舰载直升机对潜跟踪兵力需求研究

从解决舰载直升机对潜跟踪时兵力需求问题出发,运用运筹分析的思想,通过对舰载直升机对潜跟踪过程的分析,建立了在一定跟踪概率前提下所需舰载直升机数量的计算模型。     

城市轨道交通虚拟编组列车快慢车组织方案研究

虚拟编组技术的发展为改进城市轨道交通快慢车组织提供可能,有望缓解传统模式中慢车旅行时间增加、线路通过能力损失等问题.分析虚拟编组技术下列车运行的典型作业过程,给出虚拟编组条件下车站间隔时间的计算公式.提出虚拟编组技术下无越行和有越行两种快慢车的运行组织策略,对比不同组织模式下列车的开行效果,并进行案例分析.计算结果表明...     

嵌岩桩极限承载力理论分析与试验研究

综合分析了国内规范中嵌岩桩极限承载力理论计算的优缺点（特别是新版《公路桥涵地基基础规范》）,并结合青岛胶州湾大桥软岩嵌岩桩的自平衡试桩资料,将试桩极限承载力测试结果与现行规范极限承载力计算值进行了比较研究。     

Development and evaluation of a hybrid travel time forecasting model

The purpose of this paper is to develop and evaluate a hybrid travel time forecasting model with geographic information systems (GIS) technologies for predicting link travel times in congested road networks. In a separate study by You and Kim (cf. You, J., Kim, T.J., 1999b. In: Proceedings of the Third Bi-Annual Conference of the Eastern Asia Society for Transportation Studies, 14–17 September, Taipei, Taiwan), a non-parametric regression model has been developed as a core forecasting algorithm to reduce computation time and increase forecasting accuracy. Using the core forecasting algorithm, a prototype hybrid forecasting model has been developed and tested by deploying GIS technologies in the following areas: (1) storing, retrieving, and displaying traffic data to assist in the forecasting procedures, (2) building road network data, and (3) integrating historical databases and road network data. This study shows that adopting GIS technologies in link travel time forecasting is efficient for achieving two goals: (1) reducing computational delay and (2) increasing forecasting accuracy.     

Numerical study on flow structure of a shallow laminar round jet

The evolution mechanism and characteristics of the submerged laminar round jet in a viscous homogenous shallow water layer are investigated through computational modeling. The laminar mode is used to solve the Navier-Stokes equations. In order to visualize the formation and evolution of the flow pattern, the volume of fluid (VOF) method is adopted to simulate the free surface of the water layer below the air and to trace the jet fluid. The results show that the jet forms a class of quasi-two-dimensional (Q2D) vortex structures in the ambient fluid with unequal influence from the bottom wall and free surface. The time dependence of three parameters, defined for the flow pattern as jet length, spiral radius and pattern length, is investigated quantitatively in their non-dimensional forms. Three different Reynolds numbers and two injection durations are further considered to discuss their influence on the flow pattern.     

Statistical inference on transit route‐level origin–destination flows using automatic passenger counter data

We consider inferring transit route‐level origin–destination (OD) flows using large amounts of automatic passenger counter (APC) boarding and alighting data based on a statistical formulation. One critical problem is that we need to enumerate the OD flow matrices that are consistent with the APC data for each bus trip to evaluate the model likelihood function. The OD enumeration problem has not been addressed satisfactorily in the literature. Thus, we propose a novel sampler to avoid the need to enumerate OD flow matrices by generating them recursively from the first alighting stop to the last stop of the bus route of interest. A Markov chain Monte Carlo (MCMC) method that incorporates the proposed sampler is developed to simulate the posterior distributions of the OD flows. Numerical investigations on an operational bus route under a realistic OD structure demonstrate the superiority of the proposed MCMC method over an existing MCMC method and a state‐of‐the‐practice method. Copyright © 2015 John Wiley & Sons, Ltd.     

An improved incremental assignment model for parking variable message sign location problem

Operators and planners of parking guidance and information system (PGIS) often encounter the difficulty when and how to provide parking information to drivers in peak hours. The aim of this study was to assign the parking demands onto the urban network, find the positions suitable to locate the parking variable message sign (parking VMS), and try to solve the problem when to provide parking information to drivers. Parking VMS, as the most common forms of the information display terminal of PGIS, becomes critical in designing PGIS. This paper started from analyzing the relationship between the location and the performances of parking VMS. If a parking VMS is placed right along the link approaching to the divarication intersection of the subsequent “shortest path” and the previous one, the travel time declines abruptly, and the guiding compliance ratio becomes superior. Then, the network‐based parking choice model for the parking VMS was proposed. Network modification and incremental assignment were used to find the divarication intersections caused by the changes of space availability. In addition, MATLAB software package (MathWorks, Inc., Natick, MA, USA) was adopted to calculate the entire process mentioned. The proposed model and the algorithm were applied to a numerical example, where the location of parking VMS was obtained. Copyright © 2015 John Wiley & Sons, Ltd.     

我国铁路货运价格策略研究

运价是影响客户选择运输方式的主要因素之一。结合铁路自身的优势,应用铁路货运价格理论,借鉴美国的运价策略,提出了新产品定价、产品组合定价、折扣和让价、价外收费等策略。     

抓斗卸船粉尘的治理

研究港口干散货装卸作业中扬尘产生的机理和控制措施,介绍基于插入式布袋除尘器的卸料漏斗除尘系统,提出了抓斗卸料漏斗除尘系统的设计思想与方法.     

汽车经销商销售能力提升的系统研究

在分析经销商销售能力提升对汽车生产商重要意义的基础上,剖析了经销商销售服务核心流程及其关键作用,并进行了经销商销售能力提升的3方面因素研究。