Connectivity compression of triangle meshes based on geometric parameter predict

An efficient encoding algorithm for lossless compression of triangle mesh connectivity is presented to further optimize the compression ratio. The algorithm firstly cuts a given mesh into a cutaway graph, then uses a triangle nodes tree to present the graph, containing the triangle strips topology information on the graph in the adjacency relationships between the leaf nodes and the branch nodes, reducing the mesh topology information needed to be encoded. Finally, we use the minimum interior angle maximum principle to predict the internal topology of the triangle strips, only encoding the prediction error elements, thus further reducing the information needed to be encoded. Compared with the current compression algorithms, this algorithm does not traverse the triangular mesh, only encoding and storing a small amount of mesh topology information and prediction information. Experimental results show that the algorithm can greatly reduce the compression ratios and process various triangle meshes.     

One-to-one disjoint path covers on multi-dimensional tori

The multi-dimensional torus is one of the most popular underlying topologies for massively parallel systems. In this study, we consider a non-bipartite n-dimensional torus where n≥2 and prove that for 1≤m≤2n, m vertex disjoint paths exist that cover all vertices between any two distinct vertices. In other words, we construct the one-to-one m-disjoint path cover of a non-bipartite torus for any m where 1≤m≤2n.     

基于连通度算子的系统漏洞风险评估

为对安全漏洞的风险进行量化评估,提出一种基于连通度算子的漏洞风险评估方法。通过构建的漏洞攻击图对漏洞的利用关系进行定量分析,并提出两种连通度算子,对漏洞间的连通度进行计算,实现对漏洞自身风险和传播风险的量化分析;在此基础上提出风险评估算法VREA-CO,对系统漏洞的全局风险进行评估,评估结果能够帮助管理者确定关键漏洞,提高安全管理的效率。实例分析结果表明,该方法是可行有效的。     

传感器网络基于动态密钥池的密钥建立方案

针对网络在整个生命周期内的可持续安全性问题,基于动态密钥池技术提出了一个新的对密钥建立方案(KES-D).在此方案中,节点分n次部署,密钥池根据节点部署的次数分代.第i代密钥池由第i-1阶段的密钥池去除m条使用时间最长的二维反向密钥链再加上m条新二维反向密钥链组成.理论分析及模拟结果表明:与适用于多次部署的传感器网络密钥管理方案相比,该方案的抗毁密钥连通率显著提高.     

Connectivity maintenance and distributed tracking for double‐integrator agents with bounded potential functions

In this paper, we develop a set of decentralized control laws with bounded potential functions. The basic control law is a combination of attractive, repulsive, and alignment forces, which can keep connectivity, avoid collision, synchronize all agents, and further track a constant moving leader. Furthermore, we investigate the distributed tracking problem with a varying‐velocity leader, where the acceleration of the leader can not be measured. Two cases are considered; the acceleration of the leader is bounded, and the acceleration function satisfies Lipschitz condition. In the first case, the relative velocities of neighbors are integrated and transmitted as a new variable to account for the uncertain time‐varying acceleration. In the second case, two distributed estimators are added for the leader's position and velocity. Finally, some simulations are presented to show the effectiveness of the proposed algorithms. Copyright © 2013 John Wiley & Sons, Ltd.     

Contention-based forwarding with multi-hop connectivity awareness in vehicular ad-hoc networks

Recent vehicular routing proposals use real-time road traffic density estimates to dynamically select forwarding paths. Estimating the traffic density in vehicular ad hoc networks requires the transmission of additional dedicated messages increasing the communications load. These proposals are generally based on unicast sender-based forwarding schemes. The greedy nature of sender-based forwarding can result in the selection of forwarders with weak radio links that might compromise the end-to-end performance. To overcome these limitations, this paper presents TOPOCBF, a novel contention-based broadcast forwarding protocol that dynamically selects forwarding paths based on their capability to route packets between anchor points. Such capability is estimated by means of a multi-hop connectivity metric. The obtained results demonstrate that TOPOCBF can provide good packet delivery ratios while reducing the communications load compared to unicast sender-based forwarding schemes using road traffic density estimates.     

基于复杂网络理论的无线传感器网络特征度量分析

通过研究复杂网络的理论,介绍了复杂网络的几种主要特征度量,并以此分析了无线传感器网络的特性。列举了无线传感器网络的节点度分布、集聚系数、平均路径长度、网络联通性等特性。研究了节点数、通讯半径、连通率间的关系,由仿真的数据得出,增加节点不能完全保证网络的联通,只能增加联通的概率,而增加通讯半径则可以迅速地使网络联通。因此,在条件允许的情况下,选择通讯半径大的传感器比增加撒布节点更能保证网络的联通。最后给出了适合于无线传感器网络的介数的评价方法。     

无线传感网络中能量均衡的连通支配集算法

连通支配集是无线传感器网络中构建虚拟骨干网络的重要手段.由于支配集中节点的能耗相对其他节点要多,支配集中剩余能量较小的节点决定了虚拟骨干网的生命周期.现有算法或者只是关注构造较小的支配集,或者没有考虑调整能耗极快的支配节点.提出了一种能量均衡的连通支配集算法,基于节点剩余能量和连通度构造支配集,在网络运行过程中根据耗能速度,提前选择候选支配节点,分流负载过重的支配节点.仿真结果表明,新算法能以较小消息开销,有效延长网络寿命.     

On conditional diagnosability and reliability of the BC networks

An n-dimensional bijective connection network (in brief, BC network), denoted by X _n , is an n-regular graph with 2 ⁿ nodes and n2 ^n?1 edges. Hypercubes, crossed cubes, twisted cubes, and Möbius cubes all belong to the class of BC networks (Fan and He in Chin. J. Comput. 26(1):84–90, [2003]). We prove that the super connectivity of X _n is 2n?2 for n≥3 and the conditional diagnosability of X _n is 4n?7 for n≥5. As a corollary of this result, we obtain the super connectivity and conditional diagnosability of the hypercubes, twisted cubes, crossed cubes, and Möbius cubes.     

基于可连Cell的无线传感器网络拓扑控制算法

在无线传感器网络的拓扑控制(TC)中,基于Cell的TC算法被认为是一类可以节省传感器节点能量并延长网络生命周期的方法,但是其需要较多的骨干网节点并且无法保证连通性.通过分析现今算法的内在局限性,提出了一种1-Con思想:当一个Cell的头节点被加入当前骨干网时,所有其可以连接的Cell使用该节点连入拓扑结构,然后此新骨干网递归地继续扩大.基于此思想,设计了一种基于可连Cell的拓扑控制算(CCTC),并从理论上证明:1)CCTC可以保证其所形成的拓扑结构维持网络连通;2)每一轮用于形成骨干网的工作节点非常少.CCTC的计算复杂度是线性的,空间复杂度和信息交换量都是常数量级.仿真实验同样显示,CCTC可以在提供良好鲁棒性和较少的消息交换的情况下,更有效地节省节点能耗并延长网络生命周期.