Trajectory and attitude deviations for internal store separation due to unsteady and quasi-steady test method

The deviations of trajectory and attitude angle for internal store separation are evaluated by two wind tunnel test methods. One is the Freedrop Test(FDT), which is known as unsteady and time-dependent method of scaled model. The other is the Captive Trajectory System(CTS) test,which is usually regarded as a quasi-steady and time-averaged test technology. The result shows that there is a streamwise adverse pressure gradient on the cavity resulting in a nose-up pitching moment coefficient(>0) ...     

三角翼大攻角绕流数值模拟研究

采用Harten-Yee的二阶精度隐式TVD格式对N-S方程进行数值模拟,研究了后掠角为65°和70°的三角翼绕流的流场特性。计算结果表明：TVD格式中限制器函数的选取对于三角翼绕流结构的计算结果具有较重要的影响。结合张涵信的旋涡定性分析理论对旋涡的发展过程进行研究,此外,还对二次涡破裂现象和网格分布影响等问题进行了探讨。     

液晶显示方法研究管内马赫数4拟似冲击波流动

在一个压力-真空型超声速风洞中, 剪切应力敏感的液晶表面流动显示技术被用来研究方管内马赫数4拟似冲击波的超声速流动.实验是在日本室兰工业大学的超声速风洞中进行.它提供了关于测试表面流动结构的定性信息,诸如湍流边界层分离和再附, 以及边界层流动的维数等.液晶显示结果与纹影实验照片和油膜方法进行比较,证实了它是一种非常有效的表面流动显示工具.     

Intrinsic component filtering for fault diagnosis of rotating machinery

Fault diagnosis of rotating machinery has always drawn wide attention. In this paper, Intrinsic Component Filtering (ICF), which achieves population sparsity and lifetime consistency using two constraints: $l_{1/2}$ norm of column features and $l_{3/2}$ -norm of row features, is proposed for the machinery fault diagnosis. ICF can be used as a feature learning algorithm, and the learned features can be fed into the classification to achieve the automatic fault classification. ICF can also be used as a filter training method to extract and separate weak fault components from the noise signals without any prior experience. Simulated and experimental signals of bearing fault are used to validate the performance of ICF. The results confirm that ICF performs superior in three fault diagnosis fields including intelligent fault diagnosis, weak signature detection and compound fault separation.     

船只目标三维转动对SAR成像影响的定量分析

在分析船只三维转动（横滚、俯仰、偏航）对合成孔径雷达（Synthetic Aperture Radar,SAR）成像质量的影响方面,现有文献只考虑了仅存在一维转动时的影响,未考虑三维转动同时存在时对SAR成像质量的影响。另外,现有文献主要基于船只转动对船只散射点瞬时多普勒频率的影响进行分析,并未真正与对SAR图像质量的影响关联起来。本文推导了适用于船只存在三种一维转动、同时存在三维转动时的SAR图像二维时域表达式,以及散射点方位向坐标的表达式。在上述表达式的基础上,通过分析船只上的散射点在SAR图像中的偏移情况,扩展到分析船只整体在SAR图像中的形变情况;通过分析一维转动对SAR成像的影响,扩展到分析三维转动同时存在时对SAR成像的影响。研究表明：船只三维转动引入了包络误差和相位误差,导致SAR图像中散射点模糊并在方位向偏移,且不同散射点的偏移量不同,从而使船只形状发生畸变。仿真结果验证了所推导表达式的准确性及理论分析的正确性。     

Effects of sweep angles on turbulent separation behaviors induced by blunt fin

An experimental study was conducted on turbulent separation behaviors induced by blunt fins with different sweep angles at Mach number 6.0. The Nano-particle based Planar Laser Scattering technique(NPLS) was applied to visualize the flowfield, complemented by pressure tests.Sweep angles of the fins were 10°, 20°,...,60°, with the same leading edge diameter of 10 mm. Fine structures of the interference flowfield induced by blunt fins have been obtained, including the shock systems and vortexes. I...     

展向射流控制机翼前缘涡的机理及其应用

旋涡和流动分离的控制一直是空气动力学研究的一个重要。研究表明展向吹气是控制机翼上旋裂和流动分离的一种十分有效的气动措施。     

动态测量的不确定度分离原理

对动态测量系统进行建模 ,提出了动态测量不确定度的分离原理 ,将测量不确定度的贡献分为内部不确定度和外部不确定度两类 ,指出二者可以分别分析计算并符合不确定度的传播规律 ,该原理具有理论上和工程上的实用价值。     

一种用于超高速撞击实验的新型弹丸弹托分离技术

文章自主研发了一种新型的气动力弹丸与弹托分离技术。在北京卫星环境工程研究所的φ18mm二级轻气炮上应用该技术在3~7km/s的速度内可以成功分离直径在3～10mm的弹丸,弹托分离非常干净,分离成功率达100%。对比分析显示,该技术分离效果优于目前公开报道的其它技术。     

分布式天线接收的混合通信信号盲分离

在非协作的通信环境中,由分布式接收天线构成的“虚拟天线阵列”信号模型与常规的盲源分离的典型模型有明显差异,导致现有的一些盲源分离的方法和算法难以适用于分布式天线接收的混合通信信号的分离。利用各源信号之间的统计独立性和通信信号的循环平稳性,提出了一种适合于分布式天线接收的混合通信信号盲分离的思想和实现方法。仿真实验表明,提出的方法能有效地分离出源信号。