我国票据时效问题研究

国际贸易的不断发展使得票据的使用范围超出了一国的地域,成为国际贸易中的信用工具和结算工具,因此,各国票据法对票据制度的规定应该趋于同一。然而对比我国票据法与国际上普遍适用的日内瓦统一票据法,不难发现二者关于票据时效的规定存在多处区别,如时效性质、时效期间、追索权时效的起算点等规定均不同,通过对这些差异进行分析,便会发现我国票据法关于票据时效的规定还有待进一步完善。

随机序与寿命分布类

各种各样的随机序是随机比较方法的最基本的概念。每一种新的、有实际背景和理论依据的随机序的引入都会丰富随机比较方法的研究内容,也有可能使人们更好洞察和理解其中某些概念和结果的本质。而反映时效性质的寿命分布类的研究不仅是随机比较方法的重要组成部分,而且它在运筹学、应用概率和统计学中有广泛的应用。各种寿命分布类的定义密切联系于各种不同的随机序,而且人们还可以反过来从寿命分布类出发定义新的随机序,由此又能引入新的寿命分布类。本文拟将近年这两方面的研究内容和结果作一概括的介绍。

Effect of heat transfer space non-uniformity of combustion chamber components on in-cylinder soot emission formation in diesel engine

Combustion chamber components （cylinder head, cylinder liner, piston assembly and oil film） are treated as a coupled body. Based on the three-dimensional numerical simulation of heat transfer of the coupled body, a coupled three-dimensional calculation model for the in-cylinder working process and the combustion chamber components was built with domain decomposition and boundary coupling method, in which the coupled three-dimensional simulation of in-cylindcr working process and the combustion chamber components was adopted. The simulation was applied in the influence investigation of the space non-uniformity in heat transfer among combustion chamber components on the generation of in-cylinder emissions. The results show that the space non-uniformity in heat transfer among the combustion chamber components has great influence on the generation of in-cylinder NOx emissions. The heat transfer space non-uniformity of combustion chamber components has little effect on soot formation, and far less effect on soot formation than on NOx. Under two situations of different wall temperature distributions, the soot in cylinder is different by 1.3% when exhaust valves are open.