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101.
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
102.
103.
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
104.
105.
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
106.
《Behaviour & Information Technology》2012,31(6):469-477
This paper describes the development of multi-item scales for measuring user perceptions of the ease-of-use and usefulness of the Web (hereafter web), incorporating a system task focus into the scales dimensional structure (e.g. how easy or useful the web is for information search, communication and or purchasing). The items are tested on 2077 web users recruited using a web survey, revealing four factors for each scale. Perceived ease-of-web use consists of learning, search and find, transaction and communication ease, and perceived web usefulness consists of communication, purchase, information search and acquisition, and access to quality products and information. A regression analysis on web usage frequency shows how easy users find it to learn how to use the web and how useful the web is for purchasing are the best predictors of how frequently they will use the web. These results highlight the importance of training users how to effectively use hypermedia-based systems like the web, and the design of systems that are easy to navigate and that provide advanced functionality for transactional activity. 相似文献
107.
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
108.
为拓宽开关电源产品的电压范围,提出了1种基于恒流驱动模式的能在10~80V宽电压范围工作的串联型开关稳压电源.该开关电源采用恒流方式驱动开关管,开关管在宽电压范围内始终能够得到理想的驱动电流.实验表明,该开关电源效率高、工作稳定、成本低,因此,可使用于工业用各种报警器产品和爆闪式信号灯中. 相似文献
109.
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
110.
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