Ship Routing with Pickup and Delivery for a Maritime Oil Transportation System: MIP Modeland Heuristics

This paper examines a ship routing problem with pickup and delivery and time windows for maritime oil transportation, motivated by the production and logistics activities of an oil company operating in the Brazilian coast. The transportation costs from offshore platforms to coastal terminals are an important issue in the search for operational excellence in the oil industry, involving operations that demand agile and effective decision support systems. This paper presents an optimization approach to address this problem, based on a mixed integer programming (MIP) model and a novel and exploratory application of two tailor-made MIP heuristics, based on relax-and-fix and time decomposition procedures. The model minimizes fuel costs of a heterogeneous fleet of oil tankers and costs related to freighting contracts. The model also considers company-specific constraints for offshore oil transportation. Computational experiments based on the mathematical models and the related MIP heuristics are presented for a set of real data provided by the company, which confirm the potential of optimization-based methods to find good solutions for problems of moderate sizes

Analysis of a Parallel Machine Scheduling Problem with Sequence Dependent Setup Times and Job Availability Intervals

In this study, we propose constraint programming (CP) model and logic-based Benders algorithms in order to make the best decisions for scheduling non-identical jobs with availability intervals and sequence dependent setup times on unrelated parallel machines in a fixed planning horizon. In this problem, each job has a profit, cost and must be assigned to at most one machine in such a way that total profit is maximized. In addition, the total cost has to be less than or equal to a budget level. Computational tests are performed on a real-life case study prepared in collaboration with the U.S. Army Corps of Engineers (USACE). Our initial investigations show that the pure CP model is very efficient in obtaining good quality feasible solutions but, fails to report the optimal solution for the majority of the problem instances. On the other hand, the two logic-based Benders decomposition algorithms are able to obtain near optimal solutions for 86 instances out of 90 examinees. For the remaining instances, they provide a feasible solution. Further investigations show the high quality of the solutions obtained by the pure CP model

O problema dos árbitros viajantes: complexidade, modelagem e algoritmos

Estudamos neste doutorado o problema dos árbitros viajantes (TUP, do inglês traveling umpire problem), que consiste em um problema de otimizacão baseado no problema real de alocacão de árbitros às partidas da Liga Profissional de Beisebol dos Estados Unidos. O TUP recebe como entrada um torneio round robin duplo e tem como objetivo atribuir árbitros ás partidas deste torneio minimizando a distância total viajada por eles durante toda a competicão e respeitando restricões que impõem que cada árbitro não apite jogos de um mesmo time frequentemente e apite ao menos um jogo na sede de cada time. Demonstramos que o TUP é um problema NP-completo, fechando esta questão em relacão à sua complexidade que ficou em aberto durante sete anos. Também introduzimos duas novas formulacões matemáticas e uma heurística relax-and-fix para este problema. As análises de resultados computacionais comprovam que as formulacões matemáticas e a heurística relax-and-fix produzem limitantes inferiores e superiores de excelente qualidade para o TUP, melhorando diversos resultados da literatura.Sociedad Argentina de Informática e Investigación Operativa (SADIO

O problema dos árbitros viajantes: complexidade, modelagem e algoritmos

Estudamos neste doutorado o problema dos árbitros viajantes (TUP, do inglês traveling umpire problem), que consiste em um problema de otimizacão baseado no problema real de alocacão de árbitros às partidas da Liga Profissional de Beisebol dos Estados Unidos. O TUP recebe como entrada um torneio round robin duplo e tem como objetivo atribuir árbitros ás partidas deste torneio minimizando a distância total viajada por eles durante toda a competicão e respeitando restricões que impõem que cada árbitro não apite jogos de um mesmo time frequentemente e apite ao menos um jogo na sede de cada time. Demonstramos que o TUP é um problema NP-completo, fechando esta questão em relacão à sua complexidade que ficou em aberto durante sete anos. Também introduzimos duas novas formulacões matemáticas e uma heurística relax-and-fix para este problema. As análises de resultados computacionais comprovam que as formulacões matemáticas e a heurística relax-and-fix produzem limitantes inferiores e superiores de excelente qualidade para o TUP, melhorando diversos resultados da literatura.Sociedad Argentina de Informática e Investigación Operativa (SADIO

O problema dos árbitros viajantes: complexidade, modelagem e algoritmos

Estudamos neste doutorado o problema dos árbitros viajantes (TUP, do inglês traveling umpire problem), que consiste em um problema de otimizacão baseado no problema real de alocacão de árbitros às partidas da Liga Profissional de Beisebol dos Estados Unidos. O TUP recebe como entrada um torneio round robin duplo e tem como objetivo atribuir árbitros ás partidas deste torneio minimizando a distância total viajada por eles durante toda a competicão e respeitando restricões que impõem que cada árbitro não apite jogos de um mesmo time frequentemente e apite ao menos um jogo na sede de cada time. Demonstramos que o TUP é um problema NP-completo, fechando esta questão em relacão à sua complexidade que ficou em aberto durante sete anos. Também introduzimos duas novas formulacões matemáticas e uma heurística relax-and-fix para este problema. As análises de resultados computacionais comprovam que as formulacões matemáticas e a heurística relax-and-fix produzem limitantes inferiores e superiores de excelente qualidade para o TUP, melhorando diversos resultados da literatura.Sociedad Argentina de Informática e Investigación Operativa (SADIO

A Constraint Programming Approach for the Team Orienteering Problem with Time Windows

The team orienteering problem with time windows (TOPTW) is a NP-hard combinatorial optimization problem. It has many real-world applications, for example, routing technicians and disaster relief routing. In the TOPTW, a set of locations is given. For each, the profit, service time and time window are known. A fleet of homogenous vehicles are available for visiting locations and collecting their associated profits. Each vehicle is constrained by a maximum tour duration. The problem is to plan a set of vehicle routes that begin and end at a depot, visit each location no more than once by incorporating time window constraints. The objective is to maximize the profit collected. In this study we discuss how to use constraint programming (CP) to formulate and solve TOPTW by applying interval variables, global constraints and domain filtering algorithms. We propose a CP model and two branching strategies for the TOPTW. The approach finds 119 of the best-known solutions for 304 TOPTW benchmark instances from the literature. Moreover, the proposed method finds one new best-known solution for TOPTW benchmark instances and proves the optimality of the best-known solutions for two additional instances

Operational Research: Methods and Applications

Throughout its history, Operational Research has evolved to include a variety of methods, models and algorithms that have been applied to a diverse and wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first aims to summarise the up-to-date knowledge and provide an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion. It should be used as a point of reference or first-port-of-call for a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order. The authors dedicate this paper to the 2023 Turkey/Syria earthquake victims. We sincerely hope that advances in OR will play a role towards minimising the pain and suffering caused by this and future catastrophes

A Novel Multi-View Table Tennis Umpiring Framework

This research investigates the development of a low-cost multi-view umpiring framework, as an alternative to the current expensive systems that are almost exclusively restricted to elite professional sports. Table tennis has been selected as the testbed because, while automating the process is challenging, it has many different complex match elements including the service, return and rallies, which are governed by a strict set of regulations. The focus is mainly on the rally element rather than the whole match. Ball detection and tracking in video frames are undertaken to determine reliably the ball position relative to key reference objects like the table surface and net, and the ball’s flight path is used to determine the rally’s status. While a low-cost option has benefits, it is technically challenging due to the limited number of cameras and generally low video resolution used. This thesis presents a portable multi-view umpiring framework that identifies each state change in a rally. It makes three significant contributions to knowledge: i) a reliable ball detection strategy that accurately detects the location of the ball in low-resolution sequences; ii) a novel framework for ball tracking using a multi-view system, and iii) a new state-machine based evaluation system for analysing table tennis rallies. In a series of ten different test scenarios, the system achieved an average of 94% system detection rate and 100% accurate decisions. A test sequence of duration 1 s can be processed in 8 s, leading to a delay of only 7 s, which is considered acceptable for practical purposes. This solution has the potential to reform the way matches are umpired, providing objectivity in resolving disputed decisions. It affords an economic technology for amateur players, while the multi-view facility is extendible to other relevant ball-based sports. Finally, the ball flight path analysis mechanism can be a valuable training tool for skills development

Improving Perception to Make Distant Connections Closer

One of the challenges for perceptually grounded accounts of high-level cognition is to explain how people make connections and draw inferences between situations that superficially have little in common. Evidence suggests that people draw these connections even without having explicit, verbalizable knowledge of their bases. Instead, the connections are based on sub-symbolic representations that are grounded in perception, action, and space. One reason why people are able to spontaneously see relations between situations that initially appear to be unrelated is that their eventual perceptions are not restricted to initial appearances. Training and strategic deployment allow our perceptual processes to deliver outputs that would have otherwise required abstract or formal reasoning. Even without people having any privileged access to the internal operations of perceptual modules, these modules can be systematically altered so as to better serve our high-level reasoning needs. Moreover, perceptually based processes can be altered in a number of ways to closely approximate formally sanctioned computations. To be concrete about mechanisms of perceptual change, we present 21 illustrations of ways in which we alter, adjust, and augment our perceptual systems with the intention of having them better satisfy our needs

Operational Research: Methods and Applications

Throughout its history, Operational Research has evolved to include a variety of methods, models and algorithms that have been applied to a diverse and wide range of contexts. This encyclopedic article consists of two main sections: methods and applications. The first aims to summarise the up-to-date knowledge and provide an overview of the state-of-the-art methods and key developments in the various subdomains of the field. The second offers a wide-ranging list of areas where Operational Research has been applied. The article is meant to be read in a nonlinear fashion. It should be used as a point of reference or first-port-of-call for a diverse pool of readers: academics, researchers, students, and practitioners. The entries within the methods and applications sections are presented in alphabetical order