In this paper, we are concerned about the short-term scheduling of industrial make-and-pack production processes. The planning problem consists in minimizing the production makespan while meeting given end-product dem...
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ISBN:
(纸本)9781457707391
In this paper, we are concerned about the short-term scheduling of industrial make-and-pack production processes. The planning problem consists in minimizing the production makespan while meeting given end-product demands. Sequence-dependent changeover times, multi-purpose storage units with finite capacities, quarantine times, batch splitting, partial equipment connectivity, material transfer times, and a large number of operations contribute to the complexity of the problem. Known MILP formulations cover all technological constraints of such production processes, but only small problem instances can be solved in reasonable CPU times. In this paper, we develop a heuristic in order to tackle large instances. Under this heuristic, groups of batches are scheduled iteratively using a novel MILP formulation;the assignment of the batches to the groups and the scheduling sequence of the groups are determined using a priority rule. We demonstrate the applicability by means of a real-world production process.
This paper presents a mixed-integer linear programming approach to solving the optimal fixed/switched capacitors allocation (OCA) problem in radial distribution systems with distributed generation. The use of a mixed-...
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ISBN:
(纸本)9781457718014
This paper presents a mixed-integer linear programming approach to solving the optimal fixed/switched capacitors allocation (OCA) problem in radial distribution systems with distributed generation. The use of a mixed-integerlinear formulation guarantees convergence to optimality using existing optimization software. The results of one test system and one real distribution system are presented in order to show the accuracy as well as the efficiency of the proposed solution technique.
This paper derives a mathematical structure for investment decisions of a profit-maximising and strategic producer in liberalised electricity markets. The paper assumes a Cournot producer in an energy market with noda...
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ISBN:
(纸本)9781457710018
This paper derives a mathematical structure for investment decisions of a profit-maximising and strategic producer in liberalised electricity markets. The paper assumes a Cournot producer in an energy market with nodal pricing regime. The Cournot producer is assumed to have revenue from selling energy to the pool. The investment problem of the strategic producer is modelled through a leader-follower game in applied mathematics. The leader is the strategic producer seeking the optimal mix of its investment technologies and the follower is a stochastic estimator. The stochastic estimator forecasts the reactions of other producers in the market in response to the investment decisions of the producer in question. The stochastic estimator takes the investment decisions of the producer and it calculates the stochastic prices. The mathematical structure is a stochastic linear bilevel programming problem. This problem is reformulated as a stochastic MILP problem which can be solved using the commercially available software packages. Finally, the developed mathematical structure is applied to a six-node example system to highlight the strengths of the whole approach.
Electron microscopes are important tools for material science research since they can reveal accurate images (down to the atomic level) for a wide range of specimens. Moreover, a sample can be visualized while thermal...
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ISBN:
(纸本)9781457710636
Electron microscopes are important tools for material science research since they can reveal accurate images (down to the atomic level) for a wide range of specimens. Moreover, a sample can be visualized while thermal processes are induced to the specimen. Such processes involve the contraction or the expansion of the specimen holder, and hence image movement. In current practice one has to wait until the image stabilizes and then analyze the sample. In this paper we propose a hierarchical control framework where at the lower levels we use local and independent PID controllers for adjusting the stage and the beam deflectors. These controllers are then coordinated by a supervisory controller such that maximum performance is achieved. The coordinating controller will solve a nonlinear optimization problem for linear stage models in the model-based predictive control (MPC) setting. Typically, this problem is NP hard and therefore difficult to solve. In this paper we propose to further improve the performance of the system by recasting the optimization problem into a mixed-integer linear programming (MILP) one. The advantage is that for MILP optimization problems solvers are available which guarantee to find the global optimum. Then the MILP solution can be used as good initial point when solving optimization problems for nonlinear stage models.
This paper presents a decision support system named the Tanker Operations Planning System (TOPS). It is a user-friendly software with an advanced routing and scheduling algorithm to automate and aid the operational de...
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This paper presents a decision support system named the Tanker Operations Planning System (TOPS). It is a user-friendly software with an advanced routing and scheduling algorithm to automate and aid the operational decision making process. It considers the key operations constraints faced by the tanker owners. The advanced routing and scheduling algorithm embedded in the decision engine uses heuristics to solve industrial scale problems under actual operating conditions. Besides, TOPS can easily generate the routing, scheduling, stowage plan and the financial reports, and it can process a large number of orders online as well. In addition, TOPS can be conveniently modified for evaluation purposes or to suit the preference of the tanker owners. In essence, TOPS is an effective optimization-based decision support system to assist the parcel tanker carriers to systematically and objectively plan vessel routes and schedules with the goal of maximizing profits and fleet utilization in a structured manner. Drawing from actual data provided by a tanker company operating in the Asia Pacific, our simulation results show that TOPS can generate a cost effective routing and scheduling plan of a large scale problem to within a practically acceptable time of around 10-20 minutes
Abstract In this paper we discuss dynamic traffic management of railway traffic networks at an operational level. We design a model predictive controller based on measurements of the actual train positions. The core o...
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Abstract In this paper we discuss dynamic traffic management of railway traffic networks at an operational level. We design a model predictive controller based on measurements of the actual train positions. The core of the model predictive control approach is the railway traffic model, for which a switching max-plus linear system is proposed. If the model is affine in the controls, the optimisation problem can be recast as a mixed-integer linear programming problem. To this end we present a permutation-based algorithm to model the rescheduling of trains running on the same track. We apply the algorithm to a simple railway traffic network simulation model and show a significant reduction of delays compared to the uncontrolled case.
作者:
H.-O.GüntherTU Berlin
H95Production Management10623 BerlinGermanyStraβe des Juni 135
Traditionally,a discrete time scale is chosen to model lot sizing and *** paper proposes a novel continuous time based model formulation,called block planning,for application in the beverage *** block planning approac...
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Traditionally,a discrete time scale is chosen to model lot sizing and *** paper proposes a novel continuous time based model formulation,called block planning,for application in the beverage *** block planning approach is compared with a classic discrete time based MILP model formulation for single stage capacitated lot sizing and *** a case study,the production of beverages at a leading European producer of fruit juice is *** beverage industry as well as other branches of the consumer goods industry faces an increased number of package forms,customized package prints and labels,and a variety of flavours and compositions of ingredients. Typically,combined bottling and packaging lines are established for each package form,*** bottles,carton boxes,and glass *** proposed model formulations determine the lot sizing and scheduling decisions by solving an MILP model under the objective of minimizing the *** is shown that the continuous time based model formulation is much more compact with respect to the number of decision variables and constraints.
This paper derives a mathematical structure for investment decisions of a profit-maximising and strategic producer in liberalised electricity markets. The paper assumes a Cournot producer in an energy market with noda...
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ISBN:
(纸本)9781457710001
This paper derives a mathematical structure for investment decisions of a profit-maximising and strategic producer in liberalised electricity markets. The paper assumes a Cournot producer in an energy market with nodal pricing regime. The Cournot producer is assumed to have revenue from selling energy to the pool. The investment problem of the strategic producer is modelled through a leader-follower game in applied mathematics. The leader is the strategic producer seeking the optimal mix of its investment technologies and the follower is a stochastic estimator. The stochastic estimator forecasts the reactions of other producers in the market in response to the investment decisions of the producer in question. The stochastic estimator takes the investment decisions of the producer and it calculates the stochastic prices. The mathematical structure is a stochastic linear bilevel programming problem. This problem is reformulated as a stochastic MILP problem which can be solved using the commercially available software packages. Finally, the developed mathematical structure is applied to a six-node example system to highlight the strengths of the whole approach.
This paper proposes a methodology that can be used to design plans for evacuating transit-dependent citizens during no-notice disasters. A mixed-integerlinear program is proposed to model the problem of finding optim...
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This paper proposes a methodology that can be used to design plans for evacuating transit-dependent citizens during no-notice disasters. A mixed-integerlinear program is proposed to model the problem of finding optimal evacuation routes. The objective of the problem is to minimize the total evacuation time and the number of casualties, simultaneously. A traffic simulation package is used to explicitly incorporate the traffic flow dynamics into our model in order to generate solutions which are consistent with the dynamics of traffic network. Due to the long running time of CPLEX, a Tabu search algorithm is designed that finds evacuation routes for transit vehicles. Computational experiments demonstrate that the solutions found are of high-quality. Numerical experiments are conducted using the transportation network of the city of Forth Worth, TX to illustrate the modeling procedure and solution approach. (C) 2010 Elsevier Ltd. All rights reserved.
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