直升机飞行参数对起降过程中旋翼桨-涡干扰噪声影响的分析

从直升机平衡方程与飞行参数的影响关系出发,推导了一个直升机起降过程中旋翼桨-涡干扰噪声分析的模型,以适用于飞行参数对桨-涡干扰噪声影响的研究。在该模型中,引入了桨涡垂直间距和轨迹马赫数两个关键影响参数的求解。然后,应用该模型分析了飞行参数对直升机起降阶段的旋翼桨-涡干扰噪声的影响,着重计算了不同飞行速度时的桨涡垂直间距和超声速噪声辐射源点随飞行参数的变化。结果表明,桨涡干扰中的超声速噪声辐射源点在一定的飞行状态下会成为主导的噪声源。     

基于有限元的平面变胞机构运动学研究

变胞机构具有在工作阶段切换时,杆件数目或运动数目及连接方式可变的特点,因此现有的基于有限元的机构运动学方法和分析软件无法直接用于变胞机构的分析.基于最小势能原理,推导出了任意曲线的滑动副单元和三节点焊接单元两种有限元模型.根据变胞机构的变胞特征,研究了基于有限元的运动学方法在变胞机构中的应用,给出了其计算步骤和流程.最后利用该方法对3种典型的平面变胞机构进行了分析,其结果表明该方法适合计算机的模块化编程和计算,对变胞机构的运动学研究有重要帮助.     

某型空舰导弹无线电高度表测高故障分析与处理

对某型空舰导弹在飞行试验中出现的无线电高度表测高故障进行了分析和定位,并对该型高度表软件进行了改进,为此类故障提供了一种分析方法和排故模式,对其它型号导弹也有着借鉴作用。     

基于Geomagic Studio技术实现叶轮重构

<正>逆向工程技术已成为现代企业开发新产品的一种重要设计手段。为了满足客户产品逆向设计的要求,对产品设计思路和技术实现途径也有不同的选择。     

SIMOTION在数字化对接系统中的多轴同步控制应用

针对数字化对接系统,基于运动控制系统SIMOTION提出了虚拟轴的方法,实现多轴同步控制,开发了SIMOTION控制接口软件,实现数据和指令的可靠传输。数字化对接系统中的试验结果验证了多轴同步控制方法的有效性。     

航天测控站资源优化配置的元建模与寻优方法

基于不同需求提出了一种比较通用的指标评价函数,构建了地面站资源配置的统计模型和基于神经网络方法的仿真元模型。在元模型求解过程中,提出了回代法寻找最优配置的思想,即将每次迭代求解得到的优化配置点代入下次迭代训练中,以提高网络的逼近性能和泛化能力。算例表明,该方法能够求得地面资源的较优配置,求解效率高。     

Stability and shape analysis of relative equilibrium for three-spacecraft electromagnetic formation

The invariant shapes for close formation flying with inter-craft electromagnetic force ensure several potential space applications. However, the 6-DOF relative equilibrium problem has not been systematically investigated. This paper mainly analyzes the invariant shapes of relative equilibrium for the three-spacecraft electromagnetic formation, and studies the families of invariant shape solutions with real and constant magnetic moments as well as their linear stability. The problem is examined based on the full nonlinear coupled dynamic models for collinear and general triangular configurations. The relative equilibrium conditions are analyzed to determine whether an invariant shape do exist, and the corresponding families of invariant shape solutions are identified for static and spinning configurations respectively. Finally, the linear stability of such invariant shapes is numerically discussed, which have shown that most invariant shapes are unstable and controllable.     

Silkworms culture as a source of protein for humans in space

This paper focuses on the problem about a configuration with complete nutrition for humans in a Controlled Ecological Life Support System (CELSS) applied in the spacebases. The possibility of feeding silkworms to provide edible animal protein with high quality for taikonauts during long-term spaceflights and lunar-based missions was investigated from several aspects, including the nutrition structure of silkworms, feeding method, processing methods, feeding equipment, growing conditions and the influences on the space environmental condition changes caused by the silkworms. The originally inedible silk is also regarded as a protein source. A possible process of edible silk protein was brought forward in this paper. After being processed, the silk can be converted to edible protein for humans. The conclusion provides a promising approach to solving the protein supply problem for the taikonauts living in space during an extended exploration period.     

河北省农村居民体育生活方式调研

本文采用文献资料法、问卷调查法,针对河北省约5万个行政村中的3000位农村居民,按照行政区域、经济发展、性别、年龄原则进行筛选。就河北省新农村建设过程中农村居民的体育生活方式的现状及影响因素等问题进行调查。目的是对河北全省农村居民进行体育生活方式的调查,明确在河北省进行新农村建设的过程中农村居民的体育生活方式的现状及其...