旋转受照状态下天线温度场仿真分析

在进行星表天线地面真空热环境试验过程中,传统的红外加热设备会造成测量光路遮挡、降温速率减慢等影响。为提高试验准确性,提出了基于天线旋转受照的真空热试验方法。利用虚拟热试验平台对旋转受照状态下天线温度场进行仿真分析,得到天线温度场的分布与变化,并与试验数据对比,验证了仿真建模的准确性和试验方法的可行性。     

小型试验固体火箭发动机研究

从理论上分析了影响固体火箭发动机性能散布的主要因素,设计了相应配套的小型试验固体火箭发动机,用于提高燃速测试精度,并应用于大型发动机的研制和批产。理论分析和测试结果表明,燃速的测试精度以及复合固体推进剂自身的燃速散布是影响固体火箭发动机性能的最主要因素,把握了复合固体推进剂燃速,可减小性能散布,确保大型固体火箭发动机批次研制和生产性能的稳定性和准确性。     

小波去除噪音算法研究

介绍了小波变换滤除噪音的机理和与傅立叶变换相比的优越性,其中包括确定性噪音和随机噪音。讨论了增强去噪效果的几种改进方案并提出一种试验估计去噪方法,对工程应用有一定的实用价值。     

Decision-making of Aircraft Optimum Configuration Utilizing Multidimensional Game Theory

As multi-discipline coupling and components interference often affect the aircraft configuration decision-making and analysis during conceptual design process, this article presents an approach of multidimensional game theory based on aircraft components to deal with this problem. The idea is that the configuration decision-making process is regarded as the game for different disciplines and technologies, and the aircraft components are players. The payoff function with highest total gain means that according to the game protocols and multidimensional theory, the optimal aircraft configuration within the strategy set will be chosen. The decision-making model is applied to conceptual design process of the high altitude long endurance (HALE) unmanned aerial vehicle (UAV) based on the assessment of technological risk. The obtained optimum configuration is quite consistent with the current HALE UAV development trends. Thus, taking into account the coupling and interference factors, the multidimensional gaming model based on aircraft components will be an effective analysis method in the decision-making process of aircraft optimum configuration.     

Analysis for Strength Test of Butt-jointed Thin-wall Steel Pipe

目前薄壁钢管对接焊缝强度的计算常采用参考文献[1]中公式,此公式为国外早期的经验计算公式,但仅适用于气焊钢管,而薄壁钢管常采用C02保护焊.本文通过焊接钢管拉伸试验分析,推导出了适用于计算薄壁焊接钢管对接焊缝强度的公式以及CO2保护焊参数取值.     

PLC实现机床主轴自动换挡

以一台数控五坐标机床技术改造为实例，采用 Ｐ Ｌ Ｃ 实现主轴的自动换挡。通过状态及数据接口分析，提出主轴换挡的控制流程，总结出在机床控制中主轴换挡控制的一般原理与方法。     

Passive target tracking using maximum likelihood estimation

Estimation of target trajectory from passive sonar bearings and frequency measurements in the presence of multivariate normally distributed noise, with unknown inhomogeneous general covariance, is modeled as a nonlinear multiresponse parameter estimation problem. It is shown that maximum likelihood estimation in this case is identical to optimizing a determinant criterion which has a concise form and contains no elements of unknown covariance matrix. A Gauss-Newton type algorithm using only the first-order derivatives of the model function and a new convergence criterion, is presented to implement such estimation. The simulation results demonstrate that performance of the maximum likelihood estimation method with the above noise model is superior to that with the traditional noise assumption     

高教机天线布局影响通讯距离研究与改进

某型高级教练机在试飞中,出现空地通讯距离不满足战技指标要求的问题。经过分析发现,由于超短波电台天线作为单极天线,其安装布局未满足天线本身要求,即接地面尺寸过小、近场区环境复杂等,导致天线辐射性能受到影响。本文对天线阻抗和方向性系数进行了研究分析,并根据飞机情况制定相应的改进方案。     

如何开展院校任期经济责任审计

当前任期经济责任审计已成为审计部门的一项重要职责，如何开展院校任期经济责任审计，是摆在我们内审工作面前的重大课题。本从经济责任审计的重要性入手，对搞好经济责任审计的途径与方法作了探讨。     

Java赋值的特色

Java是一种与平台无关、可靠性强、小而灵活的编程语言。其赋值颇具特色。普通的赋值是用赋值运算符(=)进行的。它的意思是“取得右边的值,把它复制到左边”。右边的值可以是任何常数、变量或者表达式,只要能产生一个值就行。但左边的值必须是一个明确的、已定义的变量。也就是说,它必须有一个物理性的空间来保存右边的值。举个例子来说,可将一个常数赋给一个变量(A=4;)但不可将任何东西赋给一个常数(比如不能4=A)。对主数据类型的赋值是非常直接的。由于主类型容纳了实际的值,而且并非指向一个对象的指针,所以在为其赋值的时候,可将来自…