This paper presents a heuristic approach based on genetic algorithm (GA) for solving large-size multi-stage multi-product scheduling problem (MMSP) in batch plant. The proposed approach is suitable for different sched...
详细信息
This paper presents a heuristic approach based on genetic algorithm (GA) for solving large-size multi-stage multi-product scheduling problem (MMSP) in batch plant. The proposed approach is suitable for different scheduling objectives, such as total process time, total flow time, etc. In the algorithm, solutions to the problem are represented by chromosomes that will be evolved by GA. A chromosome consists of order sequences corresponding to the processing stages. These order sequences are then assigned to processing units according to assignment strategies such as forward or backward assignment, active scheduling technique or similar technique, and some heuristic rules. All these measures greatly reduce unnecessary search space and increase the search speed. In addition, a penalty method for handling the constraints in the problem, e.g., the forbidden changeovers, is adopted, which avoids the infeasibility during the GA search and further greatly increases the search speed. (c) 2006 Elsevier Ltd. All rights reserved.
To attain the highest economic and energy saving characteristics of gas turbine cogeneration plants, it is necessary to rationally determine capacities and numbers of gas turbines and auxiliary equipment in considerat...
详细信息
ISBN:
(纸本)9780791847923
To attain the highest economic and energy saving characteristics of gas turbine cogeneration plants, it is necessary to rationally determine capacities and numbers of gas turbines and auxiliary equipment in consideration of their operational strategies corresponding to seasonal and hourly variations in energy demands. Some optimization approaches based on the mixed-integer linear programming (MILP) have been proposed to such configuration design problems of energy supply plants. However, with increases in the numbers of the equipment which must be considered as candidates as well as the periods which must be set for variations in energy demands, the optimal configuration design problems become too large-scale and complex to solve. The author has proposed a MILP decomposition approach to obtain quasi-optimal solutions of the optimal configuration design problems in reasonable computation times. However, this approach has been limited to the optimal configuration design problems where equipment capacities are treated continuously. In this paper, the MILP decomposition approach is extended to the optimal configuration design problems where equipment capacities are treated discretely. The effectiveness of this extended approach is investigated through a numerical study on a gas turbine cogeneration plant.
We consider the problem of planning and scheduling physical and chemical processes on a multi-product chemical batch production plant. Such a plant consists of several multi-purpose processing units and storage facili...
详细信息
ISBN:
(纸本)9781424415281
We consider the problem of planning and scheduling physical and chemical processes on a multi-product chemical batch production plant. Such a plant consists of several multi-purpose processing units and storage facilities of limited capacity. Given primary requirements for final products, the problem consists in generating an appropriate set of batches for each process and scheduling the processing of those batches on the processing units subject to different types of technological constraints. In the literature the short-term planning problem is generally modeled as a monolithic mixed-integerlinear program. Due to the combinatorial nature of the problem, those models generally cannot be used when dealing with problem instances of practical size. In this paper we propose a two-level approach which is based on a decomposition of the problem into a hatching and a batch scheduling problem. We formulate the hatching problem as a mixed-integerlinear program, which allows for considering the execution of processes on alternative processing units with unit-specific lower and upper bounds on the batch sizes. The batch scheduling problem can be solved using a specific method known from the literature. We report on computational results for a sample production process from the chemical engineering literature.
Rapid-deployment mobile ad-hoc networks (MANETs) are frequently characterized by common over-arching mission objectives which make it reasonable to expect some degree or cooperativeness on the part of their constituen...
详细信息
ISBN:
(纸本)9781424410422
Rapid-deployment mobile ad-hoc networks (MANETs) are frequently characterized by common over-arching mission objectives which make it reasonable to expect some degree or cooperativeness on the part of their constituent nodes. In this article we demonstrate new strategies to improve MANET communications, based on inter-node cooperation with respect to node mobility. We present our model for cooperative mobility, and use this cost-benefit framework to explore the impact of cooperation in MANETs where nodes are-to varying extents-willing to be moved for the common good. We develop a mixed-integer linear programming (MILP) formulation of the model, accurately capturing its objectives and constraints. The MILP model is evaluated through simulations and found to be very effective, albeit for small networks. To make the proposed technique scale to large networks we develop a new technique for converting a large global MILP into a sequence of smaller local MILP optimizations, and demonstrate that the resulting approach is scalable and succeeds at efficiently moving cooperative nodes in a manner which optimizes connection bit error rates.
As a useful tool for combinatorial optimisation over continuous and discrete variables, the mixed-integer linear programming (MILP) approach can address complex control and planning models providing high computational...
详细信息
ISBN:
(纸本)9781424412969
As a useful tool for combinatorial optimisation over continuous and discrete variables, the mixed-integer linear programming (MILP) approach can address complex control and planning models providing high computational efficiency as well as robust behavior. On power system planning, previous work using MILP employed conventional dc load flow model neglecting reactive power, power loss and transformer tap ratios. In this paper, a novel thyristor-controlled series compensator (TCSC) allocation model is proposed based on recently reported tine flow equations and basic linearisation rule of binary-continuous products. The objectives of the planning strategy are to improve system loadability by choosing proper locations and settings of devices. Simulation results are presented and discussed for IEEE 9- and 118-bus systems.
Planning in partially observable domains is a notoriously difficult problem. However, inmany real-world scenarios, planning can be simplified by decomposing the task into a hierarchy of smaller planning problems. Seve...
详细信息
ISBN:
(纸本)9780262195683
Planning in partially observable domains is a notoriously difficult problem. However, inmany real-world scenarios, planning can be simplified by decomposing the task into a hierarchy of smaller planning problems. Several approaches have been proposed to optimize a policy that decomposes according to a hierarchy specified a priori. In this paper, we investigate the problem of automatically discovering the hierarchy. More precisely, we frame the optimization of a hierarchical policy as a non-convex optimization problem that can be solved with general non-linear solvers, a mixed-integer non-linear approximation or a form of bounded hierarchical policy iteration. By encoding the hierarchical structure as variables of the optimization problem, we can automatically discover a hierarchy. Our method is flexible enough to allow any parts of the hierarchy to be specified based on prior knowledge while letting the optimization discover the unknown parts. It can also discover hierarchical policies, including recursive policies, that are more compact (potentially infinitely fewer parameters) and often easier to understand given the decomposition induced by the hierarchy.
This paper presents an optimization based algorithm to solve the weekly scheduling problem of a large-scale hydrothermal power system, formulated as a mixed-integer linear programming model (MILP). The main drawback o...
详细信息
This paper presents an optimization based algorithm to solve the weekly scheduling problem of a large-scale hydrothermal power system, formulated as a mixed-integer linear programming model (MILP). The main drawback of the MILP approach is the high computational burden required to solve large-size problems. The proposed algorithm tackles this problem by providing an initial feasible and integer solution, which enhances the search of the Branch and Bound (B&B) over the space of feasible solutions, reducing the resolution time. A detailed representation of thermal, pumped storage, and hydroelectric units is considered, taking into account the net head dependence of hydro plants by means of an under-relaxed iterative process. The presented algorithm has been applied to real-scale study cases, obtaining satisfactory results in computational time and optimality. (c) 2006 Elsevier Ltd. All rights reserved.
In this paper, the problem of finding the optimal topological configuration of a power transmission system is considered with the aim of providing system operators with a tool suited for congestion management. Network...
详细信息
In this paper, the problem of finding the optimal topological configuration of a power transmission system is considered with the aim of providing system operators with a tool suited for congestion management. Network reconfiguration looks particularly appealing since it allows transmission system operators to alleviate overloads by means of switching operations that may avoid costly generation or load curtailments. The techniques of corrective switching proposed in the 1980s are profitably employed to formulate the problem of network reconfiguration for the purpose of congestion management. The solution of the resulting large-scale mixed-integerprogramming problem is carried out both by a deterministic branch- and-bound algorithm included in the CPLEX optimization package and by a genetic algorithm. Tests were performed on a 33-bus CIGRE test system and on an actual 432-bus network of Italian origin. (c) 2005 Elsevier B.V. All rights reserved.
In this study we model a gene network as a continuous-time switching network. In this model, each gene has a binary state which indicates if the gene expresses or not. We propose a method to control a sequence of expr...
详细信息
In this study we model a gene network as a continuous-time switching network. In this model, each gene has a binary state which indicates if the gene expresses or not. We propose a method to control a sequence of expression patterns in the gene network model by adding another continuous-time switching network. By using propositional calculus, we will show that the control problem can be formulated as a mixed-integer linear programming problem with linear constraints. (c) 2005 Elsevier Ltd. All rights reserved.
Progression systems synchronize traffic signals to maximize the green band, so that vehicles entering the band at one end of the arterial can pass the other unimpeded. Although traffic control systems optimize other c...
详细信息
Progression systems synchronize traffic signals to maximize the green band, so that vehicles entering the band at one end of the arterial can pass the other unimpeded. Although traffic control systems optimize other criteria, such as travel time and traffic flow, synchronization remains a desirable feature as drivers are averse to frequent stops. This paper gives a short account of progression systems based on bandwidth maximization, including MAXBAND and MULTIBAND , which can be cast as mixed-integer linear programming problems. To this end, the paper offers a brief review of cutting-planes, before developing a Chvátal-Gomory-based cutting-plane algorithm for bandwidth maximization and reporting numerical results. The cutting planes proved to be effective in the first iterations, inducing a substantial reduction on the upper bound for the maximum green band, but became ineffective in the remaining iterations. This paper finalizes with a research agenda to develop fast, effective algorithms for real-time applications.
暂无评论