WorldWideScience

Sample records for voltage operating level

  1. A High-Voltage Level Tolerant Transistor Circuit

    NARCIS (Netherlands)

    Annema, Anne Johan; Geelen, Godefridus Johannes Gertrudis Maria

    2001-01-01

    A high-voltage level tolerant transistor circuit, comprising a plurality of cascoded transistors, including a first transistor (T1) operatively connected to a high-voltage level node (3) and a second transistor (T2) operatively connected to a low-voltage level node (2). The first transistor (T1) con

  2. Experimental Operation of SSC RF Cavities at Higher Voltage

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    For many years,SSC RF cavities were operated at about half of its designing voltages,which are from 100 kV at 6.5 MHz to 250 kV at 14.5 MHz respectively.But,with the construction of new project HIRFL-CSR,high intensity beams are required to be extracted from SSC.Therefore,in order to achieve this aim,SSC Dee voltages must be enhanced to higher operation level.

  3. Autonomous Operation of Low Voltage Microgrids

    Directory of Open Access Journals (Sweden)

    Irena Wasiak

    2014-12-01

    Full Text Available The article describes the possibilities of LV microgrids operation in the island mode. Control strategies of energy sources connected to the grid by means of invertors are discussed, either for a microgrid connected to the supplying network or during the island mode operation. The presented results of research were conducted at the Laboratory of Distributed Generation at Lodz University of Technology. The study was performed for two variants of reference voltage source: the battery storage and microturbine respectively.

  4. Low voltage operation of plasma focus.

    Science.gov (United States)

    Shukla, Rohit; Sharma, S K; Banerjee, P; Das, R; Deb, P; Prabahar, T; Das, B K; Adhikary, B; Shyam, A

    2010-08-01

    Plasma foci of compact sizes and operating with low energies (from tens of joules to few hundred joules) have found application in recent years and have attracted plasma-physics scientists and engineers for research in this direction. We are presenting a low energy and miniature plasma focus which operates from a capacitor bank of 8.4 muF capacity, charged at 4.2-4.3 kV and delivering approximately 52 kA peak current at approximately 60 nH calculated circuit inductance. The total circuit inductance includes the plasma focus inductance. The reported plasma focus operates at the lowest voltage among all reported plasma foci so far. Moreover the cost of capacitor bank used for plasma focus is nearly 20 U.S. dollars making it very cheap. At low voltage operation of plasma focus, the initial breakdown mechanism becomes important for operation of plasma focus. The quartz glass tube is used as insulator and breakdown initiation is done on its surface. The total energy of the plasma focus is approximately 75 J. The plasma focus system is made compact and the switching of capacitor bank energy is done by manual operating switch. The focus is operated with hydrogen and deuterium filled at 1-2 mbar.

  5. 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.

  6. Impact of Solar Array Designs on High Voltage Operations

    Science.gov (United States)

    Brandhorst, Henry W., Jr.; Ferguson, Dale; Piszczor, Mike; ONeill, Mark

    2006-01-01

    As power levels of advanced spacecraft climb above 25 kW, higher solar array operating voltages become attractive. Even in today s satellites, operating spacecraft buses at 100 V and above has led to arcing in GEO communications satellites, so the issue of spacecraft charging and solar array arcing remains a design problem. In addition, micrometeoroid impacts on all of these arrays can also lead to arcing if the spacecraft is at an elevated potential. For example, tests on space station hardware disclosed arcing at 75V on anodized A1 structures that were struck with hypervelocity particles in Low Earth Orbit (LEO) plasmas. Thus an understanding of these effects is necessary to design reliable high voltage solar arrays of the future, especially in light of the Vision for Space Exploration of NASA. In the future, large GEO communication satellites, lunar bases, solar electric propulsion missions, high power communication systems around Mars can lead to power levels well above 100 kW. As noted above, it will be essential to increase operating voltages of the solar arrays well above 80 V to keep the mass of cabling needed to carry the high currents to an acceptable level. Thus, the purpose of this paper is to discuss various solar array approaches, to discuss the results of testing them at high voltages, in the presence of simulated space plasma and under hypervelocity impact. Three different types of arrays will be considered. One will be a planar array using thin film cells, the second will use planar single or multijunction cells and the last will use the Stretched Lens Array (SLA - 8-fold concentration). Each of these has different approaches for protection from the space environment. The thin film cell based arrays have minimal covering due to their inherent radiation tolerance, conventional GaAs and multijunction cells have the traditional cerium-doped microsheet glasses (of appropriate thickness) that are usually attached with Dow Corning DC 93-500 silicone

  7. Wide Operating Voltage Range Fuel Cell Battery Charger

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Mira Albert, Maria del Carmen; Sen, Gokhan;

    2014-01-01

    DC-DC converters for fuel cell applications require wide voltage range operation due to the unique fuel cell characteristic curve. Primary parallel isolated boost converter (PPIBC) is a boost derived topology for low voltage high current applications reaching an efficiency figure up to 98.2 %. Th...

  8. Wide Operating Voltage Range Fuel Cell Battery Charger

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Mira Albert, Maria del Carmen; Sen, Gokhan

    2014-01-01

    DC-DC converters for fuel cell applications require wide voltage range operation due to the unique fuel cell characteristic curve. Primary parallel isolated boost converter (PPIBC) is a boost derived topology for low voltage high current applications reaching an efficiency figure up to 98.2 %. Th...

  9. Empirical Verification of Fault Models for FPGAs Operating in the Subcritical Voltage Region

    DEFF Research Database (Denmark)

    Birklykke, Alex Aaen; Koch, Peter; Prasad, Ramjee

    2013-01-01

    We present a rigorous empirical study of the bit-level error behavior of field programmable gate arrays operating in the subcricital voltage region. This region is of significant interest as voltage-scaling under normal circumstances is halted by the first occurrence of errors. However, accurate...

  10. A new Zero Voltage Switching three-level NPC inverter

    DEFF Research Database (Denmark)

    He, Ning; Chen, Yenan; Xu, Dehong

    2015-01-01

    A novel Zero Voltage Switching (ZVS) three-level NPC inverter topology using a new ZVS Space Vector Modulation (SVM) scheme is proposed. A detailed operation analysis of ZVS three-level NPC inverter is given. The ZVS condition of the proposed ZVS inverter is derived and it can be achieved of all...... switches in the proposed inverter, which include both the main switches and the auxiliary switches. The design of resonant circuits parameters is also provided. Finally the proposed circuit and ZVS SVM scheme are verified by experimental results and demonstrate a superior performance....

  11. An interleaved five-level boost converter with voltage-balance control

    DEFF Research Database (Denmark)

    Chen, Jianfei; Hou, Shiying; Deng, Fujin

    2016-01-01

    This paper proposes an interleaved five-level boost converter based on switched-capacitor network. Operating principle of the converter under CCM mode is analyzed. High voltage gain, low component stress, small input current ripple, and self-balance function for capacitor voltages in the switched......-capacitor networks are achieved. Besides, a three-loop control strategy including outer voltage loop, inner current loop and voltage-balance loop has been researched to achieve good performances and voltage-balance effect. Experimental study has been done to verify the correctness and feasibility of the proposed...... converter and control strategy....

  12. A dynamic voltage restorer (DVR) with selective harmonic compensation at medium voltage level

    DEFF Research Database (Denmark)

    Newman, M.J.; Holmes, D.G.; Nielsen, J.G.;

    2005-01-01

    -state power through the DVR, the increased losses, and the low modulation depths at which the scheme must operate to achieve acceptable harmonic compensation performance. This paper presents a selective harmonic feedback control strategy that can be easily added to medium-voltage DVR systems to provide...... be advantageous if the series-connected inverter of a DVR could also be used to compensate for any steady-state load voltage harmonics, since this would increase the power quality "value-added" benefits to the grid system. However, before this can be done, consideration must be given to the control of steady...... voltage harmonic compensation capabilities with minimal effect on the sag compensation performance of the basic DVR. The proposed controller has been experimentally verified on a medium-voltage (10 kV) three-phase DVR prototype under a range of conditions, including distorted supply voltages, nonlinear...

  13. Voltage Collapse Risk Associated to Under-Voltage Capacitive Compensation in Electric Power System Operation

    Directory of Open Access Journals (Sweden)

    Heraldo S. Barbuy

    2009-01-01

    Full Text Available Problem statement: In the operation of an Electric Power System (EPS, it has been usual to provide reactive power injection to avoid an under-voltage bus condition. In some situations an adequate voltage profile will not be a guarantee against Voltage Collapses (VCs that may cause blackouts as seen in many occurrences around the world. The repeatedly injection of reactive power can turn a bus into a characteristic too much capacitive. Under this condition and in the presence of a considerable percentage of the constant power load type, there will be a high risk of a VC. Any of the indices proposed in the literature as VC Proximity Indicators (VCPIs may alert the operator about the risk. Approach: In order to elucidate the problem stated, simulations were performed using MatLab/SimPowerSystems. It was used a basic example system composed by an infinite-bus feeding, through a large impedance line, a bus load whose power could be increased in ramp manner. It is also included a shunt capacitive compensation at the load bus every time the voltage value reaches 0.9 pu. Therefore, the VC risk increase could be shown by means of graphic results and the indications of some VCPIs sensitivity indices (including the new proposed index. Results: The graphics obtained in this study is a contribution to illustrate the voltage collapse risk problem when dealing with adjustments of voltage profile to meet the system requirements. Also, a VCPI sensitivity indicator using apparent load power was tested. The results have shown that all VCPI responses are very similar for a given case and electric system. Conclusion/Recommendations: Any VCPI information can help in the decision stage between either more reactive power injection or load shedding. A routine can also be developed for a supervisory program in order to alert the operator about VC risks.

  14. Primary Paralleled Isolated Boost Converter with Extended Operating Voltage Range

    DEFF Research Database (Denmark)

    Hernandez Botella, Juan Carlos; Sen, Gökhan; Mira Albert, Maria del Carmen

    2012-01-01

    Applications requiring wide input and output voltage range cannot often be satisfied by using buck or boost derived topologies. Primary paralleled isolated boost converter (PPIBC) [1]-[2] is a high efficiency boost derived topology. This paper proposes a new operation mode for extending the input...

  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. A study on threshold voltage stability of low operating voltage organic thin-film transistors

    Science.gov (United States)

    Padma, N.; Sen, Shaswati; Sawant, Shilpa N.; Tokas, R.

    2013-08-01

    A low operating voltage (<2 V) organic field-effect transistor (OFET) using phenylhexyltrichlorosilane (PTS) self-assembled monolayer (SAM) dielectric and copper phthalocyanine (CuPc) as semiconductor with improved mobility (0.035 cm2 V-1 s-1) and threshold voltage stability was demonstrated. This device showed better performance when compared to an OFET with octyltrichlorosilane (OTS-8) SAM dielectric. The improved mobility was attributed to the 2D growth mode of CuPc on PTS SAM because of surface energy matching between the two, whereas CuPc film on OTS-8 showed a 3D growth mode with larger grain boundary density. The higher threshold voltage stability of OFETs on PTS SAM was attributed to the efficient coverage and screening of trap centres at dielectric/semiconductor interface due to stronger intermolecular linking and formation of closely packed surface by the bulky phenyl end groups. Decrease in grain boundaries offered by 2D growth of CuPc for electron and hole trapping was also found to be another reason for improved threshold voltage stability. The results indicated that the nature of the end group of SAM dielectric, surface chemistry of dielectric and initial growth mode of semiconductors are all responsible for improvement in threshold voltage stability and enhanced performance of OFET.

  17. Assessment of the operating conditions of coordinated Q-V controller within secondary voltage control system

    Directory of Open Access Journals (Sweden)

    Arnautović Dušan

    2014-01-01

    Full Text Available The paper, discusses the possibility to use coordinated Q-V controller (CQVC to perform secondary voltage control at the power plant level. The CQVC performs the coordination of the synchronous generators' (SG reactive power outputs in order to maintain the same total reactive power delivered by the steam power plant (SPP, while at the same time maintaining a constant voltage with programmed reactive droop characteristic at the SPP HV busbar. This busbar is the natural pilot node for secondary voltage control at HV level as the node with maximum power production and maximum power consumption. In addition to voltage control, the CQVC maintains the uniform allocation of reactive power reserves at all SGs in the power plant. This is accomplished by setting the reactive power of each SG at given operating point in accordance to the available reactive power of the same SG at that point. Different limitations imposed by unit's and plant equipment are superimposed on original SG operating chart (provided by the manufacturer in order to establish realistic limits of SG operation at given operating point. The CQVC facilitates: i practical implementation of secondary voltage control in power system, as it is capable of ensuring delivery of reactive power as requested by regional/voltage control while maintaining voltage at system pilot node, ii the full deployment of available reactive power of SGs which in turn contributes to system stability, iii assessment of the reactive power impact/contribution of each generator in providing voltage control as ancillary service. Furthermore, it is also possible to use CQVC to pricing reactive power production cost at each SG involved and to design reactive power bidding structure for transmission network devices by using recorded data. Practical exploitation experience acquired during CQVC continuous operation for over two years enabled implementation of the optimal setting of reference voltage and droop on daily

  18. Voltage Balancing Method on Expert System for 51-Level MMC in High Voltage Direct Current Transmission

    Directory of Open Access Journals (Sweden)

    Yong Chen

    2016-01-01

    Full Text Available The Modular Multilevel Converters (MMC have been a spotlight for the high voltage and high power transmission systems. In the VSC-HVDC (High Voltage Direct Current based on Voltage Source Converter transmission system, the energy of DC link is stored in the distributed capacitors, and the difference of capacitors in parameters and charge rates causes capacitor voltage balance which affects the safety and stability of HVDC system. A method of MMC based on the expert system for reducing the frequency of the submodules (SMs of the IGBT switching frequency is proposed. Firstly, MMC with 51 levels for HVDC is designed. Secondly, the nearest level control (NLC for 51-level MMC is introduced. Thirdly, a modified capacitor voltage balancing method based on expert system for MMC-based HVDC transmission system is proposed. Finally, a simulation platform for 51-level Modular Multilevel Converter is constructed by using MATLAB/SIMULINK. The results indicate that the strategy proposed reduces the switching frequency on the premise of keeping submodule voltage basically identical, which greatly reduces the power losses for MMC-HVDC system.

  19. 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.

  20. To Implement Energy Efficient of Integer Unit by Higher Voltage Flip Flop Based on Minimum operating Dual Supply Voltage Techinque

    Directory of Open Access Journals (Sweden)

    M. Subhashini,

    2014-06-01

    Full Text Available To achieve the most energy-efficient operation, this brief presents a circuit design technique for separating the power supply voltage (VDD of flip-flops (FFs from that of combinational circuits, called the higher voltage FF (HVFF. Although VDD scaling can reduce the energy, the minimum operating voltage (VDDmin of FFs prevents the operation at the optimum supply voltage that minimizes the energy, because the VDDmin of FFs is higher than the optimum supply voltage. In HVFF, the VDD of combinational logic gates is reduced below the VDDmin of FFs while keeping the VDD of FFs at their VDDmin. This makes it possible to minimize the energy without power and delay penalties at the nominal supply voltage (1.2 V as well as without FF topological difications. A four bit alu is designed in these paper by using dual supply voltage usig DSCH.

  1. Low-voltage CMOS operational amplifiers theory, design and implementation

    CERN Document Server

    Sakurai, Satoshi

    1995-01-01

    Low-Voltage CMOS Operational Amplifiers: Theory, Design and Implementation discusses both single and two-stage architectures. Opamps with constant-gm input stage are designed and their excellent performance over the rail-to-rail input common mode range is demonstrated. The first set of CMOS constant-gm input stages was introduced by a group from Technische Universiteit, Delft and Universiteit Twente, the Netherlands. These earlier versions of circuits are discussed, along with new circuits developed at the Ohio State University. The design, fabrication (MOSIS Tiny Chips), and characterization of the new circuits are now complete. Basic analog integrated circuit design concepts should be understood in order to fully appreciate the work presented. However, the topics are presented in a logical order and the circuits are explained in great detail, so that Low-Voltage CMOS Operational Amplifiers can be read and enjoyed by those without much experience in analog circuit design. It is an invaluable reference boo...

  2. Method for reducing fuel cell output voltage to permit low power operation

    Science.gov (United States)

    Reiser, Carl A.; Landau, Michael B.

    1980-01-01

    Fuel cell performance is degraded by recycling a portion of the cathode exhaust through the cells and, if necessary, also reducing the total air flow to the cells for the purpose of permitting operation below a power level which would otherwise result in excessive voltage.

  3. Design of low-voltage bipolar operational amplifiers

    Science.gov (United States)

    Fonderie, Jeroen

    The design of input stages for low voltage Operational Amplifiers (OpAmps) is considered. The purpose of this design emanates from the objective of having a common mode input voltage range that reaches from one supply rail to the other, and designs that have this feature both at a 2 V and at a 1 V supply are discussed. Possible output stage configurations are analyzed. This discussion is restricted to output stages that have an output voltage range that also reaches from rail to rail. Further, the output stage should be able to supply a sufficiently large output current to the load that is externally connected to the OpAmp. The frequency response of the output stage is the focus of the discussion. The circuit parts that remain to complete the design of the OpAmp are discussed. These circuit parts are the intermediate stage, inserted between the input and output stage to boost the overall gain of the OpAmp, some implementations of the class AB current control circuit, circuitry to protect the output transistor from heavy saturation and from excessive power consumption, and, finally, the proportional to absolute temperature reference current generator. A detailed analysis of the frequency compensation techniques that can be used to stabilize the OpAmp is given. From this theory, design criteria to successfully implement the compensation method are derived. The experimental OpAmp designs and the measurements performed on these designs are described. Conclusions and suggestions for further research are given.

  4. High Voltage Operation of heavily irradiated silicon microstrip detectors

    CERN Document Server

    Gu, W H; Angarano, M M; Bader, A; Biggeri, U; Boemi, D; Braibant, S; Breuker, H; Bruzzi, Mara; Caner, A; Catacchini, E; Civinini, C; Creanza, D; D'Alessandro, R; Demaria, N; Eklund, C; Peisert, Anna; Feld, L; Fiore, L; Focardi, E; Fürtjes, A; Glessing, B; Hall, G; Hammerstrom, R; Dollan, Ralph; Huhtinen, M; Karimäki, V; König, S; Lenzi, M; Lübelsmeyer, K; Maggi, G; Mannelli, M; Marchioro, A; Mariotti, C; Mättig, P; McEvoy, B; Meschini, M; My, S; Pandoulas, D; Parrini, G; Pieri, M; Dollan, Ralph; Potenza, R; Raso, G; Raymond, M; Schmitt, B; Selvaggi, G; Siedling, R; Silvestris, L; Skog, K; Stefanini, G; Tempesta, P; Tricomi, A; Watts, S; Wittmer, B; De Palma, M

    1999-01-01

    We discuss the results obtained from the R&D studies, done within the CMS experiment at LHC related to the behaviour of silicon microstrip prototype detectors when they are operated at high bias voltages before and after heavy irradiation, simulating up to 10 years of LHC running conditions. We have found detectors from several manufacturesrs that are able to work at V_bias > 500 Volts before and after the irradiation procedure, maintaining an acceptable performance with S/N > 14, efficiency close to 100% and few ghost hits.

  5. 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...

  6. Loading Analysis of Modular Multi-level Converter for Offshore High-voltage DC Application under Various Grid Faults

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Loh, Poh Chiang;

    2016-01-01

    The modular multi-level converter has become an interesting candidate in high-voltage DC systems due to its higher voltage levels and modular construction. Low-voltage ride-through is an important grid requirement for modular multi-level converter–high-voltage DC since not only causes control...... challenges but may also result in overstressed components for the modular multi-level converter. However, the thermal loading of the modular multi-level converter under various grid faults has not yet been clarified. In this article, the power loss and thermal performance of the modular multi-level converter...... during grid voltage dips are studied. The impacts of two typical grid faults to the modular multi-level converter in terms of operating and loading conditions are analytically researched and simulated. It has been found that the operating and loading conditions of the modular multi-level converter under...

  7. Operating Experiences of a Loss of Voltage Monitoring Program

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Eun-Chan [Korea Hydro and Nuclear Power Co. Ltd., Daejeon (Korea, Republic of)

    2015-10-15

    Loss of voltage (LOV) events continue to occur due to inadequate work management and random human errors. On February 26, 2015, regulators analyzed the root causes of LOV events and presented the results for the nuclear industry. Currently, KHNP uses a risk monitoring program, which is named 'LOV Monitor', for LOV prevention during pilot plant outages. This review introduces the operation experiences of LOV Monitor based on the evaluation results of a real event. The operation experiences of LOV Monitor in the pilot plants confirmed that this program could detect and reduce LOV possibilities from scheduling errors such as the simultaneous maintenance of energized trains and de-energized trains considering the physical conditions of the power circuit breakers. However, a maintenance culture that heeds the risk monitoring result must be strengthened in order to obtain substantial effects through applying LOV Monitor to the outage.

  8. High-Voltage-Input Level Translator Using Standard CMOS

    Science.gov (United States)

    Yager, Jeremy A.; Mojarradi, Mohammad M.; Vo, Tuan A.; Blalock, Benjamin J.

    2011-01-01

    proposed integrated circuit would translate (1) a pair of input signals having a low differential potential and a possibly high common-mode potential into (2) a pair of output signals having the same low differential potential and a low common-mode potential. As used here, "low" and "high" refer to potentials that are, respectively, below or above the nominal supply potential (3.3 V) at which standard complementary metal oxide/semiconductor (CMOS) integrated circuits are designed to operate. The input common-mode potential could lie between 0 and 10 V; the output common-mode potential would be 2 V. This translation would make it possible to process the pair of signals by use of standard 3.3-V CMOS analog and/or mixed-signal (analog and digital) circuitry on the same integrated-circuit chip. A schematic of the circuit is shown in the figure. Standard 3.3-V CMOS circuitry cannot withstand input potentials greater than about 4 V. However, there are many applications that involve low-differential-potential, high-common-mode-potential input signal pairs and in which standard 3.3-V CMOS circuitry, which is relatively inexpensive, would be the most appropriate circuitry for performing other functions on the integrated-circuit chip that handles the high-potential input signals. Thus, there is a need to combine high-voltage input circuitry with standard low-voltage CMOS circuitry on the same integrated-circuit chip. The proposed circuit would satisfy this need. In the proposed circuit, the input signals would be coupled into both a level-shifting pair and a common-mode-sensing pair of CMOS transistors. The output of the level-shifting pair would be fed as input to a differential pair of transistors. The resulting differential current output would pass through six standoff transistors to be mirrored into an output branch by four heterojunction bipolar transistors. The mirrored differential current would be converted back to potential by a pair of diode-connected transistors

  9. 30 CFR 57.12071 - Movement or operation of equipment near high-voltage powerlines.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Movement or operation of equipment near high-voltage powerlines. 57.12071 Section 57.12071 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...-voltage powerlines. When equipment must be moved or operated near energized high-voltage powerlines...

  10. 30 CFR 56.12071 - Movement or operation of equipment near high-voltage power lines.

    Science.gov (United States)

    2010-07-01

    ...-voltage power lines. 56.12071 Section 56.12071 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... NONMETAL MINES Electricity § 56.12071 Movement or operation of equipment near high-voltage power lines. When equipment must be moved or operated near energized high-voltage powerlines (other than...

  11. A wiggler magnet for FEL low voltage operation

    Energy Technology Data Exchange (ETDEWEB)

    Al-Shamma`a, A.; Stuart, R.A.; Lucas, J.

    1995-12-31

    In low voltage FELs (ie, 200kV), operation is necessarily in the microwave frequency range for wiggler periods of the order of cms., so that a waveguide system is mandatory. Also, because of the relatively low velocity of the electron beam, the wiggle amplitude of the electron beam can be much larger than is normal for highly relativistic FELs. Both these factors mean that the electron trajectory must be carefully controlled to avoid beam collision with the waveguide walls. A wiggler system with half poles at entrance and exit is not an acceptable solution because of the offset is gives rise to the electron trajectory. Consequently, we have designed and constructed a wiggler magnet with exponential entrance and exit tapers for a minimal deflection and displacement of the electron beam. Simulations and experimental measurements showed that an on axis trajectory is easily obtainable.

  12. Design of a high frequency low voltage CMOS operational amplifier

    Directory of Open Access Journals (Sweden)

    Priyanka Kakoty

    2011-03-01

    Full Text Available A method is presented in this paper for the design of a high frequency CMOS operational amplifier (Op-Amp which operates at 3V power supply using tsmc 0.18 micron CMOS technology. The OPAMPdesigned is a two-stage CMOS OPAMP followed by an output buffer. This Operational Transconductance Amplifier (OTA employs a Miller capacitor and is compensated with a current buffer compensation technique. The unique behaviour of the MOS transistors in saturation region not only allows a designer to work at a low voltage, but also at a high frequency. Designing of two-stage op-ampsis a multi-dimensional-optimization problem where optimization of one or more parameters may easily result into degradation of others. The OPAMP is designed to exhibit a unity gain frequency of 2.02GHzand exhibits a gain of 49.02dB with a 60.50 phase margin. As compared to the conventional approach, the proposed compensation method results in a higher unity gain frequency under the same load condition.Design has been carried out in Tanner tools. Simulation results are verified using S-edit and W-edit.

  13. Design of a high frequency low voltage CMOS operational amplifier

    Directory of Open Access Journals (Sweden)

    Priyanka Kakoty

    2011-03-01

    Full Text Available A method is presented in this paper for the design of a high frequency CMOS operational amplifier (Op-Amp which operates at 3V power supply using tsmc 0.18 micron CMOS technology. The OPAMPdesigned is a two-stage CMOS OPAMP followed by an output buffer. This OperationalTransconductance Amplifier (OTA employs a Miller capacitor and is compensated with a current buffercompensation technique. The unique behaviour of the MOS transistors in saturation region not onlyallows a designer to work at a low voltage, but also at a high frequency. Designing of two-stage op-ampsis a multi-dimensional-optimization problem where optimization of one or more parameters may easilyresult into degradation of others. The OPAMP is designed to exhibit a unity gain frequency of 2.02GHzand exhibits a gain of 49.02dB with a 60.50 phase margin. As compared to the conventional approach, theproposed compensation method results in a higher unity gain frequency under the same load condition.Design has been carried out in Tanner tools. Simulation results are verified using S-edit and W-edit.

  14. 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.

  15. ELABORATION OF HIGH-VOLTAGE PULSE INSTALLATIONS AND PROVIDING THEIR OPERATION PROTECTIVE MEASURES

    Directory of Open Access Journals (Sweden)

    А. М. Hashimov

    2016-01-01

    Full Text Available The article presents design engineering methods for the high-voltage pulse installations of technological purpose for disinfection of drinking water, sewage, and edible liquids by high field micro- and nanosecond pulsing exposure. Designing potentialities are considered of the principal elements of the high-voltage part and the discharge circuit of the installations towards assuring the best efficient on-load utilization of the source energy and safe operation of the high-voltage equipment. The study shows that for disinfection of drinking water and sewage it is expedient to apply microsecond pulse actions causing the electrohydraulic effect in aqueous media with associated complex of physical processes (ultraviolet emission, generation of ozone and atomic oxygen, mechanical compression waves, etc. having detrimental effect on life activity of the microorganisms. In case of disinfecting edible liquids it is recommended to use the nanosecond pulses capable of straight permeating the biological cell nucleus, inactivating it. Meanwhile, the nutritive and biological values of the foodstuffs are saved and their organoleptic properties are improved. It is noted that in elaboration process of high-frequency pulse installations special consideration should be given to issues of the operating personnel safety discipline and securing conditions for the entire installation uninterrupted performance. With this objective in view the necessary requirements should be fulfilled on shielding the high- and low-voltage installation parts against high-frequency electromagnetic emissions registered by special differential sensors. Simultaneously, the abatement measures should be applied on the high-voltage equipment operational noise level. The authors offer a technique for noise abatement to admissible levels (lower than 80 dB A by means of coating the inside surface with shielded enclosure of densely-packed abutting sheets of porous electro-acoustic insulating

  16. Specifics of operation of a cold-cathode thyratron with a backward voltage half-wave

    Science.gov (United States)

    Korolev, Yu. D.; Landl, N. V.; Geiman, V. G.; Frants, O. B.; Bolotov, A. V.; Nekhoroshev, V. O.; Kasyanov, V. S.

    2017-05-01

    The specifics of operating a metal-ceramic TPI1-10k/50 thyratron in electric circuits with capacitance, inductance, and active resistance have been examined under circuit parameters that establish oscillatory current. Experiments have been performed at an anode voltage as high as 30 kV, a forward current of up to 7.6 kA, and a length of the first current half-period that varies from 0.38 to 1.9 μs. The data on operating modes in which this thyratron may handle a backward current wave and when current interruption is observed in the second half-period have been obtained. It has been demonstrated that a certain current flows through the thyratron in the backward direction during the interruption process. The amplitude of this current and the maximum backward voltage at the thyratron define whether the current is interrupted or repeat back-voltage device breakdown occurs. If the maximum backward current is on the level of several hundred amperes, complete current interruption occurs at backward voltages of up to 12 kV. The physical mechanisms of current interruption have been discussed.

  17. Wide Operational Range Processor Power Delivery Design for Both Super-Threshold Voltage and Near-Threshold Voltage Computing

    Institute of Scientific and Technical Information of China (English)

    Xin He; Gui-Hai Yan; Yin-He Han; Xiao-Wei Li

    2016-01-01

    The load power range of modern processors is greatly enlarged because many advanced power management techniques are employed, such as dynamic voltage frequency scaling, Turbo Boosting, and near-threshold voltage (NTV) technologies. However, because the efficiency of power delivery varies greatly with different load conditions, conventional power delivery designs cannot maintain high efficiency over the entire voltage spectrum, and the gained power saving may be offset by power loss in power delivery. We propose SuperRange, a wide operational range power delivery unit. SuperRange complements the power delivery capability of on-chip voltage regulator and off-chip voltage regulator. On top of SuperRange, we analyze its power conversion characteristics and propose a voltage regulator (VR) aware power management algorithm. Moreover, as more and more cores have been integrated on a singe chip, multiple SuperRange units can serve as basic building blocks to build, in a highly scalable way, more powerful power delivery subsystem with larger power capacity. Experimental results show SuperRange unit offers 1x and 1.3x higher power conversion efficiency (PCE) than other two conventional power delivery schemes at NTV region and exhibits an average 70%PCE over entire operational range. It also exhibits superior resilience to power-constrained systems.

  18. Choice of operating voltage for a transmission electron microscope

    Energy Technology Data Exchange (ETDEWEB)

    Egerton, R.F., E-mail: regerton@ualberta.ca

    2014-10-15

    An accelerating voltage of 100–300 kV remains a good choice for the majority of TEM or STEM specimens, avoiding the expense of high-voltage microscopy but providing the possibility of atomic resolution even in the absence of lens-aberration correction. For specimens thicker than a few tens of nm, the image intensity and scattering contrast are likely to be higher than at lower voltage, as is the visibility of ionization edges below 1000 eV (as required for EELS elemental analysis). In thick (>100 nm) specimens, higher voltage ensures less beam broadening and better spatial resolution for STEM imaging and EDX spectroscopy. Low-voltage (e.g. 30 kV) TEM or STEM is attractive for a very thin (e.g. 10 nm) specimen, as it provides higher scattering contrast and fewer problems for valence-excitation EELS. Specimens that are immune to radiolysis suffer knock-on damage at high current densities, and this form of radiation damage can be reduced or avoided by choosing a low accelerating voltage. Low-voltage STEM with an aberration-corrected objective lens (together with a high-angle dark-field detector and/or EELS) offers atomic resolution and elemental identification from very thin specimens. Conventional TEM can provide atomic resolution in low-voltage phase-contrast images but requires correction of chromatic aberration and preferably an electron-beam monochromator. Many non-conducting (e.g. organic) specimens damage easily by radiolysis and radiation damage then determines the TEM image resolution. For bright-field scattering contrast, low kV can provide slightly better dose-limited resolution if the specimen is very thin (a few nm) but considerably better resolution is possible from a thicker specimen, for which higher kV is required. Use of a phase plate in a conventional TEM offers the most dose-efficient way of achieving atomic resolution from beam-sensitive specimens. - Highlights: • 100–300 kV accelerating voltage is suitable for TEM specimens of typical

  19. Grid Integration of Single Stage Solar PV System using Three-level Voltage Source Converter

    Science.gov (United States)

    Hussain, Ikhlaq; Kandpal, Maulik; Singh, Bhim

    2016-08-01

    This paper presents a single stage solar PV (photovoltaic) grid integrated power generating system using a three level voltage source converter (VSC) operating at low switching frequency of 900 Hz with robust synchronizing phase locked loop (RS-PLL) based control algorithm. To track the maximum power from solar PV array, an incremental conductance algorithm is used and this maximum power is fed to the grid via three-level VSC. The use of single stage system with three level VSC offers the advantage of low switching losses and the operation at high voltages and high power which results in enhancement of power quality in the proposed system. Simulated results validate the design and control algorithm under steady state and dynamic conditions.

  20. Reduction of Voltage Harmonics for Parallel-operated Inverters

    DEFF Research Database (Denmark)

    Zhong, Qing-Chang; Blaabjerg, Frede; Guerrero, Josep M.

    2011-01-01

    The inherent limitations of the conventional droop control scheme have recently been revealed and a robust droop controller to achieve exact proportional load sharing has been proposed. This paper continues the work with a strategy to improve the voltage quality so that the total harmonic...... distortion of the output voltage can be maintained small even when nonlinear loads are connected. Experimental results are provided to verify the analysis and design....

  1. High Voltage Breakdown Levels in Various EPC Potting Materials

    Science.gov (United States)

    Komm, David S.

    2006-01-01

    This viewgraph presentation reviews exploration activities at JPL into various potting materials. Since high power space-borne microwave transmitters invariably use a vacuum tube as a final power amplifier, and this tube requires high electrode voltages for operation. The associated high voltage insulation typically represents a significant fraction of the mass of the transmitter. Since mass is always a premium resource on board spacecraft, we have been investigating materials with the potential to reduce the mass required for our applications here at JPL. This paper describes electrical breakdown results obtained with various potting materials. Conathane EN-11 (polyurethane) is the traditional HVPS encapsulant at JPL, but due to temperature limitations and durability issues it was deemed inappropriate for the particular application (i.e., CloudSat radar). The choices for the best available materials were epoxies, or silicones. Epoxies are too rigid, and were deemed inadvisable. Two silicones were further investigated (i.e.,ASTM E595- 93e2: GE RTV566(R) and Dow Corning 93-500X(R), another compound was considered (i.e., DC material, Sylgard 184(R)). "Loading" (adding filler materials) the potting compound will frequently alter the final material properties. Powdered alumina and borosilicate glass known as "microballoons" were investigated as possible loading materials. The testing of the materials is described. Each of the two loading materials offers advantages and disadvantages. The advantages and disadvantages are described.

  2. High Voltage Operation of Helical Pulseline Structures for Ion Acceleration

    CERN Document Server

    Waldron, William; Reginato, Lou

    2005-01-01

    The basic concept for the acceleration of heavy ions using a helical pulseline requires the launching of a high voltage traveling wave with a waveform determined by the beam transport physics in order to maintain stability and acceleration.* This waveform is applied to the front of the helix, creating over the region of the ion bunch a constant axial acceleration electric field that travels down the line in synchronism with the ions. Several methods of driving the helix have been considered. Presently, the best method of generating the waveform and also maintaining the high voltage integrity appears to be a transformer primary loosely coupled to the front of the helix, generating the desired waveform and achieving a voltage step-up from primary to secondary (the helix). This can reduce the drive voltage that must be brought into the helix enclosure through the feedthroughs by factors of 5 or more. The accelerating gradient is limited by the voltage holding of the vacuum insulator, and the material and helix g...

  3. Write operation in MRAM with voltage controlled magnetic anisotropy

    Science.gov (United States)

    Munira, Kamaram; Pandey, Sumeet; Sandhu, Gurtej

    In non-volatile Magnetic RAM, information is saved in the bistable configuration of the free layer in a magnetic tunnel junction (MTJ). New information can be written to the free layer through magnetic induction (Toggle MRAM) or manipulation of magnetization using electric currents (Spin Transfer Torque MRAM or STT-MRAM). Both of the writing methods suffer from a shortcoming in terms of energy efficiency. This limitation on energy performance is brought about by the need for driving relatively large electrical charge currents through the devices for switching. In STT-MRAM, the nonzero voltage drop across the resistive MTJ leads to significant power dissipation. An energy efficient way to write may be with the assistance of voltage controlled magnetic anisotropy (VCMA), where voltage applied across the MTJ creates an electric field that modulates the interfacial anisotropy between the insulator and free layer. However, VCMA cannot switch the free layer completely by 180 degree rotation of magnetization. It can lower the barrier between the two stable configurations or at best, cancel the barrier, allowing 90 degree rotation. A second mechanism, spin torque or magnetic field, is needed to direct the final switching destination.

  4. A high-speed CMOS current op amp for very low supply voltage operation

    DEFF Research Database (Denmark)

    Bruun, Erik

    1994-01-01

    A CMOS implementation of a high-gain current mode operational amplifier (op amp) with a single-ended input and a differential output is described. This configuration is the current mode counterpart of the traditional voltage mode op amp. In order to exploit the inherent potential for high speed......, low voltage operation normally associated with current mode analog signal processing, the op amp has been designed to operate off a supply voltage of 1.5 V, and the signal path has been confined to N-channel transistors. With this design, a gain of 94 dB and a gain-bandwidth product of 65 MHz has been...

  5. A quasi-3-dimensional simulation method for a high-voltage level-shifting circuit structure

    Institute of Scientific and Technical Information of China (English)

    Liu Jizhi; Chen Xingbi

    2009-01-01

    A new quasi-three-dimensional (quasi-3D) numeric simulation method for a high-voltage level-shifting circuit structure is proposed. The performances of the 3D structure are analyzed by combining some 2D device structures; the 2D devices are in two planes perpendicular to each other and to the surface of the semiconductor. In comparison with Davinci, the full 3D device simulation tool, the quasi-3D simulation method can give results for the potential and current distribution of the 3D high-voltage level-shifting circuit structure with appropriate accuracy and the total CPU time for simulation is significantly reduced. The quasi-3D simulation technique can be used in many cases with advantages such as saving computing time, making no demands on the high-end computer terminals, and being easy to operate.

  6. A flexible low-voltage ride-through operation for the distributed generation converters

    DEFF Research Database (Denmark)

    Chen, Hsin-Chih; Lee, Chia-Tse; Cheng, Po-Tai;

    2013-01-01

    -sequence current injection method is proposed to meet the low-voltage ride through (LVRT) requirement. The proposed method predefined a current constraint to avoid the overcurrent during the LVRT operation and adjust the positive-sequence reactive current to reduce the DC-bus voltage ripple. Comparisons...

  7. A magnesium–sodium hybrid battery with high operating voltage

    Energy Technology Data Exchange (ETDEWEB)

    Dong, Hui; Li, Yifei; Liang, Yanliang; Li, Guosheng; Sun, Cheng-Jun; Ren, Yang; Lu, Yuhao; Yao, Yan

    2016-06-10

    We report a high performance magnesium-sodium hybrid battery utilizing a magnesium-sodium dual-salt electrolyte, a magnesium anode, and a Berlin green cathode. The cell delivers an average discharge voltage of 2.2 V and a reversible capacity of 143 mAh g-1. We also demonstrate the cell with an energy density of 135 Wh kg-1 and a high power density of up to 1.67 kW kg-1.

  8. Investigation of Voltage Unbalance Problems In Electric Arc Furnace Operation Model

    OpenAIRE

    Yacine DJEGHADER; Hocine LABAR

    2013-01-01

    In modern steel industry, Electric Arc Furnaces are widely used for iron and scarp melting. The operation of electric arc furnace causes many power quality problems such as harmonics, unbalanced voltage and flicker. The factors that affect Electric arc furnace operation are the melting or refining materials, melting stage, electrodes position (arc length), electrode arm control and short circuit power of the feeder, so, arc voltages, current and power are defined as a nonlinear function of ar...

  9. Guidelines for Distribution System Operators on Reactive Power Provision by Electric Vehicles in Low Voltage Grids

    DEFF Research Database (Denmark)

    Zecchino, Antonio; Marinelli, Mattia; Træholt, Chresten

    2017-01-01

    The increasing success of electric vehicles is bringing new technical challenges to power system operators. This work intends to provide guidelines for distribution system operators in terms of reactive power requirements when evaluating and authorizing electric vehicles supply equipment with fast...... the amount of reactive power that an individual electric vehicle is expected to provide when connected to a low voltage feeder, in order to benefit of the desired voltage rise effect in comparison to the case of unitary power factor....

  10. Synchronised Voltage Space Vector Modulation for Three-level Inverters with Common-mode Voltage Elimination

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede

    2002-01-01

    of the voltage waveforms during the whole control range including overmodulation. Continuous, discontinuous and "direct-direct" schemes of synchronous PWM with both algebraic and trigonometric control functions have been analysed and compared. Simulations give the behaviour of the proposed methods and show some...

  11. Investigation of Voltage Unbalance Problems In Electric Arc Furnace Operation Model

    Directory of Open Access Journals (Sweden)

    Yacine DJEGHADER

    2013-06-01

    Full Text Available In modern steel industry, Electric Arc Furnaces are widely used for iron and scarp melting. The operation of electric arc furnace causes many power quality problems such as harmonics, unbalanced voltage and flicker. The factors that affect Electric arc furnace operation are the melting or refining materials, melting stage, electrodes position (arc length, electrode arm control and short circuit power of the feeder, so, arc voltages, current and power are defined as a nonlinear function of arc length. This study focuses on investigation of unbalanced voltage due to Electrics Arc Furnace operation mode. The simulation results show the major problem of unbalanced voltage affecting secondary of furnace transformer is caused by the different continues movement of electrodes.

  12. Incorporating voltage security into the planning, operation and monitoring of restructured electric energy markets

    Science.gov (United States)

    Nair, Nirmal-Kumar

    As open access market principles are applied to power systems, significant changes are happening in their planning, operation and control. In the emerging marketplace, systems are operating under higher loading conditions as markets focus greater attention to operating costs than stability and security margins. Since operating stability is a basic requirement for any power system, there is need for newer tools to ensure stability and security margins being strictly enforced in the competitive marketplace. This dissertation investigates issues associated with incorporating voltage security into the unbundled operating environment of electricity markets. It includes addressing voltage security in the monitoring, operational and planning horizons of restructured power system. This dissertation presents a new decomposition procedure to estimate voltage security usage by transactions. The procedure follows physical law and uses an index that can be monitored knowing the state of the system. The expression derived is based on composite market coordination models that have both PoolCo and OpCo transactions, in a shared stressed transmission grid. Our procedure is able to equitably distinguish the impacts of individual transactions on voltage stability, at load buses, in a simple and fast manner. This dissertation formulates a new voltage stability constrained optimal power flow (VSCOPF) using a simple voltage security index. In modern planning, composite power system reliability analysis that encompasses both adequacy and security issues is being developed. We have illustrated the applicability of our VSCOPF into composite reliability analysis. This dissertation also delves into the various applications of voltage security index. Increasingly, FACT devices are being used in restructured markets to mitigate a variety of operational problems. Their control effects on voltage security would be demonstrated using our VSCOPF procedure. Further, this dissertation investigates

  13. High-Voltage 1-kW dc/dc Converter Developed for Low-Temperature Operation

    Science.gov (United States)

    Patterson, Richard L.

    1998-01-01

    Recently, Lewis developed and demonstrated a high-voltage, 1-kW dc/dc converter that operates from room temperature to -184 C. A power supply designed for use in a NASA ion beam propulsion system was utilized as a starting point for the design of a low- (wide-) temperature dc/dc converter. For safety, we decided to halve the output voltage and power level, so the converter was designed for an 80-Vdc input and a 550-Vdc output at 1 kW.

  14. A novel single phase buck PFC converter in discontinuous capacitor voltage mode operation

    Institute of Scientific and Technical Information of China (English)

    邓超平; 凌志斌; 叶芃生

    2003-01-01

    A novel single-phase Buck converter for power factor correction is proposed. It features simple control due to the constant duty ratio PWM used. It can obtain unity power factor by selecting a suitable LC filter at its input to force the voltage of capacitor to operate in discontinuous capacitor voltage mode. And by using another resonant LC filter at its output, it can not only eliminate the input current distortion at the vicinity of the zero crossing of the supply but also drastically reduce the 100 Hz output voltage ripple. The validity of analysis is confirmed by simulation results and experimental results.

  15. Methods, systems and apparatus for controlling third harmonic voltage when operating a multi-space machine in an overmodulation region

    Energy Technology Data Exchange (ETDEWEB)

    Perisic, Milun; Kinoshita, Michael H; Ranson, Ray M; Gallegos-Lopez, Gabriel

    2014-06-03

    Methods, system and apparatus are provided for controlling third harmonic voltages when operating a multi-phase machine in an overmodulation region. The multi-phase machine can be, for example, a five-phase machine in a vector controlled motor drive system that includes a five-phase PWM controlled inverter module that drives the five-phase machine. Techniques for overmodulating a reference voltage vector are provided. For example, when the reference voltage vector is determined to be within the overmodulation region, an angle of the reference voltage vector can be modified to generate a reference voltage overmodulation control angle, and a magnitude of the reference voltage vector can be modified, based on the reference voltage overmodulation control angle, to generate a modified magnitude of the reference voltage vector. By modifying the reference voltage vector, voltage command signals that control a five-phase inverter module can be optimized to increase output voltages generated by the five-phase inverter module.

  16. Bidirectional Five-Level Power Processing Interface for Low Voltage Battery Energy Storage System

    Science.gov (United States)

    Huang, Jain-Yi; Jou, Hurng-Liahng; Wu, Kuen-Der; Lin, You-Si; Wu, Jinn-Chang

    A bidirectional five-level power processing interface for low voltage battery energy storage system (BESS) is developed in this paper. This BESS consists of a bidirectional five-level DC-AC converter, a bidirectional dual boost/buck DC-DC converter and a battery set. This five-level DC-AC converter includes a bidirectional full-bridge converter and a bidirectional dual buck DC-DC converter. The five-level power processing interface can charge power to the battery set form the utility or discharge the power from the battery set to the utility depending on the demanded operation of user. A hardware prototype is developed to verify the performance of this BESS. Experimental results show the performance of the developed BESS is as expected.

  17. Low-Voltage Ride-Through Operation of Power Converters in Grid-Interactive Microgrids by Using Negative-Sequence Droop Control

    DEFF Research Database (Denmark)

    Zhao, Xin; Guerrero, Josep M.; Savaghebi, Mehdi;

    2017-01-01

    support the grid voltage, make profits, and also ride-through the voltage dip during the whole fault period. A two layer hierarchical control strategy is proposed in this paper. The primary controller consists of voltage and current inner loops, a conventional droop control and a virtual impedance loop......Due to the increasing penetration level of microgrids (MGs), it becomes a critical issue for MGs to help sustaining power system stability. Therefore, ancillary services, such as the low-voltage ride-through (LVRT) capability should be incorporated in MGs in order to guarantee stable operation...

  18. NEMO medium voltage converter factory acceptance, operational and final integration tests

    Science.gov (United States)

    Cocimano, Rosanna; NEMO Collaboration

    2011-01-01

    The NEMO Collaboration, as part of the KM3NeT EU-funded consortium, is developing technical solutions for the construction of a cubic-kilometer scale neutrino telescope in the Mediterranean sea several kilometers below the sea level and far from the shore. In this framework, after years of design, development, assembly and testing the Alcatel deep sea medium voltage power converter (MVC) is ready for deployment at 100 km from the Capo Passero shore station. The MVC converts the 10 kV to an instrument-friendly 375 V for a 10 kW power. The MVC will be presented with focus on the factory acceptance, operational and final integration tests that recently have been carried out.

  19. NEMO medium voltage converter factory acceptance, operational and final integration tests

    Energy Technology Data Exchange (ETDEWEB)

    Cocimano, Rosanna, E-mail: cocimano@lns.infn.i [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali del Sud, Via S. Sofia 62, 95123 Catania (Italy)

    2011-01-21

    The NEMO Collaboration, as part of the KM3NeT EU-funded consortium, is developing technical solutions for the construction of a cubic-kilometer scale neutrino telescope in the Mediterranean sea several kilometers below the sea level and far from the shore. In this framework, after years of design, development, assembly and testing the Alcatel deep sea medium voltage power converter (MVC) is ready for deployment at 100 km from the Capo Passero shore station. The MVC converts the 10 kV to an instrument-friendly 375 V for a 10 kW power. The MVC will be presented with focus on the factory acceptance, operational and final integration tests that recently have been carried out.

  20. A Novel Neutral Point Voltage Control Strategy for Three-Level NPC APF Based on SVPWM

    Directory of Open Access Journals (Sweden)

    Yao Xiaolong

    2015-01-01

    Full Text Available The unbalance of the neutral point voltage is an inherent problem of three-level neutral-point-clamped (NPC Active Power Filter (APF; this paper analyzes the causes of unbalanced neutral point voltage and studies the reason of the unbalance of the neutral point voltage. A novel neutral point voltage control strategy using Space Vector Pulse Width Modulation (SVPWM is proposed. The proposed strategy is based on the traditional SVPWM, by controlling the effect time of small vector, which can change the state of the midpoint voltage fluctuation, and the neutral point voltage can be maintained balance. The influence of the vector on neutral point balance is investigated in depth. Simulation results show the neutral point voltage balancing control strategy based on SPWM is effective.

  1. Evaluation of Conservation Voltage Reduction (CVR) on a National Level

    Energy Technology Data Exchange (ETDEWEB)

    Schneider, Kevin P.; Fuller, Jason C.; Tuffner, Francis K.; Singh, Ruchi

    2010-09-29

    Conservation Voltage Reduction (CVR) is a reduction of energy consumption resulting from a reduction of feeder voltage. While there have been numerous CVR systems deployed in North America there has been little substantive analytic analysis of the effect; the majority of the published results are based on empirical field measurements. Since these results are based on empirical measurements it is difficult to extrapolate how this technology will behave on the various types of distribution feeders found throughout the nation. This report has utilized the Taxonomy of Prototypical feeder developed under the Modern Grid Initiative (MGI), now the Modern Grid Strategy (MGS), in order to estimate the benefits of CVR on multiple distribution feeder types. This information will then be used to determine an estimate of the national benefits of a wide scale deployment of CVR.

  2. Operating Standby Redundant Controller to Improve Voltage Source Inverter Reliability

    Science.gov (United States)

    2007-12-01

    was built with two FPGAs programmed using XILINX System Generator and ISE foundation with a discrete algorithm representing the controller...Xilinx’s System Generator after parsing % H:\\Docs\\work_files\\faculty forms\\lab development\\buck_converter\\black_box_buck.vhd 121...this_block.setTopLevelLanguage(’VHDL’); this_block.setEntityName(’code’); % System Generator has to assume that your entity has a

  3. Loading Analysis of Modular Multi-level Converter for Offshore High-voltage DC Application under Various Grid Faults

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Loh, Poh Chiang;

    2016-01-01

    The modular multi-level converter has become an interesting candidate in high-voltage DC systems due to its higher voltage levels and modular construction. Low-voltage ride-through is an important grid requirement for modular multi-level converter–high-voltage DC since not only causes control cha...... be of importance for the design of the cooling system....

  4. A Component-Reduced Zero-Voltage Switching Three-Level DC-DC Converter

    DEFF Research Database (Denmark)

    Qin, Zian; Pang, Ying; Wang, Huai;

    2016-01-01

    The basic Zero-Voltage Switching (ZVS) three-level DC-DC converter has one clamping capacitor to realize the ZVS of the switches, and two clamping diodes to clamp the voltage of the clamping capacitor. In order to reduce the reverse recovery loss of the diode as well as its cost, this paper...... proposes to remove one of the clamping diodes in basic ZVS three-level DC-DC converter. With less components, the proposed converter can still have a stable clamping capacitor voltage, which is clamped at half of the dc link voltage. Moreover, the ZVS performance will be influenced by removing the clamping...

  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. Common voltage eliminating of SVM diode clamping three-level inverter connected to grid

    DEFF Research Database (Denmark)

    Guo, Yougui; Zeng, Ping; Zhu, Jieqiong

    2011-01-01

    A novel method of common voltage eliminating is put forward for SVM diode clamping three-level inverter connected to grid by calculation of common voltage of its various switching states. PLECS is used to model this three-level inverter connected to grid and good results are obtained. First...... analysis of common mode voltage for switching states of diode clamping 3-level inverter is given in detail. Second the common mode voltage eliminating control strategy of SVM is described for diode clamping three-level inverter. Third, PLECS is briefly introduced. Fourth, the modeling of diode clamping...... three-level inverter is presented with PLECS. Finally, a series of simulations are carried out. The simulation results tell us PLECS is a very powerful tool to real power circuits modeling. They have also verified that proposed common mode voltage eliminating control strategy of SVM is feasible...

  7. 16nm planar process CMOS SRAM cell design: Analysis of Operating Voltage and Temperature Effect

    Directory of Open Access Journals (Sweden)

    Rohit Sharma

    2013-09-01

    Full Text Available Purpose: CMOS devices are scaling down to nano ranges resulting in increased process variations and short channel effects which not only affect the reliability of the device but also performance expectations. The SRAM design uses the smallest transistors possible and is also susceptible to reliability issues and process variations, making it an ideal benchmark circuit to compare the two technologies [1]. Low power static-random access memories (SRAM have become a critical component in modern VLSI systems. They occupy a large portion of area and accounts for a major component of power consumption in today’s VLSI circuits. In this paper we intend to analyse the performance of a traditional 6T SRAM cell of 16nm Complementary Metal Oxide Semiconductor (CMOS technology with change in Operating Voltage and Temperature. Aim: The aim of the paper is to study the effect of the SNM dependencies on the operating voltage and temperatureApproach: Conventional 6T SRAM are designed using predictive technology model developed by Arizona State University [2] of 16nm planar Low Power CMOS and variation of SNM with operating voltage and temperature are simulated and studied using hspice.Findings: Variations in the operating voltages and temperature strongly impact the stability of an SRAM cell at 16nm. Comparative study is done for predictive 16nm based conventional 6T SRAM cell by varying operating voltage and temperature. A methodology to select operating voltage is suggested which can be used in an early stage of a design cycle to optimise stability margins in nanometer regime

  8. Efficient Low-Voltage Operation of a CW Gyrotron Oscillator at 233 GHz.

    Science.gov (United States)

    Hornstein, Melissa K; Bajaj, Vikram S; Griffin, Robert G; Temkin, Richard J

    2007-02-01

    The gyrotron oscillator is a source of high average power millimeter-wave through terahertz radiation. In this paper, we report low beam power and high-efficiency operation of a tunable gyrotron oscillator at 233 GHz. The low-voltage operating mode provides a path to further miniaturization of the gyrotron through reduction in the size of the electron gun, power supply, collector, and cooling system, which will benefit industrial and scientific applications requiring portability. Detailed studies of low-voltage operation in the TE(2) (,) (3) (,) (1) mode reveal that the mode can be excited with less than 7 W of beam power at 3.5 kV. During CW operation with 3.5-kV beam voltage and 50-mA beam current, the gyrotron generates 12 W of RF power at 233.2 GHz. The EGUN electron optics code describes the low-voltage operation of the electron gun. Using gun-operating parameters derived from EGUN simulations, we show that a linear theory adequately predicts the low experimental starting currents.

  9. Co-ordinated voltage control of DFIG wind turbines in uninterrupted operation during grid faults

    DEFF Research Database (Denmark)

    Hansen, Anca Daniela; Michalke, G.; Sørensen, Poul Ejnar

    2007-01-01

    is implemented in the power system simulation toolbox PowerFactory DIgSILENT. The DFIG wind farm ride-through capability and contribution to voltage control in the power system are assessed and discussed by means of simulations with the use of a transmission power system generic model developed and delivered......-side converter as long as it is not blocked by the protection system, otherwise the grid-side converter takes over the voltage control. Moreover, the article presents a DFIG wind farm model equipped with a grid fault protection system and the described co-ordinated voltage control. The whole DFIG wind farm model...... by the Danish Transmission System Operator Energinet.dk. The simulation results show how a DFIG wind farm equipped with voltage control can help a nearby active stall wind farm to ride through a grid fault, without implementation of any additional ride-through control strategy in the active stall wind farm....

  10. Threshold Voltage of MOSFET Devices Extracted by Normalized Mutual Integral Difference Operator

    Institute of Scientific and Technical Information of China (English)

    HEJin; ZHENGTaolei; ZHANGXing; WANGYangyuan

    2003-01-01

    The threshold voltage of MOSFETs to be extracted by a novel experimental method named the nor-realized mutual integral difference operator has been inves-tigated in this paper. The basic principle of this method is to use the extreme spectral characteristics of the nor-realized mutual integral difference result of the MOSFET transfer characteristics to find the threshold voltage. Ap-plication of this method has also been demonstrated nu-merically in extracting the threshold voltage of MOS de-vices with the different effective channel length and par-asitic series resistance. The results show this method is sensitive to the channel length variation while insensitive to the parasitic resistance component. The extracted re-sults on the threshold voltage of MOSFET devices have been compared with those obtained by the second deriva-tive method and the agreements have been found, showing the advantage of the method presented here.

  11. Comparison of microbial electrolysis cells operated with added voltage or by setting the anode potential

    KAUST Repository

    Nam, Joo-Youn

    2011-08-01

    Hydrogen production in a microbial electrolysis cell (MEC) can be achieved by either setting the anode potential with a potentiostat, or by adding voltage to the circuit with a power source. In batch tests the largest total gas production (46 ± 3 mL), lowest energy input (2.3 ± 0.3 kWh/m 3 of H2 generated), and best overall energy recovery (E+S = 58 ± 6%) was achieved at a set anode potential of EAn = -0.2 V (vs Ag/AgCl), compared to set potentials of -0.4 V, 0 V and 0.2 V, or an added voltage of Eap = 0.6 V. Gas production was 1.4 times higher with EAn = -0.2 V than with Eap = 0.6 V. Methane production was also reduced at set anode potentials of -0.2 V and higher than the other operating conditions. Continuous flow operation of the MECs at the optimum condition of EAn = -0.2 V initially maintained stable hydrogen gas production, with 68% H2 and 21% CH4, but after 39 days the gas composition shifted to 55% H2 and 34% CH 4. Methane production was not primarily anode-associated, as methane was reduced to low levels by placing the anode into a new MEC housing. These results suggest that MEC performance can be optimized in terms of hydrogen production rates and gas composition by setting an anode potential of -0.2 V, but that methanogen proliferation must be better controlled on non-anodic surfaces. © 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

  12. A Voltage Regulator for Parallel Operated Isolated Synchronous Generators Using Statcom

    Directory of Open Access Journals (Sweden)

    Sravanthi Gudipati,

    2014-02-01

    Full Text Available Reactive power (vars is required to maintain the voltage to deliver active power through transmission lines. Generator and other loads require reactive power to convert the flow of electrons into useful work. When there is not enough reactive power, the voltage sags down and it is not possible to push the power demanded by loads through the lines. Thus reactive power is injected using the compensating device STATCOM.The Paper deals on static synchronous compensator (STATCOM which is connected to the parallel operated isolated synchronous generators to drive a 3-phase load. These generators are driven by constant prime mover like diesel engine,bio-mass,gasoline,steam turbine etc.Three single phase IGBT based Voltage source converter (VSC along with 3-single phase transformers and self supported D.C bus is used as a voltage controller. The project deals with controlling a STATCOM using non-linear techniques that involves hysteresis current control and Park’s transformation. The voltage controller of parallel operated generators for feeding 3-phase loads driven by constant speed prime mover like Hydraulic turbine governor model helps in satisfactory operation under varying loads and in load balancing. If the line current is less than the expected, the compensating current generated by STATCOM is taken by loads.

  13. High voltage threshold for stable operation in a dc electron gun

    Science.gov (United States)

    Yamamoto, Masahiro; Nishimori, Nobuyuki

    2016-07-01

    We report clear observation of a high voltage (HV) threshold for stable operation in a dc electron gun. The HV hold-off time without any discharge is longer than many hours for operation below the threshold, while it is roughly 10 min above the threshold. The HV threshold corresponds to the minimum voltage where discharge ceases. The threshold increases with the number of discharges during HV conditioning of the gun. Above the threshold, the amount of gas desorption per discharge increases linearly with the voltage difference from the threshold. The present experimental observations can be explained by an avalanche discharge model based on the interplay between electron stimulated desorption (ESD) from the anode surface and subsequent secondary electron emission from the cathode by the impact of ionic components of the ESD molecules or atoms.

  14. Neutral-point voltage dynamic model of three-level NPC inverter for reactive load

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Munk-Nielsen, Stig; Busquets-Monge, Sergio

    2012-01-01

    A three-level neutral-point-clamped inverter needs a controller for the neutral-point voltage. Typically, the controller design is based on a dynamic model. The dynamic model of the neutral-point voltage depends on the pulse width modulation technique used for the inverter. A pulse width modulati...

  15. Five-Level Converter with Low Switching Frequency Applied as DC Voltage Supply

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg

    1999-01-01

    This paper describes the use of a multi-level converter as a DC supply. Equations for the converter will be deduced in the nondissipative case. The equations provide solutions to DC voltage and the angle of converter voltage. In addition the spectrum for the harmonics after the elimination...

  16. An ANN Based Capicitor Voltage Balancing Method For Neutral Point Clamped Multi-Level Inverter

    Directory of Open Access Journals (Sweden)

    P.J.S. Praveen,

    2015-11-01

    Full Text Available Multi-level inverters are became popular for usage in medium voltage, low voltage power applications due to flexibility in control and better performance characteristics in terms of harmonic regulation. Neutral point clamped are popular as they require less number of sources as their input when compared with their counter parts i.e. cascaded multi-level inverters and found to be reliable when compared with flying capacitor based multi-level inverters. But when neutral clamped technologies are used for generation of three-phase voltages, the capacitors that are connected at input side experiences imbalance in their voltages, this makes neutral point clamped multi-level inverters less reliable. In the proposed work an attempt is made to study circuits that balances the capacitor voltages and a scheme is investigated for balancing the capacitor voltages. Method proposed in [1] uses PID controller for balancing the capacitor voltages. In this project PI based control scheme and artificial neural network (ANN based control scheme for the front end circuit shown in [1] are designed for achieving balance among the capacitor voltages. The proposed control scheme is simulated with the help of Simpowersystems block set and neural network toolbox of MATLAB software for different load conditions. Results obtained from ANN based controller and PI controller are presented.

  17. Operation of grid-connected DFIG under unbalanced grid voltage condition

    NARCIS (Netherlands)

    Zhou, Y.; Bauer, P.; Ferreira, J.A.; Pierik, J.

    2009-01-01

    Doubly fed induction generator (DFIG) still shares a large part in today's wind power market. It provides the benefits of variable speed operation cost-effectively, and can control its active and reactive power independently. Crowbar protection is often adopted to protect the rotor-side voltage sour

  18. Voltage Harmonic Compensation of a Microgrid Operating in Islanded and Grid-Connected Modes

    DEFF Research Database (Denmark)

    Savaghebi, Mehdi; Jalilian, Alireza; Vasquez, Juan C.

    2011-01-01

    In this paper, a method for voltage harmonic compensation in a microgrid operating in islanded and gridconnected modes is presented. Harmonic compensation is done through proper control of distributed generators (DGs) interface converters. In order to achieve proper sharing of the compensation...

  19. Monitoring operating temperature and supply voltage in achieving high system dependability

    NARCIS (Netherlands)

    Khan, M.A.; Kerkhoff, Hans G.

    2013-01-01

    System dependability being a set of number of attributes, of which the important reliability, heavily depends on operating temperature and supply voltage. Any change beyond the designed specifications may change the system performance and could result in system reliability and hence dependability

  20. Monitoring operating temperature and supply voltage in achieving high system dependability

    NARCIS (Netherlands)

    Khan, M.A.; Kerkhoff, Hans G.

    2013-01-01

    System dependability being a set of number of attributes, of which the important reliability, heavily depends on operating temperature and supply voltage. Any change beyond the designed specifications may change the system performance and could result in system reliability and hence dependability pr

  1. Monitoring operating temperature and supply voltage in achieving high system dependability

    NARCIS (Netherlands)

    Khan, Muhammad Aamir; Kerkhoff, Hans G.

    2013-01-01

    System dependability being a set of number of attributes, of which the important reliability, heavily depends on operating temperature and supply voltage. Any change beyond the designed specifications may change the system performance and could result in system reliability and hence dependability pr

  2. Real time diagnostic for operation at a CW low voltage FEL

    Energy Technology Data Exchange (ETDEWEB)

    Balfour, C.; Shaw, A.; Mayhew, S.E. [and others

    1995-12-31

    At Liverpool University, a system for single user control of an FEL has been designed to satisfy the low voltage FEL (ie 200kV) operational requirements. This system incorporates many aspects of computer automation for beam diagnostics, radiation detection and vacuum system management. In this paper the results of the development of safety critical control systems critical control systems are reported.

  3. A novel low-voltage operational amplifier for low-power pipelined ADCs

    Energy Technology Data Exchange (ETDEWEB)

    Fan Mingjun; Ren Junyan; Guo Yao; Li Ning; Ye Fan; Li Lian, E-mail: 052052003@fudan.edu.c [State Key Laboratory of ASIC and System, Fudan University, Shanghai 200433 (China)

    2009-01-15

    A novel low-voltage two-stage operational amplifier employing class-AB architecture is presented. The structure utilizes level-shifters and current mirrors to create the class-AB behavior in the first and second stages. With this structure, the transconductances of the two stages are double compared with the normal configuration without class-AB behaviors with the same current consumption. Thus power can be saved and the operation frequency can be increased. The nested cascode miller compensation and symmetric common-mode feedback circuits are used for large unit-gain bandwidth, good phase margin and stability. Simulation results show that the sample-and-hold of the 12-bit 40-Ms/s pipelined ADC using the proposed amplifier consumes only 5.8 mW from 1.2 V power supply with signal-to-noise-and-distortion ratio 89.5 dB, spurious-free dynamic range 95.7 dB and total harmonic distortion -94.3 dB with Nyquist input signal frequency.

  4. A novel low-voltage operational amplifier for low-power pipelined ADCs

    Science.gov (United States)

    Mingjun, Fan; Junyan, Ren; Yao, Guo; Ning, Li; Fan, Ye; Lian, Li

    2009-01-01

    A novel low-voltage two-stage operational amplifier employing class-AB architecture is presented. The structure utilizes level-shifters and current mirrors to create the class-AB behavior in the first and second stages. With this structure, the transconductances of the two stages are double compared with the normal configuration without class-AB behaviors with the same current consumption. Thus power can be saved and the operation frequency can be increased. The nested cascode miller compensation and symmetric common-mode feedback circuits are used for large unit-gain bandwidth, good phase margin and stability. Simulation results show that the sample-and-hold of the 12-bit 40-Ms/s pipelined ADC using the proposed amplifier consumes only 5.8 mW from 1.2 V power supply with signal-to-noise-and-distortion ratio 89.5 dB, spurious-free dynamic range 95.7 dB and total harmonic distortion -94.3 dB with Nyquist input signal frequency.

  5. The Operational Level of War

    Science.gov (United States)

    1985-12-01

    Ramsay III, Dr. William G. Robertson, Major Claude R. Sasso, and Lieutenant Colonel Gary H. Wade. We owe special thanks to a few individuals who...3942 (preceding the decisive battle at El Alamein). The article outlines General Sir Claude Auchinleck’s attempts to restore the lagging offensive...Western Front in 1918. It is an excellent study of the operations of one corps in World War I. Morin , Michael J. "Does NATO Need a New Conventional

  6. Schottky bipolar I-MOS: An I-MOS with Schottky electrodes and an open-base BJT configuration for reduced operating voltage

    Science.gov (United States)

    Kannan, N.; Kumar, M. Jagadesh

    2017-04-01

    In this paper, we have proposed a novel impact ionization MOS (I-MOS) structure, called the Schottky bipolar I-MOS, with Schottky source and drain electrodes and utilizing the open-base bipolar junction transistor (BJT) configuration for achieving reduction in the operating voltage of the I-MOS transistor. We report, using 2-D simulations, a low operating voltage (∼1.1 V) and a low subthreshold swing (∼3.6 mV/Decade). For the corresponding p-i-n I-MOS, the operating voltage is ∼5.5 V. The operating voltage of the Schottky bipolar I-MOS is the lowest reported operating voltage for silicon based I-MOS transistors. The nearly 80% reduction in the operating voltage of the Schottky bipolar I-MOS makes it suitable for applications requiring low operating voltages. The Schottky bipolar I-MOS is also expected to have an improved reliability over the p-i-n I-MOS since high energy carriers, induced by impact ionization near the drain, do not have to pass under the gate region in the channel. The use of Schottky contacts instead of heavily doped source and drain regions and the low channel doping level reduces the required thermal budget for device fabrication. The low operating voltage, low subthreshold swing and possibly improved reliability of the Schottky bipolar I-MOS, makes it a potential solution for applications where steep subthreshold slope transistors are being explored as alternative to the conventional MOS transistor.

  7. Monolithically integrated enhancement/depletion-mode AlGaN/GaN HEMTs SRAM unit and voltage level shifter using fluorine plasma treatment

    Science.gov (United States)

    Yonghe, Chen; Xuefeng, Zheng; Jincheng, Zhang; Xiaohua, Ma; Yue, Hao

    2016-05-01

    A GaN-based E/D mode direct-couple logic 6 transistors SRAM unit and a voltage level shifter were designed and fabricated. E-mode and D-mode AlGaN/GaN HEMTs were integrated in one wafer using fluorine plasma treatment and using a moderate AlGaN barrier layer heterojunction structure. The 6 transistors SRAM unit consists of two symmetrical E/D mode inverters and two E-mode switch HEMTs. The output low and high voltage of the SRAM unit are 0.95 and 0.07 V at a voltage supply of 1 V. The voltage level shifter lowers the supply voltage using four Ni-AlGaN Schottky diodes in a series at a positive supply voltage of 6 V and a negative supply voltage of -6 V. By controlling the states of inverter modules of the level shifter in turn, the level shifter offers two channel voltage outputs of -0.5 and -5 V. The flip voltage of the level shifter is 0.76 V. Both the SRAM unit and voltage shifter operate correctly, demonstrating the promising potential for GaN-based E/D mode digital and analog integrated circuits. Several considerations are proposed to avoid the influence of threshold voltage degradation of D-mode and E-mode HEMT on the operation of the circuit. Project supported by the National Natural Science Foundation of China (No. 61334002), the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory (No. ZHD201206), and the Program for New Century Excellent Talents in University (No. NCET-12-0915).

  8. Optimal Constant DC Link Voltage Operation of aWave Energy Converter

    Directory of Open Access Journals (Sweden)

    Mats Leijon

    2013-04-01

    Full Text Available This article proposes a simple and reliable damping strategy for wave powerfarm operation of small-scale point-absorber converters. The strategy is based on passiverectification onto a constant DC-link, making it very suitable for grid integration of the farm.A complete model of the system has been developed in Matlab Simulink, and uses real sitedata as input. The optimal constant DC-voltage is evaluated as a function of the significantwave height and energy period of the waves. The total energy output of the WEC is derivedfor one year of experimental site data. The energy output is compared for two cases, onewhere the optimal DC-voltage is determined and held constant at half-hour basis throughoutthe year, and one where a selected value of the DC-voltage is kept constant throughout theyear regardless of sea state.

  9. False Operation of Static Random Access Memory Cells under Alternating Current Power Supply Voltage Variation

    Science.gov (United States)

    Sawada, Takuya; Takata, Hidehiro; Nii, Koji; Nagata, Makoto

    2013-04-01

    Static random access memory (SRAM) cores exhibit susceptibility against power supply voltage variation. False operation is investigated among SRAM cells under sinusoidal voltage variation on power lines introduced by direct RF power injection. A standard SRAM core of 16 kbyte in a 90 nm 1.5 V technology is diagnosed with built-in self test and on-die noise monitor techniques. The sensitivity of bit error rate is shown to be high against the frequency of injected voltage variation, while it is not greatly influenced by the difference in frequency and phase against SRAM clocking. It is also observed that the distribution of false bits is substantially random in a cell array.

  10. Optimizing the CEBAF Injector for Beam Operation with a Higher Voltage Electron Gun

    CERN Document Server

    Hannon, F E; Kazimi, R

    2011-01-01

    Recent developments in the DC gun technology used at CEBAF have allowed an increase in operational voltage from 100kV to 130kV. In the near future this will be extended further to 200kV with the purchase of a new power supply. The injector components and layout at this time have been designed specifically for 100kV operation. It is anticipated that with an increase in gun voltage and optimization of the layout and components for 200kV operation, that the electron bunch length and beam brightness can be improved upon. This paper explores some upgrade possibilities for a 200kV gun CEBAF injector through beam dynamic simulations.

  11. 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.)

  12. The design, construction, and operation of long-distance high-voltage electricity transmission technologies.

    Energy Technology Data Exchange (ETDEWEB)

    Molburg, J. C.; Kavicky, J. A.; Picel, K. C.

    2008-03-03

    This report focuses on transmission lines, which operate at voltages of 115 kV and higher. Currently, the highest voltage lines comprising the North American power grid are at 765 kV. The grid is the network of transmission lines that interconnect most large power plants on the North American continent. One transmission line at this high voltage was built near Chicago as part of the interconnection for three large nuclear power plants southwest of the city. Lines at this voltage also serve markets in New York and New England, also very high demand regions. The large power transfers along the West Coast are generally at 230 or 500 kV. Just as there are practical limits to centralization of power production, there are practical limits to increasing line voltage. As voltage increases, the height of the supporting towers, the size of the insulators, the distance between conductors on a tower, and even the width of the right-of-way (ROW) required increase. These design features safely isolate the electric power, which has an increasing tendency to arc to ground as the voltage (or electrical potential) increases. In addition, very high voltages (345 kV and above) are subject to corona losses. These losses are a result of ionization of the atmosphere, and can amount to several megawatts of wasted power. Furthermore, they are a local nuisance to radio transmission and can produce a noticeable hum. Centralized power production has advantages of economies of scale and special resource availability (for instance, hydro resources), but centralized power requires long-distance transfers of power both to reach customers and to provide interconnections for reliability. Long distances are most economically served at high voltages, which require large-scale equipment and impose a substantial footprint on the corridors through which power passes. The most visible components of the transmission system are the conductors that provide paths for the power and the towers that keep these

  13. Reduced semiconductor three-level interline dynamic voltage restorer

    DEFF Research Database (Denmark)

    Zhang, Lei; Loh, Poh Chang; Gao, Feng;

    2011-01-01

    IDVR system are mainly attributed to its complexity in topology and underutilizations of semiconductors. Aimed to improve the system in these aspects, the paper proposes a new IDVR topology with 25% reduction in semiconductors totally used. The theoretical analysis and its operating principles are also...

  14. Power lateral pnp transistor operating with high current density in irradiated voltage regulator

    Directory of Open Access Journals (Sweden)

    Vukić Vladimir Đ.

    2013-01-01

    Full Text Available The operation of power lateral pnp transistors in gamma radiation field was examined by detection of the minimum dropout voltage on heavily loaded low-dropout voltage regulators LM2940CT5, clearly demonstrating their low radiation hardness, with unacceptably low values of output voltage and collector-emitter voltage volatility. In conjunction with previous results on base current and forward emitter current gain of serial transistors, it was possible to determine the positive influence of high load current on a slight improvement of voltage regulator LM2940CT5 radiation hardness. The high-current flow through the wide emitter aluminum contact of the serial transistor above the isolation oxide caused intensive annealing of the positive oxide-trapped charge, leading to decrease of the lateral pnp transistor's current gain, but also a more intensive recovery of the small-signal npn transistors in the control circuit. The high current density in the base area of the lateral pnp transistor immediately below the isolation oxide decreased the concentration of negative interface traps. Consequently, the positive influence of the reduced concentration of the oxide-trapped charge on the negative feedback reaction circuit, together with the favourable effect of reduced interface traps concentration, exceeded negative influence of the annealed oxide-trapped charge on the serial pnp transistor's forward emitter current gain.

  15. ASPECTS OF SURGE ARRESTERS’ MAXIMUM OPERATING VOLTAGE CHOICE FOR ELECTRICAL EQUIPMENT INSULATION PROTECTION IN 6-35 KV MAINS

    Directory of Open Access Journals (Sweden)

    Yu. N. Shumilov

    2013-09-01

    Full Text Available The paper shows that, in 6-35 kV mains, application of a non-linear surge arrester (SA with the maximum continuous admissible operating voltage which is 10% higher than the mains’ maximum operating voltage results in the SA protection from overheating and subsequent breakdown at nonnormable lifetime of single-phase arc faults.

  16. Carrier-Based Common Mode Voltage Control Techniques in Three-Level Diode-Clamped Inverter

    Directory of Open Access Journals (Sweden)

    Pradyumn Chaturvedi

    2012-01-01

    Full Text Available Switching converters are used in electric drive applications to produce variable voltage, variable frequency supply which generates harmful large dv/dt and high-frequency common mode voltages (CMV. Multilevel inverters generate lower CMV as compared to conventional two-level inverters. This paper presents simple carrier-based technique to control the common mode voltages in multilevel inverters using different structures of sine-triangle comparison method such as phase disposition (PD, phase opposition disposition (POD by adding common mode voltage offset signal to actual reference voltage signal. This paper also presented the method to optimize the magnitude of this offset signal to reduce CMV and total harmonic distortion in inverter output voltage. The presented techniques give comparable performance as obtained in complex space vector-based control strategy, in terms of number of commutations, magnitude, and rate of change of CMV and harmonic profile of inverter output voltage. Simulation and experimental results presented confirm the effectiveness of the proposed techniques to control the common mode voltages.

  17. EMI-EDGI Operational Level Agreement

    CERN Document Server

    Di Meglio, Alberto

    2012-01-01

    This document is the Operational Level Agreement signed by EMI and EDGI for the contribution of middleware from EDGI into the EMI distribution and the definition of service levels compatible with the existing EMI SLAs

  18. A dulal-functional medium voltage level DVR to limit downstream fault currents

    DEFF Research Database (Denmark)

    Li, Yun Wei; Vilathgamuwa, D. Mahinda; Loh, Poh Chiang

    2007-01-01

    , the DVR will therefore be tasked to mitigate even more faults involving downstream loads. Large fault currents would flow through the DVR during a downstream fault before the opening of a circuit breaker. This will cause the voltage at point of common coupling (PCC) to drop, which would affect the loads...... on the other parallel feeders connected to PCC. Furthermore, if not controlled properly, the DVR might also contribute to this PCC voltage sag in the process of compensating the missing voltage, thus further worsening the fault situation. To limit the flow of large line currents, and therefore restore the PCC...... voltage as well as protect the DVR system components, a downstream fault limiting function is proposed and integrated in the DVR operation. A flux-charge-model feedback algorithm is implemented so that the DVR would act as a large virtual inductance in series with the distribution feeder in fault...

  19. Five Level Laboratory var Compensator With Separated Floating DC Voltages

    DEFF Research Database (Denmark)

    Rasmussen, Tonny Wederberg

    1997-01-01

    The paper discuss a IGBT model of a 10kvar five level non clamped compensator build to in-vestigate principles about multilevel system. Pulse wide modulation with selective harmonic elimination for multilevel converter is described where one of the solution is made in the labo-ratory model. Also ...

  20. SF sub 6 quenched gas mixtures for streamer mode operation of RPCs at very low voltages

    CERN Document Server

    Aielli, G; Cardarelli, R; Di Ciaccio, A; Di Stante, L; Liberti, B; Paoloni, A; Pastori, E; Santonico, R

    2002-01-01

    In the present paper we describe a search for gases that allow to reduce the energy of the electrical discharge produced in Resistive Plate Chambers (RPCs) operated in streamer mode, by reducing both the operating voltage and the released charge. This can be achieved, with current gas mixtures of argon, tetrafluoroethane (TFE) and isobutane, by reducing the total amount of quenching components (TFE+isobutane) down to 10-15% and compensating for the lower gas quenching power with the addition of small amounts of SF sub 6. We show here that SF sub 6 , even for concentrations as low as 1% or less, has a strong effect in reducing the delivered charge in low quenched gases and allows to achieve a proper working mode of the RPC even at voltages as low as 4-5 kV over a 2 mm gas gap.

  1. New half-voltage and double phase operation of the Hermes III linear induction accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Mikkelson, K.A.; Westfall, R.L.; Harper-Slaboszewicz, V.J. (Sandia National Labs., Albuquerque, NM (United States)); Neely, S.M. (K-Tech Corp., Albuquerque, NM (United States))

    1991-01-01

    The standard operating mode produces bremsstrahlung with an endpoint energy of about 18 MeV. This paper describes a new mode with a 8.5 MeV endpoint energy and the same standard mode pulse characteristics achieved by operating only half of the accelerator at full charge with the advantage of minimal setup time. An extension of the new half-voltage mode is to use the other half of the accelerator for delivering a second pulse at a later time with the same technique. The double pulse mode is ideal for beam generation which requires a long interpulse time in the millisecond regime. The beam characteristics of the two half-voltage pulses are nearly identical with the nominal radiation pulse full width at half maximum of 21 ns and 10--90 risetime of 11 ns recorded by the same Compton diode radiation monitors on instruments triggered 30 ms apart.

  2. A semi-floating gate transistor for low-voltage ultrafast memory and sensing operation.

    Science.gov (United States)

    Wang, Peng-Fei; Lin, Xi; Liu, Lei; Sun, Qing-Qing; Zhou, Peng; Liu, Xiao-Yong; Liu, Wei; Gong, Yi; Zhang, David Wei

    2013-08-09

    As the semiconductor devices of integrated circuits approach the physical limitations of scaling, alternative transistor and memory designs are needed to achieve improvements in speed, density, and power consumption. We report on a transistor that uses an embedded tunneling field-effect transistor for charging and discharging the semi-floating gate. This transistor operates at low voltages (≤2.0 volts), with a large threshold voltage window of 3.1 volts, and can achieve ultra-high-speed writing operations (on time scales of ~1 nanosecond). A linear dependence of drain current on light intensity was observed when the transistor was exposed to light, so possible applications include image sensing with high density and performance.

  3. A Robust Control Scheme for Medium-Voltage-Level DVR Implementation

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Loh, Poh Chiang; Li, Yun Wei;

    2007-01-01

    In this paper, a robust control scheme with an outer Hinfin voltage control loop and an inner current control loop is designed and implemented on a medium-voltage (MV)-level dynamic voltage restorer (DVR) system. Through a simple selection of weighting functions, the synthesized Hinfin controller....../nonlinear load and induction motor load) conditions. It is shown that the proposed control scheme is effective in both balanced and unbalanced sag compensation and load disturbance rejection, as its robustness is explicitly specified....... of Hinfin controller weighting function selection, inner current loop tuning, and system disturbance rejection capability is presented. Finally, the designed control scheme is extensively tested on a laboratory 10-kV MV-level DVR system with varying voltage sag (balanced and unbalanced) and loading (linear...

  4. A low-voltage sense amplifier with two-stage operational amplifier clamping for flash memory

    Science.gov (United States)

    Guo, Jiarong

    2017-04-01

    A low-voltage sense amplifier with reference current generator utilizing two-stage operational amplifier clamp structure for flash memory is presented in this paper, capable of operating with minimum supply voltage at 1 V. A new reference current generation circuit composed of a reference cell and a two-stage operational amplifier clamping the drain pole of the reference cell is used to generate the reference current, which avoids the threshold limitation caused by current mirror transistor in the traditional sense amplifier. A novel reference voltage generation circuit using dummy bit-line structure without pull-down current is also adopted, which not only improves the sense window enhancing read precision but also saves power consumption. The sense amplifier was implemented in a flash realized in 90 nm flash technology. Experimental results show the access time is 14.7 ns with power supply of 1.2 V and slow corner at 125 °C. Project supported by the National Natural Science Fundation of China (No. 61376028).

  5. General and Simple Decision Method for DG Penetration Level in View of Voltage Regulation at Distribution Substation Transformers

    Directory of Open Access Journals (Sweden)

    Joon-Ho Choi

    2013-09-01

    Full Text Available A distribution system was designed and operated by considering unidirectional power flow from a utility source to end-use loads. The large penetrations of distributed generation (DG into the existing distribution system causes a variety of technical problems, such as frequent tap changing problems of the on-load tap changer (OLTC transformer, local voltage rise, protection coordination, exceeding short-circuit capacity, and harmonic distortion. In view of voltage regulation, the intermittent fluctuation of the DG output power results in frequent tap changing operations of the OLTC transformer. Thus, many utilities limit the penetration level of DG and are eager to find the reasonable penetration limits of DG in the distribution system. To overcome this technical problem, utilities have developed a new voltage regulation method in the distribution system with a large DG penetration level. In this paper, the impact of DG on the OLTC operations controlled by the line drop compensation (LDC method is analyzed. In addition, a generalized determination methodology for the DG penetration limits in a distribution substation transformer is proposed. The proposed DG penetration limits could be adopted for a simplified interconnection process in DG interconnection guidelines.

  6. Cell libraries for robust low-voltage operation in nanometer technologies

    Science.gov (United States)

    Gemmeke, Tobias; Ashouei, Maryam; Liu, Bo; Meixner, Michael; Noll, Tobias G.; de Groot, Harmke

    2013-06-01

    The key challenge of wireless sensor nodes is their total power dissipation, hampering their autonomous operation due to limited battery life time. Aggressive voltage scaling reduces both dynamic and leakage power, prolonging the battery life time. The challenges of aggressive voltage scaling into the subthreshold region includes the pronounced effect of process variability and the significantly reduced performance. In this paper, these challenges are addressed by first devising a novel cell library pruning methodology to ensure reliable voltage scaling based on the noise margin criterion. Using the proposed approach, further voltage scaling is possible, enabling more than 20% energy savings as compared to the classic approach of avoiding high fan-in cells and/or complex gates. Then, the design of standard cells for two dedicated design points is presented which considers both the transistor geometry (L, W, and the number of fingers) as well as the cell layout to achieve up to a 3× speed-up as compared to a conventional methodology. The result is also validated in measurement leading to the comparison of a datapath module of slightly better energy efficiency and 3× better performance.

  7. Analysis of bi-directional piezoelectric-based converters for zero-voltage switching operation

    DEFF Research Database (Denmark)

    Ekhtiari, Marzieh; Zhang, Zhe; Andersen, Michael A. E.

    2016-01-01

    This paper deals with a thorough analysis of zerovoltage switching especially for bi-directional, inductorless, piezoelectric transformer-based switch-mode power supplies with a half-bridge topology. Practically, obtaining zero-voltage switching for all of the switches in a bi......-directional piezoelectric power converter is a difficult task. However, the analysis in this work will be convenient for overcoming this challenge. The analysis defines the zero-voltage region indicating the operating points whether or not soft switching can be met over the switching frequency and load range. For the first...... time, a comprehensive analysis is provided, which can be used as a design guideline for applying control techniques in order to drive switches in piezoelectric transformer-based converters. This study further conveys the proposed method to the region where all the switches can obtain soft switching...

  8. 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....

  9. A current to voltage converter for cryogenics using a CMOS operational amplifier

    Science.gov (United States)

    Hayashi, K.; Saitoh, K.; Shibayama, Y.; Shirahama, K.

    2009-02-01

    We have constructed a versatile current to voltage (I-V) converter operating at liquid helium temperature, using a commercially available all-CMOS OPamp. It is valuable for cryogenic measurements of electrical current of nano-pico amperes, for example, in scanning probe microscopy. The I-V converter is thermally linked to liquid helium bath and self-heated up to 10.7 K. We have confirmed its capability of a transimpedance gain of 106 V/A and a bandwidth from DC to 200 kHz. In order to test the practical use for a frequency-modulation atomic force microscope, we have measured the resonance frequency shift of a quartz tuning fork at 32 kHz. In the operation of the I-V converter close to the sensor at liquid helium temperature, the signal-to-noise ratio has been improved to a factor of 13.6 compared to the operation at room temperature.

  10. Modeling and Optimal Operation of Distributed Battery Storage in Low Voltage Grids

    OpenAIRE

    Fortenbacher, Philipp; Mathieu, Johanna L.; Andersson, Göran

    2016-01-01

    Due to high power in-feed from photovoltaics, it can be expected that more battery systems will be installed in the distribution grid in near future to mitigate voltage violations and thermal line and transformer overloading. In this paper, we present a two-stage centralized model predictive control scheme for distributed battery storage that consists of a scheduling entity and a real-time control entity. To guarantee secure grid operation, we solve a robust multi-period optimal power flow (O...

  11. A Simple Strategy of Controlling a Balanced Voltage Capacitor in Single Phase Five-Level Inverter

    Directory of Open Access Journals (Sweden)

    Leonardus Heru Pratomo

    2015-03-01

    Full Text Available The five-level inverter has been used for many applications in renewable energy systems. Even though its harmonic distortion was lower than the conventional two-level inverter. The five-level converter has some disadvantages such as increasing power semiconductor, complex pulse width modulation control methods, and problem with the voltage balancing of the capacitor. This paper aims to propose a modified five-level inverter based on sinusoidal pulse width modulation using phase shifted carrier to enhancing the capacitor voltage balancing. This modified five-level inverter reduces the overall cost and the complexity of the pulse width modulator. Thus making the proposed control system highly simple. The performance and its controller were validated by means of standard laboratory equipments. The analysis, simulation and implementation result showed better performance of five-level inverter.

  12. Noise levels of amusement ride operators.

    Science.gov (United States)

    Gilbertson, Lynn R; Thies, Liza E; Vosburgh, Donna J H

    2017-04-01

    One of the leading causes of noise-induced hearing loss is occupational noise exposure; however, little attention has been given to the exposure among amusement ride operators. According to the International Association of Amusement Parks and Attractions, 600,000 ride operators are employed in the U.S. The first objective of this descriptive study was to evaluate if ride operators were exposed to noise levels over 85 dB. The second objective was to classify the ride features that led to the highest noise levels. 136 rides were measured at 17 total amusement parks, county fairs, and festivals in southern Wisconsin and northern Illinois during summer 2015. A sound level meter recorded noise measurements as close in proximity to the ride operator as possible. Each ride was measured for two or three complete ride cycles, which included loading and operating the ride. The sound level meter was programmed to measure noise as recommended by the American Conference of Governmental Industrial Hygienists and with no threshold. 18% of rides measured had projected noise levels greater than American Conference of Governmental Industrial Hygienists recommendation of 85 dB. A repeated measures model was used to analyze the complete ride cycle decibel levels. The model found that traveling carnival rides had significantly higher levels compared to the stationary amusement park rides (p levels than those without midway music (p amusement ride operators would be at risk for noise induced hearing loss and would require a hearing conservation program if the 8-hr time weighted averages were to follow the same trends as the complete ride cycle levels.

  13. Voltage-Level Selection of Future Two-Level LVdc Distribution Grids

    DEFF Research Database (Denmark)

    Diaz, Enrique Rodriguez; Chen, Fang; Quintero, Juan Carlos Vasquez

    2016-01-01

    significantly. Microgrids (MGs) come as a suitable solution for the installation of distributed sources in the low voltage grid, where most of the consumers are sparsely located. Microgrids ease the integration of distributed generators (DGs), especially renewable energy sources like solar panels and small wind...

  14. Space vector modulation strategy for neutral-point voltage balancing in three-level inverter systems

    DEFF Research Database (Denmark)

    Choi, Uimin; Lee, Kyo Beum

    2013-01-01

    This study proposes a space vector modulation (SVM) strategy to balance the neutral-point voltage of three-level inverter systems. The proposed method is implemented by combining conventional symmetric SVM with nearest three-vector (NTV) modulation. The conventional SVM is converted to NTV...... modulation by properly adding or subtracting a minimum gate-on time. In addition, using this method, the switching frequency is reduced and a decrease of switching loss would be yielded. The neutral-point voltage is balanced by the proposed SVM strategy without additional hardware or complex calculations...

  15. Performance, stability and operation voltage optimization of screen-printed aqueous supercapacitors

    Science.gov (United States)

    Lehtimäki, Suvi; Railanmaa, Anna; Keskinen, Jari; Kujala, Manu; Tuukkanen, Sampo; Lupo, Donald

    2017-01-01

    Harvesting micropower energy from the ambient environment requires an intermediate energy storage, for which printed aqueous supercapacitors are well suited due to their low cost and environmental friendliness. In this work, a systematic study of a large set of devices is used to investigate the effect of process variability and operating voltage on the performance and stability of screen printed aqueous supercapacitors. The current collectors and active layers are printed with graphite and activated carbon inks, respectively, and aqueous NaCl used as the electrolyte. The devices are characterized through galvanostatic discharge measurements for quantitative determination of capacitance and equivalent series resistance (ESR), as well as impedance spectroscopy for a detailed study of the factors contributing to ESR. The capacitances are 200–360 mF and the ESRs 7.9–12.7 Ω, depending on the layer thicknesses. The ESR is found to be dominated by the resistance of the graphite current collectors and is compatible with applications in low-power distributed electronics. The effects of different operating voltages on the capacitance, leakage and aging rate of the supercapacitors are tested, and 1.0 V found to be the optimal choice for using the devices in energy harvesting applications. PMID:28382962

  16. Analysis of doubly-fed induction machine operating at motoring mode subjected to voltage sag

    Directory of Open Access Journals (Sweden)

    Navneet Kumar

    2016-09-01

    Full Text Available Variable Speed (VS Pumped Storage Plants (PSP equipped with large asynchronous (Doubly-Fed Induction machines are emerging now in hydropower applications. Motoring mode of operation of Doubly-Fed Induction Machine (DFIM is essential and techno-economical in this application due to: (1 its uniqueness in active power controllability, (2 bulk power handing capability with less rated power converters in rotor circuit, and (3 integrating Renewable Energy Sources (RES. This paper investigates the performance of two DFIMs at different power ratings (2.2 kW and 2 MW under voltage sag with different attribute. The test results are analyzed in terms of the peaks in torque, speed, power taken and transient currents in rotor and stator circuits. During sag, stable region for DFIM operation along with speed and stator side reactive power input control is also illustrated. The negative effects of voltage sag are briefly discussed. MATLAB simulation is validated with experimentation. The various observations during simulation and experimental analysis are also supported by the theoretical explanations.

  17. High-density magnetoresistive random access memory operating at ultralow voltage at room temperature.

    Science.gov (United States)

    Hu, Jia-Mian; Li, Zheng; Chen, Long-Qing; Nan, Ce-Wen

    2011-11-22

    The main bottlenecks limiting the practical applications of current magnetoresistive random access memory (MRAM) technology are its low storage density and high writing energy consumption. Although a number of proposals have been reported for voltage-controlled memory device in recent years, none of them simultaneously satisfy the important device attributes: high storage capacity, low power consumption and room temperature operation. Here we present, using phase-field simulations, a simple and new pathway towards high-performance MRAMs that display significant improvements over existing MRAM technologies or proposed concepts. The proposed nanoscale MRAM device simultaneously exhibits ultrahigh storage capacity of up to 88 Gb inch(-2), ultralow power dissipation as low as 0.16 fJ per bit and room temperature high-speed operation below 10 ns.

  18. Hardware and software system for monitoring oil pump operation in power high-voltage transformers

    Directory of Open Access Journals (Sweden)

    Михайло Дмитрович Дяченко

    2017-07-01

    Full Text Available The article considers the basic prerequisites for the creation of an automated monitoring system for oil pumps of high-voltage transformers. This is due to the fact that the long operation of oil pumps results in deterioration and destruction of bearings, rubbing of the rotor, breakage and damage to the impeller, leakage, etc., which inevitably causes a significant decrease in the insulating properties of the transformer oil and leads to expenditures for its further recovery. False triggerings of gas protection sometimes occur. Continuous operation of the electric motor also requires additional equipment to protect the motor itself from various emergency situations, such as a short in the stator winding, a housing breakdown, an incomplete phase mode, etc. The use of stationary systems provides: diagnosing defects at an early stage of their development, increasing the reliability and longevity of the equipment components, increasing the overhaul period, decreasing the number of emergency stops, and adjusting the schedule of preventative maintenance. The basic principles of identification of the damaged part of the oil pump are given, the hardware and algorithmic solutions are considered in the work. The full-scale tests of the model sample on the power transformer of the high-voltage substation confirmed the assumption of the possibility of detecting the damaged unit separating it from the rest connected in one mechanical structure. A detailed analysis of the operation of each of the units is carried out by means of the general substation switchboard and displayed as graphs, diagrams and text messages. When the limit values of vibration are reached, faults in the operation of the unit are detected, the overlimit current values, a warning alarm is activated, and the command to disconnect the damaged unit is issued. The optimal solution for the organization of the information collection system using the principle of sensor networks, but combined

  19. Design and Construction of Low Cost High Voltage dc Power Supply for Constant Power Operation

    Science.gov (United States)

    Kumar, N. S.; Jayasankar, V.

    2013-06-01

    Pulsed load applications like laser based systems need high voltage dc power supplies with better regulation characteristics. This paper presents the design, construction and testing of dc power supply with 1 kV output at 300 W power level. The designed converter has half bridge switched mode power supply (SMPS) configuration with 20 kHz switching. The paper covers the design of half bridge inverter, closed loop control, High frequency transformer and other related electronics. The designed power supply incorporates a low cost OPAMP based feedback controller which is designed using small signal modelling of the converter. The designed converter was constructed and found to work satisfactorily as per the specifications.

  20. Five-Level Active-Neutral-Point-Clamped DC/DC Converter for Medium-Voltage DC Grids

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Chen, Zhe

    2017-01-01

    effectively eliminate high voltage leaps caused by the dead time effect. In addition, a capacitor voltage control strategy is proposed for the 5L-ANPC dc/dc converter to ensure the balanced flying capacitor voltage and desired five-level voltage waveforms. Finally, simulation and experimental studies......This paper proposes a five-level active-neutralpoint- clamped (5L-ANPC) dc/dc converter for applications in medium voltage dc (MVDC) grids. A modulation strategy is proposed for the 5L-ANPC dc/dc converter to generate multilevel voltage waveforms, which can effectively reduce voltage change rate dv...... are conducted, and the results have verified the proposed converter and control strategies....

  1. The new voltage level 48 V for vehicle power supply; Die neue Spannungsebene 48 V im Kraftfahrzeug

    Energy Technology Data Exchange (ETDEWEB)

    Doersam, Thomas [Daimler AG, Boeblingen (Germany). Bordnetzkonzepte; Kehl, Steffen [Porsche Aktiengesellschaft, Weissach (Germany). Sachgebiet verteilte Funktionen elektrische Energie und Verbrauch; Klinkig, Andreas [Volkswagen AG, Wolfsburg (Germany). Energiemanagement; Radon, Andre [Audi AG, Ingolstadt (Germany). Bordnetzkonzepte und Energieeffizienz; Sirch, Ottmar [BMW Group, Muenchen (Germany). Vorentwicklung Energiebordnetz

    2012-02-15

    The increasing requirements to the vehicle power supply in conventional cars have taken the 12 V power supply to its limits. The car manufacturers Audi, BMW, Daimler, Porsche and Volkswagen were aware of this subject very early and worked out a first specification for a second voltage level at 48 V. The OEMs explain the conditions and backgrounds for deriving the voltage range and the concepts, the tests and test conditions for any components which will be applied in this voltage level. Additionally, the car manufacturers describe the probably next milestones for standardization and the standard of the voltage level as well as some potential E/E architecture concepts. (orig.)

  2. Ion properties in a Hall current thruster operating at high voltage

    Science.gov (United States)

    Garrigues, L.

    2016-04-01

    Operation of a 5 kW-class Hall current Thruster for various voltages from 400 V to 800 V and a xenon mass flow rate of 6 mg s-1 have been studied with a quasi-neutral hybrid model. In this model, anomalous electron transport is fitted from ion mean velocity measurements, and energy losses due to electron-wall interactions are used as a tuned parameter to match expected electron temperature strength for same class of thruster. Doubly charged ions production has been taken into account and detailed collisions between heavy species included. As the electron temperature increases, the main channel of Xe2+ ion production becomes stepwise ionization of Xe+ ions. For an applied voltage of 800 V, the mass utilization efficiency is in the range of 0.8-1.1, and the current fraction of doubly charged ions varies between 0.1 and 0.2. Results show that the region of ion production of each species is located at the same place inside the thruster channel. Because collision processes mean free path is larger than the acceleration region, each type of ions experiences same potential drop, and ion energy distributions of singly and doubly charged are very similar.

  3. Challenges to Grid Synchronization of Single-Phase Grid-Connected Inverters in Zero-Voltage Ride-Through Operation

    DEFF Research Database (Denmark)

    Zhang, Zhen; Yang, Yongheng; Blaabjerg, Frede

    2016-01-01

    to remain connected under grid voltage sags (even zero voltage condition). In this case, much attention should be paid to the grid synchronization in such a way to properly ride-through grid faults. Thus, in this paper, the most commonly-used and recently-developed Phase Locked Loop (PLL) synchronization...... methods have been evaluated for single-phase grid-connected PV systems in the case of Zero-Voltage Ride-Through (ZVRT) operation. The performances of the prior-art PLL methods in response to zero voltage faults in terms of detection precision and dynamic response are assessed in this paper. Simulation...... results show that the Enhanced PLL (EPLL) and the Second Order Generalized Integrator based PLL (SOGI-PLL) are the most applicable to single-phase PV systems for ZVRT operation....

  4. New Voltage-Mode All-pass Filter Topology Employing Single Current Operational Amplifier

    Directory of Open Access Journals (Sweden)

    Hasan Çiçekli

    2016-02-01

    Full Text Available In this paper, a new voltage-mode all-pass filter topology based on single current operational amplifier (COA and the implementation of COA by using current conveyors are presented. The proposed topology employs three admittances and single active circuit element. COA implementation by using current conveyor blocks as sub-circuit contributes to workability of the COA employing circuits by using commercially available integrated circuits that can be employed as current conveyor. The validity of the proposed filter is verified by PSPICE simulation programme by using the MOSIS 0.35 micron CMOS process parameters. The simulation results agree well with the theoretical analysis and the circuit achieve a good total harmonic distortion (THD performance.

  5. Derivation of armature displacement and movement disturbances from current and voltage measurements on solenoid operated valves

    Energy Technology Data Exchange (ETDEWEB)

    Louati, Iskander Alexandre [AREVA NP GmbH (Germany). Service Sector Germany

    2009-07-01

    As part of the electric drive mechanisms of the safety system in nuclear power plants safety related solenoid operated valves (SOVs) are subject to design control, commissioning tests and periodical in-service inspections. AREVA has developed and qualified many methods and tools that have been embedded into as software tools called DAM for diagnosis and evaluation of the valve performance according to the KTA requirements. In the special case of COVs tracing the electric measurements with ADAM helps to detect anomalies at the SOVs and esp. those related to disturbances of the armature moved. The disturbances to be tested are divided into electrical and mechanical disturbances: voltage insufficiency, switch chattering; degradation of spring load, friction collaterally to armature displacement, partial or total obstruction of the armature.

  6. Maximum Power Point Tracking of Photovoltaic power Generation System Based on Fuzzy Approximation of Operating Point Voltage with Radiation Intensity

    Directory of Open Access Journals (Sweden)

    H. Ijadi

    2012-09-01

    Full Text Available In this paper, a method to track the maximum power of solar panels based on fuzzy logic is presented. The proposed method is based on the relationship between radiation intensity and the voltage of maximum power operating point. With this relationship, at any time by measuring the light intensity, voltage can be calculated at the maximum power point by using fuzzy approximation function. In order to verify the proposed method, simulation results are presented.

  7. DC-Link Capacitor Voltage Regulation for Three-Phase Three-Level Inverter-Based Shunt Active Power Filter with Inverted Error Deviation Control

    Directory of Open Access Journals (Sweden)

    Yap Hoon

    2016-07-01

    Full Text Available A new control technique known as inverted error deviation (IED control is incorporated into the main DC-link capacitor voltage regulation algorithm of a three-level neutral-point diode clamped (NPC inverter-based shunt active power filter (SAPF to enhance its performance in overall DC-link voltage regulation so as to improve its harmonics mitigation performances. In the SAPF controller, DC-link capacitor voltage regulation algorithms with either the proportional-integral (PI or fuzzy logic control (FLC technique have played a significant role in maintaining a constant DC-link voltage across the DC-link capacitors. However, both techniques are mostly operated based on a direct voltage error manipulation approach which is insufficient to address the severe DC-link voltage deviation that occurs during dynamic-state conditions. As a result, the conventional algorithms perform poorly with large overshoot, undershoot, and slow response time. Therefore, the IED control technique is proposed to precisely address the DC-link voltage deviation. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and experimental implementation utilizing a TMS320F28335 Digital Signal Processor (DSP are performed. Moreover, conventional algorithms with PI and FLC techniques are tested too for comparison purposes. Both simulation and experimental results are presented, confirming the improvement achieved by the proposed algorithm in terms of accuracy and dynamic response in comparison to the conventional algorithms.

  8. A current to voltage converter for cryogenics using a CMOS operational amplifier

    Energy Technology Data Exchange (ETDEWEB)

    Hayashi, K; Saitoh, K; Shibayama, Y; Shirahama, K [Department of Physics, Keio University, Yokohama 223-8522 (Japan)], E-mail: khayashi@a2.keio.jp

    2009-02-01

    We have constructed a versatile current to voltage (I-V) converter operating at liquid helium temperature, using a commercially available all-CMOS OPamp. It is valuable for cryogenic measurements of electrical current of nano-pico amperes, for example, in scanning probe microscopy. The I-V converter is thermally linked to liquid helium bath and self-heated up to 10.7 K. We have confirmed its capability of a transimpedance gain of 10{sup 6} V/A and a bandwidth from DC to 200 kHz. In order to test the practical use for a frequency-modulation atomic force microscope, we have measured the resonance frequency shift of a quartz tuning fork at 32 kHz. In the operation of the I-V converter close to the sensor at liquid helium temperature, the signal-to-noise ratio has been improved to a factor of 13.6 compared to the operation at room temperature.

  9. 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...

  10. Mitigating voltage fade in cathode materials by improving the atomic level uniformity of elemental distribution.

    Science.gov (United States)

    Zheng, Jianming; Gu, Meng; Genc, Arda; Xiao, Jie; Xu, Pinghong; Chen, Xilin; Zhu, Zihua; Zhao, Wenbo; Pullan, Lee; Wang, Chongmin; Zhang, Ji-Guang

    2014-05-14

    Lithium- and manganese-rich (LMR) layered-structure materials are very promising cathodes for high energy density lithium-ion batteries. However, their voltage fading mechanism and its relationships with fundamental structural changes are far from being well understood. Here we report for the first time the mitigation of voltage and energy fade of LMR cathodes by improving the atomic level spatial uniformity of the chemical species. The results reveal that LMR cathodes (Li[Li0.2Ni0.2M0.6]O2) prepared by coprecipitation and sol-gel methods, which are dominated by a LiMO2 type R3̅m structure, show significant nonuniform Ni distribution at particle surfaces. In contrast, the LMR cathode prepared by a hydrothermal assisted method is dominated by a Li2MO3 type C2/m structure with minimal Ni-rich surfaces. The samples with uniform atomic level spatial distribution demonstrate much better capacity retention and much smaller voltage fade as compared to those with significant nonuniform Ni distribution. The fundamental findings on the direct correlation between the atomic level spatial distribution of the chemical species and the functional stability of the materials may also guide the design of other energy storage materials with enhanced stabilities.

  11. High voltage electric potentials to enhance brain-derived neurotrophic factor levels in the brain.

    Science.gov (United States)

    Yanamoto, Hiroji; Nakajo, Yukako; Kataoka, Hiroharu; Iihara, Koji

    2013-01-01

    Development of a safe method to increase brain-derived neurotrophic factor (BDNF) levels in the brain is expected to enhance learning and memory, induce tolerance to cerebral infarction or tolerance to depressive state, improve glucose metabolism, and suppress appetite and body weight. We have shown that repetitive applications of high-voltage electric potential (HELP) to the body increase BDNF levels in the brain, improving learning and memory in mice. Here, we investigated the effects of HELP treatment for a chronic period on the BDNF levels in the mouse brain, and on body weight in mice and humans. Adult mice were exposed to 3.1 or 5.4 kV HELP (on the body), 5 h a day for 24 weeks, and BDNF levels in the brain and alterations in body weight were analyzed. Humans [age, 53.2 ± 15.5 years old; BMI, 27.8 ± 5.6 (mean ± SD, n = 6)] were exposed to 3.9 kV HELP (on the body) for 1 h a day, continuing for 33 months (2.8 years) under the monitor of body weight. In mice, the HELP application elevated BDNF levels in the brain at least temporarily, affecting body weight in a voltage- and time-dependent manner. In humans, the HELP treatment reduced body weight compared to the pretreated initial values without any aversive effects (p BDNF, and 5.4 kV HELP was considered as excessive. HELP with an appropriate voltage can be utilized to increase BDNF levels in the brain for a prolonged period. We anticipate further investigations to clarify the effect of the optimal-leveled HELP therapy on memory disturbances, neurological deficits after stroke, depression, diabetes, obesity and metabolic syndrome.

  12. Elimination of zero sequence circulating current between parallel operating three-level inverters

    DEFF Research Database (Denmark)

    Li, Kai; Wang, Xiaodong; Dong, Zhenhua

    2016-01-01

    In order to suppress the zero sequence circulating currents (ZSCCs) between parallel operating three level voltage source inverters with common AC and DC buses, a common mode voltage reduction PWM (CMVR-PWM) technique and neural point potentials (NPPs) control based method is proposed in this paper...... strategies, ZSCCs between parallel inverters can be eliminated effectively. This strategy has the advantage of without carrier synchronization and can be utilized to parallel operating inverters with different types of filter. Simulation result validate the proposed ZSCC elimination schemes....

  13. Wall-shaped electrodes for reducing the operation voltage of polymer-stabilized blue phase liquid crystal displays

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Miyoung; Kim, Min Su; Kang, Byeong Gyun; Kim, Mi-Kyung; Yoon, Sukin; Lee, Seung Hee [Polymer BIN Fusion Research Center, Department of Polymer Nano-Science and Technology, Chonbuk National University, Chonju, Chonbuk 561-756 (Korea, Republic of); Ge Zhibing; Rao Linghui; Gauza, Sebastian; Wu, Shin-Tson, E-mail: lsh1@chonbuk.ac.k, E-mail: swu@creol.ucf.ed [College of Optics and Photonics, University of Central Florida, Orlando, FL 32816 (United States)

    2009-12-07

    Polymer-stabilized blue phase liquid crystal displays based on the Kerr effect are emerging due to their submillisecond response time, wide view and simple fabrication process. However, the conventional in-plane switching device exhibits a relatively high operating voltage because the electric fields are restricted in the vicinity of the electrode surface. To overcome this technical barrier, we propose a partitioned wall-shaped electrode configuration so that the induced birefringence is uniform between electrodes throughout the entire cell gap. Consequently, the operating voltage is reduced by {approx} 2.8x with two transistors. The responsible physical mechanisms are explained.

  14. Comparison between 9-level hybrid asymmetric and conventional multi-level inverters for medium voltage application

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Blaabjerg, Frede

    2013-01-01

    A hybrid asymmetric 2-cell 9-level inverter is analysed and compared with two conventional multilevel inverters: the 9-level cascaded H-bridge and the 3-level diode clamped inverter, when used to drive an induction motor of 4.16kV/500kVA. In this analysis, Total Harmonic Distortion (THD), First...

  15. Medium voltage three-level converters for the grid connection of a multi-MW wind turbine

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig;

    2009-01-01

    Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter topo...

  16. PLANCK LFI Level 1 Processing During Operations

    Science.gov (United States)

    Morisset, N.; Rohlfs, R.; Türler, M.; Meharga, M.; Binko, P.; Beck, M.; Frailis, M.; Zacchei, A.; Galeotta, S.

    2008-08-01

    The PLANCK satellite with two on-board instruments, a Low Frequency Instrument (LFI) and a High Frequency Instrument (HFI) is foreseen to be launched in August 2008 with Ariane 5. The Data Processing Centre (DPC) in Trieste, Italy for LFI is responsible for processing the PLANCK LFI data. The ISDC data centre in Switzerland is responsible for developing/installing and maintaining the software for the LFI Level 1 data processing presented here. The main tasks of the Level 1 processing are to retrieve the daily available consolidated scientific and housekeeping (HK) data of the LFI instrument from the Mission Operation Centre in Darmstadt (MOC); to sort them by time and by type (detector, observing mode, etc...); to extract the spacecraft attitude information from auxiliary files; to flag the data according to several criteria; and to archive the resulting Time Ordered Information (TOI). The TOI data generated by the level 1 pipeline are the input for the more scientific LFI level 2 processing. The TOI are first stored in FITS format and then ingested into the Data Management Component (DMC) system, which is the interface to the LFI DPC database. In addition, the ISDC also developed software tools to display and perform a quick look analysis of the data.

  17. 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...

  18. Torque harmonics of an asynchronous motor supplied by a voltage- or current-sourced inverter quasi-square operation

    Energy Technology Data Exchange (ETDEWEB)

    Kyyrae, J. [Helsinki University of Technology, Institute of Intelligent Power Electronics, Espoo (Finland)

    1997-12-31

    Voltage- and current-sourced dc-ac converters operating in quasi-square area are compared. Their characteristics are calculated with switching vector, which is space-vector of switching functions. When the load is an asynchronous motor various analytical equations, including torque, are calculated efficiently. Motor current and torque approximations are compared with the simulated ones. (orig.) 6 refs.

  19. Thermal Optimized Operation of the Single-Phase Full-Bridge PV Inverter under Low Voltage Ride-Through Mode

    DEFF Research Database (Denmark)

    Wang, Huai; Yang, Yongheng; Blaabjerg, Frede

    2013-01-01

    The efficiency of 98% has been reported on transformer-less photovoltaic (PV) inverters and the penetration of grid-connected PV systems is booming as well. In the future, the PV systems are expected to contribute to the grid stability by means of low voltage ride-through operation and grid suppo...

  20. Capacity determination of a battery energy storage system based on the control performance of load leveling and voltage control

    Directory of Open Access Journals (Sweden)

    Satoru Akagi

    2016-01-01

    Full Text Available This paper proposes a method to determine the combined energy (kWh and power (kW capacity of a battery energy storage system and power conditioning system capacity (kVA based on load leveling and voltage control performances. Through power flow calculations, a relationship between the capacity combination and the control performance is identified and evaluated. A tradeoff relationship between the capacity combination and control performance is confirmed, and the proper capacity combination for operation is determined based on the evaluated relationship. In addition, the control performance of the capacity combination is evaluated through the power flow calculation, confirming that the proposed method is effective for determining the optimized capacity combination.

  1. 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).

  2. Minimum-Voltage Vector Injection Method for Sensorless Control of PMSM for Low-Speed Operations

    DEFF Research Database (Denmark)

    Xie, Ge; Lu, Kaiyuan; Kumar, Dwivedi Sanjeet

    2016-01-01

    In this paper, a simple signal injection method is proposed for sensorless control of PMSM at low speed, which ideally requires one voltage vector only for position estimation. The proposed method is easy to implement resulting in low computation burden. No filters are needed for extracting...... may also be further developed to inject two opposite voltage vectors to reduce the effects of inverter voltage error on the position estimation accuracy. The effectiveness of the proposed method is demonstrated by comparing with other sensorless control method. Theoretical analysis and experimental...

  3. A Pulse Width Modulation Scheme With Zero-sequence Voltage Injection for Single Phase Three-level NPC Rectifiers

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    A single phase three-level converter (shown in Fig. 1) has been widely applied in high-speed railway electrical traction drive systems. But the main technical drawback of the three-level converter is DC-link neutral point voltage drift. In order to solve this problem, it is important to understand the cause of DC-link neutral point voltage drift.

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

    DEFF Research Database (Denmark)

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

    2012-01-01

    with focus on low power consumption as well as low capacitive load between the floating half-bridge node and ground (output capacitance). The operation of the level-shifter is tested and verified by measurements on a prototype half-bridge gate driver. Results conclude stabile operation at 2.44kV, 50k...

  5. Design of Neutral-Point Voltage Controller of a Three-level NPC Inverter with Small DC-Link Capacitors

    DEFF Research Database (Denmark)

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

    2013-01-01

    A Neutral-Point-Clamped (NPC) three-level inverter with small dc-link capacitors is presented in this paper. The inverter requires zero average neutral-point current for stable neutral-point voltage. The small dc-link capacitors may not maintain capacitor voltage balance, even with zero neutral-point...... current. This may happen due to nonlinearities present in the circuit. This requires a fast control of the neutral-point voltage. A simple carrier based modulation strategy which allows modeling of the neutral-point voltage dynamics as a continuous function of power drawn from the inverter is proposed....... This continuous model shows that the neutral-point current is proportional to the power drawn from the inverter, and it enables the use of well established classical control theory for the neutral-point voltage controller design. A simple PI (proportional integral) controller is designed for the neutral-point...

  6. Design and development of high voltage high power operational amplifier using thick film technology

    Indian Academy of Sciences (India)

    Krishna Mohan Nutheti; Vinod S Chippalakatti; Shashikala Prakash

    2008-10-01

    Applications of power operational amplifiers (opamps) are increasing day by day in the industry as they are used in audio amplifiers, Piezo transducer systems and the electron deflection systems. Power operational amplifiers have all the features of a general purpose opamp except the additional power handling capability. The power handling feature can be achieved using an external circuitry around a regular opamp. Normally power opamps can deliver current more than 50 mA and can operate on the supply voltage more than ±25 V. This paper gives the details of one of the power opamps developed to drive the Piezo Actuators for Active Vibration Control (AVC) of aircraft/aerospace structures. The designed power opamp will work on ±200 V supply voltage and can deliver 200 mA current.

  7. Determination of threshold and maximum operating electric stresses for selected high voltage insulation. Task 3: Investigation of high voltage capacitor insulation

    Science.gov (United States)

    Sosnowski, M.; Eager, G. S., Jr.

    1984-03-01

    The threshold voltage of capacitor insulation was investigated. The experimental work was performed on samples prepared from commercial polypropylene insulated, liquid-filled capacitors. The samples were vacuum-impregnated with the original capacitor insulating liquid obtained from the manufacturer. A limited number of full-size capacitor elements also were tested. Impulse voltage breakdown tests with dc voltage prestressing were performed at room temperature and 75 C. From the results of these tests, the threshold voltage of the samples of the capacitor insulation was determined at both temperatures and that of the whole capacitor elements at room temperature. The threshold voltage of the capacitor insulation was found to be approximately equal to the impulse breakdown voltage. No difference was found between the threshold voltage at room temperature and at 75 C. The threshold voltage of the whole capacitor elements at room temperature was found to be equal to approximately 80% of the threshold voltage of the capacitor insulation samples.

  8. Potential L-Type Voltage-Operated Calcium Channel Blocking Effect of Drotaverine on Functional Models.

    Science.gov (United States)

    Patai, Zoltán; Guttman, András; Mikus, Endre G

    2016-12-01

    Drotaverine is considered an inhibitor of cyclic-3',5'-nucleotide-phophodiesterase (PDE) enzymes; however, published receptor binding data also support the potential L-type voltage- operated calcium channel (L-VOCC) blocking effect of drotaverine. Hence, in this work, we focus on the potential L-VOCC blocking effect of drotaverine by using L-VOCC-associated functional in vitro models. Accordingly, drotaverine and reference agents were tested on KCl-induced guinea pig tracheal contraction. Drotaverine, like the L-VOCC blockers nifedipine or diltiazem, inhibited the KCl-induced inward Ca(2+)- induced contraction in a concentration- dependent fashion. The PDE inhibitor theophylline had no effect on the KCl-evoked contractions, indicating its lack of inhibition on inward Ca(2+) flow. Drotaverine was also tested on the L-VOCC-mediated resting Ca(2+) refill model. In this model, the extracellular Ca(2+) enters the cells to replenish the emptied intracellular Ca(2+) stores. Drotaverine and L-VOCC blocker reference molecules inhibited Ca(2+) replenishment of Ca(2+)-depleted preparations detected by agonist-induced contractions in post-Ca(2+) replenishment Ca(2+)-free medium. Theophylline did not modify the Ca(2+) store replenishment after contraction. It seems that drotaverine, but not theophylline, inhibits inward Ca(2+) flux. The addition of CaCl2 to Ca(2+)-free medium containing the agonist induced inward Ca(2+) flow and subsequent contraction of Ca(2+)-depleted tracheal preparations. Drotaverine, similar to the L-VOCC blockers, inhibited inward Ca(2+) flow and blunted the slope of CaCl2-induced contraction in agonist containing Ca(2+)-free medium with Ca(2+)-depleted tracheal preparations. These results show that drotaverine behaves like L-VOCC blockers but, unlike PDE inhibitors using L-VOCC associated in vitro experimental models.

  9. Controlled operation of the Islanded portion of the CIGRE Low Voltage distribution network

    DEFF Research Database (Denmark)

    Mustafa, Ghullam; Bak-Jensen, Birgitte; Bak, Claus Leth;

    2017-01-01

    be switched to the Voltage-Frequency (VF) control mode. In case of islanding, the network loses it slack reference and this reference is established by the use of VF controller. The voltage and the frequency of the islanded MG deviate when it is disconnected from the transmission grid and these deviations...... are according to the load-generation imbalance in the islanded MG. The voltage and the frequency of the islanded MG can be restored to the permissible limits if the desired/exceeded amount of active and reactive power is injected/absorbed by the locally available sources in islanded MG. This paper proposes...... the control strategy which can compensate the problems of the voltage and the frequency deviations in the islanded MG. The selection of the VF controller for the most suitable DG unit of the LV test network is also presented in this paper and effectiveness of the controllers is verified by presenting...

  10. Pixel-level A/D conversion using voltage reset technique

    Institute of Scientific and Technical Information of China (English)

    Li Minzeng; Li Fule; Zhang Chun; Wang Zhihua

    2014-01-01

    This paper presents a 50 Hz 15-bit analog-to-digital converter (ADC) for pixel-level implementation in CMOS image sensors.The ADC is based on charge packets counting and adopts a voltage reset technique to inject charge packets.The core circuit for charge/pulse conversion is specially optimized for low power,low noise and small area.An experimental chip with ten pixel-level ADCs has been fabricated and tested for verification.The measurement result shows a standard deviation of 1.8 LSB for full-scale output.The ADC has an area of 45 × 45μm2 and consumes less than 2 μW in a standard 1P-6M 0.18μm CMOS process.

  11. ZnO/NiO diode-based charge-trapping layer for flash memory featuring low-voltage operation.

    Science.gov (United States)

    Sun, Chergn-En; Chen, Chin-Yu; Chu, Ka-Lip; Shen, Yung-Shao; Lin, Chia-Chun; Wu, Yung-Hsien

    2015-04-01

    A stacked oxide semiconductor of n-type ZnO/p-type NiO with diode behavior was proposed as the novel charge-trapping layer to enable low-voltage flash memory for green electronics. The memory performance outperforms that of other devices with high κ and a nanocrystal-based charge-trapping layer in terms of a large hysteresis memory window of 2.02 V with ±3 V program/erase voltage, a high operation speed of 1.88 V threshold voltage shift by erasing at -4 V for 1 ms, negligible memory window degradation up to 10(5) operation cycles, and 16.2% charge loss after 10 years of operation at 85 °C. The promising electrical characteristics can be explained by the negative conduction band offset with respect to Si of ZnO that is beneficial to electron injection and storage, the large number of trapping sites of NiO that act as other good storage media, and most importantly the built-in electric field between n-type ZnO and p-type NiO that provides a favorable electric field for program and erase operation. The process of diode-based flash memory is fully compatible with incumbent VLSI technology, and utilization of the built-in electric field ushers in a new avenue of accomplishing green flash memory.

  12. 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.

  13. High-Precision Multi-Wave Rectifier Circuit Operating in Low Voltage + 1.5 Volt Current Mode

    Directory of Open Access Journals (Sweden)

    Bancha Burapattanasiri

    2009-12-01

    Full Text Available This article is present high-precision multi-wave rectifier circuit operating in low voltage +/- 1.5 Volt current modes by CMOS technology 0.5 μm, receive input and give output in current mode, respond at high frequency period. The structure compound with high-speed current comparator circuit, current mirror circuit, and CMOS inverter circuit. PSpice program used for confirmation the performance of testing. The PSpice program shows operating of circuit is able to working at maximum input current 400 μAp-p, maximum frequency responding 200 MHz, high precision and low power losses, and non-precision zero crossing output signal.Keywords-component; rectifier circuit; high-precision; low voltage; current mode;

  14. Challenges to Grid Synchronization of Single-Phase Grid-Connected Inverters in Zero-Voltage Ride-Through Operation

    DEFF Research Database (Denmark)

    Zhang, Zhen; Yang, Yongheng; Blaabjerg, Frede;

    2016-01-01

    methods have been evaluated for single-phase grid-connected PV systems in the case of Zero-Voltage Ride-Through (ZVRT) operation. The performances of the prior-art PLL methods in response to zero voltage faults in terms of detection precision and dynamic response are assessed in this paper. Simulation......With the fast development in Photovoltaic (PV) technology, the relevant grid-connection requirements/standards are continuously being updated, and more challenges have been imposed on both single-phase and three-phase grid-connected PV systems. For instance, PV systems are currently required...... results show that the Enhanced PLL (EPLL) and the Second Order Generalized Integrator based PLL (SOGI-PLL) are the most applicable to single-phase PV systems for ZVRT operation....

  15. Flexible viologen electrochromic devices with low operational voltages using reduced graphene oxide electrodes.

    Science.gov (United States)

    Palenzuela, Jesús; Viñuales, Ana; Odriozola, Ibon; Cabañero, Germán; Grande, Hans J; Ruiz, Virginia

    2014-08-27

    Reduced graphene oxide (RGO) films have been electrodeposited on indium tin oxide-coated polyethylene terephthalate (ITO-PET) substrates from graphene oxide (GO) solutions, and the resulting flexible transparent electrodes have been used in electrochromic devices of ethyl viologen (EtV(2+)). The electrochromic performance of devices with bare ITO-PET electrodes and ITO-PET coated with RGO has been compared. Under continuous cycling tests up to large voltages, the RGO film was oxidized and dispersed in the electrochromic mixture. The resulting devices, which contained GO and RGO in the electrochromic mixture, showed lower switching voltages between the colored and bleached states. This electrocatalytic activity of the solution-phase GO/RGO pair toward the electrochemical reaction of the electrochromic redox couple (the dication EtV(2+) and the radical cation EtV(+•)) allowed devices with an optical contrast higher than the contrast of those free of GO at the same applied voltage.

  16. Investigation of the Effects of Cathode Flow Fraction and Position on the Performance and Operation of the High Voltage Hall Accelerator

    Science.gov (United States)

    Kamhawi, Hani; Huang, Wensheng; Haag, Thomas

    2014-01-01

    The National Aeronautics and Space Administration (NASA) Science Mission Directorate In- Space Propulsion Technology office is sponsoring NASA Glenn Research Center (GRC) to develop a 4 kW-class Hall thruster propulsion system for implementation in NASA science missions. Tests were performed within NASA GRC Vacuum Facility 5 at background pressure levels that were six times lower than what has previously been attained in other vacuum facilities. A study was conducted to assess the impact of varying the cathode-to-anode flow fraction and cathode position on the performance and operational characteristics of the High Voltage Hall Accelerator (HiVHAc) thruster. In addition, the impact of injecting additional xenon propellant in the vicinity of the cathode was also assessed. Cathode-to-anode flow fraction sensitivity tests were performed for power levels between 1.0 and 3.9 kW. It was found that varying the cathode flow fraction from 5 to approximately 10% of the anode flow resulted in the cathode-to-ground voltage becoming more positive. For an operating condition of 3.8 kW and 500 V, varying the cathode position from a distance of closest approach to 600 mm away did not result in any substantial variation in thrust but resulted in the cathode-to-ground changing from -17 to -4 V. The change in the cathode-to-ground voltage along with visual observations indicated a change in how the cathode plume was coupling to the thruster discharge. Finally, the injection of secondary xenon flow in the vicinity of the cathode had an impact similar to increasing the cathode-to-anode flow fraction, where the cathode-to-ground voltage became more positive and discharge current and thrust increased slightly. Future tests of the HiVHAc thruster are planned with a centrally mounted cathode in order to further assess the impact of cathode position on thruster performance.

  17. Modeling and Control of Low Voltage Flexible Units for Enhanced Operation of Distribution Feeders

    DEFF Research Database (Denmark)

    Raboni, Pietro; Hu, Weihao; Chaudhary, Sanjay

    2013-01-01

    Battery (EVB) is proposed for providing primary regulation in grid connected mode and for hierarchically manage an islanded LV distribution feeder. The unit models are described and a novel EVB model directly based on manufacturer’s data is proposed and evaluated comparing its performances with Sim......PowerSystems library block. Moreover a voltage dependant power term is applied to the Voltage-Source Converter (VSC) control scheme of the EVB for improving the performances of the islanded feeder. The control is tested in case of under frequency and consequent load shedding occurring at the residential feeder...

  18. 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.

  19. Evaluation of Conservation Voltage Reduction with Analytic Hierarchy Process: A Decision Support Framework in Grid Operations Planning

    Directory of Open Access Journals (Sweden)

    Kyungsung An

    2016-12-01

    Full Text Available This paper presents a systematic framework to evaluate the performance of conservation voltage reduction (CVR by determining suitable substations for CVR in operations planning. Existing CVR planning practice generally only focuses on the energy saving aspect without taking other underlying attributes into account, i.e., network topology and reduced voltage effects on other substations. To secure the desired operating reserve and avoid any adverse impacts, these attributes should be considered for implementing CVR more effectively. This research develops a practical decision-making framework based on the analytic hierarchy process (AHP to quantify several of the aforementioned attributes. Candidate substations for CVR deployment are prioritized such that performances are compared in terms of power transfer distribution factor (PTDF, voltage sensitivity factor (VSF, and CVR factor. In addition, to meet a specified reserve requirement, an integer programming approach is adopted to select potential substations for CVR implementations. Case studies for a Korean electric power system under diverse operating conditions are performed to demonstrate the effectiveness of the proposed method.

  20. Investigation and Improvement of Transient Response of DVR at Medium Voltage Level

    DEFF Research Database (Denmark)

    Blaabjerg, Frede; Wei Li, Yun; Chaing Loh, Poh;

    2007-01-01

    An area of interest for dynamic voltage restorer (DVR) research is the damping of transient oscillations initiated at the start and at the recovery instant from a voltage sag. Nonlinear loads, with harmonic currents close to the DVR filter resonance frequency, can also excite the resonance...... oscillations. To compensate voltage sags and dampen high-frequency oscillations simultaneously, an investigation of the transient response of DVR is first carried out. Possible control schemes and their effects on the oscillation attenuation are also studied. Such studied control schemes include the commonly...... used single voltage loop control, voltage feedback plus reference feedforward control, and double-loop control with an outer voltage loop and an inner current loop. Subsequently, an effective and simple resonance damping method is proposed by employing a closed-loop control with an embedded two...

  1. Programmable Voltage-Mode Multifunction Filter Using Two Current Conveyors and One Operational Transconductance Amplifier

    OpenAIRE

    Muhammad Taher Abuelma'atti; Azhar Quddus

    1996-01-01

    A new voltage-mode active-filter with single input and three outputs is presented. The parameters of the proposed filter are programmable and the filter uses grounded capacitors. The proposed circuit can simultaneously realize lowpass, highpass, and bandpass biquadratic filter functions and enjoys low temperature sensitivities.

  2. Analysis of a Three-Level LLC Series Resonant Converter for High- and Wide-Input-Voltage Applications

    Directory of Open Access Journals (Sweden)

    S.Saravanan

    2014-04-01

    Full Text Available In this paper, the analysis of a three-level LLC series resonant converter (TL LLC SRC for high- and wide input-voltage applications is presented. It consists of two half-bridge LLC SRCs in series, sharing a resonant inductor and a transformer. Its main advantages are that the voltage across each switch is clamped at half of the input voltage and that voltage balance is achieved and simple driving signals . Thus it is suitable for high-inputvoltage applications. Based on the results of these analyses, a design example is provided and its validity is confirmed by an experiment involving a prototype converter with an input of 600V and an output of 48 V/20 A.

  3. Prediction of Low-Voltage Tetrafluoromethane Emissions Based on the Operating Conditions of an Aluminium Electrolysis Cell

    Science.gov (United States)

    Dion, Lukas; Kiss, László I.; Poncsák, Sándor; Lagacé, Charles-Luc

    2016-09-01

    Greenhouse gas (GHG) generation is inherent in the production of aluminium by a technology that uses carbon anodes. Most of those GHG are composed of CO2 produced by redox reaction that occurs in the cell. However, a significant fraction of the annual GHG production is composed of perfluorocarbons (PFC) resulting from anode effects (AE). Multiple investigations have shown that tetrafluoromethane (CF4) can be generated under low-voltage conditions in the electrolysis cells, without global anode effect. The aim of this paper is to find a quantitative relationship between monitored cell parameters and the emissions of CF4. To achieve this goal, a predictive algorithm has been developed using seven cell indicators. These indicators are based on the cell voltage, the noise level and other parameters calculated from individual anode current monitoring. The predictive algorithm is structured into three different steps. The first two steps give qualitative information while the third one quantitatively describes the expected CF4 concentration at the duct end of the electrolysis cells. Validations after each step are presented and discussed. Finally, a sensitivity analysis was performed to understand the effect of each indicator on the onset of low-voltage PFC emissions. The standard deviation of individual anode currents was found to be the dominant variable. Cell voltage, noise level, and maximum individual anode current also showed a significant correlation with the presence of CF4 in the output gas of an electrolysis cell.

  4. 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.

  5. Comparative Analysis of PWM Techniques for Three Level Diode Clamped Voltage Source Inverter

    Directory of Open Access Journals (Sweden)

    Zulkifilie Bin Ibrahim

    2014-07-01

    Full Text Available Multilevel inverters are increasingly being used in high-power medium voltage industrial drive applications due to their superior performance compared to conventional two-level inverters. Thre are a number of Pulse width modulation (PWM techniques applied in recent years. The most widely applied PWM techniques are Sine Pulse Width Modulation (SPWM and Space Vector Pulse Width Modulation (SVPWM.  SPWM is the most simple modulation technique that can realize easily in analog circuit.  However, it has some drawbacks such as higher total harmonic distortion (THD, lower effective DC utilization and lower switching frequency. Space vector pulse width modulation (SVPWM is widely used because of their easier digital realization and better DC bus utilization and lower THD. The complexity is due to the difficulty in determining the reference vector location, on times calculation, and switching states selection. This paper presents a simple SVPWM algorithm for diode clamped three level inverters based on standard two-level SVPWM which can easily determine the location of reference vector, calculate the on-times, the selection of switching states. Three level diode clamped inverter (3LDCI using space vector modulation technique has been modeled and simulated using MATLAB/SIMULINK and Origin 6.1 with a passive R-L load that can be extended to any level. Simulation results are presented to verify the proposed SVPWM control in terms of THD. The results are compared with conventional sinusoidal pulse width modulation (SPWM where SVPWM shows better performance than SPWM in terms of THD.

  6. A multi-mode operation control strategy for flexible microgrid based on sliding-mode direct voltage and hierarchical controls.

    Science.gov (United States)

    Zhang, Qinjin; Liu, Yancheng; Zhao, Youtao; Wang, Ning

    2016-03-01

    Multi-mode operation and transient stability are two problems that significantly affect flexible microgrid (MG). This paper proposes a multi-mode operation control strategy for flexible MG based on a three-layer hierarchical structure. The proposed structure is composed of autonomous, cooperative, and scheduling controllers. Autonomous controller is utilized to control the performance of the single micro-source inverter. An adaptive sliding-mode direct voltage loop and an improved droop power loop based on virtual negative impedance are presented respectively to enhance the system disturbance-rejection performance and the power sharing accuracy. Cooperative controller, which is composed of secondary voltage/frequency control and phase synchronization control, is designed to eliminate the voltage/frequency deviations produced by the autonomous controller and prepare for grid connection. Scheduling controller manages the power flow between the MG and the grid. The MG with the improved hierarchical control scheme can achieve seamless transitions from islanded to grid-connected mode and have a good transient performance. In addition the presented work can also optimize the power quality issues and improve the load power sharing accuracy between parallel VSIs. Finally, the transient performance and effectiveness of the proposed control scheme are evaluated by theoretical analysis and simulation results.

  7. Electrooptic Methods for Measurement of Small DC Currents at High Voltage Level

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Beatty, Neville; Skilbreid, Asbjørn Ottar

    1989-01-01

    . The measuring methods can be used both for development and supervision of electrical insulating systems. For DC measurements a system wherein the voltage is applied (across the Pockels cell) not directly but via an electrooptic circuit was developed. This circuit periodically inverts the polarity of the voltage...... fibre to an electrooptic converter. Second, by use of an electronic circuit the measured signal can be converted into a modulated frequency form for transmission along an optical fibre. These systems are described, measurement results are presented and improvements to be made in the future are outlined...... across the cell, effectively applying a square wave voltage with amplitude equal to the DC voltage to be measured. The switching circuit is based around two high voltage transistors TA, TB, with the Pockels cell electrodes being each connected to one of the transistor collectors. The transistor...

  8. Low-power operation using self-timed circuits and adaptive scaling of the supply voltage

    DEFF Research Database (Denmark)

    Nielsen, Lars Skovby; Niessen, C.; Sparsø, Jens

    1994-01-01

    Recent research has demonstrated that for certain types of applications like sampled audio systems, self-timed circuits can achieve very low power consumption, because unused circuit parts automatically turn into a stand-by mode. Additional savings may be obtained by combining the self...... of voltage scaling has been used previously in synchronous circuits, and the contributions of the present paper are: 1) the combination of supply scaling and self-timed circuitry which has some unique advantages, and 2) the thorough analysis of the power savings that are possible using this technique.>......-timed circuits with a mechanism that adaptively adjusts the supply voltage to the smallest possible, while maintaining the performance requirements. This paper describes such a mechanism, analyzes the possible power savings, and presents a demonstrator chip that has been fabricated and tested. The idea...

  9. DC Bus Control of Back-to-Back Connected Two-Level PWM Rectifier-Five-Level NPC Voltage Source Inverter to Torque Ripple Reduction in Induction Motor

    Directory of Open Access Journals (Sweden)

    Abdelkrim Thameur

    2015-01-01

    Full Text Available This paper proposes a regulation method of back-to-back connected two-level PWM rectifier-five-level Voltage Source Inverter (VSI in order to reduce the torque ripple in induction motor. First part is dedicated to the presentation of the feedback control of two-level PWM rectifier. In the second part, five-level Neutral Point Clamped (NPC voltage source inverter balancing DC bus algorithm is presented. A theoretical analysis with a complete simulation of the system is presented to prove the excellent performance of the proposed technique.

  10. Ultra-Low-Voltage Low-Power Bulk-Driven Quasi-Floating-Gate Operational Transconductance Amplifier

    Directory of Open Access Journals (Sweden)

    Ziad Alsibai

    2014-01-01

    Full Text Available A new ultra-low-voltage (LV low-power (LP bulk-driven quasi-floating-gate (BD-QFG operational transconductance amplifier (OTA is presented in this paper. The proposed circuit is designed using 0.18 μm CMOS technology. A supply voltage of ±0.3 V and a quiescent bias current of 5 μA are used. The PSpice simulation result shows that the power consumption of the proposed BD-QFG OTA is 13.4 μW. Thus, the circuit is suitable for low-power applications. In order to confirm that the proposed BD-QFG OTA can be used in analog signal processing, a BD-QFG OTA-based diodeless precision rectifier is designed as an example application. This rectifier employs only two BD-QFG OTAs and consumes only 26.8 μW.

  11. An operational amplifier B1404UD1A-1 in the patch-clamp current-to-voltage converter.

    Science.gov (United States)

    Korzun, A M; Rozinov, S V; Abashin, G I

    1997-01-01

    The applicability of the home-made operational amplifier B1404UD1A-1 in a patch-clamp current-to-voltage converter was analyzed. Its parameters (background noise, input bias current, and gain-bandwidth product) were estimated. Schematic solutions and practical recommendations for the use of this amplifier in a current-to-voltage converter were given. Based on the background noise and frequency parameters of the converter, we found that this device can be used for measuring ion channel currents with a high sensitivity and within a broad frequency range (0.055 pA, to 1 kHz; 0.4 pA, to 10 kHz). An example of the converter application in experiments is given.

  12. Campaign Synergism: Operational Level Combat Power

    Science.gov (United States)

    1990-04-30

    34 See Jominis Te Art of Wa , trans. H.H. Mendell --aid W.P. Craighill (Philade hia, a..: J.B. Li1)pncop and Co., 171.; reprint edition, Westport, C...D:trine," LjfiL 33 (Aug 33): 264-. Epy, Colonel (Ret) Trevor N. "Let’ Get SeriouAbtMliper, Aj 33 (May 83): 18-25. Ellison, Major Gregor W. "Operational Art

  13. Experimental demonstration of strained Si nanowire GAA n-TFETs and inverter operation with complementary TFET logic at low supply voltages

    Science.gov (United States)

    Luong, G. V.; Strangio, S.; Tiedemannn, A.; Lenk, S.; Trellenkamp, S.; Bourdelle, K. K.; Zhao, Q. T.; Mantl, S.

    2016-01-01

    In this work, strained Si (sSi) nanowire array of n-TFETs with gates all around (GAA) yielding ON-currents of 5 μA/μm at a supply voltage Vdd = 0.5 V are presented. Tilted ion implantation with BF2+ into NiSi2 dopant has been used to form a highly doped pocket for the source to channel tunneling junction. These devices indicate sub-threshold slopes (SS) below 60 mV/dec for Id Common analog device characteristics have been determined at Vdd = 0.5 V resulting in a transconductance gm = 24 μS/μm, transconductance efficiency gm/Id = 23 V-1 and the conductance gd = 0.8 μS/μm normalized to the gate width. Based on the good saturation behavior in the output characteristic, an intrinsic gain of 188 is observed. In addition, we present operation of the first experimental sSi GAA NW C-TFET inverter. In spite of ambipolar behavior, the voltage transfer curves (VTC) indicate wide and constant noise margin levels with steep transitions offering a voltage gain of 25 at Vdd = 1 V.

  14. Effects of low level laser therapy and high voltage stimulation on diabetic wound healing

    Directory of Open Access Journals (Sweden)

    María Cristina Sandoval Ortíz

    2014-08-01

    Full Text Available Background: a review of the literature found no clinical studies in which low level laser therapy (LLLT and high voltage pulsed current (HVPC were compared to evaluate their effectiveness in promoting wound healing. Objective: The purpose of this study was compare the effects of LLLT, HVPC and standard wound care (SWC on the healing of diabetic foot ulcers. Methods: randomized controlled clinical trial where diabetic patients were divided in control group (CG treated with SWC; HVPC group received HVPC plus SWC; LLLTgroup, treated with LLLT plus SWC. HVPC was applied 45min, 100pps and 100μs. LLLTparameters were 685nm, 30mW,2J/cm² applied to the wound edges and 1,5J/cm² in the wound bed. All subjects were treated 16 weeks or until the wound closed. The variables were healing, healing proportion, ulcers's characteristics, protective sensation, nerve conduction studies (NCS and quality life. ANCOVA analysis and a Fisher's exact test were applied. Results: Twenty-eight subjects completed the protocol.The healing was reached by 7/9, 8/10 and 6/9 participants of the LLLT, HVPC and CG respectively in the 16th week. There were no statistically significant differences between the groups in the healing proportion, NCS, sensory testing or quality of life (p>0,05. Conclusions: The results of this study did not demonstrated additional effects of LLL or HVPC to the standard wound care (SWC on healing of diabetic ulcers.

  15. Engineering Diffusivity, Band gap and Operating Voltage in Lithium Iron Phosphate through transition metal doping

    OpenAIRE

    Jena, Ajit; Nanda, B. R. K.

    2016-01-01

    Density functional calculations are carried out to understand and tailor the electrochemical profile diffusivity, band gap and open circuit voltage of transition metal doped olivine phosphate LiFe_{1-x}M_{x}PO_{4} (M = V, Cr, Mn, Co and Ni). Diffusion and hence the ionic conductivity is studied by calculating the activation barrier, V_{act}, experienced by the diffusing Li^{+} ion. We show that the effect of dopants on diffusion is both site dependent and short ranged and thereby it paves way...

  16. Note: Repetitive operation of the capacitor bank of the low-voltage miniature plasma focus at 50 Hz

    Science.gov (United States)

    Shukla, Rohit; Shyam, Anurag

    2013-10-01

    We have already reported the low-voltage operation of a plasma focus describing the operation of plasma focus at 4.2 kV which proposes possibility of making a repetitive system using compact driving source. Another recent article describes that the same capacitor-bank can drive the plasma focus for a measured ˜5 × 104 neutrons per shot at 5 kV and 59 kA current. In the present work, repetitive operation of the capacitor-bank of plasma focus is done and that too is being reported at a very high repetition rate of 50 Hz using very simple scheme of charging and triggering the bank. The bank is continuously discharged to burst duration of 20 s in this configuration admeasuring a thousand shots.

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

    Directory of Open Access Journals (Sweden)

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

    2010-01-01

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

  18. Operating Circuit Fault Diagnosis of High Voltage Circuit Breaker%高压断路器操作回路的故障诊断

    Institute of Scientific and Technical Information of China (English)

    赵红宇; 龙树峰

    2015-01-01

    This paper analyzes and studies the fault diagnosis operation requirements of high voltage circuit breaker operation circuit and the fault diagnosis method of high voltage circuit breaker.%本文对高压断路器操作回路的故障诊断操作要求和高压断路器操作回路的故障诊断方法进行了分析和研究。

  19. Medium Voltage Three-level Converters for the Grid Connection of aMulti-MW Wind Turbine

    DEFF Research Database (Denmark)

    Senturk, Osman Selcuk; Helle, Lars; Munk-Nielsen, Stig

    2009-01-01

    Three-level (3L) neutral point clamped (NPC), flying capacitor (FC), and H-bridge (HB) voltage source converters (VSCs) as a grid-side full-scale medium voltage (MV) converter are modeled, controlled, and simulated for the grid connection of a hypothetical 6MW wind turbine. Via the converter...... connection circuit (without capacitive switching ripple filters), the 3L-HB-VSC is expected to be superior with respect to power density and reliability over the 3L-NPC- and -FC-VSCs....

  20. Control Method of Three-level Neutral-point-clamped Inverter Based on Voltage Vector Diagram Partition

    Institute of Scientific and Technical Information of China (English)

    SONG Wen-xiang; YAO Gang; CHEN Chen; CHEN Guo-cheng

    2008-01-01

    A new modulation approach was presented for the control of neutral-point (NP) voltage variation in the three-level NP-clamped voltage source inverter, and the average NP current model was established based on vector diagram partition. Thus, theory base was built for balancing control of NP potential. Theoretical analysis and experimental results indicate that the proposed method for NP balancing control vector synthesizing concept based can make the average NP current zero, and do not influence NP potential within every sample period. The effectiveness of proposed research approach was verified by simulative and experimental results.

  1. New Modulation Strategy to Balance the Neutral-Point Voltage for Three-Level Neutral-Clamped Inverter Systems

    DEFF Research Database (Denmark)

    Choi, Uimin; Lee, June-Seok; Lee, Kyo-Beum

    2014-01-01

    This paper proposes a new modulation strategy that balances the neutral-point voltage for three-level neutral-clamped inverter systems. The proposed modulation replaces the P-type or N-type small switching states with other switching states that do not affect the neutral-point voltage. The zero...... and medium switching states are employed to help the neutral-point voltage balancing. This method little bit increases the switching events and output total harmonic distortion. However, this method has a strong balancing ability at all regions. Further, it is very simple to implement in both space vector...... modulation and carrier-based PWM methods. Simulation and experimental results verify the validity and feasibility of the proposed new modulation strategy....

  2. Modelling and control of a seven level NPC voltage source inverter. Application to high power induction machine drive

    Energy Technology Data Exchange (ETDEWEB)

    Gheraia, H.; Berkouk, E.M. [ENP, Alger (Algeria). Lab. de Commande des Processus; Manesse, G. [CNAM-Paris (France). Lab. d' Electricite Industrielle

    2001-08-01

    In this paper, we study a new kind of continuous-alternating converters: a seven-level neutral point clamping (NPC) voltage source inverter (VSI). We propose this inverter for applications in high voltage and high power fields. In the first part, we develop the knowledge and the control models of this inverter using the connections functions of the semi-conductors. After that, we present two pulse width modulation (PWM) algorithms to control this converter using its control model. We propose these algorithms for digital implementation. This multilevel inverter is associated to the induction machine. The performances obtained are full of promise to use it in the high voltage and high power fields of electrical traction. (orig.)

  3. The Calculation of Unbalanced Voltage on the tertiary bus of a single phase auto transformer in case of Parallel Operation with Different Manufacturer

    Energy Technology Data Exchange (ETDEWEB)

    Shim, E.B.; Woo, J.W.; Kwak, J.S. [Korea Electric Power Research Institute (Korea); Joe, S.H.; Hur, Y.H. [KEPCO (Korea); Han, S.O. [Chungnam University (Korea)

    2001-07-01

    This paper described the unbalanced voltage on the tertiary bus of a single phase auto transformer in the case of parallel operation with different manufacturer at each phase. The unbalanced capacitances between primary to secondary winding, secondary to tertiary winding and primary to tertiary winding makes unbalanced bus voltage in the tertiary bus side. The unbalanced voltage let the surge arrester to operate in the power frequency range, and it causes the arrester to burn out. The failure of the arrester at one phase makes line to ground fault, which lead to the surge arrester failure of the other two phase on the tertiary bus. (author). 3 refs., 10 figs., 2 tabs.

  4. The effect of applied control strategy on the current-voltage correlation of a solid oxide fuel cell stack during dynamic operation

    Directory of Open Access Journals (Sweden)

    Szmyd Janusz S.

    2014-09-01

    Full Text Available This paper discusses the transient characteristics of the planar type SOFC cell stack, of which the standard output is 300 W. The transient response of the voltage to the manipulation of an electric current was investigated. The effects of the response and of the operating condition determined by the operating temperature of the stack were studied by mapping a current-voltage (I-V correlation. The current-based fuel control (CBFC was adopted for keeping the fuel utilization factor at constant while the value of the electric current was ramped at the constant rate. The present experimental study shows that the transient characteristics of the cell voltage are determined by primarily the operating temperature caused by the manipulation of the current. Particularly, the slope of the I-V curve and the overshoot found on the voltage was remarkably influenced by the operating temperature. The different values of the fuel utilization factor influence the height of the settled voltages. The CBFC has significance in determining the slope of the I-V characteristic, but the different values ofthe fuel utilization factor does not affect the slope as the operating temperature does. The CBFC essentially does not alter the amplitude of the overshoot on the voltage response, since this is dominated by the operating temperature and its change is caused by manipulating the current.

  5. Empirical Verification of Fault Models for FPGAs Operating in the Subcritical Voltage Region

    DEFF Research Database (Denmark)

    Birklykke, Alex Aaen; Koch, Peter; Prasad, Ramjee

    2013-01-01

    fault models might provide insight that would allow subcritical scaling by changing digital design practices or by simply accepting errors if possible. To facilitate further work in this direction, we present probabilistic error models that allow us to link error behavior with statistical properties...... of the binary signals, and based on a two-FPGA setup we experimentally verify the correctness of candidate models. For all experiments, the observed error rates exhibit a polynomial dependency on outcome probability of the binary inputs, which corresponds to the behavior predicted by the proposed timing error...... model. Furthermore, our results show that the fault mechanism is fully deterministic - mimicking temporary stuck-at errors. As a result, given knowledge about a given signal, errors are fully predictable in the subcritical voltage region....

  6. Extended-gate-type IGZO electric-double-layer TFT immunosensor with high sensitivity and low operation voltage

    Science.gov (United States)

    Liang, Lingyan; Zhang, Shengnan; Wu, Weihua; Zhu, Liqiang; Xiao, Hui; Liu, Yanghui; Zhang, Hongliang; Javaid, Kashif; Cao, Hongtao

    2016-10-01

    An immunosensor is proposed based on the indium-gallium-zinc-oxide (IGZO) electric-double-layer thin-film transistor (EDL TFT) with a separating extended gate. The IGZO EDL TFT has a field-effect mobility of 24.5 cm2 V-1 s-1 and an operation voltage less than 1.5 V. The sensors exhibit the linear current response to label-free target immune molecule in the concentrations ranging from 1.6 to 368 × 10-15 g/ml with a detection limit of 1.6 × 10-15 g/ml (0.01 fM) under an ultralow operation voltage of 0.5 V. The IGZO TFT component demonstrates a consecutive assay stability and recyclability due to the unique structure with the separating extended gate. With the excellent electrical properties and the potential for plug-in-card-type multifunctional sensing, extended-gate-type IGZO EDL TFTs can be promising candidates for the development of a label-free biosensor for public health applications.

  7. Thermal Optimized Operation of the Single-Phase Full-Bridge PV Inverter under Low Voltage Ride-Through Mode

    DEFF Research Database (Denmark)

    Wang, Huai; Yang, Yongheng; Blaabjerg, Frede

    2013-01-01

    The efficiency of 98% has been reported on transformer-less photovoltaic (PV) inverters and the penetration of grid-connected PV systems is booming as well. In the future, the PV systems are expected to contribute to the grid stability by means of low voltage ride-through operation and grid support....... At the same time, the target of a long service time (25 years or more) imposes new challenges to grid-connected transformer-less PV systems. Achieving more reliable PV inverters is of intense interest in recent research. As one of the most critical stresses that induce failures, the thermal stresses...... on the power devices of a single-phase full-bridge PV inverter are analyzed in different operational modes in this paper. The low voltage grid condition is specially taken into account in this paper. The analysis is demonstrated by a 3 kW single-phase full-bridge grid-connected PV system by simulations...

  8. Rectifying structure with high voltage operation based on CuBO{sub 2} as an UV photocatalyst

    Energy Technology Data Exchange (ETDEWEB)

    Soylu, M., E-mail: soylum74@yahoo.com [Department of Physics, Faculty of Sciences and Arts, Bingol University, Bingol (Turkey); Al-Ghamdi, Ahmed A. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Omran, Saad Bin [Department of Physics and Astronomy, College of Science, King Saud University, Riyadh (Saudi Arabia); Yakuphanoglu, F. [Department of Physics, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia); Department of Physics, Faculty of Science, Firat University, Elazig 23169 (Turkey)

    2014-12-25

    Highlight: • We have fabricated nanostructured CuBO{sub 2} by spin coating on the p-Si. • CuBO{sub 2}/p-Si diode is a new rectifying structure with photosensing. • The photocurrent in the reverse bias voltage is increased by increasing photo-illumination intensity. • CuBO{sub 2}/p-Si/Al diode is a candidate for producing high tension protection circuit. - Abstract: CuBO{sub 2}/p-Si diode is a new rectifying structure with photosensing, which is a candidate for producing high voltage protection circuit in electronic application. It has been seen that the photocurrent in the reverse bias I–V characteristic is strongly increased by photo-illumination. It is believed that the combination of thin CuBO{sub 2} layer and p-Si will provide high voltage protection level, which does not exist for conventional Si diodes. The capacitance and conductance–voltage characteristics were measured at various frequencies. The results indicate that the electrical parameters of CuBO{sub 2}/p-Si diode are affected by the series resistance and interface states. The optical properties of the CuBO{sub 2} thin film were analyzed by UV–vis–NIR spectrophotometry and FTIR studies. The optical band gap of the CuBO{sub 2} is located in the ultraviolet (UV) range. In this spectral range, the B-O-B bonds and relationship between Cu{sup 2+}–O are confirmed.

  9. Behavior of deep level defects on voltage-induced stress of Cu(In,Ga)Se{sub 2} solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, D.W.; Cho, S.E. [Department of Physics and Semiconductor Science, Dongguk University, Seoul (Korea, Republic of); Jeong, J.H. [Solar Cell Center, Korea Institute of Science and Technology, Seoul (Korea, Republic of); Cho, H.Y., E-mail: hycho@dongguk.edu [Department of Physics and Semiconductor Science, Dongguk University, Seoul (Korea, Republic of)

    2015-05-01

    The behavior of deep level defects by a voltage-induced stress for CuInGaSe{sub 2} (CIGS) solar cells has been investigated. CIGS solar cells were used with standard structures which are Al-doped ZnO/i-ZnO/CdS/CIGSe{sub 2}/Mo on soda lime glass, and that resulted in conversion efficiencies as high as 16%. The samples with the same structure were isothermally stressed at 100 °C under the reverse voltages. The voltage-induced stressing in CIGS samples causes a decrease in the carrier density and conversion efficiency. To investigate the behavior of deep level defects in the stressed CIGS cells, photo-induced current transient spectroscopy was utilized, and normally 3 deep level defects (including 2 hole traps and 1 electron trap) were found to be located at 0.18 eV and 0.29 eV above the valence band maximum (and 0.36 eV below the conduction band). In voltage-induced cells, especially, it was found that the decrease of the hole carrier density could be responsible for the increase of the 0.29 eV defect, which is known to be observed in less efficient CIGS solar cells. And the carrier density and the defects are reversible at least to a large extent by resting at room-temperature without the bias voltage. From optical capture kinetics in photo-induced current transient spectroscopy measurement, the types of defects could be distinguished into the isolated point defect and the extended defect. In this work, it is suggested that the increase of the 0.29 eV defect by voltage-induced stress could be due to electrical activation accompanied by a loss of positive ion species and the activated defect gives rise to reduction of the carrier density. - Highlights: • We investigated behavior of deep level defects by voltage-induced stress. • Defect generation could affect the decrease of the conversion efficiency of cells. • Defect generation could be electrically activated by a loss of positive ion species. • Type of defects could be studied with models of point defects

  10. Engineering Diffusivity and Operating Voltage in Lithium Iron Phosphate through Transition-Metal Doping

    Science.gov (United States)

    Jena, Ajit; Nanda, B. R. K.

    2017-03-01

    Density-functional calculations are carried out to understand and tailor the electrochemical profile—diffusivity, band gap, and open-circuit voltage—of transition-metal-doped olivine phosphate: LiFe1 -xMxPO4 (M =V , Cr, Mn, Co, and Ni). Diffusion and, hence, the ionic conductivity is studied by calculating the activation barrier Vact experienced by the diffusing Li+ ion. We show that the effect of dopants on diffusion is both site dependent and short ranged, and thereby it paves ways for microscopic control of ionic conductivity via selective dopants in olivine phosphates. Dopants with lower-valence electrons (LVEs) compared to Fe repel the Li+ ion to facilitate its outward diffusion, whereas higher-valence-electron (HVE) dopants attract the Li+ ion to facilitate the inward diffusion. From the electronic structure calculation, we establish that irrespective of the dopant M , except Mn, the band gap is reduced since the M d states always lie within the pure band gap. Atomically localized d states of HVE dopants lie above the Fermi energy and that of LVE lie below it. Half-filled Mn d states undergo a large spin-exchange split to bury the dopant states in the valence and conduction bands of the pristine system, and, in turn, the band gap remains unchanged in LiFe1 -xMnxPO4 . Baring Mn, the open-circuit voltage increases with HVE dopants and decreases with LVE dopants.

  11. Three-Level Inverters with Common-Mode Voltage Cancellation Based on Synchronous Pulsewidth Modulation

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede

    2002-01-01

    of the voltage waveforms during the whole control range including overmodulation. Continuous, discontinuous and "direct-direct" schemes of synchronous PWM with both algebraic and trigonometric control functions have been analysed and compared. Simulations give the behaviour of the proposed methods and show some...

  12. Synchronised PWM Schemes for Three-level Inverters with Zero Common-mode Voltage

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede

    2002-01-01

    PWM with synchronous smooth pulses-ratio changing and a quarter-wave symmetry of the voltage waveforms. Three basic versions of both algebraic and trigonometric synchronised PWM have been analysed. Simulations give the behaviour of the proposed methods and show some advantage of synchronised PWM...

  13. Synchronised PWM Schemes for Three-level Inverters with Zero Common-mode Voltage

    DEFF Research Database (Denmark)

    Oleschuk, Valentin; Blaabjerg, Frede

    2002-01-01

    PWM with synchronous smooth pulses-ratio changing and a quarter-wave symmetry of the voltage waveforms. Three basic versions of both algebraic and trigonometric synchronised PWM have been analysed. Simulations give the behaviour of the proposed methods and show some advantage of synchronised PWM...

  14. Harmonic elimination technique for a single-phase multilevel converter with unequal DC link voltage levels

    DEFF Research Database (Denmark)

    Ghasemi, N.; Zare, F.; Boora, A.A.

    2012-01-01

    on the output voltage quality by reducing its total harmonic distortion, which must take into consideration for some applications such as uninterruptable power supply, motor drive systems and piezoelectric transducer excitation. In order to verify the proposed modulation technique, MATLAB simulations...

  15. A novel bioelectrochemical BOD sensor operating with voltage input.

    Science.gov (United States)

    Modin, Oskar; Wilén, Britt-Marie

    2012-11-15

    Biochemical oxygen demand (BOD) is a measure of biodegradable compounds in water and is, for example, a common parameter to design and assess the performance of wastewater treatment plants. The conventional method to measure BOD is time consuming (5 or 7 days) and requires trained personnel. Bioelectrochemical BOD sensors designed as microbial fuel cells (MFCs), which are systems where bacteria convert organic matter into an electrical current, have emerged as an alternative to the conventional technique. In this study, a new type of bioelectrochemical BOD sensor with features that overcome some of the limitations of current MFC-type designs was developed: (1) An external voltage was applied to overcome internal resistances and allow bacteria to generate current at their full capacity, and (2) the ion exchange membrane was omitted to avoid pH shifts that would otherwise limit the applicability of the sensor for wastewaters with low alkalinity. The sensor was calibrated with an aerated nutrient medium containing acetate as the BOD source. Linear correlation (R(2) = 0.97) with charge was obtained for BOD concentrations ranging from 32 to 1280 mg/L in a reaction time of 20 h. Lowering the reaction time to 5 h resulted in lowering the measurable BOD concentration range to 320 mg/L (R(2) = 0.99). Propionate, glucose, and ethanol could also be analyzed by the sensor that was acclimated to acetate. The study demonstrates a way to design more robust and simple bioelectrochemical BOD sensors that do not suffer from the usual limitations of MFCs (high internal resistance and pH shifts).

  16. Investigation of Low Discharge Voltage Hall Thruster Operating Modes and Ionization Processes

    Science.gov (United States)

    2009-08-14

    a null-type, inverted pendulum thrust stand based on the NASA GRC design.11 The thruster is shown mounted to the thrust stand in Figure 3... cloud of neutral propellant. This thruster operation was studied in detail using the far-field diagnostics and characterized with variations in

  17. A CAD investigation of metal-overhang on multiple guard ring design for high voltage operation of Si sensors

    Science.gov (United States)

    Bhardwaj, Ashutosh; Ranjan, Kirti; Namrata; Chatterji, Sudeep; Srivastava, Ajay K.; Shivpuri, R. K.

    2002-12-01

    The extension of Si detectors to the next generation high-energy physics experiments such as large hadron collider implies a reliable operation in high radiation environment which is by far the main technological challenge for these detectors. Multiple field limiting ring systems are well established as a means of protecting diffused junction from high voltage premature breakdown. Also, a spread of the Al metallization over the inter-cathodic field oxide sensibly lowers the electric field at the junction edges, thus, allowing for higher breakdown voltages. The purpose of this work is to combine the positive aspects of these two termination techniques with the aim of defining layouts and technological solutions suitable for the use of Si detectors in adverse radiation environment. An important feature is the potential distribution in the multi-guard ring structure, which depends on the bulk doping concentration, the oxide charge, the size of the gap between guard rings and the metal-overhang design. A systematic investigation on the breakdown performance is done by varying the physical and geometrical parameters such as width of overhang, guard ring spacing, junction depth and oxide charge. CAD tools are used for evaluating potential and electric field distributions within the device.

  18. Low voltage logic circuits exploiting gate level dynamic body biasing in 28 nm UTBB FD-SOI

    Science.gov (United States)

    Taco, Ramiro; Levi, Itamar; Lanuzza, Marco; Fish, Alexander

    2016-03-01

    In this paper, the recently proposed gate level body bias (GLBB) technique is evaluated for low voltage logic design in state-of-the-art 28 nm ultra-thin body and box (UTBB) fully-depleted silicon-on-insulator (FD-SOI) technology. The inherent benefits of the low-granularity body-bias control, provided by the GLBB approach, are emphasized by the efficiency of forward body bias (FBB) in the FD-SOI technology. In addition, the possibility to integrate PMOS and NMOS devices into a single common well configuration allows significant area reduction, as compared to an equivalent triple well implementation. Some arithmetic circuits were designed using GLBB approach and compared to their conventional CMOS and DTMOS counterparts under different running conditions at low voltage regime. Simulation results shows that, for 300 mV of supply voltage, a 4 × 4-bit GLBB Baugh Wooley multiplier allows performance improvement of about 30% and area reduction of about 35%, while maintaining low energy consumption as compared to the conventional CMOS ⧹ DTMOS solutions. Performance and energy benefits are maintained over a wide range of process-voltage-temperature (PVT) variations.

  19. Influence of disturbances on bacteria level in an operating room

    DEFF Research Database (Denmark)

    Brohus, Henrik; Hyldig, Mikkel; Kamper, Simon

    2008-01-01

    In operating rooms great effort is manifested to reduce the bacteria level in order to decrease the risk of infections. The main source of bacteria is the staff and the patient, thus, the resulting bacteria concentration is roughly speaking a combination of the ventilation system and the emission...... from the occupants. This study investigates the influence of two main disturbances in an operating room namely the door opening during the operation and the activity level of the staff. It is found that the frequent door opening in this case does not cause significant transport of air from outside...... the operating room to the wound area of the patient. However, a significant influence of the activity level on the bacteria emission and concentration is found. Counting the number of persons in an operating room to estimate the bacteria source strength is not sufficient, the corresponding activity level must...

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

    Directory of Open Access Journals (Sweden)

    Parol Mirosław

    2016-03-01

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

  1. Gaussian translation operator for Multi-Level Fast Multipole Method

    DEFF Research Database (Denmark)

    Borries, Oscar Peter; Hansen, Per Christian; Sorensen, Stig B.

    2014-01-01

    Results using a new translation operator for the Multi-Level Fast Multipole Method are presented. Based on Gaussian beams, the translation operator allows a significant portion of the plane-wave directions to be neglected, resulting in a much faster translation step.......Results using a new translation operator for the Multi-Level Fast Multipole Method are presented. Based on Gaussian beams, the translation operator allows a significant portion of the plane-wave directions to be neglected, resulting in a much faster translation step....

  2. Performance, high voltage operation and radiation hardness of full-size ATLAS charge division silicon detectors with LHC electronics

    Science.gov (United States)

    Allport, P. P.; Booth, P. S. L.; Carter, J. R.; Goodrick, M. J.; Green, C.; Greenall, A.; Hanlon, M.; Hill, J. C.; Jackson, J. N.; Jones, T. J.; Martí i García, S.; Munday, D. J.; Murray, W.; Richardson, J. D.; Robinson, D.; Sheridan, A. E.; Smith, N. A.; Tyndel, M.; Wyllie, K.

    1998-02-01

    ATLAS silicon detectors designed for charge division read-out were produced during 1995 and have been extensively studied both in the laboratory and test beam at the CERN SPS. Data have been taken with the analogue read-out FELIX-128 chip and studies simulating other read-out architectures under consideration by ATLAS have been performed. To evaluate survival in the harsh environment of the LHC, detectors have been tested to high voltage, both before and after radiation damage by protons exceeding the expected charged hadron dose after 10 years of LHC operation. These tests have all employed analogue read-out to be sensitive to changes in noise and charge collection efficiency as a function of the detector damage.

  3. A novel biological activity of praziquantel requiring voltage-operated Ca2+ channel beta subunits: subversion of flatworm regenerative polarity.

    Directory of Open Access Journals (Sweden)

    Taisaku Nogi

    Full Text Available BACKGROUND: Approximately 200 million people worldwide harbour parasitic flatworm infections that cause schistosomiasis. A single drug-praziquantel (PZQ-has served as the mainstay pharmacotherapy for schistosome infections since the 1980s. However, the relevant in vivo target(s of praziquantel remain undefined. METHODS AND FINDINGS: Here, we provide fresh perspective on the molecular basis of praziquantel efficacy in vivo consequent to the discovery of a remarkable action of PZQ on regeneration in a species of free-living flatworm (Dugesia japonica. Specifically, PZQ caused a robust (100% penetrance and complete duplication of the entire anterior-posterior axis during flatworm regeneration to yield two-headed organisms with duplicated, integrated central nervous and organ systems. Exploiting this phenotype as a readout for proteins impacting praziquantel efficacy, we demonstrate that PZQ-evoked bipolarity was selectively ablated by in vivo RNAi of voltage-operated calcium channel (VOCC beta subunits, but not by knockdown of a VOCC alpha subunit. At higher doses of PZQ, knockdown of VOCC beta subunits also conferred resistance to PZQ in lethality assays. CONCLUSIONS: This study identifies a new biological activity of the antischistosomal drug praziquantel on regenerative polarity in a species of free-living flatworm. Ablation of the bipolar regenerative phenotype evoked by PZQ via in vivo RNAi of VOCC beta subunits provides the first genetic evidence implicating a molecular target crucial for in vivo PZQ activity and supports the 'VOCC hypothesis' of PZQ efficacy. Further, in terms of regenerative biology and Ca(2+ signaling, these data highlight a novel role for voltage-operated Ca(2+ entry in regulating in vivo stem cell differentiation and regenerative patterning.

  4. An ultra-low voltage high gain operational transconductance amplifier for biomedical applications

    OpenAIRE

    Bautista, F.; Martınez, S.O.; Dieck, G.; Rossetto, O.

    2007-01-01

    special issue in one of the Eurasip journals (Hindawi Publishing Corporation); International audience; A novel differential-input single-output Operational Transconductance Amplifier (OTA) is presented in this paper. The topology proposed consists of an input stage based on a folded cascoded amplifier, and an output stage based on a current source amplifier and a bulk-driven current mirror. The simulations show that the amplifier has a 1.94¹W power dissipation, 92dB open-loop DC gain, a unit ...

  5. Continuous wave operation of distributed feedback quantum cascade lasers with low threshold voltage and low power consumption

    Science.gov (United States)

    Xie, Feng; Caneau, Catherine; LeBlanc, Herve P.; Coleman, Sean; Hughes, Lawrence C.; Zah, Chung-en

    2012-03-01

    We demonstrated the room temperature continuous wave (CW) operation of mid-infrared distributed feedback (DFB) quantum cascade lasers (QCLs) made of strain balanced GaInAs/AlInAs material on InP substrates for sensing CO2 isotope and N2O gas for potential applications that need battery powered portable devices in a sensor network. For the former device at 4.35 μm wavelength, we demonstrated a low threshold voltage of less than 8 V for battery operation and a near circular far field pattern with small divergent angles of 33 by 28 degrees full width at half maximum (FWHM) in vertical and horizontal directions, respectively, for easy collimation. For the latter device at 4.5 μm wavelength, we demonstrated a low CW threshold power consumption of 0.7 W at 20 °C. A side mode suppression ratio (SMSR) of 30 dB was achieved within the whole operating current and temperature ranges for both lasers.

  6. General Consideration of Measuring System for Operational Test of Thyristor Valves of Ultra High Voltage DC Power Transmission

    Institute of Scientific and Technical Information of China (English)

    ZHOU Hui-gao; XU Fan; ZHANG Chang-chun; HU Zhi-long; LIU Pu; HUANG Xi-dong; WAN Gan; DING Qian

    2011-01-01

    Thyristor valve is one of the key equipments for ultra high voltage direct current (UHVDC)power transmission projects.Before being installed on site,they need to be tested in a laboratory in order to verify their operational performance to satisfy the technical specification of project related.Test facilities for operational tests of thyristor valves are supposed to enable to undertake more severe electrical stresses than those being applied in the thyristor valves under test (test objects).On the other hand,the stresses applied into the test objects are neither higher nor lower than specified by the specification,because inappropriate stresses applied would result in incorrect evaluation of performance on the test objects,more seriously,would cuase the damage of test objects with expensive cost losing.Generally,the process of operational tests is complicated and performed in a complex synthetic test circuit(hereafter as STC),where there are a lot of sensors used for measuring,monitoring and protection on line to ensure that the test circuit functions in good condition.Therefore,the measuring systems embedded play a core role in STC,acting like "eyes".Based on the first project of building up a STC in China,experience of planning measuring systems is summarized so as to be referenced by related engineers.

  7. Spin Hamilton Operators, Symmetry Breaking, Energy Level Crossing and Entanglement

    OpenAIRE

    Steeb, Willi-Hans; Hardy, Yorick; de Greef, Jacqueline

    2011-01-01

    We study finite-dimensional product Hilbert spaces, coupled spin systems, entanglement and energy level crossing. The Hamilton operators are based on the Pauli group. We show that swapping the interacting term can lead from unentangled eigenstates to entangled eigenstates and from an energy spectrum with energy level crossing to avoided energy level crossing.

  8. Cyberspace at the Operational Level: Warfighting In All Five Domains

    Science.gov (United States)

    2016-05-13

    fires platforms useless, falsify intelligence, deny positional awareness, and bypass force protection measures. This exploitation of cyberspace...domains to achieve operational objectives. NOTE: See reading NWC 2062Y, Enclosure 1, for detailed guidance on paper construction and...at the operational level. Potential enemies will strive to use cyberspace to deny command and control, block sustainment efforts, render fires

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

    OpenAIRE

    Masaharu Kobayashi; Toshiro Hiramoto

    2016-01-01

    Internet-of-Things (IoT) technologies require a new energy-efficient transistor which operates at ultralow voltage and ultralow power for sensor node devices employing energy-harvesting techniques as power supply. In this paper, a practical device design guideline for low voltage operation of steep-slope negative-capacitance field-effect-transistors (NCFETs) operating at sub-0.2V supply voltage is investigated regarding operation speed, material requirement and energy efficiency in the case o...

  10. Compound control method of neutral point voltage of three level NPC inverter based on the vector method of virtual space and hysteresis control

    Science.gov (United States)

    Yang, Fengping; Xiao, Fangfei

    2017-03-01

    Current control methods include hardware control and software control corresponding to the inherent unbalance problem of neutral point voltage in three level NPC inverter. The hardware control is rarely used due to its high cost. In this paper, a new compound control method has been presented based on the vector method of virtual space and traditional hysteresis control of neutral point voltage, which can make up the shortcoming of the virtual control without the feedback control system of neutral point voltage and the blind area of hysteresis control and control the deviation and wave of neutral point voltage. The accuracy of this method has been demonstrated by simulation.

  11. 基于低压高精度运放的带隙基准电压源设计%Design of Band-Gap Voltage Reference Based on Low Voltage and High Precision Operational Amplifier

    Institute of Scientific and Technical Information of China (English)

    黄静; 唐路; 陈庆; 施敏

    2012-01-01

    基于传统带隙基准源的电路结构,采用电平移位的折叠共源共栅输入级和甲乙类互补推挽共源输出级改进了其运算放大器的性能,并结合一阶温度补偿、电流负反馈技术设计了一款低温度系数、高电源电压抑制比(PSRR)的低压基准电压源.利用华润上华公司的CSMC 0.35 μm标准CMOS工艺对电路进行了Hspice仿真,该带隙基准源电路的电源工作范围为1.5~2.3 V,输出基准电压为(600±0.2) mV;工作温度为10 ~130 ℃,输出电压仅变化8μV,温度系数为1.86×10-6/℃,低频时PSRR为- 72 dB.实际流片进行测试,结果表明达到了预期结果.%A low voltage band-gap voltage reference with good temperature characteristics and high power supply rejection ratio ( PSRR) was designed by temperature compensation, current negative feedback and high performance operational amplifier technology. The improved operational amplifier, the core circuit of the voltage reference, was constituted with a folded-cascade input and a common-source output gain stage. This band-gap voltage reference was simulated by Hspice software with CSMC 0. 35 (xm CMOS process technology model. The results show that the output voltage of voltage reference is (600 ±0. 2) mV with the power operating from 1.5 V to 2. 3 V. The temperature coefficient is 1. 86 × 10-6/℃ with the temperature range from 10 ℃ to 130 ℃ and the output voltage only change is 8 μV. And the PSRR is -72 dB at low frequency. Test results are very consistent with the expected results.

  12. 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.

  13. Reduced operating voltage and grey-to-grey response time in a vertically aligned liquid crystal display using a mixture of two polyimide alignment materials

    Science.gov (United States)

    Lee, Ji-Hoon; Choi, Young Eun; Lee, Jun Hee; Lee, Byeong Hoon; Song, Won Il; Jeong, Kwang-Un; Lee, Gi-Dong; Lee, Seung Hee

    2013-12-01

    We proposed a method to reduce the operating voltage and the grey-to-grey switching time of a vertically aligned liquid crystal display using a mixture of planar and vertical polyimide alignment materials. The surface anchoring energy of the two-polyimide mixture was smaller than that of the pure vertical polyimide and consequently, liquid crystal molecules were easily switched to a planar state with an electric field, resulting in a greater maximum retardation than that of the pure polyimide at the same applied voltage. Rising time was also significantly reduced due to the suppressed optical bouncing effect in the mixed planar polyimide, and the decaying time showed negligible change. With the proposed approach, we can reduce the cell gap to obtain half-wave retardation allowing for faster response time while keeping a low operating voltage.

  14. Direct Power Control for Three-Phase Two-Level Voltage-Source Rectifiers Based on Extended-State Observation

    DEFF Research Database (Denmark)

    Song, Zhanfeng; Tian, Yanjun; Yan, Zhuo

    2016-01-01

    characteristic is highly dynamic behaviors, the proposed control strategy can present comparably enhanced transient performance. Furthermore, excellent steady-state power performance can also be observed when the proposed control scheme is adopted. In addition, another attractive feature lies in its robust......This paper proposed a direct power control strategy for three-phase two-level voltage-source rectifiers based on extended-state observation. Active and reactive powers are directly regulated in the stationary reference frame. Similar to the family of predictive controllers whose inherent...... control strategy, the vector-oriented control scheme and the proposed strategy, which demonstrate the superiority of the proposed scheme....

  15. A Three-Level Quasi-Two-Stage Single-Phase PFC Converter with Flexible Output Voltage and Improved Conversion Efficiency

    DEFF Research Database (Denmark)

    Tang, Yi; Zhu, Dexuan; Jin, Chi

    2015-01-01

    voltage will be fairly constant. The dynamic response of this regulation loop is also very fast and the system is therefore insensitive to external disturbances. Both simulation and experimental results are presented to show the effectiveness of this converter as well as its efficiency improvement against......This paper presents a three-level quasi-two-stage single-phase power factor correction (PFC) converter that has flexible output voltage and improved conversion efficiency. The proposed PFC converter features sinusoidal input current, three-level output characteristic, and a wide range of output dc...... voltages, and it will be very suitable for high-power applications where the output voltage can be either lower or higher than the peak ac input voltage, e.g., plug-in hybrid electric vehicle charging systems. Moreover, the involved dc/dc buck conversion stage may only need to process partial input power...

  16. Operating and Loading Conditions of a Three-Level Neutral-Point-Clamped Wind Power Converter Under Various Grid Faults

    DEFF Research Database (Denmark)

    Ma, Ke; Liserre, Marco; Blaabjerg, Frede

    2014-01-01

    In order to fulfill the growing demands from the grid side, full-scale power converters are becoming popular in the wind turbine system. The low-voltage ride-through (LVRT) requirements may not only cause control problems but also result in overstressed components for the power converter. However......, the thermal loading of the wind power converter under various grid faults is still not yet clarified, particularly at megawatt power level. In this paper, the impacts by three types of grid faults to a three-level neutral-point-clamped (3L-NPC) wind power converter in terms of operating and loading conditions...... are analytically solved and simulated. It has been found that the operating and loading conditions of the converter under LVRT strongly depend on the types/severity values of grid voltage dips and also the chosen control algorithms. The thermal distribution among the three phases of the converter may be quite...

  17. 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.

  18. Golli Myelin Basic Proteins Modulate Voltage-Operated Ca(++) Influx and Development in Cortical and Hippocampal Neurons.

    Science.gov (United States)

    Vt, Cheli; DA, Santiago González; V, Spreuer; V, Handley; At, Campagnoni; Pm, Paez

    2016-10-01

    The golli proteins, products of the myelin basic protein gene, are widely expressed in oligodendrocyte progenitor cells and neurons during the postnatal development of the brain. While golli appears to be important for oligodendrocyte migration and differentiation, its function in neuronal development is completely unknown. We have found that golli proteins function as new and novel modulators of voltage-operated Ca(++) channels (VOCCs) in neurons. In vitro, golli knock-out (KO) neurons exhibit decreased Ca(++) influx after plasma membrane depolarization and a substantial maturational delay. Increased expression of golli proteins enhances L-type Ca(++) entry and processes outgrowth in cortical neurons, and pharmacological activation of L-type Ca(++) channels stimulates maturation and prevents cell death in golli-KO neurons. In situ, Ca(++) influx mediated by L-type VOCCs was significantly decreased in cortical and hippocampal neurons of the golli-KO brain. These Ca(++) alterations affect cortical and hippocampal development and the proliferation and survival of neural progenitor cells during the postnatal development of the golli-KO brain. The CA1/3 sections and the dentate gyrus of the hippocampus were reduced in the golli-KO mice as well as the density of dendrites in the somatosensory cortex. Furthermore, the golli-KO mice display abnormal behavior including deficits in episodic memory and reduced anxiety. Because of the expression of the golli proteins within neurons in learning and memory centers of the brain, this work has profound implication in neurodegenerative diseases and neurological disorders.

  19. Test setup for accelerated test of high power IGBT modules with online monitoring of Vce and Vf voltage during converter operation

    DEFF Research Database (Denmark)

    de Vega, Angel Ruiz; Ghimire, Pramod; Pedersen, Kristian Bonderup;

    2014-01-01

    of the device in real application. The hypothesis is that ageing of power modules closer to real environment including cooling system, full dc-link voltage and continuous PWM operation could lead to more accurate study of failure mechanism. A new type of test setup is proposed, which can create different real...

  20. Operation Manual of the high voltage generator of the Pelletron electron accelerator; Manual de operacion del generador de alto voltaje del acelerador de electrones Pelletron

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez M, V.; Lopez V, H.; Alba P, U

    1988-04-15

    The first version of a manual to operate the generator of high voltage generator of the Pelletron electron accelerator built in the ININ is presented. Since this generator has several components and/or elements, the one manual present has the purpose that the armed one or maintenance of anyone on its parts, is carried out in an orderly and efficient way. (Author)

  1. DC power flow control for radial offshore multi-terminal HVDC transmission system by considering steady-state DC voltage operation range

    DEFF Research Database (Denmark)

    Irnawan, Roni; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2017-01-01

    of this MTDC system due to the inherited limit from point-to-point (PtP) configuration. An analytic method is proposed in order to estimate the steady-state DC voltage operational points of this MTDC system. The proposed method has been confirmed with a conventional DC power flow study result....

  2. Augmented Reality at the Tactical and Operational Levels of War

    Science.gov (United States)

    2015-10-24

    FINAL 3. DATES COVERED (From - To) 4. TITLE AND SUBTITLE Augmented Reality at the Tactical and Operational Levels of War... Augmented reality technologies have reached a stage where commercially viable systems will soon enter the consumer market. These technologies merge...direct tactical forces. 15. SUBJECT TERMS Augmented Reality , Mediated Reality , Smartphone, HUD, HMD, Information Technology 16. SECURITY

  3. Integrating Multi-Domain Distributed Energy Systems with Electric Vehicle PQ Flexibility: Optimal Design and Operation Scheduling for Sustainable Low-Voltage Distribution Grids

    DEFF Research Database (Denmark)

    Morvaj, Boran; Knezovic, Katarina; Evins, Ralph

    2016-01-01

    for minimising carbon emission in low-voltage distribution grids with high share of distributed energy resources and electric vehicles. The framework determines optimal EV flexibility usage (both active and reactive) while satisfying electric and thermal building demands, and maintaining the distribution grid...... in the stable operation. The model was applied to a real low-voltage Danish distribution grid where measurement data is available on hourly basis in order to determine EV flexibility impacts on carbon emissions, as well as the benefits of optimal DES design. The influence of EV reactive power control...

  4. Voltage-Sharing Converter to Supply Single-Phase Asymmetrical Four-Level Diode-Clamped Inverter With High Power Factor Loads

    DEFF Research Database (Denmark)

    Boora, Arash A.; Nami, Alireza; Zare, Firuz

    2010-01-01

    The output voltage quality of some of the single-phase multilevel inverters can be improved when their dc-link voltages are regulated asymmetrically. Symmetrical and asymmetrical multilevel diode-clamped inverters have the problem of dc-link capacitor voltage balancing, especially when power factor...... of the load is close to unity. In this paper, a new single-inductor multi-output dc/dc converter is proposed that can control the dc-link voltages of a single-phase diode-clamped inverter asymmetrically to achieve voltage quality enhancement. The circuit of the presented converter is explained and the main...... equations are developed. A control strategy is proposed and explained in details. To validate the versatility of the proposed combination of the suggested dc–dc converter and the asymmetrical four-level diode-clamped inverter (ADCI), simulations and experiments have been directed. It is concluded...

  5. Low bias stress and reduced operating voltage in SnCl{sub 2}Pc based n-type organic field-effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Obaidulla, SK. Md., E-mail: obaidulla20@gmail.com; Goswami, D. K., E-mail: xdipak@gmail.com, E-mail: dipak@phy.iitkgp.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India); Giri, P. K., E-mail: giri@iitg.ernet.in [Department of Physics, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India); Centre for Nanotechnology, Indian Institute of Technology Guwahati, Guwahati, Assam 781039 (India)

    2014-05-26

    Vacuum deposited tin (IV) phthalocyanine dichloride (SnCl{sub 2}Pc) field-effect transistors were fabricated on polymethylmethacrylate/aluminum oxide (PMMA/Al{sub 2}O{sub 3}) bilayer gate dielectric, with reduced operating voltage and low contact resistance. The devices with top contact Ag electrodes exhibit excellent n-channel behavior with electron mobility values of 0.01 cm{sup 2}/Vs, low threshold voltages ∼4 V, current on/off ratio ∼10{sup 4} with an operating voltage of 10 V. Bias stress instability effects are investigated during long term operation using thin film devices under vacuum. We find that the amount of bias stress of SnCl{sub 2}Pc based thin film transistor is extremely small with characteristic relaxation time >10{sup 5} s obtained using stretched exponential model. Stressing the SnCl{sub 2}Pc devices by applying 10 V to the gate for half an hour results in a decrease of the source drain current, I{sub DS} of only ∼10% under low vacuum. These devices show highly stable electrical behavior under multiple scans and low threshold voltage instability under electrical dc bias stress (V{sub DS} = V{sub GS} = 10 V, for 2 h) even after 40 days.

  6. The Application of Three-level Voltage Type High Voltage Frequency Conversion Technology in Ocean Engineering Ships%三电平电压型高压变频技术在海洋工程船的应用

    Institute of Scientific and Technical Information of China (English)

    宋艳琼

    2014-01-01

    节能减排、绿色环保,变频电力驱动技术是国内外船舶上应用的发展趋势.特别体现在海洋工程船的大型施工设备和施工设备的驱动系统上.阐述了变频电力驱动技术应用于海洋工程船的优点,介绍了三电平电压型高压变频技术的发展.对三电平电压型高压变频技术进行原理简述,给出了三电平空间电压矢量控制调速系统的主电路拓扑结构,分析了三电平空间电压矢量控制算法的实现,利用MATLAB 7.0/SIMULINK 6.0进行了三电平电压型高压变频调速系统的建模和仿真.%For the purpose of energy saving and emission reduction and green environmental protection , frequency conversion electric drive technology in the world is a development trend applied in ships .Especially this is embodied in large-scale construction equipment of ocean engineering ships and the drive system to construction equipment .This paper elaborates the advantages of variable frequency electric drive technology application in ocean engineering ships , and introduces the development of three-level voltage type high voltage frequency conversion technology.Also, the author illustrates the theories of three-level voltage type high voltage frequency conversion technology , and gives the main circuit topology structure of the three-level space voltage vector control speed regulation system , and analyzes the three-level space voltage vector control algorithm implementation , and finally builds a modeling and simulation of the three-level voltage type high voltage variable frequency speed regulation system by using MATLAB 7.0/SIMULINK 6.0 modules.

  7. 微电网动态电压恢复器运行模式研究%Research on Operation Modes of Dynamic Voltage Restorer in Microgrid

    Institute of Scientific and Technical Information of China (English)

    成瑞芬; 韩肖清; 王鹏; 秦文萍; 张东霞

    2013-01-01

    针对微电网中存在的电压质量问题,提出了基于光蓄发电单元的动态电压恢复器(dynamic voltage restorer,DVR).DVR以光蓄发电单元为储能单元,通过整流器串联接入到低压配电网与微电网公共连接处.提出了DVR的动态电压恢复方式、不间断供电方式和微电源方式的3种运行模式.通过对系统开关信号进行合理控制,实现3种模式的有效切换,提高DVR设备的利用率.DVR的动态电压恢复方式可有效抑制电压暂降或骤升,改善微电网电压质量;不间断供电方式可提高对负荷的供电可靠性;微电源方式可以减少主网的电能供给,实现节能减排.算例结果验证了DVR的有效性.%In allusion to dissatisfied voltage quality of microgrid,a dynamic voltage restorer (DVR) based on photovoltaic (PV) generation/battery units is proposed.Utilizing PV generation/battery units as energy storage component and via rectifier,the proposed DVR is connected in series with the point of common coupling (PCC),where the microgrid low-voltage is connected to distribution network.Three operating modes of DVR,namely the dynamic voltage restoration mode,the uninterruptible power supply mode and the micro-source mode,are put forward.Through reasonably control strategy,the switching-over among the three operation modes can be effectively implemented to improve the utilization rate of DVR.The dynamic voltage restoration mode of DVR can suppress voltage sag and voltage swell effectively,thus the voltage quality is improved; the uninterruptible power supply mode can improve the reliability of power supply; using the micro-source mode,the power supply from power grid can be reduced and it is favorable for energy conservation and emission reduction.The effectiveness of the proposed DVR is verified by results of simulation based on Matlab/Simulink.

  8. 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.

  9. Design of secure operating systems with high security levels

    Institute of Scientific and Technical Information of China (English)

    QING SiHan; SHEN ChangXiang

    2007-01-01

    Numerous Internet security incidents have shown that support from secure operating systems is paramount to fighting threats posed by modern computing environments. Based on the requirements of the relevant national and international standards and criteria, in combination with our experience in the design and development of the ANSHENG v4.0 secure operating system with high security level (hereafter simply referred to as ANSHENG OS), this paper addresses the following key issues in the design of secure operating systems with high security levels: security architecture, security policy models, and covert channel analysis. The design principles of security architecture and three basic security models: confidentiality,integrity, and privilege control models are discussed, respectively. Three novel security models and new security architecture are proposed. The prominent features of these proposals, as well as their applications to the ANSHENG OS, are elaborated.Cover channel analysis (CCA) is a well-known hard problem in the design of secure operating systems with high security levels since to date it lacks a sound theoretical basis and systematic analysis approach. In order to resolve the fundamental difficulties of CCA, we have set up a sound theoretical basis for completeness of covert channel identification and have proposed a unified framework for covert channel identification and an efficient backward tracking search method. The successful application of our new proposals to the ANSHENG OS has shown that it can help ease and speedup the entire CCA process.

  10. Analysis of capacitive effect and life estimation of hydrodynamic journal bearings on repeated starts and stops of a machine operating under the influence of shaft voltages

    Science.gov (United States)

    Prashad, Har; Rao, K. N.

    1994-07-01

    A theoretical analysis has been carried out to study the capacitive effect and life estimation of hydrodynamic journal bearings on repeated starts and stops of a machine operating under the influence of shaft voltages. The analysis gives the time required for the charge accumulation and increase of charge with time on the liner surface of a journal bearing based on bearing capacitance, resistance of film thickness, and the shaft voltage. Also, it investigates the effect of gradual leakage of the accumulated charges with time as the shaft voltage falls when the power supply to the machine is switched off. This paper gives an approach to determine the ratio of the number of shaft revolutions required for charge accumulation and gradual discharge of the accumulated charges on the liner surface of a bearing depending on bearing-to-shaft voltage. Also, the number of repeated starts and stops before initiation of craters on the liner surface of a hydrodynamic journal bearing is established to restrict deterioration and damage of the liner. The diagnosis has the potential to study the transient effect of the shaft voltages on a journal bearing during the start and stop cycle of a machine.

  11. Integrated Differential Three-Level High-Voltage Pulser Output Stage for CMUTs

    DEFF Research Database (Denmark)

    Llimos Muntal, Pere; Larsen, Dennis Øland; Jørgensen, Ivan Harald Holger;

    2015-01-01

    A new integrated differential three-level highvoltage pulser output stage to drive capacitive micromachined ultrasonic transducers (CMUTs) is proposed in this paper. A topology comparison between the new differential output stage and the most commonly used single-ended topology is performed...

  12. Amorphous Strontium Titanate Film as Gate Dielectric for Higher Performance and Low Voltage Operation of Transparent and Flexible Organic Field Effect Transistor.

    Science.gov (United States)

    Yadav, Sarita; Ghosh, Subhasis

    2016-04-27

    We report that the pervoskite material, strontium titanate (STO) can be used as a gate dielectric layer of flexible and low voltage organic field effect transistor (OFET). The crystallinity, dielectric constant, and surface morphology of STO films can be controlled by the engineering of the growth condition. Under optimized growth condition, amorphous films of STO show a much better gate dielectric compared to other gate dielectrics used to date, with very small leakage current density for flexible and low voltage (transistors with amorphous STO gate dielectric show high mobility of 2 cm(2)/(V s), on/off ratio of 10(6), subthreshold swing of 0.3 V/dec and low interface trap density. Similarly excellent performance has been obtained in copper phthalocyanine (CuPc) based OFETs with on/off ratio ∼10(5) and carrier mobility ∼5.9 × 10(-2) cm(2)/(V s). Moreover, the operating voltage (∼5 V) has been reduced by more than one order of magnitude. It has been demonstrated that the low processing temperature of amorphous STO makes it the most suitable gate dielectric for flexible and transparent organic devices to operate under low voltage.

  13. DEVELOPMENTAL LEVEL OF THINKING OPERATIONS AT CHILDREN WITH SPEECH IMPAIRMENTS

    Directory of Open Access Journals (Sweden)

    Silvana FILIPOVA

    2008-12-01

    Full Text Available Simple accumulation of perceptive data, motor actions, verbal descriptions and intelligence that manages previously mentioned is not due to cognitive processes. “In order to get familiar with the objects, the subject has to act on them, which means transform them. Starting from the elementary sensory-motor actions, until the finest intellectual operations (formal-logic, which are actions yet, but interiorized and exe­cuted in the thoughts, cognition is continuously related to actions and operations, e.g. trans­formations (1.J. Piageot identifies three major levels of intellectual operation development:1. Sensory-motor intelligence – from birth up to the age of 18 months or until the end of the second year of age.2. Representational intelligence level – leading to specific operations. This is a longer deve­lop­men­tal period which lasts from the end of se­cond year up to 11-12 years of age.

  14. Optimal operation control of low-voltage grids with a high share of distributed power generation[Dissertation 17063]; Optimierte Betriebsfuehrung von Niederspannungsnetzen mit einem hohen Anteil an dezentraler Erzeugung

    Energy Technology Data Exchange (ETDEWEB)

    Malte, C. T.

    2007-07-01

    targets during development were that the system is able to manage autonomously a selected low-voltage grid including the installed (controllable) grid devices in order to improve power quality as well as to guarantee an economically optimised operation of the grid. Therefore, this system simplifies the integration of more and more DG units into already existing distribution grids and generates at the same time an economical and technical benefit for the concerned grid operator. All essential algorithms for the operation of PoMS have been developed within this PhD thesis. The approaches used in this work have been designed specially to fit for the application in limited low-voltage grid segments, e.g. area grids or industrial grids. It is a big advantage that the algorithms have been designed in such a general and scalable way, so that they can be used in a slightly modified form also for the optimisation of larger grids. From the very beginning the aim of the project was not only to design the system theoretically but also to test it under real conditions in an existing low-voltage grid. For that a fix time slot was given that had to be met under all circumstances. Therefore, the big challenge in the framework of this PhD thesis was not only to develop appropriate algorithms, but also to do this in the given time. With the successful test of PoMS it could be demonstrated that the developed algorithms are practical and allow an economically optimised grid management under real conditions. Further, it could be shown that PoMS can be used even for the operation of permanently islanded grids as well as for the operation of temporary islanded grids due to faults or interruptions on higher voltage levels ('Fault Ride Through'). (author)

  15. A Dynamic Consensus Algorithm based Low-Voltage Ride-Through Operation of Power Converters in Grid-Interactive Microgrids

    DEFF Research Database (Denmark)

    Zhao, Xin; Meng, Lexuan; Savaghebi, Mehdi

    2016-01-01

    of the converters cannot be equally shared if no extra current balancing loop is added. Accordingly, a dynamic consensus algorithm (DCA) based negative/positive sequence current sharing scheme is proposed in this paper. Finally, a lab-scale AC microgrid was designed and tested in the lab to validate the feasibility...... control based voltage support strategy has been proposed to aid MGs riding through three phase asymmetrical voltage sags. However, since the line impedance from each converter to the point of common coupling (PCC) is not identical, both positive sequence and negative sequence output current...

  16. Stable single-mode operation of injection-seeded Q-switched Nd:YAG laser by sine voltage modulation

    Institute of Scientific and Technical Information of China (English)

    Yongfei Gao; Junxuan Zhang; Huaguo Zang; Xiaolei Zhu; Yingjie Yu; Weibiao Chen

    2016-01-01

    Based on the modified ramp and fire technique,a novel injection seeding approach with real-time resonance tracking is successfully demonstrated in a single-frequency Nd:YAG pulsed laser.Appling a high-frequency sinusoidal modulation voltage to one piezo actuator and an adjustable DC voltage to another piezo actuator for active feedback,single-mode laser output with high-frequency stability is obtained,and the effect of the piezo hysteresis on the frequency stability can be eliminated for a laser diode pumped Q-switched Nd:YAG laser at a repetition rate of 400 Hz.

  17. WRAP low level waste (LLW) glovebox operational test report

    Energy Technology Data Exchange (ETDEWEB)

    Kersten, J.K.

    1998-02-19

    The Low Level Waste (LLW) Process Gloveboxes are designed to: receive a 55 gallon drum in an 85 gallon overpack in the Entry glovebox (GBIOI); and open and sort the waste from the 55 gallon drum, place the waste back into drum and relid in the Sorting glovebox (GB 102). In addition, waste which requires further examination is transferred to the LLW RWM Glovebox via the Drath and Schraeder Bagiess Transfer Port (DO-07-201) or sent to the Sample Transfer Port (STC); crush the drum in the Supercompactor glovebox (GB 104); place the resulting puck (along with other pucks) into another 85 gallon overpack in the Exit glovebox (GB 105). The status of the waste items is tracked by the Data Management System (DMS) via the Plant Control System (PCS) barcode interface. As an item is moved from the entry glovebox to the exit glovebox, the Operator will track an items location using a barcode reader and enter any required data on the DMS console. The Operational Test Procedure (OTP) will perform evolution`s (described below) using the Plant Operating Procedures (POP) in order to verify that they are sufficient and accurate for controlled glovebox operation.

  18. Loss and thermal redistributed modulation methods for three-level neutral-point-clamped wind power inverter undergoing Low Voltage Ride Through

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede

    2012-01-01

    investigates the loss and thermal performances of a 10 MW 3L-NPC wind power inverter undergoing Low Voltage Ride Through (LVRT) operation. A series of new space vector modulation methods are then proposed to relocate the thermal loading among the power switching devices. It is concluded that, with the proposed...

  19. Achieving high mobility, low-voltage operating organic field-effect transistor nonvolatile memory by an ultraviolet-ozone treating ferroelectric terpolymer

    Science.gov (United States)

    Xiang, Lanyi; Wang, Wei; Xie, Wenfa

    2016-11-01

    Poly(vinylidene fluoride–trifluoroethylene) has been widely used as a dielectric of the ferroelectric organic field-effect transistor (FE-OFET) nonvolatile memory (NVM). Some critical issues, including low mobility and high operation voltage, existed in these FE-OFET NVMs, should be resolved before considering to their commercial application. In this paper, we demonstrated low-voltage operating FE-OFET NVMs based on a ferroelectric terpolymer poly(vinylidene-fluoride-trifluoroethylene-chlorotrifluoroethylene) [P(VDF-TrFE-CTFE)] owed to its low coercive field. By applying an ultraviolet-ozone (UVO) treatment to modify the surface of P(VDF-TrFE-CTFE) films, the growth model of the pentacene film was changed, which improved the pentacene grain size and the interface morphology of the pentacene/P(VDF-TrFE-CTFE). Thus, the mobility of the FE-OFET was significantly improved. As a result, a high performance FE-OFET NVM, with a high mobility of 0.8 cm2 V‑1 s‑1, large memory window of 15.4~19.2, good memory on/off ratio of 103, the reliable memory endurance over 100 cycles and stable memory retention ability, was achieved at a low operation voltage of ±15 V.

  20. 低整流电压应力的推挽正激三电平变换器%Push-Pull Forward Three-Level Converter with Reduced Rectifier Voltage Stress

    Institute of Scientific and Technical Information of China (English)

    姚志垒; 肖岚; 黄勇; 丁连锋

    2012-01-01

    This paper presents a push-pull forward (PPF) three-level (TL) converter, which is suitable for low and wide-range input voltage applications, such as renewable energy resources. Half of the switches sustain half of the input voltage, and the others sustain one and one-half input voltage. However, voltage stress of the rectifier diode is high with the conventional TL control strategy, especially in high output-voltage condition, considering voltage spike across the rectifier diode caused by leakage inductance. When 1/2 level of the secondary rectified voltage shows first and 1 level of that appears later, the voltage stress across the rectifier diode can be reduced by paralleling with external capacitor. The operating principle and selection of the external capacitor are analyzed. Finally, experimental results of a 500 W PPF TL converter verify the theoretical analysis.%提出了一种推挽正激三电平变换器。它适合于低压宽输入的场合,如可再生能源。该变换器的一半开关管承受1/2的输入电压,另一半承受3/2的输入电压。采用传统的三电平控制策略,并考虑变压器漏感在整流二极管上产生的电压尖峰,整流二极管的电压应力高,尤其是在高输出电压的场合。为了解决上述问题,采用二次整流电压波形先出现1/2电平,后出现1电平的控制策略,并通过在整流二极管上并联电容的方法,降低了整流二极管的电压应力。该文详细分析了该变换器的工作原理,讨论了整流二极管并联电容的选取。最后,以一台500W的原理样机对理论分析并进行了实验验证。

  1. Wholesale Electricity Market Design with Increasing Levels of Renewable Generation: Incentivizing Flexibility in System Operations

    Energy Technology Data Exchange (ETDEWEB)

    Ela, Erik; Milligan, Michael; Bloom, Aaron; Botterud, Audun; Townsend, Aaron; Levin, Todd; Frew, Bethany A.

    2016-05-01

    This paper discusses the importance and challenges of incentivizing flexibility during short-term operations of the bulk power system due to the increasing variability and uncertainty from growing penetrations of variable generation (VG). Operational flexibility can refer to many aspects of a resource's capability to support the power system, such as the speed, range, and duration of power output, as well as the ability to autonomously respond to frequency or voltage changes. Inefficient utilization of existing flexibility, or unwillingness of resources to provide flexibility, can compromise system reliability by not meeting the changing net load, and it can also lead to higher costs when an inefficient use of flexibility resources occurs. There are many existing characteristics of market design that incentivize flexibility in some manner. How they incentivize the provision of flexibility as well as the level of flexibility is still debated. We explore some of these existing market designs, as well as new market mechanisms, such as pay-for-performance regulating reserve and flexible ramping products, that aim to explicitly incentivize the provision of more flexibility to the system, particularly as a result of increasing VG penetration levels.

  2. Realization and Operation of Automatic Voltage Control in Dongguan Power Grid%东莞电网自动电压控制的实现与运行

    Institute of Scientific and Technical Information of China (English)

    言宇; 冯林桥

    2015-01-01

    Taking Dongguan power grid for example, this paper introduced the necessity to construct an automatic voltage control (AVC) system and expounded the implement method, control strategy and safety precautions of AVC. After the closed loop was put into operation, the voltage eligibility rate was improved and the power grid loss was reduced, which verifies the effectiveness of AVC function, to make the reactive voltage management of power grid realize safe, stable, high-quality and economic operation.%以东莞电网为例,介绍了建设自动电压控制(AVC)系统的必要性,并阐述了AVC系统实现的方法、控制策略及安全保障措施。经闭环投运,提高了电压合格率,降低了网损,验证了AVC功能的有效性,使电网无功电压管理真正实现了安全、稳定、优质、经济运行。

  3. Operation and thermal loading of three-level Neutral-Point-Clamped wind power converter under various grid faults

    DEFF Research Database (Denmark)

    Ma, Ke; Blaabjerg, Frede; Liserre, Marco

    2012-01-01

    In order to fulfill the continuous growing grid-side demands, the full-scale power converters are becoming more and more popular in the wind power application. Nevertheless, the more severe loading of the power semiconductor devices in the full-scale power converters, especially during Low Voltag...... devices is highlighted. It has been found that the thermal loading of the phases of the power converter may be uneven and dependent on the different types and severities of grid voltage dips as well as on the chosen control algorithms....... Ride Through (LVRT) operation under grid faults, may compromise the reliability of the system and consequently further increase its cost. In this paper, the impact of various grid faults on a three-level Neutral-Point-Clamped (3L-NPC) grid-converter in terms of thermal loading of power semiconductor...

  4. 超宽工作电压DC/DC变换器设计%Design of wide operating voltage DC/DC converter

    Institute of Scientific and Technical Information of China (English)

    王大为; 赵瑞杰; 陶学军; 田素立; 李朝锋

    2012-01-01

    Based on the situation of the wide output voltage range of solar photovoltaic power generation systems, a wide operating voltage of the DC / DC converter was designed. To solve the shortcoming of high voltage stress of the power when the switch was off, the voltage regulator tube was Introduced in order to clamp the voltage. To ensure the saturation switch conduction of the MOSFET, a rational circuit was designed to induce the current from the secondary circuit as the MOSFET gate driver. Based on the theoretical analysis, simulation and optimization, a 15 W, 1 000 V /200 V input prototype was designed.The test results show that the converter can work stably tor a long time.%针对太阳能光伏发电系统输出电压较宽的情况,设计了一种超宽工作电压的DC/DC变换器.利用稳压管在开关关断时对电路进行电压钳位,解决了单管反激变换器在高电压输入时电力MOSFET电压应力过高的缺陷.通过合理设计电路并从电路副边引入电流作为MOSFET栅极驱动,可以保证开关管的饱和导通.在理论分析、仿真优化、反复调试的基础上,设计了一款15W、1 000 V/200 V输入的样机.经过测试,此变换器可以长时间稳定工作且转换效率比较高.

  5. Operation of High-Voltage Transverse Shock Wave Ferromagnetic Generator in the Open Circuit and Charging Modes

    Science.gov (United States)

    2005-06-01

    FMGs are based on the transverse (when the shock wave propagates across the magnetization vector M) shock demagnetization of Nd2Fe14B hard...generators based on the transverse (when the shock wave propagates across the magnetization vector M) shock wave demagnetization of Nd2Fe14B hard...and photo of a high-voltage transverse FMG are shown in Fig. 1. It contains a hollow hard ferromagnetic cylindrical Nd2Fe14B energy-carrying

  6. The effect of the variable frequency drive of the CNC roll grinding machine on the operation of other devices in low-voltage electrical installation

    Directory of Open Access Journals (Sweden)

    Simić Ninoslav

    2016-01-01

    Full Text Available This paper presents one of the observations that have been collected during the years of testing of electrical installations. A typical case from industrial plant in which are installed loads with variable frequency regulation is analyzed. We propose a simple way by measuring the frequency of the voltage in the objects, to establish the existence of possible irregularities in the operation of the individual units and analyze the influence of the current and voltage signal shape of one load to the work of other loads in the plant. The need for verification of electrical installations immediately upon receipt and installation of electrical equipment is emphasized and the use of the latest standards in the design and selection of equipment, in order to avoid unplanned expenses is recommended.

  7. First operation and drift field performance of a large area double phase LAr Electron Multiplier Time Projection Chamber with an immersed Greinacher high-voltage multiplier

    CERN Document Server

    Badertscher, A; Degunda, U; Epprecht, L; Gendotti, A; Horikawa, S; Knecht, L; Lussi, D; Marchionni, A; Natterer, G; Nguyen, K; Resnati, F; Rubbia, A; Viant, T

    2012-01-01

    We have operated a liquid-argon large-electron-multiplier time-projection chamber (LAr LEM-TPC) with a large active area of 76 $\\times$ 40 cm$^2$ and a drift length of 60 cm. This setup represents the largest chamber ever achieved with this novel detector concept. The chamber is equipped with an immersed built-in cryogenic Greinacher multi-stage high-voltage (HV) multiplier, which, when subjected to an external AC HV of $\\sim$1 kV$_{\\mathrm{pp}}$, statically charges up to a voltage a factor of $\\sim$30 higher inside the LAr vessel, creating a uniform drift field of $\\sim$0.5 kV/cm over the full drift length. This large LAr LEM-TPC was brought into successful operation in the double-phase (liquid-vapor) operation mode and tested during a period of $\\sim$1 month, recording impressive three-dimensional images of very high-quality from cosmic particles traversing or interacting in the sensitive volume. The double phase readout and HV systems achieved stable operation in cryogenic conditions demonstrating their go...

  8. Operation of the Upgraded ATLAS Level-1 Central Trigger System

    CERN Document Server

    Glatzer, Julian Maximilian Volker; The ATLAS collaboration

    2015-01-01

    The ATLAS Level-1 Central Trigger (L1CT) system is a central part of ATLAS data-taking and has undergone a major upgrade for Run 2 of the LHC, in order to cope with the expected increase of instantaneous luminosity of a factor of 2 with respect to Run 1. The upgraded hardware offers more flexibility in the trigger decisions due to the double amount of trigger inputs and usable trigger channels. It also provides an interface to the new topological trigger system. Operationally - particularly useful for commissioning, calibration and test runs - it allows concurrent running of up to 3 different sub-detector combinations. In this contribution, we give an overview of the operational software framework of the L1CT system with particular emphasis of the configuration, controls and monitoring aspects. The software framework allows a consistent configuration with respect to the ATLAS experiment and the LHC machine, upstream and downstream trigger processors, and the data acquisition. Trigger and dead-time rates are m...

  9. Operation of the Upgraded ATLAS Level-1 Central Trigger System

    CERN Document Server

    Glatzer, Julian Maximilian Volker; The ATLAS collaboration

    2015-01-01

    The ATLAS Level-1 Central Trigger (L1CT) system is a central part of ATLAS data-taking and has undergone a major upgrade for Run 2 of the LHC, in order to cope with the expected increase of instantaneous luminosity of a factor of 2 with respect to Run 1. The upgraded hardware offers more flexibility in the trigger decisions due to the double amount of trigger inputs and usable trigger channels. It also provides an interface to the new topological trigger system. Operationally - particularly useful for commissioning, calibration and test runs - it allows concurrent running of up to 3 different subdetector combinations. An overview of the operational software framework of the L1CT system with particular emphasis of the configuration, controls and monitoring aspects is given. The software framework allows a consistent configuration with respect to the ATLAS experiment and the LHC machine, upstream and downstream trigger processors, and the data acquisition. Trigger and dead-time rates are monitored coherently at...

  10. High Level Control Applications for SOLEIL Commissioning and Operation

    CERN Document Server

    Nadolski, Laurent S; Ho, Katy; Leclercq, Nicolas; Ounsy, Majid; Petit, Sylvain

    2005-01-01

    The SOLEIL control system, namely TANGO developed in collaboration with ESRF, is now mature and stable. TANGO has also been chosen now by several other laboratories. High-level control applications implemented in the control room for the storage ring, the two transfer lines, and the booster will be described in this paper. Three kinds of tools for commissioning are used. First the generic TANGO tools (alarms, simple graphical control applications), which allow us to control in a simple way any TANGO Device Server. Secondly a Matlab Middle Layer (adapted from ALS and SPEAR3): Matlab is fully interconnected with TANGO; it is used primarily for writing Physics control applications. Finally Globalscreen, a commercial SCADA software devoted for building operation applications has been selected (panels for controlling or displaying setpoint, readback values, status of equipments). In addition an overview of the historical and short-term databases for the accelerators will be given. They have been developed in house...

  11. 一种考虑风电随机性的电力系统电压运行区间计算方法%Voltage operating range calculation method for electric power system considering wind power randomness

    Institute of Scientific and Technical Information of China (English)

    李苗; 邓长虹; 游佳斌; 周沁

    2016-01-01

    针对风电场出力的波动性使风电接入地区电网的随机性增强,并网点电压波动的频率和幅度变大,造成的电压稳定问题,以实际风电场的运行数据为基础,通过统计学方法分析风电场输出功率的波动特性,得到风功率波动率在不同时间尺度内的分布参数以及95%置信区间,并分析不同风电水平下的电压波动特性,在此基础上提出使用t location⁃scale分布函数对电压波动率的概率分布进行拟合,进而得出一种基于风功率波动特性以及仿射区间潮流算法的电压运行区间计算方法,通过该方法计算得到的电压运行区间反映了在风功率波动条件下未来一段时间内电力系统电压的运行区间,对风电接入系统的运行、控制及规划工作具有重要的指导意义。%The fluctuation of wind power plant can enhance the power grid randomness of wind power access region,and in⁃crease the frequency and amplitude of the voltage fluctuation at the connection point,which may cause the voltage stability problem. On the basis of the operating data of practical wind power plant,the statistical method is used to analyze the fluctuation charac⁃teristic of the wind power plant output power,so as to obtain the distribution parameters and 95% confidence interval of wind power fluctuation in different time scales,and analyze the voltage fluctuation characteristic under different wind power levels. On this basis,the t location⁃scale distribution function is used to fit the probability distribution of voltage fluctuation rate,and the voltage operating range calculation method based on wind power fluctuation characteristic and affine interval power flow algo⁃rithm is obtained. The voltage operating range calculated by this method reflects the possible operating voltage range of the electric power system within a period of time in the future under the condition of wind power fluctuation,and has an

  12. Quantitative analysis of irreversibilities causes voltage drop in fuel cell (simulation and modeling)

    Energy Technology Data Exchange (ETDEWEB)

    Ghadamian, Hossein [Azad Univ., Dept. of Energy Engineering, Tehran (Iran); Saboohi, Yadolah [Sharif Energy Research Inst. (SERI), Tehran (Iran)

    2004-11-30

    Power level of a fuel cell depends on its operating condition, which is product of voltage and current-density the highest level of voltage is identified as reversible open circuit voltage (ROCV), which represents an ideal theoretical case [J. Larmin, A. Dicks, Fuel Cell System Explained, Wiley, 2000 (ISBN)]. Compared to that is ideal operating voltage which is usually characterized as open circuit voltage (OCV). An evaluation of deviation of operating voltage level from ideal operational case may provide information on the extent of improving efficiency and energy efficiency of a fuel cell. Therefore, quantification of operation deviation from OCV is the main point that is discussed in the present paper. The analysis procedure of voltage drop is based on step-by-step review of voltage drops over activation, internal currents (fuel-cross-over), Ohmic and mass-transport or concentration losses. Accumulated total voltage drops would be estimated as a sum of aforementioned losses. The accumulated voltage drops will then be reduced from OCV to obtain the operating voltage level. The above numerical analysis has been applied to identify the extents of voltage drop. The possible reducing variables in voltage drops reviewed and concluded that the activation loss has considerable impact on total voltage drops and it explains the most part of total losses. It is also found that the following correspondence parameters cause decrease in voltage drops: 1. Temperature increasing; 2. Pressure increasing; 3. Hydrogen or oxygen concentration increasing; 4. Electrode effective surface increasing; 5. Electrode and electrolyte, conductivity modification; 6. Electrolyte thickness reducing up to possible limitation; 7. Connection modification. (Author)

  13. The low threshold voltage n-type silicon transistors based on a polymer/silica nanocomposite gate dielectric: The effect of annealing temperatures on their operation

    Science.gov (United States)

    Hashemi, Adeleh; Bahari, Ali; Ghasemi, Shahram

    2017-09-01

    In this work, povidone/silica nanocomposite dielectric layers were deposited on the n-type Si (100) substrates for application in n-type silicon field-effect transistors (FET). Thermogravimetric analysis (TGA) indicated that strong chemical interactions between polymer and silica nanoparticles were created. In order to examine the effect of annealing temperatures on chemical interactions and nanostructure properties, annealing process was done at 423-513 K. Atomic force microscopy (AFM) images show the very smooth surfaces with very low surface roughness (0.038-0.088 nm). The Si2p and C1s core level photoemission spectra were deconvoluted to the chemical environments of Si and C atoms respectively. The obtained results of deconvoluted X-ray photoelectron spectroscopy (XPS) spectra revealed a high percentage of silanol hydrogen bonds in the sample which was not annealed. These bonds were inversed to stronger covalence bonds (siloxan bonds) at annealing temperature of 423 K. By further addition of temperature, siloxan bonds were shifted to lower binding energy of about 1 eV and their intensity were abated at annealing temperature of 513 K. The electrical characteristics were extracted from current-Voltage (I-V) and capacitance-voltage (C-V) measurements in metal-insulator-semiconductor (MIS) structure. The all n-type Si transistors showed very low threshold voltages (-0.24 to 1 V). The formation of the strongest cross-linking at nanostructure of dielectric film annealed at 423 K caused resulted in an un-trapped path for the transport of charge carriers yielding the lowest threshold voltage (0.08 V) and the highest electron mobility (45.01 cm2/V s) for its FET. By increasing the annealing temperature (473 and 513 K) on the nanocomposite dielectric films, the values of the average surface roughness, the capacitance and the FET threshold voltage increased and the value of FET electron field-effect mobility decreased.

  14. 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.

  15. Comparison of three-phase three-level voltage source inverter with intermediate dc–dc boost converter and quasi-Z-source inverter

    DEFF Research Database (Denmark)

    Panfilov, Dmitry; Husev, Oleksandr; Blaabjerg, Frede

    2016-01-01

    This study compares a three-phase three-level voltage source inverter with an intermediate dc-dc boost converter and a quasi-Z-source inverter in terms of passive elements values and dimensions, semiconductor stresses, and overall efficiency. A comparative analysis was conducted with relative par...

  16. Operational experience with the new LEIR digital low-level RF System

    CERN Document Server

    Angoletta, ME

    2010-01-01

    The LEIR Low-Level (LLRF) system is the first all-digital low LLRF system that has been put into operation in a CERN circular machine. It is a very compact system, composed of one VME64x crate and of few NIM modules. System capabilities include typical beam control tasks, such as frequency program, beam phase, radial and extraction synchronization feedback loops, as well as cavity voltage/phase feedback loops. The system is also capable of coping with the large variation of the revolution frequency during an acceleration cycle as well as with the high dynamic range required by the LEIR cavities operation. Extensive diagnostics and observation capabilities are built-in and the system’s control parameters are fully configurable remotely and in-between cycles. Over the various LEIR runs, the LLRF system has proven to be reliable and reproducible as well as extremely flexible and powerful. These characteristics are essential for a LLRF system and LEIR is already profiting from them. Moreover, high beam availabi...

  17. On-chip frequency compensation with a dual signal path operational transconductance amplifier for a voltage mode control DC/DC converter

    Science.gov (United States)

    Qiang, Ye; Jie, Liu; Bing, Yuan; Xinquan, Lai; Ning, Liu

    2012-04-01

    A novel on-chip frequency compensation circuit for a voltage-mode control DC/DC converter is presented. By employing an RC network in the two signal paths of an operational transconductance amplifier (OTA), the proposed circuit generates two zeros to realize high closed-loop stability. Meanwhile, full on-chip integration is also achieved due to its simple structure. Hence, the number of off-chip components and the board space is greatly reduced. The structure of the dual signal path OTA is also optimized to help get a better transition response. Implemented in a 0.5 μm CMOS process, the voltage mode control DC/DC converter with the proposed frequency compensation circuit exhibits good stability. The test results show that both load and line regulations are less than 0.3%, and the output voltage can be recovered within 15 μs for a 400 mA load step. Moreover, the compensation components area is less than 2% of the die's area and the board space is also reduced by 11%. The efficiency of the whole chip can be up to 95%.

  18. Low-operating-voltage polymer thin-film transistors based on poly(3-hexylthiophene) with hafnium oxide as the gate dielectric

    OpenAIRE

    Liu, YR; Deng, LF; Yao, RH; Lai, PT

    2010-01-01

    The effects of hafnium oxide $(hbox{HfO}-{2})$ gate dielectric annealing treatment in oxygen $(hbox{O}-{2})$ and ammonia $(hbox{NH}-{3})$ ambient on the electrical performance of polymer thin-film transistors (PTFTs) based on poly(3-hexylthiophene) are investigated. The PTFTs with $hbox{HfO}-{2}$ gate dielectric and also octadecyltrichlorosilane surface modification, prepared by spin-coating process, exhibit good performance, such as a small threshold voltage of $-$0.5 V and an operating volt...

  19. Algorithm of Dynamic Operation Process of Hydraulic Automatically Operated Canals with Constant-Downstream Level Gates

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li-wei; FENG Xiao-bo; WANG Chang-de

    2005-01-01

    On the basis of analysis the governing process of downstream water level gates AVIO and AVIS, a mathematical model for simulation of dynamic operation process of hydraulically automated irrigation canals installed with AVIO and AVIS gates is presented. the main point of this mathematical model is firstly applying a set of unsteady flow equations (St. Venant equations here) and treating the condition of gate movement as its dynamic boundary, and then decoupling this interaction of gate movement with the change of canal flow. In this process, it is necessary to give the gates' open-loop transfer function whose input is water level deviation and output is gate discharge. The result of this simulation for a practical reach has shown it has satisfactory accuracy.

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

    National Research Council Canada - National Science Library

    Kobayashi, Masaharu; Hiramoto, Toshiro

    2016-01-01

    Internet-of-Things (IoT) technologies require a new energy-efficient transistor which operates at ultralow voltage and ultralow power for sensor node devices employing energy-harvesting techniques as power supply...

  1. Power electronic topology and switching-concept for identification of the grid impedance at medium-voltage-level; Leistungselektronisches Schaltungskonzept zur Identifikation der Netzimpedanz auf der Mittelspannungsebene

    Energy Technology Data Exchange (ETDEWEB)

    Do, Thanh Trung; Jordan, Michael; Langkowski, Hauke; Schulz, Detlef [Helmut-Schmidt-Univ., Hamburg (Germany). Professur fuer Elektrische Energiesysteme; Leutwyler, Reto [ABB Switzerland Ltd., Lenzburg (Switzerland). Semiconductors

    2011-07-01

    The grid impedance at a point of common coupling (PCC) is an important parameter for grid integration of Renewable Energies, because it determines the maximum input power capacity of the corresponding PCC. The grid impedance is time and frequency dependent, which makes an analytical or simulative identification challenging. Therefore in practise the data obtained from these calculations are often incorrect and do not reflect the real grid structure. In order to determine the grid impedance more accurately the Helmut-Schmidt-University is developing a novel measurement device to identify the time and frequency dependent grid impedance on the medium-voltage-level up to 20 kVrms. For the application in medium-voltage-grids a special switching concept with high voltage thyristors and innovative presspack-IGBTs has been developed in cooperation with ABB Switzerland Ltd./Semiconductors. This contribution presents the basic grid impedance measurement method and its realization with power electronic components. (orig.)

  2. Integrating Mission Type Orders into Operational Level Intelligence Collection

    Science.gov (United States)

    2011-05-27

    Operational Control OPLAN Operation Plan OSINT Open Source Intelligence OT Exercise OLYMPIC TITAN PED Processing, Exploitation, and Dissemination PIR...human intelligence (HUMINT), open source intelligence ( OSINT ), and counterintelligence (CI). These are human-oriented collection capabilities and

  3. Current regulators for I/SUP 2/L circuits to be operated from low-voltage power supplies

    DEFF Research Database (Denmark)

    Bruun, Erik; Hansen, Ole

    1980-01-01

    A new bandgap current reference is described which can be used to control the injector current of I/SUP 2/L circuits for supply voltages down to about 1 V. For small currents the total injector current is obtained as a mirror of the reference current. For large injector currents the current control...... is performed by a series regulator which compares the injector current of one I/SUP 2/L gate to the reference current. The described reference current can be adjusted to give a variation with temperature of about 60 ppm/°C over the temperature range -10 to +70°C. However, in some applications a nonzero......, but well controlled temperature coefficient is desired. It is shown how a temperature stable ring oscillator with I/SUP 2/L gates can be constructed by tailoring the temperature dependence of the supply current appropriately....

  4. 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

  5. System-level challenges in pressure-operated soft robotics

    Science.gov (United States)

    Onal, Cagdas D.

    2016-05-01

    Last decade witnessed the revival of fluidic soft actuation. As pressure-operated soft robotics becomes more popular with promising recent results, system integration remains an outstanding challenge. Inspired greatly by biology, we envision future robotic systems to embrace mechanical compliance with bodies composed of soft and hard components as well as electronic and sensing sub-systems, such that robot maintenance starts to resemble surgery. In this vision, portable energy sources and driving infrastructure plays a key role to offer autonomous many-DoF soft actuation. On the other hand, while offering many advantages in safety and adaptability to interact with unstructured environments, objects, and human bodies, mechanical compliance also violates many inherent assumptions in traditional rigid-body robotics. Thus, a complete soft robotic system requires new approaches to utilize proprioception that provides rich sensory information while remaining flexible, and motion control under significant time delay. This paper discusses our proposed solutions for each of these system-level challenges in soft robotics research.

  6. 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.

  7. Assessment of duration of the drive operation in the mode of kinetic energy recovery under power supply voltage sags in electrical grids of mechanical engineering enterprises

    Science.gov (United States)

    Shonin, O. B.; Novozhilov, N. G.

    2017-02-01

    Voltage sags in electric grids of mechanical engineering enterprises may lead to disconnection of important power consumers with variable frequency drives from the power grid and further interruption of the production process. The paper considers a sensorless V/f control system of еру induction motor drive under normal conditions and under voltage sags on the basis of a computer model of the drive and derivation of a formula for assessment of possible duration of the drive operation in the mode of controlled recovery of kinetic energy accumulated in rotating mass of the drive. Results of simulations have been used to validate results of calculations of the rotor velocity deceleration made in a closed form obtained from the equation reflecting the balance of torques. It is shown that results of calculations practically coincide with results of simulations in the range up to 5% of the velocity initial value. The proposed formula may be useful for estimation of the duration of the drive operation in the mode of recovery of kinetic energy depending on parameters of the motor and driven mechanisms.

  8. Comparative Analysis of Different PWM Techniques to Reduce the Common Mode Voltage in Three-Level Neutral-Point-Clamped Inverters for Variable Speed Induction Drives

    Directory of Open Access Journals (Sweden)

    Bharati Raja

    2012-12-01

    Full Text Available This work presents the comparative study of the different PWM techniques to reduce the common-mode voltage (CMV at the output of neutral point diode clamped inverter for variable speed drives. Here the comparative study is done by the phase opposition disposed (POD, sinusoidal pulse width modulation (SPWM, phase disposition (PD, phase shift (PS space vector modulation (SVM techniques are proposed. A good trade-off between the quality of the output voltage and the partial magnitude of the CMV is achieved in this work. The scheme is proposed for three-level inverter. This work realizes the implementation of Three-level diode clamped MLI for three-phase (Y-Δ induction motor with the implementation of a space vector modulation technique without any additional control algorithm to reduce CMV within the range + Vdc/6. The Simulation with a 1HP induction motor drive system is setup in Matlab-2011b  and the same results validated effectively by hardware – FPGA-SPARTEN III processor and its shows that the CM voltage is effectively reduced and the maximum output voltage is not affected.  

  9. Analysis of the modal and operational indicators of 110 to 750 kilovolt voltage substations of a power system

    Energy Technology Data Exchange (ETDEWEB)

    Ovseychuk, V.A.; Shesteren, V.Ye.

    1983-01-01

    Studies are conducted using statistical and mathematical methods of the schedules of electrical loads and correlated modal and operational indicators of regional 100 to 750 kilovolt substations (PS) of the country's electric power system (EES). An analysis is conducted of the graphs and correlated modal and operational indicators of step down regional 110 to 750 kilovolt substations and the tendencies in the configuration of the daily schedules and the modal operational indicators are established. Probabilistic and statistical models of the loads of substations are developed. Adequate regression models of the daily schedules of reactive loads of substations are obtained.

  10. 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.

  11. Operation of the matrix converter as energy sources link of variable voltage; Operacion del convertidor matricial como enlace de fuentes de energia de voltaje variable

    Energy Technology Data Exchange (ETDEWEB)

    Lozano-Garcia, J. M; Hernandez-Figueroa, M. A; Estrada Garcia, H. J; Martinez-Patino, J [Universidad de Guanajuato, Campus Irapuato-Salamanca, Salamanca, Guanajuato (Mexico)]. E-mails: jm.lozano@ugto.mx; mahf@ugto.mx; hestrada@ugto.mx; jesusmp23@ugto.mx

    2013-03-15

    Renewable energy technologies, as wind turbines, have had a remarkable penetration in power systems worldwide, causing that actual power grids became dependent and vulnerable to the variability of the energy generated by this type of resource. In that sense, power converters provide a crucial function in the performance of the overall electrical system when they are used as links between this type of generators and the power system. In this paper, a matrix converter is proposed as link device, to cope with distorted and variable voltages as the ones found in wind turbines operation where generated voltages are directly dependent on wind's speed. An analysis of its main functional characteristics when it operates subject to distorted input-voltage condition, in order to synthesize a set of output voltages with constant magnitude and frequency and without harmonic distortion, is presented. Numerical simulations and experimental results from a laboratory-scale prototype are presented to validate the converter performance. [Spanish] La gran penetracion que ha tenido la generacion de energia mediante recursos renovables, como los generadores eolicos, en el mercado energetico, han ocasionado que las redes electricas sean mas dependientes y vulnerables a la variabilidad de la energia que se genera con este tipo de recursos. En ese sentido, los convertidores de potencia utilizados como enlace entre este tipo de generadores y el sistema electrico son determinantes en el comportamiento final que se tendra en el sistema electrico. En el presente trabajo se propone la utilizacion del convertidor matricial como dispositivo de enlace y se analizan sus caracteristicas operativas en casos donde se requiere la generacion de senales de voltaje sinusoidales y con valores constantes tanto en magnitud como en frecuencia a partir de senales variables, situacion que se presenta comunmente en los aerogeneradores donde el voltaje generado depende directamente de la velocidad del

  12. Ultra-low Voltage CMOS Cascode Amplifier

    DEFF Research Database (Denmark)

    Lehmann, Torsten; Cassia, Marco

    2000-01-01

    In this paper, we design a folded cascode operational transconductance amplifier in a standard CMOS process, which has a measured 69 dB DC gain, a 2 MHz bandwidth and compatible input- and output voltage levels at a 1 V power supply. This is done by a novel Current Driven Bulk (CDB) technique...

  13. 40 CFR 141.626 - Operational evaluation levels.

    Science.gov (United States)

    2010-07-01

    ... operational evaluation and submit a written report of the evaluation to the State no later than 90 days after... written report must be made available to the public upon request. (2) Your operational evaluation must... scope of evaluation in writing and you must keep that approval with the completed report....

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

    Directory of Open Access Journals (Sweden)

    F. Gharedaghi

    2011-11-01

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

  15. Space Electronics Operating at High Temperatures and Radiation Levels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposal represents a radical revolution in Power Management & Distribution (PMAD) that addresses many of the challenges for NASA missions that will operate...

  16. Research on High-voltage Transmission Line Operation and Maintenance Management%对高压输电线路运维管理的研究

    Institute of Scientific and Technical Information of China (English)

    刘子新

    2014-01-01

    With the development of economy and society, industrial electricity and electricity consumption are increasing;therefore, we must pay attention to the maintenance of high voltage transmission lines run management. Doing work related to the management, to ensure the normal operation of high voltage transmission lines, it is possible for the development of people's life, work and social economy to lay a good foundation.%随着经济社会的不断发展,工业用电和生活用电都在不断增加,所以,必须要重视高压输电线路的运行维护管理工作。做好相关的管理工作,确保高压输电线路的正常运行,能够为人们的生活、工作和社会经济的发展奠定良好的基础。

  17. Voltage scheduling for low power/energy

    Science.gov (United States)

    Manzak, Ali

    2001-07-01

    Power considerations have become an increasingly dominant factor in the design of both portable and desk-top systems. An effective way to reduce power consumption is to lower the supply voltage since voltage is quadratically related to power. This dissertation considers the problem of lowering the supply voltage at (i) the system level and at (ii) the behavioral level. At the system level, the voltage of the variable voltage processor is dynamically changed with the work load. Processors with limited sized buffers as well as those with very large buffers are considered. Given the task arrival times, deadline times, execution times, periods and switching activities, task scheduling algorithms that minimize energy or peak power are developed for the processors equipped with very large buffers. A relation between the operating voltages of the tasks for minimum energy/power is determined using the Lagrange multiplier method, and an iterative algorithm that utilizes this relation is developed. Experimental results show that the voltage assignment obtained by the proposed algorithm is very close (0.1% error) to that of the optimal energy assignment and the optimal peak power (1% error) assignment. Next, on-line and off-fine minimum energy task scheduling algorithms are developed for processors with limited sized buffers. These algorithms have polynomial time complexity and present optimal (off-line) and close-to-optimal (on-line) solutions. A procedure to calculate the minimum buffer size given information about the size of the task (maximum, minimum), execution time (best case, worst case) and deadlines is also presented. At the behavioral level, resources operating at multiple voltages are used to minimize power while maintaining the throughput. Such a scheme has the advantage of allowing modules on the critical paths to be assigned to the highest voltage levels (thus meeting the required timing constraints) while allowing modules on non-critical paths to be assigned

  18. Aqueous Solution-Deposited Gallium Oxide Dielectric for Low-Temperature, Low-Operating-Voltage Indium Oxide Thin-Film Transistors: A Facile Route to Green Oxide Electronics.

    Science.gov (United States)

    Xu, Wangying; Cao, Hongtao; Liang, Lingyan; Xu, Jian-Bin

    2015-07-15

    We reported a novel aqueous route to fabricate Ga2O3 dielectric at low temperature. The formation and properties of Ga2O3 were investigated by a wide range of characterization techniques, revealing that Ga2O3 films could effectively block leakage current even after annealing in air at 200 °C. Furthermore, all aqueous solution-processed In2O3/Ga2O3 TFTs fabricated at 200 and 250 °C showed mobilities of 1.0 and 4.1 cm2 V(-1) s(-1), on/off current ratio of ∼10(5), low operating voltages of 4 V, and negligible hysteresis. Our study represents a significant step toward the development of low-cost, low-temperature, and large-area green oxide electronics.

  19. Lowering the Operational Voltage of Single-Layer Polymer Electroluminescent Devices by Using CuOx Modifying Indium-Tin Oxide Electrode

    Institute of Scientific and Technical Information of China (English)

    ZHOU Xin-ran; ZHAO Xin-wen; HU Wen-ping

    2007-01-01

    In this study it is demonstrated that oxygen-plasma-generated CuOx can enhance the holes injection from ITO anode into polymer layer in single-layer polymer EL devices. The possible reason for this enhancement is because the ITO anode modified with CuOx possesses much higher work function than pure ITO anode, which reduces the barrier for hole-injection and further lowers the operational voltage of the polymer EL devices. The work function shift is probable due to the oxygen-plasma-generated CuOx can store more releasable oxygen, and the releasable oxygen in turn changes the oxygen concentration just near ITO surface, which will shift the work function of ITO anode.

  20. High-Level Operations in Nonprocedural Programming Languages.

    Science.gov (United States)

    1983-12-01

    defining type specific operators. Abstract data type has been applied to the nonprocedural language NOPAL [Sang8O]. It was primarily used as a tool...Navigation............24 Network data model. ...... 24 NEXT...............98, 100 Nonterminals .......... 118 NOPAL .............19 Optimization .......... 80

  1. Litter Pollution, Level 2. Teacher Guide. Operation Waste Watch.

    Science.gov (United States)

    Virginia State Dept. of Waste Management, Richmond. Div. of Litter & Recycling.

    Operation Waste Watch is a series of seven sequential learning units which addresses the subject of litter control and solid waste management. Each unit may be used in a variety of ways, depending on the needs and schedules of individual schools, and may be incorporated into various social studies, science, language arts, health, mathematics, and…

  2. Levels of Availability of a Formal Operational Strategy.

    Science.gov (United States)

    Stone, C. Addison; Day, Mary Carol

    1978-01-01

    A modified version of Inhelder's and Piaget's bending-rods task was administered twice in succession to 9-, 11-, and 13-year-olds. Subjects were then categorized as spontaneous, latent, or nonusers of the formal operational control-of-variables strategy according to whether they used the strategy on the first, second, or neither administration.…

  3. Capture of instantaneous temperature in oscillating flows: use of constant-voltage anemometry to correct the thermal lag of cold wires operated by constant-current anemometry.

    Science.gov (United States)

    Berson, Arganthaël; Poignand, Gaëlle; Blanc-Benon, Philippe; Comte-Bellot, Geneviève

    2010-01-01

    A new procedure for the instantaneous correction of the thermal inertia of cold wires operated by a constant-current anemometer is proposed for oscillating flows. The thermal inertia of cold wires depends both on the wire properties and on the instantaneous incident flow velocity. Its correction is challenging in oscillating flows because no relationship between flow velocity and heat transfer around the wire is available near flow reversal. The present correction procedure requires neither calibration data for velocity nor thermophysical or geometrical properties of the wires. The method relies on the splitting of the time lag of cold wires into two factors, which are obtained using a constant-voltage anemometer in the heated mode. The first factor, which is intrinsic to the wire, is deduced from time-constant measurements performed in a low-turbulence flow. The second factor, which depends on the instantaneous flow velocity, is acquired in situ. In oscillating flows, data acquisition can be synchronized with a reference signal so that the same wire is alternatively operated in the cold mode by a constant-current anemometer and in the heated mode by a constant-voltage anemometer. Validation experiments are conducted in an acoustic standing-wave resonator, for which the fluctuating temperature field along the resonator axis is known independently from acoustic pressure measurements, so that comparisons can be made with cold-wire measurements. It is shown that despite the fact that the wire experiences flow reversal, the new procedure recovers accurately the instantaneous temperature of the flow.

  4. Voltage Controlled Dynamic Demand Response

    DEFF Research Database (Denmark)

    Bhattarai, Bishnu Prasad; Bak-Jensen, Birgitte; Mahat, Pukar

    2013-01-01

    . An adaptive dynamic model has been developed to determine composite voltage dependency of an aggregated load on feeder level. Following the demand dispatch or control signal, optimum voltage setting at the LV substation is determined based on the voltage dependency of the load. Furthermore, a new technique...

  5. Fault Diagnosis and Fault-tolerant Control of Modular Multi-level Converter High-voltage DC System

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Wang, Chao

    2016-01-01

    Modular Multilevel Converter based High Voltage Direct Current (MMC-HVDC) configuration is a promising solution for the efficient grid integration and bulky power transmission over long distance. However, the large number of series connected identical modules in MMC may increase the probability...... strategies of MMC-HVDC systems for the most common faults happened in MMC-HVDC systems covering MMC faults, DC side faults as well as AC side faults. An important part of this paper is devoted to a discussion of the vulnerable spots as well as failure mechanism of the MMC-HVDC system covering switching...

  6. Firepower, Maneuver, and the Operational Level of War

    Science.gov (United States)

    1992-05-15

    wasn’t." Field Marshal Bernard Law Montgomery and General George S. Patton, two of the premier Allied field commanders in the European Theater of...higher headquarters and grafted onto another. Moreover, such changes are detrimental in a moral sense to the espirit and comradeship that most soldiers...Operation Barbarossa s-emed to exemplify "distrtbuted free maneuver" with three non-supporting thrusts into the Soviet Union , and with freGuent

  7. Optimization of power systems with voltage security constraints

    Science.gov (United States)

    Rosehart, William Daniel

    As open access market principles are applied to power systems, significant changes in their operation and control are occurring. In the new marketplace, power systems are operating under higher loading conditions as market influences demand greater attention to operating cost versus stability margins. Since stability continues to be a basic requirement in the operation of any power system, new tools are being considered to analyze the effect of stability on the operating cost of the system, so that system stability can be incorporated into the costs of operating the system. In this thesis, new optimal power flow (OPF) formulations are proposed based on multi-objective methodologies to optimize active and reactive power dispatch while maximizing voltage security in power systems. The effects of minimizing operating costs, minimizing reactive power generation and/or maximizing voltage stability margins are analyzed. Results obtained using the proposed Voltage Stability Constrained OPF formulations are compared and analyzed to suggest possible ways of costing voltage security in power systems. When considering voltage stability margins the importance of system modeling becomes critical, since it has been demonstrated, based on bifurcation analysis, that modeling can have a significant effect of the behavior of power systems, especially at high loading levels. Therefore, this thesis also examines the effects of detailed generator models and several exponential load models. Furthermore, because of its influence on voltage stability, a Static Var Compensator model is also incorporated into the optimization problems.

  8. Experimental Results of a DC Bus Voltage Level Control for a Load-Controlled Marine Current Energy Converter

    Directory of Open Access Journals (Sweden)

    Johan Forslund

    2015-05-01

    Full Text Available This paper investigates three load control methods for a  marine current energy converter using a vertical axis current  turbine (VACT mounted on a permanent magnet synchronous generator  (PMSG. The three cases are; a fixed AC load, a fixed pulse width  modulated (PWM DC load and DC bus voltage control of a DC  load. Experimental results show that the DC bus voltage control  reduces the variations of rotational speed by a factor of 3.5 at the cost  of slightly increased losses in the generator and transmission lines.  For all three cases, the tip speed ratio \\(\\lambda\\ can be kept close to  the expected \\(\\lambda_{opt}\\. The power coefficient is estimated to be  0.36 at \\(\\lambda_{opt}\\; however, for all three cases, the average  extracted power was about \\(\\sim 19\\\\%. A maximum power point  tracking (MPPT system, with or without water velocity measurement,  could increase the average extracted power.

  9. Operational Bright-Band Snow Level Detection Using Doppler Radar

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — A method to detect the bright-band snow level from radar reflectivity and Doppler vertical velocity data collection with an atmospheric profiling Doppler radar. The...

  10. Low Voltage Power Supply Incorporating Ceramic Transformer

    CERN Document Server

    Imori, M

    2007-01-01

    A low voltage power supply provides the regulated output voltage of 1 V from the supply voltage around 48 V. The low voltage power supply incorporates a ceramic transformer which utilizes piezoelectric effect to convert voltage. The ceramic transformer isolates the secondary from the primary, thus providing the ground isolation between the supply and the output voltages. The ceramic transformer takes the place of the conventional magnetic transformer. The ceramic transformer is constructed from a ceramic bar and does not include any magnetic material. So the low voltage power supply can operate under a magnetic field. The output voltage is stabilized by feedback. A feedback loop consists of an error amplifier, a voltage controlled oscillator and a driver circuit. The amplitude ratio of the transformer has dependence on the frequency, which is utilized to stabilize the output voltage. The low voltage power supply is investigated on the analogy of the high voltage power supply similarly incorporating the cerami...

  11. 30 CFR 18.47 - Voltage limitation.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Voltage limitation. 18.47 Section 18.47 Mineral... § 18.47 Voltage limitation. (a) A tool or switch held in the operator's hand or supported against his... particular voltage(s) are provided in the design and construction of the equipment, its wiring,...

  12. Mitigation of Voltage Swells by Static Series Compensator

    DEFF Research Database (Denmark)

    Awad, Hilmy; Blaabjerg, Frede

    2004-01-01

    is lower than a predetermined voltage level, the active power is employed to charge the ESC to this voltage level; 2) otherwise, the overvoltage protection of the SSC must operate. This paper also applies an overvoltage protection scheme based on a combination of a dc resistor with a chopper and the valves...... of the SSC. The design of the dc resistor is discussed. A 10 kV SSC experimental setup is exploited to carry out experiments in the case of balanced and unbalanced voltage swells at the grid side....

  13. Zero-Voltage Switching PWM Strategy Based Capacitor Current-Balancing Control for Half-Bridge Three-Level DC/DC Converter

    DEFF Research Database (Denmark)

    Liu, Dong; Deng, Fujin; Zhang, Qi

    2017-01-01

    The current imbalance among the two input capacitors is one of the important issues of the half-bridge threelevel (HBTL) DC/DC converter, which would affect system performance and reliability. In this paper, a zero-voltage switching (ZVS) pulse-wide modulation (PWM) strategy including two operation...... modes is proposed. Based on the proposed ZVS PWM strategy, a capacitor current-balancing control is proposed for the HBTL DC/DC converter, where the currents on the two input capacitors can be kept balanced by alternating the two operation modes of the proposed ZVS PWM strategy. Therefore, the proposed...... control strategy can improve the performance and reliability of the converter in the aspect of balancing the thermal stresses and lifetimes among the two input capacitors. Finally, simulation and experimental studies are conducted and results verify the proposed control strategy....

  14. CALCULATION OF OPERATING PARAMETERS OF HIGH-VOLTAGE POWER TAKE-OFF SYSTEM FOR THE PHOTOVOLTAIC FACILITY

    Directory of Open Access Journals (Sweden)

    R.V. Zaitsev

    2016-09-01

    Full Text Available Purpose. To ensure maximum production of electric power by photovoltaic vacilities, in addition to using highly efficient photovoltaic modules equipped with solar radiation concentrators must use a highly effective power take-off system. This paper is inscribed to solving the problem of a highly efficient and economic power take-off system development. Methodology. To solving the problem, we implemented three stages. On the first stage examines the dependence of electrical power from the intensity of the incident solar radiation. Based on this, the second stage is calculated the DC-DC converter resonant circuit and its working parameters, and developed circuit diagram of DC-DC converter. On the third stage, we carry out an analysis of power take-off system with step up DC-DC converter working. Results. In this paper, we carry out the analysis of working efficiency for photovoltaic facility power take-off system with step-up boost converter. The result of such analysis show that the efficiency of such system in a wide range of photovoltaic energy module illumination power is at 0.92, whereas the efficiency of classic power take-off systems does not exceed 0.70. Achieved results allow designing a circuit scheme of a controlled bridge resonant step-up converter with digital control. Proposed scheme will ensure reliable operation, fast and accurate location point of maximum power and conversion efficiency up to 0.96. Originality. Novelty of proposed power take-off system solution constitute in implementation of circuit with DC-DC converters, which as it shown by results of carrying out modeling is the most effective. Practical value. Practical implementation of proposed power take-off system design will allow reducing losses in connective wires and increasing the efficiency of such a system up to 92.5% in wide range of photovoltaic energy modules illumination.

  15. Fault Diagnosis and Fault-tolerant Control of Modular Multi-level Converter High-voltage DC System: A Review

    DEFF Research Database (Denmark)

    Liu, Hui; Ma, Ke; Wang, Chao;

    2016-01-01

    Modular Multilevel Converter based High Voltage Direct Current (MMC-HVDC) configuration is a promising solution for the efficient grid integration and bulky power transmission over long distance. However, the large number of series connected identical modules in MMC may increase the probability...... strategies of MMC-HVDC systems for the most common faults happened in MMC-HVDC systems covering MMC faults, DC side faults as well as AC side faults. An important part of this paper is devoted to a discussion of the vulnerable spots as well as failure mechanism of the MMC-HVDC system covering switching...... device fault, DC line faults as well as AC grid faults. Special attention is given to the comparison of the corresponding fault diagnosis and fault-tolerant control approaches. Further, focus is dedicated to control/protection strategies and topologies with fault ride-though capability for MMC...

  16. Low-Energy Real-Time OS Using Voltage Scheduling Algorithm for Variable Voltage Processors

    OpenAIRE

    Okuma, Takanori; Yasuura, Hiroto

    2001-01-01

    This paper presents a real-time OS based on $ mu $ITRON using proposed voltage scheduling algorithm for variable voltage processors which can vary supply voltage dynamically. The proposed voltage scheduling algorithms assign voltage level for each task dynamically in order to minimize energy consumption under timing constraints. Using the presented real-time OS, running tasks with low supply voltage leads to drastic energy reduction. In addition, the presented voltage scheduling algorithm is ...

  17. Experiment and Operation of a LHCD-35 kV/2.8 MW/1000 s High-Voltage Power Supply on HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    黄懿赟

    2002-01-01

    A -35 kV/2.8 MW/1000s high-voltage power supply (HVPS) for HT-7 superconducting tokamak has been built successfully. The HVPS is scheduled to run on a 2.45 GHz/1 MW lower hybrid current drive (LHCD) [1] system of HT-7 superconducting tokamak before the set-up of HT-7 superconducting tokamak in 2003. The HVPS has a series of advantages such as good steady and dynamic response, logical computer program controlling the HVPS without any fault, operational panel and experimental board for data acquisition, which both are grounded distinctively in a normative way to protect the main body of HVPS along with its attached equipments from dangers. Electric power cables and other control cables are disposed reasonably, to prevent signals from magnetic interference and ensure the precision of.signal transfer.This paper involves the experiment and operation of a 35 kV/2.8 MW/1000 s HVPS [2] for 2.45 GHz/1 MW LHCD system. The reliability and feasibility of the HVPS has been demonstrated in comparison with experimental results of original design and simulation data.

  18. Research on the Error Characteristics of a 110 kV Optical Voltage Transformer under Three Conditions: In the Laboratory, Off-Line in the Field and During On-Line Operation.

    Science.gov (United States)

    Xiao, Xia; Hu, Haoliang; Xu, Yan; Lei, Min; Xiong, Qianzhu

    2016-01-01

    Optical voltage transformers (OVTs) have been applied in power systems. When performing accuracy performance tests of OVTs large differences exist between the electromagnetic environment and the temperature variation in the laboratory and on-site. Therefore, OVTs may display different error characteristics under different conditions. In this paper, OVT prototypes with typical structures were selected to be tested for the error characteristics with the same testing equipment and testing method. The basic accuracy, the additional error caused by temperature and the adjacent phase in the laboratory, the accuracy in the field off-line, and the real-time monitoring error during on-line operation were tested. The error characteristics under the three conditions-laboratory, in the field off-line and during on-site operation-were compared and analyzed. The results showed that the effect of the transportation process, electromagnetic environment and the adjacent phase on the accuracy of OVTs could be ignored for level 0.2, but the error characteristics of OVTs are dependent on the environmental temperature and are sensitive to the temperature gradient. The temperature characteristics during on-line operation were significantly superior to those observed in the laboratory.

  19. 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

  20. Radiation levels in RE38 during nominal LHC operation

    CERN Document Server

    Presland, A

    2005-01-01

    Simulated radiation levels at the location of the electronic racks inside the RE38 alcove under nominal LHC running conditions are presented. The levels are expressed in terms of total dose [Gy], 1MeV equivalent neutrons fluence and the fluence of hadrons having energy in excess of 20 MeV. When the average loss rate around the ring is 1.65¥1011 m-1y-1 the annual dose inside an electronics rack in the alcove is 0.05 Gy [Si], the annual 1 MeV eq. neutron fluence is 5 x 108 per cm2 and the annual high energetic hadron fluence is 5 x 107 per cm2. A standard concrete shielding chicane identical to those used in all other alcoves inside the LHC tunnel would reduce the particle fluences with a factor 10.

  1. Seizing opportunities for change at the operational level.

    Science.gov (United States)

    Restrepo, Diana; Charron-Latour, Julie; Pourmonet, Hugo; Bassetto, Samuel

    2016-04-18

    Purpose - This paper presents a method for handling everyday opportunities for improvement, led by floor staff in healthcare institutions. More than 400,000 incidents and accidents were recorded in Quebec healthcare institutions in 2013. The burden of treatment falls on hospital floor staff. The purpose of this paper is to raise the visibility of this problem and support staff better in their efforts to handle opportunities for improvement. Design/methodology/approach - Based on issues identified in the literature, which have been found to exist in various organizations, the method involved reviewing practices in the field, proposing a solution, and testing it to assess its relevance and limitations. The method was tested in partnership with the Centre Hospitalier de l'Université de Montréal, in the internal medicine unit at Hôtel-Dieu campus. The test lasted three months. Indicators from this test have been compared to results in the literature. Findings - The proposed method presents a 68 per cent increase in ideas generated per person and per week compared to the reference study. The mean time for closing actions was about 41 per cent better (lower) than in the reference case. Research limitations/implications - The test lasted 15 weeks; a longer test is needed to collect more data. Practical implications - The first practical implication of this study was the creation of a method allowing employees to seize opportunities for improvement in their daily work. The application of this method revealed: first, the operational nature of the proposal (empowerment of the work team); second, the operationalization of continuous improvement (71 per cent of ideas were finalized while the initiative was monitored); third, the smooth operation of the mechanism for facilitating continuous improvement (organization of weekly meetings and team participation in these meetings in 90 per cent of cases); and fourth, a shared feeling that intra- and inter-team communication had

  2. 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.

  3. Invariance of visual operations at the level of receptive fields.

    Science.gov (United States)

    Lindeberg, Tony

    2013-01-01

    The brain is able to maintain a stable perception although the visual stimuli vary substantially on the retina due to geometric transformations and lighting variations in the environment. This paper presents a theory for achieving basic invariance properties already at the level of receptive fields. Specifically, the presented framework comprises (i) local scaling transformations caused by objects of different size and at different distances to the observer, (ii) locally linearized image deformations caused by variations in the viewing direction in relation to the object, (iii) locally linearized relative motions between the object and the observer and (iv) local multiplicative intensity transformations caused by illumination variations. The receptive field model can be derived by necessity from symmetry properties of the environment and leads to predictions about receptive field profiles in good agreement with receptive field profiles measured by cell recordings in mammalian vision. Indeed, the receptive field profiles in the retina, LGN and V1 are close to ideal to what is motivated by the idealized requirements. By complementing receptive field measurements with selection mechanisms over the parameters in the receptive field families, it is shown how true invariance of receptive field responses can be obtained under scaling transformations, affine transformations and Galilean transformations. Thereby, the framework provides a mathematically well-founded and biologically plausible model for how basic invariance properties can be achieved already at the level of receptive fields and support invariant recognition of objects and events under variations in viewpoint, retinal size, object motion and illumination. The theory can explain the different shapes of receptive field profiles found in biological vision, which are tuned to different sizes and orientations in the image domain as well as to different image velocities in space-time, from a requirement that the

  4. Bootstrapped Low-Voltage Analog Switches

    DEFF Research Database (Denmark)

    Steensgaard-Madsen, Jesper

    1999-01-01

    Novel low-voltage constant-impedance analog switch circuits are proposed. The switch element is a single MOSFET, and constant-impedance operation is obtained using simple circuits to adjust the gate and bulk voltages relative to the switched signal. Low-voltage (1-volt) operation is made feasible...

  5. Overvoltage Level and Influencing Factors of Yunnan-- Guangdong ± 800 kV DC Transmission Project in Islanded Operation Mode

    Institute of Scientific and Technical Information of China (English)

    CAI Hansheng; JIA Lei; CHEN Xipeng

    2012-01-01

    Overvoltage is one of the key factors influencing whether Yunnan--Guangdong UHVDC Project can be operated in Islanded Mode or not. Based on the on site test parameters of primary equipments and the actual control and protection system of the project, this paper performs calculations of the overvoltage level in islanded operation models. The influence of BLOCK process and load retard speed of Yunnan--Guangdong UHVDC on the overvoltage level in islanded mode is also studied. The results show that it is an important measure for suppressing the overvoltage level to switch off the converter transformer after ac filters have been switched off. The maximum per unit switching overvoltage is 1, 71 (reference value is 449 kV) under various fault conditions. The maximum transient overvoltage is 1.66(reference value is 318 kV), but its duration is short, The maximum transient recovery voltage across AC filter/capacitor bank circuit breakers is less than 1 300 kV. The arrester's absorption energy in the case of a bipolar BLOCK can be greatly reduced with the protection logic modified with respect to decreasing current characteristic, which was compared with the protection logic of direct load retard. It is favorable for the reduction of both, overvoltage and arrester~ s absorption energy, to lower the force retard speed in the case of bipolar ESOF command.

  6. Naval Operations: A Close Look at the Operational Level of War at Sea

    Science.gov (United States)

    2012-07-01

    actions explains to a large extent why capital-ship designs in the battleship era were so numerous, so experimental , and sometimes so foolish. The...operations are not poetry , and American perspectives are far from those of the Roman Empire, but this is not a time for U.S. leadership to be admired...campaign planning and testing. For example, it explicitly calls for training and experimentation .31 A cyberspace strategy and campaign plans are desirable

  7. The advantages and disadvantages of centralized control of air power at operational level

    Science.gov (United States)

    Arisoy, Uǧur

    2014-05-01

    People do not want to see and hear a war. In today's world, if war is inevitable, the use of air power is seen as the preferable means of conducting operations instead of financially burdensome land battles which are more likely to cause heavy loss of life. The use of Air Power has gained importance in NATO operations in the Post-Cold War era. For example, air power has undertaken a decisive role from the beginning to the end of the operation in Libya. From this point of view, the most important issue to consider is how to direct air power more effectively at operational level. NATO's Core JFAC (Joint Force Air Command) was established in 2012 to control joint air power at operational level from a single center. US had experienced JFAC aproach in the Operation Desert Storm in 1991. UK, France, Germany, Italy and Spain are also directing their air power from their JFAC structures. Joint air power can be directed from a single center at operational level by means of JFAC. JFAC aproach provides complex planning progress of Air Power to be controled faster in a single center. An Air Power with a large number of aircrafts, long range missiles of cutting-edge technology may have difficulties in achieving results unless directed effectively. In this article, directing air power more effectively at operational level has been studied in the framework of directing air power from a single center carried out by SWOT analysis technique. "Directing Air Power at operational level from a single center similar to JFAC-like structure" is compared with "Directing Air Power at operational level from two centers similar to AC (Air Command) + CAOC (Combined Air Operations Center) structure" As a result of this study, it is assessed that directing air power at operational level from a single center would bring effectiveness to the air campaign. The study examines directing air power at operational level. Developments at political, strategic and tactical levels have been ignored.

  8. Transient voltage sharing in series-coupled high voltage switches

    Directory of Open Access Journals (Sweden)

    Editorial Office

    1992-07-01

    Full Text Available For switching voltages in excess of the maximum blocking voltage of a switching element (for example, thyristor, MOSFET or bipolar transistor such elements are often coupled in series - and additional circuitry has to be provided to ensure equal voltage sharing. Between each such series element and system ground there is a certain parasitic capacitance that may draw a significant current during high-speed voltage transients. The "open" switch is modelled as a ladder network. Analy­sis reveals an exponential progression in the distribution of the applied voltage across the elements. Overstressing thus oc­curs in some of the elements at levels of the total voltage that are significantly below the design value. This difficulty is overcome by grading the voltage sharing circuitry, coupled in parallel with each element, in a prescribed manner, as set out here.

  9. A Low-Voltage CMOS Buffer for RF Applications Based on a Fully-Differential Voltage-Combiner

    OpenAIRE

    Abdollahvand, S.; Santos-Tavares, R.; Goes, João

    2013-01-01

    Part 20: Electronics: RF Applications; International audience; This paper presents a new CMOS buffer circuit topology for radio-frequency (RF) applications based on a fully-differential voltage-combiner circuit, capable of operating at low-voltage. The proposed circuit uses a combination of common-source (CS) and common-drain (CD) devices. The simulation results show good levels of linearity and bandwidth. To improve total harmonic distortion (THD) a source degeneration technique is used. The...

  10. High Efficiency Power Converter for Low Voltage High Power Applications

    DEFF Research Database (Denmark)

    Nymand, Morten

    , and remote power generation for light towers, camper vans, boats, beacons, and buoys etc. A review of current state-of-the-art is presented. The best performing converters achieve moderately high peak efficiencies at high input voltage and medium power level. However, system dimensioning and cost are often......The topic of this thesis is the design of high efficiency power electronic dc-to-dc converters for high-power, low-input-voltage to high-output-voltage applications. These converters are increasingly required for emerging sustainable energy systems such as fuel cell, battery or photo voltaic based...... determined by the performance at the system worst case operating point which is usually at minimum input voltage and maximum power. Except for the non-regulating V6 converters, all published solutions exhibit a very significant drop in conversion efficiency at minimum input voltage and maximum output power...

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

    Directory of Open Access Journals (Sweden)

    Masaharu Kobayashi

    2016-02-01

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

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

    Science.gov (United States)

    Kobayashi, Masaharu; Hiramoto, Toshiro

    2016-02-01

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

  13. Probabilistic Analysis for Capacity Planning in Smart Grid at Residential Low Voltage Level by Monte-Carlo Method

    NARCIS (Netherlands)

    Du, W.

    2011-01-01

    Smart Grid integrates sustainable energy sources and allows mutual communications between electricity distribution operators and electricity consumers. Electricity demand and supply becomes more complex in Smart Grid. It is more challenging for DNOs in grid asset capacity planning, especially at low

  14. Lowered operation voltage in Pt/SBi2Ta2O9/HfO2/Si ferroelectric-gate field-effect transistors by oxynitriding Si

    Science.gov (United States)

    Horiuchi, Takeshi; Takahashi, Mitsue; Li, Qiu-Hong; Wang, Shouyu; Sakai, Shigeki

    2010-05-01

    Oxynitrided Si (SiON) surfaces show smaller subthreshold swings than do directly nitrided Si (SiN) surfaces when used in ferroelectric-gate field-effect transistors (FeFETs) having the following stacked-gate structure: Pt/SrBi2Ta2O9(SBT)/HfO2/Si. SiON/Si substrates for FeFETs were prepared by rapid thermal oxidation (RTO) in O2 at 1000 °C and subsequent rapid thermal nitridation (RTN) in NH3 at various temperatures in the range 950-1150 °C. The electrical properties of the Pt/SBT/HfO2/SiON/Si FeFET were compared with those of reference FETs, i.e. Pt/SBT/HfO2 gate stacks formed on Si substrates subjected to various treatments: SiNx/Si formed by RTN, SiO2/Si formed by RTO and untreated Si. The Pt/SBT/HfO2/SiON/Si FeFET had a larger memory window than all the other reference FeFETs, particularly at low operation voltages when the RTN temperature was 1050 °C.

  15. Low driving voltage Mach-Zehnder interference modulator constructed from an electro-optic polymer on ultra-thin silicon with a broadband operation.

    Science.gov (United States)

    Sato, Hiromu; Miura, Hiroki; Qiu, Feng; Spring, Andrew M; Kashino, Tsubasa; Kikuchi, Takamasa; Ozawa, Masaaki; Nawata, Hideyuki; Odoi, Keisuke; Yokoyama, Shiyoshi

    2017-01-23

    An electro-optic (EO) polymer waveguide using an ultra-thin silicon hybrid has been designed and fabricated. The silicon core has the thickness of 50 nm and a width of 5 μm. The waveguide was completed after covering the cladding with the high temperature stable EO polymer. We have demonstrated a low half-wavelength voltage of 0.9 V at the wavelength of 1.55 μm by using a Mach-Zehnder interference modulator with TM mode operation. The measured modulation corresponded to an effective in-device EO coefficient of 165 pm/V. By utilizing the traveling-wave electrode on the modulator the high-frequency response was tested up to 40 GHz. The 3 dB modulation bandwidth was measured to be 23 GHz. In addition, the high frequency sideband spectral measurement revealed that a linear response of the modulation index against the RF power was confirmed up to 40 GHz signal.

  16. Research on the Error Characteristics of a 110 kV Optical Voltage Transformer under Three Conditions: In the Laboratory, Off-Line in the Field and During On-Line Operation

    Directory of Open Access Journals (Sweden)

    Xia Xiao

    2016-08-01

    Full Text Available Optical voltage transformers (OVTs have been applied in power systems. When performing accuracy performance tests of OVTs large differences exist between the electromagnetic environment and the temperature variation in the laboratory and on-site. Therefore, OVTs may display different error characteristics under different conditions. In this paper, OVT prototypes with typical structures were selected to be tested for the error characteristics with the same testing equipment and testing method. The basic accuracy, the additional error caused by temperature and the adjacent phase in the laboratory, the accuracy in the field off-line, and the real-time monitoring error during on-line operation were tested. The error characteristics under the three conditions—laboratory, in the field off-line and during on-site operation—were compared and analyzed. The results showed that the effect of the transportation process, electromagnetic environment and the adjacent phase on the accuracy of OVTs could be ignored for level 0.2, but the error characteristics of OVTs are dependent on the environmental temperature and are sensitive to the temperature gradient. The temperature characteristics during on-line operation were significantly superior to those observed in the laboratory.

  17. Research on the Error Characteristics of a 110 kV Optical Voltage Transformer under Three Conditions: In the Laboratory, Off-Line in the Field and During On-Line Operation

    Science.gov (United States)

    Xiao, Xia; Hu, Haoliang; Xu, Yan; Lei, Min; Xiong, Qianzhu

    2016-01-01

    Optical voltage transformers (OVTs) have been applied in power systems. When performing accuracy performance tests of OVTs large differences exist between the electromagnetic environment and the temperature variation in the laboratory and on-site. Therefore, OVTs may display different error characteristics under different conditions. In this paper, OVT prototypes with typical structures were selected to be tested for the error characteristics with the same testing equipment and testing method. The basic accuracy, the additional error caused by temperature and the adjacent phase in the laboratory, the accuracy in the field off-line, and the real-time monitoring error during on-line operation were tested. The error characteristics under the three conditions—laboratory, in the field off-line and during on-site operation—were compared and analyzed. The results showed that the effect of the transportation process, electromagnetic environment and the adjacent phase on the accuracy of OVTs could be ignored for level 0.2, but the error characteristics of OVTs are dependent on the environmental temperature and are sensitive to the temperature gradient. The temperature characteristics during on-line operation were significantly superior to those observed in the laboratory. PMID:27537895

  18. Reduction of RF accelerating voltage of Pohang Light Source-II superconducting RF cavity for stable top-up mode operation

    Science.gov (United States)

    Joo, Y.; Yu, I.; Park, I.; Chun, M. H.; Sohn, Y.

    2017-03-01

    The Pohang Light Source-II (PLS-II) is currently providing a top-up mode user-service operation with maximum available beam current of 400 mA and a beam emittance of below 10 nm-rad. The dimension of the beam bunch shortened to accomplish a low beam emittance of below 10 nm-rad from a high beam current of 400 mA increases the bunch charge density. As a result, the electron beam lifetime is significantly degraded and a high gradient of power is lost in the vacuum components of the storage ring. A study on how to reduce the bunch charge density without degrading beam emittance found that reducing the RF accelerating voltage (Vacc) can lower the bunch charge density by lengthening the bunch in the longitudinal direction. In addition, the Vacc required for stable operation with beam current of 400 mA can be reduced by lowering the external cavity quality factors (Qext values) of the superconducting cavities (SCs). To control the Qext values of SCs gradually without accessing the accelerator tunnel, a remote control motorized three-probe-tuner was installed in the transmission line of each SC. The optimum installation position of the three-probe-tuner was determined by using a finite-difference time-domain (FDTD) simulation and by experimenting on various installation positions of the three-probe-tuner. The Qext values of all the SCs were lowered to 1.40 × 105, and then, the Vacc required to store the beam current of 400 mA was decreased from 4.8 MV to 4.2 MV, which corresponds to 10% lengthening of the beam bunches. The stable operation with the reduced Vacc was confirmed during a 400 mA ten-day top-up mode user-service. Currently, the RF system of the PLS-II storage ring delivers the user-service operation with lowered Qext values to reduce the power loss at the vacuum components as well as the cryogenic heat load of SCs, and no significant problems have been found. This method of reducing the Vacc may also be applied in other synchrotron facilities.

  19. Analog IC techniques for low-voltage low-power electronics

    NARCIS (Netherlands)

    Serdijn, W.A.; Verhoeven, C.J.M.; Van Roermund, A.H.M.

    1995-01-01

    Analog IC Techniques lor Low-Voltage Low Power Electronics addresses many very important, but recent, techniques which enable electronics to operate at a low supply voltage and consume a minimum amount of power. Apart from investigations at the device, circuit and system levels, the book provides a

  20. Analog IC techniques for low-voltage low-power electronics

    NARCIS (Netherlands)

    Serdijn, W.A.; Verhoeven, C.J.M.; Van Roermund, A.H.M.

    1995-01-01

    Analog IC Techniques lor Low-Voltage Low Power Electronics addresses many very important, but recent, techniques which enable electronics to operate at a low supply voltage and consume a minimum amount of power. Apart from investigations at the device, circuit and system levels, the book provides a

  1. High-voltage air-core pulse transformers

    Energy Technology Data Exchange (ETDEWEB)

    Rohwein, G. J.

    1981-01-01

    General types of air core pulse transformers designed for high voltage pulse generation and energy transfer applications are discussed with special emphasis on pulse charging systems which operate up to the multi-megavolt range. The design, operation, dielectric materials, and performance are described. It is concluded that high voltage air core pulse transformers are best suited to applications outside the normal ranges of conventional magnetic core transformers. In general these include charge transfer at high power levels and fast pulse generation with comparatively low energy. When properly designed and constructed, they are capable of delivering high energy transfer efficiency and have demonstrated superior high voltage endurance. The principal disadvantage of high voltage air core transformers is that they are not generally available from commercial sources. Consequently, the potential user must become thoroughly familiar with all aspects of design, fabrication and system application before he can produce a high performance transformer system. (LCL)

  2. Increasing the open circuit voltage of bulk-heterojunction solar cells by raising the LUMO level of the acceptor

    NARCIS (Netherlands)

    Kooistra, Floris B.; Knol, Joop; Kastenberg, Fredrik; Popescu, Lacramioara M.; Verhees, Wiljan J. H.; Kroon, Jan M.; Hummelen, Jan C.

    2007-01-01

    We report the synthesis, characterization, and electrochemical properties of ten new fullerene derivatives for usage in organic solar cells. The phenyl ring of PCBM was substituted with electron-donating and electron-withdrawing substituents to study their influence on the LUMO level of the parent f

  3. A cost benefit operator for efficient multi level genetic algorithm searches

    OpenAIRE

    Mitchell, George G.; McMullin, Barry; Decraene, James

    2007-01-01

    In this paper we present a novel cost benefit operator that assists multi level genetic algorithm searches. Through the use of the cost benefit operator, it is possible to dynamically constrain the search of the base level genetic algorithm, to suit the user’s requirements. Initially we review meta-evolutionary (multi-level genetic algorithm) approaches. We note that the current literature has abundant studies on meta-evolutionary GAs. However these approaches have not identified an effici...

  4. Effects of octreotide on expression of L-type voltage-operated calcium channels and on intracellular Ca2+ in activated hepatic stellate cells

    Institute of Scientific and Technical Information of China (English)

    丁惠国; 王宝恩; 贾继东; 夏华向; 王振宇; 赵春惠; 徐燕琳

    2004-01-01

    Background The contractility of hepatic stellate cells (HSCs) may play an important role in the pathogenesis of cirrhosis with portal hypertension. The aim of this study was to research the effects of octreotide, an analogue of somatostatin, on intracellular Ca2+ and on the expression of L-type voltage-operated calcium channels (L-VOCCs) in activated HSCs, and to try to survey the use of octreotide in treatment and prevention of cirrhosis with portal hypertension complications. Methods HSC-T6, an activated HSCs line, was plated on small glass coverslips in 35-mm culture dishes at a density of 1×105/ml, and incubated in DMEM media for 24 hours. After the cells were loaded with Fluo-3/AM, intracellular Ca2+ was measured by Laser Scanning Confocal Microscopy (LSCM). The dynamic changes in activated HSCs of intracellular Ca2+, stimulated by octreotide, endothelin-1, and KCl, respectively, were also determined by LSCM. Each experiment was repeated six times. L-VOCC expression in HSCs was estimated by immunocytochemistry. Results After octreotide stimulation, a signifcant decrease in the intracellular Ca2+ of activated HSCs was observed. However, octreotide did not inhibit the increases in intracellular Ca2+ after stimulation by KCl and endothelin-1. Moreover, octreotide did not significantly affect L-VOCC expression. These results suggest that neither L-VOCC nor endothelin-1 receptors in activated HSCs are inhibited by octreotide. Conclusions Octreotide may decrease portal hypertension and intrahepatic vascular tension by inhibiting activated HSCs contractility through decreases in intracellular Ca2+. The somatostatin receptors in activated HSCs may be inhibited by octreotide.

  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. High perfomance selectable value transportable high dc Voltage standard

    CERN Document Server

    Galliana, Flavio; Tet, Luca Roncaglione

    2016-01-01

    At National Institute of Metrological Research (INRIM), a selectable-value Transportable High dcVoltage Standard (THVS) operating in the range from 10 V to 100 V in steps of 10 V, was developed. This Standard was built to cover the lack of high level dc Voltage Standards at voltages higher than 10 V to employ as laboratory (local) or travelling Standards for Inter-Laboratory Comparisons (ILCs). A ground-mobile electronic technique was used to enhance the accuracy of the THVS at the higher values. The THVS shows better noise, better short-mid-term stability than top level dc Voltage and multifunction calibrators (MFCs) and better suitability and insensibility to be transported than these instruments. The project is extensible to 1000 V.

  7. The Tera Two-Level Operating System. Revision 1.2.

    Science.gov (United States)

    2007-11-02

    The Tera computer hardware provides for four privilege levels. These privilege levels are used to protect various parts of the system from each other...are for normal use by the operating system (OS). This document describes some of the motivation for using two privilege levels in the OS and discusses the way such an OS is built using the Tera tools.

  8. An investigation into soft error detection efficiency at operating system level.

    Science.gov (United States)

    Asghari, Seyyed Amir; Kaynak, Okyay; Taheri, Hassan

    2014-01-01

    Electronic equipment operating in harsh environments such as space is subjected to a range of threats. The most important of these is radiation that gives rise to permanent and transient errors on microelectronic components. The occurrence rate of transient errors is significantly more than permanent errors. The transient errors, or soft errors, emerge in two formats: control flow errors (CFEs) and data errors. Valuable research results have already appeared in literature at hardware and software levels for their alleviation. However, there is the basic assumption behind these works that the operating system is reliable and the focus is on other system levels. In this paper, we investigate the effects of soft errors on the operating system components and compare their vulnerability with that of application level components. Results show that soft errors in operating system components affect both operating system and application level components. Therefore, by providing endurance to operating system level components against soft errors, both operating system and application level components gain tolerance.

  9. 78 FR 57585 - Minimum Training Requirements for Entry-Level Commercial Motor Vehicle Operators

    Science.gov (United States)

    2013-09-19

    ... Federal Motor Carrier Safety Administration 49 CFR Parts 380, 383, and 384 RIN 2126-AB06 Minimum Training Requirements for Entry-Level Commercial Motor Vehicle Operators AGENCY: Federal Motor Carrier Safety... applying for a commercial driver's license (CDL) to operate commercial motor vehicles (CMVs) in...

  10. 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.

  11. Probing the Energy Level Alignment and the Correlation with Open-Circuit Voltage in Solution-Processed Polymeric Bulk Heterojunction Photovoltaic Devices.

    Science.gov (United States)

    Yang, Qing-Dan; Li, Ho-Wa; Cheng, Yuanhang; Guan, Zhiqiang; Liu, Taili; Ng, Tsz-Wai; Lee, Chun-Sing; Tsang, Sai-Wing

    2016-03-23

    Energy level alignment at the organic donor and acceptor interface is a key to determine the photovoltaic performance in organic solar cells, but direct probing of such energy alignment is still challenging especially for solution-processed bulk heterojunction (BHJ) thin films. Here we report a systematic investigation on probing the energy level alignment with different approaches in five commonly used polymer:[6,6]-phenyl-C71-butyric acid methyl ester (PCBM) BHJ systems. We find that by tuning the weight ratio of polymer to PCBM the electronic features from both polymer and PCBM can be obtained by photoemission spectroscopy. Using this approach, we find that some of the BHJ blends simply follow vacuum level alignment, but others show strong energy level shifting as a result of Fermi level pinning. Independently, by measuring the temperature-dependent open-circuit voltage (VOC), we find that the effective energy gap (Eeff), the energy difference between the highest occupied molecular orbital of the polymer donor (EHOMO-D) and lowest unoccupied molecular orbital of the PCBM acceptor (ELUMO-A), obtained by photoemission spectroscopy in all polymer:PCBM blends has an excellent agreement with the extrapolated VOC at 0 K. Consequently, the photovoltage loss of various organic BHJ photovoltaic devices at room temperature is in a range of 0.3-0.6 V. It is believed that the demonstrated direct measurement approach of the energy level alignment in solution-processed organic BHJ will bring deeper insight into the origin of the VOC and the corresponding photovoltage loss mechanism in organic photovoltaic cells.

  12. Adaptive Voltage Management Enabling Energy Efficiency in Nanoscale Integrated Circuits

    Science.gov (United States)

    Shapiro, Alexander E.

    Battery powered devices emphasize energy efficiency in modern sub-22 nm CMOS microprocessors rendering classic power reduction solutions not sufficient. Classical solutions that reduce power consumption in high performance integrated circuits are superseded with novel and enhanced power reduction techniques to enable the greater energy efficiency desired in modern microprocessors and emerging mobile platforms. Dynamic power consumption is reduced by operating over a wide range of supply voltages. This region of operation is enabled by a high speed and power efficient level shifter which translates low voltage digital signals to higher voltages (and vice versa), a key component that enables communication among circuits operating at different voltage levels. Additionally, optimizing the wide supply voltage range of signals propagating across long interconnect enables greater energy savings. A closed-form delay model supporting wide voltage range is developed to enable this capability. The model supports an ultra-wide voltage range from nominal voltages to subthreshold voltages, and a wide range of repeater sizes. To mitigate the drawback of lower operating speed at reduced supply voltages, the high performance exhibited by MOS current mode logic technology is exploited. High performance and energy efficient circuits are enabled by combining this logic style with power efficient near threshold circuits. Many-core systems that operate at high frequencies and process highly parallel workloads benefit from this combination of MCML with NTC. Due to aggressive scaling, static power consumption can in some cases overshadow dynamic power. Techniques to lower leakage power have therefore become an important objective in modern microprocessors. To address this issue, an adaptive power gating technique is proposed. This technique utilizes high levels of granularity to save additional leakage power when a circuit is active as opposed to standard power gating that saves static

  13. GEM voltage supply and real-time monitoring

    CERN Document Server

    Karaventzas, Vasilios Dimitris

    2015-01-01

    The operation of a GEM requires strong electrical fields that are able to initiate an electron avalanche. These electrical fields are generated by the application of high voltage in µm gaps. The scope of this project was to monitor the electrical parameters of the applied voltages, such as level and current flowing towards the detector. Therefore a real-time monitoring scheme was implemented. Additionally, a scheme for having all the voltages required for the operation of a GEM controllable, is proposed. The work conducted during this time-frame was targeted into developing the necessary parts for the operation of such device, whereas the integration of those into one functional circuit is to be conducted in a future work.

  14. A Refined Self-Tuning Filter-Based Instantaneous Power Theory Algorithm for Indirect Current Controlled Three-Level Inverter-Based Shunt Active Power Filters under Non-sinusoidal Source Voltage Conditions

    Directory of Open Access Journals (Sweden)

    Yap Hoon

    2017-02-01

    Full Text Available In this paper, a refined reference current generation algorithm based on instantaneous power (pq theory is proposed, for operation of an indirect current controlled (ICC three-level neutral-point diode clamped (NPC inverter-based shunt active power filter (SAPF under non-sinusoidal source voltage conditions. SAPF is recognized as one of the most effective solutions to current harmonics due to its flexibility in dealing with various power system conditions. As for its controller, pq theory has widely been applied to generate the desired reference current due to its simple implementation features. However, the conventional dependency on self-tuning filter (STF in generating reference current has significantly limited mitigation performance of SAPF. Besides, the conventional STF-based pq theory algorithm is still considered to possess needless features which increase computational complexity. Furthermore, the conventional algorithm is mostly designed to suit operation of direct current controlled (DCC SAPF which is incapable of handling switching ripples problems, thereby leading to inefficient mitigation performance. Therefore, three main improvements are performed which include replacement of STF with mathematical-based fundamental real power identifier, removal of redundant features, and generation of sinusoidal reference current. To validate effectiveness and feasibility of the proposed algorithm, simulation work in MATLAB-Simulink and laboratory test utilizing a TMS320F28335 digital signal processor (DSP are performed. Both simulation and experimental findings demonstrate superiority of the proposed algorithm over the conventional algorithm.

  15. 有载调压分接开关运行与异常状态分析%Operation and the Abnormal State of Load Voltage Regulation Tap

    Institute of Scientific and Technical Information of China (English)

    员学军

    2011-01-01

    本文介绍了CV型有载调压分接开关的动作原理、电压变化过程,对有载调压分接开关异常情况进行了汇总分析,强调了加强状态检修与维护的要点,并提出了一些有价值的建议.%This paper introduces the action principle of CV-type load voltage regulation tap, the change process of voltage, summarizes the abnormal situations of load voltage regulation tap, emphasizes the main points of the state repair and maintenance, and made some valuable suggestions.

  16. Study Results on Knowledge Requirements for Entry-Level Airport Operations and Management Personnel

    Science.gov (United States)

    Quilty, Stephen M.

    2005-01-01

    This paper identifies important topical knowledge areas required of individuals employed in airport operations and management positions. A total of 116 airport managers and airfield operations personnel responded to a survey that sought to identify the importance of various subject matter for entry level airport operations personnel. The results from this study add to the body of research on aviation management curriculum development and can be used to better develop university curriculum and supplemental training focused on airport management and operations. Recommendations are made for specialized airport courses within aviation management programs. Further, this study identifies for job seekers or individuals employed in entry level positions those knowledge requirements deemed important by airport managers and operations personnel at different sized airports.

  17. Research and Application of a Variety of Meteorology and Environment Monitoring and Early Warning Model about High Voltage Transmission Line’ s Operating Conditions%高压线路运行环境监测预警研究

    Institute of Scientific and Technical Information of China (English)

    杨莉; 赵薇; 沈映泉; 罗学礼; 王森

    2014-01-01

    With the transmission line condition monitoring of the fine level continues to increase,the research on a variety of envi-ronmental information model which is combination of different environmental factors and is established from the perspective of fusion analysis about multiple data is needed� For the Yunnan-specific environmental factors,this paper established fires and ice monito-ring and early warning model based on temperature,humidity,wind speed and other factors� This model monitoring and early warn-ing the high-voltage transmission Yunnan line operating condition� Practical application shows that the early warning model is accu-rately and efficiently,which can effectively cover an iceberg early warning fire and other disasters,in order to protect the safety and stable operation of transmission lines.%介绍从多种数据融合分析的角度建立开展多种环境信息模型的研究�本文针对云南省特有的环境因素,建立了基于温度、湿度、风速等因素的覆冰和山火监测预警模型,对云南省高压输电线路运行工况进行监测预警,实际应用表明预警模型精确有效,能够有效地对覆冰山火等灾害进行预警,从而保障输电线路的安全稳定运行。

  18. Varying Levels of Automation on UAS Operator Responses to Traffic Resolution Advisories in Civil Airspace

    Science.gov (United States)

    Kenny, Caitlin; Fern, Lisa

    2012-01-01

    Continuing demand for the use of Unmanned Aircraft Systems (UAS) has put increasing pressure on operations in civil airspace. The need to fly UAS in the National Airspace System (NAS) in order to perform missions vital to national security and defense, emergency management, and science is increasing at a rapid pace. In order to ensure safe operations in the NAS, operators of unmanned aircraft, like those of manned aircraft, may be required to maintain separation assurance and avoid loss of separation with other aircraft while performing their mission tasks. This experiment investigated the effects of varying levels of automation on UAS operator performance and workload while responding to conflict resolution instructions provided by the Tactical Collision Avoidance System II (TCAS II) during a UAS mission in high-density airspace. The purpose of this study was not to investigate the safety of using TCAS II on UAS, but rather to examine the effect of automation on the ability of operators to respond to traffic collision alerts. Six licensed pilots were recruited to act as UAS operators for this study. Operators were instructed to follow a specified mission flight path, while maintaining radio contact with Air Traffic Control and responding to TCAS II resolution advisories. Operators flew four, 45 minute, experimental missions with four different levels of automation: Manual, Knobs, Management by Exception, and Fully Automated. All missions included TCAS II Resolution Advisories (RAs) that required operator attention and rerouting. Operator compliance and reaction time to RAs was measured, and post-run NASA-TLX ratings were collected to measure workload. Results showed significantly higher compliance rates, faster responses to TCAS II alerts, as well as less preemptive operator actions when higher levels of automation are implemented. Physical and Temporal ratings of workload were significantly higher in the Manual condition than in the Management by Exception and

  19. Simulation of Transient Voltage Security of Large-Scale Power Grid Under Three-Level Voltage Control System and Its Control Strategy%三级电压控制体系下大电网暂态电压安全仿真及其控制策略

    Institute of Scientific and Technical Information of China (English)

    杨银国; 林舜江; 欧阳逸风; 刘明波; 温柏坚; 辛拓

    2013-01-01

      在Matlab环境下,借助电力系统分析工具箱(PSAT)实现了包含三级电压控制系统的大电网动态时域仿真,并分析其对广东电网暂态电压安全性的影响。结果表明该系统的二级电压控制紧急动作模式虽然有利于广东电网故障后的暂态电压恢复,但不能阻止暂态电压不安全事故的发生。进而,建立了针对暂态电压不安全故障的紧急切负荷控制优化模型,通过采用轨迹灵敏度法将动态优化模型转化为线性规划模型以获得紧急切负荷控制策略,动态仿真结果验证了所得控制策略能够使广东电网在严重故障后恢复暂态电压安全。%In Matlab environment and using power system analysis tools (PSAT) software, the dynamic time-domain simulation of large-scale power grid with three-level voltage control system is implemented, and the influences of three-level voltage control system on transient voltage security of Guangdong power grid are analyzed. Analysis results show that the emergency action mode of secondary voltage control in the three-level voltage control system contributes to the post-fault transient voltage recovery of load buses in Guangdong power grid, however it cannot prevent the occurrence of transient voltage insecurity. For this reason, in allusion to transient voltage insecurity accident an optimal control strategy for emergency load shedding, in which the trajectory sensitivity is utilized to turn the dynamic optimal model into linear programming model to achieve emergency load shedding control strategy, is established, and it is verified by dynamic simulation that after serious fault the transient voltage security of Guangdong power grid can be recovered by the achieved control strategy.

  20. Voltage Sensors Monitor Harmful Static

    Science.gov (United States)

    2009-01-01

    A tiny sensor, small enough to be worn on clothing, now monitors voltage changes near sensitive instruments after being created to alert Agency workers to dangerous static buildup near fuel operations and avionics. San Diego s Quasar Federal Systems received a Small Business Innovation Research (SBIR) contract from Kennedy Space Center to develop its remote voltage sensor (RVS), a dime-sized electrometer designed to measure triboelectric changes in the environment. One of the unique qualities of the RVS is that it can detect static at greater distances than previous devices, measuring voltage changes from a few centimeters to a few meters away, due to its much-improved sensitivity.

  1. Voltage balancing strategies for serial connection of microbial fuel cells

    Science.gov (United States)

    Khaled, Firas; Ondel, Olivier; Allard, Bruno; Buret, François

    2015-07-01

    The microbial fuel cell (MFC) converts electrochemically organic matter into electricity by means of metabolisms of bacteria. The MFC power output is limited by low voltage and low current characteristics in the range of microwatts or milliwatts per litre. In order to produce a sufficient voltage level (>1.5 V) and sufficient power to supply real applications such as autonomous sensors, it is necessary to either scale-up one single unit or to connect multiple units together. Many topologies of connection are possible as the serial association to improve the output voltage, or the parallel connection to improve the output current or the series/parallel connection to step-up both voltage and current. The association of MFCs in series is a solution to increase the voltage to an acceptable value and to mutualize the unit's output power. The serial association of a large number of MFCs presents several issues. The first one is the hydraulic coupling among MFCs when they share the same substrate. The second one is the dispersion between generators that lead to a non-optimal stack efficiency because the maximum power point (MPP) operation of all MFCs is not permitted. Voltage balancing is a solution to compensate non-uniformities towards MPP. This paper presents solutions to improve the efficiency of a stack of serially connected MFCs through a voltage-balancing circuit. Contribution to the topical issue "Electrical Engineering Symposium (SGE 2014)", edited by Adel Razek

  2. 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.

  3. 绕线式异步电动机调压节能运行研究%Research on the Operation Performance of Wound Rotor Asynchronous Motors in Voltage Regulation and Energy Saving

    Institute of Scientific and Technical Information of China (English)

    冯韧; 王兵; 侯黎平

    2016-01-01

    Based on the fact that asynchronous motors are characterized with periodic load operation, the optimal voltage of wound rotor asynchronous motors has been determined under no-load and light-load operating modes. With the load ratio a constant, the power factor under the optimal voltage is greater than that under the rated voltage. In light of the features of winding rotor asynchronous motors, a research has been conducted on the side series resistance starting and the capacity of voltage regulation and energy-saving series under series resistance speed regulation. When a resistance of 2 is connected in series with the rotor circuit, an accelerated starting of the motor has thus achieved. With the optimal voltage a constant, the electromagnetic torque remains constant before and after the series resistance has been connected with the rotor circuit. A step-down series resistance speed regulation model of wound rotor asynchronous motors has been set up to work out the relationship between the energy consumption of the rotor turn-on and rotor series resistance under a constant optimal voltage. When the load factor of the motor is in the range of 0%~50%, a certain energy-saving space could be obtained by appropriately reducing the power supply voltage, thus verifying the feasibility of the energy saving operation under the light load rotor series resistance voltage regulation of wound rotor asynchronous motors under the optimal voltage.%根据异步电动机带周期性负载运行的特点,确定了绕线式异步电动机处于空载、轻载运行状态下的最优电压,且维持负载率不变时,其在最优电压下的功率因数大于其在额定电压下的。针对绕线式异步电动机的特性,研究了其转子侧串电阻启动及串电阻调速下调压节能的运行状态,得知当转子回路中串入2电阻时,可加速电机启动,且在最优电压一定时,串电阻前后的电磁转矩恒定。通过搭建绕线式异步电动

  4. Improving transition voltage spectroscopy of molecular junctions

    DEFF Research Database (Denmark)

    Markussen, Troels; Chen, Jingzhe; Thygesen, Kristian Sommer

    2011-01-01

    Transition voltage spectroscopy (TVS) is a promising spectroscopic tool for molecular junctions. The principles in TVS is to find the minimum on a Fowler-Nordheim plot where ln(I/V2) is plotted against 1/V and relate the voltage at the minimum Vmin to the closest molecular level. Importantly, Vmin...... is approximately half the voltage required to see a peak in the dI/dV curve. Information about the molecular level position can thus be obtained at relatively low voltages. In this work we show that the molecular level position can be determined at even lower voltages, Vmin(α), by finding the minimum of ln...

  5. Quantifying the step following level of an operator in proceduralized scenarios

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Yoc Han; Jung, Wondea [KAERI, Daejeon (Korea, Republic of)

    2012-10-15

    In nuclear power plants, operators of the main control rooms cope with abnormal or emergency situations using relevant procedures. However, there exist several features that challenge step by step following of the procedures: ambiguous descriptions of procedures, dynamic situations of power plants, operational tendencies of operators, and so on. To identify and manage the features, it is useful to quantifying how compliantly an operator follows the steps of the procedures. There was little research that measures the step following level of an operator. Kim et al. presented a measure, VPP (variability of procedure progression), to estimate a variability of ways to follow a given procedure. However, VPP has some characteristics to be evaluated. First, VPP score is related with the number of step in each procedure progression. Second, VPP score is also affected by the number of progressions. In addition, VPP score implies a variability of procedure progressions, not a compliance of a progression with the given procedure. If all operators do not follow a sequence of steps in a procedure but show similar procedure progressions, the VPP score of the progressions will be low. Therefore, it is necessary to develop another measure that is capable to explain more closely the step following level. In this light, we propose a new measure, PCL (procedure compliance level) to estimate how a procedure progression is similar to the standard progressions. This paper introduces the algorithm of this measure and shows its applicability by presenting a result that is applied to a digitalized control room.

  6. Analysis of the Tesla transformer operation at the first half-wave of the output voltage taking into account ohmic losses

    Science.gov (United States)

    Palchikov, E. I.; Ryabchun, A. M.

    2016-06-01

    The speed and efficiency of the Tesla transformer at the first half-wave of the output voltage are studied as a function of the Q factors of the circuits and their coupling factor. Calculated results and experimental data are considered. It is shown that for given Q factors, there is an optimal value of the coupling factor providing the highest efficiency, which can be calculated and for which designers should work.

  7. 基于分区电网的多机进相调压效益探析%Voltage Regulation Effects of Leading phase Operation of Multi-generators in District Grids

    Institute of Scientific and Technical Information of China (English)

    韦延方; 卫志农; 孙国强; 王成亮

    2011-01-01

    发电机进相运行是解决系统低谷运行时枢纽点电压偏高的有效手段。针对江苏省2010年实际背景分区电网,选择若干组已投运的机组,以分类分区研究单机进相的调压作用为基础,对多机进相运行进行仿真,分析进相运行对分区关键母线电压的影响和对系统电压的调节作用,并校验多机进相运行时系统的暂态稳定性,探讨分区内多机进相运行的调压能力。%Leading phase operation of generators is an effective method to reduce voltage of the key point which is much high in valley load period.Several generating units in operation in the district grid of Jiangsu province in 2010 were selected as the research targets.Then the research analyzed the influence of leading phase of multi-generators on the key bus voltage based on the voltage regulation effects of leading phase of single-generator in classification and subarea method.The transient stability of leading phase of multi-generators was verified,and the voltage regulation capability of leading phase of multi-generators was analyzed.

  8. 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.

  9. On-chip High-Voltage Generator Design

    CERN Document Server

    Tanzawa, Toru

    2013-01-01

    This book describes high-voltage generator design with switched-capacitor multiplier techniques.  The author provides various design techniques for switched-capacitor on-chip high-voltage generators, including charge pump circuits, regulators, level shifters, references, and oscillators.  Readers will see these techniques applied to system design in order to address the challenge of how the on-chip high-voltage generator is designed for Flash memories, LCD drivers, and other semiconductor devices to optimize the entire circuit area and power efficiency with a low voltage supply, while minimizing the cost.   ·         Shows readers how to design charge pump circuits with lower voltage operation, higher power efficiency, and smaller circuit area; ·         Describes comprehensive circuits and systems design of on-chip high-voltage generators; ·         Covers all the component circuit blocks, including charge pumps, pump regulators, level shifters, oscillators, and references.

  10. SVPWM Technique with Varying DC-Link Voltage for Common Mode Voltage Reduction in a Matrix Converter and Analytical Estimation of its Output Voltage Distortion

    Science.gov (United States)

    Padhee, Varsha

    Common Mode Voltage (CMV) in any power converter has been the major contributor to premature motor failures, bearing deterioration, shaft voltage build up and electromagnetic interference. Intelligent control methods like Space Vector Pulse Width Modulation (SVPWM) techniques provide immense potential and flexibility to reduce CMV, thereby targeting all the afore mentioned problems. Other solutions like passive filters, shielded cables and EMI filters add to the volume and cost metrics of the entire system. Smart SVPWM techniques therefore, come with a very important advantage of being an economical solution. This thesis discusses a modified space vector technique applied to an Indirect Matrix Converter (IMC) which results in the reduction of common mode voltages and other advanced features. The conventional indirect space vector pulse-width modulation (SVPWM) method of controlling matrix converters involves the usage of two adjacent active vectors and one zero vector for both rectifying and inverting stages of the converter. By suitable selection of space vectors, the rectifying stage of the matrix converter can generate different levels of virtual DC-link voltage. This capability can be exploited for operation of the converter in different ranges of modulation indices for varying machine speeds. This results in lower common mode voltage and improves the harmonic spectrum of the output voltage, without increasing the number of switching transitions as compared to conventional modulation. To summarize it can be said that the responsibility of formulating output voltages with a particular magnitude and frequency has been transferred solely to the rectifying stage of the IMC. Estimation of degree of distortion in the three phase output voltage is another facet discussed in this thesis. An understanding of the SVPWM technique and the switching sequence of the space vectors in detail gives the potential to estimate the RMS value of the switched output voltage of any

  11. 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.

  12. Voltage-Sensitive Load Controllers for Voltage Regulation and Increased Load Factor in Distribution Systems

    DEFF Research Database (Denmark)

    Douglass, Philip James; Garcia-Valle, Rodrigo; Østergaard, Jacob

    2014-01-01

    consumption which can be mapped to temperature setpoint offsets of thermostat controlled loads. In networks where a lower voltage level corresponds to high system load (and vice versa), this controller acts to regulate voltage and increase the load factor. Simulations are conducted on low- and medium-voltage......This paper presents a novel controller design for controlling appliances based on local measurements of voltage. The controller finds the normalized voltage deviation accounting for the sensitivity of voltage measurements to appliance state. The controller produces a signal indicating desired power...... distribution systems with residential loads including voltage-sensitive water heaters. In low-voltage systems, the results of the simulations show the controller to be effective at reducing the extremes of voltage and increasing the load factor while respecting end-use temperature constraints. In medium-voltage...

  13. Assessment of nursing students' stress levels and coping strategies in operating room practice.

    Science.gov (United States)

    Yildiz Findik, Ummu; Ozbas, Ayfer; Cavdar, Ikbal; Yildizeli Topcu, Sacide; Onler, Ebru

    2015-05-01

    The aim of this study was to evaluate the stress levels and stress coping strategies of nursing students in their first operating room experience. This descriptive study was done with 126 nursing students who were having an experience in an operating room for the first time. Data were collected by using Personal Information Form, Clinical Stress Questionnaire, and Styles of Coping Inventory. The nursing students mostly had low clinical stress levels (M = 27.56, SD = 10.76) and adopted a self-confident approach in coping with stress (M = 14.3, SD = 3.58). The nursing students generally employed a helpless/self-accusatory approach among passive patterns as their clinical stress levels increased, used a self-confident and optimistic approach among active patterns as their average age increased, and those who had never been to an operating room previously used a submissive approach among passive patterns. The results showed that low levels of stress caused the nursing students to use active patterns in coping with stress, whereas increasing levels of stress resulted in employing passive patterns in stress coping. The nursing students should be ensured to maintain low levels of stress and use active patterns in stress coping.

  14. Accumulation of technological capabilities and operational performance improvement: evidence from a firm-level case study

    Directory of Open Access Journals (Sweden)

    Marcelio Fonseca

    2014-11-01

    Full Text Available Drawing on a single case study based on first-hand and long-term evidence gathered through extensive fieldwork, this article examines the process of technological capability accumulation and its implications for operational performance improvement in a chemical firm in Brazil (1980-2007. The evidence indicates that the efforts on technological capability accumulation, especially for innovative activities, permitted the case-study firm to improve its operational performance, notably in terms of technical and, to some extent, in terms of commercial indicators. This study contributes to advancing our understanding of relationship between the firm-level accumulation of technological capabilities and operational performance improvement. The study draws managers’ attention to the importance of managing and measuring a multiplicity of technological capabilities within firms and to the relevance of firm-level engineering-based innovative activities, normally neglected by policy makers.

  15. Installation and operation manual on sea level gauge (Model: NIO_Ghana_2004)

    Digital Repository Service at National Institute of Oceanography (India)

    Joseph, A; Pereira, A; VijayKumar, K.; Prabhudesai, S.; Methar, A; Dias, M.

    NIO sea level gauge is a pressure-based gauge that operates on 12 volts battery. The pressure-sensing element used in this gauge is a piezo-resistive programmable semiconductor transducer that provides pressure samples in RS-485 format...

  16. High Voltage Seismic Generator

    Science.gov (United States)

    Bogacz, Adrian; Pala, Damian; Knafel, Marcin

    2015-04-01

    This contribution describes the preliminary result of annual cooperation of three student research groups from AGH UST in Krakow, Poland. The aim of this cooperation was to develop and construct a high voltage seismic wave generator. Constructed device uses a high-energy electrical discharge to generate seismic wave in ground. This type of device can be applied in several different methods of seismic measurement, but because of its limited power it is mainly dedicated for engineering geophysics. The source operates on a basic physical principles. The energy is stored in capacitor bank, which is charged by two stage low to high voltage converter. Stored energy is then released in very short time through high voltage thyristor in spark gap. The whole appliance is powered from li-ion battery and controlled by ATmega microcontroller. It is possible to construct larger and more powerful device. In this contribution the structure of device with technical specifications is resented. As a part of the investigation the prototype was built and series of experiments conducted. System parameter was measured, on this basis specification of elements for the final device were chosen. First stage of the project was successful. It was possible to efficiently generate seismic waves with constructed device. Then the field test was conducted. Spark gap wasplaced in shallowborehole(0.5 m) filled with salt water. Geophones were placed on the ground in straight line. The comparison of signal registered with hammer source and sparker source was made. The results of the test measurements are presented and discussed. Analysis of the collected data shows that characteristic of generated seismic signal is very promising, thus confirms possibility of practical application of the new high voltage generator. The biggest advantage of presented device after signal characteristics is its size which is 0.5 x 0.25 x 0.2 m and weight approximately 7 kg. This features with small li-ion battery makes

  17. The high voltage homopolar generator

    Science.gov (United States)

    Price, J. H.; Gully, J. H.; Driga, M. D.

    1986-11-01

    System and component design features of proposed high voltage homopolar generator (HVHPG) are described. The system is to have an open circuit voltage of 500 V, a peak output current of 500 kA, 3.25 MJ of stored inertial energy and possess an average magnetic-flux density of 5 T. Stator assembly components are discussed, including the stator, mount structure, hydrostatic bearings, main and motoring brushgears and rotor. Planned operational procedures such as monitoring the rotor to full speed and operation with a superconducting field coil are delineated.

  18. Multi-Period Optimization for Voltage Control System in Transmission Grids

    DEFF Research Database (Denmark)

    Qin, Nan; Chen, Si; Liu, Chengxi

    2015-01-01

    Automatic Voltage Control (AVC) systems maintain the voltage in an acceptable range and minimize the power loss of the grid by coordinately regulating the controllable components. Switchable shunts and tap-able transformers are expected to be operated as few times as possible. This paper proposes....... In the lower level, the optimization is focused on the correction of the voltage violations every single minute based on data from the measurements and state estimation. The presented case study shows that the multi-period optimization in the upper level of AVC system can reduce adjustment times...

  19. Low voltage operating field effect transistors with composite In2O3-ZnO-ZnGa2O4 nanofiber network as active channel layer.

    Science.gov (United States)

    Choi, Seung-Hoon; Jang, Bong-Hoon; Park, Jin-Seong; Demadrille, Renaud; Tuller, Harry L; Kim, Il-Doo

    2014-03-25

    Field effect transistors (FETs), incorporating metal-oxide nanofibers as the active conductive channel, have the potential for driving the widespread application of nanowire or nanofiber FETs-based electronics. Here we report on low voltage FETs with integrated electrospun In2O3-ZnO-ZnGa2O4 composite fiber channel layers and high-K dielectric (MgO)0.3-(Bi1.5Zn1.0Nb1.5O7)0.7 gate insulator and compare their performance against FETs utilizing conductive single phase, polycrystalline ZnO or In2O3 channel layers. The polycrystalline In2O3-ZnO-ZnGa2O4 composite fibers provide superior performance with high field effect mobility (∼7.04 cm2 V(-1) s(-1)), low subthreshold swing (390 mV/dec), and low threshold voltage (1.0 V) combined with excellent saturation, likely resulting from the effective blocking of high current-flow through the In2O3 and ZnO nanocrystallites by the insulating spinel ZnGa2O4 phase. The microstructural evolution of the individual In2O3, ZnO, and ZnGa2O4 phases in composite fibers is clearly observed by high resolution TEM. A systematic examination of channel area coverage, ranging from single fiber to over 90% coverage, demonstrates that low coverage results in relatively low current outputs and reduced reproducibility which we attribute to the difficulty in positioning fibers and fiber length control. On the other hand, those with ∼80% coverage exhibited high field effect mobility, high on/off current ratios (>10(5)), and negligible hysteresis following 15 sweep voltage cycles. A special feature of this work is the application of the FETs to modulate the properties of complex polycrystalline nanocomposite channels.

  20. Prognostic value of pre-operative serum CA 15.3 levels in breast cancer.

    Science.gov (United States)

    Martín, Arancha; Corte, Ma Daniela; Alvarez, Ana Ma; Rodriguez, Juan Carlos; Andicoechea, Alejandro; Bongera, Miguel; Junquera, Sara; Pidal, Diego; Allende, Teresa; Muñiz, José L García; Vizoso, Francisco

    2006-01-01

    CA15.3 (also known as MUCI) is the most widely used marker in breast cancer. The aim of the present work was the evaluation of the prognostic value of preoperative serum CA15.3 levels in patients with primary breast cancer. This study included 818 women with a histologically verified diagnosis of invasive breast cancer. The serum values of CA15.3 were investigated at the time of primary diagnosis by means of an immunoradiometric assay based on the "sandwich" principle. The median follow-up period of patients free of recurrence was 38 months. Pre-operative CA15.3 serum levels ranged from 6 to 452 U/ml. Elevated CA15.3 levels (>30 U/ml) were found in 15.2% of patients. Statistical analysis showed that pre-operative CA15.3 serum levels were significantly higher in patients with large size tumors (T3 or T4) (p = 0.0001), as well as in those with node-positive tumors (p = 0.0001). In the univariate analysis, high CA15.3 levels were significantly associated with a lower probability of both relapse-free and overall survival in the overall group of patients (p = 0.0001 and p = 0.004, respectively) and in the subgroup with node-positive breast cancer (p = 0.001 and p = 0.03, respectively). In addition, multivariate analysis demonstrated that pre-operative levels of the antigen were significantly and independently associated with relapse-free survival in the overall group of patients, as well as in the subgroup of patients with node-positive breast cancer (p = 0.02 and p = 0.01, respectively). These results show that high pre-operative CA15.3 levels correlate with large size tumors and the presence of lymph node metastases and suggest that this antigen could be used as an additional prognostic marker.

  1. An ergonomics study of computerized emergency operating procedures: Presentation style, task complexity, and training level

    Energy Technology Data Exchange (ETDEWEB)

    Xu Song; Song Fei [Department of Industrial Engineering, Tsinghua University, Beijing 100084 (China); Li Zhizhong [Department of Industrial Engineering, Tsinghua University, Beijing 100084 (China)], E-mail: zzli@tsinghua.edu.cn; Zhao Qianyi; Luo Wei [Department of Industrial Engineering, Tsinghua University, Beijing 100084 (China); He Xuhong [Scanpower Risk Management China Inc., Towercrest International Plaza, No. 3 Maizidian West Road, Chaoyang District, Beijing 100016 (China); Salvendy, Gavriel [Department of Industrial Engineering, Tsinghua University, Beijing 100084 (China)

    2008-10-15

    Emergency operating procedures (EOPs) are widely used in nuclear power plants (NPPs). With the development of information technology, computerized EOPs are taking the place of paper-based ones. Unlike paper-based EOPs, the industrial practice of computerized EOPs is still quite limited. Ergonomics issues of computerized EOPs have not been studied adequately. This study focuses on the effects of EOP presentation style, task complexity, and training level on the performance of the operators in the execution of computerized EOPs. One simulated computerized EOP system was developed to present two EOPs, each with different task complexity levels, by two presentation styles (Style A: one- and two-dimensional flowcharts combination; Style B: two-dimensional flowchart and success logic tree combination). Forty subjects participated in the experiment of EOP execution using the simulated system. Statistical analysis of the experimental results indicates that: (1) complexity, presentation style, and training level all can significantly influence the error rate. High-complexity tasks and lack of sufficient training may lead to a higher error rate. Style B caused a significantly higher error rate than style A did in the skilled phase. So the designers of computerized procedures should take the presentation styles of EOPs into account. (2) Task complexity and training level can significantly influence operation time. No significant difference was found in operation time between the two presentation styles. (3) Training level can also significantly influence the subjective workload of EOPs operations. This implies that adequate training is very important for the performance of computerized EOPs even if emergency responses with computerized EOPs are much more simple and easy than that with paper-based EOPs.

  2. Research on SVPWM control scheme for NPC three-level inverter and balance of neural-point voltage%NPC型三电平逆变器SVPWM控制方法及中点电位平衡研究

    Institute of Scientific and Technical Information of China (English)

    李萍; 刘国忠

    2012-01-01

    二极管箝位型(NPC)三电平逆变器在中、高压大容量功率变换装置中的需求越来越迫切,目前已成为研究的热点.讨论利用功率开关所生成的不同电压矢量优化合成旋转参考空间电压矢量及各矢量作用时间分配的方案,实现SVPWM控制策略驱动逆变器;讨论实时改变控制负小矢量作用时间的系数以平衡直流侧母线中点电位的问题.仿真结果验证了NPC三电平逆变器SVPWM控制策略的正确性及中点电位平衡控制的有效性.%Diode NPC (neutral -point -clamped) three-level inverter is increasingly and urgently needed for medium to high-voltage and large-capacity power conversion devices, and becomes a research hot spot at present. Three voltage vectors generated by power switches are used to optimally synthesize space rotary reference voltage victors by assigned action time to each voltage vector to realize SVPWM inverter. Meanwhile, the DC neutral -point voltage of inverter is balanced thorough real-time adjusting action time of small negative vectors. The simulation results validate that the SVPWM scheme is correct for controlling NPC three -level inverter and the balance of neural-point voltage is effective.

  3. Phase diagrams and switching of voltage and magnetic field in dilute magnetic semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Escobedo, R. [Departamento de Matematica Aplicada y Ciencias de la Computacion, Universidad de Cantabria, 39005 Santander (Spain); Carretero, M.; Bonilla, L.L. [G. Millan Institute, Fluid Dynamics, Nanoscience and Industrial Maths., Universidad Carlos III de Madrid, 28911 Leganes (Spain); Unidad Asociada al Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco, Madrid (Spain); Platero, G. [Instituto de Ciencia de Materiales, CSIC, 28049 Cantoblanco, Madrid (Spain)

    2010-04-15

    The response of an n-doped dc voltage biased II-VI multi-quantum well dilute magnetic semiconductor nanostructure having its first well doped with magnetic (Mn) impurities is analyzed by sweeping wide ranges of both the voltage and the Zeeman level splitting induced by an external magnetic field. The level splitting versus voltage phase diagram shows regions of stable self-sustained current oscillations immersed in a region of stable stationary states. Transitions between stationary states and self-sustained current oscillations are systematically analyzed by both voltage and level splitting abrupt switching. Sudden voltage or/and magnetic field changes may switch on current oscillations from an initial stationary state, and reciprocally, current oscillations may disappear after sudden changes of voltage or/and magnetic field changes into the stable stationary states region. The results show how to design such a device to operate as a spin injector and a spin oscillator by tuning the Zeeman splitting (through the applied external magnetic field), the applied voltage and the sample configuration parameters (doping density, barrier and well widths, etc.) to select the desired stationary or oscillatory behavior. Phase diagram of Zeeman level splitting {delta} vs. dimensionless applied voltage {phi} for N = 10 QWs. White region: stable stationary states; black: stable self-sustained current oscillations. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  4. Operation of the enhanced ATLAS First Level Calorimeter Trigger at the start of Run-2

    CERN Document Server

    Palka, Marek; The ATLAS collaboration

    2015-01-01

    In 2015 the LHC will operate with a higher center-of-mass energy and proton beams luminosity. To keep a high trigger efficiency against an increased event rate, part of ATLAS Level-1 Calorimeter Trigger electronics have been re-designed or newly introduced (Pre-Processors, Merging Modules and Topological Processors). Additionally, to achieve the best possible resolution for the reconstructed physics objects, complex calibration and monitoring systems are employed. Hit rates and energy spectra down to channel level, based on reconstructed events, are supervised with the calorimeter trigger hardware. The performance of the upgraded Level-1 Calorimeter Trigger at the beginning of LHC Run-2 is illustrated.

  5. Experimental investigation of an optimum configuration for a high-voltage photoemission gun for operation at ≥500 kV

    Science.gov (United States)

    Nishimori, Nobuyuki; Nagai, Ryoji; Matsuba, Shunya; Hajima, Ryoichi; Yamamoto, Masahiro; Honda, Yosuke; Miyajima, Tsukasa; Iijima, Hokuto; Kuriki, Masao; Kuwahara, Makoto

    2014-05-01

    We demonstrated the generation of a 500-keV electron beam from a high dc voltage photoemission gun for an energy recovery linac light source [N. Nishimori et al., Appl. Phys. Lett. 102, 234103 (2013)]. This demonstration was achieved by addressing two discharge problems that lead to vacuum breakdown in the dc gun. One is field emission generated from a central stem electrode. We employed a segmented insulator to protect the ceramic insulator surface from the field emission. The other is microdischarge at an anode electrode or a vacuum chamber, which is triggered by microparticle transfer or field emission from a cathode electrode. An experimental investigation revealed that a larger acceleration gap, optimized mainly to reduce the surface electric field of the anode electrode, suppresses the microdischarge events that accompany gas desorption. It was also found that nonevaporable getter pumps placed around the acceleration gap greatly help to suppress those microdischarge events. The applied voltage as a function of the total gas desorption is shown to be a good measure for finding the optimum dc gun configuration.

  6. Coup d’Oeil: Military Geography and the Operational Level of War

    Science.gov (United States)

    1991-05-16

    templates becI-e the tool by which the omander and staff co-ktuct a warg•ming process to evaluate possible friendly ourse of action. 7he wargafing process...1747. trans. Brig Gen. Thomas R. Phillips. Roots of Strategy vol 1. (Harrisburg, PA., Stackpole Books, 1985), p. 338. 5. David G. Chandler, ne’ Capigns...Washington, D.C., GFO, 1990), p. 6. 12. David Jablonsky, "Strategy and the Operational Level of War." The Operational Art of Warfare Across the

  7. Developing operating procedures for a low-level radioactive waste disposal facility

    Energy Technology Data Exchange (ETDEWEB)

    Sutherland, A.A.; Miner, G.L.; Grahn, K.F.; Pollard, C.G. [Rogers and Associates Engineering Corp., Salt Lake City, UT (United States)

    1993-10-01

    This document is intended to assist persons who are developing operating and emergency procedures for a low-level radioactive waste disposal facility. It provides 25 procedures that are considered to be relatively independent of the characteristics of a disposal facility site, the facility design, and operations at the facility. These generic procedures should form a good starting point for final procedures on their subjects for the disposal facility. In addition, this document provides 55 annotated outlines of other procedures that are common to disposal facilities. The annotated outlines are meant as checklists to assist the developer of new procedures.

  8. Preparing to be Deceived: Counterdeception at the Operational Level of War,

    Science.gov (United States)

    1988-05-08

    Iec r, (;1( U I’ Ph11i, J4 )ro1e s, Ph.D) Degre-e Prog rams Accepted th is _____ day of 1988. Accessionl For ?4TIS GRAMt DTIC TAB Ullannoujiced Q...OPERATIONAL LEVEL OF WAR by Michael B. Weimer, USA, 59 pages. This study examirts counterdeception capabilities,,/ in U.S. Army operational forces. Th - c...bridges were being built across the Rhein between 11 +’! [ " e ’ ’ ’’ , ’ - - ,, , "A > Bonn and Bingen and Germans were known to be making efforts to

  9. 电网电压不平衡时三电平整流器静止坐标系控制研究%Control of Three-Level Rectifier in Stationary Coordinate System Under Unbalanced Grid Voltage

    Institute of Scientific and Technical Information of China (English)

    宋文祥; 董英; 阮智勇

    2013-01-01

    电网电压不平衡时,传统的整流器控制方法性能良好,但计算和控制复杂.和传统方法相比,文章采用的方法不需要对电网电压进行旋转变换和相位检测,也不必提取控制变量的正负序分量,从而有效降低了系统计算的复杂性和延迟.通过分析静止坐标系下的三电平整流器瞬时功率,在保证直流侧电压稳定及交流侧单位功率因数的条件下算得电流指令值.针对该控制方法,在Matlab/simulink 数字仿真环境下对其进行了离散化仿真,实现了电网电压单相跌落或者有谐波时,直流母线电压基本稳定及交流侧电压电流同相位.%Traditional rectifier controlling methods possess good performance under unbalanced network voltage, however their computation and control are complex. A control method of three-level rectifier in stationary coordinate system under unbalanced grid voltage is proposed, and comparing with traditional control methods it neither needs for the proposed method to perform rotating transformation and phase detection of grid voltage, nor to extract positive- and negative-sequence components, thus the time-delay and calculation complexity are effectively reduced. By means of analyzing instant power of three-level rectifier in stationary coordinate system, the reference current is calculated to ensure stable DC bus voltage and unit power factor at AC side. The proposed control method is simulated by Matlab /Simulink, and simulation results show that using the proposed control method the voltage of DC bus is basically stable and the current and voltage at AC side are in-phase while single-phase voltage sag occurs or harmonics exist in grid voltage.

  10. Noise levels of a track-laying tractor during field operations in the vineyard

    Directory of Open Access Journals (Sweden)

    Pietro Catania

    2013-09-01

    Full Text Available Noise in agriculture is one of the risk factors to be taken into account in the assessment of the health and safety of workers; in particular, it is known that the tractor is a source of high noise. The Italian Low Decree 81/2008 defined the requirements for assessing and managing noise risk identifying a number of procedures to be adopted at different noise levels to limit workers exposure. This paper concerns the analysis of the noise risk arising from the use of a tracklaying tractor during field operations carried out in the vineyard. The objective of this study was to evaluate the noise level that comes close to the ear of the operator driving the tractor measuring the values of equivalent sound level (Leq(A and peak sound pressure (LCpk. We considered four options related to the same tractor coupled with the following tools to perform some farming operations: rototilling, chisel plough, flail mowers and vibro farmer. We considered three test conditions: T1 in flat (slope 0%, T2 uphill and T3 downhill (both 30% slope. The instrument used for the measurements is a precision integrating portable sound level meter, class 1, model HD2110L by Delta OHM, Italy. Each survey lasted 2 minutes, with an interval of measurement equal to 0.5 s. The tests were performed in compliance with the standards ISO 9612 and ISO 9432. The results show that the measured sound levels exceed the limits allowed by the regulations in almost all the test conditions; values exceeding the threshold limit of 80 dB(A were recorded coming up to a maximum value of 92.8 dB(A for flail mowers in test T1. When limits imposed by the regulations are exceeded, the operator is obliged to wear the appropriate Personal Protective Equipment.

  11. A Transformerless Medium Voltage Multiphase Motor Drive System

    Directory of Open Access Journals (Sweden)

    Dan Wang

    2016-04-01

    Full Text Available A multiphase motor has several major advantages, such as high reliability, fault tolerance, and high power density. It is a critical issue to develop a reliable and efficient multiphase motor drive system. In this paper, a transformerless voltage source converter-based drive system for a medium-voltage (MV multiphase motor is proposed. This drive converter employs cascaded H-bridge rectifiers loaded by H-bridge inverters as the interface between the grid and multiphase motor. The cascaded H-bridge rectifier technique makes the drive system able to be directly connected to the MV grid without the phase-shifting transformer because it can offset the voltage level gap between the MV grid and the semiconductor devices, provide near-sinusoidal AC terminal voltages without filters, and draw sinusoidal line current from the grid. Based on a digital signal processor (DSP, a complete improved Phase Disposition Pulse Width Modulation (PD-PWM method is developed to ensure the individual DC-link capacitor voltage balancing for enhancing the controllability and limiting the voltage and power stress on the H-bridge cells. A downscaled prototype is designed and developed based on a nine-phase motor. The experimental results verify the excellent performances of the proposed drive system and control strategy in steady-state and variant-frequency startup operations.

  12. Voltage-Controlled Floating Resistor Using DDCC

    Directory of Open Access Journals (Sweden)

    M. Kumngern

    2011-04-01

    Full Text Available This paper presents a new simple configuration to realize the voltage-controlled floating resistor, which is suitable for integrated circuit implementation. The proposed resistor is composed of three main components: MOS transistor operating in the non-saturation region, DDCC, and MOS voltage divider. The MOS transistor operating in the non-saturation region is used to configure a floating linear resistor. The DDCC and the MOS transistor voltage divider are used for canceling the nonlinear component term of MOS transistor in the non-saturation region to obtain a linear current/voltage relationship. The DDCC is employed to provide a simple summer of the circuit. This circuit offers an ease for realizing the voltage divider circuit and the temperature effect that includes in term of threshold voltage can be compensated. The proposed configuration employs only 16 MOS transistors. The performances of the proposed circuit are simulated with PSPICE to confirm the presented theory.

  13. Operating experience during high-level waste vitrification at the West Valley Demonstration Project

    Energy Technology Data Exchange (ETDEWEB)

    Valenti, P.J.; Elliott, D.I.

    1999-01-01

    This report provides a summary of operational experiences, component and system performance, and lessons learned associated with the operation of the Vitrification Facility (VF) at the West Valley Demonstration Project (WVDP). The VF was designed to convert stored high-level radioactive waste (HLW) into a stable waste form (borosilicate glass) suitable for disposal in a federal repository. Following successful completion on nonradioactive test, HLW processing began in July 1995. Completion of Phase 1 of HLW processing was reached on 10 June 1998 and represented the processing of 9.32 million curies of cesium-137 (Cs-137) and strontium-90 (Sr-90) to fill 211 canisters with over 436,000 kilograms of glass. With approximately 85% of the total estimated curie content removed from underground waste storage tanks during Phase 1, subsequent operations will focus on removal of tank heel wastes.

  14. High-Level Functional and Operational Requirements for the Advanced Fuel Cycle Facilty

    Energy Technology Data Exchange (ETDEWEB)

    Charles Park

    2006-12-01

    High-Level Functional & Operational Requirements for the AFCF -This document describes the principal functional and operational requirements for the proposed Advanced Fuel Cycle Facility (AFCF). The AFCF is intended to be the world's foremost facility for nuclear fuel cycle research, technology development, and demonstration. The facility will also support the near-term mission to develop and demonstrate technology in support of fuel cycle needs identified by industry, and the long-term mission to retain and retain U.S. leadership in fuel cycle operations. The AFCF is essential to demonstrate a more proliferation-resistant fuel cycle and make long-term improvements in fuel cycle effectiveness, performance and economy.

  15. Optimal Work Area Selection of Stand-alone Photovoltaic Generation System Under Constant-Voltage Operation Mode%独立光伏系统恒压工作模式下最优工作区的选择

    Institute of Scientific and Technical Information of China (English)

    侯世英; 殷忠宁; 薛原; 曾鹏

    2012-01-01

    独立光伏系统中,当光伏电池输出的电能超出蓄电池和负载所需时,系统会过渡到一种非常重要的工作模式,即恒压工作模式。恒压模式下,对应同一负载,光伏电池存在2个工作点,分别位于最大功率点的左侧和右侧,即光伏电池i-u特性曲线的电流源区和电压源区。对这2个不同工作区域内光伏系统的稳定性进行了分析,提出了相应的控制方式。首先对光伏电池进行线性化处理,推导出光伏电池的线性化等效模型,并建立了整个系统的数学建模,在频率域内对不同工作点处系统的稳定性进行了分析。结果表明,恒压工作模式下,独立光伏系统工作于光伏电池的电压源区时,具有更好的稳定性。搭建的仿真模型在时域内验证了上述分析结果的正确性。%In stand-alone photovoltaic (PV) generation system, when the electric energy output from PV cells exceeds the power demand of batteries and loads, the usual operation mode of PV generation system will be turned into a very important operation mode, i.e., the constant voltage mode. Under constant voltage operation mode of PV array, there are two working points for the same load, which locate at the left side and right side of the maximum power point of the PV array, i.e., the current source region and voltage source region of current-voltage characteristics of PV array. The stability of PV system in the two different working regions is analyzed and corresponding control strategies are proposed. Firstly, the linearization of PV array is performed to derive the linearized equivalent model and to build the mathematical model of the whole system, then the stability of PV system at different working points is analyzed in the frequency domain. Analysis results show that under constant voltage operation mode, when stand-alone PV generation system works in the voltage source region of PV array the system is more stable

  16. Flicker Caused by Operation of Industrial Technology

    Directory of Open Access Journals (Sweden)

    Martin Kaspirek

    2016-01-01

    Full Text Available There are more and more electrical devices operating in industrial plants which impact negatively on the distribution network. The EN 50160 standard defines the voltage characteristics of electricity supplied by the public distribution system and it is a problem for a distribution network operator when the voltage quality in the distribution network does not comply with the requirements of the EN 50160 standard because of complaints about voltage quality. Such a complaint is justified and the distribution network operator has to pay a penalty and has to remedy the situation. This paper describes a problem of flicker in the medium-voltage distribution grid when the flicker is produced by one customer operating a forging press. The remedies from the side of the distribution network operator and the customer with the aim of reducing the flicker level in the grid are described.

  17. Congestion management considering voltage security of power systems

    Energy Technology Data Exchange (ETDEWEB)

    Esmaili, Masoud; Shayanfar, Heidar Ali [Centre of Excellence for Power System Automation and Operation, Iran Univ. of Science and Technology, Tehran (Iran); Amjady, Nima [Dept. of Electrical Engineering, Semnan Univ., Semnan (Iran)

    2009-10-15

    Congestion in a power network is turned up due to system operating limits. To relieve congestion in a deregulated power market, the system operator pays to market participants, GENCOs and DISCOs, to alter their active powers considering their bids. After performing congestion management, the network may be operated with a low security level because of hitting some flows their upper limit and some voltages their lower limit. In this paper, a novel congestion management method based on the voltage stability margin sensitivities is introduced. Using the proposed method, the system operator so alleviates the congestion that the network can more retain its security. The proposed method not only makes the system more secure after congestion management than other methods already presented for this purpose but also its cost of providing security is lower than the earlier methods. Test results of the proposed method along with the earlier ones on the New-England test system elaborate the efficiency of the proposed method from the viewpoint of providing a better voltage stability margin and voltage profile as well as a lower security cost. (author)

  18. Thermal Analysis of Multi-MW Two-Level Generator Side Converters with Reduced Common-Mode-Voltage Modulation Methods for Wind Turbines

    DEFF Research Database (Denmark)

    Qin, Zian; Liserre, Marco; Blaabjerg, Frede

    2013-01-01

    Thermal performance is one of the main indicators of power converter, since it is related to both the cost of cooling system and the reliability of the power converter. Moreover, the common-mode voltage in motor driver may damage the bearing of the motor and also cause failure. Therefore, both...

  19. 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...

  20. 风电集中并网运行对系统电压稳定性的影响研究%Study on System Impacts of Voltage Stability about Wind Power Concentrated Grid-Connected Operation

    Institute of Scientific and Technical Information of China (English)

    付小伟; 王进; 郭伟; 郑剑武

    2012-01-01

    Uncertainty of wind power resources and operating characteristics of the wind turbine itself makes wind turbine output power of change, which is equivalent to big power system disturbances. With the gradual increase of wind power penetration, it's high time to study the Voltage stability of large grid-connected wind power operation problem, it detail analyses the effect of voltage stability about wind farm under different wind speed model, installed capacity of wind power and fault clearing time. The static synchronous compensator applied to wind farms, according to the simulation results, the voltage restore rapidly after the faults cleared, so the low voltage ride through(LVRT)capability of wind turbines is improved, ensures the continuous operation of wind turbines and the security of the power network%风力资源的不确定性和风电机组本身的运行特性使风电机组的输出功率随之变化,对电力系统来说相当于一个大的扰动。随着风电穿透功率的逐步增加,大规模风电并网运行的电压稳定性问题亟待研究。利用Matlab/Simulink建立风电场仿真模型,详细分析了不同风速模型、风电场装机容量及短路故障切除时间下风电场对电压稳定性的影响。把静止同步补偿器(StaticSynchronousCompensator,STATCOM)应用到风电场中,仿真结果表明,STATCOM可以改善风电场的电压稳定性,提高了风电机组的低电压穿越能力,确保风电机组连续运行及电网安全稳定。

  1. Architecture, Voltage, and Components for a Turboelectric Distributed Propulsion Electric Grid

    Science.gov (United States)

    Armstrong, Michael J.; Blackwelder, Mark; Bollman, Andrew; Ross, Christine; Campbell, Angela; Jones, Catherine; Norman, Patrick

    2015-01-01

    The development of a wholly superconducting turboelectric distributed propulsion system presents unique opportunities for the aerospace industry. However, this transition from normally conducting systems to superconducting systems significantly increases the equipment complexity necessary to manage the electrical power systems. Due to the low technology readiness level (TRL) nature of all components and systems, current Turboelectric Distributed Propulsion (TeDP) technology developments are driven by an ambiguous set of system-level electrical integration standards for an airborne microgrid system (Figure 1). While multiple decades' worth of advancements are still required for concept realization, current system-level studies are necessary to focus the technology development, target specific technological shortcomings, and enable accurate prediction of concept feasibility and viability. An understanding of the performance sensitivity to operating voltages and an early definition of advantageous voltage regulation standards for unconventional airborne microgrids will allow for more accurate targeting of technology development. Propulsive power-rated microgrid systems necessitate the introduction of new aircraft distribution system voltage standards. All protection, distribution, control, power conversion, generation, and cryocooling equipment are affected by voltage regulation standards. Information on the desired operating voltage and voltage regulation is required to determine nominal and maximum currents for sizing distribution and fault isolation equipment, developing machine topologies and machine controls, and the physical attributes of all component shielding and insulation. Voltage impacts many components and system performance.

  2. Relationship between container ship underwater noise levels and ship design, operational and oceanographic conditions

    Science.gov (United States)

    McKenna, Megan F.; Wiggins, Sean M.; Hildebrand, John A.

    2013-05-01

    Low-frequency ocean ambient noise is dominated by noise from commercial ships, yet understanding how individual ships contribute deserves further investigation. This study develops and evaluates statistical models of container ship noise in relation to design characteristics, operational conditions, and oceanographic settings. Five-hundred ship passages and nineteen covariates were used to build generalized additive models. Opportunistic acoustic measurements of ships transiting offshore California were collected using seafloor acoustic recorders. A 5-10 dB range in broadband source level was found for ships depending on the transit conditions. For a ship recorded multiple times traveling at different speeds, cumulative noise was lowest at 8 knots, 65% reduction in operational speed. Models with highest predictive power, in order of selection, included ship speed, size, and time of year. Uncertainty in source depth and propagation affected model fit. These results provide insight on the conditions that produce higher levels of underwater noise from container ships.

  3. A quantitative Kirkpatrick Level 1 and 2 study of equipment specialist apprentice operations training

    Science.gov (United States)

    Hughes, Dirk D.

    The primary purpose of the quantitative experimental study is to compare employee-learning outcomes for a course of study that is offered in two formats: explicit and tacit instructor led and explicit e-learning operations training. A Kirkpatrick Level 2 course examination is used to establish a pretest knowledge baseline and to measure posttest learning outcomes for each instructional format. A secondary purpose is to compare responses of the two groups using a Kirkpatrick Level 1 customer satisfaction index survey. Several authors reported the United States electric utility industry would have an employee attrition issue during the 2010 through 2015 period. This is at the same time the industry will be experiencing an increased demand for electricity. There now is a demand for highly training powerplant operators. A review of literature yielded few studies comparing instructor led training and e-based training. Though the Electric Power Research Institute stated the two training modes would be acceptable instruction, the organization did not develop a quantifiable justified recommendation as to the training. Subjects participated in a basic operations course and decided to take either the instructor led or e-based training course. Results of the study concluded that both instructor led and e-based training provided significant learning to the participants. The Kirkpatrick Level 1 results indicated significantly better results for instructor led training. There was not a significant difference in the Kirkpatrick Level 2 results between the two training modalities. Recommendation for future research include conducting a quantitative studies including a Phillips Level 5 study and qualitative studies including a more detailed examination of the customer satisfaction survey (Kirkpatrick Level 1).

  4. A Low-Voltage Electronically Tunable MOSFET-C Voltage-Mode First-Order All-Pass Filter Design

    Directory of Open Access Journals (Sweden)

    B. Metin

    2013-12-01

    Full Text Available This paper presents a simple electronically tunable voltage-mode first-order all-pass filter realization with MOSFET-C technique. In comparison to the classical MOSFET-C filter circuits that employ active elements including large number of transistors the proposed circuit is only composed of a single two n-channel MOSFET-based inverting voltage buffer, three passive components, and one NMOS-based voltage-controlled resistor, which is with advantage used to electronically control the pole frequency of the filter in range 103 kHz to 18.3 MHz. The proposed filter is also very suitable for low-voltage operation, since between its supply rails it uses only two MOSFETs. In the paper the effect of load is investigated. In addition, in order to suppress the effect of non-zero output resistance of the inverting voltage buffer, two compensation techniques are also introduced. The theoretical results are verified by SPICE simulations using PTM 90 nm level-7 CMOS process BSIM3v3 parameters, where +/- 0.45 V supply voltages are used. Moreover, the behavior of the proposed filter was also experimentally measured using readily available array transistors CD4007UB by Texas Instruments.

  5. Investigation of pulsed voltage limiters characteristics

    Directory of Open Access Journals (Sweden)

    Karimov A. V.

    2012-06-01

    Full Text Available A new method for measuring the voltage limit is offered. It has been designed to measure high-power pulsed current of voltage limiters. The error of this method is half as much as the error of the known method of direct measurement. The investigation of dependence of power capability of single-crystal and double-crystal voltage limiters and of the pulsed operation time on pulse duration.

  6. A System for Generating Operational Sketches Based on the Multi-level Graphic Library

    Institute of Scientific and Technical Information of China (English)

    BAO Zhen-qiang; WANG Ning-sheng

    2001-01-01

    This paper points out the limitations of both parametric and geometric model methodscommonly applied to generate operational sketches in CAPP. The ideas of multi-level graphic library areintroduced and a new generative method based on this library which combines parametric method withgeometric model method is presented. The principles and characteristics of the construction of the library aredescribed in detail and the feature data structure corresponding with the library is also presented.

  7. Prediction of Long-term Post-operative Testosterone Replacement Requirement Based on the Pre-operative Tumor Volume and Testosterone Level in Pituitary Macroadenoma.

    Science.gov (United States)

    Lee, Cheng-Chi; Chen, Chung-Ming; Lee, Shih-Tseng; Wei, Kuo-Chen; Pai, Ping-Ching; Toh, Cheng-Hong; Chuang, Chi-Cheng

    2015-11-05

    Non-functioning pituitary macroadenomas (NFPAs) are the most prevalent pituitary macroadenomas. One common symptom of NFPA is hypogonadism, which may require long-term hormone replacement. This study was designed to clarify the association between the pre-operative tumor volume, pre-operative testosterone level, intraoperative resection status and the need of long-term post-operative testosterone replacement. Between 2004 and 2012, 45 male patients with NFPAs were enrolled in this prospective study. All patients underwent transsphenoidal surgery. Hypogonadism was defined as total serum testosterone levels of testosterone to patients with defined hypogonadism or clinical symptoms of hypogonadism. Hormone replacement for longer than 1 year was considered as long-term therapy. The need for long-term post-operative testosterone replacement was significantly associated with larger pre-operative tumor volume (p = 0.0067), and lower pre-operative testosterone level (p = 0.0101). There was no significant difference between the gross total tumor resection and subtotal resection groups (p = 0.1059). The pre-operative tumor volume and testosterone level impact post-operative hypogonadism. By measuring the tumor volume and the testosterone level and by performing adequate tumor resection, surgeons will be able to predict post-operative hypogonadism and the need for long-term hormone replacement.

  8. Multi-level SLIC superpixels segmentation method based on edge detection operator

    Science.gov (United States)

    Ni, Sen; Fu, Dongmei; Yang, Tao

    2016-10-01

    Simple linear iterative clustering (SLIC) super-pixel algorithm for its excellent performance and efficient border holding computational efficiency is widely used in image processing. But with the increase of the number of super-pixels, there will be a lot of redundancy in the image merging process. In this paper, we propose a multi-level super-pixels method based SLIC algorithm, which focuses on the target area to set up edge detection operator for generating multi-level super-pixels. Simulation results show that the proposed method ensures the accuracy of extraction and improves the computational efficiency.

  9. Design, construction and operational results of the IGBT controlled solid state modulator high voltage power supply used in the high power RF systems of the Low Energy Demonstration Accelerator of the accelerator production of tritium (APT) project

    Energy Technology Data Exchange (ETDEWEB)

    Bradley, J.T. III; Rees, D.; Przeklasa, R.S. [Los Alamos National Lab., NM (United States); Scott, M.C. [Continental Electronics Corp., Dallas, TX (United States)

    1998-12-31

    The 1700 MeV, 100 mA Accelerator Production of Tritium (APT) Proton Linac will require 244 1 MW, continuous wave RF systems. 1 MW continuous wave klystrons are used as the RF source and each klystron requires 95 kV, 17 A of beam voltage and current. The cost of the DC power supplies is the single largest percentage of the total RF system cost. Power supply reliability is crucial to overall RF system availability and AC to DC conversion efficiency affects the operating cost. The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory (LANL) will serve as the prototype and test bed for APT. The design of the RF systems used in LEDA is driven by the need to field test high efficiency systems with extremely high reliability before APT is built. The authors present a detailed description and test results of one type of advanced high voltage power supply system using Insulated Gate Bipolar Transistors (IGBTs) that has been used with the LEDA High Power RF systems. The authors also present some of the distinctive features offered by this power supply topology, including crowbarless tube protection and modular construction which allows graceful degradation of power supply operation.

  10. A New Zero Voltage Switching Buck-Boost Type DC-DC Converter

    Directory of Open Access Journals (Sweden)

    Majid Delshad

    2010-03-01

    Full Text Available In this paper, a new zero voltage switching isolated buck-boost DC-DC converter with active clamp circuit is proposed. The active clamp circuit in this converter not only absorbs voltage spikes across the main switch but also provides soft switching conditions for all switches. All switches are PWM controlled which simplifies the control implementation. One of the main advantages of this converter is the that it operating can operate at high power levels while soft switching conditions exist in both buck and boost modes of converter operation. Since this converter can operate over a wide input voltage range, it can be employed in power factor correction. The experimental results obtained from a 150W prototype circuit operating at 100KHz are presented to confirm the integrity of the proposed circuit.

  11. Automated Voltage Control in LHCb

    CERN Document Server

    Granado Cardoso, L; Jacobsson, R

    2011-01-01

    LHCb is one of the 4 LHC experiments. In order to ensure the safety of the detector and to maximize efficiency, LHCb needs to coordinate its own operations, in particular the voltage configuration of the different subdetectors, according to the accelerator status. A control software has been developed for this purpose, based on the Finite State Machine toolkit and the SCADA system used for control throughout LHCb (and the other LHC experiments). This software permits to efficiently drive both the Low Voltage (LV) and High Voltage (HV) systems of the 10 different sub-detectors that constitute LHCb, setting each sub-system to the required voltage (easily configurable at run-time) based on the accelerator state. The control software is also responsible for monitoring the state of the Sub-detector voltages and adding it to the event data in the form of status-bits. Safe and yet flexible operation of the LHCb detector has been obtained and automatic actions, triggered by the state changes of the ...

  12. Characterisation of the VELO High Voltage System

    CERN Document Server

    Rakotomiaramanana, B; Eklund, L

    2008-01-01

    The high voltage system supplies the bias voltage to the 88 silicon sensors which comprise the LHCb Vertex Locator (VELO). This note describes the results of the tests which have been performed on the hardware of the high voltage system of the VELO. Each individual test detailed in this note corresponds to a specific requirement of the system. These requirements arise primarily from ensuring the safety of the silicon sensors and the quality of the data taken from the VELO modules. The tests performed are in four categories: normal operation of the high voltage system; vercation of its stability under operation; discussion of its behaviour in failure modes; and details of operation at low voltage. Noteworthy issues, identified through the tests, include the behaviour of the high voltage modules at voltages below 9V, the current limit that can be applied during ramping of the voltage, and the speed with which the voltage is cut during failures of the system. The results of these tests provide high confidence th...

  13. Characterisation of the VELO High Voltage System

    CERN Document Server

    Rakotomiaramanana, B; Parkes, C; Eklund, L

    2008-01-01

    The high voltage system supplies the bias voltage to the 88 silicon sensors which comprise the LHCb Vertex Locator (VELO). This note describes the results of the tests which have been performed on the hardware of the high voltage system of the VELO. Each individual test detailed in this note corresponds to a specific requirement of the system. These requirements arise primarily from ensuring the safety of the silicon sensors and the quality of the data taken from the VELO modules. The tests performed are in four categories: normal operation of the high voltage system; verification of its stability under operation; discussion of its behaviour in failure modes; and details of operation at low voltage. Noteworthy issues, identified through the tests, include the behaviour of the high voltage modules at voltages below 9V, the current limit that can be applied during ramping of the voltage, and the speed with which the voltage is cut during failures of the system. The results of these tests provide high confidence...

  14. 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....

  15. Corporate marketing potential assessment model in the context of operational, tactical and strategic levels

    Directory of Open Access Journals (Sweden)

    L.V. Potrashkova

    2013-12-01

    Full Text Available The aim of the article. The aim of this research is to develope the mathematic model structure of result-oriented evaluation of corporate marketing potential in the context of management potential levels (operational, tactical and strategic that takes into account multiple possible uses of marketing resources and various options for the development of corporate environment. The results of the analysis. The new scientific result of this research is represented by the developed structure of the system of analytical mathematic models for assessing marketing potential of the company in the context of its management levelsoperational, tactical and strategic. According to the proposed system of models every level of marketing potential (operational, tactical and strategic is described through a set of possible enterprise production sales volumes for different states of the environment parameters and the parameters of a certain level of marketing resources management at corresponding period of time (short, medium and long term. The proposed system of models has the following clue characteristics: marketing potential assessment is based on the result-oriented approach. It characterizes enterprise capability for creating demand for its products in different conditions of corporate environment and for different variants of managerial decisions concerning different parameters of production promotion and distribution (e.g. for different pricing options; different variants of corporate investment and innovations program; marketing potential assessment is implemented in the context of management levels of the potential – operational, tactical and strategic – so, it reflects operational, tactical and strategic capabilities of the company concerning production promotion and distribution; the models for assessing different levels of potential (operational, tactical and strategic differ in such of ways: by specification of the resources` characteristics

  16. Nitrous Oxide Levels In Operating and Recovery Rooms of Iranian Hospitals

    Directory of Open Access Journals (Sweden)

    Sh Sadigh Maroufi

    2011-06-01

    Full Text Available "nBackground: Nitrous oxide (N2O is the oldest anesthetic in routine clinical use and its occupational exposure is under regulation by many countries. As studies are lacking to demonstrate the status of nitrous oxide levels in operating and recovery rooms of Iranian hospitals, we aimed to study its level in teaching hospitals of Tehran University of Medical Sciences."nMethods: During a 6-month period, we have measured the shift-long time weighted average concentration of N2O in 43 op­erating and 12 recovery rooms of teaching hospitals of Tehran University of Medical Sciences."nResults: The results show that the level of nitrous oxide in all hospitals is higher than the limits set by different countries and anesthetists are at higher risk of exposure. In addition, it was shown that installation of air ventilation could reduce not only the overall exposure level, but also the level of exposure of anesthetists in comparison with other personnel."nConclusion: The high nitrous oxide level in Iranian hospitals necessitates improvement of waste gas evacuation systems and regular monitoring to bring the concentration of this gas into the safe level.

  17. 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.

  18. Evaluation of the Voltage Support Strategies for the Low Voltage Grid Connected PV

    DEFF Research Database (Denmark)

    Demirok, Erhan; Sera, Dezso; Teodorescu, Remus

    2010-01-01

    PVs. In order to increase PV penetration level further, new voltage support control functions for individual inverters are required. This paper investigates distributed reactive power regulation and active power curtailment strategies regarding the development of PV connection capacity by evaluation......Admissible range of grid voltage is one of the strictest constraints for the penetration of distributed photovoltaic (PV) generators especially connection to low voltage (LV) public networks. Voltage limits are usually fulfilled either by network reinforcements or limiting of power injections from...

  19. Operating Room Efficiency: Benefits of an Orthopaedic Traumatologist at a Level II Trauma Center.

    Science.gov (United States)

    Althausen, Peter L; Kauk, Justin R; Shannon, Steven; Lu, Minggen; O'Mara, Timothy J; Bray, Timothy J

    2016-12-01

    Fellowship-trained orthopaedic traumatologists are presumably taught skill sets leading to "best practice" outcomes and more efficient use of hospital resources. This should result in more favorable economic opportunities when compared with general orthopaedic surgeons (GOSs) providing similar clinical services. The purpose of our study was to compare the operating room utilization and financial data of traumatologists versus GOSs at a level II trauma center. Retrospective review. Level II community-based trauma hospital. Patients who presented to the emergency room at our institution with fractures and orthopaedic conditions requiring surgical intervention from January 1, 2010, to December 31, 2011. Operative fracture fixation by members of our orthopaedic trauma panel, including fellowship and nontrauma fellowship-trained orthopaedic surgeons. Our institutional database was queried to determine operative times, surgical supply and implant costs, and surgery labor expenses. Patients were stratified according to those treated by our trauma panel's 3 traumatologists and those treated by the 15 GOSs on our trauma panel. These 2 groups were then compared using standard statistical methods. A total of 6449 orthopedic cases were identified and 2076 of these involved fracture care. One thousand one hundred ninety-nine patients were treated by traumatologists and 877 by GOSs. There was no statistical difference detected in American Society of Anesthesiologists score between trauma and nontrauma groups. Overall, the traumatologist group demonstrated significantly decreased procedure times when compared with the GOS group (55.6 vs. 75.8 minutes, P , 0.0001). In 16 of 18 most common procedure types, traumatologists were more efficient. This led to significantly decreased surgical labor costs ($381.4 vs. $484.8; P Economic Level IV. See Instructions for Authors for a complete description of levels of evidence.

  20. Application of Fuzzy Logic Inference System, Interval Numbers and Mapping Operator for Determination of Risk Level

    Directory of Open Access Journals (Sweden)

    Mohsen Omidvar

    2015-12-01

    Full Text Available Background & objective: Due to the features such as intuitive graphical appearance, ease of perception and straightforward applicability, risk matrix has become as one of the most used risk assessment tools. On the other hand, features such as the lack of precision in the classification of risk index, as well as subjective computational process, has limited its use. In order to solve this problem, in the current study we used fuzzy logic inference systems and mathematical operators (interval numbers and mapping operator. Methods: In this study, first 10 risk scenarios in the excavation and piping process were selected, then the outcome of the risk assessment were studied using four types of matrix including traditional (ORM, displaced cells (RCM , extended (ERM and fuzzy (FRM risk matrixes. Results: The results showed that the use of FRM and ERM matrix have prority, due to the high level of " Risk Tie Density" (RTD and "Risk Level Density" (RLD in the ORM and RCM matrix, as well as more accurate results presented in FRM and ERM, in risk assessment. While, FRM matrix provides more reliable results due to the application of fuzzy membership functions. Conclusion: Using new mathematical issues such as fuzzy sets and arithmetic and mapping operators for risk assessment could improve the accuracy of risk matrix and increase the reliability of the risk assessment results, when the accurate data are not available, or its data are avaliable in a limit range.

  1. 隔离型DC/DC在高压电压电流源设计中的应用%Application of isolated DC/DC converter in high level voltage and current source design

    Institute of Scientific and Technical Information of China (English)

    黄弋; 周菁

    2012-01-01

    由于隔离型DC/DC的安全性、隔离性等特征,该类器件广泛应用于多个电子、工业领域,本文主要介绍了隔离型DC/DC在高压电压电流源中的应用。本文将隔离型双输出DC/DC引入设计,利用DC/DC的隔离特性,将电压电流源的次级输出作为DC/DC器件参考地,将DC/DC器件的两路输出电压作为相关运算放大器的电源电压。常规高压电压电流源设计中需要大量采用高压运算放大器,采用此方案可使用较少的高压运算放大器及更低的成本实现相同功能,同时降低高压电源对PCB电路板上信号的影响。通过实际测量,文中方案输出稳定、精度高,满足设计与使用要求。文中用功能图纸对此类应用进行了详细说明。%Because of the Characteristics of safety and reliability, isolated DC/DC converter is widely used in many fields, such as electronic field and industry field. This paper describes the application of isolated DC/DC converter in ATE voltage and current source designing. The voltage and current source circuit are mainly realized by Operational amplifiers. When isolated DC/DC converter is used in the design, we can use less Operational amplifiers and cost less to realize the same function. In the project, the two voltage outputs of isolated DC/DC converter are used as power supply of Operational amplifiers, and the secondary output of voltage and current source is used as reference ground. It is effective to reduce system noise of high voltage power supply and to make signal quality on PCB getting better. It was confirmed that the system we discussed in this paper meet the requirements of reliability and precision through the measurement result. The details of the schematic are also describes in the paper

  2. Research on voltage-balanced asymmetric multi-level inverter for motor's speed control%电压自平衡式不对称多电平逆变器对电机调速的研究

    Institute of Scientific and Technical Information of China (English)

    曹莹; 付光杰; 侯永强

    2011-01-01

    Nowadays, multi-level inverter technique is already widely used in the high-voltage and high-power field. Meanwhile the hybrid asymmetric 6-level inverter has been focused on for its simple construction and waveforms without 0 level. However, we all know that mid-point voltage control is one of the technical difficulties to high-voltage high-power multi-level inverter circuit. So a new single-phase hybrid asymmetric 6-level inverter is researched in this paper. In the inverter a 3-level Half-bridge unit and a Half-bridge unit are cascaded to form an inverter phase leg. This kind of construction can make the mid-point voltage balance without any other special circuit and complicated control methods. Meanwhile, 6-lever will be put out at the end of the circuit. The EPWM control method is proposed considering the construction of the inverter. The experiment on the voltage-balanced asymmetric 6-level inverter for motor' s speed control is carried out and the ideal output waveforms show the feasibility of the construction and the reasonableness of the EPWM method.%多电平逆变技术已广泛应用于高压大功率的场合.不对称6电平逆变器由于其结构简单且输出没有0电平而受到广泛的关注.而高压大功率多电平逆变电路的一个技术难点是中点电压的控制问题.该文提出了一种新型的单相不对称混合六电平逆变器拓扑结构.该结构是由两电平半桥单元和三电平半桥单元级联而成的,这种拓扑结构无需特殊的均压电路或复杂的电容均压控制就可以实现电压自平衡功能.在解决了中点电压均衡难的问题的同时可以输出六电平.针对这种拓扑结构采用了阶梯波EPWM控制方法.仿真和实验证明了该新型拓扑结构的可行性及控制方式选用的合理性.

  3. Prediction of Long-term Post-operative Testosterone Replacement Requirement Based on the Pre-operative Tumor Volume and Testosterone Level in Pituitary Macroadenoma

    OpenAIRE

    Cheng-Chi Lee; Chung-Ming Chen; Shih-Tseng Lee; Kuo-Chen Wei; Ping-Ching Pai; Cheng-Hong Toh; Chi-Cheng Chuang

    2015-01-01

    Non-functioning pituitary macroadenomas (NFPAs) are the most prevalent pituitary macroadenomas. One common symptom of NFPA is hypogonadism, which may require long-term hormone replacement. This study was designed to clarify the association between the pre-operative tumor volume, pre-operative testosterone level, intraoperative resection status and the need of long-term post-operative testosterone replacement. Between 2004 and 2012, 45 male patients with NFPAs were enrolled in this prospective...

  4. 2.3-MW Medium-Voltage, Three-Level Wind Energy Inverter Applying a Unique Bus Structure and 4.5-kV Si/SiC Hybrid Isolated Power Modules: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Erdman, W.; Keller, J.; Grider, D.; VanBrunt, E.

    2014-11-01

    A high-efficiency, 2.3-MW, medium-voltage, three-level inverter utilizing 4.5-kV Si/SiC (silicon carbide) hybrid modules for wind energy applications is discussed. The inverter addresses recent trends in siting the inverter within the base of multimegawatt turbine towers. A simplified split, three-layer laminated bus structure that maintains low parasitic inductances is introduced along with a low-voltage, high-current test method for determining these inductances. Feed-thru bushings, edge fill methods, and other design features of the laminated bus structure provide voltage isolation that is consistent with the 10.4-kV module isolation levels. Inverter efficiency improvement is a result of the (essential) elimination of the reverse recovery charge present in 4.5-kV Si PIN diodes, which can produce a significant reduction in diode turn-off losses as well as insulated-gate bipolar transistor (IGBT) turn-on losses. The hybrid modules are supplied in industry-standard 140 mm x 130 mm and 190 mm x 130 mm packages to demonstrate direct module substitution into existing inverter designs. A focus on laminated bus/capacitor-bank/module subassembly level switching performance is presented.

  5. Effect of Ca doping level on the laser-induced voltages in tilted La{sub 1-x}Ca{sub x}MnO{sub 3} (0.1 ≤ x ≤ 0.7) thin films

    Energy Technology Data Exchange (ETDEWEB)

    Ma, Ji; Zhang, Hui; Chen, Qingming; Liu, Xiang [Kunming University of Science and Technology, Faculty of Materials Science and Engineering, Kunming (China); Theingi, Mya [Kunming University of Science and Technology, Faculty of Materials Science and Engineering, Kunming (China); University of Yangon, Department of Chemistry, Yangon (Myanmar)

    2014-03-15

    Tilted La{sub 1-x}Ca{sub x}MnO{sub 3} (0.1 ≤ x ≤ 0.7) thin films have been grown on vicinal cut LaAlO{sub 3} (100) substrate by pulsed laser deposition. The laser-induced voltage effect was studied at room temperature with the KrF excimer laser using as the thermal source. The relationships between Ca doping level and voltage signal, response time and anisotropy Seebeck coefficient were established. The voltage signal and anisotropy Seebeck coefficient increase at first with increasing Ca doping level, reach a maximum at the same Ca content around x = 0.5, and then decrease. The respond time decreases with the Ca concentration increasing, and changes very little after x = 0.5. The figure of merit F{sub m} was also the largest at this doping level, indicating a potential good performance of the photodetector devices. The variation of intrinsic structural and transport anisotropy induced by the change of Ca concentration has been proposed to account for the different LIV effects observed in LCMO thin films. (orig.)

  6. Model training curriculum for Low-Level Radioactive Waste Disposal Facility Operations

    Energy Technology Data Exchange (ETDEWEB)

    Tyner, C.J.; Birk, S.M.

    1995-09-01

    This document is to assist in the development of the training programs required to be in place for the operating license for a low-level radioactive waste disposal facility. It consists of an introductory document and four additional appendixes of individual training program curricula. This information will provide the starting point for the more detailed facility-specific training programs that will be developed as the facility hires and trains new personnel and begins operation. This document is comprehensive and is intended as a guide for the development of a company- or facility-specific program. The individual licensee does not need to use this model training curriculum as written. Instead, this document can be used as a menu for the development, modification, or verification of customized training programs.

  7. Credit risk analysis at the level of an operative branch of the bank

    Directory of Open Access Journals (Sweden)

    Imola DRIGA

    2010-12-01

    Full Text Available Credit risk is most simply defined as the potential that a borrower/counter party will fail to meet its obligations in accordance with agreed terms. The goal of credit risk management is to maintain credit risk exposure within targeted limits so that the bank can maximize risk adjusted return. In such cases, the account of the customer inevitably becomes overdue, the granted loan turns into a non-performing credit and the lending bank registers a decline of its profit. In order to prevent such situations, commercial banks must take certain measures of reducing credit risk. In order to assess the exposure to credit risk, we can operate with a system of indicators based on information obtained from financial statements. The paper presents how the exposure to this type of risk can be evaluated at the level of an operative branch of the bank.

  8. Decentralized Voltage Control Coordination of On-Load Tap Changer Transformers, Distributed Generation Units and Flexible Loads

    DEFF Research Database (Denmark)

    Romani Dalmau, Aina; Martinez Perez, David; Diaz de Cerio Mendaza, Iker

    2015-01-01

    . Under low penetration levels, several voltage regulation elements have been efficiently employed up to now. However, under large distributed generation levels, the traditional techniques have to be coordinated with new upcoming solutions, such us demand response. In this paper a simple and decentralized......The increase of distributed generation is expected to generate instabilities, such as power imbalances or voltage deviations in the power system. At the distribution level, maintaining the bus voltages within the stipulated limits is one of the major challenges for the distribution system operator...... approach is introduced in order to coordinate the voltage control capability from different assets in medium voltage networks. In this sense, the on-load tap changer strategy of the primary substation and the power factor control of wind turbines and combined heat and power plants are combined...

  9. A matter of quantum voltages.

    Science.gov (United States)

    Sellner, Bernhard; Kathmann, Shawn M

    2014-11-14

    Voltages inside matter are relevant to crystallization, materials science, biology, catalysis, and aqueous chemistry. The variation of voltages in matter can be measured by experiment, however, modern supercomputers allow the calculation of accurate quantum voltages with spatial resolutions of bulk systems well beyond what can currently be measured provided a sufficient level of theory is employed. Of particular interest is the Mean Inner Potential (V(o))--the spatial average of these quantum voltages referenced to the vacuum. Here we establish a protocol to reliably evaluate V(o) from quantum calculations. Voltages are very sensitive to the distribution of electrons and provide metrics to understand interactions in condensed phases. In the present study, we find excellent agreement with measurements of V(o) for vitrified water and salt crystals and demonstrate the impact of covalent and ionic bonding as well as intermolecular/atomic interactions. Certain aspects in this regard are highlighted making use of simple model systems/approximations. Furthermore, we predict V(o) as well as the fluctuations of these voltages in aqueous NaCl electrolytes and characterize the changes in their behavior as the resolution increases below the size of atoms.

  10. Depth of interaction and bias voltage depenence of the spectral response in a pixellated CdTe detector operating in time-over-threshold mode subjected to monochromatic X-rays

    Science.gov (United States)

    Fröjdh, E.; Fröjdh, C.; Gimenez, E. N.; Maneuski, D.; Marchal, J.; Norlin, B.; O'Shea, V.; Stewart, G.; Wilhelm, H.; Modh Zain, R.; Thungström, G.

    2012-03-01

    High stopping power is one of the most important figures of merit for X-ray detectors. CdTe is a promising material but suffers from: material defects, non-ideal charge transport and long range X-ray fluorescence. Those factors reduce the image quality and deteriorate spectral information. In this project we used a monochromatic pencil beam collimated through a 20μm pinhole to measure the detector spectral response in dependance on the depth of interaction. The sensor was a 1mm thick CdTe detector with a pixel pitch of 110μm, bump bonded to a Timepix readout chip operating in Time-Over-Threshold mode. The measurements were carried out at the Extreme Conditions beamline I15 of the Diamond Light Source. The beam was entering the sensor at an angle of \\texttildelow20 degrees to the surface and then passed through \\texttildelow25 pixels before leaving through the bottom of the sensor. The photon energy was tuned to 77keV giving a variation in the beam intensity of about three orders of magnitude along the beam path. Spectra in Time-over-Threshold (ToT) mode were recorded showing each individual interaction. The bias voltage was varied between -30V and -300V to investigate how the electric field affected the spectral information. For this setup it is worth noticing the large impact of fluorescence. At -300V the photo peak and escape peak are of similar height. For high bias voltages the spectra remains clear throughout the whole depth but for lower voltages as -50V, only the bottom part of the sensor carries spectral information. This is an effect of the low hole mobility and the longer range the electrons have to travel in a low field.

  11. Intra-operative remifentanil might influence pain levels in the immediate post-operative period after major abdominal surgery

    DEFF Research Database (Denmark)

    Hansen, E G; Duedahl, T H; Rømsing, J;

    2005-01-01

    Remifentanil, a widely used analgesic agent in anaesthesia, has a rapid onset and short duration of action. In clinical settings, this requires an appropriate pain strategy to prevent unacceptable pain in the post-operative period. The aim of this study was to investigate whether remifentanil had...... any impact on post-operative pain and opioid consumption after major abdominal surgery.......Remifentanil, a widely used analgesic agent in anaesthesia, has a rapid onset and short duration of action. In clinical settings, this requires an appropriate pain strategy to prevent unacceptable pain in the post-operative period. The aim of this study was to investigate whether remifentanil had...

  12. The CMS High Level Trigger: Commissioning and First Operation with LHC Beams

    CERN Document Server

    Felcini, Marta

    2009-01-01

    The CMS experiment will collect data from the proton-proton collisions delivered by the Large Hadron Collider (LHC) at a centre-of-mass energy up to 14 TeV. The CMS trigger system is designed to cope with unprecedented luminosities and LHC bunch-crossing rates up to 40 MHz. The unique CMS trigger architecture only employs two trigger levels. The Level-1 trigger is implemented using custom electronics. The High Level Trigger is implemented on a large cluster of commercial processors, the Filter Farm. Trigger menus have been developed for detector calibration and for fulfilment of the CMS physics program, at start-up of LHC operations, as well as for operations with higher luminosities. A complete multipurpose trigger menu developed for an early instantaneous luminosity of 10^{32}cm{-2}s{-1} has been tested in the HLT system under realistic online running conditions. The required computing power needed to process with no dead time a maximum HLT input rate of 50 kHz, as expected at startup, has been measured, us...

  13. Reference design and operations for deep borehole disposal of high-level radioactive waste.

    Energy Technology Data Exchange (ETDEWEB)

    Herrick, Courtney Grant; Brady, Patrick Vane; Pye, Steven; Arnold, Bill Walter; Finger, John Travis; Bauer, Stephen J.

    2011-10-01

    A reference design and operational procedures for the disposal of high-level radioactive waste in deep boreholes have been developed and documented. The design and operations are feasible with currently available technology and meet existing safety and anticipated regulatory requirements. Objectives of the reference design include providing a baseline for more detailed technical analyses of system performance and serving as a basis for comparing design alternatives. Numerous factors suggest that deep borehole disposal of high-level radioactive waste is inherently safe. Several lines of evidence indicate that groundwater at depths of several kilometers in continental crystalline basement rocks has long residence times and low velocity. High salinity fluids have limited potential for vertical flow because of density stratification and prevent colloidal transport of radionuclides. Geochemically reducing conditions in the deep subsurface limit the solubility and enhance the retardation of key radionuclides. A non-technical advantage that the deep borehole concept may offer over a repository concept is that of facilitating incremental construction and loading at multiple perhaps regional locations. The disposal borehole would be drilled to a depth of 5,000 m using a telescoping design and would be logged and tested prior to waste emplacement. Waste canisters would be constructed of carbon steel, sealed by welds, and connected into canister strings with high-strength connections. Waste canister strings of about 200 m length would be emplaced in the lower 2,000 m of the fully cased borehole and be separated by bridge and cement plugs. Sealing of the upper part of the borehole would be done with a series of compacted bentonite seals, cement plugs, cement seals, cement plus crushed rock backfill, and bridge plugs. Elements of the reference design meet technical requirements defined in the study. Testing and operational safety assurance requirements are also defined. Overall

  14. Design and operation of 140 GHz gyrotron oscillators for power levels up to 1 MW CW

    Energy Technology Data Exchange (ETDEWEB)

    Jory, H.; Bier, R.; Craig, L.J.; Felch, K.; Ives, L.; Lopez, N.; Spang, S.

    1986-12-01

    Varian has designed and tested 140 GHz gyrotron oscillators that have generated output powers of 100 kW CW and 200 kW for 1 ms pulses. Upcoming tubes will be designed to operate at power levels of 200 kW CW and ultimately up to 1 MW CW. The important design considerations which are addressed in the higher power tubes include the design of the electron gun, interaction circuit, and output window. These issues will be discussed and the results of the earlier 140 GHz gyrotron work at Varian will be summarized.

  15. The ATLAS trigger high-level trigger commissioning and operation during early data taking

    CERN Document Server

    Goncalo, R

    2008-01-01

    The ATLAS experiment is one of the two general-purpose experiments due to start operation soon at the Large Hadron Collider (LHC). The LHC will collide protons at a centre of mass energy of 14~TeV, with a bunch-crossing rate of 40~MHz. The ATLAS three-level trigger will reduce this input rate to match the foreseen offline storage capability of 100-200~Hz. After the Level 1 trigger, which is implemented in custom hardware, the High-Level Trigger (HLT) further reduces the rate from up to 100~kHz to the offline storage rate while retaining the most interesting physics. The HLT is implemented in software running in commercially available computer farms and consists of Level 2 and Event Filter. To reduce the network data traffic and the processing time to manageable levels, the HLT uses seeded, step-wise reconstruction, aiming at the earliest possible rejection. Data produced during LHC commissioning will be vital for calibrating and aligning sub-detectors, as well as for testing the ATLAS trigger and setting up t...

  16. Higher-level fusion for military operations based on abductive inference: proof of principle

    Science.gov (United States)

    Pantaleev, Aleksandar V.; Josephson, John

    2006-04-01

    The ability of contemporary military commanders to estimate and understand complicated situations already suffers from information overload, and the situation can only grow worse. We describe a prototype application that uses abductive inferencing to fuse information from multiple sensors to evaluate the evidence for higher-level hypotheses that are close to the levels of abstraction needed for decision making (approximately JDL levels 2 and 3). Abductive inference (abduction, inference to the best explanation) is a pattern of reasoning that occurs naturally in diverse settings such as medical diagnosis, criminal investigations, scientific theory formation, and military intelligence analysis. Because abduction is part of common-sense reasoning, implementations of it can produce reasoning traces that are very human understandable. Automated abductive inferencing can be deployed to augment human reasoning, taking advantage of computation to process large amounts of information, and to bypass limits to human attention and short-term memory. We illustrate the workings of the prototype system by describing an example of its use for small-unit military operations in an urban setting. Knowledge was encoded as it might be captured prior to engagement from a standard military decision making process (MDMP) and analysis of commander's priority intelligence requirements (PIR). The system is able to reasonably estimate the evidence for higher-level hypotheses based on information from multiple sensors. Its inference processes can be examined closely to verify correctness. Decision makers can override conclusions at any level and changes will propagate appropriately.

  17. Low operation voltage of GaN-based LEDs with Al-doped ZnO upper contact directly on p-type GaN without insert layer

    Science.gov (United States)

    Chen, P. H.; Chen, Yu An; Chang, L. C.; Lai, W. C.; Kuo, Cheng Huang

    2015-07-01

    Al-doped ZnO (AZO) film was evaporated on double-side polished sapphire, p-GaN layers, n+-InGaN-GaN short-period superlattice (SPS) structures, and GaN-based light-emitting diodes (LEDs) by e-beam. The AZO film on the p-GaN layer after thermal annealing exhibited an extremely high transparency (98% at 450 nm) and a small specific contact resistance of 2.19 × 10-2 Ω cm2, which was almost the same as that of as-deposited AZO on n+-SPS structure. With 20 mA injection current, the forward voltages were 3.30 and 3.27 V, whereas the output powers were 4.32 and 4.07 mW for the LED with AZO on insert n+-SPS upper contact and the LED with AZO on p-GaN upper contact (without insert layer), respectively. The small specific contact resistance and low operation voltage of LED with AZO on p-GaN upper contact was achieved by rapid thermal annealing (RTA) process.

  18. 异步电动机在不对称电压下运行时的性能变化%Operation characteristics change of induction motor at asymmetrical voltage

    Institute of Scientific and Technical Information of China (English)

    胡浩

    2015-01-01

    分析了三相异步电动机在不对称三相电压下运行性能(电机定子电流、电磁转矩和效率)的变化情况,结果表明,三相异步电动机在不对称电压运行时,至少有一相电流超过额定电流,电机转矩减少和效率降低。总结了不对称电压对电动机危害的一些情况,给出了电机运行时对三相电压对称度的要求。%The change of three-phase induction motor’ operation characteristics is analyzed and calculated at asymmetrical three-phase voltage, including stator current, electromagnetic torque and efficiency etc. of the motor. The results show that, while at least one phase current is over the rated current, the motor’ torque reduction and its efficiency reduction will decrease. Circs of damaging motor at asymmetrical three-phase voltage are summarized.

  19. Pembuatan Service Level Requirement, Service Level Agreement dan Operational Level Agreement pada layanan help desk SAP berdasarkan kerangka kerja ITIL versi 2011 (Studi Kasus : Pupuk Indonesia Holding Company

    Directory of Open Access Journals (Sweden)

    Nur Shabrina Prameswari

    2017-01-01

    Full Text Available PT. Pupuk Indonesia Holding Company baru saja melakukan implementasi SAP pada tahun 2014. Dalam penerapannya, perusahaan merasa perlu membuat help desk SAP sebagai pusat penanganan masalah bagi perusahaan dan 7 anak perusahaannya yang kemudian dapat berfungsi juga sebagai knowledge base yang berguna apabila ada masalah yang berulang diwaktu selanjutnya. Untuk merancang layanan help desk yang baik, perlu didefinisikannya target layanan dalam sebuah kontrak perjanjian antara pengguna layanan dan penyedia layanan. Selain itu,Perjanjian layanan tersebut diperlukan juga sebagai jaminan kualitas help desk yang dapat disepakati oleh penyedia layanan dan pengguna layanan yang merupakan pengguna SAP pada PT. Pupuk Indonesia dan anak perusahaannya. Hal tersebut bertujuan untuk menyelaraskan bisnis dengan kualitas layanan serta menentukan kebutuhan dan harapan pelanggan dalam sebuah perjanjian antara penyedia layanan dan pengguna layanan. Dari permasalahan tersebut, maka diperlukan pembuatan dokumen Service Level Requirement, Service Level Agreement dan juga Operational Level Agreement pada help desk SAP, dengan dilakukan observasi dokumen dan wawancara pada pihak pengguna layanan dan penyedia layanan, maka setelah itu dibuatlah dokumen Service Level management tersebut berdasarkan ITIL Versi 2011.

  20. Evaluation method for the proficiency level of an operating myoelectric hand using EMG signals.

    Science.gov (United States)

    Kita, Kahori; Kato, Ryu; Yokoi, Hiroshi

    2010-01-01

    To evaluate the proficiency level of an operating myoelectric hand, we proposed an evaluation index consisting of the accuracy and the reproducibility of electromyography (EMG) signal patterns. Our proposed method is not an absolute evaluation because we use bio-signals, so it is necessary to verify the correlation between the proposed index and performance evaluation to confirm the usefulness of the index. Therefore, we conducted classification tests on eight forearm motions and verified the correlation between the proposed method and the classification rate. There was a strong correlation between the accuracy and the classification rate. In addition, if the accuracy was high, high reproducibility led to an increase in the classification rate. We conclude that the proposed method can evaluate the proficiency level of a myoelectric hand.

  1. The ATLAS trigger - high-level trigger commissioning and operation during early data taking

    CERN Document Server

    Goncalo, R; Achenbach, R; Adragna, P; Aielli, G; Aleksandrov, E; Aleksandrov, I; Aloisio, A; Alviggi, M G; Amorim, A; Anderson, K; Andrei, V; Anduaga, X; Antonelli, S; Aracena, I; Ask, S; Asquith, L; Avolio, G; Backlund, S; Badescu, E; Bahat Treidel, O; Baines, J; Barnett, B M; Barria, P; Bartoldus, R; Batreanu, S; Bauss, B; Beck, H P; Bee, C; Bell, P; Bell, W H; Bellagamba, L; Bellomo, M; Ben Ami, S; Bendel, M; Benhammou, Ya; Benslama, K; Berge, D; Berger, N; Berry, T; Bianco, M; Biglietti, M; Blair, R R; Bogaerts, A; Bohm, C; Bold, T; Booth, J R A; Boscherini, D; Bosman, M; Boyd, J; Brawn, I P; Brelier, B; Bressler, S; Bruni, A; Bruni, G; Buda, S; Burckhart-Chromek, D; Buttar, C; Camarri, P; Campanelli, M; Canale, V; Caprini, M; Caracinha, D; Cardarelli, R; Carlino, G; Casadei, D; Casado, M P; Cataldi, G; Cerri, A; Charlton, D G; Chiodini, G; Ciapetti, G; Cimino, D; Ciobotaru, M; Clements, D; Coccaro, A; Coluccia, M R; Conde-Muíño, P; Constantin, S; Conventi, F; Corso-Radu, A; Costa, M J; Coura Torres, R; Cranfield, R; Cranmer, K; Crone, G; Curtis, C J; Dam, M; Damazio, D; Davis, A O; Dawson, I; Dawson, J; De Almeida Simoes, J; De Cecco, S; De Pedis, D; De Santo, A; DeAsmundis, R; DellaPietra, M; DellaVolpe, D; Delsart, P -A; Demers, S; Di Mattia, A; Di Ciaccio, A; Di Girolamo, A; Dionisi, C; Djilkibaev, R; Dobinson, Robert W; Dobson, M; Dogaru, M; Dotti, A; Dova, M; Drake, G; Dufour, M -A; Eckweiler, S; Ehrenfeld, W; Eifert, T; Eisenhandler, E F; Ellis, Nick; Emeliyanov, D; Enoque Ferreira de Lima, D; Ermoline, Y; Eschrich, I; Etzion, E; Facius, K; Falciano, S; Farthouat, P; Faulkner, P J W F; Feng, E; Ferland, J; Ferrari, R; Ferrer, M L; Fischer, G; Fonseca-Martin, T; Francis, D; Fukunaga, C; Föhlisch, F; Gadomski, S; Garitaonandia Elejabarrieta, H; Gaudio, G; Gaumer, O; Gee, C N P; George, S; Geweniger, C; Giagu, S; Gillman, A R; Giusti, P; Gorini, B; Gorini, E; Gowdy, S; Grabowska-Bold, I; Grancagnolo, F; Grancagnolo, S; Green, B; Galllno, P; Haas, S; Haberichter, W; Hadavand, H; Haeberli, C; Haller, J; Hamilton, A; Hanke, P; Hansen, J R; Hasegawa, Y; Hauschild, M; Hauser, R; Head, S; Hellman, S; Hidvegi, A; Hillier, S J; Höcker, A; Hrynóva, T; Hughes-Jones, R; Huston, J; Iacobucci, G; Idarraga, J; Iengo, P; Igonkina, O; Ikeno, M; Inada, M; Ishino, M; Iwasaki, H; Izzo, V; Jain, V; Johansen, M; Johns, K; Joos, M; Kadosaka, T; Kajomovitz, E; Kama, S; Kanaya, N; Kawagoe, K; Kawamoto, T; Kazarov, A; Kehoe, R; Khoriauli, G; Kieft, G; Kilvington, G; Kirk, J; Kiyamura, H; Klofver, P; Klous, S; Kluge, E -E; Kobayashi, T; Kolos, S; Kono, T; Konstantinidis, N; Korcyl, K; Kordas, K; Kotov, V; Krasznahorkay, A; Kubota, T; Kugel, A; Kuhn, D; Kurashige, H; Kurasige, H; Kuwabara, T; Kwee, R; Landon, M; Lankford, A; LeCompte, T; Leahu, L; Leahu, M; Ledroit, F; Lehmann-Miotto, G; Lei, X; Lellouch, D; Lendermann, V; Levinson, L; Leyton, M; Li, S; Liberti, B; Lifshitz, R; Lim, H; Lohse, T; Losada, M; Luci, C; Luminari, L; Lupu, N; Mahboubi, K; Mahout, G; Mapelli, L; Marchese, F; Martin, B; Martin, B T; Martínez, A; Marzano, F; Masik, J; McMahon, T; McPherson, R; Medinnis, M; Meessen, C; Meier, K; Meirosu, C; Messina, A; Migliaccio, A; Mikenberg, G; Mincer, A; Mineev, M; Misiejuk, A; Mönig, K; Monticelli, F; Moraes, A; Moreno, D; Morettini, P; Murillo Garcia, R; Nagano, K; Nagasaka, Y; Negri, A; Némethy, P; Neusiedl, A; Nisati, A; Niwa, T; Nomachi, M; Nomoto, H; Nozaki, M; Nozicka, M; Ochi, A; Ohm, C; Okumura, Y; Omachi, C; Osculati, B; Oshita, H; Osuna, C; Padilla, C; Panikashvili, N; Parodi, F; Pasqualucci, E; Pastore, F; Patricelli, S; Pauly, T; Pectu, M; Perantoni, M; Perera, V; Perera, V J O; Pérez, E; Pérez-Réale, V; Perrino, R; Pessoa Lima Junior, H; Petersen, J; Petrolo, E; Piegaia, R; Pilcher, J E; Pinto, F; Pinzon, G; Polini, A; Pope, B; Potter, C; Prieur, D P F; Primavera, M; Qian, W; Radescu, V; Rajagopalan, S; Renkel, P; Rescigno, M; Rieke, S; Risler, C; Riu, I; Robertson, S; Roda, C; Rodríguez, D; Rogriquez, Y; Roich, A; Romeo, G; Rosati, S; Ryabov, Yu; Ryan, P; Rühr, F; Sakamoto, H; Salamon, A; Salvatore, D; Sankey, D P C; Santamarina, C; Santamarina-Rios, C; Santonico, R; Sasaki, O; Scannicchio, D; Scannicchio, D A; Schiavi, C; Schlereth, J L; Schmitt, K; Scholtes, I; Schooltz, D; Schuler, G; Schultz-Coulon, H -C; Schäfer, U; Scott, W; Segura, E; Sekhniaidze, G; Shimbo, N; Sidoti, A; Silva, L; Silverstein, S; Siragusa, G; Sivoklokov, S; Sloper, J E; Smizanska, M; Solfaroli, E; Soloviev, I; Soluk, R; Spagnolo, S; Spila, F; Spiwoks, R; Staley, R J; Stamen, R; Stancu, S; Steinberg, P; Stelzer, J; Stradling, A; Strom, D; Strong, J; Su, D; Sugaya, Y; Sugimoto, T; Sushkov, S; Sutton, M; Szymocha, T; Takahashi, Y; Takeda, H; Takeshita, T; Tanaka, S; Tapprogge, S; Tarem, S; Tarem, Z; Teixeira-Dias, P; Thomas, J P; Tokoshuku, K; Tomoto, M; Torrence, E; Touchard, F

    2008-01-01

    The ATLAS experiment is one of the two general-purpose experiments due to start operation soon at the Large Hadron Collider (LHC). The LHC will collide protons at a centre of mass energy of 14~TeV, with a bunch-crossing rate of 40~MHz. The ATLAS three-level trigger will reduce this input rate to match the foreseen offline storage capability of 100-200~Hz. This paper gives an overview of the ATLAS High Level Trigger focusing on the system design and its innovative features. We then present the ATLAS trigger strategy for the initial phase of LHC exploitation. Finally, we report on the valuable experience acquired through in-situ commissioning of the system where simulated events were used to exercise the trigger chain. In particular we show critical quantities such as event processing times, measured in a large-scale HLT farm using a complex trigger menu.

  2. Crystallization In High Level Waste (HLW) Glass Melters: Operational Experience From The Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K. M.

    2014-02-27

    processing strategy for the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The basis of this alternative approach is an empirical model predicting the crystal accumulation in the WTP glass discharge riser and melter bottom as a function of glass composition, time, and temperature. When coupled with an associated operating limit (e.g., the maximum tolerable thickness of an accumulated layer of crystals), this model could then be integrated into the process control algorithms to formulate crystal tolerant high level waste (HLW) glasses targeting higher waste loadings while still meeting process related limits and melter lifetime expectancies. This report provides a review of the scaled melter testing that was completed in support of the Defense Waste Processing Facility (DWPF) melter. Testing with scaled melters provided the data to define the DWPF operating limits to avoid bulk (volume) crystallization in the un-agitated DWPF melter and provided the data to distinguish between spinels generated by K-3 refractory corrosion versus spinels that precipitated from the HLW glass melt pool. This report includes a review of the crystallization observed with the scaled melters and the full scale DWPF melters (DWPF Melter 1 and DWPF Melter 2). Examples of actual DWPF melter attainment with Melter 2 are given. The intent is to provide an overview of lessons learned, including some example data, that can be used to advance the development and implementation of an empirical model and operating limit for crystal accumulation for WTP. Operation of the first and second (current) DWPF melters has demonstrated that the strategy of using a liquidus temperature predictive model combined with a 100 °C offset from the normal melter operating temperature of 1150 °C (i.e., the predicted liquidus temperature (TL) of the glass must be 1050 °C or less) has been successful in preventing any detrimental accumulation of spinel in the DWPF melt pool, and spinel has not been

  3. Clinical and Prognostic Significance of Preoperative Plasma Fibrinogen Levels in Patients with Operable Breast Cancer.

    Directory of Open Access Journals (Sweden)

    Yu Mei

    Full Text Available Elevated plasma fibrinogen levels are associated with tumor progression and poor outcomes in different cancer patients. The objective of this study was to investigate the clinical and prognostic value of preoperative plasma fibrinogen levels in patients with operable breast cancer.Two hundred and twenty-three patients diagnosed with breast cancer were retrospectively evaluated in this study. Plasma fibrinogen levels were examined before treatment and analyzed along with patient clinicopathological parameters, disease-free survival (DFS and overall survival (OS. Both univariate and multivariate analyses were performed to identify the clinicopathological parameters associated with DFS and OS.Elevated preoperative plasma fibrinogen levels were directly associated with age of diagnose (≤47 vs. >47, p<0.001, menopause (yes vs. no, p<0.001, tumor size (T1&T2 vs. T3&T4, p = 0.033, tumor stage (I vs. II vs. III, p = 0.034 and lymph node involvement (N = 0 vs. 1≤N≤3 vs. N≥4, p<0.001, but not with histological grade, molecular type and other Immunohistochemical parameters (ER, PR, HER2 and Ki-67. In a univariate survival analysis, tumor stage, tumor size, lymph node involvement (p<0.001/p<0.001 and plasma fibrinogen (p<0.001/p<0.001 levels were associated with disease-free and overall survival, but just lymph nodes involvement (p<0.001, hazard ratio [HR] = 2.9, 95% confidence interval [CI] = 1.6-5.3/p = 0.006, HR = 3.2, 95% CI = 1.4-7.3 and plasma fibrinogen levels (p = 0.006, HR = 3.4, 95% CI = 1.4-8.3/p = 0.002, HR = 10.1, 95% CI = 2.3-44.6 were associated with disease-free and overall survival in a multivariate survival analysis, respectively.This study demonstrates that elevated preoperative plasma fibrinogen levels are associated with breast cancer progression and are independently associated with a poor prognosis in patients with operable breast cancer.

  4. Low-Voltage Hall Thruster Mode Transitions

    Science.gov (United States)

    2014-06-01

    Technical Paper 3. DATES COVERED (From - To) June 2014- July 2014 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER In-House Low-Voltage Hall Thruster Mode...ABSTRACT Past investigations of the 6kW-class H6 Hall thruster during low-voltage operation revealed two operating modes, corresponding to the...topologies were characterized for the H6 Hall thruster from 100V to 200V discharge, with variation in cathode flow fraction, cathode position inside and

  5. Impact of some field factors on inhalation exposure levels to bitumen emissions during road paving operations.

    Science.gov (United States)

    Deygout, François; Auburtin, Guy

    2015-03-01

    Variability in occupational exposure levels to bitumen emissions has been observed during road paving operations. This is due to recurrent field factors impacting the level of exposure experienced by workers during paving. The present study was undertaken in order to quantify the impact of such factors. Pre-identified variables currently encountered in the field were monitored and recorded during paving surveys, and were conducted randomly covering current applications performed by road crews. Multivariate variance analysis and regressions were then used on computerized field data. The statistical investigations were limited due to the relatively small size of the study (36 data). Nevertheless, the particular use of the step-wise regression tool enabled the quantification of the impact of several predictors despite the existing collinearity between variables. The two bitumen organic fractions (particulates and volatiles) are associated with different field factors. The process conditions (machinery used and delivery temperature) have a significant impact on the production of airborne particulates and explain up to 44% of variability. This confirms the outcomes described by previous studies. The influence of the production factors is limited though, and should be complemented by studying factors involving the worker such as work style and the mix of tasks. The residual volatile compounds, being part of the bituminous binder and released during paving operations, control the volatile emissions; 73% of the encountered field variability is explained by the composition of the bitumen batch.

  6. Greenhouse Gas Emissions from Ground Level Area Sources in Dairy and Cattle Feedyard Operations

    Directory of Open Access Journals (Sweden)

    Calvin B. Parnell

    2011-08-01

    Full Text Available A protocol that consisted of an isolation flux chamber and a portable gas chromatograph was used to directly quantify greenhouse gas (GHG emissions at a dairy and a feedyard operation in the Texas Panhandle. Field sampling campaigns were performed 5 consecutive days only during daylight hours from 9:00 am to 7:00 pm each day. The objective of this research was to quantify and compare GHG emission rates (ERs from ground level area sources (GLAS at dairy and cattle feedyard operations during the summer. A total of 74 air samples using flux chamber were collected from the barn (manure lane and bedding area, loafing pen, open lot, settling basin, lagoons, and compost pile within the dairy operation. For the cattle feedyard, a total of 87 air samples were collected from four corner pens of a large feedlot, runoff holding pond, and compost pile. Three primary GHGs (methane, carbon dioxide, and nitrous oxide were measured and quantified from both operations. The aggregate estimated ERs for CH4, CO2, and N2O were 836, 5573, 3.4 g hd−1 d−1 (collectively 27.5 kg carbon dioxide equivalent (CO2e hd−1 d−1, respectively, at the dairy operation. The aggregate ERs for CH4, CO2, and N2O were 3.8, 1399, 0.68 g hd−1 d−1 (1.7 kg CO2e hd−1 d−1, respectively, from the feedyard. The estimated USEPA GHG ERs were about 13.2 and 1.16 kg CO2e hd−1 d−1, respectively, for dairy and feedyard operations. Aggregate CH4, CO2 and N2O ERs at the dairy facility were about 219, 4 and 5 times higher, respectively, than those at the feedyard. At the dairy, average CH4 ERs estimated from the settling basin, primary and secondary lagoons were significantly higher than those from the other GLAS, contributing about 98% of the aggregate CH4 emission. The runoff holding pond and pen surface of the feedyard contributed about 99% of the aggregate CH4 emission. Average CO2 and N2O ERs estimated from the pen surface area were significantly higher than those estimated from

  7. Operational Monitoring of GOME-2 and IASI Level 1 Product Processing at EUMETSAT

    Science.gov (United States)

    Livschitz, Yakov; Munro, Rosemary; Lang, Rüdiger; Fiedler, Lars; Dyer, Richard; Eisinger, Michael

    2010-05-01

    The growing complexity of operational level 1 radiance products from Low Earth Orbiting (LEO) platforms like EUMETSATs Metop series makes near-real-time monitoring of product quality a challenging task. The main challenge is to provide a monitoring system which is flexible and robust enough to identify and to react to anomalies which may be previously unknown to the system, as well as to provide all means and parameters necessary in order to support efficient ad-hoc analysis of the incident. The operational monitoring system developed at EUMETSAT for monitoring of GOME-2 and IASI level 1 data allows to perform near-real-time monitoring of operational products and instrument's health in a robust and flexible fashion. For effective information management, the system is based on a relational database (Oracle). An Extract, Transform, Load (ETL) process transforms products in EUMETSAT Polar System (EPS) format into relational data structures. The identification of commonalities between products and instruments allows for a database structure design in such a way that different data can be analyzed using the same business intelligence functionality. An interactive analysis software implementing modern data mining techniques is also provided for a detailed look into the data. The system is effectively used for day-to-day monitoring, long-term reporting, instrument's degradation analysis as well as for ad-hoc queries in case of an unexpected instrument or processing behaviour. Having data from different sources on a single instrument and even from different instruments, platforms or numerical weather prediction within the same database allows effective cross-comparison and looking for correlated parameters. Automatic alarms raised by checking for deviation of certain parameters, for data losses and other events significantly reduce time, necessary to monitor the processing on a day-to-day basis.

  8. High-voltage integrated transmitting circuit with differential driving for CMUTs

    DEFF Research Database (Denmark)

    Llimos Muntal, Pere; Larsen, Dennis Øland; Færch, Kjartan Ullitz

    2016-01-01

    In this paper, a high-voltage integrated differential transmitting circuit for capacitive micromachined ultrasonic transducers (CMUTs) used in portable ultrasound scanners is presented. Due to its application, area and power consumption are critical and need to be minimized. The circuitry...... is designed and implemented in AMS 0.35 μ m high-voltage process. Measurements are performed on the fabricated integrated circuit in order to assess its performance. The transmitting circuit consists of a low-voltage control logic, pulse-triggered level shifters and a differential output stage that generates...... pulses at differential voltage levels of 60, 80 and 100 V, a frequency up to 5 MHz and a measured driving strength of 2.03 V/ns with the CMUT electrical model connected. The total on-chip area occupied by the transmitting circuit is 0.18 mm2 and the power consumption at the ultrasound scanner operation...

  9. Levels of vibration transmitted to the operator of the tractor equipped with front axle suspension

    Directory of Open Access Journals (Sweden)

    Daniele Pochi

    2013-09-01

    Full Text Available In recent years the comfort and the preservation of the health of the operators became central issues in the evolution of agricultural machinery and led to the introduction of devices aimed at improving working conditions. Thereby, for instance, the presence of air conditioner, soundproof cab and driver seat suspension became normal on agricultural tractors. The vibrations are one of the most complex issues to deal with, being determined by the characteristics and interaction of elements such as tyres, axles, mainframe, cab and seat suspension. In this respect, manufacturers are trying to improve their products, even integrating these elements with new devices such as the suspension on the front axle of the tractor, aimed at reducing the level of vibrations during the transfers at high speed. One of these underwent tests at CRA-ING. Since its purpose is to reduce the level of vibration transmitted to the driver, their measurements in different points of the tractor and in different operating conditions, were compared in order to evaluate the effectiveness of the device, expressed as time of exposure. The suspension system of the front axle is designed to absorb the oscillations (especially pitching determined by irregularities in the road surface, allowing an increased control of the vehicle at high speed, as demonstrated by the test results and confirmed by the driving impressions outlined by the operator. The action of the device under these conditions results in an increase of the exposure time, important fact because of the relevance of the road transfer operations of tractors with mounted implements or trailers to tow and of the tendency to increase the speed limit for the road tractors (in Germany were brought to 50 km h–1 for several years. The action just described is less evident with increasing irregularity of the road surface and with the decrease of the travel speed. Nevertheless, in such conditions, the device appears to

  10. Changes in operant behavior of rats exposed to lead at the accepted no-effect level.

    Science.gov (United States)

    Gross-Selbeck, E; Gross-Selbeck, M

    1981-11-01

    After weaning, male and female Wistar rats were fed a daily diet containing 1 g lead acetate/kg food until a level of about 20 micrograms/100 mL blood was obtained. The male rats were subjected to the different behavioral tests, whereas the females were mated to untreated males and further exposed until weaning of the offspring. Behavioral testing of the male offspring was performed between 3 and 4 months of age. General behavior of both groups was tested in the open-field task including locomotion, local movements, and emotionality. The conditioned instrumental behavior was tested in the Skinner box from simple to more complex programs. The blood-lead level was measured by flameless atomic absorption spectrometry. No behavioral changes became apparent in the open-field task and in the preliminary operant training. In the more complex programs (DRH = Differential Reinforcement of High Rates), the rats exposed to lead after weaning showed slight changes of DRH performance. By contrast, in pre- and neonatally exposed animals, DRH performance was significantly increased, although blood-lead levels had returned to normal at the time of testing. A comparison of lead effects in animals to possible effects in man is discussed in this paper, and it is concluded that lead exposure to man at doses which presently are suggested to be innocuous may result in subclinical functional changes of the central nervous system.

  11. Quick-low-density parity check and dynamic threshold voltage optimization in 1X nm triple-level cell NAND flash memory with comprehensive analysis of endurance, retention-time, and temperature variation

    Science.gov (United States)

    Doi, Masafumi; Tokutomi, Tsukasa; Hachiya, Shogo; Kobayashi, Atsuro; Tanakamaru, Shuhei; Ning, Sheyang; Ogura Iwasaki, Tomoko; Takeuchi, Ken

    2016-08-01

    NAND flash memory’s reliability degrades with increasing endurance, retention-time and/or temperature. After a comprehensive evaluation of 1X nm triple-level cell (TLC) NAND flash, two highly reliable techniques are proposed. The first proposal, quick low-density parity check (Quick-LDPC), requires only one cell read in order to accurately estimate a bit-error rate (BER) that includes the effects of temperature, write and erase (W/E) cycles and retention-time. As a result, 83% read latency reduction is achieved compared to conventional AEP-LDPC. Also, W/E cycling is extended by 100% compared with conventional Bose-Chaudhuri-Hocquenghem (BCH) error-correcting code (ECC). The second proposal, dynamic threshold voltage optimization (DVO) has two parts, adaptive V Ref shift (AVS) and V TH space control (VSC). AVS reduces read error and latency by adaptively optimizing the reference voltage (V Ref) based on temperature, W/E cycles and retention-time. AVS stores the optimal V Ref’s in a table in order to enable one cell read. VSC further improves AVS by optimizing the voltage margins between V TH states. DVO reduces BER by 80%.

  12. Sequential circuit design for radiation hardened multiple voltage integrated circuits

    Science.gov (United States)

    Clark, Lawrence T.; McIver, III, John K.

    2009-11-24

    The present invention includes a radiation hardened sequential circuit, such as a bistable circuit, flip-flop or other suitable design that presents substantial immunity to ionizing radiation while simultaneously maintaining a low operating voltage. In one embodiment, the circuit includes a plurality of logic elements that operate on relatively low voltage, and a master and slave latches each having storage elements that operate on a relatively high voltage.

  13. Propagation of disturbances as voltage fluctuations in transmission networks

    Directory of Open Access Journals (Sweden)

    Albert Hermina

    2016-08-01

    Full Text Available Significant changes occurred in the power system in Romania in recent years by reducing the power used in the system, the number of classic power sources in operation as well as by implementing renewable energy sources, have determined short circuit power reduction (node rigidity in the points where disturbing users are connected, that in the absence of adequate measures, result in disturbances above acceptable levels. The paper analyzes two power systems areas in which are connected users that cause voltage fluctuation. Disturbances as voltage fluctuations resulting in these nodes may exceed the acceptable values and can spread in the transmission network affecting power quality over large system areas. The analysis conducted reveals the influence of short circuit power in nodes where these users are connected and highlights the fact that in some cases (e.g. lines out of operation for maintenance, shutdown of classic units in the area the disturbances in the transmission network sent to the users at lower voltages may have values above those allowed. Technical Code of existing power transmission network makes no reference to voltage fluctuations, as a rule, in the electricity transmission network was considered that this phenomenon should not exist.

  14. Determine Operating Reactor to Use for the 2016 PCI Level 1 Milestone

    Energy Technology Data Exchange (ETDEWEB)

    Clarno, Kevin T. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2016-01-30

    The Consortium for Advanced Simulation of Light Water Reactors (LWRs) (CASL) Level 1 milestone to “Assess the analysis capability for core-wide [pressurized water reactor] PWR Pellet- Clad Interaction (PCI) screening and demonstrate detailed 3-D analysis on selected sub-region” (L1:CASL.P13.03) requires a particular type of nuclear power plant for the assessment. This report documents the operating reactor and cycles chosen for this assessment in completion of the physics integration (PHI) milestone to “Determine Operating Reactor to use for PCI L1 Milestone” (L3:PHI.CMD.P12.02). Watts Bar Unit 1 experienced (at least) one fuel rod failure in each of cycles 6 and 7, and at least one was deemed to be duty related rather than being primarily related to a manufacturing defect or grid effects. This brief report documents that the data required to model cycles 1–12 of Watts Bar Unit 1 using VERA-CS contains sufficient data to model the PHI portion of the PCI challenge problem. A list of additional data needs is also provided that will be important for verification and validation of the BISON results.

  15. Levels of induced pressure and compaction as caused by forest harvesting operations

    Directory of Open Access Journals (Sweden)

    Paula Cristina Caruana Martins

    2013-03-01

    Full Text Available This study aimed to determine levels of pressure and compaction induced by forest harvesting operations in a Red Latosol (LV under planted eucalyptus. Undisturbed soil samples were collected from layers 0-3 and 15-18 cm and then used in a uniaxial compression test. Sampling was done before and after harvesting operations. Equipment being evaluated included: harvester, feller buncher, forwarder, self-loading adapted tractor, standard truck, wide-tire truck and grapple saw. Average pressures induced by the grapple saw were 320 kPa and 272 kPa, causing compaction in 80% and 20% of samples respectively from layers 0-3 cm and 15-18 cm, which indicates substantial degradation of soil structure in areas where timber is processed. In layer 0-3 cm, average pressures induced by the harvester and by the feller buncher were 240 kPa and 263 kPa respectively, while in layer 15-18 cm pressures were 234 kPa and 239 kPa respectively. The feller buncher caused higher soil compaction than the harvester in layer 0-3 cm, yet in layer 15-18 cm they had similar behavior. All timber forwarding equipment led to soil compaction. The wide-tire truck was the forwarding implement promoting the highest rate of compaction, in both residue conditions. Traffic intensity 7 promoted the highest rate of soil compaction.

  16. Operational intervention levels in a nuclear emergency, general concepts and a probabilistic approach

    Energy Technology Data Exchange (ETDEWEB)

    Lauritzen, B. [ed.; Damkjaer, A. [Risoe National Laboratory, Roskilde (Denmark); Baeverstam, U. [Swedish Radiation Protection Institute, Stockholm (Sweden); Naadland Holo, E. [Norwegian Radiation Protection Authority, Oslo (Norway); Sinkko, K. [Radiation and Nuclear Safety Authority, STUK, HElsinki (Finland)

    1997-12-01

    This report deals with Operational Intervention Levels (OILs) in a nuclear or radiation emergency. OILs are defined as the values of environmental measurements, in particular dose rate measurements, above which specific protective actions should be carried out in emergency exposure situations. The derivation and the application of OILs are discussed, and an overview of the presently adopted values is provided, with emphasis on the situation in the Nordic countries. A new, probabilistic approach to derive OILs is presented and the method is illustrated by calculating dose rate OILs in a simplified setting. Contrary to the standard approach, the probabilistic approach allows for optimization of OILs. It is argued, that optimized OILs may be much larger than the presently adopted or suggested values. It is recommended, that the probabilistic approach is further developed and employed in determining site specific OILs and in optimizing environmental measuring strategies. (au). 18 refs.

  17. Alternative Vibration Protecting Systems for Men-Operators of Transport Machines: Modern Level and Prospects

    Science.gov (United States)

    LEE, C.-M.; GOVERDOVSKIY, V. N.

    2002-01-01

    The up-to-date level and a few of the prospects are considered in transport biomechanical vibration protection systems. An experimental estimation of the maximum capabilities of traditional vibration protecting mechanisms (VPMs) used in driver seats is given. Some of the points of synthesis and research for the adaptive VPMs, called mechanisms of elastic links with small stiffness (ELSS-mechanisms) are presented. They contain a novel object of control: non-linear elastic elements with variable torsion “negative” stiffness (TNS). These TNS-elements help to optimize VPMs according to certain criteria and give them invariant structural and functional properties. Some experimental results are presented, and they correspond well with theoretical predictions. An approach is demonstrated for grade of quality of vibration protection of the men-operators of land unsuspended machines and pilots of helicopters.

  18. Overview of Low-Level Waste Disposal Operations at the Nevada Test Site

    Energy Technology Data Exchange (ETDEWEB)

    DOE/Navarro

    2007-02-01

    The U.S. Department of Energy, National Nuclear Security Administration Nevada Site Office Environmental Management Program is charged with the responsibility to carry out the disposal of on-site and off-site generated low-level radioactive waste at the Nevada Test Site. Core elements of this mission are ensuring that disposal take place in a manner that is safe and cost-effective while protecting workers, the public, and the environment. This paper focuses on giving an overview of the Nevada Test Site facilities regarding currant design of disposal. In addition, technical attributes of the facilities established through the site characterization process will be further described. An update on current waste disposal volumes and capabilities will also be provided. This discussion leads to anticipated volume projections and disposal site requirements as the Nevada Test Site disposal operations look towards the future.

  19. Microprocessor-controlled, programmable ramp voltage generator

    Energy Technology Data Exchange (ETDEWEB)

    Hopwood, J.

    1978-11-01

    A special-purpose voltage generator has been developed for driving the quadrupole mass filter of a residual gas analyzer. The generator is microprocessor-controlled with desired ramping parameters programmed by setting front-panel digital thumb switches. The start voltage, stop voltage, and time of each excursion are selectable. A maximum of five start-stop levels may be pre-selected for each program. The ramp voltage is 0 to 10 volts with sweep times from 0.1 to 999.99 seconds.

  20. Voltage sag source location based on instantaneous energy detection

    DEFF Research Database (Denmark)

    Chen, Zhe; Xinzhou, Dong; Wei, Kong

    2007-01-01

    Voltage sag is the major power quality problem, which could disrupt the operation of sensitive equipment. This paper presents the applications of instantaneous energy direction for voltage sag source detection. Simulations have been performed to provide the analysis for system with distributed ge...... generation units. The studies show that the presented method can effectively detect the location of the voltage sag source....

  1. VOLTAGE STABILITY IMPROVEMENT IN POWER SYSTEM BY USING STATCOM

    Directory of Open Access Journals (Sweden)

    A.ANBARASAN

    2012-11-01

    Full Text Available Voltage stability problems usually occur in heavily loaded systems. Nowadays the power demand increases enormously, hence in a large interconnected power system network subject to stress conditions. This situation can be handled by increasing the generation or reducing the transmission losses. When the load increases suddenly, voltage magnitude also varies beyond the permissible voltage stability limit. But the voltage magnitude must be maintained within the limit for proper operation of the system. Hence, voltage stability must be improved by providing suitable reactive power compensation. The proposed work was analyzed using IEEE 14 bus test system. The STATCOM improves the voltage stability margin of the system.

  2. Radiopacity and microhardness changes and effect of X-ray operating voltage in resin-based materials before and after the expiration date

    Directory of Open Access Journals (Sweden)

    Tirapelli Camila

    2004-01-01

    Full Text Available This study observed alteration in the radiopacity and microhardness of expired resin-based materials compared to non-expired materials and the operating characteristics of the X-ray source used. Five 2 mm-thick cured specimens were prepared for each material: composite resins (P60®, Z100®, and a compomer (Dyract AP®. Radiopacity of the specimens was evaluated comparing the density of the resin-based material to an equivalent (mm density of a 99.5% pure aluminum step wedge using a transmission densitometer. Surface microhardness measurements were carried out using a calibrated Vickers indenter on three different points of the same surface. ANOVA and Tukey tests (pre-set alpha = 0.05 revealed that expired materials showed no significant change in radiopacity. One material (Filtek P60 demonstrated lower radiopacity with lower KVp. Change in microhardness wa s statistically significant for Z100: for this material, the microhardness after expiration was significantly lower than before the expiration date.

  3. High-Voltage, Asymmetric-Waveform Generator

    Science.gov (United States)

    Beegle, Luther W.; Duong, Tuan A.; Duong, Vu A.; Kanik, Isik

    2008-01-01

    The shapes of waveforms generated by commercially available analytical separation devices, such as some types of mass spectrometers and differential mobility spectrometers are, in general, inadequate and result in resolution degradation in output spectra. A waveform generator was designed that would be able to circumvent these shortcomings. It is capable of generating an asymmetric waveform, having a peak amplitude as large as 2 kV and frequency of several megahertz, which can be applied to a capacitive load. In the original intended application, the capacitive load would consist of the drift plates in a differential-mobility spectrometer. The main advantage to be gained by developing the proposed generator is that the shape of the waveform is made nearly optimum for various analytical devices requiring asymmetric-waveform such as differential-mobility spectrometers. In addition, this waveform generator could easily be adjusted to modify the waveform in accordance with changed operational requirements for differential-mobility spectrometers. The capacitive nature of the load is an important consideration in the design of the proposed waveform generator. For example, the design provision for shaping the output waveform is based partly on the principle that (1) the potential (V) on a capacitor is given by V=q/C, where C is the capacitance and q is the charge stored in the capacitor; and, hence (2) the rate of increase or decrease of the potential is similarly proportional to the charging or discharging current. The proposed waveform generator would comprise four functional blocks: a sine-wave generator, a buffer, a voltage shifter, and a high-voltage switch (see Figure 1). The sine-wave generator would include a pair of operational amplifiers in a feedback configuration, the parameters of which would be chosen to obtain a sinusoidal timing signal of the desired frequency. The buffer would introduce a slight delay (approximately equal to 20 ns) but would otherwise

  4. Enabling the MLSpOC (Multi-Level Space Operations Center) of the Future

    Science.gov (United States)

    Missal, D.

    2012-09-01

    accredited today at multiple sites both CONUS and OCONUS. It is designed to assist information systems developers achieve DCID 6/3 Protection Level 4 or 5 (PL4 or PL5) or DoD SABI C&A for SECRET-to-UNCLASSIFIED systems (PL3). The product is on the DoD/DNI Unified Cross-domain Management Office's (UCDMO) Baseline of accredited solutions, and is the only solution on the Baseline which the Government considers to be an "All-in-One" approach to the Cross-domain Security challenge. Our solution is also the only PL-4 Cloud in existence and that is deployed and operational in the entire world today (at DIA). The Space marketplace is a very unique cross-domain challenge, as a need exists for Unclassified SSA Data Sharing at a deeper and more fundamental level than anywhere else in the IC or DoD. For instance, certain Agencies and/or Programs have a requirement to share information with Partner Nations that are not considered to be "friendly" (e.g. China). Our Solution is the ONLY solution in the world today that's achieved C&A, and that is uniquely positioned to enable the Multi-level Space Operations Center (MLSpOC) of the Future.

  5. Active power filter for medium voltage networks with predictive current control

    Energy Technology Data Exchange (ETDEWEB)

    Verne, Santiago A.; Valla, Maria I. [Laboratorio de Electronica Industrial, Control e Instrumentacion (LEICI), Facultad de Ingenieria, Universidad Nacional de La Plata and CONICET, La Plata (Argentina)

    2010-12-15

    A transformer less Shunt Active Power Filter (SAPF) for medium voltage distribution networks based on Multilevel Diode Clamped Inverter is presented in this paper. Converter current control is based on a Model Predictive strategy, which gives very fast current response. Also, the algorithm includes voltage balancing capability which is essential for proper converter operation. The presented current control algorithm is naturally applicable to converters with an arbitrary number of levels with reduced computational effort by virtue of the incorporation of switching restrictions which are necessary for reliable converter operation. The performance of the proposed algorithm is evaluated by means of computer simulations. (author)

  6. Research on Energy Storage Capacity Allocation for Low Voltage Operation of the Permanent Magnetic Synchronous Generator%永磁直驱风力机低电压运行储能容量取值研究

    Institute of Scientific and Technical Information of China (English)

    朱鑫; 晁勤; 邱先智; 罗绍青; 覃金彩

    2015-01-01

    针对永磁直驱风力机低电压运行时存在的直流侧过电压问题,建立了运用超级电容器储能来解决该问题的方案,提出了超级电容器储能容量取值方法。对故障前后系统能量变化进行分析设计了储能系统充放电控制策略,结合超级电容器等效模型进行数学推导得出储能容量计算表达式。通过模拟不同深度电压跌落故障进行仿真计算,分别得出所需超级电容器储能容量。最后对比储能投入前后直流侧电压变化证明了所提出的储能容量计算方法的正确性以及储能系统控制策略的有效性。%In view of the overvoltage which occurs to the DC side when the permanent magnetic synchronous generator (PMSG)operates at a low voltage,this paper proposes to use the Super Capacitor Energy Storage (SCES),and also the rea-sonable value range of the storage capacity. Firstly,it analyzes the energy change of the system before and after the fault and designs the energy storage system charge/discharge control stra-tegy. The energy storage capacity expression is acquired by means of the mathematical derivation with super capacitor equivalent models. Simultaneously, the different depths of voltage sag faults are simulated and calculated to obtain the storage capacity of the super capacitor energy as required. Finally,comparisons of voltage changes in the DC side before and after the energy storage verify the validity of calculation method about energy storage capacities and the effectiveness of energy storage system control strategy.

  7. Overview of the Standing Operating Procedure (SOP) for the development of Provisional Advisory Levels (PALs).

    Science.gov (United States)

    Young, Robert A; Bast, Cheryl B; Wood, Carol S; Adeshina, Femi

    2009-12-01

    Provisional Advisory Levels (PALs) are concentrations in air and drinking water for priority toxic chemicals. This article summarizes the Standing Operating Procedure (SOP) currently in place for the data-driven development of chemical-specific PALs. To provide consistency and transparency, and to avoid faults of arbitrariness, the SOP was developed for guidance in deriving PAL values. Three levels (PAL 1, PAL 2, and PAL 3), distinguished by severity of toxic effects, are developed for 24-hour, 30-day, 90-day, and 2-year durations of potential drinking water and inhalation exposures for the general public. The SOP for PAL development focuses on (1) data acquisition and analysis, (2) identification of a chemical-specific critical effect, (3) selection of a quantitative point-of-departure (POD), (4) uncertainty analysis and adjustments, (5) exposure duration adjustment and extrapolation, (6) identification of special concerns and issues, and (7) verification, documentation, and dissemination of PALs. To avoid uncompromising rigidity in deriving PAL values and to allow for incorporation of new or refined methodologies, the overall procedure is fluid and subject to modification. The purpose of this publication is to provide a summary of this SOP.

  8. Mousterian bone tools from “D” level in Axlor (Dima, Vizcaya: operational sequence analysis

    Directory of Open Access Journals (Sweden)

    Mozota Holgueras, Millán

    2009-06-01

    Full Text Available This paper presents the analysis of 150 retouching tools. They are diaphisis bone splinters from the long limb bones of ungulates. They were found in level “D” at Axlor (Dima, Vizcaya, which corresponds to the last stages of Mousterian period (about 44000 BP. This level contains an abundance of Quina-type side scrapers. The study combines different approaches (taphonomy, technology, traceology and experimentation within an structure of operational sequence analysis. The role of “sparsely elaborated” tools in neanderthals disability models, and their informative potential about Middle Palaeolithic societies, are discused.

    Este artículo presenta el análisis de 150 retocadores en esquirlas diafisiarias de huesos largos de las extremidades de grandes ungulados. Provienen del nivel D de Axlor (Dima, Vizcaya, datado en el final del Musteriense (hacia 44000 BP, y caracterizado por la abundancia de raederas Quina. El trabajo combina varios enfoques (tafonómico, tecnológico, traceológico y experimental que se integran en una estructura de análisis de la cadena operativa. Se discute el papel de las llamadas industrias “poco elaboradas” en los modelos sobre las incapacidades de los neandertales, y su potencial informativo sobre las sociedades del Paleolítico medio.

  9. Crystallization In High Level Waste (HLW) Glass Melters: Operational Experience From The Savannah River Site

    Energy Technology Data Exchange (ETDEWEB)

    Fox, K. M.

    2014-02-27

    processing strategy for the Hanford Tank Waste Treatment and Immobilization Plant (WTP). The basis of this alternative approach is an empirical model predicting the crystal accumulation in the WTP glass discharge riser and melter bottom as a function of glass composition, time, and temperature. When coupled with an associated operating limit (e.g., the maximum tolerable thickness of an accumulated layer of crystals), this model could then be integrated into the process control algorithms to formulate crystal tolerant high level waste (HLW) glasses targeting higher waste loadings while still meeting process related limits and melter lifetime expectancies. This report provides a review of the scaled melter testing that was completed in support of the Defense Waste Processing Facility (DWPF) melter. Testing with scaled melters provided the data to define the DWPF operating limits to avoid bulk (volume) crystallization in the un-agitated DWPF melter and provided the data to distinguish between spinels generated by K-3 refractory corrosion versus spinels that precipitated from the HLW glass melt pool. This report includes a review of the crystallization observed with the scaled melters and the full scale DWPF melters (DWPF Melter 1 and DWPF Melter 2). Examples of actual DWPF melter attainment with Melter 2 are given. The intent is to provide an overview of lessons learned, including some example data, that can be used to advance the development and implementation of an empirical model and operating limit for crystal accumulation for WTP. Operation of the first and second (current) DWPF melters has demonstrated that the strategy of using a liquidus temperature predictive model combined with a 100 °C offset from the normal melter operating temperature of 1150 °C (i.e., the predicted liquidus temperature (TL) of the glass must be 1050 °C or less) has been successful in preventing any detrimental accumulation of spinel in the DWPF melt pool, and spinel has not been

  10. 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.

  11. High Voltage Power Converter for Large Wind Turbine

    DEFF Research Database (Denmark)

    Sztykiel, Michal

    performance has been achieved by the transformer-less turbine with a back-to-back modular multilevel converter (MMC) topology, which is single grounded only through its DC link common-mode point. It has also occurred that the results derived from losses and short circuit analyses have become advantageous over...... system operates at 20 kV level - identical as for the collector distribution network. Medium voltage operation allows the converter unit along with the filter to be installed on the base platform inside the tower. In this manner, more space in the nacelle can be flexibly accommodated by the mechanical...

  12. Voltage Sag Source Location Based on Instantaneous Energy Detection

    DEFF Research Database (Denmark)

    Chen, Zhe; Kong, Wei; Dong, Xinzhou

    2008-01-01

    Voltage sag is a major power quality problem, which could disrupt the operation of voltage-sensitive equipment. This paper presents the method based on variation components-based instantaneous energy for voltage sag source detection. Simulations have been performed to provide the thorough analysi...... for system with distributed generation units. The studies show that the presented method can effectively detect the location of voltage sag source....

  13. Reliability and Economy Based Closed-loop Operation Modes for Medium Voltage Distribution Networks%基于可靠性及经济性的中压配电网闭环运行方式

    Institute of Scientific and Technical Information of China (English)

    甘国晓; 王主丁; 周昱甬; 李磊; 李旭前

    2015-01-01

    介绍了国内外中压配电网闭环运行方式及其特点;综合考虑可靠性及经济性,建立了配电网从开环运行升级为闭环运行的净收益模型,包括一种简化的中压电缆线路可靠性指标,即系统平均停电持续时间(SAIDI)评估模型;探讨了配电网闭环运行适用范围及实施难度。研究表明,国内现有配电网“闭环设计,开环运行”的供电模式限制了供电可靠性的进一步提升。对于经济发达、负荷密度大、有分布式电源接入以及可靠性要求高的地区,在条件允许的情况下,可考虑采用闭环运行方式(主要为来自同一母线的两馈线自环);该运行方式虽然可能增加供电公司的成本,但能够在提升供电可靠性的同时保证良好的社会经济效益。%The closed-loop operation mode and features of medium voltage distribution networks at home and abroad are described.With both reliability and economy considered,a net profit model for upgrading the distribution network from open-loop operation to closed-loop operation is developed,including a simplified evaluation model of system average interruption duration index(SAIDI) for a medium voltage cable feeder.The difficulties and applicable scopes of closed-loop operation are discussed.The study results show:i)further improvement of power supply reliability is impeded because of the existing power supply mode of closed-loop design and open-loop operation for domestic distribution networks;ii) for areas of developed economy,large load density,distributed generation and high reliability requirement,the closed-loop operation mode (mainly one of two feeders from the same bus) can be considered for use conditions permitting.Despite a higher cost for the power supply company owing to the use of the closed-loop operation mode,power supply reliability is improved while good social and economic benefits are ensured at the same time.

  14. VOLTAGE REGULATORS OF SYNCHRONOUS GENERATORS

    Directory of Open Access Journals (Sweden)

    Grigorash O. V.

    2015-06-01

    Full Text Available Synchronous generators are the primary source of electrical power autonomous electrosupply systems, including backup systems. They are also used in a structure of rotating electricity converters and are widely used in renewable energy as part of wind power plants of small, mini and micro hydroelectric plants. Increasing the speed and the accuracy of the system of the voltage regulation of synchronous generators is possible due to the development of combined systems containing more stabilizers. The article illustrates the functional schemes of circuit voltage stabilizers and frequency synchronous generators (with electromagnetic excitation and permanent magnet excitation and describes the features of their work, including two and three-aggregate rotating converters of electricity used in uninterruptible power supply systems. To improve the technical characteristics of the system of stabilization we have proposed functional solutions for stabilizers of synchronous generators made on the base of direct frequency converters and using a transformer with a rotating magnetic field. To improve the reliability of and to improve the operational characteristics of the autonomous independent sources of electricity we suggest creating the main functional blocks and the elements of the stabilization system in a modular way. The functional circuit solutions of voltage regulators of synchronous generators and the characteristics of their work considered in the article, are able to improve the efficiency of pre-design work in the development of new technical solutions for stabilizing the voltage and the frequency in synchronous generators of electrosupply autonomous systems

  15. New Control Technique Applied in Dynamic Voltage Restorer for Voltage Sag Mitigation

    Directory of Open Access Journals (Sweden)

    Rosli Omar

    2010-01-01

    Full Text Available The Dynamic Voltage Restorer (DVR was a power electronics device that was able to compensate voltage sags on critical loads dynamically. The DVR consists of VSC, injection transformers, passive filters and energy storage (lead acid battery. By injecting an appropriate voltage, the DVR restores a voltage waveform and ensures constant load voltage. There were so many types of the control techniques being used in DVR for mitigating voltage sags. The efficiency of the DVR depends on the efficiency of the control technique involved in switching the inverter. Problem statement: Simulation and experimental investigation toward new algorithms development based on SVPWM. Understanding the nature of DVR and performance comparisons between the various controller technologies available. The proposed controller using space vector modulation techniques obtain higher amplitude modulation indexes if compared with conventional SPWM techniques. Moreover, space vector modulation techniques can be easily implemented using digital processors. Space vector PWM can produce about 15% higher output voltage than standard Sinusoidal PWM. Approach: The purpose of this research was to study the implementation of SVPWM in DVR. The proposed control algorithm was investigated through computer simulation by using PSCAD/EMTDC software. Results: From simulation and experimental results showed the effectiveness and efficiency of the proposed controller based on SVPWM in mitigating voltage sags in low voltage distribution systems. It was concluded that its controller also works well both in balance and unbalance conditions of voltages. Conclusion/Recommendations: The simulation and experimental results of a DVR using PSCAD/EMTDC software based on SVPWM technique showed clearly the performance of the DVR in mitigating voltage sags. The DVR operates without any difficulties to inject the appropriate voltage component to correct rapidly any anomaly in the supply voltage to keep the

  16. Coordinated Voltage Control of Active Distribution Network

    Directory of Open Access Journals (Sweden)

    Xie Jiang

    2016-01-01

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

  17. Low Voltage Ride-Through of Two-Stage Grid-Connected Photovoltaic Systems Through the Inherent Linear Power-Voltage Characteristic

    DEFF Research Database (Denmark)

    Yang, Yongheng; Sangwongwanich, Ariya; Liu, Hongpeng

    2017-01-01

    In this paper, a cost-effective control scheme for two-stage grid-connected PhotoVoltaic (PV) systems in Low Voltage Ride-Through (LVRT) operation is proposed. In the case of LVRT, the active power injection by PV panels should be limited to prevent from inverter over-current and also energy...... aggregation at the dc-link, which will challenge the dc-link capacitor lifetime if remains uncontrolled. At the same time, reactive currents should be injected upon any demand imposed by the system operators. In the proposed scheme, the two objectives can be feasibly achieved. The active power is regulated...... automatically through a proportional controller according to the voltage sag level and PV inherent characteristics (i.e., the voltage and power droop). Compared to prior-art LVRT schemes, the proposed method is cost-effective, as it is achieved by simply plugging the proportional controller into a maximum power...

  18. Voltage and Frequency Control for Future Power Systems: the ELECTRA IRP Proposal

    DEFF Research Database (Denmark)

    D’hulst, R.; Merino Fernandez, J.; Rikos, E.;

    2015-01-01

    In this paper a high level functional architecture for frequency and voltage control for the future (2030+) power system is presented. The proposal suggests a decomposition of the present organization of power system operation into a ”web of cells”. Each cell in this web is managed by a single sy...

  19. 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

  20. 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...

  1. Solving Energy Levels for SSH Hamiltonian Describing Peierls Phase Transition by Virtue of Invariant Eigen-operator Method

    Institute of Scientific and Technical Information of China (English)

    P.S. Vyas; FAN Hong-Yi; P.N. Gajjar; WU Hao; B.Y. Thakore; A.R. Jani

    2008-01-01

    We show that the recently proposed invariant eigen-operator (IEO) method can be successfully applied to solving energy levels for SSH Hamiltonian describing Peierls phase transition. The electronic energy band of compound lattice is also studied by IEO method.

  2. An approach to operational risk modeling and estimation of safety levels for deep water work class remotely operated vehicle—A case study with reference to ROSUB 6000

    Directory of Open Access Journals (Sweden)

    N. Vedachalam

    2016-04-01

    Full Text Available This paper presents a quantitative approach to operational risk modeling and estimation of safety integrity levels, required for the deep water electric work class remotely operated vehicle with reference to ROSUB6000 developed by the National Institute of Ocean Technology, India. ROSUB6000 is used for carrying out bathymetric surveys, gas hydrate surveys, poly-metallic nodule exploration, salvage operations, and meeting emergency response situations. The system is expected to be in operation for a period of 300h per year, and has to be extremely safe and reliable. Methods and models for the quantitative assessment of operational safety and estimation of safety integrity levels for ROV are seldom available in the deep water intervention industry. The safety instrumented functions implemented in the ROV should be able to meet the SIL requirements of specific mission. This study indicates that the required safety factors are implemented into the design of the state-of-the-art ROV ROSUB 6000, considering IEC 61508/61511 recommendations on Health, Safety and Environment and it is found that the system is able to meet the required SIL for seven identified functions. This paper gives the design and safety engineers in the ROV industry, an overview of the numerical operational risk assessment methods and safety-centered ROV engineering.

  3. Analytical solutions for determining extreme water levels in surge tank of hydropower station under combined operating conditions

    Science.gov (United States)

    Wang, Bingbao; Guo, Wencheng; Yang, Jiandong

    2017-06-01

    Combined operating condition usually refers to the control operating condition under which the highest and lowest water levels occur in a surge tank of hydropower station. In this paper, with the basic equations of surge analysis and nonlinear vibrational asymptotic method, analytical expressions of the worst superimposition time of surge waves in an upstream surge tank under four typical combined operating conditions (i.e. load-acceptance-then-rejection, successive load rejection, successive load acceptance and load-rejection-then-acceptance) are derived firstly. Then using these expressions, the analytical extreme water levels are determined. The analytical solutions are verified with numerical simulation results. Finally, the effect of the hydraulic resistance coefficient of surge tank on the control operating condition is investigated. The results indicate that: The analytical solutions for determining extreme water levels in surge tank under various combined operating conditions are accurate due to the good agreements between the analytical results and the numerical results. With the increase of the hydraulic resistance coefficient of surge tank, the control operating condition for the highest water level shifts from load-acceptance-then-rejection condition to successive load rejection condition, and the control operating condition for the lowest water level shifts from load-rejection-then-acceptance condition to successive load acceptance condition.

  4. Low-voltage switched-current delta-sigma modulator

    Science.gov (United States)

    Tan, Nianxiong; Eriksson, Sven

    1995-05-01

    This paper presents the design of a fully differential switched-current delta-sigma modulator using a single 3.3-V power-supply voltage. At system level, we tailor the modulator structure considering the similarity and difference of switched-capacitor and switched-current realizations. At circuit level, we propose a new switched-current memory cell and integrator with improved common mode feedback, without which low power-supply-voltage operation would not be possible. The whole modulator was implemented in a 0.8- micron double-metal digital CMOS process. It occupies an active area of 0.53 x 0.48 mm(sup 2) and consumes a current of 0.6 mA from a single 3.3-V power supply. The measured dynamic range is over 10 b.

  5. Multifunction Voltage-Mode Filter Using Single Voltage Differencing Differential Difference Amplifier

    Directory of Open Access Journals (Sweden)

    Chaichana Amornchai

    2017-01-01

    Full Text Available In this paper, a voltage mode multifunction filter based on single voltage differencing differential difference amplifier (VDDDA is presented. The proposed filter with three input voltages and single output voltage is constructed with single VDDDA, two capacitors and two resistors. Its quality factor can be adjusted without affecting natural frequency. Also, the natural frequency can be electronically tuned via adjusting of bias current. The filter can offer five output responses, high-pas (HP, band-pass (BP, band-reject (BR, low-pass (LP and all-ass (AP functions in the same circuit topology. The output response can be selected by choosing the suitable input voltage without the component matching condition and the requirement of additional double gain voltage amplifier. PSpice simulation results to confirm an operation of the proposed filter correspond to the theory.

  6. Voltage-Gated Na+ Channel Isoforms and Their mRNA Expression Levels and Protein Abundance in Three Electric Organs and the Skeletal Muscle of the Electric Eel Electrophorus electricus.

    Science.gov (United States)

    Ching, Biyun; Woo, Jia M; Hiong, Kum C; Boo, Mel V; Wong, Wai P; Chew, Shit F; Ip, Yuen K

    2016-01-01

    This study aimed to obtain the coding cDNA sequences of voltage-gated Na+ channel (scn) α-subunit (scna) and β-subunit (scnb) isoforms from, and to quantify their transcript levels in, the main electric organ (EO), Hunter's EO, Sach's EO and the skeletal muscle (SM) of the electric eel, Electrophorus electricus, which can generate both high and low voltage electric organ discharges (EODs). The full coding sequences of two scna (scn4aa and scn4ab) and three scnb (scn1b, scn2b and scn4b) were identified for the first time (except scn4aa) in E. electricus. In adult fish, the scn4aa transcript level was the highest in the main EO and the lowest in the Sach's EO, indicating that it might play an important role in generating high voltage EODs. For scn4ab/Scn4ab, the transcript and protein levels were unexpectedly high in the EOs, with expression levels in the main EO and the Hunter's EO comparable to those of scn4aa. As the key domains affecting the properties of the channel were mostly conserved between Scn4aa and Scn4ab, Scn4ab might play a role in electrogenesis. Concerning scnb, the transcript level of scn4b was much higher than those of scn1b and scn2b in the EOs and the SM. While the transcript level of scn4b was the highest in the main EO, protein abundance of Scn4b was the highest in the SM. Taken together, it is unlikely that Scna could function independently to generate EODs in the EOs as previously suggested. It is probable that different combinations of Scn4aa/Scn4ab and various Scnb isoforms in the three EOs account for the differences in EODs produced in E. electricus. In general, the transcript levels of various scn isoforms in the EOs and the SM were much higher in adult than in juvenile, and the three EOs of the juvenile fish could be functionally indistinct.

  7. Performance of Li-Ion Cells Under Battery Voltage Charge Control

    Science.gov (United States)

    Vaidyanathan, Hari; Rao, Gopalakrishna M.

    2002-01-01

    Li-ion cells manufactured by YTP, SAFT, and MSA have completed 6714, 6226, and 3441 cycles, respectively. An increase in the charge voltage limit was required in all cases to maintain the discharge voltage. SAFT and MSA cells were capable of cycling at -10 C and 0 C with an increase in the charge voltage limit, whereas Yardney cells could not be cycled. Reconditioning improved the discharge voltage of SAFT and MSA cells; it is important to note that the effect has been temporary as in Ni-H and Ni-Cd batteries. It was demonstrated that the charge operation with VT clamp at battery rather than at cell level is feasible. Continuation of testing depends on the health of the cells and on the funding situation.

  8. Low-Voltage Continuous Electrospinning Patterning.

    Science.gov (United States)

    Li, Xia; Li, Zhaoying; Wang, Liyun; Ma, Guokun; Meng, Fanlong; Pritchard, Robyn H; Gill, Elisabeth L; Liu, Ye; Huang, Yan Yan Shery

    2016-11-30

    Electrospinning is a versatile technique for the construction of microfibrous and nanofibrous structures with considerable potential in applications ranging from textile manufacturing to tissue engineering scaffolds. In the simplest form, electrospinning uses a high voltage of tens of thousands volts to draw out ultrafine polymer fibers over a large distance. However, the high voltage limits the flexible combination of material selection, deposition substrate, and control of patterns. Prior studies show that by performing electrospinning with a well-defined "near-field" condition, the operation voltage can be decreased to the kilovolt range, and further enable more precise patterning of fibril structures on a planar surface. In this work, by using solution dependent "initiators", we demonstrate a further lowering of voltage with an ultralow voltage continuous electrospinning patterning (LEP) technique, which reduces the applied voltage threshold to as low as 50 V, simultaneously permitting direct fiber patterning. The versatility of LEP is shown using a wide range of combination of polymer and solvent systems for thermoplastics and biopolymers. Novel functionalities are also incorporated when a low voltage mode is used in place of a high voltage mode, such as direct printing of living bacteria; the construction of suspended single fibers and membrane networks. The LEP technique reported here should open up new avenues in the patterning of bioelements and free-form nano- to microscale fibrous structures.

  9. Improving Low Voltage Ride Through Capability of Wind Generators Using Dynamic Voltage Restorer

    Science.gov (United States)

    Sivasankar, Gangatharan; Suresh Kumar, Velu

    2014-08-01

    The increasing wind power integration with power grid has forced the situation to improve the reliability of wind generators for stable operation. One important problem with induction generator based wind farm is its low ride through capability to the grid voltage disturbance. Any disturbance such as voltage dip may cause wind farm outages. Since wind power contribution is in predominant percentage, such outages may lead to stability problem. The proposed strategy is to use dynamic voltage controller (DVR) to compensate the voltage disturbance. The DVR provides the wind generator the ability to remain connected in grid and improve the reliability. The voltage dips due to symmetrical and unsymmetrical faults are considered for analysis. The vector control scheme is employed for fault compensation which uses software phase locked loop scheme and park dq0 transformation technique. Extensive simulation results are included to illustrate the control and operation of DVR.

  10. Comparison of an Analog Behavioral and Transistor Level Model of Operational Amplifier

    Directory of Open Access Journals (Sweden)

    Viktor Smiesko

    2008-01-01

    Full Text Available In the present time of the electronics development lot of the measure equipments are standing in a very close neighborhood of each other. The surrounding of them is then full of various signals of various frequencies and shapes. The electromagnetic influence of these equipments is important for their functionality and performance. The high frequency disturbance with the frequency of 1 MHz and more influence of course also the performance of the operational amplifiers. Lot of such circuit swith the lower power consumption are also sensitive to the very small disturbances. This paper is our contribution to the creating of an Analog Behavioral Model (ABM of the OPAMP, which is one of thevery power ful tool and can be used for the SPICE simulations. Some results of the simulations with our proposed model were compared with the measured results as well as with the SPICE simulations on the transistor level. The results showed the good agreement between the modeled and measured values.

  11. PESTOL - Framework for «Project Evaluation on Strategic, Tactical and Operational Levels»

    Directory of Open Access Journals (Sweden)

    Youcef Zidane

    2016-01-01

    Full Text Available The paper focuses on the development of the ex-post conceptual holistic framework for Project Evaluation on Strategic, Tactical and Operational Levels, the PESTOL model, by reviewing different definitions of project success and/or failure and combining the findings with the logic framework. The model reflects the project life cycle by considering all project phases, such as identification and conception. To demonstrate the relevance of the developed model, the authors applied it to a project case, the Algerian East–West Highway megaproject. The project has attracted media attention and a number of media discussions of the project have been limited to the completion of the project in a short-term perspective. In this regard, the discussions have been notably associated with delays and expenditures coming in over budget, referring to project efficiency. One reason for the media focus on these aspects alone is that they can easily be measured. The relevance of the project and its effects - whether it attains its goals and objectives measured in terms of effectiveness, including impact and sustainability - can only be verified at a later stage, after the project has delivered its results. These are much broader aspects and are therefore difficult to measure.

  12. Comparison of the Effect of Noise Levels on Stress Response in Two Different Operation Groups in an Orthopedic Surgery Room

    Directory of Open Access Journals (Sweden)

    Hasibe Baytan Yildiz

    2016-09-01

    Full Text Available Aim: The aim of this randomized, single-blinded study was to evaluate the effects of noise on hemodynamic and neuroendocrine stress response by measuring the level of noise in the surgery rooms of patients undergoing knee operations under neuroaxial anesthesia. Gerec ve Yontem: We compared patient responses from two groups of patients: those undergoing knee operations in a surgery room where the noise level (measured in decibels is high, and those undergoing meniscus operations in a surgery room with lower noise levels. The STAI, the State-Trait Anxiety Inventory (STAI-1, and the anxiety test (STAI-2wereperformed at preoperative and postoperative periods. 20 ml of blood sample was taken for basal, intraoperative 30th minute, and postoperative 1st hour measurements. Systolic, diastolic, and mean arterial blood pressures were found to be higher in the high noise level group. ACTH levels were increased during the early postoperative period and became normal during the late postoperative period in the high noise level group whereas ACTH levels were significantly decreased in the low-noise level group. Basal cortisol levels were significantly higher in the high noise level group. HCRP, an inflammatory response mediator was found to be decreased in both groups. Early and late blood glucose levels were significantly higher in the high noise group. There was a greater increase in early and late blood glucose levels in the high noise group. In the postoperative period, although the state-trait anxiety inventory (STAI-2 levels being higher in patients subject to noisier environment determines how people feel independent of the conditions and state they are in, this result made us consider that the noise the patients were subjected to in the intraoperative period may cause a stress response. Discussion: As a result we believe that standard noise levels should be achieved by reducing the factors causing high noise levels in the operating room. This will

  13. Object-based task-level control: A hierarchical control architecture for remote operation of space robots

    Science.gov (United States)

    Stevens, H. D.; Miles, E. S.; Rock, S. J.; Cannon, R. H.

    1994-01-01

    Expanding man's presence in space requires capable, dexterous robots capable of being controlled from the Earth. Traditional 'hand-in-glove' control paradigms require the human operator to directly control virtually every aspect of the robot's operation. While the human provides excellent judgment and perception, human interaction is limited by low bandwidth, delayed communications. These delays make 'hand-in-glove' operation from Earth impractical. In order to alleviate many of the problems inherent to remote operation, Stanford University's Aerospace Robotics Laboratory (ARL) has developed the Object-Based Task-Level Control architecture. Object-Based Task-Level Control (OBTLC) removes the burden of teleoperation from the human operator and enables execution of tasks not possible with current techniques. OBTLC is a hierarchical approach to control where the human operator is able to specify high-level, object-related tasks through an intuitive graphical user interface. Infrequent task-level command replace constant joystick operations, eliminating communications bandwidth and time delay problems. The details of robot control and task execution are handled entirely by the robot and computer control system. The ARL has implemented the OBTLC architecture on a set of Free-Flying Space Robots. The capability of the OBTLC architecture has been demonstrated by controlling the ARL Free-Flying Space Robots from NASA Ames Research Center.

  14. PMU-Aided Voltage Security Assessment for a Wind Power Plant: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, H.; Zhang, Y. C.; Zhang, J. J.; Muljadi, E.

    2015-04-08

    Because wind power penetration levels in electric power systems are continuously increasing, voltage stability is a critical issue for maintaining power system security and operation. The traditional methods to analyze voltage stability can be classified into two categories: dynamic and steady-state. Dynamic analysis relies on time-domain simulations of faults at different locations; however, this method needs to exhaust faults at all locations to find the security region for voltage at a single bus. With the widely located phasor measurement units (PMUs), the Thevenin equivalent matrix can be calculated by the voltage and current information collected by the PMUs. This paper proposes a method based on a Thevenin equivalent matrix to identify system locations that will have the greatest impact on the voltage at the wind power plant’s point of interconnection. The number of dynamic voltage stability analysis runs is greatly reduced by using the proposed method. The numerical results demonstrate the feasibility, effectiveness, and robustness of the proposed approach for voltage security assessment for a wind power plant.

  15. PMU-Aided Voltage Security Assessment for a Wind Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Jiang, Huaiguang; Zhang, Yingchen; Zhang, Jun Jason; Muljadi, Eduard

    2015-10-05

    Because wind power penetration levels in electric power systems are continuously increasing, voltage stability is a critical issue for maintaining power system security and operation. The traditional methods to analyze voltage stability can be classified into two categories: dynamic and steady-state. Dynamic analysis relies on time-domain simulations of faults at different locations; however, this method needs to exhaust faults at all locations to find the security region for voltage at a single bus. With the widely located phasor measurement units (PMUs), the Thevenin equivalent matrix can be calculated by the voltage and current information collected by the PMUs. This paper proposes a method based on a Thevenin equivalent matrix to identify system locations that will have the greatest impact on the voltage at the wind power plant's point of interconnection. The number of dynamic voltage stability analysis runs is greatly reduced by using the proposed method. The numerical results demonstrate the feasibility, effectiveness, and robustness of the proposed approach for voltage security assessment for a wind power plant.

  16. Framework for E-Government Inter-Operability at National Level based on the Experience of Other Countries

    Directory of Open Access Journals (Sweden)

    Mashomeh Sadeghi

    2010-04-01

    Full Text Available Inter-operability is a tool by which a link is established between systems, information and operations within an organization or organizations at a national, regional or even divisional level. Through mutual inter-operability, organizations could offer better quality of service at a lower cost. In order to inter-operate with one another and to share the needed information, organizations need to employ specific frameworks and models. The present paper intends to provide a framework for inter-operability among organizations using the experience gained by various countries in the area of E-Government inter-operability. The proposed framework encompasses various business, information, semantic and technical aspect. Each aspects in turn is comprised of different components. The Framework offered was validated using expert views.

  17. Experimental validation of prototype high voltage bushing

    Science.gov (United States)

    Shah, Sejal; Tyagi, H.; Sharma, D.; Parmar, D.; M. N., Vishnudev; Joshi, K.; Patel, K.; Yadav, A.; Patel, R.; Bandyopadhyay, M.; Rotti, C.; Chakraborty, A.

    2017-08-01

    Prototype High voltage bushing (PHVB) is a scaled down configuration of DNB High Voltage Bushing (HVB) of ITER. It is designed for operation at 50 kV DC to ensure operational performance and thereby confirming the design configuration of DNB HVB. Two concentric insulators viz. Ceramic and Fiber reinforced polymer (FRP) rings are used as double layered vacuum boundary for 50 kV isolation between grounded and high voltage flanges. Stress shields are designed for smooth electric field distribution. During ceramic to Kovar brazing, spilling cannot be controlled which may lead to high localized electrostatic stress. To understand spilling phenomenon and precise stress calculation, quantitative analysis was performed using Scanning Electron Microscopy (SEM) of brazed sample and similar configuration modeled while performing the Finite Element (FE) analysis. FE analysis of PHVB is performed to find out electrical stresses on different areas of PHVB and are maintained similar to DNB HV Bushing. With this configuration, the experiment is performed considering ITER like vacuum and electrical parameters. Initial HV test is performed by temporary vacuum sealing arrangements using gaskets/O-rings at both ends in order to achieve desired vacuum and keep the system maintainable. During validation test, 50 kV voltage withstand is performed for one hour. Voltage withstand test for 60 kV DC (20% higher rated voltage) have also been performed without any breakdown. Successful operation of PHVB confirms the design of DNB HV Bushing. In this paper, configuration of PHVB with experimental validation data is presented.

  18. Exposure levels of farmers and veterinarians to particulate matter and gases uring operational tasks in pig-fattening houses

    Directory of Open Access Journals (Sweden)

    Nele Van Ransbeeck

    2014-09-01

    Full Text Available The main objective of the study was to assess particulate matter (PM exposure levels for both the farmer and the veterinarian during different operational tasks in pig-fattening houses, and to estimate their exposure levels on a daily working basis (time-weighted average (TWA. The measured PM fractions were: inhalable and respirable PM, PM10, PM2.5 and PM1. The effects of pig age, pen floor type (conventional or low emission surface and cleaning of the pens on the personal PM exposure were also investigated. Indoor concentrations of NH[sub]3[/sub], CH[sub]4[/sub], and CO[sub]2[/sub] were additionally measured during some operational tasks. The results showed that personal exposure levels can become extremely high during some operational tasks performed by the farmer or veterinarian. The highest concentration levels were observed during feed shovelling and blood sampling, the lowest during the weighing of the pigs. For the farmer, the estimated TWA exposure levels of inhalable and respirable PM were 6.0 and 0.29 mg m[sup] -3[/sup] , respectively. These exposure levels for the veterinarian were, respectively, 10.6 and 0.74 mg m[sup] -3[/sup] . The PM concentration levels were mainly determined by the performed operational tasks. There was no significant effect of pig age, pen floor type, nor cleaning of the pens on the personal exposure levels.

  19. Exposure levels of farmers and veterinarians to particulate matter and gases during operational tasks in pig-fattening houses.

    Science.gov (United States)

    Van Ransbeeck, Nele; Van Langenhove, Herman; Michiels, Annelies; Sonck, Bart; Demeyer, Peter

    2014-01-01

    The main objective of the study was to assess particulate matter (PM) exposure levels for both the farmer and the veterinarian during different operational tasks in pig-fattening houses, and to estimate their exposure levels on a daily working basis (time-weighted average (TWA)). The measured PM fractions were: inhalable and respirable PM, PM10, PM2.5 and PM1. The effects of pig age, pen floor type (conventional or low emission surface) and cleaning of the pens on the personal PM exposure were also investigated. Indoor concentrations of NH3, CH4, and CO2 were additionally measured during some operational tasks. The results showed that personal exposure levels can become extremely high during some operational tasks performed by the farmer or veterinarian. The highest concentration levels were observed during feed shovelling and blood sampling, the lowest during the weighing of the pigs. For the farmer, the estimated TWA exposure levels of inhalable and respirable PM were 6.0 and 0.29 mg m(-3), respectively. These exposure levels for the veterinarian were, respectively, 10.6 and 0.74 mg m(-3). The PM concentration levels were mainly determined by the performed operational tasks. There was no significant effect of pig age, pen floor type, nor cleaning of the pens on the personal exposure levels.

  20. 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.

  1. Ultra-compact Marx-type high-voltage generator

    Science.gov (United States)

    Goerz, David A.; Wilson, Michael J.

    2000-01-01

    An ultra-compact Marx-type high-voltage generator includes individual high-performance components that are closely coupled and integrated into an extremely compact assembly. In one embodiment, a repetitively-switched, ultra-compact Marx generator includes low-profile, annular-shaped, high-voltage, ceramic capacitors with contoured edges and coplanar extended electrodes used for primary energy storage; low-profile, low-inductance, high-voltage, pressurized gas switches with compact gas envelopes suitably designed to be integrated with the annular capacitors; feed-forward, high-voltage, ceramic capacitors attached across successive switch-capacitor-switch stages to couple the necessary energy forward to sufficiently overvoltage the spark gap of the next in-line switch; optimally shaped electrodes and insulator surfaces to reduce electric field stresses in the weakest regions where dissimilar materials meet, and to spread the fields more evenly throughout the dielectric materials, allowing them to operate closer to their intrinsic breakdown levels; and uses manufacturing and assembly methods to integrate the capacitors and switches into stages that can be arranged into a low-profile Marx generator.

  2. Fuel Cell/Electrochemical Cell Voltage Monitor

    Science.gov (United States)

    Vasquez, Arturo

    2012-01-01

    A concept has been developed for a new fuel cell individual-cell-voltage monitor that can be directly connected to a multi-cell fuel cell stack for direct substack power provisioning. It can also provide voltage isolation for applications in high-voltage fuel cell stacks. The technology consists of basic modules, each with an 8- to 16-cell input electrical measurement connection port. For each basic module, a power input connection would be provided for direct connection to a sub-stack of fuel cells in series within the larger stack. This power connection would allow for module power to be available in the range of 9-15 volts DC. The relatively low voltage differences that the module would encounter from the input electrical measurement connection port, coupled with the fact that the module's operating power is supplied by the same substack voltage input (and so will be at similar voltage), provides for elimination of high-commonmode voltage issues within each module. Within each module, there would be options for analog-to-digital conversion and data transfer schemes. Each module would also include a data-output/communication port. Each of these ports would be required to be either non-electrical (e.g., optically isolated) or electrically isolated. This is necessary to account for the fact that the plurality of modules attached to the stack will normally be at a range of voltages approaching the full range of the fuel cell stack operating voltages. A communications/ data bus could interface with the several basic modules. Options have been identified for command inputs from the spacecraft vehicle controller, and for output-status/data feeds to the vehicle.

  3. Asphalt fume exposure levels in North American asphalt production and roofing manufacturing operations.

    Science.gov (United States)

    Axten, Charles W; Fayerweather, William E; Trumbore, David C; Mueller, Dennis J; Sampson, Arthur F

    2012-01-01

    This study extends by 8 years (1998-2005) a previous survey of asphalt fume exposures within North American asphalt processing and roofing product manufacturing workers. It focuses on characterizing personal, full-shift samples and seeks to address several limitations of the previous survey. Five major roofing manufacturers with established occupational health programs submitted workplace asphalt fume sampling results to a central repository for review and analysis. A certified industrial hygienist-led quality assurance team oversaw the data collection, consolidation, and analysis efforts. The analysis dataset consisted of 1261 personal exposure samples analyzed for total particulate (TP) and benzene soluble fraction (BSF) using existing NIOSH methods. For BSF, the survey's arithmetic (0.25 mg/m(3), SD = 0.62) and geometric (0.12 mg/m(3), GSD = 2.88) means indicate that the industry has sustained the control levels achieved in the late 1980s, early 1990s. Similar results were found for TP. The survey-wide summary statistics are consistent with other post-1990 multi-company exposure studies. Although these findings indicate that currently available controls are capable of achieving substantial (95%) compliance with the current threshold limit value in asphalt processing and inorganic shingle and roll plants, they also show that the majority of plants are not achieving this level of exposure control, and that exposures are significantly higher in plants making other product lines, particularly organic felt products. The current retrospective survey of existing company exposure data, like its predecessor, has several important limitations. These include lack of data on smaller manufacturers and on several commercially important product lines; insufficient information on the prevalence and effectiveness of engineering controls; no standard criteria by which to define and assess exposures in non-routine operations; and a paucity of exposure data collected as part of a

  4. Dynamic response characteristics analysis of the doubly-fed wind power system under grid voltage drop

    Science.gov (United States)

    Chen, Y.; Wang, J.; Wang, H. H.; Yang, L.; Chen, W.; Xu, Y. T.

    2016-08-01

    Double-fed induction generator (DFIG) is sensitive to the disturbances of grid, so the security and stability of the grid and the DFIG itself are under threat with the rapid increase of DFIG. Therefore, it is important to study dynamic response of the DFIG when voltage drop failure is happened in power system. In this paper, firstly, mathematical models and the control strategy about mechanical and electrical response processes is respectively introduced. Then through the analysis of response process, it is concluded that the dynamic response characteristics are related to voltage drop level, operating status of DFIG and control strategy adapted to rotor side. Last, the correctness of conclusion is validated by the simulation about mechanical and electrical response processes in different voltage levels drop and different DFIG output levels under DIgSILENT/PowerFactory software platform.

  5. Radiatively heated high voltage pyroelectric crystal pulser

    Energy Technology Data Exchange (ETDEWEB)

    Antolak, A.J., E-mail: antolak@sandia.gov [Sandia National Laboratories, Livermore, CA 94550 (United States); Chen, A.X. [Sandia National Laboratories, Livermore, CA 94550 (United States); Leung, K.-N. [Sandia National Laboratories, Livermore, CA 94550 (United States); Nuclear Engineering Department, University of California, Berkeley (United States); Morse, D.H.; Raber, T.N. [Sandia National Laboratories, Livermore, CA 94550 (United States)

    2014-01-21

    Thin lithium tantalate pyroelectric crystals in a multi-stage pulser were heated by quartz lamps during their charging phase to generate high voltage pulses. The charging voltage was determined empirically based on the measured breakdown voltage in air and verified by the induced breakdown voltage of an external high voltage power supply. A four-stage pyroelectric crystal device generated pulse discharges of up to 86 kV using both quartz lamps (radiative) and thermoelectric (conductive) heating. Approximately 50 mJ of electrical energy was harvested from the crystals when radiatively heated in air, and up to 720 mJ was produced when the crystals were submerged in a dielectric fluid. It is anticipated that joule-level pulse discharges could be obtained by employing additional stages and optimizing the heating configuration.

  6. The Operational Infrastructure of Secondary-Level CTE: Definition, Validation, and Application

    Science.gov (United States)

    Manley, R. Adam; Price, William T., Jr.

    2011-01-01

    The purpose of this study was to define and validate a set of criteria that would conceptualize the "big picture" operation of CTE within the state. Named the operational infrastructure of secondary CTE (OISCTE), these statements were defined as the basic, underlying framework of criteria that local, state, and university leaders in CTE…

  7. Low-voltage operation of ZrO2-gated n-type thin-film transistors based on a channel formed by hybrid phases of SnO and SnO2.

    Science.gov (United States)

    Chu, Hsin-Chueh; Shen, Yung-Shao; Hsieh, Ching-Heng; Huang, Jia-Hong; Wu, Yung-Hsien

    2015-07-22

    With SnO typically regarded as a p-type oxide semiconductor, an oxide semiconductor formed by hybrid phases of mainly SnO and a small amount of SnO2 with an average [O]/[Sn] ratio of 1.1 was investigated as a channel material for n-type thin-film transistors (TFTs). Furthermore, an appropriate number of oxygen vacancies were introduced into the oxide during annealing at 400 °C in ambient N2, making both SnO and SnO2 favorable for current conduction. By using high-κ ZrO2 with a capacitance equivalent thickness of 13.5 nm as the gate dielectric, the TFTs processed at 400 °C demonstrated a steep subthreshold swing (SS) of 0.21 V/dec, and this can be ascribed to the large gate capacitance along with a low interface trap density (Dit) value of 5.16 × 10(11) cm(-2) eV(-1). In addition, the TFTs exhibit a relatively high electron mobility of 7.84 cm(2)/V·s, high ON/OFF current ratios of up to 2.5 × 10(5), and a low gate leakage current at a low operation voltage of 3 V. The TFTs also prove its high reliability performance by showing negligible degradation of SS and threshold voltage (VT) against high field stress (-10 MV/cm). When 3% oxygen annealing is combined with a thinner channel thickness, TFTs with even higher ION/IOFF ratios exceeding 10(7) can also be obtained. With these promising characteristics, the overall performance of the TFTs displays competitive advantages compared with other n-type TFTs formed on binary or even some multicomponent oxide semiconductors and paves a promising and economic avenue to implement an n-type oxide semiconductor without doping for production-worthy TFT technology. Most importantly, when combined with the typical SnO-based p-type oxide semiconductor, it would usher in a new era in achieving high-performance complementary metal oxide semiconductor circuits by using the same SnO-based oxide semiconductor.

  8. Advances in high voltage power switching with GTOs

    Energy Technology Data Exchange (ETDEWEB)

    Podlesak, T.F. (US Army Electronic Technology and Devices Lab., Fort Monmouth, NJ (US)); McMurray, J.A. (Vitronics, Eatontown, NJ (US)); Carter, J.L.

    1990-12-01

    The control of high voltage at high power, particularly opening switches, has been difficult in the past. Using gate turnoff thyristors (GTOs) arranged in series enables large currents to be switched at high voltage. A high voltage opening switch has been successfully demonstrated in our laboratory. This switch uses GTOs in series and successfully operates at voltages higher than the rated voltage of the individual devices. It is believed that this is the first time this has been successfully demonstrated, in that GTOs have been operated in series before, but always in a manner as to not exceed the voltage capability of the individual devices. In short, the devices have not worked together, sharing the voltage, but one device has been operated using several backup devices. Of particular interest is how well the individual devices share the voltage applied to them. Equal voltage sharing between devices is absolutely essential, in order to not exceed the voltage rating of any of the devices in the series chain. This is accomplished at high (microsecond) switching speeds. Thus, the system is useful for high frequency applications as well as high power, making for a flexible circuit system element. This paper reports on this demonstration system that is rated at 5 KV and uses 1 KV devices. A larger 24 KV system is under design and will use 4.5 KV devices. In order to design the 24 KV switch, the safe operating area of the large devices must be known thoroughly.

  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. 基于矢量控制策略的永磁直驱风机在不同电压跌落程度下的故障特性分析%Fault Characteristic Analysis of Permanent Magnetic Synchronous Generator Based on Vector Control Strategy Under Different Levels of Voltage Drop

    Institute of Scientific and Technical Information of China (English)

    秦泽宁; 杨国生; 周泽昕; 王文焕; 王晓阳

    2016-01-01

    随着我国风电规模的不断扩大,永磁直驱风电机组获得广泛应用。首先,研究基于矢量控制策略的永磁直驱风机在不同电压跌落程度下的故障特性分析,在PSCAD/EMTDC中建立永磁直驱风机的网侧矢量控制和机侧零d轴电流控制搭配下的仿真模型;然后,分析当机端电压分别发生轻微跌落和严重跌落时,永磁直驱风机的故障电流特性和直流母线电压及有功、无功的变化规律;最后,针对限制短路故障电流和直流母线过电压,提出保障风机安全稳定运行的建议方法,为大规模永磁直驱式风力发电系统接入配电网提供技术支持。%With the continuous expansion of wind power, permanent magnetic synchronous generator (PMSG) has won a wide application. Firstly, this paper makes fault characteristic analysis of the PMSG based on vector control strategy under different levels of voltage drop. The simulation model of the permanent magnetic synchronous generator with grid-side vector control and machine-side zero d-axis current control in the PSCAD/EMTDC is built. Then, the fault current characteristic of PMSG and the change law of DC bus voltage and active and reactive power are studied when the terminal voltage drops slightly and drops severely. Finally, in order to limit the short-circuit fault current and DC bus over-voltage, recommended method for ensuring safe and stable operation of the wind turbine is proposed, which provides technical support for the large-scale direct-drive permanent magnetic wind power generation system’s access to distribution network.

  11. FGMOS Based Voltage-Controlled Grounded Resistor

    Directory of Open Access Journals (Sweden)

    R. Pandey

    2010-09-01

    Full Text Available This paper proposes a new floating gate MOSFET (FGMOS based voltage-controlled grounded resistor. In the proposed circuit FGMOS operating in the ohmic region is linearized by another conventional MOSFET operating in the saturation region. The major advantages of FGMOS based voltage-controlled grounded resistor (FGVCGR are simplicity, low total harmonic distortion (THD, and low power consumption. A simple application of this FGVCGR as a tunable high-pass filter is also suggested. The proposed circuits operate at the supply voltages of +/-0.75 V. The circuits are designed and simulated using SPICE in 0.25-µm CMOS technology. The simulation results of FGVCGR demonstrate a THD of 0.28% for the input signal 0.32 Vpp at 45 kHz, and a maximum power consumption of 254 µW.

  12. Lateral current effects on the voltage distribution in the emitter of solar cells under concentrated sunlight

    Energy Technology Data Exchange (ETDEWEB)

    Morales-Acevedo, Arturo [CINVESTAV-IPN, Electrical Engineering Department, Avenida IPN No. 2508, 07360 Mexico, DF (Mexico)

    2009-04-15

    The design of the grid contact in silicon solar cells is one of the most important steps for the optimization and fabrication of these energy conversion devices. The voltage drop due to the lateral flow of current towards the grid fingers can be a limiting factor causing the reduction of conversion efficiency. For low current levels this voltage drop can be made small, for typical values of sheet resistance in the emitter, but for solar cells made to operate at high sun concentrations this efficiency loss can be important, unless there is a clear vision of the current and voltage distribution so that the emitter and grid design can be improved. Hence, it is important to establish and solve the current and voltage distribution equations for solar cells with a grid contact. In this work, first these equations are established and then they are solved in order to show the effects that the lateral current flow in the emitter cause on the voltage distribution, particularly at high illumination levels. In addition, it will be shown that the open circuit voltage is significantly reduced due to the lateral current flow as compared to the value predicted from a simple equivalent circuit with a lumped resistance model. (author)

  13. Voltage stability and controllability indices for multimachine power systems

    Energy Technology Data Exchange (ETDEWEB)

    Vournas, C.D. [National Technical Univ., Athens (Greece). Electrical Energy Systems Lab.

    1995-08-01

    This paper presents a voltage stability index (VSI) and a voltage controllability index (VCI), related to the eigenvalues of mxm matrices in a multimachine power system made up of m synchronous generators and a number of infinite buses. System loads can have an arbitrary voltage sensitivity described by generalized voltage exponents. These nonlinear loads are linearized around an operating point and incorporated into a modified admittance matrix, which is subsequently reduced to the generator terminals using an efficient algorithm and sparsity techniques. The indices proposed are tested in a practical system and it is demonstrated that they provide a timely warning during a sequence of events leading to voltage collapse.

  14. Exploring Three-Phase Systems and Synchronous Motors: A Low-Voltage and Low-Cost Experiment at the Sophomore Level

    Science.gov (United States)

    Schubert, T. F., Jr.; Jacobitz, F. G.; Kim, E. M.

    2011-01-01

    In order to meet changing curricular and societal needs, a three-phase system and synchronous motor laboratory experience for sophomore-level students in a wide variety of engineering majors was designed, implemented, and assessed. The experiment is unusual in its early placement in the curriculum, and in that it focuses primarily on basic…

  15. The levels of forming at students of general school operating mobility as executive component of arbitrary management of moving activity.

    Directory of Open Access Journals (Sweden)

    Artyushenko A.A.

    2011-03-01

    Full Text Available The aim of researches is to determine concept «Personality mobility» in the light of pictures of arbitrary management conduct and activity of man In the article is considered question of diagnostics of forming operating mobility for the students of general school as activity of constituent of arbitrary management. It is certain four levels of formed operating mobility for lower boys, for teenagers and for senior pupils. It is well-proven that for period of studies at general school the indexes of operating mobility of students are not change substantially.

  16. Low voltage electron beam accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ochi, Masafumi [Iwasaki Electric Co., Ltd., Tokyo (Japan)

    2003-02-01

    Widely used electron accelerators in industries are the electron beams with acceleration voltage at 300 kV or less. The typical examples are shown on manufactures in Japan, equipment configuration, operation, determination of process parameters, and basic maintenance requirement of the electron beam processors. New electron beam processors with acceleration voltage around 100 kV were introduced maintaining the relatively high dose speed capability of around 10,000 kGy x mpm at production by ESI (Energy Science Inc. USA, Iwasaki Electric Group). The application field like printing and coating for packaging requires treating thickness of 30 micron or less. It does not require high voltage over 110 kV. Also recently developed is a miniature bulb type electron beam tube with energy less than 60 kV. The new application area for this new electron beam tube is being searched. The drive force of this technology to spread in the industries would be further development of new application, process and market as well as the price reduction of the equipment, upon which further acknowledgement and acceptance of the technology to societies and industries would entirely depend. (Y. Tanaka)

  17. The Combination of Postponement Operations in a Supply Chain Network with Multi-level Product Differentiations

    Directory of Open Access Journals (Sweden)

    Ying Lu

    2013-12-01

    Full Text Available To study the problem about the optimal combination of postponement operations in the context of supply chain network, a decision-making model is developed. In the model two kinds of product differentiations and three types of postponement operations are considered. Then a procedure for solving this model is proposed. By using a numerical example, we analyze the effect of cost structure on the decision about postponement operations. The results show that if customizing cost is high, no customizing operation should be adopted, if the subassembly-related costs are large assembling directly the components is more sensible, as well as if lead time is tight and penalty cost is high, only manufacturing postponement should be adopted

  18. 47 CFR 11.54 - EAS operation during a National Level emergency.

    Science.gov (United States)

    2010-10-01

    ... licensees and DBS providers may choose their two EAS sources, one of which must be a PEP station. (2... operate under the procedures in the National Control Point Procedures. (13) The time of receipt of the EAN...

  19. Mean sound level in operation rooms in a referral hospital: a brief report

    Directory of Open Access Journals (Sweden)

    Ahmad Joneidi Jafari

    2014-02-01

    Conclusion: Overall total noise dose during all types of surgeries was measured as twice of permitted dose and also orthopedic and general operation rooms experience brief periods of noise exposure in excess.

  20. Enterprise Level Status and Control of Multi-Satellite Operations Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The objective of this project is to take information from multiple operational environments and securely deliver it in a graphically useful manner to the end user....