面向巡防系统的混沌视频加密技术研究

巡防系统具有远程视频图像传输的功能,考虑到视频信息传输过程中存在被恶意盗取造成信息严重缺失的情况,在视频传输前需对视频做加密处理。结合H.264视频压缩编码,采用Logistic混沌序列在CAVLC熵编码阶段对视频进行选择性加密,实现了加密与视频压缩编码兼容。并在Visual Studio 2013中完成了基于Logistic混沌视频加密的仿真,在MATLAB中通过计算视频图像加密前后的PSNR、SSIM及RGB直方图,分析了Logistic混沌视频加密性能。     

触摸屏在S3C44b0上的应用

本文以S3C44b0为平台给出了触摸屏的概念、工作原理、接口电路和软件程序;改进了软件滤波的实现方法,该算法使用C语言,可移植到任何操作系统的触摸屏驱动程序中.     

A methodology for designing proof rules for fair parallel programs

We propose a methodology for designing sound and complete proof systems for proving progress properties of parallel programs under various fairness assumptions. Our methodology begins with a branching time temporal logic formula (CTL^*) formula that expresses progress under a fairness assumption. The next step obtains an equivalent fixpoint characterization of this CTL^* formula in theh2573u61256p3544/xxlarge956.gif" alt="mgr" align="MIDDLE" BORDER="0">-calculus. The final step uses the fixpoint characterizations to extract proof systems for proving progress under the fairness constraint. The methodology guarantees that the proof rules so obtained are sound and relatively complete in the sense of Cook.     

一种面向数据密集型应用的并行程序执行模型

随着各领域需要处理的数据量越来越大,数据密集型应用也变得越来越被重视.该文提出一种包含数据访存层次和访存冲突等信息的新并行程序执行模型PSRAM(h).针对数据密集型应用以访存为主的特点,PSRAM(h)模型将程序执行时间简化为访存时间,通过分析各程序子段的访存层次和数量来预测串行程序的执行时间,进而通过使用各线程执行时间的最大值来预测并行程序的执行时间.使用PSRAM(h)模型下对最典型的数据密集型应用矩阵向量乘进行分析,在龙芯3A处理器和Intel Xeon E5520处理器两个平台上的测试结果表明,PSRAM(h)模型分析结果与实测结果大部分情况下误差小于20%.由此可见,针对数据密集型应用,PSRAM(h)不但可以给出程序执行时间的下限,还可以有效的预测程序的执行时间.     

On a quasiorder on the class of monounary algebras

In the paper we introduce a relation h3/MediaObjects/s00500-005-0520-xflb1.gif" alt="MediaObjects/s00500-005-0520-xflb1.gif" align="middle"> on the class of monounary algebras h3/MediaObjects/s00500-005-0520-xflb2.gif" alt="MediaObjects/s00500-005-0520-xflb2.gif" align="middle"> by means of h3/MediaObjects/s00500-005-0520-xflb3.gif" alt="MediaObjects/s00500-005-0520-xflb3.gif" align="middle">-homomorphisms. It is a quasiorder. We take a subclass h3/MediaObjects/s00500-005-0520-xflb4.gif" alt="MediaObjects/s00500-005-0520-xflb4.gif" align="middle"> of h3/MediaObjects/s00500-005-0520-xflb2.gif" alt="MediaObjects/s00500-005-0520-xflb2.gif" align="middle"> containing monounary algebras h3/MediaObjects/s00500-005-0520-xflb5.gif" alt="MediaObjects/s00500-005-0520-xflb5.gif" align="middle"> satisfying the property h3/MediaObjects/s00500-005-0520-xflb6.gif" alt="MediaObjects/s00500-005-0520-xflb6.gif" align="middle"> We characterize algebras in h3/MediaObjects/s00500-005-0520-xflb4.gif" alt="MediaObjects/s00500-005-0520-xflb4.gif" align="middle"> by the notions of a degree and properties of their h3/MediaObjects/s00500-005-0520-xflb3.gif" alt="MediaObjects/s00500-005-0520-xflb3.gif" align="middle">-endomorphisms. We apply the results to finite monounary algebras. Supported by grant VEGA 1/0161/03     

基于嵌入式平台的h.264视频编码器的实现

介绍了基于嵌入式平台PXA255的h.264视频编码器的实现.在描述了视频编码器的硬件结构设计及视频采集软件的实现的基础上,详细介绍了h.264对视频编码标准的一些改进以及基于PXA255结构和ARM汇编指令的h.264编码程序的优化.实验结果表明,优化后的h.264编码程序能够对采集到的视频进行实时编码,该视频编码器运行状态良好.     

ARE法沉积的立方氮化硼薄膜生长过程的研究

采用逆序法研究了通过活性反应离子镀技术沉积在单晶硅 (10 0 )上的c BN膜生长过程。在X射线光电子能谱分析仪上 ,用氩离子剥离c BN膜并进行膜的成分的深度分布及不同刻蚀深度处膜的价态分析 ,用富立叶变换红外透射谱分析不同刻蚀深度处的膜的相结构。结果表明 :在此生长条件下 ,c BN不能在基底上直接成核 ,而是先在基底上形成一层h BN ,然后c BN在其上生长。对这种生长顺序 ,引用c BN膜形成机制的压应力模型给予了解释     

不同频率激励信号下土壤水分传感器性能试验

激励信号频率是影响高频电容式土壤水分传感器性能的重要因素。利用去离子水和2—异丙氧基乙醇(2—isoproxyethanol)或二氧六环(dioxane)2种溶液混合,配制了一系列等效土壤体积含水率为0.9%~51.8%的待测介电溶液来替代土样。从与土壤含水率的函数关系、温度变异性2个方面,分别对激励信号频率为40,50,60,70,80,90,100 MHz的7种土壤水分传感器进行了性能测试与分析。结果表明:7种频率的传感器的输出电压均与土壤体积含水率呈线性负相关,其相关系数R2均大于0.94;激励信号频率不影响传感器输出电压的温度变异性,温差是影响温度变异性的主要因素,其最大变异率均小于4%。试验结果可为设计高频电容式土壤水分传感器时选择激励信号频率提供依据。     

Protein classification by matching and clustering surface graphs

In this paper, we address the problem of comparing and classifying protein surfaces with graph-based methods. Comparison relies on matching surface graphs, extracted from the surfaces by considering concave and convex patches, through a kernelized version of the Softassign graph-matching algorithm. On the other hand, classification is performed by clustering the surface graphs with an EM-like algorithm, also relying on kernelized Softassign, and then calculating the distance of an input surface graph to the closest prototype. We present experiments showing the suitability of kernelized Softassign for both comparing and classifying surface graphs.