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Real-world situations often result in optimization problems with conflicting objectives for which the search space is constrained by several factors. In particular, performing an effective solution brings quantifiable benefits to companies in charge of the waste collection in urban areas, which are currently investing time and effort to improve their services in terms of financial, social and environmental objectives, while bearing in mind labor factors. In this work, we model a real waste collection problem as a Capacitated Vehicle Routing Problem (CVRP) with two objectives: travel cost minimization and route balancing. To generate the best approximation of the Pareto front, we develop a multi-phase procedure. The first phase constructs solutions in a semi-greedy fashion; the second phase seeks to improve those solutions with a local search; and the third phase consists of a pairwise path-relinking search. Finally, we apply it to real-world data of the problem that motivated this work. [ABSTRACT FROM AUTHOR]

The aim of this work is to design a multiobjective model to explain the behavior among military expenditures (MEs), the human development index, and the global peace index in countries belonging to the North Atlantic Treaty Organization (NATO) for the study period 2008–2016. In order to solve this problem, different decision variables have been considered: health expenditure, education expenditure, Gross Domestic Product (GDP), collected taxes, public debt, and R&D costs, which are related to health, education, and economic sectors. To determine the relationships among decision variables making up the objective functions and model constraints, different panel data models were estimated. The obtained results show that the major part of the NATO countries present a behavior which differs from what is efficient. In this context, this work highlights the path to follow by each country, such as the implementation of public budget policies in the health and education sectors, and for collected taxes and public debt, to achieve efficient solutions. [ABSTRACT FROM AUTHOR]

Composite indicators are becoming more relevant for evaluating the performance of water companies from a holistic perspective. Some of them are related with economic aspects, and others focus on social and environmental features. Consequently, a multidimensional evaluation is necessary for handling the great amount of information provided by multiple single indicators of a different nature. This paper presents a two-phase approach to evaluate the sustainability of water companies. First, a partial composite indicator for each dimension (social, environmental, economic) is obtained using multi-criteria decision making (MCDM). Then, a global indicator is obtained, in terms of the values reached in the previous stage for every partial indicator, by means an optimization problem rooted in data envelopment analysis (DEA). Our proposal offers the possibility of analyzing the performance of each water company under each dimension that characterizes the concept of sustainability, as well as a joint assessment including all the dimensions, facilitating the decision-making process. We apply it to evaluate the sustainability of 163 Portuguese water companies. The results show the strengths and weaknesses of each unit and serve as a guideline to decision-makers on the aspects for improving the performance of water utilities. [ABSTRACT FROM AUTHOR]