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SpaceWire Satellite Onboard Data-Handling Networks

IFAC proceedings Volumes 2004年第6期37卷 759-764页

作者： Steve Parkes Chris McClements Iain Martin Stuart Mills Ray Manston Martin Dunstan Space Systems Research Group University of Dundee Applied Computing Dundee DD1 4HN Scotland UK

SpaceWire is a communications network being widely used onboard current spacecraft. It is designed to connect high data-rate sensors, large solid-state memories, processing units and the downlink telemetry subsystem providing an integrated onboard, data-handling network. SpaceWire links are serial, high-speed, bi-directional, full-duplex, point-to-point data links which connect together Space Wire equipment. Application information is sent along a SpaceWire link in discrete packets. Control and time information can also be sent along Space Wire links. This paper introduces the SpaceWire standard and describes the key features of SpaceWire. Development and test equipment designed to support users of SpaceWire is also described.

关键词： Networks Digital Communications Data-handling Satellite Space

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Content delivery networks and their roles in eLearning

Content delivery networks and their roles in eLearning

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IEEE Signal Processing and Communications Applications (SIU)

作者： M.A. Turker Siemens Business Services Sistem Hizmetleri Ankara Turkey

Content delivery networks (CDN) utilize the large caching capacities at the edges of the network to ease down the media serving requirements of Internet sites and to enable faster delivery of content to the end users. CDN technology can scale from small enterprise networks to large global networks. In the case of eLearning content, a heterogeneous network with a mixture of options can be used. CDN caches are updated frequently enough to mirror the right content of the site, yet the updates are at times which would not load the network during heavy demand. Edge side includes (ESI) enable personalization features and simultaneous use of distributed databases. Having established a wide-area load balancing, to establish the same at the local area, peer-to-peer file sharing techniques can be applied.

关键词： Intelligent networks Electronic learning Internet Peer to peer computing HTML IP networks Mirrors Distributed databases Spatial databases Load management

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B10: Implementation of configurable system on a chip with microblaze processor core

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IFAC proceedings Volumes 2004年第20期37卷 222-227页

作者： Miloš Bečvář Tomáš Brabec Department of Computer Science and Engineering Faculty of Electrical Engineering Czech Technical University in Prague Karlovo nám. 13 Prague 2 Czech Republic

Configurable System on A Chip consisting of general-purpose processor and configurable coprocessor is studied as a platform for algorithm acceleration. A simple model for quantitative evaluation ofi interface between processor and coprocessor is presented and applied to Xilinx Microblaze based system. Several architectural variants for coprocessor interface are described and evaluated. Efect ofi coprocessor on execution time is demonstrated by implementation ofi thee simple SW kernels – 32-bit CRC, RGB-to-YCrCb computation and IDCT. These kernels ilustrate that data transfer overhead has very high impact to execution time even when low latency SoC buses and links are used. Even with these overheads, significant speedup over SW implementation can be achieved.

关键词： Configurable computing Algorithm Accelerattion FPGA Processor Core Coprocessor

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Test framework for IPv6 conformance testing

Test framework for IPv6 conformance testing

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Asia-Pacific Conference on Communications

作者： Yujun Zhang Zhongcheng Li Institute of Computing Technology Chinese Academy and Sciences Beijing China

ISBN: (纸本)0780386019

It is necessary to perform IPv6 testing at present. The standard test framework isn't appropriate for IPv6 testing in test packet description and complicated algorithm implementation. Based on analyzing IPv6 features and test requirements, IPv6 test framework is proposed. Test packet description notation (TPDN) is defined. Complicated algorithms are implemented in test system by high-level programming language. Test suite can invoke algorithm modules by algorithm property. Test practice is performed to prove the validity of the framework. IPv6 test framework can also be applied to other protocol testing that has packets with structural features and complicated algorithms.

关键词： Protocols Internet Performance evaluation ISO standards IEC standards Costs Plugs Quality of service System testing Computer languages

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PER: a power-life extension routing protocol using a round robin scheme for mobile ad hoc networks

PER: a power-life extension routing protocol using a round r...

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proceedings of the IEEE Circuits and Systems symposium on Emerging Technologies

作者： Yuh-Shyan Chen Chao-Yu Chiang Department of Computer Science and Information Engineering National Chung Engineering University Chiayi Taiwan

A mobile ad hoc network (MANET) consists of mobile hosts which can peer-to-peer communicate with other mobile hosts through the multi-hopping routing. Each mobile device which operates the mobile computing and wireless communication operations is mainly depended on the battery. The power consumption of the battery is very important for supporting the wireless mobile applications. This problem is intensively investigated in wireless mobile ad hoc networks. In this paper, we propose a PER: power-life extension routing protocol using a round robin scheme for wireless mobile ad hoc networks. Existing power-awareness routing protocols in MANETs mainly search for a power-awareness route with the consideration of the minimum total transmission power (MTPR protocol), or the minimum battery cost (MBCR protocol), the min-max battery cost (MMBCR protocol), and the minimum drain rate (MDR protocol). The key idea of our scheme is a simple multi-path routing between each possible pair of two three-hop neighboring nodes. This scheme identifies many disjoint sub-paths between one pair of three-hop neighboring nodes. A round robin scheme is applied on the multiple disjoint sub-paths such that the power consumption can be evenly distributed into all subpaths, such that each sub-path is responsible for the less amount of power consumption. This scheme can promote and extend the power-awareness route lifetime. Finally, the simulation results demonstrate this improvement.

关键词： Routing protocols Round robin Mobile ad hoc networks Batteries Energy consumption Mobile computing Ad hoc networks Costs Chaotic communication Computer science

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Trends In Optimization: American Mathematical Society Short Course, January 5-6, 2004, Phoenix, Arizona

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丛书名： proceedings of Symposia in applied Mathematics 061

2004年

作者： Rekha R. Thomas Serkan Hosten Jon Lee

ISBN: (纸本)9780821835845

This volume presents proceedings from the AMS short course, Trends in Optimization 2004, held at the Joint Mathematics Meetings in Phoenix (AZ). It focuses on seven exciting areas of discrete optimization. In particular, Karen Aardal describes Lovasz's fundamental algorithm for producing a short vector in a lattice by basis reduction and H.W. Lenstra's use of this idea in the early 1980s in his polynomial-time algorithm for integer programming in fixed dimension. Aardal's article, "Lattice basis reduction in optimization: Selected Topics", is one of the most lucid presentations of the material. It also contains practical developments using computational tools. Bernd Sturmfels' article, "Algebraic recipes for integer programming", discusses how methods of commutative algebra and algebraic combinatorics can be used successfully to attack integer programming problems. Specifically, Gröbner bases play a central role in algorithmic theory and practice. Moreover, it is shown that techniques based on short rational functions are bringing new insights, such as in computing the integer programming gap. Overall, these articles, together with five other contributions, make this volume an impressive compilation on the state-of-the-art of optimization. It is suitable for graduate students and researchers interested in discrete optimization.

关键词： Literary Collections

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Consistent groupwise non-rigid registration for atlas construction

Consistent groupwise non-rigid registration for atlas constr...

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IEEE International symposium on Biomedical Imaging

作者： K.K. Bhatia J.V. Hajnal B.K. Puri A.D. Edwards D. Rueckert Visual Information Processing Department of Computing Imperial College London UK Robert Steiner Magnetic Resonance Unit Imaging Sciences Department Imperial College London UK Obstetrics and Gynaecology Faculty of Medicine Department of Paediatrics Imperial College London UK

This paper describes a groupwise, non-rigid registration algorithm to simultaneously register all subjects in a population to a common reference (or natural) coordinate system, which is defined to be the average of the population. This natural coordinate system is calculated implicitly by constraining the sum of all deformations from itself to each subject to be zero. To do this, the gradient projection method for constrained optimization is applied to maximize the similarity between the images, subject to the constraint being satisfied. The algorithm has been tested on a group of 19 brain MR images acquired from a population of subjects with schizophrenia.

关键词： Educational institutions Pediatrics Biomedical imaging Image registration Shape Information processing Magnetic resonance Magnetic resonance imaging Gynaecology Registers

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A direct method for exact discretization of ordinary differential equations

A direct method for exact discretization of ordinary differe...

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Midwest symposium on Circuits and Systems (MWSCAS)

作者： S. Kawarai Research Laboratory Anritsu Company Atsugi Japan

Differential equations are frequently used to analyze and design analog circuits and numerically solved from computation of difference equations. The equivalent difference equations are obtained by using the solutions or the Laplace transform of the corresponding differential equations for exact discretization. Here, we propose a direct method for exact discretization obtaining the equivalent difference equation whose solution is equal to the solution of a differential equation at any discrete periodic point. The direct method greatly differs from the existing method in needing neither the solutions nor the Laplace transform of differential equations. The equivalent difference equations are readily produced by direct transform of replacing (d/dt-/spl alpha/)x(t) with (1-e/sup /spl alpha/T/E/sup -1/)x/sub n/ in factorized differential equations (where x/sub n/ equal to by definition x(nT), /spl alpha/ is a constant, T the sampling period, and E the shift operator defined by E/sup -1/x/sub n/=x/sub n-1/). The method is applied to some examples including ordinary differential equations (ODEs) and nonlinear one of logistic equation which represents the chaos behavior. The proposed method is the simplest, easiest and fastest method ever, and very important and useful for generating exact numerical solutions of ODEs.

关键词： Differential equations Difference equations Laplace equations Analog circuits Analog computers Circuit analysis computing Discrete transforms Sampling methods Logistics Nonlinear equations

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A computational technique for interactive needle insertions in 3D nonlinear material

A computational technique for interactive needle insertions ...

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IEEE International Conference on Robotics and Automation (ICRA)

作者： H.-W. Nienhuys A.F. van der Stappen Institute of Information and Computing Sciences University of Utrecht Utrecht Netherlands

We present a computational method for simulating needle insertions interactively in both 2D and 3D models of soft tissue. The approach is based on the Finite Element Method (FEM) and uses quasi-static stick-slip friction for needle/tissue interactions. The FEM equations are solved using an iterative method, and the mesh is refined adaptively near the needle trajectory. The boundary formed by the needle surface is not represented explicitly in the mesh, but its geometry is accounted for in the friction forces. This has the advantage that we can use a simple and therefore fast refinement scheme that is guaranteed to keep the mesh quality at the initial level. This approach can also be applied to the 3D situation as well as to nonlinear geometry and material models. We present results of computational experiments of the 2D simulation, and show promising samples of the 3D implementation.

关键词： Needles Computational modeling Friction Geometry Biological materials Biological tissues Finite element methods Nonlinear equations Iterative methods Solid modeling

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Distributed pagerank: a distributed reputation model for open peer-to-peer network

Distributed pagerank: a distributed reputation model for ope...

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Workshops on Applications and the Internet (SAINT)

作者： A. Yamamoto D. Asahara T. Itao S. Tanaka T. Suda NTT Network Innovation Laboratories Musashino Japan Department of Applied Mathematics and Physics Graduate School of Informatics Kyoto University Kyoto Japan University of California CA USA

This paper proposes a distributed reputation model for open peer-to-peer networks called distributed pagerank. This model is motivated by the observation that although pagerank has already satisfied the requirements of reputation models, the centralized calculation of pagerank is incompatible with peer-to-peer networks. Distributed pagerank is a decentralized approach for calculating the pagerank of each peer by its reputation, in which the relationship between peers is introduced as the equivalent to the link between Web pages. The distributed calculation of pagerank is performed asynchronously by each peer as it communicates with the other peers. The asynchronous calculation accomplishes both demanding no extra messages for the calculation of pagerank and steadily calculating an accurate pagerank of each peer even under the dynamic topology of relationships. The result of the simulation has indicated that the calculated pagerank value of each peer converges at the original pagerank value under the static topology of relationships, which is presumable under a dynamic topology. A fully implemented application of distributed pagerank has also been presented, which supports dynamic formation of communities with reputation ranking.

关键词： Peer to peer computing Mathematical model Web pages Network topology Telecommunication network reliability Technological innovation Laboratories Mathematics Physics Informatics

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