电容放电式长延时电路

本文介绍一种利用电容放电获取长延时的方法，通过实用电路，叙述了其工作原理。

关于三相交流异步电动机启动控制电路设计的分析

三相交流异步电动机在日常生活中广泛使用。要求对其安全、可靠、自如控制。在现代电工,尤其是PLC可编程控制器中,电动机"启-保-停"控制电路是其设计中的基本。本文循序渐进就三相交流异步电动机启动控制电路设计的过程,做了优缺点的分析,以便使用三相交流异步电动机的人能清楚理解并掌握其设计原理及过程。

Epitaxial Growth of 150mm Silicon Epi\|Wafers for Advanced IC Applications

With the device feature's size miniaturization in very large scale integrated circuit and ultralarge scale integrated circuit towards the sub\|micron and beyond level, the next generation of IC device requires silicon wafers with more improved electrical characteristics and reliability as well as a high perfection of the wafer surface. Compared with the polished wafer with a relatively high density of crystal originated defects (e. g. COPs), silicon epi\|wafers can meet such high requirements. The current development of researches on the 150mm silicon epi\|wafers for advanced IC applications is described. The P/P\++ CMOS silicon epi\|wafers were fabricated on a PE2061 Epitaxial Reactor (made by Italian LPE Company). The material parameters of epi\|wafers, such as epi\|defects, uniformity of thickness and resistivity, transition width, and minority carrier generation lifetime for epi\|layer were characterized in detail. It is demonstrated that the 150mm silicon epi\|wafers on PE2061 can meet the stringent requirements for the advanced IC applications.

Recursive bisection placement algorithm with the predicted wirelength

To obtain a better placement result, a partitioning-based placement algorithm with wirelength prediction called HJ-Pl is presented. A new method is proposed to estimate proximity of interconnects in a netlist, which is capable of predicting not only short interconnects but long interconnects accurately. The predicted wirelength is embedded into the partitioning tool of bisection-based global placement, which can guide our placement towards a solution with shorter interconnects. In addition, the timing objective can be handled within the algorithm by minimizing the critical path delay. Experimental results show that, compared to Capol0. 5, mPL6, and NTUplace, HJ-P1 outperforms these placers in terms of wirelength and run time. The improvements in terms of average wirelength over Capo10. 5, mPL6 and NPUplace are 13%, 3%, and 9% with only 19%, 91%, and 99% of their runtime, respectively. By integrating the predicted wirelength-driven clustering into Capo10. 5, the placer is able to reduce average wirelength by 3%. The timing-driven HJ-P1 can reduce the critical path delay by 23%.

Transmission line realization of subwavelength resonator formed by a pair of conventional and LHM slabs

In this paper, the authors present the transmission line (TL) realization of one-dimensional subwavelength resonator formed by a pair of conventional right-handed material (RHM) and left-handed material (LHM). In such resonator, a novel reso- nant mode with the resonant frequency depending on the length ratio of the RH/LH TL sections occurs as a consequence of the full phase compensation due to the backward wave in the LH TL section. The theoretical circuit-model analyses are supported by simulation and experimental evidence on resonators with different RH/LH length ratios.

Study in the design and manufacture process of the elastic cable anchor box in steel box girder of Taizhou Bridge

Taizhou Yangtze River Highway Bridge is a large span suspension bridge with three pylons. The elastic cables are installed to connect the steel tower and the steel box girder. The constraints can increase the safety coefficient of the middle saddle, and improve the stress conditions of the middle pylon and decrease the deflection in the middle of the main girder, as well as the longitudinal displacement of the main girder caused by live loads. The anchorage boxes of the elastic cable are installed in the wind fairing outside the vertical web plate of the box girder. Two anchor boxes form a pair and are arranged parallelly. Eight anchor boxes are installed in the bridge. In this paper, the design scheme and the technical difficulties in manufacturing are briefly discussed with the precision control techniques.

Energy conservation research of dehumidification system for main cable anticorrosion of suspension bridge

The necessity of the main cable anticorrosion for suspension bridge is described, and operating principles and composition of main cable dehumidification system are analyzed. An idea using the waste heat of high temperature outlet air of dehumidification system to heat up regeneration air of rotary-type dehumidifier is put forward in this paper. The concrete scheme is to install a heat exchanger on air-out pipeline of roots blower and air-in pipeline of regeneration electric heater of rotary dehumidifier. Air preheated by the heat exchanger enters regeneration electric heater of rotary-type dehumidifier. Energy conservation of main cable dehumidification system for the Yangtze River highway bridge is calculated, and the results show that energy conservation rate can reach 44 %.

Frequency Variations of Power System Due to Switching of Renewable Energy Sources

Power systems in Germany mainly containing intermittently operating renewable sources require load/frequency control which is performed up to now at the AC transmissioh and distribution levels. Frequency control can be achieved by employing short-and long-term storage plants buffering and complementing renewable energy sources. A representative grid consists of a natural-gas-fired plant serving as frequency leader, long-term storage plant, wind-power farm with associated short-term storage plantfor energy buffering, and photovoltaic farm with associated short-term storage plant interconnected by a long transmission line to two load circuits. Transient analysis is performed with Mathemafica solving the differential equation system for frequency variation. Powerflow through the AC transmission line is limited by its impedance. The long transmission line must be segmented to achieve stability and voltage control over an 800 km distance. The renewable plants must be operated together with the storage plants in order tominimize frequency variations by smoothing the power output of renewable plants, achieving step-wise control of the transmission-line power. Although to date only AC Iransmission lines in Germany exist, it is anticipated that within the next 10 years these will beaugmented by DC high-voltage lines.

A Study on an Airgap Control System in a Rotary-Small-Scaled Linear Induction Motor for Railway Vehicles

In general, it is important to operate the; airgap length uniformly for improving the system efficiency independent of the flatness of the reaction plate in a railway propulsion system by a linear induction motor （LIM）. And it is possible to operate the LIM propulsion system efficiently without a change of the LIM capacity through the airgap length control on the sloped rail. So, in this research, the authors introduce an airgap control system to control the airgap length which depends on the flatness of the secondary reaction plate when the LIM is operated, and design a rotary small-scaled LIM and its airgap control system before manufacturing the real system. Then, the authors analyze some characteristics of the LIM （thrust and normal force, input current, efficiency and power factor）, and through the LIM control modeling, the authors finally analyze an effect of the airgap-length control of the LIM by the airgap control system.

GaN PIN betavoltaic nuclear batteries

GaN PIN betavoltaic nuclear batteries are demonstrated in this work. GaN epitaxial layers were grown on 2-inch sapphire sub-strates by MOCVD, and then the GaN PIN nuclear batteries were fabricated. Current-voltage （l-V） characteristic shows that the small leakage currents are 0.12 nA at 0 V and 1.76 nA at -10 V, respectively. With 147Pm the irradiation source, the maximum open circuit voltage and maximum short circuit current are 1.07 V and 0.554 nA, respectively. The fill factor （FF） of 24.7% for the battery was been obtained. The limited performance of the devices is mainly due to the low energy deposition in the microbatteries. Therefore, the GaN nuclear microbatteries are expected to be optimized by growing high quality GaN films, thin dead layer and so on.