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Embedded DHT overlays in virtual computing environments

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Science china(Information Sciences) 2010年第3期53卷 483-493页

作者： ZHANG YiMing, LU XiCheng & LI DongSheng 1national Laboratory for Parallel and Distributed Processing (PDL), changsha 410073, china 2school of computer, national university of defense technology, changsha 410073, china 1. national Laboratory for Parallel and Distributed Processing (PDL) Changsha 410073 China

With the rapid development of computing and networking technologies, people propose to build harmonious, trusted and transparent Internet-based virtual computing environments (iVCE). The overlay-based organization of dynamic Internet resources is an important approach for iVCE to realizing efficient resource sharing. DHT-based overlays are scalable, low-latency and highly available; however, the current DHT overlay (SKY) in iVCE cannot satisfy the "trust" requirements of Internet applications. To address this problem, in this paper we modify SKY and propose TrustedSKY, an embedded DHT overlay technique in iVCE which supports applications to select trusted nodes to form a "trusted subgroup" in the base overlay and realize secure and trusted DHT routing.

关键词： Internet-based virtual computing environment (iVCE) DHT overlay TrustedSKY

Survey of DHT topology construction techniques in virtual computing environments

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Science china(Information Sciences) 2011年第11期54卷 2221-2235页

作者： ZHANG YiMing 1,2,LU XiCheng 1,2 & LI DongSheng 1,21 national Laboratory for Parallel and Distributed Processing (PDL),changsha 410073,china 2 school of computer,national university of defense technology,changsha 410073,china 1. national Laboratory for Parallel and Distributed Processing (PDL) Changsha 410073 China2. School of Computer National University of Defense Technology Changsha 410073 China

The Internet-based virtual computing environment (iVCE) is a novel network computing *** characteristics of growth,autonomy,and diversity of Internet resources present great challenges to resource sharing in *** DHT overlay (DHT for short) technique has various advantages such as high scalability,low latency,and desirable availability,and is thus an important approach to realizing efficient resource *** construction is a key technique for structured overlays that realizes basic overlay functions including dynamic maintenance and message *** this paper,we first introduce the traditional techniques of DHT topology construction,focusing mainly on dynamic maintenance and message routing of typical DHTs,DHT indexing techniques for complex queries,and DHT grouping techniques for matching domain *** then present recent advances in DHT topology construction techniques in iVCE taking advantage of the characteristics of Internet ***,we discuss the future of DHT topology construction techniques.

关键词： virtual computing environments DHT overlays topology construction distributed indexing flexible routing

More efficient automatic repair of large-scale programs using weak recompilation

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Science china(Information Sciences) 2012年第12期55卷 2785-2799页

作者： QI YuHua 1,MAO XiaoGuang 1,WEN YanJun 1,DAI ZiYing 1 & GU Bin 2 1 school of computer,national university of defense technology,changsha 410073,china 2 Beijing Institute of Control Engineering,Beijing 100190,china 1. school of computer National University of Defense Technology Changsha 410073 China2. Beijing Institute of Control Engineering Beijing 100190 China

Automatically repairing a bug can be a time-consuming process especially for large-scale programs owing to the significant amount of time spent recompiling and reinstalling the patched *** reduce this time overhead and speed up the repair process,in this paper we present a recompilation technique called weak *** weak recompilation,we assume that a program consists of a set of components,and for each candidate patch only the altered components are recompiled to a shared *** original program is then dynamically updated by a function indirection *** advantage of weak recompilation is that redundant recompilation cost can be avoided,and while the reinstallation cost is completely eliminated as the original executable program is not modified at *** maximum applicability of weak recompilation we created WAutoRepair,a scalable system for fixing bugs with high efficiency in large-scale C *** experiments on real bugs in widely used programs show that our repair system significantly outperforms Genprog,a wellknown approach to automatic program *** the wireshark program containing over 2 million lines of code,WAutoRepair is over 128 times faster in terms of recompilation cost than Genprog.

关键词： weak recompilation efficiency automated program repair automated debugging experiment

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数据网格环境中数据传输服务的研究与实现

计算机应用研究 2004年第10期21卷 212-214页

作者：黄斌彭小宁肖侬刘波怀化学院计算机系湖南怀化418008 国防科学技术大学计算机学院湖南长沙410073

通过对GridFTP作部分修改,实现了独立于Globus环境的、高性能、可靠的数据网格中的数据传输服务,它具有支持基础的安全机制、并行传输、三方传输等功能。剖析了GridFTP,详细介绍了基于GridFTP数据网格环境中的数据传输服务实例。

关键词：数据网格:数据传输 GridFTP 三方传输并行传输

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分布交互仿真系统可扩缩性模型研究

系统仿真学报 2001年第3期13卷 315-318页

作者：史扬凌云翔金士尧黄文斌陆铭华海军潜艇学院软件中心青岛266071 国防科技大学计算机学院PDL国家重点实验室长沙410073

随着分布交互仿真规模及复杂度不断地增加，系统可扩缩性是其面临的主要问题之一,影响系统可扩缩性的主要因素是系统资源受限，采用相应的技术手段可以提高系统的可扩缩性，本文深入研究了系统可扩缩性问题产生的根源，在此基础上提出... 详细信息

随着分布交互仿真规模及复杂度不断地增加，系统可扩缩性是其面临的主要问题之一,影响系统可扩缩性的主要因素是系统资源受限，采用相应的技术手段可以提高系统的可扩缩性，本文深入研究了系统可扩缩性问题产生的根源，在此基础上提出了一个可扩缩性的数学模型，定性及定量地分析比较了当前各种技术措施的优缺点及效能，该模型对于指导仿真系统的设计具有重要的指导意义。

关键词：可扩缩性数据过滤分布交互仿真系统数学模型

虚拟现实技术在鼻腔镜手术仿真训练系统中的应用研究

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系统仿真学报 2001年第S2期13卷 347-349页

作者：谭珂郭光友王大君王勇军吴鹏解放军总医院教育技术中心北京100853 国防科技大学计算机学院湖南410073

讨论了虚拟现实技术在鼻腔镜手术仿真训练中的应用,结合研制开发的具体实用系统,对系统设计、三维重建、实时力反馈、交互漫游、仿真操作等相关技术进行探讨。为把虚拟现实技术拓展到其他医学手术仿真领域提供了技术依据。

关键词：虚拟现实手术仿真三维重建力反馈

QoS-awared replica placement techniques in data grid applications

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Science china(Information Sciences) 2010年第8期53卷 1487-1496页

作者： XIAO Nong, FU Wei & LU XiCheng school of computer, national university of defense technology, changsha 410073, china 1. school of computer National University of Defense Technology Changsha 410073 China

Quality of service is one of the most important factors for successful grid applications. However, individual QoS constraint (IQC) and QoS-awared replica placement have not yet been well addressed in the existing data grid. Existing QoS-awared replica placement algorithms neither can support multiple QoS attributes, nor have good scalability. In this paper, a three-phrase QoS-awared replica placement algorithm based on matrix, namely TP-GABMAC, is presented to solve these problems. Furthermore, a replica ring mechanism is introduced to maintain replica consistency and manage update conflicting. Experiments and analysis demonstrate that the proposed algorithms are not only stable and scalable, but also work well under different network topologies, access patterns and workloads.

关键词： grid data grid QoS-awared replica placement replica ring

Opitimization of tunneling carbon nanotube-FETs based on stair-case doping strategy

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Science china(Information Sciences) 2010年第12期53卷 2696-2704页

作者： ZHOU HaiLiang ,JIANG Jiang,ZHANG MinXuan & FANG Liang school of computer,national university of defense technology,changsha 410073,china 1. school of computer National University of Defense Technology Changsha 410073 China

Due to the fact that either holes or electrons can band-to-band-tunnel(BTBT) through channelsource/drain contacts,tunneling carbon nanotube field effect transistors(T-CNFETs) suffer from ambipolar transporting *** suppress such ambipolar conductance,a novel device design based on stair-case doping strategy of drain region is proposed first in this *** dependences of available ON-OFF current ratio,practical ON-OFF current ratio with certain gate bias range and the average sub-threshold swing on the doping level of drain region are *** results show that such device design can not only increase the ON-OFF current ratio largely but also result in a clear decrease of sub-threshold *** the same time,however,such stair-case doping strategy would broaden the depletion region and result in an increase of device area *** attention should be paid to the choice of doping level of drain region to make a proper tradeoff between power,speed and area in application.

关键词： tunneling carbon nanotube-FETs ambipolar conductance band-to-band-tunneling stair-case doping

Parallel Algorithm in Surface Wave Waveform Inversion

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Wuhan university Journal of Natural Sciences 2001年第Z1期6卷 574-578页

作者： Cao Xiao lin, Song Jun qiang school of computer Science, national university of defense technology, changsha 410073, china school of computer Science National University of Defense Technology Changsha China

In Surface wave waveform inversion, we want to reconstruct 3D shear wave velocity structure, which calculation beyond the capability of the powerful present day personal computer or even workstation. So we designed a high paralleled algorithm and carried out the inversion on Parallel computer based on the partitioned waveform inversion (PWI). It partitions the large scale optimization problem into a number of independent small scale problems and reduces the computational effort by several orders of magnitude. We adopted surface waveform inversion with a equal block(2 o×2 o) discretization.

关键词： surface wave waveform inversion parallel algorithm partitioned waveform inversion