Search results for "operations"
showing 10 items of 1692 documents
Comparing interactive evolutionary multiobjective optimization methods with an artificial decision maker
2021
AbstractSolving multiobjective optimization problems with interactive methods enables a decision maker with domain expertise to direct the search for the most preferred trade-offs with preference information and learn about the problem. There are different interactive methods, and it is important to compare them and find the best-suited one for solving the problem in question. Comparisons with real decision makers are expensive, and artificial decision makers (ADMs) have been proposed to simulate humans in basic testing before involving real decision makers. Existing ADMs only consider one type of preference information. In this paper, we propose ADM-II, which is tailored to assess several …
Introduction to Spreadsheet Modeling and Metaheuristics
2017
Models, as a simplified representation of reality, are used daily in an attempt to control or understand some aspects of a real system. Simplification of reality is the accepted view of the modeling process, which assumes that reality represents the absolute truth. Without getting too deep into a philosophical discourse, it is worth mentioning the notion of model-dependent realism, a phrase coined by physicists Stephen Hawkings and Leonard Molinow in their book The Grand Design. Model-dependent realism “is based on the idea that our brains interpret the input from our sensory organs by making a model of the world to aid in the decision-making process.” This implies that more than one model …
Model Co-creation from a Modeler’s Perspective: Lessons Learned from the Collaboration Between Ethnographers and Modelers
2018
This paper reports on the authors’ ongoing collaboration on model co-creation, a process that involves not only the reconciliation of methodologies (qualitative vs. quantitative), but also of epistemologies (empirical vs empirical/rationalist) and ontologies (observable referent vs. abstracted referent). The co-creation process has taken place over several months, from early 2017, both in person, teleconferencing and via email. The result was an ethnographic model of the refugee situation in Lesbos, Greece. The qualifier “ethnographic” means that the simulation’s purpose was to capture the problem situation described by ethnographers in a manner that resembles their observations, not to ans…
The Integration of the Supply Chain as a Dynamic Capability for Sustainability: The Case of an Innovative Organic Company
2018
Numerous research projects have demonstrated that a firm’s ability to integrate, build, and reconfigure internal and external competencies to adapt to changes in its environment is a key capability for its competitiveness. However, in the case of developing the capabilities needed to implement innovation, we have found that the ability to integrate knowledge into the supply chain is also crucial since it is an essential requirement for bringing in technological change and product innovation. The purpose of this chapter is to understand the role of supplier integration in the implementation of radical innovation. First, we propose a theoretical model to connect supplier integration as a dyna…
Best proximity point theorems for proximal cyclic contractions
2017
The purpose of this article is to compute a global minimizer of the function $$x\longrightarrow d(x, Tx)$$ , where T is a proximal cyclic contraction in the framework of a best proximally complete space, thereby ensuring the existence of an optimal approximate solution, called a best proximity point, to the equation $$Tx=x$$ when T is not necessarily a self-mapping.
Combined column-and-row-generation for the optimal communication spanning tree problem
2018
Abstract This paper considers the exact solution of the optimal communication spanning tree problem (OCSTP), which can be described as follows: Given an undirected graph with transportation costs on every edge and communication requirements for all pairs of vertices, the OCSTP seeks for a spanning tree that minimizes the sum of the communication costs between all pairs of vertices, where the communication cost of a pair of vertices is defined as their communication requirement multiplied by the transportation cost of the unique tree path that connects the two vertices. Two types of compact formulations for OCSTP were presented in the literature. The first one is a four-index model based on …
Ranking corporate sustainability: a flexible multidimensional approach based on linguistic variables
2017
Corporate sustainability implies a compromise between the present environmental, social, and economic needs of a firm's stakeholders and their future needs. Corporate sustainability is therefore a multidimensional concept. Nowadays, several independent rating agencies rate firms in terms of environmental, social, and governance (ESG) criteria. These ratings are usually used by main sustainability indices such as the Dow Jones Sustainability Index, FTSE4 Good, Stoxx Sustainability Index, or Euronext Vigeo Family to select companies to invest in. Only those firms performing better than the average of their sector are selected. However, although providing linguistic ratings about the performan…
How selection of collaborating partners impact on the green performance of global businesses? An empirical study of green sustainability
2020
In recent days, both collaboration and sustainability have become an integral part of many global supply chains to achieve business excellence. Although previous literature and actual practices confirmed the successful implementation of sustainability practices through supply chain collaborations, it is not clear how collaborating partners can support financial and environmental performance, and hence strengthen the partnership performance in the global supply chains. To address this practice-based research question, we test the theoretical underpinning of suppliers and logistics partners in relation to required skills selection. We capture the depth of interdependencies in collaborations f…
Learning automata-based solutions to the optimal web polling problem modelled as a nonlinear fractional knapsack problem
2011
We consider the problem of polling web pages as a strategy for monitoring the world wide web. The problem consists of repeatedly polling a selection of web pages so that changes that occur over time are detected. In particular, we consider the case where we are constrained to poll a maximum number of web pages per unit of time, and this constraint is typically dictated by the governing communication bandwidth, and by the speed limitations associated with the processing. Since only a fraction of the web pages can be polled within a given unit of time, the issue at stake is one of determining which web pages are to be polled, and we attempt to do it in a manner that maximizes the number of ch…
Heuristics for the min–max arc crossing problem in graphs
2018
Abstract In this paper, we study the visualization of complex structures in the context of automatic graph drawing. Constructing geometric representations of combinatorial structures, such as networks or graphs, is a difficult task that requires an expert system. The automatic generation of drawings of graphs finds many applications from software engineering to social media. The objective of graph drawing expert systems is to generate layouts that are easy to read and understand. This main objective is achieved by solving several optimization problems. In this paper we focus on the most important one: reducing the number of arc crossings in the graph. This hard optimization problem has been…