Finite element analysis of a center crack specimen warm pre-stressed under different modes of loading

Load bearing capacity of cracked specimens can be improved following pre-loading procedures like warm pre-stressing (WPS). In this paper, the effects of modes I and II pre-loading on fracture load of a central angled crack specimen are studied by finite element analysis. The specimen is reloaded either in mode I or in mode II. To predict the fracture load of cracked specimen after pre-loading, the maximum tensile stress (MTS) and maximum shear stress (MSS) criteria are used. It is shown that mode II fracture load is independent of pre-loading but the mode I fracture load is highly improved after warm pre-stressing. The mode mixity of the specimen is also changed when the pre-loading and reloading modes are not identical. An increase in the fracture load of the specimen following pre-loading may be due to change of failure mode as predicted by finite element analysis in this work.     

基于T0944的新型平板显示接口卡的设计

介绍了平板显示控制芯片TO944的特点、功能、原理，并给出了基于T0944芯片的新型平板显示接口卡的软硬件实现方案，该方案具有电路简单、高可靠性、高性价比、高显示质量等优点，可用于各种不同类型与不同尺寸的平板显示器的显示。     

刍议C~3I系统技术在城市交通管理中的应用

首先简单叙述了Ｃ３Ｉ系统在军事上的应用，然后针对我国各类大中型城市的交通现状及特点，涉及到城市交通管理、道路管理、车辆管理和城市交通管理指挥中心站、区域指挥站及各交叉路口控制站，提出将Ｃ３Ｉ系统体系结构运用到民用城市交通管理中去的构想。     

131I治疗经ATD治疗后复发甲亢的短期疗效观察

对68例经ATD治疗复发后的甲亢患者，采用以^131I治疗为主的综合性治疗。结果显示，^131I经ATD治疗复发的甲亢疗效理想；及时监测甲状腺激素水平，功能异常时适时达量辅以ATD或甲状腺素制剂很有必要。     

军事卫星通信系统的发展趋势

卫星通信在C~3I系统中将发挥越来越重要的作用,而目前卫星通信又处在一个大发展的时期,可以预计在未来的十年到二十年间卫星通信将面临许多重大变革。论文从四个方面论述了军事卫星通信系统的发展趋势。     

A Survey of Inverse Surface Design From Light Transport Behavior Specification

Inverse surface design problems from light transport behavior specification usually represent extremely complex and costly processes, but their importance is well known. In particular, they are very interesting for lighting and luminaire design, in which it is usually difficult to test design decisions on a physical model in order to avoid costly mistakes. In this survey, we present the main ideas behind these kinds of problems, characterize them, and summarize existing work in the area, revealing problems that remain open and possible areas of further research.     

基于IP视频监控系统云台控制的设计与实现

I2C总线和PCI_XIO是Philips公司最新DSP芯片PNX1302的两个常用接口.文中介绍了采用上述两个接口设计与实现基于IP视频监控系统的云台控制方法以及比较.基于I2C总线的云台控制方法是利用PNX1302 DSP芯片所集成的I2C总线,根据I2C总线的工作原理、传输速率以及云台控制信息比特数少的综合因素考虑实现的.基于PCI_XIO接口的云台控制方法是根据PNX1302 DSP芯片的PCI总线接口为实现8 bit数据传输而特别设计的PCI_XIO接口实现的.     

大功率柴油机连杆三维精细分析

连杆作为柴油机的关键零部件，其刚度和强度对于柴油机的性能和功率的提高起到至关重要的作用。采用MSC／MARC程序及三维多体接触的方法，对G32柴油机连杆的应力场和位移场进行了数值模拟。进而为降低机械负荷、改善应力分布和进一步强化奠定基础。     

Micromechanical modelling of ductile crack growth in the binder phase of WC–Co

This study focuses on numerical simulation of ductile failure in the Co binder phase of WC–Co hardmetal. The growth of edge cracks under mode I loading is considered. A computational micromechanics approach is taken where the Co binder ligaments are explicitly represented in finite element models. An embedding technique is employed. Crystal plasticity theory is used to represent plastic deformation in the Co ligaments. Crack propagation in the binder is simulated using an element removal technique based on a modified Rice and Tracey model for ductile void growth, and fracture resistance curves are generated. Parameter studies are performed for variations in microstructrual parameters such as numbers of Co ligaments ahead of the crack tip and local Co volume fraction. The importance of thermal residual stresses and finite element mesh density are also investigated.     

有限转角无刷力矩电动机位置伺服系统的电流控制

提出了有限转角无刷力矩电动机 (LABLTM)位置伺服系统电流控制策略 ,给出了实施方法 ,进行了开关管频率特性的分析。该方法可实现在不同误差时自动调节电动机电流 ,进而控制输出转矩 ,并具有稳态精度高、动态响应快等特点。