某型船机舱通风系统设计

根据某型船机舱设备及其布置特点,按照机舱通风系统设计要求,计算确定了前、后机舱通风量．根据机舱通风量和抽风式通风组织方案,选择了合适的通风设备．在设计中分析比较了若干通风系统设计方案,最后确定采用抽风式机舱通风系统．该船航行试验证明,机舱通风系统设计十分成功．     

ER2MD：一种ER模型到多维模型的转换算法

多维模型是数据仓库概念设计不可缺少的工具,将传统数据库实体关系模型直接转换到多维模型,势必在很大程度上缩短数据仓库系统的开发周期.针对数据仓库概念设计需求,在传统数据库基础上,提出一种面向多维模型的转换算法ER2MD.该算法可将满足一定条件的实体关系模型转换到多维模型,产生的多维模型符合广义多维范式,能够确保多维数据库分析计算的有效性,进而有利于物理数据库的设计.     

An algorithm for maximizing target achievement in the stochastic knapsack problem with normal returns

We consider the stochastic linear knapsack problem in which costs are known with certainty but returns are independent, normally distributed random variables. The objective is to maximize the probability that the overall return equals or exceeds a specified target value. A previously proposed preference order dynamic programming-based algorithm has been shown to be potentially suboptimal. We offer an alternative hybrid DP/branch-and-bound algorithm that both guarantees optimality and significantly outperforms generating the set of Pareto optimal returns.© 1993 John Wiley & Sons, Inc.     

弹体旋转角速度的测量

本文研究了弹体旋转角速度测量的机理,采用极化栅网,使弹体的反射信号包含有弹体的旋转角速度信息,并且通过实验予以证明。文中提出了一种旋转角速度测量系统。本文对测量弹体旋转角速度是有一定帮助的。     

基于DCPM-FGA的隐马氏模型的参数训练

建立了一种将直接比较比例方法与模糊遗传算法结合在一起用于隐马氏模型参数训练的方法。针对不同的码本大小进行了仿真试验。结果表明,在码本较大时该方法效果要好于B W算法和Viterbi算法,码本较小时两种方法性能相近。     

基于对象petri网的雷达组网系统应用效能研究

建立了复杂环境下雷达网防空作战系统OPDL模型,并嵌入相关的数学模型,对雷达网在防空作战中的应用效能进行了仿真分析,给出了定量的分析结论。研究表明,雷达组网技术的运用有效提高了防空武器系统的作战能力,为深入分析研究雷达网的作战效能奠定了基础。     

电子对抗装备软件的测试策略与方法

在阐述了电子对抗装备软件特点的基础上,对研制电子对抗装备软件过程中的测试策略与方法进行了初步的研究,并对在实施测试过程中的几个问题进行了探讨.     

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。     

Evaluation of effectiveness of polymer coatings in reducing blast-induced deformation of steel plates

Incorporating elastomers such as polymers in protective structures to withstand high energetic dynamic loads, has gained significant interest. The main objective of this study is to investigate the influence of a Polyurea coating towards the blast-induced response in steel plates. As such, Polyurea coated steel plates were tested under near-field blast loads, produced by the detonation of 1 kg of spherical nitromethane charges, at a standoff distance of 150 mm. Mild steel (XLERPLATE 350) and high-strength steel (BIS80) plates with thicknesses of 10 mm were Polyurea coated with thicknesses of 6 mm and 12 mm on either the front (facing the charge) or the back face. The deformation profiles were measured using 3D scanning. Numerical simulations were performed using the non-linear finite element code LS-DYNA. The strain-dependent behaviour of the steel and Polyurea were represented by Johnson-cook and Money-Rivlin constitutive models, respectively. The numerical models were validated by comparing the plate deflection results obtained from the experiments and were then used in the subsequent parametric study to investigate the optimum thickness of the Polyurea coating. The results indicate that back face coating contributes towards an approximately 20% reduction in the residual deformation as well as the absence of melting of the Polyurea layer, while the front-face coating can be used a means of providing additional standoff distance to the steel plates.