人员流动风险分析与控制

本文从风险管理的角度研究人员流动问题,给出了人员流动风险的定义和分类,并分别对人员流入风险和人员流出风险的成因进行了分析,最后提出了风险控制策略。     

飞机纵向高阶等效系统品质参数辨识研究

对飞机纵向高阶等效系统模型的可辨识性进行了分析,指出原有的辨识飞行品质参数方法存在的问题,并提出新的解决方案,即首先对原始模型进行转换,得到一组可辨识性强的模型,然后综合引用极大似然方法和Ｅｘｔｅｍｅ单变量寻优方法辨识新的模型及参数,最后利用双步ＱＲ分解技术求出与原始模型中的相对应的。物理意义明确的飞行品质参数,另外,针对现代主动控制飞机时间延迟τ较大的特点,提出了一种新的处理时间延迟环节ｅ＾－τ     

基于CFD技术的飞机风挡加温系统热载荷计算

热载荷计算是飞机风挡加温系统设计的基础。选取不同的飞行条件和结冰气象,基于CFD技术,通过外流场和水滴撞击特性计算得到了风挡外表面的压力分布、热流密度、对流换热系数以及局部水收集系数,最终确定了风挡防冰和防雾热载荷,并对仿真结果进行了瞬态校核。经验证表明,本文使用的计算方法合理,可以应用于工程设计。     

Disturbance observer based model predictive control for accurate atmospheric entry of spacecraft

Facing the complex aerodynamic environment of Mars atmosphere, a composite atmospheric entry trajectory tracking strategy is investigated in this paper. External disturbances, initial states uncertainties and aerodynamic parameters uncertainties are the main problems. The composite strategy is designed to solve these problems and improve the accuracy of Mars atmospheric entry. This strategy includes a model predictive control for optimized trajectory tracking performance, as well as a disturbance observer based feedforward compensation for external disturbances and uncertainties attenuation. 500-run Monte Carlo simulations show that the proposed composite control scheme achieves more precise Mars atmospheric entry (3.8?km parachute deployment point distribution error) than the baseline control scheme (8.4?km) and integral control scheme (5.8?km).     

Evolution of salt finger convection with steady wind shear

In oceanographics situations where salt fingers may be an important mechanism for the transport of heat and salt in the vertical direction, velocity shears may also be present. Salt finger convection is analogous to Bénard convection in that the kinetic energy of the motions is obtained from the potential energy stored in the unstable distribution of a stratifying component. On the basis of the thermal analogy it is of interest to discover whether salt fingers are converted into two-dimensional sheets by wind shear, and how the vertical fluxes of heat and salt are changed by wind shear. Salt finger convection under the effect of steady wind shear is theoretically examined in this paper. The evolution of instability developing in the presence of a vertical density gradient disturbance and the horizontal Couette flow is considered near the onset of salt fingers under a moderate rate of shear. We use velocity as the basic variable and solve the pressure Poisson equation in terms of the associated Green function. Growth competition between the longitudinal rolls (LR) and the transverse rolls (TR), whose axes are, respectively, in the direction parallel to and perpendicular to the Couette flow, is investigated by the weakly nonlinear analysis of coupled-mode equations. The results show that the TR mode is stable under a small wind shear and the LR mode is stable for a higher wind shear.     

磁带机运转对星载CCD相机成像的影响

利用Ｌａｇｒａｎｇｅ方程,建立了磁带轮转动和卫星姿态振动相互影响的仿真模型,并用数值计算方法计算了卫星的姿态振动,仿真分析了对星载线阵ＣＣＤ成像质量的影响。     

卫星通信的产业化

回顾了中国发展卫星通信的简要历史,介绍了中国卫星通信的现状和作用。在调查国内用户需求的基础上,预测了１９８８－２００２年国内用户对卫星通信转发器需要的数量。     

型号研制的矩阵管理与两师系统

讨论了卫星型号研制中组织机构体制的深化改革问题;介绍了多型号通常采用的矩阵管理体制;论述了两师系统在矩阵管理中的作用;提出了加强两师系统的措施。     

1958年7月8日磁暴的电离层响应

本文用遍布全球的52个电离层垂测台站资料,研究1958年7月8日磁暴期间全球电离层扰动的发展变化;各扇区的响应特性;扰动的传播轨迹及速度等。获得以下结果:1.几大扇区的电离层扰动始于南北两极,美洲扇区除具这一特征外,其赤道地区在磁暴急始后不久,出现一个扰动中心,邻近区域的扰动受其控制。2.扰动由高纬向低纬发展,由扰动中心向外传播。3.扰动峰面几乎与地磁力线垂直,即扰动沿磁力线方向发展,其传播速度大约在150—600m/s范围。