移动自组网中节能的组播密钥分发方案

详细分析了地理位置和路由信息对于密钥分发方案的重要性,以及利用K-means算法构造逻辑密钥树的不足,提出一种新的基于路由分支法的节能组播密钥分发方案.实验表明该方案大大减少了组播密钥更新的能耗.     

中国网络广告形式初探

伴随着中国网络广告市场的高速增长,中国网络广告形式也得以不断地进步与提高。文章针对中国网络广告形式进行相应的分析与探讨,旨在发现与提炼中国网络广告形式的变化趋势与凸现问题。     

Kinetic studies of the decom position reaction of adducts of dinuclear Fe( Ⅱ )/O2

Kinetic studies of the decomposition reaction of dinuclear Fe( Ⅱ ) adducts [Fe2(N-Et-HPTB){O2P(OPh)2}](CIO4)2 (1)and [Fe2(N-Et-HPTB) {O2P(Ph)2}] (CIO4)2 (2) with O2 have been carried out at low temperature using UV-vis spectra. The decomposition reaction of Fe( Ⅱ)/O2 adducts was first-order in the experimental conditions, and the activation parameters were obtained. △H￠ = 85.62 kJ @ mol-1, △S≠= 19.43 J @ mol-1 @ K-1 for compound (1) and △H￠ = 97.97 kJ @ mol-1,△S≠ = 55.68 J @ mol-1 @ K-1 for compound (2). These results are similar to those of dioxygen adducts of other metals complexes and natural enzymes such as methane monooxygenase (MMOH).     

A～190区偶偶超变形带转动惯量变化的微观机制

用处理对力的粒子数守恒方法分析了A～ 190区偶偶核系列晕SD带的转动惯量 (动力学转动惯量J(2 ) 与运动学转动惯量J(1) )ω随角频率变化的规律。实验结果在计算中得到较好的重现。粒子数守恒计算中极清楚地展现了J(2 ) 随ω变化的微观机制 (可分别给出各大壳、各推转Nilsson能级上的粒子填布几率和对J(2 ) 的贡献 )。J(2 ) 随ω的变化是壳效应 (变形场中单粒子运动 )、对关联、Pauli堵塞效应以及Coriolis(反配对 )作用等相互竞争的结果。J(2 ) 的上升 ,主要来自高N闯入壳 (中子N =7,质子N =6 )的贡献。     

大跨度岩体隧道工程块体滑落的概率分析

介绍了块体理论,在沈阳至大连高速公路韩家岭隧道工程岩体结构面的观测和调研的基础上,引入概率理论对被节理切割的岩体中关键块进行了分析,推导了概率分析模型,从而使原来的一些关键块体转化为稳定块体,使滑落块体的数量更接近实际工程,并应用于韩家岭隧道工程稳定性分析中·初步结果表明,块体理论适用于像韩家岭大跨度隧道工程等局部围岩稳定性分析问题,大跨度岩体工程的稳定性主要取决于结构面的产状和物理力学性质,以及临空面的几何形态,提出的概率分析理论符合工程实际·     

基于代理重加密的VANETs中安全位置服务

提供车辆位置服务是车载网络(vehicle ad hoc networks, VANETs)的重要应用。而用户(车辆行驶人)希望他的位置信息只能暴露于他授权的消息发送者,这就涉及位置隐私问题。提出基于代理重加密的安全位置服务算法(proxy re-encryption- based secure location service, PRESLS)。PRESLS算法采用中心管理模式,并由交通信息港(traffic information center, TIC)扮演中心管理者,且由TIC维持车辆轨迹数据,同时,TIC作为车辆与路边设施单元的中介,使得路边设施单元能安全地共享轨迹数据。利用代理重加密算法,使得轨迹数据不仅对未授权的实体,而且对TIC也是隐匿的,进而实现了位置数据所保密性。通过安全性能分析和基于地图位置服务(map-based location service, MBLS)的实验评估PRESLS算法的性能。分析表明,车辆能够控制仅由车辆允可的路边设施单元才能接入车辆的轨迹数据。同时,基于MBLS的实验数据表明,PRESLS算法在维持车辆轨迹数据安全的同时,并没有降低位置查询成功率。     

Distributed intrusion detection for mobile ad hoc networks

Mobile ad hoc networking(MANET)has become an exciting and important technology in recent years,because of the rapid proliferation of wireless devices.Mobile ad hoc networks is highly vulnerable to attacks due to the open medium,dynamically changing network topology,cooperative algorithms,and lack of centralized monitoring and management point.The traditional way of protecting networks with firewalls and encryption software is no longer sufficient and effective for those features.A distributed intrusion detection approach based on timed automata is given.A cluster-based detection scheme is presented,where periodically a node is elected as the monitor node for a cluster.These monitor nodes can not only make local intrusion detection decisions,but also cooperatively take part in global intrusion detection.And then the timed automata is constructed by the way of manually abstracting the correct behaviours of the node according to the routing protocol of dynamic source routing(DSR).The monitor nodes can verify the behaviour of every nodes by timed automata,and validly detect real-time attacks without signatures of intrusion or trained data.Compared with the architecture where each node is its own IDS agent,the approach is much more efficient while maintaining the same level of effectiveness.Finally,the intrusion detection method is evaluated through simulation experiments.     

Link reliability based hybrid routing for tactical mobile ad hoc network

Tactical mobile ad hoc network （MANET） is a collection of mobile nodes forming a temporary network, without the aid of pre-established network infrastructure. The routing protocol has a crucial impact on the network performance in battlefields. Link reliability based hybrid routing （LRHR） is proposed, which is a novel hybrid routing protocol, for tactical MANET. Contrary to the traditional single path routing strategy, multiple paths are established between a pair of source-destination nodes. In the hybrid routing strategy, the rate of topological change provides a natural mechanism for switching dynamically between table-driven and on-demand routing. The simulation results indicate that the performances of the protocol in packet delivery ratio, routing overhead, and average end-to-end delay are better than the conventional routing protocol.     

无线Ad Hoc网络中CSCA协议的仿真研究

为了有效利用无线Ad Hoc网络中的信道资源,提出了一种多址接入协议,即信道选择冲突避免(CSCA)协议。该协议在公共信道上发送RTS/CTS分组实现握手,采用灵活的信道选择方案选择无冲突的业务信道传输数据分组,接收节点成功接收完数据分组后在另一个公共信道上回复ACK分组。最后,利用网络仿真工具OPNET构建了CSCA协议的仿真框架,并在此基础上,通过仿真评估了协议的平均信道利用率、平均分组延迟和分组丢弃率等性能。仿真结果表明,CSCA协议在网络传输业务量重的情况下具有较高的信道利用率、较小的分组时延和分组丢弃率。     

基于自适应策略的移动自组网与Internet互联

将Mobile IP与AODV路由协议进行集成以满足移动自组网MANET的Internet访问需求.Mobile IP的FA通过被动接收、解析源节点发送的RREQ-I以了解源节点数量及MANET规模.FA据此将代理通告的TTL作为参数进行自适应调整以实现最佳的代理通告覆盖.由于自适应协议无需额外开销且能根据MANET实际需要改变其提供全局连接信息的主动程度,而其中间节点也可向源节点及时提供自己侦听到的全局连接信息并抑制广播分组的进一步扩散,因此能为网络条件高度动态变化的MANET提供良好的互联性能并保持合理的开销,用NS2进行的仿真结果证明了其有效性.