反射面型天线结构多工况离散变量优化设计

根据反射面型天线结构受载和工作状态的复杂性，以及总有一些变量只能按离散变量处理，建立了符合工程结构的反射面型天线结构多工况离散变量优化设计数学模型，编制了一套具有一定通用性及工程实用价值的优化设计软件，并用其对八米反射面型天线进行了优化计算，取得了比较满意的效果。     

航天器动力学技术的发展和挑战

本文首先简要回顾了中国航天器动力学分析设计技术的研究发展和工程应用;然后,阐述了21世纪初期中国复杂航天器的发展对航天器动力学分析设计技术提出的新要求,重点分析了在动力学分析、仿真、优化与试验方面必须突破和解决的若干关键技术;最后,对中国航天器动力学分析设计技术的发展目标和前景作了展望。     

飞航导弹动力装置的预测控制设计

在大空域内实现对于飞航导弹巡航马赫数的有效控制是一个迫切需要解决的问题。首先通过机理分析,确定了连续形式的导弹 动力装置线性化简化数学模型,然后通过一种具有强鲁棒性的递推阻尼最小二乘参数辨识算法,对于它的离散模型特征参数进行实时估计,最后以这个离散模型为基础通过设计预测控制得到了燃油调节规律。通过与传统PID调节方法的比较,显示了这种方法在工况大范围变化的情况下,能够保持马赫数调节的高精度与快速性,改善了动态品质,具有很强的鲁棒性与适应性。     

论微电子机械系统MEMS

简介了微电子机械系统MEMS的基本概念、构成及显著特点 ,并对微电子机械系统的典型器件如传感器 ,执行器等作了介绍与分析 ,提出了微系统之间要研究的问题 ;探讨了微电子机械系统的发展应用前景     

Validation of numerical prediction of dynamic derivatives: The DLR-F12 and the Transcruiser test cases

The dynamic derivatives are widely used in linear aerodynamic models in order to determine the flying qualities of an aircraft: the ability to predict them reliably, quickly and sufficiently early in the design process is vital in order to avoid late and costly component redesigns. This paper describes experimental and computational research dealing with the determination of dynamic derivatives carried out within the FP6 European project SimSAC. Numerical and experimental results are compared for two aircraft configurations: a generic civil transport aircraft, wing-fuselage-tail configuration called the DLR-F12 and a generic Transonic CRuiser, which is a canard configuration. Static and dynamic wind tunnel tests have been carried out for both configurations and are briefly described within this paper. The data generated for both the DLR-F12 and TCR configurations include force and pressure coefficients obtained during small amplitude pitch, roll and yaw oscillations while the data for the TCR configuration also include large amplitude oscillations, in order to investigate the dynamic effects on nonlinear aerodynamic characteristics. In addition, dynamic derivatives have been determined for both configurations with a large panel of tools, from linear aerodynamic (Vortex Lattice Methods) to CFD. This work confirms that an increase in fidelity level enables the dynamic derivatives to be calculated more accurately. Linear aerodynamics tools are shown to give satisfactory results but are very sensitive to the geometry/mesh input data. Although all the quasi-steady CFD approaches give comparable results (robustness) for steady dynamic derivatives, they do not allow the prediction of unsteady components for the dynamic derivatives (angular derivatives with respect to time): this can be done with either a fully unsteady approach i.e. with a time-marching scheme or with frequency domain solvers, both of which provide comparable results for the DLR-F12 test case. As far as the canard configuration is concerned, strong limitations for the linear aerodynamic tools are observed. A key aspect of this work are the acceleration techniques developed for CFD methods, which allow the computational time to be dramatically reduced while providing comparable results.     

Thermal stability improvement of sprayable fast-responding pressure-sensitive paint for measurement above 100 °C

The thermal stability of sprayable fast-responding Pressure-Sensitive Paint (fast PSP) was investigated to explore the possibility for application in turbomachinery and hypersonic research with temperature above 100 °C. The first part of the study focused on a widely-used Polymer Ceramic PSP (PC-PSP). The effects of thermal degradation on its key sensing properties, including luminescent intensity, pressure sensitivity and response time, were examined for a temperature range from 60 to 100 °C. Severe degradation in intensity and pressure sensitivity was found as temperature reached 70 °C or higher, which would cause failure of PSP application in these conditions. Subsequently, a fast-responding Mesoporous-Particle PSP (MP-PSP) was developed which did not show degradation effects until 140 °C. The greatly improved thermal stability of MP-PSP was attributed to: selection of polymer with higher glass transition temperature (polystyrene) to delay the saturation effect of oxygen quenching as temperature increased; porous and hollow structure of particles for luminophore deposition that minimizes polymer–luminophore interaction. This new paint formulation has significantly raised the upper temperature limit of fast PSP and offers more opportunities for applications in harsh environment.     

Impact of reduced frequency on the time lag in pressure distribution over a supercritical airfoil in a pitch-pause-return motion

Effects of reduced frequency, stop angle, and pause duration have been studied on a thin supercritical airfoil undergoing a pitch-pause-return motion, which is one of the classic maneuvers introduced by the AIAA Fluid Dynamics Technical Committee. Experiments were conducted in a low-speed wind tunnel at both a constant mean angle of attack and an oscillation amplitude with a reduced frequency ranging from 0.01 to 0.12. The desired stop angles of the airfoil were set to occur during the upstroke motion. The unsteady pressure distribution on the airfoil was measured for below, near, and beyond static stall conditions. Results showed that the reduced frequency and stop angle were the dominant contributors to the time lag in the flowfield. For stop angles in both below- and post-stall regions, the time for the flowfield to reach its steady state conditions, known as the time lag, decreased as the reduced frequency was increased. However, in the static-stall region and for a certain value of reduced frequency, a resonance phenomenon was observed, and a minimum time lag was achieved. The pressure distribution in this condition was shown to be highly influenced by this phenomenon.     

动态相位噪声测试系统

介绍了在振动、强声噪环境下,动态相位噪声测试系统的原理、构成和数据处理过程,并分析了测试结果的准确度。     

《蝇王》象征体系的构建

《蝇王》是当代英国著名小说家威廉.戈尔丁的第一部小说。戈尔丁以象征手法和寓言为主要叙述技巧来表现“人心的黑暗”这一主题。主要从背景、人物以及实物这3个方面分析象征主义手法在《蝇王》中的运用,正是通过这种无处不在的象征,戈尔丁向人们揭示出社会的一切弊端无不是由人的邪恶本性造成,并希望现代人能认识自己的本性,有意识地抑制本性中的黑暗面,起到了警世的作用。