钢管混凝土组合格构柱高墩偏压试验研究

雅泸高速公路黑石沟特大桥在国内首次提出并采用了钢管混凝土组合格构柱高墩。为研究这种结构形式高墩的组合性能,进行了偏压试验和破坏试验,考察了钢管混凝土柱肢、钢管外包混凝土及腹板剪力墙的受力性能。试验结构表明:正常使用极限状态下,钢管混凝土组合格构柱处于小偏心受压,结构处于弹性状态。     

临时路径发生器学引的UUV跟踪控制(英文)

A path following control algorithm for an unmanned underwater vehicle(UUV) using temporary path generation guidance was proposed in this paper.Owing to different initial states of the vehicle,such as position and orientation,the path following control in the horizontal plane may yield a poor performance.To deal with the negative effect induced by initial states,a temporary path generation was presented based on the relationship between the original reference path and the vehicle’s initial states.With different relative positions between the vehicle and reference path,including out of straight lines,as well as inside and outside a circle,the related temporary paths guiding the vehicle to the reference path were able to be generated in real time.The vehicle was guided to steer along the temporary path until it reached the tangent point at the reference path,where the controller was designed using the input-output feedback linearization method.Simulation results demonstrated that the proposed algorithm is effective under the three different situations mentioned above.     

基于TPA的管路振动贡献量分析

针对工程实际中管路振动贡献量难以定量分析的问题,引入传递路径分析法(TPA)。通过测量各路径的频率响应函数、各安装点和评估点的响应以及估算激励力,进行传递路径分析,进而得到设备与管路各自的贡献量。通过用某型海水泵进行实验,验证了该方法的准确性。实验结果表明,在40～200 Hz频段内,采用该方法得到的响应计算值与测量值误差小于3 dB,满足工程实际要求。     

基于关键链技术在装备维修项目进度管理中的应用研究

根据装备维修工程进度管理的现状,分析传统的关键路径技术(CPM)方法的主要问题,总结计划进度管理方法的优缺点,提出将考虑资源约束的进度管理方法-关键链技术应用于装备维修工程进度管控,运用约束理论和缓冲优化方法对具体工程项目进行进度计划调整与修理工期优化,并通过和CPM方法结果的比较分析,得出关键链技术可以更科学合理制定装备维修项目进度计划并达到优化修期的目的,为装备维修进度管理提供理论与实践参考。     

Dynamic activity-travel assignment in multi-state supernetworks

The integration of activity-based modeling and dynamic traffic assignment for travel demand analysis has recently attracted ever-increasing attention. However, related studies have limitations either on the integration structure or the number of choice facets being captured. This paper proposes a formulation of dynamic activity-travel assignment (DATA) in the framework of multi-state supernetworks, in which any path through a personalized supernetwork represents a particular activity-travel pattern (ATP) at a high level of spatial and temporal detail. DATA is formulated as a discrete-time dynamic user equilibrium (DUE) problem, which is reformulated as an equivalent variational inequality (VI) problem. A generalized dynamic link disutility function is established with the accommodation of different characteristics of the links in the supernetworks. Flow constraints and non-uniqueness of equilibria are also investigated. In the proposed formulation, the choices of departure time, route, mode, activity sequence, activity and parking location are all unified into one time-dependent ATP choice. As a result, the interdependences among all these choice facets can be readily captured. A solution algorithm based on the route-swapping mechanism is adopted to find the user equilibrium. A numerical example with simulated scenarios is provided to demonstrate the advantages of the proposed approach.     

Stability of transportation networks under adaptive routing policies

Growing concerns regarding urban congestion, and the recent explosion of mobile devices able to provide real-time information to traffic users have motivated increasing reliance on real-time route guidance for the online management of traffic networks. However, while the theory of traffic equilibria is very well-known, fewer results exist on the stability of such equilibria, especially in the context of adaptive routing policy. In this work, we consider the problem of characterizing the stability properties of traffic equilibria in the context of online adaptive route choice induced by GPS-based decision making. We first extend the recent framework of “Markovian Traffic Equilibria” (MTE), in which users update their route choice at each intersection of the road network based on traffic conditions, to the case of non-equilibrium conditions, while preserving consistency with known existence and uniqueness results on MTE. We then exhibit sufficient conditions on the network topology and the latency functions for those MTEs to be stable in the sense of Lyapunov for a single destination problem. For various more restricted classes of network topologies motivated by the observed properties of travel patterns in the Singapore network, under certain assumptions we prove local exponential stability of the MTE, and derive analytical results on the sensitivity of the characteristic time of convergence to network and traffic parameters. The results proposed in this work are illustrated and validated on synthetic toy problems as well as on the Singapore road network with real demand and traffic data.     

Application of Lagrangian relaxation approach to α-reliable path finding in stochastic networks with correlated link travel times

This study investigates the important problem of determining a reliable path in a stochastic network with correlated link travel times. First, the distribution of path travel time is quantified by using trip records from GPS probe vehicles. Second, the spatial correlation of link travel time is explicitly considered by using a correlation coefficient matrix, which is incorporated into the α-reliable path problem by Cholesky decomposition. Third, the Lagrangian relaxation based framework is used to handle the α-reliable path problem, by which the intractable problem with a non-linear and non-additive structure can be decomposed into several easy-to-solve problems. Finally, the path-finding performance of this approach is tested on a real-world network. The results show that 15 iterations of calculation can yield a small relative gap between upper and lower bounds of the optimal solution and the average running time is about 5 s for most OD settings. The applicability of α-reliable path finding is validated by a case study.     

大吨位异形钢桥塔施工支架设计研究

为研究不同支架方案对异形钢桥塔施工过程的影响,以新首钢大桥为背景工程做了对比分析,进而分析桥塔施工过程对桥塔-支架整体耦合模型内力、位形的影响,研究支架设计过程中的一些细部问题.结果表明:格构式支架受力明确、合理,施工方便且用钢量小,建议采用该支架方案;桥塔采用反变形的施工方案,可以很好地满足桥梁结构设计线形要求;在格构式支架设计中应避免多个斜撑相贯于立柱同一节点造成支架立柱受力不均匀、部分立柱受力急剧增大的问题;在有限元模拟中支架顶部与高塔连接建议采用铰接方式进行简化处理..     

数控车削加工仿真系统的研究与实现

介绍一个数控车床加工仿真系统,系统实现了对数控代码的词法、语法检验并将代码翻译成动画仿真所需的数据格式．通过在计算机上动画演示加工过程来检验数控代码的正确性．使用该系统可以实现高效率、低成本的培训．     

多目标最短路径模型及算法

为获得满足决策者需要的多目标最短路径问题的有效路径,建立了多目标最短路径模型,并提出了综合k-最短路径算法和多目标格序决策方法的多项式算法.该算法根据决策者可以接受的各单目标的上限,用k-最短路径算法,分别确定各单目标的可行路径集及其交集.再用多目标格序决策方法,比较交集中的有效路径,最终获得决策者满意的路径.