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IEEE Power engineering Society Conference and Exposition in Africa, PowerAfrica

作者： G.K. Venayagamoorthy Y. del Valle S. Mohagheghi W. Qiao S. Ray R.G. Harley D.M. Falcao G.N. Taranto T.M.L. Assis Real-Time Power and Intelligent Systems Laboratory Department of Electrical and Computer Engineering University of Missouri Rolla MO USA School of Electrical and Computer Engineering Georgia Institute of Technology Atlanta GA USA University of KwaZulu-Natal Durban South Africa Engenharia Electrica Universidade Federal de Rio de Janeiro Rio de Janeiro Brazil

Flexible AC transmission systems (FACTS) devices are power electronics based shunt or series devices that are connected to the power network and can improve the system performance and the quality of supply. Application of three types of FACTS devices, a STATCOM, a SCRC and a UPFC, is studied in a 45 bus multimachine power system, as part of the Brazilian power system. The system is exposed to various transient and dynamic disturbances, and the performance of the system reinforced with the FACTS devices is compared with the original system. Simulation results are provided that indicate the effectiveness of these FACTS devices in the overall system behaviour

关键词： Power system dynamics Automatic voltage control Power systems Power system transients Power system simulation Flexible AC transmission systems Power transmission lines PSCAD Power electronics Circuit faults

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Two-level preconditioning techniques for electromagnetic wave scattering problems

Two-level preconditioning techniques for electromagnetic wav...

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IEEE/ACES International Conference on Wireless Communications and Applied Computational Electromagnetics

作者： Jeonghwa Lee Jun Zhang Cai-Cheng Lu RAPT Industries Inc. Freeport PA USA Laboratory for High Performance Scientific Computing and Computer Simulation Department of Computer Science University of Kentucky Lexington KY USA Department of Electrical and Computer Engineering University of Kentucky Lexington KY USA

ISBN: (纸本)0780390687

We investigate preconditioned iterative solutions of large dense complex valued matrices arising from discretizing the hybrid integral equations of electromagnetic scattering. Due to the specific data pattern, we propose to construct two-level (TL) preconditioners to treat the conducting and dielectric parts more efficiently. The main purpose of this study is to show that the TL preconditioning is effective with the MLFMA and can reduce the number of Krylov iterations substantially by using subdivided domain of the near part matrix for each level. Our experimental results indicate that the TL preconditioning maintains the computational complexity of the MLFMA, but converges much faster, thus effectively reduces the overall simulation time for the coated material objects.

关键词： Electromagnetic scattering

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Optimizing collective communications on SMP clusters

Optimizing collective communications on SMP clusters

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International Conference on Parallel Processing (ICPP)

作者： Meng-Shiou Wu R.A. Kendall K. Wright Department of Electrical and Computer Engineering Scalable Computing Laboratory U.S. DOE Iowa State University Ames IA USA Scalable Computing Laboratory Ames Laboratory U.S. DOE Iowa State University Ames IA USA Department of Computer Science Scalable Computing Laboratory Ames Laboratory U.S. DOE Iowa State University Ames IA USA

We describe a generic programming model to design collective communications on SMP clusters. The programming model utilizes shared memory for collective communications and overlapping inter-node/intra-node communications, both of which are normally platform specific approaches. Several collective communications are designed based on this model and tested on three SMP clusters of different configurations. The results show that the developed collective communications can, with proper tuning, provide significant performance improvements over existing generic implementations. For example, when broadcasting an 8 MB message our implementations outperform the vendor's MPl/spl ***/Bcast by 35% on an IBM SP system, 51% on a G4 cluster, and 63% on an Intel cluster, the latter two using MPICH's MPl/spl ***/Bcast. With all-gather operations using 8 MB messages, our implementation outperform the vendor's MPI/spl ***/Allgather by 75% on the IBM SP, 60% on the Intel cluster, and 48% on the G4 cluster.

关键词： Laboratories US department of Energy Clustering algorithms Design optimization computer science Communication networks Testing Broadcasting Pipelines Parallel architectures

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Adaptive approach for QoS support in IEEE 802.11e wireless LAN

Adaptive approach for QoS support in IEEE 802.11e wireless L...

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IEEE International Conference on Wireless and Mobile computing, Networking And Communications (WiMob)

作者： J. Naoum-Sawaya B. Ghaddar S. Khawam H. Safa H. Artail Z. Dawy Department of Electrical and Computer Engineering American University of Beirut Beirut Lebanon Mobile Computing and Networking Research Laboratory (LARIM) Ecole Polytechnique de Montreal Montreal Canada Department of Computer Science American University of Beirut Beirut Lebanon

the IEEE 802.11e standard has been introduced recently for providing quality of service (QoS) capabilities in the emerging wireless local area networks. This standard introduces a contention window based enhanced distributed channel access (EDCA) technique that provides a prioritized traffic to guarantee the minimum bandwidth needed for time critical applications. However, the EDCA technique resets statically the contention window of the mobile station after each successful transmission. This static behavior does not adapt to the network state hence reduces the network usage and results in bad performance and poor link utilization whenever the demand for link utilization increases. This paper proposes a new adaptive differentiation technique for IEEE 802.11e wireless local area networks that takes into account the network state before resetting the contention window. The performance of the proposed technique is evaluated compared to the original differentiation techniques of the IEEE 802.11a and IEEE 802.11e standards. Preliminary results show that the proposed adaptive technique enhances the channel utilization and increases throughput.

关键词： Wireless LAN Quality of service Bandwidth Intelligent networks Telecommunication traffic Throughput Helium Local area networks IP networks Delay

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I/O profiling for distributed IP storage systems

I/O profiling for distributed IP storage systems

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International Conference on Embedded Software and Systems

作者： Jizhong Han Dan Zhou Xubin He Jinzhu Gao Institute of Computing Technology Chinese Academy and Sciences Beijing China Department of Electrical & Computer Engineering Tennessee Technological University Cookeville TN USA Computer Science & Mathematics Division Oak Ridge National Laboratory Oak Ridge TN USA

The popularity of Web services demands data storage over the network. iSCSI is a newly emerging protocol with the goal of deploying storage over the mature TCP/IP in an economic and convenient way. In a typical Web service using iSCSI storage systems, I/O requests issued by Web users can be satisfied by different parties, such as client cache, proxy cache, Web server cache, iSCSI target cache, and disks, along the I/O path from Web clients to iSCSI storage. Understanding the characteristics of I/O traffic under such environment is increasingly important as the networked storage prevails. This paper profiles I/O for Web services using iSCSI storage systems and identifies how these I/O requests are distributed and satisfied. Both simulation and benchmarking results show that the I/O profiling is helpful to identify I/O performance bottleneck of Web services and helps to improve iSCSI performance.

关键词： Web services IP networks TCPIP Cache storage Memory Protocols Web server Storage area networks Web and internet services Telecommunication traffic

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Journal of Information science and engineering: Editorial notice

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Journal of Information science and engineering 2005年第5期21卷 i-ii页

作者： Lee, Der-Tsai Amato, Nancy M. Chang, Shih-Fu Chen, Homer H. Chen, Tsuhan Hsu, Tsan-Sheng Hwang, Jenq-Neng Kuo, Sy-Yen Kuo, Tei-Wei Li, Chung-Sheng Tokuyama, Takeshi Wing, Jeannette Wu, Tzong-Chen Yen, John Computer Science at Texas A and M University United States Parasol Laboratory United States IEEE Transactions on Parallel and Distributed Systems Computing Research Association's Committee on the Status of Women in Computing Research CRA-W's Distributed Mentor Program United States Department of Electrical Engineering Columbia University United States Lab. United States College of Electrical Engineering and Computer Science National Taiwan University Taiwan IEEE Transactions on Circuits and Systems for Video Technology IEEE Department of Electrical and Computer Engineering Carnegie Mellon University Pittsburgh PA United States ACM ACM SIGACT IEEE Computer Society IICM Austria Research and Development of the Department Multimedia Signal Processing Technical Committee IEEE Signal Processing Society United States IEEE Transactions on Circuits and systems for Video Technology College of Electrical Engineering and Computer Science National Taiwan Ocean University Keelung Taiwan Department of Electrical Engineering National Taiwan University Taiwan Department of Computer Science and Information Engineering National Taiwan University Taipei Taiwan IEEE Technical Committee on Real-Time Systems Computer Science Division IBM T.J. Watson Research Center United States IBM Research Division Graduate School of Information Sciences Tohoku University Japan ACM IPSJ Mathematical Society of Japan Japan Department of Computer Science Computer Science Department Carnegie Mellon University United States National Academies of Science's Computer Science and Telecommunications Board United States Microsoft's Trustworthy Academic Advisory Board Intel Research Pittsburgh's Advisory Board United States Dartmouth's Institute for Security Technology Studies Advisory Committee Canada Sloan Research Fellowships Program Committee United States ACM Taiwan China Information Sciences and Technology Pennsylvania State University United States Laboratory for Intelligent Agents Penn State's School of Info

No abstract available

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real time head tracking via camera saccade and shape-fitting

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2nd International Conference on Image Analysis and Recognition, ICIAR 2005

作者： Zhang, Jason Z. Lu, Ye Wu, Q.M. Jonathan Micro-technology and Sensing Group Institute for Fuel Cell Innovation National Research Council of Canada Vancouver BC V6T 1W5 Canada Vision and Media Laboratory School of Computing Science Simon Fraser University Burnaby BC V5A 1S6 Canada Department of Electrical and Computer Engineering University of Windsor Ont. N9B 3P4 Canada

ISBN: (纸本)3540290699

This paper presents a system that tracks human heads in real-time under unconstrained environments where target occlusion, varying illumination, and cluttered backgrounds exist. Tracking is formulated as an active visual servo problem based on the integration of a saccade and a smooth pursuit processes. The head is modelled as an ellipse computed from the color clusters of candidate targets using a robust least square ellipse fitting algorithm. The Farnsworth Perceptually Uniform Color Model is employed to represent the color information of the visual objects. Kalman filtering is applied to the head ellipse to track the evolution of the position, size, and orientation of the target such that the occlusion of objects with similar color and shape as those of the target are effectively accommodated. Experiments with tracking scenarios demonstrate the effectiveness of the system. © Springer-Verlag Berlin Heidelberg 2005.

关键词： Tracking (position)

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LiSP: A Lightweight Security Protocol for Wireless Sensor Networks

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ACM Transactions on Embedded computing Systems 2004年第3期3卷 634-660页

作者： Park, Taejoon Shin, Kang G. Real-Time Computing Laboratory (RTCL) Department of Electrical Engineering and Computer Science The University of Michigan Ann Arbor MI 48109-2122 United States

Small low-cost sensor devices with limited resources are being used widely to build a self-organizing wireless network for various applications, such as situation monitoring and asset surveillance. Making such a sensor network secure is crucial to their intended applications, yet challenging due to the severe resource constraints in each sensor device. We present a lightweight security protocol (LiSP) that makes a tradeoff between security and resource consumption via efficient rekeying. The heart of the protocol is the novel rekeying mechanism that offers (1) efficient key broadcast without requiring retransmission/ACKs, (2) authentication for each key-disclosure without incurring additional overhead, (3) the ability of detecting/recovering lost keys, (4) seamless key refreshment without disrupting ongoing data encryption/decryption, and (5) robustness to inter-node clock skews. Furthermore, these benefits are preserved in conventional contention-based medium access control protocols that do not support reliable broadcast. Our performance evaluation shows that LiSP reduces resource consumption significantly, while requiring only three hash computations, on average, and a storage space for eight keys. © 2004, ACM. All rights reserved.

关键词： Authentication Design key management lightweight security Security sensor networks

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Integrated modeling and analysis of automotive embedded control systems with real-time scheduling

Integrated modeling and analysis of automotive embedded cont...

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2004 SAE World Congress

作者： Gu, Zonghua Wang, Shige Kim, Jeong Chan Shin, Kang G. Real-Time Computing Laboratory Electrical Engineering and Computer Science Dept. University of Michigan Ann Arbor MI 48109 United States

ISBN: (纸本)0768013194

As the complexity of automotive embedded software grows, it is desirable to bring as much automation into the development process as possible, as evidenced by efficient code generators from modeling tools such as Simulink. However, the current development process does not pay enough attention to non-functional issues such as real-time requirements. Modeling tools such as Simulink do not allow representation of the target platform, so it is not possible to analyze real-time behavior in the early design stage. The typical approach is to download the executable to the target micro-controller and measure to see if there are any missed deadlines. We describe a tool that can be used to model system-level software and hardware architectures and analyze system timing behavior at early design stages, and assess the impact of the target platform on control system performance. Copyright © 2004 SAE International.

关键词： Simulink

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On soft real-time guarantees on ethernet

On soft real-time guarantees on ethernet

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9th International Conference on real-time and Embedded computing Systems and Applications, RTCSA 2003

作者： Cho, Min-gyu Shin, Kang G. Real-Time Computing Laboratory Department of Electrical Engineering and Computer Science The University of Michigan Ann ArborMI48109-2122 United States

ISBN: (纸本)9783540246862

The medium access protocol of Ethernet, CSMA/CD, has an inherent limitation in providing real-time guarantees. Since Ethernet is the most commonly used local area network (LAN) technology due to its low cost, high bandwidth and robustness, it is very important to overcome this problem so that Ethernet can be used as a network for soft real-time applications like multimedia. An adaptive traffic smoother (ATS) was proposed as a kernel-level software solution that provides soft real-time guarantees on Ethernet. This paper addresses the reconfigurability, scalability and portability of ATS. First, a mechanism to read and adjust several user-specific parameters of ATS is discussed, and metrics or parameters to indicate the achievement of the user-required Quality-of-Service (QoS) are developed since these parameters are indirectly related to the user-specific QoS. Our experimental evaluation validates the feasibility of enhancing the reconfigurability and portability of ATS. Second, ATS is extended to a switched Ethernet which is commonly used for scalability. Our solution employs an ATS for each port of the switch for real-time packet delivery guarantees. Finally, a prototype of the user-level ATS is implemented and evaluated to enhance the portability of ATS. The performance of this user-level ATS is shown to be comparable to that of the kernel-level implementation, while enhancing both the reconfigurability and portability of real-time Ethernet solutions. © Springer-Verlag Berlin Heidelberg 2004.

关键词： Ethernet

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