Scielo RSS <![CDATA[Pesquisa Operacional]]> http://www.scielo.br/rss.php?pid=0101-743820180002&lang=en vol. 38 num. 2 lang. en <![CDATA[SciELO Logo]]> http://www.scielo.br/img/en/fbpelogp.gif http://www.scielo.br <![CDATA[A GENERALIZED DECOMPOSITION ALGORITHM FOR REAL-TIME TRUCK ROUTING PROBLEMS]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-74382018000200173&lng=en&nrm=iso&tlng=en ABSTRACT This paper is based on a practical project jointly conducted by a major trucking company and a renowned operations research consulting firm. It studies a large-scale, real-time truckload pickup and delivery problem. A number of cost factors are carefully measured such as loaded/empty travel distance, travel time, crew labor, equipment rental or operational cost, and revenue for completing the movements. This paper proposes a generalized decomposition algorithm that is capable of considering sophisticated business rules. The goal is to recommend executable and efficient truck routing decisions to minimize operating costs. Numerical tests are conducted with operational data from J.B.HUNT. A fleet of 5,000 trucks is considered in this experiment. The test result not only shows significant cost savings but also demonstrates computational efficiency for real-time application. <![CDATA[SOLVING IRREGULAR STRIP PACKING PROBLEMS WITH FREE ROTATIONS USING SEPARATION LINES]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-74382018000200195&lng=en&nrm=iso&tlng=en ABSTRACT Solving nesting problems or irregular strip packing problems is to position polygons on a fixed width and unlimited length strip, obeying polygon integrity containment constraints and nonoverlapping constraints, in order to minimize the used length of the strip. To ensure non-overlapping, we use separation lines, i.e., straight lines that separate polygons. We present a nonlinear programming model that considers free rotations of the polygons and of the separation lines. This model uses a considerable smaller number of variables than the few other approaches proposed in the literature. We use the nonlinear programming solver IPOPT (an algorithm of interior points type), which is part of COIN-OR. Computational tests were run using established benchmark instances and the results were compared with the ones obtained with other methodologies in the literature that use free rotations. <![CDATA[SCALAR AND VECTOR GAMES IN THE EVALUATION OF SOCIAL AND ENVIRONMENTAL DISCLOSURE AND THEIR RELATIONSHIP WITH MARKET VALUE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-74382018000200215&lng=en&nrm=iso&tlng=en ABSTRACT This study evaluated the association of social, environmental and socio-environmental disclosure with the market value of Brazilian companies with high environmental impact based on the Game Theory. To perform the analysis, rankings were developed by using scalar and vector gaming techniques. After the construction of the rankings, the association between them was verified through Kendall’s correlation analysis. The findings indicate a positive association of social, environmental and socio-environmental disclosure with the market value of Brazilian companies with high environmental impact. In addition, there was an increase in the degree of association during the investigated periods. This result suggests that the market is increasingly demanding regarding the disclosure of this information, which indicates that the disclosure of these information can bring competitive advantages in relation to the market value. <![CDATA[METAHEURISTIC ANALYSIS APPLIED TO THE BERTH ALLOCATION PROBLEM: CASE STUDY IN A PORT CONTAINER TERMINAL]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-74382018000200247&lng=en&nrm=iso&tlng=en ABSTRACT The simulated annealing (SA) and genetic algorithm (GA) metaheuristics are comparatively applied to the berth allocation problem (BAP) of a port container terminal. By synthesizing the experimental studies of the BAP available in the literature, the two methods are compared when applied to the same case. For this purpose, six test problems are considered, where SA and GA are compared using four crossover operators. Once the optimal GA crossover operator is determined, computational tests are performed with the data obtained at the port terminal to compare the performance of the two metaheuristics. <![CDATA[SIMULATION OPTIMIZATION IN DOSING PROCESS CONTROL SYSTEM IN REAL TIME IN A FREE AND OPEN-SOURCE SOFTWARE]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-74382018000200273&lng=en&nrm=iso&tlng=en ABSTRACT The purpose of this work is to implement an on-line control system able to adjust the production in real time applying a simulation model with algorithmic optimization and data transfer for a programmable logic controller. The Solver tool of the Excel software was integrated into a simulation software used to find the optimal dosing of input aggregates in a Hot Mix Asphalt process. Tests were carried out in different scenarios; the results demonstrated that the proposed control was effective, leading to a possible improvement in the quality of the product, enabling it to be kept within the specifications desired for most of the time. Besides, the proposed solution appeared to be simple and accessible for small companies as it applies the Excel software and a free and open-source discrete event simulation software. <![CDATA[MWSTAT: A MODULATED WEB-BASED STATISTICAL SYSTEM]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-74382018000200291&lng=en&nrm=iso&tlng=en ABSTRACT In this paper we present the development of a modulated web based statistical system, hereafter MWStat, which shifts the statistical paradigm of analyzing data into a real time structure. The MWStat system is useful for both online storage data and questionnaires analysis, as well as to provide real time disposal of results from analysis related to several statistical methodologies in a customizable fashion. Overall, it can be seem as a useful technical solution that can be applied to a large range of statistical applications, which needs of a scheme of devolution of real time results, accessible to anyone with internet access. We display here the step-by-step instructions for implementing the system. The structure is accessible, built with an easily interpretable language and it can be strategically applied to online statistical applications. We rely on the relationship of several free languages, namely, PHP, R, MySQL database and an Apache HTTP server, and on the use of software tools such as phpMyAdmin. We expose three didactical examples of the MWStat system on institutional evaluation, statistical quality control and multivariate analysis. The methodology is also illustrated in a real example on institutional evaluation. A MWStat module was specifically built for providing a real time poll for teacher evaluation at the Federal University of São Carlos (Brazil). <![CDATA[MAPPING OF THE BRAZILIAN SCIENTIFIC PUBLICATION ON FACILITY LOCATION]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-74382018000200307&lng=en&nrm=iso&tlng=en ABSTRACT Mathematical models are relevant to indicate the optimal location of facilities and, consequently, help in the search for efficiency in the supply chain. Although facility location problems are consolidated in the Operational Research field, few publications are dedicated to investigate the profile of the academic production (the amount of paper published), aiming to direct new studies on the subject and propose models that solve the current challenges. Thus, this paper aims to present a scientometric analysis of the articles on facility location published in the Web of Science, in order to verify the profile of Brazilian scientific production. As result, approximately 2% of the papers have researchers affiliated to Brazilian institutions. The interest for the subject is recent, with emphasis on universities. Brazil maintains an intense international collaboration network, cooperating with 45 different countries, especially USA. Finally, there is opportunity for publications that include the environmental dimention to mathematical models and for expansion in company-university-government collaboration. <![CDATA[THE RANK REVERSAL PROBLEM IN MULTI-CRITERIA DECISION MAKING: A LITERATURE REVIEW]]> http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0101-74382018000200331&lng=en&nrm=iso&tlng=en ABSTRACT Despite the importance of multicriteria decision-making (MCDM) techniques for constructing effective decision models, there are many criticisms due to the occurrence of a problem called rank reversal. Nevertheless, there is a lack of a systematic literature review on this important subject which involves different methods. This study reviews the pertinent literature on rank reversal, based on 130 related articles published from 1980 to 2015 in international journals, which were gathered and analyzed according to the following perspectives: multicriteria technique, year and journal in which the papers were published, co-authorship network, rank reversal types, and research goal. Thus our survey provides recommendations for future research, besides useful information and knowledge regarding rank reversal in the MCDM field.