变形方式对含ZrC粒子20Mn2钢晶粒细化的影响

研究了恒温压缩与降温轧制对含ZrC粒子20Mn2钢晶粒细化的影响.结果表明,在奥氏体再结晶温度区间(1150℃、1050℃)和形变诱导铁素体相变温度区间(950℃、900℃、870℃、850℃),20Mn2钢的晶粒尺寸均能细化至3～4μm;在1150～870℃的降温轧制中,20Mn2钢的晶粒尺寸细化至1～3μm.分析表明,由于ZrC粒子的形变核心和再结晶核心的作用,含ZrC粒子的20Mn2钢在高温下(1150℃、1050℃)和较低温度下(950℃、900℃、870℃、850℃),变形的晶粒组织分别因奥氏体再结晶和形变诱导铁素体相变及其再结晶而得到细化;在降温轧制时,由于综合了高温奥氏体再结晶和低温形变诱导铁素体相变及其再结晶的细化晶粒效应,而最终获得的晶粒尺寸比恒温变形的更小.     

A new numerical method on American option pricing

Mathematically, the Black-Scholes model of American option pricing is a free boundary problem of partial differential equation. It is well known that this model is a nonlinear problem, and it has no closed form solution. We can only obtain an approximate solution by numerical method, but the precision and stability are hard to control, because the singularity at the exercise boundary near expiration date has a great effect on precision and stability for numerical method. We propose a new numerical method, FDA method, to solve the American option pricing problem, which combines advantages the Semi-Analytical Method and the Front-Fixed Difference Method. Using the FDA method overcomes the difficulty resulting from the singularity at the terminal of optimal exercise boundary. A large amount of calculation shows that the FDA method is more accurate and stable than other numerical methods.     

Recent development in computational complexity characterization of Nash equilibrium

The computation of Nash equilibria has been a problem that spanned half a century that has attracted Economists, Operations Researchers, and most recently, Computer Scientists. The study of its complexity, in particular that of the two-player game, has come to a conclusion recently. It is, however, impossible without the subsuming ideas from important progresses made in the various fronts of its investigation. In this article, we present a review of the most relevant ideas, methods, and results in a way that would lead interested readers to get a full picture of the subject. We will also discuss some new issues opened up by the characterization of complexity for the two-player Nash equilibrium problem.     

浅谈锅内水处理

水是锅炉的工作介质,锅炉的水质对锅炉安全运行和节能有很大影响,本文介绍锅炉产生水垢的原因,说明锅内水处理的重要性,以及常用的水处理方法。     

改善室内空气品质的探讨

分析了影响室内空气品质的室内因素及室外因素,指出了传统空调在改善室内空气品质方面存在的问题,最后提出了改善室内空气品质的措施。     

基于国产龙芯GS321的小系统的硬件设计

针对目前在嵌入式领域使用国产芯片比较少的现状，简要介绍了国产32位处理器龙芯2号GS32I的工作原理，着重从硬件方面介绍了其接口的扩展方法和扩展信号的定义，同时给出了基于GS32I小系统的硬件设计方案。     

真空伏辊气流噪声与其结构关系的研究

真空伏辊产生的噪声是造纸车间的主要噪声源。对产生空气动力性噪声的真空伏辊所产生噪声进行了研究与分析，结果表明：产生真空伏辊噪声的原因主要来自：空气流高速穿入小孔所造成的主振荡；沿伏辊旋转方向空气流的振荡。因此，本推导了主噪声与伏辊几何尺寸的相关数学模型，其结果可为进一步研究低噪声造纸机设备提供理论依据。