逆变式电阻焊机的研究进展

介绍了逆变电阻点焊机的特点,国内外逆变点焊机的研究现状,提出了逆变点焊电源研制过程中存在的几个问题。     

风力机新系列翼型气动性能研究

风力机翼型气动性能是风力机气动设计和性能分析的重要基础。采用粘性和无粘性结合的分析计算方法，对风力机新系列翼型进行了气动性能研究，用低雷诺数翼型分析和设计软件XFOIL分析了FFA－W3系列两种翼型在不同雷诺数和不同马赫数下的气动性能，并与实验数据进行了比较，取得了比较一致的结果。     

几何激波动力学在激波绕射反射和聚焦中的应用

本文考虑激波面的运动而不计其波后流场的影响，利用Ｗｈｉｔｈａｍ的几何激波动力学理论，建立了一个简单的在时间上为二阶精度的显式二步蛙跳数值计算格式，计算了激波的绕射、反射和聚焦问题。计算结果表明，该方法简便易行，而且被面形状在计算中自动产生。     

两种氧枪喷头射流行为的数值模拟

对80 t转炉四孔氧枪进行实验室的数值模拟研究,通过对比两种不同参数的氧枪射流以及对熔池的作用效果,得出OL-M2氧枪比OL-M1氧枪的最大射流半径提高6.7%,冲击深度降低4.5%,熔池作用面积提高3.3%。为保证氧枪能处于良好的作用条件,给出了氧枪合理的操作压力和枪位控制区间。通过对熔池混匀时间的模拟,得出OL-M2氧枪下的平均混匀时间比OL-M1氧枪下的混匀时间缩短48 s,使用OL-M2氧枪相比使用OL-M1氧枪对熔池的搅拌效果更好,这有利于促进冶炼前期脱磷反应的传质进行。     

MQ75140/X型龙门磨铣床浅析

用户对机床的需求越来越多样化,MQ75140/X磨铣床就是根据用户需求开发的新型机床,现对该机床的结构、原理及发展前景进行介绍。     

The numerical modeling of acoustic wave propagation using the multiple pressure variables approach

Based on an asymptotic analysis of the compressible Navier–Stokes equations, the basic concept of the Multiple Pressure Variables (MPV) approach is to split up the pressure into three different terms representing global background effects, acoustic waves and the incompressible pressure, respectively. Special attention is payed to aeroacoustic phenomena and the numerical treatment of the generation and spreading of sound waves. To this aim, further perturbation analysis is done about the incompressible limit solution. This gives hints how to extract acoustic waves responsible for the noise generation from the flow field.This work has been supported by Deutsche Forschungsgemeinschaft (DFG).     

A study of parameter-free shock capturing upwind schemes on low speeds’ issues

Nowadays,the upwind schemes are in a rapid development to capture shock accurately.However,these upwind schemes’properties at low speeds,such as their reconstruction scheme dependencies,grid dependencies,and Mach number dependencies,are concerned by few people.In this paper,a systematic study on their low speeds’issues is conducted.Through a series of tests,we can find that most parameter-free upwind schemes,widely used in practice today,are not applicable to low speeds’simulations.In contrast,SLAU and SLAU2 can give reliable results.Also,the upwind scheme’s influence on the accuracy is stronger than the reconstruction scheme’s influence at low speeds.     

微内核操作系统设计方法及其实例的比较

微内核操作系统提供了并行计算机所需的功能和性能,是并行操作系统的发展方向讨论微内核操作系统的基本设计方法,并介绍几个典型实例：Ａｍｏｅｂａ,Ｍａｃｈ,Ｃｈｏｒｕｓ．     

User-level Real-Time Network System on Microkernel-based Operating Systems

This paper presents the design and implementation of a user-level real-time network system in Real-Time Mach. Traditional network systems for microkernel based operating systems, which tend to focus on high performance and flexibility, are not suitable for real-time communication. Our network system provides a framework for implementing real-time network protocols which require to bound protocol processing time, and it is suitable for implementing on microkernel based operating systems. In this paper, we especially focus on the aspects to avoid the priority inversion problem in order to make network systems more preemptable and predictable. We also describe the feasibility of our network system for building distributed multimedia systems.     

类乘波飞行器进气道/隔离段数值仿真研究

采用二维耦合隐式NS方程和标准kε湍流模型对超燃冲压发动机进气道/隔离段进行了数值仿真研究,分析了隔离段出口反压、长高比以及进气道入口马赫数对进气道出口性能参数的影响,发现反压对进气道出口参数影响很小;长高比对进气道出口上下壁面处静压影响较大,但对出口处马赫数及静温影响很小;进气道入口马赫数的变化对出口上下壁面处静压影响剧烈,且随着入口马赫数的增加,进气道出口马赫数和静温均增加,入口马赫数越低,进入隔离段内的气流越均匀.