Encontrados 11 documentos, a visualizar página 1 de 2
A decomposition approach to the integrated vehicle-crew-rostering problem
Mesquita, Marta; Moz, Margarida; Paias, Ana; Pato, Margarida VazThe problem addressed in this paper is the integrated vehicle-crew-rostering problem (VCRP) aiming to define the schedules for the buses and the rosters for the drivers of a public transit company. The VCRP is described by a bi-objective mixed binary linear programming model with one objective function aggregating vehicle and crew scheduling costs and the other the rostering features. The VCRP is solved by a he...
Planning elective surgeries Analysis and comparison in a real case
Marques, Inês; Captivo, Maria Eugénia; Pato, Margarida VazThis work focus on hospital surgical suite optimization, mainly in the efficient use of the operating rooms when planning elective surgeries. We studied a real case in a hospital in Lisbon. An integer linear programming model was developed to weekly schedule elective surgeries for the hospital surgical suite. The model was tested with real data collected from the hospital records. Non-optimal solutions obtained...
Solving Public Transit Scheduling Problems
Mesquita, Marta; Moz, Margarida; Paias, Ana; Paixão, José; Pato, Margarida Vaz; Respício, AnaOperational planning within public transit companies has been extensively tackled but still remains a challenging area for operations research models and techniques. This phase of the planning process comprises vehicle scheduling, crew scheduling and rostering problems. In this paper, a new integer mathematical formulation to describe the integrated vehicle-crew-rostering problem is presented. The method propos...
A bi-objective hub-and-spoke approach for reconfiguring Web communities
Colaço, Susana; Pato, Margarida VazWeb communities in general grow naturally, thus creating unbalanced network structures where a few domains centralise most of the linkups. When one of them breaks down, a significant part of the community might be unable to communicate with the remaining domains. Such a situation is highly inconvenient, as in the case of wishing to pursue distribution policies within the community, or for marketing purposes. In...
Bi-objective Evolutionary Heuristics for Bus Drivers
Moz, Margarida; Respício, Ana; Pato, Margarida VazThe Bus Driver Rostering Problem refers to the assignment of drivers to the daily schedules of the company's buses, during a planning period of a given duration. The drivers' schedules must comply with legal and institutional rules, namely the Labour Law, labour agreements and the company's specific regulations. This paper presents a bi-objective model for the problem and two evolutionary heuristics differing a...
A Memetic Algorithm for a Bi-objective Bus Driver Rostering Problem
Respício, Ana; Moz, Margarida; Pato, Margarida VazThe Bus Driver Rostering Problem (DRP) consists of assigning bus drivers to daily duties during a planning period. The problem considers hard constraints imposed by institutional and legal requirements. Solutions should as much as possible satisfy soft constraints that qualify rosters according to either the company's or the drivers' interests. A bi-objective version of the DRP is considered and two models are ...
Solving a Bi-objective Nurse Rerostering Problem by Using a Utopic Pareto Genet...
Pato, Margarida Vaz; Moz, MargaridaNurse rerostering arises when at least one nurse announces that she will be unable to undertake the tasks previously assigned to her. The problem amounts to building a new roster that satisfies the hard constraints already met by the current one and, as much as possible, fulfils two groups of soft constraints which define the two objectives to be attained. A bi-objective genetic heuristic was designed on the ba...
Grasp and tabu search for redesigning web communities
Colaço, Susana; Pato, Margarida VazWeb topologies are commonly characterised by hierarchical structures and highly unbalanced compositions, as illustrated by the difference of centrality and connectivity as to their elements. The major interest of the problem addressed in this paper lies in restructuring web communities to reduce these initial disequilibria so as to democratise information access or even for the purpose of preserving contents di...
Elaboração de itinerários turísticos : Abordagem heurística de um caso real
Colaço, Susana Gueifão; Pato, Margarida VazThe problem of Tourist Routes Design involves defining circuits for a tourist wishing to enjoy a several days visit, in a given region following his particular interests. From an Operations Research standpoint, this problem can be framed as a vehicle routing problem with time windows. Once the issue has been analysed, mathematical formulations are drawn up. The methodology proposed is based on a breakdown of th...
A Comparison of Discrete and Continuous Neural Network Approaches to Solve the ...
Carrasco, Marco Paulo; Pato, Margarida VazThis study explores the application of neural network-based heuristics to the class/teacher timetabling problem (CTTP). The paper begins by presenting the basic CTTP characteristics in terms of hard and soft constraints and proposing a formulation for the energy function required to map the problem within the artificial neural network model. There follow two distinct approaches to simulating neural network evol...
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