Uncertainty in traffic forecasts: literature review and new results for The Netherlands

This paper provides a review of transport model applications that not only provide a central traffic forecast (or forecasts for a few scenarios), but also quantify the uncertainty in the traffic forecasts in the form of a confidence interval or related measures. Both uncertainty that results from using uncertain inputs (e.g. on income) and uncertainty in the model itself are treated. The paper goes on to describe the methods used and the results obtained for a case study in quantifying uncertainty in traffic forecasts in The Netherlands.

Electric vehicles in car sharing networks – Challenges and simulation model analysis

In this paper, we examine the operation of electric vehicles in urban car sharing networks. After surveying strategic and operational differences and comparing them to gasoline-fueled cars, a simulation study was carried out. The proposed discrete event simulation tool covered important operational characteristics of electric vehicles, including realistic charging routines. Different vehicle types were compared under various conditions and on multiple markets to determine their performance. The data obtained indicated the competitiveness of electric vehicles in car sharing networks. Key success factors included advantageous relations between the market environment (e.g. electricity and fuel prices) and important characteristics of electric cars (e.g. price and range).     

An investment appraisal method to compare LNG-fueled and conventional vessels

Ever stricter emission regulations stimulate vessel owners to consider the adoption of alternative marine fuels, such as Liquefied Natural Gas (LNG). In deciding whether to invest in LNG-fueled vessels, initial investment and operating costs are decisive factors that have not yet been fully studied in the literature. In this paper, we present a new investment appraisal method to compare the costs of LNG-fueled vessels with conventional vessels. We analyze the fuel costs and overall exploitation costs by simulating bunker planning decisions under stochastic fuel prices, presence in emission controlled areas, and route lengths. Our analyses reveal that the fuel costs of LNG-fueled vessels are often lower than those of conventional vessels, even under unfavorable LNG prices. Due to the higher initial investment costs in LNG-fueled vessels, these fuel cost reductions do not always translate into lower overall exploitation costs. By conducting numerical experiments, we identified conditions under which the exploitation costs of LNG-fueled vessels are lower than conventional vessels.     

An agent-based multimodal simulation model for capacity planning of a cross-border transit facility

Cross-border transit facilities constitute major public investment, and thus must serve the long-term needs of the communities, such as providing access to schools and businesses, contributing to a shared regional culture and lifestyle, fostering international trade, and supporting jobs for the region’s residents. Numerous studies have been conducted to evaluate the economic implications of vehicular flow delays at border crossings, however none of the studies focused on assessing cross-border flow of bus passengers and pedestrians. Since pedestrians are considered to be autonomous, intelligent, and perceptive, it is a challenging task to predict pedestrian movement and behavior in comparison to vehicular flows which follow a specific set of traffic rules. This paper presents a multiagent based multimodal simulation model to evaluate the capacity and performance of a cross-border transit facility. The significance of this research is the use of dynamic mode choice functionality in the model, which allows an individual person to make instantaneous choices between available modes of transportation. The scope of interest of the paper is limited to simulating access interface, circulation areas, ancillary and processing facilities. The developed model was calibrated to ensure realistic performance, and validated against specific performance criteria such as throughput per processing facility. In order to demonstrate the applicability of the developed simulation model, capacity and operational planning of a pedestrian transit facility was performed. The relative performance of alternative design or configuration was evaluated using the level of service criteria. Lastly, the effectiveness of each proposed capacity or operational improvement strategy was compared to the “do-nothing” scenario.     

Case studies of shipping along Arctic routes. Analysis and profitability perspectives for the container sector

Arctic sea routes have for long attracted interest from observers and shipping companies because of their shorter distances between the Atlantic and the Pacific. The prevalence of sea ice prevented the real development of a significant traffic, but did not prevent research from trying to assess the economic viability of these routes. With the actual present melting of sea ice in the Arctic, this effort at modeling the profitability of Arctic shipping routes received a new impetus. However, the conclusions of these studies vary widely, depending on the chosen parameters and their value. What can be said of these models, from 1991 until 2013, and to what extent can a model be drawn, capitalizing on twenty years of simulations?     

汽车车身板料冲压成形分析与模拟

本文综述了车身板料冲压成形分析与模拟的产生，发展和基本方法，及其对优化冲压工艺过程，降低生产成本和缩短开发周期所起的重要作用，文中着重介绍了板料成形分析与模拟的基本数值方法－逐步更新Ｌａｇｒａｎｇｅ方法（Ｕ．Ｌ．法）以及关于车身覆盖件的数值例子，并指出了今后研究中值得强调和注意的一些问题。     

汽车电子防抱制动系统仿真的研究

本文分析了汽车车轮制动瞬态动力学，结合精确的１５自由度空间刚体动力学模型，定量地分析了车轮抱死松开所获得的加减速度值，并为防抱制动提供了准确的加减速度阈值，同时考虑到防抱制动系统本身装置的特性，提出了最佳又符合实际的制动矩控制参数，使用仿真结果更接近实际，为电子防抱制动系统的研究提供较完整的理论体系和分析方法，并开发了汽车电子防抱制动系统模型（ＨＶＯＳＭ－ＡＢＳ）及模拟程序，该程序具有１６种不同的     

汽车全工况操纵和制动动力学17自由度的建模与仿真

本文描述了１７自由度汽车全工况操纵与制动过程动力学模型的建模，仿真与验证。该模型考虑了侧风，有无防抱系统，高速，变车速，双移线转变制动等各种极端工况，仿真结果与美国密执安大学的仿真结果十分吻合，证实了该算法与模型具有很好的精度。     

气囊模拟计算技术综述

安全气囊模拟计算技术是研究气囊与假人相互作用的有效手段。常用的计算 双压法和压力温度法等，可以采用直接折叠法或始使短阵法建立气囊的有限元模型。现在有的折叠方式如星形叠法用传统的建模方法已有能解决，而考虑气体流动的气囊欧拉模型将得到更广泛的应用。     

用神经网络仿真驾驶员转向特性的研究

在人－车－环境综合系统中，由于驾驶员操作因素的不确定性和非线性，政难以建立精确模型。通过使用神经网络的方法对驾驶员的转向操作进行了模拟和仿真，取得了满意的结果，为更加精确定量地分析驾驶员的转向操作特性提供了一条新的途径。