基于骑士巡游的匀速移动图像置乱算法

好的图像置乱方法对提高图像置乱效果、降低密钥管理成本和提高抵抗攻击能力具有重要意义。本文提出基于骑士巡游的匀速移动算法置乱图像。首先把图像划分为区域A和区域B,然后把区域A和区域B的像素互换,使区域A的像素均匀分布到区域B中,最后使用骑士巡游算法从局部和全局2个方面进行置乱图像。实验表明本文方法能有效减少加密密钥数量,具有较好的置乱效果和较好的抗干扰性。     

基于感兴趣区域的率失真优化帧内刷新算法研究

由于视频图像中不同区域的重要性存在着很大差异,人眼对其主观质量的要求也不一样,因此对感兴趣区域的前景图像和非感兴趣区域的背景图像的主观质量要求也可以不一样,尽管目前对感兴趣区域的研究已有不少,但是将全局率失真优化、码率控制、帧内宏块刷新和感兴趣区域结合的相关研究并不多见。基于此提出了基于人眼感兴趣区域的率失真优化帧内宏块刷新算法,该算法采用端到端的全局率失真理论,对感兴趣区域和非感兴趣区域进行分析处理,使感兴趣区域的宏块能得到更及时的帧内刷新,由于受到码率的限制,必须对感兴趣区域和非感兴趣区域重新进行码率分配。最后,在JVT的JM12.2平台上实现该算法。大量实验结果表明,与传统的基于率失真优化的帧内刷新算法相比,基于感兴趣区域的率失真优化帧内刷新算法在感兴趣区域能够取得更好的主观质量。     

感兴趣区域分割的非平衡多描述视频编码

视频序列中感兴趣区域信息的丢失将导致视频质量的严重下降,通过一定的算法检测出感兴趣区域,并通过修改H.264编码标准中的数据分割算法,把这部分信息的Inter宏块放入B类数据分割中,然后对新形成的三类数据运用非平衡多描述编码方法进行编码,实验结果表明,该方法在网络出错时可以有效地保证视频中感兴趣区域的数据,很好地改善接收到的视频质量。     

一种新的数字图象置乱隐藏算法

基于骑士巡游问题（Knight-tour problem),提出了一种新的图象置乱算法,该算法主要有两步：求骑士巡游矩阵和按巡游矩阵作图象置乱变换。对于求骑士巡游矩阵提出了“智能试探－智能试探－智能回溯算法”,克服了传统的“试探－回溯算法”的不足,提高了求骑士巡游矩阵的效率所提出的图象置乱隐藏算法,优于已有算法的地方是密钥量大和加密解密速度快;从而增加了图象及其隐藏信息的安全性和应用性。     

基于宏块编码信息自适应置换的H.264/AVC视频加密方法

云存储的发展使人们愿意将个人视频数据传输至云端,但伴随而来的数据安全问题日益突出,选择加密是对视频进行隐私保护的有效手段之一。针对目前H.264/AVC视频选择加密方法普遍存在安全性不足的问题,文中提出了一种基于宏块编码信息自适应置换的H.264/AVC视频加密方法。该方法根据宏块的编码类型逐帧自适应生成伪随机序列,利用伪随机序列将宏块编码信息中的残差编码方案(Coded Block Pattern, CBP)和残差数据(Residual)在宏块间进行随机置换,同时还对Ⅰ宏块的帧内预测模式以及P宏块与B宏块的运动向量差值的符号进行加密。实验结果表明,该方法可保证加密视频兼容H.264/AVC编码标准,并具有加密空间大、密钥敏感性好、视频码率变化小的特点。与现有的主流加密方案相比,所提方法在视觉安全性和抵抗最新提出的轮廓攻击方面表现更佳。     

基于感兴趣区域的H.264视频加密算法

为了解决现有的基于H.264的加密算法无法满足安全性和加密效率之间较好折衷的问题,提出两种基于感兴趣区域的H.264加密算法,将感兴趣区域的提取和基于熵编码的H.264加密算法相结合,只对提取出来的感兴趣区域进行加密.设计了一种基于人脸检测的加密算法,并通过修改模式选择算法,去掉了使得非人脸区域参考人脸区域的帧间宏块预测类型,解决了由帧间预测引起的人脸加密区域变形的问题.将运动对象的检测与提取和H.264的编码过程结合,设计了一种基于运动对象检测的H.264加密算法.实验结果表明,这两种加密算法能够在不降低算法安全性的情况下获得安全性和加密效率之间的较好折衷,可以满足实时应用的需求.     

一种基于宏块数据划分的H.264视频加密方案

H.264是最新的视频编码标准,被广泛地用于各种视频应用中。由于视频数据传输的广泛性和便易性,使得视频数据安全成了一个亟待解决的问题。提出一种在H.264编码下基于宏块重要性分类的加密方案,根据宏块重要程度的不同,运用不均等加密策略对重要宏块优先进行加密操作,减少加密的数据量。在具体的加密过程中,联合加密几种宏块语义层中的定长语法元素,在保持视频语义的情况下,提高了加密的安全性。理论和实验分析证明,该加密方案满足实时性和安全性的要求,有效地保护了视频安全。     

一种新型的基于离散化宏块及螺旋扫描的视频数据打包算法

在研究传统视频数据打包算法中所采用的光栅扫描方式的局限性基础上，融合离散化宏块和螺旋扫描，融合这两种算法提出了一种新的视频数据打包算法，该算法首先按照某种规则离散化编码宏块，然后再从人眼感兴趣的中心区域开始，螺旋形步进打包．理论和试验都证明了这种新型的打包算法一方面可以有效地提高数据包抗丢包、抗误码的性能，另一方面可以使得数据包具有一定的可伸缩性，该算法比传统的打包算法在解码输出质量上具有明显的提高。     

马步哈密顿圈(骑士巡游)在图像置乱加密方法上的应用

基于骑士巡游变换的置乱算法是目前图像加密方法研究的热点,它的密钥量大,安全性高,但传统日字形马步(1,2)的置乱只能隐藏图像的细节.为了克服此缺点,提出基于骑士巡游变换的改进置乱算法.包括(1)基于骑士巡游类生矩阵的图像置乱方法;(2)分块分层的置乱算法;(3)将骑士巡游变换和Arnold变换结合的一种复合置乱算法.这些改进置乱算法,扩大了密钥库,增强了置乱的效果.文中给出这几种改进算法的实际应用效果.     

基于H.264的车牌快速保护方案

在一些保密要求严格的场合,监控视频泄露个人隐私,已引起了人们的广泛关注。针对视频中车牌区域加密的问题提出一种基于H.264的车牌快速保护方案。首先使用HSV颜色模型搜索出车牌区域,并通过H.264中的灵活宏块排序FMO(Flexible Macroblock Orde)技术将一帧中车牌区域和背景区域的宏块映射到不同的组。然后提出一个一维混合混沌序列,用来生成二值密钥流。最后在参考适应性二元算术编码CABAC(Context-based Adaptive Binary Arithmetic Coding)编码过程中使用该密钥流对车牌区域进行加密。实验结果表明,该方案不仅具有良好的鲁棒性,而且快速有效地保护了车牌区域。     

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)

正~~     

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