一种增强MPEG-4数据分割鲁棒性的新算法

首先对MPEG-4码流各语法组元的重要性进行了分析，并将最重要的纹理信息进一步细分测试，得出不同的高频纹理信息具有不同重要性的结论。在此基础上，针对MPEG-4标准数据分割方法将编码的高频纹理信息等同对待、以至当高频细节的视频帧出错时掩盖效果不佳的缺点，提出了一种新的数据分割算法(NewDP)。该算法内嵌了MPEG-4标准数据分割算法的结构，并充分考虑了重要的高频纹理信息，在简单的错误掩盖处理后，获得比标准数据分割方法高出2～3dB的平均峰值信噪比(Peak signal-noise ratio，PSNR)增益，可考虑运用于无线信道等易出错环境下的鲁棒视频传输场合。     

改进的块复制不等差错保护喷泉码

在多媒体传输、深空通信等应用中,由于数据的重要性程度不同,需要喷泉码具有不等差错保护的特性,根据数据重要性给予不同程度的保护。对基于块复制的不等差错保护喷泉码的机制进行了理论分析,提出了改进的信息符号选取策略,让度1编码符号全部在重要信息比特中选取,一定数量的度2编码符号分别在重要信息比特和次要信息比特中选取,从局部上提升对重要信息比特的保护。仿真结果表明,相比于现有的基于块复制的不等差错保护喷泉码,改进方法在进一步提高重要信息比特保护的同时没有降低对次要信息比特的保护,且有更好的不等恢复时间性能。     

基于Token追踪的分布式互斥算法

本文首先提出一切合实际的互斥信件量度量方法,该方法不仅考虑请求结点所发的信息数,同时还考虑信件的存储转发次数,然后针对任一拓扑结构,在充分利用局部信息与已知信息的基础上,给出了互斥信件量为0～2(n—1)(n为结点数)的有效互斥算法,该算法不仅在互斥信件量上是目前最优的,而且充分体现了分布式算法设计的一个重要原则,充分利用一切已知信息作为未来决策的依据。     

关于一般图形Voronoi图的离散构造法的研究

生成元为任意图形的一般图形Vomnoi图，由于其生成元的任意性，使得构造一般图形Voronoi图的算法均比较复杂。本文给出了在生成元边界上选取母点，利用点为生成元的Voronoi图的离散画法进行构造，从而得到一般图形Voronoi图的离散构造法。与其它算法相比，该算法的实现与生成元的形状无关，无需复杂计算，无需考虑误差控制，因而更加实用，效率也更高。实验结果表明，该算法简单，具有较高的理论价值和应用价值。     

基于Voronoi图的自动白平衡算法

在数码相机系统中,不同色温下的图像存在偏色现象,而传统白平衡算法不能准确重现图像的真实颜色。为此,提出一种基于 Voronoi图的自动白平衡算法。利用Voronoi图统计白点数,估计当前环境的色温值,并做增益计算,根据标准值对图像颜色值进行校正。在不同背景和光源下的测试结果表明,该算法可使图像质量得到有效改善。     

基于条件随机场和低采样率浮动车数据的地图匹配算法

提出了一种基于条件随机场和低采样率浮动车数据的地图匹配算法。首先建立道路网络模型,在此基础上,计算GPS观测点可能匹配的候选投影点集合以及集合中每一个候选投影点的观测概率,再计算相邻GPS观测点的候选路径集合以及每两个相邻候选投影点之间的传递概率;然后根据这些候选投影点和候选路径,在滑动窗口内,基于条件随机场模型应用前后向递归算法,计算每个候选投影点的概率权重值;最后根据概率权重值,选取GPS观测点的最佳匹配投影点。该算法(FB-MM)在低采样率的情况下,综合考虑了道路网络的拓扑结构和GPS观测点之间的关联信息,实现了较好的地图匹配效果。     

融合深度信息的BRISK改进算法

为了有效地利用RGB-D图像的深度信息,提高BRISK算法的尺度不变性和旋转不变性,提出一种融合深度信息的BRISK改进算法。首先,采用FAST算法提取特征点,并计算每个特征点的Harris角点响应值;然后,将整个图像划分为大小相同的网格,每个网格保留Harris角点响应值最大的特征点;其次,根据图像的深度信息直接计算特征点的尺度因子;最后,计算以特征点为中心的圆的灰度矩心,通过灰度矩心和特征点的位置偏差确定特征点主方向。从尺度不变性和旋转不变性两方面对几种算法进行了对比实验分析。实验结果表明,相比BRISK算法,改进后的算法在图像尺度变化时正确匹配特征点数提高了90%以上,在图像旋转时正确匹配特征点数提高了至少70%。     

高效的MPR选择算法

OLSR(optimized link state routing)协议中最重要的功能之一是多点中继(multi point relays, MPR)节点的选择,该协议中路由的计算就要依靠MPR选择相关表项。传统的MPR算法只是减少了同一区域内相同消息的泛洪,并没有考虑网络中新加入节点获取全网拓扑信息的时间问题。针对该问题进行了研究并提出一种高效的MPR选择算法,该算法有三个步骤:首先减少了部分拓扑控制(topology control, TC)消息冗余问题;然后选择MPR时考虑有效覆盖面积让新加入的节点获取全网拓扑信息所需的时间缩短;最后考虑到移动性对网络拓扑的影响,基于历史信息预估下一时刻节点的位置,增强了链路的稳定性。通过仿真,将改进的MPR算法与传统算法比较,端到端时延降低,数据包的传递成功率也有所提升。     

基于Voronoi图的无线传感器网络K覆盖算法

针对无线传感器网络(WSN)在随机高密度部署节点情况下的多重覆盖问题,提出一个基于Voronoi图的K覆盖算法。该算法利用邻居节点信息计算Voronoi覆盖邻居节点集,构建有向Voronoi覆盖关系图,通过调整关系图中的节点状态实现K覆盖。仿真结果表明,该算法能正确判断网络覆盖率,连通K覆盖的近似最小活动节点集数目少于CCP算法。     

基于Voronoi图的二维地层剖面重构

本文着手地质结构几何重构问题的研究，将由地质勘测得到的稀疏异质数据点的几何拓扑信息作为初始数据，重新构造二维地层截面图。重构分三步完成：首先构造输入数据点集的Voronoi图模型，然后合并相邻同质Voronoi多边形，最后对每个地层边界作光顺处理。该算法已成功地运行了许多实例，实验结果显示这种方法非常有效，而且推广到
到三维地质结构重构。     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

View-based model-driven architecture for enhancing maintainability of data access services

In modern service-oriented architectures, database access is done by a special type of services, the so-called data access services (DAS). Though, particularly in data-intensive applications, using and developing DAS are very common today, the link between the DAS and their implementation, e.g. a layer of data access objects (DAOs) encapsulating the database queries, still is not sufficiently elaborated, yet. As a result, as the number of DAS grows, finding the desired DAS for reuse and/or associated documentation can become an impossible task. In this paper we focus on bridging this gap between the DAS and their implementation by presenting a view-based, model-driven data access architecture (VMDA) managing models of the DAS, DAOs and database queries in a queryable manner. Our models support tailored views of different stakeholders and are scalable with all types of DAS implementations. In this paper we show that our view-based and model driven architecture approach can enhance software development productivity and maintainability by improving DAS documentation. Moreover, our VMDA opens a wide range of applications such as evaluating DAS usage for DAS performance optimization. Furthermore, we provide tool support and illustrate the applicability of our VMDA in a large-scale case study. Finally, we quantitatively prove that our approach performs with acceptable response times.     

A pragmatic multi-method investigation of discrepant technological events: Coping,attributions, and ‘accidental’ learning

Discrepant technological events or situations that entail a problem, a misunderstanding or a difficulty with the Information Technology (IT) being employed, are common in the workplace, and can lead to frustration and avoidance behaviors. Little is known, however, about how individuals cope with these events. This paper examines these events by using a multi-method pragmatic approach informed by coping theory. The results of two studies – a critical incident study and an experiment – serve to build and test, respectively, a theoretical model that posits that individuals use a variety of strategies when dealing with these events: they experience negative emotions, make external attributions, and adopt engagement coping strategies directed at solving the event, eventually switching to a disengagement coping strategy when they feel they have no control over the situation. Furthermore, users’ efforts may result in ‘accidental’ learning as they try to overcome the discrepant IT events through engagement coping. The paper ends with a discussion of the results in light of existing literature, future opportunities for research, and implications for practice.     

The Distributed Time-Triggered Simulation Scheme: Core Principles and Supporting Execution Engine

Distributed real-time simulation is a young technology field but its practice is under increasing demands. In recent years the author and his collaborators have been establishing a new approach called the distributed time-triggered simulation (DTS) scheme which is conceptually simple and easy to use but widely applicable. The concept was initiated in the course of developing a new-generation object-oriented real-time programming scheme called the time-triggered message-triggered object (TMO) programming scheme. Some fundamental issues inherent in distributed real-time simulation that were learned during recent experimental studies are discussed along with some approaches for resolving the issues. An execution engine developed to support both the TMOs engaged in control computation and the TMOs engaged in DTS is also discussed along with its possible extensions that will enable significantly larger-scale DTSs.     

Software-Konfigurationsmanagement in großen Softwareprojekten

Zusammenfassung Mit zunehmender Größe der Softwaresysteme verschärfen sich die für die Software-Herstellung typischen Probleme: Beherrschen großer Objektmengen, Erhalten der Systemkonsistenz, Kontrolle der ständigen Änderungseinflüsse und Gewährleisten einer langen Lebensdauer. Die Disziplin Konfigurationsmanagement bildet den methodischen Ansatz, diese Probleme besser zu beherrschen. Software-Konfigurationsmanagement faßt die Herstellung von Softwaresystemen als eine Abfolge von kontrollierten Änderungen an gesicherten Zwischen- und Endergebnissen auf. Dargestellt werden die Objekte und Funktionen des Software-Konfigurationsmanagements sowie die hierfür in großen Software-Projekten benötigten Methoden, Instanzen und Hilfsmittel.     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and     

Editorial:Brain-machine interface(BMI) and cyborg intelligence

正Brain-machine interfaces(BMIs)aim at building a direct communication pathway between the brain and an external device,and represent an area of research where significant progress has been made during the past decade.Based on BMIs,mind information can be read out by neural signals to control     

Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate     

SCIENCE CHINA Information Sciences SUBJECT INDEX TO VOLUME 57(2014)

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Information for Authors

正http://www.zju.edu.cn/jzus http://www.springerlink.com Aim The Journals of Zhejiang University-SCIENCE(A/B/C)are edited by the international board of distinguished Chinese and foreign scientists,and are aimed to present the latest developments and achievements in scientific research in China and overseas to the world’s scientific circles,especially to stimulate