29 research outputs found

    Food emergency dispatching method based on optimized fireworks algorithm

    Get PDF
    In order to solve the problem of food emergency dispatching under emergencies, a food emergency dispatching method based on the optimal fireworks algorithm was proposed. The fitness function was used to measure the individual merits of fireworks, the tabu table was set to avoid the fireworks algorithm falling into the local optimal, and the tournament strategy was adopted as the iterative strategy of fireworks population. The goal of the fitness function is to maximize the satisfaction of demand points and minimize the vehicle travel time.In order to accurately predict the amount of food required at the point of demand, an infectious disease model (SEIR) was used.By comparing with the basic fireworks algorithm and genetic algorithm, the simulation results show that the proposed algorithm has higher computational efficiency and can be used in food emergency dispatching

    Analysing the police patrol routing problem : a review

    Get PDF
    Police patrol is a complex process. While on patrol, police officers must balance many intersecting responsibilities. Most notably, police must proactively patrol and prevent offenders from committing crimes but must also reactively respond to real-time incidents. Efficient patrol strategies are crucial to manage scarce police resources and minimize emergency response times. The objective of this review paper is to discuss solution methods that can be used to solve the so-called police patrol routing problem (PPRP). The starting point of the review is the existing literature on the dynamic vehicle routing problem (DVRP). A keyword search resulted in 30 articles that focus on the DVRP with a link to police. Although the articles refer to policing, there is no specific focus on the PPRP; hence, there is a knowledge gap. A diversity of approaches is put forward ranging from more convenient solution methods such as a (hybrid) Genetic Algorithm (GA), linear programming and routing policies, to more complex Markov Decision Processes and Online Stochastic Combinatorial Optimization. Given the objectives, characteristics, advantages and limitations, the (hybrid) GA, routing policies and local search seem the most valuable solution methods for solving the PPRP

    Dynamic vehicle routing problems: Three decades and counting

    Get PDF
    Since the late 70s, much research activity has taken place on the class of dynamic vehicle routing problems (DVRP), with the time period after year 2000 witnessing a real explosion in related papers. Our paper sheds more light into work in this area over more than 3 decades by developing a taxonomy of DVRP papers according to 11 criteria. These are (1) type of problem, (2) logistical context, (3) transportation mode, (4) objective function, (5) fleet size, (6) time constraints, (7) vehicle capacity constraints, (8) the ability to reject customers, (9) the nature of the dynamic element, (10) the nature of the stochasticity (if any), and (11) the solution method. We comment on technological vis-à-vis methodological advances for this class of problems and suggest directions for further research. The latter include alternative objective functions, vehicle speed as decision variable, more explicit linkages of methodology to technological advances and analysis of worst case or average case performance of heuristics.© 2015 Wiley Periodicals, Inc

    Online Optimisation of Casualty Processing in Major Incident Response

    Get PDF
    Recent emergency response operations to Mass Casualty Incidents (MCIs) have been criticised for a lack of coordination, implying that there is clear potential for response operations to be improved and for corresponding benefits in terms of the health and well-being of those affected by such incidents. In this thesis, the use of mathematical modelling, and in particular optimisation, is considered as a means with which to help improve the coordination of MCI response. Upon reviewing the nature of decision making in MCIs and other disaster response operations in practice, this work demonstrates through an in-depth review of the available academic literature that an important problem has yet to be modelled and solved using an optimisation methodology. This thesis involves the development of such a model, identifying an appropriate task scheduling formulation of the decision problem and a number of objective functions corresponding to the goals of the MCI response decision makers. Efficient solution methodologies are developed to allow for solutions to the model, and therefore to the MCI response operation, to be found in a timely manner. Following on from the development of the optimisation model, the dynamic and uncertain nature of the MCI response environment is considered in detail. Highlighting the lack of relevant research considering this important aspect of the problem, the optimisation model is extended to allow for its use in real-time. In order to allow for the utility of the model to be thoroughly examined, a complementary simulation is developed and an interface allowing for its communication with the optimisation model specified. Extensive computational experiments are reported, demonstrating both the danger of developing and applying optimisation models under a set of unrealistic assumptions, and the potential for the model developed in this work to deliver improvements in MCI response operations

    Online optimisation for ambulance routing in disaster response with partial or no information on victim conditions

    Get PDF
    In response to mass casualty incidents, medical aid must be provided to numerous victims synchronously under challenging circumstances including uncertainty about the condition of victims. Therefore, it is essential to have decision support tools which can generate fast solutions under uncertainty and utilise the available medical resources efficiently to provide victims with the needed treatments. We introduce an online optimisation problem for routing and scheduling of the ambulances under uncertainty about the triage levels and required treatment times of the victims in mass casualty incidents. Due to the lack of information in the initial emergency response phase, we assume that the triage level and treatment time of each victim can be disclosed online only once the condition of a victim is closely assessed by the medical team on one of the ambulances at the casualty location. We investigate this problem under two different scenarios with partial and no information about the conditions of victims. We follow the theoretical competitive analysis framework for online optimisation and prove the lower bounds on the competitive ratio of deterministic and randomised online solutions for both cases of partial and no prior information. Next, we introduce three novel online heuristics to solve this problem. We verify the quality of our online solutions against the offline optimal solutions that are provided under complete information on a comprehensive set of 1296 instances from the literature. Finally, we draw our conclusions in regard to the suitability of each of our solutions in various scenarios of information availability with different numbers of victims

    The dial-a-ride problem with electric vehicles and battery swapping stations

    Get PDF
    The Dial-a-Ride Problem (DARP) consists of designing vehicle routes and schedules for customers with special needs and/or disabilities. The DARP with Electric Vehicles and battery swapping stations (DARP-EV) concerns scheduling a fleet of EVs to serve a set of pre-specified transport requests during a certain planning horizon. In addition, EVs can be recharged by swapping their batteries with charged ones from any battery-swap stations. We propose three enhanced Evolutionary Variable Neighborhood Search (EVO-VNS) algorithms to solve the DARP-EV. Extensive computational experiments highlight the relevance of the problem and confirm the efficiency of the proposed EVO-VNS algorithms in producing high quality solutions

    A hybrid evolutionary algorithm for vehicle routing problem with stochastic demands

    Get PDF
    In this work we propose a hybrid dynamic programming evolutionary algorithm to solve the vehicle routing problem with stochastic demands, it is a well known NP-hard problem where uncertainty enhances the computational efforts required to obtain a feasible and near-optimal solution. We develop an evolutionary technique where a rollout dynamic programming algorithm is applied as local search method to improve the quality of solutions. Motivated by computational considerations, the rollout algorithm can be applied partially, so, this finds competitive solutions in large instances for which the global rollout dynamic programming strategy is time unfeasible.Resumen. En este trabajo se propone un algoritmo evolutivo hibrido que combina un m ́etodo de programación dinámica estocástica para resolver el problema de enrutamiento de vehículos con demandas estocásticas, este es un problema demostrado como NP-difícil donde la presencia de incertidumbre incrementa los requerimientos computacionales necesarios para obtener soluciones factibles y cercanas a la óptima. Así, para el algoritmo evolutivo desarrollado se aplico un algoritmo rollout de programación dinámica estocástica como operador de búsqueda local para mejorar la calidad de las soluciones. Motivado por requerimientos computacionales, el algoritmo de rollout puede ser aplicado parcialmente, con el objetivo de encontrar soluciones competitivas en instancias lo suficientemente grandes para las cuales la estrategía global no es aplicable por consumir una cantidad de tiempo no tolerable.Maestrí

    Optimization for Decision Making II

    Get PDF
    In the current context of the electronic governance of society, both administrations and citizens are demanding the greater participation of all the actors involved in the decision-making process relative to the governance of society. This book presents collective works published in the recent Special Issue (SI) entitled “Optimization for Decision Making II”. These works give an appropriate response to the new challenges raised, the decision-making process can be done by applying different methods and tools, as well as using different objectives. In real-life problems, the formulation of decision-making problems and the application of optimization techniques to support decisions are particularly complex and a wide range of optimization techniques and methodologies are used to minimize risks, improve quality in making decisions or, in general, to solve problems. In addition, a sensitivity or robustness analysis should be done to validate/analyze the influence of uncertainty regarding decision-making. This book brings together a collection of inter-/multi-disciplinary works applied to the optimization of decision making in a coherent manner
    corecore