Mitigation effects on the reflected overpressure of blast shock with water surrounding an explosive in a confined space

The mitigation of blast shock with water has broad application prospects. Understanding the mitigation effects on the reflected overpressure of the explosion shock with water surrounding an explosive in a confined space is of great significance for military explosives safety applications. To estimate the effects of the parameters on the reflected overpressure of blasted shock wave, a series of experiments were carried out in confined containers with spherical explosives immersed in a certain thickness of water, and numerical simulations were conducted to explore the corresponding mechanisms. The results reveal that the reflected overpressure is abnormally aggravated at a small scaled distance. This aggravation is due to the high impulse of the bulk accelerated water shell converted from the explosion. With increasing scaled distance, the energy will be gradually dissipated. The mitigation effects will appear with the dispersed water phase front impacting at a larger scaled distance, except in the case of a dense water phase state. A critical scaled distance range of 0.7—0.8 m/kg1/3 for effective mitigation was found. It is suggested that the scaled distance of space walls should be larger than the critical value for a certain water-to-explosive weight ratio range (5—20).     

紫外告警距离测算

紫外告警系统是光电对抗系统的重要组成部分,为军事平台的光电对抗决策提供指引,告警距离是紫外告警系统最重要的技术指标之一,通过对紫外告警系统工作原理分析,基于典型目标(导弹)的紫外辐射特征和紫外辐射的大气传输特性,从工程应用的实际出发,对紫外告警系统告警距离的测算方法进行了研究.研究表明半实物仿真的测算方法在逼真度和操作性上都是令人满意的.     

消防执法引入零容忍政策探析

为了更好地打击消防违法、整治火灾隐患、维护公共安全,探索在消防执法中引入零容忍政策。介绍了零容忍政策的由来及理论依据,分析了消防执法引入零容忍政策的必要性,探讨了实施零容忍打击消防违法、消除火灾隐患的具体意见。     

一种简单的直接数字式空间矢量PWM实现方法

针对常规SVPWM实现困难的缺点,根据零序信号注入方法以及“伏 秒”平衡原理,提出了一种新的SVPWM实现方法,利用这种方法可以直接获得逆变器开关触发时刻,因此可以减小运算器执行周期,提高计算速度.用该方法实现了永磁同步电动机的磁场定向矢量控制,并进行了仿真和实验研究,证明了新方法的正确性和优越性.     

Graph distance‐dependent labeling related to code assignment in computer networks

For nonnegative integers d₁, d₂, and L(d₁, d₂)‐labeling of a graph G, is a function f : V(G) → {0, 1, 2, …} such that |f(u) − f(v)| ≥ d_i whenever the distance between u and v is i in G, for i = 1, 2. The L(d₁, d₂)‐number of G, λ(G) is the smallest k such that there exists an L(d₁, d₂)‐labeling with the largest label k. These labelings have an application to a computer code assignment problem. The task is to assign integer “control codes” to a network of computer stations with distance restrictions, which allow d₁ ≤ d₂. In this article, we will study the labelings with (d₁, d₂) ∈ {(0, 1), (1, 1), (1, 2)}. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2005     

基于相位差变化率方法的单站无源定位技术

无源定位技术有着广阔的应用前景 ,文中在现有单站无源定位方法的基础上 ,介绍了相位差变化率定位法。该方法利用观测平台上两个相互正交的相位干涉仪接收目标辐射电磁波的相位差获取目标的方向信息 ,利用对应的相位差变化率获取目标的径向距离信息 ,从而实现对目标的实时高精度交叉定位。还给出了观测平台水平直线匀速飞行且无飞行姿态变化条件下的定位表达式。仿真结果表明 ,该方法是一种极具发展前途的单站无源定位方法     

基于零动态设计原理的刚体姿态控制

采用四元数,古典的Rodrigues参数和修改的Rodrigues参数来描述刚体旋转运动.基于微分几何中的零动态设计原理,首先构造一个输出映射,使系统具有相对阶{1,…,1}且零动态渐近稳定.然后求出一类反馈控制器,使得系统部分线性化为一指数稳定的线性方程.仿真结果表明,所求控制器能使闭环系统稳定.     

零动态设计方法在鱼雷纵向运动控制中的应用

鱼雷纵向运动方程是非线性微分方程 ,非线性系统近似线性化建模方法有着不可忽视的局限性 .非线性系统的精确线性化设计方法由于其复杂性而限制了它的应用 .将零动态设计方法应用于鱼雷纵向系统 ,为解决鱼雷非线性控制系统稳定设计提供了新的途径 .     

一种采用应力分离法的杂交/混合板壳单元

本文利用一种采用应力分离法的杂交/混合板壳有限元模型分析板壳结构静力学问题。分析表明,该元素在总体水平上没有多余零能模式。而且,该元素通过了薄板的闭锁试验,对薄壳算例也没有观察到闭锁现象。与参考解相比,该元素对各种壳结构均能适用,且收敛性较好,精度也较高。     

毫米波相控阵雷达弹丸脱靶量检测概率分析

定量分析了雷达检测波门及波位的设置、搜索周期、目标及弹丸运动的速度,方向等因素对弹丸检测概率的影响,并针对给定的参数和航路对检测概率进行了计算机仿真。