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IEEE/ACM International Symposium on Cluster Computing and the Grid (CCGRID)

作者： A. Mitra R. Udupa M. Maheswaran Department of Computer Science University of Manitoba Canada Department of Elec. & Computer Engineering McGill University Canada School of Computer Science McGill University Canada

ISBN: (纸本)9780780390744

Trust and security are two major issues in large distributed systems that are highly inter-dependent such that it is hard to bootstrap one without the other. In distributed systems that are built using private resources, security is bootstrapped using off-line trust relationships. Mandating off-line trust relations, however, has the undesirable effect of limiting the membership of distributed systems. Therefore, public-resource based systems need online trust modeling. This paper presents a two-layered framework that considers trust, security and incentives in an integrated fashion. Our framework is characterized by (a) a community-based process that is essentially decentralized for evaluating and assigning trust for peers (b) policy autonomy in administering incentives and trust, and (c) lowers the join time trust requirements for peers. Results from early prototyping and simulations show the proposed framework can be implemented with acceptable overheads and is capable of evolving trust and applying it for resource management.

关键词： Resource management Radio access networks Peer to peer computing computer science computer security computer architecture Identity management systems Virtual prototyping Computational modeling Distributed computing

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Supporting emotional ties among Mexican elders and their families living abroad

Supporting emotional ties among Mexican elders and their fam...

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Conference on Human Factors in Computing Systems, CHI EA 2005

作者： Santana, Pedro C. Rodríguez, Marcela D. González, Víctor M. Castro, Luís A. Andrade, Ángel G. Faculty of Engineering UABC University Mexico Computer Science Depart CICESE Research Center Ensenada Mexico Elec. and Telecomm. Depart CICESE Research Center Ensenada Mexico Department of Informatics University of California Irvine United States

ISBN: (纸本)1595930027

The aging of the population is a phenomenon faced by most nations, such as Mexico, where 7.5% of the population is older than 60 years, a significant proportion of whom live alone (10%). This fact is related with the ever increasing migration of one or more of their relatives, mostly to the USA. Our work aims to provide a technological solution that eases the isolation of elder people living alone in Mexico while their families are abroad. To envision and inform our design we interviewed independent old persons living alone. We propose an electronic family newspaper, through which elders and their families share information, personal reminiscences and cultural stories, and occasionally interact with each other. Through its functionality, the electronic newspaper enables elders not only to maintain close social ties, but ameliorate cognitive decline.

关键词： Newsprint

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On the improvement of rotational invariance of Zernike moments

On the improvement of rotational invariance of Zernike momen...

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IEEE International Conference on Image Processing

作者： Yongqing Xin S. Liao M. Pawlak Department Elec. & Computer Engineering University of Manitoba Winnipeg MAN Canada Department Applied Computer Science University of Winnipeg Winnipeg MAN Canada

Zernike moment (ZM) is a useful image feature because of its distinguishing properties such as the magnitude invariance to image rotation. However, we find that for digital images, the invariant property of ZMs is far from ideal when they are computed with the commonly used Cartesian method, which inevitably brings about geometric error and integral error. In this paper, we propose a polar coordinate based algorithm for the computation of ZMs, which avoids both kinds of errors. We provide solutions to the key issues in ZM computation under polar coordinate system, including the derivation of computation formulas, the polar pixel arrangement scheme, and the interpolation-based image conversion etc. Simulation results show that the proposed polar approach improves the rotational invariance of ZMs significantly.

关键词： Digital images Polynomials Approximation error computer science Pixel Image converters Computational modeling Image analysis Pattern recognition Image processing

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ROI Medical Image Watermarking Using DWT and Bit-plane

ROI Medical Image Watermarking Using DWT and Bit-plane

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Asia-Pacific Conference on Communications

作者： Hyung-Kyo Lee Hee-Jung Kim Ki-Ryong Kwon Jong-Keuk Lee Department of Internet Business Andong Science College Department of Elec and Computer Engineering Pusan University of Foreign Studies South Korea Department of Computer Engineering Dongeui University South Korea

ISBN: (纸本)0780391322

Recently, the medical image has been digitized by the development of computer science and digitization of the medical devices. There are needs for database service of the medical image and long term storage because of the construction of PACS (picture archiving and communication system) following DICOM (digital imaging communications in medicine) standards, tele-medicine, and et al. Furthermore, authentication and copyright protection are required to protect the illegal distortion and reproduction of the medical information data. In this paper, we propose digital watermarking technique for medical image that prevents illegal forgery that can be caused after transmitting medical image data remotely. A wrong diagnosis may be occurred if the watermark is embedded into the whole area of image. Therefore, we embed the watermark into some area of medical image, except the decision area that makes a diagnosis so called region of interest (ROI) area in our paper, to increase invisibility. The watermark is the value of bit-plane in wavelet transform of the ROI for integrity verification. The experimental results show that the watermark embedded by the proposed algorithm can survive successfully in image processing operations such as JPEG lossy compression

关键词： Biomedical imaging Watermarking Discrete wavelet transforms Medical diagnostic imaging Image storage Picture archiving and communication systems computer science Image databases DICOM Digital images

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Fine-grained dynamic voltage and frequency scaling for precise energy and performance tradeoff based on the ratio of off-chip access to on-chip computation times

Fine-grained dynamic voltage and frequency scaling for preci...

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作者： Choi, Kihwan Soma, Ramakrishna Pedram, Massoud Samsung Electronics Corporation Seoul Korea Republic of Dept. of Elec. Engineering Systems University of Southern California Los Angeles CA 90089 United States Department of Computer Science University of Southern California Los Angeles CA 90089 United States

This paper presents an intraprocess dynamic voltage and frequency scaling (DVFS) technique targeted toward nonreal-time applications running on an embedded system platform. The key idea is to make use of runtime information about the external memory access statistics in order to perform CPU voltage and frequency scaling with the goal of minimizing the energy consumption while translucently controlling the performance penalty. The proposed DVFS technique relies on dynamically constructed regression models that allow the CPU to calculate the expected workload and slack time for the next time slot and, thus, adjust its voltage and frequency in order to save energy, while meeting soft timing constraints. This is, in turn, achieved by estimating and exploiting the ratio of the total off-chip access time to the total on-chip computation time. The proposed technique has been implemented on an XScale-based embedded system platform and actual energy savings have been calculated by current measurements in hardware. For memory-bound programs, a CPU energy saving of more than 70% with a performance degradation of 12% was achieved. For CPU-bound programs, 15% ∼ 60% CPU energy saving was achieved at the cost of 5%-20% performance penalty.

关键词： Embedded systems

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Optimal packetization of fine granularity scalability codestreams for error-prone channels

Optimal packetization of fine granularity scalability codest...

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IEEE International Conference on Image Processing

作者： B.B. Zhu Yang Yang Chang Wen Chen Shipeng Li Microsoft Research Asia Beijing China Department of Elec. Engineering & Info Sci University of Science and Technology Hefei Anhui China Department of Elec. and Computer Engineering Florida Institute of Technology Melbourne FL USA

An optimal source-channel packetization scheme for MPEG-4 fine granularity scalability (FGS) codestreams is proposed in this paper. The channel is modeled with a uniform error distribution to the enhancement layer transmission. A cost function that models the error expansion for a MPEG-4 FGS stream is derived, and then used in the optimal packetization problem subject to the same overhead as the conventional packetization scheme. An efficient scheme to find the optimal solution is described, which takes time similar to encoding an MPEG-4 FGS codestream. Experiments show that our scheme has up to 1.96 dB gain over the conventional packetization scheme.

关键词： Scalability MPEG 4 Standard Streaming media Decoding computer errors Bandwidth Video compression Asia Cost function Gain

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Parallel matrix-multiplication algorithm for distributed parallel computers

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Systems and computers in Japan 2005年第4期36卷 48-59页

作者： Hattori, Masamitsu Ito, Nobuhiro Chen, Wei Wada, Koichi Mitsubishi Electric Corporation Nagoya Works Nagoya 461-8670 Japan Dept. of Elec. and Comp. Engineering Nagoya Institute of Technology Nagoya 466-8555 Japan Department of Computer Science Tennessee State University Nashville TN 37205 United States Dept. of Info. and Telecom. Eng. Nanzan University Seto 489-0863 Japan

This paper proposes a matrix-multiplication algorithm suited to the distributed computer environment. The system is implemented using PVM and the execution time is evaluated. One of the conventional methods implemented using PVM is the systolic method. However, this method is limited with respect to the matrix size that can be calculated and the number of computers that can be used in the calculation. This paper first extends the algorithm so that these limitations are lifted. Then, an algorithm is proposed which can reduce the communication complexity, although the computational complexity is slightly increased. These two algorithms are implemented using PVM, and the execution time is measured. In either algorithm, an acceleration rate exceeding the number of computers is obtained. The effectiveness is found to be due to the effect of the cache memory, and the speed improvement obtained by using cache memory is investigated. The optimal number of matrix divisions from the viewpoint of cache memory size is also discussed. © 2005 Wiley Periodicals, Inc.

关键词： Parallel processing systems

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A parallel implementation of the message-passing decoder of LDPC codes using a reconfigurable optical model

A parallel implementation of the message-passing decoder of ...

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ACIS International Conference on Software engineering, Artificial Intelligence, Networking, and Parallel/Distributed Computing (SNPD)

作者： S. Babvey A.G. Bourgeois J.A. Fernandez-Zepeda S.W. McLaughlin Department of Computer Science Georgia State University Atlanta GA USA Department of Computer Science CICESE Mexico School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA School of Elec. and Compo Engineering Georgia Institute of Technology Atlanta GA

In this paper we propose a constant-time algorithm for parallel implementation of the message-passing decoder of low density parity check (LDPC) codes on the linear array with a reconfigurable pipelined bus system (LARPBS), achieving the minimum number of processors required for a fully parallel implementation. Dynamic reconfiguration provides flexibility to code changes and efficient message routing. To decode a different code, we may simply set up the required connections between the bit-nodes and check-nodes by modifying the initialization phase of the LARPBS algorithm. No extra wiring or hardware changes are required, as compared to other existing approaches. Moreover, the same hardware can implement the decoder in both probability and logarithm domains. The LARPBS also allows reducing the number of the bus cycles required for processor communications to a small constant, regardless of the code length. We illustrate that the LARPBS is an efficient and fast model for implementing the decoder.

关键词： Parity check codes Hardware Iterative decoding computer science Signal to noise ratio Optical arrays Routing Wiring Optical noise Error correction

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An efficient R-Mesh implementation of LDPC codes message-passing decoder

An efficient R-Mesh implementation of LDPC codes message-pas...

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International Symposium on Parallel and Distributed Processing (IPDPS)

作者： S. Babvey A.G. Bourgeois J.A. Fernandez-Zepeda S.W. McLaughlin Department of Computer Science Georgia State University Atlanta GA Department of Computer Science CICESE Ensenada B. C. Mexico School of Elec. and Comp Engineering Georgia Institute of Technology Atlanta GA

In this paper we propose a constant-time parallel algorithm for implementing the message-passing decoder of LDPC codes on a two dimensional R-Mesh, trying to keep the number of processors small. The R-Mesh provides dynamic reconfiguration, hardware reuse, and flexibility to problem changes. To decode a different code, we may simply set up the required connections between the bit-nodes and check-nodes by modifying the initialization phase of the R-Mesh algorithm. No extra wiring or hardware changes are required, as compared to other existing approaches. Moreover, the same hardware can implement the decoder in both probability and logarithm domains. We illustrate that the R-Mesh is an efficient model for parallel implementation of the decoder in terms of time complexity, flexibility to problem changes and simplicity of routing messages.

关键词： Parity check codes Hardware Iterative decoding Parallel architectures computer science Parallel algorithms Signal to noise ratio Digital video broadcasting Wireless LAN Field programmable gate arrays

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Measuring scalability of resource management systems

Measuring scalability of resource management systems

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19th IEEE International Parallel and Distributed Processing Symposium, IPDPS 2005

作者： Mitra, Arindam Maheswaran, Muthucumaru Ali, Shoukat Dept. of Computer Science University of Manitoba Winnipeg Man. R3T 2N2 Canada School of Computer Science McGill University Montreal Que. H3A 2A7 Canada Dept. of Elec. and Comp. Engg University of Missouri-Rolla Rolla MO 65409-0040 United States University of Manitoba Winnipeg Man. Canada School of Computer Science McGill University Montreal Canada Eta Kappa Nu Honorary Society Electrical and Computer Engineering Department University of Missouri-Rolla IEEE IEEE Computer Society ACM

ISBN: (纸本)0769523129

Scalability refers to the extent of configuration modifications over which a system continues to be economically deployable. Until now, scalability of resource management systems (RMSs) has been examined implicitly by studying different performance measures of the RMS designs for different parameters. However, a framework is yet to be developed for quantitatively evaluating scalability to unambiguously examine the trade-offs among the different RMS designs. In this paper, we present a methodology to study scalability of RMSs based on overhead cost estimation. First, we present a performance model for a managed distributed system (e.g., Grid computing system) that separates the manager and managee. Second, based on the performance model we present a metric used to quantify the sealability of a RMS. Third, simulations are used to apply the proposed scalability metric to selected RMSs from the literature. The results show that the proposed metric is useful in quantifying the scalabilities of the RMSs.

关键词： Distributed computer systems

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