影讯简

杰瑞·尤斯曼与玛姬·泰勒夫妇的作品里,任何一个单位元素,云朵、湖水、树木、蜜蜂、斑马……都是我们再熟悉不过的,这些都是构成真实世界的真实元素。但是两位摄影师打乱了物体原本的规律,在视觉上运用真实的元素把我们带入了另外一个内心的“真实”世界。     

基于RS编码的视频差错恢复方法*

为了保证视频质量,可以采用前向纠错编码(FEC)来提高视频数据传输的可靠性。ReedSolomon(RS)码是一种重要的纠错码,它对随机性和突发性错误有极强的纠错能力,广泛应用于数字视频广播(DVB)系统和其他数字通信领域。设计了基于MPEG4视频编码的RS纠错码实验,它可应用于公共交换电话网(PSTN)或DVB系统的视频通信。     

单向信道的信息可靠传输机制研究

提出了两级FEC的机制来解决单向信道的信息可靠传输的问题。数据包级FEC（第一级）通过添加冗余数据包来恢复传输过程中数据包的丢失。比特级FEC（第二级）通过添加冗余比特来纠正数据在传输过程中比特差错。鉴于包头信息是数据包级FEC的关键,提出数据包包头FEC机制来尽量保证包头信息的正确。提出的方案能很好地恢复丢失的数据包,特别是连续数据包的丢失,能很好地纠正比特差错。     

Concurrent multipath transmission combining forward error correction and path interleaving for video streaming

Video streaming is a popular application on next generation networks (NGNs). However, video streaming over NGNs has many challenges due to the high bit error rates of these networks. Forward error correction (FEC) is often applied to improve the quality of video streaming. However, continuous lost packets decrease the recovery performance of FEC protection in NGNs. To disperse continuous lost packets to different FEC blocks, we propose a concurrent multipath transmission that combines FEC with path interleaving. Our proposed control scheme adaptively adjusts the FEC block length and concurrently sends data interleaved over multiple paths. Experimental results with our approach show improved packet loss and signal to noise ratio performance.     

Understanding and identifying latent data races cross-thread interleaving

Data races are ubiquitous in multi-threaded applications, but they are by no means easy to detect. One of the most important reasons is the complexity of thread interleavings. A volume of research has been devoted to the interleaving-insensitive detection. However, all the previous work focuses on the uniform detection (unknown to the characteristics of thread interleavings), thereby making the detection defective in either reporting false positives or suffering from prohibitive overhead. To cope with the problem above, we propose an efficient, precise, and sound step-by-step resolution based on the characteristics of thread interleavings. We first try to tease apart the categories of thread interleavings from the several typical sources arising from the lock synchronizations. We then conduct a brief study and find a new and complex pattern the previous work cannot detect. It is also revealed that the simple pattern with the majority of thread interleavings can be resolved by a simple processing to achieve a big profit for the previous reordering-based design. Our final experimental results demonstrate the effectiveness of our empiricism-based approach, and show that 51.0% of execution time and 52.3% of trace size arising from the stateof-the-art reordering technique can be saved through a quick filtering of the simple pattern with a negligible (4.45%) performance overhead introduced on-the-fly.     

基于错误传播模型的非均等视频流丢失保护

提出一种适用于丢包网络、面向图像组（GOP）层的非均等视频流丢失保护方案。利用GOP中不同帧之间的非均等显著性,将不同数量前向错误校正包分配到GOP层的不同帧中。采用帧间包交错机制将突发包丢失分散到不同帧上,提高处理突发包丢失时的鲁棒性。仿真结果表明,在不同信道丢失模式下,该方案能提高视频接收质量。     

谱段交织预测的多光谱图像可逆信息隐藏算法

针对现有可逆信息隐藏算法嵌入容量不高并且不适合多光谱图像的问题,提出一种基于谱段交织预测的多光谱图像可逆信息隐藏算法.利用含秘图像像素值与原始图像像素值相差不大于1的特点,结合含秘谱段对多光谱图像进行多波段预测,通过预测误差直方图移位技术嵌入秘密信息.Landsat卫星和Terra卫星多光谱图像仿真结果表明,提出的算法和典型可逆信息隐藏算法相比具有更好的视觉质量和隐藏容量.     

SCADA系统冗余模式下数据同步的实现模型

SCADA系统作为一体化的工业自动控制系统，不仅要完成实时采集数据和远程控制等基本功能，而且其自身的稳定性和健壮性需要给予特别考虑。本文在介绍了SCADA系统软件基本结构后。重点讨论了冗余模式下实时数据和历史数据的同步问题。并给出了一种实现模型。     

组播错误控制技术

1.引言传统的点点通信(unicast)和广播通信(broadcast)是两种主要的通信方式,但随着Internet的日益普及、带宽的不断提高,利用IP组播技术在Internet上建立了虚拟的multicast backbone(Mbone),其上的点到多点通信的应用和各种工具也相继产生。人们可方便地在Mbone上举行远程视频会议,股票实时行情的分发,参与远程教育等。但可靠的组播协议的研究相对传统的点点协议而言,在错误控制、路由、流量控制、可伸缩性都具有其独有的特点,其复杂度也大得多。就错误控制和流量控制而言,传统的点点通信只涉及收发双     

Motion coordination for industrial robotic systems with redundant degrees of freedom

This work investigates how to distribute in an optimum fashion the desired movement of the end-effector of an industrial robot with respect to the workpiece, when there are redundant degrees of freedom, such as a positioning table. The desired motion is given as a series of acceleration functions in respective time intervals. The constraints of the optimisation are the available acceleration limit of axes, such as the table axes, the upper bounds to velocity and displacement of each axis and the avoidance of singular point areas of the robot, as defined by its manufacturer. The optimisation criterion is minimum total work for the motion. A genetic algorithm was used to solve the problem. The fitness function of the genetic algorithm calls a kinematics and dynamics simulation model of the robotic installation constructed in Matlab™, in order to compute the work consumed and to check possible violation of constraints. Examples of straight line and circular movement are given to prove the concept. Results are encouraging, yet demand on computing power is high.     

Questionnaire- versus voice-based screening for laryngeal disorders

The usefulness of questionnaire and voice data to screen for laryngeal disorders is explored. Answers to 14 questions form a questionnaire data vector. Twenty-three variables computed by the commercial “Dr.Speech” software from a digital voice recording of a sustained phonation of the vowel sound/a/constitute a voice data vector. Categorization of the data into a healthy class and two classes of disorders, namely diffuse and nodular mass lesions of vocal folds is the task pursued in this work. Visualization of data and automated decisions is also an important aspect of this work. To make the categorization, a support vector machine (SVM) is designed based on genetic search. Linear as well as nonlinear canonical correlation analysis (CCA) is employed, to study relations between the questionnaire and voice data sets. The curvilinear component analysis, performing nonlinear mapping into a two-dimensional space, is used for visualizing data and decisions. Data from 240 patients were used in the experimental studies. It was found that the questionnaire data provide more information for the categorization than the voice data. There are 3-4 common directions along which the statistically significant variations of the questionnaire and voice data occur. However, the linear relations between the variations occurring in the two data sets are not strong. On the other hand, very strong linear relations were observed between the nonlinear variates obtained from the questionnaire data and linear ones computed from the voice data. Questionnaire data carry great potential for preventive health care in laryngology.