不确定性条件下的设备替换优化的 随机动态规划方法

本文提出了一种解决设备更新换代优化（ERO）问题的随机动态规划（SDP）模 型,用以明确地解释在车辆利用中的不确定性,并采用 Bellman 算法解决 ERO SDP 问题. 针对 SDP 状态空间的增长,提出了特殊简化算法,以解决动态规划方法中固有的“维数 灾”问题,确保所需的内存和计算时间不会随着时间范围的增加而成倍增长.并对 SDP 软 件的实现技术、功能和图形用户界面（GUI）进行了讨论,开发了基于 SDP 的 ERO 软件, 并使用美国得克萨斯交通局（TxDOT）现有车辆数据进行验证.对统计结果、软件计算时 间和求解效果进行综合分析,结果显示,使用该 ERO 软件,估计大量成本可以节省.     

When the internet is not enough: toward an understanding of carpool services for service workers

For much of the twentieth century, the economies of Canada and the United States have increasingly focused on service provision. During this same time period, cities have grown into expansive urban regions characterized by dispersed workplaces complemented by a wide array of commuting patterns, dominated by single occupancy vehicle use. This study aims to understand how service worker engagement with an Internet-based carpool formation software, known as Carpool Zone, and workplace transport policies, jointly enable carpool formation and use. The piece also explores the question of difference in carpool formation between female and male service workers. The study area is the Greater Golden Horseshoe, Canada??s largest metropolitan region. Data were drawn from Carpool Zone and a 2007 survey of commuter satisfaction. Extending past work, logistic regression analysis clarifies the importance of specific workplace policies, enacted within suburban firms, to the carpool formation process, including: provision of carpool spaces and availability of an emergency ride home service. The findings indicate that the Internet may not be enough, powerful enabling tools should be situated within expert networks of human capital developed to ameliorate the negative effects of commuting.     

发动机无法启动的快速诊断

每一台汽油发动机要想顺利地启动和正常运转,就需要具备电火花、燃油和汽缸压缩压力这三个基本要素。当一台汽油发动机无法启动时,采用适当的诊断方法,遵循正确的诊断步骤,将有助于你快速确定出哪儿出了问题,以及为什么会出现这样的问题。     

Catching a ride on the information super-highway: toward an understanding of internet-based carpool formation and use

Fluctuating fuel prices, rising congestion, longer commutes, and related environmental and human health effects have combined to once more draw the interest of governments, commuters, and firms toward the concept of travel demand management (TDM). While TDM is not new, the proliferation of mobile telephony, fixed Internet, and associated applications has created fresh prospects for the implementation of commuter focused TDM strategies. One recent example is Carpool Zone, an on-line carpool-matching tool deployed and managed by the TDM group at Metrolinx, the regional transportation planning agency within Canada’s largest metropolitan region, the Greater Toronto and Hamilton Area. Using data provided by Metrolinx, this paper broadens current thinking on carpool formation and use. The main hypothesis guiding this work is that the carpool formation and use process is sensitive to personal and household characteristics, space, time, travel cost, and workplace TDM policies. Results from a logistic regression analysis suggest that geographical proximity to other users; workplace TDM policies; the scheduling of work; and commuter role preference increase the odds of successfully carpooling. Importantly, findings regarding the positive influence of workplace TDM policies suggest that Internet based TDM tools will likely require critically important investment in human capital at the back-end to ensure program participation.     

Dynamics Performance of Subgrade-Tunnel Transition on Chongqing-Suining Ballastless Track

Experiments were conducted on China railway high speed electrical multiple units (EMUs) CRH2 and freight car C80 on Chongqing-Suining high-speed ballastless track. Based on the experimental results, the dynamics performance of cement concrete transition and cement stabilized aggregate transition was analyzed. The results show that the dynamic stress, vibration displacement, vibration velocity, vibration acceleration and other vibration parameters vary steadily on the profile section of transitions, and that at the adjoining position between subgrade and tunnel portal, cement concrete transition has gradual hardness change, whereas cement stabilized aggregate transition exhibits good elasticity, small shock, and small dynamic effect of the cars.     

混合动力汽车对E/E架构提出的挑战

混合动力汽车技术日新月异的趋势不会改变,因此对屏蔽导线的需求也会日益上升。汽车制造商将继续使用电子设备降低重量和节省成本,因此他们需要继续降低这些电子设备产生的噪声。     

Evaluation of Shock Absorber Models

A non exhaustive overview of shock absorber models is presented. The ability of the models to match experimental data is emphasized. Two physical models are presented that are able to extract the internal valve parameters from data without hysteresis. In order to implement a model that copes with hysteresis, most models require the numerical solution to a set of nonlinear differential equations. The use of an alternative restoring force method can get round the time consuming iterative simulation and identification routines. The alternative nonparametric method models the force as a function of velocity and acceleration. The theoretical relevance of the model is studied.     

Comparative analysis on dynamic behavior of two HMA railway substructures

A numerical analysis using a finite element program was performed on three structures:hot mix asphalt(HMA) reinforced trackbed(RACS-1),HMA directly supported trackbed(RACS-2),and traditional Portland Cement Concrete(PCC) slab track(SlabTrack).Although the comprehensive dynamic responses of RACS-1 were similar with SlabTrack,HMA layer can positively affect the stress distributions.In particular,the horizontal stresses indicate that the resilience of RACS-1 was improved relative to SlabTrack.In addition,HMA r...