支架零件半固态压铸充型过程的模拟和验证

利用AnyCasting软件模拟了支架零件的半固态压铸充型过程,对比分析了不同的充型速度、转换位置对充型结果的影响,并进行了试验验证。结果表明,当压射冲头以0.1m/s低速推动半固态浆料通过内浇道,在充型20%进行1m/s高速转换时,能够获得完整、轮廓清晰的半固态成形件。模拟结果与实际相符合。     

数控转塔冲床上下料助力机械手设计与分析

根据数控转塔冲床的特点以及生产现场实际,分析了助力机械手在数控转塔冲床板料上下料的应用,构建了板料抓取结构、助力机械手、数控转塔冲床的组成单元,设计了拆垛上料机机械本体的整体机构,并介绍了关键技术有限元分析和运动学分析。     

置换反应热测定实验的研究

文章介绍了锌置换硫酸铜反应热测定的方法,比较了两种不同操作对结果的影响和产生原因。文中利用Origin软件处理实验数据,绘制了反应时间与温度的变化曲线,应用外推法计算系统温度的变化情况。实验改进后节省了宝贵实验时间,学生有余力围绕基础实验进行探索性研究,提高了教学质量。     

大规模AHF装置特点及设计需考虑的问题

叙述了国外AHF大规模装置主要特点及主要AHF技术拥有者采用的主要技术,对照了原料消耗与质量情况。探讨了国内设计AHF大规模装置需考虑的问题,并提出了建议。     

螺栓法兰紧固的结构优化

为提高压力容器螺栓法兰的紧固效果,对液压扳手和握持套筒的结构进行了改进,优化了握持套筒,并设计了一款新型固定扳手;对螺栓法兰紧固操作的液压扳手和握持套筒的配合使用进行了详细介绍并进行了对比,对握持套筒存在的问题进行了改进;运用ANSYS对新型固定扳手进行了静力学结构分析。结果表明,该结构优化可有效提高压力容器法兰螺栓的紧固效果。     

DM642在网络视频传输系统中的应用

数字信号处理器TMS320DM642在多媒体通信领域有着广泛的应用。以利用XDAIS算法在DM642上实现网络视频编码器为例，研究了DM642在网络视频传输系统开发中的一般过程，介绍了系统的硬件和软件模块的功能、工作原理和RP5在程序中的使用方法，并详细分析了使用NDK进行网络功能开发的过程。实践证明，所用方法是正确有效的。该系统模型可作为网络视频监控系统的一个通用平台。     

Reliability Analysis of Phased-Mission System With Independent Component Repairs

This paper proposes a hierarchical modeling approach for the reliability analysis of phased-mission systems with repairable components. The components at the lower level are described by continuous time Markov chains which allow complex component failure/repair behaviors to be modeled. At the upper level, there is a combinatorial model whose structure function is represented by a binary decision diagram (BDD). Two BDD ordering strategies, and consequently two evaluation algorithms, are proposed to compute the phased-mission system (PMS) reliability based on Markov models for components, and a BDD representation of system structure function. The performance of the two evaluation algorithms is compared. One algorithm generates a smaller BDD, while the other has shorter execution time. Several examples, and experiments are presented in the paper to illustrate the application, and the advantages of our approach.     

First Cycle Effect of Polycrystalline CuZnAl Shape Memory Alloy during Thermal-Mechanical Cycling

The thermal-mechanical (T-M) cycles at constant strain of a polycrystalline CuZnAl alloy have beenstudied in the. present work. In-situ optical microscopic observations have been made to reveal thefeatures of the phase transitions during T-M cycling. The variation of stress-temperature (S-T)curves and electrical resistance-temperature (R-T) curves accompanying with T-M cycling havebeen measured by tensile test and electrical resistance measurements. It has been found that thepolycrystalline CuZnAl alloy shows apparent morphology changes and properties variations in thefirst cycle during T-M cycling which is called the first cycle effect in the present work. The stabletransformation procedure in the T-M cycle is: martensiteparent phase +residual acicularmartensite. This residual martensite possesses the character of stress-induced martensite.     

各向异性压电陶瓷研究的新进展

本文叙述了几种新型的机电耦合各向异性的压电陶瓷，对各向异性的机理和应用前景作了简单的分析。     

The netlike inference process and stability analysis

In this article, an inference process is defined as a series of events in which the truth values flow from propositions along certain inference channels. the concepts of netlike inference process and solution searching process are then described. the notion of excitedness is defined as a measure of the activeness of thinking. In the context of an inference process, excitedness describes the truth of the proposition or the belief in the proposition. While in a solution searching process, excitedness describes the ability and/or desire to solve the problem. By introducing simple flows and their network graphs, the process of excitedness flows on the network is described be a set of differential equations with steady state solutions and stability analysis performed by applying Markov process theory. By introducing the concepts of complex flows and multi-branch graphs, the process of excitedness flows on the graph is also described by a set of differential equations with steady state solutions and stability analysis performed similar to Prigogine's theory of dissipative structures.¹ Finally, the idea of using computers in netlike inference is proposed.