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International Joint Conference on Computational sciences and Optimization, CSO

作者： Chuanjun Ren Chenghui Yang Shiyao Jin National Laboratory for Parallel & Distributed Processing College of Computer Science National University of Defense Technology Changsha China National Laboratory for Parallel & Distributed Processinz National University of Defense Technology Changsha China National University of Defense Technology Changsha Hunan CN

The modeling and simulation on evacuation has recently become a topic of great interest. We present an agent-based model to construct crowd evacuations for emergency response from an area under an explosion. Various types of agents are designed as well as the interactions of them are concerned in contrast to traditional models in which the total populations are considered to be consisted of identical individuals and the interactions between them are omitted. Different cases are taken into account to test the effect of our model by iterative simulations. At last, plenty simulation results suggest several effective ways to minimize the harmful consequences of such life-threaten events.

关键词： Explosions Computational modeling Computer simulation Testing Accidents Humans Analytical models Concurrent computing distributed computing distributed processing

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Creating Virtual Networks for distributed Virtual Computing Environment

Creating Virtual Networks for Distributed Virtual Computing ...

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International Conference on parallel and distributed Systems (ICPADS)

作者： Dongsheng Li Yixin Chen Feng Huang National Laboratory of Parallel and Distributed Processing College of Computer National University of Defense Technology Changsha Hunan China

Virtual network is an important approach to support multiple legacy applications running unmodified in distributed virtual computing environments. A virtual networking approach called VirNet is proposed in this paper. VirNet can build multiple customized and isolated virtual networks simultaneously on the same physical hosts in the network, and it enables existing distributed applications written for LANs to run seamlessly on Internet. VirNet is designed completely in user space and requires no change to the kernel of operating systems. Experimental evaluation performed by a reference implementation shows that VirNet is efficient. The latency overhead caused by VirNet is very small and the bandwidth of VirNet is more than 85% of the available physical network bandwidth in both the LAN and emulated WAN environments.

关键词： Computer networks distributed computing Bandwidth IP networks Kernel Operating systems Performance evaluation Delay Local area networks Wide area networks

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Laser-driven inertial ion focusing

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Physical Review E 2009年第1期79卷 015401(R)-015401(R)页

作者： H. B. Zhuo Wei Yu M. Y. Yu H. Xu X. Wang B. F. Shen Z. M. Sheng J. Zhang National Laboratory for Parallel and Distributed Processing School of Computer Science National University of Defense Technology Changsha 410073 China Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Institute for Fusion Theory and Simulation Zhejiang University Hangzhou 310027 China Institute for Theoretical Physics I Ruhr University Bochum D-44780 Germany Department of Physics Jiaotong University Shanghai 200240 China

A Hohlraum-like configuration is proposed for realizing a simple compact source for neutrons. A laser pulse enters a tiny thin-shelled hollow-sphere target through a small opening and is self-consistently trapped in the cavity. The electrons in the inner shell-wall region are expelled by the light pressure. The resulting space-charge field compresses the local ions into a thin layer that becomes strongly heated. An inward expansion of ions into the shell cavity then occurs, resulting in the formation at the cavity center of a hot spot of ions at high density and temperature, similar to that in inertial electrostatic confinement.

关键词： laser fusion neutron sources particle beam focusing ELECTROSTATIC CONFINEMENT FUSION DEVICE

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Program Optimization of Array-Intensive SPEC2k Benchmarks on Multithreaded GPU Using CUDA and Brook+

Program Optimization of Array-Intensive SPEC2k Benchmarks on...

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International Conference on parallel and distributed Systems (ICPADS)

作者： Guibin Wang Tao Tang Xudong Fang Xiaoguang Ren National Laboratory of Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha Hunan China

Graphic processing Unit (GPU), with many light-weight data-parallel cores, can provide substantial parallel computing power to accelerate several general purpose applications. Both the AMD and NVIDIA corps provide their specific high performance GPUs and software platforms. As the floating-point computing capacity increases continually, the problem of ``memory-wall'' becomes more serious, especially for array-intensive applications. In this paper, we optimize and implement two SPEC2k benchmarks mgrid and swim on multithreaded GPU using CUDA and Brook+. In order to reduce the pressure on off-chip memory, we make use of data locality in multi-level memory hierarchies and hide long memory access latency via double-buffers. To balance inter-thread parallelism and intra-thread locality, we further tune thread granularity for each kernel and empirically study the best equilibrium point for this problem. Flow control instruction can significantly impact the effective instruction throughput. Oriented to this problem, we introduce a diverge elimination technology to convert condition expression into computing operation. Through all the optimizations, we gain the speedup of 10×-34× to the CPU implementation on the GPUs of AMD and NVIDIA respectively. Finally, we summarize and compares the GPUs from AMD and NVIDIA in hardware and software.

关键词： parallel processing Application software Graphics Acceleration Software performance Delay Yarn Kernel Throughput Central processing Unit

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Program Optimization of Stencil Based Application on the GPU-Accelerated System

Program Optimization of Stencil Based Application on the GPU...

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International Symposium on parallel and distributed processing with Applications, ISPA

作者： Guibin Wang Xuejun Yang Ying Zhang Tao Tang XuDong Fang National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha Hunan China

Graphic processing Unit (GPU), with many light-weight data-parallel cores, can provide substantial parallel computational power to accelerate general purpose applications. But the powerful computing capacity could not be fully utilized for memory-intensive applications, which are limited by off-chip memory bandwidth and latency. Stencil computation has abundant parallelism and low computational intensity which make it a useful architectural evaluation benchmark. In this paper, we propose some memory optimizations for a stencil based application mgrid from SPEC 2 K benchmarks. Through exploiting data locality in 3-level memory hierarchies and tuning the thread granularity, we reduce the pressure on the off-chip memory bandwidth. To hide the long off-chip memory access latency, we further prefetch data during computation through double-buffer. In order to fully exploit the CPU-GPU heterogeneous system, we redistribute the computation between these two computing resource. Through all these optimizations, we gain 24.2 x speedup compared to the simple mapping version, and get as high as 34.3 x speedup when compared with a CPU implementation.

关键词： Concurrent computing Application software Acceleration Yarn Delay distributed processing distributed computing Bandwidth parallel processing Prefetching

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SEMCS: A Precise Memory-Hierarchy Simulation Framework on parallel Full-System Simulator

SEMCS: A Precise Memory-Hierarchy Simulation Framework on Pa...

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WASE International Conference on Information Engineering, ICIE

作者： Junjie Wu Xiaohui Pan Guanghui Liu Xuejun Yang National Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha Hunan China

The memory wall problem makes researches on memory hierarchy more and more important. And in these researches, software simulation plays a significant role. To model the real runtime environment, full system simulators have been widely used. However, researchers are often perplexed by the precise problem when they run a parallel program on a full system multi-core simulator, especially in multiple configurations. Because the influence arising from operating system and the relative execution speed of parallel threads often make the performance of target programs uncertain. To solve the precise problem, this paper proposes a single execution multi-configuration simulation framework (SEMCS). Then we design and implement a Simics module, called trans-multicast using the SEMCS framework. Finally, we test a benchmark from SPEComp2001 on a four core processor in three memory hierarchy configurations. And the result has verified the effectiveness of the SEMCS framework.

关键词： Computational modeling Operating systems Testing Read-write memory Computer simulation Concurrent computing Yarn Cache memory Laboratories distributed processing

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SCQR - A P2P Query Routing Algorithm Based on Semantic Cluster

SCQR - A P2P Query Routing Algorithm Based on Semantic Clust...

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International Symposium on Intelligent Ubiquitous Computing and Education

作者： Shiyao Jin Gui-Ming Zhu School of Computer Science National University of Defense Technology Changsha China National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China

The low efficiency and uncertainty routing is correct is a problem for resource location of an unstructured p2p network. It is hard to achieve high query hit with small cost and low latency for such kind of network. In this paper, we present a p2p query routing algorithm which is based on semantic cluster (SCQR). SCQR makes nodes clustered according to their semantic, and each cluster elects a super-node as cluster computing node which is responsible for computing cluster semantic and establishing links with all neighbor cluster computing nodes. Query is routed among cluster computing nodes. SCQR achieves high query hit with small routing latency and query cost in both analytical theoretical and experimental studies.

关键词： Query processing Clustering algorithms Peer to peer computing Routing Delay Costs Computer networks Frequency Floods Intelligent networks

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An Optimal Mapping Algorithm Based on Balanced Load Cutting for DVE Systems

An Optimal Mapping Algorithm Based on Balanced Load Cutting ...

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International Symposium on Intelligent Information technology Application, IITA

作者： Wei Zhang Min Xi Hangjun Zhou Yuxing Peng Sikun Li National Laboratory for Parallel and Distributed Processing National University of Defense Technology ChangSha China Department of Computer Science Xi'an Jiaotong University Xi'an China

In distributed virtual environment (DVE) systems, a distributed server infrastructure is often used to reduce the latency between servers and clients. Under this infrastructure, mapping clients to proper servers is one of the key issues for improving the interactivity and overall performance. Most traditional methods of mapping the clients to servers only consider the load balancing problem. However, there are two other important aspects that should be involved: the physical world integrity and the virtual world integrity. In this work, we propose a novel mapping algorithm which takes care of all three aspects at the same time. The algorithm converts the mapping problem into cutting stage and matching stage to get optimal result with polynomial complexity. The experimental results show that our algorithm improves the overall performance of DVE systems significantly.

关键词： Delay Network servers Computer science Virtual environment Load management Polynomials Quality of service Information technology Application software distributed processing

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An incremental learning algorithm for supervised neural network with contour preserving classification

An incremental learning algorithm for supervised neural netw...

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International Conference on Electrical Engineering/Electronics, Computer, Telecommunications and Information technology, ECTI-CON

作者： Piyabute Fuangkhon Thitipong Tanprasert Parallel and Distributed Computing Research Laboratory Faculty of Science and Technology Assumption University Bangkok Thailand

This paper presents an alternative algorithm for integrating the existing knowledge of a supervised learning neural network with the new training data. The algorithm allows the existing knowledge to age out in slow rate as a neural network is gradually retrained with consecutive sets of new samples, resembling the change of application locality under a consistent environment. The algorithm also utilizes the contour preserving classification algorithm to increase the accuracy of classification. The experiment is performed on 2-dimension partition problem and the result convincingly confirms the effectiveness of the algorithm.

关键词： Neural networks Support vector machines Support vector machine classification Supervised learning Partitioning algorithms Neurons Classification algorithms Speech recognition Data mining distributed computing

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Feedback-Based Energy-aware Scheduling Algorithm for Hard Real-time Tasks

Feedback-Based Energy-aware Scheduling Algorithm for Hard Re...

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International Conference on Networking, Architecture, and Storage (NAS)

作者： Dong-song Zhang Shi-yao Jin Tong Wu Hua-wei Li National Laboratory of Parallel and Distributed Processing National University of Defense Technology Changsha China Zhenjiang Watercraft College Jiangsu China

In this paper, we propose a new algorithm for dynamic voltage scaling (DVS) based on feedback control mechanism. Besides handling a periodic tasks, our algorithm significantly reduces the energy consumption of periodic tasks and consequently the energy consumption of the whole task set. The results show that, comparing to on-line dynamic voltage scaling (the best algorithm to our knowledge), our approach improves the energy savings by 10% on most task sets tested and by 5% on average.

关键词： Scheduling algorithm Dynamic voltage scaling Feedback control Processor scheduling Real time systems Energy consumption Voltage control Switches Heuristic algorithms Dynamic scheduling

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