Efficient self-certified proxy CAE scheme and its variants

Elaborating on the merits of proxy signature schemes and convertible authenticated encryption (CAE) schemes, we adopt self-certified public key systems to construct efficient proxy CAE schemes enabling an authorized proxy signer to generate an authenticated ciphertext on behalf of the original signer. To satisfy the requirement of confidentiality, only the designated recipient is capable of decrypting the ciphertext and verifying the proxy signature. A significant advantage of the proposed schemes is that the proxy signature conversion process takes no extra cost, i.e., when the case of a later dispute over repudiation occurs, the designated recipient can easily reveal the ordinary proxy signature for the public arbitration. If needed, the designated recipient can also convince anyone that he is the real recipient. In addition, integrating with self-certified public key systems, our schemes can earn more computational efficiency, since authenticating the public key and verifying the proxy signature can be simultaneously carried out within one-step.     

Special issue on omnidirectional vision and its applications

Machine Vision and Applications -     

CAE技术的全球化

崛起于航空航天的CAE(Computer Aided Engineering)技术今天已经成为很多行业进行科学研究、技术创新以及产品设计的重要技术手段.几十年前欧美借助全球领先的航空航天中的计算分析技术以及成熟的商业运营模式,成功地将计算机分析与仿真技术制成便于操作的商业软件包,使其应用范围和求解问题的能力空前增长.近10年来,CAE技术已经通过软件运营商和商业流通渠道,成为发达国家结构分析、产品造型、新材料开发、医药化工、人机工程等各领域普遍采用的数字化虚拟仿真平台.     

Quadtree-based genetic algorithm and its applications to computer vision

Many computer vision problems can be formulated as optimization problems. Presented in this paper is a new framework based on the quadtree-based genetic algorithm that can be applied to solve many of these problems. The proposed algorithm incorporates the quadtree structure into the conventional genetic algorithm. The solutions of image-related problems are encoded through encoding the corresponding quadtrees, and therefore, the 2D locality within a solution can be preserved. Examples addressed using the proposed framework include image segmentation, stereo vision, and motion estimation. In all cases, encouraging results are obtained.     

实时卫星导航接收机在独立DSP平台上的设计实现

针对目前卫星导航接收机通常需要依赖FPGA芯片或ASIC芯片,功能扩展升级困难的问题,提出了基于独立DSP芯片的模块化卫星导航接收机平台的构建方法,并研究了中频卫星信号的实时采集、程序和数据的分配与存储、线程调度管理技术.在此基础上,以TI公司的TMS320C6416芯片为实例,设计实现了实时软件接收机样机.实验结果表明,依照该方案设计的平台能够很好地实现实时卫星导航软件接收机的功能.     

CAE技术回顾与展望

计算机技术的进步和企业的需求促进了CAE的迅速发展。文章对CAE进行了较全面的概述,首先介绍了产生背景与发展历程,然后分析了CAE的发展与应用现状,最后阐述了其未来发展趋势。     

Pervasive and standalone computing: the perceptual effects of variable multimedia quality

The introduction of multimedia on pervasive and mobile communication devices raises a number of perceptual quality issues; however, limited work has been done examining the three-way interaction between use of equipment, quality of perception and quality of service. Our work measures levels of informational transfer (objective) and user satisfaction (subjective) when users are presented with multimedia video clips at three different frame rates, using four different display devices, simulating variation in participant mobility. Our results will show that variation in frame rate does not impact a user's level of information assimilation, however, does impact a users’ perception of multimedia video ‘quality’. Additionally, increased visual immersion can be used to increase transfer of video information, but can negatively affect the users’ perception of ‘quality’. Finally, we illustrate the significant affect of clip-content on the transfer of video, audio and textual information, placing into doubt the use of purely objective quality definitions when considering multimedia presentations.     

基于独立DSP平台的实时卫星导航接收机的设计

以TI公司的TMS320C6416芯片为例,设计实现了基于独立DSP芯片的通用卫星导航接收机平台,说明了如何通过单独的DSP平台实现中频卫星信号的采集、程序和数据的存储、线程调度等功能,以及如何支持多星座卫星导航接收机扩展。实验结果表明,根据本方案实现的平台能够很好地实现实时卫星导航软件接收机的功能。     

Evolutionary aspects of CAE systems

Computer-aided engineering (CAE) comprises several disciplines of computer application to engineering problems. From a systems analysis point of view, the different stages of the development of a new product may be mapped on to disciplines such as computer-aided design, computer-aided manufacturing, and others. These constituents of CAE are briefly discussed, with emphasis on the need for their integration. A short review of the development of CAE systems technology is also given. Present trends and needs for more research are indicated.     

游戏梦工场

“大话西游”里面有句经典的台词：“我猜中了开头，可是我猜不着这结局。”夕阳武士这番话可以带给观众无限的遐想，观众记住了这部电影。制作游戏和制作电影一样，一定要抓住玩家的心态，了解玩家的期望，适当留下悬念，这样才能吸引玩家。那玩家期望的到底是什么呢？     

游戏梦工场

二，玩家的需要 大学时的一个舍友QQ签名有点意思：“如果一个游戏设计师根本不知道玩家为什么要玩游戏，那他是在作梦而不是造梦。”这期．我就和大家。聊聊玩家为什么要玩游戏。     

基于改进SIFT特征的双目图像匹配算法

针对SIFT（尺度不变特征变换）算法无法准确定位物体形状特征的问题,提出了一种结合了Harris角点和SIFT算法的立体匹配方法。在DOG尺度空间提取Harris算子作为图像的特征点并为每个特征点定义主方向,计算出特征点的32维特征向量描述子并用BBF算法检索同名特征点之间的欧式距离进行匹配。在降低SIFT算法的时间复杂度的同时提高了算法提取特征点的形状意义,在双目图像匹配实验中取得了较好的结果。     

基于单目视觉传感器的车距测量与误差分析

为了解决结构化道路上基于单目视觉的运动车辆车距测量问题,从针孔模型下摄像机成像的基本原理出发,推导出基于图像中车道线消失点的车距计算公式.车距测量结果只与图像中的近视场点到摄像机的实际距离有关,而无需对所有的摄像机参数进行标定.分析了车距测量中的误差因素,并在前方道路上设置已知距离的横向标线,完成了摄像机不同安装高度、俯仰角及方向角情况下的标线距离测量实验.通过与实际距离比较发现,摄像机安装高度与方向角的微小变化对车距测量的影响可以忽略,而摄像机俯仰角的变化将引起较大的车距测量误差.最后,完成了不同距离处前方车辆车距测量实验,实验结果表明:采用上述方法的车距测量相对误差小于3％,具备了较高的检测精度.     

游戏梦工场

上海某网络游戏运营商为了打击非法外挂．一夜封杀12万游戏玩家账号。其后，在该游戏运营商的组织下．百余名游戏玩家集体献血，其中半数被封账号的玩家因此而被“解封”。专家称以“解封”为条件鼓励玩家献血不妥。[编者按]     

CAD与CAE集成的研究

产品设计和工程分析有效集成是获得满足T、Q、C、S、G性能产品的重要保障。阐述了实现CAD产品设计与CAE工程分析有效集成的影响因素。对CAD、CAE的集成进行了分类,并提出了“以CAE为中心”新的设计方式和基于这种方式的新的集成思想。     

燃油分配管总成的结构CAE仿真及实验验证

采用有限元方法与模态试验技术,分析了燃油分配管总成的频率特性. 提出了几种简化结构的思路,并在实验中加以验证.     

断裂分析及CAE软件的现状与发展

断裂过程贯通宏观、细观和微观等多个层次尺度,涉及固体力学、材料科学和物理学等多个学科领域,是工程构件与装备最主要也最危险的失效破坏形式.美国众议院一份经济调查报告显示,断裂使美国一年损失1190亿美元,约占1982年美国国内生产总值的4％