Application of genetic algorithms for joint optimization of signal setting parameters and dynamic traffic assignment for the real network data

This paper presents the joint optimization of signal setting parameters and dynamic user equilibrium (DUE) traffic assignment for the congested urban road network. The simulation-based approach is employed to obtain the DUE condition for the case of multiple-origin multiple-destination traffic flows. The dynamic traffic assignment simulation program (DTASP), developed in C language is used to assign the traffic dynamically on the road network, whereas method of successive averages (MSA) is modified and used to arrive at the DUE condition. The artificial intelligence technique of genetic algorithms (GAs) is applied to obtain the optimal signal setting parameters and path flow distribution factor for DUE condition. The methodology developed in such a way that joint optimization of signal setting parameters with DUE is obtained. The proposed method is applied to the real network data of Fort Area of Mumbai city comprising of 17 nodes and 56 unidirectional links with 72 Origin–Destination pairs, where all the 17 nodes are signalized intersections. The traffic flow condition for the optimized signal setting parameters is considerably improved compared to the existing signal settings. The results prove that the GA is an effective technique to solve the joint optimization problem for the real network data.     

A reactive container rerouting model for container flow recovery in a hub-and-spoke liner shipping network

This paper focuses on the container rerouting due to a disruption, aims at making the optimal container flow recovery plan for the affected liner shipping company. First, we make the initial effort to bring up with a basic framework of disruption management for liner shipping. Second, we present a compact integer linear programming model for addressing the container rerouting problem under the proposed framework in a hub-and-spoke liner shipping network, based on a given recovery vessel schedule that determines to omit a port of call. Other shipping companies’ services and other modes (roadway, railway, and airline) as candidate alternative means to transport the miss-connected containers are also incorporated in the proposed model. The container flow recovery plan would select the optimal alternative paths for the miss-connected containers balancing the trade-off between container transport costs and delivery delay penalty costs. Finally, a case study from a global liner shipping company is investigated and the computational results indicate the model can be solved effectively and efficiently for the real-scale problem. Thus, the proposed approach in this paper can supply real-time decision support tool for the liner shipping operators on handling the process of container flow recovery.     

沿海、内河货物运输合同关系新探

沿海、内河货物运输合同关系,在法律适用方面,以《合同法》和《民法通则》为基本标尺,以《国内水路货物运输规则》为基本规范。相关货运合同的签订,遵循《合同法》规定的要约与承诺方式,运单是运输合同的证明和承运人已经接收货物的收据。未取得《水路运输许可证》的水运企业所签的沿海、内河货物运输合同,应依法认定为有效合同,但这不影响水运行政主管机关对有关承运人追究行政责任。     

一种求解结构可靠度的新型计算方法

提出了一种求解结构可靠度的软计算方法,该方法综合了人工神经网络的柔软性和遗传算法的全局性及并行快速性的优点.利用人工神经网络的柔软性,可以生成任意形状的函数,因而可以更加贴切地拟合功能函数;由于遗传算法具有并行处理能力,可以对多组样本同时进行处理,因此收敛速度加快.除此之外,文中的遗传算法还使用了小生境共享技术,有效地克服了陷入局部解的缺陷.并根据上述方法研制了结构可靠度分析的电算程序,算例计算表明,计算结果具有很高的精度,该算法为结构可靠度研究提供了一种新的思路和实现路径.     

Application of a genetic algorithm to the optimal structural design of a ship's engine room taking dynamic constraints into consideration

The genetic algorithm, known as GA, is used to optimize engine room structure, not only under static constraints, but also under dynamic constraints. A penalty function method is used to handle the complicated constraint conditions based on the numerical results of dynamic and static analyses. There are several ways to take the dynamic effect into account in the optimum design of ship structure. First, the inequality constraint condition is applied to separate the natural frequency and the exciting frequency. Second, generalized design variables are introduced in order to transfer not only the dynamic but also the static equilibrium equations into the equality constraints, resulting in the optimal structural design without the need to solve these equilibrium equations. Third, the magnitudes of the acceleration and displacement are constrained instead of applying the natural frequency constraint condition. In order to achieve better convergency in the optimization with least resources, several operators and methods are considered and then introduced into the structural design of the engine room. The new operator, called either objective elitism or fitness elitism, is introduced to improve the efficiency of the method. The effect of boundary mutation and nonuniform mutation on the performance of the GA is examined. Not only binary representation but also floating-point representation are used to express the design gene in the GA. Fuzzy theory is applied in the GA to handle the uncertainty of the constraint conditions. Two ways of solving fuzzy optimization are investigated in order to obtain a fuzzy solution and a crisp solution. Received: October 2, 2000 / Accepted: November 30, 2000     

多目标遗传算法在水面船舶快速性优化设计中的应用

在船舶设计中,船、机、桨的匹配问题一直是设计人员最关注的问题之一.快速性良好的船舶应使得船、主机和螺旋桨之间的性能综合匹配.通过采用改进的非支配解排序的多目标遗传算法,讨论了船舶概念设计阶段快速性优化问题.以推进系统综合效率和排水量为优化目标,考虑了混合变量的多目标优化问题.文中给出了载重量为35000t油船的快速性优化设计例子.结果表明,多目标遗传算法能够快捷搜索到全局最优解.     

The RHSA strategy for the allocation of outbound containers based on the hybrid genetic algorithm

Secure storage yard is one of the optimal core goals of container transportation;thus,making the necessary storage arrangements has become the most crucial part of the container terminal management systems（CTMS）.This paper investigates a random hybrid stacking algorithm（RHSA） for outbound containers that randomly enter the yard.In the first stage of RHSA,the distribution among blocks was analyzed with respect to the utilization ratio.In the second stage,the optimization of bay configuration was carried out by using the hybrid genetic algorithm.Moreover,an experiment was performed to test the RHSA.The results show that the explored algorithm is useful to increase the efficiency.     

多学科设计优化:载人潜水器设计的一种新工具

多学科优化作为一种新的设计方法,已经成功地应用在很多领域,如飞机制造,太空船,汽车制造等.传统的载人潜水器设计并不是一种最优的设计方法,并且在载人潜水器的设计过程中所要涉及多种技术学科.将多学科优化方法引进载人潜水器的设计,从而可以实现真正的设计优化.本文介绍了多学科优化的基本理论和方法,整体构架,并介绍了探索设计空间的算法.在对多学科优化设计方法理解的基础上,提出了在载人潜水器设计中如何应用的初步考虑.     

一种适用于船舶时域运动快速计算的混合方法

在时域内建立Rankine源法和时域Green函数法互相匹配的数学模型,控制面上的解既满足内部自由面条件,又满足远方辐射条件。由匹配数学模型可知只有控制面涉及到时域Green函数且与主尺度满足比列关系,因此不需每次都制表插值,实现了时域内船舶运动快速计算。将文中方法应用于零航速船舶瞬时运动数值计算,结果表明该方法具有良好的精确性、稳定性、高效性和普适性。     

A new regulation for the European public transport

Authority intervention in the public transport sector has a long history and has led to a growing corps of legal texts in European countries. These texts are often divergent, if not incompatible. This was no problem until the rather recent internationalization of the sector. With this internationalization, the European Commission decided to address this issue. This chapter describes what has led to the appearance of this new Regulation and the main steps on the 10-year long road that led to the adoption of the new Regulation. The chapter also formulates some comments on the results reached.     

基于改进遗传算法的双体无人艇性能优化分析

基于并行策略遗传算法对双体无人艇性能进行综合优化分析.首先建立以快速性、操纵性、抗倾覆性和耐波性为目标函数的综合优化数学模型,并使用响应面拟合的方法建立了3种不同的阻力数据库,通过遗传算法对其进行优化分析选出一组最适合本文的阻力数据库.在此基础上选取5个设计变量作为敏感变量进行讨论,其中最为敏感的2个变量将进行并行策略...     

基于遗传算法的武器系统安全可靠性的优化分析

分析武器系统的安全可靠性与费用的关系，提出了一个两目标优化问题的数学模型。并用遗传算法对其求解，为进行武器系统的安全优化设计得出了基于费用的多个备选方案。遗传算法设计中采用了性别编码、保留Pareto最优解、共享函数的处理，很好地解决了此两目标优化问题。最后给出的应用实例，也充分说明了此方法的可行性。     

基于遗传算法随车起重机折叠臂架铰点位置优化

以中型随车起重机折叠臂架结构为研究对象,为了降低此结构中液压缸最大受力和液压油波动对整机性能的影响,依据工作装置的工作原理,建立铰点优化数学模型,以液压缸受力最小为优化目标,各个铰点间长度为设计变量,在MATLAB中采用遗传算法对折叠臂架铰点位置进行优化设计,从优化结果可以看出,液压缸最大受力值明显减小,同时在整个工作过程中受力曲线较优化前曲线趋势明显变缓,液压油波动情况减弱,对液压缸安全性、稳定性具有重要意义。     

Ports,external costs,and Northern Italian transport network design: effects for the planned transformation

Modern ports need to be inserted in an efficient network in order to exploit all their potential, positively affecting both the efficiency of the local markets and the external costs of the served industries. Moreover, the role of the ports within the whole supply chain is affected by the location and the organization of intermediate facilities—such as logistics parks or inland ports—that heavily influence both the effectiveness of the logistics corridors and the externalities generated by the transport industry. New and adequate infrastructures can then reduce congestions, pollution, and accidents smoothing the whole logistics chains. The proposed study aims at discussing the effects in terms of rail share of the different planned interventions that are aimed at increasing the rail capacity of the network under investigation. In order to achieve this goal, a network optimization model has been solved by the optimizer solver of a spreadsheet. Outcomes can be used in order to improve current transport policies that might foster a more efficient and less impacting hinterland transport solution.     

A new functional optimization method applied to the pitch distribution of a marine propeller

Based on Hilbert space theory, an infinite-dimensional optimization method to find the optimal pitch distribution of marine propellers was developed. Thereby, the three-dimensional effect of induced velocity could effectively be controlled in an optimal way; i.e., an investigation was carried out to learn whether the present method is applicable to the design of marine propellers, especially pitch distributions, by maximizing the propeller efficiency functional. In addition, with the help of Hilbert space theory, it was successfully shown that the optimization method developed has a unique mathematical solution. In this work, only the pitch distribution was optimized, while other parameters such as the camber and thickness of the trial propeller remained as in the original. With a numerical study, it is shown that the present optimization method gives an optimal pitch distribution, the open-water characteristic curve being superior to the original curve. Received: August 24, 2000 / Accepted: July 16, 2001     

The development of the TIGRIS XL model: A bottom-up approach to transport, land-use and the economy

The project appraisal method in the Netherlands distinguishes direct effects, indirect distribution effects and indirect generative effects. Transport models are generally available for calculating the benefits of transport projects to travellers as part of the direct effects. The TIGRIS XL model, a Land-Use and Transport Interaction model, adds indirect distribution effects for the housing and labour market, by modelling changes in the spatial distribution of jobs and residents. This paper describes the current TIGRIS XL model and how it can be applied in the evaluation of transport projects. It refers to work done with the TIGRIS XL model to improve the calculation of the direct benefits by applying the so-called ‘logsum’ method. Finally it discusses ideas on how to extend the TIGRIS XL model to address indirect generative effects as well.The current TIGRIS XL model, its integration with the National Model System (the standard tool for the Dutch government to analyse the effects on passenger transport) and basic design principles are the starting point of such an exploration. These design principles include:

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an emphasis on detail, both spatial as well as in socio-economic segments, to account for differences in the availability of choice alternatives and in choice behaviour, and to provide impacts by region and socio-economic group;

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the requirement that the relationships used rest on an empirical foundation.

The post-processing methods proposed on this paper for the calculation of the direct benefits and indirect generative effects are consistent with these design principles. To calculate the indirect generative effects, a post-processing module is proposed which transforms changes in travel times and land-use into agglomeration effects. These agglomeration effects combine several of the generative effects, like scale economies, an increasing variety of products, labour market matches and knowledge spill-over. The effects of changes in the agglomeration indicator on productivity can be estimated with existing data sources, as was demonstrated in the UK (Graham, 2005).     

基于节点电势法的舰船电力系统潮流计算方法

针对舰船电力系统中非线性负载尤其是异步电动机负载较多,且发电机组数量多、容量小,需考虑其功率分配关系等特点,提出基于节点电势法的潮流计算改进算法。利用此算法对一个8节点的典型舰船电力系统模型进行计算,并通过Matlab软件仿真予以验证。结果表明,该算法具有计算精度高、收敛速度快等特点。     

A numerical transport model for predicting the distributions of Cd, Cu, Ni, Pb and Zn in the southern North Sea: the sensitivity of model results to the uncertainties in the magnitudes of metal inputs

A new transport model for metals (named NOSTRADAMUS) has been developed to predict concentrations and distributions of Cd, Cu, Ni, Pb and Zn in the southern North Sea. NOSTRADAMUS is comprised of components for water, inorganic and organic suspended particulate matter transport; a primary production module contributes to the latter component. Metal exchange between dissolved (water) and total suspended particulate matter (inorganic + organic) phases is driven by distribution coefficients. Transport is based on an existent 2-D vertically integrated model, incorporating a 35 × 35 km grid. NOSTRADAMUS is largely driven by data obtained during the Natural Environment Research Council North Sea Project (NERC NSP). The sensitivity of model predictions to uncertainties in the magnitudes of metal inputs has been tested. Results are reported for a winter period (January 1989) when plankton production was low. Simulated ranges in concentrations in regions influenced by the largest inflows, i.e. the NE English coast and the Southern Bight, are similar to the ranges in the errors of the concentrations estimated at the northern and southern open sea boundaries of the model. Inclusion of uncertainties with respect to atmospheric (up to ± 54%) and riverine (± 30%) inputs makes little difference to the calculated concentrations of both dissolved and particulate fractions within the southern North Sea. When all the errors associated with the inputs are included there is good agreement between computed and observed concentrations, and that for dissolved and particulate Cd, Cu and Zn, and dissolved Ni and Pb, many of the observations fall within, or are close to, the range of values generated by the model. For particulate Pb, model simulations predict concentrations of the right order, but do not reproduce the large scatter in actual concentrations, with simulated concentrations showing a bias towards lower values compared to those observed. A factor which could have contributed to observed concentrations, and which is not included in the model, is considered to be a substantial benthic input of dissolved lead during this winter period, coupled to a rapid and extensive scavenging of the dissolved lead to particles. Significant reductions in riverine and aeolian inputs of total Cd and Cu of 70% and 50%, respectively, consistent with aims of North Sea Conferences, are predicted to lead to minor decreases (~ 10%) in water column concentrations of dissolved and particulate Cd and Cu, except near river sources, where maximum reductions of ~ 30–40% may occur.     

A simulation of the simple Mohring model to predict patronage and value of resources consumed for enhanced bus services

Choosing between the competing approaches to providing enhanced bus services requires the ability to predict the effects on patronage and overall benefits to society in terms of Value of Resources Consumed (VRC) of any proposed change. One common approach uses the Mohring model of 1972 and its successors to optimise one or more aspects of the supply of transit services given various level of demand. This paper simulates the operation of a simple circular bus route using the equations of a basic Mohring type model and a Decision Support System (DSS) to endogenise demand under the assumption that there is a fixed demand for travel but commuters can choose between the bus and private vehicle. The selected approach recognises that demand for a particular mode of travel is predicated on the speed of the vehicle in service which is itself determined by the demand for that vehicle (in this model or boarding and alighting time) rather than being determined exogenously. This creates an iterative feedback mechanism whereby changes to the attributes of the bus and car alter mode choice and the speed in service of the bus which, in turn, alters mode choice. The simulation is used to predict changes to patronage and VRC under scenarios regarding changes to the transport network (in terms of fares and running costs, frequency and spacing of bus stops) using parameters from both a Multinomial Logit (MNL) and a Mixed Multinomial Logit (MMNL). The results demonstrate that there are large differences in the size and, in some cases, direction of predicted changes to patronage, VRC and revenue, depending on whether the parameters of the MNL or MMNL model are used.     

Watergate village: A case study of a permit application for a marina submitted to the U.S. army corps of engineers

Abstract

Abstract This case study, prepared by an interdisciplinary group of several scientists and planners and a lawyer, reviews the handling by the decision process of an application to the Baltimore District Corps of Engineers for permission to construct a marina. The study determines that while the project in question may not present a significant environmental threat, the project when considered in conjunction with other pending projects on the same subtributary would contribute to boat congestion and degradation of water quality. Changes in the decision process are suggested which would facilitate consideration of the cumulative impacts from a series of coastal alterations.