WorldWideScience

Sample records for resistance short-circuit current

  1. Shapeable short circuit resistant capacitor

    Science.gov (United States)

    Taylor, Ralph S.; Myers, John D.; Baney, William J.

    2015-10-06

    A ceramic short circuit resistant capacitor that is bendable and/or shapeable to provide a multiple layer capacitor that is extremely compact and amenable to desirable geometries. The capacitor that exhibits a benign failure mode in which a multitude of discrete failure events result in a gradual loss of capacitance. Each event is a localized event in which localized heating causes an adjacent portion of one or both of the electrodes to vaporize, physically cleaning away electrode material from the failure site. A first metal electrode, a second metal electrode, and a ceramic dielectric layer between the electrodes are thin enough to be formed in a serpentine-arrangement with gaps between the first electrode and the second electrode that allow venting of vaporized electrode material in the event of a benign failure.

  2. Worst Asymmetrical Short-Circuit Current

    DEFF Research Database (Denmark)

    Arana Aristi, Iván; Holmstrøm, O; Grastrup, L

    2010-01-01

    In a typical power plant, the production scenario and the short-circuit time were found for the worst asymmetrical short-circuit current. Then, a sensitivity analysis on the missing generator values was realized in order to minimize the uncertainty of the results. Afterward the worst asymmetrical...

  3. Effect of variation of I{sub 01}/I{sub 02} on short-circuit current and fill factor of a real solar cell having resistive and current leakage losses

    Energy Technology Data Exchange (ETDEWEB)

    Dadu, M.; Kapoor, A.; Tripathi, K.N. [Department of Electronic Sciences, University of Delhi, South Campus, Benito Juarez Road, -110021 New Delhi (India)

    2001-11-01

    We analyze the effect of variation of I{sub 01}/I{sub 02} on short-circuit current and the fill factor of a solar cell having resistive and current leakage losses. This analysis is particularly important for the polycrystalline solar cells, where higher values of I{sub 02} and hence lower values of I{sub 01}/I{sub 02} can be expected due to the space charge regions associated with the grain boundaries. Also in polycrystalline solar cells, we cannot ignore the effect of series and shunt resistances. It is observed that the value of fill factor depends on R{sub s}, R{sub sh} and I{sub 01}/I{sub 02}, while the value of I{sub sc} depends only on R{sub s} and I{sub 01}/I{sub 02}.

  4. Short-Circuit Current Analysis for DFIG Wind Farm Considering the Action of a Crowbar

    Directory of Open Access Journals (Sweden)

    Yan Hong Yuan

    2018-02-01

    Full Text Available With the increasing capacity of wind farms integrated into the power grid, the short-circuit current analysis for wind farms becomes more and more important. Since the wind turbine is usually integrated into the power grid via power electronic devices, the “crowbar” is installed in the wind turbine to protect the power electronic devices and to improve the fault ride through capability. The impact of the crowbar has to be considered during the short-circuit current analysis for the wind farm. In order to fully analyze the short-circuit current characteristics of a wind farm, the short-circuit currents for a doubly-fed induction generator (DFIG wind turbine under symmetrical and asymmetrical faults considering the crowbar action characteristic are derived firstly. Then the action situation of the crowbar of a DFIG wind turbine is studied and the action area curve is obtained. Taking the crowbar action, or not, as the grouping criterion, wind turbines in the wind farm are divided into two groups, and the wind farm is aggregated into two equivalent wind turbines. Using the equivalent model, the short-circuit current of a wind farm can be calculated accurately. Finally, simulations are performed in MATLAB/Simulink which is the commercial math software produced by the MathWorks company in Natick, Massachusetts, the United States to verify the proposed short-circuit current calculation method for the DFIG wind farm.

  5. Short-Circuit Current Analysis for DFIG Wind Farm Considering the Action of a Crowbar

    OpenAIRE

    Yan Hong Yuan; Feng Wu

    2018-01-01

    With the increasing capacity of wind farms integrated into the power grid, the short-circuit current analysis for wind farms becomes more and more important. Since the wind turbine is usually integrated into the power grid via power electronic devices, the “crowbar” is installed in the wind turbine to protect the power electronic devices and to improve the fault ride through capability. The impact of the crowbar has to be considered during the short-circuit current analysis for the wind farm....

  6. Influence of wavelength on transient short-circuit current in polycrystalline silicon solar cells

    International Nuclear Information System (INIS)

    Ba, B.; Kane, M.

    1993-10-01

    The influence of the wavelength of a monochromatic illumination on transient short-circuit current in an n/p polycrystalline silicon part solar cell junction is investigated. A wavelength dependence in the initial part of the current decay is observed in the case of cells with moderate grain boundary effects. This influence is attenuated in polycrystalline cells with strong grain boundary activity. (author). 10 refs, 6 figs

  7. Mathematical Model of Electromagnetic Transient for Superconducting Short-Circuit Current Limiter

    Directory of Open Access Journals (Sweden)

    Manusov V.Z.

    2017-08-01

    Full Text Available At present on the basis of significant achievements in the field of high-temperature superconductivity more and more applications of this phenomenon appear in the electric power industry, in particular superconducting current limiters. To investigate current limitation process in electrical networks containing superconducting current limiter it is extremely important to evaluate the electrodynamic and thermal effects of the short-circuit current at any time. The existing superconducting current limiters mathematical models don't consider the inertia of the device transition from the superconducting state to the conducting one. It is necessary to develop the mathematical model for the electromagnetic transient process that can adequately simulate the superconducting current limiter at any time point, taking into account its parameters in the normal and emergency modes and also to describe these parameters dynamics during the process of current limitation. The proposed mathematical model allows to simulate the changing inertia of the superconducting current limiter inductive reactance, to analytically describe the electromagnetic transient process, and also to evaluate the electrodynamic and thermal effects of short-circuit current in networks with superconducting current limiter. The important feature of the mathematical model is the consideration of the increase rate (inertia of the inductive reactance with respect to the external network. Also the model allows taking into account the initial and final values of the inductance of a superconducting current limiter before and after the end of the electromagnetic transient respectively.

  8. Modeling the short-circuit current density of polymer solar cells based on P3HT:PCBM blend

    Energy Technology Data Exchange (ETDEWEB)

    Monestier, Florent; Simon, Jean-Jacques; Torchio, Philippe; Escoubas, Ludovic; Flory, Francois [Institut FRESNEL, UMR-CNRS 6133, Domaine Universitaire de St-Jerome, 13397 Marseille Cedex 20 (France); Bailly, Sandrine; de Bettignies, Remi; Guillerez, Stephane [INES CEA/DRT/LITEN/DTS/LCS, BP 332 50, av. du lac Leman 73370, Le Bourget du lac (France); Defranoux, Christophe [SOPRA-SA, Bois Colombes (France)

    2007-03-06

    We have investigated the short-circuit current density of organic solar cells based on poly (3-hexylthiophene)(P3HT)/6,6-phenyl C61-butyric acid methyl ester (PCBM) blend. In order to model charge collection efficiencies with respect to short circuit density in such blends, a full optical modeling of the cell is performed. From the distribution of the electromagnetic field, we compute the rate of exciton generation. This exciton generation rate is used as input in the transport equations of holes and electrons. Charge densities at steady state are obtained as solutions are used for computing short-circuit current densities generated in the cell. The dependence of short-circuit current densities versus the thickness of the blend is analyzed and compared with our experimental data and with data extracted from the literature. (author)

  9. Design and optimization of LCL-VSC grid-tied converter having short circuit fault current limiting ability

    Science.gov (United States)

    Liu, Mengqi; Liu, Haijun; Wang, Zhikai

    2017-01-01

    Traditional LCL grid-tied converters haven't the ability to limit the short-circuit fault current and only remove grid-connected converter using the breaker. However, the VSC converters become uncontrollable after the short circuit fault cutting off and the power switches may be damaged if the circuit breaker removes slowly. Compared to the filter function of the LCL passive components in traditional VSC converters, the novel LCL-VSC converter has the ability of limiting the short circuit fault current using the reasonable designed LCL parameters. In this paper the mathematical model of the LCL converter is established and the characteristics of the short circuit fault current generated by the ac side and dc side are analyzed. Thus one design and optimization scheme of the reasonable LCL passive parameter is proposed for the LCL-VSC converter having short circuit fault current limiting ability. In addition to ensuring the LCL passive components filtering the high-frequency harmonic, this scheme also considers the impedance characteristics to limit the fault current of AC and DC short circuit fault respectively flowing through the power switch no more than the maximum allowable operating current, in order to make the LCL converter working continuously. Finally, the 200kW simulation system is set up to prove the validity and feasibility of the theoretical analysis using the proposed design and optimization scheme.

  10. Technical Study on Improvement of Endurance Capability of Limit Short-circuit Current of Charge Control SMART Meter

    Science.gov (United States)

    Li, W. W.; Du, Z. Z.; Yuan, R. m.; Xiong, D. Z.; Shi, E. W.; Lu, G. N.; Dai, Z. Y.; Chen, X. Q.; Jiang, Z. Y.; Lv, Y. G.

    2017-10-01

    Smart meter represents the development direction of energy-saving smart grid in the future. The load switch, one of the core parts of smart meter, should be of high reliability, safety and endurance capability of limit short-circuit current. For this reason, this paper discusses the quick simulation of relationship between attraction and counterforce of load switch without iteration, establishes dual response surface model of attraction and counterforce and optimizes the design scheme of load switch for charge control smart meter, thus increasing electromagnetic attraction and spring counterforce. In this way, this paper puts forward a method to improve the withstand capacity of limit short-circuit current.

  11. Solar Cell Short Circuit Current Errors and Uncertainties During High Altitude Calibrations

    Science.gov (United States)

    Snyder, David D.

    2012-01-01

    High altitude balloon based facilities can make solar cell calibration measurements above 99.5% of the atmosphere to use for adjusting laboratory solar simulators. While close to on-orbit illumination, the small attenuation to the spectra may result in under measurements of solar cell parameters. Variations of stratospheric weather, may produce flight-to-flight measurement variations. To support the NSCAP effort, this work quantifies some of the effects on solar cell short circuit current (Isc) measurements on triple junction sub-cells. This work looks at several types of high altitude methods, direct high altitude meas urements near 120 kft, and lower stratospheric Langley plots from aircraft. It also looks at Langley extrapolation from altitudes above most of the ozone, for potential small balloon payloads. A convolution of the sub-cell spectral response with the standard solar spectrum modified by several absorption processes is used to determine the relative change from AMO, lscllsc(AMO). Rayleigh scattering, molecular scatterin g from uniformly mixed gases, Ozone, and water vapor, are included in this analysis. A range of atmosph eric pressures are examined, from 0. 05 to 0.25 Atm to cover the range of atmospheric altitudes where solar cell calibrations a reperformed. Generally these errors and uncertainties are less than 0.2%

  12. Detection of Short-Circuit Location in Distribution Mains Line within Functions of Micro-Processor Current Protection

    Directory of Open Access Journals (Sweden)

    F. A. Romaniuk

    2010-01-01

    Full Text Available The paper considers a method for improvement of micro-processor current protection lines that permits to expand a zone of instantaneous short-circuit cut-off  and decrease a number of discriminating elements. In order to reach this purpose the paper proposes additionally to determine a distance up to the short circuit location within functions of the lines concerned. A distance principle for determination of a distance up to the damage place can be laid down in the basis for сalculation of short-circuit location while using an algorithm of orthogonal components or a 3-counting algorithm. The first mentioned algorithm is characterized by higher accuracy but it is sensitive to frequency changes. The 3-counting algorithm is practically insensitive to frequency changes but it is less accurate. Altogether each of the considered algorithms is operational and ensures obtaining of the required information for efficient realization of functions for detection of damage location.The given propositions can be used while developing algorithms for operation of micro-processor current directed protections of distribution mains lines.

  13. Simultaneous enhancement of open-circuit voltage, short-circuit current density, and fill factor in polymer solar cells

    Energy Technology Data Exchange (ETDEWEB)

    He, Zhicai; Zhong, Chengmei; Wu, Hongbin; Su, Shijian; Cao, Yong [Institute of Polymer Optoelectronic Materials and Devices, State Key Laboratory of Luminescent Materials and Devices, South China University of Technology, Guangzhou 510640 (China); Huang, Xun; Chen, Liwei [Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences, 398 Ruoshui Road, Suzhou Industrial Park, Suzhou 215123 (China); Wong, Wai-Yeung [Institute of Molecular Functional Materials (Areas of Excellence Scheme, University Grants Committee, Hong Kong) and Department of Chemistry and Centre for Advanced Luminescence Materials, Hong Kong Baptist University, Waterloo Road, Hong Kong (China)

    2011-10-25

    Simultaneous enhancement of open-circuit voltage, short-circuit current density, and fill factor in highly efficient polymer solar cells by incorporating an alcohol/water-soluble conjugated polymer as cathode interlayer is domonstrated. When combined with a low-bandgap polymer PTB7 as the electron donor material, the power efficiency of the devices is improved to certified 8.370%. Due to drastic improvement in efficiency and easy utilization, this method opens new opportunities for PSCs from various material systems to improve towards 10% efficiency. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  14. Enhancement of short-circuit current density in polymer bulk heterojunction solar cells comprising plasmonic silver nanowires

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yuzhao; Lin, Xiaofeng; Ou, Jiemei; Chen, Xudong, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [Key Laboratory for Polymeric Composite and Functional Materials of Ministry of Education of China, Sun Yat-sen University, Guangzhou 510275 (China); Qing, Jian; Zhong, Zhenfeng; Zhou, Xiang, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn; Chen, Yujie, E-mail: cescxd@mail.sysu.edu.cn, E-mail: stszx@mail.sysu.edu.cn, E-mail: chenyj69@mail.sysu.edu.cn [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Hu, Chenglong [Key Laboratory of Optoelectronic Chemical Materials and Devices of Ministry of Education, Jianghan University, Wuhan 430056 (China)

    2014-03-24

    We demonstrate that the influence of plasmonic effects based on silver nanowires (Ag NWs) on the characteristics of polymer solar cells (PSCs). The solution-processed Ag NWs are situated at the interface of anode buffer layer and active layer, which could enhance the performance especially the photocurrent of PSCs by scattering, localized surface plasmon resonance, and surface plasmon polaritons. Plasmonic effects are confirmed by the enhancement of extinction spectra, external quantum efficiency, and steady state photoluminescence. Consequently, the short-circuit current density (J{sub sc}) and power conversion efficiency enhance about 24% and 18%, respectively, under AM1.5 illumination when Ag NWs plasmonic nanostructure incorporated into PSCs.

  15. Effect of notch depth of modified current collector on internal-short-circuit mitigation for lithium-ion battery

    Science.gov (United States)

    Wang, Meng; Noelle, Daniel J.; Shi, Yang; Le, Anh V.; Qiao, Yu

    2018-01-01

    Formation of internal short circuit (ISC) may result in catastrophic thermal runaway of lithium-ion battery (LIB). Among LIB cell components, direct contact between cathode and anode current collectors is most critical to the ISC behavior, yet is still relatively uninvestigated. In the current study, we analyze the effect of heterogeneity of current collector on the temperature increase of LIB cells subjected to mechanical abuse. The cathode current collector is modified by surface notches, so that it becomes effectively brittle and the ISC site can be isolated. Results from impact tests on LIB cells with modified current collectors suggest that their temperature increase can be negligible. The critical parameters include the failure strain and the failure work of modified current collector, both of which are related to the notch depth.

  16. Identification of Magnetizing Inrush and Internal Short-Circuit Fault Current in V/x-Type Traction Transformer

    Directory of Open Access Journals (Sweden)

    Y. H. Li

    2013-01-01

    Full Text Available This paper deals with the fault diagnosis methodology for the V/x-type traction transformer in railway passenger-dedicated lines. A kind of the protection methodology to combine empirical mode decomposition (EMD, energy weight, and information entropy is proposed. This method can sensitively reflect the dynamic information changes of traction transformer differential current, so it can not only effectively identify internal short-circuit fault current from magnetizing inrush but also better identify fault current accompanied with magnetizing inrush. In this method, the differential current is decomposed by EMD and the energy weight of each intrinsic mode function (IMF is calculated, and the feature vector of the fault pattern recognition is obtained by constructing IMF energy entropy. The field-measured data illustrate that the new method not only has the advantages of high sensitivity, faster identification speed, and clear concept but also is available for the diagnosis of the complicated dynamic system.

  17. Spotting the earth connection and short circuits between the electric conductors, using D.C. bridges for resistance measurements

    Science.gov (United States)

    Popa, I.; Popa, G. N.; Deaconu, S. I.; Iagăr, A.

    2015-06-01

    The paper establishes the necessary connections meant to spot the earth connections and short circuits between the conductors of a power line, using the DC bridges meant for measuring resistances between conductors at the ends of the power line. Since it is a relative method, it imposes an exact knowledge of the faulty power line setting. For values of the resistances measured between the conductors of the power line having over 1Ω at one end, the measurement will be carried out with a Wheatstone bridge, and for values below 1Ω with a Thomson bridge. In order to accurately determine the place of the fault, it measured the distances from the end of the line up to the fault and then we performed a correction calculation for this distance.

  18. Analysis of the impact of connecting a larger number of small hydroelectric power plants to the short-circuit currents values and relay protection system of distribution network

    Directory of Open Access Journals (Sweden)

    Sučević Nikola

    2017-01-01

    Full Text Available In this paper the influence of a large number of small hydro power plants on the short-circuit currents is analysed, as well as the operation of the relay protection system within the real distribution network in Serbia. The necessary modification of the existing protection functions, as well as the implementation of the new proposed protection functions, are presented and discussed. Network modeling and analysis are performed using the program tool DIgSILENT PowerFactory.

  19. Controlled Conjugated Backbone Twisting for an Increased Open-Circuit Voltage while Having a High Short-Circuit Current in Poly(hexylthiophene) Derivatives

    KAUST Repository

    Ko, Sangwon

    2012-03-21

    Conjugated polymers with nearly planar backbones have been the most commonly investigated materials for organic-based electronic devices. More twisted polymer backbones have been shown to achieve larger open-circuit voltages in solar cells, though with decreased short-circuit current densities. We systematically impose twists within a family of poly(hexylthiophene)s and examine their influence on the performance of polymer:fullerene bulk heterojunction (BHJ) solar cells. A simple chemical modification concerning the number and placement of alkyl side chains along the conjugated backbone is used to control the degree of backbone twisting. Density functional theory calculations were carried out on a series of oligothiophene structures to provide insights on how the sterically induced twisting influences the geometric, electronic, and optical properties. Grazing incidence X-ray scattering measurements were performed to investigate how the thin-film packing structure was affected. The open-circuit voltage and charge-transfer state energy of the polymer:fullerene BHJ solar cells increased substantially with the degree of twist induced within the conjugated backbone-due to an increase in the polymer ionization potential-while the short-circuit current decreased as a result of a larger optical gap and lower hole mobility. A controlled, moderate degree of twist along the poly(3,4-dihexyl-2,2′:5′,2′′- terthiophene) (PDHTT) conjugated backbone led to a 19% enhancement in the open-circuit voltage (0.735 V) vs poly(3-hexylthiophene)-based devices, while similar short-circuit current densities, fill factors, and hole-carrier mobilities were maintained. These factors resulted in a power conversion efficiency of 4.2% for a PDHTT:[6,6]-phenyl-C 71-butyric acid methyl ester (PC 71BM) blend solar cell without thermal annealing. This simple approach reveals a molecular design avenue to increase open-circuit voltage while retaining the short-circuit current. © 2012 American

  20. Tunnel FinFET CMOS inverter with very low short-circuit current for ultralow-power Internet of Things application

    Science.gov (United States)

    Morita, Yukinori; Fukuda, Koichi; Liu, Yongxun; Mori, Takahiro; Mizubayashi, Wataru; O'uchi, Shin-ichi; Fuketa, Hiroshi; Otsuka, Shintaro; Migita, Shinji; Masahara, Meishoku; Endo, Kazuhiko; Ota, Hiroyuki; Matsukawa, Takashi

    2017-04-01

    We have demonstrated the operation of a CMOS inverter consisting of Si tunnel FinFETs. Both p- and n-type tunnel FinFETs are successfully fabricated and operated on the same SOI wafer. The current mismatch between p- and n-type tunnel FETs is compensated by tuning the number of fin channels. Very low short-circuit current and clear voltage input-output characteristics are obtained. The thin epitaxial channel in the tunnel FinFETs effectively increases the drain current and accordingly reduces the drain capacitance, which could help high-performance tunnel FET CMOS inverter operation.

  1. Utilization of symmetrical components in a communication-assisted protection scheme for radial MV feeders with variable or reduced short-circuit currents

    DEFF Research Database (Denmark)

    Ciontea, Catalin-Iosif; Bak, Claus Leth; Blaabjerg, Frede

    2017-01-01

    -circuit power and reduced short-circuit currents compared to the OverCurrent protection. In addition, coordination of the relays that use the proposed algorithm does not require a prior knowledge of the load or fault currents. The setting procedure of the relays that use the new protection algorithm......Distribution networks are evolving toward the vision of microgrids, which are defined as power systems that contain both loads and Distributed Energy Resources and operate in a grid-connected or islanded mode. Correct operation of the OverCurrent protection is compromised in a typical microgrid...... because the fault current is significantly lower in the islanded mode compared to the grid-connected mode and consequently a single set of settings for the OC relays is not sufficient. This paper propose a communication-assisted protection scheme that is able to operate correctly in a radial Medium...

  2. External short circuit performance of Graphite-LiNi1/3Co1/3Mn1/3O2 and Graphite-LiNi0.8Co0.15Al0.05O2 cells at different external resistances

    Science.gov (United States)

    Kriston, Akos; Pfrang, Andreas; Döring, Harry; Fritsch, Benjamin; Ruiz, Vanesa; Adanouj, Ibtissam; Kosmidou, Theodora; Ungeheuer, Jürgen; Boon-Brett, Lois

    2017-09-01

    This study aims at analyzing the response of Li-ion cells and at identifying the hazards and governing phenomena from hard to soft external short circuit conditions. 10 Ah pouch cells and 4.5 mAh coin cells were short circuited while synchronized current, potential and temperature signals, audio, IR and visual video recordings were registered. The anode, cathode and separator harvested from the cells were characterized by Scanning Electron Microscopy, micro X-ray Computed Tomography and 3D-profilometry. The complex short circuit behavior obtained can be described by 3 regions: In the first region 274C-rate is observed which is mainly governed by the cell's double and diffusion layer discharge. In the second region, the current drops significantly to 50-60C-rate where mass transport becomes the current limiting factor. The maximum temperature (77-121 °C) is reached and cell rupture, venting and electrolyte leakage may occur. In the final, third region the current decline continues due to the decaying electromotive force. The normalized external/internal resistance ratio is found to be the main influential factor on current and hazards rather than the external resistance or the capacity of the cell. The implications on the relevance and fitness-for-purpose of external short circuit test in standards are outlined.

  3. Improvement of Short-Circuit Current Density in Dye-Sensitized Solar Cells Using Sputtered Nanocolumnar TiO2 Compact Layer

    Directory of Open Access Journals (Sweden)

    Lung-Chien Chen

    2010-01-01

    Full Text Available The effect of a nanocolumnar TiO2 compact layer in dye-sensitized solar cells (DSSCs was examined. Such a compact layer was sputtered on a glass substrate with an indium tin oxide (ITO film using TiO2 powder as the raw material, with a thickness of ~100 nm. The compact layer improved the short-circuit current density and the efficiency of conversion of solar energy to electricity by the DSSC by 53.37% and 59.34%, yielding values of 27.33 mA/cm2 and 9.21%, respectively. The performance was attributed to the effective electron pathways in the TiO2 compact layer, which reduced the back reaction by preventing direct contact between the redox electrolyte and the conductive substrate.

  4. Improvement of Short-Circuit Current Density in p-Ni1−xO:Li/n-Si Heterojunction Solar Cells by Wet Chemical Etching

    Directory of Open Access Journals (Sweden)

    Feng-Hao Hsu

    2014-01-01

    Full Text Available This study confirms that the surface texturation of window layer (Al-Y codoped ZnO etched by diluted HCl effectively increases conversion efficiency of p-Ni1−xO:Li/n-Si heterojunction solar cells. The results show that the short circuit current density (Jsc of cell etched at 10 s increases about 8.5% compared to unetched cell, which also corresponds to the increase of efficient photoelectric conversion in NIR region as shown in external quantum efficiency spectra. It is attributed to the increase of light transmittance of AZOY thin films in the NIR region and the effective light path of the NIR wavelength, which results in increasing of light absorption in the base layer.

  5. Tin Whisker Electrical Short Circuit Characteristics Part 2

    Science.gov (United States)

    Courey, Karim J.; Asfour, Shihab S.; Bayliss, Jon A.; Ludwib, Lawrence L.; Zapata, Maria C.

    2007-01-01

    Existing risk simulations make the assumption that when a free tin whisker has bridged two adjacent exposed electrical conductors, the result is an electrical short circuit. This conservative assumption is made because shorting is a random event that has a currently unknown probability associated with it. Due to contact resistance electrical shorts may not occur at lower voltage levels. In this experiment, we study the effect of varying voltage on the breakdown of the contact resistance which leads to a short circuit. From this data we can estimate the probability of an electrical short, as a function of voltage, given that a free tin whisker has bridged two adjacent exposed electrical conductors. In addition, three tin whiskers grown from the same Space Shuttle Orbiter card guide used in the aforementioned experiment were cross-sectioned and studied using a focused ion beam (FIB).

  6. Estimating the short-circuit impedance

    DEFF Research Database (Denmark)

    Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

    1997-01-01

    and current are derived each period, and the short-circuit impedance is estimated from variations in these components created by load changes in the grid. Due to the noisy and dynamic grid with high harmonic distortion it is necessary to threat the calculated values statistical. This is done recursively...... through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...

  7. An Icepak-PSpice Co-Simulation Method to Study the Impact of Bond Wires Fatigue on the Current and Temperature Distribution of IGBT Modules under Short-Circuit

    DEFF Research Database (Denmark)

    Wu, Rui; Iannuzzo, Francesco; Wang, Huai

    2014-01-01

    Bond wires fatigue is one of the dominant failure mechanisms of IGBT modules. Prior-art research mainly focuses on its impact on the end-of-life failure, while its effect on the short-circuit capability of IGBT modules is still an open issue. This paper proposes a new electro-thermal simulation...... approach enabling analyze the impact of the bond wires fatigue on the current and temperature distribution on IGBT chip surface under short-circuit. It is based on an Icepack-PSpice co-simulation by taking the advantage of both a finite element thermal model and an advanced PSpice-based multi-cell IGBT...

  8. Analysis of Limiting Measures of Three-phase Short-circuit Current of 500kV Intensive Receiving-end Power Grid in the Early Stage of UHV Construction

    Directory of Open Access Journals (Sweden)

    Zhang Xiao Hang

    2016-01-01

    Full Text Available This paper took the intensive receiving-end power grid as the research object and analysed the problems of three-phase short-circuit current over-limited of 500kV intensive power grid in the early stage of UHV construction. Firstly, this paper analysed the influence factors of the short-circuit current based on self-impedance analysis model of two-port network theory and the equivalent model of UHV power grid. Then, the applicable current-limiting measures were put forward. Finally, this paper proposed one scheme to solve the problems of three-phase short-circuit current over-limited of 500kV buses in one practical receiving-end power grid and verified the feasibility of this scheme from three different aspects. Aiming at the over-limited influential factors, the applicable current-limiting measures can be taken as follows: separating the 500kV bus at UHV substation, lapping the lines outside the substation and decentralizing the power supplies. The proposed measures can effectively solve the problems of short-circuit current over-limited in the early stage of UHV construction and provide reference for other power grid.

  9. Effects of tetrodotoxin and ion replacements on the short-circuit current induced by Escherichiacoli heat stable enterotoxin across small intestine of the gerbil (Gerbillus cheesmani

    Directory of Open Access Journals (Sweden)

    Fawzia Yaqoub Al-Balool

    2004-03-01

    Full Text Available The effects of mucosally added Escherichia coli heat stable enterotoxin (STa 30 ng ml-1 on the basal short-circuit current (Isc in µA cm-2 across stripped and unstripped sheets of jejuna and ilea taken from fed, starved (4 days, water ad lib and undernourished (50% control food intake for 21 days gerbil (Gerbillus cheesmani were investigated. The effect of neurotoxin tetrodotoxin (TTX 10 µM and the effects of replacing chloride by gluconate or the effects of removing bicarbonate from bathing buffers on the maximum increase in Isc induced by STa were also investigated. The maximum increase in Isc which resulted from the addition of STa were significantly higher in jejuna and ilea taken from starved and undernourished gerbils when compared with the fed control both using stripped and unstripped sheets. In the two regions of the small intestine taken from fed and starved animals TTX reduced the maximum increase in Isc induced by STa across unstripped sheets only. Moreover in jejuna and ilea taken from undernourished gerbils TTX reduced significantly the maximum increase in Isc induced by STa across stripped and unstripped sheets. Replacing chloride by gluconate decreased the maximum increase in Isc induced by STa across jejuna and ilea taken from undernourished gerbils only. Removing bicarbonates from bathing buffer decreased the maximum increase in Isc across the jejuna and ilea taken from starved and undernourished gerbils.

  10. Bumetanide increases Cl--dependent short-circuit current in late distal colon: Evidence for the presence of active electrogenic Cl- absorption.

    Science.gov (United States)

    Tang, Lieqi; Fang, Xiefan; Winesett, Steven P; Cheng, Catherine Y; Binder, Henry J; Rivkees, Scott A; Cheng, Sam X

    2017-01-01

    Mammalian colonic epithelia consist of cells that are capable of both absorbing and secreting Cl-. The present studies employing Ussing chamber technique identified two opposing short-circuit current (Isc) responses to basolateral bumetanide in rat distal colon. Apart from the transepithelial Cl--secretory Isc in early distal colon that was inhibited by bumetanide, bumetanide also stimulated Isc in late distal colon that had not previously been identified. Since bumetanide inhibits basolateral Na+-K+-2Cl- cotransporter (NKCC) in crypt cells and basolateral K+-Cl- cotransporter (KCC) in surface epithelium, we proposed this stimulatory Isc could represent a KCC-mediated Cl- absorptive current. In support of this hypothesis, ion substitution experiments established Cl- dependency of this absorptive Isc and transport inhibitor studies demonstrated the involvement of an apical Cl- conductance. Current distribution and RNA sequencing analyses revealed that this Cl- absorptive Isc is closely associated with epithelial Na+ channel (ENaC) but is not dependent on ENaC activity. Thus, inhibition of ENaC by 10 μM amiloride or benzamil neither altered the direction nor its activity. Physiological studies suggested that this Cl- absorptive Isc senses dietary Cl- content; thus when dietary Cl- was low, Cl- absorptive Isc was up-regulated. In contrast, when dietary Cl- was increased, Cl- absorptive Isc was down-regulated. We conclude that an active Cl- extrusion mechanism exists in ENaC-expressing late distal colon and likely operates in parallel with ENaC to facilitate NaCl absorption.

  11. Short-circuit impedance measurement

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Nielsen, Arne Hejde; Poulsen, Niels Kjølstad

    2003-01-01

    Methods for estimating the short-circuit impedance in the power grid are investigated for various voltage levels and situations. The short-circuit impedance is measured, preferably from naturally occurring load changes in the grid, and it is shown that such a measurement system faces different...... kinds of problems at different locations in the grid. This means that the best measurement methodology changes depending on the location in the grid. Three typical examples with different measurement problems at 400 kV, 132 kV and 400 V voltage level are discussed....

  12. Determination of short circuit stresses in an air core reactor using ...

    African Journals Online (AJOL)

    This paper shows the use and effectiveness of finite element method while designing an air core reactor for determining the short circuit forces and stress level due to short circuit. A 500 Amp air core series reactor having nominal voltage rating of 600 Volt was to be designed and to be subjected to a short circuit current of 8 ...

  13. Three-phase short circuit calculation method based on pre-computed surface for doubly fed induction generator

    Science.gov (United States)

    Ma, J.; Liu, Q.

    2018-02-01

    This paper presents an improved short circuit calculation method, based on pre-computed surface to determine the short circuit current of a distribution system with multiple doubly fed induction generators (DFIGs). The short circuit current, injected into power grid by DFIG, is determined by low voltage ride through (LVRT) control and protection under grid fault. However, the existing methods are difficult to calculate the short circuit current of DFIG in engineering practice due to its complexity. A short circuit calculation method, based on pre-computed surface, was proposed by developing the surface of short circuit current changing with the calculating impedance and the open circuit voltage. And the short circuit currents were derived by taking into account the rotor excitation and crowbar activation time. Finally, the pre-computed surfaces of short circuit current at different time were established, and the procedure of DFIG short circuit calculation considering its LVRT was designed. The correctness of proposed method was verified by simulation.

  14. Capacitive short circuit detection in transformer core laminations

    International Nuclear Information System (INIS)

    Schulz, Carl A.; Duchesne, Stephane; Roger, Daniel; Vincent, Jean-Noel

    2008-01-01

    A capacitive measurement procedure is proposed that serves to detect burr-induced short circuits in transformer core laminations. The tests are conducted on stacks of transformer steel sheets as used for transformer core production and yield a short-circuit probability indicative of the additional eddy current losses to be expected. Applied during the assembly of transformer cores, the measurements can help to decide whether the burr treatment process is working efficiently or has to be readjusted

  15. Wireless system for location of permanent faults by short circuit current monitoring in electric power distribution network; Sistema wireless para localizacao de faltas permanentes atraves da monitoracao da corrente de curto-circuito em redes de distribuicao de energia eletrica

    Energy Technology Data Exchange (ETDEWEB)

    Machado, A.G.; Correa, A.C.; Machado, R.N. das M.; Ferreira, A.M.D.; Pinto, J.A.C. [Instituto Federal de Educacao, Ciencia e Tecnologia do Para (IFPA), Belem, PA (Brazil)], E-mail: alcidesmachado000@yahoo.com.br; Barra Junior, W. [Universidade Federal do Para (UFPA), Belem, PA (Brazil). Inst. de Tecnologia. Faculdade de Engenharia Eletrica], E-mail: walbarra@ufpa.br

    2009-07-01

    This paper presents the development of an automatic system for permanent short-circuits location in medium voltage (13.8 kV) electric power system distribution feeders, by indirect monitoring of the line current. When a permanent failure occurs, the developed system uses mobile telephony (GSM) text messages (SMS) to inform the power company operation center where the failure most likely took place. With this information in real time, the power company operation center may provide the network restoration in a faster and efficient way. (author)

  16. Relationships between body mass index and short-circuit current in human duodenal and colonic mucosal biopsies. Osbak PS, Bindslev N, Hansen MB. Acta Physiol (Oxf). 2011 Jan;201(1):47-53

    DEFF Research Database (Denmark)

    Osbak, Philip Samuel; Bindslev, Niels; Berner-Hansen, Mark

    2011-01-01

    Aim: Retrospectively, to investigate the relationship between body mass index (BMI) and basal electrogenic transport as measured by short-circuit current (SCC) in human duodenal and colonic mucosal biopsies. Methods: The study included biopsies from mucosa of normal appearance in the sigmoid colon...... and >25 kg m)2). Statistical significance was assessed by the unpaired t-test or Wilcoxon rank-sum test. Correlation coefficients were calculated by Pearson product moment correlation. Results: In colonic biopsies, basal SCC (mean standard deviation) was significantly higher in 59 biopsies from 30...

  17. Development of a safety case for the use of current limiting devices to manage short circuit currents on electrical distribution networks. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    The original objective of this study was to review the safety issues associated with the use of current limiting devices and to write a risk assessment in accordance with good practice. But, when legislative procedures became apparent, the scope was changed to include involvement with the HSE, the DTI and Ofgem. It turned out that it would have been very difficult to write a safety case that would satisfy all of the agencies, or a risk assessment that would cover all applications. The scope of the study was therefore changed to focus on how the existing barriers should be tackled and the implications of the existing legislation. The approach to the study is described; it included reviews of background information and literature, questionnaires to manufacturers, a review of the reliability and hazards of the devices, and a review of UK safety legislation. The Final Report describes all this and includes discussion on the consequences of failure of fault current limiting devices, control measures which could be used to minimise risk, and recommendations for a way forward.

  18. Simulation and experimental study on lithium ion battery short circuit

    International Nuclear Information System (INIS)

    Zhao, Rui; Liu, Jie; Gu, Junjie

    2016-01-01

    Highlights: • Both external and internal short circuit tests were performed on Li-ion batteries. • An electrochemical–thermal model with an additional nail site heat source is presented. • The model can accurately simulate the temperature variations of non-venting batteries. • The model is reliable in predicting the occurrence and start time of thermal runaway. • A hydrogel cooling system proves its strength in preventing battery thermal runaway. - Abstract: Safety is the first priority in lithium ion (Li-ion) battery applications. A large portion of electrical and thermal hazards caused by Li-ion battery is associated with short circuit. In this paper, both external and internal short circuit tests are conducted. Li-ion batteries and battery packs of different capacities are used. The results indicate that external short circuit is worse for smaller size batteries due to their higher internal resistances, and this type of short can be well managed by assembling fuses. In internal short circuit tests, higher chance of failure is found on larger capacity batteries. A modified electrochemical–thermal model is proposed, which incorporates an additional heat source from nail site and proves to be successful in depicting temperature changes in batteries. Specifically, the model is able to estimate the occurrence and approximate start time of thermal runaway. Furthermore, the effectiveness of a hydrogel based thermal management system in suppressing thermal abuse and preventing thermal runaway propagation is verified through the external and internal short tests on batteries and battery packs.

  19. Proposition algebra and short-circuit logic

    NARCIS (Netherlands)

    Bergstra, J.A.; Ponse, A.

    2012-01-01

    Short-circuit evaluation denotes the semantics of propositional connectives in which the second argument is only evaluated if the first argument does not suffice to determine the value of the expression. In programming, short-circuit evaluation is widely used. We review proposition algebra [2010],

  20. Optimization of the front contact to minimize short-circuit current losses in CdTe thin-film solar cells

    Science.gov (United States)

    Kephart, Jason Michael

    With a growing population and rising standard of living, the world is in need of clean sources of energy at low cost in order to meet both economic and environmental needs. Solar energy is an abundant resource which is fundamentally adequate to meet all human energy needs. Photovoltaics are an attractive way to safely convert this energy to electricity with little to no noise, moving parts, water, or arable land. Currently, thin-film photovoltaic modules based on cadmium telluride are a low-cost solution with multiple GW/year commercial production, but have lower conversion efficiency than the dominant technology, crystalline silicon. Increasing the conversion efficiency of these panels through optimization of the electronic and optical structure of the cell can further lower the cost of these modules. The front contact of the CdTe thin-film solar cell is critical to device efficiency for three important reasons: it must transmit light to the CdTe absorber to be collected, it must form a reasonably passive interface and serve as a growth template for the CdTe, and it must allow electrons to be extracted from the CdTe. The current standard window layer material, cadmium sulfide, has a low bandgap of 2.4 eV which can block over 20% of available light from being converted to mobile charge carriers. Reducing the thickness of this layer or replacing it with a higher-bandgap material can provide a commensurate increase in device efficiency. When the CdS window is made thinner, a degradation in electronic quality of the device is observed with a reduction in open-circuit voltage and fill factor. One commonly used method to enable a thinner optimum CdS thickness is a high-resistance transparent (HRT) layer between the transparent conducting oxide electrode and window layer. The function of this layer has not been fully explained in the literature, and existing hypotheses center on the existence of pinholes in the window layer which are not consistent with observed results

  1. On-line diagnosis of inter-turn short circuit fault for DC brushed motor.

    Science.gov (United States)

    Zhang, Jiayuan; Zhan, Wei; Ehsani, Mehrdad

    2018-04-11

    Extensive research effort has been made in fault diagnosis of motors and related components such as winding and ball bearing. In this paper, a new concept of inter-turn short circuit fault for DC brushed motors is proposed to include the short circuit ratio and short circuit resistance. A first-principle model is derived for motors with inter-turn short circuit fault. A statistical model based on Hidden Markov Model is developed for fault diagnosis purpose. This new method not only allows detection of motor winding short circuit fault, it can also provide estimation of the fault severity, as indicated by estimation of the short circuit ratio and the short circuit resistance. The estimated fault severity can be used for making appropriate decisions in response to the fault condition. The feasibility of the proposed methodology is studied for inter-turn short circuit of DC brushed motors using simulation in MATLAB/Simulink environment. In addition, it is shown that the proposed methodology is reliable with the presence of small random noise in the system parameters and measurement. Copyright © 2018 ISA. Published by Elsevier Ltd. All rights reserved.

  2. A Comprehensive Investigation on the Short Circuit Performance of MW-level IGBT Power Modules

    DEFF Research Database (Denmark)

    Wu, Rui; Reigosa, Paula Diaz; Iannuzzo, Francesco

    2015-01-01

    This paper investigates the short circuit performance of commercial 1.7 kV / 1 kA IGBT power modules by means of a 6 kA Non-Destructive-Tester. A mismatched current distribution among the parallel chips has been observed, which can reduce the short circuit capability of the IGBT power module unde...

  3. LS1 Report: short-circuit tests

    CERN Document Server

    Katarina Anthony

    2014-01-01

    As the LS1 draws to an end, teams move from installation projects to a phase of intense testing. Among these are the so-called 'short-circuit tests'. Currently under way at Point 7, these tests verify the cables, the interlocks, the energy extraction systems, the power converters that provide current to the superconducting magnets and the cooling system.   Thermal camera images taken during tests at point 4 (IP4). Before putting beam into the LHC, all of the machine's hardware components need to be put to the test. Out of these, the most complicated are the superconducting circuits, which have a myriad of different failure modes with interlock and control systems. While these will be tested at cold - during powering tests to be done in August - work can still be done beforehand. "While the circuits in the magnets themselves cannot be tested at warm, what we can do is verify the power converter and the circuits right up to the place the cables go into the magn...

  4. Achieving 12.8% Efficiency by Simultaneously Improving Open-Circuit Voltage and Short-Circuit Current Density in Tandem Organic Solar Cells.

    Science.gov (United States)

    Qin, Yunpeng; Chen, Yu; Cui, Yong; Zhang, Shaoqing; Yao, Huifeng; Huang, Jiang; Li, Wanning; Zheng, Zhong; Hou, Jianhui

    2017-06-01

    Tandem organic solar cells (TOSCs), which integrate multiple organic photovoltaic layers with complementary absorption in series, have been proved to be a strong contender in organic photovoltaic depending on their advantages in harvesting a greater part of the solar spectrum and more efficient photon utilization than traditional single-junction organic solar cells. However, simultaneously improving open circuit voltage (V oc ) and short current density (J sc ) is a still particularly tricky issue for highly efficient TOSCs. In this work, by employing the low-bandgap nonfullerene acceptor, IEICO, into the rear cell to extend absorption, and meanwhile introducing PBDD4T-2F into the front cell for improving V oc , an impressive efficiency of 12.8% has been achieved in well-designed TOSC. This result is also one of the highest efficiencies reported in state-of-the-art organic solar cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Short-Circuit Calculations for a Transmission Line in the Algerian Power Network Compensated by Thyristor Controlled Voltage Regulator

    Directory of Open Access Journals (Sweden)

    ZELLAGUI Mohamed

    2014-10-01

    Full Text Available In this paper, the impact of using the Thyristor Controlled Voltage Regulator (TCVR on short-circuit calculations is studied for a high voltage transmission line in case of a phase to earth fault in the presence of a fault resistance (RF. A 400 kV single transmission line, in the Algerian power network, is used for this study where the line is compensated by TCVR FACTS device to control the voltage and active power of the line. The impact of the fault resistance is studied to reflect its effect on short-circuit calculations including symmetrical current components, transmission line currents, voltage symmetrical components, and transmission line voltages, without and with TCVR. The obtained simulation results match the presented theoretical analysis.

  6. Estimating the short-circuit impedance

    DEFF Research Database (Denmark)

    Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

    1997-01-01

    through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...... a simultaneously measurement of impedance and flicker....

  7. Evaporating short-circuits in the ATLAS liquid argon barrel presampler 006

    CERN Document Server

    Belhorma, B; Lund-Jensen, B; Rydström, S; Yamouni, M

    2005-01-01

    A technique to eliminate or limit the implications of short-circuits in the ATLAS barrel presampler is described. A high voltage capacitor with a large capacity is charged at different high voltages and discharged through the short-circuit which allows either to disintegrate the dust being the origin of the short-circuit, or to burn away a thin etched copper strip which acts as a fuse on the corresponding presampler anode. This effect is possible even in the presence of a resistive HV cable (10 to 30 ohms) in series which dampens the pulse.

  8. Short-circuit testing of monofilar Bi-2212 coils connected in series and in parallel

    International Nuclear Information System (INIS)

    Polasek, A; Dias, R; Serra, E T; Filho, O O; Niedu, D

    2010-01-01

    Superconducting Fault Current Limiters (SCFCL's) are one of the most promising technologies for fault current limitation. In the present work, resistive SCFCL components based on Bi-2212 monofilar coils are subjected to short-circuit testing. These SCFCL components can be easily connected in series and/or in parallel by using joints and clamps. This allows a considerable flexibility to developing larger SCFCL devices, since the configuration and size of the whole device can be easily adapted to the operational conditions. The single components presented critical current (Ic) values of 240-260 A, at 77 K. Short-circuits during 40-120 ms were applied. A single component can withstand a voltage drop of 126-252 V (0.3-0.6 V/cm). Components connected in series withstand higher voltage levels, whereas parallel connection allows higher rated currents during normal operation, but the limited current is also higher. Prospective currents as high as 10-40 kA (peak value) were limited to 3-9 kA (peak value) in the first half cycle.

  9. Superconducting fault current limiter using high-resistive YBCO tapes

    International Nuclear Information System (INIS)

    Yazawa, T.; Koyanagi, K.; Takahashi, M.; Ono, M.; Toba, K.; Takigami, H.; Urata, M.; Iijima, Y.; Saito, T.; Ameniya, N.; Shiohara, Y.

    2008-01-01

    One of the programs in the Ministry of Economy and Trade and Industry (METI) project regarding R and D on YBCO conductor is to evaluate the applicability of the developed conductor toward several applications. This paper focuses on a fault current limiter (FCL) as one of the expected power applications. YBCO tape conductors with ion beam assisted deposition (IBAD) substrate are used in this work. In order to obtain high resistance of the conductor, which is preferable to an FCL, the thickness of the protecting layer made of silver was decreased as possible. Then high-resistive metal stabilizing layer is attached on the silver layer to improve stability. Obtaining the relevant current limiting performance on short sample experiments, model coils were developed to aim the 6.6 kV-class FCL. Short circuit experiments were implemented with a short circuit generator. The coil successfully restricted the short circuit current over 17 kA to about 700 A by the applied voltage of 3.8 kV, which is nominal phase-to-ground voltage. The experimental results show good agreement with computer analyses and show promising toward the application

  10. Automatic location of short circuit faults

    Energy Technology Data Exchange (ETDEWEB)

    Lehtonen, M. [VTT Energy, Espoo (Finland); Hakola, T.; Antila, E. [ABB Power Oy (Finland); Seppaenen, M. [North-Carelian Power Company (Finland)

    1998-08-01

    In this chapter, the automatic location of short circuit faults on medium voltage distribution lines, based on the integration of computer systems of medium voltage distribution network automation is discussed. First the distribution data management systems and their interface with the substation telecontrol, or SCADA systems, is studied. Then the integration of substation telecontrol system and computerized relay protection is discussed. Finally, the implementation of the fault location system is presented and the practical experience with the system is discussed

  11. An iterative approach for symmetrical and asymmetrical Short-circuit calculations with converter-based connected renewable energy sources

    DEFF Research Database (Denmark)

    Göksu, Ömer; Teodorescu, Remus; Bak-Jensen, Birgitte

    2012-01-01

    , an iterative approach for short-circuit calculation of networks with power converter-based wind turbines is developed for both symmetrical and asymmetrical short-circuit grid faults. As a contribution to existing solutions, negative sequence current injection from the wind turbines is also taken into account...... in calculations in case of asymmetrical faults. The developed iterative short-circuit calculation method is verified with time domain simulations....

  12. Synchronous Condenser Allocation for Improving System Short Circuit Ratio

    DEFF Research Database (Denmark)

    Jia, Jundi; Yang, Guangya; Nielsen, Arne Hejde

    2018-01-01

    With converter-based renewable energy sources increasingly integrated into power systems and conventional power plants gradually phased out, future power systems will experience reduced short circuit strength. The deployment of synchronous condensers can serve as a potential solution. This paper...... presents an optimal synchronous condenser allocation method for improving system short circuit ratio at converter point of common coupling using a modified short circuit analysis approach. The total cost of installing new synchronous condensers is minimized while the system short circuit ratios...

  13. 30 CFR 57.12065 - Short circuit and lightning protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit and lightning protection. 57... MINES Electricity Surface Only § 57.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

  14. 30 CFR 56.12065 - Short circuit and lightning protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Short circuit and lightning protection. 56... Electricity § 56.12065 Short circuit and lightning protection. Powerlines, including trolley wires, and telephone circuits shall be protected against short circuits and lightning. ...

  15. Investigation and Classification of Short-Circuit Failure Modes Based on Three-Dimensional Safe Operating Area for High-Power IGBT Modules

    DEFF Research Database (Denmark)

    Chen, Yuxiang; Li, Wuhua; Iannuzzo, Francesco

    2018-01-01

    , in order to establish the current state of the art and trends in this area. First, the concept of 3-D safe operating area is proposed as the IGBT's operational boundary to divide the device short-circuit failure modes into short-circuit VDC/Vrated-ISC SOA limiting and short-circuit endurance time limiting...... groups. Then, the discussion is centered on currently reported IGBT short-circuit failure modes in terms of their relationships with the device 3-D short-circuit safe operating area (3D-SCSOA) characteristics. In addition, further investigation on the interaction of 3D-SCSOA characteristics...

  16. Resistive-Type Fault Current Limiter

    Science.gov (United States)

    Martini, L.; Bocchi, M.; Angeli, G.

    Among the wide range of High-Temperature Superconducting (HTS) materials presently known Bismuth Strontium Calcium Copper Oxide (BSCCO) is a very suitable candidate for power applications either at low temperature (e.g. mechanical and economic point of view. In particular, BSCCO has been proven to be particularly suitable for hybrid current leads and HTS cables. However, BSCCO-based Superconducting Fault Current Limiter (SFCL) applications have been an important issue within the Ricerca sul Sistema Energetico (RSE) S.p.A. R&D portfolio in the last decade. The SFCL project, funded in the framework of a R&D national project, started focusing on a preliminary single-phase device, which was submitted to dielectric and short-circuit current testing. The first success paved the way for the finalization of the remaining two phases and the final result was a three-phase resistive-type 9 kV/3.4 MVA SFCL device, based on first generation (1G) BSCCO tapes that was installed in the S. Dionigi substation, belonging to the Italian utility A2A Reti Elettriche S.p.A. (A2A), in the Milan MV distribution grid. The in-field activity lasted for more than two years, demonstrating the SFCL capability to cope with the grid in every-day operating conditions. Moreover, at the end of the experimentation, the SFCL device was able to perform a true limitation during a three-phase fault, thereby becoming one of the first SFCL devices in the world (the first in Italy) installed in a real grid and to have limited a real short-circuit current.

  17. A Short-Circuit Method for Networks.

    Science.gov (United States)

    Ong, P. P.

    1983-01-01

    Describes a method of network analysis that allows avoidance of Kirchoff's Laws (providing the network is symmetrical) by reduction to simple series/parallel resistances. The method can be extended to symmetrical alternating current, capacitance or inductance if corresponding theorems are used. Symmetric cubic network serves as an example. (JM)

  18. Regulated Short Circuit Protected Power Supply.

    Science.gov (United States)

    The patent describes a voltage regulated power supply . It uses a small series resistance to sense load current and a circuit including a normally...includes a latching zener diode connected to the base of the trigger transistor to maintain its ’on’ condition after overload to maintain the power supply inoperative until the fault is removed and the supply is recycled.

  19. Mineral processing by short circuits in protoplanetary disks

    DEFF Research Database (Denmark)

    Mcnally, C.P.; Hubbard, A.; Mac Low, M.-M.

    2013-01-01

    , as evidenced by observations of spectra characteristic of crystalline silicates. One possible environment for this process is the turbulent magnetohydrodynamic flow thought to drive accretion in these disks. Such flows generally form thin current sheets, which are sites of magnetic reconnection, and dissipate......Meteoritic chondrules were formed in the early solar system by brief heating of silicate dust to melting temperatures. Some highly refractory grains (Type B calcium-aluminum-rich inclusions, CAIs) also show signs of transient heating. A similar process may occur in other protoplanetary disks...... the magnetic fields amplified by a disk dynamo. We suggest that it is possible to heat precursor grains for chondrules and other high-temperature minerals in current sheets that have been concentrated by our recently described short-circuit instability. We extend our work on this process by including...

  20. Short-Circuit Modeling of a Wind Power Plant: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Muljadi, E.; Gevorgian, V.

    2011-03-01

    This paper investigates the short-circuit behavior of a WPP for different types of wind turbines. The short-circuit behavior will be presented. Both the simplified models and detailed models are used in the simulations and both symmetrical faults and unsymmetrical faults are discussed.

  1. Packaging Solutions for Mitigating IGBT Short-Circuit Instabilities

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Blaabjerg, Frede

    2017-01-01

    layout parameters must be minimized. This study is important to reach conclusions on the package design requirements for optimum performance under short-circuit operations, revealing the compromises between switching speed and short-circuit performance. Finally, an optimized layout solution...

  2. A Computer Program for Short Circuit Analysis of Electric Power ...

    African Journals Online (AJOL)

    This paper described the mathematical basis and computational framework of a computer program developed for short circuit studies of electric power systems. The Short Circuit Analysis Program (SCAP) is to be used to assess the composite effects of unbalanced and balanced faults on the overall reliability of electric ...

  3. Short circuit signatures from different wind turbine generator types

    DEFF Research Database (Denmark)

    Martinez, Jorge; Kjær, Philip C.; Rodriguez, Pedro

    2011-01-01

    , with a synchronous generator, has been simulated. This paper addresses the difficulties that distance or overcurrent relays can experience when they are used in wind power plants. Whereas the short circuit contribution from power plants with synchronous generators can be calculated on the basis of the machine...... faults, and the consequent effects on substation protections, the aforementioned configurations have been simulated using PSCAD/EMTDC, with the same power plant configuration, electrical grid and generator data. Additionally, a comparison of these wind turbine technologies with a conventional power plant......Modern wind power plants are required and designed to ride through faults in the network, subjected to the fault clearance and following grid code demands. Beside voltage support during faults, the wind turbine fault current contribution is important to establish the correct settings for the relay...

  4. On-Demand Cell Internal Short Circuit Device

    Science.gov (United States)

    Darcy, Eric; Keyser, Matthew

    2014-01-01

    A device implantable in Li-ion cells that can generate a hard internal short circuit on-demand by exposing the cell to 60?C has been demonstrated to be valuable for expanding our understanding of cell responses. The device provides a negligible impact to cell performance and enables the instigation of the 4 general categories of cell internal shorts to determine relative severity and cell design susceptibility. Tests with a 18650 cell design indicates that the anode active material short to the aluminum cathode current collector tends to be more catastrophic than the 3 other types of internal shorts. Advanced safety features (such as shutdown separators) to prevent or mitigate the severity of cell internal shorts can be verified with this device. The hard short success rate achieved to date in 18650 cells is about 80%, which is sufficient for using these cells in battery assemblies for field-failure-relevant, cell-cell thermal runaway propagation verification tests

  5. In-situ short circuit protection system and method for high-energy electrochemical cells

    Science.gov (United States)

    Gauthier, Michel; Domroese, Michael K.; Hoffman, Joseph A.; Lindeman, David D.; Noel, Joseph-Robert-Gaetan; Radewald, Vern E.; Rouillard, Jean; Rouillard, Roger; Shiota, Toshimi; Trice, Jennifer L.

    2000-01-01

    An in-situ thermal management system for an energy storage device. The energy storage device includes a plurality of energy storage cells each being coupled in parallel to common positive and negative connections. Each of the energy storage cells, in accordance with the cell's technology, dimensions, and thermal/electrical properties, is configured to have a ratio of energy content-to-contact surface area such that thermal energy produced by a short-circuit in a particular cell is conducted to a cell adjacent the particular cell so as to prevent the temperature of the particular cell from exceeding a breakdown temperature. In one embodiment, a fuse is coupled in series with each of a number of energy storage cells. The fuses are activated by a current spike capacitively produced by a cell upon occurrence of a short-circuit in the cell, thereby electrically isolating the short-circuited cell from the common positive and negative connections.

  6. In-situ short-circuit protection system and method for high-energy electrochemical cells

    Science.gov (United States)

    Gauthier, Michel; Domroese, Michael K.; Hoffman, Joseph A.; Lindeman, David D.; Noel, Joseph-Robert-Gaetan; Radewald, Vern E.; Rouillard, Jean; Rouillard, Roger; Shiota, Toshimi; Trice, Jennifer L.

    2003-04-15

    An in-situ thermal management system for an energy storage device. The energy storage device includes a plurality of energy storage cells each being coupled in parallel to common positive and negative connections. Each of the energy storage cells, in accordance with the cell's technology, dimensions, and thermal/electrical properties, is configured to have a ratio of energy content-to-contact surface area such that thermal energy produced by a short-circuit in a particular cell is conducted to a cell adjacent the particular cell so as to prevent the temperature of the particular cell from exceeding a breakdown temperature. In one embodiment, a fuse is coupled in series with each of a number of energy storage cells. The fuses are activated by a current spike capacitively produced by a cell upon occurrence of a short-circuit in the cell, thereby electrically isolating the short-circuited cell from the common positive and negative connections.

  7. Short Circuits of a 10-MW High-Temperature Superconducting Wind Turbine Generator

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Liu, Dong; Polinder, Henk

    2017-01-01

    Direct Drive high-temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits take...... place at generator terminals. In this paper, a finite element model that couples magnetic fields and the generator's equivalent circuits is developed to simulate short-circuit faults. Afterward, the model is used to study the transient performance of a 10-MW HTS wind turbine generator under four...... show that the short circuits pose great challenges to the generator, and careful consideration should be given to protect the generator. The findings presented in this paper would be beneficial to the design, operation and protection of an HTS wind turbine generator....

  8. Short Circuits of a 10 MW High Temperature Superconducting Wind Turbine Generator

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Liu, Dong; Polinder, Henk

    2016-01-01

    Direct drive high temperature superconducting (HTS) wind turbine generators have been proposed to tackle challenges for ever increasing wind turbine ratings. Due to smaller reactances in HTS generators, higher fault currents and larger transient torques could occur if sudden short circuits happen...... at generator terminals. In this paper, a finite element model that couples magnetic fields and the generator’s equivalent circuits is developed to simulate short circuit faults. Afterwards, the model is used to study the transient performance of a 10 MW HTS wind turbine generator under four different short...

  9. Electro-thermal modeling of high power IGBT module short-circuits with experimental validation

    DEFF Research Database (Denmark)

    Wu, Rui; Iannuzzo, Francesco; Wang, Huai

    2015-01-01

    A novel Insulated Gate Bipolar Transistor (IGBT) electro-thermal modeling approach involving PSpice and ANSYS/Icepak with both high accuracy and simulation speed has been presented to study short-circuit of a 1.7 kV/1 kA commercial IGBT module. The approach successfully predicts the current...

  10. Short circuit protection for a power distribution system

    Science.gov (United States)

    Owen, J. R., III

    1969-01-01

    Sensing circuit detects when the output from a matrix is present and when it should be present. The circuit provides short circuit protection for a power distribution system where the selection of the driven load is accomplished by digital logic.

  11. Utilisation of symmetrical components in a communication-based protection for loop MV feeders with variable short-circuit power

    DEFF Research Database (Denmark)

    Ciontea, Catalin-Iosif; Bak, Claus Leth; Blaabjerg, Frede

    2018-01-01

    Variability of the available short-circuit power also implies variation of the fault level, which can potentially cause several protection problems in the electric networks. In this paper, a novel protection method that is insensitive to the fault level changes caused by variable short......-circuit power is presented. It relies on utilisation of symmetrical components of the short-circuit currents and on communication between the protection relays. The proposed method addresses the Single Phase to Ground (SPG) faults occurring in directly grounded distribution networks, with focus on closed......-loop Medium Voltage (MV) feeders. Case studies are presented, which demonstrate that the proposed protection scheme is capable of effectively detecting the SPG faults in closed-loop feeders with variable short-circuit power....

  12. Short-circuit protection of LLC resonant converter using voltages across resonant tank elements

    Directory of Open Access Journals (Sweden)

    Denys Igorovych Zaikin

    2015-06-01

    Full Text Available This paper describes two methods for the short-circuit protection of the LLC resonant converter. One of them uses the voltage across the capacitor and the other uses the voltage across the inductor of the resonant tank. These voltages can be processed (integrated or differentiated to recover the resonant tank current. The two circuits illustrated in the described methods make it possible to develop a robust LLC converter design and to avoid using lossy current measurement elements, such as a shunt resistor or current transformer. The methods also allow measuring resonant tank current without breaking high-current paths and connecting the measuring circuit in parallel with the inductor or capacitor of the resonant tank. Practical implementations of these indirect current measurements have been experimentally tested for the short-circuit protection of the 1600 W LLC converter.

  13. The short circuit instability in protoplanetary disks

    DEFF Research Database (Denmark)

    Hubbard, A.; McNally, C.P.; Mac Low, M.M.

    2013-01-01

    We introduce a magneto-hydrodynamic instability which occurs, among other locations, in the inner, hot regions of protoplanetary disks, and which alters the way in which resistive dissipation of magnetic energy into heat proceeds. This instability can be likened to both an electrical short circui...

  14. Prevention of short circuits in solution-processed OLED devices

    NARCIS (Netherlands)

    Jolt Oostra, A.; Blom, P.W.M.; Michels, J.J.

    2014-01-01

    Pinholes in the emitting layer of an organic light emitting diode (OLED), e.g. induced by particle contamination or processing flaws, lead to direct contact between the hole-injection layer (HIL) and the cathode. The resulting short circuits give rise to catastrophic device failure. We demonstrate

  15. TCAD analysis of short-circuit oscillations in IGBTs

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Rahimo, Munaf

    2017-01-01

    Insulated-Gate Bipolar Transistors (IGBTs) exhibit a gate-voltage oscillation phenomenon during short-circuit, which can result in a gate-oxide breakdown. The oscillations have been investigated through device simulations and experimental investigations of a 3.3-kV IGBT. It has been found...

  16. Unstable behaviour of normally-off GaN E-HEMT under short-circuit

    Science.gov (United States)

    Martínez, P. J.; Maset, E.; Sanchis-Kilders, E.; Esteve, V.; Jordán, J.; Bta Ejea, J.; Ferreres, A.

    2018-04-01

    The short-circuit capability of power switching devices plays an important role in fault detection and the protection of power circuits. In this work, an experimental study on the short-circuit (SC) capability of commercial 600 V Gallium Nitride enhancement-mode high-electron-mobility transistors (E-HEMT) is presented. A different failure mechanism has been identified for commercial p-doped GaN gate (p-GaN) HEMT and metal-insulator-semiconductor (MIS) HEMT. In addition to the well known thermal breakdown, a premature breakdown is shown on both GaN HEMTs, triggered by hot electron trapping at the surface, which demonstrates that current commercial GaN HEMTs has requirements for improving their SC ruggedness.

  17. Control of internal and external short circuits in lithium batteries using a composite thermal switch

    Science.gov (United States)

    Mcdonald, Robert C.; Pickett, Jerome; Goebel, Franz

    1991-01-01

    A composite material has been developed, consisting of a blend of metal and fluorocarbon particles, which behaves as an electronic conductor at room temperature and which abruptly becomes an insulator at a predetermined temperature. This switching behavior results from the difference in thermal expansion coefficients between the conductive and non-conductive portions of the composite. This material was applied as a thin film between the carbon cathode in Li/SOCl2 cells, and the metallic cathode current collector. Using test articles incorporating this feature it was shown that lithium cells externally heated or internally heated during a short circuit lost rate capability and the ability to overheat well below the melting point of lithium (180 C). Thus, during an internal or external cell short circuit, the potential for thermal runaway involving reactions of molten lithium is avoided.

  18. Experimental investigation of internal short circuits in lithium-ion batteries

    Science.gov (United States)

    Poramapojana, Poowanart

    With outstanding performance of Lithium-ion batteries, they have been widely used in many applications. For hybrid electric vehicles and electric vehicles, customer concerns of battery safety have been raised as a number of car accidents were reported. To evaluate safety performance of these batteries, a nail penetration test is used to simulate and induce internal short circuits instantaneously. Efforts to explain failure mechanisms of the penetration using electrochemical-thermal coupled models have been proposed. However, there is no experimental validation because researchers lack of a diagnostic tool to acquire important cell characteristics at a shorting location, such as shorting current and temperature. In this present work, diagnostic nails have been developed to acquire nail center temperatures and shorting current flow through the nails during nail penetration tests. Two types of cylindrical wall structures are used to construct the nails: a double-layered stainless steel wall and a composite cylindrical wall. An inner hollow cylinder functions as a sensor holder where two wires and one thermocouple are installed. To study experimental reproducibility and repeatability of experimental results, two nail penetration tests are conducted using two diagnostic nails with the double-layered wall. Experimental data shows that the shorting resistance at the initial stage is a critical parameter to obtain repeatable results. The average shorting current for both tests is approximately 40 C-rate. The fluctuation of the shorting current is due to random sparks and fire caused loose contacts between the nail and the cell components. Moreover, comparative experimental results between the two wall structures reveal that the wall structure does not affect the cell characteristics and Ohmic heat generation of the nail. The wall structure effects to current measurements inside the nail. With the composite wall, the actual current redistribution into the inner wall is

  19. Short-Circuit Characterization of 10 kV 10A 4H-SiC MOSFET

    DEFF Research Database (Denmark)

    Eni, Emanuel-Petre; Beczkowski, Szymon; Munk-Nielsen, Stig

    2016-01-01

    The short-circuit capability of a power device is highly relevant for converter design and fault protection. In this paper a 10kV 10A 4H-SiC MOSFET is characterized and its short circuit withstand capability is studied and analyzed at 6 kV DC-link voltage. The test setup for this study is also...... introduced as its design, especially the inductance in the switching loop, can affect the experimental results. The study aims to present insights specific to the device which are different from that of silicon (Si) based devices. During the short-circuit operation, MOSFET saturation current, ID......,sat, increases for a few microseconds before decreasing gently. Degradation of the device can be observed at pulses longer than 5.9??s. The SiC MOSFET failed after-turn off, after a pulse of 8.6??s, due to an increase in the leakage current....

  20. Fine-Tuning the Energy Levels of a Nonfullerene Small-Molecule Acceptor to Achieve a High Short-Circuit Current and a Power Conversion Efficiency over 12% in Organic Solar Cells.

    Science.gov (United States)

    Kan, Bin; Zhang, Jiangbin; Liu, Feng; Wan, Xiangjian; Li, Chenxi; Ke, Xin; Wang, Yunchuang; Feng, Huanran; Zhang, Yamin; Long, Guankui; Friend, Richard H; Bakulin, Artem A; Chen, Yongsheng

    2018-01-01

    Organic solar cell optimization requires careful balancing of current-voltage output of the materials system. Here, such optimization using ultrafast spectroscopy as a tool to optimize the material bandgap without altering ultrafast photophysics is reported. A new acceptor-donor-acceptor (A-D-A)-type small-molecule acceptor NCBDT is designed by modification of the D and A units of NFBDT. Compared to NFBDT, NCBDT exhibits upshifted highest occupied molecular orbital (HOMO) energy level mainly due to the additional octyl on the D unit and downshifted lowest unoccupied molecular orbital (LUMO) energy level due to the fluorination of A units. NCBDT has a low optical bandgap of 1.45 eV which extends the absorption range toward near-IR region, down to ≈860 nm. However, the 60 meV lowered LUMO level of NCBDT hardly changes the V oc level, and the elevation of the NCBDT HOMO does not have a substantial influence on the photophysics of the materials. Thus, for both NCBDT- and NFBDT-based systems, an unusually slow (≈400 ps) but ultimately efficient charge generation mediated by interfacial charge-pair states is observed, followed by effective charge extraction. As a result, the PBDB-T:NCBDT devices demonstrate an impressive power conversion efficiency over 12%-among the best for solution-processed organic solar cells. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. NREL/NASA Internal Short-Circuit Instigator in Lithium Ion Cells; NREL (National Renewable Energy Laboratory)

    Energy Technology Data Exchange (ETDEWEB)

    Long, Dirk; Ireland, John; Pesaran, Ahmad; Darcy, Eric; Shoesmith, Mark; McCarthy, Ben

    2013-11-14

    NREL has developed a device to test one of the most challenging failure mechanisms of lithium-ion (Li-ion) batteries -- a battery internal short circuit. Many members of the technical community believe that this type of failure is caused by a latent flaw that results in a short circuit between electrodes during use. As electric car manufacturers turn to Li-ion batteries for energy storage, solving the short circuit problem becomes more important. To date, no reliable and practical method exists to create on-demand internal shorts in Li-ion cells that produce a response that is relevant to the ones produced by field failures. NREL and NASA have worked to establish an improved ISC cell-level test method that simulates an emergent internal short circuit, is capable of triggering the four types of cell internal shorts, and produces consistent and reproducible results. Internal short circuit device design is small, low-profile and implantable into Li-ion cells, preferably during assembly. The key component is an electrolyte-compatible phase change material (PCM). The ISC is triggered by heating the cell above PCM melting temperature (presently 40 degrees C – 60 degrees C). In laboratory testing, the activated device can handle currents in excess of 300 A to simulate hard shorts (< 2 mohms). Phase change from non-conducting to conducting has been 100% successful during trigger tests.

  2. Transient analysis of the output short-circuit fault of high power and high voltage DC power supply

    International Nuclear Information System (INIS)

    Yang Zhigang; Zhang Jian; Huang Yiyun; Hao Xu; Sun Haozhang; Guo Fei

    2014-01-01

    The transient conditions of output short-circuit fault of high voltage DC power supply was introduced, and the energy of power supply injecting into klystron during the protection process of three-electrode gas switch were analyzed and calculated in detail when klystron load happening electrode arc faults. The results of calculation and simulation are consistent with the results of the experiment. When the output short-circuit fault of high voltage power supply occurs, switch can be shut off in the microsecond, and the short circuit current can be controlled in 200 A. It has verified the rapidity and reliability of the three-electrode gas switch protection, and it has engineering application value. (authors)

  3. High Speed Level Converters With Short Circuit Current Reduction

    Directory of Open Access Journals (Sweden)

    Avireni Srinivasulu

    2014-08-01

    Full Text Available The level converter is used as interface between low voltages to high voltage boundary. The efficient level converter has less power consumption and less delay are the design considerations of the level shifter. In this paper two new CMOS level converters are presented with high driving capability with low propagation delay. The proposed level converters are simulated using Cadence software with 0.18 µm CMOS technology. The simulation result shows that the proposed circuits have less propagation delay than the existing ones. The circuits are simulated for different load capacitor values and different voltages. The proposed level converters operate for different input pulse signal amplitude values are +0.8 V, +1 V, +1.2 V and VDDH values of +1.8 V and +3.3 V.

  4. Electromechanical stress in transformers caused by three-phase short-circuits; Estresse eletromecanico em transformadores causado por curtos-circuitos trifasicos

    Energy Technology Data Exchange (ETDEWEB)

    Rosentino, A.J.J. Pereira; Delaiba, A.C.; Saraiva, E.; Oliveira, J.C. de; Lynce, M. [Universidade Federal de Uberlandia (UFU), MG (Brazil). Fac. de Engenharia Eletrica], Emails: arnaldoufu@gmail.com, delaiba@ufu.br, elise.saraiva@yahoo.com.br, jcoliveira@ufu.br, lynce@ufu.br; Bronzeado, H. de S. [Companhia Hidro Eletrica do Sao Francisco (CHESF), Recife, PE (Brazil)], Emails: herivelto.bronzeado@gmail.com, hebron@chesf.gov.br

    2009-07-01

    One of the reasons for internal failures of transformers is the weakness of the isolation of its conductors/coils due to vibrations caused by electromechanics forces produced by the high short-circuit currents. In this context, this paper presents a methodology to estimate the electromechanical stress in transformers caused by three-phase short circuits. Details of the characteristics of radial and axial forces that can occur in concentric windings of transformers, focusing mainly on the axial are presented. It is presented the preliminary description of techniques for diagnosis and monitoring of transformers in the face of mechanical stress caused by short circuit. This study considers the transformers core involved.

  5. Protection Principle for a DC Distribution System with a Resistive Superconductive Fault Current Limiter

    Directory of Open Access Journals (Sweden)

    Shimin Xue

    2015-05-01

    Full Text Available A DC distribution system, which is suitable for access to distributed power generation and DC loads, is one of the development directions in power systems. Furthermore, it could greatly improve the energy efficiency and reduce the loss of power transportation. The huge short circuit current is always a great threat to the safety of the components, especially the capacitors and diodes. A resistive superconductive fault current limiter (SFCL, which could respond quickly once a fault happens and limit the fault current to a relatively low level, becomes a good solution to this problem. In this paper, the operational principle of the resistive SFCL is introduced first, and then, the DC short-circuit fault characteristic of the DC distribution system with the SFCL is analyzed and the effectiveness of the SFCL verified. In order to realize the selectivity of the protection in the DC distribution system with SFCL, a new transient current protection principle based on Ip (the peak value of the current and tp (the transient time that the current takes to reach its peak value is proposed. Finally, a model of a 10-kV DC distribution system with an SFCL is established and simulated in PSCAD/METDC. Simulation results have demonstrated the validity of the analysis and protection principle.

  6. Effects of an electromagnetic shield and armature teeth on the short-circuit performance of a direct drive superconducting generator for 10 MW wind turbines

    DEFF Research Database (Denmark)

    Liu, Dong; Polinder, Henk; Abrahamsen, Asger Bech

    2015-01-01

    reactance. An electromagnetic (EM) shield between the rotor and the stator as well as iron or non-magnetic composite (NMC) armature teeth affects the sub-transient reactance of a superconducting machine so that they play a role in the short-circuit performance of a superconducting wind generator. This paper...... presents a 10 MW superconducting generator design and studies the effects of material, thickness and position of an EM shield and the effects of NMC and iron armature teeth on the torque and the field current density during a three-phase short circuit at the generator terminal. One result shows...... that the short circuit torque is not able to be effectively reduced by varying the EM shield and the armature tooth material. The other result shows that the field current density is likely to exceed its critical value during a short circuit although the EM shield material and the armature tooth material take...

  7. Closed Form Solution of Synchronous Machine Short Circuit Transients

    Directory of Open Access Journals (Sweden)

    Gibson H.M. Sianipar

    2010-05-01

    Full Text Available This paper presents the closed form solution of the synchronous machine transients undergoing short circuit. That analytic formulation has been derived based on linearity and balanced conditions of the fault. Even though restrictive, the proposed method will serve somehow or other as a new resource for EMTP productivity. Indisputably superior, the closed-form formulation has some features inimitable by discretization such as continuity, accuracy and absolute numerical stability. Moreover, it enables us to calculate states at one specific instant independent of previous states or a snapshot, which any discretization methods cannot do.

  8. A Nanostructured Composites Thermal Switch Controls Internal and External Short Circuit in Lithium Ion Batteries

    Science.gov (United States)

    McDonald, Robert C.; VanBlarcom, Shelly L.; Kwasnik, Katherine E.

    2013-01-01

    A document discusses a thin layer of composite material, made from nano scale particles of nickel and Teflon, placed within a battery cell as a layer within the anode and/or the cathode. There it conducts electrons at room temperature, then switches to an insulator at an elevated temperature to prevent thermal runaway caused by internal short circuits. The material layer controls excess currents from metal-to-metal or metal-to-carbon shorts that might result from cell crush or a manufacturing defect

  9. Spectral analysis to detection of short circuit fault of solar photovoltaic modules in strings

    International Nuclear Information System (INIS)

    Sevilla-Camacho, P.Y.; Robles-Ocampo, J.B.; Zuñiga-Reyes, Marco A.

    2017-01-01

    This research work presents a method to detect the number of short circuit faulted solar photovoltaic modules in strings of a photovoltaic system by taking into account speed, safety, and non-use of sensors and specialized and expensive equipment. The method consists on apply the spectral analysis and statistical techniques to the alternating current output voltage of a string and detect the number of failed modules through the changes in the amplitude of the component frequency of 12 kHz. For that, the analyzed string is disconnected of the array; and a small pulsed voltage signal of frequency of 12 kHz introduces him under dark condition and controlled temperature. Previous to the analysis, the signal is analogic filtered in order to reduce the direct current signal component. The spectral analysis technique used is the Fast Fourier Transform. The obtained experimental results were validated through simulation of the alternating current equivalent circuit of a solar cell. In all experimental and simulated test, the method allowed to identify correctly the number of photovoltaic modules with short circuit in the analyzed string. (author)

  10. Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery in a coastal subsurface

    Science.gov (United States)

    Gerardus Zuurbier, Koen; Stuyfzand, Pieter Jan

    2017-02-01

    Coastal aquifers and the deeper subsurface are increasingly exploited. The accompanying perforation of the subsurface for those purposes has increased the risk of short-circuiting of originally separated aquifers. This study shows how this short-circuiting negatively impacts the freshwater recovery efficiency (RE) during aquifer storage and recovery (ASR) in coastal aquifers. ASR was applied in a shallow saltwater aquifer overlying a deeper, confined saltwater aquifer, which was targeted for seasonal aquifer thermal energy storage (ATES). Although both aquifers were considered properly separated (i.e., a continuous clay layer prevented rapid groundwater flow between both aquifers), intrusion of deeper saltwater into the shallower aquifer quickly terminated the freshwater recovery. The presumable pathway was a nearby ATES borehole. This finding was supported by field measurements, hydrochemical analyses, and variable-density solute transport modeling (SEAWAT version 4; Langevin et al., 2007). The potentially rapid short-circuiting during storage and recovery can reduce the RE of ASR to null. When limited mixing with ambient groundwater is allowed, a linear RE decrease by short-circuiting with increasing distance from the ASR well within the radius of the injected ASR bubble was observed. Interception of deep short-circuiting water can mitigate the observed RE decrease, although complete compensation of the RE decrease will generally be unattainable. Brackish water upconing from the underlying aquitard towards the shallow recovery wells of the ASR system with multiple partially penetrating wells (MPPW-ASR) was observed. This leakage may lead to a lower recovery efficiency than based on current ASR performance estimations.

  11. Why are there no short circuits in the arterial network?

    Science.gov (United States)

    Chang, Shyr-Shea; Tu, Shenyinying; Liu, Yu-Hsiu; Savage, Van; Hwang, Sheng-Ping; Roper, Marcus

    2015-11-01

    Efficient transport within vascular networks requires red blood cells be delivered at the same rate to each capillary, to ensure even oxygen supply throughout an organism. However, real vascular systems are massive networks in which distance from the heart to capillary vessels can vary over several orders of magnitude. Why are there no short-circuits? Why don't capillaries closer to the heart receive more red blood cells than farther capillaries? We used the trunk arterial network of a zebrafish embryo as a model for understanding the mechanisms underlying red blood cell partitioning within the microvasculature. Using mathematical modeling and experiments in living zebrafish we show that a tuned hydrodynamic feedback mechanism evenly splits red blood cells between trunk vessels. This key design feature comes at a cost to the overall efficiency of the network in that creating a uniform flux means that many red blood cells no longer travel through capillaries.

  12. Resistive Fault Current Limiter Prototypes: Mechanical and Electrical Analyses

    International Nuclear Information System (INIS)

    Martini, L; Arcos, I; Bocchi, M; Brambilla, R; Dalessandro, R; Frigerio, A; Rossi, V

    2006-01-01

    The problem of excessive short-circuit currents has become an important issue for power systems operators and there are clear indications for a growing interest in superconducting fault current limiter devices for MV and HV grids. In this work, we report on both simulation and electrical testing on single-phase SFCL prototypes developed in the framework of an Italian RTD project to be completed with a 3-phase SFCL unit by the end of 2005

  13. Short-circuit ruggedness assessment of a 1.2 kV/180 A SiC MOSFET power module

    DEFF Research Database (Denmark)

    Ionita, Claudiu; Nawaz, Muhammad; Ilves, Kalle

    2017-01-01

    While investigations on short-circuit ruggedness of discrete SiC MOSFET are widely encountered in the scientific literature, there is not so much research dealing with the operational robustness of high power SiC MOSFET modules. In this paper, the short-circuit (SC) ruggedness under hard switching...... fault (HSF) of a commercial 1.2 kV/180 A SiC MOSFET power module in half-bridge configuration will be presented. The test conditions, such as DC-link voltage (VDC), gate resistance (Rg) and gate-source supply voltage (VGS) are varied systematically to investigate the effect of these parameters...

  14. Analysis of the Processes of Short-Currents Limiting by Transformer with High-Temperature Superconducting Windings

    Directory of Open Access Journals (Sweden)

    Manusov V.Z.

    2017-04-01

    Full Text Available An important advantage of transformers with high-temperature superconducting winding is their ability to limit the short-circuit currents. The article discusses a physico-mathematical model that analyses transient processes at short-circuit currents in electrical networks containing transformers with a high-temperature superconducting winding. One of the main ideas and objectives of this work is to investigate the process of short-circuit currents limiting by means of a transformer with a high-temperature superconductor winding, which makes it possible to combine two series-connected elements in one device: transformer and a reactor. The effectiveness of this method is due to the fact that when the short-circuit currents exceed the critical value of the temperature of the superconductor winding, it goes to the normal state with high winding resistance for short-circuit currents. It is important to know when a superconductor should go over to a normal state with the loss of superconductivity. For this purpose, a program was developed to determine the amount of heat generated by a short-circuit current flowing before it is disconnected. For a transformer with high-temperature superconducting winding with a capacity of 40 MVA, a short circuit must be eliminated after 0.1 seconds, without switching off the transformer. To limit the short-circuit current; it is intended to use a hybrid winding. The performed assessment showed that the return of the winding to the superconducting state, first, depends on the ratio of the short-circuit currents to the operating current. This is the criterion for the return/non-return to the superconducting state.

  15. a computer program for short circuit analysis of electric power systems

    African Journals Online (AJOL)

    ES Obe

    1981-03-01

    Mar 1, 1981 ... framework of a computer program developed for short circuit studies of electric power systems. The Short Circuit Analysis Program (SCAP) is to be used to assess the composite effects of unbalanced and balanced faults on the overall reliability of electric power system. The program uses the symmetrical ...

  16. 30 CFR 75.518 - Electric equipment and circuits; overload and short circuit protection.

    Science.gov (United States)

    2010-07-01

    ... Equipment-General § 75.518 Electric equipment and circuits; overload and short circuit protection. Automatic... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electric equipment and circuits; overload and short circuit protection. 75.518 Section 75.518 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION...

  17. The principle of elaboration of the relay protection against short circuits between the closely placed phases of high voltage electrical line

    Directory of Open Access Journals (Sweden)

    Kiorsak M.

    2015-12-01

    Full Text Available The article is devoted to the elaboration of the principle of relay protection against short circuits between the closely placed phases of higher voltage electrical line with self-compensation, based on the six phase’s symmetrical components. It is shown that the unsymmetrical short circuits between the closely placed phases are characterized by appearance of zero and tertiary sequences of symmetrical components. This fact can be used to choose them for relay protection. The electrical basic circuits and formulas for calculation of the passive parameters of zero and tertiary filters of currents (voltages are done. It is presented the structural-functional basic circuit scheme for relay protection against short circuits between the closely placed phases of higher voltage electrical line with self-compensation.

  18. A Review on Grid-connected Converter Control for Short Circuit Power Provision under Grid Unbalanced Faults

    DEFF Research Database (Denmark)

    Jia, Jundi; Yang, Guangya; Nielsen, Arne Hejde

    2017-01-01

    behave significantly different from the traditional alternators under grid faults. In order to evaluate the potential impact of future converter-based power systems on protective relays, it is necessary to consider diverse current control strategies of voltage source converters (VSC) under unbalanced...... faults as the performance of converters primarily depends on their control objectives. In this paper, current control strategies of VSC under unbalanced faults for short circuit power provision are reviewed in two groups, namely power-characteristic-oriented and voltage-support-oriented control strategy...... respectively. As the fault current provided by converters should be restricted within secure operation limits considering semiconductor capabilities, converter current limit issue is also discussed....

  19. Search of short circuits in the Superconducting coils of the ATLAS detector

    CERN Document Server

    Acerbi, E; Cartegni, G C; Sorbi, M; Volpini, Giovanni

    2005-01-01

    The detection of a short circuit inside the superconducting coils of the ATLAS detector after their installation in the casing is mandatory for the mechanical and electrical safety during a fast discharge of the magnet. The detection of a short circuit by means of a capacitor discharge becomes very difficult once the coils are integrated inside the casing, which behaves as a short-circuited turn strongly coupled with the coils. Under these circumstances a preliminary and careful analysis of the electrical parameters of the electrically coupled system and of the discharge behavior is required in order to clearly detect a short circuit. The paper presents and discusses the results of the analysis and the measurements carried out on the 16 double pancakes of the ATLAS Barrel Toroid after their integration inside the casing.

  20. Development of power supply devices for limitations of short circuit on the ship's hull

    Science.gov (United States)

    Fediuk, R. S.; Cherneev, A. M.

    2016-04-01

    The authors of the paper have analysed the reasons and consequences of single-phase ground faults (hull faults). For all varieties of devices limiting the current single-phase ground faults, the most effective devices were found to be the arc-suppression coils with different switching circuits. In this case the measurement of circuit capacitance takes on a great importance. A number of variants of capacitance measurement is presented in the paper. The authors have had a detailed look at a device, limiting the single-phase short-circuit current. This device was developed on the basis of the Far Eastern Federal University under the direction of Dr. G.E. Kuvshinov. The device is provided with power supply that converts alternating current (AC) to direct current (DC), and is realised due to the use of semiconductor devices - transistors and diodes - in a bridge circuit. The technical outcome of this power supply application consists in the reduction of size and weight parameters (compared to the closest analogues) in order to connect the controlled voltage rectifier to the alternating voltage source, including mass and size of the capacitor bank of the current limiting circuit, and enhancing the dynamic parameters of the stage of uncontrolled charge of the output capacitor of the controlled voltage rectifier.

  1. Minimum short-circuit ratios for grid interconnection of wind farms with induction generators

    Energy Technology Data Exchange (ETDEWEB)

    Reginatto, Romeu; Rocha, Carlos [Western Parana State University (UNIOESTE), Foz do Iguacu, PR (Brazil). Center for Engineering and Exact Sciences], Emails: romeu@unioeste.br, croberto@unioeste.br

    2009-07-01

    This paper concerns the problem of determining the minimum value for the short-circuit ratio which is adequate for the interconnection of a given wind farms to a given grid point. First, a set of 3 criteria is defined in order to characterize the quality/safety of the interconnection: acceptable terminal voltage variations, a minimum active power margin, and an acceptable range for the internal voltage angle. Then, the minimum short circuit ratio requirement is determined for 6 different induction generator based wind turbines, both fixed-speed (with and without reactive power compensation) and variable-speed (with the following control policies: reactive power, power factor, and terminal voltage regulation). The minimum short-circuit ratio is determined and shown in graphical results for the 6 wind turbines considered, for X/R in the range 0-15, also analyzing the effect of more/less stringent tolerances for the interconnection criteria. It is observed that the tighter the tolerances the larger the minimum short-circuit ratio required. For the same tolerances in the interconnection criteria, a comparison of the minimum short circuit ratio required for the interconnection of both squirrel-cage and doubly-fed induction generators is presented, showing that the last requires much smaller values for the short-circuit ratio. (author)

  2. Compact electro-thermal modeling of a SiC MOSFET power module under short-circuit conditions

    DEFF Research Database (Denmark)

    Ceccarelli, Lorenzo; Reigosa, Paula Diaz; Bahman, Amir Sajjad

    2017-01-01

    A novel physics-based, electro-thermal model which is capable of estimating accurately the short-circuit behavior and thermal instabilities of silicon carbide MOSFET multi-chip power modules is proposed in this paper. The model has been implemented in PSpice and describes the internal structure...... of the module, including stray elements in the multi-chip layout, self-heating effect, drain leakage current and threshold voltage mismatch. A lumped-parameter thermal network is extracted in order to estimate the internal temperature of the chips. The case study is a half-bridge power module from CREE with 1...

  3. Detection of Internal Short Circuit in Lithium Ion Battery Using Model-Based Switching Model Method

    Directory of Open Access Journals (Sweden)

    Minhwan Seo

    2017-01-01

    Full Text Available Early detection of an internal short circuit (ISCr in a Li-ion battery can prevent it from undergoing thermal runaway, and thereby ensure battery safety. In this paper, a model-based switching model method (SMM is proposed to detect the ISCr in the Li-ion battery. The SMM updates the model of the Li-ion battery with ISCr to improve the accuracy of ISCr resistance R I S C f estimates. The open circuit voltage (OCV and the state of charge (SOC are estimated by applying the equivalent circuit model, and by using the recursive least squares algorithm and the relation between OCV and SOC. As a fault index, the R I S C f is estimated from the estimated OCVs and SOCs to detect the ISCr, and used to update the model; this process yields accurate estimates of OCV and R I S C f . Then the next R I S C f is estimated and used to update the model iteratively. Simulation data from a MATLAB/Simulink model and experimental data verify that this algorithm shows high accuracy of R I S C f estimates to detect the ISCr, thereby helping the battery management system to fulfill early detection of the ISCr.

  4. The Simulation Computer Based Learning (SCBL) for Short Circuit Multi Machine Power System Analysis

    Science.gov (United States)

    Rahmaniar; Putri, Maharani

    2018-03-01

    Strengthening Competitiveness of human resources become the reply of college as a conductor of high fomal education. Electrical Engineering Program UNPAB (Prodi TE UNPAB) as one of the department of electrical engineering that manages the field of electrical engineering expertise has a very important part in preparing human resources (HR), Which is required by where graduates are produced by DE UNPAB, Is expected to be able to compete globally, especially related to the implementation of Asean Economic Community (AEC) which requires the active participation of graduates with competence and quality of human resource competitiveness. Preparation of HR formation Competitive is done with the various strategies contained in the Seven (7) Higher Education Standard, one part of which is the implementation of teaching and learning process in Electrical system analysis with short circuit analysis (SCA) This course is a course The core of which is the basis for the competencies of other subjects in the advanced semester at Development of Computer Based Learning model (CBL) is done in the learning of interference analysis of multi-machine short circuit which includes: (a) Short-circuit One phase, (B) Two-phase Short Circuit Disruption, (c) Ground Short Circuit Disruption, (d) Short Circuit Disruption One Ground Floor Development of CBL learning model for Electrical System Analysis course provides space for students to be more active In learning in solving complex (complicated) problems, so it is thrilling Ilkan flexibility of student learning how to actively solve the problem of short-circuit analysis and to form the active participation of students in learning (Student Center Learning, in the course of electrical power system analysis.

  5. Detailed Pseudo-Static Drive Train Modelling with Generator Short Circuit

    Science.gov (United States)

    Warnock, Christopher; Infield, David

    2016-09-01

    Drivetrain failures contribute significantly to wind turbine downtime. Although the root causes of these failures are not yet fully understood, transient events are regarded as an important contributory factor. Despite extensive drive train modelling, limited work has been carried out to assess the impact of a generator short circuit on the drivetrain. In most cases, a generator short circuit is classed as a failure in itself with minimal focus on the subsequent effects on the gearbox and other drivetrain components. This paper will look to analyse the loading on the drivetrain for a doubly fed induction generator (DFIG) short circuit event with turbine ride through using a combination of Simulink, Garrad Hassan's Bladed and RomaxWind drive train modelling software.

  6. Allocation of synchronous condensers for restoration of system short-circuit power

    DEFF Research Database (Denmark)

    Marrazi, Emanuel; Yang, Guangya; Weinreich-Jensen, Peter

    2017-01-01

    Modern power systems, employing an increasing number of converter-based renewable energy sources (RES) and decreasing the usage of conventional power plants, are leading to lower levels of short-circuit power and rotational inertia. A solution to this is the employment of synchronous condensers...... in the grid, in order to provide sufficient short-circuit power. This results in the increase of the short-circuit ratio (SCR) at transmission system bus-bars serving as points of interconnection (POI) to renewable generation. Evaluation of the required capacity and grid-location of the synchronous condensers......, isinherently a mixed integer non-linear optimization problem, which could not be done on manual basis considering each type of machine and all bus-bars. This study therefore proposes a method of optimal allocation of synchronous condensers in a hypothetic future scenario of a transmission system fed...

  7. Clearance of short circuited ion optics electrodes by capacitive discharge. [in ion thrusters

    Science.gov (United States)

    Poeschel, R. L.

    1976-01-01

    The ion optics electrodes of low specific impulse (3000 sec) mercury electron bombardment ion thrusters are vulnerable to short circuits by virtue of their relatively small interelectrode spacing (0.5 mm). Metallic flakes from backsputtered deposits are the most probable cause of such 'shorts' and 'typical' flakes have been simulated here using refractory wire that has a representative, but controllable, cross section. Shorting wires can be removed by capacitive discharge without significant damage to the electrodes. This paper describes an evaluation of 'short' removal versus electrode damage for several combinations of capacitor voltage, stored energy, and short circuit conditions.

  8. Prediction of Short-Circuit-Related Thermal Stress in Aged IGBT Modules

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Iannuzzo, Francesco; Uhrenfeldt, Christian

    2016-01-01

    In this paper, the thermal stress on bond wires of aged IGBT modules under short-circuit conditions has been studied with respect to different solder delamination levels. To ensure repeatable test conditions, ad-hoc DBC (direct bond copper) samples with delaminated solder layers have been purposely...... fabricated. The temperature distribution produced by such abnormal conditions has been modelled first by means of FEM simulations and then experimentally validated by means of a non-destructive testing technique including an ultra-fast infrared camera. Results demonstrate a significant imbalance...... in the surface temperature distribution which confirms the hypothesis that short-circuit events produce significantly uneven stresses on bond wires....

  9. Modeling of Short-Circuit-Related Thermal Stress in Aged IGBT Modules

    DEFF Research Database (Denmark)

    Bahman, Amir Sajjad; Iannuzzo, Francesco; Uhrenfeldt, Christian

    2017-01-01

    In this paper, the thermal stress on bond wires of aged IGBT modules under short-circuit conditions has been studied with respect to different solder delamination levels. To ensure repeatable test conditions, ad-hoc DBC (direct bond copper) samples with delaminated solder layers have been purposely...... fabricated. The temperature distribution produced by such abnormal conditions has been modelled first by means of FEM simulations and then experimentally validated by means of a non-destructive testing technique including an ultra-fast infrared camera. Results demonstrate a significant imbalance...... in the surface temperature distribution, which confirms the hypothesis that short-circuit events produce significantly uneven stresses on bond wires....

  10. Allocation of synchronous condensers for restoration of system short-circuit power

    DEFF Research Database (Denmark)

    Marrazi, Emanuel; Yang, Guangya; Weinreich-Jensen, Peter

    2017-01-01

    in the grid, in order to provide sufficient short-circuit power. This results in the increase of the short-circuit ratio (SCR) at transmission system bus-bars serving as points of interconnection (POI) to renewable generation. Evaluation of the required capacity and grid-location of the synchronous condensers......, isinherently a mixed integer non-linear optimization problem, which could not be done on manual basis considering each type of machine and all bus-bars. This study therefore proposes a method of optimal allocation of synchronous condensers in a hypothetic future scenario of a transmission system fed...

  11. Determination of short circuit stresses in an air core reactor using ...

    African Journals Online (AJOL)

    DR OKE

    Corresponding Author: e-mail: ghchitaliya@gmail.com, Tel +91-265-2637209. Abstract. This paper shows the use and effectiveness of finite element method while designing an air core reactor for determining the short circuit forces and stress ...

  12. Non-Destructive Investigation on Short Circuit Capability of Wind-Turbine-Scale IGBT Power Modules

    DEFF Research Database (Denmark)

    Wu, Rui; Iannuzzo, Francesco; Wang, Huai

    2014-01-01

    This paper presents a comprehensive investigation on the short circuit capability of wind-turbine-scale IGBT power modules by means of a 6 kA/1.1 kV non-destructive testing system. A Field Programmable Gate Array (FPGA) supervising unit is adpoted to achieve an accurate time control for short cir...

  13. Network model and short circuit program for the Kennedy Space Center electric power distribution system

    Science.gov (United States)

    1976-01-01

    Assumptions made and techniques used in modeling the power network to the 480 volt level are discussed. Basic computational techniques used in the short circuit program are described along with a flow diagram of the program and operational procedures. Procedures for incorporating network changes are included in this user's manual.

  14. 30 CFR 77.506 - Electric equipment and circuits; overload and short-circuit protection.

    Science.gov (United States)

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electric equipment and circuits; overload and short-circuit protection. 77.506 Section 77.506 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... WORK AREAS OF UNDERGROUND COAL MINES Electrical Equipment-General § 77.506 Electric equipment and...

  15. Short-Circuit Robustness Assessment in Power Electronic Modules for Megawatt Applications

    DEFF Research Database (Denmark)

    Iannuzzo, Francesco

    2016-01-01

    In this paper, threats and opportunities in testing of megawatt power electronic modules under short circuit are presented and discussed, together with the introduction of some basic principles of non-destructive testing, a key technique to allow post-failure analysis. The non-destructive testing...... silicon carbide – and new concepts for nondestructive testing of ultrafast power modules adopting such a technology....

  16. Analysis Impact of Distributed Generation Injection to Profile of Voltage and Short-Circuit Fault in 20 kV Distribution Network System

    Science.gov (United States)

    Mulyadi, Y.; Sucita, T.; Rahmawan, M. D.

    2018-01-01

    This study was a case study in PT. PLN (Ltd.) APJ Bandung area with the subject taken was the installation of distributed generation (DG) on 20-kV distribution channels. The purpose of this study is to find out the effect of DG to the changes in voltage profile and three-phase short circuit fault in the 20-kV distribution system with load conditions considered to be balanced. The reason for this research is to know how far DG can improve the voltage profile of the channel and to what degree DG can increase the three-phase short circuit fault on each bus. The method used in this study was comparing the simulation results of power flow and short-circuit fault using ETAP Power System software with manual calculations. The result obtained from the power current simulation before the installation of DG voltage was the drop at the end of the channel at 2.515%. Meanwhile, the three-phase short-circuit current fault before the DG installation at the beginning of the channel was 13.43 kA. After the installation of DG with injection of 50%, DG power obtained voltage drop at the end of the channel was 1.715% and the current fault at the beginning network was 14.05 kA. In addition, with injection of 90%, DG power obtained voltage drop at the end of the channel was 1.06% and the current fault at the beginning network was 14.13%.

  17. Representation of Type 4 wind turbine generator for steady state short-circuit calculations

    Science.gov (United States)

    Kamara, Wouleye

    Various technical impacts are associated to the interconnection of wind turbine generators to the grid. Among them, the increase of short-circuit levels along with its effect on the settings of protecting relays has long acted as an important inhibiting factor for the interconnection of new wind power plants to the grid. This is especially true at the medium voltage level where networks operate close to their short-circuit design value [1]. As renewable energies are progressively replacing traditional power generation sources, short-circuit studies need to adequately assess the impact of newly interconnected wind power plants on the fault level of the network. For planning and design purposes, short-circuit studies are usually performed using steady-state short-circuit programs. Unfortunately, very few have developed models of wind turbine generators that accurately estimate their fault contribution in the phase domain. In particular, no commercial fault-flow analysis program specifically addresses the modeling of inverter-based wind turbine generators which behavior is based on the inverter's characteristics rather than the generator's. The main contribution of this research work is the development of a simplified and yet accurate model of full-scale converter based wind turbine generator, also called Type 4 wind turbine generator, for steady-state short-circuit calculations. The model reproduces the real behavior of the Type 4 wind turbine generator under fault conditions by correctly accounting for the effect of the full-scale converter. The data used for the model is easily accessible to planning engineers. An additional contribution of this research work is the development of a short-circuit algorithm adapted to support the proposed model of Type 4 wind-turbine generator. Short-circuit algorithm based on modified-augmented-nodal analysis (MANA) is solved iteratively to accommodate the proposed model. The algorithm is successfully implemented in CYME 7.0, a

  18. Consequences and mitigation of saltwater intrusion induced by short-circuiting during aquifer storage and recovery in a coastal subsurface

    NARCIS (Netherlands)

    Zuurbier, Koen; Stuijfzand, Pieter

    2017-01-01

    Coastal aquifers and the deeper subsurface are increasingly exploited. The accompanying perforation of the subsurface for those purposes has increased the risk of short-circuiting of originally separated aquifers. This study shows how this short-circuiting negatively impacts the freshwater

  19. Current enhancement in crystalline silicon photovoltaic by low-cost nickel silicide back contact

    KAUST Repository

    Bahabry, R. R.

    2016-11-30

    We report short circuit current (Jsc) enhancement in crystalline silicon (C-Si) photovoltaic (PV) using low-cost Ohmic contact engineering by integration of Nickel mono-silicide (NiSi) for back contact metallization as an alternative to the status quo of using expensive screen printed silver (Ag). We show 2.6 mA/cm2 enhancement in the short circuit current (Jsc) and 1.2 % increment in the efficiency by improving the current collection due to the low specific contact resistance of the NiSi on the heavily Boron (B) doped Silicon (Si) interface.

  20. Comparison of short-circuit characteristics of trench gate and planar gate U-shaped channel SOI-LIGBTs

    Science.gov (United States)

    Zhang, Long; Zhu, Jing; Sun, Weifeng; Zhao, Minna; Huang, Xuequan; Chen, Jiajun; Shi, Longxing; Chen, Jian; Ding, Desheng

    2017-09-01

    Comparison of short-circuit (SC) characteristics of 500 V rated trench gate U-shaped channel (TGU) SOI-LIGBT and planar gate U-shaped channel (PGU) SOI-LIGBT is made for the first time in this paper. The on-state carrier profile of the TGU structure is reshaped by the dual trenches (a gate trench G1 and a hole barrier trench G2), which leads to a different conduction behavior from that of the PGU structure. The TGU structure exhibits a higher latchup immunity but a severer self-heating effect. At current density (JC) trade-off at JC > 640 A/cm2. Comparison of layouts and fabrication processes are also made between the two types of devices.

  1. NREL/NASA Internal Short-Circuit Instigator in Lithium Ion Cells

    Energy Technology Data Exchange (ETDEWEB)

    Keyser, Matthew; Long, Dirk; Pesaran, Ahmad; Darcy, Eric; Shoesmith, Mark; McCarthy, Ben

    2015-10-11

    Lithium-ion cells provide the highest specific energy (>280 Wh/kg) and energy density (>600 Wh/L) rechargeable battery building block to date with the longest life. Electrode/electrolyte thermal instability and flammability of the electrolyte of Li-ion cells make them prone to catastrophic thermal runaway under some rare internal short circuit conditions. Despite extensive QC/QA, standardized industry safety testing, and over 18 years of manufacturing experience, major recalls have taken place and incidents still occur. Many safety incidents that take place in the field originate due to an internal short that was not detectable or predictable at the point of manufacture. The Internal Short-Circuit Instigator can be used to study types of separators, non-flammable electrolytes, electrolyte additives, fusible tabs, propagation studies, and gas generation within a cell.

  2. Transient stability of DFIG wind turbines at an external short-circuit fault

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    The fast development of wind power generation brings new requirements for wind turbine integration into the network. After clearance of an external short-circuit fault, gridconnected wind turbines should restore their normal operation without power loss caused by disconnections. This article...... concentrates on the transient stability of variable speed wind turbines with doubly fed induction generators (DFIGs) at an external short-circuit fault. A simulation model of a MW-level variable speed wind turbine with a DFIG developed in PSCAD/EMTDC is presented and the control and protection schemes...... are described in detail. The transient process of grid-connected wind turbines with DFIGs at an external shortcircuit fault is analysed, and in critical post-fault situations a measure is proposed for the voltage recovery of DFIG wind turbines after fault clearance. Simulation results demonstrate...

  3. Voltage Recovery of Grid-Connected Wind Turbines with DFIG After a Short-Circuit Fault

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2004-01-01

    The fast development of wind power generation brings new requirements for wind turbine integration to the network. After clearance of an external short-circuit fault, the voltage at the wind turbine terminal should be re-established with minimized power losses. This paper concentrates on voltage...... recovery of variable speed wind turbines with doubly fed induction generators (DFIG). A simulation model of a MW-level variable speed wind turbine with a DFIG developed in PSCAD/EMTDC is presented, and the control and protection schemes are described. A new control strategy is proposed to re......-establish the wind turbine terminal voltage after the clearance of an external short-circuit fault, and the restore the normal operation of the variable speed wind turbine with DFIG, which has been demonstrated by simulation results....

  4. On Demand Internal Short Circuit Device Enables Verification of Safer, Higher Performing Battery Designs

    Energy Technology Data Exchange (ETDEWEB)

    Darcy, Eric; Keyser, Matthew

    2017-05-15

    The Internal Short Circuit (ISC) device enables critical battery safety verification. With the aluminum interstitial heat sink between the cells, normal trigger cells cannot be driven into thermal runaway without excessive temperature bias of adjacent cells. With an implantable, on-demand ISC device, thermal runaway tests show that the conductive heat sinks protected adjacent cells from propagation. High heat dissipation and structural support of Al heat sinks show high promise for safer, higher performing batteries.

  5. A field method for measuring short-circuiting in clay soils

    Science.gov (United States)

    Bouma, J.; Dekker, L. W.; Muilwijk, C. J.

    1981-07-01

    A field method is described for measurement of short-circuiting, which is defined as vertical flow of free water along the walls of continuous macropores in unsaturated soil. A cylinder with a diameter and height of 20 cm is filled with undisturbed surface soil and is placed on a perforated disk in a funnel. The funnel is supported to allow periodic measurement of the volume of outflow from the soil. The assembly is placed along the track of a spray-gun, which is commonly used for sprinkling irrigation. At least four samples can be measured during one run. The method is illustrated by discussing the measured short-circuiting in surface soils of: (1) a heavy clay soil; (2) a light clay soil with two different types of structure in and adjacent to potato ridges; and (3) a heavy clay soil with two types of surface microrelief. Short-circuiting is unfavourable because water moves rapidly beyond the root zone without moistening and leaching the soil between the macropores. The water may carry surface-applied fertilizers.

  6. A survey of SiC power MOSFETs short-circuit robustness and failure mode analysis

    DEFF Research Database (Denmark)

    Ceccarelli, L.; Reigosa, P. D.; Iannuzzo, F.

    2017-01-01

    The aim of this paper is to provide an extensive overview about the state-of-art commercially available SiC power MOSFET, focusing on their short-circuit ruggedness. A detailed literature investigation has been carried out, in order to collect and understand the latest research contribution withi...... this topic and create a survey of the present scenario of SiC MOSFETs reliability evaluation and failure mode analysis, pointing out the evolution and improvements as well as the future challenges in this promising device technology....

  7. Simplified Calculation of Maximum Wire Tension in case of Short Circuit

    Directory of Open Access Journals (Sweden)

    I. I. Sergey

    2007-01-01

    Full Text Available Modified method for a simplified calculation of a maximum wire tension in case of a short circuit. This method makes it possible to take into account a real trajectory of their movement and elements of a switch-gear. An accuracy evaluation of the simplified calculation has been done with the help of a calculative experiment using a BusEf computer software. A correction factor has been obtained to take into account an influence of insulator strings on a tension value.

  8. Voltage Recovery of Grid-Connected Wind Turbines with DFIG After a Short-Circuit Fault

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2004-01-01

    recovery of variable speed wind turbines with doubly fed induction generators (DFIG). A simulation model of a MW-level variable speed wind turbine with a DFIG developed in PSCAD/EMTDC is presented, and the control and protection schemes are described. A new control strategy is proposed to re......-establish the wind turbine terminal voltage after the clearance of an external short-circuit fault, and the restore the normal operation of the variable speed wind turbine with DFIG, which has been demonstrated by simulation results....

  9. Transient stability of DFIG wind turbines at an external short-circuit fault

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2005-01-01

    concentrates on the transient stability of variable speed wind turbines with doubly fed induction generators (DFIGs) at an external short-circuit fault. A simulation model of a MW-level variable speed wind turbine with a DFIG developed in PSCAD/EMTDC is presented and the control and protection schemes...... are described in detail. The transient process of grid-connected wind turbines with DFIGs at an external shortcircuit fault is analysed, and in critical post-fault situations a measure is proposed for the voltage recovery of DFIG wind turbines after fault clearance. Simulation results demonstrate...

  10. Mechanism of the entire overdischarge process and overdischarge-induced internal short circuit in lithium-ion batteries

    Science.gov (United States)

    Guo, Rui; Lu, Languang; Ouyang, Minggao; Feng, Xuning

    2016-01-01

    Lithium-ion batteries connected in series are prone to be overdischarged. Overdischarge results in various side effects, such as capacity degradation and internal short circuit (ISCr). However, most of previous research on the overdischarge of a cell was terminated when the cell voltage dropped to 0 V, leaving the further impacts of overdischarge unclear. This paper investigates the entire overdischarge process of large-format lithium-ion batteries by discharging the cell to −100% state of charge (SOC). A significant voltage platform is observed at approximately −12% SOC, and ISCr is detected after the cell is overdischarged when passing the platform. The scanning electron microscopy (SEM) and X-ray diffraction (XRD) results indicate that the overdischarge-induced ISCr is caused by Cu deposition on electrodes, suggesting possible Cu collector dissolution at the voltage platform near −12% SOC. A prognostic/mechanistic model considering ISCr is used to evaluate the resistance of ISCr (RISCr), the value of which decreases sharply at the beginning of ISCr formation. Inducing the ISCr by overdischarge is effective and well controlled without any mechanical deformation or the use of a foreign substance. PMID:27444934

  11. Round busbar concept for 30 nH, 1.7 kV, 10 kA IGBT non-destructive short-circuit tester

    DEFF Research Database (Denmark)

    Smirnova, Liudmila; Pyrhönen, Juha; Iannuzzo, Francesco

    2014-01-01

    and assure equal current sharing among the parallel connected devices. Achieving of a low inductance level is very challenging due to the current and voltage ratings, the presence of series and parallel protection systems and the required access for a thermal camera. The parasitic extractor Ansys Q3D is used......Design of a Non-Destructive Test (NDT) set-up for short-circuit tests of 1.7 kV, 1 kA IGBT modules is discussed in this paper. The test set-up allows achieving short-circuit current up to 10 kA. The important objective during the design of the test set-up is to minimize the parasitic inductance...... to estimate the parasitic inductances during the design. A new concept of round-shaped, low inductive busbars for an NDT set-up is proposed. Simulation results verified that both reduction of overall inductance and good uniformity in current sharing among parallel devices are achieved by utilizing a circular...

  12. Research Tool to Evaluate the Safety Response of Lithium Batteries to an Internal Short Circuit

    Energy Technology Data Exchange (ETDEWEB)

    Keyser, Matthew; Darcy, Eric; Pesaran, Ahmad

    2016-06-19

    Li-ion cells provide the highest specific energy and energy density rechargeable battery with the longest life. Many safety incidents that take place in the field originate due to an internal short that was not detectable or predictable at the point of manufacture. NREL's internal short circuit (ISC) device is capable of simulating shorts and produces consistent and reproducible results. The cell behaves normally until the ISC device is activated wherein a latent defect (i.e., built into the cell during manufacturing) gradually moves into position to create an internal short while the battery is in use, providing relevant data to verify abuse models. The ISC device is an effective tool for studying the safety features of parts of Li-ion batteries.

  13. Avoiding short circuits from zinc metal dendrites in anode by backside-plating configuration

    Science.gov (United States)

    Higashi, Shougo; Lee, Seok Woo; Lee, Jang Soo; Takechi, Kensuke; Cui, Yi

    2016-01-01

    Portable power sources and grid-scale storage both require batteries combining high energy density and low cost. Zinc metal battery systems are attractive due to the low cost of zinc and its high charge-storage capacity. However, under repeated plating and stripping, zinc metal anodes undergo a well-known problem, zinc dendrite formation, causing internal shorting. Here we show a backside-plating configuration that enables long-term cycling of zinc metal batteries without shorting. We demonstrate 800 stable cycles of nickel–zinc batteries with good power rate (20 mA cm−2, 20 C rate for our anodes). Such a backside-plating method can be applied to not only zinc metal systems but also other metal-based electrodes suffering from internal short circuits. PMID:27263471

  14. Economic Viability of Pumped-Storage Power Plants Equipped with Ternary Units and Considering Hydraulic Short-Circuit Operation

    Science.gov (United States)

    Chazarra, Manuel; Pérez-Díaz, Juan I.; García-González, Javier

    2017-04-01

    This paper analyses the economic viability of pumped-storage hydropower plants equipped with ternary units and considering hydraulic short-circuit operation. The analysed plant is assumed to participate in the day-ahead energy market and in the secondary regulation service of the Spanish power system. A deterministic day-ahead energy and reserve scheduling model is used to estimate the maximum theoretical income of the plant assuming perfect information of the next day prices and the residual demand curves of the secondary regulation reserve market. Results show that the pay-back periods with and without the hydraulic short-circuit operation are significantly lower than their expected lifetime and that the pay-back periods can be reduced with the inclusion of the hydraulic short-circuit operation.

  15. Transient Analysis of Grid-Connected Wind Turbines with DFIG After an External Short-Circuit Fault

    DEFF Research Database (Denmark)

    Sun, Tao; Chen, Zhe; Blaabjerg, Frede

    2004-01-01

    The fast development of wind power generation brings new requirements for wind turbine integration to the network. After the clearance of an external short-circuit fault, the grid-connected wind turbine should restore its normal operation with minimized power losses. This paper concentrates...... on transient analysis of variable speed wind turbines with doubly fed induction generator (DFIG) after an external short-circuit fault. A simulation model of a MW-level variable speed wind turbine with DFIG developed in PSCAD/EMTDC is presented, and the control and protection schemes are described in detail....... After the clearance of an external short-circuit fault the control schemes manage to restore the wind turbine?s normal operation, and their performances are demonstrated by simulation results both during the fault and after the clearance of the fault....

  16. Influence of Metal Transfer Stability and Shielding Gas Composition on CO and CO2 Emissions during Short-circuiting MIG/MAG Welding

    Directory of Open Access Journals (Sweden)

    Valter Alves de Meneses

    Full Text Available Abstract: Several studies have demonstrated the influence of parameters and shielding gas on metal transfer stability or on the generation of fumes in MIG/MAG welding, but little or nothing has been discussed regarding the emission of toxic and asphyxiating gases, particularly as it pertains to parameterization of the process. The purpose of this study was to analyze and evaluate the effect of manufacturing aspects of welding processes (short-circuit metal transfer stability and shielding gas composition on the gas emission levels during MIG/MAG welding (occupational health and environmental aspects. Using mixtures of Argon with CO2 and O2 and maintaining the same average current and the same weld bead volume, short-circuit welding was performed with carbon steel welding wire in open (welder’s breathing zone and confined environments. The welding voltage was adjusted to gradually vary the transfer stability. It was found that the richer the composition of the shielding gas is in CO2, the more CO and CO2 are generated by the arc. However, unlike fume emission, voltage and transfer stability had no effect on the generation of these gases. It was also found that despite the large quantity of CO and CO2 emitted by the arc, especially when using pure CO2 shielding gas, there was no high level residual concentration of CO and CO2 in or near the worker’s breathing zone, even in confined work cells.

  17. 30 CFR 77.506-1 - Electric equipment and circuits; overload and short circuit protection; minimum requirements.

    Science.gov (United States)

    2010-07-01

    ...-1 Electric equipment and circuits; overload and short circuit protection; minimum requirements... minimum requirements for protection of electric circuits and equipment of the National Electric Code, 1968. ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electric equipment and circuits; overload and...

  18. 30 CFR 75.518-1 - Electric equipment and circuits; overload and short circuit protection; minimum requirements.

    Science.gov (United States)

    2010-07-01

    ... protection against overload which does not conform to the provisions of the National Electric Code, 1968... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Electric equipment and circuits; overload and short circuit protection; minimum requirements. 75.518-1 Section 75.518-1 Mineral Resources MINE SAFETY...

  19. Fast and Accurate Icepak-PSpice Co-Simulation of IGBTs under Short-Circuit with an Advanced PSpice Model

    DEFF Research Database (Denmark)

    Wu, Rui; Iannuzzo, Francesco; Wang, Huai

    2014-01-01

    A basic problem in the IGBT short-circuit failure mechanism study is to obtain realistic temperature distribution inside the chip, which demands accurate electrical simulation to obtain power loss distribution as well as detailed IGBT geometry and material information. This paper describes an unp...

  20. Short-Circuit Fault Detection and Classification Using Empirical Wavelet Transform and Local Energy for Electric Transmission Line.

    Science.gov (United States)

    Huang, Nantian; Qi, Jiajin; Li, Fuqing; Yang, Dongfeng; Cai, Guowei; Huang, Guilin; Zheng, Jian; Li, Zhenxin

    2017-09-16

    In order to improve the classification accuracy of recognizing short-circuit faults in electric transmission lines, a novel detection and diagnosis method based on empirical wavelet transform (EWT) and local energy (LE) is proposed. First, EWT is used to deal with the original short-circuit fault signals from photoelectric voltage transformers, before the amplitude modulated-frequency modulated (AM-FM) mode with a compactly supported Fourier spectrum is extracted. Subsequently, the fault occurrence time is detected according to the modulus maxima of intrinsic mode function (IMF₂) from three-phase voltage signals processed by EWT. After this process, the feature vectors are constructed by calculating the LE of the fundamental frequency based on the three-phase voltage signals of one period after the fault occurred. Finally, the classifier based on support vector machine (SVM) which was constructed with the LE feature vectors is used to classify 10 types of short-circuit fault signals. Compared with complementary ensemble empirical mode decomposition with adaptive noise (CEEMDAN) and improved CEEMDAN methods, the new method using EWT has a better ability to present the frequency in time. The difference in the characteristics of the energy distribution in the time domain between different types of short-circuit faults can be presented by the feature vectors of LE. Together, simulation and real signals experiment demonstrate the validity and effectiveness of the new approach.

  1. Investigation of Permanent Magnet Demagnetization in Synchronous Machines during Multiple Short-Circuit Fault Conditions

    Directory of Open Access Journals (Sweden)

    Stefan Sjökvist

    2017-10-01

    Full Text Available Faults in electrical machines can vary in severity and affect different parts of the machine. This study focuses on various kinds of short-circuits on the terminal side of a generic 20 kW surface mounted permanent magnet synchronous generator and how successive faults affect the performance of the machine. The study was conducted with the commercially available finite element method software COMSOL Multiphysics ® , and two time-dependent models for demagnetization of permanent magnets were compared, one using only internal models and the other using a proprietary external function. The study is simulation based and the two models were compared to a previously experimentally verified stationary model. Results showed that the power output decreased by more than 30% after five successive faults. In addition, the no-load voltage had become unsymmetrical, which was explained by the uneven demagnetization of the permanent magnets. The permanent magnet with the lowest reduction in average remanence was decreased by 0.8%, while the highest average reduction was 23.8% in another permanent magnet. The internal simulation model was about four times faster than the external model, but slightly overestimated the demagnetization.

  2. the current susceptibility pattern of methicillin resistant ...

    African Journals Online (AJOL)

    DJFLEX

    The most notable example of the phenomenon of antibiotic resistance in Staphylococcus aureus was the emergence of methicillin resistant Staphylococcus aureus (MRSA) which was reported one year after the launch of methicillin antibiotic 4. MRSA is a bacterium responsible for difficult to treat infection in humans. The.

  3. Approaching Repetitive Short Circuit Tests on MW-Scale Power Modules by means of an Automatic Testing Setup

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Wang, Huai; Iannuzzo, Francesco

    2016-01-01

    been integrated with an advanced software tool and a semiconductor device analyzer to perform stress monitoring on the considered device under test (DUT). A case-study is included in the paper concerning a 1.7 kV/ 1 kA IGBT module, which has been tested safely up to 30,000 repetitions......An automatic testing system to perform repetitive short-circuit tests on megawatt-scale IGBT power modules is pre-sented and described in this paper, pointing out the advantages and features of such testing approach. The developed system is based on a non-destructive short-circuit tester, which has...... with no significant damage. The developed system has been demonstrated to be very helpful in performing a large number of repetition tests as required by modern testing protocols for robustness and reliability assess-ment. The software algorithm and a demonstration video are available for download....

  4. Resistant hypertension: Current status, future challenges

    Directory of Open Access Journals (Sweden)

    Niloofar Hajizadeh

    2014-01-01

    Full Text Available Resistant hypertension in adolescents is increasing in frequency and is increasingly recognized as having significant short- and long-term health consequences. It may be seen in up to 30% of all hypertensive patients cared for. Adolescents with resistant hypertension are at higher cardiovascular (CV risk due to a long history of severe hypertension complicated by other CV risk factors such as obesity. Common causes of resistant hypertension include primary aldosteronism, sleep apnea, diabetes and chronic kidney disease. Careful blood pressure (BP measurement and thorough evaluation of patients with sustained BP elevation should make a possible early diagnosis of resistant hypertension. Successful treatment requires identification and reversal of life-style factors contributing to treatment resistant and diagnosis and appropriate treatment of causes of hypertension. Improved pharmacologic therapies may offer the potential for preventing or at least ameliorating early CV disease. This review highlights these and other important issues in the evaluation and management of adolescents with resistant hypertension and provides practical guidance to the practitioners involved in caring for such patients.

  5. Effect of the depth base along the vertical on the electrical parameters of a vertical parallel silicon solar cell in open and short circuit

    Directory of Open Access Journals (Sweden)

    Gokhan Sahin

    2018-03-01

    Full Text Available This article presented a modeling study of effect of the depth base initiating on vertical parallel silicon solar cell’s photovoltaic conversion efficiency. After the resolution of the continuity equation of excess minority carriers, we calculated the electrical parameters such as the photocurrent density, the photovoltage, series resistance and shunt resistances, diffusion capacitance, electric power, fill factor and the photovoltaic conversion efficiency. We determined the maximum electric power, the operating point of the solar cell and photovoltaic conversion efficiency according to the depth z in the base. We showed that the photocurrent density decreases with the depth z. The photovoltage decreased when the depth base increases. Series and shunt resistances were deduced from electrical model and were influenced and the applied the depth base. The capacity decreased with the depth z of the base. We had studied the influence of the variation of the depth z on the electrical parameters in the base. Keywords: Depth base, Conversion efficiency, Electrical parameters, Open circuit, Short circuit

  6. The current susceptibility pattern of methicillin resistant ...

    African Journals Online (AJOL)

    The antimicrobial susceptibility pattern of methicillin-resistant Staphylococcus aureus (MRSA) from in-patients and out-patients at the University of Port Harcourt Teaching Hospital (UPTH) was studied. Fifty, S. aureus organisms were isolated from routine clinical specimens such as high vaginal, wound, urethral and ear ...

  7. Insulin resistance induced by antiretroviral drugs: Current ...

    African Journals Online (AJOL)

    Treatment with highly active antiretroviral therapy (HAART) has improved the prognosis of patients with AIDS, but it has also increased the incidence of various metabolic disorders, in particular insulin resistance accompanied by dyslipidaemia, hyperglycaemia and lipodystrophy. This is often accompanied by frank type 2 ...

  8. Current resistance issues in anti- microbial therapy

    African Journals Online (AJOL)

    Streptococcus pneumoniae is a common cause of otitis media, sinusitis, community-acquired pneumonia, meningitis and bacteraemia. Penicillin-resistant S. pneumoniae (PRSP) has emerged during the last few decades, complicating therapy for such infections. However, because of a recent change in penicillin.

  9. Current resistance issues in antimicrobial therapy | Senekal ...

    African Journals Online (AJOL)

    Continuing Medical Education. Journal Home · ABOUT THIS JOURNAL · Advanced Search · Current Issue · Archives · Journal Home > Vol 28, No 2 (2010) >. Log in or Register to get access to full text downloads.

  10. Reducing hydraulic short-circuiting in maturation ponds to maximize pathogen removal using channels and wind breaks.

    Science.gov (United States)

    Lloyd, B J; Vorkas, C A; Guganesharajah, R K

    2003-01-01

    This paper reports the impact of four sequential maturation pond interventions on the removal of thermotolerant "faecal" coliform bacteria at a full scale WSP system in tropical Colombia. Each intervention was designed to increase hydraulic retention time and was followed by continuous physico-chemical logging and meteorological monitoring, and simultaneous tracer studies to define hydraulic retention time, flow paths and dispersion. Inlet and outlet monitoring showed that, primarily due to hydraulic short-circuiting, the open maturation pond only achieved a 90% reduction in thermotolerant "faecal" coliforms. By contrast, an in-pond batch decay rate study for thermotolerant faecal coliforms showed that a 1 log (90%) reduction was achieved every 24 hours for 4 days at 26 degrees C, so that the maximum theoretical efficiency would be a 2.6 log reduction (99.7%) if hydraulic efficiency was perfect for plug flow. The second intervention was the conversion of the maturation pond to a parallel series of three open channels to attempt to control short-circuiting and convert to plug flow. The channels raised performance to 96%. The introduction of top baffles, at the end of the first and second channels, to attempt to further reduce the effect of surface and sub-surface flow on short-circuiting, actually reduced performance to 92.64%, and were removed. The final intervention, a 2.1 m high wind break around the maturation channels raised efficiency to 98.13%; this performance is almost a half log (0.47) greater than the efficiency (95.1%) predicted from Marais' equation for a completely mixed reactor, and 0.77 log greater than recorded in the open pond. The results have fundamental implications for improving WSP efficiency, for meeting re-use guidelines, for savings in land area and improvement of design of WSPs; they also highlight short-comings in the indiscriminate use of the Marais design equation for faecal coliform removal.

  11. Matlab/Simulink Implementation of Wave-based Models for Microstrip Structures utilizing Short-circuited and Opened Stubs

    Directory of Open Access Journals (Sweden)

    Biljana P. Stošić

    2011-12-01

    Full Text Available This paper describes modeling and analyzing procedures for microstrip filters based on use of one-dimensional wave digital approach. Different filter structures are observed. One filter is based on quarter-wave length short-circuited stubs and connecting transmission lines. The other one is based on cross-junction opened stubs. Frequency responses are obtained by direct analysis of the block-based networks formed in Simulink toolbox of MATLAB environment. This wave-based method allows an accurate and efficient analysis of different microwave structures.

  12. Fast-responding short circuit protection system with self-reset for use in circuit supplied by DC power

    Science.gov (United States)

    Burns, Bradley M. (Inventor); Blalock, Norman N. (Inventor)

    2011-01-01

    A short circuit protection system includes an inductor, a switch, a voltage sensing circuit, and a controller. The switch and inductor are electrically coupled to be in series with one another. A voltage sensing circuit is coupled across the switch and the inductor. A controller, coupled to the voltage sensing circuit and the switch, opens the switch when a voltage at the output terminal of the inductor transitions from above a threshold voltage to below the threshold voltage. The controller closes the switch when the voltage at the output terminal of the inductor transitions from below the threshold voltage to above the threshold voltage.

  13. A geometric approach for fault detection and isolation of stator short circuit failure in a single asynchronous machine

    KAUST Repository

    Khelouat, Samir

    2012-06-01

    This paper deals with the problem of detection and isolation of stator short-circuit failure in a single asynchronous machine using a geometric approach. After recalling the basis of the geometric approach for fault detection and isolation in nonlinear systems, we will study some structural properties which are fault detectability and isolation fault filter existence. We will then design filters for residual generation. We will consider two approaches: a two-filters structure and a single filter structure, both aiming at generating residuals which are sensitive to one fault and insensitive to the other faults. Some numerical tests will be presented to illustrate the efficiency of the method.

  14. Effect of short circuited DC link capacitor of an AC–DC–AC inverter on the performance of induction motor

    Directory of Open Access Journals (Sweden)

    Hadeed Ahmed Sher

    2016-07-01

    Full Text Available Induction motors are widely used in industrial power plants due to their robustness, reliability and high performance under variable operating conditions in the electrical power system. Modern industrial progress is dependent on these ruggedly constructed induction motors. Almost every sophisticated process of the industry is based on induction motors. Most of these motors are controlled by means of inverters that change the line frequency. The change in parameters of inverter makes it possible to control the motor according to the design requirements. The reliability of inverter based motor control is an important issue for industrial applications and therefore, it becomes very vital for design engineers to have comprehensive analysis of the inverter fed induction machine. This paper investigates one of the faults that may occur on the DC link of an inverter fed induction motor. The effect of the capacitor short circuit is presented in this paper. It also deals with the effects of short circuited capacitor on freewheeling diode. DC link capacitors are well designed and even the probability of capacitor failure is high, it is always a rare case if they puncture, however this analysis will add to the reliability of the induction machine under variable operating condition.

  15. Detection of inter-turn short-circuit at start-up of induction machine based on torque analysis

    Science.gov (United States)

    Pietrowski, Wojciech; Górny, Konrad

    2017-12-01

    Recently, interest in new diagnostics methods in a field of induction machines was observed. Research presented in the paper shows the diagnostics of induction machine based on torque pulsation, under inter-turn short-circuit, during start-up of a machine. In the paper three numerical techniques were used: finite element analysis, signal analysis and artificial neural networks (ANN). The elaborated numerical model of faulty machine consists of field, circuit and motion equations. Voltage excited supply allowed to determine the torque waveform during start-up. The inter-turn short-circuit was treated as a galvanic connection between two points of the stator winding. The waveforms were calculated for different amounts of shorted-turns from 0 to 55. Due to the non-stationary waveforms a wavelet packet decomposition was used to perform an analysis of the torque. The obtained results of analysis were used as input vector for ANN. The response of the neural network was the number of shorted-turns in the stator winding. Special attention was paid to compare response of general regression neural network (GRNN) and multi-layer perceptron neural network (MLP). Based on the results of the research, the efficiency of the developed algorithm can be inferred.

  16. Robust Diagnosis Method Based on Parameter Estimation for an Interturn Short-Circuit Fault in Multipole PMSM under High-Speed Operation.

    Science.gov (United States)

    Lee, Jewon; Moon, Seokbae; Jeong, Hyeyun; Kim, Sang Woo

    2015-11-20

    This paper proposes a diagnosis method for a multipole permanent magnet synchronous motor (PMSM) under an interturn short circuit fault. Previous works in this area have suffered from the uncertainties of the PMSM parameters, which can lead to misdiagnosis. The proposed method estimates the q-axis inductance (Lq) of the faulty PMSM to solve this problem. The proposed method also estimates the faulty phase and the value of G, which serves as an index of the severity of the fault. The q-axis current is used to estimate the faulty phase, the values of G and Lq. For this reason, two open-loop observers and an optimization method based on a particle-swarm are implemented. The q-axis current of a healthy PMSM is estimated by the open-loop observer with the parameters of a healthy PMSM. The Lq estimation significantly compensates for the estimation errors in high-speed operation. The experimental results demonstrate that the proposed method can estimate the faulty phase, G, and Lq besides exhibiting robustness against parameter uncertainties.

  17. Robust Diagnosis Method Based on Parameter Estimation for an Interturn Short-Circuit Fault in Multipole PMSM under High-Speed Operation

    Directory of Open Access Journals (Sweden)

    Jewon Lee

    2015-11-01

    Full Text Available This paper proposes a diagnosis method for a multipole permanent magnet synchronous motor (PMSM under an interturn short circuit fault. Previous works in this area have suffered from the uncertainties of the PMSM parameters, which can lead to misdiagnosis. The proposed method estimates the q-axis inductance (Lq of the faulty PMSM to solve this problem. The proposed method also estimates the faulty phase and the value of G, which serves as an index of the severity of the fault. The q-axis current is used to estimate the faulty phase, the values of G and Lq. For this reason, two open-loop observers and an optimization method based on a particle-swarm are implemented. The q-axis current of a healthy PMSM is estimated by the open-loop observer with the parameters of a healthy PMSM. The Lq estimation significantly compensates for the estimation errors in high-speed operation. The experimental results demonstrate that the proposed method can estimate the faulty phase, G, and Lq besides exhibiting robustness against parameter uncertainties.

  18. Ground-Fault Characteristic Analysis of Grid-Connected Photovoltaic Stations with Neutral Grounding Resistance

    Directory of Open Access Journals (Sweden)

    Zheng Li

    2017-11-01

    Full Text Available A centralized grid-connected photovoltaic (PV station is a widely adopted method of neutral grounding using resistance, which can potentially make pre-existing protection systems invalid and threaten the safety of power grids. Therefore, studying the fault characteristics of grid-connected PV systems and their impact on power-grid protection is of great importance. Based on an analysis of the grid structure of a grid-connected PV system and of the low-voltage ride-through control characteristics of a photovoltaic power supply, this paper proposes a short-circuit calculation model and a fault-calculation method for this kind of system. With respect to the change of system parameters, particularly the resistance connected to the neutral point, and the possible impact on protective actions, this paper achieves the general rule of short-circuit current characteristics through a simulation, which provides a reference for devising protection configurations.

  19. Analysis of simultaneous unbalanced short circuit and open conductor faults in power systems with untransposed lines and six-phase sections

    Directory of Open Access Journals (Sweden)

    Karim Hassan Youssef

    2016-03-01

    Full Text Available The paper introduces a generalized method for analysis of multiple, simultaneous short circuit, open circuit, and open circuit falling conductor faults in mixed three-phase and six-phase power systems with untransposed lines. The method is systematic and suitable for all types of faults, any number of simultaneous faults, and any number of phases. Calculation of all network unbalanced voltages and currents during faults is done in one straightforward step. Coupling among sequence networks in untransposed transmission lines is accounted for. Coupling between the three-sequence networks of the three-phase part and the six-sequence networks of six-phase part is also derived. The method is applied also for transient stability study of mixed three-phase and six-phase power systems during any type of faults. Detailed derivation of the governing equations in each part is presented. Simulation results on the IEEE 300-bus system and the IEEE 30-bus system are given to validate the proposed method.

  20. Absorption Characterization of Mn-Zr-Substituted La-Sr Hexaferrite Using Open-Circuit and Short-Circuit Approaches in 8.2-18 GHz Frequency Range

    Science.gov (United States)

    Narang, Sukhleen Bindra; Kaur, Pawandeep; Bahel, Shalini; Pubby, Kunal

    2018-01-01

    The present study reports on the microwave absorption characterization of Mn2+-Zr4+ substituted lanthanum strontium ferrites, Sr0.85La0.15(MnZr) x Fe12-2 x O19, where x = 0.0, 0.25, 0.50, 0.75 and 1.0 in the X- and Ku-band. The synthesized ferrites are characterized with regard to their electromagnetic properties such as complex permittivity ( {ɛ^' - jɛ^'' ) and complex permeability ( {μ^' - jμ^'' ) using vector network analysis in the 8.2-18 GHz frequency range. Real and imaginary parts of permittivity decrease with the increase in Mn-Zr concentration due to a reduction in electron hopping conduction and eddy current losses, respectively. Microwave permeability spectra are also affected by the doping. The amplitude of magnetic loss peak increases with the increase in doping except for the x = 1.0 composition. Two commonly used approaches, open-circuit and short-circuit, have been employed for the absorption analysis. The difference in the results of these two techniques is justified on the basis of the reflection mechanism. The presented experimental findings underline the potential of the synthesized compositions with Mn-Zr concentrations x = 0.25, 0.5 and 0.75 in the suppression of electromagnetic reflections and radar signatures.

  1. Short-Circuit Degradation of 10-kV 10-A SiC MOSFET

    DEFF Research Database (Denmark)

    Eni, Emanuel-Petre; Beczkowski, Szymon; Munk-Nielsen, Stig

    2017-01-01

    leads to an overall increase in device on-state resistance at the end of the degradation study. Thermal simulation show that the surface aluminum metalization reached its melting temperature and the top part of the device reaches temperatures above the rated junction temperature. Scanning electron...... microscope (SEM) investigation shows aluminum reconstruction and cavities at the contact interface between the aluminum surface metalization and source contacts....

  2. Analysis of Short-circuit and Protection Failure Risk Considering Random Output of Distributed Photovoltaics

    Science.gov (United States)

    Da, Yao; Huan, Zhang; Wei, Deng

    2017-05-01

    Distributed photovoltaics (DPV) will increase or shunt the fault current as a branch of the power supply. The random outputs of DPV will also cause a random distribution of fault current, while the breaking capacity of the breaker and the setting value of the current protection is pre-set value, and cannot flexibly change, so DPV will bring a certain degree of influence on the breaking margin and the sensitivity of protection. This paper makes probability distribution calculating model of fault current containing DPV, and takes IEEE 33-node system as an example, simulated the probability distribution of fault current at different penetration of DPV. Finally, from the two indicators of the breaking margin of breaker and the sensitivity of protection, analysed the protection failure risk after the access of DPV.

  3. Model-based fault diagnosis approach on external short circuit of lithium-ion battery used in electric vehicles

    International Nuclear Information System (INIS)

    Chen, Zeyu; Xiong, Rui; Tian, Jinpeng; Shang, Xiong; Lu, Jiahuan

    2016-01-01

    Highlights: • The characteristics of ESC fault of lithium-ion battery are investigated experimentally. • The proposed method to simulate the electrical behavior of ESC fault is viable. • Ten parameters in the presented fault model were optimized using a DPSO algorithm. • A two-layer model-based fault diagnosis approach for battery ESC is proposed. • The effective and robustness of the proposed algorithm has been evaluated. - Abstract: This study investigates the external short circuit (ESC) fault characteristics of lithium-ion battery experimentally. An experiment platform is established and the ESC tests are implemented on ten 18650-type lithium cells considering different state-of-charges (SOCs). Based on the experiment results, several efforts have been made. (1) The ESC process can be divided into two periods and the electrical and thermal behaviors within these two periods are analyzed. (2) A modified first-order RC model is employed to simulate the electrical behavior of the lithium cell in the ESC fault process. The model parameters are re-identified by a dynamic-neighborhood particle swarm optimization algorithm. (3) A two-layer model-based ESC fault diagnosis algorithm is proposed. The first layer conducts preliminary fault detection and the second layer gives a precise model-based diagnosis. Four new cells are short-circuited to evaluate the proposed algorithm. It shows that the ESC fault can be diagnosed within 5 s, the error between the model and measured data is less than 0.36 V. The effectiveness of the fault diagnosis algorithm is not sensitive to the precision of battery SOC. The proposed algorithm can still make the correct diagnosis even if there is 10% error in SOC estimation.

  4. Nonlinear compensation to enhance the input dynamic range in analog optical fiber links for the high current short circuit test

    International Nuclear Information System (INIS)

    Rodriguez, Joaquin; Garduno, Raul; Velazquez, Jose; Montero, Julio

    2010-01-01

    Due to their galvanic insulation and EMI immunity properties, optical fiber links have been used in the transmitter–receiver system of an analog voltage measuring system at a high-power mid-voltage testing laboratory with a highly aggressive EMI environment. This paper introduces the application of a nonlinear compensation to limit the voltage range at the input of a voltage-controlled oscillator, which is used to produce the pulsed frequency modulation needed to transmit the analog signals over the optical fiber links. The proposed dynamic range compensation system is based on nonlinear circuits to accommodate the input range of the voltage-controlled oscillator. This approach increases the transient signal handling capabilities of the measuring system. This work demonstrates that the nonlinear compensated optical fiber approach yields a unique, electrically isolated, lightning-proof analog data transmission system, for remote measuring systems in the highly aggressive EMI environment of high-power test laboratories

  5. Functionalized carbon nanotube doping of P3HT:PCBM photovoltaic devices for enhancing short circuit current and efficiency

    Directory of Open Access Journals (Sweden)

    Rohit Bhatia

    2017-03-01

    Full Text Available We have successfully functionalized multiwalled carbon nanotubes (MWCNTs using nitrene approach employing the two aryl azides as a precursor for nitrene generation. The dispersion of functionalized MWCNTs has been enhanced in various organic solvents. These functionalized MWCNTs have been successfully doped in various concentrations in the bulk heterojunction (BHJ organic photovoltaic (OPV cells with a poly (3-hexyl thiophene (P3HT and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM photoactive blended layer. The incorporation of MWCNTs with aryl functional groups, in active the layer, results in enhanced performance with respect to a reference cell. The maximum power conversion efficiency of 1.86% is achieved with adduct I while in the case of adduct II it gets double to 2.0% in comparison with a reference cell. This improvement in the device performance is attributed to enhanced exciton dissociation and improved charge transport properties due to the formation of a nanotube percolation network in the photoactive composite layer.

  6. Protection during overvoltage and short circuits in electrical devices. Comments on DIN VDE 0100-430 and DIN VDE 0298-4. 2. ed.; Schutz bei Ueberlast und Kurzschluss in elektrischen Anlagen. Erlaeuterungen zu DIN VDE 0100-430 und DIN VDE 0298-4

    Energy Technology Data Exchange (ETDEWEB)

    Nienhaus, H.; Spindler, U.; Vogt, D.

    2006-07-01

    The new DIN VDI 0100 part 430 provides a high degree of protection against overvoltages. An enclosed tables of maximum current loads shows possible reserves in supply lines. An investigation showed that adjustable circuit breakers ensure 100% availability as well as maximum protection. They also offer optimum protection in case of short circuits owing to the minimisation of shut-off times. Current-limiting circuit breakers also facilitate power systems projecting. (GL).

  7. Model for the resistive critical current transition in composite superconductors

    International Nuclear Information System (INIS)

    Warnes, W.H.

    1988-01-01

    Much of the research investigating technological type-II superconducting composites relies on the measurement of the resistive critical current transition. We have developed a model for the resistive transition which improves on older models by allowing for the very different nature of monofilamentary and multifilamentary composite structures. The monofilamentary model allows for axial current flow around critical current weak links in the superconducting filament. The multifilamentary model incorporates an additional radial current transfer between neighboring filaments. The development of both models is presented. It is shown that the models are useful for extracting more information from the experimental data than was formerly possible. Specific information obtainable from the experimental voltage-current characteristic includes the distribution of critical currents in the composite, the average critical current of the distribution, the range of critical currents in the composite, the field and temperature dependence of the distribution, and the fraction of the composite dissipating energy in flux flow at any current. This additional information about the distribution of critical currents may be helpful in leading toward a better understanding of flux pinning in technological superconductors. Comparison of the models with several experiments is given and shown to be in reasonable agreement. Implications of the models for the measurement of critical currents in technological composites is presented and discussed with reference to basic flux pinning studies in such composites

  8. Detection of stator winding faults in induction motors using three-phase current monitoring.

    Science.gov (United States)

    Sharifi, Rasool; Ebrahimi, Mohammad

    2011-01-01

    The objective of this paper is to propose a new method for the detection of inter-turn short circuits in the stator windings of induction motors. In the previous reported methods, the supply voltage unbalance was the major difficulty, and this was solved mostly based on the sequence component impedance or current which are difficult to implement. Some other methods essentially are included in the offline methods. The proposed method is based on the motor current signature analysis and utilizes three phase current spectra to overcome the mentioned problem. Simulation results indicate that under healthy conditions, the rotor slot harmonics have the same magnitude in three phase currents, while under even 1 turn (0.3%) short circuit condition they differ from each other. Although the magnitude of these harmonics depends on the level of unbalanced voltage, they have the same magnitude in three phases in these conditions. Experiments performed under various load, fault, and supply voltage conditions validate the simulation results and demonstrate the effectiveness of the proposed technique. It is shown that the detection of resistive slight short circuits, without sensitivity to supply voltage unbalance is possible. Copyright © 2010 ISA. Published by Elsevier Ltd. All rights reserved.

  9. Mycoplasma genitalium infections: current treatment options and resistance issues

    Directory of Open Access Journals (Sweden)

    Sethi S

    2017-09-01

    Full Text Available Sunil Sethi, Kamran Zaman, Neha Jain Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India Abstract: Mycoplasma genitalium is one of the important causes of non-gonococcal urethritis. Rising incidence and emerging antimicrobial resistance are a major concern these days. The poor clinical outcomes with doxycycline therapy led to the use of azithromycin as the primary drug of choice. Single-dose azithromycin regimen over a period of time was changed to extended regimen following studies showing better clinical cures and less risk of resistance development. However, emerging macrolide resistance, either due to transmission of resistance or drug pressure has further worsened the management of this infection. The issues of drug resistance and treatment failures also exist in cases of M. genitalium infection. At present, the emergence of multidrug-resistant (MDR M. genitalium strains is an alarming sign for its treatment and the associated public health impact due to its complications. However, newer drugs like pristinamycin, solithromycin, sitafloxacin, and others have shown a hope for the clinical cure, but need further clinical trials to optimize the therapeutic dosing schedules and formulate appropriate treatment regimens. Rampant and inappropriate use of these newer drugs will further sabotage future attempts to manage MDR strains. There is currently a need to formulate diagnostic algorithms and etiology-based treatment regimens rather than the syndromic approach, preferably using combination therapy instead of a monotherapy. Awareness about the current guidelines and recommended treatment regimens among clinicians and local practitioners is of utmost importance. Antimicrobial resistance testing and global surveillance are required to assess the efficacy of current treatment regimens and for guiding future research for the early detection and management of MDR M. genitalium infections

  10. A Short-Circuit Safe Operation Area Identification Criterion for SiC MOSFET Power Modules

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Luo, Haoze

    2017-01-01

    -circuit-current-based criterion; and 2) the gate-voltage-based criterion. The applicability of these two criteria makes possible the SCSOA evaluation of SiC MOSFETs with some safety margins in order to avoid unnecessary failures during their SCSOA characterization. SiC MOSFET power modules from two different manufacturers...

  11. Stability evaluation of short-circuiting gas metal arc welding based on ensemble empirical mode decomposition

    Science.gov (United States)

    Huang, Yong; Wang, Kehong; Zhou, Zhilan; Zhou, Xiaoxiao; Fang, Jimi

    2017-03-01

    The arc of gas metal arc welding (GMAW) contains abundant information about its stability and droplet transition, which can be effectively characterized by extracting the arc electrical signals. In this study, ensemble empirical mode decomposition (EEMD) was used to evaluate the stability of electrical current signals. The welding electrical signals were first decomposed by EEMD, and then transformed to a Hilbert-Huang spectrum and a marginal spectrum. The marginal spectrum is an approximate distribution of amplitude with frequency of signals, and can be described by a marginal index. Analysis of various welding process parameters showed that the marginal index of current signals increased when the welding process was more stable, and vice versa. Thus EEMD combined with the marginal index can effectively uncover the stability and droplet transition of GMAW.

  12. Current status of insecticide resistance among malaria vectors in Kenya.

    Science.gov (United States)

    Ondeto, Benyl M; Nyundo, Christopher; Kamau, Luna; Muriu, Simon M; Mwangangi, Joseph M; Njagi, Kiambo; Mathenge, Evan M; Ochanda, Horace; Mbogo, Charles M

    2017-09-19

    Insecticide resistance has emerged as one of the major challenges facing National Malaria Control Programmes in Africa. A well-coordinated national database on insecticide resistance (IRBase) can facilitate the development of effective strategies for managing insecticide resistance and sustaining the effectiveness of chemical-based vector control measures. The aim of this study was to assemble a database on the current status of insecticide resistance among malaria vectors in Kenya. Data was obtained from published literature through PubMed, HINARI and Google Scholar searches and unpublished literature from government reports, research institutions reports and malaria control programme reports. Each data source was assigned a unique identification code and entered into Microsoft Excel 2010 datasheets. Base maps on the distribution of insecticide resistance and resistance mechanisms among malaria vectors in Kenya were generated using ArcGIS Desktop 10.1 (ESRI, Redlands, CA, USA). Insecticide resistance status among the major malaria vectors in Kenya was reported in all the four classes of insecticides including pyrethroids, carbamates, organochlorines and organophosphates. Resistance to pyrethroids has been detected in Anopheles gambiae (s.s.), An. arabiensis and An. funestus (s.s.) while resistance to carbamates was limited to An. gambiae (s.s.) and An. arabiensis. Resistance to the organochlorine was reported in An. gambiae (s.s.) and An. funestus (s.s.) while resistance to organophosphates was reported in An. gambiae (s.l.) only. The mechanisms of insecticide resistance among malaria vectors reported include the kdr mutations (L 1014S and L 1014F) and elevated activity in carboxylesterase, glutathione S-transferases (GST) and monooxygenases. The kdr mutations L 1014S and L 1014F were detected in An. gambiae (s.s.) and An. arabiensis populations. Elevated activity of monooxygenases has been detected in both An. arabiensis and An. gambiae (s.s.) populations while

  13. Erlotinib resistance in Lung Cancer: Current Progress and Future Perspectives

    Directory of Open Access Journals (Sweden)

    Joy eTang

    2013-02-01

    Full Text Available Lung cancer is the most common cancer in the world. Despite modern advancements in surgeries, chemotherapies and radiotherapies over the past few years, lung cancer still remains a very difficult disease to treat. This has left the death rate from lung cancer victims largely unchanged throughout the past few decades. A key cause for the high mortality rate is the drug resistance that builds up for patients being currently treated with the chemotherapeutic agents. Although certain chemotherapeutic agents may initially effectively treat lung cancer patients, there is a high probability that there will be a reoccurrence of the cancer after the patient develops resistance to the drug. Erlotinib, the epidermal growth factor receptor (EGFR-targeting tyrosine kinase inhibitor, has been approved for localized as well as metastatic non-small cell lung cancer where it seems to be more effective in patients with EGFR mutations. Resistance to erlotinib is a common observation in clinics and this review details our current knowledge on the subject. We discuss the causes of such resistance as well as innovative research to overcome it. Evidently, new chemotherapy strategies are desperately needed in order to better treat lung cancer patients. Current research is investigating alternative treatment plans to enhance the chemotherapy that is already offered. Better insight into the molecular mechanisms behind combination therapy pathways and even single molecular pathways may help improve the efficacy of the current treatment options.

  14. Fast Calculation Model and Theoretical Analysis of Rotor Unbalanced Magnetic Pull for Inter-Turn Short Circuit of Field Windings of Non-Salient Pole Generators

    Directory of Open Access Journals (Sweden)

    Guangtao Zhang

    2017-05-01

    Full Text Available Inter-turn short circuit of field windings (ISCFW may cause the field current of a generator to increase, output reactive power to decrease, and unit vibration to intensify, seriously affecting its safe and stable operation. Full integration of mechanical and electrical characteristics can improve the sensitivity of online monitoring, and detect the early embryonic period fault of small turns. This paper studies the calculations and variations of unbalanced magnetic pull (UMP, of which the excitation source of rotor vibration is the basis and key to online fault monitoring. In grid load operation, ISCFW are first calculated with the multi-loop method, so as to obtain the numerical solutions of the stator and the rotor currents during the fault. Next, the air-gap magnetic field of the ISCFW is analyzed according to the actual composition modes of the motor loops in the fault, so as to obtain the analytic expressions of the air-gap magnetic motive force (MMF and magnetic density. The UMP of the rotor is obtained by solving the integral of the Maxwell stress. The correctness of the electric quantity calculation is verified by the ISCFW experiment, conducted in a one pair-pole non-salient pole model machine. On this basis, comparing the simulation analysis with the calculation results of the model in this paper not only verifies the accuracy of the electromagnetic force calculation, but also proves that the latter has the advantages of a short time consumption and high efficiency. Finally, the influencing factors and variation law of UMP are analyzed by means of an analytic model. This develops a base for the online monitoring of ISCFW with the integration of mechanical and electrical information.

  15. Fluconazole resistance in Candida species: a current perspective

    Directory of Open Access Journals (Sweden)

    Berkow EL

    2017-07-01

    Full Text Available Elizabeth L Berkow, Shawn R Lockhart Mycotic Diseases Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA Abstract: Candida albicans and the emerging non-albicans Candida spp. have significant clinical relevance among many patient populations. Current treatment guidelines include fluconazole as a primary therapeutic option for the treatment of these infections, but it is only fungistatic against Candida spp. and both inherent and acquired resistance to fluconazole have been reported. Such mechanisms of resistance include increased drug efflux, alteration or increase in the drug target, and development of compensatory pathways for producing the target sterol, ergosterol. While many mechanisms of resistance observed in C. albicans are also found in the non-albicans species, there are also important and unexpected differences between species. Furthermore, mechanisms of fluconazole resistance in emerging Candida spp., including the global health threat Candida auris, are largely unknown. In order to preserve the utility of one of our fundamental antifungal drugs, fluconazole, it is essential that we fully appreciate the manner by which Candida spp. manifest resistance to it. Keywords: Candida, fluconazole resistance, ERG11, drug efflux, ergosterol

  16. Modelling Li-ion cell thermal runaway triggered by an internal short circuit device using an efficiency factor and Arrhenius formulations

    DEFF Research Database (Denmark)

    Coman, Paul Tiberiu; Darcy, Eric; Veje, Christian

    2017-01-01

    This paper presents a novel model for analyzing the thermal runaway in Li-ion battery cells with an internal short circuit device implanted in the cell. The model is constructed using Arrhenius formulations for representing the self-heating chemical reactions and the State of Charge. The model...

  17. Resistive current limiter with high-temperature superconductors. Final report

    International Nuclear Information System (INIS)

    Schubert, M.

    1995-12-01

    Fundamental results of the possibility of using high temperature superconductors (HTSC) in resistive fault current limiters are discussed. Measurement of the homogeneity of BSCCO-powder-in-tube materials were made. In addition, investigations of the transition from superconducting to normalconducting state under AC-current conditions were carried out. Based on these results, simulations of HTSC-materials on ceramic substrate were made and recent results are presented. Important results of the investigations are: 1. Current-limiting without external trigger only possible when the critical current density of HTSC exceeds 10 4 A/cm 2 . 2. Inhomogeneities sometimes cause problems with local destruction. This can be solved by parallel-elements or external trigger. 3. Fast current-limiting causes overvoltages which can be reduced by using parallel-elements. (orig.) [de

  18. On-Line Detection of Coil Inter-Turn Short Circuit Faults in Dual-Redundancy Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Yiguang Chen

    2018-03-01

    Full Text Available In the aerospace and military fields, with high reliability requirements, the dual-redundancy permanent magnet synchronous motor (DRPMSM with weak thermal coupling and no electromagnetic coupling is needed. A common fault in the DRPMSM is the inter-turn short circuit fault (ISCF. However, research on how to diagnose ISCF and the set of faulty windings in the DRPMSM is lacking. In this paper, the structure of the DRPMSM is analyzed and mathematical models of the motor under normal and faulty conditions are established. Then an on-line ISCF detection scheme, which depends on the running modes of the DRPMSM and the average values for the difference of the d-axis voltages between two sets of windings in the latest 20 sampling periods, is proposed. The main contributions of this paper are to analyze the calculation for the inductance of each part of the stator windings and propose the on-line diagnosis method of the ISCF under various operating conditions. The simulation and experimental results show that the proposed method can quickly and effectively diagnose ISCF and determine the set of faulty windings of the DRPMSM.

  19. Impact of hydroelectric installations on the morphology's short-circuited reaches of the Durance and the Verdon Rivers

    International Nuclear Information System (INIS)

    Lefort, Philippe; Chapuis, Margot

    2012-01-01

    Attenuation of flood peaks by the reservoirs of Serre Poncon and along the Verdon River, and diversions of the Durance River's flow in the industrial canal significantly modify the flow regime in the short-circuited beds. Upstream inflow of gravel materials is decreased, bed-load transport is significantly reduced, channels' mobility is atrophied, or becomes even nonexistent. The vegetation impact leads then to an obstruction of the braided channel, the rare occurrence of high flows is not able to prevent. Clearing the bed has been and stays an efficient response to the vegetation encroachment, and a necessary condition to maintain the discharge capacity during high flow, the originality and the diversity of the natural landforms. The loss of mobility is also due to bed-load transport's interruption through dams, but even more to the past gravel extractions and to weirs that sustain low flow: bed-load transport restoration through dams, sedimentary recharge of the bed with gravels coming from lateral terraces and increasing of high flows intensity will lead to a minimal required mobility. (authors)

  20. Short-Circuit Fault Tolerant Control of a Wind Turbine Driven Induction Generator Based on Sliding Mode Observers

    Directory of Open Access Journals (Sweden)

    Takwa Sellami

    2017-10-01

    Full Text Available The installed energy production capacity of wind turbines is growing intensely on a global scale, making the reliability of wind turbine subsystems of greater significance. However, many faults like Inter-Turn Short-Circuit (ITSC may affect the turbine generator and quickly lead to a decline in supplied power quality. In this framework, this paper proposes a Sliding Mode Observer (SMO-based Fault Tolerant Control (FTC scheme for Induction Generator (IG-based variable-speed grid-connected wind turbines. First, the dynamic models of the wind turbine subsystems were developed. The control schemes were elaborated based on the Maximum Power Point Tracking (MPPT method and Indirect Rotor Flux Oriented Control (IRFOC method. The grid control was also established by regulating the active and reactive powers. The performance of the wind turbine system and the stability of injected power to the grid were hence analyzed under both healthy and faulty conditions. The robust developed SMO-based Fault Detection and Isolation (FDI scheme was proved to be fast and efficient for ITSC detection and localization.Afterwards, SMO were involved in scheming the FTC technique. Accordingly, simulation results assert the efficacy of the proposed ITSC FTC method for variable-speed wind turbines with faulty IG in protecting the subsystems from damage and ensuring continuous connection of the wind turbine to the grid during ITSC faults, hence maintaining power quality.

  1. KNOWLEDGE TRANSFER AND LEARNING: PROBLEMS OF KNOWLEDGE TRANSFER ASSOCIATED WITH TRYING TO SHORT-CIRCUIT THE LEARNING CYCLE

    Directory of Open Access Journals (Sweden)

    Sue Newell

    2006-11-01

    Full Text Available Knowledge is considered to be a key organizational resource in the 21st century and the knowledge management ‘movement’ has alerted organizations to the fact that they should more strategically exploit their knowledge assets. Companies are thus lured by the suggestion that they can gain competitive advantage by the more astute management of their knowledge base and in particular, by the transfer of knowledge across individuals, groups and organizational units, using IT to accomplish this. In this paper, we reflect on this common view of knowledge transfer. More specifically, we question an implication of this view - essentially the possibility of short-circuiting the learning cycle, so that individuals do not have to rely on their personal or shared experiences to identify better practices, but can learn from the codified lessons of others in IT systems. More importantly, we consider the characteristics of knowledge – that knowledge is distributed, ambiguous and disruptive – that makes its transfer highly problematic. Drawing on case research, we relate this to the learning cycle (Kolb 1984 and thereby identify barriers to knowledge transfer. We conclude by considering ways of overcoming these barriers by emphasizing the importance of social systems alongside technical systems.

  2. Arrester Resistive Current Measuring System Based on Heterogeneous Network

    Science.gov (United States)

    Zhang, Yun Hua; Li, Zai Lin; Yuan, Feng; Hou Pan, Feng; Guo, Zhan Nan; Han, Yue

    2018-03-01

    Metal Oxide Arrester (MOA) suffers from aging and poor insulation due to long-term impulse voltage and environmental impact, and the value and variation tendency of resistive current can reflect the health conditions of MOA. The common wired MOA detection need to use long cables, which is complicated to operate, and that wireless measurement methods are facing the problems of poor data synchronization and instability. Therefore a novel synchronous measurement system of arrester current resistive based on heterogeneous network is proposed, which simplifies the calculation process and improves synchronization, accuracy and stability and of the measuring system. This system combines LoRa wireless network, high speed wireless personal area network and the process layer communication, and realizes the detection of arrester working condition. Field test data shows that the system has the characteristics of high accuracy, strong anti-interference ability and good synchronization, which plays an important role in ensuring the stable operation of the power grid.

  3. Analisa Penggunaan Superconducting Fault Current Limiter (SFCL Untuk Melindungi Peralatan di PT Pindo Deli

    Directory of Open Access Journals (Sweden)

    Yohanes Sabriant Widyo Utomo

    2015-12-01

    Full Text Available Increas demand load and power capacity requirement at PT Pindo Deli then the short circuit current that occur will be greater. this can cause damage to electrical equipment located around the point of interrupting and resulting failure of the electrical system in power distribution. from the analysis of the three phase short circuit current 1/2 cycle seen that the bus 1 exceeds the peak breacing  asimetry equipment.  Where breacing peak bus asymetri 1 was 43.88 kA. While the peak of 3-phase  short circuit on the bus 1 is 47.98 kA.  To protect the equipment and the entire electrical system in PT Pindo Deli would require  the use of Superconducting Fault Current Limiter (SFCL that will be placed on buses that  exceed or approach the critical point. There are two kinds of Superconducting Fault Current Limiter that type of resistive and saturated iron core. In this final project SFCL used  is a hybrid resistive Superconducting Fault Current Limiting. By using a hybrid resistive  SFCL then flow disturbance will quickly be reduced by utilizing the reactance of Current  Limiting Reactor (CLR that is connected parallel with superonductor So as to secure all the equipment and electrical systems of a total blackout. After determination of Superconducting Fault Current Limiter setting the overcurrent relay coordination to determine whether existing coordination setting in accordance with the conditions there.  The coordination displayed using the curve Current Time Curve (TCC.

  4. Erlotinib Resistance in Lung Cancer: Current Progress and Future Perspectives

    OpenAIRE

    Tang, Joy; Salama, Rasha; Gadgeel, Shirish M.; Sarkar, Fazlul H.; Ahmad, Aamir

    2013-01-01

    Lung cancer is the most common cancer in the world. Despite modern advancements in surgeries, chemotherapies, and radiotherapies over the past few years, lung cancer still remains a very difficult disease to treat. This has left the death rate from lung cancer victims largely unchanged throughout the past few decades. A key cause for the high mortality rate is the drug resistance that builds up for patients being currently treated with the chemotherapeutic agents. Although certain chemotherap...

  5. Global Current Circuit Structure in a Resistive Pulsar Magnetosphere Model

    Science.gov (United States)

    Kato, Yugo. E.

    2017-12-01

    Pulsar magnetospheres have strong magnetic fields and large amounts of plasma. The structures of these magnetospheres are studied using force-free electrodynamics. To understand pulsar magnetospheres, discussions must include their outer region. However, force-free electrodynamics is limited in it does not handle dissipation. Therefore, a resistive pulsar magnetic field model is needed. To break the ideal magnetohydrodynamic (MHD) condition E\\cdot B=0, Ohm’s law is used. This work introduces resistivity depending upon the distance from the star and obtain a self-consistent steady state by time integration. Poloidal current circuits form in the magnetosphere while the toroidal magnetic field region expands beyond the light cylinder and the Poynting flux radiation appears. High electric resistivity causes a large space scale poloidal current circuit and the magnetosphere radiates a larger Poynting flux than the linear increase outside of the light cylinder radius. The formed poloidal-current circuit has width, which grows with the electric conductivity. This result contributes to a more concrete dissipative pulsar magnetosphere model.

  6. Effect of Sheet Resistance and Morphology of ITO Thin Films on Polymer Solar Cell Characteristics

    Directory of Open Access Journals (Sweden)

    Ram Narayan Chauhan

    2012-01-01

    Full Text Available Solar cell fabrication on flexible thin plastic sheets needs deposition of transparent conducting anode layers at low temperatures. ITO thin films are deposited on glass by RF sputtering at substrate temperature of 70∘C and compare their phase, morphology, optical, and electrical properties with commercial ITO. The films contain smaller nanocrystallites in (222 preferred orientation and exhibit comparable optical transmittance (~95% in the wavelength range of 550–650 nm, but high sheet resistance of ~103 Ω/□ (the value being ~36 Ω/□ for commercial ITO.The polymer solar cells with PEDOT: PSS and P3HT: PCBM layers realized on RF sputtered vis-a-vis commercial ITO thin films are shown to display a marginal difference in power conversion efficiency, low fill factor, and low open-circuit voltage but increased short-circuit current density. The decrease in fill factor, open-circuit voltage is compensated by increased short-circuit current. Detailed study is made of increased short-circuit current density.

  7. The pitcher plant Sarracenia purpurea can directly acquire organic nitrogen and short-circuit the inorganic nitrogen cycle.

    Directory of Open Access Journals (Sweden)

    Jim D Karagatzides

    2009-07-01

    Full Text Available Despite the large stocks of organic nitrogen in soil, nitrogen availability limits plant growth in many terrestrial ecosystems because most plants take up only inorganic nitrogen, not organic nitrogen. Although some vascular plants can assimilate organic nitrogen directly, only recently has organic nitrogen been found to contribute significantly to the nutrient budget of any plant. Carnivorous plants grow in extremely nutrient-poor environments and carnivory has evolved in these plants as an alternative pathway for obtaining nutrients. We tested if the carnivorous pitcher plant Sarracenia purpurea could directly take up intact amino acids in the field and compared uptake of organic and inorganic forms of nitrogen across a gradient of nitrogen deposition. We hypothesized that the contribution of organic nitrogen to the nitrogen budget of the pitcher plant would decline with increasing nitrogen deposition.At sites in Canada (low nitrogen deposition and the United States (high nitrogen deposition, individual pitchers were fed two amino acids, glycine and phenylalanine, and inorganic nitrogen (as ammonium nitrate, individually and in mixture. Plants took up intact amino acids. Acquisition of each form of nitrogen provided in isolation exceeded uptake of the same form in mixture. At the high deposition site, uptake of organic nitrogen was higher than uptake of inorganic nitrogen. At the low deposition site, uptake of all three forms of nitrogen was similar. Completeness of the associated detritus-based food web that inhabits pitcher-plant leaves and breaks down captured prey had no effect on nitrogen uptake.By taking up intact amino acids, Sarracenia purpurea can short-circuit the inorganic nitrogen cycle, thus minimizing potential bottlenecks in nitrogen availability that result from the plant's reliance for nitrogen mineralization on a seasonally reconstructed food web operating on infrequent and irregular prey capture.

  8. Internal short circuit and accelerated rate calorimetry tests of lithium-ion cells: Considerations for methane-air intrinsic safety and explosion proof/flameproof protection methods.

    Science.gov (United States)

    Dubaniewicz, Thomas H; DuCarme, Joseph P

    2016-09-01

    Researchers with the National Institute for Occupational Safety and Health (NIOSH) studied the potential for lithium-ion cell thermal runaway from an internal short circuit in equipment for use in underground coal mines. In this third phase of the study, researchers compared plastic wedge crush-induced internal short circuit tests of selected lithium-ion cells within methane (CH 4 )-air mixtures with accelerated rate calorimetry tests of similar cells. Plastic wedge crush test results with metal oxide lithium-ion cells extracted from intrinsically safe evaluated equipment were mixed, with one cell model igniting the chamber atmosphere while another cell model did not. The two cells models exhibited different internal short circuit behaviors. A lithium iron phosphate (LiFePO 4 ) cell model was tolerant to crush-induced internal short circuits within CH 4 -air, tested under manufacturer recommended charging conditions. Accelerating rate calorimetry tests with similar cells within a nitrogen purged 353-mL chamber produced ignitions that exceeded explosion proof and flameproof enclosure minimum internal pressure design criteria. Ignition pressures within a 20-L chamber with 6.5% CH 4 -air were relatively low, with much larger head space volume and less adiabatic test conditions. The literature indicates that sizeable lithium thionyl chloride (LiSOCl 2 ) primary (non rechargeable) cell ignitions can be especially violent and toxic. Because ignition of an explosive atmosphere is expected within explosion proof or flameproof enclosures, there is a need to consider the potential for an internal explosive atmosphere ignition in combination with a lithium or lithium-ion battery thermal runaway process, and the resulting effects on the enclosure.

  9. Asutan Motor Searah dengan Tahanan Bertingkat (Direct Current Starting Motor With Grading Resistance)

    OpenAIRE

    Hasto, Agung Tri

    2003-01-01

    The electrical system must has as low aspossible resistance to get high efjisien. One .of that is starting system. In this system, lowest resistance reach when it only use armature resistance. But lower resistance make higher current. In other hand, highest current should not higher than insulation system could take. So this study trying tofind to get safety on the starting system.

  10. MPPT Technique Based on Current and Temperature Measurements

    OpenAIRE

    Vicente, Eduardo Moreira; Moreno, Robson Luiz; Ribeiro, Enio Roberto

    2015-01-01

    This paper presents a new maximum power point tracking (MPPT) method based on the measurement of temperature and short-circuit current, in a simple and efficient approach. These measurements, which can precisely define the maximum power point (MPP), have not been used together in other existing techniques. The temperature is measured with a low cost sensor and the solar irradiance is estimated through the relationship of the measured short-circuit current and its reference. Fast tracking spee...

  11. Current and novel antibiotics against resistant Gram-positive bacteria

    OpenAIRE

    Perez, Federico; Salata, Robert A; Bonomo, Robert A

    2008-01-01

    The challenge posed by resistance among Gram-positive bacteria, epitomized by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and vancomycin-intermediate and -resistant S. aureus (VISA and VRSA) is being met by a new generation of antimicrobials. This review focuses on the new β-lactams with activity against MRSA (ceftobiprole and ceftaroline) and on the new glycopeptides (oritavancin, dalbavancin, and telavancin). It will also consider the role of ...

  12. Sub-module Short Circuit Fault Diagnosis in Modular Multilevel Converter Based on Wavelet Transform and Adaptive Neuro Fuzzy Inference System

    DEFF Research Database (Denmark)

    Liu, Hui; Loh, Poh Chiang; Blaabjerg, Frede

    2015-01-01

    by employing wavelet transform under different fault conditions. Then the fuzzy logic rules are automatically trained based on the fuzzified fault features to diagnose the different faults. Neither additional sensor nor the capacitor voltages are needed in the proposed method. The high accuracy, good...... for continuous operation and post-fault maintenance. In this article, a fault diagnosis technique is proposed for the short circuit fault in a modular multi-level converter sub-module using the wavelet transform and adaptive neuro fuzzy inference system. The fault features are extracted from output phase voltage...

  13. Methicillin-resistant Staphylococcus aureus among animals: current overview.

    Science.gov (United States)

    Aires-de-Sousa, M

    2017-06-01

    Currently, methicillin-resistant Staphylococcus aureus (MRSA) is a universal threat. After being well established in the healthcare setting, it has emerged in the community among people with no risk factors for MRSA acquisition, therefore imposing a new threat. The subsequent detection of MRSA colonizing or infecting animals as well as in food of animal origin was of major concern, revealing new reservoirs for MRSA. The major MRSA clonal lineages circulating in the different settings, i.e. in hospitals, in the community and among animals, are described here, differentiating between clones colonizing companion and food-chain animals. Particular attention is given to the widely spread livestock-associated MRSA clonal complex (CC) 398, which is mainly associated with professional exposure but may be of high pathogenicity. The recent detection of a mecA homologue, designated mecC, with a wide geographical distribution in Europe, and including a large diversity of hosts (food-chain, companion and wildlife animals and also detected in water samples) adds to the threat. Domestication as well as globalization of the livestock industry have intensified exchanges between human and animal bacteria. We report here several cases of transmission of MRSA between companion or food-chain animals and humans, as well as some MRSA clones of human origin that have adapted to new animal hosts eventually by losing useless virulence factors or acquiring new mobile genetic elements. Copyright © 2016 European Society of Clinical Microbiology and Infectious Diseases. Published by Elsevier Ltd. All rights reserved.

  14. Current and novel antibiotics against resistant Gram-positive bacteria

    OpenAIRE

    Perez, Federico

    2008-01-01

    Federico Perez1, Robert A Salata1, Robert A Bonomo21Division of Infectious Diseases and HIV Medicine, University Hospitals Case Medical Center, Cleveland OH, USA; 2Research Service, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, OH, USAAbstract: The challenge posed by resistance among Gram-positive bacteria, epitomized by methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant Enterococcus (VRE) and vancomycin-intermediate and -resis...

  15. Effect of operating current dependent series resistance on the fill factor of a solar cell

    Energy Technology Data Exchange (ETDEWEB)

    Dadu, Meena; Kapoor, A.; Tripathi, K.N. [Department of Electronic Science, University of Delhi, South Campus, Benito Juarez road, -110 021 New Delhi (India)

    2002-02-01

    The fill factor of a solar cell depends upon the series resistance, reverse saturation current, diode quality factor, operating current and voltage. Since the series resistance itself depends upon the operating current (or voltage), it makes the evaluation of fill factor very complicated. In this paper, we have evaluated the fill factor of a solar cell, taking into account operating current dependence of the series resistance.

  16. Evolution of short circuit levels in the National Electric System, years 2007 to 2011; Evolucion de los niveles de cortocircuito del Sistema Electrico Nacional, anos 2007 al 2011

    Energy Technology Data Exchange (ETDEWEB)

    Quintana Castaneda, J; Reyes Escobedo, G [Instituto de Investigaciones Electricas (Mexico)]. E-mails: jqc@iie.org.mx; gustavo.reyes@iie.org.mx; Ibarra Romo, F.G. [Comision Federal de Electricidad (Mexico)]. E-mail: federico.ibarra@cfe.gob.mx

    2013-03-15

    The present document shows an analysis of 2011 short-circuit levels on the different nodes (substations) that integrate the National Electric System. This analysis presents the figures of short-circuit levels on past years, stating on 2007, with the purpose of detecting the variation on each one of these nodes and identify the cases that because it's high levels are considered as critical nodes of the transmission system. At the end of the analysis some recommendations to minimize the potential risks are given on those substations classified as critical nodes. [Spanish] En este documento se expone un analisis de los niveles de cortocircuito que se presentaron en el 2011 en los distintos nodos (subestaciones) que conforman la red del Sistema Electrico Nacional (SEN). Este analisis muestra las cifras de los niveles de cortocircuito que se han presentado desde el ano 2007, a fin de estudiar el comportamiento y evolucion que han tenido los nodos de la red electrica, identificando aquellos puntos que por sus altos niveles de cortocircuito se consideran como nodos criticos. En la parte final del analisis se dan algunas recomendaciones para disminuir los riesgos que se pudieran presentar en aquellas subestaciones clasificadas como nodos criticos.

  17. Finite element model approach of a cylindrical lithium ion battery cell with a focus on minimization of the computational effort and short circuit prediction

    Science.gov (United States)

    Raffler, Marco; Sevarin, Alessio; Ellersdorfer, Christian; Heindl, Simon F.; Breitfuss, Christoph; Sinz, Wolfgang

    2017-08-01

    In this research, a parameterized beam-element-based mechanical modeling approach for cylindrical lithium ion batteries is developed. With the goal to use the cell model in entire vehicle crash simulations, focus of development is on minimizing the computational effort whilst simultaneously obtaining accurate mechanical behavior. The cylindrical cell shape is approximated by radial beams connected to each other in circumferential and longitudinal directions. The discrete beam formulation is used to define an anisotropic material behavior. An 18650 lithium ion cell model constructed in LS-Dyna is used to show the high degree of parameterization of the approach. A criterion which considers the positive pole deformation and the radial deformation of the cell is developed for short circuit prediction during simulation. An abuse testing program, consisting of radial crush, axial crush, and penetration is performed to evaluate the mechanical properties and internal short circuit behavior of a commercially available 18650 lithium cell. Additional 3-point-bending tests are performed to verify the approach objectively. By reducing the number of strength-related elements to 1600, a fast and accurate cell model can be created. Compared to typical cell models in technical literature, simulation time of a single cell load case can be reduced by approx. 90%.

  18. Feasibility Study of the PS Injection for 2 GeV LIU Beams with an Upgraded KFA-45 Injection Kicker System Operating in Short Circuit Mode

    CERN Document Server

    Kramer, Thomas; Borburgh, Jan; Ducimetière, Laurent; Feliciano, Luis; Ferrero Colomo, Alvaro; Goddard, Brennan; Sermeus, Luc

    2016-01-01

    Under the scope of the LIU project the CERN PS Booster to PS beam transfer will be modified to match the requirements for the future 2 GeV beams. This paper describes the evaluation of the proposed upgrade of the PS injection kicker. Different schemes of an injection for LIU beams into the PS have been outlined in the past already under the aspect of individual transfer kicker rise and fall time performances. Homogeneous rise and fall time requirements in the whole PSB to PS transfer chain have been established which allowed to consider an upgrade option of the present injection kicker system operated in short circuit mode. The challenging pulse quality constraints require an improvement of the flat top and post pulse ripples. Both operation modes, terminated and short circuit mode are analysed and analogue circuit simulations for the present and upgraded system are outlined. Recent measurements on the installed kickers are presented and analysed together with the simulation data. First measurements verifying...

  19. Detecting the single line to ground short circuit fault in the submarine’s power system using the artificial neural network

    Directory of Open Access Journals (Sweden)

    Behniafar Ali

    2013-01-01

    Full Text Available The electric marine instruments are newly inserted in the trade and industry, for which the existence of an equipped and reliable power system is necessitated. One of the features of such a power system is that it cannot have an earth system causing the protection relays not to be able to detect the single line to ground short circuit fault. While on the other hand, the occurrence of another similar fault at the same time can lead to the double line fault and thereby the tripping of relays and shortening of vital loads. This in turn endangers the personals' security and causes the loss of military plans. From the above considerations, it is inferred that detecting the single line to ground fault in the marine instruments is of a special importance. In this way, this paper intends to detect the single line to ground fault in the power systems of the marine instruments using the wavelet transform and Multi-Layer Perceptron (MLP neural network. In the numerical analysis, several different types of short circuit faults are simulated on several marine power systems and the proposed approach is applied to detect the single line to ground fault. The results are of a high quality and preciseness and perfectly demonstrate the effectiveness of the proposed approach.

  20. Measurement of direct currents of under 10-10 ampere and of resistances of 1012 Ω for a direct current

    International Nuclear Information System (INIS)

    Vagner, J.

    1965-01-01

    Measurement of weak direct currents by Townsend's method using a vibrating condenser electrometer. Development of a current generator giving a pico-ampere independently of the resistance of the circuit used. Development of generators giving currents which may be adjusted continuously and exactly (0.1 to 1 pico-ampere, 1 to 10 pico-amperes, 10 to 100 pico-amperes). Measurement of very high resistances (10 12 Ω) by three different methods. Graphs are made by plotting the value of the resistance against the potential difference applied across it (from 50 milli-volts to 50 volts). Two methods use adjustable current generators and the third is applicable to the measurement of resistances of between 10 7 and 10 13 Ω using a series of condensers ranging from 50 pico-farads to 10 micro-farads. The accuracy of the measurements is between 0. 5 and 1 per cent. (author) [fr

  1. CURRENT ISSUES REGARDING ENDOCRINE DISRUPTING CHEMICALS AND ANTIBIOTIC RESISTANCE

    Science.gov (United States)

    Recently public concern has increased regarding industrial and environmental substances that may have adverse hormonal effects in human and wildlife populations. This concern has also been expanded to include antibiotic-resistant bacteria and the presence of various antibiotics a...

  2. Resistive mode in rotating plasma columns including the hall current

    International Nuclear Information System (INIS)

    Galvao, R.M.O.

    1983-01-01

    A new resistive mode is shown to exist in rotating plasma columns. The mode is localized in the neighbourhood of the radius where the angular velocity of the bulk plasma is equal to minus half the local angular velocity of the ions. This singular point is caused by the Hall term in the generalized Ohm law. The growth rate of the mode scales with eta sup(1/2), where eta is the plasma resistivity. (Author) [pt

  3. Abnormal contact resistance reduction of bonded copper interconnects in three-dimensional integration during current stressing

    Science.gov (United States)

    Chen, K. N.; Tan, C. S.; Fan, A.; Reif, R.

    2005-01-01

    Bonded copper interconnects were stressed with current to measure the specific contact resistance. For bonded copper interconnects without a prebonding HCl clean, the corresponding specific contact resistance did not change while increasing the stress current. However, for some interconnects with the prebonding HCl clean, an abnormal contact resistance reduction was observed during the increase of the stress current. The rise of temperature at the bonding interface area due to Joule heating under high current density may have caused the decrease of contact resistance. This behavior may be one option for quality enhancement in 3D integration at low temperature.

  4. Current perspectivesin pathogenesis and antimicrobial resistance of enteroaggregative Escherichia coli.

    Science.gov (United States)

    Kong, Haishen; Hong, Xiaoping; Li, Xuefen

    2015-08-01

    Enteroaggregative Escherichia coli (EAEC) is an emerging pathogen that causes acute and persistent diarrhea in children and adults. While the pathogenic mechanisms of EAEC intestinal colonization have been uncovered (including bacterial adhesion, enterotoxin and cytotoxin secretion, and stimulation of mucosal inflammation), those of severe extraintestinal infections remain largely unknown. The recent emergence of multidrug resistant EAEC represents an alarming public health threat and clinical challenge, and research on the molecular mechanisms of resistance is urgently needed. Copyright © 2015 Elsevier Ltd. All rights reserved.

  5. Current concepts in the management of resistant hypertension: a ...

    African Journals Online (AJOL)

    Background: Resistant hypertension is defined as uncontrolled hypertension above the target goal despite treatment with 3 or more antihypertensive agents, one of which is a diuretic, at optimum and best tolerated doses. The target blood pressure is defined as < 140/90 mmHg in most people and < 130/80 mmHg in those ...

  6. Size optimization for complex permeability measurement of magnetic thin films using a short-circuited microstrip line up to 30 GHz

    Science.gov (United States)

    Takeda, Shigeru; Naoe, Masayuki

    2018-03-01

    High-frequency permeability spectra of magnetic films were measured over a wideband frequency range of 0.1-30 GHz using a shielded and short-circuited microstrip line jig. In this measurement, spurious resonances had to be suppressed up to the highest frequency. To suppress these resonances, characteristic impedance of the microstrip line should approach 50 Ω at the junction between connector and microstrip line. The main factors dominating these resonances were structures of the jig and the sample. The dimensions were optimized in various experiments, and results demonstrated that the frequency could be raised to at least 20 GHz. For the transverse electromagnetic mode to transmit stably along the microstrip line, the preferred sample was rectangular, with the shorter side parallel to the line and the longer side perpendicular to it, and characteristic impedance strongly depended on the signal line width of the jig. However, too small a jig and sample led to a lower S/N ratio.

  7. Design of power balance SRAM for DPA-resistance

    Science.gov (United States)

    Keji, Zhou; Pengjun, Wang; Liang, Wen

    2016-04-01

    A power balance static random-access memory (SRAM) for resistance to differential power analysis (DPA) is proposed. In the proposed design, the switch power consumption and short-circuit power consumption are balanced by discharging and pre-charging the key nodes of the output circuit and adding an additional short-circuit current path. Thus, the power consumption is constant in every read cycle. As a result, the DPA-resistant ability of the SRAM is improved. In 65 nm CMOS technology, the power balance SRAM is fully custom designed with a layout area of 5863.6 μm2. The post-simulation results show that the normalized energy deviation (NED) and normalized standard deviation (NSD) are 0.099% and 0.04%, respectively. Compared to existing power balance circuits, the power balance ability of the proposed SRAM has improved 53%. Project supported by the Zhejiang Provincial Natural Science Foundation of China (No. LQ14F040001), the National Natural Science Foundation of China (Nos. 61274132, 61234002), and the K. C. Wong Magna Fund in Ningbo University, China.

  8. Controlled short-circuiting MIG-MAG welding process and procedures applied to the root pass in pipeline construction; Processo de soldagem MIG/MAG em curto-circuito controlado e procedimentos aplicados ao passe de raiz na construcao de linhas dutoviarias

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Regis H.G. e; Gohr Junior, Raul; Weck, Leonardo W.A. [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica. Lab. de Soldagem e Mecatronica (LABSOLDA)

    2005-07-01

    The work deals with the study and development of the Controlled Short-Circuiting MIG/MAG Welding Process (CCC) and procedures for the root pass on pipes, in pipelines construction. The developed process (CCC) consists in an semi-automatic slag free operation, yielding higher productivity than the Coated Electrode and TIG processes, with satisfactory properties on the root weld. The significant influence of the welding over the time schedule and construction cost makes the development of this technology attractive, in order to become available at low cost, enhancing the companies' competitiveness in the globalized oil sector. The developed system, a MIG/MAG variant, features the advantages of short-circuiting metal transfer and avoids its inconveniences (mainly with high CO{sub 2} content gases), enabling its use on pipes root welding. This is possible through current waveform control, providing process and weld pool stability. Procedures for the root pass were determined for each of the welding positions reached in thick walled pipes welding, with the CCC. Also, the low welder training time was notable. (author)

  9. Management of patients with resistant hypertension: current treatment options

    Directory of Open Access Journals (Sweden)

    Kumar N

    2013-10-01

    Full Text Available Nilay Kumar,1 David A Calhoun,2 Tanja Dudenbostel21Department of Medicine, 2Division of Cardiovascular Disease, Hypertension and Vascular Biology Program, University of Alabama at Birmingham, Birmingham, AL, USAAbstract: Resistant hypertension (RHTN is an increasingly common clinical problem that is often heterogeneous in etiology, risk factors, and comorbidities. It is defined as uncontrolled blood pressure on optimal doses of three antihypertensive agents, ideally one being a diuretic. The definition also includes controlled hypertension with use of four or more antihypertensive agents. Recent observational studies have advanced the characterization of patients with RHTN. Patients with RHTN have higher rates of cardiovascular events and mortality compared with patients with more easily controlled hypertension. Secondary causes of hypertension, including obstructive sleep apnea, primary aldosteronism, renovascular disease, are common in patients with RHTN and often coexist in the same patient. In addition, RHTN is often complicated by metabolic abnormalities. Patients with RHTN require a thorough evaluation to confirm the diagnosis and optimize treatment, which typically includes a combination of lifestyle adjustments, and pharmacologic and interventional treatment. Combination therapy including a diuretic, a long-acting calcium channel blocker, an angiotensin-converting enzyme inhibitor, a beta blocker, and a mineralocorticoid receptor antagonist where warranted is the classic regimen for patients with treatment-resistant hypertension. Mineralocorticoid receptor antagonists like spironolactone or eplerenone have been shown to be efficacious in patients with RHTN, heart failure, chronic kidney disease, and primary aldosteronism. Novel interventional therapies, including baroreflex activation and renal denervation, have shown that both of these methods may be used to lower blood pressure safely, thereby providing exciting and promising new

  10. Ground Return Current Behaviour in High Voltage Alternating Current Insulated Cables

    Directory of Open Access Journals (Sweden)

    Roberto Benato

    2014-12-01

    Full Text Available The knowledge of ground return current in fault occurrence plays a key role in the dimensioning of the earthing grid of substations and of cable sealing end compounds, in the computation of rise of earth potential at substation sites and in electromagnetic interference (EMI on neighbouring parallel metallic conductors (pipes, handrails, etc.. Moreover, the ground return current evaluation is also important in steady-state regime since this stray current can be responsible for EMI and also for alternating current (AC corrosion. In fault situations and under some assumptions, the ground return current value at a substation site can be computed by means of k-factors. The paper shows that these simplified and approximated approaches have a lot of limitations and only multiconductor analysis can show the ground return current behaviour along the cable (not only the two end values both in steady-state regime and in short circuit occurrence (e.g., phase-to-ground and phase-to-phase-to-ground. Multiconductor cell analysis (MCA considers the cable system in its real asymmetry without simplified and approximated hypotheses. The sensitivity of ground return current on circuit parameters (cross-bonding box resistances, substation earthing resistances, soil resistivity is presented in the paper.

  11. The Current State of Macrolide Resistance in Campylobacter spp.: Trends and Impacts of Resistance Mechanisms.

    Science.gov (United States)

    Bolinger, Hannah; Kathariou, Sophia

    2017-06-15

    Campylobacter spp., especially Campylobacter jejuni and C. coli , are leading bacterial foodborne pathogens worldwide. In the United States, an estimated 0.8 million cases of campylobacteriosis occur annually, mostly involving C. jejuni Campylobacteriosis is generally self-limiting, but in severe cases, treatment with antibiotics may be mandated. The increasing incidence of fluoroquinolone resistance in Campylobacter has rendered macrolides such as erythromycin and azithromycin the drugs of choice for human campylobacteriosis. The prevalence of macrolide resistance in C. jejuni remains low, but macrolide resistance can be common in C. coli Substitutions in the 23S rRNA gene, specifically A2075G, and less frequently A2074C/G, remain the most common mechanism for high-level resistance to macrolides. In C. jejuni , resistance mediated by such substitutions is accompanied by a reduced ability to colonize chickens and other fitness costs, potentially contributing to the low incidence of macrolide resistance. Interestingly, similar fitness impacts have not been noted in C. coli Also noteworthy is a novel mechanism first reported in 2014 for a C. coli isolate from China and mediated by erm (B) harbored on multidrug resistance genomic islands. The incidence of erm (B) appears to reflect clonal expansion of certain strains, and whole-genome sequencing has been critical to the elucidation of erm (B)-associated macrolide resistance in Campylobacter spp. With the exception of one report from Spain, erm (B)-mediated macrolide resistance has been restricted to Campylobacter spp., mostly C. coli , of animal and human origin from China. If erm (B)-mediated macrolide resistance does not confer fitness costs in C. jejuni , the range of this gene may expand in C. jejuni , threatening to compromise treatment effectiveness for severe campylobacteriosis cases. Copyright © 2017 American Society for Microbiology.

  12. Stochastic macromodel of magnetic tunnel junction resistance variation and critical current dependence on resistance variation for SPICE simulation

    Science.gov (United States)

    Choi, Juntae; Song, Yunheub

    2017-04-01

    The resistance distribution of a magnetic tunnel junction (MTJ) shows nonuniformity according to various MTJ parameters. Moreover, this resistance variation leads to write-current density variation, which can cause serious problems when designing peripheral circuits for spin transfer torque magnetoresistance random access memory (STT-MRAM) and commercializing gigabit STT-MRAM. Therefore, a macromodel of MTJ including resistance, tunneling magnetoresistance ratio (TMR), and critical current variations is required for circuit designers to design MRAM peripheral circuits, that can overcome the various effects of the variations, such as write failure and read failure, and realize STT-MRAM. In this study, we investigated a stochastic behavior macromodel of the write current dependence on the MTJ resistance variation. The proposed model can possibly be used to analyze the write current density in relation to the resistance and TMR variations of MTJ with various parameter variations. It can be very helpful for designing STT-MRAM circuits and simulating the operation of STT-MRAM devices considering MTJ variations.

  13. Investigation on the Short-Circuit Behavior of an Aged IGBT Module Through a 6 kA/1.1 kV Non-Destructive Testing Equipment

    DEFF Research Database (Denmark)

    Wu, Rui; Smirnova, Liudmila; Iannuzzo, Francesco

    2014-01-01

    This paper describes the design and development of a 6 kA/1.1 kV non-destructive testing system, which aims for short circuit testing of high-power IGBT modules. An ultralow stray inductance of 37 nH is achieved in the implementation of the tester. An 100 MHz FPGA supervising unit enables 10 ns l...

  14. Open- and Short-Circuit Fault Identification for a Boost dc/dc Converter in PV MPPT Systems

    Directory of Open Access Journals (Sweden)

    Diego R. Espinoza Trejo

    2018-03-01

    Full Text Available This paper proposes a fault identification system for short and open-circuit switch faults (SOCSF for a dc/dc converter acting as a Maximum Power Point Tracker (MPPT in Photovoltaic (PV systems. A closed-loop operation is assumed for the boost dc/dc converter. A linearizing control plus a Proportional-Derivative (PD controller is suggested for PV voltage regulation at the maximum power point (MPP. In this study, the SOCSF are modeled by using an additive fault representation and the fault identification (FI system is synthesized departing from a Luenberger observer. Hence, an FI signal is obtained, which is insensitive to irradiance and load current changes, but affected by the SOCSF. For FI purposes, only the sensors used in the control system are needed. Finally, an experimental evaluation is presented by using a solar array simulator dc power supply and a boost dc/dc converter of 175 W in order to validate the ideas this study exposes.

  15. Modeling of Current Transformers Under Saturation Conditions

    Directory of Open Access Journals (Sweden)

    Martin Prochazka

    2006-01-01

    Full Text Available During a short circuit the input signal of the relay can be distort by the magnetic core saturation of the current transformer. It is useful to verify the behavior of CT by a mathematical model. The paper describes one phase and three phase models and it presents some methods of how to analyze and classify a deformed secondary current

  16. The early effect of dextran sodium sulfate administration on carbachol-induced short-circuit current in distal and proximal colon during colitis development

    Czech Academy of Sciences Publication Activity Database

    Hock, M.; Soták, Matúš; Kment, M.; Pácha, J.

    2011-01-01

    Roč. 60, č. 6 (2011), s. 921-931 ISSN 0862-8408 Grant - others:Univerzita Karlova(CZ) 25410 Institutional research plan: CEZ:AV0Z50110509 Keywords : cholinergic * ion transport * colitis * distal and proximal colon * ussing chamber Subject RIV: FP - Other Medical Disciplines Impact factor: 1.555, year: 2011

  17. A fast fault protection based on direction of bus-side capacitor discharge current for a high-surety power supply

    DEFF Research Database (Denmark)

    Li, Haijin; Chen, Min; Yang, Boping

    2017-01-01

    A short-circuit fault protection strategy based on the direction of bus-side capacitor discharge current for a high-surety power supply, known as Super Uninterruptable Power Supply (Super UPS), is studied in this paper. It consists of multiple energy sources and storage components. All energy...... strategy is necessary to keep the uninterruptable power for the critical load. In this paper, the characteristics of the short-circuit fault are analyzed first. Then, a fast short-circuit fault locating and isolating strategy based on the direction of the discharge current of the busside capacitors...

  18. Adaptation to high current using low external resistances eliminates power overshoot in microbial fuel cells

    KAUST Repository

    Hong, Yiying

    2011-10-01

    One form of power overshoot commonly observed with mixed culture microbial fuel cells (MFCs) is doubling back of the power density curve at higher current densities, but the reasons for this type of overshoot have not been well explored. To investigate this, MFCs were acclimated to different external resistances, producing a range of anode potentials and current densities. Power overshoot was observed for reactors acclimated to higher (500 and 5000. Ω) but not lower (5 and 50. Ω) resistances. Acclimation of the high external resistance reactors for a few cycles to low external resistance (5. Ω), and therefore higher current densities, eliminated power overshoot. MFCs initially acclimated to low external resistances exhibited both higher current in cyclic voltammograms (CVs) and higher levels of redox activity over a broader range of anode potentials (-0.4 to 0. V; vs. a Ag/AgCl electrode) based on first derivative cyclic voltammetry (DCV) plots. Reactors acclimated to higher external resistances produced lower current in CVs, exhibited lower redox activity over a narrower anode potential range (-0.4 to -0.2. V vs. Ag/AgCl), and failed to produce higher currents above ∼-0.3. V (vs. Ag/AgCl). After the higher resistance reactors were acclimated to the lowest resistance they also exhibited similar CV and DCV profiles. Our findings show that to avoid overshoot, prior to the polarization and power density tests the anode biofilm must adapt to low external resistances to be capable of higher currents. © 2011 Elsevier B.V.

  19. Insulin resistance modifies the association between obesity and current asthma in adults.

    Science.gov (United States)

    Cardet, Juan Carlos; Ash, Samuel; Kusa, Tope; Camargo, Carlos A; Israel, Elliot

    2016-08-01

    Insulin resistance potentiates the association between obesity and childhood asthma, but this relationship appears inconsistent in relatively small studies of adults. We investigated effect modification in adults using the National Health and Nutrition Examination Survey 2003-2012, a large, nationally representative database.Insulin resistance and a history of physician-diagnosed current asthma were obtained from 12 421 adults, ages 18-85 years. We used logistic regression to determine associations between obesity and current asthma, adjusting for age, sex, race/ethnicity, poverty income ratio and smoking status. An interaction term evaluated effect modification by insulin resistance of the obesity-asthma association.As expected, obesity was positively associated with current asthma. Insulin resistance modified this association, with obesity measured as body mass index, waist circumference or waist-to-height ratio. The relationship between obesity and current asthma was stronger with increasing insulin resistance tertiles (OR 2.05, 95% CI 2.76-3.00; p-value for interaction 0.03). This association was robust to adjustments for other components of the metabolic syndrome (hypertriglyceridaemia, hypertension, hyperglycaemia and systemic inflammation). None of these components were themselves effect modifiers of the obesity-asthma association.In this large, nationally representative sample, insulin resistance modified the association between obesity and current asthma in adults. Targeting insulin resistance may represent a novel therapeutic strategy for obese patients with asthma. Copyright ©ERS 2016.

  20. Use of Direct Current Resistivity Measurements to Assess AISI 304 Austenitic Stainless Steel Sensitization

    OpenAIRE

    Mesquita, Ramaiany Carneiro; Mecury, José Manoel Rivas; Tanaka, Auro Atsumi; Sousa, Regina Célia de

    2015-01-01

    This paper describes the feasibility of using direct current electrical resistivity measurements to evaluate AISI 304 austenitic stainless steel sensitization. ASTM A262 – Practice A and double loop electrochemical potentiodynamic reactivation (DL-EPR) tests were performed to assess the degree of sensitization (DoS) qualitatively and quantitatively, and electrical resistivity (ER) was measured by the four-point direct-current potential drop method. The results indicate that the DoS incr...

  1. Asbestos as 'toxic short-circuit' optic-fibre for UV within the cell-net: — Likely roles and hazards for secret UV and IR metabolism

    International Nuclear Information System (INIS)

    Traill, Robert R

    2011-01-01

    The most toxic asbestos fibres have widths 250nm-10nm, and this toxicity is 'physical', which could mean either mechanical or optical: Tangling with chromosomes is a mechanical hazard occasionally reported, and fibres 100nm wide — or chrysotile (white asbestos) is >150nm. In both cases, UV A /UV B -transmission would then predominate. (Chrysotile 150nm might be benign — escaping both mechanical and optical!). But what would generate such UV, and why would its transmission be toxic? Thar and Kühl (J.Theor.Biol.:2004) explain that the long mitochondria on microtubules may be able to act as UV-lasers, (and many observers since Gurwitsch 1923 have reported ultraweak UV emissions escaping from all types of living bio-tissue). That all suggests some universal secret role for UV, apparently related to mitosis. Insertion of fibre 'short-circuits' could then cause upsets in mitosis-control, and hence DNA irregularities. Such UV-control could parallel similar lower-powered Infra-Red control-systems (as considered elsewhere for coaxial myelin; or as portrayed by G.Albrecht-Buehler's online animations etc.); and the traditional short mitochondria seem better suited for this IR task.

  2. Fault Reactivation Can Generate Hydraulic Short Circuits in Underground Coal Gasification—New Insights from Regional-Scale Thermo-Mechanical 3D Modeling

    Directory of Open Access Journals (Sweden)

    Christopher Otto

    2016-09-01

    Full Text Available Underground coal gasification (UCG has the potential to increase worldwide coal reserves by utilization of coal deposits not mineable by conventional methods. This involves combusting coal in situ to produce a synthesis gas, applicable for electricity generation and chemical feedstock production. Three-dimensional (3D thermo-mechanical models already significantly contribute to UCG design by process optimization and mitigation of the environmental footprint. We developed the first 3D UCG model based on real structural geological data to investigate the impacts of using isothermal and non-isothermal simulations, two different pillar widths and four varying regional stress regimes on the spatial changes in temperature and permeability, ground surface subsidence and fault reactivation. Our simulation results demonstrate that non-isothermal processes have to be considered in these assessments due to thermally-induced stresses. Furthermore, we demonstrate that permeability increase is limited to the close reactor vicinity, although the presence of previously undetected faults can introduce formation of hydraulic short circuits between single UCG channels over large distances. This requires particular consideration of potentially present sub-seismic faults in the exploration and site selection stages, since the required pillar widths may be easily underestimated in presence of faults with different orientations with respect to the regional stress regime.

  3. Characterization of the voltage control systems and speed of a synchronous machine of high power for short circuit testing; Caracterizacion de los sistemas de control de voltaje y velocidad de una maquina sincrona de alta potencia para pruebas de corto circuito

    Energy Technology Data Exchange (ETDEWEB)

    Segura Ozuna, Victor Octavio; Hernandez Rodriguez, Isaura Victoria; Alcaide Godinez, Indira Xochiquetzal; Garduno Ramirez, Raul; Montero Cervantes, Julio Cesar [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Ruiz Rodriguez, Genaro; Martinez Torres; Ricardo [CFE-LAPEM, Irapuato, Guanajuato (Mexico)

    2012-07-01

    This paper introduces a characterization of the behavior of the speed and voltage control systems of a special purpose synchronous machine (GCC) based on measuring and monitoring physical signals, and recording of the sampled waveforms. Basically, the GCC supplies the energy to perform high-power short-circuits tests to certify electrical equipment and components, as required by the Comision Federal de Electricidad (CFE) in Mexico. The GCC operates alternately as motor and generator. With the GCC operating as motor, speed control during startup, acceleration, re-acceleration and braking is carried out by a static frequency converter (SFC). Complementary, the voltage controller manipulates excitation power to control terminal voltage when the GCC operates as generator and regulates excitation current when the GCC operates as motor. Compared to conventional voltage regulation systems, which must go off in case of short-circuit, the GCC voltage regulator must keep controlling field excitation to maintain the required line current and terminal voltage during short-circuit tests. Monitoring of physical signals was carried out with a portable data acquisition system based on SCXI and PXI digital platforms. A total of 78 signals were monitored with a 6 kHz sampling rate that was enough to obtain detailed signal waveforms. Data captured was processed and plotted for analysis. The signal graphs show the current real behavior of both, the voltage control system and the speed control system, and constitute a precise characterization of their behavior. [Spanish] Este documento presenta una caracterizacion del comportamiento de los sistemas de control de velocidad y voltaje de una maquina sincrona de proposito especial (GCC) basada en la medicion y monitoreo de senales fisicas, asi como en el registro de las formas de onda muestreadas. Basicamente, la GCC suministra la energia para efectuar pruebas de corto circuito de alta potencia para certificar equipo y componentes

  4. Antimicrobial resistance among Enterobacteriaceae in South America: history, current dissemination status and associated socioeconomic factors.

    Science.gov (United States)

    Bonelli, Raquel Regina; Moreira, Beatriz Meurer; Picão, Renata Cristina

    2014-04-01

    South America exhibits some of the higher rates of antimicrobial resistance in Enterobactericeae worldwide. This continent includes 12 independent countries with huge socioeconomic differences, where the ample access to antimicrobials, including counterfeit ones, coexists with ineffective health systems and sanitation problems, favoring the emergence and dissemination of resistant strains. This work presents a literature review concerning the evolution and current status of antimicrobial resistance threats found among Enterobacteriaceae in South America. Resistance to β-lactams, fluoroquinolones and aminoglycosides was emphasized along with description of key epidemiological studies that highlight the success of specific resistance determinants in different parts of the continent. In addition, a discussion regarding political and socioeconomic factors possibly related to the dissemination of antimicrobial resistant strains in clinical settings and at the community is presented. Finally, in order to assess the possible sources of resistant bacteria, we compile the current knowledge about the occurrence of antimicrobial resistance in isolates in South American' food, food-producing animals and off-hospitals environments. By addressing that intensive intercontinental commerce and tourism neutralizes the protective effect of geographic barriers, we provide arguments reinforcing that globally integrated efforts are needed to decelerate the emergence and dissemination of antimicrobial resistant strains. Copyright © 2014 Elsevier Ltd. All rights reserved.

  5. A Modified Time-Delay Addition Method to Extract Resistive Leakage Current of MOSA

    Science.gov (United States)

    Khodsuz, Masume; Mirzaie, Mohammad

    2016-12-01

    Metal oxide surge arresters are one of the most important equipment for power system protection against switching and lightning over-voltages. High-energy stresses and environmental features are the main factors which degrade surge arresters. In order to verify surge arresters good condition, their monitoring is necessary. The majority of surge arrester monitoring techniques is based on total leakage current decomposition of their capacitive and resistive components. This paper introduces a new approach based on time-delay addition method to extract the resistive current from the total leakage current without measuring voltage signal. Surge arrester model for calculating leakage current has been performed in ATP-EMTP. In addition, the signal processing has been done using MATLAB software. To show the accuracy of the proposed method, experimental tests have been performed to extract resistive leakage current by the proposed method.

  6. Um critério para determinar a regulagem da tensão em soldagem MIG/MAG por curto-circuito A criterion to determine voltage setting in short-circuit GMAW

    Directory of Open Access Journals (Sweden)

    Gabriel Maradei Carneiro de Rezende

    2011-06-01

    Full Text Available Este trabalho apresenta um estudo exploratório sobre um critério denominado "Critério Laprosolda para Estabilidade de Transferência em MIG/MAG com curto-circuito", o qual tem por finalidade uma análise quantitativa da regularidade da transferência metálica para regulagem de parâmetros para soldagem MIG/MAG por curto circuito convencional. Inicialmente é apresentado o embasamento para elaboração deste critério. A avaliação da confiabilidade do mesmo foi feita por meio de soldagens e comparações dos resultados com o rendimento de deposição e com as características geométricas do cordão de solda. Para isto, chapas de teste com 3,18 mm de espessura e abertura de raiz de 1 mm entre elas foram soldadas, dentro dos mesmos parâmetros de corrente e velocidade de alimentação, usando arame AWS ER70S-6 de 1,2 mm de diâmetro protegido pela mistura Argônio 85% - Dióxido de Carbono 15%. Para atender a relação proposta, varreu-se a regulagem de tensões de soldagem desde valores muito baixos até muito altos para o que se esperava para esta condição de soldagem. Os resultados confirmam a efetividade do "Índice de Regularidade" como meio de avaliar regulagens de soldagem MIG/MAG visando minimizar respingos e otimizar o acabamento do cordão.This paper presents an exploratory study on a criterion called "Criterion for Stability Laprosolda Transfer in MIG / MAG with short circuit", which aims at a quantitative analysis of the regularity of metal transfer for setting parameters for MIG / MAG conventional in short circuit. Initially it is stated the foundation for development of this criterion. The evaluation of that was made by welding and comparisons of results with the efficiency of deposition and the geometric characteristics of the weld bead. For this, the test plates with 3.18 mm thick and 1 mm gap between them was welded in the same range of current and feeding speed, using wire AWS ER70S-6 1.2 mm of diameter protected by the

  7. Resistive flux saving and current profile control during lower hybrid waves assisted current rise in TORE SUPRA

    International Nuclear Information System (INIS)

    van Houtte, D.; Hoang, G.T.; Joffrin, E.; Lecoustey, P.; Moreau, D.; Parlange, F.; Tonon, G.; Vallet, J.C.

    1992-01-01

    Resistive flux saving at densities n e = (1 - 2) x 10 19 m -3 has been studied. High flux saving efficiency (0.7 x 10 13 Wb/J/m -1 ) can be achieved for a low rf power (P LH = 0.5 MW) due to the beneficial effect of the electric field on the suprathermal electrons. However for power higher than 1 MW, the efficiency is 0.25 x 10 13 Wb/J/m -1 . This flux saving efficiency is comparable to the one obtained during the flat top phase. The application of the LH power during a low density current ramp-up tends to peak the electron temperature and current density profiles. The rf power level, the parallel wavenumber and the current ramp rate allow to control the trajectories of the plasma discharges during the current rise inside the MHD stable domain

  8. Simulation of temperature rise in Li-ion cells at very high currents

    Science.gov (United States)

    Mao, Jing; Tiedemann, William; Newman, John

    2014-12-01

    The Dualfoil model is used to simulate the electrochemical behavior and temperature rise for MCMB/LiCoO2 Li-ion cells under a small constant-resistance load, approaching a short-circuit condition. Radial mass transport of lithium from the center of the pore to the pore wall has been added to the model to describe better current limitations at very high discharge currents. Electrolyte and solid-surface-concentration profiles of lithium ions across the cell at various times are developed and analyzed to explain the lithium-ion transport limitations. Sensitivity tests are conducted by changing solution and solid-state diffusion coefficients, and the heat-transfer coefficient. Because diffusion coefficients increase at high temperature, calculated discharge curves can show currents dropping initially but then rising to a second peak, with most of the available capacity being consumed in the second peak. Conditions which lead to such a second peak are explored.

  9. Resistive wall heating due to image current on the beam chamber for a superconducting undulator.

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. H. (Accelerator Systems Division (APS))

    2012-03-27

    The image-current heating on the resistive beam chamber of a superconducting undulator (SCU) was calculated based on the normal and anomalous skin effects. Using the bulk resistivity of copper for the beam chamber, the heat loads were calculated for the residual resistivity ratios (RRRs) of unity at room temperature to 100 K at a cryogenic temperature as the reference. Then, using the resistivity of the specific aluminum alloy 6053-T5, which will be used for the SCU beam chamber, the heat loads were calculated. An electron beam stored in a storage ring induces an image current on the inner conducting wall, mainly within a skin depth, of the beam chamber. The image current, with opposite charge to the electron beam, travels along the chamber wall in the same direction as the electron beam. The average current in the storage ring consists of a number of bunches. When the pattern of the bunched beam is repeated according to the rf frequency, the beam current may be expressed in terms of a Fourier series. The time structure of the image current is assumed to be the same as that of the beam current. For a given resistivity of the chamber inner wall, the application ofthe normal or anomalous skin effect will depend on the harmonic numbers of the Fourier series of the beam current and the temperature of the chamber. For a round beam chamber with a ratius r, much larger than the beam size, one can assume that the image current density as well as the density square, may be uniform around the perimeter 2{pi}r. For the SCU beam chamber, which has a relatively narrow vertical gap compared to the width, the effective perimeter was estimated since the heat load should be proportional to the inverse of the perimeter.

  10. Antimicrobial resistance in Helicobacter pylori: current situation and management strategy in Vietnam.

    Science.gov (United States)

    Phan, Trung Nam; Tran, Van Huy; Tran, Thi Nhu Hoa; Le, Van An; Santona, Antonella; Rubino, Salvatore; Paglietti, Bianca

    2015-07-04

    Increasing antimicrobial resistance to key antibiotics in Helicobacter pylori has become a main cause of treatment failures in many countries, including Vietnam. For this reason it is advisable to perform antimicrobial sensitivity tests to provide more focused regimens for H. pylori eradication. However, this approach is generally unavailable for H. pylori in Vietnam and the selection of treatment regimens is mainly based on the trend of antibiotic use in the population, resistance development in the region, and history of H. pylori eradication of patients. The aim of this review is to examine the current situation of antimicrobial resistance in Vietnam and suggest management strategies for treatment selection.

  11. Investigation of the resistive transition of MgB{sub 2} thin film through current noise

    Energy Technology Data Exchange (ETDEWEB)

    Gandini, C [IEN G. Ferraris, Strada delle Cacce 91, 10135 Turin (Italy); Rajteri, M [IEN G. Ferraris, Strada delle Cacce 91, 10135 Turin (Italy); Portesi, C [IEN G. Ferraris, Strada delle Cacce 91, 10135 Turin (Italy); Monticone, E [IEN G. Ferraris, Strada delle Cacce 91, 10135 Turin (Italy); Masoero, A [Dip. di Scienze e Tecnologie Avanzate, Universita del Piemonte Orientale ' Amedeo Avogadro' , Piazza Ambrosoli 5, 15100 Alessandria (Italy); Mazzetti, P [INFM-Dip. Fisica, Politecnico di Torino, C. Duca degli Abruzzi 24, 10129 Turin (Italy)

    2006-06-01

    In this paper we present measurements concerning the current noise produced during the resistive transition in a MgB{sub 2} polycrystalline thin film. The power spectrum of the current noise, observed when the temperature is slowly changed across its critical value, presents a large electrical noise of the 1/f{sup n} type (n {approx_equal} 3) over a quite wide range of frequencies. This noise may be considered as generated by the abrupt creation of resistive strips across the specimen constituted by grains which have undergone the resistive transition. A computer model that takes into account fluctations of the grain critical currents and of the number of grain per strips, has been developed to simulate the resistive transition and to evaluate the noise power spectrum. When the temperature is incresed and reaches its critical value, resistive strips are formed according to a percolative process, giving rise to resistance steps which are at the origin of the noise. The theoretical results obtained by this model are in good agreement, concerning both the shape and intensity of the noise power spectrum, with the experimental data directly measured on the specimen.

  12. Investigation of the resistive transition of MgB2 thin film through current noise

    International Nuclear Information System (INIS)

    Gandini, C; Rajteri, M; Portesi, C; Monticone, E; Masoero, A; Mazzetti, P

    2006-01-01

    In this paper we present measurements concerning the current noise produced during the resistive transition in a MgB 2 polycrystalline thin film. The power spectrum of the current noise, observed when the temperature is slowly changed across its critical value, presents a large electrical noise of the 1/f n type (n ≅ 3) over a quite wide range of frequencies. This noise may be considered as generated by the abrupt creation of resistive strips across the specimen constituted by grains which have undergone the resistive transition. A computer model that takes into account fluctations of the grain critical currents and of the number of grain per strips, has been developed to simulate the resistive transition and to evaluate the noise power spectrum. When the temperature is incresed and reaches its critical value, resistive strips are formed according to a percolative process, giving rise to resistance steps which are at the origin of the noise. The theoretical results obtained by this model are in good agreement, concerning both the shape and intensity of the noise power spectrum, with the experimental data directly measured on the specimen

  13. Influence of helical external driven current on nonlinear resistive tearing mode evolution and saturation in tokamaks

    Science.gov (United States)

    Zhang, W.; Wang, S.; Ma, Z. W.

    2017-06-01

    The influences of helical driven currents on nonlinear resistive tearing mode evolution and saturation are studied by using a three-dimensional toroidal resistive magnetohydrodynamic code (CLT). We carried out three types of helical driven currents: stationary, time-dependent amplitude, and thickness. It is found that the helical driven current is much more efficient than the Gaussian driven current used in our previous study [S. Wang et al., Phys. Plasmas 23(5), 052503 (2016)]. The stationary helical driven current cannot persistently control tearing mode instabilities. For the time-dependent helical driven current with f c d = 0.01 and δ c d < 0.04 , the island size can be reduced to its saturated level that is about one third of the initial island size. However, if the total driven current increases to about 7% of the total plasma current, tearing mode instabilities will rebound again due to the excitation of the triple tearing mode. For the helical driven current with time dependent strength and thickness, the reduction speed of the radial perturbation component of the magnetic field increases with an increase in the driven current and then saturates at a quite low level. The tearing mode is always controlled even for a large driven current.

  14. Effect of decreasing electrical resistance in Characeae cell membranes caused by the flow of alternating current

    Directory of Open Access Journals (Sweden)

    Edward Śpiewla

    2014-01-01

    Full Text Available By means of the techniques of external electrodes and microelectrodes, it was found that evanescent flow of an alternating current through plasmalemma of Characeae cells neutralises oscillatory change in their electrical resistance and reversibly diminishes its value. This effect is particularly significant in the case of "high resistance cells", but it weakens with increasing temperature. The value of the estimated activation energy indicates that, after flow of the alternating current through the membrane, a rapid increase in the conductivity may be caused by an increase in conductivity of potassium channels. This result seems to support the hypothesis of electroconformational feedback.

  15. Low-energy Resistive Random Access Memory Devices with No Need for a Compliance Current

    OpenAIRE

    Xu, Zedong; Yu, Lina; Wu, Yong; Dong, Chang; Deng, Ning; Xu, Xiaoguang; Miao, J.; Jiang, Yong

    2015-01-01

    A novel resistive random access memory device is designed with SrTiO3/ La2/3Sr1/3MnO3 (LSMO)/MgAl2O4 (MAO)/Cu structure, in which metallic epitaxial LSMO is employed as the bottom electrode rather than traditional metal materials. In this device, the critical external compliance current is no longer necessary due to the high self-resistance of LSMO. The LMSO bottom electrode can act as a series resistor to offer a compliance current during the set process. Besides, the device also has excelle...

  16. Study on Oscillations during Short Circuit of MW-Scale IGBT Power Modules by Means of a 6-kA/1.1-kV Nondestructive Testing System

    DEFF Research Database (Denmark)

    Wu, Rui; Diaz Reigosa, Paula; Iannuzzo, Francesco

    2015-01-01

    This paper uses a 6-kA/1.1-kV nondestructive testing system for the analysis of the short-circuit behavior of insulated-gate bipolar transistor (IGBT) power modules. A field-programmable gate array enables the definition of control signals to an accuracy of 10 ns. Multiple 1.7-kV/1-kA IGBT power...

  17. Effect of Short-Circuit Faults in the Back-to-Back Power Electronic Converter and Rotor Terminals on the Operational Behavior of the Doubly-Fed Induction Generator Wind Energy Conversion System

    Directory of Open Access Journals (Sweden)

    Dimitrios G. Giaourakis

    2015-02-01

    Full Text Available This paper deals with the operational behavior of the Doubly-Fed Induction Generator Wind Energy Conversion System under power electronic converter and rotor terminals faulty conditions. More specifically, the effect of the short-circuit fault both in one IGBT of the back-to-back power electronic converter and in rotor phases on the overall system behavior has been investigated via simulation using a system of 2 MW. Finally, the consequences of these faults have been evaluated.

  18. Rated-voltage enhancement by fast-breaking of the fault current for a resistive superconducting fault current limiter component

    International Nuclear Information System (INIS)

    Park, C.-R.; Kim, M.-J.; Yu, S.-D.; Yim, S.-W.; Kim, H.-R.; Hyun, O.-B.

    2010-01-01

    Performance of a resistive superconducting fault current limiter (SFCL) component is usually limited by temperature rise associated with energy input by fault current application during a fault. Therefore, it is expected that short application of the fault current may enhance the power ratings of the component. This can be accomplished by a combination of a HTS component and a mechanical switch. The fast switch (FS) developed recently enables the fault duration to be as short as 1/2 cycle after a fault. Various second-generation (2G) high temperature superconductors (HTS) and YBCO thin films have been tested. The relation between the rated voltage V and the fault duration time t was found to be V 2 ∼ t -1 . Based upon the relation, we predict that when the FS break the fault current within 1/2 cycle after a fault, the amount of HTS components required to build an SFCL can be reduced by as much as about 60%, of that when breaking the fault current at three cycles.

  19. MPPT Technique Based on Current and Temperature Measurements

    Directory of Open Access Journals (Sweden)

    Eduardo Moreira Vicente

    2015-01-01

    Full Text Available This paper presents a new maximum power point tracking (MPPT method based on the measurement of temperature and short-circuit current, in a simple and efficient approach. These measurements, which can precisely define the maximum power point (MPP, have not been used together in other existing techniques. The temperature is measured with a low cost sensor and the solar irradiance is estimated through the relationship of the measured short-circuit current and its reference. Fast tracking speed and stable steady-state operation are advantages of this technique, which presents higher performance when compared to other well-known techniques.

  20. Prevalence of current patterns and predictive trends of multidrug-resistant Salmonella Typhi in Sudan

    Directory of Open Access Journals (Sweden)

    Ayman A. Elshayeb

    2017-11-01

    Full Text Available Abstract Background Enteric fever has persistence of great impact in Sudanese public health especially during rainy season when the causative agent Salmonella enterica serovar Typhi possesses pan endemic patterns in most regions of Sudan - Khartoum. Objectives The present study aims to assess the recent state of antibiotics susceptibility of Salmonella Typhi with special concern to multidrug resistance strains and predict the emergence of new resistant patterns and outbreaks. Methods Salmonella Typhi strains were isolated and identified according to the guidelines of the International Standardization Organization and the World Health Organization. The antibiotics susceptibilities were tested using the recommendations of the Clinical Laboratories Standards Institute. Predictions of emerging resistant bacteria patterns and outbreaks in Sudan were done using logistic regression, forecasting linear equations and in silico simulations models. Results A total of 124 antibiotics resistant Salmonella Typhi strains categorized in 12 average groups were isolated, different patterns of resistance statistically calculated by (y = ax − b. Minimum bactericidal concentration’s predication of resistance was given the exponential trend (y = n ex and the predictive coefficient R2 > 0 < 1 are approximately alike. It was assumed that resistant bacteria occurred with a constant rate of antibiotic doses during the whole experimental period. Thus, the number of sensitive bacteria decreases at the same rate as resistant occur following term to the modified predictive model which solved computationally. Conclusion This study assesses the prediction of multi-drug resistance among S. Typhi isolates by applying low cost materials and simple statistical methods suitable for the most frequently used antibiotics as typhoid empirical therapy. Therefore, bacterial surveillance systems should be implemented to present data on the aetiology and current

  1. Estudo de alguns parâmetros básicos da soldagem GMAW com transferência por curto-circuito Evaluation of basic parameters of short-circuit GMA welding

    Directory of Open Access Journals (Sweden)

    Paulo J. Modenesi

    2011-03-01

    these limitations of GMA welding, the authors of the present work have been working on the development of a mathematical model to simulate the variation of operational and electrical parameters during welding. This paper aims to evaluate methodologies to determine two key variables of this model (the electrode electrical resistivity and the sum of the voltage drops in the arc anode and cathode regionsin short-circuit welding. Experimental trials were performed in a mechanized jig by depositing bead-onplate welds on low-carbon steel bars. Methodologies to evaluate those variables were developed based in proposals from the literature. Experimental details of these methodologies are analyzed and their results are compared to results from the literature. These procedures are evaluated, compared with data from the literature and new procedures are proposed to estimate those parameters and the contact resistance between the contact tip and the electrode. Results suggest values between 6 and 9 Ω for this last parameter.

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

    CERN Document Server

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

    2003-01-01

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

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

    Science.gov (United States)

    Teverovsky, Alexander A.

    2016-01-01

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

  4. Overcoming resistance to targeted therapies in NSCLC: current approaches and clinical application.

    Science.gov (United States)

    Maione, Paolo; Sacco, Paola Claudia; Sgambato, Assunta; Casaluce, Francesca; Rossi, Antonio; Gridelli, Cesare

    2015-09-01

    The discovery that a number of aberrant tumorigenic processes and signal transduction pathways are mediated by druggable protein kinases has led to a revolutionary change in nonsmall cell lung cancer (NSCLC) treatment. Epidermal growth factor receptor (EGFR) and anaplastic lymphoma kinase (ALK) are the targets of several tyrosine kinase inhibitors (TKIs), some of them approved for treatment and others currently in clinical development. First-generation agents offer, in target populations, a substantial improvement of outcomes compared with standard chemotherapy in the treatment of advanced NSCLC. Unfortunately, drug resistance develops after initial benefit through a variety of mechanisms. Novel generation EGFR and ALK inhibitors are currently in advanced clinical development and are producing encouraging results in patients with acquired resistance to previous generation agents. The search for new drugs or strategies to overcome the TKI resistance in patients with EGFR mutations or ALK rearrangements is to be considered a priority for the improvement of outcomes in the treatment of advanced NSCLC.

  5. Low-energy Resistive Random Access Memory Devices with No Need for a Compliance Current

    Science.gov (United States)

    Xu, Zedong; Yu, Lina; Wu, Yong; Dong, Chang; Deng, Ning; Xu, Xiaoguang; Miao, J.; Jiang, Yong

    2015-01-01

    A novel resistive random access memory device is designed with SrTiO3/ La2/3Sr1/3MnO3 (LSMO)/MgAl2O4 (MAO)/Cu structure, in which metallic epitaxial LSMO is employed as the bottom electrode rather than traditional metal materials. In this device, the critical external compliance current is no longer necessary due to the high self-resistance of LSMO. The LMSO bottom electrode can act as a series resistor to offer a compliance current during the set process. Besides, the device also has excellent switching features which are originated in the formation of Cu filaments under external voltage. Therefore it provides the possibility of reducing power consumption and accelerating the commercialization of resistive switching devices. PMID:25982101

  6. Lithological characterization of a contaminated site using Direct current resistivity and time domain Induced Polarization

    DEFF Research Database (Denmark)

    Maurya, Pradip Kumar; Fiandaca, Gianluca; Auken, Esben

    study a large contaminated site in Denmark was investigated using direct current resistivity and time domain induced polarization (DCIP). For this purpose 14 profiles were collected alongside a stream in order to investigate the contamination and delineate the lithological units. 2D inversion using...

  7. Effects of Hall current and electrical resistivity on the stability of gravitating anisotropic quantum plasma

    Science.gov (United States)

    Bhakta, S.; Prajapati, R. P.

    2018-02-01

    The effects of Hall current and finite electrical resistivity are studied on the stability of uniformly rotating and self-gravitating anisotropic quantum plasma. The generalized Ohm's law modified by Hall current and electrical resistivity is used along with the quantum magnetohydrodynamic fluid equations. The general dispersion relation is derived using normal mode analysis and discussed in the parallel and perpendicular propagations. In the parallel propagation, the Jeans instability criterion, expression of critical Jeans wavenumber, and Jeans length are found to be independent of non-ideal effects and uniform rotation but in perpendicular propagation only rotation affects the Jeans instability criterion. The unstable gravitating mode modified by Bohm potential and the stable Alfven mode modified by non-ideal effects are obtained separately. The criterion of firehose instability remains unaffected due to the presence of non-ideal effects. In the perpendicular propagation, finite electrical resistivity and quantum pressure anisotropy modify the dispersion relation, whereas no effect of Hall current was observed in the dispersion characteristics. The Hall current, finite electrical resistivity, rotation, and quantum corrections stabilize the growth rate. The stability of the dynamical system is analyzed using the Routh-Hurwitz criterion.

  8. Disease resistance breeding in rose: current status and potential of biotechnological tools.

    Science.gov (United States)

    Debener, Thomas; Byrne, David H

    2014-11-01

    The cultivated rose is a multispecies complex for which a high level of disease protection is needed due to the low tolerance of blemishes in ornamental plants. The most important fungal diseases are black spot, powdery mildew, botrytis and downy mildew. Rose rosette, a lethal viral pathogen, is emerging as a devastating disease in North America. Currently rose breeders use a recurrent phenotypic selection approach and perform selection for disease resistance for most pathogen issues in a 2-3 year field trial. Marker assisted selection could accelerate this breeding process. Thus far markers have been identified for resistance to black spot (Rdrs) and powdery mildew and with the ability of genotyping by sequencing to generate 1000s of markers our ability to identify markers useful in plant improvement should increase exponentially. Transgenic rose lines with various fungal resistance genes inserted have shown limited success and RNAi technology has potential to provide virus resistance. Roses, as do other plants, have sequences homologous to characterized R-genes in their genomes, some which have been related to specific disease resistance. With improving next generation sequencing technology, our ability to do genomic and transcriptomic studies of the resistance related genes in both the rose and the pathogens to reveal novel gene targets to develop resistant roses will accelerate. Finally, the development of designer nucleases opens up a potentially non-GMO approach to directly modify a rose's DNA to create a disease resistant rose. Although there is much potential, at present rose breeders are not using marker assisted breeding primarily because a good suite of marker/trait associations (MTA) that would ensure a path to stable disease resistance is not available. As our genomic analytical tools improve, so will our ability to identify useful genes and linked markers. Once these MTAs are available, it will be the cost savings, both in time and money, that will

  9. Research on influence of parasitic resistance of InGaAs solar cells under continuous wave laser irradiation

    Science.gov (United States)

    Li, Guangji; Zhang, Hongchao; Zhou, Guanglong; Lu, Jian; Zhou, Dayong

    2017-06-01

    InGaAs solar cells were irradiated by 1060-1080nm continuous wave (CW) laser, and studied the laser-electrical conversion and damage experiment with the power density as 97mW/cm2 and 507W/cm2 respectively. The result indicated that there is no obvious damage phenomenon but air layer appeared in the damaged region, and there is no direct relationship between the area and the extent of damage. Moreover, the p-n junction in the damage zone was destroyed, lost the ability of photoelectric conversion. The region acts as a resistance between the two electrodes, resulting in an increase in the leakage current of the solar cells and a decrease in the parallel resistance, which is the main reason leading to the decline of open circuit voltage, short circuit current and conversion efficiency. This paper would provide a reference for wireless energy transmission and the subsequent laser damage of solar cells.

  10. Data fusion analysis of a surface direct-current resistivity and well pick data set

    International Nuclear Information System (INIS)

    Clayton, E.A.; Lewis, R.E.

    1995-09-01

    Pacific Northwest Laboratory (PNL) has been tasked with testing, debugging, and refining the Hanford Site data fusion workstation (DFW), with the assistance of Coleman Research Corporation (CRC), before delivering the DFW to the environmental restoration client at the Hanford Site. Data fusion is the mathematical combination (or fusion) of disparate data sets into a single interpretation. The data fusion software used in this study was developed by CRC. This report discusses the results of evaluating a surface direct-current (dc) resistivity and well-pick data set using two methods: data fusion technology and commercially available software (i.e., RESIX Plus from Interpex Ltd., Golden, Colorado), the conventional method of analysis. The report compares the two technologies; describes the survey, procedures, and results; and includes conclusions and recommendations. The surface dc resistivity and well-pick data set had been acquired by PNL from a study performed in May 1993 at Eielson Air Force Base near Fairbanks, Alaska. The resistivity survey data were acquired to map the top of permafrost in support of a hydrogeologic study. This data set provided an excellent opportunity to test and refine the dc resistivity capabilities of the DFW; previously, the data fusion software was untested on dc resistivity data. The DFW was used to evaluate the dc resistivity survey data and to produce a 3-dimensional earth model of the study area

  11. A single electrode voltage, current- and patch-clamp amplifier with complete stable series resistance compensation.

    Science.gov (United States)

    Strickholm, A

    1995-01-01

    An input headstage for single electrode voltage and current clamping is described which permits selecting desired operational modes during an experiment. These include cell attached or whole cell patch clamping, single micro-electrode voltage or current clamping, potential recording, iontophoresis and voltammetry. Input electrode series resistance with the electrode inserted in a cell or during whole cell patch clamping can be measured at any time. The unique circuitry allows complete compensation of the series resistance with high frequency response. The input series electrode resistance can also vary considerably around an initially set 100% compensation with intrinsic stability. An accelerator 'supercharger' or 'booster circuit' is included which can shorten the rise time of membrane potential to the command potential by a hundredfold. This improves the recording of early ion channel currents. Feedback resistors are selected remotely for the specific experimental need. Signal resolution in patch clamping is that expected from the thermal noise of the feedback resistor and electrode to membrane seal resistance. This headstage circuitry design thus allows interchangeable modes of operation and parameters during an experiment to obtain optimal conditions for signal detection and frequency response.

  12. Power flow analysis and optimal locations of resistive type superconducting fault current limiters.

    Science.gov (United States)

    Zhang, Xiuchang; Ruiz, Harold S; Geng, Jianzhao; Shen, Boyang; Fu, Lin; Zhang, Heng; Coombs, Tim A

    2016-01-01

    Based on conventional approaches for the integration of resistive-type superconducting fault current limiters (SFCLs) on electric distribution networks, SFCL models largely rely on the insertion of a step or exponential resistance that is determined by a predefined quenching time. In this paper, we expand the scope of the aforementioned models by considering the actual behaviour of an SFCL in terms of the temperature dynamic power-law dependence between the electrical field and the current density, characteristic of high temperature superconductors. Our results are compared to the step-resistance models for the sake of discussion and clarity of the conclusions. Both SFCL models were integrated into a power system model built based on the UK power standard, to study the impact of these protection strategies on the performance of the overall electricity network. As a representative renewable energy source, a 90 MVA wind farm was considered for the simulations. Three fault conditions were simulated, and the figures for the fault current reduction predicted by both fault current limiting models have been compared in terms of multiple current measuring points and allocation strategies. Consequently, we have shown that the incorporation of the E - J characteristics and thermal properties of the superconductor at the simulation level of electric power systems, is crucial for estimations of reliability and determining the optimal locations of resistive type SFCLs in distributed power networks. Our results may help decision making by distribution network operators regarding investment and promotion of SFCL technologies, as it is possible to determine the maximum number of SFCLs necessary to protect against different fault conditions at multiple locations.

  13. Quality evaluation of concrete under compacting by vibration using resistance of electro current

    International Nuclear Information System (INIS)

    Nozaki, Yoshisugu

    2006-01-01

    Quality of concrete in structures is affected not only quality of materials; i.e. fresh concrete delivered to site but also placing and compaction works. Factors related to the latter are not studied minutely, and the works in site are judged and controlled by skilled person under his experience, and these process are said to the neck in QC and rationalization in construction site. The study to develop the evaluation system of fresh concrete quality is described in the paper. In the experiment, electrode was attached to form work and resistance of electro current was recorded while vibrating. It can recognized that resistance is closely related to internal quality of concrete, so the resistance may be the effective index to know optimum compaction time in placing work.

  14. Quality evaluation of concrete under compacting by vibration using resistance of electro current

    International Nuclear Information System (INIS)

    Nozaki, Yoshisugu

    2006-01-01

    Quality of concrete in structures is affected not only quality of materials; i.e. fresh concrete delivered to site but also placing and compaction works. Factors related to the latter are not studied minutely, and the works in site are judged and controlled by skilled person under his experience, and these process are said to the neck in QC and rationalization in construction site. The study to develop the evaluation system of fresh concrete quality is described in the paper, In the experiment, electrode was attached to formwork and resistance of electro current was recorded while vibrating. It can recognized that resistance is closely related to internal quality of concrete, so the resistance may be the effective index to know optimum compaction time in placing work.

  15. Photo-induced current transient spectroscopy for high-resistivity neutron-transmutation-doped silicon

    International Nuclear Information System (INIS)

    Tokuda, Yutaka; Inoue, Yajiro; Usami, Akira

    1987-01-01

    Defects in high-resistivity neutron-transmutation-doped (NTD) silicon prior to annealing were studied by photo-induced current transient spectroscopy (PICTS). The thermal-neutron fluence was 9.5 x 10 17 cm -2 to give a resistivity of about 30 Ω after annealing, and the fast-neutron fluence was 9.5 x 10 16 cm -2 . Four traps with thermal emission activation energies of 0.15, 0.41. 0.47 and 0.50 eV were observed in NTD silicon. A trap with the thermal emission activation energy of 0.15 eV was considered to correspond to the divacancy. Although the clustered nature of the defects was observed, PICTS measurements suggest that the material state of high-resistivity NTD silicon is still crystalline and not amorphous. (author)

  16. High Dynamic Magnetic Beam Current Measurements by Means of Optimised Magneto-Resistance (MR) Sensor Engineering

    CERN Document Server

    Hape, M; Ricken, W

    2005-01-01

    The GSI-FAIR project (facility for antiprotons and ion research) will comprehend DC currents up to around 5 A in the SIS 100 synchrotron and after bunch compression down to 50 ns pulse length the peak currents will reach up to 100 A. To meet these higher demands of beam current measurements new sensor techniques are foreseen. The measurement device itself will be designed in form of a clip-on ampere-meter. The air gap of the flux concentrator is assumed to be around 5 mm and thus, the estimated maximum field therein is around 30 mT for a beam current of 100 A peak. The resolution of this device is aimed to be 1 mA in beam current, corresponding to a system dynamic of around 105. This high demands of beam current measurement require more sophisticated sensor types than just using a Hall probe. The characteristics of AMR (anisotropic magneto-resistance), GMR (giant magneto-resistance) and GMI (giant magneto-impedance) sensors like hysteresis, linearity and sensitivity have been measured within the magnetic fiel...

  17. [Current antibiotic resistance profile of uropathogenic Escherichia coli strains and therapeutic consequences].

    Science.gov (United States)

    El Bouamri, M C; Arsalane, L; Kamouni, Y; Yahyaoui, H; Bennouar, N; Berraha, M; Zouhair, S

    2014-12-01

    Urinary tract infections (UTI) are a very common reason for consultation and prescription in current practice. Excessive or inappropriate use of antibiotics in treating urinary tract infections is responsible for the emergence and spread of multiresistant uropathogenic bacteria. To evaluate the isolation frequency and antibiotic resistance of uropathogenic Escherichia coli strains isolated at the Marrakech region. We conducted a retrospective study over a period of three years (from 1st January 2010 to 31 December 2012). It included all non-redundant uropathogenic E. coli strains isolated in the microbiology laboratory of the Avicenne hospital of Marrakech, Morocco. During this study, 1472 uropathogenic enterobacteriaceae were isolated including 924 non-repetitive E. coli strains, an overall isolation frequency of 63%. Antibiotic resistance of isolated E. coli strains showed resistance rates to amoxicillin (65%), sulfamethoxazole-triméthropime (55%), amoxicillin-clavulanic acid (43%), ciprofloxacin (22%), gentamicin (14%), nitrofurans (11%), amikacin (8%) and fosfomycin (7%). The number of E. coli strains resistant to C3G by ESBL production was 67, an average frequency of 4.5% of all isolated uropathogenic enterobacteria. The associated antibiotic resistance in the case of ESBL-producing E. coli were 82% for ciprofloxacin, 76% for sulfamethozole trimethoprim, 66% for gentamicin and 56% for amikacin. No resistance to imipenem was recorded for the isolated E. coli strains, which represents an imipenem sensitivity of 100%. Antibiotic resistance of uropathogenic E. coli strains limits treatment options and therefore constitutes a real public health problem. The regular updating of antibiotic susceptibility statistics of E. coli strains allows a better adaptation of the probabilistic antibiotic therapy to local epidemiological data. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  18. Current Bias Induced Negative Magneto-Resistance in Superconducting Tantalum Thin Films

    Science.gov (United States)

    Park, Sun-Gyu; Kim, Eunseong

    2014-03-01

    Negative Magneto-Resistance (MR) of 2D superconducting thin films has received attentions because the decreasing resistance with increasing magnetic field cannot be simply understood by conventional superconductivity. This behavior was ascribed to localized bosons, indicating the existence of a Bose insulator (BI) phase. We found negative MR within a range of dc current bias in tantalum thin films, whereas no negative MR appears without bias. We measured Rxx and Rxy simultaneously as functions of current bias and magnetic field and construct the phase diagram at T =0 limit. We found that the DC biased negative MR in Ta thin film shows substantially different characteristics from those of reported no biased negative MR. We also found that the induced BI can be understood by the vortex instability state. We gratefully acknowledge the financial support by the National Research Foundation of Korea through the Creative Research Initiatives.

  19. Hysteresis and negative differential resistance of the current-voltage characteristic of a water bridge

    Science.gov (United States)

    Oshurko, V. B.; Fedorov, A. N.; Ropyanoi, A. A.; Fedosov, M. V.

    2014-06-01

    It is found experimentally that the properties of nanoporous ion-exchange membranes (hysteresis of the current-voltage characteristic in the solution and negative differential resistance), which have been discussed in recent years, are not associated with the properties of the membrane. It is shown that these effects are also observed in a floating water bridge and in water-filled tubes and are apparently determined by the geometrical shape of the liquid conductor. The observed effects are explained qualitatively.

  20. Market potential of superconductor current limiters; Marktpotential von supraleitenden Strombegrenzern

    Energy Technology Data Exchange (ETDEWEB)

    Lakner, M.; Braun, D. [ABB Schweiz AG, Corporate Research, Baden-Daettwil (Switzerland); Schnyder, G.; Mauchle, P. [Schnyder Ingenieure AG, Huenenberg (Switzerland)

    2003-07-01

    This final report for the Swiss Federal Office of Energy describes the two concepts - 'resistive' and 'inductive' - used for Superconducting Fault Current Limiters (SCFCL) that utilise the transition from zero to finite resistance to limit short-circuit currents. The main advantages of SCFCL are compared to other current-limiting technologies: They can limit any type of prospective fault current, operate fail-safe, be self-triggered and self-restoring. Their main disadvantage - the cooling effort necessary - is also discussed. The application possibilities of SCFCL were investigated by simulating the impact on utility and industrial grids. Applications of SCFCL such as the coupling of medium-voltage grids and their use in series with a circuit-breaker on the secondary side of a substation transformer are discussed. It is also shown that, by using fault current limiters, considerable cost savings can be made, especially in connection with new installations or the extension of existing plants.

  1. Optimum design of matrix fault current limiters using the series resistance connected with shunt coil

    Science.gov (United States)

    Chung, D. C.; Choi, H. S.; Lee, N. Y.; Nam, G. Y.; Cho, Y. S.; Sung, T. H.; Han, Y. H.; Kim, B. S.; Lim, S. H.

    2007-10-01

    In this paper we described the improved design for the matrix fault current limiters (MFCL). To do this, we used thin film-type superconducting elements. therefore it means that we can make the MFCL with minimized size and high switching speed because of the high current density and the high indexing value of superconducting thin film. Also we could minimize the bulky shunt coil using the connection of a series resistance with a shunt coil. Also we could effectively block up a leakage current in shunt coils under no-fault condition and simply control total impedances of a current-limiting part using this method. After we designed an appropriated 1 × 2 basic MFCL module with an applied voltage of 160 V, we enlarged it to a 2 × 2 MFCL module and a 3 × 2 MFCL module where applied voltages were 320 V and 480 V, respectively. Experimental results for our MFCL were reported in terms of various fault currents, variation of series resistance and so on. We think that these methods will be useful in the optimum design of an m × n MFCL.

  2. Optimum design of matrix fault current limiters using the series resistance connected with shunt coil

    International Nuclear Information System (INIS)

    Chung, D.C.; Choi, H.S.; Lee, N.Y.; Nam, G.Y.; Cho, Y.S.; Sung, T.H.; Han, Y.H.; Kim, B.S.; Lim, S.H.

    2007-01-01

    In this paper we described the improved design for the matrix fault current limiters (MFCL). To do this, we used thin film-type superconducting elements. therefore it means that we can make the MFCL with minimized size and high switching speed because of the high current density and the high indexing value of superconducting thin film. Also we could minimize the bulky shunt coil using the connection of a series resistance with a shunt coil. Also we could effectively block up a leakage current in shunt coils under no-fault condition and simply control total impedances of a current-limiting part using this method. After we designed an appropriated 1 x 2 basic MFCL module with an applied voltage of 160 V, we enlarged it to a 2 x 2 MFCL module and a 3 x 2 MFCL module where applied voltages were 320 V and 480 V, respectively. Experimental results for our MFCL were reported in terms of various fault currents, variation of series resistance and so on. We think that these methods will be useful in the optimum design of an m x n MFCL

  3. Elucidating the interplay between dark current coupling and open circuit voltage in organic photovoltaics

    KAUST Repository

    Erwin, Patrick

    2011-01-01

    A short series of alkyl substituted perylenediimides (PDIs) with varying steric bulk are used to demonstrate the relationship between molecular structure, materials properties, and performance characteristics in organic photovoltaics. Devices were made with the structure indium tin oxide/copper phthalocyanine (200 Å)/PDI (200 Å)/bathocuproine (100 Å)/aluminum (1000 Å). We found that PDIs with larger substituents produced higher open circuit voltages (VOC\\'s) despite the donor acceptor interface gap (Δ EDA) remaining unchanged. Additionally, series resistance was increased simultaneously with VOC the effect of reducing short circuit current, making the addition of steric bulk a tradeoff that needs to be balanced to optimize power conversion efficiency. © 2011 American Institute of Physics.

  4. Current Status and Challenges in Identifying Disease Resistance Genes in Brassica napus

    Directory of Open Access Journals (Sweden)

    Ting Xiang Neik

    2017-11-01

    Full Text Available Brassica napus is an economically important crop across different continents including temperate and subtropical regions in Europe, Canada, South Asia, China and Australia. Its widespread cultivation also brings setbacks as it plays host to fungal, oomycete and chytrid pathogens that can lead to serious yield loss. For sustainable crop production, identification of resistance (R genes in B. napus has become of critical importance. In this review, we discuss four key pathogens affecting Brassica crops: Clubroot (Plasmodiophora brassicae, Blackleg (Leptosphaeria maculans and L. biglobosa, Sclerotinia Stem Rot (Sclerotinia sclerotiorum, and Downy Mildew (Hyaloperonospora parasitica. We first review current studies covering prevalence of these pathogens on Brassica crops and highlight the R genes and QTL that have been identified from Brassica species against these pathogens. Insights into the relationships between the pathogen and its Brassica host, the unique host resistance mechanisms and how these affect resistance outcomes is also presented. We discuss challenges in identification and deployment of R genes in B. napus in relation to highly specific genetic interactions between host subpopulations and pathogen pathotypes and emphasize the need for common or shared techniques and research materials or tighter collaboration between researchers to reconcile the inconsistencies in the research outcomes. Using current genomics tools, we provide examples of how characterization and cloning of R genes in B. napus can be carried out more effectively. Lastly, we put forward strategies to breed resistant cultivars through introgressions supported by genomic approaches and suggest prospects that can be implemented in the future for a better, pathogen-resistant B. napus.

  5. Current Status and Challenges in Identifying Disease Resistance Genes in Brassica napus

    Science.gov (United States)

    Neik, Ting Xiang; Barbetti, Martin J.; Batley, Jacqueline

    2017-01-01

    Brassica napus is an economically important crop across different continents including temperate and subtropical regions in Europe, Canada, South Asia, China and Australia. Its widespread cultivation also brings setbacks as it plays host to fungal, oomycete and chytrid pathogens that can lead to serious yield loss. For sustainable crop production, identification of resistance (R) genes in B. napus has become of critical importance. In this review, we discuss four key pathogens affecting Brassica crops: Clubroot (Plasmodiophora brassicae), Blackleg (Leptosphaeria maculans and L. biglobosa), Sclerotinia Stem Rot (Sclerotinia sclerotiorum), and Downy Mildew (Hyaloperonospora parasitica). We first review current studies covering prevalence of these pathogens on Brassica crops and highlight the R genes and QTL that have been identified from Brassica species against these pathogens. Insights into the relationships between the pathogen and its Brassica host, the unique host resistance mechanisms and how these affect resistance outcomes is also presented. We discuss challenges in identification and deployment of R genes in B. napus in relation to highly specific genetic interactions between host subpopulations and pathogen pathotypes and emphasize the need for common or shared techniques and research materials or tighter collaboration between researchers to reconcile the inconsistencies in the research outcomes. Using current genomics tools, we provide examples of how characterization and cloning of R genes in B. napus can be carried out more effectively. Lastly, we put forward strategies to breed resistant cultivars through introgressions supported by genomic approaches and suggest prospects that can be implemented in the future for a better, pathogen-resistant B. napus. PMID:29163558

  6. Estimation of the annual rate of interruptions in a industrial plant resulting from short-circuits in the utilities networks; Estimativa da taxa anual de interrupcoes numa planta industrial causadas por curtos-circuitos nas redes das concessionarias

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Antonio Guilherme Garcia; Ross, Ricardo Penido Dutt; Sollero, Raul Balbi [Centro de Pesquisas de Energia Eletrica, Rio de Janeiro, RJ (Brazil). E-mail: aggl@cepel.br

    1999-07-01

    This paper presents the CEPEL experience in interruptions and voltage sags analysis and the supplier system characteristic influence - radial, parallel lines, multiple feeding, etc - on the magnitude of the voltage sags detected inside the facility. The paper shows a technique for the estimation of the significant voltage sags (below 70 % of the nominal voltage) in a industry based on simulations of short-circuit in the network, and the existent data of the number of interruptions on transmission lines per each 100 km, per year.

  7. Reduction of on-resistance and current crowding in quasi-vertical GaN power diodes

    Science.gov (United States)

    Zhang, Yuhao; Sun, Min; Piedra, Daniel; Hennig, Jonas; Dadgar, Armin; Palacios, Tomás

    2017-10-01

    This paper studies the key parameters affecting on-resistance and current crowding in quasi-vertical GaN power devices by experiment and simulation. The current distribution in the drift region, n--GaN, was found to be mainly determined by the sheet resistance of the current spreading layer, n+-GaN. The actual on-resistance of the drift region significantly depends on this current distribution rather than the intrinsic resistivity of the drift layer. As a result, the total specific on-resistance of quasi-vertical diodes shows a strong correlation with the device area and sheet resistance of the current spreading layer. By reducing the sheet resistance of the current spreading layer, the specific on-resistance of quasi-vertical GaN-on-Si power diodes has been reduced from ˜10 mΩ.cm2 to below 1 mΩ.cm2. Design space of the specific on-resistance at different breakdown voltage levels has also been revealed in optimized quasi-vertical GaN power diodes.

  8. Molecular epidemiology of drug-resistant Neisseria gonorrhoeae in Russia (Current Status, 2015).

    Science.gov (United States)

    Kubanov, Alexey; Vorobyev, Denis; Chestkov, Aleksandr; Leinsoo, Arvo; Shaskolskiy, Boris; Dementieva, Ekaterina; Solomka, Viktoria; Plakhova, Xenia; Gryadunov, Dmitry; Deryabin, Dmitriy

    2016-08-09

    The widespread distribution of Neisseria gonorrhoeae strains that are resistant to previously used and clinically implemented antibiotics is a significant global public health problem. In line with WHO standards, the national Gonococcal Antimicrobial Surveillance Programme (RU-GASP) has been in existence in Russia since 2004; herein, the current status (2015) is described, including associations between N. gonorrhoeae antimicrobial susceptibility, primary genetic resistance determinants and specific strain sequence types. A total of 124 N. gonorrhoeae strains obtained from 9 regions in Russia in 2015 were examined using N. gonorrhoeae Multi-Antigen Sequence Typing (NG-MAST), an antimicrobial susceptibility test according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria and an oligonucleotide microarray for the identification of mutations in the penA, ponA, rpsJ, gyrA and parC genes responsible for penicillin G, tetracycline, and fluoroquinolone resistance. Genogroup (G) isolates were evaluated based on their porB and tbpB sequence types (STs). NG-MAST analysis showed a diversified population of N. gonorrhoeae in Russia with 58 sequence types, 35 of which were described for the first time. The STs 807, 1544, 1993, 5714, 9476 and 12531, which were typical for some Russian Federation regions and several countries of the former Soviet Union, were represented by five or more isolates. The internationally widespread ST 1407 was represented by a single strain in the present study. Division into genogroups facilitated an exploration of the associations between N. gonorrhoeae sequence type, antimicrobial resistance spectra and genetic resistance determinant contents. Preliminarily susceptible (G-807, G-12531) and resistant (G-5714, G-9476) genogroups were revealed. The variability in the most frequently observed STs and genogroups in each participating region indicated geographically restricted antimicrobial susceptibility in N. gonorrhoeae

  9. Current and prospective treatments for multidrug-resistant gram-positive infections.

    Science.gov (United States)

    Rybak, Jeffrey M; Barber, Katie E; Rybak, Michael J

    2013-10-01

    Staphylococcus aureus and Enterococcus spp. are two of the most common organisms causing nosocomial infections today; and are consistently associated with high mortality rates (approximately 20 and 44%, respectively). Resistance among these pathogens to first line agents such as methicillin and vancomycin continues to rise while isolates with reduced susceptibility to newer agents including linezolid and daptomycin continue to emerge, representing a serious concern for clinicians. Mechanisms of action and resistance as well as in vitro and clinical experience in the treatment of resistant staphylococci and enterococci with currently available agents are discussed. Additionally, novel combination regimens showing enhanced efficacy and available data pertaining to prospective therapies including solithromycin, tedizolid, dalbavancin and oritavancin will be covered. With an increase in organisms displaying reduced susceptibility to vancomycin and the associated treatment failures, the significance of alternative therapies such as daptomycin, linezolid, ceftaroline, and prospective anti-gram-positive agents is on the rise. As our understanding of antimicrobial pharmacokinetic-pharmacodynamics principles continues to evolve, the selection of highly effective agents and optimization of dosages may lead to improved patient outcomes and delay the development of resistance.

  10. Methicillin-resistant Staphylococcus aureus prevalence: Current susceptibility patterns in Trinidad

    Directory of Open Access Journals (Sweden)

    Land Michael

    2006-05-01

    Full Text Available Abstract Background Methicillin-resistant Staphylococcus aureus (MRSA has become one of the most widespread causes of nosocomial infections worldwide. Recently, reports have emerged that S. aureus strains recovered from community-acquired infections are also methicillin-resistant. This study was undertaken to analyze the prevalence of methicillin resistance among isolates at a regional hospital in Trinidad, and document the current resistance profile of MRSA and methicillin-sensitive Staphylococcus aureus (MSSA to the commonly used anti-staphylococcal agents. Methods Over a 6-year period we analyzed 2430 isolates of S. aureus strains recovered from various clinical sources, from hospital and community practices. Antimicrobial susceptibility testing was done according to guideline recommendations of the National Committee for Clinical Laboratory Standards. Results The prevalence of MRSA from surgical/burn wounds, urine and pus/abscess were 60.1%, 15.5% and 6.6%, respectively. The major sources of MSSA were surgical/burn wounds, pus/abscess and upper respiratory tract specimens with rates of 32.9%, 17.1% and 14.3%, respectively. The greatest prevalence of resistance of MRSA was seen for erythromycin (86.7%, and clindamycin (75.3%. Resistance rates among MSSA were highest for ampicillin (70%. Resistance rates for tetracycline were similar among both MRSA (78.7% and MSSA (73.5%. The MRSA recovery rates from nosocomial sources (20.8% was significantly higher than that of previous years (12.5% (p Conclusion The prevalence of MRSA in the hospital increased from 12.5% in 1999 to 20.8% in 2004. Most isolates were associated with infected surgical/burn wounds which may have become infected via the hands of HCPs during dressing exercises. Infection control measures aimed at the proper hand hygiene procedures may interrupt the spread of MRSA. HCPs may also be carriers of MRSA in their anterior nares. Surveillance cultures of both patients and HCPs may help

  11. Current methodologies on genotyping for nosocomial pathogen methicillin-resistant Staphylococcus aureus (MRSA).

    Science.gov (United States)

    Miao, Jian; Chen, Lequn; Wang, Jingwen; Wang, Wenxin; Chen, Dingqiang; Li, Lin; Li, Bing; Deng, Yang; Xu, Zhenbo

    2017-06-01

    Methicillin-resistant Staphylococcus aureus (MRSA) is a common pathogen in hospitals and the community. As the rapid spread and wide distribution of antimicrobial resistance (such as MRSA), treatment for infectious diseases caused by microorganisms has become a vital threat. Thus, early identification and genotyping are essential for further therapeutic treatment and the control of rapid expansion of MRSA. In combination with applications and data feedbacks, this review focused on the currently available molecular-based assays on their utility and performance for rapid typing of MRSA, especially on effective molecular-based methods. Besides, a common mobile element SCCmec and prevalence of HA-MRSA, LA-MRSA and CA-MRSA were introduced in this review in order to provide a more complete profile of MRSA. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Resistive switching in individual ZnO nanorods: delineating the ionic current by photo-stimulation

    Science.gov (United States)

    Bandopadhyay, K.; Prajapati, K. N.; Mitra, J.

    2018-03-01

    Resistive switching in nanostructured metal oxide semiconductors has been broadly understood to originate from the dynamics of its native point defects. Experimental results of switching observed in individual n-ZnO nanorods grown on a p-type polymer is presented along with an empirical model describing the underlying defect dynamics necessary to observe bi-polar switching. Selective photo excitation of electrons into the defect states delineates the incidence and role of an ionic current in the switching behavior. The understanding further extends to the observance of a negative differential resistance regime that is often coincident in such systems. The analysis not only unifies the underlying physics of the two phenomena but also offers further confidence in the proposed mechanism. We conclude by demonstrating that the effective memresistance of such devices is a strong function of the operating bias and identify parameters that optimize switching performance.

  13. Shaft MisalignmentDetectionusing Stator Current Monitoring

    OpenAIRE

    Alok Kumar Verma, Somnath Sarangi and M.H. Kolekar

    2013-01-01

    This paper inspects the misaligned of shaft by usingdiagnostic medium such as current and vibration.Misalignments in machines can cause decrease inefficiency and in the long-run it may cause failurebecause of unnecessary vibration, stress on motor,bearings and short-circuiting in stator and rotorwindings.In this study, authors investigate the onsetof instability on a shaft mounted on journal bearings.Shaft displacement and stator current samples duringmachine run up under misaligned condition...

  14. Passive measurement of flux nucleation in the current-induced resistive state of type I superconductors

    International Nuclear Information System (INIS)

    Selig, K.P.; Chimenti, D.E.; Huebener, R.P.

    1978-01-01

    Flux-tube nucleation rates have been measured in the current-induced resistive state of type I superconducting In films between 1.5 and 2.0 K by a completely passive technique. Indication of periodic nucleation is observed only in narrow regions of sample voltage drop, whose position is a sensitive function of temperature. Frequency bandwidth measurements of the nucleation rate yield a spectral purity of one part in 10 4 within the narrow regions where an experimental signal can be detected. (orig.) [de

  15. Drug development for metastatic castration-resistant prostate cancer: current status and future perspectives.

    Science.gov (United States)

    Lassi, Kiran; Dawson, Nancy A

    2011-04-01

    Prostate cancer represents a third of all newly diagnosed cancers in men in the USA with an estimated incidence of 192,280 cases and 27,360 deaths in 2009. It continues to be a major cause of cancer-related morbidity and mortality, and there is an urgent need for new treatments. Historically, systemic therapy options were limited after progression on docetaxel-based chemotherapy. This article reviews current data on the novel therapeutics demonstrating activity in metastatic castration-resistant prostate cancer and their future role in the treatment of this disease with a poor prognosis.

  16. Effect of parasitic series resistances and spurious currents on the extracted temperature of a bipolar junction transistor.

    Science.gov (United States)

    Mimila-Arroyo, J

    2013-12-01

    Verster's proposition to directly extract the temperature of a bipolar junction transistor using its collector current is widely used. However, the resulting temperature is low accurate even when calibrated. Here, it is demonstrated that the misuse of the emitter current instead of the collector one, because of the presence of spurious currents other than the injection-diffusion one and transistor parasitic series resistances both contribute to the observed inaccuracy. Particularly parasitic series resistances increase the inaccuracy and introduce a strong dependence of the extracted temperature on the collector currents used to extract the temperature; the higher those resistances the higher the inaccuracy. A proposition is made to reduce the effect of those resistances on the inaccuracy of this thermometric element, which allows obtaining a more accurate value on a wider range of the collector probe currents.

  17. Albumin coatings by alternating current electrophoretic deposition for improving corrosion resistance and bioactivity of titanium implants.

    Science.gov (United States)

    Höhn, Sarah; Braem, Annabel; Neirinck, Bram; Virtanen, Sannakaisa

    2017-04-01

    Although Ti alloys are generally regarded to be highly corrosion resistant, inflammatory conditions following surgery can instigate breakdown of the TiO 2 passivation layer leading to an increased metal ion release. Furthermore proteins present in the surrounding tissue will readily adsorb on a titanium surface after implantation. In this paper alternating current electrophoretic deposition (AC-EPD) of bovine serum albumin (BSA) on Ti6Al4V was investigated in order to increase the corrosion resistance and control the protein adsorption capability of the implant surface. The Ti6Al4V surface was characterized with SEM, XPS and ToF-SIMS after long-term immersion tests under physiological conditions and simulated inflammatory conditions either in Dulbecco's Modified Eagle Medium (DMEM) or DMEM supplemented with fetal calf serum (FCS). The analysis showed an increased adsorption of amino acids and proteins from the different immersion solutions. The BSA coating was shown to prevent selective dissolution of the vanadium (V) rich β-phase, thus effectively limiting metal ion release to the environment. Electrochemical impedance spectroscopy measurements confirmed an increase of the corrosion resistance for BSA coated surfaces as a function of immersion time due to the time-dependent adsorption of the different amino acids (from DMEM) and proteins (from FCS) as observed by ToF-SIMS analysis. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. A strategy for protection of high voltage systems using resistive superconducting fault current limiters

    Science.gov (United States)

    Schettino, H. J.; Andrade, R. de, Jr.; Polasek, A.; Kottonau, D.; de Sousa, W. T. B.

    2018-01-01

    This work describes an use of a resistive superconducting fault current limiter (R-SFCL) device based on second generation high temperature superconductors tapes (2G tapes), using a thermal-electrical analogy method to represent heat exchanges. The considered SFCL is supposed to be inserted into the coupling point of a new generation unit to a 12 bar CIGRE benchmark transmission system. The strategy is the investigation of the limitation performance in the high voltage grid by connecting the SFCL at medium voltage grid. We evaluated the performance of the SFCL through the analysis of two cases of faults in different points of the system. Results show that a correct design of the SFCL may effectively limit the contribution of fault currents in the high voltage side. Additionally, it was possible to investigate the behavior of the device internal variables such as the temperature of the superconducting layers for the different cases studied.

  19. Comportamiento del tiempo de duración, la frecuencia de los cortocircuitos y la conductividad eléctrica durante el reencendido del arco en la soldadura SMAW (AC con electrodos E6013 Behavior of short-circuit frequency and duration time and electrical conductivity on arc turn- on during SMAW (AC with E6013 electrodes

    Directory of Open Access Journals (Sweden)

    Alejandro García Rodríguez

    2009-03-01

    Full Text Available El presente trabajo tiene como objetivo la evaluación del comportamiento del tiempo de duración, la frecuencia de los cortocircuitos y la conductividad durante el reencendido del arco en el proceso de soldadura SMAW (Shielded Metal Arc Welding, con corriente alterna y electrodos E6013. El análisis estadístico no-paramétrico garantiza un procesamiento robusto de los datos, atenuando la influencia de valores atípicos y errores derivados del empleo de aproximaciones a distribuciones continuas conocidas. La mediana y la mediana de la desviación absoluta (MAD, respecto a la mediana de los datos, constituyen los estimadores de localización y dispersión utilizados, respectivamente. El electrodo, en el régimen de 160 A, presenta una mayor estabilidad, en el aporte metálico, dada por el menor valor del MAD promedio del período de cortocircuito (39,36 ms y de la duración del cortocircuito (1,43 ms, reafirmada con la presencia de una mayor conductividad eléctrica durante el reencendido (1766,17x10-3 S·s-1.The objective of this work is the valuation of the behavior of short-circuits frequency and duration time and electrical conductivity on arc reigniting in SMAW (Shielded Metal Arc Welding process with alternate current and E6013 electrodes. The non parametric statistic analysis realize a robust data processing, minimizing the outliers influence and mistakes derivates about employ of approximations to well know continues distributions. The median and the median absolute deviation (MAD respect to median of the data are the localization and dispersion estimators used, respectively. The electrode at 160 A present a better stability on metal transference supported on the most little value of MAD for the period of transference (39,36 ms, and the MAD of the short-circuit duration (1,43 ms, according with the presence of a major electric conductivity during the arc reigniting (1766,17x10-3 S·s-1.

  20. Effect of the depth base along the vertical on the electrical parameters of a vertical parallel silicon solar cell in open and short circuit

    Science.gov (United States)

    Sahin, Gokhan; Kerimli, Genber

    2018-03-01

    This article presented a modeling study of effect of the depth base initiating on vertical parallel silicon solar cell's photovoltaic conversion efficiency. After the resolution of the continuity equation of excess minority carriers, we calculated the electrical parameters such as the photocurrent density, the photovoltage, series resistance and shunt resistances, diffusion capacitance, electric power, fill factor and the photovoltaic conversion efficiency. We determined the maximum electric power, the operating point of the solar cell and photovoltaic conversion efficiency according to the depth z in the base. We showed that the photocurrent density decreases with the depth z. The photovoltage decreased when the depth base increases. Series and shunt resistances were deduced from electrical model and were influenced and the applied the depth base. The capacity decreased with the depth z of the base. We had studied the influence of the variation of the depth z on the electrical parameters in the base.

  1. Characterization of Pseudomonas aeruginosa isolates from dogs and cats in Japan: current status of antimicrobial resistance and prevailing resistance mechanisms.

    Science.gov (United States)

    Harada, Kazuki; Arima, Sayuri; Niina, Ayaka; Kataoka, Yasushi; Takahashi, Toshio

    2012-02-01

    Seventy-three Pseudomonas aeruginosa isolates were collected from dogs and cats in Japan to investigate antimicrobial susceptibility and resistance mechanisms to anti-pseudomonal agents. Resistance rates against orbifloxacin, enrofloxacin, ciprofloxacin, cefotaxime, aztreonam and gentamicin were 34.2, 31.5, 20.5, 17.8, 12.3 and 4.1%, respectively. The degree of resistance to cefotaxime, orbifloxacin, and enrofloxacin was greatly affected by efflux pump inhibitors, indicating overexpression of efflux pump contributes to these resistances. Notably, orbifloxacin and enrofloxacin resistance was observed even in isolates without mutations in the target sites. This is the first report on cephalosporin- and fluoroquinolone-resistant isolates of P. aeruginosa from Japanese companion animals. © 2012 The Societies and Blackwell Publishing Asia Pty Ltd.

  2. Multidrug-resistant and extensively drug-resistant tuberculosis: a review of current concepts and future challenges.

    Science.gov (United States)

    Günther, Gunar

    2014-06-01

    Multidrug-resistant and extensively drug-resistant tuberculosis are recent global health issues, which makes tuberculosis - after the success of short course treatment during the second half of the last century - a major health challenge. Globalisation, health inequalities, competing economic interests and political instability contribute substantially to the spread of drug-resistant strains, which are associated with high rates of morbidity and mortality. Issues such as increasing transmission of drug-resistant strains, poor diagnostic coverage and a lengthy, toxic treatment need to be overcome by innovative approaches to tuberculosis control, prevention, diagnostics and treatment. This review addresses recent developments and future concepts. © 2014 Royal College of Physicians.

  3. Determination of over current protection thresholds for class D audio amplifiers

    DEFF Research Database (Denmark)

    Nyboe, Flemming; Risbo, L; Andreani, Pietro

    2005-01-01

    Monolithic class-D audio amplifiers typically feature built-in over current protection circuitry that shuts down the amplifier in case of a short circuit on the output speaker terminals. To minimize cost, the threshold at which the device shuts down must be set just above the maximum current...

  4. Alternating current electrical stimulation enhanced chemotherapy: a novel strategy to bypass multidrug resistance in tumor cells

    International Nuclear Information System (INIS)

    Janigro, Damir; Perju, Catalin; Fazio, Vincent; Hallene, Kerri; Dini, Gabriele; Agarwal, Mukesh K; Cucullo, Luca

    2006-01-01

    Tumor burden can be pharmacologically controlled by inhibiting cell division and by direct, specific toxicity to the cancerous tissue. Unfortunately, tumors often develop intrinsic pharmacoresistance mediated by specialized drug extrusion mechanisms such as P-glycoprotein. As a consequence, malignant cells may become insensitive to various anti-cancer drugs. Recent studies have shown that low intensity very low frequency electrical stimulation by alternating current (AC) reduces the proliferation of different tumor cell lines by a mechanism affecting potassium channels while at intermediate frequencies interfere with cytoskeletal mechanisms of cell division. The aim of the present study is to test the hypothesis that permeability of several MDR1 over-expressing tumor cell lines to the chemotherapic agent doxorubicin is enhanced by low frequency, low intensity AC stimulation. We grew human and rodent cells (C6, HT-1080, H-1299, SKOV-3 and PC-3) which over-expressed MDR1 in 24-well Petri dishes equipped with an array of stainless steel electrodes connected to a computer via a programmable I/O board. We used a dedicated program to generate and monitor the electrical stimulation protocol. Parallel cultures were exposed for 3 hours to increasing concentrations (1, 2, 4, and 8 μM) of doxorubicin following stimulation to 50 Hz AC (7.5 μA) or MDR1 inhibitor XR9576. Cell viability was assessed by determination of adenylate kinase (AK) release. The relationship between MDR1 expression and the intracellular accumulation of doxorubicin as well as the cellular distribution of MDR1 was investigated by computerized image analysis immunohistochemistry and Western blot techniques. By the use of a variety of tumor cell lines, we show that low frequency, low intensity AC stimulation enhances chemotherapeutic efficacy. This effect was due to an altered expression of intrinsic cellular drug resistance mechanisms. Immunohistochemical, Western blot and fluorescence analysis revealed

  5. Coil in coil - components for the high voltage superconducting resistive current limiter CULT 110

    Science.gov (United States)

    Elschner, S.; Stemmle, M.; Breuer, F.; Walter, H.; Frohne, C.; Noe, M.; Bock, J.

    2008-02-01

    The German government (BMBF/VDI) funded project CULT 110 is presently the largest European current limiter project and aims at the development of a one-phase resistive limiter for the voltage level of 110 kV. The contribution presents the actual state of development of the superconducting components. As in the successful predecessor project CURL 10 these are made of melt cast processed BSCCO 2212 bulk material, however monofilar instead of bifilar coils are used. The electrical protection concept is based on a normal conducting coil arranged around a superconducting coil and connected in parallel. Simultaneously this coil serves as an electrical bypass and, under fault conditions, generates a magnetic field for quench homogenisation. Since no continuously connected shunt is needed, a much higher voltage during faults can be applied. The rules for an optimum superconductor and coil design are given and the viability of the whole concept is demonstrated by both, experiment and numerical simulation.

  6. Double functions of porous TiO2 electrodes on CH3NH3PbI3 perovskite solar cells: Enhancement of perovskite crystal transformation and prohibition of short circuiting

    Science.gov (United States)

    Murugadoss, Govindhasamy; Mizuta, Gai; Tanaka, Soichiro; Nishino, Hitoshi; Umeyama, Tomokazu; Imahori, Hiroshi; Ito, Seigo

    2014-08-01

    In order to analyze the crystal transformation from hexagonal PbI2 to CH3NH3PbI3 by the sequential (two-step) deposition process, perovskite CH3NH3PbI3 layers were deposited on flat and/or porous TiO2 layers. Although the narrower pores using small nanoparticles prohibited the effective transformation, the porous-TiO2 matrix was able to help the crystal transformation of PbI2 to CH3NH3PbI3 by sequential two-step deposition. The resulting PbI2 crystals in porous TiO2 electrodes did not deteriorate the photovoltaic effects. Moreover, it is confirmed that the porous TiO2 electrode had served the function of prohibiting short circuits between working and counter electrodes in perovskite solar cells.

  7. Double functions of porous TiO2 electrodes on CH3NH3PbI3 perovskite solar cells: Enhancement of perovskite crystal transformation and prohibition of short circuiting

    Directory of Open Access Journals (Sweden)

    Govindhasamy Murugadoss

    2014-08-01

    Full Text Available In order to analyze the crystal transformation from hexagonal PbI2 to CH3NH3PbI3 by the sequential (two-step deposition process, perovskite CH3NH3PbI3 layers were deposited on flat and/or porous TiO2 layers. Although the narrower pores using small nanoparticles prohibited the effective transformation, the porous-TiO2 matrix was able to help the crystal transformation of PbI2 to CH3NH3PbI3 by sequential two-step deposition. The resulting PbI2 crystals in porous TiO2 electrodes did not deteriorate the photovoltaic effects. Moreover, it is confirmed that the porous TiO2 electrode had served the function of prohibiting short circuits between working and counter electrodes in perovskite solar cells.

  8. Mapping geological structures in bedrock via large-scale direct current resistivity and time-domain induced polarization tomography

    DEFF Research Database (Denmark)

    Rossi, Matteo; Olsson, Per-Ivar; Johansson, Sara

    2017-01-01

    An investigation of geological conditions is always a key point for planning infrastructure constructions. Bedrock surface and rock quality must be estimated carefully in the designing process of infrastructures. A large direct-current resistivity and time-domain induced-polarization survey has......, there are northwest-trending Permian dolerite dykes that are less deformed. Four 2D direct-current resistivity and time-domain induced-polarization profiles of about 1-km length have been carefully pre-processed to retrieve time-domain induced polarization responses and inverted to obtain the direct......-current resistivity distribution of the subsoil and the phase of the complex conductivity using a constant-phase angle model. The joint interpretation of electrical resistivity and induced-polarization models leads to a better understanding of complex three-dimensional subsoil geometries. The results have been...

  9. Fault current contribution from VSC-based wind turbines to the grid

    DEFF Research Database (Denmark)

    Valentini, Massimo; Akhmatov, Vladislav; Iov, Florin

    2008-01-01

    current injections during the fault. In this paper an equivalent VSC-based wind turbine model for short-circuit calculations at steady-state conditions is developed and presented. The model is implemented in DigSILENT PowerFactory using the DPL-Programming Language. The developed wind turbine model...... Power. The wind turbine model is finally rescaled to obtain an aggregate wind farm model and used to perform short-circuit calculations in a realistic scenario; the Danish transmission system is considered and a large offshore wind farm with VSC-based wind turbines is included in the investigation....

  10. A Technique to Estimate the Equivalent Loss Resistance of Grid-Tied Converters for Current Control Analysis and Design

    DEFF Research Database (Denmark)

    Vidal, Ana; Yepes, Alejandro G.; Fernandez, Francisco Daniel Freijedo

    2015-01-01

    by means of an equivalent series resistance. This paper proposes a method to identify the VSC equivalent loss resistance for the proper tuning of the current control loop. It is based on analysis of the closed-loop transient response provided by a synchronous proportional-integral current controller......, according to the internal model principle. The method gives a set of loss resistance values linked to working conditions, which can be used to improve the tuning of the current controllers, either by online adaptation of the controller gains or by open-loop adaptive adjustment of them according to prestored......Rigorous analysis and design of the current control loop in voltage source converters (VSCs) requires an accurate modeling. The loop behavior can be significantly influenced by the VSC working conditions. To consider such effect, converter losses should be included in the model, which can be done...

  11. MAXIMUM STEADY VOLTAGE AND CURRENT IN A HOMOGENEOUS ALTERNATING CURRENT LINE

    Directory of Open Access Journals (Sweden)

    Patsiuk V.I

    2013-08-01

    Full Text Available The paper considers the problem of determining of maximum values of voltage and current in a long line. The processes have been analyzed at stationary processes, depending on the length of the line and its load. Line length has been varied from zero to its wave length. Range of the load value has been changed from short-circuit mode to idle mode. The method of complex amplitudes has been used for this research. Modes have been considered for the ideal line without distortion. Exact analytical solutions have been obtained for these types of circuits. Calculations have been made for lines with arbitrary losses. It has been found that for the ideal line and undistorted lines the set of the maximum voltage and current could be always achieved for degenerated modes. It has been observed that for the case of lines with arbitrary losses local maxima for current and voltage could take place (when the load on the mode of short- circuit current up to idle mode, and the physical length of the line from zero to its wave length. Introduction of dimensionless parameter of load, for short-circuit and no-load, made it possible to obtain generalized dependencies between changing of investigated parameters for any wave length of the line and the range of variation of its load.

  12. Antibiotic resistance in Mexico: a brief overview of the current status and its causes.

    Science.gov (United States)

    Amábile-Cuevas, Carlos

    2010-03-29

    As in many other developing countries, conditions that may foster antibiotic resistance in Mexico differ from developed countries, and so resistance prevalence. Fecal pollution and other traits of overcrowded, poor cities, might create ideal settings for selecting, exchanging and maintaining resistance traits. Medical abuse of antibiotics, along with low-quality drugs, are also present as in many developing countries. Self-prescription, a common yet unmeasured practice among Mexican population, may also contribute to increased resistance rates. Pneumococcal resistance towards penicillin and macrolides are the highest in Latin American countries, as is resistance of Salmonella and uropathogenic Escherichia coli towards ampicillin and sulfamethoxazole-trimethoprim; about one tenth of isolates of these gram-negative pathogens seem to produce extended-spectrum beta-lactamases (ESBL). High rates of multiple-drug resistant Mycobacterium tuberculosis are also found in Mexico, although there is no report of extensively drug-resistant strains. As to hospital-acquired pathogens, about a third of E. coli and Klebsiella isolates are ESBL-producers, and half of Staphylococcus aureus isolates are resistant to oxacillin (MRSA). Around 40% Pseudomonas aeruginosa isolates are resistant to ceftazidime, imipenem or levofloxacin. Although community-acquired MRSA, vancomycin-resistant enterococci, and other resistance problems found in developed countries, are not as common in Mexico, local issues are no small concern, and are disturbingly moving towards outpatients.

  13. Geophysical investigation of Red Devil mine using direct-current resistivity and electromagnetic induction, Red Devil, Alaska, August 2010

    Science.gov (United States)

    Burton, Bethany L.; Ball, Lyndsay B.

    2011-01-01

    Red Devil Mine, located in southwestern Alaska near the Village of Red Devil, was the state's largest producer of mercury and operated from 1933 to 1971. Throughout the lifespan of the mine, various generations of mills and retort buildings existed on both sides of Red Devil Creek, and the tailings and waste rock were deposited across the site. The mine was located on public Bureau of Land Management property, and the Bureau has begun site remediation by addressing mercury, arsenic, and antimony contamination caused by the minerals associated with the ore deposit (cinnabar, stibnite, realgar, and orpiment). In August 2010, the U.S. Geological Survey completed a geophysical survey at the site using direct-current resistivity and electromagnetic induction surface methods. Eight two-dimensional profiles and one three-dimensional grid of direct-current resistivity data as well as about 5.7 kilometers of electromagnetic induction profile data were acquired across the site. On the basis of the geophysical data and few available soil borings, there is not sufficient electrical or electromagnetic contrast to confidently distinguish between tailings, waste rock, and weathered bedrock. A water table is interpreted along the two-dimensional direct-current resistivity profiles based on correlation with monitoring well water levels and a relatively consistent decrease in resistivity typically at 2-6 meters depth. Three settling ponds used in the last few years of mine operation to capture silt and sand from a flotation ore processing technique possessed conductive values above the interpreted water level but more resistive values below the water level. The cause of the increased resistivity below the water table is unknown, but the increased resistivity may indicate that a secondary mechanism is affecting the resistivity structure under these ponds if the depth of the ponds is expected to extend below the water level. The electromagnetic induction data clearly identified the

  14. Metallurgical Effects of Shunting Current on Resistance Spot-Welded Joints of AA2219 Sheets

    Science.gov (United States)

    Jafari Vardanjani, M.; Araee, A.; Senkara, J.; Jakubowski, J.; Godek, J.

    2016-08-01

    Shunting effect is the loss of electrical current via the secondary circuit provided due to the existence of previous nugget in a series of welding spots. This phenomenon influences on metallurgical aspects of resistance spot-welded (RSW) joints in terms of quality and performance. In this paper RSW joints of AA2219 sheets with 1 mm thickness are investigated metallurgically for shunted and single spots. An electro-thermal finite element analysis is performed on the RSW process of shunted spot and temperature distribution and variation are obtained. These predictions are then compared with experimental micrographs. Three values of 5 mm, 20 mm, and infinite (i.e., single spot) are assumed for welding distance. Numerical and experimental results are matching each other in terms of nugget and HAZ geometry as increasing distance raised nugget size and symmetry of HAZ. In addition, important effect of shunting current on nugget thickness, microstructure, and Copper segregation on HAZ grain boundaries were discovered. A quantitative analysis is also performed about the influence of welding distance on important properties including ratio of nugget thickness and diameter ( r t), ratio of HAZ area on shunted and free side of nugget ( r HA), and ratio of equivalent segregated and total amount of Copper, measured in sample ( r Cu) on HAZ. Increasing distance from 5 mm to infinite, indicated a gain of 111.04, -45.55, and -75.15% in r t, r HA, and r Cu, respectively, while obtained ratios for 20 mm welding distance was suitable compared to single spot.

  15. Sheet resistivity of silicon wafers implanted with a high current machine

    International Nuclear Information System (INIS)

    Steeples, K.

    1985-01-01

    Silicon wafers, as used in the integrated circuits and semiconductor device industry, have been implanted with all the common dopants using Eaton Corporation's commercially available 'NV' series of high current implanters. Most detailed studies of the implanted wafers have focused on using arsenic and boron as dopants since the transport of these dopants in silicon has been found to be more compatible with the trend towards shrinking device dimensions. Four point probe measurements have been taken on implanted wafers with subsequent annealing to indicate the quality and effect of the implant. The variation of sheet resistance with dose and energy have been studied using a machine in standard condition over the range of 10 14 -10 16 ions/cm 2 and over an energy range of 5-180 keV for arsenic and boron implants into bare wafers and wafers with screen oxides. Dose control at low doses in the Eaton High Current Implanter has been studied over a range of 10 10 -10 13 ions/cm 2 using MOS devices and other measurements. Repeatability of the machines has been obtained by tracking the manufacture of over one hundred machines for nearly three years. With the use of an Eaton Standard Test Implant Procedure for each machine before shipment, it has been shown that the dose repeatability can be as good as 2% (including furnace and four point probe variations) for machine to machine. The repeatability within a single machine was found to be better than 0.5%. Arsenic ion beams have shown excellent independence of end station pressure, as may occur during photoresist outgassing or controlled gas leaks. Boron beams have a higher electron capture cross-section than other commonly used beams and require a dose control compensation for high end station pressure implants to give agreement with the low pressure regime. (orig./TW)

  16. Superconducting dc fault current limiter; Limiteur supraconducteur de courant continu

    Energy Technology Data Exchange (ETDEWEB)

    Cointe, Y

    2007-12-15

    Within the framework of the electric power market liberalization, DC networks have many interests compared to alternative ones, but their protections need to use new systems. Superconducting fault current limiters enable by an overstepping of the critical current to limit the fault current to a preset value, lower than the theoretical short-circuit current. For these applications, coated conductors offer excellent opportunities. We worked on the implementation of these materials and built a test bench. We carried out limiting experiments to estimate the quench homogeneity at various short-circuit parameters. An important point is the temperature measurement by deposited sensors on the ribbon, results are in good correlation with the theoretical models. Improved quench behaviours for temperatures close to the critical temperature have been confirmed. Our results enable to better understand the limitation mechanisms of coated conductors. (author)

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

    Science.gov (United States)

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

    2017-01-01

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

  18. Ground penetrating radar and direct current resistivity evaluation of the desiccation test cap, Savannah River Site

    International Nuclear Information System (INIS)

    Wyatt, D.E.; Cumbest, R.J.

    1996-04-01

    The Savannah River Site (SRS) has a variety of waste units that may be temporarily or permanently stabilized by closure using an impermeable cover to prevent groundwater infiltration. The placement of an engineered kaolin clay layer over a waste unit is an accepted and economical technique for providing an impermeable cover but the long term stability and integrity of the clay in non-arid conditions is unknown. A simulated kaolin cap has been constructed at the SRA adjacent to the Burial Ground Complex. The cap is designed to evaluate the effects of desiccation on clay integrity, therefore half of the cap is covered with native soil to prevent drying, while the remainder of the cap is exposed. Measurements of the continuing impermeability of a clay cap are difficult because intrusive techniques may locally compromise the structure. Point measurements made to evaluate clay integrity, such as those from grid sampling or coring and made through a soil cover, may miss cracks, joints or fissures, and may not allow for mapping of the lateral extent of elongate features. Because of these problems, a non-invasive technique is needed to map clay integrity, below a soil or vegetation cover, which is capable of moderate to rapid investigation speeds. Two non-intrusive geophysical techniques, direct current resistivity and ground penetrating radar (GPR), have been successful at the SRS in geologically mapping shallow subsurface clay layers. The applicability of each technique in detecting the clay layer in the desiccation test cap and associated anomalies was investigated

  19. A Flexible Power Control Method of VSC-HVDC Link for the Enhancement of Effective Short-Circuit Ratio in a Hybrid Multi-Infeed HVDC System

    DEFF Research Database (Denmark)

    Liu, Yan; Chen, Zhe

    2013-01-01

    With the emerging use of voltage source converter high voltage direct current (VSC-HVDC) links, the hybrid multi-infeed HVDC (HMIDC) system that includes the line commutated converter (LCC) HVDC and the VSC-HVDC links is becoming a promising power transmission structure in the modern power systems......, based on the calculation results, a flexible power control strategy for the VSC-HVDC link is developed to provide maximum reactive power support under grid faults. The theoretical analysis of the HMIDC system is based on the Danish transmission grid, evaluated through PSCAD simulations under different...... grid fault conditions. Simulation results are presented to validate the expected performance of the proposed method....

  20. CONCEPTS OF IMPROVING CURRENT PROTECTION OF POWER-GRID LINES

    Directory of Open Access Journals (Sweden)

    F. A. Romaniuk

    2015-01-01

    Full Text Available The  6–35  kV  power-grid  current  protection  serves  to  protect  the  transmission  lines against phase-to-phase short-circuits. The major disadvantage of it lies in the relatively large time delays of the last stages especially in the main sections of the grid owing to the stepped relay characteristics as well as a large number of the steps. A full-fledged protection of the 6–35 kV lines against inter-phase short circuits can be provided by the two-stage current protection: the first stage being the current cutoff without any time delay and the second stage – the maximum current protection where the time delay is linear contingent on the distance between the protection placement and the fault-point location. The article introduces the rating formulae for the time delays of the second-stage and their exemplary graphic presentation. The authors offer a variant for solving the problem with computation of the second-stage time delays in those instances where several feeders diverge from the bus bars of the substation located in the end of the protected line.Improving current protections for the 6–35 kV transmission lines with one-end power supply against interphase short-circuits can be based on the collective application of the following principles: accounting for the type and location of the short-circuit which provides for the high-performance cutoff zone instantaneous expansion and its independence on the mode of failure and the grid operation mode. It also allows increase of the last stage sensitiveness towards asymmetrical short-circuits; detection of the short-circuit location only on the results of fault currents measurement which simplifies the protection implementation; realization of the last (second protection stage with linear-dependent time delay which ensures potentiality of its operation speed increase.

  1. Current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Loescher, D.H. [Sandia National Labs., Albuquerque, NM (United States). Systems Surety Assessment Dept.; Noren, K. [Univ. of Idaho, Moscow, ID (United States). Dept. of Electrical Engineering

    1996-09-01

    The current that flows between the electrical test equipment and the nuclear explosive must be limited to safe levels during electrical tests conducted on nuclear explosives at the DOE Pantex facility. The safest way to limit the current is to use batteries that can provide only acceptably low current into a short circuit; unfortunately this is not always possible. When it is not possible, current limiters, along with other design features, are used to limit the current. Three types of current limiters, the fuse blower, the resistor limiter, and the MOSFET-pass-transistor limiters, are used extensively in Pantex test equipment. Detailed failure mode and effects analyses were conducted on these limiters. Two other types of limiters were also analyzed. It was found that there is no best type of limiter that should be used in all applications. The fuse blower has advantages when many circuits must be monitored, a low insertion voltage drop is important, and size and weight must be kept low. However, this limiter has many failure modes that can lead to the loss of over current protection. The resistor limiter is simple and inexpensive, but is normally usable only on circuits for which the nominal current is less than a few tens of milliamperes. The MOSFET limiter can be used on high current circuits, but it has a number of single point failure modes that can lead to a loss of protective action. Because bad component placement or poor wire routing can defeat any limiter, placement and routing must be designed carefully and documented thoroughly.

  2. Rf-assisted current startup in the Fusion Engineering Device (FED)

    Energy Technology Data Exchange (ETDEWEB)

    Borowski, S.K.; Peng, Y.K.M.; Kammash, T.

    1982-08-01

    Auxiliary rf heating of electrons before and during the current rise phase in the Fusion Engineering Device is examined as a means of reducing both the initiation loop voltage and resistive flux expenditure during startup. Prior to current initiation 1 to 2 MW of electron cyclotron resonance heating (ECRH) power at approx. 90 GHz is used to create a small volume of high conductivity plasma (T/sub e/ approx. = 100 eV, n/sub e/ approx. = 10/sup 13/ cm/sup -3/) near the upper hybrid resonance (UHR) region. This plasma conditioning permits a small radius (a/sub o/ approx. = 0.2 to 0.4 m) current channel to be established with a relatively low initial loop voltage (less than or equal to 25 V). During the subsequent plasma expansion and current ramp phase, additional rf power is introduced to reduce volt-second consumption due to plasma resistance. A near classical particle and energy transport model has been developed to estimate the efficiency of electron heating in a currentless toroidal plasma. The model assumes that preferential electron heating at the UHR leads to the formation of an ambipolar sheath potential between the neutral plasma and the conducting vacuum vessel and limiter. The ambipolar electric field (E/sub AMB/) enables the plasma to neutralize itself via poloidal E vector/sub AMB/ x B vector drift. This form of effective rotational transform short-circuits the vertical charge separation and improves particle confinement.

  3. A superconducting direct-current limiter with a power of up to 8 MVA

    Science.gov (United States)

    Fisher, L. M.; Alferov, D. F.; Akhmetgareev, M. R.; Budovskii, A. I.; Evsin, D. V.; Voloshin, I. F.; Kalinov, A. V.

    2016-12-01

    A resistive switching superconducting fault current limiter (SFCL) for DC networks with a nominal voltage of 3.5 kV and a nominal current of 2 kA was developed, produced, and tested. The SFCL has two main units—an assembly of superconducting modules and a high-speed vacuum circuit breaker. The assembly of superconducting modules consists of nine (3 × 3) parallel-series connected modules. Each module contains four parallel-connected 2G high-temperature superconducting (HTS) tapes. The results of SFCL tests in the short-circuit emulation mode with a maximum current rise rate of 1300 A/ms are presented. The SFCL is capable of limiting the current at a level of 7 kA and break it 8 ms after the current-limiting mode begins. The average temperature of HTS tapes during the current-limiting mode increases to 210 K. After the current is interrupted, the superconductivity recovery time does not exceed 1 s.

  4. Resistance temperature sensor aging degradation identification using LCSR (Loop Current Step Response) test

    International Nuclear Information System (INIS)

    Santos, Roberto Carlos dos; Goncalves, Iraci Martine Pereira

    2013-01-01

    Most critical process temperatures in nuclear power plants are measured using RTD (Resistance Temperature Detector) and thermocouples. In a PWR (Pressure Water Reactor) plant, the primary coolant temperature and feedwater temperature are measured using RTDs, and the temperature of the water that exits the reactor core is measured using thermocouples. These thermocouples are mainly used for temperature monitoring purposes and are therefore not generally subject to very stringent requirements for accuracy and response-time performance. In contrast, primary coolant RTDs typically feed the plant's control and safety systems and must, therefore, be very accurate and have good dynamic performance. The response time of RTDs and thermocouples has been characterized by a single parameter called the Plunge Time Constant. This is defined as the time it takes the sensor output to achieve 63.2 percent of its final value after a step change in temperature is impressed on its surface. This step change is typically achieved by suddenly immersing the sensor in a rotating tank of water, called Plunge Test. In nuclear reactors, however, plunge testing is inconvenient because the sensor must be removed from the reactor coolant piping and taken to a laboratory for testing. Nuclear reactor service conditions of 150 bar and 300°C are difficult to reproduce in the laboratory. Therefore, all laboratory tests are performed at much milder conditions, and the results are extrapolated to service conditions. This leads to significant errors in the measurement of sensor response times and an insitu test method called LCSR - Loop Current Step Response test was developed in the mid-1970s to measure remotely the response time of RTDs. In the LCSR method, the sensing element is heated by an electric current; the current causes Joule heating in the sensor and results in a temperature transient inside the sensor. The temperature transient in the element is recorded, and from this transient, the

  5. Effect of the surface film electric resistance on eddy current detectability of surface cracks in Alloy 600 tubes

    International Nuclear Information System (INIS)

    Saario, T.; Paine, J.P.N.

    1995-01-01

    The most widely used technique for NDE of steam generator tubing is eddy current. This technique can reliably detect cracks grown in sodium hydroxide environment only at depths greater than 50% through wall. However, cracking caused by thiosulphate solutions have been detected and sized at shallower depths. The disparity has been proposed to be caused by the different electric resistance of the crack wall surface films and corrosion products in the cracks formed in different environments. This work was undertaken to clarify the role of surface film electric resistance on the disparity found in eddy current detectability of surface cracks in alloy 600 tubes. The proposed model explaining the above mentioned disparity is the following. The detectability of tightly closed cracks by the eddy current technique depends on the electric resistance of the surface films of the crack walls. The nature and resistance of the films which form on the crack walls during operation depends on the composition of the solution inside the crack and close to the crack location. During cooling down of the steam generator, because of contraction and loss of internal pressurization, the cracks are rather tightly closed so that exchange of electrolyte and thus changes in the film properties become difficult. As a result, the surface condition prevailing at high temperature is preserved. If the environment is such that the films formed on the crack walls under operating conditions have low electric resistance, eddy current technique will fail to indicate these cracks or will underestimate the size of these cracks. However, if the electric resistance of the films is high, a tightly closed crack will resemble an open crack and will be easily indicated and correctly sized by eddy current technique

  6. Current scenario of antibiotic resistance and latest strategies to overcome it

    Directory of Open Access Journals (Sweden)

    Mohankumar J Megha

    2014-09-01

    Full Text Available Antibiotic resistance in microorganisms has become a critical health issue these days and has evolved to become a worldwide health threat. Over a decade, the resistance level of bacteria has increased many folds due to various factors, accounting to the added pressure on the environmental resistome. Infections that are resistant to these antibiotics show potentially devastating effects on public health, often affecting developing countries. This review focuses on the present scenario of antibiotic resistance and enlists some of the strategies to combat this global community threat.

  7. Control of antibiotic resistance in China must not be delayed: The current state of resistance and policy suggestions for the government, medical facilities, and patients.

    Science.gov (United States)

    Tang, Qi; Song, Peipei; Li, Jiajia; Kong, Fanlei; Sun, Long; Xu, Lingzhong

    2016-02-01

    Antibiotics are medicines used to prevent and treat bacterial infections. Antibiotic resistance occurs when bacteria change in response to the use of these medicines. Antibiotic resistance is rising to dangerously high levels in all parts of the world, leading to higher medical costs, prolonged hospital stays, and increased mortality. In the European Union alone, drug-resistant bacteria are estimated to cause 25,000 deaths and cost more than US$1.5 billion every year in healthcare expenses and productivity losses. The problems of antibiotic misuse and antibiotic resistance are quite serious in China. In 2015, results of a study by the State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences indicated that the total antibiotic usage in China in 2013 was approximately 162,000 tons, including human use (48%) and use in animals (52%). This amount accounted for about half of the antibiotic usage worldwide. The per-capita use of antibiotics in China is more than 5 times that in Europe and the United States. These data mean that China is one of the world's leading countries with serious problems in terms of antibiotic misuse and antibiotic resistance. The current article analyzes the current state and harms of antibiotic misuse and causes of antibiotic resistance in China. The Government needs to pay close attention to the issue of antibiotic resistance in China and formulate a strategy at the national level. Thus, the following suggestions are offered: i) The Chinese Government should implement policies that promote antibiotic research and development; ii) Medical facilities in China should create multidisciplinary teams (MDTs) and encourage early action by MDTs to control the spread of multi-drug-resistant bacteria (MDRB); iii) An intervention in the form of health education should target patients and accompanying family members (AFM) in China. In other words, antibiotic resistance is not a personal problem but an

  8. Thiamethoxam Resistance in the House Fly, Musca domestica L.: Current Status, Resistance Selection, Cross-Resistance Potential and Possible Biochemical Mechanisms.

    Directory of Open Access Journals (Sweden)

    Hafiz Azhar Ali Khan

    Full Text Available The house fly, Musca domestica L., is an important ectoparasite with the ability to develop resistance to insecticides used for their control. Thiamethoxam, a neonicotinoid, is a relatively new insecticide and effectively used against house flies with a few reports of resistance around the globe. To understand the status of resistance to thiamethoxam, eight adult house fly strains were evaluated under laboratory conditions. In addition, to assess the risks of resistance development, cross-resistance potential and possible biochemical mechanisms, a field strain of house flies was selected with thiamethoxam in the laboratory. The results revealed that the field strains showed varying level of resistance to thiamethoxam with resistance ratios (RR at LC50 ranged from 7.66-20.13 folds. Continuous selection of the field strain (Thia-SEL for five generations increased the RR from initial 7.66 fold to 33.59 fold. However, resistance declined significantly when the Thia-SEL strain reared for the next five generations without exposure to thiamethoxam. Compared to the laboratory susceptible reference strain (Lab-susceptible, the Thia-SEL strain showed cross-resistance to imidacloprid. Synergism tests revealed that S,S,S-tributylphosphorotrithioate (DEF and piperonyl butoxide (PBO produced synergism of thiamethoxam effects in the Thia-SEL strain (2.94 and 5.00 fold, respectively. In addition, biochemical analyses revealed that the activities of carboxylesterase (CarE and mixed function oxidase (MFO in the Thia-SEL strain were significantly higher than the Lab-susceptible strain. It seems that metabolic detoxification by CarE and MFO was a major mechanism for thiamethoxam resistance in the Thia-SEL strain of house flies. The results could be helpful in the future to develop an improved control strategy against house flies.

  9. Advantages of the synthetic technique for the conduction of short circuit tests to breakers; Ventajas de la tecnica sintetica para realizar pruebas de corto circuito a interruptores

    Energy Technology Data Exchange (ETDEWEB)

    Sibilski, Henry [Instituto Electrotecnico de Varsovia, Varsovia (Poland); Ochoa Vivanco, Ruben [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1986-12-31

    In this article the operational principle of the synthetic test is described; specifically of the current injection circuit in parallel. Its utilization in the research and development of new breaker models and its wide possibilities regarding its testing characteristics is outlined. Likewise the different tests that can be performed by means of the synthetic technique are described. Finally the importance of the synthetic tests is outlined for the development of own technology in the area of interruption equipment and emphasis is made that in industrialized countries this technique is of common practice. [Espanol] En este articulo se describe el principio de operacion de la prueba sintetica; especificamente del circuito de inyeccion de corriente en paralelo. Se destaca su utilizacion en la investigacion y desarrollo de nuevos modelos de interruptores y sus amplias posibilidades en cuanto a caracteristicas de prueba. Asimismo, se describen las diferentes pruebas que pueden realizarse mediante la tecnica sintetica. Por ultimo, se destaca la importancia de las pruebas sinteticas para el desarrollo de tecnologia propia en el area de equipos de interrupcion, y se hace notar que en paises desarrollados, esta tecnica es practica comun.

  10. A cyclic GMP-dependent calcium-activated chloride current in smooth-muscle cells from rat mesenteric resistance arteries

    DEFF Research Database (Denmark)

    Matchkov, Vladimir; Aalkjær, Christian; Nilsson, Holger

    2004-01-01

    M) in the pipette solution. The current was found to be a calcium-activated chloride current with an absolute requirement for cyclic GMP (EC50 6.4 microM). The current could be activated by the constitutively active subunit of PKG. Current activation was blocked by the protein kinase G antagonist Rp-8-Br......We have previously demonstrated the presence of a cyclic GMP (cGMP)-dependent calcium-activated inward current in vascular smooth-muscle cells, and suggested this to be of importance in synchronizing smooth-muscle contraction. Here we demonstrate the characteristics of this current. Using...... conventional patch-clamp technique, whole-cell currents were evoked in freshly isolated smooth-muscle cells from rat mesenteric resistance arteries by elevation of intracellular calcium with either 10 mM caffeine, 1 microM BAY K8644, 0.4 microM ionomycin, or by high calcium concentration (900 n...

  11. Development of Grounding Resistance Analysis Model of Rod Electrode Considering the Effect of Large-Current Characteristic for Distribution Lines

    Science.gov (United States)

    Asaoka, Yoshinobu; Motoyama, Hideki; Matsubara, Hiroji; Sugimoto, Hitoshi

    Grounding resistance is one of the important parameters in the lightning-protection design of electric power systems. The grounding resistance of electrode decreases as large currents are injected to the electrode by electric discharges in soil. This characteristic is not considered in lightning protection design. Therefore, the design level is kept on the exceeding level in actual phenomena. From viewpoint of the rational lightning protection design for the electric power systems, this characteristic should be considered in practical design. In this study, experiments were conducted using rod electrodes, and the physical phenomena of the electrical discharge in soil were considered by assuming a certain electrical discharge model in soil. Based on these results, a grounding resistance large-current characteristic analysis model that could be easily used in EMTP was developed.

  12. Lock-in detection using a cryogenic low noise current preamplifier for the readout of resistive bolometers

    International Nuclear Information System (INIS)

    Yvon, D.; Sushkov, V.; Bernard, R.; Bret, J.L.; Cahan, B.; Cloue, O.; Maillard, O.; Mazeau, B.; Passerieux, J.P.; Paul, B.; Veyssiere, C.

    2002-01-01

    We implemented a low noise current preamplifier for the readout of resistive bolometers. We tested the apparatus on thermometer resistances ranging from 10 to 500 MΩ. The use of current preamplifier overcomes constraints introduced by the readout time constant due to the thermometer resistance and the input capacitance. Using cold JFETs, this preamplifier board is shown to have very low noise: the Johnson noise of the source resistor (1 fA/Hz 1/2 ) dominated in our noise measurements. We also implemented a lock-in chain using this preamplifier. Due to fast risetime, compensation of the phase shift may be unnecessary. If implemented, no tuning is necessary when the sensor impedance changes. Transients are very short, and thus low-passing or sampling of the signal is simplified. In case of spurious noise, the modulation frequency can be chosen in a much wider frequency range, without requiring a new calibration of the apparatus

  13. Antimicrobial resistance of Enterococcus isolates in Turkey: A meta-analysis of current studies.

    Science.gov (United States)

    Kilbas, Imdat; Ciftci, Ihsan Hakki

    2018-03-01

    In this study, a meta-analysis of Enterococcus isolates collected in 2000-2015 in Turkey and their susceptibility/resistance to antibiotics, clinical indications for initial drug treatment, and identification of alternative treatments was conducted. The meta-analysis examined antibiotic susceptibility/resistance in Enterococcus spp. isolates. The study was planned and conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). Statements on antimicrobial resistance were grouped according to the antimicrobial stewardship programme (ASP). The mean resistance rates of Enterococcus faecalis to vancomycin (VAN) and linezolid (LNZ) were 1.0±2.2% and 1.9±2.6%, respectively, whereas the mean resistance rates of Enterococcus faecium to VAN and LNZ were 10.3±11.3% and 2.4±0%, respectively. This study is the first meta-analysis of the resistance of clinical Enterococcus isolates in Turkey to antimicrobial agents, which is a major problem stemming from the excessive usage of antibiotics. The development of antibiotic resistance in Turkey has changed over time. To support the practice of evidence-based medicine, more notifications about Enterococcus resistance status are needed, especially notifications following ASP rules. Copyright © 2017 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  14. Epidemiology of antifungal resistance in human pathogenic yeasts: current viewpoint and practical recommendations for management.

    Science.gov (United States)

    Farmakiotis, Dimitrios; Kontoyiannis, Dimitrios P

    2017-09-01

    In this review, we describe the epidemiology and clinical significance of resistance in Candida spp. and other non-Cryptococcus yeasts. The rise in echinocandin resistance, azole resistance and cross-resistance to two or more antifungal classes [multidrug resistance (MDR)] has been a worrisome trend, mainly in US large tertiary and oncology centres, particularly as it relates to Candida glabrata. Candida kefyr is also a concern as it can be resistant to echinocandins and polyenes, especially in patients with haematological malignancies. Lately, Candida auris has drawn a lot of attention: this uncommon Candida spp. is the first globally emerging fungal pathogen that exhibits MDR and strong potential for nosocomial transmission. Its almost simultaneous spread in four continents could be indicative of increasing selection pressures from the use of antifungal agents. Echinocandin non-susceptibility is also common among non-Candida, non-Cryptococcus yeasts. As Candida resistance patterns reflect, in part, institutional practices of antifungal administration, the benefits of antifungal stewardship protocols are increasingly recognised and endorsed in recent guidelines. Development of rapid diagnostic methods for detecting or ruling out the presence of candidaemia and antifungal resistance, as well as discovery of novel antifungals, are key priorities in medical mycology research. Copyright © 2017 Elsevier B.V. and International Society of Chemotherapy. All rights reserved.

  15. Current Status on Marine Products with Reversal Effect on Cancer Multidrug Resistance

    Directory of Open Access Journals (Sweden)

    Huiqin Guo

    2012-10-01

    Full Text Available The resistance of tumor cells to a broad range of anticancer agents continues to be a problem for the success of cancer chemotherapy. Multidrug resistance (MDR is due in part to three drug transporter proteins: ABCB1/P-glycoprotein (P-gp, ABCC1/multidrug resistance protein 1 (MRP1 and ABCG2/breast cancer resistance protein (BCRP. These transporters are part of the ATP-binding cassette (ABC superfamily, whose members function as ATP-dependent drug-efflux pumps. Their activity can be blocked by various drugs such as verapamil (calcium channel blocker and cyclosporin A (immunosuppressive agent, etc. These compounds are called MDR modulators or reversals. This review highlights several marine natural products with reversal effect on multidrug resistance in cancer, including agosterol A, ecteinascidin 743, sipholane triterpenoids, bryostatin 1, and welwitindolinones.

  16. Epidemiology of anti-tuberculosis drug resistance in a chinese population: current situation and challenges ahead

    Science.gov (United States)

    2011-01-01

    Background Drug resistance has been a cause of concern for tuberculosis (TB) control in both developed and developing countries. Careful monitoring of the patterns and trends of drug resistance should remain a priority. Methods Strains were collected from 1824 diagnosed sputum smear positive pulmonary TB patients in Jiangsu province of China and then tested for drug susceptibility against rifampicin, isoniazid, ethambutol and streptomycin. The prevalence and patterns of drug resistance in mycobacterium tuberculosis (MTB) isolates were investigated. Multiple logistic regression analysis was performed to identify the risk factors for multidrug resistant (MDR) bacterial infection. The strength of association was estimated by odds ratio (OR) and 95% confidence interval (95% CI). Results The drug susceptibility tests showed that 1077(59.05%) MTB strains were sensitive to all the four antibiotics and the other 747(40.95%) strains were resistant to at least one drug. The proportions of mono-drug resistance were 28.73% for isoniazid, 19.41% for rifampicin, 29.33% for streptomycin, and 13.98% for ethambutol, respectively. The prevalence of MDR-TB was 16.61%, which was significantly different between new cases (7.63%) and those with previous treatment history (33.07%). Geographical variation of drug resistance was observed, where the proportion of MDR-TB among new cases was higher in the central (9.50%) or north part (9.57%) than that in the south area (4.91%) of Jiangsu province. The age of patients was significantly associated with the risk of drug resistance (P control. Prevention and control of drug-resistant TB should be emphasized by the revised DOTS (direct observed therapy, short course) program through prompt case detection, routine and quality-assured drug susceptibility test for patients at high risk of resistance, programmatic treatment with both first and second-line medicines, and systematic treatment observation, with priority for high MDR-TB settings. PMID

  17. Mycoplasma genitalium infection: current treatment options, therapeutic failure, and resistance-associated mutations.

    Science.gov (United States)

    Couldwell, Deborah L; Lewis, David A

    2015-01-01

    Mycoplasma genitalium is an important cause of non-gonococcal urethritis, cervicitis, and related upper genital tract infections. The efficacy of doxycycline, used extensively to treat non-gonococcal urethritis in the past, is relatively poor for M. genitalium infection; azithromycin has been the preferred treatment for several years. Research on the efficacy of azithromycin has primarily focused on the 1 g single-dose regimen, but some studies have also evaluated higher doses and longer courses, particularly the extended 1.5 g regimen. This extended regimen is thought to be more efficacious than the 1 g single-dose regimen, although the regimens have not been directly compared in clinical trials. Azithromycin treatment failure was first reported in Australia and has subsequently been documented in several continents. Recent reports indicate an upward trend in the prevalence of macrolide-resistant M. genitalium infections (transmitted resistance), and cases of induced resistance following azithromycin therapy have also been documented. Emergence of antimicrobial-resistant M. genitalium, driven by suboptimal macrolide dosage, now threatens the continued provision of effective and convenient treatments. Advances in techniques to detect resistance mutations in DNA extracts have facilitated correlation of clinical outcomes with genotypic resistance. A strong and consistent association exists between presence of 23S rRNA gene mutations and azithromycin treatment failure. Fluoroquinolones such as moxifloxacin, gatifloxacin, and sitafloxacin remain highly active against most macrolide-resistant M. genitalium. However, the first clinical cases of moxifloxacin treatment failure, due to bacteria with coexistent macrolide-associated and fluoroquinolone-associated resistance mutations, were recently published by Australian investigators. Pristinamycin and solithromycin may be of clinical benefit for such multidrug-resistant infections. Further clinical studies are required to

  18. The current status of resistance to alpha-cypermethrin, ivermectin, and amitraz of the cattle tick (Rhipicephalus microplus) in Ecuador

    Science.gov (United States)

    Garcés-Carrera, Sandra; Vanwambeke, Sophie O.; Madder, Maxime; Benítez-Ortiz, Washington

    2017-01-01

    Rhipicephalus microplus is widely distributed in tropical and subtropical areas of the world where livestock is a principal activity with great veterinary and economic importance. In Ecuador, this hematophagous ectoparasite has been observed between 0 and 2600 masl. One of the main tick control measures is the use of acaricides, which have been indiscriminately used worldwide and in Ecuador. In this country, no studies on acaricide resistance in Rhipicephalus microplus have been published. The current study aims to characterise the level of resistance of R. microplus against three main acaricides commonly used in Ecuador i.e. amitraz, alpha-cypermethrin and ivermectin to determine the level and pattern of dose-responses for R. microplus in 12 field populations (farms). The level of acaricide resistance was evaluated using three different bioassays: adult immersion test (AIT), larval package test (LPT) and larval immersion test (LIT), as recommended by the FAO. The predictive dose-responses were analysed by binomial logistics regression of the larval survival rate (resistance). In general, we found resistance of 67% for amitraz; 50% for alpha-cypermethrin and from 25 to 42% for ivermectin in the twelve field populations analysed. Resistance levels were studied in larval and adult bioassays, respectively, which were slightly modified for this study. For larval bioassays based on corrected mortality i.e. high (above 51%), medium (21–50%) and low (11–20%) resistance, percentages less than 10% were considered as susceptible. For the adult test, two resistance levels were used i.e. high (more than 76%) and medium (51 to 75%) resistance. Percentages lower than 50% were considered as susceptible. In this context, for larval bioassays, amitraz showed 21%, 38% and 8% for high, medium and low resistance, respectively. Alpha-cypermethrin presented 8%, 4 and 38% for high, medium and low resistance, respectively. Ivermectin presented 8%, 25% and 8% for high, medium and low

  19. Direct-current resistivity profiling at the Pecos River Ecosystem Project study site near Mentone, Texas, 2006

    Science.gov (United States)

    Teeple, Andrew; McDonald, Alyson K.; Payne, Jason; Kress, Wade H.

    2009-01-01

    The U.S. Geological Survey, in cooperation with Texas A&M University AgriLife, did a surface geophysical investigation at the Pecos River Ecosystem Project study site near Mentone in West Texas intended to determine shallow (to about 14 meters below the water [river] surface) subsurface composition (lithology) in and near treated (eradicated of all saltcedar) and control (untreated) riparian zone sites during June-August 2006. Land-based direct-current resistivity profiling was applied in a 240-meter section of the riverbank at the control site, and waterborne direct-current continuous resistivity profiling (CRP) was applied along a 2.279-kilometer reach of the river adjacent to both sites to collect shallow subsurface resistivity data. Inverse modeling was used to obtain a nonunique estimate of the true subsurface resistivity from apparent resistivity calculated from the field measurements. The land-based survey showed that the sub-surface at the control site generally is of relatively low resis-tivity down to about 4 meters below the water surface. Most of the section from about 4 to 10 meters below the water surface is of relatively high resistivity. The waterborne CRP surveys convey essentially the same electrical representation of the lithology at the control site to 10 meters below the water surface; but the CRP surveys show considerably lower resistivity than the land-based survey in the subsection from about 4 to 10 meters below the water surface. The CRP surveys along the 2.279-kilometer reach of the river adjacent to both the treated and control sites show the same relatively low resistivity zone from the riverbed to about 4 meters below the water surface evident at the control site. A slightly higher resistivity zone is observed from about 4 to 14 meters below the water surface along the upstream approximately one-half of the profile than along the downstream one-half. The variations in resistivity could not be matched to variations in lithology because

  20. Multi-step resistive switching behavior of Li-doped ZnO resistance random access memory device controlled by compliance current

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Chun-Cheng [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Department of Mathematic and Physical Sciences, R.O.C. Air Force Academy, Kaohsiung 820, Taiwan (China); Tang, Jian-Fu; Su, Hsiu-Hsien [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Hong, Cheng-Shong; Huang, Chih-Yu [Department of Electronic Engineering, National Kaohsiung Normal University, Kaohsiung 802, Taiwan (China); Chu, Sheng-Yuan, E-mail: chusy@mail.ncku.edu.tw [Department of Electrical Engineering, National Cheng Kung University, Tainan 701, Taiwan (China); Center for Micro/Nano Science and Technology, National Cheng Kung University, Tainan 701, Taiwan (China)

    2016-06-28

    The multi-step resistive switching (RS) behavior of a unipolar Pt/Li{sub 0.06}Zn{sub 0.94}O/Pt resistive random access memory (RRAM) device is investigated. It is found that the RRAM device exhibits normal, 2-, 3-, and 4-step RESET behaviors under different compliance currents. The transport mechanism within the device is investigated by means of current-voltage curves, in-situ transmission electron microscopy, and electrochemical impedance spectroscopy. It is shown that the ion transport mechanism is dominated by Ohmic behavior under low electric fields and the Poole-Frenkel emission effect (normal RS behavior) or Li{sup +} ion diffusion (2-, 3-, and 4-step RESET behaviors) under high electric fields.

  1. Multi-step resistive switching behavior of Li-doped ZnO resistance random access memory device controlled by compliance current

    International Nuclear Information System (INIS)

    Lin, Chun-Cheng; Tang, Jian-Fu; Su, Hsiu-Hsien; Hong, Cheng-Shong; Huang, Chih-Yu; Chu, Sheng-Yuan

    2016-01-01

    The multi-step resistive switching (RS) behavior of a unipolar Pt/Li 0.06 Zn 0.94 O/Pt resistive random access memory (RRAM) device is investigated. It is found that the RRAM device exhibits normal, 2-, 3-, and 4-step RESET behaviors under different compliance currents. The transport mechanism within the device is investigated by means of current-voltage curves, in-situ transmission electron microscopy, and electrochemical impedance spectroscopy. It is shown that the ion transport mechanism is dominated by Ohmic behavior under low electric fields and the Poole-Frenkel emission effect (normal RS behavior) or Li + ion diffusion (2-, 3-, and 4-step RESET behaviors) under high electric fields.

  2. Effects of Combined Resistive Underwater Exercises and Interferential Current Therapy in Patients with Juvenile Idiopathic Arthritis: A Randomized Controlled Trial.

    Science.gov (United States)

    Elnaggar, Ragab K; Elshafey, Mohammed A

    2016-02-01

    The objective of this study was to verify the effects of combined resistive underwater exercises and interferential current on the peak torque of the quadriceps and hamstrings and pain levels in patients with juvenile idiopathic arthritis. This is a randomized controlled study; 30 children with polyarticular juvenile idiopathic arthritis were randomly distributed into two groups: the control group (n = 15) received the traditional physical therapy program and the study group (n = 15) received resistive underwater exercises and interferential current therapy. Peak torque of the quadriceps and hamstrings and pain levels were evaluated before treatment, 1 mo later, and after 3 mos using the HUMAC NORM, CSMI Testing and Rehabilitation Isokinetic System and visual analog scale, respectively. In the control group, all measures showed significant differences (P interferential current therapy is a potentially valuable treatment for patients with juvenile idiopathic arthritis.

  3. Mycoplasma genitalium infection: current treatment options, therapeutic failure, and resistance-associated mutations

    Directory of Open Access Journals (Sweden)

    Couldwell DL

    2015-05-01

    Full Text Available Deborah L Couldwell,1,2 David A Lewis1,21Western Sydney Sexual Health Centre, Parramatta, 2Centre for Infectious Diseases and Microbiology and Marie Bashir Institute for Infectious Diseases and Biosecurity, Westmead Clinical School, University of Sydney, Sydney, NSW, Australia Abstract: Mycoplasma genitalium is an important cause of non-gonococcal urethritis, cervicitis, and related upper genital tract infections. The efficacy of doxycycline, used extensively to treat non-gonococcal urethritis in the past, is relatively poor for M. genitalium infection; azithromycin has been the preferred treatment for several years. Research on the efficacy of azithromycin has primarily focused on the 1 g single-dose regimen, but some studies have also evaluated higher doses and longer courses, particularly the extended 1.5 g regimen. This extended regimen is thought to be more efficacious than the 1 g single-dose regimen, although the regimens have not been directly compared in clinical trials. Azithromycin treatment failure was first reported in Australia and has subsequently been documented in several continents. Recent reports indicate an upward trend in the prevalence of macrolide-resistant M. genitalium infections (transmitted resistance, and cases of induced resistance following azithromycin therapy have also been documented. Emergence of antimicrobial-resistant M. genitalium, driven by suboptimal macrolide dosage, now threatens the continued provision of effective and convenient treatments. Advances in techniques to detect resistance mutations in DNA extracts have facilitated correlation of clinical outcomes with genotypic resistance. A strong and consistent association exists between presence of 23S rRNA gene mutations and azithromycin treatment failure. Fluoroquinolones such as moxifloxacin, gatifloxacin, and sitafloxacin remain highly active against most macrolide-resistant M. genitalium. However, the first clinical cases of moxifloxacin treatment

  4. Influence of electrical current variance and thermal resistances on optimum working conditions and geometry for thermoelectric energy harvesting

    Science.gov (United States)

    Gomez, Miguel; Reid, Rachel; Ohara, Brandon; Lee, Hohyun

    2013-05-01

    Recent reports on enhanced thermoelectric figure of merits based on nanoscale effects have revived interest in potential applications of thermoelectric modules for waste heat recovery and distributed power generation. However, studies of optimized working conditions have not been thoroughly investigated. The majority of the previous studies on optimum load resistance for maximum power output or maximum efficiency assume temperatures at the ends of thermoelectric materials are known and constant. In reality, temperature should be determined by the energy conservation equations, which are functions of the load resistance, as well as the thermal resistances of the heat source, heat sink, and contact pads. This work exploits a numerical method to determine the actual temperature of thermoelectric materials, and optimum working conditions for thermoelectric energy harvesting are presented. The proposed model considers the effect of thermal resistances between a thermoelectric module and heat reservoirs, and the electrical current variation with respect to load resistance. The optimum condition for load resistance ratio was observed to occur at larger values than those obtained from traditional optimization work. Additionally, optimum geometry for a thermoelectric module is suggested for energy harvesting methods, where forced convection or oversized heat sinks cannot be used. Experimental results obtained from a commercial thermoelectric module are also presented to validate the proposed model. This work forms a basis to predict optimum working conditions in various thermoelectric energy harvesting applications.

  5. Current status of Helicobacter pylori resistance to tetracycline: a systematic review of the literature

    OpenAIRE

    Ramírez-Bulla, Paola; Grupo de Enfermedades Infecciosas. Departamento de Microbiología. Facultad de Ciencias. Pontificia Universidad Javeriana. Bogotá, D.C.; Mercado-Reyes, Marcela; Grupo de Enfermedades Infecciosas. Departamento de Microbiología. Facultad de Ciencias. Pontificia Universidad Javeriana. Bogotá, D.C.; Trespalacios-Rangel, Alba Alicia; Grupo de Enfermedades Infecciosas. Departamento de Microbiología. Facultad de Ciencias. Pontificia Universidad Javeriana. Bogotá, D.C.,; Avila-Coy, Jenny; Grupo de Enfermedades Infecciosas. Departamento de Microbiología. Facultad de Ciencias. Pontificia Universidad Javeriana. Bogotá, D.C.,; Otero-Regino, William; Unidad de Gastroenterología, Universidad Nacional de Colombia, Bogotá, D.C.

    2012-01-01

    Objective. To determine the prevalence of Helicobacter pylori resistance to and the possible mutations that generate this worldwide resistance. Materials and methods. A systematic search for literature was performed in the databases Medline, Science Direct (Elsevier), Ovid, PubMed, Lilacsand MedicLatina using relevant key words. Data extraction was independent and checklists were prepared to assess the methodologicalquality of the studies. Analysis of information was done with RevMan 5®. Resu...

  6. Aspirin Resistance and Promoting Blood Circulation and Removing Blood Stasis: Current Situation and Prospectives

    OpenAIRE

    Jie Wang; Xingjiang Xiong; Bo Feng

    2014-01-01

    Aspirin plays a crucial physiological and pathophysiological role in cardiovascular diseases and cerebrovascular diseases by irreversibly inhibiting thromboxane A2. However, some patients may be “resistant” to its effect. The resistance has close association with adverse cardiovascular outcomes and increased mortality, so that resolving the problem of aspirin resistance (AR) is widely concerned. By studying the correlation between AR and blood stasis syndrome (BSS), it is demonstrated that BS...

  7. HIV-1 drug resistance among untreated patients in India: Current status

    Directory of Open Access Journals (Sweden)

    Pachamuthu Balakrishnan

    2006-01-01

    Full Text Available HAART has dramatically improved survival and quality of life among people living with HIV and AIDS globally. However, drug resistant mutations of HIV are a great challenge to the benefits of HAART. Antiviral resistance can be mediated either by changes in the molecular target of therapy (the primary mechanism observed in HIV-1 or in other viral proteins that indirectly interfere with a drug′s activity. Drug resistant mutations easily evolve in the presence of sub-optimal adherence. With the introduction of generic HAART, there has been a steep increase in the number of patients put on HAART in India. It should also be noted that since most patients pay for medications out of their own pockets, interruptions in therapy due to monetary constraints are not uncommon. There is little information on HIV drug resistance in resource constrained settings like India where the predominant circulating HIV-1 sub-type is C. The transmissibility of drug-resistant forms of the virus is also a major concern especially when formulating treatment guidelines. This article reviews published data available on the patterns of HIV-1 drug resistance among treatment naοve in India.

  8. Current Status of Conventional and Molecular Interventions for Blast Resistance in Rice

    Directory of Open Access Journals (Sweden)

    Deepti Srivastava

    2017-11-01

    Full Text Available Pyricularia oryzae anamorph of Magnaporthe oryzae is one of the most notorious fungal pathogens causing severe economic loss in rice production worldwide. Various methods, viz. cultural, biological and molecular approaches, are utilized to counteract this pathogen. Moreover, some tolerant or resistant rice varieties have been developed with the help of breeding programmes. Isolation and molecular characterization of different blast resistance genes now open the gate for new possibilities to elucidate the actual allelic variants of these genes via various molecular breeding and transgenic approaches. However, the behavioral pattern of this fungus breakups the resistance barriers in the resistant or tolerant rice varieties. This host-pathogen barrier will be possibly countered in future research by comparative genomics data from available genome sequence data of rice and M. oryzae for durable resistance. Present review emphasized fascinating recent updates, new molecular breeding approaches, transgenic and genomics approaches (i.e. miRNA and genome editing for the management of blast disease in rice. The updated information will be helpful for the durable, resistance breeding programme in rice against blast pathogen.

  9. Don't "Short Circuit" STEM Instruction

    Science.gov (United States)

    Bruxvoort, Crystal; Jadrich, James

    2016-01-01

    Science students should undertake engineering design projects and carry out scientific investigations, as recommended by the "Next Generation Science Standards" (NGSS Lead States 2013). However, studies show that students misconstrue the goals of science and engineering and are uncertain about their respective practices (Gilbert and Wade…

  10. Current redistribution in cables made of insulated, soldered, or oxidized strands

    International Nuclear Information System (INIS)

    Turck, B.

    1979-07-01

    Current redistributions are compared in cables made of insulated strands, soldered, or oxidized strands and insulated strands with periodic joints. After discussing the different current redistributions in the cases of a rapidly changing current and a dc current, several particular situations are investigated: what happens if a strand is broken, or if a local normal zone appears that does not affect all the strands equally, the detection of this normal zone, and the influence of short circuits between strands

  11. An Improved Current Controller to ensure the robust performance of grid-connected converters under weak grid conditions

    DEFF Research Database (Denmark)

    Khazraj, Hesam; Silva, Filipe Miguel Faria da; Bak, Claus Leth

    2016-01-01

    Voltage Source Converters (VSCs) operating in very weak grids with low Short Circuit Ratio (SCR) are known to meet stability challenges. This article investigates instability of a grid connected current-controlled converter under weak grid conditions, which is often attributed to the dynamic...

  12. THE CONTROLLED CHOKE TRANSFORMER IN THE STRUCTURE OF THE ELECTROMECHANICAL SYSTEM FOR GENERATING ALTERNATING CURRENT OF FIXED FREQUENCY

    Directory of Open Access Journals (Sweden)

    S. V. Mishin

    2015-01-01

    Full Text Available This article briefly describes the design of controlled choke transformer regulator. The electrical circuit and the results of laboratory tests in the form of characteristics of idling, short circuit and performance are presented. The expediency of application of such devices in the electromechanical system of generating alternating current of constant frequency is grounded.

  13. Compliance current dependence of conversion between bipolar, unipolar, and threshold resistance switching in Mn3O4 films

    Directory of Open Access Journals (Sweden)

    Shuxiang Wu

    2015-08-01

    Full Text Available We report deterministic conversion between bipolar, unipolar and threshold resistance switching in Pt/Mn3O4/Pt memory devices via tuning compliance current. The conversion between bipolar and unipolar switching is reversible, while that between memory switching and threshold switching is irreversible. The nonvolatile bipolar resistance switching behaviors could be attributed to modification of Schottky barrier at Pt/Mn3O4 interface due to the migration of positively charged oxygen vacancies. With the increase of current, the incomplete filament formed in the set operation of bipolar switching could continue to grow and until completely form. The subsequent rupture and formation of filament consisting of oxygen vacancies under electric field are responsible for the unipolar resistance switching. Further increase of compliance current causes the volatile threshold switching behavior in the Pt/Mn3O4/Pt devices, which could be originated from formation and rupture of filament consisting of Mn ions due to the high Joule heat generated by large current.

  14. Direct current (DC) resistivity and Induced Polarization (IP) monitoring of active layer dynamics at high temporal resolution

    DEFF Research Database (Denmark)

    Doetsch, J.; Fiandaca, G.; Ingeman-Nielsen, Thomas

    2015-01-01

    With permafrost thawing and changes in active layer dynamics induced by climate change, interactions between biogeochemical and thermal processes in the ground are of great importance. Here, active layer dynamics have been monitored using direct current (DC) resistivity and induced polarization (...... non-intrusively and reliably image freezing patterns and their lateral variation on a 10-100 m scale that is difficult to sample by point measurements.......) measurements at high temporal resolution at a heath tundra site on Disko Island on the west coast of Greenland (69°N). Borehole sediment characteristics and subsurface temperatures supplemented the DC-IP measurements. Data acquired during the freezing period of October 2013 – February 2014 clearly image...... the soil freezing as a strong increase in resistivity. While the freezing horizon generally moves deeper with time, some variations in the freezing depth are observed along the profile. Comparison with depth-specific soil temperature indicates an exponential relationship between resistivity and below-freezing...

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

    Science.gov (United States)

    Colangelo, Daniele; Dutoit, Bertrand

    2012-09-01

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

  16. Current perspective on emergence, diagnosis and drug resistance in Candida auris

    Directory of Open Access Journals (Sweden)

    Sarma S

    2017-06-01

    Full Text Available Smita Sarma, Shalini Upadhyay Department of Microbiology, Medanta – The Medicity, Gurgaon, Haryana, India Abstract: Candida auris is an emerging fungus that presents a serious threat to global health. The organism is difficult to identify using conventional biochemical methods. C. auris has also attracted attention because of its reduced susceptibility to azoles, polyenes, and echinocandins, with a few strains even resistant to all three classes of antifungals. In this review paper we discuss the trends in emergence of C. auris in different parts of the world, associated risk factors, drug resistance, and diagnostic challenges. Strategies for prevention and therapeutic options for such infections is also addressed. Keywords: Candidemia, Candida haemulonii, outbreak, drug resistance

  17. Improving the leakage current of polyimide-based resistive memory by tuning the molecular chain stack of the polyimide film

    Science.gov (United States)

    Wu, Chi-Chang; Hsiao, Yu-Ping; You, Hsin-Chiang; Lin, Guan-Wei; Kao, Min-Fang; Manga, Yankuba B.; Yang, Wen-Luh

    2018-02-01

    We have developed an organic-based resistive random access memory (ReRAM) by using spin-coated polyimide (PI) as the resistive layer. In this study, the chain distance and number of chain stacks of PI molecules are investigated. We employed different solid contents of polyamic acid (PAA) to synthesize various PI films, which served as the resistive layer of ReRAM, the electrical performance of which was evaluated. By tuning the PAA solid content, the intermolecular interaction energy of the PI films is changed without altering the molecular structure. Our results show that the leakage current in the high-resistance state and the memory window of the PI-based ReRAM can be substantially improved using this technique. The superior properties of the PI-based ReRAM are ascribed to fewer molecular chain stacks in the PI films when the PAA solid content is decreased, hence suppressing the leakage current. In addition, a device retention time of more than 107 s can be achieved using this technique. Finally, the conduction mechanism in the PI-based ReRAM was analyzed using hopping and conduction models.

  18. Intern doctors’ views on the current and future antibiotic resistance situation of Chattagram Maa O Shishu Hospital Medical College, Bangladesh

    Directory of Open Access Journals (Sweden)

    Hoque R

    2015-08-01

    Full Text Available Rozina Hoque,1 Asma Mostafa,2 Mainul Haque3 1Department of Pharmacology, 2Department of Anatomy, Chattagram Maa O Shishu Hospital Medical College, Agrabad, Chittagong, Bangladesh; 3Unit of Pharmacology, Faculty of Medicine, Universiti Sultan Zainal Abidin, Terengganu, Malaysia Background: Bacterial resistance due to antibiotic misuse is reported every day. Such threat calls for a consensus to develop new strategies to prevent the development of antibiotic resistance of bacteria. Medical doctors must play a pivotal role to control and prevent the misuse of antibiotics. There were complaints that prescribers are lacking behind in updates and advancement in the field. To address such knowledge gap, a study was conducted to know the views of interns on the current antibiotic resistance situation in a teaching hospital in Bangladesh. Methods: This study was a cross-sectional, randomized, and questionnaire-based survey. Interns of the medicine, gynecology, and surgery departments of Chattagram Maa O Shishu Hospital Medical College were the study population. Results: Out of 50 respondents, 98% would like more education on antibiotic selection. All respondents believed that prescribing inappropriate or unnecessary antibiotics was professionally unethical. Ninety percent of the participants were confident in making an accurate diagnosis of infection. Eighty-four percent of them were confident about dosage schedule. In all, 98% participants thought that antibiotic resistance is a national problem and 64% of the respondents thought that same problem also existed in their hospital. Study participants were of the view that 41%–60% of antibiotic usages are irrational in Bangladesh. Fifty-eight percent of the study population thought that antimicrobial resistance (AR would be a greater problem in the future. Conclusion: The interns believe that there is a knowledge gap on AR. More emphasis should be given to AR and its implications in the undergraduate

  19. Mapping geological structures in bedrock via large-scale direct current resistivity and time-domain induced polarization tomography

    DEFF Research Database (Denmark)

    Rossi, Matteo; Olsson, Per-Ivar; Johansson, Sara

    2017-01-01

    An investigation of geological conditions is always a key point for planning infrastructure constructions. Bedrock surface and rock quality must be estimated carefully in the designing process of infrastructures. A large direct-current resistivity and time-domain induced-polarization survey has b...... been performed in Dalby, Lund Municipality, southern Sweden, with the aim of mapping lithological variations in bedrock. The geology at the site is characterised by Precambrian granitic gneisses and amphibolites, which are intensely deformed, fractured, and partly weathered. In addition......-polarization profiles. The direct-current resistivity and time-domain induced-polarization methodology proved to be a suitable technique for extensively mapping weathered zones with poor geotechnical characteristics and tectonic structures, which can lead to severe problems for infrastructure construction and....../or constitute risk zones for aquifer contamination....

  20. Current and emerging treatment options for castration-resistant prostate cancer: a focus on immunotherapy

    NARCIS (Netherlands)

    Gerritsen, W.R.; Sharma, P.

    2012-01-01

    BACKGROUND: Castration-resistant prostate cancer is a disease with limited treatment options. However, the ongoing elucidation of the mechanisms underlying this disease continues to support the development of not only novel agents, but also innovative approaches. Among these therapies, immunotherapy

  1. Current and Emerging Topical Antibacterials and Antiseptics: Agents, Action, and Resistance Patterns.

    Science.gov (United States)

    Williamson, Deborah A; Carter, Glen P; Howden, Benjamin P

    2017-07-01

    Bacterial skin infections represent some of the most common infectious diseases globally. Prevention and treatment of skin infections can involve application of a topical antimicrobial, which may be an antibiotic (such as mupirocin or fusidic acid) or an antiseptic (such as chlorhexidine or alcohol). However, there is limited evidence to support the widespread prophylactic or therapeutic use of topical agents. Challenges involved in the use of topical antimicrobials include increasing rates of bacterial resistance, local hypersensitivity reactions (particularly to older agents, such as bacitracin), and concerns about the indiscriminate use of antiseptics potentially coselecting for antibiotic resistance. We review the evidence for the major clinical uses of topical antibiotics and antiseptics. In addition, we review the mechanisms of action of common topical agents and define the clinical and molecular epidemiology of antimicrobial resistance in these agents. Moreover, we review the potential use of newer and emerging agents, such as retapamulin and ebselen, and discuss the role of antiseptic agents in preventing bacterial skin infections. A comprehensive understanding of the clinical efficacy and drivers of resistance to topical agents will inform the optimal use of these agents to preserve their activity in the future. Copyright © 2017 American Society for Microbiology.

  2. Arc Current, Voltage, and Resistance in a High Energy, Gas Filled Spark Gap

    Science.gov (United States)

    1985-06-01

    Rompe [8] show discrepancies of up to a factor of 10, excellent agreement is found with the model of Mesyats [ 6] and Vlastos [9] for times up to...Leipzig Johann Ambrosius [9] Vlastos , A.E. "The Channel Resistance of Sparks," lEE Gas Discharges Conference Proceedings, pp. 31- 34 (Sept. 1970

  3. Study of Proper Time Range for Current Flow to Resistance Spot Welding Inspected by Mechanical Property and Metallurgy Testing

    International Nuclear Information System (INIS)

    Pearsura, Prachya

    2007-08-01

    Full text: This research used the mechanical property and metallurgy testing to identify the proper time range for current flow. The specimen tested was 1 mm thick mild steel. The welded specimens were tested by Tensile Shear testing following JIS Z 3136: 1999 and Macro Structure testing follow by JIS Z 3139: 1978. Subsequently, the results from analyzing were compared with standard JIS Z 3140. The results show that the suitable current flow is 8 to 10 cycles. This technique can be applied to monitor the process and the quality of resistance spot welding

  4. Methicillin-resistant Staphylococcus aureus colonization and infection risks from companion animals: current perspectives

    Directory of Open Access Journals (Sweden)

    Petinaki E

    2015-11-01

    Full Text Available Efthimia Petinaki,1 Iris Spiliopoulou21Department of Microbiology, School of Medicine, University of Thessalia, Larissa, 2Department of Microbiology, School of Medicine, University of Patras, Patras, GreeceAbstract: Methicillin-resistant Staphylococcus aureus (MRSA remains one of the most virulent human pathogens and has also recently been recognized as such in the veterinary settings. Companion animals, including dogs, cats, horses, small exotic animals, wildlife animals, and livestock, may constitute a reservoir for MRSA transmission to humans and vice versa. The evolution, emergence, and risk factors for MRSA transmission among colonized or infected animals are reviewed in the present paper, and infection control practices are discussed.Keywords: methicillin-resistant Staphylococcus aureus, companion animals, close contacts

  5. Methicillin-resistant Staphylococcus aureus colonization and infection risks from companion animals: current perspectives

    OpenAIRE

    Petinaki E; Spiliopoulou I

    2015-01-01

    Efthimia Petinaki,1 Iris Spiliopoulou21Department of Microbiology, School of Medicine, University of Thessalia, Larissa, 2Department of Microbiology, School of Medicine, University of Patras, Patras, GreeceAbstract: Methicillin-resistant Staphylococcus aureus (MRSA) remains one of the most virulent human pathogens and has also recently been recognized as such in the veterinary settings. Companion animals, including dogs, cats, horses, small exotic animals, wildlife animals, and livestock, may...

  6. Current scenario

    Indian Academy of Sciences (India)

    First page Back Continue Last page Overview Graphics. Current scenario. India , like other parts of the world, is also facing the problem of increase in the incidence of drug resistance in tuberculosis. Multi-drug resistance (MDR, resistance to RIF & INH) and extensively drug resistant strains (X-DR, resistance to RIF, INH, FQs ...

  7. Fragmentation of the Current Sheet, Anomalous Resistivity, and Acceleration of Particles

    Czech Academy of Sciences Publication Activity Database

    Karlický, Marian; Bárta, Miroslav

    2008-01-01

    Roč. 247, č. 2 (2008), s. 335-342 ISSN 0038-0938 R&D Projects: GA AV ČR IAA300030701 Institutional research plan: CEZ:AV0Z10030501 Keywords : electric currents and current sheets * acceleration Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.774, year: 2008

  8. Primary Droop Current-Sharing Control of the Parallel DC/DC Converters System considering Output Cable Resistance

    Directory of Open Access Journals (Sweden)

    J. B. Wang

    2011-01-01

    Full Text Available This paper presents a primary droop current-sharing controller that can integrate into voltage feedback controller and, thus, provides a low-cost and simple solution for parallel DC/DC converters system. From the equivalent small-signal model, a two-port network was adapted to describe the output and control variables for designing voltage and droop current-sharing loops. From the analysis results, the designed primary droop current-sharing controller will not affect the original voltage loop gain profile to let the DC/DC converter preserve desire control performance. After designing a stable DC/DC converter with primary droop current-sharing control, the stability of the interconnected parallel DC/DC converters system was studied. When the cable resistance is reduced, when the cable resistance is reduced, the interconnected system might be unstable. Finally, some simulation and experimental results demonstrated the effectiveness of the proposed controller in a prototype parallel DC/DC converters system.

  9. CURRENT STATE OF RESISTANCE TO ANTIBIOTICS OF LAST-RESORT IN SOUTH AFRICA: A REVIEW FROM A PUBLIC HEALTH PERSPECTIVE

    Directory of Open Access Journals (Sweden)

    JOHN OSEI SEKYERE

    2016-09-01

    Full Text Available A review of the literature was undertaken to delineate the current level and mechanisms of resistance to carbapenems, colistin and tigecycline in South Africa. Thirty-two English publications and 32 National Institute of Communicable Diseases (NICD communiqués identified between early January 2000 and 20th May, 2016 showed substantial reports of NDM (n=860, OXA-48 (n=584, VIM (n=131 and IMP (n=45 carbapenemases within this period, mainly in Klebsiella pneumoniae (n=1138, Acinetobacter baumannii (n=332, Enterobacter cloacae (n=201 and Serratia marcescens (n=108. Colistin and tigecycline resistance was prevalent among K. pneumoniae, A. baumannii, S. marcescens and E. cloacae. The first mcr-1 colistin resistance gene to be detected in South Africa was reported in E. coli from livestock as well as from hospitalized and out patients. There are increasing reports of NDM and OXA-48 carbapenemases among Enterobacteriaceae and A. baumannii in South Africa. Mcr-1 is now present in South African patients and livestock. Resistance to carbapenems, colistin and tigecycline restricts infection management options for clinicians.

  10. Current State of Resistance to Antibiotics of Last-Resort in South Africa: A Review from a Public Health Perspective.

    Science.gov (United States)

    Osei Sekyere, John

    2016-01-01

    A review of the literature was undertaken to delineate the current level and mechanisms of resistance to carbapenems, colistin, and tigecycline in South Africa. Thirty-two English publications and 32 National Institute of Communicable Diseases communiqués identified between early January 2000 and 20 May, 2016 showed substantial reports of NDM ( n  = 860), OXA-48 ( n  = 584), VIM ( n  = 131), and IMP ( n  = 45) carbapenemases within this period, mainly in Klebsiella pneumoniae ( n  = 1138), Acinetobacter baumannii ( n  = 332), Enterobacter cloacae ( n  = 201), and Serratia marcescens ( n  = 108). Colistin and tigecycline resistance was prevalent among K. pneumoniae, A. baumannii, S. marcescens , and E. cloacae . The first mcr-1 colistin resistance gene to be detected in South Africa was reported in Escherichia coli from livestock as well as from hospitalized and outpatients. There are increasing reports of NDM and OXA-48 carbapenemases among Enterobacteriaceae and A. baumannii in South Africa. Mcr-1 is now present in South African patients and livestock. Resistance to carbapenems, colistin, and tigecycline restricts infection management options for clinicians.

  11. Role of Combination Antimicrobial Therapy for Vancomycin-Resistant Enterococcus faecium Infections: Review of the Current Evidence.

    Science.gov (United States)

    Yim, Juwon; Smith, Jordan R; Rybak, Michael J

    2017-05-01

    Enterococcus species are the second most common cause of nosocomial infections in the United States and are particularly concerning in critically ill patients with preexisting comorbid conditions. Rising resistance to antimicrobials that were historically used as front-line agents for treatment of enterococcal infections, such as ampicillin, vancomycin, and aminoglycosides, further complicates the treatment of these infections. Of particular concern are Enterococcus faecium strains that are associated with the highest rate of vancomycin resistance. The introduction of antimicrobial agents with specific activity against vancomycin-resistant Enterococcus (VRE) faecium including daptomycin, linezolid, quinupristin-dalfopristin, and tigecycline did not completely resolve this clinical dilemma. In this review, the mechanisms of action and resistance to currently available anti-VRE antimicrobial agents including newer agents such as oritavancin and dalbavancin will be presented. In addition, novel combination therapies including β-lactams and fosfomycin, and the promising results from in vitro, animal studies, and clinical experience in the treatment of VRE faecium will be discussed. © 2017 Pharmacotherapy Publications, Inc.

  12. Pilot study using transcutaneous electrical stimulation (interferential current) to treat chronic treatment-resistant constipation and soiling in children.

    Science.gov (United States)

    Chase, Janet; Robertson, Val J; Southwell, Bridget; Hutson, John; Gibb, Susie

    2005-07-01

    Chronic constipation in children may have organic or behavioral causes. The purpose of the present study was to investigate the effect of treatment with transcutaneous electrical stimulation (using interferential current) in children with chronic treatment-resistant constipation with proven organic disorders. Eight children (7-16 years) with at least 4 years of chronic treatment-resistant constipation and soiling, who had failed diet, laxative treatment and behavioral therapy were given 1 month of transcutaneous electrical stimulation. The three most severe cases had appendicostomies with antegrade washouts every 2-3 days to prevent impaction and reduce their soiling. Children and carers kept a daily diary of bowel habits, recording number of spontaneous defecations, episodes of soiling, use of bowel washouts and medications. Transcutaneous stimulation using interferential current was applied three times per week for 3-4 weeks using four surface electrodes, two to the paraspinal area of T9-10 to L2 and one to either side of the anterior abdominal wall beneath the costal margin. Diaries were recorded for 1 month before, during, and after stimulation and for 2 weeks 3 months later. Transcutaneous electrical stimulation using interferential current stopped soiling in 7/8 children and increased the frequency of spontaneous defecations in 5/8. Defecations remained high and soiling low for 3 months in 3/6 children (with data). These results suggest that transcutaneous electrical stimulation using interferential current has a beneficial effect for children with chronic treatment-resistant constipation. Further trials using larger series of patients are needed to confirm this benefit, to determine the ideal stimulation parameters and to investigate why electrical stimulation might be effective. (c) 2005 Blackwell Publishing Asia Pty Ltd.

  13. Critical current density versus normal-state resistivity in granular high-temperature superconductors with different average grain size

    International Nuclear Information System (INIS)

    Curras, S.R.; Veira, J.A.; Maza, J.; Vidal, Felix

    2000-01-01

    The resistivity, ρ, and the critical current density at zero applied magnetic field, J c , of ceramic Y 1 Ba 2 Cu 3 O 7-δ samples with different average grain size, a (from 5 to 14 μm), are reported. These results show that at a given temperature J c depends only on the specific contact resistance of the average grain boundary junction, ρ□, so that the product J c ρ□ is sample independent. The relevance of ρ□ and not of a on J c has been further tested on a subset of samples having very different average grain size but similar ρ□ for which negligible variations of J c are observed. (author)

  14. Safety of antimicrobial treatment during pregnancy: a current review of resistance, immunomodulation and teratogenicity.

    Science.gov (United States)

    Lamont, Harriet F; Blogg, Henrietta J; Lamont, Ronald F

    2014-12-01

    The extent of antibiotic use in pregnancy remains unknown but may occur in > 40% of pregnant women for various indications, at different gestational ages from different sources. Antibiotic resistance, alterations to the neonatal immune system causing allergy, asthma and atopic disease in later life and teratogenicity. Although teratogenesis is not a major concern, it is important, and ignorance and complacency cast a long shadow. Robust evidence exists to guide clinicians in their choice of a safe agent with respect to teratogenicity. Antibiotic resistance is a major safety concern, and together with decreased research and development of new antibiotic agents, it has required legal initiatives to encourage Big Pharma to search for safe alternatives. New information from culture-independent, molecular-based techniques has resulted in a greater understanding of the adverse effects of antepartum/intrapartum antibiotics on the maternal vaginal microbiome and the neonatal gut microbiome. As this might adversely affect the development of the immature immune system and lead to asthma, allergy and atopic disease in later life, new research merits support in scrutinizing the safety of antibiotic use in pregnancy.

  15. The promise of ketamine for treatment-resistant depression: current evidence and future directions

    Science.gov (United States)

    DeWilde, Kaitlin E.; Levitch, Cara F.; Murrough, James W.; Mathew, Sanjay J.; Iosifescu, Dan V.

    2014-01-01

    Major depressive disorder (MDD) is one of the most disabling diseases worldwide and is a significant public health threat. Current treatments for MDD primarily consist of monoamine-targeting agents and have limited efficacy. However, the glutamate neurotransmitter system has recently come into focus as a promising alternative for novel antidepressant treatments. We review the current data on the glutamate NMDA receptor antagonist ketamine, which has been shown in clinical trials to act as a rapid antidepressant in MDD. We also examine ketamine efficacy on dimensions of psychopathology, including anhedonia, cognition, and suicidality, consistent with the NIMH Research Domain Criteria (RDoC) initiative. Other aspects of ketamine reviewed in this paper include safety and efficacy, different administration methods, and the risks of misuse of ketamine outside of medical settings. Finally, we conclude with a discussion of other glutamatergic agents other than ketamine currently being tested as novel antidepressants. PMID:25649308

  16. Resistive states created in superconducting NbTiN filaments by an electrical current pulse

    Directory of Open Access Journals (Sweden)

    K. Harrabi

    2015-03-01

    Full Text Available We have observed as a function of the time the appearance of the voltage caused by a larger-than-critical (I > Ic step-pulse of current in narrow NbTiN strips at 4.2 K. Different current intensities produced either phase-slip centres characterized by a voltage saturating with the time, or ever expanding hot spots. These dissipative structures occur after a measurable delay time, whose dependence upon the ratio I/Ic can be analysed through a Ginzburg-Landau theory to yield a unique adjustable time constant.

  17. Renal Denervation for Treating Resistant Hypertension: Current Evidence and Future Insights from a Global Perspective

    Directory of Open Access Journals (Sweden)

    Y. Castro Torres

    2013-01-01

    Full Text Available Adequate blood pressure control represents an important goal for all physicians due to the complications of hypertension which reduce patients' quality of life. A new interventional strategy to reduce blood pressure has been developed for patients with resistant hypertension. Catheter-based renal denervation has demonstrated excellent results in recent investigations associated with few side effects. With the growing diffusion of this technique worldwide, some medical societies have published consensus statements to guide physicians how to best apply this procedure. Questions remain to be answered such as the long-term durability of renal denervation, the efficacy in patients with other sympathetically mediated diseases, and whether renal denervation would benefit patients with stage 1 hypertension.

  18. Influence of welding current in resistance spot welding on the properties of Zn coated steel DX51D

    OpenAIRE

    Luboš Kaščák; Ján Viňáš; Rudolf Mišičko

    2016-01-01

    The paper deals with the resistance spot welding of three galvanized car body sheets DX51D + Z - EN 10142/2000. The quality of welded joints was evaluated by destructive tests and non-destructive tests. For evaluation of joints quality the shear tension test on spot joints according to DIN 50 124 standard was used. The influence of welding parameters on the structure of a welded joint was observed by metallographic analysis. Influence of welding current from 6.0 to 7.7 kA and infl...

  19. Direct current (DC) resistivity and induced polarization (IP) monitoring of active layer dynamics at high temporal resolution

    DEFF Research Database (Denmark)

    Doetsch, Joseph; Ingeman-Nielsen, Thomas; Christiansen, Anders V.

    2015-01-01

    With permafrost thawing and changes in active layer dynamics induced by climate change, interactions between biogeochemical and thermal processes in the ground are of great importance. Here, active layer dynamics have been monitored using direct current (DC) resistivity and induced polarization (IP...... and subsurface temperatures supplemented the DC-IP measurements. A time-lapse DC-IP monitoring system has been acquiring at least six datasets per day on a 42-electrode profile with 0.5. m electrode spacing since July 2013. Remote control of the data acquisition system enables interactive adaptation...

  20. High-resolution imaging with two-axis orthogonal magneto-resistive sensor based eddy current probe

    Science.gov (United States)

    Wincheski, Buzz; Simpson, John; Seebo, Jeffery P.; Powell, Jessica

    2012-05-01

    A two-channel magneto-resistive sensor with an embedded, single-strand eddy current inducer has been fabricated and tested for applications including sensory material characterization and the analysis of intermittent contact along compression boundaries and fatigue cracks. A rapid scanning technique has also been implemented to enable high-resolution imaging of relatively large areas in modest times. Applications of the probe for high-resolution imaging of calibration artifacts and sensory materials are presented. Finite element modeling of the probe is also presented and compared with experimental measurements with good agreement.

  1. Analysis on current limiting characteristics of a transformer type SFCL with two triggering current levels

    International Nuclear Information System (INIS)

    Lim, Sung-Hun; Ko, Seckcheol; Han, Tae-Hee

    2013-01-01

    Highlights: ► We suggested the transformer type SFCL with two triggering current levels. ► The short-circuit tests for the suggested SFCL was executed. ► The fault angle as the fault conditions to verify its operation was selected. ► The usefulness of the suggested SFCL was confirmed through the short-circuit test. -- Abstract: In this paper, the transformer type superconducting fault current limiter (SFCL) with two triggering current levels was suggested and its current limiting characteristics were analyzed. The structure of the suggested transformer type SFCL with two triggering current levels largely consists of two parts. One is the transformer with two magnetically coupled coils, which correspond to the primary winding and the secondary one connected with one high-T C superconducting (HTSC) element. The other is third coil, or, another secondary winding with one HTSC element, which is wound on the same iron core together with two coils. This suggested transformer type SFCL can limit the fault current by generating its limiting impedance with two different amplitudes, which are dependent on the initial amplitude of the fault current in case of the fault occurrence. To confirm the usefulness of the proposed SFCL, the current limiting tests of the SFCL according to the fault angle, one of the effective fault conditions to affect the amplitude of the initial fault current, were carried out and its effective limiting operations were discussed

  2. Effect of Weld Current on the Microstructure and Mechanical Properties of a Resistance Spot-Welded TWIP Steel Sheet

    Directory of Open Access Journals (Sweden)

    Mumin Tutar

    2017-11-01

    Full Text Available In this study the effect of the weld current on the microstructure and mechanical properties of a resistance spot-welded twinning-induced plasticity (TWIP steel sheet was investigated using optical microscopy, scanning electron microscopy–electron back-scattered diffraction (SEM–EBSD, microhardness measurements, a tensile shear test and fractography. Higher weld currents promoted the formation of a macro expulsion cavity in the fusion zone. Additionally, higher weld currents led to a higher indentation depth, a wider heat-affected zone (HAZ, coarser grain structure and thicker annealing twins in the HAZ, and a relatively equiaxed dendritic structure in the centre of the fusion zone. The hardness values in the weld zone were lower than that of the base metal. The lowest hardness values were observed in the HAZ. No strong relationship was observed between the hardness values in the weld zone and the weld current. A higher joint strength, tensile deformation and failure energy absorption capacity were obtained with a weld current of 12 kA, a welding time of 300 ms and an electrode force of 3 kN. A complex fracture surface with both brittle and limited ductile manner was observed in the joints, while the base metal exhibited a ductile fracture. Joints with a higher tensile shear load (TSL commonly exhibited more brittle fracture characteristics.

  3. Vortex domain structures and dc current dependence of magneto-resistances in magnetic tunnel junctions

    Science.gov (United States)

    Wei, Hong-Xiang; Lu, Qing-Feng; Zhao, Su-Fen; Zhang, Xie-Qun; Feng, Jia-Feng; Han, Xiu-Feng

    2004-09-01

    Microfabrication and the magneto-transport characteristics of the magnetic tunnel junctions (MTJs) with a spin-valve-type structure of Ta (5nm)/Ni79Fe21 (25nm)/Ir22Mn78 (12nm)/Co75Fe25 (4nm)/Al(0.8nm) oxide/Co75Fe25 (4nm)/Ni79Fe21 (20nm)/Ta(5nm) were investigated in this paper. A series of experimental data measured with a MTJ was used to verify a magnon-assisted tunnelling model and theory. Furthermore, a micromagnetics simulation shows that the butterfly-like vortex domain structures can be formed under a current-induced Oersted field, which decreases the net magnetization values of the ferromagnetic electrodes under a large dc current (i.e., in high voltage regimes). It is one of the main reasons for the tunnel magnetoresistance ratios to decrease significantly at high voltage biasing.

  4. Efficacy of Transcranial Direct Current Stimulation in the Treatment: Resistant Patients who Suffer from Severe Obsessive-compulsive Disorder.

    Science.gov (United States)

    Najafi, Kiomars; Fakour, Youssef; Zarrabi, Homa; Heidarzadeh, Abtin; Khalkhali, Mohammadrasoul; Yeganeh, Taiebeh; Farahi, Hasan; Rostamkhani, Marziyeh; Najafi, Tahereh; Shabafroz, Soheil; Pakdaman, Mahdiyeh

    2017-01-01

    During the past years, significant efforts have been made to explain the biological backgrounds of obsessive-compulsive disorder (OCD). Cortical-subcortical and neurotransmitter models are used for explaining the symptoms of OCD, so our hypothesis is that brain's transcranial direct current stimulation (TDCS) can regulate the brain activities of the OCD patients. Thus, based on the mentioned issues, this research seeks to investigate the efficacy of TDCS in treatment-resistant patients who suffer from severe OCD. The present study is a clinical trial research which was based on the available sampling method, 42 treatment-resistant patients who suffer from severe OCD were selected as research's samples (2015-2016). Medical intervention protocol in this study is TDCS cathode type that was done in 15 sessions for 3 consecutive weeks (each session was conducted for 30 min daily). Yale-Brown Obsessive-Compulsive Scale was used for evaluating the efficacy of TDCS method during the 1 st , 5 th , 10 th , and 15 th sessions and it was also used for checking the 1 st and 3 rd monthly follow-up phases. Variance within-group analysis (repeated measure) showed that the mean differences in the different stages of evaluation are significant (seven stages of evaluation). TDCS can be introduced as an appropriate, strong tool for regulating the brain - behavioral systems and it can also be introduced as a suitable alternative treatment for treatment-resistant patients who suffer from severe OCD.

  5. The use of low resistivity substrates for optimal noise reduction, ground referencing, and current conduction in mixed signal ASICs

    Energy Technology Data Exchange (ETDEWEB)

    Zimmerman, T.

    1997-12-01

    This paper is distilled from a talk given at the 3rd International Meeting on Front End Electronics in Taos, N.M. on Nov. 7,1997. It is based on experience gained by designing and testing the SVX3 128 channel silicon strip detector readout chip. The SVX3 chip organization is shown in Fig. 1. The Front End section consists of an integrator and analog pipeline designed at Fermilab, and the Back End section is an ADC plus sparsification and readout logic designed at LBL. SVX3 is a deadtimeless readout chip, which means that the front end is acquiring low level analog signals while the back end is digitizing and reading out digital signals. It is thus a true mixed signal chip, and demands close attention to avoid disastrous coupling from the digital to the analog sections. SVX3 is designed in a bulk CMOS process (i.e., the circuits sit in a silicon substrate). In such a process, the substrate becomes a potential coupling path. This paper discusses the effect of the substrate resistivity on coupling, and also goes into a more general discussion of grounding and referencing in mixed signal designs and how low resistivity substrates can be used to advantage. Finally, an alternative power supply current conduction method for ASICs is presented as an additional advantage which can be obtained with low resistivity substrates. 1 ref., 13 figs., 1 tab.

  6. Current trends of drug resistance patterns of Acinetobacter baumannii infection in blood transfusion-dependent thalassemia patients

    Directory of Open Access Journals (Sweden)

    Suhail Ahmed Almani

    2017-01-01

    Full Text Available Objective: The present study aimed to evaluate the current trends of drug resistance patterns of Acinetobacter baumannii infection in blood transfusion-dependent thalassemia patients. Study Design: This study was a cross sectional study, conducted at the Liaquat University of Medical and Health Sciences, Jamshoro/Hyderabad, Sindh, Pakistan from October 2014 to January 2016. Subjects and Methods: Of 921 blood samples, A. baumannii strains were isolated from 100 blood samples. Blood samples were processed for the isolation, identification, and drugs sensitivity as per the Clinical and Laboratory Standards Institute. A. baumannii strains were identified by microbiological methods and Gram's staining. API 20 E kit (Biomeriuex, USA was also used for identification. Data were analyzed on Statisti × 8.1 (USA. Results: Mean ± standard deviation age was 11.5 ± 2.8 years. Nearly 70% were male and 30% were female (P = 0.0001. Of 921 blood transfusion-dependent thalassemia patients, 100 (10.8% patients showed growth of A. baumannii. Drug resistance was observed against the ceftazidime, cefixime, cefepime, imipenem, meropenem, amikacin, minocycline, tigecycline, and tazocin except for the colistin. Conclusion: The present study reports drug-resistant A. baumannii in blood transfusion-dependent thalassemia patients. National multicenter studies are recommended to estimate the size of the problem.

  7. Current Trends of Drug Resistance Patterns of Acinetobacter baumannii Infection in Blood Transfusion-dependent Thalassemia Patients.

    Science.gov (United States)

    Almani, Suhail Ahmed; Naseer, Ali; Maheshwari, Sanjay Kumar; Maroof, Pir; Naseer, Raza; Khoharo, Haji Khan

    2017-01-01

    The present study aimed to evaluate the current trends of drug resistance patterns of Acinetobacter baumannii infection in blood transfusion-dependent thalassemia patients. This study was a cross sectional study, conducted at the Liaquat University of Medical and Health Sciences, Jamshoro/Hyderabad, Sindh, Pakistan from October 2014 to January 2016. Of 921 blood samples, A. baumannii strains were isolated from 100 blood samples. Blood samples were processed for the isolation, identification, and drugs sensitivity as per the Clinical and Laboratory Standards Institute. A. baumannii strains were identified by microbiological methods and Gram's staining. API 20 E kit (Biomeriuex, USA) was also used for identification. Data were analyzed on Statisti × 8.1 (USA). Mean ± standard deviation age was 11.5 ± 2.8 years. Nearly 70% were male and 30% were female ( P = 0.0001). Of 921 blood transfusion-dependent thalassemia patients, 100 (10.8%) patients showed growth of A. baumannii . Drug resistance was observed against the ceftazidime, cefixime, cefepime, imipenem, meropenem, amikacin, minocycline, tigecycline, and tazocin except for the colistin. The present study reports drug-resistant A. baumannii in blood transfusion-dependent thalassemia patients. National multicenter studies are recommended to estimate the size of the problem.

  8. Spatially uniform resistance switching of low current, high endurance titanium–niobium-oxide memristors

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, Suhas [Hewlett Packard Labs, Palo Alto, CA (United States); Davila, Noraica [Hewlett Packard Labs, Palo Alto, CA (United States); Wang, Ziwen [Stanford Univ., CA (United States); Huang, Xiaopeng [Hewlett Packard Labs, Palo Alto, CA (United States); Strachan, John Paul [Hewlett Packard Labs, Palo Alto, CA (United States); Vine, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); David Kilcoyne, A. L. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Nishi, Yoshio [Stanford Univ., CA (United States); Stanley Williams, R. [Hewlett Packard Labs, Palo Alto, CA (United States)

    2016-11-24

    Here we analyzed micrometer-scale titanium-niobium-oxide prototype memristors, which exhibited low write-power (< 3 μW) and energy (< 200 fJ per bit per μm2), low read-power (~nW), and high endurance ( > millions of cycles). To understand their physico-chemical operating mechanisms, we performed in operando synchrotron X-ray transmission nanoscale spectromicroscopy using an ultra-sensitive time-multiplexed technique. We observed only spatially uniform material changes during cell operation, in sharp contrast to the frequently detected formation of a localized conduction channel in transition-metal-oxide memristors. We also associated the response of assigned spectral features distinctly to non-volatile storage (resistance change) and writing of information (application of voltage and Joule heating). Lastly, these results provide critical insights into high-performance memristors that will aid in device design, scaling and predictive circuit-modeling, all of which are essential for the widespread deployment of successful memristor applications.

  9. Methicillin-resistant Staphylococcus aureus infections: A review of the currently available treatment options.

    Science.gov (United States)

    Purrello, S M; Garau, J; Giamarellos, E; Mazzei, T; Pea, F; Soriano, A; Stefani, S

    2016-12-01

    This review is the result of discussions that took place at the 5th MRSA Working Group Consensus Meeting and explores the possible treatment options available for different types of infections due to methicillin-resistant Staphylococcus aureus (MRSA), focusing on those antibiotics that could represent a valid alternative to vancomycin. In fact, whilst vancomycin remains a viable option, its therapy is moving towards individualised dosing. Other drugs, such as the new lipoglycopeptides (oritavancin, dalbavancin and telavancin) and fifth-generation cephalosporins (ceftaroline and ceftobiprole), are showing good in vitro potency and in vivo efficacy, especially for patients infected with micro-organisms with higher vancomycin minimum inhibitory concentrations (MICs). Tedizolid is an attractive agent for use both in hospital and community settings, but the post-marketing data will better clarify its potential. Daptomycin and linezolid have shown non-inferiority to vancomycin in the treatment of MRSA bacteraemia and non-inferiority/superiority to vancomycin in the treatment of hospital-acquired pneumonia. Thus, several options are available, but more data from clinical practice, especially for invasive infections, are needed to assign specific roles to each antibiotic and to definitely include them in the new antibacterial armamentarium. Copyright © 2016 International Society for Chemotherapy of Infection and Cancer. Published by Elsevier Ltd. All rights reserved.

  10. Prediction of liquid metal alloy radiant properties from measurements of the Hall coefficient and the direct current resistivity

    International Nuclear Information System (INIS)

    Havstad, M.A.; Qiu, T.

    1995-04-01

    The thermal radiative properties of high temperature solid and liquid metal alloys are particularly useful to research and development efforts in laser cladding and machining, electron beam welding and laser isotope separation. However the cost, complexity, and difficulty of measuring these properties have forced the use of crude estimates from the Hagen-Rubens relation, the Drude relations, or extrapolation from low temperature or otherwise flawed data (e.g., oxidized). The authors have found in this work that published values for the Hall coefficient and the electrical resistivity of liquid metal alloys can provide useful estimates of the reflectance and emittance of some groups of binary liquid metal and high temperature solid alloys. The estimation method computes the Drude free electron parameters, and thence the optical constants and the radiant properties from the dependence of the Hall coefficient and direct current resistivity on alloy composition (the Hall coefficient gives the free electron density and the resistivity gives the average time between collisions). They find that predictions of the radiant properties of molten cerium-copper alloy, which use the measured variations in the Hall coefficient and resistivity (both highly nonlinear) as a function of alloy fraction (rather than linear combinations of the values of the pure elements) yield a good comparison to published measurements of the variation of the normal spectral emittance (a different but also nonlinear function) of cerium-copper alloy at the single wavelength available for comparison, 0.645 μm. The success of the approach in the visible range is particularly notable because one expects a Drude based approach to improve with increasing wavelength from the visible into the infrared. Details of the estimation method, the comparison between the calculation and the measured emittance, and a discussion of what groups of elements may also provide agreement is given

  11. Clinical pilot study of transcranial direct current stimulation combined with Cognitive Emotional Training for medication resistant depression.

    Science.gov (United States)

    Martin, D M; Teng, J Z; Lo, T Y; Alonzo, A; Goh, T; Iacoviello, B M; Hoch, M M; Loo, C K

    2018-05-01

    While the clinical results from transcranial direct current stimulation (tDCS) for the treatment of depression have been promising, antidepressant effects in patients with medication resistance have been suboptimal. There is therefore a need to further optimise tDCS for medication resistant patients. In this clinical pilot study we examined the feasibility, safety, and clinical efficacy of combining tDCS with a psychological intervention which targets dysfunctional circuitry related to emotion regulation in depression, Cognitive Emotional Training (CET). tDCS was administered during CET three times a week for a total of 18 sessions over 6 weeks. Mood, cognition and emotion processing outcomes were examined at baseline and after 3 and 6 weeks of treatment. Twenty patients with medication resistant depression participated, of whom 17 were study completers. tDCS combined with CET was found to be feasible, safe, and associated with significant antidepressant efficacy at 6 weeks, with 41% of study completers showing treatment response (≥ 50% improvement in depression score). There were no significant cognitive enhancing effects with the exception of improved emotion recognition. Responders demonstrated superior recognition for the emotions fear and surprise at pre-treatment compared to non-responders, suggesting that better pre-treatment emotion recognition may be associated with antidepressant efficacy. This was an open label study. tDCS combined with CET has potential as a novel method for optimising the antidepressant efficacy of tDCS in medication resistant patients. Future controlled studies are required to determine whether tDCS combined with CET has greater antidepressant efficacy compared to either intervention alone. Copyright © 2018 Elsevier B.V. All rights reserved.

  12. Drug-resistant epilepsy: current recommendations for diagnosis and treatment in Spain.

    Science.gov (United States)

    Sánchez-Álvarez, J C; Gil-Nagel, A; Casas-Fernández, C; Mauri-Llerda, J A; Salas-Puig, J; Sancho-Rieger, J

    2012-01-01

    Drug-resistant epilepsy (DRE) is a top-priority social health problem which requires early individual treatment due to its dramatic repercussions for the patient and society. The International League Against Epilepsy (ILAE) has recently defined DRE as that in which the seizures are not controlled after having correctly taken two appropriate and well tolerated anti-epileptic drugs, with lack of control being understood as the appearance of seizures within one year or in a period less than three times the inter-seizure interval before starting treatment. This International Society recommends a rapid and detailed assessment of all patients in an Epilepsy Unit. A Clinical Epilepsy Unit (CEU) is understood as a group of professionals who, acting in collaboration, have the diagnosis and treatment of the patient with epilepsy as their primary objective. CEUs in Spain may be stratified into different levels depending on the activity carried out in each of them. The specific epilepsy clinic is considered the fundamental type of CEU and includes the necessary figure of an expert in epilepsy. Prolonged video-monitoring is performed in medical CEUs. In medical-surgical CEUs epilepsy surgery with varying degrees of difficulty is also performed. All CEUs must cooperate with consensus protocols, and there must be a two-way flow between them. Stratification of CEUs increases efficacy and efficiency, due to there being a sufficient number of them to ensure easy access by all patients with epilepsy. © 2011 Sociedad Española de Neurología. Published by Elsevier Espana. All rights reserved.

  13. Microscopic origin of read current noise in TaOx-based resistive switching memory by ultra-low temperature measurement

    Science.gov (United States)

    Pan, Yue; Cai, Yimao; Liu, Yefan; Fang, Yichen; Yu, Muxi; Tan, Shenghu; Huang, Ru

    2016-04-01

    TaOx-based resistive random access memory (RRAM) attracts considerable attention for the development of next generation nonvolatile memories. However, read current noise in RRAM is one of the critical concerns for storage application, and its microscopic origin is still under debate. In this work, the read current noise in TaOx-based RRAM was studied thoroughly. Based on a noise power spectral density analysis at room temperature and at ultra-low temperature of 25 K, discrete random telegraph noise (RTN) and continuous average current fluctuation (ACF) are identified and decoupled from the total read current noise in TaOx RRAM devices. A statistical comparison of noise amplitude further reveals that ACF depends strongly on the temperature, whereas RTN is independent of the temperature. Measurement results combined with conduction mechanism analysis show that RTN in TaOx RRAM devices arises from electron trapping/detrapping process in the hopping conduction, and ACF is originated from the thermal activation of conduction centers that form the percolation network. At last, a unified model in the framework of hopping conduction is proposed to explain the underlying mechanism of both RTN and ACF noise, which can provide meaningful guidelines for designing noise-immune RRAM devices.

  14. Effect of current density on the microstructure and corrosion resistance of microarc oxidized ZK60 magnesium alloy.

    Science.gov (United States)

    You, Qiongya; Yu, Huijun; Wang, Hui; Pan, Yaokun; Chen, Chuanzhong

    2014-09-01

    The application of magnesium alloys as biomaterials is limited by their poor corrosion behavior. Microarc oxidation (MAO) treatment was used to prepare ceramic coatings on ZK60 magnesium alloys in order to overcome the poor corrosion resistance. The process was conducted at different current densities (3.5 and 9.0 A/dm(2)), and the effect of current density on the process was studied. The microstructure, elemental distribution, and phase composition of the MAO coatings were characterized by scanning electron microscopy, energy-dispersive x-ray spectrometry, and x-ray diffraction, respectively. The increment of current density contributes to the increase of thickness. A new phase Mg2SiO4 was detected as the current density increased to 9.0 A/dm(2). A homogeneous distribution of micropores could be observed in the coating produced at 3.5 A/dm(2), while the surface morphology of the coating formed at 9.0 A/dm(2) was more rough and apparent microcracks could be observed. The coating obtained at 3.5 A/dm(2) possessed a better anticorrosion behavior.

  15. Increase in operation safety of high-current pulsed accelerators by means of nonlinear resistances

    International Nuclear Information System (INIS)

    Demidov, B.A.; Ivkin, M.V.; Petrov, V.A.; Fanchenko, S.D.

    1975-01-01

    A circuit for connecting a shaping line through a nonlinear resistor in a high-current pulsed accelerator is proposed and investigated experimentally. For experimental purposes standard resistors are used as nonlinear resistors, they are made in the form of cylinders 100 mm in dia and 60 mm long. The results obtained show that if two resistors are connected in series, the reduction in an initial potential is less than 5% at the logarithmic damping coefficient equal to 1.3. It is also shown that such a method allows elimination of the reverse pumpover of energy to the storage device for untimely actuation of a spark gap that results in the prolongation of the time of potential applying thereby it permits a substantial increase in the reliability of a high-voltage insulation [ru

  16. Extremely Severe Space Weather and Geomagnetically Induced Currents in Regions with Locally Heterogeneous Ground Resistivity

    Science.gov (United States)

    Fujita, Shigeru; Kataoka, Ryuho; Pulkkinen, Antti; Watari, Shinichi

    2016-01-01

    Large geomagnetically induced currents (GICs) triggered by extreme space weather events are now regarded as one of the serious natural threats to the modern electrified society. The risk is described in detail in High-Impact, Low-Frequency Event Risk, A Jointly-Commissioned Summary Report of the North American Electric Reliability Corporation and the US Department of Energy's November 2009 Workshop, June 2010. For example, the March 13-14,1989 storm caused a large-scale blackout affecting about 6 million people in Quebec, Canada, and resulting in substantial economic losses in Canada and the USA (Bolduc 2002). Therefore, European and North American nations have invested in GIC research such as the Solar Shield project in the USA (Pulkkinen et al. 2009, 2015a). In 2015, the Japanese government (Ministry of Economy, Trade and Industry, METI) acknowledged the importance of GIC research in Japan. After reviewing the serious damages caused by the 2011 Tohoku-Oki earthquake, METI recognized the potential risk to the electric power grid posed by extreme space weather. During extreme events, GICs can be concerning even in mid- and low-latitude countries and have become a global issue.

  17. Vitamin D Status and the Host Resistance to Infections: What It Is Currently (Not) Understood.

    Science.gov (United States)

    Lang, Pierre Olivier; Aspinall, Richard

    2017-05-01

    Vitamin D is increasingly thought to play a role in regulating immunity. This comprehensive review updates the current understanding regarding ways in which we believe that vitamin D regulates responsiveness of the immune system and how serum status modulates the host defense against pathogens. The literature was searched by using PubMed and Scopus with the following key words: vitamin D, immunity, innate and adaptive immunity, infectious disease, and vaccine response. Vitamin D deficiency remains a major public health concern worldwide. The overall body of evidence confirms that vitamin D plays an important role in modulating the immune response to infections. Epidemiologic studies suggest a clear association between vitamin D deficiency and susceptibility to various pathogens. However, translation of vitamin D use into the clinic as a means of controlling infections is fraught with methodologic and epidemiologic challenges. The recent discovery of alternative activation pathways, different active forms of vitamin D, and possible interaction with non-vitamin D receptors provide further complications to an already complex interaction between vitamin D and the immune system. Moreover, it has become apparent that the individual responsiveness to supplementation is more dynamic than presumed from the static assessment of 25-hydroxy vitamin D status. Furthermore, the epigenetic response at the level of the individual to environmental changes and lifestyle or health conditions provides greater variation than those resulting from vitamin D receptor polymorphisms. To understand the future of vitamin D with respect to clinical applications in the prevention and better control of infectious diseases, it is necessary to determine all aspects of vitamin D metabolism, as well as the mechanisms by which active forms interact with the immune system globally. For the most part, we are unable to identify tissue-specific applications of supplementation except for those subjects at

  18. In situ determination of the static inductance and resistance of a plasma focus capacitor bank

    Science.gov (United States)

    Saw, S. H.; Lee, S.; Roy, F.; Chong, P. L.; Vengadeswaran, V.; Sidik, A. S. M.; Leong, Y. W.; Singh, A.

    2010-05-01

    The static (unloaded) electrical parameters of a capacitor bank are of utmost importance for the purpose of modeling the system as a whole when the capacitor bank is discharged into its dynamic electromagnetic load. Using a physical short circuit across the electromagnetic load is usually technically difficult and is unnecessary. The discharge can be operated at the highest pressure permissible in order to minimize current sheet motion, thus simulating zero dynamic load, to enable bank parameters, static inductance L0, and resistance r0 to be obtained using lightly damped sinusoid equations given the bank capacitance C0. However, for a plasma focus, even at the highest permissible pressure it is found that there is significant residual motion, so that the assumption of a zero dynamic load introduces unacceptable errors into the determination of the circuit parameters. To overcome this problem, the Lee model code is used to fit the computed current trace to the measured current waveform. Hence the dynamics is incorporated into the solution and the capacitor bank parameters are computed using the Lee model code, and more accurate static bank parameters are obtained.

  19. In situ determination of the static inductance and resistance of a plasma focus capacitor bank.

    Science.gov (United States)

    Saw, S H; Lee, S; Roy, F; Chong, P L; Vengadeswaran, V; Sidik, A S M; Leong, Y W; Singh, A

    2010-05-01

    The static (unloaded) electrical parameters of a capacitor bank are of utmost importance for the purpose of modeling the system as a whole when the capacitor bank is discharged into its dynamic electromagnetic load. Using a physical short circuit across the electromagnetic load is usually technically difficult and is unnecessary. The discharge can be operated at the highest pressure permissible in order to minimize current sheet motion, thus simulating zero dynamic load, to enable bank parameters, static inductance L(0), and resistance r(0) to be obtained using lightly damped sinusoid equations given the bank capacitance C(0). However, for a plasma focus, even at the highest permissible pressure it is found that there is significant residual motion, so that the assumption of a zero dynamic load introduces unacceptable errors into the determination of the circuit parameters. To overcome this problem, the Lee model code is used to fit the computed current trace to the measured current waveform. Hence the dynamics is incorporated into the solution and the capacitor bank parameters are computed using the Lee model code, and more accurate static bank parameters are obtained.

  20. In situ determination of the static inductance and resistance of a plasma focus capacitor bank

    Energy Technology Data Exchange (ETDEWEB)

    Saw, S. H. [INTI University College, Nilai 71800 (Malaysia); Institute for Plasma Focus Studies, 32 Oakpark Drive, Chadstone, Victoria 3148 (Australia); Lee, S. [INTI University College, Nilai 71800 (Malaysia); Institute for Plasma Focus Studies, 32 Oakpark Drive, Chadstone, Victoria 3148 (Australia); National Institute of Education, Nanyang Technological University, Singapore 637616 (Singapore); Roy, F.; Chong, P. L.; Vengadeswaran, V.; Sidik, A. S. M.; Leong, Y. W.; Singh, A. [INTI University College, Nilai 71800 (Malaysia)

    2010-05-15

    The static (unloaded) electrical parameters of a capacitor bank are of utmost importance for the purpose of modeling the system as a whole when the capacitor bank is discharged into its dynamic electromagnetic load. Using a physical short circuit across the electromagnetic load is usually technically difficult and is unnecessary. The discharge can be operated at the highest pressure permissible in order to minimize current sheet motion, thus simulating zero dynamic load, to enable bank parameters, static inductance L{sub 0}, and resistance r{sub 0} to be obtained using lightly damped sinusoid equations given the bank capacitance C{sub 0}. However, for a plasma focus, even at the highest permissible pressure it is found that there is significant residual motion, so that the assumption of a zero dynamic load introduces unacceptable errors into the determination of the circuit parameters. To overcome this problem, the Lee model code is used to fit the computed current trace to the measured current waveform. Hence the dynamics is incorporated into the solution and the capacitor bank parameters are computed using the Lee model code, and more accurate static bank parameters are obtained.

  1. In situ determination of the static inductance and resistance of a plasma focus capacitor bank

    International Nuclear Information System (INIS)

    Saw, S. H.; Lee, S.; Roy, F.; Chong, P. L.; Vengadeswaran, V.; Sidik, A. S. M.; Leong, Y. W.; Singh, A.

    2010-01-01

    The static (unloaded) electrical parameters of a capacitor bank are of utmost importance for the purpose of modeling the system as a whole when the capacitor bank is discharged into its dynamic electromagnetic load. Using a physical short circuit across the electromagnetic load is usually technically difficult and is unnecessary. The discharge can be operated at the highest pressure permissible in order to minimize current sheet motion, thus simulating zero dynamic load, to enable bank parameters, static inductance L 0 , and resistance r 0 to be obtained using lightly damped sinusoid equations given the bank capacitance C 0 . However, for a plasma focus, even at the highest permissible pressure it is found that there is significant residual motion, so that the assumption of a zero dynamic load introduces unacceptable errors into the determination of the circuit parameters. To overcome this problem, the Lee model code is used to fit the computed current trace to the measured current waveform. Hence the dynamics is incorporated into the solution and the capacitor bank parameters are computed using the Lee model code, and more accurate static bank parameters are obtained.

  2. Extensively Drug-resistant Tuberculosis (XDR-TB): A daunting challenge to the current End TB Strategy and policy recommendations.

    Science.gov (United States)

    Rahman, Md Arifur; Sarkar, Atanu

    2017-07-01

    Extensively Drug-resistant Tuberculosis (XDR-TB) has emerged as one of the most formidable challenges to the End TB Strategy that has targeted a 95% reduction in TB deaths and 90% reduction in cases by 2035. Globally, there were an estimated 55,100 new XDR-TB cases in 2015 in 117 countries. However, only one in 30 XDR-TB cases had been reported so far. Drug susceptibility test (DST) is the mainstay for diagnosing XDR-TB, but the lack of laboratory facilities in the resource-limited endemic countries limit its uses. A few new drugs including bedaquiline and delamanid, have the potential to improve the efficiency of XDR-TB treatment, but the drugs have been included in 39 countries only. The costs of XDR-TB treatment are several folds higher than that of the MDR-TB. Despite the financing from the donors, there is an urgent need to fill the current funding gap of US$ 2 billion to ensure effective treatment and robust surveillance. In the review article we have addressed current update on XDR-TB, including surveillance, diagnosis and the interventions needed to treat and limit its spread, emphasis on extensive financial support for implementing of current recommendations to meet the goals of End TB Strategy. Copyright © 2017 Tuberculosis Association of India. Published by Elsevier B.V. All rights reserved.

  3. Influence of welding current in resistance spot welding on the properties of Zn coated steel DX51D

    Directory of Open Access Journals (Sweden)

    Luboš Kaščák

    2016-06-01

    Full Text Available The paper deals with the resistance spot welding of three galvanized car body sheets DX51D + Z - EN 10142/2000. The quality of welded joints was evaluated by destructive tests and non-destructive tests. For evaluation of joints quality the shear tension test on spot joints according to DIN 50 124 standard was used. The influence of welding parameters on the structure of a welded joint was observed by metallographic analysis. Influence of welding current from 6.0 to 7.7 kA and influence of welding time from 10 to 12 periods on weld properties was observed. Increasing the welding current led to increased load-bearing capacity of the welded joints. The spot welded joints without any internal defects occurred in samples welded up to 7.0 kA. Increasing the welding time to 12 periods led to increased load-bearing capacity of the welded joints, within all observed values of welding current.

  4. INVESTIGATION OF ADAPTIVE MICRO-PROCESSOR CURRENT PROTECTION OF 6–35 kV

    Directory of Open Access Journals (Sweden)

    F. A. Romaniuk

    2007-01-01

    Full Text Available Main indices pertaining to technical updating of adaptive micro-processor current protection of 6-35 kV have been obtained. The calculative experiment has made it possible to determine signal dependences in various protection circuits with double-phase and triple-phase short circuits at the beginning of the protected line. Evaluation of time operation of all stages and protection sensitivity has been carried out. 

  5. Definition of the electric requirements for the equipment associated to the limiter reactor on a 550 kV line occurring from manoeuvres under short circuits; Definicao dos requisitos eletricos dos equipamentos associados ao reator limitador em 550 kV, em decorrencia de manobras sob curtos-circuitos

    Energy Technology Data Exchange (ETDEWEB)

    Machado Junior, Camilo; Furuoka, Nita; Rose, Eber Havila [ELETRONORTE, Brasilia, DF (Brazil)]. E-mail: eber@eln.gov.br; Violin, Airton; Martinez, Manuel Luis Barreira [Escola Federal de Engenharia de Itajuba (EFEI), MG (Brazil). Inst. de Engenharia Eletrica. Lab. de Alta Tensao; Saraiva, Carlos Alberto Moura [Consorcio THEMAG-ENGEVIX, Sao Paulo, SP (Brazil)

    2001-07-01

    This paper presents the ascertaining based on the TRT study results performed to the definition of the new circuit breakers characteristics for the second stage of the Tucurui hydroelectric power plant, placed at the northern Brazil and with final configuration of two power houses and two air isolated substations, amounting 9 GVA. To reduce the short-circuit level to satisfactory values series reactors were used among the 550 kV substations. The result of the studies associated to the circuit breaker specifications are presented.

  6. A Very Low Dark Current Temperature-Resistant, Wide Dynamic Range, Complementary Metal Oxide Semiconductor Image Sensor

    Science.gov (United States)

    Mizobuchi, Koichi; Adachi, Satoru; Tejada, Jose; Oshikubo, Hiromichi; Akahane, Nana; Sugawa, Shigetoshi

    2008-07-01

    A very low dark current (VLDC) temperature-resistant approach which best suits a wide dynamic range (WDR) complementary metal oxide semiconductor (CMOS) image sensor with a lateral over-flow integration capacitor (LOFIC) has been developed. By implementing a low electric field photodiode without a trade-off of full well-capacity, reduced plasma damage, re-crystallization, and termination of silicon-silicon dioxide interface states in the front end of line and back end of line (FEOL and BEOL) in a 0.18 µm, two polycrystalline silicon, three metal (2P3M) process, the dark current is reduced to 11 e-/s/pixel (0.35 e-/s/µm2: pixel area normalized) at 60 °C, which is the lowest value ever reported. For further robustness at low and high temperatures, 1/3-in., 5.6-µm pitch, 800×600 pixel sensor chips with low noise readout circuits designed for a signal and noise hold circuit and a programmable gain amplifier (PGA) have also been deposited with an inorganic cap layer on a micro-lens and covered with a metal hermetically sealed package assembly. Image sensing performance results in 2.4 e-rms temporal noise and 100 dB dynamic range (DR) with 237 ke- full well-capacity. The operating temperature range is extended from -40 to 85 °C while retaining good image quality.

  7. Multi-scale model of resistive-type superconducting fault current limiters based on 2G HTS coated conductors

    Science.gov (United States)

    Bonnard, Charles-Henri; Sirois, Frédéric; Lacroix, Christian; Didier, Gaëtan

    2017-01-01

    In order to plan the integration of superconducting fault current limiters (SFCLs) in power systems, accurate models of SFCLs must be made available in commercial power system transient simulators. In this context, we developed such a model for the EMTP-RV software package, a power system transient simulator widely used by power utilities. The model can be used with any resistive-type SFCL (rSFCL) made of high temperature superconductor (HTS) tapes, which are discretized in ‘electro-thermal elements’. Those elements consist solely of electric circuit components, and are used to represent portions of tape of various sizes and dimensions (a ‘multi-scale’ approach). Both the electrical and thermal behaviors of the tape are modeled, including interfacial effects, nonlinear properties of materials and heat transfer to the surrounding environment. Such a multi-scale model can simulate accurately both the local quench dynamics of HTS tapes (microscopic scale) and the global impact of the rSFCL on the power system (macroscopic/system scale). In this paper, the model is used to compute phenomena such as propagation velocity of a hot spot and heat diffusion through the thickness of the tape. Results were verified by comparing EMTP-RV results with finite element simulations. In addition to the development of the multi-scale model itself, which is the major contribution of this paper, the use of the model allowed us to determine the conditions of validity of the commonly used ‘homogenization’ of the thermal properties across the tape thickness. Indeed, when the current flowing into the rSFCL is slightly above its critical current I c (and up to 2{I}{{c}}), very important errors in the power waveforms arise, leading to potentially wrong decisions of protection systems. Homogenized thermal models should thus be used with great care in practice.

  8. Soft X-ray beam induced current technique

    Energy Technology Data Exchange (ETDEWEB)

    Watts, B; Ade, H [Department of Physics, North Carolina State University, Raleigh, NC 27695 (United States); Queen, D; Hellman, F [Department of Physics, University of California, Berkeley, CA 94720 (United States); Kilcoyne, A L D; Tyliszczak, T, E-mail: benjamin.watts@gmail.co [Advanced Light Source, Lawrence Berkeley Nat. Lab., Berkeley, CA 94720 (United States)

    2009-09-01

    Direct mapping of the charge transport efficiency of polymer solar cell devices using a soft X-ray beam induced current (SoXBIC) method is described. By fabricating a polymer solar cell on an x-ray transparent substrate, we demonstrate the ability to map polymer composition and nanoscale structure within an operating solar cell device and to simultaneously measure the local charge transport efficiency via the short-circuit current. A simple model is calculated and compared to experimental SoXBIC data of a PFB:F8BT bulk-heterojunction device in order to gain greater insight into the device operation and physics.

  9. Bipolar and unipolar resistive switching behaviors of sol–gel-derived SrTiO3 thin films with different compliance currents

    International Nuclear Information System (INIS)

    Tang, M H; Wang, Z P; Zeng, Z Q; Xu, X L; Wang, G Y; Zhang, L B; Xiao, Y G; Yang, S B; Jiang, B; Li, J C; He, J

    2011-01-01

    The SrTiO 3 (STO) thin films on a Pt/Ti/SiO 2 /Si substrate were synthesized using a sol–gel method to form a metal–insulator–metal structure. This device shows the bipolar resistance switching (BRS) behavior for a compliance current I cc of less than 0.1 mA but exhibits soft breakdown at a higher level of compliance current. A transition from the BRS behavior to the stable unipolar resistive switching behavior (URS) was also observed. We found that the BRS behavior may be controlled by the structure interface while the URS behavior is likely bulk controlled. Our study indicates that the external compliance current is a key factor in resistance switching phenomenon of STO thin films

  10. Effect of current compliance and voltage sweep rate on the resistive switching of HfO2/ITO/Invar structure as measured by conductive atomic force microscopy

    Science.gov (United States)

    Wu, You-Lin; Liao, Chun-Wei; Ling, Jing-Jenn

    2014-06-01

    The electrical characterization of HfO2/ITO/Invar resistive switching memory structure was studied using conductive atomic force microscopy (AFM) with a semiconductor parameter analyzer, Agilent 4156C. The metal alloy Invar was used as the metal substrate to ensure good ohmic contact with the substrate holder of the AFM. A conductive Pt/Ir AFM tip was placed in direct contact with the HfO2 surface, such that it acted as the top electrode. Nanoscale current-voltage (I-V) characteristics of the HfO2/ITO/Invar structure were measured by applying a ramp voltage through the conductive AFM tip at various current compliances and ramp voltage sweep rates. It was found that the resistance of the low resistance state (RLRS) decreased with increasing current compliance value, but resistance of high resistance state (RHRS) barely changed. However, both the RHRS and RLRS decreased as the voltage sweep rate increased. The reasons for this dependency on current compliance and voltage sweep rate are discussed.

  11. A Randomized Double-Blind Sham-Controlled Study of Transcranial Direct Current Stimulation for Treatment-Resistant Major Depression

    Directory of Open Access Journals (Sweden)

    Daniel eBlumberger

    2012-08-01

    Full Text Available Objectives: Transcranial direct current stimulation (tDCS has demonstrated some efficacy in treatment-resistant major depression (TRD. The majority of previous controlled studies have used anodal stimulation to the left dorsolateral prefrontal cortex (DLPFC and a control location such as the supraorbital region on for the cathode. Several open label studies have suggested effectiveness from anodal stimulation to the left DLPFC combined with cathodal stimulation to the right DLPFC. Thus, this study evaluated the efficacy of tDCS using anodal stimulation to the left DLPFC and cathodal stimulation to the right DLPFC compared to sham tDCS. Methods: Subjects between the ages of 18 and 65 were recruited from a tertiary care university hospital. Twenty-four subjects with TRD and a 17-item Hamilton Depression Rating Scale (HDRS greater than 21 were randomized to receive tDCS or sham tDCS. The rates of remission were compared between the two treatment groups.Results: The remission rates did not differ significantly between the two groups using an intention to treat analysis. More subjects in the active tDCS group had failed a course of electroconvulsive therapy in the current depressive episode. Side effects did not differ between the two groups and in general the treatment was very well tolerated. Conclusion: Anodal stimulation to the left DLPFC and cathodal stimulation to the right DLPFC was not efficacious in TRD. However, a number of methodological limitations warrant caution in generalizing from this study. Ongoing, controlled studies should provide further clarification on the efficacy of this stimulation configuration in TRD.

  12. Current and developing therapies for the treatment of multi drug resistant tuberculosis (MDR-TB) in India.

    Science.gov (United States)

    Muniyandi, Malaisamy; Ramachandran, Rajeswari

    2017-09-01

    India accounts for 25% of the global burden of MDR-TB. In 2016, the India's Revised National TB Control Programme reported a success rate of 46% among 19,298 MDR-TB patients treated under the programme. This suboptimal treatment outcome warrants an urgent need for newer drugs and newer regimens in the treatment of MDR-TB. India requires new shorter, cheap, safe and effective anti-TB regimen to treat MDR-TB. Areas covered: We used different search strategies to obtain relevant literature from PubMed, on Indian experiences of developing therapies for the treatment of MDR-TB. Further information from the Central TB Division Government of India on programmatic management of resistant TB was collected. Expert opinion: In 2016 WHO recommended a shorter MDR-TB regimen of 9-12 months (4-6 Km-Mfx-Pto-Cfz-Z-Hhigh-dose-E /5 Mfx-Cfz-Z-E) may be used instead of longer regimens. Currently, conducting trials involving newer drugs such as bedaquiline, have been proposed. The regimen will be of a shorter duration containing isoniazid, prothionamide, bedaquiline, levofloxacin, ciprofloxacin, ethambutol and pyrazinamide (STREAM regimen). To successfully treat MDR-TB one requires new classes of antibiotic and newer diagnostic tests. This represents an enormous financial and technical challenge to the programme managers and policy makers.

  13. Evaluation of critical current density and residual resistance ratio limits in powder in tube Nb3Sn conductors

    CERN Document Server

    Segal, Christopher; Sung, Zu Hawn; Lee, Peter J; Sailer, Bernd; Thoener, Manfred; Schlenga, Klaud; Ballarino, Amalia; Bottura, Luca; Bordini, Bernardo; Scheuerlein, Christian; Larnalestier, David C

    2016-01-01

    High critical current density ( Jc) Nb3Sn A15 multifilamentary wires require a large volume fraction of small grain (SG), superconducting A15 phase, as well as Cu stabilizer with high Residual Resistance Ratio (RRR) to provide electromagnetic stabilization and protection. In powder-in-tube (PIT) wires the unreacted Nb7.5 wt%Ta outer layer of the tubular filaments acts as a diffusion barrier and protects the interfilamentary Cu stabilizer from Sn contamination. A high RRR requirement generally imposes a restricted A15 reaction heat treatment to prevent localized full reaction of the filament that could allow Sn to reach the Cu. In this study we investigate recent high quality PIT wires that achieve a Jc (12 T, 4.2 K) up to ∼2500 A mm−2 and find that the minimum diffusion barrier thickness decreases as the filament aspect ratio increases from ∼1 in the inner rings of filaments to 1.3 in the outer filament rings. We found that just 2–3 diffusion barrier breaches can degrade RRR from 300 to 150 or less. U...

  14. Multi-Valued Planar Hall Resistance Manipulated by Current Induced Magnetic Field in Fe Films Grown on GaAs(001) Substrates

    Science.gov (United States)

    Khym, Sungwon; Yoo, Taehee; Lee, Hakjoon; Lee, Sangyeop; Lee, Sanghoon; Liu, Xinyu; Furdyna, Jacek K.; Lee, Dong Uk; Kim, Eun Kyu

    2012-09-01

    A Hall device was fabricated from single-crystal Fe film having two in-plane magnetic easy axes. Planar Hall resistance measured by sequential application of current pulses to the metal strip that was deposited on the top of a Hall bar showed a hysteresis similar to that observed by scanning an external magnetic field. It was shown that discrete Hall resistance values in the hysteresis, which correspond to specific multidomain structures in Fe film, can be created by the application of appropriate sequences of current pulses to the metal strip, and can thus be used for read/write logic applications.

  15. Monte Carlo Simulations Suggest Current Chlortetracycline Drug-Residue Based Withdrawal Periods Would Not Control Antimicrobial Resistance Dissemination from Feedlot to Slaughterhouse

    Directory of Open Access Journals (Sweden)

    Casey L. Cazer

    2017-09-01

    Full Text Available Antimicrobial use in beef cattle can increase antimicrobial resistance prevalence in their enteric bacteria, including potential pathogens such as Escherichia coli. These bacteria can contaminate animal products at slaughterhouses and cause food-borne illness, which can be difficult to treat if it is due to antimicrobial resistant bacteria. One potential intervention to reduce the dissemination of resistant bacteria from feedlot to consumer is to impose a withdrawal period after antimicrobial use, similar to the current withdrawal period designed to prevent drug residues in edible animal meat. We investigated tetracycline resistance in generic E. coli in the bovine large intestine during and after antimicrobial treatment by building a mathematical model of oral chlortetracycline pharmacokinetics-pharmacodynamics and E. coli population dynamics. We tracked three E. coli subpopulations (susceptible, intermediate, and resistant during and after treatment with each of three United States chlortetracycline indications (liver abscess reduction, disease control, disease treatment. We compared the proportion of resistant E. coli before antimicrobial use to that at several time points after treatment and found a greater proportion of resistant enteric E. coli after the current withdrawal periods than prior to treatment. In order for the proportion of resistant E. coli in the median beef steer to return to the pre-treatment level, withdrawal periods of 15 days after liver abscess reduction dosing (70 mg daily, 31 days after disease control dosing (350 mg daily, and 36 days after disease treatment dosing (22 mg/kg bodyweight for 5 days are required in this model. These antimicrobial resistance withdrawal periods would be substantially longer than the current U.S. withdrawals of 0–2 days or Canadian withdrawals of 5–10 days. One published field study found similar time periods necessary to reduce the proportion of resistant E. coli following

  16. The genetics of resistance to powdery mildew in cultivated oats (Avena sativa L.): current status of major genes.

    Science.gov (United States)

    Hsam, Sai L K; Mohler, Volker; Zeller, Friedrich J

    2014-05-01

    The genetics of resistance to powdery mildew caused by Blumeria graminis f. sp. avenae of four cultivated oats was studied using monosomic analysis. Cultivar 'Bruno' carries a gene (Pm6) that shows a recessive mode of inheritance and is located on chromosome 10D. Cultivar 'Jumbo' possesses a dominant resistance gene (Pm1) on chromosome 1C. In cultivar 'Rollo', in addition to the gene Pm3 on chromosome 17A, a second dominant resistance gene (Pm8) was identified and assigned to chromosome 4C. In breeding line APR 122, resistance was conditioned by a dominant resistance gene (Pm7) that was allocated to chromosome 13A. Genetic maps established for resistance genes Pm1, Pm6 and Pm7 employing amplified fragment length polymorphism (AFLP) markers indicated that these genes are independent of each other, supporting the results from monosomic analysis.

  17. Investigation of Superficial Resistance of Different Purity Copper at Boiling Nitrogen Temperature Depending on Treatment of Current-Conducting Layer

    International Nuclear Information System (INIS)

    Kutovoj, V.A.; Nikolaenko, A.A.; Stoev, P.I.

    2007-01-01

    Results of this scientific work show influence of annealing temperature and deformation degree of initial MOB copper and after electron beam refining on superficial resistance at temperature of boiling nitrogen. It is shown, that 30 % deformation and annealing in 873...923 K temperature range results in appreciable reduction of superficial resistance at the investigated samples of copper. The lowest values of superficial resistance after thermal and mechanical treatment were observed in the samples after electron beam refinement

  18. Harmonic current control for LCL-filtered VSCs connected to ultra-weak grids

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Yang, Dongsheng; Blaabjerg, Frede

    2017-01-01

    control scheme is thus proposed by feeding back the filter capacitor voltage and the converter-side current. The method not only stabilizes the harmonic current control with a wide range of SCR values, but also mitigates harmonic distortions in the grid-side current of the VSC. The stabilizing mechanism......This paper addresses the harmonic current control for LCL-filtered Voltage-Source Converters (VSCs) connected to ultra-weak (high-impedance) grids. It is shown that the harmonic current controllers tend to be unstable as the Short-Circuit Ratio (SCR) of the system reduces. An active stabilizing...

  19. Two dimensional joint inversion of direct current resistivity, radio-magnetotelluric and seismic refraction data: An application from Bafra Plain, Turkey

    Science.gov (United States)

    Demirci, İsmail; Candansayar, Mehmet Emin; Vafidis, Antonis; Soupios, Pantelis

    2017-04-01

    Direct current resistivity, radio-magnetotelluric and seismic refraction methods are widely used in the identification of near surface structures with collected data generally being interpreted separately. In recent decades, the use of joint inversion algorithms in geosciences has become widespread to identify near surface structures. However, there is no developed joint inversion algorithm using direct current resistivity, radio-magnetotelluric and seismic refraction methods. In this study, we developed a new two-dimensional joint inversion algorithm for direct current resistivity, radio-magnetotelluric and seismic refraction data based on a cross gradient approach. In addition, we proposed a new data weighting matrix to stabilize the convergence behavior of the joint inversion algorithms. We used synthetic data to show the advantage of the algorithm. The developed joint inversion algorithm found resistivity and velocity models that are better than the individual inversion of each data set. We also tested an algorithm with the field data collected in the Bafra Plain (Samsun, Turkey) to investigate saltwater intrusion. In comparing the field data inversion results with the sounding log, it can be seen that the developed joint inversion algorithm with the proposed data weighting matrix recovered the resistivity and velocity model better than the individual inversion and classical joint inversion of each data set. Our results showed that a more unique hydrogeological scenario might be obtained, especially in highly conductive media, with the joint usage of these methods.

  20. Fault current limiter with solid-state circuit breakers

    Science.gov (United States)

    Bălan, H.; Neamț, L.; Buzdugan, M. I.; Varodi, T.; Pop, E.

    2016-08-01

    Switching of power circuit breakers is an important technical issue, especially at short circuit, since the fault current cause thermal and dynamic stresses, and the power quality worsens. Recently, the development of distributed renewable electricity induces the short circuit protection problematic because the distributed production of electric energy cause the transport networks to lose their radial character and disturbs the protective relays coordination. The modern technologies for power switching uses static fault current limiters, which offers a viable solution to remove the problems caused by large fault currents in the system. An appropriate design of the current limiting device reduces the thermal and dynamic stress and limits the fault current to a low value. The static switches are based on high power semiconductor devices that offer advantages compared to mechanical switches. Using a fault current limiter that minimizes the effect of distributed generation of electricity in a radial network on the co-ordination of protective relays is a solution to this problem in terms of switching speed and lifespan of power switches.

  1. Control scheme for photovoltaic three-phase inverters to minimize peak currents during unbalanced grid-voltage sags

    OpenAIRE

    Miret Tomàs, Jaume; Castilla Fernández, Miguel; Camacho Santiago, Antonio; García de Vicuña Muñoz de la Nava, José Luis; Matas Alcalá, José

    2012-01-01

    Nowadays, the majority of the photovoltaic (PV) power sources are connected to the public grid. One of the main connection problems occurs when voltage sags appear in the grid due to short circuits, lightning, etc. International standards regulate the grid connection of PV systems, forcing the source to remain connected during short-time grid-voltage faults. As a consequence, during the voltage sag, the source should operate with increasing converter currents to maintain ...

  2. A Method for Identification of the Equivalent Inductance and Resistance in the Plant Model of Current-Controlled Grid-Tied Converters

    DEFF Research Database (Denmark)

    Vidal, Ana; Yepes, Alejandro G.; Fernandez, Francisco Daniel Freijedo

    2015-01-01

    important uncertainties with respect to the value of the VSC L/LCL interface filter measured at rated conditions. Thus, in this work, a method is presented to estimate both parameters of the plant time constant, i.e., the equivalent inductance and resistance in the plant model of current-controlled VSCs....... The proposed technique is based on the evaluation of the closed-loop transient responses of both axes of the synchronous reference frame when a proportional-integral current controller is implemented. The method gives a set of resistance and inductance values that should be employed for a rigorous design...... for most cases in which an LCL filter is used. As the loop behavior can be significantly influenced by the VSC working conditions, the effects associated to converter losses should be included in the model, through an equivalent series resistance. In addition, the plant inductance may also present...

  3. Emerging epidemic of drug-resistant tuberculosis in Europe, Russia, China, South America and Asia: current status and global perspectives.

    Science.gov (United States)

    Migliori, Giovanni Battista; Centis, Rosella; Lange, Chris; Richardson, Morgan D'Arcy; Sotgiu, Giovanni

    2010-05-01

    Drug resistance, particularly through multidrug-resistant tuberculosis (TB) and extensively drug-resistant TB strains, poses a real threat to TB control worldwide. Recent reports from the WHO and the International Union Against Tuberculosis and Lung Disease demonstrate that the emerging epidemic of drug-resistant TB is a global problem, although emphasis has been placed on several 'hot spots' because of lack of good global data. The present article is aimed at reviewing the available information on drug-resistant TB with special focus on the features of the epidemic in Europe, Russia, Latin America, Asia and specifically China, and to discuss the global perspectives related to drug-resistant TB control and care. Drug-resistant TB originates from different human errors, including misuse of anti-TB drugs and other reasons related to prescribers, patients and drug producers. Although there is an urgent need for new drugs, a sound public health approach is necessary for their introduction in clinical treatment settings to prevent/avoid creating additional resistance, as has already been observed for first and second-line anti-TB drugs in many settings.

  4. Clinical Endocannabinoid Deficiency Reconsidered: Current Research Supports the Theory in Migraine, Fibromyalgia, Irritable Bowel, and Other Treatment-Resistant Syndromes.

    Science.gov (United States)

    Russo, Ethan B

    2016-01-01

    Medicine continues to struggle in its approaches to numerous common subjective pain syndromes that lack objective signs and remain treatment resistant. Foremost among these are migraine, fibromyalgia, and irritable bowel syndrome, disorders that may overlap in their affected populations and whose sufferers have all endured the stigma of a psychosomatic label, as well as the failure of endless pharmacotherapeutic interventions with substandard benefit. The commonality in symptomatology in these conditions displaying hyperalgesia and central sensitization with possible common underlying pathophysiology suggests that a clinical endocannabinoid deficiency might characterize their origin. Its base hypothesis is that all humans have an underlying endocannabinoid tone that is a reflection of levels of the endocannabinoids, anandamide (arachidonylethanolamide), and 2-arachidonoylglycerol, their production, metabolism, and the relative abundance and state of cannabinoid receptors. Its theory is that in certain conditions, whether congenital or acquired, endocannabinoid tone becomes deficient and productive of pathophysiological syndromes. When first proposed in 2001 and subsequently, this theory was based on genetic overlap and comorbidity, patterns of symptomatology that could be mediated by the endocannabinoid system (ECS), and the fact that exogenous cannabinoid treatment frequently provided symptomatic benefit. However, objective proof and formal clinical trial data were lacking. Currently, however, statistically significant differences in cerebrospinal fluid anandamide levels have been documented in migraineurs, and advanced imaging studies have demonstrated ECS hypofunction in post-traumatic stress disorder. Additional studies have provided a firmer foundation for the theory, while clinical data have also produced evidence for decreased pain, improved sleep, and other benefits to cannabinoid treatment and adjunctive lifestyle approaches affecting the ECS.

  5. Transmission of HIV Drug Resistance and the Predicted Effect on Current First-line Regimens in Europe

    DEFF Research Database (Denmark)

    Hofstra, L Marije; Sauvageot, Nicolas; Albert, Jan

    2016-01-01

    BACKGROUND:  Numerous studies have shown that baseline drug resistance patterns may influence the outcome of antiretroviral therapy. Therefore, guidelines recommend drug resistance testing to guide the choice of initial regimen. In addition to optimizing individual patient management......, these baseline resistance data enable transmitted drug resistance (TDR) to be surveyed for public health purposes. The SPREAD program systematically collects data to gain insight into TDR occurring in Europe since 2001. METHODS:  Demographic, clinical, and virological data from 4140 antiretroviral-naive human...... immunodeficiency virus (HIV)-infected individuals from 26 countries who were newly diagnosed between 2008 and 2010 were analyzed. Evidence of TDR was defined using the WHO list for surveillance of drug resistance mutations. Prevalence of TDR was assessed over time by comparing the results to SPREAD data from 2002...

  6. Study of complex resistivity measurement using current and potential waveform data; Denryu to den`i hakei data wo riyoshita fukusohi teiko sokutei no kento

    Energy Technology Data Exchange (ETDEWEB)

    Shima, H.; Sakurai, K.; Yamashita, Y. [OYO Corp., Tokyo (Japan)

    1997-10-22

    This paper proposes a measurement method for complex resistivity using both current and potential waveforms. This method was applied to actual data. Especially, chargeability was discussed among complex resistivities. A method was proposed for determining the complex resistivity. At first, digital measurements of both current and potential waveforms were conducted. For the potential waveform, zero-order self-potential was canceled. Then, the FFT technique was applied to both current and potential waveforms, to determine both current and potential in the frequency domain. Hereafter, complex resistivity was determined through simple division. Since the inductive coupling was observed at higher frequencies, it was difficult to apply Cole-Cole model, simply. However, the inductive coupling could be removed using proper sampling frequency. Thus, a proper Cole-Cole dispersion curve could be obtained. Using this Cole-Cole dispersion curve, new chargeability could be defined. A linear relation between this chargeability and the ordinary time domain chargeability was made clear. 4 refs., 10 figs.

  7. Graphene, conducting polymer and their composites as transparent and current spreading electrode in GaN solar cells

    Science.gov (United States)

    Mahala, Pramila; Kumar, Ajay; Nayak, Sasmita; Behura, Sanjay; Dhanavantri, Chenna; Jani, Omkar

    2016-04-01

    Understanding the physics of charge carrier transport at graphene/p-GaN interface is critical for achieving efficient device functionality. Currently, the graphene/p-GaN interface is being explored as light emitting diodes, however this interface can be probed as a potential photovoltaic cell. We report the intimate interfacing of mechanically exfoliated graphene (EG), conducting polymer (PEDOT:PSS) and composite of reduced graphene oxide (rGO) and PEDOT:PSS with a wide band gap p-GaN layer. To explore their potential in energy harvesting, three heterojunction devices such as: (i) EG/p-GaN/sapphire, (ii) PEDOT:PSS/p-GaN/sapphire and (iii) PEDOT:PSS(rGO)/p-GaN/sapphire are designed and their photovoltaic characteristics are examined. It is interesting to observe that the EG/p-GaN/sapphire solar cell exhibits high open-circuit voltage of 0.545 V with low ideality factor and reverse saturation current. However, improved short circuit current density (13.7 mA/cm2) is noticed for PEDOT:PSS/p-GaN/sapphire solar cell because of enhanced conductivity accompanied by high transmittance for PEDOT:PSS. Further, the low series resistance for PEDOT:PSS(rGO)/p-GaN/sapphire is observed suggesting that the PEDOT:PSS and rGO composite is well dispersed and exhibits low interfacial resistances with p-GaN. The present investigation leverages the potential of graphene, conducting polymer and their composites as dual capability of (a) transparent and current spreading electrode and (b) an active top layer to make an intimate contact with wide bandgap p-type GaN for possible prospect towards high performance diodes, switches and solar cells.

  8. Pigments from UV-resistant Antarctic bacteria as photosensitizers in Dye Sensitized Solar Cells.

    Science.gov (United States)

    Órdenes-Aenishanslins, N; Anziani-Ostuni, G; Vargas-Reyes, M; Alarcón, J; Tello, A; Pérez-Donoso, J M

    2016-09-01

    Here we report the use of pigments produced by UV-resistant Antarctic bacteria as photosensitizers in Dye Sensitized Solar Cells (DSSCs). Pigments were obtained from red and yellow colored psychrotolerant bacteria isolated from soils of King George Island, Antarctica. Based on metabolic characteristics and 16s DNA sequence, pigmented bacteria were identified as Hymenobacter sp. (red) and Chryseobacterium sp. (yellow). Pigments produced by these microorganisms were extracted and classified as carotenoids based on their spectroscopic and structural characteristics, determined by UV-Vis spectrophotometry and infrared spectroscopy (FTIR), respectively. With the purpose of develop green solar cells based on bacterial pigments, the photostability and capacity of these molecules as light harvesters in DSSCs were determined. Absorbance decay assays determined that bacterial carotenoids present high photostability. In addition, solar cells based on these photosensitizers exhibit an open circuit voltage (VOC) of 435.0 [mV] and a short circuit current density (ISC) of 0.2 [mA·cm(-2)] for the red pigment, and a VOC of 548.8 [mV] and a ISC of 0.13 [mA·cm(-2)] for the yellow pigment. This work constitutes the first approximation of the use of pigments produced by non-photosynthetic bacteria as photosensitizers in DSSCs. Determined photochemical characteristics of bacterial pigments, summed to their easy obtention and low costs, validates its application as photosensitizers in next-generation biological solar cells. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Symmetrical and Unsymmetrical Fault Currents of a Wind Power Plant: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Gevorgian, V.; Singh, M.; Muljadi, E.

    2011-12-01

    This paper investigates the short-circuit behavior of a wind power plant for different types of wind turbines. Both symmetrical faults and unsymmetrical faults are investigated. The size of wind power plants (WPPs) keeps getting bigger and bigger. The number of wind plants in the U.S. has increased very rapidly in the past 10 years. It is projected that in the U.S., the total wind power generation will reach 330 GW by 2030. As the importance of WPPs increases, planning engi-neers must perform impact studies used to evaluate short-circuit current (SCC) contribution of the plant into the transmission network under different fault conditions. This information is needed to size the circuit breakers, to establish the proper sys-tem protection, and to choose the transient suppressor in the circuits within the WPP. This task can be challenging to protec-tion engineers due to the topology differences between different types of wind turbine generators (WTGs) and the conventional generating units. This paper investigates the short-circuit behavior of a WPP for different types of wind turbines. Both symmetrical faults and unsymmetrical faults are investigated. Three different soft-ware packages are utilized to develop this paper. Time domain simulations and steady-state calculations are used to perform the analysis.

  10. Impact of antibiotic resistance in the management of ocular infections: the role of current and future antibiotics

    Directory of Open Access Journals (Sweden)

    Joseph S Bertino Jr

    2009-09-01

    Full Text Available Joseph S Bertino Jr1,21College of Physicians and Surgeons, Columbia University, New York, N Y, USA; 2Principal, Bertino Consulting, Schenectady, NY, USAPurpose: This article reviews the effects of the increase in bacterial resistance on the treatment of ocular infections.Design: Interpretive assessment.Methods: Literature review and interpretation.Results: Ocular bacterial infections include conjunctivitis, keratitis, endophthalmitis, blepharitis, orbital cellulitis, and dacryocystitis. Treatment for most ocular bacterial infections is primarily empiric with broad-spectrum antibiotics, which are effective against the most common bacteria associated with these ocular infections. However, the widespread use of broad-spectrum systemic antibiotics has resulted in a global increase in resistance among both Gram-positive and Gram-negative bacteria to a number of the older antibiotics as well as some of the newer fluoroquinolones used to treat ophthalmic infections. Strategies for the prevention of the increase in ocular pathogen resistance should be developed and implemented. In addition, new antimicrobial agents with optimized pharmacokinetic and pharmacodynamic properties that have low toxicity, high efficacy, and reduced potential for the development of resistance are needed.Conclusions: New antimicrobial agents that treat ocular infections effectively and have a low potential for the development of resistance could be a part of strategies to prevent the global increase in ocular pathogen resistance.Keywords: ocular infections, emerging pathogen drug resistance, fluoroquinolones, besifloxacin

  11. Universal correlation between critical current density and normal-state resistivity in porous YBa2Cu3O7-x thin films

    International Nuclear Information System (INIS)

    Bartolome, E; Goemory, F; Granados, X; Puig, T; Obradors, X

    2007-01-01

    We have simulated the inductive critical currents and transport currents in the dissipative state of superconducting thin films with an increasing amount of porosity by using a Bean model-based programme (Trazacorrientes(registered) ) and finite-element software. Simulations allowed us to find a quantitative, quasi-universal relationship between the overall critical current density and the normal-state resistivity via the sample porosity. This theoretical curve served to fit the experimental data found for a large number (∼150) of epitaxial YBa 2 Cu 3 O 7-x thin films grown by the trifluoracetate route

  12. Mesoscopic current transport in two-dimensional materials with grain boundaries: Four-point probe resistance and Hall effect

    DEFF Research Database (Denmark)

    Lotz, Mikkel Rønne; Boll, Mads; Østerberg, Frederik Westergaard

    2016-01-01

    We have studied the behavior of micro four-point probe (M4PP) measurements on two-dimensional (2D) sheets composed of grains of varying size and grain boundary resistivity by Monte Carlo based finite element (FE) modelling. The 2D sheet of the FE model was constructed using Voronoi tessellation...... to emulate a polycrystalline sheet, and a square sample was cut from the tessellated surface. Four-point resistances and Hall effect signals were calculated for a probe placed in the center of the square sample as a function of grain density n and grain boundary resistivity ρGB. We find that the dual...... configuration sheet resistance as well as the resistance measured between opposing edges of the square sample have a simple unique dependency on the dimension-less parameter √nρGBG0, where G0 is the sheet conductance of a grain. The value of the ratio RA/RB between resistances measured in A- and B...

  13. Bacterial profile and patterns of antimicrobial drug resistance in intra-abdominal infections: Current experience in a teaching hospital

    Directory of Open Access Journals (Sweden)

    Neetu Shree

    2013-01-01

    Full Text Available Context: Bacterial isolates from intra-abdominal infections, in particular, peritonitis and their unpredictable antimicrobial resistance patterns, continue to be a matter of concern not only globally but regionally too. Aim: An attempt in the present study was made to study the patterns of drug resistance in bacterial isolates, especially gram negative bacilli in intra-abdominal infections (IAI in our hospital. Materials and Methods: From 100 cases of peritonitis, identification of isolates was done as per recommended methods. Antimicrobial susceptibility and extended-spectrum beta-lactamase (ESBL testing were performed following the CLSI guidelines. Results: A total of 133 clinical isolates were obtained, of which 108 were aerobes and 22 anaerobes. Fungal isolates were recovered in only three cases. Escherichia coli (47/108 emerged as the most predominant pathogen followed by Klebsiella spp. (27/108, while Bacteroides fragilis emerged as the predominant anaerobe (12/22. Among coliforms, 61.7% E. coli and 74.1% Klebsiella spp. were ESBL positive. A high level of resistance was observed for beta lactams, ciprofloxacin, amikacin, and ertapenem. Ertapenem resistance (30-41% seen in coliforms, appears as an important issue. Imipenem, tigecycline, and colistin were the most consistently active agents tested against ESBL producers. Conclusion: Drug resistance continues to be a major concern in isolates from intra-abdominal infections. Treatment with appropriate antibiotics preceded by antimicrobial resistance testing aided by early diagnosis, adequate surgical management, and knowledge of antibiotic - resistant organisms appears effective in reducing morbidity and mortality in IAI cases.

  14. Laboratory-based surveillance of current antimicrobial resistance patterns and trends among Staphylococcus aureus: 2005 status in the United States

    Directory of Open Access Journals (Sweden)

    Hogan Patricia

    2006-02-01

    Full Text Available Abstract Background The virulence, antimicrobial resistance, and prevalence of S. aureus underscores the need for up-to-date and extensive insights regarding antimicrobial susceptibility trends. One approach to meet this need is analysis of clinical laboratory – based surveillance data. Methods Data from The Surveillance Network-USA (TSN, an electronic surveillance network that collects microbiology data from 300 clinical microbiology laboratories across the United States, were used as the source for analysis that included prevalence of S. aureus in clinical specimens, MRSA and multi-drug resistance phenotype rates and trends according to patient location, geographic distributions, and specimen source. Results S. aureus was the most prevalent species isolated from inpatient specimens (18.7% of all bacterial isolates and the second most prevalent (14.7% from outpatient specimens. In March 2005 MRSA rates were 59.2%, 55%, and 47.9% for strains from non-ICU inpatients, ICU, and outpatients, respectively. This trend was noted in all nine US Bureau of Census regions and multi-drug resistance phenotypes (resistance to ≥ 3 non-beta-lactams was common among both inpatient MRSA (59.9% and outpatient MRSA (40.8%. Greater than 90% of multi-drug resistant MRSA were susceptible to trimethoprim-sulfamethoxazole, linezolid, and vancomycin. Conclusion Prevalence of MRSA among both inpatient and outpatient specimens continues to increase with multi-drug resistance as a common phenotype. Continued emergence of outpatient MRSA that exhibit multi-drug resistant phenotypes has important implications for developing and evolving outpatient treatment guidelines.

  15. Upgrade of the Gas Flow Control System of the Resistive Current Leads of the LHC Inner Triplet Magnets: Simulation and Experimental Validation

    CERN Document Server

    Perin, A; Casas-Cubillos, J; Pezzetti, M

    2014-01-01

    The 600 A and 120 A circuits of the inner triplet magnets of the Large Hadron Collider are powered by resistive gas cooled current leads. The current solution for controlling the gas flow of these leads has shown severe operability limitations. In order to allow a more precise and more reliable control of the cooling gas flow, new flowmeters will be installed during the first long shutdown of the LHC. Because of the high level of radiation in the area next to the current leads, the flowmeters will be installed in shielded areas located up to 50 m away from the current leads. The control valves being located next to the current leads, this configuration leads to long piping between the valves and the flowmeters. In order to determine its dynamic behaviour, the proposed system was simulated with a numerical model and validated with experimental measurements performed on a dedicated test bench.

  16. Capacitively coupled and direct-current resistivity surveys of selected reaches of Cozad, Thirty-Mile, Orchard-Alfalfa, Kearney, and Outlet Canals in Nebraska, 2012-13

    Science.gov (United States)

    Hobza, Christopher M.; Burton, Bethany L.; Lucius, Jeffrey E.; Tompkins, Ryan E.

    2014-01-01

    Understanding the spatial characteristics of leakage from canals is critical to effectively managing and utilizing water resources for irrigation and hydroelectric purposes. Canal leakage in some parts of Nebraska is the primary source of water for groundwater recharge and helps maintain the base flow of streams. Because surface-water supplies depend on the streamflow of the Platte River and the available water stored in upstream reservoirs, water managers seek to minimize conveyance losses, which can include canal leakage. The U.S. Geological Survey, in cooperation with the Central Platte Natural Resources District and Nebraska Public Power District, used capacitively coupled (CC) and direct-current (DC) resistivity techniques for continuous resistivity profiling to map near-surface lithologies near and underlying the Cozad, Thirty-Mile, Orchard-Alfalfa, Kearney, and Outlet Canals. Approximately 84 kilometers (km) of CC-resistivity data were collected along the five canals. The CC-resistivity data were compared with results from continuous sediment cores and electrical conductivity logs. Generally, the highest resistivities were recorded at the upstream reaches of the Cozad, Thirty-Mile, and Orchard-Alfalfa canals where flood-plain deposits of silt and clay mantle coarser channel deposits of sand and gravel. The finer grained deposits gradually thicken with increasing distance away from the Platte River. Consequently, for many surveyed reaches the thickness of fine-grained deposits exceeded the 8-meter depth of investigation. A detailed geophysical investigation along a 5-km reach of the Outlet Canal southwest of North Platte, Nebraska, used CC and DC resistivity to examine the condition of a compacted-core bank structure and characterized other potential controls on areas of focused seepage. CC-resistivity data, collected along the 5-km study reach, were compared with continuous sediment cores and DC-resistivity data collected near a selected seep near Outlet

  17. High prevalence of antibiotic-resistant Mycoplasma genitalium in nongonococcal urethritis: the need for routine testing and the inadequacy of current treatment options.

    Science.gov (United States)

    Pond, Marcus J; Nori, Achyuta V; Witney, Adam A; Lopeman, Rose C; Butcher, Philip D; Sadiq, Syed Tariq

    2014-03-01

     Empirical antibiotic therapy for nongonococcal urethritis (NGU) and cervicitis is aimed at Chlamydia trachomatis, but Mycoplasma genitalium, which also commonly causes undiagnosed NGU, necessitates treatment with macrolides or fluoroquinolones rather than doxycycline, the preferred chlamydia treatment. Prevalence of M. genitalium and associated genotypic markers of macrolide and fluoroquinolone resistance among men symptomatic of urethritis were investigated. Genetic diversity of M. genitalium populations was determined to infer whether findings were applicable beyond our setting.  Mycoplasma genitalium and other NGU pathogens were detected using nucleic acid amplification methods, and DNA sequencing was used to detect genotypic resistance markers of macrolide and fluoroquinolone antibiotics in 23S ribosomal RNA, gyrA, gyrB, and parC genes. MG191 single-nucleotide polymorphism typing and MG309 variable number tandem analysis were combined to assign a dual locus sequence type (DLST) to each positive sample.  Among 217 men, M. genitalium prevalence was 16.7% (95% confidence interval [CI], 9.5%-24.0%) and C. trachomatis prevalence was 14.7% (95% CI, 7.8%-21.6%) in NGU cases. Nine of 22 (41%; 95% CI, 20%-62%) patients with M. genitalium were infected with DLSTs possessing genotypic macrolide resistance and 1 patient was infected with a DLST having genotypic fluoroquinolone resistance. Typing assigned M. genitalium DLSTs to 2 major clusters, broadly distributed among previously typed international strains. Genotypic macrolide resistance was spread within these 2 clusters.  Mycoplasma genitalium is a frequent undiagnosed cause of NGU in this population with rates of macrolide resistance higher than those previously documented. Current guidelines for routine testing and empirical treatment of NGU should be modified to reduce treatment failure of NGU and the development of further resistance.

  18. Virtual Resistance-Based Control Strategy for DC link Regeneration Protection and Current Sharing in Uninterruptible Power Supply

    DEFF Research Database (Denmark)

    Lu, Jinghang; Guan, Yajuan; Savaghebi, Mehdi

    2017-01-01

    To address the DC link voltage regeneration issue in parallel Uninterruptible Power Supply (UPS) system, a DC link voltage protection (DCVP) method through online virtual resistance regulation is proposed. The proposed control strategy is able to protect the DC link from overvoltage that may...

  19. A new artificial diet for western corn rootworm larvae is compatible with and detects resistance to all current Bt toxins

    Science.gov (United States)

    Insect resistance to transgenic crops expressing one or more genes from Bacillus thuringiensis Berliner (Bt) is a growing concern for farmers, regulatory agencies, the seed industry, and researchers alike. Western corn rootworm (Diabrotica virgifera virgifera LeConte) is a pest of corn (Zea mays L.)...

  20. Changing epidemiology of methicillin-resistant Staphylococcus aureus in Iceland from 2000 to 2008: a challenge to current guidelines

    DEFF Research Database (Denmark)

    Holzknecht, B.J.; Hardardottir, H.; Haraldsson, Gustav Helgi

    2010-01-01

    The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) is continuously changing. Iceland has a low incidence of MRSA. A "search and destroy" policy (screening patients with defined risk factors and attempting eradication in carriers) has been implemented since 1991. Clinical...

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

    Directory of Open Access Journals (Sweden)

    Juravleov A.

    2008-12-01

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

  2. Effect of Welding Current on the Structure and Properties of Resistance Spot Welded Dissimilar (Austenitic Stainless Steel and Low Carbon Steel) Metal Joints

    Science.gov (United States)

    Shawon, M. R. A.; Gulshan, F.; Kurny, A. S. W.

    2015-04-01

    1.5 mm thick sheet metal coupons of austenitic stainless steel and plain low carbon steel were welded by resistance spot welding technique. The effects of welding current in the range 3-9 kA on the structure and mechanical properties of welded joint were investigated. The structure was studied by macroscopic, microscopic and scanning electron microscopy techniques. Mechanical properties were determined by tensile testing and microhardness measurements. Asymmetrical shape weld nugget was found to have formed in the welded joint which increased in size with an increase in welding current. The fusion zone showed cast structure with coarse columnar grain and dendritic with excess delta ferrite in austenitic matrix. Microhardness of the weld nugget was maximum because of martensite formation. An increase in welding current also increased tensile strength of the weld coupon. An attempt has also been made to relate the mode of fracture with the welding current.

  3. Infection control, genetic assessment of drug resistance and drug susceptibility testing in the current management of multidrug/extensively-resistant tuberculosis (M/XDR-TB) in Europe

    DEFF Research Database (Denmark)

    Bothamley, Graham H.; Lange, Christoph; Albrecht, Dirk

    2017-01-01

    AIM: Europe has the highest documented caseload and greatest increase in multidrug and extensively drug-resistant tuberculosis (M/XDR-TB) of all World Health Organization (WHO) regions. This survey examines how recommendations for M/XDR-TB management are being implemented. METHODS: TBNET is a pan......-European clinical research collaboration for tuberculosis. An email survey of TBNET members collected data in relation to infection control, access to molecular tests and basic microbiology with drug sensitivity testing. RESULTS: 68/105 responses gave valid information and were from countries within the WHO...... widely available (88%), even in lower income and especially in high incidence countries. Molecular tests for other first line and second line drugs were less accessible (76 and 52% respectively). A third of physicians considered that drug susceptibility results were delayed by > 2 months. CONCLUSION...

  4. RESULTS OF CALCULATION-EXPERIMENTAL INVESTIGATIONS OF ELECTRO-THERMAL RESISTIBILITY OF SHEET STEEL SAMPLES TO ACTION OF RATIONED COMPONENTS OF PULSED CURRENT OF ARTIFICIAL LIGHTING

    Directory of Open Access Journals (Sweden)

    M.I. Baranov

    2016-06-01

    Full Text Available Purpose. Calculation and experimental researches of the electro-thermal resistibility of the steel sheet samples to action standard pulse current components of the artificial lightning with amplitude-time parameters (ATP, corresponded the requirements of normative documents of USA for SAE ARP 5412 & SAE ARP 5416. Methodology. Electrophysics bases of technique of high tensions and large impulsive currents (LIC, and also scientific and technical bases of planning of devices of high-voltage impulsive technique and measuring in them LIC. Сurrent amplitude ImA=±200 kA (with a tolerance of ±10 %; current action integral JA=2∙106 A2•s (with a tolerance of ±20 %; time, corresponding to the amplitude of the current ImA, tmA≤50 microseconds; the duration of the current flow τpA≤500 microseconds. Results. The results of the evaluation of the calculated and experimental studies of electro-thermal resistance of the samples of plates measuring 0,5 m  0,5 m stainless steel 1 mm thickness to the action on them artificial lightning impulse currents with rationed ATP on the requirements of normative documents of USA for SAE ARP 5412 & SAE ARP 5416. A pulse A- component have a first amplitude 192 kA, the corresponding time of 34 μs, and the duration aperiodic component amplitude 804 A, corresponding to the time 9 ms. It has been shown that the long C- component current of artificial lightning can lead to keyhole these samples. The diameter of the holes in this thin steel sheet, which is formed during the flow of current C- components can reach 15 mm. The results of calculation and experiment agree within 28 %. Originality. For the first time in world practice on the generator large pulsed currents experimental studies of resistibility of sheet steel samples to the action of artificial lightning currents with critical parameters. Practical value. Using the results obtained in the practice of lightning protection will significantly improve the

  5. Recovery Characteristics of GdBCO Superconducting Tape With Cooling Fins and Teflon Coating for Resistive Fault Current Limiter

    OpenAIRE

    Shirai, Yasuyuki; Yoneda, Kazuya; Higa, Daisuke; Shiotsu, Masahiro; Honda, Yoshihiro; Isojima, Shigeki

    2016-01-01

    Recovery time, which is defined as the time during which the superconducting component recovers to its initial condition after the current-limiting operation, is very important to design an SFCL. In this paper, the cooling properties of GdBCO superconducting tape with various types of fins or PTFE (polytetrafluoroethylene:Teflon) coating were investigated. Superconducting tape was heated by current, which was larger than its critical current, in liquid nitrogen. The cooling down speed after t...

  6. Characteristics of contact resistance for Ag, Cu and Al spot contact under DC current flow of 300A; Gin, do oyobi arumi tensesshokushi no chokuryu 300A tsudenji ni okeru sesshoku teiko tokusei

    Energy Technology Data Exchange (ETDEWEB)

    Aichi, H. [Daido Institute of Technology, Nagoya (Japan); Matsumura, T. [Nagoya University, Nagoya (Japan); Miyachi, I. [Aichi Inst. of Technology, Aichi (Japan)

    1997-07-01

    The temperature rise of the contact spot by Joule`s heat under high current flow may result in the softening or welding of the contact materials. Contact resistances of Ag, Cu and Al spot contacts have been observed under the current flow of up to 300A DC. The contact resistances of Ag and Cu with clean surfaces were revealed to be kept constant independent of the magnitude of the applied current flow. On the other hand, contact resistances of Al and Cu with oxidized surfaces were greatly reduced with the increasing current flow. 7 refs., 5 figs., 2 tabs.

  7. Final report on RMO comparison SIM.EM-S10: High value resistance comparison with two-terminal cryogenic current comparators

    Science.gov (United States)

    Bierzychudek, Marcos E.; Elmquist, Randolph; Hernández, Felipe

    2014-01-01

    This work presents a supplementary comparison of high value resistance standards performed during 2012 and January 2013, following the guidelines presented in a document about measurement comparisons in the CIPM MRA. The purpose of this task was to compare the high resistance cryogenic current comparator scaling of the participating institutes: National Institute of Standards and Technology, USA (NIST), Centro Nacional de Metrología, Mexico (CENAM) and Instituto Nacional de Tecnología Industrial, Argentina (INTI), all of which are members of the Sistema Interamericano de Metrología (SIM) Regional Metrology Organization. All the measurements of this comparison were performed with two-terminal cryogenic current comparators (CCC). Degrees of equivalence of the participating institutes relative to the comparison reference values are given in the report for the measured resistance values. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by SIM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

  8. Changing epidemiology of methicillin-resistant Staphylococcus aureus in Iceland from 2000 to 2008: a challenge to current guidelines

    DEFF Research Database (Denmark)

    Holzknecht, B.J.; Hardardottir, H.; Haraldsson, Gustav Helgi

    2010-01-01

    The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) is continuously changing. Iceland has a low incidence of MRSA. A "search and destroy" policy (screening patients with defined risk factors and attempting eradication in carriers) has been implemented since 1991. Clinical...... and microbiological data of all MRSA patients from the years 2000 to 2008 were collected prospectively. Isolates were characterized by pulsed-field gel electrophoresis (PFGE), sequencing of the repeat region of the Staphylococcus protein A gene (spa typing), staphylococcal cassette chromosome mec (SCCmec) typing...

  9. Measuring ac losses in superconducting cables using a resonant circuit:Resonant current experiment (RESCUE)

    DEFF Research Database (Denmark)

    Däumling, Manfred; Olsen, Søren Krüger; Rasmussen, Carsten

    1998-01-01

    A simple way to obtain true ac losses with a resonant circuit containing a superconductor, using the decay of the circuit current, is described. For the measurement a capacitor is short circuited with a superconducting cable. Energy in the circuit is provided by either charging up the capacitors...... be recorded using, for example, a digital oscilloscope. The amplitude decay of the periodic voltage or current accurately reflects the power loss in the system. It consists of two components-an ohmic purely exponential one (from leads, contacts, etc.), and a nonexponential component originating from...

  10. Detection of mechanical failures in induction motors by current spectrum analysis

    Energy Technology Data Exchange (ETDEWEB)

    Sokansky, K.; Novak, P.; Bilos, J.; Labaj, J. [Technical University Ostrava, Moraviasilesian Power Stations s.h.c. (Czech Republic)

    1997-12-31

    From the diagnostic point of view, an electric machine can be understood as an electromechanical system. It means that any manifestations of mechanical failures do not have to show themselves only in mechanical quantities, i.e. vibration in our case. Mechanical failures can also manifest themselves in electrical quantities, namely in electric current in our case. This statement is valid inversely too, which means that faults occurring in electric circuits can be measured through mechanical quantities. This presentation deals with measuring the current spectra of induction motors with short circuited armatures that are drives used in the industries most. (orig.) 3 refs.

  11. Voltage and oxide thickness dependent tunneling current density and tunnel resistivity model: Application to high-k material HfO2 based MOS devices

    Science.gov (United States)

    Maity, N. P.; Maity, Reshmi; Baishya, Srimanta

    2017-11-01

    In this paper presents a straightforward efficient investigation of tunneling current density for ultra thin oxide layer based metal-oxide-semiconductor (MOS) devices to realization the gate current as a function of applied potential and oxide thickness. Solutions to the Schrödinger's wave equation are evolved for the different potential energy regions of the MOS device considering appropriate effective mass for each region. For finding approximate mathematical solutions to linear differential equations using spatially changeable coefficients the Wentzel-Kramers-Brillouin (WKB) approximation technique is considered. A p-substrate based n-channel MOS device has been analyzed consisting of SiO2 material as the oxide dielectric along with high-k material HfO2. The tunnel resistivity is correspondingly assessed employing this tunneling current density model. Synopsys Technology Computer Aided Design (TCAD) tool results are employed to validate the analytical model. Tremendous agreements among the results are observed.

  12. Multiple negative differential resistance devices with ultra-high peak-to-valley current ratio for practical multi-valued logic and memory applications

    Science.gov (United States)

    Shin, Sunhae; Rok Kim, Kyung

    2015-06-01

    In this paper, we propose a novel multiple negative differential resistance (NDR) device with ultra-high peak-to-valley current ratio (PVCR) over 106 by combining tunnel diode with a conventional MOSFET, which suppresses the valley current with transistor off-leakage level. Band-to-band tunneling (BTBT) in tunnel junction provides the first peak, and the second peak and valley are generated from the suppression of diffusion current in tunnel diode by the off-state MOSFET. The multiple NDR curves can be controlled by doping concentration of tunnel junction and the threshold voltage of MOSFET. By using complementary multiple NDR devices, five-state memory is demonstrated only with six transistors.

  13. Mitigating the Impact of Antibacterial Drug Resistance through Host-Directed Therapies: Current Progress, Outlook, and Challenges

    Directory of Open Access Journals (Sweden)

    Chih-Yuan Chiang

    2018-01-01

    Full Text Available Increasing incidences of multidrug resistance in pathogenic bacteria threaten our ability to treat and manage bacterial infection. The development and FDA approval of novel antibiotics have slowed over the past decade; therefore, the adoption and improvement of alternative therapeutic strategies are critical for addressing the threat posed by multidrug-resistant bacteria. Host-directed therapies utilize small-molecule drugs and proteins to alter the host response to pathogen infection. Here, we highlight strategies for modulating the host inflammatory response to enhance bacterial clearance, small-molecule potentiation of innate immunity, and targeting of host factors that are exploited by pathogen virulence factors. Application of state-of-the-art “omic” technologies, including proteomics, transcriptomics, and image-omics (image-based high-throughput phenotypic screening, combined with powerful bioinformatics tools will enable the modeling of key signaling pathways in the host-pathogen interplay and aid in the identification of host proteins for therapeutic targeting and the discovery of host-directed small molecules that will regulate bacterial infection. We conclude with an outlook on research needed to overcome the challenges associated with transitioning host-directed therapies into a clinical setting.

  14. Measurement and Modeling of Lateral Subsurface Transient Soil Moisture Dynamics Using Multi-Point Direct-Current Resistivity in Homogeneous Sand

    Science.gov (United States)

    Franz, T. E.; Nolan, J. T.; Caylor, K. K.; Nordbotten, J. M.; Slater, L. D.

    2010-12-01

    Direct measurements of soil moisture are extremely difficult to obtain between the spatial scales of point measurements and remote sensing. Nevertheless, the spatiotemporal distribution of soil moisture remains a key variable in ecohydrology. Recent ecological evidence has linked the spatial patterns of termite nests with increases in plant productivity and trophic-level responses. In an idealized laboratory setting, we explore the use of multi-point direct-current resistivity to examine spatiotemporal changes in soil moisture following a rapid infiltration event into a large macropore. The methodology was selected because the timescale of flow processes in the homogeneous isotropic sand prevented the use of imaging techniques. Selection of an appropriate electrode array was critical for collecting the required high-resolution spatiotemporal resistivity measurements. Direct placement of a dense array of electrodes in the sand allowed us to use geostatistical methods for spatial interpolation, thereby removing the inherent uncertainty resulting from inversion mechanics. Instead, conversion of resistivity to saturation was directly performed using Archie’s Law given the simplified material properties of the system. We compared the observations to a 2-dimensional axisymmetric numerical solution of the system, using the HYDRUS 2D/3D software, and to a semi-analytical solution in order to estimate soil hydraulic properties. We found satisfactory comparisons between the observations, numerical, and semi-analytical solutions of the system, which indicates that this technique may be applicable for field scale settings. While the use of Archie’s Law may only be appropriate in idealized laboratory settings, the rapid measurements and localized support volumes of multi-point direct-current resistivity methods has the potential to provide an invaluable constraint for joint or coupled geophysical surveys in more complex field settings.

  15. Shunt resistance and saturation current determination in CdTe and CIGS solar cells. Part 1: a new theoretical procedure and comparison with other methodologies

    Science.gov (United States)

    Rangel-Kuoppa, Victor-Tapio; Albor-Aguilera, María-de-Lourdes; Hérnandez-Vásquez, César; Flores-Márquez, José-Manuel; González-Trujillo, Miguel-Ángel; Contreras-Puente, Gerardo-Silverio

    2018-04-01

    A new proposal for the extraction of the shunt resistance (R sh ) and saturation current (I sat ) of a current-voltage (I-V) measurement of a solar cell, within the one-diode model, is given. First, the Cheung method is extended to obtain the series resistance (R s ), the ideality factor (n) and an upper limit for I sat . In this article which is Part 1 of two parts, two procedures are proposed to obtain fitting values for R sh and I sat within some voltage range. These two procedures are used in two simulated I-V curves (one in darkness and the other one under illumination) to recover the known solar cell parameters R sh , R s , n, I sat and the light current I lig and test its accuracy. The method is compared with two different common parameter extraction methods. These three procedures are used and compared in Part 2 in the I-V curves of CdS-CdTe and CIGS-CdS solar cells.

  16. Changing epidemiology of methicillin-resistant Staphylococcus aureus in Iceland from 2000 to 2008: a challenge to current guidelines

    DEFF Research Database (Denmark)

    Holzknecht, B.J.; Hardardottir, H.; Haraldsson, Gustav Helgi

    2010-01-01

    The epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) is continuously changing. Iceland has a low incidence of MRSA. A "search and destroy" policy (screening patients with defined risk factors and attempting eradication in carriers) has been implemented since 1991. Clinical...... and microbiological data of all MRSA patients from the years 2000 to 2008 were collected prospectively. Isolates were characterized by pulsed-field gel electrophoresis (PFGE), sequencing of the repeat region of the Staphylococcus protein A gene (spa typing), staphylococcal cassette chromosome mec (SCCmec) typing......, and screening for the Panton-Valentine leukocidin (PVL) gene. Two hundred twenty-six infected (60%) or colonized (40%) individuals were detected (annual incidence 2.5 to 16/100,000). From 2000 to 2003, two health care-associated outbreaks dominated (spa types t037 and t2802), which were successfully controlled...

  17. No Good Wars: Teaching the History of Modern American Wars as a Means of Resisting Current Ones

    Science.gov (United States)

    Long, Kenneth

    2008-01-01

    In the fall 2005 semester, the author designed a course in the history of America's modern wars hoping to encourage students to criticize and oppose the country's current aggressions in Afghanistan and Iraq. Surveys of student attitude change suggest that the course did promote criticism but did far less to facilitate student activism. The author…

  18. A Procedure to Determine and Correct for Transmission Line Resistances for Direct Current On-Wafer Measurements

    Science.gov (United States)

    2010-05-01

    device, such as a bipolar junction transistor ( BJT ), a metal oxide semiconductor field effect transistor (MOSFET), or a high electron mobility...VDS_mesh,IDS,[0:.05:.5],’:’); 12 List of Symbols, Abbreviations, and Acronyms BJT bipolar junction transistor DC direct current DUT device... transistor (HEMT), when measured on-wafer, may be measured using two separate power lines with ground-signal-ground (GSG) on-wafer probes. Each power

  19. Temporal analysis of Z-Gradient coil eddy currents in tungsten collimator with different resistivities for SPECT/MRI

    Energy Technology Data Exchange (ETDEWEB)

    Samoudi, Amine [INTEC, Ghent University/iMinds, Ghent (Belgium); Van Audenhaege, Karen [ELIS, Ghent University/iMinds, Ghent (Belgium); Vermeeren, Günter [INTEC, Ghent University/iMinds, Ghent (Belgium); Poole, Micahel [INM-4, Forschungszentrum Jülich GmbH, Jülich (Germany); Martens, Luc [INTEC, Ghent University/iMinds, Ghent (Belgium); Van Holen, Roel [ELIS, Ghent University/iMinds, Ghent (Belgium); Joseph, Wout [INTEC, Ghent University/iMinds, Ghent (Belgium)

    2014-07-29

    Combining Single Photon Emission Computed Tomography (SPECT) with Magnetic Resonance Imaging (MRI) results in an interaction of the time-varying magnetic field gradients with the highly conducting tungsten collimator, which generates a secondary magnetic field causing spatial distortions in reconstructed MR images. Accurate simulations are important for the characterization of these eddy currents and to further optimize the gradient coils and the collimator design.

  20. Thermal contact resistance measurement of conduction cooled binary current lead joint block in cryocooler based self field I-V characterization facility

    Energy Technology Data Exchange (ETDEWEB)

    Kundu, Ananya, E-mail: ananya@ipr.res.in; Das, Subrat Kumar; Agarwal, Anees Bano Pooja; Pradhan, Subrata [Institute for Plasma Research, Bhat, Gandhinagar, Gujarat 382428 (India)

    2016-05-23

    In the present study thermal resistance of conduction cooled current lead joint block employing two different interfacial material namely AlN sheet and Kapton Film have been studied in the temperature range 5K-35K. In each case, the performance of different interlayer materials e.g. Indium foil for moderately pressurized contacts (contact pressure <1 MPa), and Apiezon N Grease, GE varnish for low pressurized contact (contact pressure <1 MPa) is studied. The performances of AlN joint with Indium foil and with Apeizon N Grease are studied and it is observed that the contact resistance reduces more with indium foil as compared to greased contact. The contact resistance measurements of Kapton film with Apiezon N grease and with GE varnish were also carried out in the same temperature range. A comparative study of AlN joint with Indium foil and Kapton with GE varnish as filler material is carried out to demonstrate better candidate material among Kapton and AlN for a particular filler material in the same temperature range.

  1. Use of cyclic current reversal polarization voltammetry for investigating the relationship between corrosion resistance and heat-treatment induced variations in microstructures of 400 C martensitic stainless steels

    Science.gov (United States)

    Ambrose, John R.

    1992-01-01

    Software for running a cyclic current reversal polarization voltammagram has been developed for use with a EG&G Princeton Applied Research Model 273 potentiostat/galvanostat system. The program, which controls the magnitude, direction and duration of an impressed galvanostatic current, will produce data in ASCII spreadsheets (Lotus, Quattro) for graphical representation of CCRPV voltammograms. The program was used to determine differences in corrosion resistance of 440 C martenstic stainless steel produced as a result of changes in microstructure effected by tempering. It was determined that tempering at all temperatures above 400 F resulted in increased polarizability of the material, with the increased likelihood that pitting would be initiated upon exposure to marine environments. These results will be used in development of remedial procedures for lowering the susceptibility of these alloys toward the stress corrosion cracking experienced in bearings used in high pressure oxygen turbopumps used in the main engines of space shuttle orbiters.

  2. Realization of Current Mode Universal Filter and a Dual-Mode Single Resistance Controlled Quadrature Oscillator Employing VDCC and Only Grounded Passive Elements

    Directory of Open Access Journals (Sweden)

    Manish Gupta

    2017-01-01

    Full Text Available The manuscript presents a circuit that can act as a universal filter as well as a single resistence controlled oscillator by unpretentiously changing the switch positions. The circuit employs only two active devices and all grounded passive elements. The utilization of only grounded passive components makes this circuit a better choice for integrated circuit implementation. The current mode biquadratic filter offers all the five basic responses along with independent tunability of its quality factor. The dual-mode quadrature sinusoidal oscillator offers explicit current outputs along with voltage outputs. The circuit also offers a simple and uncoupled condition of oscillation and frequency of oscillation. The typical analysis such as non-ideal, sensitivity and parasitic analysis along with the regular simulation results as well as experimental results are exposed here, to strengthen the design idea.

  3. Current Situation of Antimicrobial Resistance and Genetic Differences in Stenotrophomonas maltophilia Complex Isolates by Multilocus Variable Number of Tandem Repeat Analysis.

    Science.gov (United States)

    Rhee, Ji Young; Song, Jae Hoon; Ko, Kwan Soo

    2016-12-01

    Stenotrophomonas maltophilia is one of several opportunistic pathogens of growing significance. Several studies on the molecular epidemiology of S. maltophilia have shown clinical isolates to be genetically diverse. A total of 121 clinical isolates tentatively identified as S. malophilia from seven tertiary-care hospitals in Korea from 2007 to 2011 were included. Species and groups were identified using partial gyrB gene sequences and antimicrobial susceptibility testing was performed using a broth microdilution method. Multi locus variable number of tandem repeat analysis (MLVA) surveys are used for subtyping. Based on partial gyrB gene sequences, 118 isolates were identified as belonging to the S. maltophilia complex. For all S. maltophilia isolates, the resistance rates to trimethoprime-sulfamethoxazole (TMP/SMX) and levofloxacin were the highest (both, 30.5%). Resistance rate to ceftazidime was 28.0%. 11.0% and 11.9% of 118 S. maltophilia isolates displayed resistance to piperacillin/tazobactam and tigecycline, respectively. Clade 1 and Clade 2 were definitely distinguished from the data of MLVA with amplification of loci. All 118 isolates were classified into several clusters as its identification. Because of high resistance rates to TMP/SMX and levofloxacin, the clinical laboratory department should consider providing the data about other antimicrobial agents and treatment of S. maltophilia infections with a combination of antimicrobials can be considered in the current practice. The MLVA evaluated in this study provides a fast, portable, relatively low cost genotyping method that can be employed in genotypic linkage or transmission networks comparing to analysis of the gyrB gene.

  4. Shunt resistance and saturation current determination in CdTe and CIGS solar cells. Part 2: application to experimental IV measurements and comparison with other methods

    Science.gov (United States)

    Rangel-Kuoppa, Victor-Tapio; Albor-Aguilera, María-de-Lourdes; Hérnandez-Vásquez, César; Flores-Márquez, José-Manuel; Jiménez-Olarte, Daniel; Sastré-Hernández, Jorge; González-Trujillo, Miguel-Ángel; Contreras-Puente, Gerardo-Silverio

    2018-04-01

    In this Part 2 of this series of articles, the procedure proposed in Part 1, namely a new parameter extraction technique of the shunt resistance (R sh ) and saturation current (I sat ) of a current-voltage (I-V) measurement of a solar cell, within the one-diode model, is applied to CdS-CdTe and CIGS-CdS solar cells. First, the Cheung method is used to obtain the series resistance (R s ) and the ideality factor n. Afterwards, procedures A and B proposed in Part 1 are used to obtain R sh and I sat . The procedure is compared with two other commonly used procedures. Better accuracy on the simulated I-V curves used with the parameters extracted by our method is obtained. Also, the integral percentage errors from the simulated I-V curves using the method proposed in this study are one order of magnitude smaller compared with the integral percentage errors using the other two methods.

  5. Dember and photo-electromotive-force currents in silicon photoconductive detectors

    Science.gov (United States)

    Dikmelik, Yamaç; Davidson, Frederic M.

    2004-09-01

    Dember and photo-electromotive-force (PEMF) currents are investigated in silicon photoconductive detectors both theoretically and experimentally. Dember photocurrents were found to dominate the response of high-purity silicon samples with top-surface electrodes to a moving interference pattern. The use of surface electrodes leads to shadowed regions beneath the electrodes, and Dember photocurrents appear under short-circuit conditions. A single-charge-carrier model of the Dember effect is in good qualitative agreement with experimental results. We also show theoretically that the PEMF effect in silicon is weak compared with other semiconductors because of its relatively high intrinsic conductivity.

  6. Internal Short Circuits in Lithium-Ion Cells for PHEVs

    Energy Technology Data Exchange (ETDEWEB)

    Sriramulu, Suresh [Tiax LLC, Lexington, MA (United States); Stringfellow, Richard [Tiax LLC, Lexington, MA (United States)

    2013-05-25

    Development of Plug-in Hybrid Electric Vehicles (PHEVs) has recently become a high national priority because of their potential to enable significantly reduced petroleum consumption by the domestic transportation sector in the relatively near term. Lithium-ion (Li-ion) batteries are a critical enabling technology for PHEVs. Among battery technologies with suitable operating characteristics for use in vehicles, Li-ion batteries offer the best combination of energy, power, life and cost. Consequently, worldwide, leading corporations and government agencies are supporting the development of Li-ion batteries for PHEVs, as well as the full spectrum of vehicular applications ranging from mild hybrid to all-electric. In this project, using a combination of well-defined experiments, custom designed cells and simulations, we have improved the understanding of the process by which a Li-ion cell that develops an internal short progresses to thermal runaway. Using a validated model for thermal runaway, we have explored the influence of environmental factors and cell design on the propensity for thermal runaway in full-sized PHEV cells. We have also gained important perspectives about internal short development and progression; specifically that initial internal shorts may be augmented by secondary shorts related to separator melting. Even though the nature of these shorts is very stochastic, we have shown the critical and insufficiently appreciated role of heat transfer in influencing whether a developing internal short results in a thermal runaway. This work should lead to enhanced perspectives on separator design, the role of active materials and especially cathode materials with respect to safety and the design of automotive cooling systems to enhance battery safety in PHEVs.

  7. Proposed budget cuts threaten to short-circuit Grid network

    CERN Multimedia

    Butler, D

    2001-01-01

    Changes to the budget for the European sixth Framework programme may jeapardize the Grid project. The EU Parliament have asked to cut the budget for infrastructure to 500 million euros from 900 and of this 150 million will probably be allocated to Ge the pan-European research network (1 page).

  8. Capacitive effects in IGBTs limiting their reliability under short circuit

    DEFF Research Database (Denmark)

    Reigosa, Paula Diaz; Iannuzzo, Francesco; Rahimo, Munaf

    2017-01-01

    , revealing that the gate capacitance changes according with the shape of the electric field due to the charge distribution in the n-base. It has been identified that the time-varying capacitance leads to parametric oscillations together with the stray gate inductance, which limit the reliability of the IGBT....

  9. Study on current limiting characteristics of SFCL with two trigger current levels

    International Nuclear Information System (INIS)

    Lim, S.H.

    2010-01-01

    In this paper, the superconducting fault current limiter (SFCL) with two trigger current levels was suggested and its effectiveness through the analysis on the current limiting characteristics was described. The proposed SFCL, which consists of the triggering and the limiting components, can limit the fault current by generating the limiting impedance through two steps according to the amplitude of the initial fault current. In case that the fault happens, the lower initial fault current causes the only superconducting element of the triggering component to be quenched. On the other hand, the higher initial fault current makes both the superconducting elements comprising the triggering and the limiting components of the SFCL to be quenched, which contributes to the higher impedance of the SFCL. Therefore, the effective fault current limiting operation of the SFCL can be performed by generating the SFCL's impedance in proportion to the amplitude of the initial fault current. To confirm the current limiting operation of the proposed SFCL, the short-circuit tests of the SFCL according to the fault angle were carried out and its effective fault current limiting operations could be discussed.

  10. Effect of Welding Current and Time on the Microstructure, Mechanical Characterizations, and Fracture Studies of Resistance Spot Welding Joints of AISI 316L Austenitic Stainless Steel

    Science.gov (United States)

    Kianersi, Danial; Mostafaei, Amir; Mohammadi, Javad

    2014-09-01

    This article aims at investigating the effect of welding parameters, namely, welding current and welding time, on resistance spot welding (RSW) of the AISI 316L austenitic stainless steel sheets. The influence of welding current and welding time on the weld properties including the weld nugget diameter or fusion zone, tensile-shear load-bearing capacity of welded materials, failure modes, energy absorption, and microstructure of welded nuggets was precisely considered. Microstructural studies and mechanical properties showed that the region between interfacial to pullout mode transition and expulsion limit is defined as the optimum welding condition. Electron microscopic studies indicated different types of delta ferrite in welded nuggets including skeletal, acicular, and lathy delta ferrite morphologies as a result of nonequilibrium phases, which can be attributed to a fast cooling rate in the RSW process. These morphologies were explained based on Shaeffler, WRC-1992, and pseudo-binary phase diagrams. The optimum microstructure and mechanical properties were achieved with 8-kA welding current and 4-cycle welding time in which maximum tensile-shear load-bearing capacity or peak load of the welded materials was obtained at 8070 N, and the failure mode took place as button pullout with tearing from the base metal. Finally, fracture surface studies indicated that elongated dimples appeared on the surface as a result of ductile fracture in the sample welded in the optimum welding condition.

  11. Proposal for the Award of a Contract for the Supply of 60A Resistive Current Lead Assemblies for the LHC Dipole Corrector Magnets

    CERN Document Server

    2002-01-01

    This document concerns the award of a contract for the supply of 360 resistive current lead assemblies for the LHC dipole corrector magnets. Following a market survey carried out among 54 firms in twelve Member States, a call for tenders (IT-2901/LHC/LHC) was sent on 11 July 2002 to six firms in three Member States. By the closing date, CERN had received four tenders from four firms in three Member States. The Finance Committee is invited to agree to the negotiation of a contract with MARK & WEDELL (DK), the lowest bidder, for the supply of 360 current lead assemblies, for a total amount of 1 508 123 Swiss francs, not subject to revision, with options for up to 50 additional current lead assemblies, including 50 sets of related components for an additional amount of 198 997 Swiss francs, not subject to revision, bringing the total amount to 1 707 120 Swiss francs, not subject to revision. The firm has indicated the following distribution by country of the contract value covered by this adjudication propos...

  12. A No-Arc DC Circuit Breaker Based on Zero-Current Interruption

    Science.gov (United States)

    Xiang, Xuewei; Chai, Jianyun; Sun, Xudong

    2017-05-01

    A dc system has no natural current zero-crossing point, so a dc arc is more difficult to extinguish than an ac arc. In order to effectively solve the problem of the dc arc, this paper proposes a dc circuit breaker (DCCB) capable of implementing a no-arc interruption. The proposed DCCB includes a main branch consisting of a mechanical switch, a diode and a current-limiting inductor, a semi-period resonance circuit consisting of a diode, an inductor and a capacitor, and a buffer branch consisting of a capacitor, a thyristor and a resistor. The mechanical switch is opened in a zero-current state, and the overvoltage caused by the counter electromotive force of the inductor does not exist. Meanwhile, the capacitor has a buffering effect on the voltage. The rising of the voltage of the mechanical switch is slower than the rising of the insulating strength of a contact gap of the mechanical switch, resulting in the contact gap not able to be broken down. Thus, the arc cannot be generated. The simulation results show that the proposed DCCB does not generate the arc in the interruption process, the rise rate of the short circuit current can be effectively limited, and the short circuit fault point can be rapidly isolated from the dc power supply.

  13. Influencia de la generación distribuida en los niveles de cortocircuito y en las protecciones eléctricas en subestaciones de 110 / 34,5 kV; The effects caused due to the introduction of Distribution Generation in the short-circuit levels and the protecti

    Directory of Open Access Journals (Sweden)

    Marta Bravo de las Casas

    2011-02-01

    Full Text Available En este trabajo se muestran algunos resultados de los efectos provocados por la introducción de la GD enlas redes cubanas en lo que respecta a los niveles de cortocircuito y los ajustes de las protecciones en cincosubestaciones de 110 / 34,5 kV ubicadas en las provincias de Villa Clara, Cienfuegos y Sancti Spíritus. Seobtuvieron conclusiones importantes con respecto a las necesidades de funciones de protección y criteriosde ajuste de las protecciones. Además, con respecto a la necesidad de tener en las subestaciones relésdigitales modernos con el fin de que puedan responder correctamente y en el menor tiempo posible a losdiferentes escenarios de operación que tendrá el sistema en las nuevas condiciones y así corresponder a lasexigencias que impone la GD a los esquemas de protección. In this article, results are shown of the effects caused due to the introduction of Distribution Generation(DG in the Cuban Networks with respect to short-circuit levels and the protection settings of five 110/34.5kV substations located in the provinces of Villa Clara, Cienfuegos y Sancti Spíritus. Important conclusionshave been obtained with respect to the necessities of the protection functions and their settings criteria.Besides, with respect to the necessity of having modern digital relays in order to respond correctly and inthe least possible time to the different stages of operation that the system may have in the new conditionsof operation and in this manner corresponds to the demands that the DG imply in protection systems. 

  14. Resveratrol Inhibits Porcine Intestinal Glucose and Alanine Transport: Potential Roles of Na+/K+-ATPase Activity, Protein Kinase A, AMP-Activated Protein Kinase and the Association of Selected Nutrient Transport Proteins with Detergent Resistant Membranes

    Directory of Open Access Journals (Sweden)

    Stefanie Klinger

    2018-03-01

    Full Text Available Background: Beneficial effects of Resveratrol (RSV have been demonstrated, including effects on transporters and channels. However, little is known about how RSV influences intestinal transport. The aim of this study was to further characterize the effects of RSV on intestinal transport and the respective mechanisms. Methods: Porcine jejunum and ileum were incubated with RSV (300 µM, 30 min in Ussing chambers (functional studies and tissue bathes (detection of protein expression, phosphorylation, association with detergent resistant membranes (DRMs. Results: RSV reduced alanine and glucose-induced short circuit currents (ΔIsc and influenced forskolin-induced ΔIsc. The phosphorylation of sodium–glucose-linked transporter 1 (SGLT1, AMP-activated protein kinase (AMPK, protein kinase A substrates (PKA-S and liver kinase B1 (LKB1 increased but a causative relation to the inhibitory effects could not directly be established. The DRM association of SGLT1, peptide transporter 1 (PEPT1 and (phosphorylated Na+/H+-exchanger 3 (NHE3 did not change. Conclusion: RSV influences the intestinal transport of glucose, alanine and chloride and is likely to affect other transport processes. As the effects of protein kinase activation vary between the intestinal localizations, it would appear that increasing cyclic adenosine monophosphate (cAMP levels are part of the mechanism. Nonetheless, the physiological responses depend on cell type-specific structures.

  15. Design and implementation of a bidirectional current-controlled voltage-regulated DC-DC switched-mode converter

    CSIR Research Space (South Africa)

    Coetzer, A

    2016-01-01

    Full Text Available . That is to say, 2 A. 2.1 Soft Start Circuit The two-stage soft-start circuit comprises pre- and post-charge mechanisms [1]. The pre-charge circuit limits the peak battery in-rush current to 5 A by means of four parallel connected 100 Ω resistors. At such time... as the bus capacitor C is charged to the battery potential (through the anti-parallel diode of switch Q1) the resistors are short-circuited by a relay (effectively removing the resistors from circuit). A resistor divider (connected across the DC bus), a...

  16. Study of current instabilities in high resistivity gallium arsenide; Etude des instabilites de courant dans l'arseniure de gallium de haute resistivite

    Energy Technology Data Exchange (ETDEWEB)

    Barraud, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1968-07-01

    We have shown the existence and made a study of the current oscillations produced in high-resistivity gallium arsenide by a strong electric field. The oscillations are associated with the slow travelling of a region of high electrical field across the whole sample. An experimental study of the properties of these instabilities has made it possible for us to distinguish this phenomenon from the Gunn effect, from acoustic-electric effects and from contact effects. In order to account for this type of instability, a differential trapping mechanism involving repulsive impurities is proposed; this mechanism can reduce the concentration of charge carriers in the conduction band at strong electrical fields and can lead to the production of a high-field domain. By developing this model qualitatively we have been able to account for all the properties of high-resistance gallium arsenide crystals subjected to a strong electrical field: increase of the Hall constant, existence of a voltage threshold for these oscillations, production of domains of high field, low rate of propagation of these domains, and finally the possibility of inverting the direction of the propagation of the domain without destroying the latter. A quantitative development of the model makes it possible to calculate the various characteristic parameters of these instabilities. Comparison with experiment shows that there is a good agreement, the small deviations coming especially from the lack of knowledge concerning transport properties in gallium arsenide subjected to high fields. From a study of this model, it appears that the instability phenomenon can occur over a wide range of repulsive centre concentrations, and also for a large range of resistivities. This is the reason why it appears systematically in gallium arsenide of medium and high resistivity. (authors) [French] Nous avons mis en evidence et etudie des oscillations de courant qui se produisent a champ electrique eleve dans l

  17. Method and device for current driven electric energy conversion

    DEFF Research Database (Denmark)

    2012-01-01

    Device comprising an electric power converter circuit for converting electric energy. The converter circuit comprises a switch arrangement with two or more controllable electric switches connected in a switching configuration and controlled so as to provide a current drive of electric energy from...... an associated electric source connected to a set of input terminals. This is obtained by the two or more electric swiches being connected and controlled to short-circuit the input terminals during a part of a switching period. Further, a low pass filter with a capacitor and an inductor are provided to low pass...... distance transmission of electric energy. In many applications the total size of filter components (capacitors and inductors) can be reduced compared to voltage driven topologies. One application is an audio amplifier arranged to drive a loudspeaker....

  18. Lowering resistance of the Hoyle Pond Mine

    Energy Technology Data Exchange (ETDEWEB)

    Desjardins, M. [Goldcorp Canada Ltd., Porcupine Gold Mines, Hoyle Pond Mine, Timmins, ON (Canada)

    2010-07-01

    The Hoyle Pond underground mine is located in the Porcupine Gold Camp, east of Timmins, Ontario. Various mining methods are used to excavate the gold, each with different ventilation requirements in terms of layout and volume. The mine was originally designed as a shallow mine but is planning to reach a depth of 2500 m. This paper described the events that lead to the high system pressures encountered at the mine, and the measures taken to reduce them. New surface fans and a new fresh air raise (FAR) were commissioned in 2005. The old FAR had to be sealed as soon as the new fans were in place in order to prevent short-circuiting. As a result, the mine resistance curve steepened considerably. The total pressure at the fan increased from 1500 Pa to 3000 Pa. As such, only 1 surface fan could operate at any give time, providing only half the possible volume of air. The challenge was to reduce the mine's resistance while getting the desired volume of air down to to the mining faces at depth. The solutions were to install booster fans and initiate a raise-bore program that would link the 450 m level to 900 m level. These measures twinned the existing fresh air circuit and resulted in a lowering of the overall mine resistance curve. 1 ref., 9 figs.

  19. Influence of stabilizer thickness on over-current test of YBCO-coated conductors

    Science.gov (United States)

    Kwon, N. Y.; Kim, H. S.; Kim, K. L.; Yim, S. W.; Kim, H.-R.; Hyun, O.-B.; Kim, H. M.; Lee, H. G.

    2009-04-01

    The increased use of distributed power generation has led to increasingly high fault current levels. A superconducting fault current limiter (SFCL) is a potential solution to prevent the problem of short-circuit currents. YBCO-coated conductors (CCs) are one of the most promising superconducting materials for SFCLs. Most YBCO CCs have stabilizers, which play a significant role in limiting the fault current in the SFCL. Therefore, the selection of the appropriate material and the thickness of the stabilizer of the CC used for the SFCL may affect its quench/recovery characteristics. In this paper, the quench/recovery characteristics of YBCO CC tapes having stabilizers with various thicknesses were investigated. The quench/recovery test results showed that, as the thickness of the stabilizer decreased, both the final approach temperature and the recovery time decreased.

  20. Impact of wind power plant reactive current injection during asymmetrical grid faults

    DEFF Research Database (Denmark)

    Göksu, Ömer; Teodorescu, Remus; Bak, Claus Leth

    2013-01-01

    ) are requested to stay connected and inject positive-sequence reactive current in order to boost positive-sequence grid voltage during short-circuit grid faults, irrespective of the fault type; symmetrical or asymmetrical. However, as shown in this study, when WPPs inject pure positive-sequence reactive current...... in case of asymmetrical faults, as a conventional method (CM) in accordance with the grid code requirement, positive-sequence grid voltage is boosted, but also higher negative sequence voltage in the grid and higher overvoltages at the non-faulty phases occur. In this study, an alternative injection...... method, where WTs are injecting both positive and negative sequence currents during asymmetrical faults, providing improved grid support, is given and compared with the CM. In addition, effect of coupling between positive, negative and zero sequences when WPPs are injecting currents during asymmetrical...

  1. A high current pulsed power generator CQ-3-MMAF with co-axial cable transmitting energy for material dynamics experiments

    Science.gov (United States)

    Wang, Guiji; Chen, Xuemiao; Cai, Jintao; Zhang, Xuping; Chong, Tao; Luo, Binqiang; Zhao, Jianheng; Sun, Chengwei; Tan, Fuli; Liu, Cangli; Wu, Gang

    2016-06-01

    A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mΩ and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 μF, an inductance of 11.7 nH, a resistance of 4.3 mΩ, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10-2 Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physics® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak

  2. A high current pulsed power generator CQ-3-MMAF with co-axial cable transmitting energy for material dynamics experiments.

    Science.gov (United States)

    Wang, Guiji; Chen, Xuemiao; Cai, Jintao; Zhang, Xuping; Chong, Tao; Luo, Binqiang; Zhao, Jianheng; Sun, Chengwei; Tan, Fuli; Liu, Cangli; Wu, Gang

    2016-06-01

    A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mΩ and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 μF, an inductance of 11.7 nH, a resistance of 4.3 mΩ, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10(-2) Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physics® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak

  3. Electron transfer at the contact between Al electrode and gold nanoparticles of polymer: Nanoparticle resistive switching devices studied by alternating current impedance spectroscopy

    International Nuclear Information System (INIS)

    Ouyang, Jianyong

    2013-01-01

    Electron transfer at the contact between an Al electrode and Au nanoparticles of polymer:nanoparticle devices is studied by ac impedance spectroscopy. The devices have a polystyrene layer embedded with Au nanoparticles capped with conjugated 2-naphthalenethiol sandwiched between Al and MoO 3 /Al electrodes, and they exhibit electrode-sensitive resistive switches. The devices in the pristine or high resistance state have high capacitance. The capacitance decreases after the devices switch to a low resistance state by a voltage scan. The change in the capacitance is attributed to the voltage-induced change on the electronic structure of the contact between the Al electrode and Au nanoparticles

  4. Research of grounding capacitive current of neutral non-grounding auxiliary system in nuclear power plants

    International Nuclear Information System (INIS)

    Yang Shan; Liu Li; Huang Xiaojing

    2014-01-01

    In the domestic and abroad standards, the grounding capacitive current limitation in the non-grounding electric auxiliary system is less than 10 A. Limiting capacitive current in the standard aims to speed up the arc extinguishing to reduce the duration of arc over-voltage, but not to prevent the arc producing, The arc over-voltage harm is related to the multiple, frequency and duration of the over-voltage. When the insulation vulnerabilities appear in the equipment, the arc over-voltage may result in insulation vulnerabilities of the electrical equipment breakdown, which leads to multiple, short-circuit accidents. The cable connector, accessory and electromotor winding are all insulation vulnerabilities. Setting the arc suppression coil which can counteract the grounding capacitive current makes the arc vanish quickly. Using the casting bus which remarkably reduces the ground capacitance of the electric transmission line makes the equipment safer. (authors)

  5. Flux-lock type of superconducting fault current limiters: A comprehensive review

    Science.gov (United States)

    Badakhshan, M.; Mousavi G., S. M.

    2018-04-01

    Power systems must be developed and extended to supply the continuous enhancement of demands for electrical energy. This development of systems in addition to the integration of distributed generation (DG) units to the power systems results higher capacity of system. Hence, short circuit current of network is confronted with persistent increasing. Since exploration of high temperature superconducting (HTS) materials, superconducting fault current limiters (SFCLs) have attracted a lot of attention all over the world. There are different types of SFCLs. Flux-lock type of SFCL because of its characteristics in fault current limitation is an important category of SFCLs. This paper aims to present a comprehensive review of research activities and applications of Flux-lock type of SFCLs in power systems.

  6. Improving the efficiency of copper indium gallium (Di-selenide (CIGS solar cells through integration of a moth-eye textured resist with a refractive index similar to aluminum doped zinc oxide

    Directory of Open Access Journals (Sweden)

    M. Burghoorn

    2014-12-01

    Full Text Available Textured transparent conductors are widely used in thin-film silicon solar cells. They lower the reflectivity at interfaces between different layers in the cell and/or cause an increase in the path length of photons in the Si absorber layer, which both result in an increase in the number of absorbed photons and, consequently, an increase in short-circuit current density (Jsc and cell efficiency. Through optical simulations, we recently obtained strong indications that texturing of the transparent conductor in copper indium gallium (di-selenide (CIGS solar cells is also optically advantageous. Here, we experimentally demonstrate that the Jsc and efficiency of CIGS solar cells with an absorber layer thickness (dCIGS of 0.85 μm, 1.00 μm and 2.00 μm increase through application of a moth-eye textured resist with a refractive index that is sufficiently similar to AZO (nresist = 1.792 vs. nAZO = 1.913 at 633 nm to avoid large optical losses at the resist-AZO interface. On average, Jsc increases by 7.2%, which matches the average reduction in reflection of 7.0%. The average relative increase in efficiency is slightly lower (6.0%. No trend towards a larger relative increase in Jsc with decreasing dCIGS was observed. Ergo, the increase in Jsc can be fully explained by the reduction in reflection, and we did not observe any increase in Jsc based on an increased photon path length.

  7. Designing CO2-resistant oxygen-selective mixed ionic-electronic conducting membranes: guidelines, recent advances, and forward directions.

    Science.gov (United States)

    Zhang, Chi; Sunarso, Jaka; Liu, Shaomin

    2017-05-22

    CO 2 resistance is an enabling property for the wide-scale implementation of oxygen-selective mixed ionic-electronic conducting (MIEC) membranes in clean energy technologies, i.e., oxyfuel combustion, clean coal energy delivery, and catalytic membrane reactors for greener chemical synthesis. The significant rise in the number of studies over the past decade and the major progress in CO 2 -resistant MIEC materials warrant systematic guidelines on this topic. To this end, this review features the pertaining aspects in addition to the recent status and advances of the two most promising membrane materials, perovskite and fluorite-based dual-phase materials. We explain how to quantify and design CO 2 resistant membranes using the Lewis acid-base reaction concept and thermodynamics perspective and highlight the relevant characterization techniques. For perovskite materials, a trade-off generally exists between CO 2 resistance and O 2 permeability. Fluorite materials, despite their inherent CO 2 resistance, typically have low O 2 permeability but this can be improved via different approaches including thin film technology and the recently developed minimum internal electronic short-circuit second phase and external electronic short-circuit decoration. We then elaborate the two main future directions that are centralized around the development of new oxide compositions capable of featuring simultaneously high CO 2 resistance and O 2 permeability and the exploitation of phase reactions to create a new conductive phase along the grain boundaries of dual-phase materials. The final part of the review discusses various complimentary characterization techniques and the relevant studies that can provide insights into the degradation mechanism of oxide-based materials upon exposure to CO 2 .

  8. A SIMPLIFIED MODEL OF THREE-PHASE BANK OF CURRENT TRANSFORMERS IN THE DYNAMIC SIMULATION SYSTEM

    Directory of Open Access Journals (Sweden)

    I. V. Novash

    2015-01-01

    Full Text Available  The article presents and substantiates a simplified mathematical simulation model realization technique for a three-phase bank of current transformers (CT based on their nameplate data. The secondary windings and load of the current transformers form a Y-connected circuit with neutral conductor. Consistent with the presented technique the simplified mathematical simulation realizes in the dynamic-modeling environment of MatLab–Simulink–SimPowerSystems. This simulation allows obtaining the secondary current curve shape entering only the nameplate data of the CT being simulated. Thus, the simulation under consideration enables the assessment of technical feasibility of the CT from viewpoint of correct functioning of the relay protective devices during transient processes in the electric energy systems.Employing the model, the authors conduct computational experiments simulating the CT typical operating modes: short-circuit current passage with presence/absence of the direct component and short-circuit current passage with presence of the direct component and residual magnetic induction of the CT. The paper examines the modes of automatic re-closing failure at different stages of the breaker closure with oscillograms drawn illustrating each characteristic case.The authors compare two methods for the CT iron magnetization-curve assigning: manual approximation and the Ollendorf-formula approximation. Relying on this comparison they conclude on feasability of application of the magnetization-curve approximating function for the CT operating analysis during transient processes in the electric energy systems. An elaborated user-friendly graphic interface provides a means of visual assigning the CT nominal parameters, the residual magnetic induction, and the method of the transformer iron magnetization curve approximation. The results of conducted computational experiments prove feasibility of the CT-bank simulation model.

  9. Rapid thermal annealing effect on the spatial resistivity distribution of AZO thin films deposited by pulsed-direct-current sputtering for solar cells applications

    Energy Technology Data Exchange (ETDEWEB)

    Ayachi, Boubakeur, E-mail: boubakeur.ayachi@ed.univ-lille1.fr [Institute of Electronics, Microelectronics and Nanotechnology, Lille 1 University, Avenue Poincaré, UMR 8520, CS 60069, Villeneuve d’Ascq 59652 (France); Aviles, Thomas [CROSSLUX, Avenue Georges Vacher, ZI Rousset Peynier, Immeuble CCE, Rousset 13106 (France); Vilcot, Jean-Pierre [Institute of Electronics, Microelectronics and Nanotechnology, Lille 1 University, Avenue Poincaré, UMR 8520, CS 60069, Villeneuve d’Ascq 59652 (France); Sion, Cathy [Institute of Electronics, Microelectronics and Nanotechnology, Lille 1 University, Avenue Poincaré, UMR 8520, CS 60069, Villeneuve d’Ascq 59652 (France); Ecole Centrale Lille, Cité Scientifique – CS20048, Villeneuve d’Ascq 59651 (France)

    2016-03-15

    Graphical abstract: - Highlights: • High quality pulsed-DC sputtered AZO thin films were obtained after RTA treatment. • RTA for 30 s was sufficient to achieve uniform spatial resistivity distribution. • RTA for longer than 1 min showed a small increase in resistivity value. • Such improvement was attributed to grain boundaries passivation and doping activation. • In the framework of low cost solar cells development, RTA process would be helpful. - Abstract: Room temperature deposited aluminium-doped zinc oxide thin films on glass substrate, using pulsed-DC magnetron sputtering, have shown high optical transmittance and low electrical resistivity with high uniformity of its spatial distribution after they were exposed to a rapid thermal annealing process at 400 °C under N{sub 2}H{sub 2} atmosphere. It is particularly interesting to note that such an annealing process of AZO thin films for only 30 s was sufficient, on one hand to improve their optical transmittance from 73% to 86%, on the other hand to both decrease their resistivity from 1.7 × 10{sup −3} Ω cm to 5.1 × 10{sup −4} Ω cm and achieve the highest uniformity spatial distribution. To understand the mechanisms behind such improvements of the optoelectronic properties, electrical, optical, structural and morphological changes as a function of annealing time have been investigated by using hall measurement, UV–visible spectrometry, X-ray diffraction and scanning electron microscope imaging, respectively.

  10. The effect of roughness, floor polish, water, oil and ice on underfoot friction: current safety footwear solings are less slip resistant than microcellular polyurethane.

    Science.gov (United States)

    Manning, D P; Jones, C

    2001-04-01

    Research over a period of about 18 years has shown that a microcellular polyurethane known as AP66033 is the most slip-resistant safety footwear soling material on oily and wet surfaces. In recent years it has been replaced in commercially available footwear by a dual density polyurethane (DDP) which has a dense outer layer and a soft microcellular backing. This research programme has compared the slip resistance of AP66033 with DDP and some rubber solings. In addition, data were obtained on the effects of soling and floor roughness, and floor polish on slip resistance. Some data were also obtained for walking on ice. The coefficient of friction (CoF) of the solings was measured on 19 water wet surfaces in three conditions: (I) when the solings were new, (II) following abrasion to create maximum roughness and (III) after polishing. The CoF was measured on four oily surfaces after each of 11 abrasion or polishing treatments. The profound effects of the roughening of all soles and of floor roughness on the CoF were demonstrated for both wet and oily surfaces. The superior slip resistance of AP66033 was confirmed for oily and wet conditions; however, some rubbers not suitable for safety footwear achieved higher CoF values on wet floors. All of the floor polishes reduced the CoF of all floors when contaminated with water. The mean CoF of DDP solings was lower than the mean for AP66033 on wet and oily surfaces. No safety footwear soling provided adequate grip on dry ice and the CoF was reduced by water on the ice. A rubber used for rock climbing footwear was one of the most slip-resistant solings on wet surfaces in the laboratory but recorded the lowest CoF on ice. It is concluded that the incidence of occupational injuries caused by slipping could be reduced by the following: (A) returning to safety footwear soled with the microcellular polyurethane AP66033; (B) abrading all new and smooth footwear solings with a belt sanding machine coated with P100 grit; (C) avoiding

  11. Online Fault Location on AC Cables in Underground Transmission Systems using Sheath Currents

    DEFF Research Database (Denmark)

    Jensen, Christian Flytkjær; Nanayakkarab, Kasun; Rajapakse, Athula

    2014-01-01

    This paper studies online travelling wave methods for fault location on a crossbonded cable system using sheath currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system....... At 31.4 km, all cables were accessible which made it possible to apply a fault using an arc free breaker and measure the travelling waves at each end of the cable. On a crossbonded cable system, the sheaths are short circuited and grounded at both ends. This makes possible the use of low voltage...... Rogowski coils if the sheath currents contain the necessary information for accurate fault location. In this paper, this is examined by analysis of field measurements and through a study of simulations. The wavelet transform and a visual inspection method are used and the accuracy is compared. Field...

  12. Online fault location on AC cables in underground transmission systems using screen currents

    DEFF Research Database (Denmark)

    Jensen, Christian Flytkjær; Nanayakkara, O.M.K.K; Rajapakse, Athula

    This paper studies online travelling wave methods for fault location on a crossbonded cable system using screen currents. During the construction of the electrical connection to the 400 MW off shore wind farm Anholt, it was possible to perform measurements on a 38.4 km crossbonded cable system....... At 31.4 km, all cables were accessible which made it possible to apply a fault using an arc free breaker and measure the travelling waves at each end of the cable. On a crossbonded cable system, the sheath is short circuited and grounded at both ends. This makes possible the use of low voltage Rogowski...... coils if the screen currents contain the necessary information for accurate fault location. In this paper, this is examined by analysis of field measurements and through a study of simulations. The wavelet transform and visual inspection methods are used and the accuracy is compared. Field measurements...

  13. Research trend in thermally stimulated current method for development of materials and devices in Japan

    Science.gov (United States)

    Iwamoto, Mitsumasa; Taguchi, Dai

    2018-03-01

    Thermally stimulated current (TSC) measurement is widely used in a variety of research fields, i.e., physics, electronics, electrical engineering, chemistry, ceramics, and biology. TSC is short-circuit current that flows owing to the displacement of charges in samples during heating. TSC measurement is very simple, but TSC curves give very important information on charge behaviors. In the 1970s, TSC measurement contributed greatly to the development of electrical insulation engineering, semiconductor device technology, and so forth. Accordingly, the TSC experimental technique and its analytical method advanced. Over the past decades, many new molecules and advanced functional materials have been discovered and developed. Along with this, TSC measurement has attracted much attention in industries and academic laboratories as a way of characterizing newly discovered materials and devices. In this review, we report the latest research trend in the TSC method for the development of materials and devices in Japan.

  14. Resistive evolution of current profile in tokamaks, application to the optimization of Tore-supra plasma discharges; Evolution resistive du profil de courant dans les Tokamaks, application a l'optimisation des decharges de Tore Supra

    Energy Technology Data Exchange (ETDEWEB)

    Bregeon, R

    1999-03-01

    In Tokamak plasma physics, current profile shaping has now become a key issue to improve the confinement properties of the plasma discharge. The objective of this work is to study the processes governing the current diffusion when non-inductive current are playing a major role in the discharge. Ultimately, this study aims to identify the key parameters to control the plasma current density profile with external current drive heating systems such as Lower Hybrid Current drive (LHCD) or self generated current drive such as the bootstrap current. Principles of non inductive current drive and heating systems are introduced as well as bootstrap current mechanisms. Then we present the experimental study of plasma parallel electric conductivity to validate existing models. Using these results, the poloidal magnetic field flux diffusion is modelled, using toroidal co-ordinates in order to give an accurate description of the current density profiles evolution. The initial and boundary conditions required for numerical resolution of the diffusion equation are also presented. Finally, we conclude this work with the simulations of two discharges: one with Fast Wave Electron Heating and the second using Lower Hybrid Current Drive. These simulations have multiples aims: validity test of our numerical tool and to show some limits of cylindrical models. Test of electric conductivity and bootstrap current models. To identify the key parameters involved in the current diffusion processes of a high performance plasma discharge on Tore Supra. Such simulations are crucial to determine the amount of non-inductive current required to control and sustain long plasma discharges in steady state. (author)

  15. Electrical Methods: Resistivity Methods

    Science.gov (United States)

    Surface electrical resistivity surveying is based on the principle that the distribution of electrical potential in the ground around a current-carrying electrode depends on the electrical resistivities and distribution of the surrounding soils and rocks.

  16. Optimal Placement and Sizing of Fault Current Limiters in Distributed Generation Systems Using a Hybrid Genetic Algorithm

    Directory of Open Access Journals (Sweden)

    N. Bayati

    2017-02-01

    Full Text Available Distributed Generation (DG connection in a power system tends to increase the short circuit level in the entire system which, in turn, could eliminate the protection coordination between the existing relays. Fault Current Limiters (FCLs are often used to reduce the short-circuit level of the network to a desirable level, provided that they are dully placed and appropriately sized. In this paper, a method is proposed for optimal placement of FCLs and optimal determination of their impedance values by which the relay operation time, the number and size of the FCL are minimized while maintaining the relay coordination before and after DG connection. The proposed method adopts the removal of low-impact FCLs and uses a hybrid Genetic Algorithm (GA optimization scheme to determine the optimal placement of FCLs and the values of their impedances. The suitability of the proposed method is demonstrated by examining the results of relay coordination in a typical DG network before and after DG connection.

  17. Predictive digital peak current mode controller for DC-DC converters capable of operating over the full 0-100% duty cycle range

    DEFF Research Database (Denmark)

    Andersen, Karsten Holm; Nymand, Morten

    2017-01-01

    In this paper, a high performance fully digital peak current mode controller for DC-DC converters which supports the full duty cycle range from 0-100% is presented. Support for low duty cycle is very important during short circuit or converter overload and support for high duty cycle is important...... for faster response during a transient and for providing a larger output voltage range. The digital current controller is based on a new method, which estimates the inductor current in the middle of the falling current slope. The estimated inductor current is based on sampling the inductor current in either...... duty cycle range of 0-100%. The experimental results furthermore demonstrate the achievement of a very fast digital controller with a crossover frequency about 1/10 of the switching frequency, which is comparable to that obtained by analog peak current mode control....

  18. Emerging Resistance, New Antimicrobial Agents  …  but No Tests! The Challenge of Antimicrobial Susceptibility Testing in the Current US Regulatory Landscape.

    Science.gov (United States)

    Humphries, R M; Hindler, J A

    2016-07-01

    Accurate and timely performance of antimicrobial susceptibility testing (AST) by the clinical laboratory is paramount to combating antimicrobial resistance. The ability of laboratories in the United States to effectively perform ASTs is challenged by several factors. Some, such as new resistance mechanisms and the associated evolution of testing recommendations and breakpoints, are inevitable. Others are entirely man-made. These include unnecessarily strict US Food and Drug Administration (FDA) limitations on how commercial AST systems can be used for diagnostic testing, the absence of up-to-date performance data on these systems, and the lack of commercially available FDA-cleared tests for newer antimicrobial agents or for older agents with updated breakpoints. This viewpoint will highlight contemporary AST challenges faced by the clinical laboratory, and propose some solutions. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  19. Generalized space vector control for current source inverters and rectifiers

    Directory of Open Access Journals (Sweden)

    Roseline J. Anitha

    2016-06-01

    Full Text Available Current source inverters (CSI is one of the widely used converter topology in medium voltage drive applications due to its simplicity, motor friendly waveforms and reliable short circuit protection. The current source inverters are usually fed by controlled current source rectifiers (CSR with a large inductor to provide a constant supply current. A generalized control applicable for both CSI and CSR and their extension namely current source multilevel inverters (CSMLI are dealt in this paper. As space vector pulse width modulation (SVPWM features the advantages of flexible control, faster dynamic response, better DC utilization and easy digital implementation it is considered for this work. This paper generalizes SVPWM that could be applied for CSI, CSR and CSMLI. The intense computation involved in framing a generalized space vector control are discussed in detail. The algorithm includes determination of band, region, subregions and vectors. The algorithm is validated by simulation using MATLAB /SIMULINK for CSR 5, 7, 13 level CSMLI and for CSR fed CSI.

  20. Electrical resistivity change in Al:ZnO thin films dynamically deposited by bipolar pulsed direct-current sputtering and a remote plasma source

    International Nuclear Information System (INIS)

    Yang, Wonkyun; Joo, Junghoon

    2010-01-01

    The Al-doped ZnO (AZO) thin films for a transparent conducting oxide in solar cell devices were deposited by bipolar pulsed dc magnetron sputtering. This work was performed in an in-line type system and investigated AZO films in a static deposition mode and dynamic one, which is more important in the practical fields. Because of this dynamic deposition process, the zigzagged columnar structure was observed. This resulted in the decreasing electrical property, optical properties, and surface roughness. As a deposition in the dynamic mode, the resistivity increased from 1.64x10 -3 to 2.50x10 -3 Ω cm, as compared to that in the static mode, and the transmittance also decreased from 83.9% to 78.3%. To recover the disadvantage, a remote plasma source (RPS) was supported between the substrate and target for reducing zigzagged formation during the deposition. The deposition rate decreased by using RPS, but the electrical and optical properties of films got better than only dynamic mode. The resistivity and transmittance in the dynamic mode using RPS were 2.1x10 -3 Ω cm and 85.5%, respectively. In this study, the authors found the possibility to advance the electrical and optical properties of AZO thin films in the industry mode.

  1. Fault Current Characteristics of the DFIG under Asymmetrical Fault Conditions

    Directory of Open Access Journals (Sweden)

    Fan Xiao

    2015-09-01

    Full Text Available During non-severe fault conditions, crowbar protection is not activated and the rotor windings of a doubly-fed induction generator (DFIG are excited by the AC/DC/AC converter. Meanwhile, under asymmetrical fault conditions, the electrical variables oscillate at twice the grid frequency in synchronous dq frame. In the engineering practice, notch filters are usually used to extract the positive and negative sequence components. In these cases, the dynamic response of a rotor-side converter (RSC and the notch filters have a large influence on the fault current characteristics of the DFIG. In this paper, the influence of the notch filters on the proportional integral (PI parameters is discussed and the simplified calculation models of the rotor current are established. Then, the dynamic performance of the stator flux linkage under asymmetrical fault conditions is also analyzed. Based on this, the fault characteristics of the stator current under asymmetrical fault conditions are studied and the corresponding analytical expressions of the stator fault current are obtained. Finally, digital simulation results validate the analytical results. The research results are helpful to meet the requirements of a practical short-circuit calculation and the construction of a relaying protection system for the power grid with penetration of DFIGs.

  2. Highly Conformal Ni Micromesh as a Current Collecting Front Electrode for Reduced Cost Si Solar Cell

    DEFF Research Database (Denmark)

    Gupta, Nikita; Rao, K. D. M.; Gupta, Ritu

    2017-01-01

    Despite relatively high manufacturing cost, crystalline-Si solar cell continues to hold promising future due to its high energy conversion efficiency and long life. As regards cost, one pertinent issue is the top electrode metallization of textured cell surface, which typically involves screen...... printing of silver paste. The associated disadvantages call for alternative methods that can lower the cost without compromising the solar cell efficiency. In the present work, a highly interconnected one-dimensional (1D) metal wire network has been employed as front electrode on conventional Si wafers...... deposition of Ni wire network on corrugated solar cell, a short circuit current of 33.28 mA/cm2 was obtained in comparison to 20.53 mA/cm2 without the network electrode. On comparing the efficiency with the conventional cells with screen printed electrodes, a 20% increment in efficiency has been observed...

  3. The influence of current neutralization and multiple Coulomb scattering on the spatial dynamics of resistive sausage instability of a relativistic electron beam propagating in ohmic plasma

    Science.gov (United States)

    Kolesnikov, E. K.; Manuilov, A. S.; Petrov, V. S.; Klyushnikov, G. N.; Chernov, S. V.

    2017-06-01

    The influence of the current neutralization process, the phase mixing of the trajectories of electrons and multiple Coulomb scattering of electrons beam on the atoms of the background medium on the spatial increment of the growth of sausage instability of a relativistic electron beam propagating in ohmic plasma channel has been considered. It has been shown that the amplification of the current neutralization leads to a significant increase in this instability, and phase mixing and the process of multiple scattering of electrons beam on the atoms of the background medium are the stabilizing factor.

  4. Fault ride-through enhancement of fixed speed wind turbine using bridge-type fault current limiter

    Directory of Open Access Journals (Sweden)

    Mostafa I. Marei

    2016-05-01

    Full Text Available The interaction between wind energy turbines and the grid results in two main problems, increasing the short-circuit level and reducing the Fault Ride-Through (FRT capability during faults. The objective of this paper is to solve these problems, for fixed speed Wind Energy Systems (WECS, utilizing the bridge-type Fault Current Limiter (FCL with a discharging resistor. A simple cascaded control system is proposed for the FCL to regulate the terminal voltage of the generator and limit the current. The system is simulated on PSCAD/EMTDC software to evaluate the dynamic performance of the proposed WECS compensated by FCL. The simulation results show the potentials of the FCL as a simple and effective method for solving grid interconnection problems of WECS.

  5. an investigation into the applicability of natural load variation ...

    African Journals Online (AJOL)

    Rev. Anoliefo

    Currently, photvoltaic (PV) modules are characterized based on open circuit voltage, short circuit current as well as voltage and current at ... By looping through the resistors in parallel, the firmware matches load impedance to the impedance of the ..... while series resistance tended to decrease with decrease in irradiance.

  6. Prediction of DC current flow between the Otjiwarongo and Katima Mulilo regions, using 3D DC resistivity forward modelling and magnetotelluric and audio-magnetotelluric data recorded during SAMTEX

    Science.gov (United States)

    Share, P.; Jones, A. G.; Muller, M. R.; Miensopust, M. P.; Khoza, D. T.; Fourie, S.; Webb, S. J.; Thunehed, H.

    2009-12-01

    SAMTEX (Southern African Magnetotelluric Experiment) is a multinational project initiated in 2003 to study the regional-scale electrical conductivity substructure of southern Africa and to infer from it the tectonic processes involved in the formation and deformation of the southern African subcontinental lithosphere. As an additional opportunistic component to SAMTEX, audio-magnetotelluric (AMT) data were acquired during the most recent phase of the experiment (Phase IV) to investigate the local-scale conductivity substructure in the Otjiwarongo and Katima Mulilo regions (northern and north-eastern Namibia), where in future the installation of high-voltage direct current (HVDC) earth electrodes will commence. Both of the AMT surveys are situated close to the edge of the orogenic Neo-Proterozoic Ghanzi-Chobe/Damara belts (collectively termed the Damara Mobile Belt, DMB), which represents in part the collision between the Congo and Kalahari cratons during the amalgamation of South Gondwana. Previous studies using magnetotellurics (MT), magnetometer arrays and geomagnetic observatory data all point to the existence of a highly conductive mid-crustal zone which correlates well with the spatial location of the DMB. Preliminary modelling of the Otjiwarongo AMT data confirms the existence of a high conductive zone at mid-crustal depths (10-15 km), whereas in Katima Mulilo insufficient penetration of electromagnetic energy in the AMT frequency band, due to conductive sediment cover, prevents information being obtained of the conductivity at mid-crustal depths. However, at Katima Mulilo there are sparser broadband MT (BBMT) and long period MT (LMT) measurements that can be incorporated. The high conductivity of the DMB is explained by the presence of conductive materials (graphites, sulphides). In contrast, the lithospheric structure of the neighbouring Archaean cratons, the Congo and Kalahari, are generally found to be electrically resistive and therefore it is

  7. Multiple drug resistant tuberculosis in patients addicted to alcohol – a critical issue of the current tuberculosis control

    Directory of Open Access Journals (Sweden)

    I. S. Gelbert

    2015-01-01

    Full Text Available The article presents the comparative description of multiple resistant tuberculosis patients (MDR TB abusing alcohol (group 1 – 169 people, and not abusing alcohol (group 2 – 122 persons; the frequency and specificity of adverse reaction to anti-tuberculosis drugs, immediate and postponed treatment outcomes have been studied. The negative effect of the alcohol abuse on the majority of the studied rates has been found out. Disseminated forms, fibrous cavernous tuberculosis, intoxication syndrome, chronic respiratory, intestinal and liver diseases, as well as incarceration experience are observed more often among alcohol dependent MDR TB patients. It is confidently true that adverse reactions occur more often (84.6% versus 57.6%, including toxic reactions, they are more severe and intractable, especially hepato- and neuro-toxic ones.Efficiency of in-patient treatment is confidently lower in the 1st group – 61.7% versus 82.8%. The cessation of bacillary excretion was lower (69.7% versus 85.6%. The hospital mortality was also higher in the 1st group (8.6% versus 0.9%.The postponed results of 2 – 6 year follow up are worse in the patients abusing alcohol. The successful treatment outcomes with criteria of cured, treatment completed were observed in the 60.4% in the 1st group of patient, while in the 2nd group this rate made 80.8% (p < 0.05, the mortality and disability rates were also higher as well as the number of patients in whom bacillary excretion persisted (38.3% versus 19.2%, p < 0.05.70% of patients demonstrated favorable treatment outcomes. 

  8. Estimated Historical and Current Nitrogen Balances for Illinois

    Directory of Open Access Journals (Sweden)

    Mark B. David

    2001-01-01

    Full Text Available The Midwest has large riverine exports of nitrogen (N, with the largest flux per unit area to the Mississippi River system coming from Iowa and Illinois. We used historic and current data to estimate N inputs, outputs, and transformations for Illinois where human activity (principally agriculture and associated landscape drainage have had a dominant impact. Presently, ~800,000 Mg of N is added each year as fertilizer and another 420,000 Mg is biologically fixed, primarily by soybean (Glycine max L. Merr.. These annual inputs are greater than exports in grain, which results in surplus N throughout the landscape. Rivers within the state export approximately 50% of this surplus N, mostly as nitrate, and the remainder appears to be denitrified or temporarily incorporated into the soil organic matter pool. The magnitude of N losses for 1880, 1910, 1950, and 1990 are compared. Initial cultivation of the prairies released large quantities of N (~500,000 Mg N year�1, and resulted in riverine N transport during the late 19th century that appears to have been on the same order of magnitude as contemporary N losses. Riverine flux was estimated to have been at a minimum in about 1950, due to diminished net mineralization and low fertilizer inputs. Residual fertilizer N from corn (Zea mays L., biological N fixed by soybean, short-circuiting of soil water through artificial drainage, and decreased cropping-system diversity appear to be the primary sources for current N export.

  9. APPROXIMATE CALCULATION OF ACTIVE RESISTANCE AND TEMPERATURE OF THE PULSE ELECTRIC ARC CHANNEL IN A HIGH-CURRENT DISCHARGE CIRCUIT OF A POWERFUL HIGH-VOLTAGE CAPACITOR ENERGY STORAGE

    Directory of Open Access Journals (Sweden)

    M.I. Baranov

    2017-08-01

    Full Text Available Purpose. To obtain calculation correlations for active resistance Rce and maximal temperature Tme of plasma channel of pulse electric arc in the air double-electrode system (DES with metal (graphite electrodes, and also practical approbation of the obtained correlations for Rce and Tme in the conditions of high-voltage laboratory on the powerful capacity energy storage (CES of electric setting, intended for reproducing on the electric loading of protracted C- component of current of artificial lightning with the USA rationed on normative documents by amplitude-temporal parameters (ATP. Methodology. Electrophysics bases of high-voltage impulse technique, scientific and technical bases of development and creation of high-voltage high-current impulse electrical equipment, including powerful CES, and also measuring methods in discharge circuits of powerful high-voltage CES of pulse currents of millisecond temporal range. Results. On the basis of engineering approach the new results of approximate calculation of values of Rce and Tme are resulted in the plasma channel of pulse electric arc discharge in air DES of atmospheric pressure with metallic (graphite electrodes. Practical approbation of results of calculation of values of Rce and Tme is executed as it applies to air DES, to connected in a discharge circuit of powerful high-voltage CES with protracted C- of component current of artificial lightning, characterized rationed ATP. It is shown that calculation of numeral value Rce approximately in 100 times exceeds the proper value of active resistance for the plasma channel of impulsive spark of electric discharge in air DES other things being equal, and a calculation of numeral value Tme well corresponds with the known thermodynamics information for classic electric arc in air DES of atmospheric pressure with graphite electrodes. Originality. New engineering approach is developed for the approximate calculation of values of Rce and Tme in electron

  10. Fault current reduction by SFCL in a distribution system with PV using fuzzy logic technique

    Science.gov (United States)

    Mounika, M.; Lingareddy, P.

    2017-07-01

    In the modern power system, as the utilization of electric power is very wide, there is a frequent occurring of any fault or disturbance in power system. It causes a high short circuit current. Due to this fault, high currents occurs results to large mechanical forces, these forces cause overheating of the equipment. If the large size equipment are used in power system then they need a large protection scheme for severe fault conditions. Generally, the maintenance of electrical power system reliability is more important. But the elimination of fault is not possible in power systems. So the only alternate solution is to minimize the fault currents. For this the Super Conducting Fault Current Limiter using fuzzy logic technique is the best electric equipment which is used for reducing the severe fault current levels. In this paper, we simulated the unsymmetrical and symmetrical faults with fuzzy based superconducting fault current limiter. In our analysis it is proved that, fuzzy logic based super conducting fault current limiter reduces fault current quickly to a lower value.

  11. Resistance to Powdery Mildews

    DEFF Research Database (Denmark)

    Siwoszek, Agnieszka Izabela

    in majority of them. Resistance to barley powdery mildew in the field is controlled by use of resistant varieties in a combination with fungicides. Early disease management is crucial for effective control. Yet, the pathogen commonly develops fungicide resistance due to simple point mutations. Several studies...... investigated reduced fitness of plants as a cost of resistance to pathogens. In case of barley powdery mildew, most common resistance (mlo) is linked to a higher susceptibility to other pathogens and spontaneous necrosis that leads to yield reduction. Thus, there is a clear need for alternative methods of crop...... protection. In the present study, I provide an overview of the current knowledge about plant pathogens and plant disease resistance. I use Arabidopsis as a model to investigate the mechanism of non-host resistance, presumed to be the most durable and broad-spectrum form of resistance. I attempt to determine...

  12. RF current sensor

    Science.gov (United States)

    Moore, James A.; Sparks, Dennis O.

    1998-11-10

    An RF sensor having a novel current sensing probe and a voltage sensing probe to measure voltage and current. The current sensor is disposed in a transmission line to link all of the flux generated by the flowing current in order to obtain an accurate measurement. The voltage sensor is a flat plate which operates as a capacitive plate to sense voltage on a center conductor of the transmission line, in which the measured voltage is obtained across a resistance leg of a R-C differentiator circuit formed by the characteristic impedance of a connecting transmission line and a capacitance of the plate, which is positioned proximal to the center conductor.

  13. High frequency study of a short niobium/lead alloy line

    International Nuclear Information System (INIS)

    Mazuer, J.; Gilchrist, J.

    1974-01-01

    The resonant Q-factors of coaxial lines 1.42 m in length, consisting of fine niobium wires in superconducting tubes, have been studied. The lines are either open-circuited at each end or else short-circuited at each end. In either case the fundamental resonance and odd harmonics up to the ninth were observed. Various surface treatments of the wire made no appreciable difference to the Q value of the open-circuited lines. The short-circuited lines had much lower Q values due to imperfect short-circuiting contacts, and were used mainly to study the effect of a superposed direct current. This was appreciable even when the current was much smaller than the current that the wire would support without resistive transition. The additional high-frequency loss caused by the current was attributed to flux penetration. (author)

  14. Genetic analysis of streptomycin-resistant (Sm(R)) strains of Erwinia amylovora suggests that dissemination of two genotypes is responsible for the current distribution of Sm(R) E. amylovora in Michigan.

    Science.gov (United States)

    McGhee, Gayle C; Guasco, Jesse; Bellomo, Lisa M; Blumer-Schuette, Sara E; Shane, William W; Irish-Brown, Amy; Sundin, George W

    2011-02-01

    Streptomycin-resistant (Sm(R)) strains of the fire blight pathogen Erwinia amylovora were first isolated in southwest Michigan in 1991. Since that time, resistant strains have progressed northward to other apple-producing regions in the state. A total of 98.7% of Sm(R) strains isolated between 2003 and 2009 in Michigan harbored the strA-strB genes on transposon Tn5393. strA and strB encode phosphotransferase enzymes that modify streptomycin to a nonbactericidal form. Mutational resistance to streptomycin, caused by a point mutation-mediated target-site alteration of the ribosomal S12 protein, occurred in 1.3% of E. amylovora strains from Michigan. Tn5393 was originally introduced to E. amylovora on the plasmid pEa34; thus, the first Sm(R) strains isolated contained both pEa34 and the ubiquitous nonconjugative plasmid pEA29. More recently, we have observed Sm(R) strains in which Tn5393 is present on pEA29, suggesting that the transposon has moved via transposition from pEa34 to pEA29. Almost all of the strains containing Tn5393 on pEA29 had lost pEa34. Of 210 pEA29::Tn5393 plasmids examined, the transposon was inserted at either nucleotide position 1,515 or 17,527. Both of these positions were in noncoding regions of pEA29. Comparative sequencing of the housekeeping genes groEL and potentially variable sequences on pEA29 was done in an attempt to genetically distinguish Sm(R) strains from streptomycin-sensitive (Sm(S)) strains isolated in Michigan. Only 1 nucleotide difference within the total 2,660 bp sequenced from each strain was observed in 2 of 29 strains; multiple sequence differences were observed between the Michigan strains and E. amylovora control strains isolated in the western United States or from Rubus spp. Alterations in virulence observable using an immature pear fruit assay were detected in three of eight Sm(R) strains examined. Our current genetic data indicate that only two Sm(R) strain genotypes (strains containing pEA29::Tn5393 with Tn5393

  15. Measurement of Dynamic Resistance in Resistance Spot Welding

    DEFF Research Database (Denmark)

    Wu, Pei; Zhang, Wenqi; Bay, Niels

    Through years, the dynamic resistance across the electrodes has been used for weld quality estimation and contact resistance measurement. However, the previous methods of determining the dynamic resistance were mostly based on measuring the voltage and current on the secondary side...... of the transformer in resistance welding machines, implying defects from induction noise and interference with the leads connected to the electrodes for measuring the voltage. In this study, the dynamic resistance is determined by measuring the voltage on the primary side and the current on the secondary side......, as another application, the proposed method is used to measure the faying surface contact resistance....

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

    Directory of Open Access Journals (Sweden)

    R. N. Bhowmik

    2015-06-01

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

  17. Treatment-Resistant Schizophrenia

    DEFF Research Database (Denmark)

    Howes, Oliver D; McCutcheon, Rob; Agid, Ofer

    2017-01-01

    OBJECTIVE: Research and clinical translation in schizophrenia is limited by inconsistent definitions of treatment resistance and response. To address this issue, the authors evaluated current approaches and then developed consensus criteria and guidelines. METHOD: A systematic review of randomized...... antipsychotic clinical trials in treatment-resistant schizophrenia was performed, and definitions of treatment resistance were extracted. Subsequently, consensus operationalized criteria were developed through 1) a multiphase, mixed methods approach, 2) identification of key criteria via an online survey, and 3...... responsive from treatment-resistant patients. CONCLUSIONS: There is considerable variation in current approaches to defining treatment resistance in schizophrenia. The authors present consensus guidelines that operationalize criteria for determining and reporting treatment resistance, adequate treatment...

  18. Current resistance issues in antimicrobial therapy | Senekal ...

    African Journals Online (AJOL)

    The human gut contains 1013 - 1014 bacteria that are exposed to selection pressure whenever antibiotics are administered.1 The same selection pressure applies to respiratory flora, which is one of the reasons why antimicrobial therapy prescribed for the treatment of respiratory tract infection should aim to eradicate ...

  19. On-orbit performance of LIPS gallium arsenide solar cell experiment

    Science.gov (United States)

    Bavaro, T.; Francis, R.; Pennell, M.

    1984-01-01

    Telemetry from the Living Plume Shield's gallium arsenide solar panel experiment was evaluated to determine degradation. The data were culled to preclude spurious results from possible shadowing or inaccurate measurements on a cold array. Two independent methods were then used to obtain the maximum power points and the various characteristics of the solar array. Fill factor, open circuit voltage, short circuit current, and series and shunt resistances were examined. The data analysis concluded that, to date, nearly all of the solar array degradation is due to the reduction in the short circuit current.

  20. Direct Analysis of JV-Curves Applied to an Outdoor-Degrading CdTe Module (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Jordan, D; Kurtz, S.; Ulbrich, C.; Gerber, A.; Rau, U.

    2014-03-01

    We present the application of a phenomenological four parameter equation to fit and analyze regularly measured current density-voltage JV curves of a CdTe module during 2.5 years of outdoor operation. The parameters are physically meaningful, i.e. the short circuit current density Jsc, open circuit voltage Voc and differential resistances Rsc, and Roc. For the chosen module, the fill factor FF degradation overweighs the degradation of Jsc and Voc. Interestingly, with outdoor exposure, not only the conductance at short circuit, Gsc, increases but also the Gsc(Jsc)-dependence. This is well explained with an increase in voltage dependent charge carrier collection in CdTe.