A Dynamic Model for a Single Helicopter in the Low Airspace with Telegraph Poles and Electrical Wire

In this paper, we propose a dynamic model for a single helicopter in the low airspace with telegraph poles and electrical wire. The numerical results show that the proposed model can qualitatively describe the helicopter＇s velocity, safe distances, and safe sphere when it runs across the obstacle consisting of telegraph poles and electricaJ wire.

Evaluating transmission towers potentials during ground faults

During ground faults on transmission lines,a number of towers near the fault are likely to acquire high potentials to ground.These tower voltages,if excessive,may present a hazard to humans and animals.This paper presents analytical methods in order to determine the transmission towers potentials during ground faults,for long and short lines.The author developed a global systematic approach to calculate these voltages,which are dependent of a number of factors.Some of the most important factors are:magnitudes of fault currents,fault location with respect to the line terminals,conductor arrangement on the tower and the location of the faulted phase,the ground resistance of the faulted tower,soil resistivity,number,material and size of ground wires.The effects of these factors on the faulted tower voltages have been also examined for different types of power lines.

Macro Model Study for Nonlinear Spring of Tense Torsion Bar in Gap-Closing Type Electrostatic Micromirror

Nonlinear spring characteristics of the tense torsion bar in the gap-closing type electrostatic micromirror are examined. The macro model is introduced for the experimental study. The tension applied in the torsion bar is well controlled using the electromagnetic attraction. This controllability is suited for clearing the nonlinear nature. The tension is confirmed to have the effect to widen the controllable angle range of the mirror suppressing the pull-in. The pull-in angle is observed to increases to about 74% of the mechanical limit angle at the tension of 0,96 N. This is significantly larger than 44% of the case with the linear spring. The larger resonant frequency is maintained. The hardening of the spring can keep the balance with the electrostatic force over the limit of the linear spring. The observed features are explained reasonably with the combination of twisting and bending displacements of the torsion bar.

诗有法,意有度(反方)

从题材的角度来讲,《电线杆》所反映的电力工人、电工师傅辛苦劳作的场景的确让人觉得眼前一亮,因为它有别于时下常见的对心灵迷宫的观光游览,和之前“底层”的凄冷、暗淡也不太一样,它显得更加外向,更加富有生活现场、工作现场的力度与质感,更加言之有物,就立场和意义而言还让人遥遥想起前些年关于“人民性”的讨论。

Complete thermoelectric benchmarking of individual InSb nanowires using combined micro-Raman and electric transport analysis

Nanowires （NWs） are ideal nanostructures for exploring the effects of low dimensionality and thermal conductivity suppression on thermoelectric behavior. However, it is challenging to accurately measure temperature gradients and heat flow in such systems. Here, using a combination of spatially resolved Raman spectroscopy and transport measurements, we determine all the thermoelectric properties of single Se-doped InSb NWs and quantify the figure of merit ZT. The measured laser-induced heating in the NWs and associated electrical response are well described by a 1D heat equation model. Our method allows the determination of the thermal contact resistances at the source and drain electrodes of the NW, which are negligible in our system. The measured thermoelectric parameters of InSb NWs agree well with those obtained based on field-effect transistor Seebeck measurements.

Alignment control for a long span urban rail-transit cable-stayed bridge considering dynamic train loads

In this paper, bridge alignment control with considering dynamic train loads was experimentally and theoretically investigated.Analytical process of bridge dynamics and the self-adaptive Kalman filter bridge alignment control method with considering the dynamic train loads were briefly introduced. The static measurement, the dynamic test, the field alignment measurement as well as the finite element analysis(FEA) of the second longest rail transit cable-stayed bridge in the world were carried out.Based on the results, the train dynamic load effect on the bridge alignment was obtained quantitatively. Subsequently, alignment control of the rail transit bridge with considering this effect using a self-adaptive Kalman filter method was analyzed. The results show that:(a) the dynamic train loads have effects on alignment control of the bridge and therefore cannot be neglected;(b) the self-adaptive Kalman filter method is applicable and reliable for alignment control of bridges during construction. The analytical method and whole process contribute to develop a related specification and further engineering applications.