液体火箭发动机热力组件动力学模型

 为了评判不同假设条件下得出的几种热力组件动力学模型的特点和适用范围,对其频率特性进行分析,并探讨了主要参数的影响规律。对于双组元非等温燃气流,在低频范围内采用考虑熵波效应的绝热流动模型更加精确。燃烧温度与混合比关系的无量纲斜率值越大,推进剂流量波动产生的熵波影响越明显。通过在分布参数流动模型中添加指数衰减率来表示熵波随频率的增大而耗散。改进的声学模型形式简单,既能在低频范围内描述熵波,又能在高频范围表征熵波的耗散,可以在很宽的频率范围内合理地描述燃气流动的动态特性。     

空间相机电子设备热设计

电子设备是空间相机重要发热源,需要通过合理的热设计将热量及时导走,维持电子元器件温度不致过高。根据空间相机各电子设备所处空间环境、结构特点及内部电子元器件热特性,提出了相应的多种不同的热设计方法,采用热仿真分析、热平衡试验两种方法对设计进行了验证,对比了两种方法所获取的温度数据。结果表明两种方法所获取元器件结温均满足温度降额指标要求,且相差不大,充分验证了热设计方案的有效性和仿真分析的准确性。     

An error analysis and optimization method for combined measurement with binocular vision

The accurate measurement of surfaces of large aviation components is vital for the assessment of manufacturing and assembly quality of such components. To satisfy the measurement requirement of large-size components, most current researches pay more attention to combined measurement methods utilizing different measuring instruments, but the related researches on error analysis and optimization methods are not taken enough attention. This paper proposes a combined laser-assisted measurement method with feature enhancement techniques, and it also develops an error propagation model of the main factors affecting the overall measurement error in detail. Firstly, the surface of a large-size component is measured by the measurement system at multiple stations. Secondly, a control point coordinate system is established as a bridge to unify all local measurement data into the global coordinate system. To improve the overall measurement accuracy, the pixel extraction error as a key factor causing the overall measurement error is analyzed in detail. Next, the error propagation model is established, and some optimization strategies of layout for minimizing measurement error and transformation error are researched. Finally, experiments are carried out to verify the effectiveness of the proposed method. The results show that the measurement error of the proposed method reaches 0.073% and 0.14% with a 1D standard ruler and a flat plate, respectively.     

振动监测与故障诊断技术在“风云二号” 扫描辐射计中的应用

转动部件的状态监测和故障诊断有多种方法,其中振动诊断技术在被诊断系统的信号采集、数据处理、故障识别和诊断中显示出简便可靠的优越性,尤其适用于不停机在线监测和诊断报警。“风云二号”扫描辐射计由于其特征频率为较高的67 Hz与200 Hz,尤其适用于通过测量加速度来监测状态和诊断故障。振动诊断技术将为确保卫星的长寿命和高可靠提供有力保障。     

基于函数型数据的广义线性回归模型

函数型数据的回归分析研究主要集中在函数型线性模型。不要求因变量为连续型随机变量,可以为离散型或属性数据(对应于泊松或Logistic回归),对同时含有数值型多元变量和函数型变量的广义线性模型的估计问题进行分析,采用非参数方法得到了参数部分和非参数部分的估计量,并给出了一种重加权算法进行参数求解,解决了含数值型和函数型混合数据类型自变量的回归问题,同时扩展了函数型线性模型的应用范围。估计过程中,分别采用了函数型主成分和B样条基函数,并给出了基函数个数选择的准则。数值模拟结果表明,所提出方法具有良好的可行性与正确性。      

Structural Nonlinear Flutter Characteristics Analysis for an Actuator-fin System with Dynamic Stiffness

The flutter characteristics of an actuator-fin system are investigated with structural nonlinearity and dynamic stiffness of the electric motor. The component mode substitution method is used to establish the nonlinear governing equations in time domain and frequency domain based on the fundamental dynamic equations of the electric motor and decelerator. The existing describing function method and a proposed iterative method are used to obtain the flutter characteristics containing preload freeplay nonlinea...     

气相色谱法检测无水肼中水含量的不确定度评定

对气相色谱法检测无水肼中水含量过程的不确定度进行评定,系统分析检测过程中不确定度来源和各不确定度分量对分析结果的影响,通过对不确定度的分量进行分析和合成,可知标准溶液配制的过程、标准曲线的拟合和测量样品时的重复操作带来的不确定度分量是影响无水肼中水含量测定不确定度的主要来源.     

Recent Developments on Damage and Fracture of Thin-Walled Complex Components Produced by Spinning

The spinning technique has been widely used in the manufacture of aerospace thin-walled axisymmetric components because of its excellent formability. Damage and fracture, as the important defects that often occur and must be avoided in the forming and service stages of components, have attracted much attention of researchers. In this paper, the fracture behavior and laws of spinning components such as conical parts, tubular parts, and components with inner ribs are summarized, the typical coupled and uncoupled ductile fracture models are introduced, and their applications in spinning are analyzed. Meanwhile, the recent developments on the modified ductile fracture model in analyzing damage and fracture mechanisms of spinning are emphatically introduced. The results could provide guidance for the selection and establishment of appropriate ductile fracture models in the finite element simulation for the accurate prediction and analysis of fracture moment, location, form, damage mechanism, and evolution law, and help the development of precision spinning techniques for high-performance thin-walled complex components.     

飞机电源系统参数测试软件的通用性设计

从自动测试系统通用性的角度出发,阐述了ATS软件通用性的实现及关键技术.利用MFC在组件技术的基础上完成了飞机电源系统通用参数测试软件功能组件开发,同时结合GL Studio完成了图形控件的设计和开发.借助于LabWindows/CVI,给出了通用测试软件集成的详细说明和方法步骤.     

小尺寸封装(SOP)器件焊点可靠性研究

从器件引脚镀层种类、厚度、焊接参数和焊盘设计等几个方面对小尺寸封装(small outline package,简称SOP)器件焊点可靠性的影响作了分析,给出了提高焊点可靠性的方法,并通过UG软件建立了电路板和SOP焊点的三维有限元模型,进行了SOP器件焊点在近似试验载荷条件下的应力应变三维有限元数值模拟,得出了焊点内部精确的应力应变分布。