A fully higher-order compact(HOC)finite difference scheme on the 9-point two-dimensional(2D)stencil is formulated for solving the steady-state laminar mixed convection flow in a lid-driven inclined square enclosure fi...A fully higher-order compact(HOC)finite difference scheme on the 9-point two-dimensional(2D)stencil is formulated for solving the steady-state laminar mixed convection flow in a lid-driven inclined square enclosure filled with water-Al2O3 nanofluid.Two cases are considered depending on the direction of temperature gradient imposed(Case I,top and bottom;Case II,left and right).The developed equations are given in terms of the stream function-vorticity formulation and are nondimensionalized and then solved numerically by a fourth-order accurate compact finite difference method.Unlike other compact solution procedure in literature for this physical configuration,the present method is fully compact and fully higher-order accurate.The fluid flow,heat transfer and heat transport characteristics were illustrated by streamlines,isotherms and averaged Nusselt number.Comparisons with previously published work are performed and found to be in excellent agreement.A parametric study is conducted and a set of graphical results is presented and discussed to elucidate that significant heat transfer enhancement can be obtained due to the presence of nanoparticles and that this is accentuated by inclination of the enclosure at moderate and large Richardson numbers.展开更多
Nodes cooperation is a significant prerequisite for the realization of the relaying Ad Hoc.While with the development of multi-hop cellular networks, how to stimulate intermediate nodes to do the packet-forwarding des...Nodes cooperation is a significant prerequisite for the realization of the relaying Ad Hoc.While with the development of multi-hop cellular networks, how to stimulate intermediate nodes to do the packet-forwarding deserves more concerning.At present research,the incentive schemes in pure Ad Hoc and multi-hop cellular networks are analyzed and compared to classify the strengths and drawbacks of each scheme.We explain in particular what the key issues are to implement incentive schemes for cooperation. Finally,an incentive scheme based on integration of reputation and charging systems is proposed not only to block the existence of selfish nodes,but to satisfy the rational requirement of nodes.展开更多
Ad hoc网络的分簇机制目的是为了利用网络的分级结构来管理众多的移动设备。为了创建和维持一个当节点高速移动时仍然有效的分级结构,必须满足下面的需求:(1)分级结构中每个移动设备能够根据本地信息自动转换它的角色;(2)分级结构的管...Ad hoc网络的分簇机制目的是为了利用网络的分级结构来管理众多的移动设备。为了创建和维持一个当节点高速移动时仍然有效的分级结构,必须满足下面的需求:(1)分级结构中每个移动设备能够根据本地信息自动转换它的角色;(2)分级结构的管理负载要小,每个簇内的节点数目要尽可能地相同。该文提出了一个基于地理定位系统的自适应的多跳分簇机制,试验结果表明新的算法不依赖于节点的移动速度和传播范围,满足上面两个要求。展开更多
Ad Hoc网络现在是非常有吸引力的研究方向,它是一种优秀的移动无线自组织网络,与传统有线网络和一般无线网络存在着很大区别,因而使得传统的基于可信任第三方的CA认证方案不再适用,而基于门限加密的分布方案有其固有的假设条件,在具体...Ad Hoc网络现在是非常有吸引力的研究方向,它是一种优秀的移动无线自组织网络,与传统有线网络和一般无线网络存在着很大区别,因而使得传统的基于可信任第三方的CA认证方案不再适用,而基于门限加密的分布方案有其固有的假设条件,在具体实施时也有很大的困难。有别于以上方案,利用了无证书签名的思想,对无认证中心的基于自认证的门限签名方案在移动Ad Hoc网络环境中的应用进行了研究,并给出了它的实现方案。展开更多
基金supported by the National Natural Science Foundation of China(No.10971159).
文摘A fully higher-order compact(HOC)finite difference scheme on the 9-point two-dimensional(2D)stencil is formulated for solving the steady-state laminar mixed convection flow in a lid-driven inclined square enclosure filled with water-Al2O3 nanofluid.Two cases are considered depending on the direction of temperature gradient imposed(Case I,top and bottom;Case II,left and right).The developed equations are given in terms of the stream function-vorticity formulation and are nondimensionalized and then solved numerically by a fourth-order accurate compact finite difference method.Unlike other compact solution procedure in literature for this physical configuration,the present method is fully compact and fully higher-order accurate.The fluid flow,heat transfer and heat transport characteristics were illustrated by streamlines,isotherms and averaged Nusselt number.Comparisons with previously published work are performed and found to be in excellent agreement.A parametric study is conducted and a set of graphical results is presented and discussed to elucidate that significant heat transfer enhancement can be obtained due to the presence of nanoparticles and that this is accentuated by inclination of the enclosure at moderate and large Richardson numbers.
基金supported by National "863" High Technology Research and Development Program Foundation(No.2006AA01Z208)Six Talented Eminence Foundation of Jiangsu Province+1 种基金Natural Science Foundation of Jiangsu Province(No. BK2004149)Green-Blue Academic Talented Project Foundation of Jiangsu Province
文摘Nodes cooperation is a significant prerequisite for the realization of the relaying Ad Hoc.While with the development of multi-hop cellular networks, how to stimulate intermediate nodes to do the packet-forwarding deserves more concerning.At present research,the incentive schemes in pure Ad Hoc and multi-hop cellular networks are analyzed and compared to classify the strengths and drawbacks of each scheme.We explain in particular what the key issues are to implement incentive schemes for cooperation. Finally,an incentive scheme based on integration of reputation and charging systems is proposed not only to block the existence of selfish nodes,but to satisfy the rational requirement of nodes.
