软件需求分析是软件工程的重要一环。现有软件需求分析方法还没有在避免由于使用自然语言可能产生的二义性和避免仅使用一般人不易理解的软件需求分析工具上令人满意。为此,利用自然语言和必要的图形实现了二者的兼顾。该方法适用于需求获取和早期需求分析,也能与其它建模工具一起使用。

随着计算机技术以及网络信息技术的高速发展,各部门都利用互联网建立自己的信息系统,以充分利用各类信息资源.但在连接信息能力、流通能力提高的同时,基于网络连接的安全问题也日益突出.

As more and more PC clusters are used in many factories,the refrigeration system is very important for the performance effect of PC clusters.So more and more attention is being paid to the design and optimization of the refrigeration system.This paper tries to effectively solve the problem of the great difficulty and high cost of the design and optimization of the refrigeration system of the PC cluster room.By means of their practical experience,regrigeration theory and aerodynamics theory,the authors have designed and optimized the refrigeration system of the PC cluster room and received fruitful result after putting it into use.The design method and experience of optimization of the refrigeration system in this paper are fit for the PC cluster rooms and other computer room and of significance for larger PC Cluster rooms.