Aero-optical wavefront measurement technique based on BOS and its applications

A collimated light beam will be refracted if it propagates through a flow-field with index-of-refraction variations,and its wavefront will be distorted.If we measure the deflection angle of the light beam,the gradient of the wavefront can be obtained using the Malus law,and the wavefront aberration can be computed with a reconstruction algorithm.Two characteristics of background oriented schlieren(BOS) are conducive to wavefront aberration measurement:BOS can be used to measure the deflection angle of a light beam by measuring the displacement field between the reference image and the experiment image.Moreover,in a BOS system of Schlieren mode,only the ray perpendicular to the background image can be captured with a camera.This is helpful to measure wavefront aberrations that occur after a planar wavefront has passed through the flow-field.Based on these characteristics of BOS of Schlieren mode,a new wavefront measurement technique,which is called the BOS-based wavefront technique(BOS-WT),is proposed in this paper.It works by constructing the relationship between the displacement of the background image and the aero-optical wavefront gradient and uses the Southwell wavefront reconstruction algorithm.A BOS-WT system was assembled,and its temporal resolution was found to be 6 ns,and its temporal-correlation resolution reached 0.2 μs.A BOS-WT can measure the time-correlation transient wavefront quantitatively.It is simple and easy to operate.In this paper,we also present a study of the aero-optical performance of supersonic mixing layer based on our BOS-WT transient wavefronts at an interval of 5 μs.The results showed the wavefront was transient and distorted after it had passed through the mixing layer.Through the analysis of the data at the 5 μs interval,the temporal evolution of wavefront can be obtained.     

一类T_(BOS)~n 唯一路径簇构造与图形特性分析

应用布尔序集关系理论，研究了一类典型Ｔ _ＢＯＳ^ｎ 唯一路径簇的构造与实现方法．同时给出基本图形特性的分析．     

基于Matlab/Stateflow的4AT换挡控制仿真研究

为实现车辆换挡操纵的自动化,文章根据自动变速器双参数换挡规律,运用PID控制理论建立了驾驶员模型,并根据整车各部分数学原型建立了发动机模型、传动模型、车辆模型。在整车模型及其工作原理的基础上,从动力性及经济性2个方面确定了换挡规律,并采用Stateflow有限状态机理论建立换挡逻辑控制模型。在UDDS工况和依照制动优先系统(Brake Override System,简称BOS)建立的车辆行驶特殊工况下进行仿真,并与自动变速器台架试验结果进行对比,结果表明,该自动变速器模型,能严格按照换挡规律换挡。     

有耗目标的电磁相似性及矩形涂覆平板RCS的缩比关系

把Sinclair关于理想导体目标的经典电磁相似理论推广到目标包含有耗材料的电磁系统,建立了有耗目标严格的电磁相似理论.文中以涂覆吸波材料的矩形导电平板为例,研究了缩比模型中的有耗吸波材料在不满足物理相似条件时目标雷达截面RCS的缩比关系.     

构建工作流驱动的符合J2EE标准的广东省民政业务支持系统

叙述了用工作流和JAVA技术开发广东省民政业务统一软件的架构设计思想,开发出一个流程驱动的主要基于配置开发的民政业务支持系统(BOS).