Investigation on hot deformation behavior and mathematical models of flow stress of high-strength structural steel

The effect of deformation conditions on dynamic recrystallization behavior of Nb,V,Ti microalloyed high-strength structural steel was investigated via high-temperature single pass reduction tests on a MMS-300 thermomechanical simulator,with mathematical models established for flow stress during hot deformation.The results show that the deformation resistance decreases with the increase of temperature and is in power function relationship with the temperature.Meanwhile,it increases with the increase of st...     

UPS电源的现状、发展及选配

本文主要叙述UPS电源在技术上、管理体系上、设计原理上,以及功能和应用方面的现状及未来的发展趋势,并对用户如何选配UPS电源作了详细论述。希望能对广大用户认识和配置UPS电源起到一定的指导作用。     

整流后滤波用电解电容的选择

整流滤波用电解电容器容值的改变不仅影响输出电压,还会影响电容本身的纹波电流,进而对损耗和电容本身的寿命带来影响。本文建立了滤波电容纹波电流的数学模型,利用Saber仿真结果和计算结果对比验证了模型的正确性。基于所建立的数学模型分析了容值变化对纹波电流和电容损耗的影响,进一步完善了滤波电容的选取依据。     

基于UC1901的行波管灯丝电源的设计

讨论了UC1901芯片在行波管灯丝电源中的应用,给出了所涉及的重要参数设计准则和设计方法,并采用该芯片实现了稳压灯丝电源。     

单端变换器在行波管电源中的应用

分析了一种单端正激变换器的衍生电路,给出它的优缺点,结合行波管电源的要求,对电路进行了试验,给出相关试验波形。     

第三届长江论坛及长江-欧盟高层对话会

第三届长江论坛将于2009年4月19日至21日在上海举行,论坛由上海市人民政府和长江水利委员会主办,中国-欧盟流域管理项目、世界自然基金会和美国大自然保护协会协办。     

油膜振荡下转子疲劳的损伤力学研究

在对油膜振荡进行非线性动力学分析的基础上,将其动力学响应作为位移边界条件,把损伤引入到材料的本构关系当中,考虑损伤与应力、应变的相互影响,采用全耦合的损伤力学分析方法对转子在油膜振荡行为下的损伤发展过程进行了分析,揭示了转子在油膜振荡行为下的疲劳破坏机制;同时分析了损伤与应力、应变的耦合作用对损伤演化、发展的影响,为汽轮机组的灾变防治和安全设计提供了一定的理论依据。     

蒙特卡罗程序TRIPOLI自动建模方法研究

TRIPOLI是法国原子能署(CEA)开发的三维蒙特卡罗粒子输运计算程序,在反应堆物理分析、辐射防护设计、核安全评估等领域得到广泛应用。但是手工描述其输入文件耗时,容易出错,质量得不到保证。本文研究了TRIPOLI自动建模方法,实现了CAD工程模型与TRIPOLI模型的相互转换。通过对基准例题的计算分析,证明了其转换结果正确、可靠。     

Lithium coatings on NSTX plasma facing components and its effects on boundary control, core plasma performance, and operation

NSTX high power divertor plasma experiments have used in succession lithium pellet injection (LPI), evaporated lithium, and injected lithium powder to apply lithium coatings to graphite plasma facing components. In 2005, following the wall conditioning and LPI, discharges exhibited edge density reduction and performance improvements. Since 2006, first one, and now two lithium evaporators have been used routinely to evaporate lithium onto the lower divertor region at total rates of 10-70 mg/min for periods 5-10 min between discharges. Prior to each discharge, the evaporators are withdrawn behind shutters. Significant improvements in the performance of NBI heated divertor discharges resulting from these lithium depositions were observed. These evaporators are now used for more than 80% of NSTX discharges. Initial work with injecting fine lithium powder into the edge of NBI heated deuterium discharges yielded comparable changes in performance. Several operational issues encountered with lithium wall conditions, and the special procedures needed for vessel entry are discussed. The next step in this work is installation of a liquid lithium divertor surface on the outer part of the lower divertor.     

Properties of vacuum-deposited Li films and impact on plasma performance in TJ-II

Drastic changes in the operation of the Spanish TJ-II stellarator have been produced upon lithiation of its first wall in 2007, performed by direct vacuum evaporation. From the operational point of view, much more stable, reproducible plasmas have been achieved, mostly due to the excellent density control associated with the low recycling wall characteristics. It has allowed exploring new, high densities, high power plasma conditions never attained under the previous, boron coating scenarios. In addition to this, new physical phenomena arose. Thus, for example, clear transitions to enhanced confinement modes (H mode) and strongly peaked plasma profiles were observed under the new wall conditions. In this paper, a summary of the main findings is described, and recent results on the interchange of plasma species (H vs. He) and sputtering in the Li wall are described and discussed.