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991.
Alireza Montazeri Behzad Akbari Mohammed Ghanbari 《Peer-to-Peer Networking and Applications》2012,5(3):257-278
P2P video streaming networks are found as a scalable solution and an alternative for traditional client–server based video
streaming over the Internet. One of the significant issues affecting the success of any P2P streaming network is cooperation
between peers. Practical observations have proved the prevalence of free riders in P2P networks that degrade their performance.
To solve this problem, using incentive mechanisms, which encourage peers to contribute more in the network, is necessary.
In this paper, we designed and proposed a distributed and scalable incentive mechanism for mesh based P2P video streaming
networks. In the proposed approach the contribution of the peers is measured and maintained in a distributed fashion. Furthermore,
we proposed an incentive sending side scheduler in which peers are served based on their contribution in the network. Our
simulation evaluations show the efficiency of the proposed approach in improving the overall perceived video quality by the
non-free rider nodes and consequently in the whole network. 相似文献
992.
Mohammed Hawa Jamal S. Rahhal Dia I. Abu-Al-Nadi 《Peer-to-Peer Networking and Applications》2012,5(3):279-291
Peer-to-Peer (P2P) traffic has increased rapidly over the past few years, with file sharing providing the main drive behind
such traffic. In this work we perform a measurement study of the content shared over the popular BitTorrent P2P file sharing
network. We mathematically model the file size distributions of shared files after categorizing them into Audio, Video, Archive
and CD image classes. For each of these categories we look into the most popular shared file formats and investigate their
file size statistics. This provides an important milestone to building a realistic simulation framework for P2P systems, and
for future analytical modeling of P2P networks. 相似文献
993.
D. Cenk Erdil 《Peer-to-Peer Networking and Applications》2012,5(3):219-230
Resource scheduling in large-scale distributed systems, such as grids and clouds, is difficult due to the size, dynamism,
and volatility of resources. These resources are eclectic and autonomous, and may exhibit different usage policies, levels
of participation, capabilities, local load, and reliability. Moreover, applications are likely to exhibit various patterns
and levels, and distributed resources may organize into various different overlay topologies for information and query dissemination.
Researchers have proposed a wide variety of approaches and policies for mapping offered load onto resources and for solving
the various component parts of the scheduling problem. However, production clouds and grids may be underutilized, and may
not exhibit the load to effectively characterize all of the scheduling system inputs. The composition of large-scale systems
is also changing, potentially to include more individual and peer-to-peer resources. These factors will influence the effectiveness
of proposed scheduling solutions. Therefore, a simulation environment is necessary to study different approaches under different
scenarios, especially those that are expected, but that are not currently characteristic of existing systems. This article
describes a general-purpose peer-to-peer simulation environment that allows a wide variety of parameters, protocols, strategies
and policies to be varied and studied. To provide a proof of concept, utilization of the simulation environment is presented
in a large-scale distributed system problem that includes a core model and related mechanisms. In particular, this article
presents a definition and possible peer-to-peer solutions for the large-scale scheduling problem. Moreover, this article describes
a general simulation model, some policies that can be varied, an implementation, and some sample results. 相似文献
994.
为了兼顾模拟集成电路设计优化的求解精度和计算效率,提出一种基于正项式模型修正技术的几何规划优化方法.首先将模拟集成电路的设计目标与约束简化为正项式模型,然后在采用几何规划方法迭代优化的过程中利用晶体管级SPICE仿真不断修正这一正项式模型.实例表明,与传统基于公式的优化方法和基于仿真的优化方法相比,该方法能够在尽量保证计算效率和全局最优解的前提下使优化精度满足晶体管级SPICE仿真的要求. 相似文献
995.
电压信号的非线性问题和多输入跳变现象给时序分析带来了严重挑战.为更好地解决此问题,文中设计电路对门单元输入端和内部节点间的密勒电容进行了验证,从器件结构上分析了其来源,并通过引入该电容改进了已有多输入跳变电流源模型,以获得更高的模型精度;同时将二输入门单元模型扩展到多输入门单元,并详述了建模方法.多种门单元上的数值实验结果表明,与已有模型相比,在可接受的时间开销内,文中模型能够显著地提高门单元时延和输出波形的仿真精度. 相似文献
996.
997.
针对传统分步式结构优化设计的不足,提出一种同时进行结构拓扑、形状和尺寸统一优化的设计方法.首先采用水平集函数描述统一的结构优化模型和几何尺寸边界,通过引入紧支径向插值基函数将结构拓扑优化变量、形状优化变量和尺寸优化变量变换为基函数的扩展系数;然后取该扩展系数为设计变量,借助一种参数的变化表达3种优化要素对结构性能的影响,将复杂的多变量优化问题变换为相对简单的参数优化问题,有利于与相对成熟的优化算法相结合提高求解效率;进一步用R函数将其融合为一个整体,构造出统一优化模型,并用最优化准则法进行求解.最后通过数值案例证明了该方法的有效性和精确性. 相似文献
998.
针对移动无线传感器网络设计一种不依赖于节点地理位置的基于移动汇聚节点(Sink)的数据收集算法(Mobile Sink-based Data Gathering,MSDG)。该算法解决了无线传感器网络中多跳路由通信时出现能量空洞的"热点"问题。Sink沿途以最近的固定节点作为根节点动态构建路由树。簇内移动节点感知的数据经簇头进行数据融合计算,然后将融合后的数据沿路由树反向逐跳转发给Sink。仿真结果表明,MSDG在节点的平均能耗和网络生存时间等方面的性能远超过LEACH、ACE-L等数据收集协议。 相似文献
999.
1000.
本文综述多机器人协作定位的研究现状,分析比较当前该领域的主要研究方向,介绍实现机器人协作定位的主要研究方法和关键技术,并总结多机器人协作定位面临的挑战和发展趋势. 相似文献