This paper presents an integer programming model and a matheuristic for the physician rostering problem. Constraints related to physician's preferences, legal restrictions, hospital requirements and workload balance are investigated. Moreover, a comparison of physician and nurse rostering is analyzed to identify common constraints present in both problems. The lack of a mathematical model that could be applied in the studied problem motivated the development of a new formulation. Data and constraints of the proposed physician rostering problem were provided by Hospital de Clínicas de Porto Alegre (HCPA), Brazil. Due to the difficulty of solving large instances, a matheuristic which combines integer programming and heuristic techniques was proposed to approach the problem. Computational experiments were conducted employing commercial and open-source solvers. Results revealed that open-source solvers are a good alternative to solve small problems, while the proposed matheuristic generated near-optimal results within acceptable computation time employing larger instances.

This paper proposes a mathematical model to handle emergency service requests in electric power distribution utilities. Given available maintenance crews and their already assigned service orders, a mathematical model based on mixed integer linear programming is developed to solve the dynamic vehicle routing problem related to the task of deciding which maintenance crew will complete each pending emergency service request. One key aspect refers to the real-time constraint, what means that computational system must be able to handle a solution to the emergency work order dispatch problem with response times in the order of milliseconds or even microseconds. First, the problem definition is presented, followed by preliminary results that have shown how suitable can be the proposed definition when addressing the referred problem and also by using Google Earth plataform. Finally, conclusions point out the main contributions of this work.

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-828 - Resolução integRada de pRoblemas do planejamento do tRanspoRte público:foco na tabela de hoRáRios e no escalonamento de veículos com fRota heteRogênea* integrated resolution of public transport planning problems: focus on timetabling and vehicle scheduling with heterogeneous fleet ResumoNeste artigo, propõe-se um novo modelo de Programação Linear Inteira, baseado em uma rede tempo-espaço, que integra os problemas de geração da tabela de horários e o escalonamento de veícu-los com frota heterogênea. Um diferencial dessa abordagem consiste na consideração da demanda para a redefinição da tabela de horários e para o escalonamento dos veículos, fator raramente aplicado nos modelos de otimização do sistema de transporte. Foram utilizadas instâncias reais e aleatórias de grande porte. Os resultados indicam que o modelo pode contribuir para a otimização do planejamento do transporte público, tendo em vista que possibilita economias significativas no número de veículos escalonados. Além disso, como os intervalos de alteração da tabela de horários são bastante curtos, obtêm-se alterações sutis, modificando minimamente a rotina dos passageiros, o que possibilita a aplicação dessa abordagem ao contexto real.Palavras-chave: Escalonamento; Ônibus; Otimização.