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991.
针对目前三维地矿非均匀场建模难点,基于"三维矢量边界框架下表达体内非均属性数据场的体函数模型",设计开发三维地矿建模系统,该系统在体剖分的基础上,进行三维地矿非均匀场的建模。最后,载入东欢坨矿三维地质数据,建立东欢坨三维地质建模系统,用于矿山资源评价和开采研究。 相似文献
992.
针对无线传感器网络(WSN)中基于环的节点非均匀分布网络模型下的能量空洞问题,提出了一种基于环的节点非均匀分布分簇算法(RCANND)。该算法在节点非均匀分布的网络模型下,通过每环的能耗最小化,计算每一环的最优簇首数;通过节点剩余能量、距基站距离以及与邻居节点的平均距离计算簇首选择度。在簇内以簇首选择度序列表进行簇首轮转,降低分簇次数,提高网络能量的利用效率。对提出的算法进行仿真对比实验,仿真结果表明,相同半径、不同分布模型下节点的平均能耗波动很小;相同分布模型、不同半径下节点的平均能耗波动也不明显。以网络中50%节点存活作为网络生命周期,在节点非均匀分布情况下,所提算法的网络生命周期比混合能量高效分布式不等分簇算法(UHEED)和轮转的混合能量高效分布式不等分簇算法(RUHEED)分别提高约18.1%和11.5%;在节点均匀分布模型下,所提算法的网络生命周期比基于分环的能量高效无线传感器网络分簇路由(RECR)协议提高约6.4%。所提算法有效均衡了不同分布模型下的能耗,有效延长了网络生命周期。 相似文献
993.
分析非均匀填充圆柱介质谐振器的二阶精度FDTD公式 总被引:1,自引:1,他引:0
从积分形式的Maxwell方程出发,利用连续函数的Taylor级数展开,严格地给出了包含介质交界面的二阶精度时域有限差分(FDTD)公式,解决了以往FDTD法处理非均匀介质填充区域问题时只有一阶精度的问题。分析表明,为了获得二阶精度,除了需要引入适当等效介电常数外,还必须采用适当非均匀网格。该方法被用于轴对称圆柱介质谐振器的分析。计算结果与理论值吻合良好,计算精度比传统的FDTD方法提高了一个数量级以上。 相似文献
994.
基础是房屋的重要组成部分之一。基础设计是否合理直接影响房屋的正常使用。本文通过工程实例阐述了在不均匀地基上进行基础设计需要考虑的问题和一般设计方法。 相似文献
995.
Efficient Topology Control for Ad-Hoc Wireless Networks with Non-Uniform Transmission Ranges 总被引:1,自引:0,他引:1
Wireless network topology control has drawn considerable attention recently. Priori arts assumed that the wireless ad hoc networks are modeled by unit disk graphs (UDG), i.e., two mobile hosts can communicate as long as their Euclidean distance is no more than a threshold. However, practically, the networks are never so perfect as unit disk graphs: the transmission ranges may vary due to various reasons such as the device differences, the network control necessity, and the perturbation of the transmission ranges even the transmission ranges are set as the same originally. Thus, we assume that each mobile host has its own transmission range. The networks are modeled by mutual inclusion graphs (MG), where two nodes are connected iff they are within the transmission range of each other. Previously, no method is known for topology control when the networks are modeled as mutual inclusion graphs.The paper proposes the first distributed mechanism to build a sparse power efficient network topology for ad hoc wireless networks with non-uniform transmission ranges. We first extend the Yao structure to build a spanner with a constant length and power stretch factor for mutual inclusion graph. We then propose two efficient localized algorithms to construct connected sparse network topologies. The first structure, called extended Yao-Yao, has node degree at most O(log ), where = maxu maxuvMG
. The second structure, called extended Yao and Sink, has node degree bounded by O(log ), and is a length and power spanner. The methods are based on a novel partition strategy of the space surrounded each mobile host. Both algorithms have communication cost O(n) under a local broadcasting communication model, where each message has O(log n) bits.Xiang-Yang Li has been an Assistant Professor of Computer Science at the Illinois Institute of Technology since 2000. He received MS (2000) and PhD (2001) degree at Department of Computer Science from University of Illinois at Urbana-Champaign. He received his Bachelor degree at Department of Computer Science and Bachelor degree at Department of Business Management from Tsinghua University, P.R. China in 1995. His research interests span the computational geometry, wireless ad hoc networks, game theory, cryptography and network security. Recently, he focuses on performing research on the cooperation, energy efficiency, and distributed algorithms for wireless ad hoc and sensor networks. He served various positions at a number of international conferences. He recently co-organized a special issue of ACM MONET on non-cooperative computing in wireless networks. He is a member of the ACM, IEEE.Wen-Zhan Song received the B.S. degree and M.Eng. degree in computer science from Nanjing University of Science and Technology, Nanjing, in 1997 and 2000. He joined the Department of Computer Science, Illinois Institute of Technology as a Ph.D candidate in 2001. His research interests include wireless networks, and Peer-to-Peer systems.Yu Wang received the PhD degree in computer science from Illinois Institute of Technology in 2004, the BEng degree and the MEng degree in computer science from Tsinghua University, China, in 1998 and 2000. He has been an assistant professor of computer science at the Univeristy of North Carolina at Charlotte since 2004. His current research interests include wireless networks, mobile computing, algorithm design, and artificial intelligence. He is a member of the ACM, IEEE, and IEEE Communication Society. 相似文献
996.
997.
本文以非均匀Catmull-Clark细分模式下的轮廓删除法为基础,通过在细分网格中定义模板并调整细分网格的顶点位置,为非均匀B样条曲面顶点及法向插值给出了一个有效的方法.该细分网格由待插顶点形成的网格细分少数几次而获得.细分网格的顶点被分为模板内的顶点和自由顶点.各个模板内的顶点通过构造优化模型并求解进行调整,自由顶点用能量优化法确定.这一方法不仅避免了求解线性方程组得到控制顶点的过程,而且在调整顶点的同时也兼顾了曲面的光顺性. 相似文献
998.
采用磁控溅射制备了NiFe各向异性磁电阻(AMR)薄膜,经过光学曝光及离子刻蚀将NiFe薄膜制成了宽度w=20μm、厚度t=20nm、长度l=2.5mm的AMR元件.测量了NiFe元件的磁电阻效应.考虑沿宽度方向退磁场的非均匀性,计算了磁电阻比率.结果表明,理论和实验符合. 相似文献
999.
1000.
1INTRODUCTIONHeterogeneous photocatalysis attracts muchattention as a friendly environment technique valu-able for water and air purification.However,thereare some problems in application,and one of thekey problems is the low photon-quantum efficien-cy.From1990s,the modification of Ti O2by metalions has become a hot topic,andthe effect of metal(such as Cu,Fe,Ag,Au,Pt,W,V,Pb,Cr,Rh,Co and Ni)ions doping on photocatalytic ac-tivity of Ti O2has been studied widely[14].Howev-er,there wer… 相似文献