The effect of coil parameters on the distribution of steep-frontedsurges in machine windings

The authors identify the coil parameters that are of importance, when assessing interturn voltages produced by steep-fronted transients. The studies are based on a multiconductor transmission line computer model of a machine winding energized by a simple ramp function. Variations in interturn voltages produced by changes in insulation thickness, insulation permittivity, turn geometry, coil length and number of turns are examined and certain guidelines for avoiding high interturn voltages are evaluated. An application study is included to show how interturn voltages can be significantly reduced by applying these guidelines     

Influence of corticotropin-releasing factor on pancreatic and islet blood flow in different regions of the rat pancreas

Corticotropin-releasing factor (CRF) has previously been shown to selectively dilate the mesenteric vascular bed, without affecting other vascular beds. Pancreatic blood flow and islet blood flow were therefore measured separately with a microsphere technique in the two regions of the rat pancreas perfused by the superior mesenteric artery (SMA) or celiac artery (CA) respectively. Intravenous infusion of CRF (0.25 microgram/kg b.w./min) caused an increase in both whole pancreatic blood flow and islet blood flow in the region of the pancreas perfused by the SMA. The fraction of whole pancreatic blood flow diverted through the islets in this part of the pancreas was, however, unaffected by CRF infusion (approximately 10%). CRF did not change either pancreatic or islet blood flow in the CA-perfused part of the pancreas, and did not affect the release of insulin.     

Large-scale quantum mechanical simulations of high- Z metals

High-Z metals constitute a particular challenge for large-scale ab initio electronic-structure calculations, as they require high resolution due to the presence of strongly localized states and require many eigenstates to be computed due to the large number of electrons and need to accurately resolve the Fermi surface. Here, we report recent findings on high-Z metals, using an efficient massively parallel planewave implementation on some of the largest computational architectures currently available. We discuss the particular architectures employed and methodological advances required to harness them effectively. We present a pair-correlation function for U, calculated using quantum molecular dynamics, and discuss relaxations of Pu atoms in the vicinity of defects in aged and alloyed Pu. We find that the self-irradiation associated with aging has a negligible effect on the compressibility of Pu relative to other factors such as alloying. The US Goverment’s right to retain a non-exclusive, royalty-free license in and to any copyright is acknowledged.     

SURFACE ALLOYING OF MILD STEEL BY LASER MELTING OF AN ELECTROLESS NICKEL DEPOSIT CONTAINING CHROMIUM CARBIDES

It is possible to realize surface alloys by laser melting an electroless nickel layer containing chromium carbide particles predeposited on a mild steel substrate. By this way the surface alloy is expected to have not only a high nickel content but also an important chromium content in order to improve the corrosion resistance. The presence of chromium in solid solution results from the dissolution or melting of the carbide particles. Typical laser solidification microstructures are obtained. Dendrites consist of an austenitic Fe-Ni-Cr solid solution and interdendritic regions are constituted by an eutectic mixture containing the same austenitic solid solution and complex Fe, Ni, Cr carbides and phosphides. In comparison with a surface alloy obtained by laser melting of an electroless nickel layer without carbide particles, the corrosion resistance was slightly improved in saline aqueous solutions. The limited effect was due to the fact that the final chromium content in the present experimental conditions was not as high as that initially expected.     

A novel soft-switching full-bridge DC/DC converter: analysis,design considerations, and experimental results at 1.5 kW, 100 kHz

The addition of an external commutating inductor and two clamp diodes to the phase-shifted PWM (pulsewidth modulated) full-bridge DC/DC converter substantially reduces the switching losses of the transistors and the rectifier diodes, under all loading conditions. The authors give analyses, practical design considerations, and experimental results for a 1.5 kW converter with 60 V, 25 A output, operating at 100 kHz clock frequency and 95% efficiency     

Monte-Carlo Simulation of Clocked and Non-Clocked QCA Architectures

We present a Monte Carlo simulation of two implementations of Quantum Cellular Automaton (QCA) circuits: one based on simple ground state relaxation and the other on the clocked cell scheme that has recently been proposed by Tóth and Lent. We focus on the time-dependent behavior of two basic circuits, a binary wire and a majority voting gate, and assess their maximum operating speed and temperature requirements for different sets of fabrication parameters.     

Electrophysical Characteristics of a Posistor Block

The influence of the parameters of posistor elements and the conditions of their heat exchange on the electrical and dynamic characteristics of a posistor block have been investigated. Good agreement between calculation results and experimental data has been established.