基于网络技术的火箭发动机试验台控制测量系统设计与实现

介绍了在WINDOWS2000平台下,基于网络技术的多功能火箭发动机试验台控制测量系统设计与实现。给出了系统的硬、软件结构,完成了系统的研制并通过试验验证了该系统。     

培养创新人才 完善学分制势在必行

随着经济一体化,国家与国家竞争归根到底是人才创新和创造能力的竞争,我国高校如何培养与时代发展趋势相适应的创新人才,完善学分制势在必行。本文从现行学分制存在的问题入手,揭示现行学分制教学管理模式对培养学生创新能力的制约,阐述了为培养创新人才如何进一步完善学分制教学管理模式的措施。     

The (s,Q) inventory model with Erlang lead time and deterministic demand

We develop a simple, approximately optimal solution to a model with Erlang lead time and deterministic demand. The method is robust to misspecification of the lead time and has good accuracy. We compare our approximate solution to the optimal for the case where we have prior information on the lead‐time distribution, and another where we have no information, except for computer‐generated sample data. It turns out that our solution is as easy as the EOQ's, with an accuracy rate of 99.41% when prior information on the lead‐time distribution is available and 97.54–99.09% when only computer‐generated sample information is available. Apart from supplying the inventory practitioner with an easy heuristic, we gain insights into the efficacy of stochastic lead time models and how these could be used to find the cost and a near‐optimal policy for the general model, where both demand rate and lead time are stochastic. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004     

基于灰局势决策理论的维修级别分析方法

简要介绍了某型无人机维修级别分析及灰局势决策理论的一般概念,针对传统维修级别分析中经济性分析的数据来源广、模型可信度较差的情况,研究基于灰局势决策原理建模的一般方法,通过筛选原始数据并修正计算公式,大大减少了冗余计算,最后运用这一模型对某机载无线电设备进行了经济性分析。     

舰载作战训练系统的概念设计

本文介绍了舰载作战训练系统的研究方向、功能、组成及各单元的任务和接口关系,并对关键技术进行了简要说明。     

改进Dijkstra算法在大型城市轨道交通网计价系统中的应用

随着城市地铁建设的迅猛发展,国内众多城市地铁线路均已实现网络化运营。考虑到地铁票价制定的公益性,目前国内大部分城市均以最短路径或最少车站的方式计算线网两车站间的票价。以传统的Dijkstra算法为基准,对传统的Dijkstra算法进行改进,分别采用传统Dijkstra算法和改进Dijkstra算法对长沙地铁1～5号线线网最短距离行走路线进行测算。结果表明,改进后的Dijkstra算法不仅有效地提高了算法的时效性,克服了传统算法时间冗长的缺陷,在一定程度上消除了线路之间累积的误差且提高了线网的可延展性。     

对流层散射无源监视系统最优布局方法

为提高对流层散射无源监视系统对辐射源的定位精度,利用改进粒子群优化算法对分布式监视节点进行最优布局设计。推导了基于电磁波方位到达角定位机制下的几何精度因子。在改进粒子群优化算法中,采用混沌理论初始化所有粒子的初始参数;通过自适应变化的惯性权重和学习因子来提高算法寻优能力;为防止粒子陷入局部最优,利用双子群机制进行寻优,并在两子群之间进行交叉变异操作,以增加粒子的多样性。仿真结果表明:相对于几种常规的布站方式,所提算法能够明显提高监视系统对辐射源的定位精度,运行时间较遍历寻优算法有所减少。     

耐1200℃陶瓷瓦重复使用性能

针对目前比较成熟的耐1 200℃陶瓷瓦开展了1 200℃多次重复热处理,研究了陶瓷瓦的结构和性能演变行为和重复使用性能。结果表明:1 200℃热处理20次后,耐1 200℃陶瓷瓦表现出良好的宏观热稳定性;重复热处理过程中,纤维间烧结,黏接熔融和石英纤维析晶及晶粒长大,使纤维直径发生变化,出现缩颈,进而导致了Z向收缩,收缩率达14%,从而使得压缩强度略有增大,隔热性能降低;经过1 260℃、11次单面辐射加热后,Z向收缩率为5.58%,隔热效果降低了7.59%,但隔热材料能够在6次重复加热后保持材料隔热性能不降低。     

Experimental and numerical investigations of interface properties of Ti6Al4V/CP-Ti/Copper composite plate prepared by explosive welding

Explosive welding technique is widely used in many industries. This technique is useful to weld different kinds of metal alloys that are not easily welded by any other welding methods. Interlayer plays an important role to improve the welding quality and control energy loss during the collision process. In this paper, the Ti6Al4V plate was welded with a copper plate in the presence of a commercially pure titanium interlayer. Microstructure details of welded composite plate were observed through optical and scanning electron microscope. Interlayer-base plate interface morphology showed a wavy structure with solid melted regions inside the vortices. Moreover, the energy dispersive spectroscopy analysis in the interlayer-base interface reveals that there are some identified regions of different kinds of chemical equilibrium phases of Cu–Ti, i.e. CuTi, Cu₂Ti, CuTi₂, Cu₄Ti, etc. To study the mechanical properties of composite plates, mechanical tests were conducted, including the tensile test, bending test, shear test and Vickers hardness test. Numerical simulation of explosive welding process was performed with coupled Smooth Particle Hydrodynamic method, Euler and Arbitrary Lagrangian-Eulerian method. The multi-physics process of explosive welding, including detonation, jetting and interface morphology, was observed with simulation. Moreover, simulated plastic strain, temperature and pressure profiles were analysed to understand the welding conditions. Simulated results show that the interlayer base plate interface was created due to the high plastic deformation and localized melting of the parent plates. At the collision point, both alloys behave like fluids, resulting in the formation of a wavy morphology with vortices, which is in good agreement with the experimental results.     

基于Flexsim的两栖舰船装卸载流程可视化仿真研究

两栖舰船装卸载是登陆作战重要环节,是登陆作战兵力安全、可靠、快速上陆的基本保障.采用Flexsim可视化工具对两栖舰船装卸载两栖车辆作业流程进行可视化建模仿真,通过实时仿真两栖车辆装卸载过程,分析两栖舰船装载方案和装载流程存在的瓶颈问题,从而为优化两栖舰船装载方案和作业流程提供决策依据.