Study of impact energy propagation phenomenon and modal characteristics of an armored vehicle undergoing high velocity impact

A new manufacturing technology is being employed to build a new type of armored vehicle. While thick panels are welded together in the old manufacturing technology, relatively thin panels are welded to a frame structure in the new manufacturing technology. The structural integrity of the new type of armor vehicles can be maintained mainly by the frame structures while the panel thickness is reduced significantly to reduce the total vehicle weight. Since the dynamic characteristics of a frame-panel hybrid structure are different from those of the old type of structure which consists of only thick panels, they should be identified to achieve a good performance of the vehicle. For this purpose, a proper FE model of the hybrid type of structure needs to be developed. In the present study, FE models are proposed to represent the frame-panel hybrid type structure efficiently. The impact energy propagation, the transient response and the modal characteristics are investigated with the FE models. This paper was presented at the 4th Asian Conference on Multibody Dynamics(ACMD2008), Jeju, Korea, August 20–23, 2008. Hong-Hee Yoo received a B.S. and M.S. degree in Mechanical Engineering from Seoul National University in 1980 and 1982. He then went on to receive his Ph.D. degree from Michigan State University in 1989. Dr. Yoo is currently a Professor at the School of Mechanical Engineering at Hanyang University in Seoul, Korea. His research interests are in the area of Flexible body dynamics, vibration.     

Thirty years of Polynomial System Solving,and now?

In this introductory paper to the special issue, I describe first my personal view of the history of Polynomial System Solving during my career. Then I describe the main challenges which are now opened by the availability of efficient zero-dimensional solvers.     

A Moving Grid Framework for Geometric Deformable Models

Geometric deformable models based on the level set method have become very popular in the last decade. To overcome an inherent limitation in accuracy while maintaining computational efficiency, adaptive grid techniques using local grid refinement have been developed for use with these models. This strategy, however, requires a very complex data structure, yields large numbers of contour points, and is inconsistent with the implementation of topology-preserving geometric deformable models (TGDMs). In this paper, we investigate the use of an alternative adaptive grid technique called the moving grid method with geometric deformable models. In addition to the development of a consistent moving grid geometric deformable model framework, our main contributions include the introduction of a new grid nondegeneracy constraint, the design of a new grid adaptation criterion, and the development of novel numerical methods and an efficient implementation scheme. The overall method is simpler to implement than using grid refinement, requiring no large, complex, hierarchical data structures. It also offers an extra benefit of automatically reducing the number of contour vertices in the final results. After presenting the algorithm, we demonstrate its performance using both simulated and real images. This work was supported in part by NSF/ERC Grant CISST#9731748 and by NIH/NINDS Grant R01NS37747.     

基于拓扑统计距离的航迹抗差关联算法

传感器观测目标的拓扑信息可用于解决系统误差下的航迹关联问题,但传统方法对航迹信息利用不足且难以适应传感器虚警和漏报的情形。论文提出一种基于拓扑统计距离的航迹抗差关联算法,首先转换目标状态估计及其协方差以得到目标参照系下的拓扑描述;然后在推导拓扑统计距离的基础上,进行全局最优关联;最后以目标参照系下邻居目标关联对的平均统计距离作为参照目标间的关联度,根据双门限准则完成参照目标的关联判决。仿真结果表明,在密集编队目标、随机分布目标和传感器存在虚警漏报条件下,该算法的性能明显优于传统方法。     

高速数字电路信号完整性问题分析与解决方案

为确保电路板制作前其信号完整性,缩短产品的开发周期,节约设计成本,利用信号完整性仿真工具,通过采用Cadence的PCBSI软件对其布局前的仿真,重点研究了电路拓扑结构问题,并提出相应的解决措施,具有工程应用实际参考价值。     

WSNs中基于能量代价的最小权和支配集拓扑控制算法

该文针对无线传感器网络中最小连通支配集拓扑并非网络耗能最小拓扑的问题,定义由节点剩余能量,邻居个数和通信代价构建的能量代价函数综合反映支配节点的能量效率以及对降低网络整体能耗的贡献,进而以其作为拓扑权值,提出一种基于能量代价的最小权和连通支配集拓扑控制算法。算法选取局部最小权值节点担负支配任务,搭建整体权和最小的支配集,最小化网络整体能耗。实验结果表明,算法不仅具有节能的特点,还确保了通信链路的可靠性,有效延长了网络生命周期。     

大规模服务覆盖网拓扑设计

针对大规模服务覆盖网拓扑设计方法构建效率低的问题,该文提出了以带宽容量为约束条件,基于多商品流的线性规划模型和实现算法,以降低构建算法的时间与空间复杂度。仿真结果表明,该算法在大规模网络情况下,构建效率和资源利用率有显著提高。     

基于物联网的煤矿实时监测的拓扑可靠性设计与优化分析

物联网技术很适合对煤矿进行实时监测,但其可靠性需进一步探究和完善。根据煤矿巷道窄长且干扰因素多等特点,提出了一种适合煤矿安全监测的三维均匀物联网节点部署方法。在保障监测数据准确的基础上,进一步研究了提高物联网拓扑可靠性的相关机制,如节点之间的距离冗余、簇头节点的非等量备份冗余,并对相关的参数进行量化分析。从理论分析和仿真的结果看,所提出的方法具有监测区域覆盖程度高、能耗均衡和灵活可扩展等特点,对提高煤矿安全监测的拓扑可靠性具有显著效果。     

Relay sensor placement in wireless sensor networks

This paper addresses the following relay sensor placement problem: given the set of duty sensors in the plane and the upper bound of the transmission range, compute the minimum number of relay sensors such that the induced topology by all sensors is globally connected. This problem is motivated by practically considering the tradeoff among performance, lifetime, and cost when designing sensor networks. In our study, this problem is modelled by a NP-hard network optimization problem named Steiner Minimum Tree with Minimum number of Steiner Points and bounded edge length (SMT-MSP). In this paper, we propose two approximate algorithms, and conduct detailed performance analysis. The first algorithm has a performance ratio of 3 and the second has a performance ratio of 2.5. Xiuzhen Cheng is an Assistant Professor in the Department of Computer Science at the George Washington University. She received her MS and PhD degrees in Computer Science from the University of Minnesota - Twin Cities in 2000 and 2002, respectively. Her current research interests include Wireless and Mobile Computing, Sensor Networks, Wireless Security, Statistical Pattern Recognition, Approximation Algorithm Design and Analysis, and Computational Medicine. She is an editor for the International Journal on Ad Hoc and Ubiquitous Computing and the International Journal of Sensor Networks. Dr. Cheng is a member of IEEE and ACM. She received the National Science Foundation CAREER Award in 2004. Ding-Zhu Du received his M.S. degree in 1982 from Institute of Applied Mathematics, Chinese Academy of Sciences, and his Ph.D. degree in 1985 from the University of California at Santa Barbara. He worked at Mathematical Sciences Research Institutea, Berkeley in 1985-86, at MIT in 1986-87, and at Princeton University in 1990-91. He was an associate-professor/professor at Department of Computer Science and Engineering, University of Minnesota in 1991-2005, a professor at City University of Hong Kong in 1998-1999, a research professor at Institute of Applied Mathematics, Chinese Academy of Sciences in 1987-2002, and a Program Director at National Science Foundation of USA in 2002-2005. Currently, he is a professor at Department of Computer Science, University of Texas at Dallas and the Dean of Science at Xi’an Jiaotong University. His research interests include design and analysis of algorithms for combinatorial optimization problems in communication networks and bioinformatics. He has published more than 140 journal papers and 10 written books. He is the editor-in-chief of Journal of Combinatorial Optimization and book series on Network Theory and Applications. He is also in editorial boards of more than 15 journals. Lusheng Wang received his PhD degree from McMaster University in 1995. He is an associate professor at City University of Hong Kong. His research interests include networks, algorithms and Bioinformatics. He is a member of IEEE and IEEE Computer Society. Baogang Xu received his PhD degree from Shandong University in 1997. He is a professor at Nanjing Normal University. His research interests include graph theory and algorithms on graphs.     

Angular MST‐Based Topology Control for Multi‐hop Wireless Ad Hoc Networks

This letter presents an angular minimum spanning tree (AMST) algorithm for topology control in multi‐hop wireless ad hoc networks. The AMST algorithm builds up an MST for every angular sector of a given degree around each node to determine optimal transmission power for connecting to its neighbors. We demonstrate that AMST preserves both local and network‐wide connectivity. It also improves robustness to link failure and mitigates transmission power waste.