Residual stress magnitudes and related properties in quenched aluminium alloys

Abstract

The surface and through thickness residual stress magnitudes present in heat treated high strength aluminium alloy components are frequently reported to exceed the uniaxial yield stress of small specimens of the same alloy measured immediately after quenching. In thick section plate and forgings, it is proposed that these high residual stress magnitudes are a consequence of hardening precipitation that occurs during quenching which allows a greater elastic stress to be supported. To investigate this theory, a Jominy end quench technique is used to determine the hardness of aluminium alloys 7010, 7175 and 5083 as a function of distance from the quenched end. Cooling curves have been measured for Jominy end quench specimens using deeply buried thermocouples and are compared with finite element model predictions. Tensile properties are also determined for small specimens quenched into cold and boiling water. Vickers hardness and X-ray diffraction residual stress measurements are undertaken on specimens of varying size acting as a comparison with the Jominy results. These results in combination with optical and electron microscopy data do suggest that low temperature rather than high temperature precipitation during the quench leads to increased as quenched mechanical strengths, with the consequence that less quench sensitive alloys will support higher residual stress magnitudes as section thicknesses increase.     

Simulated effects of martensite start temperature,thermal conductivity and pore content on end quench cooling rate

Abstract

Process modelling, based on finite difference methods, is used to show that the thermal conductivity increases, which typically attend the martensite transformation in steel, affect the cooling rate in the Jominy end quench test. A one-dimensional model, which includes the effects of material property variations, is presented that predicts slightly increased cooling rates with increases in the M _s temperature for fully dense steels and significantly increased rates for powder metallurgy (PM) steels. The model is based on earlier studies of the end quench test that initially showed increased cooling rates in PM steels versus fully dense ones and then went on to show water penetration of the pores as a causative mechanism. In the present study, it is shown that by combining a simple theory of this mechanism with the aforementioned M _s effects, it is possible to obtain cooling curves that display a marked resemblance to the experimentally observed ones of these earlier studies.     

VxWorks环境下BAN交换机驱动程序的设计与实现

VxWorks是一种实时的嵌入式操作系统，它的模块化设计使得应用代码与硬件充分隔器，为应用程序的移植提供了方便，本文主要从VxWorks环境下数据链路层和网络层结构的模型入手，根据我们自行研制的小区交换机的实际情况，详细阐述了BAN交换机驱动程序的设计思想以及系统函数和任务函数的实现过程。     

VxWorks增强型网络驱动程序（END）的分析与实现*

随着嵌入式操作系统VxWorks在国内外各种领域越来越广泛的应用,如何让VxWorks支持各种硬件平台成了亟待解决的问题。介绍了设备驱动相关的一些基础知识,阐述如何在VxWorks中添加END驱动,最后对Wind River提供的END网卡驱动程序模板进行流程上的分析。     

一种vxWorks下网卡快速切换的实现方法

介绍了一种在vxWorks操作系统驱动层实现冗余网卡链路检测与快速切换的方法（虚拟网卡），详细阐述了实现的方法及实现中注意的一些问题。采用该方法可以快速、无缝地进行链路切换，更为有效地保证数据传输的可靠性。     

基于MPC8260的ATM驱动开发

介绍了ATM技术的特点以及深入分析了P0werPC MPC8260的ATM步长控制器(APC)的原理．分析了VxWorks网络模块，给出了在VxWorks实时操作系统下的END模式的ATM驱动程序设计，重点讨论了ATM驱动开发中需注意的特殊问题。     

基于VxWorks的网络增强型驱动分析与实现

网络驱动的开发是基于VxWorks的嵌入式应用的重要组成部分;VxWorks提供了多路复用层(MUX)接口来实现增强型网络驱动(END)的开发,具有协议无关性特点,可使开发人员专注于驱动程序的开发而无需考虑上层协议的内容,利用这种方法对RTL8139网卡的END开发进行了研究;首先阐述了END的数据结构和接口函数,然后着重分析了BSP中相关文件的配置,最后对驱动的加载启动过程及数据包的存储收发过程作了介绍;对于VxWorks下基于MUX机制的其它网卡驱动的开发具有参考价值。     

VxWorks实时操作系统下MPC8260ATM驱动的实现

本文介绍了PowerPCMPC8260工作在ATM模式的原理,给出了在VxWorks实时操作系统下的END模式的ATM驱动程序设计及实现,实验证实该驱动通过Mux层在IP层与链路层之间建立了数据传输通道。     

基于VxWorks的DM9000网卡驱动

随着嵌入式操作系统VxWorks的广泛应用,如何让VxWorks支持各种硬件平台成了急需解决的问题。首先介绍大幅面扫描仪的发展趋势以及嵌入式操作系统VxWorks的优势。然后通过分析VxWorks的SENS协议栈;VxWorks下END网络驱动程序的结构;S3C2440A板载DM9000网卡的硬件特性和操作特点,实现基于VxWorks的DM9000 END驱动程序。最后修改相应bsp,使S3C2440A可以跨平台通信。     

The sequence of a 17 933 bp segment of Saccharomyces cerevisiae chromosome XIV contains the RHO2, TOP2, MKT1 and END3 genes and five new open reading frames

We report the DNA sequence of a 17 933 bp fragment from the left arm of chromosome XIV of Saccharomyces cerevisiae. Analysis of the sequence reveals the presence of ten open reading frames (ORFs) larger than 100 codons. Four of these were previously identified as genes RHO2, TOP2, MKT1 and END3. Additionally, the NH₂ end coding region of PMS1 is found in the 3′ end of the sequence. No significant homology to any known protein has been found for the other five ORFs. The nucleotide sequence has been deposited at EMBL, with Accession Number X89016.