent resistance mechanisms to Bt toxins Cry1Ac and Cry2Ab, individually and in combination, on four crop plants (cabbage, cotton, tobacco and tomato) were analyzed, in comparison with their near-isogenic susceptible strain. The net reproductive rate (R0) and intrinsic rate of increase (r) of the T. ni strains, regardless of their resistance traits, were strongly affected by the host plants. The ABCC2 gene-linked mechanism of Cry1Ac resistance was associated with relatively low fitness costs, while the Cry2Ab resistance mechanism was associated with higher fitness costs. The fitness costs in the presence of both resistance mechanisms in T. ni appeared to be non-additive. The relative fitness of Bt-resistant T. ni depended on the specific resistance mechanisms as well as host plants. In addition to difference in survivorship and fecundity, an asynchrony of adult emergence was observed among T. ni with different resistance mechanisms and on different host plants. Therefore, mechanisms of resistance and host plants available in the field are both important factors affecting development of Bt resistance in insects. PMID:26868936

  15. Effect of crop plants on fitness costs associated with resistance to Bacillus thuringiensis toxins Cry1Ac and Cry2Ab in cabbage loopers.

    Science.gov (United States)

    Wang, Ran; Tetreau, Guillaume; Wang, Ping

    2016-02-12

    Fitness costs associated with resistance to Bacillus thuringiensis (Bt) toxins critically impact the development of resistance in insect populations. In this study, the fitness costs in Trichoplusia ni strains associated with two genetically independent resistance mechanisms to Bt toxins Cry1Ac and Cry2Ab, individually and in combination, on four crop plants (cabbage, cotton, tobacco and tomato) were analyzed, in comparison with their near-isogenic susceptible strain. The net reproductive rate (R0) and intrinsic rate of increase (r) of the T. ni strains, regardless of their resistance traits, were strongly affected by the host plants. The ABCC2 gene-linked mechanism of Cry1Ac resistance was associated with relatively low fitness costs, while the Cry2Ab resistance mechanism was associated with higher fitness costs. The fitness costs in the presence of both resistance mechanisms in T. ni appeared to be non-additive. The relative fitness of Bt-resistant T. ni depended on the specific resistance mechanisms as well as host plants. In addition to difference in survivorship and fecundity, an asynchrony of adult emergence was observed among T. ni with different resistance mechanisms and on different host plants. Therefore, mechanisms of resistance and host plants available in the field are both important factors affecting development of Bt resistance in insects.

  16. GaAs/Ge solar cell AC parameters under illumination

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R.A.; Suresh, M.S. [ISRO Satellite Center, Bangalore (India); Nagaraju, J. [Indian Institute of Science, Bangalore (India). Department of Instrumentation, Solar Energy Laboratory

    2004-04-01

    The ac parameters of GaAs/Ge solar cell were measured under illumination at different cell temperatures using impedance spectroscopy technique. They are compared with the dark measurements. It is found that the cell capacitance is higher and cell resistance is lower under illumination than in dark for all cell terminal voltages. The cell capacitances at the corresponding maximum power point voltage (terminal) do not vary with temperature where as the cell resistance decreases. The cell capacitance under illumination is estimated from the dark cell capacitance and it is in good agreement with the measured illumination data. (author)

  17. Performance Evaluations of A Single Inductor Type Resonant AC Link Snubber-Assisted Three-Phase Voltage Source Soft-Switching Inverter

    National Research Council Canada - National Science Library

    Yoshida, Masanobu; Hiraki, Eiji; Nakaoka, Mutsuo

    2003-01-01

      This paper presents a novel three-phase voltage source type soft-switching inverter using the main and auxiliary IGBT power module packages in order to reduce their switching power losses as well...

  18. Precision rectifier detectors for ac resistance bridge measurements with application to temperature control systems for irradiation creep experiments

    Energy Technology Data Exchange (ETDEWEB)

    Duncan, M. G.

    1977-05-01

    The suitability of several temperature measurement schemes for an irradiation creep experiment is examined. It is found that the specimen resistance can be used to measure and control the sample temperature if compensated for resistance drift due to radiation and annealing effects. A modified Kelvin bridge is presented that allows compensation for resistance drift by periodically checking the sample resistance at a controlled ambient temperature. A new phase-insensitive method for detecting the bridge error signals is presented. The phase-insensitive detector is formed by averaging the magnitude of two bridge voltages. Although this method is substantially less sensitive to stray reactances in the bridge than conventional phase-sensitive detectors, it is sensitive to gain stability and linearity of the rectifier circuits. Accuracy limitations of rectifier circuits are examined both theoretically and experimentally in great detail. Both hand analyses and computer simulations of rectifier errors are presented. Finally, the design of a temperature control system based on sample resistance measurement is presented. The prototype is shown to control a 316 stainless steel sample to within a 0.15/sup 0/C short term (10 sec) and a 0.03/sup 0/C long term (10 min) standard deviation at temperatures between 150 and 700/sup 0/C. The phase-insensitive detector typically contributes less than 10 ppM peak resistance measurement error (0.04/sup 0/C at 700/sup 0/C for 316 stainless steel or 0.005/sup 0/C at 150/sup 0/C for zirconium).

  19. Correlation of transdermal iontophoretic phenylalanine and mannitol transport: test of the internal standard concept under DC iontophoresis and constant resistance AC iontophoresis conditions.

    Science.gov (United States)

    Yan, Guang; Higuchi, William I; Szabo, Aniko; Li, S Kevin

    2004-07-23

    The purpose of this study was to test the feasibility of using an internal standard approach to predict the transdermal flux of phenylalanine (Phe) across human epidermal membrane (HEM) in vitro during iontophoresis of constant direct current (DC), constant skin resistance alternating current (AC) with DC offset (AC-plus-DC), symmetric constant resistance AC (AC-only), and constant current DC with the application of a polyelectrolyte. Under the constant current DC and AC-plus-DC conditions, a linear relationship between the permeation of Phe and that of mannitol was observed with a slope close to unity. The ratios of the Phe permeability coefficients to those of mannitol during iontophoresis with different HEM samples were essentially constant with significantly smaller inter-sample and intra-sample variabilities than those of the raw Phe permeability coefficient data. This demonstrates that mannitol is a good internal standard for predicting the transdermal iontophoretic flux of Phe under these two conditions. On the other hand, the correlations of the permeability coefficients of Phe and mannitol under the AC-only iontophoresis and iontophoresis with the polyelectrolyte are poorer than those observed during DC and AC-plus-DC iontophoresis. The poor correlations are believed to be related to Phe being a zwitterion and its anionic form in HEM. Previously, iontophoretic transport of glucose has been demonstrated to be essentially the same as that of mannitol. The good correlations between Phe and mannitol transport across HEM during DC and AC-plus-DC iontophoresis in the present study therefore suggest that glucose and its extraction can be used as the internal standard for iontophoretic Phe monitoring.

  20. Cross-resistance responses of CrylAc-selected Heliothis virescens (Lepidoptera: Noctuidae) to the Bacillus thuringiensis protein vip3A.

    Science.gov (United States)

    Jackson, R E; Marcus, M A; Gould, F; Bradley, J R; Van Duyn, J W

    2007-02-01

    One susceptible and three Cry1Ac-resistant strains of tobacco budworm, Heliothis virescens (F.) (Lepidoptera: Noctuidae), were used in laboratory studies to determine the level of cross-resistance between the Bacillus thuringiensis (Berliner) toxins Cry1Ac and Vip3A by using concentration-mortality and leaf tissue experiments. Concentration-mortality data demonstrated that the three Cry1Ac-resistant H. virescens strains, YHD2, KCBhyb, and CxC, were at least 215- to 316-fold resistant to Cry1Ac compared with the susceptible strain, YDK. Results from Vip3A concentration-mortality tests indicated that mortality was similar among all four H. virescens strains. Relative larval growth on Cry1Ac reflected concentration-mortality test results, because YHD2 larval growth was mostly unaffected by the Cry1Ac concentrations tested. Growth ratios for KCBhyb and CXC indicated that they had a more moderate level of resistance to Cry1Ac than did YHD2. Relative larval growth on Vip3A was highly variable at lower concentrations, but it was more consistent on concentrations of Vip3A above 25 microg/ml. Differences in larval growth among strains on Vip3A were not as pronounced as seen in Cry1Ac experiments. Mortality and larval growth also was assessed in leaf tissue bioassays in which YDK, CxC, and KCBhyb neonates were placed onto leaf disks from non-Bt and Bt cotton, Gossypium hirsutum L., for 5 d. Three Bt lines were used in an initial bioassay and consisted of two Vip3A-containing lines, COT203 and COT102, and a Cry1Ac-producing line. Mortality of KCBhyb and CXC was lower than that of YDK larvae in the presence of leaf tissue from the Cry1Ac-producing line. Additionally, increased larval growth and leaf tissue consumption on Cry1Ac-containing leaf disks was observed for KCBhyb and CXC. Mortality and larval weights were similar among strains when larvae were fed leaf tissue of either non-Bt, COT203, or COT102. A subsequent leaf tissue bioassay was conducted that evaluated four

  1. Improvement in nano-hardness and corrosion resistance of low carbon steel by plasma nitriding with negative DC bias voltage

    Science.gov (United States)

    Alim, Mohamed Mounes; Saoula, Nadia; Tadjine, Rabah; Hadj-Larbi, Fayçal; Keffous, Aissa; Kechouane, Mohamed

    2016-10-01

    In this work, we study the effect of plasma nitriding on nano-hardness and corrosion resistance of low carbon steel samples. The plasma was generated through a radio-frequency inductively coupled plasma source. The substrate temperature increased (by the self-induced heating mechanism) with the treatment time for increasing negative bias voltages. X-rays diffraction analysis revealed the formation of nitride phases (ɛ-Fe2-3N and γ'-Fe4N) in the compound layer of the treated samples. A phase transition occurred from 3.5 kV to 4.0 kV and was accompanied by an increase in the volume fraction of the γ'-Fe4N phase and a decrease in that of the ɛ-Fe2-3N phase. Auger electron spectroscopy revealed a deep diffusion of the implanted nitrogen beyond 320 nm. The nano-hardness increased by ~400% for the nitrogen-implanted samples compared to the untreated state, the nitride phases are believed to participate to the hardening. Potentiodynamic polarization measurements revealed that the plasma nitriding has improved the corrosion resistance behavior of the material. When compared to the untreated state, the sample processed at 4.0 kV exhibits a shift of +500 mV and a reduction to 3% in its corrosion current. These results were obtained for relatively low bias voltages and short treatment time (2 h).

  2. 外部电压源法测试大电压LED器件/模块热阻%Measuring thermal resistance for high voltage LED device and module by applying ex ternal voltage source

    Institute of Scientific and Technical Information of China (English)

    陈国龙; 朱丽虹; 郭自泉; 张纪红; 吕毅军; 高玉琳; 陈忠

    2013-01-01

    热阻是衡量LED器件/模块散热性能的重要参数。针对大电压LED器件/模块,实验采用 T3Ster/T eraled热光参数测试仪,利用外部电压源供电方法,实现了对超过仪器量程的大电压L ED器件的热阻测试。该方法拓展了热阻测试仪的常规测量范围,使正向电压大于15 V的L ED器件/模块的热阻测试成为可能。%Thermal resistance is a key parameter for evaluating thermal performance of LED device/module . Reliable measurement of thermal resistance becomes extremely important .Aiming at that the high voltage LED device/module has been applied popularly in lighting ,an improved thermal resistance measurement method for LED device/module with forward voltage larger than 15V is achieved by applying external voltage source to the T3Ster/Teraled .The result shows that the external voltage source method can effectively expand the testing range of thermal resistance tester .

  3. Novel Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Varroa destructor Populations from the Southeastern USA

    Science.gov (United States)

    González-Cabrera, Joel; Rodríguez-Vargas, Sonia; Davies, T. G. Emyr; Field, Linda M.; Schmehl, Daniel; Ellis, James D.; Krieger, Klemens; Williamson, Martin S.

    2016-01-01

    The parasitic mite Varroa destructor has a significant worldwide impact on bee colony health. In the absence of control measures, parasitized colonies invariably collapse within 3 years. The synthetic pyrethroids tau-fluvalinate and flumethrin have proven very effective at managing this mite within apiaries, but intensive control programs based mainly on one active ingredient have led to many reports of pyrethroid resistance. In Europe, a modification of leucine to valine at position 925 (L925V) of the V. destructor voltage-gated sodium channel was correlated with resistance, the mutation being found at high frequency exclusively in hives with a recent history of pyrethroid treatment. Here, we identify two novel mutations, L925M and L925I, in tau-fluvalinate resistant V. destructor collected at seven sites across Florida and Georgia in the Southeastern region of the USA. Using a multiplexed TaqMan® allelic discrimination assay, these mutations were found to be present in 98% of the mites surviving tau-fluvalinate treatment. The mutations were also found in 45% of the non-treated mites, suggesting a high potential for resistance evolution if selection pressure is applied. The results from a more extensive monitoring programme, using the Taqman® assay described here, would clearly help beekeepers with their decision making as to when to include or exclude pyrethroid control products and thereby facilitate more effective mite management programmes. PMID:27191597

  4. Novel Mutations in the Voltage-Gated Sodium Channel of Pyrethroid-Resistant Varroa destructor Populations from the Southeastern USA.

    Directory of Open Access Journals (Sweden)

    Joel González-Cabrera

    Full Text Available The parasitic mite Varroa destructor has a significant worldwide impact on bee colony health. In the absence of control measures, parasitized colonies invariably collapse within 3 years. The synthetic pyrethroids tau-fluvalinate and flumethrin have proven very effective at managing this mite within apiaries, but intensive control programs based mainly on one active ingredient have led to many reports of pyrethroid resistance. In Europe, a modification of leucine to valine at position 925 (L925V of the V. destructor voltage-gated sodium channel was correlated with resistance, the mutation being found at high frequency exclusively in hives with a recent history of pyrethroid treatment. Here, we identify two novel mutations, L925M and L925I, in tau-fluvalinate resistant V. destructor collected at seven sites across Florida and Georgia in the Southeastern region of the USA. Using a multiplexed TaqMan® allelic discrimination assay, these mutations were found to be present in 98% of the mites surviving tau-fluvalinate treatment. The mutations were also found in 45% of the non-treated mites, suggesting a high potential for resistance evolution if selection pressure is applied. The results from a more extensive monitoring programme, using the Taqman® assay described here, would clearly help beekeepers with their decision making as to when to include or exclude pyrethroid control products and thereby facilitate more effective mite management programmes.

  5. Impact of parasitic resistance on the ESD robustness of high-voltage devices

    Institute of Scientific and Technical Information of China (English)

    Lin Lijuan; Jiang Lingli; Fan Hang; Zhang Bo

    2012-01-01

    The impacts ofsubstrate parasitic resistance and drain ballast resistance on electrostatic discharge (ESD)robustness of LDMOS are analyzed.By increasing the two parasitic resistances,the ESD robustness of LDMOS are significantly improved.The proposed structures have been successfully verified in a 0.35 μm BCD process without using additional process steps.Experimental results show that the second breakdown current of the optimal structure increases to 3.5 A,which is about 367% of the original device.

  6. Effect of Operation Voltage and Gas Ratio on Time Resolution of Resistive Plate Chamber

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>RPC is a gas detector made of high resistive material, which aims at detecting the track and time of high energy charged particles. The techniques for RPC are simple, which makes it easy for mass

  7. Measurement of silicon and GaAs/Ge solar cells ac parameters

    Energy Technology Data Exchange (ETDEWEB)

    Deshmukh, M.P.; Nagaraju, J. [Indian Institute of Science, Bangalore (India). Dept. of Instrumentation

    2005-01-01

    The ac parameters (cell capacitance and cell resistance) of Silicon (Si) and Gallium Arsenide (GaAs/Ge) solar cells are measured at different temperatures using time domain technique. The cell capacitance is calculated from the Open circuit voltage decay (OCVD) and the cell resistance from solar cell I-V characteristics measured under dark condition. It is observed that the solar cell capacitance increases whereas the cell resistance decreases with increase in temperature. (author)

  8. Transcranial low voltage pulsed electromagnetic fields in patients with treatment-resistant depression

    DEFF Research Database (Denmark)

    Martiny, Klaus Per Juul; Lunde, Marianne; Bech, Per

    2010-01-01

    BACKGROUND: Approximately 30% of patients with depression are resistant to antidepressant drugs. Repetitive transcranial magnetic stimulation (rTMS) has been found effective in combination with antidepressants in this patient group. The aim of this study was to evaluate the antidepressant effect...... of a new principle using low-intensity transcranially applied pulsed electromagnetic fields (T-PEMF) in combination with antidepressants in patients with treatment-resistant depression. METHODS: This was a sham-controlled double-blind study comparing 5 weeks of active or sham T-PEMF in patients......-resistant depression. Few side effects were observed. Mechanism of the antidepressant action, in light of the known effects of PEMF stimulation to the brain, is discussed....

  9. OPTIMIZATION OF SURFACE RESISTIVITY AND RELATIVE PERMITTIVITY OF SILICONE RUBBER FOR HIGH VOLTAGE APPLICATION USING RESPONSE SURFACE METHODOLOGY

    Directory of Open Access Journals (Sweden)

    N.N. Ali

    2017-06-01

    Full Text Available Silicone Rubber (SiR is considered as one of the most established insulator in High Voltage (HV industry. SiR possess a great function ability such as its lighter weight, great heat resistance and substantial electrical insulation properties. Dynamic research were performed all around the world in order to explore the unique insulating behavior of SiR but very little are done on the optimization of SiR in term of their processing parameters and formulation. In this work, four materials and processing factors were introduced; A: Alumina Trihydrate (ATH, B: Dicumyl-Peroxide (DCP, C: mixing speed and D: mixing time in order to analyze its contribution towards improving the surface resistivity and relative permittivity of SIR rubber. The factors range were set based on prior screening and are defined as; ATH (10 – 50 pphr, Dicumyl Peroxide (0.50 -1.50 pphr, speed of mixer (40 – 70 rpm and mixing period (5 – 10 mins which were then varied accordingly to produce an overall 19 samples of SiR blends. The testing results were analyzed using statistical Design of Experiment (DOE by applying two level full factorial from Design Expert Software (v10 to discover the inter-correlation between the factors studied and benefaction of each factor in improving both surface resistivity and relative permittivity responses of produced SiR blends. The model analysis on surface resistivity shows the coefficient of determination R2 value of 88.72% while the one for relative permittivity shows R2 value of 82.34 %. Combination of both dependent variables had yielded an optimization suggestion for SiR formulation and processing strategy of ATH: 50 pphr, DCP: 0.50 pphr, mixing speed: 70 rpm and mixing period: 10 mins with the desirability level of 0.835. The optimized formulation had resulted in the production of SiR blend with the characteristic of surface resistivity of 1.02039x10^14 Ω/sq and relative permittivity of 4.0231, respectively. In conclusion, it can be

  10. System and method for monitoring and controlling stator winding temperature in a de-energized AC motor

    Science.gov (United States)

    Lu, Bin; Luebke, Charles John; Habetler, Thomas G.; Zhang, Pinjia; Becker, Scott K.

    2011-12-27

    A system and method for measuring and controlling stator winding temperature in an AC motor while idling is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of a multi-phase AC motor. The circuit further includes a plurality of switching devices to control current flow and terminal voltages in the multi-phase AC motor and a controller connected to the circuit. The controller is configured to activate the plurality of switching devices to create a DC signal in an output of the motor control device corresponding to an input to the multi-phase AC motor, determine or estimate a stator winding resistance of the multi-phase AC motor based on the DC signal, and estimate a stator temperature from the stator winding resistance. Temperature can then be controlled and regulated by DC injection into the stator windings.

  11. Transcranial low voltage pulsed electromagnetic fields in patients with treatment-resistant depression

    DEFF Research Database (Denmark)

    Martiny, Klaus Per Juul; Lunde, Marianne; Bech, Per

    2010-01-01

    of a new principle using low-intensity transcranially applied pulsed electromagnetic fields (T-PEMF) in combination with antidepressants in patients with treatment-resistant depression. METHODS: This was a sham-controlled double-blind study comparing 5 weeks of active or sham T-PEMF in patients...

  12. Differential expression of T- and L-type voltage-dependent calcium channels in renal resistance vessels

    DEFF Research Database (Denmark)

    Hansen, Pernille B. Lærkegaard; Jensen, Boye L.; Andreasen, D;

    2001-01-01

    .2 protein was demonstrated by immunochemical labeling of rat preglomerular vasculature and juxtamedullary efferent arterioles and vasa recta. Cortical efferent arterioles were not immunopositive. Recordings of intracellular calcium concentration with digital fluorescence imaging microscopy showed......The distribution of voltage-dependent calcium channels in kidney pre- and postglomerular resistance vessels was determined at the molecular and functional levels. Reverse transcription-polymerase chain reaction analysis of microdissected rat preglomerular vessels and cultured smooth muscle cells...... showed coexpression of mRNAs for T-type subunits (Ca(V)3.1, Ca(V)3.2) and for an L-type subunit (Ca(V)1.2). The same expression pattern was observed in juxtamedullary efferent arterioles and outer medullary vasa recta. No calcium channel messages were detected in cortical efferent arterioles. Ca(V)1...

  13. Differential expression of T- and L-type voltage-dependent calcium channels in renal resistance vessels

    DEFF Research Database (Denmark)

    Hansen, Pernille B. Lærkegaard; Jensen, Boye L.; Andreasen, D

    2001-01-01

    The distribution of voltage-dependent calcium channels in kidney pre- and postglomerular resistance vessels was determined at the molecular and functional levels. Reverse transcription-polymerase chain reaction analysis of microdissected rat preglomerular vessels and cultured smooth muscle cells...... showed coexpression of mRNAs for T-type subunits (Ca(V)3.1, Ca(V)3.2) and for an L-type subunit (Ca(V)1.2). The same expression pattern was observed in juxtamedullary efferent arterioles and outer medullary vasa recta. No calcium channel messages were detected in cortical efferent arterioles. Ca(V)1.......2 protein was demonstrated by immunochemical labeling of rat preglomerular vasculature and juxtamedullary efferent arterioles and vasa recta. Cortical efferent arterioles were not immunopositive. Recordings of intracellular calcium concentration with digital fluorescence imaging microscopy showed...

  14. Chromium-modified a-C films with advanced structural, mechanical and corrosive-resistant characteristics

    Science.gov (United States)

    Ming, Miao Yi; Jiang, Xiaohong; Piliptsou, D. G.; Zhuang, Yuzhao; Rogachev, A. V.; Rudenkov, A. S.; Balmakou, A.

    2016-08-01

    To improve structural, mechanical and chemical properties of diamond-like carbon films, we developed amorphous carbon chromium-modified composite films fabricated by means of cathode magnetic filtered arc deposition. The properties were analyzed by Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy for the purpose of the structure characterization, elemental analysis and topology examination. Moreover, we also assessed residual stress, the coefficient of friction, hardness, the elastic modulus and corrosion parameters through X-ray double-crystal surface profilometry, tribo-testing, nanoindenter-testing, as well as contact angle measurements and potentiodynamic polarization analysis. As a result of a comparative analysis, we revealed a substantial improvement in the characteristics of developed composite films in comparison with amorphous carbon films. For example, Cr-modification is resulted, in greater integrated performance, toughness and corrosion resistance; the residual stress was reduced substantially.

  15. Analytical Solution for Model-Based Dynamic Power Factor Measurement in AC Resistance Spot Welding

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    On the basis of welding transformer circuit model, a new measuring method was proposed. This method measures the peak angle of the welding current, and then calculates the dynamic power factor in each half-wave.An artificial neural network is trained and used to generate simulation data for the analytical solution, i.e. a highorder binary polynomial, which can be easily adopted to calculate the power factor online. The tailored sensing and computing system ensures that the method possesses a real-time computational capacity and satisfying accuracy. A DSP-based resistance spot welding monitoring system was developed to perform ANN computation. The experimental results suggest that this measuring method is feasible.

  16. Cathodic voltage-controlled electrical stimulation of titanium implants as treatment for methicillin-resistant Staphylococcus aureus periprosthetic infections.

    Science.gov (United States)

    Ehrensberger, Mark T; Tobias, Menachem E; Nodzo, Scott R; Hansen, Lisa A; Luke-Marshall, Nicole R; Cole, Ross F; Wild, Linda M; Campagnari, Anthony A

    2015-02-01

    Effective treatment options are often limited for implant-associated orthopedic infections. In this study we evaluated the antimicrobial effects of applying cathodic voltage-controlled electrical stimulation (CVCES) of -1.8 V (vs. Ag/AgCl) to commercially pure titanium (cpTi) substrates with preformed biofilm-like structures of methicillin-resistant Staphylococcus aureus (MRSA). The in vitro studies showed that as compared to the open circuit potential (OCP) conditions, CVCES of -1.8 V for 1 h significantly reduced the colony-forming units (CFU) of MRSA enumerated from the cpTi by 97% (1.89 × 106 vs 6.45 × 104 CFU/ml) and from the surrounding solution by 92% (6.63 × 105 vs. 5.15 × 104 CFU/ml). The in vivo studies, utilizing a rodent periprosthetic infection model, showed that as compared to the OCP conditions, CVCES at -1.8 V for 1 h significantly reduced MRSA CFUs in the bone tissue by 87% (1.15 × 105 vs. 1.48 × 104 CFU/ml) and reduced CFU on the cpTi implant by 98% (5.48 × 104 vs 1.16 × 103 CFU/ml). The stimulation was not associated with histological changes in the host tissue surrounding the implant. As compared to the OCP conditions, the -1.8 V stimulation significantly increased the interfacial capacitance (18.93 vs. 98.25 μF/cm(2)) and decreased polarization resistance (868,250 vs. 108 Ω-cm(2)) of the cpTi. The antimicrobial effects are thought to be associated with these voltage-dependent electrochemical surface properties of the cpTi.

  17. 负偏压法测试大电压LED器件热阻%Measuring thermal resistance for high voltage LED device and module by applying negative bias voltage

    Institute of Scientific and Technical Information of China (English)

    陈国龙; 雷瑞瑞; 陈焕庭; 陈莹亮; 吕毅军; 高玉琳; 朱丽虹; 陈忠

    2012-01-01

    热阻是衡量LED器件散热性能的重要热学参数.采用外接负偏压恒压源方法,分别使用T3Ster/Teraled热光参数测试仪和NC2991热阻仪对正向电压超过仪器量程的同一型号功率型LED的热阻进行测试,并对两种测试结果的误差进行比较分析讨论.该方法拓展了热阻仪测量范围,使正向电压大于5V的LED器件/模块的热阻测试成为可能.%Thermal resistance is a key parameter on rating the heat dissipating capability of LEDs, so its measurement becomes particularly essential. A thermal resistance measurement method for high voltage LED device and module is provided here, which can measure LED sample with forward voltage larger than 5V by applying negative bias voltage to the T3Ster/Teraled and the NC2991 thermal resistance testers respectively. The results are further compared and discussed and prove to effectively expand the testing range of thermal resistance tester.

  18. Application of Partial Discharge Detection Technique in AC Voltage Withstand Test of HV Cable%局放测试技术在高压电缆交流耐压试验中的应用

    Institute of Scientific and Technical Information of China (English)

    罗容波; 詹清华; 王岩

    2013-01-01

      针对交流耐压试验方法在发现电缆缺陷上的不足,提出在高压电缆交流耐压试验中外接局放监视仪来避免耐压试验对电缆造成损伤。通过建立仿真电路和搭建实验室模型,研究了现场干扰信号与电缆自身局放信号的时域、频域、波形和极性的特征,总结出一套适用于高压电缆现场局放测试的方法。应用该方法对新敷设的110 kV高压电缆进行检测,发现了高压电缆终端的缺陷,证实了此测试方法的有效性。%  In view of the shortcomings of AC withstand voltage test method in discovering the faults of HV cable, a partial discharge monitoring instrument is external connected with AC withstand voltage test to avoid the damage of cable. The time domain, frequency domain, waveform and polarity characteristics of the interference signal and the signal of cable were studied by simulation and experimental research, and a method suitable for the partial discharge test of HV cable was summarized. The termination fault of a new HV cable was found by applying the method, which confirms the validity of the method.

  19. Series resistance mapping of Cu(In,Ga)Se{sub 2} solar cells by voltage dependent electroluminescence

    Energy Technology Data Exchange (ETDEWEB)

    Daume, Felix; Puttnins, Stefan [Solarion AG, Ostende 5, 04288 Leipzig (Germany); Institut fuer Experimentelle Physik II, Universitaet Leipzig, Linnestr. 5, 04103 Leipzig (Germany); Scheit, Christian; Rahm, Andreas [Solarion AG, Ostende 5, 04288 Leipzig (Germany); Grundmann, Marius [Institut fuer Experimentelle Physik II, Universitaet Leipzig, Linnestr. 5, 04103 Leipzig (Germany)

    2011-07-01

    Cu(In,Ga)Se{sub 2} (CIGSe) thin film solar cells deposited on flexible polyimide foil promising innovative applications and a fabrication in continuous roll-to-roll processes currently reach efficiencies up to 17.6 %. The optimization of the solar cell efficiency requires the reduction of inherent losses in the cell. In order to achieve this goal preferably spatially resolved access to parameters characterizing ohmic losses like series and shunt resistances are indispensable. We apply an interpretation method for electroluminescence (EL) images taken at different voltages which is known for solar cells made of crystalline silicon from literature to solar cells made of polycrystalline CIGSe. The theory of this method to obtain a mapping of the series resistance and the EL imaging process as well as the data interpretation ils reviewed and demonstrated on an example. Furthermore, the benefit of this method for the characterization of solar cells under accelerated aging conditions (damp heat) which is important for the estimation of the long-term stability is shown.

  20. Composite Based EHV AC Overhead Transmission Lines

    DEFF Research Database (Denmark)

    Sørensen, Thomas Kjærsgaard

    Overhead lines at transmission level are the backbone of any national power grid today. New overhead line projects however are at the same time subject to ever greater public resistance due to the lines environmental impact. As full undergrounding of transmission lines at extra high voltage (EHV...... and analysed with regard to the possibilities, limitations and risks widespread application of composite materials on EHV AC overhead transmission lines may present. To form the basis for evaluation of the useability of composite materials, dierent overhead line projects aimed at reducing the environmental...

  1. Critical current density and ac harmonic voltage generation in YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} thin films by the screening technique

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Lopez, Israel O., E-mail: iperez@mda.cinvestav.m [Applied Physics Department, Cinvestav Unidad Merida, Km 6 Ant., Carretera a Progreso, A.P. 73, C.P. 97310 Merida, Yucatan (Mexico); Gamboa, Fidel; Sosa, Victor [Applied Physics Department, Cinvestav Unidad Merida, Km 6 Ant., Carretera a Progreso, A.P. 73, C.P. 97310 Merida, Yucatan (Mexico)

    2010-12-15

    The temperature and field dependence of harmonics in voltage V{sub n}=V{sub n}{sup '}-iV{sub n}{sup ''} using the screening technique have been measured for YBa{sub 2}Cu{sub 3}O{sub 7-{delta}} superconducting thin films. Using the Sun model we obtained the curves for the temperature-dependent critical current density J{sub c}(T). In addition, we applied the criterion proposed by Acosta et al. to compute J{sub c}(T). Also, we made used of the empirical law J{sub c{proportional_to}}(1-T/T{sub c}){sup n} as an input in our calculations to reproduce experimental harmonic generation up to the fifth harmonic. We found that most models fit well the fundamental voltage but higher harmonics are poorly reproduced. Such behavior suggests the idea that higher harmonics contain information concerning complex processes like flux creep or thermally assisted flux flow.

  2. Inhomogeneity effects in HTS coated conductors used as resistive FCLs in medium voltage grids

    Science.gov (United States)

    Colangelo, Daniele; Dutoit, Bertrand

    2012-09-01

    For resistive fault current limiters (RFCLs) based on high temperature superconducting coated conductors (HTS-CCs), inhomogeneity, in terms of critical current and geometrical imperfections such as stabilizer and substrate thicknesses, plays a very important role and it may limit the penetration of such devices into the electrical market. This paper presents an electrothermal model, developed in SimPowerSystem™, able to describe the transient response of HTS-CC candidates with different degrees of inhomogeneity, both in terms of critical current and of stabilizer thickness. Critical current inhomogeneity has been modeled with Gaussian distributions. The layer thicknesses used in the simulations have been chosen by fitting the temperature dependence of real tape resistances. Our approach considers relative inhomogeneity positions as well as thermal conduction along the HTS-CC length. The model is tuned using experimental measurements made on ReBaCuO coated conductors. A new dynamical thermal calibration of the model is proposed using finite element method calculations. Inhomegeneity effects with different possible faults (e.g. three phase and single phase short-circuit) are presented.

  3. LOW VOLTAGE NETWORKS INSULATION MONITORING WITH TWO AND THREE VOLTMETER READOUTS METHODS

    Directory of Open Access Journals (Sweden)

    P. Olszowiec

    2016-11-01

    Full Text Available Purpose. In the paper there are described methods of two and three voltmeter readouts for insulation resistance periodic measurement in live DC and AC/DC IT networks. A new measuring method for AC/DC networks is proposed. Application of a novel algorithm for shortening of measurement cycle is explained. Methodology. All methods of two and three voltmeter readouts consist in connection of a resistor and measurement of mean value of network’s fixed point-to-ground voltages. Results. A new algorithm implemented in KDZ-3 device enables determination of steady-state voltage of a DC network’s pole much faster than in other exploited systems. Originality. In author’s modification of two voltmeter readouts method, line-to-ground voltage mean value is measured at AC side of AC/DC network. This innovation has not been applied for implementation of periodic insulation monitoring in AC/DC IT networks yet. Practical value. The use of author’s innovation will allow to execute measurements at AC side of AC/DC IT networks which might be necessary if rectifier’s output circuits are unavailable. Shortening of measurement cycle duration of two or three voltmeter readouts method’s is of great importance in networks with high capacitance.

  4. High-voltage switchgear and controlgear part 200 : AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV

    CERN Document Server

    International Electrotechnical Commission. Geneva

    2011-01-01

    Specifies requirements for factory-assembled metal-enclosed switchgear and controlgear for alternating current of rated voltages above 1 kV and up to and including 52 kV for indoor and outdoor installation, and for service frequencies up to and including 60 Hz. Enclosures may include fixed and removable components and may be filled with fluid (liquid or gas) to provide insulation. This standard defines several types of metal enclosed switchgear and controlgear which differ due to - the consequences on network service continuity in case of maintenance on the switchgear and controlgear; - the need and convenience of maintenance of the equipment. For metal-enclosed switchgear and controlgear containing gas-filled compartments, the design pressure is limited to a maximum of 300 kPa (relative pressure). Metal-enclosed switchgear and controlgear for special use, for example, in flammable atmospheres, in mines or on board ships, may be subject to additional requirements. Components contained in metal-enclosed switch...

  5. High-voltage switchgear and controlgear part 200 : AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV

    CERN Document Server

    International Electrotechnical Commission. Geneva

    2003-01-01

    Specifies requirements for factory-assembled metal-enclosed switchgear and controlgear for alternating current of rated voltages above 1 kV and up to and including 52 kV for indoor and outdoor installation, and for service frequencies up to and including 60 Hz. Enclosures may include fixed and removable components and may be filled with fluid (liquid or gas) to provide insulation. This standard defines several types of metal enclosed switchgear and controlgear which differ due to - the consequences on network service continuity in case of maintenance on the switchgear and controlgear; - the need and convenience of maintenance of the equipment. For metal-enclosed switchgear and controlgear containing gas-filled compartments, the design pressure is limited to a maximum of 300 kPa (relative pressure). Metal-enclosed switchgear and controlgear for special use, for example, in flammable atmospheres, in mines or on board ships, may be subject to additional requirements. Components contained in metal-enclosed switch...

  6. Effects of (−-Gallocatechin-3-Gallate on Tetrodotoxin-Resistant Voltage-Gated Sodium Channels in Rat Dorsal Root Ganglion Neurons

    Directory of Open Access Journals (Sweden)

    Jian-Min Jiang

    2013-05-01

    Full Text Available The (−-gallocatechin-3-gallate (GCG concentration in some tea beverages can account for as much as 50% of the total catechins. It has been shown that catechins have analgesic properties. Voltage-gated sodium channels (Nav mediate neuronal action potentials. Tetrodotoxin inhibits all Nav isoforms, but Nav1.8 and Nav1.9 are relatively tetrodotoxin-resistant compared to other isoforms and functionally linked to nociception. In this study, the effects of GCG on tetrodotoxin-resistant Na+ currents were investigated in rat primary cultures of dorsal root ganglion neurons via the whole-cell patch-clamp technique. We found that 1 μM GCG reduced the amplitudes of peak current density of tetrodotoxin-resistant Na+ currents significantly. Furthermore, the inhibition was accompanied by a depolarizing shift of the activation voltage and a hyperpolarizing shift of steady-state inactivation voltage. The percentage block of GCG (1 μM on tetrodotoxin-resistant Na+ current was 45.1% ± 1.1% in 10 min. In addition, GCG did not produce frequency-dependent block of tetrodotoxin-resistant Na+ currents at stimulation frequencies of 1 Hz, 2 Hz and 5 Hz. On the basis of these findings, we propose that GCG may be a potential analgesic agent.

  7. Regulation of the forming process and the set voltage distribution of unipolar resistance switching in spin-coated CoFe2O4 thin films.

    Science.gov (United States)

    Mustaqima, Millaty; Yoo, Pilsun; Huang, Wei; Lee, Bo Wha; Liu, Chunli

    2015-01-01

    We report the preparation of (111) preferentially oriented CoFe2O4 thin films on Pt(111)/TiO2/SiO2/Si substrates using a spin-coating process. The post-annealing conditions and film thickness were varied for cobalt ferrite (CFO) thin films, and Pt/CFO/Pt structures were prepared to investigate the resistance switching behaviors. Our results showed that resistance switching without a forming process is preferred to obtain less fluctuation in the set voltage, which can be regulated directly from the preparation conditions of the CFO thin films. Therefore, instead of thicker film, CFO thin films deposited by two times spin-coating with a thickness about 100 nm gave stable resistance switching with the most stable set voltage. Since the forming process and the large variation in set voltage have been considered as serious obstacles for the practical application of resistance switching for non-volatile memory devices, our results could provide meaningful insights in improving the performance of ferrite material-based resistance switching memory devices.

  8. 基于 DSP 的逆变交流电阻焊电源控制%Control of Power Source for AC Inverter Resistance Welding on the Basis of DSP

    Institute of Scientific and Technical Information of China (English)

    曹彪; 李海波; 庞少辉

    2015-01-01

    常用的工频电阻焊机输出不连续的类正弦交流波形,由于电流过零时间长,同等功率下电流峰值过大,造成焊接时工件加热不连续,易产生飞溅,针对上述问题,设计了一种基于数字信号处理器(DSP)的逆变交流控制系统。该系统以 DSP 为控制核心,包括信息检测、脉宽调制(PWM)输出控制、人机交互、输入输出(I /O)接口、故障检测等电路和相应的控制软件。系统采用 PWM控制方式调节焊接变压器的初级电压,实现了大范围电流调节条件下较为连续的输出;具有电流、电压、功率3种反馈控制模式和多种频率选择,在每半个周期内实现快速反馈调节,提高了控制精度,改善了交流电阻焊机的工艺适应性。%Single-phase AC resistance welder provides alternating current similar to sine-wave.Due to the long zero-crossing time and high peak current,welding heating becomes discontinuous and splash occurs easily.In order to solve these problems,a control system for AC resistance welding,which takes DSP(Digital Signal Processor)as the controlling core and is composed of information detection,PWM (Pulse Width Modulation)output control,human-computer interaction,I /O (Input/Output)interface and fault detection circuits,is developed,and the correspond-ing software is also designed to assure system function.By employing PWMcontrol to adjust the primary voltage of welding transformer,a relative continuous output in wide current range is ensured.The control system possesses three feedback control modes respectively in terms of current,voltage and power,provides several output frequen-cies,and implements quick and stable output control in half a period.Thus,both high control precision and adaptive welding process can be achieved.

  9. Capacitor Voltages Measurement and Balancing in Flying Capacitor Multilevel Converters Utilizing a Single Voltage Sensor

    DEFF Research Database (Denmark)

    Farivar, Glen; Ghias, Amer M. Y. M.; Hredzak, Branislav

    2017-01-01

    This paper proposes a new method for measuring capacitor voltages in multilevel flying capacitor (FC) converters that requires only one voltage sensor per phase leg. Multiple dc voltage sensors traditionally used to measure the capacitor voltages are replaced with a single voltage sensor at the ac...... side of the phase leg. The proposed method is subsequently used to balance the capacitor voltages using only the measured ac voltage. The operation of the proposed measurement and balancing method is independent of the number of the converter levels. Experimental results presented for a five-level FC...

  10. Suppression of endurance degradation by applying constant voltage stress in one-transistor and one-resistor resistive random access memory

    Science.gov (United States)

    Su, Yu-Ting; Chang, Ting-Chang; Tsai, Tsung-Ming; Chang, Kuan-Chang; Chu, Tian-Jian; Chen, Hsin-Lu; Chen, Min-Chen; Yang, Chih-Cheng; Huang, Hui-Chun; Lo, Ikai; Zheng, Jin-Cheng; Sze, Simon M.

    2017-01-01

    In this letter we demonstrate an operation method that effectively suppresses endurance degradation. After many operations, the off-state of resistance random access memory (RRAM) degrades. This degradation is caused by reduction of active oxygen ions participating in the set process, as determined by current fitting of current-voltage (I-V) curves obtained from the endurance test between the interval of seventy to one hundred million operations. To address this problem, we propose the application of constant voltage stress after every five million operations during the endurance test. The experimental result shows that this method can maintain oxygen ions at the proper depth in the electrode and improve RRAM reliability.

  11. Temperature influence and reset voltage study of bipolar resistive switching behaviour in ZrO2 thin films

    Indian Academy of Sciences (India)

    Ying Li; Gaoyang Zhao; Jian Su; Erfeng Shen; Yang Ren

    2014-05-01

    We have fabricated ZrO2 thin films by sol–gel deposition and annealed them at 300, 500 and 700 °C. Reproducible - curves can be obtained for the device Cu/ZrO2/ATO which is measured at room temperature (300 K). During the RESET operation, L and H values can be controlled by the RESET voltage. Moreover, the Cu/ZrO2/ATO device which the ZrO2 thin film annealed at 300 °C can be measured as resistive switching sweeps at 200, 100 and 50 K. It was found that the ratio of off/on reduced when the measured temperature decreased. When the - measurement temperature decreases, on decreases obviously which is typical for electronic transportation in a Cu metal. It is indicated that the Cu metallic conduction filament has been formed in the ZrO2 films. Besides, the microstructure by high resolution transmission electrical microscopy (HRTEM) was also investigated.

  12. Sulfone-carbonate ternary electrolyte with further increased capacity retention and burn resistance for high voltage lithium ion batteries

    Science.gov (United States)

    Xue, Leigang; Lee, Seung-Yul; Zhao, Zuofeng; Angell, C. Austen

    2015-11-01

    Safety and high energy density are the two focus issues for current lithium ion batteries. For safety, it has been demonstrated that sulfone electrolytes are much less flammable than the prevailing all-carbonate type, and they are also promising for high voltage batteries due to the high oxidization resistance. However, the high melting points and viscosities greatly restricted their application. Based on our previous work on use of fluidity-enhancing cosolvents to make binary sulfone-carbonate electrolytes, we report here a three-component system that is more conductive and should be even less flammable while additionally having better low temperature stability. The conductivity-viscosity relations have been determined for this electrolyte and are comparable to those of the "standard" carbonate electrolyte. The additional component also produces much improved capacity retention for the LiNi0.5Mn1.5O4 cathode. As with carbonate electrolytes, increase of temperature to 55 °C leads to rapid capacity decrease during cycling, but the capacity loss is due to the salt, not the solvent. The high discharge capacity observed at 25 °C when LiBF4 replaces LiPF6, is fully retained at 55 °C.

  13. Regression Models Using Fully Discharged Voltage and Internal Resistance for State of Health Estimation of Lithium-Ion Batteries

    Directory of Open Access Journals (Sweden)

    Kuo-Hsin Tseng

    2015-04-01

    Full Text Available Accurate estimation of lithium-ion battery life is essential to assure the reliable operation of the energy supply system. This study develops regression models for battery prognostics using statistical methods. The resultant regression models can not only monitor a battery’s degradation trend but also accurately predict its remaining useful life (RUL at an early stage. Three sets of test data are employed in the training stage for regression models. Another set of data is then applied to the regression models for validation. The fully discharged voltage (Vdis and internal resistance (R are adopted as aging parameters in two different mathematical models, with polynomial and exponential functions. A particle swarm optimization (PSO process is applied to search for optimal coefficients of the regression models. Simulations indicate that the regression models using Vdis and R as aging parameters can build a real state of health profile more accurately than those using cycle number, N. The Monte Carlo method is further employed to make the models adaptive. The subsequent results, however, show that this results in an insignificant improvement of the battery life prediction. A reasonable speculation is that the PSO process already yields the major model coefficients.

  14. Improvement of the voltage-controlled negative resistance of a porous silicon emitter using cathode reduction and electro-pretreatment

    Science.gov (United States)

    He, Li; Zhang, Xiaoning; Wang, Wenjiang; Zhao, Xiaoning

    2016-09-01

    A new composite treatment method combining cathode reduction (CR) and electro-pretreatment (EP) is proposed to improve the voltage-controlled negative resistance (VCNR) of porous silicon (PS) emitters. Four groups of PS emitters were treated, with nothing, CR, EP, and a combination of CR and EP, during different preparation stages. The experimental results indicate that both CR and EP improved the VCNR property and the emission characteristics of the PS emitter. The most favorable results occurred for the electron emitter treated with a combination of CR-EP. A peak-to-valley current ratio of 1.06 and an emission current density of 150 µA cm-2, which are the lowest value and approximately twice that of other samples, respectively, were obtained. In addition, the operating stability of the PS emitter also improved significantly compared with the two methods alone. Scanning electron microscopy, atomic force microscopy, and energy dispersive x-ray spectrometry results demonstrate that the improvements of the VCNR and the emission characteristics of PS emitters are due to the content variation of defects, impurities, and unstable microstructures in the PS layer under the influence of CR and EP. The mechanism of VCNR behavior is explained by a proposed energy band model, which is consistent with the experimental results.

  15. Sensorless operation of surface mount permanent magnet AC (PMAC) motors

    Energy Technology Data Exchange (ETDEWEB)

    Toliyat, H.A.; Rahman, K.M.; Shet, D.S.

    1999-12-01

    A sensorless field oriented control scheme for surface mount permanent magnet ac (PMAC) motor with split phase stator windings is presented. This motor is obtained by splitting the phase windings of a conventional three phase motor. The six-phase motor, however is run as a three-phase motor by connecting the split phase stator windings in series, while the taps are made available for voltage measurements. By measuring the terminal voltages and the line currents, absolute position of the permanent magnet ac motor driven by a current regulated PWM inverter with a hysteresis controller is estimated. The estimated position information is independent of the stator resistance, thus this scheme is even applicable at low speeds. Results are presented to show the effectiveness of the new controller, and it is also shown that the position error is negligible.

  16. Thermal instability and current-voltage scaling in superconducting fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Zeimetz, B [Department of Materials Science and Metallurgy, Cambridge University, Pembroke Street, Cambridge CB1 3QZ (United Kingdom); Tadinada, K [Department of Engineering, Cambridge University, Trumpington Road, Cambridge CB2 1PZ (United Kingdom); Eves, D E [Department of Engineering, Cambridge University, Trumpington Road, Cambridge CB2 1PZ (United Kingdom); Coombs, T A [Department of Engineering, Cambridge University, Trumpington Road, Cambridge CB2 1PZ (United Kingdom); Evetts, J E [Department of Materials Science and Metallurgy, Cambridge University, Pembroke Street, Cambridge CB1 3QZ (United Kingdom); Campbell, A M [Department of Engineering, Cambridge University, Trumpington Road, Cambridge CB2 1PZ (United Kingdom)

    2004-04-01

    We have developed a computer model for the simulation of resistive superconducting fault current limiters in three dimensions. The program calculates the electromagnetic and thermal response of a superconductor to a time-dependent overload voltage, with different possible cooling conditions for the surfaces, and locally variable superconducting and thermal properties. We find that the cryogen boil-off parameters critically influence the stability of a limiter. The recovery time after a fault increases strongly with thickness. Above a critical thickness, the temperature is unstable even for a small applied AC voltage. The maximum voltage and maximum current during a short fault are correlated by a simple exponential law.

  17. AC/RF Superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Ciovati, Gianluigi [JLAB

    2015-02-01

    This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

  18. Estimation of Transformer Parameters and Loss Analysis for High Voltage Capacitor Charging Application

    DEFF Research Database (Denmark)

    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......) winding has to be estimated accurately. This paper analyzes the following losses of bi-directional flyback converter namely switching loss, conduction loss, gate drive loss, transformer core loss, and snubber loss, etc. Iterative analysis of transformer parameters viz., AC resistance, leakage inductance...

  19. System for improving measurement accuracy of transducer by measuring transducer temperature and resistance change using thermoelectric voltages

    Science.gov (United States)

    Anderson, Karl F. (Inventor); Parker, Allen R., Jr. (Inventor)

    1993-01-01

    A constant current loop measuring system measures a property including the temperature of a sensor responsive to an external condition being measured. The measuring system includes thermocouple conductors connected to the sensor, sensing first and second induced voltages responsive to the external condition. In addition, the measuring system includes a current generator and reverser generating a constant current, and supplying the constant current to the thermocouple conductors in forward and reverse directions generating first and second measured voltages, and a determining unit receiving the first and second measured voltages from the current generator and reverser, and determining the temperature of the sensor responsive to the first and second measured voltages.

  20. GaAs/Ge solar cell AC parameters at different temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, R. Anil; Suresh, M.S. [ISRO Satellite centre, ISRO, Bangalore 560 017 (India); Nagaraju, J. [Department of Instrumentation, Indian Institute of Science, Bangalore 560 012 (India)

    2003-05-15

    The AC parameters of Gallium Arsenide (GaAs/Ge) solar cell were measured at different cell temperatures (198-348K) by varying the cell bias voltage (forward and reverse) under dark condition using impedance spectroscopy technique. It was found that the cell capacitance increases with the cell temperature where as the cell resistance decreases, at any bias voltage. The measured cell parameters were used to calculate the intrinsic concentration of electron-hole pair, cell material relative permittivity and its band gap energy. The diode factor and the cell dynamic resistance at the corresponding maximum power point decrease with the cell temperature.

  1. 感应电动机交流相控调压下的损耗分析%Loss Analysis on the Induction Motor Under Phase-control AC Voltage Regulation

    Institute of Scientific and Technical Information of China (English)

    李文志

    2015-01-01

    The dynamic mathematic model based upon space vector coordinate system was established to study the change of energy loss of the induction motor under phase-control AC voltage regulation. Change intension of various loss of the motor under different firing angle was achieved by means of MATLAB simulation, especially the copper loss of the stator and rotor as well as the iron loss. Data of experiments verified correctness of the simulation results.%建立基于空间矢量坐标系的动态数学模型,研究相控调压技术下感应电机的能耗变化。并通过MATLAB仿真得到电机在不同触发角下的各项损耗变化趋势,特别是定、转子铜损耗和铁损耗。实验数据验证了仿真结果的正确性。

  2. High Voltage Resistive Divider Based on Cast Microwire in Glass Insulation on 6–24 kV Alternating Current of Commercial Frequency.

    Directory of Open Access Journals (Sweden)

    Juravleov A.

    2008-12-01

    Full Text Available It is presented the analysis and description of the construction of the high voltage resistive divider on the base of cast microwire in glass insulation on 6–24 kV alternating current of commercial frequency. It is presented the procedure of compensation of frequency error during the process of fabrication of divides and results of tests of the sample model of the divider as well.

  3. Agronomic performance, chromosomal stability and resistance to velvetbean caterpillar of transgenic soybean expressing cry1Ac gene Performance agronômica, estabilidade cromossômica e resistência à lagarta-da-soja em soja transgênica que expressa o gene cry1Ac

    Directory of Open Access Journals (Sweden)

    Milena Schenkel Homrich

    2008-07-01

    Full Text Available The objective of this work was to analyze the agronomic performance and chromosomal stability of transgenic homozygous progenies of soybean [Glycine max (L. Merrill.], and to confirm the resistance of these plants against Anticarsia gemmatalis. Eleven progenies expressing cry1Ac, hpt and gusA genes were evaluated for agronomic characteristics in relation to the nontransformed parent IAS 5 cultivar. Cytogenetical analysis was carried out on transgenic and nontransgenic plants. Two out of the 11 transgenic progenies were also evaluated, in vitro and in vivo, for resistance to A. gemmatalis. Two negative controls were used in resistance bioassays: a transgenic homozygous line, containing only the gusA reporter gene, and nontransgenic 'IAS 5' plants. The presence of cry1Ac transgene affected neither the development nor the yield of plants. Cytogenetical analysis showed that transgenic plants presented normal karyotype. In detached-leaf bioassay, cry1Ac plants exhibited complete efficacy against A. gemmatalis, whereas negative controls were significantly damaged. Whole-plant feeding assay confirmed a very high protection of cry1Ac against velvetbean caterpillar, while nontransgenic 'IAS 5' plants and homozygous gusA line exhibited 56.5 and 71.5% defoliation, respectively. The presence of cry1Ac transgene doesn't affect the majority of agronomic traits (including yield of soybean and grants high protection against A. gemmatalis.O objetivo deste trabalho foi analisar a performance agronômica e a estabilidade cromossômica de progênies transgênicas homozigotas de soja [Glycine max (L. Merrill.], e confirmar a resistência dessas plantas a Anticarsia gemmatalis. Onze progênies com expressão dos genes cry1Ac, hpt e gusA foram avaliadas quanto às características agronômicas, em relação à cultivar parental IAS 5 não transformada. Análises citogenéticas foram realizadas em plantas transgênicas e não transgênicas. Duas das 11 prog

  4. AC plasma anemometer—characteristics and design

    Science.gov (United States)

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

    2015-08-01

    The characteristics and design of a high-bandwidth flow sensor that uses an AC glow discharge (plasma) as the sensing element is presented. The plasma forms in the air gap between two protruding low profile electrodes attached to a probe body. The output from the anemometer is an amplitude modulated version of the AC voltage input that contains information about the mean and fluctuating velocity components. The anemometer circuitry includes resistance and capacitance elements that simulate a dielectric-barrier to maintain a diffuse plasma, and a constant-current feedback control that maintains operation within the desired glow discharge regime over an extended range of air velocities. Mean velocity calibrations are demonstrated over a range from 0 to 140 m s-1. Over this velocity range, the mean output voltage varied linearly with air velocity, providing a constant static sensitivity. The effect of the electrode gap and input AC carrier frequency on the anemometer static sensitivity and dynamic response are investigated. Experiments are performed to compare measurements obtained with a plasma sensor operating at two AC carrier frequencies against that of a constant-temperature hot-wire. All three sensors were calibrated against the same known velocity reference. An uncertainty based on the standard deviation of the velocity calibration fit was applied to the mean and fluctuating velocity measurements of the three sensors. The motivation is not to replace hot-wires as a general measurement tool, but rather as an alternative to hot-wires in harsh environments or at high Mach numbers where they either have difficulty in surviving or lack the necessary frequency response.

  5. The architecture design of a 2mW 18-bit high speed weight voltage type DAC based on dual weight resistance chain

    Institute of Scientific and Technical Information of China (English)

    Chen Qixing; Luo Qiyu

    2013-01-01

    At present,the architecture of a digital-to-analog converter (DAC) in essence is based on the weight current,and the average value of its D/A signal current increases in geometric series according to its digital signal bits increase,which is 2n-1 times of its least weight current.But for a dual weight resistance chain type DAC,by using the weight voltage manner to D/A conversion,the D/A signal current is fixed to chain current Icha; it is only 1/2n-1 order of magnitude of the average signal current value of the weight current type DAC.Its principle is:n pairs dual weight resistances form a resistance chain,which ensures the constancy of the chain current; if digital signals control the total weight resistance from the output point to the zero potential point,that could directly control the total weight voltage of the output point,so that the digital signals directly turn into a sum of the weight voltage signals; thus the following goals are realized:(1) the total current is less than 200 μA; (2) the total power consumption is less than 2 mW; (3) an 18-bit conversion can be realized by adopting a multi-grade structure; (4) the chip area is one order of magnitude smaller than the subsection current-steering type DAC; (5) the error depends only on the error of the unit resistance,so it is smaller than the error of the subsection current-steering type DAC;(6) the conversion time is only one action time of switch on or off,so its speed is not lower than the present DAC.

  6. New lightning current resistant low voltage limiting device for DC railway systems; Neue blitzstromtragfaehige Niederspannungsbegrenzungseinrichtung zum Potenzialschutz von Gleichstrombahnsystemen

    Energy Technology Data Exchange (ETDEWEB)

    Rocks, A.; Hinrichsen, V. [Technische Univ. Darmstadt (Germany). Fachgebiet Hochspannungstechnik; Richter, B. [ABB Schweiz AG, Wettingen (Switzerland); Zayer, H. [ESN Bahngeraete GmbH, Mannheim (Germany)

    2007-07-01

    In dc railway systems, low voltage limiters are applied to limit potential rises in case of failures by forming a permanent short-circuit between return circuit and Earth. These devices can usually carry only moderate lightning currents without permanent failure. In this contribution, a new concept is introduced which provides personal as well as equipment protection by combining a surge arrester and a low voltage limiter in a suited way. (orig.)

  7. CMOS temperature sensor using a resistively degenerated common-source amplifier biased by an adjustable proportional-to-absolute-temperature voltage

    Science.gov (United States)

    Wang, Ruey-Lue; Fu, Chien-Cheng; Yu, Chi; Hao, Yi-Fan; Shi, Jian-Liang; Lin, Chen-Fu; Liao, Hsin-Hao; Tsai, Hann-Huei; Juang, Ying-Zong

    2014-01-01

    A high-linearity CMOS temperature sensor with pulse output is presented. The temperature core is a resistively degenerated common-source amplifier which gate is biased by a proportional-to-absolute-temperature (PTAT) voltage generator. The source resistor is made of polysilicon which resistance has a PTAT characteristic. The current flowing through the resistor exhibits a PTAT characteristic with high linearity of 99.99% at least for a temperature range from 0 to 125 °C. The PTAT voltage generator can be adjusted by a bias voltage Vb and hence the PTAT current can also be adjusted by the Vb. The PTAT current is mirrored to an added current controlled oscillator which output pulse frequencies also exhibit a PTAT characteristic. For the chip using the 0.35 µm process, the plots of measured pulse frequencies against temperature exhibit the sensitivity of 2.30 to 2.24 kHz/°C with linearity of more than 99.99% at the Vb of 1 to 1.2 V.

  8. 带弧垂特高压交流输电线路的电磁剂量学分析%Analysis of electromagnetic dosimetry by ultra high voltage AC transmission line with belt sag

    Institute of Scientific and Technical Information of China (English)

    张利航; 逯迈; 陈小强; 侯立伟

    2016-01-01

    采用Comsol仿真软件和人体模型计算分析倒三角较贴近实际的带弧垂特高压交流输电线路对人体产生的电场效应,并与理想直导线的结果进行对比。结果表明,人体以及人体附近电场和感应电流分布不均匀,体外电场最大值集中于人体头部表面上方,关节连接处和端部的电场、感应电流密度较大。带弧垂特高压输电线路在人体各组织产生的电场和感应电流密度均较理想笔直导线线路下高约17%~19%;与国际非电离辐射防护委员会(International commission on non-ionizing radiation protection, ICNIRP)导则限值相比较,电场强度无论是对专业人员还是普通民众均在 ICNIRP 导则限值范围内;而感应电流密度除人体腿部下部、头皮与颈部连接处附近的略高于ICNIRP导则中普通民众的限值外,其他均在ICNIRP导则限值范围内。两种类型特高压输电线路所产生的电磁辐射对专业人员是安全的,对普通民众应注意适当的防护。%The aim is to investigate the electric field effect produced by the ultra high voltage (UHV) AC transmission lines with belt sag on the human body. A simulation software named Comsol and a human body model were used to calculate and analyze the electric field effect caused by the nabla UHV AC transmission lines closely to the reality, and then the result was compared with the one produced by ideal straight lines. The results indicated that in the human and the near-field region, the distribution of electric field and induced current was nonuniform. The maximum electric field focused on the above region of human head surface. The value of electric field intensity and  induced current density in the joints of the body were high. Below the actual and ideal straight UHV transmission lines, the electric field intensity and induced current density produced by the belt sag wire in all tissues including central nervous system of human was 17

  9. Analyzing of Dynamic Voltage Restorer in Series Compensation Voltage

    Directory of Open Access Journals (Sweden)

    Naser Parhizgar

    2012-02-01

    Full Text Available The Dynamic Voltage Restorer (DVR is a series-connected compensator to generate a controllable voltage to against the short-term voltage disturbances. The technique of DVR is an effective and cost competitive approach to improve voltage quality at the load side. This study presents a single-phase and threephase DVR system with reduced switch-count topology to protect the sensitive load against abnormal voltage conditions. Most basic function, the DVR configuration consist of a two level Voltage Source Converter (VSC, a dc energy storage device, a coupling transformer Connected in shunt with the ac system This study presents the application of Dynamic Voltage Restorer (DVR on power distribution systems for mitigation of voltage sag at critical loads. DVR is one of the compensating types of custom power devices. The DVR, which is based on forced-commutated Voltage Source Converter (VSC has been proved suitable for the task of compensating voltage sags/swells. Simulation results are presented to illustrate and understand the performances of DVR in supporting load voltages under voltage sags/swells conditions.

  10. Voltage dips ride-through capability. Model validation of a resistance-commutated rotor wind turbine generator from in-field testing results

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Guillen, Miguel A.; Paz Comech, M.; Ruiz Guillen, Javier; Giraut Ruso, Elizabeth; Garcia-Gracia, Miguel

    2009-07-01

    The present wind energy penetration into the electrical network has forced system operators to adapt their Grid Codes to this new generation, preventing an unacceptable effect on the system safety and reliability. There are several wind turbine models that can be used to study the effects of voltage dips and the corresponding wind turbine responses but these models need to be validated by comparing their results with the data obtained during field tests. This paper describe the process followed for the validation of a Resistance-Commutated rotor wind turbine generator from in-field testing results according to the Spanish procedure for verification, validation and certification of the requirements of the P.O. 12.3 on the response of wind farms in the event of voltage dips. (orig.)

  11. Experimental validation of a high voltage pulse measurement method.

    Energy Technology Data Exchange (ETDEWEB)

    Cular, Stefan; Patel, Nishant Bhupendra; Branch, Darren W.

    2013-09-01

    This report describes X-cut lithium niobates (LiNbO3) utilization for voltage sensing by monitoring the acoustic wave propagation changes through LiNbO3 resulting from applied voltage. Direct current (DC), alternating current (AC) and pulsed voltage signals were applied to the crystal. Voltage induced shift in acoustic wave propagation time scaled quadratically for DC and AC voltages and linearly for pulsed voltages. The measured values ranged from 10 - 273 ps and 189 ps 2 ns for DC and non-DC voltages, respectively. Data suggests LiNbO3 has a frequency sensitive response to voltage. If voltage source error is eliminated through physical modeling from the uncertainty budget, the sensors U95 estimated combined uncertainty could decrease to ~0.025% for DC, AC, and pulsed voltage measurements.

  12. Border Collision of Three-Phase Voltage-Source Inverter System with Interacting Loads

    Science.gov (United States)

    Li, Zhen; Liu, Bin; Li, Yining; Wong, Siu-Chung; Liu, Xiangdong; Huang, Yuehui

    As a commercial interface, three-phase voltage-source inverters (VSI) are commonly equipped for energy conversion to export DC power from most distributed generation (DG) to the AC utility. Not only do voltage-source converters take charge of converting the power to the loads but support the grid voltage at the point of common connection (PCC) as well, which is dependent on the condition of the grid-connected loads. This paper explores the border collision and its interacting mechanism among the VSI, resistive interacting loads and grids, which manifests as the alternating emergence of the inverting and rectifying operations, where the normal operation is terminated and a new one is assumed. Their mutual effect on the power quality under investigation will cause the circuital stability issue and further deteriorate the voltage regulation capability of VSI by dramatically raising the grid voltage harmonics. It is found in a design-oriented view that the border collision operation will be induced within the unsuitable parameter space with respect to transmission lines of AC grid, resistive loads and internal resistance of VSI. The physical phenomenon is also identified by the theoretical analysis. With numerical simulations for various circuit conditions, the corresponding bifurcation boundaries are collected, where the stability of the system is lost via border collision.

  13. Using resistant prey demonstrates that Bt plants producing Cry1Ac, Cry2Ab, and Cry1F have no negative effects on Geocoris punctipes and Orius insidiosus.

    Science.gov (United States)

    Tian, Jun-Ce; Long, Li-Ping; Wang, Xiang-Ping; Naranjo, Steven E; Romeis, Jörg; Hellmich, Richard L; Wang, Ping; Shelton, Anthony M

    2014-02-01

    Geocoris punctipes (Say) and Orius insidiosus (Say) are generalist predators found in a wide range of crops, including cotton (Gossypium hirsutum L.) and maize (Zea mays L.), where they provide important biological control services by feeding on an array of pests, including eggs and small larvae of caterpillars. A high percentage of cotton and maize in the United States and several other countries are transgenic cultivars that produce one or more of the insecticidal Cry proteins of Bacillus thuringiensis Berliner (Bt). Here we quantify effects of three Cry proteins on the life history of these predators over two generations when they are exposed to these Cry proteins indirectly through their prey. To eliminate the confounding prey quality effects that can be introduced by Bt-susceptible prey, we used Cry1Ac/Cry2Ab-resistant Trichoplusia ni (Hübner) and Cry1 F-resistant Spodoptera frugiperda (J.E. Smith) in a series of tri-trophic studies. Survival, development, adult mass, fecundity, and fertility were similar when predators consumed larvae feeding on Cry1Ac/Cry2Ab cotton or Cry1 F maize compared with prey feeding on isogenic or near-isogenic cotton or maize. Repeated exposure of the same initial cohort over a second generation also resulted in no differences in life-history traits when feeding on non-Bt- or Bt-fed prey. Enzyme-linked immunosorbent assay showed that predators were exposed to Bt Cry proteins from their prey and that these proteins became increasingly diluted as they moved up the food chain. Results show a clear lack of effect of three common and widespread Cry proteins on these two important predator species. The use of resistant insects to eliminate prey quality effects provides a robust and meaningful assessment of exposure and hazard.

  14. Studying Voltage Transformer Ferroresonance

    Directory of Open Access Journals (Sweden)

    Hamid Radmanesh

    2012-09-01

    Full Text Available This study studies the effect of Circuit Breaker Shunt Resistance (CBSR, Metal Oxide Vaistor (MOV and Neutral earth Resistance (NR on the control of ferroresonance in the voltage transformer. It is expected that NR can controlled ferroresonance better than MOV and CBSR. Study has been done on a one phase voltage transformer rated 100 VA, 275 kV. The simulation results reveal that considering the CBSR and MOV exhibits a great mitigating effect on ferroresonance overvoltages, but these resistances cannot control these phenomena for all range of parameters. By applying NR to the system structure, ferroresonance has been controlled and its amplitude has been damped for all parameters values.

  15. Characterization and functional analysis ofβ-1,3-galactosyltransferase involved in Cry1Ac resistance from Helicoverpa armigera (Hübner)

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-li; LIANG Ge-mei; GAO Xi-wu; CAO Guang-chun; GUO Yu-yuan

    2015-01-01

    Carbohydrate chains are the principal antigens by which Bacil us thuringiensis (Bt) identify receptor proteins. The interaction between the antigen and Bt causes a pore in the membrane of midgut epithelial cel s of insects. Receptor proteins, such as aminopeptidase N and alkaline phosphatase, are glycoproteins. Cadherin is another cel surface receptor protein which has potential glycosylation sites. Glycosyltransferase is very important for the synthesis and modiifcation of receptor proteins. It can indirectly inlfuence the function of Bt. The 1 950 bp ful-length cDNA encodingβ-1,3-galactosyltransferase was cloned from the the midgut of Helicoverpa armigera by degenerative PCR combined with RACE techniques (GAL-Harm, GenBank accession no.:GQ904195.1) with two potential N-glycosylation sites (157NNTI160 and 272NKTL275). Protein sequence alignments revealed that H. armigeraβ-1,3-galactosyltransferase shared high identity withβ-1,3-galactosyltransferase in other insect species. The expression level of theβ-1,3-galactosyltransferase gene in Cry1Ac-resistant H. armigera larvae was 9.2-fold higher than that in susceptible strain. The function ofβ-1,3-galactosyltransferase was investigated using RNAi technique. The result showed Cry1Ac enhanced the toxicity against the siRNA-treated larvae compared with non-siRNA-treated ones, which indicatedβ-1,3-galactosyltransferase played an important role for the insecticidal toxicity of Cry1Ac in H. armigera.

  16. Magnetoresistance and negative differential resistance in Ni/graphene/Ni vertical heterostructures driven by finite bias voltage: a first-principles study

    DEFF Research Database (Denmark)

    Saha, Kamal K.; Blom, Anders; Thygesen, Kristian S.

    2012-01-01

    Using the nonequilibrium Green's function formalism combined with density functional theory, we study finite bias quantum transport in Ni/Grn/Ni vertical heterostructures where n graphene layers are sandwiched between two semi-infinite Ni(111) electrodes. We find that the recently predicted...... differential resistance as the bias voltage is increased from Vb=0 V to Vb≃0.5 V. We confirm that both of these nonequilibrium transport effects hold for different types of bonding of Gr on the Ni(111) surface while maintaining Bernal stacking between individual Gr layers....

  17. Stray voltage mitigation

    Energy Technology Data Exchange (ETDEWEB)

    Jamali, B.; Piercy, R.; Dick, P. [Kinetrics Inc., Toronto, ON (Canada). Transmission and Distribution Technologies

    2008-04-09

    This report discussed issues related to farm stray voltage and evaluated mitigation strategies and costs for limiting voltage to farms. A 3-phase, 3-wire system with no neutral ground was used throughout North America before the 1930s. Transformers were connected phase to phase without any electrical connection between the primary and secondary sides of the transformers. Distribution voltage levels were then increased and multi-grounded neutral wires were added. The earth now forms a parallel return path for the neutral current that allows part of the neutral current to flow continuously through the earth. The arrangement is responsible for causing stray voltage. Stray voltage causes uneven milk production, increased incidences of mastitis, and can create a reluctance to drink water amongst cows when stray voltages are present. Off-farm sources of stray voltage include phase unbalances, undersized neutral wire, and high resistance splices on the neutral wire. Mitigation strategies for reducing stray voltage include phase balancing; conversion from single to 3-phase; increasing distribution voltage levels, and changing pole configurations. 22 refs., 5 tabs., 13 figs.

  18. Resistance switching memory operation using the bistability in current-voltage characteristics of GaN/AlN resonant tunneling diodes

    Science.gov (United States)

    Nagase, Masanori; Takahashi, Tokio; Shimizu, Mitsuaki

    2016-10-01

    Resistance switching memory operations using the bistability in the current-voltage (I-V) characteristics of GaN/AlN resonant tunneling diodes (RTDs) were investigated to realize an ultrafast nonvolatile memory operating at a picosecond time scale. Resistance switching memory operations based on electron accumulation due to intersubband transitions and electron release due to tunneling current were demonstrated with high reproducibility at room temperature when the leakage of electrons accumulating in the quantum well from the deep level in the AlN barrier was suppressed. A nonvolatile memory for the processor core in a normally off computing system is expected to be realized using the bistability in the I-V characteristics of GaN/AlN RTDs.

  19. Cross-resistance of Cry1Ac-resistant Heliocoverpa armigera Hübner%抗Bt棉铃虫种群的交互抗性研究

    Institute of Scientific and Technical Information of China (English)

    卢美光; 芮昌辉; 赵建周; 孟香清

    2000-01-01

    分别用对Cry1Ac抗性达11.6倍的Bt棉叶和Bt粉剂(Btk)汰选棉铃虫(Heliocoverpa armigera)种群(对Btk的抗性指数为5.2倍),测定了其对不同Bt制剂、Bt毒素、化学农药的交互抗性.结果表明:停止汰选后,Bt棉叶汰选种群对Cry1Ac的抗性指数为5.9倍,对Cry1Ac+1C的交互抗性为3.7倍,对Btk的敏感性降低,对Bta、Cry2A无交互抗性;Btk汰选种群对Btk的抗性指数为4.1倍,对Bta、 Cry1Ac、Cry1Ac+1C的交互抗性为2.3、3.1、2.3倍,对Cry2A无交互抗性;两汰选种群对化学农药灭多威、辛硫磷、氯氰菊酯的敏感性均有所增加.

  20. Frequency of alleles conferring resistance to the Bacillus thuringiensis toxins Cry1Ac and Cry2Ab in Australian populations of Helicoverpa punctigera (Lepidoptera: Noctuidae) from 2002 to 2006.

    Science.gov (United States)

    Downes, S; Parker, T L; Mahon, R J

    2009-04-01

    Helicoverpa punctigera and Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) are important pests of field and horticultural crops in Australia. The former is endemic to the continent, whereas the latter is also distributed in Africa and Asia. Although H. armigera rapidly developed resistance to virtually every group of insecticide used against it, there is only one report of resistance to an insecticide in H. punctigera. In 1996 the Australian cotton industry adopted Ingard, which expresses the Bacillus thuringiensis (Bt) toxin gene cry1Ac. In 2004/2005, Bollgard II (which expresses Cry1Ac and Cry2Ab) replaced Ingard and has subsequently been grown on 80% of the area planted to cotton, Gossypium hirsutum L. From 2002/2003 to 2006/2007, F2 screens were used to detect resistance to Cry1Ac or Cry2Ab. We detected no alleles conferring resistance to Cry1Ac; the frequency was < 0.0005 (n = 2,180 alleles), with a 95% credibility interval between 0 and 0.0014. However, during the same period, we detected alleles that confer resistance to Cry2Ab at a frequency of 0.0018 (n = 2,192 alleles), with a 95% credibility interval between 0.0005 and 0.0040. For both toxins, the experiment-wise detection probability was 94%, i.e., if there actually was a resistance allele in any tested lines, we would have detected it 94% of the time. The first isolation of Cry2Ab resistance in H. punctigera was before the widespread deployment of Bollgard II. This finding supports our published notion for H. armigera that alleles conferring resistance to Cry2Ab may be present at detectable frequencies in populations before selection by transgenic crops.

  1. Frequency-controlled voltage regulator

    Science.gov (United States)

    Mclyman, W. T.

    1980-01-01

    Converting input ac to higher frequency reduce size and weight and makes possible unique kind of regulation. Since conversion frequency is above range of human hearing, supply generated on audible noise. It also exploits highfrequency conversion features to regulate its output voltage in novel way. Circuit is inherently short-circuit proof.

  2. Voltage Flicker Mitigation in Electric Arc Furnace using D-STATCOM

    Directory of Open Access Journals (Sweden)

    Deepthisree Madathil

    2014-10-01

    Full Text Available The major power quality issue of voltage flicker has resulted as a serious concern for the customers and heavy power companies. Voltage flicker is an impression of unsteadiness of visual sensation induced by a light source whose luminance fluctuates with time. This phenomenon is experienced when an Electric Arc Furnace (EAF as load is connected to the power system. Flexible AC transmission devices (FACTS devices were gradually utilized for voltage flicker reduction. In this paper the FACTS device of Distribution Static Synchronous Compensator (D-STATCOM is used to serve the purpose of mitigating voltage flickering caused by electric arc furnace load, which is efficiently controlled by Icosɸ control algorithm. The model of electric arc furnace is considered as a current source controlled by a non linear resistance, which had been simulated and performance was analyzed using MATLAB/SIMULINK Software.

  3. Equivalent circuit modeling of a piezo-patch energy harvester on a thin plate with AC-DC conversion

    Science.gov (United States)

    Bayik, B.; Aghakhani, A.; Basdogan, I.; Erturk, A.

    2016-05-01

    As an alternative to beam-like structures, piezoelectric patch-based energy harvesters attached to thin plates can be readily integrated to plate-like structures in automotive, marine, and aerospace applications, in order to directly exploit structural vibration modes of the host system without mass loading and volumetric occupancy of cantilever attachments. In this paper, a multi-mode equivalent circuit model of a piezo-patch energy harvester integrated to a thin plate is developed and coupled with a standard AC-DC conversion circuit. Equivalent circuit parameters are obtained in two different ways: (1) from the modal analysis solution of a distributed-parameter analytical model and (2) from the finite-element numerical model of the harvester by accounting for two-way coupling. After the analytical modeling effort, multi-mode equivalent circuit representation of the harvester is obtained via electronic circuit simulation software SPICE. Using the SPICE software, electromechanical response of the piezoelectric energy harvester connected to linear and nonlinear circuit elements are computed. Simulation results are validated for the standard AC-AC and AC-DC configurations. For the AC input-AC output problem, voltage frequency response functions are calculated for various resistive loads, and they show excellent agreement with modal analysis-based analytical closed-form solution and with the finite-element model. For the standard ideal AC input-DC output case, a full-wave rectifier and a smoothing capacitor are added to the harvester circuit for conversion of the AC voltage to a stable DC voltage, which is also validated against an existing solution by treating the single-mode plate dynamics as a single-degree-of-freedom system.

  4. 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

    Energy Technology Data Exchange (ETDEWEB)

    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.

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

    Science.gov (United States)

    Zhang, Tian; Puthen-Veettil, Binesh; Wu, Lingfeng; Jia, Xuguang; Lin, Ziyun; Yang, Terry Chien-Jen; Conibeer, Gavin; Perez-Wurfl, Ivan

    2015-10-01

    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.

  6. Voltage control of metal-insulator transition and non-volatile ferroelastic switching of resistance in VOx/PMN-PT heterostructures.

    Science.gov (United States)

    Nan, Tianxiang; Liu, Ming; Ren, Wei; Ye, Zuo-Guang; Sun, Nian X

    2014-08-04

    The central challenge in realizing electronics based on strongly correlated electronic states, or 'Mottronics', lies in finding an energy efficient way to switch between the distinct collective phases with a control voltage in a reversible and reproducible manner. In this work, we demonstrate that a voltage-impulse-induced ferroelastic domain switching in the (011)-oriented 0.71Pb(Mg1/3Nb2/3)O3-0.29PbTiO3 (PMN-PT) substrates allows a robust non-volatile tuning of the metal-insulator transition in the VOx films deposited onto them. In such a VOx/PMN-PT heterostructure, the unique two-step electric polarization switching covers up to 90% of the entire poled area and contributes to a homogeneous in-plane anisotropic biaxial strain, which, in turn, enables the lattice changes and results in the suppression of metal-insulator transition in the mechanically coupled VOx films by 6 K with a resistance change up to 40% over a broad range of temperature. These findings provide a framework for realizing in situ and non-volatile tuning of strain-sensitive order parameters in strongly correlated materials, and demonstrate great potentials in delivering reconfigurable, compactable, and energy-efficient electronic devices.

  7. Approaches to building single-stage AC/AC conversion switch-mode audio power amplifiers

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper discusses the possible topologies and promising approaches towards direct single-phase AC-AC conversion of the mains voltage for audio applications. When compared to standard Class-D switching audio power amplifiers with a separate power supply, it is expected that direct conversion...

  8. Specific heat, resistivity, and AC susceptibility of the cubic PrX 2 compounds (X = Pt, Ru, Ir, Rh)

    Science.gov (United States)

    Greidanus, F. J. A. M.; Nieuwenhuys, G. J.; de Jongh, L. J.; Huiskamp, W. J.; Capel, H. W.; Buschow, K. H. J.

    1983-04-01

    Specific-heat, differential-susceptibility and electrical-resistivity measurements on PrX 2 (X = Ir, Pt, Rh, Ru) compounds reveal phase transitions at Tc = 11.2±0.5 K, 7.7±0.5 K, 7.9±0.5 Kand 33.9±0.5 K for X = Ir, Pt, Rh, and Ru, respective ly. From earlier neutron inelastic scattering experiments, the crystalline electric field levels of these compounds have been determined. The specific-heat results are compared with the results of a mean-field calculation, assuming bilinear exchange interactions. The presence of broad secondary maxima in the temperature dependence of the specific heat of PrRh 2, PrRu 2 and especially PrIr 2 can qualitatively be explained by the presence of biquadratic (quadrupolar) interactions. The behaviour of the susceptibility is in agreement with ferromagnetic ordering. The electrical resistivity drops markedly below Tc, and the dϱ/d T versus T curve is similar to that of the specific heat.

  9. Electrothermal ac electro-osmosis

    Science.gov (United States)

    Gagnon, Zachary R.; Chang, Hsueh-Chia

    2009-01-01

    Two ac polarization mechanisms, charge accumulation due to electrode double layer charging and bulk permittivity/conductivity gradients generated by Joule heating, are combined in the double layer by introducing zwitterions to produce a new ac electrokinetic pump with the largest velocity (>1 mm/s) and flow penetration depth (100 μm) reported for low-conductivity fluids. The large fluid velocity is due to a quartic scaling with respect to voltage, as is true of electrothermal flow, but exhibits a clear maximum at a frequency corresponding to the electrode double layer inverse RC time.

  10. Co-occurrence of point mutations in the voltage-gated sodium channel of pyrethroid-resistant Aedes aegypti populations in Myanmar.

    Directory of Open Access Journals (Sweden)

    Hitoshi Kawada

    Full Text Available BACKGROUND: Single amino acid substitutions in the voltage-gated sodium channel associated with pyrethroid resistance constitute one of the main causative factors of knockdown resistance in insects. The kdr gene has been observed in several mosquito species; however, point mutations in the para gene of Aedes aegypti populations in Myanmar have not been fully characterized. The aim of the present study was to determine the types and frequencies of mutations in the para gene of Aedes aegypti collected from used tires in Yangon City, Myanmar. METHODOLOGY/PRINCIPAL FINDINGS: We determined high pyrethroid resistance in Aedes aegypti larvae at all collection sites in Yangon City, by using a simplified knockdown bioassay. We showed that V1016G and S989P mutations were widely distributed, with high frequencies (84.4% and 78.8%, respectively. By contrast, we were unable to detect I1011M (or I1011V or L1014F mutations. F1534C mutations were also widely distributed, but with a lower frequency than the V1016G mutation (21.2%. High percentage of co-occurrence of the homozygous V1016G/S989P mutations was detected (65.7%. Additionally, co-occurrence of homozygous V1016G/F1534C mutations (2.9% and homozygous V1016G/F1534C/S989P mutations (0.98% were detected in the present study. CONCLUSIONS/SIGNIFICANCE: Pyrethroid insecticides were first used for malaria control in 1992, and have since been constantly used in Myanmar. This intensive use may explain the strong selection pressure toward Aedes aegypti, because this mosquito is generally a domestic and endophagic species with a preference for indoor breeding. Extensive use of DDT for malaria control before the use of this chemical was banned may also explain the development of pyrethroid resistance in Aedes aegypti.

  11. Co-occurrence of point mutations in the voltage-gated sodium channel of pyrethroid-resistant Aedes aegypti populations in Myanmar.

    Science.gov (United States)

    Kawada, Hitoshi; Oo, Sai Zaw Min; Thaung, Sein; Kawashima, Emiko; Maung, Yan Naung Maung; Thu, Hlaing Myat; Thant, Kyaw Zin; Minakawa, Noboru

    2014-01-01

    Single amino acid substitutions in the voltage-gated sodium channel associated with pyrethroid resistance constitute one of the main causative factors of knockdown resistance in insects. The kdr gene has been observed in several mosquito species; however, point mutations in the para gene of Aedes aegypti populations in Myanmar have not been fully characterized. The aim of the present study was to determine the types and frequencies of mutations in the para gene of Aedes aegypti collected from used tires in Yangon City, Myanmar. We determined high pyrethroid resistance in Aedes aegypti larvae at all collection sites in Yangon City, by using a simplified knockdown bioassay. We showed that V1016G and S989P mutations were widely distributed, with high frequencies (84.4% and 78.8%, respectively). By contrast, we were unable to detect I1011M (or I1011V) or L1014F mutations. F1534C mutations were also widely distributed, but with a lower frequency than the V1016G mutation (21.2%). High percentage of co-occurrence of the homozygous V1016G/S989P mutations was detected (65.7%). Additionally, co-occurrence of homozygous V1016G/F1534C mutations (2.9%) and homozygous V1016G/F1534C/S989P mutations (0.98%) were detected in the present study. Pyrethroid insecticides were first used for malaria control in 1992, and have since been constantly used in Myanmar. This intensive use may explain the strong selection pressure toward Aedes aegypti, because this mosquito is generally a domestic and endophagic species with a preference for indoor breeding. Extensive use of DDT for malaria control before the use of this chemical was banned may also explain the development of pyrethroid resistance in Aedes aegypti.

  12. Elite Indica transgenic rice plants expressing modified Cry1Ac endotoxin of Bacillus thuringiensis show enhanced resistance to yellow stem borer (Scirpophaga incertulas).

    Science.gov (United States)

    Khanna, H K; Raina, S K

    2002-08-01

    Bt-transgenics of elite indica rice breeding lines (IR-64, Pusa Basmati-1 and Karnal Local) were generated through biolistic or Agrobacterium-mediated approaches. A synthetic cry1Ac gene, codon optimised for rice and driven by the maize ubiquitin-1 promoter, was used. Over 200 putative transformants of IR-64 and Pusa Basmati-1 and 26 of the Karnal Local were regenerated following use of the hpt (hygromycin phosphotransferase) selection system. Initial transformation frequency was in the range of 1 to 2% for particle bombardment while it was comparatively higher (approximately 9%) for Agrobacterium. An improved selection procedure, involving longer selection on the antibiotic-supplemented medium, enhanced the frequency of Bt-transformants and reduced the number of escapes. Molecular evaluation revealed multiple transgene insertions in transformants, whether generated through biolistic or Agrobacterium. In the latter case, it was also observed that all genes on the T-DNA do not necessarily get transferred as an intact insert. Selected Bt-lines of IR-64 and Pusa Basmati-1, having Bt-titers of 0.1% (of total soluble protein) and above were evaluated for resistance against manual infestation of freshly hatched neonate larvae of yellow stem borers collected from a hot spot stem borer infested area in northern India. Several Bt-lines were identified showing 100% mortality of larvae, within 4-days of infestation, in cut-stem as well as vegetative stage whole plant assays. However, there was an occasional white head even among such plants when assayed at the reproductive stage. Results are discussed in the light of resistance management strategies for deployment of Bt-rice.

  13. 基于电压控制特性的电压源型多端直流/交流系统潮流求解%Power Flow Solving of VSC Multi-terminal DC/AC System Based on Voltage Control Characteristics

    Institute of Scientific and Technical Information of China (English)

    杨堤; 程浩忠; 姚良忠; 曾平良

    2016-01-01

    The voltage source converter based high voltage direct current (VSC-HVDC) transmission technology has good application prospects owing to its excellent controllability,voltage stability and good adaptability to power supply for load center,wind power accommodation,and power transmission among islands.The present research on power flow of VSC-HVDC system is mostly based on constant power control mode without considering the practical converter voltage control characteristics.In order to more accurately reflect the voltage control characteristics of VSC in the actual power grid,a voltage control model based on VSC is developed.As well,converter loss,AC filter,and converter capacity limit are considered in the power flow model.And a general power flow algorithm is proposed for power flow of the VSC based multi-terminal DC/AC system.Some cases with changed DC grid power injection,N -1 contingency and multi-terminal DC/AC system,are built and analyzed.The case analysis indicates that the power flow algorithm is able to reflect the voltage control ability of DC converters,while verifying the effectiveness,rationality and algorithm rapidity based on voltage control characteristics.%由于基于电压源型换流器的高压直流(VSC-HVDC)输电技术具有良好的可控性,对负荷中心供电、风电消纳、孤岛电力传输等适应能力强,电压稳定性好,因此具有良好的应用前景。当前对VSC-HVDC 系统主要基于定功率控制模式进行潮流计算,而很少考虑到实际的换流器电压控制能力。为了更加精确地反映实际电网中 VSC 的电压控制特性,文中建立了基于 VSC 的电压控制模型,考虑了换流器损耗、交流滤波器、换流器容量限制等的影响,并基于电压控制特性提出了 VSC多端直流/交流系统的通用潮流求解方法。对直流电网功率分布变化和 N -1故障以及多端直流/交流系统的潮流算例分析表明,所提的潮流算法能够反

  14. 1000 kV 交流特高压输电线路运行特性分析%Analysis of 1 000 kV AC Ultra High Voltage Power Transmission Line Operation Characteristics

    Institute of Scientific and Technical Information of China (English)

    曹旭佳

    2015-01-01

    1000 kV 交流特高压输电线路是解决我国电力能源分布不均匀,降低电力负荷的有效手段。1000 kV 交流特高压线路的维护工作也开始受到社会各界的广泛关注。为了保障交流特高压线路能够安全运行,文章分析了1000 kV 交流特高压输电线路运行特性,借鉴了国外先进经验,总结了其中的关键技术。%1 000 kV AC UHV transmission line is an effective means of uneven distribution of electric energy,reduce the power load solutions,the maintenance work of 1 000 kV AC UHV line has begun to attract widespread concern in the community,in order to protect AC UHV safe operation,we must summarize the key technologies,learn from foreign ad-vanced experience,this paper analyzes the operating characteristics of 1 000 kV UHV AC transmission lines.

  15. Analysis of temperature-dependant current–voltage characteristics and extraction of series resistance in Pd/ZnO Schottky barrier diodes

    Energy Technology Data Exchange (ETDEWEB)

    Mayimele, M A, E-mail: meehleketo@gmail.com; Rensburg, J P van. Janse; Auret, F D; Diale, M

    2016-01-01

    We report on the analysis of current voltage (I–V) measurements performed on Pd/ZnO Schottky barrier diodes (SBDs) in the 80–320 K temperature range. Assuming thermionic emission (TE) theory, the forward bias I–V characteristics were analysed to extract Pd/ZnO Schottky diode parameters. Comparing Cheung’s method in the extraction of the series resistance with Ohm’s law, it was observed that at lower temperatures (T<180 K) the series resistance decreased with increasing temperature, the absolute minimum was reached near 180 K and increases linearly with temperature at high temperatures (T>200 K). The barrier height and the ideality factor decreased and increased, respectively, with decrease in temperature, attributed to the existence of barrier height inhomogeneity. Such inhomogeneity was explained based on TE with the assumption of Gaussian distribution of barrier heights with a mean barrier height of 0.99 eV and a standard deviation of 0.02 eV. A mean barrier height of 0.11 eV and Richardson constant value of 37 A cm{sup −2} K{sup −2} were determined from the modified Richardson plot that considers the Gaussian distribution of barrier heights.

  16. Implementation and Control of an AC/DC/AC Converter for Double Wound Flywheel Application

    Directory of Open Access Journals (Sweden)

    J. G. Oliveira

    2012-01-01

    Full Text Available An all-electric driveline based on a double wound flywheel, connected in series between main energy storage and a wheel motor, is presented. The flywheel works as a power buffer, allowing the battery to deliver optimized power. It also separates electrically the system in two sides, with the battery connected to the low voltage side and the wheel motor connected to the high voltage side. This paper presents the implementation and control of the AC/DC/AC converter, used to connect the flywheel high voltage windings to the wheel motor. The converter general operation and the adopted control strategy are discussed. The implementation of the AC/DC/AC converter has been described from a practical perspective. Results from experimental tests performed in the full-system prototype are presented. The prototype system is running with satisfactory stability during acceleration mode. Good efficiency and unity power factor could be achieved, based on vector control and space vector modulation.

  17. Cathodic voltage-controlled electrical stimulation of titanium for prevention of methicillin-resistant Staphylococcus aureus and Acinetobacter baumannii biofilm infections.

    Science.gov (United States)

    Canty, Mary; Luke-Marshall, Nicole; Campagnari, Anthony; Ehrensberger, Mark

    2017-01-15

    Antibiotic resistance of bacterial biofilms limits available treatment methods for implant-associated orthopaedic infections. This study evaluated the effects of applying cathodic voltage-controlled electrical stimulations (CVCES) of -1.5V and -1.8V (vs. Ag/AgCl) to coupons of commercially pure titanium (cpTi) incubated in cultures of methicillin-resistant Staphylococcus aureus (MRSA) and Acinetobacter baumannii (A. baumannii) as a method of preventing bacterial attachment. Stimulations were applied for 2, 4, and 8h and coupon-associated and planktonic colony-forming units (CFU) were enumerated following stimulation. Compared to open circuit potential (OCP) controls, CVCES for 4h at -1.8V significantly reduced coupon-associated MRSA CFU by 99.9% (1.30×10(4)vs. 4.45×10(7), p=0.047) and A. baumannii coupon-associated CFU by 99.9% (1.64×10(4)vs. 5.93×10(7), p=0.001) and reduced planktonic CFU below detectable levels for both strains. CVCES at -1.8V for 8h also reduced coupon-associated and planktonic CFU below detectable levels for each strain. CVCES at -1.5V for 4 and 8h, and -1.8V for 2h did not result in clinically relevant reductions. For 4 and 8h stimulations, the current density was significantly higher for -1.8V than -1.5V, an effect directly related to the rate of water and oxygen reduction on the cpTi surface. This significantly increased the pH, a suspected influence in decreased CFU viability. The voltage-dependent electrochemical properties of cpTi likely contribute to the observed antimicrobial effects of CVCES. This study revealed that CVCES of titanium could prevent coupon-associated and planktonic CFU of Gram-positive MRSA and Gram-negative A. baumannii from reaching detectable levels in a magnitude-dependent and time-dependent manner.

  18. Development of a voltage scanner of chopper

    CERN Document Server

    Shen Guan Ren; LiShengLi; WangQuanXing; Wu Long Cheng

    2001-01-01

    Development of voltage sweeper of chopper with CPNG are introduced. Voltage sweeper is one of important key parts of chopper. Two years working prove that it is stable and reliable. Its main technology performance save: sine wave frequency: 750 kHz +- 20 Hz; total distortion: 65 Db; output voltage (V-V): 0->=4000 V; the error7 W; voltage supply: 220V AC +-10%, 50 +- 1 Hz; total power supply: <100W; Work temperature range: 0 - 40 degree; Stability in long time <=1%

  19. Effect of AC electric fields on the stabilization of premixed bunsen flames

    KAUST Repository

    Kim, Minkuk

    2011-01-01

    The stabilization characteristics of laminar premixed bunsen flames have been investigated experimentally for stoichiometric methane-air mixture by applying AC voltage to the nozzle with the single-electrode configuration. The detachment velocity either at blowoff or partial-detachment has been measured by varying the applied voltage and frequency of AC. The result showed that the detachment velocity increased with the applied AC electric fields, such that the flame could be nozzle-attached even over five times of the blowoff velocity without having electric fields. There existed four distinct regimes depending on applied AC voltage and frequency. In the low voltage regime, the threshold condition of AC electric fields was identified, below which the effect of electric fields on the detachment velocity is minimal. In the moderate voltage regime, the flame base oscillated with the frequency synchronized to AC frequency and the detachment velocity increased linearly with the applied AC voltage and nonlinearly with the frequency. In the high voltage regime, two different sub-regimes depending on AC frequency were observed. For relatively low frequency, the flame base oscillated with the applied AC frequency together with the half frequency and the variation of the detachment velocity was insensitive to the applied voltage. For relatively high frequency, the stabilization of the flame was significantly affected by the generation of streamers and the detachment velocity decreased with the applied voltage. © 2010 Published by Elsevier Inc. on behalf of The Combustion Institute. All rights reserved.

  20. Magnetic field cycling effect on the non-linear current-voltage characteristics and magnetic field induced negative differential resistance in α-Fe1.64Ga0.36O3 oxide

    Directory of Open Access Journals (Sweden)

    R. N. Bhowmik

    2015-06-01

    Full Text Available We have studied current-voltage (I-V characteristics of α-Fe1.64Ga0.36O3, a typical canted ferromagnetic semiconductor. The sample showed a transformation of the I-V curves from linear to non-linear character with the increase of bias voltage. The I-V curves showed irreversible features with hysteresis loop and bi-stable electronic states for up and down modes of voltage sweep. We report positive magnetoresistance and magnetic field induced negative differential resistance as the first time observed phenomena in metal doped hematite system. The magnitudes of critical voltage at which I-V curve showed peak and corresponding peak current are affected by magnetic field cycling. The shift of the peak voltage with magnetic field showed a step-wise jump between two discrete voltage levels with least gap (ΔVP 0.345(± 0.001 V. The magnetic spin dependent electronic charge transport in this new class of magnetic semiconductor opens a wide scope for tuning large electroresistance (∼500-700%, magnetoresistance (70-135 % and charge-spin dependent conductivity under suitable control of electric and magnetic fields. The electric and magnetic field controlled charge-spin transport is interesting for applications of the magnetic materials in spintronics, e.g., magnetic sensor, memory devices and digital switching.

  1. 隔离式SEPIC三电平AC-AC变换器的研究%Research of Isolated SEPIC Three-level AC - AC Converter

    Institute of Scientific and Technical Information of China (English)

    周振军; 李磊

    2011-01-01

    电力电子装置已在电力系统中得到了越来越广泛的应用,代表之一就是交流调压稳压装置.但是目前的交流调压稳压器多数采用AC-DC-AC的变换方式,这种调压稳压器不仅体积大、噪音大,而且开关管的电压应力大、输出电压波形质量低.提出了一种新型的隔离式交-交变换器,它是在sepic变换器(单端初级电感转换器)的基础上引入了推挽式变压器实现电气隔离.分析了工作原理,给出了控制策略,并通过仿真论证了变换器开关管电压应力小、输出电压波形质量高等特点.%Power electronics have been more widely used in power systems. One representative of power electronics is AC voltage regulator. But the AC - DC - AC conversion type is widely used for voltage regulator now. These AC voltage regulator not only have big bulk and high noise,but also with high power switch voltage stress and low quality of output waveform. To solve these problems)an isolated three-level AC - AC direct converter was proposed. It joined the push-pull transformer to achieve electrical isolation based on sepic AC -AC converter. Its operation principle and control strategies of the converter were investigated. By modeling and simulation,the performances of the AC - AC converter were verified, such as low switch voltage stress, high quality of output waveform and so on.

  2. Voltage modulation of propagating spin waves in Fe

    Energy Technology Data Exchange (ETDEWEB)

    Nawaoka, Kohei; Shiota, Yoichi; Miwa, Shinji; Tamura, Eiiti [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); CREST, Japan Science Technology, Kawaguchi, Saitama 332-0012 (Japan); Tomita, Hiroyuki; Mizuochi, Norikazu; Shinjo, Teruya [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Suzuki, Yoshishige, E-mail: suzuki-y@mp.es.osaka-u.ac.jp [Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531 (Japan); CREST, Japan Science Technology, Kawaguchi, Saitama 332-0012 (Japan); Display and Semiconductor Physics Department, Korea University, Sejong 339-700 (Korea, Republic of)

    2015-05-07

    The effect of a voltage application on propagating spin waves in single-crystalline 5 nm-Fe layer was investigated. Two micro-sized antennas were employed to excite and detect the propagating spin waves. The voltage effect was characterized using AC lock-in technique. As a result, the resonant field of the magnetostatic surface wave in the Fe was clearly modulated by the voltage application. The modulation is attributed to the voltage induced magnetic anisotropy change in ferromagnetic metals.

  3. DC-Modulated PFC Buck-Type AC/AC Converter for Light Dimming

    Institute of Scientific and Technical Information of China (English)

    罗方林; 叶虹

    2007-01-01

    Dimmers are very widely applied in theatres, cinemas, dancing-parties, auditoriums and signal systems. They are usually supplied by single-stage AC/AC converters in the past with voltage regulation technique with the disadvantages of high total harmonic distortion, low power factor and poor power transfer efficiency. This paper introduces a novel method-DC-modulation that implements DC/DC conversion technology into AC/AC converters. The DC-modulated single-stage PFC AC/AC converters effectively improved the power factor up to 0.999 and the power transfer efficiency up to 97.8 %. The experimental results verified our design and calculation. This technique will be widely used in light dimming and other industrial applications.

  4. Flexible AC transmission systems modelling and control

    CERN Document Server

    Zhang, Xiao-Ping; Pal, Bikash

    2012-01-01

    The extended and revised second edition of this successful monograph presents advanced modeling, analysis and control techniques of Flexible AC Transmission Systems (FACTS). The book covers comprehensively a range of power-system control problems: from steady-state voltage and power flow control, to voltage and reactive power control, to voltage stability control, to small signal stability control using FACTS controllers. In the six years since the first edition of the book has been published research on the FACTS has continued to flourish while renewable energy has developed into a mature and

  5. Marker-assisted selection on E. coli F4ab/ac resistance and the effect on neonatal survival in piglets

    DEFF Research Database (Denmark)

    Jørgensen, Claus Bøttcher; Anderson, Susan I.; Cirera, Susanna;

    Enterotoxigenic Escherichia coli (ETEC) that express the F4ab or F4ac fimbriae (formerly known as K88ab/ac) are major causes of diarrhea and death in neonatal and young pigs. A locus controlling susceptibility towards ETEC F4ab/ac has previously been mapped to pig chromosome 13q41. A number...... to the genomic sequence of pig mucin 4 we also report on more than 15 SNPs discovered in the porcine MUC4 sequence. Collaboration with the Danish Slaughterhouses on genotyping of the intron 7 SNP of Mucin 4 in 6.373 breeding boars (3.432 Landrace and 2.941 Large White) and analysis of their offspring has...... revealed data of relevance to neonatal survival. Analysis on offspring from 6.373 animals show a highly significant (P

  6. 单相重合时序对特高压交直流并联系统暂稳影响的机理分析%Mechanism Analysis of Single-Phase Reclosure Sequence's Influence on Ultra-High Voltage AC/DC Parallel System

    Institute of Scientific and Technical Information of China (English)

    孙士云; 束洪春; 于继来

    2009-01-01

    There is larger effect of single-phase reclosure sequence on ultra-high voltage AC/DC parallel system's transient stability. To discuss the inherent mechanism of this issue, single generator-ultra-high voltage AC/DC parallel transmission-infinite bus system is constructed, and equivalent AC impedance of DC system is derived based on switch function method and thus electromagnetic power expression is obtained. By analyzing the changing characteristic of power angle during the whole process that single-phase permanent fault is occurred, single-phase breaker is tripped, reclose to permanent fault and three phase breaker is tripped, influence of single-phase reclosure sequence on system's transient angle stability is described. Setting criterion of reclosure sequence to decrease acceleration area and enhance system's transient stability is proposed, i.e. to reclose on the terminal with smaller equivalent impedance of system. Correctness and effectiveness of the criterion is simulated in single generator-ultra-high voltage AC/DC parallel transmission-infinite bus system and south China power grid in 2010.%重合闸时序对特高压交直流并联系统暂态稳定性有较大的影响,为探讨其内在机理,构造了单机特高压交直流并联输电无穷大系统,采用开关函数法推导出直流系统的等值交流阻抗,得到了系统电磁功率的解析表达式.通过分析一回交流线路发生单相永久接地故障、故障相跳闸、故障相重合于永久故障、三相跳闸的整个过程中发电机的功角变化特性,利用等面积法则从机理上阐述了重合时序对系统功角稳定性的影响.提出了单相重合时序设置判据,即使系统等值阻抗较小的一侧首先重合,以期减小系统的加速面积,提高并联系统的暂态功角稳定性.在单机特高压交直流并联无穷大系统和2010年南方电网中,对该判据的正确性和有效性进行了仿真验证.

  7. Transport AC Losses in Striated YBCO Coated Conductors (Postprint)

    Science.gov (United States)

    2012-02-01

    AFRL-RZ-WP-TP-2012-0124 TRANSPORT AC LOSSES IN STRIATED YBCO COATED CONDUCTORS (POSTPRINT) G.A. Levin and P.N. Barnes Mechanical Energy...TRANSPORT AC LOSSES IN STRIATED YBCO COATED CONDUCTORS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT NUMBER 5c. PROGRAM ELEMENT...2006. 14. ABSTRACT DC current-voltage characteristics and transport ac losses of striated and non-striated Y1Ba2Cu3O7-δ ( YBCO ) coated conductors

  8. Method and system for a gas tube switch-based voltage source high voltage direct current transmission system

    Energy Technology Data Exchange (ETDEWEB)

    She, Xu; Chokhawala, Rahul Shantilal; Zhou, Rui; Zhang, Di; Sommerer, Timothy John; Bray, James William

    2016-12-13

    A voltage source converter based high-voltage direct-current (HVDC) transmission system includes a voltage source converter (VSC)-based power converter channel. The VSC-based power converter channel includes an AC-DC converter and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and a DC-AC inverter include at least one gas tube switching device coupled in electrical anti-parallel with a respective gas tube diode. The VSC-based power converter channel includes a commutating circuit communicatively coupled to one or more of the at least one gas tube switching devices. The commutating circuit is configured to "switch on" a respective one of the one or more gas tube switching devices during a first portion of an operational cycle and "switch off" the respective one of the one or more gas tube switching devices during a second portion of the operational cycle.

  9. Mitigation of Voltage Dip and Voltage Flickering by Multilevel D-STATCOM

    Directory of Open Access Journals (Sweden)

    M. S. Ballal

    2012-01-01

    Full Text Available The basic power quality problems in the distribution network are voltage sag (dip, voltage flickering, and the service interruptions. STATCOM is a Flexible AC Transmission Systems (FACTS technology device which can independently control the flow of reactive power. This paper presents the simulation and analysis of a STATCOM for voltage dip and voltage flickering mitigation. Simulations are carried out in MATLAB/Simulink to validate the performance of the STATCOM. A comparison between the six-pulse inverter and the five-level diode-clamped inverter is carried out for the performance of 66/11 KV distribution system.

  10. Safe-commutation principle for direct single-phase AC-AC converters for use in audio power amplification

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach...

  11. Safe-commutation principle for direct single-phase AC-AC converters for use in audio power amplification

    DEFF Research Database (Denmark)

    Ljusev, Petar; Andersen, Michael Andreas E.

    2004-01-01

    This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach...

  12. 电缆绝缘电阻测试仪中高压电源的设计*%Design of High-Voltage Power Supply of Cable Insulation Resistance Tester

    Institute of Scientific and Technical Information of China (English)

    李琳琳; 王二宝; 孙继银; 恒波; 肖明芳

    2013-01-01

      To meet the power requirements of inputting low voltage and outputting high-voltage during cable insulation resistance test, the paper proposes a new type of active clamp voltage multiplying converters by analyzing and improving the technical of analysis active clamp pulse width modulation and voltage double rectifier. It uses main circuit in active clamp technique to achieve magnetic core flux automatic reset and increases core utilization. The clamp capacitor with other components produces resonant achieving opened switch to zero pressure, which reduces the switching loss and voltage stress. Doubling voltage technique is used to reduce transformer step-up requirements and converter bulk. Taking advantage of negative feedback in control loop,input output voltage into PWM chip and control pulse duty cycle can increase power stability and load characteristics. The software simulation result shows that the converter is able to provide a stable high insulation resistance test voltage.%  为满足电缆绝缘电阻测试“低电压输入,高电压输出”的需求,对有源钳位、脉宽调制和倍压整流等技术分析改进,提出一种新型的有源钳位倍压变换器。主回路中利用有源钳位技术实现磁芯磁通自动复位,提高了磁芯利用率,钳位电容与元器件产生谐振实现开关零压开通,减小开关损耗和电压应力;利用倍压技术降低变压器升压要求,减小了变换器体积;在控制回路中利用负反馈将输出电压输入脉宽调制芯片,控制脉冲占空比,提高了电源稳定性和负载特性。用软件仿真结果表明,该变换器能够为绝缘电阻测试提供稳定的高电压。

  13. Impulse voltage control of continuously tunable bipolar resistive switching in Pt/Bi0.9Eu0.1FeO3/Nb-doped SrTiO3 heterostructures

    Science.gov (United States)

    Wei, Maocai; Liu, Meifeng; Wang, Xiuzhang; Li, Meiya; Zhu, Yongdan; Zhao, Meng; Zhang, Feng; Xie, Shuai; Hu, Zhongqiang; Liu, Jun-Ming

    2017-03-01

    Epitaxial Bi0.9Eu0.1FeO3 (BEFO) thin films are deposited on Nb-doped SrTiO3 (NSTO) substrates by pulsed laser deposition to fabricate the Pt/BEFO/NSTO (001) heterostructures. These heterostructures possess bipolar resistive switching, where the resistances versus writing voltage exhibits a distinct hysteresis loop and a memristive behavior with good retention and anti-fatigue characteristics. The local resistive switching is confirmed by the conductive atomic force microscopy (C-AFM), suggesting the possibility to scale down the memory cell size. The observed memristive behavior could be attributed to the ferroelectric polarization effect, which modulates the height of potential barrier and width of depletion region at the BEFO/NSTO interface. The continuously tunable resistive switching behavior could be useful to achieve non-volatile, high-density, multilevel random access memory with low energy consumption.

  14. Impulse voltage control of continuously tunable bipolar resistive switching in Pt/Bi{sub 0.9}Eu{sub 0.1}FeO{sub 3}/Nb-doped SrTiO{sub 3} heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Maocai; Liu, Meifeng; Wang, Xiuzhang [Hubei Normal University, Institute for Advanced Materials, and School of Physics and Electronic Science, Huangshi (China); Li, Meiya; Zhu, Yongdan; Zhao, Meng; Zhang, Feng; Xie, Shuai [Wuhan University, School of Physics and Technology, and Key Laboratory of Artificial Micro/Nano Structures of the Ministry of Education, Wuhan (China); Hu, Zhongqiang [Northeastern University, Department of Electrical and Computer Engineering, Boston, MA (United States); Liu, Jun-Ming [Nanjing University, Laboratory of Solid State Microstructures, Nanjing (China)

    2017-03-15

    Epitaxial Bi{sub 0.9}Eu{sub 0.1}FeO{sub 3} (BEFO) thin films are deposited on Nb-doped SrTiO{sub 3} (NSTO) substrates by pulsed laser deposition to fabricate the Pt/BEFO/NSTO (001) heterostructures. These heterostructures possess bipolar resistive switching, where the resistances versus writing voltage exhibits a distinct hysteresis loop and a memristive behavior with good retention and anti-fatigue characteristics. The local resistive switching is confirmed by the conductive atomic force microscopy (C-AFM), suggesting the possibility to scale down the memory cell size. The observed memristive behavior could be attributed to the ferroelectric polarization effect, which modulates the height of potential barrier and width of depletion region at the BEFO/NSTO interface. The continuously tunable resistive switching behavior could be useful to achieve non-volatile, high-density, multilevel random access memory with low energy consumption. (orig.)

  15. Determination of appropriate DC voltage for switched mode power supply (SMPS) loads

    Science.gov (United States)

    Setiawan, Eko Adhi; Setiawan, Aiman; Purnomo, Andri; Djamal, Muchlishah Hadi

    2017-03-01

    Nowadays, most of modern and efficient household electronic devices operated based on Switched Mode Power Supply (SMPS) technology which convert AC voltage from the grid to DC voltage. Based on theory and experiment, SMPS loads could be supplied by DC voltage. However, the DC voltage rating to energize electronic home appliances is not standardized yet. This paper proposed certain method to determine appropriate DC voltage, and investigated comparison of SMPS power consumption which is supplied from AC and DC voltage. To determine the appropriate DC voltage, lux value of several lamps which have same specification energized by using AC voltage and the results is using as reference. Then, the lamps were supplied by various DC voltage to obtain the trends of the lux value to the applied DC voltage. After that, by using the trends and the reference lux value, the appropriate DC voltage can be determined. Furthermore, the power consumption on home appliances such as mobile phone, laptop and personal computer by using AC voltage and the appropriate DC voltage were conducted. The results show that the total power consumption of AC system is higher than DC system. The total power (apparent power) consumed by the lamp, mobile phone and personal computer which operated in 220 VAC were 6.93 VA, 34.31 VA and 105.85 VA respectively. On the other hand, under 277 VDC the load consumption were 5.83 W, 19.11 W and 74.46 W respectively.

  16. AC 410 AC410 AC410 Unit 7 Homework Assignment

    OpenAIRE

    Laynebaril1

    2017-01-01

    AC 410 AC410 AC410 Unit 7 Homework Assignment Click Link Below To Buy: http://hwcampus.com/shop/ac410-unit-7-homework-assignment/    Questions Requiring Analysis 14-30   Early in your first audit of Star Corporation, you notice that sales and year-end inventory are almost unchanged from the prior year. However, cost of goods sold is less than in the preceding year, and accounts payable also are down substantially. Gross profit has increased, but this increase has not c...

  17. Recovery of consciousness in broilers following combined dc and ac stunning

    Science.gov (United States)

    Broilers in the United States are typically electrically stunned using low voltage-high frequency pulsed DC water bath stunners and in the European Union broilers are electrocuted using high voltage-low frequency AC. DC stunned broilers regain consciousness in the absence of exsanguination and AC st...

  18. Cry1Ac and Vip3Aa proteins from Bacillus thuringiensis targeting Cry toxin resistance in Diatraea flavipennella and Elasmopalpus lignosellus from sugarcane.

    Science.gov (United States)

    Lemes, Ana Rita Nunes; Figueiredo, Camila Soares; Sebastião, Isis; Marques da Silva, Liliane; da Costa Alves, Rebeka; de Siqueira, Herbert Álvaro Abreu; Lemos, Manoel Victor Franco; Fernandes, Odair Aparecido; Desidério, Janete Apparecida

    2017-01-01

    The biological potential of Vip and Cry proteins from Bacillus is well known and widely established. Thus, it is important to look for new genes showing different modes of action, selecting those with differentiated entomotoxic activity against Diatraea flavipennella and Elasmopalpus lignosellus, which are secondary pests of sugarcane. Therefore, Cry1 and Vip3 proteins were expressed in Escherichia coli, and their toxicities were evaluated based on bioassays using neonate larvae. Of those, the most toxic were Cry1Ac and Vip3Aa considering the LC50 values. Toxins from E. coli were purified, solubilized, trypsinized, and biotinylated. Brush Border Membrane Vesicles (BBMVs) were prepared from intestines of the two species to perform homologous and heterologous competition assays. The binding assays demonstrated interactions between Cry1Aa, Cry1Ac, and Vip3Aa toxins and proteins from the BBMV of D. flavipennella and E. lignosellus. Homologous competition assays demonstrated that binding to one of the BBMV proteins was specific for each toxin. Heterologous competition assays indicated that Vip3Aa was unable to compete for Cry1Ac toxin binding. Our results suggest that Cry1Ac and Vip3Aa may have potential in future production of transgenic sugarcane for control of D. flavipennella and E. lignosellus, but more research is needed on the potential antagonism or synergism of the toxins in these pests.

  19. Cry1Ac and Vip3Aa proteins from Bacillus thuringiensis targeting Cry toxin resistance in Diatraea flavipennella and Elasmopalpus lignosellus from sugarcane

    Science.gov (United States)

    2017-01-01

    The biological potential of Vip and Cry proteins from Bacillus is well known and widely established. Thus, it is important to look for new genes showing different modes of action, selecting those with differentiated entomotoxic activity against Diatraea flavipennella and Elasmopalpus lignosellus, which are secondary pests of sugarcane. Therefore, Cry1 and Vip3 proteins were expressed in Escherichia coli, and their toxicities were evaluated based on bioassays using neonate larvae. Of those, the most toxic were Cry1Ac and Vip3Aa considering the LC50 values. Toxins from E. coli were purified, solubilized, trypsinized, and biotinylated. Brush Border Membrane Vesicles (BBMVs) were prepared from intestines of the two species to perform homologous and heterologous competition assays. The binding assays demonstrated interactions between Cry1Aa, Cry1Ac, and Vip3Aa toxins and proteins from the BBMV of D. flavipennella and E. lignosellus. Homologous competition assays demonstrated that binding to one of the BBMV proteins was specific for each toxin. Heterologous competition assays indicated that Vip3Aa was unable to compete for Cry1Ac toxin binding. Our results suggest that Cry1Ac and Vip3Aa may have potential in future production of transgenic sugarcane for control of D. flavipennella and E. lignosellus, but more research is needed on the potential antagonism or synergism of the toxins in these pests. PMID:28123906

  20. Cry1Ac and Vip3Aa proteins from Bacillus thuringiensis targeting Cry toxin resistance in Diatraea flavipennella and Elasmopalpus lignosellus from sugarcane

    Directory of Open Access Journals (Sweden)

    Ana Rita Nunes Lemes

    2017-01-01

    Full Text Available The biological potential of Vip and Cry proteins from Bacillus is well known and widely established. Thus, it is important to look for new genes showing different modes of action, selecting those with differentiated entomotoxic activity against Diatraea flavipennella and Elasmopalpus lignosellus, which are secondary pests of sugarcane. Therefore, Cry1 and Vip3 proteins were expressed in Escherichia coli, and their toxicities were evaluated based on bioassays using neonate larvae. Of those, the most toxic were Cry1Ac and Vip3Aa considering the LC50 values. Toxins from E. coli were purified, solubilized, trypsinized, and biotinylated. Brush Border Membrane Vesicles (BBMVs were prepared from intestines of the two species to perform homologous and heterologous competition assays. The binding assays demonstrated interactions between Cry1Aa, Cry1Ac, and Vip3Aa toxins and proteins from the BBMV of D. flavipennella and E. lignosellus. Homologous competition assays demonstrated that binding to one of the BBMV proteins was specific for each toxin. Heterologous competition assays indicated that Vip3Aa was unable to compete for Cry1Ac toxin binding. Our results suggest that Cry1Ac and Vip3Aa may have potential in future production of transgenic sugarcane for control of D. flavipennella and E. lignosellus, but more research is needed on the potential antagonism or synergism of the toxins in these pests.

  1. A simple technique for a.c. conductivity measurements

    Indian Academy of Sciences (India)

    R Padma Suvarna; K Raghavendra Rao; K Subbarangaiah

    2002-12-01

    An inexpensive, indigenous and a simple electronic instrument based on voltage follower, current–to–voltage converter, zero crossing detector and a phase detector has been developed for measurement of a.c. conductivity. Real and imaginary parts of complex impedance are determined for a given sample as a function of frequency and the given sample is represented by a pure electronic model.

  2. Analysis of Input and Output Ripples of PWM AC Choppers

    Directory of Open Access Journals (Sweden)

    Pekik Argo Dahono

    2008-11-01

    Full Text Available This paper presents an analysis of input and output ripples of PWM AC choppers. Expressions of input and output current and voltage ripples of single-phase PWM AC choppers are first derived. The derived expressions are then extended to three-phase PWM AC choppers. As input current and output voltage ripples specification alone cannot be used to determine the unique values of inductance and capacitance of the LC filters, an additional criterion based on the minimum reactive power is proposed. Experimental results are included in this paper to show the validity of the proposed analysis method.

  3. DC-link Voltage Control to Compensate Voltage Deviation for PV–BESSs Integrated System in Low-Voltage (LV Networks

    Directory of Open Access Journals (Sweden)

    Lee Gyu-sub

    2016-01-01

    Full Text Available The exhaustion of fossil fuel and the greenhouse gas emission are one of the most significant energy and environmental issues, respectively. Photovoltaic (PV generators and battery energy storage systems (BESSs have been significantly increased for recent years. The BESSs are mainly used for smoothing active power fluctuation of the PV. In this paper, PV–BESSs integration of two DC/DC converters and one AC/DC converter is investigated and DC-link voltage control to compensate the AC voltage deviation is proposed for the PV‒BESS system in low-voltage (LV networks.

  4. 30 CFR 75.804 - Underground high-voltage cables.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Underground high-voltage cables. 75.804 Section... AND HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Underground High-Voltage Distribution § 75.804 Underground high-voltage cables. (a) Underground high-voltage cables used in resistance...

  5. 交流传动机车与直流传动机车混合运用条件下牵引网电压控制技术%Traction Network Voltage Control Techniques under the Condition of Hybrid Application of AC Drive and DC Drive Locomotives

    Institute of Scientific and Technical Information of China (English)

    李强; 吴命利

    2014-01-01

    在大秦重载铁路上,担当万吨和两万吨重载列车牵引任务的即有 HXD1型、HXD2型交流传动电力机车,也有S S4型直流传动电力机车。由于这两种电力机车具有不同的电气负荷特性,在大秦线的部分区段,保持牵引变电所母线电压处在适当水平成为一个需要解决的技术问题。结合算例,本文给出因S S4型电力机车功率因数低而导致的网压降低和 HXD1型电力机车再生制动引起的网压升高的仿真计算结果,分析电源短路容量、牵引变压器、无功补偿装置以及牵引网阻抗对网压变动的影响。对包括使用有载调压牵引变压器、有载调压自耦变压器、晶闸管控制串联变压器、串联电容器和功率平衡调节器等在内的不同改善网压技术方案进行比较。基于现代电力电子技术的功率平衡调节器不但能有效稳定网压还能综合治理电能质量,有望为该问题提供最佳解决方案。%Both the AC drive locomotives , HXD1 and HXD2 , and the DC drive locomotive , SS4 , are designated for 10 000 t and 20 000 t heavy-duty haul on the Datong-Qinhuangdao Heavy-haul Railway Line . Due to the distinct electric loading characteristics of these two types of locomotives , how to maintain the bus bar voltage in traction substations in some sections of the Line at an appropriate level has become a technical issue to be handled .By a numerical example , the voltage drop caused by the low power factor of Locomotive SS4 and the voltage rise caused by the regenerative braking of Locomotive HXD1 were computed . The influences of the power source capacity , the traction transformer , the reactive power compensator and the impedance of the traction network on the voltage variations were analyzed . Different voltage improving schemes , including those schemes with use of the on-load tap changing traction transformer , the on-load voltage regulating auto-transformer , the thyristor

  6. A battery-based, low-noise voltage source

    Science.gov (United States)

    Wagner, Anke; Sturm, Sven; Schabinger, Birgit; Blaum, Klaus; Quint, Wolfgang

    2010-06-01

    A highly stable, low-noise voltage source was designed to improve the stability of the electrode bias voltages of a Penning trap. To avoid excess noise and ground loops, the voltage source is completely independent of the public electric network and uses a 12 V car battery to generate output voltages of ±15 and ±5 V. First, the dc supply voltage is converted into ac-voltage and gets amplified. Afterwards, the signal is rectified, filtered, and regulated to the desired output value. Each channel can deliver up to 1.5 A. The current as well as the battery voltage and the output voltages can be read out via a universal serial bus (USB) connection for monitoring purposes. With the presented design, a relative voltage stability of 7×10-7 over 6.5 h and a noise level equal or smaller than 30 nV/√Hz is achieved.

  7. Accurate Switched-Voltage voltage averaging circuit

    OpenAIRE

    金光, 一幸; 松本, 寛樹

    2006-01-01

    Abstract ###This paper proposes an accurate Switched-Voltage (SV) voltage averaging circuit. It is presented ###to compensated for NMOS missmatch error at MOS differential type voltage averaging circuit. ###The proposed circuit consists of a voltage averaging and a SV sample/hold (S/H) circuit. It can ###operate using nonoverlapping three phase clocks. Performance of this circuit is verified by PSpice ###simulations.

  8. Finding the lost open-circuit voltage in polymer solar cells by UV-ozone treatment of the nickel acetate anode buffer layer.

    Science.gov (United States)

    Wang, Fuzhi; Sun, Gang; Li, Cong; Liu, Jiyan; Hu, Siqian; Zheng, Hua; Tan, Zhan'ao; Li, Yongfang

    2014-06-25

    Efficient polymer solar cells (PSCs) with enhanced open-circuit voltage (Voc) are fabricated by introducing solution-processed and UV-ozone (UVO)-treated nickel acetate (O-NiAc) as an anode buffer layer. According to X-ray photoelectron spectroscopy data, NiAc partially decomposed to NiOOH during the UVO treatment. NiOOH is a dipole species, which leads to an increase in the work function (as confirmed by ultraviolet photoemission spectroscopy), thus benefitting the formation of ohmic contact between the anode and photoactive layer and leading to increased Voc. In addition, the UVO treatment improves the wettability between the substrate and solvent of the active layer, which facilitates the formation of an upper photoactive layer with better morphology. Further, the O-NiAc layer can decrease the series resistance (Rs) and increase the parallel resistance (Rp) of the devices, inducing enhanced Voc in comparison with the as-prepared NiAc-buffered control devices without UVO treatment. For PSCs based on the P3HT:PCBM system, Voc increases from 0.50 to 0.60 V after the NiAc buffer layer undergoes UVO treatment. Similarly, in the P3HT:ICBA system, the Voc value of the device with a UVO-treated NiAc buffer layer increases from 0.78 to 0.88 V, showing an enhanced power conversion efficiency of 6.64%.

  9. A Dual-Buck–Boost AC/DC Converter for DC Nanogrid With Three Terminal Outputs

    DEFF Research Database (Denmark)

    Wu, Weimin; Wang, Houqing; Liu, Yuan

    2017-01-01

    such as the low-voltage ac power system. There are three typical grounding configurations for a dc nanogrid: the united grounding, the unidirectional grounding, and the virtual isolated grounding. Each grounding configuration has its own specifications to ac/dc converters. In this paper, a dual-buck-boost ac...

  10. A single-phase embedded Z-source DC-AC inverter.

    Science.gov (United States)

    Kim, Se-Jin; Lim, Young-Cheol

    2014-01-01

    In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.

  11. Insulation measurement and supervision in live AC and DC unearthed systems

    CERN Document Server

    Olszowiec, Piotr

    2013-01-01

    Low voltage unearthed (IT) AC and DC systems are commonly applied for supply of power and control circuits in industry, transportation, medical objects etc. The main reasons for their use are high reliability and numerous advantages offered by isolating them against ground. Insulation level is a decisive factor for networks operational reliability and safety. Insufficient insulation-to-ground resistance can cause various disturbances. Though ground faults in IT systems do not make networks operation impossible, they may cause severe problems with their safe functioning. In this book the most important issues concerning normal operation and ground fault phenomena are described in concise form. Numerous methods of insulation resistance and capacitance measurement in live circuits are presented. Important other procedures of  these parameters determination based on measurement and calculation are explained and reviews of selected insulation resistance measurement devices as well as earth fault locating systems ...

  12. Insulation measurement and supervision in live AC and DC unearthed systems

    CERN Document Server

    Olszowiec, Piotr

    2014-01-01

    Low voltage unearthed (IT) AC and DC systems are commonly applied for supply of power and control circuits in industry, transportation, medical objects etc. The main reasons for their use are high reliability and numerous advantages offered by isolating them against ground. Insulation level is a decisive factor for networks operational reliability and safety. Insufficient insulation-to-ground resistance can cause various disturbances. Though ground faults in IT systems do not make networks operation impossible, they may cause severe problems with their safe functioning. In this book the most important issues concerning normal operation and ground fault phenomena are described in concise form. Numerous methods of insulation resistance and capacitance measurement in live circuits are presented. Important other procedures of  these parameters determination based on measurement and calculation are explained and reviews of selected insulation resistance measurement devices as well as earth fault locating systems ...

  13. Non-contact current and voltage sensor

    Science.gov (United States)

    Carpenter, Gary D; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C; Schappert, Michael A

    2014-03-25

    A detachable current and voltage sensor provides an isolated and convenient device to measure current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing that contains the current and voltage sensors, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, or alternative a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  14. A dry-cooled AC quantum voltmeter

    Science.gov (United States)

    Schubert, M.; Starkloff, M.; Peiselt, K.; Anders, S.; Knipper, R.; Lee, J.; Behr, R.; Palafox, L.; Böck, A. C.; Schaidhammer, L.; Fleischmann, P. M.; Meyer, H.-G.

    2016-10-01

    The paper describes a dry-cooled AC quantum voltmeter system operated up to kilohertz frequencies and 7 V rms. A 10 V programmable Josephson voltage standard (PJVS) array was installed on a pulse tube cooler (PTC) driven with a 4 kW air-cooled compressor. The operating margins at 70 GHz frequencies were investigated in detail and found to exceed 1 mA Shapiro step width. A key factor for the successful chip operation was the low on-chip power consumption of 65 mW in total. A thermal interface between PJVS chip and PTC cold stage was used to avoid a significant chip overheating. By installing the cryocooled PJVS array into an AC quantum voltmeter setup, several calibration measurements of dc standards and calibrator ac voltages up to 2 kHz frequencies were carried out to demonstrate the full functionality. The results are discussed and compared to systems with standard liquid helium cooling. For dc voltages, a direct comparison measurement between the dry-cooled AC quantum voltmeter and a liquid-helium based 10 V PJVS shows an agreement better than 1 part in 1010.

  15. Methods, systems and apparatus for controlling operation of two alternating current (AC) machines

    Science.gov (United States)

    Gallegos-Lopez, Gabriel; Nagashima, James M.; Perisic, Milun; Hiti, Silva

    2012-02-14

    A system is provided for controlling two AC machines. The system comprises a DC input voltage source that provides a DC input voltage, a voltage boost command control module (VBCCM), a five-phase PWM inverter module coupled to the two AC machines, and a boost converter coupled to the inverter module and the DC input voltage source. The boost converter is designed to supply a new DC input voltage to the inverter module having a value that is greater than or equal to a value of the DC input voltage. The VBCCM generates a boost command signal (BCS) based on modulation indexes from the two AC machines. The BCS controls the boost converter such that the boost converter generates the new DC input voltage in response to the BCS. When the two AC machines require additional voltage that exceeds the DC input voltage required to meet a combined target mechanical power required by the two AC machines, the BCS controls the boost converter to drive the new DC input voltage generated by the boost converter to a value greater than the DC input voltage.

  16. Common-mode Voltage Reduction in a Motor Drive System with a Power Factor Correction

    DEFF Research Database (Denmark)

    Adabi, J.; Boora, A.A.; Zare, F.;

    2012-01-01

    to reduce shaft voltage in a three-phase AC motor drive system. In this topology, the AC-DC diode rectifier influences the common-mode voltage generated by the inverter because the placement of the neutral point is changing in different rectifier circuit states. A pulse width modulation technique......Common-mode voltage generated by a power converter in combination with parasitic capacitive couplings is a potential source of shaft voltage in an AC motor drive system. In this study, a three-phase motor drive system supplied with a single-phase AC-DC diode rectifier is investigated in order...... is presented by a proper placement of the zero vectors to reduce the common-mode voltage level, which leads to a cost-effective shaft voltage reduction technique without load current distortion, while keeping the switching frequency constant. Analysis, simulations and experimental implementation have been...

  17. A Non-linear Controller for Single-Phase AC-AC Power Converter to meet UPS Performance Index

    Directory of Open Access Journals (Sweden)

    Abdelhafid Ait Elmahjoub

    2012-07-01

    Full Text Available This article focuses on AC-AC power converter that can be used for uninterruptible power supply (UPS. The converter is built on two stages: a AC-DC input stage and a DC-AC output stage. The two blocks are connected by an intermediate DC bus. The aim of control is threefold: i power factor correction ii regulation of DC bus iii generating a sinusoidal voltage at the output. The synthesis of controllers has been achieved through the technique of nonlinear backstepping control. A detailed analysis of the stability control system is presented. The performances of regulators have been validated by numerical simulation in MATLAB / SIMULINK.

  18. A Multi-Functional Fully Distributed Control Framework for AC Microgrids

    DEFF Research Database (Denmark)

    Shafiee, Qobad; Nasirian, Vahidreza; Quintero, Juan Carlos Vasquez

    2017-01-01

    This paper proposes a fully distributed control methodology for secondary control of AC microgrids. The control framework includes three modules: voltage regulator, reactive power regulator, and active power/frequency regulator. The voltage regulator module maintains the average voltage of the mi...

  19. Three-Level AC-DC-AC Z-Source Converter Using Reduced Passive Component Count

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Gao, Feng; Tan, Pee-Chin;

    2007-01-01

    This paper presents a three-level ac-dc-ac Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled...... to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can accurately produce...... the correct volt-sec average at its output, while simultaneously achieving inductive voltage boosting. More interestingly, these performance features are achieved with no increase in the number of semiconductor commutations, and hence no increase in switching losses. The proposed converter therefore offers...

  20. Development of a Triple Gene Cry1Ac-Cry2Ab-EPSPS Construct and Its Expression in Nicotiana benthamiana for Insect Resistance and Herbicide Tolerance in Plants

    Science.gov (United States)

    Naqvi, Rubab Z.; Asif, Muhammad; Saeed, Muhammad; Asad, Shaheen; Khatoon, Asia; Amin, Imran; Mukhtar, Zahid; Bashir, Aftab; Mansoor, Shahid

    2017-01-01

    Insect pest complex, cotton leaf curl disease and weeds pose major threat to crop production worldwide, including Pakistan. To address these problems, in the present study a triple gene construct harboring Cry1Ac, Cry2Ab, and EPSPS cassettes has been developed for plant specifically in cotton transformation against lepidopteron insect-pests and weeds. Nicotiana benthamiana (tobacco) was used as a model system for characterization of this triple gene construct. The construct has been assembled in plant expression vector and transformed in N. benthamiana. In six transgenic tobacco lines the integration of Cry1Ac-Cry2Ab-EPSPS in tobacco genome was checked by PCR, while successful protein expression of all the three genes was confirmed through immunostrip assay. Efficacy of Cry1Ac and Cry2Ab was evaluated through insect bioassay using armyworm (Spodoptera littoralis). These transgenic tobacco plants showed significant insect mortality as compared to control plants during insect bioassay. Three out of six tested transgenic lines L3, L5, and L9 exhibited 100% mortality of armyworm, while three other lines L1, L10, and L7 showed 86, 80, and 40% mortality, respectively. This construct can readily be used with confidence to transform cotton and other crops for the development of insect resistant and herbicide tolerant transgenic plants. The transgenic crop plants developed using this triple gene construct will provide an excellent germplasm resource for the breeders to improve their efficiency in developing stable homozygous lines as all the three genes being in a single T-DNA border will inherit together. PMID:28174591

  1. Development of a Triple Gene Cry1Ac-Cry2Ab-EPSPS Construct and Its Expression in Nicotiana benthamiana for Insect Resistance and Herbicide Tolerance in Plants.

    Science.gov (United States)

    Naqvi, Rubab Z; Asif, Muhammad; Saeed, Muhammad; Asad, Shaheen; Khatoon, Asia; Amin, Imran; Mukhtar, Zahid; Bashir, Aftab; Mansoor, Shahid

    2017-01-01

    Insect pest complex, cotton leaf curl disease and weeds pose major threat to crop production worldwide, including Pakistan. To address these problems, in the present study a triple gene construct harboring Cry1Ac, Cry2Ab, and EPSPS cassettes has been developed for plant specifically in cotton transformation against lepidopteron insect-pests and weeds. Nicotiana benthamiana (tobacco) was used as a model system for characterization of this triple gene construct. The construct has been assembled in plant expression vector and transformed in N. benthamiana. In six transgenic tobacco lines the integration of Cry1Ac-Cry2Ab-EPSPS in tobacco genome was checked by PCR, while successful protein expression of all the three genes was confirmed through immunostrip assay. Efficacy of Cry1Ac and Cry2Ab was evaluated through insect bioassay using armyworm (Spodoptera littoralis). These transgenic tobacco plants showed significant insect mortality as compared to control plants during insect bioassay. Three out of six tested transgenic lines L3, L5, and L9 exhibited 100% mortality of armyworm, while three other lines L1, L10, and L7 showed 86, 80, and 40% mortality, respectively. This construct can readily be used with confidence to transform cotton and other crops for the development of insect resistant and herbicide tolerant transgenic plants. The transgenic crop plants developed using this triple gene construct will provide an excellent germplasm resource for the breeders to improve their efficiency in developing stable homozygous lines as all the three genes being in a single T-DNA border will inherit together.

  2. Programmable high voltage power supply with regulation confined to the high voltage section

    Science.gov (United States)

    Castell, Karen D. (Inventor); Ruitberg, Arthur P. (Inventor)

    1994-01-01

    A high voltage power supply in a dc-dc converter configuration includes a pre-regulator which filters and regulates the dc input and drives an oscillator which applies, in turn, a low voltage ac signal to the low side of a step-up high voltage transformer. The high voltage side of the transformer drives a voltage multiplier which provides a stepped up dc voltage to an output filter. The output voltage is sensed by a feedback network which then controls a regulator. Both the input and output of the regulator are on the high voltage side, avoiding isolation problems. The regulator furnishes a portion of the drive to the voltage multiplier, avoiding having a regulator in series with the load with its attendant, relatively high power losses. This power supply is highly regulated, has low power consumption, a low parts count and may be manufactured at low cost. The power supply has a programmability feature that allows for the selection of a large range of output voltages.

  3. Transformerless DC-DC Converter Using Cockcroft-Walton Voltage Multiplier to Obtain High DC Voltage

    Directory of Open Access Journals (Sweden)

    Meghana G Naik,

    2014-11-01

    Full Text Available In the present scenario the use of transformer for high voltages in converter circuit reduces the overall operating efficiency due to leakage inductance and use of transformer also increases the operational cost. . Therefore the proposed system is implemented with transformer less DC-DC converter so as to obtain high DC voltage with the use of nine stage Cockcroft-Walton (CW voltage multiplier. The proposed converter operates in CCM (continuous conduction mode, so that the converter switch stress, the switching losses are reduced. The DC voltage at the input of the proposed model is low and is boosted up by boost inductor (Ls in DC-DC converter stage and performs inverter operation. The number of stages in CW-voltage multiplier circuit is applied with low input pulsating DC (AC Voltage voltage where it is getting converted to high DC output voltage. The proposed converter switches operates at two independent frequencies, modulating (fsm andalternating (fsc frequency. The fsm operates at higher frequency of the output while the fsc operates at lower frequency of the desired output voltage ripple and the output ripples can be adjusted by the switch Sc1 and Sc2. The regulation of the output voltage is achieved by controlling the Duty ratio.The simulation is carried over by the MATLABSIMULINK.

  4. Peltier ac calorimeter

    OpenAIRE

    Jung, D. H.; Moon, I. K.; Jeong, Y. H.

    2001-01-01

    A new ac calorimeter, utilizing the Peltier effect of a thermocouple junction as an ac power source, is described. This Peltier ac calorimeter allows to measure the absolute value of heat capacity of small solid samples with sub-milligrams of mass. The calorimeter can also be used as a dynamic one with a dynamic range of several decades at low frequencies.

  5. Influence of DSP controller on performance of a permanent magnet brushless AC drive in flux-weakening mode

    Institute of Scientific and Technical Information of China (English)

    ZHU Z.Q.; SHI Y.F.; HOWE D.

    2005-01-01

    The flux-weakening performance of a permanent magnet brushless AC drive was investigated using both floating-point and fixed-point DSP controllers. A significant current oscillation was observed when the drive was operated at high-speed in the flux-weakening mode with the fixed-point DSP. The investigation showed that this was due to the on-line compensation of the winding resistance voltage drop and quantisation errors associated with the fixed-point architecture of the DSP. A simple look-up table scheme is proposed to eliminate the oscillation and to achieve extended flux-weakening capability.

  6. 0.6-1.0 V operation set/reset voltage (3 V) generator for three-dimensional integrated resistive random access memory and NAND flash hybrid solid-state drive

    Science.gov (United States)

    Tanaka, Masahiro; Hachiya, Shogo; Ishii, Tomoya; Ning, Sheyang; Tsurumi, Kota; Takeuchi, Ken

    2016-04-01

    A 0.6-1.0 V, 25.9 mm2 boost converter is proposed to generate resistive random access memory (ReRAM) write (set/reset) voltage for three-dimensional (3D) integrated ReRAM and NAND flash hybrid solid-state drive (SSD). The proposed boost converter uses an integrated area-efficient V BUF generation circuit to obtain short ReRAM sector write time, small circuit size, and small energy consumption simultaneously. In specific, the proposed boost converter reduces ReRAM sector write time by 65% compared with a conventional one-stage boost converter (Conventional 1) which uses 1.0 V operating voltage. On the other hand, by using the same ReRAM sector write time, the proposed boost converter reduces 49% circuit area and 46% energy consumption compared with a conventional two-stage boost converter (Conventional 2). In addition, by using the proposed boost converter, the operating voltage, V DD, can be reduced to 0.6 V. The lowest 159 nJ energy consumption can be obtained when V DD is 0.7 V.

  7. Distribution of Voltage-Gated Sodium Channel (Nav) Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides

    OpenAIRE

    Sayono Sayono; Anggie Puspa Nur Hidayati; Sukmal Fahri; Didik Sumanto; Edi Dharmana; Suharyo Hadisaputro; Puji Budi Setia Asih; Din Syafruddin

    2016-01-01

    The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNa V gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide...

  8. Team-oriented Adaptive Droop Control for Autonomous AC Microgrids

    DEFF Research Database (Denmark)

    Shafiee, Qobad; Nasirian, Vahidreza; Guerrero, Josep M.;

    2014-01-01

    This paper proposes a distributed control strategy for voltage and reactive power regulation in ac Microgrids. First, the control module introduces a voltage regulator that maintains the average voltage of the system on the rated value, keeping all bus voltages within an acceptable range. Dynamic...... consensus protocol is used to estimate the average voltage across the Microgrid. This estimation is further utilized by the voltage regulator to elevate/lower the voltage-reactive power (Q-E) droop characteristic, compensating the drop caused by the droop mechanism. The second module, the reactive power...... regulator, dynamically fine-tunes the Q-E coefficients to handle the proportional reactive power sharing. Accordingly, locally supplied reactive power of any source is compared with neighbor sources and the local droop coefficient is adjusted to mitigate and, ultimately, eliminate the load mismatch...

  9. 46 CFR 111.12-7 - Voltage regulation and parallel operation.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Voltage regulation and parallel operation. 111.12-7... ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Generator Construction and Circuits § 111.12-7 Voltage regulation and parallel operation. Voltage regulation and parallel operation must meet: (a) For AC systems: sections...

  10. Digital model for harmonic interactions in AC/DC/AC systems

    Energy Technology Data Exchange (ETDEWEB)

    Guarini, A.P.; Rangel, R.D.; Pilotto, L.A.S.; Pinto, R.J.; Passos Junior, R. [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil)

    1994-12-31

    The main purpose of this paper is to present a model for calculation of HVdc converter harmonics taking into account the influence of the harmonic interactions between the ac systems in dc link transmissions. The ideas and methodologies used in the model development take into account the dc current ripple and ac voltage distortion in the ac systems. The theory of switching functions is applied to contemplate for the frequency conversions between the ac and dc sides, in an iterative process. It is possible then to obtain, even in balanced situations, non-characteristic harmonics that are produced by frequencies originated in the other terminal, which can be significant in a strongly coupled system, such as back-to-back configuration. (author) 9 refs., 3 figs.

  11. Ligustrazine inhibits high voltage-gated Ca2+ and TTX-resistant Na+ channels of primary sensory neuron and thermal nociception in the rat:a study on peripheral mechanism

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Objective Ligustrazine, also named as tetramethylpyrazine, is a compound purified from Ligusticum chuanxiong hort and has ever been testified to be a calcium antagonist. The present investigation was to determine the antinociceptive effect of ligustrazine and, if any, the peripheral ionic mechanism involved. Methods Paw withdrawal Latency(PWL) to noxious heating was measured in vivo and whole-cell patch recording was performed on small dorsal root ganglion (DRG) neurons. Results Intraplantar injection of ligustrazine (0.5 mg in 25 μl) significantly prolonged the withdrawal latency of ipsilateral hindpaw to noxious heating in the rat. Ligustrazine not only reversibly inhibited high-voltage gated calcium current of dorsal root ganglion (DRG) neuron in dose-dependent manner with IC50 of 1.89 mmol/L, but also decreased tetrodotoxin (TTX) -resistant sodium current in relatively selective and dose-dependent manner with IC50 of2.49 mmol/L. Conclusion The results suggested that ligustrazine could elevate the threshold of thermal nociception through inhibiting the high-voltage gated calcium current and TTX-resistant sodium current of DRG neuron .in the rat.

  12. 转cry1Ac玉米对亚洲玉米螟的抗性评价%Evaluating transgenic crylAc maize for resistance to Ostrinia furnacalis (Guenee)

    Institute of Scientific and Technical Information of China (English)

    王培; 何康来; 王振营; 王应伦

    2012-01-01

    目标性状的有效性评价是转Bt基因抗虫玉米研发和安全性评价研究的重要内容之一。采用酶联免疫吸附剂测定(ELISA)、室内生测和田间人工接虫鉴定研究了转cry1Ac玉米纯合群体BT-X和分离群体BT-38、BT-181、BT-43、BT-105等转化事件Cry1Ac蛋白的表达量以及对亚洲玉米螟Ostrinia furnacalis(Guenée)的室内杀虫和田间抗虫效果。转cry1Ac玉米鲜组织中Cry1Ac蛋白含量在44.07~438.00 ng/g之间,不同转化事件及不同组织之间差异显著,其中BT-X鲜花丝中Bt蛋白表达量显著低于未展开心叶。室内生测试验中除BT-43与对照没有显著差异外,取食其它转基因玉米心叶的亚洲玉米螟初孵幼虫6或7天的存活率为0~15.3%,显著低于非转基因对照;取食夏播BT-X鲜花丝6天的幼虫存活率为62.5%,显著低于Bt11及非转基因对照。田间心叶期接虫鉴定显示BT-X高抗亚洲玉米螟。说明转cry1Ac玉米BT-X、BT-181、BT-38和BT-105对亚洲玉米螟有很高的杀虫作用,BT-X田间抗虫效果良好。%Evaluating transgenic Bt maize for resistance to target insect is a key component of research and development as well as the environmental safety assessment of insect resistant transgenic maize. Effi- cacy of transgenic crylAc maize, events BT-X (homozygote) and BT-38, BT-181, BT43, and BT-105 (segregation populations) , expressing CrylAc protein, were evaluated both in the laboratory and in the field for controlling the Asian core borer (ACB), Ostrinia furnacalis (Guen~e). Enzyme-linked immu- nosorbent assays was exploited to quantify Cryl Ac protein expressing levels in fresh whorl leaves and silks of transgenic crylAc maize plants. The expression levels of CrylAc protein were significantly different among the events in the whorl leaves and silks, ranged from 44.07 to 438. 00 ng/g fresh weight of the tis- sue. In addition, the expression level of Cryl Ac protein was significantly low in the silk than in

  13. ACAC Converters for UPS

    Directory of Open Access Journals (Sweden)

    Rusalin Lucian R. Păun

    2008-05-01

    Full Text Available This paper propose a new control technique forsingle – phase ACAC converters used for a on-line UPSwith a good dynamic response, a reduced-partscomponents, a good output characteristic, a good powerfactorcorrection(PFC. This converter no needs anisolation transformer. A power factor correction rectifierand an inverter with the proposed control scheme has beendesigned and simulated using Caspoc2007, validating theconcept.

  14. Three-phase AC-AC power converters based on matrix converter topology matrix-reactance frequency converters concept

    CERN Document Server

    Szczesniak, Pawel

    2013-01-01

    AC voltage frequency changes is one of the most important functions of solid state power converters. The most desirable features in frequency converters are the ability to generate load voltages with arbitrary amplitude and frequency, sinusoidal currents and voltages waveforms; the possibility of providing unity power factor for any load; and, finally, a simple and compact power circuit. Over the past decades, a number of different frequency converter topologies have appeared in the literature, but only the converters with either a voltage or current DC link are commonly used in industrial app

  15. Internal Tandem Duplication in FLT3 Attenuates Proliferation and Regulates Resistance to the FLT3 Inhibitor AC220 by Modulating p21Cdkn1a and Pbx1 in Hematopoietic Cells.

    Directory of Open Access Journals (Sweden)

    Mariko Abe

    Full Text Available Internal tandem duplication (ITD mutations in the Fms-related tyrosine kinase 3 (FLT3 gene (FLT3-ITD are associated with poor prognosis in patients with acute myeloid leukemia (AML. Due to the development of drug resistance, few FLT3-ITD inhibitors are effective against FLT3-ITD+ AML. In this study, we show that FLT3-ITD activates a novel pathway involving p21Cdkn1a (p21 and pre-B cell leukemia transcription factor 1 (Pbx1 that attenuates FLT3-ITD cell proliferation and is involved in the development of drug resistance. FLT3-ITD up-regulated p21 expression in both mouse bone marrow c-kit+-Sca-1+-Lin- (KSL cells and Ba/F3 cells. The loss of p21 expression enhanced growth factor-independent proliferation and sensitivity to cytarabine as a consequence of concomitantly enriching the S+G2/M phase population and significantly increasing the expression of Pbx1, but not Evi-1, in FLT3-ITD+ cells. This enhanced cell proliferation following the loss of p21 was partially abrogated when Pbx1 expression was silenced in FLT3-ITD+ primary bone marrow colony-forming cells and Ba/F3 cells. When FLT3-ITD was antagonized with AC220, a selective inhibitor of FLT3-ITD, p21 expression was decreased coincident with Pbx1 mRNA up-regulation and a rapid decline in the number of viable FLT3-ITD+ Ba/F3 cells; however, the cells eventually became refractory to AC220. Overexpressing p21 in FLT3-ITD+ Ba/F3 cells delayed the emergence of cells that were refractory to AC220, whereas p21 silencing accelerated their development. These data indicate that FLT3-ITD is capable of inhibiting FLT3-ITD+ cell proliferation through the p21/Pbx1 axis and that treatments that antagonize FLT3-ITD contribute to the subsequent development of cells that are refractory to a FLT3-ITD inhibitor by disrupting p21 expression.

  16. Distribution of Voltage-Gated Sodium Channel (Nav) Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides.

    Science.gov (United States)

    Sayono, Sayono; Hidayati, Anggie Puspa Nur; Fahri, Sukmal; Sumanto, Didik; Dharmana, Edi; Hadisaputro, Suharyo; Asih, Puji Budi Setia; Syafruddin, Din

    2016-01-01

    The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNaV gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide susceptibility tests demonstrated Ae, aegypti resistance to the pyrethroids, with mortality rates ranging from 1.6%-15.2%. Three non-synonymous polymorphisms (S989P, V1016G and F1534C) and one synonymous polymorphism (codon 982) were detected in the AaNaV gene. Eight AaNaV alleles were observed in specimens from Central Java. Allele 3 (SGF) and allele 7 (PGF) represent the most common alleles found and demonstrated strong associations with resistance to pyrethroids (OR = 2.75, CI: 0.97-7.8 and OR = 7.37, CI: 2.4-22.5, respectively). This is the first report of 8 Ae. aegypti AaNaV alleles, and it indicates the development of resistance in Ae. aegypti in response to pyrethroid insecticide-based selective pressure. These findings strongly suggest the need for an appropriate integrated use of insecticides in the region. The 989P, 1016G and 1534C polymorphisms in the AaNaV gene are potentially valuable molecular markers for pyrethroid insecticide resistance monitoring.

  17. Distribution of Voltage-Gated Sodium Channel (Nav Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides.

    Directory of Open Access Journals (Sweden)

    Sayono Sayono

    Full Text Available The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNaV gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide susceptibility tests demonstrated Ae, aegypti resistance to the pyrethroids, with mortality rates ranging from 1.6%-15.2%. Three non-synonymous polymorphisms (S989P, V1016G and F1534C and one synonymous polymorphism (codon 982 were detected in the AaNaV gene. Eight AaNaV alleles were observed in specimens from Central Java. Allele 3 (SGF and allele 7 (PGF represent the most common alleles found and demonstrated strong associations with resistance to pyrethroids (OR = 2.75, CI: 0.97-7.8 and OR = 7.37, CI: 2.4-22.5, respectively. This is the first report of 8 Ae. aegypti AaNaV alleles, and it indicates the development of resistance in Ae. aegypti in response to pyrethroid insecticide-based selective pressure. These findings strongly suggest the need for an appropriate integrated use of insecticides in the region. The 989P, 1016G and 1534C polymorphisms in the AaNaV gene are potentially valuable molecular markers for pyrethroid insecticide resistance monitoring.

  18. A Typical Misunderstanding of Medium and Small-Size and High Efficient Low-Voltage AC Motor Energy Saving Applications%中小型低压交流高效电机节能应用的典型误区

    Institute of Scientific and Technical Information of China (English)

    陈伟华; 吴艳红; 张维

    2012-01-01

    我国前后共开发了五代中小型低压交流电机及其派生产品,虽然效率水平不断提高,但是由于电机系统节能不仅与电机本身效率的提高有关,还与电机及负载特性的匹配、速度调节控制模式等密切相关.在电机系统节能改造中,如果仅采用高效电机进行简单替换,或者是将原电机系统加装变频器等控制装置进行简易维护,很可能造成节能效果不理想.将一些电机系统节能改造中经常出现的典型误区进行分析,提出了更好的解决方案.%AC motor and its derived products which was and medium and small-size low-voltage for the fifth generation were developed in our country, although the efficiency had improved continuously, but the motor system energy saving was not only related with the improved motor efficiency, but also closely related to the match of motor and load characteristics, and the control mode in the speed regulator. In the motor energy-saving system, if only high-efficiency motor simple substitution or the original motor system such as the installation of the inverter control equipment for easy maintenance was likely to cause unsatisfactory results of the energy saving. Analyzed typical misunderstanding which was often appear in the motor system energy-saving, and proposed a better solution.

  19. Interstrand contact resistance and AC loss of a 48-strands Nb3Sn CIC conductor with a Cr/Cr-oxide coating

    NARCIS (Netherlands)

    Nijhuis, Arend; Kate, ten Herman H.J.; Pantsyrny, Victor; Shikov, Alexander K.

    2000-01-01

    The interstrand contact resistance (Rc) between crossing strands in Cable-In-Conduit Conductors (CICC's) determines the coupling loss and the stability against local disturbances. The surface oxidation, surface roughness and micro-scale sliding of the contact surfaces are key parameters in the Rc. T

  20. Interstrand contact resistance and AC loss of a 48-strands Nb3Sn CIC conductor with a Cr/Cr-oxide coating

    NARCIS (Netherlands)

    Nijhuis, Arend; ten Kate, Herman H.J.; Pantsyrny, Victor; Shikov, Alexander K.

    2000-01-01

    The interstrand contact resistance (Rc) between crossing strands in Cable-In-Conduit Conductors (CICC's) determines the coupling loss and the stability against local disturbances. The surface oxidation, surface roughness and micro-scale sliding of the contact surfaces are key parameters in the Rc.

  1. Down-regulation of aminopeptidase N and ABC transporter subfamily G transcripts in Cry1Ab and Cry1Ac resistant Asian corn borer, Ostrina furnacalis (Lepidoptera: Crambidae)

    Science.gov (United States)

    Bacillus thuringiensis (Bt) crystalline protein (Cry) toxins cause mortality by a mechanism involving pore formation or signal transduction following toxin binding to receptors along the midgut lumen of susceptible insects, but this mechanism and mutations therein that lead to resistance remain poor...

  2. Effect of applied bias voltage on corrosion-resistance for TiC{sub 1-x}N{sub x} and Ti{sub 1-x}Nb{sub x}C{sub 1-y}N{sub y} coatings

    Energy Technology Data Exchange (ETDEWEB)

    Caicedo, J.C., E-mail: Jcesarca@calima.univalle.edu.co [Department of Physics, Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360 Cali (Colombia); Department de Fisica Aplicada i Optica, Universitat de Barcelona, Catalunya (Spain); Amaya, C. [Department of Physics, Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360 Cali (Colombia); Laboratorio de Recubrimientos Duros DT-ASTIN SENA, Cali (Colombia); Yate, L. [Department de Fisica Aplicada i Optica, Universitat de Barcelona, Catalunya (Spain); Aperador, W.; Zambrano, G.; Gomez, M.E. [Department of Physics, Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360 Cali (Colombia); Alvarado-Rivera, J.; Munoz-Saldana, J. [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Queretaro (Mexico); Prieto, P. [Department of Physics, Universidad del Valle, Ciudad Universitaria Melendez, A.A. 25360 Cali (Colombia); Centro de Excelencia en Nuevos Materiales, Calle 13 100-00 Edificio 320, espacio 1026, Cali (Colombia)

    2010-02-15

    Corrosion-resistance behavior of titanium carbon nitride (Ti-C-N) and titanium niobium carbon nitride (Ti-Nb-C-N) coatings deposited onto Si(1 0 0) and AISI 4140 steel substrates via r.f. magnetron sputtering process was analyzed. The coatings in contact with a solution of sodium chloride at 3.5% were studied by Tafel polarization curves and impedance spectroscopy methods (EIS). Variations of the bias voltage were carried out for each series of deposition to observe the influence of this parameter upon the electrochemical properties of the coatings. The introduction of Nb in the ternary Ti-C-N film was evaluated via X-ray diffraction (XRD) analysis. The structure was characterized by using Raman spectroscopy to identify ternary and quaternary compounds. Surface corrosion processes were characterized using optical microscopy and scanning electron microscopy (SEM). XRD results show conformation of the quaternary phase, change in the strain of the film, and lattice parameter as the effect of the Nb inclusion. The main Raman bands were assigned to interstitial phases and 'impurities' of the coatings. Changes in Raman intensities were attributed to the incorporation of niobium in the Ti-C-N structure and possibly to resonance enhancement. Finally, the corrosion data obtained for Ti-C-N were compared with the results of corrosion tests of Ti-Nb-C-N coating. The results obtained showed that the incorporation of niobium to Ti-C-N coatings led to an increase in the corrosion-resistance. On another hand, an increase in the bias voltage led to a decrease in the corrosion-resistance for both Ti-C-N and Ti-Nb-C-N coatings.

  3. 暂态边界电压法在线测试全钒液流电池阻抗%On-line resistance measurement for all vanadium redox flow battery by transient-boundary voltage method

    Institute of Scientific and Technical Information of China (English)

    潘建欣; 廖玲芝; 谢晓峰; 王树博; 王金海; 尚玉明; 周涛

    2012-01-01

    国内首次采用暂态边界电压法在线研究了全钒液流电池(VRB)的特性,建立了由电压源、电阻以及一个电阻与电容并联的3部分串联而成的等效电路模型;研究了电流密度和荷电状态(SOC)对等效电路元件的影响。实验结果表明,极化阻抗随电流密度的增加有轻微下降,在充电初期和放电末期达到最大值。与极化阻抗相比,充、放电过程中的欧姆阻抗最大,是导致电压损失的主要因素,分别为1.905Ω.cm2和2.139Ω.cm2,暂态边界电压法是一种简单且有效的表征全钒液流电池性能的新方法。%A single cell of vanadium redox flow battery(VRB) was investigated on-line by the transient-boundary voltage method.An equivalent circuit model was established using the voltage source,resistor,and a resistor in parallel with the capacitance of three-part series.The effects of current density and state of charge(SOC) on equivalent circuit components values were investigated.The experimental results showed that the polarization resistance decreased slightly with increasing current density,and reached its maximum in the beginning of charge and the end of discharge.Compared with polarization resistance,ohm impedance in the charge/discharge process was the highest respectively 1.905 cm2and 2.139 cm2.It was the main factor leading to voltage loss.The transient boundary voltage method is a simple and effective way of characterizing performance of vanadium redox flow battery.

  4. ACS: ALMA Common Software

    Science.gov (United States)

    Chiozzi, Gianluca; Šekoranja, Matej

    2013-02-01

    ALMA Common Software (ACS) provides a software infrastructure common to all ALMA partners and consists of a documented collection of common patterns and components which implement those patterns. The heart of ACS is based on a distributed Component-Container model, with ACS Components implemented as CORBA objects in any of the supported programming languages. ACS provides common CORBA-based services such as logging, error and alarm management, configuration database and lifecycle management. Although designed for ALMA, ACS can and is being used in other control systems and distributed software projects, since it implements proven design patterns using state of the art, reliable technology. It also allows, through the use of well-known standard constructs and components, that other team members whom are not authors of ACS easily understand the architecture of software modules, making maintenance affordable even on a very large project.

  5. Advanced power electronics converters PWM converters processing AC voltages

    CERN Document Server

    dos Santos, Euzeli

    2014-01-01

    This book covers power electronics, in depth, by presenting the basic principles and application details, which can be used both as a textbook and reference book.  Introduces a new method to present power electronics converters called Power Blocks Geometry. Applicable for courses focusing on power electronics, power electronics converters, and advanced power converters. Offers a comprehensive set of simulation results to help understand the circuits presented throughout the book

  6. Analysis of AC Low-Voltage Energy Harvesting

    Science.gov (United States)

    2014-09-01

    Project (0704-0188) Washington DC 20503. 1. AGENCY USE ONLY (Leave blank) 2. REPORT DATE September 2014 3. REPORT TYPE AND DATES COVERED...current behavior of the inductor current (from [10]). ..............................9  Figure 10.  Buck chopper modes with respect to duty cycle (from...Cycle DC Direct Current DCM Discontinuous Conduction Mode sF Frequency GND Ground Hz Hertz I Current bridgeI Diode Bridge Current L Inductor

  7. Distribution of Voltage-Gated Sodium Channel (Nav) Alleles among the Aedes aegypti Populations In Central Java Province and Its Association with Resistance to Pyrethroid Insecticides

    Science.gov (United States)

    Sayono, Sayono; Hidayati, Anggie Puspa Nur; Fahri, Sukmal; Sumanto, Didik; Dharmana, Edi; Hadisaputro, Suharyo; Asih, Puji Budi Setia; Syafruddin, Din

    2016-01-01

    The emergence of insecticide resistant Aedes aegypti mosquitoes has hampered dengue control efforts. WHO susceptibility tests, using several pyrethroid compounds, were conducted on Ae. aegypti larvae that were collected and raised to adulthood from Semarang, Surakarta, Kudus and Jepara in Java. The AaNaV gene fragment encompassing kdr polymorphic sites from both susceptible and resistant mosquitoes was amplified, and polymorphisms were associated with the resistant phenotype. The insecticide susceptibility tests demonstrated Ae, aegypti resistance to the pyrethroids, with mortality rates ranging from 1.6%–15.2%. Three non-synonymous polymorphisms (S989P, V1016G and F1534C) and one synonymous polymorphism (codon 982) were detected in the AaNaV gene. Eight AaNaV alleles were observed in specimens from Central Java. Allele 3 (SGF) and allele 7 (PGF) represent the most common alleles found and demonstrated strong associations with resistance to pyrethroids (OR = 2.75, CI: 0.97–7.8 and OR = 7.37, CI: 2.4–22.5, respectively). This is the first report of 8 Ae. aegypti AaNaV alleles, and it indicates the development of resistance in Ae. aegypti in response to pyrethroid insecticide-based selective pressure. These findings strongly suggest the need for an appropriate integrated use of insecticides in the region. The 989P, 1016G and 1534C polymorphisms in the AaNaV gene are potentially valuable molecular markers for pyrethroid insecticide resistance monitoring. PMID:26939002

  8. Magnetic irreversibility in granular superconductors: ac susceptibility study

    Energy Technology Data Exchange (ETDEWEB)

    Perez, F.; Obradors, X.; Fontcuberta, J. (ICMAB, CSIC, Bellaterra, Barcelona (Spain)); Vallet, M.; Gonzalez-Calbet, J. (Lab. Magnetismo Aplicado, RENFE-U.C. Madrid, Las Matas (Spain))

    1991-12-01

    Ac susceptibility measurements of a ceramic weak-coupled superconductor in very low ac fields (2mG, 111Hz) are reported. We present evidence for the observation of the magnetic irreversibility following a ZFC-FC thermal cycling by means of ac susceptibilty measurements. It is shown that this technique also reflect local magnetic field effects in granular superconductors, as previously suggested in microwave surface resistance and I-V characteristics. (orig.).

  9. Local Voltage Support from Distributed Energy Resources to Prevent Air Conditioner Motor Stalling

    Energy Technology Data Exchange (ETDEWEB)

    Baone, Chaitanya A [ORNL; Xu, Yan [ORNL; Kueck, John D [ORNL

    2010-01-01

    Microgrid voltage collapse often happens when there is a high percentage of low inertia air-conditioning (AC) motors in the power systems. The stalling of the AC motors results in Fault Induced Delayed Voltage Recovery (FIDVR). A hybrid load model including typical building loads, AC motor loads, and other induction motor loads is built to simulate the motoring stalling phenomena. Furthermore, distributed energy resources (DE) with local voltage support capability are utilized to boost the local bus voltage during a fault, and prevent the motor stalling. The simulation results are presented. The analysis of the simulation results show that local voltage support from multiple DEs can effectively and economically solve the microgrid voltage collapse problem.

  10. The Influence of Uncompensated Solution Resistance on the Determination and Standard Electrochemical Rate Constants Using Cyclic Voltammetry, and Some Comparisons with AC Voltammetry.

    Science.gov (United States)

    1987-09-25

    rate constants, k2r using cyclic voltametry . The res tss are expressed in terms of systematic deviations oP sapparent measured" rate constants, k~b(app...Classification) The Influence of Uncompensated Solution Resistance on the Determination and Standard Electro- - . chemical Rate Constants Using Cyclic ...Year MonhOy SAGE COUNT FIELD GROUP Sue-GROUP digital simulation analysis, uncompensated solution resis- I A tance, electrochemical rate constants, cyclic

  11. Transient Voltage Recorder

    Science.gov (United States)

    Medelius, Pedro J. (Inventor); Simpson, Howard J. (Inventor)

    2002-01-01

    A voltage transient recorder can detect lightning induced transient voltages. The recorder detects a lightning induced transient voltage and adjusts input amplifiers to accurately record transient voltage magnitudes. The recorder stores voltage data from numerous monitored channels, or devices. The data is time stamped and can be output in real time, or stored for later retrieval. The transient recorder, in one embodiment, includes an analog-to-digital converter and a voltage threshold detector. When an input voltage exceeds a pre-determined voltage threshold, the recorder stores the incoming voltage magnitude and time of arrival. The recorder also determines if its input amplifier circuits clip the incoming signal or if the incoming signal is too low. If the input data is clipped or too low, the recorder adjusts the gain of the amplifier circuits to accurately acquire subsequent components of the lightning induced transients.

  12. Adaptive Voltage Control Strategy for Variable-Speed Wind Turbine Connected to a Weak Network

    DEFF Research Database (Denmark)

    Abulanwar, Elsayed; Hu, Weihao; Chen, Zhe

    2016-01-01

    Significant voltage fluctuations and power quality issues pose considerable constraints on the efficient integration of remotely located wind turbines into weak networks. Besides, 3p oscillations arising from the wind shear and tower shadow effects induce further voltage perturbations during...... continuous operation. This study investigates and analyses the repercussions raised by integrating a doubly-fed induction generator wind turbine into an ac network of different parameters and very weak conditions. An adaptive voltage control (AVC) strategy is proposed to retain voltage constancy...

  13. Relação entre resistência de linhagens tropicais de milho à podridão de espiga e ao acúmulo de fumonisinas provocados por Fusarium verticillioides

    Directory of Open Access Journals (Sweden)

    Adalgisa Thayne Munhoz

    2015-06-01

    Full Text Available A infecção de grãos de milho por Fusarium verticillioides, agente causal da podridão da espiga, pode resultar na produção de micotoxinas do grupo das fumonisinas. A resistência genética é a forma de controle mais eficiente dessa enfermidade. Assim, o objetivo do trabalho foi buscar fontes de resistência em linhagens de milho tropical à F. verticillioides e à produção de fumonisinas. Seis linhagens tropicais de milho, três, pré-classificadas como resistentes e três, pré-classificadas como suscetíveis à F. verticillioides, foram submetidas à inoculação do patógeno e posteriormente, avaliadas quanto à severidade da podridão de espiga, incidência de grãos sintomáticos e concentração de fumonisinas. Os resultados mostraram que as linhagens R1 e R3 apresentaram alta resistência à infecção do patógeno. No entanto, apenas a R3 foi resistente ao acúmulo de fumonisinas. Dessa forma, sugere-se que a ausência de relação entre intensidade da doença e níveis de fumonisinas seja fator inerente desse patossistema. Assim, não é possível assegurar que grãos assintomáticos quanto à infecção por F. verticillioides, estejam livres de contaminação por fumonisinas.

  14. Electrode voltage fall and total voltage of a transient arc

    Science.gov (United States)

    Valensi, F.; Ratovoson, L.; Razafinimanana, M.; Masquère, M.; Freton, P.; Gleizes, A.

    2016-06-01

    This paper deals with an experimental study of the components of a transient arc total voltage with duration of a few tens of ms and a current peak close to 1000 A. The cathode tip is made of graphite whereas the flat anode is made either of copper or of graphite; the electrodes gap is a few mm. The analysis of the electrical parameters is supported and validated by fast imaging and by two models: the first one is a 2D physical model of the arc allowing to calculate both the plasma temperature field and the arc voltage; the second model is able to estimate the transient heating of the graphite electrode. The main aim of the study was to detect the possible change of the cathode voltage fall (CVF) during the first instants of the arc. Indeed it is expected that during the first ms the graphite cathode is rather cool and the main mechanism of the electron emission should be the field effect emission, whereas after several tens of ms the cathode is strongly heated and thermionic emission should be predominant. We have observed some change in the apparent CVF but we have shown that this apparent change can be attributed to the variation of the solid cathode resistance. On the other hand, the possible change of CVF corresponding to the transition between a ‘cold’ and a ‘hot’ cathode should be weak and could not be characterized considering our measurement uncertainty of about 2 V. The arc column voltage (ACV) was estimated by subtracting the electrode voltage fall from the total arc voltage. The experimental transient evolution of the ACV is in very good agreement with the theoretical variation predicted by the model, showing the good ability of the model to study this kind of transient arc.

  15. Alternating current breakdown voltage of ice electret

    Science.gov (United States)

    Oshika, Y.; Tsuchiya, Y.; Okumura, T.; Muramoto, Y.

    2017-09-01

    Ice has low environmental impact. Our research objectives are to study the availability of ice as a dielectric insulating material at cryogenic temperatures. We focus on ferroelectric ice (iceXI) at cryogenic temperatures. The properties of iceXI, including its formation, are not clear. We attempted to obtain the polarized ice that was similar to iceXI under the applied voltage and cooling to 77 K. The polarized ice have a wide range of engineering applications as electronic materials at cryogenic temperatures. This polarized ice is called ice electret. The structural difference between ice electret and normal ice is only the positions of protons. The effects of the proton arrangement on the breakdown voltage of ice electret were shown because electrical properties are influenced by the structure of ice. We observed an alternating current (ac) breakdown voltage of ice electret and normal ice at 77 K. The mean and minimum ac breakdown voltage values of ice electret were higher than those of normal ice. We considered that the electrically weak part of the normal ice was improved by applied a direct electric field.

  16. Power Capability in Low Voltage DC Distribution Systems

    Directory of Open Access Journals (Sweden)

    C.O. Gecan

    2009-12-01

    Full Text Available Recent developments in power electronics components enable the use of power electronics in Low Voltage (LV networks. This development makes the model of a Low Voltage Direct Current (LVDC distribution system possible. The technical and economical benefits of this technology make possible the alternative hypothesis of using DC instead of AC distribution systems. Some aspects, such as increasing the capability of the existing lines, interconnecting distributed generation units and even supplying in DC some loads are creating additional requirements of using a LVDC distribution system. The paper presents some general considerations regarding cables used in a LVAC distribution system and different line reconfigurations witch enable the use of cobles in a LVDC distribution system. The reconfigurations are presented in respect of the DC network topologies: unipolar and bipolar. The central aim of this paper is to investigate capability of power transmission and to calculate the transmission distance for cables used in Low Voltage AC and DC distribution systems. Capability computation is considered in respect of two constrains imposed in the cables cross section selection: cable thermal limit and the maximum allowable voltage drop. Cable thermal limit is represented in calculations by the maximum rated current. The equations used to calculate the power capability are presented for single-phase and threephase AC networks and unipolar and bipolar DC networks. Based on these equations, comparisons between power capability of cables with different cross sections used in Low Voltage DC and AC distribution systems are realized and presented.

  17. Maximum permissible voltage of YBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Wen, J.; Lin, B.; Sheng, J.; Xu, J.; Jin, Z. [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Hong, Z., E-mail: zhiyong.hong@sjtu.edu.cn [Department of Electrical Engineering, Shanghai Jiao Tong University, Shanghai (China); Wang, D.; Zhou, H.; Shen, X.; Shen, C. [Qingpu Power Supply Company, State Grid Shanghai Municipal Electric Power Company, Shanghai (China)

    2014-06-15

    Highlights: • We examine three kinds of tapes’ maximum permissible voltage. • We examine the relationship between quenching duration and maximum permissible voltage. • Continuous I{sub c} degradations under repetitive quenching where tapes reaching maximum permissible voltage. • The relationship between maximum permissible voltage and resistance, temperature. - Abstract: Superconducting fault current limiter (SFCL) could reduce short circuit currents in electrical power system. One of the most important thing in developing SFCL is to find out the maximum permissible voltage of each limiting element. The maximum permissible voltage is defined as the maximum voltage per unit length at which the YBCO coated conductors (CC) do not suffer from critical current (I{sub c}) degradation or burnout. In this research, the time of quenching process is changed and voltage is raised until the I{sub c} degradation or burnout happens. YBCO coated conductors test in the experiment are from American superconductor (AMSC) and Shanghai Jiao Tong University (SJTU). Along with the quenching duration increasing, the maximum permissible voltage of CC decreases. When quenching duration is 100 ms, the maximum permissible of SJTU CC, 12 mm AMSC CC and 4 mm AMSC CC are 0.72 V/cm, 0.52 V/cm and 1.2 V/cm respectively. Based on the results of samples, the whole length of CCs used in the design of a SFCL can be determined.

  18. Challenges for High Voltage Testing of UHV Equipment

    Institute of Scientific and Technical Information of China (English)

    Ernst Gockenbach

    2011-01-01

    The increase of voltage level for AC and DC transmission systems requires some changes in the high voltage testing for Ultra High Voltage (UHV) equipment. After a short description of the coordination work in the standard- ization bodies the requirements for UHV equipment are mentioned. The main points concerning high voltage testing of UHV equipment are the impulse shape of standard lightning impulse voltage, the evaluation of the test voltage for impulses with oscillations or overshoot near the peak and the time parameter of switching impulses. The linearity check of the measuring devices, the proximity effect, the wet tests and the atmospheric correction factors are further points to be discussed concerning testing of UHV equipment.

  19. Intertied ac–ac microgrids with autonomous power import and export

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Wang, Peng

    2015-01-01

    Intertied ac–ac microgrids offer many potential benefits like flexible frequency and voltage selection, reserve sharing and enhanced supply reliability. Operating them is however challenging due to their larger size and presence of more power converters with different responsibilities. These comp......Intertied ac–ac microgrids offer many potential benefits like flexible frequency and voltage selection, reserve sharing and enhanced supply reliability. Operating them is however challenging due to their larger size and presence of more power converters with different responsibilities...

  20. Recent applications of AC electrokinetics in biomolecular analysis on microfluidic devices.

    Science.gov (United States)

    Sasaki, Naoki

    2012-01-01

    AC electrokinetics is a generic term that refers to an induced motion of particles and fluids under nonuniform AC electric fields. The AC electric fields are formed by application of AC voltages to microelectrodes, which can be easily integrated into microfluidic devices by standard microfabrication techniques. Moreover, the magnitude of the motion is large enough to control the mass transfer on the devices. These advantages are attractive for biomolecular analysis on the microfluidic devices, in which the characteristics of small space and microfluidics have been mainly employed. In this review, I describe recent applications of AC electrokinetics in biomolecular analysis on microfluidic devices. The applications include fluid pumping and mixing by AC electrokinetic flow, and manipulation of biomolecules such as DNA and proteins by various AC electrokinetic techniques. Future prospects for highly functional biomolecular analysis on microfluidic devices with the aid of AC electrokinetics are also discussed.

  1. Automatic voltage imbalance detector

    Science.gov (United States)

    Bobbett, Ronald E.; McCormick, J. Byron; Kerwin, William J.

    1984-01-01

    A device for indicating and preventing damage to voltage cells such as galvanic cells and fuel cells connected in series by detecting sequential voltages and comparing these voltages to adjacent voltage cells. The device is implemented by using operational amplifiers and switching circuitry is provided by transistors. The device can be utilized in battery powered electric vehicles to prevent galvanic cell damage and also in series connected fuel cells to prevent fuel cell damage.

  2. PREVENTION AND CONTROL OF TUBERCULOSIS *A.C. Okoh ...

    African Journals Online (AJOL)

    drclement

    *A.C. Okoh. Department of Community Health, University of Teaching Hospital Benin City,. Nigeria ... Organization. (WHO) ... Control is the reduction of the prevalence ... behavioural changes, especially in ... stimulate an acquired resistance to.

  3. Control of VSC-HVDC in offshore AC islands with wind power plants: Comparison of two alternatives

    DEFF Research Database (Denmark)

    Zeni, Lorenzo; Hesselbæk, Bo; Sørensen, Poul Ejnar;

    2015-01-01

    The subject of this paper is the control of offshore AC collection and export networks behind a voltage source converter based high voltage direct current transmission system. The inertia-less nature of such grids makes the control of voltages and power flows potentially more flexible, but at the...

  4. Multiple High Voltage Pulse Stressing of Polymer Thick Film Resistors

    Directory of Open Access Journals (Sweden)

    Busi Rambabu

    2014-01-01

    Full Text Available The purpose of this paper is to study high voltage interactions in polymer thick film resistors, namely, polyvinyl chloride- (PVC- graphite thick film resistors, and their applications in universal trimming of these resistors. High voltages in the form of impulses for various pulse durations and with different amplitudes have been applied to polymer thick film resistors and we observed the variation of resistance of these resistors with high voltages. It has been found that the resistance of polymer thick film resistors decreases in the case of higher resistivity materials and the resistance of polymer thick film resistor increases in the case of lower resistivity materials when high voltage impulses are applied to them. It has been also found that multiple high voltage pulse (MHVP stressing can be used to trim the polymer thick film resistors either upwards or downwards.

  5. Mixed voltage VLSI design

    Science.gov (United States)

    Panwar, Ramesh; Rennels, David; Alkalaj, Leon

    1993-01-01

    A technique for minimizing the power dissipated in a Very Large Scale Integration (VLSI) chip by lowering the operating voltage without any significant penalty in the chip throughput even though low voltage operation results in slower circuits. Since the overall throughput of a VLSI chip depends on the speed of the critical path(s) in the chip, it may be possible to sustain the throughput rates attained at higher voltages by operating the circuits in the critical path(s) with a high voltage while operating the other circuits with a lower voltage to minimize the power dissipation. The interface between the gates which operate at different voltages is crucial for low power dissipation since the interface may possibly have high static current dissipation thus negating the gains of the low voltage operation. The design of a voltage level translator which does the interface between the low voltage and high voltage circuits without any significant static dissipation is presented. Then, the results of the mixed voltage design using a greedy algorithm on three chips for various operating voltages are presented.

  6. POWER FACTOR IMPROVEMENT IN THREE PHASE AC-AC CONVERTER THROUGH MODIFIED SPWM

    Directory of Open Access Journals (Sweden)

    P.VASUKI,

    2011-02-01

    Full Text Available Recently, a new generation of ac-ac single-phase and three-phase power converters with more commutations per half cycle has been proposed for ac power due to the increasing availability and power capability of high frequency controlled-on and off power emiconductor switching devices. This paper presents three phase ac-acconverter whose control strategy is based on modified sinusoidal ulse-width modulation switching technique. As majority of the industrial loads are being inductive, the power factor is less. To improve the power factor, the delayed current is shifted to the input voltage, through a modification of the classical sinusoidal pulse width modulation switching technique. In this way, the decrease in the phase angle between the input current and voltage is feasible, and consequently, high cost compensation capacitors can be avoided. The improvement of power factor through this switching technique on the proposed converter is investigated and verified via simulation using the software Matlab/Simulink.

  7. Vector control of three-phase AC machines system development in the practice

    CERN Document Server

    Quang, Nguyen Phung

    2008-01-01

    Covers the area of vector control of 3-phase AC machines, in particular induction motors with squirrel-cage rotor, permanent excited synchronous motors and doubly-fed induction machines. This title summarizes the basic structure of a field-oriented controlled 3-phase AC drive and grid voltage orientated controlled wind power plant.

  8. harmonics: generation and suppression in ac system networks

    African Journals Online (AJOL)

    2012-11-03

    Nov 3, 2012 ... HARMONICS: GENERATION AND SUPPRESSION IN AC. SYSTEM NETWORKS .... If Vs = 295V; Z = (8 + j6)Ω and δ = 2π/3, the output voltage, Vo and ... tor current assume the characteristics shown in figure. 8. The output ...

  9. Novel dielectric reduces corona breakdown in ac capacitors

    Science.gov (United States)

    Loehner, J. L.

    1972-01-01

    Dielectric system was developed which consists of two layers of 25-gage paper separated by one layer of 50-gage polypropylene to reduce corona breakdown in ac capacitors. System can be used in any alternating current application where constant voltage does not exceed 400 V rms. With a little research it could probably be increased to 700 to 800 V rms.

  10. Rethinking Rectification: AC-DC Power Supply in Package

    DEFF Research Database (Denmark)

    Pejtersen, Jens; Knott, Arnold; Jørgensen, Ivan Harald Holger

    Rectification of AC mains voltage is almost exclusively implemented with passive diode bridge rectifiers for power applications below 100 W. The diode bridge rectifier is reliable, cost effective and easy to use. But it is also lossy, nonlinear and passive. Thus reducing the power conversion...

  11. Conductivity measurements with trapezoidal a.c. magnetic fields

    NARCIS (Netherlands)

    Gijsbertse, E.A.; Klundert, van de L.J.M.

    1981-01-01

    The inductive response of normal metals to trapezoidal a.c. fields is studied theoretically as well as experimentally. A method is presented to determine the conductivity and its magnetic induction dependence from the decay of the induced voltage during periods of constant field. The correctness of

  12. Mitigation of voltage sag, swell and power factor correction using solid-state transformer b

    Directory of Open Access Journals (Sweden)

    M.R. Banaei

    2014-09-01

    Full Text Available This paper presents a novel topology of solid-state transformer (SST. In the design process, the AC/DC, DC/AC and AC/AC converters have been integrated to achieve higher efficiency. To obtain higher efficiency from other SST with DC-link topologies, the AC/DC and DC/AC converters have been integrated in one matrix converter. The proposed SST performs typical functions and has advantages such as power factor correction, voltage sag and swell elimination, voltage flicker reduction and protection capability in fault situations. In addition, it has other benefits such as light weight, low volume and elimination of hazardous liquid dielectrics because it uses medium frequency transformer. The operation and some performances of the proposed SST have been verified by the simulation results.

  13. HIGH VOLTAGE SAFETY MANAGEMENT SYSTEM OF ELECTRIC VEHICLE

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    In order to improve the drivability and energy efficiency of electric vehicle (EV), more and more batteries are connected in series with high voltage which makes it necessary to monitor the electric parameters of high voltage system (HVS) to ensure the high voltage safety. A high voltage safety management system is developed to solve this critical issue. Several key electric parameters including pre-charge, contact resistance, insulation resistance and remaining capacity are monitored and analyzed based on the presented equivalent models. An electronic unit called high voltage safety controller is developed. By the help of hardware-in-loop system, the equivalent models integrated in the high voltage safety controller are validated and the on-line electric parameters monitor strategy is discussed. The real vehicle experiment results indicate that the high voltage safety management system designed is suitable for EV application.

  14. A Switched Capacitor Based AC/DC Resonant Converter for High Frequency AC Power Generation

    Directory of Open Access Journals (Sweden)

    Cuidong Xu

    2015-09-01

    Full Text Available A switched capacitor based AC-DC resonant power converter is proposed for high frequency power generation output conversion. This converter is suitable for small scale, high frequency wind power generation. It has a high conversion ratio to provide a step down from high voltage to low voltage for easy use. The voltage conversion ratio of conventional switched capacitor power converters is fixed to n, 1/n or −1/n (n is the switched capacitor cell. In this paper, A circuit which can provide n, 1/n and 2n/m of the voltage conversion ratio is presented (n is stepping up the switched capacitor cell, m is stepping down the switching capacitor cell. The conversion ratio can be changed greatly by using only two switches. A resonant tank is used to assist in zero current switching, and hence the current spike, which usually exists in a classical switching switched capacitor converter, can be eliminated. Both easy operation and efficiency are possible. Principles of operation, computer simulations and experimental results of the proposed circuit are presented. General analysis and design methods are given. The experimental result verifies the theoretical analysis of high frequency AC power generation.

  15. AC power generation from microbial fuel cells

    Science.gov (United States)

    Lobo, Fernanda Leite; Wang, Heming; Forrestal, Casey; Ren, Zhiyong Jason

    2015-11-01

    Microbial fuel cells (MFCs) directly convert biodegradable substrates to electricity and carry good potential for energy-positive wastewater treatment. However, the low and direct current (DC) output from MFC is not usable for general electronics except small sensors, yet commercial DC-AC converters or inverters used in solar systems cannot be directly applied to MFCs. This study presents a new DC-AC converter system for MFCs that can generate alternating voltage in any desired frequency. Results show that AC power can be easily achieved in three different frequencies tested (1, 10, 60 Hz), and no energy storage layer such as capacitors was needed. The DC-AC converter efficiency was higher than 95% when powered by either individual MFCs or simple MFC stacks. Total harmonic distortion (THD) was used to investigate the quality of the energy, and it showed that the energy could be directly usable for linear electronic loads. This study shows that through electrical conversion MFCs can be potentially used in household electronics for decentralized off-grid communities.

  16. Investigation of edge- and bulk-related resistive switching behaviors and backward-scan effects in SiOx-based resistive switching memory

    Science.gov (United States)

    Chang, Yao-Feng; Ji, Li; Wang, Yanzhen; Chen, Pai-Yu; Zhou, Fei; Xue, Fei; Fowler, Burt; Yu, Edward T.; Lee, Jack C.

    2013-11-01

    Switching characteristics of edge and bulk device structures and an unusual backward-scan effect are investigated in SiOx-based resistive memory. Adding external resistance is found to dramatically affect reset voltage, providing insight into the unique unipolar operation. Non-edge, bulk SiOx-based devices allow flexibility in the fabrication process and hydrogen incorporation improves electroforming and device yield. A backward-scan phenomenon is examined by investigating the DC and AC pulse responses, which defines requirements for ON and OFF programming duration. Circuit-level simulation using a Verilog-A model aids device characterization and programming strategy development for future nonvolatile memory applications.

  17. AcEST: DK950971 [AcEST

    Lifescience Database Archive (English)

    Full Text Available GN=... 37 0.66 tr|B1ACS4|B1ACS4_BALBO DMP1 (Fragment) OS=Balaenoptera borealis ... 37 0.66 tr|B1ACS3|B1ACS3...todon GN=DM... 37 1.1 tr|B1ACT4|B1ACT4_LISBO DMP1 (Fragment) OS=Lissodelphis borealis ... 37 1.1 tr|B1ACS2|B...SSSEEEIQSKNTEMESRRLTVDAY 160 >tr|B1ACS4|B1ACS4_BALBO DMP1 (Fragment) OS=Balaenoptera borealis GN=DMP1 PE=4 S

  18. Cry1Ac抗、感棉铃虫碱性磷酸酯酶(ALP1)的表达量比较%The Expression Level of Alkaline Phosphatase (ALP1) in Cry1Ac-Resistant and Susceptible Cotton Bollworm Helicoverpa armigera Hübner

    Institute of Scientific and Technical Information of China (English)

    张涛; 张丽丽; 魏纪珍; 肖玉涛; 梁革梅; 周瑞阳

    2013-01-01

    [目的]通过比较Cry1Ac抗、感棉铃虫昆虫中肠碱性磷酸酶(ALP1)表达量的差异及抗性棉铃虫取食Cry1Ac蛋白对ALP1表达量的影响,分析ALP1表达量变化与抗性的关系,为进一步明确Bt抗性机制、制定抗性治理策略提供理论依据.[方法]利用实时荧光定量PCR技术,比较敏感棉铃虫、Cry1Ac抗性棉铃虫取食含Cry1Ac蛋白的饲料和正常饲料后ALP1表达量的差异.[结果]ALP1在棉铃虫整个发育期都表达,幼虫的表达量最高,蛹期表达量最低,在成虫体内也有较高的表达;ALP1在幼虫中肠表达量最高,其次是后肠、前肠、马氏管,表皮中的表达量最低;与敏感品系相比,对Cry1Ac具有中等水平抗性的棉铃虫ALP1表达量明显增加,尤其是取食含Cry1Ac蛋白饲料的抗性棉铃虫幼虫的ALP1的表达量显著升高,但抗性棉铃虫取食正常饲料后,2、3龄幼虫的ALP1的表达量与敏感棉铃虫差异不显著;所有的抗性品系4龄棉铃虫幼虫中肠ALP1的表达量都显著高于敏感品系,而且随着棉铃虫抗性倍数的升高,ALP1的表达量呈逐渐降低的趋势.[结论]抗性棉铃虫中肠ALP1表达量的改变可能与Cry1Ac抗性、Cry1Ac代谢有一定的关系.%[Objective] The objective of this study is to provide a theoretical basis for further clarifying Cry1Ac resistance mechanism and constituting reasonable resistance management strategy,the difference of ALP1 expression level between Cry1Ac-resistant and susceptible Helicoverpa armigera,the effect of Cry1Ac toxin on ALP1 expression level in Cry1Ac-resistant larvae and the relationship between ALP 1 and Cry 1 Ac-resistant strains were analyzed.[Method] The expression levels of ALP1 in susceptible and Cry1Ac-resistant H.armigera larvae feeding on artificial diet containing Cry1Ac and no-Cry1Ac were compared using real-time quantitative PCR analysis.[Result] The ALP1 could express in whole development period ofH.armigera,the highest expression level

  19. Highly-Efficient and Modular Medium-Voltage Converters

    Science.gov (United States)

    2015-09-28

    4. TITLE AND SUBTITLE Highly-Efficient and Modula Medium -Voltage Converters 6. AUTHOR(S) Maryam Saeedifard 7. PERFORMING ORGANIZATIC i NAME(S...realization of highly efficient, modular medium - voltage dc-ac and dc-dc energy conversion systems by development of new control strategies that improve the...Z39.18 a 01^ 100(0^5 Final Report for Grant N00014-14-1-0615 Highly-Efficient and Modular Medium -Voltage Converters Lead Organization: Georgia Tech

  20. Isolation of sequences flanking Ac insertion sites by Ac casting.

    Science.gov (United States)

    Wang, Dafang; Peterson, Thomas

    2013-01-01

    Localizing Ac insertions is a fundamental task in studying Ac-induced mutation and chromosomal rearrangements involving Ac elements. Researchers may sometimes be faced with the situation in which the sequence flanking one side of an Ac/Ds element is known, but the other flank is unknown. Or, a researcher may have a small sequence surrounding the Ac/Ds insertion site and needs to obtain additional flanking genomic sequences. One way to rapidly clone unknown Ac/Ds flanking sequences is via a PCR-based method termed Ac casting. This approach utilizes the somatic transposition activity of Ac during plant development, and provides an efficient means for short-range genome walking. Here we describe the principle of Ac casting, and show how it can be applied to isolate Ac macrotransposon insertion sites.

  1. Flame spread over inclined electrical wires with AC electric fields

    KAUST Repository

    Lim, Seung J.

    2017-07-21

    Flame spread over polyethylene-insulated electrical wires was studied experimentally with applied alternating current (AC) by varying the inclination angle (θ), applied voltage (VAC), and frequency (fAC). For the baseline case with no electric field applied, the flame spread rate and the flame width of downwardly spreading flames (DSFs) decreased from the horizontal case for −20° ≤ θ < 0° and maintained near constant values for −90° ≤ θ < −20°, while the flame spread rate increased appreciably as the inclination angle of upwardly spreading flames (USFs) increased. When an AC electric field was applied, the behavior of flame spread rate in DSFs (USFs) could be classified into two (three) sub-regimes characterized by various functional dependences on VAC, fAC, and θ. In nearly all cases of DSFs, a globular molten polyethylene formed ahead of the spreading flame edge, occasionally dripping onto the ground. In these cases, an effective flame spread rate was defined to represent the burning rate by measuring the mass loss due to dripping. This effective spread rate was independent of AC frequency, while it decreased linearly with voltage and was independent of the inclination angle. In DSFs, when excessively high voltage and frequency were applied, the dripping led to flame extinction during propagation and the extinction frequency correlated well with applied voltage. In USFs, when high voltage and frequency were applied, multiple globular molten PEs formed at several locations, leading to ejections of multiple small flame segments from the main flame, thereby reducing the flame spread rate, which could be attributed to the electrospray phenomenon.

  2. Resistance Characteristics of Arc in Long Air Gap

    Institute of Scientific and Technical Information of China (English)

    YU Zhanqing; YU Junjie; ZENG Rong; CHEN He; PENG Xiang

    2013-01-01

    Arc resistance is an important parameter for characterizing long arcs in air,and its laboratory testing is of importance for accurate arc modeling of electromagnetic transient caused by short circuit fault.Therefore,we constructed an experimental system to study the characteristics of long AC arc in air.Driven by currents of 10 kA or 40 kA (root mean square value),the system produces arcs with different initial lengths of 1 m,2 m and 4 m,and the movement of the arcs are captured by a high-speed camera.After performing experiments using the system,we carried out analysis and comparisons of the arc resistance of arcs with different lengths and different currents,as well as a study of the relationship between the macro-morphology and the resistance of the arcs.Conclusions were drawn from the experimental results:the arc voltage had obvious saturation characteristics; the arc resistance increased with the increase of arc length and the decrease of current; the arcs bended or extended significantly in time and the peak arc voltage within a single cycle increased correspondingly; the arcs had voltage and current in the same phase.In the end,a formula of arc resistance based on the experiment results is derived.

  3. Push-pull with recovery stage high-voltage DC converter for PV solar generator

    Science.gov (United States)

    Nguyen, The Vinh; Aillerie, Michel; Petit, Pierre; Pham, Hong Thang; Vo, Thành Vinh

    2017-02-01

    A lot of systems are basically developed on DC-DC or DC-AC converters including electronic switches such as MOS or bipolar transistors. The limits of efficiency are quickly reached when high output voltages and high input currents are needed. This work presents a new high-efficiency-high-step-up based on push-pull DC-DC converter integrating recovery stages dedicated to smart HVDC distributed architecture in PV solar energy production systems. Appropriate duty cycle ratio assumes that the recovery stage work with parallel charge and discharge to achieve high step-up voltage gain. Besides, the voltage stress on the main switch is reduced with a passive clamp circuit and thus, low on-state resistance Rdson of the main switch can be adopted to reduce conduction losses. Thus, the efficiency of a basic DC-HVDC converter dedicated to renewable energy production can be further improved with such topology. A prototype converter is developed, and experimentally tested for validation.

  4. Lightning-induced overvoltages in medium voltage distribution systems and customer experienced voltage spikes

    Energy Technology Data Exchange (ETDEWEB)

    Sabiha, N. A.

    2010-07-01

    In Finland, distribution transformers are frequently subjected to lightning strokes for which they are continuously protected by spark-gaps. So, the breakdown probability of medium voltage (MV) spark-gaps is modeled using the Gaussian distribution function under an impulse voltage test in accordance with the IEC 60060-1 standard. The model is presented in the form of the well-known Gaussian tail probability. Accordingly, a modified probabilistic model is proposed to study the effect of impulse voltage superimposed on the ac voltage on the breakdown probability of MV spark-gaps. The modified model is verified using experimental data, where the experimental setup is arranged to generate a range of impulse voltages superimposed on the ac voltages. The experimental verification shows evidence of the efficacy of the proposed probabilistic model. Furthermore, the proposed model is used to evaluate single-phase, two-phase and three-phase spark-gap breakdown probabilities in the case of lightning induced overvoltages. These breakdown probabilities are used along with the simplified Rusck expression to evaluate the performance of MV overhead lines above a perfectly conducting ground under lightning-induced overvoltages using a statistical approach. In order to study the overvoltages propagating through the transformer to its low voltage side, the high frequency model of the transformer is investigated. First, the investigation is carried out using model introduced by Piantini at no-load condition. This model is modified to take more than one resonance frequency into consideration. Therefore, the frequency response of the simulated transient voltage is improved. A verification of the modified model is carried out through the comparison between the experimental and simulation results, in which the time domain simulation is carried out using ATP/EMTP while MATLAB is used to identify the model parameters. As this model is found suitable only for unloaded transformer, an

  5. Voltage margin control for offshore multi-use platform integration

    DEFF Research Database (Denmark)

    Mier, V.; Casielles, P.G.; Koto, J.

    terminal VSC-MTDC which includes offshore generation, storage, loads and ac connection, was modeled and simulated in DigSILENT Power Factory software. Voltage margin method has been used for reliable operation of the MTDC system without the need of fast communication. Simulation results show...

  6. Measurements for validation of high voltage underground cable modelling

    DEFF Research Database (Denmark)

    Bak, Claus Leth; Gudmundsdottir, Unnur Stella; Wiechowski, Wojciech Tomasz

    2009-01-01

    This paper discusses studies concerning cable modelling for long high voltage AC cable lines. In investigating the possibilities of using long cables instead of overhead lines, the simulation results must be trustworthy. Therefore a model validation is of great importance. This paper describes...

  7. MODIFICATIONS OF DIODE RECTIFIER CIRCUITS FOR CONTINUOUS INSULATION MEASUREMENT IN LIVE AC IT NETWORKS

    Directory of Open Access Journals (Sweden)

    Piotr Olszowiec

    2016-05-01

    Full Text Available Purpose. In the paper there are described few systems of insulation resistance continuous measurement using an imposed DC test signal delivered by diode rectifiers. Drawbacks of this technique are pointed out and ways of these shortcomings removal are proposed. Methodology. An improved version of measuring circuit based on a single-phase diode rectifier is presented. Application of logometric measuring devices is suggested. Results. A new insulation resistance continuous measuring system is insensitive to network voltages variation and asymmetry. Modified circuit enables also implementation of a simple device for alarming the monitored network’s insulation deterioration and/or earth-fault protection. Originality. Formulas describing performance of diode rectifiers under asymmetrical supply have not been available so far. Both innovations (i.e. single-phase diode rectifier and logometric meter have not been applied widely for implementation of continuous insulation monitoring in live AC IT networks. Practical value. Use of both innovations will allow to eliminate unrequired dependence of measurement results on variable network voltages as well as their possible asymmetry. Exploitation of diode rectifier circuits for earth fault location is also possible.

  8. 30 CFR 75.902 - Low- and medium-voltage ground check monitor circuits.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Low- and medium-voltage ground check monitor... Medium-Voltage Alternating Current Circuits § 75.902 Low- and medium-voltage ground check monitor circuits. On or before September 30, 1970, low- and medium-voltage resistance grounded systems shall...

  9. A New Secondary Control Approach for Voltage Regulation in DC Microgrids

    DEFF Research Database (Denmark)

    Peyghami Akhuleh, Saeed; Mokhtari, Hossein; Davari, Pooya;

    2016-01-01

    feeders with much voltage drop on the line resistances, the conventional methods may not guarantee the voltage regulation on the load busses. Therefore, in addition to compensate the voltage drop of the primary controller, it is necessary to regulate the voltage of critical loads. In this paper, a new...

  10. 30 CFR 77.804 - High-voltage trailing cables; minimum design requirements.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false High-voltage trailing cables; minimum design... OF UNDERGROUND COAL MINES Surface High-Voltage Distribution § 77.804 High-voltage trailing cables; minimum design requirements. (a) High-voltage trailing cables used in resistance grounded systems shall...

  11. Determination of the aging offset voltage of AMR sensors based on accelerated degradation test

    NARCIS (Netherlands)

    Zambrano, Andreina; Kerkhoff, Hans G.

    2015-01-01

    Usually Anisotropic Magnetoresistance angle sensors are configured with two Wheatstone bridges, but an undesirable offset voltage included in the sensor output affects its accuracy. The total offset voltage combines a voltage due to resistance mismatches during manufacturing and a voltage from inequ

  12. Analysis of Physics Processes in the AC Plasma Torch Discharge under High Pressure

    Science.gov (United States)

    Safronov, A. A.; Vasilieva, O. B.; Dudnik, J. D.; E Kuznetsov, V.; Kuchina, J. A.; Shiryaev, V. N.; Pavlov, A. V.

    2017-04-01

    The paper is devoted to investigation of electrophysical processes in the electric discharge generated by a three-phase AC plasma torch when using a high pressure inert working gas. AC plasma torch design with end electrodes intended for work on inert gases at pressures up to 81 bar is studied. Current-voltage characteristics for different gas flow rates and pressures are presented. Physical processes characteristics of the arising voltage ripples which depend on various working parameters of the plasma torch have been investigated. Arc burning processes in the electric discharge chamber of the three-phase AC plasma torch at various working parameters were photographed.

  13. Surge currents and voltages at the low voltage power mains during lightning strike to a GSM tower

    Energy Technology Data Exchange (ETDEWEB)

    Markowska, Renata [Bialystok Technical University (Poland)], E-mail: remark@pb.edu.pl

    2007-07-01

    The paper presents the results of numerical calculations of lightning surge currents and voltages in the low voltage power mains system connected to a free standing GSM base station. Direct lightning strike to GSM tower was studied. The analysis concerned the current that flows to the transformer station through AC power mains, the potential difference between the grounding systems of the GSM and the transformer stations and the voltage differences between phase and PE conductors of the power mains underground cable at both the GSM and the transformer sides. The calculations were performed using a numerical program based on the electromagnetic field theory and the method of moments. (author)

  14. Technological Aspects: High Voltage

    CERN Document Server

    Faircloth, D C

    2013-01-01

    This paper covers the theory and technological aspects of high-voltage design for ion sources. Electric field strengths are critical to understanding high-voltage breakdown. The equations governing electric fields and the techniques to solve them are discussed. The fundamental physics of high-voltage breakdown and electrical discharges are outlined. Different types of electrical discharges are catalogued and their behaviour in environments ranging from air to vacuum are detailed. The importance of surfaces is discussed. The principles of designing electrodes and insulators are introduced. The use of high-voltage platforms and their relation to system design are discussed. The use of commercially available high-voltage technology such as connectors, feedthroughs and cables are considered. Different power supply technologies and their procurement are briefly outlined. High-voltage safety, electric shocks and system design rules are covered.

  15. Distributed Control to Ensure Proportional Load Sharing and Improve Voltage Regulation in Low-Voltage DC Microgrids

    DEFF Research Database (Denmark)

    Anand, Sandeep; G. Fernandes, Baylon; Guerrero, Josep M.

    2013-01-01

    DC microgrids are gaining popularity due to high efficiency, high reliability, and easy interconnection of renewable sources as compared to the ac system. Control objectives of dc microgrid are: 1) to ensure equal load sharing (in per unit) among sources; and 2) to maintain low-voltage regulation...

  16. Investigation of Transformer Winding Architectures for High Voltage Capacitor Charging Applications

    DEFF Research Database (Denmark)

    Schneider, Henrik; Thummala, Prasanth; Huang, Lina

    2014-01-01

    Transformer parameters such as leakage inductance and self-capacitance are rarely calculated in advance during the design phase, because of the complexity and huge analytical error margins caused by practical winding implementation issues. Thus, choosing one transformer architecture over another...... for a given design is usually based on experience or a trial and error approach. This work presents equations regarding calculation of leakage inductance, self-capacitance and AC resistance in transformer winding architectures, ranging from the common non-interleaved primary/secondary winding architecture......, to an interleaved, sectionalized and bank winded architecture. The analytical results are evaluated experimentally and through FEM simulations. Different transformer winding architectures are investigated in terms of the losses caused by the transformer parasitics for a bidirectional high-voltage (~1500 V) flyback...

  17. General analytical solutions for DC/AC circuit network analysis

    CERN Document Server

    Rubido, Nicolás; Baptista, Murilo S

    2014-01-01

    In this work, we present novel general analytical solutions for the currents that are developed in the edges of network-like circuits when some nodes of the network act as sources/sinks of DC or AC current. We assume that Ohm's law is valid at every edge and that charge at every node is conserved (with the exception of the source/sink nodes). The resistive, capacitive, and/or inductive properties of the lines in the circuit define a complex network structure with given impedances for each edge. Our solution for the currents at each edge is derived in terms of the eigenvalues and eigenvectors of the Laplacian matrix of the network defined from the impedances. This derivation also allows us to compute the equivalent impedance between any two nodes of the circuit and relate it to currents in a closed circuit which has a single voltage generator instead of many input/output source/sink nodes. Contrary to solving Kirchhoff's equations, our derivation allows to easily calculate the redistribution of currents that o...

  18. High voltage engineering

    CERN Document Server

    Rizk, Farouk AM

    2014-01-01

    Inspired by a new revival of worldwide interest in extra-high-voltage (EHV) and ultra-high-voltage (UHV) transmission, High Voltage Engineering merges the latest research with the extensive experience of the best in the field to deliver a comprehensive treatment of electrical insulation systems for the next generation of utility engineers and electric power professionals. The book offers extensive coverage of the physical basis of high-voltage engineering, from insulation stress and strength to lightning attachment and protection and beyond. Presenting information critical to the design, selec

  19. High voltage test techniques

    CERN Document Server

    Kind, Dieter

    2001-01-01

    The second edition of High Voltage Test Techniques has been completely revised. The present revision takes into account the latest international developments in High Voltage and Measurement technology, making it an essential reference for engineers in the testing field.High Voltage Technology belongs to the traditional area of Electrical Engineering. However, this is not to say that the area has stood still. New insulating materials, computing methods and voltage levels repeatedly pose new problems or open up methods of solution; electromagnetic compatibility (EMC) or components and systems al

  20. Fabrication of alumina films with laminated structures by ac anodization

    Directory of Open Access Journals (Sweden)

    Hiroyo Segawa

    2014-01-01

    Full Text Available Anodization techniques by alternating current (ac are introduced in this review. By using ac anodization, laminated alumina films are fabricated. Different types of alumina films consisting of 50–200 nm layers were obtained by varying both the ac power supply and the electrolyte. The total film thickness increased with an increase in the total charge transferred. The thickness of the individual layers increased with the ac voltage; however, the anodization time had little effect on the film thickness. The laminated alumina films resembled the nacre structure of shells, and the different morphologies exhibited by bivalves and spiral shells could be replicated by controlling the rate of increase of the applied potentials.

  1. Mitigation of Unbalanced Voltage Sags and Voltage Unbalance in CIGRE Low Voltage Distribution Network

    OpenAIRE

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Mahat, Pukar; Cecati, Carlo

    2013-01-01

    Any problem with voltage in a power network is undesirable as it aggravates the quality of the power. Power electronic devices such as Voltage Source Converter (VSC) based Static Synchronous Compensator (STATCOM) etc. can be used to mitigate the voltage problems in the distribution system. The voltage problems dealt with in this paper are to show how to mitigate unbalanced voltage sags and voltage unbalance in the CIGRE Low Voltage (LV) test network and net-works like this. The voltage unbala...

  2. Impedance of goat eye lens at different DC voltages.

    Science.gov (United States)

    Kohli, K S; Rai, D V; Jindal, V K; Goyal, N

    1998-09-01

    A computer assisted AC impedance system is used to measure the DC voltage-current (V-I) characteristics and AC impedance of a goat eye lens using a two-probe Ag-AgCl electrode system. The measurement of the V-I characteristics shows that when a DC voltage from 0 mV to 30 mV is applied, the resultant current decreases from an initial value of 0.58 microA to 0.006 microA. However, when the voltage is increases beyond 30 mV, the current increases and reaches a value of 0.9 microA at 100 mV. The data on the frequency response (0.01-10 Hz) of the impedance of lens tissue show an inverse relationship with frequency. The effect of various DC voltages, namely 0, 30, 50, 100 and 200 mV, on the impedance of the eye lens is also investigated over a frequency range of 0.01-10 Hz. The measurement results for both V-I characteristics and AC impedance further suggest the presence of a 30 mV voltage compartment in the goat eye lens.

  3. AC Versus DC Link Comparison Based on Power Flow Analysis of a Multimachine Power System

    OpenAIRE

    Mohammed Abdeljalil DJEHAF; Sid Ahmed ZIDI; Youcef DJILANI KOBIBI

    2014-01-01

    Deregulation and privatization is posing new challenges on high voltage transmission and on distributions systems as well. An increasingly liberalized market will encourage trading opportunities to be identified and developed. High voltage power electronics, such as HVDC (High Voltage Direct Current) and FACTS (Flexible AC Transmission Systems) provide the necessary features to avoid technical problems in heavily loaded power systems; HVDC offers most advantages: it can be used for system int...

  4. AC stabilities in superconducting magnetic shielding body with shorted low AC loss Nb{sub 3}Sn coil; Nb{sub 3}Sn kansen jiki shaheitai no koryu anteisei

    Energy Technology Data Exchange (ETDEWEB)

    Aizawa, N.; Nii, A.; Ito, Y.; Onishi, T. [Hokkaido Univ., Hokkaido (Japan); Shibuya, M. [Engineering Research Association for Superconductive Genertion Equipment and Materials, Osaka (Japan)

    1999-06-07

    In this study, the superconducting magnetic shielding body conductively cooled by the small refrigerating machine at the intermediate temperature (10K-14K) was examined with the aim of a magnetic shielding type superconducting current limiter as closed as maintenance-free. Nb{sub 3}Sn coil closed the two ends was an object as a magnetic shielding body. In case of such a cooling system, the research of the stability was indispensable because of possible normal conduction transition in addition of disturbance into tapes. Then, the method to use the thyristor bypass circuit was examined in order to establish the stabilization method. As for the simulation, the normal conduction transition of the low AC loss Nb{sub 3}Sn coil which AC transferred in the constant-voltage power source, and the recovery characteristics of superconductivity were analyzed in the liquid helium. As a result of evaluating the stability in the constant-voltage power source, it was shown that the current attenuated by the resistance, and the exothermic reaction was controlled even if the disturbance happened and quenched. From these results, it was clarified that the stabilization method to establish the thyristor bypass circuit was effective for improvement on the stability of the superconductor. (NEDO)

  5. Inductor Compensation in Three Phase PFC Control with Decoupling the Input Voltage and Bus Voltage

    Directory of Open Access Journals (Sweden)

    Luo Guang

    2016-01-01

    Full Text Available As the nonlinear structure of the boost ac/dc topology, the PFC is difficult to be controlled. The average state space theory has revealed that the choke current is determined by duty-ratio coupled with input voltage and bus voltage, which makes the high-performance sine-wave current track control more challenging. To remove disturbing variables and reduce the zero-crossing distortion, the decoupling control strategy is presented. Also, it is shown in this paper that the variable inductance has a great influence on PFC and THDI. As the inductor in boost converter varies with the current, a compensating coefficient of current is also proposed. The decoupling strategy and the inductor compensation strategy are implemented on a UPS with three phase input voltage. Numerical simulation and experimental results has indicated the high-performance of these control strategy.

  6. Power conditioning for low-voltage piezoelectric stack energy harvesters

    Science.gov (United States)

    Skow, E.; Leadenham, S.; Cunefare, K. A.; Erturk, A.

    2016-04-01

    Low-power vibration and acoustic energy harvesting scenarios typically require a storage component to be charged to enable wireless sensor networks, which necessitates power conditioning of the AC output. Piezoelectric beam-type bending mode energy harvesters or other devices that operate using a piezoelectric element at resonance produce high voltage levels, for which AC-DC converters and step-down DC-DC converters have been previously investigated. However, for piezoelectric stack energy harvesters operating off-resonance and producing low voltage outputs, a step-up circuit is required for power conditioning, such as seen in electromagnetic vibration energy scavengers, RF communications, and MEMS harvesters. This paper theoretically and experimentally investigates power conditioning of a low-voltage piezoelectric stack energy harvester.

  7. AC Losses of Prototype HTS Transmission Cables

    Energy Technology Data Exchange (ETDEWEB)

    Demko, J.A.; Dresner, L.; Hughey, R.L.; Lue, J.W.; Olsen, S.K.; Sinha, U.; Tolbert, J.C.

    1998-09-13

    Since 1995 Southwire Company and Oak Ridge National Laboratory (ORNL) have jointly designed, built, and tested nine, l-m long, high temperature superconducting (HTS) transmission cable prototypes. This paper summarizes the AC loss measurements of five of the cables not reported elsewhere, and compares the losses with each other and with theory developed by Dresner. Losses were measured with both a calorimetric and an electrical technique. Because of the broad resistive transition of the HTS tapes, the cables can be operated stably beyond their critical currents. The AC losses were measured in this region as well as below critical currents. Dresner's theory takes into account the broad resistive transition of the HTS tapes and calculates the AC losses both below and above the critical current. The two sets of AC 10SS data agree with each other and with the theory quite welL In particular, at low currents of incomplete penetration, the loss data agree with the theoretical prediction of hysteresis loss based on only the outer two Iayers carrying the total current.

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

    Science.gov (United States)

    Liu, Jianxing; Laghrouche, Salah; Wack, Maxime

    2014-06-01

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

  9. Pulse, dc and ac breakdown in high pressure gas discharge lamps

    Science.gov (United States)

    Beckers, J.; Manders, F.; Aben, P. C. H.; Stoffels, W. W.; Haverlag, M.

    2008-07-01

    An optical study of pulse, dc, and ac (50-400 kHz) ignition of metal halide lamps has been performed by investigating intensified CCD camera images of the discharges. The ceramic lamp burners were filled with xenon gas at pressures of 300 and 700 mbar. In comparison with dc and pulse ignition, igniting with an ac voltage decreases the ignition voltage by up to 56% and the breakdown time scales get much longer (~10-3 s compared with ~10-7 s for pulse ignition). Increasing the ac frequency decreases the ignition voltages and changes the ionization channel shapes. External irradiation of UV light can have either an increasing or a decreasing effect on ignition voltages.

  10. High-frequency power supply for making electro-resistance-welded tubes. Denhokanyo koshuha dengen

    Energy Technology Data Exchange (ETDEWEB)

    Konno, M. (Meidensha Corp., Tokyo (Japan))

    1991-12-27

    This paper introduces the current status of the Meidensha Corporation mainly on parts of a large-capacity electron-tube type high-frequency power supply for making electro-resistance-weld tubes (RFG). The company produces RFGs with oscillation output ranging from 65 to 1300 kW. The company uses oscillation tubes made by Nippon Electric Company for an oscillation output of 400 kW or lower, and those made by Siemens for above 400 kW. A water-cooled cylindrical capacitor, which has a unit capacity about five times as much of a disk type porcelain capacitor, enables constructing a compact tank circuit. The output from the oscillator driving power supply is adjusted by a thyristor AC control on the primary side of a positive transformer. The positive transformer (TF) adopts water cooling type for 100 kW or lower, and oil-filled self-cooling type for above 100 kW. The DC high-voltage power supply uses the power of the primary side of the positive TF which is controlled by a thyrisctor AC controller, and subjected to a three-face full-wave rectification using high-voltage silicon diodes. The oscillation tube, which operates on thermal electrons is heated to a prescribed temperature, of which value is controlled by the cathode heating power supply voltage. The voltage adjustment uses a constant voltage transformers system. 1 fig., 2 tabs.

  11. AC-3 audio coder

    Science.gov (United States)

    Todd, Craig

    1995-12-01

    AC-3 is a system for coding up to 5.1 channels of audio into a low bit-rate data stream. High quality may be obtained with compression ratios approaching 12-1 for multichannel audio programs. The high compression ratio is achieved by methods which do not increase decoder memory, and thus cost. The methods employed include: the transmission of a high frequency resolution spectral envelope; and a novel forward/backward adaptive bit allocation algorithm. In order to satisfy practical requirements of an emissions coder, the AC-3 syntax includes a number of features useful to broadcasters and consumers. These features include: loudness uniformity between programs; dynamic range control; and broadcaster control of downmix coefficients. The AC-3 coder has been formally selected for inclusion of the U.S. HDTV broadcast standard, and has been informally selected for several additional applications.

  12. Tevatron AC dipole system

    Energy Technology Data Exchange (ETDEWEB)

    Miyamoto, R.; Kopp, S.E.; /Texas U.; Jansson, A.; Syphers, M.J.; /Fermilab

    2007-06-01

    The AC dipole is an oscillating dipole magnet which can induce large amplitude oscillations without the emittance growth and decoherence. These properties make it a good tool to measure optics of a hadron synchrotron. The vertical AC dipole for the Tevatron is powered by an inexpensive high power audio amplifier since its operating frequency is approximately 20 kHz. The magnet is incorporated into a parallel resonant system to maximize the current. The use of a vertical pinger magnet which has been installed in the Tevatron made the cost relatively inexpensive. Recently, the initial system was upgraded with a more powerful amplifier and oscillation amplitudes up to 2-3{sigma} were achieved with the 980 GeV proton beam. This paper discusses details of the Tevatron AC dipole system and also shows its test results.

  13. Combined Digital Electronic Current and Voltage Transducer

    Institute of Scientific and Technical Information of China (English)

    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.

  14. Voltage verification unit

    Science.gov (United States)

    Martin, Edward J.

    2008-01-15

    A voltage verification unit and method for determining the absence of potentially dangerous potentials within a power supply enclosure without Mode 2 work is disclosed. With this device and method, a qualified worker, following a relatively simple protocol that involves a function test (hot, cold, hot) of the voltage verification unit before Lock Out/Tag Out and, and once the Lock Out/Tag Out is completed, testing or "trying" by simply reading a display on the voltage verification unit can be accomplished without exposure of the operator to the interior of the voltage supply enclosure. According to a preferred embodiment, the voltage verification unit includes test leads to allow diagnostics with other meters, without the necessity of accessing potentially dangerous bus bars or the like.

  15. MPPT algorithm for voltage controlled PV inverters

    DEFF Research Database (Denmark)

    Kerekes, Tamas; Teodorescu, Remus; Liserre, Marco;

    2008-01-01

    This paper presents a novel concept for an MPPT that can be used in case of a voltage controlled grid connected PV inverters. In case of single-phase systems, the 100 Hz ripple in the AC power is also present on the DC side. Depending on the DC link capacitor, this power fluctuation can be used t...... to track the MPP of the PV array, using the information that at MPP the power oscillations are very small. In this way the algorithm can detect the fact that the current working point is at the MPP, for the current atmospheric conditions....

  16. Local Dynamic Reactive Power for Correction of System Voltage Problems

    Energy Technology Data Exchange (ETDEWEB)

    Kueck, John D [ORNL; Rizy, D Tom [ORNL; Li, Fangxing [ORNL; Xu, Yan [ORNL; Li, Huijuan [University of Tennessee, Knoxville (UTK); Adhikari, Sarina [ORNL; Irminger, Philip [ORNL

    2008-12-01

    Distribution systems are experiencing outages due to a phenomenon known as local voltage collapse. Local voltage collapse is occurring in part because modern air conditioner compressor motors are much more susceptible to stalling during a voltage dip than older motors. These motors can stall in less than 3 cycles (.05s) when a fault, such as on the sub-transmission system, causes voltage to sag to 70 to 60%. The reasons for this susceptibility are discussed in the report. During the local voltage collapse, voltages are depressed for a period of perhaps one or two minutes. There is a concern that these local events are interacting together over larger areas and may present a challenge to system reliability. An effective method of preventing local voltage collapse is the use of voltage regulation from Distributed Energy Resources (DER) that can supply or absorb reactive power. DER, when properly controlled, can provide a rapid correction to voltage dips and prevent motor stall. This report discusses the phenomenon and causes of local voltage collapse as well as the control methodology we have developed to counter voltage sag. The problem is growing because of the use of low inertia, high efficiency air conditioner (A/C) compressor motors and because the use of electric A/C is growing in use and becoming a larger percentage of system load. A method for local dynamic voltage regulation is discussed which uses reactive power injection or absorption from local DER. This method is independent, rapid, and will not interfere with conventional utility system voltage control. The results of simulations of this method are provided. The method has also been tested at the ORNL s Distributed Energy Communications and Control (DECC) Laboratory using our research inverter and synchronous condenser. These systems at the DECC Lab are interconnected to an actual distribution system, the ORNL distribution system, which is fed from TVA s 161kV sub-transmission backbone. The test results

  17. Control Strategy for Three Phase Voltage Source PWM Rectifier Based on the Space Vector Modulation

    Directory of Open Access Journals (Sweden)

    MILOUD, Y.

    2010-08-01

    Full Text Available This paper proposes the space vector pulse width modulation (SVPWM control scheme for three-phase voltage source PWM rectifier. The control system based on SVPWM includes two PI controllers which are used to regulate the AC currents and DC-link voltage. The proposed control can stabilize the minimum of the systems storage function at the desired equilibrium point determined by unity power factor and sinusoidal current on the AC side, and constant output voltage on the DC side. So the stable state performance and robustness against the load�s disturbance of PWM rectifiers are both improved. The simulation result shows feasibility of this strategy.

  18. Four-Switch Three-Phase PMSM Converter with Output Voltage Balance and DC-Link Voltage Offset Suppression

    Directory of Open Access Journals (Sweden)

    Fadil Hicham

    2017-01-01

    Full Text Available High power quality, efficiency, complexity, size, cost effectiveness and switching losses of the direct current to alternating current (DC–AC conversion system are crucial aspects in industrial applications. Therefore, the four-switch three-phase inverter (4S3P has been proposed as an innovative inverter design. However, this topology has been known to have many performance limitations in the low-frequency region, because of the generation of an unbalanced voltage leading to an unbalanced current due to the fluctuation and offset of the centre tap voltage of the DC-link capacitors. Those drawbacks are investigated and solved in this paper in order to provide pure sinusoidal output voltages. The generated output voltages are controlled using proportional-integral (PI controllers to follow the desired voltages. Furthermore, the DC-link capacitor voltage offset is mitigated by subtracting the direct component from the control reference voltage using low pass filters, where this direct voltage component provides the direct current component which leads to DC-link capacitor voltage divergence. A simulation model and experimental setup are used to validate the proposed concept. Many simulation and experimental results are carried out to show the effectiveness of the proposed control scheme.

  19. Introducing AC Inductive Reactance with a Power Tool

    Science.gov (United States)

    Bryant, Wesley; Baker, Blane

    2016-01-01

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

  20. An Optoelectronic High-voltage Probe for Measuring Impulse Voltage Distribution of HVDC Converter Valve

    Institute of Scientific and Technical Information of China (English)

    方志; 邱毓昌

    2007-01-01

    A high-voltage optoelectronic probe is developed for measuring impulse voltage distribution along thyristor units in the HVDC converter valve. The dimension of the resistive voltage divider is optimized by means of numerical compttation of electric field. A pulse frequency modulation (PFM) mode is adopted for the data transmission link because of its immunity to high-intensity electromagnetic interference. Experimental results indicate that the linearity deviation for the whole measuring system is within ± 0.15 %, and therefore it can meet requirements specified by IEC60700-1.

  1. 压电发电机AC-DC输出性能的优化与仿真研究%The Optimization and Simulation of the AC-DC Output Performances of Piezoelectric Generator

    Institute of Scientific and Technical Information of China (English)

    金文平; 王光庆; 展永政

    2014-01-01

    The AC-DC transferring circuit greatly affects the output performances of the piezoelectric vibration generator (PVG).In order to improve the output performance and the energy conversion efficiency of the PVG,this paper presents the equivalent circuit model of the PVG at first,and then the analytical expressions of the AC-DC cir-cuit,such as the output voltage and the output power,are derived by using the mechanical equilibrium principle and circuit theory when the PVG operates under the steady-state.To maximize the output power of the AC-DC transfer-ring circuit,the optimization of the output power with different resistance loads are carried out by using differential calculation method,and the optimal load resistance,displacement,output voltage and output power are obtained un-der the open-circuit resonance and short-circuits resonance condition respectively.Some simulations are carried out to analyze the output performances of the PVG.The validity are performed by compared the results with the coupling a-nalysis results of Ottman and the in-phase analysis results of Guyomar.The results have shown that the optimization of the output performance of the AC-DC circuit is attributing to enhance the total performance and the energy con-version efficiency of the PVG.%交流-直流(AC-DC)转换电路对压电振动发电机的输出性能影响较大,为提高压电发电机 AC-DC转换电路的输出性能和能量转换效率,该文首先给出了压电振动发电机系统等效电路模型,基于该模型利用力学平衡原理和电路理论推导了发电机稳态运行时 AC-DC输出电压和输出功率表达式。以输出功率最大化为优化目标,通过微分计算对发电机 AC-DC转换电路在不同负载电阻下的输出功率进行了优化分析,分别得到了发电机在开路谐振和短路谐振状态下优化的负载电阻、振动位移、输出电压和输出功率。仿真与对比分析了发电机优化后的输出

  2. Appropriate green phosphor of SrSi2O2N2:Eu2+,Mn2+ for AC LEDs.

    Science.gov (United States)

    Yeh, Chiao-Wen; Li, Ye; Wang, Jing; Liu, Ru-Shi

    2012-07-30

    An AC (alternating current) LED exhibited the advantages of a low drive current, low static electricity, lack of a need for a rectifier, and high extraction efficiency. The input operating voltage of an AC LED is around 80V, and its operating frequency is 120 Hz or less. When the voltage is converted, a time gap of 1/120 s (10 ms), called dead time, is generated. This time gap is closely related to the scintillation phenomenon. Therefore, AC LEDs that have a phosphor composition, whose half-life composition can compensate for dead time that is generated during the voltage conversion, are sought to solve the problem of scintillation. The object of this work is to provide a phosphor SrSi(2)O(2)N(2):Eu(2+),Mn(2+) for AC LEDs, in which the dead time that is generated during the voltage conversion is compensated for by the half-life of the phosphor.

  3. Application of Distribution Power Electronic Transformer for Medium Voltage

    Directory of Open Access Journals (Sweden)

    Prashant Kumar

    2014-12-01

    Full Text Available In   this   paper   a   distribution   power electronic transformer (DPET for feeding critical loads is presented. The PE based transformer is a multi-port converter that can connect to medium voltage levels on the primary side. Bidirectional power flow is provided to the each module. The presented structure consists of three stages: an input stage, an isolation stage, and an output stage.  The input current is sinusoidal, and it converts the high AC input voltage to low DC voltages. The isolated DC/DC converters are then connected to the DC links and provide galvanic isolation between the HV and LV sides. Finally, a three-phase inverter generates the AC output with the desired amplitude and frequency. The proposed DPET is extremely modular and can be extended for different voltage and power levels. It performs typical functions and has advantages such as power factor correction, elimination of voltage sag and swell, and reduction of voltage flicker in load side. Also in comparison to conventional transformers, it has lower weight, lower volume and eliminates necessity for toxic dielectric coolants the DPET performance is verified in MATLAB simulation.

  4. Generic inertia emulation controller for multi-terminal voltage-source-converter high voltage direct current systems

    DEFF Research Database (Denmark)

    Zhu, Jiebei; Guerrero, Josep M.; Hung, William;

    2014-01-01

    within a safe and pre-defined range. A theoretical treatment of the INEC algorithm and its implementation and integration within a conventional VSC control system are presented, and the impact on the total DC capacitance required within the MTDC network to ensure that DC voltages vary within...... an acceptable range are discussed. The proposed INEC scheme is validated using a Matlab/Simulink model under various changes in demand and in response to AC network faults. The model incorporates a multi-machine AC power system connected to a MTDC transmission system with multiple converter-interfaced nodes....... The effectiveness of the INEC in damping post-fault oscillations and in enhancing AC system frequency stability is also investigated. The system is shown to perform well and is attractive for providing a stable MTDC system that is capable of providing valuable support to the connected AC systems....

  5. Frequency and voltage dependence of electric and dielectric properties of Au/TiO2/n-4H-SiC (metal-insulator-semiconductor) type Schottky barrier diodes

    Science.gov (United States)

    Tanrıkulu, E. E.; Yıldız, D. E.; Günen, A.; Altındal, Ş.

    2015-09-01

    The main electrical and dielectric properties of Au/TiO2/n-4H-SiC (MIS) type Schottky barrier diodes (SBDs) have been investigated as functions of frequency and applied bias voltage. We believe that the use of high dielectric interfacial layer between metal and semiconductor can improve the performance of Schottky diodes. From the experimental data, both electrical and dielectric parameters were found as strong function of frequency and applied bias voltage. The Fermi energy level (EF), the concentration of doping donor atoms (P), barrier height (ΦB) and series resistance (Rs) values were obtained from reverse and forward bias C-V characteristics. The changes in EF and ND with frequency are considerably low. Therefore, their values were taken at about constant. The real and imaginary parts of dielectric constant (\\varepsilon \\prime , \\varepsilon \\prime\\prime ), tangent loss (tanδ), ac electrical conductivity (σac), and real and imaginary parts of electric modulus (M‧ and M″) values were also obtained from reverse and forward bias C-V and G/ω-V characteristics. In addition, the voltage dependent profiles of all these electrical and dielectric parameters were drawn for each frequency. These results confirmed that both electrical and dielectric properties of Au/TiO2/n-4H-SiC (MIS) type SBD are quite sensitive to both the frequency and applied bias voltage due to surface polarization, density distribution of interface traps (Dit), and interfacial layer.

  6. DC-bus voltage control of grid-connected voltage source converter by using space vector modulated direct power control under unbalanced network conditions

    DEFF Research Database (Denmark)

    Xiao, Lei; Huang, Shoudao; Lu, Kaiyuan

    2013-01-01

    Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load. In this......Unbalanced grid voltage will cause large dc-bus voltage ripple and introduce high harmonic current components on the grid side. This will severely threaten the safety of the grid-connected voltage source converter (VSC) and consequently, affect the healthy operation condition of the load....... In this study, a new proportional-integral-resonant (PI-RES) controller-based, space vector modulated direct power control topology is proposed to suppress the dc-bus voltage ripple and in the same time, controlling effectively the instantaneous power of the VSC. A special ac reactive power reference component...

  7. A novel method to measure the generated voltage of a ZnO nanogenerator

    Energy Technology Data Exchange (ETDEWEB)

    Heever, Stanley T van den; Buettner, Ulrich; Perold, Willem J, E-mail: tsvdh@sun.ac.za [Department of Electrical and Electronic Engineering, Stellenbosch University, Cnr Banghoek Road and Joubert Street, 7600, Stellenbosch (South Africa)

    2011-09-30

    A novel method to measure the output voltage of a zinc oxide nanowire nanogenerator is proposed. Various tests are performed to verify that the output voltage does indeed originate from the nanogenerator and not from environmental noise. Although noise does influence the output voltage measurements, the output voltage is easily distinguishable from the measured noise. It is also shown that the method can be used to determine the internal resistance of the nanogenerator by measuring the output voltage over different output resistors.

  8. Assessment on the influence of resistive superconducting fault current limiter in VSC-HVDC system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Park, Byung-Bae; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2014-09-15

    Highlights: • The role of SFCLs in VSC-HVDC systems was evaluated. • Simulation model based on Korea Jeju-Haenam HVDC power system was designed. • An effect and the feasible locations of resistive SFCLs were evaluated. • DC line-to-line, DC line-to-ground and 3 phase AC faults were imposed and analyzed. - Abstract: Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results.

  9. Alternating current(AC) corrosion analyzed by electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ha, Tae Hyun; Kim, Dae Kyeong; Bae, Jeong Hyo; Lee, Hyun Goo; Lee, Sung Jin [Korea Electrotechnology Research Institute, Changwon (Korea, Republic of)

    2002-12-15

    So far, many research results on AC corrosion have been reported but each one is not consistent with another. In order to understand the characteristics and factors affecting on AC corrosion, Electrochemical impedance spectroscopy (E.I.S) was used and changes in kinetics and surface properties was analyzed. Generally, E.I.S. test has been used mainly for the diagnosis of the concrete corrosion and coating material. However, considering the outstanding functions of E.I.S. test, it can be adopted as a good method to study AC corrosion. Electrolyte resistance (R{sub sol}), double layer capacitance (C{sub dl}) and polarization resistance (R{sub p}) are the basic circuit elements. Using the model which is consist of these basic elements, various results of E.I.S. test can be interpreted. And through this method the mechanism and characteristics of AC corrosion can be explained

  10. P Voltage Control of DFIG with Two-Mass-Shaft Turbine Model Under Utility Voltage Disturbance

    Directory of Open Access Journals (Sweden)

    Hengameh Kojooyan Jafari

    2016-06-01

    Full Text Available Doubly fed induction generators as a variable speed induction generators are applied instead of other electric machines in wind power plants to be connected to the grid with flexible controllers. Nowadays one of the most important subjects in wind farms is control of output power delivered to the grid under utility disturbance. In this paper, a doubly-fed induction generator with external rotor resistance and power converters model as an external voltage source having an adjustable phase and amplitude with an ordinary turbine connected to one mass shaft model and also two mass shaft model, is used and controlled by a P voltage controller to control the output active power for typical high and low wind speeds under two conditions of utility disturbance; while time of disturbance is not too long to change the domain of external rotor voltage source and also while time is long and the domain of external rotor voltage decreases.Simulation results show that P voltage controller can control output active power under 27% stator voltage drop down for typical low wind speed and 11% stator voltage drop down for typical high wind speed in long time disturbance while 80% of rotor external voltage domain drops down under short time utility disturbance.

  11. Measuring Multiple Resistances Using Single-Point Excitation

    Science.gov (United States)

    Hall, Dan; Davies, Frank

    2009-01-01

    In a proposed method of determining the resistances of individual DC electrical devices connected in a series or parallel string, no attempt would be made to perform direct measurements on individual devices. Instead, (1) the devices would be instrumented by connecting reactive circuit components in parallel and/or in series with the devices, as appropriate; (2) a pulse or AC voltage excitation would be applied at a single point on the string; and (3) the transient or AC steady-state current response of the string would be measured at that point only. Each reactive component(s) associated with each device would be distinct in order to associate a unique time-dependent response with that device.

  12. Characteristics of ac capillary discharge produced in electrically conductive water solution

    Science.gov (United States)

    DeBaerdemaeker, F.; Simek, M.; Schmidt, J.; Leys, C.

    2007-05-01

    Basic electrical, optical and calorimetric characteristics of an ac (50 Hz) driven capillary discharge produced in a water solution were studied for initial water solution conductivity in the range 50-1000 µS cm-1. Typical current and voltage waveforms and emission intensities produced by several electronically excited species were recorded with high time resolution. The evolution of the electrical current, power and capillary resistance was inspected during positive ac half-cycle for various operational regimes. A fast relaxation of the discharge following a breakdown event was observed. Optical measurements indicate that radiative species are mostly generated during the first few hundreds of nanoseconds of plasma generation and that the average duration of plasma emission induced by a discharge pulse is of the order of a few microseconds. Results of calorimetric measurements are in good agreement with average electrical measurements and support the assumption that the discharge is a constant source of heat delivered to the liquid. Assuming that only a fraction of the heat released inside the capillary can be transported by conduction through the capillary wall and via its orifices, the processes of bubble formation, expulsion and re-filling the capillary with 'fresh' water must play a key role in maintaining a thermal balance during long-time steady-state operation of the device. Furthermore, a simplified numerical model and a first order energy deposition calculation prove the plausibility of the bubble breakdown mechanism.

  13. REALIZATION OF FUZZY-FILTER CONTROL ON A BRUSHLESS AC GENERATOR

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    The transistor voltage regulators have been widely adopted in the brushless AC generators in aircraft. This paper researches the digital voltage regulator. The paper presents the hardware platform of the digital voltage regulator, which is based on a DSP chip - TMS320C32. A novel fuzzy-filter control structure is developed from normal fuzzy control strategy. And the fuzzy-filter control algorithm is adopted in the hardware platform successfully. The computer simulation has been conducted. Some control parameters have been obtained through the simulation. The same parameters have been applied in the digital regulation experiments on a brushless AC generator. In the experiment, the digital voltage regulator results in good responses. From the experiment results, it can be seen that the new control algorithm is efficient for the digital voltage regulator.

  14. Modulation schemes with enhanced switch thermal distribution for single-phase AC-DC-AC reduced-switch converters

    DEFF Research Database (Denmark)

    Qin, Zian; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    ulation schemes can significantly change the performance of a power converter in steady state, and they have been extensively studied, but mostly directed to three-phase topologies, where triplen offsets are added. Single-phase systems, including ac-dc-ac systems, are less widely pursued, even...... among their switches, while keeping their dc-link voltages low. Single points of failure are thus minimized, allowing the converters to have longer lifetimes. Simulation and experimental results have demonstrated the intended performances and hence verifying the idea....

  15. Low-resistance strip sensors for beam-loss event protection

    Energy Technology Data Exchange (ETDEWEB)

    Ullán, M., E-mail: Miguel.Ullan@imb-cnm.csic.es [Centro Nacional de Microelectrónica (IMB-CNM, CSIC), Campus Universitario de Bellaterra, 08193 Barcelona (Spain); Benítez, V.; Quirion, D.; Zabala, M.; Pellegrini, G.; Lozano, M. [Centro Nacional de Microelectrónica (IMB-CNM, CSIC), Campus Universitario de Bellaterra, 08193 Barcelona (Spain); Lacasta, C.; Soldevila, U.; García, C. [Instituto de Fisica Corpuscular (IFIC, CSIC-UV), Valencia (Spain); Fadeyev, V.; Wortman, J.; DeFilippis, J.; Shumko, M.; Grillo, A.A; Sadrozinski, H.F.-W. [Santa Cruz Institute for Particle Physics (SCIPP), University of California Santa Cruz (UCSC), Santa Cruz, CA (United States)

    2014-11-21

    AC-coupled silicon strip sensors can be damaged in case of a beam loss due to the possibility of a large charge accumulation in the bulk, developing very high voltages across the coupling capacitors which can destroy them. Punch-through structures are currently used to avoid this problem helping to evacuate the accumulated charge as large voltages are developing. Nevertheless, previous experiments, performed with laser pulses, have shown that these structures can become ineffective in relatively long strips. The large value of the implant resistance can effectively isolate the “far” end of the strip from the punch-through structure leading to large voltages. We present here our developments to fabricate low-resistance strip sensors to avoid this problem. The deposition of a conducting material in contact with the implants drastically reduces the strip resistance, assuring the effectiveness of the punch-through structures. First devices have been fabricated with this new technology. Initial results with laser tests show the expected reduction in peak voltages on the low resistivity implants. Other aspects of the sensor performance, including the signal formation, are not affected by the new technology.

  16. A novel concept for stabilization of AC/DC network with UPFC

    Energy Technology Data Exchange (ETDEWEB)

    Pandey, R.K. [Banaras Hindu Univ., Inst. of Technology, Varanasi (India). Dept. of Electrical Engineering

    2006-07-01

    In a power system network, 2 regional grids can be interconnected by HVDC back-to-back. The 2 converter stations are connected through the DC link and the converters have their individual controls. The risk of network tripping can be significantly minimized by modulating the real and reactive power, thereby improving the stability of the AC/DC system. This paper described a unified power flow controller (UPFC), an innovative concept for stabilizing AC/DC networks. It also presented the results of a study that investigated the perturbation in AC bus voltages along with the effect on the stability deterioration. The new concept of control was proposed by embedding UPFC and then generating the control decisions to sufficiently stabilize the earlier ones. The Novel Discrete-Time model for AC/DC systems was used to study the complete system stability under varying perturbations of AC system voltage. The study revealed that the HVDC-SVC alone was not able to handle the perturbation of line to line voltage change after a certain value because the SVC cannot support external reactive power variations which are meant to regulate the Var requirements during converter control. In such situations, the UPFC along with the HVDC-SVC damped the oscillations, thereby adequately matching the real and reactive power demands. This combination can be used effectively in situations when the AC system bus voltage fluctuates due to changing P and Q requirements. 9 refs., 1 tab., 5 figs.

  17. High Voltage Distribution

    Science.gov (United States)

    Norbeck, Edwin; Miller, Michael; Onel, Yasar

    2010-11-01

    For detector arrays that require 5 to 10 kV at a few microamps each for hundreds of detectors, using hundreds of HV power supplies is unreasonable. Bundles of hundreds of HV cables take up space that should be filled with detectors. A typical HV module can supply 1 ma, enough current for hundreds of detectors. It is better to use a single HV module and distribute the current as needed. We show a circuit that, for each detector, measures the current, cuts off the voltage if the current exceeds a set maximum, and allows the HV to be turned on or off from a control computer. The entire array requires a single HV cable and 2 or 3 control lines. This design provides the same voltage to all of the detectors, the voltage set by the single HV module. Some additional circuitry would allow a computer controlled voltage drop between the HV and each individual detector.

  18. Implementationof Single Phasing, Over Voltage, Under Voltage, Protection of Three Phase Appliances without Using Microcontroller

    Directory of Open Access Journals (Sweden)

    Girish Chandra Thakur

    2015-05-01

    Full Text Available This paper tends to develop for protection for costly appliances which require three-phase AC supply for operation. Failure of any of the phases or sudden change in voltage makes the appliance prone to erratic functioning and may even lead to failure. Hence it is of paramount importance to monitor the availability of the three-phase supply and proper voltage supply and switch off the appliance in the event of failure of one or two phases or if required voltage level is not available. The power to the appliance should resume with the availability of all phases of the supply with proper voltage level. The main advantage of this protector circuit is that it protects three-phase appliances from failure of any phase as well as from fluctuation of voltage. The concept in future can be extended to developing a mechanism to send message to the authority via SMS by interfacing GSM modem. Details description of all types of faults is given below.

  19. A cascaded three-phase symmetrical multistage voltage multiplier

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Shahid [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia); Singh, G K [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia); Besar, R [Faculty of Engineering and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia); Muhammad, G [Faculty of Information Science and Technology, Multimedia University, Melaka Campus, 75450 Melaka (Malaysia)

    2006-10-15

    A cascaded three-phase symmetrical multistage Cockcroft-Walton voltage multiplier (CW-VM) is proposed in this report. It consists of three single-phase symmetrical voltage multipliers, which are connected in series at their smoothing columns like string of batteries and are driven by three-phase ac power source. The smoothing column of each voltage multiplier is charged twice every cycle independently by respective oscillating columns and discharged in series through load. The charging discharging process completes six times a cycle and therefore the output voltage ripple's frequency is of sixth order of the drive signal frequency. Thus the proposed approach eliminates the first five harmonic components of load generated voltage ripples and sixth harmonic is the major ripple component. The proposed cascaded three-phase symmetrical voltage multiplier has less than half the voltage ripple, and three times larger output voltage and output power than the conventional single-phase symmetrical CW-VM. Experimental and simulation results of the laboratory prototype are given to show the feasibility of proposed cascaded three-phase symmetrical CW-VM.

  20. High voltage engineering fundamentals

    CERN Document Server

    Kuffel, E; Hammond, P

    1984-01-01

    Provides a comprehensive treatment of high voltage engineering fundamentals at the introductory and intermediate levels. It covers: techniques used for generation and measurement of high direct, alternating and surge voltages for general application in industrial testing and selected special examples found in basic research; analytical and numerical calculation of electrostatic fields in simple practical insulation system; basic ionisation and decay processes in gases and breakdown mechanisms of gaseous, liquid and solid dielectrics; partial discharges and modern discharge detectors; and over

  1. Kirchhoff voltage law corrected for radiating circuits

    CERN Document Server

    Lara, Vitor

    2014-01-01

    When a circular loop composed by a RLC is put to oscillate, the oscillation will eventually vanish in an exponentially decaying current, even considering superconducting wires, due to the emission of electric and magnetic dipole radiation. In this work we propose a modification on the Kirchhoff voltage law by adding the radiative contributions to the energy loss as an effective resistance, whose value is relatively small when compared to typical resistance value, but fundamental to describe correctly real circuits. We have also analysed the change in the pattern of the radiation spectra emitted by the circuit as we vary both the effective and electrical resistance.

  2. Low-voltage gyrotrons

    Science.gov (United States)

    Glyavin, M. Yu.; Zavolskiy, N. A.; Sedov, A. S.; Nusinovich, G. S.

    2013-03-01

    For a long time, the gyrotrons were primarily developed for electron cyclotron heating and current drive of plasmas in controlled fusion reactors where a multi-megawatt, quasi-continuous millimeter-wave power is required. In addition to this important application, there are other applications (and their number increases with time) which do not require a very high power level, but such issues as the ability to operate at low voltages and have compact devices are very important. For example, gyrotrons are of interest for a dynamic nuclear polarization, which improves the sensitivity of the nuclear magnetic resonance spectroscopy. In this paper, some issues important for operation of gyrotrons driven by low-voltage electron beams are analyzed. An emphasis is made on the efficiency of low-voltage gyrotron operation at the fundamental and higher cyclotron harmonics. These efficiencies calculated with the account for ohmic losses were, first, determined in the framework of the generalized gyrotron theory based on the cold-cavity approximation. Then, more accurate, self-consistent calculations for the fundamental and second harmonic low-voltage sub-THz gyrotron designs were carried out. Results of these calculations are presented and discussed. It is shown that operation of the fundamental and second harmonic gyrotrons with noticeable efficiencies is possible even at voltages as low as 5-10 kV. Even the third harmonic gyrotrons can operate at voltages about 15 kV, albeit with rather low efficiency (1%-2% in the submillimeter wavelength region).

  3. Technical Aspects of the Advanced Camera For Surveys Repair (ACS-R)

    Science.gov (United States)

    Rinehart, Stephen; Cheng, Edward S.; Sirianni, Marco

    2008-01-01

    The ACS Repair (ACS-R) team includes contributors from NASA's Goddard Space Flight Center, Ball Aerospace, and Teledyne Imaging Sensors; It determined that all of the capabilities of the ACS could be restored and created a concept for the ACS-R component of SN4. ACSR will restore the WFC of ACS by replacing the existing CCD Electronics Box (CEB) with the CEB-Replacement (CEB-R) and providing power from a new Low Voltage Power Supply Replacement (LVPS-8). The new LVPS-R will also attempt to restore the HRC function by providing power through the original power bus. In this presentation, we faeus on the concept and technical aspects of the ACS-R.

  4. Low-temperature transport in ac-driven quantum dots in the Kondo regime

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Rosa; Aguado, Ramon; Platero, Gloria; Tejedor, Carlos

    2001-08-15

    We present a fully nonequilibrium calculation of the low-temperature transport properties of a quantum dot in the Kondo regime when an ac potential is applied to the gate. We solve a time-dependent Anderson model with finite on-site Coulomb interaction. The interaction self-energy is calculated up to second order in perturbation theory in the on-site interaction, in the context of the Keldysh nonequilibrium technique, and the effect of the ac voltage is taken into account exactly for all ranges of ac frequencies and ac intensities. The obtained linear conductance and time-averaged density of states of the quantum dot evolve in a nontrivial way as a function of the ac frequency and ac intensity of the harmonic modulation.

  5. Control of hybrid AC/DC microgrid under islanding operational conditions

    DEFF Research Database (Denmark)

    Ding, G.; Gao, F.; Zhang, S.

    2014-01-01

    This paper presents control methods for hybrid AC/DC microgrid under islanding operation condition. The control schemes for AC sub-microgrid and DC sub-microgrid are investigated according to the power sharing requirement and operational reliability. In addition, the key control schemes...... of interlinking converter with DC-link capacitor or energy storage, which will devote to the proper power sharing between AC and DC sub-microgrids to maintain AC and DC side voltage stable, is reviewed. Combining the specific control methods developed for AC and DC sub-microgrids with interlinking converter......, the whole hybrid AC/DC microgrid can manage the power flow transferred between sub-microgrids for improving on the operational quality and efficiency....

  6. Clopidogrel resistance: The way forward

    OpenAIRE

    Ray, Shuvanan

    2014-01-01

    Clopidogrel, a second generation thienopyridine has been the mainstay of ACS (Acute Coronary Syndrome) treatment for more than a decade. Clopidogrel Resistance has been associated with increased mortality in ACS patients with an increase in number of Stent Thrombosis. This review article tries to find out the causes of Clopidogrel Resistance, the main factors involving it, Laboratory evaluation of Clopidogrel Resistance. The overall incidence of Clopidogrel Resistance across the Globe & India...

  7. Component-Minimized Buck-Boost Voltage Source Inverters

    DEFF Research Database (Denmark)

    Gao, F.; Loh, P.C.; Blaabjerg, Frede;

    2007-01-01

    the additional voltage relationship between dc input and ac output which is beyond the expectation when continuous inductor current is assumed. These theoretical findings, together with the inverter practicality, have been confirmed in Matlab/PLECS simulations and  experimentally using laboratory implemented......This paper presents the design of buck-boost B4 inverters that can be derived from either Ćuk- or SEPIC-derived buck-boost B6 inverters. Unlike traditional inverters, the integration of front-end voltage boost circuitry and inverter circuitry allows it to perform buck-boost voltage inversion....... In order to form a distinct neutral potential in the corresponding voltage boost circuitry for correct B4 inverter operation, necessary modifications are derived step by step. The resulted dc networks with symmetrical placement of passive components allow complete charging and equal energy distribution...

  8. Time varying voltage combustion control and diagnostics sensor

    Science.gov (United States)

    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.

  9. Droop-free Distributed Control for AC Microgrids

    DEFF Research Database (Denmark)

    Nasirian, Vahidreza; Shafiee, Qobad; Guerrero, Josep M.

    2016-01-01

    guidelines are provided. Steady-state performance analysis shows that the proposed controller can accurately handle the global voltage regulation and proportional load sharing. An AC microgrid prototype is set up, where the controller performance, plug-and-play capability, and resiliency to the failure...... active power of each inverter with its neighbors’ and uses the difference to update the frequency and, accordingly, the phase angle of that inverter. The global dynamic model of the microgrid, including distribution grid, regulator modules, and the communication network, is derived, and controller design......A cooperative distributed secondary/primary control paradigm for AC microgrids is proposed. This solution replaces the centralized secondary control and the primary-level droop mechanism of each inverter with three separate regulators: voltage, reactive power, and active power regulators. A sparse...

  10. A random resistor network model of voltage trimming

    Energy Technology Data Exchange (ETDEWEB)

    Grimaldi, C [Laboratoire de Production Microtechnique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Maeder, T [Laboratoire de Production Microtechnique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Ryser, P [Laboratoire de Production Microtechnique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland); Straessler, S [Laboratoire de Production Microtechnique, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (Switzerland)

    2004-08-07

    In industrial applications, the controlled adjustment (trimming) of resistive elements via the application of high voltage pulses is a promising technique, with several advantages with respect to more classical approaches such as the laser cutting method. The microscopic processes governing the response to high voltage pulses depend on the nature of the resistor and on the interaction with the local environment. Here we provide a theoretical statistical description of voltage discharge effects on disordered composites by considering random resistor network models with different properties and processes due to the voltage discharge. We compare standard percolation results with biased percolation effects and provide a tentative explanation of the different scenarios observed during trimming processes.

  11. Device for monitoring cell voltage

    Science.gov (United States)

    Doepke, Matthias [Garbsen, DE; Eisermann, Henning [Edermissen, DE

    2012-08-21

    A device for monitoring a rechargeable battery having a number of electrically connected cells includes at least one current interruption switch for interrupting current flowing through at least one associated cell and a plurality of monitoring units for detecting cell voltage. Each monitoring unit is associated with a single cell and includes a reference voltage unit for producing a defined reference threshold voltage and a voltage comparison unit for comparing the reference threshold voltage with a partial cell voltage of the associated cell. The reference voltage unit is electrically supplied from the cell voltage of the associated cell. The voltage comparison unit is coupled to the at least one current interruption switch for interrupting the current of at least the current flowing through the associated cell, with a defined minimum difference between the reference threshold voltage and the partial cell voltage.

  12. High voltage pulse generator

    Science.gov (United States)

    Fasching, George E.

    1977-03-08

    An improved high-voltage pulse generator has been provided which is especially useful in ultrasonic testing of rock core samples. An N number of capacitors are charged in parallel to V volts and at the proper instance are coupled in series to produce a high-voltage pulse of N times V volts. Rapid switching of the capacitors from the paralleled charging configuration to the series discharging configuration is accomplished by using silicon-controlled rectifiers which are chain self-triggered following the initial triggering of a first one of the rectifiers connected between the first and second of the plurality of charging capacitors. A timing and triggering circuit is provided to properly synchronize triggering pulses to the first SCR at a time when the charging voltage is not being applied to the parallel-connected charging capacitors. Alternate circuits are provided for controlling the application of the charging voltage from a charging circuit to be applied to the parallel capacitors which provides a selection of at least two different intervals in which the charging voltage is turned "off" to allow the SCR's connecting the capacitors in series to turn "off" before recharging begins. The high-voltage pulse-generating circuit including the N capacitors and corresponding SCR's which connect the capacitors in series when triggered "on" further includes diodes and series-connected inductors between the parallel-connected charging capacitors which allow sufficiently fast charging of the capacitors for a high pulse repetition rate and yet allow considerable control of the decay time of the high-voltage pulses from the pulse-generating circuit.

  13. Investigation of phase-wise voltage regulator control logics for compensating voltage deviations in an experimental low voltage network

    DEFF Research Database (Denmark)

    Hu, Junjie; Zecchino, Antonio; Marinelli, Mattia

    2016-01-01

    either locally or remotely. To evaluate and compare the control performances of the three control logics, all the tests use the same loading profiles. The experimental results indicate that the modified line compensation control can regulate voltage in a safe band in the case of various load......This paper investigates the control logics of an on-load tap-changer (OLTC) transformer by means of an experimental system validation. The experimental low-voltage unbalanced system consists of a decoupled single-phase OLTC transformer, a 75-metre 16 mm2 cable, a controllable single-phase resistive...... load and an electric vehicle, which has the vehicle-to-grid function. Three control logics of the OLTC transformer are described in the study. The three control logics are classified based on their control objectives and control inputs, which include network currents and voltages, and can be measured...

  14. Capturing power at higher voltages from arrays of microbial fuel cells without voltage reversal

    KAUST Repository

    Kim, Younggy

    2011-01-01

    Voltages produced by microbial fuel cells (MFCs) cannot be sustainably increased by linking them in series due to voltage reversal, which substantially reduces stack voltages. It was shown here that MFC voltages can be increased with continuous power production using an electronic circuit containing two sets of multiple capacitors that were alternately charged and discharged (every one second). Capacitors were charged in parallel by the MFCs, but linked in series while discharging to the circuit load (resistor). The parallel charging of the capacitors avoided voltage reversal, while discharging the capacitors in series produced up to 2.5 V with four capacitors. There were negligible energy losses in the circuit compared to 20-40% losses typically obtained with MFCs using DC-DC converters to increase voltage. Coulombic efficiencies were 67% when power was generated via four capacitors, compared to only 38% when individual MFCs were operated with a fixed resistance of 250 Ω. The maximum power produced using the capacitors was not adversely affected by variable performance of the MFCs, showing that power generation can be maintained even if individual MFCs perform differently. Longer capacitor charging and discharging cycles of up to 4 min maintained the average power but increased peak power by up to 2.6 times. These results show that capacitors can be used to easily obtain higher voltages from MFCs, allowing for more useful capture of energy from arrays of MFCs. © 2011 The Royal Society of Chemistry.

  15. Control the aggregation of model amyloid insulin protein under ac-electric fields

    Science.gov (United States)

    Zheng, Zhongli; Jing, Benxin; Zhu, Y. Elaine

    2013-03-01

    In vitro experiments have been widely used to characterize the misfolding/unfolding pathway characteristic of amylodogenic proteins. Conversion from natively folded amyloidogenic proteins to oligomers via nucleation is the accepted path to fibril formation upon heating over a certain lag time period. In an alternative engineering approach to manipulate and control protein aggregation, we have investigated the aggregation kinetics of insulin, a well-established amyloid model protein, under applied ac-electric fields of varied ac-frequency and voltage at room temperature. Using fluorescence correlation spectroscopy and fluorescence imaging, we have observed that the insulin aggregation can occur at much shortened lag time under applied ac-electric fields, when a critical ac-voltage is exceeded. The strong dependence of lag time on ac-frequency over a narrow range of 500 Hz-5 kHz indicates the effect of ac-electroosmosis on the diffusion controlled process of insulin nucleation. Yet, no difference of conformational structure is detected with insulin under applied ac-fields, suggesting the equivalence of ac-polarization to the conventional thermal activation process for insulin aggregation.

  16. Measurement of Dynamic Resistance in Resistance Spot Welding

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side...... of the transformer in resistance welding machines, implying defects from induction noise and interference with the leads connected to the electrodes for measuring the voltage. In this study, the dynamic resistance is determined by measuring the voltage on the primary side and the current on the secondary side......, as another application, the proposed method is used to measure the faying surface contact resistance....

  17. Measurement of Dynamic Resistance in Resistance Spot Welding

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side...... of the transformer in resistance welding machines, implying defects from induction noise and interference with the leads connected to the electrodes for measuring the voltage. In this study, the dynamic resistance is determined by measuring the voltage on the primary side and the current on the secondary side......, as another application, the proposed method is used to measure the faying surface contact resistance....

  18. Transient Voltage Stability Analysis and Improvement of A Network with different HVDC Systems

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2011-01-01

    the theoretical analysis and the improved control method, real time simulation model of a hybrid multi-infeed HVDC system based on western Danish power system is established in RTDS™. Simulation results show that the enhanced transient voltage stability can be achieved.......This paper presents transient voltage stability analysis of an AC system with multi-infeed HVDC links including a traditional LCC HVDC link and a VSC HVDC link. It is found that the voltage supporting capability of the VSC-HVDC link is significantly influenced by the tie-line distance between...... the two links and the size of loads. In order to improve the transient voltage stability, a voltage adjusting method is proposed in this paper. A voltage increment component has been introduced into the outer voltage control loop under emergency situation caused by severe grid faults. In order to verify...

  19. Simulation of an ac electro-osmotic pump with step microelectrodes

    Science.gov (United States)

    Kim, Byoung Jae; Lee, Seung-Hyun; Rezazadeh, Soghra; Sung, Hyung Jin

    2011-05-01

    Pumps with step microelectrodes subjected to an ac voltage are known to have faster pumping rates than those with planar asymmetric microelectrodes. The driving force for pumping in these systems is ac electro-osmosis. This paper aims to understand the flow behaviors of pumps with step microelectrodes by using a realistic model applicable to high external voltages. This model takes the steric effect due to the finite sizes of ions into account and copes with the exponential sensitivity of the counterion concentration to voltage. The effects on the pumping flow rate of varying the pump parameters were investigated. The geometrical parameters were optimized, and the effects of varying the ac frequency and amplitude were examined. The electrical potential of the fluid and the electrical charge at the electrode surface were solved simultaneously, and the Stokes equation was used to describe the fluid flow.

  20. Nanorod dynamics in ac electric fields

    Energy Technology Data Exchange (ETDEWEB)

    Ruda, H E; Shik, A [Centre for Advanced Nanotechnology, University of Toronto, Toronto, M5S 3E3 (Canada)

    2010-06-11

    Metal and semiconductor nanorods polarized by an external electric field tend to align parallel to this field. We derived the equation of motion for this alignment, taking into account electrostatic forces, thermal fluctuations and viscous resistance of the liquid the nanorods are suspended in. It was solved for a strong ac electric field, as well as for the combination of strong dc and weak ac fields. The results were used for calculations of the capacity of the nanorod solution, its frequency dispersion and dependence on the field strength. Modification of the nanorod absorption spectra under the influence of an electric field was also considered. It was shown that metal nanorods in laser radiation, with the frequency belonging to the interval between longitudinal and transverse plasmon modes, tend to align perpendicular, rather than parallel, to the optical electric field.

  1. Power Electronic Transformer based Three-Phase PWM AC Drives

    Science.gov (United States)

    Basu, Kaushik

    A Transformer is used to provide galvanic isolation and to connect systems at different voltage levels. It is one of the largest and most expensive component in most of the high voltage and high power systems. Its size is inversely proportional to the operating frequency. The central idea behind a power electronic transformer (PET) also known as solid state transformer is to reduce the size of the transformer by increasing the frequency. Power electronic converters are used to change the frequency of operation. Steady reduction in the cost of the semiconductor switches and the advent of advanced magnetic materials with very low loss density and high saturation flux density implies economic viability and feasibility of a design with high power density. Application of PET is in generation of power from renewable energy sources, especially wind and solar. Other important application include grid tied inverters, UPS e.t.c. In this thesis non-resonant, single stage, bi-directional PET is considered. The main objective of this converter is to generate adjustable speed and magnitude pulse width modulated (PWM) ac waveforms from an ac or dc grid with a high frequency ac link. The windings of a high frequency transformer contains leakage inductance. Any switching transition of the power electronic converter connecting the inductive load and the transformer requires commutation of leakage energy. Commutation by passive means results in power loss, decrease in the frequency of operation, distortion in the output voltage waveform, reduction in reliability and power density. In this work a source based partially loss-less commutation of leakage energy has been proposed. This technique also results in partial soft-switching. A series of converters with novel PWM strategies have been proposed to minimize the frequency of leakage inductance commutation. These PETs achieve most of the important features of modern PWM ac drives including 1) Input power factor correction, 2) Common

  2. High voltage load resistor array

    Energy Technology Data Exchange (ETDEWEB)

    Lehmann, Monty Ray [Smithfield, VA

    2005-01-18

    A high voltage resistor comprising an array of a plurality of parallel electrically connected resistor elements each containing a resistive solution, attached at each end thereof to an end plate, and about the circumference of each of the end plates, a corona reduction ring. Each of the resistor elements comprises an insulating tube having an electrode inserted into each end thereof and held in position by one or more hose clamps about the outer periphery of the insulating tube. According to a preferred embodiment, the electrode is fabricated from stainless steel and has a mushroom shape at one end, that inserted into the tube, and a flat end for engagement with the end plates that provides connection of the resistor array and with a load.

  3. Transient demonstration of exciton behaviours in solid state cathodoluminescence under different driving voltage

    Institute of Scientific and Technical Information of China (English)

    Zhang Fu-Jun; Zhao Su-Ling; Xu Zheng; Huang Jin-Zhao; Xu Xu-Rong

    2007-01-01

    In the solid state cathodoluminescence (SSCL), organic materials were excited by hot electrons accelerated in silicon oxide (SiO2) layer under alternating current (AC). In this paper exciton behaviours were analysed by using transient spectra under different driving voltages. The threshold voltages of SSCL and exciton ionization were obtained from the transient spectra. The recombination radiation occurred when the driving voltage went beyond the threshold voltage of exciton ionization. Prom the transient spectrum of two kinds of luminescence (exciton emission and recombination radiation), it was demonstrated that recombination radiation should benefit from the exciton ionization.

  4. Power flow control and voltage stability limit: regulating transformer versus UPFC

    Energy Technology Data Exchange (ETDEWEB)

    Haque, M.H. [Nanyang Technological Univ., Center for Advanced Power Electronics, Nanyang (Singapore)

    2004-05-01

    Power flow through an AC transmission line can be controlled by injecting an adjustable compensating voltage in series with the line. This paper evaluates and compares the power flow control ranges of a simple system obtained by injecting an adjustable series compensating voltage produced by a regulating transformer and unified power flow controller. The static voltage stability limits of the system with a regulating transformer and unified power flow controller are also determined and compared. In evaluating the power flow control ranges and voltage stability limits, the transmission line of the system is modelled in four different ways. The results obtained for various line models are also compared. (Author)

  5. Voltage Regulators for Photovoltaic Systems

    Science.gov (United States)

    Delombard, R.

    1986-01-01

    Two simple circuits developed to provide voltage regulation for highvoltage (i.e., is greater than 75 volts) and low-voltage (i.e., is less than 36 volts) photovoltaic/battery power systems. Use of these circuits results in voltage regulator small, low-cost, and reliable, with very low power dissipation. Simple oscillator circuit controls photovoltaic-array current to regulate system voltage and control battery charging. Circuit senses battery (and system) voltage and adjusts array current to keep battery voltage from exceeding maximum voltage.

  6. Acúmulo de nutrientes em soja convencional e soja RR em diferentes tipos de controle de planta daninha Nutrient accumulation in conventional and glyphosate-resistant soybean under different types of weed control

    National Research Council Canada - National Science Library

    L.H.S. Zobiole; R.S. Oliveira JR; J. Constantin; A. Oliveira JR; C. Castro; F.A. Oliveira; R.J. Kremer; A. Moreira; L.M Romagnoli

    2012-01-01

    ... acúmulo de nutrientes em diferentes estádios fenológicos entre os cultivares BRS 184 (convencional) e BRS 243 RR (transgênico), com mesmo ciclo vegetativo e reprodutivo, sob diferentes sistemas de manejo de plantas daninhas...

  7. Distributed Low Voltage Ride-Through Operation of Power Converters in Grid-Connected Microgrids under Voltage Sags

    DEFF Research Database (Denmark)

    Zhao, Xin; Meng, Lexuan; Dragicevic, Tomislav;

    2015-01-01

    the voltage in all phases at AC common bus. However, since the line admittances from each converter to point of common coupling (PCC) are not identical, the injected reactive power may not be equally shared. In order to achieve low voltage ride through (LVRT) capability along with a good power sharing...... accuracy, a hierarchical control strategy is proposed in this paper. Droop control and virtual impedance is applied in primary control loop while secondary control loop is based on dynamic consensus algorithm (DCA). Experiments are conducted to verify the effectiveness of the proposed control strategy....

  8. A Review on Power System Voltage Stability and Optimization Techniques

    Directory of Open Access Journals (Sweden)

    T. Madhuranthaka

    2016-11-01

    Full Text Available Power system voltage stability is a one of the major focused areas in recent days due to mismatch between generation and demand. Maintenance of voltage stability is a challenging issue in planning and security assessment of power systems. Voltage stability is the ability of a power system to maintain steady acceptable voltages at all buses in the power system under normal operating conditions and after being subjected to a disturbance. Long-term voltage instability problems can occur in heavily loaded systems where the electrical distance is large between the generator and the load. Timely application of reactive power compensation or load shedding may prevent this type of voltage instability. System reactive power handling capacity can be improved with Flexible AC Transmission System (FACTS devices. Identification of critical system locations to undertake appropriate remedial measures in operation is the concern. This paper reviews the performance of various types FACTS controllers in power system voltage stability problem and focuses on different optimization methods implemented for optimal placement and sizing of FACTS devices to minimize power losses.

  9. New zero voltage switching DC converter with flying capacitors

    Science.gov (United States)

    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.

  10. High performance AC drives

    CERN Document Server

    Ahmad, Mukhtar

    2010-01-01

    This book presents a comprehensive view of high performance ac drives. It may be considered as both a text book for graduate students and as an up-to-date monograph. It may also be used by R & D professionals involved in the improvement of performance of drives in the industries. The book will also be beneficial to the researchers pursuing work on multiphase drives as well as sensorless and direct torque control of electric drives since up-to date references in these topics are provided. It will also provide few examples of modeling, analysis and control of electric drives using MATLAB/SIMULIN

  11. Pulse-Width Control in Ladder Structure Four-Phase Rectifier for AC-Electromotive

    Science.gov (United States)

    Ivanov, V. V.; Myatez, S. V.; Langeman, E. G.; Schurov, N. I.

    2016-04-01

    Based on these studies the ways of power factor of the single-phase rectifiers operating in a single-phase AC network improving are suggested. The ladder four-phase rectifier is offered as a technical mean using a pulse-width method of controlling the rectified voltage. The pulse-width control efficiency as a way of the power factor rectifier with a ladder structure for AC electromotive improving is evaluated.

  12. A Series-LC-Filtered Active Damper for AC Power Electronics Based Power Systems

    DEFF Research Database (Denmark)

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

    2015-01-01

    This paper proposes an active damper with a series LC-filter for suppressing resonances in an ac power electronics based power system. The added filter capacitor helps to lower the voltage stress of the converter to be used for implementing the damper. Unlike active filters for the compensation...... is built, where the damper is integrated into a grid-connected converter. The results obtained from the experiments demonstrate the stability enhancement of ac power electronics based power systems by the active damper....

  13. Marine High Voltage Power Conditioning and Transmission System with Integrated Storage DE-EE0003640 Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Frank Hoffmann, PhD; Aspinall, Rik

    2012-12-10

    Design, Development, and test of the three-port power converter for marine hydrokinetic power transmission. Converter provides ports for AC/DC conversion of hydrokinetic power, battery storage, and a low voltage to high voltage DC port for HVDC transmission to shore. The report covers the design, development, implementation, and testing of a prototype built by PPS.

  14. Five-Phase Five-Level Open-Winding/Star-Winding Inverter Drive for Low-Voltage/High-Current Applications

    DEFF Research Database (Denmark)

    Padmanaban, Sanjeevi Kumar; Blaabjerg, Frede; Wheeler, Patrick

    2016-01-01

    This paper work proposed a five-phase five-level open-/star-winding multilevel AC converter suitable for low-voltage/high-current applications. Modular converter consists of classical two-level five-phase voltage source inverter (VSI) with slight reconfiguration to serve as a multilevel converter...

  15. Performance analysis of resistive switching devices based on BaTiO3 thin films

    Science.gov (United States)

    Samardzic, Natasa; Kojic, Tijana; Vukmirovic, Jelena; Tripkovic, Djordjije; Bajac, Branimir; Srdic, Vladimir; Stojanovic, Goran

    2016-03-01

    Resitive switching devices, memristors, have recenty attracted much attention due to promising performances and potential applications in the field of logic and memory devices. Here, we present thin film BaTiO3 based memristor fabricated using ink-jet printing technique. Active material is a single layer barium titanate film with thickness of ̴100 nm, sandwitched between metal electodes. Printing parameters were optimized aiming to achieve stable drop flow and uniform printed layer. Current-voltage characteristics show typical memristive behavior with pinched hysteresis loop crossed at the origin, with marked differences between High Resistive State (HRS) and Low Resistive State (LRS). Obtained resistive states are stable during numerous switching processes. The device also shows unipolar switching effect for negative voltage impulses. Variable voltage impulse amplitudes leads to the shifting of the energy levels of electode contacts resulting in changing of the overall current through the device. Structural charcterization have been performed using XRD analysis and SEM micrography. High-temperature current-voltage measurements combined with transport parameter analysis using Hall efect measurement system (HMS 3000) and Impedance Analyzer AC measurements allows deeper insigth into conduction mechanism of ferroelectric memristors.

  16. Measurement of AC loss of superconductors by vaporizing method

    Energy Technology Data Exchange (ETDEWEB)

    Wakabayashi, Hiroshi; Isono, Takaaki; Matsui, Kunihiro; Fujisaki, Reishi; Nunoya, Yoshihiko; Koizumi, Norikiyo; Takahashi, Yoshikazu; Tsuji, Hiroshi [Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan). Naka Fusion Research Establishment

    1995-07-01

    In Japan Atomic Energy Research Institute, the development of superconducting pulse conductors for next period nuclear fusion reactors has been carried out. For these conductors, the rated current of 46 kA and the rated magnetic field of 13T are demanded. When the pulse excitation of superconductors is carried out, AC loss arises, and the temperature of the superconductors rises, and when it exceeds a certain value, the superconducting state cannot be maintained. Therefore, the AC loss of pulse conductors must be limited to a low value. It is difficult to evaluate the AC loss of superconductors by calculation, therefore, it is evaluated by actual measurement. There are magnetizing method and vaporizing method for measuring the AC loss. This time, the equipment for measuring the AC loss of 40 kA class superconductors by vaporizing method which measures the helium gas quantity vaporizing at the time of AC loss occurrence was designed and manufactured for the first time. The method of measuring the AC loss, the structure of the measuring equipment, the helium gas recovering part and the measuring part, the countermeasures for preventing helium gas leakage, the resistance heater for calibration, and the results of measurement are reported. (K.I.)

  17. Design and Implementation of a High-Voltage Generator with Output Voltage Control for Vehicle ER Shock-Absorber Applications

    Directory of Open Access Journals (Sweden)

    Chih-Lung Shen

    2013-01-01

    Full Text Available A self-oscillating high-voltage generator is proposed to supply voltage for a suspension system in order to control the damping force of an electrorheological (ER fluid shock absorber. By controlling the output voltage level of the generator, the damping force in the ER fluid shock absorber can be adjusted immediately. The shock absorber is part of the suspension system. The high-voltage generator drives a power transistor based on self-excited oscillation, which converts dc to ac. A high-frequency transformer with high turns ratio is used to increase the voltage. In addition, the system uses the car battery as dc power supply. By regulating the duty cycle of the main switch in the buck converter, the output voltage of the buck converter can be linearly adjusted so as to obtain a specific high voltage for ER. The driving system is self-excited; that is, no additional external driving circuit is required. Thus, it reduces cost and simplifies system structure. A prototype version of the actual product is studied to measure and evaluate the key waveforms. The feasibility of the proposed system is verified based on experimental results.

  18. Requirement of ultra-high voltage GIS arrester to voltage gradient of metal-oxide varistor

    Institute of Scientific and Technical Information of China (English)

    HE JinLiang; HU Jun; MENG BoWen; ZHANG Bo; ZHU Bin; CHEN ShuiMing; ZENG Rong

    2009-01-01

    The surge arrestor with excellent protection characteristics would decrease the overvoltage level ap-plied on the power apparatus to reduce their insulation levels and manufacturing bottleneck. The ar-restor for the 1000-kV ultra-high voltage ac power transmission system is designed as tank-type structure. The field-circuit combination numerical method combining the three-dimensional finite ele-ment method with circuit is proposed to analyze the potential distribution of GIS arrester. By comparing several design schemes, the most effective method to improve the potential distribution along the varistor column is to increase the voltage gradient of the ZnO varistor. Synthesizing several influential factors, the suitable voltage gradient of ZnO varistor should be controlled to 435 V/mm, and the re-sulted nonuniform degree of the potential distribution along the varistor column inside the GIS arrestor would be controlled smaller than 10%. The result in this paper provides the fundamental technical in-dex for the study of the high voltage gradient ZnO varistors.

  19. Voltage source inverters for high power, variable-voltage DC power sources

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Z. [Department of Engineering and Technology, De Montfort University, Queens Building, The Gateway, Leicester, LE1 9BH, (United Kingdom); Spooner, E. [School of Engineering, University of Durham, Science Laboratories, South Rd, Durham, DRI 3LE, (United Kingdom)

    2001-09-01

    The paper discusses the applications of voltage source inverter (VSI) based power electronic systems for interfacing variable-voltage DC sources to the grid. A variable-speed wind power conversion system is used for illustration, where the VSI-based interface needs to convert a variable DC voltage to a nearly constant AC voltage with high-quality power. The power control principles of VSI are described. Various system configurations and switching strategies are examined by analysis, simulation and experimental methods. It is shown that better utilisation of semiconductors and more flexible control may be achieved by using a separately controlled DC link, rather than a directly connected VSI that has to operate at a lower modulation ratio at higher power. In some cases, multipulse inverter structures may be preferred, despite higher component count, because of reduced switching losses, fault tolerance and the absence of filters. The solutions developed in the study could be applied at a different scale to other renewable energy sources, such as wave or solar photovoltaic devices. (Author)

  20. Requirement of ultra-high voltage GIS arrester to voltage gradient of metal-oxide varistor

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    The surge arrester with excellent protection characteristics would decrease the overvoltage level ap- plied on the power apparatus to reduce their insulation levels and manufacturing bottleneck. The arrester for the 1000-kV ultra-high voltage ac power transmission system is designed as tank-type structure. The field-circuit combination numerical method combining the three-dimensional finite element method with circuit is proposed to analyze the potential distribution of GIS arrester. By comparing several design schemes, the most effective method to improve the potential distribution along the varistor column is to increase the voltage gradient of the ZnO varistor. Synthesizing several influential factors, the suitable voltage gradient of ZnO varistor should be controlled to 435 V/mm, and the resulted nonuniform degree of the potential distribution along the varistor column inside the GIS arrester would be controlled smaller than 10%. The result in this paper provides the fundamental technical index for the study of the high voltage gradient ZnO varistors.

  1. A 900-2400 MHz AC-DC Rectifier Circuit for Radio Frequency Energy Harvesting

    Directory of Open Access Journals (Sweden)

    Rosli M.A.

    2016-01-01

    Full Text Available This paper presents a 900-2400 MHz AC-DC rectifier circuit for radio frequency (RF energy harvesting. The proposed circuit consists of a rectifier and charge pump. The multi-stage NMOS RF-DC rectifier circuit is designed to convert the AC signal to DC signal while the charge pump helps to amplify the DC amplitude. The proposed circuits are designed and simulated using CMOS 0.13-μm technology. The simulation results show that the proposed circuit able to produce 2.9 V DC voltage at 10 kΩ load with an input voltage of 150 mV.

  2. Fuzzy efficiency optimization of AC induction motors

    Science.gov (United States)

    Jani, Yashvant; Sousa, Gilberto; Turner, Wayne; Spiegel, Ron; Chappell, Jeff

    1993-01-01

    This paper describes the early states of work to implement a fuzzy logic controller to optimize the efficiency of AC induction motor/adjustable speed drive (ASD) systems running at less than optimal speed and torque conditions. In this paper, the process by which the membership functions of the controller were tuned is discussed and a controller which operates on frequency as well as voltage is proposed. The membership functions for this dual-variable controller are sketched. Additional topics include an approach for fuzzy logic to motor current control which can be used with vector-controlled drives. Incorporation of a fuzzy controller as an application-specific integrated circuit (ASIC) microchip is planned.

  3. VOLTAGE REGULATORS ASYNCHRONOUS GENERATORS

    Directory of Open Access Journals (Sweden)

    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. Geomagnetism and Induced Voltage

    Science.gov (United States)

    Abdul-Razzaq, W.; Biller, R. D.

    2010-01-01

    Introductory physics laboratories have seen an influx of "conceptual integrated science" over time in their classrooms with elements of other sciences such as chemistry, biology, Earth science, and astronomy. We describe a laboratory to introduce this development, as it attracts attention to the voltage induced in the human brain as it…

  5. High-voltage picoamperemeter

    Energy Technology Data Exchange (ETDEWEB)

    Bugl, Andrea; Ball, Markus; Boehmer, Michael; Doerheim, Sverre; Hoenle, Andreas; Konorov, Igor [Technische Universitaet Muenchen, Garching (Germany); Ketzer, Bernhard [Technische Universitaet Muenchen, Garching (Germany); Helmholtz-Institut fuer Strahlen- und Kernphysik, Bonn (Germany)

    2014-07-01

    Current measurements in the nano- and picoampere region on high voltage are an important tool to understand charge transfer processes in micropattern gas detectors like the Gas Electron Multiplier (GEM). They are currently used to e.g. optimize the field configuration in a multi-GEM stack to be used in the ALICE TPC after the upgrade of the experiment during the 2nd long shutdown of the LHC. Devices which allow measurements down to 1pA at high voltage up to 6 kV have been developed at TU Muenchen. They are based on analog current measurements via the voltage drop over a switchable shunt. A microcontroller collects 128 digital ADC values and calculates their mean and standard deviation. This information is sent with a wireless transmitting unit to a computer and stored in a root file. A nearly unlimited number of devices can be operated simultaneously and read out by a single receiver. The results can also be displayed on a LCD directly at the device. Battery operation and the wireless readout are important to protect the user from any contact to high voltage. The principle of the device is explained, and systematic studies of their properties are shown.

  6. AC Optimal Power Flow

    Energy Technology Data Exchange (ETDEWEB)

    2016-10-04

    In this work, we have implemented and developed the simulation software to implement the mathematical model of an AC Optimal Power Flow (OPF) problem. The objective function is to minimize the total cost of generation subject to constraints of node power balance (both real and reactive) and line power flow limits (MW, MVAr, and MVA). We have currently implemented the polar coordinate version of the problem. In the present work, we have used the optimization solver, Knitro (proprietary and not included in this software) to solve the problem and we have kept option for both the native numerical derivative evaluation (working satisfactorily now) as well as for analytical formulas corresponding to the derivatives being provided to Knitro (currently, in the debugging stage). Since the AC OPF is a highly non-convex optimization problem, we have also kept the option for a multistart solution. All of these can be decided by the user during run-time in an interactive manner. The software has been developed in C++ programming language, running with GCC compiler on a Linux machine. We have tested for satisfactory results against Matpower for the IEEE 14 bus system.

  7. HVDC-AC system interaction from AC harmonics. Volume 1. Harmonic impedance calculations. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R

    1982-09-01

    Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.

  8. HVDC-AC system interaction from AC harmonics. Volume 1. Harmonic impedance calculations. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, G D; Chow, J H; Lindh, C B; Miller, N W; Numrich, F H; Price, W W; Turner, A E; Whitney, R R

    1982-09-01

    Improved methods are needed to characterize ac system harmonic behavior for ac filter design for HVDC systems. The purpose of this General Electric Company RP1138 research is to evaluate the present filter design practice and to investigate methods for calculating system harmonic impedances. An overview of ac filter design for HVDC systems and a survey of literature related to filter design have been performed. Two methods for calculating system harmonic impedances have been investigated. In the measurement method, an instrumentation system for measuring system voltage and current has been assembled. Different schemes of using the measurements to calculate system harmonic impedances have been studied. In the analytical method, a procedure to include various operating conditions has been proposed. Computer programs for both methods have been prepared, and the results of the measurement and analytical methods analyzed. A conclusion of the project is that the measurement and analytical methods both provided reasonable results. There are correlations between the measured and analytical results for most harmonics, although there are discrepancies between the assumptions used in the two methods. A sensitivity approach has been proposed to further correlate the results. From the results of the analysis, it is recommended that both methods should be tested further. For the measurement method, more testing should be done to cover different system operating conditions. In the analytical method, more detailed models for representing system components should be studied. In addition, alternative statistical and sensitivity approaches should be attempted.

  9. DSP Based Control Implementation of an AC/DC Converter with Improved Input Current Distortion

    Directory of Open Access Journals (Sweden)

    WISUTMETHEEKORN, P.

    2011-05-01

    Full Text Available This paper presents a digital signal processor based control of an AC/DC converter with nearly unity power factor. Normally, the output voltage of a single-phase AC/DC converter comprises a voltage ripple with twice line-frequency. This affects the voltage control loop and leads to the converter input current distortion. The purposed method is designed to avoid the effect of the output voltage ripple. To verify the proposed control method, MATLAB/Simulink is used for system simulation. A hardware prototype is setup. A low cost digital signal processing chip dsPIC30F4011 is employed as a digital controller to control a CUK AC/DC converter. The converter specifications are 48V output voltage and 250W output power. From the simulation and the experimental results shown that the input current distortion of the purposed system is reduced and lower than the AC/DC converter that controlled by the conventional proportional-integral controller.

  10. Interpretation on Partial Discharge of Typical Insulation Model Under Oscillating Impulse Voltage

    Institute of Scientific and Technical Information of China (English)

    SUN Zhenquan; ZHAO Xuefeng; LI Jisheng; LI Yanming

    2012-01-01

    The aim of this paper was to give an overview on partial discharges under oscillating impulse voltage.Three models(void in solid,needle-plate in air and oil) were presented,which describe the stochastic discharge process and represent internal discharges in solids and corona in air or silicon oil.Moreover,an air cored Rogowski coil and a sampling resistor for partial discharge(PD) measurement were developed and introduced in this paper.PD inception and extinction voltages(PDIV,PDEV) under single oscillating impulse voltage and AC voltage were investigated with different test samples.Experimental results firstly revealed that the PD inception voltage(PDIV) decreased with increasing applied voltage;secondly the PD inception voltage for three different insulating materials,showed an escalating trend with increasing frequency of the applied voltage.It was proven that the characteristics of PD under oscillating impulse voltage were identical to the features under AC voltage,which could be measured with the phase resolved partial discharge analysis(PRPDA) technique.Based on the reorganization and analysis of PDs under oscillating impulse voltage,the information about insulation defects was extracted from the measured data and used for estimating the risk of insulation failure of the equipment.

  11. High Voltage Design Guide. Volume V. Spacecraft

    Science.gov (United States)

    1983-01-01

    connector are soldered, with the possible exception of very high voltage points. Even then rudimentary connectors such as that shown In figura 13 ar used...addition, large stresses will be imposed on the struc- tural (high resistance) member. This conductor movement will flex and stretch the conductors, placing...materials used for airplane systems provided they meet the electrical, chemical, and mechanical characteristic requirements imposed by the design

  12. 雨雪天气下特高压交流单回试验线段电晕损失实测分析%Analysis on Corona Loss Measurement of Ultra High Voltage AC Single Circuit Test Line in Rain and Snow Weather Conditions

    Institute of Scientific and Technical Information of China (English)

    律方成; 尤少华; 刘云鹏; 万启发

    2011-01-01

    In order to research corona loss characteristic of ultra high voltage(UHV) AC power transmission line in rain and snow weather conditions,UHV AC test base single circuit test lines were experimentally studied.Optical-electric digital corona loss monitoring system of transmission line was applied to realize the real-time online measurement of UHV AC test line corona loss wholly of the day,and to analyze corona losses under different rain rates and heavy snow atmosphere conditions according to monitoring results.The research results show that single phase corona loss per meter of UHV AC single circuit test line under rain is 20~60 W/m,under heavy rain the monitored maximum results per meter of the test line are 53.54 W/m for the side phase,62.95 W/m for the middle phase,which was fit to the estimate values as adopting equivalent rainfall rate.Corona loss increases nonlinearly as rainfall rate increases,and saturates gradually,thus a abecedarian fitting model between rainfall rate and corona loss of 8×LGJ-500/35 bundle conductors is obtained.Corona loss measurements of UHV AC single circuit test line in the test provide a reference for UHV AC transmission line conductors mode selection,design,and economy characteristic evaluation.%为了研究特高压交流输电线路在雨天、雪天气象条件下的电晕损失特性,基于我国特高压交流试验基地单回试验线段展开实测研究,采用研制的光电数字化输电线路电晕损失监测系统,实现了试验线段电晕损失全天候条件下实时在线测量,根据监测结果分析不同降雨率及大雪气象条件下电晕损失。研究结果表明,正常运行电压下,特高压交流单回试验线段雨天单相单位长度电晕损失约为20~60 W/m,在大雪气象条件下,根据监测结果,特高压交流单回试验线段单位长度电晕损失最大值为:边相达到53.54 W/m,中相达到62.95 W/m,与等值降雨率推算结果较为符合。电晕损失随降雨率增

  13. Emergency operation of a 3AC 50Hz power grid in the Loetschberg base tunnel; Notbetrieb der Energieversorgung 3AC 50Hz im Loetschberg-Basistunnel

    Energy Technology Data Exchange (ETDEWEB)

    Stadelmann, M. [BLS AG, Ressort Bahnstrom, Bern (Switzerland); Boss, J. [BKW FMB Energie AG, Spiez (Switzerland)

    2007-11-15

    At latest after 90 min after tripping of the normal supply a special isle grid energized from the power plant of Kandergrund feeds the numerous users in the base tunnel with 3 AC 50 hz. This prevents them from damages and train operation can be assured immediately after return of normal grid voltage. (orig.)

  14. A Versatile Control Scheme For Dynamic Voltage Restorer To Limit Downstream Fault Currents

    Directory of Open Access Journals (Sweden)

    A.Nagendra

    2014-12-01

    Full Text Available The Dynamic Voltage Restorer (DVR is a custom power device utilized to counteract voltage sags. It injects controlled three-phase ac voltages in series with the supply voltage, subsequent to voltage sag, to enhance voltage quality by adjusting the voltage magnitude, wave shape, and phase angle. The DVR is conventionally bypassed during a downstream fault to prevent potential adverse impacts on the fault and to protect the DVR components against the fault current. This paper proposes an augmented control strategy for the DVR that provides:1 voltage-sag compensation under balanced and unbalanced conditions and 2 a fault current interruption (FCI function. This paper introduces and evaluates an auxiliary control strategy for downstream fault current interruption in a radial distribution line by means of a dynamic voltage restorer (DVR. The proposed controller supplements the voltage-sag compensation control of the DVR. It does not require phaselocked loop and independently controls the magnitude and phase angle of the injected voltage for each phase. Fast least error squares digital filters are used to estimate the magnitude and phase of the measured voltages and effectively reduce the impacts of noise, harmonics, and disturbances on the estimated phasor parameters, and this enables effective fault current interrupting even under arcing fault conditions. The performance of the DVR for fault current interruption is analyzed by using MATLAB/SIMULINK software.

  15. Analysis of Planar E+I and ER+I Transformers for Low-Voltage High-Current DC/DC Converters with Focus on Winding Losses and Leakage Inductance

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Zhang, Zhe; Ouyang, Ziwei

    2012-01-01

    In this paper an analysis of two planar transformers designed for high-current switching applications is presented. Typical converter application is represented by fuel and electrolyser cell converters. The transformer designs are based on E+I and ER+I planar cores while the analysis focuses...... on winding resistance and leakage inductances which represent the main concerns related to low-voltage high-current applications. The PCB winding design has a one to one turn ratio with no interleaving between primary and secondary windings. The main goal was to determine if ER planar core could provide...... a significant advantage in terms of winding losses compared to planar E cores. Results from finite element analysis highlight that low frequency winding resistance is lower for the ER core since it is dominated by the lower mean turn length however, as the AC-resistance becomes dominating the winding eddy...

  16. Electromigration early resistance increase measurements

    OpenAIRE

    Niehof, J; Flinn, P. A.; Maloney, T.J.

    1993-01-01

    An early resistance change measurement set-up, using an AC bridge technique, has been developed, and measurements have been performed. Large sample-to-sample variations occur. The characteristic time for the resistance change curve is shorter for resistance increase (under current stress) than for resistance decay (during recovery).

  17. Single-Phase Direct AC-AC Boost Converter

    Directory of Open Access Journals (Sweden)

    LUCANU, M.

    2014-08-01

    Full Text Available The paper presents a single-phase direct AC-AC boost converter. The circuit of the converter is simple and it has good performances, irrespective of the load nature. The adequate functioning and high performance of the circuit (the efficiency and waveform of the absorbed input current were tested both by simulation and experimentally.

  18. Cascading failures in ac electricity grids

    Science.gov (United States)

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

    2016-09-01

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

  19. Offshore Wind Park Connection to an HVDC Platform, without using an AC Collector Platform

    OpenAIRE

    Ahmad, Haseeb

    2012-01-01

    This thesis investigates the comparison between two different alternating current topologies of an offshore wind farms connection to an offshore high voltage direct current (HVDC) converter platform. The offshore high voltage direct current converter platform converts alternating current into direct current. Two different topologies will be investigated. In the first topology, the offshore wind farms are connected to an HVDC converter platform through offshore AC collector platform. An offsho...

  20. Removal of direct current link harmonic ripple in single-phase voltage source inverter systems using supercapacitors

    OpenAIRE

    Hernandez, Gabriel D.

    2016-01-01

    Approved for public release; distribution is unlimited For an Energy Management System (EMS)-controlled microgrid that uses a single-phase voltage source inverter (VSI) configuration to supply power for AC loads from DC energy storage devices, the DC link connecting the VSI to the DC energy storage devices experiences a voltage ripple that is a second-order harmonic of the AC frequency. When the EMS has a battery bank as the only DC energy storage device, the DC link voltage ripple causes ...