Papers by douglas miranda
Exacta, 2022
Este trabalho propõem um modelo de simulação para um conjunto de cruzamentos semaforizados de uma... more Este trabalho propõem um modelo de simulação para um conjunto de cruzamentos semaforizados de uma área localizada na região central de Uberaba-MG, com o objetivo de determinar valores para os tempos dos semáforos que permitam melhorar o fluxo de veículos. Para isto, descreve-se a dinâmica de funcionamento do sistema real, de modo a identificar as regras e comportamentos a serem incluídos no modelo de simulação, implementado via software Arena. Após a validação do modelo, realizou-se uma série de experimentos comparando diferentes cenários, incluindo experimentos fatorais; seguido por experimentos de otimização dos valores de tempo dos semáforos. O estudo de caso mostra que o tempo atual dos semáforos pode ser alterado de forma a permitir uma melhora de desempenho de até 24%; também se verifica que o Arena pode ser utilizado para a modelagem adequada de múltiplas vias, e que é possível ter uma solução prática, utilizável no mundo real.
A metaheuristic for the rural school bus routing problem with bell adjustment
Expert Systems with Applications, 2021
Abstract This paper addresses the school bus routing problem with bell adjustments. This problem ... more Abstract This paper addresses the school bus routing problem with bell adjustments. This problem extends the traditional school bus routing problem by having the school working times as decision variables instead of input data. Adjusting schools working times (bell adjustment) increases managerial flexibility to lower transportation costs. On the other hand, this comes at the price of having to deal with more complex solution design and greater computational complexity, as underlaid by the scarce literature on the theme. Here we propose different bell adjustment strategies for a rural variant of the problem which has particular importance both economically and socially for developing countries that usually have schooling with multiple shifts and budget restrictions. The memetic algorithm combines an iterated local search with specialized neighborhood structures arranged in a variable neighborhood descent strategy and enriched with a diversification scheme that relies on an elite set to solve large scale real instances. Different bell adjustment strategies are richly explained, tested, and analyzed thoroughly. The results of statistical analysis show significant cost savings for both cases with or without multi-loading. The new strategy achieved up to 9% savings and 2.55% savings on the consolidated results. Instances with a lower number of vehicles and a higher number of schools presented higher savings.
Goal: This research aims to investigate how to maximize the throughput and reduce the waiting tim... more Goal: This research aims to investigate how to maximize the throughput and reduce the waiting time for oncological patients of a radiotherapy process. Design / Methodology / Approach: A case study was conducted to develop a simulation model integrated with optimization techniques, including an expert system to support everyday decision making in the operation. Results: The experiments demonstrated that the approach was able to identify better configurations of the process, improving productivity without deteriorating quality. Results also considered the future acquisition of a new linear accelerator allowing the operation to plan its ramp up accordingly. Another result is the devised tool to allow the operation to run its own simulation studies. Limitations of the investigation: The results are valid for processes with similar characteristics of the one studied in the present paper, closing the scope at the treatment stage. Practical implications: This work demonstrates the possibil...
Applied Soft Computing, 2018
The version presented here may differ from the published version or, version of record, if you wi... more The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription.
Canadian Journal of Administrative Sciences / Revue Canadienne des Sciences de l'Administration, 2018
This paper considers a case study of dynamic job scheduling applied to a real accounting operatio... more This paper considers a case study of dynamic job scheduling applied to a real accounting operation. Tasks are assigned to agents over a time horizon minimizing the number of delays and overtime while maximizing the number of anticipated tasks. The solution respects a set of constraints such as agent skills, due time and precedence requirements. It also accounts for uncertainties by capturing changes in the environment such as new orders, changes in the agents' availability and unexpected problems while performing a task. The manager is given a chance to first simulate and then deploy corrective actions to mitigate the impact of changes in the environment. Two heuristics are developed and the results show a significant performance improvement in the operation.
Expert Systems with Applications, 2018
In this work we introduce the multi-loading school bus routing problem which extends the rural sc... more In this work we introduce the multi-loading school bus routing problem which extends the rural school bus routing problem with mixed loads by incorporating an innovative feature here referred to as multi-load. Whereas the mixed load variant allows students from different schools to ride the same bus at the same time, the multi-load model expands this definition by admitting students to be picked up and delivered simultaneously, regardless of their shift, commuting direction (going to or returning from school) or school, giving thus more flexibility to managers on lowering transportation costs. The multi-load feature has a great social and economic appeal, specially to developing countries that usually have double or triple shifts for schooling, and budget restrictions. The advantages and disadvantages of the new model are discussed and highlighted in our experiments which report the attained savings when compared with the mixed load approach for routing the students situated in rural areas of all 76 cities of the state of Espírito Santo, Brazil. To solve these large scale, real instances, different meta-heuristics were devised which combine an iterated local search with specialized neighborhood structures arranged in a variable neighborhood descent strategy enriched with a diversification scheme which relies on an elite set. The attained results demonstrate that the multi-loading approach can substantially reduce the solutions' cost.
Expert Systems with Applications, 2016
In real-world environments, the variability is always present and influences the level and cost s... more In real-world environments, the variability is always present and influences the level and cost service offered to customers. In this scenario, the present work develops a strategy to solve the Vehicle Routing Problem with Time Windows (VRPTW) in which the travel time among the customers is known only probabilistically and the vehicles are not allowed to start the service before the earliest time windows. The fact there is waiting time brings a challenge to the model because the arrival time distribution at a customer can be truncated, affecting the arrival time in the following customers. A new method is developed to estimate the vehicle arrival time at each customer and to estimate the vehicle"s probability to respect the customer"s time window. The metaheuristic based on Iterated Local Search finds the best route with minimal expected cost, and it guarantees that certain levels of service are met. A benchmark is used to evidence the superior performance and accuracy of the proposed method.
A practical method to calculate probabilities: illustrative example from the electronic industry business
Journal of Applied Statistics, 2016
ABSTRACT The real-life environment is made of probabilistic data by nature and the ability to mak... more ABSTRACT The real-life environment is made of probabilistic data by nature and the ability to make decisions based on probabilities is crucial in the business world. It is common to have a set of data and the need of calculating the probability of taking a value greater or less than a specific value. It is also common in many companies the unavailability of a statistical software or a specialized professional in statistics. The purpose of this paper is to present a practical and simple method to calculate probabilities from normal or non-normal distributed data set and illustrate it with an application from the electronic industry. The method does not demand statistical knowledge from the user; there is no need of normality assumptions, goodness test or transformations. The proposed method is easy to implement, robust and the experiments have evidenced its quality. The technique is validated with a large variety of instances and compared with the well-known Johnson system of distributions.
A atribuicao e o planejamento de rotas de veiculos e um problema crucial daadministracao de cadei... more A atribuicao e o planejamento de rotas de veiculos e um problema crucial daadministracao de cadeias de suprimentos. No ambiente real e comum encontrarproblemas que envolvam uma quantidade muito grande de clientes e queconsequentemente fogem do alcance de metodos exatos. Neste contexto, este trabalhovisa desenvolver metaheuristicas capazes de resolver algumas das mais importantesvariantes do problema de roteamento de veiculos (PRV): o PRV capacitado, o PRVcapacitado com maxima distância e o PRV com janelas de tempo. As metaheuristicasdesenvolvidas combinam a forca de estrategias bem sucedidas na literatura como TabuSearch, Guided Local Search e Adaptive Memory Procedure dentro de uma estruturaque utiliza o Iterated Local Search e o Variable Neighborhood Descent.O ambiente real tambem possui dados probabilisticos por natureza,como o tempo de viagem entre dois clientes. Isto faz com que um modelo de roteamentoque considere as incertezas envolvidas nestes dados seja mais apropriado. Nes...
OBS Para resolver um problema em que o vértice na origem é viável, escolher All-slack starting so... more OBS Para resolver um problema em que o vértice na origem é viável, escolher All-slack starting solution.
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Papers by douglas miranda