Experimental Investigation on Performance of Pulse Detonation Rocket Engine Model

The PDRE test model used in these experiments utilized kerosene as the fuel, oxygen as oxidizer, and nitrogen as purge gas. The solenoid valves were employed to control intermittent supplies of kerosene, oxygen and purge gas. PDRE test model was 50 mm in inner diameter by 1.2 m long. The DDT （deflagration to detonation transition） enhancement device Shchelkin spiral was used in the test model. The effects of detonation frequency on its time-averaged thrust and specific impulse were experimentally investigated. The obtained results showes that the time-averaged thrust of PDRE test model was approximately proportional to the detonation frequency. For the detonation frequency 20 Hz, the time-averaged thrust was around 107 N, and the specific impulse was around 125 s. The nozzle experiments were conducted using PDRE test model with three traditional nozzles. The experimental results obtained demonstrated that all of those nozzles could augment the thrust and specific impulse. Among those three nozzles, the convergent nozzle had the largest increased augmentation, which was approximately 18%, under the specific condition of the experiment.     

锥体目标进动的宽带雷达特征分析

进动是锥体目标空间自旋飞行时特有的运动特性,通过刚体姿态动力学原理,采用微动分析方法分析了光滑表面锥体弹头目标的空间进动模型,并由雷达电磁散射原理建立了目标宽带回波模型.通过散射点仿真模型和电磁仿真数据,采用周期检验的方法分别对锥顶和锥尾散射点的进动参数进行提取,验证了分析和模型的正确性.     

Practical approaches to handle the singularities of a wrist-partitioned space manipulator

Space robotic systems are expected to play an increasingly important role in the future. However, the control methods based on the inverse kinematics are affected by singularities. In this paper, practical approaches are proposed to solve the problems of a wrist-partitioned space manipulator. For spacecraft-referenced end-point motion control, we presented the singularity separation plus damped reciprocal (SSPDR) method, which separates the singularity parameters from the inverse of the Jacobian, and replaces their reciprocals using the damped reciprocals. For another control strategy, i.e. inertially referenced end-point motion control, including spacecraft attitude-controlled mode and free-floating mode, the linear momentum equation is used to eliminate three independent variables. With modifying some expressions, the SSPDR method is utilized to solve the singularities of spacecraft attitude-controlled space robot. When the space robot is free-floating, the singularities, i.e. the so-called dynamic singularities, cannot be predicted according to its kinematic structure. Combining with the measured angular velocity of the base, the dynamic singularity handling problem is transformed into real-time kinematic singularity avoiding problem, which can be solved by the SSPDR method. Since the SVD decomposition, the estimation of the minimum singularity value, and the calculation of the generalized Jacobian matrix are not required, the algorithm has lower computation load. Another advantage is that, only the accuracy of part velocity components is reduced by adding the damped coefficients. Simulation results verify the proposed approaches.     

基于改进的蚁群算法的亚轨道再入飞行器弹道优化

基于阻力与能量再入导引律,用改进的蚁群算法优化SLV再入阻力-能量关系剖面,其优化的性能指标为总吸热量最小,并采用LQR法跟踪参考弹道.仿真结果表明,优化方法简便易行,跟踪器性能良好.     

卫星编队飞行相对位置保持的脉冲控制

研究了卫星编队飞行相对位置保持的脉冲控制方法。分析基于动力学模型的周期脉冲控制策略,讨论其工程可实现性,并在考虑存在较大测量噪声情况下提出了周期多步脉冲控制的方法。数字仿真的结果比较显示了这种多步脉冲控制方法的有效性。     

灵巧噪声干扰与雷达SLB和SLC的对抗分析

灵巧噪声干扰技术是雷达电子对抗领域一项关键的基础性技术.在简要介绍旁瓣消隐(SLB)和旁瓣对消(SLC)抗干扰技术原理的基础上,分析灵巧噪声对SLB、SLC的干扰能力及干扰效果.分析结果表明灵巧噪声干扰不但具有更优越的欺骗干扰-噪声干扰功效,还具有特殊干扰功能.     

碳纤维复合材料卫星天线反射面型面精度稳定性分析

文章简述了卫星天线的组成、制造工艺过程,着重对影响天线反射面型面精度和尺寸稳定性有关内容,从材料特性、铺层分析、成型模具材料和产品质量控制等内容进行了分析。     

基于稀疏网格配置方法的超燃冲压发动机高维不确定性量化

为了定量地研究随机不确定性对超燃冲压发动机性能评估及优化设计可能带来的影响及其规律特征,基于高斯过程描述发动机工作状态及来流环境等控制参数随机误差,建立由自由来流条件、进气道压缩系统以及燃烧加热等构成的发动机输入边界不确定性表征.耦合全局敏感度分析、稀疏网格技术、概率配置方法及等压燃烧热力学分析模型,提出了面向超燃冲压...     

一种典型工程结构风致振动现场测量

对一个建筑结构风致振动进行了现场测量研究.结构风振位移采用摄影法测量,由于观测目标不可触及,测量中采用了一种新的摄影定标方法,即利用正多边形物体来标定摄影比例尺,解决了难以接近的观测目标的动态位移测量问题.现场测量得到了某特定气象条件下当地大气湍流的平均风速、湍流度、风谱、积分尺度等统计量和结构风振最大位移,固有频率,阻尼比等振动参数.     

面向软件源程序的模型检验技术

模型检验技术作为一种有效的形式化方法,能够提供严格的软件质量保证.介绍了面向软件源程序的模型检验技术的工作流程,并在此基础上针对规约性质描述问题,提出一种与源代码独立的、语法简单易用的、符合程序员开发习惯的规约描述语言,并给出一种轻量级的程序模型检验方法,它基于程序控制流图的路径遍历,支持函数过程内验证、函数过程间验证、规约检查.