A hybrid optimization-simulation approach for robust weekly aircraft routing and retiming

We address the robust weekly aircraft routing and retiming problem, which requires determining weekly schedules for a heterogeneous fleet that maximizes the aircraft on-time performance, minimizes the total delay, and minimizes the number of delayed passengers. The fleet is required to serve a set of flights having known departure time windows while satisfying maintenance constraints. All flights are subject to random delays that may propagate through the network. We propose to solve this problem using a hybrid optimization-simulation approach based on a novel mixed-integer nonlinear programming model for the robust weekly aircraft maintenance routing problem. For this model, we provide an equivalent mixed-integer linear programming formulation that can be solved using a commercial solver. Furthermore, we describe a Monte-Carlo-based procedure for sequentially adjusting the flight departure times. We perform an extensive computational study using instances obtained from a major international airline, having up to 3387 flights and 164 aircraft, which demonstrates the efficacy of the proposed approach. Using the simulation software SimAir to assess the robustness of the solutions produced by our approach in comparison with that for the original solutions implemented by the airline, we found that on-time performance was improved by 9.8–16.0%, cumulative delay was reduced by 25.4–33.1%, and the number of delayed passengers was reduced by 8.2–51.6%.     

试论大学英语课堂活动的有效策划

随着教学改革的不断深入,英语教师越来越重视活动在课堂中的运用。本文首先分析了大学英语课堂活动中存在的问题,再从五个方面提出了策划课堂活动时提高活动有效性的原则及改进方法,这五个方面分别是:明确活动的目标性、加强活动实用性、确保活动的可行性、把握活动的可控性、提高活动的参与性。     

基于生命周期理论的我国收费公路发展分析

收费公路类似自然生命,其成长和发展必然为一个具有若干阶段的连续过程。基于生命周期理论,对我国收费公路体系生命周期进行了探讨和分析。结果表明,2000年以后,我国收费公路进入成熟期;在2030年达到峰值后,收费公路在总量上开始缩减,进入衰退期,新的发展趋势也将逐渐体现。     

The use of demand correlation in the modeling of air carrier departure delays as first‐order autoregressive random processes

A method for modeling air carrier departure delays at commercial‐service airports as autoregressive random processes is presented. This method employs the correlation of a priori demand data to significantly reduce prediction error in the optimal least‐squares estimator for additive white noise. The reduction factor of the prediction error is demonstrated to be on the order of 10² over that of the unbiased estimator. Copyright © 2011 John Wiley & Sons, Ltd.     

Support for Oregon land‐use planning: A multi‐level analysis

Abstract

This article analyzes support for and opposition to state land‐use planning in Oregon, using voting records from the 1976 referendum to repeal Oregon's regulatory legislation and survey data. Support for controlled growth legislation is found to be a product of both individual‐level characteristics and characteristics of the larger community where one resides. The most influential contextual variables are the county's economy and the class composition of the city. The authors conclude that coastal zone managers must exercise caution when interpreting individual survey data which indicate support for various environmental concerns. Contextual differences must be taken into consideration because sources of support for coastal zone management may vary among individuals, depending on the nature of the communities in which they live.     

Privacy protection method for fine-grained urban traffic modeling using mobile sensors

With the ubiquitous nature of mobile sensing technologies, privacy issues are becoming increasingly important, and need to be carefully addressed. Data needs for transportation modeling and privacy protection should be deliberately balanced for different applications. This paper focuses on developing privacy mechanisms that would simultaneously satisfy privacy protection and data needs for fine-grained urban traffic modeling applications using mobile sensors. To accomplish this, a virtual trip lines (VTLs) zone-based system and related filtering approaches are developed. Traffic-knowledge-based adversary models are proposed and tested to evaluate the effectiveness of such a privacy protection system by making privacy attacks. The results show that in addition to ensuring an acceptable level of privacy, the released datasets from the privacy-enhancing system can also be applied to urban traffic modeling with satisfactory results. Albeit application-specific, such a “Privacy-by-Design” approach would hopefully shed some light on other transportation applications using mobile sensors.     

高速公路大修工程施工区安全与交通组织研究

进行大修的高速公路,大多是所在区域的运输干道和交通骨架,交通量往往很大,交通环境复杂,如果对交通组织研究得不够,会导致施工时交通组织混乱,严重影响施进度和施工区的安全,还会造成长时间交通拥堵等被动局面.对高速公路大修施工路段事故原因、交通组织方案和交通分流的分析,对于确保施工的顺利实施以及驾驶员和施工人员安全具有重要意义.     

舰船物资转运方案计算机辅助决策算法研究

瞬息万变的现代战场对大中型水面战斗舰船甲板物资转运的效率提出越来越高的要求。引入计算机辅助决策技术,在考虑多种牵制因素的情况下,快速获得最优的物资转运方案。详细分析和阐述舰船物资转运线路规划、时间计算、作业排序以及资源配班等4个主要问题的计算机解决方法,为利用计算机辅助制定最优物资转运方案提供可行途径。     

大型机场地面集疏运需求预测方法研究

机场地面集疏运系统是机场发展的重要支撑，交通需求预测是进行机场集疏运交通规划的前提。笔者以四阶段预测的基本原理为基础，结合机场集疏运需求特点，对预测的整体思路、方法、步骤和内容等进行详细分析，优化调整出行分布、方式划分预测模型，并以南京禄口国际机场为实例进行了预测。研究成果对国内同类大型机场的集疏运需求预测具有借鉴和参考价值。