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We describe a photomultiplier high voltage power supply incorporating a piezoelectric ceramic transformer that generates high voltage while operating under a strong magnetic field. The power supply includes feedback to stabilize the high voltage output, supplying from 1500 V to 2500 V with a load resistance of more than 10 M[Omega] at an efficiency higher than 50%.

Devices for handling microparticles using an ac electric field are proposed and experimentally validated. With the application of balanced multiphase high voltages in the 0.2 k[V.sub.p-p] -2 k[V.sub.p-p] range to a series of encased parallel electrodes with atypical center-to-center pitch width of 400 m, particles on a thin protecting and insulating film become charged and are conveyed by the created traveling field. Devices with various novel transportation and manipulation features, utilizing multiphase ac electric fields that instantly generate particle driving forces, have been designed and produced. Their features include newly developed methods for particle conveyance smoothing, grouping, and sorting, as well as two-dimensional handling. Traced particle conveyance characteristics have been studied under application of three and six-phase voltages with three different voltage wave profiles and also in diverse environments. Various particle materials with a 5--400-m-diameter range have been experimentally examined; Fe, AI, glass, and plastic spheres showed the best performances.

There are several numerical methods for calculation of electric fields but they need some sort of experience and trial and error to get the correct solution. A genetic algorithm (GA) based approach is used to eliminate the need for the experience and to save time and effort spent in the trial and error. Two enhancement techniques, namely, Refreshment Method and No-Twins Method, are used with the GA operators to improve the performance of the GA in assessment of high voltage fields. The performance of these two enhancement techniques has been studied for computing the electrostatic field in high voltage applications. [C] 2000 Elsevier Science Ltd. All rights reserved. Keywords: Genetic algorithms; High voltage fields; Charge simulation field calculation method; Rod plane gaps; Refreshment method; No twins method

The conductivity of the human skull was measured both in vitro and in vivo. The in vitro measurement was performed on a sample of fresh skull placed within a saline environment. For the in vivo measurement a small current was passed through the head by means of two electrodes placed on the scalp. The potential distribution thus generated on the scalp was measured in two subjects for two locations of the current injecting electrodes. Both methods revealed a skull conductivity of about 0.015 [Upsilon]/m. For the conductivities of the brain, the skull and the scalp a ratio of 1:1/15:1 was found. This is consistent with some of the reports on conductivities found in the literature, but differs considerably from the ratio 1:1/80:1 commonly used in neural source localization. An explanation is provided for this discrepancy, indicating that the correct ratio is 1:1/15:1. Index Terms--Neural source localization, skull conductivity.

This research concentrates on the application of pulsed corona discharges to crack heavy tar components (hydrocarbons) of thermally generated biogas into lighter ones. The method has the advantage that it can operate at a high temperature and be retrofitted to existing installations. The corona discharge is energized by 100-150-ns-wide voltage pulses (100 kV) at a continuous repetition rate of 600-1000 pulses per second. The power dissipated by the corona discharges is 1.5 kW average and 50 MW peak in each pulse. To be cracked by discharges, the hydrocarbons of the tar mixture need to be gaseous, and therefore, the corona reactor must operate at a high temperature. During this first phase of the program, the reactor runs at a modest temperature of up to 200 [degrees] C. The reactor is a 3-m-long stainless steel cylinder, 0.25-m diameter with a corona wire along the axis. The pressure is 1 atmosphere. Index Terms--Biogas, discharge cleaning, electromagnetic compatibility, high voltage, hot gas cleanup, pulsed corona, pulsed power, tar removal.

Audible noise (AN) produced by corona discharges from high voltage transmission lines is one of the more important considerations in line design. Therefore, line designers must predetermine the AN using prediction formulas. This paper presents the results of applying evolutionary computation techniques using AN data from lines throughout the world to develop new, highly accurate formulas for predicting the A-weighted AN during heavy rain and stable rain from overhead ac lines. Calculated AN's using these new formulas and existing formulas are compared with measured data. Index Terms--AN database, audible noise prediction, corona, evolutionary computations, genetic algorithm, genetic programming, transmission line design.

The dependence of magnetoresistance (MR) ratio and pinning characteristics on the two pinning layer thicknesses, in synthetic ferrimagnetic (SF) structure (P2/Ru/P1/AF), was investigated. The pinning field decreased monotonically when [Delta]t (=[t.sub.P2] - [t.sub.P1]) = 0 while it has its maximum at a specific [t.sub.P2] when [Delta]t (=[t.sub.P2] - [t.sub.P1]) [is not equal to] 0 as [t.sub.P2] increased. MR ratio reached its maximum at a specific [t.sub.P2] as [t.sub.P2] increased. In the case of the fixed [t.sub.P2], pinning field decreased whereas MR ratio increased as [Delta]t increased. This trend is also found when the total thickness of P1 and P2 is fixed so that the current shunting to synthetic ferrimagnet (SF) trilayer is fixed. Both strong pinning field and sufficient MR ratio could be obtained by selecting appropriate [Delta]t under the constraint of constant total thickness of SF trilayer. Index Terms--Giant magnetoresistance, pinning field, spin-valve, synthetic ferrimagnet.

Effect of hydrogen peroxide on the membrane currents of sinoatrial node cells from rabbit heart. Am J Physiol Heart Circ Physiol 279: H992-H999, 2000.--The effects of [H.sub.2][O.sub.2] on pacemaker activity and underlying membrane currents were studied in isolated rabbit sinoatrial (SA) node cells using perforated patch current- and voltage-clamp methods. Short-term exposure ([is less than] 10 min) of the nodal cells to [H.sub.2][O.sub.2] (200 [micro]M) resulted in an initial shortening of spontaneous action potential cycle length (from 445 [+ or -] 60 to 398 [+ or -] 56 ms; P [is less than] 0.05) and a prolongation of action potential duration. [H.sub.2][O.sub.2] (100 [micro]M) significantly increased peak L-type [Ca.sup.2+] current ([I.sub.Ca,L])from -384 [+ or -] 77 to -439 [+ or -] 84 pA (116 [+ or -] 2%, n = 6). Additionally, the persistent or non-inactivating component of [I.sub.Ca,L] was increased from -52 [+ or -] 3 to -88 [+ or -] 14 pA (174 [+ or -] 19%, n = 6). The hyperpolarization-activated current ([I.sub.f]) was decreased from -228 [+ or -] 62 to -161 [+ or -] 72 pA after exposure to [H.sub.2][O.sub.2] (n = 7). There were no changes in the delayed rectifier [K.sup.+] current ([I.sub.K]) (n = 7). [H.sub.2] [O.sub.2]-induced [Ca.sup.2+] currents were blocked by 2 [micro]M nicardipine (n = 6), 2 mM [Ni.sup.2+] (n = 2), and the protein kinase C (PKC) inhibitor bisindolylmaleimide ([10.sup.-7] M; n = 4) but not by 20 [micro]M tetrodotoxin. These results suggest that [H.sub.2][O.sub.2] can increase the spontaneous pacing rate in rabbit SA node cells by enhancing [I.sub.Ca,L] and that this effect is mediated by a PKC-dependent pathway. patch clamp; action potential; potassium ion current; hyperpolarization-activated current; calcium ion current, sinoatrial nodal cells

A CCC has superior commutation ability when compared to a line commutated converter used in a conventional HVdc system. This paper models the commutating and post commutation period of the converter circuit in theoretical style, and formularize the commutation and extinction equation with mathematical treatment. The equations express the relations among firing angle, overlap angle, effective margin angle, state variables and converter parameters, and compose nonlinear simultaneous equations. The fine CCC commutation characteristics are shown by using the equations to several commutation capacitor configurations. The authors propose the predictive firing angle calculation method for the constant margin angle control (A[Gamma]'R) operation of a CCC-HVdc system as the practical application of the obtained equations. The obtained equations cannot be solved algebraically for their complexity, then convergence calculations of numerical analysis are assessed, but it is hard to secure the derivation to the various operating conditions. The authors propose to apply an approximate polynomial equation from the off line calculated characteristics to achieve the firing angle predicting equation. The design index for approximation polynomial of A[Gamma]'R is presented to make the polynomials to low order. The suitability of the proposed predictive A[Gamma]'R is studied with simulations by applying it to the converter controller and it can make the most of the CCC availability. Index Terms--CC, CCC, effective margin angle, firing angle predictions, HVdc.

A shunt active filter based on the instantaneous active and reactive current component [i.sub.d]-[i.sub.q] method is proposed. This new control method aims to compensate harmonics and first harmonic unbalance. To evaluate its relative performance it is compared with the instantaneous active and reactive power p-q method under various mains voltage conditions and for different harmonic injection high-pass filters. Both methods are completely frequency-independent, however under distorted mains voltages the proposed method presents a better harmonic compensation performance. The system synthesis and implementation are performed. Simulation and experimental results are presented. Index Terms--Active Filters, id-iq method, p-q method.

The effect of including an inductance in the circuit of a glow-discharge-pulsed electron gun for materials processing is analyzed. Due to the particular nonlinear behavior of the current vs voltage in these guns, and the strong nonlinear self-focusing of the beam, the adequate shaping of the temporal profile of the discharge becomes relevant to the efficiency of the system. A critical damping value for the inductance is obtained and within the range of practical interest, analytical expressions are derived for the required inductance, capacitance and source voltage for a given peak power, pulse duration, gas pressure, and pulse shape. The efficiency increase with the improved design is also discussed. Index Terms--Electron gun, glow discharge, surface treatment.

COOL IMAGES Seeing Fields Moving a magnet through a wire coil to generate a current, reproducing what Michael Faraday first noticed around 1821, is a neat experiment to watch. But [...]

The A distribution describes the statistical behavior of the measured square of the electric or magnetic field in an externally illuminated overmoded cavity. An approximation of the individual phase-quadrature fields is derived from this distribution. Numerical evaluation of this approximation to the squared phase-quadrature fields convolved with itself shows good agreement ([+ or -]1% away from the tail of the distribution) with the original A distribution. Comparison of theoretically derived cable currents with experimental data exhibits considerably better than factor-of-two correspondence. Index Terms--Cable currents, X-square distributions, Kolmogorov-Smirnov test, A distribution, Lehman distribution, overmoded enclosures, small apertures, statistical electromagnetics, statistical independence.

This paper reports the experimental results of the development of a novel capacitive divider for high-voltage pulse measurements. The low-voltage (LV) arm capacitor was prepared by thermally growing silicon oxide on commercially available silicon wafers to form capacitors of very large capacitance per unit area ([is greater than] 10 nF with 2-[micro]m oxide thickness on a 30-mm-diameter wafer). With the proposed design for LV arm capacitance, divider ratios of the order [is greater than] 10 000 can easily be obtained. Index Terms--Capacitive, dividers, high voltage, pulse measurements, resistive, response time.

This paper reviews application of all three types of low-voltage circuit breakers for three-phase fault interrupting duty by reference to the circuit breaker's interrupting requirement and rating. After a discussion of the rating process for circuit breaker design and the fault-current evaluation process for circuit breaker application, it then considers the effect of the erroneous assumption that the load-side bolted fault interrupting let-through current of all circuit breakers is equal to the calculated line-side prospective fault current. Index Terms--Circuit breaker, interrupting, let-through, low voltage, rating.

Recently back-to-back HVdc systems have greatly increased. They interconnect large power systems offering numerous technical and economic benefits. The design of AC system filters, however, is not an easy task. Also, filters do not remove all the harmonics for which they are tuned, are costly and have a complicated transient behavior. In this paper a 36-pulse filterless configuration for back-to-back HVdc systems is proposed, whereby harmonics are eliminated within the converter, thus opening the possibility of advantages in aspects of design, reliability and capital savings. Index Terms--HVdc Systems, Filters, Harmonics.

The subject of this paper is the analysis of the behavior of an ac/HV (400 kV) cable line, compensated with shunted inductors, in the event of a fault. Comparisons are made between, and the consequences assessed for a three-phase, single and double phase-to-ground short circuit, starting from various operating conditions. The paper presents criteria applied for assessing the worst fault and the influence of compensating parameters under fault conditions, and for locating the most severe type of fault. Index Terms--Cable Transmission Lines, Short Circuits.

Zinc oxide surge arresters using zinc oxide (ZnO) elements have been widely used for insulation coordination in the world power systems. These ZnO elements have basically reference voltage of about 200 V/mm. Recently, new ZnO elements having about 1.5, 2 times high voltage gradient zinc oxide element have been developed. This paper describes applications of high voltage gradient 300 V/mm ZnO elements to high performance porcelain type surge arresters and oil immersed surge arresters, and 300 V/mm or 400 V/mm ZnO elements to gas insulated tank type surge arresters for power system. Adequate selection of voltage gradient of ZnO elements makes more compact design of the surge arresters. Index Terms--Surge Arrester, Zinc Oxide Elements.

In recent years, online condition assessment of high voltage equipment is increasingly asked for by power utilities. However, most systems on the market today are merely monitoring solutions with hardly any diagnostic capabilities. This report reviews the basic principles for condition diagnosis from the field of artificial intelligence and introduces a novel strategy, named Model-Aided Diagnosis (MAiD). It was initially developed for condition assessment of high voltage circuit breakers but is also suitable for other technical devices. Theoretical considerations as well as practical results show that MAiD is a useful strategy for condition assessment. In addition, with its low hardware requirements it allows online condition diagnosis of high voltage circuit breakers locally by a low-cost monitoring device. Index Terms--Fault diagnosis, circuit breakers, modeling.

The light-triggered thyristor (LTT), which can be directly fired by light, does not need gate electronics on the high-voltage side and is thus a near-ideal semiconductor device for a HVDC valve. In providing an overvoltage protection for LTT without losing its advantage of simple circuits associated with the thyristor, the overvoltage protection system adopted to the conventional electrically triggered thyristor is not necessarily appropriate. We have shown that high-speed protective gate pulses generated from the valve base electronics together with the valve arrester are sufficient for the LTT valve overvoltage protection. The adequacy of this protection strategy is demonstrated by factory type tests and also excel lent service experiences. Index Terms--HVDC, Thyristor valve, LTT, Overvoltage protection, Forward recovery protection.

Thermally induced current in low noise polymeric coaxial cables can introduce significant errors in certain applications. For e-beam crosslinked polymeric cable, the thermally induced current signal can be as high as 1 nA/m. The origin of such thermally induced signals is explained, based on the change of morphology and dielectric polarization as a function of temperature. The results of measurements carried out on three types of cables over a wide range of temperature are in good agreement with numerical simulations which involve the nonlinear thermal properties of the cable materials.

This paper proposes the optimal planning of large passive-harmonic-filters set at high voltage level based on multi-type and multi-set of filters, from which, the types, set numbers, capacities and the important parameters of filters are well determined to satisfy the requirements of harmonic filtering and power factor. Four types of filters, namely single-tuned filter, second-order, third-order and C-type damped filters are selected for the planning. Firstly, the characteristics of filters are analyzed. The cost function and the constraints of filters and system are constructed for formulating the optimization problem of the planning of filters. Secondly, the simulated-annealing (SA) algorithm for searching optimal solution of planning of filters is developed. Finally, three cases of filter planning are presented to show that the superiority and availability of the SA algorithm and proposed planning results of filters. Index Terms--High Voltage, Large Capacity, Optimal Planning, Passive-Harmonic-Filter.

This paper presents the development of a prototype of a substation of 145 kV, BIL 650 kV, taking into account the decrease of the bus electrical insulation clearance, combined with the installation inside a metallic building. Only conventional equipment, usually found on the market, were applied in the prototype. During the preliminary approach, tests were carried out in the High Voltage Laboratory, using different bus-bar configurations and equipment, as circuit breaker, current transformers, potential transformers, switches, and insulators, applying models with metallic wall. The proposed prototype was then built and fully tested according to the IEC recommendations, mainly from the point of view of lightning discharge withstand. The paper shows the layout and clearances used in the model. The result of the tests in the prototype of the compact substation for 145 kV, with BIL 650 kV, is also presented, proving the feasibility of the new proposal. Index Terms--Compact substation, high voltage, high voltage tests, insulation clearance, prototype, substation, tolerance.

This paper presents a single-phase auto-reclosing study of a 500 kV Vietnamese transmission line. The success of the single-phase auto-reclosing depends on the extinction of the secondary arc. Therefore, the influences of several factors such as shunt and neutral reactors, faulted phase and location, capacitive and inductive coupling and series capacitor discharge on the extinction of secondary arc are investigated. This paper presents the influence of single-phase auto-reclosing on the transient stability of the Vietnam system. A new method in order to reduce the dead time for single-phase auto-reclosing is proposed. Index Terms--Recovery voltage, secondary arc current, single-phase auto-reclosing, stability.

The practical use of optical sensors to measure direct high voltages can be limited by their high sensitivity. A new optical high voltage measurement technique for applying to high voltage levels up to 400 kV in a wide bandwidth between dc to 30 MHz is developed. A prototype of the optical voltage transformer is assembled using Pockels crystals in multisegmented arrangement, a super luminescent diode (SLD) light source and a special optical fiber link. A good performance of linearity and accuracy is obtained for dc, ac, lightning impulse, and step voltage measurements. In addition, an excellent agreement is observed between the measured and predicted values. Index Terms--High voltage, optical fiber sensors, optical measurements, optical transducers, Pokels effect.

A new implementation for a floating controlled resistance operating in class AB is introduced. This uses a new translinear mixed loop of eight bipolar transistors. The circuit has been biased with dc current in such a way that it works effectively in class AB. A new building block, the third-generation controlled conveyor (CCCIII) is then implemented. This has been obtained simply by adding a supplementary output terminal Z to duplicate the current flowing through the controlled resistance above. Simulation results, using the nominal parameters of the ALA200 bipolar arrays from ATT, demonstrate the high possibilities of the circuit. With [+ or -] 1.5 V supply voltage, the power consumption of this wideband conveyor (-3 dB bandwidths greater than 30 MHz) is less than 7 mW as soon as the controlled resistance becomes lower than 250 [Omega]. An application example, consisting of a sinusoidal controlled oscillator, implemented from a transimpedance operational amplifier, is finally given to illustrate the versatility of the circuit. Index Terms--Bipolar transistors, controlled oscillators, current conveyors, current mode circuits, floating resistances, translinear circuits.

This paper develops an analytical model for the unaligned inductance of the switched reluctance motor. The analytical model is useful as long as the machine's stator and rotor poles do not overlap and its iron does not saturate. Iron saturation is almost never experienced when the rotor is in the unaligned position for practical winding currents. This paper expands on results presented previously to include the contribution to the unaligned inductance of the flux in both the stator slot and the rotor slot. The approximations that are inherent to the analytical model are stated, and a detailed development of the model is provided. Finally, the paper compares predictions of the unaligned inductance computed by the analytical model to those obtained by finite-element analysis for three different machines with different pole counts and rotor diameters.

The MR ratio of multilayer GMR sensors with the CPP (current perpendicular to the plane) structure is expected to be much larger than that of CIP (current in the plane) sensors. We investigated the GMR properties of CIP and CPP elements of a [Co.sub.0.9][Fe.sub.0.1]/Cu 10-bilayer. For CPP elements, GMR film was connected to the top and bottom terminal layers with a micron-sized contact hole. The measured data was analyzed using a model taking into account of the distribution of sense current. The measured resistance change ([Delta] R) increased rapidly as the GMR diameter became smaller, and showed close agreement with the calculated results when we assumed the MR ratio of CPP films to be around 30%. This MR ratio was twice as large as that of the CIP film of [Co.sub.0.9][Fe.sub.0.1]/Cu 10-bilayer. In this study, we used the CPP elements which had wide GMR films and fine contact holes. So, the measured saturation field ([H.sub.s]) of the CPP elements was almost constant as a function of the contact hole dimension, because the demagnetization field was insensitive to the sensor size. The CPP element in this study will obtain a high output when the GMR diameter becomes small. Index Term--current perpendicular to the plane (CPP), current in the plane (CIP), CoFe/Cu, GMR

The magnetic field dependence of the Fiske steps in a small Josephson junction with a peak critical current density distribution is studied. The maximum current of the resonant states is also determined for the periodic and nonperiodic distribution of peaks in the current density along the junction. It is shown that nonperiodic peak distribution affects the maximum amplitude of the Fiske steps and the magnetic fields where these occur.

A new three-input single-output voltage-mode universal biquadratic filter with high-input impedance using only three plus-type second-generation current conveyors (CCIIs) is presented. The proposed configuration uses only two capacitors and two resistors and can realize all the standard filter functions, that is, high-pass, bandpass, low-pass, notch, and allpass filters without changing the passive elements. The proposed circuit has no requirements for component matching conditions. The use of only plus-type CCIIs simplifies the configuration. Index Terms--Active filters, current conveyors.

The numerical evaluation of the derivative of the parabolic cylinder function, [D[prime].sub.p](z), is described for the argument z = x[e.sup.-i[Pi]/4] and order p = -1/2 + iy, with x and y real.

Some new results related to characteristic impedances of undercut lines are presented, considering various line geometries.

The current-voltage characteristics of Na/p-GaP(110) Scottky barrier diodes were investigated using x-ray photoemission spectroscopy. The results showed that the Schottky barrier height of the material was 1.10 eV, a value consistent with a general weak metal dependence for barrier formation. In addition, metal electronegativity was dependent on the Schottky barrier diode height of the system.

A new formulation of the current within the London approximation allows the calculation of ring currents in topologically complex molecules. Application of this theory to [C.sub.60] demonstrates the existence of remarkable π electron ring currents. Paramagnetic currents, in size comparable to the ones in benzene, flow within the pentagons, whereas weaker diamagnetic currents flow all around the [C.sub.60] molecule. The overall vanishing ring-current magnetic susceptibility results from a cancellation of diamagnetic and paramagnetic contributions. The presence of ring currents significantly affects chemical shifts as measured in nuclear magnetic resonance experiments. In contrast to the magnetic susceptibility, which is a property of the molecule as a whole, chemical shifts are sensitive to the local magnetic field and the effect of ring currents does not vanish., The initial suggestion by Kroto and co-workers [1] that the sea of π electrons on the inner and outer surface of [C.sub.60] could give rise to remarkable ring currents has [...]

Switching-in of short-circuit current leads to pre-arcing in the switching device. Pre-arcing affects the ability of switchgear to close and latch. In three-phase systems, making is associated with transient voltage phenomena that may have a significant impact on the duration of the pre-arcing period. An analysis is presented of these transients. It was found that pre-arcing times in three-phase systems can be considerably prolonged with respect to a single phase situation. On the other hand, it is demonstrated that the three-phase interaction has a moderating influence on the peak value of asymmetrical current. A test-circuit is described, able to perform three-phase synthetic make tests up to 245 kV at current up to 63 kA, representing all transient phenomena. Specific tests are described requiring the maximum available laboratory power: one with a circuit breaker subjected to direct test and one with a high-speed grounding switch subjected to synthetic tests. Index Terms--(AC) circuit breakers, arc discharges, circuit breaker testing, circuit transient analysis, short circuit currents, switchgear testing, switching transients.

The author notes that a small can floating in water will be attracted by a charged plastic rod, though a thin piece of metal will be repelled. He then repeats the question posed by a friend about why this happens and requests answers from readers.

This paper describes a dual-polarized rectenna capable of producing a 50-V output voltage that can be used for driving mechanical actuators. This study demonstrates a circuit topology that allows the output of multiple rectenna elements to be combined in order to step up the output voltage. In this paper, an independent rectifying circuit is used for each of two orthogonal polarizations. By proper combination, the output voltage is doubled over that of the single polarization case. Such panels are being explored for use on the next-generation space telescope to eliminate wiring between actuators and provide for true mechanical isolation. Index Terms--Actuators, free-space power combining and rectification, microstrip patch, rectenna.