3种不同形状电枢对线圈炮发射性能影响的仿真分析

分析电磁线圈炮基本原理，建立单级感应线圈炮数学模型，并借助Matlab仿真软件，对3种不同形状（锥体、半球体和圆柱体）电枢的线圈炮进行仿真。分别得到电枢与驱动线圈之间互感与互感梯度的相对位置变化曲线、电枢内涡流分布及随时间变化曲线，3种发射器在同一坐标下的射弹电磁力-时间和速度-时间变化曲线。通过对比分析，确定了线圈炮合理的电枢形状，为线圈炮的系统结构设计奠定了基础。     

几何光学法用于飞机进气道 RCS 的计算

运用电磁场理论的几何光学法解决飞机进气道雷达截面(RCS)的计算。计算结果与实测值基本相符,使得复杂的飞机进气道雷达特性可以简化处理。此法既简单又严密。     

涵道风扇外形参数对气动特性的影响

以某涵道风扇为原型,从理论上分析涵道扩张角对涵道风扇气动特性的影响。运用滑移网格模型,采用三维不可压黏性Navier-Stokes控制方程,利用SST k-ω湍流模型,计算两叶桨气动特性,并与试验结果对比,验证该方法的可行性。分别计算涵道风扇在悬停状态下,3000~8500 r/min转速范围内,涵道唇口外形、扩张角和涵道高度对气动特性的影响,并对流场进行分析。椭圆形唇口的涵道风扇总拉力系数小,气动效率低;当涵道扩张角在8.2°附近时,功率系数相对最小,随着扩张角增大,在桨盘下方靠近涵道壁面附近出现气流分离;涵道拉力系数对涵道风扇高度的变化敏感度低,随着高度增加功率系数略有下降。     

Analysis of the mass of behind-armor debris generated by RHA subjected to normal penetration of variable cross-section EFP

Analyzing the mass of behind-armor debris (BAD) generated by Rolled Homogeneous Armor (RHA) subjected to normal penetration of variable cross-section Explosively Formed Projectile (EFP) is the purpose of this paper. So theoretical analysis, numerical simulation and experimental data are combined to analyze the influence of variable cross-section characteristic on the time history of crater radius. Moreover the relationships between time history of crater radius (as well as mass of BAD) and the thickness of RHA (from 30 mm to 70 mm) and the impact velocity of EFP (1650 m/s to 1860 m/s) are also investigated. The results indicate that: 1) being compared to the variable cross-section characteristic is ignored, the theoretical time history of crater radius is in better agreement with the simulation results when the variable cross-section characteristic is considered; 2) being compared to the other three conditions of plug, the theoretical mass of BAD is in the best agreement with the simulation results when the shape of plug is frustum of a cone and the angle between generatrix and bottom is 45° and the axial length of mushroom is considered.     

Zernike矩的不变性分析及其改进

Zernike矩作为一种基于区域的形状描述子,具有良好的旋转不变性,能够很好地提取图像内部的形状信息。介绍了Zernike矩的定义,对其不变性进行了深入分析,并对Zernike矩算法进行了改进,使其在具有良好的旋转不变性的基础上,也具有较好的平移不变性和比例不变性。结果表明,改进后的Zernike矩具有更好的不变性,可更好地应用于图像识别中。     

目标起伏特性对雷达威力性能的影响分析

介绍了典型雷达目标RCS起伏模型,阐述了起伏目标在实际中的应用,建立了目标损耗和雷达作用距离之间的关系,为不同目标的等效替代推算提供了理论依据.验证了雷达目标满足卡平方分布时发现概率和起伏因子之间的关系.并针对不同类型的起伏目标,建立了雷达探测距离和发现概率之间的关系,为雷达的威力检测和飞行目标的航线设计提供依据.     

Some probability functions in reliability and their applications

There has been much research on the general failure model recently. In the general failure model, when the unit fails at its age t, Type I failure (minor failure) occurs with probability 1 ? p(t) and Type II failure (catastrophic failure) occurs with probability p(t). In the previous research, some specific shapes (constant, non‐decreasing, or bathtub‐shape) on the probability function p(t) are assumed. In this article, general results on some probability functions are obtained and applied to study the shapes of p(t). The results are also applied to determining the optimal inspection and allocation policies in maintenance problems. © 2006 Wiley Periodicals, Inc. Naval Research Logistics, 2007     

基于颜色及梯度统计特征的结核杆菌目标识别

提出一种基于颜色及梯度统计特征的结核杆菌目标识别算法。首先基于HSV颜色空间进行图像预分割,然后在CIE L*a*b*颜色空间进行自适应分割以提取目标精细几何形状。为了适应背景的复杂变化,基于色调一致性假设对疑似目标进行色调一致性检验并剔除大部分伪目标。为了将重叠粘连目标从伪目标中分离出来,提出两个梯度统计特征,然后结合目标的面积、周长、长宽比、圆形度、粗糙度等形态特征,组成7维特征向量送入贝叶斯分类器进行分类。实验结果表明,本文算法能适应标本、染色及图像背景等复杂变化,目标识别率可达91%。     

基于分离逻辑的程序分析技术

分离逻辑是John C Reynolds和Peter O’Hearn于2000年提出的基于Hoare逻辑分析程序中动态分配内存和指针别名的逻辑理论。首先回顾了分离逻辑系统的理论框架,然后讨论了分离逻辑在程序分析领域中符号执行、形态分析和并发程序分析验证这些领域中的应用成果,最后介绍了分离逻辑在程序分析技术中当前主要的研究方向。     

新型钢-混凝土组合板的力学性能研究

以加劲肋形式、组合板厚度和栓钉布置为参数,进行了9块新型组合板的力学性能试验.试验结果表明,组合板的正截面承载力可按基于修正平截面假定的极限状态计算;组合板的跨中挠度,可在按现行规范计算的基础上,加上考虑界面滑移影响的附加变形值予以修正.