基于微分对策的多飞行器协同捕获空间划分

针对多飞行器协同围捕问题,提出一种基于微分对策的加权制导律下捕获空间划分方法。选取合适的性能函数,建立多对一协同围捕微分对策模型;利用哈密尔顿函数法求解得出飞行器和目标的最优控制策略,获得各飞行器的零控脱靶量的最优轨迹;以2个飞行器为例,设置1个2对1协同围捕场景,根据2个飞行器初始零控脱靶量的符号和大小关系,给出各飞行器单独拦截以及协同围捕状态下的相关定义;根据各飞行器零控脱靶量的最优轨迹,围绕初始零控脱靶量给出1种协同捕获空间的划分方法;设置3个具体的仿真场景,验证结果证明了该方法的准确性。     

Walkability vs. walking: assessing outcomes of walkability at Southeast False Creek,Vancouver, Canada

ABSTRACT

If a neighbourhood is designed and built according to best practices for walkable neighbourhood design, will people respond and walk in the public realm? This was a narrowly focused case study of a brownfield redevelopment in Vancouver, Canada, intentionally designed to be highly walkable. Methods included a Walk Score® analysis, both in-person and video observational studies of people using three public spaces over a nine-month period, supplemented with questionnaires. Observational studies and questionnaires revealed high numbers of people using the public spaces for walking and active mobility throughout the year in all weather conditions, validating a very high Walk Score®. However, the study also uncovered unexpected patterns of walking and motivations for walking, which reveals the value of post-occupancy observational and survey studies to fully understand how specific attributes of the neighbourhood landscape may significantly change what people value and how they use the public realm.     

直升机分布式自动飞行仿真平台设计与实现

针对直升机飞控平台结构混乱的问题,基于VS和Qt开发平台,提出并建立了分布式交互飞行仿真系统和软件环境。建立了直升机非线性模型并完成飞控系统设计,验证其准确性;完成飞管系统各模块的研究和设计,实现直升机全自动飞行。仿真结果表明:所设计的分布式自动飞行仿真平台结构清晰,各模块分工明确,可优化直升机各项工作,确保直升机平台协调运行。     

Non‐cooperative game‐based packet ferry forwarding for sparse mobile wireless networks

In sparse mobile wireless networks, normally, the mobile nodes are carried by people, and the moving activity of nodes always happens in a specific area, which corresponds to some specific community. Between the isolated communities, there is no stable communication link. Therefore, it is difficult to ensure the effective packet transmission among communities, which leads to the higher packet delivery delay and lower successful delivery ratio. Recently, an additional ferry node was introduced to forward packets between the isolated communities. However, most of the existing algorithms are working on how to control the trajectory of only one ferry work in the network. In this paper, we consider multiple ferries working in the network scenario and put our main focus on the optimal packet selection strategy, under the condition of mutual influence between the ferries and the buffer limitation. We introduce a non‐cooperative Bayesian game to achieve the optimal packet selection strategy. By maximizing the individual income of a ferry, we optimize the network performance on packet delivery delay and successful delivery ratio. Simulation results show that our proposed packet selection strategy improves the network performance on packet delivery delay and successful delivery ratio. Copyright © 2013 John Wiley & Sons, Ltd.     

Selection of government supervision mode of PPP projects during the operation stage

During the operation stage of public-private partnership (PPP) projects, investors may engage in opportunistic behaviour in pursuit of their own profits. In order to curb this kind of behaviour, this article analyses the selection of government supervision mode based on evolutionary game theory taking the perspective of government supervision. The results show that government supervision mode is closely related to the probability of identifying investors’ speculative behaviour through outcome-oriented supervision. When the probability of identifying such behaviour is relatively high, the equilibrium strategy of investors and governmental supervision institutions is (not to behave opportunistically, outcome-oriented supervision). In contrast, if the probability is relatively low, there is no set of evolutionarily stable strategies (ESS); rather, a periodic behavioural pattern is formed. In this scenario, the strategies ultimately chosen by both sides relate to initial states and the payoffs of the options. Furthermore, determinants and some recommendations for government supervision are proposed, providing a reference for efficient governance.     

Managing project changes: Case studies on stage iteration and functional interaction

This paper investigates project changes and their relationships with stage iteration and multi-functional interaction. Changes often occur in a complex solution-based project, which makes the linear management model limited in its application. Complex project planning is based on assumptions about future events. Assumptions often fail and as a result the plans contain activities that are impossible or unnecessary to execute. The consistency of project planning needs to be restored and maintained by revising or redefining project activities.     

软黏土中双排微型桩围护结构的开挖过程性能分析

双排微型桩围护结构兼具施工便利和侧向刚度高的优点。为获知其原位工作性能,在软黏土场地内施工88根微型桩构成双排桩围护结构,通过测斜管、土压力盒、钢筋应力计等量测单元测定挖土过程中的围护结构工作性状。试验结果结合数值分析后发现,随着开挖深度的增加,桩身最大位移不断增大,且最大位移处位于开挖面附近。桩顶能够承受一定的弯矩且弯矩值大小与开挖深度相关,同时桩身弯矩的分布与开挖深度有关。后排桩所受土压力可以通过冠梁和桩间土传递到前排桩上,随着开挖深度的增加,桩间土压力在开挖面上部呈减小趋势,在基坑底以下呈增大趋势,其实测值介于体积比例系数法和弹性地基梁法计算值之间。后排桩所受主动土压力、基坑底部所受被动土压力和桩身位移有关,被动区的实测土压力和弹性地基梁法计算值比较接近。     

软土地基上高层隔震结构模型振动台试验研究

通过对高层隔震结构模型在刚性地基和软土地基条件下进行对比振动台试验,研究软土地基上高层隔震结构的地震反应特性和隔震效果。采用叠层剪切型土箱以减小边界影响,采用粉质黏土作为模型土,考虑基底压力的相似,采用高宽比为4的5层钢框架作为上部隔震结构模型,设计了软土地基上高层隔震结构、非隔震结构以及刚性地基上隔震、非隔震结构的振动台试验模型。试验结果表明：土-结构相互作用（SSI）效应对隔震结构的影响程度较非隔震结构轻;SSI效应显著降低了隔震结构模型的自振频率、增加了体系的阻尼;软土地基上隔震结构能够有效减轻结构的地震反应,但是相对于非隔震结构的加速度反应比值增大,隔震效果降低;SSI效应可能增加也可能减小隔震结构的地震反应,不仅与地震动类型有关还与输入地震动强度相关;软土地基上高层隔震结构基础输入地震动与自由场地震动在反应谱水平上基本一致,采用自由场地震动确定基础输入地震动是可行的,且偏于安全,而非隔震结构基础输入地震动则与地基更深层的地震动接近。     

梁板式基础与地基共同作用数值分析

以某3MW风力发电塔为例,运用ANSYS有限元分析软件建立梁板式预应力锚栓基础与地基的整体有限元模型,进行基础与地基共同作用分析。并以地基弹性模量为参数进行对比分析,得出:随地基弹性模量增大,基底反力向背风侧的底板内边缘集中,基底和塔筒底部不均匀沉降值减少,基础梁的主要受力钢筋最大拉应力也有所减少。     

Structural effects of concrete lining for concrete-lined corrugated steel pipes

This article presents the results of an analytical study on the structural behaviour of buried concrete-lined corrugated steel pipe (CLCSP). CLCSP combines the hydraulic characteristics of concrete pipe with an extended service life compared to unlined corrugated pipe. It is typically factory manufactured and shipped to the jobsite for roadway drainage applications. However, recent investigations have also demonstrated the ability to rehabilitate deteriorating metal culverts using a spray-on mortar lining approach. Since the primary intent of the concrete liner of manufactured CLCSP is to prevent abrasion and corrosion and improve the hydraulic performance, design guides for metal culverts lined with concrete have not been developed. A better understanding of the structural significance and the effect of the concrete lining on the strength of CLCSP is therefore needed. This study evaluated the structural effects of the concrete lining in CLCSP using finite element analysis and detailed soil modelling and proposes a design methodology for CLCSP.