PES News

This paper presents a new method for the generation of a reference voltage for a dynamic voltage restorer (DVR). These voltages, when injected in series with a distribution feeder by a voltage source inverter, can tightly regulate the voltage at the load terminal against imbalance or harmonics in the source side. It is stipulated that the DVR does not supply any real power in the steady state. The reference voltage generation scheme is validated through digital computer simulation studies.     

Propagation of a quasi-shear horizontal acoustic wave in Z-Xlithium niobate plates [and conductivity sensor application]

It is found that an acoustic wave which is nearly polarized in the shear horizontal (SH) direction can propagate along the X axis of a Z-cut lithium niobate plate if the ratio h/λ, where h=plate thickness and λ=acoustic wavelength, is less than about 0.5. Attractive properties of this quasi-SH wave include: (1) phase velocity nearly constant for all values of h/λ; (2) ability to propagate in contact with a liquid medium; and (3) electromechanical coupling coefficient as high as 0.15. These properties make the wave attractive for use in a variety of sensor and signal processing applications. An example of sensor applications is illustrated by using the wave to measure conductivity of liquids (aqueous KCl solution). The frequency of a 12-MHz quasi-SH mode oscillator fabricated on a 0.48 wavelength thick Z-X lithium niobate plate is found to vary by more than 80 kHz for variation in KCI concentration from 0 to 0.15%     

印度分布式发电的发展现状

全球约18亿多人口存在电力供应不足状况,这些人大多数居住在发展中国家的偏远地区。尽管许多发展中国家正在努力实施农村电力方案,但据观察,财政困难仍然是执行的首要瓶颈问题。政府正在努力扩大农村地区的电网,但同时也面临着如无法回收成本、缺乏切实可行的价格机制等一系列问题。     

A scaling law for membrane permeabilization with nanopulses

Experimental studies of plasma membrane permeabilization, caused by single, intense, submicrosecond square wave pulses, indicate that the product of electric field amplitude and pulse duration (the electrical impulse) can be considered a similarity or scaling factor. A model based on the hypothesis that the intensity of membrane permeabilization effects is linearly dependent on the electric charge transferred through the permeabilized membrane, provides results, which are consistent with the empirical observations. For multiple pulses, bioelectric effects caused by ultrashort pulses were found to scale with the square root of the pulse number. This square root dependence on the pulse number points to a statistical motion of cells between pulses with respect to the applied electric field, and can be explained using an extension of the random walk statistical results to random rotations. Besides membrane permeabilization, the scaling law has also been shown to hold for secondary bioelectric effects, which are caused by permeability changes in the plasma membrane or subcellular membranes.     

Design of Dual-Band Beam Switching Array for Adaptive Antenna Applications Using Hybrid Directional Coupler and E-Shape Slot Radiator

Wireless Personal Communications - Applications of wireless sensor networks (WSNs) are increasing tremendously to facilitate and establish a link between the physical world and information system....     

Improved Multilevel Hysteresis Current Regulation and Capacitor Voltage Balancing Schemes for Flying Capacitor Multilevel Inverter

This paper focuses on the development of multilevel hysteresis current regulation strategies. Two such strategies have been discussed and some modifications in their control tasks have been proposed to achieve more reliable and improved performance. In general, the multiband concept has been used while making the proposals. The hysteresis band size considerations have also been presented by taking into account the desired and existing system conditions. The proposed modulation schemes have been applied to a five-level flying-capacitor inverter, whose operation under hysteresis current control mode is much less established. A new method of flying-capacitor voltage balancing is proposed which ensures balanced flying-capacitor voltages and, at the same time, maintains the desired current profile. It uses a time-based approach for controlling the capacitor voltages and achieves appreciable voltage spectrum under wide range of load power factor conditions. The performance of the proposed strategies is confirmed through both simulation and experimental investigations.     

Direct analytical solution for the electric field distribution atthe conductor surfaces of coplanar waveguides

A new analytical method of evaluating the electric field distribution across the conductor surfaces of coplanar waveguides (CPWs) is presented. Here, a series of conformal mappings are used to transform the CPW's geometry and field distribution into a uniform image domain, to facilitate a direct field solution. The cumulative electric flux distribution across each conductor surface within the dielectric substrate is studied, and its effects on coupling and propagation modes are described. Direct solutions for the quasi-static normal electric field components are presented together with their graphical representations. Numerical computations show how the total electric flux terminating on the CPW's conductor surfaces varies in terms of the CPW's geometry and substrate parameters     

Effects of transverse doping variations on the transient responseof silicon avalanche shaper devices

Two-dimensional (2-D) drift-diffusion simulations were performed to study the transient response of silicon avalanche shaper (SAS) devices that are used in high-power switching and pulse sharpening applications. The role of transverse doping variations on the transient device response has been studied. Our results clearly reveal a potential for filamentary current conduction. The filamentation, however, is shown to be strongly dependent on the transverse doping characteristics, and hence in principle, could he tailored