An overview of the welding technologies of CLAM steels for fusion application

China Low Activation Martensitic steel (CLAMs), a kind of RAFM steel with Chinese intellectual property rights, is considered as the primary structural material for the China-designed ITER test blanket module (TBM). As one of the key issues in the fabrication of the fusion reactor, the welding technologies of CLAMs are reviewed. Emphasis is placed on the weldability of CLAMs by different welding methods, and on the properties of as-welded and post-weld heat-treated joints. Recent highlights in research and development for the welding of CLAMs show that proper welding procedure could provide welds with adequate tensile strength but the welds exhibit lower impact toughness compared with the base metal. Post-weld heat treatment (PWHT) and the application of ultrasonic energy during TIG welding could dramatically improve impact toughness. Research also shows that welds in CLAMs have sufficient resistance to swelling under irradiation as well as suitable compatibility with liquid LiPb. The microstructure, mechanical and other physical properties of welds are significantly different from those of the base metal due to the complicated welding thermal cycle. The weld joint is the area most likely to fail one or more of the design requirements within the fusion reactor. Therefore significant additional research is necessary to ensure safe application of welded CLAM steel for fusion reactor construction.     

Sensitivity analysis based preform die shape design for net-shape forging

A sensitivity analysis method for preform die shape design in net-shape forging processes is developed in this paper using the rigid viscoplastic finite element method. The preform die shapes are represented by cubic B-spline curves. The control points or coefficients of B-spline are used as the design variables. The optimization problem is to minimize the zone where the realized and desired final forging shapes do not coincide. The sensitivities of the objective function, nodal coordinates and nodal velocities with respect to the design variables are developed in detail. A procedure for computing the sensitivities of history-dependent functions is presented. The remeshing procedure and the interpolation/transfer of the history-dependent parameters, such as effective strain, are stated. The procedures of sensitivity analysis based preform die design are also described. In addition, a method for the adjustment of the volume loss resulting from the finite element analysis is given in order to make the workpiece volume consistent in each optimization iteration. The method developed in this paper is used to design the preform die shape of H-shaped forging processes, including plane strain and axisymmetric deformations. The results show that a flashless forging with a complete die fill is realized using the optimized preform die shape.     

运用2.4GHz无线技术串连所有装置

随着科技的发达,人们的生活真是越来越舒适了。我们轻松地利用遥控器开启车库大门、电视机、录像机、DVD放映机,我们也能以无线电话、呼叫器、以PDA随时随地进行通讯联络。我们甚至能运用无线技术来监看婴儿房的动静。无线技术已成为生活中不可或缺的一部份,并且被视为理所当然的必须品。还记得必须从沙发上起身去按电视机按钮的日子吗? 现在即使是更换遥控器电池,就会被认为是不方便的事。近年来,我们对无线技术的接纳度已日趋成熟。我们不仅希望使用各种无线装置,更希望这些装置传输速度更快、价格更低廉、并能提供更高的频宽。我们也希望无线装置、家庭剧院系统以及数据网络能具备安全、稳定、以及可靠等特性;并且在彼此紧邻相近时,不会产生相互干扰的现象。而这个趋势将促使现今领先市场的红外线(IR)、27MHz、以及900MHz在内的装置难以继续发展;因此2.4GHz无线技术将取而代之成为市场的主流。     

Calibration control of robot vertical assembly

Calibration methods that apply relative techniques to map robot inaccuracy increase robot flexibility by allowing for greater use and application of off-line path planning techniques. To successfully implement the off-line techniques described in this article, methods have been integrated for off-line tool control frame (TCF) calibration, data base integration, and on-line robot inaccuracy correction. The TCF calibration methods presented in this article successfully determine the TCF origin of the end-effectors and sensors attached to the robot distal link to within the robot repeatability. When the methods were applied to a SEIKO DTRAN RT-3000 robot, the TCP origins were statically predicted correct to within 0.025mm (0.001 in.). On-line methods determine robot inaccuracy by mapping robot configurations relative to operational parts or to spatial templates, in contrast to the contemporary global mapping approaches. For the Seiko robot the resulting inaccuracy distributions permit simple error correction equations to be applied, improving robot positioning accuracy to less than ±0.1 mm in locally large regions and to within the repeatability of the robot ±0.025 mm) in smaller regions. This represents an order-of-magnitude decrease in robot inaccuracy.     

Privacy in the private sphere

This article examines the issue of privacy within the home as a way of exploring the contradiction between feminist views that women and men experience the home differently ‐ and indeed that women may find the home oppressive ‐ and Saunders’ recent (1990) evidence that men and women express similar and equally strong positive sentiments about their home. We conclude that privacy within the home is negotiated within the wider framework of familial ideology and the ideals of ‘home’ and the companionate marriage’, so that within the home there is typically differential access to privacy for adults and children, and men and women.     

无线芯片商的生存之道

过去两年来,消费品市场的供应链出现一系列深刻的结构调整.无线芯片供应商面临一个关键问题:哪些公司将成为蠢笨的巨人,哪些公司能够灵巧地适应新环境并生存下来?