SPI总线的UART扩展方法

借助于微处理器的SPI总线接口,利用NXP公司的一款芯片SC16IS752,提出一种基于SPI转UART的软硬件设计方案;着重介绍SPI-UART转换原理,并结合实际的应用系统,讨论了整个设计的可行性和实用性.实际应用表明,该方案经济、实用.     

Interaction of ISPs: Distributed Resource Allocation and Revenue Maximization

The Internet is a hierarchical architecture comprising heterogeneous entities of privately owned infrastructures, where higher level Internet service providers (ISPs) supply connectivity to the local ISPs and charge the local ISPs for the transit services. One of the challenging problems facing service providers today is how the profitability can be increased while maintaining good service qualities as the network scales up. In this work, we seek to understand the fundamental issues on the "interplay" (or interaction) between ISPs at different tiers. Although the local ISPs (which we term peers) can communicate with each other by purchasing the connectivity from transit ISPs, there stands an opportunity for them to set up private peering relationships. Under this competitive framework, we explore the issues on 1) the impact of peering relationship; 2) resource distribution; 3) revenue maximization; and 4) condition for network upgrade. First, a generalized model is presented to characterize the behaviors of peers and the transit ISP, in which their economic interests are reflected. We study how a peer can distributively determine its optimal peering strategy. Furthermore, we show how a transit ISP is able to utilize the available information to infer its optimal pricing strategy, under which a revenue maximization is achieved. Two distributed algorithms are proposed to help ISPs to provide a fair and efficient bandwidth allocation to peers, avoiding a resource monopolization of the market. Last, we investigate the above issues in a "many-peers region," that is, when we scale up the network. We provide insightful evidence to show that the ISPs can still gain profits as they upgrade the network infrastructures. Extensive simulations are carried out to support our theoretical claims.     

DocXS distributed operator construction and execution system

In the field of computer vision and pattern recognition, data processing and data analysis tasks are often implemented as a consecutive or parallel application of more-or-less complex operations. In the following we will present DocXS, a computing environment for the design and the distributed and parallel execution of such tasks. Algorithms can be programmed using an Eclipse-based user interface, and the resulting Matlab and Java operators can be visually connected to graphs representing complex data processing workflows. DocXS is platform independent due to its implementation in Java, is freely available for noncommercial research, and can be installed on standard office computers. One advantage of DocXS is that it automatically takes care about the task execution and does not require its users to care about code distribution or parallelization. Experiments with DocXS show that it scales very well with only a small overhead. The text was submitted by the authors in English. Steffen Wachenfeld received B.Sc. and M.Sc. (honors) degrees in Information Systems in 2003 and 2005 from the University of Muenster, Germany, and an M.Sc. (honors) degree in Computer Science in 2003 from the University of Muenster. He is currently a research fellow and PhD student in the Computer Science at the Dept. of Computer Science, University of Muenster. His research interests include low resolution text recognition, computer vision on mobile devices, and systems/system architectures for computer vision and image analysis. He is author or coauthor of more than ten scientific papers and a member of IAPR. Tobias Lohe, M.Sc. degree in Computer Science in 2007 from the University of Muenster, Germany, is currently a research associate and PhD student in Computer Science at the Institute for Robotics and Cognitive Systems, University of Luebeck, Germany. His research interests include medical imaging, signal processing, and robotics for minimally invasive surgery. Michael Fieseler is currently a student of Computer Science at the University of Muenster, Germany. He has participated in research in the field of computer vision and medical imaging. Currently he is working on his Master thesis on depth-based image rendering (DBIR). Xiaoyi Jiang studied Computer Science at Peking University, China, and received his PhD and Venia Docendi (Habilitation) degree in Computer Science from the University of Bern, Switzerland. In 2002 he became an associate professor at the Technical University of Berlin, Germany. Since October 2002 he has been a full professor at the University of Münster, Germany. He has coauthored and coedited two books published by Springer and has served as the co-guest-editor of two special issues in international journals. Currently, he is the Coeditor-in-Chief of the International Journal of Pattern Recognition and Artificial Intelligence. In addition he also serves on the editorial advisory board of the International Journal of Neural Systems and the editorial board of IEEE Transactions on Systems, Man, and Cybernetics—Part B, the International Journal of Image and Graphics, Electronic Letters on Computer Vision and Image Analysis, and Pattern Recognition. His research interests include medical image analysis, vision-based man-machine interface, 3D image analysis, structural pattern recognition, and mobile multimedia. He is a member of IEEE and a Fellow of IAPR.     

HBA: Distributed Metadata Management for Large Cluster-Based Storage Systems

An efficient and distributed scheme for file mapping or file lookup is critical in decentralizing metadata management within a group of metadata servers. This paper presents a novel technique called Hierarchical Bloom Filter Arrays (HBA) to map filenames to the metadata servers holding their metadata. Two levels of probabilistic arrays, namely, the Bloom filter arrays with different levels of accuracies, are used on each metadata server. One array, with lower accuracy and representing the distribution of the entire metadata, trades accuracy for significantly reduced memory overhead, whereas the other array, with higher accuracy, caches partial distribution information and exploits the temporal locality of file access patterns. Both arrays are replicated to all metadata servers to support fast local lookups. We evaluate HBA through extensive trace-driven simulations and implementation in Linux. Simulation results show our HBA design to be highly effective and efficient in improving the performance and scalability of file systems in clusters with 1,000 to 10,000 nodes (or superclusters) and with the amount of data in the petabyte scale or higher. Our implementation indicates that HBA can reduce the metadata operation time of a single-metadata-server architecture by a factor of up to 43.9 when the system is configured with 16 metadata servers.     

Rapid graph layout using space filling curves

Network data frequently arises in a wide variety of fields, and node-link diagrams are a very natural and intuitive represen- tation of such data. In order for a node-link diagram to be effective, the nodes must be arranged well on the screen. While many graph layout algorithms exist for this purpose, they often have limitations such as high computational complexity or node colocation. This paper proposes a new approach to graph layout through the use of space filling curves which is very fast and guarantees that there will be no nodes that are colocated. The resulting layout is also aesthetic and satisfies several criteria for graph layout effectiveness.     

A Constrained Line Search Optimization Method for Discriminative Training of HMMs

In this paper, we propose a novel optimization algorithm called constrained line search (CLS) for discriminative training (DT) of Gaussian mixture continuous density hidden Markov model (CDHMM) in speech recognition. The CLS method is formulated under a general framework for optimizing any discriminative objective functions including maximum mutual information (MMI), minimum classification error (MCE), minimum phone error (MPE)/minimum word error (MWE), etc. In this method, discriminative training of HMM is first cast as a constrained optimization problem, where Kullback-Leibler divergence (KLD) between models is explicitly imposed as a constraint during optimization. Based upon the idea of line search, we show that a simple formula of HMM parameters can be found by constraining the KLD between HMM of two successive iterations in an quadratic form. The proposed CLS method can be applied to optimize all model parameters in Gaussian mixture CDHMMs, including means, covariances, and mixture weights. We have investigated the proposed CLS approach on several benchmark speech recognition databases, including TIDIGITS, Resource Management (RM), and Switchboard. Experimental results show that the new CLS optimization method consistently outperforms the conventional EBW method in both recognition performance and convergence behavior.     

A model reference robust control with application to a flight control system design

In this paper, a new model reference robust control scheme for plants with relative degree greater than one is proposed for the purpose of coping with the “explosion of complexity” problem in control law design. The key of the scheme is that we use a first‐order filter to link each subsystem, so that the derivative of some nonlinear functions can be avoided. As a result, the final control law can be greatly simplified. The application of this scheme to a flight control system shows that both the tracking performance and the control effort can be improved significantly in comparison with earlier research. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society     

图像匹配技术在套印误差自动检测中的应用

准确检测套印偏差是印刷机自动套印系统中最为关键的技术;针对印刷色标图案的特点,提出了一种新的基于图像匹配的套印误差检测方法,通过相关匹配处理获取各单色色标的位置,并巧妙利用色标圆线的直径确定了系统的标称分辨率,进而计算出各色组问纵向和横向的套印误差;文中详细给出了算法原理和实验结果;相对于经典的边缘检测方法,图像匹配技术充分利用了色标图案的整体信息;实验结果表明,该方法对像素灰度的变化和系统噪声具有鲁棒性,检测精度高。     

基于信息融合的管道泄漏检测与定位技术应用研究

基于目前已经在石油输送管道中应用的SCADA系统将信息融合技术应用于管道泄漏检测与定位系统中;该方法应用管道泄漏时的多种特征信号,采用最优加权融合算法将多元信息综合处理,扩展了时间和空间上的检测范围,提高了泄漏检测系统的灵敏度和可靠性;在实验室用水泵和不锈钢管道组成的水循环系统进行了模拟实验,通过对比验证了信息融合检漏方法比单一检漏方法具有明显的优越性。     

基于VXI、PXI和LXI的网络化混合测试系统设计

文章介绍了混合测试系统整体结构,重点阐述了系统采用的硬件结构以及两种关键技术。此混合测试系统采用VXI总线、PXI总线和LXI总线共同组建,把三种单一总线系统的优点集于一体,既保护了测试资产中的已有投资而节省资金,又由于能继续使用熟悉的硬件、接口和软件,从而节省了时间。最后通过在项目中的应用得出了系统能缩短延时,并有效工作的结论。