遗传算法在区段站到发线的应用研究

为解决车站到发线的合理运用问题，采用遗传算建立了到发线运用的染色体结构和适应度函数，对这种复杂的非线性组合优化问题进行了仿真。     

Wheel-rail contact models for vehicle system dynamics including multi-point contact

Advanced modelling of rail vehicle dynamics requires realistic solutions of contact problems for wheels and rails that are able to describe contact singularities, encountered for wheels and rails. The basic singularities demonstrate themselves as double and multiple contact patches. The solutions of the contact problems have to be known practically in each step of the numerical integration of the differential equations of the model. The existing fast, approximate methods of solution to achieve this goal have been outlined. One way to do this is to replace a multi-point contact by a set of ellipses. The other methods are based on so-called virtual penetration. They allow calculating the non-elliptical, multiple contact patches and creep forces online, during integration of the model. This allows nearly real-time simulations. The methods are valid and applicable for so-called quasi-Hertzian cases, when the contact conditions do not deviate much from the assumptions of the Hertz theory. It is believed that it is worthwhile to use them in other cases too.     

Simulation on progressive collapse behaviour of whole ship model under extreme waves using idealized structural unit method

To ensure the safety of navigating ship, working loads and structural load-carrying capacity are two important aspects. In the present paper, a total simulation system combing load calculation and structural collapse analysis is applied to simulate progressive collapse behaviour of a single-hull Kamsarmax type bulk carrier. A three dimensional singularity distribution method is adopted to calculate pressure distribution with time history. A mixed structural model, collapse part simulated by ISUM elements and remaining part by elastic FEM elements with relative coarse mesh, is proposed for collapse analysis. Progressive collapse behaviour obtained by ISUM is good agreement with that by nonlinear software package, MARC. However, the calculation time of ISUM analysis is about 1/70 of MARC analysis. The applicability to structure system, high accuracy and sufficient efficiency of ISUM had been demonstrated.     

轨道客车不锈钢车体电化学钝化工艺研究

文章通过显微组织、显微硬度、电化学性能表征测试,分析了不锈钢车体焊缝及热影响区的组织变化及性能差异,研究了钝化道次、移动速度等电化学钝化工艺参数对焊接接头及热影响区耐蚀性的影响规律.试验结果表明:焊接热影响区显微组织发生明显改变,显微硬度下降,表面耐蚀性明显下降,当以10 mm/s单道次钝化作业时,点蚀电位最高,耐蚀性最好,30天盐雾试验后,钝化处理表面未发现明显锈蚀.该工艺已在公司进行了推广应用,效果良好.     

R/S分析法在盾构下穿机场过程中的地表变形规律研究

为保证机场的正常运营,在盾构下穿机场的施工过程中,对地表沉降变形控制的要求较高,因此对穿越过程中的施工控制和变形规律研究具有重要意义。首先,基于盾构下穿机场的工程条件,分析盾构下穿过程中的风险,并提出相应的控制措施;同时,根据现场监测数据,分析盾构下穿机场过程中的地表沉降变形规律,并利用R/S分析法对地表沉降的发展趋势进行研究。结果表明:盾构施工引起的机场地表变形均在控制值范围以内,且各监测点在不同序列条件下的Hurst指数均大于0.5,具有沉降持续减弱的趋势,验证下穿过程中风险控制措施的有效性,为类似下穿机场的盾构施工提供一定的实践经验,也为盾构施工引起的地表沉降变形规律研究提供参考。     

Large-scale dynamic transportation network simulation: A space-time-event parallel computing approach

This paper describes a computationally efficient parallel-computing framework for mesoscopic transportation simulation on large-scale networks. By introducing an overall data structure for mesoscopic dynamic transportation simulation, we discuss a set of implementation issues for enabling flexible parallel computing on a multi-core shared memory architecture. First, we embed an event-based simulation logic to implement a simplified kinematic wave model and reduce simulation overhead. Second, we present a space-time-event computing framework to decompose simulation steps to reduce communication overhead in parallel execution and an OpenMP-based space-time-processor implementation method that is used to automate task partition tasks. According to the spatial and temporal attributes, various types of simulation events are mapped to independent logical processes that can concurrently execute their procedures while maintaining good load balance. We propose a synchronous space-parallel simulation strategy to dynamically assign the logical processes to different threads. The proposed method is then applied to simulate large-scale, real-world networks to examine the computational efficiency under different numbers of CPU threads. Numerical experiments demonstrate that the implemented parallel computing algorithm can significantly improve the computational efficiency and it can reach up to a speedup of 10 on a workstation with 32 computing threads.     

行政裁决:地方政府的制度推力

在统计时间内有效的行政裁决制度共有16项,分布在自然资源和环境、知识产权以及民间纠纷三大领域,均为中央政府的法律、行政法规和部门规章所设定.但行政裁决设定的领域范围在逐步退缩,已设定的行政裁决被纷纷废止,新的法律更倾向规定调解或仲裁.行政裁决实施性规定多集中于与土地有关的行政裁决,其中绝大多数系由地方政府所制定.地方政府不仅做出了细密规定,而且纷纷制定了专门性规定.但在矿权、环境、知识产权和民间纠纷领域,地方政府并未充分发挥出细化法律、行政法规和部门规章中行政裁决条款的作用,更没有制定专门的行政裁决规定.有关行政裁决的行政规范性文件高度集中于征地补偿裁决、拆迁补偿裁决和林地权属裁决.其中,林地权属裁决的中央行政规范性文件较多,征地补偿裁决和拆迁补偿裁决的地方行政规范性文件较多.这些行政规范性文件的内容,集中在纠纷的化解而非行政裁决制度本身.从行政裁决引发的诉讼案件反观行政裁决制度,征地补偿裁决、拆迁补偿裁决和林地权属裁决都在运行,其他行政裁决制度都没有运行.其中,拆迁补偿裁决的运行异常活跃,征地补偿裁决的运行却极为低迷.统计发现的耦合是:凡地方政府对行政裁决制定了专门性实施规定的,行政裁决制度都在运行,否则都已停滞；地方行政规范性文件被用作行政裁决依据的多少,与该行政裁决的活跃程度成正比.当然,上述发现的证成或证伪,有待于另一项研究.     

Conflict-free arrival and departure trajectory planning for parallel runway with advanced point-merge system

In this paper, an efficient trajectory planning system is proposed to solve the integration of arrivals and departures on parallel runways with a novel route network system. Our first effort is made in designing an advanced Point Merge (PM) route network named Multi-Level Point Merge (ML-PM) to meet the requirements of parallel runway operations. Then, more efforts are paid on finding a complete and efficient framework capable of dynamically modelling the integration of arrival and departure trajectories on parallel runways, modelling the conflict detection and resolution in presence of curved trajectory and radius-to-fix merging process. After that, a suitable mathematical optimization formulation is built up. Receding Horizon Control (RHC) and Simulated Annealing (SA) algorithms are proposed to search the near-optimal solution for the large scale trajectories in routine dense operations. Taking Beijing Capital International Airport (BCIA) as a study case, the experimental results show that our system shows good performances on the management of arrivals and departures. It can automatically solve all the potential conflicts in presence of dense traffic flows. With its unique ML-PM route network, it can realize a shorter flying time and a near-Continuous Descent Approach (CDA) descent for arrival aircraft, an economical climbing for departure aircraft, an easier runway allocation together with trajectory control solutions. It shows a good and dynamic sequencing efficiency in Terminal Manoeuvring Area (TMA). In mixed ML-PM mode, under tested conditions, our proposed system can increase throughput at BCIA around 26%, compared with baseline. The methodology defined here could be easily applied to airports worldwide.     

客车捎带模式下高铁快捷货物输送方案研究

以提高高铁快运当日达产品的时效性、收益率为核心,对既有载客动车组捎带模式下的快捷货物输送方案进行优化。借助时空网络以列车运行成本与时间惩罚费用之和最小为目标,同时满足货主时限、列车容量以及列车停站方案等约束,建立输送方案优化模型,通过匈牙利算法,并借助Matlab的Yalmip工具箱求解模型。以兰州西站至天水南站、宝鸡南站及西安北站部分时间段的快捷货物运输需求为背景进行算例分析,验证模型的有效性。结果表明合理估算列车装载容量及货物的延迟时限对输送方案的选择起重要作用。     

舰船加筋板局部强度评估中的总纵应力折减系数研究

舰船加强筋尺寸的合理确定一直是结构设计中的热点问题。本文综合考虑总纵弯曲应力和局部载荷的相互作用,研究加强筋的许用应力折减系数(C_s)的影响因素与合理取值方法。通过分析加强筋的力学模型、对比不同规范中的C_s取值,以及用非线性有限元软件Abaqus计算一系列加筋板模型,拟合C_s曲线并与规范对比,并验证剖面对称性和局部载荷作用方向对C_s取值的影响方式,丰富了舰船局部强度校核方法的技术背景,为板架设计、舰船三维局部校核程序开发提供借鉴。