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Sample records for current experimental limits

  1. Current limiters

    Energy Technology Data Exchange (ETDEWEB)

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

    1996-09-01

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

  2. First experimental results with the Current Limit Avoidance System at the JET tokamak

    Energy Technology Data Exchange (ETDEWEB)

    De Tommasi, G. [Associazione EURATOM-ENEA-CREATE, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Galeani, S. [Dipartimento di Informatica, Sistemi e Produzione, Università di Roma, Tor Vergata, Rome (Italy); Jachmich, S. [Association EURATOM-Belgian State, Koninklijke Militaire School - Ecole Royale Militaire, B-1000 Brussels (Belgium); Joffrin, E. [IRFM-CEA, Centre de Cadarache, 13108 Saint-paul-lez-Durance (France); Lennholm, M. [EFDA Close Support Unit, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); European Commission, B-1049 Brussels (Belgium); Lomas, P.J. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Neto, A.C. [Associazione EURATOM-IST, Instituto de Plasmas e Fusao Nuclear, IST, 1049-001 Lisboa (Portugal); Maviglia, F. [Associazione EURATOM-ENEA-CREATE, Via Claudio 21, 80125 Napoli (Italy); McCullen, P. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Pironti, A. [Associazione EURATOM-ENEA-CREATE, Università di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Rimini, F.G. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Sips, A.C.C. [European Commission, B-1049 Brussels (Belgium); Varano, G.; Vitelli, R. [Dipartimento di Informatica, Sistemi e Produzione, Università di Roma, Tor Vergata, Rome (Italy); Zaccarian, L. [CNRS, LAAS, 7 Avenue du Colonel Roche, F-31400 Toulouse (France); Universitè de Toulouse, LAAS, F-31400 Toulouse (France)

    2013-06-15

    The Current Limit Avoidance System (CLA) has been recently deployed at the JET tokamak to avoid current saturations in the poloidal field (PF) coils when the eXtreme Shape Controller is used to control the plasma shape. In order to cope with the current saturation limits, the CLA exploits the redundancy of the PF coils system to automatically obtain almost the same plasma shape using a different combination of currents in the PF coils. In the presence of disturbances it tries to avoid the current saturations by relaxing the constraints on the plasma shape control. The CLA system has been successfully implemented on the JET tokamak and fully commissioned in 2011. This paper presents the first experimental results achieved in 2011–2012 during the restart and the ITER-like wall campaigns at JET.

  3. An experimental study on counter current flow limitation in annular narrow gaps with large diameter

    Energy Technology Data Exchange (ETDEWEB)

    Park, Rae Joon; Jeong, Ji Whan; Lee, Sung Jin; Cho, Young Ro; Ha, Kwang Sun; Kim, Sang Baik; Kim, Hee Dong [Korea Atomic Energy Research Institute, Taejeon (Korea)

    2002-04-01

    The present study intends to carry out CCFL experiment with the same gap size as the CHFG facility and suggest an empirical correlation in order to provide basic information useful to development of an empirical critical-power correlation. The present facility consists of water accumulator tank, test section, DC pump, air regulator, valves and sensors. Air and water are used as working fluids. The experiments are carried out at the atmospheric pressure. Differential pressure between the gap ends, liquid and gas phase flow rates, temperature, lower plenum pressure are measured.Measured values are expressed in terms of Wallis' parameter using gap size as a characteristic length. There is a big difference between the present experimental results and the Koizumi et al.'s results, but the present experimental results are very similar to the Richter et al.'s results. The present results agree well with the Osakabe and Kawasaki's results. In comparison of present experiments with the Koizumi et al.'s experiments, gap thickness is similar, but the diameter of the present is bigger than that of Koizumi et al.'s experiments. In comparison of present experiments with the Richter et al.'s experiments, diameter is similar, but the gap thickness of the present is smaller than that of Richter et al.'s experiments. It is judged from these results that correlation development on CCFL to consider gap thickness is reasonable at similar condition of diameter.The developed correlation will be used to develop the CHFG model. 36 refs., 26 figs., 7 tabs. (Author)

  4. Current limiter circuit system

    Energy Technology Data Exchange (ETDEWEB)

    Witcher, Joseph Brandon; Bredemann, Michael V.

    2017-09-05

    An apparatus comprising a steady state sensing circuit, a switching circuit, and a detection circuit. The steady state sensing circuit is connected to a first, a second and a third node. The first node is connected to a first device, the second node is connected to a second device, and the steady state sensing circuit causes a scaled current to flow at the third node. The scaled current is proportional to a voltage difference between the first and second node. The switching circuit limits an amount of current that flows between the first and second device. The detection circuit is connected to the third node and the switching circuit. The detection circuit monitors the scaled current at the third node and controls the switching circuit to limit the amount of the current that flows between the first and second device when the scaled current is greater than a desired level.

  5. Active inrush-current limiter

    Science.gov (United States)

    Kichak, R. A.

    1977-01-01

    By stretching turn-on time from approximately 1 to 200 ms, effects of inrush current (and of associated large current spikes) and current rate of rise (dl/dt) are made potentially less severe. Limiter arrangement consists of time-variable impedance connected in series between input dc power source return and power circuit of converter.

  6. Application of fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, A.

    2007-11-30

    This report presents the results of a study commissioned by the Department for Business, Enterprise and Industry (BERR; formerly the Department of Trade and Industry) into the application of fault current limiters in the UK. The study reviewed the current state of fault current limiter (FCL) technology and regulatory position in relation to all types of current limiters. It identified significant research and development work with respect to medium voltage FCLs and a move to high voltage. Appropriate FCL technologies being developed include: solid state breakers; superconducting FCLs (including superconducting transformers); magnetic FCLs; and active network controllers. Commercialisation of these products depends on successful field tests and experience, plus material development in the case of high temperature superconducting FCL technologies. The report describes FCL techniques, the current state of FCL technologies, practical applications and future outlook for FCL technologies, distribution fault level analysis and an outline methodology for assessing the materiality of the fault level problem. A roadmap is presented that provides an 'action agenda' to advance the fault level issues associated with low carbon networks.

  7. Fault current limiters using superconductors

    Science.gov (United States)

    Norris, W. T.; Power, A.

    Fault current limiters on power systems are to reduce damage by heating and electromechanical forces, to alleviate duty on switchgear used to clear the fault, and to mitigate disturbance to unfaulted parts of the system. A basic scheme involves a super-resistor which is a superconductor being driven to high resistance when fault current flows either when current is high during a cycle of a.c. or, if the temperature of the superconductive material rises, for the full cycle. Current may be commuted from superconductor to an impedance in parallel, thus reducing the energy dispersed at low temperature and saving refrigeration. In a super-shorted transformer the ambient temperature primary carries the power system current; the superconductive secondary goes to a resistive condition when excessive currents flow in the primary. A super-transformer has the advantage of not needing current leads from high temperature to low temperature; it behaves as a parallel super-resistor and inductor. The supertransductor with a superconductive d.c. bias winding is large and has small effect on the rate of fall of current at current zero; it does little to alleviate duty on switchgear but does reduce heating and electromechanical forces. It is fully active after a fault has been cleared. Other schemes depend on rapid recooling of the superconductor to achieve this.

  8. Superconducting fault current limiter for railway transport

    Energy Technology Data Exchange (ETDEWEB)

    Fisher, L. M., E-mail: LMFisher@niitfa.ru; Alferov, D. F.; Akhmetgareev, M. R.; Budovskii, A. I.; Evsin, D. V.; Voloshin, I. F.; Kalinov, A. V. [National Technical Physics and Automation Research Institute (Russian Federation)

    2015-12-15

    A resistive switching superconducting fault current limiter (SFCL) for DC networks with voltage of 3.5 kV and nominal current of 2 kA is developed. The SFCL consists of two series-connected units: block of superconducting modules and high-speed vacuum breaker with total disconnection time not more than 8 ms. The results of laboratory tests of superconducting SFCL modules in current limiting mode are presented. The recovery time of superconductivity is experimentally determined. The possibility of application of SFCL on traction substations of Russian Railways is considered.

  9. DC superconducting fault current limiter

    Science.gov (United States)

    Tixador, P.; Villard, C.; Cointe, Y.

    2006-03-01

    There is a lack of satisfying solutions for fault currents using conventional technologies, especially in DC networks, where a superconducting fault current limiter could play a very important part. DC networks bring a lot of advantages when compared to traditional AC ones, in particular within the context of the liberalization of the electric market. Under normal operation in a DC network, the losses in the superconducting element are nearly zero and only a small, i.e. a low cost, refrigeration system is then required. The absence of zero crossing of a DC fault current favourably accelerates the normal zone propagation. The very high current slope at the time of the short circuit in a DC grid is another favourable parameter. The material used for the experiments is YBCO deposited on Al2O3 as well as YBCO coated conductors. The DC limitation experiments are compared to AC ones at different frequencies (50-2000 Hz). Careful attention is paid to the quench homogenization, which is one of the key issues for an SC FCL. The University of Geneva has proposed constrictions. We have investigated an operating temperature higher than 77 K. As for YBCO bulk, an operation closer to the critical temperature brings a highly improved homogeneity in the electric field development. The material can then absorb large energies without degradation. We present tests at various temperatures. These promising results are to be confirmed over long lengths.

  10. High temperature superconducting fault current limiter

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL)

    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).

  11. Experimental Characterisation of the Interfacial Structure during Counter-Current Flow Limitation in a Model of the Hot Leg of a PWR

    Directory of Open Access Journals (Sweden)

    Christophe Vallée

    2012-01-01

    Full Text Available In order to investigate the two-phase flow behaviour during counter-current flow limitation in the hot leg of a pressurised water reactor, dedicated experiments were performed in a scaled down model of Kobe University. The experiments were performed with air and water at atmospheric pressure and room temperature. At high flow rates, CCFL occurs and the discharge of water to the reactor pressure vessel simulator is limited by the formation of slugs carrying liquid back to the steam generator. The structure of the interface was observed from the side of the channel test section using a high-speed video camera. An algorithm was developed to recognise the stratified interface in the camera frames after background subtraction. This method allows extracting the water level at any position in the image as well as performing further statistical treatments. The evolution of the interfacial structure along the horizontal part of the hot leg is shown by the visualisation of the probability distribution of the water level and analysed in function of the liquid and gas flow rates. The data achieved are useful for the analysis of the flow conditions as well as for the validation of modelling approaches like computational fluid dynamics.

  12. Fault current limiter using bulk oxides superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Belmont, O.; Ferracci, P.; Porcar, L.; Barbut, J.M. [Schneider Electric, Grenoble (France). Usine A3; Tixador, P.; Noudem, J.G.; Bourgault, D.; Tournier, R

    1998-08-01

    We study the limitation possibilities of bulk Bi high T{sub c} materials. For this we test these materials with AC or DC currents above their critical currents. We study particularly the evolution of the voltage with time or with current. The material, the value of the current and the time duration play important parts. For sintered Bi samples the voltage depends only on the current even for values much larger than the critical current. With textured samples the V(I) curves shows an hysteretic behaviour due to a warming up. The textured materials are more interesting than sintered ones in terms of required volume for the current limitation. In both cases the superconductors are in a dissipative state but not in the normal state. This state is nevertheless reached if the dissipated energy inside the sample is sufficient. We have tried to apply a magnetic field on the samples in order to trigger a more effective limitation. The voltage increases but with a limited effect for currents much higher (3-4 times) than the critical zero field current. We think that the dissipative state is due mainly to the grain boundaries which become resistive above the critical current. (orig.) 11 refs.

  13. NOAA NOS SOS, EXPERIMENTAL - Currents

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA NOS SOS server is part of the IOOS DIF SOS Project. The stations in this dataset have currents data. *These services are for testing and evaluation use...

  14. Current limiting remote power control module

    Science.gov (United States)

    Hopkins, Douglas C.

    1990-01-01

    The power source for the Space Station Freedom will be fully utilized nearly all of the time. As such, any loads on the system will need to operate within expected limits. Should any load draw an inordinate amount of power, the bus voltage for the system may sag and disrupt the operation of other loads. To protect the bus and loads some type of power interface between the bus and each load must be provided. This interface is most crucial when load faults occur. A possible system configuration is presented. The proposed interface is the Current Limiting Remote Power Controller (CL-RPC). Such an interface should provide the following power functions: limit overloading and resulting undervoltage; prevent catastrophic failure and still provide for redundancy management within the load; minimize cable heating; and provide accurate current measurement. A functional block diagram of the power processing stage of a CL-RPC is included. There are four functions that drive the circuit design: rate control of current; current sensing; the variable conductance switch (VCS) technology; and the algorithm used for current limiting. Each function is discussed separately.

  15. Top Quark Current Experimental Status

    CERN Document Server

    Juste, A

    2006-01-01

    Ten years after its discovery at the Tevatron collider, we still know little about the top quark. Its large mass suggests it may play a key role in the mechanism of Electroweak Symmetry Breaking (EWSB), or open a window of sensitivity to new physics related to EWSB and preferentially coupled to it. To determine whether this is the case, precision measurements of top quark properties are necessary. The high statistics samples being collected by the Tevatron experiments during Run II start to incisively probe the top quark sector. This report summarizes the experimental status of the top quark, focusing in particular on the recent measurements from the Tevatron.

  16. A New Curve Fitting Method for Forming Limit Experimental Data

    Institute of Scientific and Technical Information of China (English)

    Jieshi CHEN; Xianbin ZHOU

    2005-01-01

    The forming limit curve (FLC) can be obtained by. means of curve fitting the limit strain points of different strain paths. The theory of percent regression analysis is applied to the curve fitting of forming limit experimental data.Forecast intervals of FLC percentiles can be calculated. Thus reliability and confidence level can be considered. The theoretical method to get the limits of limit strain points distributing region is presented, and the FLC position can be adjusted according to practical requirement. Method for establishing FLC with high reliability using small samples is presented at the same time. This method can make full use of the current experimental data and the previous data.Compared with the traditional method that can only use current experimental data, fewer specimens are required in the present method to obtain the same precision and the result is more accurate with the same number of specimens.

  17. Superconducting Fault Current Limiter optimized design

    Energy Technology Data Exchange (ETDEWEB)

    Tixador, Pascal, E-mail: Pascal.Tixador@grenoble-inp.fr [Univ. Grenoble Alpes, G2Elab – Institut Néel, F-38000 Grenoble (France); CNRS, G2Elab – Institut Néel, F-38000 Grenoble (France); Badel, Arnaud [CNRS, G2Elab – Institut Néel, F-38000 Grenoble (France)

    2015-11-15

    Highlights: • A low cost design of YBCO Fault Current Limiter. • A high resistance conductor for reduced length. • An asymmetrical YBCO conductor (injection and AC losses). • A thickness suitable for non destructive hot spots. - Abstract: The SuperConducting Fault Current Limiter (SCFCL) appears as one of the most promising SC applications for the electrical grids. Despite its advantages and many successful field experiences the market of SCFCL has difficulties to take off even if the first orders for permanent operation in grids are taken. The analytical design of resistive SCFCL will be discussed with the objective to reduce the quantity of SC conductor (length and section) to be more cost-effective. For that the SC conductor must have a high resistivity in normal state. It can be achieved by using high resistivity alloy for shunt, such as Hastelloy®. One of the most severe constraint is that the SCFCL should operate safely for any faults, especially those with low prospective short-circuit currents. This constraint requires to properly design the thickness of the SC tape in order to limit the hot spot temperature. An operation at 65 K appears as very interesting since it decreases the SC cost at least by a factor 2 with a simple LN2 cryogenics. Taking into account the cost reduction in a near future, the SC conductor cost could be rather low, half a dollar per kV A.

  18. Novel 3-Phase Inductive Fault Current Limiter

    Science.gov (United States)

    Kosa, Janos

    The paper describes the inductive three-phase fault current limiter. In this work I examine the novel arrangements of the perfect closed superconducting loop made of HTS wire. I applied one iron core with 3 limbs and special loops for uniform temperature of the superconducting wire. In this work I present the results of my experiments with this device. I present the static and dynamic measured results of this solution. It has got several advantages e. g. fast switching and less fault power for high-power electric machines. The advantage of the equipment is that in the case of single-phase short circuit the current will decrease in all the three phases. This can be an appropriate solution for high power machines. For example, in the case of high-power electric motor if there is a single-phase breaking or a single phase short circuit, we can decrease the current in the three phases.

  19. Determining the Limiting Current Density of Vanadium Redox Flow Batteries

    Directory of Open Access Journals (Sweden)

    Jen-Yu Chen

    2014-09-01

    Full Text Available All-vanadium redox flow batteries (VRFBs are used as energy storage systems for intermittent renewable power sources. The performance of VRFBs depends on materials of key components and operating conditions, such as current density, electrolyte flow rate and electrolyte composition. Mass transfer overpotential is affected by the electrolyte flow rate and electrolyte composition, which is related to the limiting current density. In order to investigate the effect of operating conditions on mass transport overpotential, this study established a relationship between the limiting current density and operating conditions. First, electrolyte solutions with different states of charge were prepared and used for a single cell to obtain discharging polarization curves under various operating conditions. The experimental results were then analyzed and are discussed in this paper. Finally, this paper proposes a limiting current density as a function of operating conditions. The result helps predict the effect of operating condition on the cell performance in a mathematical model.

  20. Superconducting Fault Current Limiter optimized design

    Science.gov (United States)

    Tixador, Pascal; Badel, Arnaud

    2015-11-01

    The SuperConducting Fault Current Limiter (SCFCL) appears as one of the most promising SC applications for the electrical grids. Despite its advantages and many successful field experiences the market of SCFCL has difficulties to take off even if the first orders for permanent operation in grids are taken. The analytical design of resistive SCFCL will be discussed with the objective to reduce the quantity of SC conductor (length and section) to be more cost-effective. For that the SC conductor must have a high resistivity in normal state. It can be achieved by using high resistivity alloy for shunt, such as Hastelloy®. One of the most severe constraint is that the SCFCL should operate safely for any faults, especially those with low prospective short-circuit currents. This constraint requires to properly design the thickness of the SC tape in order to limit the hot spot temperature. An operation at 65 K appears as very interesting since it decreases the SC cost at least by a factor 2 with a simple LN2 cryogenics. Taking into account the cost reduction in a near future, the SC conductor cost could be rather low, half a dollar per kV A.

  1. Current limiting level-time characteristic of a superconducting fault current limiter

    Science.gov (United States)

    Tang, Y. J.; Yokomizu, Y.; Hayakawa, N.; Matsumura, T.; Okubo, H.; Kito, Y.

    A model superconducting fault current limiter (SE-FCL) has been developed. The adopted superconducting cable is composed of six strands insulated from each other. The current limiting level of the SC-FCL is measured under two types of overcurrent, a sinusoidal and an inrush current. The results show that the current limiting level of the SC-FCL Iq increases with an increase in the rate of rise of the overcurrent. By introducing a new parameter of time-to-quench tf, it is found that Iq increases with decreasing tf. This feature is taken as a current limiting level-time characteristic i.e. the Iq- tf characteristic. The existence of the Iq- tf characteristic found in the SC-FCL is qualitatively explained by measuring current distribution among the six strands. The superconducting cable is driven to the normal state strand by strand. Some delay in time is found from the quench of the first strand to that of the last and this is recognized as an Iq- tf characteristic in its current limiting performance.

  2. Experimental Realization of a Reflective Optical Limiter

    CERN Document Server

    Vella, Jarrett H; Browning, Andrew T; Limberopoulos, Nicholaos I; Vitebskiy, Ilya; Makri, Eleana; Kottos, Tsampikos

    2015-01-01

    Optical limiters transmit low-intensity light, while blocking laser radiation with excessively high intensity or fluence. A typical passive optical limiter absorbs most of the high level radiation, which can cause irreversible damage. In this communication we report the first experimental realization of a reflective optical limiter, which does not absorb the high-level laser radiation, but rather reflects it back to space. The design is based on a periodic layered structure composed of alternating SiO2 and Si3N4 layers with a single GaAs defect layer in the middle. At low intensities, the layered structure displays a strong resonant transmission via the localized defect mode. At high intensities, the two-photon absorption in the GaAs layer suppresses the localized mode along with the resonant transmission, the entire layered structure turns highly reflective within a broad frequency range covering the entire photonic band gap of the periodic layered structure. By contrast, a stand-alone GaAs layer would absor...

  3. Experimental Realization of a Reflective Optical Limiter

    Science.gov (United States)

    Vella, Jarrett H.; Goldsmith, John H.; Browning, Andrew T.; Limberopoulos, Nicholaos I.; Vitebskiy, Ilya; Makri, Eleana; Kottos, Tsampikos

    2016-06-01

    Optical limiters transmit low-intensity light, while blocking laser radiation with excessively high irradiance or fluence. A typical optical limiter involves a nonlinear material which is transparent at low light intensity and becomes opaque when the light intensity exceeds a certain level. Most of the high-level radiation is absorbed by the nonlinear material causing irreversible damage. This fundamental problem could be solved if the state of the nonlinear material changed from transparent to highly reflective (not absorptive) when the intensity becomes too high. None of the known nonlinear optical materials display such a property. A solution can be provided by a nonlinear photonic structure. In this communication, we report the experimental realization of a reflective optical limiter. The design is based on a planar microcavity composed of alternating SiO2 and Si3N4 layers with a single GaAs defect layer in the middle. At low intensity, the planar microcavity displays a strong resonant transmission via a cavity mode. As the intensity increases, two-photon absorption in GaAs kicks in, initially resulting in the microcavity-enhanced light absorption. A further increase in light intensity, though, suppresses the cavity mode along with the resonant transmission; the entire planar microcavity turns highly reflective within a broad frequency range covering the entire photonic band gap. This seemingly counterintuitive behavior is a general feature of resonant transmission via a cavity mode with purely nonlinear absorption.

  4. Inrush-Current Limiter And Bus Isolator

    Science.gov (United States)

    Dolland, Carlisle R.

    1994-01-01

    Electronic circuit protects electrical power bus and source of power against excessive current demands. Circuit intended for use with power-consuming electronic system drawing pulsed currents and including capacitor bank as low-impedance secondary source from which pulsed currents drawn.

  5. Medicare Current Beneficiary Survey - Limited Data Set

    Data.gov (United States)

    U.S. Department of Health & Human Services — The Medicare Current Beneficiary Survey (MCBS) is a continuous, multipurpose survey of a representative national sample of the Medicare population. There are two...

  6. Design Aspects and Test of an Inductive Fault Current Limiter

    Directory of Open Access Journals (Sweden)

    Arsénio Pedro

    2014-05-01

    Full Text Available Magnetic shielding inductive fault current limiters with high temperature superconducting tapes are considered as emerging devices that provide technology for the advent of modern power grids. The development of such limiters requires magnetic iron cores and leads to several design challenges regarding the constitutive parts of the limiter, namely the primary and secondary windings. Preliminary tests in a laboratory scale prototype have been carried out considering an assembly designed for simplicity in which the optimization of the magnetic coupling between the primary and secondary was not the main focus. This work addresses the design configuration of an inductive current limiter prototype regarding the assembly of the primary and secondary windings in the core. The prototype is based on a closed magnetic core wound by a primary, built from a normal electric conductor, and a short-circuited secondary, built from first generation superconducting tape. Four different design configurations are considered. Through experimental tests, the performance of such prototype is discussed and compared, in terms of normal and fault operation regimes. The results show that all the configurations assure effective magnetic shielding at normal operation regime, however, at fault operation regime, there are differences among configurations.

  7. Fault current limitation with HTc superconductors; Limitation de courant a partir de materiaux supraconducteurs HTc

    Energy Technology Data Exchange (ETDEWEB)

    Buzon, D.

    2002-09-15

    This report deals with the possibility of using high critical temperature (HTc) superconductors for current limitation. The transition from a superconductive to a high dissipative state could be used to limit inrush currents. This application of superconductivity is very attractive because it's an innovative device for electrical networks without any conventional equivalence at high voltage. This device would allow to improve the density of connections and the continuity of the electrical distribution. This study can be divided into two fields. The aim of the first one is to analyse the behaviour of different HTc superconductors for current limitation. We carried out experimental measurements to characterise those conductors during a nominal AC rating (measurements of losses) and during a fault setting. Particularly, a description of the transition in bulk textured YBCO samples near Tc was made of inhomogeneous transition of the device and to estimate its losses. Finally, a 1 kV / 100 A demonstrator made of 43 meanders of textured YBCO was tested at 90,5 K. Thermal gradients seem to be responsible of the altering of some of the samples. The other part of this study concerns the dynamic of the transition. Near Tc, our experiments showed that the transition is more homogeneous. Experimental measurements also showed the influence of thermal exchanges with the cryogenic surrounding on the transition. This point can be justified if the dissipated energy is locally concentrated. (author)

  8. CURRENT-VOLTAGE CURVES FOR TREATING EFFLUENT CONTAINING HEDP: DETERMINATION OF THE LIMITING CURRENT

    Directory of Open Access Journals (Sweden)

    T. Scarazzato

    2015-12-01

    Full Text Available Abstract Membrane separation techniques have been explored for treating industrial effluents to allow water reuse and component recovery. In an electrodialysis system, concentration polarization causes undesirable alterations in the ionic transportation mechanism. The graphic construction of the current voltage curve is proposed for establishing the value of the limiting current density applied to the cell. The aim of this work was to determine the limiting current density in an electrodialysis bench stack, the function of which was the treatment of an electroplating effluent containing HEDP. For this, a system with five compartments was used with a working solution simulating the rinse waters of HEDP-based baths. The results demonstrated correlation between the regions defined by theory and the experimental data.

  9. Imaging fast calcium currents beyond the limitations of electrode techniques.

    Science.gov (United States)

    Jaafari, Nadia; De Waard, Michel; Canepari, Marco

    2014-09-16

    The current understanding of Ca(2+) channel function is derived from the use of the patch-clamp technique. In particular, the measurement of fast cellular Ca(2+) currents is routinely achieved using whole-cell voltage-clamp recordings. However, this experimental approach is not applicable to the study of local native Ca(2+) channels during physiological changes of membrane potential in complex cells, since the voltage-clamp configuration constrains the membrane potential to a given value. Here, we report for the first time to our knowledge that Ca(2+) currents from individual cells can be quantitatively measured beyond the limitations of the voltage-clamp approach using fast Ca(2+) imaging with low-affinity indicators. The optical measurement of the Ca(2+) current was correlated with the membrane potential, simultaneously measured with a voltage-sensitive dye to investigate the activation of Ca(2+) channels along the apical dendrite of the CA1 hippocampal pyramidal neuron during the back-propagation of an action potential. To validate the method, we analyzed the voltage dependence of high- and low-voltage-gated Ca(2+) channels. In particular, we measured the Ca(2+) current component mediated by T-type channels, and we investigated the mechanisms of recovery from inactivation of these channels. This method is expected to become a reference approach to investigate Ca(2+) channels in their native physiological environment.

  10. Influence of Superconductor Fault Current Limiter on Transformers Lifetime

    Directory of Open Access Journals (Sweden)

    2012-07-01

    Full Text Available In this article the impact of the superconducting current limiter and reducing the incidenceof stress single phase short circuit has been analyzed with this method and conventionalmethod of current limiting resistance has been compared. For this purpose a saturated corehigh temperature superconducting current limiter model considered and its effects on networkperformance in different modes has been studied. PSCAD software for simulating thenetwork is used.

  11. Experimental Limit to Interstellar 244Pu Abundance

    CERN Document Server

    Paul, M; Ahmad, I; Berkovits, D; Bordeanu, C; Ghelberg, S; Hashimoto, Y; Hershcovitch, A I; Jiang, S; Nakanishi, T; Sakamoto, K

    2001-01-01

    Short-lived nuclides, now extinct in the solar system, are expected to be present in the interstellar medium (ISM). Grains of ISM origin were recently discovered in the inner solar system and at Earth orbit and may accrete onto Earth after ablation in the atmosphere. A favorable matrix for detection of such extraterrestrial material is presented by deep open-sea sediments with very low sedimentation rates (0.8-3 mm/kyr). We report here on the measurement of Pu isotopic abundances in a 1-kg deep-sea dry sediment collected in 1992 in the North Pacific. Our measured value of (3+-3)x10^5 244Pu atoms in the Pu-separated fraction of the sample shows no excess over the expected stratospheric nuclear fallout content and under reasonable assumptions we derive a limit of 2x10^-11 g-244Pu/g-ISM for the abundance of 244Pu in ISM.

  12. Natural Limits for Currents in Charge Separated Pulsar Magnetospheres

    CERN Document Server

    Jessner, A; Kunzl, T A

    2002-01-01

    Rough estimates and upper limits on current and particle densities form the basis of most of the canonical pulsar models. Whereas the surface of the rotating neutron star is capable of supplying sufficient charges to provide a current that, given the polar cap potential, could easily fuel the observed energy loss processes, observational and theoretical constraints provide strict upper limits to the charge densities. The space charge of a current consisting solely of particles having only one sign creates a compensating potential that will make the maximum current dependent on potential and distance. In the non-relativistic case this fact is expressed in the familiar Child-Langmuir law. Its relativistic generalization and subsequent application to the inner pulsar magnetosphere provides clear limits on the strength and radial extension of charged currents originating on the polar cap. Violent Pierce-type oscillations set in, if one attempts to inject more current than the space charge limit into a given volum...

  13. Limiting the current with HTc materials; HTc pour la limitation du courant

    Energy Technology Data Exchange (ETDEWEB)

    Barbut, J.M.; Belmont, O.; Devismes, M.F.; Noudem, J.G.; Porcar, L.; Sanchez, J. [Schneider Electric, Grenoble (France); Tixador, P. [CRTBT, CNRS, Grenoble (France); Bourgault, D.; Tournier, R. [Matformag, CNRS, Grenoble (France)

    1998-01-01

    Superconducting fault current limiter could be used in high voltage network. A most part of existing HTc superconducting materials have been tested in situation to limit fault current. Bulk materials are classified by growing critical current density which correspond to different behaviours. Critical electrical field during transition seems to be about 1 kV/m. (orig.). 7 refs.

  14. Vacuum Dielectric Recovery Characteristics of a Novel Current Limiting Circuit Breaker Base on Artificial Current Zero

    Institute of Scientific and Technical Information of China (English)

    JIANG Zhuangxian; ZHUANG Jinwu; WANG Chen; WU Jin; LIU Luhui

    2012-01-01

    A novel current limiting circuit breaker employs zero current switching method in cutting off DC current, which gives out a reverse impulsive current towards a high speed vacuum interrupter and force the current down to zero. This kind of breaker is simply in structure and can act in a very short time with high current limiting capability, and therefore it has a long electric life and is extremely suitable to be installed in a DC electrical system as a fault orotection utility.

  15. Space-charge limiting current in spherical cathode diodes

    Institute of Scientific and Technical Information of China (English)

    刘国治; 邵浩

    2003-01-01

    The results of the investigation on the space-charge limiting current for a spherical-cathode diode in the nonrelativistic situation are presented in this paper. The results show that the current enhancement factor equals the square of E-field enhancement factor on the cathode surface. The generated space-charge limiting current is deduced.In the case of a pin-shaped-cathode diode, the space-charge limiting current is also obtained, indicating that the current is independent of the geometric parameters of the diode. Analyses of the shielding effects and the conditions for generation of the uniform space-charge limiting beam show that, for pin-arrayed cathodes, the distance between pins should be in the range from 1.2D to 1.5D, where D is the distance between the two electrodes.

  16. Geometry dependence of 2-dimensional space-charge-limited currents

    CERN Document Server

    De Visschere, Patrick

    2016-01-01

    The space-charge-limited current in a zero thickness planar thin film depends on the geometry of the electrodes. We present a theory which is to a large extent analytical and applicable to many different lay-outs. We show that a space-charge-limited current can only be sustained if the emitting electrode induces a singularity in the field and if the singularity induced by the collecting electrode is not too strong. For those lay-outs where no space-charge-limited current can be sustained for a zero thickness film, the real thickness of the film must be taken into account using a numerical model.

  17. Fault Current Limitation with Superconducting YBCO Thin Films

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    The behavior of YBCO/metal bilayers under transport currents was explored in the framework of fault current limitation (FCL). Properties of the superconducting-normal transition were first studied phenomenologically during sweep current experiments. For current rates higher than 500 A/s, the transition into the normal state was based on non-thermal phenomena and was characterized by a flux creep regime ended by a jump into the normal state. At lower sweep rates, a total diversion of the current in the metallic shunt was observed for temperatures higher than 85 K. In this regime, a partial recovery of the superconducting state took place due to a finite thermal resistance between the superconductingand the metallic films. These two properties of partial diversion into the shunt and of fast switching for a quick rise of the current during a default were exploited for current limitation at 77 K. FCL experiments at 50 Hz show that YBCO/Au bilayers limit the current in about 1 ms at a valueof 2.5Ic by developing electrical fields as high as 3 kV/m. Moreover, a recovery of the zero resistance state could occur under rated mode. A straightforward application of this property would be the transformer connection. Finally, results on DC current limitation and recovery under nominal mode were presented for the first time.

  18. Injection-limited current in a polymeric heterojunction

    NARCIS (Netherlands)

    Woudenbergh, T. van; Wildeman, J.; Blom, P.W.M.; Mertens, RP; Claeys, CL

    2004-01-01

    This work describes the current over an interface between two different polymeric semiconductors. The interface barrier amounts to 0.7 to 1.0 eV, which is orders of magnitude larger than the thermal energy. It is demonstrated that the current across the interface is injection limited. Furthermore, i

  19. Testing of 3-meter Prototype Fault Current Limiting Cables

    Energy Technology Data Exchange (ETDEWEB)

    Gouge, Michael J [ORNL; Duckworth, Robert C [ORNL; Demko, Jonathan A [ORNL; Rey, Christopher M [ORNL; Thompson, James R [ORNL; Lindsay, David T [ORNL; Tolbert, Jerry Carlton [ORNL; Willen, Dag [Ultera; Lentge, Heidi [Ultera; Thidemann, Carsten [Ultera; Carter, Bill [AMSC

    2009-01-01

    Two 3-m long, single-phase cables have been fabricated by Ultera from second generation (2G) superconductor supplied by American Superconductor. The first cable was made with two layers of 2G tape conductor and had a critical current of 5,750 A while the second cable had four layers and a critical current of 8,500 A. AC loss was measured for both cables at ac currents of up to 4 kArms. Ultera performed initial fault current studies of both cables in Denmark with limited currents in the range from 9.1 to 44 kA. Results from these tests will provide a basis for a 25-m long, three-phase, prototype cable to be tested at ORNL early next year and a 300-m long, fault current limiting, superconducting cable to be installed in a ConEd substation in New York City.

  20. Using electric current to surpass the microstructure breakup limit

    Science.gov (United States)

    Qin, Rongshan

    2017-01-01

    The elongated droplets and grains can break up into smaller ones. This process is driven by the interfacial free energy minimization, which gives rise to a breakup limit. We demonstrated in this work that the breakup limit can be overpassed drastically by using electric current to interfere. Electric current free energy is dependent on the microstructure configuration. The breakup causes the electric current free energy to reduce in some cases. This compensates the increment of interfacial free energy during breaking up and enables the processing to achieve finer microstructure. With engineering practical electric current parameters, our calculation revealed a significant increment of the obtainable number of particles, showing electric current a powerful microstructure refinement technology. The calculation is validated by our experiments on the breakup of Fe3C-plates in Fe matrix. Furthermore, there is a parameter range that electric current can drive spherical particles to split into smaller ones.

  1. Thermal performance of back-up current-limiting fuses

    Energy Technology Data Exchange (ETDEWEB)

    Torres, E.; Mazon, A.J.; Fernandez, E.; Zamora, I. [Department of Electrical Engineering, University of the Basque Country (UPV/EHU), Alameda de Urquijo, s/n, Bilbao 48013, Bizkaia (Spain); Perez, J.C. [MESA - Schneider Electric, Gatica 48110 (Spain)

    2010-12-15

    The design and development of current-limiting power fuses requires considerable time and expense on testing to verify that the maximum temperature limits under the rated current established in international standards are not exceeded. This paper presents a new methodology that reproduces the thermal behaviour of high voltage current-limiting fuses under currents up to the rated value and so, it reduces the need for testing as prototypes, more similar to the final design, can be obtained. Firstly, the methodology solves the transient heating process of the fuse to obtain the values of the power dissipated and the heat transfer coefficient, corresponding to the steady state condition. Once these values have been calculated, the temperature distribution at the surface of the complete fuse is obtained. The validity of the method proposed has been verified by comparison of the numerical values calculated with those obtained by testing real fuses. (author)

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2003-07-01

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

  3. Fault current limiter with solid-state circuit breakers

    Science.gov (United States)

    Bălan, H.; Neamț, L.; Buzdugan, M. I.; Varodi, T.; Pop, E.

    2016-08-01

    Switching of power circuit breakers is an important technical issue, especially at short circuit, since the fault current cause thermal and dynamic stresses, and the power quality worsens. Recently, the development of distributed renewable electricity induces the short circuit protection problematic because the distributed production of electric energy cause the transport networks to lose their radial character and disturbs the protective relays coordination. The modern technologies for power switching uses static fault current limiters, which offers a viable solution to remove the problems caused by large fault currents in the system. An appropriate design of the current limiting device reduces the thermal and dynamic stress and limits the fault current to a low value. The static switches are based on high power semiconductor devices that offer advantages compared to mechanical switches. Using a fault current limiter that minimizes the effect of distributed generation of electricity in a radial network on the co-ordination of protective relays is a solution to this problem in terms of switching speed and lifespan of power switches.

  4. Current limitations and challenges in nanowaste detection, characterisation and monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Part, Florian; Zecha, Gudrun [Department of Water-Atmosphere-Environment, University of Natural Resources and Life Sciences, Institute of Waste Management, Muthgasse 107, 1190 Vienna (Austria); Causon, Tim [Department of Chemistry, Division of Analytical Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna (Austria); Sinner, Eva-Kathrin [Department of Nanobiotechnology, Institute for Synthetic Bioarchitectures, University of Natural Resources and Life Sciences, Muthgasse 11/II, 1190 Vienna (Austria); Huber-Humer, Marion, E-mail: marion.huber-humer@boku.ac.at [Department of Water-Atmosphere-Environment, University of Natural Resources and Life Sciences, Institute of Waste Management, Muthgasse 107, 1190 Vienna (Austria)

    2015-09-15

    Highlights: • First review on detection of nanomaterials in complex waste samples. • Focus on nanoparticles in solid, liquid and gaseous waste samples. • Summary of current applicable methods for nanowaste detection and characterisation. • Limitations and challenges of characterisation of nanoparticles in waste. - Abstract: Engineered nanomaterials (ENMs) are already extensively used in diverse consumer products. Along the life cycle of a nano-enabled product, ENMs can be released and subsequently accumulate in the environment. Material flow models also indicate that a variety of ENMs may accumulate in waste streams. Therefore, a new type of waste, so-called nanowaste, is generated when end-of-life ENMs and nano-enabled products are disposed of. In terms of the precautionary principle, environmental monitoring of end-of-life ENMs is crucial to allow assessment of the potential impact of nanowaste on our ecosystem. Trace analysis and quantification of nanoparticulate species is very challenging because of the variety of ENM types that are used in products and low concentrations of nanowaste expected in complex environmental media. In the framework of this paper, challenges in nanowaste characterisation and appropriate analytical techniques which can be applied to nanowaste analysis are summarised. Recent case studies focussing on the characterisation of ENMs in waste streams are discussed. Most studies aim to investigate the fate of nanowaste during incineration, particularly considering aerosol measurements; whereas, detailed studies focusing on the potential release of nanowaste during waste recycling processes are currently not available. In terms of suitable analytical methods, separation techniques coupled to spectrometry-based methods are promising tools to detect nanowaste and determine particle size distribution in liquid waste samples. Standardised leaching protocols can be applied to generate soluble fractions stemming from solid wastes, while

  5. SUSY effects in Rb: Revisited under current experimental constraints

    Science.gov (United States)

    Su, Wei; Yang, Jin Min

    2016-06-01

    In this note we revisit the SUSY effects in Rb under current experimental constraints including the LHC Higgs data, the B-physics measurements, the dark matter relic density and direct detection limits, as well as the precision electroweak data. We first perform a scan to figure out the currently allowed parameter space and then display the SUSY effects in Rb. We find that although the SUSY parameter space has been severely restrained by current experimental data, both the general MSSM and the natural-SUSY scenario can still alter Rb with a magnitude sizable enough to be observed at future Z-factories (ILC, CEPC, FCC-ee, Super Z-factory) which produce 109-1012Z-bosons. To be specific, assuming a precise measurement δRb = 2.0 ×10-5 at FCC-ee, we can probe a right-handed stop up to 530 GeV through chargino-stop loops, probe a sbottom to 850 GeV through neutralino-sbottom loops and a charged Higgs to 770 GeV through the Higgs-top quark loops for a large tan ⁡ β. The full one-loop SUSY correction to Rb can reach 1 ×10-4 in natural SUSY and 2 ×10-4 in the general MSSM.

  6. A current limiter with superconducting coil for magnetic field shielding

    Science.gov (United States)

    Kaiho, K.; Yamaguchi, H.; Arai, K.; Umeda, M.; Yamaguchi, M.; Kataoka, T.

    2001-05-01

    The magnetic shield type superconducting fault current limiter have been built and successfully tested in ABB corporate research and so on. The device is essentially a transformer in which the secondary winding is the superconducting tube. However, due to the large AC losses and brittleness of the superconducting bulk tube, they have not yet entered market. A current limiter with superconducting coil for the magnetic field shielding is considered. By using the superconducting coil made by the multi-filamentary high Tc superconductor instead of the superconducting bulk tube, the AC losses can be reduced due to the reduced superconductor thickness and the brittleness of the bulk tube can be avoidable. This paper presents a preliminary consideration of the magnetic shield type superconducting fault current limiter with superconducting coil as secondary winding and their AC losses in comparison to that of superconducting bulk in 50 Hz operation.

  7. Limiting current of intense electron beams in a decelerating gap

    Science.gov (United States)

    Nusinovich, G. S.; Beaudoin, B. L.; Thompson, C.; Karakkad, J. A.; Antonsen, T. M.

    2016-02-01

    For numerous applications, it is desirable to develop electron beam driven efficient sources of electromagnetic radiation that are capable of producing the required power at beam voltages as low as possible. This trend is limited by space charge effects that cause the reduction of electron kinetic energy and can lead to electron reflection. So far, this effect was analyzed for intense beams propagating in uniform metallic pipes. In the present study, the limiting currents of intense electron beams are analyzed for the case of beam propagation in the tubes with gaps. A general treatment is illustrated by an example evaluating the limiting current in a high-power, tunable 1-10 MHz inductive output tube (IOT), which is currently under development for ionospheric modification. Results of the analytical theory are compared to results of numerical simulations. The results obtained allow one to estimate the interaction efficiency of IOTs.

  8. Quantum theory of space charge limited current in solids

    Energy Technology Data Exchange (ETDEWEB)

    González, Gabriel, E-mail: gabriel.gonzalez@uaslp.mx [Cátedras Conacyt, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78000, Mexico and Coordinación para la Innovación y la Aplicación de la Ciencia y la Tecnología, Universidad Autónoma de San Luis Potosí, San Luis Potosí 78000 (Mexico)

    2015-02-28

    We present a quantum model of space charge limited current transport inside trap-free solids with planar geometry in the mean field approximation. We use a simple transformation which allows us to find the exact analytical solution for the steady state current case. We use our approach to find a Mott-Gurney like behavior and the mobility for single charge carriers in the quantum regime in solids.

  9. Superconducting fault-current limiter and inductor design

    Science.gov (United States)

    Rogers, J. D.; Boenig, H. J.; Chowdhuri, P.; Schermer, R. I.; Wollan, J. J.; Weldon, D. M.

    1982-11-01

    A superconducting fault current limiter (SFCL) that uses a biased superconducting inductor in a diode or thyristor bridge circuit was analyzed for transmission systems in 69, 138, and 230 rms kV utility transmission systems. The limiter was evaluated for costs with all components, superconducting coil, diode and/or SCR power electronics, high voltage insulation, high voltage bushings and vapor cooled leads, dewar, and refrigerator, included. A design was undertaken for the superconducting cable and coils for both diode and SCR 69 kV limiter circuits.

  10. Super conducting fault current limiter and inductor design

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.; Boenig, H.; Chowdhuri, P.; Schermer, R.; Weldon, D.; Wollan, J.

    1983-05-01

    A superconducting fault current limiter (SFCL) that uses a biased superconducting inductor in a diode or thyristor bridge circuit was analyzed for transmission systems in 69, 138, and 230 rms kV utility transmission systems. The limiter was evaluated for costs with all components--superconducting coil, diode and/or SCR power electronics, high voltage insulation, high voltage bushings and vapor cooled leads, dewar, and refrigerator--included. A design was undertaken for the superconducting cable and coils for both diode and SCR 69 kV limiter circuits.

  11. Superconducting fault-current limiter and inductor design

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, J.D.; Boenig, H.J.; Chowdhuri, P.; Schermer, R.I.; Wollan, J.J.; Weldon, D.M.

    1982-01-01

    A superconducting fault current limiter (SFCL) that uses a biased superconducting inductor in a diode or thyristor bridge circuit was analyzed for transmission systems in 69, 138, and 230 rms kV utility transmission systems. The limiter was evaluated for costs with all components - superconducting coil, diode and/or SCR power electronics, high voltage insulation, high voltage bushings and vapor cooled leads, dewar, and refrigerator - included. A design was undertaken for the superconducting cable and coils for both diode and SCR 69 kV limiter circuits.

  12. Cooling performance test of the superconducting fault current limiter

    Energy Technology Data Exchange (ETDEWEB)

    Yeom, H.; Hong, Y. J.; Ko, J.; In, S.; Kim, H. B.; Park, S. J. [Korea Institute ofMachinery and Materials, Daejeon (Korea, Republic of); Kim, H.; Kim, H. R. [Korea Electric Power Corporation Research Institute, Daejeon (Korea, Republic of)

    2014-12-15

    The superconducting fault current limiter (SFCL) is an electrical power system device that detects the fault current automatically and limits the magnitude of the current below a certain safety level. The SFCL module does not have any electrical resistance below the critical temperature, which facilitates lossless power transmission in the electric power system. Once given the fault current, however, the superconducting conductor exhibits extremely high electrical resistance, and the magnitude of the current is accordingly limited to a low value. Therefore, SFCL should be maintained at a temperature below the critical temperature, which justifies the cryogenic cooling system as a mandatory component. This report is a study which reported on the cooling system for the 154 kV-class hybrid SFCL owned by Korea Electric Power Corporation (KEPCO). Using the cryocooler, the temperature of liquid nitrogen (LN2) was lowered to 71 K. The cryostat was pressurized to 5 bars to improve the dielectric strength of nitrogen and suppress nitrogen bubble foaming during operation of SFCL. The SFCL module was immersed in the liquid nitrogen of the cryostat to maintain the superconducting state. The performance test results of the key components such as cryocooler, LN2 circulation pump, cold box, and pressure builder are shown in this paper.

  13. 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.

  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. Experimental estimation of entanglement at the quantum limit.

    Science.gov (United States)

    Brida, Giorgio; Degiovanni, Ivo Pietro; Florio, Angela; Genovese, Marco; Giorda, Paolo; Meda, Alice; Paris, Matteo G A; Shurupov, Alexander

    2010-03-12

    Entanglement is the central resource of quantum information processing and the precise characterization of entangled states is a crucial issue for the development of quantum technologies. This leads to the necessity of a precise, experimental feasible measure of entanglement. Nevertheless, such measurements are limited both from experimental uncertainties and intrinsic quantum bounds. Here we present an experiment where the amount of entanglement of a family of two-qubit mixed photon states is estimated with the ultimate precision allowed by quantum mechanics.

  16. Experimental limits from ATLAS on Standard Model Higgs production.

    CERN Multimedia

    ATLAS, collaboration

    2012-01-01

    Experimental limits from ATLAS on Standard Model Higgs production in the mass range 110-600 GeV. The solid curve reflects the observed experimental limits for the production of a Higgs of each possible mass value (horizontal axis). The region for which the solid curve dips below the horizontal line at the value of 1 is excluded with a 95% confidence level (CL). The dashed curve shows the expected limit in the absence of the Higgs boson, based on simulations. The green and yellow bands correspond (respectively) to 68%, and 95% confidence level regions from the expected limits. Higgs masses in the narrow range 123-130 GeV are the only masses not excluded at 95% CL

  17. LIMITATIONS OF CURRENT APPROACHES FOR THE TREATMENT OF ACROMEGALY.

    Science.gov (United States)

    Shanik, Michael H

    2016-02-01

    Acromegaly is a rare disease characterized by hypersecretion of growth hormone (GH), typically from a benign pituitary somatotroph adenoma, that leads to subsequent hypersecretion of insulin-like growth factor 1 (IGF-1). Patients with acromegaly have an increased risk of mortality and progressive worsening of comorbidities. Surgery, medical therapy, and radiotherapy are currently available treatment approaches for patients with acromegaly, with overall therapeutic goals of lowering GH levels and achieving normal IGF-1 levels, reducing tumor size, improving comorbidities, and minimizing mortality risk. Although surgery can lead to biochemical remission in some patients with acromegaly, many patients will continue to have uncontrolled disease and require additional treatment. We reviewed recently published reports and present a summary of the safety and efficacy of current treatment modalities for patients with acromegaly. A substantial proportion of patients who receive medical therapy or radiotherapy will have persistently elevated GH and/or IGF-1. Because of the serious health consequences of continued elevation of GH and IGF-1, there is a need to improve therapeutic approaches to optimize biochemical control, particularly in high-need patient populations for whom current treatment options provide limited benefit. This review discusses current treatment options for patients with acromegaly, limitations associated with each treatment approach, and areas within the current treatment algorithm, as well as patient populations for which improved therapeutic options are needed. Novel agents in development were also highlighted, which have the potential to improve management of patients with uncontrolled or persistent acromegaly.

  18. Defining the safe current limit for opening ID photon shutter

    Energy Technology Data Exchange (ETDEWEB)

    Seletskiy, S. [Brookhaven National Lab. (BNL), Upton, NY (United States). Photon Sciences Dept.

    2015-12-14

    The NSLS-II storage ring is protected from possible damage from insertion devices (IDs) synchrotron radiation by a dedicated active interlock system (AIS). It monitors electron beam position and angle and triggers beam drop if beam orbit exceeds the boundaries of pre-calculated active interlock envelope (AIE). The beamlines (BL) and beamline frontends (FE) are designed under assumption that the electron beam is interlocked within the AIE. For historic reasons the AIS engages the ID active interlock (AI-ID) at any non-zero beam current whenever the ID photon shutter (IDPS) is getting opened. Such arrangement creates major inconveniences for BLs commissioning. Apparently there is some IDPS safe current limit (SCL) under which the IDPS can be opened without interlocking the e-beam. The goal of this paper is to find such limit.

  19. Trapped-space-charge-limited currents in organics

    Energy Technology Data Exchange (ETDEWEB)

    Paasch, Gernot [IFW Dresden (Germany); Blom, Paul; Mandoc, Magda; Boer, Bert de [University of Groningen (Netherlands)

    2007-07-01

    The Mott-Gurney law for space charge limited current (SCLC) has been modified early to account for the presence of exponentially distributed traps. This expression has been widely used to analyse transport in organic light emitting diodes. However, the theory fails to describe the rather weak temperature dependence observed for electron transport, for instance in PPV derivatives. There we have shown that the trap-limited SCLC law is essentially modified if the density of transport states is of Gaussian type. Here, we discuss the origin of this modification and present a detailed analysis of the modified law. In addition, we derive further modifications for different combinations of densities of states of both the transport states and the trap distribution. As a result, rather different dependencies of the current on voltage, layer thickness and temperature are possible. Consequently, one has to exercise care in order to obtain reliable trap parameters from SCLC.

  20. Utility survey of requirements for a HTS fault current limiter

    DEFF Research Database (Denmark)

    Nielsen, Jan Nygaard; Jørgensen, P.; Østergaard, Jacob;

    2000-01-01

    The application of superconducting fault current limiters (SFCL) in the electric utility sector will clearly dependent on to what extent the needs and requirements of electric utilities can be met by the ongoing development of SFCL technology. This paper considers a questionnaire survey of which ...... needs and expectations the Danish electric utilities have to this new technology. A bus-tie application of SFCL in a distribution substation with three parallel-coupled transformers is discussed......The application of superconducting fault current limiters (SFCL) in the electric utility sector will clearly dependent on to what extent the needs and requirements of electric utilities can be met by the ongoing development of SFCL technology. This paper considers a questionnaire survey of which...

  1. Current self-limitation in a transverse nanosecond discharge with a slotted cathode

    Science.gov (United States)

    N, A. ASHURBEKOV; K, O. IMINOV; O, A. POPOV; G, S. SHAKHSINOV

    2017-03-01

    A high-voltage transverse pulsed nanosecond discharge with a slotted hollow cathode was found to be a source of high-energy (few kV) ribbon electron beams. Conditions for the formation and extinction of electron beams were experimentally studied in discharges in helium at pressures of 1–100 Torr. It was found that interaction of fast electrons with a non-uniform electric field near the slotted cathode led to limitation of the magnitude of the discharge current. A physical model was developed to describe the discharge current self-limitation that was in satisfactory agreement with the experimental results. Some technical solutions that are expected to increase the upper current limits in transverse nanosecond discharge are discussed.

  2. Superconducting fault current-limiter with variable shunt impedance

    Science.gov (United States)

    Llambes, Juan Carlos H; Xiong, Xuming

    2013-11-19

    A superconducting fault current-limiter is provided, including a superconducting element configured to resistively or inductively limit a fault current, and one or more variable-impedance shunts electrically coupled in parallel with the superconducting element. The variable-impedance shunt(s) is configured to present a first impedance during a superconducting state of the superconducting element and a second impedance during a normal resistive state of the superconducting element. The superconducting element transitions from the superconducting state to the normal resistive state responsive to the fault current, and responsive thereto, the variable-impedance shunt(s) transitions from the first to the second impedance. The second impedance of the variable-impedance shunt(s) is a lower impedance than the first impedance, which facilitates current flow through the variable-impedance shunt(s) during a recovery transition of the superconducting element from the normal resistive state to the superconducting state, and thus, facilitates recovery of the superconducting element under load.

  3. THE MATHEMATIC MODEL OF POTENTIAL RELAXATION IN COULOSTATIC CONDITIONS FOR LIMITING DIFFUSION CURRENT CASE

    Directory of Open Access Journals (Sweden)

    O. H. Kapitonov

    2010-05-01

    Full Text Available A mathematical model of coulostatic relaxation of the potential for solid metallic electrode was presented. The solution in the case of limiting diffusion current was obtained. On the basis of this model the technique of concentration measurements for heavy metal ions in diluted solutions was suggested. The model adequacy was proved by experimental data.

  4. Current Status and Research into Overcoming Limitations of Capsule Endoscopy.

    Science.gov (United States)

    Kwack, Won Gun; Lim, Yun Jeong

    2016-01-01

    Endoscopic investigation has a critical role in the diagnosis and treatment of gastrointestinal (GI) diseases. Since 2001, capsule endoscopy (CE) has been available for small-bowel exploration and is under continuous development. During the past decade, CE has achieved impressive improvements in areas such as miniaturization, resolution, and battery life. As a result, CE is currently a first-line tool for the investigation of the small bowel in obscure gastrointestinal bleeding and is a useful alternative to wired enteroscopy. Nevertheless, CE still has several limitations, such as incomplete examination and limited diagnostic and therapeutic capabilities. To resolve these problems, many groups have suggested several models (e.g., controlled CO2 insufflation system, magnetic navigation system, mobile robotic platform, tagging and biopsy equipment, and targeted drug-delivery system), which are in development. In the near future, new technological advances will improve the capabilities of CE and broaden its spectrum of applications not only for the small bowel but also for the colon, stomach, and esophagus. The purpose of this review is to introduce the current status of CE and to review the ongoing development of solutions to address its limitations.

  5. Correcting Acidosis during Hemodialysis: Current Limitations and a Potential Solution.

    Science.gov (United States)

    Tovbin, David; Sherman, Richard A

    2016-01-01

    The deleterious catabolic and pro-inflammatory effects of acidosis in hemodialysis (HD) patients and the importance of its correction for limiting mineral bone disease (MBD) are well known. Although oral base therapy could be a solution for correcting acidosis in HD patients, it increases their already enormous medication load and sodium intake; this approach is not used commonly. Therefore, we need to rely more on correcting acidosis during the HD procedure, which is difficult to achieve, in part, because HD is an intermittent therapy. The currently used fixed dialysate bicarbonate concentrations are associated with pre-HD acidosis and intra-dialytic alkalosis. We suggest that a decreasing dialysate bicarbonate concentration from an initially high concentration be considered as a means of correcting acidosis with limited intra-dialytic alkalosis. Some evidence, as well as theoretical considerations, supports such an approach. © 2015 Wiley Periodicals, Inc.

  6. Pediatric minimally invasive surgery in Africa: limitations and current situation.

    Science.gov (United States)

    Loveland, Jerome; Numanoglu, Alp; Hay, Sameh Abdel

    2012-05-01

    The second largest and most populous continent, with an exploding pediatric population, Africa has an overwhelming burden on its very limited pediatric surgical services. In an international environment of progressively advancing endoscopic and robotic surgical techniques, the authors focus on the current role of endoscopic surgery on the continent and explore the potential reasons for its delayed acceptance and implementation. They proceed to document the spectrum of what is available and, using their "African experience," expand on financially viable models of further rolling out these techniques, including discussion around suitable training models for surgeons and their teams. Copyright © 2012 Elsevier Inc. All rights reserved.

  7. Proposed hybrid superconducting fault current limiter for distribution systems

    Energy Technology Data Exchange (ETDEWEB)

    Elmitwally, A. [Elect. Eng. Dept., Mansoura University, Mansoura 35516 (Egypt)

    2009-11-15

    In this paper, a new hybrid fault current limiter is proposed for primary distribution systems. It incorporates a high temperature superconducting element in parallel with other two branches. The first is an inductive impedance to share the fault current with. The second branch is a gate-turn-off thyristor switch controlled to work in either of two modes. For the main mode, it controls the temperature of the superconducting element and protect it against damaging excessive heating. Instead, it keeps the device applicable without that superconducting element in the auxiliary operation mode. The design, control and operation of the device is addressed. Its performance in 11 kV distribution systems with DG is investigated. The factors affecting the device behavior for different scenarios are explored. (author)

  8. Potential and limitations of eddy current lockin-thermography

    Science.gov (United States)

    Riegert, G.; Gleiter, A.; Busse, G.

    2006-04-01

    Eddy current thermography uses an induction coil to induce eddy currents in conductive materials. The involved resistive losses heat the sample. By modulation of the eddy current amplitude, thermal waves are generated which interact with boundaries thereby revealing defects. Conventional eddy current testing has only a limited depth range due to the skin effect of metal samples. In Induction-Lockin-Thermography (ILT) the depth range is extended by the thermal penetration depth. An infrared camera monitors the modulation of the temperature field on the surface as a response to the coded excitation thereby allowing for fast imaging of defects in larger areas without the need of slow point-by-point mapping. This response is decoded by a Fourier analysis at the modulation frequency. So the extracted information is displayed by just two images where one displays local amplitude and the other local phase. ILT has significant advantages as compared to inductive heating with visual inspection of the thermographic sequence: Phase angle images are independent of most artifacts like reflections, variation in emission coefficient, or inhomogeneous heating. Due to the performed Fourier analysis of the temperature image sequence, the signal-to-noise ratio in the amplitude and phase images is significantly better than in single temperature images of the sequence. Induction heating is confined to conductive materials. However, it is applicable not only to metals but also to carbon fiber reinforced laminates (CFRP) or carbon fiber reinforced ceramics (C/C-SiC). The presented examples for applications of ILT illustrate the potential and limitations of this new non-destructive inspection method.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-04-01

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

  10. Experimental Study of Explosion Limits of Refrigerants and Lubricants’ Mixture

    OpenAIRE

    Shi, Y.Q.; Chen, Guangming; Chen, Q.

    2012-01-01

    The explosion limits of refrigerants and lubricants’ mixture were studied. The refrigerants like R161, R1234yf and R152a are combustible. Lubricants, to a certain extent, are combustion-supporting. In many actual conditions, lubricants and refrigerants are mixed together. In this paper, a test device which can be run automatically was established according to ASTM E681-09, and the explosive experimental of refrigerants and lubricants’ mixture in some ratio was studied. By altering the proport...

  11. Ion current rectification, limiting and overlimiting conductances in nanopores.

    Directory of Open Access Journals (Sweden)

    Liesbeth van Oeffelen

    Full Text Available Previous reports on Poisson-Nernst-Planck (PNP simulations of solid-state nanopores have focused on steady state behaviour under simplified boundary conditions. These are Neumann boundary conditions for the voltage at the pore walls, and in some cases also Donnan equilibrium boundary conditions for concentrations and voltages at both entrances of the nanopore. In this paper, we report time-dependent and steady state PNP simulations under less restrictive boundary conditions, including Neumann boundary conditions applied throughout the membrane relatively far away from the nanopore. We simulated ion currents through cylindrical and conical nanopores with several surface charge configurations, studying the spatial and temporal dependence of the currents contributed by each ion species. This revealed that, due to slow co-diffusion of oppositely charged ions, steady state is generally not reached in simulations or in practice. Furthermore, it is shown that ion concentration polarization is responsible for the observed limiting conductances and ion current rectification in nanopores with asymmetric surface charges or shapes. Hence, after more than a decade of collective research attempting to understand the nature of ion current rectification in solid-state nanopores, a relatively intuitive model is retrieved. Moreover, we measured and simulated current-voltage characteristics of rectifying silicon nitride nanopores presenting overlimiting conductances. The similarity between measurement and simulation shows that overlimiting conductances can result from the increased conductance of the electric double-layer at the membrane surface at the depletion side due to voltage-induced polarization charges. The MATLAB source code of the simulation software is available via the website http://micr.vub.ac.be.

  12. Ion current rectification, limiting and overlimiting conductances in nanopores.

    Science.gov (United States)

    van Oeffelen, Liesbeth; Van Roy, Willem; Idrissi, Hosni; Charlier, Daniel; Lagae, Liesbet; Borghs, Gustaaf

    2015-01-01

    Previous reports on Poisson-Nernst-Planck (PNP) simulations of solid-state nanopores have focused on steady state behaviour under simplified boundary conditions. These are Neumann boundary conditions for the voltage at the pore walls, and in some cases also Donnan equilibrium boundary conditions for concentrations and voltages at both entrances of the nanopore. In this paper, we report time-dependent and steady state PNP simulations under less restrictive boundary conditions, including Neumann boundary conditions applied throughout the membrane relatively far away from the nanopore. We simulated ion currents through cylindrical and conical nanopores with several surface charge configurations, studying the spatial and temporal dependence of the currents contributed by each ion species. This revealed that, due to slow co-diffusion of oppositely charged ions, steady state is generally not reached in simulations or in practice. Furthermore, it is shown that ion concentration polarization is responsible for the observed limiting conductances and ion current rectification in nanopores with asymmetric surface charges or shapes. Hence, after more than a decade of collective research attempting to understand the nature of ion current rectification in solid-state nanopores, a relatively intuitive model is retrieved. Moreover, we measured and simulated current-voltage characteristics of rectifying silicon nitride nanopores presenting overlimiting conductances. The similarity between measurement and simulation shows that overlimiting conductances can result from the increased conductance of the electric double-layer at the membrane surface at the depletion side due to voltage-induced polarization charges. The MATLAB source code of the simulation software is available via the website http://micr.vub.ac.be.

  13. Water Dissociation Phenomena on a Bipolar Membrane——Current-voltage Curve in Relation with Ionic Transport and Limiting Current Density

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The water dissociation mechanism on a bipolar membrane under the electrical field was investigated and characterized in terms of ionic transport and limiting current density. It is considered that the depletion layer exists at the junction of a bipolar membrane, which is coincided with the viewpoint of the most literatures, but we also consider that the thickness and conductivity of this layer is not only related with the increase of the applied voltage but also with the limiting current density. Below the limiting current density, the thickness of the depletion layer keeps a constant and the conductivity decreases with the increase of the applied voltage;while above the limiting current density, the depletion thickness will increase with the increase of the applied voltage and the conductivity keeps a very low constant. Based on the data reported in the literatures and independent determinations, the limiting current density was calculated and the experimental curves Ⅰ- Ⅴ in the two directions were compared with the theoretical calculations. It is demonstrated that above the limiting current density, the experimental results,either in the L-H direction or in the H-L direction, are consistent with the theoretical calculations; below the limiting current density, a slight deviation exists between the experimental and the theoretical results, and between the experimental results in the two directions. The change in Donnan potential due to the asymmetry of the mono-layers and the changes of ionic composition in the two directions is possibly responsible for this deviation.

  14. Experimental observation of direct current voltage-induced phase synchronization

    Indian Academy of Sciences (India)

    Haihong Li; Weiqing Liu; Qiongling Dai; Jinghua Xiao

    2006-09-01

    The dynamics of two uncoupled distinct Chua circuits driven by a common direct current voltage is explored experimentally. It was found that, with increasing current intensity, the dominant frequencies of these two Chua circuits will first vary at different speeds, approach an identical value for a certain current intensity and then separate. Techniques such as synchronization index and phase difference distribution were employed to analyze the phase coherence between these two Chua circuits.

  15. Noise limits of CMOS current interfaces for biosensors: a review.

    Science.gov (United States)

    Crescentini, Marco; Bennati, Marco; Carminati, Marco; Tartagni, Marco

    2014-04-01

    Current sensing readout is one of the most frequent techniques used in biosensing due to the charge-transfer phenomena occurring at solid-liquid interfaces. The development of novel nanodevices for biosensing determines new challenges for electronic interface design based on current sensing, especially when compact and efficient arrays need to be organized, such as in recent trends of rapid label-free electronic detection of DNA synthesis. This paper will review the basic noise limitations of current sensing interfaces with particular emphasis on integrated CMOS technology. Starting from the basic theory, the paper presents, investigates and compares charge-sensitive amplifier architectures used in both continuous-time and discrete-time approaches, along with their design trade-offs involving noise floor, sensitivity to stray capacitance and bandwidth. The ultimate goal of this review is providing analog designers with helpful design rules and analytical tools. Also, in order to present a comprehensive overview of the state-of-the-art, the most relevant papers recently appeared in the literature about this topic are discussed and compared.

  16. Simple voltage-controlled current source for wideband electrical bioimpedance spectroscopy: circuit dependences and limitations

    Science.gov (United States)

    Seoane, F.; Macías, R.; Bragós, R.; Lindecrantz, K.

    2011-11-01

    In this work, the single Op-Amp with load-in-the-loop topology as a current source is revisited. This circuit topology was already used as a voltage-controlled current source (VCCS) in the 1960s but was left unused when the requirements for higher frequency arose among the applications of electrical bioimpedance (EBI). The aim of the authors is not only limited to show that with the currently available electronic devices it is perfectly viable to use this simple VCCS topology as a working current source for wideband spectroscopy applications of EBI, but also to identify the limitations and the role of each of the circuit components in the most important parameter of a current for wideband applications: the output impedance. The study includes the eventual presence of a stray capacitance and also an original enhancement, driving with current the VCCS. Based on the theoretical analysis and experimental measurements, an accurate model of the output impedance is provided, explaining the role of the main constitutive elements of the circuit in the source's output impedance. Using the topologies presented in this work and the proposed model, any electronic designer can easily implement a simple and efficient current source for wideband EBI spectroscopy applications, e.g. in this study, values above 150 kΩ at 1 MHz have been obtained, which to the knowledge of the authors are the largest values experimentally measured and reported for a current source in EBI at this frequency.

  17. LIFELONG LEARNING THROUGH SECOND LIFE: CURRENT TRENDS, POTENTIALS AND LIMITATIONS

    Directory of Open Access Journals (Sweden)

    Nil GOKSEL-CANBEK

    2011-08-01

    Full Text Available Lifelong Learning (LLL has been a remarkable response to people-centered educational demand of 21st century. In order to provide effective formal, non-formal, and informal learning, immersive educational activities undertaken throughout life should be aimed to create a learning society in which people can experience individual and collective learning with no constrains of time or location. The concept of lifelong learning within the context of distance immersive education encompasses diverse 3D activities. The three dimensional, Web-based structured activities supported by distance learning technologies can be viewed as interactive tools which foster LLL. In this perspective, Second Life (SL can be regarded as one of the learning simulation milieus that allow learners to participate in various educational LLL activities in individual or group forms. The following paper examines how SL, taking advantage of its simulative nature and the possibility for creative interaction among participants, which are also common in games, allows the learners to participate in immersive constructivist learning activities. The article will also touch on the current uses of SL as a tool for LLL, as well as its potentials for further development according to the current trends in adult education. Further, the authors will discuss its limitations and will make suggestions towards a more complete pedagogical use.

  18. Evolution and current development of Transversal Themes: possibilities and limits

    Directory of Open Access Journals (Sweden)

    Carlos Rosales López

    2015-02-01

    Full Text Available The aim of this study was to determine the characteristics of the evolution and current development of transversal themes in education, considering them basically as important social cuestions with great influence in the overall education of the student. Specifically it seeks to clarify the level of preparation and dedication of teachers and schools to teach them. To do this, legislation used in our country (organics laws and decrees curriculum were analyzed and also the contribution of outstanding educators, institutions and researchers. We analyzed the characteristics of transversal themes in the educational project and the teaching program, its development in the clasroom and its projection out of it through the help of family and community. Conclusions about their current status (possibilities and limitations are derived and future proposals are made on the improvement of initial and ongoing training of teachers, to increase their collegiate or cooperative work of planning, intervention and evaluation, increased media and counseling in use, the need for increased communication and collaboration with families and other community institutions.How to reference this articleRosales López, C. (2015. Evolución y desarrollo actual de los Temas Transversales: posibilidades y límites. Foro de Educación, 13(18, pp. 143-160. doi: http://dx.doi.org/10.14516/fde.2015.013.018.008

  19. Superconducting matrix fault current limiter with current-driven trigger mechanism

    Science.gov (United States)

    Yuan, Xing

    2008-04-15

    A modular and scalable Matrix-type Fault Current Limiter (MFCL) that functions as a "variable impedance" device in an electric power network, using components made of superconducting and non-superconducting electrically conductive materials. An inductor is connected in series with the trigger superconductor in the trigger matrix and physically surrounds the superconductor. The current surge during a fault will generate a trigger magnetic field in the series inductor to cause fast and uniform quenching of the trigger superconductor to significantly reduce burnout risk due to superconductor material non-uniformity.

  20. Experimental Setup for the Investigation of Superconducting Persistent Current

    Science.gov (United States)

    2015-09-01

    NOTES 14. ABSTRACT We report on a recent experimental setup for the investigation of the relaxation rate of the persistent current in an assembly of...at cryo-temperatures in magnetic field at time scale of seconds to hours. 15. SUBJECT TERMS persistent current, 2G HTS, coated conductor, relaxation ... activation . One unknown aspect is the variation of the coils’ position with temperature from room to cryogenic. A better design of the coils assembly

  1. Circulating thyroid cancer biomarkers: Current limitations and future prospects.

    Science.gov (United States)

    Nixon, Alexander M; Provatopoulou, Xeni; Kalogera, Eleni; Zografos, George N; Gounaris, Antonia

    2017-08-01

    Differentiated thyroid cancer (DTC) is the most common malignancy of the endocrine system. There has been a significant increase in its incidence over the past two decades attributable mainly to the use of more sensitive diagnostic modalities. Ultrasound-guided fine needle aspiration cytology is the mainstay of diagnosis of benign disorders and malignancy. However, approximately 20% of lesions cannot be adequately categorized as benign or malignant. In the postoperative setting, monitoring of thyroglobulin (Tg) levels has been employed for the detection of disease recurrence. Unfortunately, Tg antibodies are common and interfere with Tg measurement in this subset of patients. Despite this limitation, Tg remains the sole widely used thyroid cancer biomarker in the clinical setting. In an attempt to bypass antibody interference, research has focused mainly on mRNA targets thought to be exclusively expressed in thyroid cells. Tg and thyroid stimulating hormone receptor (TSHR) mRNA have been extensively studied both for discerning between benign disease and malignancy and in postoperative disease surveillance. However, results among reports have been inconsistent probably reflecting considerable differences in methodology. Recently, microRNA (miRNA) targets are being investigated as potential biomarkers in DTC. MiRNAs are more stable molecules and theoretically are not as vulnerable as mRNA during manipulation. Initial results have been encouraging but large-scale studies are warranted to verify and elucidate their potential application in diagnosis and postoperative surveillance of thyroid cancer. Several other novel targets, primarily mutations and circulating cells, are currently emerging as promising thyroid cancer circulating biomarkers. Although interesting and intriguing, data are limited and derive from small-scale studies in specific patient cohorts. Further research findings demonstrating their value are awaited with anticipation. © 2017 John Wiley & Sons

  2. Current parallel I/O limitations to scalable data analysis.

    Energy Technology Data Exchange (ETDEWEB)

    Mascarenhas, Ajith Arthur; Pebay, Philippe Pierre

    2011-07-01

    This report describes the limitations to parallel scalability which we have encountered when applying our otherwise optimally scalable parallel statistical analysis tool kit to large data sets distributed across the parallel file system of the current premier DOE computational facility. This report describes our study to evaluate the effect of parallel I/O on the overall scalability of a parallel data analysis pipeline using our scalable parallel statistics tool kit [PTBM11]. In this goal, we tested it using the Jaguar-pf DOE/ORNL peta-scale platform on a large combustion simulation data under a variety of process counts and domain decompositions scenarios. In this report we have recalled the foundations of the parallel statistical analysis tool kit which we have designed and implemented, with the specific double intent of reproducing typical data analysis workflows, and achieving optimal design for scalable parallel implementations. We have briefly reviewed those earlier results and publications which allow us to conclude that we have achieved both goals. However, in this report we have further established that, when used in conjuction with a state-of-the-art parallel I/O system, as can be found on the premier DOE peta-scale platform, the scaling properties of the overall analysis pipeline comprising parallel data access routines degrade rapidly. This finding is problematic and must be addressed if peta-scale data analysis is to be made scalable, or even possible. In order to attempt to address these parallel I/O limitations, we will investigate the use the Adaptable IO System (ADIOS) [LZL+10] to improve I/O performance, while maintaining flexibility for a variety of IO options, such MPI IO, POSIX IO. This system is developed at ORNL and other collaborating institutions, and is being tested extensively on Jaguar-pf. Simulation code being developed on these systems will also use ADIOS to output the data thereby making it easier for other systems, such as ours, to

  3. Experimental typography : reviewing the modernist and the current approaches

    OpenAIRE

    Makal, Eray

    1993-01-01

    Ankara : The Department of Graphic Design and Institute of Fine Arts, Bilkent Univ., 1993. Thesis (Master's) -- Bilkent University, 1993. Includes bibliographical references leaves 65-66. The intention of this study is to evaluate the experimental typography within the history of graphic design by taking in consideration of two epochs. The Modernist and The Current. Makal, Eray M.S.

  4. Halo current diagnostic system of experimental advanced superconducting tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Chen, D. L.; Shen, B.; Sun, Y.; Qian, J. P., E-mail: jpqian@ipp.ac.cn; Wang, Y.; Xiao, B. J. [Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei 230031 (China); Granetz, R. S. [MIT Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States)

    2015-10-15

    The design, calibration, and installation of disruption halo current sensors for the Experimental Advanced Superconducting Tokamak are described in this article. All the sensors are Rogowski coils that surround conducting structures, and all the signals are analog integrated. Coils with two different cross-section sizes have been fabricated, and their mutual inductances are calibrated. Sensors have been installed to measure halo currents in several different parts of both the upper divertor (tungsten) and lower divertor (graphite) at several toroidal locations. Initial measurements from disruptions show that the halo current diagnostics are working well.

  5. Halo current diagnostic system of experimental advanced superconducting tokamak

    Science.gov (United States)

    Chen, D. L.; Shen, B.; Granetz, R. S.; Sun, Y.; Qian, J. P.; Wang, Y.; Xiao, B. J.

    2015-10-01

    The design, calibration, and installation of disruption halo current sensors for the Experimental Advanced Superconducting Tokamak are described in this article. All the sensors are Rogowski coils that surround conducting structures, and all the signals are analog integrated. Coils with two different cross-section sizes have been fabricated, and their mutual inductances are calibrated. Sensors have been installed to measure halo currents in several different parts of both the upper divertor (tungsten) and lower divertor (graphite) at several toroidal locations. Initial measurements from disruptions show that the halo current diagnostics are working well.

  6. Predicting size effect on diffusion-limited current density of oxygen reduction by copper wire

    Institute of Scientific and Technical Information of China (English)

    LU Yonghong; XU Haibo; WANG Jia; ZHONG Lian

    2011-01-01

    The size effect of copper wire radius (0.04鈥?.82 mm) on the diffusion-limited current density of an oxygen reduction reaction in stagnant simulated seawater (naturally aerated 0.5 mol/L NaCl) is investigated by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) and compared with the results obtained in 0.5 mol/L H2SO4. In the oxygen diffusion-limited range, size effect is found to occur independent of electrolytes, which is attributed to non-linear diffusion. Additionally, to satisfy application in a marine setting, an empirical equation correlating oxygen diffusion-limited current density to copper wire radius is proposed by fitting experimental data.

  7. Limit currents and value distribution of holomorphic maps

    CERN Document Server

    Buurns, Daniel

    2010-01-01

    We construct $d$-closed and $dd^c$-closed positive currents associated to a holomorphic map $\\phi$ via cluster points of normalized weighted truncated image currents. They are constructed using analogues of the Ahlfors length-area inequality in higher dimensions. Such classes of currents are loosely referred to as Ahlfors currents. We give some applications to equidistribution problems in value distribution theory.

  8. A direct experimental limit on neutron -- mirror neutron oscillations

    CERN Document Server

    Ban, G; Naviliat-Cuncic, O; Bodek, K; Kistryn, S; Kuzniak, M; Zejma, J; Khomutov, N; Knowles, P; Rebetez, M; Weis, A; Plonka, C; Rogel, G; Quéméner, G; Rebreyend, D; Roccia, S; Tur, M; Daum, M; Henneck, R; Heule, S; Kasprzak, M; Kirch, K; Knecht, A; Mtchedlishvili, A; Zsigmond, G

    2007-01-01

    In case a mirror world with a copy of our ordinary particle spectrum would exist, the neutron n and its degenerate partner, the mirror neutron ${\\rm n'}$, could potentially mix and undergo ${\\rm nn'}$ oscillations. The interaction of an ordinary magnetic field with the ordinary neutron would lift the degeneracy between the mirror partners, diminish the ${\\rm n'}$-amplitude in the n-wavefunction and, thus, suppress its observability. We report an experimental comparison of ultracold neutron storage in a trap with and without superimposed magnetic field. No influence of the magnetic field is found and a limit on the oscillation time $\\tau_{\\rm nn'} > 103$ s (95% C.L.) is derived.

  9. On-chip temperature monitoring of a SiC current limiter

    Energy Technology Data Exchange (ETDEWEB)

    Tournier, D.; Godignon, P.; Millan, J. [Centro Nacional de Microelectronica (CNM), Univ. Autonoma de Barcelona, Bellaterra (Spain); Planson, D.; Chante, J.P. [Centre de Genie Electrique de Lyon (CEGELY) INSA-LYON, UMR 5005 CNRS, Villeurbanne (France); Sarrus, F.; Palma, J.F. de [Ferraz Shawmut, Bonnet de Mure (France)

    2004-07-01

    High voltage and high current potentiality of SiC based devices has been proved, and various devices able to work at high temperature have been reported as well. Nevertheless, packaging is one of the main constrains for high temperature operation of these devices. Up to date, no specific power package has been reported for high temperature operation. Moreover, it is desirable to predict the SiC die temperature to avoid any related failure in order to improve the efficiency of the packaged SiC device. This paper deals with an integrated temperature sensor for SiC current limiting devices. The current limiter is based on a VJFET structure, which capability for dissipating high power density (140 kW/cm{sup 2}), in the limiting state, has been previously demonstrated. Carrier mobility dependence with temperature was extracted from cryogenic measurements. The temperature estimation is based on the measurement of the variation of the electrical resistance (caused by mobility variation) of the sensing device integrated with the current limiter. In this paper we first describe the temperature estimation methodology using various technological solution (from metallic resistor solution to the SiC integrated sensor). Then experimental temperature measurements using an integrated SiC sensor within a packaged current limiting devices will be presented. Electro-thermal measurements on the fabricated devices show that the current limiter is able to work at 205 C under steady state conditions (320 V), without degrading their electrical performances. Finally, perspectives in terms of integration and reliability will be proposed. (orig.)

  10. Path-constrained robot control with limited torques -- Experimental evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Dahl, O. (Lund Univ., Malmoe (Sweden))

    1994-10-01

    Fast motion along a predefined path is important in many robot applications, and requires utilization of the maximum allowable torque range. If the torque is at the limit, there is no margin to cope with disturbances or modeling errors, which may result in deviation from the path. A path velocity controller for modification of the velocity along the path when the torques saturate can improve path tracking. The path velocity controller acts as an outer feedback loop outside the ordinary robot controller, and modifies a nominal velocity profile, computed by minimum time optimization using available methods. An experimental evaluation of such a controller is presented. The experiments are done on an industrial robot, where the original robot control system has been replaced by a VME-based computer system. The experimental results demonstrate that the path velocity controller can adjust a nominal minimum time velocity profile, such that the result is good path following and good utilization of the available torque range. It is also demonstrated how the path velocity controller is able to compensate for time variations in the robot dynamics.

  11. Improved experimental limit on the EDM of 225Ra

    Science.gov (United States)

    Bishof, Michael; Bailey, Kevin; Dietrich, Matthew R.; Greene, John P.; Holt, Roy J.; Kalita, Mukut R.; Korsch, Wolfgang; Lemke, Nathan D.; Lu, Zheng-Tian; Mueller, Peter; O'Connor, Tom P.; Parker, Richard H.; Rabga, Tenzin; Singh, Jaideep T.

    2015-10-01

    Searches for permanent electric dipole moments (EDMs) in fundamental and composite particles are sensitive probes of beyond-standard-model symmetry violation that could explain the dominance of matter over anti-matter. The 225Ra (t1/2 = 15d, I = 1/2) atom is a particularly attractive system to use for an EDM measurement because its large nuclear octupole deformation, closely spaced ground-state parity doublet, and large atomic mass make 225Ra uniquely sensitive to symmetry-violating interactions in the nuclear medium. We have developed an experiment to measure the EDM of 225Ra and demonstrated the first ``proof-of-principle'' measurement, giving a 95% confidence upper limit of 5E-22 e-cm. After implementing a vacuum upgrade, we have observed nuclear spin coherence after 20 s of free evolution - a factor of ten improvement over our earlier results - and have lowered the 225Ra EDM limit by over an order of magnitude. Upcoming experimental upgrades have the potential to further improve our EDM sensitivity by many orders of magnitude, allowing us to test symmetry violation at an unprecedented level. This work is supported by U.S. DOE, Office of Science, Office of Nuclear Physics, under Contract DE-AC02-06CH11357.

  12. Current experimental situation in heavy-ion reactions

    Energy Technology Data Exchange (ETDEWEB)

    Scott, D.K.

    1978-06-01

    A detailed survey of the present experimental situation in heavy-ion physics is presented. The discussion begins by considering the simple excitation of discrete states in elastic scattering, transfer, and compound-nucleus reactions; it then turns to more drastic perturbations of the nucleus high in the continuum through fusion, fission, and deeply inelastic scattering, and concludes with the (possibly) limiting asymptotic phenomena of relativistic heavy-ion collisions. 138 figures, 5 tables, 451 references. (RWR)

  13. Experimental Gravity Currents Propagating Downslope Over A Synthetic Topography

    Science.gov (United States)

    Burgos Cuevas, Andrea; Ruiz-Angulo, Angel; Palacios-Morales, Carlos

    2016-11-01

    Lock-release gravity currents are studied experimentally in order to investigate their dynamics and the mixing process between them and the ambient fluid. We produced these currents in a laboratory tank and allow them to propagate downslope first in a flat slope and then in a rough one with a synthetic topography. This topography is similar to the one of a side of a mountain near mexico's valley. Our aim is to investigate the dynamics of gravity currents as similar as possible to the mountain breezes that can develop around this valley. To the best of our knowledge, there are few experimental investigations that take into account the roughness of the slope. For each experiment, we obtain the instantaneous velocity fields using the standard piv technique. From the velocity fields, we estimate the entrainment coefficient time series. We found that this coefficient depends on the roughness of the surface where the current propagates. Besides, pressure time series were obtained in synthetic stations along the rough profile. These series showed a very clear signal of the gravity current propagating along the slope.

  14. Experimental observations of stray current effects on steel fibres embedded in mortar

    DEFF Research Database (Denmark)

    Solgaard, A.O.S.; Carsana, M.; Geiker, M.R.;

    2013-01-01

    It is known that stray direct current can cause corrosive damage over time to bar reinforced concrete, but knowledge on the consequences to steel fibre reinforced concrete is limited. This paper presents analyses and corresponding results from an experimental program (parametric study) investigat...

  15. On Dynamic Range Limitations of CMOS Current Conveyors

    DEFF Research Database (Denmark)

    Bruun, Erik

    1999-01-01

    This paper is concerned with the dynamic range of continuous time CMOS current mode circuits. As a representative current mode device a class AB current conveyor is examined. First, the voltage input range of the high impedance Y input is investigated. Next, the current input range of the low...... frequency band and for the situation where the conveyor is used over the full bandwidth achievable. Finally, the optimisation of the current input range is related to the distortion characteristics and it is pointed out that to a first order approximation the distortion is independent of the current range....... impedance X input is investigated. It is compared to the thermal noise in the X to Z signal path in order to evaluate the dynamic range, and the dependencies of the dynamic range on the supply voltage and the transistor lay-out is derived, both for the situation where the conveyor is used over a narrow...

  16. Novel Topology of Saturated-core Fault Current Limiter

    NARCIS (Netherlands)

    Cvoric, D.

    2010-01-01

    Increasing levels of fault currents in utility grids are expected to result in mechanical and thermal overstresses of different power system components. To cope with these increased levels, expensive upgrades and replacements of currently employed Circuit Breakers might be required in the near futur

  17. Experimental simulation of gravity currents in erodible bed

    Science.gov (United States)

    Bateman, A.; La Roca, M.; Medina, V.

    2009-04-01

    Gravity currents are commonly met in nature, when a flow of denser fluid moves into a less dense one. A typical example of a gravity current is given by the sea water which flows into the bottom of a river during the summer, in correspondence of the estuary, when the river's discharge attains low values. In this case, dangerous consequences can occur, because of the polluting of the aquifer caused by the salty water. Density currents also occurs in lakes and reservoirs, because of a change in temperature or because a flood, both can produce some environmental impacts that are of interest to the local water Agency of the different countries. Of particular relevance is also the interaction of the gravity current with the movement of the sediments from the bottom of the bed. The international state of the art is particularly concerned with experimental and numerical investigation on gravity currents on fixed and porous bed [1-2-3], while, to the authors' knowledge, the interaction of a gravity current with an erodible bed is still an open field of investigation. In this paper experiments concerning with the propagation of a gravity current over fixed and erodible bed are presented. The experiments, conducted at the laboratory of Hydraulics of the Universitat Politecnica de Catalunya (actually in the Prof. Bateman's blue room), were concerned with a transparent tank 2 m long, 0.2 m wide and 0.3 m deep, partly filled with salty water and partly with fresh water, up to a depth of 0.28 m. The salty water, whose density was in the range 1050John E. Simpson. Gravity Currents [3] J.J. Monaghan, R.A.F. Cas, A.M. Kos, M. Hallworth, Gravity currents descending a ramp in a stratified tank, The Journal of Fluid Mechanics, Vol. 379, 1999

  18. Space-charge-limited leakage current in high dielectric constant and ferroelectric thin films considering the field-dependent permittivity

    Science.gov (United States)

    Sun, J.; Zheng, X. J.; Yin, W.; Tang, M. H.; Li, W.

    2010-12-01

    Distinguishing from the traditional characterization on high-field leakage current density-voltage relationship, the field-dependent permittivity from the polarization derivative is used to solve the space-charge-limited conduction, and the simulated leakage current densities are compared with the previous experimental observations. The influences of the mobility, ferroelectric parameters, and film thickness on the leakage current densities are discussed. The results verify that the high-field quasi-Ohmic region observed experimentally may result from the field-dependent permittivity, and that the leakage current can be influenced by the ferroelectric polarization.

  19. Limitations Of The Current State Space Modelling Approach In Multistage Machining Processes Due To Operation Variations

    Science.gov (United States)

    Abellán-Nebot, J. V.; Liu, J.; Romero, F.

    2009-11-01

    The State Space modelling approach has been recently proposed as an engineering-driven technique for part quality prediction in Multistage Machining Processes (MMP). Current State Space models incorporate fixture and datum variations in the multi-stage variation propagation, without explicitly considering common operation variations such as machine-tool thermal distortions, cutting-tool wear, cutting-tool deflections, etc. This paper shows the limitations of the current State Space model through an experimental case study where the effect of the spindle thermal expansion, cutting-tool flank wear and locator errors are introduced. The paper also discusses the extension of the current State Space model to include operation variations and its potential benefits.

  20. Predicting the behavioural impact of transcranial direct current stimulation: issues and limitations

    Directory of Open Access Journals (Sweden)

    Archy Otto De Berker

    2013-10-01

    Full Text Available The transcranial application of weak currents to the human brain has enjoyed a decade of success, providing a simple and powerful tool for non-invasively altering human brain function. However, our understanding of current delivery and its impact upon neural circuitry leaves much to be desired. We argue that the credibility of conclusions drawn with tDCS is contingent upon realistic explanations of how tDCS works, and that our present understanding of tDCS limits the technique’s use to localize function in the human brain. We outline two central issues where progress is required: the localization of currents, and predicting their functional consequence. We encourage experimenters to eschew simplistic explanations of mechanisms of transcranial current stimulation. We suggest the use of individualized current modelling, together with computational neurostimulation to inform mechanistic frameworks in which to interpret the physiological impact of tDCS. We hope that through mechanistically richer descriptions of current flow and action, insight into the biological processes by which transcranial currents influence behaviour can be gained, leading to more effective stimulation protocols and empowering conclusions drawn with tDCS.

  1. Experimental flammability limits and associated theoretical flame temperatures as a tool for predicting the temperature dependence of these limits

    OpenAIRE

    Zlochower, Isaac A.

    2012-01-01

    The utility and limitations of adiabatic flame temperature calculations and minimum mixture energies in predicting the temperature dependence of flammability limits are explored. The limiting flame temperatures at constant pressure (1 bar) are calculated using a standard widely-used thermodynamic computer program. The computation is based on the calculated limiting flame temperature value at the reference initial temperature and the experimental limit concentration. The values recently determ...

  2. Limitations of eddy current testing in a fast reactor environment

    Science.gov (United States)

    Wu, Tao; Bowler, John R.

    2016-02-01

    The feasibility of using eddy current probes for detecting flaws in fast nuclear reactor structures has been investigated with the aim of detecting defects immersed in electrically conductive coolant including under liquid sodium during standby. For the inspections to be viable, there is a need to use an encapsulated sensor system that can be move into position with the aid of visualization tools. The initial objective being to locate the surface to be investigated using, for example, a combination of electromagnetic sensors and sonar. Here we focus on one feature of the task in which eddy current probe impedance variations due to interaction with the external surface of a tube are evaluated in order to monitor the probe location and orientation during inspection.

  3. Current status of nuclear medicine in chronic airflow limitation

    Energy Technology Data Exchange (ETDEWEB)

    Clarke, S.W.; Agnew, J.E.

    1987-06-01

    Radionuclide imaging, quite apart from its role in the diagnosis of pulmonary embolism, offers information about the distribution of ventilatory and perfusion abnormalities within the lung. The extent of ventilatory abnormality seen can be related to the severity of airways obstruction as assessed spirometrically, whilst abnormalities in the matching of perfusion to ventilation can be related to the severity of hypoxaemia in patients with chronic airflow limitation. Clearance of mucus from the lungs of patients with chronic mucus hypersection may be assessed by following the clearance rate of insoluble radioaerosol particles; by such means the relative contributions of mucociliary transport and of cough to the overall clearance can be observed. Clearance is often severely impaired in patients with airways obstruction; the radioaerosol technique can be used to determine the effects of drug or physiotherapy treatment. Chronic airflow limitation leading to hypoxaemia can be associated with pulmonary artery hypertension and right ventricular hypertrophy - this may be investigated noninvasively by a radionuclide test of right ventricular ejection fraction.

  4. 基于自收缩效应液态金属限流器中电弧行为特性的实验研究%Experimental Research of Arc Behaviour Characteristics in Liquid Metal Current Limiter Based on Self Pinch Effect

    Institute of Scientific and Technical Information of China (English)

    刘懿莹; 吴翊; 荣命哲; 何海龙; 李阳; 刘宏

    2012-01-01

    研究基于自收缩效应液态金属限流器(LMCL)中的电弧行为特性。设计了具有LMCL基本结构特征的实验模型。利用高速摄影技术获得的起弧和燃弧过程的影像以及通过数字示波器记录的电弧电压和电流波形,揭示了液态金属中电弧起弧机理,分析了电流对弧前自收缩过程的影响,研究了在单孔条件下电弧形态随电弧电压的演变规律。同时在实验过程中发现了电弧对电极的侵蚀现象,并通过分析其成因提出一种能够有效避免侵蚀的电极结构改进方法。该研究对进一步提高LMCL限流性能具指导意义。%The arc behavior characteristics in the liquid metal current limiter(LMCL) based on self pinch effect was investigated. An experimental setup which had basic structural characteristic of LMCL was designed. According to the images obtained the high speed photography and the waveform of arc voltage and current recorded by the oscilloscope, the nature of arc initiation in liquid metal is revealed, and the influence of current on the self pinch process of pre arcing is analyzed. The morphological changes of arc with the variation of arc voltage in one channel are studied. The phenomenon of arc erosion on the electrodes is observed during the experiment. An improved method of electrode structure, which can avoid the erosion effectively, is proposed.The research work is a significant guide to the improvement of LMCL current limiting charateristics.

  5. PRA: A PERSPECTIVE ON STRENGTHS, CURRENT LIMITATIONS, AND POSSIBLE IMPROVEMENTS

    Directory of Open Access Journals (Sweden)

    ALI MOSLEH

    2014-02-01

    Full Text Available Probabilistic risk assessment (PRA has been used in various technological fields to assist regulatory agencies, managerial decision makers, and systems designers in assessing and mitigating the risks inherent in these complex arrangements. Has PRA delivered on its promise? How do we gage PRA performance? Are our expectations about value of PRA realistic? Are there disparities between what we get and what we think we are getting form PRA and its various derivatives? Do current PRAs reflect the knowledge gained from actual events? How do we address potential gaps? These are some of the questions that have been raised over the years since the inception of the field more than forty years ago. This paper offers a brief assessment of PRA as a technical discipline in theory and practice, its key strengths and weaknesses, and suggestions on ways to address real and perceived shortcomings.

  6. Formation of a spark discharge in an inhomogeneous electric field with current limitation by a large ballast Resistance

    Energy Technology Data Exchange (ETDEWEB)

    Baldanov, B. B., E-mail: baibat@mail.ru [Russian Academy of Sciences, Institute of Physical Material Science, Siberian Branch (Russian Federation)

    2016-01-15

    Results of studies of a spark discharge initiated in argon in a point–plane electrode gap with limitation of the discharge current by a large ballast resistance are presented. It is shown that the current flowing through the plasma channel of such a low-current spark has the form of periodic pulses. It is experimentally demonstrated that, when a low-current spark transforms into a constricted glow discharge, current pulses disappear, the spatial structure of the cathode glow changes abruptly, and a brightly glowing positive plasma column forms in the gap.

  7. Fighting Sharka in Peach: Current Limitations and Future Perspectives

    Science.gov (United States)

    Cirilli, Marco; Geuna, Filippo; Babini, Anna R.; Bozhkova, Valentina; Catalano, Luigi; Cavagna, Beniamino; Dallot, Sylvie; Decroocq, Véronique; Dondini, Luca; Foschi, Stefano; Ilardi, Vincenza; Liverani, Alessandro; Mezzetti, Bruno; Minafra, Angelantonio; Pancaldi, Marco; Pandolfini, Tiziana; Pascal, Thierry; Savino, Vito N.; Scorza, Ralph; Verde, Ignazio; Bassi, Daniele

    2016-01-01

    Sharka, caused by Plum Pox Virus (PPV), is by far the most important infectious disease of peach [P. persica (L.) Batsch] and other Prunus species. The progressive spread of the virus in many important growing areas throughout Europe poses serious issues to the economic sustainability of stone fruit crops, peach in particular. The adoption of internationally agreed-upon rules for diagnostic tests, strain-specific monitoring schemes and spatial–temporal modeling of virus spread, are all essential for a more effective sharka containment. The EU regulations on nursery activity should be modified based on the zone delimitation of PPV presence, limiting open-field production of propagation materials only to virus-free areas. Increasing the efficiency of preventive measures should be augmented by the short-term development of resistant cultivars. Putative sources of resistance/tolerance have been recently identified in peach germplasm, although the majority of novel resistant sources to PPV-M have been found in almond. However, the complexity of introgression from related-species imposes the search for alternative strategies. The use of genetic engineering, particularly RNA interference (RNAi)-based approaches, appears as one of the most promising perspectives to introduce a durable resistance to PPV in peach germplasm, notwithstanding the well-known difficulties of in vitro plant regeneration in this species. In this regard, rootstock transformation to induce RNAi-mediated systemic resistance would avoid the transformation of numerous commercial cultivars, and may alleviate consumer resistance to the use of GM plants. PMID:27625664

  8. Fighting Sharka in Peach: Current Limitations and Future Perspectives

    Directory of Open Access Journals (Sweden)

    Marco Cirilli

    2016-08-01

    Full Text Available Sharka, caused by Plum Pox Virus (PPV, is by far the most important infectious disease of peach [P. persica (L. Batsch] and other Prunus species. The progressive spread of the virus in many important growing areas throughout Europe poses serious issues to the economic sustainability of stone fruit crops, peach in particular. The adoption of internationally agreed-upon rules for diagnostic tests, strain-specific monitoring schemes and spatial-temporal modeling of virus spread, are all essential for a more effective sharka containment. The EU regulations on nursery activity should be modified based on the zone delimitation of PPV presence, limiting open-field production of propagation materials only to virus-free areas. Increasing the efficiency of preventive measures should be augmented by the short-term development of resistant cultivars. Putative sources of resistance/tolerance have been recently identified in peach germplasm, although the majority of novel resistant sources to PPV-M have been found in almond. However, the complexity of introgression from related-species imposes the search for alternative strategies. The use of genetic engineering, particularly RNAi-based approaches, appears as one of the most promising perspectives to introduce a durable resistance to PPV in peach germplasm, notwithstanding the well-known difficulties of in vitro plant regeneration in this species. In this regard, rootstock transformation to induce RNAi-mediated systemic resistance to PPV would avoid the transformation of numerous commercial cultivars, and may alleviate consumer resistance to the use of GM plants.

  9. Experimental Verification of Current Shear Design Equations for HSRC Beams

    Directory of Open Access Journals (Sweden)

    Attaullah Shah

    2012-07-01

    Full Text Available Experimental research on the shear capacity of HSRC (High Strength Reinforced Concrete beams is relatively very limited as compared to the NSRC (Normal Strength Reinforced Concrete beams. Most of the Building Codes determine the shear strength of HSRC with the help of empirical equations based on experimental work of NSRC beams and hence these equations are generally regarded as un-conservative for HSRC beams particularly at low level of longitudinal reinforcement. In this paper, 42 beams have been tested in two sets, such that in 21 beams no transverse reinforcement has been used, whereas in the remaining 21 beams, minimum transverse reinforcement has been used as per ACI-318 (American Concrete Institute provisions. Two values of compressive strength 52 and 61 MPa, three values of longitudinal steel ratio and seven values of shear span to depth ratio have been have been used. The beams were tested under concentrated load at the mid span. The results are compared with the equations proposed by different international building codes like ACI, AASHTO LRFD, EC (Euro Code, Canadian Code and Japanese Code for shear strength of HSRC beams.From comparison, it has been observed that some codes are less conservative for shear design of HSRC beams and further research is required to rationalize these equations.

  10. Experimental Investigation of Turbulence Specifications of Turbidity Currents

    Directory of Open Access Journals (Sweden)

    B Firoozabadi

    2010-01-01

    Full Text Available The present study investigates the turbulence characteristic of turbidity current experimentally. The three-dimensional Acoustic-Doppler Velocimeter (ADV was used to measure the instantaneous velocity and characteristics of the turbulent flow. The experiments were conducted in a three-dimensional channel for different discharge flows, concentrations, and bed slopes. Results are expressed at various distances from the inlet, for all flow rates, slopes and concentrations as the distribution of turbulence energy, Reynolds stress and the turbulent intensity. It was concluded that the maximum turbulence intensity happens in both the interface and near the wall. Also, it was observed that the turbulence intensity reaches its minimum where maximum velocity occurs.

  11. Recent experimental results of KSTAR RF heating and current drive

    Energy Technology Data Exchange (ETDEWEB)

    Wang, S. J., E-mail: sjwang@nfri.re.kr; Kim, J.; Jeong, J. H.; Kim, H. J.; Joung, M.; Bae, Y. S.; Kwak, J. G. [National Fusion Research Institute, Daejoen, 305-806 (Korea, Republic of)

    2015-12-10

    The overview of KSTAR activities on ICRH, LHCD and ECH/CD including the last experimental results and future plan aiming for long-pulse high-beta plasma will be presented. Recently we achieved reasonable coupling of ICRF power to H-mode plasma through several efforts to increase system reliability. Power balance will be discussed on this experiment. LHCD is still struggling in the low power regime. Review of antenna spectrum for the higher coupling in H-mode plasma will be tried. ECH/CD provides 41 sec, 0.8 MW of heating power to support high-performance long-pulse discharge. Also, 170 GHz ECH system is integrated with the Plasma Control System (PCS) for the feedback controlling of NTM. Status and plan of ECH/CD will be discussed. Finally, helicon current drive is being prepared for the next stage of KSTAR operation. The hardware preparation and the calculation results of helicon current drive in KSTAR plasma will be discussed.

  12. Experimental optical phase measurement at the exact Heisenberg limit (Conference Presentation)

    Science.gov (United States)

    Daryanoosh, Shakib; Slussarenko, Sergei; Wiseman, Howard M.; Pryde, Geoff J.

    2016-10-01

    Optical phase measurement through its application in quantum metrology has pushed the precision limit with which some physical quantities can be measured accurately. At the very fundamental level, the laws of quantum mechanics dictate that the uncertainty in phase estimations scales as 1/N, where N is the number of quantum resources employed in the protocol [1]. This is the well known Heisenberg limit (HL) which is quadratically better than the traditional precision limit known as the standard quantum limit (SQL) with uncertainty asymptotically scaling as 1/&sqrt{N} [1]. Several experiments have demonstrated that the SQL can be beaten by using an entangled state as the probe and a specific measurement scheme for ab initio estimation of unknown phases [2,3]. It has also been shown experimentally that even in the absence of the entanglement one can measure an unknown phase with imprecision scaling at the HL [4]. In this work we first present a new protocol able to estimate an optical phase at the Heisenberg limit, and then experimentally explore fundamental and practical issues in generating high-quality novel entangled states, for use in this protocol and beyond. Our aim in this study is to measure an unknown phase in the interval [0,2π) with uncertainty attaining the exact HL. There is a condition that should be met to address this objective: preparation of an optimal state [5]. This would cover part of the presentation through which we explain how to experimentally realise such an optimal state with the current technological limitations and the feasibility of the scheme. In particular, we generate an entangled 3-photon (2-photon) state of specific superposition of GHZ (Bell) states. Our numerical simulation of the phase measurement gate together with the experimental outcomes show that the created state should have a high fidelity and purity to be able to have the phase uncertainty achieving the exact HL. Therefore, we briefly explain the modelling for

  13. SUSY effects in $R_b$: revisited under current experimental constraints

    CERN Document Server

    Su, Wei

    2016-01-01

    In this note we revisit the effects of natural SUSY in $R_b$ under current experimental constraints including the LHC Higgs data, the $B$-physics measurements, the dark matter relic density and direct detection limits, as well as the precision electroweak data. We first perform a scan to figure out the currently allowed parameter space of natural SUSY and then display the SUSY effects in $R_b$. We find that although the SUSY parameter space has been severely restrained by current experimental data, natural SUSY can still alter $R_b$ with a magnitude sizable enough to be observed at future $Z$-factories (ILC, CEPC, FCC-ee, Super $Z$-factory) which produce $10^9-10^{12}$ $Z$-bosons.

  14. Experimental Limits on Gravitational Waves in the MHz frequency Range

    Energy Technology Data Exchange (ETDEWEB)

    Lanza, Robert Jr. [Univ. of Chicago, IL (United States)

    2015-03-01

    This thesis presents the results of a search for gravitational waves in the 1-11MHz frequency range using dual power-recycled Michelson laser interferometers at Fermi National Accelerator Laboratory. An unprecedented level of sensitivity to gravitational waves in this frequency range has been achieved by cross-correlating the output fluctuations of two identical and colocated 40m long interferometers. This technique produces sensitivities better than two orders of magnitude below the quantum shot-noise limit, within integration times of less than 1 hour. 95% confidence level upper limits are placed on the strain amplitude of MHz frequency gravitational waves at the 10-21 Hz-1/2 level, constituting the best direct limits to date at these frequencies. For gravitational wave power distributed over this frequency range, a broadband upper limit of 2.4 x 10-21Hz-1/2 at 95% confidence level is also obtained. This thesis covers the detector technology, the commissioning and calibration of the instrument, the statistical data analysis, and the gravitational wave limit results. Particular attention is paid to the end-to-end calibration of the instrument’s sensitivity to differential arm length motion, and so to gravitational wave strain. A detailed statistical analysis of the data is presented as well.

  15. Experimental research of limits for thermal modulation transfer function

    Directory of Open Access Journals (Sweden)

    Tomić Ljubiša D.

    2009-01-01

    Full Text Available The paper presented testing of surface defects by pulse video thermography techniques. Such techniques rely on transient infrared radiation from the sample heated by the short duration flux initiated by flesh. Experimental measurements are realized by infrared sensor (FLIR camera. Testing results are considered for the samples with controlled designed defects beyond observed surfaces. The effects of response through the transparent wall are measured as infrared visible radiance. Researches with controlled samples are performed to verify visibility threshold of defect dimensions and forms, for possible use as modulation transfer function of defects hidden beyond the surfaces of thin metal walls. Dimensionless coefficients are derived for method estimations as the results from experimental research.

  16. Melt textured YBaCuO transport current capability. Application to current limitation; Capacite de transport et de limitation du courant des materiaux YBaCuO textures

    Energy Technology Data Exchange (ETDEWEB)

    Porcar, L.; Belmont, O.; Noudem, J.G.; Barbut, J.M.; Barrault, M. [Schneider Electric S.A., Grenoble (France); Bourgault, D.; Chaud, X.; Tournier, R. [CNRS-EPM/Matformag, Grenoble (France); Tixador, P. [CNRS-CRTBT/LEG, Grenoble (France)

    1998-01-01

    Pulsed and permanent sinusoidal transport current have been applied to melt textured Y{sub 1}Ba{sub 2}Cu{sub 3}O{sub 7-{delta}} in order to estimate its current limitation capability. High pulsed transport currents reaching 9000A (23000 A/cm{sup 2}) crossed a 4 cm long sample. In permanent sinusoidal current, 3000 A (7800 A/cm{sup 2}) crossed the sample without showing any resistive losses. Above the critical current, the transition from the superconducting to the normal state is strongly abrupt. (orig.). 8 refs.

  17. Evaluation of Ferrite Chip Beads as Surge Current Limiters in Circuits with Tantalum Capacitors

    Science.gov (United States)

    Teverovsky, Alexander

    2014-01-01

    Limiting resistors are currently required to be connected in series with tantalum capacitors to reduce the risk of surge current failures. However, application of limiting resistors decreases substantially the efficiency of the power supply systems. An ideal surge current limiting device should have a negligible resistance for DC currents and high resistance at frequencies corresponding to transients in tantalum capacitors. This work evaluates the possibility of using chip ferrite beads (FB) as such devices. Twelve types of small size FBs from three manufacturers were used to evaluate their robustness under soldering stresses and at high surge current spikes associated with transients in tantalum capacitors. Results show that FBs are capable to withstand current pulses that are substantially greater than the specified current limits. However, due to a sharp decrease of impedance with current, FBs do not reduce surge currents to the required level that can be achieved with regular resistors.

  18. ITER (International Thermonuclear Experimental Reactor) current drive and heating physics

    Energy Technology Data Exchange (ETDEWEB)

    Nevins, W.M.; Lindquist, W. (Lawrence Livermore National Lab., CA (USA)); Fujisawa, N.; Kimura, H. (Japan Atomic Energy Research Inst., Naka, Ibaraki (Japan)); Hopman, H.; Rebuffi, L.; Wegrowe, J.G. (Max-Planck-Institut fuer Plasmaphysik, Garching (Germany, F.R.). NET Design Team); Parail, V.; Vdovin, V. (Gosudarstvennyj Komitet po Ispol' zovaniyu Atomnoj Ehnergii SSSR, Moscow (USSR). Inst. Atomnoj Ehn

    1990-01-01

    The ITER Current Drive and Heating (CD H) systems are required for: Ionization and current initiation; Non-inductive current ramp-up assist; Heating of the plasma; Steady-state operation with full non-inductive current drive; Current profile control; and Burn control by modulation of the auxiliary power. Steady-state current drive is the most demanding requirement, so this has driven the choice of the ITER current drive and heating systems.

  19. Experimental And Theoretical Determination Of Forming Limit Curve

    Directory of Open Access Journals (Sweden)

    Adamus J.

    2015-09-01

    Full Text Available The paper presents a method for determining forming limit curves based on a combination of experiments with finite element analysis. In the experiment a set of 6 samples with different geometries underwent plastic deformation in stretch forming till the appearance of fracture. The heights of the stamped parts at fracture moment were measured. The sheet - metal forming process for each sample was numerically simulated using Finite Element Analysis (FEA. The values of the calculated plastic strains at the moment when the simulated cup reaches the height of the real cup at fracture initiation were marked on the FLC. FLCs for stainless steel sheets: ASM 5504, 5596 and 5599 have been determined. The resultant FLCs are then used in the numerical simulations of sheet - metal forming. A comparison between the strains in the numerically simulated drawn - parts and limit strains gives the information if the sheet - metal forming process was designed properly.

  20. A Solid-State Fault Current Limiting Device for VSC-HVDC Systems

    Science.gov (United States)

    Larruskain, D. Marene; Zamora, Inmaculada; Abarrategui, , Oihane; Iturregi, Araitz

    2013-08-01

    Faults in the DC circuit constitute one of the main limitations of voltage source converter VSC-HVDC systems, as the high fault currents can damage seriously the converters. In this article, a new design for a fault current limiter (FCL) is proposed, which is capable of limiting the fault current as well as interrupting it, isolating the DC grid. The operation of the proposed FCL is analysed and verified with the most usual faults that can occur in overhead lines.

  1. Modeling space-charge-limited currents in organic semiconductors: Extracting trap density and mobility

    KAUST Repository

    Dacuña, Javier

    2011-11-28

    We have developed and have applied a mobility edge model that takes drift and diffusion currents to characterize the space-charge-limited current in organic semiconductors into account. The numerical solution of the drift-diffusion equation allows the utilization of asymmetric contacts to describe the built-in potential within the device. The model has been applied to extract information of the distribution of traps from experimental current-voltage measurements of a rubrene single crystal from Krellner showing excellent agreement across several orders of magnitude in the current. Although the two contacts are made of the same metal, an energy offset of 580 meV between them, ascribed to differences in the deposition techniques (lamination vs evaporation) was essential to correctly interpret the shape of the current-voltage characteristics at low voltage. A band mobility of 0.13cm 2V-1s-1 for holes is estimated, which is consistent with transport along the long axis of the orthorhombic unit cell. The total density of traps deeper than 0.1 eV was 2.2×1016cm -3. The sensitivity analysis and error estimation in the obtained parameters show that it is not possible to accurately resolve the shape of the trap distribution for energies deeper than 0.3 eV or shallower than 0.1 eV above the valence-band edge. The total number of traps deeper than 0.3 eV, however, can be estimated. Contact asymmetry and the diffusion component of the current play an important role in the description of the device at low bias and are required to obtain reliable information about the distribution of deep traps. © 2011 American Physical Society.

  2. New Experimental Limit on Photon Hidden-Sector Paraphoton Mixing

    CERN Document Server

    Afanasev, A; Beard, K B; Biallas, G; Boyce, J; Minarni, M; Ramdon, R; Shinn, M; Slocum, P

    2008-01-01

    We report on the first results of a search for optical-wavelength photons mixing with hypothetical hidden-sector paraphotons in the mass range between 10^-5 and 10^-2 electron volts for a mixing parameter greater than 10^-7. This was a generation-regeneration experiment using the "light shining through a wall" technique in which regenerated photons are searched for downstream of an optical barrier that separates it from an upstream generation region. The new limits presented here are approximately three times more sensitive to this mixing than the best previous measurement. The present results indicate no evidence for photon-paraphoton mixing for the range of parameters investigated.

  3. Experimental evidence for extreme dispersal limitation in tropical forest birds.

    Science.gov (United States)

    Moore, R P; Robinson, W D; Lovette, I J; Robinson, T R

    2008-09-01

    Movements of organisms between habitat remnants can affect metapopulation structure, community assembly dynamics, gene flow and conservation strategy. In the tropical landscapes that support the majority of global biodiversity and where forest fragmentation is accelerating, there is particular urgency to understand how dispersal across habitats mediates the demography, distribution and differentiation of organisms. By employing unique dispersal challenge experiments coupled with exhaustive inventories of birds in a Panamanian lacustrine archipelago, we show that the ability to fly even short distances (birds, and that this variation correlates strongly with species' extinction histories and current distributions across the archipelago. This extreme variation in flight capability indicates that species' persistence in isolated forest remnants will be differentially mediated by their respective dispersal abilities, and that corridors connecting such fragments will be essential for the maintenance of avian diversity in fragmented tropical landscapes.

  4. Remote forcing of subsurface currents and temperatures near the northern limit of the California Current System

    Science.gov (United States)

    Engida, Zelalem; Monahan, Adam; Ianson, Debby; Thomson, Richard E.

    2016-10-01

    Local and remote wind forcing of upwelling along continental shelves of coastal upwelling regions play key roles in driving biogeochemical fluxes, including vertical net fluxes of carbon and nutrients. These fluxes are responsible for high primary productivity, which in turn supports a lucrative fishery in these regions. However, the relative contributions of local versus remote wind forcing are not well quantified or understood. We present results of coherence analyses between currents at a single mooring site (48.5°N, 126°W) in the northern portion of the California Current System (CalCS) from 1989 to 2008 and coincident time series of North America Regional Reanalysis (NARR) 10 m wind stress within the CalCS (36-54°N, 120-132°W). The two-decade-long current records from the three shallowest depths (35, 100, and 175 m) show a remote response to winds from south as far as 36°N. In contrast, only temperatures at the deepest depth (400 m) show strong coherences with remote winds. Weaker local wind influence is observed in both the currents and 400 m temperatures but is mostly due to the large spatial coherence within the wind field itself. Lack of coherence between distal winds and the 400 m currents suggests that the temperature variations at that depth are driven by vertical motion resulting from poleward travelling coastal trapped waves (CTWs). Understanding the effects of remote forcing in coastal upwelling regions is necessary for determining the occurrence and timing of extreme conditions in coastal oceans, and their subsequent impact on marine ecosystems.

  5. Ion Trap Quantum Computers: Performance Limits and Experimental Progress

    Science.gov (United States)

    Hughes, Richard

    1998-03-01

    In a quantum computer information would be represented by the quantum mechanical states of suitable atomic-scale systems. (A single bit of information represented by a two-level quantum system is known as a qubit.) This notion leads to the possibility of computing with quantum mechanical superpositions of numbers ("quantum parallelism"), which for certain problems would make Quantum/quantum.html>quantum computation very much more efficient than classical computation. The possibility of rapidly factoring the large integers used in public-key cryptography is an important example. (Public key cryptosystems derive their security from the difficuty of factoring, and similar problems, with conventional computers.) Quantum computational hardware development is in its infancy, but an experimental study of quantum computation with laser-cooled trapped calcium ions that is under way at Los Alamos will be described. One of the pricipal obstacles to practical quantum computation is the inevitable loss of quantum coherence of the complex quantum states involved. The results of a theoretical analysis showing that quantum factoring of small integers should be possible with trapped ions will be presented. The prospects for larger-scale computations will be discussed.

  6. ADVANTAGES AND THERMODYNAMIC LIMITATIONS OF THE EXPERIMENTAL SORPTION ISOSTERIC METHOD

    Directory of Open Access Journals (Sweden)

    FARID B. CORTÉS

    2013-01-01

    Full Text Available Una revisión de las ventajas y las limitaciones termodinámicas presentes en el método experimental sorción isostérica (SIM muestra que el SIM no garantiza una cantidad adsorbida constante. Las isósteras calculadas que consideran comportamiento de gas ideal muestran que en el SIM la masa de gas en el volumen muerto del sistema al incrementar la presión de equilibrio debido a los materiales desorbidos. El SIM es útil y efectivo para obtener datos termodinámicos de alta precisión para la sorción de gases en materiales micro y nanoporosos a bajas presiones y temperaturas. Por el contrario, cuando la presión y la temperatura son altas la desorción no es despreciable, por lo tanto el SIM no es aplicable. Los errores en los cálculos del calor isostérico usando SIM pueden ser reducidos usando procedimientos experimentales tradicionales como las isobaras e isotermas de adsorción para generar las isósteras a altas presiones y temperaturas. Como alternativa, correcciones por presión y temperatura, o un experimento que, después de cada incremento de temperatura permita a la dosis de gas compensar la masa desorbida, garantizaría una cantidad adsorbida constante y, por consiguiente, un comportamiento isostérico mediante medidas directas.

  7. Experimental study of blockage of monochromatic waves by counter currents

    NARCIS (Netherlands)

    Suastika, I.K.

    1999-01-01

    Blockage of waves by a current can occur if waves are propagating on a spatially varying opposing current in which the velocity is increasing in the wave propagation direction. The ongoing waves become shorter and steeper while they are propagating against the current. Blocking occurs at the

  8. Experimental Study on Current-Driven Domain Wall Motion

    Science.gov (United States)

    Ono, T.; Yamaguchi, A.; Tanigawa, H.; Yano, K.; Kasai, S.

    2006-06-01

    Current-driven domain wall (DW) motion for a well-defined single DW in a micro-fabricated magnetic wire with submicron width was investigated by real-space observation with magnetic force microscopy. Magnetic force microscopy visualizes that a single DW introduced in a wire is displaced back and forth by positive and negative pulsed-current, respectively. Effect of the Joule heating, reduction of the threshold current density by shape control, and magnetic ratchet effect are also presented.

  9. Series transformer based diode-bridge-type solid state fault current limiter

    Institute of Scientific and Technical Information of China (English)

    Amir HEIDARY; Hamid RADMANESH; Seyed Hamid FATHI; G B GHAREHPETIAN

    2015-01-01

    We propose a novel series transformer based diode-bridge-type solid state fault current limiter (SSFCL). To control the fault current, a series RLC branch is connected to the secondary side of an isolation series transformer. Based on this RLC branch, two current limiting modes are created. In the first mode, R and C are bypassed via a paralleled power electronic switch (insulated-gate bipolar transistor, IGBT) and L remains connected to the secondary side of the transformer as a DC reactor. In the second mode, the series reactor impedance is not enough to limit the fault current. In this case, the fault current can be con-trolled by selecting a proper on-off duration of the parallel IGBT, across the series damping resistor (R) and capacitor, which inserts high impedance into the line to limit the fault current. Then, by controlling the magnitude of the DC reactor current, the fault current is reduced and the voltage of the point of common coupling (PCC) is kept at an acceptable level. In addition, in the new SSFCL, the series RC branch, connected in parallel with the IGBT, serves as a snubber circuit for decreasing the transient recovery voltage (TRV) of the IGBT during on-off states. Therefore, the power quality indices can be improved. The measure-ment results of a built prototype are presented to support the simulation and theoretical studies. The proposed SSFCL can limit the fault current without any delay and successfully smooth the fault current waveform.

  10. A double-stage start-up structure to limit the inrush current used in current mode charge pump

    Science.gov (United States)

    Cong, Liu; Xinquan, Lai; Hanxiao, Du; Yuan, Chi

    2016-06-01

    A double-stage start-up structure to limit the inrush current used in current-mode charge pump with wide input range, fixed output and multimode operation is presented in this paper. As a widely utilized power source implement, a Li-battery is always used as the power supply for chips. Due to the internal resistance, a potential drop will be generated at the input terminal of the chip with an input current. A false shut down with a low supply voltage will happen if the input current is too large, leading to the degradation of the Li-battery's service life. To solve this problem, the inrush current is limited by introducing a new start-up state. All of the circuits have been implemented with the NUVOTON 0.6 μm CMOS process. The measurement results show that the inrush current can be limited below 1 A within all input supply ranges, and the power efficiency is higher than the conventional structure. Project supported by the National Natural Science Foundation of China (No. 61106026).

  11. Experimental study of the dynamics of a thin current sheet

    Science.gov (United States)

    Gekelman, W.; DeHaas, T.; Van Compernolle, B.; Daughton, W.; Pribyl, P.; Vincena, S.; Hong, D.

    2016-05-01

    Many plasmas in natural settings or in laboratory experiments carry currents. In magnetized plasmas the currents can be narrow field-aligned filaments as small as the electron inertial length ≤ft(\\tfrac{c}{{ω }pe}\\right) in the transverse dimension or fill the entire plasma column. Currents can take the form of sheets, again with the transverse dimension the narrow one. Are laminar sheets of electric current in a magnetized plasma stable? This became an important issue in the 1960s when current-carrying plasmas became key in the quest for thermonuclear fusion. The subject is still under study today. The conditions necessary for the onset for tearing are known, the key issue is that of the final state. Is there a final state? One possibility is a collection of stable tubes of current. On the other hand, is the interaction between the current filaments which are the byproduct endless, or does it go on to become chaotic? The subject of three-dimensional current systems is intriguing, rich in a variety of phenomena on multiple scale sizes and frequencies, and relevant to fusion studies, solar physics, space plasmas and astrophysical phenomena. In this study a long (δz = 11 m) and narrow (δx = 1 cm, δy = 20 cm) current sheet is generated in a background magnetoplasma capable of supporting Alfvén waves. The current is observed to rapidly tear into a series of magnetic islands when viewed in a cross-sectional plane, but they are in essence three-dimensional flux ropes. At the onset of the current, magnetic field line reconnection is observed between the flux ropes. The sheet on the whole is kink-unstable, and after kinking exhibits large-scale, low-frequency (f ≪ f ci ) rotation about the background field with an amplitude that grows with distance from the source of the current. Three-dimensional data of the magnetic and electric fields is acquired throughout the duration of the experiment and the parallel resistivity is derived from it. The parallel

  12. As it happens: current directions in experimental evolution.

    Science.gov (United States)

    Bataillon, Thomas; Joyce, Paul; Sniegowski, Paul

    2013-02-23

    Recent decades have seen a significant rise in studies in which evolution is observed and analysed directly-as it happens-under replicated, controlled conditions. Such 'experimental evolution' approaches offer a degree of resolution of evolutionary processes and their underlying genetics that is difficult or even impossible to achieve in more traditional comparative and retrospective analyses. In principle, experimental populations can be monitored for phenotypic and genetic changes with any desired level of replication and measurement precision, facilitating progress on fundamental and previously unresolved questions in evolutionary biology. Here, we summarize 10 invited papers in which experimental evolution is making significant progress on a variety of fundamental questions. We conclude by briefly considering future directions in this very active field of research, emphasizing the importance of quantitative tests of theories and the emerging role of genome-wide re-sequencing.

  13. Self-rehealing characteristics of a sodium current limiter and its over current coordination for low voltage distribution systems; Natoriumu (Na) genryu soshi no jiko fukkyu tokusei to teiatsu haiden kairo oyo ni okeru kadenryu kyocho

    Energy Technology Data Exchange (ETDEWEB)

    Wada, Y.; Hamano, S.; Mori, T. [Mitsubishi Electric Corp., Tokyo (Japan)

    1994-07-20

    As one of the short circuits protection techniques in a power circuit, there is a technique called the current-limiting breaking. When a short circuit current commences to flow after a short circuit occurs, this technique limits and breaks this current under a certain value by some measures before this current reaches to the crest value. There is a current-limiting fuse in the best known one as a functional element doing the current-limiting breaking. However in case of a current-limiting fuse, when an element is fused off, because a current can not be flowed, it has to be replaced. As a new element to eliminate this defect and moreover with a current-limiting function, a self-rehealing type current-limiting element possessing the alkaline metal, Na as an element has been developed. In this report, as for this element called Na current-limiting element, together with elucidating a rehealing process after the current-limiting action experimentally in detail, an overcurrent coordination is investigated when this element is applied to a main circuit of the control center, which is one of the low voltage distribution systems. 5 refs., 8 figs., 1 tab.

  14. A micro-power LDO with piecewise voltage foldback current limit protection

    Institute of Scientific and Technical Information of China (English)

    Wei Hailong; Liu Youbao; Guo Zhongjie; Liao Xue

    2012-01-01

    To achieve a constant current limit,low power consumption and high driving capability,a micro-power LDO with a piecewise voltage-foldback current-limit circuit is presented.The current-limit threshold is dynamically adjusted to achieve a maximum driving capability and lower quiescent current of only 300 nA.To increase the loop stability of the proposed LDO,a high impedance transconductance buffer under a micro quiescent current is designed for splitting the pole that exists at the gate of the pass transistor to the dominant pole,and a zero is designed for the purpose of the second pole phase compensation.The proposed LDO is fabricated in a BiCMOS process.The measurement results show that the short-circuit current of the LDO is 190 mA,the constant limit current under a high drop-out voltage is 440 mA,and the maximum load current under a low drop-out voltage is up to 800 mA.In addition,the quiescent current of the LDO is only 7 μA,the load regulation is about 0.56% on full scale,the line regulation is about 0.012%/V,the PSRR at 120 Hz is 58 dB and the drop-out voltage is only 70 mV when the load current is 250 mA.

  15. Superconducting technology for overcurrent limiting in a 25 kA current injection system

    Science.gov (United States)

    Heydari, Hossein; Faghihi, Faramarz; Sharifi, Reza; Poursoltanmohammadi, Amir Hossein

    2008-09-01

    Current injection transformer (CIT) systems are within the major group of the standard type test of high current equipment in the electrical industry, so their performance becomes very important. When designing high current systems, there are many factors to be considered from which their overcurrent protection must be ensured. The output of a CIT is wholly dependent on the impedance of the equipment under test (EUT). Therefore current flow beyond the allowable limit can occur. The present state of the art provides an important guide to developing current limiters not only for the grid application but also in industrial equipment. This paper reports the state of the art in the technology available that could be developed into an application of superconductivity for high current equipment (CIT) protection with no test disruption. This will result in a greater market choice and lower costs for equipment protection solutions, reduced costs and improved system reliability. The paper will also push the state of the art by using two distinctive circuits, closed-core and open-core, for overcurrent protection of a 25 kA CIT system, based on a flux-lock-type superconducting fault current limiter (SFCL) and magnetic properties of high temperature superconducting (HTS) elements. An appropriate location of the HTS element will enhance the rate of limitation with the help of the magnetic field generated by the CIT output busbars. The calculation of the HTS parameters for overcurrent limiting is also performed to suit the required current levels of the CIT.

  16. Current limiting characteristics of transformer type SFCL with coupled secondary windings according to its winding direction

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Sung Hun [Dept. of Electrical Engineering, Soongsil University, Seoul (Korea, Republic of); Han, Tae Hee [Dept. of Aero Materials Engineering, Jungwon University, Goesan (Korea, Republic of)

    2017-06-15

    In this paper, the current limiting characteristics of the transformer type superconducting fault current limiter (SFCL) with the two coupled secondary windings due to its winding direction were analyzed. To analyze the dependence of transient fault current limiting characteristics on the winding direction of the additional secondary winding, the fault current limiting tests of the SFCL with an additional secondary winding, wound as subtractive polarity winding and additive polarity winding, were carried out. The time interval of quench occurrence between two superconducting elements comprising the transformer type SFCL with the additional secondary winding was confirmed to be affected by the winding direction of the additional secondary winding. In case of the subtractive polarity winding of the additional secondary winding, the time interval of the quench occurrence in two superconducting elements was shorter than the case of the additive polarity winding.

  17. Charge Exchange Effect on Space-Charge-Limited Current Densities in Ion Diode

    Institute of Scientific and Technical Information of China (English)

    石磊

    2002-01-01

    The article theoretically studied the charge-exchange effects on space charge limited electron and ion current densities of non-relativistic one-dimensional slab ion diode, and compared with those of without charge exchange.

  18. Estimating Heat and Mass Transfer Processes in Green Roof Systems: Current Modeling Capabilities and Limitations (Presentation)

    Energy Technology Data Exchange (ETDEWEB)

    Tabares Velasco, P. C.

    2011-04-01

    This presentation discusses estimating heat and mass transfer processes in green roof systems: current modeling capabilities and limitations. Green roofs are 'specialized roofing systems that support vegetation growth on rooftops.'

  19. Diabetes Mellitus and Cardiovascular Prevention: The Role and the Limitations of Currently Available Antiplatelet Drugs

    Directory of Open Access Journals (Sweden)

    A. Tufano

    2011-01-01

    This paper reviews the role of currently available antiplatelet drugs in primary and secondary prevention of vascular events in diabetic patients and the limitations of these drugs, and it discusses the role of novel and more potent antiplatelets and of new agents currently under clinical development.

  20. Experimental Study on Current Decay Characteristics of Persistent Current HTS Magnet by Alternating Magnetic Field

    Science.gov (United States)

    Park, Young Gun; Lee, Chang Young; Hwang, Young Jin; Lee, Woo Seung; Lee, Jiho; Jo, Hyun Chul; Chung, Yoon Do; Ko, Tae Kuk

    This paper deals with a current decay characteristics of a high temperature superconducting (HTS) magnet operated in persistent current mode (PCM). In superconducting synchronous machine applications such as linear synchronous motor (LSM), the superconducting coil is designed to operate in the PCM to obtain steady magnetic field with DC transport current. This superconducting magnet operates on a direct current, but it can be exposed to alternating magnetic field due to the armature winding. When the magnet is subjected to an external time-varying magnetic field, it is possible to result in a decay of the current in PCM system due to AC loss. In this research, a PCM system with armature coil which generates time-varying magnetic field was fabricated to verify current decay characteristics by external alternating magnetic field. The current decay rate was measured by using a hall sensor as functions of amplitude and frequency of armature coil.

  1. InP Gunn Diodes with Current Limiting Contact for High Efficiency Gunn Oscillators

    Science.gov (United States)

    Kim, Mi-Ra; Rhee, Jin-Koo; Lee, Chang-Woo; Chae, Yeon-Sik; Choi, Jae-Hyun; Kim, Wan-Joo

    We fabricated and examined current limiting effect for InP Gunn diodes with stable depletion layer mode operation of diodes for high efficiency Gunn oscillators. Current limiting at the cathode was achieved by a shallow Schottky barrier at the interface. We discussed fabrication procedure, the results for negative differential resistance and rf tests for InP Gunn diodes. It was shown that the fabricated Gunn diodes have the output power of 10.22dBm at a frequency of 90.13GHz. Its input voltage and corresponding current were 8.55V and 252mA, respectively.

  2. A Revised Experimental Upper Limit on the Electric Dipole Moment of the Neutron

    CERN Document Server

    Pendlebury, J  M; Ayres, N J; Baker, C A; Ban, G; Bison, G; Bodek, K; Burghoff, M; Geltenbort, P; Green, K; Griffith, W C; van der Grinten, M; Grujic, Z D; Harris, P G; Helaine, V; Iaydjiev, P; Ivanov, S N; Kasprzak, M; Kermaidic, Y; Kirch, K; Koch, H-C; Komposch, S; Kozela, A; Krempel, J; Lauss, B; Lefort, T; Lemiere, Y; May, D J R; Musgrave, M; Musgrave, M; Naviliat-Cuncic, O; Piegsa, F M; Pignol, G; Prashanth, P N; Quéméner, G; Rawlik, M; Rebreyend, D; Richardson, J D; Ries, D; Roccia, S; Rozpedzik, D; Schnabel, A; Schmidt-Wellenburg, P; Severijns, N; Shiers, D; Thorne, J A; Weis, A; Winston, O  J; Wursten, E; Zejma, J; Zsigmond, G

    2015-01-01

    We present for the first time a detailed and comprehensive analysis of the experimental results that set the current world sensitivity limit on the magnitude of the electric dipole moment (EDM) of the neutron. We have extended and enhanced our earlier analysis to include recent developments in the understanding of the effects of gravity in depolarizing ultracold neutrons (UCN); an improved calculation of the spectrum of the neutrons; and conservative estimates of other possible systematic errors, which are also shown to be consistent with more recent measurements undertaken with the apparatus. We obtain a net result of $d_\\mathrm{n} = -0.21 \\pm 1.82 \\times10^{-26}$ $e$cm, which may be interpreted as a slightly revised upper limit on the magnitude of the EDM of $3.0 \\times10^{-26}$ $e$cm (90% CL) or $ 3.6 \\times10^{-26}$ $e$cm (95% CL). This paper is dedicated by the remaining authors to the memory of Prof. J. Michael Pendlebury.

  3. Over-limiting Current and Control of Dendritic Growth by Surface Conduction in Nanopores

    CERN Document Server

    Han, Ji-Hyung; Bai, Peng; Bazant, Martin Z

    2014-01-01

    Understanding over-limiting current (faster than diffusion) is a long-standing challenge in electrochemistry with applications in desalination and energy storage. Known mechanisms involve either chemical or hydrodynamic instabilities in unconfined electrolytes. Here, it is shown that over-limiting current can be sustained by surface conduction in nano pores, without any such instabilities, and used to control dendritic growth during electrodeposition. Copper electrode posits are grown in anodized aluminum oxide membranes with polyelectrolyte coatings to modify the surface charge. At low currents, uniform electroplating occurs, unaffected by surface modification due to thin electric double layers, but the morphology changes dramatically above the limiting current. With negative surface charge, growth is enhanced along the nanopore surfaces, forming surface dendrites and nanotubes behind a deionization shock. With positive surface charge, dendrites avoid the surfaces and are either guided along the nanopore cen...

  4. Wall conditioning for ITER: Current experimental and modeling activities

    Energy Technology Data Exchange (ETDEWEB)

    Douai, D., E-mail: david.douai@cea.fr [CEA, IRFM, Association Euratom-CEA, 13108 St. Paul lez Durance (France); Kogut, D. [CEA, IRFM, Association Euratom-CEA, 13108 St. Paul lez Durance (France); Wauters, T. [LPP-ERM/KMS, Association Belgian State, 1000 Brussels (Belgium); Brezinsek, S. [FZJ, Institut für Energie- und Klimaforschung Plasmaphysik, 52441 Jülich (Germany); Hagelaar, G.J.M. [Laboratoire Plasma et Conversion d’Energie, UMR5213, Toulouse (France); Hong, S.H. [National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Lomas, P.J. [CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom); Lyssoivan, A. [LPP-ERM/KMS, Association Belgian State, 1000 Brussels (Belgium); Nunes, I. [Associação EURATOM-IST, Instituto de Plasmas e Fusão Nuclear, 1049-001 Lisboa (Portugal); Pitts, R.A. [ITER International Organization, F-13067 St. Paul lez Durance (France); Rohde, V. [Max-Planck-Institut für Plasmaphysik, 85748 Garching (Germany); Vries, P.C. de [ITER International Organization, F-13067 St. Paul lez Durance (France)

    2015-08-15

    Wall conditioning will be required in ITER to control fuel and impurity recycling, as well as tritium (T) inventory. Analysis of conditioning cycle on the JET, with its ITER-Like Wall is presented, evidencing reduced need for wall cleaning in ITER compared to JET–CFC. Using a novel 2D multi-fluid model, current density during Glow Discharge Conditioning (GDC) on the in-vessel plasma-facing components (PFC) of ITER is predicted to approach the simple expectation of total anode current divided by wall surface area. Baking of the divertor to 350 °C should desorb the majority of the co-deposited T. ITER foresees the use of low temperature plasma based techniques compatible with the permanent toroidal magnetic field, such as Ion (ICWC) or Electron Cyclotron Wall Conditioning (ECWC), for tritium removal between ITER plasma pulses. Extrapolation of JET ICWC results to ITER indicates removal comparable to estimated T-retention in nominal ITER D:T shots, whereas GDC may be unattractive for that purpose.

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

    Science.gov (United States)

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

    2016-12-01

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

  6. Experimental investigation of current free double layers in helicon plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Sahu, B. B. [Department of Applied Sciences and Humanities, Dronacharya College of Engineering, Gurgaon 123506 (India); Tarey, R. D. [Department of Physics, Indian Institute of Technology, New Delhi 110016 (India); Ganguli, A. [Centre for Energy Studies, Indian Institute of Technology, New Delhi 110016 (India)

    2014-02-15

    The paper presents investigations of current free double layer (CFDL) that forms in helicon plasmas. In contrast to the other work reporting on the same subject, in the present investigations the double layer (DL) forms in a mirror-like magnetic field topology. The RF compensated Langmuir probe measurements show multiple DLs, which are in connection with, the abrupt fall of densities along with potential drop of about 24 V and 18 V. The DLs strengths (e ΔV{sub p})/(k T{sub e}) are about 9.5 and 6, and the corresponding widths are about 6 and 5 D lengths. The potential drop is nearly equal to the thermal anisotropies between the two plasma regions forming the DL, which is present in the plateau region of mirror, unlike the earlier studies on the DL formation in the region of strong gradients in the magnetic field. Also, it presents a qualitative discussion on the mechanism of DL formation.

  7. Multi-Soft gluon limits and extended current algebras at null-infinity

    CERN Document Server

    McLoughlin, Tristan

    2016-01-01

    In this note we consider aspects of the current algebra interpretation of multi-soft limits of tree-level gluon scattering amplitudes in four dimensions. Building on the relation between a positive helicity gluon soft-limit and the Ward identity for a level-zero Kac-Moody current, we use the double-soft limit to define the Sugawara energy-momentum tensor and, by using the triple- and quadruple-soft limits, show that it satisfies the correct OPEs for a CFT. We study the resulting Knizhnik-Zamolodchikov equations and show that they hold for positive helicity gluons in MHV amplitudes. Turning to the sub-leading soft-terms we define a one-parameter family of currents whose Ward identities correspond to the universal tree-level sub-leading soft-behaviour. We compute the algebra of these currents formed with the leading currents and amongst themselves. Finally, by parameterising the ambiguity in the double-soft limit for mixed helicities, we introduce a non-trivial OPE between the holomorphic and anti-holomorphic c...

  8. Improving Transient Recovery voltage of circuit breaker using Fault Current Limiter

    Directory of Open Access Journals (Sweden)

    Amir Heidary

    2012-12-01

    Full Text Available This study investigates influence of Fault Current Limiter (FCL on short-circuits current level of substation bus bar splitter circuit breaker and its TRV. An approach for TRV evaluation is developed and applied for proposed power system as shown in this study. FCL circuit is connected to the power system in order to limit TRV. The limiter circuit consists of two equal windings which are turned around unique magnetic core. One of the windings is connected in series with the power system network and the other is connected to the network via series capacitor and power electronic switches. During normal operating condition, both tyristors are in on state and current of the primary and secondary windings are equal. This causes zero impedance of the limiter. During fault, faults current cause the power electronic switch to turn off which increases the limiter impedance. By increasing the limiter impedance, amplitude of TRV decreases substantially. The novel method presented in this study is a cheap and successful scheme.

  9. Safety and efficacy of transcranial direct current stimulation in acute experimental ischemic stroke.

    Science.gov (United States)

    Peruzzotti-Jametti, Luca; Cambiaghi, Marco; Bacigaluppi, Marco; Gallizioli, Mattia; Gaude, Edoardo; Mari, Silvia; Sandrone, Stefano; Cursi, Marco; Teneud, Luis; Comi, Giancarlo; Musco, Giovanna; Martino, Gianvito; Leocani, Letizia

    2013-11-01

    Transcranial direct current stimulation is emerging as a promising tool for the treatment of several neurological conditions, including cerebral ischemia. The therapeutic role of this noninvasive treatment is, however, limited to chronic phases of stroke. We thus ought to investigate whether different stimulation protocols could also be beneficial in the acute phase of experimental brain ischemia. The influence of both cathodal and anodal transcranial direct current stimulation in modifying brain metabolism of healthy mice was first tested by nuclear magnetic resonance spectroscopy. Then, mice undergoing transient proximal middle cerebral artery occlusion were randomized and treated acutely with anodal, cathodal, or sham transcranial direct current stimulation. Brain metabolism, functional outcomes, and ischemic lesion volume, as well as the inflammatory reaction and blood brain barrier functionality, were analyzed. Cathodal stimulation was able, if applied in the acute phase of stroke, to preserve cortical neurons from the ischemic damage, to reduce inflammation, and to promote a better clinical recovery compared with sham and anodal treatments. This finding was attributable to the significant decrease of cortical glutamate, as indicated by nuclear magnetic resonance spectroscopy. Conversely, anodal stimulation induced an increase in the postischemic lesion volume and augmented blood brain barrier derangement. Our data indicate that transcranial direct current stimulation exerts a measurable neuroprotective effect in the acute phase of stroke. However, its timing and polarity should be carefully identified on the base of the pathophysiological context to avoid potential harmful side effects.

  10. Proposal of rectifier type superconducting fault current limiter with non-inductive reactor (SFCL)

    Science.gov (United States)

    Mohammad Salim, Khosru; Muta, Itsuya; Hoshino, Tsutomu; Nakamura, Taketsune; Yamada, Masato

    2004-03-01

    A rectifier type superconducting fault current limiter (SFCL) with non-inductive reactor has been proposed. The concept behind this SFCL is the appearance of high impedance during non-superconducting state of the coil. In a hybrid bridge circuit, two superconducting coils connected in anti-parallel: a trigger coil and a limiting coil. Both the coils are magnetically coupled with each other and have same number of turns. There is almost zero flux inside the core and therefore the total inductance is small during normal operation. At fault time when the trigger coil current reaches to a certain level, the trigger coil changes from superconducting state to normal state. This super-to-normal transition of the trigger coil changes the current ratio of the coils and therefore the flux inside the reactor is no longer zero. So, the equivalent impedance of both the coils increased thus limits the fault current. We have carried out computer simulation using EMTDC and observed the results. A preliminary experiment has already been performed using copper wired reactor with simulated super-to-normal transition resistance and magnetic switches. Both the simulation and preliminary experiment shows good results. The advantage of using hybrid bridge circuit is that the SFCL can also be used as circuit breaker. Two separate bridge circuit can be used for both trigger coil and the limiter coil. In such a case, the trigger coil can be shutdown immediately after the fault to reduce heat and thus reduce the recovery time. Again, at the end of fault when the SFCL needs to re-enter to the grid, turning off the trigger circuit in the two-bridge configuration the inrush current can be reduced. This is because the current only flows through the limiting coil. Another advantage of this type of SFCL is that no voltage sag will appear during load increasing time as long as the load current stays below the trigger current level.

  11. Realizing life-scalable experimental pyroclastic density currents

    Science.gov (United States)

    Cronin, S. J.; Lube, G.; Breard, E.; Jones, J.; Valentine, G.; Freundt, A.; Hort, M. K.; Bursik, M. I.

    2013-12-01

    Pyroclastic Density Currents (PDCs) - the most deadly threat from volcanoes - are extremely hot, ground-hugging currents of rock fragments and gas that descend slopes at hundreds of kilometers per hour. These hostile flows are impossible to internally measure, thus volcanologists are persistently blocked in efforts to realistically forecast their internal mechanics and hazards. Attempts to fill this gap via laboratory-scale experiments continue to prove difficult, because they usually mismatch the dynamic and kinematic scaling of real-world flows by several orders of magnitude. In a multi-institutional effort, the first large-scale pyroclastic flow generator that can synthesize repeatable hot high-energy gas-particle mixture flows in safety has been commissioned in New Zealand. The final apparatus stands 15 m high, consisting of a tower/elevator system; an instrumented hopper that can hold >6000 kg (or 3.2 m3) of natural volcanic materials, which can be discharged at a range of controlled rates onto an instrumented, variably inclinable (6-25°) glass-sided chute for examining the vertical profiles of PDCs in motion. The use of rhyolitic pyroclastic material from the 1800 AD Taupo Eruption (with its natural grain-size, sorting and shape characteristics) and gas ensures natural coupling between the solids and fluid phases. PDC analogues with runout of >15 meters and flow depths of 1.5-6 meters are created by generating variably heated falling columns of natural volcanic particles (50-1300 kg/s), dispersed and aerated to controlled particle densities between 3 and 60 vol.% at the base of the elevated hopper. The descending columns rapidly generate high-velocity flows (up to 14 m/s) once impacting on the inclined channel, reproducing many features of natural flows, including segregation into dense and dilute regimes, progressive aggradational and en masse deposition of particles and the development of high internal gas-pore-pressures during flow. The PDC starting

  12. Analysis and design of over-current limit control strategies applied in aeronautical power supplies

    Institute of Scientific and Technical Information of China (English)

    WANG Lin-bing; HE Xiang-ning

    2007-01-01

    Some Over-Current Limit Control strategies are analyzed and designed to meet the demands of high reliability and rapid dynamic response in the aeronautical power supply applications. The control schemes are both effective in DC-DC converters and DC-AC converters. Controller models are set up, and the over-current limit operation principles of analogy and digital control are analyzed too. An 800VA aeronautical power supply has been constructed to verify the performance of the proposed control strategy in various cases such as the sudden load change and the constant load. The analysis and experiments confirm the advantages of the proposed over-current limit strategies as follows: simple,effective and reliable.

  13. Modeling the Non Linear Behavior of a Magnetic Fault Current Limiter

    Directory of Open Access Journals (Sweden)

    P. R. Wilson

    2015-11-01

    Full Text Available Fault Current Limiters are used in a wide array of applications from small circuit protection at low power levels to large scale high power applications which require superconductors and complex control circuitry. One advantage of  passive fault current limiters (FCL is the automatic behavior that is dependent on the intrinsic properties of the circuit elements rather than on a complex feedback control scheme making this approach attractive for low cost applications and also where reliability is critical. This paper describes the behavioral modeling of a passive Magnetic FCL and its potential application in practical circuits.

  14. Two-dimensional relativistic space charge limited current flow in the drift space

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Y. L.; Chen, S. H., E-mail: chensh@ncu.edu.tw [Department of Physics, National Central University, Jhongli 32001, Taiwan (China); Koh, W. S. [A-STAR Institute of High Performance Computing, Singapore 138632 (Singapore); Ang, L. K. [Engineering Product Development, Singapore University of Technology and Design, Singapore 138682 (Singapore)

    2014-04-15

    Relativistic two-dimensional (2D) electrostatic (ES) formulations have been derived for studying the steady-state space charge limited (SCL) current flow of a finite width W in a drift space with a gap distance D. The theoretical analyses show that the 2D SCL current density in terms of the 1D SCL current density monotonically increases with D/W, and the theory recovers the 1D classical Child-Langmuir law in the drift space under the approximation of uniform charge density in the transverse direction. A 2D static model has also been constructed to study the dynamical behaviors of the current flow with current density exceeding the SCL current density, and the static theory for evaluating the transmitted current fraction and minimum potential position have been verified by using 2D ES particle-in-cell simulation. The results show the 2D SCL current density is mainly determined by the geometrical effects, but the dynamical behaviors of the current flow are mainly determined by the relativistic effect at the current density exceeding the SCL current density.

  15. Regge limit of R-current correlators in AdS supergravity

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, J.; Kotanski, J.; Mischler, A.M. [II. Inst. fuer Theoretische Physik, Univ. Hamburg (Germany); Schomerus, V. [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany)

    2009-08-15

    Four-point functions of R-currents are discussed within Anti-de Sitter supergravity. In particular, we compute Witten diagrams with graviton and gauge boson exchange in the high energy Regge limit. Assuming validity of the AdS/CFT correspondence, our results apply to R-current four-point functions of N=4 super Yang-Mills theory at strong coupling. (orig.)

  16. Surveillance of fetal arrhythmias in the outpatient setting: current limitations and call for action.

    Science.gov (United States)

    Freire, Grace

    2015-12-01

    Surveillance of fetal arrhythmias in the outpatient setting remains limited by lack of monitoring modalities. Despite technological advances made in the field of obstetrics, existing devices are not currently suitable to monitor fetal arrhythmias. In this report, the author describes the current and developing fetal heart rate monitoring technologies including the recent introduction of hand-held Doppler monitors for outpatient surveillance of fetal arrhythmias.

  17. Virtual Impedance Based Fault Current Limiters for Inverter Dominated AC Microgrids

    DEFF Research Database (Denmark)

    Lu, Xiaonan; Wang, Jianhui; Guerrero, Josep M.

    2017-01-01

    In this paper, a virtual impedance based fault current limiter (VI-FCL) is proposed for islanded microgrids comprised of multiple inverter interfaced distributed generators (DGs). Considering the increased fault current capability induced by high penetration of renewable energy sources (RESs), FC......, and the stability analysis in consideration of VI-FCLs is thereby studied. MATLAB/Simulink model comprised of three inverter-interfaced DGs is implemented to verify the feasibility of the proposed method....

  18. Superhydrophobic SAM Modified Electrodes for Enhanced Current Limiting Properties in Intrinsic Conducting Polymer Surge Protection Devices.

    Science.gov (United States)

    Jabarullah, Noor H; Verrelli, Emanuele; Mauldin, Clayton; Navarro, Luis A; Golden, Josh H; Madianos, Leonidas M; Kemp, Neil T

    2015-06-09

    Surface interface engineering using superhydrophobic gold electrodes made with 1-dodecanethiol self-assembled monolayer (SAM) has been used to enhance the current limiting properties of novel surge protection devices based on the intrinsic conducting polymer, polyaniline doped with methanesulfonic acid. The resulting devices show significantly enhanced current limiting characteristics, including current saturation, foldback, and negative differential effects. We show how SAM modification changes the morphology of the polymer film directly adjacent to the electrodes, leading to the formation of an interfacial compact thin film that lowers the contact resistance at the Au-polymer interface. We attribute the enhanced current limiting properties of the devices to a combination of lower contact resistance and increased Joule heating within this interface region which during a current surge produces a current blocking resistive barrier due to a thermally induced dedoping effect caused by the rapid diffusion of moisture away from this region. The effect is exacerbated at higher applied voltages as the higher temperature leads to stronger depletion of charge carriers in this region, resulting in a negative differential resistance effect.

  19. InGaAs-InP avalanche photodiodes with dark current limited by generation-recombination.

    Science.gov (United States)

    Zhao, Yanli; Zhang, Dongdong; Qin, Long; Tang, Qi; Wu, Rui Hua; Liu, Jianjun; Zhang, Youping; Zhang, Hong; Yuan, Xiuhua; Liu, Wen

    2011-04-25

    Separate absorption grading charge multiplication avalanche photodiodes (SAGCM APDs) are widely accepted in photon starved optical communication systems due to the presence of large photocurrent gain. In this work, we present a detailed analysis of dark currents of planar-type SAGCM InGaAs-InP APDs with different thicknesses of multiplication layer. The effect of the diffusion process, the generation-recombination process, the tunneling process and the multiplication process on the total leakage current is discussed. A new empirical formula has been established to predict the optimal multiplication layer thickness of SAGCM APDs with dark current limited by generation-recombination at multiplication gain of 8.

  20. An experimental study of secondary electron emission in the limit of low electron energy

    Science.gov (United States)

    Demidov, V. I.; Kaganovich, I. D.; Koepke, M. E.

    2013-09-01

    Study of secondary electron emission (SEE) from solid surfaces is important for many areas of science and technology, including but not limited to the formation of electron clouds in particle accelerators, plasma measurements by electrostatic probes and operation of Hall plasma thrusters. The measurements at low incident electron energy below 2eV are very challenging. The goal of this work is to measure SEE coefficient for molybdenum surface in contact with plasmas. In this study nearly mono-energetic electrons arising in plasma-chemical reactions like pair collisions of metastable atoms have been used for the measurements. Variation of the target voltage and measurement of the corresponding electron current from the mono-energetic electrons allows us to obtain the SEE coefficient. It is experimentally demonstrated that the coefficient is close to zero (less than 0.1) for clean targets and may have much higher value for contaminated targets with some absorbed gas on the surface. This work has been supported by DoE contract No. DE-SC0001939 and SPbGU.

  1. Limitations in bonding to dentin and experimental strategies to prevent bond degradation.

    Science.gov (United States)

    Liu, Y; Tjäderhane, L; Breschi, L; Mazzoni, A; Li, N; Mao, J; Pashley, D H; Tay, F R

    2011-08-01

    The limited durability of resin-dentin bonds severely compromises the lifetime of tooth-colored restorations. Bond degradation occurs via hydrolysis of suboptimally polymerized hydrophilic resin components and degradation of water-rich, resin-sparse collagen matrices by matrix metalloproteinases (MMPs) and cysteine cathepsins. This review examined data generated over the past three years on five experimental strategies developed by different research groups for extending the longevity of resin-dentin bonds. They include: (1) increasing the degree of conversion and esterase resistance of hydrophilic adhesives; (2) the use of broad-spectrum inhibitors of collagenolytic enzymes, including novel inhibitor functional groups grafted to methacrylate resins monomers to produce anti-MMP adhesives; (3) the use of cross-linking agents for silencing the activities of MMP and cathepsins that irreversibly alter the 3-D structures of their catalytic/allosteric domains; (4) ethanol wet-bonding with hydrophobic resins to completely replace water from the extrafibrillar and intrafibrillar collagen compartments and immobilize the collagenolytic enzymes; and (5) biomimetic remineralization of the water-filled collagen matrix using analogs of matrix proteins to progressively replace water with intrafibrillar and extrafibrillar apatites to exclude exogenous collagenolytic enzymes and fossilize endogenous collagenolytic enzymes. A combination of several of these strategies should result in overcoming the critical barriers to progress currently encountered in dentin bonding.

  2. Implementation of superconducting fault current limiter for flexible operation in the power substation

    Energy Technology Data Exchange (ETDEWEB)

    Song, Chong Suk, E-mail: chong_suk@korea.ac.kr [School of Electrical Engineering, Korea University, Anam dong, Seonbukgu, Seoul 136-713 (Korea, Republic of); Lee, Hansang [School of Railway and Electrical Engineering, Kyungil University, Hayang-eup, Gyeongsan-si, Gyeongsangbuk-do 712-701 (Korea, Republic of); Cho, Yoon-sung [Department of Electric and Energy Engineering, Catholic University of Daegu, Hayang-eup, Gyeongsan-si, Gyeongsangbuk-do 712-702 (Korea, Republic of); Suh, Jaewan [School of Electrical Engineering, Korea University, Anam dong, Seonbukgu, Seoul 136-713 (Korea, Republic of); Jang, Gilsoo, E-mail: gjang@korea.ac.kr [School of Electrical Engineering, Korea University, Anam dong, Seonbukgu, Seoul 136-713 (Korea, Republic of)

    2014-09-15

    Highlights: • The power load concentrated in load centers results in high levels of fault current. • This paper introduces a fault current reduction scheme using SFCLs in substations. • The SFCL is connected in parallel to the bus tie between the two busbars. • The fault current mitigation using SFCLs is verified through PSS/e simulations. - Abstract: The concentration of large-scale power loads located in the metropolitan areas have resulted in high fault current levels during a fault thereby requiring the substation to operate in the double busbar configuration mode. However, the double busbar configuration mode results in deterioration of power system reliability and unbalanced power flow in the adjacent transmission lines which may result in issues such as overloading of lines. This paper proposes the implementation of the superconducting fault current limiter (SFCL) to be installed between the two substation busbars for a more efficient and flexible operation of the substation enabling both single and double busbar configurations depending on the system conditions for guaranteeing power system reliability as well as fault current limitations. Case studies are being performed for the effectiveness of the SFCL installation and results are compared for the cases where the substation is operating in single and double busbar mode and with and without the installation of the SFCL for fault current mitigation.

  3. Theoretical and Experimental Study of Hopf Bifurcation and Limit Cycles of Railway Vehicle Hunting

    Institute of Scientific and Technical Information of China (English)

    Zeng Jing; Zhang Weihua; Shen Zhiyun

    1996-01-01

    The nonlinear hunting stability of railway vehicles is studied theoretically and experimentally in this paper. The Hopf bifurcation point is determined through calculating the eigenvalues of the system linearization equations incorporating with the golden cut method. The bifurcated limit cycles are computed by use of the shooting method to solve the boundary value problem of the system differential equations. Experimental validation to the numerical results is carricd out by utilizing the full scale roller test rig.

  4. Experimental quantum key distribution with simulated ground-to-satellite photon losses and processing limitations

    Science.gov (United States)

    Bourgoin, Jean-Philippe; Gigov, Nikolay; Higgins, Brendon L.; Yan, Zhizhong; Meyer-Scott, Evan; Khandani, Amir K.; Lütkenhaus, Norbert; Jennewein, Thomas

    2015-11-01

    Quantum key distribution (QKD) has the potential to improve communications security by offering cryptographic keys whose security relies on the fundamental properties of quantum physics. The use of a trusted quantum receiver on an orbiting satellite is the most practical near-term solution to the challenge of achieving long-distance (global-scale) QKD, currently limited to a few hundred kilometers on the ground. This scenario presents unique challenges, such as high photon losses and restricted classical data transmission and processing power due to the limitations of a typical satellite platform. Here we demonstrate the feasibility of such a system by implementing a QKD protocol, with optical transmission and full post-processing, in the high-loss regime using minimized computing hardware at the receiver. Employing weak coherent pulses with decoy states, we demonstrate the production of secure key bits at up to 56.5 dB of photon loss. We further illustrate the feasibility of a satellite uplink by generating a secure key while experimentally emulating the varying losses predicted for realistic low-Earth-orbit satellite passes at 600 km altitude. With a 76 MHz source and including finite-size analysis, we extract 3374 bits of a secure key from the best pass. We also illustrate the potential benefit of combining multiple passes together: while one suboptimal "upper-quartile" pass produces no finite-sized key with our source, the combination of three such passes allows us to extract 165 bits of a secure key. Alternatively, we find that by increasing the signal rate to 300 MHz it would be possible to extract 21 570 bits of a secure finite-sized key in just a single upper-quartile pass.

  5. Limiting Current of Oxygen Reduction on Gas-Diffusion Electrodes for Phosphoric Acid Fuel Cells

    DEFF Research Database (Denmark)

    Li, Qingfeng; Gang, Xiao; Hjuler, Hans Aage;

    1994-01-01

    Various models have been devoted to the operation mechanism of porous diffusion electrodes. They are, however, suffering from the lack of accuracy concerning the acid-film thickness on which they are based. In the present paper the limiting current density has been measured for oxygen reduction...... on polytetrafluorine-ethyl bonded gas-diffusion electordes in phosphoric acid with and without fluorinated additives. This provides an alternative to estimate the film thickness by combining it with the acid-adsorption measurements and the porosity analysis of the catalyst layer. It was noticed that the limiting...... expression for the limiting current density. The acid-film thickness estimated this way was found to be of 0.1 mum order of magnitude for the two types of electrodes used in phosphoric acid with and without fluorinated additives at 150-degrees-C....

  6. Analysis of the effects of asymmetric faults in three-phase superconducting inductive fault current limiters

    Science.gov (United States)

    Ferreira, R.; Pina, J. M.; Vilhena, N.; Arsénio, P.; Pronto, A. G.; Martins, J.

    2014-05-01

    Inductive fault current limiters of magnetic shielding type can be described in terms of the excursion in the plane defined by flux linked with primary and line current, and this methodology has been previously applied to single-phase devices. Practical applications, however, require three-phase limiters, which, for the sake of compactness, may be built by three legged cores, instead of three single phase units. This has the advantage of using well established methods of power transformers industry, but the performance of the devices depends on the type of fault, e.g. phase to ground or phase to phase. For instance, in a three legged core, a phase to ground fault affects healthy phases, and these are the most frequent faults in distribution grids, where such systems are envisaged. The effects of asymmetric faults are analysed in this paper, by means of measured excursions in the linked flux-current plane.

  7. Inrush Current Limitation in Wind Generators by SCR Based Soft-starter during grid connection

    Directory of Open Access Journals (Sweden)

    Sanjay Mishra

    2013-10-01

    Full Text Available High Inrush current & harmonics is a generic problem wind generators during grid connection.The designed SCR based soft-starter successfully limits the high inrush current during the connection of the wind-turbine system to the grid. The proposed SCR based soft starter using will be simulating in PSCAD on a three-phase induction generator. Expected results will show a significant reduction in high inrush current and smooth connection of the three phase induction generator to the grid with small impact on the power quality. A small-scale wind turbine coupled three phase induction generator is an attractive choice for an isolated grid hybrid power system in remote areas because of its low cost, compactness, ruggedness, high reliability, low inertia and ease in control. In this work, a SCR based soft starter for limiting the high inrush current during the connection of the small-scale wind turbine coupled three phase induction generator to an isolated weak grid has been proposed. Soft-starter is designed to reduce inrush current or surge in current while achieving a proper synchronism between the generator and the grid.

  8. Enhancement of transient stability using fault current limiter and braking resistor

    Energy Technology Data Exchange (ETDEWEB)

    Yagami, M.; Hiratsuka, Y. [Hokkaido Inst. of Technology, Sapporo, Hokkaido (Japan); Tamura, J. [Kitami Inst. of Technology, Kitami, Hokkaido (Japan)

    2006-07-01

    Replacement of aging substation equipment is needed in order to maintain the stability of electric power systems which are becoming increasingly interconnected. This paper addressed the issue of using fault current limiters (FCLs) as a means of limiting fault currents and enhancing the transient stability of a power system. FCL limits the fault current by generating an impedance when a fault occurs. The limiting impedance helps to increase generator output degraded by a fault, thus providing stabilization. However, FCLs installed in series with transmission lines can only be operated during the period from the fault occurrence to the fault clearing. Therefore, they cannot control the generator disturbances after the clearing of a fault. However, in the event of power failures, thyristor controlled braking resistors (TCBRs) can quickly control generator disturbances. Therefore, the authors proposed the use of both FCL and TCBR devices to enhance transient stability and damp the turbine shaft torsional oscillations. The effectiveness of both devices on suppression of the turbine shaft torsional oscillations was illustrated through simulations performed in EMTP/ATP considering three-lines-to-ground fault. It was shown that if both devices operate at the same bus, the stabilization control scheme can be carried out continuously and with flexibility from the fault occurrence instance, thereby effectively improving transient stability. 7 refs., 2 tabs., 10 figs.

  9. Experimental pain processing in individuals with cognitive impairment: current state of the science.

    Science.gov (United States)

    Defrin, Ruth; Amanzio, Martina; de Tommaso, Marina; Dimova, Violeta; Filipovic, Sasa; Finn, David P; Gimenez-Llort, Lydia; Invitto, Sara; Jensen-Dahm, Christina; Lautenbacher, Stefan; Oosterman, Joukje M; Petrini, Laura; Pick, Chaim G; Pickering, Gisele; Vase, Lene; Kunz, Miriam

    2015-08-01

    Cognitive impairment (CI) can develop during the course of ageing and is a feature of many neurological and neurodegenerative diseases. Many individuals with CI have substantial, sustained, and complex health care needs, which frequently include pain. However, individuals with CI can have difficulty communicating the features of their pain to others, which in turn presents a significant challenge for effective diagnosis and treatment of their pain. Herein, we review the literature on responsivity of individuals with CI to experimental pain stimuli. We discuss pain responding across a large number of neurological and neurodegenerative disorders in which CI is typically present. Overall, the existing data suggest that pain processing is altered in most individuals with CI compared with cognitively intact matched controls. The precise nature of these alterations varies with the type of CI (or associated clinical condition) and may also depend on the type of pain stimulation used and the type of pain responses assessed. Nevertheless, it is clear that regardless of the etiology of CI, patients do feel noxious stimuli, with more evidence for hypersensitivity than hyposensitivity to these stimuli compared with cognitively unimpaired individuals. Our current understanding of the neurobiological mechanisms underpinning these alterations is limited but may be enhanced through the use of animal models of CI, which also exhibit alterations in nociceptive responding. Further research using additional behavioural indices of pain is warranted. Increased understanding of altered experimental pain processing in CI will facilitate the development of improved diagnostic and therapeutic approaches for pain in individuals with CI.

  10. Current Limitations and Recommendations to Improve Testing for the Environmental Assessment of Endocrine Active Substances

    DEFF Research Database (Denmark)

    Coady, Katherine K; Biever, Ronald C; Denslow, Nancy D

    2016-01-01

    evaluate whether a chemical possesses endocrine activity and whether this activity can result in adverse outcomes either to humans or the environment. Current test systems include in silico, in vitro and in vivo techniques focused on detecting potential endocrine activity, and in vivo tests that collect...... apical data to detect possible adverse effects. These test systems are currently designed to robustly assess endocrine activity and/or adverse effects in the estrogen, androgen, and thyroid hormone signaling pathways; however, there are some limitations of current test systems for evaluating endocrine...... methods currently do not exist, and addressing key endocrine pathways of possible concern in addition to those associated with estrogen, androgen and thyroid signaling. This article is protected by copyright. All rights reserved....

  11. Setting occupational exposure limits in humans: contributions from the field of experimental psychology

    NARCIS (Netherlands)

    Smeets, M.A.M.; Kroeze, J.H.A.; Dalton, P.M.

    2006-01-01

    Psychophysical methods from the field of experimental psychology are evaluated for their utility in the derivation of occupational exposure limits (OELs) for volatile chemicals based on acute sensory irritation in humans. The lateralization threshold method, which involves the localization of trigem

  12. Experimental study and simulation of a micro-discharge with limited cathode area

    CERN Document Server

    Dufour, Thierry; Dussart, Remi; Pitchford, L C; Sadeghi, N; Lefaucheux, P; Kulsreshath, M; Ranson, P

    2016-01-01

    We report in this paper simulation results and experimental measurements to characterize a micro-discharge generated in a single micro cavity device operating in helium. By spatially limiting the cathode surface area using a dielectric layer, we demonstrate the ability of the micro-discharge to work in a steady-state abnormal glow regime. The physical properties of this regime are discussed.

  13. Review on Superconducting Fault Current Limiters%超导限流器综述

    Institute of Scientific and Technical Information of China (English)

    信赢

    2015-01-01

    This paper briefly recalls the scientific origin and R&D history of superconducting fault current limiters. The working princi-ple, generic structure, and equivalent circuitry of resistive type, saturated iron-core type, magnetic shield type, and bridge type super-conducting fault current limiters are introduced. The functional characteristics, technical advantages and disadvantages of resistive type and saturated iron-core type superconducting fault current limiters are analyzed and compared in detail. Real grid application examples of these two types of devices are presented. Discussing the application scope and prospect of superconducting fault current limiters, the paper points out that besides conventional fault current limiting functions, superconducting fault current limiters may become an indis-pensable device in grid integration of distributed renewable generations, and they will play an important role in upgrading power grids by reducing transmission loss and enhancing efficiency in the future.%概述了超导限流器的科学基础和发展历史,介绍了电阻型、饱和铁心型、磁屏蔽性和电桥型超导限流器的技术原理、基本结构和等效电路,详细分析和比较了电阻型和饱和铁心型超导限流器的性能特征、优点和缺点,以及其在实际电网挂网运行的案例。展望了超导限流器可能的应用范围及前景,指出除了传统观念上的短路故障限流作用之外,超导限流器未来可能成为可再生能源分布式发电并网的必要设备,在降低输电损耗和提高输送效率方面发挥重要作用。

  14. Research on a Fast-Closing Switch Based Fault Current Limiter with Series Compensation

    Institute of Scientific and Technical Information of China (English)

    CHEN Jin-xiang; ZOU Ji-yan; DONG En-yuan; SHI Jing

    2002-01-01

    A new type of fault current limiter (FCL) with series compensation based fast-closing switch is proposed. It is composed of a capacitor bank and a reactor in series.The main control component is a fast-closing switch connected in parallel with the capacitors, which is driven by the electromagnetic repulsion force. When fault occurs, the switch closes and bypasses the capacitors,and the fault is limited by the reactor then. Simulated analysis and experiments show that it is feasible to develop the FCL with low cost and high reliability. The effectiveness of transient stability for power system is evaluated by digital simulation.

  15. Impact and Limitations Deriving from Basel II within the Context of the Current Financial Crisis

    Directory of Open Access Journals (Sweden)

    Oana Miruna DĂNILĂ

    2012-06-01

    Full Text Available The Banking sector risk management framework, geared towards maintaining a solid capital adequacy level, has witnessed a permanent evolution, determined by the global economic and financial reality.Basel II has brought an improvement of the risk management framework by adding minimum capital levels corresponding to market and operational risk and by the introduction of internal rating models. However the current crisis has brought forward some adverse effects as well as limitations.This paper analyses the evolution of prudential rules and regulations introduced by Basel II and their impact on the banking system together with outlining certain limitations.

  16. Limitations of absolute current densities derived from the Semel & Skumanich method

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Semel and Skumanich proposed a method to obtain the absolute electric current density, |Jz|, without disambiguation of 180° in the transverse field directions. The advantage of the method is that the uncertainty in the determination of the ambiguity in the magnetic azimuth is removed. Here, we investigate the limits of the calculation when applied to a numerical MHD model. We have found that the combination of changes in the magnetic azimuth with vanishing horizontal field component leads to errors, where electric current densities are often strong. Where errors occur, the calculation gives |Jz| too small by factors typically 1.2 - 2.0.

  17. Currents, HF Radio-derived, Monterey Bay, 1 hr, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  18. Currents, HF Radio-derived, SF Bay, 1 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  19. Currents, HF Radio-derived, SF Bay Outlet, 1 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  20. Currents, HF Radio-derived, SF Bay Outlet, 1 hr, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  1. Currents, HF Radio-derived, Bodega Bay, 1 hr, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  2. Currents, HF Radio-derived, Bodega Bay, 1 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  3. Currents, HF Radio-derived, Ano Nuevo, 1 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  4. Currents, HF Radio-derived, Ano Nuevo, 1 hr, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 1 hour average of the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN EXPERIMENTAL...

  5. Experimental diabetes induced by alloxan and streptozotocin: The current state of the art.

    Science.gov (United States)

    Radenković, Miroslav; Stojanović, Marko; Prostran, Milica

    2016-01-01

    Diabetes mellitus is a chronic metabolic disorder with a high prevalence worldwide. Animal models of diabetes represent an important tool in diabetes investigation that helps us to avoid unnecessary and ethically challenging studies in human subjects, as well as to obtain a comprehensive scientific viewpoint of this disease. Although there are several methods through which diabetes can be induced, chemical methods of alloxan- and streptozotocin-induced diabetes represent the most important and highly preferable experimental models for this pathological condition. Therefore, the aim of this article was to review the current knowledge related to quoted models of diabetes, including to this point available information about mechanism of action, particular time- and dose-dependent protocols, frequent problems, as well as major limitations linked to laboratory application of alloxan and sterptozotocin in inducing diabetes. Given that diabetes is known to be closely associated with serious health consequences it is of fundamental importance that current animal models for induction of diabetes should be continuously upgraded in order to improve overall prevention, diagnosis and treatment of this pathological condition.

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

    DEFF Research Database (Denmark)

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

    2007-01-01

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

  7. Study of the Fast—Closing Switch Used for Fault Current Limiters in Power System

    Institute of Scientific and Technical Information of China (English)

    邹积岩; 陈金祥; 等

    2002-01-01

    This paper presents a new type of fault current limiter(FCL) based on fast-closing switch,which is composed of a capacitor bank and a reactor in series.The main control component is a fast-closing switch connected in parallel with the capactitors,which is drien by the electromagnetic repulsion force.It can response the order within 1 ms.When fault occurs,the switch closes and the capacitors are bypassed.and the fault current is limited by the reactor,Simulation analysis and experiment show that the electromagnetic repulsion force actuator can meet the demand of fast-closing switch,it is feasible to develop the FCL with low cost and high reliability.

  8. Current-limiting reactor based on high-T sub c superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bashkirov, Y.A.; Fleishman, L.S.; Patsayeve, T.Y.; Sobolev, A.N.P; Vdovin, A.B. (Krzhizhanovsky Power Engineering Inst., Leninsky prospect, 19, Moscow 117927 (SU))

    1991-03-01

    This paper deals with one of the possible applications of high-temperature superconductors in power devices with superconducting shields. The behavior was analyzed of a current-limiting reactor combining a high-T{sub c} shield and an iron core in an a.c. circuit. The model of the device was built comprising a stack of yttrium ceramic rings. The experiments with such a reactor confirmed the presence of nonlinear characteristics with transition from low to high impedance.

  9. Transformation of current limiting effect into varistor effect in tin dioxide based ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Bondarchuk, A N; Glot, A B [Universidad Tecnologica de la Mixteca, Huajuapan de Leon, Oaxaca, C.P. 69000 (Mexico)], E-mail: alexbond@mixteco.utm.mx

    2008-09-07

    The current limiting effect and its transformation into the varistor effect were found in SnO{sub 2}-Co{sub 3}O{sub 4}-Nb{sub 2}O{sub 5}-Cr{sub 2}O{sub 3} ceramics sintered at relatively low temperatures 1100-1200 {sup 0}C. Results of electrical measurements in oxidizing and inert atmosphere are explained in terms of the modified barrier model.

  10. Limiting current technique in the research of mass/heat transfer in nanofluid

    Science.gov (United States)

    Wilk, J.; Grosicki, S.

    2016-09-01

    In the paper the authors focused on the application of the electrochemical limiting diffusion current technique to the study of mass transfer in nanofluid flow. As mass and heat transfer are analogical phenomena, analysing mass transfer helps understand heat transfer processes in nanofluids. The paper begins with a short review of the available literature on the subject followed by the authors' results of mass transfer coefficient measurements and the conclusions concerning mass/heat transfer enhancement in nanofluids.

  11. Current meter data from moored current meter casts in the Northeast Pacific (limit - 180) from 12 June 1992 - 20 June 1994 (NODC Accession 9700237)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current meter data were collected using moored current meter casts in the Northeast Pacific (limit - 180) from June 12, 1992 to June 20, 1994. Data were submitted by...

  12. Current components data from current meters from the NE Pacific (limit-180) from 01 June 1954 to 01 June 1970 (NODC Accession 7601441)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current components data were collected from current meters in the NE Pacific (limit-180). Data were collected by the Japanese Hydrographic Office from 01 June 1954...

  13. Limiting current density in bis(trifluoromethylsulfonyl)amide-based ionic liquid for lithium batteries

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jun-Woo; Yoshida, Kazuki; Tachikawa, Naoki; Dokko, Kaoru; Watanabe, Masayoshi [Department of Chemistry and Biotechnology, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501 (Japan)

    2011-02-15

    The physicochemical and electrochemical properties of the binary ionic liquid (IL), lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) dissolved in N,N-diethyl-N-methyl-N-(2-methoxyethyl)ammonium bis(trifluoromethylsulfonyl)amide (DEMETFSA), were investigated. The ionic conductivity of the binary IL decreased with an increase in LiTFSA concentration. The self-diffusion coefficients of Li{sup +}, DEME{sup +}, and TFSA{sup -} dissolved in the IL were measured by using the pulsed-field-gradient spin-echo (PGSE) NMR method. The self-diffusion coefficient of each ionic species was also found to decrease with increasing concentration of LiTFSA. The limiting current density in the IL electrolyte was evaluated by chronoamperometry using symmetric Li vertical stroke IL vertical stroke Li cell. The results suggest that the diffusion process of Li(I) in the IL dominates the limiting current density in the cell. The highest limiting current density is achieved at a concentration of 0.64 mol dm{sup -3} of LiTFSA. (author)

  14. Development of resistive type superconducting fault current limiter using oxide superconductor; Sankabutsu chodendotai wo mochiita teikogata chodendo genryuki no kaihatsu -muyudo sorenoido koiru no shisaku shiken kekka

    Energy Technology Data Exchange (ETDEWEB)

    Yoneda, E.; Shimada, M.; Nomura, S. [Toshiba Corp., Tokyo (Japan); Okuma, T.; Sato, Y.; Iwata, Y. [Tokyo Electric Power Co., Inc., Tokyo (Japan)

    1999-11-10

    We have advanced the development of resistive superconductivity current limiter using the normal transition of the superconductor until now, and it has produced and tested 6.6kV/1kA single-phase current limiter using the metal system superconductor experimentally. As a result of these evaluations, in turning to the practical application of that the oxide superconductor was used from the metal system superconductor from the viewpoint of wire rod performance, refrigerating machine, insulation performance, it reached the advantageous conclusion. Here, it reports the result that it produced the mischievous prank non-induction coil model experimentally in the mind and tested coil resistance type current-limiting element using the oxide superconductor. (NEDO)

  15. Functional limitations linked to high body mass index, age and current pain in obese women.

    Science.gov (United States)

    Evers Larsson, U; Mattsson, E

    2001-06-01

    To describe functional limitations in obese women. Comparisons of functional limitations in obese women and in a normal-weight reference group regarding mobility, balance and housework transport. A large room with a corridor and staircase nearby. Fifty-seven consecutively selected obese female outpatients, mean age 44 y, body mass index (BMI) 37 kg.m(-2), and 22 voluntary references, mean age 49 y, BMI 22 kg.m(-2). Pain questionnaire (for background data); a new valid and reliable test protocol measuring activities of daily life (ADL), pain and exertion, heart rate, balance and speed. The patients had problems in performing 13 of 16 actions compared with the references (P-values between 0.05 and 0.001). They moved more slowly and had difficulties and /or pain and exertion in flexibility tasks, balancing, activities at floor level (bending and kneeling), climbing stairs and carrying groceries. BMI (P=0.002), age (P=0.02) and current pain (P=0.02) from the lower body predicted functional limitation. The functional test reflected functional limitations in obese women, revealing difficulties and perceived pain in ADL. The test protocol can be used to evaluate the effects of training or dieting. For clinical use we recommend considering BMI, age and current pain for use when individualizing advice on training.

  16. Experimental evaluation of nutrient limitation of phytoplankton communities in the Gulf of Riga

    Science.gov (United States)

    Seppälä, J.; Tamminen, T.; Kaitala, S.

    1999-12-01

    Phytoplankton nutrient limitation was studied in the Gulf of Riga during spring bloom (April 1995), early summer stage (June 1994), cyanobacterial bloom (July 1994) and post cyanobacterial bloom (August 1993). Each year six factorial nutrient enrichment experiments were carried out in various locations in the Gulf; including outer Irbe Strait, northern Gulf and southern Gulf. The responses of natural phytoplankton communities to the nutrient additions (80 μg NH 4-N l -1, 20 μg PO 4-P l -1 and two levels of combined additions) were followed for 3 days using 6 l experimental units. To evaluate the nutrient limitation patterns, time series of chlorophyll a were analysed using polynomial regression models and ranking method, taking advantage of the relatively constant experimental error. Apparent nutrient depletion rates and ratios were estimated, and compared with the changes in particulate nutrient ratios. During the spring diatom bloom in 1995, ambient inorganic nutrient concentrations were still high, and thus phytoplankton biomass did not respond to additions of nutrients. Chlorophyll a specific nutrient depletion rates were low (0.01-0.12 μg N (μg chl a) -1 h -1 and 0.002-0.016 μg P (μg chl a) -1 h -1) and linear over time, thus also revealing that phytoplankton was not limited by these nutrients in that time. In June 1994, there was an areal shift from N limitation in the outer Irbe Strait towards co-limitation in the southern Gulf. Later in July 1994, during the bloom of N-fixing Aphanizomenon flos-aquae, the N limitation was obvious for the whole study area. For this period chlorophyll a specific nutrient depletion rates were high (0.36-0.67 μg N (μg chl a) -1 h -1 and 0.089-0.135 μg P (μg chl a) -1 h -1), and added nutrients were almost totally depleted during the first light period. After the collapse of cyanobacterial bloom in August 1993, the experiment carried out in the southern Gulf indicated P limitation of phytoplankton. The central Gulf was

  17. Operation Tests for SN Transition Superconducting Fault Current Limiter in the Power System Simulator

    Science.gov (United States)

    Kameda, Hideyuki; Torii, Shinji; Kumano, Teruhisa; Sakaki, Hisayoshi; Kubota, Hiroshi; Yasuda, Kenji

    One of important problems to be solved in Japanese trunk transmission systems is the reduction of short circuit capacity. As this countermeasure, double buses are split into two buses in some substations. In recent years, dispersed generators are introduced in lower voltage classes due to the introduction of the electricity deregulation. In such a distribution system as many dispersed generators are introduced, it is a possibility that the fault current becomes beyond the breaking capacity at the occurrence of short circuit. Introduction of superconducting fault current limiters into a power system is very effective as one of the means to solve the above-mentioned problem, and we have studied on the effective introduction method of them and setting method of their parameters. This paper describes the results of the operation tests for SN transition type of a superconducting fault current limiter using 3 phases of FCL modules against various kinds of system faults or inrush current in the Power System Simulator installed at CRIEPI.

  18. Deliberate Microbial Infection Research Reveals Limitations to Current Safety Protections of Healthy Human Subjects.

    Science.gov (United States)

    Evers, David L; Fowler, Carol B; Mason, Jeffrey T; Mimnall, Rebecca K

    2015-08-01

    Here we identify approximately 40,000 healthy human volunteers who were intentionally exposed to infectious pathogens in clinical research studies dating from late World War II to the early 2000s. Microbial challenge experiments continue today under contemporary human subject research requirements. In fact, we estimated 4,000 additional volunteers who were experimentally infected between 2010 and the present day. We examine the risks and benefits of these experiments and present areas for improvement in protections of participants with respect to safety. These are the absence of maximum limits to risk and the potential for institutional review boards to include questionable benefits to subjects and society when weighing the risks and benefits of research protocols. The lack of a duty of medical care by physician-investigators to research subjects is likewise of concern. The transparency of microbial challenge experiments and the safety concerns raised in this work may stimulate further dialogue on the risks to participants of human experimentation.

  19. Enhancing LVRT of DFIG by Using a Superconducting Current Limiter on Rotor Circuit

    Directory of Open Access Journals (Sweden)

    Flávio Oliveira

    2015-12-01

    Full Text Available This paper have studied the dynamic of a 2.0 MW Doubly Fed Induction Generator (DFIG during a severe voltage sag. Using the dynamic model of a DFIG, it was possible to determine the current, Electromagnetic Force and flux behavior during three-phase symmetrical voltage dip. Among the technologies of wind turbines the DFIG is widely employed; however, this machine is extremely susceptible to disturbances from the grid. In order to improve DFIG Low Voltage Ride-Through (LVRT, it is proposed a novel solution, using Superconducting Current Limiter (SCL in two arrangements: one, the SCL is placed between the machine rotor and the rotor side converter (RSC, and another placed in the RSC DC-link. The proposal is validated through simulation using PSCAD™/EMTDC™ and according to requirements of specific regulations. The analysis ensure that both SCL arrangements behave likewise, and are effective in decrement the rotor currents during the disturbance.

  20. Contributions and limitations of experimentation as a method to investigate the educational effects of media

    Directory of Open Access Journals (Sweden)

    Pierre FASTREZ

    2013-07-01

    Full Text Available Communication sciences generally analyse media either as texts, or from the standpoint of their production and reception contexts. Experimental methods are of little use in these cases. Instead, the study of educational communication in a semio-cognitive perspective needs appropriate methods to investigate interactions between the semiotic formats used by the media and their users’ cognitive operations. This article considers the contributions and limitations of the experimental method in this context. We conclude on the necessary articulation of methods in communication sciences, depending on the research questions being examined.

  1. Current transformers with nanocrystalline alloy toroidal core: analytical, computational and experimental studies

    Directory of Open Access Journals (Sweden)

    Benedito Antonio Luciano

    2012-10-01

    Full Text Available In this paper are presented theoretical analysis and experimental results concerning the performance of toroidal cores used in current transformers. For most problems concerning transformers design, analytical methods are useful, but numerical methods provide a better understanding of the transformers electromagnetic behaviour. Numerical field solutions may be used to determine the electrical equivalent circuit parameters of toroidal core current transformers. Since the exciting current of current transformers alters the ratio and phase angle of primary and secondary currents, it is made as small as possible though the use of high permeability and low loss magnetic material in the construction of the core. According to experimental results presented in this work, in comparison with others soft magnetic materials, nanocrystalline alloys appear as the best material to be used in toroidal core for current transformers.

  2. Experimental pain processing in individuals with cognitive impairment: current state of the science

    DEFF Research Database (Denmark)

    Defrin, R; Amanzio, Martina; de Tomasso, M

    2015-01-01

    to cognitively unimpaired individuals. Our current understanding of the neurobiological mechanisms underpinning these alterations is limited, but may be enhanced through the use of animal models of CI which also exhibit alterations in nociceptive responding. Further research employing additional behavioural...

  3. Flux quantum tunneling effect and its influence on the experimental critical current density

    Institute of Scientific and Technical Information of China (English)

    闻海虎; 赵忠贤; GriessenR.

    1995-01-01

    By using magnetic sweeping method, the temperature and magnetic field dependencies of the experimental current density and the normalized relaxation rate have been obtained. The true critical current density corresponding to the zero activation energy has been carried out based on the collective-pinning and the thermally-activated flux motion models, and therefore the influences of the quantum tunneling effect and the thermal activation effect on the experimental critical current density are distinguished. It is found that, with temperature lower than 10 K, the relaxation rate will not drop to zero when T approaches zero K because of the occurrence of the flux quantum tunneling. This additional flux motion further reduces the experimental critical current density j making it saturated with lowering temperature.

  4. Experimental study of yttrium barium copper oxide superconducting tape’s critical current under twisting moment

    Indian Academy of Sciences (India)

    Ziauddin Khan; Ananya Kundu; Subrata Pradhan

    2013-10-01

    Critical current (c) characteristics of 2G YBCO superconducting tape under the influence of twisting moment was experimentally investigated at varying current ramp rates in the self-field. Under a uniform twist, the degradation in the current-carrying capacity of YBCO tape up to 30% was observed at 77 K. The degradation is largely attributed to the shear stress and torsional shear strain resulting from the twisting. The superconductor to resistive transition index, , is also found to behave in an identical manner with increase in the twisting. Finite element analysis (FEA) of the tape in the experimental configuration with twisting moment being applied on to it has been carried out in COMSOL. The torsional strain calculated analytically as per the experimental configuration matches closely with that of FEA results, which shows that the critical current degradation is a function of strain.

  5. Current Treatment of Bacterial Vaginosis—Limitations and Need for Innovation

    Science.gov (United States)

    Bradshaw, Catriona S.; Sobel, Jack D.

    2016-01-01

    Practitioners and patients alike widely recognize the limitations of current therapeutic approaches to the treatment of bacterial vaginosis (BV). Options remain extremely limited, and our inability to prevent the frequently, often relentless symptomatic recurrences of BV and to reduce serious sequelae such as preterm delivery, remains an acknowledged but unresolved shortcoming. Our incomplete understanding of the pathophysiology of this unique form of vaginal dysbiosis has been a significant impediment to developing optimal treatment and prevention approaches. New drugs have not been forthcoming and are not likely to be available in the immediate future; hence, reliance on the optimal use of available agents has become essential as improvised often unproven regimens are implemented. In this review, we will explore the limitations of currently recommended therapies, with a particular focus on the contribution of reinfection and pathogen persistence to BV recurrence, and the development of interventions that target these mechanisms. Ultimately, to achieve sustained cure and effectiveness against BV-associated sequelae, it is possible that we will need approaches that combine antimicrobials with biofilm-disrupting agents and partner treatments in those at risk of reinfection. PMID:27449869

  6. Current Treatment of Bacterial Vaginosis-Limitations and Need for Innovation.

    Science.gov (United States)

    Bradshaw, Catriona S; Sobel, Jack D

    2016-08-15

    Practitioners and patients alike widely recognize the limitations of current therapeutic approaches to the treatment of bacterial vaginosis (BV). Options remain extremely limited, and our inability to prevent the frequently, often relentless symptomatic recurrences of BV and to reduce serious sequelae such as preterm delivery, remains an acknowledged but unresolved shortcoming. Our incomplete understanding of the pathophysiology of this unique form of vaginal dysbiosis has been a significant impediment to developing optimal treatment and prevention approaches. New drugs have not been forthcoming and are not likely to be available in the immediate future; hence, reliance on the optimal use of available agents has become essential as improvised often unproven regimens are implemented. In this review, we will explore the limitations of currently recommended therapies, with a particular focus on the contribution of reinfection and pathogen persistence to BV recurrence, and the development of interventions that target these mechanisms. Ultimately, to achieve sustained cure and effectiveness against BV-associated sequelae, it is possible that we will need approaches that combine antimicrobials with biofilm-disrupting agents and partner treatments in those at risk of reinfection. © The Author 2016. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail journals.permissions@oup.com.

  7. Limitations in Bonding to Dentin and Experimental Strategies to Prevent Bond Degradation

    OpenAIRE

    Liu, Y.; Tjäderhane, L.; Breschi, L; A. Mazzoni; Li, N; J. Mao; Pashley, D.H.; Tay, F.R.

    2011-01-01

    The limited durability of resin-dentin bonds severely compromises the lifetime of tooth-colored restorations. Bond degradation occurs via hydrolysis of suboptimally polymerized hydrophilic resin components and degradation of water-rich, resin-sparse collagen matrices by matrix metalloproteinases (MMPs) and cysteine cathepsins. This review examined data generated over the past three years on five experimental strategies developed by different research groups for extending the longevity of resi...

  8. A Practical Study of the 66kV Fault Current Limiter (FCL) System with Rectifier

    Science.gov (United States)

    Tokuda, Noriaki; Matsubara, Yoshio; Yuguchi, Kyosuke; Ohkuma, Takeshi; Hobara, Natsuro; Takahashi, Yoshihisa

    A fault current limiter (FCL) is extensively expected to suppress fault current, particularly required for trunk power systems heavily connected high-voltage transmission lines, such as 500kV class power system which constitutes the nucleus of the electric power system. By installing such FCL in the power system, the system interconnection is possible without the need to raise the capacity of the circuit breakers, and facilities can be configured for efficiency, among other benefits. For these reasons, fault current limiters based on various principles of operation have been developed both in Japan and abroad. In this paper, we have proposed a new type of FCL system, consisting of solid-state diodes, DC coil and bypass AC coil, and described the specification of distribution power system and 66kV model at the island power system and the superconducting cable power system. Also we have made a practical study of 66kV class, which is the testing items and the future subjects of the rectifier type FCL system.

  9. An experimental comparison of modelling techniques for speaker recognition under limited data condition

    Indian Academy of Sciences (India)

    H S Jayanna; S R Mahadeva Prasanna

    2009-10-01

    Most of the existing modelling techniques for the speaker recognition task make an implicit assumption of sufficient data for speaker modelling and hence may lead to poor modelling under limited data condition. The present work gives an experimental evaluation of the modelling techniques like Crisp Vector Quantization (CVQ), Fuzzy Vector Quantization (FVQ), Self-Organizing Map (SOM), Learning Vector Quantization (LVQ), and Gaussian Mixture Model (GMM) classifiers. An experimental evaluation of the most widely used Gaussian Mixture Model–Universal Background Model (GMM–UBM) is also made. The experimental knowledge is then used to select a subset of classifiers for obtaining the combined classifiers. It is proposed that the combined LVQ and GMM–UBM classifier provides relatively better performance compared to all the individual as well as combined classifiers.

  10. Limiter

    Science.gov (United States)

    Cohen, S.A.; Hosea, J.C.; Timberlake, J.R.

    1984-10-19

    A limiter with a specially contoured front face is provided. The front face of the limiter (the plasma-side face) is flat with a central indentation. In addition, the limiter shape is cylindrically symmetric so that the limiter can be rotated for greater heat distribution. This limiter shape accommodates the various power scrape-off distances lambda p, which depend on the parallel velocity, V/sub parallel/, of the impacting particles.

  11. High-temperature superconducting fault-current limiter - optimisation of superconducting elements

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2004-07-01

    This report summarises the findings of a study initiated to continue the work of a DTI-LINK Collaborative Research Programme 'Enhancing the Properties of Bulk High Temperature Superconductors and their Potential Application as Fault Current Limiters (FCL). Details are given of computer modelling of the quenching process involving the transition from superconducting to normal conducting states undergone by the material when large currents are present. The design of compound elements, and a multi-element model are described along with FCL design covering distribution bus-coupler, embedded generator connection, larger generator connection, hazardous area safety, and interconnection to fault-prone network. The evaluation of thermal loss, test equipment and schedule, the optimised element, installed cost data, and the UK market are considered.

  12. Assessment of the impact of HTSCs on superconducting fault-current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Giese, R.F. [Argonne National Lab., IL (United States); Runde, M. [Energiforsyningens Forskningsinstitutt A/S, Trondheim (Norway)

    1993-03-01

    The possible impact of nitrogen-cooled superconductors on the desip and cost of superconducting fault-current limiters is assessed by considering the technical specifications such devices must meet and by comparing material properties of 77-K and 4-K superconductors. The main advantages of operating superconductors at 77 K are that the refrigeration operating cost is reduced by a factor of up to 25 and the refrigeration capital cost is reduced by a factor of up to 10. The heat capacity is several orders of magnitude Larger at 77 K and at 4 K. This phenomenon increases conductor stability against flux jumps but makes switching from the superconducting to the normal state slow and difficult. Therefore, a high critical current density, probably at least 10{sup 5} A/cm{sup 2}, is required.

  13. A Current Limiting Strategy to Improve Fault Ride-Through of Inverter Interfaced Autonomous Microgrids

    DEFF Research Database (Denmark)

    Sadeghkhani, Iman; Esmail Hamedani Golshan, Mohamad; Guerrero, Josep M.

    2017-01-01

    With high penetration of distributed energy resources (DER), fault management strategy is of great importance for the distribution network operation. The objective of this paper is to propose a current and voltage limiting strategy to enhance fault ride-through (FRT) capability of inverter......-based islanded microgrids (MGs) in which the effects of inverter control system and inverter topology (four/three-wire) are considered. A threephase voltage-sourced inverter (VSI) with multi-loop control system implemented in synchronous, stationary, and natural reference frames is employed in this study...... for both four- and three-wire configurations. The proposed strategy provides high voltage and current quality during overcurrent conditions, which is necessary for sensitive loads. Several time-domain simulation studies are conducted to investigate the FRT capability of the proposed strategy against both...

  14. Design, Test and Demonstration of Saturable Reactor High-Temperature Superconductor Fault Current Limiters

    Energy Technology Data Exchange (ETDEWEB)

    Darmann, Frank [Zenergy Power, Inc., Burlingame, CA (United States); Lombaerde, Robert [Zenergy Power, Inc., Burlingame, CA (United States); Moriconi, Franco [Zenergy Power, Inc., Burlingame, CA (United States); Nelson, Albert [Zenergy Power, Inc., Burlingame, CA (United States)

    2012-03-01

    Zenergy Power has successfully designed, built, tested, and installed in the US electrical grid a saturable reactor Fault Current Limiter. Beginning in 2007, first as SC Power Systems and from 2008 as Zenergy Power, Inc., ZP used DOE matching grant and ARRA funds to help refine the design of the saturated reactor fault current limiter. ZP ultimately perfected the design of the saturated reactor FCL to the point that ZP could reliably design a suitable FCL for most utility applications. Beginning with a very basic FCL design using 1G HTS for a coil housed in a LN2 cryostat for the DC bias magnet, the technology progressed to a commercial system that was offered for sale internationally. Substantial progress was made in two areas. First, the cryogenics cooling system progressed from a sub-cooled liquid nitrogen container housing the HTS coils to cryostats utilizing dry conduction cooling and reaching temperatures down to less than 20 degrees K. Large, round cryostats with warm bore diameters of 1.7 meters enabled the design of large tanks to hold the AC components. Second, the design of the AC part of the FCL was refined from a six legged spider design to a more compact and lighter design with better fault current limiting capability. Further refinement of the flux path and core shape led to an efficient saturated reactor design requiring less Ampere-turns to saturate the core. In conclusion, the development of the saturable reactor FCL led to a more efficient design not requiring HTS magnets and their associated peripheral equipment, which yielded a more economical product in line with the electric utility industry expectations. The original goal for the DOE funding of the ZP project Design, Test and Demonstration of Saturable Reactor High-Temperature Superconductor Fault Current Limiters was to stimulate the HTS wire industry with, first 1G, then 2G, HTS wire applications. Over the approximately 5 years of ZP's product development program, the amount of HTS

  15. Performance of current measurement system in poloidal field power supply for Experimental Advanced Superconducting Tokamak

    Science.gov (United States)

    Liu, D. M.; Li, J.; Wan, B. N.; Lu, Z.; Wang, L. S.; Jiang, L.; Lu, C. H.; Huang, J.

    2016-11-01

    As one of the core subsystems of the Experimental Advanced Superconducting Tokamak (EAST), the poloidal field power system supplies energy to EAST's superconducting coils. To measure the converter current in the poloidal field power system, a current measurement system has been designed. The proposed measurement system is composed of a Rogowski coil and a newly designed integrator. The results of the resistor-inductor-capacitor discharge test and the converter equal current test show that the current measurement system provides good reliability and stability, and the maximum error of the proposed system is less than 1%.

  16. Experimental identification of an azimuthal current in a magnetic nozzle of a radiofrequency plasma thruster

    Science.gov (United States)

    Takahashi, Kazunori; Chiba, Aiki; Komuro, Atsushi; Ando, Akira

    2016-10-01

    The azimuthal plasma current in a magnetic nozzle of a radiofrequency plasma thruster is experimentally identified by measuring the plasma-induced magnetic field. The axial plasma momentum increases over about 20 cm downstream of the thruster exit due to the Lorentz force arising from the azimuthal current. The measured current shows that the azimuthal current is given by the sum of the electron diamagnetic drift and \\mathbf{E}× \\mathbf{B} drift currents, where the latter component decreases with an increase in the magnetic field strength; hence the azimuthal current approaches the electron diamagnetic drift one for the strong magnetic field. The Lorentz force calculated from the measured azimuthal plasma current and the radial magnetic field is smaller than the directly measured force exerted to the magnetic field, which indicates the existence of a non-negligible Lorentz force in the source tube.

  17. Arsenic-induced phosphate limitation under experimental Early Proterozoic oceanic conditions

    Science.gov (United States)

    Chi Fru, Ernest; Hemmingsson, Christoffer; Holm, Mikaela; Chiu, Beverly; Iñiguez, Enrique

    2016-01-01

    Comparison of phosphorus concentrations associated with modern hydrothermal Fe(III)(oxyhydr)oxides and ancient Fe(III) oxide-rich iron formations, is used to estimate bioavailable Precambrian marine phosphorus (P) concentrations. This led to the proposition of a low dissolved P budget of ˜10-25% of present-day levels, before ˜1.9 billion years ago. Estimates incorporating ancient marine Si levels ≥ 0.67 mM instead suggested global dissolved P levels greater than today. Here we unite current experimental models that have considered NaCl solutions containing elevated dissolved Fe(II), Si, Ca2+ and Mg2+ ions in the incorporation of P in Precambrian marine Fe(III)(oxyhydr)oxides, in addition to arsenic as a hydrothermal proxy. We show that the coprecipitation of dissolved P and Fe(III)(oxyhydr)oxides from arsenic-rich marine waters produces an average P distribution coefficient of ˜0.072 (± 0.01) μM-1. This is comparable to the ˜ 0.07 μM-1 predicted for Fe(III)(oxyhydr)oxides in modern arsenic-rich, submarine hydrothermal settings, from which the lower Early Proterozoic dissolved marine P concentrations were predicted. As/P molar ratios below modern seawater ratios removed the negative feedback effect high Si impose on P scavenging by Fe(III)(oxyhydr)oxides. The binding of As(III) to Fe(III)(oxyhydr)oxides exhibits a lower competitive influence on P fixation. As(V) that likely became prominent in the surficially oxidized Early Proterozoic oceans induced dissolved P limitation because of preferential P sequestration at the expense of dissolved As(V) enrichment. The control of As on P scavenging by the precipitating Fe(III)(oxyhydr)oxides is strong regardless of common seawater cations (Mg2+ and Ca2+). The data suggest that the application of Si and Fe(III)(oxyhydr)oxides as an ancient seawater P proxy should consider chemical variability between depositional basins, taking into account the rather strong role hydrothermal arsenic has on the distribution of P in

  18. Performance test of the cryogenic cooling system for the superconducting fault current limiter

    Science.gov (United States)

    Hong, Yong-Ju; In, Sehwan; Yeom, Han-Kil; Kim, Heesun; Kim, Hye-Rim

    2015-12-01

    A Superconducting Fault Current Limiter is an electric power device which limits the fault current immediately in a power grid. The SFCL must be cooled to below the critical temperature of high temperature superconductor modules. In general, they are submerged in sub-cooled liquid nitrogen for their stable thermal characteristics. To cool and maintain the target temperature and pressure of the sub-cooled liquid nitrogen, the cryogenic cooling system should be designed well with a cryocooler and coolant circulation devices. The pressure of the cryostat for the SFCL should be pressurized to suppress the generation of nitrogen bubbles in quench mode of the SFCL. In this study, we tested the performance of the cooling system for the prototype 154 kV SFCL, which consist of a Stirling cryocooler, a subcooling cryostat, a pressure builder and a main cryostat for the SFCL module, to verify the design of the cooling system and the electric performance of the SFCL. The normal operation condition of the main cryostat is 71 K and 500 kPa. This paper presents tests results of the overall cooling system.

  19. Mitigation of commutation failures in LCC-HVDC systems based on superconducting fault current limiters

    Science.gov (United States)

    Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook

    2016-11-01

    Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC-HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC-HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC-HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC-HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.

  20. Mitigation of commutation failures in LCC–HVDC systems based on superconducting fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Lee, Ho-Yun; Lim, Sung-Woo; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2016-11-15

    Commutation failure in line commutated converter based HVDC systems cause severe damages on the entire power grid system. For LCC–HVDC, thyristor valves are turned on by a firing signal but turn off control is governed by the external applied AC voltage from surrounding network. When the fault occurs in AC system, turn-off control of thyristor valves is unavailable due to the voltage collapse of point of common coupling (PCC), which causes the commutation failure in LCC–HVDC link. Due to the commutation failure, the power transfer interruption, dc voltage drop and severe voltage fluctuation in the AC system could be occurred. In a severe situation, it might cause the protection system to block the valves. In this paper, as a solution to prevent the voltage collapse on PCC and to limit the fault current, the application study of resistive superconducting fault current limiter (SFCL) on LCC–HVDC grid system was performed with mathematical and simulation analyses. The simulation model was designed by Matlab/Simulink considering Haenam-Jeju HVDC power grid in Korea which includes conventional AC system and onshore wind farm and resistive SFCL model. From the result, it was observed that the application of SFCL on LCC–HVDC system is an effective solution to mitigate the commutation failure. And then the process to determine optimum quench resistance of SFCL which enables the recovery of commutation failure was deeply investigated.

  1. Water-waves on linear shear currents. A comparison of experimental and numerical results.

    Science.gov (United States)

    Simon, Bruno; Seez, William; Touboul, Julien; Rey, Vincent; Abid, Malek; Kharif, Christian

    2016-04-01

    Propagation of water waves can be described for uniformly sheared current conditions. Indeed, some mathematical simplifications remain applicable in the study of waves whether there is no current or a linearly sheared current. However, the widespread use of mathematical wave theories including shear has rarely been backed by experimental studies of such flows. New experimental and numerical methods were both recently developed to study wave current interactions for constant vorticity. On one hand, the numerical code can simulate, in two dimensions, arbitrary non-linear waves. On the other hand, the experimental methods can be used to generate waves with various shear conditions. Taking advantage of the simplicity of the experimental protocol and versatility of the numerical code, comparisons between experimental and numerical data are discussed and compared with linear theory for validation of the methods. ACKNOWLEDGEMENTS The DGA (Direction Générale de l'Armement, France) is acknowledged for its financial support through the ANR grant N° ANR-13-ASTR-0007.

  2. Study on Recovery Performance of High Tc Superconducting Tapes for Resistive Type Superconducting Fault Current Limiter Applications

    Science.gov (United States)

    kar, Soumen; Kulkarni, Sandeep; Dixit, Manglesh; Singh, Kuwar Pal; Gupta, Alok; Balasubramanyam, P. V.; Sarangi, S. K.; Rao, V. V.

    Recent advances in reliable production of long length high temperature superconducting (HTS) tapes have resulted in commercial application of superconducting fault current limiters (SFCLs) in electrical utility networks. SFCL gives excellent technical performance when compared to conventional fault current limiters. The fast self-recovery from normal state to superconducting state immediately after the fault removal is an essential criterion for resistive type SFCL operation. In this paper, results on AC over-current testing of 1st generation (1G) Bi2223 tapes and 2nd generation (2G) YBCO coated conductors operating at 77 K are reported. From these results, the recovery time is estimated for different available HTS tapes in the market. The current limiting tests have also been performed to study the effective current limitation. Further, the recovery characteristics after the current limitation are quantitatively discussed for repetitive faults for different time intervals in the range of 100 ms to few seconds.

  3. Bringing biofuels on the market. Options to increase EU biofuels volumes beyond the current blending limits

    Energy Technology Data Exchange (ETDEWEB)

    Kampman, B.; Van Grinsven, A.; Croezen, H. [CE Delft, Delft (Netherlands); Verbeek, R.; Van Mensch, P.; Patuleia, A. [TNO, Delft, (Netherlands)

    2013-07-15

    This handbook on biofuels provides a comprehensive overview of different types of biofuels, and the technical options that exist to market the biofuels volumes expected to be consumed in the EU Member States in 2020. The study concludes that by fully utilizing the current blending limits of biodiesel (FAME) in diesel (B7) and bioethanol in petrol (E10) up to 7.9% share of biofuels in the EU transport sector can be technically reached by 2020. Increasing use of advanced biofuels, particularly blending of fungible fuels into diesel (eg. HVO and BTL) and the use of higher ethanol blends in compatible vehicles (e.g. E20), can play an important role. Also, the increased use of biomethane (in particular bio-CNG) and higher blends of biodiesel (FAME) can contribute. However, it is essential for both governments and industry to decide within 1 or 2 years on the way ahead and take necessary actions covering both, the fuels and the vehicles, to ensure their effective and timely implementation. Even though a range of technical options exist, many of these require considerable time and effort to implement and reach their potential. Large scale implementation of the options beyond current blending limits requires new, targeted policy measures, in many cases complemented by new fuel and vehicle standards, adaptation of engines and fuel distribution, etc. Marketing policies for these vehicles, fuels and blends are also likely to become much more important than in the current situation. Each Member State may develop its own strategy tailored to its market and policy objectives, but the EU should play a crucial facilitating role in these developments.

  4. Experimental Measurement of Asymmetric Fluctuations of Poloidal Magnetic Field in Damavand Tokomak at Different Plasma Currents

    Science.gov (United States)

    Moslehi-Fard, Mahmoud; Alinejad, Naser; Rasouli, Chapar; Sadigzadeh, Asghar

    2012-08-01

    Toroidal and Poloidal magnetic fields have an important effect on the tokomak topology. Damavand Tokomak is a small size tokomak characterized with k = 1.2, B t = 1T, R 0 = 36 cm, maximum plasma current is about 35 KA with a discharge time of 21 ms. In this experimental work, the variation of poloidal magnetic field on the torodial cross section is measured and analyzed. In order to measure the polodial magnetic field, 18 probes were installed on the edge of tokomak plasma with ∆θ = 18°, while a limiter was installed inside the torus. Plasma current, I p, induces a polodial magnetic field, B p, smaller than the torodial magnetic field B t. Magnetic lines B produced as a combination of B t and B p, are localized on the nested toroidal magnetic surfaces. The presence of polodial magnetic field is necessary for particles confinement. Mirnov oscillations are the fluctuations of polodial magnetic field, detected by magnetic probes. Disrupted instability in Tokomak typically starts with mirnov oscillations which appear as fluctuations of polodial magnetic field and is detected by magnetic probes. Minor disruptions inside the plasma can contain principal magnetic islands and their satellites can cause the annihilation of plasma confinement. Production of thin layer of turbulent magnetic field lines cause minor disruption. Magnetic limiter may cause the deformation of symmetric equilibrium configuration and chaotic magnetic islands reveal in plasma occurring in thin region of chaotic field lines close to their separatrix. The width of this chaotic layer in the right side of poloidal profile of Damavand Tokomak is smaller than the width in the left side profile because of Shafranov displacement. Ergodic region in the left side of profile develops a perturbation on the magnetic polodial field lines, B p, that are greater in magnitude than that in the right side, although the values of B p on the left side are smaller than that on the right side of the profile. The Left

  5. Progress in American Superconductor's HTS wire and optimization for fault current limiting systems

    Science.gov (United States)

    Malozemoff, Alexis P.

    2016-11-01

    American Superconductor has developed composite coated conductor tape-shaped wires using high temperature superconductor (HTS) on a flexible substrate with laminated metal stabilizer. Such wires enable many applications, each requiring specific optimization. For example, coils for HTS rotating machinery require increased current density J at 25-50 K. A collaboration with Argonne, Brookhaven and Los Alamos National Laboratories and several universities has increased J using an optimized combination of precipitates and ion irradiation defects in the HTS. Major commercial opportunities also exist to enhance electric power grid resiliency by linking substations with distribution-voltage HTS power cables [10]. Such links provide alternative power sources if one substation's transmission-voltage power is compromised. But they must also limit fault currents which would otherwise be increased by such distribution-level links. This can be done in an HTS cable, exploiting the superconductor-to-resistive transition when current exceeds the wires' critical J. A key insight is that such transitions are usually nonuniform; so the wire must be designed to prevent localized hot spots from damaging the wire or even generating gas bubbles in the cable causing dielectric breakdown. Analysis shows that local heating can be minimized by increasing the composite tape's total thickness, decreasing its total resistance in the normal state and decreasing its critical J. This conflicts with other desirable wire characteristics. Optimization of these conflicting requirements is discussed.

  6. Test Results For a 25-m Prototype Fault Current Limiting HTS Cable for Project Hydra

    Energy Technology Data Exchange (ETDEWEB)

    Rey, Christopher M [ORNL; Duckworth, Robert C [ORNL; Demko, Jonathan A [ORNL; Ellis, Alvin R [ORNL; Gouge, Michael J [ORNL; James, David Randy [ORNL; Tuncer, Enis [ORNL

    2010-01-01

    The Oak Ridge National Laboratory (ORNL) has tested a 25-m long prototype High Temperature Superconducting (HTS) cable with inherent Fault-Current Limiting (FCL) capability at its recently upgraded HTS cable test facility in Oak Ridge, TN. The HTS-FCL cable and terminations were designed and fabricated by Ultera, which is a joint venture of Southwire and nkt cables with FCL features and HTS wire provided by American Superconductor Corporation. The overall project is sponsored by the U.S. Department of Homeland Security. The ultimate goal of the 25-m HTS-FCL cable test program was to verify the design and ensure the operational integrity for the eventual installation of a ~ 200-m fully functional HTS-FCL cable in the Consolidated Edison electric grid located in downtown New York City. The 25-m HTS-FCL cable consisted of a three-phase (3- ) Triax design with a cold dielectric between the phases. The HTS-FCL cable had an operational voltage of 13.8 kV phase-to-phase and an operating current of 4000 Arms per phase, which is the highest operating current to date of any HTS cable. The 25-m HTS-FCL cable was subjected to a series of cryogenic and electrical tests. Test results from the 25-m HTS-FCL cable are presented and discussed.

  7. Correlates of experimentation with smoking and current cigarette consumption among adolescents

    Directory of Open Access Journals (Sweden)

    Amanda Gimenes Bonilha

    2014-12-01

    Full Text Available OBJECTIVE: The aim of this study was to analyze social characteristics and stress as correlates of cigarette smoking in adolescence. The main intent was to identify elements that distinguish adolescents who had experimented with smoking and did not progress to regular smoking from those who became current smokers. METHODS: Students at 10 high schools in the city of Ribeirão Preto, Brazil, completed a questionnaire based on an instrument employed in a similar large-scale study. The students were classified as never-smokers or experimenters. The experimenters were subcategorized as having become current smokers or nonprogressors. Analyses were performed using adjusted logistic models. RESULTS: A total of 2,014 students (mean age, 16.2 ± 1.1 years; females, 53% completed the questionnaire. We categorized 1,283 students (63.7% as never-smokers, 244 (12.1% as current smokers, and 487 (24.2% as nonprogressors. We found that experimentation with smoking was associated with being held back a grade in school (OR = 1.80, alcohol intake (low/occasional, OR = 8.92; high/regular, OR = 2.64, illicit drug use (OR = 9.32, having a sibling or cousin who smokes (OR = 1.39, having a friend who smokes (OR = 2.08, and high levels of stress (in females only, OR = 1.32. Factors associated with an increased risk of transitioning from experimenter to current smoker were alcohol intake (low/occasional, OR = 3.28; high/regular, OR = 2.16, illicit drug use (OR = 3.61, and having a friend who smokes (OR = 7.20. CONCLUSIONS: Current smoking was associated with a profile of socioeconomic correlates different from that associated with experimentation only. Our data (showing that current smoking was associated with having a friend who smokes, alcohol intake, and illicit drug use suggest the need for comprehensive approaches to discourage substance use during adolescence.

  8. Calculator for the correction of the experimental specific migration for comparison with the legislative limit

    DEFF Research Database (Denmark)

    Petersen, Jens Højslev; Hoekstra, Eddo J.

    The EURL-NRL-FCM Taskforce on the Fourth Amendment of the Plastic Directive 2002/72/EC developed a calculator for the correction of the test results for comparison with the specific migration limit (SML). The calculator calculates the maximum acceptable specific migration under the given...... experimental conditions in food or food stimulant and indicates whether the test result is in compliance with the legislation. This calculator includes the Fat Reduction Factor, the simulant D Reduction Factor and the factor of the difference in surface-to-volume ratio between test and real food contact....

  9. Current Challenges and Limitations in Antibody-Based Detection of Citrullinated Histones

    Science.gov (United States)

    Neeli, Indira; Radic, Marko

    2016-01-01

    Studies on NETosis demand reliable and convenient markers to monitor the progress of this form of cell death. Because a determining step in the release of nuclear chromatin NETs requires the conversion of arginine residues to citrulline residues in histones by peptidylarginine deiminase, citrullinated histones can provide such a marker. Here, we evaluate antibody reagents for the detection of citrulline residues in histones and observe alarming differences between commercial antisera and mouse and rabbit monoclonal antibodies in their ability to detect their nominal target residues. Differences between antibodies that are currently used to detect citrulline residues in histones could jeopardize efforts to reach a scientific consensus and instead lead to inconsistent and even conflicting conclusions regarding the regulation of histone deimination. Our results will assist others in planning their initial or ongoing studies on peptidylarginine deiminase activity with the use of currently available antibodies. Furthermore, we argue that, along with the careful attention to experimental conditions and calcium concentrations, validated antibody reagents are urgently needed to avoid possible setbacks in the research on NETosis. PMID:27933065

  10. Current Challenges and Limitations in Antibody-Based Detection of Citrullinated Histones

    Directory of Open Access Journals (Sweden)

    Indira Neeli

    2016-11-01

    Full Text Available Studies on NETosis demand reliable and convenient markers to monitor the progress of this form of cell death. Because a determining step in the release of nuclear chromatin NETs requires the conversion of arginine residues to citrulline residues in histones by peptidylarginine deiminase, citrullinated histones can provide such a marker. Here, we evaluate antibody reagents for the detection of citrulline residues in histones and observe alarming differences between commercial antisera and mouse and rabbit monoclonal antibodies in their ability to detect their nominal target residues. Differences between antibodies that are currently used to detect citrulline residues in histones could jeopardize efforts to reach a scientific consensus and instead lead to inconsistent and even conflicting conclusions regarding the regulation of histone deimination. Our results will assist others in planning their initial or ongoing studies on peptidylarginine deiminase activity with the use of currently available antibodies. Further, we argue that, along with the careful attention to experimental conditions and calcium concentrations, validated antibody reagents are urgently needed to avoid possible setbacks in the research on NETosis.

  11. Experiments on current-driven three-dimensional ion sound turbulence. I - Return-current limited electron beam injection. II - Wave dynamics

    Science.gov (United States)

    Stenzel, R. L.

    1978-01-01

    Pulsed electron beam injection into a weakly collisional magnetized background plasma is investigated experimentally; properties of the electron beam and background plasma, as well as the low-frequency instabilities and wave dynamics, are discussed. The current of the injected beam closes via a field-aligned return current of background electrons. Through study of the frequency and wavenumber distribution, together with the electron distribution function, the low-frequency instabilities associated with the pulsed injection are identified as ion acoustic waves driven unstable by the return current. The frequency cut-off of the instabilities predicted from renormalized plasma turbulence theory, has been verified experimentally.

  12. Experimental Results on Current-Driven Turbulence in Plasmas - a Survey

    NARCIS (Netherlands)

    Dekluiver, H.; Perepelkin, N. F.; Hirose, A.

    1991-01-01

    The experimental consequences of plasma turbulence driven by a current parallel to a magnetic field and concurrent anomalous plasma heating are reviewed, with an attempt to deduce universalities in key parameters such as the anomalous electrical conductivities observed in diverse devices. It has

  13. Stem cells for clinical use in cardiovascular medicine: current limitations and future perspectives.

    Science.gov (United States)

    Menasché, Philippe

    2005-10-01

    Cell transplantation is currently gaining a growing interest as a potential new means of improving the prognosis of patients with cardiac failure. The basic assumption is that left ventricular dysfunction is largely due to the loss of a critical number of cardiomyocytes and that it can be partly reversed by implantation of new contractile cells into the postinfarction scars. Primarily for practical reasons, autologous skeletal myoblasts have been the first to undergo clinical trials and now that the feasibility of the procedure is well established, efficacy data are expected from the ongoing randomized studies. Bone marrow stem cells are also generating a great deal of interest, particularly in patients with acute myocardial infarction, and are currently undergoing extensive clinical testing although recent data have raised a cautionary note about the transdifferentiation potential of these cells. While experimental studies and early-phase clinical trials tend to support the concept that cell therapy may enhance cardiac repair, several key issues still need to be addressed including (1) the optimal type of donor cells in relation to the clinical profile of the patients, (2) the mechanism by which cell engraftment improves cardiac function, (3) the optimization of cell survival, (4) the development of less invasive cell delivery techniques and (5) the potential benefits of cell transplantation in nonischemic heart failure. Current evidence suggests, however, that adult stem cells (myogenic or marrow-derived) fail to electromechanically integrate within the recipient heart, thereby mandating the search for second generation cell types able to achieve this goal which is the prerequisite for an effective enhancement of contractile function. Preliminary data suggest that cells that feature a true cardiomyogenic phenotype such as cardiac stem cells and cardiac-precommitted embryonic stem cells may fall in this category and carry the potential for ensuring a true

  14. Development and Testing of a Transmission Voltage SuperLimiter™ Fault Current Limiter

    Energy Technology Data Exchange (ETDEWEB)

    Romanosky, Walter [American Superconductor Corporation, Devens, MA (United States)

    2012-09-01

    This report summarizes work by American Superconductor (AMSC), Los Alamos National Laboratory (LANL), Nexans, Siemens and Southern California Edison on a 138kV resistive type high temperature superconductor (HTS) fault current limiter (FCL) under a cooperative agreement with the U.S. Department of Energy (DOE). Phase 1A encompassed core technology development and system design and was previously reported (see summary that follows in Section 1.1 of the Introduction). This report primarily discusses work performed during Phase 1B, and addresses the fabrication and test of a single-phase prototype FCL. The results are presented along with a discussion of requirements/specifications and lessons learned to aid future development and product commercialization.

  15. Current limit diagrams for dendrite formation in solid-state electrolytes for Li-ion batteries

    Science.gov (United States)

    Raj, R.; Wolfenstine, J.

    2017-03-01

    We build upon the concept that nucleation of lithium dendrites at the lithium anode-solid state electrolyte interface is instigated by the higher resistance of grain boundaries that raises the local electro-chemical potential of lithium, near the lithium-electrode. This excess electro-chemo-mechanical potential, however, is reduced by the mechanical back stress generated when the dendrite is formed within the electrolyte. These parameters are coalesced into an analytical model that prescribes a specific criterion for dendrite formation. The results are presented in the form of current limit diagrams that show the "safe" and "fail" regimes for battery function. A higher conductivity of the electrolyte can reduce dendrite formation.

  16. Growth instability due to lattice-induced topological currents in limited-mobility epitaxial growth models.

    Science.gov (United States)

    Kanjanaput, Wittawat; Limkumnerd, Surachate; Chatraphorn, Patcha

    2010-10-01

    The energetically driven Ehrlich-Schwoebel barrier had been generally accepted as the primary cause of the growth instability in the form of quasiregular moundlike structures observed on the surface of thin film grown via molecular-beam epitaxy (MBE) technique. Recently the second mechanism of mound formation was proposed in terms of a topologically induced flux of particles originating from the line tension of the step edges which form the contour lines around a mound. Through large-scale simulations of MBE growth on a variety of crystalline lattice planes using limited-mobility, solid-on-solid models introduced by Wolf-Villain and Das Sarma-Tamborenea in 2+1 dimensions, we show that there exists a topological uphill particle current with strong dependence on specific lattice crystalline structure. Without any energetically induced barriers, our simulations produce spectacular mounds very similar, in some cases, to what have been observed in many recent MBE experiments. On a lattice where these currents cease to exist, the surface appears to be scale invariant, statistically rough as predicted by the conventional continuum growth equation.

  17. On the increase in the limiting current of an atmospheric-pressure glow discharge in an argon flow

    Science.gov (United States)

    Baldanov, B. B.; Ranzhurov, Ts. V.

    2014-04-01

    The initiation of an atmospheric-pressure glow discharge (APGD) is studied in the multitip cathode-planar anode electrode system through which an argon flow passes. It is shown that sectioning of the cathode and ballast resistances present at corona tips make it possible to substantially expand the current region of the discharge and considerably raise the limiting current of the APGD. The shape of the coronafree electrode is found to influence the limiting discharge current.

  18. Assessment on the influence of resistive superconducting fault current limiter in VSC-HVDC system

    Science.gov (United States)

    Lee, Jong-Geon; Khan, Umer Amir; Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Park, Byung-Bae; Lee, Bang-Wook

    2014-09-01

    Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results.

  19. Assessment on the influence of resistive superconducting fault current limiter in VSC-HVDC system

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Hwang, Jae-Sang; Seong, Jae-Kyu; Shin, Woo-Ju; Park, Byung-Bae; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2014-09-15

    Highlights: • The role of SFCLs in VSC-HVDC systems was evaluated. • Simulation model based on Korea Jeju-Haenam HVDC power system was designed. • An effect and the feasible locations of resistive SFCLs were evaluated. • DC line-to-line, DC line-to-ground and 3 phase AC faults were imposed and analyzed. - Abstract: Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results.

  20. Limit of detection of Toxocara canis larvae in experimentally contaminated bovine milk

    Directory of Open Access Journals (Sweden)

    Edlayne Larissa Gretter Machado Pereira

    2016-02-01

    Full Text Available This study aimed to evaluate the limit of detection of Toxocara canis larvae in experimentally contaminated commercial bovine milk samples, based on a centrifuge-sedimentation technique. Firstly, bovine milk (whole and skim samples were contaminated with 50 T. canis larvae in order to evaluate the interference of milk fat with the recovery of the larvae. Next, the effects of 10% formalin (100 ?L, ether (100 ?L, and a combination of both solutions on the recovery of the larvae was examined. Thereafter, the limit of detection of the larvae was determined using the solution (from step 2 considered optimal for degreasing the milk sample. Samples were contaminated with aliquots of 1, 5, 10, 25, and 50 larvae. For each milk sample (1.0 mL, 15 repetitions were analysed. The recovery of the larvae from the skim milk samples was higher (p = 0.0031 than that from the whole milk samples. No significant difference (p = 0.5681 was observed with regard to the percentage of recovered larvae when comparing the degreasing solutions. Nevertheless, the formalin-ether combination was more efficient for recovering the larvae (73.1% than ether (71.9%, formalin (67.6%, and pure whole milk (70.0%. Concerning the limit of detection (using formalin-ether, all the samples contaminated with 5, 10, 25, and 50 larvae tested positive (minimum: 62.7%. Of the samples contaminated with a single larva, 66.7% tested positive. These results suggest that the centrifugation-sedimentation technique may be useful for recovering larvae of Toxocara spp. in naturally or experimentally contaminated milk samples obtained from a wide range of animal species.

  1. Protein-Protein Interactions: Gene Acronym Redundancies and Current Limitations Precluding Automated Data Integration.

    Science.gov (United States)

    Casado-Vela, Juan; Matthiesen, Rune; Sellés, Susana; Naranjo, José Ramón

    2013-05-31

    Understanding protein interaction networks and their dynamic changes is a major challenge in modern biology. Currently, several experimental and in silico approaches allow the screening of protein interactors in a large-scale manner. Therefore, the bulk of information on protein interactions deposited in databases and peer-reviewed published literature is constantly growing. Multiple databases interfaced from user-friendly web tools recently emerged to facilitate the task of protein interaction data retrieval and data integration. Nevertheless, as we evidence in this report, despite the current efforts towards data integration, the quality of the information on protein interactions retrieved by in silico approaches is frequently incomplete and may even list false interactions. Here we point to some obstacles precluding confident data integration, with special emphasis on protein interactions, which include gene acronym redundancies and protein synonyms. Three human proteins (choline kinase, PPIase and uromodulin) and three different web-based data search engines focused on protein interaction data retrieval (PSICQUIC, DASMI and BIPS) were used to explain the potential occurrence of undesired errors that should be considered by researchers in the field. We demonstrate that, despite the recent initiatives towards data standardization, manual curation of protein interaction networks based on literature searches are still required to remove potential false positives. A three-step workflow consisting of: (i) data retrieval from multiple databases, (ii) peer-reviewed literature searches, and (iii) data curation and integration, is proposed as the best strategy to gather updated information on protein interactions. Finally, this strategy was applied to compile bona fide information on human DREAM protein interactome, which constitutes liable training datasets that can be used to improve computational predictions.

  2. Determining host metabolic limitations on viral replication via integrated modeling and experimental perturbation.

    Directory of Open Access Journals (Sweden)

    Elsa W Birch

    Full Text Available Viral replication relies on host metabolic machinery and precursors to produce large numbers of progeny - often very rapidly. A fundamental example is the infection of Escherichia coli by bacteriophage T7. The resource draw imposed by viral replication represents a significant and complex perturbation to the extensive and interconnected network of host metabolic pathways. To better understand this system, we have integrated a set of structured ordinary differential equations quantifying T7 replication and an E. coli flux balance analysis metabolic model. Further, we present here an integrated simulation algorithm enforcing mutual constraint by the models across the entire duration of phage replication. This method enables quantitative dynamic prediction of virion production given only specification of host nutritional environment, and predictions compare favorably to experimental measurements of phage replication in multiple environments. The level of detail of our computational predictions facilitates exploration of the dynamic changes in host metabolic fluxes that result from viral resource consumption, as well as analysis of the limiting processes dictating maximum viral progeny production. For example, although it is commonly assumed that viral infection dynamics are predominantly limited by the amount of protein synthesis machinery in the host, our results suggest that in many cases metabolic limitation is at least as strict. Taken together, these results emphasize the importance of considering viral infections in the context of host metabolism.

  3. EXPERIMENTAL INVESTIGATIONS ON DIFFUSION CHARACTERISTICS OF HIGH CONCENTRATION JETS IN ENVIRONMENTAL CURRENTS

    Institute of Scientific and Technical Information of China (English)

    张燕; 王道增; 樊靖郁

    2002-01-01

    By means of flow visualization and quantitative measurement, the diffusionpattern and concentration distribution characteristics of high concentration jets verticallydischarged into shallow moving waterbody were experimentally investigated in waterchannel. The interactions between the high concentration jets and environmental flowconditions were analysed, and the formulae of impinging point coordinate and transversespread angle are gained from data analysis. Experimental results indicate that the jets showcomplicated flow patterns and diffusion characteristics in near region, which are differentfrom common submerged jets, and spread downstream in the manner of density currents.

  4. Dual Purpose Simulation: New Data Link Test and Performance Limit Testing of Currently Deployed Data Link

    Science.gov (United States)

    Robinson, Daryl C.

    2002-01-01

    While the results of this paper are similar to those of [I], in this paper technical difficulties present in [I] are eliminated, producing better results, enabling one to more readily see the benefits of Prioritized CSMA (PCSMA). A new analysis section also helps to generalize this research so that it is not limited to exploration of the new concept of PCSMA. Commercially available network simulation software, OPNET version 7.0, simulations are presented involving an important application of the Aeronautical Telecommunications Network (ATN), Controller Pilot Data Link Communications (CPDLC) over the Very High Frequency Data Link Mode 2 (VDL-2). Communication is modeled for essentially all incoming and outgoing nonstop air-traffic for just three United States cities: Cleveland, Cincinnati, and Detroit. The simulation involves 111 Air Traffic Control (ATC) ground stations, 32 airports distributed throughout the U.S., which are either sources or destinations for the air traffic landing or departing from the three cities, and also 1,235 equally equipped aircraft-taking off, flying realistic free-flight trajectories, and landing in a 24-hr period. Collision-less PCSMA is successfully tested and compared with the traditional CSMA typically associated with VDL-2. The performance measures include latency, throughput, and packet loss. As expected, PCSMA is much quicker and more efficient than traditional CSMA. These simulation results show the potency of PCSMA for implementing low latency, high throughput and efficient connectivity. Moreover, since PCSMA outperforms traditional CSMA, by simulating with it, we can determine the limits of performance beyond which traditional CSMA may not pass. So we have the tools to determine the traffic-loading conditions where traditional CSMA will fail, and we are testing a new and better data link that could replace it with relative ease. Work is currently being done to drastically expand the number of flights to make the simulation more

  5. Experimental Investigation of a Direct Methanol Fuel Cell with Hilbert Fractal Current Collectors

    Directory of Open Access Journals (Sweden)

    Jing-Yi Chang

    2014-01-01

    Full Text Available The Hilbert curve is a continuous type of fractal space-filling curve. This fractal curve visits every point in a square grid with a size of 2×2, 4×4, or any other power of two. This paper presents Hilbert fractal curve application to direct methanol fuel cell (DMFC current collectors. The current collectors are carved following first, second, and third order Hilbert fractal curves. These curves give the current collectors different free open ratios and opening perimeters. We conducted an experimental investigation into DMFC performance as a function of the free open ratio and opening perimeter on the bipolar plates. Nyquist plots of the bipolar plates are made and compared using electrochemical impedance spectroscopy (EIS experiments to understand the phenomena in depth. The results obtained in this paper could be a good reference for future current collector design.

  6. Experimental Research of Harmonic Spectrum of Currents at Traction Drive with PMSM

    Directory of Open Access Journals (Sweden)

    J. Novak

    2011-06-01

    Full Text Available The paper deals with the significant results of the experimental research of current harmonic spectrum of traction drive with permanent magnet synchronous motor. The experiments were done on a special workplace with a real traction drive for wheel vehicles. Current harmonic spectrum was analyzed by a specialized device on the base of central measuring station. The knowledge of current marked subharmonic components of stator winding is the most significant finding of experiments. The frequencies of these components are given by multiples of frequency of mechanical speeds. The subharmonic components also pass to input DC current of drive. This fact is important in particular from the point of view of legislative requirements to electromagnetic compatibility of drive with railway interlocking devices.

  7. Evaluating the osseointegration of nanostructured titanium implants in animal models: Current experimental methods and perspectives (Review).

    Science.gov (United States)

    Babuska, Vaclav; Moztarzadeh, Omid; Kubikova, Tereza; Moztarzadeh, Amin; Hrusak, Daniel; Tonar, Zbynek

    2016-09-15

    The aim of this paper is to review the experimental methods currently being used to evaluate the osseointegration of nanostructured titanium implants using animal models. The material modifications are linked to the biocompatibility of various types of oral implants, such as laser-treated, acid-etched, plasma-coated, and sand-blasted surface modifications. The types of implants are reviewed according to their implantation site (endoosseous, subperiosteal, and transosseous implants). The animal species and target bones used in experimental implantology are carefully compared in terms of the ratio of compact to spongy bone. The surgical technique in animal experiments is briefly described, and all phases of the histological evaluation of osseointegration are described in detail, including harvesting tissue samples, processing undemineralized ground sections, and qualitative and quantitative histological assessment of the bone-implant interface. The results of histological staining methods used in implantology are illustrated and compared. A standardized and reproducible technique for stereological quantification of bone-implant contact is proposed and demonstrated. In conclusion, histological evaluation of the experimental osseointegration of dental implants requires careful selection of the experimental animals, bones, and implantation sites. It is also advisable to use larger animal models and older animals with a slower growth rate rather than small or growing experimental animals. Bones with a similar ratio of compact to spongy bone, such as the human maxilla and mandible, are preferred. A number of practical recommendations for the experimental procedures, harvesting of samples, tissue processing, and quantitative histological evaluations are provided.

  8. Experimental manifestation of the breakpoint region in the current-voltage characteristics of intrinsic Josephson junctions

    Science.gov (United States)

    Irie, A.; Shukrinov, Yu. M.; Oya, G.

    2008-10-01

    The experimental evidence of the breakpoint on the current-voltage characteristics (IVCs) of the stacks of intrinsic Josephson junctions (IJJs) is presented. The influence of the capacitive coupling on the IVCs of Bi2Sr2CaCu2Oy IJJs has been investigated. At 4.2K, clear breakpoint region is observed on the branches in the IVCs. It is found that due to the coupling between junctions, the hysteresis observed on the IVC is small compared to that expected from the McCumber parameter. Measurements agree well with the results predicted by the capacitively coupled Josephson junction model including the diffusion current.

  9. New Experimental Limit on the Electric Dipole Moment of the Electron in a Paramagnetic Insulator

    CERN Document Server

    Kim, Y J; Lamoreaux, S K; Visser, G; Kunkler, B; Matlashov, A V; Kunkler, B

    2011-01-01

    We report results of an experimental search for the intrinsic Electric Dipole Moment (EDM) of the electron using a solid-state technique. The experiment employs a paramagnetic, insulating gadolinium gallium garnet (GGG) that has a large magnetic response at low temperatures. The presence of the eEDM would lead to a small but non-zero magnetization as the GGG sample is subject to a strong electric field. We search for the resulting Stark-induced magnetization with a sensitive magnetometer. Recent progress on the suppression of several sources of background allows the experiment to run free of spurious signals at the level of the statistical uncertainties. We report our first limit on the eEDM of $(-5.57 \\pm 7.98 \\pm 0.12)\\times10^{-25}$e$\\cdot$cm with 5 days of data averaging.

  10. Experimental limit on the ratio of the gravitational mass to the inertial mass of antihydrogen

    Science.gov (United States)

    Fajans, Joel; Wurtele, Jonathan; Charman, Andrew; Zhmoginov, Andrey

    2012-10-01

    Physicists have long wondered if the gravitational interactions between matter and antimatter might be different from those between matter and itself. While there are many indirect indications that no such differences exist, i.e., that the weak equivalence principle holds, there have been no direct, free-fall style, experimental tests of gravity on antimatter. By searching for a propensity for antihydrogen atoms to fall downward when released from the ALPHA antihydrogen trap, we have determined that we can reject ratios of the gravitational mass to the inertial mass of antihydrogen greater than about 100 at a statistical significance level of 5%. A similar search places somewhat lower limits on a negative gravitational mass, i.e., on antigravity.

  11. Experimental demonstration of radiation flux measurement accuracy surpassing the Nyquist limit

    CERN Document Server

    Lieu, Richard; Kibble, T W B; Johann,; Shi, C -H

    2016-01-01

    In this paper we present an extensive and detailed experimental assessment of the performance of homodyne detection vs direct detection for determining the flux of an incoherent light source. The intensity of a laser reference signal is measured, before and after contamination by photon bunching noise (transimpedance gain of 20k), simultaneously. Moreover, the measurement containing photon bunching noise was done using two schemes: direct and homodyne detection, also with no appreciable time delay. The sampling rate of all measurements is the same, and is always higher than the frequency limit of the bunching noise. By carefully comparing the resulting three time series, it is found, surprisingly, that the homodyne detection of the incoherent signal resembles more closely the variance and variability pattern of the original coherent signal, and the effect is most prominent at the highest sampling frequency. It therefore appears flux estimates made using the shot noise of the field were able to overcome the Ny...

  12. Current Limitations in the Control and Spread of Ticks that Affect Livestock: A Review

    Directory of Open Access Journals (Sweden)

    Agustín Estrada-Peña

    2013-04-01

    Full Text Available Ticks are well-known parasites that affect livestock productivity. This paper reviews the current knowledge regarding the spread of ticks with their impact in animal health and the limitations to achieve effective control measures. The forecasted trends in climate play an obvious role in promoting the spread of ticks in several regions. It appears that climate warming is pivotal in the spread and colonization of new territories by Rhipicephalus microplus in several regions of Africa. The reported increase in altitude of this tick species in the mountainous regions of Central and South America appears to be driven by such general trends in climate change. This factor, however, is not the only single contributor to the spread of ticks. The poor management of farms, uncontrolled movements of domestic animals, abundance of wild animals, and absence of an adequate framework to capture the ecological plasticity of certain ticks may explain the complexity of the control measures. In this paper, we review several details regarding the relationships of ticks with the environment, wild fauna and competition with other species of ticks. Our intention is to highlight these relationships with the aim to produce a coherent framework to explore tick ecology and its relationship with animal production systems.

  13. Clinical Uses of Botulinum Neurotoxins: Current Indications, Limitations and Future Developments

    Directory of Open Access Journals (Sweden)

    Sheng Chen

    2012-10-01

    Full Text Available Botulinum neurotoxins (BoNTs cause flaccid paralysis by interfering with vesicle fusion and neurotransmitter release in the neuronal cells. BoNTs are the most widely used therapeutic proteins. BoNT/A was approved by the U.S. FDA to treat strabismus, blepharospam, and hemificial spasm as early as 1989 and then for treatment of cervical dystonia, glabellar facial lines, axillary hyperhidrosis, chronic migraine and for cosmetic use. Due to its high efficacy, longevity of action and satisfactory safety profile, it has been used empirically in a variety of ophthalmological, gastrointestinal, urological, orthopedic, dermatological, secretory, and painful disorders. Currently available BoNT therapies are limited to neuronal indications with the requirement of periodic injections resulting in immune-resistance for some indications. Recent understanding of the structure-function relationship of BoNTs prompted the engineering of novel BoNTs to extend therapeutic interventions in non-neuronal systems and to overcome the immune-resistance issue. Much research still needs to be done to improve and extend the medical uses of BoNTs.

  14. Possibilities and limitations of current technologies for quantification of biological extracellular vesicles and synthetic mimics

    Science.gov (United States)

    Maas, Sybren L.N.; de Vrij, Jeroen; van der Vlist, Els J.; Geragousian, Biaina; van Bloois, Louis; Mastrobattista, Enrico; Schiffelers, Raymond M.; Wauben, Marca H.M.; Broekman, Marike L.D.; Nolte-'t Hoen, Esther N.M.

    2015-01-01

    Nano-sized extracelullar vesicles (EVs) released by various cell types play important roles in a plethora of (patho)physiological processes and are increasingly recognized as biomarkers for disease. In addition, engineered EV and EV-inspired liposomes hold great potential as drug delivery systems. Major technologies developed for high-throughput analysis of individual EV include nanoparticle tracking analysis (NTA), tunable resistive pulse sensing (tRPS) and high-resolution flow cytometry (hFC). Currently, there is a need for comparative studies on the available technologies to improve standardization of vesicle analysis in diagnostic or therapeutic settings. We investigated the possibilities, limitations and comparability of NTA, tRPS and hFC for analysis of tumor cell-derived EVs and synthetic mimics (i.e. differently sized liposomes). NTA and tRPS instrument settings were identified that significantly affected the quantification of these particles. Furthermore, we detailed the differences in absolute quantification of EVs and liposomes using the three technologies. This study increases our understanding of possibilities and pitfalls of NTA, tRPS and hFC, which will benefit standardized and large-scale clinical application of (engineered) EVs and EV-mimics in the future. PMID:25555362

  15. Combining Pharmacological and Psychological Treatments for Binge Eating Disorder: Current Status, Limitations, and Future Directions.

    Science.gov (United States)

    Grilo, Carlos M; Reas, Deborah L; Mitchell, James E

    2016-06-01

    Binge eating disorder (BED) is characterized by recurrent binge eating and marked distress about binge eating without the extreme compensatory behaviors for weight control that characterize other eating disorders. BED is prevalent, associated strongly with obesity, and is associated with heightened levels of psychological, psychiatric, and medical concerns. This article provides an overview of randomized controlled treatments for combined psychological and pharmacological treatment of BED to inform current clinical practice and future treatment research. In contrast to the prevalence and significance of BED, to date, limited research has been performed on combining psychological and pharmacological treatments for BED to enhance outcomes. Our review here found that combining certain medications with cognitive behavioral therapy (CBT) or behavioral weight loss (BWL) interventions produces superior outcomes to pharmacotherapy only but does not substantially improve outcomes achieved with CBT/BWL only. One medication (orlistat) has improved weight losses with CBT/BWL albeit minimally, and only one medication (topiramate) has enhanced reductions achieved with CBT in both binge eating and weight. Implications for future research are discussed.

  16. Development, Testing and Installation of a Superconducting Fault Current Limiter for Medium Voltage Distribution Networks

    Science.gov (United States)

    Martini, Luciano; Bocchi, Marco; Ascade, Massimo; Valzasina, Angelo; Rossi, Valerio; Angeli, Giuliano; Ravetta, Cesare

    Since 2009 Ricerca sul Sistema Energetico (RSE S.p.A.) has been involved in the design of resistive-type Superconducting Fault Current Limiter (SFCL) for MV applications to be installed in the A2A Reti Elettriche S.p.A distribution grid in the Milano area. The project started with simulations, design and testing activities for a singlephase device; in this paper we report on the successive step, which is concerned with developing, testing and installation at the hosting utility of the final three-phase SFCL prototype. The result of this research activity is a resistive-type 9 kV/3.4 MVA SFCL device, based on first generation (1G) BSCCO tapes, developed by RSE in the framework of a R&D national project. Owing to the positive test results of partial discharge, dielectric and shortcircuit results the three-phase SFCL device is being to be installed in the A2A distribution grid in the Milano area and it is going to be soon energized starting a one-year long field-testing activity.

  17. An experimental apparatus for diffraction-limites soft x-ray nanofocusing

    Energy Technology Data Exchange (ETDEWEB)

    Merthe, Daniel; Goldberg, Kenneth; Yashchuk, Valeriy; Yuan, Sheng; McKinney, Wayne; Celestre, Richard; Mochi, Iacopo; Macdougall, James; Morrison, Gregory; Rakawa, Senajith; Anderson, Erik; Smith, Brian; Domning, Edward; Warwick, Tony; Padmore, Howard

    2011-10-21

    Realizing the experimental potential of high-brightness, next generation synchrotron and free-electron laser light sources requires the development of reflecting x-ray optics capable of wavefront preservation and high-resolution nano-focusing. At the Advanced Light Source (ALS) beamline 5.3.1, we are developing broadly applicable, high-accuracy, in situ, at-wavelength wavefront measurement techniques to surpass 100-nrad slope measurement accuracy for diffraction-limited Kirkpatrick-Baez (KB) mirrors. The at-wavelength methodology we are developing relies on a series of wavefront-sensing tests with increasing accuracy and sensitivity, including scanning-slit Hartmann tests, grating-based lateral shearing interferometry, and quantitative knife-edge testing. We describe the original experimental techniques and alignment methodology that have enabled us to optimally set a bendable KB mirror to achieve a focused, FWHM spot size of 150 nm, with 1 nm (1.24 keV) photons at 3.7 mrad numerical aperture. The predictions of wavefront measurement are confirmed by the knife-edge testing.The side-profiled elliptically bent mirror used in these one-dimensional focusing experiments was originally designed for a much different glancing angle and conjugate distances. This work demonstrates that high-accuracy, at-wavelength wavefront-slope feedback can be used to optimize the pitch, roll, and mirror-bending forces in situ, using procedures that are deterministic and repeatable.

  18. High performance predictive current control of a three phase VSI: An experimental assessment

    Indian Academy of Sciences (India)

    Vikas Kumar; Prerna Gaur; A P Mittal

    2014-12-01

    Delay has a significant role to play in the implementation of the predictive current control scheme as large amount of calculations are involved. Compensating delay in the predictive current controller design can lead to an improved load current total harmonic distortion (THD) and also an increased switching frequency. Minimization of switching frequency while maintaining the lower value of load current THD requires multiple objective optimization which is achieved by optimizing a single objective function, constructed using weighting factors as a linear combination of individual objective function. The effect of weighting factor on the switching frequency minimization and the current tracking error with delay compensation for the two level voltage source inverter (VSI) are investigated in this paper. The outcomes of the predictive current control using an optimized weighting factor which is calculated using branch and bound algorithm with the delay compensation are compared with the PWM based current control scheme. The experimental tests are conducted on a 2.2 kW VSI to verify the simulation observations.

  19. CO2 diffusion into pore spaces limits weathering rate of an experimental basalt landscape

    Science.gov (United States)

    van Haren, Joost; Dontsova, Katerina; Barron-Gafford, Greg A.; Troch, Peter A.; Chorover, Jon; DeLong, Stephen B.; Breshears, David D.; Huxman, Travis E.; Pelletier, Jon D.; Saleska, Scott; Zeng, Xubin; Ruiz, Joaquin

    2017-01-01

    Basalt weathering is a key control over the global carbon cycle, though in situ measurements of carbon cycling are lacking. In an experimental, vegetation-free hillslope containing 330 m3 of ground basalt scoria, we measured real-time inorganic carbon dynamics within the porous media and seepage flow. The hillslope carbon flux (0.6–5.1 mg C m–2 h–1) matched weathering rates of natural basalt landscapes (0.4–8.8 mg C m–2 h–1) despite lacking the expected field-based impediments to weathering. After rainfall, a decrease in CO2 concentration ([CO2]) in pore spaces into solution suggested rapid carbon sequestration but slow reactant supply. Persistent low soil [CO2] implied that diffusion limited CO2 supply, while when sufficiently dry, reaction product concentrations limited further weathering. Strong influence of diffusion could cause spatial heterogeneity of weathering even in natural settings, implying that modeling studies need to include variable soil [CO2] to improve carbon cycling estimates associated with potential carbon sequestration methods.

  20. Computational and experimental studies of laser cutting of the current collectors for lithium-ion batteries

    Science.gov (United States)

    Lee, Dongkyoung; Patwa, Rahul; Herfurth, Hans; Mazumder, Jyotirmoy

    2012-07-01

    Sizing electrodes is an important step during Lithium-ion battery manufacturing processes since poor cut edge affects battery performance significantly and sometime leads to fire hazard. Mechanical cutting could result in a poor cut quality with defects. The cutting quality can be improved by using a laser, due to its high energy concentration, fast processing time, small heat-affected zone, and high precision. The cutting quality is highly influenced by operating parameters such as laser power and scanning speed. Thus, we studied a numerical simulation to provide a guideline for achieving clear edge quality. In order to simulate electrodes laser cutting for Lithium-Ion batteries, understanding the behavior of current collectors is crucial. This study focuses on current collectors, such as pure copper and aluminium. Numerical studies utilized a 3D self-consistent mathematical model for laser-material interaction. Observations of penetration time, depth, and threshold during laser cutting processes of current collectors are described. The model is validated experimentally by cutting current collectors and single side-coated electrodes with a single mode fiber laser. The copper laser cutting is laser intensity and interaction time dependent process. The aluminium laser cutting depends more on laser intensity than the interaction time. Numerical and experimental results show good agreement.

  1. Design, Fabrication and Testing of a Superconducting Fault Current Limiter (SFCL)

    Energy Technology Data Exchange (ETDEWEB)

    Gouge, M..; Schwenterly, S.W.; Hazelton, D. (SuperPower, Inc.)

    2011-06-15

    The purpose of this project was to conduct R&D on specified components and provide technical design support to a SuperPower team developing a high temperature superconducting Fault Current Limiter (SFCL). ORNL teamed with SuperPower, Inc. on a Superconductivity Partnerships with Industry (SPI) proposal for the SFCL that was submitted to DOE and approved in FY 2003. A contract between DOE and SuperPower, Inc. was signed on July 14, 2003 to design, fabricate and test the SFCL. This device employs high temperature superconducting (HTS) elements and SuperPower's proprietary technology. The program goal was to demonstrate a device that will address a broad range of the utility applications and meet utility industry requirements. This DOE-sponsored Superconductivity Partnership with Industry project would positively impact electric power transmission reliability and security by introducing a new element in the grid that can significantly mitigate fault currents and provide lower cost solutions for grid protection. The project will conduct R&D on specified components and provide technical design support to a SuperPower-led team developing a SFCL as detailed in tasks 1-5 below. Note the SuperPower scope over the broad SPI project is much larger than that shown below which indicates only the SuperPower tasks that are complementary to the ORNL tasks. SuperPower is the Project Manager for the SFCL program, and is responsible for completion of the project on schedule and budget. The scope of work for ORNL is to provide R&D support for the SFCL in the following four broad areas: (1) Assist with high voltage subsystem R&D, design, fabrication and testing including characterization of the general dielectric performance of LN2 and component materials; (2) Consult on cryogenic subsystem R&D, design, fabrication and testing; (3) Participate in project conceptual and detailed design reviews; and (4) Guide commercialization by participation on the Technical Advisory Board (TAB

  2. Principle and experimental investigation of current-driven negative-inductance superconducting quantum interference device

    Science.gov (United States)

    Li, Hao; Liu, Jianshe; Zhang, Yingshan; Cai, Han; Li, Gang; Liu, Qichun; Han, Siyuan; Chen, Wei

    2017-03-01

    A negative-inductance superconducting quantum interference device (nSQUID) is an adiabatic superconducting logic device with high energy efficiency, and therefore a promising building block for large-scale low-power superconducting computing. However, the principle of the nSQUID is not that straightforward and an nSQUID driven by voltage is vulnerable to common mode noise. We investigate a single nSQUID driven by current instead of voltage, and clarify the principle of the adiabatic transition of the current-driven nSQUID between different states. The basic logic operations of the current-driven nSQUID with proper parameters are simulated by WRspice. The corresponding circuit is fabricated with a 100 A cm‑2 Nb-based lift-off process, and the experimental results at low temperature confirm the basic logic operations as a gated buffer.

  3. Investigation on the Arc Ignition Characteristics and Energy Absorption of Liquid Metal Current Limiter Based on Self-Pinch Effect

    Institute of Scientific and Technical Information of China (English)

    JU Xingbao; SUN Haishun; YANG Zhuo; ZHANG Junmin

    2016-01-01

    The GaInSn liquid metal current limiter based on the fluid pinch effect has broad application prospects due to its particular properties.However,the limited rated current and ability of power dissipation are the critical problems for its wide application.Firstly,the temperature distribution of the liquid metal current limiter (LMCL) was obtained by experiments with a rated current of 1 kA and the arc ignition phenomenon was observed with 1.5 kA,which indicates that the rated current is mainly limited by the arc rather than the high temperature compared to the traditional switchgears.Furthermore,an improved method is proposed by adding the paralleled pure resistance,impedance or another LMCL element to protect the setup from the fault energy concentration in the setup.The problem of a slower arc voltage increasing rate can be solved by adding a paralleled impedance with suitable parameters.Finally,the current limiting properties based on the improved method were investigated and the alternating oscillating current was found between two paralleled LMCL elements owing to their deviation of arc ignition in reality.

  4. Experimental study of the velocity of density currents in convergent and divergent channels

    Institute of Scientific and Technical Information of China (English)

    Hasan Torabi POUDEH; Samad EMAMGHOLIZADEH; Manoocher Fathi-MOGHADAM

    2014-01-01

    The head velocity of the density current in the convergent and divergent channel is a key parameter for evaluating the extent to which suspended material travels, and for determining the type and distribution of sediment in the water body. This study experimentally evaluated the effects of the reach degree of convergence and divergence on the head velocity of the density current. Experiments were conducted in the flume with 6.0 m long, 0.72 m width and 0.6 m height. The head velocity was measured at three convergent degrees (-8o;-12o;-26o), at three divergent degrees (8o; 12o; 26o) and two slopes (0.009, 0.016) for various discharges. The measured head velocity of the density current is compared with the head velocity of the density current in the constant cross section channel. Based on non-dimensional and statistical analysis, relations as linear multiple regression are offered for predicting head velocity of the density current in the convergent, divergent and constant cross section channel. Also the results of this research show that for the same slope and discharge, the head velocity of the density current in the convergent and divergent channel are greater and less than the head velocity of the constant cross section, respectively.

  5. Scanning fast and slow: current limitations of 3 Tesla functional MRI and future potential

    Directory of Open Access Journals (Sweden)

    Roland N Boubela

    2014-02-01

    Full Text Available Functional MRI at 3T has become a workhorse for the neurosciences, e.g., neurology, psychology, and psychiatry, enabling non-invasive investigation of brain function and connectivity. However, BOLD-based fMRI is a rather indirect measure of brain function, confounded by fluctuation related signals, e.g. head or brain motion, brain pulsation, blood flow, intermixed with susceptibility differences close or distant to the region of neuronal activity. Even though a plethora of preprocessing strategies have been published to address these confounds, their efficiency is still under discussion. In particular, physiological signal fluctuations closely related to brain supply may mask BOLD signal changes related to true neuronal activation. Here we explore recent technical and methodological advancements aimed at disentangling the various components, employing fast multiband vs. standard EPI, in combination with fast temporal ICA.Our preliminary results indicate that fast (TR< 0.5s scanning may help to identify and eliminate physiologic components, increasing tSNR and functional contrast. In addition, biological variability can be studied and task performance better correlated to other measures. This should increase specificity and reliability in fMRI studies. Furthermore, physiological signal changes during scanning may then be recognized as a source of information rather than a nuisance. As we are currently still undersampling the complexity of the brain, even at a rather coarse macroscopic level, we should be very cautious in the interpretation of neuroscientific findings, in particular when comparing different groups (e.g., age, sex, medication, pathology, etc.. From a technical point of view our goal should be to sample brain activity at layer specific resolution with low TR, covering as much of the brain as possible without violating SAR limits. We hope to stimulate discussion towards a better understanding and a more quantitative use of fMRI.

  6. Experimental Verification of Overlimiting Current by Surface Conduction and Electro-osmotic Flow in Microchannels

    CERN Document Server

    Nam, Sungmin; Heo, Joonseong; Lim, Geunbae; Bazant, Martin Z; Sung, Gunyong; Kim, Sung Jae

    2014-01-01

    Possible mechanisms of overlimiting current in unsupported electrolytes, exceeding diffusion limitation, have been intensely studied for their fundamental significance and applications to desalination, separations, sensing, and energy storage. In bulk membrane systems, the primary physical mechanism is electro-convection, driven by electro-osmotic instability on the membrane surface. It has recently been predicted that confinement by charged surfaces in microchannels or porous media favors two new mechanisms, electro-osmotic flow (EOF) and surface conduction (SC), driven by large electric fields in the depleted region acting on the electric double layers on the sidewalls. Here, we provide the first direct evidence for the transition from SC to EOF above a critical channel height, using in situ particle tracking and current-voltage measurements in a micro/nanofluidic device. The dependence of the over-limiting conductance on channel depth (d) is consistent with theoretical predictions, scaling as d^-1 for SC a...

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2007-07-01

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

  8. Fault Ride Though Control of Photovoltaic Grid-connected Inverter with Current-limited Capability under Offshore Unbalanced Voltage Conditions

    DEFF Research Database (Denmark)

    Liu, Wenzhao; Guo, Xiaoqiang; Savaghebi, Mehdi;

    2016-01-01

    of the excessive current phenomenon with the conventional fault ride through control is discussed. The quantitative analysis of the current peak value is conducted and a new current-limiting control strategy is proposed to achieve the flexible power control and successful fault ride through in a safe current......The photovoltaic (PV) inverter installed on board experiences the excessive current stress in case of the offshore unbalanced voltage fault ride through (FRT), which significantly affects the operation reliability of the power supply system. In order to solve the problem, the inherent mechanism...

  9. Flexible Power Regulation and Current-limited Control of Grid-connected Inverter under Unbalanced Grid Voltage Faults

    DEFF Research Database (Denmark)

    Guo, Xiaoqiang; Liu, Wenzhao; Lu, Zhigang

    2017-01-01

    The grid-connected inverters may experience excessive current stress in case of unbalanced grid voltage Fault Ride Through (FRT), which significantly affects the reliability of the power supply system. In order to solve the problem, the inherent mechanisms of the excessive current phenomenon...... with the conventional FRT solutions are discussed. The quantitative analysis of three phase current peak values are conducted and a novel current-limited control strategy is proposed to achieve the flexible active and reactive power regulation and successful FRT in a safe current operation area with the aim...

  10. Influence of current limitation on voltage stability with voltage sourced converter HVDC

    DEFF Research Database (Denmark)

    Zeni, Lorenzo; Jóhannsson, Hjörtur; Hansen, Anca Daniela;

    2013-01-01

    A first study of voltage stability with relevant amount of Voltage Sourced Converter based High Voltage Direct Current (VSC-HVDC) transmission is presented, with particular focus on the converters’ behaviour when reaching their rated current. The detrimental effect of entering the current...

  11. Proceedings of the 1979 workshop on beam current limitations in storage rings, July 16-27, 1979

    Energy Technology Data Exchange (ETDEWEB)

    Pellegrini, C. (ed.)

    1979-01-01

    The Workshop on Beam Current Limitations in Storage Rings was held at Brookhaven National Laboratory from July 16 to 27, 1979. The purpose of this Workshop was to discuss the physical mechanisms limiting the beam current or current density in accelerators or storage rings. Many of these machines are now being built or planned for a variety of applications, such as colliding beam experiments, synchrotron light production, heavy ion beams. This diversity was reflected in the Workshop and in the papers which have been contributed to these Proceedings. The twenty-one papers from the workshop were incorporated individually in the data base. (GHT)

  12. Characterization of superconducting coil for fault current limitation; Caracterizacao de bobina supercondutora para limitacao de corrente de curto-circuito

    Energy Technology Data Exchange (ETDEWEB)

    Polasek, Alexander; Dias, Rodrigo; Niedu, Daniel Brito; Ogasawara, Tsuneharu; Oliveira Filho, Orsino Borges de; Serra, Eduardo Torres [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil); Gomes Junior, George; Amorim, Helio Salim [Coordenacao dos Programas de Pos-Graduacao em Engeharia (COPPE/UFRJ), Rio de Janeiro, RJ (Brazil)

    2010-07-01

    The increasing power demand has been raising fault currents up to dangerous levels. Superconducting fault current limiters are a promising solution for this problem. In the present work, we studied a superconducting Bi-2212 coil that is used for fault current limitation. Samples were analyzed by XRD, SEM/EDS and measurement of critical temperature (Tc). The Rietveld method was employed for phase quantification. Relatively high Bi-2212 fractions were found. However, Tc varies from a sample to another one. Variations of local Tc are attributed to variations of oxygen content in Bi- 2212 phase. (author)

  13. Experimental study of depth-limited open-channel flows over a gravel bed

    Institute of Scientific and Technical Information of China (English)

    Cheng Zeng; Chiwai Li; Hongwu Tang; Lingling Wang; Jingqiao Mao

    2015-01-01

    abstract Laboratory experiments of depth-limited open-channel flows over a gravel bed were conducted in the study. Two gravel patches with identical individual element size and different lengths (3.81 m and 7.5 m) were tested. The depth-limited uniform flow regime with relative submergence Sr ( ¼ D/ks) ranging from 2.68 to 5.94 was produced by adjusting the tailgate weir. The velocity profiles were measured by using both an ultra-sound velocity profiler (UVP) and an acoustic Doppler velocimeter (ADV). The conventional methods used to determine the zero-plane displacement and estimate the bed shear velocity were then reviewed and compared. The measured double-averaged (DA) velocity profiles were found to fit well with the log law and defect law with a non-universal Karman constantκ.κ-value remains nearly constant and in the range from 0.2 to 0.3 for the long patch (LP) cases andκ-values are scattered within a wider range from 0.3 to 0.5 for the short patch (SP) cases. While the Br-value in log law remains constant and equal to 8.5 for LP cases, the Br-value was found to decrease with the increase of the dimensionless roughness height ksþ for SP cases. The streamwise turbulence intensity distributions were found to be independent on the patch length and agree well with the available experimental data in the intermediate region and wall region. The Manning resistance coefficient and Darcy–Weisbach friction factor were analyzed. Theκ-value decreases to 0.22 for the fitting of the logarithmic flow resistance law under small relative submergence. The value of the integration constant Ar in the logarithmic law falls within the normal range between 3.25 and 6.25.

  14. EXPERIMENTAL STUDY ON BED-LOAD SEDIMENT TRANSPORT IN IRREGULAR WAVE-CURRENT COEXISTENT FIELD

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    In order to evaluate bed-load sediment transport in an irregular wave-current coexistent field, a series of experiments were completed in laboratory with an irregularly oscillating tray, which was specially designed to simulate the irregular wave-current coexistent field. Experimental results are presented on the initial motion of sediment and the rates of transport over flat horizontal bed. Testing conditions included three interaction angles, 0°, 45°, 90° and six kinds of grain sizes. Four kinds (0.2mm, 0.46mm, 0.85mm and 1.3mm) were used for the tests of initial motion, while the other two kinds (0.38mm and 1.1mm) for the tests of transport rate. Comparisons between experimental results of initial motion and modified Shields curve indicate that the Shields curve is still valid for the case of irregular wave-current coexistent field. Analysis of flow regime shows that initial conditions fall within smooth-turbulent transitional region. The results of transport rate show us that net sediment transport rate can be expressed approximately as the function of the maximum bottom shear stress and mean shear stress. A dimensionless formula is proposed on the basis of mechanism "Waves erode sediments, tides transport sediments".

  15. Numerical simulation and experimental validation of a direct current air corona discharge under atmospheric pressure

    Institute of Scientific and Technical Information of China (English)

    Liu Xing-Hua; He Wei; Yang Fan; Wang Hong-Yu; Liao Rui-Jin; Xiao Han-Guang

    2012-01-01

    Air corona discharge is one of the critical problems associated with high-voltage equipment.Investigating the corona mechanism plays a key role in enhancing the electrical insulation performance.An improved self-consistent multi-component two-dimensional plasma hybrid model is presented for the simulation of a direct current atmospheric pressure corona discharge in air.The model is based on plasma hydrodynamic and chemical models,and includes 12 species and 26 reactions.In addition,the photoionization effect is introduced into the model.The simulation on a bar-plate electrode configuration with an inter-electrode gap of 5.0 mm is carried out.The discharge voltage-current characteristics and the current density distribution predicted by the hybrid model agree with the experimental measurements.In addition,the dynamics of volume charged species generation,discharge current waveform,current density distribution at an electrode,charge density,electron temperature,and electric field variations are investigated in detail based on the model.The results indicate that the model can contribute valuable insights into the physics of an air plasma discharge.

  16. They see a rat, we seek a cure for diseases: the current status of animal experimentation in medical practice.

    Science.gov (United States)

    Kehinde, Elijah O

    2013-01-01

    The objective of this review article was to examine current and prospective developments in the scientific use of laboratory animals, and to find out whether or not there are still valid scientific benefits of and justification for animal experimentation. The PubMed and Web of Science databases were searched using the following key words: animal models, basic research, pharmaceutical research, toxicity testing, experimental surgery, surgical simulation, ethics, animal welfare, benign, malignant diseases. Important relevant reviews, original articles and references from 1970 to 2012 were reviewed for data on the use of experimental animals in the study of diseases. The use of laboratory animals in scientific research continues to generate intense public debate. Their use can be justified today in the following areas of research: basic scientific research, use of animals as models for human diseases, pharmaceutical research and development, toxicity testing and teaching of new surgical techniques. This is because there are inherent limitations in the use of alternatives such as in vitro studies, human clinical trials or computer simulation. However, there are problems of transferability of results obtained from animal research to humans. Efforts are on-going to find suitable alternatives to animal experimentation like cell and tissue culture and computer simulation. For the foreseeable future, it would appear that to enable scientists to have a more precise understanding of human disease, including its diagnosis, prognosis and therapeutic intervention, there will still be enough grounds to advocate animal experimentation. However, efforts must continue to minimize or eliminate the need for animal testing in scientific research as soon as possible. © 2013 S. Karger AG, Basel.

  17. Experimental manifestation of the breakpoint region in the current-voltage characteristics of intrinsic Josephson junctions

    OpenAIRE

    Irie, A.; Shukrinov, Yu M.; Oya, G.

    2008-01-01

    The experimental evidence of the breakpoint on the current-voltage characteristics (IVCs) of the stacks of intrinsic Josephson junctions (IJJs) is presented. The influence of the capacitive coupling on the IVCs of Bi$_2$Sr$_2$CaCu$_2$O$_y$ IJJs has been investigated. At 4.2 K, clear breakpoint region is observed on the branches in the IVCs. It is found that the hysteresis observed on the IVC is suppressed due to the coupling compared with that expected from the McCumber parameter. Measurement...

  18. 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.

  19. Operating characteristics of superconducting fault current limiter using 24kV vacuum interrupter driven by electromagnetic repulsion switch

    Energy Technology Data Exchange (ETDEWEB)

    Endo, M; Hori, T; Koyama, K; Kaiho, K; Yanabu, S [Tokyo Denki University, 2-2 Kandanishiki-chou Chiyoda-ku Tokyo 101-8457 (Japan); Yamaguchi, I; Arai, K [National Institute of Advanced Industrial Science and Technology(AIST), 1-1-1 Umezono, Tsukuba-shi, Ibaraki 305-8565 (Japan)], E-mail: yanabu@e.dendai.ac.jp

    2008-02-01

    Using a high temperature superconductor, we constructed and tested a model Superconducting Fault Current Limiter (SFCL). SFCL which has a vacuum interrupter with electromagnetic repulsion mechanism. We set out to construct high voltage class SFCL. We produced the electromagnetic repulsion switch equipped with a 24kV vacuum interrupter(VI). There are problems that opening speed becomes late. Because the larger vacuum interrupter the heavier weight of its contact. For this reason, the current which flows in a superconductor may be unable to be interrupted within a half cycles of current. In order to solve this problem, it is necessary to change the design of the coil connected in parallel and to strengthen the electromagnetic repulsion force at the time of opening the vacuum interrupter. Then, the design of the coil was changed, and in order to examine whether the problem is solvable, the current limiting test was conducted. We examined current limiting test using 4 series and 2 parallel-connected YBCO thin films. We used 12-centimeter-long YBCO thin film. The parallel resistance (0.1{omega}) is connected with each YBCO thin film. As a result, we succeed in interrupting the current of superconductor within a half cycle of it. Furthermore, series and parallel-connected YBCO thin film could limit without failure.

  20. Experimental Investigations on PV Powered SVM-DTC Induction Motor without AC Phase Current Sensors

    Directory of Open Access Journals (Sweden)

    T. Muthamizhan

    2014-05-01

    Full Text Available The paper presents a low-cost, phase-current reconstruction algorithm for space vector modulated direct torque controlled induction motor using the information obtained from only one shunt resistor which is in series with low side switches in a conventional three-phase inverter. The aim is to develop a low-cost high - performance induction motor drive. It uses the dc-link voltage and dc current to reconstruct the stator currents needed to estimate the motor flux and the electromagnetic torque. Photovoltaic arrays convert solar power to dc electric power; uses chopper and dc-ac inverter to fed three phase Induction Motor. The chopper used here is current fed full bridge boost dc-dc converter, which is preferred and extensively used in high voltage applications and advantageous over voltage fed converters. The inverter switches are controlled by PWM techniques obtained from SVM-DTC of IM. The experimental investigations are given to prove the ability of the proposed scheme of reproducing the performances of a SVM- DTC IM drive.

  1. Experimental and theoretical investigations on the singularity of the intensity factor of the current in high temperature superconductors

    Science.gov (United States)

    Zhang, Xingyi; Huang, Yi; Zhou, Jun; Zhou, Youhe

    2013-08-01

    This paper presents experimental and analytical investigations into the distribution of current around a through-edge crack located in an infinitely long cylindrical high temperature superconductor (HTS) on the basis of the Bean model. Current distributions around the crack in the HTS without deformation are obtained by a simple conformal mapping. It is shown that the current is singular at the tip of the crack. An intensity factor of the current is introduced to characterize the singularity, the order of which is equal to -1. Additionally, an experimental verification according to the trapped field distributions around the crack is carried out, and the experimental results show little difference with the theoretical analysis.

  2. Recent experimental results of effects of perfluoroalkyl substances in laboratory animals - Relation to current regulations and guidance values.

    Science.gov (United States)

    Lilienthal, Hellmuth; Dieter, Hermann H; Hölzer, Jürgen; Wilhelm, Michael

    2017-03-02

    The detection of perfluoroalkyl substances (PFAS) in surface and drinking water from various countries raised the attention to the presence of these chemicals in environmental probes and led to several regulatory actions to limit exposure in human beings. There was particular concern about perfluorooctanoic acid (PFOA) and perfluorooctane sulfonate (PFOS), due to their former wide-spread use. Recently, several institutions published revisions of former regulatory or recommended maximum concentrations in drinking water and food, which are markedly lower than the former values. The present short overview describes the current regulations for PFAS and compares them with the outcome of several experimental studies in laboratory animals at low-level exposure to PFOA and PFOS. In addition, regulations for short-chain PFAS are presented which, due to lack of toxicological information, are evaluated according to the concepts of Threshold of Toxicological Concern (TTC) or the Health-related Indication Values (HRIV).

  3. Experimental Determination of DT Yield in High Current DD Dense Plasma Focii

    Energy Technology Data Exchange (ETDEWEB)

    Lowe, D. R. [National Security Technologies, LLC; Hagen, E. C. [National Security Technologies, LLC; Meehan, B. T. [National Security Technologies, LLC; Springs, R. K. [University of Nevada, Las Vegas; O' Brien, R. J. [University of Nevada, Las Vegas

    2013-06-18

    Dense Plasma Focii (DPF), which utilize deuterium gas to produce 2.45 MeV neutrons, may in fact also produce DT fusion neutrons at 14.1 MeV due to the triton production in the DD reaction. If beam-target fusion is the primary producer of fusion neutrons in DPFs, it is possible that ejected tritons from the first pinch will interact with the second pinch, and so forth. The 2 MJ DPF at National Security Technologies’ Losee Road Facility is able to, and has produced, over 1E12 DD neutrons per pulse, allowing an accurate measurement of the DT/DD ratio. The DT/DD ratio was experimentally verified by using the (n,2n) reaction in a large piece of praseodymium metal, which has a threshold reaction of 8 MeV, and is widely used as a DT yield measurement system1. The DT/DD ratio was experimentally determined for over 100 shots, and then compared to independent variables such as tube pressure, number of pinches per shot, total current, pinch current and charge voltage.

  4. Experimental demonstration of a new radiation mechanism: emission by an oscillating, accelerated, superluminal polarization current

    CERN Document Server

    Ardavan, A; Ardavan, H; Fopma, J; Halliday, D; Hayes, W

    2004-01-01

    We describe the experimental implementation of a superluminal ({\\it i.e.} faster than light {\\it in vacuo}) polarization current distribution that both oscillates and undergoes centripetal acceleration. Theoretical treatments lead one to expect that the radiation emitted from each volume element of such a polarization current will comprise a \\v{C}erenkov-like envelope with two sheets that meet along a cusp. The emission from the experimental machine is in good agreement with these expectations, the combined effect of the volume elements leading to tightly-defined beams of a well-defined geometry, determined by the source speed and trajectory. In addition, over a restricted range of angles, we detect the presence of cusps in the emitted radiation. These are due to the detection over a short time period (in the laboratory frame) of radiation emitted over a considerably longer period of source time. Consequently, the intensity of the radiation at these angles was observed to decline more slowly with increasing d...

  5. 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.

  6. Experimental and numerical examination of eddy (Foucault) currents in rotating micro-coils: Generation of heat and its impact on sample temperature.

    Science.gov (United States)

    Aguiar, Pedro M; Jacquinot, Jacques-François; Sakellariou, Dimitris

    2009-09-01

    The application of nuclear magnetic resonance (NMR) to systems of limited quantity has stimulated the use of micro-coils (diameter Foucault (eddy) currents, which generate heat. We report the first data acquired with a 4mm MACS system and spinning up to 10kHz. The need to spin faster necessitates improved methods to control heating. We propose an approximate solution to calculate the power losses (heat) from the eddy currents for a solenoidal coil, in order to provide insight into the functional dependencies of Foucault currents. Experimental tests of the dependencies reveal conditions which result in reduced sample heating and negligible temperature distributions over the sample volume.

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

    Directory of Open Access Journals (Sweden)

    F. Gharedaghi

    2011-11-01

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

  8. Experimentally Manipulating Items Informs on the (Limited) Construct and Criterion Validity of the Humor Styles Questionnaire.

    Science.gov (United States)

    Ruch, Willibald; Heintz, Sonja

    2017-01-01

    How strongly does humor (i.e., the construct-relevant content) in the Humor Styles Questionnaire (HSQ; Martin et al., 2003) determine the responses to this measure (i.e., construct validity)? Also, how much does humor influence the relationships of the four HSQ scales, namely affiliative, self-enhancing, aggressive, and self-defeating, with personality traits and subjective well-being (i.e., criterion validity)? The present paper answers these two questions by experimentally manipulating the 32 items of the HSQ to only (or mostly) contain humor (i.e., construct-relevant content) or to substitute the humor content with non-humorous alternatives (i.e., only assessing construct-irrelevant context). Study 1 (N = 187) showed that the HSQ affiliative scale was mainly determined by humor, self-enhancing and aggressive were determined by both humor and non-humorous context, and self-defeating was primarily determined by the context. This suggests that humor is not the primary source of the variance in three of the HQS scales, thereby limiting their construct validity. Study 2 (N = 261) showed that the relationships of the HSQ scales to the Big Five personality traits and subjective well-being (positive affect, negative affect, and life satisfaction) were consistently reduced (personality) or vanished (subjective well-being) when the non-humorous contexts in the HSQ items were controlled for. For the HSQ self-defeating scale, the pattern of relationships to personality was also altered, supporting an positive rather than a negative view of the humor in this humor style. The present findings thus call for a reevaluation of the role that humor plays in the HSQ (construct validity) and in the relationships to personality and well-being (criterion validity).

  9. Current Limiting Performance of Three-Phase Concentric Transformer Type SFCL at Unbalanced Fault Conditions

    OpenAIRE

    Shirai, Yasuyuki; Noda, Syo; Yamabe, Kenta; Hattori, Keisuke; Baba, Jumpei; Nishihara, Taichi; Nitta, Tanzo; Kobayashi, Shinichi; Sato, Kenichi

    2013-01-01

    We have proposed a transformer type SFCL whose primary and secondary superconducting coils have rewound structure. The primary coil is connected to a power line. The secondary one is short-circuited and has fewer turns than the primary coil. For small fault current, only the secondary coil turns to normal state. Inductive component of impedance at the primary terminal mainly appears. For larger fault current, the primary coil also turns to normal state, resistive component additively appears....

  10. Status and Progress of a Fault Current Limiting Hts Cable to BE Installed in the con EDISON Grid

    Science.gov (United States)

    Maguire, J.; Folts, D.; Yuan, J.; Henderson, N.; Lindsay, D.; Knoll, D.; Rey, C.; Duckworth, R.; Gouge, M.; Wolff, Z.; Kurtz, S.

    2010-04-01

    In the last decade, significant advances in the performance of second generation (2G) high temperature superconducting wire have made it suitable for commercially viable applications such as electric power cables and fault current limiters. Currently, the U.S. Department of Homeland Security is co-funding the design, development and demonstration of an inherently fault current limiting HTS cable under the Hydra project with American Superconductor and Consolidated Edison. The cable will be approximately 300 m long and is being designed to carry 96 MVA at a distribution level voltage of 13.8 kV. The underground cable will be installed and energized in New York City. The project is led by American Superconductor teamed with Con Edison, Ultera (Southwire and nkt cables joint venture), and Air Liquide. This paper describes the general goals, design criteria, status and progress of the project. Fault current limiting has already been demonstrated in 3 m prototype cables, and test results on a 25 m three-phase cable will be presented. An overview of the concept of a fault current limiting cable and the system advantages of this unique type of cable will be described.

  11. A Versatile Control Scheme For Dynamic Voltage Restorer To Limit Downstream Fault Currents

    Directory of Open Access Journals (Sweden)

    A.Nagendra

    2014-12-01

    Full Text Available The Dynamic Voltage Restorer (DVR is a custom power device utilized to counteract voltage sags. It injects controlled three-phase ac voltages in series with the supply voltage, subsequent to voltage sag, to enhance voltage quality by adjusting the voltage magnitude, wave shape, and phase angle. The DVR is conventionally bypassed during a downstream fault to prevent potential adverse impacts on the fault and to protect the DVR components against the fault current. This paper proposes an augmented control strategy for the DVR that provides:1 voltage-sag compensation under balanced and unbalanced conditions and 2 a fault current interruption (FCI function. This paper introduces and evaluates an auxiliary control strategy for downstream fault current interruption in a radial distribution line by means of a dynamic voltage restorer (DVR. The proposed controller supplements the voltage-sag compensation control of the DVR. It does not require phaselocked loop and independently controls the magnitude and phase angle of the injected voltage for each phase. Fast least error squares digital filters are used to estimate the magnitude and phase of the measured voltages and effectively reduce the impacts of noise, harmonics, and disturbances on the estimated phasor parameters, and this enables effective fault current interrupting even under arcing fault conditions. The performance of the DVR for fault current interruption is analyzed by using MATLAB/SIMULINK software.

  12. Clinical and experimental studies on polyherbal formulations for diabetes:current status and future prospective

    Institute of Scientific and Technical Information of China (English)

    Ahmad Ghorbani

    2014-01-01

    Diabetes is a leading cause of morbidity and mortality in the world. There is currently an active search for antidiabetic drugs with greater effectiveness with fewer and less adverse side effects. Although numerous individual herbs have been experimentally or clinically reported to possess antidiabetic effects, considerably less research has been conducted on polyherbal compounds. It is believed that herbal compounds containing multiple plant products have synergistic antidiabetic effects and could enhance the desired actions. Several polyherbal formulations have been studied as therapeutic agents in diabetes management. To describe the current state of research on polyherbal compounds in the treatment of diabetes, an extensive review of literature was undertaken on several major databases. This paper presents what is known about the efifcacy of these polyherbal formulations and compare their antidiabetic effects with those of current oral hypoglycemic drugs as reference. The percent decrease in blood glucose, lipids and other biochemical parameters achieved by each product in diabetic animals and patients is reported. Also, the possible mechanisms responsible for hypoglycemic action of polyherbal formulations are discussed.

  13. A numerical study on the feasibility evaluation of a hybrid type superconducting fault current limiter applying thyristors

    Energy Technology Data Exchange (ETDEWEB)

    Nam, Seok Ho; Lee, Woo Seung; Lee, Ji Ho; Hwang, Young Jin; Ko, Tae Kuk [Yonsei University, Seoul (Korea, Republic of)

    2013-12-15

    Smart fault current controller (SFCC) proposed in our previous work consists of a power converter, a high temperature superconducting (HTS) DC reactor, thyristors, and a control unit [1]. SFCC can limit and control the current by adjusting firing angles of thyristors when a fault occurs. SFCC has complex structure because the HTS DC reactor generates the loss under AC. To use the DC reactor under AC, rectifier that consists of four thyristors is needed and it increases internal resistance of SFCC. For this reason, authors propose a hybrid type superconducting fault current limiter (SFCL). The hybrid type SFCL proposed in this paper consists of a non-inductive superconducting coil and two thyristors. To verify the feasibility of the proposed hybrid type SFCL, simulations about the interaction of the superconducting coil and thyristors are conducted when fault current flows in the superconducting coil. Authors expect that the hybrid type SFCL can control the magnitude of the fault current by adjusting the firing angles of thyristors after the superconducting coil limits the fault current at first peak.

  14. Estimation of the spatial distribution of traps using space-charge-limited current measurements in an organic single crystal

    KAUST Repository

    Dacuña, Javier

    2012-09-06

    We used a mobility edge transport model and solved the drift-diffusion equation to characterize the space-charge-limited current of a rubrene single-crystal hole-only diode. The current-voltage characteristics suggest that current is injection-limited at high voltage when holes are injected from the bottom contact (reverse bias). In contrast, the low-voltage regime shows that the current is higher when holes are injected from the bottom contact as compared to hole injection from the top contact (forward bias), which does not exhibit injection-limited current in the measured voltage range. This behavior is attributed to an asymmetric distribution of trap states in the semiconductor, specifically, a distribution of traps located near the top contact. Accounting for a localized trap distribution near the contact allows us to reproduce the temperature-dependent current-voltage characteristics in forward and reverse bias simultaneously, i.e., with a single set of model parameters. We estimated that the local trap distribution contains 1.19×1011 cm -2 states and decays as exp(-x/32.3nm) away from the semiconductor-contact interface. The local trap distribution near one contact mainly affects injection from the same contact, hence breaking the symmetry in the charge transport. The model also provides information of the band mobility, energy barrier at the contacts, and bulk trap distribution with their corresponding confidence intervals. © 2012 American Physical Society.

  15. High or low-side solid state relay with current limiting and operational testing

    Science.gov (United States)

    Dolland, C. R.

    1984-07-01

    The switch comprises a circuit from a first output terminal via parallel MOS devices in series with current-sensing resistance to a second output terminal, with alternative high-side and low-side configurations having a load between the second terminal and ground, or the first terminal and the DC supply voltage. An input terminal for a digital control signal is coupled via an input diode and two Schmitt Trigger CMOS inverters to a control lead for the gates of the switch. A current overload or short circuit protection circuit coupled between the current-sensor and the input diode comprises two transistors coupled by a diode. A built-in test circuit for indicating the switch condition (on, off, shorted or open) comprises MOS transistors having their gates connected to voltage dividers at the two output terminals, and their drains connected to discrete indication terminals.

  16. Thickness scaling of the space-charge-limited current in poly(p-phenylene vinylene)

    NARCIS (Netherlands)

    Blom, PWM; Tanase, C; de Leeuw, DM; Coehoorn, R

    2005-01-01

    Charge transport in light-emitting diodes (LEDs) based on a polyp-phenylene vinylene) (PPV) derivative is investigated as a function of sample thickness. Via the thickness dependence, the contributions from the electric field and charge carrier density to the mobility in space-charge-limited (SCL) d

  17. Active to sterile neutrino mixing limits from neutral-current interactions in MINOS

    CERN Document Server

    Adamson, P; Ayres, D S; Backhouse, C; Barr, G; Bishai, M; Blake, A; Bock, G J; Boehnlein, D J; Bogert, D; Cavanaugh, S; Cherdack, D; Childress, S; Coelho, J A B; Coleman, S J; Corwin, L; Cronin-Hennessy, D; Danko, I Z; de Jong, J K; Devenish, N E; Diwan, M V; Dorman, M; Escobar, C O; Evans, J J; Falk, E; Feldman, G J; Frohne, M V; Gallagher, H R; Gomes, R A; Goodman, M C; Gouffon, P; Graf, N; Gran, R; Grant, N; Grzelak, K; Habig, A; Harris, D; Hartnell, J; Hatcher, R; Himmel, A; Holin, A; Huang, X; Hylen, J; Ilic, J; Irwin, G M; Isvan, Z; Jaffe, D E; James, C; Jensen, D; Kafka, T; Kasahara, S M S; Koizumi, G; Kopp, S; Kordosky, M; Kreymer, A; Lang, K; Lefeuvre, G; Ling, J; Litchfield, P J; Loiacono, L; Lucas, P; Mann, W A; Marshak, M L; Mayer, N; McGowan, A M; Mehdiyev, R; Meier, J R; Messier, M D; Miller, W H; Mishra, S R; Mitchell, J; Moore, C D; Morfín, J; Mualem, L; Mufson, S; Musser, J; Naples, D; Nelson, J K; Newman, H B; Nichol, R J; Nicholls, T C; Nowak, J A; Oliver, W P; Orchanian, M; Paley, J; Patterson, R B; Pawloski, G; Pearce, G F; Petyt, D A; Phan-Budd, S; Pittam, R; Plunkett, R K; Qiu, X; Ratchford, J; Raufer, T M; Rebel, B; Rodrigues, P A; Rosenfeld, C; Sanchez, H A Rubin M C; Schneps, J; Schreiner, P; Sharma, R; Shanahan, P; Sousa, A; Stamoulis, P; Strait, M; Tagg, N; Talaga, R L; Tetteh-Lartey, E; Thomas, J; Thomson, M A; Tinti, G; Toner, R; Torretta, D; Tzanakos, G; Urheim, J; Vahle, P; Viren, B; Walding, J J; Weber, A; Webb, R C; White, C; Whitehead, L; Wojcicki, S G; Zwaska, R

    2011-01-01

    Results are reported from a search for active to sterile neutrino oscillations in the MINOS long-baseline experiment, based on the observation of neutral-current neutrino interactions, from an exposure to the NuMI neutrino beam of $7.07\\times10^{20}$ protons on target. A total of 802 neutral-current event candidates is observed in the Far Detector, compared to an expected number of $754\\pm28\\rm{(stat.)}\\pm{37}\\rm{(syst.)}$ for oscillations among three active flavors. The fraction $f_s$ of disappearing \

  18. Current strategies for improving access and adherence to antiretroviral therapies in resource-limited settings

    Directory of Open Access Journals (Sweden)

    Scanlon ML

    2013-01-01

    Full Text Available Michael L Scanlon,1,2 Rachel C Vreeman1,21Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN, USA; 2USAID, Academic Model Providing Access to Healthcare (AMPATH Partnership, Eldoret, KenyaAbstract: The rollout of antiretroviral therapy (ART significantly reduced human immunodeficiency virus (HIV-related morbidity and mortality, but good clinical outcomes depend on access and adherence to treatment. In resource-limited settings, where over 90% of the world’s HIV-infected population resides, data on barriers to treatment are emerging that contribute to low rates of uptake in HIV testing, linkage to and retention in HIV care systems, and suboptimal adherence rates to therapy. A review of the literature reveals limited evidence to inform strategies to improve access and adherence with the majority of studies from sub-Saharan Africa. Data from observational studies and randomized controlled trials support home-based, mobile and antenatal care HIV testing, task-shifting from doctor-based to nurse-based and lower level provider care, and adherence support through education, counseling and mobile phone messaging services. Strategies with more limited evidence include targeted HIV testing for couples and family members of ART patients, decentralization of HIV care, including through home- and community-based ART programs, and adherence promotion through peer health workers, treatment supporters, and directly observed therapy. There is little evidence for improving access and adherence among vulnerable groups such as women, children and adolescents, and other high-risk populations and for addressing major barriers. Overall, studies are few in number and suffer from methodological issues. Recommendations for further research include health information technology, social-level factors like HIV stigma, and new research directions in cost-effectiveness, operations, and implementation. Findings from this review make a

  19. An Experimental Investigation of Passive Variable-Pitch Vertical-Axis Ocean Current Turbine

    Directory of Open Access Journals (Sweden)

    Ridho Hantoro

    2011-04-01

    Full Text Available Vertical-axis hydrokinetic turbines with fixed pitch blades typically suffer from poor starting torque, low efficiency and shaking due to large fluctuations in both radial and tangential force with azimuth angle. Maximizing the turbine power output can be achieved only if the mechanism of generation of the hydrodynamic force on the blades is clearly identified and tools to design high-performance rotors are developed. This paper describes an initial experimental investigation to understand more of the performance on vertical-axis turbine related to the effect of fixed-pitch and passive variable-pitch application using airfoil NACA 0018. Comparative analysis according to aspects of rotation and tip speed ratios was discussed. Information regarding the changes of foil position in passive variable-pitch during rotation at a limited range of flow velocity variations test was obtained and analyzed.

  20. Rapid Detection Strategies for the Global Threat of Zika Virus: Current State, New Hypotheses and Limitations

    Directory of Open Access Journals (Sweden)

    Shruti Shukla

    2016-10-01

    Full Text Available The current scenario regarding the widespread Zika virus (ZIKV has resulted in numerous diagnostic studies, specifically in South America and in locations where there is frequent entry of travelers returning from ZIKV-affected areas, including pregnant women with or without clinical symptoms of ZIKV infection. The World Health Organization, WHO, announced that millions of cases of ZIKV are likely to occur in the United States of America in the near future. This situation has created an alarming public health emergency of international concern requiring the detection of this life-threatening viral candidate due to increased cases of newborn microcephaly associated with ZIKV infection. Hence, this review reports possible methods and strategies for the fast and reliable detection of ZIKV with particular emphasis on current updates, knowledge and new hypotheses that might be helpful for medical professionals in poor and developing countries that urgently need to address this problem. In particular, we emphasize liposome-based biosensors. Although these biosensors are currently among the less popular tools for human disease detection, they have become useful tools for the screening and detection of pathogenic bacteria, fungi and viruses because of their versatile advantageous features compared to other sensing devices. This review summarizes the currently available methods employed for the rapid detection of ZIKV and suggests an innovative approach involving the application of a liposome-based hypothesis for the development of new strategies for ZIKV detection and their use as effective biomedicinal tools.

  1. Space-charge-limited current and the effect of light in CdS-single crystals

    NARCIS (Netherlands)

    Driedonks, F.; Zijlstra, R.J.J.

    1966-01-01

    Thin CdS-single crystals in darkness show current-voltage characteristics in agreement with Lampert's theory. Illumination with photons in the extrinsic energy-range appears to increase considerably the amount of injected charge that remains free in the conduction band.

  2. Behaviour of bipolar membranes at high current density. Water diffusion limitation

    NARCIS (Netherlands)

    Krol, J.J.; Jansink, M.G.J.; Wessling, Matthias; Strathmann, H.

    1998-01-01

    In this paper the behaviour of bipolar membranes at very high current density is discussed. Current–voltage curves are determined, both for the Tokuyama Soda BP-1 and the WSI Technologies bipolar membrane. The current–voltage curves are characterised by an inflection point at which a drastic

  3. Current status data with competing risks: limiting distribution of the MLE

    NARCIS (Netherlands)

    Groeneboom, P.; Maathuis, M.H.; Wellner, J.A.

    2008-01-01

    We study nonparametric estimation for current status data with competing risks. Our main interest is in the nonparametric maximum likelihood estimator (MLE), and for comparison we also consider a simpler “naive estimator.” Groeneboom, Maathuis and Wellner [Ann. Statist. (2008) 36 1031–1063] proved t

  4. Prehospital Stroke Care : Limitations of Current Interventions and Focus on New Developments

    NARCIS (Netherlands)

    Yperzeele, Laetitia; Van Hooff, Robbert-Jan; De Smedt, Ann; Espinoza, Alexis Valenzuela; de Casseye, Rohny Van; Hubloue, Ives; De Keyser, Jacques; Brouns, Raf

    Background: The global burden of stroke is immense, both in medical and economic terms. With the aging population and the ongoing industrialization of the third world, stroke prevalence is expected to increase and will have a major effect on national health expenditures. Currently, the medical

  5. Experimental Investigation and Modelling for the Optimisation of Conduction Cooled HTS Hybrid Current Leads for SMES

    Institute of Scientific and Technical Information of China (English)

    2003-01-01

    It′s important that HTS tapes have lower thermal conductivity and higher transversal resistivity in order to reduce the heat leaks conducted along the tapes and AC losses in the high temperature superconducting system conduction-cooled by GM coolers. This paper presents an experimental investigation into the effects of pure Ag and AgAu alloys sheath materials on the properties of Bi(2223) multifilamentary tapes and the optimisation of conduction-cooled hybrid current leads made from copper and Bi(2223)/Ag or Bi(2223)/AgAu tapes. The thermal conductivity of the tapes were measured by cryogenic steady heat flux method and the resistance was measured by using standard DC four-probe method at low temperature. The results showed that the reduction of thermal conductivity by the addition of Au into the sheath material of Bi(2223) tapes was 650%, 750% and 850% lower than that of pure Ag sheathed Bi(2223) tapes and the increase of resistivity was 4.9, 10 and 19.4 times higher than that of pure Ag for the addition of 2.20%, 5.70% and 10.70%Au(atom ratio) respectively. And the study also attempts to optimise thermodynamically the conduction-cooled hybrid current lead by using a developed model, which took the irreversibility of commercial GM coolers, the contact resistance and thermal conductance into account. Predictions from the model showed that AgAu alloys were suitable candidate materials to replace Ag as sheath material of Bi(2223) tapes applied in HTS current leads. In addition, Bi(2223)/AgAu was a suitable material to be applied as the HTS section of hybrid current leads in conduction-cooled superconducting electric systems.

  6. 自收缩效应型液态金属限流器限流特性影响因素的研究%Study of Influence Factors on Current Limiting Characteristics of Self Pinch Effect Type Liquid Metal Current Limiter

    Institute of Scientific and Technical Information of China (English)

    刘懿莹; 吴翊; 荣命哲; 何海龙; 李阳; 刘宏

    2012-01-01

    The liquid metal current limiter(LMCL) based on self pinch effect has a good application prospect with the merits of self detection,self-healing property after fault exclusion,the environment friendly medium,simple design and small volume.In this paper,the influence factors on current limiting characteristics of LMCL was experimental investigated by measuring the circuit current and the arc voltage of LMCL under different conditions during the current limiting process,which provided reference for optimum design of LMCL structure.The experimental results indicate that the current limiting effect is improved with the reduction of pre arcing time and the increase of arc voltage,and the pre arcing time and arc voltage are influenced by the prospective short current and structure parameters,during the experiment.It was found that the arc pressure can adversely affect the current limiting characteristics under high current,so a structure with pressure release space was proposed to solve this problem;and the current limiting effect was improved effectively.%基于自收缩效应的液态金属限流器(liquid metal current limiter,LMCL)有自动检测限流、故障排除后可自恢复、填充介质对环境友好、结构简单以及体积小的独特优点,具有良好的应用前景。通过测量不同情况下限流过程回路电流以及LMCL的电弧电压,实验研究了LMCL限流特性的影响因素,为LMCL结构的优化设计提供参考依据。实验结果表明:LMCL的限流效果随着弧前时间的缩短以及电弧电压的上升而愈加明显,弧前时间和电弧电压受预期短路电流和LMCL结构参数的影响;同时实验过程中发现,大电流下电弧压力对LMCL限流性能会产生不利的影响,为解决此问题,提出了一种带有压力释放功能的限流器结构,可以有效地改善限流效果。

  7. Current limiting behavior in three-phase transformer-type SFCLs using an iron core according to variety of fault

    Science.gov (United States)

    Cho, Yong-Sun; Jung, Byung-Ik; Ha, Kyoung-Hun; Choi, Soo-Geun; Park, Hyoung-Min; Choi, Hyo-Sang

    To apply the superconducting fault current limiter (SFCL) to the power system, the reliability of the fault-current-limiting operation must be ensured in diverse fault conditions. The SFCL must also be linked to the operation of the high-speed recloser in the power system. In this study, a three-phase transformer-type SFCL, which has a neutral line to improve the simultaneous quench characteristics of superconducting elements, was manufactured to analyze the fault-current-limiting characteristic according to the single, double, and triple line-to-ground faults. The transformer-type SFCL, wherein three-phase windings are connected to one iron core, reduced the burden on the superconducting element as the superconducting element on the sound phase was also quenched in the case of the single line-to-ground fault. In the case of double or triple line-to-ground faults, the flux from the faulted phase winding was interlinked with other faulted or sound phase windings, and the fault-current-limiting rate decreased because the windings of three phases were inductively connected by one iron core.

  8. Noise in space-charge-limited current in a CdS-single crystal at low injection level

    NARCIS (Netherlands)

    Driedonks, F.

    1967-01-01

    Current noise spectra (25Hz–20MHz) of a CdS-diode, working under space-charge-limited conditions. show trapping noise at low frequencies and slightly suppressed noise in the upper frequency range. Suppression is relatively small due to the effect of traps.

  9. Experimental Study on Vortex-Induced Vibrations of Submarine Pipeline near Seabed Boundary in Ocean Currents

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Unlike most previous studies on vortex-induced vibrations of a cylinder far from a boundary, this paper focuses on the influences of close proximity of a submarine pipeline to a rigid seabed boundary upon the dynamic responses of the pipeline in ocean currents. The effects of gap-to-diameter ratio and those of the stability parameter on the amplitude and frequency responses of a pipeline are investigated experimentally with a novel hydro-elastic facility. A comparison is made between the present experimental results of the amplitude and frequency responses for the pipes with seabed boundary effects and those for wall-free cylinders given by Govardhan and Williamson (2000) and Anand (1985). The comparison shows that the close proximity of a pipeline to seabed has much influence on the vortex-induced vibrations of the pipeline. Both the width of the lock-in ranges in terms of Vr and the dimensionless amplitude ratio Amax/D become larger with the decrease of the gap-to-diameter ratio e/D. Moreover, the vibration of the pipeline becomes easier to occur and its amplitude response becomes more intensive with the decrease of the stability parameter, while the pipeline frequency responses are affected slightly by the stability parameter.

  10. Current Density Limitations in a Fast-Pulsed High-Voltage Diode

    Science.gov (United States)

    1992-06-01

    based on mass x acceleration - charge x E-field) - - -= qT (x)=-e rT(X) (19) dt M c M c where y ,ŕ /•/ 2/c ••V/c; t * time (S) e I electron charge I... Plasmaphysik IPP 4/250, September 1991. 6. Parker, R.K., Explosive Electron Emission and the Characteristics of High-Current Electron Flow, Air Force

  11. [Outpatient thoracic surgery: Evolution of the indications, current applications and limits].

    Science.gov (United States)

    Bagan, P; Berna, P; De Dominicis, F; Lafitte, S; Zaimi, R; Dakhil, B; Das Neves Pereira, J-C

    2016-12-01

    The objectives of outpatient surgery are to reduce the risks connected to hospitalization, to improve postoperative recovery and to decrease the health costs. Few studies have been performed in the field of thoracic surgery and there remains great scope for progress in outpatient lung surgery. The purpose of this article is to present a revue of the current situation and the prospects for the development of out patient thoracic surgery.

  12. Measures to observe the current dust emission limit; Massnahmen zur Einhaltung des aktuellen Staubemissionsgrenzwerts

    Energy Technology Data Exchange (ETDEWEB)

    Evard, Michael [Vattenfall Europe Waerme AG, Berlin (Germany). Betrieb Heizkraftwerk Moabit

    2011-07-01

    The paper describes the operational experience and optimisation approach for a hot electrostatic precipitator (ESP) with a flue gas temperature of approximately 350 C as part of a circulating fluidised bed (CFB) boiler. It is particularly dealing with fault finding and cleaning after 20 years of operation. From the beginning of January 2011, new laws have come into force regulating dust emission limits. Therefore, it was necessary that existing ESP systems operate optimally. The ESP is a part of a hard coal-fired CFB boiler. (orig.)

  13. Experimental determination of two-dimensional critical current density distribution in YBCO coated conductors

    Energy Technology Data Exchange (ETDEWEB)

    Amemiya, Naoyuki; Shinkai, Yoshichika [Faculty of Engineering, Yokohama National University, Tokiwadai, Hodogaya, Yokohama (Japan); Iijima, Yasuhiro; Kakimoto, Kazuomi; Takeda, Kaoru [Materials Research Laboratory, Fujikura Ltd., Kiba, Koto, Tokyo (Japan)

    2001-08-01

    The critical current density (J{sub c}) distribution in YBCO coated conductors is attracting interest from the viewpoint of its influence on their AC loss characteristics as well as from material science and process engineering. A two-dimensional J{sub c} distribution in a YBCO coated conductor made by the IBAD (ion-beam assisted deposition) and the PLD (pulse-laser deposition) method can be determined by the magnetic-knife method with spatial resolutions of 0.2 mm lateral and 10 mm longitudinal directions, respectively. In an up-to-date 80A-class YBCO coated conductor, the J{sub c} is relatively uniform in the central part and reaches mbox{l_brace}7$x$10{sup 9} A m{sup -2}, {r_brace} while the J{sub c} fluctuates spatially in the central part of a tape fabricated earlier and with less critical current. Near the edges of the tapes, the J{sub c} is higher or lower than in the central part and the experimentally determined J{sub c} distributions are far from uniform. This suggests that a presumption of a uniform J{sub c} for AC loss estimations is not always reasonable and can lead to a large error in the estimated AC losses. (author)

  14. Experimental and numerical assessment of low-frequency current distributions from UMTS and GSM mobile phones.

    Science.gov (United States)

    Gosselin, Marie-Christine; Kühn, Sven; Kuster, Niels

    2013-12-07

    The evaluation of the exposure from mobile communication devices requires consideration of electromagnetic fields (EMFs) over a broad frequency range from dc to GHz. Mobile phones in operation have prominent spectral components in the low-frequency (LF) and radio-frequency (RF) ranges. While the exposure to RF fields from mobile phones has been comprehensively assessed in the past, the LF fields have received much less attention. In this study, LF fields from mobile phones are assessed experimentally and numerically for the global system for mobile (GSM) and universal mobile telecommunications system (UMTS) communication systems and conclusions about the global (LF and RF) EMF exposure from both systems are drawn. From the measurements of the time-domain magnetic fields, it was found that the contribution from the audio signal at a normal speech level, i.e., -16 dBm0, is the same order of magnitude as the fields induced by the current bursts generated from the implementation of the GSM communication system at maximum RF output level. The B-field induced by currents in phones using the UMTS is two orders of magnitude lower than that induced by GSM. Knowing that the RF exposure from the UMTS is also two orders of magnitude lower than from GSM, it is now possible to state that there is an overall reduction of the exposure from this communication system.

  15. Numerical and experimental study of the interaction between two marine current turbines

    CERN Document Server

    Mycek, Paul; Germain, Grégory; Pinon, Grégory; Rivoalen, Elie

    2013-01-01

    The understanding of interaction effects between marine energy converters represents the next step in the research process that should eventually lead to the deployment of such devices. Although some a priori considerations have been suggested recently, very few real condition studies have been carried out concerning this issue. Trials were run on 1/30th scale models of three-bladed marine current turbine prototypes in a flume tank. The present work focuses on the case where a turbine is placed at different locations in the wake of a first one. The interaction effects in terms of performance and wake of the second turbine are examined and compared to the results obtained on the case of one single turbine. Besides, a three-dimensional software, based on a vortex method is currently being developed, and will be used in the near future to model more complex layouts. The experimental study shows that the second turbine is deeply affected by the presence of an upstream device and that a compromise between individu...

  16. Comparative study of superconducting fault current limiter both for LCC-HVDC and VSC-HVDC systems

    Science.gov (United States)

    Lee, Jong-Geon; Khan, Umer Amir; Lim, Sung-Woo; Shin, Woo-ju; Seo, In-Jin; Lee, Bang-Wook

    2015-11-01

    High Voltage Direct Current (HVDC) system has been evaluated as the optimum solution for the renewable energy transmission and long-distance power grid connections. In spite of the various advantages of HVDC system, it still has been regarded as an unreliable system compared to AC system due to its vulnerable characteristics on the power system fault. Furthermore, unlike AC system, optimum protection and switching device has not been fully developed yet. Therefore, in order to enhance the reliability of the HVDC systems mitigation of power system fault and reliable fault current limiting and switching devices should be developed. In this paper, in order to mitigate HVDC fault, both for Line Commutated Converter HVDC (LCC-HVDC) and Voltage Source Converter HVDC (VSC-HVDC) system, an application of resistive superconducting fault current limiter which has been known as optimum solution to cope with the power system fault was considered. Firstly, simulation models for two types of LCC-HVDC and VSC-HVDC system which has point to point connection model were developed. From the designed model, fault current characteristics of faulty condition were analyzed. Second, application of SFCL on each types of HVDC system and comparative study of modified fault current characteristics were analyzed. Consequently, it was deduced that an application of AC-SFCL on LCC-HVDC system with point to point connection was desirable solution to mitigate the fault current stresses and to prevent commutation failure in HVDC electric power system interconnected with AC grid.

  17. Comparison of experimental and theoretical reaction rail currents, rail voltages, and airgap fields for the linear induction motor research vehicle

    Science.gov (United States)

    Elliott, D. G.

    1977-01-01

    Measurements of reaction rail currents, reaction rail voltages, and airgap magnetic fields in tests of the Linear Induction Motor Research Vehicle (LIMRV) were compared with theoretical calculations from the mesh/matrix theory. It was found that the rail currents and magnetic fields predicted by the theory are within 20 percent of the measured currents and fields at most motor locations in most of the runs, but differ by as much as a factor of two in some cases. The most consistent difference is a higher experimental than theoretical magnetic field near the entrance of the motor and a lower experimental than theoretical magnetic field near the exit. The observed differences between the theoretical and experimental magnetic fields and currents do not account for the differences of as much as 26 percent between the theoretical and experimental thrusts.

  18. The impact of antiretroviral therapy in resource-limited settings and current HIV therapeutics.

    Science.gov (United States)

    Kumarasamy, N

    2016-04-01

    Four million people of the global total of 35 million with HIV infection are from South-East Asia. ART is currently utilized by 15 million people and has led to a dramatic decline in the mortality rate, including those in low- and middle-income countries. A reduction in sexually transmitted HIV and in comorbidities including tuberculosis has also followed. Current recommendations for the initiation of antiretroviral therapy in people who are HIV+ are essentially to initiate ART irrespective of CD4 cell count and clinical stage. The frequency of HIV testing should be culturally specific and based on the HIV incidence in different key populations but phasing in viral load technology in LMIC is an urgent priority and this needs resources and capacity. With the availability of simplified potent ART regimens, persons with HIV now live longer. The recent WHO treatment guidelines recommending routine HIV testing and earlier initiation of treatment should be the stepping stone for ending the AIDS epidemic and to meet the UNAIDS mission of 90*90*90.

  19. Visualization of the boiling phenomena and counter-current flow limit of annular heat pipe

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Guk; Kim, Kyung Mo; Jeong, Yeong Shin; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2015-10-15

    The thermal resistance of conventional heat pipes increases over the capillary limit because of the insufficient supplement of the working fluid. Due to the shortage of the liquid supplement, thermosyphon is widely used for vertically oriented heat transport and high heat load conditions. Thermosyphons are two-phase heat transfer devices that have the highly efficient heat transport from evaporation to condensation section that makes an upward driving force for vapor. In the condenser section, the vapor condenses and releases the latent heat. Due to the gravitation force acting on the liquid in the tube, working fluid back to the evaporator section, normally this process operate at the vertical and inclination position. The use of two-phase closed thermosyphon (TPCT) for the cooling devices has the limitation due to the phase change of the working fluid assisted by gravity force. Due to the complex phenomenon of two-phase flow, it is required to understand what happened in TPCT. The visualization of the thermosyphon and heat pipe is investigated for the decrease of thermal resistance and enhancement of operation limit. Weibel et al. investigated capillary-fed boiling of water with porous sintered powder wick structure using high speed camera. At the high heat flux condition, dry-out phenomenon and a thin liquid film are observed at the porous wick structure. Wong and Kao investigated the evaporation and boiling process of mesh wicked heat pipe using optical camera. At the high heat flux condition, the water filing became thin and partial dry-out was observed in the evaporator section. Our group suggested the concept of a hybrid heat pipe with control rod as Passive IN-core Cooling System (PINCs) for decay heat removal for advanced nuclear power plant. The hybrid heat pipe is the combination of the heat pipe and control rod. It is necessary for PINCs to contain a neutron absorber (B{sub 4}C) to have the ability of reactivity control. It has annular vapor space and

  20. Upgrade of the Gas Flow Control System of the Resistive Current Leads of the LHC Inner Triplet Magnets: Simulation and Experimental Validation

    CERN Document Server

    Perin, A; Casas-Cubillos, J; Pezzetti, M

    2014-01-01

    The 600 A and 120 A circuits of the inner triplet magnets of the Large Hadron Collider are powered by resistive gas cooled current leads. The current solution for controlling the gas flow of these leads has shown severe operability limitations. In order to allow a more precise and more reliable control of the cooling gas flow, new flowmeters will be installed during the first long shutdown of the LHC. Because of the high level of radiation in the area next to the current leads, the flowmeters will be installed in shielded areas located up to 50 m away from the current leads. The control valves being located next to the current leads, this configuration leads to long piping between the valves and the flowmeters. In order to determine its dynamic behaviour, the proposed system was simulated with a numerical model and validated with experimental measurements performed on a dedicated test bench.

  1. Biasing, operation and parasitic current limitation in single device equivalent to CMOS, and other semiconductor systems

    Science.gov (United States)

    Welch, James D.

    2003-09-23

    Disclosed are semiconductor devices including at least one junction which is rectifying whether the semiconductor is caused to be N or P-type, by the presence of applied gate voltage field induced carriers in essentially intrinsic, essentially homogeneously simultaneously containing both N and P-type metallurgical dopants at substantially equal doping levels, essentially homogeneously simultaneously containing both N and P-type metallurgical dopants at different doping levels, and containing a single metallurgical doping type, and functional combinations thereof. In particular, inverting and non-inverting gate voltage channel induced semiconductor single devices with operating characteristics similar to conventional multiple device CMOS systems, which can be operated as modulators, are disclosed as are a non-latching SCR and an approach to blocking parasitic currents utilizing material(s) which form rectifying junctions with both N and P-type semiconductor whether metallurigically or field induced.

  2. Invited review current progress and limitations of spider silk for biomedical applications.

    Science.gov (United States)

    Widhe, Mona; Johansson, Jan; Hedhammar, My; Rising, Anna

    2012-06-01

    Spider silk is a fascinating material combining remarkable mechanical properties with low density and biodegradability. Because of these properties and historical descriptions of medical applications, spider silk has been proposed to be the ideal biomaterial. However, overcoming the obstacles to produce spider silk in sufficient quantities and in a manner that meets regulatory demands has proven to be a difficult task. Also, there are relatively few studies of spider silk in biomedical applications available, and the methods and materials used vary a lot. Herein we summarize cell culture- and in vivo implantation studies of natural and synthetic spider silk, and also review the current status and future challenges in the quest for a large scale production of spider silk for medical applications. Copyright © 2011 Wiley Periodicals, Inc.

  3. Theoretical and experimental implementation of vibrational resonance in an array of hard limiters

    Science.gov (United States)

    Ren, Yuhao; Duan, Fabing

    2016-08-01

    We report that the output signal-to-noise ratio (SNR) of a parallel array of hard limiters can be maximized at an optimal high-frequency vibration amplitude, i.e. the vibrational resonance (VR) effect. As the external noise shape parameter varies, the bifurcation mode of maximal SNR gain is found, and the upper limit of SNR gain is discussed. We theoretically demonstrate a tractable realization of an infinite array approached by a finite array of two hard limiters, and design an electronic circuit experiment to verify the feasibility of this effective method. These results indicate the potential applications of vibrational devices to array signal processing.

  4. Experimental study of limit lean methane/air flame in a standard flammability tube using particle image velocimetry method

    Energy Technology Data Exchange (ETDEWEB)

    Shoshin, Yuriy; Gorecki, Grzegorz; Jarosinski, Jozef; Fodemski, Tadeusz [Department of Heat Technology and Refrigeration, Technical University of Lodz, Lodz 90-924 (Poland)

    2010-05-15

    Lean limit methane/air flame propagating upward in a standard 50 mm diameter and 1.8 m length tube was studied experimentally using particle image velocimetry method. Local stretch rate along the flame front was determined by measured gas velocity distributions. It was found that local stretch rate is maximum at the flame leading point, which is in agreement with earlier theoretical results. Similar to earlier observations, extinction of upward propagating limit flame was observed to start from the flame top. It is stated that the observed behavior of the extinction of the lean limit methane/air flame can not be explained in terms of the coupled effect of flame stretch and preferential diffusion. To qualitatively explain the observed extinction behavior, it is suggested that the positive strain-induced flame stretch increases local radiation heat losses from the flame front. An experimental methodology for PIV measurements in a round tube is described. (author)

  5. Two-phase flow experiments on Counter-Current Flow Limitation in a model of the hot leg of a pressurized water reactor (2015 test series)

    Energy Technology Data Exchange (ETDEWEB)

    Beyer, Matthias; Lucas, Dirk; Pietruske, Heiko; Szalinski, Lutz

    2016-12-15

    Counter-Current Flow Limitation (CCFL) is of importance for PWR safety analyses in several accident scenarios connected with loss of coolant. Basing on the experiences obtained during a first series of hot leg tests now new experiments on counter-current flow limitation were conducted in the TOPFLOW pressure vessel. The test series comprises air-water tests at 1 and 2 bar as well as steam-water tests at 10, 25 and 50 bar. During the experiments the flow structure was observed along the hot leg model using a high-speed camera and web-cams. In addition pressure was measured at several positions along the horizontal part and the water levels in the reactor-simulator and steam-generator-simulator tanks were determined. This report documents the experimental setup including the description of operational and special measuring techniques, the experimental procedure and the data obtained. From these data flooding curves were obtained basing on the Wallis parameter. The results show a slight shift of the curves in dependency of the pressure. In addition a slight decrease of the slope was found with increasing pressure. Additional investigations concern the effects of hysteresis and the frequencies of liquid slugs. The latter ones show a dependency on pressure and the mass flow rate of the injected water. The data are available for CFD-model development and validation.

  6. Experimental Investigation on Limit Cycle Wing Rock Effect on Wing Body Configuration Induced by Forebody Vortices

    National Research Council Canada - National Science Library

    Rong, Zhen; Deng, Xueying; Ma, Baofeng; Wang, Bing

    2016-01-01

    ...° swept wing configuration undergoing a limit cycle oscillation using a synchronous measurement and control technique of wing rock/particle image velocimetry/dynamic pressure associated with the time...

  7. Scanning fast and slow: current limitations of 3 Tesla functional MRI and future potential

    Science.gov (United States)

    Boubela, Roland N.; Kalcher, Klaudius; Nasel, Christian; Moser, Ewald

    2014-02-01

    Functional MRI at 3T has become a workhorse for the neurosciences, e.g., neurology, psychology, and psychiatry, enabling non-invasive investigation of brain function and connectivity. However, BOLD-based fMRI is a rather indirect measure of brain function, confounded by fluctuation related signals, e.g. head or brain motion, brain pulsation, blood flow, intermixed with susceptibility differences close or distant to the region of neuronal activity. Even though a plethora of preprocessing strategies have been published to address these confounds, their efficiency is still under discussion. In particular, physiological signal fluctuations closely related to brain supply may mask BOLD signal changes related to "true" neuronal activation. Here we explore recent technical and methodological advancements aimed at disentangling the various components, employing fast multiband vs. standard EPI, in combination with fast temporal ICA.Our preliminary results indicate that fast (TRbrain, even at a rather coarse macroscopic level, we should be very cautious in the interpretation of neuroscientific findings, in particular when comparing different groups (e.g., age, sex, medication, pathology, etc.). From a technical point of view our goal should be to sample brain activity at layer specific resolution with low TR, covering as much of the brain as possible without violating SAR limits. We hope to stimulate discussion towards a better understanding and a more quantitative use of fMRI.

  8. Human immune system mice: current potential and limitations for translational research on human antibody responses.

    Science.gov (United States)

    Vuyyuru, Raja; Patton, John; Manser, Tim

    2011-12-01

    It has recently become possible to generate chimeric mice durably engrafted with many components of the human immune system (HIS mice). We have characterized the maturation and function of the B cell compartment of HIS mice. The antibody response of HIS mice to T cell-dependent B cell antigens is limited, and contributing factors may be the general immaturity of the B cell compartment, infrequent helper T cells selected on human MHC class II antigens, and incomplete reconstitution of secondary lymphoid organs and their microenvironments. In contrast, HIS mice generate protective antibody responses to the bacterium Borrelia hermsii, which acts as a T cell-independent antigen in mice, but do not respond to purified polysaccharide antigens (PPS). We speculate that the anti-B. hermsii response of HIS mice is derived from an abundant B cell subset that may be analogous to B1 B cells in mice. We suggest that failure of HIS mice to respond to PPS is due to the lack of a B cell subset that may originate from adult bone marrow and is highly dependent on human interleukin-7 for development.

  9. Four point function of R-currents in N=4 SYM in the Regge limit at weak coupling

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, J.; Mischler, A.M.; Salvadore, M. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik

    2008-04-15

    We compute, in N = 4 super Yang-Mills, the four point correlation function of R-currents in the Regge limit in the leading logarithmic approximation at weak coupling. Such a correlator is the closest analog to photon-photon scattering within QCD, and there is a well defined procedure to perform the analogous computation at strong coupling via AdS/CFT. The main result of this paper is, on the gauge theory side, the proof of Regge factorization and the explicit computation of the R-current impact factors. (orig.)

  10. Theoretical Limit to the Laser Threshold Current Density in an InGaN Quantume Well Laser

    Energy Technology Data Exchange (ETDEWEB)

    Amano, H; Chow, W W; Han, J

    1998-10-09

    This paper describes an investigation of the spontaneous emission limit to the laser threshold current density in an InGaN quantum well laser. The peak gain and spontaneous emission rate as functions of carrier density are com- puted using a microscopic laser theory. From these quantities, the minimum achievable threshold current density is determined for a given threshold gain. The dependence on quantum well width, and the effects of inhomogeneous broadening due to spatial alloy variations are discussed. Also, comparison with experiments is made.

  11. DWPF COAL-CARBON WASTE ACCEPTANCE CRITERIA LIMIT EVALUATION BASED ON EXPERIMENTAL WORK (TANK 48 IMPACT STUDY)

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D.; Choi, A.

    2010-10-15

    This report summarizes the results of both experimental and modeling studies performed using Sludge Batch 10 (SB10) simulants and FBSR product from Tank 48 simulant testing in order to develop higher levels of coal-carbon that can be managed by DWPF. Once the Fluidized Bed Steam Reforming (FBSR) process starts up for treatment of Tank 48 legacy waste, the FBSR product stream will contribute higher levels of coal-carbon in the sludge batch for processing at DWPF. Coal-carbon is added into the FBSR process as a reductant and some of it will be present in the FBSR product as unreacted coal. The FBSR product will be slurried in water, transferred to Tank Farm and will be combined with sludge and washed to produce the sludge batch that DWPF will process. The FBSR product is high in both water soluble sodium carbonate and unreacted coal-carbon. Most of the sodium carbonate is removed during washing but all of the coal-carbon will remain and become part of the DWPF sludge batch. A paper study was performed earlier to assess the impact of FBSR coal-carbon on the DWPF Chemical Processing Cell (CPC) operation and melter off-gas flammability by combining it with SB10-SB13. The results of the paper study are documented in Ref. 7 and the key findings included that SB10 would be the most difficult batch to process with the FBSR coal present and up to 5,000 mg/kg of coal-carbon could be fed to the melter without exceeding the off-gas flammability safety basis limits. In the present study, a bench-scale demonstration of the DWPF CPC processing was performed using SB10 simulants spiked with varying amounts of coal, and the resulting seven CPC products were fed to the DWPF melter cold cap and off-gas dynamics models to determine the maximum coal that can be processed through the melter without exceeding the off-gas flammability safety basis limits. Based on the results of these experimental and modeling studies, the presence of coal-carbon in the sludge feed to DWPF is found to have

  12. 故障电流限制器发展现状与应用前景%Current Status and Application Prospect of Fault Current Limiters

    Institute of Scientific and Technical Information of China (English)

    郑健超

    2014-01-01

    To meet the challenge of ever-increasing fault current level in the power grid, various fault current limiters have been proposed and developed over the past decades. However, with a few exceptions, there has been little progress in developing products feasible for commercial applications. This paper attempts to give an overview of current states and technical features of the leading fault current limiters, and to analyze the restrictions to its penetration into power market. Finally, the development trend and future prospect of FCL are projected, with special reference to the recent innovation tendency in making FCL more competitive, including extending its applications to smart grid and further improving its tech-economic performance by technology convergence.%为了应对电网故障电流水平日益增长的挑战,过去数十年,提出并开发了各类故障电流限制器。但是,除少数例外,适合于商业应用的产品开发却进展缓慢。该文概括介绍了主要限流器的发展现状及技术特点,分析了影响限流器进入电力市场的制约因素。最后,预测了限流器的发展趋势和未来前景,重点讲述为提高限流器的竞争力,近年来技术创新的趋向,包括将限流器的应用扩展到智能电网,通过技术融合进一步改善其技术经济性能等。

  13. 14 CFR 91.319 - Aircraft having experimental certificates: Operating limitations.

    Science.gov (United States)

    2010-01-01

    ... or hire. (b) No person may operate an aircraft that has an experimental certificate outside of an...— (1) Tow a glider that is a light-sport aircraft or unpowered ultralight vehicle in accordance with... glider that is a light-sport aircraft or unpowered ultralight vehicle for compensation or hire or...

  14. Fault ride-through enhancement of fixed speed wind turbine using bridge-type fault current limiter

    Directory of Open Access Journals (Sweden)

    Mostafa I. Marei

    2016-05-01

    Full Text Available The interaction between wind energy turbines and the grid results in two main problems, increasing the short-circuit level and reducing the Fault Ride-Through (FRT capability during faults. The objective of this paper is to solve these problems, for fixed speed Wind Energy Systems (WECS, utilizing the bridge-type Fault Current Limiter (FCL with a discharging resistor. A simple cascaded control system is proposed for the FCL to regulate the terminal voltage of the generator and limit the current. The system is simulated on PSCAD/EMTDC software to evaluate the dynamic performance of the proposed WECS compensated by FCL. The simulation results show the potentials of the FCL as a simple and effective method for solving grid interconnection problems of WECS.

  15. 基于限流电抗电流控制的新型桥式固态限流器%A Novel Bridge-Type Solid-State Fault Current Limiter Based on Limiting Reactance Current Control

    Institute of Scientific and Technical Information of China (English)

    范宇; 江道灼; 吕文韬

    2014-01-01

    On the basis of thyristors based single-phase/three-phase bridge-type solid-state fault current limiter (SSFCL), its topological structure is improved:thyristors in rectifier and freewheel bridges are substituted by diodes to decrease the number of power electronic controllable elements. A limiting reactance current control based control strategy is proposed, that is, through controlling the switching off/on of full-controllable power electronic switch elements in current limiting reactance branch the current flowing through current limiting reactance is kept stable to limit the amplitude of fault current in transmission line. The analysis on entire working process of the improved SSFCL is given. Based on the topological structure and working principle, the control system and element parameters are designed and corresponding simulation model is established. Simulation results show that under different fault conditions the improved SSFCL works correctly and slightly affects on non-fault phase;it can control fault current accurately and the value of limited current can be flexible regulated, so after the clearance of the fault the transmission line can be back to normal operation rapidly, besides the improve SSFCL is suitable for following conditions:many times of fault occurred in a short-term, non-full-phase operation of transmission line and automatic reclosure.%在基于晶闸管的单相/三相桥式固态限流器基础上,对其拓扑结构进行改进,其中整流桥路、续流桥路均采用二极管,减少电力电子可控元件的数量。提出了基于限流电抗电流控制的控制策略,通过控制限流电抗支路的全控电力电子开关器件的关断与导通,保持限流电抗电流稳定,限制线路故障电流的幅值,并对整个工作过程给出了完整分析。根据拓扑结构与工作原理,对控制系统与元件参数进行设计并进行建模仿真。结果表明该限流器正确工作于不同故障且

  16. A trap-limited-current-based model of Meyer-Neldel rule and its connection to persistent photocurrent

    Science.gov (United States)

    Tian, Ye; Jiang, Lianjun; Zhang, Xuejun; Zhang, Guangfu

    2016-10-01

    A theoretical model is established to describe the emergence of the Meyer-Neldel rule (MNR) based on trap-limited current (TLC) theory. The model produces both MNR and anti-MNR behavior, and is available to various trap distributions. Moreover, TLC-based MNR is connected to persistent photocurrent (PPC) phenomenon. The information from MNR and PPC as well as their connection can be used to probe the distribution of the traps in materials.

  17. Some current problems in perovskite nano-ferroelectrics and multiferroics: kinetically-limited systems of finite lateral size

    Science.gov (United States)

    Scott, James F.; Schilling, Alina; Rowley, S. E.; Gregg, J. Marty

    2015-06-01

    We describe some unsolved problems of current interest; these involve quantum critical points in ferroelectrics and problems which are not amenable to the usual density functional theory, nor to classical Landau free energy approaches (they are kinetically limited), nor even to the Landau-Kittel relationship for domain size (they do not satisfy the assumption of infinite lateral diameter) because they are dominated by finite aperiodic boundary conditions.

  18. Current Parental Depression and Offspring Perceived Self-Competence: A Quasi-Experimental Examination

    Science.gov (United States)

    Class, Quetzal A.; D’Onofrio, Brian M.; Singh, Amber L.; Ganiban, Jody M.; Spotts, E. L.; Lichtenstein, Paul; Reiss, David; Neiderhiser, Jenae M.

    2013-01-01

    A genetically-informed, quasi-experimental design was used to examine the genetic and environmental processes underlying associations between current parental depressive symptoms and offspring perceived self-competence. Participants, drawn from a population-based Swedish sample, were 852 twin pairs and their male (52%) and female offspring aged 15.7 ± 2.4 years. Parental depressive symptoms were measured using the Center for Epidemiological Studies Depression scale. Offspring perceived self-competence was measured using a modified Harter Perceived Competence Scale. Cousin comparisons and Children of Twins (CoT) designs suggested that associations between maternal depressive symptoms and offspring perceived self-competence were due to shared genetic/environmental liability. The mechanism responsible for father-offspring associations, however, was independent of genetic factors and of extended-family environmental factors, supporting a causal inference. Thus, mothers and fathers may impact offspring perceived self-competence via different mechanisms and unmeasured genetic and environmental selection factors must be considered when studying the intergenerational transmission of cognitive vulnerabilities for depression. PMID:22692226

  19. Comparison of experimental and theoretical gain-current relations in GaInP quantum well lasers

    Energy Technology Data Exchange (ETDEWEB)

    Smowton, P.M.; Chow, W.W.; Blood, P.

    2000-01-10

    The authors compare the results of a microscopic laser theory with gain and recombination currents obtained from experimental spontaneous emission spectra. The calculated absorption spectrum is first matched to that measured on a laser, ensuring that the quasi-Fermi levels for the calculation and the experiment (spontaneous emission and gain) are directly related. This allows one to determine the inhomogeneous broadening in their experimental samples. The only other inputs to the theory are literature values of the bulk material parameter. The authors then estimate the non-radiative recombination current associated with the well and wave-guide core from a comparison of measured and calculated recombination currents.

  20. Stochastic dynamics of extended objects in driven systems II: Current quantization in the low-temperature limit

    Science.gov (United States)

    Catanzaro, Michael J.; Chernyak, Vladimir Y.; Klein, John R.

    2016-12-01

    Driven Langevin processes have appeared in a variety of fields due to the relevance of natural phenomena having both deterministic and stochastic effects. The stochastic currents and fluxes in these systems provide a convenient set of observables to describe their non-equilibrium steady states. Here we consider stochastic motion of a (k - 1) -dimensional object, which sweeps out a k-dimensional trajectory, and gives rise to a higher k-dimensional current. By employing the low-temperature (low-noise) limit, we reduce the problem to a discrete Markov chain model on a CW complex, a topological construction which generalizes the notion of a graph. This reduction allows the mean fluxes and currents of the process to be expressed in terms of solutions to the discrete Supersymmetric Fokker-Planck (SFP) equation. Taking the adiabatic limit, we show that generic driving leads to rational quantization of the generated higher dimensional current. The latter is achieved by implementing the recently developed tools, coined the higher-dimensional Kirchhoff tree and co-tree theorems. This extends the study of motion of extended objects in the continuous setting performed in the prequel (Catanzaro et al.) to this manuscript.

  1. Stochastic Dynamics of Extended Objects in Driven Systems II: Current Quantization in the Low-Temperature Limit

    CERN Document Server

    Catanzaro, Michael J; Klein, John R

    2016-01-01

    Driven Langevin processes have appeared in a variety of fields due to the relevance of natural phenomena having both deterministic and stochastic effects. The stochastic currents and fluxes in these systems provide a convenient set of observables to describe their non-equilibrium steady states. Here we consider stochastic motion of a (k - 1)-dimensional object, which sweeps out a k-dimensional trajectory, and gives rise to a higher k-dimensional current. By employing the low-temperature (low-noise) limit, we reduce the problem to a discrete Markov chain model on a CW complex, a topological construction which generalizes the notion of a graph. This reduction allows the mean fluxes and currents of the process to be expressed in terms of solutions to the discrete Supersymmetric Fokker-Planck (SFP) equation. Taking the adiabatic limit, we show that generic driving leads to rational quantization of the generated higher dimensional current. The latter is achieved by implementing the recently developed tools, coined...

  2. Modeling of contact mechanics and friction limit surfaces for soft fingers in robotics, with experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Xydas, N.; Kao, I.

    1999-09-01

    A new theory in contact mechanics for modeling of soft fingers is proposed to define the relationship between the normal force and the radius of contact for soft fingers by considering general soft-finger materials, including linearly and nonlinearly elastic materials. The results show that the radius of contact is proportional to the normal force raised to the power of {gamma}, which ranges from 0 to 1/3. This new theory subsumes the Hertzian contact model for linear elastic materials, where {gamma} = 1/3. Experiments are conducted to validate the theory using artificial soft fingers made of various materials such as rubber and silicone. Results for human fingers are also compared. This theory provides a basis for numerically constructing friction limit surfaces. The numerical friction limit surface can be approximated by an ellipse, with the major and minor axes as the maximum friction force and the maximum moment with respect to the normal axis of contact, respectively. Combining the results of the contact-mechanics model with the contact-pressure distribution, the normalized friction limit surface can be derived for anthropomorphic soft fingers. The results of the contact-mechanics model and the pressure distribution for soft fingers facilitate the construction of numerical friction limit surfaces, and will enable us to analyze and simulate contact behaviors of grasping and manipulation in robotics.

  3. Flammability limits in flowing ethene-air-nitrogen mixtures: an experimental study

    NARCIS (Netherlands)

    Bolk, J.W.; Siccama, N.B.; Westerterp, K.R.

    1996-01-01

    A large pilot plant was constructed to study the upper flammability limit of ethene-air-nitrogen mixtures under conditions of flow. The gas mixtures flowed through an explosion tube with a length of 3.0 m and a diameter of 21 mm. An electrically heated wire was used as ignition source. Experiments w

  4. Surgical Simulations Based on Limited Quantitative Data: Understanding How Musculoskeletal Models Can Be Used to Predict Moment Arms and Guide Experimental Design.

    Science.gov (United States)

    Nichols, Jennifer A; Bednar, Michael S; Murray, Wendy M

    2016-01-01

    The utility of biomechanical models and simulations to examine clinical problems is currently limited by the need for extensive amounts of experimental data describing how a given procedure or disease affects the musculoskeletal system. Methods capable of predicting how individual biomechanical parameters are altered by surgery are necessary for the efficient development of surgical simulations. In this study, we evaluate to what extent models based on limited amounts of quantitative data can be used to predict how surgery influences muscle moment arms, a critical parameter that defines how muscle force is transformed into joint torque. We specifically examine proximal row carpectomy and scaphoid-excision four-corner fusion, two common surgeries to treat wrist osteoarthritis. Using models of these surgeries, which are based on limited data and many assumptions, we perform simulations to formulate a hypothesis regarding how these wrist surgeries influence muscle moment arms. Importantly, the hypothesis is based on analysis of only the primary wrist muscles. We then test the simulation-based hypothesis using a cadaveric experiment that measures moment arms of both the primary wrist and extrinsic thumb muscles. The measured moment arms of the primary wrist muscles are used to verify the hypothesis, while those of the extrinsic thumb muscles are used as cross-validation to test whether the hypothesis is generalizable. The moment arms estimated by the models and measured in the cadaveric experiment both indicate that a critical difference between the surgeries is how they alter radial-ulnar deviation versus flexion-extension moment arms at the wrist. Thus, our results demonstrate that models based on limited quantitative data can provide novel insights. This work also highlights that synergistically utilizing simulation and experimental methods can aid the design of experiments and make it possible to test the predictive limits of current computer simulation techniques.

  5. The Current State of Knowledge of Hepatic Ischemia-Reperfusion Injury Based on Its Study in Experimental Models

    Science.gov (United States)

    Mendes-Braz, M.; Elias-Miró, M.; Jiménez-Castro, M. B.; Casillas-Ramírez, A.; Ramalho, F. S.; Peralta, C.

    2012-01-01

    The present review focuses on the numerous experimental models used to study the complexity of hepatic ischemia/reperfusion (I/R) injury. Although experimental models of hepatic I/R injury represent a compromise between the clinical reality and experimental simplification, the clinical transfer of experimental results is problematic because of anatomical and physiological differences and the inevitable simplification of experimental work. In this review, the strengths and limitations of the various models of hepatic I/R are discussed. Several strategies to protect the liver from I/R injury have been developed in animal models and, some of these, might find their way into clinical practice. We also attempt to highlight the fact that the mechanisms responsible for hepatic I/R injury depend on the experimental model used, and therefore the therapeutic strategies also differ according to the model used. Thus, the choice of model must therefore be adapted to the clinical question being answered. PMID:22649277

  6. Comparative study of superconducting fault current limiter both for LCC-HVDC and VSC-HVDC systems

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jong-Geon; Khan, Umer Amir; Lim, Sung-Woo; Shin, Woo-ju; Seo, In-Jin; Lee, Bang-Wook, E-mail: bangwook@hanyang.ac.kr

    2015-11-15

    Highlights: • The role of SFCL in types of HVDC system was evaluated. • A simulation model based on Korea Jeju–Haenam HVDC power system was designed in Matlab/Simulink. • Utilizing the designed both HVDC power system models, the efficiency of DC-SFCL was relatively low, compared to AC-SFCL. • It was deduced that the AC-SFCL was more effective in LCC-HVDC system than VSC-HVDC system. - Abstract: High Voltage Direct Current (HVDC) system has been evaluated as the optimum solution for the renewable energy transmission and long-distance power grid connections. In spite of the various advantages of HVDC system, it still has been regarded as an unreliable system compared to AC system due to its vulnerable characteristics on the power system fault. Furthermore, unlike AC system, optimum protection and switching device has not been fully developed yet. Therefore, in order to enhance the reliability of the HVDC systems mitigation of power system fault and reliable fault current limiting and switching devices should be developed. In this paper, in order to mitigate HVDC fault, both for Line Commutated Converter HVDC (LCC-HVDC) and Voltage Source Converter HVDC (VSC-HVDC) system, an application of resistive superconducting fault current limiter which has been known as optimum solution to cope with the power system fault was considered. Firstly, simulation models for two types of LCC-HVDC and VSC-HVDC system which has point to point connection model were developed. From the designed model, fault current characteristics of faulty condition were analyzed. Second, application of SFCL on each types of HVDC system and comparative study of modified fault current characteristics were analyzed. Consequently, it was deduced that an application of AC-SFCL on LCC-HVDC system with point to point connection was desirable solution to mitigate the fault current stresses and to prevent commutation failure in HVDC electric power system interconnected with AC grid.

  7. Current experimental perspectives on the clinical progression of alcoholic liver disease.

    Science.gov (United States)

    Breitkopf, Katja; Nagy, Laura E; Beier, Juliane I; Mueller, Sebastian; Weng, Honglei; Dooley, Steven

    2009-10-01

    Chronic alcohol abuse is an important cause of morbidity and mortality throughout the world. Liver damage due to chronic alcohol intoxication initially leads to accumulation of lipids within the liver and with ongoing exposure this condition of steatosis may first progress to an inflammatory stage which leads the way for fibrogenesis and finally cirrhosis of the liver. While the earlier stages of the disease are considered reversible, cirrhotic destruction of the liver architecture beyond certain limits causes irreversible damage of the organ and often represents the basis for cancer development. This review will summarize current knowledge about the molecular mechanisms underlying the different stages of alcoholic liver disease (ALD). Recent observations have led to the identification of new molecular mechanisms and mediators of ALD. For example, plasminogen activator inhibitor 1 was shown to play a central role for steatosis, the anti-inflammatory adipokine, adiponectin profoundly regulates liver macrophage function and excessive hepatic deposition of iron is caused by chronic ethanol intoxication and increases the risk of hepatocellular carcinoma development.

  8. Structural Characterization of Phase Separation in Fe-Cr: A Current Comparison of Experimental Methods

    Science.gov (United States)

    Xu, Xin; Odqvist, Joakim; Colliander, Magnus Hörnqvist; Thuvander, Mattias; Steuwer, Axel; Westraadt, Johan E.; King, Stephen; Hedström, Peter

    2016-12-01

    Self-assembly due to phase separation within a miscibility gap is important in numerous material systems and applications. A system of particular interest is the binary alloy system Fe-Cr, since it is both a suitable model material and the base system for the stainless steel alloy category, suffering from low-temperature embrittlement due to phase separation. Structural characterization of the minute nano-scale concentration fluctuations during early phase separation has for a long time been considered a major challenge within material characterization. However, recent developments present new opportunities in this field. Here, we present an overview of the current capabilities and limitations of different techniques. A set of Fe-Cr alloys were investigated using small-angle neutron scattering (SANS), atom probe tomography, and analytical transmission electron microscopy. The complementarity of the characterization techniques is clear, and combinatorial studies can provide complete quantitative structure information during phase separation in Fe-Cr alloys. Furthermore, we argue that SANS provides a unique in-situ access to the nanostructure, and that direct comparisons between SANS and phase-field modeling, solving the non-linear Cahn Hilliard equation with proper physical input, should be pursued.

  9. Solid-State Fault Current Limiter Development : Design and Testing Update of a 15kV SSCL Power Stack

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Ram Adapa; Mr. Dante Piccone

    2012-04-30

    ABSTRACT The Solid-State Fault Current Limiter (SSCL) is a promising technology that can be applied to utility power delivery systems to address the problem of increasing fault currents associated with load growth. As demand continues to grow, more power is added to utility system either by increasing generator capacity or by adding distributed generators, resulting in higher available fault currents, often beyond the capabilities of the present infrastructure. The SSCL is power-electronics based equipment designed to work with the present utility system to address this problem. The SSCL monitors the line current and dynamically inserts additional impedance into the line in the event of a fault being detected. The SSCL is based on a modular design and can be configured for 5kV through 69kV systems at nominal current ratings of 1000A to 4000A. Results and Findings This report provides the final test results on the development of 15kV class SSCL single phase power stack. The scope of work included the design of the modular standard building block sub-assemblies, the design and manufacture of the power stack and the testing of the power stack for the key functional tests of continuous current capability and fault current limiting action. Challenges and Objectives Solid-State Current Limiter technology impacts a wide spectrum of utility engineering and operating personnel. It addresses the problems associated with load growth both at Transmission and Distribution class networks. The design concept is pioneering in terms of developing the most efficient and compact power electronics equipment for utility use. The initial test results of the standard building blocks are promising. The independent laboratory tests of the power stack are promising. However the complete 3 phase system needs rigorous testing for performance and reliability. Applications, Values, and Use The SSCL is an intelligent power-electronics device which is modular in design and can provide current

  10. Coherent imaging at resolution beyond diffraction limit using post-experimental data extrapolation

    CERN Document Server

    Latychevskaia, Tatiana

    2013-01-01

    Classical microscopy, regardless if photons or electrons are used, is based on incoherent optics and the microscopic record represents a distribution of added intensities. Local information of the sample is thus mapped onto local information at the detector. The resultant image exhibits a resolution ultimately limited by the Abbe criterion respectively by the numerical aperture of the microscope for a given wavelength. A number of super-resolution techniques in near as well as in the far-field have been proposed which allow imaging beyond the Abbe resolution limit. In contrast to classical optical microscopy in coherent microscopy, like holography or coherent diffraction, the superposition principle of waves holds, implying that field amplitudes are added, not intensities. The superposition of waves, be it light or deBroglie waves, leads to a non-local representation of the microscopic object information, an interference pattern spread out in space beyond the scattering object. Here we show a novel super-reso...

  11. Theoretical and experimental limitations of accelerometric measurements of vibrational intensity in beams

    Science.gov (United States)

    Carniel, Xavier

    1988-06-01

    Error sources and their influence on the precision of bending wave measurements of beams are reviewed. Optimal transducer spacings for various wavelengths and structure geometries are presented. It is found that the accuracy of the transducers is limited primarily by phase mismatch, particularly in low-frequency regions where phase gradients are weak. Problems in the phase calibration of accelerometers are pointed out. The results allow spatial and frequency parameters to be determined for a given structure and required measurement precision.

  12. Experimental study of a high-current FEM with a broadband microwave system

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, G.G.; Bratman, V.L.; Ginzburg, N.S. [Institute of Applied Physics, Nizhny Novgorod (Russian Federation)] [and others

    1995-12-31

    One of the main features of FELs and FEMs is the possibility of fast and wideband tuning of the resonant frequency of active media, which can be provided by changing the particle energy. For a frequency adjustable FEM-oscillator, a broadband microwave system, which is simply combined with an electron-optical FEM system and consists of an oversized waveguide and reflectors based on the microwave beams multiplication effect has been proposed and studied successfully in {open_quotes}cold{close_quotes} measurements. Here, the operating ability of a cavity, that includes some key elements of the broadband microwave system, was tested in the presence of an electron beam. To provide large particle oscillation velocities in a moderate undulator field and the presence of a guide magnetic field, the FEM operating regime of double resonance was chosen. In this regime the cyclotron as well as undulator resonance conditions were satisfied. The FEM-oscillator was investigated experimentally on a high-current accelerator {open_quotes}Sinus-6{close_quotes} that forms an electron beam with particle energy 500keV and pulse duration 25ns. The aperture with a diameter 2.5mm at the center of the anode allows to pass through only the central fraction of the electron beam with a current about 100A and a small spread of longitudinal velocities of the particles. Operating transverse velocity was pumped into the electron beam in the pulse plane undulator of a 2.4cm period. The cavity with a frequency near 45GHz consists of a square waveguide and two reflectors. The broadband up-stream reflector based on the multiplication effect had the power reflectivity coefficient more than 90% in the frequency band 10% for the H{sup 10} wave of the square waveguide with the maximum about 100% at a frequency 45GHz. The down-stream narrow-band Bragg reflector had the power reflection coefficient approximately 80% in the frequency band of 4% near 45GHz for the operating mode.

  13. Therapeutic targets and limits of minocycline neuroprotection in experimental ischemic stroke

    Directory of Open Access Journals (Sweden)

    Kaneko Yuji

    2009-10-01

    Full Text Available Abstract Background Minocycline, a second-generation tetracycline with anti-inflammatory and anti-apoptotic properties, has been shown to promote therapeutic benefits in experimental stroke. However, equally compelling evidence demonstrates that the drug exerts variable and even detrimental effects in many neurological disease models. Assessment of the mechanism underlying minocycline neuroprotection should clarify the drug's clinical value in acute stroke setting. Results Here, we demonstrate that minocycline attenuates both in vitro (oxygen glucose deprivation and in vivo (middle cerebral artery occlusion experimentally induced ischemic deficits by direct inhibition of apoptotic-like neuronal cell death involving the anti-apoptotic Bcl-2/cytochrome c pathway. Such anti-apoptotic effect of minocycline is seen in neurons, but not apparent in astrocytes. Our data further indicate that the neuroprotection is dose-dependent, in that only low dose minocycline inhibits neuronal cell death cascades at the acute stroke phase, whereas the high dose exacerbates the ischemic injury. Conclusion The present study advises our community to proceed with caution to use the minimally invasive intravenous delivery of low dose minocycline in order to afford neuroprotection that is safe for stroke.

  14. Experimental demonstration of information to energy conversion in a quantum system at the Landauer limit

    Science.gov (United States)

    Peterson, J. P. S.; Sarthour, R. S.; Souza, A. M.; Oliveira, I. S.; Goold, J.; Modi, K.; Soares-Pinto, D. O.; Céleri, L. C.

    2016-04-01

    Landauer's principle sets fundamental thermodynamical constraints for classical and quantum information processing, thus affecting not only various branches of physics, but also of computer science and engineering. Despite its importance, this principle was only recently experimentally considered for classical systems. Here we employ a nuclear magnetic resonance set-up to experimentally address the information to energy conversion in a quantum system. Specifically, we consider a three nuclear spins S =1/2 (qubits) molecule-the system, the reservoir and the ancilla-to measure the heat dissipated during the implementation of a global system-reservoir unitary interaction that changes the information content of the system. By employing an interferometric technique, we were able to reconstruct the heat distribution associated with the unitary interaction. Then, through quantum state tomography, we measured the relative change in the entropy of the system. In this way, we were able to verify that an operation that changes the information content of the system must necessarily generate heat in the reservoir, exactly as predicted by Landauer's principle. The scheme presented here allows for the detailed study of irreversible entropy production in quantum information processors.

  15. Low Resolution Limits and Inaccurate Algorithms Decrease Significantly the Value of Late Loss in Current Drug-Eluting Stent Trials

    Directory of Open Access Journals (Sweden)

    Johannes B. Dahm

    2012-01-01

    Full Text Available Quantitative coronary and vascular angiography (QCA resp., QVA remains the current gold standard for evaluation of restenosis. Late loss as one of the most commonly accepted parameters to highlight efficacy of the various devices has shown high correlation to clinical parameters but, surprisingly, has no impact on the evaluation of the remaining amount of restenostic tissue. The current clinical practice leads to unrealistic late loss calculations. Smaller late loss differences are usually not greater than the inherited resolution limits of QCA, which is especially the case in small differences between the various stents in the drug-eluting stent era. Late loss include additional systematic and random errors, due to the fact that measurements were taken at two different time points including the inherited resolution and calibration limits of QCA on two occasions. Due to the limited value of late loss in discriminating the small differences between the one and other DES, late lumen area loss and clearly defined calculation algorithms (e.g., MLD-relocation should be used in future DES studies also to fulfill the more stringent regulatory requirements.

  16. Application of a modified flux-coupling type superconducting fault current limiter to transient performance enhancement of micro-grid

    Science.gov (United States)

    Chen, Lei; Zheng, Feng; Deng, Changhong; Li, Shichun; Li, Miao; Liu, Hui; Zhu, Lin; Guo, Fang

    2015-11-01

    Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid's operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid's fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL's contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.

  17. State of the art of superconducting fault current limiters and their application to the electric power system

    Science.gov (United States)

    Morandi, Antonio

    2013-01-01

    Modern electric power systems are becoming more and more complex in order to meet new needs. Nowadays a high power quality is mandatory and there is the need to integrate increasing amounts of on-site generation. All this translates in more sophisticated electric network with intrinsically high short circuit rate. This network is vulnerable in case of fault and special protection apparatus and procedures needs to be developed in order to avoid costly or even irreversible damage. A superconducting fault current limiter (SFCL) is a device with a negligible impedance in normal operating conditions that reliably switches to a high impedance state in case of extra-current. Such a device is able to increase the short circuit power of an electric network and to contemporarily eliminate the hazard during the fault. It can be regarded as a key component for future electric power systems. In this paper the state of the art of superconducting fault current limiters mature for applications is briefly resumed and the potential impact of this device on the paradigm of design and operation of power systems is analyzed. In particular the use of the FCL as a mean to allow more interconnection of MV bus-bars as well an increased immunity with respect to the voltage disturbances induced by critical customer is discussed. The possibility to integrate more distributed generation in the distribution grid is also considered.

  18. 某型导弹舵机限流电路分析%Missile Servo Current-limiting Circuit Analysis

    Institute of Scientific and Technical Information of China (English)

    王小波; 付克亚

    2016-01-01

    The current of current-limiting circuit frequently surpasses its nomial value in testing servo control circuit of a certain type missile.This paper analyses the working principle of current-limiting circuit,identifies its main influence factors,and brings forward the corresponding solution to solve such failure and promote the passing ratio of control circuit assembly test.The feasibility and effectiveness of the solution method is validat-ed in practice.%某型导弹舵机控制电路在测试时,经常出现限幅电流超差故障。该文从分析限流电路工作原理出发,查找出其主要影响因素,并有针对性的提出解决方法,以解决此类故障,提高控制电路装配测试合格率。通过生产实际,验证了这些解决方法的可行性和有效性。

  19. Flammability limits in flowing ethene-air-nitrogen mixtures: an experimental study

    OpenAIRE

    Bolk, J.W.; Siccama, N.B.; Westerterp, K.R.

    1996-01-01

    A large pilot plant was constructed to study the upper flammability limit of ethene-air-nitrogen mixtures under conditions of flow. The gas mixtures flowed through an explosion tube with a length of 3.0 m and a diameter of 21 mm. An electrically heated wire was used as ignition source. Experiments were performed at pressures of 5 and 10 bar, with gas temperatures between 25 and 300 °C and with the wire fixed horizontally and vertically. Three different phenomena are observed: negligible react...

  20. 'I think it will eventually be done away with': Attitudes among healthcare professionals towards the current system of animal experimentation.

    Science.gov (United States)

    Dignon, Andrée

    2016-08-01

    This article describes a study of attitudes to the current system of animal experimentation (for the production of health interventions) among 52 UK healthcare professionals. These healthcare professionals participated in three separate focus groups (of 18, 17 and 17 participants) and were invited to respond to the question 'what is your opinion about the current system of animal testing?' The study focused specifically on their views of the current system (rather than their views of animal testing in general). The healthcare professionals were critical of the current system, particularly with regard to regulation, secrecy, validity, unnecessary suffering and welfare. © The Author(s) 2014.

  1. Limited Susceptibility of Cynomolgus Monkeys (Macaca fascicularis) to Leprosy after Experimental Administration of Mycobacterium leprae

    Science.gov (United States)

    Walsh, Gerald P.; Dela Cruz, Eduardo C.; Abalos, Rodolfo M.; Tan, Esterlina V.; Fajardo, Tranquilino T.; Villahermosa, Laarni G.; Cellona, Roland V.; Balagon, Maria V.; White, Valerie A.; Saunderson, Paul R.; Walsh, Douglas S.

    2012-01-01

    Cynomolgus monkeys are a useful model for human tuberculosis, but susceptibility to M. leprae is unknown. A cynomolgus model of leprosy could increase understanding of pathogenesis—importantly, neuritis and nerve-damaging reactions. We administered viable Mycobacterium leprae to 24 cynomolgus monkeys by three routes, with a median follow-up period of 6 years (range = 1–19 years) involving biopsies, nasal smears, antiphenolic glycolipid-1 (PGL-1) antibody serology, and lepromin skin testing. Most developed evanescent papules at intradermal M. leprae inoculation sites that, on biopsy, showed a robust cellular immune response akin to a lepromin skin test reaction; many produced PGL-1 antibodies. At necropsy, four monkeys, without cutaneous or gross neurological signs of leprosy but with elevated PGL-1 antibodies, including three with nasal smears (+) for acid fast bacilli (AFB), showed histological features, including AFB, suggestive of leprosy at several sites. Overall, however, cynomolgus monkeys seem minimally susceptible to leprosy after experimental M. leprae administration. PMID:22855766

  2. Experimental and numerical limits in parameter studies of a hydro-aeroelastic vibration phenomenon

    Science.gov (United States)

    Seidel, Christian

    2017-07-01

    Rain-wind induced vibrations are a hydro-aeroelastic vibration phenomenon that occurs when rain and wind act simultaneously on cables, hangars and ropes. The vibration phenomena may induce oscillations with large amplitudes, thus the fatigue of construction elements is possible. The paper presents a possible fluid-mechanical interpretation of rain-wind induced vibrations. Based on this interpretation a mechanical model is deduced, in order to enable numerical investigations. In order to account for the unsteady aerodynamics a hybrid method is used, which records the lift and drag coefficients as well as the distributions of pressure and shear stress from experiments in the wind tunnel. The complex system of nonlinear differential equations is analysed concerning the stability of solutions. As an example demonstrating the border zones between numerical and experimental investigations, a parameter study for the influence of the cylinder diameter on the onset wind velocity is shown.

  3. CFD studies on the phenomena around counter-current flow limitations of gas/liquid two-phase flow in a model of a PWR hot leg

    Energy Technology Data Exchange (ETDEWEB)

    Deendarlianto, E-mail: deendarlianto@ugm.ac.id [Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Safety Research, P.O. Box 510 119, D-01314 Dresden (Germany); Department of Mechanical and Industrial Engineering, Faculty of Engineering, Gadjah Mada University, Jalan Grafika No. 2, Yogyakarta 55281 (Indonesia); Hoehne, Thomas; Lucas, Dirk; Vallee, Christophe [Helmholtz-Zentrum Dresden-Rossendorf e.V., Institute of Safety Research, P.O. Box 510 119, D-01314 Dresden (Germany); Zabala, Gustavo Adolfo Montoya [Department of Chemical Engineering, Simon Bolivar University, Valle of Sartenejas, Caracas 1080 (Venezuela, Bolivarian Republic of)

    2011-12-15

    Highlights: Black-Right-Pointing-Pointer We modelled CCFL in a PWR hot leg using Algebraic Interfacial Area Density model. Black-Right-Pointing-Pointer The model is able to distinguish the local flow morphologies. Black-Right-Pointing-Pointer Test fluids are air-water and steam-water. Black-Right-Pointing-Pointer Calculated CCFL and water level are in good agreement with experimental data. - Abstract: In order to improve the understanding of counter-current two-phase flow and to validate new physical models, CFD simulations of a 1/3rd scale model of the hot leg of a German Konvoi pressurized water reactor (PWR) with rectangular cross section were performed. Selected counter-current flow limitation (CCFL) experiments conducted at Helmholtz-Zentrum Dresden-Rossendorf (HZDR) were calculated with ANSYS CFX using the multi-fluid Euler-Euler modelling approach. The transient calculations were carried out using a gas/liquid inhomogeneous multiphase flow model coupled with a shear stress transport (SST) turbulence model. In the simulation, the drag law was approached by a newly developed correlation of the drag coefficient in the Algebraic Interfacial Area Density (AIAD) model. The model can distinguish the bubbles, droplets and the free surface using the local liquid phase volume fraction value. A comparison with the high-speed video observations shows a good qualitative agreement. The results indicate also a quantitative agreement between calculations and experimental data for the CCFL characteristics and the water level inside the hot leg channel.

  4. The Heterogeneous Mineral Content of Bone—Using Stochastic Arguments and Simulations to Overcome Experimental Limitations

    Science.gov (United States)

    Lukas, C.; Kollmannsberger, P.; Ruffoni, D.; Roschger, P.; Fratzl, P.; Weinkamer, R.

    2011-07-01

    On a sub-millimeter length scale, bone is a very heterogeneous material with varying mineral content. This heterogeneity can be measured by quantitative backscattered electron imaging (qBEI) and quantified by a probability distribution called the bone mineralization density distribution (BMDD). The stochastic nature of the backscattering of electrons during the measurement makes the results dependent on the acquisition time. In this work the influence of the measurement conditions was quantified and was corrected for using Tikhonov regularization. Deconvolution reduces the width of the BMDD and allows a more precise definition of a reference BMDD for healthy adults. The corrected information was used as input for a mathematical model that predicts the time evolution of the BMDD. Simulations of osteoporosis treatment reveal a double peak in the BMDD that is not observed in experiments due to limited acquisition time. Our method allows determining the necessary acquisition time to resolve such double peaks.

  5. New experimental limits on non-Newtonian forces in the micrometer-range

    CERN Document Server

    Sushkov, A O; Dalvit, D A R; Lamoreaux, S K

    2011-01-01

    We report measurements of the short-range forces between two macroscopic gold-coated plates using a torsion pendulum. The force is measured for separations between 0.7 $\\mu$m and 7 $\\mu$m, and is well described by a combination of the Casimir force, including the finite-temperature correction, and an electrostatic force due to patch potentials on the plate surfaces. We use our data to place constraints on the Yukawa-type "new" forces predicted by theories with extra dimensions. We establish a new best bound for force ranges 0.4 $\\mu$m to 4 $\\mu$m, and, for forces mediated by gauge bosons propagating in $(4+n)$ dimensions and coupling to the baryon number, extract a $(4+n)$-dimensional Planck scale lower limit of $M_*>70$ TeV.

  6. Influences of Resistor-Type Superconducting Fault Current Limiter on Power System Transient Stability with Asymmetrical Short-Circuit Faults

    Institute of Scientific and Technical Information of China (English)

    Xue-Ping Gu; Zhi-Long Yang

    2008-01-01

    The transient stability of a single machine to infinite-busbar power system with resistor- type superconducting fault current limiters (SFCL) is analyzed under asymmetrical short-circuit fault conditions. The SFCL is considered to introduce a resistance into the three-phase circuits when faults occur. Based on the power-angle curves for different short-circuit conditions of the single-line to ground, double-line to ground and line to line short-circuit faults, the influences of the SFCLs on transient stability are analyzed in detail. The time-domain simulation of transient stability is carried out to verify the analytical results.

  7. Assessment of the impact of HTSCs on superconducting fault-current limiters. [High Temperature SuperConductors (HTSCs)

    Energy Technology Data Exchange (ETDEWEB)

    Giese, R.F. (Argonne National Lab., IL (United States)); Runde, M. (Energiforsyningens Forskningsinstitutt A/S, Trondheim (Norway))

    1993-01-01

    The possible impact of nitrogen-cooled superconductors on the desip and cost of superconducting fault-current limiters is assessed by considering the technical specifications such devices must meet and by comparing material properties of 77-K and 4-K superconductors. The main advantages of operating superconductors at 77 K are that the refrigeration operating cost is reduced by a factor of up to 25 and the refrigeration capital cost is reduced by a factor of up to 10. The heat capacity is several orders of magnitude Larger at 77 K and at 4 K. This phenomenon increases conductor stability against flux jumps but makes switching from the superconducting to the normal state slow and difficult. Therefore, a high critical current density, probably at least 10[sup 5] A/cm[sup 2], is required.

  8. Technical Note: Millimeter precision in ultrasound based patient positioning: Experimental quantification of inherent technical limitations

    Energy Technology Data Exchange (ETDEWEB)

    Ballhausen, Hendrik, E-mail: hendrik.ballhausen@med.uni-muenchen.de; Hieber, Sheila; Li, Minglun; Belka, Claus; Reiner, Michael [Department of Radiotherapy and Radiation Oncology, University Hospital of the Ludwig-Maximilians-University, Marchioninistraße 15, 81377 Munich (Germany)

    2014-08-15

    Purpose: To identify the relevant technical sources of error of a system based on three-dimensional ultrasound (3D US) for patient positioning in external beam radiotherapy. To quantify these sources of error in a controlled laboratory setting. To estimate the resulting end-to-end geometric precision of the intramodality protocol. Methods: Two identical free-hand 3D US systems at both the planning-CT and the treatment room were calibrated to the laboratory frame of reference. Every step of the calibration chain was repeated multiple times to estimate its contribution to overall systematic and random error. Optimal margins were computed given the identified and quantified systematic and random errors. Results: In descending order of magnitude, the identified and quantified sources of error were: alignment of calibration phantom to laser marks 0.78 mm, alignment of lasers in treatment vs planning room 0.51 mm, calibration and tracking of 3D US probe 0.49 mm, alignment of stereoscopic infrared camera to calibration phantom 0.03 mm. Under ideal laboratory conditions, these errors are expected to limit ultrasound-based positioning to an accuracy of 1.05 mm radially. Conclusions: The investigated 3D ultrasound system achieves an intramodal accuracy of about 1 mm radially in a controlled laboratory setting. The identified systematic and random errors require an optimal clinical tumor volume to planning target volume margin of about 3 mm. These inherent technical limitations do not prevent clinical use, including hypofractionation or stereotactic body radiation therapy.

  9. Two current experimental problems in heavy lepton physics: tau decay modes and close mass pairs

    Energy Technology Data Exchange (ETDEWEB)

    Perl, M.L.

    1987-08-01

    This paper investigates tau lepton decay modes and close-mass lepton pairs. The major part of the paper discusses branching functions from experimental and theoretical viewpoints. Finally, the lack of experimental signatures of close-mass lepton pairs are reviewed. 15 refs., 2 figs., 11 tabs. (JDH)

  10. DWPF COAL-CARBON WASTE ACCEPTANCE CRITERIA LIMIT EVALUATION BASED ON EXPERIMENTAL WORK (TANK 48 IMPACT STUDY)

    Energy Technology Data Exchange (ETDEWEB)

    Lambert, D.; Choi, A.

    2010-10-15

    This report summarizes the results of both experimental and modeling studies performed using Sludge Batch 10 (SB10) simulants and FBSR product from Tank 48 simulant testing in order to develop higher levels of coal-carbon that can be managed by DWPF. Once the Fluidized Bed Steam Reforming (FBSR) process starts up for treatment of Tank 48 legacy waste, the FBSR product stream will contribute higher levels of coal-carbon in the sludge batch for processing at DWPF. Coal-carbon is added into the FBSR process as a reductant and some of it will be present in the FBSR product as unreacted coal. The FBSR product will be slurried in water, transferred to Tank Farm and will be combined with sludge and washed to produce the sludge batch that DWPF will process. The FBSR product is high in both water soluble sodium carbonate and unreacted coal-carbon. Most of the sodium carbonate is removed during washing but all of the coal-carbon will remain and become part of the DWPF sludge batch. A paper study was performed earlier to assess the impact of FBSR coal-carbon on the DWPF Chemical Processing Cell (CPC) operation and melter off-gas flammability by combining it with SB10-SB13. The results of the paper study are documented in Ref. 7 and the key findings included that SB10 would be the most difficult batch to process with the FBSR coal present and up to 5,000 mg/kg of coal-carbon could be fed to the melter without exceeding the off-gas flammability safety basis limits. In the present study, a bench-scale demonstration of the DWPF CPC processing was performed using SB10 simulants spiked with varying amounts of coal, and the resulting seven CPC products were fed to the DWPF melter cold cap and off-gas dynamics models to determine the maximum coal that can be processed through the melter without exceeding the off-gas flammability safety basis limits. Based on the results of these experimental and modeling studies, the presence of coal-carbon in the sludge feed to DWPF is found to have

  11. Upper Extremity Injured Workers Stratified by Current Work Status: An Examination of Health Characteristics, Work Limitations and Work Instability

    Directory of Open Access Journals (Sweden)

    H Grant

    2010-06-01

    Full Text Available Background: Upper extremity injured workers are an under-studied population. A descriptive comparison of workers with shoulder, elbow and hand injuries reporting to a Canadian Workplace Safety and Insurance Board (WSIB clinic was undertaken.Objective: To determine if differences existed between injury groups stratified by current work status.Methods: All WSIB claimants reporting to our upper extremity clinic between 2003 and 2008 were approached to participate in this descriptive study. 314 working and 146 non-working WSIB claimants completed the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH; Short Form health survey (SF36; Worker’s Limitations Questionnaire and the Work Instability Scale. Various parametric and non-parametric analyses were used to assess significant differences between groups on demographic, work and health related variables.Results: Hand, followed by the shoulder and elbow were the most common site of injury. Most non-workers listed their current injury as the reason for being off work, and attempted to return to work once since their injury occurrence. Non-workers and a subset of workers at high risk for work loss showed significantly worse mental functioning. Workers identified physical demands as the most frequent injury-related on the job limitation. 60% of current workers were listed as low risk for work loss on the Work Instability Scale.Conclusions: Poorer mental functioning, being female and sustaining a shoulder injury were risk factors for work instability. Our cohort of injured non-workers were unable to return to work due to their current injury, reinforcing the need to advocate for modified duties, shorter hours and a work environment where stress and injury recurrence is reduced. Future studies examining pre-injury depression as a risk factor for prolonged work absences are warranted.

  12. Experimental study on the performance limitation of micro heat pipes of non circular cross-sections

    Directory of Open Access Journals (Sweden)

    Mahmood Lutful Sakib

    2008-01-01

    Full Text Available An experimental study of three different cross-sections (circular, semicircular and rectangular of micro heat pipes having same hydraulic diameter (D= 3mm is carried out at three different inclination angles (0°, 45°, 90° using water as the working fluid. Evaporator section of the pipe is heated by an electric heater and the condenser section is cooled by water circulation in an annular space between the condenser section and the water jacket. Temperatures at different locations of the pipe are measured using five calibrated K type thermocouples. Heat supply is varied using a voltage regulator which is measured by a precision ammeter and a voltmeter. It is found that thermal performance tends to deteriorate as the micro heat pipe is flattened. Thus among all cross-sections of the pipes circular cross-section exhibits the best thermal performance followed by semicircular and rectangular cross-sections. Moreover maximum heat transfer capability of the pipes also decreases with decreasing of its inclination angle. A correlation is developed using all the gathered data of the present study to predict the heat transfer coefficient of micro heat pipes of different cross-sections placed at different inclination angles.

  13. Behavior of a DC zero-flux current sensor; Magnetic field analysis and comparison with experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Campostrini, P.; Sonato, P. (Istituto Gas Ionizzati del CNR, Padova (IT))

    1991-09-01

    In this paper the magnetic section of the finite-element ANSYS code, and in particular its optimization feature has been used to predict the behaviour of a zero-flux current sensor, briefly described, which is intended to be used in a fusion experiment to measure pulsed currents up to 50 kA, over a bandwidth from DC to 10 k Hz. The computed results fit well with those coming from experimental tests performed on a prototype.

  14. Current meter data from moored current meter casts in the SW Pacific (limit-147 E to 140 W) as part of the Equatorial Pacific Ocean Climate Studies (EPOCS) project from 29 September 1985 to 01 April 1986 (NODC Accession 8800136)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current meter data were collected using moored current meter casts in the SW Pacific (limit-147 E to 140 W) from September 29, 1985 to June 1, 1986. Data were...

  15. Current meter data from moored current meter casts in the Northwest Atlantic Ocean (limit-40 W) as part of the Outer Continental Shelf - Georges Bank (OCS -Georges Bank) project from 27 October 1980 - 01 November 1982 (NODC Accession 8600087)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current meter data were collected using moored current meter casts in the Northwest Atlantic Ocean (limit-40 W) from November 27, 1980 to November 1, 1982. Data were...

  16. Current meter data from moored current meter casts in the Northwest Atlantic Ocean (limit -40 W) as part of the Ocean Dumping project, 24 May 1990 - 17 June 1991 (NODC Accession 9300112)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current meter data were collected using moored current meter casts in the Northwest Atlantic Ocean (limit -40 W) from May 24, 1990 to June 17, 1991. Data were...

  17. Temperature and current profiles from BT and current profilers from DRIFTING PLATFORMS from the SW Atlantic (limit-20 W) and other locations from 01 January 1993 to 31 December 1995 (NODC Accession 9600085)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Temperature and current data from BT cast and current profilers from DRIFTING PLATFORMS from the SW Atlantic (limit-20 W) and other locations. Data was collected by...

  18. Current components, physical, and other data from moored current meters and CTD casts from NOAA Ship Discoverer and other platforms from the NE Pacific (limit-180) from 1993-08-18 to 1994-09-28 (NODC Accession 9500006)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current components, physical, and other data from moored current meters and CTD casts from NOAA Ship DISCOVERER and other platforms from the NE Pacific (limit-180)....

  19. Current meter data from moored current meter casts in the Northwest Atlantic Ocean (limit-40 W) as part of the Outer Continental Shelf - Georges Bank (OCS -Georges Bank) project from 25 October 1980 - 01 November 1982 (NODC Accession 8600046)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current meter data were collected using moored current meter casts in the Northwest Atlantic Ocean (limit-40 W) from October 25, 1980 to November 1, 1982. Data were...

  20. Current components, physical, and other data from moored current meters and CTD casts from NOAA Ship Discoverer and other platforms from the NE Pacific (limit-180) from 1994-04-22 to 1995-08-20 (NODC Accession 9500150)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current components, physical, and other data from moored current meters and CTD casts from NOAA Ship DISCOVERER and other platforms from the NE Pacific (limit-180)....

  1. Pirfenidone restricts Th2 differentiation in vitro and limits Th2 response in experimental liver fibrosis.

    Science.gov (United States)

    Navarro-Partida, Jose; Martinez-Rizo, Abril Bernardette; Gonzalez-Cuevas, Jaime; Arrevillaga-Boni, Gerardo; Ortiz-Navarrete, Vianney; Armendariz-Borunda, Juan

    2012-03-05

    Polarized T helper type 2 (Th2) response is linked with fibrosis. Here, we evaluated the effect of the anti-fibrotic agent pirfenidone on Th type 1 (Th1) and Th2 responses. For in vivo testing; Wistar rats were made cirrhotic by intraperitoneal administration of thioacetamide. Once hepatic damage was established, pirfenidone was administered intragastrically on a daily basis during three weeks. Gene expression of Th marks was evaluated by RT-PCR and Western blot assays from liver homogenates. Pirfenidone therapy induced down-regulation of Th2 transcripts and proteins (GATA3 and IL-4), without affecting significantly Th1 genes expression (T-bet and IFN-γ). We found that the activated form of p38 MAPK (identified by Western blot) was reduced by pirfenidone treatment, which is consistent with the anti-Th2 activity observed. Pirfenidone reduced GATA3 nuclear localization without modifying its DNA binding activity (evaluated by electrophoretic mobility shift assay). For in vitro testing; human naive CD4+ T cells were cultured in either Th1 or Th2 polarizing conditions in the presence of pirfenidone and flow cytometric analysis of intracellular synthesis of IFN-γ and IL-4 was conducted. Pirfenidone impaired development of Th2 subpopulation. In conclusion, pirfenidone is capable of impairing Th2 differentiation and limits Th2 profibrogenic response. The mechanism involves p38 inhibition and regulation of GATA3 expression and translocation.

  2. History, ethics, advantages and limitations of experimental models for hepatic ablation.

    Science.gov (United States)

    Ong, Seok Ling; Gravante, Gianpiero; Metcalfe, Matthew S; Dennison, Ashley R

    2013-01-14

    Numerous techniques developed in medicine require careful evaluation to determine their indications, limitations and potential side effects prior to their clinical use. At present this generally involves the use of animal models which is undesirable from an ethical standpoint, requires complex and time-consuming authorization, and is very expensive. This process is exemplified in the development of hepatic ablation techniques, starting experiments on explanted livers and progressing to safety and efficacy studies in living animals prior to clinical studies. The two main approaches used are ex vivo isolated non-perfused liver models and in vivo animal models. Ex vivo non perfused models are less expensive, easier to obtain but not suitable to study the heat sink effect or experiments requiring several hours. In vivo animal models closely resemble clinical subjects but often are expensive and have small sample sizes due to ethical guidelines. Isolated perfused ex vivo liver models have been used to study drug toxicity, liver failure, organ transplantation and hepatic ablation and combine advantages of both previous models.

  3. A Fatigue Crack Size Evaluation Method Based on Lamb Wave Simulation and Limited Experimental Data

    Directory of Open Access Journals (Sweden)

    Jingjing He

    2017-09-01

    Full Text Available This paper presents a systematic and general method for Lamb wave-based crack size quantification using finite element simulations and Bayesian updating. The method consists of construction of a baseline quantification model using finite element simulation data and Bayesian updating with limited Lamb wave data from target structure. The baseline model correlates two proposed damage sensitive features, namely the normalized amplitude and phase change, with the crack length through a response surface model. The two damage sensitive features are extracted from the first received S0 mode wave package. The model parameters of the baseline model are estimated using finite element simulation data. To account for uncertainties from numerical modeling, geometry, material and manufacturing between the baseline model and the target model, Bayesian method is employed to update the baseline model with a few measurements acquired from the actual target structure. A rigorous validation is made using in-situ fatigue testing and Lamb wave data from coupon specimens and realistic lap-joint components. The effectiveness and accuracy of the proposed method is demonstrated under different loading and damage conditions.

  4. Fault Current Limitation and Analysis of Current Limiting Characteristic for Multi-terminal VSC-HVDC DC Lines%多端VSC-HVDC直流线路故障限流及限流特性分析

    Institute of Scientific and Technical Information of China (English)

    刘剑; 邰能灵; 范春菊; 郑晓冬; 唐跃中

    2016-01-01

    基于电压源型换流器(voltage source converters,VSC)的多端柔性直流系统中直流线路的故障电流上升速度快、电流峰值大。然而具有大容量、快切断能力的高压直流断路器正在研制中。结合目前直流断路器开断容量水平,该文提出通过在直流线路两端串入限流电路的方法来限制故障电流的峰值和电流的上升速度率,并给出相关参数的理论计算方法。对该电路的限流特性进行分析与对比,结果表明,该限流电路能有效抑制故障电流,降低了对直流断路器开断容量和开断速度的要求。在该限流电路的基础上,提出一种多端VSC-HVDC 直流线路故障处理方案。仿真分析表明,该故障处理方案能够有效抑制直流线路故障电流以及 IGBT 并联二极管电流,故障切除后非故障系统能保持正常运行,可以有效地增强多端VSC-HVDC系统对直流线路故障的处理能力。%The fault current of DC line in multi-terminal HVDC system based on voltage source converters (VSC) increases quickly with large peak, while the DC circuit breaker with large capacity and fast breaking speed is still under development. Combined with the capacity level of DC circuit breaker breaking, a current limiting circuit was proposed to limit the peak and rising rate of fault current by connecting it to DC line ends. Theoretical calculation method for the circuit parameters was also given. The analysis results about the circuit and the comparison with other methods show that the proposed circuit is able to limit the fault current effectively and reduce the requirement for DC breaker capacity and speed. Based on the circuit, a fault-handling scheme for DC lines in multi-terminal VSC-HVDC was proposed. The simulation results show that the proposed scheme is capable of limiting fault current of DC lines and parallel diodes effectively, and non-fault system can maintain normal operation after fault

  5. Optimal allocation of fault current limiters for sustaining overcurrent relays coordination in a power system with distributed generation

    Directory of Open Access Journals (Sweden)

    A. Elmitwally

    2015-12-01

    Full Text Available This paper addresses the problem of overcurrent relays (OCRs coordination in the presence of DGs. OCRs are optimally set to work in a coordinated manner to isolate faults with minimal impacts on customers. The penetration of DGs into the power system changes the fault current levels seen by the OCRs. This can deteriorate the coordinated operation of OCRs. Operation time difference between backup and main relays can be below the standard limit or even the backup OCR can incorrectly work before the main OCR. Though resetting of OCRs is tedious especially in large systems, it cannot alone restore the original coordinated operation in the presence of DGs. The paper investigates the optimal utilization of fault current limiters (FCLs to maintain the directional OCRs coordinated operation without any need to OCRs resetting irrespective of DGs status. It is required to maintain the OCRs coordination at minimum cost of prospective FCLs. Hence, the FCLs location and sizing problem is formulated as a constrained multi-objective optimization problem. Multi-objective particle swarm optimization is adopted for solving the optimization problem to determine the optimal locations and sizes of FCLs. The proposed algorithm is applied to meshed and radial power systems at different DGs arrangements using different types of FCLs. Moreover, the OCRs coordination problem is studied when the system includes both directional and non-directional OCRs. Comparative analysis of results is provided.

  6. 饱和铁心型超导限流器%Saturated iron - core superconducting fault current limiter

    Institute of Scientific and Technical Information of China (English)

    庞骁刚; 龚伟志; 洪辉; 任安林; 信赢

    2012-01-01

    饱和铁心型超导限流器具有限流功能可靠、输电稳态损耗小、限流恢复时间短等优异特性.根据其工作原理,一方面,用于直流励磁的超导绕组自身不承受短路电流冲击,这避免了其它类型超导限流器中由于超导绕组失超所带来的诸多技术难题;另一方面,其主体电抗器可以借鉴成熟的铁心电抗器技术.因此,饱和铁心型超导限流器的以其优异的性能特性和成熟的工程实现技术,成为迄今为止人们研究的各类超导限流器中的最具实用价值的一种.在电网容量不断扩大,智能化水平不断提高的今天,饱和铁心型超导限流器有非常广阔的应用前景.文中将叙述饱和铁心型超导限流器的基本原理、结构形式、功能特性,并对已在云南普吉变电站挂网运行的35kV/90MVA超导限流器进行简要介绍.%Saturated iron -core superconducting fault current limiters have some superior performance features, such as very low operation loss at normal power transmission, high impedance at fault current limiting, immediately reacting, and fast recovering. Thinks to its working mechanism, there is no risk of quench to the superconductor coil on the impact of the fault current, so complex mechanical, electrical and thermal protection measures can be avoided. The complicity to deal with a quench of superconductor might be a severe technical barrier for other types of superconducting fault current limiiers. In addition, the reactor of the device is mainly composed by iron cores and copper coils, which can be built with the technology for conventional transformers or reactors. For these reasons, this kind of superconducting fault current limiters is considered the most practically viable device in industrial applications. In this paper, the fundamental principles, the structures and the performance features of saturated iron core SFCLs are introduced. The specifications, testing results, and the operational

  7. Study of counter current flow limitation model of MARS-KS and SPACE codes under Dukler's air/water flooding test conditions

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Won Woong; Kim, Min Gil; Lee, Jeong Ik [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of); Bang, Young Seok [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2015-10-15

    In particular, CCFL(the counter current flow limitation) occurs in components such as hot leg, downcomer annulus and steam generator inlet plenum during LOCA which is possible to have flows in two opposite directions. Therefore, CCFL is one of the thermal-hydraulic models which has significant effect on the reactor safety analysis code performance. In this study, the CCFL model will be evaluated with MARS-KS based on two-phase two-field governing equations and SPACE code based on two-phase three-field governing equations. This study will be conducted by comparing MARS-KS code which is being used for evaluating the safety of a Korean Nuclear Power Plant and SPACE code which is currently under assessment for evaluating the safety of the designed nuclear power plant. In this study, comparison of the results of liquid upflow and liquid downflow rate for different gas flow rate from two code to the famous Dukler's CCFL experimental data are presented. This study will be helpful to understand the difference between system analysis codes with different governing equations, models and correlations, and further improving the accuracy of system analysis codes. In the nuclear reactor system, CCFL is an important phenomenon for evaluating the safety of nuclear reactors. This is because CCFL phenomenon can limit injection of ECCS water when CCFL occurs in components such as hot leg, downcomer annulus or steam generator inlet plenum during LOCA which is possible to flow in two opposite directions. Therefore, CCFL is one of the thermal-hydraulic models which has significant effect on the reactor safety analysis code performance. In this study, the CCFL model was evaluated with MARS-KS and SPACE codes for studying the difference between system analysis codes with different governing equations, models and correlations. This study was conducted by comparing MARS-KS and SPACE code results of liquid upflow and liquid downflow rate for different gas flow rate to the famous Dukler

  8. Application of a modified flux-coupling type superconducting fault current limiter to transient performance enhancement of micro-grid

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Lei, E-mail: stclchen1982@163.com [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zheng, Feng; Deng, Changhong; Li, Shichun; Li, Miao; Liu, Hui [School of Electrical Engineering, Wuhan University, Wuhan 430072 (China); Zhu, Lin [Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville 37996 (United States); Guo, Fang [Department of Substation, Guang Dong Electric Power Design Institute, Guangzhou 510663 (China)

    2015-11-15

    Highlights: • A modified flux-coupling type SFCL is suggested to enhance the transient performance of a micro-grid. • The SFCL’s main contribution is to improve the micro-grid’s fault ride-through capability. • The SFCL also can make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. • The simulations show that the SFCL can availably strengthen the micro-grid’s voltage and frequency stability. - Abstract: Concerning the application and development of a micro-grid system which is designed to accommodate high penetration of intermittent renewable resources, one of the main issues is related to an increase in the fault-current level. It is crucial to ensure the micro-grid’s operational stability and service reliability when a fault occurs in the main network. In this paper, our research group suggests a modified flux-coupling type superconducting fault current limiter (SFCL) to enhance the transient performance of a typical micro-grid system. The SFCL is installed at the point of common coupling (PCC) between the main network and the micro-grid, and it is expected to actively improve the micro-grid’s fault ride-through capability. And for some specific faults, the micro-grid should disconnect from the main network, and the SFCL’s contribution is to make the micro-grid carry out a smooth transition between its grid-connected and islanded modes. Related theory derivation, technical discussion and simulation analysis are performed. From the demonstrated results, applying the SFCL can effectively limit the fault current, maintain the power balance, and enhance the voltage and frequency stability of the micro-grid.

  9. Limited acclimation in leaf anatomy to experimental drought in tropical rainforest trees.

    Science.gov (United States)

    Binks, Oliver; Meir, Patrick; Rowland, Lucy; da Costa, Antonio Carlos Lola; Vasconcelos, Steel Silva; de Oliveira, Alex Antonio Ribeiro; Ferreira, Leandro; Mencuccini, Maurizio

    2016-12-01

    Dry periods are predicted to become more frequent and severe in the future in some parts of the tropics, including Amazonia, potentially causing reduced productivity, higher tree mortality and increased emissions of stored carbon. Using a long-term (12 year) through-fall exclusion (TFE) experiment in the tropics, we test the hypothesis that trees produce leaves adapted to cope with higher levels of water stress, by examining the following leaf characteristics: area, thickness, leaf mass per area, vein density, stomatal density, the thickness of palisade mesophyll, spongy mesophyll and both of the epidermal layers, internal cavity volume and the average cell sizes of the palisade and spongy mesophyll. We also test whether differences in leaf anatomy are consistent with observed differential drought-induced mortality responses among taxa, and look for relationships between leaf anatomy, and leaf water relations and gas exchange parameters. Our data show that trees do not produce leaves that are more xeromorphic in response to 12 years of soil moisture deficit. However, the drought treatment did result in increases in the thickness of the adaxial epidermis (TFE: 20.5 ± 1.5 µm, control: 16.7 ± 1.0 µm) and the internal cavity volume (TFE: 2.43 ± 0.50 mm(3) cm(-2), control: 1.77 ± 0.30 mm(3) cm(-2)). No consistent differences were detected between drought-resistant and drought-sensitive taxa, although interactions occurred between drought-sensitivity status and drought treatment for the palisade mesophyll thickness (P = 0.034) and the cavity volume of the leaves (P = 0.025). The limited response to water deficit probably reflects a tight co-ordination between leaf morphology, water relations and photosynthetic properties. This suggests that there is little plasticity in these aspects of plant anatomy in these taxa, and that phenotypic plasticity in leaf traits may not facilitate the acclimation of Amazonian trees to the predicted future reductions in

  10. Faculty perceptions of the strengths, weaknesses and future prospects of the current medical undergraduate experimental physiology curriculum in Gujarat, India.

    Science.gov (United States)

    Paralikar, Swapnil; Shah, Chinmay

    2015-01-01

    Over the past several years, an opinion has emerged in India that the current practical curricula in medical schools fail to meet many of the objectives for which they were instituted. Hence, this study has assessed the perception of physiology faculty members regarding the current experimental physiology curriculum in one Indian state, Gujarat. The faculty were of the opinion that many of the topics currently taught in experimental physiology (amphibian nerve-muscle and heart muscle experiments) were outdated and clinically irrelevant: Therefore, the faculty advocated that duration of teaching time devoted to some of these topics should be reduced and topics with clinical relevance should be introduced at the undergraduate level. The faculty also felt that more emphasis should be laid on highlighting the clinical aspect related to each concept taught in experimental physiology . Moreover, a majority of faculty members were in favour of replacing the current practice in Gujarat of teaching experimental physiology only by explanation of graphs obtained from experiments conducted in the previous years, with computer assisted learning in small groups.

  11. Implementation of an Effective Fault Current Limiter for 1.5 MW DFIG in Wind Power Systems

    Directory of Open Access Journals (Sweden)

    M. Panneerselvam

    2014-05-01

    Full Text Available With the continuous increase of power demand, the capacities of renewable energy generation systems are being expanded. With the increased penetration of wind energy as a renewable energy source, there is a need to keep wind turbines connected to the grid during grid faults. The ability of WTGS (Wind Turbine Generation System to remain connected to the grid during faults is termed as Fault-Ride Through capability (FRT of the system. In this paper, the use of superconducting fault current limiter (SFCL is proposed to improve the FRT capability of WTGS thus improving reliability of the system. A Doubly-Fed Induction Generator (DFIG is considered as a wind-turbine generator for analysis. Detailed simulation results are obtained with and without SFCL considering the stator and rotor currents. Also, the voltage profile, real and reactive power magnitudes are analyzed. The computed results ensure that SFCL is effective in mitigating the fault current magnitude which would enhance the reliability and stability of the system as a whole.

  12. Zonal and Meridional Ocean Currents at TOPEX/Poseidon and JASON-1 Crossovers around Taiwan: Error Analysis and Limitation

    Directory of Open Access Journals (Sweden)

    Cheinway Hwang

    2008-01-01

    Full Text Available A crossover method for determining zonal and meridional ocean current components is examined using data at three crossovers of TOPEX/Poseidon and JASON-1 ground tracks over 2002 - 2006. To implement this method, a geoid model around Taiwan is constructed using surface and airborne gravity data. The modeled and observed geoidal heights at coastal benchmarks are consistent to 5 cm RMS with the means removed. The error and limitation of this method are discussed, concluding that, in order to obtain current velocities at a 10 cm s-1 accuracy and a 6-km resolution, the dynamic ocean topography (DOT at a mm-level accuracy is needed, which is not possible to achieve today. By filtering DOT to a spatial scale of 100 km or coarser, a 10 cm s-1 accuracy of velocity may be obtained. One crossover (A is situated south of Taiwan and near the Kuroshio, the second (B is at the axis of the Kuroshio and the third is located in the northern Taiwan Strait. These three crossovers feature different ocean current patterns. At a spatial scale of 120 km, the agreement among the altimeter, the Princeton Ocean Model (POM, and the drifter-derived velocities is the best at B, followed by that at A, and then C. In fact, at C the altimeter-derived velocities contradict the POM-derived values, and the tide model error is to be blamed. Further improvement on geoid modeling is suggested.

  13. Theoretical and Experimental Study of the Primary Current Distribution in Parallel-Plate Electrochemical Reactors

    Science.gov (United States)

    Vazquez Aranda, Armando I.; Henquin, Eduardo R.; Torres, Israel Rodriguez; Bisang, Jose M.

    2012-01-01

    A laboratory experiment is described to determine the primary current distribution in parallel-plate electrochemical reactors. The electrolyte is simulated by conductive paper and the electrodes are segmented to measure the current distribution. Experiments are reported with the electrolyte confined to the interelectrode gap, where the current…

  14. Experimental Phenomena of Improved Ohmic Confinement Induced by Modulated Toroidal Current on the HT-7 Tokamak

    Institute of Scientific and Technical Information of China (English)

    毛剑珊; 罗家融; P.Phillips; 赵君煜; 揭银先; 吴振伟; 胡立群; 李建刚

    2002-01-01

    The phenomena of improved ohmic confinement have been observed during the modulation of the toroidal curranton the Hefei superconducting Tokamak-7 (HT-7). In the experiment, the programming ohmic heating field wasmodulated. A toroidal frequency-modulated current induced by modulated loop voltage was added on the plasmaequilibrium current. The ratio of ac amplitude of the plasma current to the main plasma current is about 12-30%.These improved plasma confinement phenomena include the facts that the average electron density and the centralelectron temperature both increase, the Dα radiation from the edge is reduced, the magnetohydrodynamics isobviously suppressed by oscillating plasma current, eand the global energy confinement time increases by 27-45%o.It is found that the faster the modulation is, the more effective the improved ohmic confinement phase.

  15. Experimental study on directional solidification of Al-Si alloys under the influence of electric currents

    Science.gov (United States)

    Räbiger, D.; Zhang, Y.; Galindo, V.; Franke, S.; Willers, B.; Eckert, S.

    2016-07-01

    The application of electric currents during solidification can cause grain refinement in metallic alloys. However, the knowledge about the mechanisms underlying the decrease in grain size remains fragmentary. This study considers the solidification of Al-Si alloys under the influence of electric currents for the configuration of two parallel electrodes at the free surface. Solidification experiments were performed under the influence of both direct currents (DC) and rectangular electric current pulses (ECP). The interaction between the applied current and its own induced magnetic field causes a Lorentz force which produces an electro-vortex flow. Numerical simulations were conducted to calculate the Lorentz force, the Joule heating and the induced melt flow. The numerical predictions were confirmed by isothermal flow measurements in eutectic GaInSn. The results demonstrate that the grain refining effect observed in our experiments can be ascribed solely to the forced melt flow driven by the Lorentz force.

  16. Assaying embryotoxicity in the test tube: current limitations of the embryonic stem cell test (EST) challenging its applicability domain.

    Science.gov (United States)

    Riebeling, Christian; Hayess, Katrin; Peters, Annelieke K; Steemans, Margino; Spielmann, Horst; Luch, Andreas; Seiler, Andrea E M

    2012-05-01

    Testing for embryotoxicity in vitro is an attractive alternative to animal experimentation. The embryonic stem cell test (EST) is such a method, and it has been formally validated by the European Centre for the Validation of Alternative Methods. A number of recent studies have underscored the potential of this method. However, the EST performed well below the 78% accuracy expected from the validation study using a new set of chemicals and pharmaceutical compounds, and also of toxicity criteria, tested to enlarge the database of the validated EST as part of the Work Package III of the ReProTect Project funded within the 6th Framework Programme of the European Union. To assess the performance and applicability domain of the EST we present a detailed review of the substances and their effects in the EST being nitrofen, ochratoxin A, D-penicillamine, methylazoxymethanol, lovastatin, papaverine, warfarin, β-aminopropionitrile, dinoseb, furosemide, doxylamine, pravastatin, and metoclopramide. By delineation of the molecular mechanisms of the substances we identify six categories of reasons for misclassifications. Some of these limitations might also affect other in vitro methods assessing embryotoxicity. Substances that fall into these categories need to be included in future validation sets and in validation guidelines for embryotoxicity testing. Most importantly, we suggest conceivable improvements and additions to the EST which will resolve most of the limitations.

  17. Gardening in the zone of death: an experimental assessment of the absolute elevation limit of vascular plants

    Science.gov (United States)

    Dvorský, Miroslav; Chlumská, Zuzana; Altman, Jan; Čapková, Kateřina; Řeháková, Klára; Macek, Martin; Kopecký, Martin; Liancourt, Pierre; Doležal, Jiří

    2016-04-01

    Vascular plants in the western Tibetan Plateau reach 6000 m-the highest elevation on Earth. Due to the significant warming of the region, plant ranges are expected to shift upwards. However, factors governing maximum elevational limits of plant are unclear. To experimentally assess these factors, we transplanted 12 species from 5750 m to 5900 m (upper edge of vegetation) and 6100 m (beyond range) and monitored their survival for six years. In the first three years (2009–2012), there were plants surviving beyond the regional upper limit of vegetation. This supports the hypothesis of dispersal and/or recruitment limitation. Substantial warming, recorded in-situ during this period, very likely facilitated the survival. The survival was ecologically a non-random process, species better adapted to repeated soil freezing and thawing survived significantly better. No species have survived at 6100 m since 2013, probably due to the extreme snowfall in 2013. In conclusion, apart from the minimum heat requirements, our results show that episodic climatic events are decisive determinants of upper elevational limits of vascular plants.

  18. Experimentally determined mechanical properties of, and models for, the periodontal ligament: critical review of current literature.

    Science.gov (United States)

    Fill, Ted S; Carey, Jason P; Toogood, Roger W; Major, Paul W

    2011-01-01

    Introduction. This review is intended to highlight and discuss discrepancies in the literature of the periodontal ligament's (PDL) mechanical properties and the various experimental approaches used to measure them. Methods. Searches were performed on biomechanical and orthodontic publications (in databases: Compendex, EMBASE, MEDLINE, PubMed, ScienceDirect, and Scopus). Results. The review revealed that significant variations exist, some on the order of six orders of magnitude, in the PDL's elastic constants and mechanical properties. Possible explanations may be attributable to different experimental approaches and assumptions. Conclusions. The discrepancies highlight the need for further research into PDL properties under various clinical and experimental loading conditions. Better understanding of the PDL's biomechanical behavior under physiologic and traumatic loading conditions might enhance the understanding of the PDL's biologic reaction in health and disease. Providing a greater insight into the response of the PDL would be instrumental to orthodontists and engineers for designing more predictable, and therefore more efficacious, orthodontic appliances.

  19. Experimental evaluation of IGBT junction temperature measurement via peak gate current

    DEFF Research Database (Denmark)

    Baker, Nick; Munk-Nielsen, Stig; Iannuzzo, Francesco

    2015-01-01

    Temperature sensitive electrical parameters allow junction temperature measurements on power semiconductors without modification to module packaging. The peak gate current has recently been proposed for IGBT junction temperature measurement and relies on the temperature dependent resistance of th...

  20. Currents, HF Radio-derived, Monterey Bay, 25 hr, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  1. Currents, HF Radio-derived, Ano Nuevo, Normal Model, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements, with missing values filled in by a normal...

  2. Currents, HF Radio-derived, SF Bay Outlet, 25 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  3. Currents, HF Radio-derived, SF Bay, 33 hr, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 33 hour running average of the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  4. Currents, HF Radio-derived, Bodega Bay, 25 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  5. Currents, HF Radio-derived, Ano Nuevo, 25 hr, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  6. Currents, HF Radio-derived, Ano Nuevo, Normal Model, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements, with missing values filled in by a normal model....

  7. Currents, HF Radio-derived, Ano Nuevo, 25 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  8. Currents, HF Radio-derived, SF Bay Outlet, Normal Model, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements, with missing values filled in by a normal model....

  9. Currents, HF Radio-derived, Monterey Bay, Normal Model, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements, with missing values filled in by a normal model....

  10. Currents, HF Radio-derived, Monterey Bay, Normal Model, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements, with missing values filled in by a normal...

  11. Currents, HF Radio-derived, SF Bay Outlet, 25 hr, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  12. Currents, HF Radio-derived, Bodega Bay, 25 hr, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  13. Currents, HF Radio-derived, Monterey Bay, 25 hr, Zonal, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the 25 hour running average of the zonal component of ocean surface currents derived from High Frequency Radio-derived measurements. THIS IS AN...

  14. Currents, HF Radio-derived, SF Bay Outlet, Normal Model, Meridional, EXPERIMENTAL

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The data is the meridional component of ocean surface currents derived from High Frequency Radio-derived measurements, with missing values filled in by a normal...

  15. Estimation of electron mobility of n-doped 4, 7-diphenyl-1, 10-phenanthroline using space-charge-limited currents

    Institute of Scientific and Technical Information of China (English)

    Khizar-ul-Haq; Khan M A; Jiang Xueyin; Zhang Zhilin; Zhang Xiaowen; Zhang Liang; Li Jun

    2009-01-01

    The electron mobilities of 4, 7-diphenyl-1, 10-phenanthroline (BPhen) doped 8-hydroxyquinolinatolithium (Liq) at various thicknesses (50-300 nm) have been estimated by using space-charge-limited current measurements. It is observed that the electron mobility of 33 wt% Liq doped BPhen approaches its true value when the thickness is more than 200 nm. The electron mobility of 33 wt% Liq doped BPhen at 300 nm is found to be ~5.2 × 10~(-3) cm~2/(V·s) (at 0.3 MV/cm) with weak dependence on electric field, which is about one order of magnitude higher than that of pristine BPhen (3.4 × 10~(-4) cm~2/(V·s)) measured by SCLC. For the typical thickness of organic light-emitting devices, the electron mobility of doped BPhen is also investigated.

  16. Single-Case Experimental Designs: A Systematic Review of Published Research and Current Standards

    Science.gov (United States)

    Smith, Justin D.

    2012-01-01

    This article systematically reviews the research design and methodological characteristics of single-case experimental design (SCED) research published in peer-reviewed journals between 2000 and 2010. SCEDs provide researchers with a flexible and viable alternative to group designs with large sample sizes. However, methodological challenges have…

  17. Experimental analysis and theoretical predictions of the limit strains of a hot-dip galvanized interstitial-free steel sheet

    Directory of Open Access Journals (Sweden)

    Maria Carolina dos Santos Freitas

    2013-04-01

    Full Text Available In this work, the formability of a hot-dip galvanized interstitial-free (IF steel sheet was evaluated by means of uniaxial tensile and Forming Limit Curve (FLC tests. The FLC was defined using the flat-bottomed Marciniak's punch technique, where the strain analysis was made using a digital image correlation software. A plastic localization model was also proposed wherein the governing equations are solved with the help of the Newton's method. The investigated hot-dip galvanized IF steel sheet presented a very good formability level in the deep-drawing range consistent with the measured Lankford values. The predicted limit strains were found to be in good agreement with the experimental data of the hot-dip galvanized IF steel sheet owing to the definition of the localization model geometrical imperfection as a function of the experimental surface roughness evolution and, in particular, to the yield surface flattening near to the plane-strain stress state authorized by the adopted yield criterion.

  18. Opportunities to overcome the current limitations and challenges for efficient microbial production of optically pure lactic acid.

    Science.gov (United States)

    Abdel-Rahman, Mohamed Ali; Sonomoto, Kenji

    2016-10-20

    There has been growing interest in the microbial production of optically pure lactic acid due to the increased demand for lactic acid-derived environmentally friendly products, for example biodegradable plastic (poly-lactic acid), as an alternative to petroleum-derived materials. To maximize the market uptake of these products, their cost should be competitive and this could be achieved by decreasing the production cost of the raw material, that is, lactic acid. It is of great importance to isolate and develop robust and highly efficient microbial lactic acid producers. Alongside the fermentative substrate and concentration, the yield and productivity of lactic acid are key parameters and major factors in determining the final production cost of lactic acid. In this review, we will discuss the current limitations and challenges for cost-efficient microbial production of optically pure lactic acid. The main obstacles to effective fermentation are the use of food resources, indirect utilization of polymeric sugars, sensitivity to inhibitory compounds released during biomass treatments, substrate inhibition, decreased lactic acid yield and productivity, inefficient utilization of mixed sugars, end product inhibition, increased use of neutralizing agents, contamination problems, and decreased optical purity of lactic acid. Furthermore, opportunities to address and overcome these limitations, either by fermentation technology or metabolic engineering approaches, will be introduced and discussed.

  19. Use of cone beam computed tomography in implant dentistry: current concepts, indications and limitations for clinical practice and research.

    Science.gov (United States)

    Bornstein, Michael M; Horner, Keith; Jacobs, Reinhilde

    2017-02-01

    Diagnostic radiology is an essential component of treatment planning in the field of implant dentistry. This narrative review will present current concepts for the use of cone beam computed tomography imaging, before and after implant placement, in daily clinical practice and research. Guidelines for the selection of three-dimensional imaging will be discussed, and limitations will be highlighted. Current concepts of radiation dose optimization, including novel imaging modalities using low-dose protocols, will be presented. For preoperative cross-sectional imaging, data are still not available which demonstrate that cone beam computed tomography results in fewer intraoperative complications such as nerve damage or bleeding incidents, or that implants inserted using preoperative cone beam computed tomography data sets for planning purposes will exhibit higher survival or success rates. The use of cone beam computed tomography following the insertion of dental implants should be restricted to specific postoperative complications, such as damage of neurovascular structures or postoperative infections in relation to the maxillary sinus. Regarding peri-implantitis, the diagnosis and severity of the disease should be evaluated primarily based on clinical parameters and on radiological findings based on periapical radiographs (two dimensional). The use of cone beam computed tomography scans in clinical research might not yield any evident beneficial effect for the patient included. As many of the cone beam computed tomography scans performed for research have no direct therapeutic consequence, dose optimization measures should be implemented by using appropriate exposure parameters and by reducing the field of view to the actual region of interest.

  20. Current Treatment Limitations in Age-Related Macular Degeneration and Future Approaches Based on Cell Therapy and Tissue Engineering

    Directory of Open Access Journals (Sweden)

    P. Fernández-Robredo

    2014-01-01

    Full Text Available Age-related macular degeneration (AMD is the leading cause of blindness in the Western world. With an ageing population, it is anticipated that the number of AMD cases will increase dramatically, making a solution to this debilitating disease an urgent requirement for the socioeconomic future of the European Union and worldwide. The present paper reviews the limitations of the current therapies as well as the socioeconomic impact of the AMD. There is currently no cure available for AMD, and even palliative treatments are rare. Treatment options show several side effects, are of high cost, and only treat the consequence, not the cause of the pathology. For that reason, many options involving cell therapy mainly based on retinal and iris pigment epithelium cells as well as stem cells are being tested. Moreover, tissue engineering strategies to design and manufacture scaffolds to mimic Bruch’s membrane are very diverse and under investigation. Both alternative therapies are aimed to prevent and/or cure AMD and are reviewed herein.

  1. Transcranial direct-current stimulation induced in stroke patients with aphasia: a prospective experimental cohort study

    Directory of Open Access Journals (Sweden)

    Michele Devido Santos

    Full Text Available CONTEXT AND OBJECTIVE: Previous animal and human studies have shown that transcranial direct current stimulation can induce significant and lasting neuroplasticity and may improve language recovery in patients with aphasia. The objective of the study was to describe a cohort of patients with aphasia after stroke who were treated with transcranial direct current stimulation. DESIGN AND SETTING: Prospective cohort study developed in a public university hospital. METHODS: Nineteen patients with chronic aphasia received 10 transcranial direct current stimulation sessions lasting 20 minutes each on consecutive days, using a current of 2 mA. The anode was positioned over the supraorbital area and the cathode over the contralateral motor cortex. The following variables were analyzed before and after the 10 neuromodulation sessions: oral language comprehension, copying, dictation, reading, writing, naming and verbal fluency. RESULTS: There were no adverse effects in the study. We found statistically significant differences from before to after stimulation in relation to simple sentence comprehension (P = 0.034, naming (P = 0.041 and verbal fluency for names of animals (P = 0.038. Improved scores for performing these three tasks were seen after stimulation. CONCLUSIONS: We observed that excitability of the primary motor cortex through transcranial direct current stimulation was associated with effects on different aspects of language. This can contribute towards future testing in randomized controlled trials.

  2. Multi-scale model of resistive-type superconducting fault current limiters based on 2G HTS coated conductors

    Science.gov (United States)

    Bonnard, Charles-Henri; Sirois, Frédéric; Lacroix, Christian; Didier, Gaëtan

    2017-01-01

    In order to plan the integration of superconducting fault current limiters (SFCLs) in power systems, accurate models of SFCLs must be made available in commercial power system transient simulators. In this context, we developed such a model for the EMTP-RV software package, a power system transient simulator widely used by power utilities. The model can be used with any resistive-type SFCL (rSFCL) made of high temperature superconductor (HTS) tapes, which are discretized in ‘electro-thermal elements’. Those elements consist solely of electric circuit components, and are used to represent portions of tape of various sizes and dimensions (a ‘multi-scale’ approach). Both the electrical and thermal behaviors of the tape are modeled, including interfacial effects, nonlinear properties of materials and heat transfer to the surrounding environment. Such a multi-scale model can simulate accurately both the local quench dynamics of HTS tapes (microscopic scale) and the global impact of the rSFCL on the power system (macroscopic/system scale). In this paper, the model is used to compute phenomena such as propagation velocity of a hot spot and heat diffusion through the thickness of the tape. Results were verified by comparing EMTP-RV results with finite element simulations. In addition to the development of the multi-scale model itself, which is the major contribution of this paper, the use of the model allowed us to determine the conditions of validity of the commonly used ‘homogenization’ of the thermal properties across the tape thickness. Indeed, when the current flowing into the rSFCL is slightly above its critical current I c (and up to 2{I}{{c}}), very important errors in the power waveforms arise, leading to potentially wrong decisions of protection systems. Homogenized thermal models should thus be used with great care in practice.

  3. Single-Case Experimental Design: Current Standards and Applications in Occupational Therapy.

    Science.gov (United States)

    Lane, Justin D; Ledford, Jennifer R; Gast, David L

    Occupational therapy is a field with a long-standing history of recommending and implementing interventions designed to improve the quality of life of clients with disabilities. Often, the interventions are individualized to meet the needs of this diverse group of clients in dynamic settings. Identifying effective and efficient interventions for such a diverse group of clients and settings requires a flexible research approach. Single-case experimental designs (SCEDs) allow practitioners and researchers to answer experimental questions within the context of rigorous research designs. The purpose of this article is to highlight the similarities between the mission of occupational therapy and SCEDs. Recommendations for designing single-case studies with the framework provided by the Single-Case Reporting Guideline in Behavioral Interventions are provided. In addition, common problems and proposed solutions, along with implications for practitioners and researchers, are provided. Copyright © 2017 by the American Occupational Therapy Association, Inc.

  4. The case for a directional dark matter detector and the status of current experimental efforts

    CERN Document Server

    Ahlen, S; Battat, J B R; Billard, J; Bozorgnia, N; Burgos, S; Caldwell, T; Carmona, J M; Cebrián, S; Colas, P; Dafni, T; Daw, E; Dujmic, D; Dushkin, A; Fedus, W; Ferrer, E; Finkbeiner, D; Fisher, P H; Forbes, J; Fusayasu, T; Galan, J; Gamble, T; Ghag, C; Giomataris, Yu; Gold, M; Gomez, H; Gómez, M E; Gondolo, P; Green, A; Grignon, C; Guillaudin, O; Hagemann, C; Hattori, K; Henderson, S; Higashi, N; Ida, C; Iguaz, F J; Inglis, A; Irastorza, I G; Iwaki, S; Kaboth, A; Kabuki, S; Kadyk, J; Kallivayalil, N; Kubo, H; Kurosawa, S; Kudryavtsev, V A; Lamy, T; Lanza, R; Lawson, T B; Lee, A; Lee, E R; Lin, T; Loomba, D; López, J; Luzón, G; Manobu, T; Martoff, J; Mayet, F; McCluskey, B; Miller, E; Miuchi, K; Monroe, J; Morgan, B; Muna, D; Murphy, A St J; Naka, T; Nakamura, K; Nakamura, M; Nakano, T; Nicklin, G G; Nishimura, H; Niwa, K; Paling, S M; Parker, J; Petkov, A; Pipe, M; Pushkin, K; Robinson, M; Rodríguez, A; Rodríguez-Quintero, J; Sahin, T; Sanderson, R; Sanghi, N; Santos, D; Sato, O; Sawano, T; Sciolla, G; Sekiya, H; Slatyer, T R; Snowden-Ifft, D P; Spooner, N J C; Sugiyama, A; Takada, A; Takahashi, M; Takeda, A; Tanimori, T; Taniue, K; Tomas, A; Tomita, H; Tsuchiya, K; Turk, J; Tziaferi, E; Ueno, K; Vahsen, S; Vanderspek, R; Vergados, J; Villar, J A; Wellenstein, H; Wolfe, I; Yamamoto, R K; Yegoryan, H

    2010-01-01

    We present the case for a dark matter detector with directional sensitivity. This document was developed at the 2009 CYGNUS workshop on directional dark matter detection, and contains contributions from theorists and experimental groups in the field. We describe the need for a dark matter detector with directional sensitivity; each directional dark matter experiment presents their project's status; and we close with a feasibility study for scaling up to a one ton directional detector, which would cost around $150M.

  5. Experimental Test of Alternating-Current Zeeman Interference Effect in Ramsey Separated Oscillating Fields

    Institute of Scientific and Technical Information of China (English)

    ZHANG Jun-Hai; WANG Feng-Zhi; YANG Dong-Hai

    2004-01-01

    An experimental test of ac Zeeman effect in an optically pumped caesium beam frequency standard is reported and analysed. An interference pattern of the atomic energy level shift as a function of the applied microwave field near the atomic transition frequency was observed. It was superimposed on the dispersion lineshape of a normal ac Zeeman effect. This effect was analysed with the atomic wavefunction phase analysing method.

  6. A study of experimental evaluations of neural network learning algorithms: current research practice

    OpenAIRE

    Prechelt, Lutz

    2007-01-01

    113 articles about neural network learning algorithms published in 1993 and 1994 are examined for the amount of experimental evaluation they contain. Every third of them does employ not even a single realistic or real learning problem. Only 6% of all articles present results for more than one problem using real world data.Furthermore, one third of all articles does not present any quantitative comparison with a previously known algorithm. These results indicate that the q...

  7. Experimental study on bed-load sediment transport under irregular wave and current combined flow

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Using an irregularly oscillating tray and flume, a series of experiments are completed to evaluate bed-load sediment transport rate under irregular wave- current coexistent fild. Testing conditions include three interaction angles 0°, 45°, 90° and two kinds of median sizes (0.38 and 1.10 mm).The results of transport rate show that the net sediment transport rate can be expressed approximately as the function of the maximum bottom shear stress of waves, mean shear stress of current and the grain size.

  8. 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.

  9. CD73 is expressed by inflammatory Th17 cells in experimental autoimmune encephalomyelitis but does not limit differentiation or pathogenesis

    Science.gov (United States)

    Hernandez-Mir, Gerard

    2017-01-01

    CD73 works together with CD39 to convert extracellular ATP to immunoregulatory adenosine, thus inhibiting inflammation. TGFβ-mediated CD73 expression on ‘regulatory’ Th17 cells limits their ability to eradicate tumors, similar to the immunosuppressive mechanism described for CD73 on Tregs. However, CD73 is also expressed on Th17 cells thought to be inflammatory in Crohn’s disease. CD73 has previously been reported to contribute to inflammation in the central nervous system (CNS). In experimental autoimmune encephalomyelitis (EAE), we found that inflammatory cytokine-producing Th17 cells showed increased CD73 expression as disease progressed. We therefore hypothesized that CD73 could be important for limiting the expansion or pathogenic function of Th17 cells in autoimmune inflammation of the CNS. Surprisingly, EAE development was not enhanced or inhibited by CD73 deficiency; there was correspondingly no difference in induction of Th17-associated cytokines IL-17, IFNγ or GM-CSF or recruitment of either inflammatory or regulatory cells to the central nervous system. We confirmed that CD73 was similarly not required for differentiation of Th17 cells in vitro. These data show that while CD73 expression is regulated during EAE, this enzyme is not absolutely required to either promote or limit Th17 cell expansion or EAE severity. PMID:28288184

  10. Experimental and numerical determination of thermal forming limit diagrams (TFLD) of high strength steel 22MnB5

    Science.gov (United States)

    Shi, D. Y.; Ying, L.; Hu, P.; Lu, J. D.; Zhao, X.; Liu, W. Q.

    2013-05-01

    High strength steel components are increasingly being considered for use in vehicle structures due to the potential for higher strength to weight ratio, fuel economy improvement and emission reduction. However, high strength steel's poor ductility at room temperature requires sheet forming to be carried out in hot forming method. The Thermal Forming Limit Diagram (TFLD) is an important primary criterion to determine how close the sheet metal is to tearing when it is formed into a product shape in hot forming process. In this work, an efficient experimental set-up named TFLD 300 which is based on Nakajima test has been developed. Several experiments for hot forming limits of high strength steel 22MnB5 were performed and the forming limit curves at different temperatures are obtained. Then the three-dimensional TFLD which considers temperature history and strain path is constructed. As an evaluation criterion for formability, the three-dimensional TFLD is introduced into KMAS (King Mesh Analysis System), which is independently developed commercial CAE software and can be used for hot forming simulation. Subsequently, a typical B-pillar's hot forming process with varying process conditions have been simulated by using the KMAS software. And the corresponding experiment results confirm that the KMAS software and three-dimensional TFLD can accurately predict the fracture of sheet metal in hot forming.

  11. The Integration of Family and Group Therapy as an Alternative to Juvenile Incarceration: A Quasi-Experimental Evaluation Using Parenting with Love and Limits.

    Science.gov (United States)

    Karam, Eli A; Sterrett, Emma M; Kiaer, Lynn

    2017-06-01

    The current study employed a quasi-experimental design using both intent-to-treat and protocol adherence analysis of 155 moderate- to high-risk juvenile offenders to evaluate the effectiveness of Parenting with Love and Limits® (PLL), an integrative group and family therapy approach. Youth completing PLL had significantly lower rates of recidivism than the comparison group. Parents also reported statistically significant improvements in youth behavior. Lengths of service were also significantly shorter for the treatment sample than the matched comparison group by an average of 4 months. This study contributes to the literature by suggesting that intensive community-based combined family and group treatment is effective in curbing recidivism among high-risk juveniles. © 2015 Family Process Institute.

  12. Experimental and numerical analyses of high voltage 4H-SiC junction barrier Schottky rectifiers with linearly graded field limiting ring

    Science.gov (United States)

    Wang, Xiang-Dong; Deng, Xiao-Chuan; Wang, Yong-Wei; Wang, Yong; Wen, Yi; Zhang, Bo

    2014-05-01

    This paper describes the successful fabrication of 4H-SiC junction barrier Schottky (JBS) rectifiers with a linearly graded field limiting ring (LG-FLR). Linearly variable ring spacings for the FLR termination are applied to improve the blocking voltage by reducing the peak surface electric field at the edge termination region, which acts like a variable lateral doping profile resulting in a gradual field distribution. The experimental results demonstrate a breakdown voltage of 5 kV at the reverse leakage current density of 2 mA/cm2 (about 80% of the theoretical value). Detailed numerical simulations show that the proposed termination structure provides a uniform electric field profile compared to the conventional FLR termination, which is responsible for 45% improvement in the reverse blocking voltage despite a 3.7% longer total termination length.

  13. Current methods of the modeling of experimental diabetes mellitus type 2: a literature review

    Directory of Open Access Journals (Sweden)

    Yu. M. Kolesnyk

    2016-01-01

    Full Text Available Background. Diabetes mellitus (DM became a major problem of the healthcare in Ukraine. The rapid increase in the incidence was noticed especially in recent decade. The treatment of diabetes and its complications become a difficult task. From this standpoint the experimental modeling of diabetes is rather essential. Using the experimental models gives the possibility to assess the significance of the activity of pharmacological substances or to find out new mechanism in the action of medicaments. The aim of this review is to light up the most studied and common experimental models of diabetes mellitus type 2 (T2DM in small rodents and find out their drawbacks. It is known the background of T2DM is the violation of the insulin homeostasis such as the resistance of peripheral tissues to insulin as well as the dysfunction of the pancreatic beta-cells, which both lead to appearance of such phenomena as the glucosetoxicity and the lipotoxicity. In the end they both could result in life threatening vascular complications. Considering the steady growth of T2DM patients, the development both of the drug and non-drug methods of its treatment with the high therapeutically efficiency and the perfect safety profile becomes essential. The most important stage of the search of new ways of influence on pathogenetic links of T2DM is the preclinical stage. From this standpoint the usage of experimental models of T2DM has a huge importance. There are a lot of models of T2DM developed by different scientists. These models could be spontaneous or be induced by different chemical diabetogenic substances, diet or surgical interventions or be a combination of methods listed above. Conclusions. We should underline the adequate modeling of DM2T is the necessary basis for the pre-clinical study of drug-based and not-drug methods of correction of the hyperglycemic states. Using different models makes it possible for infer the obtained experimental results to the society

  14. Experimental results of current distribution in Rutherford-type LHC cables

    CERN Document Server

    Verweij, A P

    2000-01-01

    Current distribution among the wires of multi-strand superconducting cables is an important item for accelerator magnets. A non-uniform distribution could cause additional field distortions in the magnet bore and can as well be one of the reasons of premature quenching. Since two years electrical measurements on superconducting Rutherford-type cables are performed at CERN as part of the reception tests for the Large Hadron Collider (LHC). Cable samples of 2.4 m length are tested at currents up to 32 kA, temperatures around 1.9 and 4.3 K, and fields up to 10 T, applied perpendicularly as well as parallel to the broad face of the cable. Last year, an array of 24 Hall probes was installed in the test set-up in order to measure the self-field of the cable samples along one cable pitch. Each of the probes measures the local field generated by the current in the strands close by, and the results of the all probes reflect therefore the distribution of the strand currents. Experiments are done varying the applied fie...

  15. Resonance Chiral Lagrangian Currents and Experimental Data for $\\tau^-\\to\\pi^{-}\\pi^{-}\\pi^{+}\

    CERN Document Server

    Nugent, I M; Roig, P; Shekhovtsova, O; Was, Z

    2013-01-01

    In this paper we document the modifications introduced to the previous version of the Resonance Chiral Lagrangian current ({\\it Phys.Rev.} {\\bf D86} (2012) 113008) of the $\\tau^\\pm \\to \\pi^\\pm \\pi^\\pm \\pi^\\mp \

  16. Experimental Study on the Influence of AC Stray Current on the Cathodic Protection of Buried Pipe

    Directory of Open Access Journals (Sweden)

    Qingmiao Ding

    2016-01-01

    Full Text Available The size of the damaged area of the coating and its position on the pipeline impacted the cathodic protection potential, and there was a damaged area of the greatest impact value. When damaged area was 300 mm2, the IR drop was the largest, and this situation could easily lead to inadequate protection; when the parallel spacing between pipeline and interference source was unchanged, the measured value curves of cathodic protection potential presented “U” shaped trend with the increasing stray current interference intensity. Under certain parallel spacing between pipeline and interference source, high alternating stray current intensity would cause serious negative offsets, so that the overprotection of the pipeline occurred, and make the coating crack; there was a parallel threshold length. When less than the threshold, the pipe-ground potential increases rapidly with the parallel length increasing. In order to judge whether a pipeline was interference by AC stray current and the risk of stray current corrosion, we should make a comprehensive analysis of the cathodic protection energizing potential, the switch-off potential, AC pipe-soil potential, IR drops, and so on.

  17. Protobacco Media Exposure and Youth Susceptibility to Smoking Cigarettes, Cigarette Experimentation, and Current Tobacco Use among US Youth.

    Directory of Open Access Journals (Sweden)

    Erika B Fulmer

    Full Text Available Youth are exposed to many types of protobacco influences, including smoking in movies, which has been shown to cause initiation. This study investigates associations between different channels of protobacco media and susceptibility to smoking cigarettes, cigarette experimentation, and current tobacco use among US middle and high school students.By using data from the 2012 National Youth Tobacco Survey, structural equation modeling was performed in 2013. The analyses examined exposure to tobacco use in different channels of protobacco media on smoking susceptibility, experimentation, and current tobacco use, accounting for perceived peer tobacco use.In 2012, 27.9% of respondents were never-smokers who reported being susceptible to trying cigarette smoking. Cigarette experimentation increased from 6.3% in 6th grade to 37.1% in 12th grade. Likewise, current tobacco use increased from 5.2% in 6th grade to 33.2% in 12th grade. Structural equation modeling supported a model in which current tobacco use is associated with exposure to static advertising through perception of peer use, and by exposure to tobacco use depicted on TV and in movies, both directly and through perception of peer use. Exposure to static advertising appears to directly increase smoking susceptibility but indirectly (through increased perceptions of peer use to increase cigarette experimentation. Models that explicitly incorporate peer use as a mediator can better discern the direct and indirect effects of exposure to static advertising on youth tobacco use initiation.These findings underscore the importance of reducing youth exposure to smoking in TV, movies, and static advertising.

  18. Erosion Control of Scour during Construction; Report 3. Experimental Measurements of Refraction, Diffraction, and Current Patterns Near Jetties.

    Science.gov (United States)

    1980-09-01

    predict the probable magnitude of (Continued) DD vi’Ra 03 1wom or INov OM @ISDETR Unclassified S.CUm TY CLAS-.lCATIO OF THIS PAS.. (..m 0. Yw...transport of the bottom material at the particular site. The purpose of this study was to obtain detailed and precise experimental data regarding wave...currents. This removal of material from around structures is often not compensated by an influx of additional material ; the result is scour, or

  19. Experimental investigations of electric current under transverse and longitudinal electric field in uniaxially deformed p-Ge

    Science.gov (United States)

    Abramov, A. A.; Akimov, V. I.; Dalakyan, A. T.; Tulupenko, Victor N.; Zaitsev, A. M.; Danilov, S. N.; Firsov, D. A.; Shalygin, V. A.

    1999-11-01

    Comparison between cases of longitudinal and transverse directions of uniaxial pressure and strong electric field, affected the bulk hole germanium, to use it for lasting in far IR region has been carried out. Conclusion about preference of crossed directions is made. Threshold pressure, at which stimulated radiation arises, independence of crystallographic direction, along which external influences are applied, is also discussed. The results of experimental investigations of the crossed directions of uniaxial pressure and electric current are given.

  20. Experimental study on a wide range of wave and current conditions of the WEPTOS Wave Energy Converter

    DEFF Research Database (Denmark)

    Pecher, Arthur; Kofoed, Jens Peter

    This report presents the results of an experimental study that was performed on small scale model that was a replication of the full-scale Weptos WEC intended for DanWEC. The tests were performed in the circular basin at FloWave at Edinburgh University in October 2014. The laboratory facilities h...... the capabilities to have simultaneously currents and waves from any possible direction and also to produce advanced wave specifications....

  1. Numerical simulation and experimental study of the hydrodynamics of a modeled reef located within a current

    Institute of Scientific and Technical Information of China (English)

    姜昭阳; 梁振林; 唐衍力; 黄六一; 于定勇; 姜曼松

    2010-01-01

    The hydrodynamic forces and flow field of artificial reef models in steady flow were numerically investigated using the RNG k–εturbulent model.The numerical simulation results are consistent with results observed by experimental means.A comparative study indicates that the corresponding errors of forces between calculated values and values observed in the experiment vary in the range of 2.3%–11.2%and that the corresponding errors of velocities vary in the range of 1.3%–15.8%. The flow field numerical result...

  2. Survey of Current Experimental Studies of Effects of Traditional Chinese Medicine on Peripheral Nerve Regeneration

    Institute of Scientific and Technical Information of China (English)

    WU Qun-li; LIANG Xiao-chun

    2006-01-01

    The repairing and regeneration of peripheral nerves is a very complex biological and cytological process, its mechanism is unclear so far, and thus results in the lack of specific and effectual therapy and medicament. Chinese herbs and their effective components have their own inimitable predominance in promoting peripheral nerve regeneration, such as their multi-factorial, multi-target and multi-functional action, abundant source, inexpensive, etc. In this paper, the experimental studies reported in recent 5 years concerning the effects of Chinese herbs or their active components on peripheral nerve repairing and regeneration are reviewed in respects of the integral level, cellular level, molecular level and gene level.

  3. Minimum quench power dissipation and current non-uniformity in international thermonuclear experimental reactor type NbTi cable-in-conduit conductor samples under direct current conditions

    Science.gov (United States)

    Rolando, G.; van Lanen, E. P. A.; Nijhuis, A.

    2012-05-01

    The level of current non-uniformity in NbTi cable-in-conduit conductors (CICCs) sections near the joints in combination with the magnetic field profile needs attention in view of proper joint design. The strand joule power and current distribution at quench under DC conditions of two samples of ITER poloidal field coil conductors, as tested in the SULTAN facility, and of the so called PFCI model coil insert, have been analyzed with the numerical cable model JackPot. The precise trajectories of all individual strands, joint design, cabling configuration, spatial distribution of the magnetic field, sample geometry, and experimentally determined interstrand resistance distributions have been taken into account. Although unable to predict the quench point due to the lack of a thermal-hydraulic routine, the model allows to assess the instantaneous strand power at quench and its local distribution in the cable once the quench conditions in terms of current and temperature are experimentally known. The analysis points out the relation of the above mentioned factors with the DC quench stability of both short samples and coils. The possible small scale and local electrical-thermal interactions were ignored in order to examine the relevance of such effects in the overall prediction of the CICC performance. The electromagnetic code shows an excellent quantitative predictive potential for CICC transport properties, excluding any freedom for matching the results. The influence of the local thermal effects in the modeling is identified as being marginal and far less than the generally accepted temperature margin for safe operation.

  4. Experimental study on hydrodynamic characteristics of vertical-axis floating tidal current energy power generation device

    Science.gov (United States)

    Ma, Yong; Li, Teng-fei; Zhang, Liang; Sheng, Qi-hu; Zhang, Xue-wei; Jiang, Jin

    2016-10-01

    To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device (VAFTCEPGD), a prototype is designed and experiment is carried out in the towing tank. Free decay is conducted to obtain attenuation characteristics of the VAFTCEPGD, and characteristics of mooring forces and motion response, floating condition, especially the lateral displacement of the VAFTCEPGD are obtained from the towing in still water. Tension response of the #1 mooring line and vibration characteristics of the VAFTCEPGD in regular waves as well as in level 4 irregular wave sea state with the current velocity of 0.6 m/s. The results can be reference for theoretical study and engineering applications related to VAFTCEPGD.

  5. Foreign Languages in Vienna Primary Schools – in Mainstream Education and in Current Experimental Models

    Directory of Open Access Journals (Sweden)

    Renate Seebauer

    2015-05-01

    Full Text Available Starting with a short retrospective and an overview of the incorporation of foreign language learning into the Austrian curriculum for primary schools the paper in hand describes the current situation of foreign language teaching in primary schools as well as various current models of foreign language education in primary schools in Vienna (school year 1 to 4. In terms of objectives these models exceed the requirements of the curriculum of the formal education system or regard themselves as quantitative and qualitative enrichment. They follow different didactic approaches and/or site-specific characteristics and needs. The formulation of basic skills is to be understood as an attempt to find a common basis of output indicators and to facilitate the transition to secondary education. Although English is the most commonly chosen resp. offered language the paper also refers to school experiments that focus on Romance or Slavic languages or on languages of Austra’s neighbouring countries.

  6. Experimental investigation of quasiperiodic-chaotic-quasiperiodic-chaotic transition in a direct current magnetron sputtering plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sabavath, Gopi Kishan; Banerjee, I.; Mahapatra, S. K., E-mail: skmahapatra@bitmesra.ac.in [Plasma Laboratory, Department of Physics, Birla Institute of Technology-Mesra, Ranchi 835215 (India); Shaw, Pankaj Kumar; Sekar Iyengar, A. N. [Plasma Physics Division, Saha Institute of Nuclear Physics, 1/AF, Bidhannagar, Kolkata 700064 (India)

    2015-08-15

    Floating potential fluctuations from a direct current magnetron sputtering plasma have been analysed using time series analysis techniques like phase space plots, power spectra, frequency bifurcation plot, etc. The system exhibits quasiperiodic-chaotic-quasiperiodic-chaotic transitions as the discharge voltage was increased. The transitions of the fluctuations, quantified using the largest Lyapunov exponent, have been corroborated by Hurst exponent and the Shannon entropy. The Shannon entropy is high for quasiperiodic and low for chaotic oscillations.

  7. Experimental studies on benzene carcinogenicity at the Bologna Institute of Oncology: current results and ongoing research.

    Science.gov (United States)

    Maltoni, C; Conti, B; Cotti, G; Belpoggi, F

    1985-01-01

    In 1977 Maltoni and Scarnato were the first to demonstrate that benzene is an experimental carcinogen in rats. With that and other experiments, Maltoni et al have shown that benzene administered by ingestion (stomach tube) or inhalation is a multipotential carcinogen in rats (of two different strains) and mice and produces a variety of tumors, namely: Zymbal gland carcinomas, oral and nasal cavity carcinomas, skin carcinomas, acanthomas, dysplasias and carcinomas of forestomach, mammary malignant tumors, hepatomas, liver angiosarcomas, hemolymphoreticular neoplasias, and pulmonary tumors. The incidence of Zymbal gland carcinomas and carcinomas of the oral and nasal cavities is affected by the length of treatment by inhalation and by the age of animals. However, the available epidemiological and experimental data at present do not provide precise information on the risk of doses around or below 10 ppm. Long-term carcinogenicity bioassays at 50, 25, 10, 5 and 1 ppm may be helpful for scientific risk assessment. In addition, these experiments have shown that toluene, xylene, and ethylbenzene, at high concentrations, cause an increase in the number of total malignant tumors.

  8. Single-Case Experimental Designs: A Systematic Review of Published Research and Current Standards

    Science.gov (United States)

    Smith, Justin D.

    2013-01-01

    This article systematically reviews the research design and methodological characteristics of single-case experimental design (SCED) research published in peer-reviewed journals between 2000 and 2010. SCEDs provide researchers with a flexible and viable alternative to group designs with large sample sizes. However, methodological challenges have precluded widespread implementation and acceptance of the SCED as a viable complementary methodology to the predominant group design. This article includes a description of the research design, measurement, and analysis domains distinctive to the SCED; a discussion of the results within the framework of contemporary standards and guidelines in the field; and a presentation of updated benchmarks for key characteristics (e.g., baseline sampling, method of analysis), and overall, it provides researchers and reviewers with a resource for conducting and evaluating SCED research. The results of the systematic review of 409 studies suggest that recently published SCED research is largely in accordance with contemporary criteria for experimental quality. Analytic method emerged as an area of discord. Comparison of the findings of this review with historical estimates of the use of statistical analysis indicates an upward trend, but visual analysis remains the most common analytic method and also garners the most support amongst those entities providing SCED standards. Although consensus exists along key dimensions of single-case research design and researchers appear to be practicing within these parameters, there remains a need for further evaluation of assessment and sampling techniques and data analytic methods. PMID:22845874

  9. Glazed clay pottery and lead exposure in Mexico: Current experimental evidence.

    Science.gov (United States)

    Diaz-Ruiz, Araceli; Tristán-López, Luis Antonio; Medrano-Gómez, Karen Itzel; Torres-Domínguez, Juan Alejandro; Ríos, Camilo; Montes, Sergio

    2017-11-01

    Lead exposure remains a significant environmental problem; lead is neurotoxic, especially in developing humans. In Mexico, lead in human blood is still a concern. Historically, much of the lead exposure is attributed to the use of handcrafted clay pottery for cooking, storing and serving food. However, experimental cause-and-effect demonstration is lacking. The present study explores this issue with a prospective experimental approach. We used handcrafted clay containers to prepare and store lemonade, which was supplied as drinking water to pregnant rats throughout the gestational period. We found that clay pots, jars, and mugs leached on average 200 µg/l lead, and exposure to the lemonade resulted in 2.5 µg/dl of lead in the pregnant rats' blood. Neonates also showed increased lead content in the hippocampus and cerebellum. Caspase-3 activity was found to be statistically increased in the hippocampus in prenatally exposed neonates, suggesting increased apoptosis in that brain region. Glazed ceramics are still an important source of lead exposure in Mexico, and our results confirm that pregnancy is a vulnerable period for brain development.

  10. The Importance and Current Limitations of Planetary Boundary Layer (PBL) Retrieval from Space for Land-Atmosphere Coupling Studies

    Science.gov (United States)

    Santanello, J. A., Jr.; Schaefer, A.

    2016-12-01

    There is an established need for improved PBL remote sounding over land for hydrology, land-atmosphere (L-A), PBL, cloud/convection, pollution/chemistry studies and associated model evaluation and development. Most notably, the connection of surface hydrology (through soil moisture) to clouds and precipitation relies on proper quantification of water's transport through the coupled system, which is modulated strongly by PBL structure, growth, and feedback processes such as entrainment. In-situ (ground-based or radiosonde) measurements will be spatially limited to small field campaigns for the foreseeable future, so satellite data is a must in order to understand these processes globally. The scales of these applications require diurnal resolution (e.g. 3-hourly or finer) at PBL coupling and water and energy cycles at their native scales. Today's satellite sensors (e.g. advanced IR, GEO, lidar, GPS-RO) do not reach close to these targets in terms of accuracy or resolution, and each of these sensors has some advantages but even more limitations that make them impractical for PBL and L-A studies. Unfortunately, there is very little attention or planning (short or long-term) in place for improving lower tropospheric sounding over land, and as a result PBL and L-A interactions have been identified as `gaps' in current programmatic focal areas. It is therefore timely to assess how these technologies can be leveraged, combined, or evolved in order to form a dedicated mission or sub-mission to routinely monitor the PBL on diurnal timescales. In addition, improved PBL monitoring from space needs to be addressed in the next Decadal Survey. In this talk, the importance of PBL information (structure, evolution) for L-A coupling diagnostics and model development will be summarized. The current array of PBL retrieval methods and products from space will then be assessed in terms of meeting the needs of these models, diagnostics, and scales, with a look forward as to how this can

  11. Current and experimental treatments of Parkinson disease: A guide for neuroscientists.

    Science.gov (United States)

    Oertel, Wolfgang; Schulz, Jörg B

    2016-10-01

    Over a period of more than 50 years, the symptomatic treatment of the motor symptoms of Parkinson disease (PD) has been optimized using pharmacotherapy, deep brain stimulation, and physiotherapy. The arsenal of pharmacotherapies includes L-Dopa, several dopamine agonists, inhibitors of monoamine oxidase (MAO)-B and catechol-o-methyltransferase (COMT), and amantadine. In the later course of the disease, motor complications occur, at which stage different oral formulations of L-Dopa or dopamine agonists with long half-life, a transdermal application or parenteral pumps for continuous drug supply can be subscribed. Alternatively, the patient is offered deep brain stimulation of the subthalamic nucleus (STN) or the internal part of the globus pallidus (GPi). For a more efficacious treatment of motor complications, new formulations of L-Dopa, dopamine agonists, and amantadine as well as new MAO-B and COMT inhibitors are currently tested in clinical trials, and some of them already yielding positive results in phase 3 trials. In addition, non-dopaminergic agents have been tested in the early clinical phase for the treatment of motor fluctuations and dyskinesia, including adenosine A2A antagonists (istradefylline, preladenant, and tozadenant) and modulators of the metabolic glutamate receptor 5 (mGluR5 - mavoglurant) and serotonin (eltoprazine) receptors. Recent clinical trials testing coenzyme Q10, the dopamine agonist pramipexole, creatine monohydrate, pioglitazone, or AAV-mediated gene therapy aimed at increasing expression of neurturin, did not prove efficacious. Treatment with nicotine, caffeine, inosine (a precursor of urate), and isradipine (a dihydropyridine calcium channel blocker), as well as active and passive immunization against α-synuclein and inhibitors or modulators of α-synuclein-aggregation are currently studied in clinical trials. However, to date, no disease-modifying treatment is available. We here review the current status of treatment options for

  12. Targeting host syntaxin-5 preferentially blocks Leishmania parasitophorous vacuole development in infected cells and limits experimental Leishmania infections.

    Science.gov (United States)

    Canton, Johnathan; Kima, Peter E

    2012-10-01

    Our previous observations established a role for syntaxin-5 in the development of Leishmania parasitophorous vacuoles (LPVs). In this study, we took advantage of the recent identification of Retro-2, a small organic molecule that can cause the redistribution of syntaxin-5; we show herein that Retro-2 blocks LPV development within 2 hours of adding it to cells infected with Leishmania amazonensis. In infected cells incubated for 48 hours with Retro-2, LPV development was significantly limited; furthermore, infected cells harbored four to five times fewer parasites than infected cells incubated in vehicle alone. In vivo studies revealed that Retro-2 curbed experimental L. amazonensis infections in a dose-dependent manner. Retro-2 did not have any appreciable effect on the host cell physiological characteristics; furthermore, it had no apparent toxicity in experimental animals. An unexpected, but welcome, finding was that Retro-2 inhibited the replication of Leishmania parasites in axenic cultures. This study is significant because it identifies an endoplasmic reticulum/Golgi SNARE as a potential target for the control of Leishmania infections; moreover, it suggests that small organic molecules can be identified that can selectively disrupt the vesicle fusion machinery that promotes the development of pathogen-containing compartments without exerting toxic effects on the host.

  13. Current Status of Clinical and Experimental Researches on Cognitive Impairment in Diabetes

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    This article reviews the clinical and experimental researches on cognitive impairment related to diabetes in the recent decade. Most clinical studies indicate that the cognitive impairment in patients with type 1 diabetes mellitus is related to recurrent hypoglycemia closely. There is little research about whether or not hyperglycemia is related to cognitive impairment in patients with type 1 diabetes mellitus. Most studies indicate that the cognitive impairment in type 2 diabetes involves multiple factors through multiple mechanisms, including blood glucose, blood lipid, blood pressure, level of insulin, medication, chronic complication, etc. But, there has been no large-scale, multi-center, randomized controlled clinical trial in China recently. And what is more, some problems exist in this field of research, such as the lack of golden criterion of cognitive function measurement, different population of studied objects, and incomprehensive handling of confounding factors. Experimental studies found that hippocampal long-term potentiation (LTP) was impaired,which were manifested by impairment of spatial memory and decreased expression of LTP, but its relation to hyperglycemia, the duration of diabetes, learning and memory has always been differently reported by different researches. Thus, there are a lot of unknown things to be explored and studied in order to clarify its mechanism. TCM has abundant clinical experience in treating cerebral disease with medicine that enforces the kidney and promotes wit. However, there has been no research on treating diabetic cognitive impairment,which requires work to be done actively and TCM to be put into full play, in order to improve the treatment of diabetes and enhance living quality of patients.

  14. Study of recovery characteristics of 2nd generation HTS tapes with different stabilizers for resistive type superconducting fault current limiters

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, Jie, E-mail: 1988725sheng@163.com; Zeng, Weina; Ma, Jun; Yao, Zhihao; Li, Zhuyong; Jin, Zhijian; Hong, Zhiyong

    2016-02-15

    Highlights: • Three methods of measuring the recovery time of HTS tapes are compared. • Four tapes with different stabilizers were tested to compare their recovery characteristics. • The HTS tapes with thinner stabilizers have better recovery characteristics. • Encapsulation makes the recovery characteristics of HTS tapes worse. • The results can be reference of the re-reclosed operation time interval. - Abstract: The resistive type superconducting fault current limiter (SFCL) is one of the most important superconducting power applications nowadays. As known, this type of SFCL is settled directly in the power transmission line. When a short fault happens, the temperature of the superconductors in the SFCL will increase sharply due to the huge generated heat. This means the superconductors need time to recover the superconducting properties and be ready for the next short fault. So the recovery characteristics become one of the most crucial features of the resistive type SFCL. In this paper, several different kinds of measuring methods are presented to calculate the recovery time of the HTS tapes, and comparison of these methods is also carried out by a standard test. On basis of this, samples with different kinds of stabilizers are used to explore the influence of stabilizer on their recovery characteristics. In addition, the influence of the encapsulation technology is also discussed in this paper.

  15. Imaging of Myocardial Fibrosis in Patients with End-Stage Renal Disease: Current Limitations and Future Possibilities

    Science.gov (United States)

    Patel, A. S.; Marsh, A.-M.; McAdam, J.; McCann, G. P.; Burton, J. O.

    2017-01-01

    Cardiovascular disease in patients with end-stage renal disease (ESRD) is driven by a different set of processes than in the general population. These processes lead to pathological changes in cardiac structure and function that include the development of left ventricular hypertrophy and left ventricular dilatation and the development of myocardial fibrosis. Reduction in left ventricular hypertrophy has been the established goal of many interventional trials in patients with chronic kidney disease, but a recent systematic review has questioned whether reduction of left ventricular hypertrophy improves cardiovascular mortality as previously thought. The development of novel imaging biomarkers that link to cardiovascular outcomes and that are specific to the disease processes in ESRD is therefore required. Postmortem studies of patients with ESRD on hemodialysis have shown that the extent of myocardial fibrosis is strongly linked to cardiovascular death and accurate imaging of myocardial fibrosis would be an attractive target as an imaging biomarker. In this article we will discuss the current imaging methods available to measure myocardial fibrosis in patients with ESRD, the reliability of the techniques, specific challenges and important limitations in patients with ESRD, and how to further develop the techniques we have so they are sufficiently robust for use in future clinical trials.

  16. Classification of chronic rhinosinusitis according to a nasal polyp and tissue eosinophilia: limitation of current classification system for Asian population

    Science.gov (United States)

    Cho, Sung-Woo; Kim, Dae Woo; Kim, Jeong-Whun; Lee, Chul Hee

    2017-01-01

    Chronic rhinosinusitis (CRS) can be classified according to the presence of a nasal polyp (NP): CRS with NP (CRSwNP) and CRS without NP (CRSsNP). CRSwNP has characteristics with high infiltration of tissue eosinophilia with a burst of Th2 inflammatory cytokine. However recent findings in Eastern Asia countries suggest that CRSwNP can be divided according to the presence of tissue eosinophilia. Thus, CRSwNP can be classified into eosinophilic and noneosinophilic. Eosinophilic CRSwNP seems to have different immunological and clinical feature compared to noneosinophilic CRSwNP. From the same point of view, CRSsNP can also be divided according to tissue eosinophilia. However, the meaning of this dichotomous categorization in CRS seems to be not quite clear. This review focus on the limitations in current subclassification of CRS according to the presence of NP and tissue eosinophilia and discuss other factors related to tissue remodeling and NP generation which may provide clues for the further understanding of CRS pathogenesis. PMID:28765816

  17. The first Italian Superconducting Fault Current Limiter: Results of the field testing experience after one year operation

    Science.gov (United States)

    Martini, L.; Bocchi, M.; Ascade, M.; Valzasina, A.; Rossi, V.; Ravetta, C.; Angeli, G.

    2014-05-01

    Ricerca sul Sistema Energetico S.p.A. (RSE) has been gaining a relevant experience in the simulation, design and installation of resistive-type Superconducting Fault Current Limiter (SFCL) devices for more than five years in the framework of a R&D national project funded by the Ricerca di Sistema (RdS). The most recent outcome of this research activity is the installation of a resistive-type BSCCO-based 9 kV / 3.4 MVA SFCL device in a single feeder branch of the Medium Voltage (MV) distribution network managed by A2A Reti Elettriche S.p.A (A2A) in the Milano area. This installation represents the first SFCL successfully installed in Italy. In this paper, we report on the main outcomes after a more than 1-year long steady-state field testing activity. The design of an upgraded device to be installed in the same substation has already been initiated: the new SFCL will allow to protect four different feeders, therefore implying a device upgrade up to 15.6 MVA.

  18. The LLNL High Accuracy Volume Renderer for Unstructured Data: Capabilities, Current Limits, and Potential for ASCI/VIEWS Deployment

    Energy Technology Data Exchange (ETDEWEB)

    Williams, P L; Max, N L

    2001-06-04

    This report describes a volume rendering system for unstructured data, especially finite element data, that creates images with very high accuracy. The system will currently handle meshes whose cells are either linear or quadratic tetrahedra, or meshes with mixed cell types: tetrahedra, bricks, prisms, and pyramids. The cells may have nonplanar facets. Whenever possible, exact mathematical solutions for the radiance integrals and for interpolation are used. Accurate semitransparent shaded isosurfaces may be embedded in the volume rendering. For very small cells, subpixel accumulation by splatting is used to avoid sampling error. A new exact and efficient visibility ordering algorithm is described. The most accurate images are generated in software, however, more efficient algorithms utilizing graphics hardware may also be selected. The report describes the parallelization of the system for a distributed-shared memory multiprocessor machine, and concludes by discussing the system's limits, desirable future work, and ways to extend the system so as to be compatible with projected ASCI/VIEWS architectures.

  19. Secondary current properties generated by wind-induced water waves in experimental conditions

    Directory of Open Access Journals (Sweden)

    Michio Sanjou

    2014-06-01

    Full Text Available Secondary currents such as the Langmuir circulation are of high interest in natural rivers and the ocean because they have striking impacts on scour, sedimentation, and mass transport. Basic characteristics have been well-studied in straight open-channel flows. However, little is known regarding secondary circulation induced by wind waves. The presented study describes the generation properties of wind waves observed in the laboratory tank. Wind-induced water waves are known to produce large scale circulations. The phenomenon is observed together with high-speed and low-speed streaks, convergence and divergence zones, respectively. Therefore, it is important to determine the hydrodynamic properties of secondary currents for wind-induced water waves within rivers and lakes. In this study, using two high-speed CMOS cameras, stereoscopic particle image velocimetry (PIV measurements were conducted in order to reveal the distribution of all three components of velocity vectors. The experiments allowed us to investigate the three-dimensional turbulent structure under water waves and the generation mechanism of large-scale circulations. Additionally, a third CMOS camera was used to measure the spanwise profile of thefree-surface elevation. The time-series of velocity components and the free-surface were obtained simultaneously. From our experiments, free-surface variations were found to influence the instantaneous velocity distributions of the cross-sectional plane. We also considered thegeneration process by the phase analysis related to gravity waves and compared the contribution of the apparent stress.

  20. New hadronic currents in TAUOLA: for confrontation with the experimental data

    CERN Document Server

    Was, Z

    2012-01-01

    The status of implementation of new hadronic currents into the Monte Carlo system for simulation of tau-lepton production and decay in high-energy accelerator experiments is reviewed. Since the tau-lepton conference in 2010 substantial progress was achieved: (i) For the TAUOLA Monte Carlo generator of tau-lepton decays, automated and simultaneous use of many versions of form factors for the calculation of optional weights for fits was developed and checked to work in the Belle and BaBar software environment. Alternative parameterizations of hadronic currents based on the Resonance Chiral approach are available now. This was achieved for more than 88% of the total tau hadronic width. (ii) the TAUOLA universal interface based on HepMC (the C++ event record) is available. This is the case for C++ users of PHOTOS Monte Carlo for radiative corrections in decays, as well. An algorithm for weighted events to explore spin effects in analysis of hard processes was prepared. (iii) Kernels featuring a complete first-ord...

  1. New hadronic currents in TAUOLA: for confrontation with the experimental data

    Energy Technology Data Exchange (ETDEWEB)

    Was, Z. [Institute of Nuclear Physics, Polish Academy of Sciences, ul. Radzikowskiego 152, 31-342 Cracow (Poland); CERN, 1211 Geneva (Switzerland)

    2012-04-15

    The status of implementation of new hadronic currents into the Monte Carlo system for simulation of {tau}-lepton production and decay in high-energy accelerator experiments is reviewed. Since the {tau}-lepton conference in 2010 substantial progress was achieved: (i) For the TAUOLA Monte Carlo generator of {tau}-lepton decays, automated and simultaneous use of many versions of form factors for the calculation of optional weights for fits was developed and checked to work in the Belle and BaBar software environment. Alternative parameterizations of hadronic currents based on the Resonance Chiral approach are available now. This was achieved for more than 88% of the total {tau} hadronic width. (ii) the TAUOLA universal interface based on HepMC (the C++ event record) is available. This is the case for C++ users of PHOTOS Monte Carlo for radiative corrections in decays, as well. An algorithm for weighted events to explore spin effects in analysis of hard processes was prepared. (iii) Kernels featuring a complete first-order matrix element are available now for PHOTOS users interested in decays of Z and W bosons. New tests with different options of matrix elements for those and for K{sub l3} decays are available as well. Presented results illustrate the status of the projects performed in collaboration with Zofia Czyczula, Nadia Davidson, Tomasz Przedzinski, Olga Shekhovtsova, Elzbieta Richter-Was, Pablo Roig, Qingjun Xu and others.

  2. An Experimental Study on the Darrieus-Savonius Turbine for the Tidal Current Power Generation

    Science.gov (United States)

    Kyozuka, Yusaku

    The Darrieus turbine is popular for tidal current power generation in Japan. It is simple in structure with straight wings rotating around a vertical axis, so that it has no directionality against the motion of tidal flow which changes its direction twice a day. However, there is one defect in the Darrieus turbine; its small starting torque. Once it stops, a Darrieus turbine is hard to re-start until a fairly fast current is exerted on it. To improve the starting torque of the Darrieus turbine used for tidal power generation, a hybrid turbine, composed of a Darrieus turbine and a Savonius rotor is proposed. Hydrodynamic characteristics of a semi-circular section used for the Savonius bucket were measured in a wind tunnel. The torque of a two bucket Savonius rotor was measured in a circulating water channel, where four different configurations of the bucket were compared. A combined Darrieus and Savonius turbine was tested in the circulating water channel, where the effect of the attaching angle between Darrieus wing and Savonius rotor was studied. Finally, power generation experiments using a 48 pole electric generator were conducted in a towing tank and the power coefficients were compared with the results of experiments obtained in the circulating water channel.

  3. Experimental and Numerical Study of Wave-Induced Long-Shore Currents on A Mild Slope Beach

    Institute of Scientific and Technical Information of China (English)

    SUN Tao; TAO Jian-hua

    2005-01-01

    The long-shore current distribution on a mild slope beach is studied by combining the numerical model and the physical experiment. The experiments of long-shore currents under the action of regular and irregular waves are conducted on mild beaches with different slopes in a wave basin. A numerical model is established, which includes a wave propagation model, a wave breaking model and a long-shore current model. The validity of the numerical model is proved by the comparison of its results with the results of the experimental model. It is concluded that the wave-induced long-shore current is influenced significantly by the incident wave height, the wave angle and the beach slope. Its application to the Bohai Bay indicates that the wave-induced currents have the same order of magnitude as the tide currents in the near-shore zone of mill slope beach. In the design of wastewater outfall locations on a mild-slope beach with shallow water of the Bohai Bay, the position of the outfall should be 10 km away from the shoreline, which is outside of the surf-zone.

  4. Current meter components and other data from FIXED PLATFORMS from the SW Atlantic (limit-20 W) from 27 January 1986 to 01 April 1987 (NODC Accession 8800329)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current meter components data were collected from FIXED PLATFORMS in the SW Atlantic (limit-20 W) from 27 January 1986 to 01 April 1987. Data were collected by...

  5. Current meter components and other data from FIXED PLATFORMS from NE Pacific (limit-180) from 25 April 1984 to 01 May 1990 (NODC Accession 9100018)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Current meter components data were collected from FIXED PLATFORMS in the NE Pacific (limit-180) from 25 April 1984 to 01 May 1990. Data were collected by the Pacific...

  6. [Regeneration of endocrine gastroenteropancreatic system in experimental and clinical pathology: concept development and current problems].

    Science.gov (United States)

    Ivanova, V F

    2013-01-01

    Literature review contains the literature data and the results of author's own investigations describing the coming into being and the development of the concepts on the regeneration of endocrine gastroenteropancreatic (GEP) system under the conditions of norm, experimental and clinical pathology. Data analysis permitted to reveal the similarities and differences in the course of this process in various organs of the digestive system. Endocrine GEP system renewal occurs at different levels of its organization. At the tissue level, the endocrine cells renewal occurs via the transformation of exocrine cells into the endocrine ones and as a result of differentiation from stem cells via the "agranular" cell stage which are precursors of the endocrine cells. This pathway of regeneration is the major one after the damage. Regeneration at cellular level occurs through mitotic division of the differentiated endocrine cells (early stage of regeneration) and as a result of the formation granules with different hormonal profile in D-cells. At the intracellular level, the regeneration is realized through the intracellular structure restoration after their damage induced by the increase of cell functional activity accompanied by degranulation and dystrophic changes development

  7. Experimental Estimating Deflection of a Simple Beam Bridge Model Using Grating Eddy Current Sensors

    Directory of Open Access Journals (Sweden)

    Hui Zhao

    2012-07-01

    Full Text Available A novel three-point method using a grating eddy current absolute position sensor (GECS for bridge deflection estimation is proposed in this paper. Real spatial positions of the measuring points along the span axis are directly used as relative reference points of each other rather than using any other auxiliary static reference points for measuring devices in a conventional method. Every three adjacent measuring points are defined as a measuring unit and a straight connecting bar with a GECS fixed on the center section of it links the two endpoints. In each measuring unit, the displacement of the mid-measuring point relative to the connecting bar measured by the GECS is defined as the relative deflection. Absolute deflections of each measuring point can be calculated from the relative deflections of all the measuring units directly without any correcting approaches. Principles of the three-point method and displacement measurement of the GECS are introduced in detail. Both static and dynamic experiments have been carried out on a simple beam bridge model, which demonstrate that the three-point deflection estimation method using the GECS is effective and offers a reliable way for bridge deflection estimation, especially for long-term monitoring.

  8. Approach to Recover Hydrocarbons from Currently Off-Limit Areas of the Antrim Formation, MI Using Low-Impact Technologies

    Energy Technology Data Exchange (ETDEWEB)

    James Wood; William Quinlan

    2008-09-30

    The goal of this project was to develop and execute a novel drilling and completion program in the Antrim Shale near the western shoreline of Northern Michigan. The target was the gas in the Lower Antrim Formation (Upper Devonian). Another goal was to see if drilling permits could be obtained from the Michigan DNR that would allow exploitation of reserves currently off-limits to exploration. This project met both of these goals: the DNR (Michigan Department of Natural Resources) issued permits that allow drilling the shallow subsurface for exploration and production. This project obtained drilling permits for the original demonstration well AG-A-MING 4-12 HD (API: 21-009-58153-0000) and AG-A-MING 4-12 HD1 (API: 21-009-58153-0100) as well as for similar Antrim wells in Benzie County, MI, the Colfax 3-28 HD and nearby Colfax 2-28 HD which were substituted for the AG-A-MING well. This project also developed successful techniques and strategies for producing the shallow gas. In addition to the project demonstration well over 20 wells have been drilled to date into the shallow Antrim as a result of this project's findings. Further, fracture stimulation has proven to be a vital step in improving the deliverability of wells to deem them commercial. Our initial plan was very simple; the 'J-well' design. We proposed to drill a vertical or slant well 30.48 meters (100 feet) below the glacial drift, set required casing, then angle back up to tap the resource lying between the base to the drift and the conventional vertical well. The 'J'-well design was tested at Mancelona Township in Antrim County in February of 2007 with the St. Mancelona 2-12 HD 3.

  9. Current radiological techniques used to evaluate unilateral partial ureteral obstruction: an experimental rabbit study.

    Science.gov (United States)

    Yazıcı, Mehmet; Celebi, Suleyman; Kuzdan, Özgür; Koçan, Hüseyin; Ayyıldız, Halil Suat; Bayrak, İlkay Koray; Bilgici, Meltem Ceyhan; Yapıcı, Oktay; Kefeli, Mehmet; Arıtürk, Ender

    2015-07-01

    The aim of this study was to evaluate functional and prognostic benefits of Doppler ultrasonography (DU), diuretic renal scintigraphy (DRS), and magnetic resonance urography (MRU) during diagnosis and follow-up of ureteropelvic junction obstruction (UPJO) and to examine apoptosis rates caused by UPJO in an experimental rabbit model. Twenty-four rabbits were divided randomly into two groups. The left kidneys of 15 rabbits from the first group underwent Ulm-Miller surgery to create UPJO, whereas the left kidneys of nine rabbits from the second group underwent sham surgery. A pressure flow study (Whitaker's test) was done during postoperative week 6. Based on the Whitaker test, the DU, DRS, and MRU findings were compared. The number of apoptotic renal cells was counted after death. The Whitaker test run during postoperative week 6 revealed obstructions in 15 rabbits from group 1; the nine rabbits of the sham group had no obstructions. Sensitivity and specificity of DRS were 93.3 and 88.8 %, respectively, and those of MRU were 93.3 and 88.8 %, respectively. The postoperative mean RI values were significantly higher than the preoperative values, associated with sensitivity of 86.6 % and specificity of 77.5 % for detecting UPJO. DRS, MRU, and RI could not predict UPJO in one (8 %), one (8 %), and two (16 %) kidneys, respectively. Likelihood ratio (LR) was 8.4 for MRU and scintigraphy, while for RI, LR was 3.9. Pathology specimens revealed that all kidneys with UPJO underwent apoptosis, and the number of apoptotic cells was significantly higher on the UPJO-created side than on the contralateral and in the sham group (p < 0.05). No test predicted all apoptosis related to UPJO. The RI, DRS, and DMRU results correlated with the pressure flow results for detecting UPJO. No single radiological technique predicted all initial UPJO-created kidneys that concluded with apoptosis. Further studies are required to seek with better methods for diagnosing an obstruction or to define a

  10. Experimental and Numerical Study on Forming Limit Diagrams of 304 Stainless Steel Tubes in the Hydroforming Process

    Science.gov (United States)

    Naghibi, Mahdi Falahati; Gerdooei, Mahdi; Jooybari, Mohammad Bakhshi

    2016-12-01

    Tearing as a factor that restricts formability of sheets and tubes is determined by forming limit diagram (FLD). The aim of the current study is to present a novel approach to achieve FLD of a metallic tube using hydroforming process. Here, for 304 stainless steel tubes, various loading conditions, namely free loading, bulging with axial feeding and bulging with closed end, were considered. Along with loading condition, die geometries with different corner radius and deformation width were studied on the strain path and plastic instability. The effects of process parameters on the strain path have been evaluated and simulated using ABAQUS/Explicit. Meshed tubes were bulged under controlled loading, and the FLD was drawn after measuring the major and minor strains close to the tearing location. Finally, the evaluation of the current method has been investigated by using the obtained FLD in the forming of an industrial part (i.e., the cam-shaped tube). The results revealed that the proposed approach has the capability to predict the formability of industrial components.

  11. Current and future experimental strategies for structural analysis of trichothecene mycotoxins--a prospectus.

    Science.gov (United States)

    Shank, Roxanne A; Foroud, Nora A; Hazendonk, Paul; Eudes, François; Blackwell, Barbara A

    2011-12-01

    Fungal toxins, such as those produced by members of the order Hypocreales, have widespread effects on cereal crops, resulting in yield losses and the potential for severe disease and mortality in humans and livestock. Among the most toxic are the trichothecenes. Trichothecenes have various detrimental effects on eukaryotic cells including an interference with protein production and the disruption of nucleic acid synthesis. However, these toxins can have a wide range of toxicity depending on the system. Major differences in the phytotoxicity and cytotoxicity of these mycotoxins are observed for individual members of the class, and variations in toxicity are observed among different species for each individual compound. Furthermore, while diverse toxicological effects are observed throughout the whole cellular system upon trichothecene exposure, the mechanism of toxicity is not well understood. In order to comprehend how these toxins interact with the cell, we must first have an advanced understanding of their structure and dynamics. The structural analysis of trichothecenes was a subject of major interest in the 1980s, and primarily focused on crystallographic and solution-state Nuclear Magnetic Resonance (NMR) spectroscopic studies. Recent advances in structural determination through solution- and solid-state NMR, as well as computation based molecular modeling is leading to a resurgent interest in the structure of these and other mycotoxins, with the focus shifting in the direction of structural dynamics. The purpose of this work is to first provide a brief overview of the structural data available on trichothecenes and a characterization of the methods commonly employed to obtain such information. A summary of the current understanding of the relationship between structure and known function of these compounds is also presented. Finally, a prospectus on the application of new emerging structural methods on these and other related systems is discussed.

  12. Current and Future Experimental Strategies for Structural Analysis of Trichothecene Mycotoxins—A Prospectus

    Directory of Open Access Journals (Sweden)

    Barbara A. Blackwell

    2011-12-01

    Full Text Available Fungal toxins, such as those produced by members of the order Hypocreales, have widespread effects on cereal crops, resulting in yield losses and the potential for severe disease and mortality in humans and livestock. Among the most toxic are the trichothecenes. Trichothecenes have various detrimental effects on eukaryotic cells including an interference with protein production and the disruption of nucleic acid synthesis. However, these toxins can have a wide range of toxicity depending on the system. Major differences in the phytotoxicity and cytotoxicity of these mycotoxins are observed for individual members of the class, and variations in toxicity are observed among different species for each individual compound. Furthermore, while diverse toxicological effects are observed throughout the whole cellular system upon trichothecene exposure, the mechanism of toxicity is not well understood. In order to comprehend how these toxins interact with the cell, we must first have an advanced understanding of their structure and dynamics. The structural analysis of trichothecenes was a subject of major interest in the 1980s, and primarily focused on crystallographic and solution-state Nuclear Magnetic Resonance (NMR spectroscopic studies. Recent advances in structural determination through solution- and solid-state NMR, as well as computation based molecular modeling is leading to a resurgent interest in the structure of these and other mycotoxins, with the focus shifting in the direction of structural dynamics. The purpose of this work is to first provide a brief overview of the structural data available on trichothecenes and a characterization of the methods commonly employed to obtain such information. A summary of the current understanding of the relationship between structure and known function of these compounds is also presented. Finally, a prospectus on the application of new emerging structural methods on these and other related systems is

  13. Epigenetics and sex-specific fitness: an experimental test using male-limited evolution in Drosophila melanogaster.

    Directory of Open Access Journals (Sweden)

    Jessica K Abbott

    Full Text Available When males and females have different fitness optima for the same trait but share loci, intralocus sexual conflict is likely to occur. Epigenetic mechanisms such as genomic imprinting (in which expression is altered according to parent-of-origin and sex-specific maternal effects have been suggested as ways by which this conflict can be resolved. However these ideas have not yet been empirically tested. We designed an experimental evolution protocol in Drosophila melanogaster that enabled us to look for epigenetic effects on the X-chromosome-a hotspot for sexually antagonistic loci. We used special compound-X females to enforce father-to-son transmission of the X-chromosome for many generations, and compared fitness and gene expression levels between Control males, males with a Control X-chromosome that had undergone one generation of father-son transmission, and males with an X-chromosome that had undergone many generations of father-son transmission. Fitness differences were dramatic, with experimentally-evolved males approximately 20% greater than controls, and with males inheriting a non-evolved X from their father about 20% lower than controls. These data are consistent with both strong intralocus sexual conflict and misimprinting of the X-chromosome under paternal inheritance. However, expression differences suggested that reduced fitness under paternal X inheritance was largely due to deleterious maternal effects. Our data confirm the sexually-antagonistic nature of Drosophila's X-chromosome and suggest that the response to male-limited X-chromosome evolution entails compensatory evolution for maternal effects, and perhaps modification of other epigenetic effects via coevolution of the sex chromosomes.

  14. The yeast three-hybrid system as an experimental platform to identify proteins interacting with small signaling molecules in plant cells: Potential and limitations

    Directory of Open Access Journals (Sweden)

    Stéphanie eCottier

    2011-12-01

    Full Text Available Chemical genetics is a powerful scientific strategy that utilizes small bioactive molecules as experimental tools to unravel biological processes. Bioactive compounds occurring in nature represent an enormous diversity of structures that can be used to dissect functions of biological systems. Once the bioactivity of a natural or synthetic compound has been critically evaluated the challenge remains to identify its molecular target and mode of action, which usually is a time consuming and labor-intensive process. To facilitate this task, we decided to implement the yeast three-hybrid (Y3H technology as a general experimental platform to scan the whole Arabidopsis proteome for targets of small signaling molecules. The Y3H technology is based on the yeast two-hybrid system and allows direct cloning of proteins that interact in vivo with a synthetic hybrid ligand, which comprises the biologically active molecule of interest covalently linked to methotrexate (Mtx. In yeast nucleus the hybrid ligand connects two fusion proteins: the Mtx part binding to dihydrofolate reductase fused to a DNA binding domain (encoded in the yeast strain, and the bioactive molecule part binding to its potential protein target fused to a DNA activating domain (encoded on a cDNA expression vector. During cDNA library screening, the formation of this ternary, transcriptional activator complex leads to reporter gene activation in yeast cells, and thereby allows selection of the putative targets of small bioactive molecules of interest. Here we present the strategy and experimental details for construction and application of a Y3H platform, including chemical synthesis of different hybrid ligands, construction of suitable cDNA libraries, the choice of yeast strains, and appropriate screening conditions. Based on the results obtained and the current literature we discussed the perspectives and limitations of the Y3H approach for identifying targets of small bioactive molecules.

  15. Are current disease-modifying therapeutics in multiple sclerosis justified on the basis of studies in experimental autoimmune encephalomyelitis?

    Science.gov (United States)

    Farooqi, Nasr; Gran, Bruno; Constantinescu, Cris S

    2010-11-01

    The precise aetio-pathology of multiple sclerosis remains elusive. However, important recent advances have been made and several therapies have been licensed for clinical use. Many of these were developed, validated or tested in the animal model, experimental autoimmune encephalomyelitis (EAE). This systematic review aims to assess whether the current disease modifying treatments and those that are the closest to the clinic are justified on the basis of the results of EAE studies. We discuss some aspects of the utility and caveats of EAE as a model for multiple sclerosis drug development.

  16. Complementary numerical–experimental benchmarking for shape optimization and validation of structures subjected to wave and current forces

    DEFF Research Database (Denmark)

    Markus, D.; Ferri, Francesco; Wüchner, R.

    2015-01-01

    that focuses on differences in load curves resulting from 2D and 3D flows. It is shown that the major trends predicted by the numerical simulations are also captured in the experiment, highlighting the potential of CFD as a powerful tool for shape optimization studies. The overall aim of the paper...... variations of the structure on the resulting horizontal forces. Steady current conditions, dynamic loading due to waves, and combined wave–current scenarios are considered. A clear focus is put on simplicity and reproducibility, allowing for efficient testing of related methods and codes. This is achieved...... by defining a simple test geometry, altered in one design variable only, and by designing the test case such that a two dimensional analysis of the flow fields is possible. The force sensitivities to changes in the geometry are determined both numerically and experimentally for a great bandwidth of different...

  17. Analytical magnetic torque calculations and experimental testing of radial flux permanent magnet-type eddy current brakes

    Science.gov (United States)

    Choi, Jang-Young; Jang, Seok-Myeong

    2012-04-01

    This paper reports on analytical magnetic torque calculations and experimental tests of a radial flux permanent magnet (RFPM)-type eddy current brake (ECB). Analytical solutions for permanent magnet-generated magnetic fields that consider the eddy current reaction are obtained by using a magnetic vector potential and a two dimensional (2D) polar coordinate system. On the basis of these solutions, the analytical expressions for a magnetic torque are also derived. All analytical results are validated extensively by non-linear finite element calculations. In particular, magnetic torque measurements are obtained in tests to confirm the analyses. Finally, practical issues related to the analytical study of RFPM-type ECBs are fully discussed.

  18. Assessment of buckling-restrained braced frame reliability using an experimental limit-state model and stochastic dynamic analysis

    Science.gov (United States)

    Andrews, Blake M.; Song, Junho; Fahnestock, Larry A.

    2009-09-01

    Buckling-restrained braces (BRBs) have recently become popular in the United States for use as primary members of seismic lateral-force-resisting systems. A BRB is a steel brace that does not buckle in compression but instead yields in both tension and compression. Although design guidelines for BRB applications have been developed, systematic procedures for assessing performance and quantifying reliability are still needed. This paper presents an analytical framework for assessing buckling-restrained braced frame (BRBF) reliability when subjected to seismic loads. This framework efficiently quantifies the risk of BRB failure due to low-cycle fatigue fracture of the BRB core. The procedure includes a series of components that: (1) quantify BRB demand in terms of BRB core deformation histories generated through stochastic dynamic analyses; (2) quantify the limit-state of a BRB in terms of its remaining cumulative plastic ductility capacity based on an experimental database; and (3) evaluate the probability of BRB failure, given the quantified demand and capacity, through structural reliability analyses. Parametric studies were conducted to investigate the effects of the seismic load, and characteristics of the BRB and BRBF on the probability of brace failure. In addition, fragility curves (i.e., conditional probabilities of brace failure given ground shaking intensity parameters) were created by the proposed framework. While the framework presented in this paper is applied to the assessment of BRBFs, the modular nature of the framework components allows for application to other structural components and systems.

  19. Assessment of buckling-restrained braced frame reliability using an experimental limit-state model and stochastic dynamic analysis

    Institute of Scientific and Technical Information of China (English)

    Blake M. Andrews; Junho Song; Larry A. Fahnestock

    2009-01-01

    Buckling-restrained braces (BRBs) have recently become popular in the United :States for use as primary members of seismic lateral-force-resisting systems. A BRB is a steel brace that does not buckle in compression but instead yields in both tension and compression. Although design guidelines for BRB applications have been developed, systematic procedures for assessing performance and quantifying reliability are still needed. This paper presents an analytical framework for assessing buckling-restrained braced frame (BRBF) reliability when subjected to seismic loads. This framework efficiently quantifies the risk of BRB failure due to low-cycle fatigue fracture of the BRB core. The procedure includes a series of components that: (1) quantify BRB demand in terms of BRB core deformation histories generated through stochastic dynamic analyses; (2) quantify the limit-state of a BRB in terms of its remaining cumulative plastic ductility capacity based on an experimental database; and (3) evaluate the probability of BRB failure, given the quantified demand and capacity, through structural reliability analyses. Parametric studies were conducted to investigate the effects of the seismic load, and characteristics of the BRB and BRBF on the probability of brace failure. In addition, fragility curves (i.e., conditional probabilities of brace failure given ground shaking intensity parameters) were created by the proposed framework. While the framework presented in this paper is applied to the assessment of BRBFs, the modular nature of the framework components allows for application to other structural components and systems.

  20. Monitoring tooth profile faults in epicyclic gearboxes using synchronously averaged motor currents: Mathematical modeling and experimental validation

    Science.gov (United States)

    Ottewill, J. R.; Ruszczyk, A.; Broda, D.

    2017-02-01

    Time-varying transmission paths and inaccessibility can increase the difficulty in both acquiring and processing vibration signals for the purpose of monitoring epicyclic gearboxes. Recent work has shown that the synchronous signal averaging approach may be applied to measured motor currents in order to diagnose tooth faults in parallel shaft gearboxes. In this paper we further develop the approach, so that it may also be applied to monitor tooth faults in epicyclic gearboxes. A low-degree-of-freedom model of an epicyclic gearbox which incorporates the possibility of simulating tooth faults, as well as any subsequent tooth contact loss due to these faults, is introduced. By combining this model with a simple space-phasor model of an induction motor it is possible to show that, in theory, tooth faults in epicyclic gearboxes may be identified from motor currents. Applying the synchronous averaging approach to experimentally recorded motor currents and angular displacements recorded from a shaft mounted encoder, validate this finding. Comparison between experiments and theory highlight the influence of operating conditions, backlash and shaft couplings on the transient response excited in the currents by the tooth fault. The results obtained suggest that the method may be a viable alternative or complement to more traditional methods for monitoring gearboxes. However, general observations also indicate that further investigations into the sensitivity and robustness of the method would be beneficial.

  1. Comparison of the quench and fault current limiting characteristics of the flux-coupling type SFCL with single and three-phase transformer

    Science.gov (United States)

    Jung, Byung Ik; Cho, Yong Sun; Park, Hyoung Min; Chung, Dong Chul; Choi, Hyo Sang

    2013-01-01

    The South Korean power grid has a network structure for the flexible operation of the system. The continuously increasing power demand necessitated the increase of power facilities, which decreased the impedance in the power system. As a result, the size of the fault current in the event of a system fault increased. As this increased fault current size is threatening the breaking capacity of the circuit breaker, the main protective device, a solution to this problem is needed. The superconducting fault current limiter (SFCL) has been designed to address this problem. SFCL supports the stable operation of the circuit breaker through its excellent fault-current-limiting operation [1-5]. In this paper, the quench and fault current limiting characteristics of the flux-coupling-type SFCL with one three-phase transformer were compared with those of the same SFCL type but with three single-phase transformers. In the case of the three-phase transformers, both the superconducting elements of the fault and sound phases were quenched, whereas in the case of the single-phase transformer, only that of the fault phase was quenched. For the fault current limiting rate, both cases showed similar rates for the single line-to-ground fault, but for the three-wire earth fault, the fault current limiting rate of the single-phase transformer was over 90% whereas that of the three-phase transformer was about 60%. It appears that when the three-phase transformer was used, the limiting rate decreased because the fluxes by the fault current of each phase were linked in one core. When the power loads of the superconducting elements were compared by fault type, the initial (half-cycle) load was great when the single-phase transformer was applied, whereas for the three-phase transformer, its power load was slightly lower at the initial stage but became greater after the half fault cycle.

  2. Fault-current predetermination using time-limited CT secondary side measurements by the covariance-Prony method

    Energy Technology Data Exchange (ETDEWEB)

    Kamel, N.; Sankaran, P.; Venkatesh, B. [Multimedia Univ. (Malaysia)

    2004-11-01

    Protective current transformers (CTs) are integrated into electrical power systems for assessment of the health of the system. They are intended to provide a scaled-down value of the line current. During major faults, excessive fault currents with decaying DC components could flow through the primary of the CT, causing core saturation and a consequent malfunction of the protection system. This problem is addressed in the paper, and a signal-processing scheme is proposed for fast predetermination of the peak value of the steady-state AC component, instant of occurrence of fault and the time constant of the decaying direct current. Samples of the CT secondary current are collected until the onset of saturation, and are operated upon using a covariance-Prony algorithm to estimate the aforementioned critical parameters. Simulation results in support of the proposed technique are also presented. (author)

  3. Studies of challenge in lower hybrid current drive capability at high density regime in experimental advanced superconducting tokamak

    Science.gov (United States)

    Ding, B. J.; Li, M. H.; Li, Y. C.; Wang, M.; Liu, F. K.; Shan, J. F.; Li, J. G.; Wan, B. N.; Wan

    2017-02-01

    Aiming at a fusion reactor, two issues must be solved for the lower hybrid current drive (LHCD), namely good lower hybrid wave (LHW)-plasma coupling and effective current drive at high density. For this goal, efforts have been made to improve LHW-plasma coupling and current drive capability at high density in experimental advanced superconducting tokamak (EAST). LHW-plasma coupling is improved by means of local gas puffing and gas puffing from the electron side is taken as a routine way for EAST to operate with LHCD. Studies of high density experiments suggest that low recycling and high lower hybrid (LH) frequency are preferred for LHCD experiments at high density, consistent with previous results in other machines. With the combination of 2.45 GHz and 4.6 GHz LH waves, a repeatable high confinement mode plasma with maximum density up to 19~\\text{m}-3$ was obtained by LHCD in EAST. In addition, in the first stage of LHCD cyclic operation, an alternative candidate for more economical fusion reactors has been demonstrated in EAST and further work will be continued.

  4. An improved low-voltage ride-through performance of DFIG based wind plant using stator dynamic composite fault current limiter.

    Science.gov (United States)

    Gayen, P K; Chatterjee, D; Goswami, S K

    2016-05-01

    In this paper, an enhanced low-voltage ride-through (LVRT) performance of a grid connected doubly fed induction generator (DFIG) has been presented with the usage of stator dynamic composite fault current limiter (SDCFCL). This protection circuit comprises of a suitable series resistor-inductor combination and parallel bidirectional semiconductor switch. The SDCFCL facilitates double benefits such as reduction of rotor induced open circuit voltage due to increased value of stator total inductance and concurrent increase of rotor impedance. Both effects will limit rotor circuit over current and over voltage situation more secured way in comparison to the conventional scheme like the dynamic rotor current limiter (RCL) during any type of fault situation. The proposed concept is validated through the simulation study of the grid integrated 2.0MW DFIG.

  5. Decrease of a Current Mediated by Kv1.3 Channels Causes Striatal Cholinergic Interneuron Hyperexcitability in Experimental Parkinsonism

    Directory of Open Access Journals (Sweden)

    Cecilia Tubert

    2016-09-01

    Full Text Available The mechanism underlying a hypercholinergic state in Parkinson’s disease (PD remains uncertain. Here, we show that disruption of the Kv1 channel-mediated function causes hyperexcitability of striatal cholinergic interneurons in a mouse model of PD. Specifically, our data reveal that Kv1 channels containing Kv1.3 subunits contribute significantly to the orphan potassium current known as IsAHP in striatal cholinergic interneurons. Typically, this Kv1 current provides negative feedback to depolarization that limits burst firing and slows the tonic activity of cholinergic interneurons. However, such inhibitory control of cholinergic interneuron excitability by Kv1.3-mediated current is markedly diminished in the parkinsonian striatum, suggesting that targeting Kv1.3 subunits and their regulatory pathways may have therapeutic potential in PD therapy. These studies reveal unexpected roles of Kv1.3 subunit-containing channels in the regulation of firing patterns of striatal cholinergic interneurons, which were thought to be largely dependent on KCa channels.

  6. Current limitations in super-resolution fluorescence microscopy for biological specimens: How deep can we go from the cover glass?

    Science.gov (United States)

    Okada, Yasushi

    2017-04-01

    Diffraction limit of resolution has been one of the biggest limitations in the optical microscopy. Super-resolution fluorescence microscopy has enabled us to break this limit. However, for the observations of real biological specimens, especially for the imaging of tissues or whole body, the target structures of interest are often embedded deep inside the specimen. Here, we would present our results to extend the target of the super-resolution microscopy deeper into the cells. Confocal microscope optics work effectively to minimize the effect by the aberrations by the cellular components, but at the expense of the signal intensities. Spherical aberrations by the refractive index mismatch between the cellular environment and the immersion liquid can be much larger, but can be reduced by adjusting the correction collar at the objective lens.

  7. buffer Layer Growth, the Thickness Dependence of Jc in Coated Conductors, Local Identification of Current Limiting Mechanisms and Participation in the Wire Development Group

    Energy Technology Data Exchange (ETDEWEB)

    Larbalestier, David; Hellstron, Eric; Abraimov, Dmytro

    2011-12-17

    The primary thrusts of our work were to provide critical understanding of how best to enhance the current-carrying capacity of coated conductors. These include the deconstruction of Jc as a function of fim thickness, the growth of in situ films incorporating strong pinning centers and the use of a suite of position-sensitive tools that enable location and analysis of key areas where current-limiting occurs.

  8. An experimental investigation of the dynamics of submarine leveed channel initiation as sediment-laden density currents experience sudden unconfinement

    Energy Technology Data Exchange (ETDEWEB)

    Rowland, Joel C [Los Alamos National Laboratory; Hilley, George E [STANFORD UNIV; Fildani, Andrea [CHEVRON ETC

    2009-01-01

    Leveed submarine channels play a critical role in the transfer of sediment from the upper continental slopes to interslope basins and ultimately deepwater settings. Despite a reasonable understanding of how these channels grow once established, how such channels initiate on previously unchannelized portions of the seafloor remains poorly understood. We conducted a series of experiments that elucidate the influence of excess density relative to flow velocity on the dynamics of, and depositional morphologies arising from, density currents undergoing sudden unconfinement across a sloped bed. Experimental currents transported only suspended sediment across a non-erodible substrate. Under flow conditions ranging from supercritical to subcritical (bulk Richardson numbers of 0.02 to 1.2) our experiments failed to produce deposits resembling or exhibiting the potential to evolve into self-formed leveed channels. In the absence of excess density, a submerged sediment-laden flow produced sharp crested lateral deposits bounding the margins of the flow for approximately a distance of two outlet widths down basin. These lateral deposits terminated in a centerline deposit that greatly exceeded marginal deposits in thickness. As excess density increased relative to the outlet velocity, the rate of lateral spreading of the flow increased relative to the downstream propagation of the density current, transitioning from a narrow flow aligned with the channel outlet to a broad radially expanding flow. Coincident with these changes in flow dynamics, the bounding lateral deposits extended for shorter distances, had lower, more poorly defined crests that were increasingly wider in separation than the initial outlet, and progressively became more oblong rather than linear. Based on our results, we conclude that leveed channels cannot initiate from sediment-laden density currents under strictly depositional conditions. Partial confinement of these currents appears to be necessary to

  9. Experimental Investigation of an Automobile Air-Conditioning System using Integrated Brushless Direct Current Motor Rotary Compressor

    Directory of Open Access Journals (Sweden)

    Sukri M.F.

    2016-01-01

    Full Text Available The present study presents an experimental investigation on the effect of condenser air inlet temperature and dimensionless parameter of X on the performance of automobile air-conditioning (AAC system using integrated brushless direct current motor-rotary compressor and electronic expansion valve. The other components of AAC system are from original component of AAC system used for medium size passenger car. The experimental results showed that the increment of the condenser air inlet temperature and X caused an increase in condensing temperature, cooling capacity and compressor work, while decreasing the coefficient of performance (COP. Meanwhile, the evaporating temperature increase with the increment of condenser air inlet temperature, but decrease with decrement of X. In general, AAC system have to work at higher value of X in order to produce more cooling capacity, thereby increment in compressor work also occurs due to energy balance. However, at higher value of X, the COP of the system dropped due to dominant increase in compressor power, as opposed to a rise in cooling capacity. Due to this reason, the best operation of this compressor occurs at X = 4.96 for constant T5 (35ºC, or at T5 = 30ºC for constant X (4.96.

  10. Quantum-limit spectroscopy

    CERN Document Server

    Ficek, Zbigniew

    2017-01-01

    This book covers the main ideas, methods, and recent developments of quantum-limit optical spectroscopy and applications to quantum information, resolution spectroscopy, measurements beyond quantum limits, measurement of decoherence, and entanglement. Quantum-limit spectroscopy lies at the frontier of current experimental and theoretical techniques, and is one of the areas of atomic spectroscopy where the quantization of the field is essential to predict and interpret the existing experimental results. Currently, there is an increasing interest in quantum and precision spectroscopy both theoretically and experimentally, due to significant progress in trapping and cooling of single atoms and ions. This progress allows one to explore in the most intimate detail the ways in which light interacts with atoms and to measure spectral properties and quantum effects with high precision. Moreover, it allows one to perform subtle tests of quantum mechanics on the single atom and single photon scale which were hardly eve...

  11. Experimental primates and non-human primate (NHP) models of human diseases in China: current status and progress.

    Science.gov (United States)

    Zhang, Xiao-Liang; Pang, Wei; Hu, Xin-Tian; Li, Jia-Li; Yao, Yong-Gang; Zheng, Yong-Tang

    2014-11-18

    Non-human primates (NHPs) are phylogenetically close to humans, with many similarities in terms of physiology, anatomy, immunology, as well as neurology, all of which make them excellent experimental models for biomedical research. Compared with developed countries in America and Europe, China has relatively rich primate resources and has continually aimed to develop NHPs resources. Currently, China is a leading producer and a major supplier of NHPs on the international market. However, there are some deficiencies in feeding and management that have hampered China's growth in NHP research and materials. Nonetheless, China has recently established a number of primate animal models for human diseases and achieved marked scientific progress on infectious diseases, cardiovascular diseases, endocrine diseases, reproductive diseases, neurological diseases, and ophthalmic diseases, etc. Advances in these fields via NHP models will undoubtedly further promote the development of China's life sciences and pharmaceutical industry, and enhance China's position as a leader in NHP research. This review covers the current status of NHPs in China and other areas, highlighting the latest developments in disease models using NHPs, as well as outlining basic problems and proposing effective countermeasures to better utilize NHP resources and further foster NHP research in China.

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

    Directory of Open Access Journals (Sweden)

    Johan Forslund

    2015-05-01

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

  13. Reviews on Current-limiting Protection Based on PTC Materials%基于PTC材料的限流保护研究现状

    Institute of Scientific and Technical Information of China (English)

    惠飞飞; 杨锋

    2015-01-01

    Aimed at the increasing of the short circuit current, the current limiting is an effective way to achieve the short-circuit protection. To adopt PTC components in the current-limiting protection is a new method in this area, which not only can be both recoverable and reusable, but also has the great potential of application in the area of the large current breaker. This paper mainly summarizes and compares existing methods for current-limiting protection. What's more, it systematically analyzes the problems in the research on PTC and listed on the types and applications of those PTC in being. More importantly, detailed analysis is made in this paper on the feasibility for the solution related to PTC's withstand voltage as well as its large current shock. Finally, the full text and get the drafting solution for the PTC's application in current limit is summarized.%短路电流不断增大,采用限流的方式进行短路保护是一种有效的保护方式.使用PTC元件进行限流保护是一种新型的保护方式,具有可恢复性和可重复使用的特点,且对于大电流的分断具有很大的应用潜力.该文对现有限流保护技术进行总结与比对,对PTC研究存在问题进行系统分析,阐述罗列现有PTC种类以及适用用途,并对其耐压大电流冲击方案进行可行性分析.最后对其全文进行总结,给出限流应用PTC拟解决方案.

  14. Thick-shelled, grazer-protected diatoms decouple ocean carbon and silicon cycles in the iron-limited Antarctic Circumpolar Current

    NARCIS (Netherlands)

    Assmy, P.; Smetacek, V.; Klaas, C.; Henjes, J.; Strass, V.H.; Arrieta, J.M.; Bathmann, U.; Cisewski, B.; Fuchs, N.; Herndl, G.J.

    2013-01-01

    Diatoms of the iron-replete continental margins and North Atlantic are key exporters of organic carbon. In contrast, diatoms of the iron-limited Antarctic Circumpolar Current sequester silicon, but comparatively little carbon, in the underlying deep ocean and sediments. Because the Southern Ocean is

  15. Experimental and theoretical studies of a high temperature cesium-barium tacitron, with application to low voltage-high current inversion. Final report, April 1, 1993--February 28, 1994

    Energy Technology Data Exchange (ETDEWEB)

    Murray, C.S.; El-Genk, M.S.

    1994-02-01

    A low voltage/high current switch refer-red as ``Cs-Ba tacitron`` is studied for use as a dc to ac inverter in high temperature and/or ionizing radiation environments. The operational characteristics of the Cs-Ba tacitron as a switch were investigated experimentally in three modes: (a) breakdown mode, (b) I-V mode, and (c) current modulation mode. Operation parameters measured include switching frequencies up to 20 kHz, hold-off voltages up to 200 V, current densities in excess of 15 A/CM{sup 2}, switch power density of 1 kW/cm{sup 2}, and a switching efficiency in excess of 90 % at collector voltages greater than 30 V. Also, if the discharge current is circuit limited to a value below the maximum thermal emission current density, the voltage drop is constant and below 3 V.

  16. A Dual-Mode Step-up DC/DC Converter IC with Current-Limiting and EMI Reduction Techniques

    Institute of Scientific and Technical Information of China (English)

    Wan-Rone Liou; Chun-Ting Kuo; Mei-Ling Yeh; Ping-Hsing Chen; Marynelle L. Z. Rosales

    2008-01-01

    This paper presents a novel dual-mode step-up (boost) DC/DC converter. Pulse-frequency modulation (PFM) is used to improve the efficiency at light load. This converter can operate between pulse-width modulation (PWM) and pulse-frequency modulation. The converter will operate in PFM mode at light load and in PWM mode at heavy load. The maximum conversion efficiency of this converter is 96%. The conversion efficiency is greatly improved when load current is below 100 mA. Additionally, a soft-start circuit and a variable-sawtooth frequency circuit are proposed in this paper. The former is used to avoid the large switching current at the start up of the converter and the latter is utilized to reduce the EMI of the converter.

  17. Current limitations and a path forward to improve testing for the environmental assessment of endocrine active substances

    DEFF Research Database (Denmark)

    Coady, Katherine K.; Biever, Ronald C.; Denslow, Nancy D.

    issue of significant concern to for current EACS screening/testing programs involves resources in regard such as to cost, time, trained personnel, and animal use. This is especially problematic when considering the number of chemicals that some regulatory authorities need to assess. One way to address......, statistical power to detect biologically significant adverse effects, delivery and analytical measurement of test substances, availability of technical expertise, and study interpretation, including linking mechanistic and apical effects. Some of these areas can be addressed by the lessons learned and best...... screening/testing. Finally, a number of recommendations are provided for longer term research to address areas of uncertainty, including identifying potentially sensitive species for which test methods currently do not exist (e.g., invertebrates) and key endocrine pathways in addition to estrogen, androgen...

  18. Nanofabrication of Arrays of Silicon Field Emitters with Vertical Silicon Nanowire Current Limiters and Self-Aligned Gates

    Science.gov (United States)

    2016-08-19

    Akinwande Department of Electrical Engineering and Computer Science and Microsystems Technology Laboratories, Massachusetts Institute of Technology ...Cambridge, MA 02139, USA E-mail: guerrera@alum.mit.edu Received 16 September 2015, revised 2 December 2015 Accepted for publication 11 January 2016...series with the tip. Using the current voltage characteristics and with the aid of numerical device models , we estimated the tip radius of our field

  19. Experimental observation and modelling of roughness variation due to supply-limited sediment transport in uni-directional flow

    NARCIS (Netherlands)

    Tuijnder, A.P.; Ribberink, J.S.

    2012-01-01

    This paper presents a study on the relationship between supply-limited bedform formation and the hydraulic roughness of the riverbed. The results of several new sets of flume experiments with supply-limited or partial transport conditions with bimodal sediment are presented. The results show that bo

  20. Experimental observation and modelling of roughness variation due to supply-limited sediment transport in uni-directional flow

    NARCIS (Netherlands)

    Tuijnder, Arjan; Ribberink, Jan S.

    2012-01-01

    This paper presents a study on the relationship between supply-limited bedform formation and the hydraulic roughness of the riverbed. The results of several new sets of flume experiments with supply-limited or partial transport conditions with bimodal sediment are presented. The results show that