巨型水电站孤岛试验期间AVC电压波动的解决

本文首先分析国内典型的AVC的一般配置、控制策略和控制原理,针对巨型水电站孤岛试验期间的AVC控制的复杂工况进行阐述,对出现的AVC电压波动的情况进行分析,并对采用的解决方案进行介绍,为今后类似电站的孤岛运行期间的AVC电压控制提供一些参考建议。     

基于FPGA的CAVLC编解码器设计与实现

H．264标准在基本档次和扩展档次中采用CAVLC熵编码，完成对变换系数残差块的编码。提出一种基于FPGA的H．264标准的CAVLC编解码器，程序代码用verilog硬件描述语言编写，并在QuartusⅡ中进行了仿真验证，可以实现对每个残差块数据的编解码并将其按照宏块光栅扫描的顺序输出到存储器，因此适合于嵌入在最终的码流中。仿真结果表明此CAVLC编解码器达到H．264标准中基本档次和扩展档次level3．0的性能要求。     

Grouped Approach for the Design of H.264/AVC Motion Estimation Architectures

This letter presents a novel approach for organizing computational resources into groups within H.264/AVC motion estimation architectures, leading to reductions of up to 75% in the equivalent gate count with respect to state‐of‐the‐art designs.     

项重写系统的并行实现方案

项重写系统的并行归约可以提高归约的效率，在无共享内存的Ｔｒａｎｓｐｕｔｅｒ网络上实现时要考虑任务的分配，项的拼装，归约任务的控制等问题，其中怎么样减少机间的机内进程的通信慢提高系统效果的关键。本文从控制方式角度讨论在不同拓扑结构的Ｔｒａｎｓｐｕｔｅｒ网络上实现项重写系统的方案，重点介绍基于树形结构下的控制方法，进程安排和通讯形式。     

H.264/AVC可伸缩扩展集

可伸缩视频编码是目前国际上研究的热点。联合视频组（JVT）在过去的一年中围绕SVC展开了大量的研究工作，提出了作为H.264／AVC扩展集的SVC方案。实现了时间、空间和质量（SNR）的可伸缩性。本文介绍H.264／AVC可伸缩扩展集的基本结构和技术要点。     

Nonterminating Rewritings with Head Boundedness

We define here the concept of head boundedness,head normal form and head confluence of term rewriting systems that allow infinite derivation.Head confluence iw weaker than confluence,but sufficient to guarantee the correctness of lazy implementations of equational logic programming languages.Then we prove several results.First,if a left-linear system is locally confluent and head-bounded.then it is head-confluent.Second,head-confluent and head-bounded systems have the heau Church-Rosser property.Last,if an orthogonal system is head-terminating,then it is head-bounded.These results can be applied to generalize equational logic programming languages.     

三峡水电站机组无功调节原理及其运行情况分析

对三峡水电站励磁调节器及其无功调节原理进行了简要介绍，并就三峡水电站机组无功调节环节层次和AVC投退条件进行了详细叙述。针对三峡水电站机组运行中出现的两次无功和电压异常现象，进行了定性分析并给出结论和建议。     

H.264/AVC帧内4×4块预测模式判别的改进算法

H.264提供了4×4的亮度块帧内预测,其共有9种预测模式.在判断其预测模式中要求4×4块的每种预测模式都要判断,因此计算复杂度很高.有效减少4×4块预测模式的判断次数,在实时视频编码过程中很有价值.基于此,提出了一种帧内4×4块预测模式判断提前退出的优化算法,并对其进行了试验,得到了很好的效果.     

Binary rewriting and call interception for efficient runtime protection against buffer overflows

Buffer overflow vulnerabilities are one of the most commonly and widely exploited security vulnerabilities in programs. Most existing solutions for avoiding buffer overflows are either inadequate, inefficient or incompatible with existing code. In this paper, we present a novel approach for transparent and efficient runtime protection against buffer overflows. The approach is implemented by two tools: Type Information Extractor and Depositor (TIED) and LibsafePlus. TIED is first used on a binary executable or shared library file to extract type information from the debugging information inserted in the file by the compiler and reinsert it in the file as a data structure available at runtime. LibsafePlus is a shared library that is preloaded when the program is run. LibsafePlus intercepts unsafe C library calls such as strcpy and uses the type information made available by TIED at runtime to determine whether it would be ‘safe’ to carry out the operation. With our simple design we are able to protect most applications with a performance overhead of less than 10%. Copyright © 2006 John Wiley & Sons, Ltd.