Search results for "Operations"
showing 10 items of 1692 documents
A network model for the short-term prediction of the evolution of cocaine consumption in Spain
2010
Cocaine consumption is a social problem with acute consequences and its dependency can be regarded as a health concern of social transmission. This fact leads us to develop the idea that its transmission dynamics can be studied using epidemiological mathematical models. Under this point of view, in this paper we propose a network model to study the short-term evolution of the cocaine consumer subpopulations. The model parameters are obtained from data source and from an analogue continuous model. Sensitivity of the model parameters is studied. The parameters are associated with prevention and treatment policies and the sensitivity study gives us information about which parameters have more …
Assessing eco-efficiency with directional distance functions
2012
Abstract Eco-efficiency is a matter of concern at present that is receiving increasing attention in political, academic and business circles. Broadly speaking, this concept refers to the ability to create more goods and services with less impact on the environment and less consumption of natural resources, thus involving both economic and also ecological issues. In this paper we propose the use of directional distance functions and Data Envelopment Analysis techniques to assess eco-efficiency. More specifically, we show how these functions can be used to compute a wide range of indicators representing different objectives regarding economic and ecological performance. This methodological ap…
Organizational Learning Capability and Job Satisfaction: an Empirical Assessment in the Ceramic Tile Industry
2009
Organizational learning capability has been considered an essential issue of an organization's effectiveness and potential to innovate and grow. Although its positive effects on organizations and employees are generally assumed, there is no empirical evidence of its positive association with employee attitudes such as job satisfaction. This paper aims to investigate the relationship between organizational learning capability and job satisfaction through the questionnaire responses of 157 employees from eight companies in the Spanish ceramic tile industry. Results suggest that organizational learning capability and job satisfaction are strongly linked.
Exploring working conditions as determinants of job satisfaction: an empirical test among Catalonia service workers
2011
Job satisfaction is particularly important in the service industries since it involves direct contact with customers and thus has a direct influence on company performance. This paper analyses the impact of 10 working conditions on job satisfaction by means of structural equation modeling in a representative stratified random sample of 1553 service sector employees in Catalonia, Spain. Significant effects in social aspects (recognition of a job well done and social support) were found, followed by psychological loads (emotional demands and job insecurity) and by task contents (development and meaning, and predictability). These variables explained 50% of the variance in job satisfaction.
Meeting the environmental challenge of port growth: A critical appraisal of the contingent valuation method and an application to Valencia Port, Spain
2012
In order to support effective policy-making, this research is aimed to emphasise the need of measuring the negative impact - or external costs - resulting from port growth. Considering the non-market nature of these external costs, a critical appraisal of the Contingent Valuation method is made paying special attention to the problem of hypothetical bias and the suitability of a willingness to accept (WTA) scenario for damage assessment. Finally, the results of a case study, conducted in Valencia (Spain), are presented with the intention of paving the way for future research in this specific context of port growth and negative externalities. In particular, results indicate that the average …
An evolutionary method for complex-process optimization
2010
10 páginas, 7 figuras, 7 tablas
Black box scatter search for general classes of binary optimization problems
2010
The purpose of this paper is to apply the scatter search methodology to general classes of binary problems. We focus on optimization problems for which the solutions are represented as binary vectors and that may or may not include constraints. Binary problems arise in a variety of settings, including engineering design and statistical mechanics (e.g., the spin glass problem). A distinction is made between two sets of general constraint types that are handled directly by the solver and other constraints that are addressed via penalty functions. In both cases, however, the heuristic treats the objective function evaluation as a black box. We perform computational experiments with four well-k…
On the Extension of the DIRECT Algorithm to Multiple Objectives
2020
AbstractDeterministic global optimization algorithms like Piyavskii–Shubert, direct, ego and many more, have a recognized standing, for problems with many local optima. Although many single objective optimization algorithms have been extended to multiple objectives, completely deterministic algorithms for nonlinear problems with guarantees of convergence to global Pareto optimality are still missing. For instance, deterministic algorithms usually make use of some form of scalarization, which may lead to incomplete representations of the Pareto optimal set. Thus, all global Pareto optima may not be obtained, especially in nonconvex cases. On the other hand, algorithms attempting to produce r…
LR-NIMBUS : an interactive algorithm for uncertain multiobjective optimization with lightly robust efficient solutions
2022
In this paper, we develop an interactive algorithm to support a decision maker to find a most preferred lightly robust efficient solution when solving uncertain multiobjective optimization problems. It extends the interactive NIMBUS method. The main idea underlying the designed algorithm, called LR-NIMBUS, is to ask the decision maker for a most acceptable (typical) scenario, find an efficient solution for this scenario satisfying the decision maker, and then apply the derived efficient solution to generate a lightly robust efficient solution. The preferences of the decision maker are incorporated through classifying the objective functions. A lightly robust efficient solution is generated …
Heuristic algorithms for a storage location assignment problem in a chaotic warehouse
2014
The extensive application of emerging technologies is revolutionizing warehouse management. These technologies facilitate working with complex and powerful warehouse management models in which products do not have assigned fixed locations (random storage). Random storage allows the utilization of the available space to be optimized. In this context, and motivated by a real problem, this article presents a model that looks for the optimal allocation of goods in order to maximize the storage space availability within the restrictions of the warehouse. For the proposed model a construction method, a local search algorithm and different metaheuristics have been developed. The introduced algorit…