无线传感器网络中能量有效分簇路由算法

由于无线传感器节点的电源能量有限,提出了一种能量有效分簇路由算法(EECRA).该算法是基于最小能量的数据转发并运用于簇内路由中,簇头由基站根据节点的剩余能量和簇头之间的距离来选定,为了减小簇头节点的能量开销,簇头之间采用了多跳中继的方式将采集的数据发送到基站.仿真结果证明:该算法与LEACH协议相比,不仅提高了网络寿命,同时节点的能耗均衡性、网络扩展性和可靠性都大大的提高.     

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航空运输是国家综合运输系统的重要组成部分,但航空运输网络与综合运输网络在网络特性上区别明显. 与综合运输网络呈现随机网络的特征不同,航空运输网络具有无标度网络的特征,枢纽节点和干线航段的集中度高,网络呈现为轮辐式结构,机场节点是网络中的重要基础设施,也易成为网络效率的瓶颈. 在综合运输大通道上,航空运输方式与其他交通方式的关系表现为在客货运输市场上的自然分工和自由竞争;在综合交通枢纽上则表现为衔接与合作关系. 机场枢纽是体现综合运输效率的关键点,需要其他运输方式的主动衔接与配合,以发挥航空运输高效快速的优势. 基于不同的网络特性,为实现两种运输网络的协同,有必要优化和改善航空运输与综合运输网络的衔接.     

战时配送网络转化研究

战时配送网络是配送活动的载体,始终处于动态变化之中。在对战时配送网络分析的基础上,从简单的网络图人手,分三个步骤逐步生成了单种运输方式的配送网络转化图、多种运输方式的配送网络转化图、有破坏点的配送网络转化图,为配送决策者处理配送网络中的特殊点提供了一种较好的方法。     

无线传感器网络电子航标节点定位算法研究

介绍了无线传感器网络电子航标节点测距定位的定位原理和算法.针对该定位算法的非线性方程组求解问题,依据UKF算法,用一个最小的样本点集来近似系统状态的分布函数.实现了当系统按实际的非线性模型演化时,对非线性函数的后验均值与方差的很好拟合.仿真结果表明,用UKF算法的节点定位估计精度在5%以内.可见,它在解决非线性机动目标跟踪问题时有比较好的跟踪性能和滤波结果.     

某型平台罗经专家故障诊断系统知识库和推理机研究

某型平台罗经是大型复杂精密机械电子设备,为了快速提高维修速度,需建立一套高效适用的专家诊断系统,而专家知识库是系统的关键组成部分。在充分分析平台罗经各种故障类型的基础上,选择采用故障树诊断方法、专家系统方法、神经网络方法相结合,建立了一套高效的故障诊断系统知识库。     

Social networks as a source of private-vehicle transportation: The practice of getting rides and borrowing vehicles among Mexican immigrants in California

We examine the role of social networks in enabling access to private-vehicle transportation, through getting rides and borrowing cars. Based on qualitative findings from ten focus group discussions with recent Mexican immigrants to California, half of whom have no car, we describe the extent to which participants depend on rides and borrowed cars for transportation. We highlight the unique aspects of informal access to cars, drawing on social exchange theory and related research to characterize the procurement process and likely levels of exchange. We discuss the implications of these findings for transportation services that might serve this and other community groups.     

Design and implementation of efficient transit networks: Procedure, case study and validity test

This paper presents and tests a method to design high-performance transit networks. The method produces conceptual plans for geometric idealizations of a particular city that are later adapted to the real conditions. These conceptual plans are generalizations of the hybrid network concept proposed in Daganzo (2010). The best plan for a specific application is chosen via optimization. The objective function is composed of analytic formulae for a concept’s agency cost and user level of service. These formulae include as parameters key demand-side attributes of the city, assumed to be rectangular, and supply-side attributes of the transit technology. They also include as decision variables the system’s line and stop spacings, the degree to which it focuses passenger trips on the city center, and the service headway. These decision variables are sufficient to define an idealized geometric layout of the system and an operating plan. This layout-operating plan is then used as a design target when developing the real, detailed master plan. Ultimately, the latter is simulated to obtain more accurate cost and level of service estimates.This process has been applied to design a high performance bus (HPB) network for Barcelona (Spain). The idealized solution for Barcelona includes 182 km of one-way infrastructure, uses 250 vehicles and costs 42,489 €/h to build and run. These figures only amount to about one third of the agency resources and cost currently used to provide bus service. A detailed design that resembles this target and conforms to the peculiarities of the city is also presented and simulated. The agency cost and user level of service metrics of the simulated system differ from those of the idealized model by less than 10%. Although the designed and simulated HPB systems provide sub-optimal spatial coverage because Barcelona lacks suitable streets, the level of service is good. Simulations suggest that if the proposed system was implemented side-by-side with the current one, it would capture most of the demand.     

基于无线Mesh网络的舰艇编队通信网运用研究

根据未来海战信息网络建设需求,分析了无线Mesh网络的技术特点和网络结构,提出了一种海战场环境下基于Mesh结构的无线网络应用方案,满足舰艇编队通信网络高速率、大容量、非视距传输的要求,对无线Mesh网络在军事通信领域的深入研究具有一定的参考价值。     

一种改进的自组网动态信道分配协议

文章针对节点具有双收发器多信道的自组网,对动态分配协议进行了改进,使得一些短报文可以在没有可用数据信道时直接在控制信道上传输,从而解决信道利用率不高的问题。研究表明,改进后协议的网络吞吐量有了显著的提高。     

海监船与渔政船主尺度模型研究

分析了我国海监船和渔政船发展现状及发展趋势。整理分析相关的船型数据资料,利用逐步回归的数学方法,分别基于Excel回归分析、MATLAB的BP神经网络工具箱和RBF神经网络工具箱,建立了海监船和渔政船主尺度的数学模型,并对3种数学统计模型进行了实船验证和误差分析,结果显示BP神经网络和RBF神经网络模型误差较小。数学模型的建立有利于分析和掌握海监船与渔政船主尺度变化的规律,为报价设计和初步设计提供了科学依据。