eGiST:一种改进的通用搜索树

新型应用领域的出现,要求数据库系统提供支持数据类型和查询谓词可扩展的索引结构。该文首先介绍了具有这种可扩展性的通用搜索树结构(GiST),分析了GiST在结点溢出处理策略上的不足,并提出了一种改进的通用搜索树结构eGiST,提高了空间利用率和系统效率。     

面向对象技术中标识对象的策略

面向对象（OO）分析模型的核心是对象，如何找出这些对象是OO技术所面临的中心挑战。对标识对象策略的探讨，有助于对OO技术的深入理解和掌握。本文结合需求文档分析工具的对象标识，对相关的问题进行了讨论。     

R6P电池质量事故分析

作者通过解决R6p电池发生的质量事故,阐述了电池质量恶化的形成原因、表现现象并指出了解决电池质量问题的方法。     

子系统闭右半平面传输零点对一般二自由度控制系统闭环传递矩阵的限制

对于一般二自由度控制系统，本文讨论了当系统内稳定时，子系统闭右半平面传输零点对系统闭环传递矩阵的限制．这种限制对于闭环传递矩阵满足某些性质时施加了约束．本文的结论扩展了文献［３］的结果．     

在CASE工具中引入XML视图

从数据库设计的角度出发，在CASE(计算机辅助系统工程)工具中添加了创建XML视图的功能，也就是说在使用CASE对实体及其相互联系建模之后，在创建数据库对象的DDL语句的同时自动的创建此数据库的XML视图．具体的方法是将E-R模型转换为DTD来完成了这个数据库的XML视图的创建，一次性的完成了数据库的设计和此数据库的XML视图的创建，从而避免了程序员为了生成视图而对此数据库进行的二次开发，因此提高了工作效率．     

基于Java技术的WebGIS框架研究

本文力图把当前软件开发技术和Java技术领域中逐渐成熟的设计模式和方法,引入到WebGIS基础开发框架的设计中,以提高框架的可设计性和简化应用开发;表现层中引入MVC模式,数据访问层使用对象一关系映射技术,逻辑层提供有关空间操作的Java APIs(Java Application Program-ming Interface).以此作为框架的基本组成单元.基于Java平台对这个框架的原型进行了实现。以期能为WebGIS框架设计提供一个有意义的参考实现。     

Boiling hysteresis at low temperature on enhanced tubes

The boiling hysteresis phenomenon is studied for a real scale enhanced evaporator tube (2 m long Turbo-B type) with R134a refrigerant used in the flooded evaporator of a centrifugal brine chiller for the ice-making facility. Unlike previous studies of the boiling heat transfer with uniform heat flux and uniform wall temperature, the wall temperature varies along the tube in the present experiment. To see if the similar hysteresis occurs as in the case of uniform wall temperature, a careful control of refrigerant temperature and heat flux is made. We have found hysteresis of the temperature overshoot (TOS) at the onset of nucleate boiling initially at the inlet section of the tube, before it gradually moved downstream section of the tube until the nucleate boiling occupied the whole section of the tube as the inlet temperature increased. The hysteresis became stronger at low refrigerant temperatures. The decreasing trend of heat flux after the contents of the whole tube boiled was different from the increasing trend. This paper provides a guideline how to design the evaporator in order to avoid the abnormal operation of the chillers.     

Reasons for drop in shell-and-tube condenser performance when replacing R22 with zeotropic mixtures. Part 1. Analysis of experimental findings

An experimental and theoretical investigation was made to find out the reasons for the drop in shell-and-tube condenser performance when replacing R22 with a zeotropic mixture R407C. Measurements show that at lower condenser loads the reduction in performance can be as large as 70% compared to the full condenser load. Calculation results are compared with experimental results for two different condensers, one with micro-finned tubes and one with 3-D finned tubes. Calculations show that the degree of mixing of the newly formed condensate on a tube and the drained condensate is a factor influential enough to explain the performance drop. 3-D finned tubes seem to have better mixing in the condensate than integral finned tubes.     

Flash gas bypass for improving the performance of transcritical R744 systems that use microchannel evaporators

The performance of transcritical R744 systems with direct expansion (DX) can be significantly improved by implementing a Flash Gas Bypass (FGB). The idea behind the concept is to bypass refrigerant vapor, created during the isenthalpic expansion process, around the evaporator. By feeding the evaporator with liquid refrigerant, pressure drop is reduced and refrigerant distribution is improved. With R744 as the working fluid, increased refrigerant-side heat transfer coefficients are expected as well. In addition, the FGB concept proves to be beneficial in terms of system design, in particular for combined air-conditioning and heat pumping applications. An experimental comparison to a conventional DX-system reveals that FGB increases the cooling capacity and COP at the same time by up to 9 and 7%, respectively. Even larger improvements are possible in case a variable speed compressor is utilized to match the performance of the conventional DX-system. A simulation model helps to separate the individual improvement mechanisms. It was found that the reduction of refrigerant-side pressure drop is the dominant improvement mechanism of FGB.     

带边框柱剪力墙模型抗震性能试验研究

对于1／15缩尺比例的两个配筋方式不同的带边框柱剪力墙模型在低周反复水平荷载作用下进行了试验研究，分析了墙体边框柱与墙体的共同工作性能．对比研究了带边框柱的中高剪力墙受力特点、破坏和耗能机理．并从承载力、刚度、延性、恢复力特性、耗能能力等方面综合评价了其抗震性能．研究结果表明，带边框柱剪力墙结构具有良好的抗震性能．