A multi-path progression model for synchronization of arterial traffic signals

To contend with congestion and spillback on commuting arterials, serving as connectors between freeway and surface-street flows, this paper presents three multi-path progression models to offer progression bands for multiple critical path-flows contributing to the high volume in each arterial link. The first proposed model is a direct extension of MAXBAND under a predetermined phasing plan, but using the path-flow data to yield the progression bands. The second model further takes the phase sequence at each intersection as a decision variable, and concurrently optimizes the signal plans with offsets for the entire arterial. Due to the competing nature of multi-path progression flows over the same green duration, the third model is proposed with a function to automatically select the optimal number of paths in their bandwidths maximization process. The results of extensive simulation studies have shown that the proposed models outperform conventional design methods, such as MAXBAND or TRANSYT, especially for those arterials with multiple heavy path-flows. The research results from this study have also reflected the need to collect more traffic pattern data such as major path-flow volumes, in addition to the typical intersection volume counts.     

Airline crew pairing with fatigue: Modeling and analysis

Crew fatigue is one of the main causes of airline accidents. Regulatory authorities such as the Federal Aviation Agency constantly introduce new fatigue regulations, often in the form of hard constraints on the length of duty and rest periods. The complex nature of travel-related fatigue, however, makes it difficult to account for it indirectly through such constraints. Recent studies show that fatigue depends on human factors such as the homeostatic process and the circadian body clock as well as time-zone differences. In this work, we explicitly account for fatigue in crew pairing optimization through the Three Process Model of Alertness, one of the most comprehensive fatigue models available in the literature. We provide a mathematical model for the crew pairing problem that incorporates fatigue and solve it using a column generation approach. Numerical analysis on two real data sets reveals that the proposed approach is able to reduce the crew fatigue levels substantially with minimal impact on cost. In particular, it is shown that hard constraints on fatigue may still lead to high fatigue levels and that jet-lag and time-zone differences have a major impact. The results of the tests also show that some of the rules and regulations in practice may be omitted if the fatigue is accounted for directly.     

Assessing driving pattern factors for the specific energy use of electric vehicles: A factor analysis approach from case study data of the Mitsubishi i–MiEV minicar

Battery electric vehicles (BEVs) promise to contribute to the achievement of a more sustainable transport system. In order to estimate energetic efficiency potentials while taking into account operating conditions, insights on the factors of energy use are required. The driving pattern, i.e. the characteristics of the driving profile, is expected to affect the vehicles’ energy use to a great extent. This paper investigates whether the driving pattern parameters that have proved to be relevant for the fuel consumption of ICVs also apply to BEVs. In consequence, we analyse correlations between driving pattern factors and the specific energy use of BEVs. In order to record driving and energy data, four commercially used battery electric minicars were equipped with tracking devices. The resulting dataset contains 42 vehicle months. The driving pattern is described in 45 parameters that are calculated for segments of the logged driving profiles. Exploratory factor analysis is applied to reduce the large number of parameters into a smaller number of independent factors. Six independent driving pattern factors are identified. Suitable correlation coefficients are calculated to check for dependencies with energy use. The most significant correlations were found for the intensity of acceleration/deceleration, as well as for the oscillation factor. Our results could be used to inform further studies where driving pattern factors for ICVs and BEVs are directly compared. Also, results can be used to develop specific driving school training programs to learn to drive BEVs in an energy efficient manner.     

A column generation algorithm for the bus driver scheduling problem

Bus driver scheduling aims to find the minimum number of bus drivers to cover a published timetable of a bus company. When scheduling bus drivers, contractual working rules must be enforced, thus complicating the problem. In this research, we develop a column generation algorithm that decomposes this complicated problem into a master problem and a series of pricing subproblems. The master problem selects optimal duties from a set of known feasible duties, and the pricing subproblem augments the feasible duty set to improve the solution obtained in the master problem. The proposed algorithm is empirically applied to the realistic problems of several bus companies. The numerical results show that the proposed column generation algorithm can solve real‐world problems and obtain bus driver schedules that are better than those developed and used by the bus companies. Copyright © 2016 John Wiley & Sons, Ltd.     

Using vehicle simulations to understand strategies for accommodating oversize,overweight vehicles at roundabouts

There is considerable evidence that roundabouts are the safest and most efficient form of traffic control for most intersections. The potential use of roundabouts with all their inherent benefits may be greatly diminished if they are not able to accommodate oversize/overweight (OSOW) vehicles, sometimes called “Superloads.” The problem, therefore, is how to accommodate OSOW vehicles without sacrificing the integrity, safety and other benefits of roundabouts.This study uses TORUS software to design six standard roundabouts using guidance from the latest Federal Highway Administration (FHWA) roundabout guide. Six OSOW check vehicles from the Wisconsin Department of Transportation’s library were used to modify the designs to accommodate these selected check vehicles at the roundabouts. These six OSOW check vehicles were used to conduct swept path analysis using AutoTURN software at the selected six standard roundabouts for right turn, through, and left turn simulations. The space requirements for these maneuvers were analyzed in detail. Various strategies for better accommodating these OSOW check vehicles were suggested and experimented with in this study using AutoTURN software simulations. The effectiveness of using a straight passage through the center island for OSOW vehicles was also addressed in this study and was found to be effective. All the strategies investigated in this study proved to be effective in accommodating OSOW vehicles when compared to conventional ways of using a roundabout. The needed total truck apron was calculated and used as a reference to determine an effective strategy for accommodating OSOW vehicles. This research can be used as guidance for transportation engineers, planners and decision makers to determine possible ways of designing a roundabout at an intersection where certain OSOW vehicles are expected.     

离合踏板抖动原因分析与控制

针对某乘用车离合器踏板在离合器半接合状态下抖动的问题,对离合器踏板进行振动特性和振源分析。提出相应的控制对策和实施方案,并对实施方案效果进行验证。结果表明,实施控制方案后,离合器踏板接合平顺性得到有效改善,为解决同类问题提供参考。     

船体纵骨疲劳裂纹扩展及寿命分析

基于有限元软件ABAQUS,结合虚拟裂纹闭合法、裂纹扩展判据及子结构技术,应用脚本语言Python开发了模拟疲劳裂纹扩展的程序(FCG-System)。对含初始裂纹的油船纵骨节点疲劳裂纹扩展进行数值模拟,并探讨侧向压力和轴向拉力这两种载荷对疲劳裂纹扩展路径和疲劳寿命的影响。结果表明,两种加载方式下裂纹扩展路径不同,且面板断裂前的疲劳寿命在总寿命中占据很大的成分。     

Global Inverse Optimal Tracking Control of Underactuated Omni-directional Intelligent Navigators (ODINs)

This paper presents a design of optimal controllers with respect to a meaningful cost function to force an underactuated omni-directional intelligent navigator (ODIN) under unknown constant environment...     

基于BP神经网络的图像识别跟踪技术

本文利用BP神经网络抗干扰性强,识别精准等优点对船舶进行识别跟踪。首先获取原始图像,然后预处理,以图像的全部灰度值为训练样本,以新不变矩特征向量为样本集输入到3层BP神经网络中,对含不同噪声均值的图像进行识别。实验结果表明,以新不变矩特征向量作为样本集时抗噪能力强,识别率高。最后以新不变矩特征向量作为样本集进行目标跟踪得到跟踪误差。     

干扰及参数扰动条件下的航迹镇定滑模控制

以欠驱动船舶船迹控制应用为背景,提出一种在外界干扰和参数扰动条件下的船舶镇定滑模控制算法。为有效抑制常规滑模控制器的抖振,提高在受到外部环境干扰和参数摄动时的鲁棒性,提出基于BP神经网络的非线性自抗扰滑模控制算法。仿真结果表明,该方法能够有效应对风流干扰,具有很好的鲁棒性。