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2010 International Conference on Field-Programmable Technology, FPT'10

作者： Wu, Guiming Dou, Yong Wang, Miao National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China Jiangnan Institute of Computing Technology Wuxi 214083 China

ISBN: (纸本)9781424489817

In this paper, we present an automatic synthesis framework to map loop nests to processor arrays with local memories on FPGAs. An affine transformation approach is firstly proposed to address space-time mapping problem. Then a data-driven architecture model is introduced to enable automatic generation of processor arrays by extracting this data-driven architecture model from transformed loop nests. Some techniques including memory allocation, communication generation and control generation are presented. Synthesizable RTL codes can be easily generated from the architecture model built by these techniques. A preliminary synthesis tool is implemented based on PLUTO, an automatic polyhedral source-to-source transformation and parallelization framework. © 2010 IEEE.

关键词： Field programmable gate arrays (FPGA)

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Window memory accesses method in alternate row/column matrix access systems

Window memory accesses method in alternate row/column matrix...

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2010 2nd International Conference on Computer Engineering and Technology, ICCET 2010

作者： Jie, Zhou Dou, Yong Lei, Yuanwu Dong, Yazhuo National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China Unit 91655 People's Republic of China Beijing China

ISBN: (纸本)9781424463503

Many systems, such as Synthetic Aperture Radar (SAR) processing, two-dimensional image processing, 2d-FFT calculation, need access the row and column data of their matrix alternately. The DRAM memory should be used due to huge data in these systems. To improve the usage of memory bandwidth in such systems, this paper theoretically analyses the optimal window size to minimize the total number of opening/closing pages when performing in such instances by balancing the number of handling physical pages between row and column accesses. This paper presents a window-based optimal memory access method, and we implemented an FPGA-based SDRAM controller with eight simple ports, which is based on window accessing mechanism and supports commercialized SDARM. The experimental results show that the effective I/O bandwidth of external SDRAM using our window layout approach increases from 114.2MB/s of naive implementation to 730.2MB/s with over 6X speedup. In addition, we implemented two SAR processing systems with four FFT processing elements using our window-based SDRAM controller and Corner Turn method separately in FPGA chip. Results show window-based method can achieve a speedup of 2.6 compared to Corner Turn method. © 2010 IEEE.

关键词： Fast Fourier transforms

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A distributed Approach to Consistent Order Delivery of Concurrent Events in Asynchronous DVEs

A Distributed Approach to Consistent Order Delivery of Concu...

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2010 2nd International Conference on Education Technology and Computer(第二届IEEE教育技术与计算机国际会议 ICETC 2010)

作者： Hangjun Zhou Wei Zhang Yuxing Peng Sikun Li Key Laboratory of Science and Technology for National Defence of Parallel and Distributed Processing Key Laboratory of Science and Technology for National Defence of Parallel and Distributed Processing

ISBN: (纸本)9781424463671;9781424463688;9781424463701

In large-scale asynchronous distributed virtual environments(DVEs), one of the difficult problems is to deliver the concurrent events in a consistent order at each node. Generally, the previous consistency control approaches can be classified into two categories: causal order and time stamped order. However, causal order approaches can merely preserve the cause-effect relation of events and time stamped order approaches seem intrinsically complex to be used in serverless large-scale asynchronous DVEs. In this paper, we proposed a novel distributed algorithm to identify the concurrent events and preserve the consistent order delivery of them at different nodes. Simulation studies are also carried out to compare the performance of this algorithm with that of the previous ones. The results show that the new algorithm can effectively deliver the concurrent events in consistent order at each node and is more efficient than the previous algorithms in large-scale asynchronous DVEs.

关键词： distributed virtual environments concurrent events distributed consistency algorithm

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Media Access Control Protocol Based on Hybrid Antennas in Ad Hoc Networks

Media Access Control Protocol Based on Hybrid Antennas in Ad...

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Symposia and Workshops on Ubiquitous, Autonomic and Trusted Computing, UIC-ATC

作者： Yanrong Ding Xiaodong Wang Hu Shen Pengyu Guo National Key Laboratory for Parallel and Distributed Processing Changsha China

Nested Circular Directional MAC, a modified medium access control protocol of DMAC protocol, is proposed in this paper to support both directional antennas and omni-directional antennas simultaneously in one Ad Hoc network. Omni-directional antennas follow the RTS/CTS mechanism which is multi-hop and directional antennas follow the DRTS/DCTS mechanism, ensuring the asymmetric communication effectively. In order to resolve new deafness problem and hidden terminal problem, the directional antennas also use circular DRTS and nested antenna circumrotation. Simulation results show that NCDMAC supports hybrid antennas effectively and is better than MMAC and Circular-MAC in terms of increasing throughput, but it also increases the communication delay.

关键词： Delay Deafness Directive antennas Throughput Directional antennas Media Access Protocol

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A load balancing-supported constant degree DHT ID assignment method

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Tien Tzu Hsueh Pao/Acta Electronica Sinica 2010年第11期38卷 2649-2654页

作者： Wang, Xiao-Hai Peng, Yu-Xing Li, Dong-Sheng Key Laboratory of Science and Technology for Parallel and Distributed Processing National University of Defense Technology Changsha Hunan 410073 China

A Load Balancing-Supported ID assignment method is the foundation to implement and maintain DHT overlays, realized constant degree DHTs usually use simple pure centralized or distributed ID management strategies, which cannot resolve the contradiction between cost of maintaining topologies' information and topologies' balance. Analyzing the universal tree structures in the topologies, an ID Assignment method RFIDAM based on the internal structure Routing Forest is proposed, which regularly aggregates local balancing information to guide new nodes' joining for overall balance. The experimental results show, with low maintenance and routing message overhead, the system's loading balance is efficiently ensured with the length of IDs differ by at most 2.

关键词： Topology

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Implementation of encrypted data for outsourced database

Implementation of encrypted data for outsourced database

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2010 2nd International Conference on Computational Intelligence and Natural Computing, CINC 2010

作者： Wang, Zheng-Fei Tang, Ai-Guo Department of Computer Hunan Business College Changsha 410205 China National Key Laboratory for Parallel and Distributed Processing School of Computer National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9781424477036

Encryption technology has become an important mechanism of securing data stored in the outsourced database. However, it is a difficulty to query efficiently the encrypted data and many researchers take it into consideration. To solve the problem, an encrypted schema, based on the Postgresql DBMS, is proposed Through the security dictionary and the extended SQL, the approach implements the encrypted storage and efficiently query over the encrypted data in the outsourced databases. Results of experiments validate the efficiency and feasibility of our approach. ©2010 IEEE.

关键词： Cryptography

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The composability problem of events and threads in distributed systems

ICETC 2010 - 2010 2nd International Conference on Education ...

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ICETC 2010 - 2010 2nd International Conference on Education Technology and Computer 2010年 4卷 V4311-V4315页

作者： Li, Huiba Peng, Yuxing Lu, Xicheng National Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9781424463688

Event-driven programming has been a relatively hot topic in distributed systems development. Having worked on these systems for years, we now believe that it is not the best choice. Besides the well-known "stack ripping" problem, we argue that it greatly influences the composability of software modules. Preemptive threads are also short of composability because of data-races and locks. Lacking of composability can result in systems with little vitality. Cooperative threading (or coroutine), on the contrary, is almost free of this problem, so we advocate it as the primary concurrency model for most distributed systems. © 2010 IEEE.

关键词： distributed computer systems

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Simulation research of communication networks based on prim algorithm

Simulation research of communication networks based on prim ...

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International Forum on Information Technology and Applications

作者： Yang, Chenghui Ren, ChuanJun College of Electrical Engineering Northwest University for Nationalities Lanzhou 730030 China National Laboratory for Parallel and Distributed Processing College of Computer Science National University of Defense Technology Changsha 410073 China

ISBN: (纸本)9780769541150

In order to improve the efficiency of the communication networks, we used the Kruskal algorithm and the Prim algorithm through algorithm comparison and analysis methods of data structure. A dynamic framework for the communication network installed system is built. Moreover, according to the actual framework of the communication network specific issues, the module chooses the Minimum Cost Spanning Tree Prim algorithm ultimately. The assumptions process and outcomes simulation have proper analysis and certification by C language. Experimental results show that the Minimum Cost Spanning Tree of Prim algorithm on the installed system for communication networks dynamic planning process have the advantage of speed and effectively reduce the waste of resources, which not only can ensure efficiency but also can effectively improve communication networks installed cost. © 2010 IEEE.

关键词： Costs

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Two improved GPU acceleration strategies for force-directed graph layout

Two improved GPU acceleration strategies for force-directed ...

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International Conference on Computer Application and System Modeling (ICCASM)

作者： Yong-Xian Wang Zong-Zhe Li Lu Yao Wei Cao Zheng-Hua Wang National Key Laboratory of Parallel and Distributed Processing National University of Defense Technology Changsha China National Key Laboratory for Parallel and Distributed Processing National University of Defense Technology Changsha China

Force directed approach is one of the most widely used methods in graph drawing research. However, the running time is increased intolerablely along with the enlargement of the graph size, which restricts the algorithm's practicability. By the aid of GPU (graphics processing unit) computing platform, we can speed-up the graph layout with low cost, but the existing GPU implementation mainly employees an “one-by-one” style to update the vertex' coordination per iteration, which has a lower convergent rate than the “batch” style which is instead used commonly in traditional CPU implementation. As a result, the aesthetics of graph layout would be decreased if the total running time is restricted. It is hard to achieve both a high speedup factor of GPU over CPU and a high convergent rate in existing GPU computing implementation. In order to solve this problem partially, this paper presents two new strategies to implement the large-scale graph layout on CPU+GPU heteromerous platform to accelerate the force directed layout for graph drawing problem. The numerical computation results show that our GPU implementation can dramatically improve the performance of force-direct layout and is 20 times on a NVIDIA GeForce 9800 GT GPU at 1.44 GHz faster than the one on single-CPU core of Intel Pentium 4 PC at 3.0 GHz for the graph layout with moderate size (typically 1000 vertices).

关键词： Graphics processing unit Gallium nitride Heating

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Improving cluster computing performance based on job futurity prediction

Improving cluster computing performance based on job futurit...

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International Conference on Advanced Computer Theory and Engineering, ICACTE

作者： Hossein Salami Hamid Saadatfar Farhad Rahmani Fard S. Kazem Shekofteh Hossein Deldari Parallel and Distributed Processing Laboratory Engineering Department Ferdowsi University of Mashhad Mashhad Iran

By recognizing the necessity for preventative and proactive management for today's large scale and fault prone distributed systems, a tendency for these mechanisms has been appeared in recent researchers' efforts. From the birth point of this opinion, event prediction has been known as an effective approach to manage errors preventively. In this work, we attempt to make system performance better by using a job futurity predictor as an advisor for system scheduler. We have a clear sighted vision of failure sources and therefore use a comprehensive data set of system, user and job domains. Using predictor results leads to a significant improvement in performance metrics.

关键词： Computational modeling Measurement Middleware

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