毫米波雷达导引头性能分析与研究

毫米波雷达的频段介于微波频段与红外频段之间,兼有二者固有特性,是武器制导系统较为理想的使用频段。介绍了毫米波雷达制导的技术优点,对复杂气候条件和不同地表环境下35GHz和95 GHz 2种毫米波雷达的性能进行了仿真。仿真结果表明,当目标处在复杂气候环境或较好地表环境(即地表后向散射较弱)时,35 GHz雷达的性能要稍优于95 GHz雷达。     

基于导航定位服务性能的GNSS天线阵 抗干扰统计性能评估方法

基于可用率指标的天线阵统计性能评估方法已成为GNSS天线阵性能评估的共识,但在指标体系及具体细节上,传统的评估方法尚存在不足之处.一是对信号作独立均匀入射的假设,与实际星座特性相差较大,二是单信号可用率指标尚无法满足GNSS接收机对导航定位的需求.针对这两方面的问题,提出了可定位概率、服务可用性等与接收机导航定位服务性能相关联的新指标.结合实际导航卫星星座的分析验证了新指标的有效性.     

基于场的装备物资供应保障适应性配置决策

根据与物理场的相似性,将装备物资供应保障抽象为供应保障场,在定义场强度的基础上,提出基于场强度的反演运算进行供应保障资源配置的方法,给出了通过实时获取战场信息跟踪供应保障场的变化进行保障资源适应性配置决策的流程。     

舰船柴油机冷却系统不解体清洗技术

针对舰船柴油机冷却系统水垢、锈垢严重,维修保养困难的问题,提出舰船柴油机冷却系统不解体清洗技术。通过对舰船柴油机冷却系统材质和垢样的分析,提出由清洗主剂、缓蚀剂和清洗助剂为基础的6种清洗剂配方。对比6种清洗剂配方的缓蚀与清洗效果,确定了最优的清洗剂配方。经柴油机台架试验发现,不解体清洗可有效清除汽缸缸套、缸体等部位的积垢,清除率可达81%,显著改善了热交换效果。     

延迟容忍无线传感器网络动态数据传输

分析现有经典延迟容忍移动无线传感器网络DTMSN(Delay Tolerant Mobile Sensor Networks)数据收集算法.提出了一种基于选择复制的动态数据传输策略ASRAD(Advanced Selective Replication based Adaptive Data Delivery Scheme).其基本思想是把数据消息动态的复制给更有可能与汇聚点通信的传感器节点以达到尽量增大传输成功率和降低传输能耗的目的.ASRAD由数据传输和队列管理两个主要部分组成.     

压力喷嘴常温下雾化特性实验研究

为了满足工程中对喷嘴雾化特性测量的高精度、低成本要求,建立了喷嘴雾化特性实验系统,以自来水为雾化工质,对蒸发冷却压力喷嘴在常温、常压下的雾化特性进行了实验研究。用容积法测量了喷嘴的流量,用最小二乘法对测量数据进行回归分析,得到了喷嘴流量、雾化压力和喷孔直径之间的关联式与流量系数;用机器视觉方法测量了喷嘴的雾化锥角与雾滴尺寸,得到了雾化锥角与雾滴尺寸随雾化压力变化的规律。结果表明:随着雾化压力的增大,喷嘴雾化锥角不断增加,雾滴尺寸不断减小;随轴向距离的增大,D0.632、D0.5、D32有不同幅度的增大,而D0.9则基本不变。     

Investigation on the process parameters of TIG-welded aluminum alloy through mechanical and microstructural characterization

Multi-pass TIG welding was conducted on plates (15×300×180 mm3) of aluminum alloy Al-5083 that usually serves as the component material in structural applications such as cryogenics and chemical processing industries. Porosity formation and solidification cracking are the most common defects when TIG welding Al-5083 alloy, which is sensitive to the welding heat input. In the experiment, the heat input was varied from 0.89 kJ/mm to 5 kJ/mm designed by the combination of welding torch travel speed and welding current. Tensile, micro-Vicker hardness and Charpy impact tests were executed to witness the impetus response of heat input on the mechanical properties of the joints. Radiographic inspection was performed to assess the joint's quality and welding defects. The results show that all the specimens displayed inferior mechanical properties as compared to the base alloy. It was established that porosity was progressively abridged by the increase of heat input. The results also clinched that the use of me-dium heat input (1-2 kJ/mm) offered the best mechanical properties by eradicating welding defects, in which only about 18.26% of strength was lost. The yield strength of all the welded specimens remained unaffected indicated no influence of heat input. Partially melted zone (PMZ) width also affected by heat input, which became widened with the increase of heat input. The grain size of PMZ was found to be coarser than the respective grain size in the fusion zone. Charpy impact testing revealed that the absorbed energy by low heat input specimen (welded at high speed) was greater than that of high heat input (welded at low speed) because of low porosity and the formation of equiaxed grains which induce better impact toughness. Cryogenic (-196 C) impact testing was also performed and the results corroborate that impact properties under the cryogenic environment revealed no appreciable change after welding at designated heat input. Finally, Macro and micro fractured surfaces of tensile and impact specimens were analyzed using Stereo and Scanning Electron Microscopy (SEM), which have supported the experimental findings.     

预制破片侵彻靶板临界跳飞角变化规律

为研究预制破片侵彻靶板的临界跳飞角变化规律,采用数值仿真的方法对预制破片侵彻靶板的临界跳飞角变化规律进行分析.利用LS-DYNA有限元仿真软件,建立了不同形状预制破片侵彻靶板的仿真模型,通过与试验结果相对比的方式验证了模型的可信性.分析了破片形状、破片形状比例系数、破片入射速度和靶板厚度对临界跳飞角的影响规律.分析结果表明:在相同条件下,破片临界跳飞角按照圆柱形、方形和球形预制破片的顺序依次减小,随着破片入射速度和破片形状比例系数的增大而增大,并在一定范围内随着靶板厚度的增加而减小.     

空间兵棋多因素多步骤裁决模型研究

通过对空间兵棋和传统兵棋特点的详细对比和分析,针对空间兵棋在量化裁决中的特点提出了模块化的横向分类型纵向分步骤量化裁决模型.针对空间兵棋在概率裁决中影响因素多种多样的特点,提出了三维概率裁决表概率裁决模型.并通过具体裁决算例,验证了横向分类型纵向分步骤模型的有效性和三维概率裁决表模型的合理性.     

超低频通信抗干扰性能分析

在分析和研究外军超低频通信系统基础上,针对超低频通信系统性能特点,结合现代无线通信干扰基本模式,分析了超低频通信系统优良的抗干扰性能。研究表明,超低频通信系统具有极强的抗干涉能力。