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为解决供水行业中供水管道漏损安全性问题,建立了供水管道漏损安全预测模型,并引入遗传算法对其优化进行漏损预测,同时,针对传统的遗传算法优化该模型的过程中出现的缺陷,提出了混合遗传算法对其求解.模拟实例的预测结果表明:该模型预测方法准确可靠,具有较高的实用性。 相似文献
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基于OSM路网、百度地图实景、POI、百度热力等多源时空数据,运用绕行系数PRD值分析法、空间分析法、对比分析法,构建城市中心区轨交站域慢行接驳空间特征分析方法,确定轨交站域影响范围,分析站域慢行接驳空间便捷性,剖析时空特征视角下的轨交站点出入口活力特征,挖掘轨交站域慢行接驳空间品质特征。在明确慢行接驳空间优化原则的基础上,从居住区出入口、路权、静态交通、导视系统、辅助设施等方面优化设计,通过空间模型法可视化表达,营造畅行连续、空间宜人、绿色友好的轨交站域慢行接驳环境。 相似文献
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精益物流配送活动中出现的一类散户配送问题是典型的组合优化问题,利用传统的优化方法计算复杂、难以求得全局最优解,遗传算法在求解这类问题中表现出了强劲的优势.利用遗传算法对这类特殊问题进行了研究分析,针对具体的配送问题进行了仿真试验,在实验的基础上探索了交叉算子、变异算子的优化设计,实验结果证明了遗传算法在解决这类问题上的可行性和有效性. 相似文献
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轨道交通出行与多种出行方式有效衔接,不仅能充分发挥轨道交通的运输能力,且可以有效利用低碳、环保的出行工具。通过建立接驳方式选择模型,可以研究接驳方式选择概率与多要素之间的关系。本文以厦门市为例,研究使用Kirchhoff分布方程建立接驳方式选择模型,并考虑综合出行成本对选择概率的影响,该方法具有考虑各接驳方式综合成本相对差异、计算简单的优势。结果表明:该方法能够较好地分析轨道交通站点的接驳方式选择,合理推导出站点周边接驳出行选择概率与出行距离的关系,能够一定程度反映接驳需求的空间分布。 相似文献
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为实现对纳米SiO2改性陶粒混凝土抗压强度和干缩值两项技术指标的预测,基于大量试验数据,以水胶比、纳米SiO2掺量、陶粒用量为模型输入参数,提出了一种基于遗传算法优化改进的神经网络模型。结果表明,相比较于传统的回归分析法,经遗传算法优化的神经网络预测模型的拟合优度值(R2)超过了0.9,也可以更准确和稳定地预测纳米SiO2改性陶粒混凝土的各项性能,该方法为解决绿色混凝土材料的配合比优化与性能调控问题提供了新思路。 相似文献
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山东省交通运输集团结合当地的实际情况,建立了高速公路客运接驳站——济青高速刁镇客运站,解决了当地群众上高速路、乘车难的问题。文章论述了建设高速公路客运接驳站的必要性,介绍了高速客运接驳站的选址与服务形式、安全与服务管理情况、以及使用效果与发展前景。 相似文献
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《西部交通科技》2017,(12)
城市高峰期交通拥堵呈常态化趋势,各运输路段的通行时间很难用精确值表达,而配送车辆的路径仍需具体指定,亟需研究路段通行时间不确定情况下的物流配送车辆的具体运输路径。文章统筹考虑配送时间与环境成本,结合Bertsimas鲁棒离散优化理论,以总行程时间和碳排放量最小为优化目标,构建了路段时间阻抗不确定情况下的同时取送货多配送中心多车路径鲁棒优化模型,采用遗传算法进行求解,并以呼和浩特市部分路网为例进行实证研究。研究结果表明:车辆路径鲁棒优化模型及其改进的遗传算法能快速生成鲁棒性能较好的车辆行驶路径,而且得到的是一条条具体的运输路径,而非配送顺序。该模型与算法能为物流配送车辆路径导航系统提供技术支撑。 相似文献
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Abstract This paper investigates a transportation scheduling problem in large-scale construction projects under a fuzzy random environment. The problem is formulated as a fuzzy, random multi-objective bilevel optimization model where the construction company decides the transportation quantities from every source to every destination according to the criterion of minimizing total transportation cost and transportation time on the upper level, while the transportation agencies choose their transportation routes such that the total travel cost is minimized on the lower level. Specifically, we model both travel time and travel cost as triangular fuzzy random variables. Then the multi-objective bilevel adaptive particle swarm optimization algorithm is proposed to solve the model. Finally, a case study of transportation scheduling for the Shuibuya Hydropower Project in China is used as a real world example to demonstrate the practicality and efficiency of the optimization model and algorithm. 相似文献
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《Transportation Research Part A: Policy and Practice》2002,36(3):203-223
In the expressway network, detectors are installed on the links for detecting the travel time information while the predicted travel time can be provided by the route guidance system (RGS). The speed detector density can be determined to influence flow distributions in such a way that the precision of the travel time information and the social cost of the speed detectors are optimized, provided that each driver chooses the minimum perceived travel time path in response to the predicted travel time information. In this paper, a bilevel programming model is proposed for the network with travel time information provided by the RGS. The lower-level problem is a probit-based traffic assignment model, while the upper-level problem is to determine the speed detector density that minimizes the measured travel time error variance as well as the social cost of the speed detectors. The sensitivity analysis based algorithm is proposed for the bilevel programming problem. Numerical examples are provided to illustrate the applications of the proposed model and of the solution algorithm. 相似文献
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To study the effect of different transport policies on reducing the average comprehensive travel cost (CTC) of all travel modes, by increasing public transport modal share and decreasing car trips, an optimization model is developed based on travel cost utility. A nested logit model is applied to analyze trip modal split. A Genetic Algorithm is then used to determine the implementation of optimal solutions in which various transport policies are applied in order to reduce average CTC. The central urban region of Beijing is selected as the study area in this research. Different policies are analyzed for comparison, focusing on their optimal impacts on minimizing the average CTC utility of all travel modes by rationally allocating trips to different travel modes in the study area. It is found that the proposed optimization model provides a reasonable indication of the effect of policies applied. 相似文献
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Using the schedule‐based approach, in which scheduled timetables are used to describe the movement of vehicles, a dynamic transit assignment model is formulated. Passengers are assumed to travel on a path with minimum generalized cost that consists of four components: in‐vehicle time; waiting time; walking time; and a time penalty for each line change. A specially developed branch and bound algorithm is used to generate the time‐dependent minimum path. The assignment procedure is conducted over a period in which both passenger demand and train headway are varying. This paper presents an overview of the research that has been carried out by the authors to develop the schedule‐based transit assignment model, and offers perspectives for future research. 相似文献
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In this study, we propose a travel itinerary problem (TIP) which aims to find itineraries with the lowest cost for travelers visiting multiple cities, under the constraints of time horizon, stop times at cities and transport alternatives with fixed departure times, arrival times, and ticket prices. First, we formulate the TIP into a 0–1 integer programming model. Then, we decompose the itinerary optimization into a macroscopic tour (i.e., visiting sequence between cities) selection process and a microscopic number (i.e., flight number, train number for each piece of movement) selection process, and use an implicit enumeration algorithm to solve the optimal combination of tour and numbers. By integrating the itinerary optimization approach and Web crawler technology, we develop a smart travel system that is able to capture online transport data and recommend the optimal itinerary that satisfies travelers’ preferences in departure time, arrival time, cabin class, and transport mode. Finally, we present case studies based on real-life transport data to illustrate the usefulness of itinerary optimization for minimizing travel cost, the computational efficiency of the implicit enumeration algorithm, and the feasibility of the smart travel system. 相似文献
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This paper presents a transit network optimization method, in which travel time reliability on road is considered. A robust optimization model, taking into account the stochastic travel time, is formulated to satisfy the demand of passengers and provide reliable transit service. The optimization model aims to maximize the efficiency of passenger trips in the optimized transit network. Tabu search algorithm is defined and implemented to solve the problem. Then, transit network optimization method proposed in this paper is tested with two numerical examples: a simple route and a medium-size network. The results show the proposed method can effectively improve the reliability of a transit network and reduce the travel time of passengers in general. 相似文献
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The train operational plan (TOP) plays a crucial role in the efficient and effective operation of an urban rail system. We optimize the train operational plan in a special network layout, an urban rail corridor with one terminal yard, by decomposing it into two sub-problems, i.e., the train departure profile optimization and the rolling stock circulation optimization. The first sub-problem synthetically optimizes frequency setting, timetabling and the rolling stock circulation at the terminal without a yard. The maximum headway function is generated to ensure the service of the train operational plan without considering travel demand, then we present a model to minimize the number of train trips, and design a heuristic algorithm to maximize the train headway. On the basis of a given timetable, the rolling stock circulation optimization only involves the terminal with a yard. We propose a model to minimize the number of trains and yard–station runs, and an algorithm to find the optimal assignment of train-trip pair connections is designed. The computational complexities of the two algorithms are both linear. Finally, a real case study shows that the train operational plan developed by our approach enables a better match of train headway and travel demand, and reduces the operational cost while satisfying the requirement of the level of service. 相似文献
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This paper considers the train rescheduling problem with train delay in urban subway network. With the objective of minimizing the negative effect of train delay to passengers, which is quantified with a weighted combination of travel time cost and the cost of giving up the planned trips, train rescheduling model is proposed to jointly synchronize both train delay operation constraints and passenger behavior choices. Space–time network is proposed to describe passenger schedule‐based path choices and obtain the shortest travel times. Impatience time is defined to describe the intolerance of passengers to train delay. By comparing the increased travel time due to train delay with the passenger impatience time, a binary variable is defined to represent whether the passenger will give up their planned trips or not. The proposed train rescheduling model is implemented using genetic algorithm, and the model effectiveness is further examined through numerical experiments of real‐world urban subway train timetabling test. Duration effects of the train delay to the optimization results are analyzed. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
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Byung-Wook Wie Roger L. Tobin Malachy Carey 《Transportation Research Part B: Methodological》2002,36(10)
In this paper, a dynamic user equilibrium traffic assignment model with simultaneous departure time/route choices and elastic demands is formulated as an arc-based nonlinear complementarity problem on congested traffic networks. The four objectives of this paper are (1) to develop an arc-based formulation which obviates the use of path-specific variables, (2) to establish existence of a dynamic user equilibrium solution to the model using Brouwer's fixed-point theorem, (3) to show that the vectors of total arc inflows and associated minimum unit travel costs are unique by imposing strict monotonicity conditions on the arc travel cost and demand functions along with a smoothness condition on the equilibria, and (4) to develop a heuristic algorithm that requires neither a path enumeration nor a storage of path-specific flow and cost information. Computational results are presented for a simple test network with 4 arcs, 3 nodes, and 2 origin–destination pairs over the time interval of 120 periods. 相似文献
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The methodology presented here seeks to optimize bus routes feeding a major intermodal transit transfer station while considering intersection delays and realistic street networks. A model is developed for finding the optimal bus route location and its operating headway in a heterogeneous service area. The criterion for optimality is the minimum total cost, including supplier and user costs. Irregular and discrete demand distributions, which realistically represent geographic variations in demand, are considered in the proposed model. The optimal headway is derived analytically for an irregularly shaped service area without demand elasticity, with non‐uniformly distributed demand density, and with a many‐to‐one travel pattern. Computer programs are designed to analyze numerical examples, which show that the combinatory type routing problem can be globally optimized. The improved computational efficiency of the near‐optimal algorithm is demonstrated through numerical comparisons to an optimal solution obtained by the exhaustive search (ES) algorithm. The CPU time spent by each algorithm is also compared to demonstrate that the near‐optimal algorithm converges to an acceptable solution significantly faster than the ES algorithm. 相似文献