卫星干涉高光谱遥感图像序列差值压缩编码

根据干涉高光谱图像的成像特点和卫星遥感图像压缩编码系统要求，提出了一种新的卫星干涉高光谱图像序列压缩算法．新算法利用干涉成像光谱仪推扫成像特点提出了一种低存储量，帧间小波域匹配的图像序列压缩方案，提高图像质量3—4dB．算法首先通过小波域匹配算法检测出相邻图像之间的推扫位移量并移位求得两帧的最佳差值图像，然后对差值图像进行静止图像EBCOT压缩编码，从而提高总体编码效率．该算法具有与单帧图像编码算法相当的复杂度，只需要对当前图像与模板的差值图像进行基于小波变换的编码，避免了目前基于三维小波变换的编码算法对系统大存储量要求以及编码延时大的缺陷．仿真结果表明，本算法针对干涉高光谱图像编码，可获得比基于三维小波变换的算法相当甚至更好的效果，并且大大降低了编码延时．     

High-resolution simulation for rotorcraft aerodynamics in hovering and vertical descending flight using a hybrid method

A high-resolution simulation tool for rotorcraft aerodynamics is developed by coupling CFD with a Vorticity Transport Model (VTM). An Eulerian-based CFD module is used to model the blade near body flowfield, and a Lagrangian-based VTM module is employed for vortex tracking in the far wake. The coupling procedure is implemented by transmitting vortex sources to the VTM module and feeding boundary conditions back to the CFD module. The presented CFD/VTM hybrid solver is firstly validated by hover cases of three different rotor configurations. Simulation results, including the blade surface pressure distribution, rotor downwash, and hover figure of merit, exhibit favorable correlations with available experimental data. Then, a rotor operated in vertical descending flight with a fixed collective pitch is investigated. It is shown that the CFD/VTM coupling method is suitable for rotor wake simulation. Wake instabilities (far wake breakdown in hover and toroidal wake pattern in the vortex ring state) are successfully demonstrated with a moderate computational cost.     

我国航空运输需求价格弹性测算

根据经济学理论,同时结合我国航空运输的特点,通过引入我国GDP和我国航空运输每运输吨公里收入两个变量,利用线性回归分析的方法建立了我国航空运输需求函数,并根据需求函数绘制了我国航空运输需求曲线,然后根据需求函数和需求曲线测算了我国航空运输需求价格弹性值。最后,对本研究需要改进的方面进行了分析和总结。     

扇环形截面弯曲管道内的粘性流动

本文利用涡量－流函数法系统地研究了扇环形截面弯曲管道内的二次流动，计算结果表明了采用控制体积积分法对涡量－流函数方程进行离散来求解弯曲管道内粘性流动问题是成功的，这样可以避免对压力项的处理；对所得结果的分析揭示了该二次流动不仅受雷诺数和曲率影响，而且扇形中心角、内外径之比对该流动的影响也是显著的。     

基于进离场流量和冲突发生位置的扇区规划

随着空中交通流量的日渐增大，空域结构及交通流分布的不合理性导致空中交通管制与飞行安全存在着一定的隐患。鉴于机场进近区是限制空域运行能力的主要瓶颈，针对如何提高空域资源利用率从而提升空域容量进行了进近区扇区规划，提出了考虑飞行流量、冲突发生的位置以及空域运行情况等因素建立的扇区容量均衡模型，利用霍夫曼编码原理进一步找到了扇区边界，并验证了方法的科学性和合理性。     

Macroscopic Transport Large-scale advection, turbulent diffusion, wave transport

While the solar convection zone is very well mixed by its turbulent motions, chemical composition gradients build up in the radiative interior due to microscopic diffusion and settling, and to nuclear burning. Standard models, which ignore any type of macroscopic transport, cannot explain the depletion of lithium in solar-type stars, as they evolve; neither do they account for the observed profile of molecular weight at the base of the solar convection zone. Such macroscopic transport can be achieved through thermally driven meridian currents, through turbulent diffusion generated by differential rotation and possibly through gravity waves. These processes transport also angular momentum, and therefore the internal rotation profile of the Sun provides a crucial test for their relative importance. So does also the behavior of tidally locked binaries, which appear to destroy less lithium than single stars of the same mass. This revised version was published online in June 2006 with corrections to the Cover Date.     

一种基于控制流的复杂系统故障树自动建树方法

复杂系统中故障以控制流的形式传递,其输出变量偏差于正常输出变量可用不同的控制流描述,根据控制流进行故障树的自动建立,可设计四个模块将变量传递关系用数据表示出来.首先,定义各种数据结构把控制系统中各种变量量化在具体的数据当中,然后通过识别控制环算法和故障树自动建树算法建树,最后,把连接好的故障树数据转化为二叉树数据结构,用可视化语言把故障树显现出来.     

工业远程监控系统实施新方案

近期远程监控系统在工业中逐步推广,针对工业系统的特点和工业网络的实际情况,在原有工业系统的基础上,增加现场设备区域的图像监控和数据传输功能,提出了一种工业远程监控系统实施方案.本文论述了该系统的结构、原理及实现方法,经具体实施证明,本文提出的方案已基本能够满足一个通用的基于公用网络的远程视频监控系统的要求,体现了较重要的理论价值和很强的工程实用价值.     

Joint Iterative Decoding for Network-Coding-Based Multisource LDPC-Coded Cooperative MIMO

A network-coding-based multisource LDPC-coded cooperative MIMO scheme is proposed,where multiple sources transmit their messages to the destination with the assistance from a single relay.The relay cooperates with multiple sources simultaneously via network-coding.It avoids the issues of imperfect frequency/timing synchronization and large transmission delay which may be introduced by frequency-division multiple access(FDMA)/code-division multiple access(CDMA)and time-division multiple access(TDMA)manners.The proposed joint″Min-Sum″iterative decoding is effectively carried out in the destination.Such a decoding algorithm agrees with the introduced equivalent joint Tanner graph which can be used to fully characterize LDPC codes employed by the sources and relay.Theoretical analysis and numerical simulation show that the proposed scheme with joint iterative decoding can achieve significant cooperation diversity gain.Furthermore,for the relay,compared with the cascade scheme,the proposed scheme has much lower complexity of LDPC-encoding and is easier to be implemented in the hardware with similar bit error rate(BER)performance.     

基于Lagrange方法的单旋翼飞行器动力学建模

为了进行微小型单旋翼飞行器的动力学建模,通过建立多个坐标系来反映各部分间的相对运动.首先,利用坐标变换得到位置、速度及加速度等向量,并代入拉格朗日方程得到运动学模型;然后,对模型进行数值求解,得到飞行器的姿态响应.仿真结果表明,飞行器定点盘旋时合外力为零,能量保持不变;爬升或前飞时有非保守力做正功,能量增大.