基于无线紫外光隐秘通信的侦察无人机蜂群分簇算法

针对复杂战场环境下无人机(UAV)蜂群的渗透侦察任务,考虑无人机间信息传输时能量消耗的不均匀性,影响侦察任务的高效实施,该文提出一种基于无线紫外光隐秘通信的侦察UAV蜂群分簇算法。该算法结合无线紫外光散射通信的优点,通过分簇拓扑管理机制对UAV蜂群进行能耗平衡。仿真结果表明,与现有算法相比,所提算法能够有效均衡网络能量消耗,提高网络的传输效率,并且选取合适的数据包长度及节点密度可延长UAV蜂群的生存周期。

     

Efficiency and effectiveness of query processing in cluster-based retrieval

Our research shows that for large databases, without considerable additional storage overhead, cluster-based retrieval (CBR) can compete with the time efficiency and effectiveness of the inverted index-based full search (FS). The proposed CBR method employs a storage structure that blends the cluster membership information into the inverted file posting lists. This approach significantly reduces the cost of similarity calculations for document ranking during query processing and improves efficiency. For example, in terms of in-memory computations, our new approach can reduce query processing time to 39% of FS. The experiments confirm that the approach is scalable and system performance improves with increasing database size. In the experiments, we use the cover coefficient-based clustering methodology (C³M), and the Financial Times database of TREC containing 210 158 documents of size 564 MB defined by 229 748 terms with total of 29 545 234 inverted index elements. This study provides CBR efficiency and effectiveness experiments using the largest corpus in an environment that employs no user interaction or user behavior assumption for clustering.     

Target localization based on energy considerations in distributed sensor networks

Wireless distributed sensor networks are important for a number of strategic applications such as coordinated target detection, surveillance, and localization. Energy is a critical resource in wireless sensor networks and system lifetime needs to be prolonged through the use of energy-conscious sensing strategies during system operation. We propose an energy-aware target detection and localization strategy for cluster-based wireless sensor networks. The proposed method is based on an a posteriori algorithm with a two-step communication protocol between the cluster head and the sensors within the cluster. Based on a limited amount of data received from the sensor nodes, the cluster head executes a localization procedure to determine the subset of sensors that must be queried for detailed target information. This approach reduces both energy consumption and communication bandwidth requirements, and prolongs the lifetime of the wireless sensor network. Simulation results show that a large amount of energy is saved during target localization using this strategy.     

Management and applications of trust in Wireless Sensor Networks: A survey

Wireless Sensors Networks (WSNs) are susceptible to many security threats, and because of communication, computation and delay constraints of WSNs, traditional security mechanisms cannot be used. Trust management models have been recently suggested as an effective security mechanism for WSNs. Considerable research has been done on modeling and managing trust. In this paper, we present a detailed survey on various trust models that are geared towards WSNs. Then, we analyze various applications of trust models. They are malicious attack detection, secure routing, secure data aggregation, secure localization and secure node selection. In addition, we categorize various types of malicious attacks against trust models and analyze whether the existing trust models can resist these attacks or not. Finally, based on all the analysis and comparisons, we list several trust best practices that are essential for developing a robust trust model for WSNs.     

基于移动Agent和WSN的突发事件场景数据收集算法研究

该文针对无线传感器网络应用于突发事件监测场景的能量消耗和网络延迟问题,提出了基于移动Agent的无线传感器网络簇式数据收集算法.动态成簇过程基于事件严重程度,并由其决定簇的生命周期和覆盖范围.Sink和簇头之间形成以Sink节点为簇头的虚拟簇.移动Agent迁移路径规划过程中下一跳节点的选取基于节点剩余能量、路径损耗及受刺激强度.移动Agent通过节点遍历的方式完成对所有簇内成员节点信息的收集.仿真结果表明,相对于C/S数据收集模型,基于移动Agent的模型具有更好的节能效果,并能一定程度地减少网络延迟,尤其适用于大规模无线传感器网络应用.     

A framework using cluster-based hybrid network architecture for collaborative virtual surgery

Research on collaborative virtual environments (CVEs) opens the opportunity for simulating the cooperative work in surgical operations. It is however a challenging task to implement a high performance collaborative surgical simulation system because of the difficulty in maintaining state consistency with minimum network latencies, especially when sophisticated deformable models and haptics are involved. In this paper, an integrated framework using cluster-based hybrid network architecture is proposed to support collaborative virtual surgery. Multicast transmission is employed to transmit updated information among participants in order to reduce network latencies, while system consistency is maintained by an administrative server. Reliable multicast is implemented using distributed message acknowledgment based on cluster cooperation and sliding window technique. The robustness of the framework is guaranteed by the failure detection chain which enables smooth transition when participants join and leave the collaboration, including normal and involuntary leaving. Communication overhead is further reduced by implementing a number of management approaches such as computational policies and collaborative mechanisms. The feasibility of the proposed framework is demonstrated by successfully extending an existing standalone orthopedic surgery trainer into a collaborative simulation system. A series of experiments have been conducted to evaluate the system performance. The results demonstrate that the proposed framework is capable of supporting collaborative surgical simulation.     

无线传感网络量化及能量优化策略

由于无线传感网络(WSN)存在能量和带宽的限制,在网络中直接传送模拟信号受到了极大地制约,因此对模拟信号量化是节省网络能量和保证有效带宽的重要手段.为此,该文以融合中心的重构绝对均值误差最小为原则,设计一种网络量化及能量优化方法.首先,针对单传感器,在能量固定的情况下推导了最优量化位数及在量化位数固定的情况下推导了最优...     

基于聚类的小生境克隆选择算法

基于聚类的小生境克隆选择算法是针对小生境克隆选择算法计算复杂、参数设置困难等缺点而提出的。新算法删除了计算复杂度较大的抑制算子,引入聚类算子,并对算法的部分流程进行了调整。新算法不仅计算复杂度降低,而且无需预知峰的个数等先验知识,仅根据样本数据即可找到全部峰值点。仿真实验验证了C-NCSA的完全收敛性;并且通过与小生境克隆选择算法的对比实验证明：在相同的实验条件下,C-NCSA的执行时间比NCSA明显降低。