Modeling Temperature in Coupled Electrical and Thermal Simulations of the Electroconsolidation® Process

Electroconsolidation® is a process for densifying complex-shaped parts by using electrically conductive particulate solids as a pressure-transmitting medium. The part is immersed in a bed of the particulate medium contained in a die chamber. Sintering temperature is achieved by resistive heating of the medium while applying compaction pressure. The process is capable of ultrahigh temperatures and short cycle times and offers the potential for low processing costs.

Control of the process and selection of process conditions require knowledge of the temperatures within the die. Temperature gradients exist because of the high heating rate and because of variations of density and electrical resistivity of the medium due to the presence of the part. Direct measurement of temperature with thermocouples or other conventional means is impractical because of the high temperatures, high currents, and high pressures that are involved. Therefore, a computer model was developed to predict temperature as a function of time and applied voltage for any location in the die. The computer model is composed of three parts: a geometrical model to approximate the density and resistivity variations in the medium, a finite-element model to calculate the rate of resistive heating within each element, and a finite-difference model to calculate the temperature distribution based on solution of the heat-transfer equations. Predicted temperatures have been shown to be in excellent agreement with measurements, and numerical simulation provided encouraging consistency and reasonably accurate predictions of temperature profiles within the die. The model demonstrated the feasibility of a new process to achieve simultaneous application of pressure and heat to powder densification in Electroconsolidation.     

用RPGMaker建立C语言思维模式的方法研究

探讨了在C语言程序设计教学过程中为学生建立相应的思维模式的方法问题。针对非计算机专业学生基础差、专业性不强的特点,结合当前DIY的潮流,分析了C语言的基本结构,分析了RPGMaker中提供的技术可行性,提出通过促进学生使用RPG-Maker软件来制作游戏以建立相应的程序设计思维模式的方法,并提出具体案例供参考。实践表明,学生的程序设计思维能较快速、熟练地建立起来。     

宽频介电谱仪热激励去极化电流功能研究

利用宽频介电谱仪拓展热激励去极化电流模块测量介质材料的TSDC操作简单实用,它不仅容易把材料中的各种不同活化能或弛豫时间的荷电粒子区分开,并且能从TSDC谱中直接得出被测材料的介电性能以及相关微观参数,这为研究材料内部机理提供了一条捷径。     

开关电源模块的几种典型应用

本文中给出了开关电源模块几种典型应用电路，并简单介绍了它们的工作原理。     

产品试制流程的对象化设计方法

以机电产品为例,提出了产品试制流程的对象化方法,包括流程模块分解、对象化设计、层次服务定义等.     

基于IPM器件的电动车驱动系统

IPM器件是日本三菱公司生产的一种基于先进的IGBT技术的功率器件。本文简要介绍了IPM器件的组成、主要特性以及在电动车驱动系统中的应用。     

基于LTCC多层基板技术的宽带T/R组件设计

介绍了一种基于低温共烧陶瓷(LTCC)多层基板工艺的宽带发射/接收(T/R)组件的设计,详细论述了组件的电路布局和装配工艺,给出了具体的测试数据。T/R组件的体积为65mm×29mm×9mm,连续波输出功率大于25W,均方根移相误差小于3°,已达到工程应用要求。     

硅基多层布线集成组装技术

本文叙述了多芯片组件和多层布线集成组装技术的研究和进展,介绍了硅基多层布线集成组装技术的特点和设计考虑,扼要地叙述了硅基多层布线的制造工艺,并讨论了工艺中所出现的问题。     

基于并播技术的DVB发送卡设计

介绍了并行广播技术,提出了作为大规模信源的并行数据如何通过MPEG-2传输流数据发送卡实现这种海量传输的硬件实现方案,并分析了设计要点.     

WDM光传输系统2.5Gbit／s光发送模块研究

本文介绍了作者设计，调试的２．５Ｇｂｉｔ／ｓ光发送模块的工作原理、关键技术、典型性能参数，该模块通过控制激光器温度来稳定其中心波长，为波分复用系统的应用提供了具备稳定中心波长特性的光源。