WorldWideScience

Sample records for high current short

  1. A high current, short pulse electron source for wakefield accelerators

    Energy Technology Data Exchange (ETDEWEB)

    Ho, Ching-Hung.

    1992-01-01

    Design studies for the generation of a high current, short pulse electron source for the Argonne Wakefield Accelerator are presented. An L-band laser photocathode rf gun cavity is designed using the computer code URMEL to maximize the electric field on the cathode surface for fixed frequency and rf input power. A new technique using a curved incoming laser wavefront to minimize the space charge effect near the photocathode is studied. A preaccelerator with large iris to minimize wakefield effects is used to boost the drive beam to a useful energy of around 20 MeV for wakefield acceleration experiments. Focusing in the photocathode gun and the preaccelerator is accomplished with solenoids. Beam dynamics simulations throughout the preaccelerator are performed using particle simulation codes TBCI-SF and PARMELA. An example providing a useful set of operation parameters for the Argonne Wakefield Accelerator is given. The effects of the sagitta of the curved beam and laser amplitude and timing jitter effects are discussed. Measurement results of low rf power level bench tests and a high power test for the gun cavity are presented and discussed.

  2. 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.

  3. 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%

  4. The Effect of Current-Limiting Reactors on the Tripping of Short Circuits in High-Voltage Electrical Equipment

    Energy Technology Data Exchange (ETDEWEB)

    Volkov, M. S.; Gusev, Yu. P., E-mail: GusevYP@mpei.ru; Monakov, Yu. V.; Cho, Gvan Chun [National Research University “Moscow Power Engineering Institute,” (Russian Federation)

    2016-01-15

    The insertion of current-limiting reactors into electrical equipment operating at a voltage of 110 and 220 kV produces a change in the parameters of the transient recovery voltages at the contacts of the circuit breakers for disconnecting short circuits, which could be the reason for the increase in the duration of the short circuit, damage to the electrical equipment and losses in the power system. The results of mathematical modeling of the transients, caused by tripping of the short circuit in a reactive electric power transmission line are presented, and data are given on the negative effect of a current-limiting resistor on the rate of increase and peak value of the transient recovery voltages. Methods of ensuring the standard requirements imposed on the parameters of the transient recovery voltages when using current-limiting reactors in the high-voltage electrical equipment of power plants and substations are proposed and analyzed.

  5. Critical current measurements of high-temperature superconducting short samples at a wide range of temperatures and magnetic fields.

    Science.gov (United States)

    Ma, Hongjun; Liu, Huajun; Liu, Fang; Zhang, Huahui; Ci, Lu; Shi, Yi; Lei, Lei

    2018-01-01

    High-Temperature Superconductors (HTS) are potential materials for high-field magnets, low-loss transmission cables, and Superconducting Magnetic Energy Storage (SMES) due to their high upper critical magnetic field (H c2 ) and critical temperature (T c ). The critical current (I c ) of HTS, which is one of the most important parameters for superconductor application, depends strongly on the magnetic fields and temperatures. A new I c measurement system that can carry out accurate I c measurement for HTS short samples with various temperatures (4.2-80 K), magnetic fields (0-14 T), and angles of the magnetic field (0°-90°) has been developed. The I c measurement system mainly consists of a measurement holder, temperature-control system, background magnet, test cryostat, data acquisition system, and DC power supply. The accuracy of temperature control is better than ±0.1 K over the 20-80 K range and ±0.05 K when measured below 20 K. The maximum current is over 1000 A with a measurement uncertainty of 1%. The system had been successfully used for YBa 2 Cu 3 O 7-x (YBCO) tapes I c determination with different temperatures and magnetic fields.

  6. High speed, high current pulsed driver circuit

    Science.gov (United States)

    Carlen, Christopher R.

    2017-03-21

    Various technologies presented herein relate to driving a LED such that the LED emits short duration pulses of light. This is accomplished by driving the LED with short duration, high amplitude current pulses. When the LED is driven by short duration, high amplitude current pulses, the LED emits light at a greater amplitude compared to when the LED is driven by continuous wave current.

  7. 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...

  8. 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

  9. Mechanism for the acceleration of particles and emission of short-wavelength electromagnetic radiation in high-current plasmadynamic discharges in a magnetoplasma compressor

    Science.gov (United States)

    Kozlov, N. P.; Protasov, Iu. S.

    1981-09-01

    Measurements are presented of the spatial and temporal distribution of fast particles, high energy photon fluxes and current fields in the accelerator channel and ejected current region of a magnetoplasma compressor. These data are used as the bases of conclusions concerning the position of the acceleration zones and the macroscopic structure of the current-plasma shell during the emission of the fast particles. Since it is a nonconservative multiparameter system, the magnetoplasma compressor allows investigation of the emission, spatial and temporal characteristics of the X-ray emission through changes in the dynamics of the current-plasma shell, or, equivalently, by changing the dynamics, geometry and spatial position of the neutral current sheets.

  10. The effectiveness of a high output/short duration radiofrequency current application technique in segmental pulmonary vein isolation for atrial fibrillation

    DEFF Research Database (Denmark)

    Nilsson, Brian; Chen, Xu; Pehrson, Steen

    2006-01-01

    AIMS: Segmental pulmonary vein (PV) isolation by radiofrequency (RF) catheter ablation has become a curative therapy for atrial fibrillation (AF). However, the long procedure time limits the wide application of this procedure. The aim of the current study was to compare a novel ablation technique...

  11. Short-term tocolytics for preterm delivery – current perspectives

    Directory of Open Access Journals (Sweden)

    Haas DM

    2014-03-01

    Full Text Available David M Haas, Tara Benjamin, Renata Sawyer, Sara K QuinneyDepartment of Obstetrics and Gynecology, Indiana University School of Medicine, Indianapolis, IN, USAAbstract: Administration of short-term tocolytic agents can prolong pregnancy for women in preterm labor. Prolonging pregnancy has many benefits because it allows for other proven interventions, such as antenatal corticosteroid administration, to be accomplished. This review provides an overview of currently utilized tocolytic agents and the evidence demonstrating their efficacy for prolonging pregnancy by at least 48 hours. General pharmacological principles for the clinician regarding drugs in pregnancy are also briefly discussed. In general, while the choice of the best first-line short-term tocolytic drug is not clear, it is evident that use of these agents has a clear place in current obstetric therapeutics.Keywords: tocolytics, short-term, preterm delivery

  12. Short-wave diathermy: current clinical and safety practices.

    Science.gov (United States)

    Shields, Nora; Gormley, John; O'Hare, Neil

    2002-01-01

    Short-wave diathermy (SWD) is widely available, yet a comprehensive examination of current clinical practice remains absent from the literature. The present paper aims to assess clinical and safety issues in continuous (CSWD) and pulsed (PSWD) short-wave diathermy application and subsequently indicate areas for future research. A postal survey was carried out among 116 senior physiotherapists in 41 Irish hospital-based physiotherapy departments. The response rate to the study was 75%. Analysis found that PSWD was the preferred mode of treatment with 27% of respondents using it more than once daily. Respondents considered both modes of treatment indicated for a variety of conditions. CSWD was rated as an effective treatment for chronic osteoarthritis, polyarthritis, non-specific arthrosis and haematomas. PSWD was reported an effective modality for acute soft tissue injury, haematomas, acute osteoarthritis, sinusitis and rheumatoid arthritis. Dose selection varied greatly but tended to be based on the type, nature and duration of the condition. Analysis of safety practices uncovered concerning findings. Although a high level of agreement was found on measures for patient safety, 30% of respondents reported that no measures for operator safety were taken and only five respondents stated they remained a specified distance from SWD equipment. Measures to ensure the safety of other personnel in the physiotherapy department were also lacking. Given the availability of SWD equipment and its apparent efficacy in certain conditions, future research should aim to establish this by means of controlled clinical trials. The findings on safety practices underline the urgent need for comprehensive guidelines to ensure the safety of operators, patients and the general public during SWD application.

  13. Short Review: Mitigation of Current Environmental Concerns from Methanol Synthesis

    Directory of Open Access Journals (Sweden)

    Andrew Young

    2013-06-01

    Full Text Available Methanol has become a widely used and globally distributed product. Methanol is very important due to the current depletion of fossil fuels. Industrially, methanol produced from the catalytic reaction of synthetic gas composed of hydrogen, carbon monoxide, and carbon dioxide. Methanol production has brought great attention due to carbon dioxide as the main source of greenhouse gas emissions. Combined of reducing CO2 emissions and supplying an alternative fuel source has created the idea of a carbon neutral cycle called “the methanol economy”. The best catalyst for the methanol economy would show a high CO2 conversion and high selectivity for methanol production. This paper investigates research focused on catalyst development for efficient methanol synthesis from hydrogenation of carbon dioxide through added various supports and additives such as silica, zirconium, and palladium. Catalysts that displayed the highest activity included a zirconia and silicon-titanium oxide promoted Cu/Zn/Al2O3 catalyst. Alternative method of catalyst preparation, include the oxalate-gel, solid-state reaction, co-precipitation and combustion method also investigated.  © 2013 BCREC UNDIP. All rights reservedReceived: 10th October 2012; Revised: 7th February 2012; Accepted: 10th February 2013[How to Cite: Young, A., Lesmana, D., Dai, D.J., Wu, H.S. (2013. Short Review: Mitigation of Current En-vironmental Concerns from Methanol Synthesis. Bulletin of Chemical Reaction Engineering & Catalysis, 8 (1: 1-13. (doi:10.9767/bcrec.8.1.4055.1-13][Permalink/DOI: http://dx.doi.org/10.9767/bcrec.8.1.4055.1-13] | View in  |

  14. Short-circuit experiments on a high Tc-superconducting cable conductor

    DEFF Research Database (Denmark)

    Tønnesen, Ole; Jensen, E.H.; Traholt, C.

    2002-01-01

    A high temperature superconductor (HTS) cable conductor (CC) with a critical current of 2.1 kA was tested over a range of short-circuit currents up to 20 kA. The duration of the short-circuit currents is 1 s. Between each short-circuit test the critical current of the HTS CC was measured in order...

  15. Short-run and Current Analysis Model in Statistics

    Directory of Open Access Journals (Sweden)

    Constantin Anghelache

    2006-01-01

    Full Text Available Using the short-run statistic indicators is a compulsory requirement implied in the current analysis. Therefore, there is a system of EUROSTAT indicators on short run which has been set up in this respect, being recommended for utilization by the member-countries. On the basis of these indicators, there are regular, usually monthly, analysis being achieved in respect of: the production dynamic determination; the evaluation of the short-run investment volume; the development of the turnover; the wage evolution: the employment; the price indexes and the consumer price index (inflation; the volume of exports and imports and the extent to which the imports are covered by the exports and the sold of trade balance. The EUROSTAT system of indicators of conjuncture is conceived as an open system, so that it can be, at any moment extended or restricted, allowing indicators to be amended or even removed, depending on the domestic users requirements as well as on the specific requirements of the harmonization and integration. For the short-run analysis, there is also the World Bank system of indicators of conjuncture, which is utilized, relying on the data sources offered by the World Bank, The World Institute for Resources or other international organizations statistics. The system comprises indicators of the social and economic development and focuses on the indicators for the following three fields: human resources, environment and economic performances. At the end of the paper, there is a case study on the situation of Romania, for which we used all these indicators.

  16. High current and high power superconducting rectifiers

    NARCIS (Netherlands)

    ten Kate, Herman H.J.; Bunk, P.B.; Britton, R.B.; van de Klundert, L.J.M.

    1981-01-01

    Results on three experimental superconducting rectifiers are reported. Two of them are 1 kA low frequency flux pumps, one thermally and magnetically switched. The third is a low-current high-frequency magnetically switched rectifier which can use the mains directly.

  17. MICROPROCESSOR-BASED PROTECTION DEVICE ELECTRIC MOTORS AGAINST SHORT CIRCUIT CURRENTS

    Directory of Open Access Journals (Sweden)

    D. V. Ustymenko

    2010-03-01

    Full Text Available The microprocessor device of protection of electric chains of electric motors from short circuit currents, in which switching-off of a short circuit current is carried out before it achieves a shock value, is presented.

  18. Research on resistance characteristics of YBCO tape under short-time DC large current impact

    Science.gov (United States)

    Zhang, Zhifeng; Yang, Jiabin; Qiu, Qingquan; Zhang, Guomin; Lin, Liangzhen

    2017-06-01

    Research of the resistance characteristics of YBCO tape under short-time DC large current impact is the foundation of the developing DC superconducting fault current limiter (SFCL) for voltage source converter-based high voltage direct current system (VSC-HVDC), which is one of the valid approaches to solve the problems of renewable energy integration. SFCL can limit DC short-circuit and enhance the interrupting capabilities of DC circuit breakers. In this paper, under short-time DC large current impacts, the resistance features of naked tape of YBCO tape are studied to find the resistance - temperature change rule and the maximum impact current. The influence of insulation for the resistance - temperature characteristics of YBCO tape is studied by comparison tests with naked tape and insulating tape in 77 K. The influence of operating temperature on the tape is also studied under subcooled liquid nitrogen condition. For the current impact security of YBCO tape, the critical current degradation and top temperature are analyzed and worked as judgment standards. The testing results is helpful for in developing SFCL in VSC-HVDC.

  19. High-current electron accelerator

    Science.gov (United States)

    Alekseyev, B. V.; Gorelikov, I. M.; Kazurov, V. I.; Mashkov, L. V.; Greshko, A. G.; Soklakov, G. I.; Fedorenko, A. I.; Yurekevich, K. B.

    1986-02-01

    A high current electron accelerator was developed and built on the basis of computer aided design calculations and electrolytic trough simulation. A 15 stage Arkadyev/Marx pulse voltage generator serves as the primary energy storing device. Each stage consists of two IK-100-0.4 capacitors connected in parallel and all immersed in transformer oil inside a metal container on electrically insulating posts. Each stage is shielded on both the positive and negative potential side. The shields, made of copper foil, not only smooth the electric field in the clearances but also constitute part of the commutating circuit and contribute to reduction of the overall generator size. The pulse voltage generator is triggered by a synchronizer through the conventional firing circuit of a TGI1-350/16 thyratron. To operate the accelerator in the nanosecond mode, the generator discharges into a diode through a twin shaping line. In this mode the accelerator can produce 0.8 MeV to 240 kA electron beams of 0.8 ns duration. To operate in the microsecond mode, the shaping line acts as storing capacitor, and the discharge gaps must be charged with polarity reversal in each stage. In this mode the accelerator can produce 0.5 MeV to 10 kA electron beams of 1 microsecond duration.

  20. Current concepts, classification, and results in short stem hip arthroplasty.

    Science.gov (United States)

    Falez, Francesco; Casella, Filippo; Papalia, Matteo

    2015-03-01

    Various short hip stems have been introduced with differing implant concepts of femoral fixation and implant length. There is a lack of proper classification for short hip stems, with a clear and accepted definition for implant length and extent of bone preservation in the metaphyseal and diaphyseal femur. This study analyzed the length of short hip stems. Stems were divided into collum, partial collum, and trochanter-sparing implants. An additional category was added, trochanter harming, which was defined as interruption of the circumferential integrity of the femoral neck. For all of the femoral components described, the designs were compared, excluding stems with insufficient clinical data. The 15 finally selected stems were classified as collum (1 stem), partial collum (7 stems), trochanter sparing (4 stems), and trochanter harming (3 stems). Mid-term results (>5 years of follow-up) were available for only 3 designs in the partial collum group. Taking into account the results of short-term studies (<5 years of follow-up), the femoral revision rate per 100 observed component years was <1 for most total hip arthroplasties. However, the studies varied greatly regarding level of significance, and short hip stems without published results are available commercially. Short hip stems cannot be circumscribed by a simple length limit. For some designs, clinical data collected from large patient cohorts showed a survivorship comparable to traditional stems. In cases that must be revised, this often can be performed with a conventional primary stem, fulfilling the promise to preserve bone for potential future revisions in younger patients. Copyright 2015, SLACK Incorporated.

  1. Short-channel drain current model for asymmetric heavily / lightly ...

    Indian Academy of Sciences (India)

    PRADIPTA DUTTA

    2017-07-29

    Jul 29, 2017 ... transistors (MOSFETs) is a good practice for semicon- ductor industry to achieve higher packing density and better circuit performance. But down-scaling has some disadvantages also. These small scaled devices suffer from various types of short channel effects like veloc- ity saturation, drain-induced ...

  2. High-Current Rotating Contactor

    Science.gov (United States)

    Hagan, David W.; Wolff, Edwin D.

    1996-01-01

    Rotating electrical contactor capable of carrying 1,000 amperes of current built for use in rotating large workpiece in electroplating bath. Electrical contact made by use of 24 automotive starter motor brushes adapted to match inside diameter of shell electrode.

  3. Short-run analysis of fiscal policy and the current account in a finite horizon model

    OpenAIRE

    Heng-fu Zou

    1995-01-01

    This paper utilizes a technique developed by Judd to quantify the short-run effects of fiscal policies and income shocks on the current account in a small open economy. It is found that: (1) a future increase in government spending improves the short-run current account; (2) a future tax increase worsens the short-run current account; (3) a present increase in the government spending worsens the short-run current account dollar by dollar, while a present increase in the income improves the cu...

  4. High temperature superconductor current leads

    Science.gov (United States)

    Hull, John R.; Poeppel, Roger B.

    1995-01-01

    An electrical lead having one end for connection to an apparatus in a cryogenic environment and the other end for connection to an apparatus outside the cryogenic environment. The electrical lead includes a high temperature superconductor wire and an electrically conductive material distributed therein, where the conductive material is present at the one end of the lead at a concentration in the range of from 0 to about 3% by volume, and at the other end of the lead at a concentration of less than about 20% by volume. Various embodiments are shown for groups of high temperature superconductor wires and sheaths.

  5. Current barriers to confine high frequency common mode currents

    NARCIS (Netherlands)

    Moonen, Dominicus Johannes Guilielmus; Buesink, Frederik Johannes Karel; Leferink, Frank Bernardus Johannes

    2016-01-01

    A commercially produced three phase power line filter is submitted to a Current Barrier (CB) Electro-Magnetic Compatibility (EMC) zoning strategy as an attempt to confine high frequency common mode currents. The intent of the paper is not to show how to build a ’perfect’ filter, since this is known.

  6. Short-Term Forecasting of Radiation Belt and Ring Current

    Science.gov (United States)

    Fok, Mei-Ching

    2007-01-01

    A computer program implements a mathematical model of the radiation-belt and ring-current plasmas resulting from interactions between the solar wind and the Earth s magnetic field, for the purpose of predicting fluxes of energetic electrons (10 keV to 5 MeV) and protons (10 keV to 1 MeV), which are hazardous to humans and spacecraft. Given solar-wind and interplanetary-magnetic-field data as inputs, the program solves the convection-diffusion equations of plasma distribution functions in the range of 2 to 10 Earth radii. Phenomena represented in the model include particle drifts resulting from the gradient and curvature of the magnetic field; electric fields associated with the rotation of the Earth, convection, and temporal variation of the magnetic field; and losses along particle-drift paths. The model can readily accommodate new magnetic- and electric-field submodels and new information regarding physical processes that drive the radiation-belt and ring-current plasmas. Despite the complexity of the model, the program can be run in real time on ordinary computers. At present, the program can calculate present electron and proton fluxes; after further development, it should be able to predict the fluxes 24 hours in advance

  7. High temperature superconducting fault current limiter

    Science.gov (United States)

    Hull, John R.

    1997-01-01

    A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

  8. INVESTIGATION OF MICROPROCESSOR TRANSFORMER CURRENT PROTECTION IN SHORT CIRCUIT FAULT MODES

    Directory of Open Access Journals (Sweden)

    M. S. Loman

    2014-01-01

    Full Text Available The paper presents an investigation on transformer current protection with blocking against magnetizing inrush current in short circuit fault modes. It has been shown that the proposed magnetizing in-rush current blocking algorithm can be implemented in microprocessor current protections of transformers.

  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. High pressure, high current, low inductance, high reliability sealed terminals

    Science.gov (United States)

    Hsu, John S [Oak Ridge, TN; McKeever, John W [Oak Ridge, TN

    2010-03-23

    The invention is a terminal assembly having a casing with at least one delivery tapered-cone conductor and at least one return tapered-cone conductor routed there-through. The delivery and return tapered-cone conductors are electrically isolated from each other and positioned in the annuluses of ordered concentric cones at an off-normal angle. The tapered cone conductor service can be AC phase conductors and DC link conductors. The center core has at least one service conduit of gate signal leads, diagnostic signal wires, and refrigerant tubing routed there-through. A seal material is in direct contact with the casing inner surface, the tapered-cone conductors, and the service conduits thereby hermetically filling the interstitial space in the casing interior core and center core. The assembly provides simultaneous high-current, high-pressure, low-inductance, and high-reliability service.

  11. 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.

  12. High Current Ion Sources and Injectors for Heavy Ion Fusion

    Energy Technology Data Exchange (ETDEWEB)

    Kwan, Joe W.

    2005-02-15

    Heavy ion beam driven inertial fusion requires short ion beam pulses with high current and high brightness. Depending on the beam current and the number of beams in the driver system, the injector can use a large diameter surface ionization source or merge an array of small beamlets from a plasma source. In this paper, we review the scaling laws that govern the injector design and the various ion source options including the contact ionizer, the aluminosilicate source, the multicusp plasma source, and the MEVVA source.

  13. Short term forecasting for HFSWR sea surface current mapping using artificial neural network

    Science.gov (United States)

    Lai, J. W.; Lu, Y. C.; Hsieh, C. M.; Liau, J. M.; Yang, W. C.

    2016-02-01

    Taiwan Ocean Research Institute (TORI) established the Taiwan Ocean Radar Observing System (TOROS) based on the CODAR high frequency surface wave radar (HFSWR). The TOROS is the first network having complete, contiguous HFSWR coverage of nation's coastline in the world. This network consisting of 17 SeaSonde radars offers coverage across approximately 190,000 square kilometers an area, over five times the size of Taiwan's entire land mass. In the southernmost and narrowest part of Taiwan, two 13 MHz and one 24 MHz radars were established along the NanWan Bay since June, 2014. NanWan Bay, the southern tip of Taiwan, is a southward semi-enclosed basin bounded by two capes and is open to the Luzon Strait. The distance between the two caps is around 12 km, and the distance from the northernmost point of the bay to the caps are 5 and 11 km, respectively. Strong tidal currents dominate the ocean circulation in the NanWan Bay and induce obvious upwelling of cold water that intrudes on to the shallow regions of NanWan Bay around spring tides. From late fall to early spring, the seaward wind dominated by the northeast monsoon often destratifies the water column and decreases the sea surface temperature inside the Bay (Lee et al, 1997). Furthermore, the Nanwan Bay is famous with well-developed fringing reefs distributed along the shoreline. In this area, 230 species of scleractinian corals, nine species of non-scleractinian reef-building corals, and 40 species of alcyonacean corals have been recorded (Dai, 1991). NanWan, in the shape of a beautiful arch, attracts large crowds of people to take all kinds of beach or water activities every summer. In order to improve the applicability of HFSWR ocean surface current data on search and rescue issue and evaluation of coral spawn dispersal, a short term forecasting model using artificial neural network (ANN) was developed in this study. That ocean surface current vectors obtained from tidal theory are added as inputs in artificial

  14. 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 Voc 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.

  15. Microbial Production of Short Chain Fatty Acids from Lignocellulosic Biomass: Current Processes and Market

    Directory of Open Access Journals (Sweden)

    Ivan Baumann

    2016-01-01

    Full Text Available Biological production of organic acids from conversion of biomass derivatives has received increased attention among scientists and engineers and in business because of the attractive properties such as renewability, sustainability, degradability, and versatility. The aim of the present review is to summarize recent research and development of short chain fatty acids production by anaerobic fermentation of nonfood biomass and to evaluate the status and outlook for a sustainable industrial production of such biochemicals. Volatile fatty acids (VFAs such as acetic acid, propionic acid, and butyric acid have many industrial applications and are currently of global economic interest. The focus is mainly on the utilization of pretreated lignocellulosic plant biomass as substrate (the carbohydrate route and development of the bacteria and processes that lead to a high and economically feasible production of VFA. The current and developing market for VFA is analyzed focusing on production, prices, and forecasts along with a presentation of the biotechnology companies operating in the market for sustainable biochemicals. Finally, perspectives on taking sustainable product of biochemicals from promise to market introduction are reviewed.

  16. Microbial Production of Short Chain Fatty Acids from Lignocellulosic Biomass: Current Processes and Market

    Science.gov (United States)

    Baumann, Ivan

    2016-01-01

    Biological production of organic acids from conversion of biomass derivatives has received increased attention among scientists and engineers and in business because of the attractive properties such as renewability, sustainability, degradability, and versatility. The aim of the present review is to summarize recent research and development of short chain fatty acids production by anaerobic fermentation of nonfood biomass and to evaluate the status and outlook for a sustainable industrial production of such biochemicals. Volatile fatty acids (VFAs) such as acetic acid, propionic acid, and butyric acid have many industrial applications and are currently of global economic interest. The focus is mainly on the utilization of pretreated lignocellulosic plant biomass as substrate (the carbohydrate route) and development of the bacteria and processes that lead to a high and economically feasible production of VFA. The current and developing market for VFA is analyzed focusing on production, prices, and forecasts along with a presentation of the biotechnology companies operating in the market for sustainable biochemicals. Finally, perspectives on taking sustainable product of biochemicals from promise to market introduction are reviewed. PMID:27556042

  17. High-Average, High-Peak Current Injector Design

    CERN Document Server

    Biedron, S G; Virgo, M

    2005-01-01

    There is increasing interest in high-average-power (>100 kW), um-range FELs. These machines require high peak current (~1 kA), modest transverse emittance, and beam energies of ~100 MeV. High average currents (~1 A) place additional constraints on the design of the injector. We present a design for an injector intended to produce the required peak currents at the injector, eliminating the need for magnetic compression within the linac. This reduces the potential for beam quality degradation due to CSR and space charge effects within magnetic chicanes.

  18. THE RATE OF CURRENT CHANGE DURING A SHORT CIRCUIT IN THE POWER CIRCUITS OF THE ELECTRIC ROLLING STOCK WITH REGARD TO EDDY CURRENTS

    Directory of Open Access Journals (Sweden)

    L. V. Dubinets

    2010-04-01

    Full Text Available In the article the issue of influence of vortical currents on rate of change of short circuit current is considered, a mathematical model for the calculation of short circuit currents in the traction mode in the power circuits of DC electric rolling stock is presented, and the research results are given.

  19. Extremely High Current, High-Brightness Energy Recovery Linac

    CERN Document Server

    Ben-Zvi, Ilan; Beavis, Dana; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Burger, Al; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Favale, Anthony; Gassner, David M; Grimes, Jacob T; Hahn, Harald; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Kneisel, Peter; Lambiase, Robert; Litvinenko, Vladimir N; McIntyre, Gary; Meng, Wuzheng; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Segalov, Zvi; Smith, Kevin T; Todd, Alan M M; Warren-Funk, L; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Yip, Kin; Zaltsman, Alex; Zhao, Yongxiang

    2005-01-01

    Next generation ERL light-sources, high-energy electron coolers, high-power Free-Electron Lasers, powerful Compton X-ray sources and many other accelerators were made possible by the emerging technology of high-power, high-brightness electron beams. In order to get the anticipated performance level of ampere-class currents, many technological barriers are yet to be broken. BNL's Collider-Accelerator Department is pursuing some of these technologies for its electron cooling of RHIC application, as well as a possible future electron-hadron collider. We will describe work on CW, high-current and high-brightness electron beams. This will include a description of a superconducting, laser-photocathode RF gun and an accelerator cavity capable of producing low emittance (about 1 micron rms normalized) one nano-Coulomb bunches at currents of the order of one ampere average.

  20. Time-resolved observation of fast domain-walls driven by vertical spin currents in short tracks

    Energy Technology Data Exchange (ETDEWEB)

    Sampaio, Joao; Lequeux, Steven; Chanthbouala, Andre; Cros, Vincent; Grollier, Julie [Unité Mixte de Physique CNRS/Thales and Université Paris-Sud 11, 1 Ave. A. Fresnel, 91767 Palaiseau (France); Metaxas, Peter J. [Unité Mixte de Physique CNRS/Thales and Université Paris-Sud 11, 1 Ave. A. Fresnel, 91767 Palaiseau (France); School of Physics, M013, University of Western Australia, 35 Stirling Highway, Crawley WA 6009 (Australia); Matsumoto, Rie; Yakushiji, Kay; Kubota, Hitoshi; Fukushima, Akio; Yuasa, Shinji [National Institute of Advanced Industrial Science and Technology (AIST) 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568 (Japan); Nishimura, Kazumasa; Nagamine, Yoshinori; Maehara, Hiroki; Tsunekawa, Koji [Process Development Center, Canon ANELVA Corporation, Kurigi 2-5-1, Asao, Kawasaki, Kanagawa 215-8550 (Japan)

    2013-12-09

    We present time-resolved measurements of the displacement of magnetic domain-walls (DWs) driven by vertical spin-polarized currents in track-shaped magnetic tunnel junctions. In these structures, we observe very high DW velocities (600 m/s) at current densities below 10{sup 7} A/cm{sup 2}. We show that the efficient spin-transfer torque combined with a short propagation distance allows avoiding the Walker breakdown process and achieving deterministic, reversible, and fast (≈1 ns) DW-mediated switching of magnetic tunnel junction elements, which is of great interest for the implementation of fast DW-based spintronic devices.

  1. Short-channel drain current model for asymmetric heavily / lightly doped DG MOSFETs

    Science.gov (United States)

    Dutta, Pradipta; Syamal, Binit; Koley, Kalyan; Dutta, Arka; Sarkar, C. K.

    2017-08-01

    The paper presents a drain current model for double gate metal oxide semiconductor field effect transistors (DG MOSFETs) based on a new velocity saturation model that accounts for short-channel velocity saturation effect independently in the front and the back gate controlled channels under asymmetric front and back gate bias and oxide thickness. To determine the front and the back-channel velocity saturation, drain-induced barrier lowering is evaluated by effective gate voltages at the front and back gates obtained from surface potential at the threshold condition after considering symmetric and asymmetric front and back oxide thickness. The model also incorporates surface roughness scattering and ionized impurity scattering to estimate drain current for heavily / lightly doped channel for short-channel asymmetric DG MOSFET and a good agreement has been achieved with TCAD simulations, with a relative error of around 3-7%.

  2. Weed management in short rotation coppice: current status and future requirements

    Energy Technology Data Exchange (ETDEWEB)

    Clay, D.V. [Avon Vegetation Research, Nailsea (United Kingdom)

    1996-11-01

    The current status of weed management in short rotation coppices (SRCs) is reviewed in this updated report from the Energy Technology Support Unit, which draws on data from recently published material and from experimental work on advisory and vegetation monitoring activities from large scale SRC plantings. The report covers the need for weed control in SRCs, current methods, the properties and costs of herbicides, problem weed control. The need for the development and operation of sustainable integrated weed management systems is also highlighted. (UK)

  3. 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.

  4. Short (

    NARCIS (Netherlands)

    Telleman, Gerdien; den Hartog, Laurens

    2013-01-01

    Aim: This systematic review assessed the implant survival rate of short (<10 mm) dental implants installed in partially edentulous patients. A case report of a short implant in the posterior region have been added. Materials and methods: A search was conducted in the electronic databases of MEDLINE

  5. Association between Early Attention-Deficit/Hyperactivity Symptoms and Current Verbal and Visuo-Spatial Short-Term Memory

    Science.gov (United States)

    Gau, Susan Shur-Fen; Chiang, Huey-Ling

    2013-01-01

    Deficits in short-term memory are common in adolescents with attention-deficit/hyperactivity disorder (ADHD), but their current ADHD symptoms cannot well predict their short-term performance. Taking a developmental perspective, we wanted to clarify the association between ADHD symptoms at early childhood and short-term memory in late childhood and…

  6. High current pelletron for ion implantation

    Science.gov (United States)

    Schroeder, James B.

    1989-04-01

    Since 1984, when the first production MeV ion implanter (an NEC model MV-T30) went on-line, interest in versatile electrostatic accelerator systems for MeV ion implantation has grown. The systems use a negative ion source to inject a tandem megavolt accelerator. In early systems the 0.4 mA of charging current from the two Pelletron charging chains in the accelerator was sufficient for the low intensity of beams from the ion source. This 2-chain system, however, is no longer adequate for the much higher beam intensities from today's improved ion sources. A 4-chain charging system, which delivers 1.3 mA to the high voltage terminal, was developed and is in operation in new models of NEC S Series Pelletron accelerators. This paper describes the latest beam performance of 1 MV and 1.7 MV Pelletron accelerators with this new 4-chain charging system.

  7. High Current Energy Recovery Linac at BNL

    CERN Document Server

    Litvinenko, Vladimir N; Ben-Zvi, Ilan; Blaskiewicz, Michael; Bluem, Hans; Brennan, Joseph M; Burger, Al; Burrill, Andrew; Calaga, Rama; Cameron, Peter; Chang, Xiangyun; Cole, Michael; Connolly, Roger; Delayen, Jean R; Favale, Anthony; Gassner, David M; Hahn, Harald; Hershcovitch, Ady; Holmes, Douglas; Hseuh Hsiao Chaun; Johnson, Peter; Kayran, Dmitry; Kewisch, Jorg; Lambiase, Robert; Mahler, George; McIntyre, Gary; Meng, Wuzheng; Nehring, Thomas; Nicoletti, Tony; Oerter, Brian; Pate, David; Phillips, Larry; Preble, Joseph P; Rank, Jim; Rao, Triveni; Rathke, John; Roser, Thomas; Russo, Thomas; Scaduto, Joseph; Schultheiss, Tom; Smith, Kevin T; Todd, Alan M M; Warren Funk, L; Williams, Neville; Wu, Kuo-Chen; Yakimenko, Vitaly; Yip, Kin; Zaltsman, Alex; Zhao, Yongxiang

    2004-01-01

    We present the design and the parameters of a small Energy Recovery Linac (ERL) facility, which is under construction at BNL. This R&D facility has goals to demonstrate CW operation of ERL with average beam current in the range of 0.1 - 1 ampere, combined with very high efficiency of energy recovery. The possibility for future up-grade to a two-pass ERL is being considered. The heart of the facility is a 5-cell 703.75 MHz super-conducting RF linac with HOM damping. Flexible lattice of ERL provides a test-bed for testing issues of transverse and longitudinal instabilities and diagnostics of intense CW e-beam. We present the status and plans for this facility.

  8. High-resolution simulations of turbidity currents

    Science.gov (United States)

    Biegert, Edward; Vowinckel, Bernhard; Ouillon, Raphael; Meiburg, Eckart

    2017-12-01

    We employ direct numerical simulations of the three-dimensional Navier-Stokes equations, based on a continuum formulation for the sediment concentration, to investigate the physics of turbidity currents in complex situations, such as when they interact with seafloor topography, submarine engineering infrastructure and stratified ambients. In order to obtain a more accurate representation of the dynamics of erosion and resuspension, we have furthermore developed a grain-resolving simulation approach for representing the flow in the high-concentration region near and within the sediment bed. In these simulations, the Navier-Stokes flow around each particle and within the pore spaces of the sediment bed is resolved by means of an immersed boundary method, with the particle-particle interactions being taken into account via a detailed collision model. [Figure not available: see fulltext.

  9. High Current Energy Recovery Linac at BNL

    Energy Technology Data Exchange (ETDEWEB)

    Vladimir N. Litvinenko; Donald Barton; D. Beavis; Ilan Ben-Zvi; Michael Blaskiewicz; J.M. Brennan; A. Burrill; R. Calaga; P. Cameron; X. Chang; Roger Connolly; D. Gassner; H. Hahn; A. Hershcovitch; H.C. Hseuh; P. Johnson; D. Kayran; J. Kewisch; R. Lambiase; G. McIntyre; W. Meng; T. C. Nehring; A. Nicoletti; D. Pate; J. Rank; T. Roser; T. Russo; J. Scaduto; K. Smith; T. Srinivasan-Rao; N. Williams; K.-C. Wu; Vitaly Yakimenko; K. Yip; A. Zaltsman; Y. Zhao; H. Bluem; A. Burger; Mike Cole; A. Favale; D. Holmes; John Rathke; Tom Schultheiss; A. Todd; J. Delayen; W. Funk; L. Phillips; Joe Preble

    2004-08-01

    We present the design, the parameters of a small test Energy Recovery Linac (ERL) facility, which is under construction at Collider-Accelerator Department, BNL. This R&D facility has goals to demonstrate CW operation of ERL with average beam current in the range of 0.1 - 1 ampere, combined with very high efficiency of energy recovery. A possibility for future up-grade to a two-pass ERL is considered. The heart of the facility is a 5-cell 700 MHz super-conducting RF linac with HOM damping. Flexible lattice of ERL provides a test-bed for testing issues of transverse and longitudinal instabilities and diagnostics of intense CW e-beam. ERL is also perfectly suited for a far-IR FEL. We present the status and our plans for construction and commissioning of this facility.

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

    NARCIS (Netherlands)

    Song, X.; Polinder, H.; Liu, D.; Mijatovic, Nenad; Holbøll, Joachim; Jensen, Bogi Bech

    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

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

    NARCIS (Netherlands)

    Song, X.; Liu, D.; Polinder, H.; Mijatovic, Nenad; Holbøll, Joachim; Jensen, Bogi Bech

    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 happen at

  12. 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...

  13. High-Capacity Short-Range Optical Communication Links

    DEFF Research Database (Denmark)

    Tatarczak, Anna

    Over the last decade, we have observed a tremendous spread of end-user mobile devices. The user base of a mobile application can grow or shrink by millions per day. This situation creates a pressing need for highly scalable server infrastructure; a need nowadays satisfied through cloud computing...... offered by data centers. As the popularity of cloud computing soars, the demand for high-speed, short-range data center links grows. Vertical cavity surface emitting lasers (VCSEL) and multimode fibers (MMF) prove especially well-suited for such scenarios. VCSELs have high modulation bandwidths......, we achieve 10 Gbps over 400 m and then conrm the approach in an optimized system at 25 Gbps over 300 m. The techniques described in this thesis leverage additional degrees of freedom to better utilize the available resources of short-range links. The proposed schemes enable higher speeds and longer...

  14. Three-Dimensional Finite-Element Analysis of the Short-Time and Peak Withstand Current Tests in Substation Connectors

    Directory of Open Access Journals (Sweden)

    Francesca Capelli

    2016-05-01

    Full Text Available Power devices intended for high-voltage systems must be tested according to international standards, which includes the short-time withstand current test and peak withstand current test. However, these tests require very special facilities which consume huge amounts of electrical power. Therefore, mathematical tools to simulate such tests are highly appealing since they allow reproducing the electromagnetic and thermal behavior of the test object in a fast and economical manner. In this paper, a three-dimensional finite element method (3D-FEM approach to simulate the transient thermal behavior of substation connectors is presented and validated against experimental data. To this end, a multiphysics 3D-FEM method is proposed, which considers both the connector and the reference power conductors. The transient and steady-state temperature profiles of both the conductors and connector provided by the 3D-FEM method prove its suitability and accuracy as compared to experimental data provided by short-circuit tests conducted in two high-current laboratories. The proposed simulation tool, which was proven to be accurate and realistic, may be particularly useful during the design and optimization phases of substation connectors since it allows anticipating the results of mandatory laboratory tests.

  15. Magnetoresistive Current Sensors for High Accuracy, High Bandwidth Current Measurement in Spacecraft Power Electronics

    Science.gov (United States)

    Slatter, Rolf; Goffin, Benoit

    2014-08-01

    The usage of magnetoresistive (MR) current sensors is increasing steadily in the field of power electronics. Current sensors must not only be accurate and dynamic, but must also be compact and robust. The MR effect is the basis for current sensors with a unique combination of precision and bandwidth in a compact package. A space-qualifiable magnetoresistive current sensor with high accuracy and high bandwidth is being jointly developed by the sensor manufacturer Sensitec and the spacecraft power electronics supplier Thales Alenia Space (T AS) Belgium. Test results for breadboards incorporating commercial-off-the-shelf (COTS) sensors are presented as well as an application example in the electronic control and power unit for the thrust vector actuators of the Ariane5-ME launcher.

  16. High Precision Current Measurement for Power Converters

    CERN Document Server

    Cerqueira Bastos, M

    2015-01-01

    The accurate measurement of power converter currents is essential to controlling and delivering stable and repeatable currents to magnets in particle accelerators. This paper reviews the most commonly used devices for the measurement of power converter currents and discusses test and calibration methods.

  17. Influence of Waveform and Current Direction on Short-Interval Intracortical Facilitation

    DEFF Research Database (Denmark)

    Delvendahl, Igor; Lindemann, Hannes; Jung, Nikolai H

    2014-01-01

    BACKGROUND: Transcranial magnetic stimulation (TMS) of the human primary motor hand area (M1-HAND) can produce multiple descending volleys in fast-conducting corticospinal neurons, especially so-called indirect waves (I-waves) resulting from trans-synaptic excitation. Facilitatory interaction...... between these I-waves can be studied non-invasively using a paired-pulse paradigm referred to as short-interval intracortical facilitation (SICF). OBJECTIVE/HYPOTHESIS: We examined whether SICF depends on waveform and current direction of the TMS pulses. METHODS: In young healthy volunteers, we applied...

  18. Compilation of current high energy physics experiments - Sept. 1978

    Energy Technology Data Exchange (ETDEWEB)

    Addis, L.; Odian, A.; Row, G. M.; Ward, C. E. W.; Wanderer, P.; Armenteros, R.; Joos, P.; Groves, T. H.; Oyanagi, Y.; Arnison, G. T. J.; Antipov, Yu; Barinov, N.

    1978-09-01

    This compilation of current high-energy physics experiments is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and the nine participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), KEK, Rutherford (RHEL), Serpukhov (SERP), and SLAC. Nominally, the compilation includes summaries of all high-energy physics experiments at the above laboratories that were approved (and not subsequently withdrawn) before about June 1978, and had not completed taking of data by 1 January 1975. The experimental summaries are supplemented with three indexes to the compilation, several vocabulary lists giving names or abbreviations used, and a short summary of the beams at each of the laboratories (except Rutherford). The summaries themselves are included on microfiche. (RWR)

  19. Current emitted by highly conducting Taylor cones

    Science.gov (United States)

    Delamora, J. Fernandez; Loscertales, I. G.

    1994-02-01

    When a liquid meniscus held at the exit of a metallic capillary tube is charged to a high voltage V, the free surface often takes the form of a cone whose apex emits a steady microjet, and thus injects a certain charge I and liquid volume Q per unit time into the surrounding gas. This work deals with liquids with relatively large conductivities K, for which the jet diameter d(j) is much smaller than the diameter d(n) of the capillary tube. In the limit d(j)/d(n) to O, the structure of the jet (d(j) and I, in particular) becomes independent of electrostatic parameters such as V or the electrode configuration, being governed mostly by the liquid properties and flow rate Q. Furthermore, the measured current is given approximately by I = f(epsilon)(gamma QK/epsilon)(exp 1/2) for a wide variety of liquids and conditions (epsilon, and gamma are, respectively, the dielectric constant of the liquid and the coefficient of interfacial tension, f(epsilon) is shown). A proposed explanation for this behavior is presented.

  20. High average current electron guns for high-power free electron lasers

    Directory of Open Access Journals (Sweden)

    Phillip Sprangle

    2011-02-01

    Full Text Available High average power free-electron lasers (FELs require high average current electron injectors capable of generating high quality, short duration electron bunches with a repetition rate equal to the frequency of the rf linac. In this paper we propose, analyze, and simulate an rf-gated, gridded thermionic electron gun for use in high average power FELs. Thermionic cathodes can provide the necessary high current, have long lifetimes, and require modest vacuums. In the proposed configuration the rf-gated grid is modulated at the fundamental and 3rd harmonic of the linac frequency. The addition of the 3rd harmonic on the grid results in shorter electron bunches. In this configuration, every rf bucket of the linac accelerating field contains an electron bunch. Particle-in-cell simulations indicate that this approach can provide the necessary charge per bunch, bunch duration, longitudinal and transverse emittance, and repetition rate for high average power FELs operating in the IR regime.

  1. 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)

  2. Short-term optical variability of high-redshift QSO's

    OpenAIRE

    Bachev, R.; Strigachev, A.; Semkov, E.

    2004-01-01

    This paper presents results of a search for short-term variability in the optical band of selected high-luminosity, high-redshift radio-quiet quasars. Each quasar has been monitored typically for 2 - 4 hours with a time resolution of 2 - 5 minutes and a photometric accuracy of about 0.01 - 0.02 mag. Due to the significant redshift (z>2), the covered wavelength range falls into the UV region (typically 1500 - 2500A). We found no statistical evidence for any continuum variations larger than 0.0...

  3. 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...... that the short circuits pose great challenges to the generator, and careful consideration should be given to protect the generator. The results presented in this paper would be beneficial to the design, operation and protection of an HTS wind turbine generator....

  4. Ultrastable low-noise current amplifier: a novel device for measuring small electric currents with high accuracy.

    Science.gov (United States)

    Drung, D; Krause, C; Becker, U; Scherer, H; Ahlers, F J

    2015-02-01

    An ultrastable low-noise current amplifier (ULCA) is presented. The ULCA is a non-cryogenic instrument based on specially designed operational amplifiers and resistor networks. It involves two stages, the first providing a 1000-fold current gain and the second performing a current-to-voltage conversion via an internal 1 MΩ reference resistor or, optionally, an external standard resistor. The ULCA's transfer coefficient is highly stable versus time, temperature, and current amplitude within the full dynamic range of ±5 nA. The low noise level of 2.4 fA/√Hz helps to keep averaging times short at small input currents. A cryogenic current comparator is used to calibrate both input current gain and output transresistance, providing traceability to the quantum Hall effect. Within one week after calibration, the uncertainty contribution from short-term fluctuations and drift of the transresistance is about 0.1 parts per million (ppm). The long-term drift is typically 5 ppm/yr. A high-accuracy variant is available that shows improved stability of the input gain at the expense of a higher noise level of 7.5 fA/√Hz. The ULCA also allows the traceable generation of small electric currents or the calibration of high-ohmic resistors.

  5. Characterization of high-current, high-temperature superconductor current lead elements

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, R.C.; Evans, D.J.; Fisher, B.L. [Argonne National Lab., IL (United States); Brockenborough, W.E.; Roberts, P.R.; Rodenbush, A.J. [American Superconductor Corp., Westborough, MA (United States)

    1996-08-01

    The refrigeration loads of current leads for superconducting magnets can be significantly reduced by using high-temperature superconductor (HTS) leads. An HTS conductor type that is well suited for this application is a laminated sintered stack of HTS powder-in-tube (PIT) tapes. The superconducting elements are normally characterized by their manufacturer by measuring critical currents at 77 K in self field. Additional characterization, which correlates electrical performance at 77 K and at lower temperatures with applied magnetic fields, provides the current lead designer and conductor element manufacturer with critical information. For HTS conductor elements comprising a laminated and sintered stack of Bi-2223 PIT tapes having an alloyed Ag sheath, this characterization uses variable applied fields and operating temperatures.

  6. Development of high temperature superconductors having high critical current density

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Gye Wong; Kim, C. J.; Lee, H.G.; Kwon, S. C.; Lee, H. J.; Kim, K. B.; Park, J. Y.; Jung, C. H

    2000-08-01

    Fabrication of high T{sub c} superconductors and its applications for electric power device were carried out for developing superconductor application technologies. High quality YBCO superconductors was fabricated by melt texture growth, top-seeded melt growth process and multi-seeded melt growth process and the properties was compared. The critical current density of the melt processed YBCO superconductors was about few 10,000 A/cm{sup 2} and the levitation force was 50 N. The processing time needed for the growth of the 123 single grain was greatly reduced by applying multi-seeding without no significant degradation of the levitation force. The multi-seeded melt growth process was confirmed as a time-saving and cost-effective method for the fabrication of bulk superconductors with controlled crystallographic orientation.

  7. Improving sensitivity of residual current transformers to high frequency earth fault currents

    Directory of Open Access Journals (Sweden)

    Czapp Stanislaw

    2017-09-01

    Full Text Available For protection against electric shock in low voltage systems residual current devices are commonly used. However, their proper operation can be interfered when high frequency earth fault current occurs. Serious hazard of electrocution exists then. In order to detect such a current, it is necessary to modify parameters of residual current devices, especially the operating point of their current transformer. The authors proposed the modification in the structure of residual current devices. This modification improves sensitivity of residual current devices when high frequency earth fault current occurs. The test of the modified residual current device proved that the authors’ proposition is appropriate.

  8. Test setups for the development of high voltage circuit breakers for high short circuit capacities

    Science.gov (United States)

    Patzelt, R.; Ruhnau, W.; Zemann, E.

    1981-10-01

    A number of test setups and procedures are described for measuring and simulating the current and voltage conditions prevailing in short circuit breakers designed to interrupt short circuit currents from 80 to 100 kA. A synthetic test circuit was successfully developed, using the principles of both voltage and current injection. A capacitance current injection procedure allows for the establishment of the influence of iron in the magnetic circuit on the prospective transient recovery voltage of the breaker. Methods for measuring the post-arc current are indicated, and developed meshed grid and tube shunts are described. Synthetic test circuits are presented which are suitable for testing the capacitive switching capabilities of breakers.

  9. Current-voltage curve of a bipolar membrane at high current density

    NARCIS (Netherlands)

    Aritomi, T.; van den Boomgaard, Anthonie; Strathmann, H.

    1996-01-01

    The potential drop across a bipolar membrane was measured as a function of the applied current density. As a result, an inflection point was observed in the obtained current-voltage curve at high current density. This inflection point indicates that at high current densities water supply from

  10. Calculation of Initial Short-Circuit Currents in Medium Voltage Networks According to the Standard PN-EN 60909

    National Research Council Canada - National Science Library

    Krzysztof Księżyk; Tomasz Zdun

    2013-01-01

    Determining the short-circuit currents is usually conducted by network analyses. An important feature of this calculation is carried out according to the recommendations of the standard PN EN 60909...

  11. Comparison of two methods for short circuit current measurement of large size solar cell

    Science.gov (United States)

    Huang, Xuebo; Quan, Chenggen; Kng, Jerald

    2015-07-01

    The differential spectral responsivity (DSR) measurement and the solar simulator based current to voltage characterisation methods are two accurate methods for measuring the short circuit current, a critical parameter, of a solar cell under standard testing conditions. For the calibration of World Photovoltaic Scale (WPVS) reference solar cell with small size (20 mm x 20 mm), the measurement results using these two methods are agreed well within 1%. But for the calibration of large size (e.g. 156 mm x 156 mm) of solar cell, the measurement results using two methods are not agreed well and their deviation could be more than 10 %. In DSR method, the short circuit current of a solar cell is determined through measuring its relative irradiance spectral responsivity in spectral range from 280 nm to 1200 nm and its absolute irradiance responsivity at wavelength of 650 nm by reference standard photodiodes. As the detective area of large size solar cell (detective area: 156 mm x 156 mm) is much bigger than that of standard photodiodes (detective area: 12.56 mm2), the spatial uniformity of irradiance of modulated monochromatic probe beam on the test solar cell and the standard photodiode is critical for calculation of absolute irradiance responsivity of the test solar cell. The correction for the calculation must be done according to the measured spatial uniformity of probe beam and the detective areas of the test solar cell and standard photodiodes. The experiment showed the correction factor and its uncertainty are smaller if the detective areas difference between the test solar cell and the standard is smaller. Based on this observation, a standard solar cell (detective area: 20 mm x 20 mm) instead of standard photodiodes was used to calibrate absolute irradiance responsivity of the test solar cell (detective area: 156 mm x 156 mm) at wavelength of 650 nm. After such improvement, measurement results using two different methods agree well about 3 % for the large size

  12. High Current Beam Transport to SIS18

    CERN Document Server

    Richter, S; Dahl, L; Glatz, J; Groening, L; Yaramishev, S

    2004-01-01

    The optimized transversal and longitudinal matching of space charged dominated ion beams to SIS18 is essential for a loss free injection. This paper focuses on the beam dynamics in the transfer line (TK) from the post-stripper accelerator to the SIS18. Transverse beam emittance measurements at different positions along the TK were done. Especially, the different foil stripping modes were investigated. A longitudinal emittance measurement set-up was commissioned at the entry to the TK. It is used extensively to tune all the rebunchers along the UNILAC. An addition, a test bench is in use for measurements of longitudinal bunch profiles, which enables to monitor for the final debunching to SIS18. Multi particle simulations by means of PARMILA allow a detailed analysis of experimental results for different ion currents.

  13. 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....

  14. Current Perspectives in High Energy Astrophysics

    Science.gov (United States)

    Ormes, Jonathan F. (Editor)

    1996-01-01

    High energy astrophysics is a space-age discipline that has taken a quantum leap forward in the 1990s. The observables are photons and particles that are unable to penetrate the atmosphere and can only be observed from space or very high altitude balloons. The lectures presented as chapters of this book are based on the results from the Compton Gamma-Ray Observatory (CGRO) and Advanced Satellite for Cosmology and Astrophysics (ASCA) missions to which the Laboratory for High Energy Astrophysics at NASA's Goddard Space Flight Center made significant hardware contributions. These missions study emissions from very hot plasmas, nuclear processes, and high energy particle interactions in space. Results to be discussed include gamma-ray beaming from active galactic nuclei (AGN), gamma-ray emission from pulsars, radioactive elements in the interstellar medium, X-ray emission from clusters of galaxies, and the progress being made to unravel the gamma-ray burst mystery. The recently launched X-ray Timing Explorer (XTE) and prospects for upcoming Astro-E and Advanced X-ray Astronomy Satellite (AXAF) missions are also discussed.

  15. The Effect of Short Duration Electric Current on the Quasi-Static Tensile Behavior of Magnesium AZ31 Alloy

    Directory of Open Access Journals (Sweden)

    Trung Thien Nguyen

    2016-01-01

    Full Text Available The effect of a single pulse of electric current with short duration on the quasi-static tensile behavior of a magnesium AZ31 alloy is experimentally investigated. A single pulse of electric current with duration less than 1 second is applied to the specimen, while the specimen is being deformed in the plastic region under quasi-static tensile loads. After a nearly instant decrease of flow stress at the pulse of electric current, the flow stress shows strain hardening until the failure of the specimen. The experimental result shows that the strain-hardening parameters (the strength coefficient and the strain-hardening exponent of the hardening curve after the electric current strongly depend on the applied electric energy density (electric energy per unit volume. Empirical expressions are suggested to describe the hardening behavior after the pulse as a function of the electric energy density and are compared with the empirical expressions suggested for advanced high-strength steels.

  16. LTS and HTS high current conductor development for DEMO

    Energy Technology Data Exchange (ETDEWEB)

    Bruzzone, Pierluigi, E-mail: pierluigi.bruzzone@psi.ch [EPFL-CRPP, Fusion Technology, CH-5232 Villigen-PSI (Switzerland); Sedlak, Kamil; Uglietti, Davide; Bykovsky, Nikolay [EPFL-CRPP, Fusion Technology, CH-5232 Villigen-PSI (Switzerland); Muzzi, Luigi; De Marzi, Gainluca; Celentano, Giuseppe; Della Corte, Antonio; Turtù, Simonetta [ENEA, Superconductivity Division, I-00044 Frascati (Italy); Seri, Massimo [TRATOS Cavi Spa, I-52036 Pieve Santo Stefano (Italy)

    2015-10-15

    Highlights: • Design and R&D for DEMO TF conductors. • Wind&react vs. react&wind options for Nb{sub 3}Sn high grade TF conductors. • Progress in the manufacture of short length Nb{sub 3}Sn proptotypes. • Design and prototype manufacture for high current HTS cabled conductors. - Abstract: The large size of the magnets for DEMO calls for very large operating current in the forced flow conductor. A plain extrapolation from the superconductors in use for ITER is not adequate to fulfill the technical and cost requirements. The proposed DEMO TF magnets is a graded winding using both Nb{sub 3}Sn and NbTi conductors, with operating current of 82 kA @ 13.6 T peak field. Two Nb{sub 3}Sn prototypes are being built in 2014 reflecting the two approaches suggested by CRPP (react&wind method) and ENEA (wind&react method). The Nb{sub 3}Sn strand (overall 200 kg) has been procured at technical specification similar to ITER. Both the Nb{sub 3}Sn strand and the high RRR, Cr plated copper wire (400 kg) have been delivered. The cabling trials are carried out at TRATOS Cavi using equipment relevant for long length production. The completion of the manufacture of the two 20 m long prototypes is expected in the end of 2014 and their test is planned in 2015 at CRPP. In the scope of a long term technology development, high current HTS conductors are built at CRPP and ENEA. A DEMO-class prototype conductor is developed and assembled at CRPP: it is a flat cable composed of 20 twisted stacks of coated conductor tape soldered into copper shells. The 10 kA conductor developed at ENEA consists of stacks of coated conductor tape inserted into a slotted and twisted Al core, with a central cooling channel. Samples have been manufactured in industrial environment and the scalability of the process to long production lengths has been proven.

  17. High current injector for heavy ion fusion

    Science.gov (United States)

    Yu, S.; Eylon, S.; Chupp, W. W.

    1993-05-01

    A 2 MV, 800 mA, K(+) injector for heavy ion fusion studies is under construction. This new injector is a one-beam version of the proposed 4-beam ILSE injector. A new 36-module MARX is being built to achieve a 5 micro-s flat top. The high voltage generator is stiff (less than 5k Omega) to minimize effects of beam-induced transients. A large (approximately 7 in. diameter) curved hot alumina-silicate source emits a 1 micro-s long beam pulse through a gridless extraction electrode, and the ions are accelerated to 1 MV in a diode configuration. Acceleration to 2 MV takes place in a set of electrostatic quadrupole (ESQ) units, arranged to simultaneously focus and accelerate the ion beam. Heavy shields and other protection devices have been built in to minimize risks of high voltage breakdown. Beam aberration effects through the ESQ have been studied extensively with theory, simulations, and scaled experiments. The design, simulations, experiments, and engineering of the ESQ injector will be presented.

  18. High-energy Emission Components in the Short GRB 090510

    Science.gov (United States)

    Corsi, Alessandra; Guetta, Dafne; Piro, Luigi

    2010-09-01

    We investigate the origin of the prompt and delayed emission observed in the short GRB 090510. We use the broadband data to test whether the most popular theoretical models for gamma-ray burst emission can accommodate the observations for this burst. We first attempt to explain the soft-to-hard spectral evolution associated with the delayed onset of a GeV tail with the hypothesis that the prompt burst and the high-energy tail both originate from a single process, namely, synchrotron emission from internal shocks (IS). Considerations on the compactness of the source imply that the high-energy tail should be produced in a late-emitted shell, characterized by a Lorentz factor greater than the one generating the prompt burst. However, in this hypothesis, the predicted evolution of the synchrotron peak frequency does not agree with the observed soft-to-hard evolution. Given the difficulties of a single-mechanism hypothesis, we test two alternative double-component scenarios. In the first, the prompt burst is explained as synchrotron radiation from IS and the high-energy emission (up to about 1 s following the trigger) as IS synchrotron-self-Compton. In the second scenario, in view of its long duration (~100 s), the high-energy tail is decoupled from the prompt burst and has an external shock origin. In this case, we show that a reasonable choice of parameters does indeed exist to accommodate the optical-to-GeV data, provided the Lorentz factor of the shocked shell is sufficiently high. Finally, we attempt to explain the chromatic break observed around ~103 s with a structured jet model. We find that this might be a viable explanation and that it lowers the high value of the burst energy derived by assuming isotropy, ~1053 erg, below ~1049 erg, which is more compatible with the energetics from a binary merger progenitor.

  19. Short-pulse high intensity laser thin foil interaction

    Science.gov (United States)

    Audebert, Patrick

    2003-10-01

    The technology of ultrashort pulse laser generation has progressed to the point that optical pulses larger than 10 J, 300 fs duration or shorter are routinely produced. Such pulses can be focused to intensities exceeding 10^18 W/cm^2. With high contrast pulses, these focused intensities can be used to heat solid matter to high temperatures with minimal hydrodynamic expansion, producing an extremely high energy-density state of matter for a short period of time. This high density, high temperature plasma can be studied by x-ray spectroscopy. We have performed experiments on thin foils of different elements under well controlled conditions at the 100 Terawatt laser at LULI to study the characteristics X-ray emission of laser heated solids. To suppress the ASE effect, the laser was frequency doubled. S-polarized light with a peak intensity of 10^19W/cm^2 was used to minimize resonance absorption. To decrease the effect of longitudinal temperature gradients very thin (800 μ) aluminum foil targets were used. We have also studied the effect of radial gradient by limiting the measured x-ray emission zone using 50μ or 100μ pinhole on target. The spectra, in the range 7-8Å, were recorded using a conical crystal spectrometer coupled to a 800 fs resolution streak camera. A Fourier Domain Interferometry (FDI) of the back of the foil was also performed providing a measurement of the hydrodynamic expansion as function of time for each shot. To simulate the experiment, we used the 1D hydrodynamic code FILM with a given set of plasma parameter (ρ, Te) as initial conditions. The X-ray emission was calculated by post processing hydrodynamic results with a collisional-radiative model which uses super-configuration average atomic data. The simulation reproduces the main features of the experimental time resolved spectrum.

  20. Control of plasma properties in a short direct-current glow discharge with active boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Adams, S. F. [Air Force Research Laboratory, WPAFB, Ohio 45433 (United States); Demidov, V. I., E-mail: vladimir.demidov@mail.wvu.edu [Air Force Research Laboratory, WPAFB, Ohio 45433 (United States); West Virginia University, Morgantown, West Virginia 26506 (United States); Bogdanov, E. A.; Kudryavtsev, A. A. [St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Koepke, M. E. [West Virginia University, Morgantown, West Virginia 26506 (United States); Kurlyandskaya, I. P. [St. Petersburg University of State Fire Service of EMERCOM RF, Murmansk Branch, Murmansk 183040 (Russian Federation)

    2016-02-15

    To demonstrate controlling electron/metastable density ratio and electron temperature by applying negative voltages to the active (conducting) discharge wall in a low-pressure plasma with nonlocal electron energy distribution function, modeling has been performed in a short (lacking the positive-column region) direct-current glow discharge with a cold cathode. The applied negative voltage can modify the trapping of the low-energy part of the energetic electrons that are emitted from the cathode sheath and that arise from the atomic and molecular processes in the plasma within the device volume. These electrons are responsible for heating the slow, thermal electrons, while production of slow electrons (ions) and metastable atoms is mostly due to the energetic electrons with higher energies. Increasing electron temperature results in increasing decay rate of slow, thermal electrons (ions), while decay rate of metastable atoms and production rates of slow electrons (ions) and metastable atoms practically are unchanged. The result is in the variation of electron/metastable density ratio and electron temperature with the variation of the wall negative voltage.

  1. Forward voltage short-pulse technique for measuring high power laser array junction temperature

    Science.gov (United States)

    Meadows, Byron L. (Inventor); Amzajerdian, Frazin (Inventor); Barnes, Bruce W. (Inventor); Baker, Nathaniel R. (Inventor)

    2012-01-01

    The present invention relates to a method of measuring the temperature of the P-N junction within the light-emitting region of a quasi-continuous-wave or pulsed semiconductor laser diode device. A series of relatively short and low current monitor pulses are applied to the laser diode in the period between the main drive current pulses necessary to cause the semiconductor to lase. At the sufficiently low current level of the monitor pulses, the laser diode device does not lase and behaves similar to an electronic diode. The voltage across the laser diode resulting from each of these low current monitor pulses is measured with a high degree of precision. The junction temperature is then determined from the measured junction voltage using their known linear relationship.

  2. Ballistic Graphene Josephson Junctions from the Short to the Long Junction Regimes: Part II- Critical current scaling of the Short and Long Junctions

    Science.gov (United States)

    Ke, Chung-Ting; Borzenets, Ivan; Amet, Francois; Draelos, Anne; Wei, Ming-Tso; Seredinski, Andrew; Watanabe, Kenji; Taniguchi, Takashi; Bomze, Yuriy; Yamamoto, Michihisa; Tarucha, Seigo; Finkelstein, Gleb

    The Josephson effect describes the phenomenon of coupling a supercurrent between superconductors through a weak link. Using graphene as this weak link has seen much interest due to its tunable density and related Dirac fermion physics. Previously we have studied the critical current scaling in diffusive graphene samples with different junction lengths. For ballistic junctions, however, knowledge about transport properties remains scarce. With clean encapsulated graphene, studying the supercurrent transport mechanism in ballistic samples has now become feasible. We present measurements of ballistic graphene Josephson junctions from short to long junction limits. From their temperature dependence, we characterize the critical current in both the short and long junction cases by using the characteristic energies Δ and δE, where Δ is the superconducting gap and δE is the level spacing in the long junction case. At low temperatures, as KBT < Δ for short junctions and KBT < δE for long ones, we show that the critical current saturates at a level determined by the product of Δ (or δE) and the number of the junction's transversal modes.

  3. Direct current induced short-term modulation of the left dorsolateral prefrontal cortex while learning auditory presented nouns

    Directory of Open Access Journals (Sweden)

    Meyer Martin

    2009-07-01

    Full Text Available Abstract Background Little is known about the contribution of transcranial direct current stimulation (tDCS to the exploration of memory functions. The aim of the present study was to examine the behavioural effects of right or left-hemisphere frontal direct current delivery while committing to memory auditory presented nouns on short-term learning and subsequent long-term retrieval. Methods Twenty subjects, divided into two groups, performed an episodic verbal memory task during anodal, cathodal and sham current application on the right or left dorsolateral prefrontal cortex (DLPFC. Results Our results imply that only cathodal tDCS elicits behavioural effects on verbal memory performance. In particular, left-sided application of cathodal tDCS impaired short-term verbal learning when compared to the baseline. We did not observe tDCS effects on long-term retrieval. Conclusion Our results imply that the left DLPFC is a crucial area involved in short-term verbal learning mechanisms. However, we found further support that direct current delivery with an intensity of 1.5 mA to the DLPFC during short-term learning does not disrupt longer lasting consolidation processes that are mainly known to be related to mesial temporal lobe areas. In the present study, we have shown that the tDCS technique has the potential to modulate short-term verbal learning mechanism.

  4. Why do short term workers have high mortality?

    DEFF Research Database (Denmark)

    Kolstad, Henrik; Olsen, Jørn

    1999-01-01

    Increased mortality is often reported among workers in short term employment. This may indicate either a health-related selection process or the presence of different lifestyle or social conditions among short term workers. The authors studied these two aspects of short term employment among 16...... to employment showed a 20% higher risk of early termination of employment than those never hospitalized (rate ratio (RR) = 1.20, 95% confidence interval (Cl) 1.16-1.29), and the risk increased with number of hospitalizations. For workers with two or more preemployment hospitalizations related to alcohol abuse...

  5. High Average Current Electron Guns for High-Power FELs

    Science.gov (United States)

    2009-12-09

    FELs 10 Appendix B: Thermionic Injectors 11 Appendix C: Grid Fields and Bunch Emittance 13 Appendix D: PARMELA Simulation of an IOT Gun 16...Inductive Output Tube ( IOT ) amplifiers [32-34] and can generate average currents of ~1 A, peak currents of ~ 5-10 A, cathode-anode voltages of ~ 35...of grid wires, centered at z = zG and x = ±a, ±3a, ±5a, ..., is given by <D(JC,Z) = - X n = ±l.±3. Fa(x,z) Gn(x,z) ( C3 ) where *0 = (1 / 2

  6. 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.

  7. Little field evidence of direct acute and short-term effects of current pesticides on the grey partridge.

    Science.gov (United States)

    Millot, Florian; Berny, Philippe; Decors, Anouk; Bro, Elisabeth

    2015-07-01

    Direct lethal and sublethal effects of pesticides on farmland birds' populations are recurring questions and largely debated. In this context, we conducted an innovative study combining radiotelemetry, farmer surveys, residue analyses on carcasses and modelling to assess the unintentional effects of pesticides on terrestrial birds. We chose the grey partridge Perdix perdix as a case study because this typical bird of European cereal ecosystems is highly exposed to pesticides. In this paper we focused on acute and short-term impacts of pesticides on adult mortality during spring and summer in a one-substance approach (multiple exposure were not studied here) but for a large variety of active substances (a.s.) actually used in cultivated farmland of Northern France. The fate and the location of 529 partridges were monitored twice a day from early March to late August 2010 and 2011 on 12 sites (14,500 ha). Their daily potential exposure to 183 a.s. was determined by overlapping birds' habitat use and daily pesticide application data. Based on this procedure, we calculated mortality rates within 10 days following a potential exposure for 157 different a.s.. 5 a.s. were associated with a "10-day mortality rate" higher than 10% but a single one (thiacloprid) is reported to be highly toxic to birds. We recorded 261 mortalities among which 94 carcasses were in suitable condition for residue analyses. We detected at least one a.s in 39.4% of carcasses. However, only 2 mortality cases were attributed to poisoning (carbofuran). Furthermore, modelling results showed that these lethal pesticide-related poisonings decreased the population growth rate by less than 1%. In conclusion, we did not point out important direct acute and short-term effects of pesticides currently used by farmers during the breeding season on the grey partridge. This is discussed with regards to the complexity of potential effects in operational conditions. Copyright © 2015 Elsevier Inc. All rights

  8. A carbon nanotube field emission cathode with high current density and long-term stability

    Energy Technology Data Exchange (ETDEWEB)

    Calderon-Colon, Xiomara; Zhou, Otto [Curriculum in Applied Science and Engineering, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States); Geng Huaizhi; Gao Bo [Xintek, Incorporated, 7020 Kit Creek Road, Research Triangle Park, NC (United States); An Lei; Cao Guohua [Department of Physics and Astronomy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599 (United States)

    2009-08-12

    Carbon nanotube (CNT) field emitters are now being evaluated for a wide range of vacuum electronic applications. However, problems including short lifetime at high current density, instability under high voltage, poor emission uniformity, and pixel-to-pixel inconsistency are still major obstacles for device applications. We developed an electrophoretic process to fabricate composite CNT films with controlled nanotube orientation and surface density, and enhanced adhesion. The cathodes have significantly enhanced macroscopic field emission current density and long-term stability under high operating voltages. The application of this CNT electron source for high-resolution x-ray imaging is demonstrated.

  9. 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.

  10. Compact submicrosecond, high current generator for wire explosion experiments

    Science.gov (United States)

    Aranchuk, L. E.; Chuvatin, A. S.; Larour, J.

    2004-01-01

    The PIAF generator was designed for low total energy and high energy density experiments with liners, X-pinch or fiber Z-pinch loads. These studies are of interest for such applications as surface and material science, microscopy of biological specimens, lithography of x-ray sensitive resists, and x-ray backlighting of pulsed-power plasmas. The generator is based on an RLC circuit that includes six NWL 180 nF-50 kV capacitors that store up to 1.3 kJ. The capacitors are connected in parallel to a single multispark switch designed to operate at atmospheric pressure. The switch allows reaching a time delay between the trigger pulse and the current pulse of less than 80 ns and has jitter of 6 ns. The total inductance without a load compartment was optimized to be as low as 16 nH, which leads to extremely low impedance of ˜0.12 Ω. A 40 kV initial voltage provides 250 kA maximum current in a 6 nH inductive load with a 180 ns current rise time. PIAF has dimensions of 660×660×490 mm and weight of less than 100 kg, thus manifesting itself as robust, simple to operate, and cost effective. A description of the PIAF generator and the initial experimental results on PIAF with an X-pinch type load are reported. The generator was demonstrated to operate successfully with an X-pinch type load. The experiments first started with investigation of the previously unexplored X-pinch conduction time range, 100 ns-1 μs. A single short radiation pulse was obtained that came from a small, point-like plasma. The following x-ray source characteristics were achieved: typical hot spot size of 50-100 μm, radiation pulse duration of 1.5-2 ns, and radiation yield of about 250-500 mJ in the softer spectral range (hν⩾700 eV) and 50-100 mJ in the harder one (hν⩾1 keV). These results provide the potential for further application of this source, such as use as a backlight diagnostic tool.

  11. Origin of the light intensity dependence of the short-circuit current of polymer/fullerene solar cells

    NARCIS (Netherlands)

    Koster, LJA; Mihailetchi, VD; Xie, H; Blom, PWM

    2005-01-01

    A typical feature of polymer/fullerene based solar cells is that the current density under short-circuit conditions (J(sc)) does not scale exactly linearly with light intensity (I). Instead, a power law relationship is found given by J(sc)proportional to I-alpha, where alpha ranges from 0.85 to 1.

  12. A superconducting transformer system for high current cable testing.

    Science.gov (United States)

    Godeke, A; Dietderich, D R; Joseph, J M; Lizarazo, J; Prestemon, S O; Miller, G; Weijers, H W

    2010-03-01

    This article describes the development of a direct-current (dc) superconducting transformer system for the high current test of superconducting cables. The transformer consists of a core-free 10,464 turn primary solenoid which is enclosed by a 6.5 turn secondary. The transformer is designed to deliver a 50 kA dc secondary current at a dc primary current of about 50 A. The secondary current is measured inductively using two toroidal-wound Rogowski coils. The Rogowski coil signal is digitally integrated, resulting in a voltage signal that is proportional to the secondary current. This voltage signal is used to control the secondary current using a feedback loop which automatically compensates for resistive losses in the splices to the superconducting cable samples that are connected to the secondary. The system has been commissioned up to 28 kA secondary current. The reproducibility in the secondary current measurement is better than 0.05% for the relevant current range up to 25 kA. The drift in the secondary current, which results from drift in the digital integrator, is estimated to be below 0.5 A/min. The system's performance is further demonstrated through a voltage-current measurement on a superconducting cable sample at 11 T background magnetic field. The superconducting transformer system enables fast, high resolution, economic, and safe tests of the critical current of superconducting cable samples.

  13. Short-term and long-term Vadose zone monitoring: Current technologies, development, and applications

    Energy Technology Data Exchange (ETDEWEB)

    Faybishenko, Boris

    1999-05-01

    At Hanford, Savannah River, Oak Ridge, Idaho National Engineering and Environmental Laboratory (INEEL), and other DOE sites, field vadose zone observations have shown complex water seepage and mass transport behavior in a highly heterogeneous, thick vadose zone on a variety of scales. Recent investigation showed that severe contamination of soils and groundwater by organic contaminant and nuclear waste occurred because of water seepage and contaminant transport along localized, preferential, fast flow within the heterogeneous vadose zone. However, most of the existing characterization and monitoring methods are not able to locate these localized and persistent preferential pathways associated with specific heterogeneous geologic features, such as clastic dikes, caliche layers, or fractures. In addition, changes in the chemical composition of moving and indigenous solutes, particularly sodium concentration, redox conditions, biological transformation of organic materials, and high temperature, may significantly alter water, chemicals, and bio-transformation exchange between the zones of fast flow and the rest of the media. In this paper, using the data from Hanford and INEEL sites, we will (1) present evidence that central problems of the vadose zone investigations are associated with preferential, fast flow phenomena and accelerated migration of organic and radioactive elements, (2) identify gaps in current characterization and monitoring technologies, and (3) recommend actions for the development of advanced vadose zone characterization and monitoring methods using a combination of hydrologic, geochemical, and geophysical techniques.

  14. Generation of High-Power High-Intensity Short X-Ray Free-Electron-Laser Pulses.

    Science.gov (United States)

    Guetg, Marc W; Lutman, Alberto A; Ding, Yuantao; Maxwell, Timothy J; Decker, Franz-Josef; Bergmann, Uwe; Huang, Zhirong

    2018-01-05

    X-ray free-electron lasers combine a high pulse power, short pulse length, narrow bandwidth, and high degree of transverse coherence. Any increase in the photon pulse power, while shortening the pulse length, will further push the frontier on several key x-ray free-electron laser applications including single-molecule imaging and novel nonlinear x-ray methods. This Letter shows experimental results at the Linac Coherent Light Source raising its maximum power to more than 300% of the current limit while reducing the photon pulse length to 10 fs. This was achieved by minimizing residual transverse-longitudinal centroid beam offsets and beam yaw and by correcting the dispersion when operating over 6 kA peak current with a longitudinally shaped beam.

  15. High-intensity exercise and recovery during short-term ...

    African Journals Online (AJOL)

    There were no significant changes in blood lactate or cortisol concentrations in any group. CRF showed significant decreases (p ≤ 0.05) in fatigue index, muscle pain, and creatine kinase concentration. However, no significant differences were found between groups. Conclusion. Short-term creatine supplementation with or ...

  16. 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.

  17. Cathode erosion in high-current high-pressure arc

    CERN Document Server

    Nemchinsky, V A

    2003-01-01

    Cathode erosion rate was experimentally investigated for two types of arcs: one with tungsten cathode in nitrogen atmosphere and one with hafnium cathode in oxygen atmosphere. Conditions were typical for plasma arc cutting systems: gas pressure from 2 to 5 atm, arc current from 200 to 400 A, gas flow rate from 50 to 130 litre min sup - sup 1. It was found that the actual cathode evaporation rate G is much lower than G sub 0 , the evaporation rate that follows from the Hertz-Knudsen formula: G = nu G sub 0. The difference is because some of the evaporated particles return back to the cathode. For conditions of our experiments, the factor nu could be as low as 0.01. It was shown experimentally that nu depends strongly on the gas flow pattern close to the cathode. In particular, swirling the gas increases nu many times. To explain the influence of gas swirling, model calculations of gas flows were performed. These calculations revealed difference between swirling and non-swirling flows: swirling the gas enhances...

  18. Effect of groove width of modified current collector on internal short circuit of abused lithium-ion battery

    Science.gov (United States)

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

    2017-10-01

    In a lithium-ion battery (LIB), mechanical abuse often leads to internal short circuits (ISC) that trigger thermal runaway. We investigated a thermal-runaway mitigation (TRM) technique using a modified current collector. By generating surface grooves on the current collector, the area of electrodes directly involved in ISC could be largely reduced, which decreased the ISC current. The TRM mechanism took effect immediately after the LIB was damaged. The testing data indicate that the groove width is a critical factor. With optimized groove width, this technique may enable robust and multifunctional design of LIB cells for large-scale energy-storage units.

  19. Renormalization of domain-wall bilinear operators with short-distance current correlators

    Science.gov (United States)

    Tomii, M.; Cossu, G.; Fahy, B.; Fukaya, H.; Hashimoto, S.; Kaneko, T.; Noaki, J.; Jlqcd Collaboration

    2016-09-01

    We determine the renormalization constants for flavor nonsinglet fermion bilinear operators of Möbius domain-wall fermions. The renormalization condition is imposed on the correlation functions in the coordinate space, such that the nonperturbative lattice calculation reproduces the perturbatively calculated counterpart at short distances. The perturbative expansion is precise as the coefficients are available up to O (αs4). We employ 2 +1 -flavor lattice ensembles at three lattice spacings in the range 0.044-0.080 fm.

  20. High performance current controller for particle accelerator magnets supply

    DEFF Research Database (Denmark)

    Maheshwari, Ram Krishan; Bidoggia, Benoit; Munk-Nielsen, Stig

    2013-01-01

    The electromagnets in modern particle accelerators require high performance power supply whose output is required to track the current reference with a very high accuracy (down to 50 ppm). This demands very high bandwidth controller design. A converter based on buck converter topology is used...

  1. Temperature calculations of heat loads in rotating target wheels exposed to high beam currents.

    Energy Technology Data Exchange (ETDEWEB)

    Greene, J. P.; Gabor, R.; Neubauer, J.

    2000-11-29

    In heavy-ion physics, high beam currents can eventually melt or destroy the target. Tightly focused beams on stationary targets of modest melting point will exhibit short lifetimes. Defocused or wobbled beams are employed to enhance target survival. Rotating targets using large diameter wheels can help overcome target melting and allow for higher beam currents to be used in experiments. The purpose of the calculations in this work is to try and predict the safe maximum beam currents which produce heat loads below the melting point of the target material.

  2. A high current density DC magnetohydrodynamic (MHD) micropump

    NARCIS (Netherlands)

    Homsy, Alexandra; Koster, Sander; Hogen-Koster, S.; Eijkel, Jan C.T.; van den Berg, Albert; Lucklum, F.; Verpoorte, E.; de Rooij, Nico F.

    2005-01-01

    This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-µm-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a micromachined

  3. A high current density DC magnetohydrodynamic (MHD) micropump

    NARCIS (Netherlands)

    Homsy, A; Koster, Sander; Eijkel, JCT; van den Berg, A; Lucklum, F; Verpoorte, E; de Rooij, NF

    2005-01-01

    This paper describes the working principle of a DC magnetohydrodynamic (MHD) micropump that can be operated at high DC current densities (J) in 75-mu m-deep microfluidic channels without introducing gas bubbles into the pumping channel. The main design feature for current generation is a

  4. Interrupting Short-Circuit Direct Current Using an AC Circuit Breaker in Series with a Reactor

    Directory of Open Access Journals (Sweden)

    Saurabh Kulkarni

    2012-01-01

    Full Text Available This paper describes and demonstrates the principle and efficacy of a novel direct current fault interruption scheme using a reactor in series with a controlled rectifier and a conventional AC circuit breaker. The presence of the series reactor limits the capacitive discharge current from the DC filter capacitor at the output terminals of the phase-controlled rectifier. In addition, the series reactor along with the filter capacitor forms an underdamped series RLC circuit which forces the fault current to oscillate about zero. This synthetic alternating current can then be interrupted using a conventional AC circuit breaker. The selection criteria for the series reactor and overcurrent protection are presented as well. Using the proposed scheme for an example case, a DC fault current magnitude is reduced from 56 kA to 14 kA, while the interruption time is reduced from 44 ms to 25 ms.

  5. Nonlocal control of electron temperature in short direct current glow discharge plasma

    Energy Technology Data Exchange (ETDEWEB)

    Demidov, V. I. [Department of Optics and Spectroscopy, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); International Laboratory “Nonlocal Plasma in Nanotechnology and Medicine”, ITMO University, Kronverkskiy pr. 49, St. Petersburg 197101 (Russian Federation); Department of Physics and Astronomy, West Virginia University, Morgantown, West Virginia 26506 (United States); Kudryavtsev, A. A.; Stepanova, O. M. [Department of Optics and Spectroscopy, St. Petersburg State University, St. Petersburg 199034 (Russian Federation); Kurlyandskaya, I. P. [International Laboratory “Nonlocal Plasma in Nanotechnology and Medicine”, ITMO University, Kronverkskiy pr. 49, St. Petersburg 197101 (Russian Federation); St. Petersburg University of State Fire Service of EMERCOM RF, Murmansk Branch, Murmansk 183040 (Russian Federation)

    2014-09-15

    To demonstrate controlling the electron temperature in nonlocal plasma, experiments have been performed on a short (without positive column) dc glow discharge with a cold cathode by applying different voltages to the conducting discharge wall. The experiments have been performed for low-pressure noble gas discharges. The applied voltage can modify trapping the energetic electrons emitted from the cathode sheath and arising from the atomic and molecular processes in the plasma within the device volume. This phenomenon results in the energetic electrons heating the slow plasma electrons, which consequently modifies the electron temperature. Furthermore, a numerical model of the discharge has demonstrated the electron temperature modification for the above case.

  6. Short-term herbivory has long-term consequences in warmed and ambient high Arctic tundra

    Science.gov (United States)

    Little, Chelsea J.; Cutting, Helen; Alatalo, Juha; Cooper, Elisabeth

    2017-02-01

    Climate change is occurring across the world, with effects varying by ecosystem and region but already occurring quickly in high-latitude and high-altitude regions. Biotic interactions are important in determining ecosystem response to such changes, but few studies have been long-term in nature, especially in the High Arctic. Mesic tundra plots on Svalbard, Norway, were subjected to grazing at two different intensities by captive Barnacle geese from 2003-2005, in a factorial design with warming by Open Top Chambers. Warming manipulations were continued through 2014, when we measured vegetation structure and composition as well as growth and reproduction of three dominant species in the mesic meadow. Significantly more dead vascular plant material was found in warmed compared to ambient plots, regardless of grazing history, but in contrast to many short-term experiments no difference in the amount of living material was found. This has strong implications for nutrient and carbon cycling and could feed back into community productivity. Dominant species showed increased flowering in warmed plots, especially in those plots where grazing had been applied. However, this added sexual reproduction did not translate to substantial shifts in vegetative cover. Forbs and rushes increased slightly in warmed plots regardless of grazing, while the dominant shrub, Salix polaris, generally declined with effects dependent on grazing, and the evergreen shrub Dryas octopetala declined with previous intensive grazing. There were no treatment effects on community diversity or evenness. Thus despite no changes in total live abundance, a typical short-term response to environmental conditions, we found pronounced changes in dead biomass indicating that tundra ecosystem processes respond to medium- to long-term changes in conditions caused by 12 seasons of summer warming. We suggest that while high arctic tundra plant communities are fairly resistant to current levels of climate warming

  7. Induction and decay of short-term heat acclimation in moderately and highly trained athletes.

    Science.gov (United States)

    Garrett, Andrew T; Rehrer, Nancy J; Patterson, Mark J

    2011-09-01

    A rethinking of current heat-acclimation strategies is required as most research and advice for improving physiological strain in the heat includes maintaining hydration using long-term acclimation protocols (>10 days). Furthermore, these strategies have tended to use untrained and moderately trained participants. Therefore, the aims of this review were to (i) investigate the effectiveness of short-term heat acclimation (STHA) with moderately and highly trained athletes; (ii) determine the importance of fluid regulatory strain, which has a thermally independent role in heat adaptation; (iii) assess the impact of STHA on a marker of thermotolerance (inducible heat-shock protein 70 [HSP70]); and (iv) provide further information on the decay of acclimation to heat. The review suggests that 5-day STHA is effective, and adaptations may be more pronounced after fluid regulatory strain from a dehydration-acclimation regimen. Furthermore, highly trained athletes may have similar physiological gains to those who are less trained using STHA. However, research has tended to focus on untrained or moderately trained participants and more information is required for highly trained populations. HSP70 response is upregulated across STHA. This indicates increased thermotolerance and protective adaptive change that may indicate HSP70 response as a useful marker of heat acclimation. Physiological adaptations after heat acclimation are relatively short term and may vanish only a few days or weeks after removal from heat exposure. From a practical perspective 5-day STHA may be the preferred acclimation regimen for moderately and highly trained athletes as it has been shown to be effective, less expensive and less likely to disrupt the tapering for competition in elite performers. Furthermore, updated information on the time course of acclimation decay may allow a reliable estimate of how long individuals can be free from heat exposure before reacclimation is required. This is

  8. Weed control in short rotation coppice crops: a review of recently published literature and current guidance for farmers

    Energy Technology Data Exchange (ETDEWEB)

    Britt, C.

    2000-07-01

    This review with 41 references is based on a literature review and consultation with experts, and examines the importance of effective weed control. Herbicides currently approved for use in short rotation coppice plantations are listed. Current practices and recommendations to farmers on pre-planting, post-planting, post cut-back, post-harvest, and directed herbicide applications in the growing crop are outlined, and the results of recent research on chemical and mechanical weed control, mulches, and ground cover plants are addressed. Research need relating to weed competition, herbicide evaluation, vegetation management without chemicals, and quantification of post-harvest herbicide applications are identified.

  9. High current test facility for superconductors at Saclay

    CERN Document Server

    Berriaud, C; Vieillard, L

    2001-01-01

    A high DC current (100 kA-design) test facility for superconducting material is under realisation. Aluminum stabilised conductor (as for LHC detectors) can be tested Including the stabiliser in a 4.75 T dipole field of 0.8 m length which can be rotated in both cable perpendicular directions. A superconductor transformer creates the high current with a primary current from -200 A to +200 A. The output power useable is 25 kJ so that junctions between cables or conductors can be measured at high current. Samples, with a cross sections up to 12 mm*30 mm, were 0.8 m long and were equipped with soldered cables of 0.4 m length at both ends. To test different samples without warming the dipole magnet, samples are placed in a separate dewar. The conception design is described and the first results without external dipole magnetic field are reported. (9 refs).

  10. Test set-ups for developing high voltage circuit-breaker for high short-circuit capacities

    Energy Technology Data Exchange (ETDEWEB)

    Patzelt, R.; Ruhnau, W.; Zemann, E.

    1981-10-01

    The increasing short-circuit power in networks requires short-circuit breakers which are capable of interrupting short-circuit currents from 80 to 100 kA. The investigation and research development of a synthetic test circuit according to the principles of voltage- and current-injection respectively for short-circuit currents stated above comprises the first part of this report. The second part deals with the influence of Ferrum in the magnetic circuit on the transient recovery voltage wave form which is not influenced by the arc voltage. Investigations on the measurement of the post-arc current is described in the third chapter. In this case the construction and measurement of meshed grid- and tube shunts represent the major constituent. The fourth and last chapter deals with the investigation of synthetic test circuits in order to prove the capacitive switching capabilities of circuit-breakers. Two different switching circuits were subjected to test and subsequently developed for service.

  11. Short pulse mid-infrared amplifier for high average power

    CSIR Research Space (South Africa)

    Botha, LR

    2006-09-01

    Full Text Available High pressure CO 2 lasers are good candidates for amplifying picosecond mid infrared pulses. High pressure CO 2 lasers are notorious for being unreliable and difficult to operate. In this paper a high pressure CO 2 laser is presented based on well...

  12. Design studies of a high-current radiofrequency quadrupole for ...

    Indian Academy of Sciences (India)

    employing the adiabatic bunching process. This process increases the capture effi- ciency of the RFQ to nearly 100%. Because of their high capture efficiency at low energies, the RFQs suite well as a first unit of high-current RF linear accelerators in many advanced applications, such as production of radioactive ion beams ...

  13. Management system to a photovoltaic panel based on the measurement of short-circuit currents

    Science.gov (United States)

    Dordescu, M.

    2016-12-01

    This article is devoted to fundamental issues arising from operation in terms of increased energy efficiency for photovoltaic panel (PV). By measuring the current from functioning cage determine the current value prescribed amount corresponding to maximum power point results obtained by requiring proof of pregnancy with this method are the maximum energy possible, thus justifying the usefulness of this process very simple and inexpensive to implement in practice. The proposed adjustment method is much simpler and more economical than conventional methods that rely on measuring power cut.

  14. Transmission Level High Temperature Superconducting Fault Current Limiter

    Energy Technology Data Exchange (ETDEWEB)

    Stewart, Gary [SuperPower, Inc., Schenectady, NY (United States)

    2016-10-05

    The primary objective of this project was to demonstrate the feasibility and reliability of utilizing high-temperature superconducting (HTS) materials in a Transmission Level Superconducting Fault Current Limiter (SFCL) application. During the project, the type of high-temperature superconducting material used evolved from 1st generation (1G) BSCCO-2212 melt cast bulk high-temperature superconductors to 2nd generation (2G) YBCO-based high-temperature superconducting tape. The SFCL employed SuperPower's “Matrix” technology, that offers modular features to enable scale up to transmission voltage levels. The SFCL consists of individual modules that contain elements and parallel inductors that assist in carrying the current during the fault. A number of these modules are arranged in an m x n array to form the current-limiting matrix.

  15. High-voltage, high-current, solid-state closing switch

    Energy Technology Data Exchange (ETDEWEB)

    Focia, Ronald Jeffrey

    2017-08-22

    A high-voltage, high-current, solid-state closing switch uses a field-effect transistor (e.g., a MOSFET) to trigger a high-voltage stack of thyristors. The switch can have a high hold-off voltage, high current carrying capacity, and high time-rate-of-change of current, di/dt. The fast closing switch can be used in pulsed power applications.

  16. High-current pulses from inductive energy stores

    Science.gov (United States)

    Wipf, S. L.

    1981-11-01

    Superconducting inductive energy stores can be used for high power pulse supplies if a suitable current multiplication scheme is used. The concept of an inductive Marx generator is superior to a transformer. A third scheme, a variable flux linkage device, is suggested; in multiplying current it also compresses energy. Its function is in many ways analogous to that of a horsewhip. Superconductor limits indicate that peak power levels of TW can be reached for stored energies above 1 MJ.

  17. Solid Oxide Electrolysis Cells: Degradation at High Current Densities

    DEFF Research Database (Denmark)

    Knibbe, Ruth; Traulsen, Marie Lund; Hauch, Anne

    2010-01-01

    The degradation of Ni/yttria-stabilized zirconia (YSZ)-based solid oxide electrolysis cells operated at high current densities was studied. The degradation was examined at 850°C, at current densities of −1.0, −1.5, and −2.0 A/cm2, with a 50:50 (H2O:H2) gas supplied to the Ni/YSZ hydrogen electrode...

  18. 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.

  19. Microstructures and critical currents in high-{Tc} superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Suenaga, Masaki

    1998-11-01

    Microstructural defects are the primary determining factors for the values of critical-current densities in a high {Tc} superconductor after the electronic anisotropy along the a-b plane and the c-direction. A review is made to assess firstly what would be the maximum achievable critical-current density in YBa{sub 2}Cu{sub 3}O{sub 7} if nearly ideal pinning sites were introduced and secondly what types of pinning defects are currently introduced or exist in YBa{sub 2}Cu{sub 3}O{sub 7} and how effective are these in pinning vortices.

  20. Discharge current modes of high power impulse magnetron sputtering

    Directory of Open Access Journals (Sweden)

    Zhongzhen Wu

    2015-09-01

    Full Text Available Based on the production and disappearance of ions and electrons in the high power impulse magnetron sputtering plasma near the target, the expression of the discharge current is derived. Depending on the slope, six possible modes are deduced for the discharge current and the feasibility of each mode is discussed. The discharge parameters and target properties are simplified into the discharge voltage, sputtering yield, and ionization energy which mainly affect the discharge plasma. The relationship between these factors and the discharge current modes is also investigated.

  1. Short-lived climate forcers from current shipping and petroleum activities in the Arctic

    Directory of Open Access Journals (Sweden)

    K. Ødemark

    2012-02-01

    Full Text Available Emissions of short-lived climate forcers (SLCF in the Arctic region are expected to increase, notably from shipping and petroleum extraction. We here discuss changes in atmospheric SLCF concentrations and resulting radiative forcing (RF from present day shipping and petroleum activities in the Arctic. The three-dimensional chemistry transport OsloCTM2 and a state of the art radiative forcing model are used, based on a coherent dataset of present day Arctic emissions. We find that the net RF of SLCF of shipping in the Arctic region is negative, mainly due to the direct and indirect RF effects of sulphate emissions, while the net RF of SLCF of petroleum extraction is positive, mainly due to the effects of black carbon aerosols in the air and deposited on snow. Strong seasonal variations of the sensitivities to emissions are found. In terms of annual mean values we find that the Arctic sensitivities to SLCF is similar to global average sensitivities. One exception to this is the stronger snow/ice albedo effect from BC emissions.

  2. Short ragweeds is highly cross-reactive with other ragweeds.

    Science.gov (United States)

    Christensen, Lars H; Ipsen, Henrik; Nolte, Hendrik; Maloney, Jennifer; Nelson, Harold S; Weber, Richard; Lund, Kaare

    2015-12-01

    The most widespread ragweed (Ambrosia) species in North America are short ragweed (Ambrosia artemisiifolia; Amb a), giant ragweed (Ambrosia trifida; Amb t), and western ragweed (Ambrosia psilostachya; Amb p). Varied geographic distributions of ragweed species raise questions regarding the need for ragweed species-specific allergen immunotherapy. To determine allergenic cross-reactivity among ragweed species by immunologic analyses of sera from subjects allergic to ragweed from North America and Europe. Sera were collected from 452 subjects allergic to ragweed who participated in Amb a sublingual immunotherapy tablet clinical trials. All subjects had positive skin prick test and serum IgE against Amb a. Ragweed-specific IgE (pre treatment) and IgG4 (post treatment) were measured by ImmunoCAP. IgE inhibition studies among Amb a, Amb t, and Amb p were conducted. Using pooled sera from another ragweed-allergic population, IgE inhibition studies of 7 less widespread Ambrosia species also were conducted. A strong correlation between Amb a vs Amb p and Amb t serum IgE levels was observed. In the vast majority of pretreatment sera, Amb a inhibited Amb a, Amb p, and Amb t IgE reactivity by more than 90%. Strong correlations were observed between Amb a vs Amb p and Amb t post-treatment IgG4 levels. In pooled sera, Amb a extract inhibited the binding of serum IgE to all 10 ragweed species by 98%-100%. In a population of subjects allergic to Amb a, substantial allergenic cross-reactivity among Amb a, Amb p, and Amb t was demonstrated. These in vitro data suggest that an Amb a-based single-species ragweed allergen immunotherapy may be therapeutically active in patients exposed to diverse ragweed pollens. Clinicaltrials.gov, NCT00770315, NCT00783198, and NCT00330083. Copyright © 2015 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.

  3. Generation of high current, long duration rectangular pulses

    CERN Document Server

    Faugeras, Paul E; Zanasco, J P

    1973-01-01

    The excitation of the fast pulsed kicker magnets foreseen for the CERN 400 GeV proton synchrotron requires rectangular pulses with a current amplitude of 3000 A to 10000 A, a pulse duration adjustable between 1 and 24 mu sec, and short rise and fall times. These pulses are generated by a LC ladder network discharged with fast switches. Several kinds of switches have been tested: multigap thyratrons of standard design, a composite switch called 'thyragnitron' and made of a normal thyratron by-passed ignitrons, and finally special thyratrons with a second cathode assembly in place of the usual anode. Experimental pulse shapes and results of life tests for these different switches are presented and discussed. (8 refs).

  4. High-current cyclotron to drive an electronuclear assembly

    CERN Document Server

    Alenitsky, Yu G

    2002-01-01

    The proposal on creation of a high-current cyclotron complex for driving an electronuclear assembly reported at the 17th Meeting on Accelerators of Charged Particles is discussed. Some changes in the basic design parameters of the accelerator are considered in view of new results obtained in the recent works. It is shown that the cyclotron complex is now the most real and cheapest accelerator for production of proton beams with a power of up to 10 MW. Projects on design of a high-current cyclotron complex for driving an electronuclear subcritical assembly are presented.

  5. Short-Term Hypocaloric High-Fiber and High-Protein Diet Improves Hepatic Steatosis Assessed by Controlled Attenuation Parameter.

    Science.gov (United States)

    Arslanow, Anita; Teutsch, Melanie; Walle, Hardy; Grünhage, Frank; Lammert, Frank; Stokes, Caroline S

    2016-06-16

    Non-alcoholic fatty liver disease is one of the most prevalent liver diseases and increases the risk of fibrosis and cirrhosis. Current standard treatment focuses on lifestyle interventions. The primary aim of this study was to assess the effects of a short-term low-calorie diet on hepatic steatosis, using the controlled attenuation parameter (CAP) as quantitative tool. In this prospective observational study, 60 patients with hepatic steatosis were monitored during a hypocaloric high-fiber, high-protein diet containing 1,000 kcal/day. At baseline and after 14 days, we measured hepatic fat contents using CAP during transient elastography, body composition with bioelectrical impedance analysis, and serum liver function tests and lipid profiles using standard clinical-chemical assays. The median age was 56 years (25-78 years); 51.7% were women and median body mass index was 31.9 kg/m(2) (22.4-44.8 kg/m(2)). After 14 days, a significant CAP reduction (14.0%; PCAP improvements occur after only 14 days on short-term low-calorie diet, together with reductions of body composition parameters, serum lipids, and liver enzymes, pointing to the dynamics of hepatic lipid turnover.

  6. Pharmacological modulation of the short-lasting effects of antagonistic direct current-stimulation over the human motor cortex

    Directory of Open Access Journals (Sweden)

    Leila eChaieb

    2012-07-01

    Full Text Available Combined administration of transcranial direct current stimulation (tDCS with either pergolide (PGL or D-cycloserine (D-CYC can prolong the excitability-diminishing effects of cathodal, or the excitability enhancing effect of anodal stimulation for up to 24hrs poststimulation. However, it remains unclear whether the potentiation of the observed aftereffects is dominated by the polarity and duration of the stimulation, or the dual application of combined stimulation and drug administration. The present study looks at whether the aftereffects of oral administration of PGL (a D1/D2 agonist or D-CYC (a partial NMDA receptor agonist, in conjunction with the short duration antagonistic application of tDCS (either 5 min cathodal followed immediately by 5 min anodal or vice versa, that alone only induces short lasting aftereffects, can modulate cortical excitability in healthy human subjects, as revealed by a single-pulse MEP (motor-evoked-potential paradigm. Results indicate that the antagonistic application of DC currents induces short-term neuroplastic aftereffects that are dependent upon the polarity of the second application of short-duration tDCS. The application of D-cycloserine resulted in a reversal of this trend and so consequently a marked inhibition of cortical excitability with the cathodal-anodal stimulation order was observed. The administration of pergolide showed no significant aftereffects in either case. These results emphasise that the aftereffects of tDCS are dependent upon the stimulation orientation, and mirror the findings of other studies reporting the neuroplasticity inducing aftereffects of tDCS, and their prolongation when combined with the administration of CNS active drugs.

  7. The Brief RCOPE: Current Psychometric Status of a Short Measure of Religious Coping

    Directory of Open Access Journals (Sweden)

    Kenneth Pargament

    2011-02-01

    Full Text Available The Brief RCOPE is a 14-item measure of religious coping with major life stressors. As the most commonly used measure of religious coping in the literature, it has helped contribute to the growth of knowledge about the roles religion serves in the process of dealing with crisis, trauma, and transition. This paper reports on the development of the Brief RCOPE and its psychometric status. The scale developed out of Pargament’s (1997 program of theory and research on religious coping. The items themselves were generated through interviews with people experiencing major life stressors. Two overarching forms of religious coping, positive and negative, were articulated through factor analysis of the full RCOPE. Positive religious coping methods reflect a secure relationship with a transcendent force, a sense of spiritual connectedness with others, and a benevolent world view. Negative religious coping methods reflect underlying spiritual tensions and struggles within oneself, with others, and with the divine. Empirical studies document the internal consistency of the positive and negative subscales of the Brief RCOPE. Moreover, empirical studies provide support for the construct validity, predictive validity, and incremental validity of the subscales. The Negative Religious Coping subscale, in particular, has emerged as a robust predictor of health-related outcomes. Initial evidence suggests that the Brief RCOPE may be useful as an evaluative tool that is sensitive to the effects of psychological interventions. In short, the Brief RCOPE has demonstrated its utility as an instrument for research and practice in the psychology of religion and spirituality.

  8. HIGH-CURRENT ERL-BASED ELECTRON COOLING FOR RHIC.

    Energy Technology Data Exchange (ETDEWEB)

    BEN-ZVI, I.

    2005-09-18

    The design of an electron cooler must take into account both electron beam dynamics issues as well as the electron cooling physics. Research towards high-energy electron cooling of RHIC is in its 3rd year at Brookhaven National Laboratory. The luminosity upgrade of RHIC calls for electron cooling of various stored ion beams, such as 100 GeV/A gold ions at collision energies. The necessary electron energy of 54 MeV is clearly out of reach for DC accelerator system of any kind. The high energy also necessitates a bunched beam, with a high electron bunch charge, low emittance and small energy spread. The Collider-Accelerator Department adopted the Energy Recovery Linac (ERL) for generating the high-current, high-energy and high-quality electron beam. The RHIC electron cooler ERL will use four Superconducting RF (SRF) 5-cell cavities, designed to operate at ampere-class average currents with high bunch charges. The electron source will be a superconducting, 705.75 MHz laser-photocathode RF gun, followed up by a superconducting Energy Recovery Linac (ERL). An R&D ERL is under construction to demonstrate the ERL at the unprecedented average current of 0.5 amperes. Beam dynamics performance and luminosity enhancement are described for the case of magnetized and non-magnetized electron cooling of RHIC.

  9. Rf Gun with High-Current Density Field Emission Cathode

    Energy Technology Data Exchange (ETDEWEB)

    Jay L. Hirshfield

    2005-12-19

    High current-density field emission from an array of carbon nanotubes, with field-emission-transistor control, and with secondary electron channel multiplication in a ceramic facing structure, have been combined in a cold cathode for rf guns and diode guns. Electrodynamic and space-charge flow simulations were conducted to specify the cathode configuration and range of emission current density from the field emission cold cathode. Design of this cathode has been made for installation and testing in an existing S-band 2-1/2 cell rf gun. With emission control and modulation, and with current density in the range of 0.1-1 kA/cm2, this cathode could provide performance and long-life not enjoyed by other currently-available cathodes

  10. High current gain silicon-based spin transistor

    CERN Document Server

    Dennis, C L; Ensell, G J; Gregg, J F; Thompson, S M

    2003-01-01

    A silicon-based spin transistor of novel operating principle has been demonstrated in which the current gain at room temperature is 1.4 (n-type) and 0.97 (p-type). This high current gain was obtained from a hybrid metal/semiconductor analogue to the bipolar junction transistor which functions by tunnel-injecting carriers from a ferromagnetic emitter into a diffusion driven silicon base and then tunnel-collecting them via a ferromagnetic collector. The switching of the magnetic state of the collector ferromagnet controls the collector efficiency and the current gain. Furthermore, the magnetocurrent, which is determined to be 98% (140%) for p-type (n-type) in -110 Oe, is attributable to the spin-polarized base diffusion current.

  11. Birkeland current effects on high-latitude groundmagnetic field perturbations

    CERN Document Server

    Laundal, K M; Lehtinen, N; Gjerloev, J W; Østgaard, N; Tenfjord, P; Reistad, J P; Snekvik, K; Milan, S E; Ohtani, S; Anderson, B J

    2016-01-01

    Magnetic perturbations on ground at high latitudes are directly associated only with the divergence-free component of the height-integrated horizontal ionospheric current, $\\textbf{J}_{\\perp,df}$. Here we show how $\\textbf{J}_{\\perp,df}$ can be expressed as the total horizontal current $\\textbf{J}_\\perp$ minus its curl-free component, the latter being completely determined by the global Birkeland current pattern. Thus in regions where $\\textbf{J}_\\perp = 0$, the global Birkeland current distribution alone determines the local magnetic perturbation. We show with observations from ground and space that in the polar cap, the ground magnetic field perturbations tend to align with the Birkeland current contribution in darkness but not in sunlight. We also show that in sunlight, the magnetic perturbations are typically such that the equivalent overhead current is anti-parallel to the convection, indicating that the Hall current system dominates. Thus the ground magnetic field in the polar cap relates to different c...

  12. High-quality lossy compression: current and future trends

    Science.gov (United States)

    McLaughlin, Steven W.

    1995-01-01

    This paper is concerned with current and future trends in the lossy compression of real sources such as imagery, video, speech and music. We put all lossy compression schemes into common framework where each can be characterized in terms of three well-defined advantages: cell shape, region shape and memory advantages. We concentrate on image compression and discuss how new entropy constrained trellis-based compressors achieve cell- shape, region-shape and memory gain resulting in high fidelity and high compression.

  13. SHORT OVERVIEW OF CLINICAL TRIALS WITH CURRENT IMMUNOTHERAPEUTIC TOOLS FOR CANCER TREATMENT

    Directory of Open Access Journals (Sweden)

    T. S. Nepomnyashchikh

    2017-01-01

    Full Text Available Over last decade, a substantial progress has been made, with respect to understanding of cancer biology and its interplay with the host immune system. Different immunotherapeutic drugs based on recombinant cytokines and monoclonal antibodies are widely used in cancer therapy, and a large number of experimental cancer treatments have been developed, many of which are currently undergoing various stages of clinical trials. Recent endorsement of a recombinant oncolytic herpesvirus T-VEC for the treatment of melanoma was an important step towards a more safe and efficient anticancer therapeutics. In this review, we shall mention only some of the most promising cancer immunotherapy strategies, namely, immune checkpoint inhibitors, cellular therapy and oncolytic viruses. 

  14. West India coastal current and Lakshadweep High/Low

    Digital Repository Service at National Institute of Oceanography (India)

    Shetye, S.R.

    , the West India Coastal Current is a superposition of annual and semiannual coastally-trapped Kelvin waves. The Lakshadweep High/Low forms when the Kelvin waves, on turning around Sri Lanka, and propagating northward along the west coast of India, radiate...

  15. Bottom mounted seabed mooring frame for high current field

    Digital Repository Service at National Institute of Oceanography (India)

    AshokKumar, K.; Chandramohan, P.; Pednekar, P.S.; Diwan, S.G.

    and direction on the sea surface and at a fixed five layers. The company supplied frame was not suitable to use at the proposed measurement location, owing to random oscillation in the seabed, strong currents and high concentration of sediments in the water...

  16. Observed currents at Bombay High during a winter

    Digital Repository Service at National Institute of Oceanography (India)

    Fernandes, A.A; Chandramohan, P.; Nayak, B.U.

    Ten day records of Aanderaa current meters (24 Dec 1981 to 2 Jan. 1982) at four depths, viz. 30, 45, 60 and 75 m at Bombay High (19˚24.5'N, 71˚2.5'E) off the west coast of India, in a water depth of 80 m have been subjected to spectral, cross...

  17. Design studies of a high-current radiofrequency quadrupole for ...

    Indian Academy of Sciences (India)

    Home; Journals; Pramana – Journal of Physics; Volume 74; Issue 2. Design studies of a high-current radiofrequency quadrupole for accelerator-driven systems programme ... We have followed the conventional design technique with slight modifications and compared that with the equipartitioned (EP) type of design.

  18. Origin of the light intensity dependence of the short-circuit current of polymer/fullerene solar cells

    OpenAIRE

    Koster, LJA; Mihailetchi, VD; Xie, H.; Blom, PWM

    2005-01-01

    A typical feature of polymer/fullerene based solar cells is that the current density under short-circuit conditions (J(sc)) does not scale exactly linearly with light intensity (I). Instead, a power law relationship is found given by J(sc)proportional to I-alpha, where alpha ranges from 0.85 to 1. In a number of reports this deviation from unity is speculated to arise from the occurrence of bimolecular recombination. We demonstrate that the dependence of the photocurrent in bulk heterojunctio...

  19. Influence of short-term solar disturbances on the fair weather conduction current

    Directory of Open Access Journals (Sweden)

    Elhalel Gal

    2014-01-01

    Full Text Available The fair weather atmospheric electrical current (Jz couples the ionosphere to the lower atmosphere and thus provides a route by which changes in solar activity can modify processes in the lower troposphere. This paper examines the temporal variations and spectral characteristics of continuous measurements of Jz conducted at the Wise Observatory in Mitzpe-Ramon, Israel (30°35′ N, 34°45′ E, during two large CMEs, and during periods of increased solar wind density. Evidence is presented for the effects of geomagnetic storms and sub-storms on low latitude Jz during two coronal mass ejections (CMEs, on 24–25th October 2011 and 7–8th March 2012, when the variability in Jz increased by an order of magnitude compared to normal fair weather conditions. The dynamic spectrum of the increased Jz fluctuations exhibit peaks in the Pc5 frequency range. Similar low frequency characteristics occur during periods of enhanced solar wind proton density. During the October 2011 event, the periods of increased fluctuations in Jz lasted for 7 h and coincided with fluctuations of the inter-planetary magnetic field (IMF detected by the ACE satellite. We suggest downward mapping of ionospheric electric fields as a possible mechanism for the increased fluctuations.

  20. Transient analysis and burnout of high temperature superconducting current leads

    Science.gov (United States)

    Seol, S. Y.; Hull, J. R.

    The transient behaviour of high-temperature superconductor (HTS) current leads operated between liquid helium and liquid nitrogen temperatures is analysed for burnout conditions upon transition of the HTS into the normal state. Leads composed of HTS only and of HTS sheathed by pure silver or silver alloy are investigated numerically for temperature-dependent properties and analytically for temperature-independent properties. For lower values of shape factor (current density times length), the lead can be operated indefinitely without burnout. At higher values of shape factor, the lead reaches burnout in a finite time. With high current densities, the leads heat adiabatically. For a fixed shape factor, low current densities are desired to achieve long burnout times. To achieve a low helium boil-off rate in the superconducting state without danger of burnout, there is a preferred temperature dependence for thermal conductivity, and silver alloy sheaths are preferred to pure silver sheaths. However, for a given current density, pure silver sheaths take longer to burn out.

  1. Where current pharmacological therapies fall short in COPD: symptom control is not enough

    Directory of Open Access Journals (Sweden)

    N. Roche

    2007-09-01

    Full Text Available Chronic obstructive pulmonary disease (COPD is a common and progressive condition that is currently the fourth leading cause of death worldwide. There is now a large body of evidence indicating that both pulmonary and systemic inflammation are present in patients with stable COPD and may underlie both respiratory symptoms and common comorbidities of this disease. Smoking cessation and long-term oxygen therapy have been shown to change the course of COPD and recent results obtained with the combination of fluticasone and salmeterol have indicated that it could decrease mortality and slow the decline in lung function in patients with this disease. However, some pharmacological treatments can significantly improve dyspnoea, exercise tolerance, limitations in activity, rate of exacerbations and quality of life (e.g. long-acting bronchodilators and inhaled corticosteroids combined with a long-acting beta2-agonist. The ability of these agents to modify the rate of disease progression remains to be firmly established in large-scale, long-term trials. The concept of disease modification itself in COPD may need to be revisited and more precisely defined in terms of markers and clinical outcomes, including extrarespiratory manifestations: agents that durably affect symptoms, activities, exacerbations and quality of life should probably be considered as disease modifiers. It is also reasonable to suggest that early diagnosis and treatment of patients with COPD might be the first and potentially most important disease-modifying intervention. There is clearly a need for new therapies that directly target the specific inflammatory processes underlying chronic obstructive pulmonary disease and its pulmonary and extrapulmonary manifestations.

  2. Spot-welding solid targets for high current cyclotron irradiation

    Science.gov (United States)

    Ellison, Paul A.; Valdovinos, Hector F.; Graves, Stephen A.; Barnhart, Todd E.; Nickles, Robert J.

    2016-01-01

    Zirconium-89 finds broad application for use in positron emission tomography. Its cyclotron production has been limited by the heat transfer from yttrium targets at high beam currents. A spot welding technique allows a three-fold increase in beam current, without affecting 89Zr quality. An yttrium foil, welded to a jet-cooled tantalum support base accommodates a 50 μA proton beam degraded to 14 MeV. The resulting activity yield of 48 ± 4 MBq/(μA·hr) now extends the outreach of 89Zr for a broader distribution. PMID:27771445

  3. Simulation of high currents in x-ray flash tubes

    Science.gov (United States)

    Germer, R.; Sato, E.

    2008-11-01

    The discharge in linear plasma X-ray flash tubes ( Sato tubes ) is simulated. For the geometry of a cylinder cathode outside and an anode in the centre, the electrical fields and potentials are calculated and the propagation of electrons are studied. Space charge limits the current in the initial phase strongly. Replacing the vacuum by plasma from the anode evaporation, it is possible to get increasing current and strong X-ray pulses. Space charge is important for the high intensity X-ray production up to the end of the emission.

  4. Short and long duration transcranial direct current stimulation (tDCS) over the human hand motor area.

    Science.gov (United States)

    Furubayashi, Toshiaki; Terao, Yasuo; Arai, Noritoshi; Okabe, Shingo; Mochizuki, Hitoshi; Hanajima, Ritsuko; Hamada, Masashi; Yugeta, Akihiro; Inomata-Terada, Satomi; Ugawa, Yoshikazu

    2008-02-01

    The aim of the present paper is to study effects of short and long duration transcranial direct current stimulation (tDCS) on the human motor cortex. In eight normal volunteers, motor evoked potentials (MEPs) induced by transcranial magnetic stimulation (TMS) were recorded from the right first dorsal interosseous muscle, and tDCS was given with electrodes over the left primary motor cortex (M1) and the contralateral orbit. We performed two experiments: one for short duration tDCS (100 ms, 1, 3 or 5 mA) and the other for long duration tDCS (10 min, 1 mA). The stimulus onset asynchrony (SOA) between the onset of tDCS and TMS were 1-7 and 10-120 ms for the former experiment. In the latter experiment, TMS was given 0-20 min after the end of 10 min tDCS. We evaluated the effect of tDCS on the motor cortex by comparing MEPs conditioned by tDCS with control MEPs. Cathodal short duration tDCS significantly reduced the size of responses to motor cortical stimulation at SOAs of 1-7 ms when the intensity was equal to or greater than 3 mA. Anodal short duration tDCS significantly increased MEPs when the intensity was 3 mA, but the enhancement did not occur when using 5 mA conditioning stimulus. Moreover, both anodal and cathodal short duration tDCS decreased responses to TMS significantly at SOAs of 20-50 ms and enhanced them at an SOA of 90 ms. Long duration cathodal tDCS decreased MEPs at 0 and 5 min after the offset of tDCS and anodal long duration tDCS increased them at 1 and 15 min. We conclude that the effect at SOAs less than 10 ms is mainly caused by acute changes in resting membrane potential induced by tDCS. The effect at SOAs of 20-100 ms is considered to be a nonspecific effect of a startle-like response produced by activation of skin sensation at the scalp. The effect provoked by long duration tDCS may be short-term potentiation or depression like effects.

  5. PRINCIPLES OF IMPLEMENTATION OF CURRENT PROTECTION FROM INTERPHASE SHORT-CIRCUITS ON THE POWER LINES WITH UNILATERAL FEED

    Directory of Open Access Journals (Sweden)

    F. A. Romaniuk

    2015-01-01

    Full Text Available The article describes the implementation of the principle of overcurrent protection from interphase  short-circuits  on  the  power  lines  with  unilateral  feed.  The  expression  of  the detection of the fault location by the relative value of the distance from the installation of pro- tection to the point of damage with the help of the results of operational control of the short- circuit current damaged phases has been suggested in the article. Also the expression for determining  the  time  delay response  for  such  protection  has been  presented,  taking  into account fault location that had been detected.The paper proposes and describes the functional diagram of the overcurrent protection in detail, provides realization of the implementation of the principles set out in the article. Paper content includes the description of the elements of the considered overcurrent protection, such as input current transducers connected to the measuring current transformers of the protected line, maxiselector, miniselector, block of the determination of the mode type, the measuring unit with the setting unit, detecting fault location unit with the setting unit, calculation unit and control unit with time delay parameter setting, an OR gate, the actuating element, that opens circuit breaker of the protected line. The operation of the proposed scheme is reviewed in  the  article.  All  units  and  elements  of functional  circuit overcurrent protection  can  be implemented with the help of analog and digital technology. Modern microprocessors can be used for these purposes.The efficiency of provided implementation of the principles of overcurrent protection from phase-to-phase short circuits on the power lines with unilateral feed was studied by computational experiments. These results confirm the effectiveness of the proposed solutions and also trip of short-circuit within the main zone line protection is provided without

  6. High drug-loading nanomedicines: progress, current status, and prospects.

    Science.gov (United States)

    Shen, Shihong; Wu, Youshen; Liu, Yongchun; Wu, Daocheng

    2017-01-01

    Drug molecules transformed into nanoparticles or endowed with nanostructures with or without the aid of carrier materials are referred to as "nanomedicines" and can overcome some inherent drawbacks of free drugs, such as poor water solubility, high drug dosage, and short drug half-life in vivo. However, most of the existing nanomedicines possess the drawback of low drug-loading (generally less than 10%) associated with more carrier materials. For intravenous administration, the extensive use of carrier materials might cause systemic toxicity and impose an extra burden of degradation, metabolism, and excretion of the materials for patients. Therefore, on the premise of guaranteeing therapeutic effect and function, reducing or avoiding the use of carrier materials is a promising alternative approach to solve these problems. Recently, high drug-loading nanomedicines, which have a drug-loading content higher than 10%, are attracting increasing interest. According to the fabrication strategies of nanomedicines, high drug-loading nanomedicines are divided into four main classes: nanomedicines with inert porous material as carrier, nanomedicines with drug as part of carrier, carrier-free nanomedicines, and nanomedicines following niche and complex strategies. To date, most of the existing high drug-loading nanomedicines belong to the first class, and few research studies have focused on other classes. In this review, we investigate the research status of high drug-loading nanomedicines and discuss the features of their fabrication strategies and optimum proposal in detail. We also point out deficiencies and developing direction of high drug-loading nanomedicines. We envision that high drug-loading nanomedicines will occupy an important position in the field of drug-delivery systems, and hope that novel perspectives will be proposed for the development of high drug-loading nanomedicines.

  7. PV source based high voltage gain current fed converter

    Science.gov (United States)

    Saha, Soumya; Poddar, Sahityika; Chimonyo, Kudzai B.; Arunkumar, G.; Elangovan, D.

    2017-11-01

    This work involves designing and simulation of a PV source based high voltage gain, current fed converter. It deals with an isolated DC-DC converter which utilizes boost converter topology. The proposed converter is capable of high voltage gain and above all have very high efficiency levels as proved by the simulation results. The project intends to produce an output of 800 V dc from a 48 V dc input. The simulation results obtained from PSIM application interface were used to analyze the performance of the proposed converter. Transformer used in the circuit steps up the voltage as well as to provide electrical isolation between the low voltage and high voltage side. Since the converter involves high switching frequency of 100 kHz, ultrafast recovery diodes are employed in the circuitry. The major application of the project is for future modeling of solar powered electric hybrid cars.

  8. Electronic Current Transducer (ECT) for high voltage dc lines

    Science.gov (United States)

    Houston, J. M.; Peters, P. H., Jr.; Summerayes, H. R., Jr.; Carlson, G. J.; Itani, A. M.

    1980-02-01

    The development of a bipolar electronic current transducer (ECT) for measuring the current in a high voltage dc (HVDC) power line at line potential is discussed. The design and construction of a free standing ECT for use on a 400 kV line having a nominal line current of 2000 A is described. Line current is measured by a 0.0001 ohm shunt whose voltage output is sampled by a 14 bit digital data link. The high voltage interface between line and ground is traversed by optical fibers which carry digital light signals as far as 300 m to a control room where the digital signal is converted back to an analog representation of the shunt voltage. Two redundant electronic and optical data links are used in the prototype. Power to operate digital and optical electronics and temperature controlling heaters at the line is supplied by a resistively and capacitively graded 10 stage cascade of ferrite core transformers located inside the hollow, SF6 filled, porcelain support insulator. The cascade is driven by a silicon controlled rectifier inverter which supplies about 100 W of power at 30 kHz.

  9. High School Sport Specialization Patterns of Current Division I Athletes.

    Science.gov (United States)

    Post, Eric G; Thein-Nissenbaum, Jill M; Stiffler, Mikel R; Brooks, M Alison; Bell, David R; Sanfilippo, Jennifer L; Trigsted, Stephanie M; Heiderscheit, Bryan C; McGuine, Timothy A

    Sport specialization is a strategy to acquire superior sport performance in 1 sport but is associated with increased injury risk. Currently, the degree of high school specialization among Division I athletes is unknown. College athletes will display increased rates of specialization as they progress through their high school careers. Descriptive epidemiological study. Level 4. Three hundred forty-three athletes (115 female) representing 9 sports from a Midwest Division I University completed a previously utilized sport specialization questionnaire regarding sport participation patterns for each grade of high school. McNemar and chi-square tests were used to investigate associations of grade, sport, and sex with prevalence of sport specialization category (low, moderate, high) (a priori P ≤ 0.05). Specialization increased throughout high school, with 16.9% (n = 58) and 41.1% (n = 141) of athletes highly specialized in 9th and 12th grades, respectively. Football athletes were less likely to be highly specialized than nonfootball athletes for each year of high school ( P 0.23). The majority of Division I athletes were not classified as highly specialized throughout high school, but the prevalence of high specialization increased as athletes progressed through high school. Nonfootball athletes were more likely to be highly specialized than football athletes at each grade level. Most athletes who are recruited to participate in collegiate athletics will eventually specialize in their sport, but it does not appear that early specialization is necessary to become a Division I athlete. Athletes should be counseled regarding safe participation in sport during high school to minimize injury and maximize performance.

  10. A short review of the previous and current epidemiological situation of schistosomiasis in China

    Directory of Open Access Journals (Sweden)

    Li-Ping Cen

    1997-02-01

    Full Text Available Schistosomiasis japonica has long been endemic in the People's Republic of China. In the 1950s, the number of the infected persons was estimated at 10 million; infected snail habitats were estimated at more than 14 billion square metres and infected cattle at 1.2 million. After schistosomiasis control measures were carried out, it was a great success. According to the survey of 1989, infected persons were estimated at 0.95 million; infected snails at 3.47 billion and infected cattle at about 0.1 million.These results compared with those of the 1950s show big reductions in prevalence rates 90.5%, 75.2% and 91.6%, respectively. At present, the disease is a threat in the marshland and lake regions and the high mountainous regions. To maintain the success achieved in effective control and to bring the yet endemic marshland and lake regions and mountainous areas under control are hard and long-term tasks confronting the People's Republic of China.A esquistossomose japonica, há séculos, é considerada endêmica na República Popular da China. Em 1950, estimou-se em 10 milhões o número de pessoas infectadas; focos de caramujos infectados ocupavam 14 bilhões de metros quadrados e era de 1,2 milhões o número de gado infectado. As medidas de controle da esquistossomose alcançaram grande sucesso. De acordo com o levantamento realizado em 1989, o número de pessoas infectadas decresceu para 950 mil, focos de caramujos infectados ocupavam 3,47 bilhões de metros quadrados e o número de gado contaminado passou a 100 mil. Estes resultados, quando comparados ao de 1950, mostraram grande redução, sendo de respectivamente, 90,5%, 75,2% e 91,6%. Atualmente, a endemia está presente nas áreas pantanosas, em lagos e nas regiões montanhosas. A manutenção do sucesso obtido e o controle efetivo nas áreas ainda endêmicas é um desafio que exigirá trabalho árduo e a longo prazo na República Popular da China.

  11. An accurate continuous calibration system for high voltage current transformer.

    Science.gov (United States)

    Tong, Yue; Li, Bin Hong

    2011-02-01

    A continuous calibration system for high voltage current transformers is presented in this paper. The sensor of this system is based on a kind of electronic instrument current transformer, which is a clamp-shape air core coil. This system uses an optical fiber transmission system for its signal transmission and power supply. Finally the digital integrator and fourth-order convolution window algorithm as error calculation methods are realized by the virtual instrument with a personal computer. It is found that this system can calibrate a high voltage current transformer while energized, which means avoiding a long calibrating period in the power system and the loss of power metering expense. At the same time, it has a wide dynamic range and frequency band, and it can achieve a high accuracy measurement in a complex electromagnetic field environment. The experimental results and the on-site operation results presented in the last part of the paper, prove that it can reach the 0.05 accuracy class and is easy to operate on site.

  12. Compilation of current high-energy physics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wohl, C.G.; Kelly, R.L.; Armstrong, F.E.

    1981-05-01

    This is the fourth edition of the compilation of current high energy physics experiments. It is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and nine participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), the Institute for Nuclear Study, Tokyo (INS), KEK, Serpukhov (SERP), and SLAC. The compilation includes summaries of all high energy physics experiments at the above laboratories that (1) were approved (and not subsequently withdrawn) before about April 1981, and (2) had not completed taking of data by 1 January 1977. Only approved experiments are included.

  13. Compilation of current high-energy-physics experiments

    Energy Technology Data Exchange (ETDEWEB)

    Wohl, C.G.; Kelly, R.L.; Armstrong, F.E.

    1980-04-01

    This is the third edition of a compilation of current high energy physics experiments. It is a collaborative effort of the Berkeley Particle Data Group, the SLAC library, and ten participating laboratories: Argonne (ANL), Brookhaven (BNL), CERN, DESY, Fermilab (FNAL), the Institute for Nuclear Study, Tokyo (INS), KEK, Rutherford (RHEL), Serpukhov (SERP), and SLAC. The compilation includes summaries of all high energy physics experiments at the above laboratories that (1) were approved (and not subsequently withdrawn) before about January 1980, and (2) had not completed taking of data by 1 January 1976.

  14. Glucose Homeostasis During Short-term and Prolonged Exposure to High Altitudes

    Science.gov (United States)

    Ader, Marilyn; Bergman, Richard N.

    2015-01-01

    Most of the literature related to high altitude medicine is devoted to the short-term effects of high-altitude exposure on human physiology. However, long-term effects of living at high altitudes may be more important in relation to human disease because more than 400 million people worldwide reside above 1500 m. Interestingly, individuals living at higher altitudes have a lower fasting glycemia and better glucose tolerance compared with those who live near sea level. There is also emerging evidence of the lower prevalence of both obesity and diabetes at higher altitudes. The mechanisms underlying improved glucose control at higher altitudes remain unclear. In this review, we present the most current evidence about glucose homeostasis in residents living above 1500 m and discuss possible mechanisms that could explain the lower fasting glycemia and lower prevalence of obesity and diabetes in this population. Understanding the mechanisms that regulate and maintain the lower fasting glycemia in individuals who live at higher altitudes could lead to new therapeutics for impaired glucose homeostasis. PMID:25675133

  15. High-energy Neutrino Emission from Short Gamma-Ray Bursts: Prospects for Coincident Detection with Gravitational Waves

    Energy Technology Data Exchange (ETDEWEB)

    Kimura, Shigeo S.; Murase, Kohta; Mészáros, Peter [Department of Physics, Pennsylvania State University, University Park, PA 16802 (United States); Kiuchi, Kenta [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto, Kyoto 606-8502 (Japan)

    2017-10-10

    We investigate current and future prospects for coincident detection of high-energy neutrinos and gravitational waves (GWs). Short gamma-ray bursts (SGRBs) are believed to originate from mergers of compact star binaries involving neutron stars. We estimate high-energy neutrino fluences from prompt emission, extended emission (EE), X-ray flares, and plateau emission, and we show that neutrino signals associated with the EE are the most promising. Assuming that the cosmic-ray loading factor is ∼10 and the Lorentz factor distribution is lognormal, we calculate the probability of neutrino detection from EE by current and future neutrino detectors, and we find that the quasi-simultaneous detection of high-energy neutrinos, gamma-rays, and GWs is possible with future instruments or even with current instruments for nearby SGRBs having EE. We also discuss stacking analyses that will also be useful with future experiments such as IceCube-Gen2.

  16. High-energy Neutrino Emission from Short Gamma-Ray Bursts: Prospects for Coincident Detection with Gravitational Waves

    Science.gov (United States)

    Kimura, Shigeo S.; Murase, Kohta; Mészáros, Peter; Kiuchi, Kenta

    2017-10-01

    We investigate current and future prospects for coincident detection of high-energy neutrinos and gravitational waves (GWs). Short gamma-ray bursts (SGRBs) are believed to originate from mergers of compact star binaries involving neutron stars. We estimate high-energy neutrino fluences from prompt emission, extended emission (EE), X-ray flares, and plateau emission, and we show that neutrino signals associated with the EE are the most promising. Assuming that the cosmic-ray loading factor is ˜10 and the Lorentz factor distribution is lognormal, we calculate the probability of neutrino detection from EE by current and future neutrino detectors, and we find that the quasi-simultaneous detection of high-energy neutrinos, gamma-rays, and GWs is possible with future instruments or even with current instruments for nearby SGRBs having EE. We also discuss stacking analyses that will also be useful with future experiments such as IceCube-Gen2.

  17. Double-layer rotor magnetic shield performance analysis in high temperature superconducting synchronous generators under short circuit fault conditions

    Science.gov (United States)

    Hekmati, Arsalan; Aliahmadi, Mehdi

    2016-12-01

    High temperature superconducting, HTS, synchronous machines benefit from a rotor magnetic shield in order to protect superconducting coils against asynchronous magnetic fields. This magnetic shield, however, suffers from exerted Lorentz forces generated in light of induced eddy currents during transient conditions, e.g. stator windings short-circuit fault. In addition, to the exerted electromagnetic forces, eddy current losses and the associated effects on the cryogenic system are the other consequences of shielding HTS coils. This study aims at investigating the Rotor Magnetic Shield, RMS, performance in HTS synchronous generators under stator winding short-circuit fault conditions. The induced eddy currents in different circumferential positions of the rotor magnetic shield along with associated Joule heating losses would be studied using 2-D time-stepping Finite Element Analysis, FEA. The investigation of Lorentz forces exerted on the magnetic shield during transient conditions has also been performed in this paper. The obtained results show that double line-to-ground fault is of the most importance among different types of short-circuit faults. It was revealed that when it comes to the design of the rotor magnetic shields, in addition to the eddy current distribution and the associated ohmic losses, two phase-to-ground fault should be taken into account since the produced electromagnetic forces in the time of fault conditions are more severe during double line-to-ground fault.

  18. 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

    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...... Medium Voltage microgrid using PSCAD and simulation results prove its effectiveness against various Single Phase to Ground faults. The proposed method solves some of the protection issues associated with a high penetration level of Distributed Generation, as it is less sensitive to the variable short...... 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...

  19. High risk of unprecedented UK rainfall in the current climate.

    Science.gov (United States)

    Thompson, Vikki; Dunstone, Nick J; Scaife, Adam A; Smith, Doug M; Slingo, Julia M; Brown, Simon; Belcher, Stephen E

    2017-07-24

    In winter 2013/14 a succession of storms hit the UK leading to record rainfall and flooding in many regions including south east England. In the Thames river valley there was widespread flooding, with clean-up costs of over £1 billion. There was no observational precedent for this level of rainfall. Here we present analysis of a large ensemble of high-resolution initialised climate simulations to show that this event could have been anticipated, and that in the current climate there remains a high chance of exceeding the observed record monthly rainfall totals in many regions of the UK. In south east England there is a 7% chance of exceeding the current rainfall record in at least one month in any given winter. Expanding our analysis to some other regions of England and Wales the risk increases to a 34% chance of breaking a regional record somewhere each winter.A succession of storms during the 2013-2014 winter led to record flooding in the UK. Here, the authors use high-resolution climate simulations to show that this event could have been anticipated and that there remains a high chance of exceeding observed record monthly rainfall totals in many parts of the UK.

  20. What happens in Josephson junctions at high critical current densities

    Science.gov (United States)

    Massarotti, D.; Stornaiuolo, D.; Lucignano, P.; Caruso, R.; Galletti, L.; Montemurro, D.; Jouault, B.; Campagnano, G.; Arani, H. F.; Longobardi, L.; Parlato, L.; Pepe, G. P.; Rotoli, G.; Tagliacozzo, A.; Lombardi, F.; Tafuri, F.

    2017-07-01

    The impressive advances in material science and nanotechnology are more and more promoting the use of exotic barriers and/or superconductors, thus paving the way to new families of Josephson junctions. Semiconducting, ferromagnetic, topological insulator and graphene barriers are leading to unconventional and anomalous aspects of the Josephson coupling, which might be useful to respond to some issues on key problems of solid state physics. However, the complexity of the layout and of the competing physical processes occurring in the junctions is posing novel questions on the interpretation of their phenomenology. We classify some significant behaviors of hybrid and unconventional junctions in terms of their first imprinting, i.e., current-voltage curves, and propose a phenomenological approach to describe some features of junctions characterized by relatively high critical current densities Jc. Accurate arguments on the distribution of switching currents will provide quantitative criteria to understand physical processes occurring in high-Jc junctions. These notions are universal and apply to all kinds of junctions.

  1. Visual short-term memory for high resolution associations is impaired in patients with medial temporal lobe damage.

    Science.gov (United States)

    Koen, Joshua D; Borders, Alyssa A; Petzold, Michael T; Yonelinas, Andrew P

    2017-02-01

    The medial temporal lobe (MTL) plays a critical role in episodic long-term memory, but whether the MTL is necessary for visual short-term memory is controversial. Some studies have indicated that MTL damage disrupts visual short-term memory performance whereas other studies have failed to find such evidence. To account for these mixed results, it has been proposed that the hippocampus is critical in supporting short-term memory for high resolution complex bindings, while the cortex is sufficient to support simple, low resolution bindings. This hypothesis was tested in the current study by assessing visual short-term memory in patients with damage to the MTL and controls for high resolution and low resolution object-location and object-color associations. In the location tests, participants encoded sets of two or four objects in different locations on the screen. After each set, participants performed a two-alternative forced-choice task in which they were required to discriminate the object in the target location from the object in a high or low resolution lure location (i.e., the object locations were very close or far away from the target location, respectively). Similarly, in the color tests, participants were presented with sets of two or four objects in a different color and, after each set, were required to discriminate the object in the target color from the object in a high or low resolution lure color (i.e., the lure color was very similar or very different, respectively, to the studied color). The patients were significantly impaired in visual short-term memory, but importantly, they were more impaired for high resolution object-location and object-color bindings. The results are consistent with the proposal that the hippocampus plays a critical role in forming and maintaining complex, high resolution bindings. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

  2. High current precision long pulse electron beam position monitor

    CERN Document Server

    Nelson, S D; Fessenden, T J; Holmes, C

    2000-01-01

    Precision high current long pulse electron beam position monitoring has typically experienced problems with high Q sensors, sensors damped to the point of lack of precision, or sensors that interact substantially with any beam halo thus obscuring the desired signal. As part of the effort to develop a multi-axis electron beam transport system using transverse electromagnetic stripline kicker technology, it is necessary to precisely determine the position and extent of long high energy beams for accurate beam position control (6 - 40 MeV, 1 - 4 kA, 2 μs beam pulse, sub millimeter beam position accuracy.) The kicker positioning system utilizes shot-to-shot adjustments for reduction of relatively slow (< 20 MHz) motion of the beam centroid. The electron beams passing through the diagnostic systems have the potential for large halo effects that tend to corrupt position measurements.

  3. Current status of high energy nucleon-meson transport code

    Energy Technology Data Exchange (ETDEWEB)

    Takada, Hiroshi; Sasa, Toshinobu [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    Current status of design code of accelerator (NMTC/JAERI code), outline of physical model and evaluation of accuracy of code were reported. To evaluate the nuclear performance of accelerator and strong spallation neutron origin, the nuclear reaction between high energy proton and target nuclide and behaviors of various produced particles are necessary. The nuclear design of spallation neutron system used a calculation code system connected the high energy nucleon{center_dot}meson transport code and the neutron{center_dot}photon transport code. NMTC/JAERI is described by the particle evaporation process under consideration of competition reaction of intranuclear cascade and fission process. Particle transport calculation was carried out for proton, neutron, {pi}- and {mu}-meson. To verify and improve accuracy of high energy nucleon-meson transport code, data of spallation and spallation neutron fragment by the integral experiment were collected. (S.Y.)

  4. High-Specificity Targeted Functional Profiling in Microbial Communities with ShortBRED.

    Directory of Open Access Journals (Sweden)

    James Kaminski

    2015-12-01

    Full Text Available Profiling microbial community function from metagenomic sequencing data remains a computationally challenging problem. Mapping millions of DNA reads from such samples to reference protein databases requires long run-times, and short read lengths can result in spurious hits to unrelated proteins (loss of specificity. We developed ShortBRED (Short, Better Representative Extract Dataset to address these challenges, facilitating fast, accurate functional profiling of metagenomic samples. ShortBRED consists of two components: (i a method that reduces reference proteins of interest to short, highly representative amino acid sequences ("markers" and (ii a search step that maps reads to these markers to quantify the relative abundance of their associated proteins. After evaluating ShortBRED on synthetic data, we applied it to profile antibiotic resistance protein families in the gut microbiomes of individuals from the United States, China, Malawi, and Venezuela. Our results support antibiotic resistance as a core function in the human gut microbiome, with tetracycline-resistant ribosomal protection proteins and Class A beta-lactamases being the most widely distributed resistance mechanisms worldwide. ShortBRED markers are applicable to other homology-based search tasks, which we demonstrate here by identifying phylogenetic signatures of antibiotic resistance across more than 3,000 microbial isolate genomes. ShortBRED can be applied to profile a wide variety of protein families of interest; the software, source code, and documentation are available for download at http://huttenhower.sph.harvard.edu/shortbred.

  5. High temperature superconducting current leads for micro-SMES application

    Energy Technology Data Exchange (ETDEWEB)

    Niemann, R.C.; Cha, Y.S.; Hull, J.R. [Argonne National Lab., IL (United States); Buckles, W.E.; Weber, B.R. [Suerconductivity, Inc., Madison, WI (United States); Daugherty, M.A. [Los Alamos National Lab., NM (United States)

    1993-09-01

    SMES is being applied on a microscale (1--10 Mj stored energy) to improve electrical power quality. A major portion of the SMES refrigeration load is for cooling the conventional (copper, vapor- cooled) current leads that transfer energy between the magnet and the power-conditioning equipment. The lead refrigeration load can be reduced significantly by the use of high-temperature superconductors (HTSs). A HTS current lead suitable for micro-SMES application has been designed. The lower stage of the lead employs HTSs. A transition between the lower stage and the conventional upper-stage lead is heat-intercepted by a cryocooler. Details of the design are presented. Construction and operating experiences are discussed.

  6. Survey of Digital Feedback Systems in High Current Storage Rings

    Energy Technology Data Exchange (ETDEWEB)

    Teytelman, Dmitry

    2003-06-06

    In the last decade demand for brightness in synchrotron light sources and luminosity in circular colliders led to construction of multiple high current storage rings. Many of these new machines require feedback systems to achieve design stored beam currents. In the same time frame the rapid advances in the technology of digital signal processing allowed the implementation of these complex feedback systems. In this paper I concentrate on three applications of feedback to storage rings: orbit control in light sources, coupled-bunch instability control, and low-level RF control. Each of these applications is challenging in areas of processing bandwidth, algorithm complexity, and control of time-varying beam and system dynamics. I will review existing implementations as well as comment on promising future directions.

  7. Transcranial direct current stimulation improves short-term memory in an animal model of attention-deficit/hyperactivity disorder.

    Science.gov (United States)

    Leffa, Douglas Teixeira; de Souza, Andressa; Scarabelot, Vanessa Leal; Medeiros, Liciane Fernandes; de Oliveira, Carla; Grevet, Eugenio Horacio; Caumo, Wolnei; de Souza, Diogo Onofre; Rohde, Luis Augusto Paim; Torres, Iraci L S

    2016-02-01

    Attention deficit hyperactivity disorder (ADHD) is characterized by impairing levels of hyperactivity, impulsivity and inattention. However, different meta-analyses have reported disruptions in short and long-term memory in ADHD patients. Previous studies indicate that mnemonic dysfunctions might be the result of deficits in attentional circuits, probably due to ineffective dopaminergic modulation of hippocampal synaptic plasticity. In this study we aimed to evaluate the potential therapeutic effects of a neuromodulatory technique, transcranial direct current stimulation (tDCS), in short-term memory (STM) deficits presented by the spontaneous hypertensive rats (SHR), the most widely used animal model of ADHD. Adult male SHR and Wistar Kyoto rats (WKY) were subjected to a constant electrical current of 0.5 mA intensity applied on the frontal cortex for 20 min/day during 8 days. STM was evaluated with an object recognition test conducted in an open field. Exploration time and locomotion were recorded, and brain regions were dissected to determine dopamine and BDNF levels. SHR spent less time exploring the new object when compared to WKY, and tDCS improved object recognition deficits in SHR without affecting WKY performance. Locomotor activity was higher in SHR and it was not affected by tDCS. After stimulation, dopamine levels were increased in the hippocampus and striatum of both strains, while BDNF levels were increased only in the striatum of WKY. These findings suggest that tDCS on the frontal cortex might be able to improve STM deficits present in SHR, which is potentially related to dopaminergic neurotransmission in the hippocampus and striatum of those animals. Copyright © 2016. Published by Elsevier B.V.

  8. Concurrent Validity and Feasibility of Short Tests Currently Used to Measure Early Childhood Development in Large Scale Studies.

    Directory of Open Access Journals (Sweden)

    Marta Rubio-Codina

    Full Text Available In low- and middle-income countries (LIMCs, measuring early childhood development (ECD with standard tests in large scale surveys and evaluations of interventions is difficult and expensive. Multi-dimensional screeners and single-domain tests ('short tests' are frequently used as alternatives. However, their validity in these circumstances is unknown. We examined the feasibility, reliability, and concurrent validity of three multi-dimensional screeners (Ages and Stages Questionnaires (ASQ-3, Denver Developmental Screening Test (Denver-II, Battelle Developmental Inventory screener (BDI-2 and two single-domain tests (MacArthur-Bates Short-Forms (SFI and SFII, WHO Motor Milestones (WHO-Motor in 1,311 children 6-42 months in Bogota, Colombia. The scores were compared with those on the Bayley Scales of Infant and Toddler Development (Bayley-III, taken as the 'gold standard'. The Bayley-III was given at a center by psychologists; whereas the short tests were administered in the home by interviewers, as in a survey setting. Findings indicated good internal validity of all short tests except the ASQ-3. The BDI-2 took long to administer and was expensive, while the single-domain tests were quickest and cheapest and the Denver-II and ASQ-3 were intermediate. Concurrent validity of the multi-dimensional tests' cognitive, language, and fine motor scales with the corresponding Bayley-III scale was low below 19 months. However, it increased with age, becoming moderate-to-high over 30 months. In contrast, gross motor scales' concurrence was high under 19 months and then decreased. Of the single-domain tests, the WHO-Motor had high validity with gross motor under 16 months, and the SFI and SFII expressive scales showed moderate correlations with language under 30 months. Overall, the Denver-II was the most feasible and valid multi-dimensional test and the ASQ-3 performed poorly under 31 months. By domain, gross motor development had the highest concurrence

  9. New progress of high current gasdynamic ion source (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Skalyga, V., E-mail: skalyga@ipfran.ru; Sidorov, A.; Vodopyanov, A. [Institute of Applied Physics, Russian Academy of Sciences (IAP RAS), 46 Ul‘yanova St., 603950 Nizhny Novgorod (Russian Federation); Lobachevsky State University of Nizhny Novgorod (UNN), 23 Gagarina St., 603950 Nizhny Novgorod (Russian Federation); Izotov, I.; Golubev, S.; Razin, S. [Institute of Applied Physics, Russian Academy of Sciences (IAP RAS), 46 Ul‘yanova St., 603950 Nizhny Novgorod (Russian Federation); Tarvainen, O.; Koivisto, H.; Kalvas, T. [Department of Physics, University of Jyvaskyla, P.O. Box 35 (YFL), 40500 Jyvaskyla (Finland)

    2016-02-15

    The experimental and theoretical research carried out at the Institute of Applied Physics resulted in development of a new type of electron cyclotron resonance ion sources (ECRISs)—the gasdynamic ECRIS. The gasdynamic ECRIS features a confinement mechanism in a magnetic trap that is different from Geller’s ECRIS confinement, i.e., the quasi-gasdynamic one similar to that in fusion mirror traps. Experimental studies of gasdynamic ECRIS were performed at Simple Mirror Ion Source (SMIS) 37 facility. The plasma was created by 37.5 and 75 GHz gyrotron radiation with power up to 100 kW. High frequency microwaves allowed to create and sustain plasma with significant density (up to 8 × 10{sup 13} cm{sup −3}) and to maintain the main advantages of conventional ECRIS such as high ionization degree and low ion energy. Reaching such high plasma density relies on the fact that the critical density grows with the microwave frequency squared. High microwave power provided the average electron energy on a level of 50-300 eV enough for efficient ionization even at neutral gas pressure range of 10{sup −4}–10{sup −3} mbar. Gasdynamic ECRIS has demonstrated a good performance producing high current (100-300 mA) multi-charged ion beams with moderate average charge (Z = 4-5 for argon). Gasdynamic ECRIS has appeared to be especially effective in low emittance hydrogen and deuterium beams formation. Proton beams with current up to 500 emA and RMS emittance below 0.07 π ⋅ mm ⋅ mrad have been demonstrated in recent experiments.

  10. Drinking high amounts of alcohol as a short-term mating strategy : the impact of short-term mating motivations on young adults’ drinking behavior

    OpenAIRE

    Eveline Vincke

    2017-01-01

    Previous research indicates that drinking large quantities of alcohol could function as a short-term mating strategy for young adults in mating situations. However, no study investigated whether this is actually the case. Therefore, in this article, the link between short-term mating motivations and drinking high amounts of alcohol is tested. First, a survey study (N = 345) confirmed that young adults who engage in binge drinking are more short-term oriented in their mating strategy than youn...

  11. 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

    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...... 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...

  12. Modeling of leakage currents in high-k dielectrics

    Energy Technology Data Exchange (ETDEWEB)

    Jegert, Gunther Christian

    2012-03-15

    Leakage currents are one of the major bottlenecks impeding the downscaling efforts of the semiconductor industry. Two core devices of integrated circuits, the transistor and, especially, the DRAM storage capacitor, suffer from the increasing loss currents. In this perspective a fundamental understanding of the physical origin of these leakage currents is highly desirable. However, the complexity of the involved transport phenomena so far has prevented the development of microscopic models. Instead, the analysis of transport through the ultra-thin layers of high-permittivity (high-k) dielectrics, which are employed as insulating layers, was carried out at an empirical level using simple compact models. Unfortunately, these offer only limited insight into the physics involved on the microscale. In this context the present work was initialized in order to establish a framework of microscopic physical models that allow a fundamental description of the transport processes relevant in high-k thin films. A simulation tool that makes use of kinetic Monte Carlo techniques was developed for this purpose embedding the above models in an environment that allows qualitative and quantitative analyses of the electronic transport in such films. Existing continuum approaches, which tend to conceal the important physics behind phenomenological fitting parameters, were replaced by three-dimensional transport simulations at the level of single charge carriers. Spatially localized phenomena, such as percolation of charge carriers across pointlike defects, being subject to structural relaxation processes, or electrode roughness effects, could be investigated in this simulation scheme. Stepwise a self-consistent, closed transport model for the TiN/ZrO{sub 2} material system, which is of outmost importance for the semiconductor industry, was developed. Based on this model viable strategies for the optimization of TiN/ZrO{sub 2}/TiN capacitor structures were suggested and problem areas

  13. High-current Standing Wave Linac With Gyrocon Power Source

    CERN Document Server

    Karliner, M M; Makarov, I G; Nezhevenko, O A; Ostreiko, G N; Persov, B Z; Serdobintsev, G V

    2004-01-01

    A gyrocon together with high-voltage 1.5 MeV accelerator ELIT-3A represents a power generator at 430 MHz serving for linear electron accelerator pulse driving. The facility description and results of calorimetric measurements of ELIT-3A electron beam power and accelerated beam at the end of accelerator are presented in the paper. 2.2 amps of pulsed current have been obtained at electron energy of 20 MeV. The achieved energy conversion efficiency is about 55%.

  14. Observed currents on the earth's high-latitude magnetopause

    Science.gov (United States)

    Van Allen, J. A.; Adnan, J.

    1992-01-01

    A survey of electrical currents of the earth's magnetosphere, principally at high latitudes, as inferred from magnetic vector data acquired by the Hawkeye 1 satellite, is reported. A total of 536 candidate crossings of the magnetopause were examined. A reduced data set of 139 selected cases was analyzed in detail though solar wind dynamic pressure data were available for only 117 of these cases. Inferred values of the lineal current densities on the magnetopause are in the range 5.5 to 157.5 mA/m over a wide range of solar wind dynamic pressure from 1.17 to 16.1 nPa. The apparent normal thickness of the magnetopause current sheet ranges from 30 to 850 km with mean and median values of 185 and 158 km, respectively. It is argued that the radial rate of motion of the magnetopause is of the order of 2 km/s and hence that its true thickness is of similar magnitude. The relationship of these results to models of the geomagnetic field and to other related work is discussed.

  15. Two high accuracy digital integrators for Rogowski current transducers

    Science.gov (United States)

    Luo, Pan-dian; Li, Hong-bin; Li, Zhen-hua

    2014-01-01

    The Rogowski current transducers have been widely used in AC current measurement, but their accuracy is mainly subject to the analog integrators, which have typical problems such as poor long-term stability and being susceptible to environmental conditions. The digital integrators can be another choice, but they cannot obtain a stable and accurate output for the reason that the DC component in original signal can be accumulated, which will lead to output DC drift. Unknown initial conditions can also result in integral output DC offset. This paper proposes two improved digital integrators used in Rogowski current transducers instead of traditional analog integrators for high measuring accuracy. A proportional-integral-derivative (PID) feedback controller and an attenuation coefficient have been applied in improving the Al-Alaoui integrator to change its DC response and get an ideal frequency response. For the special design in the field of digital signal processing, the improved digital integrators have better performance than analog integrators. Simulation models are built for the purpose of verification and comparison. The experiments prove that the designed integrators can achieve higher accuracy than analog integrators in steady-state response, transient-state response, and temperature changing condition.

  16. Early Stage of Pulsed High Current Discharge with Copper Powder

    Science.gov (United States)

    Yokoyama, Takuma; Kuraoka, Takuya; Takano, Kazuya; Ibuka, Shinji; Yasuoka, Koichi; Ishii, Shozo

    Early phase of powder plasmas powered by a pulsed high current discharge was examined by use of high-speed cameras and a laser shadowgraph and schlieren techniques. Initial electrons created by a pre-ionization discharge collide with both an anode and powder particles, of which surfaces evaporate after then. Evaporation of the particle by electron collision initially occured in the hemisphere surface which is close to cathode side. Since vaporization of the anode far exceeds that of the particles, discharge characteristics is almost similar to that of vacuum sparks in which expanding anode plasmas are observed. In order to suppress the developpment of the anode plasma, reduction of the effective anode area by varying the anode shape was examined.

  17. The Transition to High School: Current Knowledge, Future Directions

    Science.gov (United States)

    2011-01-01

    In the American educational system, school transitions are frequent and predictable, but they can disrupt student functioning across developmental domains. How students experience school transitions has been a focus of research for some time, but the high school transition has received less attention, and the limited research often focuses on a particular developmental domain (e.g., academics and socioemotional well-being) to the exclusion of a more integrated model. This review relies on life course theory to establish an organizational framework for interpreting and connecting the diffuse and sometimes disparate findings on the high school transition, including adolescent developmental trajectories and the influence of social ties, changing sociocultural contexts, and stratification systems. Conclusions identify aspects for future inquiry suggested by current knowledge and the tenets of the life course perspective. PMID:21966178

  18. High resolution modelling of the North Icelandic Irminger Current (NIIC

    Directory of Open Access Journals (Sweden)

    K. Logemann

    2006-01-01

    Full Text Available The northward inflow of Atlantic Water through Denmark Strait – the North Icelandic Irminger Current (NIIC – is simulated with a numerical model of the North Atlantic and Arctic Ocean. The model uses the technique of adaptive grid refinement which allows a high spatial resolution (1 km horizontal, 10 m vertical around Iceland. The model is used to assess time and space variability of volume and heat fluxes for the years 1997–2003. Passive tracers are applied to study origin and composition of NIIC water masses. The NIIC originates from two sources: the Irminger Current, flowing as part of the sub-polar gyre in 100–500 m depth along the Reykjanes Ridge and the shallow Icelandic coastal current, flowing north-westward on the south-west Icelandic shelf. The ratio of volume flux between the deep and shallow branch is around 2:1. The NIIC continues as a warm and saline branch northward through Denmark Strait where it entrains large amounts of polar water due to the collision with the southward flowing East Greenland Current. After passing Denmark Strait, the NIIC follows the coast line eastward being an important heat source for north Icelandic waters. At least 60% of the temporal temperature variability of north Icelandic waters is caused by the NIIC. The NIIC volume and heat transport is highly variable and depends strongly on the wind field north-east of Denmark Strait. Daily means can change from 1 Sv eastward to 2 Sv westward within a few days. Highest monthly mean transport rates occur in summer when winds from north are weak, whereas the volume flux is reduced by around 50% in winter. Summer heat flux rates can be even three times higher than in winter. The simulation also shows variability on the interannual scale. In particular weak winds from north during winter 2002/2003 combined with mild weather conditions south of Iceland led to anomalous high NIIC volume (+40% and heat flux (+60% rates. In this period, simulated north Icelandic

  19. Short aramid-fiber reinforced ultra-high molecular weight polyethylene

    NARCIS (Netherlands)

    Hofste, JM; Bergmans, KJR; deBoer, J; Wevers, R; Pennings, AJ

    Ultra-High Molecular Weight Polyethylene (UHMWPE) is frequently used in artificial joints because of its high wear resistance. To extend the lifetime of these joints even further, it is necessary to decrease the wear rate. The wear rate may be decreased by blending UHMWPE with short aramid fibers.

  20. Isotopic germanium targets for high beam current applications at GAMMASPHERE.

    Energy Technology Data Exchange (ETDEWEB)

    Greene, J. P.; Lauritsen, T.

    2000-11-29

    The creation of a specific heavy ion residue via heavy ion fusion can usually be achieved through a number of beam and target combinations. Sometimes it is necessary to choose combinations with rare beams and/or difficult targets in order to achieve the physics goals of an experiment. A case in point was a recent experiment to produce {sup 152}Dy at very high spins and low excitation energy with detection of the residue in a recoil mass analyzer. Both to create the nucleus cold and with a small recoil-cone so that the efficiency of the mass analyzer would be high, it was necessary to use the {sup 80}Se on {sup 76}Ge reaction rather than the standard {sup 48}Ca on {sup 108}Pd reaction. Because the recoil velocity of the {sup 152}Dy residues was very high using this symmetric reaction (5% v/c), it was furthermore necessary to use a stack of two thin targets to reduce the Doppler broadening. Germanium targets are fragile and do not withstand high beam currents, therefore the {sup 76}Ge target stacks were mounted on a rotating target wheel. A description of the {sup 76}Ge target stack preparation will be presented and the target performance described.

  1. Comparison of Short and Continuous Hydration Regimen in Chemotherapy Containing Intermediate- to High-Dose Cisplatin

    Directory of Open Access Journals (Sweden)

    Akira Ouchi

    2014-01-01

    Full Text Available Aim. The efficacy of the short hydration regimen was reported in chemotherapy containing intermediate- to high-dose cisplatin, and the use of outpatient chemotherapy containing cisplatin with short hydration has been widespread in recent years. Methods. We compared patients with gastric cancer, lung cancer, and urothelial cancer who received outpatient chemotherapy containing cisplatin (≥60 mg/m2/cycle with the short hydration regimen since April 2012 (n=13 with those who received hospital chemotherapy with continuous hydration between April 2011 and March 2013 (n=17 in our hospital. Results. Grade 2 or higher acute kidney injury occurred in 2 patients in the continuous hydration group and in no patient in the short hydration group; 1 patient discontinued treatment on account of nephrotoxicity. There was no difference between the 2 groups in maximum creatinine increment and maximum clearance decrement. Relative dose intensity in the short hydration group was higher than that in the continuous hydration group (89.5% versus 80.3%; P<0.01. Conclusions. The short hydration regimen in outpatient chemotherapy containing intermediate- to high-dose cisplatin is as safe as the continuous hydration regimen and increased the efficacy of chemotherapy.

  2. Novel short-pulse laser diode source for high-resolution 3D flash lidar

    Science.gov (United States)

    Canal, Celine; Laugustin, Arnaud; Kohl, Andreas; Rabot, Olivier

    2017-06-01

    Imaging based on laser illumination is present in various fields of applications such as medicine, security, defense, civil engineering and in the automotive sector. In this last domain, research and development to bring autonomous vehicles on the roads has been intensified the recent years. Among the various technologies currently studied, automotive lidars are a fast-growing one due to their accuracy to detect a wide range of objects at distances up to a few hundreds of meters in various weather conditions. First commercialized devices for ADAS were laser scanners. Since then, new architectures have recently appeared such as solid-state lidar and flash lidar that offer a higher compactness, robustness and a cost reduction. Flash lidars are based on time-of-flight measurements, with the particularity that they do not require beam scanners because only one short laser pulse with a large divergence is used to enlighten the whole scene. Depth of encountered objects can then be recovered from measurement of echoed light at once, hence enabling real-time 3D mapping of the environment. This paper will bring into the picture a cutting edge laser diode source that can deliver millijoule pulses as short as 12 ns, which makes them highly suitable for integration in flash lidars. They provide a 100-kW peak power highly divergent beam in a footprint of 4x5 cm2 (including both the laser diode and driver) and with a 30-% electrical-to-optical efficiency, making them suitable for integration in environments in which compactness and power consumption are a priority. Their emission in the range of 800-1000 nm is considered to be eye safe when taking into account the high divergence of the output beam. An overview of architecture of these state-of-the-art pulsed laser diode sources will be given together with some solutions for their integration in 3D mapping systems. Future work leads will be discussed for miniaturization of the laser diode and drastic cost reduction.

  3. Current status and future of high energy physics

    Energy Technology Data Exchange (ETDEWEB)

    Tu, T.

    1977-03-01

    With respect to the present knowledge of the internal structure of matter, nothing is known about the structure of leptons or photons, and just a little about the structure of hadrons. Some of the most important questions to be answered in high-energy physics are the following: how many kinds of quarks are there and how can they be isolated; how are quarks bound to form hadrons; can weak, electromagnetic, and strong interactions all be described by a single unified theory; are there new types of leptons; and are there new phenomena not conceived of yet. New particles may be discovered by large accelerators scheduled for completion in West Germany, the United States, and the Soviet Union about 1980. The factors vital to China's long-range development of high-energy physics are personnel well-versed in Marxism--Leninism and Mao Tse-tung's thought, particle accelerators with high energies, strong currents, and many kinds of particle beams, and an advanced particle detection and data processing technology.

  4. Improved Turn-on Characteristics of Fast High Current Thyristors

    CERN Document Server

    Ducimetière, L; Vossenberg, Eugène B

    1999-01-01

    The beam dumping system of CERN's Large Hadron Collider (LHC) is equipped with fast solid state closing switches, designed for a hold-off voltage of 30 kV and a quasi half sine wave current of 20 kA, with 3 ms rise time, a maximum di/dt of 12 kA/ms and 2 ms fall time. The design repetition rate is 20 s. The switch is composed of ten Fast High Current Thyristors (FHCT’s), which are modified symmetric 4.5 kV GTO thyristors of WESTCODE. Recent studies aiming at improving the turn-on delay, switching speed and at decreasing the switch losses, have led to test an asymmetric not fully optimised GTO thyristor of WESTCODE and an optimised device of GEC PLESSEY Semiconductor (GPS), GB. The GPS FHCT, which gave the best results, is a non irradiated device of 64 mm diameter with a hold-off voltage of 4.5 kV like the symmetric FHCT. Tests results of the GPS FHCT show a reduction in turn-on delay of 40 % and in switching losses of almost 50 % with respect to the symmetric FHCT of WESTCODE. The GPS device can sustain an i...

  5. Minimum component high frequency current mode rectifier | Sampe ...

    African Journals Online (AJOL)

    In this paper a current mode full wave rectifier circuit is proposed. The current mode rectifier circuit is implemented utilizing a floating current source (FCS) as an active element. The minimum component full wave rectifier utilizes only a single floating current source, two diodes and two grounded resistors. The extremely ...

  6. Ultra-high current density thin-film Si diode

    Science.gov (United States)

    Wang, Qi [Littleton, CO

    2008-04-22

    A combination of a thin-film .mu.c-Si and a-Si:H containing diode structure characterized by an ultra-high current density that exceeds 1000 A/cm.sup.2, comprising: a substrate; a bottom metal layer disposed on the substrate; an n-layer of .mu.c-Si deposited the bottom metal layer; an i-layer of .mu.c-Si deposited on the n-layer; a buffer layer of a-Si:H deposited on the i-layer, a p-layer of .mu.c-Si deposited on the buffer layer; and a top metal layer deposited on the p-layer.

  7. PENETRATION AND DEFECT FORMATION IN HIGH CURRENT ARC WELDING

    Energy Technology Data Exchange (ETDEWEB)

    MENDEZ,P.F.; EAGAR, T.W.

    2003-01-01

    The work performed during the three previous years can be roughly divided into two main categories: (1) development of advanced modeling techniques; and (2) modeling of arc welding process. The work in the first category comprised the development of the Order of Magnitude Scaling (OMS) technique, which is complementary to numerical modeling techniques such as finite elements, but it provides approximate formulas instead of just numerical results. Borrowing concepts from OMS, another modeling technique based on empirical data was also developed. During this stage special software was also developed. The second category comprised the application of OMS to the three main subsystems of arc welding: the weld pool, the arc, and the electrode. For each of these subsystems they found scaling laws and regimes. With this knowledge, they analyzed the generation of weld pool defects during high current arc welding, proposed a mechanistic description of the process, and possible solutions.

  8. Gravity Currents with Convective Mixing: High-resolution Numerical Simulations

    Science.gov (United States)

    Voskov, D.; Elenius, M. T.; Tchelepi, H.

    2014-12-01

    Due to challenges in performing direct numerical simulations for gravity currents with convective mixing, different attempts have been made to simplify the problem. In this work, the full problem is investigated with direct numerical simulations. Our simulations employ a recently developed capability in our General Purpose Research Simulator (AD-GPRS). The compositional approach is based on K-values and a linear density model. A shared-memory parallel implementation allows for high resolution simulations in a reasonable time frame. Our results indicate that it is important to consider the reduction in the dissolution rate after the fingers begin to interact with the bottom of the aquifer. Another important observation suggests considering a reduction in the dissolution rate where the plume thickness increases in time. In addition to the large-scale simulations, we performed convective-mixing simulations in relatively small domains to support the analysis of large-scale plume migration and CO2 trapping.

  9. Short-time, high-dosage penicillin infusion therapy of syphilis

    DEFF Research Database (Denmark)

    Lomholt, Hans; Poulsen, Asmus; Brandrup, Flemming

    2003-01-01

    The optimal dosage and duration of penicillin treatment for the various stages of syphilis are not known. We present data on 20 patients with syphilis (primary, secondary or latent) treated with high-dose, short-time penicillin infusion therapy. Patients were given 10 MIU of penicillin G intraven......The optimal dosage and duration of penicillin treatment for the various stages of syphilis are not known. We present data on 20 patients with syphilis (primary, secondary or latent) treated with high-dose, short-time penicillin infusion therapy. Patients were given 10 MIU of penicillin G...

  10. An ultra-high discrimination Y chromosome short tandem repeat multiplex DNA typing system.

    Directory of Open Access Journals (Sweden)

    Erin K Hanson

    Full Text Available In forensic casework, Y chromosome short tandem repeat markers (Y-STRs are often used to identify a male donor DNA profile in the presence of excess quantities of female DNA, such as is found in many sexual assault investigations. Commercially available Y-STR multiplexes incorporating 12-17 loci are currently used in forensic casework (Promega's PowerPlex Y and Applied Biosystems' AmpFlSTR Yfiler. Despite the robustness of these commercial multiplex Y-STR systems and the ability to discriminate two male individuals in most cases, the coincidence match probabilities between unrelated males are modest compared with the standard set of autosomal STR markers. Hence there is still a need to develop new multiplex systems to supplement these for those cases where additional discriminatory power is desired or where there is a coincidental Y-STR match between potential male participants. Over 400 Y-STR loci have been identified on the Y chromosome. While these have the potential to increase the discrimination potential afforded by the commercially available kits, many have not been well characterized. In the present work, 91 loci were tested for their relative ability to increase the discrimination potential of the commonly used 'core' Y-STR loci. The result of this extensive evaluation was the development of an ultra high discrimination (UHD multiplex DNA typing system that allows for the robust co-amplification of 14 non-core Y-STR loci. Population studies with a mixed African American and American Caucasian sample set (n = 572 indicated that the overall discriminatory potential of the UHD multiplex was superior to all commercial kits tested. The combined use of the UHD multiplex and the Applied Biosystems' AmpFlSTR Yfiler kit resulted in 100% discrimination of all individuals within the sample set, which presages its potential to maximally augment currently available forensic casework markers. It could also find applications in human evolutionary

  11. The high current transport experiment for heavy ion inertial fusion

    Energy Technology Data Exchange (ETDEWEB)

    Prost, L.R.; Baca, D.; Bieniosek, F.M.; Celata, C.M.; Faltens, A.; Henestroza, E.; Kwan, J.W.; Leitner, M.; Seidl, P.A.; Waldron, W.L.; Cohen, R.; Friedman, A.; Grote, D.; Lund, S.M.; Molvik, A.W.; Morse, E.

    2004-05-01

    The High Current Experiment (HCX) at Lawrence Berkeley National Laboratory is part of the US program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density {approx} 0.2 {micro}C/m) over long pulse durations (4 {micro}s) in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo and, electron and gas cloud effects. We present the results for a coasting 1 MeV K{sup +} ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius) for which the transverse phase-space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor ({approx}80%) is achieved with acceptable emittance growth and beam loss, even though the initial beam distribution is not ideal (but the emittance is low) nor in thermal equilibrium. We achieved good envelope control, and rematching may only be needed every ten lattice periods (at 80% fill factor) in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.

  12. High current transport experiment for heavy ion inertial fusion

    Directory of Open Access Journals (Sweden)

    L. R. Prost

    2005-02-01

    Full Text Available The High Current Experiment at Lawrence Berkeley National Laboratory is part of the U.S. program to explore heavy-ion beam transport at a scale representative of the low-energy end of an induction linac driver for fusion energy production. The primary mission of this experiment is to investigate aperture fill factors acceptable for the transport of space-charge-dominated heavy-ion beams at high intensity (line charge density ∼0.2  μC/m over long pulse durations (4  μs in alternating gradient focusing lattices of electrostatic or magnetic quadrupoles. This experiment is testing transport issues resulting from nonlinear space-charge effects and collective modes, beam centroid alignment and steering, envelope matching, image charges and focusing field nonlinearities, halo, and electron and gas cloud effects. We present the results for a coasting 1 MeV K^{+} ion beam transported through ten electrostatic quadrupoles. The measurements cover two different fill factor studies (60% and 80% of the clear aperture radius for which the transverse phase space of the beam was characterized in detail, along with beam energy measurements and the first halo measurements. Electrostatic quadrupole transport at high beam fill factor (≈80% is achieved with acceptable emittance growth and beam loss, even though the initial beam distribution is not ideal (but the emittance is low nor in thermal equilibrium. We achieved good envelope control, and rematching may only be needed every ten lattice periods (at 80% fill factor in a longer lattice of similar design. We also show that understanding and controlling the time dependence of the envelope parameters is critical to achieving high fill factors, notably because of the injector and matching section dynamics.

  13. Drinking High Amounts of Alcohol as a Short-Term Mating Strategy: The Impact of Short-Term Mating Motivations on Young Adults' Drinking Behavior.

    Science.gov (United States)

    Vincke, Eveline

    2017-01-01

    Previous research indicates that drinking large quantities of alcohol could function as a short-term mating strategy for young adults in mating situations. However, no study investigated whether this is actually the case. Therefore, in this article, the link between short-term mating motivations and drinking high amounts of alcohol is tested. First, a survey study ( N = 345) confirmed that young adults who engage in binge drinking are more short-term oriented in their mating strategy than young adults who never engage in binge drinking. Also, the more short-term-oriented young adults were in their mating strategy, the more often binge drinking behavior was conducted. In addition, an experimental study ( N = 229) empirically verified that short-term mating motivations increase young adults' drinking behavior, more so than long-term mating motivations. Results of the experiment clearly showed that young men and young women are triggered to drink more alcoholic beverages in a short-term mating situation compared to a long-term mating situation. Furthermore, the mating situation also affected young adults' perception of drinking behavior. Young adults in a short-term mating context perceived a higher amount of alcoholic beverages as heavy drinking compared to peers in a long-term mating context. These findings confirm that a high alcohol consumption functions as a short-term mating strategy for both young men and young women. Insights gained from this article might be of interest to institutions aimed at targeting youth alcohol (ab)use.

  14. Drinking High Amounts of Alcohol as a Short-Term Mating Strategy: The Impact of Short-Term Mating Motivations on Young Adults’ Drinking Behavior

    Directory of Open Access Journals (Sweden)

    Eveline Vincke

    2017-05-01

    Full Text Available Previous research indicates that drinking large quantities of alcohol could function as a short-term mating strategy for young adults in mating situations. However, no study investigated whether this is actually the case. Therefore, in this article, the link between short-term mating motivations and drinking high amounts of alcohol is tested. First, a survey study (N = 345 confirmed that young adults who engage in binge drinking are more short-term oriented in their mating strategy than young adults who never engage in binge drinking. Also, the more short-term-oriented young adults were in their mating strategy, the more often binge drinking behavior was conducted. In addition, an experimental study (N = 229 empirically verified that short-term mating motivations increase young adults’ drinking behavior, more so than long-term mating motivations. Results of the experiment clearly showed that young men and young women are triggered to drink more alcoholic beverages in a short-term mating situation compared to a long-term mating situation. Furthermore, the mating situation also affected young adults’ perception of drinking behavior. Young adults in a short-term mating context perceived a higher amount of alcoholic beverages as heavy drinking compared to peers in a long-term mating context. These findings confirm that a high alcohol consumption functions as a short-term mating strategy for both young men and young women. Insights gained from this article might be of interest to institutions aimed at targeting youth alcohol (abuse.

  15. [Short gel method for pretreatment of protein samples with high concentration of detergent].

    Science.gov (United States)

    Ma, Shouzhi; Zhang, Tao; Zhai, Linhui; Sun, Yulin; Xu, Ping; Zhao, Xiaohang

    2014-09-01

    In proteomic research, to improve protein solubility of membrane proteins and nuclear proteins, buffers containing high concentration of detergent, such as 4% SDS, were widely used. However, high concentration of detergent might severely interfere with the downstream proteomic analysis, including protein quantitation and trypsin digestion. To improve the proteomic compatibility of buffers with high concentration of detergent, we used short gel method to pretreat buffers containing detergent. Protein samples were first separated by a short (2-2.5 mm) SDS-PAGE electrophoresis, and proteins were quantitated by comparing with bovine serum albumin standards via optical density analysis. The gel was then cut and peptides were recovered using in-gel digestion. The quantitative linearity range of this method was 1 to 8 μg. The quantitation was accurate and reproducible. After short gel analysis, recovered peptides generated high mass spectrometry signals. In conclusion, short gel method eliminated the interference of high concentration detergent in the proteomics analysis, and it was suitable for protein samples' pretreatment, and was worth to apply in proteomic research.

  16. Effect of dislocations on the open-circuit voltage, short-circuit current and efficiency of heteroepitaxial indium phosphide solar cells

    Science.gov (United States)

    Jain, Raj K.; Flood, Dennis J.

    1990-01-01

    Excellent radiation resistance of indium phosphide solar cells makes them a promising candidate for space power applications, but the present high cost of starting substrates may inhibit their large scale use. Thin film indium phosphide cells grown on Si or GaAs substrates have exhibited low efficiencies, because of the generation and propagation of large number of dislocations. Dislocation densities were calculated and its influence on the open circuit voltage, short circuit current, and efficiency of heteroepitaxial indium phosphide cells was studied using the PC-1D. Dislocations act as predominant recombination centers and are required to be controlled by proper transition layers and improved growth techniques. It is shown that heteroepitaxial grown cells could achieve efficiencies in excess of 18 percent AMO by controlling the number of dislocations. The effect of emitter thickness and surface recombination velocity on the cell performance parameters vs. dislocation density is also studied.

  17. A short review of our current understanding of the development of ring faults during collapse caldera formation

    Directory of Open Access Journals (Sweden)

    Adelina eGeyer

    2014-09-01

    Full Text Available The term collapse caldera refers to those volcanic depressions resulting from the sinking of the chamber roof due to the rapid withdrawal of magma during the course of an eruption. During the last three decades, collapse caldera dynamics has been the focus of attention of numerous, theoretical, numerical and experimental studies. Nonetheless, even if there is a tendency to go for a general and comprehensive caldera dynamics model, some key aspects remain unclear, controversial or completely unsolved. This is the case of ring fault nucleation points and propagation and dip direction. Since direct information on calderas’ deeper structure comes mainly from partially eroded calderas or few witnessed collapses, ring faults layout at depth remains still uncertain. This has generated a strong debate over the detailed internal fault and fracture configuration of a caldera collapse and, in more detail, how ring faults initiate and propagate. We offer here a very short description of the main results obtained by those analogue and theoretical/mathematical models applied to the study of collapse caldera formation. We place special attention on those observations related to the nucleation and propagation of the collapse-controlling ring faults. This summary is relevant to understand the current state-of-the-art of this topic and it should be taken under consideration in future works dealing with collapse caldera dynamics.

  18. Current-day precision oncology: from cancer prevention, screening, drug development, and treatment - have we fallen short of the promise?

    Science.gov (United States)

    Morgan, Gilberto; Aftimos, Philippe; Awada, Ahmad

    2016-09-01

    Precision oncology has been a strategy of prevention, screening, and treatment. Although much has been invested, have the results fallen so far short of the promise? The advancement of technology and research has opened new doors, yet a variety of pitfalls are present. This review presents the successes, failures, and opportunities of precision oncology in the current landscape. The use of targeted gene sequencing and the overwhelming results of superresponders have generated much excitement and support for precision oncology from the medical community. Despite notable successes, many challenges still pave the way of precision oncology: intratumoral heterogeneity, the need for serial biopsies, availability of treatments, target prioritization, ethical issues with germline incidental findings, medical education, clinical trial design, and costs. Precision oncology shows much potential through the use of next-generation sequencing and molecular advances, but does this potential warrant the investment? There are many obstacles on the way of this technology that should make us question if the investment (both monetary and man-hours) will live up to the promise. The review aims to not criticize this technology, but to give a realistic view of where we are, especially regarding cancer treatment and prevention.

  19. A short review of our current understanding of the development of ring faults during collapse caldera formation

    Science.gov (United States)

    Geyer, Adelina; Marti, Joan

    2014-09-01

    The term collapse caldera refers to those volcanic depressions resulting from the sinking of the chamber roof due to the rapid withdrawal of magma during the course of an eruption. During the last three decades, collapse caldera dynamics has been the focus of attention of numerous, theoretical, numerical and experimental studies. Nonetheless, even if there is a tendency to go for a general and comprehensive caldera dynamics model, some key aspects remain unclear, controversial or completely unsolved. This is the case of ring fault nucleation points and propagation and dip direction. Since direct information on calderas’ deeper structure comes mainly from partially eroded calderas or few witnessed collapses, ring faults layout at depth remains still uncertain. This has generated a strong debate over the detailed internal fault and fracture configuration of a caldera collapse and, in more detail, how ring faults initiate and propagate. We offer here a very short description of the main results obtained by those analogue and theoretical/mathematical models applied to the study of collapse caldera formation. We place special attention on those observations related to the nucleation and propagation of the collapse-controlling ring faults. This summary is relevant to understand the current state-of-the-art of this topic and it should be taken under consideration in future works dealing with collapse caldera dynamics.

  20. Radial direct bandgap p-i-n GaNP microwire solar cells with enhanced short circuit current

    Energy Technology Data Exchange (ETDEWEB)

    Sukrittanon, Supanee [Graduate Program of Materials Science and Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Liu, Ren; Pan, Janet L. [Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Breeden, Michael C. [Department of Nanoengineering, University of California, San Diego, La Jolla, California 92037 (United States); Jungjohann, K. L. [Center for Integrated Nanotechnologies, Sandia National Laboratories, Albuquerque, New Mexico 87185 (United States); Tu, Charles W., E-mail: ctu@ece.ucsd.edu, E-mail: sdayeh@ece.ucsd.edu; Dayeh, Shadi A., E-mail: ctu@ece.ucsd.edu, E-mail: sdayeh@ece.ucsd.edu [Graduate Program of Materials Science and Engineering, University of California, San Diego, La Jolla, California 92037 (United States); Department of Electrical and Computer Engineering, University of California, San Diego, La Jolla, California 92037 (United States)

    2016-08-07

    We report the demonstration of dilute nitride heterostructure core/shell microwire solar cells utilizing the combination of top-down reactive-ion etching to create the cores (GaP) and molecular beam epitaxy to create the shells (GaNP). Systematic studies of cell performance over a series of microwire lengths, array periods, and microwire sidewall morphologies examined by transmission electron microscopy were conducted to shed light on performance-limiting factors and to optimize the cell efficiency. We show by microscopy and correlated external quantum efficiency characterization that the open circuit voltage is degraded primarily due to the presence of defects at the GaP/GaNP interface and in the GaNP shells, and is not limited by surface recombination. Compared to thin film solar cells in the same growth run, the microwire solar cells exhibit greater short circuit current but poorer open circuit voltage due to greater light absorption and number of defects in the microwire structure, respectively. The comprehensive understanding presented in this work suggests that performance benefits of dilute nitride microwire solar cells can be achieved by further tuning of the epitaxial quality of the underlying materials.

  1. Clipper for High-Impedance Current-Drive Line

    Science.gov (United States)

    Woodhouse, Christopher E.

    1987-01-01

    New circuit leakage reduced by shunting current through saturated input at operational-amplifier follower already part of Howland, or equivalent, current source. Typical application is in circuit of germanium resistance thermometer in cryogenic system.

  2. Forecasting the Short-Term Passenger Flow on High-Speed Railway with Neural Networks

    Directory of Open Access Journals (Sweden)

    Mei-Quan Xie

    2014-01-01

    Full Text Available Short-term passenger flow forecasting is an important component of transportation systems. The forecasting result can be applied to support transportation system operation and management such as operation planning and revenue management. In this paper, a divide-and-conquer method based on neural network and origin-destination (OD matrix estimation is developed to forecast the short-term passenger flow in high-speed railway system. There are three steps in the forecasting method. Firstly, the numbers of passengers who arrive at each station or depart from each station are obtained from historical passenger flow data, which are OD matrices in this paper. Secondly, short-term passenger flow forecasting of the numbers of passengers who arrive at each station or depart from each station based on neural network is realized. At last, the OD matrices in short-term time are obtained with an OD matrix estimation method. The experimental results indicate that the proposed divide-and-conquer method performs well in forecasting the short-term passenger flow on high-speed railway.

  3. Development of a high average current polarized electron source with long cathode operational lifetime

    Directory of Open Access Journals (Sweden)

    C. K. Sinclair

    2007-02-01

    Full Text Available Substantially more than half of the electromagnetic nuclear physics experiments conducted at the Continuous Electron Beam Accelerator Facility of the Thomas Jefferson National Accelerator Facility (Jefferson Laboratory require highly polarized electron beams, often at high average current. Spin-polarized electrons are produced by photoemission from various GaAs-based semiconductor photocathodes, using circularly polarized laser light with photon energy slightly larger than the semiconductor band gap. The photocathodes are prepared by activation of the clean semiconductor surface to negative electron affinity using cesium and oxidation. Historically, in many laboratories worldwide, these photocathodes have had short operational lifetimes at high average current, and have often deteriorated fairly quickly in ultrahigh vacuum even without electron beam delivery. At Jefferson Lab, we have developed a polarized electron source in which the photocathodes degrade exceptionally slowly without electron emission, and in which ion back bombardment is the predominant mechanism limiting the operational lifetime of the cathodes during electron emission. We have reproducibly obtained cathode 1/e dark lifetimes over two years, and 1/e charge density and charge lifetimes during electron beam delivery of over 2×10^{5}   C/cm^{2} and 200 C, respectively. This source is able to support uninterrupted high average current polarized beam delivery to three experimental halls simultaneously for many months at a time. Many of the techniques we report here are directly applicable to the development of GaAs photoemission electron guns to deliver high average current, high brightness unpolarized beams.

  4. Validation of the Short Form of the Career Development Inventory with an Iranian High School Sample

    Science.gov (United States)

    Sadeghi, Ahmad; Baghban, Iran; Bahrami, Fatemeh; Ahmadi, Ahmad; Creed, Peter

    2011-01-01

    A short 33-item form of the Career Development Inventory was validated on a sample of 310 Iranian high school students. Factor analysis indicated that attitude and cognitive subscale items loaded on their respective factors, and that internal reliability coefficients at all levels were satisfactory to good. Support for validity was demonstrated by…

  5. A short-term high fat diet increases exposure to midazolam and omeprazole in healthy subjects

    NARCIS (Netherlands)

    Achterbergh, Roos; Lammers, Laureen A.; van Nierop, Samuel; Klümpen, Heinz-Josef; Soeters, Maarten R.; Mathôt, Ron A. A.; Romijn, Johannes A.

    2016-01-01

    Knowledge of factors contributing to variation in drug metabolism is of vital importance to optimize drug treatment. This study assesses the effects of a short-term hypercaloric high fat diet on metabolism of five oral drugs, which are each specific for a single P450 isoform: midazolam (CYP3A4),

  6. R & D on Very-High-Current Superconducting Proton Linac, Final Report

    Energy Technology Data Exchange (ETDEWEB)

    Ben-Zvi, Ilan [Stony Brook Univ., NY (United States)

    2013-03-31

    The aim of this R&D project was to develop a superconducting cavity for a very-­ high-current proton accelerator. The particular application motivating the proposal was a LHC upgrade called the Superconducting Proton Linac, or SPL. Under the grant awarded to Stony Brook University the cavity was designed, a prototype copper cavity, followed by the niobium cavity, were built. A new set of HOM dampers was developed. The cavity has outstanding RF performance parameters – low surface fields, low power loss and all HOMs are fully damped. In fact, it is a “universal cavity” in the sense that it is suited for the acceleration of high-­current protons and well as high current electrons. Its damping of HOM modes is so good that it can see service in a multi-pass linac or an Energy Recovery Linac in addition to the easier service in a single-pass linac. Extensive measurements were made on the cavities and couplers, with the exception of the cold test of the niobium cavity. At the time of this report the cavity has been chemically processed and is ready for vertical testing which will be carried out shortly.

  7. Review of high-power pulsed systems at the Institute of High Current Electronics

    Directory of Open Access Journals (Sweden)

    A.A. Kim

    2016-07-01

    Full Text Available In this paper, we give a review of some most powerful pulsed systems developed at the Institute of High Current Electronics (HCEI, Siberian Branch, Russian Academy of Sciences, and describe latest achievements of the teams dealing with these installations. Besides the presented high-power systems, HCEI performs numerous investigations using much less powerful generators. For instance, last year much attention was paying to the research and development of the intense low-energy (<200 kV high-current electron and ion beam and plasma sources, and their application in the technology [1–3].

  8. High efficiency off-axis current drive by high frequency fast waves

    Science.gov (United States)

    Prater, R.; Pinsker, R. I.; Moeller, C. P.; Porkolab, M.; Vdovin, V.

    2014-02-01

    Modeling work shows that current drive can be done off-axis with high efficiency, as required for FNSF and DEMO, by using very high harmonic fast waves ("helicons" or "whistlers"). The modeling indicates that plasmas with high electron beta are needed in order for the current drive to take place off-axis, making DIII-D a highly suitable test vehicle for this process. The calculations show that the driven current is not very sensitive to the launched value of n∥, a result that can be understood from examination of the evolution of n∥ as the waves propagate in the plasma. Because of this insensitivity, relatively large values (˜3) of n∥ can be launched, thereby avoiding some of the problems with mode conversion in the boundary found in some previous experiments. Use of a traveling wave antenna provides a very narrow n∥ spectrum, which also helps avoid mode conversion.

  9. Demonstration of short-range wind lidar in a high-performance wind tunnel

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Montes, Belen Fernández; Pedersen, Jens Engholm

    A short-range continuous-wave coherent laser radar (lidar) has been tested in a high-performance wind tunnel for possible use as a standard component in wind tunnels. The lidar was tested in a low as well as a high speed regime ranging from 5-35 m/s and 40-75 m/s, respectively. In both low and high......-speed regimes very good correlation with reference measurements was found. Furthermore different staring directions were tested and taking a simple geometrical correction into account very good correlation was again found. These measurements all demonstrate the high accuracy of the lidar and indicate a possible...... future for short range lidars as a complement to LDA and other standard equipment in wind tunnels....

  10. Demonstration of short-range wind lidar in a high-performance wind tunnel

    DEFF Research Database (Denmark)

    Pedersen, Anders Tegtmeier; Montes, Belen Fernández; Pedersen, Jens Engholm

    2012-01-01

    A short-range continuous-wave coherent laser radar (lidar) has been tested in a high-performance wind tunnel for possible use as a standard component in wind tunnels. The lidar was tested in a low as well as a high speed regime ranging from 5-35 m/s and 40-75 m/s, respectively. In both low and high......-speed regimes very good correlation with reference measurements was found. Furthermore different staring directions were tested and taking a simple geometrical correction into account very good correlation was again found. These measurements all demonstrate the high accuracy of the lidar and indicate a possible...... future for short range lidars as a complement to LDA and other standard equipment in wind tunnels....

  11. High-density matter: current status and future challenges

    Directory of Open Access Journals (Sweden)

    Stone J. R.

    2015-01-01

    Full Text Available There are many fascinating processes in the Universe which we observe in more and more in detail thanks to increasingly sophisticated technology. One of the most interesting phenomena is the life cycle of stars, their birth, evolution and death. If the stars are massive enough, they end their lives in the core-collapse supernova explosion, the one of the most violent events in the Universe. As the result, the densest objects in the Universe, neutron stars and/or black holes are created. Naturally, the physical basis of these events should be understood in line with observation. The current status of our knowledge of processes in the life of stars is far from adequate for their true understanding. We show that although many models have been constructed their detailed ability to describe observations is limited or non-existent. Furthermore the general failure of all models means that we cannot tell which are heading in the right direction. A possible way forward in modeling of high-density matter is outlined, exemplified by the quark-meson-coupling model (QMC. This model has a natural explanation for the saturation of nuclear forces and depends on very few adjustable parameters, strongly constrained by the underlying physics. Latest QMC results for compact objects and finite nuclei are presented.

  12. Space charge templates for high-current beam modeling

    Energy Technology Data Exchange (ETDEWEB)

    Vorobiev, Leonid G.; /Fermilab

    2008-07-01

    A computational method to evaluate space charge potential and gradients of charged particle beam in the presence of conducting boundaries, has been introduced. The three-dimensional (3D) field of the beam can be derived as a convolution of macro Green's functions (template fields), satisfying the same boundary conditions, as the original beam. Numerical experiments gave a confidence that space charge effects can be modeled by templates with enough accuracy and generality within dramatically faster computational times than standard combination: a grid density + Poisson solvers, realized in the most of Particle in Cell codes. The achieved rapidity may significantly broaden the high-current beam design space, making the optimization in automatic mode possible, which so far was only feasible for simplest self-field formulations such as rms envelope equations. The template technique may be used as a standalone program, or as an optional field solver in existing beam dynamics codes both in one-passage structures and in rings.

  13. A Short review on wrought austenitic stainless steels at high temperatures: processing, microstructure, properties and performance

    Directory of Open Access Journals (Sweden)

    Ronald Lesley Plaut

    2007-12-01

    Full Text Available Wrought austenitic stainless steels are widely used in high temperature applications. This short review discusses initially the processing of this class of steels, with emphasis on solidification and hot working behavior. Following, a brief summary is made on the precipitation behavior and the numerous phases that may appear in their microstructures. Creep and oxidation resistance are, then, briefly discussed, and finalizing their performance is compared with other high temperature metallic materials.

  14. A PICTORIAL PRESENTATION OF ESOPHAGEAL HIGH RESOLUTION MANOMETRY CURRENT PARAMETERS.

    Science.gov (United States)

    Lafraia, Fernanda M; Herbella, Fernando A M; Kalluf, Julia R; Patti, Marco G

    2017-01-01

    High resolution manometry is the current technology used to the study of esophageal motility and is replacing conventional manometry in important centers for esophageal motility with parameters used on esophageal motility, following the Chicago Classification. This classification unifies high resolution manometry interpretation and classifies esophageal disorders. This review shows, in a pictorial presentation, the new parameters established by the Chicago Classification, version 3.0, aimed to allow an easy comprehension and interpretation of high resolution manometry. Esophageal manometries performed by the authors were reviewed to select illustrative tracings representing Chicago Classification parameters. The parameters are: Esophagogastric Morphology, that classifies this junction according to its physiology and anatomy; Integrated Relaxation Pressure, that measures the lower esophageal sphincter relaxation; Distal Contractile Integral, that evaluates the contraction vigor of each wave; and, Distal Latency, that measures the peristalsis velocity from the beginning of the swallow to the epiphrenic ampulla. Clinical applications of these new concepts is still under evaluation. Mostrar, de forma pictórica, os novos parâmetros compilados na versão 3.0 da Classificação de Chicago, buscando facilitar a compreensão e interpretação da manometria de alta resolução. Foram revistas as manometrias da casuística dos autores e selecionados os traçados representativos dos parâmetros da Classificação de Chicago. Entre os parâmetros apresentados foram considerados a Morfologia da Transição Gastroesofágica, que classifica o segmento de acordo com sua fisiologia e anatomia; a Integral da Pressão de Relaxamento, que mede o relaxamento do esfíncter esofagiano inferior; a Integral Contrátil Distal, que avalia o vigor contrátil da onda peristáltica; e, a Latência Distal, que mede o tempo da peristalse, desde o início da deglutição até a ampola epifr

  15. High Current, Multi-Filament Photoconductive Semiconductor Switching

    Science.gov (United States)

    2011-06-01

    excellent approach, if the lasing uniformity could be maintained to assure current - sharing Vertical cavity surface emitting lasers ( VCSELs ) Figure 9...development of VCSELS with sufficient intensity and uniformity to trigger current -sharing, linear filaments has been slow. To date, two parallel filaments...have been triggered with VCSELS emitting dashed lines to improve their uniformity [18 The simplest approach to triggering current -sharing, linear

  16. High-Temperature-Short-Time Annealing Process for High-Performance Large-Area Perovskite Solar Cells.

    Science.gov (United States)

    Kim, Minjin; Kim, Gi-Hwan; Oh, Kyoung Suk; Jo, Yimhyun; Yoon, Hyun; Kim, Ka-Hyun; Lee, Heon; Kim, Jin Young; Kim, Dong Suk

    2017-06-27

    Organic-inorganic hybrid metal halide perovskite solar cells (PSCs) are attracting tremendous research interest due to their high solar-to-electric power conversion efficiency with a high possibility of cost-effective fabrication and certified power conversion efficiency now exceeding 22%. Although many effective methods for their application have been developed over the past decade, their practical transition to large-size devices has been restricted by difficulties in achieving high performance. Here we report on the development of a simple and cost-effective production method with high-temperature and short-time annealing processing to obtain uniform, smooth, and large-size grain domains of perovskite films over large areas. With high-temperature short-time annealing at 400 °C for 4 s, the perovskite film with an average domain size of 1 μm was obtained, which resulted in fast solvent evaporation. Solar cells fabricated using this processing technique had a maximum power conversion efficiency exceeding 20% over a 0.1 cm2 active area and 18% over a 1 cm2 active area. We believe our approach will enable the realization of highly efficient large-area PCSs for practical development with a very simple and short-time procedure. This simple method should lead the field toward the fabrication of uniform large-scale perovskite films, which are necessary for the production of high-efficiency solar cells that may also be applicable to several other material systems for more widespread practical deployment.

  17. Microstructure Evolution of Cu-Cored Sn Solder Joints Under High Temperature and High Current Density

    Science.gov (United States)

    Sa, Xianzhang; Wu, Ping

    2013-08-01

    This work investigated the microstructure evolution of Cu-cored Sn solder joints under high temperature and high current density. The Cu6Sn5 phase formed at both the Cu core/Sn interface and Cu wire/Sn interface right after reflow and grew with increasing annealing time, while the Cu3Sn phase formed and grew at the Cu/Cu6Sn5 interfaces. Intermetallic compound (IMC) growth followed a linear relationship with the square root of annealing time due to a diffusion-controlled mechanism. Under high current density, the thickness of the interfacial IMCs of the Cu core/Sn interface at the cathode side increased and the Cu core/Sn interface at the anode side exhibited an irregular and serrated morphology with prolonged current stressing time. Finite-element simulation was carried out to obtain the distribution of current density in the solder joint. Since Cu has lower resistivity, the electrical current primarily selected the Cu core as its electrical path, resulting in current crowding at the Cu core and the region between the Cu core and Cu wire. Compared with the conventional solder joint, the electromigration (EM) lifetime of the Cu-cored solder joint was much longer.

  18. Optimization of the short-circuit current in an InP nanowire array solar cell through opto-electronic modeling

    Science.gov (United States)

    Chen, Yang; Kivisaari, Pyry; Pistol, Mats-Erik; Anttu, Nicklas

    2016-10-01

    InP nanowire arrays with axial p-i-n junctions are promising devices for next-generation photovoltaics, with a demonstrated efficiency of 13.8%. However, the short-circuit current in such arrays does not match their absorption performance. Here, through combined optical and electrical modeling, we study how the absorption of photons and separation of the resulting photogenerated electron-hole pairs define and limit the short-circuit current in the nanowires. We identify how photogenerated minority carriers in the top n segment (i.e. holes) diffuse to the ohmic top contact where they recombine without contributing to the short-circuit current. In our modeling, such contact recombination can lead to a 60% drop in the short-circuit current. To hinder such hole diffusion, we include a gradient doping profile in the n segment to create a front surface barrier. This approach leads to a modest 5% increase in the short-circuit current, limited by Auger recombination with increased doping. A more efficient approach is to switch the n segment to a material with a higher band gap, like GaP. Then, a much smaller number of holes is photogenerated in the n segment, strongly limiting the amount that can diffuse and disappear into the top contact. For a 500 nm long top segment, the GaP approach leads to a 50% higher short-circuit current than with an InP top segment. Such a long top segment could facilitate the fabrication and contacting of nanowire array solar cells. Such design schemes for managing minority carriers could open the door to higher performance in single- and multi-junction nanowire-based solar cells.

  19. High Tension Electric Current Injury and Silent Myocardial Infarction ...

    African Journals Online (AJOL)

    A 55-year-old male, non-diabetic, sustained severe electric current injury as evidenced by the grievous exit wound on the left dorsum of foot as well as entry wound in both palms. There was silent anterior wall myocardial infarction, discovered from incidental electrocardiograph. Keywords: Electric current injury, grievous exit ...

  20. Multiple-Stage Converter Topology for High-Precision High-Current Pulsed Sources

    CERN Document Server

    Wassinger, N; Benedetti, M; Carrica, D; Retegui, R G; Cravero, J M

    2011-01-01

    A new high-current, low-rise-time, and high-precision pulse generator is presented. The topology is based on the use of different stages, each one specific for a particular operation range in terms of power and switching frequency. This approach allows to accomplish current, voltage, and precision requirements with standard semiconductors. Moreover, the proposed topology provides an independent and flexible adjustment of the pulse parameters (rise and fall times, flat-top duration, pulse amplitude, etc.). Experimental results are provided to validate the control of the proposed topology.

  1. Impact of short-term high-fat feeding on glucose and insulin metabolism in young healthy men

    DEFF Research Database (Denmark)

    Brøns, Charlotte; Jensen, Christine B.; Storgaard, Heidi

    2009-01-01

    A high-fat, high-calorie diet is associated with obesity and type 2 diabetes. However, the relative contribution of metabolic defects to the development of hyperglycaemia and type 2 diabetes is controversial. Accumulation of excess fat in muscle and adipose tissue in insulin resistance and type 2...... diabetes may be linked with defective mitochondrial oxidative phosphorylation. The aim of the current study was to investigate acute effects of short-term fat overfeeding on glucose and insulin metabolism in young men. We studied the effects of 5 days' high-fat (60% energy) overfeeding (+50%) versus...... a control diet on hepatic and peripheral insulin action by a hyperinsulinaemic euglycaemic clamp, muscle mitochondrial function by (31)P magnetic resonance spectroscopy, and gene expression by qrt-PCR and microarray in 26 young men. Hepatic glucose production and fasting glucose levels increased...

  2. A DEMO relevant fast wave current drive high harmonic antenna exploiting the high impedance technique

    Energy Technology Data Exchange (ETDEWEB)

    Milanesio, D., E-mail: daniele.milanesio@polito.it; Maggiora, R. [Politecnico di Torino, Dipartimento di Elettronica e Telecomunicazioni (DET), Torino (Italy)

    2015-12-10

    Ion Cyclotron (IC) antennas are routinely adopted in most of the existing nuclear fusion experiments, even though their main goal, i.e. to couple high power to the plasma (MW), is often limited by rather severe drawbacks due to high fields on the antenna itself and on the unmatched part of the feeding lines. In addition to the well exploited auxiliary ion heating during the start-up phase, some non-ohmic current drive (CD) at the IC range of frequencies may be explored in view of the DEMO reactor. In this work, we suggest and describe a compact high frequency DEMO relevant antenna, based on the high impedance surfaces concept. High-impedance surfaces are periodic metallic structures (patches) usually displaced on top of a dielectric substrate and grounded by means of vertical posts embedded inside the dielectric, in a mushroom-like shape. These structures present a high impedance, within a given frequency band, such that the image currents are in-phase with the currents of the antenna itself, thus determining a significant efficiency increase. After a general introduction on the properties of high impedance surfaces, we analyze, by means of numerical codes, a dielectric based and a full metal solution optimized to be tested and benchmarked on the FTU experiment fed with generators at 433MHz.

  3. Adaptive slope compensation for high bandwidth digital current mode controller

    DEFF Research Database (Denmark)

    Taeed, Fazel; Nymand, Morten

    2015-01-01

    An adaptive slope compensation method for digital current mode control of dc-dc converters is proposed in this paper. The compensation slope is used for stabilizing the inner current loop in peak current mode control. In this method, the compensation slope is adapted with the variations...... in converter duty cycle. The adaptive slope compensation provides optimum controller operation in term of bandwidth over wide range of operating points. In this paper operation principle of the controller is discussed. The proposed controller is implemented in an FPGA to control a 100 W buck converter...

  4. The development of InGaAs short wavelength infrared focal plane arrays with high performance

    Science.gov (United States)

    Li, Xue; Gong, Haimei; Fang, Jiaxiong; shao, Xiumei; Tang, Hengjing; Huang, Songlei; Li, Tao; Huang, Zhangcheng

    2017-01-01

    High performance, various specifications InGaAs focal plane arrays(FPAs) were studied in Shanghai Institute of Technical Physics (SITP). On the one hand, the typical linear 256 × 1, 512 × 1 and 1024 × 1 FPAs were obtained for response wavelengths from 0.9 μm to 1.7 μm. The typical 320 × 256 FPAs and special sizes 512 × 128, 512 × 256 FPAs for the near infrared multi-spectral imaging were studied. The performance of InGaAs FPAs from 0.9 μm to 1.7 μm has improved enormously. The average peak detectivity, the response non-uniformity and non-operable pixel of the FPAs are superior to 3 × 1012 cm Hz1/2/W, 5% and 1% at the room temperature. On the other hand, the development of the extended InGaAs FPAs was also focused in SITP. The dark current of InGaAs detectors with the response wavelength from 1.0 μm to 2.5 μm decreases to about 10 nA/cm2 at 200 K. The dark current mechanisms for extended InGaAs detectors were studied by P/A photodiodes. The special sizes 512 × 256 FPAs has been fabricated since 2011. The average peak detectivity, the response non-uniformity and non-operable pixel of the FPAs are superior to 5 × 1011 cm Hz1/2/W, 8% and 2% at 200 K. In order to verify the performance of FPAs, the short wavelength infrared lens was used to form optical imaging system. The buildings, water, trees are sharply imaged by 320 × 256 FPAs with 0.9-1.7 μm wavelength and 512 × 1 FPAs with 0.9-2.5 μm wavelength at about hundreds of meters distance as target at daylight.

  5. A miniature high voltage plasma interaction flight experiment - Project MINX. [for measuring solar cell array parasitic current drain

    Science.gov (United States)

    Riley, T. J.; Triner, J. E.; Sater, B. L.; Cohen, D.; Somberg, H.

    1974-01-01

    A miniature high-voltage array was fabricated, incorporating the multi-junction edge illuminated (MJC) cell technique. The array consists of 32 2x2.2 cm MJCs, series connected, capable of 1600 V open circuit at 1 AMO and 1.2 mA short circuit. A solid state, high-voltage relay is connected across each 4-cell subgroup of the array. It was built to test plasma current drain on space systems using high voltage as might occur when a high-voltage solar array is operated from low to synchronous orbit.

  6. The impact of sunlight on high-latitude equivalent currents

    CERN Document Server

    Laundal, K M; Østgaard, N; Reistad, J P; Haaland, S; Snekvik, K; Tenfjord, P; Ohtani, S; Milan, S E

    2016-01-01

    Ground magnetic field measurements can be mathematically related to an overhead ionospheric equivalent current. In this study we look in detail at how the global equivalent current, calculated using more than 30 years of SuperMAG magnetometer data, changes with sunlight conditions. The calculations are done using spherical harmonic analysis in quasi-dipole coordinates, a technique which leads to improved accuracy compared to previous studies. Sorting the data according to the location of the sunlight terminator and orientation of the interplanetary magnetic field (IMF), we find that the equivalent current resembles ionospheric convection patterns on the sunlit side of the terminator but not on the dark side. On the dark side, with southward IMF, the current is strongly dominated by a dawn cell and the current across the polar cap has a strong dawnward component. The contrast between the sunlit and dark side increases with increasing values of the $\\mathit{F}_{10.7}$ index, showing that increasing solar EUV fl...

  7. Analysis of Electric Vehicle DC High Current Conversion Technology

    Science.gov (United States)

    Yang, Jing; Bai, Jing-fen; Lin, Fan-tao; Lu, Da

    2017-05-01

    Based on the background of electric vehicles, it is elaborated the necessity about electric energy accurate metering of electric vehicle power batteries, and it is analyzed about the charging and discharging characteristics of power batteries. It is needed a DC large current converter to realize accurate calibration of power batteries electric energy metering. Several kinds of measuring methods are analyzed based on shunts and magnetic induction principle in detail. It is put forward power batteries charge and discharge calibration system principle, and it is simulated and analyzed ripple waves containing rate and harmonic waves containing rate of power batteries AC side and DC side. It is put forward suitable DC large current measurement methods of power batteries by comparing different measurement principles and it is looked forward the DC large current measurement techniques.

  8. High Speed High Resolution Current Comparator and its Application to Analog to Digital Converter

    Science.gov (United States)

    Sridhar, Ranjana; Pandey, Neeta; Bhattacharyya, Asok; Bhatia, Veepsa

    2016-06-01

    This paper introduces a high speed high resolution current comparator which includes the current differencing stage and employs non linear feedback in the gain stage. The usefulness of the proposed comparator is demonstrated by implementing a 3-bit current mode flash analog-to-digital converter (ADC). Simulation program with integrated circuit emphasis (SPICE) simulations have been carried out to verify theoretical proposition and performance parameters of both comparator and ADC are obtained using TSMC 0.18 µm CMOS technology parameters. The current comparator shows a resolution of ±5 nA and a delay of 0.86 ns for current difference of ±1 µA. The impact of process variation on proposed comparator propagation delay has been studied through Monte Carlo simulation and it is found that percentage change in propagation delay in best case is 1.3 % only and in worst case is 9 % only. The ADC exhibits an offset, gain error, differential nonlinearity (DNL) and integral nonlinearity (INL) of 0.102 µA, 0.99, -0.34 LSB and 0.0267 LSB, respectively. The impact of process variation on ADC has also been studied at different process corners.

  9. High Current Planar Transformer for Very High Efficiency Isolated Boost DC-DC Converters

    DEFF Research Database (Denmark)

    Pittini, Riccardo; Zhang, Zhe; Andersen, Michael A. E.

    2014-01-01

    This paper presents a design and optimization of a high current planar transformer for very high efficiency dc-dc isolated boost converters. The analysis considers different winding arrangements, including very high copper thickness windings. The analysis is focused on the winding ac......-resistance and transformer leakage inductance. Design and optimization procedures are validated based on an experimental prototype of a 6 kW dcdc isolated full bridge boost converter developed on fully planar magnetics. The prototype is rated at 30-80 V 0-80 A on the low voltage side and 700-800 V on the high voltage side...... with a peak efficiency of 97.8% at 80 V 3.5 kW. Results highlights that thick copper windings can provide good performance at low switching frequencies due to the high transformer filling factor. PCB windings can also provide very high efficiency if stacked in parallel utilizing the transformer winding window...

  10. Stator winding short-circuit fault detection in a permanent magnet synchronous motor (PMSM using negative sequence current in time domain

    Directory of Open Access Journals (Sweden)

    Jabid E. Quiroga

    2009-05-01

    Full Text Available A negative sequence analysis in time domain was applied to fault detection of permanent magnet synchronous motors (PMSM. The fundamental components of the motor terminal currents were obtained using a Notch filter, based on which the negative se- quence components in time domain were then calculated; the negative sequence current constituted the stator winding short-cir- cuit fault indicator. The negative sequence current also provided a qualitative evaluation regarding the severity of the fault. The proposed method promptly (< 22 ms and reliably determined the stator winding short for different levels of severity in faults around and greater than 6.25% of the shorted phase. Experimental studies confirmed the proportional relationship between fault indicator and the level of severity. Using negative sequence current in time domain reduced computational cost and detection ti- me compared to that in frequency domain. The proposed method could be extended to detect the shorted phase to improve mo- nitoring. The method was validated online using a PMSM experimental setup with dSPACE and Matlab/Simulink environment.

  11. High current DC negative ion source for cyclotron.

    Science.gov (United States)

    Etoh, H; Onai, M; Aoki, Y; Mitsubori, H; Arakawa, Y; Sakuraba, J; Kato, T; Mitsumoto, T; Hiasa, T; Yajima, S; Shibata, T; Hatayama, A; Okumura, Y

    2016-02-01

    A filament driven multi-cusp negative ion source has been developed for proton cyclotrons in medical applications. In Cs-free operation, continuous H(-) beam of 10 mA and D(-) beam of 3.3 mA were obtained stably at an arc-discharge power of 3 kW and 2.4 kW, respectively. In Cs-seeded operation, H(-) beam current reached 22 mA at a lower arc power of 2.6 kW with less co-extracted electron current. The optimum gas flow rate, which gives the highest H(-) current, was 15 sccm in the Cs-free operation, while it decreased to 4 sccm in the Cs-seeded operation. The relationship between H(-) production and the design/operating parameters has been also investigated by a numerical study with KEIO-MARC code, which gives a reasonable explanation to the experimental results of the H(-) current dependence on the arc power.

  12. Short period, high field cryogenic undulator for extreme performance x-ray free electron lasers

    Directory of Open Access Journals (Sweden)

    F. H. O’Shea

    2010-07-01

    Full Text Available Short period, high field undulators can enable short wavelength free electron lasers (FELs at low beam energy, with decreased gain length, thus allowing much more compact and less costly FEL systems. We describe an ongoing initiative to develop such an undulator based on an approach that utilizes novel cryogenic materials. While this effort was begun in the context of extending the photon energy regime of a laser-plasma accelerator based electron source, we consider here implications of its application to sub-fs scenarios in which more conventional injectors are employed. The use of such low-charge, ultrashort beams, which has recently been proposed as a method of obtaining single-spike performance in x-ray FELs, is seen in simulation to give unprecedented beam brightness. This brightness, when considered in tandem with short wavelength, high field undulators, enables extremely high performance FELs. Two examples discussed in this paper illustrate this point well. The first is the use of the SPARX injector at 2.1 GeV with 1 pC of charge to give 8 GW peak power in a single spike at 6.5 Å with a photon beam peak brightness greater than 10^{35}  photons/(s mm^{2} mrad^{2}  0.1%  BW, which will also reach LCLS wavelengths on the 5th harmonic. The second is the exploitation of the LCLS injector with 0.25 pC, 150 as pulses to lase at 1.5 Å using only 4.5 GeV energy; beyond this possibility, we present start-to-end simulations of lasing at unprecedented short wavelength, 0.15 Å, using 13.65 GeV LCLS design energy.

  13. Brahan Project High Frequency Radar Ocean Measurements: Currents, Winds, Waves and Their Interactions

    OpenAIRE

    Belinda Lipa; Donald Barrick; Andres Alonso-Martirena; Maria Fernandes; Maria Inmaculada Ferrer; Bruce Nyden

    2014-01-01

    We describe radar measurements of waves, currents and winds made on the coast of northern Scotland during two 2013/14 winter storms, giving methods, results and interpretation. Wave parameters (height, period, direction and short-wave/wind direction) were derived and compared with measurements made by a neighboring buoy and local weather stations. Wind direction and current velocity maps were produced and the interactions of winds and currents discussed. Significant oscillations in wave param...

  14. OTDM Networking for Short Range High-Capacity Highly Dynamic Networks

    DEFF Research Database (Denmark)

    Medhin, Ashenafi Kiros

    This PhD thesis aims at investigating the possibility of designing energy-efficient high-capacity (up to Tbit/s) optical network scenarios, leveraging on the effect of collective switching of many bits simultaneously, as is inherent in high bit rate serial optical data signals. The focus...... Tbit/s data packets, and time lens based serial-to-parallel converter is employed to demultiplex each high-capacity packet into lower bit rate tributaries. A novel optical label scheme is suggested and experimentally demonstrated, where the label information is inserted in-band in the broad signal...... from 640 Gbit/s variable length data packets. Finally, three optical switching scenarios of high-capacity data packets, including a record-high 1×2 optical packet switching of 1.28 Tbit/s serial packets, are experimentally demonstrated using electro-optic based LiNbO3 switches....

  15. Progress on High-Speed 980 nm VCSELs for Short-Reach Optical Interconnects

    Directory of Open Access Journals (Sweden)

    Alex Mutig

    2011-01-01

    Full Text Available Progress of high-speed vertical cavity surface emitting lasers (VCSEL operating around 980 nm is reviewed. A special focus is on their applications for future short-reach optical interconnects, for example, in high-performance computers (HPC. The wavelength of 980 nm has fundamental advantages for these applications and plays a significant role in VCSEL research today. The present data rates of 980 nm VCSELs exceed 40 Gbit/s, and excellent temperature stability has been reported. The major concepts leading to these impressive developments are presented.

  16. High efficiency off-axis current drive by high frequency fast waves

    Energy Technology Data Exchange (ETDEWEB)

    Prater, R.; Pinsker, R. I.; Moeller, C. P. [General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States); Porkolab, M.; Vdovin, V. [Massachusetts Institute of Technology, 77 Massachusetts Ave., Cambridge, Massachusetts 02139 (United States)

    2014-02-12

    Modeling work shows that current drive can be done off-axis with high efficiency, as required for FNSF and DEMO, by using very high harmonic fast waves (“helicons” or “whistlers”). The modeling indicates that plasmas with high electron beta are needed in order for the current drive to take place off-axis, making DIII-D a highly suitable test vehicle for this process. The calculations show that the driven current is not very sensitive to the launched value of n{sub ∥}, a result that can be understood from examination of the evolution of n{sub ∥} as the waves propagate in the plasma. Because of this insensitivity, relatively large values (∼3) of n{sub ∥} can be launched, thereby avoiding some of the problems with mode conversion in the boundary found in some previous experiments. Use of a traveling wave antenna provides a very narrow n{sub ∥} spectrum, which also helps avoid mode conversion.

  17. The Effects of Music on High-intensity Short-term Exercise in Well Trained Athletes

    Science.gov (United States)

    Jarraya, Mohamed; Chtourou, Hamdi; Aloui, Asma; Hammouda, Omar; Chamari, Karim; Chaouachi, Anis; Souissi, Nizar

    2012-01-01

    Purpose The purpose of this investigation was to assess the effects of listening to music during warm-up on short-term supramaximal performances during the 30-s Wingate test in highly trained athletes. Methods Twelve young male athletes (20.6±1.8 yrs, 177±4.4 cm and 72.3±5.3 kg) underwent two Wingate tests in separate sessions with a recovery period of 48 h in-between, either after a 10 min of warm-up with (MWU) or without (NMWU) music. High tempo music (>120 to 140bpm) was selected for the study. Heart rate (HR) and rate of perceived exertion (RPE) were recorded after the warm-up (for HR = average of warm-up) and immediately after the Wingate test. Results HR, RPE and the fatigue index during the Wingate test are not affected by the incorporation of music during warm-up. However, power output (Ppeak and Pmean) was significantly higher after MWU than NMWU (Pmusic during warm-up on short-term supramaximal performances. Conclusions As it's a legal method and an additional aid, music may be used during warm-up before performing activities requiring powerful lower limbs’ muscles contractions during short-term supramaximal exercises. PMID:23342221

  18. Does Short-Term Hunger Increase Trust and Trustworthiness in a High Trust Society?

    Science.gov (United States)

    Rantapuska, Elias; Freese, Riitta; Jääskeläinen, Iiro P; Hytönen, Kaisa

    2017-01-01

    We build on the social heuristics hypothesis, the literature on the glucose model of self-control, and recent challenges on these hypotheses to investigate whether individuals exhibit a change in degree of trust and reciprocation after consumption of a meal. We induce short-term manipulation of hunger followed by the trust game and a decision on whether to leave personal belongings in an unlocked and unsupervised room. Our results are inconclusive. While, we report hungry individuals trusting and reciprocating more than those who have just consumed a meal in a high trust society, we fail to reject the null with small number of observations (N = 101) and experimental sessions (N = 8). In addition, we find no evidence of short-term hunger having an impact on charitable giving or decisions in public good game.

  19. A short-term high fat diet increases exposure to midazolam and omeprazole in healthy subjects.

    Science.gov (United States)

    Achterbergh, Roos; Lammers, Laureen A; van Nierop, Samuel; Klümpen, Heinz-Josef; Soeters, Maarten R; Mathôt, Ron A A; Romijn, Johannes A

    2016-07-01

    Knowledge of factors contributing to variation in drug metabolism is of vital importance to optimize drug treatment. This study assesses the effects of a short-term hypercaloric high fat diet on metabolism of five oral drugs, which are each specific for a single P450 isoform: midazolam (CYP3A4), omeprazole (CYP2C19), metoprolol (CYP2D6), S-warfarin (CYP2C9) and caffeine (CYP1A2). In 9 healthy volunteers, pharmacokinetics of the five drugs were assessed after an overnight fast at two separate occasions: after a regular diet and after 3 days of a hypercaloric high fat diet (i.e. regular diet supplemented with 500 mL cream [1715 kcal, 35% fat]). Pharmacokinetic parameters (mean [SEM]) were estimated by non-compartmental analysis. The high fat diet increased exposure to midazolam by 19% from 24.7 (2.6) to 29.5 (3.6) ng ml-1h-1 (p=0.04) and exposure to omeprazole by 31% from 726 (104) to 951 (168) ng ml-1h-1 (p=0.05). Exposure to metoprolol, caffeine and S-warfarin was not affected by the high fat diet. A short-term hypercaloric high fat diet increases exposure to midazolam and omeprazole, possibly reflecting modulation of CYP3A4 and CYP2C19.

  20. Neonatal overfeeding attenuates acute central pro-inflammatory effects of short-term high fat diet

    Directory of Open Access Journals (Sweden)

    Guohui eCai

    2015-01-01

    Full Text Available Neonatal obesity predisposes individuals to obesity throughout life. In rats, neonatal overfeeding also leads to early accelerated weight gain that persists into adulthood. The phenotype is associated with dysfunction in a number of systems including paraventricular nucleus of the hypothalamus (PVN responses to psychological and immune stressors. However, in many cases weight gain in neonatally overfed rats stabilizes in early adulthood so the animal does not become more obese as it ages. Here we examined if neonatal overfeeding by suckling rats in small litters predisposes them to exacerbated metabolic and central inflammatory disturbances if they are also given a high fat diet in later life. In adulthood we gave the rats normal chow, 3 days, or 3 weeks high fat diet (45% kcal from fat and measured peripheral indices of metabolic disturbance. We also investigated hypothalamic microglial changes, as an index of central inflammation, as well as PVN responses to lipopolysaccharide (LPS. Surprisingly, neonatal overfeeding did not predispose rats to the metabolic effects of a high fat diet. Weight changes and glucose metabolism were unaffected by the early life experience. However, short term (3 day high fat diet was associated with more microglia in the hypothalamus and a markedly exacerbated PVN response to LPS in control rats; effects not seen in the neonatally overfed. Our findings indicate neonatally overfed animals are not more susceptible to the adverse metabolic effects of a short-term high fat diet but may be less able to respond to the central effects.

  1. Short-term nitrogen dioxide modeling: currently available models and the applications and development needed for energy assessment

    Energy Technology Data Exchange (ETDEWEB)

    Chun, K.C.

    1980-11-01

    The rapid increase in US coal consumption projected for the near future is likely to result in, among other things, increased concentrations of nitrogen dioxide and other nitrogenous pollutants in the ambient atmosphere. The design and siting of new coal utilization facilities could be constrained by the potential promulgation of a short-term ambient air quality standard for nitrogen dioxide and by other regulations. To assess the extent and pattern of such constraints, appropriate air quality models for short-term nitrogen dioxide levels are needed. As an initial step in developing models capable of emissions from coalburning electric utility and industrial point sources, this report: (1) discusses multiple interdependent factors that affect local short-term concentrations of nitrogen dioxide such as meteorology, air quality, and the characteristics and distribution of emission sources of nitrogen dioxide precursors; (2) evaluates the utility and limitations of existing air quality models for nitrogen dioxide, including empirical, mechanistic and empirico-mechanistic models; and (3) suggests an approach for applying and developing relatively simple models for predicting short-term concentrations of nitrogen dioxide in assessments of regional and national energy development.

  2. Influence of High-Current-Density Impulses on the Compression Behavior: Experiments with Iron and a Nickel-Based Alloy

    Science.gov (United States)

    Demler, E.; Gerstein, G.; Dalinger, A.; Epishin, A.; Rodman, D.; Nürnberger, F.

    2017-01-01

    Difficulties of processing of high strength and/or brittle materials by plastic deformation, e.g., by forging, require to develop new industrial technologies. In particular, the feasible deformation rates are limited for low-ductile metallic materials. For this reason, processes were investigated to improve the deformability in which electrical impulses are to be applied to lower the yield strength. However, owing to the impulse duration and low current densities, concomitant effects always occur, e.g., as a result of Joule heating. Current developments in power electronics allow now to transmit high currents as short pulses. By reducing the impulse duration and increasing the current density, the plasticity of metallic materials can be correspondingly increased. Using the examples of polycrystalline iron and a single-crystal, nickel-based alloy (PWA 1480), current advances in the development of methods for forming materials by means of high-current-density impulses are demonstrated. For this purpose, appropriate specimens were loaded in compression and, using novel testing equipment, subjected to a current strength of 10 kA with an impulse duration of 2 ms. For a pre-defined strain, the test results show a significant decrease in the compressive stress during the compression test and a significant change in the dislocation distribution following the current impulse treatment.

  3. Proton-irradiation technology for high-frequency high-current silicon welding diode manufacturing

    Science.gov (United States)

    Lagov, P. B.; Drenin, A. S.; Zinoviev, M. A.

    2017-05-01

    Different proton irradiation regimes were tested to provide more than 20 kHz-frequency, soft reverse recovery “snap-less” behavior, low forward voltage drop and leakage current for 50 mm diameter 7 kA/400 V welding diode Al/Si/Mo structure. Silicon diode with such parameters is very suitable for high frequency resistance welding machines of new generation for robotic welding.

  4. High Field Side Lower Hybrid Current Drive Simulations for Off- axis Current Drive in DIII-D

    Science.gov (United States)

    Wukitch, S. J.; Shiraiwa, S.; Wallace, G. M.; Bonoli, P. T.; Holcomb, C.; Pinsker, R. I.

    2017-10-01

    Efficient off-axis current drive scalable to reactors is a key enabling technology for developing economical, steady state tokamak. Previous studies have focussed on high field side (HFS) launch of lower hybrid current drive (LHCD) in double null configurations in reactor grade plasmas and found improved wave penetration and high current drive efficiency with driven current profile peaked near a normalized radius, ρ, of 0.6-0.8, consistent with advanced tokamak scenarios. Further, HFS launch potentially mitigates plasma material interaction and coupling issues. For this work, we sought credible HFS LHCD scenario for DIII-D advanced tokamak discharges through utilizing advanced ray tracing and Fokker Planck simulation tools (GENRAY+CQL3D) constrained by experimental considerations. For a model and existing discharge, HFS LHCD scenarios with excellent wave penetration and current drive were identified. The LHCD is peaked off axis, ρ˜0.6-0.8, with FWHM Δρ=0.2 and driven current up to 0.37 MA/MW coupled. For HFS near mid plane launch, wave penetration is excellent and have access to single pass absorption scenarios for variety of plasmas for n||=2.6-3.4. These DIII-D discharge simulations indicate that HFS LHCD has potential to demonstrate efficient off axis current drive and current profile control in DIII-D existing and model discharge.

  5. Fast Kicker for High Current Beam Manipulation in Large Aperture

    CERN Document Server

    Gambaryan, V

    2017-01-01

    The pulsed deflecting magnet (kicker) project was worked out in Budker Institute of Nuclear Physics. The kicker design parameters are: impulsive force, 1 mT*m; pulse edge, 5 ns; impulse duration, 200 ns. The unconventional approach is that the plates must be replaced by a set of cylinders. The obtained magnet construction enables the field homogeneity to be controlled by changing current magnitudes in cylinders. Furthermore, we demonstrated the method of field optimization. In addition, measurement technique for the harmonic components was considered and the possibility of control harmonic components value was demonstrated.

  6. Enhancement of High-Intensity Focused Ultrasound Heating by Short-Pulse Generated Cavitation

    Directory of Open Access Journals (Sweden)

    Shin Yoshizawa

    2017-03-01

    Full Text Available A target tissue can be thermally coagulated in high-intensity focused ultrasound (HIFU treatment noninvasively. HIFU thermal treatments have been clinically applied to various solid tumors. One of the problems in HIFU treatments is a long treatment time. Acoustically driven microbubbles can accelerate the ultrasonic heating, resulting in the significant reduction of the treatment time. In this paper, a method named “trigger HIFU exposure” which employs cavitation microbubbles is introduced and its results are reviewed. A trigger HIFU sequence consists of high-intensity short pulses followed by moderate-intensity long bursts. Cavitation bubbles induced in a multiple focal regions by rapidly scanning the focus of high-intensity pulses enhanced the temperature increase significantly and produced a large coagulation region with high efficiency.

  7. Short-term effects of implemented high intensity shoulder elevation during computer work

    DEFF Research Database (Denmark)

    Larsen, Mette K; Samani, Afshin; Madeleine, Pascal

    2009-01-01

    contractions during the computer work. However, it is unknown how this may influence productivity, rate of perceived exertion (RPE) as well as activity and rest of neck-shoulder muscles during computer work. The aim of this study was to investigate short-term effects of a high intensity contraction...... on productivity, RPE and upper trapezius activity and rest during computer work and a subsequent pause from computer work. METHODS: 18 female computer workers performed 2 sessions of 15 min standardized computer mouse work preceded by 1 min pause with and without prior high intensity contraction of shoulder....... RESULTS: The main findings were that a high intensity shoulder elevation did not modify RPE, productivity or EMG activity of the upper trapezius during the subsequent pause and computer work. However, the high intensity contraction reduced the relative rest time of the uppermost (clavicular) trapezius...

  8. High-cadence Hinode/XRT observations for studying coronal events with very short timescales

    Science.gov (United States)

    McKenzie, David Eugene; Kobelski, Adam; Savage, Sabrina

    2017-08-01

    The Hinode X-Ray Telescope’s capability for high time cadence observations makes it an excellent tool for probing highly variable conditions in the corona, including wave-like activity, dynamic plasma motions, and short-duration transient events. XRT is capable of producing images at cadences faster than one image per 10 seconds, which is comparable to the energy release timescales, and/or ionization evolution timescales, predicted by a range of models of coronal activity. In the present work, we demonstrate XRT’s high-cadence capability through observations of active region AR 10923 (2006 November), with cadences of 6-20 seconds. The image sequences, made sequentially with multiple analysis filters, reveal many transient brightenings (i.e., microflares), for which we derive heating and cooling timescales. We also forward model the observed light curves to estimate the temperature, density, filling factors, and lengths of the observed loops. These estimates allow us to prioritize different heating mechanisms, and to better understand the unresolved structures within the observations. This study provides a test of capabilities, which have still not yet been fully utilized by the ten-year-old Hinode X-Ray Telescope, and thus provides a starting point for future investigations of short-timescale/high-frequency variations in coronal X-ray intensity.

  9. Balancing current drive and heating in DIII-D high noninductive current fraction discharges through choice of the toroidal field

    Science.gov (United States)

    Ferron, J. R.; Holcomb, C. T.; Luce, T. C.; Politzer, P. A.; Turco, F.; DeBoo, J. C.; Doyle, E. J.; In, Y.; La Haye, R. J.; Murakami, M.; Okabayashi, M.; Park, J. M.; Petrie, T. W.; Petty, C. C.; Reimerdes, H.

    2011-11-01

    In order to maintain stationary values of the stored energy and the plasma current in a tokamak discharge with all of the current driven noninductively, the sum of the α-heating power and the power required to provide externally driven current must be equal to the power required to maintain the pressure against transport losses. In a study of high noninductive current fraction discharges in the DIII-D tokamak, it is shown that in the case of present-day tokamaks with no α-heating, adjustment of the toroidal field strength (BT) is a tool to obtain this balance between the required current drive and heating powers with other easily modifiable discharge parameters (βN, q95, discharge shape, ne) fixed at values chosen to satisfy specific constraints. With all of the external power sources providing both heating and current drive, and βN and q95 fixed, the fraction of externally driven current scales with BT with little change in the bootstrap current fraction, thus allowing the noninductive current fraction to be adjusted.

  10. Short-course Astronomical Research Seminars for High School and College Students

    Science.gov (United States)

    Johnson, Jolyon

    2011-05-01

    Since 2008, I have helped lead several short-course astronomical research seminars with Russell M. Genet. These seminars have ranged from semester-long courses at Cuesta College in San Luis Obispo, California to long weekends at the University of Oregon's Pine Mountain Observatory. Each seminar is led by an experienced observer or group of observers who guide high school and college students through the scientific process from observations to publication. The students (anywhere from half a dozen to twenty in number) participate in and contribute to every step. Being a coauthor on one or more research papers offers students an advantage on college and scholarship applications. Similarly, graduate schools often prefer students with research experience. Many topics of research are appropriate for these short-courses including variable star, exoplanet, and asteroid photometry. However, the most successful topic has been visual double stars because the observations required are straitforward and the equipment is relatively inexpensive. The Journal of Double Star Observations is also welcoming of student research and provides swift publication. A detailed description of the short-course seminars can be found in the recent Collins Foundation Press volume titled Small Telescopes and Astronomical Research.

  11. Highly sensitive vacuum ion pump current measurement system

    Science.gov (United States)

    Hansknecht, John Christopher [Williamsburg, VA

    2006-02-21

    A vacuum system comprising: 1) an ion pump; 2) power supply; 3) a high voltage DC--DC converter drawing power from the power supply and powering the vacuum pump; 4) a feedback network comprising an ammeter circuit including an operational amplifier and a series of relay controlled scaling resistors of different resistance for detecting circuit feedback; 5) an optional power block section intermediate the power supply and the high voltage DC--DC converter; and 6) a microprocessor receiving feedback information from the feedback network, controlling which of the scaling resistors should be in the circuit and manipulating data from the feedback network to provide accurate vacuum measurement to an operator.

  12. High current nonlinear transmission line based electron beam driver

    Science.gov (United States)

    Hoff, B. W.; French, D. M.; Simon, D. S.; Lepell, P. D.; Montoya, T.; Heidger, S. L.

    2017-10-01

    A gigawatt-class nonlinear transmission line based electron beam driver is experimentally demonstrated. Four experimental series, each with a different Marx bank charge voltage (15, 20, 25, and 30 kV), were completed. Within each experimental series, shots at peak frequencies ranging from 950 MHz to 1.45 GHz were performed. Peak amplitude modulations of the NLTL output voltage signal were found to range between 18% and 35% for the lowest frequency shots and between 5% and 20% for the highest frequency shots (higher modulation at higher Marx charge voltage). Peak amplitude modulations of the electron beam current were found to range between 10% and 20% for the lowest frequency shots and between 2% and 7% for the highest frequency shots (higher modulation at higher Marx charge voltage).

  13. Short-term cooling increases serum triglycerides and small high-density lipoprotein levels in humans.

    Science.gov (United States)

    Hoeke, Geerte; Nahon, Kimberly J; Bakker, Leontine E H; Norkauer, Sabine S C; Dinnes, Donna L M; Kockx, Maaike; Lichtenstein, Laeticia; Drettwan, Diana; Reifel-Miller, Anne; Coskun, Tamer; Pagel, Philipp; Romijn, Fred P H T M; Cobbaert, Christa M; Jazet, Ingrid M; Martinez, Laurent O; Kritharides, Leonard; Berbée, Jimmy F P; Boon, Mariëtte R; Rensen, Patrick C N

    Cold exposure and β3-adrenergic receptor agonism, which both activate brown adipose tissue, markedly influence lipoprotein metabolism by enhancing lipoprotein lipase-mediated catabolism of triglyceride-rich lipoproteins and increasing plasma high-density lipoprotein (HDL) levels and functionality in mice. However, the effect of short-term cooling on human lipid and lipoprotein metabolism remained largely elusive. The objective was to assess the effect of short-term cooling on the serum lipoprotein profile and HDL functionality in men. Body mass index-matched young, lean men were exposed to a personalized cooling protocol for 2 hours. Before and after cooling, serum samples were collected for analysis of lipids and lipoprotein composition by (1)H-nuclear magnetic resonance. Adenosine triphosphate-binding cassette A1 (ABCA1)-mediated cholesterol efflux capacity of HDL was measured using [(3)H]cholesterol-loaded ABCA1-transfected Chinese hamster ovary cells. Short-term cooling increased serum levels of free fatty acids, triglycerides, and cholesterol. Cooling increased the concentration of large very low-density lipoprotein (VLDL) particles accompanied by increased mean size of VLDL particles. In addition, cooling enhanced the concentration of small LDL and small HDL particles as well as the cholesterol levels within these particles. The increase in small HDL was accompanied by increased ABCA1-dependent cholesterol efflux in vitro. Our data show that short-term cooling increases the concentration of large VLDL particles and increases the generation of small LDL and HDL particles. We interpret that cooling increases VLDL production and turnover, which results in formation of surface remnants that form small HDL particles that attract cellular cholesterol. Copyright © 2017 National Lipid Association. Published by Elsevier Inc. All rights reserved.

  14. High risk bladder cancer : current management and survival

    NARCIS (Netherlands)

    Leliveld-Kors, Anna; Bastiaannet, Esther; Doornweerd, Benjamin H J; Schaapveld, Michael; de Jong, Igle J

    2011-01-01

    Purpose: To evaluate the pattern of care in patients with high risk non muscle invasive bladder cancer (NMIBC) in the Comprehensive Cancer Center North-Netherlands (CCCN) and to assess factors associated with the choice of treatment, recurrence and progression free survival rates. Materials and

  15. Current hurdles to the success of high temperature membrane reactors

    NARCIS (Netherlands)

    Saracco, G.; Versteeg, Geert; van Swaaij, Willibrordus Petrus Maria

    1994-01-01

    High-temperature catalytic processs performed using inorganic membranes have been in recent years a fast growing area of research, which seems to have not yet reached its peak. Chemical engineers, catalysts and materials scientists have addressed this topic from different viewpoint in a common

  16. Progress and upgrading of the Heidelberg high current injector

    Indian Academy of Sciences (India)

    gap cavities was built for injection of high intensities of singly charged heavy ions into the Heidelberg heavy ion storage ring TSR. With different ion sources, this system now is used to deliver positive or negative, atomic and molecular ion beams ...

  17. Influence of Ramadan Fasting on Anaerobic Performance and Recovery Following Short time High Intensity Exercise

    OpenAIRE

    Umid Karli; Alpay Guvenc; Alper Aslan; Tahir Hazir; Caner Acikada

    2007-01-01

    The aim of this study was to investigate the effects of Ramadan fasting on anaerobic power and capacity and the removal rate of lactate after short time high intensity exercise in power athletes. Ten male elite power athletes (2 wrestlers, 7 sprinters and 1 thrower, aged 20-24 yr, mean age 22.30 ± 1.25 yr) participated in this study. The subjects were tested three times [3 days before the beginning of Ramadan (Pre-RF), the last 3 days of Ramadan (End-RF) and the last 3 days of the 4th week af...

  18. Very high-capacity short-reach VCSEL systems exploiting multicarrier intensity modulation and direct detection.

    Science.gov (United States)

    Gatto, Alberto; Argenio, Debora; Boffi, Pierpaolo

    2016-06-13

    Multicarrier intensity modulation of a bandwidth-limited long-wavelength VCSEL is exploited combined to direct detection to achieve very high capacity simple systems for short-reach applications. Tailored FDM subcarriers modulation and allocation allow to match the non-uniform frequency response of the system induced by the direct modulation and detection of the FDM signal and by the uncompensated SSMF propagation, overcoming the VCSEL bandwidth limitations. A whole transported throughput ranging from 34 Gb/s to 25 Gb/s from few hundreds meters to 20 km of SSMF propagation is experimentally demonstrated even by employing a 5-GHz band VCSEL source.

  19. Robotic radical prostatectomy in high-risk prostate cancer: current perspectives.

    Science.gov (United States)

    Canda, Abdullah Erdem; Balbay, Mevlana Derya

    2015-01-01

    Around 20%-30% of patients diagnosed with prostate cancer (PCa) still have high-risk PCa disease (HRPC) that requires aggressive treatment. Treatment of HRPC is controversial, and multimodality therapy combining surgery, radiation therapy, and androgen deprivation therapy have been suggested. There has been a trend toward performing radical prostatectomy (RP) in HRPC and currently, robot-assisted laparoscopic RP (RARP) has become the most common approach. Number of publications related to robotic surgery in HRPC is limited in the literature. Tissue and Tumor characteristics might be different in HRPC patients compared to low-risk group and increased surgical experience for RARP is needed. Due to the current literature, RARP seems to have similar oncologic outcomes including surgical margin positivity, biochemical recurrence and recurrence-free survival rates, additional cancer therapy needs and lymph node (LN) yields with similar complication rates compared to open surgery in HRPC. In addition, decreased blood loss, lower rates of blood transfusion and shorter duration of hospital stay seem to be the advantages of robotic surgery in this particular patient group. RARP in HRPC patients seems to be safe and technically feasible with good intermediate-term oncologic results, acceptable morbidities, excellent short-term surgical and pathological outcomes and satisfactory functional results.

  20. Robotic radical prostatectomy in high-risk prostate cancer: current perspectives

    Directory of Open Access Journals (Sweden)

    Abdullah Erdem Canda

    2015-01-01

    Full Text Available Around 20%-30% of patients diagnosed with prostate cancer (PCa still have high-risk PCa disease (HRPC that requires aggressive treatment. Treatment of HRPC is controversial, and multimodality therapy combining surgery, radiation therapy, and androgen deprivation therapy have been suggested. There has been a trend toward performing radical prostatectomy (RP in HRPC and currently, robot-assisted laparoscopic RP (RARP has become the most common approach. Number of publications related to robotic surgery in HRPC is limited in the literature. Tissue and Tumor characteristics might be different in HRPC patients compared to low-risk group and increased surgical experience for RARP is needed. Due to the current literature, RARP seems to have similar oncologic outcomes including surgical margin positivity, biochemical recurrence and recurrence-free survival rates, additional cancer therapy needs and lymph node (LN yields with similar complication rates compared to open surgery in HRPC. In addition, decreased blood loss, lower rates of blood transfusion and shorter duration of hospital stay seem to be the advantages of robotic surgery in this particular patient group. RARP in HRPC patients seems to be safe and technically feasible with good intermediate-term oncologic results, acceptable morbidities, excellent short-term surgical and pathological outcomes and satisfactory functional results.

  1. Electron cyclotron heating/current-drive system using high power tubes for QUEST spherical tokamak

    Science.gov (United States)

    Onchi, Takumi; Idei, H.; Hasegawa, M.; Nagata, T.; Kuroda, K.; Hanada, K.; Kariya, T.; Kubo, S.; Tsujimura, T. I.; Kobayashi, S.; Quest Team

    2017-10-01

    Electron cyclotron heating (ECH) is the primary method to ramp up plasma current non-inductively in QUEST spherical tokamak. A 28 GHz gyrotron is employed for short pulses, where the radio frequency (RF) power is about 300 kW. Current ramp-up efficiency of 0.5 A/W has been obtained with focused beam of the second harmonic X-mode. A quasi-optical polarizer unit has been newly installed to avoid arcing events. For steady-state tokamak operation, 8.56 GHz klystron with power of 200 kW is used as the CW-RF source. The high voltage power supply (54 kV/13 A) for the klystron has been built recently, and initial bench test of the CW-ECH system is starting. The array of insulated-gate bipolar transistor works to quickly cut off the input power for protecting the klystron. This work is supported by JSPS KAKENHI (15H04231), NIFS Collaboration Research program (NIFS13KUTR085, NIFS17KUTR128), and through MEXT funding for young scientists associated with active promotion of national university reforms.

  2. Design of short high-power TE11-HE11 mode converters in highly overmoded corrugated waveguides

    Science.gov (United States)

    Thumm, Manfred; Jacobs, Annemarie; Sorolla Ayza, Mario

    1991-02-01

    A theoretical parametric study of TE11 to HE11 mode conversion in highly oversized, circumferentially corrugated circular waveguides with different inner diameters is presented for various frequencies in the range of 28 to 140 GHz. The depth of the annular slots is tapered gradually from one half to one quarter wavelength. Computer-aided optimization of converter length, shape of corrugations, and nonlinear slot depth variation has been achieved with a scattering matrix code employing the modal field matching techniques (modular analysis concept). Relatively short mode transducers with matched converter lengths are feasible. The optimum conversion lengths are L1 roughly 0.5 lambda(B) (short converter) and L2 roughly 1.2 lambda(B) (long converter), where lambda(B) is the beat wavelength of the TE11 and TM11 modes in the corresponding smooth-walled circular waveguide. The predicted performances of short and long mode transducers are practically identical. Experimental results taken at 70 GHz are in excellent agreement with the theoretically predicted performance data. In all cases the HE11 output mode purity is 99 percent to 99.5 percent. The maximum cross-polarization and input-reflection levels are below -29 dB and -50 dB, respectively.

  3. Brahan Project High Frequency Radar Ocean Measurements: Currents, Winds, Waves and Their Interactions

    Directory of Open Access Journals (Sweden)

    Belinda Lipa

    2014-12-01

    Full Text Available We describe radar measurements of waves, currents and winds made on the coast of northern Scotland during two 2013/14 winter storms, giving methods, results and interpretation. Wave parameters (height, period, direction and short-wave/wind direction were derived and compared with measurements made by a neighboring buoy and local weather stations. Wind direction and current velocity maps were produced and the interactions of winds and currents discussed. Significant oscillations in wave parameters were observed, which appear to be due to forcing by tidal current velocity variations. The oscillations in waveheight are explained using hydrodynamic analysis and derived amplitudes are compared with radar measurements.

  4. Low profile, highly configurable, current sharing paralleled wide band gap power device power module

    Science.gov (United States)

    McPherson, Brice; Killeen, Peter D.; Lostetter, Alex; Shaw, Robert; Passmore, Brandon; Hornberger, Jared; Berry, Tony M

    2016-08-23

    A power module with multiple equalized parallel power paths supporting multiple parallel bare die power devices constructed with low inductance equalized current paths for even current sharing and clean switching events. Wide low profile power contacts provide low inductance, short current paths, and large conductor cross section area provides for massive current carrying. An internal gate & source kelvin interconnection substrate is provided with individual ballast resistors and simple bolted construction. Gate drive connectors are provided on either left or right size of the module. The module is configurable as half bridge, full bridge, common source, and common drain topologies.

  5. High risk bladder cancer: current management and survival

    Directory of Open Access Journals (Sweden)

    Anna M. Leliveld

    2011-04-01

    Full Text Available PURPOSE: To evaluate the pattern of care in patients with high risk non muscle invasive bladder cancer (NMIBC in the Comprehensive Cancer Center North-Netherlands (CCCN and to assess factors associated with the choice of treatment, recurrence and progression free survival rates. MATERIALS AND METHODS: Retrospective analysis of 412 patients with newly diagnosed high risk NMIBC. Clinical, demographic and follow-up data were obtained from the CCCN Cancer Registry and a detailed medical record review. Uni and multivariate analysis was performed to identify factors related to choice of treatment and 5 year recurrence and progression free survival. RESULTS: 74/412 (18% patients with high risk NMIBC underwent a transurethral resection (TUR as single treatment. Adjuvant treatment after TUR was performed in 90.7% of the patients treated in teaching hospitals versus 71.8 % in non-teaching hospitals (p 80 years OR 0.1 p = 0.001 and treatment in non-teaching hospitals (OR 0.25; p < 0.001 were associated with less adjuvant treatment after TUR. Tumor recurrence occurred in 191/392 (49% and progression in 84 /392 (21.4% patients. The mean 5-years progression free survival was 71.6% (95% CI 65.5-76.8. CONCLUSION: In this pattern of care study in high risk NMIBC, 18% of the patients were treated with TUR as single treatment. Age and treatment in non-teaching hospitals were associated with less adjuvant treatment after TUR. None of the variables sex, age, comorbidity, hospital type, stage and year of treatment was associated with 5 year recurrence or progression rates.

  6. Numerical study of the short pre-arcing time in high breaking capacity fuses via an enthalpy formulation

    Energy Technology Data Exchange (ETDEWEB)

    Rochette, David [Laboratoire Arc Electrique et Plasmas thermiques, CNRS UMR 6069, Universite Blaise Pascal-IUT de Montlucon, Avenue Aristide Briand, BP 2235, 03101 Montlucon Cedex (France); Touzani, Rachid [Laboratoire de Mathematiques, CNRS UMR 6620, Universite Blaise Pascal (Clermont-Ferrand II), Campus Universitaire des Cezeaux, 63177 Aubiere Cedex (France); Bussiere, William [Laboratoire Arc Electrique et Plasmas thermiques, CNRS UMR 6069, Universite Blaise Pascal-IUT de Montlucon, Avenue Aristide Briand, BP 2235, 03101 Montlucon Cedex (France)

    2007-08-07

    In order to study the short pre-arcing time in high breaking capacity (HBC) fuses, we use a mathematical model including the phase change of the fuse-element heating coupled with the Laplace equation for the potential and Ohm's law. The thermal model is based on the enthalpy formulation of the heat equation with a source term representing the Joule heating. For the time range considered (up to 10 ms), we assume no heat transfer between the fuse-element and the surrounding sand. To solve numerically the governing equations, we employ a semi-implicit scheme for time integration and a finite element method for space discretization. Using electrical and thermal properties of the silver fuse-element, we present pre-arcing characteristics (temperature, current density, potential) for a fuse-element used in industrial protection circuits.

  7. Proposal for a race-track microtron with high peak current

    NARCIS (Netherlands)

    Ernst, G.J.; Haselhoff, E.H.; Witteman, W.J.; Botman, J.I.M.; van Genderen, W.; Hagedoorn, H.L.; van der Heide, J.A.; Kleeven, W.J.G.M.

    1989-01-01

    In order to obtain high gain in a free electron laser a high-quality electron beam with high peak current is required. It is well-known that a microtron is able to produce a high-quality beam having low emittance and small energy spread (1%). Because a circular microtron has a limited high-current

  8. High-dose irradiated food: Current progress, applications, and prospects

    Science.gov (United States)

    Feliciano, Chitho P.

    2018-03-01

    Food irradiation as an established and mature technology has gained more attention in the food industry for ensuring food safety and quality. Primarily used for phytosanitary applications, its use has been expanded for developing various food products for varied purposes (e.g. ready-to-eat & ready-to-cook foods, hospital diets, etc.). This paper summarized and analyzed the recent progress and application of high-dose irradiation and discussed its prospects in the field of food product development, its safety and quality.

  9. Compact drain-current model for undoped cylindrical surrounding-gate metal-oxide-semiconductor field effect transistors including short channel effects

    Science.gov (United States)

    Smaani, Billel; Latreche, Saida; Iñiguez, Benjamín

    2013-12-01

    In this paper, we present a compact model for undoped short-channel cylindrical surrounding-gate MOSFETs. The drain-current model is expressed as a function of the mobile charge density, which is calculated using the analytical expressions of the surface potential and the difference between surface and center potentials model. The short-channel effects are well incorporated in the drain-current model, such as the drain-induced barrier lowering, the charge sharing effect (VT Roll-off), the subthreshold slope degradation, and the channel length modulation. A comparison of the model results with 3D numerical simulations using Silvaco Atlas-TCAD presents a good agreement from subthreshold to strong inversion regime and for different bias voltages.

  10. Plasma PCSK9 concentrations during an oral fat load and after short term high-fat, high-fat high-protein and high-fructose diets

    Directory of Open Access Journals (Sweden)

    Cariou Bertrand

    2013-01-01

    Full Text Available Abstract Background PCSK9 (Proprotein Convertase Subtilisin Kexin type 9 is a circulating protein that promotes hypercholesterolemia by decreasing hepatic LDL receptor protein. Under non interventional conditions, its expression is driven by sterol response element binding protein 2 (SREBP2 and follows a diurnal rhythm synchronous with cholesterol synthesis. Plasma PCSK9 is associated to LDL-C and to a lesser extent plasma triglycerides and insulin resistance. We aimed to verify the effect on plasma PCSK9 concentrations of dietary interventions that affect these parameters. Methods We performed nutritional interventions in young healthy male volunteers and offspring of type 2 diabetic (OffT2D patients that are more prone to develop insulin resistance, including: i acute post-prandial hyperlipidemic challenge (n=10, ii 4 days of high-fat (HF or high-fat/high-protein (HFHP (n=10, iii 7 (HFruc1, n=16 or 6 (HFruc2, n=9 days of hypercaloric high-fructose diets. An acute oral fat load was also performed in two patients bearing the R104C-V114A loss-of-function (LOF PCSK9 mutation. Plasma PCSK9 concentrations were measured by ELISA. For the HFruc1 study, intrahepatocellular (IHCL and intramyocellular lipids were measured by 1H magnetic resonance spectroscopy. Hepatic and whole-body insulin sensitivity was assessed with a two-step hyperinsulinemic-euglycemic clamp (0.3 and 1.0 mU.kg-1.min-1. Findings HF and HFHP short-term diets, as well as an acute hyperlipidemic oral load, did not significantly change PCSK9 concentrations. In addition, post-prandial plasma triglyceride excursion was not altered in two carriers of PCSK9 LOF mutation compared with non carriers. In contrast, hypercaloric 7-day HFruc1 diet increased plasma PCSK9 concentrations by 28% (p=0.05 in healthy volunteers and by 34% (p=0.001 in OffT2D patients. In another independent study, 6-day HFruc2 diet increased plasma PCSK9 levels by 93% (p Conclusions Plasma PCSK9 concentrations vary

  11. 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.

  12. Advanced concepts for high-power, short-pulse CO2 laser development

    Science.gov (United States)

    Gordon, Daniel F.; Hasson, Victor; von Bergmann, Hubertus; Chen, Yu-hsin; Schmitt-Sody, A.; Penano, Joseph R.

    2016-06-01

    Ultra-short pulse lasers are dominated by solid-state technology, which typically operates in the near-infrared. Efforts to extend this technology to longer wavelengths are meeting with some success, but the trend remains that longer wavelengths correlate with greatly reduced power. The carbon dioxide (CO2) laser is capable of delivering high energy, 10 micron wavelength pulses, but the gain structure makes operating in the ultra-short pulse regime difficult. The Naval Research Laboratory and Air Force Research Laboratory are developing a novel CO2 laser designed to deliver ~1 Joule, ~1 picosecond pulses, from a compact gain volume (~2x2x80 cm). The design is based on injection seeding an unstable resonator, in order to achieve high energy extraction efficiency, and to take advantage of power broadening. The unstable resonator is seeded by a solid state front end, pumped by a custom built titanium sapphire laser matched to the CO2 laser bandwidth. In order to access a broader range of mid infrared wavelengths using CO2 lasers, one must consider nonlinear frequency multiplication, which is non-trivial due to the bandwidth of the 10 micron radiation.

  13. On-current modeling of short-channel double-gate (DG) MOSFETs with a vertical Gaussian-like doping profile

    Science.gov (United States)

    Dubey, Sarvesh; Tiwari, Pramod Kumar; Jit, S.

    2013-05-01

    An analytic drain current model is presented for doped short-channel double-gate MOSFETs with a Gaussian-like doping profile in the vertical direction of the channel. The present model is valid in linear and saturation regions of device operation. The drain current variation with various device parameters has been demonstrated. The model is made more physical by incorporating the channel length modulation effect. Parameters like transconductance and drain conductance that are important in assessing the analog performance of the device have also been formulated. The model results are validated by numerical simulation results obtained by using the commercially available ATLAS™, a two dimensional device simulator from SILVACO.

  14. Analytical modeling on the drain current characteristics of gate-all-around TFET with the incorporation of short-channel effects

    Science.gov (United States)

    Xu, Wanjie; Wong, Hei; Iwai, Hiroshi; Liu, Jun; Qin, Pei

    2017-12-01

    An analytical model for describing the drain current characteristics of gate-all-around (GAA) tunneling field-effect transistor (TFET) is developed. Starting from potential distribution derived from Poisson's equation in different regions along the channel, drain current model is developed based on Kane's approach. The new model shows a better accuracy than the previously reported models. It is valid for larger ranges of bias conditions and channel length also. In particular, we have taken the effect of drain bias on the source junction tunneling into account. This effect is quite significant for the subthreshold conduction of short-channel devices. The validity of this model has been confirmed with TCAD simulation.

  15. Physical mechanisms leading to high currents of highly charged ions in laser-driven ion sources

    Energy Technology Data Exchange (ETDEWEB)

    Haseroth, Helmut [European Organization for Nuclear Research, Geneva (Switzerland); Hora, Heinrich [New South Wales Univ., Kensington, NSW (Australia)]|[Regensburg Inst. of Tech. (Germany). Anwenderzentrum

    1996-12-31

    Heavy ion sources for the big accelerators, for example, the LHC, require considerably more ions per pulse during a short time than the best developed classical ion source, the electron cyclotron resonance (ECR) provides; thus an alternative ion source is needed. This can be expected from laser-produced plasmas, where dramatically new types of ion generation have been observed. Experiments with rather modest lasers have confirmed operation with one million pulses of 1 Hz, and 10{sup 11} C{sup 4+} ions per pulse reached 2 GeV/u in the Dubna synchrotron. We review here the complexities of laser-plasma interactions to underline the unique and extraordinary possibilities that the laser ion source offers. The complexities are elaborated with respect to keV and MeV ion generation, nonlinear (ponderomotive) forces, self-focusing, resonances and ``hot`` electrons, parametric instabilities, double-layer effects, and the few ps stochastic pulsation (stuttering). Recent experiments with the laser ion source have been analyzed to distinguish between the ps and ns interaction, and it was discovered that one mechanism of highly charged ion generation is the electron impact ionization (EII) mechanism, similar to the ECR, but with so much higher plasma densities that the required very large number of ions per pulse are produced. (author).

  16. Comparison of dc and superconducting rf photoemission guns for high brightness high average current beam production

    Directory of Open Access Journals (Sweden)

    Ivan V. Bazarov

    2011-07-01

    Full Text Available A comparison of the two most prominent electron sources of high average current high brightness electron beams, dc and superconducting rf photoemission guns, is carried out using a large-scale multivariate genetic optimizer interfaced with space charge simulation codes. The gun geometry for each case is varied concurrently with laser pulse shape and parameters of the downstream beam line elements of the photoinjector to obtain minimum emittance as a function of bunch charge. Realistic constraints are imposed on maximum field values for the two gun types. The superconducting rf and dc gun emittances and beam envelopes are compared for various values of photocathode thermal emittance. The performance of the two systems is found to be largely comparable for up to 154 pC per bunch at 1.3 GHz or 200 mA provided low intrinsic emittance photocathodes can be employed.

  17. High Voltage Power Supply With High Output Current and Low Power Consumption for Photomultiplier Tubes

    Science.gov (United States)

    Cunha, José Paulo V. S.; Begalli, Marcia; Bellar, Maria Dias

    2012-04-01

    In some applications, photomultiplier tubes (PMTs) are powered by battery based circuits, where the available energy is severely limited. The most simple approach to design high voltage power supplies (HVPS) for PMTs has considered resistive voltage dividers in order to bias the dynodes. However, this approach usually results in high power losses and, consequently, this undermines the PMT performance. In this work, the proposed solution is the use of a power circuit based on the forward converter connected to a transformer built with several secondary windings. Each secondary voltage is rectified and filtered to eliminate voltage ripple. Each dynode voltage is supplied by a rectified secondary voltage. The proposed topology provides low power consumption as well as low sensitivity of the PMT gain with respect to the dynode currents. Taking into account the Waste Electrical and Electronic Equipment Directive (WEEE), this HVPS has been designed to allow the recycling of old PMTs.

  18. Plasma sources for high-current electron beam generation

    Science.gov (United States)

    Krasik, Ya. E.; Dunaevsky, A.; Felsteiner, J.

    2001-05-01

    A review of experimental studies of the operation of cathodes made of metal-ceramic, velvet, corduroy, carbon fibers, carbon fabric, and different types of ferroelectrics is presented. These cathodes operated at electric fields in the range of 5-60 kV/cm that allowed the generation of electron beams with duration of several hundreds of nanoseconds while keeping a quasi-constant diode impedance. All cathodes had the same diameter and were tested in a diode powered by a high-voltage generator (300 kV, 85 Ω, 250 ns, ⩽5 Hz). It was shown that the source of electrons for all the studied cathodes is a plasma which is formed as a result of surface discharges. Different types of electrical and optical diagnostics were used to study the formation and parameters of the plasma, the potential distribution inside the anode-cathode gap, and the uniformity and divergence of the extracted electron beam as a function of the amplitude and rise time of the accelerating pulse. Results of the lifetime of the tested cathodes and their compatibility with vacuum requirements are presented as well.

  19. An ultra short pulse reconstruction software applied to the GEMINI high power laser system

    Energy Technology Data Exchange (ETDEWEB)

    Galletti, Mario, E-mail: mario.gall22@gmail.com [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Galimberti, Marco [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Hooker, Chris [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); University of Oxford, Oxford (United Kingdom); Chekhlov, Oleg; Tang, Yunxin [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Bisesto, Fabrizio Giuseppe [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Curcio, Alessandro [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Sapienza – University of Rome, P.le Aldo Moro, 2, 00185 Rome (Italy); Anania, Maria Pia [INFN – LNF, Via Enrico Fermi 40, 00044 Frascati (Italy); Giulietti, Danilo [Physics Department of the University and INFN, Pisa (Italy)

    2016-09-01

    The GRENOUILLE traces of Gemini pulses (15 J, 30 fs, PW, shot per 20 s) were acquired in the Gemini Target Area PetaWatt at the Central Laser Facility (CLF), Rutherford Appleton Laboratory (RAL). A comparison between the characterizations of the laser pulse parameters made using two different types of algorithms: Video Frog and GRenouille/FrOG (GROG), was made. The temporal and spectral parameters came out to be in great agreement for the two kinds of algorithms. In this experimental campaign it has been showed how GROG, the developed algorithm, works as well as VideoFrog algorithm with the PetaWatt pulse class. - Highlights: • Integration of the diagnostic tool on high power laser. • Validation of the GROG algorithm in comparison to a well-known commercial available software. • Complete characterization of the GEMINI ultra-short high power laser pulse.

  20. High Accuracy mass Measurement of the very Short-Lived Halo Nuclide $^{11}$Li

    CERN Multimedia

    Le scornet, G

    2002-01-01

    The archetypal halo nuclide $^{11}$Li has now attracted a wealth of experimental and theoretical attention. The most outstanding property of this nuclide, its extended radius that makes it as big as $^{48}$Ca, is highly dependent on the binding energy of the two neutrons forming the halo. New generation experiments using radioactive beams with elastic proton scattering, knock-out and transfer reactions, together with $\\textit{ab initio}$ calculations require the tightening of the constraint on the binding energy. Good metrology also requires confirmation of the sole existing precision result to guard against a possible systematic deviation (or mistake). We propose a high accuracy mass determintation of $^{11}$Li, a particularly challenging task due to its very short half-life of 8.6 ms, but one perfectly suiting the MISTRAL spectrometer, now commissioned at ISOLDE. We request 15 shifts of beam time.

  1. Longitudinally excited CO2 laser with short laser pulse operating at high repetition rate

    Science.gov (United States)

    Li, Jianhui; Uno, Kazuyuki; Akitsu, Tetsuya; Jitsuno, Takahisa

    2016-11-01

    A short-pulse longitudinally excited CO2 laser operating at a high repetition rate was developed. The discharge tube was made of a 45 cm-long or 60 cm-long dielectric tube with an inner diameter of 16 mm and two metallic electrodes at the ends of the tube. The optical cavity was formed by a ZnSe output coupler with a reflectivity of 85% and a high-reflection mirror. Mixed gas (CO2:N2:He = 1:1:2) was flowed into the discharge tube. A high voltage of about 33 kV with a rise time of about 200 ns was applied to the discharge tube. At a repetition rate of 300 Hz and a gas pressure of 3.4 kPa, the 45 cm-long discharge tube produced a short laser pulse with a laser pulse energy of 17.5 mJ, a spike pulse energy of 0.2 mJ, a spike width of 153 ns, and a pulse tail length of 90 μs. The output power was 5.3 W. The laser pulse waveform did not depend on the repetition rate, but the laser beam profile did. At a low repetition rate of less than 50 Hz, the laser beam had a doughnut-like shape. However, at a high repetition rate of more than 150 Hz, the discharge concentrated at the center of the discharge tube, and the intensity at the center of the laser beam was higher. The laser beam profile depended on the distribution of the discharge. An output power of 7.0 W was achieved by using the 60 cm-long tube.

  2. High current multicharged metal ion source using high power gyrotron heating of vacuum arc plasma.

    Science.gov (United States)

    Vodopyanov, A V; Golubev, S V; Khizhnyak, V I; Mansfeld, D A; Nikolaev, A G; Oks, E M; Savkin, K P; Vizir, A V; Yushkov, G Yu

    2008-02-01

    A high current, multi charged, metal ion source using electron heating of vacuum arc plasma by high power gyrotron radiation has been developed. The plasma is confined in a simple mirror trap with peak magnetic field in the plug up to 2.5 T, mirror ratio of 3-5, and length variable from 15 to 20 cm. Plasma formed by a cathodic vacuum arc is injected into the trap either (i) axially using a compact vacuum arc plasma gun located on axis outside the mirror trap region or (ii) radially using four plasma guns surrounding the trap at midplane. Microwave heating of the mirror-confined, vacuum arc plasma is accomplished by gyrotron microwave radiation of frequency 75 GHz, power up to 200 kW, and pulse duration up to 150 micros, leading to additional stripping of metal ions by electron impact. Pulsed beams of platinum ions with charge state up to 10+, a mean charge state over 6+, and total (all charge states) beam current of a few hundred milliamperes have been formed.

  3. Hard plastic cladding fiber (HPCF) based optical components for high speed short reach optical communications

    Science.gov (United States)

    Kim, Jun Ki; Kim, Dong Uk; Kim, Tae Young; Park, Chang Soo; Oh, Kyunghwan

    2006-09-01

    We developed the primary components applicable to HPCF links for short reach (SR) and very short reach (VSR) data communication systems. We fabricated 4x4 HPCF fused taper splitter, HPCF pigtailed VCSEL and PIN photodiode for high speed short reach communications and characterized back to back transmission performance of the link composed of these components by measuring eye diagrams and jitters. Adapting the fusion-tapering technique for glass optical fiber, we successfully fabricated a 4x4 HPCF fused taper coupler. The HPCF with a core diameter of 200μm and an outer diameter of 230μm had step refractive index of 1.45 and 1.40 for the core and the clad. The optimized fusion length and tapering waist which make minimum insertion loss of about 7dB and uniform output power splitting ratio with less than 0.5dB are 13mm and 150µm, respectively. As a light source for VSR networks, we chose a vertical cavity surface emitting laser (VCSEL) and developed a package with a HPCF pigtail. After positioning VCSEL and HPCF that made a minimum coupling loss, we glued the HPCF inside ceramic ferrule housing. In HPCF-PIN PD packaging, we added a micro polymer lens tip onto the HPCF ends to match the mode field area to the sensitive area of GaAs or InGaAs PIN PD. Coupling between a PIN PD chip and the lensed HPCF was optimized with the radius of curvature of 156µm with a low coupling loss of 0.3dB, which is compatible to conventional MMF-PD packaging. For 1.25 Gbps data rate, the eyes adequate to eye mask in gigabit Ethernet were wide open after all HPCF transmission link and no significant power penalty was observed.

  4. Combined passive detection and ultrafast active imaging of cavitation events induced by short pulses of high-intensity ultrasound

    Science.gov (United States)

    Gateau, Jérôme; Aubry, Jean-François; Pernot, Mathieu; Fink, Mathias; Tanter, Mickaël

    2011-01-01

    The activation of natural gas nuclei to induce larger bubbles is possible using short ultrasonic excitations of high amplitude, and is required for ultrasound cavitation therapies. However, little is known about the distribution of nuclei in tissues. Therefore, the acoustic pressure level necessary to generate bubbles in a targeted zone and their exact location are currently difficult to predict. In order to monitor the initiation of cavitation activity, a novel all-ultrasound technique sensitive to single nucleation events is presented here. It is based on combined passive detection and ultrafast active imaging over a large volume and with the same multi-element probe. Bubble nucleation was induced with a focused transducer (660kHz, f#=1) driven by a high power (up to 300 W) electric burst of one to two cycles. Detection was performed with a linear array (4–7MHz) aligned with the single-element focal point. In vitro experiments in gelatin gel and muscular tissue are presented. The synchronized passive detection enabled radio-frequency data to be recorded, comprising high-frequency coherent wave fronts as signatures of the acoustic emissions linked to the activation of the nuclei. Active change detection images were obtained by subtracting echoes collected in the unucleated medium. These indicated the appearance of stable cavitating regions. Thanks to the ultrafast frame rate, active detection occurred as soon as 330 μs after the high amplitude excitation and the dynamics of the induced regions were studied individually. PMID:21429844

  5. Short-term effects of implemented high intensity shoulder elevation during computer work

    Directory of Open Access Journals (Sweden)

    Madeleine Pascal

    2009-08-01

    Full Text Available Abstract Background Work-site strength training sessions are shown effective to prevent and reduce neck-shoulder pain in computer workers, but difficult to integrate in normal working routines. A solution for avoiding neck-shoulder pain during computer work may be to implement high intensity voluntary contractions during the computer work. However, it is unknown how this may influence productivity, rate of perceived exertion (RPE as well as activity and rest of neck-shoulder muscles during computer work. The aim of this study was to investigate short-term effects of a high intensity contraction on productivity, RPE and upper trapezius activity and rest during computer work and a subsequent pause from computer work. Methods 18 female computer workers performed 2 sessions of 15 min standardized computer mouse work preceded by 1 min pause with and without prior high intensity contraction of shoulder elevation. RPE was reported, productivity (drawings per min measured, and bipolar surface electromyography (EMG recorded from the dominant upper trapezius during pauses and sessions of computer work. Repeated measure ANOVA with Bonferroni corrected post-hoc tests was applied for the statistical analyses. Results The main findings were that a high intensity shoulder elevation did not modify RPE, productivity or EMG activity of the upper trapezius during the subsequent pause and computer work. However, the high intensity contraction reduced the relative rest time of the uppermost (clavicular trapezius part during the subsequent pause from computer work (p Conclusion Since a preceding high intensity shoulder elevation did not impose a negative impact on perceived effort, productivity or upper trapezius activity during computer work, implementation of high intensity contraction during computer work to prevent neck-shoulder pain may be possible without affecting the working routines. However, the unexpected reduction in clavicular trapezius rest during a

  6. Short-pulse, high-energy radiation generation from laser-wakefield accelerated electron beams

    Science.gov (United States)

    Schumaker, Will

    2013-10-01

    Recent experimental results of laser wakefield acceleration (LWFA) of ~GeV electrons driven by the 200TW HERCULES and the 400TW ASTRA-GEMINI laser systems and their subsequent generation of photons, positrons, and neutrons are presented. In LWFA, high-intensity (I >1019 W /cm2), ultra-short (τL counter-propagating, ultra-high intensity (I >1021 W /cm2) laser pulse to undergo inverse Compton scattering and emit a high-peak brightness beam of high-energy photons. Preliminary results and experimental sensitivities of the electron-laser beam overlap are presented. The high-energy photon beams can be spectrally resolved using a forward Compton scattering spectrometer. Moreover, the photon flux can be characterized by a pixelated scintillator array and by nuclear activation and (γ,n) neutron measurements from the photons interacting with a secondary solid target. Monte-Carlo simulations were performed using FLUKA to support the yield estimates. This research was supported by DOE/NSF-PHY 0810979, NSF CAREER 1054164, DARPA AXiS N66001-11-1-4208, SF/DNDO F021166, and the Leverhulme Trust ECF-2011-383.

  7. Highly Sensitive Measurements of the Dark Current of Superconducting Cavities for TESLA Using a SQUID Based Cryogenic Current Comparator

    CERN Document Server

    Vodel, W; Nietzsche, S

    2004-01-01

    This contribution presents a Cryogenic Current Comparator (CCC) as an excellent tool for detecting dark currents generated, e.g. by superconducting cavities for the upcoming TESLA project (X-FEL) at DESY. To achieve the maximum possible energy the gradient of the superconducting RF cavities should be pushed close to the physical limit of 50 MV/m. The undesired field emission of electrons (so-called dark current) of the superconducting RF cavities at strong fields may limit the maximum gradient. The absolute measurement of the dark current in correlation with the gradient will give a proper value to compare and classify the cavities. The main component of the CCC is a highly sensitive LTS-DC SQUID system which is able to measure extremely low magnetic fields, e.g. caused by the dark current. For this reason the input coil of the SQUID is connected across a special designed toroidal niobium pick-up coil for the passing electron beam. A noise limited current resolution of nearly 2 pA/√(Hz) with a measu...

  8. Short-term natural history of high-risk human papillomavirus infection in mid-adult women sampled monthly.

    Science.gov (United States)

    Fu, Tsung-chieh Jane; Fu Xi, Long; Hulbert, Ayaka; Hughes, James P; Feng, Qinghua; Schwartz, Stephen M; Hawes, Stephen E; Koutsky, Laura A; Winer, Rachel L

    2015-11-15

    Characterizing short-term HPV detection patterns and viral load may inform HPV natural history in mid-adult women. From 2011-2012, we recruited women aged 30-50 years. Women submitted monthly self-collected vaginal samples for high-risk HPV DNA testing for 6 months. Positive samples were tested for type-specific HPV DNA load by real-time PCR. HPV type-adjusted linear and Poisson regression assessed factors associated with (i) viral load at initial HPV detection and (ii) repeat type-specific HPV detection. One-hundred thirty-nine women (36% of 387 women with ≥4 samples) contributed 243 type-specific HR HPV infections during the study; 54% of infections were prevalent and 46% were incident. Incident (vs. prevalent) detection and past pregnancy were associated with lower viral load, whereas current smoking was associated with higher viral load. In multivariate analysis, current smoking was associated with a 40% (95% CI: 5-87%) increase in the proportion of samples that were repeatedly positive for the same HPV type, whereas incident (vs. prevalent) detection status and past pregnancy were each associated with a reduction in the proportion of samples repeatedly positive (55%, 95% CI: 38-67% and 26%, 95% CI: 10-39%, respectively). In a separate multivariate model, each log10 increase in viral load was associated with a 10% (95% CI: 4-16%) increase in the proportion of samples repeatedly positive. Factors associated with repeat HPV detection were similar to those observed in longer-term studies, suggesting that short-term repeat detection may relate to long-term persistence. The negative associations between incident HPV detection and both viral load and repeat detection suggest that reactivation or intermittent persistence was more common than new acquisition. © 2015 UICC.

  9. High-resolution 1 H-MRSI of the brain using short-TE SPICE.

    Science.gov (United States)

    Ma, Chao; Lam, Fan; Ning, Qiang; Johnson, Curtis L; Liang, Zhi-Pei

    2017-02-01

    To improve signal-to-noise ratio (SNR) for high-resolution spectroscopic imaging using a subspace-based technique known as SPectroscopic Imaging by exploiting spatiospectral CorrElation (SPICE). The proposed method is based on a union-of-subspaces model of MRSI signals, which exploits the partial separability properties of water, lipid, baseline and metabolite signals. Enabled by this model, a special scheme is used for accelerated data acquisition, which includes a double-echo CSI component used to collect a "training" dataset (for determination of the basis functions) and a short-TE EPSI component used to collect a sparse "imaging" dataset (for determination of the overall spatiospectral distributions). A set of signal processing algorithms are developed to remove the water and lipid signals and jointly reconstruct the metabolite and baseline signals. In vivo 1 H-MRSI results show that the proposed method can effectively remove the remaining water and lipid signals from sparse MRSI data acquired at 20 ms TE. Spatiospectral distributions of metabolite signals at 2 mm in-plane resolution with good SNR were obtained in a 15.5 min scan. The proposed method can effectively remove nuisance signals and reconstruct high-resolution spatiospectral functions from sparse data to make short-TE SPICE possible. The method should prove useful for high-resolution 1 H-MRSI of the brain. Magn Reson Med 77:467-479, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  10. Short- versus long-term prediction of dementia among subjects with low and high educational levels.

    Science.gov (United States)

    Chary, Emilie; Amieva, Hélène; Pérès, Karine; Orgogozo, Jean-Marc; Dartigues, Jean-François; Jacqmin-Gadda, Hélène

    2013-09-01

    Using simple measures of cognition and disability in a prospective community-living cohort of normal elderly persons, the main objectives of our study were to distinguish short- and long-term predictors for dementia according to educational level and to propose a tool for early detection of subjects at high risk of dementia. Data derived from the French cohort study Paquid (Personnes Agées QUID), which included 3777 subjects, older than 65 years of age, who were followed for a 20-year period. The risk of dementia at 3 years and 10 years was estimated by logistic regression for repeated measures combining data from all the 3- and 10-year windows throughout the follow-up. Predictors included disability assessed by the number of dependent items among four instrumental activities of daily living (IADLs), four neuropsychological tests, five Mini-Mental State Examination (MMSE) subtests, and four items of subjective memory complaints. Of the 2882 included subjects, the number of IADLs remained a predictor of short- and long-term conversion to dementia for those with low educational level (combined with only one cognitive test) whereas the best predictors for more educated subjects combined subjective memory complaints and memory and executive function tests. The episodic memory subtest was the only predictive MMSE subtest. In the high-education-level group, the areas under the receiver-operating characteristic curve of the selected models were 0.85 for 3-year prediction and 0.78 for 10-year prediction. Early predictors of dementia are different according to educational level. Among subjects reaching the secondary school level, early detection of those at high risk of dementia is possible with good predictive performance, with a few simple objective and subjective cognitive evaluations. Copyright © 2013 The Alzheimer's Association. Published by Elsevier Inc. All rights reserved.

  11. Reflectivity of plasmas created by high-intensity, ultra-short laser pulses

    Energy Technology Data Exchange (ETDEWEB)

    Gold, David Michael [Univ. of California, Davis, CA (United States)

    1994-06-01

    Experiments were performed to characterize the creation and evolution of high-temperature (T e~100eV), high-density (ne>1022cm-3) plasmas created with intense (~1012-1016W/cm2), ultra-short (130fs) laser pulses. The principle diagnostic was plasma reflectivity at optical wavelengths (614nm). An array of target materials (Al, Au, Si, SiO2) with widely differing electronic properties tested plasma behavior over a large set of initial states. Time-integrated plasma reflectivity was measured as a function of laser intensity. Space- and time-resolved reflectivity, transmission and scatter were measured with a spatial resolution of ~3μm and a temporal resolution of 130fs. An amplified, mode-locked dye laser system was designed to produce ~3.5mJ, ~130fs laser pulses to create and nonintrusively probe the plasmas. Laser prepulse was carefully controlled to suppress preionization and give unambiguous, high-density plasma results. In metals (Al and Au), it is shown analytically that linear and nonlinear inverse Bremsstrahlung absorption, resonance absorption, and vacuum heating explain time-integrated reflectivity at intensities near 1016W/cm2. In the insulator, SiO2, a non-equilibrium plasma reflectivity model using tunneling ionization, Helmholtz equations, and Drude conductivity agrees with time-integrated reflectivity measurements. Moreover, a comparison of ionization and Saha equilibration rates shows that plasma formed by intense, ultra-short pulses can exist with a transient, non-equilibrium distribution of ionization states. All targets are shown to approach a common reflectivity at intensities ~1016W/cm2, indicating a material-independent state insensitive to atomic or solid-state details.

  12. Evaluating the relationship between breakfast pattern and short-term memory in junior high school girls.

    Science.gov (United States)

    Ahmadi, A; Sohrabi, Z; Eftekhari, M H

    2009-05-01

    The aim of this study was to evaluate the relationship between breakfast pattern and short-term memory in guidance-school students. Memory improves for subjects who have eaten breakfast. It appears that breakfast consumption influences cognition via several mechanisms. What children eat for breakfast before going to school is very important. A total of 150 junior high school girls were taken from a subject pool in four schools in Shiraz (capital of the Fars Province in Iran). They filled out the socio-economic questionnaires as well as food frequency questionnaires for breakfast and provided two-three day breakfast records in two different seasons and their short-term memories were evaluated by Weksler test socio-economic conditions and dietary intakes were analyzed. The results of the study showed that there was no correlation between parents job, students mean age and their school grades with their memory scores. Dietary analysis demonstrated a negative correlation between local soup consumption in breakfast and memory scores. Food record analysis showed no correlation between fat, cholesterol, protein, vitamin B6, B12, calorie and iodine intake in breakfast and memory scores, but there was a positive correlation between carbohydrate, iron and vitamin B3 intake in breakfast and memory scores, similarly there was a positive correlation between B12 intake in the breakfast and students' average school grades during the year.

  13. Quercetin alleviates inflammation after short-term treatment in high-fat-fed mice.

    Science.gov (United States)

    Das, Nilanjan; Sikder, Kunal; Bhattacharjee, Surajit; Majumdar, Suchandra Bhattacharya; Ghosh, Santinath; Majumdar, Subrata; Dey, Sanjit

    2013-06-01

    Consumption of a high-fat diet (HFD) promotes reactive oxygen species (ROS) which ultimately trigger inflammation. The aim of this study was to investigate the role of Moringa oleifera leaf extract (MoLE) and its active component quercetin in preventing NF-κB-mediated inflammation raised by short-term HFD. Quercetin was found to be one of the major flavonoid components from HPLC of MoLE. Swiss mice were fed for 15 days on HFD, both with or without MoLE/quercetin. The antioxidant profile was estimated from liver homogenate. NF-κB and some relevant inflammatory markers were evaluated by immunoblotting, RT-PCR and ELISA. Significantly (P < 0.05) lower antioxidant profile and higher lipid peroxidation was found in HFD group compared to control (P < 0.05). Increased nuclear import of NF-κB and elevated expressions of pro-inflammatory markers were further manifestations in the HFD group. All these changes were reversed in the MoLE/quercetin-treated groups with significant improvement of antioxidant activity compared to the HFD group. MoLE was found to be rich in polyphenols and both MoLE and quercetin showed potent free radical and hydroxyl radical quenching activity. Thus, the present study concluded that short-term treatment with MoLE and its constituent quercetin prevent HFD-mediated inflammation in mice.

  14. Effects of High Intensity White Noise on Short-Term Memory for Position in a List and Sequence

    Science.gov (United States)

    Daee, Safar; Wilding, J. M.

    1977-01-01

    Seven experiments are described investigating the effecy of high intensity white noise during the visual presentation of words on a number of short-term memory tasks. Examines results relative to position learning and sequence learning. (Editor/RK)

  15. Short-term effects of implemented high intensity shoulder elevation during computer work.

    Science.gov (United States)

    Larsen, Mette K; Samani, Afshin; Madeleine, Pascal; Olsen, Henrik B; Søgaard, Karen; Holtermann, Andreas

    2009-08-10

    Work-site strength training sessions are shown effective to prevent and reduce neck-shoulder pain in computer workers, but difficult to integrate in normal working routines. A solution for avoiding neck-shoulder pain during computer work may be to implement high intensity voluntary contractions during the computer work. However, it is unknown how this may influence productivity, rate of perceived exertion (RPE) as well as activity and rest of neck-shoulder muscles during computer work. The aim of this study was to investigate short-term effects of a high intensity contraction on productivity, RPE and upper trapezius activity and rest during computer work and a subsequent pause from computer work. 18 female computer workers performed 2 sessions of 15 min standardized computer mouse work preceded by 1 min pause with and without prior high intensity contraction of shoulder elevation. RPE was reported, productivity (drawings per min) measured, and bipolar surface electromyography (EMG) recorded from the dominant upper trapezius during pauses and sessions of computer work. Repeated measure ANOVA with Bonferroni corrected post-hoc tests was applied for the statistical analyses. The main findings were that a high intensity shoulder elevation did not modify RPE, productivity or EMG activity of the upper trapezius during the subsequent pause and computer work. However, the high intensity contraction reduced the relative rest time of the uppermost (clavicular) trapezius part during the subsequent pause from computer work (p shoulder elevation did not impose a negative impact on perceived effort, productivity or upper trapezius activity during computer work, implementation of high intensity contraction during computer work to prevent neck-shoulder pain may be possible without affecting the working routines. However, the unexpected reduction in clavicular trapezius rest during a pause with preceding high intensity contraction requires further investigation before high

  16. Current density and catalyst-coated membrane resistance distribution of hydro-formed metallic bipolar plate fuel cell short stack with 250 cm2 active area

    Science.gov (United States)

    Haase, S.; Moser, M.; Hirschfeld, J. A.; Jozwiak, K.

    2016-01-01

    An automotive fuel cell with an active area of 250 cm2 is investigated in a 4-cell short stack with a current and temperature distribution device next to the bipolar plate with 560 current and 140 temperature segments. The electrical conductivities of the bipolar plate and gas diffusion layer assembly are determined ex-situ with this current scan shunt module. The applied fuel cell consists of bipolar plates constructed of 75-μm-thick, welded stainless-steel foils and a graphitic coating. The electrical conductivities of the bipolar plate and gas diffusion layer assembly are determined ex-situ with this module with a 6% deviation in in-plane conductivity. The current density distribution is evaluated up to 2.4 A cm-2. The entire cell's investigated volumetric power density is 4.7 kW l-1, and its gravimetric power density is 4.3 kW kg-1 at an average cell voltage of 0.5 V. The current density distribution is determined without influencing the operating cell. In addition, the current density distribution in the catalyst-coated membrane and its effective resistivity distribution with a finite volume discretisation of Ohm's law are evaluated. The deviation between the current density distributions in the catalyst-coated membrane and the bipolar plate is determined.

  17. CALCULATION AND EXPERIMENTAL ESTIMATION OF RESULTS OF ELECTRO-THERMAL ACTION OF RATIONED BY THE INTERNATIONAL STANDARD IEC 62305-1-2010 IMPULSE CURRENT OF SHORT BLOW OF ARTIFICIAL LIGHTNING ON THE THIN-WALLED COVERAGE FROM STAINLESS STEEL

    Directory of Open Access Journals (Sweden)

    M. I. Baranov

    2017-03-01

    Full Text Available Purpose. Calculation and experimental researches of electro-thermal resistibility of the pre-production thin-walled sheet models of outward roof of height technical buildings from stainless steel are easily soiled 12Х18Н10Т to direct action on them rationed by the International Standard IEC 62305-1-2010 aperiodic impulse of current of short bow of artificial lightning of temporal form 10/350 μs with the proper admittances on his peak-temporal parameters (PTP. Methodology. Electrophysics bases of technique of high voltage and large impulsive currents (LIC, and also scientific and technical bases of planning of high-voltage impulsive devices and measuring methods in them LIC with followings below extreme PTP: amplitude of impulse of current of ImL=200 кА (with admittance ±10 %; integral of action of impulse of current of JL=10·106 A2·s (with admittance ±35 %; %; duration of wavefront current of T1=10 μs (with admittance ±20 %; time, proper amplitude of impulse of current of ImL, tmL≤24 μs (with admittance ±20 %; duration of flowing of impulse of current of T2=350 μs (with admittance ±10 %. Results. The results of evaluation calculation and experimental researches of electro-thermal resistibility of the indicated pre-production sheet models are resulted measuring in the plan of 0,5 x 0,5 m from stainless steel are easily soiled the 12Х18Н10Т thickness of 1 mm to action on them of aperiodic impulse of current of short blow of artificial lightning with rationed PTP on the requirements of the International Standard IEC 62305-1-2010. In high current experiments amplitude of ImL of the aperiodic rationed impulse of current of artificial lightning of temporal form of T1/T2=15 μs/315 μs changed in the range of (100-184 кА. The integral of action of JL of impulse of current for I-IV of levels of protection of lightning of technical objects (TO numeral made from 2,32·106 А2·s to 7,88·106 А2·s, and the flowing through the

  18. A linearly controlled direct-current power source for high-current inductive loads in a magnetic suspension wind tunnel

    Science.gov (United States)

    Tripp, John S.; Daniels, Taumi S.

    1990-08-01

    The NASA Langley 6 inch magnetic suspension and balance system (MSBS) requires an independently controlled bidirectional DC power source for each of six positioning electromagnets. These electromagnets provide five-degree-of-freedom control over a suspended aerodynamic test model. Existing power equipment, which employs resistance coupled thyratron controlled rectifiers as well as AC to DC motor generator converters, is obsolete, inefficient, and unreliable. A replacement six phase bidirectional controlled bridge rectifier is proposed, which employs power MOSFET switches sequenced by hybrid analog/digital circuits. Full load efficiency is 80 percent compared to 25 percent for the resistance coupled thyratron system. Current feedback provides high control linearity, adjustable current limiting, and current overload protection. A quenching circuit suppresses inductive voltage impulses. It is shown that 20 kHz interference from positioning magnet power into MSBS electromagnetic model position sensors results predominantly from capacitively coupled electric fields. Hence, proper shielding and grounding techniques are necessary. Inductively coupled magnetic interference is negligible.

  19. A linearly controlled direct-current power source for high-current inductive loads in a magnetic suspension wind tunnel

    Science.gov (United States)

    Tripp, John S.; Daniels, Taumi S.

    1990-01-01

    The NASA Langley 6 inch magnetic suspension and balance system (MSBS) requires an independently controlled bidirectional DC power source for each of six positioning electromagnets. These electromagnets provide five-degree-of-freedom control over a suspended aerodynamic test model. Existing power equipment, which employs resistance coupled thyratron controlled rectifiers as well as AC to DC motor generator converters, is obsolete, inefficient, and unreliable. A replacement six phase bidirectional controlled bridge rectifier is proposed, which employs power MOSFET switches sequenced by hybrid analog/digital circuits. Full load efficiency is 80 percent compared to 25 percent for the resistance coupled thyratron system. Current feedback provides high control linearity, adjustable current limiting, and current overload protection. A quenching circuit suppresses inductive voltage impulses. It is shown that 20 kHz interference from positioning magnet power into MSBS electromagnetic model position sensors results predominantly from capacitively coupled electric fields. Hence, proper shielding and grounding techniques are necessary. Inductively coupled magnetic interference is negligible.

  20. Current status of the mudskipper Periophthalmus modestus (family: Gobiidae) in Hiroshima Prefecture, Seto Inland Sea, Japan <Short Report>

    OpenAIRE

    清水, 則雄; 内藤, 順一; 大塚, 攻; 坂井, 陽一; 橋本, 博明

    2011-01-01

    The Japanese mudskipper, Periophthalmus modestus, is classified as a semi-endangered species on the red list (2007) for estuarine and freshwater fishes published by the Ministry of the Environment. Information on the mudskipper in Hiroshima Prefecture is extremely scarce and it is not published in the red data book (2004) on Hiroshima Prefecture. To determine the current habitat of P. modestus, we surveyed 9 mudflat areas (including areas where the mudskipper had lived in the past) in Hiroshi...

  1. High Performance Short-Channel Organic Field-Effect Transistors with Graphene Electrodes

    Science.gov (United States)

    Kang, Narae; Khondaker, Saiful I.

    2015-03-01

    Organic Field-Effect Transistors (OFETs) have received a great deal of attention due to their easy-processing, low-cost, flexibility, and transparency that can lead to future electronic applications such as flexible display, solar cell, and sensors. One of the major challenges in fabricating high-performance OFETs is to reduce a large injection barrier formed at metal/organic interface, which results in poor electrical transport performance. In order to overcome this issue, graphene has been suggested as a promising electrode material for OFETs due to its unique electronic properties as well as strong π- π interaction with organic molecule, which can reduce the injection barrier at the electrode/organic interface. In this study, we fabricated short-channel OEFTs using mechanically exfoliated graphene electrodes, and performed temperature dependent transport studies. We will present the detailed temperature dependent data and discuss the charge carrier injection mechanism at graphene/organic interface. US NSF Grant No. ECCS 1102228.

  2. Construction of Short-Length High-Rates LDPC Codes Using Difference Families

    Directory of Open Access Journals (Sweden)

    Deny Hamdani

    2010-10-01

    Full Text Available Low-density parity-check (LDPC code is linear-block error-correcting code defined by sparse parity-check matrix. It is decoded using the massage-passing algorithm, and in many cases, capable of outperforming turbo code. This paper presents a class of low-density parity-check (LDPC codes showing good performance with low encoding complexity. The code is constructed using difference families from  combinatorial design. The resulting code, which is designed to have short code length and high code rate, can be encoded with low complexity due to its quasi-cyclic structure, and performs well when it is iteratively decoded with the sum-product algorithm. These properties of LDPC code are quite suitable for applications in future wireless local area network.

  3. High power, short pulses ultraviolet laser for the development of a new x-ray laser

    Energy Technology Data Exchange (ETDEWEB)

    Meixler, L.; Nam, C.H.; Robinson, J.; Tighe, W.; Krushelnick, K.; Suckewer, S.; Goldhar, J.; Seely, J.; Feldman, U.

    1989-04-01

    A high power, short pulse ultraviolet laser system (Powerful Picosecond-Laser) has been developed at the Princeton Plasma Physics Laboratory (PPPL) as part of experiments designed to generate shorter wavelength x-ray lasers. With the addition of pulse compression and a final KrF amplifier the laser output is expected to have reached 1/3-1/2 TW (10/sup 12/ watts) levels. The laser system, particularly the final amplifier, is described along with some initial soft x-ray spectra from laser-target experiments. The front end of the PP-Laser provides an output of 20--30 GW (10/sup 9/ watts) and can be focussed to intensities of /approximately/10/sup 16/ W/cm/sup 2/. Experiments using this output to examine the effects of a prepulse on laser-target interaction are described. 19 refs., 14 figs.

  4. Scar resurfacing with high-energy, short-pulsed and flashscanning carbon dioxide lasers.

    Science.gov (United States)

    Bernstein, L J; Kauvar, A N; Grossman, M C; Geronemus, R G

    1998-01-01

    Scars have a significant effect on a person's physical and social being. Many treatment modalities for scar improvement such as surgical scar revision, electrosurgical planing, chemical peeling, filler substance implantation, and dermabrasion have been developed. Recently, the resurfacing carbon dioxide (CO2) laser systems have proven to be a useful and safe treatment in the treatment of facial rhytides and acne scarring. The purpose of this study was to evaluate the resurfacing CO2 lasers in the treatment of various surgical, traumatic, acne, and varicella scars. Thirty subjects, aging between 14 and 84 years, with surgical, traumatic, acne, or varicella scars were evaluated. Two types of resurfacing laser systems were utilized in this study, a high-energy, short-pulsed CO2 laser and a continuous wave CO2 laser with an optico-mechanical computer flash-scanner. Post-surgical scars were treated with laser resurfacing between 4 and 6 weeks after scar formation. Traumatic, acne, and varicella scars were treated after scar maturation (range, 1-10 years). Scar improvement was evaluated by photographic analysis of before and after images by four independent health care workers using a quartile scale of improvement ( 75%) as well as optical profilometry using silicone surface impressions in 12 scars. Twenty of 24 surgical scars had greater than 75% improvement, and 24 of 24 had greater than 50% improvement by photographic analysis. All six traumatic, acne and varicella scars had greater than 50% improvement. Optical profilometry and surface topography maps reveal a significant flattening of related and depressed scars. The high-energy, short-pulsed CO2 laser and the continuous wave CO2 laser with flash-scanning attachment are safe and effective as a treatment modality for scar revision. In general, elevated scars improve more dramatically than depressed scars.

  5. A high-current rail-type gas switch with preionization by an additional corona discharge

    Energy Technology Data Exchange (ETDEWEB)

    Antipov, E. I.; Belozerov, O. S.; Krastelev, E. G., E-mail: ekrastelev@yandex.ru [National Research Nuclear University MEPhI (Moscow Engineering Physics Institute) (Russian Federation)

    2016-12-15

    The characteristics of a high-current rail-type gas switch with preionization of the gas (air) in a spark gap by an additional corona discharge are investigated. The experiments were performed in a voltage range of 10–45 kV using a two-electrode switch consisting of two cylindrical electrodes with a diameter of 22 mm and a length of 100 mm and a set of laterally located corona-discharge needles. The requirements for the position and size of the needles are defined for which a corona discharge is ignited before a breakdown of the main gap and does not change to a sparking form, and the entire length of the rail electrodes is efficiently used. The fulfillment of these requirements ensures stable operation of the switch with a small variation of the pulse breakdown voltage, which is not more than 1% for a fixed voltage-pulse rise time in the range from 150 ns to 3.5 μs. A short delay time of the switch breakdown makes it possible to control the two-electrode switch by an overvoltage pulse of nanosecond duration.

  6. Ain't no mountain high enough? Setting high weight loss goals predict effort and short-term weight loss.

    Science.gov (United States)

    De Vet, Emely; Nelissen, Rob M A; Zeelenberg, Marcel; De Ridder, Denise T D

    2013-05-01

    Although psychological theories outline that it might be beneficial to set more challenging goals, people attempting to lose weight are generally recommended to set modest weight loss goals. The present study explores whether the amount of weight loss individuals strive for is associated with more positive psychological and behavioral outcomes. Hereto, 447 overweight and obese participants trying to lose weight completed two questionnaires with a 2-month interval. Many participants set goals that could be considered unrealistically high. However, higher weight loss goals did not predict dissatisfaction but predicted more effort in the weight loss attempt, as well as more self-reported short-term weight loss when baseline commitment and motivation were controlled for.

  7. Multi-phase ionization dynamics of carbon thin film irradiated by high power short pulse laser

    Science.gov (United States)

    Kawahito, Daiki; Kishimoto, Yasuaki

    2017-10-01

    The ionization dynamics of a carbon thin film irradiated by a high power short pulse laser in the range of 1019-20 W/cm2 are studied using the extended particle-based integrated code (EPIC), which includes atomic and collisional processes. Two types of ionization dynamics exhibiting different spatio-temporal structures are found to predominantly regulate the process, and arise depending on the laser amplitude. The first is a fast convective propagation for charge states up to C4+, which keeps a steep ionization front. The velocity of the front is of the order of the speed of light. The front formation results from the localized longitudinal electrostatic field and associated field ionization, which in turn propagates inside the film. This convective propagation is triggered when the laser field becomes high enough that electron bunches accelerated by the laser ponderomotive force reach relativistic energies and penetrate inside the film across the surface. The second dynamics is a fast non-diffusive propagation of ionization showing a long plasma density scale length for C5+ and C6+. This process results predominantly from electron impact ionization by high energy electron bunches successively produced by the laser. These electron bunches also excite wake fields that propagate inside the film and contribute to ionizing the film to higher charge states, i.e., C5+ and C6+, especially near the front surface. The effect of field ionization loss, which sensitively influences the ionization dynamics in the relatively low laser power regime, is also discussed.

  8. Enduring medial perforant path short-term synaptic depression at high pressure

    Directory of Open Access Journals (Sweden)

    Adolfo E Talpalar

    2010-10-01

    Full Text Available The high pressure neurological syndrome develops during deep diving (> 1.1 MPa involving impairment of cognitive functions, alteration of synaptic transmission and increased excitability in cortico-hippocampal areas. The medial perforant path (MPP, connecting entorhinal cortex with the hippocampal formation, displays synaptic frequency-dependent-depression (FDD under normal conditions. Synaptic FDD is essential for specific functions of various neuronal networks. We used rat cortico-hippocampal slices and computer simulations for studying the effects of pressure and its interaction with extracellular Ca2+ ([Ca2+]o on FDD at the MPP synapses. At atmospheric pressure, high [Ca2+]o (4-6 mM saturated single MPP field EPSP (fEPSP and increased FDD in response to short trains at 50 Hz. High pressure (HP; 10.1 MPa depressed single fEPSPs by 50 %. Increasing [Ca2+]o to 4 mM at HP saturated synaptic response at a subnormal level (only 20 % recovery of single fEPSPs, but generated a FDD similar to atmospheric pressure. Mathematical model analysis of the fractions of synaptic resources used by each fEPSP during trains (normalized to their maximum and the total fraction utilized within a train indicate that HP depresses synaptic activity also by reducing synaptic resources. This data suggest that MPP synapses may be modulated, in addition to depression of single events, by reduction of synaptic resources and then may have the ability to conserve their dynamic properties under different conditions.

  9. Crystalline-amorphous core-shell silicon nanowires for high capacity and high current battery electrodes.

    Science.gov (United States)

    Cui, Li-Feng; Ruffo, Riccardo; Chan, Candace K; Peng, Hailin; Cui, Yi

    2009-01-01

    Silicon is an attractive alloy-type anode material for lithium ion batteries because of its highest known capacity (4200 mAh/g). However silicon's large volume change upon lithium insertion and extraction, which causes pulverization and capacity fading, has limited its applications. Designing nanoscale hierarchical structures is a novel approach to address the issues associated with the large volume changes. In this letter, we introduce a core-shell design of silicon nanowires for highpower and long-life lithium battery electrodes. Silicon crystalline-amorphous core-shell nanowires were grown directly on stainless steel current collectors by a simple one-step synthesis. Amorphous Si shells instead of crystalline Si cores can be selected to be electrochemically active due to the difference of their lithiation potentials. Therefore, crystalline Si cores function as a stable mechanical support and an efficient electrical conducting pathway while amorphous shells store Li(+) ions. We demonstrate here that these core-shell nanowires have high charge storage capacity ( approximately 1000 mAh/g, 3 times of carbon) with approximately 90% capacity retention over 100 cycles. They also show excellent electrochemical performance at high rate charging and discharging (6.8 A/g, approximately 20 times of carbon at 1 h rate).

  10. Crystalline-Amorphous Core−Shell Silicon Nanowires for High Capacity and High Current Battery Electrodes

    KAUST Repository

    Cui, Li-Feng

    2009-01-14

    Silicon is an attractive alloy-type anode material for lithium ion batteries because of its highest known capacity (4200 mAh/g). However silicon\\'s large volume change upon lithium insertion and extraction, which causes pulverization and capacity fading, has limited its applications. Designing nanoscale hierarchical structures is a novel approach to address the issues associated with the large volume changes. In this letter, we introduce a core-shell design of silicon nanowires for highpower and long-life lithium battery electrodes. Silicon crystalline- amorphous core-shell nanowires were grown directly on stainless steel current collectors by a simple one-step synthesis. Amorphous Si shells instead of crystalline Si cores can be selected to be electrochemically active due to the difference of their lithiation potentials. Therefore, crystalline Si cores function as a stable mechanical support and an efficient electrical conducting pathway while amorphous shells store Li ions. We demonstrate here that these core-shell nanowires have high charge storage capacity (̃1000 mAh/g, 3 times of carbon) with ̃90% capacity retention over 100 cycles. They also show excellent electrochemical performance at high rate charging and discharging (6.8 A/g, ̃20 times of carbon at 1 h rate). © 2009 American Chemical Society.

  11. High-speed pulse train amplification in semiconductor optical amplifiers with optimized bias current

    OpenAIRE

    Xia, Mingjun; H. Ghafouri-Shiraz; Hou, Lianping; Kelly, Anthony E.

    2017-01-01

    In this paper, we have experimentally investigated the optimized bias current of semiconductor optical amplifiers (SOAs) to achieve high-speed input pulse train amplification with high gain and low distortion. Variations of the amplified output pulse duration with the amplifier bias currents have been analyzed and, compared to the input pulse duration, the amplified output pulse duration is broadened. As the SOA bias current decreases from the high level (larger than the saturated bias curren...

  12. Trigeminal high-frequency stimulation produces short- and long-term modification of reflex blink gain.

    Science.gov (United States)

    Ryan, Michael; Kaminer, Jaime; Enmore, Patricia; Evinger, Craig

    2014-02-01

    Reflex blinks provide a model system for investigating motor learning in normal and pathological states. We investigated whether high-frequency stimulation (HFS) of the supraorbital branch of the trigeminal nerve before the R2 blink component (HFS-B) decreases reflex blink gain in alert rats. As with humans (Mao JB, Evinger C. J Neurosci 21: RC151, 2001), HFS-B significantly reduced blink size in the first hour after treatment for rats. Repeated days of HFS-B treatment produced long-term depression of blink circuits. Blink gain decreased exponentially across days, indicating a long-term depression of blink circuits. Additionally, the HFS-B protocol became more effective at depressing blink amplitude across days of treatment. This depression was not habituation, because neither long- nor short-term blink changes occurred when HFS was presented after the R2. To investigate whether gain modifications produced by HFS-B involved cerebellar networks, we trained rats in a delay eyelid conditioning paradigm using HFS-B as the unconditioned stimulus and a tone as the conditioned stimulus. As HFS-B depresses blink circuits and delay conditioning enhances blink circuit activity, occlusion should occur if they share neural networks. Rats acquiring robust eyelid conditioning did not exhibit decreases in blink gain, whereas rats developing low levels of eyelid conditioning exhibited weak, short-term reductions in blink gain. These results suggested that delay eyelid conditioning and long-term HFS-B utilize some of the same cerebellar circuits. The ability of repeated HFS-B treatment to depress trigeminal blink circuit activity long term implied that it may be a useful protocol to reduce hyperexcitable blink circuits that underlie diseases like benign essential blepharospasm.

  13. High-speed highly temperature stable 980 nm VCSELs operating at 25 Gb/s at up to 85 °C for short reach optical interconnects

    Science.gov (United States)

    Mutig, Alex; Lott, James A.; Blokhin, Sergey A.; Moser, Philip; Wolf, Philip; Hofmann, Werner; Nadtochiy, Alexey M.; Bimberg, Dieter

    2011-03-01

    The progressive penetration of optical communication links into traditional copper interconnect markets greatly expands the applications of vertical cavity surface emitting lasers (VCSELs) for the next-generation of board-to-board, moduleto- module, chip-to-chip, and on-chip optical interconnects. Stability of the VCSEL parameters at high temperatures is indispensable for such applications, since these lasers typically reside directly on or near integrated circuit chips. Here we present 980 nm oxide-confined VCSELs operating error-free at bit rates up to 25 Gbit/s at temperatures as high as 85 °C without adjustment of the drive current and peak-to-peak modulation voltage. The driver design is therefore simplified and the power consumption of the driver electronics is lowered, reducing the production and operational costs. Small and large signal modulation experiments at various temperatures from 20 up to 85 °C for lasers with different oxide aperture diameters are presented in order to analyze the physical processes controlling the performance of the VCSELs. Temperature insensitive maximum -3 dB bandwidths of around 13-15 GHz for VCSELs with aperture diameters of 10 μm and corresponding parasitic cut-off frequencies exceeding 22 GHz are observed. Presented results demonstrate the suitability of our VCSELs for practical high speed and high temperature stable short-reach optical links.

  14. High Risk Posture on Motor-Manual Short Wood Logging System in Acacia mangium Plantation

    Directory of Open Access Journals (Sweden)

    Efi Yuliati Yovi

    2015-06-01

    Full Text Available Motor-manual logging has been considered as the most dominant logging system in Java Island, Indonesia. The system-which consisted of felling, delimbing, bucking, hauling, and transporting activities- involves a combination of stress factors e.q. difficult work postures, generation of force, and lifting techniques. In the other hand, combination of the three is well associated with high risk of work-related musculoskeletal injuries (MSIs, including musculoskeletal disorders. This research aimed to assess difficult work posture on felling, delimbing, bucking, and manually short wood hauling by employing rapid entire body assessment (REBA technique and muscular pain scoring based on the worker's perceive. It was revealed that felling and manual hauling were scored 4 in the REBA action level, indicated very high MSIs risk level, and categorized as “necessary now” for an injury risk preventive action. The workers' pain scoring indicated that low back (spine in general disorders resulting in low back pain has been considered to be the one of the leading safety issues in the felling and manual hauling. Regardless to complex mechanism of how the personal risk and environmental factors associated with manual material handling injuries, job-related factors approach should be underlined in the MSIs prevention initiative in motor-manual logging. Keywords: motor-manual logging, difficult work posture, REBA, MSIs, low back pain

  15. Future of high-speed short-reach interconnects using clad-dielectric waveguide

    Science.gov (United States)

    Lee, J. Y.; Song, H. I.; Kwon, S. W.; Bae, H. M.

    2017-02-01

    The ever-increasing demand for bandwidth requires advanced interconnect solutions satisfying functional and economic constraints. A new interconnect called electrical tube (E-TUBE) is proposed as a cost-and-power-effective all-electricaldomain wideband waveguide solution for high-speed, high-volume, and short-reach communication links. Unlike conventional optical solutions, the E-TUBE achieves state-of-the-art performance in terms of bandwidth-per-carrier frequency, power, and density without any precision manufacturing process. The E-TUBE exhibits a frequencyindependent loss-profile and has 20GHz bandwidth over the V band. The inherent frequency response of the E-TUBE enables a single-sideband signal transmission and renders double data throughput without any physical overhead. Transmission up to 14Gb/s signals over 1.2m has been tested using 73GHz carrier frequency (fC). The IC is fabricated in 40nm CMOS and the figure-of-merit of the interface is 0.52J/b/m×*fC (Radio frequency circuits only: 0.3J/b/m×*fC).

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-08-29

    A high-voltage direct-current (HVDC) transmission system includes an alternating current (AC) electrical source and a power converter channel that includes an AC-DC converter electrically coupled to the electrical source and a DC-AC inverter electrically coupled to the AC-DC converter. The AC-DC converter and the DC-AC inverter each include a plurality of legs that includes at least one switching device. The power converter channel further includes a commutating circuit communicatively coupled to one or more switching devices. The commutating circuit is configured to "switch on" one of the switching devices during a first portion of a cycle of the H-bridge switching circuits and "switch off" the switching device during a second portion of the cycle of the first and second H-bridge switching circuits.

  17. The Applications of Current Comparators in the Measurements on High Voltage Insulation

    Directory of Open Access Journals (Sweden)

    Fei Yi-jun

    2016-01-01

    Full Text Available This paper describes the basic structure of the current comparator used for high voltage insulation measurements. Further applications for the current comparator in high voltage insulation are investigated and developed. A measuring system for the measurement of harmonics in the loss current of water tree aged insulation is described, as well as the principles to measure partial discharges with the current comparator bridge. A new system for the measurement of the DC component in the leakage current of insulation is de1veloped and presented. The results of experiments on XLPE cable insulation are also given.

  18. Study on High Current PWM Unipolar Four Phases Driver for Stepper Motor Control

    Directory of Open Access Journals (Sweden)

    Alexandru Morar

    2013-06-01

    Full Text Available This paper presents the study on highcurrent PWM, unipolar stepper motor controller/driver, are remarkable for simplicity, high – reliability, multifunctional facilities for four phases hybrid stepper motor.

  19. Analytical model for subthreshold current and subthreshold swing of short-channel double-material-gate MOSFETs with strained-silicon channel on silicon—germanium substrates

    Science.gov (United States)

    Tiwari, Pramod Kumar; Krishna Saramekala, Gopi; Dubey, Sarvesh; Mukhopadhyay, Anand Kumar

    2014-10-01

    The present work gives some insight into the subthreshold behaviour of short-channel double-material-gate strained-silicon on silicon—germanium MOSFETs in terms of subthreshold swing and off-current. The formulation of subthreshold current and, thereupon, the subthreshold swing have been done by exploiting the expression of potential distribution in the channel region of the device. The dependence of the subthreshold characteristics on the device parameters, such as Ge mole fraction, gate length ratio, work function of control gate metal and gate length, has been tested in detail. The analytical models have been validated by the numerical simulation results that were obtained from the device simulation software ATLAS™ by Silvaco Inc.

  20. Plant Growth under Natural Light Conditions Provides Highly Flexible Short-Term Acclimation Properties toward High Light Stress

    Science.gov (United States)

    Schumann, Tobias; Paul, Suman; Melzer, Michael; Dörmann, Peter; Jahns, Peter

    2017-01-01

    Efficient acclimation to different growth light intensities is essential for plant fitness. So far, most studies on light acclimation have been conducted with plants grown under different constant light regimes, but more recent work indicated that acclimation to fluctuating light or field conditions may result in different physiological properties of plants. Thale cress (Arabidopsis thaliana) was grown under three different constant light intensities (LL: 25 μmol photons m−2 s−1; NL: 100 μmol photons m−2 s−1; HL: 500 μmol photons m−2 s−1) and under natural fluctuating light (NatL) conditions. We performed a thorough characterization of the morphological, physiological, and biochemical properties focusing on photo-protective mechanisms. Our analyses corroborated the known properties of LL, NL, and HL plants. NatL plants, however, were found to combine characteristics of both LL and HL grown plants, leading to efficient and unique light utilization capacities. Strikingly, the high energy dissipation capacity of NatL plants correlated with increased dynamics of thylakoid membrane reorganization upon short-term acclimation to excess light. We conclude that the thylakoid membrane organization and particularly the light-dependent and reversible unstacking of grana membranes likely represent key factors that provide the basis for the high acclimation capacity of NatL grown plants to rapidly changing light intensities. PMID:28515734

  1. Short pulse, high resolution, backlighters for point projection high-energy radiography at the National Ignition Facility

    Science.gov (United States)

    Tommasini, R.; Bailey, C.; Bradley, D. K.; Bowers, M.; Chen, H.; Di Nicola, J. M.; Di Nicola, P.; Gururangan, G.; Hall, G. N.; Hardy, C. M.; Hargrove, D.; Hermann, M.; Hohenberger, M.; Holder, J. P.; Hsing, W.; Izumi, N.; Kalantar, D.; Khan, S.; Kroll, J.; Landen, O. L.; Lawson, J.; Martinez, D.; Masters, N.; Nafziger, J. R.; Nagel, S. R.; Nikroo, A.; Okui, J.; Palmer, D.; Sigurdsson, R.; Vonhof, S.; Wallace, R. J.; Zobrist, T.

    2017-05-01

    High-resolution, high-energy X-ray backlighters are very active area of research for radiography experiments at the National Ignition Facility (NIF) [Miller et al., Nucl. Fusion 44, S228 (2004)], in particular those aiming at obtaining Compton-scattering produced radiographs from the cold, dense fuel surrounding the hot spot. We report on experiments to generate and characterize point-projection-geometry backlighters using short pulses from the advanced radiographic capability (ARC) [Crane et al., J. Phys. 244, 032003 (2010); Di Nicola et al., Proc. SPIE 2015, 93450I-12], at the NIF, focused on Au micro-wires. We show the first hard X-ray radiographs, at photon energies exceeding 60 keV, of static objects obtained with 30 ps-long ARC laser pulses, and the measurements of strength of the X-ray emission, the pulse duration and the source size of the Au micro-wire backlighters. For the latter, a novel technique has been developed and successfully applied.

  2. High-energy emission in short GRBs and the role of magnetar central engines

    NARCIS (Netherlands)

    Rowlinson, A.; O'Brien, P.T.

    2013-01-01

    A significant number of long Gamma-ray Bursts (GRBs) detected by the Swift Satellite have a plateau phase signifying ongoing energy injection. Using BAT and XRT observations, we find that many short GRBs show similar behavior which challenges the typical short GRB progenitor model. We suggest the

  3. Current Sharing inside a High Power IGBT Module at the Negative Temperature Coefficient Operating Region

    CERN Document Server

    AUTHOR|(CDS)2084596; Papastergiou, Konstantinos; Bongiorno, M; Thiringer, T

    2016-01-01

    This work investigates the current sharing effect of a high power Soft Punch Through IGBT module in the Negative Temperature Coefficient region. The unbalanced current sharing between two of the substrates is demonstrated for different current and temperature levels and its impact on the thermal stressing of the device is evaluated. The results indicate that the current asymmetry does not lead to a significant thermal stressing unbalance between the substrates.

  4. Derivation of Parabolic Current Control with High Precision, Fast Convergence and Extended Voltage Control Application

    OpenAIRE

    Zhang, Lanhua

    2016-01-01

    Current control is an important topic in modern power electronics system. For voltage source inverters, current control loop ensures the waveform quality at steady state and the fast response at transient state. To improve the current control performance, quite a few nonlinear control strategies have been presented and one well-known strategy is the hysteresis current control. It achieves fast response without stability issue and it has high control precision. However, for voltage source inve...

  5. High-temperature solar receiver integrated with a short-term storage system

    Science.gov (United States)

    Giovannelli, Ambra; Bashir, Muhammad Anser; Archilei, Erika Maria

    2017-06-01

    Small-Scale Concentrated Solar Power Plants could have a potential market for off-grid applications in rural contexts with limited access to the electrical grid and favorable environmental characteristics. Some Small-Scale plants have already been developed, like the 25-30 kWe Dish-Stirling engine. Other ones are under development as, for example, plants based on Parabolic Trough Collectors coupled with Organic Rankine Cycles. Furthermore, the technological progress achieved in the development of new small high-temperature solar receiver, makes possible the development of interesting systems based on Micro Gas Turbines coupled with Dish collectors. Such systems could have several advantages in terms of costs, reliability and availability if compared with Dish-Stirling plants. In addition, Dish-Micro Gas Turbine systems are expected to have higher performance than Solar Organic Rankine Cycle plants. The present work focuses the attention on some challenging aspects related to the design of small high-temperature solar receivers for Dish-Micro Gas Turbine systems. Natural fluctuations in the solar radiation can reduce system performance and damage seriously the Micro Gas Turbine. To stabilize the system operation, the solar receiver has to assure a proper thermal inertia. Therefore, a solar receiver integrated with a short-term storage system based on high-temperature phase-change materials is proposed in this paper. Steady-state and transient analyses (for thermal storage charge and discharge phases) have been carried out using the commercial CFD code Ansys-Fluent. Results are presented and discussed.

  6. Advances in high repetition rate, ultra-short, gigawatt laser systems for time-resolved spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    DiMauro, L.F.

    1991-12-31

    The objective of this article is to emphasize the current advances in the development of high-repetition rate amplifier pumps. Although this review highlights amplifier pump development, any recent data from achieved outputs via the tunable amplifier section is also discussed. The first section describes desirable parameters attributable to the pump amplifier while the rest of the article deals with specific examples for various options. The pump amplifiers can be characterized into two distinct classes; those achieving operation in the hundred hertz regime and those performing at repetition rates {ge}1kHz. 23 refs., 4 figs.

  7. Advances in high repetition rate, ultra-short, gigawatt laser systems for time-resolved spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    DiMauro, L.F.

    1991-01-01

    The objective of this article is to emphasize the current advances in the development of high-repetition rate amplifier pumps. Although this review highlights amplifier pump development, any recent data from achieved outputs via the tunable amplifier section is also discussed. The first section describes desirable parameters attributable to the pump amplifier while the rest of the article deals with specific examples for various options. The pump amplifiers can be characterized into two distinct classes; those achieving operation in the hundred hertz regime and those performing at repetition rates {ge}1kHz. 23 refs., 4 figs.

  8. The added value of stochastic spatial disaggregation for short-term rainfall forecasts currently available in Canada

    Science.gov (United States)

    Gagnon, Patrick; Rousseau, Alain N.; Charron, Dominique; Fortin, Vincent; Audet, René

    2017-11-01

    Several businesses and industries rely on rainfall forecasts to support their day-to-day operations. To deal with the uncertainty associated with rainfall forecast, some meteorological organisations have developed products, such as ensemble forecasts. However, due to the intensive computational requirements of ensemble forecasts, the spatial resolution remains coarse. For example, Environment and Climate Change Canada's (ECCC) Global Ensemble Prediction System (GEPS) data is freely available on a 1-degree grid (about 100 km), while those of the so-called High Resolution Deterministic Prediction System (HRDPS) are available on a 2.5-km grid (about 40 times finer). Potential users are then left with the option of using either a high-resolution rainfall forecast without uncertainty estimation and/or an ensemble with a spectrum of plausible rainfall values, but at a coarser spatial scale. The objective of this study was to evaluate the added value of coupling the Gibbs Sampling Disaggregation Model (GSDM) with ECCC products to provide accurate, precise and consistent rainfall estimates at a fine spatial resolution (10-km) within a forecast framework (6-h). For 30, 6-h, rainfall events occurring within a 40,000-km2 area (Québec, Canada), results show that, using 100-km aggregated reference rainfall depths as input, statistics of the rainfall fields generated by GSDM were close to those of the 10-km reference field. However, in forecast mode, GSDM outcomes inherit of the ECCC forecast biases, resulting in a poor performance when GEPS data were used as input, mainly due to the inherent rainfall depth distribution of the latter product. Better performance was achieved when the Regional Deterministic Prediction System (RDPS), available on a 10-km grid and aggregated at 100-km, was used as input to GSDM. Nevertheless, most of the analyzed ensemble forecasts were weakly consistent. Some areas of improvement are identified herein.

  9. Effect of high-temperature/current stress on the forward tunneling current of InGaN/GaN high-power blue-light-emitting diodes

    Science.gov (United States)

    Liu, Sheng; Zheng, Chenju; Lv, Jiajiang; Liu, Mengling; Zhou, Shengjun

    2017-08-01

    Through the analysis of the temperature-dependent current-voltage (I-V) characteristics of the fabricated InGaN/GaN high-power blue-light-emitting diodes (LEDs), the low-bias region was confirmed to be dominated by tunneling current, while the medium-bias region was dominated by diffusion-recombination current. Electrons and heavy holes appeared to play similar roles in the tunneling current of the fabricated LEDs, with no apparent dominant tunneling entity determined by characteristic energy as previous works suggested. After 1000 h of high-temperature/current stress, the medium-bias regions of the I-V curves of LEDs remained almost unchanged, while the current in the low-bias region was greatly enhanced by the stress, which confirmed the different carrier transport mechanism behaviors in the low- and medium-bias regions. Further comparison between the I-V characteristics of the unstressed and stressed LEDs suggested that the change in I-V curve was associated with the increase in defect density and the apparent doping concentration in the InGaN/GaN multiple-quantum-well (MQW) active region.

  10. A Psychometric Evaluation of the Career Decision Self-Efficacy Scale-Short Form in Chinese High School Students

    Science.gov (United States)

    Hampton, Nan Zhang

    2006-01-01

    This study explores the reliability and validity of the Career Decision Self-Efficacy Scale-Short Form (CDSES-SF) in Chinese high school students. One hundred and eighty-three high school students from a city in northeastern China participated in the study. The results indicate that scores on the CDSES-SF are reliable (internal consistency…

  11. Micro- and nanostructure of a titanium surface electric-spark-doped with tantalum and modified by high-frequency currents

    Science.gov (United States)

    Fomin, A. A.; Fomina, M. A.; Koshuro, V. A.; Rodionov, I. V.; Voiko, A. V.; Zakharevich, A. M.; Aman, A.; Oseev, A.; Hirsch, S.; Majcherek, S.

    2016-09-01

    We have studied the characteristics of the porous microstructure of tantalum coatings obtained by means of electric spark spraying on the surface of commercial grade titanium. It is established that, at an electric spark current within 0.8-2.2 A, a mechanically strong tantalum coating microstructure is formed with an average protrusion size of 5.1-5.4 µm and pore sizes from 3.5 to 9.2 µm. On the nanoscale, a structurally heterogeneous state of coatings has been achieved by subsequent thermal modification at 800-830°C with the aid of high-frequency currents. A metal oxide nanostructure with grain sizes from 40 to 120 nm is formed by short-time (~30 s) thermal modification. The coating hardness reaches 9.5-10.5 GPa at an elastic modulus of 400-550 GPa.

  12. Optimization of Silicon MZM Fabrication Parameters for High Speed Short Reach Interconnects at 1310 nm

    Directory of Open Access Journals (Sweden)

    Alexis Abraham

    2016-11-01

    Full Text Available Optical modulators are key components to realize photonic circuits, and Mach-Zehnder modulators (MZM are often used for high speed short reach interconnects. In order to maximize the tolerable path loss of a transmission link at a given bitrate, the MZM needs to be optimized. However, the optimization can be complex since the overall link performance depends on various parameters, and, for the MZM in particular, implies several trade-offs between efficiency, losses, and bandwidth. In this work, we propose a general and rigorous method to optimize silicon MZM. We first describe the optical link, and the numerical method used for this study. Then we present the results associated to the active region for 1310 nm applications. An analytical model is generated, and allows us to quickly optimize the p-n junction depending of the targeted performances for the MZM. Taking into account the required optical link parameters, the maximum tolerable path losses for different length of MZM is determined. By applying this method, simulations show that the optimum MZM length for 25 Gbps applications is 4 mm with an efficiency of 1.87 V·cm, 0.52 dB/mm of losses. A tolerable path loss of more than 25 dB is obtained.

  13. Neural adaptations after short-term wingate-based high-intensity interval training

    Science.gov (United States)

    Vera-Ibañez, Antonio; Colomer-Poveda, David; Romero-Arenas, Salvador; Viñuela-García, Manuel; Márquez, Gonzalo

    2017-01-01

    Objectives: This study examined the neural adaptations associated with a low-volume Wingate-based High Intensity Interval Training (HIIT). Methods: Fourteen recreationally trained males were divided into an experimental (HIIT) and a control group to determine whether a short-term (4 weeks) Wingate-based HIIT program could alter the Hoffmann (H-) reflex, volitional (V-) wave and maximum voluntary contraction (MVC) of the plantar-flexor muscles, and the peak power achieved during a Wingate test. Results: Absolute and relative peak power increased in the HIIT group (ABS_Ppeak: +14.7%, P=0.001; and REL_Ppeak: +15.0%, P=0.001), but not in the control group (ABS_Ppeak: P=0.466; and REL_Ppeak: P=0.493). However, no significant changes were found in the MVC (P>0.05 for both groups). There was a significant increase in H-reflex size after HIIT (+24.5%, P=0.004), while it remained unchanged in the control group (P=0.134). No significant changes were observed either in the V-wave or in the Vwave/Mwave ratio (P>0.05 for both groups). Conclusion: The Wingate-based training led to an increased peak power together with a higher spinal excitability. However, no changes were found either in the volitional wave or in the MVC, indicating a lack of adaptation in the central motor drive. PMID:29199186

  14. Influence of Random Inclusion of Coconut Fibres on the Short term Strength of Highly Compressible Clay

    Science.gov (United States)

    Ramani Sujatha, Evangelin; SaiSree, S.; Prabalini, C.; Aysha Farsana, Z.

    2017-07-01

    The choice of natural fibres for soil stabilization provides an economic, safe and eco-friendly alternative to improve the properties of soil. They are an important step forward toward sustainable development. An attempt was made to study the influence of the random addition of untreated coconut fibres on the short term strength of soil, its stress-strain behavior, compaction characteristics and index properties. The soil selected for the study is a highly compressible clay sample with a liquid limit of 52.5 % and plasticity index of 38 %. The soil has no organic content. The study reveals that the compaction curves tend to shift to the right side, indicating more plastic behavior with the addition of fibres. The addition of fibres also reorient the soil structure to a more dispersed fashion. A significant increase in the unconfined compressive strength is also observed. An increase of nearly 51 % in the unconfined compressive strength is observed at 0.75 % coir inclusion. The stress-strain behavior of the soil shows a shift toward more plastic behavior. The mode of failure of the soil specimen is by cracking and with fibre inclusion, length of the failure cracks is restrained as the fibre tends to hold the cracks together, resulting in shorter cracks, with significant bulging of the specimen at failure.

  15. Temperature measurement by IR camera of heated device to high temperature during a short time

    Science.gov (United States)

    Sonneck-Museux, Nathanaëlle; Vergé, Philippe; Judic, Jean-Pierre; Edard, Pierrick

    2015-04-01

    A device allowing heating a liquid to high temperatures during a very short time has been conceived in our laboratory. The goal of this survey is to find the suitable experimental configurations, so that tested material affected by the temperatures coved between 200 and 750°C. This study is achieved to the Solar Furnace of the DGA in Odeillo. The cavity containing the liquid is a thermocouple sleeve (capillary) in Inconel 600. Its extremity is closed tightly by a removable steel plug permitting the tightness after replenishment. An electromagnet associated to a generator of delay permit to make fall the whole after the solar irradiation in liquid nitrogen in order to stop the reaction of "deterioration" of the tested product. According to capillary dimensions and to heating time, the temperature measurement using a pyrometer is not possible. A second possibility is using thermocouple, but it is not easy to join this captor on Inconel 600. Using by infrared camera allows observing the presence or the absence of inflammation during the solar irradiation and the sleeve fall too. The measures of temperatures by thermocouple show a lot of variability. The measures comparison with those by infrared camera shows a phenomenon of "heat well". Several score of tests to the solar furnace have been achieved in different experimental configurations. Nine experimental configurations have been validated, for variable flux of 100 to 500W/cm². The observation by infrared camera permitted to validate the conceived system and to verify the homogeneity of the sleeve heated.

  16. High serum YKL-40 level after surgery for colorectal carcinoma is related to short survival

    DEFF Research Database (Denmark)

    Cintin, Christina; Johansen, Julia S; Christensen, Ib Jarle

    2002-01-01

    carcinoma are associated with a significantly poorer prognosis compared to patients with normal serum YKL-40. In the current study the authors evaluated the value of serum YKL-40 in monitoring patients with colorectal carcinoma. METHODS: YKL-40 was determined by an in-house radioimmunoassay method in serum...... died. RESULTS: Serum YKL-40 was significantly decreased in the first postoperative blood sample in 62% of patients with high preoperative levels. In addition, patients with high serum YKL-40 (adjusted for age) six months after curative operation had significantly shorter survival times (P = 0...... that patients exhibiting elevated serum YKL-40 had an increased hazard for death within the following six months compared to those patients with normal serum YKL-40 level (hazard ratio [HR] = 9.6, 95% confidence interval [CI]: 6.0-15.5, P

  17. Short- and long-term health consequences and current satisfaction levels for altruistic anonymous, identity-release and known oocyte donors.

    Science.gov (United States)

    Söderström-Anttila, Viveca; Miettinen, Anneli; Rotkirch, Anna; Nuojua-Huttunen, Sinikka; Poranen, Anna-Kaisa; Sälevaara, Mari; Suikkari, Anne-Maria

    2016-03-01

    What are the short- and long-term health consequences and current satisfaction of altruistic oocyte donors? Donating oocytes in the majority (>90%) of donation cycles is not associated with harmful long-term general or reproductive health effects. Knowledge of long-term health effects of oocyte donation on donors is sparse and follow-up studies have usually been carried out on commercial donors. Thus far, no major long-term harmful effects have been demonstrated. Most studies have reported a high level of donor satisfaction, but also less favorable experiences have been published. A retrospective cross-sectional survey of all women who had donated oocytes between 1990 and 2012 at three fertility clinics was carried out in spring 2013. A self-administered questionnaire was sent out to a total of 569 former oocyte donors. In all, 428 past donors answered the questionnaire assessing donor's demographic characteristics, short- and long-term medical and psychological experiences and satisfaction related to donations. Of the donors, 87% (371/428) were unknown and 13% (57/428) were known to the recipient. The mean follow-up time after the donation was 11.2 years (range from 0.5 to 23 years) and the mean age of the respondents was 42 years at the time of the study. To learn whether the demographic profile of donors was affected by the Finnish Assisted Reproduction Technology (ART) Act of 2007, we divided the 428 respondents into two groups: (i) women whose first donation took place between 1990 and 2007 (79% of the respondents) and (ii) women whose first donation took place between 2008 and 2012 (21% of the respondents). Before 2008, donors were non-identifiable (anonymous) but after 2008 persons born as a result of gamete donation could, from the age of 18, receive on request information identifying the donor. The response rate was 75% (428/569). The mean age of the donors did not differ between the two time periods, but there was a higher proportion of donors in the

  18. 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}.

  19. Short-term assessment of BCR repertoires of SLE patients after high dose glucocorticoid therapy with high-throughput sequencing.

    Science.gov (United States)

    Shi, Bin; Yu, Jiang; Ma, Long; Ma, Qingqing; Liu, Chunmei; Sun, Suhong; Ma, Rui; Yao, Xinsheng

    2016-01-01

    We analyze and assess BCR repertoires of SLE patients before and after high dose glucocorticoid therapy to address two fundamental questions: (1) After the treatment, how the BCR repertoire of SLE patient change on the clone level? (2) How to screen putative autoantibody clone set from BCR repertoire of SLE patients? The PBMCs of two SLE patients (P1 and P2) at different time points were collected, and DNA of these samples were extracted. High-throughput sequencing technology was applied in detection of BCR repertoire. Finally, we used bioinformatic methodology to analyse sequence data. We found that these two patients lost some IGHV3 family genes usage after treatment compared with before treatment. For pairing of IGHV-IGHJ gene, no significant change was shown for each patient. In addition, analyses of the composition of H-CDR3 showed overall AA compositions of H-CDR3 at three time points in each SLE patients were very similar, and the results of H-CDR3 AA usage that had the same length (14 AA) and the same position were similar. Antinuclear antibody tests of SLE patients showed that level of some antinuclear antibodies reduced after treatment; however, there was no sign that the percentage of autoantibody clones in BCR repertoires would reduce. High dose glucocorticoid treatment in short term will have little impact on composition of BCR repertoire of SLE patient. Treatment can reduce the amount of autoantibody in the protein level, but may not reduce the percentage of autoantibody clones in BCR repertoire in the clonal level.

  20. Autonomic Function Predicts Fitness Response to Short-Term High-Intensity Interval Training.

    Science.gov (United States)

    Kiviniemi, A M; Tulppo, M P; Eskelinen, J J; Savolainen, A M; Kapanen, J; Heinonen, I H A; Hautala, A J; Hannukainen, J C; Kalliokoski, K K

    2015-11-01

    We tested the hypothesis that baseline cardiac autonomic function and its acute response to all-out interval exercise explains individual fitness responses to high-intensity interval training (HIT). Healthy middle-aged sedentary men performed HIT (n=12, 4-6×30 s of all-out cycling efforts with 4-min recovery) or aerobic training (AET, n=9, 40-60 min at 60% of peak workload in exercise test [Loadpeak]), comprising 6 sessions within 2 weeks. Low (LF) and high frequency (HF) power of R-R interval oscillation were analyzed from data recorded at supine and standing position (5+5 min) every morning during the intervention. A significant training effect (ptraining*group interaction, was observed in Loadpeak and peak oxygen consumption (VO2peak). Pre-training supine LF/HF ratio, an estimate of sympathovagal balance, correlated with training outcome in Loadpeak (Spearman's rho [rs]=-0.74, p=0.006) and VO2peak (rs=- 0.59, p=0.042) in the HIT but not the AET group. Also, the mean change in the standing LF/HF ratio in the morning after an acute HIT exercise during the 1(st) week of intervention correlated with training response in Loadpeak (rs=- 0.68, p=0.014) and VO2peak (rs=-0.60, p=0.039) with HIT but not with AET. In conclusion, pre-training cardiac sympathovagal balance and its initial alterations in response to acute HIT exercise were related to fitness responses to short-term HIT. © Georg Thieme Verlag KG Stuttgart · New York.

  1. High-speed pulse train amplification in semiconductor optical amplifiers with optimized bias current.

    Science.gov (United States)

    Xia, Mingjun; Ghafouri-Shiraz, H; Hou, Lianping; Kelly, Anthony E

    2017-02-01

    In this paper, we have experimentally investigated the optimized bias current of semiconductor optical amplifiers (SOAs) to achieve high-speed input pulse train amplification with high gain and low distortion. Variations of the amplified output pulse duration with the amplifier bias currents have been analyzed and, compared to the input pulse duration, the amplified output pulse duration is broadened. As the SOA bias current decreases from the high level (larger than the saturated bias current) to the low level, the broadened pulse duration of the amplified output pulse initially decreases slowly and then rapidly. Based on the analysis, an optimized bias current of SOA for high-speed pulse train amplification is introduced. The relation between the SOA optimized bias current and the parameters of the input pulse train (pulse duration, power, and repetition rate) are experimentally studied. It is found that the larger the input pulse duration, the lower the input pulse power or a higher repetition rate can lead to a larger SOA optimized bias current, which corresponds to a larger optimized SOA gain. The effects of assist light injection and different amplifier temperatures on the SOA optimized bias current are studied and it is found that assist light injection can effectively increase the SOA optimized bias current while SOA has a lower optimized bias current at the temperature 20°C than that at other temperatures.

  2. Quantifying the erosion effect on current carbon budget of European agricultural soils at high spatial resolution.

    Science.gov (United States)

    Lugato, Emanuele; Paustian, Keith; Panagos, Panos; Jones, Arwyn; Borrelli, Pasquale

    2016-05-01

    The idea of offsetting anthropogenic CO2 emissions by increasing global soil organic carbon (SOC), as recently proposed by French authorities ahead of COP21 in the 'four per mil' initiative, is notable. However, a high uncertainty still exits on land C balance components. In particular, the role of erosion in the global C cycle is not totally disentangled, leading to disagreement whether this process induces lands to be a source or sink of CO2. To investigate this issue, we coupled soil erosion into a biogeochemistry model, running at 1 km(2) resolution across the agricultural soils of the European Union (EU). Based on data-driven assumptions, the simulation took into account also soil deposition within grid cells and the potential C export to riverine systems, in a way to be conservative in a mass balance. We estimated that 143 of 187 Mha have C erosion rates 0.45 Mg C ha(-1) yr(-1). In comparison with a baseline without erosion, the model suggested an erosion-induced sink of atmospheric C consistent with previous empirical-based studies. Integrating all C fluxes for the EU agricultural soils, we estimated a net C loss or gain of -2.28 and +0.79 Tg yr(-1) of CO2 eq, respectively, depending on the value for the short-term enhancement of soil C mineralization due to soil disruption and displacement/transport with erosion. We concluded that erosion fluxes were in the same order of current carbon gains from improved management. Even if erosion could potentially induce a sink for atmospheric CO2, strong agricultural policies are needed to prevent or reduce soil erosion, in order to maintain soil health and productivity. © 2015 The Authors. Global Change Biology Published by John Wiley & Sons Ltd.

  3. Presal36: a high resolution ocean current model for Brazilian pre-salt area: implementation and validation results

    Energy Technology Data Exchange (ETDEWEB)

    Schoellkopf, Jacques P. [Advanced Subsea do Brasil Ltda., Rio de Janeiro, RJ (Brazil)

    2012-07-01

    The PRESAL 36 JIP is a project for the development of a powerful Ocean Current Model of 1/36 of a degree resolution, nested in an existing Global Ocean global Model, Mercator PSY4 (1/12-a-degree resolution ), with tide corrections, improved bathymetry accuracy and high frequency atmospheric forcing (every 3 hours). The simulation outputs will be the 3 dimensional structure of the velocity fields (u,v,w) at 50 vertical levels over the water column, including geostrophic, Ekman and tidal currents, together with Temperature, Salinity and sea surface height at a sub-mesoscale spatial resolution. Simulations will run in hindcast, nowcast and forecast modes, with a temporal resolution of 3 hours . This Ocean current model will allow to perform detailed statistical studies on various areas using conditions analysed using hindcast mode, short term operational condition prediction for various surface and sub sea operations using realtime and Forecast modes. The paper presents a publication of significant results of the project, in term of pre-sal zoomed model implementation, and high resolution model validation. It demonstrate the capability to properly describe ocean current phenomenon at beyond mesoscale frontier. This project demonstrate the feasibility of obtaining accurate information for engineering studies and operational conditions, based on a 'zoom technique' starting from global ocean models. (author)

  4. Improved high-force magnetic tweezers for stretching and refolding of proteins and short DNA.

    Science.gov (United States)

    Chen, Hu; Fu, Hongxia; Zhu, Xiaoying; Cong, Peiwen; Nakamura, Fumihiko; Yan, Jie

    2011-01-19

    Although magnetic tweezers have many unique advantages in terms of specificity, throughput, and force stability, this tool has had limited application on short tethers because accurate measurement of force has been difficult for short tethers under large tension. Here, we report a method that allows us to apply magnetic tweezers to stretch short biomolecules with accurate force calibration over a wide range of up to 100 pN. We demonstrate the use of the method by overstretching of a short DNA and unfolding/refolding a protein of filamin A immunoglobulin domains 1-8. Other potential applications of this method are also discussed. Copyright © 2011 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  5. Current state and prospects of carbon management in high latitudes of Northern Eurasia

    Science.gov (United States)

    Schepaschenko, Dmitry; Shvidenko, Anatoly

    2010-05-01

    The current state and trajectories of future development of natural landscapes in high latitudes of Northern Eurasia are defined inter alia by (1) current unsatisfactory social and economic situation in boreal Northern Eurasia; (2) the dramatic magnitude of on-going and expected climatic change (warming up to 10-12oC under global warming at 4oC); (3) increasing anthropogenic pressure, particularly in regions of intensive oil and gas exploration and extraction; (4) large areas of sparsely populated and practically unmanaged land; (5) vulnerability of northern ecosystems which historically developed under cold climates and buffering capacity of which is not well known; (6) risk of catastrophic natural disturbances (fire, insect outbreaks) whose frequency and severity have accelerated during recent decades; and (7) high probability of irreversible changes of vegetation cover. These specifics are overlapped with insufficient governance of natural renewable resources (e.g., forests) and destructed practice of industrial development of new territories (oil and gas extraction and exploration, metallurgy etc.). Based on a full carbon account for terrestrial vegetation ecosystems of Northern Eurasia, we analyze the relative impacts of major drivers on magnitude and uncertainty of the Net Ecosystem Carbon Balance (NECB) under current and expected climate and environment. Dynamic trends and interannual variability of NECB are mostly dependent on weather conditions during growth seasons of individual years, regimes of natural disturbances, and anthropogenic impacts on ecosystems. In a short term, disturbances and human impacts cause a theoretically 'manageable' part of the full carbon account, which on average is estimated to be of about 20% of annual net primary production. In a long term, thawing of permafrost and change of hydrological regimes of vast territories may result in a catastrophic decline of the forested area and wide distribution of 'green desertification'. The

  6. INFLUENCE OF RAMADAN FASTING ON ANAEROBIC PERFORMANCE AND RECOVERY FOLLOWING SHORT TIME HIGH INTENSITY EXERCISE

    Directory of Open Access Journals (Sweden)

    Umid Karli

    2007-12-01

    Full Text Available The aim of this study was to investigate the effects of Ramadan fasting on anaerobic power and capacity and the removal rate of lactate after short time high intensity exercise in power athletes. Ten male elite power athletes (2 wrestlers, 7 sprinters and 1 thrower, aged 20-24 yr, mean age 22.30 ± 1.25 yr participated in this study. The subjects were tested three times [3 days before the beginning of Ramadan (Pre-RF, the last 3 days of Ramadan (End-RF and the last 3 days of the 4th week after the end of Ramadan (After-RF]. Anaerobic power and capacity were measured by using the Wingate Anaerobic Test (WAnT at Pre-RF, End-RF and After- RF. Capillary blood samples for lactate analyses and heart rate recordings were taken at rest, immediately after WAnT and throughout the recovery period. Repeated measures of ANOVA indicated that there were no significant changes in body weight, body mass index, fat free mass, percentage of body fat, daily sleeping time and daily caloric intake associated with Ramadan fasting. No significant changes were found in total body water either, but urinary density measured at End-RF was significantly higher than After-RF. Similarity among peak HR and peak LA values at Pre-RF, End- RF and After-RF demonstrated that cardiovascular and metabolic stress caused by WAnT was not affected by Ramadan fasting. In addition, no influence of Ramadan fasting on anaerobic power and capacity and removal rate of LA from blood following high intensity exercise was observed. The results of this study revealed that if strength-power training is performed regularly and daily food intake, body fluid balance and daily sleeping time are maintained as before Ramadan, Ramadan fasting will not have adverse effects on body composition, anaerobic power and capacity, and LA metabolism during and after high intensity exercise in power athletes

  7. A short term high-fat high-sucrose diet in mice impairs optic nerve recovery after injury and this is not reversed by exercise.

    Science.gov (United States)

    Chrysostomou, Vicki; van Wijngaarden, Peter; Steinberg, Gregory R; Crowston, Jonathan G

    2017-09-01

    The aim of the current work was to test whether increased intake of dietary fat and sucrose in mice modifies the response of retinal ganglion cells (RGCs) of the optic nerve to injury, and whether any effects of diet are influenced by physical activity levels. C57BL/6J mice were given a high-fat high-sucrose (HFS) diet for 7 weeks, with or without exposure to regular exercise by swimming (60 min/day, 5 days/week). Injury to RGCs was subsequently induced by acute elevation of intraocular pressure (IOP) and retinas were assessed for function and structure. We report that mice on a HFS diet had similar body mass and blood glucose levels compared to mice on a control diet but suffered a 30% greater loss of RGC function following injury, as measured in vivo with the electroretinogram. RGC dysfunction in retinas from mice on the HFS diet was accompanied by activation of retinal macroglia but was not associated with neuronal cell loss. Exercising mice by swimming did not prevent HFS-induced RGC dysfunction in response to injury. This study shows for the first time that a short term increase in dietary fat and sucrose enhances the vulnerability of RGCs to dysfunction and cell stress after an acute injury, and that this is independent of obesity or hyperglycemia. Furthermore, our results suggest that detrimental effects of diet predominate over protective effects of exercise. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Porous graphene current collectors filled with silicon as high-performance lithium battery anode

    Science.gov (United States)

    Ababtain, Khalid; Babu, Ganguli; Susarla, Sandhya; Gullapalli, Hemtej; Masurkar, Nirul; Ajayan, Pulickel M.; Mohana Reddy Arava, Leela

    2018-01-01

    Despite the massive success for high energy density, the charge–discharge current rate performance of the lithium-ion batteries are still a major concern owing to inherent sluggish Li-ion kinetics. Herein, we demonstrate three-dimensional porous electrodes engineered on highly conductive graphene current collectors to enhance the Li-ion conductivity, thereby c-rate performance. Such high-quality graphene provides surface area for loading a large amount of electrochemically active material and strong adhesion with the electrode. The synergism of porous structure and conductive current collector enables us to realize high-performance new-generation silicon anodes with a high energy density of 1.8 mAh cm‑2. Further, silicon electrodes revealed with excellent current rates up to 5C with a capacity of 0.37 mAh cm‑2 for 500 nm planar thickness.

  9. Enhancing Short-Term Recovery After High-Intensity Anaerobic Exercise.

    Science.gov (United States)

    Al-Nawaiseh, Ali M; Pritchett, Robert C; Bishop, Philip A

    2016-02-01

    This study examined the effects of antioxidant vitamins, ibuprofen, cold water submersion, and whey protein administered simultaneously on short-term recovery. Competitive athletes (n = 22) performed the protocol in 2 occasions (treatment and control) separated by 15 days in counterbalanced crossover design. Each occasion consisted of morning and afternoon sessions (AM and PM). In each session, participants performed 2 bouts of high-intensity anaerobic cycling separated by 30 minutes of rest. Each bout consisted of 3 Wingate tests (3 × 30-second Wingate tests) with 3 minutes of active recovery in between. Power output, rated perceived exertion (RPE), and pain scores were averaged and compared between the 2 sessions (AM vs. PM) and between the treatment vs. control (4 bouts). Creatine kinase (CK) levels were also measured 24 hours after the AM bout. Power output, CK, muscle soreness, and RPE were measured as recovery indices. Creatine kinase increased (p < 0.001) in both treatment and control 24 hours after the AM session. Performance results in the PM session for treatment/control were 832.5 ± 198.7/813.3 ± 187.6 W for peak power (PP), and 497.85 ± 120.7/486.1 ± 115 W for mean power (MP). Treatment was effective in maintaining MP (p = 0.034) in the PM sessions, but there was no significant effect of treatment on PP (p = 0.193), CK (p = 0.08), pain (p = 0.12), or RPE (p = 0.45). Treatment was helpful in protecting performance, but this was apparently not due to reduced muscle soreness or damage.

  10. Verification & Validation of High-Order Short-Characteristics-Based Deterministic Transport Methodology on Unstructured Grids

    Energy Technology Data Exchange (ETDEWEB)

    Azmy, Yousry [North Carolina State Univ., Raleigh, NC (United States); Wang, Yaqi [North Carolina State Univ., Raleigh, NC (United States)

    2013-12-20

    The research team has developed a practical, high-order, discrete-ordinates, short characteristics neutron transport code for three-dimensional configurations represented on unstructured tetrahedral grids that can be used for realistic reactor physics applications at both the assembly and core levels. This project will perform a comprehensive verification and validation of this new computational tool against both a continuous-energy Monte Carlo simulation (e.g. MCNP) and experimentally measured data, an essential prerequisite for its deployment in reactor core modeling. Verification is divided into three phases. The team will first conduct spatial mesh and expansion order refinement studies to monitor convergence of the numerical solution to reference solutions. This is quantified by convergence rates that are based on integral error norms computed from the cell-by-cell difference between the code’s numerical solution and its reference counterpart. The latter is either analytic or very fine- mesh numerical solutions from independent computational tools. For the second phase, the team will create a suite of code-independent benchmark configurations to enable testing the theoretical order of accuracy of any particular discretization of the discrete ordinates approximation of the transport equation. For each tested case (i.e. mesh and spatial approximation order), researchers will execute the code and compare the resulting numerical solution to the exact solution on a per cell basis to determine the distribution of the numerical error. The final activity comprises a comparison to continuous-energy Monte Carlo solutions for zero-power critical configuration measurements at Idaho National Laboratory’s Advanced Test Reactor (ATR). Results of this comparison will allow the investigators to distinguish between modeling errors and the above-listed discretization errors introduced by the deterministic method, and to separate the sources of uncertainty.

  11. A High-Sensitivity Current Sensor Utilizing CrNi Wire and Microfiber Coils

    Directory of Open Access Journals (Sweden)

    Xiaodong Xie

    2014-05-01

    Full Text Available We obtain an extremely high current sensitivity by wrapping a section of microfiber on a thin-diameter chromium-nickel wire. Our detected current sensitivity is as high as 220.65 nm/A2 for a structure length of only 35 μm. Such sensitivity is two orders of magnitude higher than the counterparts reported in the literature. Analysis shows that a higher resistivity or/and a thinner diameter of the metal wire may produce higher sensitivity. The effects of varying the structure parameters on sensitivity are discussed. The presented structure has potential for low-current sensing or highly electrically-tunable filtering applications.

  12. High-current electron gun with a planar magnetron integrated with an explosive-emission cathode

    Science.gov (United States)

    Kiziridi, P. P.; Ozur, G. E.

    2017-05-01

    A new high-current electron gun with plasma anode and explosive-emission cathode integrated with planar pulsed powered magnetron is described. Five hundred twelve copper wires 1 mm in diameter and 15 mm in height serve as emitters. These emitters are installed on stainless steel disc (substrate) with 3-mm distance between them. Magnetron discharge plasma provides increased ion density on the periphery of plasma anode formed by high-current Penning discharge ignited within several milliseconds after starting of the magnetron discharge. The increased on the periphery ion density improves the uniformity of high-current electron beam produced in such an electron gun.

  13. Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse

    Energy Technology Data Exchange (ETDEWEB)

    Grishkov, V. E.; Uryupin, S. A., E-mail: uryupin@sci.lebedev.ru [Russian Academy of Sciences, Lebedev Physical Institute (Russian Federation)

    2017-03-15

    Excitation of plasma waves by nonlinear currents induced by a high-frequency electromagnetic pulse is analyzed within the kinetic approach. It is shown that the most efficient source of plasma waves is the nonlinear current arising due to the gradient of the energy density of the high-frequency field. Generation of plasma waves by the drag current is usually less efficient but not negligibly small at relatively high frequencies of electron–ion collisions. The influence of electron collisions on the excitation of plasma waves by pulses of different duration is described quantitatively.

  14. A quantum wave based compact modeling approach for the current in ultra-short DG MOSFETs suitable for rapid multi-scale simulations

    Science.gov (United States)

    Hosenfeld, Fabian; Horst, Fabian; Iñíguez, Benjamín; Lime, François; Kloes, Alexander

    2017-11-01

    Source-to-drain (SD) tunneling decreases the device performance in MOSFETs falling below the 10 nm channel length. Modeling quantum mechanical effects including SD tunneling has gained more importance specially for compact model developers. The non-equilibrium Green's function (NEGF) has become a state-of-the-art method for nano-scaled device simulation in the past years. In the sense of a multi-scale simulation approach it is necessary to bridge the gap between compact models with their fast and efficient calculation of the device current, and numerical device models which consider quantum effects of nano-scaled devices. In this work, an NEGF based analytical model for nano-scaled double-gate (DG) MOSFETs is introduced. The model consists of a closed-form potential solution of a classical compact model and a 1D NEGF formalism for calculating the device current, taking into account quantum mechanical effects. The potential calculation omits the iterative coupling and allows the straightforward current calculation. The model is based on a ballistic NEGF approach whereby backscattering effects are considered as second order effect in a closed-form. The accuracy and scalability of the non-iterative DG MOSFET model is inspected in comparison with numerical NanoMOS TCAD data for various channel lengths. With the help of this model investigations on short-channel and temperature effects are performed.

  15. Biocompatible, high precision, wideband, improved Howland current source with lead-lag compensation.

    Science.gov (United States)

    Tucker, A S; Fox, R M; Sadleir, R J

    2013-02-01

    The Howland current pump is a popular bioelectrical circuit, useful for delivering precise electrical currents. In applications requiring high precision delivery of alternating current to biological loads, the output impedance of the Howland is a critical figure of merit that limits the precision of the delivered current when the load changes. We explain the minimum operational amplifier requirements to meet a target precision over a wide bandwidth. We also discuss effective compensation strategies for achieving stability without sacrificing high frequency output impedance. A current source suitable for Electrical Impedance Tomography (EIT) was simulated using a SPICE model, and built to verify stable operation. This current source design had stable output impedance of 3.3 MΩ up to 200 kHz, which provides 80 dB precision for our EIT application. We conclude by noting the difficulty in measuring the output impedance, and advise verifying the plausibility of measurements against theoretical limitations.

  16. Conductor of high electrical current at high temperature in oxygen and liquid metal environment

    Science.gov (United States)

    Powell, IV, Adam Clayton; Pati, Soobhankar; Derezinski, Stephen Joseph; Lau, Garrett; Pal, Uday B.; Guan, Xiaofei; Gopalan, Srikanth

    2016-01-12

    In one aspect, the present invention is directed to apparatuses for and methods of conducting electrical current in an oxygen and liquid metal environment. In another aspect, the invention relates to methods for production of metals from their oxides comprising providing a cathode in electrical contact with a molten electrolyte, providing a liquid metal anode separated from the cathode and the molten electrolyte by a solid oxygen ion conducting membrane, providing a current collector at the anode, and establishing a potential between the cathode and the anode.

  17. 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.

  18. A New High-Speed Low Distortion Switched-Current Cell

    DEFF Research Database (Denmark)

    Shah, Peter Jivan; Toumazou, Christofer

    1996-01-01

    A new switched-current cell is presented which simultaneously offers high speed, low distortion, low gain error, and a virtual ground input. In a simulation example 0.01% distortion was achieved at 50MHz sampling rate which makes the cell very well suited for high accuracy high speed filtering...

  19. Short-Wave Diathermy Pretreatment and Inflammatory Myokine Response After High-Intensity Eccentric Exercise.

    Science.gov (United States)

    Vardiman, John P; Moodie, Nicole; Siedlik, Jacob A; Kudrna, Rebecca A; Graham, Zachary; Gallagher, Philip

    2015-06-01

    Various modalities have been used to pretreat skeletal muscle to attenuate inflammation. To determine the effects of short-wave diathermy (SWD) preheating treatment on inflammation and stress markers after eccentric exercise. Controlled laboratory study. University laboratory setting. Fifteen male (age = 22 ± 4.9 years, height = 179.75 ± 9.56 cm, mass = 82.22 ± 12.67 kg) college-aged students. Seven participants were selected randomly to receive 40 minutes of SWD heat treatment (HT), and 8 participants served as the control (CON) group and rested without SWD. Both groups completed 7 sets of 10 repetitions of a high-intensity eccentric exercise protocol (EEP) at 120% of the 1-repetition maximum (1-RM) leg extension. We biopsied muscles on days 1, 3 (24 hours post-EEP), and 4 (48 hours post-EEP) and collected blood samples on days 1, 2 (4 hours post-EEP), 3, and 4. We determined 1-RM on day 2 (24 hours post-SWD) and measured 1-RM on days 3 and 4. We analyzed the muscle samples for interleukin 6 (IL-6), tumor necrosis factor α, and heat shock protein 70 and the blood for serum creatine kinase. We found a group × time interaction for intramuscular IL-6 levels after SWD (F2,26 = 7.13, P = .003). The IL-6 decreased in HT (F1,6 = 17.8, P = .006), whereas CON showed no change (P > .05). We found a group × time interaction for tumor necrosis factor α levels (F2,26 = 3.71, P = .04), which increased in CON (F2,14 = 7.16, P = .007), but saw no changes for HT (P > .05). No group × time interactions were noted for 1-RM, heat shock protein 70, or creatine kinase (P > .05). The SWD preheating treatment provided a treatment effect for intramuscular inflammatory myokines induced through high-intensity eccentric exercise but did not affect other factors associated with intense exercise and inflammation.

  20. Surface circulation in the Iroise Sea (western Brittany) derived from high resolution current mapping by HF radars

    Science.gov (United States)

    Sentchev, Alexei; Forget, Philippe; Barbin, Yves; Marié, Louis; Ardhuin, Fabrice

    2010-05-01

    The use of high frequency radar (HFR) systems for near-real-time coastal ocean monitoring necessities that short time scale motions of the radar-derived velocities are better understood. While the ocean radar systems are able to describe coastal flow patterns with unprecedented details, the data they produce are often too sparse or gappy for applications such as the identification of coherent structures and fronts or understanding transport and mixing processes. In this study, we address two challenges. First, we report results from the HF radar system (WERA) which is routinely operating since 2006 on the western Brittany coast to monitor surface circulation in the Iroise Sea, over an area extending up to 100 km offshore. To obtain more reliable records of vector current fields at high space and time resolution, the Multiple Signal Classification (MUSIC) direction finding algorithm is employed in conjunction with the variational interpolation (2dVar) of radar-derived velocities. This provides surface current maps at 1 km spacing and time resolution of 20 min. Removing the influence of the sea state on radar-derived current measurements is discussed and performed on some data sequences. Second, we examine in deep continuous 2d velocity records for a number of periods, exploring the different modes of variability of surface currents in the region. Given the extent, duration, and resolution of surface current velocity measurements, new quantitative insights from various time series and spatial analysis on higher frequency kinematics will be discussed. By better characterizing the full spectrum of flow regimes that contribute to the surface currents and their shears, a more complete picture of the circulation in the Iroise Sea can be obtained.

  1. On Current Conversion between Particle Rapidity and Pseudorapidity Distributions in High Energy Collisions

    Directory of Open Access Journals (Sweden)

    Fu-Hu Liu

    2013-01-01

    Full Text Available In high energy collisions, one usually needs to give a conversion between the particle rapidity and pseudorapidity distributions. Currently, two equivalent conversion formulas are used in experimental and theoretical analyses. An investigation in the present work shows that the two conversions are incomplete. Then, we give a revision on the current conversion between the particle rapidity and pseudorapidity distributions.

  2. Hybrid High-Temperature Superconductor Current Leads for Space Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Tai-Yang Research Company (TYRC) of Tallahassee, Florida proposes to build hybrid high-temperature superconducting current leads for space applications,...

  3. Hybrid High-Temperature Superconductor Current Leads for Space Applications Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Tai-Yang Research Company (TYRC) proposes to address the need for high temperature superconducting (HTS) current leads used in an adiabatic demagnetization...

  4. Total pancreatectomy: Short- and long-term outcomes at a high-volume pancreas center.

    Science.gov (United States)

    Zakaria, Hazem M; Stauffer, John A; Raimondo, Massimo; Woodward, Timothy A; Wallace, Michael B; Asbun, Horacio J

    2016-09-27

    To identify the current indications and outcomes of total pancreatectomy at a high-volume center. A single institutional retrospective study of patients undergoing total pancreatectomy from 1995 to 2014 was performed. One hundred and three patients underwent total pancreatectomy for indications including: Pancreatic ductal adenocarcinoma (n = 42, 40.8%), intraductal papillary mucinous neoplasms (n = 40, 38.8%), chronic pancreatitis (n = 8, 7.8%), pancreatic neuroendocrine tumors (n = 7, 6.8%), and miscellaneous (n = 6, 5.8%). The mean age was 66.2 years, and 59 (57.3%) were female. Twenty-four patients (23.3%) underwent a laparoscopic total pancreatectomy. Splenic preservation and portal vein resection and reconstruction were performed in 24 (23.3%) and 18 patients (17.5%), respectively. The 90 d major complications, readmission, and mortality rates were 32%, 17.5%, and 6.8% respectively. The 1-, 3-, 5-, and 7-year survival for patients with benign indications were 84%, 82%, 79.5%, and 75.9%, and for malignant indications were 64%, 40.4%, 34.7% and 30.9%, respectively. Total pancreatectomy, including laparoscopic total pancreatectomy, appears to be an appropriate option for selected patients when treated at a high-volume pancreatic center and through a multispecialty approach.

  5. An Examination of the Structure of the Career Decision Self-Efficacy Scale (Short Form) among Italian High School Students

    Science.gov (United States)

    Presti, Alessandro Lo; Pace, Francesco; Mondo, Marina; Nota, Laura; Casarubia, Provvidenza; Ferrari, Lea; Betz, Nancy E.

    2013-01-01

    This study aims to evaluate the factor structure of Career Decision Self-Efficacy scale-short form in a sample of Italian high school adolescents. confirmatory factor analysis (CFA) was used to test the degree to which a one-factor structure and a five-factor structure provided the best fit. In view of available research the five-factor structure…

  6. Vegetation response to a short interval between high-severity wildfires in a mixed-evergreen forest

    Science.gov (United States)

    Daniel C. Donato; Joseph B. Fontaine; W. Douglas Robinson; J. Boone Kauffman; Beverly E. Law

    2009-01-01

    Variations in disturbance regime strongly influence ecosystem structure and function. A prominent form of such variation is when multiple high-severity wildfires occur in rapid succession (i.e. short-interval (SI) severe fires, or ‘re-burns’). These events have been proposed as key mechanisms altering successional rates and pathways....

  7. Numerical simulation of screening current distribution in HTS tape of high field magnet

    OpenAIRE

    Itoh, Ryusei; Oga, Yuki; Noguchi, So; Igarashi, Hajime; Ueda, Hiroshi

    2013-01-01

    In recent years, properties of high temperature superconducting (HTS) tapes, especially in-field performance and mechanical strength, have been continuously improved. The HTS tapes have been widely used for high field (>20 T) magnet researches and there are several technical challenges including field attenuation of an HTS magnet by screening currents induced within the HTS tapes. Several publications reported that the screening currents, induced by penetration of self magnetic fields into HT...

  8. Theoretical Analysis on the Short-Circuit Current of Inverter-Interfaced Renewable Energy Generators with Fault-Ride-Through Capability

    Directory of Open Access Journals (Sweden)

    Sumei Liu

    2017-12-01

    Full Text Available Renewable energy generators (REGs usually employ power electronic devices for connecting with the grid, which makes their fault characteristics completely different from those of conventional synchronous generators. In the existing studies, the simulation methods are mainly adopted to analyze fault current contribution from REG. As a result, the explanations on the fault current show diversity and cannot reach a recognized standard. The REGs’ mathematical model in relay-setting calculations is unknown. Thus, this paper theoretically analyses the fault current characteristics of inverter-interfaced REGs (IIREGs with fault-ride-through (FRT ability. In order to understand the fault current characteristics, the FRT control strategy for IIREGs is firstly studied. Then the characteristics of high-frequency and fundamental-frequency fault currents from IIREGs are theoretically analyzed after and during the faults. The affecting factors and duration time of different frequency fault currents are, respectively, revealed. Further, the mathematical expression of fundamental fault currents from IIREGs are derived and verified based on the experimental test bench. The results can be used in estimating the IIREGs’ fault contributions and developing the fault calculation model.

  9. Influence of contact surface quality and contact material on the contact resistances of high current connections

    Energy Technology Data Exchange (ETDEWEB)

    Lange, Christian, E-mail: c.lange@kit.edu [Karlsruhe Institute of Technology (KIT), Institute for Technical Physics, Karlsruhe (Germany); Fietz, Walter H.; Gröner, Frank [Karlsruhe Institute of Technology (KIT), Institute for Technical Physics, Karlsruhe (Germany)

    2013-10-15

    Highlights: ► Contact resistance at a connection between high current Cu–Cu and Cu–Al busbars at room temperature. ► Influence of the surface finish to contact resistance at a connection between high current busbars. ► Influence of gold plating to contact resistance at high current copper busbars. -- Abstract: At the connection between high current room temperature busbars, e.g. feeders for fusion machines, the contact resistance has to be low to avoid high electrical losses. Otherwise an excessive cooling is needed to prevent the busbar from local overheating caused by these losses. In order to determine the parameters, which are relevant to ensure a reproducible and reliable low contact resistance, detailed tests at room temperature with different high current connection types were performed. The contact resistance of aluminum–copper and copper–copper connection was measured for contact areas with different surfaces as e.g. polished, oxidized and gold plated contact area. In addition the change of the contact resistance during a long time operation and at different current densities was determined. Furthermore the effect of humidity, e.g. condensed water and over temperature, e.g. at an overload or a breakdown of the cooling system, on the contact resistance quality were analyzed.

  10. High Current Systems for HyperV and PLX Plasma Railguns

    Science.gov (United States)

    Brockington, S.; Case, A.; Messer, S.; Elton, R.; Witherspoon, F. D.

    2011-10-01

    HyperV is developing gas fed, pulsed, plasma railgun accelerators for PLX and other high momentum plasma applications. The present 2.5 cm square-bore plasma railgun forms plasma armatures from high density neutral gas (argon), preionizes it electrothermally, and accelerates the armature with 30 cm long parallel-plate railgun electrodes driven by a pulse forming network (PFN). Recent experiments have successfully formed and accelerated plasma armatures of ~4 mg at 40 km/s, with PFN currents of ~400 kA. In order to further increase railgun performance to the PLX design goal of 8 mg at 50 km/s, the PFN was upgraded to support currents of up to ~750 kA. A high voltage, high current linear array spark-gap switch and flexible, low-inductance transmission line were designed and constructed to handle the increased current load. We will describe these systems and present initial performance data from high current operation of the plasma rail gun from spectroscopy, interferometry, and imaging systems as well as pressure, magnetic field, and optical diagnostics. High current performance of railgun bore materials for electrodes and insulators will also be discussed as well as plans for upcoming experimentation with advanced materials. Supported by the U.S. DOE Joint Program in HEDLP.

  11. Behavior of AC High Voltage Polyamide Insulators: Evolution of Leakage Current in Different Surface Conditions

    OpenAIRE

    Mohammed El Amine Slama; Abderrahmane Beroual

    2015-01-01

    This paper is aimed at a systematic study of the leakage current of high voltage polyamide insulator string under different conditions of pollution for possible application in the electric locomotive systems. It is shown that in the case of clean/dry and clean/wetted insulators, the leakage current and applied voltage are linear. While in the case of pollution with saline spray, the leakage current and the applied voltage are not linear; the leakage current changes from a linear regime to a n...

  12. Behavior of AC High Voltage Polyamide Insulators: Evolution of Leakage Current in Different Surface Conditions

    Directory of Open Access Journals (Sweden)

    Mohammed El Amine Slama

    2015-01-01

    Full Text Available This paper is aimed at a systematic study of the leakage current of high voltage polyamide insulator string under different conditions of pollution for possible application in the electric locomotive systems. It is shown that in the case of clean/dry and clean/wetted insulators, the leakage current and applied voltage are linear. While in the case of pollution with saline spray, the leakage current and the applied voltage are not linear; the leakage current changes from a linear regime to a nonlinear regime up to total flashover of the insulators sting. Traces of erosion and tracking of insulators resulting of partial discharges are observed.

  13. Modular High Voltage Pulse Converter for Short Rise and Decay Times

    NARCIS (Netherlands)

    Mao, S.

    2018-01-01

    This thesis explores a modular HV pulse converter technology with short rise and decay times. A systematic methodology to derive and classify HV architectures based on a modularization level of power building blocks of the HV pulse converter is developed to summarize existing architectures and

  14. 77 FR 55880 - Prudential Short Duration High Yield Fund, Inc. and Prudential Investments LLC; Notice of...

    Science.gov (United States)

    2012-09-11

    ... outstanding preferred stock that such investment companies may issue. Applicants: Prudential Short Duration... seeks to qualify as a regulated investment company under the Code and that has both common stock and preferred stock outstanding designate the types of income, e.g., investment income and capital gains, in the...

  15. European Short-term Electricity Market Designs under High Penetration of Wind Power

    NARCIS (Netherlands)

    Chaves Avila, J.P.

    2014-01-01

    The EU has ambitious policies for decarbonization of the electricity sector. Due to recent technological developments, wind power already represents a significant share of the generation mix in some European countries. As a result, short-term electricity markets and balancing arrangements must be

  16. High-power CMOS current driver with accurate transconductance for electrical impedance tomography.

    Science.gov (United States)

    Constantinou, Loucas; Triantis, Iasonas F; Bayford, Richard; Demosthenous, Andreas

    2014-08-01

    Current drivers are fundamental circuits in bioimpedance measurements including electrical impedance tomography (EIT). In the case of EIT, the current driver is required to have a large output impedance to guarantee high current accuracy over a wide range of load impedance values. This paper presents an integrated current driver which meets these requirements and is capable of delivering large sinusoidal currents to the load. The current driver employs a differential architecture and negative feedback, the latter allowing the output current to be accurately set by the ratio of the input voltage to a resistor value. The circuit was fabricated in a 0.6- μm high-voltage CMOS process technology and its core occupies a silicon area of 0.64 mm (2) . It operates from a ± 9 V power supply and can deliver output currents up to 5 mA p-p. The accuracy of the maximum output current is within 0.41% up to 500 kHz, reducing to 0.47% at 1 MHz with a total harmonic distortion of 0.69%. The output impedance is 665 k Ω at 100 kHz and 372 k Ω at 500 kHz.

  17. High Speed Counter Current Chromatography-A Support free LC Technique

    OpenAIRE

    Garima Jain; Kona S Srinivasa; Aarti Sharma; Kaushal k Chandrul; Neha sethi; Ankit anand

    2009-01-01

    As separation of components is the major requirement of an analytical chemist, there is always a need of a convenient
    high throughput technique with minimum sample loss, high efficiency, high resolution, ease of sample
    recovery without contamination. This leads to the development of High Speed Counter Current Chromatography
    (HSCCC) in which stationary phase is liquid instead of solid that provides a lot of advantages...

  18. High impulse voltage and current measurement techniques fundamentals, measuring instruments, measuring methods

    CERN Document Server

    Schon, Klaus

    2013-01-01

    Equipment to be installed in electric power-transmission and distribution systems must pass acceptance tests with standardized high-voltage or high-current test impulses which simulate the stress on the insulation caused by external lightning discharges and switching operations in the grid. High impulse voltages and currents are also used in many other fields of science and engineering for various applications. Therefore, precise impulse-measurement techniques are necessary, either to prevent an over- or understressing of the insulation or to guarantee the effectiveness and quality of the application. The book deals with: principal generator circuits for generating high-voltage and high-current impulses measuring systems and their calibration according to IEC 60060 and IEC 62475 methods of estimating uncertainties of measurement mathematical and experimental basis for characterizing the transfer behavior of spatially extended systems used for measuring fast transients. This book is intended for engineers and ...

  19. Charged weak currents

    CERN Document Server

    Turlay, René

    1979-01-01

    In this review of charged weak currents the author concentrates on inclusive high energy neutrino physics. The authors discusses the general structure of charged currents, new results on total cross- sections, the Callan-Gross relation, antiquark distributions, scaling violations and tests of QCD. A very short summary on multilepton physics is given. (44 refs).

  20. High Density Schottky Barrier Infrared Charge-Coupled Device (IRCCD) Sensors For Short Wavelength Infrared (SWIR) Applications At Intermediate Temperature

    Science.gov (United States)

    Elabd, H.; Villani, T. S.; Tower, J. R.

    1982-11-01

    Monolithic 32 x 64 and 64 x 128 palladium silicide (Pd2Si) interline transfer IRCCDs sensitive in the 1-3.5 pm spectral band have been developed. This silicon imager exhibits a low response nonuniformity of typically 0.2-1.6% rms, and has been operated in the temperature range between 40-140K. Spectral response measurements of test Pd2Si p-type Si devices yield quantum efficiencies of 7.9% at 1.25 μm, 5.6% at 1.65 μm and 2.2% at 2.22 μm. Improvement in quantum efficiency is expected by optimizing the different structural parameters of the Pd2Si detectors. The spectral response of the Pd2Si detectors fit a modified Fowler emission model. The measured photo-electric barrier height for the Pd2Si detector is ≍0.34 eV and the measured quantum efficiency coefficient, C1, is 19%/eV. The dark current level of Pd2Si Schottky barrier focal plane arrays (FPAs) is sufficiently low to enable operation at intermediate tem-peratures at TV frame rates. Typical dark current level measured at 120K on the FPA is 2 nA/cm2. The Pd2Si Schottky barrier imaging technology has been developed for satellite sensing of earth resources. The operating temperature of the Pd2Si FPA is compatible with passive cooler performance. In addition, high density Pd2Si Schottky barrier FPAs are manufactured with high yield and therefore represent an economical approach to short wavelength IR imaging. A Pd2Si Schottky barrier image sensor for push-broom multispectral imaging in the 1.25, 1.65, and 2.22 μm bands is being studied. The sensor will have two line arrays (dual band capability) of 512 detectors each, with 30 μm center-to-center detector spacing. The device will be suitable for chip-to-chip abutment, thus providing the capability to produce large, multiple chip focal planes with contiguous, in-line sensors.

  1. High power test results of the first SRRC/ANL high current L-band RF gun.

    Energy Technology Data Exchange (ETDEWEB)

    Ho, C. H.

    1998-09-11

    A joint program is underway between the SRRC (Synchrotrons Radiation Research Center, Taiwan) and ANL (Argonne National Laboratory, USA) for developing a high current L-band photocathode rf guns. We have constructed an L-Band (1.3 Ghz), single cell rf photocathode gun and conducted low power tests at SRRC. High power rf conditioning of the cavity has been completed at ANL. In this paper we report on the construction and high power test results. So far we have been able to achieve > 120 MV/m axial electric field with minimal dark current. This gun will be used to replace the AWA (Argonne Wakefield Accelerator)[l] high current gun.

  2. High temperature, short time pasteurization temperatures inversely affect bacterial numbers during refrigerated storage of pasteurized fluid milk.

    Science.gov (United States)

    Ranieri, M L; Huck, J R; Sonnen, M; Barbano, D M; Boor, K J

    2009-10-01

    The grade A Pasteurized Milk Ordinance specifies minimum processing conditions of 72 degrees C for at least 15 s for high temperature, short time (HTST) pasteurized milk products. Currently, many US milk-processing plants exceed these minimum requirements for fluid milk products. To test the effect of pasteurization temperatures on bacterial numbers in HTST pasteurized milk, 2% fat raw milk was heated to 60 degrees C, homogenized, and treated for 25 s at 1 of 4 different temperatures (72.9, 77.2, 79.9, or 85.2 degrees C) and then held at 6 degrees C for 21 d. Aerobic plate counts were monitored in pasteurized milk samples at d 1, 7, 14, and 21 postprocessing. Bacterial numbers in milk processed at 72.9 degrees C were lower than in milk processed at 85.2 degrees C on each sampling day, indicating that HTST fluid milk-processing temperatures significantly affected bacterial numbers in fluid milk. To assess the microbial ecology of the different milk samples during refrigerated storage, a total of 490 psychrotolerant endospore-forming bacteria were identified using DNA sequence-based subtyping methods. Regardless of processing temperature, >85% of the isolates characterized at d 0, 1, and 7 postprocessing were of the genus Bacillus, whereas more than 92% of isolates characterized at d 14 and 21 postprocessing were of the genus Paenibacillus, indicating that the predominant genera present in HTST-processed milk shifted from Bacillus spp. to Paenibacillus spp. during refrigerated storage. In summary, 1) HTST processing temperatures affected bacterial numbers in refrigerated milk, with higher bacterial numbers in milk processed at higher temperatures; 2) no significant association was observed between genus isolated and pasteurization temperature, suggesting that the genera were not differentially affected by the different processing temperatures; and 3) although typically present at low numbers in raw milk, Paenibacillus spp. are capable of growing to numbers that can

  3. A HIGH PERFORMANCE FULLY DIFFERENTIAL PURE CURRENT MODE OPERATIONAL AMPLIFIER AND ITS APPLICATIONS

    Directory of Open Access Journals (Sweden)

    SEYED JAVAD AZHARI

    2012-08-01

    Full Text Available In this paper a novel high performance all current-mode fully-differential (FD Current mode Operational Amplifier (COA in BIPOLAR technology is presented. The unique true current mode simple structure grants the proposed COA the largest yet reported unity gain frequency while providing low voltage low power operation. Benefiting from some novel ideas, it also exhibits high gain, high common mode rejection ratio (CMRR, high power supply rejection ratio (PSRR, high output impedance, low input impedance and most importantly high current drive capability. Its most important parameters are derived and its performance is proved by PSPICE simulations using 0.8 μm BICMOS process parameters at supply voltage of ±1.2V indicating the values of 82.4 dB,52.3º, 31.5 Ω, 31.78 MΩ, 179.2 dB, 2 mW and 698 MHz for gain, phase margin, input impedance, output impedance, CMRR, power and unity gain frequency respectively. Its CMRR also shows very high frequency of 2.64 GHz at zero dB. Its very high PSRR+/PSRR- of 182 dB/196 dB makes the proposed COA a highly suitable block in Mixed-Mode (SOC chips. Most favourably it can deliver up to ±1.5 mA yielding a high current drive capability exceeding 25. To demonstrate the performance of the proposed COA, it is used to realize a constant bandwidth voltage amplifier and a high performance Rm amplifier.

  4. Development and characterization of diamond film and compound metal surface high current photocathodes

    Energy Technology Data Exchange (ETDEWEB)

    Shurter, R.P.; Moir, D.C.; Devlin, D.J.; Springer, R.W.; Archuleta, T.A.

    1997-09-01

    High current photocathodes operating in vacuum environments as high as 8xE-5 torr are being developed at Los Alamos for use in a new generation of linear induction accelerators. We report quantum efficiencies in wide bandgap semiconductors, pure metals, and compound metal surfaces photocathode materials illuminated by ultraviolet laser radiation.

  5. Measurement of neutral current cross-sections at high Bjorken-x with ...

    Indian Academy of Sciences (India)

    2012-11-16

    Nov 16, 2012 ... journal of. November 2012 physics pp. 1325–1329. Measurement of neutral current cross-sections at high. Bjorken-x with the ZEUS detector at HERA ... The kinematic range accessible to the measurement is determined by the resolution on x and Q2. In high-x events, the electron detection efficiency is ...

  6. Predicting high-current disruptions on NSTX with stacked regression trees

    Science.gov (United States)

    Barbour, Nathaniel; Kleijwegt, Kornee; Lupin-Jimenez, Leonard; Kolemen, Egemen

    2017-10-01

    Disruption mitigation and avoidance are critical objectives for the successful operation of ITER. Of particular interest is the prospect of predicting disruptions during its first high-plasma-current experiments, when only low-current data will be available. Toward achieving those objectives, data from an initial sample of 1,000 shots are separated into two groups by plasma current. Four regression tree algorithms are then used as disruption predictors: AdaBoost, random forests, extremely randomized trees, and bootstrap aggregating (``bagging''). Each algorithm is trained using data from low-current shots and used to predict disruptions in the sample of high-current shots. To improve prediction accuracy, multiple methods of scaling the input signal data are examined. The creation of a meta-estimator from the predictions of the four regression tree algorithms is explored. A future extension is to predict high-current disruptions on other devices using a meta-estimator trained with low-current data from NSTX and NSTX-U. Supported by the US DOE Contract No. DE-AC02-09CH11466.

  7. Does high level youth sports participation increase the risk of femoroacetabular impingement? A review of the current literature.

    Science.gov (United States)

    de Silva, Viran; Swain, Michael; Broderick, Carolyn; McKay, Damien

    2016-03-11

    Sports participation can be an integral part of adolescent development with numerous positive short and long-term effects. Despite these potential benefits very high levels of physical activity, during skeletal maturation, have been proposed as a possible cause of cam-type femoroacetabular impingement (FAI). The influence of physical activity on the developing physis has been previously described both in animal studies and epidemiological studies of adolescent athletes. It is therefore important to determine whether the development of FAI is secondary to excessive physical activity or a combination of a vulnerable physis and a set level of physical activity. A review of the current literature suggests that adolescent males participating in ice-hockey, basketball and soccer, training at least three times a week, are at greater risk than their non-athletic counterparts of developing the femoral head-neck deformity associated with femoroacetabular impingement.

  8. A high voltage, constant current stimulator for electrocutaneous stimulation through small electrodes.

    Science.gov (United States)

    Poletto, C J; Van Doren, C L

    1999-08-01

    A high-voltage stimulator has been designed to allow transcutaneous stimulation of tactile fibers of the fingertip. The stimulator's output stage was based upon an improved Howland current pump topology, modified to allow high load impedances and small currents. The compliance voltage of approximately 800 V is achieved using commercially available high-voltage operational amplifiers. The output current accuracy is better than +/- 5% over the range of 1 to 25 mA for 30 microseconds or longer pulses. The rise time for square pulses is less than 1 microsecond. High-voltage, common-mode, latch-up power supply problems and solutions are discussed. The stimulator's input stage is optically coupled to the controlling computer and complies with applicable safety standards for use in a hospital environment. The design presented here is for monophasic stimulation only, but could be modified for biphasic stimulation.

  9. Short Latency Gray Matter Changes in Voxel-Based Morphometry following High Frequent Visual Stimulation

    OpenAIRE

    Steffen Naegel; Tim Hagenacker; Nina Theysohn; Hans-Christoph Diener; Zaza Katsarava; Mark Obermann; Dagny Holle

    2017-01-01

    Magnetic resonance imaging studies using voxel-based morphometry (VBM) detected structural changes in the human brain within periods of months or weeks. The underlying molecular mechanisms of VBM findings remain unresolved. We showed that simple visual stimulation by an alternating checkerboard leads to instant, short-lasting alterations of the primary and secondary visual cortex detected by VBM. The rapidness of occurrence (i.e., within 10 minutes) rather excludes most of the proposed physio...

  10. Observation of nuclear dechanneling length reduction for high energy protons in a short bent crystal

    Directory of Open Access Journals (Sweden)

    W. Scandale

    2015-04-01

    Full Text Available Deflection of 400 GeV/c protons by a short bent silicon crystal was studied at the CERN SPS. It was shown that the dechanneling probability increases while the dechanneling length decreases with an increase of incident angles of particles relative to the crystal planes. The observation of the dechanneling length reduction provides evidence of the particle population increase at the top levels of transverse energies in the potential well of the planar channels.

  11. Quench performance of Fermilab high gradient quadrupole short models for the LHC Interaction Regions

    CERN Document Server

    Andreev, N; Bossert, R; Brandt, J; Chichili, D R; Di Marco, J; Fehér, S; Kerby, J S; Lamm, M J; Limon, P J; Nobrega, F; Orris, D; Novitski, I; Ozelis, J P; Peterson, T; Sabbi, G L; Schlabach, P; Strait, J B; Tartaglia, M; Tompkins, J C; Yadav, S; Zlobin, A V; Caspi, S; McInturff, A D; Scanlan, R M; Ghosh, A

    1999-01-01

    Fermilab and LBNL are in the midst of superconducting magnet R&D program to test and optimize the design of quadrupoles to be used in the LHC Interaction Region inner triplets. The magnets are required to deliver a 215 T/m gradient across a 70 mm aperture. Five quadrupole short models have been fabricated and four of them have been tested. This paper describes the last model design details and reports the results of the magnet quench performance study. (5 refs).

  12. Short Stature Is Associated With Overweight but Not With High Energy Intake in Low-Income Quilombola Women.

    Science.gov (United States)

    Ferreira, Haroldo da Silva; Luna, Andreza A; Florêncio, Telma Maria M T; Assunção, Monica L; Horta, Bernardo L

    2017-06-01

    Population exposed to chronic undernutrition in early life seems to be more susceptible to obesity in adulthood due to the development of mechanisms that improve the efficiency of energy use. Therefore, these individuals have relatively reduced energy requirements (thrifty phenotype). To investigate, among women living on severe socioeconomic vulnerability, whether short stature, a marker for undernutrition in early life, is associated with excess body weight but not with a high energy intake. This cross-sectional study, carried out between July and November 2008, evaluated 1308 women from all (N = 39) Quilombola communities of Alagoas. Adequacy of energy intake was estimated by the ratio between energetic ingestion and the estimated energy requirement (EER). The prevalence of short stature (≤ 154.8 cm) was 43.0% and 52.4% had excess body weight (body mass index ≥ 25 kg/m 2 ), being that 33.1% were overweight and 19.3% obese. Excess body weight was higher among women with short stature (56.6% vs 49.2%; P = .008), even after adjusting for age, energy intake, and per capita income (prevalence ratio = 1.16; 95% confidence interval = 1.04; 1.28). The ratio of energy intake/EER was independent of women's stature. Excess body weight among Quilombola women represents a serious health problem. Short stature was significantly associated with excess body weight but not with a high energy intake. "Thrifty phenotype" may be one of the plausible explanations for this finding.

  13. High-frequency, three-phase current controller implementation in an FPGA

    Energy Technology Data Exchange (ETDEWEB)

    Hartmann, M.; Round, S. D.; Kolar, J. W.

    2008-07-01

    Three phase rectifiers with switching frequencies of 500 kHz or more require high speed current controllers. At such high switching frequencies analog controllers as well as high speed digital signal processing (DSP) systems have limited performance. In this paper, two high speed current controller implementations using two different field-programmable gate arrays (FPGA) - one for switching frequencies up to 1 MHz and one for switching frequencies beyond 1 MHz - are presented to overcome this performance limitation. Starting with the digital system design all the blocks of the signal chain, containing analog-to-digital (A/D) interface, digital controller implementation using HW-multipliers and implementation of a novel high speed, high resolution pulse width modulation (PWM) are discussed and compared. Final measurements verify the performance of the controllers. (author)

  14. High magnetic field science and its application in the United States current status and future directions

    CERN Document Server

    National Research Council of the National Academies

    2013-01-01

    The Committee to Assess the Current Status and Future Direction of High Magnetic Field Science in the United States was convened by the National Research Council in response to a request by the National Science Foundation. This report answers three questions: (1) What is the current state of high-field magnet science, engineering, and technology in the United States, and are there any conspicuous needs to be addressed? (2) What are the current science drivers and which scientific opportunities and challenges can be anticipated over the next ten years? (3) What are the principal existing and planned high magnetic field facilities outside of the United States, what roles have U.S. high field magnet development efforts played in developing those facilities, and what potentials exist for further international collaboration in this area? A magnetic field is produced by an electrical current in a metal coil. This current exerts an expansive force on the coil, and a magnetic field is "high" if it challenges the str...

  15. Coherent control of injection currents in high-quality films of Bi2Se3

    Science.gov (United States)

    Bas, D. A.; Vargas-Velez, K.; Babakiray, S.; Johnson, T. A.; Borisov, P.; Stanescu, T. D.; Lederman, D.; Bristow, A. D.

    2015-01-01

    Films of the topological insulator Bi2Se3 are grown by molecular beam epitaxy with in-situ reflection high-energy electron diffraction. The films are shown to be high-quality by X-ray reflectivity and diffraction and atomic-force microscopy. Quantum interference control of photocurrents is observed by excitation with harmonically related pulses and detected by terahertz radiation. The injection current obeys the expected excitation irradiance dependence, showing linear dependence on the fundamental pulse irradiance and square-root irradiance dependence of the frequency-doubled optical pulses. The injection current also follows a sinusoidal relative-phase dependence between the two excitation pulses. These results confirm the third-order nonlinear optical origins of the coherently controlled injection current. Experiments are compared to a tight-binding band structure to illustrate the possible optical transitions that occur in creating the injection current.

  16. MIDOT: A novel probe for monitoring high-current flat transmission lines.

    Science.gov (United States)

    Omar, K; Novac, B M; Graneau, N; Senior, P; Smith, I R; Sinclair, M

    2016-12-01

    A novel inductive probe, termed MIDOT, was developed for monitoring high-current flat transmission lines. While being inexpensive the probe does not require calibration, is resistant to both shock waves and temperature variations, and it is easy to manufacture and mount. It generates strong output signals that are relatively easy to interpret and has a detection region limited to a pre-defined part of the transmission line. The theoretical background related to the MIDOT probes, together with their practical implementation in both preliminary experimentation and high-current tests, is also presented in the paper. The novel probe can be used to benchmark existing 2D numerical codes used in calculating the current distribution inside the conductors of a transmission line but can also easily detect an early movement of a transmission line component. The probe can also find other applications, such as locating the position of a pulsed current flowing through a thin wire.

  17. High Voltage Coil Current Sensor for DC-DC Converters Employing DDCC

    Directory of Open Access Journals (Sweden)

    M. Drinovsky

    2015-12-01

    Full Text Available Current sensor is an integral part of every switching converter. It is used for over-current protection, regulation and in case of multiphase converters for balancing. A new high voltage current sensor for coil-based current sensing in DC-DC converters is presented. The sensor employs DDCC with high voltage input stage and gain trimming. The circuit has been simulated and implemented in 0.35 um BCD technology as part of a multiphase DC-DC converter where its function has been verified. The circuit is able to sustain common mode voltage on the input up to 40 V, it occupies 0.387*0.345 mm2 and consumes 3.2 mW typically.

  18. High Order Voltage and Current Harmonic Mitigation Using the Modular Multilevel Converter STATCOM

    DEFF Research Database (Denmark)

    Kontos, Epameinondas; Tsolaridis, Georgios; Teodorescu, Remus

    2017-01-01

    Due to the increase of power electronic-based loads, the maintenance of high power quality poses a challenge in modern power systems. To limit the total harmonic distortion in the line voltage and currents at the point of the common coupling (PCC), active power filters are commonly employed....... This paper investigates the use of the multilevel modular converter (MMC) for harmonics mitigation due to its high bandwidth compared with conventional converters. A selective harmonics detection method and a harmonics controller are implemented, while the output current controller of the MMC is tuned...... to selectively inject the necessary harmonic currents. Unlike previous studies, focus is laid on the experimental verification of the active filtering capability of the MMC. For this reason an MMC-based double-star STATCOM is developed and tested for two representative case studies, i.e., for grid currents...

  19. A Low Voltage High Gain Transformer Noise-Canceling Current Mode Ultrawideband CMOS Low Noise Amplifier

    Science.gov (United States)

    Sun, Jingru; Cao, Xiaodong; Wang, Chunhua; Liu, Jinjiang; Zhao, Manfeng

    2012-03-01

    This paper presents a novel current mode differential UWB LNA. A common-gate stage with transformer realizes a low noise input matching and produces a current gain. The output of the LNA is differential current, which can avoid the current-to-voltage conversion. The LNA is simulated with TSMC 0.18 μm RF CMOS process. Simulation results show that the max noise figure is only 2.65 dB, transconductance gain is larger than 18.7 dB, input reflection coefficient is lower than -9.9 dB, and third order input intercept point is about 2.8 dBm over 3-5 GHz. With a voltage of 0.8 V, the power consumption is 11 mW. A comparison with conventional UWB LNA shows that this LNA has advantages of low voltage, low noise, high gain, and high linearity.

  20. A High Performance CMOS Current Mirror Circuit with Neuron MOSFETs and a Transimpedance Amplifier

    Science.gov (United States)

    Shimizu, Akio; Ishikawa, Yohei; Fukai, Sumio; Aikawa, Masayoshi

    In this paper, we propose a high accuracy current mirror circuit suitable for a low-voltage operation. The proposed circuit has a novel negative feedback that is composed of neuron MOSFETs and a transimpedance amplifier. As a result, the proposed circuit achieves a high accuracy current mirror circuit. At the same time, the proposed circuit monitors an error current by a low voltage because the negative feedback operates in a current-mode. The performance of the proposed circuit is evaluated using HSPICE simulation with On-Semiconductor 1.48μm CMOS device parameters. Simulation results show that the output resistance of the proposed circuit is 5.79[GΩ] and minimum operating range is 0.3[V].

  1. High-resolution approaches to understanding short- and long-term trends in speleothem geochemical records

    Science.gov (United States)

    Fairchild, I. J.; Baker, A.; Mattey, D.; Spötl, C.; McDermott, F.; Baldini, L.; McMillan, E. A.; Frisia, S.; Andreo, B.; Borsato, A.

    2005-12-01

    Speleothem geochemical records can display and allow accurate dating of large-scale reorganizations of the climate system. Whilst large shifts in oxygen isotope composition in climatically sensitive (e.g. monsoonal) areas can be confidently interpreted in terms of the nature and sense of change, most more subtle variations cannot be unambiguously interpreted from low-resolution records. The use of high-resolution (sub-annual) records allows the processes involved in change to be more confidently interpreted and examples are given from work in several current European projects. Whilst some cave drip sites are well-mixed through the year, others reveal the seasonality of dripwater composition, and sub-annual oxygen isotope records can record the varying contributions of different seasons. When coupled with improved understanding of meteorological controls on rainfall composition, both the nature and mechanisms of climatic change can be tackled. Carbon isotopic patterns can be strongly influenced by seasonal patterns of cave ventilation that could reveal, e.g. intensity of winter cold. These are superimposed on the better-known vegetation effects. Trace element patterns depend strongly on cave physiology and both seasonal dryness and seasonally varying cave ventilation are key controls in different cases. Caves dominated by seasonal dryness lend themselves to parallel interpretation of longer-term aridity through Sr and Mg trends. In contrast, Alpine caves show interlinked hydrological and cave ventilation controls that can be distinguished by annual patterns of different trace species such as Pb, Y and P (hydrological control) and S (ventilation control). The multi-proxy approach calibrated with reference to modern dripwater behaviour and speleothems forming during the instrumental climatic period provides a sound basis for the interpretation of long-term trends.

  2. High Current, High frequency ECRIS development program for LHC heavy ion beam application

    CERN Document Server

    Angert, N; Hill, C; Haseroth, H; Girard, A; Hitz, D; Ludwig, P; Melin, G; Bouly, J L; Bruandet, J F; Chauvin, N; Curdy, Jean Claude; Geller, R; Lamy, T; Solé, P; Sortais, P; Ciavola, G; Gammino, S; Celona, L; Vieux-Rochaz, J L

    1999-01-01

    A research program with the aim of producing pulsed currents with hitherto unequalled intensity of Pb27+, with length and repetition ratecompatible with those desired by CERN (1 mAe / 400 ms / 10 Hz in the context of future heavy ion collisions at LHC) is organised in acollaboration between CERN/GSI/CEA-Grenoble and IN2P3-ISNG.Two main experimental programs will be carried out : (i) tests with the LNS-Catania team on the SERSE superconducting source with a 28 GHzgyrotron, (ii) tests on a non-superconducting source (new source at Grenoble) with a 28 GHz gyrotron. For this purpose CEA/DRFMC hasborrowed from CEA a 28 GHz - 10 kW gyrotron transmitter.The project includes also the construction of a source body, by ISNG, with conventional coils and permanent magnets for working at the frequencyof about 28 GHz and biased up to 60 kV. This source called PHOENIX will run on a test bench at ISN. PHOENIX is an improvement of thepresent ECR4-14.5 GHz/CERN source, having a mirror ratio R=2 at 14.5 GHz, and R=1.7 at 28 GHz...

  3. Analysis of high reverse currents of 4H-SiC Schottky-barrier diodes

    Science.gov (United States)

    Okino, Hiroyuki; Kameshiro, Norifumi; Konishi, Kumiko; Shima, Akio; Yamada, Ren-ichi

    2017-12-01

    Nickel (Ni), titanium (Ti), and molybdenum (Mo) 4H-silicon carbide Schottky-barrier diodes (SiC SBDs) were fabricated and used to investigate the relation between forward and reverse currents. Temperature dependence of reverse current follows a theory that includes tunneling in regard to thermionic emission, namely, temperature dependence is weak at low temperature but strong at high temperatures. On the other hand, the reverse currents of the Ni and Mo SBDs are higher than their respective currents calculated from their Schottky barrier heights (SBHs), whereas the reverse current of the Ti SBD agrees well with that calculated from its SBH. The cause of the high reverse currents was investigated from the viewpoints of low barrier patch, Gaussian distribution of barrier height (GD), thin surface barrier, and electron effective mass. The high reverse current of the Ni and Mo SBDs can be explained not in terms of a low-barrier patch, GD, or thin surface barrier but in terms of small effective masses. Investigation of crystal structures at the Schottky interface revealed a large lattice mismatch between the metals (Ni, Ti, or Mo) and SiC for the Ni and Mo SBDs. The small effective mass is possibly attributed to the large lattice mismatch, which might generate transition layers at the Schottky interface. It is concluded from these results that the lattice constant as well as the work function is an important factor in selecting the metal species as the Schottky metal for wide band-gap SBDs, for which tunneling current dominates reverse current.

  4. Research of Measurement Circuits for High Voltage Current Transformer Based on Rogowski Coils

    OpenAIRE

    Yan Bing; Wang Yutian; Li Hui; Wang Huixin; Chen Yiqiang

    2014-01-01

    The electronic current transformer plays an irreplaceable position in the field of relay protection and current measurement of the power system. Rogowski coils are used as sensor parts, and in order to improve the measurement accuracy and reliability, the circuits at the high voltage system are introduced and improved in this paper, including the analog integral element, the filtering circuit and the phase shift circuit. Simulations results proved the reliability and accuracy of the improved ...

  5. Research of Measurement Circuits for High Voltage Current Transformer Based on Rogowski Coils

    Directory of Open Access Journals (Sweden)

    Yan Bing

    2014-02-01

    Full Text Available The electronic current transformer plays an irreplaceable position in the field of relay protection and current measurement of the power system. Rogowski coils are used as sensor parts, and in order to improve the measurement accuracy and reliability, the circuits at the high voltage system are introduced and improved in this paper, including the analog integral element, the filtering circuit and the phase shift circuit. Simulations results proved the reliability and accuracy of the improved circuits.

  6. Calculation of surface leakage currents on high voltage insulators by ant colony algorithm-supported FEM

    OpenAIRE

    ÖZTÜRK, DURSUN; CEBECİ, MEHMET

    2015-01-01

    The weakness of the outer insulation at high voltages is the reduction of the surface resistance as a result of the environmental pollution yielding formation of flashover due to the surface leakage currents. In this study, it was shown how to calculate the surface leakage currents resulting in flashover in polluted insulators and therefore power cuts by means of the ant colony algorithm (ACA). For this purpose, first, field distribution on the sample insulator surface in question was defined...

  7. Measurements of high-current electron beams from X pinches and wire array Z pinches.

    Science.gov (United States)

    Shelkovenko, T A; Pikuz, S A; Blesener, I C; McBride, R D; Bell, K S; Hammer, D A; Agafonov, A V; Romanova, V M; Mingaleev, A R

    2008-10-01

    Some issues concerning high-current electron beam transport from the X pinch cross point to the diagnostic system and measurements of the beam current by Faraday cups are discussed. Results of computer simulation of electron beam propagation from the pinch to the Faraday cup give limits for the measured current for beams having different energy spreads. The beam is partially neutralized as it propagates from the X pinch to a diagnostic system, but within a Faraday cup diagnostic, space charge effects can be very important. Experimental results show evidence of such effects.

  8. Factors associated with current versus lifetime self-injury among high school and college students.

    Science.gov (United States)

    Taliaferro, Lindsay A; Muehlenkamp, Jennifer J

    2015-02-01

    We sought to identify factors associated with current versus lifetime nonsuicidal self-injury (NSSI) and factors that show consonant and distinct relationships with current NSSI for adolescents and young adults. Data came from a population-based survey of high school students (n = 9,985) and a national survey of college students (n = 7,801). Among both samples, factors associated with current NSSI included male gender, younger age, greater depressive symptoms, more hopelessness, and being the victim of a verbal or physical assault. For high school students, greater anxiety, and for college students, identifying as non-White, negative perceptions of one's weight, a same-sex sexual experience, and involvement in dating violence also distinguished the groups. Findings suggest that clinical and research assessments of lifetime NSSI might not extend to current behavior, and some differences exist in the factors associated with current behavior between adolescents and young adults. Clinical practice and prevention programming efforts should target certain intrapersonal and interpersonal factors associated with current NSSI among younger students during stressful transition periods in their lives, such as entering high school or college, when they might consider initiating or continuing this behavior. ©2014 The American Association of Suicidology.

  9. Introduction of the SHX-III System, a Single-Wafer High-Current Ion Implanter

    Science.gov (United States)

    Sugitani, Michiro; Tsukihara, Mitsukuni; Kabasawa, Mitsuaki; Ishikawa, Koji; Murooka, Hiroki; Ueno, Kazuyoshi

    2008-11-01

    The SHX-III system, categorized as a single-wafer high-current ion implanter, has been developed by SEN Corporation in order to meet all the requirements for high dose and relatively high mid-dose applications, including high-tilted multi-step implantation. Recently the three major advanced device types, namely logic devices, memory and imagers, started to require high-current ion implanters in diverse ways. The SHX-III is designed to fulfill such a variety of requirements in one system. The SHX-III has the same end station as the MC3-II/WR, SEN's latest medium current implanter, which has a mechanical throughput of 450 WPH. This capability and precise dose control system of the SHX-III causes dramatic productivity enhancement for application of mid-high dose, ranged between 5E13 to 2E14 atoms/cm2, usually performed by medium current ion implanters. In this paper the concept and performance of the SHX-III will be described, concerning influence of device characteristics. A concept and performance data of the SHX figure that this system can provide implant quality and productivity as far as the 32 nm node.

  10. Short term, high fat-feeding induced changes in white adipose tissue gene expression are highly predictive for long term changes

    NARCIS (Netherlands)

    Voigt, A.; Agnew, K.; Schothorst, van E.M.; Keijer, J.; Klaus, S.

    2013-01-01

    Scope - We aimed to evaluate the predictability of short-term (5 days) changes in epididymal white adipose tissue (eWAT) gene expression for long-term (12 weeks) changes induced by high-fat diet (HFD) feeding. Methods and results - Mice were fed semisynthetic diets containing 10 (low-fat diet) or 40

  11. Design, modification and test of the conduction cooled high-current current leads for the superconducting magnet

    Science.gov (United States)

    Peng, Quanling; Cheng, Da; Xu, Fengyu; Yang, Xiangchen; Wang, Ting; Wei, Xiaotao

    2017-09-01

    Conduction cooled current leads, which bring the current from the room temperature terminal down to the cryogenic environment, were used in common recently in large scale superconducting accelerators for its low cost, sample design and low heat load. In practice, the current lead is designed contained in a stainless steel tube. The heat load can be incepted in steps by thermal anchors, where one end is attached to the stainless steel tube, while the other end is connected with the cold shield of the cryomodule. Since the limitation of the welding technique, a thicker stainless steel tube needs to be used, and hence the thermal anchors cannot provide enough pressure to deform the tube enough to be in direct contact with the current lead, which may lead to temperature instability and bring extra heat load to the cryogenic system. An excellent option of epoxy filled current lead can realize the fully contact and reduce the heat load effectively. This paper will present the process of the current lead design, optimization, numerical simulation and cryogenic test, the test results show that the current lead can keep in a stable operation and low heat load.

  12. Ultra-short pulse reconstruction software in high power laser system

    Energy Technology Data Exchange (ETDEWEB)

    Galletti, M. [Physics Department of the University and INFN, Pisa (Italy); Galimberti, M. [Central Laser Facility, Rutherford Appleton Laboratory, Didcot (United Kingdom); Giulietti, D. [Physics Department of the University and INFN, Pisa (Italy)

    2015-07-15

    An ultra-short pulse reconstruction software, validated through a set of experimental measurements on the front-end of the Vulcan laser at the RAL Central Laser Facility is presented. The measurements were acquired in Target Area Petawatt of the Vulcan laser, both using a conventional autocorrelation technique and the GRENOUILLE technique in order to compare the results. The FWHM of the laser pulses considered came out to be comparable for the two techniques. In this experimental campaign for the first time a technique different from the autocorrelation one has been used for a PW class laser as Vulcan.

  13. Ultra-short pulse reconstruction software in high power laser system

    Science.gov (United States)

    Galletti, M.; Galimberti, M.; Giulietti, D.

    2015-07-01

    An ultra-short pulse reconstruction software, validated through a set of experimental measurements on the front-end of the Vulcan laser at the RAL Central Laser Facility is presented. The measurements were acquired in Target Area Petawatt of the Vulcan laser, both using a conventional autocorrelation technique and the GRENOUILLE technique in order to compare the results. The FWHM of the laser pulses considered came out to be comparable for the two techniques. In this experimental campaign for the first time a technique different from the autocorrelation one has been used for a PW class laser as Vulcan.

  14. High-power parametric conversion from near-infrared to short-wave infrared.

    Science.gov (United States)

    Billat, Adrien; Cordette, Steevy; Tseng, Yu-Pei; Kharitonov, Svyatoslav; Brès, Camille-Sophie

    2014-06-16

    We report the design of an all-fiber continuous wave Short-Wave Infrared source capable to output up to 700 mW of power at 1940 nm. The source is tunable over wavelength intervals comprised between 1850 nm and 2070 nm depending on its configuration. The output can be single or multimode while the optical signal to noise ratio ranges from 25 and 40 dB. The architecture is based on the integrated association of a fiber optical parametric amplifier and a Thulium doped fiber amplifier.

  15. High-resolution disruption halo current measurements using Langmuir probes in Alcator C-Mod

    Science.gov (United States)

    Tinguely, R. A.; Granetz, R. S.; Berg, A.; Kuang, A. Q.; Brunner, D.; LaBombard, B.

    2018-01-01

    Halo currents generated during disruptions on Alcator C-Mod have been measured with Langmuir ‘rail’ probes. These rail probes are embedded in a lower outboard divertor module in a closely-spaced vertical (poloidal) array. The dense array provides detailed resolution of the spatial dependence (~1 cm spacing) of the halo current distribution in the plasma scrape-off region with high time resolution (400 kHz digitization rate). As the plasma limits on the outboard divertor plate, the contact point is clearly discernible in the halo current data (as an inversion of current) and moves vertically down the divertor plate on many disruptions. These data are consistent with filament reconstructions of the plasma boundary, from which the edge safety factor of the disrupting plasma can be calculated. Additionally, the halo current ‘footprint’ on the divertor plate is obtained and related to the halo flux width. The voltage driving halo current and the effective resistance of the plasma region through which the halo current flows to reach the probes are also investigated. Estimations of the sheath resistance and halo region resistivity and temperature are given. This information could prove useful for modeling halo current dynamics.

  16. High Current, High Density Arc Plasma as a New Source for WiPAL

    Science.gov (United States)

    Waleffe, Roger; Endrizzi, Doug; Myers, Rachel; Wallace, John; Clark, Mike; Forest, Cary; WiPAL Team

    2016-10-01

    The Wisconsin Plasma Astrophysics Lab (WiPAL) has installed a new array of nineteen plasma sources (plasma guns) on its 3 m diameter, spherical vacuum vessel. Each gun is a cylindrical, molybdenum, washer-stabilized, arc plasma source. During discharge, the guns are maintained at 1.2 kA across 100 V for 10 ms by the gun power supply establishing a high density plasma. Each plasma source is fired independently allowing for adjustable plasma parameters, with densities varying between 1018 -1019 m-3 and electron temperatures of 5-15 eV. Measurements were characterized using a 16 tip Langmuir probe. The plasma source will be used as a background plasma for the magnetized coaxial plasma gun (MCPG), the Terrestrial Reconnection Experiment (TREX), and as the plasma source for a magnetic mirror experiment. Temperature, density, and confinement results will be presented. This work is supported by the DoE and the NSF.

  17. High-voltage integrated linear regulator with current sinking capabilities for portable ultrasound scanners

    DEFF Research Database (Denmark)

    Pausas, Guifre Vendrell; Llimos Muntal, Pere; Jørgensen, Ivan Harald Holger

    2017-01-01

    This paper presents a high-voltage integrated regulator capable of sinking current for driving pulse-triggered level shifters in drivers for ultrasound applications. The regulator utilizes a new topology with a feedback loop and a current sinking circuit to satisfy the requirements of the portable....... The proposed design has been implemented in high-voltage 0.18 μm process whithin an area of 0.11 mm2 and it is suitable for system-on-chip integration due to its low component count and the fully integrated design....

  18. Experimental observation of high-voltage, low-current vacuum arcs

    Energy Technology Data Exchange (ETDEWEB)

    Ivanov, R.Y.; Puzanov, S.V.; Yashnov, Y.M. [Scientific-Research Inst. Titan, Moscow (Russian Federation)

    1995-12-01

    A poorly explored type of discharge has been investigated in high vacuum (10{sup {minus}7} to 10{sup {minus}6} torr), with a DC high voltage across 0.2- to 0.8-mm gaps. The discharge has been found to be quite different from other widely known types of vacuum and gas discharges by the combination of its voltage-current characteristics (hyperbola-type), source and carriers of current (mostly electrons), and spatial potential distribution (a considerable electric field across the gap and a steep potential fall near the cathode).

  19. Experimental and theoretical analysis of an optical current sensor for high power systems

    Science.gov (United States)

    Brigida, A. C. S.; Nascimento, I. M.; Mendonça, S.; Costa, J. C. W. A.; Martinez, M. A. G.; Baptista, J. M.; Jorge, P. A. S.

    2013-03-01

    A magneto-optical sensor, using a dual quadrature polarimetric processing scheme, was evaluated for current metering and protection applications in high voltage lines. Sensor calibration and resolution were obtained in different operational conditions using illumination in the 1550-nm band. Results obtained indicated the feasibility of interrogating such sensor via the optical ground wire (OPGW) link installed in standard high power grids. The polarimetric bulk optical current sensor also was theoretically studied, and the effects of different sources of error considering practical deployment were evaluated. In particular, the interference from external magnetic fields in a tree-phase system was analyzed.

  20. Methods of high current magnetic field generator for transcranial magnetic stimulation application

    Energy Technology Data Exchange (ETDEWEB)

    Bouda, N. R., E-mail: nybouda@iastate.edu; Pritchard, J.; Weber, R. J.; Mina, M. [Department of Electrical and Computer engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2015-05-07

    This paper describes the design procedures and underlying concepts of a novel High Current Magnetic Field Generator (HCMFG) with adjustable pulse width for transcranial magnetic stimulation applications. This is achieved by utilizing two different switching devices, the MOSFET and insulated gate bipolar transistor (IGBT). Results indicate that currents as high as ±1200 A can be generated with inputs of +/−20 V. Special attention to tradeoffs between field generators utilizing IGBT circuits (HCMFG{sub 1}) and MOSFET circuits (HCMFG{sub 2}) was considered. The theory of operation, design, experimental results, and electronic setup are presented and analyzed.

  1. High-current operation of vertical-type organic transistor with preferentially oriented molecular film

    Science.gov (United States)

    Fukagawa, Hirohiko; Watanabe, Yasuyuki; Kudo, Kazuhiro; Nishida, Jun-ichi; Yamashita, Yoshiro; Fujikake, Hideo; Tokito, Shizuo; Yamamoto, Toshihiro

    2016-04-01

    A high-performance vertical-type organic transistor has been fabricated using bis(l,2,5-thiadiazolo)-p-quinobis(l,3-dithiole) (BTQBT) for the channel layer. The BTQBT molecules are oriented horizontally, with the molecular plane of each monolayer parallel to the substrate. The π-π stacking direction of the BTQBT molecules is aligned with the carrier transport direction in this vertical transistor. The modulated drain current density exceeded 1 A cm-2 upon the application of a gate voltage of less than 5 V. In addition, the device exhibits a high on/off current ratio of over 105.

  2. Preliminary Study into the Magnetically Assisted Blocking of Reverse Current in a Cold Cathode High Current Vacuum Switch

    National Research Council Canada - National Science Library

    Bower, S

    1999-01-01

    .... The design and build of a test switch was followed by a program of experimental work during which magnetic fields were applied to the switch to attempt to interrupt the current at the first zero...

  3. Both multiple-choice and short-answer quizzes enhance later exam performance in middle and high school classes.

    Science.gov (United States)

    McDermott, Kathleen B; Agarwal, Pooja K; D'Antonio, Laura; Roediger, Henry L; McDaniel, Mark A

    2014-03-01

    Practicing retrieval of recently studied information enhances the likelihood of the learner retrieving that information in the future. We examined whether short-answer and multiple-choice classroom quizzing could enhance retention of information on classroom exams taken for a grade. In seventh-grade science and high school history classes, students took intermittent quizzes (short-answer or multiple-choice, both with correct-answer feedback) on some information, whereas other information was not initially quizzed but received equivalent coverage in all other classroom activities. On the unit exams and on an end-of-semester exam, students performed better for information that had been quizzed than that not quizzed. An unanticipated and key finding is that the format of the quiz (multiple-choice or short-answer) did not need to match the format of the criterial test (e.g., unit exam) for this benefit to emerge. Further, intermittent quizzing cannot be attributed to intermittent reexposure to the target facts: A restudy condition produced less enhancement of later test performance than did quizzing with feedback. Frequent classroom quizzing with feedback improves student learning and retention, and multiple-choice quizzing is as effective as short-answer quizzing for this purpose. © 2013 American Psychological Association

  4. Current tobacco use among middle and high school students--United States, 2011.

    Science.gov (United States)

    2012-08-10

    Tobacco use continues to be the leading preventable cause of death and disease in the United States, with nearly 443,000 deaths occurring annually because of cigarette smoking and exposure to secondhand smoke. Moreover, nearly 90% of adult smokers begin smoking by age 18 years. To assess current tobacco use among youths, CDC analyzed data from the 2011 National Youth Tobacco Survey (NYTS). This report describes the results of that analysis, which indicated that, in 2011, the prevalence of current tobacco use among middle school and high school students was 7.1% and 23.2%, respectively, and the prevalence of current cigarette use was 4.3%, and 15.8%, respectively. During 2000-2011, among middle school students, a linear downward trend was observed in the prevalence of current tobacco use (14.9% to 7.1%), current combustible tobacco use (14.0% to 6.3%), and current cigarette use (10.7% to 4.3%). For high school students, a linear downward trend also was observed in these measures (current tobacco use [34.4% to 23.2%], current combustible tobacco use [33.1% to 21.0%], and current cigarette use [27.9% to 15.8%]). Interventions that are proven to prevent and reduce tobacco use among youths include media campaigns, limiting advertisements and other promotions, increasing the price of tobacco products, and reducing the availability of tobacco products for purchase by youths. These interventions should continue to be implemented as part of national comprehensive tobacco control programs and should be coordinated with Food and Drug Administration (FDA) regulations restricting the sale, distribution, and marketing of cigarettes and smokeless tobacco products to youths.

  5. Short poly(A) tails are a conserved feature of highly expressed genes.

    Science.gov (United States)

    Lima, Sarah Azoubel; Chipman, Laura B; Nicholson, Angela L; Chen, Ying-Hsin; Yee, Brian A; Yeo, Gene W; Coller, Jeff; Pasquinelli, Amy E

    2017-12-01

    Poly(A) tails are important elements in mRNA translation and stability, although recent genome-wide studies have concluded that poly(A) tail length is generally not associated with translational efficiency in nonembryonic cells. To investigate whether poly(A) tail size might be coupled to gene expression in an intact organism, we used an adapted TAIL-seq protocol to measure poly(A) tails in Caenorhabditis elegans. Surprisingly, we found that well-expressed transcripts contain relatively short, well-defined tails. This attribute appears to be dependent on translational efficiency, as transcripts enriched for optimal codons and ribosome association had the shortest tail sizes, whereas noncoding RNAs retained long tails. Across eukaryotes, short tails were a feature of abundant and well-translated mRNAs. This seems to contradict the dogma that deadenylation induces translational inhibition and mRNA decay and suggests that well-expressed mRNAs accumulate with pruned tails that accommodate a minimal number of poly(A)-binding proteins, which may be ideal for protective and translational functions.

  6. High current 66 kV tests on high stability PFN discharge capacitors for CERN LHC

    CERN Document Server

    Barnes, M J

    1999-01-01

    The European Laboratory for Particle Physics (CERN) is constructing a Large Hadron Collider (LHC) to be installed in an existing 27 km circumference tunnel. The LHC will be equipped with fast pulsed magnet systems for injecting two counter-rotating hadron beams. Two pulsed systems, of 4 magnets and 4 pulse forming networks (PFNs) each, are required for this purpose. TRIUMF will build and test 5 resonant charging power supplies (RCPS) and nine PFNs and the associated thyratron switch units as part of the Canadian contribution to CERN LHC. Failures in the PFN capacitors may lead to incorrect beam deflections that may in turn damage LHC components. For this reason the reliability of the capacitors must be exceptionally high. Hence sample PFN capacitors were purchased and tested. The test procedure included discharging the PFN capacitors from 66 kV, into a 10.1 Ohm resistance, for 500,000 cycles, at a frequency of approximately 1 Hz. Subsequently the PFN capacitors were discharged from 66 kV into a 2.7 Ohm resist...

  7. Low Overpotential and High Current CO2 Reduction with Surface Reconstructed Cu Foam Electrodess

    KAUST Repository

    Min, Shixiong

    2016-06-23

    While recent reports have demonstrated that oxide-derived Cu-based electrodes exhibit high selectivity for CO2 reduction at low overpotential, the low catalytic current density (<2 mA/cm2 at -0.45 V vs. RHE) still largely limits its applications for large-scale fuel synthesis. Here we report an extremely high current density for CO2 reduction at low overpotential using a Cu foam electrode prepared by air-oxidation and subsequent electroreduction. Apart from possessing three-dimensional (3D) open frameworks, the resulting Cu foam electrodes prepared at higher temperatures exhibit enhanced electrochemically active surface area and distinct surface structures. In particular, the Cu foam electrode prepared at 500 °C exhibits an extremely high geometric current density of ~9.4 mA/cm2 in CO2-satrurated 0.1 M KHCO3 aqueous solution and achieving ~39% CO and ~23% HCOOH Faradaic efficiencies at -0.45 V vs. RHE. The high activity and significant selectivity enhancement are attributable to the formation of abundant grain-boundary supported active sites and preferable (100) and (111) facets as a result of reconstruction of Cu surface facets. This work demonstrates that the structural integration of Cu foam with open 3D frameworks and the favorable surface structures is a promising strategy to develop an advanced Cu electrocatalyst that can operate at high current density and low overpotential for CO2 reduction.

  8. Development of large high current density superconducting solenoid magnets for use in high energy physics experiments. [Thesis

    Energy Technology Data Exchange (ETDEWEB)

    Green, M.A.

    1977-05-01

    The development of a unique type of large superconducting solenoid magnet, characterized by very high current density windings and a two-phase helium tubular cooling system is described. The development of the magnet's conceptual design and the construction of two test solenoids are described. The successful test of the superconducting coil and its tubular cooling refrigeration system is presented. The safety, environmental and economic impacts of the test program on future developments in high energy physics are shown. Large solid angle particle detectors for colliding beam physics will analyze both charged and neutral particles. In many cases, these detectors will require neutral particles, such as gamma rays, to pass through the magnet coil with minimum interaction. The magnet coils must be as thin as possible. The use of superconducting windings allows one to minimize radiation thickness, while at the same time maximizing charged particle momentum resolution and saving substantial quantities of electrical energy. The results of the experimental measurements show that large high current density solenoid magnets can be made to operate at high stored energies. The superconducting magnet development described has a positive safety and environmental impact. The use of large high current density thin superconducting solenoids has been proposed in two high energy physics experiments to be conducted at the Stanford Linear Accelerator Center and Cornell University as a result of the successful experiments described.

  9. Long-lived Ar-Hg plasma in the afterglow of a high-current pulsed discharge

    Energy Technology Data Exchange (ETDEWEB)

    Sergeichev, K. F.; Lukina, N. A.; Fesenko, A. A. [Russian Academy of Sciences, Prokhorov General Physics Institute (Russian Federation)

    2013-02-15

    High-density (n > 10{sup 12} cm{sup -3}) argon-mercury plasma produced by a short (t {approx} 20 {mu}s) high-power pulsed discharge in argon with an admixture of mercury vapor at a discharge current of {approx}50 A, an argon pressure of {approx}4 mm Hg, and a mercury vapor pressure of {approx}10{sup -3} mm Hg was studied using optical spectroscopy and radio physics methods. It is found that the lifetime of this plasma after the end of the discharge pulse is up to 10{sup -2} s. It is shown that such an abnormally long lifetime of such an afterglow plasma, as compared to the plasma of an argon discharge without an admixture of mercury vapor, is related to the long residence time of atoms and ions of both argon and mercury in highly excited states due to chemi-ionization processes involving long-lived metastable argon ions. It is suggested that dissociative recombination of highly excited molecular ions of argon play an important role in the transfer of excitation to argon atoms and ions that are close to autoionization states.

  10. Impacts of short-time scale water column variability on broadband high-frequency acoustic wave propagation

    Science.gov (United States)

    Eickmeier, Justin

    Acoustical oceanography is one way to study the ocean, its internal layers, boundaries and all processes occurring within using underwater acoustics. Acoustical sensing techniques allows for the measurement of ocean processes from within that logistically or financially preclude traditional in-situ measurements. Acoustic signals propagate as pressure wavefronts from a source to a receiver through an ocean medium with variable physical parameters. The water column physical parameters that change acoustic wave propagation in the ocean include temperature, salinity, current, surface roughness, seafloor bathymetry, and vertical stratification over variable time scales. The impacts of short-time scale water column variability on acoustic wave propagation include coherent and incoherent surface reflections, wavefront arrival time delay, focusing or defocusing of the intensity of acoustic beams and refraction of acoustic rays. This study focuses on high-frequency broadband acoustic waves, and examines the influence of short-time scale water column variability on broadband high-frequency acoustics, wavefronts, from 7 to 28 kHz, in shallow water. Short-time scale variability is on the order of seconds to hours and the short-spatial scale variability is on the order of few centimeters. Experimental results were collected during an acoustic experiment along 100 m isobaths and data analysis was conducted using available acoustic wave propagation models. Three main topics are studied to show that acoustic waves are viable as a remote sensing tool to measure oceanographic parameters in shallow water. First, coherent surface reflections forming striation patterns, from multipath receptions, through rough surface interaction of broadband acoustic signals with the dynamic sea surface are analyzed. Matched filtered results of received acoustic waves are compared with a ray tracing numerical model using a sea surface boundary generated from measured water wave spectra at the time of

  11. Structure of high latitude currents in global magnetospheric-ionospheric models

    Science.gov (United States)

    Wiltberger, M; Rigler, E. J.; Merkin, V; Lyon, J. G

    2016-01-01

    Using three resolutions of the Lyon-Fedder-Mobarry global magnetosphere-ionosphere model (LFM) and the Weimer 2005 empirical model we examine the structure of the high latitude field-aligned current patterns. Each resolution was run for the entire Whole Heliosphere Interval which contained two high speed solar wind streams and modest interplanetary magnetic field strengths. Average states of the field-aligned current (FAC) patterns for 8 interplanetary magnetic field clock angle directions are computed using data from these runs. Generally speaking the patterns obtained agree well with results obtained from the Weimer 2005 computing using the solar wind and IMF conditions that correspond to each bin. As the simulation resolution increases the currents become more intense and narrow. A machine learning analysis of the FAC patterns shows that the ratio of Region 1 (R1) to Region 2 (R2) currents decreases as the simulation resolution increases. This brings the simulation results into better agreement with observational predictions and the Weimer 2005 model results. The increase in R2 current strengths also results in the cross polar cap potential (CPCP) pattern being concentrated in higher latitudes. Current-voltage relationships between the R1 and CPCP are quite similar at the higher resolution indicating the simulation is converging on a common solution. We conclude that LFM simulations are capable of reproducing the statistical features of FAC patterns.

  12. Anodic Oxidation of Carbon Steel at High Current Densities and Investigation of Its Corrosion Behavior

    Science.gov (United States)

    Fattah-Alhosseini, Arash; Khan, Hamid Yazdani

    2017-06-01

    This work aims at studying the influence of high current densities on the anodization of carbon steel. Anodic protective coatings were prepared on carbon steel at current densities of 100, 125, and 150 A/dm2 followed by a final heat treatment. Coatings microstructures and morphologies were analyzed using X-ray diffraction (XRD) and scanning electron microscope (SEM). The corrosion resistance of the uncoated carbon steel substrate and the anodic coatings were evaluated in 3.5 wt pct NaCl solution through electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements. The results showed that the anodic oxide coatings which were prepared at higher current densities had thicker coatings as a result of a higher anodic forming voltage. Therefore, the anodized coatings showed better anti-corrosion properties compared to those obtained at lower current densities and the base metal.

  13. High-current relativistic klystron amplifier development for microsecond pulse lengths

    Science.gov (United States)

    Fazio, M. V.; Carlsten, B. E.; Faehl, R. J.; Kwan, T. J.; Rickel, D. G.; Stringfield, R. M.; Tallerico, P. J.

    1991-05-01

    Los Alamos is extending the performance of the Friedman-type, high-current relativistic klystron amplifier (RKA) to the microsecond regime while attempting to achieve the gigawatt-level peak power capability that has been characteristic of the RKA at shorter pulse lengths. Currently the electron beam power into the device is about 1 GW in microsecond duration pulses, with an effort underway to increase the beam power to 2.5 GW. To date the device has yielded an RF modulated electron beam power of 350 MW, with up to 50 MW coupled into the waveguide. Several aspects of RKA operation under investigation that affect RKA beam bunching efficiency and amplifier gain include cavity tuning, beam diameter, beam current, and input RF drive power, and the development of an output coupler that efficiently couples the microwave power from the low impedance beam into rectangular waveguide operating in the dominant mode. Current results from experimental testing and code modelling are presented.

  14. Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems

    DEFF Research Database (Denmark)

    Preindl, Matthias; Schaltz, Erik

    2010-01-01

    the use of a current controller which takes into account the discrete states of the inverter, e.g. DTC or a more modern approach: Model Predictive Direct Current Control (MPDCC). Moreover overshoots and oscillations in the speed are not desired in many applications, since they lead to mechanical stress......In drive systems the most used control structure is the cascade control with an inner torque, i.e. current and an outer speed control loop. The fairly small converter switching frequency in high power applications, e.g. wind turbines lead to modest speed control performance. An improvement bring...... behaviour. It compensates the load torque influence on the speed control setting a feed forward torque value, i.e. current reference value. The benefits are twice. The speed controller reaches immediately the speed reference value avoiding offsets which must be compensated by the weak integrator. Moreover...

  15. Ultra-Low Heat-Leak, High-Temperature Superconducting Current Leads for Space Applications

    Science.gov (United States)

    Rey, Christopher M.

    2013-01-01

    NASA Goddard Space Flight Center has a need for current leads used in an adiabatic demagnetization refrigerator (ADR) for space applications. These leads must comply with stringent requirements such as a heat leak of approximately 100 W or less while conducting up to 10 A of electric current, from more than 90 K down to 10 K. Additionally, a length constraint of leads was addressed by developing a superconducting hybrid lead. This hybrid lead comprises two different high-temperature superconducting (HTS) conductors bonded together at a thermally and electrically determined optimum point along the length of the current lead. By taking advantage of material properties of each conductor type, employing advanced fabrication techniques, and taking advantage of novel insulation materials, the company was able to develop and fabricate the lightweight, low heat-leak leads currently to NASA's specs.

  16. The differential Howland current source with high signal to noise ratio for bioimpedance measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jinzhen; Li, Gang; Lin, Ling, E-mail: linling@tju.edu.cn [State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, People' s Republic of China, and Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin University, Tianjin (China); Qiao, Xiaoyan [College of Physics and Electronic Engineering, Shanxi University, Shanxi (China); Wang, Mengjun [School of Information Engineering, Hebei University of Technology, Tianjin (China); Zhang, Weibo [Institute of Acupuncture and Moxibustion China Academy of Chinese Medical Sciences, Beijing (China)

    2014-05-15

    The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

  17. The differential Howland current source with high signal to noise ratio for bioimpedance measurement system

    Science.gov (United States)

    Liu, Jinzhen; Qiao, Xiaoyan; Wang, Mengjun; Zhang, Weibo; Li, Gang; Lin, Ling

    2014-05-01

    The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

  18. A CURRENT MIRROR BASED TWO STAGE CMOS CASCODE OP-AMP FOR HIGH FREQUENCY APPLICATION

    OpenAIRE

    RAMKRISHNA KUNDU; ABHISHEK PANDEY; SUBHRA CHAKRABORTY; VIJAY NATH

    2017-01-01

    This paper presents a low power, high slew rate, high gain, ultra wide band two stage CMOS cascode operational amplifier for radio frequency application. Current mirror based cascoding technique and pole zero cancelation technique is used to ameliorate the gain and enhance the unity gain bandwidth respectively, which is the novelty of the circuit. In cascading technique a common source transistor drive a common gate transistor. The cascoding is used to enhance the output resistance and hence ...

  19. Current status of free radicals and electronically excited metastable species as high energy propellants

    Science.gov (United States)

    Rosen, G.

    1973-01-01

    A survey is presented of free radicals and electronically excited metastable species as high energy propellants for rocket engines. Nascent or atomic forms of diatomic gases are considered free radicals as well as the highly reactive diatomic triatomic molecules that posess unpaired electrons. Manufacturing and storage problems are described, and a review of current experimental work related to the manufacture of atomic hydrogen propellants is presented.

  20. Alumni of High School Internship Program Return for 25th Anniversary to Inspire Current Students | Poster

    Science.gov (United States)

    The Building 549 auditorium is often packed with high school interns eager to hear a scientific lecture. On April 22, however, the room swelled with interns spanning a wider age range. At the 25th Werner H. Kirsten Student Intern Program (WHK SIP) Anniversary Symposium, incoming, current, and former interns gathered to celebrate the program, which has provided biomedical research experience for local high school seniors.

  1. Motion-induced eddy current thermography for high-speed inspection

    Directory of Open Access Journals (Sweden)

    Jianbo Wu

    2017-08-01

    Full Text Available This letter proposes a novel motion-induced eddy current based thermography (MIECT for high-speed inspection. In contrast to conventional eddy current thermography (ECT based on a time-varying magnetic field created by an AC coil, the motion-induced eddy current is induced by the relative motion between magnetic field and inspected objects. A rotating magnetic field created by three-phase windings is used to investigate the heating principle and feasibility of the proposed method. Firstly, based on Faraday’s law the distribution of MIEC is investigated, which is then validated by numerical simulation. Further, experimental studies are conducted to validate the proposed method by creating rotating magnetic fields at different speeds from 600 rpm to 6000 rpm, and it is verified that rotating speed will increase MIEC intensity and thereafter improve the heating efficiency. The conclusion can be preliminarily drawn that the proposed MIECT is a platform suitable for high-speed inspection.

  2. High-Speed Current dq PI Controller for Vector Controlled PMSM Drive

    Directory of Open Access Journals (Sweden)

    Mohammad Marufuzzaman

    2014-01-01

    Full Text Available High-speed current controller for vector controlled permanent magnet synchronous motor (PMSM is presented. The controller is developed based on modular design for faster calculation and uses fixed-point proportional-integral (PI method for improved accuracy. Current dq controller is usually implemented in digital signal processor (DSP based computer. However, DSP based solutions are reaching their physical limits, which are few microseconds. Besides, digital solutions suffer from high implementation cost. In this research, the overall controller is realizing in field programmable gate array (FPGA. FPGA implementation of the overall controlling algorithm will certainly trim down the execution time significantly to guarantee the steadiness of the motor. Agilent 16821A Logic Analyzer is employed to validate the result of the implemented design in FPGA. Experimental results indicate that the proposed current dq PI controller needs only 50 ns of execution time in 40 MHz clock, which is the lowest computational cycle for the era.

  3. High-speed current dq PI controller for vector controlled PMSM drive.

    Science.gov (United States)

    Marufuzzaman, Mohammad; Reaz, Mamun Bin Ibne; Rahman, Labonnah Farzana; Chang, Tae Gyu

    2014-01-01

    High-speed current controller for vector controlled permanent magnet synchronous motor (PMSM) is presented. The controller is developed based on modular design for faster calculation and uses fixed-point proportional-integral (PI) method for improved accuracy. Current dq controller is usually implemented in digital signal processor (DSP) based computer. However, DSP based solutions are reaching their physical limits, which are few microseconds. Besides, digital solutions suffer from high implementation cost. In this research, the overall controller is realizing in field programmable gate array (FPGA). FPGA implementation of the overall controlling algorithm will certainly trim down the execution time significantly to guarantee the steadiness of the motor. Agilent 16821A Logic Analyzer is employed to validate the result of the implemented design in FPGA. Experimental results indicate that the proposed current dq PI controller needs only 50 ns of execution time in 40 MHz clock, which is the lowest computational cycle for the era.

  4. Motion-induced eddy current thermography for high-speed inspection

    Science.gov (United States)

    Wu, Jianbo; Li, Kongjing; Tian, Guiyun; Zhu, Junzhen; Gao, Yunlai; Tang, Chaoqing; Chen, Xiaotian

    2017-08-01

    This letter proposes a novel motion-induced eddy current based thermography (MIECT) for high-speed inspection. In contrast to conventional eddy current thermography (ECT) based on a time-varying magnetic field created by an AC coil, the motion-induced eddy current is induced by the relative motion between magnetic field and inspected objects. A rotating magnetic field created by three-phase windings is used to investigate the heating principle and feasibility of the proposed method. Firstly, based on Faraday's law the distribution of MIEC is investigated, which is then validated by numerical simulation. Further, experimental studies are conducted to validate the proposed method by creating rotating magnetic fields at different speeds from 600 rpm to 6000 rpm, and it is verified that rotating speed will increase MIEC intensity and thereafter improve the heating efficiency. The conclusion can be preliminarily drawn that the proposed MIECT is a platform suitable for high-speed inspection.

  5. A filtering method to generate high quality short reads using illumina paired-end technology.

    Directory of Open Access Journals (Sweden)

    A Murat Eren

    Full Text Available Consensus between independent reads improves the accuracy of genome and transcriptome analyses, however lack of consensus between very similar sequences in metagenomic studies can and often does represent natural variation of biological significance. The common use of machine-assigned quality scores on next generation platforms does not necessarily correlate with accuracy. Here, we describe using the overlap of paired-end, short sequence reads to identify error-prone reads in marker gene analyses and their contribution to spurious OTUs following clustering analysis using QIIME. Our approach can also reduce error in shotgun sequencing data generated from libraries with small, tightly constrained insert sizes. The open-source implementation of this algorithm in Python programming language with user instructions can be obtained from https://github.com/meren/illumina-utils.

  6. Modelling of the forming devices of high-current pulsed accelerators

    Science.gov (United States)

    Averyanov, G. P.; Dmitrieva, V. V.; Kornev, N. P.

    2017-12-01

    The report provides a comparison of the mathematical model of the forming devices of high-current pulsed accelerators based on the solution of unsteady problems for electric circuits with the distributed parameters and the model implementing direct calculation methods obtained on the basis of operator transformations.

  7. High Order Voltage and Current Harmonic Mitigation Using the Modular Multilevel Converter STATCOM

    NARCIS (Netherlands)

    Kontos, E.; Tsolaridis, Georgios; Teodorescu, Remus; Bauer, P.

    2017-01-01

    Due to the increase of power electronic-based loads, the maintenance of high power quality poses a challenge in modern power systems. To limit the total harmonic distortion in the line voltage and currents at the point of the common coupling (PCC), active power filters are commonly employed. This

  8. Bilateral pelvic discontinuity: a unique condition characterized by high failure rates of current treatment

    Directory of Open Access Journals (Sweden)

    John R. Martin, MD

    2016-12-01

    Conclusions: Bilateral pelvic discontinuity is rare but presents the surgeon with a major reconstructive challenge. Only 1 patient went on to radiographic healing with current treatment strategies. Continued motion of the contralateral pelvic dissociation may account for the high failure rates. Surgeons should be aware of the challenges presented by this diagnosis and develop strategies to improve outcomes.

  9. High-Current Gain Two-Dimensional MoS 2 -Base Hot-Electron Transistors

    KAUST Repository

    Torres, Carlos M.

    2015-12-09

    The vertical transport of nonequilibrium charge carriers through semiconductor heterostructures has led to milestones in electronics with the development of the hot-electron transistor. Recently, significant advances have been made with atomically sharp heterostructures implementing various two-dimensional materials. Although graphene-base hot-electron transistors show great promise for electronic switching at high frequencies, they are limited by their low current gain. Here we show that, by choosing MoS2 and HfO2 for the filter barrier interface and using a noncrystalline semiconductor such as ITO for the collector, we can achieve an unprecedentedly high-current gain (α ∼ 0.95) in our hot-electron transistors operating at room temperature. Furthermore, the current gain can be tuned over 2 orders of magnitude with the collector-base voltage albeit this feature currently presents a drawback in the transistor performance metrics such as poor output resistance and poor intrinsic voltage gain. We anticipate our transistors will pave the way toward the realization of novel flexible 2D material-based high-density, low-energy, and high-frequency hot-carrier electronic applications. © 2015 American Chemical Society.

  10. Neutral current cross-section measurement at low 2 and high ...

    Indian Academy of Sciences (India)

    ... Public Lectures · Lecture Workshops · Refresher Courses · Symposia. Home; Journals; Pramana – Journal of Physics; Volume 79; Issue 5. Neutral current cross-section measurement at low 2 and high with the ZEUS detector at HERA. Prabhdeep Kaur on behalf of the ZEUS Collaboration. Poster Presentations Volume ...

  11. Graphitized Carbon Fibers as Multifunctional 3D Current Collectors for High Areal Capacity Li Anodes.

    Science.gov (United States)

    Zuo, Tong-Tong; Wu, Xiong-Wei; Yang, Chun-Peng; Yin, Ya-Xia; Ye, Huan; Li, Nian-Wu; Guo, Yu-Guo

    2017-08-01

    The Li metal anode has long been considered as one of the most ideal anodes due to its high energy density. However, safety concerns, low efficiency, and huge volume change are severe hurdles to the practical application of Li metal anodes, especially in the case of high areal capacity. Here it is shown that that graphitized carbon fibers (GCF) electrode can serve as a multifunctional 3D current collector to enhance the Li storage capacity. The GCF electrode can store a huge amount of Li via intercalation and electrodeposition reactions. The as-obtained anode can deliver an areal capacity as high as 8 mA h cm(-2) and exhibits no obvious dendritic formation. In addition, the enlarged surface area and porous framework of the GCF electrode result in lower local current density and mitigate high volume change during cycling. Thus, the Li composite anode displays low voltage hysteresis, high plating/stripping efficiency, and long lifespan. The multifunctional 3D current collector promisingly provides a new strategy for promoting the cycling lifespan of high areal capacity Li anodes. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. Electromagnetic Wave Excitation, Propagation, and Absorption in High Current Storage Rings

    Science.gov (United States)

    Novokhatski, A.; Seeman, J.; Sullivan, M.; Wienands, U.

    2016-04-01

    We analyze a variety of electromagnetic effects in storage rings with extremely high currents. Specifically, we discuss our experience in the operation of the PEP-II (SLAC B-factory). We present some outstanding and sometimes unpredictable effects of the behavior of electromagnetic waves excited by intense beams inside a vacuum chamber in storage rings. Although the impedance of the rings is usually designed to be small, intense high-current beams can still generate significant microwave power. This power can be enough to damage vacuum beam chamber elements, which may absorb electromagnetic waves. The most sensitive elements are RF seals, vacuum valves, shielded bellows, beam position monitor buttons, and ceramic tiles. Additionally, microwave heating leads to vacuum pressure spikes or even vacuum pressure instabilities that brings high detector background. Resonance excitation of the electromagnetic field may lead to a very high electric component amplitude that can cause breakdowns leading to sparks and discharges. Finally, high-power electromagnetic waves can be responsible for beam instabilities in the ring. Proper absorption of these generated waves may eliminate these effects. We feel our experience will be helpful in the design of new high current synchrotron light sources and storage rings.

  13. Dynamics of short eccentric plain seals with high axial Reynolds number. [for Space Shuttle engine hydrogen fuel turbopump

    Science.gov (United States)

    Allaire, P. E.; Lee, C. C.; Gunter, E. J.

    1978-01-01

    Plain seals with high axial flow rates produce large stiffness and damping coefficients that can help stabilize high-speed rotating machinery. When the shaft is eccentric in the seal, a Bernoulli effect low-pressure region occurs on the large-clearance side of the shaft. A fluid-restoring force tends to center the shaft and reduce vibrations. This work extends the previous theory for short plain centered seals to large eccentricities using a perturbation analysis. Surface roughness effects are also included. An analysis of seals used in the Space Shuttle main engine hydrogen fuel turbopump indicates the desirability of plain seals over the labyrinth type. Experimental results confirm this.

  14. The TITAN EBIT charge breeder for mass measurements on highly charged short-lived isotopes-First online operation

    Energy Technology Data Exchange (ETDEWEB)

    Lapierre, A., E-mail: lapierre@nscl.msu.ed [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); National Superconducting Laboratory (NSCL), Michigan State University, East Lansing, MI 48824 (United States); Brodeur, M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Brunner, T. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Physik Department E12, Technische Universitaet Muechen, James Franck Str., D-85748 Garching (Germany); Ettenauer, S.; Gallant, A.T. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada); Simon, V. [Max-Planck-Instituet fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Good, M. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Froese, M.W.; Crespo Lopez-Urrutia, J.R. [Max-Planck-Instituet fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Delheij, P. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Epp, S. [Max-Planck-Instituet fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Ringle, R.; Schwarz, S. [National Superconducting Laboratory (NSCL), Michigan State University, East Lansing, MI 48824 (United States); Ullrich, J. [Max-Planck-Instituet fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Dilling, J. [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC, V6T 2A3 (Canada); Department of Physics and Astronomy, University of British Columbia, Vancouver, BC, V6T 1Z1 (Canada)

    2010-12-01

    TITAN (TRIUMF's Ion Traps for Atomic and Nuclear science) is a novel online facility for high-precision mass measurements on short-lived isotopes. TITAN is the only such facility that employs an Electron-Beam Ion Trap (EBIT) charge-state breeder to produce highly charged ions for their use to increase the precision of mass measurements. We describe the recently commissioned TITAN EBIT and present the results of first injection, charge breeding, and extraction tests performed with stable and radioactive ions.

  15. Real-time computational camera system for high-sensitivity imaging by using combined long/short exposure

    Science.gov (United States)

    Sato, Satoshi; Okada, Yusuke; Azuma, Takeo

    2012-03-01

    In this study, we realize high-resolution (4K-format), small-size (1.43 x 1.43 μm pixel pitch size with a single imager) and high-sensitivity (four times higher sensitivity as compared to conventional imagers) video camera system. Our proposed system is the real time computational camera system that combined long exposure green pixels with short exposure red / blue pixels. We demonstrate that our proposed camera system is effective even in conditions of low illumination.

  16. HIGH-CURRENT COLD CATHODE FIELD EMISSION ARRAY FOR ELECTRON LENS APPLICATION

    Energy Technology Data Exchange (ETDEWEB)

    Hirshfield, Jay L

    2012-12-28

    During Phase I, the following goals were achieved: (1) design and fabrication of a novel, nano-dimensional CNT field emitter assembly for high current density application, with high durability; (2) fabrication of a ceramic based micro channel plate (MCP) and characterization of its secondary electron emission; and (3) characterizing the CNT/MCP cathode for high field emission and durability. As a result of these achievements, a relatively high current density of ~ 1.2 A/cm2 from a CNT cathode and single channel MCP were measured. The emission current was also extremely stable with a peak-to-peak variation of only 1.8%. The emission current could be further enhanced to meet requirements for electron lens applications by increasing the number of MCP channels. A calculation for maximum possible current density with a 1200 channel/cm2 MCP, placed over a cathode with 1200 uniformly functioning CNTs, would be ~1.46 kA/cm2, neglecting space charge limitations. Clearly this level of emission is far greater than what is needed for the electron lens application, but it does offer a highly comforting margin to account for sub-standard emitters and/or to allow the lesser challenge of building a cathode with fewer channels/cm2. A satisfactory goal for the electron lens application would be a controllable emission of 2-4 mA per channel in an ensemble of 800-1200 uniformly-functioning channels/cm2, and a cathode with overall area of about 1 cm2.

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

    Energy Technology Data Exchange (ETDEWEB)

    Litzenberger, Wayne; Lava, Val

    1994-08-01

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

  18. Investigating parasitic current formation in MITLs through high-order continuum kinetic simulations

    Science.gov (United States)

    Vogman, G. V.; Hammer, J. H.; Farmer, W. A.; Shumlak, U.

    2017-10-01

    The Z pulsed power facility is designed to deliver more than 20 MA of current to a load through magnetically insulated transmission lines (MITLs), which prevent high voltage arcs. Experimental results show that as much as 10% of the current can be lost due to the unintended formation of low-density plasmas in the MITLs. The configuration of the electric and magnetic fields within the MITL, where the plasma is born, creates conditions in which drift and kinetic instabilities can lead to the formation of parasitic currents. To understand the plasma dynamics that lead to current loss, the MITL configuration is investigated using a high-order continuum kinetic Vlasov-Poisson solver in two spatial and two velocity dimensions. The simulations capture the effects of varying magnetization and yield insights into plasma behavior over the course of current rise and corresponding magnetic field generation. The effects of plasma formation at the cathode versus at the anode are explored in detail. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  19. The high current, fast, 100ns, Linear Transformer Driver (LTD) developmental project at Sandia National Laboratories.

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Kevin S.; Long, Finis W.; Sinebryukhov, Vadim A. (High Current Electronic Institute (HCEI), Tomsk, Russia); Kim, Alexandre A. (High Current Electronic Institute (HCEI), Tomsk, RUSSIA); Wakeland, Peter Eric (Ktech Corporation, Albuquerque, NM); McKee, G. Randall; Woodworth, Joseph Ray; McDaniel, Dillon Heirman; Fowler, William E.; Mazarakis, Michael Gerrassimos; Porter, John Larry, Jr.; Struve, Kenneth William; Stygar, William A.; LeChien, Keith R.; Matzen, Maurice Keith

    2010-04-01

    Sandia National Laboratories, Albuquerque, N.M., USA, in collaboration with the High Current Electronic Institute (HCEI), Tomsk, Russia, is developing a new paradigm in pulsed power technology: the Linear Transformer Driver (LTD) technology. This technological approach can provide very compact devices that can deliver very fast high current and high voltage pulses straight out of the cavity with out any complicated pulse forming and pulse compression network. Through multistage inductively insulated voltage adders, the output pulse, increased in voltage amplitude, can be applied directly to the load. The load may be a vacuum electron diode, a z-pinch wire array, a gas puff, a liner, an isentropic compression load (ICE) to study material behavior under very high magnetic fields, or a fusion energy (IFE) target. This is because the output pulse rise time and width can be easily tailored to the specific application needs. In this paper we briefly summarize the developmental work done in Sandia and HCEI during the last few years, and describe our new MYKONOS Sandia High Current LTD Laboratory.

  20. High Current, Low Voltage Power Converter [20kA, 6V] LHC Converter Prototype

    CERN Document Server

    Jørgensen, H E; Dupaquier, A; Fernqvist, G

    1998-01-01

    The superconducting LHC accelerator requires high currents (~12.5kA) and relatively low voltages (~10 V) for its magnets. The need to install the power converters underground is the driving force for reduced volume and high efficiency. Moreover, the LHC machine will require a very high level of performance from the power converters, particularly in terms of DC stability, dynamic response and also in matters of EMC. To meet these requirements soft-switching techniques will be used. This paper describes the development of a [20kA,6V] power converter intended as a stable high-current source for D CCT calibration and an evaluation prototype for the future LHC converters. The converter is made with a modular concept with five current sources [4kA,6V] in parallel. The 4kA sources are built as plu g-in modules: a diode rectifier on the AC mains with a damped L-C passive filter, a Zero Voltage Switching inverter working at 20 kHz and an output stage (high frequency transformers, Schottky rectifi ers and output filter...

  1. Charge and fluence lifetime measurements of a dc high voltage GaAs photogun at high average current

    Directory of Open Access Journals (Sweden)

    J. Grames

    2011-04-01

    Full Text Available GaAs-based dc high voltage photoguns used at accelerators with extensive user programs must exhibit long photocathode operating lifetime. Achieving this goal represents a significant challenge for proposed high average current facilities that must operate at tens of milliamperes or more. This paper describes techniques to maintain good vacuum while delivering beam, and techniques that minimize the ill effects of ion bombardment, the dominant mechanism that reduces photocathode yield of a GaAs-based dc high voltage photogun. Experimental results presented here demonstrate enhanced lifetime at high beam currents by: (a operating with the drive laser beam positioned away from the electrostatic center of the photocathode, (b limiting the photocathode active area to eliminate photoemission from regions of the photocathode that do not support efficient beam delivery, (c using a large drive laser beam to distribute ion damage over a larger area, and (d by applying a relatively low bias voltage to the anode to repel ions created within the downstream beam line. A combination of these techniques provided the best total charge extracted lifetimes in excess of 1000 C at dc beam currents up to 9.5 mA, using green light illumination of bulk GaAs inside a 100 kV photogun.

  2. Charge and fluence lifetime measurements of a dc high voltage GaAs photogun at high average current

    Energy Technology Data Exchange (ETDEWEB)

    J. Grames, R. Suleiman, P.A. Adderley, J. Clark, J. Hansknecht, D. Machie, M. Poelker, M.L. Stutzman

    2011-04-01

    GaAs-based dc high voltage photoguns used at accelerators with extensive user programs must exhibit long photocathode operating lifetime. Achieving this goal represents a significant challenge for proposed high average current facilities that must operate at tens of milliamperes or more. This paper describes techniques to maintain good vacuum while delivering beam, and techniques that minimize the ill effects of ion bombardment, the dominant mechanism that reduces photocathode yield of a GaAs-based dc high voltage photogun. Experimental results presented here demonstrate enhanced lifetime at high beam currents by: (a) operating with the drive laser beam positioned away from the electrostatic center of the photocathode, (b) limiting the photocathode active area to eliminate photoemission from regions of the photocathode that do not support efficient beam delivery, (c) using a large drive laser beam to distribute ion damage over a larger area, and (d) by applying a relatively low bias voltage to the anode to repel ions created within the downstream beam line. A combination of these techniques provided the best total charge extracted lifetimes in excess of 1000 C at dc beam currents up to 9.5 mA, using green light illumination of bulk GaAs inside a 100 kV photogun.

  3. 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.

  4. High power density vertical-cavity surface-emitting lasers with ion implanted isolated current aperture.

    Science.gov (United States)

    Higuchi, Akira; Naito, Hideyuki; Torii, Kousuke; Miyamoto, Masahiro; Morita, Takenori; Maeda, Junya; Miyajima, Hirofumi; Yoshida, Harumasa

    2012-02-13

    We report on GaAs-based high power density vertical-cavity surface-emitting laser diodes (VCSELs) with ion implanted isolated current apertures. A continuous-wave output power of over 380 mW and the power density of 4.9 kW/cm2 have been achieved at 15 °C from the 100-μm-diameter aperture, which is the highest output characteristic ever reported for an ion implanted VCSEL. A high background suppression ratio of over 40 dB has also been obtained at the emission wavelength of 970 nm. The ion implantation technique provides an excellent current isolation in the apertures and would be a key to realize high power output from a VCSEL array.

  5. Small-Conductance Calcium-Activated Potassium Current Is Activated During Hypokalemia and Masks Short-Term Cardiac Memory Induced by Ventricular Pacing.

    Science.gov (United States)

    Chan, Yi-Hsin; Tsai, Wei-Chung; Ko, Jum-Suk; Yin, Dechun; Chang, Po-Cheng; Rubart, Michael; Weiss, James N; Everett, Thomas H; Lin, Shien-Fong; Chen, Peng-Sheng

    2015-10-13

    Hypokalemia increases the vulnerability to ventricular fibrillation. We hypothesize that the apamin-sensitive small-conductance calcium-activated potassium current (IKAS) is activated during hypokalemia and that IKAS blockade is proarrhythmic. Optical mapping was performed in 23 Langendorff-perfused rabbit ventricles with atrioventricular block and either right or left ventricular pacing during normokalemia or hypokalemia. Apamin prolonged the action potential duration (APD) measured to 80% repolarization (APD80) by 26 milliseconds (95% confidence interval [CI], 14-37) during normokalemia and by 54 milliseconds (95% CI, 40-68) during hypokalemia (P=0.01) at a 1000-millisecond pacing cycle length. In hypokalemic ventricles, apamin increased the maximal slope of APD restitution, the pacing cycle length threshold of APD alternans, the pacing cycle length for wave-break induction, and the area of spatially discordant APD alternans. Apamin significantly facilitated the induction of sustained ventricular fibrillation (from 3 of 9 hearts to 9 of 9 hearts; P=0.009). Short-term cardiac memory was assessed by the slope of APD80 versus activation time. The slope increased from 0.01 (95% CI, -0.09 to 0.12) at baseline to 0.34 (95% CI, 0.23-0.44) after apamin (Prabbit ventricular myocytes during hypokalemia (P=0.038). Hypokalemia activates IKAS to shorten APD and maintain repolarization reserve at late activation sites during ventricular pacing. IKAS blockade prominently lengthens the APD at late activation sites and facilitates ventricular fibrillation induction. © 2015 American Heart Association, Inc.

  6. Towards a 20 kA high temperature superconductor current lead module using REBCO tapes

    Science.gov (United States)

    Heller, R.; Bagrets, N.; Fietz, W. H.; Gröner, F.; Kienzler, A.; Lange, C.; Wolf, M. J.

    2018-01-01

    Most of the large fusion devices presently under construction or in operation consisting of superconducting magnets like EAST, Wendelstein 7-X (W7-X), JT-60SA, and ITER, use high temperature superconductor (HTS) current leads (CL) to reduce the cryogenic load and operational cost. In all cases, the 1st generation HTS material Bi-2223 is used which is embedded in a low-conductivity matrix of AgAu. In the meantime, industry worldwide concentrates on the production of the 2nd generation HTS REBCO material because of the better field performance in particular at higher temperature. As the new material can only be produced in a multilayer thin-film structure rather than as a multi-filamentary tape, the technology developed for Bi-2223-based current leads cannot be transferred directly to REBCO. Therefore, several laboratories are presently investigating the design of high current HTS current leads made of REBCO. Karlsruhe Institute of Technology is developing a 20 kA HTS current lead using brass-stabilized REBCO tapes—as a further development to the Bi-2223 design used in the JT-60SA current leads. The same copper heat exchanger module as in the 20 kA JT-60SA current lead will be used for simplicity, which will allow a comparison of the newly developed REBCO CL with the earlier produced and investigated CL for JT-60SA. The present paper discusses the design and accompanying test of single tape and stack REBCO mock-ups. Finally, the fabrication of the HTS module using REBCO stacks is described.

  7. Short- and Long-Term Validity of High School GPA for Admission to Colleges outside the United States

    Science.gov (United States)

    Al-Hattami, Abdulghani

    2014-01-01

    High school GPA is the only admission criterion that is currently used by many colleges in Yemen to select their potential students. Its predictive validity was investigated to ensure the accuracy of the admission decisions in these colleges. The relationship between students' persistence in the 4 years of college and high school GPA was studied…

  8. Polyatomic ions from a high current ion implanter driven by a liquid metal ion source.

    Science.gov (United States)

    Pilz, W; Laufer, P; Tajmar, M; Böttger, R; Bischoff, L

    2017-12-01

    High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi 2 + ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

  9. Application of High Harmonic Fast Waves to Off-Axis Current Drive in DIII-D

    Science.gov (United States)

    Prater, R.; Pinsker, R. I.; Moeller, C. P.; Porkolab, M.; Vdovin, V. L.

    2013-10-01

    High harmonic fast waves, also called ``whistlers'' or ``helicons,'' may be an effective means of driving current off-axis in high performance discharges in DIII-D. Modeling using the GENRAY ray tracing code APP shows that fast waves launched with frequency 500 MHz tend to spiral around the magnetic axis. If the electron beta is above 1.7%, the waves are damped around ρ = 0 . 5 for a broad range of conditions. The fast wave current drive in the test discharge is 2 to 4 times larger per MW than that from the electron cyclotron heating or neutral beam injection systems on DIII-D. Interestingly, the current drive location and magnitude are nearly independent of the launched n| | over the range 2 to 4. Use of a moderately large value, n| | = 3 , reduces the possibility of mode conversion to the slow wave. A traveling wave antenna is expected to be effective at launching the wave with a narrow spectrum of n| |, which also helps avoid mode conversion. A test of the physics of high harmonic fast wave current drive is planned for DIII-D. Work supported in part by the US Department of Energy under DE-FC02-04ER54698.

  10. Testing of a Shrouded, Short Mixing Stack Gas Eductor Model Using High Temperature Primary Flow.

    Science.gov (United States)

    1982-10-01

    problem but of less significance than the heated surfaces of shipboard structure. Various types of electronic equipments and sensors carried by a combatant...here was to validate current procedures by comparison with previous data it was not considered essential to rein- stall these sensors or duplicate...sec) 205 tABLE XIX Mixing Stack Temperatura Data, Model B Thermocouple Axial Mixing Stack Temperature _ mbjr Posii--- .. (I IF) . Uptake 180 850 950

  11. High Current Density InAsSb/GaSb Tunnel Field Effect Transistors

    OpenAIRE

    Dey, Anil; Borg, Mattias; Ganjipour, Bahram; Ek, Martin; Dick Thelander, Kimberly; Lind, Erik; Nilsson, Peter; Thelander, Claes; Wernersson, Lars-Erik

    2012-01-01

    Steep-slope devices, such as tunnel field-effect transistors (TFETs), have recently gained interest due to their potential for low power operation at room temperature. The devices are based on inter-band tunneling which could limit the on-current since the charge carriers must tunnel through a barrier to traverse the device. The InAs/GaSb heterostructure forms a broken type II band alignment which enables inter-band tunneling without a barrier, allowing high on-currents. We ha...

  12. High-Current GaSb/InAs(Sb) Nanowire Tunnel Field-Effect Transistors

    OpenAIRE

    Dey, Anil; Borg, Mattias; Ganjipour, Bahram; Ek, Martin; Dick Thelander, Kimberly; Lind, Erik; Thelander, Claes; Wernersson, Lars-Erik

    2013-01-01

    We present electrical characterization of GaSb/InAs(Sb) nanowire tunnel field-effect transistors. The broken band alignment of the GaSb/InAs(Sb) heterostructure is exploited to allow for interband tunneling without a barrier, leading to high ON-current levels. We report a maximum drive current of 310 μA/μm at Vds = 0.5 V. Devices with scaled gate oxides display transconductances up to gm = 250 mS/mm at Vds = 300 mV, which are normalized to the nanowire circumference at the axial heterojunction...

  13. Microstructural Degradation of Ni/YSZ Electrodes in Solid Oxide Electrolysis Cells under High Current

    DEFF Research Database (Denmark)

    Chen, Ming; Liu, Yi-Lin; Bentzen, Janet Jonna

    2013-01-01

    Ni/yttria stabilized zirconia (YSZ) supported solid oxide electrolysis cells (SOECs) were exposed to long-term galvanostatic electrolysis tests, under different testing conditions (temperature, gas composition, current density etc.) with an emphasis on high current density (above −1 A/cm2...... of Ni-YSZ interfacial reactions, taking place under the conditions prevailing under strong polarization. A mechanism for the formation of ZrO2 nano-particles on the Ni surface under the electrolysis cell testing is proposed and the possibility of Ni-YSZ interfacial reactions under such conditions (T, p...

  14. Full circuit calculation for electromagnetic pulse transmission in a high current facility

    OpenAIRE

    Wenkang Zou; Fan Guo; Lin Chen; Shengyi Song; Meng Wang; Weiping Xie; Jianjun Deng

    2014-01-01

    We describe herein for the first time a full circuit model for electromagnetic pulse transmission in the Primary Test Stand (PTS)—the first TW class pulsed power driver in China. The PTS is designed to generate 8–10 MA current into a z-pinch load in nearly 90 ns rise time for inertial confinement fusion and other high energy density physics research. The PTS facility has four conical magnetic insulation transmission lines, in which electron current loss exists during the establishment of magn...

  15. Short Latency Gray Matter Changes in Voxel-Based Morphometry following High Frequent Visual Stimulation.

    Science.gov (United States)

    Naegel, Steffen; Hagenacker, Tim; Theysohn, Nina; Diener, Hans-Christoph; Katsarava, Zaza; Obermann, Mark; Holle, Dagny

    2017-01-01

    Magnetic resonance imaging studies using voxel-based morphometry (VBM) detected structural changes in the human brain within periods of months or weeks. The underlying molecular mechanisms of VBM findings remain unresolved. We showed that simple visual stimulation by an alternating checkerboard leads to instant, short-lasting alterations of the primary and secondary visual cortex detected by VBM. The rapidness of occurrence (i.e., within 10 minutes) rather excludes most of the proposed physiological mechanism such as neural or glial cell genesis/degeneration or synapse turnover. We therefore favour cerebral fluid shifts to be the underlying correlate of the here observed VBM gray matter changes. Fast onset gray matter changes might be one important explanation for the inconsistency of VBM study results that often raise concern in regard to the validity of presented data. This study shows that changes detectable by VBM may occur within a few minutes after physiological stimulation and must be considered in future VBM experiments to avoid misinterpretation of results.

  16. Breakdown in helium in high-voltage open discharge with subnanosecond current front rise

    Energy Technology Data Exchange (ETDEWEB)

    Schweigert, I. V., E-mail: ischweig@itam.nsc.ru; Alexandrov, A. L. [Russian Academy of Sciences, Khristianovich Institute of Theoretical and Applied Mechanics, Siberian Branch (Russian Federation); Bokhan, P. A.; Zakrevskiy, Dm. E. [Russian Academy of Sciences, Rzhanov Institute of Semiconductors Physics, Siberian Branch (Russian Federation)

    2016-07-15

    Investigations of high-voltage open discharge in helium have shown a possibility of generation of current pulses with subnanosecond front rise, due to ultra-fast breakdown development. The open discharge is ignited between two planar cathodes with mesh anode in the middle between them. For gas pressure 6 Torr and 20 kV applied voltage, the rate of current rise reaches 500 A/(cm{sup 2} ns) for current density 200 A/cm{sup 2} and more. The time of breakdown development was measured for different helium pressures and a kinetic model of breakdown in open discharge is presented, based on elementary reactions for electrons, ions and fast atoms. The model also includes various cathode emission processes due to cathode bombardment by ions, fast atoms, electrons and photons of resonant radiation with Doppler shift of frequency. It is shown, that the dominating emission processes depend on the evolution of the discharge voltage during the breakdown. In the simulations, two cases of voltage behavior were considered: (i) the voltage is kept constant during the breakdown; (ii) the voltage is reduced with the growth of current. For the first case, the exponentially growing current is maintained due to photoemission by the resonant photons with Doppler-shifted frequency. For the second case, the dominating factor of current growth is the secondary electron emission. In both cases, the subnanosecond rise of discharge current was obtained. Also the effect of gas pressure on breakdown development was considered. It was found that for 20 Torr gas pressure the time of current rise decreases to 0.1 ns, which is in agreement with experimental data.

  17. Effect of Short-Term, High-Intensity Exercise on Anaerobic Threshold in Women.

    Science.gov (United States)

    Evans, Blanche W.

    This study investigated the effects of a six-week, high-intensity cycling program on anaerobic threshold (AT) in ten women. Subjects trained four days a week using high-intensity interval-type cycle exercises. Workouts included six 4-minute intervals cycling at 85 percent maximal oxygen uptake (VO sub 2 max), separated by 3-minute intervals of…

  18. Transient nanobubbles in short-time electrolysis

    NARCIS (Netherlands)

    Svetovoy, Vitaly; Sanders, Remco G.P.; Elwenspoek, Michael Curt

    2013-01-01

    Water electrolysis in a microsystem is observed and analyzed on a short-time scale of ∼10 μs. The very unusual properties of the process are stressed. An extremely high current density is observed because the process is not limited by the diffusion of electroactive species. The high current is

  19. A new method of rapid power measurement for MW-scale high-current particle beams

    Science.gov (United States)

    Xu, Yongjian; Hu, Chundong; Xie, Yuanlai; Liu, Zhimin; Xie, Yahong; Liu, Sheng; Liang, Lizheng; Jiang, Caichao; Sheng, Peng; Yu, Ling

    2015-09-01

    MW-scale high current particle beams are widely applied for plasma heating in the magnetic confinement fusion devices, in which beam power is an important indicator for efficient heating. Generally, power measurement of MW-scale high current particle beam adopts water flow calorimetry (WFC). Limited by the principles of WFC, the beam power given by WFC is an averaged value. In this article a new method of beam power for MW-scale high-current particle beams is introduced: (1) the temperature data of thermocouples embedded in the beam stopping elements were obtained using high data acquire system, (2) the surface heat flux of the beam stopping elements are calculated using heat transfer, (3) the relationships between positions and heat flux were acquired using numerical simulation, (4) the real-time power deposited on the beam stopping elements can be calculated using surface integral. The principle of measurement was described in detail and applied to the EAST neutral beam injector for demonstration. The result is compared with that measured by WFC. Comparison of the results shows good accuracy and applicability of this measuring method.

  20. Development of ultra-short high voltage pulse technology using magnetic pulse compression

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Byung Heon; Kim, S. G.; Nam, S. M.; Lee, B. C.; Lee, S. M.; Jeong, Y. U.; Cho, S. O.; Jin, J. T.; Choi, H. L

    1998-01-01

    The control circuit for high voltage switches, the saturable inductor for magnetic assist, and the magnetic pulse compression circuit were designed, constructed, and tested. The core materials of saturable inductors in magnetic pulse compression circuit were amorphous metal and ferrite and total compression stages were 3. By the test, in high repetition rate, high pulse compression were certified. As a result of this test, it became possible to increase life-time of thyratrons and to replace thyratrons by solid-state semiconductor switches. (author). 16 refs., 16 tabs.

  1. Numerical Simulation of Pulsation Flow in the Vapour Channel of Short Low Temperature Heat Pipes at High Heat Loads

    Science.gov (United States)

    Seryakov, A. V.; Konkin, A. V.

    2017-11-01

    The results of the numerical simulation of pulsations in the Laval-liked vapour channel of short low-temperature range heat pipes (HPs) are presented. The numerical results confirmed the experimentally obtained increase of the frequency of pulsations in the vapour channel of short HPs with increasing overheat of the porous evaporator relative to the boiling point of the working fluid. The occurrence of pressure pulsations inside the vapour channel in a short HPs is a complex phenomenon associated with the boiling beginning in the capillary-porous evaporator at high heat loads, and appearance the excess amount of vapour above it, leading to the increase in pressure P to a value at which the boiling point TB of the working fluid becomes higher than the evaporator temperature Tev. Vapour clot spreads through the vapour channel and condense, and then a rarefaction wave return from condenser in the evaporator, the boiling in which is resumed and the next cycle of the pulsations is repeated. Numerical simulation was performed using finite element method implemented in the commercial program ANSYS Multiphisics 14.5 in the two-dimensional setting of axis symmetric moist vapour flow with third kind boundary conditions.

  2. Efficacy of acute caffeine ingestion for short-term high-intensity exercise performance: a systematic review.

    Science.gov (United States)

    Astorino, Todd A; Roberson, Daniel W

    2010-01-01

    Caffeine is the most widely used drug in the world, commonly ingested in coffee, tea, soda, and energy drinks. Its ability to enhance muscular work has been apparent since the early 1900s. Caffeine typically increases endurance performance; however, efficacy of caffeine ingestion for short-term high-intensity exercise is equivocal, which may be explained by discrepancies in exercise protocols, dosing, and subjects' training status and habitual caffeine intake found across studies. The primary aim of this review is to critically examine studies that have tested caffeine's ability to augment performance during exercise dependent on nonoxidative metabolism such as sprinting, team sports, and resistance training. A review of the literature revealed 29 studies that measured alterations in short-term performance after caffeine ingestion. Each study was critically analyzed using the Physiotherapy Evidence Database (PEDro) scale. The mean PEDro score was 7.76 +/- 0.87. Eleven of 17 studies revealed significant improvements in team sports exercise and power-based sports with caffeine ingestion, yet these effects were more common in elite athletes who do not regularly ingest caffeine. Six of 11 studies revealed significant benefits of caffeine for resistance training. Some studies show decreased performance with caffeine ingestion when repeated bouts are completed. The exact mechanism explaining the ergogenic effect of caffeine for short-term exercise is unknown.

  3. High current density Esaki tunnel diodes based on GaSb-InAsSb heterostructure nanowires.

    Science.gov (United States)

    Ganjipour, Bahram; Dey, Anil W; Borg, B Mattias; Ek, Martin; Pistol, Mats-Erik; Dick, Kimberly A; Wernersson, Lars-Erik; Thelander, Claes

    2011-10-12

    We present electrical characterization of broken gap GaSb-InAsSb nanowire heterojunctions. Esaki diode characteristics with maximum reverse current of 1750 kA/cm(2) at 0.50 V, maximum peak current of 67 kA/cm(2) at 0.11 V, and peak-to-valley ratio (PVR) of 2.1 are obtained at room temperature. The reverse current density is comparable to that of state-of-the-art tunnel diodes based on heavily doped p-n junctions. However, the GaSb-InAsSb diodes investigated in this work do not rely on heavy doping, which permits studies of transport mechanisms in simple transistor structures processed with high-κ gate dielectrics and top-gates. Such processing results in devices with improved PVR (3.5) and stability of the electrical properties.

  4. CNTF inhibits high voltage activated Ca2+ currents in fetal mouse cortical neurones

    DEFF Research Database (Denmark)

    Holm, Ninna R; Christophersen, Palle; Hounsgaard, Jørn

    2002-01-01

    Neurotrophic factors yield neuroprotection by mechanisms that may be related to their effects as inhibitors of apoptosis as well as their effects on ion channels. The effect of ciliary neurotrophic factor (CNTF) on high-threshold voltage-activated Ca channels in cultured fetal mouse brain cortical...... neurones was investigated. Addition of CNTF into serum-free growth medium resulted in delayed reduction of the Ca2+ currents. The currents decreased to 50% after 4 h and stabilized at this level during incubation with CNTF for 48 h. Following removal of CNTF the inhibition was completely reversed after 18...... h. CNTF reduced the current of all pharmacological subtypes of Ca channels as shown by use of selective blockers of L, N, and P/Q type Ca channels (nifedipine, omega-conotoxin MVIIA, omega-agatoxin IVA). The Ca channel depression was mediated via the CNTF receptor, because enzymatic cleavage...

  5. Comparison of 2 Cathode Geometries for High Current (2 kA) Diodes

    CERN Document Server

    Pichoff, N

    2004-01-01

    AIRIX (FRANCE) and DARHT axis-1 (USA) are two high current accelerators designed for flash X-ray radiography. The electron beam produced (2 kA, 3.5 to 3.8 MV, 60 ns) is extracted from a velvet cold cathode. Specific calculations have demonstrated the influence of the cathode geometry on the emitted beam profile [1]. To check this assumption we have made two different experiments (DARHT March 2003 – AIRIX March 2004). We have compared the beam characteristics with two different geometries both theoretically and experimentally. The beam simulations have been done with 3 codes: a home-made code (M2V) and 2 commercial codes (PBGUNS and MAGIC). The extracted beam current and transverse profiles, for the first experiment, have been measured and compared to simulations results. In the second one, we have compared the beam’s extracted current and the energy spread.

  6. High current gain 4H-SiC bipolar junction transistor

    Science.gov (United States)

    Yourun, Zhang; Jinfei, Shi; Ying, Liu; Chengchun, Sun; Fei, Guo; Bo, Zhang

    2016-04-01

    A novel 4H-SiC BJT of high current gain with a suppressing surface traps effect has been proposed. It is effective to improve the current gain due to the lower electrons density in the surface region by extending the emitter metal to overlap the passivation layer on the extrinsic base surface. The electrons trapped in the extrinsic base surface induce the degeneration of SiC BJTs device performance. By modulating the electron recombination rate, the novel structure can increase the current gain to 63.2% compared with conventional ones with the compatible process technology. Optimized sizes are an overlapped metal length of 4 μm, as well as an oxide layer thickness of 50 nm. Project supported by the National Natural Science Foundation of China (Nos. 61306093, 61401075).

  7. Measurements and interpretations concerning leakage currents on polluted high voltage insulators

    Science.gov (United States)

    Thalassinakis, E.; Karagiannopoulos, C. G.

    2003-04-01

    This paper presents data that may aid physical interpretation of leakage currents on insulators suffering pollution under real physical conditions. The measurements were performed on the power distribution system on the island of Crete. An on-line recording system has been installed on the insulators of the 150 kV network, in order to monitor the leakage currents on the polluted insulators and investigate the various parameters of the phenomena. It is convincingly shown that in the timeframe of one period of 50 Hz, above a threshold voltage value (smaller than the peak voltage) a non-linear i-v relationship may develop, leading to bistability and non-linear conductance phenomena. The well-established theory regarding leakage currents on high voltage insulators, as well as that concerning dielectrics in strong electric fields, provide the required theoretical basis for the interpretation of the experimental results obtained.

  8. Recent beam-beam experience with multiple high current bunches in PEP-II

    Energy Technology Data Exchange (ETDEWEB)

    Minty, M.G.

    2000-02-07

    Operation with colliding beams at PEP-II has progressed remarkably well with over half the design specific luminosity and 5.2 x 10{sup 32}cm{sup {minus}2}s{sup {minus}1} in multiple bunches demonstrated during the last commissioning period before installation of the BABAR detector. Further luminosity increases are anticipated as the vertical beam size is reduced and beam currents are raised towards design values. At high currents interesting multibunch dynamics, which depend strongly on current distribution, have been observed during single-beam commissioning studies. Transverse beam instabilities nominally controlled using bunch-by-bunch feedback were observed to be significantly suppressed, in the absence of feedback, with beams in collision.

  9. Fast wave current drive at high ion cyclotron harmonics on DIII-D

    Energy Technology Data Exchange (ETDEWEB)

    Petty, C.C.; Grassie, J.S. de; Pinsker, R.I.; Prater, R. [General Atomics, San Diego, CA (United States); Baity, F.W. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Mau, T.K. [University of California, San Diego, La Jolla, CA (United States); Porkolab, M. [Massachusetts Institute of Technology, Cambridge, MA (United States)

    2001-12-01

    Current driven by the fast Alfven wave is measured at the fourth and eighth harmonics of the deuterium ion cyclotron frequency in identical plasmas on the DIII-D tokamak. In non-sawtoothing discharges with neutral beam injection heating, the radial profile of the fast wave current drive (FWCD) is determined by the response of the loop voltage profile to co- and counter-antenna phasings. The dimensionless current drive efficiency is a factor of two greater for the eighth harmonic case compared to the fourth harmonic case. Modelling of the fast wave absorption using a ray tracing code shows that the decrease in FWCD efficiency for the latter situation can be explained by high harmonic damping of the fast waves on energetic ions. (author)

  10. Microstructure characterisation of solid oxide electrolysis cells operated at high current density

    DEFF Research Database (Denmark)

    Bowen, Jacob R.; Bentzen, Janet Jonna; Chen, Ming

    High temperature solid oxide cells can be operated either as fuel cells or electrolysis cells for efficient power generation or production of hydrogen from steam or synthesis gas (H2 + CO) from steam and CO2 respectively. When operated under harsh conditions, they often exhibit microstructural......, microstructure evolution of the Ni-yttria stabilized zirconia (YSZ) is followed as a function of galvanostatic steam electrolysis testing at current densities between -0.5 and -1.0 A cm-2 for periods of up to 750 hours at 800 °C. The volume fraction and size of the percolating Ni particles was statistically...... quantified using the mean linear intercept method as a function of current density and correlated to increases in serial resistance. The above structural changes are then compared in terms of electrode degradation observed during the co-electrolysis of steam and CO2 at current densities up to -1.5 A cm-2...

  11. Soft switching (ZVZCS) high current, low voltage modular power converter (13 kA, 16 V)

    CERN Document Server

    Bordry, Frederick; Thiesen, H

    2001-01-01

    The Large Hadron Collider (LHC) is the next accelerator being constructed at the European Laboratory for Particle Physics (CERN). The superconducting LHC particle accelerator requires high currents (13 kA) and relatively low voltages (16 V) for its magnets. This paper describes the development and the production of a (13 kA, 16 V) power converter. The converter is made with a modular concept with five current sources (3.25 kA, 16 V) in parallel. The 3.25 kA sources are built as plug-in modules: a diode rectifier on the AC mains, a zero voltage zero current switching (ZVZCS) inverter working at 25 k Hz and an output stage. The obtained performance is presented and discussed. (6 refs).

  12. Short-Term Fates of High Sulfur Inputs in Northern California Vineyard Soils

    Energy Technology Data Exchange (ETDEWEB)

    E Hinckley; S Fendorf; P Matson

    2011-12-31

    The widespread application of elemental sulfur (S{sup 0}) to vineyards may have ecosystem effects at multiple scales. We evaluated the short-term fates of applied S{sup 0} in a Napa Valley vineyard; we determined changes in soil sulfur (S) speciation (measured by X-ray absorption near-edge structure (XANES) spectroscopy), soil pH, extractable sulfate (SO{sub 4}{sup 2-}), and total S to evaluate changes in acidity and soil S within the vineyard over time. Surface soil samples were collected immediately prior to and following two applications of S{sup 0} (6.7 kg S{sup 0} ha{sup -1}), with weekly collections in the 2 weeks between applications and following the last application. XANES spectra indicated that the majority of soil S persists in the +6 oxidation state and that S{sup 0} oxidizes within 7 days following application. Soil pH and extractable SO{sub 4}{sup 2-} measurements taken at 30 min after S{sup 0} application revealed generation of acidity and an increase in extractable SO{sub 4}{sup 2-}, but by 12 days after application, soil pH increased to approximately pre-application levels. These data suggest that the major consequence of reactive S applications in vineyards may be the accumulation of soil SO{sub 4}{sup 2-} and organic S during the growing season, which can be mobilized during storm events during the dormant (wet) season. In spatially-extensive winegrowing regions where these applications are made by hundreds of individual farmers each year, it will be important to understand the long-term implications of this perturbation to the regional S cycle.

  13. A Short Progress Report on High-Efficiency Perovskite Solar Cells.

    Science.gov (United States)

    Tang, He; He, Shengsheng; Peng, Chuangwei

    2017-12-01

    Faced with the increasingly serious energy and environmental crisis in the world nowadays, the development of renewable energy has attracted increasingly more attention of all countries. Solar energy as an abundant and cheap energy is one of the most promising renewable energy sources. While high-performance solar cells have been well developed in the last couple of decades, the high module cost largely hinders wide deployment of photovoltaic devices. In the last 10 years, this urgent demand for cost-effective solar cells greatly facilitates the research of solar cells. This paper reviews the recent development of cost-effective and high-efficient solar cell technologies. This report paper covers low-cost and high-efficiency perovskite solar cells. The development and the state-of-the-art results of perovskite solar cell technologies are also introduced.

  14. A Short Progress Report on High-Efficiency Perovskite Solar Cells

    Science.gov (United States)

    Tang, He; He, Shengsheng; Peng, Chuangwei

    2017-06-01

    Faced with the increasingly serious energy and environmental crisis in the world nowadays, the development of renewable energy has attracted increasingly more attention of all countries. Solar energy as an abundant and cheap energy is one of the most promising renewable energy sources. While high-performance solar cells have been well developed in the last couple of decades, the high module cost largely hinders wide deployment of photovoltaic devices. In the last 10 years, this urgent demand for cost-effective solar cells greatly facilitates the research of solar cells. This paper reviews the recent development of cost-effective and high-efficient solar cell technologies. This report paper covers low-cost and high-efficiency perovskite solar cells. The development and the state-of-the-art results of perovskite solar cell technologies are also introduced.

  15. New measurements of high-momentum nucleons and short-range structures in nuclei

    CERN Document Server

    Fomin, N; Asaturyan, R; Benmokhtar, F; Boeglin, W; Bosted, P; Bruell, A; Bukhari, M H S; Chudakov, E; Clasie, B; Connell, S H; Dalton, M M; Daniel, A; Day, D B; Dutta, D; Ent, R; Fassi, L El; Fenker, H; Filippone, B W; Garrow, K; Gaskell, D; Hill, C; Holt, R J; Horn, T; Jones, M K; Jourdan, J; Kalantarians, N; Keppel, C E; Kiselev, D; Kotulla, M; Lindgren, R; Lung, A F; Malace, S; Markowitz, P; McKee, P; Meekins, D G; Mkrtchyan, H; Navasardyan, T; Niculescu, G; Opper, A K; Perdrisat, C; Potterveld, D H; Punjabi, V; Qian, X; Reimer, P E; Roche, J; Rodriguez, V M; Rondon, O; Schulte, E; Seely, J; Segbefia, E; Slifer, K; Smith, G R; Solvignon, P; Tadevosyan, V; Tajima, S; Tang, L; Testa, G; Trojer, R; Tvaskis, V; Vulcan, W F; Wasko, C; Wesselmann, F R; Wood, S A; Wright, J; Zheng, X

    2011-01-01

    We present new, high-Q^2 measurements of inclusive electron scattering from high-momentum nucleons in nuclei. This yields an improved extraction of the strength of two-nucleon correlations for several nuclei, including light nuclei where clustering effects can, for the first time, be examined. The data extend to the kinematic regime where three-nucleon correlations are expected to dominate and we observe significantly greater strength in this region than previous measurements.

  16. A Short Progress Report on High-Efficiency Perovskite Solar Cells

    OpenAIRE

    Tang, He; He, Shengsheng; Peng, Chuangwei

    2017-01-01

    Faced with the increasingly serious energy and environmental crisis in the world nowadays, the development of renewable energy has attracted increasingly more attention of all countries. Solar energy as an abundant and cheap energy is one of the most promising renewable energy sources. While high-performance solar cells have been well developed in the last couple of decades, the high module cost largely hinders wide deployment of photovoltaic devices. In the last 10 years, this urgent demand ...

  17. High glucocorticoid receptor expression predicts short progression-free survival in ovarian cancer.

    Science.gov (United States)

    Veneris, Jennifer Taylor; Darcy, Kathleen M; Mhawech-Fauceglia, Paulette; Tian, Chunqiao; Lengyel, Ernst; Lastra, Ricardo R; Pejovic, Tanja; Conzen, Suzanne D; Fleming, Gini F

    2017-07-01

    To investigate the association of tumor glucocorticoid receptor (GR) expression and patient outcome in ovarian cancer. GR expression was evaluated by immunohistochemistry using tissue microarrays of specimens from 481 patients with ovarian cancer and 4 patients with benign conditions. Low GR expression was defined as an intensity of 0 or 1+ and high GR as 2+ or 3+ in >1% of tumor cells. Analyses were performed to evaluate the relationship of GR expression with clinical characteristics, progression-free survival (PFS) and overall survival (OS). GR protein was highly expressed in 133 of 341 (39.0%) tumors from patients who underwent upfront cytoreduction surgery followed by adjuvant chemotherapy. High GR expression was more common in serous tumors (p<0.001), high grade tumors (p<0.001), and advanced stage tumors (p=0.037). Median PFS was significantly decreased in cases with high GR (20.4months) compared to those with low GR (36.0months, HR=1.66, 95% CI 1.29-2.14, p<0.001). GR remained an independent prognostic factor for PFS in multivariate analysis. OS was not associated with GR status. These data suggest that high GR expression correlates with poor prognosis and support the hypothesis that modulating GR activity in combination with chemotherapy may improve outcomes. Copyright © 2017 Elsevier Inc. All rights reserved.

  18. Effect of high-voltage impulse current on the structure and function of rabbit heart

    Directory of Open Access Journals (Sweden)

    Xin-ping XU

    2011-06-01

    Full Text Available Objective To explore the effect of high-voltage impulse current(HVIC on the structure and function of rabbit heart.Methods Sixty healthy male rabbits were involved in present study and divided into 6 groups randomly(n=10.The rabbits were then shocked using a high-voltage pulse generator with current intensity of 0,50,100,150,250 and 500mA(pulse width 100μs,duration 5s respectively.The heart rate and electrocardiogram(ECG of rabbits were detected before and 0,1,3,7,14 and 28 days after the electric shock.Moreover,the myocardial tissue of rabbits was obtained immediately and 28 days after shock to observe the pathological changes.Results Immediately after electric shock of 50 to 500mA,the heart rate of rabbit increased by different degree,and the ECG showed arrhythmia,myocardial ischemia,atrial fibrillation and atrioventricular block,and the changes recovered gradually one day later.The pathological observation showed cell swelling,separation of myofibril and sarcoplasmic condensation of Purkinje fibers immediately after electric shock of 50 to 500mA,and the changes recovered 28 days after shock.The cardiac injuries aggravated with the increasing of current intensity,especially when it exceeded 150mA,and the recovery time prolonged.Conclusion High-voltage impulse current may induce recoverable injuries on heart structure and function,and the damage effect shows a correlation with the current intensity.

  19. Increased bone resorption and impaired bone microarchitecture in short-term and extended high-fat diet-induced obesity.

    Science.gov (United States)

    Patsch, Janina M; Kiefer, Florian W; Varga, Peter; Pail, Pamela; Rauner, Martina; Stupphann, Daniela; Resch, Heinrich; Moser, Doris; Zysset, Philippe K; Stulnig, Thomas M; Pietschmann, Peter

    2011-02-01

    Although obesity traditionally has been considered a condition of low risk for osteoporosis, this classic view has recently been questioned. The aim of this study was to assess bone microarchitecture and turnover in a mouse model of high-fat diet-induced obesity. Seven-week-old male C57BL/6J mice (n = 18) were randomized into 3 diet groups. One third (n = 6) received a low-fat diet for 24 weeks, one third was kept on an extended high-fat diet (eHF), and the remaining was switched from low-fat to high-fat chow 3 weeks before sacrifice (sHF). Serum levels of insulin, leptin, adiponectin, osteocalcin, and cross-linked telopeptides of type I collagen (CTX) were measured. In addition, bone microarchitecture was analyzed by micro-computed tomography; and lumbar spine bone density was assessed by dual-energy x-ray absorptiometry. The CTX, body weight, insulin, and leptin were significantly elevated in obese animals (sHF: +48%, +24%, +265%, and +102%; eHF: +43%, +52%, +761%, and +292%). The CTX, body weight, insulin, and leptin showed a negative correlation with bone density and bone volume. Interestingly, short-term high-fat chow caused similar bone loss as extended high-fat feeding. Bone volume was decreased by 12% in sHF and 19% in eHF. Bone mineral density was 25% (sHF) and 27% (eHF) lower when compared with control mice on low-fat diet. As assessed by the structure model index, bone microarchitecture changed from plate- to rod-like appearance upon high-fat challenge. Trabecular and cortical thickness remained unaffected. Short-term and extended high-fat diet-induced obesity caused significant bone loss in male C57BL/6J mice mainly because of resorptive changes in trabecular architecture. © 2011 Elsevier Inc. All rights reserved.

  20. Sharp burnout failure observed in high current-carrying double-walled carbon nanotube fibers

    Science.gov (United States)

    Song, Li; Toth, Geza; Wei, Jinquan; Liu, Zheng; Gao, Wei; Ci, Lijie; Vajtai, Robert; Endo, Morinobu; Ajayan, Pulickel M.

    2012-01-01

    We report on the current-carrying capability and the high-current-induced thermal burnout failure modes of 5-20 µm diameter double-walled carbon nanotube (DWNT) fibers made by an improved dry-spinning method. It is found that the electrical conductivity and maximum current-carrying capability for these DWNT fibers can reach up to 5.9 × 105 S m - 1 and over 1 × 105 A cm - 2 in air. In comparison, we observed that standard carbon fiber tended to be oxidized and burnt out into cheese-like morphology when the maximum current was reached, while DWNT fiber showed a much slower breakdown behavior due to the gradual burnout in individual nanotubes. The electron microscopy observations further confirmed that the failure process of DWNT fibers occurs at localized positions, and while the individual nanotubes burn they also get aligned due to local high temperature and electrostatic field. In addition a finite element model was constructed to gain better understanding of the failure behavior of DWNT fibers.