Magnetosphere dynamics during the 14 November 2012 storm inferred from TWINS, AMPERE, Van Allen Probes, and BATS-R-US-CRCM

Science.gov (United States)

Buzulukova, Natalia; Goldstein, Jerry; Fok, Mei-Ching; Glocer, Alex; Valek, Phil; McComas, David; Korth, Haje; Anderson, Brian

2018-01-01

During the 14 November 2012 geomagnetic storm, the Van Allen Probes spacecraft observed a number of sharp decreases (dropouts) in particle fluxes for ions and electrons of different energies. In this paper, we investigate the global magnetosphere dynamics and magnetosphere-ionosphere (M-I) coupling during the dropout events using multipoint measurements by Van Allen Probes, TWINS, and AMPERE together with the output of the two-way coupled global BATS-R-US-CRCM model. We find different behavior for two pairs of dropouts. For one pair, the same pattern was repeated: (1) weak nightside Region 1 and 2 Birkeland currents before and during the dropout; (2) intensification of Region 2 currents after the dropout; and (3) a particle injection detected by TWINS after the dropout. The model predicted similar behavior of Birkeland currents. TWINS low-altitude emissions demonstrated high variability during these intervals, indicating high geomagnetic activity in the near-Earth tail region. For the second pair of dropouts, the structure of both Birkeland currents and ENA emissions was relatively stable. The model also showed quasi-stationary behavior of Birkeland currents and simulated ENA emissions with gradual ring current buildup. We confirm that the first pair of dropouts was caused by large-scale motions of the OCB (open-closed boundary) during substorm activity. We show the new result that this OCB motion was associated with global changes in Birkeland (M-I coupling) currents and strong modulation of low-altitude ion precipitation. The second pair of dropouts is the result of smaller OCB disturbances not related to magnetospheric substorms. The local observations of the first pair of dropouts result from a global magnetospheric reconfiguration, which is manifested by ion injections and enhanced ion precipitation detected by TWINS and changes in the structure of Birkeland currents detected by AMPERE. This study demonstrates that multipoint measurements along with the global

Euler potentials for two layers with non-constant current densities in the ambient magnetic field aligned to the layers

Czech Academy of Sciences Publication Activity Database

Vandas, Marek; Romashets, E.

2016-01-01

Roč. 34, č. 12 (2016), s. 1165-1173 ISSN 0992-7689 R&D Projects: GA ČR(CZ) GA14-19376S Institutional support: RVO:67985815 Keywords : magnetospheric physics * scale birkeland currents * charged particles Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 1.610, year: 2016

Effect of magnetic field-aligned currents on VLF emissions in the magnetosphere

International Nuclear Information System (INIS)

Kulkarni, V.H.

1988-01-01

The dispersion relation for the electromagnetic electron cyclotron waves in the presence of magnetic field-aligned currents has been obtained. The kinetic distribution of electrons for the main body of plasma with a temperature anisotropy and a loss cone distribution have been considered. In general, it has been seen that the current moving along the direction of resonant electrons reduce the growth rate. This effect has been analysed in the case of magnetospheric plasma to suggest possible correlations between the Birkeland currents and the emissions of very low frequency (VLF) electromagnetic waves. (author). 19 refs

Relationship between Birkeland current regions, particle precipitation, and electric fields

International Nuclear Information System (INIS)

Beaujardiere, O. de la; Watermann, J.; Newell, P.; Rich, F.

1993-01-01

The authors study relationships between particle precipitation, currents, and convection, using data from DMSP observations and observations of the Sondrestrom radar. They adopt the classification of Newell et al., who defined five different classes of particle populations observed in satellite crossings of auroral regions. Observations were limited to prenoon local times. The advantage of the DMSP data is that it is part of a consistent 10 year observation mission which provides a broad replicated data set. It is difficult to specify with certainty the polar cap boundary from DMSP data alone

A high-latitude, low-latitude boundary layer model of the convection current system

International Nuclear Information System (INIS)

Siscoe, G.L.; Lotko, W.; Sonnerup, B.U.O.

1991-01-01

Observations suggest that both the high- and low-latitude boundary layers contribute to magnetospheric convection, and that their contributions are linked. In the interpretation pursued here, the high-latitude boundary layer (HBL) generates the voltage while the low-latitude boundary layer (LBL) generates the current for the part of the convection electric circuit that closes through the ionosphere. This paper gives a model that joins the high- and low-latitude boundary layers consistently with the ionospheric Ohm's law. It describes an electric circuit linking both boundary layers, the region 1 Birkeland currents, and the ionospheric Pedersen closure currents. The model works by using the convection electric field that the ionosphere receives from the HBL to determine two boundary conditions to the equations that govern viscous LBL-ionosphere coupling. The result provides the needed self-consistent coupling between the two boundary layers and fully specifies the solution for the viscous LBL-ionosphere coupling equations. The solution shows that in providing the current required by the ionospheric Ohm's law, the LBL needs only a tenth of the voltage that spans the HBL. The solution also gives the latitude profiles of the ionospheric electric field, parallel currents, and parallel potential. It predicts that the plasma in the inner part of the LBL moves sunward instead of antisunward and that, as the transpolar potential decreases below about 40 kV, reverse polarity (region 0) currents appear at the poleward border of the region 1 currents. A possible problem with the model is its prediction of a thin boundary layer (∼1000 km), whereas thicknesses inferred from satellite data tend to be greater

Numerical simulation of global formation of auroral arcs

International Nuclear Information System (INIS)

Miura, A.; Sato, T.

1980-01-01

Global simulation of auroral arcs is performed, based on the feedback theory of auroral arcs (Sato, 1978), for a three-dimensionally coupled ionosphere-magnetosphere system which includes two pairs of large-scale Birkeland currents, large-scale polar cap electric fields, and a day-night asymmetry of the electron density distribution. Simulation results have shown that auroral arcs are formed in the dark sector of the auroral oval, more preferentially in the evening sector. They usually appear in multiples with a shape elongating in the east-west direction, each arc being a couple of thousand kilometers in length and 10 to 40 km in width. A pair of small-scale, upward and downward, Birkeland currents is associated with each arc, the density of which becomes 10 to 200 μA/m 2 at 110-km height, and the intensity of the associated electrojet reaches 5 to 20 kA. Each arc is strongly polarized in the direction of the large-scale northsouth current so that the electric field inside the arc is reduced considerably from its ambient value. What controls the formation of auroral arcs (growing speed, locations, arc width, etc.) is examined in detail. For example, the arc width becomes sharper, as the bounce time of the Alfven wave decreases. The overall structure of auroras is largely dependent upon the large-scale Birkeland current, the electric field, and the electron density distribution in the auroral oval

Computer simulation of inner magnetospheric dynamics for the magnetic storm of July 29, 1977

International Nuclear Information System (INIS)

Wolf, R.A.; Harel, M.; Spiro, R.W.; Voigt, G.; Reiff, P.H.; Chen, C.

1982-01-01

We present preliminary results of applying the Rice convection model to the early main phase of the magnetic storm of July 29, 1977. The computer model self-consistently computes electric fields and currents, as well as plasma distributions and velocities, in the inner-magnetosphere/ionosphere system. In the equatorial plane, the region modeled includes geocentric distances less than about the magnetopause standoff distance. Particle loss, parallel electric fields, and neutral winds are neglected. On the basis of solar wind parameters and the AL index as input, the model predicts the injection of plasma-sheet plasma to form a substantial storm time ring current. The total strength of the model-predicted ring current agrees accurately with the observed Dst index. Comparison of the model results with electric fields and Birkeland currents measured by S3-3 shows qualitative agreement but interesting quantitative discrepancies. During this event, region 1 currents, which in standard convection theory would connect to the outer magnetosphere, are observed as low as 60 0 invariant latitude at dawn and dusk. We examine the possibility that the magnetic field might be so highly inflated that 60 0 field lines extend to the outer magnetosphere. In the model, distortion of the inner edge of the plasma sheet by the magnetospheric compression associated with the sudden commencement temporarily disturbs the normal Birkeland-current pattern. The normal tendency for the plasma sheet's inner edge to shield low L alues from the convection electric field is also temporarily disrupted. Normal Birkeland currents and shielding reassert themselves after about an hour. Time-integrated Joule heating in the model ionosphere over the first 5.5 hours of the storm main phase is about half the increase in model ring-current energy

Seasonal and Temporal Variations of Field-Aligned Currents and Ground Magnetic Deflections During Substorms

Science.gov (United States)

Forsyth, C.; Shortt, M.; Coxon, J. C.; Rae, I. J.; Freeman, M. P.; Kalmoni, N. M. E.; Jackman, C. M.; Anderson, B. J.; Milan, S. E.; Burrell, A. G.

2018-04-01

Field-aligned currents (FACs), also known as Birkeland currents, are the agents by which energy and momentum are transferred to the ionosphere from the magnetosphere and solar wind. This coupling is enhanced at substorm onset through the formation of the substorm current wedge. Using FAC data from the Active Magnetosphere and Planetary Electrodynamics Response Experiment and substorm expansion phase onsets identified using the Substorm Onsets and Phases from Indices of the Electrojet technique, we examine the Northern Hemisphere FACs in all local time sectors with respect to substorm onset and subdivided by season. Our results show that while there is a strong seasonal dependence on the underlying FACs, the increase in FACs following substorm onset only varies by 10% with season, with substorms increasing the hemispheric FACs by 420 kA on average. Over an hour prior to substorm onset, the dayside currents in the postnoon quadrant increase linearly, whereas the nightside currents show a linear increase starting 20-30 min before onset. After onset, the nightside Region 1, Region 2, and nonlocally closed currents and the SuperMAG AL (SML) index follow the Weimer (1994, https://doi.org/10.1029/93JA02721) model with the same time constants in each season. These results contrast earlier contradictory studies that indicate that substorms are either longer in the summer or decay faster in the summer. Our results imply that, on average, substorm FACs do not change with season but that their relative impact on the coupled magnetosphere-ionosphere system does due to the changes in the underlying currents.

Mechanism of parallel electric fields inferred from observations

International Nuclear Information System (INIS)

Yeh, H.; Hill, T.W.

1981-01-01

An analysis of satellite data from regions of upward Birkeland (magnetic-field-aligned) current shows that the typical magnetic-field-aligned potential drop in the auroral zone is larger than required to provide direct acceleration of magnetospheric electrons by the field-aligned electric field against the upward magnetic force to produce the observed upward Birkeland current. A model of simple electrostatic acceleration without anomalous resistivity predicts observable relations between parallel current and parallel potential drop and between energy deposition and parallel potential drop. The temperature, density, and species of the unaccelerated charge carriers are the relevant parameters of the model. Simultaneously measurements of electron precipitation and ion drift velocities on the satellites Atmosphere Explorere C and D were used to test these relations. In a steady state the divergence of ionospheric currents must be compensated by Birkeland currents. The model current-voltage relation was applied to predict the densities of the primary charge carriers (i.e., plasma sheet electrons above the acceleration region for upward currents). In cases involving thin arc structures, where the reliable estimation of the divergence of ionospheric current is difficult and the steady-state assumption may not apply, the precipitating energy flux versus voltage relation was used to predict the densities of the unaccelerated plasma sheet electrons. Within the experimental uncertainties, reasonable agreement is found between these predicted densities and those inferred directly from the simultaneous data of the Low-Energy Electron Experiment. These results are interpreted as indicating that anomalous resistivity is not important in determining the magnitude of the field-aligned potential drop in the auroral zone

Three-dimensional MHD simulation of the interaction of the solar wind with the earth's magnetosphere: The generation of field-aligned currents

International Nuclear Information System (INIS)

Ogino, T.

1986-01-01

A global computer simulation of the interaction of the solar wind with the earth's magnetosphere was executed by using a three-dimensional magnetohydrodynamic model. As a result, we were able to reproduce quasi-steady-state magnetospheric configurations and a Birkeland field-aligned current system which depend on the polarity of the z component of the interplanetary magnetic field (IMF). Twin convection cells and a dawn to dusk electric potential of 30--100 kV appeared at the equator in the magnetosphere. Four types of field-aligned currents were observed. Region 1 and 2 field-aligned currents generated for all IMF conditions were 0.6--1.0 x 10 6 A and 0.15--0.61 x 10 6 A, respectively, in the total current. Region 1 currents at high latitudes are generated from the field-aligned vorticity at the flanks through a viscous interaction and are strengthened by a twisting of open magnetic field lines in the tail region for southward IMF. On the other hand, the low-latitude region 2 currents probably are generated mainly from the inner pressure gradient of the plasma sheet. The region 1 current obtained from the simulation was in good agreement with an estimate from our theoretical analysis of the localized Alfven mode. The other two types of field-aligned currents are the dayside magnetopause currents in the dayside cusp region, which increase for northward IMF, and the dayside cusp currents for southward IMF. The cusp currents are associated with a twisting of open magnetic field lines in the magnetopause region

CURRENT TRANSFER SYSTEMS

Science.gov (United States)

Watt, D.A.

1956-07-01

A current transfer system is described for transferring current between a rotating member and a co-axial stationary member. The particular area of application for the invention is in connection with homopolar generators where a low voltage and high current are generated. The current tramsfer system of the invention comprises a rotor member and a co-axial stator member wherein one of the members is shaped to provide a circumferential surface concave in section and the other member is shaped to have a peripheral portion in close proximity to the surface, whereby a liquid metal can be stably supported between the two members when they are moving relative to one another to establish an electrical conducting path between the members.

Three-dimensional equilibria for the extended magnetotail and the generation of field-aligned current sheets

International Nuclear Information System (INIS)

Birn, J.

1989-01-01

Using the magnetotail equilibrium theory and a solution method outlined by Birn (1987), we have constructed self-consistent three-dimensional models for the quiet average magnetotail beyond about 20 R/sub E/ distance but earthward of a potential distant neutral line, which take into account the decrease of the tail flaring with distance. We find that this effect is coupled with the presence of magnetic shear and thus with field-aligned electric currents. These currents have the signature of region 1 currents, toward the Earth on the dawnside and away on the duskside, and contribute about 5 x 10 5 A to the total Birkeland current. They are strongly concentrated near the plasma sheet-lobe boundary and increase toward the flanks of the tail. Associated with the field-aligned currents and the corresponding magnetic field shear there is a bulging effect that tends to deform a circular cross section of the tail near the Earth into one that has bulges in the low-latitude boundary region. We argue that this effect may be the cause for increased interaction with the solar wind in these regions, producing interconnected fields and tailward flowing plasma on magnetospheric-like fields in the low-latitude boundary layer, and deforming this boundary region into the observed dog bone shape of the plasma sheet cross section. copyright American Geophysical Union 1989

Periodic auroral forms and geomagnetic field oscillations in the 1400 MLT region

International Nuclear Information System (INIS)

Potemra, T.A.; Vo, H.; Venkatesan, D.; Cogger, L.L.; Erlandson, R.E.; Zanetti, L.J.; Bythrow, P.F.; Anderson, B.J.

1990-01-01

The UV images obtained with the Viking satellite often show bright features which resemble beads or pearls aligned in the east-west direction between noon and 1800 MLT. Viking acquired a series of 25 UV images during a 28-min period on July 29, 1986, which showed a distinct series of periodic bright features in this region. Magnetic field and hot plasma measurements obtained by Viking confirm that the UV emissions are colocated with the field line projection of an upward-flowing region 1 Birkeland current and precipitating energetic (∼200 eV) electrons. The magnetic field and electric field measurements show transverse oscillations with a nearly constant period of about 3.5 min from 67 degree invariant latitude equatorward up to the location of the large-scale Birkeland current system near 76 degree invariant latitude. The electric field oscillations lead the magnetic field oscillations by about a quarter-period. The authors interpret the observed oscillations as standing Alfven waves driven at a frequency near the local resonance frequency by a large-scale wave in the boundary layer. They propose that the energy flux of the precipitating low-energy electrons in this afternoon region is modulated by this boundary wave and produces the periodic UV emission features. The results of this study support the view that large-scale oscillations of magnetospheric boundaries, possibly associated with the Kelvin-Helmholtz instability, can modulate currents, particles, and auroral forms

Measurement technology of RF interference current in high current system

Science.gov (United States)

Zhao, Zhihua; Li, Jianxuan; Zhang, Xiangming; Zhang, Lei

2018-06-01

Current probe is a detection method commonly used in electromagnetic compatibility. With the development of power electronics technology, the power level of power conversion devices is constantly increasing, and the power current of the electric energy conversion device in the electromagnetic launch system can reach 10kA. Current probe conventionally used in EMC (electromagnetic compatibility) detection cannot meet the test requirements on high current system due to the magnetic saturation problem. The conventional high current sensor is also not suitable for the RF (Radio Frequency) interference current measurement in high current power device due to the high noise level in the output of active amplifier. In this paper, a passive flexible current probe based on Rogowski coil and matching resistance is proposed that can withstand high current and has low noise level, to solve the measurement problems of interference current in high current power converter. And both differential mode and common mode current detection can be easily carried out with the proposed probe because of the probe's flexible structure.

Auroral arc classification scheme based on the observed arc-associated electric field pattern

International Nuclear Information System (INIS)

Marklund, G.

1983-06-01

Radar and rocket electric field observations of auroral arcs have earlier been used to identify essentially four different arc types, namely anticorrelation and correlation arcs (with, respectively, decreased and increased arc-assocaited field) and asymmetric and reversal arcs. In this paper rocket double probe and supplementary observations from the literature, obtained under various geophysical conditions, are used to organize the different arc types on a physical rather than morphological basis. This classification is based on the relative influence on the arc electric field pattern from the two current continuity mechanisms, polarisation electric fields and Birkeland currents. In this context the tangential electric field plays an essential role and it is thus important that it can be obtained with both high accuracy and resolution. In situ observations by sounding rockets are shown to be better suited for this specific task than monostatic radar observations. Depending on the dominating mechanism, estimated quantitatively for a number of arc-crossings, the different arc types have been grouped into the following main categories: Polarisation arcs, Birkeland current arcs and combination arcs. Finally the high altitude potential distributions corresponding to some of the different arc types are presented. (author)

Design of BEPCII bunch current monitor system

International Nuclear Information System (INIS)

Zhang Lei; Ma Huizhou; Yue Junhui; Lei Ge; Cao Jianshe; Ma Li

2008-01-01

BEPC II is an electron-positron collider designed to run under multi-bunches and high beam current condition. The accelerator consists of an electron ring, a positron ring and a linear injector. In order to achieve the target luminosity and implement the equal bunch charge injection, the Bunch Current Monitor (BCM) system is built on BEPC II. The BCM system consists of three parts: the front-end circuit, the bunch current acquisition system and the bucket selection system. The control software of BCM is based on VxWorks and EPICS. With the help of BCM system, the bunch current in each bucket can be monitored in the Central Control Room. The BEPC II timing system can also use the bunch current database to decide which bucket needs to refill to implement 'top-off' injection. (authors)

Current and Future Flight Operating Systems

Science.gov (United States)

Cudmore, Alan

2007-01-01

This viewgraph presentation reviews the current real time operating system (RTOS) type in use with current flight systems. A new RTOS model is described, i.e. the process model. Included is a review of the challenges of migrating from the classic RTOS to the Process Model type.

Bow Shock Generator Current Systems: MMS Observations of Possible Current Closure

Science.gov (United States)

Hamrin, M.; Gunell, H.; Lindkvist, J.; Lindqvist, P.-A.; Ergun, R. E.; Giles, B. L.

2018-01-01

We use data from the first two dayside seasons of the Magnetospheric Multiscale (MMS) mission to study current systems associated with quasi-perpendicular bow shocks of generator type. We have analyzed 154 MMS bow shock crossings near the equatorial plane. We compute the current density during the crossings and conclude that the component perpendicular to the shock normal (J⊥) is consistent with a pileup of the interplanetary magnetic field (IMF) inside the magnetosheath. For predominantly southward IMF, we observe a component Jn parallel (antiparallel) to the normal for GSM Y > 0 (MMS probing region. For IMF clock angles near 90∘, we find indications of the current system being tilted toward the north-south direction, obtaining a significant Jz component, and we suggest that the current closes off the equatorial plane at higher latitudes where the spacecraft are not probing. The observations are complicated for several reasons. For example, variations in the solar wind and the magnetospheric currents and loads affect the closure, and Jn is distributed over large regions, making it difficult to resolve inside the magnetosheath proper.

Current control system for superconducting coils of LHD

International Nuclear Information System (INIS)

Chikaraishi, H.; Yamada, S.; Inoue, T.

1996-01-01

This paper introduce a coil current control system of the LHD. The main part of this system consists of two VME based real time computers and a risc based work station which are connected by optical fiber link. In this computer system, a coil current controller for steady state operation of LHD which based on a state variable control theory is installed. Also advanced current control scheme, which are now developing for dynamic current control in phase II operation of LHD, are introduced. (author)

Sustained currents in coupled diffusive systems

International Nuclear Information System (INIS)

Larralde, Hernán; Sanders, David P

2014-01-01

Coupling two diffusive systems may give rise to a nonequilibrium stationary state (NESS) with a non-trivial persistent, circulating current. We study a simple example that is exactly soluble, consisting of random walkers with different biases towards a reflecting boundary, modelling, for example, Brownian particles with different charge states in an electric field. We obtain analytical expressions for the concentrations and currents in the NESS for this model, and exhibit the main features of the system by numerical simulation. (paper)

The Earth's magnetosphere is 165 R(sub E) long: Self-consistent currents, convection, magnetospheric structure, and processes for northward interplanetary magnetic field

Science.gov (United States)

Fedder, J. A.; Lyon, J. G.

1995-01-01

The subject of this paper is a self-consistent, magnetohydrodynamic numerical realization for the Earth's magnetosphere which is in a quasi-steady dynamic equilibrium for a due northward interplanetary magnetic field (IMF). Although a few hours of steady northward IMF are required for this asymptotic state to be set up, it should still be of considerable theoretical interest because it constitutes a 'ground state' for the solar wind-magnetosphere interaction. Moreover, particular features of this ground state magnetosphere should be observable even under less extreme solar wind conditions. Certain characteristics of this magnetosphere, namely, NBZ Birkeland currents, four-cell ionospheric convection, a relatively weak cross-polar potential, and a prominent flow boundary layer, are widely expected. Other characteristics, such as no open tail lobes, no Earth-connected magnetic flux beyond 155 R(sub E) downstream, magnetic merging in a closed topology at the cusps, and a 'tadpole' shaped magnetospheric boundary, might not be expected. In this paper, we will present the evidence for this unusual but interesting magnetospheric equilibrium. We will also discuss our present understanding of this singular state.

A New Current Drogue System for Remotely Monitoring Shelf Current Circulation

Science.gov (United States)

Klemas, V. (Principal Investigator); Davis, G.; Whelan, W.; Tornatore, G.

1975-01-01

The author has identified the following significant results. An ocean current drogue system was developed for use in the coastal zone and continental shelf region. The method features an extremely simple radiosonde device whose position is determined from a pair of cooperative shore stations. These ocean sondes follow the tradition of the atmospheric radiosonde in that they are economically disposable at the end of their mission. The system was successfully tested in a number of environments, including the North Atlantic in two winter coastal storms. Tracking to the edge of the Baltimore and Wilmington trenches was achieved. The drogue system is being used in conjunction with remote sensing aircraft and satellites to chart current circulation at ocean waste disposal sites 40 miles off Delaware's coast.

Permanent spin currents in cavity-qubit systems

Science.gov (United States)

Kulkarni, Manas; Hein, Sven M.; Kapit, Eliot; Aron, Camille

2018-02-01

In a recent experiment [P. Roushan et al., Nat. Phys. 13, 146 (2017), 10.1038/nphys3930], a spin current in an architecture of three superconducting qubits was produced during a few microseconds by creating synthetic magnetic fields. The lifetime of the current was set by the typical dissipative mechanisms that occur in those systems. We propose a scheme for the generation of permanent currents, even in the presence of such imperfections, and scalable to larger system sizes. It relies on striking a subtle balance between multiple nonequilibrium drives and the dissipation mechanisms, in order to engineer and stimulate chiral excited states which can carry current.

Statistical analysis of storm-time near-Earth current systems

Directory of Open Access Journals (Sweden)

M. W. Liemohn

2015-08-01

Full Text Available Currents from the Hot Electron and Ion Drift Integrator (HEIDI inner magnetospheric model results for all of the 90 intense storms (disturbance storm-time (Dst minimum < −100 nT from solar cycle 23 (1996–2005 are calculated, presented, and analyzed. We have categorized these currents into the various systems that exist in near-Earth space, specifically the eastward and westward symmetric ring current, the partial ring current, the banana current, and the tail current. The current results from each run set are combined by a normalized superposed epoch analysis technique that scales the timeline of each phase of each storm before summing the results. It is found that there is a systematic ordering to the current systems, with the asymmetric current systems peaking during storm main phase (tail current rising first, then the banana current, followed by the partial ring current and the symmetric current systems peaking during the early recovery phase (westward and eastward symmetric ring current having simultaneous maxima. The median and mean peak amplitudes for the current systems ranged from 1 to 3 MA, depending on the setup configuration used in HEIDI, except for the eastward symmetric ring current, for which the mean never exceeded 0.3 MA for any HEIDI setup. The self-consistent electric field description in HEIDI yielded larger tail and banana currents than the Volland–Stern electric field, while the partial and symmetric ring currents had similar peak values between the two applied electric field models.

Sizing Performance of the Newly Developed Eddy Current System

Energy Technology Data Exchange (ETDEWEB)

Cho, Chan Hee; Lee, Hee Jong; Yoo, Hyun Ju; Moon, Gyoon Young; Lee, Tae Hoon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

2013-10-15

This paper describes the comparison results of sizing performance for two systems. The KHNP developed a new eddy current testing system for the inspection of steam generator tubing in domestic nuclear power plants. The equivalency assessment of the newly developed system with the EPRI-qualified system was already carried out. In this paper, the comparisons of depth-sizing performance for the artificial flaws between two systems were performed. The results show that the newly developed system is in good agreement with the qualified system. Therefore, it is expected that the newly developed eddy current system can be used for the inspection of steam generator tubing in nuclear power plants. There are some non-destructive examination (NDE) methods for the inspection of components in nuclear power plants, such as ultrasonic, radiographic, eddy current testing, etc. The eddy current testing is widely used for the inspection of steam generator (SG) tubing because it offers a relatively low cost approach for high speed, large scale testing of metallic materials in high pressure and temperature engineering systems. The Korea Hydro and Nuclear Power Co., Ltd. (KHNP) developed an eddy current testing system for the inspection of steam generator tubing in nuclear power plants. This system includes not only hardware but software such as the frequency generator and data acquisition-analysis program. The foreign eddy current system developed by ZETEC is currently used for the inspection of steam generator tubing in domestic nuclear power plants. The equivalency assessment between two systems was already carried out in accordance with the EPRI steam generator examination guidelines.

Multi-satellite observations of magnetic fields in space plasmas

International Nuclear Information System (INIS)

Potemra, T.A.; Zanetti, L.J.; Bythrow, P.F.; Erlandson, R.E.

1987-01-01

The most common method of detecting electric currents in space has been by virtue of the magnetic perturbations they produce. A satellite can pass through a field-aligned ''Birkeland'' current and measure the in-situ magnetic perturbations. Satellite-borne magnetic field experiments may also be used to observe characteristics of resonant oscillations of the Earth's magnetic field at ULF frequencies. Examples of such measurements with magnetic field experiments on the Viking, AMPTE/CCE, and DMSP-F7 satellites will be presented. The Viking satellite, launched in February, 1986, is Sweden's first satellite and is in a polar orbit with 3.1 R/sub e/ apogee. AMPTE/CCE was launched in August, 1984, with satellites from West Germany and the United Kingdom, for the purpose of creating artificial comets in space. It is in an equatorial orbit with a 8.8 R/sub e/ apogee. The Defense Meteorological Satellite Program (DMSP)-F7 satellite was launched in October, 1983 into an 800 km circular sun-synchronous orbit in the 0830-2030 magnetic local time plane. Viking and AMPTE/CCE observed harmonic ULF pulsations when they were near the same flux tube, but separated by about 10 R/sub e/. These unique observations are used to investigate the characteristics and sources of multiple field line resonances of Alfven waves. On another occasion, Viking and DMSP-F7 observed similar magnetic perturbations at widely separated locations. The authors interpret these perturbations as due to a complicated system of large-scale stable Birkeland currents in the morning sector. This multi-satellite data set is in the early stages of exploration, but already confirms the usefulness of coordinated multi-position observations of magnetic fields in space

Current development of UAV sense and avoid system

Science.gov (United States)

Zhahir, A.; Razali, A.; Mohd Ajir, M. R.

2016-10-01

As unmanned aerial vehicles (UAVs) are now gaining high interests from civil and commercialised market, the automatic sense and avoid (SAA) system is currently one of the essential features in research spotlight of UAV. Several sensor types employed in current SAA research and technology of sensor fusion that offers a great opportunity in improving detection and tracking system are presented here. The purpose of this paper is to provide an overview of SAA system development in general, as well as the current challenges facing UAV researchers and designers.

Current system of the solar wind: results of numerical calculation

International Nuclear Information System (INIS)

Pisanko, Yu.V.

1985-01-01

Results of numerical calculations of surface current in the interplanetary current layer and steady volume current in the solar wind for heliocentric distances (1-10)Rsub(s) (Rsub(s) is the Sun radius) are given. The strength of current dependence on spatial coordinates is considered. Stationary nondissipative magnetohydrodynamic corona expansion (SNMCE) in the reference system rotating with the Sun is studied. Calculations show that three-dimensional current system of nonaxial-symmetric and nonsymmetric relatively to helioequator plane of SNMCE is more complicated than the zonal ring current around the Sun, which is the only component of the current system in spatial symmetric case

Current Monitoring System for ITER Like ICRH Antenna

International Nuclear Information System (INIS)

Argouarch, A.

2006-01-01

On TS antennas, the power transfer optimization from ICRH antenna to Plasma load is performed using feedback internal matching system. Experimental handling is required to mach the reactive impedance accordingly to the fluctuant plasma loading. As part of the development of the new ICRH prototype antenna, an additional measurement system based on Rogowski coils was developed to monitor the current distribution in antenna straps. The objective is to control module and phase of the antenna current straps with measurement provided by the coil system. Matching capacitors values, generators power and phase can also be controlled using the output of the devices, improving the real time matching control of the array. This paper details the new measurement layout, the Rogowski coil, and the whole system connected on each strap design for RF currents measurement between 40 MHz - 60 MHz for maximum amplitude of 1 kA. On the new ICRH prototype antenna, the measurement coils are coupled to the point where the strap currents are short circuited to the frame. The module and phase measurements are performed with the coils by direct magnetic induction in a vacuum and high temperature environment. Also, the Rogowski coils were characterized at low level power with vector network analyzer and the design adapted in order to obtain a controlled and reproducible gain in the desire bandwidth. The transconductive function is established with an experimental gain near -80 dB between primary circuit and inductive signal generated by the Rogowski coil. In a second step, the system with its associated electronic was qualified under high RF power. First results with high RF current (closed to 500 A at 57 MHz) match the desire Rogowski coil response. Compromises with electrical response at low power level and the coil under thermal/RF stresses were the most challenging part of the development. The overall response of the system and the current module/phase measurements are promising. A proper

LLNL current meter array--concept and system description

Energy Technology Data Exchange (ETDEWEB)

Mantrom, D.D. [Lawrence Livermore National Lab., CA (United States)

1994-11-15

A measurement capability using a horizontal array of 10 S4 current meters mounted on a stiff floating structure with 35 m aperture has been developed to support interpretation of radar imaging of surface effects associated with internal waves. This system has been fielded three times and most recently, has collected data alongside the sea-surface footprint of a land-fixed radar imaging ship-generated internal waves. The underlying need for this measurement capability is described. The specifications resulting from this need are presented and the engineering design and deployment procedures of the platform and systems that resulted are described The current meter data are multiplexed along with meteorological and system status data on board the floating platform and are telemetered to a shore station and on to a data acquisition system. The raw data are recorded, and are then processed to form space-time images of current and strain rate (a spatial derivative of the current field). Examples of raw and processed data associated with ship-generated internal waves are presented.

Direct current power delivery system and method

Science.gov (United States)

Zhang, Di; Garces, Luis Jose; Dai, Jian; Lai, Rixin

2016-09-06

A power transmission system includes a first unit for carrying out the steps of receiving high voltage direct current (HVDC) power from an HVDC power line, generating an alternating current (AC) component indicative of a status of the first unit, and adding the AC component to the HVDC power line. Further, the power transmission system includes a second unit for carrying out the steps of generating a direct current (DC) voltage to transfer the HVDC power on the HVDC power line, wherein the HVDC power line is coupled between the first unit and the second unit, detecting a presence or an absence of the added AC component in the HVDC power line, and determining the status of the first unit based on the added AC component.

System for evaluating weld quality using eddy currents

Science.gov (United States)

Todorov, Evgueni I.; Hay, Jacob

2017-12-12

Electromagnetic and eddy current techniques for fast automated real-time and near real-time inspection and monitoring systems for high production rate joining processes. An eddy current system, array and method for the fast examination of welds to detect anomalies such as missed seam (MS) and lack of penetration (LOP) the system, array and methods capable of detecting and sizing surface and slightly subsurface flaws at various orientations in connection with at least the first and second weld pass.

EDDYMULT: a computing system for solving eddy current problems in a multi-torus system

International Nuclear Information System (INIS)

Nakamura, Yukiharu; Ozeki, Takahisa

1989-03-01

A new computing system EDDYMULT based on the finite element circuit method has been developed to solve actual eddy current problems in a multi-torus system, which consists of many torus-conductors and various kinds of axisymmetric poloidal field coils. The EDDYMULT computing system can deal three-dimensionally with the modal decomposition of eddy current in a multi-torus system, the transient phenomena of eddy current distributions and the resultant magnetic field. Therefore, users can apply the computing system to the solution of the eddy current problems in a tokamak fusion device, such as the design of poloidal field coil power supplies, the mechanical stress design of the intensive electromagnetic loading on device components and the control analysis of plasma position. The present report gives a detailed description of the EDDYMULT system as an user's manual: 1) theory, 2) structure of the code system, 3) input description, 4) problem restrictions, 5) description of the subroutines, etc. (author)

A Short-Current Control Method for Constant Frequency Current-Fed Wireless Power Transfer Systems

Directory of Open Access Journals (Sweden)

Yanling Li

2017-04-01

Full Text Available Frequency drift is a serious problem in Current-Fed Wireless Power Transfer (WPT systems. When the operating frequency is drifting from the inherent Zero Voltage Switching (ZVS frequency of resonant network, large short currents will appear and damage the switches. In this paper, an inductance-dampening method is proposed to inhibit short currents and achieve constant-frequency operation. By adding a small auxiliary series inductance in the primary resonant network, short currents are greatly attenuated to a safe level. The operation principle and steady-state analysis of the system are provided. An overlapping time self-regulating circuit is designed to guarantee ZVS running. The range of auxiliary inductances is discussed and its critical value is calculated exactly. The design methodology is described and a design example is presented. Finally, a prototype is built and the experimental results verify the proposed method.

A Labview Based Leakage Current Monitoring System For HV Insulators

Directory of Open Access Journals (Sweden)

N. Mavrikakis

2015-10-01

Full Text Available In this paper, a Labview based leakage current monitoring system for High Voltage insulators is described. The system uses a general purpose DAQ system with the addition of different current sensors. The DAQ system consists of a chassis and hot-swappable modules. Through the proper design of current sensors, low cost modules operating with a suitable input range can be employed. Fully customizable software can be developed using Labview, allowing on-demand changes and incorporation of upgrades. Such a system provides a low cost alternative to specially designed equipment with the added advantage of maximum flexibility. Further, it can be modified to satisfy the specifications (technical and economical set under different scenarios. In fact, the system described in this paper has already been installed in the HV Lab of the TEI of Crete whereas a variation of it is currently in use in TALOS High Voltage Test Station.

Reduction of the heat leak in superconducting system at half-wave-rectified current mode by peltier current lead

International Nuclear Information System (INIS)

Yamaguchi, Takayuki; Ohtaki, Naohiro; Nakamura, Keiji; Yamaguchi, Satarou; Hasegawa, Yasuhiro

2002-01-01

Experiments of Peltier current lead (PCL) were performed by the way of half-wave-rectified current (HWRC) for an evaluation of the PCL system in the drive with the large-rippled current. The current ripple of the HWRC is large, and we discussed the cooling capability of the current ripple. The experimental results revealed that the temperature difference of the thermoelectric-element (TE) increased with the magnitude of the current in the PCL system, despite the large current ripple. Calorimetric measurements revealed that the PCL reduced the heat leak of 60% for the peak current 90A. We compared the PCL systems of the direct current (dc) mode and the HWRC mode. The results showed that the current dependence of the temperature difference in the HWRC mode did not match that of the dc mode, but those of the heat leak matched well. The performance of the Peltier cooling in the HWRC mode is reduced to be 2/π time of the Seebeck coefficient for the dc mode by using the time-average method. (author)

Reduction of the heat leak in superconducting system at half-wave-rectified current mode by peltier current lead

CERN Document Server

Yamaguchi, T; Nakamura, K; Yamaguchi, S; Hasegawa, Y

2002-01-01

Experiments of Peltier current lead (PCL) were performed by the way of half-wave-rectified current (HWRC) for an evaluation of the PCL system in the drive with the large-rippled current. The current ripple of the HWRC is large, and we discussed the cooling capability of the current ripple. The experimental results revealed that the temperature difference of the thermoelectric-element (TE) increased with the magnitude of the current in the PCL system, despite the large current ripple. Calorimetric measurements revealed that the PCL reduced the heat leak of 60% for the peak current 90A. We compared the PCL systems of the direct current (dc) mode and the HWRC mode. The results showed that the current dependence of the temperature difference in the HWRC mode did not match that of the dc mode, but those of the heat leak matched well. The performance of the Peltier cooling in the HWRC mode is reduced to be 2/pi time of the Seebeck coefficient for the dc mode by using the time-average method. (author)

Rip current monitoring using GPS buoy system

Science.gov (United States)

Song, DongSeob; Kim, InHo; Kang, DongSoo

2014-05-01

The occurrence of rip current in the Haeundae beach, which is one of the most famous beaches in South Korea, has been threatening beach-goers security in summer season annually. Many coastal scientists have been investigating rip currents by using field observations and measurements, laboratory measurements and wave tank experiments, and computer and numerical modeling. Rip current velocity is intermittent and may rapidly increase within minutes due to larger incoming wave groups or nearshore circulation instabilities. It is important to understand that changes in rip current velocity occur in response to changes in incoming wave height and period as well as changes in water level. GPS buoys have been used to acquire sea level change data, atmospheric parameters and other oceanic variables in sea for the purposes of vertical datum determination, tide correction, radar altimeter calibration, ocean environment and marine pollution monitoring. Therefore, we adopted GPS buoy system for an experiment which is to investigate rip current velocity; it is sporadic and may quickly upsurge within minutes due to larger arriving wave groups or nearshore flow uncertainties. In this study, for high accurate positioning of buy equipment, a Satellite Based Argumentation System DGPS data logger was deployed to investigate within floating object, and it can be acquired three-dimensional coordinate or geodetic position of buoy with continuous NMEA-0183 protocol during 24 hours. The wave height measured by in-situ hydrometer in a cross-shore array clearly increased before and after occurrence of rip current, and wave period also was lengthened around an event. These results show that wave height and period correlate reasonably well with long-shore current interaction in the Haeundae beach. Additionally, current meter data and GPS buoy data showed that rip current velocities, about 0.2 m/s, may become dangerously strong under specific conditions. Acknowledgement This research was

Review of Current Nuclear Vacuum System Technologies

International Nuclear Information System (INIS)

Carroll, M.; McCracken, J.; Shope, T.

2003-01-01

Nearly all industrial operations generate unwanted dust, particulate matter, and/or liquid wastes. Waste dust and particulates can be readily tracked to other work locations, and airborne particulates can be spread through ventilation systems to all locations within a building, and even vented outside the building - a serious concern for processes involving hazardous, radioactive, or nuclear materials. Several varieties of vacuum systems have been proposed and/or are commercially available for clean up of both solid and liquid hazardous and nuclear materials. A review of current technologies highlights both the advantages and disadvantages of the various systems, and demonstrates the need for a system designed to address issues specific to hazardous and nuclear material cleanup. A review of previous and current hazardous/nuclear material cleanup technologies is presented. From simple conventional vacuums modified for use in industrial operations, to systems specifically engineered for such purposes, the advantages and disadvantages are examined in light of the following criteria: minimal worker exposure; minimal secondary waste generation;reduced equipment maintenance and consumable parts; simplicity of design, yet fully compatible with all waste types; and ease of use. The work effort reviews past, existing and proposed technologies in light of such considerations. Accomplishments of selected systems are presented, including identified areas where technological improvements could be suggested

Energy Current Cumulants in One-Dimensional Systems in Equilibrium

Science.gov (United States)

Dhar, Abhishek; Saito, Keiji; Roy, Anjan

2018-06-01

A recent theory based on fluctuating hydrodynamics predicts that one-dimensional interacting systems with particle, momentum, and energy conservation exhibit anomalous transport that falls into two main universality classes. The classification is based on behavior of equilibrium dynamical correlations of the conserved quantities. One class is characterized by sound modes with Kardar-Parisi-Zhang scaling, while the second class has diffusive sound modes. The heat mode follows Lévy statistics, with different exponents for the two classes. Here we consider heat current fluctuations in two specific systems, which are expected to be in the above two universality classes, namely, a hard particle gas with Hamiltonian dynamics and a harmonic chain with momentum conserving stochastic dynamics. Numerical simulations show completely different system-size dependence of current cumulants in these two systems. We explain this numerical observation using a phenomenological model of Lévy walkers with inputs from fluctuating hydrodynamics. This consistently explains the system-size dependence of heat current fluctuations. For the latter system, we derive the cumulant-generating function from a more microscopic theory, which also gives the same system-size dependence of cumulants.

Automatic control system for measuring currents produced by ionization chambers

International Nuclear Information System (INIS)

Brancaccio, Franco

2002-01-01

Ionization Chambers in current mode operation are usually used in Nuclear Metrology. Activity measurements are quickly performed by Ionization Chambers, with very good precision. For this purpose measurements of very low ionization currents, carried out by high quality instrumentation, are required. Usually, electrometers perform the current integration method under command of signals from an automation system, in order to reduce the measurement uncertainties. Among the measurement systems at the Laboratorio de Metrologia Nuclear (LMN) of IPEN, there are two ionization chamber systems. In the present work, an automation system developed for current integration measurements is described. This automation system is composed by software (graphic interface and control) and an electronic module connected to a microcomputer, by means of a commercial data acquisition card. Several test measurements were performed in order to determine the intrinsic uncertainty, linearity and stability of the system. Using calibrated radioactive solutions, the IG12/A20 chamber calibration factors for 18 F and 153 Sm were obtained, making possible to determine activities of these radionuclides. (author)

Viking satellite program - preliminary results from the APL Magnetic Field Experiment

International Nuclear Information System (INIS)

Potemra, T.A.; Zanetti, L.J.; Erlandson, R.E.; Gustafsson, G.; Acuna, M.H.; NASA, Goddard Space Flight Center, Greenbelt, MD)

1986-01-01

Sweden's Viking satellite, launched in February 1986, has been conducting plasma process observations in the earth magnetosphere and auroral regions; the U.S.-supplied APL Magnetic Field Experiment aboard Viking is used to determine field-aligned Birkeland current characteristics in previously unsampled regions of near-earth space. The Magnetic Field Experiment has an equivalent spatial resolution of 12 m in the auroral ionosphere when making measurements near apogee. The purposes of Viking's other instruments and their relationship to the Magnetic Field Experiment are discussed

The role of the ionosphere in coupling upstream ULF wave power into the dayside magnetosphere

International Nuclear Information System (INIS)

Engebretson, M.J.; Cahill, L.J. Jr.; Arnoldy, R.L.; Anderson, B.J.; Rosenberg, T.J.; Carpenter, D.L.; Inan, U.S.; Eather, R.H.

1991-01-01

A series of recent studies of Pc 3 magnetic pulsations in the dayside outer magnetosphere has given new insights into the possible mechanisms of entry of ULF wave power into the magnetosphere from a bow shock related upstream source. In this paper, the authors first review many of these new observational results by presenting a comparison of data from two 10-hour intervals on successive days in April 1986 and then present a possible model for transmission of pulsation signals from the magnetosheath into the dayside magnetosphere. Simultaneous multi-instrument observations at South Pole Station, located below the cusp/cleft ionosphere near local noon, magnetic field observations by the AMPTE CCE satellite in the dayside outer magnetosphere, and upstream magnetic field observations by the IMP 8 satellite show clear interplanetary magnetic field field magnitude control of dayside resonant harmonic pulsations and band-limited very high latitude pulsations, as well as pulsation-modulated precipitation of what appear to be magnetosheath/boundary layer electrons. They believe that this modulated precipitation may be responsible for the propagation of upstream wave power in the Pc 3 frequency band into the high-latitude ionosphere, from whence it may be transported throughout the dayside outer magnetosphere by means of an ionospheric transistor. In this model, modulations in ionospheric conductivity caused by cusp/cleft precipitation cause varying ionospheric currents with frequency spectra determined by the upstream waves; these modulations will be superimposed on the Birkeland currents, which close via these ionospheric currents. Modulated region 2 Birkeland currents will in turn provide a narrow-band source of wave energy to a wide range of dayside local times in the outer magnetosphere

A statistical study of magnetic field magnitude changes during substorms in the near earth tail

Science.gov (United States)

Lopez, R. E.; Lui, A. T. Y.; Mcentire, R. W.; Potemra, T. A.; Krimigis, S. M.

1990-01-01

Using AMPTE/CCE data taken in 1985 and 1986 when the CCE apogee (8.8 earth radii) was within 4.5 hours of midnight, 167 injection events in the near-earth magnetotail have been cataloged. These events are exactly or nearly dispersionless on a 72-sec time scale from 25 keV to 285 keV. The changes in the field magnitude are found to be consistent with the expected effects of the diversion/disruption of the cross-tail current during a substorm, and the latitudinal position of the current sheet is highly variable within the orbit of CCE. The local time variation of the magnetic-field changes implies that the substorm current wedge is composed of longitudinally broad Birkeland currents.

Evaluation of Current Controllers for Distributed Power Generation Systems

DEFF Research Database (Denmark)

Timbus, Adrian; Liserre, Marco; Teodorescu, Remus

2009-01-01

This paper discusses the evaluation of different current controllers employed for grid-connected distributed power generation systems having variable input power, such as wind turbines and photovoltaic systems. The focus is mainly set on linear controllers such as proportional-integral, proportio......This paper discusses the evaluation of different current controllers employed for grid-connected distributed power generation systems having variable input power, such as wind turbines and photovoltaic systems. The focus is mainly set on linear controllers such as proportional......-integral, proportional-resonant, and deadbeat (DB) controllers. Additionally, an improved DB controller robust against grid impedance variation is also presented. Since the paper discusses the implementation of these controllers for grid-connected applications, their evaluation is made in three operating conditions....... First, in steady-state conditions, the contribution of controllers to the total harmonic distortion of the grid current is pursued. Further on, the behavior of controllers in the case of transient conditions like input power variations and grid voltage faults is also examined. Experimental results...

The art of mapping the magnetosphere

International Nuclear Information System (INIS)

Stern, D.P.

1994-01-01

A comprehensive review is presented of the mathematical methods used to represent magnetic fields in the Earth's magnetosphere, of the way existing data-based models use these methods and of the associated problems and concepts. The magnetic field has five main components: the internal field, the magnetopause, the ring current, the tail and Birkeland currents. Methods of representing separately each of these are discussed, as is the deformation of magnetic fields; Appendix B traces the connection between deformations and the Cauchy integral. A summary section lists the uses of data-based models and their likely evolution, and Appendix A supplements the text with a set of problems. 55 refs., 20 figs

Automatic system for ionization chamber current measurements

International Nuclear Information System (INIS)

Brancaccio, Franco; Dias, Mauro S.; Koskinas, Marina F.

2004-01-01

The present work describes an automatic system developed for current integration measurements at the Laboratorio de Metrologia Nuclear of Instituto de Pesquisas Energeticas e Nucleares. This system includes software (graphic user interface and control) and a module connected to a microcomputer, by means of a commercial data acquisition card. Measurements were performed in order to check the performance and for validating the proposed design

EIA systems in Nigeria: evolution, current practice and shortcomings

International Nuclear Information System (INIS)

Ogunba, Olusegun A.

2004-01-01

Amidst mounting criticism of Environmental Impact Assessments (EIAs) carried out in Nigeria under the three independent EIA systems--the EIA Decree 86 (1992), the Town and Country Planning Decree 88 (1992) and the Petroleum Act (1969)--the paper traces the evolution of Nigeria's systems and appraises current practice and shortcomings. The path of development of the systems was traced within the framework of Gibson's model of EIA evolution [Impact Assess. Proj. Apprais., 20 (3) 2002, 151-159], while current practice and shortcomings were explored in random interview surveys of consultant firms, approval authorities and the academia. It was seen that Gibson's four-stage model is not exactly representative of the Nigerian situation, and a more appropriate six-stage model was developed. It was also established that the current practices of the three EIA systems were at different stages of evolution: one of the EIA schemes (the Town and Country Planning Decree) has not evolved satisfactorily, while the other two EIA systems have produced intricate legislations and guidelines, but fall short of first-rate practice. The other discovery was that the simultaneous use of three independent systems creates unnecessary duplication of EIA preparation with considerable time and money costs. The paper advises that Nigeria can make substantial progress along the evolutionary path through a correction of observed system shortcomings and a merger of the three systems

Smart wearable systems: current status and future challenges.

Science.gov (United States)

Chan, Marie; Estève, Daniel; Fourniols, Jean-Yves; Escriba, Christophe; Campo, Eric

2012-11-01

Extensive efforts have been made in both academia and industry in the research and development of smart wearable systems (SWS) for health monitoring (HM). Primarily influenced by skyrocketing healthcare costs and supported by recent technological advances in micro- and nanotechnologies, miniaturisation of sensors, and smart fabrics, the continuous advances in SWS will progressively change the landscape of healthcare by allowing individual management and continuous monitoring of a patient's health status. Consisting of various components and devices, ranging from sensors and actuators to multimedia devices, these systems support complex healthcare applications and enable low-cost wearable, non-invasive alternatives for continuous 24-h monitoring of health, activity, mobility, and mental status, both indoors and outdoors. Our objective has been to examine the current research in wearable to serve as references for researchers and provide perspectives for future research. Herein, we review the current research and development of and the challenges facing SWS for HM, focusing on multi-parameter physiological sensor systems and activity and mobility measurement system designs that reliably measure mobility or vital signs and integrate real-time decision support processing for disease prevention, symptom detection, and diagnosis. For this literature review, we have chosen specific selection criteria to include papers in which wearable systems or devices are covered. We describe the state of the art in SWS and provide a survey of recent implementations of wearable health-care systems. We describe current issues, challenges, and prospects of SWS. We conclude by identifying the future challenges facing SWS for HM. Copyright © 2012 Elsevier B.V. All rights reserved.

The jet 10-MW lower hybrid current drive system

International Nuclear Information System (INIS)

Gormezano, C.; Bosia, G.; Brinkschulte, H.; David, C.; Dobbing, J.A.; Kaye, A.S.; Jacquinot, J.; Lloyd, B.; Knowlton, S.; Moreau, D.

1987-01-01

A Lower Hybrid system to control the plasma current profile is being prepared so that a higher central electron temperature can be obtained. The proposed system is designed to launch 10 MW of power at f = 3.7 GHz through a single port in JET, producing between 1 and 2 MA of RF driven current at an average density of 5 x 10 19 m -3 . Current drive efficiency is maximized by using a low value of the parallel wave number spectrum (N// - 1.3 - 2.3). The final launcher will be made of 48 multijunctions fed by 24 klystrons with the proper phasing. Dynamic matching of the launcher will be optimized by moving the launcher in real time during the pulse. A first stage (2 MW) is presently under construction. The full system is being designed to be in operation in 1990

Experience of superconducting current feeders system of SST-1

International Nuclear Information System (INIS)

Gupta, N.C.; Garg, A.; Sonara, D.

2014-01-01

The superconducting current feeder system for SST-1 which has been installed and commissioned recently along with SST-1, felicitates to energize the SST-1. The CFS consists of ten pairs of 10,000 Ampere (A) rating helium vapor cooled conventional current leads, interconnecting Cu-SC joints, three numbers of cryo-compatible SC feeders ducts, current leads assembly chamber, hydraulic network and three numbers of joint boxes operated at different current rating to charge Toroidal Field and Poloidal Field coils separately. During the last three campaigns, it was possible to achieve a controlled cool down up to 4 K and showed its rated operational performance. Actively cooled liquid nitrogen shield showed temperature profile in the temperature range of 80-85K and the whole system was evacuated up to 6x10 -6 mbar. The measured LHe consumption rates from TF VCCL were 0.3 g/s and 0.35 g/s at zero current and 1 kA respectively. (author)

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

Science.gov (United States)

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

2017-08-29

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

Medical Robots: Current Systems and Research Directions

Directory of Open Access Journals (Sweden)

Ryan A. Beasley

2012-01-01

Full Text Available First used medically in 1985, robots now make an impact in laparoscopy, neurosurgery, orthopedic surgery, emergency response, and various other medical disciplines. This paper provides a review of medical robot history and surveys the capabilities of current medical robot systems, primarily focusing on commercially available systems while covering a few prominent research projects. By examining robotic systems across time and disciplines, trends are discernible that imply future capabilities of medical robots, for example, increased usage of intraoperative images, improved robot arm design, and haptic feedback to guide the surgeon.

Development and evaluation of an automated system for testing current meters

Directory of Open Access Journals (Sweden)

Ezequiel Saretta

2016-02-01

Full Text Available ABSTRACT Current meters are equipment widely used for estimating flow velocity in rivers and streams. Periodic calibrations of current meters are important to ensure the quality of measurements, but the required testing facilities are complex and only available in a few institutions. However, advances in electronics and automation may contribute to developing simple and reliable calibration systems. Thus, this study aimed to develop an automated system for testing current meters, which consisted of a trapezoidal channel, a step motor, a tow car and a management system, composed of a supervisory application and microprocessed modules to control the motor and the data acquisition. Evaluations of the displacement velocity showed that it matched the reference value up to 1.85 m s-1 for a vertical-axis current meter and 2.3 m s-1 for a horizontal-axis one. The developed system showed reliability during tests, for both current meter movement and data acquisition. The management of the system based on the developed modules and the supervisory application improved its user interface, turning all the procedure into a simple task.

A Four Channel Beam Current Monitor Data Acquisition System Using Embedded Processors

Energy Technology Data Exchange (ETDEWEB)

Wheat, Jr., Robert Mitchell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dalmas, Dale A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Dale, Gregory E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

2015-08-11

Data acquisition from multiple beam current monitors is required for electron accelerator production of Mo-99. A two channel system capable of recording data from two beam current monitors has been developed, is currently in use, and is discussed below. The development of a cost-effective method of extending this system to more than two channels and integrating of these measurements into an accelerator control system is the main focus of this report. Data from these current monitors is digitized, processed, and stored by a digital data acquisition system. Limitations and drawbacks with the currently deployed digital data acquisition system have been identified as have been potential solutions, or at least improvements, to these problems. This report will discuss and document the efforts we've made in improving the flexibility and lowering the cost of the data acquisition system while maintaining the minimum requirements.

An image-guided transcranial direct current stimulation system: a pilot phantom study

International Nuclear Information System (INIS)

Jung, Young-Jin; Kim, Jung-Hoon; Kim, Daejeong; Im, Chang-Hwan

2013-01-01

In this study, an image-guided transcranial direct current stimulation (IG-tDCS) system that can deliver an increased stimulation current to a target brain area without the need to adjust the location of an active electrode was implemented. This IG-tDCS system was based on the array-type tDCS concept, which was validated through computer simulations in a previous study. Unlike a previous study, the present IG-tDCS system adopts a single reference electrode and an active electrode array consisting of 16 (4 × 4) sub-electrodes. The proposed IG-tDCS system is capable of shaping current flow inside the human head by controlling the input currents of the arrayed electrodes. Once a target brain area has been selected, the optimal injection current of each arrayed sub-electrode is evaluated automatically using a genetic algorithm in order to deliver the maximum available current to the target area. The operation of our pilot system was confirmed through a simple phantom experiment. (paper)

Odd-parity currents induced by dynamic deformations in graphene-like systems

International Nuclear Information System (INIS)

Zhang, Kai; Zhang, Erhu; Chen, Huawei; Zhang, Shengli

2016-01-01

Reduced (3  +  1)-dimensional Dirac systems with inter-pseudo-spin and inter-valley scattering are employed to investigate current responses to (chiral) gauge fields in graphene-like systems. From (chiral) current—(chiral) current correlation functions, we derive the current responses. Except for electric currents induced by external gauge fields, we find the inter-valley scattering can break the topological nature of odd-parity currents. Given the proper conditions, this property can help us realize valley-polarized electric currents. Through the dynamic deformations generating the chiral gauge fields, we find the vortex-like currents while their profiles can be tuned by superposition of some deformations. In particular, we find a more manageable approach to realize the topological electric current by choosing a linear dynamic deformation. (paper)

System and method for quench and over-current protection of superconductor

Science.gov (United States)

Huang, Xianrui; Laskaris, Evangelos Trifon; Sivasubramaniam, Kiruba Haran; Bray, James William; Ryan, David Thomas; Fogarty, James Michael; Steinbach, Albert Eugene

2005-05-31

A system and method for protecting a superconductor. The system may comprise a current sensor operable to detect a current flowing through the superconductor. The system may comprise a coolant temperature sensor operable to detect the temperature of a cryogenic coolant used to cool the superconductor to a superconductive state. The control circuit is operable to estimate the superconductor temperature based on the current flow and the coolant temperature. The system may also be operable to compare the estimated superconductor temperature to at least one threshold temperature and to initiate a corrective action when the superconductor temperature exceeds the at least one threshold temperature.

Output Current Ripple Reduction Algorithms for Home Energy Storage Systems

Directory of Open Access Journals (Sweden)

Jin-Hyuk Park

2013-10-01

Full Text Available This paper proposes an output current ripple reduction algorithm using a proportional-integral (PI controller for an energy storage system (ESS. In single-phase systems, the DC/AC inverter has a second-order harmonic at twice the grid frequency of a DC-link voltage caused by pulsation of the DC-link voltage. The output current of a DC/DC converter has a ripple component because of the ripple of the DC-link voltage. The second-order harmonic adversely affects the battery lifetime. The proposed algorithm has an advantage of reducing the second-order harmonic of the output current in the variable frequency system. The proposed algorithm is verified from the PSIM simulation and experiment with the 3 kW ESS model.

Determination of plasma spot current and arc discharge plasma current on the system of plasma cathode electron sources using Rogowski coil technique

International Nuclear Information System (INIS)

Wirjoadi; Bambang Siswanto; Lely Susita RM; Agus Purwadi; Sudjatmoko

2015-01-01

It has been done the function test experiments of ignitor electrode system and the plasma generator electrode system to determine the current spot plasma and arc discharge plasma current with Rogowski coil technique. Ignitor electrode system that gets power supply from IDPS system can generate the plasma spot current of 11.68 ampere to the pulse width of about 33 μs, this value is greater than the design probably because of electronic components used in the IDPS system was not as planned. For the plasma generator electrode system that gets power from ADPS system capable of producing an arc discharge plasma current around 103.15 amperes with a pulse width of about 96 μs, and this value as planned. Based on the value of the arc discharge plasma current can be determined plasma electron density, which is about 10.12 10"1"9 electrons/m"3, and with this electron density value, an ignitor electrode system and a plasma generator system is quite good if used as a plasma cathode electron source system. (author)

Study on pulsed current cathodic protection in a simulated system

Energy Technology Data Exchange (ETDEWEB)

Yan, Milin; Li, Helin [Xi' an Jiao Tong Universitiy (China)]|[Tubular Goods Research Center of China National Petroleum Corp. (China); Qiu, Yubing; Guo, Xingpeng [Hua Zhong University of Science and Techonology (China)

2004-07-01

The pulsed current cathodic protection (PCCP) is a new cathodic protection (CP) technology and shows more advantages over the conventional DC cathodic protection (DCCP) in oil well casing system. However, little information about PCCP is reported. In this research, a simulated CP system was set up in a pool of 3.5 m x 2.0 m x 3.0 m size, in which the effects of the square wave pulsed current (SWPC) parameters (amplitude: IA, frequency: f, duty cycle: P), auxiliary anode distance (d) and media conductivity ({mu}) on the cathodic potential (E) distribution were studied, and the protection effects of PCCP and DCCP were compared. The results show that with increase of the square wave parameters (IA, f, P), the E distribution becomes more negative and the effects of each current parameter are relate closely to the cathode polarizing state. Only with suitable square wave parameters can the whole cathode be effectively protected. With increase of d and {mu}, the E distribution becomes more uniform. Compared with DCCP system, PCCP system has much more uniform E distribution, costs less average current, and gains much better protection effects. Further, the mechanism of PCCP was analyzed. (authors)

Cool Down Experiences with the SST-1 Helium Cryogenics System before and after Current Feeders System Modification

Science.gov (United States)

Patel, R.; Panchal, P.; Panchal, R.; Tank, J.; Mahesuriya, G.; Sonara, D.; Srikanth, G. L. N.; Garg, A.; Bairagi, N.; Christian, D.; Patel, K.; Shah, P.; Nimavat, H.; Sharma, R.; Patel, J. C.; Gupta, N. C.; Prasad, U.; Sharma, A. N.; Tanna, V. L.; Pradhan, S.

The SST-1 machine comprises a superconducting magnet system (SCMS), which includes TF and PF magnets. In order to charge the SCMS, we need superconducting current feeders consisting of SC feeders and vapor cooled current leads (VCCLs). We have installed all 10 (+/-) pairs of VCCLs for the TF and PF systems. While conducting initial engineering validation of the SST-1 machine, our prime objective was to produce circular plasma using only the TF system. During the SST-1 campaign I to VI, we have to stop the PF magnets cooling in order to get the cryo- stable conditions for current charging of the TF magnets system. In that case, the cooling of the PF current leads is not essential. It has been also observed that after aborting the PF system cooling, there was a limited experimental window of TF operation. Therefore, in the recent SST-1 campaign-VII, we removed the PF current leads (9 pairs) and kept only single (+/-) pair of the 10,000 A rated VCCLs to realize the charging of the TF system for the extended window of operation. We have observed a better cryogenic stability in the TF magnets after modifications in the CFS. In this paper, we report the comparison of the cool down performance for the SST-1 machine operation before and after modifications of the current feeders system.

On geomagnetically-induced currents in the Finnish 400 kV power system by an auroral electrojet current

International Nuclear Information System (INIS)

Pirjola, R.; Viljanen, A.

1989-01-01

The auroral electrojet current flowing in the ionosphere is modeled by a horizontal east-west line current of infinite length. The earth is described by a simple two-layer model. An expression for the earth-surface electric field, which is thus connected with a geomagnetic disturbance in and near the auroral zone, is given. This electric field is considered as external from the viewpoint of the Finnish 400 kV power system, and the resulting geomagnetically-induced currents (GICs) in the system are computed. In the north, i.e. near the electrojet, GICs may have values even in the order of hundreds of amperes. A comparison to GICs produced by an equivalent spatially-constant external electric field is demonstrated. Sometimes the location of the electrojet is further south. This possibility is studied by letting the line current have several different locations above the Finnish power grid

Stray current interaction in the system of two extensive underground conductors

International Nuclear Information System (INIS)

Machczynski, W.

1993-01-01

The important problem, technically, is to evaluate the harmful effects that an electrified railway has on nearby earth-return circuits (cables, pipelines). This paper considers the effects of a DC-electrified railway system on two extensive metal conductors buried in parallel in the vicinity of the tracks. The interaction between currents flowing in both underground conductors is taken into account, whereas the reaction of the conductors' currents on the track current is disregarded. The analysis given is applicable to any DC railway system in which tracks may be represented by a single earth return circuit with current energization. It is assumed in the paper that the system considered is linear and that the earth is homogeneous. The technical application of the method is illustrated by an example of computer simulation

Current limiter circuit system

Science.gov (United States)

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.

Evolution of the plasma universe: I. Double radio galaxies, quasars, and extragalactic jets

International Nuclear Information System (INIS)

Peratt, A.L.

1986-01-01

Cosmic plasma physics and our concept of the universe is in a state of rapid revision. This change started with in-situ measurements of plasmas in Earth's ionosphere, cometary atmospheres, and planetary magnetospheres; the translation of knowledge from laboratory experiments to astrophysical phenomena; discoveries of helical and filamentary plasma structures in the Galaxy and double radio sources; and the particle simulation of plasmas not accessible to in-situ measurement. Because of these, Birkeland (field-aligned) currents, double layers, and magnetic-field-aligned electric fields are now known to be far more important to the evolution of space plasma, including the acceleration of charged particles to high energies, than previously thought. This paper and its sequel investigate the observational evidence for a plasma universe threaded by Birkeland currents or filaments. This model of the universe was inspired by the advent of three-dimensional fully electromagnetic particle simulations and their application to the study of laboratory z pinches. This study resulted in totally unexpected phenomena in the data post-processed from the simulation particle, field, and history dumps. In particular, when the simulation parameters were scaled to galactic dimensions, the interaction between pinched filaments led to synchrotron radiation whose emission properties were found to share the following characteristics with double radio galaxies and quasars: power magnitude, isophotal morphology, spectra, brightness along source, polarization, and jets. The evolution of these pinched synchrotron emitting plasmas to elliptical, peculiar, and spiral galaxies by continuing the simulation run is addressed in a sequel paper

Nonequilibrium Microscopic Distribution of Thermal Current in Particle Systems

KAUST Repository

Yukawa, Satoshi

2009-02-15

A nonequilibrium distribution function of microscopic thermal current is studied by a direct numerical simulation in a thermal conducting steady state of particle systems. Two characteristic temperatures of the thermal current are investigated on the basis of the distribution. It is confirmed that the temperature depends on the current direction; Parallel temperature to the heat-flux is higher than antiparallel one. The difference between the parallel temperature and the antiparallel one is proportional to a macroscopic temperature gradient. ©2009 The Physical Society of Japan.

Nonequilibrium Microscopic Distribution of Thermal Current in Particle Systems

KAUST Repository

Yukawa, Satoshi; Shimada, Takashi; Ogushi, Fumiko; Ito, Nobuyasu

2009-01-01

A nonequilibrium distribution function of microscopic thermal current is studied by a direct numerical simulation in a thermal conducting steady state of particle systems. Two characteristic temperatures of the thermal current are investigated on the basis of the distribution. It is confirmed that the temperature depends on the current direction; Parallel temperature to the heat-flux is higher than antiparallel one. The difference between the parallel temperature and the antiparallel one is proportional to a macroscopic temperature gradient. ©2009 The Physical Society of Japan.

Arrester Resistive Current Measuring System Based on Heterogeneous Network

Science.gov (United States)

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

2018-03-01

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

A partial Hamiltonian approach for current value Hamiltonian systems

Science.gov (United States)

Naz, R.; Mahomed, F. M.; Chaudhry, Azam

2014-10-01

We develop a partial Hamiltonian framework to obtain reductions and closed-form solutions via first integrals of current value Hamiltonian systems of ordinary differential equations (ODEs). The approach is algorithmic and applies to many state and costate variables of the current value Hamiltonian. However, we apply the method to models with one control, one state and one costate variable to illustrate its effectiveness. The current value Hamiltonian systems arise in economic growth theory and other economic models. We explain our approach with the help of a simple illustrative example and then apply it to two widely used economic growth models: the Ramsey model with a constant relative risk aversion (CRRA) utility function and Cobb Douglas technology and a one-sector AK model of endogenous growth are considered. We show that our newly developed systematic approach can be used to deduce results given in the literature and also to find new solutions.

Modeling, Simulation, and Experiment of Switched Reluctance Ocean Current Generator System

Directory of Open Access Journals (Sweden)

Hao Chen

2013-01-01

Full Text Available This paper presents nonlinear simulation model of switched reluctance (SR ocean current generator system on MATLAB/SIMULINK with describing the structure of generator system. The developed model is made up of main model, rotor position calculation module, controller module, gate module, power converter module, phase windings module, flux-linkage module, torque module, and power calculation module. The magnetization curves obtained by two-dimensional finite-element electromagnetic field calculation and the conjugated magnetic energy graphics obtained from the three-dimensional graphics of flux linkage are stored in the “Lookup Table” modules on MATLAB/SIMULINK. The hardware of the developed three-phase 12/8 structure SR ocean current generator system prototype with the experimental platform is presented. The simulation of the prototype is performed by the developed models, and the experiments have been carried out under the same condition with different output power, turn-off angle, and rotor speed. The simulated phase current waveforms agree well with the tested phase current waveforms experimentally. The simulated output voltage curves agree well with the tested output voltage curves experimentally. It is shown that the developed nonlinear simulation model of the three-phase 12/8 structure SR ocean current generator system is valid.

Active control system upgrade design for lower hybrid current drive system on Alcator C-Mod

Energy Technology Data Exchange (ETDEWEB)

Kanojia, A.D., E-mail: akanojia@mit.edu [Massachusetts Institute of Technology Plasma Science and Fusion Center, Cambridge, MA (United States); Wallace, G.M.; Terry, D.R.; Stillerman, J.A.; Burke, W.M.; MacGibbon, P.A.; Johnson, D.K. [Massachusetts Institute of Technology Plasma Science and Fusion Center, Cambridge, MA (United States)

2012-12-15

Highlights: Black-Right-Pointing-Pointer Initial tests of the Hittite microwave components show good or better control of phase and amplitude when compared to the vector modulators used in the current system. Black-Right-Pointing-Pointer With an analog based control component system the system complexity is dramatically reduced. Black-Right-Pointing-Pointer Historically, D-tAcq hardware/software has performed more reliably on DPCS and FFT controllers than the current lower hybrid control system Black-Right-Pointing-Pointer Cost and lead time of the Hittite microwave components is significantly small compared to vector modulators. - Abstract: As a part of the scheduled expansion of the Alcator C-Mod lower hybrid current drive (LHCD) system from 12 to 16 klystrons to accommodate installation of a second LH antenna, the active control system (ACS) is being redesigned to accommodate the additional klystrons. Digitizers and output modules will be cPCI modules provided by D-tAcq Solutions. The real-time application will run on a standard PC server running Linux. Initially, the new ACS system will be designed to control 8 klystrons on the second LH antenna and the existing ACS will control the remaining 8 klystrons on the existing LH antenna. Experience gained operating the existing LHCD system has given us insight into the design of a more robust, compact, efficient and simple system for the new ACS. The design upgrade will be patterned on the digital plasma control system (DPCS [1]) in use on C-Mod.

System and method for bearing fault detection using stator current noise cancellation

Science.gov (United States)

Zhou, Wei; Lu, Bin; Habetler, Thomas G.; Harley, Ronald G.; Theisen, Peter J.

2010-08-17

A system and method for detecting incipient mechanical motor faults by way of current noise cancellation is disclosed. The system includes a controller configured to detect indicia of incipient mechanical motor faults. The controller further includes a processor programmed to receive a baseline set of current data from an operating motor and define a noise component in the baseline set of current data. The processor is also programmed to repeatedly receive real-time operating current data from the operating motor and remove the noise component from the operating current data in real-time to isolate any fault components present in the operating current data. The processor is then programmed to generate a fault index for the operating current data based on any isolated fault components.

Current Hitachi knowledge engineering systems: an overview

Energy Technology Data Exchange (ETDEWEB)

Masui, S; Maeda, A; Masuishi, T [Hitachi, Ltd., Tokyo (Japan)

1992-02-01

In order to bring the knowledge engineering technology up to the practical phase, Hitachi has provided several knowledge engineering system products, including expert system building tools, knowledge acquisition tools, and many kinds of stand-alone and build-in expert systems in both the business and process control fields. In this review article, an overview of Hitachi{prime}s recent knowledge systems is described, which includes a trend analysis on recent market recognition. In addition, to introduce the Hitachi{prime}s current activities, a new product, a user interface building tool, and a new method of tuning fuzzy membership functions using a neuro-computing algorithm are also described. Furthermore, it is pointed out that not only practical tools and methodologies, but also a practical development team, including a planning section, a cooperating expert, a user section, and experienced knowledge engineers, is needed to achieve practical expert systems. 20 refs., 10 figs., 1 tab.

Current technological trends in development of NPP systems

International Nuclear Information System (INIS)

Florescu, Gheorghe; Panaitescu, Valeriu

2010-01-01

The recent nuclear research issues look for new technologies and continuous progress in finding different and efficient solutions for sustained and upraising energy demand. The trend of increasing energy consumption and occurring of new and large consumers, especially from Asian countries, imposes finding of new means for clean, large scale and sustained energy production. NPPs availability was continuously monitored and improved; at the same time the safety of the nuclear energy production was under surveillance. The present development of the new technologies, the discoveries of new materials and development of efficient technological processes offer the opportunities for their appropriate implementation and use in the NPP system configurations and functioning/operation. The new technologies and scientific discoveries, and also the international cooperation, offer the opportunities to mitigate the actual barriers in order to cumulate and use advanced energy production, to find new energy sources and to build improved, reliable and safe power plants. The monitoring systems, intelligent sensors and SSCs, nanotechnologies and new/intelligent materials constitute the main ways for improvement of the NPP systems configuration and processes. The paper presents: - The state of the art in the level of the currently applied technologies for nuclear power systems development; - The actual technological limits that need to be over passed for improving the NPP systems ; - The main systems that need improvement and reconfiguration for development of currently operating NPPs as well as raising the operation efficiency, availability and total safety; - The actual energy production issues; - The key arguments in sustaining the R and D new NPP systems development; - Future trends in NPP development; - The limitations in industrial processes knowledge and use. Appropriate R and D in the field of NPP systems have specific characteristics that were considered in paper completion

New current control based MPPT technique for single stage grid connected PV systems

International Nuclear Information System (INIS)

Jain, Sachin; Agarwal, Vivek

2007-01-01

This paper presents a new maximum power point tracking algorithm based on current control for a single stage grid connected photovoltaic system. The main advantage of this algorithm comes from its ability to predict the approximate amplitude of the reference current waveform or power that can be derived from the PV array with the help of an intermediate variable β. A variable step size for the change in reference amplitude during initial tracking helps in fast tracking. It is observed that if the reference current amplitude is greater than the array capacity, the system gets unstable (i.e. moves into the positive slope region of the p-v characteristics of the array). The proposed algorithm prevents the PV system from entering the positive slope region of the p-v characteristics. It is also capable of restoring stability if the system goes unstable due to a sudden environmental change. The proposed algorithm has been tested on a new single stage grid connected PV configuration recently developed by the authors to feed sinusoidal current into the grid. The system is operated in a continuous conduction mode to realize advantages such as low device current stress, high efficiency and low EMI. A fast MPPT tracker with single stage inverter topology operating in CCM makes the overall system highly efficient. Specific cases of the system, operating in just discontinuous current mode and discontinuous current mode and their relative merits and demerits are also discussed

A new on-line leakage current monitoring system of ZnO surge arresters

International Nuclear Information System (INIS)

Lee, Bok-Hee; Kang, Sung-Man

2005-01-01

This paper presents a new on-line leakage current monitoring system of zinc oxide (ZnO) surge arresters. To effectively diagnose the deterioration of ZnO surge arresters, a new algorithm and on-line leakage current detection device, which uses the time-delay addition method, for discriminating the resistive and capacitive currents was developed to use in the aging test and durability evaluation for ZnO arrester blocks. A computer-based measurement system of the resistive leakage current, the on-line monitoring device can detect accurately the leakage currents flowing through ZnO surge arresters for power frequency ac applied voltages. The proposed on-line leakage current monitoring device of ZnO surge arresters is more highly sensitive and gives more linear response than the existing devices using the detection method of the third harmonic leakage currents. Therefore, the proposed leakage current monitoring device can be useful for predicting the defects and performance deterioration of ZnO surge arresters in power system applications

Current status of ITER I&C system as integration begins

Energy Technology Data Exchange (ETDEWEB)

Davis, William, E-mail: william.davis@iter.org [ITER Organisation, Route de Vinon-sur Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Wallander, Anders [ITER Organisation, Route de Vinon-sur Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Yonekawa, Izuru [Nippon Advanced Technology Ltd., 3129-45 Hibara Muramatsu, Tokai, Naka-gun, Ibaraki 319-1112 (Japan)

2016-11-15

Highlights: • The ITER I&C system is organisationally complicated and technically challenging. • Standard technologies for the ITER I&C systems have been selected. • Supply of non-standard technologies will cause serious issues. • Differing levels of design maturity of plant I&C systems is a serious challenge. • Systems are in the final stages of design and are being delivered to site. - Abstract: The ITER I&C system is organisationally complicated and technically challenging, and integrating its many sub-systems into a single coherent system is critical for the ITER project to meet its objectives. This paper explains the integration risks being faced now and anticipated in the near future. Standardisation initiatives by the ITER central team to mitigate these risks are described. The paper also presents the architecture of the ITER I&C system, the current status of design and manufacture key developments made in recent years, and the current and future activities of the central I&C teams. Finally, a short description is given of the plant I&C systems that will be delivered to ITER in the near future.

System and method for motor fault detection using stator current noise cancellation

Science.gov (United States)

Zhou, Wei; Lu, Bin; Nowak, Michael P.; Dimino, Steven A.

2010-12-07

A system and method for detecting incipient mechanical motor faults by way of current noise cancellation is disclosed. The system includes a controller configured to detect indicia of incipient mechanical motor faults. The controller further includes a processor programmed to receive a baseline set of current data from an operating motor and define a noise component in the baseline set of current data. The processor is also programmed to acquire at least on additional set of real-time operating current data from the motor during operation, redefine the noise component present in each additional set of real-time operating current data, and remove the noise component from the operating current data in real-time to isolate any fault components present in the operating current data. The processor is then programmed to generate a fault index for the operating current data based on any isolated fault components.

The EISCAT_3D Project in Norway: E3DN

Science.gov (United States)

La Hoz, C.; Oksavik, K.

2013-12-01

EISCAT_3D (E3D) is a project to build the next generation of incoherent scatter radars endowed with 3-dimensional scalar and vector capabilities that will replace the current EISCAT radars in Northern Scandinavia. One active (transmitting) site in Norway and four passive (receiving) sites in the Nordic countries will provide 3-D vector imaging capabilities by rapid scanning and multi-beam forming. The unprecedented flexibility of the solid-state transmitter with high duty-cycle, arbitrary wave-forming and polarisation and its pulsed power of 10 MW will provide unrivalled experimental capabilities to investigate the highly non-stationary and non-homogeneous state of the polar upper atmosphere. Aperture Synthesis Imaging Radar (ASIR) will to endow E3D with imaging capabilities in 3-dimensions that includes sub-beam resolution. Complemented by pulse compression, it will provide 3-dimensional images of certain types of incoherent scatter radar targets resolved to about 100 metres at 100 km range, depending on the signal-to-noise ratio. The Norwegian scientific programme is inspired by the pioneer polar scientist Kristian Birkeland (picture) and includes pressing questions on polar upper atmospheric research, among others: (Q1) How to proceed beyond the present simplistic, static, stationary and homogeneous analysis of upper atmospheric and ionospheric processes? (Q2) How does space weather affect ionospheric processes and how to support modelling and space weather services? (Q3) How to advance fundamental plasma physics by employing the ionosphere as a natural plasma physics laboratory? (Q4) How does the influx of extraterrestrial material interact with the upper atmosphere and where does the material originate from? (Q5) How does solar activity couple from geospace into the lower atmosphere and climate system, and does this energy change the wave forcing of geospace from below? Kristian Birkeland, Norwegian scientist and pioneer in polar and auroral research.

Electronic system for the automation of current measurements produced by ionization chambers

International Nuclear Information System (INIS)

Brancaccio, Franco; Dias, Mauro da Silva

2002-01-01

Ionization Chambers in current mode operation are usually used in Nuclear Metrology in the determination of radionuclide activity. For this purpose measurements of very low ionization currents, in the range of 10 -8 to 10 -14 A, are required. Usually, electrometers perform the current integration method under command of signals from an automation system, in order to reduce the measurement uncertainties. In the present work, an automation system, developed for current integration measurements at the Laboratorio de Metrologia Nuclear (LMN) of Instituto de Pesquisas Energeticas e Nucleares (IPEN), is described. This automation system is composed by software (graphic interface and control) and an electronic module connected to a microcomputer, by means of a commercial data acquisition card CAD12/32 (LYNX Tecnologia Eletronica Ltda.). Measurements, using an electrometer Keithley 616 (Keithley Instruments, Inc) and an ionization chamber IG12/A20 (20 th Century Electronics Ltd.), were performed in order to check the system and for validating the project. (author)

Fault Ride-through Capability Enhancement of Voltage Source Converter-High Voltage Direct Current Systems with Bridge Type Fault Current Limiters

Directory of Open Access Journals (Sweden)

Md Shafiul Alam

2017-11-01

Full Text Available This paper proposes the use of bridge type fault current limiters (BFCLs as a potential solution to reduce the impact of fault disturbance on voltage source converter-based high voltage DC (VSC-HVDC systems. Since VSC-HVDC systems are vulnerable to faults, it is essential to enhance the fault ride-through (FRT capability with auxiliary control devices like BFCLs. BFCL controllers have been developed to limit the fault current during the inception of system disturbances. Real and reactive power controllers for the VSC-HVDC have been developed based on current control mode. DC link voltage control has been achieved by a feedback mechanism such that net power exchange with DC link capacitor is zero. A grid-connected VSC-HVDC system and a wind farm integrated VSC-HVDC system along with the proposed BFCL and associated controllers have been implemented in a real time digital simulator (RTDS. Symmetrical three phase as well as different types of unsymmetrical faults have been applied in the systems in order to show the effectiveness of the proposed BFCL solution. DC link voltage fluctuation, machine speed and active power oscillation have been greatly suppressed with the proposed BFCL. Another significant feature of this work is that the performance of the proposed BFCL in VSC-HVDC systems is compared to that of series dynamic braking resistor (SDBR. Comparative results show that the proposed BFCL is superior over SDBR in limiting fault current as well as improving system fault ride through (FRT capability.

Survey of Digital Feedback Systems in High Current Storage Rings

International Nuclear Information System (INIS)

Teytelman, Dmitry

2003-01-01

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

EDDYTRAN program system for eddy current, electromagnetic force and structural analysis

International Nuclear Information System (INIS)

Kameari, A.; Nikura, S.

1983-01-01

A computer program system (EDDYTRAN), which is applicable to torus structures of magnetic fusion devices, has been developed to calculate the eddy current, electromagnetic force and structural analysis. The program system is designed to perform the following functions sequentially: 1) generation of model mesh and other data such as electromagnetic and mechanical properties of finite elements and boundary conditions, 2) calculations of eddy currents and electromagnetic forces, 3) transformation of the resultant force to load data fit to the structural analysis program, 4) structural analysis and 5) post-processing of the results. The EDDYTRAN utilizes the EDDYCUFF (EDDY CUrrent, magnetic Field and electromagnetic Force) program and the NASTRAN (NASA STRuctural ANalysis) program. Here, the EDDYCUFF program which has been developed by the authors is a generalized computer program to calculate transient eddy currents, resultant magnetic fields and electromagnetic forces in the conductive components. This paper describes the outline of the EDDYTRAN program system and preliminary results obtained through the application to the Tokamak reactor design which was performed for the Japan Atomic Energy Research Institute

Intense relativistic electron beam injector system for tokamak current drive

International Nuclear Information System (INIS)

Bailey, V.L.; Creedon, J.M.; Ecker, B.M.; Helava, H.I.

1983-01-01

We report experimental and theoretical studies of an intense relativistic electron beam (REB) injection system designed for tokamak current drive experiments. The injection system uses a standard high-voltage pulsed REB generator and a magnetically insulated transmission line (MITL) to drive an REB-accelerating diode in plasma. A series of preliminary experiments has been carried out to test the system by injecting REBs into a test chamber with preformed plasma and applied magnetic field. REBs were accelerated from two types of diodes: a conventional vacuum diode with foil anode, and a plasma diode, i.e., an REB cathode immersed in the plasma. REB current was in the range of 50 to 100 kA and REB particle energy ranged from 0.1 to 1.0 MeV. MITL power density exceeded 10 GW/cm 2 . Performance of the injection system and REB transport properties is documented for plasma densities from 5 x 10 12 to 2 x 10 14 cm -3 . Injection system data are compared with numerical calculations of the performance of the coupled system consisting of the generator, MITL, and diode

Seasonality of the Mindanao Current/Undercurrent System

Science.gov (United States)

Ren, Qiuping; Li, Yuanlong; Wang, Fan; Song, Lina; Liu, Chuanyu; Zhai, Fangguo

2018-02-01

Seasonality of the Mindanao Current (MC)/Undercurrent (MUC) system is investigated using moored acoustic Doppler current profiler (ADCP) measurements off Mindanao (8°N, 127.05°E) and ocean model simulations. The mooring observation during December 2010 to August 2014 revealed that the surface-layer MC between 50-150 m is dominated by annual-period variation and tends to be stronger in spring (boreal) and weaker in fall. Prominent semiannual variations were detected below 150 m. The lower MC between 150 and 400 m is stronger in spring and fall and weaker in summer and winter, while the northward MUC below 400 m emerges in summer and winter and disappears in spring and fall. In-phase and out-of-phase current anomalies above and below 150 m were observed alternatively. These variations are faithfully reproduced by an eddy-resolving ocean model simulation (OFES). Further analysis demonstrates that seasonal variation of the MC is a component of large-scale upper-ocean circulation gyre, while current variations in the MUC layer are confined near the western boundary and featured by shorter-scale (200-400 km) structures. Most of the MC variations and approximately half of the MUC variations can be explained by the first and second baroclinic modes and caused by local wind forcing of the western Pacific. Semiannual surface wind variability and superimposition of the two baroclinic modes jointly give rise to the enhanced subsurface semiannual variations. The pronounced mesoscale eddy variability in the MUC layer may also contribute to the seasonality of the MUC through eddy-current interaction.

Approximative calculation of transient short-circuit currents in power-systems

Energy Technology Data Exchange (ETDEWEB)

Heuck, K; Rosenberger, R; Dettmann, K D; Kegel, R

1986-08-01

The paper shows that it is approximatively possible to calculate the transient short-circuit currents for symmetrical and asymmetrical faults in power-systems. For that purpose a simple equivalent network is found. Its error of approximation is small. For the important maximum short-circuit current limits of error are pointed out compared to VDE 0102.

A DSP-Based Beam Current Monitoring System for Machine Protection Using Adaptive Filtering

International Nuclear Information System (INIS)

J. Musson; H. Dong; R. Flood; C. Hovater; J. Hereford

2001-01-01

The CEBAF accelerator at Jefferson Lab is currently using an analog beam current monitoring (BCM) system for its machine protection system (MPS), which has a loss accuracy of 2 micro-amps. Recent burn-through simulations predict catastrophic beam line component failures below 1 micro-amp of loss, resulting in a blind spot for the MPS. Revised MPS requirements target an ultimate beam loss accuracy of 250 nA. A new beam current monitoring system has been developed which utilizes modern digital receiver technology and digital signal processing concepts. The receiver employs a direct-digital down converter integrated circuit, mated with a Jefferson Lab digital signal processor VME card. Adaptive filtering is used to take advantage of current-dependent burn-through rates. Benefits of such a system include elimination of DC offsets, generic algorithm development, extensive filter options, and interfaces to UNIX-based control systems

Elimination of the Inrush Current Phenomenon Associated with Single-Phase Offline UPS Systems

Directory of Open Access Journals (Sweden)

Syed Sabir Hussain Bukhari

2016-02-01

Full Text Available Critical load applications always rely on UPS systems to uphold continuous power during abnormal grid conditions. In case of any power disruption, an offline UPS system starts powering the load to avoid blackout. However, this process can root the momentous inrush current for the transformer installed before the load. The consequences of inrush current can be the reduction of output voltage and tripping of protective devices of the UPS system. Furthermore, it can also damage the sensitive load and decrease the transformer’s lifetime. To prevent the inrush current, and to avoid its disruptive effects, this research suggests an offline UPS system based on a current regulated inverter that eliminates the inrush current while powering the transformer coupled loads. A detailed comparative analysis of the conventional and proposed topologies is presented and the experiment was performed by using a small prototype to validate the performance, and operation of the proposed topology.

Current practice and developmental efforts for leak detection in US reactor primary systems

International Nuclear Information System (INIS)

Kupperman, D.S.; Claytor, T.N.

1985-07-01

Current leak detection practices in 74 operating nuclear reactors have been reviewed. Existing leak detection systems are adequate to ensure a leak-before-break scenario in most situations, but no currently available, single method combines optimal leakage detection sensitivity, leak-locating ability, and leakage measurement accuracy. Simply tightening current leakage limits may produce an unacceptably large number of unnecessary shutdowns. The use of commercially available acoustic monitoring systems or moisture-sensitive tape may improve leak detection capability at specific sites. However, neither of these methods currently provides source discrimination (e.g., to distinguish between leaks from pipe cracks and valves) or leak-rate information (a small leak may saturate the system). A field-implementable acoustic leak detection system is being developed to address these limitations. 5 refs., 3 figs

An assessment of the current municipal solid waste management system in Lahore, Pakistan.

Science.gov (United States)

Masood, Maryam; Barlow, Claire Y; Wilson, David C

2014-09-01

The current status of solid waste management in Lahore, a metropolitan city of Pakistan, is reviewed in this article using an existing approach, the UN-Habitat city profile. This involves a systematic quantitative and qualitative assessment of physical components and governance features of the current waste management system. A material flow diagram (MFD) is developed, which allows visualisation of the current waste management system with all related inputs and outputs. This study shows that in the current system, waste collection and transportation is the main focus, however the collection coverage is only about 68%. There is no controlled or even semi-controlled waste disposal facility in Lahore. There is no official recycling system in the city. It is estimated that currently ~27% of waste by weight is being recycled through the informal sector. Making use of the organic content of the waste, a composting facility is operative in the city, producing 47,230 tonnes year(-1) of organic compost. Lahore does not perform very well in governance features. Inclusivity of users and providers of the waste management system is low in the city, as not all stakeholders are consulted in the decision making processes. Waste management costs US$20 per tonne of waste, where the main focus is only on waste collection, and the current user fees are much lower than the actual costs. This study recommends that recycling should be promoted by increasing public awareness and integrating the informal sector to make the current system sustainable and financially viable. © The Author(s) 2014.

Automated WWER steam generator eddy current testing and plugging control system

International Nuclear Information System (INIS)

Gorecan, I.; Gortan, K.; Grzalja, I.

2004-01-01

The structural architecture of the system contains three main components which are described as follows: Manipulator Guidance System; Eddy Current Testing System; Plugging System. The manipulator system has the task to position the end-effectors to the desired tube position. When the final position is reached, the Eddy Current testing system performs data acquisition. In case defects are found, the plugging system performs tube plug installment. Each system is composed of 3 layers. The first layer is the hardware layer consisting of motors driving the effectors along with sensors needed to obtain the positioning data, pusher motors used to push the test probes into tubes of the WWER steam generator, and plugging hardware tool. The second layer is the control box performing basic monitoring and control routines as an interconnection between first and third layer. The highest layer is the control software, running on the PC, which is used as a human-machine-interface.(author)

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.

Brake Performance Analysis of ABS for Eddy Current and Electrohydraulic Hybrid Brake System

OpenAIRE

Ren He; Xuejun Liu; Cunxiang Liu

2013-01-01

This paper introduces an eddy current and electro-hydraulic hybrid brake system to solve problems such as wear, thermal failure, and slow response of traditional vehicle brake system. Mathematical model was built to calculate the torque of the eddy current brake system and hydraulic brake system and analyze the braking force distribution between two types of brake systems. A fuzzy controller on personal computer based on LabVIEW and Matlab was designed and a set of hardware in the loop system...

Peculiarities of the risk management system organization in current conditions

OpenAIRE

MIKHIN P.O.

2014-01-01

Risk-management system organization problem is topical nowadays. The innovation activity is defined as an activity vulnerable to risk and needs more attention. The basic approaches and elements of organization structure development in risk-management system are considered to find out the best structure for business modelling usage. Balance and combination of risk-management system types are required in current conditions.

Improvement of bunch-by-bunch beam current detection system in Hefei light source

International Nuclear Information System (INIS)

Zheng Kai; Wang Junhua; Liu Zuping; Li Weimin; Zhou Zeran; Yang Yongliang; Huang Longjun; Chen Yuanbo

2006-01-01

Bunch-by-bunch beam current detection system is an important facility in the multibunch storage ring. In this paper, the established bunch-by-bunch beam current detection systems for the accelerator such as Cornell, SLAC and KEKB were compared and studied. The design of the bunch-by-bunch beam current detection system for HLS, which was based on the bunch-by-bunch tracing measurement system in HLS was given. Both demodulation by sine wave and square were applied in this paper, the deviation of the detect system was determined by the longitudinal oscillation. Compared the data acquired from ADC with the data from DCCT, the ADC data was scaled by the bunch current. The standard deviations of linear fit were about 1%, and the standard deviations of polynomial fit were less than 0.5% in both sine wave and square wave demodulation. Some analysis of the measurement results also had been shown in this paper. (authors)

Plasma position and current control system enhancements for the JET ITER-like wall

Energy Technology Data Exchange (ETDEWEB)

De Tommasi, G. [Associazione EURATOM-ENEA-CREATE, Univ. di Napoli Federico II, Via Claudio 21, 80125 Napoli (Italy); Maviglia, F. [Associazione EURATOM-ENEA-CREATE, Via Claudio 21, 80125 Napoli (Italy); Neto, A.C. [Ass. EURATOM-IST, Instituto de Plasmas e Fusão Nuclear, IST, 1049-001 Lisboa (Portugal); Lomas, P.J.; McCullen, P.; Rimini, F.G. [Euratom-CCFE, Culham Science Centre, OX14 3DB Abingdon (United Kingdom)

2014-03-15

Highlights: • JET plasma position and current control system enhanced for the JET ITER like wall. • Vertical stabilization system enhanced to speed up its response and to withstand larger perturbations. • Improved termination management system. • Implementation of the current limit avoidance system. • Implementation of PFX-on-early-task. - Abstract: The upgrade of Joint European Torus (JET) to a new all-metal wall, the so-called ITER-like wall (ILW), has posed a set of new challenges regarding both machine operation and protection. The plasma position and current control (PPCC) system plays a crucial role in minimizing the possibility that the plasma could permanently damage the ILW. The installation of the ILW has driven a number of upgrades of the two PPCC components, namely the Vertical Stabilization (VS) system and the Shape Controller (SC). The VS system has been enhanced in order to speed up its response and to withstand larger perturbations. The SC upgrade includes three new features: an improved termination management system, the current limit avoidance system, and the PFX-on-early-task. This paper describes the PPCC upgrades listed above, focusing on the implementation issues and on the experimental results achieved during the 2011–12 JET experimental campaigns.

High voltage power supplies for ITER RF heating and current drive systems

International Nuclear Information System (INIS)

Gassmann, T.; Arambhadiya, B.; Beaumont, B.; Baruah, U.K.; Bonicelli, T.; Darbos, C.; Purohit, D.; Decamps, H.; Albajar, F.; Gandini, F.; Henderson, M.; Kazarian, F.; Lamalle, P.U.; Omori, T.; Parmar, D.; Patel, A.; Rathi, D.; Singh, N.P.

2011-01-01

The RF heating and current drive (H and CD) systems to be installed for the ITER fusion machine are the electron cyclotron (EC), ion cyclotron (IC) and, although not in the first phase of the project, lower hybrid (LH). These systems require high voltage, high current power supplies (HVPS) in CW operation. These HVPS should deliver around 50 MW electrical power to each of the RF H and CD systems with stringent requirements in terms of accuracy, voltage ripple, response time, turn off time and fault energy. The PSM (Pulse Step Modulation) technology has demonstrated over the past 20 years its ability to fulfill these requirements in many industrial facilities and other fusion reactors and has therefore been chosen as reference design for the IC and EC HVPS systems. This paper describes the technical specifications, including interfaces, the resulting constraints on the design, the conceptual design proposed for ITER EC and IC HVPS systems and the current status.

Determining the Frequency for Load-Independent Output Current in Three-Coil Wireless Power Transfer System

Directory of Open Access Journals (Sweden)

Longzhao Sun

2015-09-01

Full Text Available Conditions for load-independent output voltage or current in two-coil wireless power transfer (WPT systems have been studied. However, analysis of load-independent output current in three-coil WPT system is still lacking in previous studies. This paper investigates the output current characteristics of a three-coil WPT system against load variations, and determines the operating frequency to achieve a constant output current. First, a three-coil WPT system is modeled by circuit theory, and the analytical expression of the root-mean-square of the output current is derived. By substituting the coupling coefficients, the quality factor, and the resonant frequency of each coil, we propose a method of calculating the frequency for load-independent output current in a three-coil WPT system, which indicates that there are two frequencies that can achieve load-independent output current. Experiments are conducted to validate these analytical results.

Coral Reef Surveys at 21 Sites in American Samoa during 2002 (NODC Accession 0000735)

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — Transects of the coral colonies at 21 sites in American Samoa were surveyed by Dr. Charles Birkeland during an underwater swim in March 2002. Data for each coral...

Addressing Circuitous Currents MVDC Power Systems Protection

Science.gov (United States)

2017-12-31

Addressing Circuitous Currents MVDC Power Systems Protection 5b. GRANT NUMBER N00014-16-1-3113 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR($) Sd. PROJECT NUMBER...efficiency. A challenge with DC distribution is electrical protection . Z-source DC breakers alt! an pti n b&i g cvr.sidcrcd and this w rk ~xplores...zonal distribution, electric ship 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF a. REPORT b. ABSTRACT c. THIS PAGE ABSTRACT u u u uu 18. NUMBER

A Lower Hybrid Current Drive System for Alcator C-Mod

International Nuclear Information System (INIS)

Bernabei, S.; Hosea, J.C.; Loesser, D.; Rushinski, J.; Wilson, J.R.; Bonoli, P.; Grimes, M.; Parker, R.; Porkolab, M.; Terry, D.; Woskov, P.

2001-01-01

A Lower Hybrid Current Drive system is being constructed jointly by Plasma Science and Fusion Center (PSFC) and Princeton Plasma Physics Laboratory (PPPL) for installation on the Alcator C-Mod tokamak, with the primary goal of driving plasma current in the outer region of the plasma. The Lower Hybrid (LH) system consists of 3 MW power at 4.6 GHz with a maximum pulse length of 5 seconds. Twelve klystrons will feed an array of 4-vertical and 24-horizontal waveguides mounted in one equatorial port. The coupler will incorporate some compact characteristics of the multijunction power splitting while retaining full control of the toroidal phase. In addition a dynamic phase control system will allow feedback stabilization of MHD modes. The desire to avoid possible waveguide breakdown and the need for compactness have resulted in some innovative technical solution which will be presented

Current status of technology development on remote monitoring system

International Nuclear Information System (INIS)

Yoon, Wan Ki; Lee, Y. K.; Lee, Y. D.; Na, W. W.

1997-03-01

IAEA is planning to perform the remote monitoring system in nuclear facility in order to reinforce the economical and efficient inspection. National lab. in U.S. is developing the corresponding core technology and field trial will be done to test the remote monitoring system by considering the case that it replace the current safeguards system. U.S. setup the International Remote Monitoring Project to develop the technology. IAEA makes up remote monitoring team and setup the detail facility to apply remote monitoring system. Therefore, early participation in remote monitoring technology development will make contribution in international remote monitoring system and increase the transparency and confidence in domestic nuclear activities. (author). 12 refs., 20 figs

A real-time current driving control system for the TJ-II coils

International Nuclear Information System (INIS)

Pena, Angel de la; Pacios, Luis; Carrasco, Ricardo; Lapayese, Fernando

2009-01-01

Since the start of plasma operation in the TJ-II stellarator, the required values of DC currents that are fed to its different coil sets have been controlled to high precision along the complete discharge flat-top. As a result each current configuration produced a highly stable magnetic-field configuration. Recently, the configurational flexibility of the TJ-II has been broadened by the commissioning of a new mode of operation that allows magnetic configurations to be varied dynamically during the discharge flat-top. In order to achieve this, new hardware and software features have been added to the TJ-II Control System. These new features may also provide new strategies for feedback control in accordance with parameters measured in one or more diagnostics. In this new set-up, coil current profiles are generated and controlled to millisecond timescales by a system based on VMEbus and OS9 real-time operating system. A new communication middleware architecture called XML-based Messages Distribution Service (X-MDS) has been designed to exchange XML-based data with calling clients. Furthermore, with this software, a fully functional Java application for supervision and for current profiles settings has been developed. This paper provides a detailed description of the complete TJ-II real-time current-profile control system and results obtained during its operation.

A real-time current driving control system for the TJ-II coils

Energy Technology Data Exchange (ETDEWEB)

Pena, Angel de la [Association EURATOM - CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain)], E-mail: a.delapena@ciemat.es; Pacios, Luis; Carrasco, Ricardo; Lapayese, Fernando [Association EURATOM - CIEMAT, Avda. Complutense 22, 28040 Madrid (Spain)

2009-06-15

Since the start of plasma operation in the TJ-II stellarator, the required values of DC currents that are fed to its different coil sets have been controlled to high precision along the complete discharge flat-top. As a result each current configuration produced a highly stable magnetic-field configuration. Recently, the configurational flexibility of the TJ-II has been broadened by the commissioning of a new mode of operation that allows magnetic configurations to be varied dynamically during the discharge flat-top. In order to achieve this, new hardware and software features have been added to the TJ-II Control System. These new features may also provide new strategies for feedback control in accordance with parameters measured in one or more diagnostics. In this new set-up, coil current profiles are generated and controlled to millisecond timescales by a system based on VMEbus and OS9 real-time operating system. A new communication middleware architecture called XML-based Messages Distribution Service (X-MDS) has been designed to exchange XML-based data with calling clients. Furthermore, with this software, a fully functional Java application for supervision and for current profiles settings has been developed. This paper provides a detailed description of the complete TJ-II real-time current-profile control system and results obtained during its operation.

Earth's external magnetic fields at low orbital altitudes

Science.gov (United States)

Klumpar, D. M.

1990-01-01

Under our Jun. 1987 proposal, Magnetic Signatures of Near-Earth Distributed Currents, we proposed to render operational a modeling procedure that had been previously developed to compute the magnetic effects of distributed currents flowing in the magnetosphere-ionosphere system. After adaptation of the software to our computing environment we would apply the model to low altitude satellite orbits and would utilize the MAGSAT data suite to guide the analysis. During the first year, basic computer codes to run model systems of Birkeland and ionospheric currents and several graphical output routines were made operational on a VAX 780 in our research facility. Software performance was evaluated using an input matchstick ionospheric current array, field aligned currents were calculated and magnetic perturbations along hypothetical satellite orbits were calculated. The basic operation of the model was verified. Software routines to analyze and display MAGSAT satellite data in terms of deviations with respect to the earth's internal field were also made operational during the first year effort. The complete set of MAGSAT data to be used for evaluation of the models was received at the end of the first year. A detailed annual report in May 1989 described these first year activities completely. That first annual report is included by reference in this final report. This document summarizes our additional activities during the second year of effort and describes the modeling software, its operation, and includes as an attachment the deliverable computer software specified under the contract.

A Neuron Model Based Ultralow Current Sensor System for Bioapplications

Directory of Open Access Journals (Sweden)

A. K. M. Arifuzzman

2016-01-01

Full Text Available An ultralow current sensor system based on the Izhikevich neuron model is presented in this paper. The Izhikevich neuron model has been used for its superior computational efficiency and greater biological plausibility over other well-known neuron spiking models. Of the many biological neuron spiking features, regular spiking, chattering, and neostriatal spiny projection spiking have been reproduced by adjusting the parameters associated with the model at hand. This paper also presents a modified interpretation of the regular spiking feature in which the firing pattern is similar to that of the regular spiking but with improved dynamic range offering. The sensor current ranges between 2 pA and 8 nA and exhibits linearity in the range of 0.9665 to 0.9989 for different spiking features. The efficacy of the sensor system in detecting low amount of current along with its high linearity attribute makes it very suitable for biomedical applications.

Eddy Current Thermography: System Development and Its Application in NDT

International Nuclear Information System (INIS)

Nurliyana Shamimie Rusli; Ilham Mukriz Zainal Abidin; Sidek, H.A.A.

2015-01-01

Eddy Current Thermography (ECT) is an integrative technique which combines eddy current and thermographic NDT in order to provide an efficient method for defect detection. The technique is applicable to electrically conductive material and has the ability to detect surface and subsurface defect. ECT is a non-contact technique; has the ability to provide instantaneous response and high scanning speed that makes it reliable for defect detection and assessment. The technique combines electromagnetic excitation of the work-piece via a coil carrying current, heating of the material by induction and inspection by transient infrared thermography. In this paper, the development of ECT system is detailed, including coil design for global and local heating of samples, and optimisation of excitation parameters (frequency, power, heating duration etc). Results from 3D FEM simulation and experimental investigations are also presented to provide the overview of underlying phenomena and application of ECT. The work demonstrates the effectiveness of the developed ECT system and technique in defect detection and assessment. (author)

Neoclassical current and plasma rotation in helical systems

International Nuclear Information System (INIS)

Nakajima, N.; Okamoto, M.

1991-01-01

In order to clarify geometrical effects of the magnetic field on the neoclassical theory in general toroidal systems, the neoclassical parallel particle flow, heat flux, current and plasma rotation of a multispecies plasma are examined using the moment approach on the basis of the original papers under the assumptions of no fluctuations, no external sources and losses except for a fast ion beam and an external inductive electric field, steady state, and |u a | Ta where u a and v Ta are the macro and thermal velocity of species a, respectively. Hence, we might have a point of view of unifying understanding the neoclassical theory in general toroidal systems. Three collisionality regimes, i.e., the 1/ν (in non-axisymmetric toroidal systems) or banana (in axisymmetric toroidal systems), plateau, and Pfirsch-Schlueter collisionality regimes are examined separately. (author) 8 refs

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.

Computer circuit analysis of induced currents in the MFTF-B magnet system

International Nuclear Information System (INIS)

Magnuson, G.D.; Woods, E.L.

1981-01-01

An analysis was made of the induced current behavior of the MFTF-B magnet system. Although the magnet system consists of 22 coils, because of its symmetry we considered only 11 coils in the analysis. Various combinations of the coils were dumped either singly or in groups, with the current behavior in all magnets calculated as a function of time after initiation of the dump

Design of laser diode driver with constant current and temperature control system

Science.gov (United States)

Wang, Ming-cai; Yang, Kai-yong; Wang, Zhi-guo; Fan, Zhen-fang

2017-10-01

A laser Diode (LD) driver with constant current and temperature control system is designed according to the LD working characteristics. We deeply researched the protection circuit and temperature control circuit based on thermos-electric cooler(TEC) cooling circuit and PID algorithm. The driver could realize constant current output and achieve stable temperature control of LD. Real-time feedback control method was adopted in the temperature control system to make LD work on its best temperature point. The output power variety and output wavelength shift of LD caused by current and temperature instability were decreased. Furthermore, the driving current and working temperature is adjustable according to specific requirements. The experiment result showed that the developed LD driver meets the characteristics of LD.

Power crowbar system coupled by a current transformer with very low leakage inductance

International Nuclear Information System (INIS)

Kitagawa, S.; Hirano, K.I.

1976-01-01

A reliable, efficient power crowbar system has been developed for fast pinch experiments. In order to reduce the effective impedance of series capacitor system, a current transformer with extremely low leakage inductance has been designed and used. Primary and secondary windings of the transformer are alternately arranged as closely as possible. As a result, the leakage inductance is reduced to 2 nH. It is demonstrated that a current of 390 kA, the rise time of which is 4.5 μsec, is sustained for 100 μsec. Much larger system is being built, which maintains a current of 1 MA over 1 msec. The life of crowbar gap switches is prolonged by the aid of a mechanically-driven metal-to-metal contact switch. Another crowbar switch system with a high coulomb rating is under consideration, in which a gap switch is used together with a saturable reactor and a current transformer

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

Energy Technology Data Exchange (ETDEWEB)

Heydari, Hossein; Faghihi, Faramarz; Sharifi, Reza; Poursoltanmohammadi, Amir Hossein [Center of Excellence for Power System Automation and Operation, Electrical Engineering Department, Iran University of Science and Technology (IUST), Tehran (Iran, Islamic Republic of)], E-mail: heydari@iust.ac.ir, E-mail: faramarz_faghihi@ee.iust.ac.ir, E-mail: reza_sharifi@ee.iust.ac.ir, E-mail: amirhosseinp@ee.iust.ac.ir

2008-09-15

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.

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.

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

International Nuclear Information System (INIS)

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

2008-01-01

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

Current practice and developmental efforts for leak detection in U.S. reactor primary systems

International Nuclear Information System (INIS)

Kupperman, D.S.; Claytor, T.N.

1986-01-01

Current leak detection practices in 74 operating nuclear reactors have been reviewed. Existing leak detection systems are adequate to ensure a leak-before-break scenario in most situations, but no currently available, single method combines optimal leakage detection sensitivity, leak-locating ability, and leakage measurement accuracy. Simply tightening current leakage limits may produce an unacceptably large number of unnecessary shutdowns. The use of commercially available acoustic monitoring systems or moisture-sensitive tape may improve leak detection capability at specific sites. However, neither of these methods currently provides source discrimination (e.g., to distinguish between leaks from pipe cracks and valves) or leak-rate information (a small leak may saturate the system). A field-implementable acoustic leak detection system is being developed to address these limitations. 5 refs.

Nonlinear spin current generation in noncentrosymmetric spin-orbit coupled systems

Science.gov (United States)

Hamamoto, Keita; Ezawa, Motohiko; Kim, Kun Woo; Morimoto, Takahiro; Nagaosa, Naoto

2017-06-01

Spin current plays a central role in spintronics. In particular, finding more efficient ways to generate spin current has been an important issue and has been studied actively. For example, representative methods of spin-current generation include spin-polarized current injections from ferromagnetic metals, the spin Hall effect, and the spin battery. Here, we theoretically propose a mechanism of spin-current generation based on nonlinear phenomena. By using Boltzmann transport theory, we show that a simple application of the electric field E induces spin current proportional to E2 in noncentrosymmetric spin-orbit coupled systems. We demonstrate that the nonlinear spin current of the proposed mechanism is supported in the surface state of three-dimensional topological insulators and two-dimensional semiconductors with the Rashba and/or Dresselhaus interaction. In the latter case, the angular dependence of the nonlinear spin current can be manipulated by the direction of the electric field and by the ratio of the Rashba and Dresselhaus interactions. We find that the magnitude of the spin current largely exceeds those in the previous methods for a reasonable magnitude of the electric field. Furthermore, we show that application of ac electric fields (e.g., terahertz light) leads to the rectifying effect of the spin current, where dc spin current is generated. These findings will pave a route to manipulate the spin current in noncentrosymmetric crystals.

Supervisory control and data acquisition system development for superconducting current feeder system of SST-1

International Nuclear Information System (INIS)

Patel, R.; Mahesuria, G.; Gupta, N.C.; Sonara, D.; Panchal, R.; Panchal, P.; Tanna, V.L.; Pradhan, S.

2014-01-01

The Current Feeders System (CFS) is essentially an optimized bridge between the power supply at room temperature and Super Conducting Magnet System (SCMS) of the SST-1 machine at 4.5 K.CFS is a complex electrical and cryogenic network which consists of ten pairs of 10 KA rating helium Vapor cooled Conventional Current Leads (VCCLs), superconducting (SC) current feeder and associated components. For the safe and reliable operation of CFS, it is equipped with different physical process parameters measuring instruments like flow, pressure, temperature, level, vacuum, voltage taps and final control element like control valves, heaters, vacuum pumps etc. PLC program is developed in ladder language for acquiring and controlling the process parameters. Independent SCADA applications developed in WonderwareIntouch software for data communication from PLC, front-end Graphical User Interface (GUI), auto-manual interface, real time trends, history trends, events and alarm pages. Time synchronized communication established between CFS control system and Industrial SQL server (InSQL) Historian for centralized storage of CFS process parameters which intern provides the CFS process data to SST-1 central control room. SCADA based data acquisition and data retrieval system is found to be satisfactory during the recent SST-1 cool down experiment. This paper describes the SCADA and PLC application development and their communication to InSQL server. (author)

Automation of eddy current system for in-service inspection of turbine and generator bores

International Nuclear Information System (INIS)

Viertl, J.R.M.

1988-01-01

The most commonly applied inspection method for ferromagnetic turbine and generator rotor bores is the magnetic particle test technique. This method is subjective, depends on the test operator's skill and diligence in identifying test indications, and suffers from poor repeatability, especially for small indications. Automation would improve repeatability. However, magnetic particle tests are not easily automated, because the data are in the form of sketches, photographs, and written and oral descriptions of the indications. Eddy current inspection has obvious potential to replace magnetic particle methods in this application. Eddy current tests can be readily automated, as the data are in the form of voltages that can be recorded, digitized, and manipulated by a computer. The current project continues the investigation of the correlation between eddy current and magnetic particle inspection. Two systems have been combined to acquire eddy current data automatically. This combination of systems consists of the Nortec-25L Eddyscope (to provide the analog eddy current signals) and the General Electric DATAQ (TM) System (to perform the automatic data acquisition). The automation of the system is discussed

Current-limiting and ultrafast system for the characterization of resistive random access memories.

Science.gov (United States)

Diaz-Fortuny, J; Maestro, M; Martin-Martinez, J; Crespo-Yepes, A; Rodriguez, R; Nafria, M; Aymerich, X

2016-06-01

A new system for the ultrafast characterization of resistive switching phenomenon is developed to acquire the current during the Set and Reset process in a microsecond time scale. A new electronic circuit has been developed as a part of the main setup system, which is capable of (i) applying a hardware current limit ranging from nanoampers up to miliampers and (ii) converting the Set and Reset exponential gate current range into an equivalent linear voltage. The complete system setup allows measuring with a microsecond resolution. Some examples demonstrate that, with the developed setup, an in-depth analysis of resistive switching phenomenon and random telegraph noise can be made.

Development and experiment of a 60 kW horizontal-axis marine current power system

International Nuclear Information System (INIS)

Xu, Quan-kun; Liu, Hong-wei; Lin, Yong-gang; Yin, Xiu-xing; Li, Wei; Gu, Ya-jing

2015-01-01

A 60 kW horizontal-axis marine current power system is designed, built and tested to provide potentially cost-competitive electrical power for residents in remote islands. This power system mainly consists of a three-bladed marine current turbine, a drive-train system, power electronics and a control console. The turbine blade parameters are reasonably calculated and optimized based on the blade element momentum theory. The hydrodynamic performances of this turbine are predicted over a wide range of operating conditions. An adequate drive-train system is carefully designed to make the marine power system work smoothly and quietly even under harsh marine current conditions. The control console is also developed to facilitate the condition monitoring and generator power and speed regulations for this power system by adequately controlling the onshore power electronics. This power system has been tested under real marine current conditions to thoroughly evaluate its dynamic characteristics and effectiveness. - Highlights: • A 60°kW horizontal-axis marine current power system is designed, built and tested. • Detailed design procedure and experimental data are provided. • Experimental results demonstrate high power convention efficiency of the system

Preliminary analysis of accident in SST-1 current feeder system

International Nuclear Information System (INIS)

Roy, Swati; Kanabar, Deven; Garg, Atul; Singh, Amit; Tanna, Vipul; Prasad, Upendra; Srinivasan, R.

2017-01-01

Steady-state Tokamak-1 (SST-1) has 16 superconducting Toroidal field (TF) and 9 superconducting poloidal field (PF) coils rated for 10kA DC. All the TF are connected in series and are operated in DC condition whereas PF coils are individually operated in pulse mode during SST-1 campaigns. SST-1 current feeder system (CFS) houses 9 pairs of PF current leads and 1 pair of TF current leads. During past SST-1 campaign, there were arcing incidents within SST-1 CFS chamber which caused significant damage to PF superconducting current leads as well as its Helium cooling lines of the current leads. This paper brings out the preliminary analysis of the mentioned arcing incident, possible reasons and its investigation thereby laying out the sequence of events. From this analysis and observations, various measures to avoid such arcing incidents have also been proposed. (author)

An improved current control scheme for grid-connected DG unit based distribution system harmonic compensation

DEFF Research Database (Denmark)

He, Jinwei; Wei Li, Yun; Wang, Xiongfei

2013-01-01

In order to utilize DG unit interfacing converters to actively compensate distribution system harmonics, this paper proposes an enhanced current control approach. It seamlessly integrates system harmonic mitigation capabilities with the primary DG power generation function. As the proposed current...... controller has two well decoupled control branches to independently control fundamental and harmonic DG currents, phase-locked loops (PLL) and system harmonic component extractions can be avoided during system harmonic compensation. Moreover, a closed-loop power control scheme is also employed to derive...... the fundamental current reference. The proposed power control scheme effectively eliminates the impacts of steady-state fundamental current tracking errors in the DG units. Thus, an accurate power control is realized even when the harmonic compensation functions are activated. Experimental results from a single...

Design of ITER-FEAT RF heating and current drive systems

International Nuclear Information System (INIS)

Bosia, G.; Kobayashi, N.; Ioki, K.; Bibet, P.; Koch, R.; Chavan, R.; Tran, M.Q.; Takahashi, K.; Kuzikov, S.; Vdovin, V.

2001-01-01

Three radio frequency (RF) heating and current drive (H and CD) systems are being designed for ITER-FEAT: an electron cyclotron (EC), an ion cyclotron (IC) and a lower hybrid (LH) System. The launchers of the RF systems use four ITER equatorial ports and are fully interchangeable. They feature equal power outputs (20 MW/port), similar neutron shielding performance, and identical interfaces with the other machine components. An outline of the design is given in the paper. (author)

Medical telerobotic systems: current status and future trends.

Science.gov (United States)

Avgousti, Sotiris; Christoforou, Eftychios G; Panayides, Andreas S; Voskarides, Sotos; Novales, Cyril; Nouaille, Laurence; Pattichis, Constantinos S; Vieyres, Pierre

2016-08-12

Teleoperated medical robotic systems allow procedures such as surgeries, treatments, and diagnoses to be conducted across short or long distances while utilizing wired and/or wireless communication networks. This study presents a systematic review of the relevant literature between the years 2004 and 2015, focusing on medical teleoperated robotic systems which have witnessed tremendous growth over the examined period. A thorough insight of telerobotics systems discussing design concepts, enabling technologies (namely robotic manipulation, telecommunications, and vision systems), and potential applications in clinical practice is provided, while existing limitations and future trends are also highlighted. A representative paradigm of the short-distance case is the da Vinci Surgical System which is described in order to highlight relevant issues. The long-distance telerobotics concept is exemplified through a case study on diagnostic ultrasound scanning. Moreover, the present review provides a classification into short- and long-distance telerobotic systems, depending on the distance from which they are operated. Telerobotic systems are further categorized with respect to their application field. For the reviewed systems are also examined their engineering characteristics and the employed robotics technology. The current status of the field, its significance, the potential, as well as the challenges that lie ahead are thoroughly discussed.

West Coast Observing System (WCOS) ADCP Currents Data, 2004-2008

Data.gov (United States)

National Oceanic and Atmospheric Administration, Department of Commerce — The West Coast Observing System (WCOS) project provides access to temperature and currents data collected at four of the five National Marine Sanctuary sites,...

Current trauma care system and trauma care training in China

Directory of Open Access Journals (Sweden)

Lian-Yang Zhang

2018-04-01

Full Text Available Trauma is a life-threatening “modern disease”. The outcomes could only be optimized by cost-efficient and prompt trauma care, which embarks on the improvement of essential capacities and conceptual revolution in addition to the disruptive innovation of the trauma care system. According to experiences from the developed countries, systematic trauma care training is the cornerstone of the generalization and the improvement on the trauma care, such as the Advance Trauma Life Support (ATLS. Currently, the pre-hospital emergency medical services (EMS has been one of the essential elements of infrastructure of health services in China, which is also fundamental to the trauma care system. Hereby, the China Trauma Care Training (CTCT with independent intellectual property rights has been initiated and launched by the Chinese Trauma Surgeon Association to extend the up-to-date concepts and techniques in the field of trauma care as well to reinforce the generally well-accepted standardized protocols in the practices. This article reviews the current status of the trauma care system as well as the trauma care training. Keywords: Trauma care system, Trauma care training, China

The current situation of treatment systems for alcoholism in Korea.

Science.gov (United States)

Kim, Jee Wook; Lee, Boung Chul; Kang, Tae-Cheon; Choi, Ihn-Geun

2013-02-01

Alcoholism is becoming one of the most serious issues in Korea. The purpose of this review article was to understand the present status of the treatment system for alcoholism in Korea compared to the United States and to suggest its developmental direction in Korea. Current modalities of alcoholism treatment in Korea including withdrawal treatment, pharmacotherapy, and psychosocial treatment are available according to Korean evidence-based treatment guidelines. Benzodiazepines and supportive care including vitamin and nutritional support are mainly used to treat alcohol withdrawal in Korea. Naltrexone and acamprosate are the drugs of first choice to treat chronic alcoholism. Psychosocial treatment methods such as individual psychotherapy, group psychotherapy, family therapy, cognitive behavior therapy, cue exposure therapy, 12-step facilitation therapy, self-help group therapy, and community-based treatment have been carried out to treat chronic alcoholism in Korea. However, current alcohol treatment system in Korea is not integrative compared to that in the United States. To establish the treatment system, it is important to set up an independent governmental administration on alcohol abuse, to secure experts on alcoholism, and to conduct outpatient alcoholism treatment programs and facilities in an open system including some form of continuing care.

Development of high electrical resistance persistent current switch for high speed energization system

International Nuclear Information System (INIS)

Jizo, Y.; Furuta, Y.; Nakashima, H.

1986-01-01

Japanese National Railways is now developing a superconducting magnetically-levitated train system. A persistent current switch is incorporated in the super-conducting magnet used in the magnetically-levitated train. In recent years, the switch has been required to have higher electrical resistance during its off-state in order to realize the high speed energization/de-energization system of the superconducting magnets. The system aims to decrease evaporation volume of liquid helium during the energization/de-energization of the magnet, by means of energizing the superconducting magnet with high current increasing/decreasing rate. Consequently, it would be possible to decrease the dependence of the on-board magnet system upon the ground cooling system. Through the development of a stable superconductive wire material and a coil structure for the persistent current switch using many small model switches which were produced in order to improve their current carrying capacities, the authors have succeeded in manufacturing the high electrical resistance persistent current switch whose electrical resistance was 5 ohms. The switch, of cylindrical shape, has a diameter of about 100mm, a length of about 100mm. These 5 ohm PCSs are now functioning in stable conditions being incorporated in the superconducting magnets of No.2 vehicle of MLU001 at the JNR's Miyazaki test track. Further, the authors are now developing the PCS of still higher resistance values, such as 50 ohms, through studies for stabilization in structural aspects of the winding and obtaining results therefrom

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.

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

International Nuclear Information System (INIS)

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

2015-01-01

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.

Direct determination of IMF B-Y-related cusp current systems, using SuperDARN radar and multiple ground magnetometer data: A link to theory on cusp current origin

DEFF Research Database (Denmark)

Amm, O.; Engebretson, M.J.; Greenwald, R.A.

1999-01-01

, respectively, with magnitudes of around 0.5 A/km(2). The geometry of the current system resembles a DPY current system [Friis-Christensen and Wilhjelm, 1975]. Using our results, we test alternative theories on cusp current origin that lead to different predictions of the relative location of the cusp current...... are caused by a rotational discontinuity of the magnetic field at the magnetopause. In contrast, the idea of Clauer and Banks [1986] that a mapping of the solar wind E-z component to the ionosphere is responsible for the cusp current system is not supported....... system with respect to the open-closed field line boundary. The location of this boundary is inferred from DMSP F10 satellite data. The center of our resulting current system is located clearly poleward of the open-closed field line boundary, thus favoring the idea of Lee et al. [1985] that the cusp FACs...

Patterns and processes in the California Current System

Science.gov (United States)

Checkley, David M., Jr.; Barth, John A.

2009-12-01

The California Current System (CCS) is forced by the distribution of atmospheric pressure and associated winds in relation to the west coast of North America. In this paper, we begin with a simplified case of winds and a linear coast, then consider variability characteristic of the CCS, and conclude by considering future change. The CCS extends from the North Pacific Current (∼50°N) to off Baja California, Mexico (∼15-25°N) with a major discontinuity at Point Conception (34.5°N). Variation in atmospheric pressure affects winds and thus upwelling. Coastal, wind-driven upwelling results in nutrification and biological production and a southward coastal jet. Offshore, curl-driven upwelling results in a spatially large, productive habitat. The California Current flows equatorward and derives from the North Pacific Current and the coastal jet. Dominant modes of spatial and temporal variability in physical processes and biological responses are discussed. High surface production results in deep and bottom waters depleted in oxygen and enriched in carbon dioxide. Fishing has depleted demersal stocks more than pelagic stocks, and marine mammals, including whales, are recovering. Krill, squid, and micronekton are poorly known and merit study. Future climate change will differ from past change and thus prediction of the CCS requires an understanding of its dynamics. Of particular concern are changes in winds, stratification, and ocean chemistry.

High beam current shut-off systems in the APS linac and low energy transfer line

International Nuclear Information System (INIS)

Wang, X.; Knott, M.; Lumpkin, A.

1994-01-01

Two independent high beam current shut-off current monitoring systems (BESOCM) have been installed in the APS linac and the low energy transport line to provide personnel safety protection in the event of acceleration of excessive beam currents. Beam current is monitored by a fast current transformer (FCT) and fully redundant supervisory circuits connected to the Access Control Interlock System (ACIS) for beam intensity related shutdowns of the linac. One FCT is located at the end of the positron linac and the other in the low energy transport line, which directs beam to the positron accumulator ring (PAR). To ensure a high degree of reliability, both systems employ a continuous self-checking function, which injects a test pulse to a single-turn test winding after each ''real'' beam pulse to verify that the system is fully functional. The system is designed to be fail-safe for all possible system faults, such as loss of power, open or shorted signal or test cables, loss of external trigger, malfunction of gated integrator, etc. The system has been successfully commissioned and is now a reliable part of the total ACIS

What the Current System Development Trends tell us about Systems Development Methodologies: Toward explaining SSDAM, Agile and IDEF0 Methodologies

Directory of Open Access Journals (Sweden)

Abdulla F. Ally

2015-03-01

Full Text Available Systems integration, customization and component based development approach are of increasing attention. This trend facilitates the research attention to also focus on systems development methodologies. The availability of systems development tools, rapid change in technologies, evolution of mobile computing and the growth of cloud computing have necessitated a move toward systems integration and customization rather than developing systems from scratch. This tendency encourages component based development and discourages traditional systems development approach. The paper presents and evaluates SSADM, IDEF0 and Agile systems development methodologies. More specifically, it examines how they fit or not fit into the current competitive market of systems development. In the view of this perspective, it is anticipated that despite of its popularity, SSADM methodology is becoming obsolete while Agile and IDEF0 methodologies are still gaining acceptance in the current competitive market of systems development. The present study more likely enrich our understanding of the systems development methodologies concepts and draw attention regarding where the current trends in system development are heading.

Electric machine and current source inverter drive system

Science.gov (United States)

Hsu, John S

2014-06-24

A drive system includes an electric machine and a current source inverter (CSI). This integration of an electric machine and an inverter uses the machine's field excitation coil for not only flux generation in the machine but also for the CSI inductor. This integration of the two technologies, namely the U machine motor and the CSI, opens a new chapter for the component function integration instead of the traditional integration by simply placing separate machine and inverter components in the same housing. Elimination of the CSI inductor adds to the CSI volumetric reduction of the capacitors and the elimination of PMs for the motor further improve the drive system cost, weight, and volume.

Matrix- and tensor-based recommender systems for the discovery of currently unknown inorganic compounds

Science.gov (United States)

Seko, Atsuto; Hayashi, Hiroyuki; Kashima, Hisashi; Tanaka, Isao

2018-01-01

Chemically relevant compositions (CRCs) and atomic arrangements of inorganic compounds have been collected as inorganic crystal structure databases. Machine learning is a unique approach to search for currently unknown CRCs from vast candidates. Herein we propose matrix- and tensor-based recommender system approaches to predict currently unknown CRCs from database entries of CRCs. Firstly, the performance of the recommender system approaches to discover currently unknown CRCs is examined. A Tucker decomposition recommender system shows the best discovery rate of CRCs as the majority of the top 100 recommended ternary and quaternary compositions correspond to CRCs. Secondly, systematic density functional theory (DFT) calculations are performed to investigate the phase stability of the recommended compositions. The phase stability of the 27 compositions reveals that 23 currently unknown compounds are newly found to be stable. These results indicate that the recommender system has great potential to accelerate the discovery of new compounds.

Energy use in pig production: an examination of current Iowa systems.

Science.gov (United States)

Lammers, P J; Kenealy, M D; Kliebenstein, J B; Harmon, J D; Helmers, M J; Honeyman, M S

2012-03-01

This paper compares energy use for different pig production systems in Iowa, a leader in US swine production. Pig production systems include not only the growth and performance of the pigs, but also the supporting infrastructure of pig production. This supporting infrastructure includes swine housing, facility management, feedstuff provision, swine diets, and manure management. Six different facility type × diet formulation × cropping sequence scenarios were modeled and compared. The baseline system examined produces 15,600 pigs annually using confinement facilities and a corn-soybean cropping sequence. Diet formulations for the baseline system were corn-soybean meal diets that included the synthetic AA l-lysine and exogenous phytase. The baseline system represents the majority of current US pork production in the Upper Midwest, where most US swine are produced. This system was found to require 744.6 MJ per 136-kg market pig. An alternative system that uses bedded hoop barns for grow-finish pigs and gestating sows would require 3% less (720.8 MJ) energy per 136-kg market pig. When swine production systems were assessed, diet type and feed ingredient processing were the major influences on energy use, accounting for 61 and 79% of total energy in conventional and hoop barn-based systems, respectively. Improving feed efficiency and better matching the diet formulation with the thermal environment and genetic potential are thus key aspects of reducing energy use by pig production, particularly in a hoop barn-based system. The most energy-intensive aspect of provisioning pig feed is the production of synthetic N for crop production; thus, effectively recycling manure nutrients to cropland is another important avenue for future research. Almost 25% of energy use by a conventional farrow-to-finish pig production system is attributable to operation of the swine buildings. Developing strategies to minimize energy use for heating and ventilation of swine buildings while

Assembly, installation and commissioning of the JET-EP Halo Current Sensors system

International Nuclear Information System (INIS)

Peruzzo, S.; Grando, L.; Pomaro, N.; Sonato, P.; Fullard, K.; Huntley, S.; Lam, N.; Riccardo, V.

2006-01-01

The Halo Current Sensors (HCS) system has been developed under the JET-EP enhancement programme, to allow a more detailed study of the Halo Currents flowing in the upper part of the JET vessel. A better understanding of the origin, distribution and scaling of Halo Currents in tokamaks is one of the critical issues for any next step device, like the ITER project, in particular for the design of the plasma facing components and for a reliable plasma operation at high performances. The HCS system includes four sets of probes located in four octants equally spaced along the toroidal coordinate, each containing up to eight Rogowski coils and two toroidal field pick-up coils. The Rogowski coils are designed to directly measure the current flowing through the tiles of the upper dump plate, whereas the toroidal field pick-up coils are conceived to give an estimate the total poloidal Halo Current flowing through the first wall structures. The HCS system was installed in the JET vacuum vessel in March 2005 during the 2004/05 Shutdown and started the acquisition of signals during the restart phase of the machine in autumn 2005. This paper will highlight and discuss the critical aspects and the lessons learned during the final phase of the procurement of the system; the in-vessel installation, accomplished by means of remote handling system, and the pre-commissioning tests executed on the system will be described in detail. The paper will then focus on the analysis and interpretation of the data collected during the functional commissioning of the new system, carried out during the restart phase of the machine preceding the experimental campaigns. Since the beginning of operation the HCS signals showed the effects of several noise sources, increased by the low sensitivity of the probes, due to design geometrical constraints. The expected pick-up of stray magnetic fields was quite easily compensated through a correlation with other existing magnetic diagnostics. Moreover the

Progress and plans for the EnCurrent power generation system

Energy Technology Data Exchange (ETDEWEB)

Bear, C. [New Energy Corp. Inc., Calgary, AB (Canada)

2008-07-01

This presentation discussed a new vertical axis hydro turbine designed by New Energy Corporation. The EnCurrent turbine design was based on the Darrieus wind turbine, and suited for use in rivers, irrigation canals, industrial outflows, and tidal current applications. The turbine has a flexible deployment configuration with a variable aspect ratio. Designs for the turbine were initiated in fresh water applications, and the size of the equipment was increased to include tidal applications and large river arrays after the technology was proven. A study has demonstrated that use of the turbines in Canada's canal systems would result in significant annual power generation revenues. The use of smaller turbine systems can provide indirect sales to owners through local resellers, while larger systems can provide power or additional revenues for utilities, large cooperatives, and project developers. Case studies of small turbine installations were provided, as well as case studies of turbines used by larger commercial plants. The presentation also discussed several large projects recently undertaken by the company, including the $6.5 million Canoe pass installation. tabs., figs.

Design and initial tests of beam current monitoring systems for the APS transport lines

International Nuclear Information System (INIS)

Wang, Xucheng.

1992-01-01

The non-intercepting beam current monitoring systems suitable for a wide, range of beam parameters have been developed for the Advanced Photon Source (APS) low energy transport lines and high energy transport line. The positron or electron beam pulse in the transport lines wig have peak beam currents ranging from 8 mA to 29 A with pulse widths varying from 120 ps to 30 ns and pulse repetition rates from 2 Hz to 60 Hz. The peak beam current or total beam charge is measured with the fast or integrating current transformer, respectively, manufactured by Bergoz. In-house high speed beam signal processing electronics provide a DC level output proportional to the peak current or total charge for the digitizer input. The prototype systems were tested on the linacs which have beam pulse structures similar to that of the APS transport lines. This paper describes the design of beam signal processing electronics and grounding and shielding methods for current transformers. The results of the initial operations are presented. A short introduction on the preliminary design of current monitoring systems for the APS rings is also included

Large fluctuations of the macroscopic current in diffusive systems: a numerical test of the additivity principle.

Science.gov (United States)

Hurtado, Pablo I; Garrido, Pedro L

2010-04-01

Most systems, when pushed out of equilibrium, respond by building up currents of locally conserved observables. Understanding how microscopic dynamics determines the averages and fluctuations of these currents is one of the main open problems in nonequilibrium statistical physics. The additivity principle is a theoretical proposal that allows to compute the current distribution in many one-dimensional nonequilibrium systems. Using simulations, we validate this conjecture in a simple and general model of energy transport, both in the presence of a temperature gradient and in canonical equilibrium. In particular, we show that the current distribution displays a Gaussian regime for small current fluctuations, as prescribed by the central limit theorem, and non-Gaussian (exponential) tails for large current deviations, obeying in all cases the Gallavotti-Cohen fluctuation theorem. In order to facilitate a given current fluctuation, the system adopts a well-defined temperature profile different from that of the steady state and in accordance with the additivity hypothesis predictions. System statistics during a large current fluctuation is independent of the sign of the current, which implies that the optimal profile (as well as higher-order profiles and spatial correlations) are invariant upon current inversion. We also demonstrate that finite-time joint fluctuations of the current and the profile are well described by the additivity functional. These results suggest the additivity hypothesis as a general and powerful tool to compute current distributions in many nonequilibrium systems.

The Chern-Simons Current in Systems of DNA-RNA Transcriptions

Science.gov (United States)

Capozziello, Salvatore; Pincak, Richard; Kanjamapornkul, Kabin; Saridakis, Emmanuel N.

2018-04-01

A Chern-Simons current, coming from ghost and anti-ghost fields of supersymmetry theory, can be used to define a spectrum of gene expression in new time series data where a spinor field, as alternative representation of a gene, is adopted instead of using the standard alphabet sequence of bases $A, T, C, G, U$. After a general discussion on the use of supersymmetry in biological systems, we give examples of the use of supersymmetry for living organism, discuss the codon and anti-codon ghost fields and develop an algebraic construction for the trash DNA, the DNA area which does not seem active in biological systems. As a general result, all hidden states of codon can be computed by Chern-Simons 3 forms. Finally, we plot a time series of genetic variations of viral glycoprotein gene and host T-cell receptor gene by using a gene tensor correlation network related to the Chern-Simons current. An empirical analysis of genetic shift, in host cell receptor genes with separated cluster of gene and genetic drift in viral gene, is obtained by using a tensor correlation plot over time series data derived as the empirical mode decomposition of Chern-Simons current.

Velocity of small-scale auroral ionospheric current systems over ...

Indian Academy of Sciences (India)

At the latter times, triangulation with 3 uxgate magnetometers located at the vertices of a suitable triangle provides a means of monitoring mobile auroral ionospheric current systems over Maitri. The spacing between the magnetometers is typically kept at 75-200 km, keeping in mind the scale-sizes of ∼100 km for these ...

Modeling and control of the output current of a Reformed Methanol Fuel Cell system

DEFF Research Database (Denmark)

Justesen, Kristian Kjær; Andreasen, Søren Juhl; Pasupathi, Sivakumar

2015-01-01

In this work, a dynamic Matlab SIMULINK model of the relationship between the fuel cell current set point of a Reformed Methanol Fuel Cell system and the output current of the system is developed. The model contains an estimated fuel cell model, based on a polarization curve and assumed first order...... dynamics, as well as a battery model based on an equivalent circuit model and a balance of plant power consumption model. The models are tuned with experimental data and verified using a verification data set. The model is used to develop an output current controller which can control the charge current...... of the battery. The controller is a PI controller with feedforward and anti-windup. The performance of the controller is tested and verified on the physical system....

Assembly, installation and commissioning of the new halo current sensors system for JET

International Nuclear Information System (INIS)

Peruzzo, S.; Fullard, K.; Grando, L.; Huntley, S.; Lam, N.; Pomaro, N.; Riccardo, V.; Sonato, P.

2007-01-01

This paper presents the status of the halo current sensors (HCS) diagnostic enhancement project for JET. The HCS system includes four sets of probes located in four octants equally spaced along the toroidal coordinate, with a total of 24 Rogowski coils and 5 toroidal field pick-up coils. These sensors are meant to provide a measurement of the current flowing through each single tile of the upper dump plate and an estimate of the total poloidal halo current flowing through the first wall structures. The HCS system was installed in the JET vacuum vessel in March 2005 during the 2004/2005 shutdown and the acquisition of signals started during the restart phase of the machine in autumn 2005. This paper firstly summarises the critical aspects encountered during the final phase of the procurement of the system and the in-vessel installation, which was accomplished using the remote handling system. The paper then focuses on the analysis and interpretation of the data collected during the functional commissioning of the new system, carried out during the restart phase of the machine preceding the experimental campaigns

Comparative study on current trading system and online trading: the ...

African Journals Online (AJOL)

Comparative study on current trading system and online trading: the case of ... of online trading and factors affecting its feasibility of implementation in ECX. ... The study found that there is significant capacity problem with major skills gap with ...

Design of the power supply system for the plasma current modulation on J-TEXT tokamak

Energy Technology Data Exchange (ETDEWEB)

Zhang, M.; Shao, J.; Ma, S.X., E-mail: mashaoxiang@hust.edu.cn; Liang, X.; Yu, K.X.; Pan, Y.

2016-10-15

Highlights: • A modification scheme of heating field power supply system for plasma current modulation. • High-power fast control power supply with multilevel cascade circuit. • Restraining circulating current with coupled inductors in cyclic symmetric structure. - Abstract: In order to further study the influence of current modulation parameters on suppressing tearing instability, the plasma current should be modulated in a wider range. So a modification scheme is designed to improve the performance of ohmic heating power supply system on J-TEXT tokamak. A multilevel cascade circuit with carrier phase-shifted PWM technique has been proposed. Coupled inductors are connected in the form of cyclic symmetry to restrain the circulating current caused by multiple paralleled branches. The simulation proves this proposed current modulation power supply system matches output requirement and achieves good current sharing effect. Finally, a prototype is designed, and the experiment results can verify the correctness of the simulation model well.

The targeted heating and current drive applications for the ITER electron cyclotron system

Energy Technology Data Exchange (ETDEWEB)

Henderson, M.; Darbos, C.; Gandini, F.; Gassmann, T.; Loarte, A.; Omori, T.; Purohit, D. [ITER Organization, Route de Vinon-sur-Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); Saibene, G.; Gagliardi, M. [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Farina, D.; Figini, L. [Istituto di Fisica del Plasma CNR, 20125 Milano (Italy); Hanson, G. [US ITER Project Office, ORNL, 1055 Commerce Park, PO Box 2008, Oak Ridge, Tennessee 37831 (United States); Poli, E. [Max-Planck-Institut für Plasmaphysik, D-85748 Garching (Germany); Takahashi, K. [Japan Atomic Energy Agency (JAEA), Naka, Ibaraki 311-0193 (Japan)

2015-02-15

A 24 MW Electron Cyclotron (EC) system operating at 170 GHz and 3600 s pulse length is to be installed on ITER. The EC plant shall deliver 20 MW of this power to the plasma for Heating and Current Drive (H and CD) applications. The EC system is designed for plasma initiation, central heating, current drive, current profile tailoring, and Magneto-hydrodynamic control (in particular, sawteeth and Neo-classical Tearing Mode) in the flat-top phase of the plasma. A preliminary design review was performed in 2012, which identified a need for extended application of the EC system to the plasma ramp-up, flattop, and ramp down phases of ITER plasma pulse. The various functionalities are prioritized based on those applications, which can be uniquely addressed with the EC system in contrast to other H and CD systems. An initial attempt has been developed at prioritizing the allocated H and CD applications for the three scenarios envisioned: ELMy H-mode (15 MA), Hybrid (∼12 MA), and Advanced (∼9 MA) scenarios. This leads to the finalization of the design requirements for the EC sub-systems.

Current lead thermal analysis code 'CURRENT'

International Nuclear Information System (INIS)

Yamaguchi, Masahito; Tada, Eisuke; Shimamoto, Susumu; Hata, Kenichiro.

1985-08-01

Large gas-cooled current lead with the capacity more than 30 kA and 22 kV is required for superconducting toroidal and poloidal coils for fusion application. The current lead is used to carry electrical current from the power supply system at room temperature to the superconducting coil at 4 K. Accordingly, the thermal performance of the current lead is significantly important to determine the heat load requirements of the coil system at 4 K. Japan Atomic Energy Research Institute (JAERI) has being developed the large gas-cooled current leads with the optimum condition in which the heat load is around 1 W per 1 kA at 4 K. In order to design the current lead with the optimum thermal performances, JAERI developed thermal analysis code named as ''CURRENT'' which can theoretically calculate the optimum geometric shape and cooling conditions of the current lead. The basic equations and the instruction manual of the analysis code are described in this report. (author)

Mediterranea Forecasting System: a focus on wave-current coupling

Science.gov (United States)

Clementi, Emanuela; Delrosso, Damiano; Pistoia, Jenny; Drudi, Massimiliano; Fratianni, Claudia; Grandi, Alessandro; Pinardi, Nadia; Oddo, Paolo; Tonani, Marina

2016-04-01

The Mediterranean Forecasting System (MFS) is a numerical ocean prediction system that produces analyses, reanalyses and short term forecasts for the entire Mediterranean Sea and its Atlantic Ocean adjacent areas. MFS became operational in the late 90's and has been developed and continuously improved in the framework of a series of EU and National funded programs and is now part of the Copernicus Marine Service. The MFS is composed by the hydrodynamic model NEMO (Nucleus for European Modelling of the Ocean) 2-way coupled with the third generation wave model WW3 (WaveWatchIII) implemented in the Mediterranean Sea with 1/16 horizontal resolution and forced by ECMWF atmospheric fields. The model solutions are corrected by the data assimilation system (3D variational scheme adapted to the oceanic assimilation problem) with a daily assimilation cycle, using a background error correlation matrix varying seasonally and in different sub-regions of the Mediterranean Sea. The focus of this work is to present the latest modelling system upgrades and the related achieved improvements. In order to evaluate the performance of the coupled system a set of experiments has been built by coupling the wave and circulation models that hourly exchange the following fields: the sea surface currents and air-sea temperature difference are transferred from NEMO model to WW3 model modifying respectively the mean momentum transfer of waves and the wind speed stability parameter; while the neutral drag coefficient computed by WW3 model is passed to NEMO that computes the turbulent component. In order to validate the modelling system, numerical results have been compared with in-situ and remote sensing data. This work suggests that a coupled model might be capable of a better description of wave-current interactions, in particular feedback from the ocean to the waves might assess an improvement on the prediction capability of wave characteristics, while suggests to proceed toward a fully

Brake Performance Analysis of ABS for Eddy Current and Electrohydraulic Hybrid Brake System

Directory of Open Access Journals (Sweden)

Ren He

2013-01-01

Full Text Available This paper introduces an eddy current and electro-hydraulic hybrid brake system to solve problems such as wear, thermal failure, and slow response of traditional vehicle brake system. Mathematical model was built to calculate the torque of the eddy current brake system and hydraulic brake system and analyze the braking force distribution between two types of brake systems. A fuzzy controller on personal computer based on LabVIEW and Matlab was designed and a set of hardware in the loop system was constructed to validate and analyze the performance of the hybrid brake system. Through lots of experiments on dry and wet asphalt roads, the hybrid brake system achieves perfect performance on the experimental bench, the hybrid system reduces abrasion and temperature of the brake disk, response speed is enhanced obviously, fuzzy controller keeps high utilization coefficient due to the optimal slip ratio regulation, and the total brake time has a smaller decrease than traditional hydraulic brake system.

Design of a microscopic electrical impedance tomography system using two current injections

International Nuclear Information System (INIS)

Liu, Qin; Oh, Tong In; Wi, Hun; Woo, Eung Je; Lee, Eun Jung; Seo, Jin Keun

2011-01-01

We describe a novel design of a microscopic electrical impedance tomography (micro-EIT) system for long-term noninvasive monitoring of cell or tissue cultures. The core of the micro-EIT system is a sample container including two pairs of current-injection electrodes and 360 voltage-sensing electrodes. In designing the container, we took advantage of a hexagonal structure with fixed dimensions and electrode configuration. This eliminated technical difficulties related to the unknown irregular boundary geometry of an imaging object in conventional medical EIT. Attaching a pair of large current-injection electrodes fully covering the left and right sides of the hexagonal container, we generated uniform parallel current density inside the container filled with saline. The 360 voltage-sensing electrodes were placed on the front, bottom and back sides of the hexagonal container in three sets of 8 × 15 arrays with equal gaps between them. We measured voltage differences between all neighboring pairs along the direction of the parallel current pathway. For the homogeneous container, all measured voltages must be the same since the voltage changes linearly along that direction. Any anomaly in the container perturbed the current pathways and therefore equipotential lines to produce different differential voltage data. For conductivity image reconstructions, we adopted a lately developed image reconstruction algorithm for this electrode configuration to first produce projected conductivity images on the front, bottom and back sides. Using a backprojection method, we reconstructed three-dimensional conductivity images from those projection images. To improve the image quality and also to meet the mathematical requirement on the uniqueness of a reconstructed image, we used a second pair of thin and long current-injection electrodes located at the middle of the front and back sides. This paper describes the design and construction of such a micro-EIT system with experimental

Time-dependent current-density functional theory for generalized open quantum systems.

Science.gov (United States)

Yuen-Zhou, Joel; Rodríguez-Rosario, César; Aspuru-Guzik, Alán

2009-06-14

In this article, we prove the one-to-one correspondence between vector potentials and particle and current densities in the context of master equations with arbitrary memory kernels, therefore extending time-dependent current-density functional theory (TD-CDFT) to the domain of generalized many-body open quantum systems (OQS). We also analyse the issue of A-representability for the Kohn-Sham (KS) scheme proposed by D'Agosta and Di Ventra for Markovian OQS [Phys. Rev. Lett. 2007, 98, 226403] and discuss its domain of validity. We suggest ways to expand their scheme, but also propose a novel KS scheme where the auxiliary system is both closed and non-interacting. This scheme is tested numerically with a model system, and several considerations for the future development of functionals are indicated. Our results formalize the possibility of practising TD-CDFT in OQS, hence expanding the applicability of the theory to non-Hamiltonian evolutions.

Development of high current beam ns pulsed system

CERN Document Server

Shen Guan Ren; Gao Fu; Guan Xia Ling; LiuNaiYi

2001-01-01

The development of high current beam ns pulsed system of CPNG and its characteristic, main technological performance and application are introduced. Firstly, important parameters of the system are calculated using theoretical model, the design requirements of some important parts are understood. Some mistakes in physics conception are corrected. Second, the chopper is designed for parallel plate deflector, chopping aperture and sine wave voltage sweeping device. It is emphasized that the conception of parallel plate load impedance is the capacitance load, but not the 50 ohm load impedance. The dynamic capacitance value has been measured. The output emphasizes the output voltage amplitude, but not the output power for sweeping device. The display system of output sweeping voltage was set up and it is sure that the maximum output voltage(V-V) is >=4000 V. The klystron buncher are re-designed. It is emphasized to overcome difficulty of support high voltage electrode in the klystron and insulator of input sine wa...

An automatic monitoring system of leak current for testing TGC detectors based on LabVIEW

International Nuclear Information System (INIS)

Feng Cunfeng; Lu Taiguo; Yan Zhen; Wang Suojie; Zhu Chengguang; Sun Yansheng; He Mao

2005-01-01

An automatic monitoring system of leak current for testing TGC detectors with high voltage was set up by using the graphic LabVIEW platform and NI 4351 data acquisition card. The leak current was automatically monitored and recorded with this system, the time and the value of the leak current were showed instantly. Good efficiency and precision of monitoring were obtained. (authors)

Pulsed eddy current inspection system for nondestructive examination of irradiated fuel rods

International Nuclear Information System (INIS)

Yancey, M.E.

1979-01-01

An inspection system has been developed for nondestructive examination of irradiated fuel rods utilizing pulsed eddy current techniques. The system employs an encircling type pulsed eddy current transducer capable of sensing small defects located on both the inner and outer diameter fuel rod surfaces during a single scan. Pulsed eddy current point probes are used to provide fuel rod wall thikness data and an indication of radial defect location. Two linear variable differential transformers are used to provide information on fuel rod diameter variation. A microprocessor based control system is used to automatically scan fuel rods up to 4.06 meters in length at predetermined radial locations. Defects as small as 0.005 cm deep by 0.254 cm long by 0.005 cm wide have been detected on outside diameter surfaces of a 1.43 cm outside diameter fuel rod cladding with a 0.094 cm wall thickness and 0.010 cm deep by 0.254 cm long by 0.005 cm wide on the inside diameter surface

Methodology for simulation of geomagnetically induced currents in power systems

Directory of Open Access Journals (Sweden)

Boteler David

2014-07-01

Full Text Available To assess the geomagnetic hazard to power systems it is useful to be able to simulate the geomagnetically induced currents (GIC that are produced during major geomagnetic disturbances. This paper examines the methodology used in power system analysis and shows how it can be applied to modelling GIC. Electric fields in the area of the power network are used to determine the voltage sources or equivalent current sources in the transmission lines. The power network can be described by a mesh impedance matrix which is combined with the voltage sources to calculate the GIC in each loop. Alternatively the power network can be described by a nodal admittance matrix which is combined with the sum of current sources into each node to calculate the nodal voltages which are then used to calculate the GIC in the transmission lines and GIC flowing to ground at each substation. Practical calculations can be made by superposition of results calculated separately for northward and eastward electric fields. This can be done using magnetic data from a single observatory to calculate an electric field that is a uniform approximation of the field over the area of the power system. It is also shown how the superposition of results can be extended to use data from two observatories: approximating the electric field by a linear variation between the two observatory locations. These calculations provide an efficient method for simulating the GIC that would be produced by historically significant geomagnetic storm events.

Single phase cascaded H5 inverter with leakage current elimination for transformerless photovoltaic system

DEFF Research Database (Denmark)

Guo, Xiaoqiang; Jia, X.; Lu, Z.

2016-01-01

Leakage current reduction is one of the important issues for the transformelress PV systems. In this paper, the transformerless single-phase cascaded H-bridge PV inverter is investigated. The common mode model for the cascaded H4 inverter is analyzed. And the reason why the conventional cascade H4...... inverter fails to reduce the leakage current is clarified. In order to solve the problem, a new cascaded H5 inverter is proposed to solve the leakage current issue. Finally, the experimental results are presented to verify the effectiveness of the proposed topology with the leakage current reduction...... for the single-phase transformerless PV systems....

Stator Current Harmonic Reduction in a Novel Half Quasi-Z-Source Wind Power Generation System

Directory of Open Access Journals (Sweden)

Shoudao Huang

2016-09-01

Full Text Available The generator stator current gets distorted with unacceptable levels of total harmonic distortion (THD because impedance-source wind power generation systems use three-phase diode rectifiers. The stator current harmonics will cause increasing losses and torque ripple, which reduce the efficiency and stability of the system. This paper proposes a novel half quasi-Z-source inverter (H-qZSI for grid-connected wind power generation systems, which can reduce the generator stator current harmonics a great deal. When H-qZSI operates in the shoot-through zero state, the derivative of the generator stator current is only determined by the instantaneous value of the generator stator voltage, so the nonlinear relationship between generator stator current and stator voltage is improved compared with the traditional impedance-source inverter. Theoretically, it is indicated that the stator current harmonics can be reduced effectively by means of the proposed H-qZSI. Finally, simulation and experimental results are given to verify the theoretical analysis.

Collisionless effects on beam-return current systems in solar flares

Science.gov (United States)

Vlahos, L.; Rowland, H. L.

1985-01-01

A theoretical study of the beam-return current system (BRCS) in solar flares shows that the precipitating electrons modify the way in which the return current (RC) is carried by the background plasma. In particular it is found that the RC is not carried by the bulk of the electrons but by a small number of high-velocity electrons. For beam/plasma densities exceeding approximately 0.001, this can reduce the effects of collisions and heating by the RC. For higher-density beams, where the RC could be unstable to current-driven instabilities, the effects of strong turbulence anomalous resistivity prevent the appearance of such instabilities. The main conclusion is that the BRCS is interconnected, and that the beam-generated strong turbulence determines how the RC is carried.

Current reprogramming systems in regenerative medicine: from somatic cells to induced pluripotent stem cells.

Science.gov (United States)

Hu, Chenxia; Li, Lanjuan

2016-01-01

Induced pluripotent stem cells (iPSCs) paved the way for research fields including cell therapy, drug screening, disease modeling and the mechanism of embryonic development. Although iPSC technology has been improved by various delivery systems, direct transduction and small molecule regulation, low reprogramming efficiency and genomic modification steps still inhibit its clinical use. Improvements in current vectors and the exploration of novel vectors are required to balance efficiency and genomic modification for reprogramming. Herein, we set out a comprehensive analysis of current reprogramming systems for the generation of iPSCs from somatic cells. By clarifying advantages and disadvantages of the current reprogramming systems, we are striding toward an effective route to generate clinical grade iPSCs.

Direct current hopping conductance in one-dimensional diagonal disordered systems

Institute of Scientific and Technical Information of China (English)

Ma Song-Shan; Xu Hui; Liu Xiao-Liang; Xiao Jian-Rong

2006-01-01

Based on a tight-binding disordered model describing a single electron band, we establish a direct current (dc) electronic hopping transport conductance model of one-dimensional diagonal disordered systems, and also derive a dc conductance formula. By calculating the dc conductivity, the relationships between electric field and conductivity and between temperature and conductivity are analysed, and the role played by the degree of disorder in electronic transport is studied. The results indicate the conductivity of systems decreasing with the increase of the degree of disorder, characteristics of negative differential dependence of resistance on temperature at low temperatures in diagonal disordered systems, and the conductivity of systems decreasing with the increase of electric field, featuring the non-Ohm's law conductivity.

Current and emerging lipid-based systems for transdermal drug delivery.

Science.gov (United States)

Singla, Sumeet K; Sachdeva, Vishal

2015-01-01

Developing a transdermal drug delivery system is a challenging task considering the selective permeability of the skin and the physicochemical properties the drug must possess to permeate through the skin. Lipid-based drug delivery systems have contributed a great deal in this direction in the last few decades, and thereby have helped to expand the range of therapeutic molecules that can be delivered through the skin in a safe and effective manner. Additionally, vesicular delivery systems such as nanoparticles and emulsions have also played important roles in providing alternative novel approaches for drug delivery. In this article, we will discuss some of the current and future lipid-based systems for transdermal drug delivery along with the associated challenges.

IMPROVING MODEL OF CHANNEL AIRBORN ELECTRICAL POWER SYSTEM OF ALTERNATING CURRENT

Directory of Open Access Journals (Sweden)

Yu. P. Artemenko

2015-01-01

Full Text Available This article is devoted to math modeling of channel of alternating current airborne electrical power-supply system. Mathematical modeling of generator, voltage regulator, constant speed drive is considered.

Galvanically Decoupled Current Source Modules for Multi-Channel Bioimpedance Measurement Systems

Directory of Open Access Journals (Sweden)

Roman Kusche

2017-10-01

Full Text Available Bioimpedance measurements have become a useful technique in the past several years in biomedical engineering. Especially, multi-channel measurements facilitate new imaging and patient monitoring techniques. While most instrumentation research has focused on signal acquisition and signal processing, this work proposes the design of an excitation current source module that can be easily implemented in existing or upcoming bioimpedance measurement systems. It is galvanically isolated to enable simultaneous multi-channel bioimpedance measurements with a very low channel-coupling. The system is based on a microcontroller in combination with a voltage-controlled current source circuit. It generates selectable sinusoidal excitation signals between 0.12 and 1.5 mA in a frequency range from 12 to 250 kHz, whereas the voltage compliance range is ±3.2 V. The coupling factor between two current sources, experimentally galvanically connected with each other, is measured to be less than −48 dB over the entire intended frequency range. Finally, suggestions for developments in the future are made.

Design and Test of a Thermal Triggered Persistent Current System using High Temperature Superconducting Tapes

Energy Technology Data Exchange (ETDEWEB)

Park, Dong Keun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Kang, Hyoungku [Electro-Mechanical Research Institute, Hyundai Heavy Industries, Yongin (Korea, Republic of); Ahn, Min Cheol [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yang, Seong Eun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yoon, Yong Soo [Department of Electrical Engineering, Ansan College of Technology, 671 Choji-Dong, Danwon-Gu, Ansan, 425-792 (Korea, Republic of); Lee, Sang Jin [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Ko, Tae Kuk [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of)

2006-06-01

A superconducting magnet which is operated in persistent current mode in SMES, NMR, MRI and MAGLEV has many advantages such as high uniformity of magnetic field and reduced thermal loss. A high temperature superconducting (HTS) persistent current switch (PCS) system was designed and tested in this research. The HTS PCS was optimally designed using two different HTS tapes, second generation coated conductor (CC) HTS tape and Bi-2223 HTS tape by the finite element method (FEM) in thermal quench characteristic view. The CC tape is more prospective applicable wire in these days for its high n value and critical current independency from external magnetic field than Bi-2223 tape. Also a prototype PCS system using Bi-2223 tape was manufactured and tested. The PCS system consists of a PCS part, a heater which induces the PCS to quench, and a superconducting magnet. The test was performed in various conditions of transport current. An initial current decay appeared when the superconducting magnet was energized in a PCS system was analyzed. This paper would be foundation of HTS PCS researches.

Improvement of automatic control system for high-speed current collectors

Science.gov (United States)

Sidorov, O. A.; Goryunov, V. N.; Golubkov, A. S.

2018-01-01

The article considers the ways of regulation of pantographs to provide quality and reliability of current collection at high speeds. To assess impact of regulation was proposed integral criterion of the quality of current collection, taking into account efficiency and reliability of operation of the pantograph. The study was carried out using mathematical model of interaction of pantograph and catenary system, allowing to assess contact force and intensity of arcing at the contact zone at different movement speeds. The simulation results allowed us to estimate the efficiency of different methods of regulation of pantographs and determine the best option.

Design and implementation of predictive filtering system for current reference generation of active power filter

Energy Technology Data Exchange (ETDEWEB)

Kilic, Tomislav; Milun, Stanko; Petrovic, Goran [FESB University of Split, Faculty of Electrical Engineering, Machine Engineering and Naval Architecture, R. Boskovica bb, 21000, Split (Croatia)

2007-02-15

The shunt active power filters are used to attenuate the harmonic currents in power systems by injecting equal but opposite compensating currents. Successful control of the active filters requires an accurate current reference. In this paper the current reference determination based on predictive filtering structure is presented. Current reference was obtained by taking the difference of load current and its fundamental harmonic. For fundamental harmonic determination with no time delay a combination of digital predictive filter and low pass filter is used. The proposed method was implemented on a laboratory prototype of a three-phase active power filter. The algorithm for current reference determination was adapted and implemented on DSP controller. Simulation and experimental results show that the active power filter with implemented predictive filtering structure gives satisfactory performance in power system harmonic attenuation. (author)

Low-noise and high-speed photodetection system using optical feedback with a current amplification function.

Science.gov (United States)

Akiba, M

2015-09-01

A photodetection system with an optical-feedback circuit accompanied by current amplification was fabricated to minimize the drawbacks associated with a transimpedance amplifier (TIA) with a very high resistance feedback resistor. Current amplification was implemented by extracting an output light from the same light source that emitted the feedback light. The current gain corresponds to the ratio of the photocurrent created by the output light to that created by the feedback light because the feedback current value is identical to the input photocurrent value generated by an input light to be measured. The current gain has no theoretical limit. The output light was detected by a photodiode with a TIA having a small feedback resistance. The expression for the input-referred noise current of the optical-feedback photodetection system was derived, and the trade-off between sensitivity and response, which is a characteristic of TIA, was found to considerably improve. An optical-feedback photodetection system with an InGaAs pin photodiode was fabricated. The measured noise equivalent power of the system was 1.7 fW/Hz(1/2) at 10 Hz and 1.3 μm, which is consistent with the derived expression. The time response of the system was found to deteriorate with decreasing photocurrent. The 50% rise time for a light pulse input increased from 3.1 μs at a photocurrent of 10 nA to 15 μs at photocurrents below 10 pA. The bandwidth of the input-referred noise current was 7 kHz, which is consistent with rise times below 10 pA.

Eddy properties in the Southern California Current System

Science.gov (United States)

Chenillat, Fanny; Franks, Peter J. S.; Capet, Xavier; Rivière, Pascal; Grima, Nicolas; Blanke, Bruno; Combes, Vincent

2018-05-01

The California Current System (CCS) is an eastern boundary upwelling system characterized by strong eddies that are often generated at the coast. These eddies contribute to intense, long-distance cross-shelf transport of upwelled water with enhanced biological activity. However, the mechanisms of formation of such coastal eddies, and more importantly their capacity to trap and transport tracers, are poorly understood. Their unpredictability and strong dynamics leave us with an incomplete picture of the physical and biological processes at work, their effects on coastal export, lateral water exchange among eddies and their surrounding waters, and how long and how far these eddies remain coherent structures. Focusing our analysis on the southern part of the CCS, we find a predominance of cyclonic eddies, with a 25-km radius and a SSH amplitude of 6 cm. They are formed near shore and travel slightly northwest offshore for 190 days at 2 km day-1. We then study one particular, representative cyclonic eddy using a combined Lagrangian and Eulerian numerical approach to characterize its kinematics. Formed near shore, this eddy trapped a core made up of 67% California Current waters and 33% California Undercurrent waters. This core was surrounded by other waters while the eddy detached from the coast, leaving the oldest waters at the eddy's core and the younger waters toward the edge. The eddy traveled several months as a coherent structure, with only limited lateral exchange within the eddy.

Stability properties of cold blanket systems for current driven modes

International Nuclear Information System (INIS)

Ohlsson, D.

1977-12-01

The stability problem of the boundary regions of cold blanket systems with induced currents parallel to the lines of force is formulated. Particular interest is focused on two types of modes: first electrostatic modes driven by the combined effects of a transverse resistivity gradient due to a spatially non-uniform electron temperature and a longitudinal current, second electromagnetic kink like modes driven by the torque arising from a transverse current density gradient and magnetic field perturbations. It is found that the combination of various dissipative and neutral gas effects introduces strong stabilizing effects within specific parameter ranges. For particular steady-state models investigated it is shown that these effects become of importance in laboratory plasmas at relatively high densities, low temperatures and moderate magnetic field strengths. Stability diagrams based on specific steady-state cold plasma blanket models will be presented

Current statistical tools, systems and bodies concerned with safety and accident statistics.

NARCIS (Netherlands)

Koornstra, M.J.

1996-01-01

There are a wide range of differences in the methods used nationally to classify and record road accidents. The current use of road safety information systems and the few systems available for international use are discussed. Recommendations are made for a more efficient, less costly, and improved

Power system stabilization by SMES using current-fed pwm power conditioner

International Nuclear Information System (INIS)

Ishikawa, T.; Akita, S.; Taniguchi, H.; Kosho, S.; Tanaka, T.

1988-01-01

A superconducting magnetic energy storage (SMES) unit, consisted of superconducting coil and AC/DC power conditioner, can be used to suppress various kinds of instability that may cause service interruption in electric power system as it has high controllability of input/output electric power. Power system stabilizing ability of SMES has been examined experimentally by using model power system and small SMES unit. Current-fed PWM power conditioner was used to obtain maximum stabilizing effect by controlling active and reactive power simultaneously and independently. Power conditioner configuration, operating characteristics and control scheme for power system stabilization are also described. Results from experiments show the effectiveness of SMES on power system stabilization

The state of the systems of information in the companies prioritized according to the current requirementstized according to the current requirements

Directory of Open Access Journals (Sweden)

Grisel Castillo Almeida

2017-04-01

Full Text Available The necessity to maintain efficient systems of information in the prioritized companies of the territory of Pinar del Rio, Cuba, took us to carry out a diagnosis to determine the current state of the same ones and to propose group actions that congratulate the taking of decisions and the identification of the useful flows of information, to favor the organizational acting. The results of the study evidenced among other that alone 12% has an organized system of information and implemented according to the current requirements, what indicates that 88% is wasting the opportunities that offer the systems of information, also stands out the necessity to implement good practices to assure the security of the information according to the effective norms. The execution of a group of activities was approved to rise in first term the efficiency of the informative system of the study sample, with a view to continuing deepening toward the managerial intelligence.

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.

A Systematic Review of Wearable Systems for Cancer Detection: Current State and Challenges.

Science.gov (United States)

Ray, Partha Pratim; Dash, Dinesh; De, Debashis

2017-10-02

Rapid growth of sensor and computing platforms have introduced the wearable systems. In recent years, wearable systems have led to new applications across all medical fields. The aim of this review is to present current state-of-the-art approach in the field of wearable system based cancer detection and identify key challenges that resist it from clinical adoption. A total of 472 records were screened and 11 were finally included in this study. Two types of records were studied in this context that includes 45% research articles and 55% manufactured products. The review was performed per PRISMA guidelines where considerations was given to records that were published or reported between 2009 and 2017. The identified records included 4 cancer detecting wearable systems such as breast cancer (36.3%), skin cancer (36.3%), prostate cancer (18.1%), and multi-type cancer (9%). Most works involved sensor based smart systems comprising of microcontroller, Bluetooth module, and smart phone. Few demonstrated Ultra-Wide Band (i.e. UWB) antenna based wearable systems. Skin cancer detecting wearable systems were most comprehensible ones. The current works are gradually progressing with seamless integration of sensory units along with smart networking. However, they lack in cloud computing and long-range communication paradigms. Artificial intelligence and machine learning are key ports that need to be attached with current wearable systems. Further, clinical inertia, lack of awareness, and high cost are altogether pulling back the actual growth of such system. It is well comprehended that upon sincere orientation of all identified challenges, wearable systems would emerge as vital alternative to futuristic cancer detection.

Considerations on an automatic computed tomography tube current modulation system

International Nuclear Information System (INIS)

Moro, L.; Panizza, D.; D'Ambrosio, D.; Carne, I.

2013-01-01

The scope of this study was to evaluate the effects on radiation output and image noise varying the acquisition parameters with an automatic tube current modulation (ATCM) system in computed tomography (CT). Chest CT examinations of an anthropomorphic phantom were acquired using a GE LightSpeed VCT 64-slice tomograph. Acquisitions were performed using different pitch, slice thickness and noise index (NI) values and varying the orientation of the scanned projection radiograph (SPR). The radiation output was determined by the CT dose index (CTDI vol ). Image noise was evaluated measuring the standard deviation of CT numbers in several regions of interest. The radiation output was lower if the SPR was acquired in the anterior-posterior projection. The radiation dose with the posterior-anterior SPR was higher, because the divergence of the X-ray beam magnifies the anatomical structures closest to the tube, especially the spinal column, and this leads the ATCM system to estimate higher patient attenuation values and, therefore, to select higher tube current values. The NI was inversely proportional to the square root of the CTDI vol and, with fixed NI, the CTDI vol increased as the slice thickness decreased. This study suggests some important issues to use the GE ATCM system efficiently. (authors)

Development of plasma current waveform adjusting system ZLJ for tokamak device HL-1

International Nuclear Information System (INIS)

Wang Shangbing; Hu Haotian; Tang Fangqun; Zhou Yongzheng; Chu Xiuzhong; Cheng Jiashun; Gao Yunxia

1989-12-01

The control of some typical Tokamak discharge waveforms has been achieved by using plasma current waveform adjusting system ZLJ in the ohmic heating of HL-1. The discharge waveforms include a series of regular plasma current waveforms with various slow rising rate, such as 80 kA, 450 ms long flat-topping; 100 kA, 200 ms rising; 200 ms falt-topping and 180 kA, 400 ms slow rising etc. The design principle of the system and the initial experimental results are described

An evaluation of current EIA system in Pakistan

International Nuclear Information System (INIS)

Shah, I.A.; Romano, R.R.

2004-01-01

The challenge of reducing poverty and increasing economic growth has often led Pakistan to overlook environmental sustainability. Consequently, Pakistan, is suffering from severe environmental problems. This has spurred an increasing demand for and effective Environmental Impact Assessment (EIA) System with environmental management tools and techniques that can help the country to adequately diagnose their risks and suggest mitigation options. In the past few years Pakistan has begun implementing EIA' s as a preventive tool. However, given the judiciary, institutional and structural predicament, the outcome of the EIA process has resulted in great disparities. Given the growing regional environmental problems it is now a priority to seek an effective EIA systems, principles, and procedures in the country. This paper seeks to distinguish the Pakistan EIA strengths and weaknesses; it also focuses on identifying common positive and negative characteristics of the Pakistan EIA system. Furthermore, differences between the interested parties of the EIA system in the country were evaluated via a survey to ensure a good understanding of the factors of a comprehensive and effective EIA system. Analytical comparisons were made among the different interested parties of the EIA system in Pakistan. Statistical methods were used to analyze the data received and recommendations were made based on the outcome of the data results. These results will assist: (i) Pakistan to improve its EIA system (ii) other South Asian countries which may have a similar EIA systems in developing policy, planning and reforms and (iii) International organizations that work or invest in the region to enhance the attainment of environ- mental protection objectives on a broader, more cost effective, and realistic scale than current practices. (author)

Recent results with a high-current, heavy-ion source system

International Nuclear Information System (INIS)

Keller, R.; Spaedtke, P.; Emig, H.

1986-01-01

In the last conference of this series, an improved high-current ion source for gases, CORDIS was presented. This source has been further developed to allow the processing of substances which are not volatile at room temperature. One of these modifications, HORDIS, incorporates an oven whereas the third version works at rather moderate temperatures and can be fed through a slightly heated external bottle. With this source system, high-current ion beams in the 100 mA range can be produced for a considerable part of the periodic table. Operation parameters and experiences with the sources are discussed, and the most recent results for all versions are given. (author)

Lower hybrid heating and current drive in Iter operation scenarios and outline system design

International Nuclear Information System (INIS)

1994-11-01

Lower Hybrid Waves (LHW) are considered a valid method of plasma heating and the best demonstrated current drive method. Current drive by LHW possesses the unique feature, as compared to the other methods, to retain a good current drive efficiency in plasma regions of low to medium temperature, or in low-β phases of the discharges. This makes them an essential element to realize the so called 'advanced steady-state Tokamak scenarios' in which a hollow current density profile (deep shear reversal) - established during the ramp-up of the plasma current - offers the prospects of improved confinement and an MHD-stable route to continuous burn. This report contains both modelling and design studies of an LHW system for ITER. It aims primarily at the definition of concepts and parameters for steady-state operation using LHW combined with Fast Waves (FW), or other methods of generating a central seed current for high bootstrap current operation. However simulations addressing the use of LHW for current profile control in the high current pulsed operation scenario are also presented. The outline design of a LHW system which covers the needs for both pulsed and steady-state operation is described in detail. (author). 28 refs., 49 figs

Current Strategic Business Plan for the Implementation of Digital Systems.

Science.gov (United States)

Library of Congress, Washington, DC. National Library Service for the Blind and Physically Handicapped.

This document presents a current strategic business plan for the implementation of digital systems and services for the free national library program operated by the National Library Service for the Blind and Physically Handicapped, Library of Congress, its network of cooperating regional and local libraries, and the United States Postal Service.…

Research on Current Trends and Developments in Library Automation Systems.

Science.gov (United States)

Clyde, Laurel A.

A research project was undertaken in 1992 in order to identify, describe, and analyze current trends and developments in library automation systems and library software. The starting point is work conducted in 1988/1989 that formed the foundation of the book "Computer Software for School Libraries: A Directory." A 1992 survey of software…

Current transformer model with hysteresis for improving the protection response in electrical transmission systems

Science.gov (United States)

Matussek, Robert; Dzienis, Cezary; Blumschein, Jörg; Schulte, Horst

2014-12-01

In this paper, a generic enhanced protection current transformer (CT) model with saturation effects and transient behavior is presented. The model is used for the purpose of analysis and design of power system protection algorithms. Three major classes of protection CT have been modeled which all take into account the nonlinear inductance with remanence effects. The transient short-circuit currents in power systems are simulated under CT saturation condition. The response of a common power system protection algorithm with respect to robustness to nominal parameter variations and sensitivity against maloperation is demonstrated by simulation studies.

Current transformer model with hysteresis for improving the protection response in electrical transmission systems

International Nuclear Information System (INIS)

Matussek, Robert; Dzienis, Cezary; Blumschein, Jörg; Schulte, Horst

2014-01-01

In this paper, a generic enhanced protection current transformer (CT) model with saturation effects and transient behavior is presented. The model is used for the purpose of analysis and design of power system protection algorithms. Three major classes of protection CT have been modeled which all take into account the nonlinear inductance with remanence effects. The transient short-circuit currents in power systems are simulated under CT saturation condition. The response of a common power system protection algorithm with respect to robustness to nominal parameter variations and sensitivity against maloperation is demonstrated by simulation studies

Six types Monte Carlo for estimating the current unavailability of Markov system with dependent repair

International Nuclear Information System (INIS)

Xiao Gang; Li Zhizhong

2004-01-01

Based on integral equaiton describing the life-history of Markov system, six types of estimators of the current unavailability of Markov system with dependent repair are propounded. Combining with the biased sampling of state transition time of system, six types of Monte Carlo for estimating the current unavailability are given. Two numerical examples are given to deal with the variances and efficiencies of the six types of Monte Carlo methods. (authors)

Surface EEG-Transcranial Direct Current Stimulation (tDCS) Closed-Loop System.

Science.gov (United States)

Leite, Jorge; Morales-Quezada, Leon; Carvalho, Sandra; Thibaut, Aurore; Doruk, Deniz; Chen, Chiun-Fan; Schachter, Steven C; Rotenberg, Alexander; Fregni, Felipe

2017-09-01

Conventional transcranial direct current stimulation (tDCS) protocols rely on applying electrical current at a fixed intensity and duration without using surrogate markers to direct the interventions. This has led to some mixed results; especially because tDCS induced effects may vary depending on the ongoing level of brain activity. Therefore, the objective of this preliminary study was to assess the feasibility of an EEG-triggered tDCS system based on EEG online analysis of its frequency bands. Six healthy volunteers were randomized to participate in a double-blind sham-controlled crossover design to receive a single session of 10[Formula: see text]min 2[Formula: see text]mA cathodal and sham tDCS. tDCS trigger controller was based upon an algorithm designed to detect an increase in the relative beta power of more than 200%, accompanied by a decrease of 50% or more in the relative alpha power, based on baseline EEG recordings. EEG-tDCS closed-loop-system was able to detect the predefined EEG magnitude deviation and successfully triggered the stimulation in all participants. This preliminary study represents a proof-of-concept for the development of an EEG-tDCS closed-loop system in humans. We discuss and review here different methods of closed loop system that can be considered and potential clinical applications of such system.

Leakage Current Elimination of Four-Leg Inverter for Transformerless Three-Phase PV Systems

DEFF Research Database (Denmark)

Guo, Xiaoqiang; He, Ran; Jian, Jiamin

2016-01-01

Eliminating the leakage current is one of the most important issues for transformerless three phase photovoltaic (PV) systems. In this paper, the leakage current elimination of a three-phase four-leg PV inverter is investigated. With the common mode loop model established, the generation mechanism...... of the leakage current is clearly identified. Different typical carrier-based modulation methods and their corresponding common mode voltages are discussed. A new modulation strategy with Boolean logic function is proposed to achieve the constant common mode voltage for the leakage current reduction. Finally...

RMS Current of a Photovoltaic Generator in Grid-Connected PV Systems: Definition and Application

Directory of Open Access Journals (Sweden)

P. J. Pérez

2008-01-01

Full Text Available This paper includes a definition of a new and original concept in the photovoltaic field, RMS current of a photovoltaic generator for grid-connected systems. The RMS current is very useful for calculating energy losses in cables used in a PV generator. As well, a current factor has been defined in order to simplify RMS current calculation. This factor provides an immediate (quick and easy calculation method for the RMS current that does not depend on the case particular conditions (orientation, location, etc.. RMS current and current factor values have been calculated for different locations and modules.

The TS 600: automatic control system for eddy currents

International Nuclear Information System (INIS)

Poulet, J.P.

1986-10-01

In the scope of fabrication and in service inspection of the PWR steam generator tubing bendle, FRAMATOME developed an automatic Eddy Current testing system: TS600. Based on a mini-computer, TS600 allows to digitize, to store and to process data in various ways, so it is possible to perform several kinds of inspection: conventional inservice inspection, roll area profilometry...... TS600 can also be used to develop new methods of examination [fr

An optically coupled system for quantitative monitoring of MRI-induced RF currents into long conductors.

Science.gov (United States)

Zanchi, Marta G; Venook, Ross; Pauly, John M; Scott, Greig C

2010-01-01

The currents induced in long conductors such as guidewires by the radio-frequency (RF) field in magnetic resonance imaging (MRI) are responsible for potentially dangerous heating of surrounding media, such as tissue. This paper presents an optically coupled system with the potential to quantitatively measure the RF currents induced on these conductors. The system uses a self shielded toroid transducer and active circuitry to modulate a high speed light-emitting-diode transmitter. Plastic fiber guides the light to a photodiode receiver and transimpedance amplifier. System validation included a series of experiments with bare wires that compared wire tip heating by fluoroptic thermometers with the RF current sensor response. Validations were performed on a custom whole body 64 MHz birdcage test platform and on a 1.5 T MRI scanner. With this system, a variety of phenomena were demonstrated including cable trap current attenuation, lossy dielectric Q-spoiling and even transverse electromagnetic wave node patterns. This system should find applications in studies of MRI RF safety for interventional devices such as pacemaker leads, and guidewires. In particular, variations of this device could potentially act as a realtime safety monitor during MRI guided interventions.

An Optically-Coupled System for Quantitative Monitoring of MRI-Induced RF Currents into Long Conductors

Science.gov (United States)

Zanchi, Marta G.; Venook, Ross; Pauly, John M.; Scott, Greig C.

2010-01-01

The currents induced in long conductors such as guidewires by the radio frequency (RF) field in magnetic resonance imaging (MRI) are responsible for potentially dangerous heating of surrounding media, such as tissue. This paper presents an optically-coupled system with the potential to quantitatively measure the RF currents induced on these conductors. The system uses a self shielded toroid transducer and active circuitry to modulate a high speed LED transmitter. Plastic fiber guides the light to a photodiode receiver and transimpedance amplifier. System validation included a series of experiments with bare wires that compared wire tip heating by fluoroptic thermometers with the RF current sensor response. Validations were performed on a custom whole body 64 MHz birdcage test platform and on a 1.5T MRI scanner. With this system, a variety of phenomena were demonstrated including cable trap current attenuation, lossy dielectric Q-spoiling and even transverse electromagnetic wave node patterns. This system should find applications in studies of MRI RF safety for interventional devices such as pacemaker leads, and guidewires. In particular, variations of this device could potentially act as a realtime safety monitor during MRI guided interventions. PMID:19758855

Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems

KAUST Repository

Manchon, Aurelien

2018-01-29

Spin-orbit coupling in inversion-asymmetric magnetic crystals and structures has emerged as a powerful tool to generate complex magnetic textures, interconvert charge and spin under applied current, and control magnetization dynamics. Current-induced spin-orbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained magnetic oscillations or switching of ferromagnetic as well as antiferromagnetic structures. The manipulation of magnetic order, domain walls and skyrmions by spin-orbit torques provides evidence of the microscopic interactions between charge and spin in a variety of materials and opens novel strategies to design spintronic devices with potentially high impact in data storage, nonvolatile logic, and magnonic applications. This paper reviews recent progress in the field of spin-orbitronics, focusing on theoretical models, material properties, and experimental results obtained on bulk noncentrosymmetric conductors and multilayer heterostructures, including metals, semiconductors, and topological insulator systems. Relevant aspects for improving the understanding and optimizing the efficiency of nonequilibrium spin-orbit phenomena in future nanoscale devices are also discussed.

The MDSplus data acquisition system, current status and future directions

International Nuclear Information System (INIS)

Stillerman, J.; Fredian, T.W.

1999-01-01

The MDSplus data acquisition system was developed in collaboration with the ZTH group at Los Alamos National Laboratory and the RFX group at CNR in Padua, Italy and is currently in use at MIT, RFX in Padua, and TCV at EPFL in Lausanne. MDSplus is based on a hierarchical experiment description which completely describes the data acquisition and analysis tasks and contains the results from these operations. It also includes a set of X/motif based tools for data acquisition and display, as well as diagnostic configuration and management. These tools were designed to operate in a distributed, client/server environment with multiple concurrent readers and writers to the data store. An interface to a relational database is provided for storage and management of processed data. A commercially available package called IDL is used as the primary data analysis and visualization tool. The current projects include a new interface to the electronic logbook, tools for remote collaborators and WWW access, and a port of the system to UNIX and Windows-NT/95. (orig.)

Current-induced spin-orbit torques in ferromagnetic and antiferromagnetic systems

KAUST Repository

Manchon, Aurelien; Miron, I. M.; Jungwirth, T.; Sinova, J.; Zelezný , J.; Thiaville, A.; Garello, K.; Gambardella, P.

2018-01-01

Spin-orbit coupling in inversion-asymmetric magnetic crystals and structures has emerged as a powerful tool to generate complex magnetic textures, interconvert charge and spin under applied current, and control magnetization dynamics. Current-induced spin-orbit torques mediate the transfer of angular momentum from the lattice to the spin system, leading to sustained magnetic oscillations or switching of ferromagnetic as well as antiferromagnetic structures. The manipulation of magnetic order, domain walls and skyrmions by spin-orbit torques provides evidence of the microscopic interactions between charge and spin in a variety of materials and opens novel strategies to design spintronic devices with potentially high impact in data storage, nonvolatile logic, and magnonic applications. This paper reviews recent progress in the field of spin-orbitronics, focusing on theoretical models, material properties, and experimental results obtained on bulk noncentrosymmetric conductors and multilayer heterostructures, including metals, semiconductors, and topological insulator systems. Relevant aspects for improving the understanding and optimizing the efficiency of nonequilibrium spin-orbit phenomena in future nanoscale devices are also discussed.

High Accuracy Beam Current Monitor System for CEBAF'S Experimental Hall A

International Nuclear Information System (INIS)

J. Denard; A. Saha; G. Lavessiere

2001-01-01

CEBAF accelerator delivers continuous wave (CW) electron beams to three experimental Halls. In Hall A, all experiments require continuous, non-invasive current measurements and a few experiments require an absolute accuracy of 0.2 % in the current range from 1 to 180 (micro)A. A Parametric Current Transformer (PCT), manufactured by Bergoz, has an accurate and stable sensitivity of 4 (micro)A/V but its offset drifts at the muA level over time preclude its direct use for continuous measurements. Two cavity monitors are calibrated against the PCT with at least 50 (micro)A of beam current. The calibration procedure suppresses the error due to PCT's offset drifts by turning the beam on and off, which is invasive to the experiment. One of the goals of the system is to minimize the calibration time without compromising the measurement's accuracy. The linearity of the cavity monitors is a critical parameter for transferring the accurate calibration done at high currents over the whole dynamic range. The method for measuring accurately the linearity is described

Comparing Coral Reef Survey Methods. Unesco Reports in Marine Science No. 21 Report of a Regional Unesco/UNEP Workshop on Coral Reef Survey Management and Assessment Methods in Asia and the Pacific (Phuket, Thailand, December 13-17, 1982).

Science.gov (United States)

United Nations Educational, Scientific, and Cultural Organization, Paris (France). Div. of Marine Sciences.

This report includes nine papers prepared for a workshop on coral reef survey management and assessment methods in Asia and the Pacific. The papers are: "A Contrast in Methodologies between Surveying and Testing" (Charles Birkeland); "Coral Reef Survey Methods in the Andaman Sea" (Hansa Chansang); "A Review of Coral Reef…

Culture in Sustainability--Defining Cultural Sustainability in Education

Science.gov (United States)

Laine, Marja

2016-01-01

The definition of cultural sustainability in education is explored in this article by looking into conceptions of cultural sustainability collected through expert queries and focus group engagement. These conceptions are compared with the scientific and especially pedagogical discourse on the matter as well as Soini and Birkeland's theory of story…

A study on DC hybrid three-phase fault current limiting interrupter for a power distribution system

International Nuclear Information System (INIS)

Shao, Hongtian; Satoh, Tomoyuki; Yamaguchi, Mitsugi; Fukui, Satoshi; Ogawa, Jun; Satoh, Takao; Ishikawa, Hiroyuki

2005-01-01

For the purpose of protecting electric power system, many researches and developments of fault current limiters are being performed. The authors studied a dc hybrid three-phase fault current limiting interrupter (FCLI) composed of a superconducting reactor and an S/N transition element, connected in series each other. The dc hybrid type fault current limiting interrupter can limit a fault current by means of the inductance of high temperature superconducting (HTS) coil together with the normal transition of HTS bulk material (HTSB). In the case of an accident, the normal transition of the bulk material can be accelerated by the magnetic field of the HTS coil. In this paper, the dc hybrid type fault current limiting interrupter for 5.5 km long 6.6 kV-600 A power distribution system is analyzed, and performances of fault current limitation and interruption are confirmed. Moreover, a reclosing operation is discussed for this power distribution system

Mini Solar and Sea Current Power Generation System

Science.gov (United States)

Almenhali, Abdulrahman; Alshamsi, Hatem; Aljunaibi, Yaser; Almussabi, Dheyab; Alshehhi, Ahmed; Hilal, Hassan Bu

2017-07-01

The power demand in United Arab Emirates is increased so that there is a consistent power cut in our region. This is because of high power consumption by factories and also due to less availability of conventional energy resources. Electricity is most needed facility for the human being. All the conventional energy resources are depleting day by day. So we have to shift from conventional to non-conventional energy resources. In this the combination of two energy resources is takes place i.e. wind and solar energy. This process reviles the sustainable energy resources without damaging the nature. We can give uninterrupted power by using hybrid energy system. Basically this system involves the integration of two energy system that will give continuous power. Solar panels are used for converting solar energy and wind turbines are used for converting wind energy into electricity. This electrical power can utilize for various purpose. Generation of electricity will be takes place at affordable cost. This paper deals with the generation of electricity by using two sources combine which leads to generate electricity with affordable cost without damaging the nature balance. The purpose of this project was to design a portable and low cost power system that combines both sea current electric turbine and solar electric technologies. This system will be designed in efforts to develop a power solution for remote locations or use it as another source of green power.

Comments on Current Space Systems Observing the Climate

Science.gov (United States)

Fisk, L. A.

2016-07-01

The Global Climate Observing System (GCOS), which was established in 1992, has been effective in specifying the observations needed for climate studies, and advocating that these observations be made. As a result, there are essential climate variables being observed, particularly from space, and these have formed the basis for our ever-improving models of how the Earth system functions and the human impact on it. We cannot conclude, however, that the current observing system in space is adequate. Climate change is accelerating, and we need to ensure that our observations capture, with completeness and with proper resolution and cadence, the most important changes. Perhaps of most significance, we need to use observations from space to guide the mitigation and adaptation strategies on which at last our civilization seems prepared to embark. And we need to use our observations to educate particularly policy makers on the reality of climate change, so that none deny the need to act. COSPAR is determined to play its part in highlighting the need to strengthen the climate observing system and notably its research component. This is being accomplished through events like the present roundtable, through the work of its Scientific Commission A, its Task Group on GEO (where COSPAR is serving as a member of its Program Board), and by promoting among space agencies and policy-makers the recently released scientific roadmap on Integrated Earth System Science for the period 2016-2025.

Strengths and Weaknesses of the Current Dental Hygiene Educational System.

Science.gov (United States)

Theile, Cheryl Westphal

2017-09-01

The state of the dental hygiene educational system in the United States is evolving. The numbers of programs, extent of curricula, and diversity of students, faculty, and practice settings vary significantly across the country. New trends in workforce utilization and delivery models are challenging current educational foundations and mandating an interprofessional approach to both the education and practice of dental hygienists. This article presents an overview of the current state of dental hygiene education to create a baseline for discussion of desired educational models for 2040. The strengths and weaknesses are defined to motivate change. Limitations of the current two-year associate degree are emphasized, along with the need to add expanded content and development of new skills. The developing non-traditional practice settings bring both a challenge to dental hygiene education and a promise of increasing potential in primary care interprofessional settings for the 21 st century. This article was written as part of the project "Advancing Dental Education in the 21 st Century."

Nano-scale gene delivery systems; current technology, obstacles, and future directions.

Science.gov (United States)

Garcia-Guerra, Antonio; Dunwell, Thomas L; Trigueros, Sonia

2018-01-07

Within the different applications of nanomedicine currently being developed, nano-gene delivery is appearing as an exciting new technique with the possibility to overcome recognised hurdles and fulfill several biological and medical needs. The central component of all delivery systems is the requirement for the delivery of genetic material into cells, and for them to eventually reside in the nucleus where their desired function will be exposed. However, genetic material does not passively enter cells; thus, a delivery system is necessary. The emerging field of nano-gene delivery exploits the use of new materials and the properties that arise at the nanometre-scale to produce delivery vectors that can effectively deliver genetic material into a variety of different types of cells. The novel physicochemical properties of the new delivery vectors can be used to address the current challenges existing in nucleic acid delivery in vitro and in vivo. While there is a growing interest in nanostructure-based gene delivery, the field is still in its infancy, and there is yet much to discover about nanostructures and their physicochemical properties in a biological context. We carry out an organized and focused search of bibliographic databases. Our results suggest that despite new breakthroughs in nanostructure synthesis and advanced characterization techniques, we still face many barriers in producing highly efficient and non-toxic delivery systems. In this review, we overview the types of systems currently used for clinical and biomedical research applications along with their advantages and disadvantages, as well as discussing barriers that arise from nano-scale interactions with biological material. In conclusion, we hope that by bringing the far reaching multidisciplinary nature of nano-gene delivery to light, new targeted nanotechnology-bases strategies are developed to overcome the major challenges covered in this review. Copyright© Bentham Science Publishers; For

Proposal and Development of a High Voltage Variable Frequency Alternating Current Power System for Hybrid Electric Aircraft

Science.gov (United States)

Sadey, David J.; Taylor, Linda M.; Beach, Raymond F.

2017-01-01

The development of ultra-efficient commercial vehicles and the transition to low-carbon emission propulsion are seen as strategic thrust paths within NASA Aeronautics. A critical enabler to these paths comes in the form of hybrid electric propulsion systems. For megawatt-class systems, the best power system topology for these hybrid electric propulsion systems is debatable. Current proposals within NASA and the Aero community suggest using a combination of alternating current (AC) and direct current (DC) for power generation, transmission, and distribution. This paper proposes an alternative to the current thought model through the use of a primarily high voltage AC power system, supported by the Convergent Aeronautics Solutions (CAS) Project. This system relies heavily on the use of doubly-fed induction machines (DFIMs), which provide high power densities, minimal power conversion, and variable speed operation. The paper presents background on the activity along with the system architecture, development status, and preliminary results.

Real time control of EC heating & current drive systems on TCV

NARCIS (Netherlands)

Paley, J.I.; Felici, F.; Curchod, L.; Coda, S.; Goodman, T.P.

2009-01-01

The ability to control, in real time, the electron cyclotron heating & current drive systems for the control of MHD instabilities is particularly important for large tokamaks operating at high performance. Several algorithms have been developed and tested on TCV to explore possible control

Analysis of operations and cyber security policies for a system of cooperating Flexible Alternating Current Transmission System (FACTS) devices.

Energy Technology Data Exchange (ETDEWEB)

Phillips, Laurence R.; Tejani, Bankim; Margulies, Jonathan; Hills, Jason L.; Richardson, Bryan T.; Baca, Micheal J.; Weiland, Laura

2005-12-01

Flexible Alternating Current Transmission Systems (FACTS) devices are installed on electric power transmission lines to stabilize and regulate power flow. Power lines protected by FACTS devices can increase power flow and better respond to contingencies. The University of Missouri Rolla (UMR) is currently working on a multi-year project to examine the potential use of multiple FACTS devices distributed over a large power system region in a cooperative arrangement in which the FACTS devices work together to optimize and stabilize the regional power system. The report describes operational and security challenges that need to be addressed to employ FACTS devices in this way and recommends references, processes, technologies, and policies to address these challenges.

High-current heavy-ion accelerator system and its application to material modification

International Nuclear Information System (INIS)

Kishimoto, Naoki; Takeda, Yoshihiko; Lee, C.G.; Umeda, Naoki; Okubo, Nariaki; Iwamoto, Eiji

2001-01-01

A high-current heavy-ion accelerator system has been developed to realize intense particle fluxes for material modification. The facility of a tandem accelerator attained 1 mA-class ion current both for negative low-energy ions and positive high-energy ions. The negative ion source of the key device is of the plasma-sputter type, equipped with mutli-cusp magnets and Cs supply. The intense negative ions are either directly used for material irradiation at 60 keV or further accelerated up to 6 MeV after charge transformation. Application of negative ions, which alleviates surface charging, enables us to conduct low-energy high-current irradiation on insulating substrates. Since positive ions above the MeV range are irrelevant for Coulomb repulsion, the facility as a whole meets the needs of high-current irradiation onto insulators over a wide energy range. Application of high flux ions provides technological merits not only for efficient implantation but also for essentially different material kinetics, which may become an important tool of material modification. Other advantages of the system are co-irradiation by intense laser and in-situ detection of kinetic processes. For examples of material modifications, we present nanoparticle fabrication in insulators, and synergistic phenomena by co-irradiation due to ions and photons. (author)

DC current distribution mapping system of the solar panels using a HTS-SQUID gradiometer

International Nuclear Information System (INIS)

Miyazaki, Shingo; Kasuya, Syohei; Saari, Mohd Mawardi; Sakai, Kenji; Kiwa, Toshihiko; Tsukada, Keiji; Tsukamoto, Akira; Adachi, Seiji; Tanabe, Keiichi

2014-01-01

Solar panels are expected to play a major role as a source of sustainable energy. In order to evaluate solar panels, non-destructive tests, such as defect inspections and response property evaluations, are necessary. We developed a DC current distribution mapping system of the solar panels using a High Critical Temperature Superconductor Superconducting Quantum Interference Device (HTS-SQUID) gradiometer with ramp edge type Josephson junctions. Two independent components of the magnetic fields perpendicular to the panel surface (∂Bz/∂x, ∂Bz/∂y) were detected. The direct current of the solar panel is visualized by calculating the composition of the two signal components, the phase angle, and mapping the DC current vector. The developed system can evaluate the uniformity of DC current distributions precisely and may be applicable for defect detection of solar panels.

The Effects of Bursty Bulk Flows on Global-Scale Current Systems

Science.gov (United States)

Yu, Y.; Cao, J.; Fu, H.; Lu, H.; Yao, Z.

2017-12-01

Using a global magnetospheric MHD model coupled with a kinetic ring current model, we investigate the effects of magnetotail dynamics, particularly the earthward bursty bulk flows (BBFs) produced by the tail reconnection, on the global-scale current systems. The simulation results indicate that after BBFs brake around X = -10 RE due to the dipolar "magnetic wall," vortices are generated on the edge of the braking region and inside the inner magnetosphere. Each pair of vortex in the inner magnetosphere disturbs the westward ring current to arc radially inward as well as toward high latitudes. The resultant pressure gradient on the azimuthal direction induces region-1 sense field-aligned component from the ring current, which eventually is diverted into the ionosphere at high latitudes, giving rise to a pair of field-aligned current (FAC) eddies in the ionosphere. On the edge of the flow braking region where vortices also emerge, a pair of region-1 sense FACs arises, diverted fromthe cross-tail duskward current, generating a substorm current wedge. This is again attributed to the increase of thermal pressure ahead of the bursty flows turning azimuthally. It is further found that when multiple BBFs, despite their localization, continually and rapidly impinge on the "wall," carrying sufficient tail plasma sheet population toward the Earth, they can lead to the formation of a new ring current. These results indicate the important role that BBFs play in bridging the tail and the inner magnetosphere ring current and bring new insight into the storm-substorm relation.

Field-aligned current signatures in the near-tail region. 2. Coupling between the region 1 and region 2 systems

International Nuclear Information System (INIS)

Ohtani, S.; Kokubun, S.; Nakamura, R.; Elphic, R.C.; Russell, C.T.; Baker, D.N.

1990-01-01

The development of the substorm-associated current system in the near-tail region is examined in the light of both experiment and theory. First, the March 28, 1979, event is examined intensively by using ground magnetometer data and satellite magnetic field and energetic particle data. The comparison of field-aligned current signatures at geosynchronous altitude and in the near-tail region indicates that the development of the region 1 system is not merely the enhancement in current intensity of the pre-existing system. This finding is consistent with the so-called current wedge model, in which the tail current is converted into a pair of field-aligned currents with the region 1 polarity at substorm onsets. Detailed inspection, however, suggests that the region 2 system is as important as the region 1 system. Statistical properties of the azimuthal magnetic component at synchronous orbit indicate that the deviation during disturbed periods is larger than expected from the enhancement of the region 1 current. These individual and statistical studies suggest that the region 2 system tends to develop in the synchronous region and that the coupling between the region 1 and the region 2 systems is important. The current closure in the magnetosphere is discussed from a viewpoint of the macroscopic behavior of plasma. It is suggested that the dawnside and the duskside region 2 currents are closed in the magnetosphere by the curvature current during the growth phase and by the magnetic gradient current during the expansion phase. The field-aligned currents of the region 1 and the region 2 systems are closed in the ionosphere by the Pedersen current. Consequently, the energy is dissipated as the Joule heating and this energy must be supplied from the magnetosphere. Therefore, the counter part of the Pedersen current, which closes the region 1 and the region 2 currents in magnetosphere, must be the dynamo current

Predictability of the California Current System

Science.gov (United States)

Miller, Arthur J.; Chereskin, T.; Cornuelle, B. D.; Niiler, P. P.; Moisan, J. R.; Lindstrom, Eric (Technical Monitor)

2001-01-01

The physical and biological oceanography of the Southern California Bight (SCB), a highly productive subregion of the California Current System (CCS) that extends from Point Conception, California, south to Ensenada, Mexico, continues to be extensively studied. For example, the California Cooperative Oceanic Fisheries Investigations (CalCOFI) program has sampled this region for over 50 years, providing an unparalleled time series of physical and biological data. However, our understanding of what physical processes control the large-scale and mesoscale variations in these properties is incomplete. In particular, the non-synoptic and relatively coarse spatial sampling (70km) of the hydrographic grid does not completely resolve the mesoscale eddy field (Figure 1a). Moreover, these unresolved physical variations exert a dominant influence on the evolution of the ecosystem. In recent years, additional datasets that partially sample the SCB have become available. Acoustic Doppler Current Profiler (ADCP) measurements, which now sample upper-ocean velocity between stations, and sea level observations along TOPEX tracks give a more complete picture of the mesoscale variability. However, both TOPEX and ADCP are well-sampled only along the cruise or orbit tracks and coarsely sampled in time and between tracks. Surface Lagrangian drifters also sample the region, although irregularly in time and space. SeaWiFS provides estimates of upper-ocean chlorophyll-a (chl-alpha), usually giving nearly complete coverage for week-long intervals, depending on cloud coverage. Historical ocean color data from the Coastal Zone Color Scanner (CZCS) has been used extensively to determine phytoplankton patterns and variability, characterize the primary production across the SCB coastal fronts, and describe the seasonal and interannual variability in pigment concentrations. As in CalCOFI, these studies described much of the observed structures and their variability over relatively large space and

Eddy current testing system for bottom mounted instrumentation welds

OpenAIRE

Kobayashi Noriyasu; Ueno Souichi; Suganuma Naotaka; Oodake Tatsuya; Maehara Takeshi; Kasuya Takashi; Ichikawa Hiroya

2015-01-01

The capability of eddy current testing (ECT) for the bottom mounted instrumentation (BMI) weld area of reactor vessel in a pressurized water reactor was demonstrated by the developed ECT system and procedure. It is difficult to position and move the probe on the BMI weld area because the area has complexly curved surfaces. The space coordinates and the normal vectors at the scanning points were calculated as the scanning trajectory of probe based on the measured results of surface shape on th...

Current status of quality assurance of treatment planning systems

International Nuclear Information System (INIS)

Mijnheer, B.J.

1997-01-01

A review is given of the current status of quality assurance of treatment planning systems. At this moment only one comprehensive report is available. In order to review national activities a questionnaire has been distributed amongst national societies of medical physicists. From the 23 responding countries, 8 indicated that only limited efforts are underway, 8 answered that a working group is evaluating their specific national requirements while in 5 countries a document is drafted. The highlights of these reports have been summarized. (author)

Voltage-current characteristics of a pin-plate system with different plate configurations

International Nuclear Information System (INIS)

Feng, Zhuangbo; Long, Zhengwei

2013-01-01

In this paper, the voltage-current (V-I) characteristics of a pin-plate system with four types of collection plate configurations are studied experimentally. The collection plates consider a single metal plate, a metal plate with a fly ash cake layer, a metal plate with a clean filter media and a metal plate with a dirty filter media. The results show that the clean filter media has no obvious effect on the V-I characteristics. But the dirty filter media reduces the current density because of its high resistance. The thick fly ash cake layer increase current density because of the anti-corona effect but the increment is not very obvious.

Design Considerations for CMOS Current Mode Operational Amplifiers and Current Conveyors

DEFF Research Database (Denmark)

Bruun, Erik

implementations of current mode opamps in CMOS technology are described. Also, current conveyor configurations with multiple outputs and flexible feedback connections from outputs to inputs are introduced. The dissertation includes several examples of circuit configurations ranging from simple class A and class......This dissertation is about CMOS current conveyors and current mode operational amplifiers (opamps). They are generic devices for continuous time signal processing in circuits and systems where signals are represented by currents.Substantial advancements are reported in the dissertation, both...... related to circuit implementations and system configurations and to an analysis of the fundamental limitations of the current mode technique.In the field of system configurations and circuit implementations different configurations of high gain current opamps are introduced and some of the first...

Beam-driven currents in the 1/ν regime in a helical system

International Nuclear Information System (INIS)

Nakajima, Noriyoshi; Okamoto, Masao.

1990-04-01

Beam currents driven by a neutral particle injection in a helical system (stellarator, heliotron/torsatron) are studied in the 1/ν collisionality regime. The general expression for the beam-driven current is obtained for arbitrary magnetic field configurations by solving the drift kinetic equation for electrons. It is found that F = J(net)/J(b) (J(net) is the net current and J(b) is the fast ion beam current) increases as f(t) and Zeff where f(t) is the fraction of trapped electrons and Zeff is the effective ionic charge number. Especially, for Zeff ≅ 1 the effect of trapped electrons is large and F is roughly proportional to f(t). On the other hand, if Zeff > or approx 3 the effect of trapped electrons becomes small. (author)

Spin force and the generation of sustained spin current in time-dependent Rashba and Dresselhaus systems

International Nuclear Information System (INIS)

Ho, Cong Son; Tan, Seng Ghee; Jalil, Mansoor B. A.

2014-01-01

The generation of spin current and spin polarization in a two-dimensional electron gas structure is studied in the presence of Dresselhaus and Rashba spin-orbit couplings (SOC), the strength of the latter being modulated in time by an ac gate voltage. By means of the non-Abelian gauge field approach, we established the relation between the Lorentz spin force and the spin current in the SOC system, and showed that the longitudinal component of the spin force induces a transverse spin current. For a constant (time-invariant) Rashba system, we recover the universal spin Hall conductivity of e/(8π) , derived previously via the Berry phase and semi-classical methods. In the case of a time-dependent SOC system, the spin current is sustained even under strong impurity scattering. We evaluated the ac spin current generated by a time-modulated Rashba SOC in the absence of any dc electric field. The magnitude of the spin current reaches a maximum when the modulation frequency matches the Larmor frequency of the electrons

A current controlled matrix converter for wind energy conversion systems based on permanent magnet synchronous generator

OpenAIRE

Naggar H. Saad; Ahmed A. El-Sattar; Mohamed I. Marei

2016-01-01

The main challenges of wind energy conversion systems (WECS) are to maximize the energy capture from the wind and injecting reactive power during the fault. This paper presents a current controlled matrix converter to interface Permanent Magnet Synchronous Generators (PMSG) based WECS with the grid. To achieve fast dynamic response with reduced current ripples, a hysteresis current control is utilized. The proposed control system decouples the active and reactive components of the PMSG curren...

Middle atmosphere electrical energy coupling

Science.gov (United States)

Hale, L. C.

1989-01-01

The middle atmosphere (MA) has long been known as an absorber of radio waves, and as a region of nonlinear interactions among waves. The region of highest transverse conductivity near the top of the MA provides a common return for global thunderstorm, auroral Birkeland, and ionospheric dynamo currents, with possibilities for coupling among them. Their associated fields and other transverse fields map to lower altitudes depending on scale size. Evidence now exists for motion-driven aerosol generators, and for charge trapped at the base of magnetic field lines, both capable of producing large MA electric fields. Ionospheric Maxwell currents (curl H) parallel to the magnetic field appear to map to lower altitudes, with rapidly time-varying components appearing as displacement currents in the stratosphere. Lightning couples a (primarily ELF and ULF) current transient to the ionosphere and magnetosphere whose wave shape is largely dependent on the MA conductivity profile. Electrical energy is of direct significance mainly in the upper MA, but electrodynamic transport of minor constituents such as smoke particles or CN may be important at other altitudes.

A fast high-voltage current-peak detection system for the ALICE transition radiation detector

Energy Technology Data Exchange (ETDEWEB)

Verclas, Robert [Physikalisches Institut, Ruprecht-Karls-Universitaet Heidelberg (Germany); Collaboration: ALICE-Collaboration

2016-07-01

During LHC operation in run 1, the gaseous detectors of ALICE occasionally experienced simultaneous trips in their high voltage which affected the majority of the high voltage channels. These trips are caused by large anode currents in the detector and are potentially related to LHC machine operations. We developed and installed a fast current-peak detection system for the ALICE Transition Radiation Detector. This system is based on FPGA technology and monitors 144 out 522 high voltage channels minimally invasively at a maximum readout rate of 2 MHz. It is an integral part of the LHC beam monitoring system. We report on the latest status.

Design of an end station for a high current ion implantation system

International Nuclear Information System (INIS)

Kranik, J.R.

1979-01-01

During the last 4 to 5 years IBM has been involved in an effort to develop a high current Ion Implantation system with pre-deposition capabilities. The system is dedicated to Arsenic implants, involving doses > 1 x 10 15 ions/cm 2 in the energy range of 30 to 60 keV. A major portion of this effort involved the design of an associated end station capable of producing high uniformity implants with beam currents in the 0.5 to 6.0 mA range. The end station contains all components from the exit of the analyzing magnet, including the exit beamline, process chamber, scan system, wafer handling system, high vacuum pumping package, beam optics, dosimetry system, and associated electronic controls. The unit was restricted to a six wafer (82 mm) batch size to maintain process line compatibility. In addition, implant dose non-uniformity objectives were established at +- 3% (2σ) within a wafer and +- 2% (2σ) wafer-to-wafer. Also, the system was to be capable of implanting 24 wafers/hour at a dose of 7.5 x 10 15 ions/cm 2 . Major consideration in the design was afforded to high reliability, ease of maintenance and production level throughput capabilities. The rationale and evolution of the final end station design is described. (author)

Food reward system: current perspectives and future research needs.

Science.gov (United States)

Alonso-Alonso, Miguel; Woods, Stephen C; Pelchat, Marcia; Grigson, Patricia Sue; Stice, Eric; Farooqi, Sadaf; Khoo, Chor San; Mattes, Richard D; Beauchamp, Gary K

2015-05-01

This article reviews current research and cross-disciplinary perspectives on the neuroscience of food reward in animals and humans, examines the scientific hypothesis of food addiction, discusses methodological and terminology challenges, and identifies knowledge gaps and future research needs. Topics addressed herein include the role of reward and hedonic aspects in the regulation of food intake, neuroanatomy and neurobiology of the reward system in animals and humans, responsivity of the brain reward system to palatable foods and drugs, translation of craving versus addiction, and cognitive control of food reward. The content is based on a workshop held in 2013 by the North American Branch of the International Life Sciences Institute. © The Author(s) 2015. Published by Oxford University Press on behalf of the International Life Sciences Institute.

Nonequilibrium Distribution of the Microscopic Thermal Current in Steady Thermal Transport Systems

KAUST Repository

Yukawa, Satoshi; Ogushi, Fumiko; Shimada, Takashi; Ito, Nobuyasu

2010-01-01

Nonequilibrium distribution of the microscopic thermal current is investigated by direct molecular dynamics simulations. The microscopic thermal current in this study is defined by a flow of kinetic energy carried by a single particle. Asymptotic parallel and antiparallel tails of the nonequilibrium distribution to an average thermal current are identical to ones of equilibrium distribution with different temperatures. These temperatures characterizing the tails are dependent on a characteristic length in which a memory of dynamics is completely erased by several particle collisions. This property of the tails of nonequilibrium distribution is confirmed in other thermal transport systems. In addition, statistical properties of a particle trapped by a harmonic potential in a steady thermal conducting state are also studied. This particle feels a finite force parallel to the average thermal current as a consequence of the skewness of the distribution of the current. This force is interpreted as the microscopic origin of thermophoresis.

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.

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

International Nuclear Information System (INIS)

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

2014-01-01

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

Power Management Based Current Control Technique for Photovoltaic-Battery Assisted Wind-Hydro Hybrid System

Science.gov (United States)

Ram Prabhakar, J.; Ragavan, K.

2013-07-01

This article proposes new power management based current control strategy for integrated wind-solar-hydro system equipped with battery storage mechanism. In this control technique, an indirect estimation of load current is done, through energy balance model, DC-link voltage control and droop control. This system features simpler energy management strategy and necessitates few power electronic converters, thereby minimizing the cost of the system. The generation-demand (G-D) management diagram is formulated based on the stochastic weather conditions and demand, which would likely moderate the gap between both. The features of management strategy deploying energy balance model include (1) regulating DC-link voltage within specified tolerances, (2) isolated operation without relying on external electric power transmission network, (3) indirect current control of hydro turbine driven induction generator and (4) seamless transition between grid-connected and off-grid operation modes. Furthermore, structuring of the hybrid system with appropriate selection of control variables enables power sharing among each energy conversion systems and battery storage mechanism. By addressing these intricacies, it is viable to regulate the frequency and voltage of the remote network at load end. The performance of the proposed composite scheme is demonstrated through time-domain simulation in MATLAB/Simulink environment.

Progress in the ITER electron cyclotron heating and current drive system design

Energy Technology Data Exchange (ETDEWEB)

Omori, Toshimichi, E-mail: toshimichi.omori@iter.org [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Albajar, Ferran; Bonicelli, Tullio; Carannante, Giuseppe; Cavinato, Mario; Cismondi, Fabio [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Darbos, Caroline [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Denisov, Grigory [Institute of Applied Physics Russian Academy of Sciences, 46 Ulyanov Street, Nizhny Novgorod 603950 (Russian Federation); Farina, Daniela [Istituto di Fisica del Plasma, Association EURATOM-ENEA-CNR, Milano (Italy); Gagliardi, Mario [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Gandini, Franco; Gassmann, Thibault [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Goodman, Timothy [CRPP, Association EURATOM-Confédération Suisse, EPFL Ecublens, CH-1015 Lausanne (Switzerland); Hanson, Gregory [US ITER Project Office, ORNL, 055 Commerce Park, PO Box 2008, Oak Ridge, TN 37831 (United States); Henderson, Mark A. [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St Paul Lez Durance Cedex (France); Kajiwara, Ken [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka-shi, Ibaraki 311-0193 (Japan); McElhaney, Karen [US ITER Project Office, ORNL, 055 Commerce Park, PO Box 2008, Oak Ridge, TN 37831 (United States); Nousiainen, Risto [Fusion for Energy, Josep Pla 2, Barcelona 08019 (Spain); Oda, Yasuhisa [Japan Atomic Energy Agency (JAEA), 801-1 Mukoyama, Naka-shi, Ibaraki 311-0193 (Japan); Oustinov, Alexander [Institute of Applied Physics Russian Academy of Sciences, 46 Ulyanov Street, Nizhny Novgorod 603950 (Russian Federation); and others

2015-10-15

Highlights: • EC system is designed with an ability to upgrade in power to 28 MW then 40 MW. • The TL is capable of 3 buildings movements; ±15 mm displacements at the worst. • Improved power deposition access injecting 20 MW across nearly the entire plasma. • Ensured nuclear safety by appropriate definition of confinement boundaries. • Proposed I&C architecture for the overall EC plant was successfully reviewed. - Abstract: An electron cyclotron system is one of the four auxiliary plasma heating systems to be installed on the ITER tokamak. The ITER EC system consists of 24 gyrotrons with associated 12 high voltage power supplies, a set of evacuated transmission lines and two types of launchers. The whole system is designed to inject 20 MW of microwave power at 170 GHz into the plasma. The primary functions of the system include plasma start-up, central heating and current drive, and magneto-hydrodynamic instabilities control. The design takes present day technology and extends towards high power CW operation, which represents a large step forward as compared to the present state of the art. The ITER EC system will be a stepping stone to future EC systems for DEMO and beyond. The EC system is faced with significant challenges, which not only includes an advanced microwave system for plasma heating and current drive applications but also has to comply with stringent requirements associated with nuclear safety as ITER became the first fusion device licensed as basic nuclear installations as of 9 November 2012. Since conceptual design of the EC system established in 2007, the EC system has progressed to a preliminary design stage in 2012, and is now moving forward towards a final design. The majority of the subsystems have completed the detailed design and now advancing towards the final design completion.

Progress in the ITER electron cyclotron heating and current drive system design

International Nuclear Information System (INIS)

Omori, Toshimichi; Albajar, Ferran; Bonicelli, Tullio; Carannante, Giuseppe; Cavinato, Mario; Cismondi, Fabio; Darbos, Caroline; Denisov, Grigory; Farina, Daniela; Gagliardi, Mario; Gandini, Franco; Gassmann, Thibault; Goodman, Timothy; Hanson, Gregory; Henderson, Mark A.; Kajiwara, Ken; McElhaney, Karen; Nousiainen, Risto; Oda, Yasuhisa; Oustinov, Alexander

2015-01-01

Highlights: • EC system is designed with an ability to upgrade in power to 28 MW then 40 MW. • The TL is capable of 3 buildings movements; ±15 mm displacements at the worst. • Improved power deposition access injecting 20 MW across nearly the entire plasma. • Ensured nuclear safety by appropriate definition of confinement boundaries. • Proposed I&C architecture for the overall EC plant was successfully reviewed. - Abstract: An electron cyclotron system is one of the four auxiliary plasma heating systems to be installed on the ITER tokamak. The ITER EC system consists of 24 gyrotrons with associated 12 high voltage power supplies, a set of evacuated transmission lines and two types of launchers. The whole system is designed to inject 20 MW of microwave power at 170 GHz into the plasma. The primary functions of the system include plasma start-up, central heating and current drive, and magneto-hydrodynamic instabilities control. The design takes present day technology and extends towards high power CW operation, which represents a large step forward as compared to the present state of the art. The ITER EC system will be a stepping stone to future EC systems for DEMO and beyond. The EC system is faced with significant challenges, which not only includes an advanced microwave system for plasma heating and current drive applications but also has to comply with stringent requirements associated with nuclear safety as ITER became the first fusion device licensed as basic nuclear installations as of 9 November 2012. Since conceptual design of the EC system established in 2007, the EC system has progressed to a preliminary design stage in 2012, and is now moving forward towards a final design. The majority of the subsystems have completed the detailed design and now advancing towards the final design completion.

The dispersion relation of charge and current compensated relativistic electron beam-plasma system

International Nuclear Information System (INIS)

Vrba, P.; Schroetter, J.; Jarosova, P.; Koerbel, S.

1978-01-01

The unstable regions of relativistic electron beam-plasma system were determined by analysing the general dispersion relation numerically. The external parameters were varied to ensure more effective instability excitations. The full charge- and current compensation presumptions lead to the new synchronism predictions. The slow space charge wave and slow cyclotron wave of the return current are synchronous with the plasma ion wave. (author)

Study of Security Attributes of Smart Grid Systems- Current Cyber Security Issues

Energy Technology Data Exchange (ETDEWEB)

Wayne F. Boyer; Scott A. McBride

2009-04-01

This document provides information for a report to congress on Smart Grid security as required by Section 1309 of Title XIII of the Energy Independence and Security Act of 2007. The security of any future Smart Grid is dependent on successfully addressing the cyber security issues associated with the nation’s current power grid. Smart Grid will utilize numerous legacy systems and technologies that are currently installed. Therefore, known vulnerabilities in these legacy systems must be remediated and associated risks mitigated in order to increase the security and success of the Smart Grid. The implementation of Smart Grid will include the deployment of many new technologies and multiple communication infrastructures. This report describes the main technologies that support Smart Grid and summarizes the status of implementation into the existing U.S. electrical infrastructure.

Implications of ITER requirements on R and D of RF heating and current drive systems

International Nuclear Information System (INIS)

Bosia, G.; Agarici, G.; Beaumont, B.

2003-01-01

Heating and Current Drive (H and CD) systems have an essential role in ITER-FEAT operation, as all phases of ITER operation are driven and controlled by the auxiliary power flow. The RF (Electron Cyclotron and Ion Cyclotron) systems, planned to contribute for ∼ 60% of the total auxiliary power (72 MW), with Lower Hybrid used for the specialised function of current drive in the extended performance phase (20 MW), are at different level of technology development. All systems, need a significant development in order to meet ITER operation requirements In this paper these requirements are reviewed and CEA proposals for the development of the Ion cyclotron system presented. (author)

An Ionosphere/Magnetosphere Coupling Current System Located in the Gap Between Saturn and its Rings

Science.gov (United States)

Khurana, K. K.; Dougherty, M. K.; Cao, H.; Hunt, G. J.; Provan, G.

2017-12-01

The Grand Finale Orbits of the Cassini spacecraft traversed through Saturn's D ring and brought the spacecraft to within 3000 km of Saturn's cloud tops. The closest approaches (CA) were near the equatorial plane of Saturn and were distributed narrowly around the local noon. The difference field (observations - internal field - magnetospheric ring current field) obtained from the Grand Finale orbits show persistent residual fields centered around the CA which diminish at higher latitudes on field lines that connect to the ring. Modeling of this perturbation in terms of internal harmonics shows that the perturbation is not of internal origin but is produced by external currents that couple the ionosphere to the magnetosphere. The sense of the current system suggests that the southern feet of the field lines in the ionosphere lead their northern footprints. We show that the observed field perturbations are consistent with a meridional Pedersen current whose strength is 1 MA/radian, i.e. comparable in strength to the Planetary-period-oscillation related current systems observed in the auroral zone. We show that the implied Lorentz force in the ionosphere extracts momentum from the faster moving southern ionosphere and passes it on to the northern ionosphere. We discuss several ideas for generating this current system. In particular, we highlight a mechanism that involves shears in the neutral winds in the thermospheric region to generate the observed magnetic field.

The current system of higher education in India inherits the legacy

Indian Academy of Sciences (India)

The current system of higher education in India inherits the legacy of colonial proposals and legislations dating back to the early 19th century. The social sciences and humanities still carry disciplinary burdens that need revisiting as we attempt to think of new educational strategies for the 21st century.

Measurement-based harmonic current modeling of mobile storage for power quality study in the distribution system

Directory of Open Access Journals (Sweden)

Wenge Christoph

2017-12-01

Full Text Available Electric vehicles (EVs can be utilized as mobile storages in a power system. The use of battery chargers can cause current harmonics in the supplied AC system. In order to analyze the impact of different EVs with regardto their number and their emission of current harmonics, a generic harmonic current model of EV types was built and implemented in the power system simulation tool PSS®NETOMAC. Based on the measurement data for different types of EVs three standardized harmonic EV models were developed and parametrized. Further, the identified harmonic models are used by the computation of load flow in a modeled, German power distribution system. As a benchmark, a case scenario was studied regarding a high market penetration of EVs in the year 2030 for Germany. The impact of the EV charging on the power distribution system was analyzed and evaluated with valid power quality standards.

An "Off-the-Shelf" System for Intraprocedural Electrical Current Evaluation and Monitoring of Irreversible Electroporation Therapy.

Science.gov (United States)

Neal, Robert E; Kavnoudias, Helen; Thomson, Kenneth R

2015-06-01

Irreversible electroporation (IRE) ablation uses a series of brief electric pulses to create nanoscale defects in cell membranes, killing the cells. It has shown promise in numerous soft-tissue tumor applications. Larger voltages between electrodes will increase ablation volume, but exceeding electrical limits may risk damage to the patient, cause ineffective therapy delivery, or require generator restart. Monitoring electrical current for these conditions in real-time enables managing these risks. This capacity is not presently available in clinical IRE generators. We describe a system using a Tektronix TCP305 AC/DC Current Probe connected to a TCPA300 AC/DC Current Probe Amplifier, which is read on a computer using a Protek DSO-2090 USB computer-interfacing oscilloscope. Accuracy of the system was tested with a resistor circuit and by comparing measured currents with final outputs from the NanoKnife clinical electroporation pulse generator. Accuracy of measured currents was 1.64 ± 2.4 % relative to calculations for the resistor circuit and averaged 0.371 ± 0.977 % deviation from the NanoKnife. During clinical pulse delivery, the system offers real-time evaluation of IRE procedure progress and enables a number of methods for identifying approaching issues from electrical behavior of therapy delivery, facilitating protocol changes before encountering therapy delivery issues. This system can monitor electrical currents in real-time without altering the electric pulses or modifying the pulse generator. This facilitates delivering electric pulse protocols that remain within the optimal range of electrical currents-sufficient strength for clinically relevant ablation volumes, without the risk of exceeding safe electric currents or causing inadequate ablation.

Studies of Polar Current Systems Using the IMS Scandinavian Magnetometer Array

Science.gov (United States)

Untiedt, J.; Baumjohann, W.

1993-09-01

As a contribution to the International Magnetospheric Study (IMS, 1976 1979) a two-dimensional array of 42 temporary magnetometer stations was run in Scandinavia, supplementary to the permanent observatories and concentrated in the northern part of the region. This effort aimed at the time-dependent (periods above about 100 s) determination of the two-dimensional structure of substorm-related magnetic fields at the Earth's surface with highest reasonable spatial resolution (about 100 km, corresponding to the height of the ionosphere) near the footpoints of field-aligned electric currents that couple the disturbed magnetosphere to the ionosphere at auroral latitudes. It has been of particular advantage for cooperative studies that not only simultaneous data were available from all-sky cameras, riometers, balloons, rockets, and satellites, but also from the STARE radar facility yielding colocated two-dimensional ionospheric electric field distributions. In many cases it therefore was possible to infer the three-dimensional regional structure of substorm-related ionospheric current systems. The first part of this review outlines the basic relationships and methods that have been used or have been developed for such studies. The second short part presents typical equivalent current patterns observed by the magnetometer array in the course of substorms. Finally we review main results of studies that have been based on the magnetometer array observations and on additional data, omitting studies on geomagnetic pulsations. These studies contributed to a clarification of the nature of auroral electrojets including the Harang discontinuity and of ionospheric current systems related to auroral features such as the break-up at midnight, the westward traveling surge, eastward drifting omega bands, and spirals.

Adjustable direct current and pulsed circuit fault current limiter

Science.gov (United States)

Boenig, Heinrich J.; Schillig, Josef B.

2003-09-23

A fault current limiting system for direct current circuits and for pulsed power circuit. In the circuits, a current source biases a diode that is in series with the circuits' transmission line. If fault current in a circuit exceeds current from the current source biasing the diode open, the diode will cease conducting and route the fault current through the current source and an inductor. This limits the rate of rise and the peak value of the fault current.

Remarks on time-dependent [current]-density functional theory for open quantum systems.

Science.gov (United States)

Yuen-Zhou, Joel; Aspuru-Guzik, Alán

2013-08-14

Time-dependent [current]-density functional theory for open quantum systems (OQS) has emerged as a formalism that can incorporate dissipative effects in the dynamics of many-body quantum systems. Here, we review and clarify some formal aspects of these theories that have been recently questioned in the literature. In particular, we provide theoretical support for the following conclusions: (1) contrary to what we and others had stated before, within the master equation framework, there is in fact a one-to-one mapping between vector potentials and current densities for fixed initial state, particle-particle interaction, and memory kernel; (2) regardless of the first conclusion, all of our recently suggested Kohn-Sham (KS) schemes to reproduce the current and particle densities of the original OQS, and in particular, the use of a KS closed driven system, remains formally valid; (3) the Lindblad master equation maintains the positivity of the density matrix regardless of the time-dependence of the Hamiltonian or the dissipation operators; (4) within the stochastic Schrödinger equation picture, a one-to-one mapping from stochastic vector potential to stochastic current density for individual trajectories has not been proven so far, except in the case where the vector potential is the same for every member of the ensemble, in which case, it reduces to the Lindblad master equation picture; (5) master equations may violate certain desired properties of the density matrix, such as positivity, but they remain as one of the most useful constructs to study OQS when the environment is not easily incorporated explicitly in the calculation. The conclusions support our previous work as formally rigorous, offer new insights into it, and provide a common ground to discuss related theories.

Development of RF-linac and storage ring system for high-current experiments at GSI

International Nuclear Information System (INIS)

Hofmann, I.

1986-08-01

The heavy ion facility under construction at GSI is suitable for the generation of high-current beams. It consists of a new high-current injector into the Unilac and a synchrotron and storage ring. We discuss the capability of this system to produce short pulses of heavy ions with a specific energy of the order of 0.1 MJ/g. Under these conditions the system allows to perform a first generation of heavy ion driven target experiments and to test most of the critical issues of a large scale heavy ion fusion driver facility. (orig.)

Eddy current system for inspection of train hollow axles

Energy Technology Data Exchange (ETDEWEB)

Chady, Tomasz; Psuj, Grzegorz; Sikora, Ryszard; Kowalczyk, Jacek; Spychalski, Ireneusz [Department of Electrical and Computer Engineering, Faculty of Electrical Engineering, West Pomeranian University of Technology, Szczecin (Poland)

2014-02-18

The structural integrity of wheelsets used in rolling stock is of great importance to the safety. In this paper, electromagnetic system with an eddy current transducer suitable for the inspection of hollow axles have been presented. The transducer was developed to detect surface braking defects having depth not smaller than 0.5 mm. Ultrasound technique can be utilized to inspect the whole axle, but it is not sufficiently sensitive to shallow defects located close to the surface. Therefore, the electromagnetic technique is proposed to detect surface breaking cracks that cannot be detected by ultrasonic technique.

Advanced antenna system for Alfven wave plasma heating and current drive in TCABR tokamak

International Nuclear Information System (INIS)

Ruchko, L.F.; Ozono, E.; Galvao, R.M.O.; Nascimento, I.C.; Degasperi, F.T.; Lerche, E.

1998-01-01

An advanced antenna system that has been developed for investigation of Alfven wave plasma heating and current drive in the TCABR tokamak is described. The main goal was the development of such a system that could insure the excitation of travelling single helicity modes with predefined wave mode numbers M and N. The system consists of four similar modules with poloidal windings. The required spatial spectrum is formed by proper phasing of the RF feeding currents. The impedance matching of the antenna with the four-phase oscillator is accomplished by resonant circuits which form one assembly unit with the RF feeders. The characteristics of the antenna system design with respect to the antenna-plasma coupling and plasma wave excitation, for different phasing of the feeding currents, are summarised. The antenna complex impedance Z=Z R +Z I is calculated taking into account both the plasma response to resonant excitation of fast Alfven waves and the nonresonant excitation of vacuum magnetic fields in conducting shell. The matching of the RF generator with the antenna system during plasma heating is simulated numerically, modelling the plasma response with mutually coupled effective inductances with corresponding active Z R and reactive Z I impedances. The results of the numerical simulation of the RF system performance, including both the RF magnetic field spectrum analysis and the modeling of the RF generator operation with plasma load, are presented. (orig.)

Validation Test Results for Orthogonal Probe Eddy Current Thruster Inspection System

Science.gov (United States)

Wincheski, Russell A.

2007-01-01

Recent nondestructive evaluation efforts within NASA have focused on an inspection system for the detection of intergranular cracking originating in the relief radius of Primary Reaction Control System (PCRS) Thrusters. Of particular concern is deep cracking in this area which could lead to combustion leakage in the event of through wall cracking from the relief radius into an acoustic cavity of the combustion chamber. In order to reliably detect such defects while ensuring minimal false positives during inspection, the Orthogonal Probe Eddy Current (OPEC) system has been developed and an extensive validation study performed. This report describes the validation procedure, sample set, and inspection results as well as comparing validation flaws with the response from naturally occuring damage.

How to fit demand side management (DSM) into current Chinese electricity system reform?

International Nuclear Information System (INIS)

Yu Yongzhen

2012-01-01

DSM is one of the best and most practical policy tools available to China for balancing environmental protection and economic growth. The new round of electricity system reform provides a good opportunity to consolidate and integrate DSM policy and expedite its development and implementation. DSM policy can be upgraded by incorporating it into the current electricity system reform. Comparing the potential acceleration of electricity price reform with the possibility of imposing a System Benefit Charge (SBC), the author argues that support for a SBC would be much easier to gather among policymakers and stakeholders in a short time and would have a much better policy effect in the current situation. The author discusses three kinds of price discrimination related to the DSM development in China: time-based electricity pricing, electricity price discrimination for industrial structure adjustment in China (Fujian Province as a case), and direct power purchases by large customers and preferential tariff policy. These can be well designed to be combined with DSM and energy efficiency policy. - Highlights: ► Elements of DSM have been in place since 1993, but without even and reinforced policy. ► DSM can be upgraded by fitting it into current Chinese electricity system reform. ► Both electricity price reform and SBC would mean increases in electricity payment. ►Imposing SBC is much easier and better than speeding up electricity price reform. ► Three kinds of price discrimination can be well designed to be combined with DSM.

The opinion of Turkish cardiologists on current malpractice system and an alternative patient compensation system proposal: PCS study group.

Science.gov (United States)

Olcay, Ayhan; Emren, Sadık Volkan; Babür Güler, Gamze; Güler, Ekrem; Ertunç, Vedat; Berilgen, Rida; Aslan, Abdullah; Şimşek, Ersin Çağrı; Gölcük, Şükriye Ebru; Yalın, Kıvanç

2017-10-01

Cardiologists participate in the diagnosis and interventional treatment of numerous high-risk patients. The goal of this study was to investigate how the current malpractice system in Turkey influences cardiologists' diagnostic and interventional behavior and to obtain their opinions about an alternative patient compensation system. The present cross-sectional study assessed the practice of defensive medicine among cardiologists who are actively working in various types of workplace within the Turkish healthcare system. A 24-item questionnaire was distributed to cardiology residents, specialists, and academics in Turkey in print format, by electronic mail, or via cell phone message. A total of 253 cardiologists responded to the survey. Among them, 29 (11.6%) had been sued for malpractice claims in the past. Of the cardiologists who had been sued, 2 (6.9%) had been ordered to pay financial compensation, and 1 (3.4%) was given a sentence of imprisonment due to negligence. In all, 132 (52.8%) of the surveyed cardiologists reported that they had changed their practices due to fear of litigation, and 232 (92.8%) reported that they would prefer the new proposed patient compensation system to the current malpractice system. Among the cardiologists surveyed, 78.8% indicated that malpractice fear had affected their decision-making with regard to requesting computed tomography angiography or thallium scintigraphy, 71.6% for coronary angiography, 20% for stent implantation, and 83.2% for avoiding treating high-risk patients. The results of this survey demonstrated that cardiologists may request unnecessary tests and perform unneeded interventions due to the fear of malpractice litigation fear. Many also avoid high-risk patients and interventions. The majority indicated that they would prefer the proposed alternative patient compensation system to the current malpractice system.

Smart grids in the colombian electric system: Current situation and potential opportunities

Directory of Open Access Journals (Sweden)

William Mauricio Giral Ramírez

2017-07-01

Full Text Available Context: This paper focuses on providing a functional analysis of smart grids, with the purpose of establishing a framework to identify the main characteristics of the current electric interconnection system in Colombia. It also names the positive incentives proposed by the Colombian government to support both research and development projects that implement non-conventional energy sources and promoting energy management based on efficiency. Method: An architecture model that describes the components interoperability of a smart grid is presented using a descriptive methodology. Results: The results include a list of the objectives established by the Colombian public and private entities related to energy development, specially focusing on the opportunities to provide some kind of artificial intelligence to the current electrical system. Conclusions: It is necessary for the Colombian energy system to supply the energy demand considering electrical safety, social equity, and the minimum environmental impact. These restrictions impose new challenges for the energy system itself: From a technical point of view, the traditional electrical grid must be outfitted with the characteristics of a smart grid, and from a legal perspective, it is essential to generate a clear regulatory framework that promotes the development of this type of technology.

Mathematical analysis and coordinated current allocation control in battery power module systems

Science.gov (United States)

Han, Weiji; Zhang, Liang

2017-12-01

As the major energy storage device and power supply source in numerous energy applications, such as solar panels, wind plants, and electric vehicles, battery systems often face the issue of charge imbalance among battery cells/modules, which can accelerate battery degradation, cause more energy loss, and even incur fire hazard. To tackle this issue, various circuit designs have been developed to enable charge equalization among battery cells/modules. Recently, the battery power module (BPM) design has emerged to be one of the promising solutions for its capability of independent control of individual battery cells/modules. In this paper, we propose a new current allocation method based on charging/discharging space (CDS) for performance control in BPM systems. Based on the proposed method, the properties of CDS-based current allocation with constant parameters are analyzed. Then, real-time external total power requirement is taken into account and an algorithm is developed for coordinated system performance control. By choosing appropriate control parameters, the desired system performance can be achieved by coordinating the module charge balance and total power efficiency. Besides, the proposed algorithm has complete analytical solutions, and thus is very computationally efficient. Finally, the efficacy of the proposed algorithm is demonstrated using simulations.

Quantization of interface currents

Energy Technology Data Exchange (ETDEWEB)

Kotani, Motoko [AIMR, Tohoku University, Sendai (Japan); Schulz-Baldes, Hermann [Department Mathematik, Universität Erlangen-Nürnberg, Erlangen (Germany); Villegas-Blas, Carlos [Instituto de Matematicas, Cuernavaca, UNAM, Cuernavaca (Mexico)

2014-12-15

At the interface of two two-dimensional quantum systems, there may exist interface currents similar to edge currents in quantum Hall systems. It is proved that these interface currents are macroscopically quantized by an integer that is given by the difference of the Chern numbers of the two systems. It is also argued that at the interface between two time-reversal invariant systems with half-integer spin, one of which is trivial and the other non-trivial, there are dissipationless spin-polarized interface currents.

Hormone profile in juvenile systemic lupus erythematosus with previous or current amenorrhea

NARCIS (Netherlands)

Silva, Clovis A.; Deen, Maria E. J.; Febronio, Marilia V.; Oliveira, Sheila K.; Terreri, Maria T.; Sacchetti, Silvana B.; Sztajnbok, Flavio R.; Marini, Roberto; Quintero, Maria V.; Bica, Blanca E.; Pereira, Rosa M.; Bonfa, Eloisa; Ferriani, Virginia P.; Robazzi, Teresa C.; Magalhaes, Claudia S.; Hilario, Maria O.

To identify the underlying mechanism of amenorrhea in juvenile systemic lupus erythematosus (JSLE) patients, thirty-five (11.7%) JSLE patients with current or previous amenorrhea were consecutively selected among the 298 post-menarche patients followed in 12 Brazilian pediatric rheumatology centers.

New eddy current testing system in steam generator tubes

International Nuclear Information System (INIS)

Nagata, Yasuyuki; Shimone, Junri; Maeda, Kotaro; Harada, Yutaka; Murakami, Ryuji

2003-01-01

Eddy Current Testing (ECT) technique is applied to PWR Steam Generator (SG) tubes during refueling outage inspection. Bobbin type probe is generally used for the inspection, but it cannot provide sufficient detectability for very tight cracks. NEL, R/D Tech (Canada) and AECL (Canada) jointly developed new ECT probe. The probe is transmit and receive type array probe. It has axial defect detection mode and circumferential defect detection mode. Its inspection speed is as fast as conventional bobbin probe, and detectability performance is same or better than performance of rotating pancake coil (RPC) probe, which is used for detailed inspection. As a tester of the new probe, we have developed new ECT tester TC7700. It is able to transmit composite wave from the 4 independent oscillators (simultaneous excitation system) compared with the conventional inspection system. As regarding for field inspection system, we have integrated Zetec (USA) probe positioner, probe pusher and R/D Tech TC7700. We are also developing new analysis software. The software has automated data screening function, which can deal with large amount of data compared with conventional bobbin probe. We plan to perform a large-scale field trial using the probe and new system in near future. (author)

Staffing Patterns in Public School Systems: Current Status and Trends, Update 2001. Research Snapshot.

Science.gov (United States)

Williams, Alicia D.; Protheroe, Nancy; Parks, Michael C.

Staffing patterns in American public-school systems are presented in this report of the 2000-01 school year. The report addresses the following: why information about staffing ratios is important; how many people currently work in public schools; what proportion of these are teachers, administrators, and support staff; current staffing patterns in…

Study of electromagnetic interference on quench detecting system of HTS current leads for EAST

International Nuclear Information System (INIS)

Hu, Yanlan; Li, Jiangang; Ji, Zhenshan; Zhu, C.M.; Zhen, L.G.; Xiao, Y.Z.

2013-01-01

Highlights: • EAST HTS superconducting magnet system shall be operating in a very noisy environment. • Voltage taps will have a lot of inductive voltage induced on them which makes quench detection very difficult. • The noise comes from the coupling between rapid pulsed poloidal coils, and radiation coupling interference associated with EAST heating systems;. • A series of related electromagnetic compatibility simulation tests have been carried out. • Electromagnetic noises are well restrained by choosing proper anti-interference means. -- Abstract: High temperature superconducting (HTS) material B-2223/Ag-Au has been used for EAST poloidal field (PF) coil current leads for reducing construction and operation cost of cryogenic system. The quench propagation velocity of HTS superconducting material is several orders of magnitude lower than that of normal low temperature current leads. It is difficult to detect weak signal of quench which is easily influenced by strong electromagnetic interference (EMI). In this paper, the sources of EMI from quench detecting system of high temperature current leads have been introduced. And we have chosen reasonable methods for good transformation and protection on the basis of electromagnetic compatibility simulation diagnosis experiments. Recent experimental results showed that the restraint of EMI has been achieved and has met the requirements of experiment

Current measurement system utilizing cryogenic techniques for the absolute measurement of the magnetic flux quantum

International Nuclear Information System (INIS)

Endo, T.; Murayama, Y.; Sakamoto, Y.; Sakuraba, T.; Shiota, F.

1989-01-01

A series of systems composed of cryogenic devices such as a Josephson potentiometer and a cryogenic current comparator has been proposed and developed to precisely measure a current with any value up to 1 A. These systems will be used to measure the injected electrical energy with an uncertainty of the order of 0.01 ppm or less in the absolute measurement of the magnetic flux quantum by superconducting magnetic levitation. Some preliminary experiments are described

Design of high current bunching system and high power fast Faraday cup for high current LEBT at VECC

International Nuclear Information System (INIS)

Anuraag Misra, A.; Pandit, B.V.S.; Gautam Pal, C.

2011-01-01

A high current microwave ion source as described is currently operational at VECC. We are able to optimize 6.4 mA of proton current in the LEBT line of ion source. The cyclotron type of accelerators accept only a fraction of DC ion beam coming from ion source so a ion beam buncher is needed to increase the accepted current into the cyclotron. The buncher described in this paper is unique in its kind as it has to handle high beam loading power upto 400 W as it is designed to bunch few mA of proton beam currents at 80 keV beam energy. A sinusoidal quarter wave RF structure has been chosen to bunch the high current beam due to high Q achievable in comparison with other configurations. This buncher has been designed using CST Microwave studio 3D advanced code since the design frequency of our buncher is 42 MHz, we have provided the RF and vacuum window near the drift tube of buncher to avoid vacuum and multipacting problems and to keep maximum volume in air region. There is a provision of multipacting interlocks to shut off amplifier during multipacting. We have carried out a detailed electromagnetic and thermal design of the buncher in CST Microwave studio and simulated values of unloaded Q was calculated be 4000. We have estimated a power of 400 W to achieve gap (designed) voltage of 10 kV. This buncher is in advanced stage of fabrication. A high power fast Faraday cup is also designed to characterize the above mentioned high current bunching system. The fast Faraday cup is designed in 50 Ω coaxial geometry to transmit fast pulse of bunched ion beam. The design of Faraday cup was completed using ANSYS HFSS and a bandwidth of 1.75 GHz was achieved this faraday cup design was different from conventional Faraday cup design as we have designed the support and cooling lines at such a place on Faraday cup which do not disturb the electrical impedance of the cup. (author)

Joint Polar Satellite System (JPSS) Common Ground System (CGS) Current Technical Performance Measures

Science.gov (United States)

Cochran, S.; Panas, M.; Jamilkowski, M. L.; Miller, S. W.

2015-12-01

ABSTRACT The National Oceanic and Atmospheric Administration (NOAA) and National Aeronautics and Space Administration (NASA) are jointly acquiring the next-generation civilian weather and environmental satellite system: the Joint Polar Satellite System (JPSS). The Joint Polar Satellite System will replace the afternoon orbit component and ground processing system of the current Polar-orbiting Operational Environmental Satellites (POES) managed by NOAA. The JPSS satellites will carry a suite of sensors designed to collect meteorological, oceanographic, climatological and geophysical observations of the Earth. The ground processing system for JPSS is known as the JPSS Common Ground System (JPSS CGS). Developed and maintained by Raytheon Intelligence, Information and Services (IIS), the CGS is a multi-mission enterprise system serving NOAA, NASA and their national and international partners. The CGS has demonstrated its scalability and flexibility to incorporate multiple missions efficiently and with minimal cost, schedule and risk, while strengthening global partnerships in weather and environmental monitoring. The CGS architecture is being upgraded to Block 2.0 in 2015 to "operationalize" S-NPP, leverage lessons learned to date in multi-mission support, take advantage of more reliable and efficient technologies, and satisfy new requirements and constraints in the continually evolving budgetary environment. To ensure the CGS meets these needs, we have developed 49 Technical Performance Measures (TPMs) across 10 categories, such as data latency, operational availability and scalability. This paper will provide an overview of the CGS Block 2.0 architecture, with particular focus on the 10 TPM categories listed above. We will provide updates on how we ensure the deployed architecture meets these TPMs to satisfy our multi-mission objectives with the deployment of Block 2.0.

A novel concept of fault current limiter based on saturable core in high voltage DC transmission system

Science.gov (United States)

Yuan, Jiaxin; Zhou, Hang; Gan, Pengcheng; Zhong, Yongheng; Gao, Yanhui; Muramatsu, Kazuhiro; Du, Zhiye; Chen, Baichao

2018-05-01

To develop mechanical circuit breaker in high voltage direct current (HVDC) system, a fault current limiter is required. Traditional method to limit DC fault current is to use superconducting technology or power electronic devices, which is quite difficult to be brought to practical use under high voltage circumstances. In this paper, a novel concept of high voltage DC transmission system fault current limiter (DCSFCL) based on saturable core was proposed. In the DCSFCL, the permanent magnets (PM) are added on both up and down side of the core to generate reverse magnetic flux that offset the magnetic flux generated by DC current and make the DC winding present a variable inductance to the DC system. In normal state, DCSFCL works as a smoothing reactor and its inductance is within the scope of the design requirements. When a fault occurs, the inductance of DCSFCL rises immediately and limits the steepness of the fault current. Magnetic field simulations were carried out, showing that compared with conventional smoothing reactor, DCSFCL can decrease the high steepness of DC fault current by 17% in less than 10ms, which verifies the feasibility and effectiveness of this method.

Development of movable mask system to cope with high beam current

International Nuclear Information System (INIS)

Suetsugu, Y.; Shibata, K.; Sanami, T.; Kageyama, T.; Takeuchi, Y.

2003-01-01

The KEK B factory (KEKB), a high current electron-positron collider, has a movable mask (or collimator) system to reduce the background noise in the BELLE detector coming from spent particles. The early movable masks, however, had severe problems of heating, arcing, and vacuum leaks over the stored beam current of several hundred mA. The cause is intense trapped higher order modes (HOMs) excited at the mask head, where the cross section of the beam chamber changed drastically. The mask head, made of copper-tungsten alloy or pure copper, was frequently damaged by hitting of the high energy beam at the same time. Since the problems of the mask were revealed, several kinds of improved masks have been designed employing rf technologies in dealing with the HOM and installed to the ring step by step. Much progress has come from adopting a trapped-mode free structure, where the mask was a bent chamber itself. Recently the further improved mask with a reduced HOM design or HOM dampers was developed to suppress the heating of vacuum components near the mask due to the HOM traveling from the mask. To avoid damage to the mask head, on the other hand, a titanium mask head was tried. The latest masks are working as expected now at the stored beam current of 1.5 A. Presented are the problems and experiences on the movable mask system for the KEKB, which are characteristic of and common in a high intensity accelerator

Predictive Pulse Pattern Current Modulation Scheme for Harmonic Reduction in Three-Phase Multidrive Systems

DEFF Research Database (Denmark)

Davari, Pooya; Yang, Yongheng; Zare, Firuz

2016-01-01

at the rectification stage to synthesize sinusoidal input currents. The input voltage sensing is avoided in order to minimize the number of required sensors, and the grid synchronization also has been implemented based on a common Phase-Locked-Loop (PLL) using the DC-link capacitor voltage ripple. Experimental results......The majority of the industrial motor drive systems are equipped with the conventional line-commutated front-end rectifiers, and being one of the main sources of harmonics in the power line. While a parallel combination of these drive units elevates current quality issues, a proper arrangement...... of them can lead to the cancellation of specific harmonics. This paper proposes a new cost-effective harmonic mitigation solution for multi-drive systems using a predictive pulse pattern current modulation control strategy. The proposed technique applies suitable interaction among parallel drive units...

Multichannel computerized control system of current pulses in LIU-30 electron accelerator

CERN Document Server

Gerasimov, A I; Kulgavchuk, V V; Pluzhnikov, A V

2002-01-01

In LIU-30 power linear pulsed induction electron accelerator (40 MeV, 10 kA, 25 ns) 288 radial lines with water insulation serve as energy accumulators and shapers of accelerating voltage pulses. The lines are charged simultaneously up to 500 kV using a system comprising 72 Arkadiev-Marx screened generators. To control parameter of synchronous pulses of charging current with up to 60 kA amplitude and 0.85 mu s duration in every of 72 charging circuits one applies a computer-aided system. Current pulse is recorded at output of every generator using the Rogowski coil signal from which via a cable line is transmitted to an analog-digital converter, is processed with 50 ns sampling and is recorded to a memory unit. Upon actuation of accelerator the signals are sequentially or selectively displayed and are compared with pulse typical shape

Development of a diagnostic expert system for eddy current data analysis using applied artificial intelligence methods

International Nuclear Information System (INIS)

Upadhyaya, B.R.; Yan, W.; Henry, G.

1999-01-01

A diagnostic expert system that integrates database management methods, artificial neural networks, and decision-making using fuzzy logic has been developed for the automation of steam generator eddy current test (ECT) data analysis. The new system, known as EDDYAI, considers the following key issues: (1) digital eddy current test data calibration, compression, and representation; (2) development of robust neural networks with low probability of misclassification for flaw depth estimation; (3) flaw detection using fuzzy logic; (4) development of an expert system for database management, compilation of a trained neural network library, and a decision module; and (5) evaluation of the integrated approach using eddy current data. The implementation to field test data includes the selection of proper feature vectors for ECT data analysis, development of a methodology for large eddy current database management, artificial neural networks for flaw depth estimation, and a fuzzy logic decision algorithm for flaw detection. A large eddy current inspection database from the Electric Power Research Institute NDE Center is being utilized in this research towards the development of an expert system for steam generator tube diagnosis. The integration of ECT data pre-processing as part of the data management, fuzzy logic flaw detection technique, and tube defect parameter estimation using artificial neural networks are the fundamental contributions of this research. (orig.)

Development of a diagnostic expert system for eddy current data analysis using applied artificial intelligence methods

Energy Technology Data Exchange (ETDEWEB)

Upadhyaya, B.R.; Yan, W. [Tennessee Univ., Knoxville, TN (United States). Dept. of Nuclear Engineering; Behravesh, M.M. [Electric Power Research Institute, Palo Alto, CA (United States); Henry, G. [EPRI NDE Center, Charlotte, NC (United States)

1999-09-01

A diagnostic expert system that integrates database management methods, artificial neural networks, and decision-making using fuzzy logic has been developed for the automation of steam generator eddy current test (ECT) data analysis. The new system, known as EDDYAI, considers the following key issues: (1) digital eddy current test data calibration, compression, and representation; (2) development of robust neural networks with low probability of misclassification for flaw depth estimation; (3) flaw detection using fuzzy logic; (4) development of an expert system for database management, compilation of a trained neural network library, and a decision module; and (5) evaluation of the integrated approach using eddy current data. The implementation to field test data includes the selection of proper feature vectors for ECT data analysis, development of a methodology for large eddy current database management, artificial neural networks for flaw depth estimation, and a fuzzy logic decision algorithm for flaw detection. A large eddy current inspection database from the Electric Power Research Institute NDE Center is being utilized in this research towards the development of an expert system for steam generator tube diagnosis. The integration of ECT data pre-processing as part of the data management, fuzzy logic flaw detection technique, and tube defect parameter estimation using artificial neural networks are the fundamental contributions of this research. (orig.)

Architecture and control of a high current ion implanter system

International Nuclear Information System (INIS)

Bayer, E.H.; Paul, L.F.; Kranik, J.R.

1979-01-01

The design of an ion implant system for use in production requires that special attention be given to areas of design which normally are not emphasized on research or development type ion implanters. Manually operated, local controls are replaced by remote controls, automatic sequencing, and digital displays. For ease of maintenance and replication the individual components are designed as simply as possible and are contained in modules of separate identities, joined only by the beam line and electrical interconnections. A production environment also imposes requirements for the control of contamination and maintainability of clean room integrity. For that reason the major portion of the hardware is separated from the clean operator area and is housed in a maintenance core area. The controls of a production system should also be such that relatively unskilled technicians are able to operate the system with optimum repeatability and minimum operator intervention. An extensive interlock system is required. Most important, for use in production the ion implant system has to have a relatively high rate of throughput. Since the rate of throughput at a given dose is a function of beam current, pumpdown time and wafer handling capacity, design of components affecting these parameters has been optimized. Details of the system are given. (U.K.)

Public health services and systems research: current state of finance research.

Science.gov (United States)

Ingram, Richard C; Bernet, Patrick M; Costich, Julia F

2012-11-01

There is a growing recognition that the US public health system should strive for efficiency-that it should determine the optimal ways to utilize limited resources to improve and protect public health. The field of public health finance research is a critical part of efforts to understand the most efficient ways to use resources. This article discusses the current state of public health finance research through a review of public health finance literature, chronicles important lessons learned from public health finance research to date, discusses the challenges faced by those seeking to conduct financial research on the public health system, and discusses the role of public health finance research in relation to the broader endeavor of Public Health Services and Systems Research.

Compensation methods applied in current control schemes for large AC drive systems

DEFF Research Database (Denmark)

Rus, D. C.; Preda, N. S.; Teodorescu, Remus

2012-01-01

The paper deals with modified PI current control structures for large AC drive systems which use surface mounted permanent magnet synchronous machines or squirrel-cage induction motors supplied with voltage source inverters. In order to reduce the power losses caused by high frequency switching...

X-ray tube current control

International Nuclear Information System (INIS)

Dupuis, W.A.; Resnick, T.A.

1982-01-01

A closed loop feedback system for controlling the current output of an x-ray tube. The system has circuitry for improving the transient response and stability of the x-ray tube current over a substantial nonlinear portion of the tube current production characteristic. The system includes a reference generator for applying adjustable step function reference signals representing desired tube currents. The system also includes means for instantaneous sensing of actual tube current. An error detector compares the value of actual and reference tube current and produces an error signal as a function of their difference. The system feedback loop includes amplification circuitry for controlling x-ray tube filament dc voltage to regulate tube current as a function of the error signal value. The system also includes compensation circuitry, between the reference generator and the amplification circuitry, to vary the loop gain of the feedback control system as a function of the reference magnitude

A current controlled matrix converter for wind energy conversion systems based on permanent magnet synchronous generator

Directory of Open Access Journals (Sweden)

Naggar H. Saad

2016-05-01

Full Text Available The main challenges of wind energy conversion systems (WECS are to maximize the energy capture from the wind and injecting reactive power during the fault. This paper presents a current controlled matrix converter to interface Permanent Magnet Synchronous Generators (PMSG based WECS with the grid. To achieve fast dynamic response with reduced current ripples, a hysteresis current control is utilized. The proposed control system decouples the active and reactive components of the PMSG current to extract the maximum power from the wind at a given wind velocity and to inject reactive power to the grid. Reactive power injection during the fault satisfying the grid-codes requirement. The proposed WECS has been modeled and simulated using PSCAD/EMTDC software package.

Real time data acquisition system for the High Current Test Facility proton accelerator

International Nuclear Information System (INIS)

Langlais, C.E.; Erickson, P.D.; Caissie, L.P.

1975-01-01

A real time data acquisition system was developed to monitor and control the High Current Test Facility Proton Accelerator. It is a PDP-8/E computer system with virtual memory capability that is fully interrupt driven and operates under a real-time, multi-tasking executive. The application package includes mode selection to automatically modify programs and optimize operation under varying conditions. (U.S.)

A Method for Eddy Current Field Measurement in Permanent Magnet Magnetic Resonance Imaging Systems

Directory of Open Access Journals (Sweden)

SONG Rui

2018-03-01

Full Text Available Magnetic resonance imaging (MRI is a widely used medical imaging technique. In MRI system, gradient magnetic fields are used to code spatial information. However, the fast-switching electric currents in the gradients coils used to generate gradient fields also induce vortex electric field, often referred as eddy current, in the surrounding metal conductors. In this paper, a method for eddy current field measurement was proposed. Based on the Faraday law of electromagnetic induction, an eddy current field measuring device was designed. Combining hardware acquisition and software processing, the eddy current field was obtained by subtracting the ideal gradient field from the magnetic field measured experimentally, whose waveform could be displayed in real time. The proposed method was verified by experimental results.

Transcranial Direct Current Stimulation in Tinnitus Patients: A Systemic Review and Meta-Analysis

Directory of Open Access Journals (Sweden)

Jae-Jin Song

2012-01-01

Full Text Available Although transcranial direct current stimulation (tDCS has already been used to manage tinnitus patients, paucity of reports and variations in protocols preclude a comprehensive understanding. Hence, we conducted a meta-analysis based on systemic review to assess effectiveness of tDCS in tinnitus management and to compare stimulation parameters. PubMed was searched for tDCS studies in tinnitus. For randomized controlled trials (RCTs, a meta-analysis was performed. A total of 17 studies were identified and 6 of them were included in the systemic review and 2 RCTs were included in the meta-analysis. Overall 39.5% responded to active tDCS with a mean tinnitus intensity reduction of 13.5%. Additionally, left temporal area (LTA and bifrontal tDCS indicated comparable results. Active tDCS was found to be more effective than sham tDCS for tinnitus intensity reduction (Hedges' g=.77, 95% confidence interval 0.23–1.31. The efficacy of tDCS in tinnitus could not be fully confirmed by the current study because of the limited number of studies, but all studies included in the current systemic review and meta-analysis demonstrated significant tinnitus intensity improvement. Therefore, tDCS may be a promising tool for tinnitus management. Future RCTs in a large series regarding the efficacy as well as the comparison between LTA- and bifrontal tDCS are recommended.

Optimized design of resonant controller for stator current harmonic compensation in DFIG wind turbine systems

DEFF Research Database (Denmark)

Liu, Changjin; Chen, Wenjie; Blaabjerg, Frede

2012-01-01

This paper presents an analytical method to optimize the parameters of resonant controller which is used in a Doubly-Fed Induction Generator (DFIG). In the DFIG control system, the fundamental current loop is controlled by PI-controllers, and the stator harmonic current loop is controlled...

Current State of Technology of Fuel Cell Power Systems for Autonomous Underwater Vehicles

Directory of Open Access Journals (Sweden)

Alejandro Mendez

2014-07-01

Full Text Available Autonomous Underwater Vehicles (AUVs are vehicles that are primarily used to accomplish oceanographic research data collection and auxiliary offshore tasks. At the present time, they are usually powered by lithium-ion secondary batteries, which have insufficient specific energies. In order for this technology to achieve a mature state, increased endurance is required. Fuel cell power systems have been identified as an effective means to achieve this endurance but no implementation in a commercial device has yet been realized. This paper summarizes the current state of development of the technology in this field of research. First, the most adequate type of fuel cell for this application is discussed. The prototypes and design concepts of AUVs powered by fuel cells which have been developed in the last few years are described. Possible commercial and experimental fuel cell stack options are analyzed, examining solutions adopted in the analogous aerial vehicle applications, as well as the underwater ones, to see if integration in an AUV is feasible. Current solutions in oxygen and hydrogen storage systems are overviewed and energy density is objectively compared between battery power systems and fuel cell power systems for AUVs. A couple of system configuration solutions are described including the necessary lithium-ion battery hybrid system. Finally, some closing remarks on the future of this technology are given.

Reflecting on the mirror neuron system in autism: a systematic review of current theories.

Science.gov (United States)

Hamilton, Antonia F de C

2013-01-01

There is much interest in the claim that dysfunction of the mirror neuron system in individuals with autism spectrum condition causes difficulties in social interaction and communication. This paper systematically reviews all published studies using neuroscience methods (EEG/MEG/TMS/eyetracking/EMG/fMRI) to examine the integrity of the mirror system in autism. 25 suitable papers are reviewed. The review shows that current data are very mixed and that studies using weakly localised measures of the integrity of the mirror system are hard to interpret. The only well localised measure of mirror system function is fMRI. In fMRI studies, those using emotional stimuli have reported group differences, but studies using non-emotional hand action stimuli do not. Overall, there is little evidence for a global dysfunction of the mirror system in autism. Current data can be better understood under an alternative model in which social top-down response modulation is abnormal in autism. The implications of this model and future research directions are discussed. Copyright © 2012 Elsevier Ltd. All rights reserved.

Current understanding of interactions between nanoparticles and the immune system.

Science.gov (United States)

Dobrovolskaia, Marina A; Shurin, Michael; Shvedova, Anna A

2016-05-15

The delivery of drugs, antigens, and imaging agents benefits from using nanotechnology-based carriers. The successful translation of nanoformulations to the clinic involves thorough assessment of their safety profiles, which, among other end-points, includes evaluation of immunotoxicity. The past decade of research focusing on nanoparticle interaction with the immune system has been fruitful in terms of understanding the basics of nanoparticle immunocompatibility, developing a bioanalytical infrastructure to screen for nanoparticle-mediated immune reactions, beginning to uncover the mechanisms of nanoparticle immunotoxicity, and utilizing current knowledge about the structure-activity relationship between nanoparticles' physicochemical properties and their effects on the immune system to guide safe drug delivery. In the present review, we focus on the most prominent pieces of the nanoparticle-immune system puzzle and discuss the achievements, disappointments, and lessons learned over the past 15years of research on the immunotoxicity of engineered nanomaterials. Copyright © 2016 Elsevier Inc. All rights reserved.

Discrete changes of current statistics in periodically driven stochastic systems

International Nuclear Information System (INIS)

Chernyak, Vladimir Y; Sinitsyn, N A

2010-01-01

We demonstrate that the counting statistics of currents in periodically driven ergodic stochastic systems can show sharp changes of some of its properties in response to continuous changes of the driving protocol. To describe this effect, we introduce a new topological phase factor in the evolution of the moment generating function which is akin to the topological geometric phase in the evolution of a periodically driven quantum mechanical system with time-reversal symmetry. This phase leads to the prediction of a sign change for the difference of the probabilities to find even and odd numbers of particles transferred in a stochastic system in response to cyclic evolution of control parameters. The driving protocols that lead to this sign change should enclose specific degeneracy points in the space of control parameters. The relation between the topology of the paths in the control parameter space and the sign changes can be described in terms of the first Stiefel–Whitney class of topological invariants. (letter)

Comparative analysis of current payment system for hospital services in Serbia and projected payments under diagnostic related groups system in urology

Directory of Open Access Journals (Sweden)

Babić Uroš

2015-01-01

Full Text Available Background/Aim. Global budget per calendar year is a traditional method of funding hospitals in Serbia. Diagnose related groups (DGR is a method of hospital payment based on classification of patients into groups with clinically similar problems and similar utilization of hospital resources. The aim of this study was to compare current methods of hospital services payment with the projected costs by DRG payment method in urology. Methods. The data were obtained from the information system used in the Clinical Hospital Center “Dr. Dragiša Mišović” - Dedinje in Belgrade, Serbia. The implemented hospital information system was the main criterion for selection of healthcare institutions. The study included 994 randomly selected patients treated surgically and conservatively in 2012. Results. Average costs under the current payment method were slightly higher than those projected by DRG, however, the variability was twice as high (54,111 ± 69,789 compared to 53,434 ± 32,509, p < 0,001 respectively. The univariate analysis showed that the highest correlation with the current payment method as well as with the projected one by DRG was observed in relation to the number of days of hospitalization (ρ = 0.842, p < 0.001, and ρ = 0.637, p < 0.001, respectively. Multivariate regression models confirmed the influence of the number of hospitalization days to costs under the current payment system (β = 0.843, p < 0.001 as well as under the projected DRG payment system (β = 0.737, p < 0.001. The same predictor was crucial for the difference in the current payment method and the projected DRG payment methods (β = 0.501, p <0.001. Conclusion. Payment under the DRG system is administratively more complex because it requires detailed and standardized coding of diagnoses and procedures, as well as the information on the average consumption of resources (costs per DRG. Given that aggregate costs of treatment under two hospital payment methods compared

Observations of the southern East Madagascar Current and undercurrent and countercurrent system

Science.gov (United States)

Nauw, J. J.; van Aken, H. M.; Webb, A.; Lutjeharms, J. R. E.; de Ruijter, W. P. M.

2008-08-01

In April 2001 four hydrographic sections perpendicular to the southern East Madagascar Current were surveyed as part of the Agulhas Current Sources Experiment. Observations with a vessel mounted and a lowered ADCP produced information on the current field while temperature, salinity, oxygen and nutrient data obtained with a CTD-Rosette system, gave information on the water mass structure of the currents southeast of Madagascar. The peak velocity in the pole-ward East Madagascar Current through these four sections had a typical magnitude of ˜110 cm/s, while the width of this current was of the order of 120 km. The mean pole-ward volume transport rate of this current during the survey above the 5°C isotherm was estimated to be 37 ± 10 Sv. On all four sections an undercurrent was observed at intermediate depths below the East Madagascar Current. Its equator-ward transport rate amounted to 2.8 ± 1.4 Sv. Offshore of the East Madagascar Current the shallow South Indian Ocean Countercurrent was observed. This eastward frontal jet coincided with the barotropic and thermohaline front that separates the saline Subtropical Surface Water from the fresher Tropical Surface Water in the East Madagascar Current. The near-surface geostrophic flow of the East Madagascar Current, derived from satellite altimetry data from 1992 to 2005, suggests a strong variability of this transport due to eddy variability and interannual changes. The long-term pole-ward mean transport of the East Madagascar Current, roughly estimated from those altimetry data amounts to 32 Sv. The upper-ocean water mass of the East Madagascar Current was very saline in 2001, compared to WOCE surveys from 1995. Comparison of our undercurrent data with those of the WOCE surveys in 1995 confirms that the undercurrent is a recurrent feature. Its water mass properties are relatively saline, due to the presence of water originating from the Red Sea outflow at intermediate levels. The saline water was advected from the

Mouse housing system using pressurized cages intraventilated by direct-current microfans.

Science.gov (United States)

Martinewski, Alexandre; Correia, Caio S C; de Souza, Nívea L; Merusse, José L B

2012-03-01

We performed the initial assessment of an alternative pressurized intraventilated (PIV) caging system for laboratory mice that uses direct-current microfans to achieve cage pressurization and ventilation. Twenty-nine pairs of female SPF BALB/c mice were used, with 19 experimental pairs kept in PIV cages and 10 control pairs kept in regular filter-top (FT) cages. Both groups were housed in a standard housing room with a conventional atmospheric control system. For both systems, intracage temperatures were in equilibrium with ambient room temperature. PIV cages showed a significant difference in pressure between days 1 and 8. Air speed (and consequently airflow rate) and the number of air changes hourly in the PIV cages showed decreasing trends. In both systems, ammonia concentrations increased with time, with significant differences between groups starting on day 1. Overall, the data revealed that intracage pressurization and ventilation by using microfans is a simple, reliable system, with low cost, maintenance requirements, and incidence of failures. Further experiments are needed to determine the potential influence of this system on the reproductive performance and pulmonary integrity in mice.

Detection of radiation from a heated and modulated equatorial electrojet current system

International Nuclear Information System (INIS)

Lunnen, R.J.; Lee, H.S.; Ferraro, A.J.; Collins, T.W.

1984-01-01

In May 1983, ionospheric heating experiments were conducted using the very high frequency radar facility at Lima, Peru. Experiments involving high frequency heating of the ionosphere were successfully conducted during 1982 at Islote, Puerto Rico. These local experiments had characterized the signal radiated from a heated and modulated ionospheric current system near the mid-latitudes. A long-path signal had also been received in September 1982 at Salinas, Puerto Rico from a mid-day equatorial electrojet, heated and modulated by the Jicamarca facility. The authors have investigated the characteristics of the local signal that would be radiated from a strong equatorial electrojet when heated and modulated, and report here that at the geomagnetic equator they were similar to, but less intense than, those observed at Arecibo, Puerto Rico due to parameter differences. This radiation is believed to be the first detected from a heated and modulated equatorial electrojet current system in the Western Hemisphere. (author)

Physical connectivity between Pulley Ridge and Dry Tortugas coral reefs under the influence of the Loop Current/Florida Current system

Science.gov (United States)

Kourafalou, V. H.; Androulidakis, Y. S.; Kang, H.; Smith, R. H.; Valle-Levinson, A.

2018-07-01

The Pulley Ridge and Dry Tortugas coral reefs are among the most pristine, but also fragile, marine ecosystems of the continental United States. Understanding connectivity processes between them and with surrounding shelf and deep areas is fundamental for their management. This study focuses on the physical processes related to the connectivity of these reefs. Unprecedented in situ time series were used at these specific reef locations, together with satellite observations and numerical simulations, to investigate the dynamics controlling local circulation on the Southwestern Florida Shelf (SWFS) under oceanic influence. The approach of the Loop Current and Florida Current (LC/FC) system to the SWFS slope can induce 0.5 to 1 m/s offshore flows impacting the Pulley Ridge and Dry Tortugas reefs. On the other hand, when the LC/FC system retreats from the slope, onshore flows can carry open-sea waters over the coral reefs. Local formation of cyclonic eddies is possible near the Dry Tortugas reefs in the LC approach case and passage of upstream LC Frontal Eddies is possible in the LC retreat case. Offshore currents ∼1 m/s over the SWFS slope were also found during periods of anticyclonic LC Eddy separation. A novel finding is the shedding and northward propagation of mesoscale anticyclonic eddies from the core of the LC along the West Florida Shelf. Eddy shedding may have a broader effect on the dynamics of the shelf around the study reef areas. Long periods of LC/FC domination over these coral reefs (reaching several weeks to months) are characterized by strong (∼1 m/s) along-shelf currents and continuous upwelling processes, which may weaken the slope stratification and bring colder, deeper waters over the shelf-break and toward the shallower shelf region.

Unfolded Equations for Current Interactions of 4d Massless Fields as a Free System in Mixed Dimensions

CERN Document Server

Gelfond, O A

2015-01-01

Interactions of massless fields of all spins in four dimensions with currents of any spin is shown to result from a solution of the linear problem that describes a gluing between rank-one (massless) system and rank-two (current) system in the unfolded dynamics approach. Since the rank-two system is dual to a free rank-one higher-dimensional system, that effectively describes conformal fields in six space-time dimensions, the constructed system can be interpreted as describing a mixture between linear conformal fields in four and six dimensions. Interpretation of the obtained results in spirit of AdS/CFT correspondence is discussed.

The differential Howland current source with high signal to noise ratio for bioimpedance measurement system

Energy Technology Data Exchange (ETDEWEB)

Liu, Jinzhen; Li, Gang; Lin, Ling, E-mail: linling@tju.edu.cn [State Key Laboratory of Precision Measurement Technology and Instruments, Tianjin University, Tianjin, People' s Republic of China, and Tianjin Key Laboratory of Biomedical Detecting Techniques and Instruments, Tianjin University, Tianjin (China); Qiao, Xiaoyan [College of Physics and Electronic Engineering, Shanxi University, Shanxi (China); Wang, Mengjun [School of Information Engineering, Hebei University of Technology, Tianjin (China); Zhang, Weibo [Institute of Acupuncture and Moxibustion China Academy of Chinese Medical Sciences, Beijing (China)

2014-05-15

The stability and signal to noise ratio (SNR) of the current source circuit are the important factors contributing to enhance the accuracy and sensitivity in bioimpedance measurement system. In this paper we propose a new differential Howland topology current source and evaluate its output characters by simulation and actual measurement. The results include (1) the output current and impedance in high frequencies are stabilized after compensation methods. And the stability of output current in the differential current source circuit (DCSC) is 0.2%. (2) The output impedance of two current circuits below the frequency of 200 KHz is above 1 MΩ, and below 1 MHz the output impedance can arrive to 200 KΩ. Then in total the output impedance of the DCSC is higher than that of the Howland current source circuit (HCSC). (3) The SNR of the DCSC are 85.64 dB and 65 dB in the simulation and actual measurement with 10 KHz, which illustrates that the DCSC effectively eliminates the common mode interference. (4) The maximum load in the DCSC is twice as much as that of the HCSC. Lastly a two-dimensional phantom electrical impedance tomography is well reconstructed with the proposed HCSC. Therefore, the measured performance shows that the DCSC can significantly improve the output impedance, the stability, the maximum load, and the SNR of the measurement system.

Advanced alarm system design and human performance: Guidance development and current research

Energy Technology Data Exchange (ETDEWEB)

O` Hara, J M [Brookhaven National Lab., Upton, NY (United States)

1997-09-01

This paper describes a research program sponsored by the U.S. Nuclear Regulatory Commission to address the human factors engineering (HFE) aspects of nuclear power plant alarm systems. The overall objective of the program is to develop HFE review guidance for advanced alarm systems. Guidance has been developed based on a broad base of technical and research literature. As part of the development effort, aspects of alarm system design for which the technical basis was insufficient to support guidance development were identified and prioritized. Research is currently underway to address the highest priority topics: alarm processing and display characteristics. (author). 29 refs, 2 figs.

Advanced alarm system design and human performance: Guidance development and current research

International Nuclear Information System (INIS)

O'Hara, J.M.

1997-01-01

This paper describes a research program sponsored by the U.S. Nuclear Regulatory Commission to address the human factors engineering (HFE) aspects of nuclear power plant alarm systems. The overall objective of the program is to develop HFE review guidance for advanced alarm systems. Guidance has been developed based on a broad base of technical and research literature. As part of the development effort, aspects of alarm system design for which the technical basis was insufficient to support guidance development were identified and prioritized. Research is currently underway to address the highest priority topics: alarm processing and display characteristics. (author). 29 refs, 2 figs

The trend of the research and development for the upgrade of the high current energy system

International Nuclear Information System (INIS)

2010-01-01

The high current energy technology ranges from a basic technology of the electric power field to a state-of-the-art technology and has been used extremely variously. In addition, as the energy technology advances, the expansion of applied field, such as the nuclear fusion and the exhaust thing processing, etc., requires a further upgrade of the large current technology. In this report, the trend of the research and development for the upgrade of the high current energy technology are summarized. In the following, the elemental technology including arc/plasma phenomena and the pulse power system is described in Chapter 2. In Chapter 3, the trend of the research and development for the upgrade of various equipments and devices such as the nuclear fusion development, the superconducting applications of SMES and the maglev transportation system, and the arc application of the exhaust processing for a medical waste, the radio active waste and a detrimental gas and the next generation lithography system. In Chapter 4, the analysis and the measurement technology of the arc phenomenon and the standardization of current shunt, etc are described. We hope this research report can contribute to the promotion of technical exchanges in different fields, and offer guidelines for future development in this high current energy technology. (author)

Current status of nuclear power plant I and C systems (2000)

Energy Technology Data Exchange (ETDEWEB)

Lee, Dong Young; Park, J.H.; Lee, J.S. and others

2000-12-01

Analog type I and C Systems of Nuclear Power Plants are being replaced by digital type systems because of the aging problems of the I and C systems. New NPPs have adopted computer-based digital I and C systems because the economical efficiency and the usability of the systems become higher than the analog I and C systems. However, the digital I and C systems have not been applied to NPPs because the reliability of computer systems and software has not been validated. The research works for reliability of the systems have been performed in many institutions. In this study, we reviewed the current status of I and C systems for advanced NPPs that have developed in Korea as well as in other countries until this year. We hope to use the result of this study to plan for a localization of NPP I and C systems. In this study, the I and C systems of advanced reactors such as AP600 and NUPLEX 80+ of U.S.A, CANDU 9 of Canada, APWRs and ABWRs of Japan, N4 of France, and KNGR, KALIMER, and SMART of Korea were reviewed. We reviewed the nuclear policy of U.S.A and Europe, and the NPP digital I and C systems developed in many international research institutes. Using this result, we extracted items to be researched and classified those by types of reactors. Then, we established the localization method of NPP digital I and C systems.

Current status of nuclear power plant I and C systems (2000)

International Nuclear Information System (INIS)

Lee, Dong Young; Park, J. H.; Lee, J. S. and others

2000-12-01

Analog type I and C Systems of Nuclear Power Plants are being replaced by digital type systems because of the aging problems of the I and C systems. New NPPs have adopted computer-based digital I and C systems because the economical efficiency and the usability of the systems become higher than the analog I and C systems. However, the digital I and C systems have not been applied to NPPs because the reliability of computer systems and software has not been validated. The research works for reliability of the systems have been performed in many institutions. In this study, we reviewed the current status of I and C systems for advanced NPPs that have developed in Korea as well as in other countries until this year. We hope to use the result of this study to plan for a localization of NPP I and C systems. In this study, the I and C systems of advanced reactors such as AP600 and NUPLEX 80+ of U.S.A, CANDU 9 of Canada, APWRs and ABWRs of Japan, N4 of France, and KNGR, KALIMER, and SMART of Korea were reviewed. We reviewed the nuclear policy of U.S.A and Europe, and the NPP digital I and C systems developed in many international research institutes. Using this result, we extracted items to be researched and classified those by types of reactors. Then, we established the localization method of NPP digital I and C systems

Multifrequency eddy-current system for inspection of steam generator turbine

International Nuclear Information System (INIS)

Davis, T.J.

1980-11-01

The objectives of this program were to: determine the maximum advantage of the multifrequency eddy current method for nuclear steam generator tubing inspection; simplify system operating procedures and enhance presentation of mutifrequency data; and evaluate multifrequency methods for inspecting recently encountered types of anomalies such as circumferential cracks, inside diameter flaws, and flaws in dented regions. New test methods developed under the program have resulted in a dramatic improvement over earlier multifrequency work. The methods rely on judicious selection of test frequencies and the simultaneous use of differential and absolute multiparameter inspection. Flaws may be sized and profiled with increased accuracy over that of the single-frequency method, and improved rejection of indications from unwanted parameters such as support plates and probe wobble has been obtained. The ability to detect and size support cracks in both corroded and non-corroded supports has been demonstrated on a laboratory basis. A field-usable test system employing four test frequencies was developed under the program and has been evaluated in the EPRI steam generator mockup. Some of the new technology used in this system has been commercialized into the new Zetec MIZ-12 multifrequency system

The Unsinkable Aircraft Carrier: An American Response to the Chinese Anti-Access/Area Denial (A2/AD) Challenge

Science.gov (United States)

2013-04-01

Graduation Requirements Advisor: Dr. Jeffrey M. Reilly Maxwell Air Force Base, Alabama April 2013 DISTRIBUTION A. Approved for public release... Distribution unlimited Maj. John O. Birkeland CDOS Research Paper CDOS Seminar 1 ii Disclaimer The views expressed on this...Battalion-71 st Artillery to Taiwan with the new Nike -Hercules missile batteries. 121 The idea of an active defense against missiles has been

Dynamics of the Josephson multi-junction system with junctions characterized by non-sinusoidal current - phase relationship

International Nuclear Information System (INIS)

Abal'osheva, I.; Lewandowski, S.J.

2004-01-01

It is shown that the inclusion of junctions characterized by non-sinusoidal current - phase relationship in the systems composed of multiple Josephson junctions - results in the appearance of additional system phase states. Numerical simulations and stability considerations confirm that those phase states can be realized in practice. Moreover, spontaneous formation of the grain boundary junctions in high-T c superconductors with non-trivial current-phase relations due to the d-wave symmetry of the order parameter is probable. Switching between the phase states of multiple grain boundary junction systems can lead to additional 1/f noise in high-T c superconductors. (author)

Implications of ITER requirements on R and D of RF heating and current drive systems

International Nuclear Information System (INIS)

Bosia, G.

2002-01-01

A strategic, rather than auxiliary role is assigned to H and CD systems in ITER-FEAT, as all operation phases are driven and controlled by heating and current drive (H and CD) systems. RF systems (Electron Cyclotron, Ion Cyclotron and Lower Hybrid), planned to contribute for ∼60% of ITER auxiliary power (72 MW), still require different level of pre-industrial technology development to operate in ITER at the required level of efficiency and religiosite. In this paper, RF H and CD systems technical and operational issues are reviewed and future R and D actions at CEA-Cadarache discussed, with the aim of providing a demonstration of all RF H and CD systems, within the current ITER construction time scale. The need and the economical advantage of an early on- and off- plasma design validation program for ITER-like RF devices (such as launcher and/or power sources), is also discussed with the aim of identifying and resolving operational issues. (author)

Unfolded equations for current interactions of 4d massless fields as a free system in mixed dimensions

Energy Technology Data Exchange (ETDEWEB)

Gelfond, O. A., E-mail: gel@lpi.ru [Russian Academy of Sciences, Institute of System Research (Russian Federation); Vasiliev, M. A., E-mail: vasiliev@lpi.ru [Russian Academy of Sciences, I. E. Tamm Department of Theoretical Physics, Lebedev Physical Institute (Russian Federation)

2015-03-15

Interactions of massless fields of all spins in four dimensions with currents of any spin are shown to result from a solution of the linear problem that describes a gluing between a rank-one (massless) system and a rank-two (current) system in the unfolded dynamics approach. Since the rank-two system is dual to a free rank-one higher-dimensional system that effectively describes conformal fields in six space-time dimensions, the constructed system can be interpreted as describing a mixture between linear conformal fields in four and six dimensions. An interpretation of the obtained results in the spirit of the AdS/CFT correspondence is discussed.

Adaptive Hysteresis Band Current Control (AHB) with PLL of Grid Side Converter-Based Wind Power Generation System

DEFF Research Database (Denmark)

Guo, Yougui; Zeng, Ping; Li, Lijuan

2011-01-01

Adaptive hysteresis band current control(AHB CC) is used to control the three-phase grid currents by means of grid side converter in wind power generation system in this paper. AHB has reached the good purpose with PLL (Lock phase loop). First the mathematical models of each part are given......, transformer and grid, and control parts, etc. The simulation results have verified that the control strategy is feasible to fit for control of gird currents, active power, reactive power and DC-link voltage in wind power generation system....

Review on the current trends in tongue diagnosis systems.

Science.gov (United States)

Jung, Chang Jin; Jeon, Young Ju; Kim, Jong Yeol; Kim, Keun Ho

2012-12-01

Tongue diagnosis is an essential process to noninvasively assess the condition of a patient's internal organs in traditional medicine. To obtain quantitative and objective diagnostic results, image acquisition and analysis devices called tongue diagnosis systems (TDSs) are required. These systems consist of hardware including cameras, light sources, and a ColorChecker, and software for color correction, segmentation of tongue region, and tongue classification. To improve the performance of TDSs, various types TDSs have been developed. Hyperspectral imaging TDSs have been suggested to acquire more information than a two-dimensional (2D) image with visible light waves, as it allows collection of data from multiple bands. Three-dimensional (3D) imaging TDSs have been suggested to provide 3D geometry. In the near future, mobile devices like the smart phone will offer applications for assessment of health condition using tongue images. Various technologies for the TDS have respective unique advantages and specificities according to the application and diagnostic environment, but this variation may cause inconsistent diagnoses in practical clinical applications. In this manuscript, we reviewed the current trends in TDSs for the standardization of systems. In conclusion, the standardization of TDSs can supply the general public and oriental medical doctors with convenient, prompt, and accurate information with diagnostic results for assessing the health condition.

A study on the national safeguards system -Current status and suggested development-

International Nuclear Information System (INIS)

Park, Wan Su; Kwack, Eun Ho; An, Jong Sung; Kim, Hyun Tae; Min, Kyung Sik; Park, Chan Sik

1995-03-01

In Korea, 17 nuclear facilities are currently under IAEA's safeguards and it is expected that more than 25 nuclear facilities will be under IAEA's safeguards in the year 2000 according to nuclear R and D and industry expansion. In connection with unlimited extension of NPT in 1995 and IAEA's measures to strengthen the safeguards like 'Programme 93+2', the international non-proliferation regime will be strengthened more and nuclear advanced countries will require the transparency and credibility of nuclear activities in recipient countries instead of transferring advanced nuclear technologies and nuclear material. In 1995, the Korean government had revised the Atomic Energy Law to control increasing nuclear facilities and nuclear material effectively and to establish international transparency and credibility. In the revised Atomic Energy Law, it is provided that the national inspection, other than IAEA inspection, will be started from 1996. Currently, necessary arrangements for national inspection are being prepared by MOST and TCNC at KAERI. However, the safeguards system in Korea is still beginning stage, Korea's safeguards activity was passive and fragmentary that leads non-attainment of safeguards goal in many facilities. The reasons were; absence of systematic safeguards system (SSAC); lack of understanding safeguards concepts; lack of manpower, designated organization for safeguards, etc. As Korea ranked world top 10 nuclear power generation country and has a plan to be a nuclear advanced country, Korea should have appropriate safeguards system and should not spare necessary assistance to that system. 14 tabs., 15 figs., 29 refs. (Author)

Enhanced Phase-Shifted Current Control for Harmonic Cancellation in Three-Phase Multiple Adjustable Speed Drive Systems

DEFF Research Database (Denmark)

Yang, Yongheng; Davari, Pooya; Zare, Firuz

2017-01-01

A phase-shifted current control can be employed to mitigate certain harmonics induced by the Diode Rectifiers (DR) and Silicon-Controlled Rectifiers (SCR) as the front-ends of multiple parallel Adjustable Speed Drive (ASD) systems. However, the effectiveness of the phase-shifted control relies...... on the loading condition of each drive unit as well as the number of drives in parallel. In order to enhance the harmonic cancellation by means of the phase-shifted current control, the currents drawn by the rectifiers should be maintained almost at the same level. Thus, this paper firstly analyzes the impact...... of unequal loading among the parallel drives, and a scheme to enhance the performance is introduced to improve the quality of the total grid current, where partial loading operation should be enabled. Simulation and experimental case studies on multidrive systems have demonstrated that the enhanced phase...

SIMULATION OF FREE CURRENT FLOWS IN BUOYANCY-DRIVEN VENTILATION SYSTEMS

Directory of Open Access Journals (Sweden)

D. V. Abramkina

2017-01-01

Full Text Available Objectives. The aim of the study is to analyse the effect of the design and methods for heating the ventilation duct of a buoyancy- driven system on the formation of free convective air currents in it.Methods. The study of free convection under the conditions of interior problem was carried out using the CFD software, based on  the finite volume method with unstructured grid. Ansys Fluent software was used as a calculation tool in the study, due to its having a high convergence of numerical solutions offering full-scale  measurements of convective currents.To evaluate the reliability of  the results obtained, a validation procedure was carried out, allowing us to determine how accurately the selected conceptual model describes the investigated flow through a comparison of experimental and numerical data.Results. The results of numerical modelling of free convective currents occurring in the heated channel of the ventilation system of  the top floor of a multi-storey residential building are presented in  the article. In the course of the study, the air velocity at the entrance to the ventilation duct was found to depend on the calculated  temperature difference θ ˚C for various heating methods. A gradual  increase in the discrepancy between the numerical simulation and  experimental results is observed if the calculated temperature  difference > 20 ° C. This phenomenon is due to the fact that with  increased duct temperature, it is quite difficult to achieve even  heating under actual conditions; this is especially noticeable when  considering the variant when the vertical part of the vent duct and the take-off are both heated. The maximum deviation of the  results is 4.4%. The obtained velocity profiles in the calculated  sections indicate the impact of the ventilation take-off on the nature  of the air flow motion.Conclusion. One of the drawbacks of the existing systems of natural ventilation of residential

Optimization of a Two Stage Pulse Tube Refrigerator for the Integrated Current Lead System

Science.gov (United States)

Maekawa, R.; Matsubara, Y.; Okada, A.; Takami, S.; Konno, M.; Tomioka, A.; Imayoshi, T.; Hayashi, H.; Mito, T.

2008-03-01

Implementation of a conventional current lead with a pulse tube refrigerator has been validated to be working as an Integrated Current Lead (ICL) system for the Superconducting Magnetic Energy Storage (SMES). Realization of the system is primarily accounted for the flexibility of a pulse tube refrigerator, which does not posses any mechanical piston and/or displacer. As for an ultimate version of the ICL system, a High Temperature Superconducting (HTS) lead links a superconducting coil with a conventional copper lead. To ensure the minimization of heat loads to the superconducting coil, a pulse tube refrigerator has been upgraded to have a second cooling stage. This arrangement reduces not only the heat loads to the superconducting coil but also the operating cost for a SMES system. A prototype two-stage pulse tube refrigerator, series connected arrangement, was designed and fabricated to satisfy the requirements for the ICL system. Operation of the first stage refrigerator is a four-valve mode, while the second stage utilizes a double inlet configuration to ensure its confined geometry. The paper discusses the optimization of second stage cooling to validate the conceptual design

Development of an on-site calibration method for a current transformer testing system and its application

International Nuclear Information System (INIS)

Jung, Jae Kap; Lee, Sang Hwa; Kwon, Sung Won; Park, Young Tae

2008-01-01

The ratio error and phase displacement of a current transformer (CT) are measured by using a CT testing system, which consists of a current source, a standard CT, a CT under test, a CT comparator and a CT burden. Methods for on-site calibration of the components in CT testing systems in industry have been developed recently, which do not require any component to be detached from the systems. The method utilizes several travelling transfer standards: standard CTs, non-reactive standard resistors, a calculable wide-ratio error CT and non-reactive shunt resistors. The travelling standard CT is used for absolute evaluation of a current source and a standard CT of industry. The non-reactive standard resistors and the calculable wide-ratio error CT are used to evaluate the linearity of the errors in the CT comparator. The shunt resistors are used to evaluate the CT burden of industry. The on-site calibration method using these travelling transfer standards has been successfully applied to calibration of CT testing systems in industries

An “Off-the-Shelf” System for Intraprocedural Electrical Current Evaluation and Monitoring of Irreversible Electroporation Therapy

Energy Technology Data Exchange (ETDEWEB)

Neal, Robert E., E-mail: Robert.Neal@alfred.org.au; Kavnoudias, Helen; Thomson, Kenneth R. [The Alfred Hospital, Radiology Research Unit, Department of Radiology (Australia)

2015-06-15

IntroductionIrreversible electroporation (IRE) ablation uses a series of brief electric pulses to create nanoscale defects in cell membranes, killing the cells. It has shown promise in numerous soft-tissue tumor applications. Larger voltages between electrodes will increase ablation volume, but exceeding electrical limits may risk damage to the patient, cause ineffective therapy delivery, or require generator restart. Monitoring electrical current for these conditions in real-time enables managing these risks. This capacity is not presently available in clinical IRE generators.MethodsWe describe a system using a Tektronix TCP305 AC/DC Current Probe connected to a TCPA300 AC/DC Current Probe Amplifier, which is read on a computer using a Protek DSO-2090 USB computer-interfacing oscilloscope. Accuracy of the system was tested with a resistor circuit and by comparing measured currents with final outputs from the NanoKnife clinical electroporation pulse generator.ResultsAccuracy of measured currents was 1.64 ± 2.4 % relative to calculations for the resistor circuit and averaged 0.371 ± 0.977 % deviation from the NanoKnife. During clinical pulse delivery, the system offers real-time evaluation of IRE procedure progress and enables a number of methods for identifying approaching issues from electrical behavior of therapy delivery, facilitating protocol changes before encountering therapy delivery issues.ConclusionsThis system can monitor electrical currents in real-time without altering the electric pulses or modifying the pulse generator. This facilitates delivering electric pulse protocols that remain within the optimal range of electrical currents—sufficient strength for clinically relevant ablation volumes, without the risk of exceeding safe electric currents or causing inadequate ablation.

Space Vector Modulation Technique to Reduce Leakage Current of a Transformerless Three-Phase Four-Leg Photovoltaic System

Directory of Open Access Journals (Sweden)

F. Hasanzad

2017-06-01

Full Text Available Photovoltaic systems integrated to the grid have received considerable attention around the world. They can be connected to the electrical grid via galvanic isolation (transformer or without it (transformerless. Despite making galvanic isolation, low frequency transformer increases size, cost and losses. On the other hand, transformerless PV systems increase the leakage current (common-mode current, (CMC through the parasitic capacitors of the PV array. Inverter topology and switching technique are the most important parameters the leakage current depends on. As there is no need to extra hardware for switching scheme modification, it's an economical method for reducing leakage current. This paper evaluates the effect of different space vector modulation techniques on leakage current for a two-level three-phase four-leg inverter used in PV system. It proposes an efficient space vector modulation method which decreases the leakage current to below the quantity specified in VDE-0126-1-1 standard. furthermore, some other characteristics of the space vector modulation schemes that have not been significantly discussed for four-leg inverter, are considered, such as, modulation index, switching actions per period, common-mode voltage (CMV, and total harmonic distortion (THD. An extend software simulation using MATLAB/Simulink is performed to verify the effectiveness of the modulation technique.

A hybrid superconducting fault current limiter for enhancing transient stability in Korean power systems

Science.gov (United States)

Seo, Sangsoo; Kim, Seog-Joo; Moon, Young-Hwan; Lee, Byongjun

2013-11-01

Additional power generation sites have been limited in Korea, despite the fact load demands are gradually increasing. In order to meet these increasing demands, Korea’s power system company has begun constructing new generators at existing sites. Thus, multi-unit plants can create problems in terms of transient stability when a large disturbance occurs. This paper proposes a hybrid superconducting fault current limiter (SFCL) application to enhance the transient stability of multi-unit power plants. SFCLs reduce fault currents, and limitation currents decrease the imbalance of the mechanical and electrical torque of the generators, resulting in an improvement in transient stability.

A Power Supply System with ZVS and Current-Doubler Features for Hybrid Renewable Energy Conversion

Directory of Open Access Journals (Sweden)

Jye-Chau Su

2013-09-01

Full Text Available In this paper, a power supply system for hybrid renewable energy conversion is proposed, which can process PV (photovoltaic power and wind-turbine energy simultaneously for step-down voltage and high current applications. It is a dual-input converter and mainly contains a PV energy source, a wind turbine energy source, a zero-voltage-switching (ZVS forward converter, and a current-doubler rectifier. The proposed power supply system has the following advantages: (1 PV-arrays and wind-energy sources can alternatively deliver power to the load during climate or season alteration; (2 maximum power point tracking (MPPT can be accomplished for both different kinds of renewable-energy sources; (3 ZVS and synchronous rectification techniques for the active switches of the forward converter are embedded so as to reduce switching and conducting losses; and (4 electricity isolation is naturally obtained. To achieve an optimally dynamic response and to increase control flexibility, a digital signal processor (DSP is investigated and presented to implement MPPT algorithm and power regulating scheme. Finally, a 240 W prototype power supply system with ZVS and current-doubler features to deal with PV power and wind energy is built and implemented. Experimental results are presented to verify the performance and the feasibility of the proposed power supply system.

Automation of eddy current system for in-service inspection of turbine and generator rotor bores

International Nuclear Information System (INIS)

Anon.

1987-01-01

The current project (EPRI-RP-1975-5) is a continuation of activities that began several years ago. Those results (EPRI-RP-1957-1) indicated that eddy current testing shows promise for in-service inspection. The current project investigates the degree to which eddy current testing can be used to replace bore magnetic particle testing. For this purpose, correlation studies between eddy current and magnetic particle tests are being undertaken on laboratory rotor sections and field test pieces of rotors. The eddy current data are to be gathered automatically by a combination of the Nortec-25L Eddyscope (to provide the analog eddy current signals) and the General Electric DATAQ/sup TM/ (a registered trademark of the General Electric Co.) System (to perform the automatic data acquisition). This paper describes some test results on a flaked laboratory rotor section

Data-based Modeling of the Dynamical Inner Magnetosphere During Strong Geomagnetic Storms

Science.gov (United States)

Tsyganenko, N.; Sitnov, M.

2004-12-01

This work builds on and extends our previous effort [Tsyganenko et al., 2003] to develop a dynamical model of the storm-time geomagnetic field in the inner magnetosphere, using space magnetometer data taken during 37 major events in 1996--2000 and concurrent observations of the solar wind and IMF. The essence of the approach is to derive from the data the temporal variation of all major current systems contributing to the geomagnetic field during the entire storm cycle, using a simple model of their growth and decay. Each principal source of the external magnetic field (magnetopause, cross-tail current sheet, axisymmetric and partial ring currents, Birkeland currents) is controlled by a separate driving variable that includes a combination of geoeffective parameters in the form Nλ Vβ Bsγ , where N, V, and Bs are the solar wind density, speed, and the magnitude of the southward component of the IMF, respectively. Each source was also assumed to have an individual relaxation timescale and residual quiet-time strength, so that its partial contribution to the total field was calculated for any moment as a time integral, taking into account the entire history of the external driving of the magnetosphere during each storm. In addition, the magnitudes of the principal field sources were assumed to saturate during extremely large storms with abnormally strong external driving. All the parameters of the model field sources, including their magnitudes, geometrical characteristics, solar wind/IMF driving functions, decay timescales, and saturation thresholds were treated as free variables, to be derived from the data by the least squares. The relaxation timescales of the individual magnetospheric field sources were found to largely differ between each other, from as large as ˜30 hours for the symmetrical ring current to only ˜50 min for the region~1 Birkeland current. The total magnitudes of the currents were also found to dramatically vary in the course of major storms

'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.

Physical Limitations of Empirical Field Models: Force Balance and Plasma Pressure

International Nuclear Information System (INIS)

Sorin Zaharia; Cheng, C.Z.

2002-01-01

In this paper, we study whether the magnetic field of the T96 empirical model can be in force balance with an isotropic plasma pressure distribution. Using the field of T96, we obtain values for the pressure P by solving a Poisson-type equation (gradient) 2 P = (gradient) · (J x B) in the equatorial plane, and 1-D profiles on the Sun-Earth axis by integrating (gradient)P = J x B. We work in a flux coordinate system in which the magnetic field is expressed in terms of Euler potentials. Our results lead to the conclusion that the T96 model field cannot be in equilibrium with an isotropic pressure. We also analyze in detail the computation of Birkeland currents using the Vasyliunas relation and the T96 field, which yields unphysical results, again indicating the lack of force balance in the empirical model. The underlying reason for the force imbalance is likely the fact that the derivatives of the least-square fitted model B are not accurate predictions of the actual magnetospheric field derivatives. Finally, we discuss a possible solution to the problem of lack of force balance in empirical field models

Current-potential characteristics of electrochemical systems

Energy Technology Data Exchange (ETDEWEB)

Battaglia, Vincent S. [Univ. of California, Berkeley, CA (United States)

1993-07-01

This dissertation contains investigations in three distinct areas. Chapters 1 and 2 provide an analysis of the effects of electromagnetic phenomena during the initial stages of cell discharge. Chapter 1 includes the solution to Maxwell`s equations for the penetration of the axial component of an electric field into an infinitely long cylindrical conductor. Chapter 2 contains the analysis of the conductor included in a radial circuit. Chapter 3 provides a complete description of the equations that describe the growth of an oxide film. A finite difference program was written to solve the equations. The system investigated is the iron/iron oxide in a basic, aqueous solution. Chapters 4 and 5 include the experimental attempts for replacing formaldehyde with an innocuous reducing agent for electroless deposition. In chapter 4, current-versus-voltage curves are provided for a sodium thiosulfate bath in the presence of a copper disk electrode. Also provided are the cathodic polarization curves of a copper/EDTA bath in the presence of a copper electrode. Chapter 5 contains the experimental results of work done with sodium hypophosphite as a reducing agent. Mixed-potential-versus-time curves for solutions containing various combinations of copper sulfate, nickel chloride, and hypophosphite in the presence of a palladium disk electrode provide an indication of the reducing power of the solutions.

Evaluation of advanced and current leak detection systems

International Nuclear Information System (INIS)

Kupperman, D.S.

1988-01-01

U.S. Nuclear Regulatory Commission Guide 1.45 recommends the use of at least three different detection methods in reactors to detect leakage. Monitoring of both sump-flow and airborne particulate radioactivity is mandatory. A third method can involve either monitoring of condensate flow rate from air coolers or monitoring of airborne gaseous radioactivity. Although the methods currently used for leak detection reflect the state of the art, other techniques may be developed and used. Since the recommendations of Regulatory Guide 1.45 are not mandatory, Licensee Event Report Compilations have been reviewed to help establish actual capabilities for leak detection. The review of event reports, which had previously covered the period of June 1985 to August 1986 has been extended, and now covers events to June 1987. The total number of significant events is now 83. These reports have provided documented, sometimes detailed, summaries of reactor leaks. They have helped establish the capabilities of existing systems to detect and locate leaks. Differences between PWRs and BWRs with regard to leak detection have now been analyzed. With regard to detection methods, the greatest differences between reactor types are as follows: (a) The sump pump is reported as the detection method more frequently in BWRs than in PWRs (64% vs. 35%). (b) The radiation monitor is reported as the detection method (excluding false alarms) more frequently in PWRs. Current efforts at Argonne National Laboratory (ANL) to evaluate advanced acoustic leak detection methods are directed toward the generation and analysis of acoustic data from large (0.5 to 10 gal/min) leaks and modification of the software of the GARD/ANL advanced acoustic leak detection system. In order to reach the goal of 10 gal/min leaks, the Steam Generator Test Facility at ANL has been modified to carry out the leak testing. Tests were carried out with water at 525 deg. F and 1100 psi leaking through a fatigue crack in a 4-in

The Early Awareness and Alert System in Sweden: History and Current Status

Directory of Open Access Journals (Sweden)

Irene Eriksson

2017-10-01

Full Text Available Introduction: Over the past decades, early awareness and alert (EAA activities and systems have gained importance and become a key early health technology assessment (HTA tool. While a pioneer in HTA, Sweden had no national level EAA activities until 2010. We describe the evolution and current status of the Swedish EAA System.Methods: This was a historical analysis based on the knowledge and experience of the authors supplemented by a targeted review of published and gray literature as well as documents relating to EAA activities in Sweden. Key milestones and a description of the current state of the Swedish EAA System is presented.Results: Initiatives to establish a system for the identification and assessment of emerging health technologies in Sweden date back to the 1980s. In the 1990s, the Swedish Agency for HTA and Assessment of Social Services (SBU supported the development of EuroScan as one of its founder members. In the mid-2000s, an independent regional initiative, driven by the Stockholm County Drug and Therapeutics Committee, resulted in the establishment of a regional horizon scanning function. By 2009, this work had expanded to a collaboration between the four biggest counties in Sweden. The following year it was further expanded to the national level and since then the Swedish EAA System has been carrying out identification, filtration and prioritization of new medicines, early assessment of the prioritized medicines, and dissemination of information. In 2015, the EAA System was incorporated into the Swedish national process for managed introduction and follow-up of new medicines. Outputs from the EAA System are now used to select new medicines for inclusion in this process.Conclusions: The Swedish EAA System started as a regional initiative and rapidly grew to become a national level activity. An important feature of the system today is its complete integration into the national process for managed introduction and follow-up of

Real time Aanderaa current meter data collection system

Digital Repository Service at National Institute of Oceanography (India)

AshokKumar, K.; Diwan, S.G.

Aanderaa current meters are widely used for recording the current speed and such other 4 parameters by deploying them over extended period of time. Normally data are recorded on magnetic tape and after recovery of current meters, data are read...

Oscillation and decay of particle current due to a quench and dephasing in an interacting fermionic system

OpenAIRE

Choo, Kenny; Bissbort, Ulf; Poletti, Dario

2017-01-01

We study the response of a particle current to dissipative dephasing in an interacting, few-body fermionic lattice system. The particles are prepared in the ground state in presence of an artificial magnetic gauge field, which is subsequently quenched to zero. The initial current decays non-trivially in the dissipative environment and we explore the emerging dynamics and its dependence on various system parameters.

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.

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

International Nuclear Information System (INIS)

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

2016-01-01

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.

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.

Fault Ride Through Capability Enhancement of a Large-Scale PMSG Wind System with Bridge Type Fault Current Limiters

Directory of Open Access Journals (Sweden)

ALAM, M. S.

2018-02-01

Full Text Available In this paper, bridge type fault current limiter (BFCL is proposed as a potential solution to the fault problems of permanent magnet synchronous generator (PMSG based large-scale wind energy system. As PMSG wind system is more vulnerable to disturbances, it is essential to guarantee the stability during severe disturbances by enhancing the fault ride through capability. BFCL controller has been designed to insert resistance and inductance during the inception of system disturbances in order to limit fault current. Constant capacitor voltage has been maintained by the grid voltage source converter (GVSC controller while current extraction or injection has been achieved by machine VSC (MVSC controller. Symmetrical and unsymmetrical faults have been applied in the system to show the effectiveness of the proposed BFCL solution. PMSG wind system, BFCL and their controllers have been implemented by real time hardware in loop (RTHIL setup with real time digital simulator (RTDS and dSPACE. Another significant feature of this work is that the performance of the proposed BFCL is compared with that of series dynamic braking resistor (SDBR. Comparative RTHIL implementation results show that the proposed BFCL is very efficient in improving system fault ride through capability by limiting the fault current and outperforms SDBR.

Control systems for ITER diagnostics, heating and current drive

Energy Technology Data Exchange (ETDEWEB)

Simrock, Stefan, E-mail: stefan.simrock@iter.org

2016-11-15

The ITER Diagnostic, Heating and Current Drive systems might appear, on the face of it, to have very different control requirements. There are approximately 45 diagnostic systems, including magnetic sensors for plasma position and shape determination, imaging systems in the IR and visible, Thompson scattering for electron temperature and density, neutron detectors and collective scattering for alpha particle density and energy distribution. The H&CD systems encompass Electron Cyclotron Heating, using 24 1MW, 170 GHz gyrotrons and 5 steerable launchers to deliver 20 MW to the plasma, Ion Cyclotron Heating, using 8 3MW, 40–55 MHz sources and two multi-element launchers to deliver 20 MW to the plasma, and 2 Negative Ion Neutral Beam Injectors, each of which can deliver up to 16.5 MW of 1 MeV beams to the plasma. Although there are substantial differences in the needs for protection, when handling multi-MW heating systems, and in data throughput for many diagnostics, the formal processes needed to translate system requirements into Instrumentation and Control are identical. Due to the distributed procurement of ITER sub-systems and the need to integrate as painlessly as possible to CODAC, the formal processes, together with a substantial degree of standardization, are even more than usually essential. Starting from the technical, safety and protection, integration and operation requirements, a loop of functional analysis and signal listing is used to generate the controller configuration and the conceptual architecture. These elements in their turn lead to the physical and software design. The paper will describe the formal processes of control system design and the methods used by the ITER project to achieve the standardization of systems engineering practices. These have been applied to several use-cases covering all operation relevant phases such as plasma operation, maintenance, testing and conditioning. There are a number of running contracts that are developing

DC Link Current Estimation in Wind-Double Feed Induction Generator Power Conditioning System

Directory of Open Access Journals (Sweden)

MARIAN GAICEANU

2010-12-01

Full Text Available In this paper the implementation of the DC link current estimator in power conditioning system of the variable speed wind turbine is shown. The wind turbine is connected to double feed induction generator (DFIG. The variable electrical energy parameters delivered by DFIG are fitted with the electrical grid parameters through back-to-back power converter. The bidirectional AC-AC power converter covers a wide speed range from subsynchronous to supersynchronous speeds. The modern control of back-to-back power converter involves power balance concept, therefore its load power should be known in any instant. By using the power balance control, the DC link voltage variation at the load changes can be reduced. In this paper the load power is estimated from the dc link, indirectly, through a second order DC link current estimator. The load current estimator is based on the DC link voltage and on the dc link input current of the rotor side converter. This method presents certain advantages instead of using measured method, which requires a low pass filter: no time delay, the feedforward current component has no ripple, no additional hardware, and more fast control response. Through the numerical simulation the performances of the proposed DC link output current estimator scheme are demonstrated.

Review on the current trends in tongue diagnosis systems

Directory of Open Access Journals (Sweden)

Chang Jin Jung

2012-12-01

Full Text Available Tongue diagnosis is an essential process to noninvasively assess the condition of a patient's internal organs in traditional medicine. To obtain quantitative and objective diagnostic results, image acquisition and analysis devices called tongue diagnosis systems (TDSs are required. These systems consist of hardware including cameras, light sources, and a ColorChecker, and software for color correction, segmentation of tongue region, and tongue classification. To improve the performance of TDSs, various types TDSs have been developed. Hyperspectral imaging TDSs have been suggested to acquire more information than a two-dimensional (2D image with visible light waves, as it allows collection of data from multiple bands. Three-dimensional (3D imaging TDSs have been suggested to provide 3D geometry. In the near future, mobile devices like the smart phone will offer applications for assessment of health condition using tongue images. Various technologies for the TDS have respective unique advantages and specificities according to the application and diagnostic environment, but this variation may cause inconsistent diagnoses in practical clinical applications. In this manuscript, we reviewed the current trends in TDSs for the standardization of systems. In conclusion, the standardization of TDSs can supply the general public and oriental medical doctors with convenient, prompt, and accurate information with diagnostic results for assessing the health condition.

Current state in the research on electronic monitoring systems for the security and flow of objects and individuals

Directory of Open Access Journals (Sweden)

Man Dietrich Marcela

2017-01-01

Full Text Available This paper sets forth the current state of security systems in prisons from Romania and around the world, particularly aiming electronic systems of monitoring the flow of people, materials control and perimeter security, focusing on the research results concluded by motion detection tests and devices. The currently used systems were observed in order to put an analysis of the methodology together and implement and perfect these systems in protected areas. The protection of citizens must be performed to the extent that is allowed by the legislation.

Cryogenic current leads

Energy Technology Data Exchange (ETDEWEB)

Zizek, F.

1982-01-01

Theoretical, technical and design questions are examined of cryogenic current leads for SP of magnetic systems. Simplified mathematical models are presented for the current leads. To illustrate modeling, the calculation is made of the real current leads for 500 A and three variants of current leads for 1500 A for the enterprise ''Shkoda.''

Current approach for urinary system stone disease in pregnant women

Directory of Open Access Journals (Sweden)

Orcun Celik

2016-01-01

Full Text Available Urinary system stones can be classified according to size, location, X-ray characteristics, aetiology of formation, composition, and risk of recurrence. Especially urolithiasis during pregnancy is a diagnostic and therapeutic challenge. In most cases, it becomes symptomatic in the second or third trimester. Diagnostic options in pregnant women are limited due to the possible teratogenic, carcinogenic, and mutagenic risk of foetal radiation exposure. Clinical management of a pregnant urolithiasis patient is complex and demands close collaboration between patient, obstetrician and urologist. We would like to review current diagnosis and treatment modalities of stone disease of pregnant woman.

A Discovery Process for Initializing Ad Hoc Underwater Acoustic Networks

Science.gov (United States)

2008-12-01

range1; // rules to filter 2 ranges if (range1 == 0 && range2 != 0) range = range2; if (range1 != 0 && range2 != 0...range2; if (range1 != 0 && range2 == 0) range = range1; // rules to filter 2 ranges if (range1 == 0 && range2 != 0...Birkeland Norwegian Defence Research Establishment (FFI) Horten, Norway 47. Ed Franchi Naval Research Laboratory Washington D.C. 48. RADM

MFA Graduate Show 2015: In the Usual Direction of Travel

OpenAIRE

2015-01-01

Avgangsstudenter: Patrik Berg, Christian Magnus Tømmeraas Berg, Maia Birkeland, Matilda Björkne, Stine Bråthen, Stein Are Kjærås Dahl, Emil Gustafsson, Jeanett Gustavsen, hÅkon gÅre, Jørgen Frederik Scheel Haarstad, Anita Hanch-Hansen, Elin Hedberg, Andrea Wikhammer Heir, Steinar Laumann, Aron-Irving Li, Tina Lindvall, Rebecca Szabo Onstad, Zahra Rashid, Hege Cathrine Hauge Thoresen

Weak Thermocline Mixing in the North Pacific Low-Latitude Western Boundary Current System

Science.gov (United States)

Liu, Zhiyu; Lian, Qiang; Zhang, Fangtao; Wang, Lei; Li, Mingming; Bai, Xiaolin; Wang, Jianing; Wang, Fan

2017-10-01

Despite its potential importance in the global climate system, mixing properties of the North Pacific low-latitude western boundary current system (LLWBC) remained unsampled until very recently. We report here on the first measurements of turbulence microstructure associated with these currents, made in the western boundary region of the tropical North Pacific east of the Philippines. The results suggest that thermocline mixing in the North Pacific LLWBC is generally weak with the diapycnal diffusivity κρ˜O(10-6) m2 s-1. This is consistent with predictions from internal wave-wave interaction theory that mixing due to internal wave breaking is significantly reduced at low latitudes. Enhanced mixing is found to be associated with a permanent cyclonic eddy, the Mindanao Eddy, but mainly at its south and north flanks. There, κρ is elevated by an order of magnitude due to eddy-induced geostrophic shear. Mixing in the eddy core is at the background level with no indication of enhancement.

Robust low frequency current ripple elimination algorithm for grid-connected fuel cell systems with power balancing technique

Energy Technology Data Exchange (ETDEWEB)

Kim, Jong-Soo; Choe, Gyu-Yeong; Lee, Byoung-Kuk [School of Information and Communication Engineering, Sungkyunkwan University, 300 Cheoncheon-dong, Jangan-gu, Suwon, Gyeonggi-do 440-746 (Korea, Republic of); Kang, Hyun-Soo [R and D Center, Advanced Drive Technology (ADT) Company, 689-26 Geumjeong-dong, Gunpo-si, Gyeonggi-do 435-862 (Korea, Republic of)

2011-05-15

The low frequency current ripple in grid-connected fuel cell systems is generated from dc-ac inverter operation, which generates 60 Hz fundamental component, and gives harmful effects on fuel cell stack itself, such as making cathode surface responses slower, causing an increase of more than 10% in the fuel consumption, creating oxygen starvation, causing a reduction in the operating lifetime, and incurring a nuisance tripping such as overload situation. With these reasons, low frequency current ripple makes fuel cell system unstable and lifetime of fuel cell stack itself short. This paper presents a fast and robust control algorithm to eliminate low frequency current ripple in grid-connected fuel cell systems. Compared with the conventional methods, in the proposed control algorithm, dc link voltage controller is shifted from dc-dc converter to dc-ac inverter, resulting that dc-ac inverter handles dc link voltage control and output current control simultaneously with help of power balancing technique. The results indicate that the proposed algorithm can not only completely eliminate current ripple but also significantly reduce the overshoot or undershoot during transient states without any extra hardware. The validity of the proposed algorithm is verified by computer simulations and also by experiments with a 1 kW laboratory prototype. (author)

Alternatives for blocking direct current in AC system neutrals at the Radisson/LG2 complex

International Nuclear Information System (INIS)

Eitzmann, M.A.; Walling, R.A.; Sublich, M.; Kah, A.; Huynh, H.; Granger, M.; Dutil, A.

1992-01-01

Severe offset saturation results from the passage of direct current through power transformers. Such direct current can arise from geomagnetic disturbances, or resistive coupling of the substation ground to HVDC earth electrodes. This paper documents the development of alternative approaches for the design and application of blocking devices placed between transformer neutrals and the substation ground. System constraints on the impedance and overvoltage limitation of the neutral blocking device (NBD) are covered. Three alternative NBD schemes are developed and optimized. System performance of the NBD is discussed, as are the practical implementation considerations for this unconventional equipment application. Although the paper focuses on the NBD requirements of Hydro-Quebec's Radisson/LG2 complex, the fundamental information is applicable to any situation where dc must be clocked from a power transformer neutral in a system designed for effectively-grounded operation

A distributed control system for the lower-hybrid current drive system on the Tokamak de Varennes

International Nuclear Information System (INIS)

Bagdoo, J.; Guay, J.M.; Chaudron, G.A.; Decoste, R.; Demers, Y.; Hubbard, A.

1990-01-01

An rf current drive system with an output power of 1 MW at 3.7 GHz is under development for the Tokamak de Varennes. The control system is based on an Ethernet local-area network of programmable logic controllers as front end, personal computers as consoles, and CAMAC-based DSP processors. The DSP processors ensure the PID control of the phase and rf power of each klystron, and the fast protection of high-power rf hardware, all within a 40 μs loop. Slower control and protection, event sequencing and the run-time database are provided by the programmable logic controllers, which communicate, via the LAN, with the consoles. The latter run a commercial process-control console software. The LAN protocol respects the first four layers of the ISO/OSI 802.3 standard. Synchronization with the tokamak control system is provided by commercially available CAMAC timing modules which trigger shot-related events and reference waveform generators. A detailed description of each subsystem and a performance evaluation of the system will be presented. (orig.)

A distributed control system for the lower-hybrid current drive system on the Tokamak de Varennes

Science.gov (United States)

Bagdoo, J.; Guay, J. M.; Chaudron, G.-A.; Decoste, R.; Demers, Y.; Hubbard, A.

1990-08-01

An rf current drive system with an output power of 1 MW at 3.7 GHz is under development for the Tokamak de Varennes. The control system is based on an Ethernet local-area network of programmable logic controllers as front end, personal computers as consoles, and CAMAC-based DSP processors. The DSP processors ensure the PID control of the phase and rf power of each klystron, and the fast protection of high-power rf hardware, all within a 40 μs loop. Slower control and protection, event sequencing and the run-time database are provided by the programmable logic controllers, which communicate, via the LAN, with the consoles. The latter run a commercial process-control console software. The LAN protocol respects the first four layers of the ISO/OSI 802.3 standard. Synchronization with the tokamak control system is provided by commercially available CAMAC timing modules which trigger shot-related events and reference waveform generators. A detailed description of each subsystem and a performance evaluation of the system will be presented.

Filtering and Control of High Speed Motor Current in a Flywheel Energy Storage System

Science.gov (United States)

Kenny, Barbara H.; Santiago, Walter

2004-01-01

The NASA Glenn Research Center has been developing technology to enable the use of high speed flywheel energy storage units in future spacecraft for the last several years. An integral part of the flywheel unit is the three phase motor/generator that is used to accelerate and decelerate the flywheel. The motor/generator voltage is supplied from a pulse width modulated (PWM) inverter operating from a fixed DC voltage supply. The motor current is regulated through a closed loop current control that commands the necessary voltage from the inverter to achieve the desired current. The current regulation loop is the innermost control loop of the overall flywheel system and, as a result, must be fast and accurate over the entire operating speed range (20,000 to 60,000 rpm) of the flywheel. The voltage applied to the motor is a high frequency PWM version of the DC bus voltage that results in the commanded fundamental value plus higher order harmonics. Most of the harmonic content is at the switching frequency and above. The higher order harmonics cause a rapid change in voltage to be applied to the motor that can result in large voltage stresses across the motor windings. In addition, the high frequency content in the motor causes sensor noise in the magnetic bearings that leads to disturbances for the bearing control. To alleviate these problems, a filter is used to present a more sinusoidal voltage to the motor/generator. However, the filter adds additional dynamics and phase lag to the motor system that can interfere with the performance of the current regulator. This paper will discuss the tuning methodology and results for the motor/generator current regulator and the impact of the filter on the control. Results at speeds up to 50,000 rpm are presented.

Removal of Direct Current Link Harmonic Ripple in Single Phase Voltage Source Inverter Systems Using Supercapacitors

Science.gov (United States)

2016-09-01

Khaligh, “Optimization of sizing and battery cycle life in battery/ultracapacitor hybrid energy storage systems for electric vehicle applications...depth cycling operation in photovoltaic system ,” in 22nd International Conference “Mixed Design of Integrated Circuits and Systems ,” Toruń, Poland...CURRENT LINK HARMONIC RIPPLE IN SINGLE-PHASE VOLTAGE SOURCE INVERTER SYSTEMS USING SUPERCAPACITORS by Gabriel D. Hernandez September 2016

Nutrient supply, surface currents, and plankton dynamics predict zooplankton hotspots in coastal upwelling systems

Science.gov (United States)

Messié, Monique; Chavez, Francisco P.

2017-09-01

A simple combination of wind-driven nutrient upwelling, surface currents, and plankton growth/grazing equations generates zooplankton patchiness and hotspots in coastal upwelling regions. Starting with an initial input of nitrate from coastal upwelling, growth and grazing equations evolve phytoplankton and zooplankton over time and space following surface currents. The model simulates the transition from coastal (large phytoplankton, e.g., diatoms) to offshore (picophytoplankton and microzooplankton) communities, and in between generates a large zooplankton maximum. The method was applied to four major upwelling systems (California, Peru, Northwest Africa, and Benguela) using latitudinal estimates of wind-driven nitrate supply and satellite-based surface currents. The resulting zooplankton simulations are patchy in nature; areas of high concentrations coincide with previously documented copepod and krill hotspots. The exercise highlights the importance of the upwelling process and surface currents in shaping plankton communities.

Simulating the hydrodynamic response of a floater–net system in current and waves

DEFF Research Database (Denmark)

Chen, Hao; Christensen, Erik Damgaard

2018-01-01

We present a novel numerical model for simulating current and wave interaction with a floater–net system. The main contribution of the paper is the integration of the floater motion and the fluid–structure interaction analysis of the net structure in the same modelling framework via the computati...

Characterizing volumetric discontinuities present in NPP heat exchangers with EASY: an eddy current data analysis system

Energy Technology Data Exchange (ETDEWEB)

Alencar, Donizete A.; Silva Junior, Silverio F., E-mail: daa@cdtn.b, E-mail: silvasf@cdtn.b [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil)

2011-07-01

Eddy current is a very important NDT inspection method widely used to perform integrity evaluation of tubes installed in heat exchangers. For nuclear power plants, a classical example is the remote inspection of steam generators and condensers, as well as other ordinary auxiliary equipment. Data evaluation can be performed by means of precise phase and amplitude measurements of complex impedance signals, represented as Lissajous figures plotted on the screen of the inspection systems. This paper presents the software EASY, a computer assisted analysis system developed at CDTN to help the characterization of volumetric discontinuities present in heat exchangers tubes. Data to be analyzed are obtained from commercial eddy current equipment data file, such as ECT MAD8D. Main advantage of that system is its portability and easy use, since it can be executed in ordinary PC, under Microsoft Windows operating system. (author)

Characterizing volumetric discontinuities present in NPP heat exchangers with EASY: an eddy current data analysis system

International Nuclear Information System (INIS)

Alencar, Donizete A.; Silva Junior, Silverio F.

2011-01-01

Eddy current is a very important NDT inspection method widely used to perform integrity evaluation of tubes installed in heat exchangers. For nuclear power plants, a classical example is the remote inspection of steam generators and condensers, as well as other ordinary auxiliary equipment. Data evaluation can be performed by means of precise phase and amplitude measurements of complex impedance signals, represented as Lissajous figures plotted on the screen of the inspection systems. This paper presents the software EASY, a computer assisted analysis system developed at CDTN to help the characterization of volumetric discontinuities present in heat exchangers tubes. Data to be analyzed are obtained from commercial eddy current equipment data file, such as ECT MAD8D. Main advantage of that system is its portability and easy use, since it can be executed in ordinary PC, under Microsoft Windows operating system. (author)

A Novel Method for the Current Harmonic Elimination of Industrial Power System Using Single Tuned Shunt Passive Filter

Directory of Open Access Journals (Sweden)

Mansoor Ahmed Soomro

2012-01-01

Full Text Available The automation of IPS (Industrial Power System has brought about several advantages of increased productivity and efficiency but it suffers from incompatible problems of overheating, noise, complexity etc, which disturb its smooth and fault tolerant implication. When the resonance condition is reached, these effects become detrimental and disturb the whole power system. The purpose of this research work is to include single tuned shunt type passive filter for harmonic elimination of the components used in industrial power system. For this purpose, MATLAB simulation using sim Power system tool has been used to analyze the effects of current harmonics. Third harmonic effects have been removed by the addition of six pulse converter technique. The simulation results show that implication of single tuned shunt (parallel connected passive filter removes effects of succeeding order current harmonics i.e. fifth, seventh and eleventh etc. which are causing substantial damage to industrial power system. The effects of current harmonics can be solved by installing without and with the application of proposed filter. Further, it is observed that these filters contribute in reduction of THD (Total Harmonic Current Distortion followed by improvement in power factor. These results are taken considering limits of IEEE 519-1992 standards.

An In-Rush Current Suppression Technique for the Solid-State Transfer Switch System

Science.gov (United States)

Cheng, Po-Tai; Chen, Yu-Hsing

More and more utility companies provide dual power feeders as a premier service of high power quality and reliability. To take advantage of this, the solid-state transfer switch (STS) is adopted to protect the sensitive load against the voltage sag. However, the fast transfer process may cause in-rush current on the load-side transformer due to the resulting DC-offset in its magnetic flux as the load-transfer is completed. The in-rush current can reach 2∼6 p.u. and it may trigger the over-current protections on the power feeder. This paper develops a flux estimation scheme and a thyristor gating scheme based on the impulse commutation bridge STS (ICBSTS) to minimize the DC-offset on the magnetic flux. By sensing the line voltages of both feeders, the flux estimator can predict the peak transient flux linkage at the moment of load-transfer and evaluate a suitable moment for the transfer to minimize the in-rush current. Laboratory test results are presented to validate the performance of the proposed system.

Octopamine increases the excitability of neurons in the snail feeding system by modulation of inward sodium current but not outward potassium currents

Directory of Open Access Journals (Sweden)

Szabó Henriette

2005-12-01

Full Text Available Abstract Background Although octopamine has long been known to have major roles as both transmitter and modulator in arthropods, it has only recently been shown to be functionally important in molluscs, playing a role as a neurotransmitter in the feeding network of the snail Lymnaea stagnalis. The synaptic potentials cannot explain all the effects of octopamine-containing neurons on the feeding network, and here we test the hypothesis that octopamine is also a neuromodulator. Results The excitability of the B1 and B4 motoneurons in the buccal ganglia to depolarising current clamp pulses is significantly (P IA current and a sustained IK delayed-rectifier current, but neither was modulated by octopamine in any of these three buccal neurons. The fast inward current was eliminated in sodium – free saline and so is likely to be carried by sodium ions. 10 μM octopamine enhanced this current by 33 and 45% in the B1 and B4 motoneurons respectively (P Conclusion We conclude that octopamine is also a neuromodulator in snails, changing the excitability of the buccal neurons. This is supported by the close relationship from the voltage clamp data, through the quantitative simulation, to the action potential threshold, changing the properties of neurons in a rhythmic network. The increase in inward sodium current provides an explanation for the polycyclic modulation of the feeding system by the octopamine-containing interneurons, making feeding easier to initiate and making the feeding bursts more intense.

Management of high current transients in the CWDD Injector 200 kV power system

International Nuclear Information System (INIS)

Carwardine, J.A.; Pile, G.; Zinneman, T.E.

1993-01-01

The injector for the Continuous Wave Deuterium Demonstrator is designed to deliver a high current CW negative deuterium ion beam at an energy of 200 keV to a Radio Frequency Quadrupole. The injector comprises a volume ion source, triode accelerator, high-power electron traps and low-energy beam transport with a single focusing solenoid. Some 75 Joules of energy are stored in stray capacitance around the high voltage system and discharged in a few microseconds following an injector breakdown. In order to limit damage to the accelerator grids, a magnetic snubber is incorporated to absorb most of the energy. Nevertheless, large current transients flow around the system as a result of an injector breakdown; these have frequently damaged power components and caused spurious behavior in many of the supporting systems. The analytical and practical approaches taken to minimize the effects of these transients are described. Injector breakdowns were simulated using an air spark gap and measurements made using standard EMC test techniques. The power circuit was modeled using an electrical simulation code; good agreement was reached between the model and measured results

Variable speed wind turbine generator system with current controlled voltage source inverter

International Nuclear Information System (INIS)

Muyeen, S.M.; Al-Durra, Ahmed; Tamura, J.

2011-01-01

highlights: → Current controlled voltage source inverter scheme for wind power application. → Low voltage ride through of wind farm. → Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

Variable speed wind turbine generator system with current controlled voltage source inverter

Energy Technology Data Exchange (ETDEWEB)

Muyeen, S.M., E-mail: muyeen0809@yahoo.co [Dept. of Electrical Engineering, Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Al-Durra, Ahmed [Dept. of Electrical Engineering, The Petroleum Institute, P.O. Box 2533, Abu Dhabi (United Arab Emirates); Tamura, J. [Dept. of EEE, Kitami Institute of Technology, 165 Koen-cho, Kitami 090-8507 (Japan)

2011-07-15

highlights: {yields} Current controlled voltage source inverter scheme for wind power application. {yields} Low voltage ride through of wind farm. {yields} Variable speed wind turbine driven permanent magnet synchronous generator-operation and control. -- Abstract: The present popular trend of wind power generation is to use variable speed wind turbine (VSWT) driving a doubly fed induction generator (DFIG), wound field synchronous generator (WFSG) or permanent magnet synchronous generator (PMSG). Among them, stability analyses of DFIG type of VSWT have already been reported in many literatures. However, transient stability and low voltage ride through (LVRT) characteristics analyses for synchronous generator type of VSWT is not sufficient enough. This paper focuses on detailed LVRT characteristic analysis of variable speed wind turbine driving a PMSG (VSWT-PMSG) with current controlled voltage source inverter (CC-VSI). Modeling and suitable control strategies for overall system are developed to augment the low voltage ride through capability of variable speed wind generator, considering recent wind farm grid code. Both symmetrical and unsymmetrical faults are analyzed as network disturbances in this paper. The permanent fault due to unsuccessful reclosing of circuit breakers is taken into consideration, which is a salient feature of this study. Moreover, the dynamic characteristic is analyzed using real wind speed data measured in Hokkaido Island, Japan. The proposed control scheme is simulated by using the standard power system simulation package PSCAD/EMTDC and results are verified by comparing that of voltage controlled voltage source inverter scheme available in power system literature.

Review of current status for designing severe accident management support system

Energy Technology Data Exchange (ETDEWEB)

Jeong, Kwang Sub

2000-05-01

The development of operator support system (OSS) is ongoing in many other countries due to the complexity both in design and in operation for nuclear power plant. The computerized operator support system includes monitoring of some critical parameters, early detection of plant transient, monitoring of component status, plant maintenance, and safety parameter display, and the operator support system for these areas are developed and are being used in some plants. Up to now, the most operator support system covers the normal operation, abnormal operation, and emergency operation. Recently, however, the operator support system for severe accident is to be developed in some countries. The study for the phenomena of severe accident is not performed sufficiently, but, based on the result up to now, the operator support system even for severe accident will be developed in this study. To do this, at first, the current status of the operator support system for normal/abnormal/emergency operation is reviewed, and the positive aspects and negative aspects of systems are analyzed by their characteristics. And also, the major items that should be considered in designing the severe accident operator support system are derived from the review. With the survey of domestic and foreign operator support systems, they are reviewed in terms of the safety parameter display system, decision-making support system, and procedure-tracking system. For the severe accident, the severe accident management guideline (SAMG) which is developed by Westinghouse is reviewed; the characteristics, structure, and logical flow of SAMG are studied. In addition, the critical parameters for severe accident, which are the basis for operators decision-making in severe accident management and are supplied to the operators and the technical support center, are reviewed, too.

Review of current status for designing severe accident management support system

International Nuclear Information System (INIS)

Jeong, Kwang Sub

2000-05-01

The development of operator support system (OSS) is ongoing in many other countries due to the complexity both in design and in operation for nuclear power plant. The computerized operator support system includes monitoring of some critical parameters, early detection of plant transient, monitoring of component status, plant maintenance, and safety parameter display, and the operator support system for these areas are developed and are being used in some plants. Up to now, the most operator support system covers the normal operation, abnormal operation, and emergency operation. Recently, however, the operator support system for severe accident is to be developed in some countries. The study for the phenomena of severe accident is not performed sufficiently, but, based on the result up to now, the operator support system even for severe accident will be developed in this study. To do this, at first, the current status of the operator support system for normal/abnormal/emergency operation is reviewed, and the positive aspects and negative aspects of systems are analyzed by their characteristics. And also, the major items that should be considered in designing the severe accident operator support system are derived from the review. With the survey of domestic and foreign operator support systems, they are reviewed in terms of the safety parameter display system, decision-making support system, and procedure-tracking system. For the severe accident, the severe accident management guideline (SAMG) which is developed by Westinghouse is reviewed; the characteristics, structure, and logical flow of SAMG are studied. In addition, the critical parameters for severe accident, which are the basis for operators decision-making in severe accident management and are supplied to the operators and the technical support center, are reviewed, too

Large-capacity current leads

International Nuclear Information System (INIS)

Ballarino, A.

2008-01-01

Feeding superconducting magnets with reliable low-loss devices is a key issue for any cryo-electrical system. Conventional or HTS current leads can be used, and cooling methods, materials, and geometries can be chosen to optimize the thermo-electrical performance of the system. The LHC magnets are powered via more than 3000 current leads transporting altogether about 3 MA of current. With thousands of leads, the LHC lead project represents today the largest project of its kind ever undertaken. Following a review of the LHC lead project, an overview of the choices that can be made for the optimization of large capacity current leads is presented. Examples are given of other leads for large scale magnet systems for which the use of HTS is being envisaged

Optimal coordination of distance and over-current relays in series compensated systems based on MAPSO

International Nuclear Information System (INIS)

Moravej, Zahra; Jazaeri, Mostafa; Gholamzadeh, Mehdi

2012-01-01

Highlight: ► Optimal coordination problem between distance relays and Directional Over-Current Relays (DOCRs) is studied. ► A new problem formulation for both uncompensated and series compensated system is proposed. ► In order to solve the coordination problem a Modified Adaptive Particle Swarm Optimization (MAPSO) is employed. ► The optimum results are found in both uncompensated and series compensated systems. - Abstract: In this paper, a novel problem formulation for optimal coordination between distance relays and Directional Over-Current Relays (DOCRs) in series compensated systems is proposed. The integration of the series capacitor (SC) into the transmission line makes the coordination problem more complex. The main contribution of this paper is a new systematic method for computing the optimal second zone timing of distance relays and optimal settings of DOCRs, in series compensated and uncompensated transmission systems, which have a combined protection scheme with DOCRs and distance relays. In order to solve this coordination problem, which is a nonlinear and non-convex problem, a Modified Adaptive Particle Swarm Optimization (MAPSO) is employed. The new proposed method is supported by obtained results from a typical test case and a real power system network.

Coliform Bacteria Monitoring in Fish Systems: Current Practices in Public Aquaria.

Science.gov (United States)

Culpepper, Erin E; Clayton, Leigh A; Hadfield, Catherine A; Arnold, Jill E; Bourbon, Holly M

2016-06-01

Public aquaria evaluate coliform indicator bacteria levels in fish systems, but the purpose of testing, testing methods, and management responses are not standardized, unlike with the coliform bacteria testing for marine mammal enclosures required by the U.S. Department of Agriculture. An online survey was sent to selected aquaria to document current testing and management practices in fish systems without marine mammals. The information collected included indicator bacteria species, the size and type of systems monitored, the primary purpose of testing, sampling frequency, test methods, the criteria for interpreting results, corrective actions, and management changes to limit human exposure. Of the 25 institutions to which surveys were sent, 19 (76%) responded. Fourteen reported testing for fecal indicator bacteria in fish systems. The most commonly tested indicator species were total (86%) and fecal (79%) coliform bacteria, which were detected by means of the membrane filtration method (64%). Multiple types and sizes of systems were tested, and the guidelines for testing and corrective actions were highly variable. Only three institutions performed additional tests to confirm the identification of indicator organisms. The results from this study can be used to compare bacterial monitoring practices and protocols in fish systems, as an aid to discussions relating to the accuracy and reliability of test results, and to help implement appropriate management responses. Received August 23, 2015; accepted December 29, 2015.

The health care system for female workers and its current status in Japan.

Science.gov (United States)

Nohara, M; Kagawa, J

2000-11-01

In this paper we describe female workers' health care, the women's and maternal protection system within the Japanese legal system, the current status of female workers in Japan, and problems regarding methods of advancing health care and the women's or maternal protection system. Motherhood is respected in the workplace in Japan, and in order to provide an environment in which women can work and still bear and rear children with a sense of security, laws concerning maternal protection of female workers, and revisions in terms of the system have been made, and a new system has been in effect since the fiscal year of 1998. Nevertheless, gender discrimination against women and the disparagement of women, rooted in gender role stereotypes concerning the division of labor, remain firmly planted in the social environment and in long-established custom.

Current state and future direction of computer systems at NASA Langley Research Center

Science.gov (United States)

Rogers, James L. (Editor); Tucker, Jerry H. (Editor)

1992-01-01

Computer systems have advanced at a rate unmatched by any other area of technology. As performance has dramatically increased there has been an equally dramatic reduction in cost. This constant cost performance improvement has precipitated the pervasiveness of computer systems into virtually all areas of technology. This improvement is due primarily to advances in microelectronics. Most people are now convinced that the new generation of supercomputers will be built using a large number (possibly thousands) of high performance microprocessors. Although the spectacular improvements in computer systems have come about because of these hardware advances, there has also been a steady improvement in software techniques. In an effort to understand how these hardware and software advances will effect research at NASA LaRC, the Computer Systems Technical Committee drafted this white paper to examine the current state and possible future directions of computer systems at the Center. This paper discusses selected important areas of computer systems including real-time systems, embedded systems, high performance computing, distributed computing networks, data acquisition systems, artificial intelligence, and visualization.

Load Torque Compensator for Model Predictive Direct Current Control in High Power PMSM Drive Systems

DEFF Research Database (Denmark)

Preindl, Matthias; Schaltz, Erik

2010-01-01

In drive systems the most used control structure is the cascade control with an inner torque, i.e. current and an outer speed control loop. The fairly small converter switching frequency in high power applications, e.g. wind turbines lead to modest speed control performance. An improvement bring...... the use of a current controller which takes into account the discrete states of the inverter, e.g. DTC or a more modern approach: Model Predictive Direct Current Control (MPDCC). Moreover overshoots and oscillations in the speed are not desired in many applications, since they lead to mechanical stress...

Seasonal evolution of S q current system at sub-auroral latitude

Science.gov (United States)

Vichare, Geeta; Rawat, Rahul; Hanchinal, A.; Sinha, A. K.; Dhar, A.; Pathan, B. M.

2012-11-01

The quiet-time (Σ K p ≤ 3) daily variations of the geomagnetic field at the Indian Antarctic station, Maitri (Geographic Coord.: 70.75°S, 11.73°E; Geomagnetic Coord.: 66.84°S, 56.29°E) during two consecutive years of a solar minimum are considered in order to investigate the characteristics of the solar quiet ( S q) current system. The present work reports the signatures of the south limb of the S q current loop of the southern hemisphere over a sub-auroral station. It is observed that the seasonal variation of the S q current strength over Maitri is strongest during the summer months and weakest during the winter months. In spite of the total darkness during the winter months, an S q pattern is identified at Maitri. The range of the horizontal field variation in the daily S q pattern during summer is one order higher than that during winter. An interesting feature regarding the phase of the local time variation in the seasonal pattern is found here. A sharp shift in the time of the peak S q current to later local times (> 1 hour per month) is observed during January-February and July-August, which may correspond to the transition from the complete presence, or absence, of sunlight to partial sunlight. The differences in the incoming solar UV radiation during such transitions can cause a sudden change in the local ionospheric conductivity pattern, and can also trigger some unusual thermo-tidal activity, that might be responsible for modifying the global S q pattern.

Current position on software for the automatic data acquisition system

International Nuclear Information System (INIS)

1988-01-01

This report describes the current concepts for software to control the operation of the Automatic Data Acquisition System (ADAS) proposed for the Deaf Smith County, Texas, Exploratory Shaft Facility (ESF). The purpose of this report is to provide conceptual details of how the ADAS software will execute the data acquisition function, and how the software will make collected information available to the test personnel, the Data Management Group (DMG), and other authorized users. It is not intended that this report describe all of the ADAS functions in exact detail, but the concepts included herein will form the basis for the formal ADAS functional requirements definition document. 5 refs., 14 figs

A Smart Voltage and Current Monitoring System for Three Phase Inverters Using an Android Smartphone Application.

Science.gov (United States)

Mnati, Mohannad Jabbar; Van den Bossche, Alex; Chisab, Raad Farhood

2017-04-15

In this paper, a new smart voltage and current monitoring system (SVCMS) technique is proposed. It monitors a three phase electrical system using an Arduino platform as a microcontroller to read the voltage and current from sensors and then wirelessly send the measured data to monitor the results using a new Android application. The integrated SVCMS design uses an Arduino Nano V3.0 as the microcontroller to measure the results from three voltage and three current sensors and then send this data, after calculation, to the Android smartphone device of an end user using Bluetooth HC-05. The Arduino Nano V3.0 controller and Bluetooth HC-05 are a cheap microcontroller and wireless device, respectively. The new Android smartphone application that monitors the voltage and current measurements uses the open source MIT App Inventor 2 software. It allows for monitoring some elementary fundamental voltage power quality properties. An effort has been made to investigate what is possible using available off-the-shelf components and open source software.

A maximum power point tracking for photovoltaic-SPE system using a maximum current controller

Energy Technology Data Exchange (ETDEWEB)

Muhida, Riza [Osaka Univ., Dept. of Physical Science, Toyonaka, Osaka (Japan); Osaka Univ., Dept. of Electrical Engineering, Suita, Osaka (Japan); Park, Minwon; Dakkak, Mohammed; Matsuura, Kenji [Osaka Univ., Dept. of Electrical Engineering, Suita, Osaka (Japan); Tsuyoshi, Akira; Michira, Masakazu [Kobe City College of Technology, Nishi-ku, Kobe (Japan)

2003-02-01

Processes to produce hydrogen from solar photovoltaic (PV)-powered water electrolysis using solid polymer electrolysis (SPE) are reported. An alternative control of maximum power point tracking (MPPT) in the PV-SPE system based on the maximum current searching methods has been designed and implemented. Based on the characteristics of voltage-current and theoretical analysis of SPE, it can be shown that the tracking of the maximum current output of DC-DC converter in SPE side will track the MPPT of photovoltaic panel simultaneously. This method uses a proportional integrator controller to control the duty factor of DC-DC converter with pulse-width modulator (PWM). The MPPT performance and hydrogen production performance of this method have been evaluated and discussed based on the results of the experiment. (Author)

A precision analogue integrator system for heavy current measurement in MFDC resistance spot welding

International Nuclear Information System (INIS)

Xia, Yu-Jun; Zhang, Zhong-Dian; Xia, Zhen-Xin; Zhu, Shi-Liang; Zhang, Rui

2016-01-01

In order to control and monitor the quality of middle frequency direct current (MFDC) resistance spot welding (RSW), precision measurement of the welding current up to 100 kA is required, for which Rogowski coils are the only viable current transducers at present. Thus, a highly accurate analogue integrator is the key to restoring the converted signals collected from the Rogowski coils. Previous studies emphasised that the integration drift is a major factor that influences the performance of analogue integrators, but capacitive leakage error also has a significant impact on the result, especially in long-time pulse integration. In this article, new methods of measuring and compensating capacitive leakage error are proposed to fabricate a precision analogue integrator system for MFDC RSW. A voltage holding test is carried out to measure the integration error caused by capacitive leakage, and an original integrator with a feedback adder is designed to compensate capacitive leakage error in real time. The experimental results and statistical analysis show that the new analogue integrator system could constrain both drift and capacitive leakage error, of which the effect is robust to different voltage levels of output signals. The total integration error is limited within  ±0.09 mV s −1 0.005% s −1 or full scale at a 95% confidence level, which makes it possible to achieve the precision measurement of the welding current of MFDC RSW with Rogowski coils of 0.1% accuracy class. (paper)

Current status of quantum electrical metrology

International Nuclear Information System (INIS)

Urano, Chiharu; Kaneko, Nobuhisa; Kiryu, Shogo

2005-01-01

Physical background, current status of proof systems and researches of the next generation standards of Josephson voltage and Quantized Hall Resistance (QHR) standard system are described. Josephson effect, the principle and theory of quantized hall effect, usual voltage standard system, standard feed of direct current resistance, and researches of voltage standard and direct current resistance standard are explained. The current-voltage of Josephson element in the usual voltage standard proof system and bias method, outline of typical Josephson voltage standard proof system and GaAs/AlGaAs heterostructure used as resistance standard are stated. Cryogenic Current Comparator (CCC) and Direct Current Comparator (DCC) proofread usual resistor. New Quantum Hall Array Resistance Standard (QHARS) is studied by BNM-LNE group in French, and the other new AC Quantized Hall Resistance (AC-QHR) by the European ACQHE Project. (S.Y.)

Impact of Capital and Current Costs Changes of the Incineration Process of the Medical Waste on System Management Cost

Science.gov (United States)

Jolanta Walery, Maria

2017-12-01

The article describes optimization studies aimed at analysing the impact of capital and current costs changes of medical waste incineration on the cost of the system management and its structure. The study was conducted on the example of an analysis of the system of medical waste management in the Podlaskie Province, in north-eastern Poland. The scope of operational research carried out under the optimization study was divided into two stages of optimization calculations with assumed technical and economic parameters of the system. In the first stage, the lowest cost of functioning of the analysed system was generated, whereas in the second one the influence of the input parameter of the system, i.e. capital and current costs of medical waste incineration on economic efficiency index (E) and the spatial structure of the system was determined. Optimization studies were conducted for the following cases: with a 25% increase in capital and current costs of incineration process, followed by 50%, 75% and 100% increase. As a result of the calculations, the highest cost of system operation was achieved at the level of 3143.70 PLN/t with the assumption of 100% increase in capital and current costs of incineration process. There was an increase in the economic efficiency index (E) by about 97% in relation to run 1.

Current distribution evaluation of dye-sensitized solar cell using HTS-SQUID-based magnetic measurement system

Energy Technology Data Exchange (ETDEWEB)

Sakai, Kenji, E-mail: Sakai-k@okayama-u.ac.jp; Tanaka, Kohei; Kiwa, Toshihiko; Tsukada, Keiji

2016-11-15

Highlights: • Current distribution and direction of dye-sensitized solar cell (DSSC) was measured. • Electrical current flowing in the indium tin oxide (ITO) glass substrate was uniform. • The distribution of electrical current depended on I–V characteristic. • Current direction changed when the performance of DSSC is low. - Abstract: The current flowing inside a dye-sensitized solar cell (DSSC) was measured using a high-temperature superconductor superconducting quantum interference device (HTS-SQUID)-based magnetic measurement system. Further, a new evaluation method of the DSSC, which is difficult to measure using the conventional method, was investigated to improve the characteristics of the DSSC. The tangential components of the magnetic field generated from the DSSC were measured using two HTS-SQUIDs, and the intensity and direction related to the electrical current were obtained by the measured magnetic field. The DSSCs prepared with different dyes and catalytic substances showed different current-intensity mapping. The current direction was different for the DSSC with low performance. In addition, the current flowing in the ITO layer of the ITO glass substrate was also measured and the results confirmed that it had uniform distribution. These results show that the current mapping and the direction of the electrical current depend on the internal factors of the DSSC, and the detection of the magnetic field distribution generated from it is expected to lead to its new evaluation method.

An integrated automatic system for the eddy-current testing of the steam generator tubes

Energy Technology Data Exchange (ETDEWEB)

Woo, Hee Gon; Choi, Seong Su [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center

1995-12-31

This research project was focused on automation of steam generator tubes inspection for nuclear power plants. ECT (Eddy Current Testing) inspection process in nuclear power plants is classified into 3 subprocesses such as signal acquisition process, signal evaluation process, and inspection planning and data management process. Having been automated individually, these processes were effectively integrated into an automatic inspection system, which was implemented in HP workstation with expert system developed (author). 25 refs., 80 figs.

Analytical model development of an eddy-current-based non-contacting steel plate conveyance system

International Nuclear Information System (INIS)

Liu, C.-T.; Lin, S.-Y.; Yang, Y.-Y.; Hwang, C.-C.

2008-01-01

A concise model for analyzing and predicting the quasi-static electromagnetic characteristics of an eddy-current-based non-contacting steel plate conveyance system has been developed. Confirmed by three-dimensional (3-D) finite element analysis (FEA), adequacy of the analytical model can be demonstrated. Such an effective approach, which can be conveniently used by the potential industries for preliminary system operational performance evaluations, will be essential for designers and on-site engineers

An integrated automatic system for the eddy-current testing of the steam generator tubes

Energy Technology Data Exchange (ETDEWEB)

Woo, Hee Gon; Choi, Seong Su [Korea Electric Power Corp. (KEPCO), Taejon (Korea, Republic of). Research Center

1996-12-31

This research project was focused on automation of steam generator tubes inspection for nuclear power plants. ECT (Eddy Current Testing) inspection process in nuclear power plants is classified into 3 subprocesses such as signal acquisition process, signal evaluation process, and inspection planning and data management process. Having been automated individually, these processes were effectively integrated into an automatic inspection system, which was implemented in HP workstation with expert system developed (author). 25 refs., 80 figs.

A β-Ta system for current induced magnetic switching in the absence of external magnetic field

Science.gov (United States)

Chen, Wenzhe; Qian, Lijuan; Xiao, Gang

2018-05-01

Magnetic switching via Giant Spin Hall Effect (GSHE) has received great interest for its role in developing future spintronics logic or memory devices. In this work, a new material system (i.e. a transition metal sandwiched between two ferromagnetic layers) with interlayer exchange coupling is introduced to realize the deterministic field-free perpendicular magnetic switching. This system uses β-Ta, as the GSHE agent to generate a spin current and as the interlayer exchange coupling medium to generate an internal field. The critical switching current density at zero field is on the order of 106 A/cm2 due to the large spin Hall angle of β-Ta. The internal field, along with switching efficiency, depends strongly on the orthogonal magnetization states of two ferromagnetic coupling layers in this system.

Current understanding of interactions between nanoparticles and the immune system

International Nuclear Information System (INIS)

Dobrovolskaia, Marina A.; Shurin, Michael; Shvedova, Anna A.

2016-01-01

The delivery of drugs, antigens, and imaging agents benefits from using nanotechnology-based carriers. The successful translation of nanoformulations to the clinic involves thorough assessment of their safety profiles, which, among other end-points, includes evaluation of immunotoxicity. The past decade of research focusing on nanoparticle interaction with the immune system has been fruitful in terms of understanding the basics of nanoparticle immunocompatibility, developing a bioanalytical infrastructure to screen for nanoparticle-mediated immune reactions, beginning to uncover the mechanisms of nanoparticle immunotoxicity, and utilizing current knowledge about the structure–activity relationship between nanoparticles' physicochemical properties and their effects on the immune system to guide safe drug delivery. In the present review, we focus on the most prominent pieces of the nanoparticle–immune system puzzle and discuss the achievements, disappointments, and lessons learned over the past 15 years of research on the immunotoxicity of engineered nanomaterials. - Graphical abstract: API — active pharmaceutical ingredient; NP — nanoparticles; PCP — physicochemical properties, CARPA — complement activation-related pseudoallergy, ICH — International Conference on Harmonization. Display Omitted - Highlights: • Achievements, disappointments and lessons learned over past decade are reviewed. • Areas in focus include characterization, immunotoxicity and utility in drug delivery. • Future direction focusing on mechanistic immunotoxicity studies is proposed.

Current understanding of interactions between nanoparticles and the immune system

Energy Technology Data Exchange (ETDEWEB)

Dobrovolskaia, Marina A., E-mail: marina@mail.nih.gov [Nanotechnology Characterization Laboratory, Cancer Research Technology Program, Leidos Biomedical Research Inc., Frederick National Laboratory for Cancer Research, NCI at Frederick, Frederick, MD 21702 (United States); Shurin, Michael [Department of Pathology, University of Pittsburgh Medical Center, Pittsburgh, PA 15213 (United States); Department of Immunology, University of Pittsburgh Medical Center, Pittsburgh, PA 15213 (United States); Shvedova, Anna A., E-mail: ats1@cdc.gov [Health Effects Laboratory Division, National Institute of Occupational Safety and Health, Centers for Disease Control and Prevention, Morgantown, WV 26505 (United States); Department of Physiology and Pharmacology, West Virginia University, Morgantown, WV 26506 (United States)

2016-05-15

The delivery of drugs, antigens, and imaging agents benefits from using nanotechnology-based carriers. The successful translation of nanoformulations to the clinic involves thorough assessment of their safety profiles, which, among other end-points, includes evaluation of immunotoxicity. The past decade of research focusing on nanoparticle interaction with the immune system has been fruitful in terms of understanding the basics of nanoparticle immunocompatibility, developing a bioanalytical infrastructure to screen for nanoparticle-mediated immune reactions, beginning to uncover the mechanisms of nanoparticle immunotoxicity, and utilizing current knowledge about the structure–activity relationship between nanoparticles' physicochemical properties and their effects on the immune system to guide safe drug delivery. In the present review, we focus on the most prominent pieces of the nanoparticle–immune system puzzle and discuss the achievements, disappointments, and lessons learned over the past 15 years of research on the immunotoxicity of engineered nanomaterials. - Graphical abstract: API — active pharmaceutical ingredient; NP — nanoparticles; PCP — physicochemical properties, CARPA — complement activation-related pseudoallergy, ICH — International Conference on Harmonization. Display Omitted - Highlights: • Achievements, disappointments and lessons learned over past decade are reviewed. • Areas in focus include characterization, immunotoxicity and utility in drug delivery. • Future direction focusing on mechanistic immunotoxicity studies is proposed.

Current status of development on superconducting magnetic energy storage systems and magnetic refrigeration

International Nuclear Information System (INIS)

Hirano, Naoki

2010-01-01

Superconducting magnetic energy storage (SMES) systems have excellent characteristics as energy-storage equipment in power systems such as high efficiency, quick response, and no deterioration in repetitive operations. There are many projects to develop SMES throughout the world. Since 1991, a national project by the Agency for Natural Resources and Energy Japan has been working to develop an SMES system to control power in power systems. Moreover, SMES has been developed to compensate for momentary voltage dips since 2003. To reduce energy consumption due to prolonged operating times, we developed energy-conserving electrical equipment incorporating refrigerating aggregates such as air conditioners. We conduced R and D to convert magnetic refrigeration and highly-efficient, energy-conserving/environmentally friendly technologies, to practical applications. The current status in the development of SMES to control power systems, bridging to deal with instantaneous voltage dips, and magnetic refrigeration technology will be explained in this paper. (author)

Opportunities for Space Science Education Using Current and Future Solar System Missions

Science.gov (United States)

Matiella Novak, M.; Beisser, K.; Butler, L.; Turney, D.

2010-12-01

The Education and Public Outreach (E/PO) office in The Johns Hopkins University Applied Physics Laboratory (APL) Space Department strives to excite and inspire the next generation of explorers by creating interactive education experiences. Since 1959, APL engineers and scientists have designed, built, and launched 61 spacecraft and over 150 instruments involved in space science. With the vast array of current and future Solar System exploration missions available, endless opportunities exist for education programs to incorporate the real-world science of these missions. APL currently has numerous education and outreach programs tailored for K-12 formal and informal education, higher education, and general outreach communities. Current programs focus on Solar System exploration missions such as the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM), Miniature Radio Frequency (Mini-RF) Moon explorer, the Radiation Belt Storm Probes (RBSP), New Horizons mission to Pluto, and the Thermosphere Ionosphere Mesosphere Energetics and Dynamics (TIMED) Satellite, to name a few. Education and outreach programs focusing on K-12 formal education include visits to classrooms, summer programs for middle school students, and teacher workshops. APL hosts a Girl Power event and a STEM (Science, Technology, Engineering, and Mathematics) Day each year. Education and outreach specialists hold teacher workshops throughout the year to train educators in using NASA spacecraft science in their lesson plans. High school students from around the U.S. are able to engage in NASA spacecraft science directly by participating in the Mars Exploration Student Data Teams (MESDT) and the Student Principal Investigator Programs. An effort is also made to generate excitement for future missions by focusing on what mysteries will be solved. Higher education programs are used to recruit and train the next generation of scientists and engineers. The NASA/APL Summer Internship Program offers a

Phased-array antenna system for electron Bernstein wave heating and current drive experiments in QUEST

International Nuclear Information System (INIS)

Idei, H.; Sakaguchi, M.; Kalinnikova, E.I.

2010-11-01

The phased-array antenna system for Electron Bernstein Wave Heating and Current Drive (EBWH/CD) experiments has been developed in the QUEST. The antenna was designed to excite a pure O-mode wave in the oblique injection for the EBWH/CD experiments, and was tested at a low power level. The measured two orthogonal fields were in excellent agreements with the fields evaluated by a developed Kirchhoff code. The heat load and thermal stress in CW 200 kW operation were analyzed with finite element codes. The phased array has been fast scanned [∼10 4 degree/s] to control the incident polarization and angle to follow time evolutions of the plasma current and density. The RF startup and sustainment experiments were conducted using the developed antenna system. The plasma current (< ∼15 kA) with an aspect ratio of 1.5 was started up and sustained by only RF injection. The long pulse discharge of 10 kA was attained for 40 s with the 30 kW injection. (author)

Health Information System Role-Based Access Control Current Security Trends and Challenges.

Science.gov (United States)

de Carvalho Junior, Marcelo Antonio; Bandiera-Paiva, Paulo

2018-01-01

This article objective is to highlight implementation characteristics, concerns, or limitations over role-based access control (RBAC) use on health information system (HIS) using industry-focused literature review of current publishing for that purpose. Based on the findings, assessment for indication of RBAC is obsolete considering HIS authorization control needs. We have selected articles related to our investigation theme "RBAC trends and limitations" in 4 different sources related to health informatics or to the engineering technical field. To do so, we have applied the following search query string: "Role-Based Access Control" OR "RBAC" AND "Health information System" OR "EHR" AND "Trends" OR "Challenges" OR "Security" OR "Authorization" OR "Attacks" OR "Permission Assignment" OR "Permission Relation" OR "Permission Mapping" OR "Constraint". We followed PRISMA applicable flow and general methodology used on software engineering for systematic review. 20 articles were selected after applying inclusion and exclusion criteria resulting contributions from 10 different countries. 17 articles advocate RBAC adaptations. The main security trends and limitations mapped were related to emergency access, grant delegation, and interdomain access control. Several publishing proposed RBAC adaptations and enhancements in order to cope current HIS use characteristics. Most of the existent RBAC studies are not related to health informatics industry though. There is no clear indication of RBAC obsolescence for HIS use.

Collateral Damage to Satellites from an EMP Attack

Science.gov (United States)

2010-08-01

field into regions of weak magnetic field [Stern. 1989, and references therein]. Birkeland’s work captured the interest of auroral researcher Stormer ...dipole magnetic field [ Stormer , 1907]. Although mathematically elegant, Stormer theory did not prove the existence of radiation belts; it set the stage...Based on work by Stormer , Alfven, and others, and on his experience with the Astron thermonuclear device, N. Christofolis in October 1957 suggested

Maximum power point tracking for PV systems under partial shading conditions using current sweeping

International Nuclear Information System (INIS)

Tsang, K.M.; Chan, W.L.

2015-01-01

Highlights: • A novel approach for tracking the maximum power point of photovoltaic systems. • Able to handle both the uniform insolation and partial shading conditions. • Maximum power point tracking based on current sweeping. - Abstract: Partial shading on photovoltaic (PV) arrays causes multiple peaks on the output power–voltage characteristic curve and local searching technique such as perturb and observe (P&O) method could easily fail in searching for the global maximum. Moreover, existing global searching techniques are still not very satisfactory in terms of speed and implementation complexity. In this paper, a fast global maximum power point (MPPT) tracking method which is using current sweeping for photovoltaic arrays under partial shading conditions is proposed. Unlike conventional approach, the proposed method is current based rather than voltage based. The initial maximum power point will be derived based on a current sweeping test and the maximum power point can be enhanced by a finer local search. The speed of the global search is mainly governed by the apparent time constant of the PV array and the generation of a fast current sweeping test. The fast current sweeping test can easily be realized by a DC/DC boost converter with a very fast current control loop. Experimental results are included to demonstrate the effectiveness of the proposed global searching scheme

Helical system. History and current state of helical research

International Nuclear Information System (INIS)

Yokoyama, Masayuki

2017-01-01

This paper described the following: (1) history of nuclear fusion research of Japan's original heliotron method, (2) worldwide development of nuclear fusion research based on helical system such as stellarator, and (3) worldwide meaning of large helical device (LHD) aiming to demonstrate the steady-state performance of heliotron type in the parameter area extrapolable to the core plasma, and research results of LHD. LHD demonstrated that the helical system is excellent in steady operation performance at the world's most advanced level. In an experiment using deuterium gas in 2017, LHD achieved to reach 120 million degrees of ion temperature, which is one index of nuclear fusion condition, demonstrated the realization of high-performance plasma capable of extrapolating to future nuclear fusion reactors, and established the foundation for full-scale research toward the realization of nuclear fusion reactor. Besides experimental research, this paper also described the helical-type stationary nuclear fusion prototype reactor, FFHR-d1, which was based on progress of large-scale simulation at the world's most advanced level. A large-scale superconducting stellarator experimental device, W7-X, with the same scale as LHD, started experiment in December 2015, whose current state is also touched on here. (A.O.)

Improved automated lumen contour detection by novel multifrequency processing algorithm with current intravascular ultrasound system.

Science.gov (United States)

Kume, Teruyoshi; Kim, Byeong-Keuk; Waseda, Katsuhisa; Sathyanarayana, Shashidhar; Li, Wenguang; Teo, Tat-Jin; Yock, Paul G; Fitzgerald, Peter J; Honda, Yasuhiro

2013-02-01

The aim of this study was to evaluate a new fully automated lumen border tracing system based on a novel multifrequency processing algorithm. We developed the multifrequency processing method to enhance arterial lumen detection by exploiting the differential scattering characteristics of blood and arterial tissue. The implementation of the method can be integrated into current intravascular ultrasound (IVUS) hardware. This study was performed in vivo with conventional 40-MHz IVUS catheters (Atlantis SR Pro™, Boston Scientific Corp, Natick, MA) in 43 clinical patients with coronary artery disease. A total of 522 frames were randomly selected, and lumen areas were measured after automatically tracing lumen borders with the new tracing system and a commercially available tracing system (TraceAssist™) referred to as the "conventional tracing system." The data assessed by the two automated systems were compared with the results of manual tracings by experienced IVUS analysts. New automated lumen measurements showed better agreement with manual lumen area tracings compared with those of the conventional tracing system (correlation coefficient: 0.819 vs. 0.509). When compared against manual tracings, the new algorithm also demonstrated improved systematic error (mean difference: 0.13 vs. -1.02 mm(2) ) and random variability (standard deviation of difference: 2.21 vs. 4.02 mm(2) ) compared with the conventional tracing system. This preliminary study showed that the novel fully automated tracing system based on the multifrequency processing algorithm can provide more accurate lumen border detection than current automated tracing systems and thus, offer a more reliable quantitative evaluation of lumen geometry. Copyright © 2011 Wiley Periodicals, Inc.

Fine-scale variability of isopycnal salinity in the California Current System

Science.gov (United States)

Itoh, Sachihiko; Rudnick, Daniel L.

2017-09-01

This paper examines the fine-scale structure and seasonal fluctuations of the isopycnal salinity of the California Current System from 2007 to 2013 using temperature and salinity profiles obtained from a series of underwater glider surveys. The seasonal mean distributions of the spectral power of the isopycnal salinity gradient averaged over submesoscale (12-30 km) and mesoscale (30-60 km) ranges along three survey lines off Monterey Bay, Point Conception, and Dana Point were obtained from 298 transects. The mesoscale and submesoscale variance increased as coastal upwelling caused the isopycnal salinity gradient to steepen. Areas of elevated variance were clearly observed around the salinity front during the summer then spread offshore through the fall and winter. The high fine-scale variances were observed typically above 25.8 kg m-3 and decreased with depth to a minimum at around 26.3 kg m-3. The mean spectral slope of the isopycnal salinity gradient with respect to wavenumber was 0.19 ± 0.27 over the horizontal scale of 12-60 km, and 31%-35% of the spectra had significantly positive slopes. In contrast, the spectral slope over 12-30 km was mostly flat, with mean values of -0.025 ± 0.32. An increase in submesoscale variability accompanying the steepening of the spectral slope was often observed in inshore areas; e.g., off Monterey Bay in winter, where a sharp front developed between the California Current and the California Under Current, and the lower layers of the Southern California Bight, where vigorous interaction between a synoptic current and bottom topography is to be expected.

INVESTIGATION OF THE DRAWBACKS OF THE CURRENT NOTAM SYSTEM

Directory of Open Access Journals (Sweden)

Mykola Bogunenko

2013-10-01

Full Text Available Normal 0 false false false MicrosoftInternetExplorer4 The article deals with the analysis of the current NOTAM system, investigation of the factors that limit the NOTAM format, analysis of such drawbacks as human interpretation, information overload by the end use, geographical inaccuracy, not-self contained and hidden applicability /* Style Definitions */ table.MsoNormalTable {mso-style-name:"Обычная таблица"; mso-tstyle-rowband-size:0; mso-tstyle-colband-size:0; mso-style-noshow:yes; mso-style-parent:""; mso-padding-alt:0cm 5.4pt 0cm 5.4pt; mso-para-margin:0cm; mso-para-margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:10.0pt; font-family:"Times New Roman"; mso-ansi-language:#0400; mso-fareast-language:#0400; mso-bidi-language:#0400;}

A transformerless single-phase symmetrical Z-source HERIC inverter with reduced leakage currents for PV systems

DEFF Research Database (Denmark)

Li, Kerui; Shen, Yanfeng; Yang, Yongheng

2018-01-01

and thus low leakage currents in PV applications. The symmetric Z-source HERIC inverter requires two extra active switches. Nevertheless, the operation frequency of the two switches is the line frequency, leading to negligible losses. More importantly, the performance in terms of low leakage currents...... and harmonics is improved. Experimental tests are performed to validate the analysis and performance of the proposed system....

Parameter Improved Particle Swarm Optimization Based Direct-Current Vector Control Strategy for Solar PV System

Directory of Open Access Journals (Sweden)

NAMMALVAR, P.

2018-02-01

Full Text Available This paper projects Parameter Improved Particle Swarm Optimization (PIPSO based direct current vector control technology for the integration of photovoltaic array in an AC micro-grid to enhance the system performance and stability. A photovoltaic system incorporated with AC micro-grid is taken as the pursuit of research study. The test system features two power converters namely, PV side converter which consists of DC-DC boost converter with Perturbation and Observe (P&O MPPT control to reap most extreme power from the PV array, and grid side converter which consists of Grid Side-Voltage Source Converter (GS-VSC with proposed direct current vector control strategy. The gain of the proposed controller is chosen from a set of three values obtained using apriori test and tuned through the PIPSO algorithm so that the Integral of Time multiplied Absolute Error (ITAE between the actual and the desired DC link capacitor voltage reaches a minimum and allows the system to extract maximum power from PV system, whereas the existing d-q control strategy is found to perform slowly to control the DC link voltage under varying solar insolation and load fluctuations. From simulation results, it is evident that the proposed optimal control technique provides robust control and improved efficiency.

A Novel Dual-input Isolated Current-Fed DC-DC Converter for Renewable Energy System

DEFF Research Database (Denmark)

Zhang, Zhe; Thomsen, Ole Cornelius; Andersen, Michael A. E.

2010-01-01

In this paper, a novel isolated current-fed DC-DC converter (boost-type) with two input power sources based on multi-transformer structure, which is suitable for fuel cells and super-capacitors hybrid energy system, is proposed and designed. With particular transformer windings connection strategy...

Current status of the 124Xe target system development for the high purity 123I production in KCCH

International Nuclear Information System (INIS)

Chun, Kwon Soo

2002-01-01

This report describes the 124 Xe gaseous target system employed for 123 I production at the Korea Cancer Center Hospital. Currently the control system is manual and will be computerized after the system parameters have been established

CRISPR technologies for bacterial systems: Current achievements and future directions.

Science.gov (United States)

Choi, Kyeong Rok; Lee, Sang Yup

2016-11-15

Throughout the decades of its history, the advances in bacteria-based bio-industries have coincided with great leaps in strain engineering technologies. Recently unveiled clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated proteins (Cas) systems are now revolutionizing biotechnology as well as biology. Diverse technologies have been derived from CRISPR/Cas systems in bacteria, yet the applications unfortunately have not been actively employed in bacteria as extensively as in eukaryotic organisms. A recent trend of engineering less explored strains in industrial microbiology-metabolic engineering, synthetic biology, and other related disciplines-is demanding facile yet robust tools, and various CRISPR technologies have potential to cater to the demands. Here, we briefly review the science in CRISPR/Cas systems and the milestone inventions that enabled numerous CRISPR technologies. Next, we describe CRISPR/Cas-derived technologies for bacterial strain development, including genome editing and gene expression regulation applications. Then, other CRISPR technologies possessing great potential for industrial applications are described, including typing and tracking of bacterial strains, virome identification, vaccination of bacteria, and advanced antimicrobial approaches. For each application, we note our suggestions for additional improvements as well. In the same context, replication of CRISPR/Cas-based chromosome imaging technologies developed originally in eukaryotic systems is introduced with its potential impact on studying bacterial chromosomal dynamics. Also, the current patent status of CRISPR technologies is reviewed. Finally, we provide some insights to the future of CRISPR technologies for bacterial systems by proposing complementary techniques to be developed for the use of CRISPR technologies in even wider range of applications. Copyright © 2016. Published by Elsevier Inc.

Wearable Current-Based ECG Monitoring System with Non-Insulated Electrodes for Underwater Application

Directory of Open Access Journals (Sweden)

Stefan Gradl

2017-12-01

Full Text Available The second most common cause of diving fatalities is cardiovascular diseases. Monitoring the cardiovascular system in actual underwater conditions is necessary to gain insights into cardiac activity during immersion and to trigger preventive measures. We developed a wearable, current-based electrocardiogram (ECG device in the eco-system of the FitnessSHIRT platform. It can be used for normal/dry ECG measuring purposes but is specifically designed to allow underwater signal acquisition without having to use insulated electrodes. Our design is based on a transimpedance amplifier circuit including active current feedback. We integrated additional cascaded filter components to counter noise characteristics specific to the immersed condition of such a system. The results of the evaluation show that our design is able to deliver high-quality ECG signals underwater with no interferences or loss of signal quality. To further evaluate the applicability of the system, we performed an applied study with it using 12 healthy subjects to examine whether differences in the heart rate variability exist between sitting and supine positions of the human body immersed in water and outside of it. We saw significant differences, for example, in the RMSSD and SDSD between sitting outside the water (36 ms and sitting immersed in water (76 ms and the pNN50 outside the water (6.4% and immersed in water (18.2%. The power spectral density for the sitting positions in the TP and HF increased significantly during water immersion while the LF/HF decreased significantly. No significant changes were found for the supine position.