Applications of Genetic Algorithm and Its Variants in Rail Vehicle Systems: A Bibliometric Analysis and Comprehensive Review

Railway systems are time-varying and complex systems with nonlinear behaviors that require effective optimization techniques to achieve optimal performance. Evolutionary algorithms methods have emerged as a popular optimization technique in recent years due to their ability to handle complex, multi-objective issues of such systems. In this context, genetic algorithm (GA) as one of the powerful optimization techniques has been extensively used in the railway sector, and applied to various problems such as scheduling, routing, forecasting, design, maintenance, and allocation. This paper presents a review of the applications of GAs and their variants in the railway domain together with bibliometric analysis. The paper covers highly cited and recent studies that have employed GAs in the railway sector and discuss the challenges and opportunities of using GAs in railway optimization problems. Meanwhile, the most popular hybrid GAs as the combination of GA and other evolutionary algorithms methods such as particle swarm optimization (PSO), ant colony optimization (ACO), neural network (NN), fuzzy-logic control, etc with their dedicated application in the railway domain are discussed too. More than 250 publications are listed and classified to provide a comprehensive analysis and road map for experts and researchers in the field helping them to identify research gaps and opportunities

OPTIMIZATION OF STATION LOCATIONS AND TRACK ALIGNMENTS FOR RAIL TRANSIT LINES

Designing urban rail transit systems is a complex problem, which involves the determination of station locations, track geometry, right-of-way type, and various other system characteristics. The existing studies overlook the complex interactions between railway alignments and station locations in a practical design process. This study proposes a comprehensive methodology that helps transit planners to concurrently optimize station locations and track alignments for an urban rail transit line. The modeling framework resolves the essential trade-off between an economically efficient system with low initial and operation cost and an effective system that provides convenient service for the public. The proposed method accounts for various geometric requirements and real-world design constraints for track alignment and stations plans. This method integrates a genetic algorithm (GA) for optimization with comprehensive evaluation of various important measures of effectiveness based on processing Geographical Information System (GIS) data. The base model designs the track alignment through a sequence of preset stations. Detailed assumptions and formulations are presented for geometric requirements, design constraints, and evaluation criteria. Three extensions of the base model are proposed. The first extension explicitly incorporates vehicle dynamics in the design of track alignments, with the objective of better balancing the initial construction cost with the operation and user costs recurring throughout the system's life cycle. In the second extension, an integrated optimization model of rail transit station locations and track alignment is formulated for situations in which the locations of major stations are not preset. The concurrent optimization model searches through additional decision variables for station locations and station types, estimate rail transit demand, and incorporates demand and station cost in the evaluation framework. The third extension considers the existing road network when selecting sections of the alignment. Special algorithms are developed to allow the optimized alignment to take advantage of links in an existing network for construction cost reduction, and to account for disturbances of roadway traffic at highway/rail crossings. Numerical results show that these extensions have significantly enhanced the applicability of the proposed optimization methodology in concurrently selecting rail transit station locations and generating track alignment

Euromech Colloquium 509: Vehicle Aerodynamics. External Aerodynamics of Railway Vehicles, Trucks, Buses and Cars - Proceedings

During the 509th Colloquium of the Euromech society, held from March 24th & 25th at TU Berlin, fifty leading researchers from all over europe discussed various topics affecting both road vehicle as well as railway vehicle aerodynamics, especially drag reduction (with road vehicles), cross wind stability (with trains) and wake analysis (with both). With the increasing service speed of modern high-speed railway traffic, aerodynamic aspects are gaining importance. The aerodynamic research topics comprise both pure performance improvements, such as the continuous lowering of aerodynamic drag for energy efficiency, as well as safety relevant topics, such as cross-wind stability. The latter topic was most recently brought to attention when a swiss narrow-gauge train overturned during the severe storm Kyrill in january 2007. The shape of the train head usually has largest influence on cross wind stability. Slipstream effects of passing trains cause aerodynamic loads on objects and passengers waiting at platforms. The strength of the slipstream is determined by both the boundary layer development along the length of the train and the wake developing behind the tail of the train. Since high-speed trains can be considered to be as smooth as technically possible, attention is drawn to the wake region. The wake of the train again is also one important factor for the total drag of a train. Due to the fact that trains are bidirectional, optimisation of the leading car of a train with respect to drag and cross wind performance while simultaneously minimising the wake of the train for drag and slipstream performance is a great challenge. Modern optimisation tools are used to aid this multi-parameter multi-constraint design optimisation in conjunction with both CFD and wind tunnel investigations. Since many of the aerodynamic effects in the railway sector are of similar importance to road vehicles, the aim of the colloquium is to bridge the application of shape optimisation principles between rail- and road vehicles. Particular topics to be addressed in the colloquium are: Drag, Energy consumption and emissions: Due to increase in energy cost, drag reduction has gained focus in the past years and attention will grow in the future. Pressure induced drag is of common importance for both rail- and road vehicles. The optimisation of head- and tail shape for road vehicles as well as for bi-directional vehicles (trains) is in the focus. Interference drag between adjacent components shall also be treated. Slipstream Effects: Are a safety issue for high-train operation (Prams sucked into track due to train-induced draught flows) when trains passing platforms at high speeds. For Road vehicles, the ride stability of overtaking cars is influenced by the wake of the leading trucks and busses. Common interest is the minimisation of wake effects for both rail and road vehicles. Cross-Wind Safety, Ride stability under strong winds: Both are safety issues for rail- and road vehicles. Aerodynamic forces shall be minimised (roll moment for trains and also yaw moment for road vehicles). Strategies for Vehicle shape optimisation (head, tail and roof shape) in order to minimise aerodynamic moments. Possibilities of Flow control. Optimisation strategies: Parametrisation, analyses (CFD), Optimisation tools and methods, Application to Drag, Cross-Wind, Ride stability and Snow issue

Intrinsic Properties of Composite Double Layer Grid Superstructures

This paper examined the opportunities of composite double-layer grid superstructures in short-to-medium span bridge decks. It was empirically shown here that a double-layer grid deck system in composite action with a thin layer of two−way reinforced concrete slab introduced several structural advantages over the conventional composite plate-girder superstructure system. These advantages included improved seismic performance, increased structural rigidity, reduced deck vibration, increased failure capacity, and so on. Optimally proportioned space grid superstructures were found to be less prone to progressive collapse, increasing structural reliability and resilience, while reducing the risk of sudden failure. Through a set of dynamic time-series experiments, considerable enhancement in load transfer efficiency in the transverse direction under dynamic truck loading was gained. Furthermore, the multi-objective generative optimization of the proposed spatial grid bridge (with integral variable depth) using evolutionary optimization methods was examined. Finally, comprehensive discussions were given on: (i) mechanical properties, such as fatigue behavior, corrosion, durability, and behavior in cold environments; (ii) health monitoring aspects, such as ease of inspection, maintenance, and access for the installation of remote monitoring devices; (iii) sustainability considerations, such as reduction of embodied Carbon and energy due to reduced material waste, along with ease of demolition, deconstruction and reuse after lifecycle design; and (iv) lean management aspects, such as support for industrialized construction and mass customization. It was concluded that the proposed spatial grid system shows promise for building essential and sustainable infrastructures of the future

Rail Cargo on the Lisbon-Madrid High-Speed Rail Line: an assessment of feasibility

Tese de doutoramento do Programa de Doutoramento em Sistemas de Transporte apresentada ao Departamento de Engenharia Civil da Faculdade de Ciências e Tecnologia da Universidade de CoimbraThis thesis presents an application to deal with the introduction of containerized cargo on the high-speed rail line operations between Lisbon and Madrid. The future rail line is a large, rigid and complex system with a long cycle of operation. Therefore, initial design needs to be carefully planned since once it’s installed it is very difficult and expensive to modify. In order to plan the infrastructure, its life cycle performance needs to be considered, given that the performance of the infrastructure depends not only on the initial project preparation and design but also on the maintenance and renewal decisions taken during the life cycle. In addition, in order to guarantee an optimal long-term result for the railway system, the effects of decisions taken should be methodically evaluated. Therefore, it is mandatory that all options (pre and post-operation) are evaluated in order to better serve demand and improve cargo investment efficiency. For different reasons until now, cargo was never a target revenue segment considered for high-speed rail lines development. The main reasons for this are the serious maintenance and operational constraints that occur when conventional freight-rail trains are ridded in a high-speed rail line, namely in terms of the track maintenance rehabilitation and safety for passengers. The current research aims to study the inclusion of ‘light rail-freight’ service on the Lisbon-Madrid high-speed rail connection in the investment evaluation through the use of dedicated rolling stock to deliver cargo. The expectation is to handle the extra capacity of the line derived from the passenger’s demand for introducing cargo services, aiming at a better efficiency for the investment. The analysis takes the passenger and cargo operations into consideration as well as all the impacts on the several potential stakeholders such as government, infrastructure manager, operator, other transport modes operators and society. This brings a multi-dimension into the decision process turning the analysis more complex but also more comprehensive. Stakeholders typically have different objectives and concerns. Their perspective and commitment to project varies according to these objectives and concerns. Thus, solutions need to find a compromising platform between those stakeholders in order to become implementable. As a result, a more comprehensive multi-stakeholder method is preferably used, instead a traditional cost-benefit approach. The feasibility of this method, called MATE – Multi-Attribute Tradespace Exploration, for dealing with this complex transportation issues and associated constraints is discussed and the result is positive, not only for the problem addressed but also for the recognition of its potential to be applicable to other transportation domains. If one takes into consideration that rail-cargo activity should integrate a rail-road facility in order to turn the service commercially viable, results show the ability of the investment to integrate cargo trains in the daily routine of the line evaluated.A presente tese apresenta uma aplicação metodológica que lida com a introdução de carga contentorizada na operação da linha ferroviária de alta-velocidade entre Lisboa e Madrid. A futura linha ferroviária é representada por um grande e complexo sistema de transporte com um longo ciclo de operações. O planeamento eficaz da infraestrutura considera o desempenho do seu ciclo de vida, dado que o desempenho da infraestrutura não depende apenas do projeto inicial mas também das decisões de manutenção e renovação tomadas durante o ciclo de vida da infraestrutura. Além disso, a fim de garantir um resultado ótimo para o sistema ferroviário implementado, estas decisões deverão ser tomadas e avaliadas de forma metódica. Desde modo, é obrigatório que todas as opções (pré e pós-operação) sejam avaliadas, de forma a servir eficazmente a procura de passageiros e melhorar a eficácia do investimento de carga. Por diferentes motivos, a introdução de carga em linhas de alta-velocidade não tem sido uma opção de investimento nos diferentes sistemas de alta-velocidade implementados. Os principais motivos centram-se com os custos de operação, manutenção e as restrições operacionais que decorrem da circulação destas composições, nomeadamente em termos de reabilitação da via e segurança para os passageiros. A presente investigação tem como objetivo a introdução de mercadorias ‘leves’ na ligação de alta-velocidade entre Lisboa e Madrid e a avaliação do investimento necessário para o transporte de carga com recurso a material circulante dedicado. A expectativa é utilizar o espaço deixado pela operação de passageiros, para a introdução dos serviços de carga, de forma a melhorar/otimizar a eficiência do investimento. A análise leva em consideração as operações de passageiros e carga, bem como os impactos sobre os potenciais grupos de interessados selecionados, tais como o Estado, o Gerente da Infraestrutura, operadores e a sociedade em geral, integrando-os numa análise muti-dimensional. Os grupos de interessados selecionados têm, por norma, diferentes objetivos e interesses em relação à avaliação que fazem do investimento em análise. A sua perspetiva e ação de compromisso variam em relação a estes objetivos e preocupações. Assim, as soluções necessitam de encontrar um ponto de compromisso entre as diferentes partes interessadas, de forma a tornarem-se exequíveis. Como resultado, é apresentado um método multi-decisor mais abrangente do que as tradicionais abordagens Custo-benefício. A viabilidade do método MATE - Multi-Attribute Tradespace Exploration, para lidar com questões relativas a sistemas de transporte complexos, é aqui discutida e os resultados demonstram a capacidade para lidar não só com o problema abordado mas também o reconhecimento para lidar com outros domínios de transporte. Os resultados consideram um investimento em instalações de apoio rodoferroviário (plataforma logísticas) de forma a tornar comercialmente viável o serviço de transporte de carga e demonstram a capacidade do investimento para integrar o serviço de carga na rotina diária da operação da linha Lisboa-Madrid.FCT - SFRH/BD/42861/200

Time Localization of Abrupt Changes in Cutting Process using Hilbert Huang Transform

Cutting process is extremely dynamical process influenced by different phenomena such as chip formation, dynamical responses and condition of machining system elements. Different phenomena in cutting zone have signatures in different frequency bands in signal acquired during process monitoring. The time localization of signal’s frequency content is very important. An emerging technique for simultaneous analysis of the signal in time and frequency domain that can be used for time localization of frequency is Hilbert Huang Transform (HHT). It is based on empirical mode decomposition (EMD) of the signal into intrinsic mode functions (IMFs) as simple oscillatory modes. IMFs obtained using EMD can be processed using Hilbert Transform and instantaneous frequency of the signal can be computed. This paper gives a methodology for time localization of cutting process stop during intermittent turning. Cutting process stop leads to abrupt changes in acquired signal correlated to certain frequency band. The frequency band related to abrupt changes is localized in time using HHT. The potentials and limitations of HHT application in machining process monitoring are shown

Arc routing problems: A review of the past, present, and future

[EN] Arc routing problems (ARPs) are defined and introduced. Following a brief history of developments in this area of research, different types of ARPs are described that are currently relevant for study. In addition, particular features of ARPs that are important from a theoretical or practical point of view are discussed. A section on applications describes some of the changes that have occurred from early applications of ARP models to the present day and points the way to emerging topics for study. A final section provides information on libraries and instance repositories for ARPs. The review concludes with some perspectives on future research developments and opportunities for emerging applicationsThis research was supported by the Ministerio de Economia y Competitividad and Fondo Europeo de Desarrollo Regional, Grant/Award Number: PGC2018-099428-B-I00. The Research Council of Norway, Grant/Award Numbers: 246825/O70 (DynamITe), 263031/O70 (AXIOM).Corberán, Á.; Eglese, R.; Hasle, G.; Plana, I.; Sanchís Llopis, JM. (2021). Arc routing problems: A review of the past, present, and future. Networks. 77(1):88-115. https://doi.org/10.1002/net.21965S8811577

A Value-based Approach for Municipal Asset Management

Asset management serves to schedule interventions to maximize the condition of municipal assets. However, municipalities face the daunting task of dealing with a wide variety of assets (civil infrastructure, facilities, buildings, vehicles, machinery and equipment) with a limited budget. There is a lack of an approach to optimize the scheduling of interventions across all types of municipal assets. There is also a disconnection between the effectiveness of the budget and its ability to upkeep the value of the assets as demanded by accounting and financial regulations. Previous attempts to handle multiple assets face problems in budget balancing given the dissimilar units of measurement of condition indicator for each asset type. This research proposes a value-based approach supported by deterioration and depreciation curves. Treatments are used to sustain or increase the value of all assets. A case study of the municipality of Kindersley is presented to showcases how the value-based approach is more financially-sustainable, yet cost-effective. The approach is flexible enough to accommodate all types of municipal assets, however for limitations of data the case study considers: street names, signs, hydrants, lighting, sidewalks, roads, sanitary pipes and water mains. An Excel platform with a special Add-in is used to host the database and performance curves and to define the optimization problem. An external solver is used to find the optimal solution. Results demonstrate a more stable long term progression for the value-based approach as compared to the condition-based. Meanwhile budget remain at very similar levels