中间件技术的研究及应用

本文在分析了分布式应用系统体系结构发展变化的基础上．阐述了中间件的概念、功能和在可重用、多异构数据源应用系统的作用，对ODBC、BDE／IDAPIT、0LEDB／ADO和JDBC等分布式数据库中间件；CGI、lSAPI／NSAPI、ASP、JSP等中间件进行了分析比较，并给出了中间件技术在教务管理信息系统的应用实例。     

构架式可展天线机构自由度分析——拆杆等效法

针对四面体构架式可展天线机构的多环耦合特性,提出了一种空间多环耦合机构的自由度分析方法——拆杆等效法。首先拆除四面体基本可展单元机构的耦合约束链,将剩余部分视为一个并联机构,然后应用螺旋理论分析各输出节点的自由度数目及性质,进而构造各输出节点与定节点之间的等效串联运动链,最后复原拆除的耦合约束链得到四面体基本可展单元的等效机构,应用修正的G-K公式计算等效机构的自由度数目,并基于反螺旋理论分析等效机构的自由度性质,从而获得四面体基本可展单元的运动特性。根据四面体基本可展单元的等效机构及其组合方式对最小组合单元及大尺寸构架式可展天线机构的结构进行了化简,并根据其几何特征约束方程推导了最小组合单元及大尺寸构架式可展天线机构的自由度。建立了由27个四面体基本可展单元组成的构架式可展天线机构的仿真模型,对该机构的自由度进行了验证,结果表明提出的拆杆等效法求得的自由度正确,为进一步分析此类天线机构的运动学和动力学奠定了基础,同时为其他类型的空间多环耦合机构的自由度分析提供了一种新的思路。     

Improved NSGA-II Multi-objective Genetic Algorithm Based on Hybridization-encouraged Mechanism

To improve performances of multi-objective optimization algorithms, such as convergence and diversity, a hybridization- encouraged mechanism is proposed and realized in elitist nondominated sorting genetic algorithm （NSGA-Ⅱ）. This mechanism uses the normalized distance to evaluate the difference among genes in a population. Three possible modes of crossover operators--＂Max Distance＂, ＂Min-Max Distance＂, and ＂Neighboring-Max＂--are suggested and analyzed. The mode of ＂Neighboring-Max＂, which not only takes advantage of hybridization but also improves the distribution of the population near Pareto optimal front, is chosen and used in NSGA-Ⅱ on the basis of hybridization-encouraged mechanism （short for HEM-based NSGA-Ⅱ）. To prove the HEM-based algorithm, several problems are studied by using standard NSGA-Ⅱ and the presented method. Different evaluation criteria are also used to judge these algorithms in terms of distribution of solutions, convergence, diversity, and quality of solutions. The numerical results indicate that the application of hybridization-encouraged mechanism could effectively improve the performances of genetic algorithm. Finally, as an example in engineering practices, the presented method is used to design a longitudinal flight control system, which demonstrates the obtainability of a reasonable and correct Pareto front.     

Friction moment analysis of space gyroscope bearing with ribbon cage under ultra-low oscillatory motion

This paper presents the model of calculating the total friction moment of space gyroscope ball bearings which usually work under ultra-low oscillatory motion and are very sensitive to the friction moment. The aim is to know the proportion of the friction moment caused by each frictional source in the bearing＇s total friction moment, which is helpful to optimize the bearing design to deduce the friction moment. In the model, the cage dynamic equations considering six degree-of-freedom and the balls dynamic equations considering two degree-of-freedom were solved.The good trends with different loads between the measured friction moments and computational results prove that the model under constant rate was validated. The computational results show that when the speed was set at 5 r/min, the bearing＇s maximum total friction moment when oscillation occurred was obviously larger than that occurred at a constant rate. At the onset of each oscillatory motion, the proportion of the friction moment caused by cage in the bearing＇s total friction moment was very high, and it increased with the increasing speed. The analyses of different cage thicknesses and different clearances between cage pocket and ball show that smaller thickness and clearance were preferred.     

飞行器雷达罩设计方法的研究

详细分析了飞行器雷达罩设计过程中的基本问题。基于多目标优化设计方法建立了雷达罩结构参数求解的数学模型，给出了求解方法。考虑到雷达罩的安全使用要求，分析了雷达罩防雷击部件的基本要求，提出了设计方法，给出了防雷击部件布置的经验公式。同时还研究了用于飞行器雷达罩金属部件的吸波材料电磁波吸收机理，以及吸波材料电性能设计原理和基本布置准则     

亚热带气象条件下直升机雷达罩常见损伤及设计对策

本文通过对亚热带气象条件下使用的部分直升机雷达罩故障统计及分析,给出了雷达罩系统在亚热带高盐雾地区使用时外观及性能的变化规律以及常见的结构损伤形式,为直升机雷达罩在该类地区更合理地使用及维修提供了较为准确的依据。同时,通过分析对比,本文还给出了亚热带气象条件下使用的直升机雷达罩在设计及制造时可以借鉴的基本原则。     

IMP S-网络接口通信可靠性的改进

由于在Ｓ－网络上的ＩＭＰ Ｓ－网络接口在线路上存在自身的缺陷，往往使其与主控计算机之间的通信受阻。本文从线路上改进了ＩＭＰ Ｓ－网络接口，从而使通信更加稳定、可靠。     

高速加工HSK工具系统的力学模型

根据HSK工具系统的结构和工作机理建立了HSK工具系统的力学模型,分析了影响工具系统刚度的主要因素和载荷与加工质量之间的关系,揭示出HSK工具系统刚度变化的基本规律,理论分析结果与实验结果吻合.在此基础上,提出评估工具系统的性能不仅要考虑工具系统的静刚度,而且要进一步考虑工具系统的动刚度.最后,给出了HSK工具系统型号的选择原则,并建立了相应的优化操作条件.     

无人机飞行控制系统先进设计技术评述

首先简要回顾了无人机飞行控制系统经典设计方法,然后着重论述了目前国外在无人机飞行控制系统设计领域的最新研究成果,包括动态逆技术、BACKSTEPPING自适应技术及综合制导与控制技术。     

密集有源多假目标的压制干扰效果分析与仿真

多假目标干扰在现代电子战中应用日益广泛。随着工作状态参数的不同,多假目标干扰呈现出不同的干扰效果。在讨论密集多假目标产生方法的基础上,针对两种不同的恒虚警处理,详细分析了密集多假目标的干扰效果,得到一些有价值的结论:当密集程度较高时,多假目标干扰可以起到类似噪声的压制作用,最后进行了仿真验证。