This paper presents a simulation model to be used for water supply planning by a metropolitan water utility, Water supply operations for a single, monthly time step are formulated as a mixedintegerlinear program (or...
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This paper presents a simulation model to be used for water supply planning by a metropolitan water utility, Water supply operations for a single, monthly time step are formulated as a mixedintegerlinear program (or more simply, LP). The LP is then embedded in a month-by-month simulation model, The LP is formulated using a priority-based objective function, The model has been used successfully by the Alameda County Water District (California) staff for its long-range, integrated planning. The model also shows that some of the inherent weaknesses of math programming in general and mixed integer linear programming in particular, can be overcome to build a successful model.
mixed integer linear programming models are presented to develop a schedule for the mining of precious metal from available deposits. Alternate formulations and branch-and-bound search strategies are discussed. LINGO ...
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mixed integer linear programming models are presented to develop a schedule for the mining of precious metal from available deposits. Alternate formulations and branch-and-bound search strategies are discussed. LINGO was used to build and solve the models. (C) 1999 Elsevier Science Ltd. All rights reserved.
In this paper, we propose an enumeration method to check link conflicts in the mapping of n-dimensional uniform dependence algorithms with arbitrary convex index sets into k-dimensianal processor arrays. Previous meth...
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In this paper, we propose an enumeration method to check link conflicts in the mapping of n-dimensional uniform dependence algorithms with arbitrary convex index sets into k-dimensianal processor arrays. Previous methods on checking the link conflicts had to examine either the whole index set or the I/O spaces whose size are O(N-2n) or O(Nn-1), respectively, where hr is the problem size of the n-dimensional uniform dependence algorithm. In our approach, checking the link conflicts is done by enumerating integer solutions of a mixedintegerlinear program. In order to enumerate integer solutions efficiently, a representation of the integer solutions is devised so that the size of the space enumerated is O((2N)(n-k)). Thus, our approach to checking link conflicts has better performance than previous methods, especially for larger k. For the special case k = n - 2, we show that link conflicts can he checked by solving two linear programs in one variable.
The scheduling of batch chemical processes has been the focus of a substantial amount of research, focused primarily on building schedules for processes which are assumed to operate in a deterministic manner. This wor...
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The scheduling of batch chemical processes has been the focus of a substantial amount of research, focused primarily on building schedules for processes which are assumed to operate in a deterministic manner. This work describes an approach to directly incorporate schedules into a simulator for the purposes of schedule validation and testing of rescheduling methodologies when stochastic events occur. Although other types of uncertainty could be considered within the framework, the deviations presented in this work are those which can be represented as processing time variations and equipment breakdowns. The framework, when used open-loop, is an effective tool for evaluating the expected performance and robustness of various scheduling strategies. Two scheduling tools are compared, one which uses the uniform time discretized model and the other uses a non uniform discretization of time. In addition, user written logic has been incorporated into the simulator which allows the performance of various rescheduling techniques to be compared and evaluated prior to implementation in a processing facility. Numerical results of Monte Carlo simulation studies for both uses of the framework are presented. (C) 1999 Elsevier Science Ltd. All rights reserved.
The introduction of extended producer responsibility forces Original Equipment Manufacturers to set up a logistic network for take back, processing and recovery of discarded products. In this paper, we discuss a busin...
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The introduction of extended producer responsibility forces Original Equipment Manufacturers to set up a logistic network for take back, processing and recovery of discarded products. In this paper, we discuss a business case study carried out at Oce, a copier firm in Venlo (NL). It concerns the installment of remanufacturing processes. There is a choice from two locations in Venlo (NL) and one in Prague (Czech Republic), where assignments are subjected to managerial constraints. The study is meant to verify whether the strategic decision of Oce to move remanufacturing activities to the Czech Republic is also economically feasible. We limit ourselves to an optimisation of the HV02-machine network. We follow our general approach, in which we first determine how return products are processed (recovery strategy) and subsequently optimise the reverse logistic network design. We optimise on total operational costs over all possibilities and also compare three pregiven managerial solutions (= network designs) with a mixed integer linear programming model. Differences in economic costs appear to be very small, hence installing recovery activities in Prague for the HV02-machine must be well motivated from a strategic point of view. Moreover, we argue that besides cost minimisation, Oce should include performance indicators, such as JIT, reliability, in logistic optimisation to support its quality oriented business strategy. In addition, we discuss aspects regarding specific modelling elements in this case situation, the definition of cost functions, the possibility of optimising the forward and reverse logistic network and the use of LP- versus MILP-models in this kind of situations.
The evolution of both optimization methods and application fields in chemical engineering are presented in this paper. The study was carried out on three Escape Conferences, ESCAPE 1, ESCAPE 4 and ESCAPE 8. The use of...
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The evolution of both optimization methods and application fields in chemical engineering are presented in this paper. The study was carried out on three Escape Conferences, ESCAPE 1, ESCAPE 4 and ESCAPE 8. The use of classical mathematical programming approaches, like NLP, MILP and MINLP has reached a cruising speed, even when linear or Successive linearprogramming methods are less and less used. Due to the highly combinatorial nature of many problems, Simulated Annealing and Genetic Algorithms begin to compete with mathematical programming approaches. For optimal control purposes, Neural Networks appear to be an efficient tool. Continuous and batch process optimization and design always constitute a privileged application field of optimization procedures, but some recent classes of problems, like batch plant scheduling, thermodynamics, kinetics, molecular modeling and aided mixture design appear to emerge as new application fields.
In the present paper a mixed integer linear programming (MILP) formulation for a chromatographic separation process is described. What in this case makes the paper especially interesting, is the fact that hardly any m...
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In the present paper a mixed integer linear programming (MILP) formulation for a chromatographic separation process is described. What in this case makes the paper especially interesting, is the fact that hardly any mathematical programming method has been described for this kind of separation system, although many formulations have been described for other kinds of separation systems, e.g. distillation. The objective is to formulate the process in a linear form and to optimize the production.
An optimization problem for designing a nonuniformly spaced, linear-phase FIR filter with minimal complexity is formulated and solved by mixed integer linear programming (MILP). Examples illustrate that the proposed m...
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An optimization problem for designing a nonuniformly spaced, linear-phase FIR filter with minimal complexity is formulated and solved by mixed integer linear programming (MILP). Examples illustrate that the proposed method is useful for designing a wide range of filter types and can outperform subset selection-based design methods.
The cyclotomic polynomial (CP) prefilter design problem is formulated as an optimization problem with linear objective functions by applying logarithms to the transfer function of the CP prefilter, This problem is the...
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The cyclotomic polynomial (CP) prefilter design problem is formulated as an optimization problem with linear objective functions by applying logarithms to the transfer function of the CP prefilter, This problem is then solved by mixed integer linear programming (MILP). Design examples demonstrate that this method leads to more efficient cascaded finite impulse response (FIR) prefilter-equalizers than existing methods.
The design of a chilled water plant involves selecting the size and type of chillers to be employed and determining the operating strategy. The types may include both gas engine and electric motor driven chillers. The...
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The design of a chilled water plant involves selecting the size and type of chillers to be employed and determining the operating strategy. The types may include both gas engine and electric motor driven chillers. The issues that have to be considered in the selection problem are to incorporate external and internal factors into the decision making. External factors may include the utility rate schedules, the cooling load profile, and the outdoor temperature profile. Internal factors may include the chiller performance characteristics, initial and maintenance costs, and the chiller(s) operating strategy.
A mathematical model representing the chilled water plant design problem is developed. The problem is approached as a mixed integer linear programming problem where non-linear chiller performance curves are transformed into linear constraints through the use of integer variables. The optimization task is to select the best cooling plant configuration and operating strategy to minimize life cycle cost.
A solution procedure is developed which decomposes the optimization problem to reduce extensive computation time. Two case studies are provided to investigate the implementation of the mathematical model.
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