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51.
52.
1.引言如何分析、评价并行程序的性能是并行计算的一个重要研究问题。RAM模型为串行算法分析提供了理论基础。据此,我们可以用big-O模型来分析其算法的复杂性。但是,在并行环境下,由于处理机之间增加了通信,使得并行程序及算法分析问题更加复杂。如何在并行程序和计算机结构之间建立一种联系?许多人 相似文献
53.
本文讨论了一种基于网络报文对的网络瓶颈带宽测度技术的原理及实现时一些问题的解决方案,给出了各种典型网络环境下的测试结果,并分析了这种测试方法的潜在误差。 相似文献
54.
In this paper we report new results of our continuous effort on analyzing the impact of incentive mechanisms on user behavior
in BitTorrent. In this second measurement and analysis study we find that free riders’ population has significantly increased
comparing to our previous measurement study. We relate this increase to the advance in end-users’ connection speeds and to
users’ increased knowledge in BitTorrent. We also categorize free riders based on the behavior they exhibit in multiple-torrent
system into three types: cheaters, strategic and lucky peers. Furthermore, refuting the findings of other studies, we show
that peers who exploit the system in BitTorrent are both high bandwidth capacity peers and low bandwidth capacity peers. Moreover,
we argue that the Tit-for-Tat mechanism does not discriminate peers based on their bandwidth capacities and that it reacts
successfully against inter-class bandwidth capacity strategic peers. Finally, we propose a memory-backoff approach to the
optimistic unchoke policy that reduces the volume of free riding in BitTorrent.
Manaf Zghaibeh is a PhD candidate at Stevens Institute of Technology, focusing on P2P economics. He holds a Master’s Degree in Telecommunications Management from Stevens and a Bachelor’s Degree in Electrical Engineering from Damascus University. He has been a teaching assistant at NYU since 2002. Fotios Harmantzis is an Assistant Professor at the School of Technology Management at Stevens Institute of Technology. He holds a B.Sc. and M.Sc. in Computer Science from the University of Crete, a MSE in Systems Engineering from the University of Pennsylvania, a Finance MBA from Toronto/NYU, and a PhD in Electrical and Computer Engineering from the University of Toronto. Dr. Harmantzis’ research and teaching interests include mathematics of finance and risk, valuations of investments under uncertainty and economics of IT and telecom. His research work has been presented in several scientific conferences and journals. He has professional experience in the US, Canada and Europe, in the financial services, asset management and consulting business. 相似文献
Fotios C. Harmantzis (Corresponding author)Email: |
Manaf Zghaibeh is a PhD candidate at Stevens Institute of Technology, focusing on P2P economics. He holds a Master’s Degree in Telecommunications Management from Stevens and a Bachelor’s Degree in Electrical Engineering from Damascus University. He has been a teaching assistant at NYU since 2002. Fotios Harmantzis is an Assistant Professor at the School of Technology Management at Stevens Institute of Technology. He holds a B.Sc. and M.Sc. in Computer Science from the University of Crete, a MSE in Systems Engineering from the University of Pennsylvania, a Finance MBA from Toronto/NYU, and a PhD in Electrical and Computer Engineering from the University of Toronto. Dr. Harmantzis’ research and teaching interests include mathematics of finance and risk, valuations of investments under uncertainty and economics of IT and telecom. His research work has been presented in several scientific conferences and journals. He has professional experience in the US, Canada and Europe, in the financial services, asset management and consulting business. 相似文献
55.
The problem of minimizing the access time of a requested multimedia (MM) document on a network based environment is addressed. A generalized version of this problem is formulated and retrieval strategies that minimize the access time of the user-requested MM document from a pool of MM servers are proposed. To this end, we design single-installment and multi-installment MM document retrieval strategies, through which the minimization of access time can be carried out. The main idea is to utilize more than one MM server in downloading the requested document. Each server assumes the responsibility of uploading a predetermined portion of the entire document in a particular order. Single- and multi-installment strategies differ in the number of disjoint document pieces each server sends to the client. We first introduce a directed flow graph (DFG) model to represent the retrieval process and generate a set of recursive equations using this DFG. Then, we derive closed-form solutions for the portions of the MM document downloaded from the various servers and the corresponding access time. We present rigorous analysis for these two strategies and show their performance under MPEG-I and MPEG-II video streams playback rates. Their behavior under different network bandwidths is also examined, revealing in-depth information about their expected performance. We also show that in the case of a multi-installment strategy, the access time can be completely controlled by fine tuning the number of installments. Since the number of installments is software tunable, the adaptive nature of the strategies to different channel bandwidths is also demonstrated. Important trade-off studies with respect to the number of servers involved in the retrieval process and the number of installments are presented. In the case of a heterogeneous network employing a single-installment strategy, we prove that the access time is independent of the server sequence used. Illustrative examples are provided for ease of understanding. 相似文献
56.
杨巍 《齐齐哈尔轻工业学院学报》2012,(3):52-53
对基于电子测量带宽500MHz以下数字示波器的视频测试、嵌入式系统、射频测试进行了研究,通过实例着重进行了脉冲频谱分析。 相似文献
57.
Due to the heterogeneity and versatility of emerging services and applications in wireless networks,it has been a great challenge to improve the system performance with both the awareness of service ch... 相似文献
58.
针对现今网络业务流量的自相似特性,选取具备显著自相似特征的分形布朗运动流(FBM)为自相似流量模型,提出一种基于优先权的接纳控制新算法.首先,应用统计网络演算对自相似业务的带宽需求进行了更准确的估计;其次,对业务进行优先级标记,对网络中需要保护的重要业务赋予较高的优先级,进行优先强制接纳.通过仿真验证和数值分析,结果表明新算法能给予需要保护的业务更加稳定的接纳性能. 相似文献
59.
活体细胞图像中细胞与背景对比度低,背景中存在密集分布的颗粒状噪声,要有效分割图像并提取细胞特征,预处理就显得尤为重要。针对这一问题将一种改进的均值偏移滤波算法应用到对活体细胞图像背景去除中,在去除图像背景的同时保留了细胞的形貌,并且探讨了核函数带宽选择对均值偏移滤波算法处理效果的影响。 相似文献
60.
马爱清 《上海电力学院学报》2012,28(4):305-308
采用ANSYS软件对500kV电力变压器高压绕组端部电场进行仿真计算,得到了端部电场和电位分布图,指出了端部电场最大电场强度值及其所在位置.通过改变静电环的曲率半径,减小了绝缘层表面的最大场强值,以优化电场分布并确定500kV变压器主绝缘的结构尺寸,为变压器的设计和改进提供了参考依据. 相似文献