Scheduling for Uncertain Data Broadcast in Mobile Networks

With the increasing popularity of wireless sensor network and GPS (global positioning system) , uncertain data as a new type of data brings a new challenge for the traditional data processing methods. Data broadcast is an effective means for data dissemination in mobile networks. In this paper, the definition of the mean uncertainty ratio of data is presented and a broadcasting scheme is proposed for uncertain data dissemination. Simulation results show that the scheme can reduce the uncertainty of the broadcasted uncertain data effectively at the cost of a minor increase in data access time, in the case of no transmission error and presence of transmission errors. As a result, lower uncertainty of data benefits the qualities of the query results based on the data.     

移动模架法施工连续梁桥线形控制探讨

线形控制是采用移动模架施工连续粱桥的关键技术之一,根据桥面线形控制的原理和方法,结合移动模架法的施工特点,提出了凫洲大桥移动模架法现浇连续箱梁施工的内外模平面线形控制、高程控制、线形监测及调整方案,工程实践表明本文的方案可行。可以为类似工程施工线形控制提供参考。     

高速公路沥青混凝土路面早期裂缝分析

沥青路面各种病害的成因比较复杂,由于环境、地理气候条件的不同,病害情况不一,根据石安高速公路路面病害的调查情况,本文主要分析     

基于移动闭塞的列车自动保护系统的安全设计

以广州旅客自动输送系统（以下简称APM）工程CITYFLO 650TM信号系统为例,分析基于移动闭塞的列车自动保护系统的安全设计。     

Unsupervised spatio-temporal segmentation for extracting moving objects in video sequences

Extraction of moving objects is an important and fundamental research topic for many video ap-plications. This paper addresses an unsupervised spatio-temporal segmentation scheme to extract moving objects from video sequences. The temporal segmentation localizes moving objects by comparing the motion vector of each block in each frame with the corresponding global motion vector estimated by an outlier rejection (OR) based method. Furthermore, the temporal compensation utilizing the temporal coherence of moving objects is considered in the temporal segmentation to solve the temporarily stopping problem. The detected moving regions usually have discontinuous boundaries and some holes. These regions are then compensated in the spatial domain. In the spatial segmentation, the watershed algorithm considering the global information improves the accuracy of segmentation in the spatial domain. The modified mean filter is presented to suppress some minima. By using a fusion module, moving objects are extracted. Experiments on various sequences have successfully demonstrated the validity of the proposed scheme.     

Effects of denial of service attack in mobile ad hoc networks

Mobile ad hoc networks are often deployed in environments where the nodes of the networks are unattended and have little or no physical protection against tampering. The nodes of mobile ad hoc networks are thus susceptible to compromise. The networks are particularly vulnerable to denial of service (DoS) attacks launched through compromised nodes or intruders. In this paper, we investigated the effects of flooding attacks in network simulation 2 (NS-2) and measured the packet delivery ratio and packet delay under different flooding frequencies and different numbers of attack nodes. Simulation results show that with the increase the flooding frequencies and the numbers of attack nodes, network performance drops. But when the frequency of flooding attacks is greater than a value, the performance decrease gets smooth. Meanwhile the packet delay firstly increases and then declines to a value of stability at the end.     

开拓直流移动钢轨焊机市场新征程——访卡特彼勒PRS亚洲区总经理 柳椰子

美国卡特彼勒（Caterpillar）公司成立于1925年,通过不懈努力,其业务已遍及各大洲。卡特彼勒公司始终致力于技术进步及推动积极和可持续的发展。2008年公司销售收入达513亿美元,是世界上最大的建筑和采矿设备、柴油和天然气发动机以及气轮机制造商。同时,该公司还是领先的服务提供商,旗下拥有卡特彼勒融资租赁公司、卡特彼勒再制造服务公司、卡特彼勒物流服务公司以及progressRail铁路服务公司。卡特彼勒公司拥有良好的口碑,连续多年被《财富》杂志评为“全球最受尊敬的公司”之一。作为历史悠久的跨国企业,其产品在铁路行业也得到了广泛的应用。     

箱梁剪力滞效应的横向效应

采用MIDAS软件对箱梁结构进行了梁杆系和板单元的有限元分析比较,通过相同截面的连续梁和悬臂粱,分析了箱梁截面剪力滞效应的横向效应,并得出:箱梁在腹板与顶底板的连接处设置承托十分重要;在设计中考虑有效分布宽度后,仍要注意腹板处的应力峰值.     

20m中小跨径T梁横向分布特点研究

采用空间实体有限元模型,应用刚（铰）接板梁法的思想,分析中小跨径T梁荷载横向分布的规律,并分析原因,考虑有横隔梁对荷载横向分布的影响。     

预应力混凝土T梁防纵裂的保护层厚度计算

讨论了引起混凝土预应力T梁纵向开裂的原因,分析了张紧的预应力钢束对梁体上拱变形的反向作用和受压混凝土由泊松效应引起的横向拉应变作用,并结合理论分析和数值方法提出了考虑上述作用下T梁预应力管道的最小保护层厚度的计算公式。