基于3D GIS无人直升机地面站系统软件设计与实现

为了实现无人直升机地面站系统的空间数据处理、三维可视化和导航的功能,提出了基于3D GIS无人直升机地面站系统软件设计及其实现的方法.首先对无人直升机的整体系统框架进行说明,然后对地面站系统的软件框架设计和各个功能模块做了详细的分析,在此基础上重点分析了利用World Wind Java软件开发包来实现3D GIS导航的过程.整个地面站软件系统使用Java语言编写,嵌入3DGIS.最后以实例证明了该地面站系统软件的可行性,并且具有良好的可移植性和可扩充性.     

由单幅图像重构三轴试样三维变形

针对岩土三轴试验的土样变形测量需要进行三维测量这个难题,提出了新的由单幅图像进行三维重构方法--结构标记法,即利用三维试样标记的各点相对于摄像机的物距不同而造成成像位置改变的原理,从二维图像中提取出了三维信息,实现了三维重构.利用双目或多目图像进行三维重构是比较常见的方法.但是这种方法受到光照条件、噪声干扰、景物几何形状和畸变、表面物理特性以及摄像机特性等因素的严重干扰,而且所需的试验设备也非常复杂.为了克服这些困难,可以采用单幅图像来代替多目图像进行三维重构.给出了计算结果,并说明了这些结果的合理性.     

基于ARM的嵌入式无线视频监控系统

介绍了一种基于ARM9高速嵌入式处理器和H.264高效压缩算法的嵌入式3G无线视频监控系统.分析了系统的总体结构、硬件结构,并重点阐述了系统软件的设计与实现.实验结果表明,该系统可以达到25帧/秒CIF图像(320×240),实现了视频流畅传输.     

基于S3C2440和Windows CE5.0的嵌入式设备休眠唤醒技术研究

就休眠唤醒技术实现过程中的难点进行了深入研究,并针对S3C2440开发板提出了两种可行的低功耗休眠模式唤醒实现方法:外部中断唤醒和RTC中断唤醒.将这两种方法应用于一款基于S3C2440和WindowsCE 5.0的嵌入式智能巡检分析诊断仪,仪器运行稳定、效果理想.     

基于C8051F340控制的TD直放站控制方案设计

介绍一种基于C8051F340快速单片机控制的直放站设计;采用GPS同步法,按时隙功率控制,自动增益控制AGC环路,系统的非线性指标良好、抗干扰性强、可靠性高.比以功率检测的同步方法和基于特征窗搜索的同步方法实现简单,应用范围更广,可用于任何无线直放站应用场合,特别适用于干放及无线射频交换场合.     

A goodness-of-fit test for Archimedean copula models in the presence of right censoring

A goodness-of-fit testing procedure for Archimedean copula (AC) models is developed based on right-censored data. The proposed approach extends an existing method, which is suitable for the Clayton model, to general AC models. Asymptotic properties of the proposed test statistics under the true model assumption are derived. Simulation analysis shows that the proposed test has reasonable performance. Finally, two real data examples are analyzed for illustrative purposes.     

A portable stereo vision system for whole body surface imaging

This paper presents a whole body surface imaging system based on stereo vision technology. We have adopted a compact and economical configuration which involves only four stereo units to image the frontal and rear sides of the body. The success of the system depends on a stereo matching process that can effectively segment the body from the background in addition to recovering sufficient geometric details. For this purpose, we have developed a novel sub-pixel, dense stereo matching algorithm which includes two major phases. In the first phase, the foreground is accurately segmented with the help of a predefined virtual interface in the disparity space image, and a coarse disparity map is generated with block matching. In the second phase, local least squares matching is performed in combination with global optimization within a regularization framework, so as to ensure both accuracy and reliability. Our experimental results show that the system can realistically capture smooth and complete whole body shapes with high accuracy.     

A parallel direct solver for the self-adaptive hp Finite Element Method

In this paper we present a new parallel multi-frontal direct solver, dedicated for the hp Finite Element Method (hp-FEM). The self-adaptive hp-FEM generates in a fully automatic mode, a sequence of hp-meshes delivering exponential convergence of the error with respect to the number of degrees of freedom (d.o.f.) as well as the CPU time, by performing a sequence of hp refinements starting from an arbitrary initial mesh. The solver constructs an initial elimination tree for an arbitrary initial mesh, and expands the elimination tree each time the mesh is refined. This allows us to keep track of the order of elimination for the solver. The solver also minimizes the memory usage, by de-allocating partial LU factorizations computed during the elimination stage of the solver, and recomputes them for the backward substitution stage, by utilizing only about 10% of the computational time necessary for the original computations. The solver has been tested on 3D Direct Current (DC) borehole resistivity measurement simulations problems. We measure the execution time and memory usage of the solver over a large regular mesh with 1.5 million degrees of freedom as well as on the highly non-regular mesh, generated by the self-adaptive hp$hp$-FEM, with finite elements of various sizes and polynomial orders of approximation varying from p=1$p=1$ to p=9$p=9$. From the presented experiments it follows that the parallel solver scales well up to the maximum number of utilized processors. The limit for the solver scalability is the maximum sequential part of the algorithm: the computations of the partial LU factorizations over the longest path, coming from the root of the elimination tree down to the deepest leaf.     

Connecting the 3D DGS Calques3D with the CAS Maple

Many (2D) Dynamic Geometry Systems (DGSs) are able to export numeric coordinates and equations with numeric coefficients to Computer Algebra Systems (CASs). Moreover, different approaches and systems that link (2D) DGSs with CASs, so that symbolic coordinates and equations with symbolic coefficients can be exported from the DGS to the CAS, already exist. Although the 3D DGS Calques3D can export numeric coordinates and equations with numeric coefficients to Maple and Mathematica, it cannot export symbolic coordinates and equations with symbolic coefficients. A connection between the 3D DGS Calques3D and the CAS Maple, that can handle symbolic coordinates and equations with symbolic coefficients, is presented here. Its main interest is to provide a convenient time-saving way to explore problems and directly obtain both algebraic and numeric data when dealing with a 3D extension of “ruler and compass geometry”. This link has not only educational purposes but mathematical ones, like mechanical theorem proving in geometry, geometric discovery (hypotheses completion), geometric loci finding… As far as we know, there is no comparable “symbolic” link in the 3D case, except the prototype 3D-LD (restricted to determining algebraic surfaces as geometric loci).     

关于3G通信网络安全问题的探讨

着重研究了第三代移动通信系统的安全性,首先介绍了3G的安全要求、安全体系结构及其面临的安全隐患,然后详细探讨了3G网络的安全保障策略,对于中国将要广泛开展的3G系统及工程的建设具有特别重要的意义。