A variety of objective criteria are used in optimizing the flexible manufacturing system set-up problem in the academic literature. The literature also provides evidence that the objective criteria used in academic st...
详细信息
A variety of objective criteria are used in optimizing the flexible manufacturing system set-up problem in the academic literature. The literature also provides evidence that the objective criteria used in academic studies are often the least important in practice and that inventory related costs are rarely considered as an objective criterion. This study compares the flexible manufacturing system set-up problem across a set of strategically selected objective criteria including an inventory cost criterion. The comparison is done over varying set-up costs to inventory carrying cost ratios and machine workloads. The study provides guidelines on the merits of using each objective criterion under different conditions. The models used in the study included large mixed integer programming problems and quadratic programming problems with continuous and binary variables present. The binary variables in the quadratic program give the problem a combinatorial nature. In order to circumvent the combinatorial nature of the problem, we have used a combination of generate-and-test and constraint propagation strategies to generate the feasible values of the binary variables at the constraint level and to propagate the feasible binary values into the models. Generate-and-test and constraint propagation strategies used in conjunction with mathematicalprogramming are shown to greatly simplify generating solutions to a family of problems that are otherwise considered intractable. (c) 2007 Elsevier Ltd. All rights reserved.
Inter-city high-speed passenger transport, mainly aviation and high-speed railway, has been increasing around the world, in accordance with economic development and penetration of high-speed transport technologies. Th...
详细信息
Inter-city high-speed passenger transport, mainly aviation and high-speed railway, has been increasing around the world, in accordance with economic development and penetration of high-speed transport technologies. The energy consumption over the lifetime of transport infrastructure and operation is a significant factor at the planning stage. In this paper, we present a superstructure modelling and optimization framework of inter-city high-speed transport systems, accounting energy consumption during infrastructure construction and during subsequent operation, to optimize connections between large population centers and between modes of transport. Energy consumption during infrastructure construction is obtained from investment cost using lifecycle assessment. The first two cases considered differences between infrastructure construction and lifetime operation while the second case narrowed the study scope. Sensitivity analysis in the third case compared impacts of both transport means on system design. Model results have implications for actual high-speed transport technology development and infrastructure layout. (C) 2016 Elsevier Ltd. All rights reserved.
Water system integration is an effective way to save freshwater and reduce wastewater in enterprises. Water system integration treats the water system in an enterprise as a whole and utilizes water resources more effe...
详细信息
Water system integration is an effective way to save freshwater and reduce wastewater in enterprises. Water system integration treats the water system in an enterprise as a whole and utilizes water resources more effectively by optimizing the water utilization network. In this study, water system integration was applied to a yeast enterprise. According to the characteristics of the water utilization processes in the yeast enterprise, the water utilization processes were classified as fixed-load, fixed-flow, no-output flow, and no-input flow processes. optimization schemes for the no-output flow and no-input flow processes were obtained through qualitative judgment. optimization schemes for the fixed-load and fixed-flow processes were obtained using a mathematicalprogramming method. Through the adjustment of the water utilization network, it was demonstrated 27% of freshwater consumption could be saved and 23% of the COD could be reduced. (C) 2015 Elsevier B.V. All rights reserved.
Due to the difficulty in defining accurate models to represent the physical phenomena in glass furnaces. a large number of studies consider the process as a black-box system. The systemic approach proposed in this pap...
详细信息
Due to the difficulty in defining accurate models to represent the physical phenomena in glass furnaces. a large number of studies consider the process as a black-box system. The systemic approach proposed in this paper relies on a decomposition of the furnace into two entities, i.e. the combustion chamber and the glass bath. Next, a reactor network structure is automatically designed to reproduce the hydrodynamic features in the considered zone. These computations are based on the minimization of the quadratic difference between the network output and Residence Time Distributions (RTDs) obtained through CFD simulations. The optimization results provide a network structure showing good agreement with the RTDs computed by CFD. In addition, they highlight, in both furnace zones. some useless volumes that do not participate to the global flow. These results stand as a good basis to extend the study to the computations of kinetics, energy or environmental criteria, which in turn may be optimized. (C) 2009 Elsevier B.V. All rights reserved.
Surrogate constraint relaxation was proposed in the 1960s as an alternative to the Lagrangian relaxation for solving difficult optimization problems. The duality gap in the surrogate relaxation is always as good as th...
详细信息
Surrogate constraint relaxation was proposed in the 1960s as an alternative to the Lagrangian relaxation for solving difficult optimization problems. The duality gap in the surrogate relaxation is always as good as the duality gap in the Lagrangian relaxation. Over the years researchers have proposed procedures to reduce the gap in the surrogate constraint. Our aim is to review models that close the surrogate duality gap. Five research streams that provide procedures with zero duality gap are identified and discussed. In each research stream, we will review major results, discuss limitations, and suggest possible future research opportunities. In addition, relationships between models if they exist, are also discussed. (c) 2013 Elsevier B.V. All rights reserved.
Scheduling and resource allocation problems are widespread in many areas of today's technology and management. Their different forms and structures appear in production, logistics, software engineering, computer n...
详细信息
ISBN:
(纸本)9783319754178;9783319754161
Scheduling and resource allocation problems are widespread in many areas of today's technology and management. Their different forms and structures appear in production, logistics, software engineering, computer networks, etc. In practice, however, classical scheduling problems with fixed structures and only standard constraints (precedence, disjoint etc.) are rare. Practical scheduling problems include also logical and non-linear constraints and use non-standard criteria of schedule evaluations. In many cases, decision makers are interested in the feasibility and/or optimality of a given schedule for specified conditions formulated as questions, for example, Is it possible.?, What is the minimum/ maximum.?, What if ..? etc. Thus there is a need to develop a programming framework that will facilitate the modeling and solving a variety of diverse scheduling problems. This paper proposes such a constraint-based framework for modeling and solving scheduling problems. It was built with the CLP (Constraint Logic programming) environment and supported with MP (mathematicalprogramming).
A very fast nongradient procedure for function optimization is described. The procedure is based on the ideas of Rosenbrock [1] and Swann [2]. These were modified and refined to obtain an algorithm which provides an o...
详细信息
In this paper we extend the ELSP model to allow for linearly changing demand rates over a fixed planning horizon. This extension of the ELSP research provides a model that can be used in coordinating the production an...
详细信息
In this paper we extend the ELSP model to allow for linearly changing demand rates over a fixed planning horizon. This extension of the ELSP research provides a model that can be used in coordinating the production and marketing planning activities in a firm. The model allows the user to evaluate the impact of changes in product demand on production costs and customer service. We solve the model using a standard nonlinear programming package (MINOS) and show through examples based on actual production data how the model can be used to support coordinated production and marketing planning.
暂无评论