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A branch and cut method for the degree-constrained minimum spanning tree problem

NETWORKS 2001年第2期37卷 74-83页

作者： Caccetta, L Hill, SP Sch Math & Stat Perth WA 6845 Australia

A problem of interest in network design is that of finding, in a given weighted graph, a minimum-weight spanning tree whose vertices satisfy specified degree restrictions. We present a branch and cut solution procedure for this NP-complete problem. Our algorithm is implemented and extensively tested. Computational results on 3150 random table problems ranging from 100 to 800 vertices are presented and discussed. (C) 2001 John Wiley & Sons, Inc.

关键词： branch and cut combinatorial optimization network design optimal trees mixed integer linear programming

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An algorithm for synthesis of large time-constrained heterogeneous adaptive systems

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ACM TRANSACTIONS ON DESIGN AUTOMATION OF ELECTRONIC SYSTEMS 2001年第2期6卷 207-225页

作者： Shenoy, N Choudhary, A Banerjee, P Northwestern Univ Evanston IL 60208 USA

Large time-constrained applications are highly computer-intensive and are often implemented as a complex organization of pipelined data parallel tasks on a pool of embedded processors, DSP processors, and FPGAs. The large number of design alternatives available at each task level, the application as a whole, and the special needs of the reconfigurable devices (such as the FPGA) make the manual synthesis of such systems very tedious. The automatic synthesis algorithm in this paper combines exact (MILP-based) and heuristic techniques to solve this problem, which basically involves (1) propagation of timing constraints;(2) pipelining the loops to meet throughput requirements;(3) resource selection and allocation, keeping the processing requirements and the timing constraints in view;(4) scheduling the resources across the tasks to ensure maximum utilization;and (5) hiding the reconfiguration delays of the FPGAs. While the use of MILP techniques helps in getting high-quality results, combining them with heuristics ensures acceptable synthesis times, striking a good balance between quality of results and synthesis time. Our experimental evaluation of the algorithm shows an average 40% in resource cost reduction (compared to manual synthesis) with synthesis times from minutes to as low as a few seconds in some cases.

关键词： delay/cost table hierarchical control data-flow graph list scheduling mixed integer linear programming pipelining reconfigurable computing time-constrained synthesis

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Branch and cut methods for network optimization

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MATHEMATICAL AND COMPUTER MODELLING 2001年第4-5期33卷 517-532页

作者： Caccetta, L Hill, SP Curtin Univ Technol Sch Math & Stat Perth WA 6845 Australia

Combinatorial optimization problems arising in network applications are usually computationally difficult. Typically, one needs to solve a large mixed integer linear programming problem. Over the past decade, the method of branch and cut has emerged as a powerful technique for solving such problems. In this paper, we focus on computationally difficult network optimization for problems, highlighting the effectiveness of branch and cut methods. (C) 2001 Elsevier Science Ltd. All rights reserved.

关键词： branch and cut cutting planes combinatorial optimization mixed integer linear programming

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Short-term scheduling and recipe optimization of blending processes

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COMPUTERS & CHEMICAL ENGINEERING 2001年第4-6期25卷 627-634页

作者： Glismann, K Gruhn, G Tech Univ Hamburg Dept Proc & Plant Engn D-21071 Hamburg Germany

The main objective of this paper is to develop an integrated approach to coordinate short-term scheduling of multi-product blending facilities with nonlinear recipe optimization. The proposed strategy is based on a hierarchical concept consisting of three business levels: Long-range planning, short-term scheduling and process control. Long-range planning is accomplished by solving a large-scale nonlinear recipe optimization problem (multi-blend problem). Resulting blending recipes and production volumes are provided as goals for the scheduling level. The scheduling problem is formulated as a mixed-integer linear program derived from a resource-task network representation. The scheduling model permits recipe changeovers in order to utilize an additional degree of freedom for optimization. By interpreting the solution of the scheduling problem, new constraints can be imposed on the previous multi-blend problem. Thus bottlenecks arising during scheduling are considered already on the topmost long-range planning level. Based on the outlined approach a commercial software system has been designed to optimize the operation of in-line blending and batch blending processes. The application of the strategy and software is demonstrated by a detailed case study. (C) 2001 Elsevier Science Ltd. All rights reserved.

关键词： blending short-term scheduling recipe optimization mixed integer linear programming

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An enhanced 0-1 mixed integer LP formulation for the traffic signal problem

An enhanced 0-1 mixed integer LP formulation for the traffic...

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International Conference on Intelligent Transportation

作者： Wei-Hua Lin Department of Systems and Industrial Engineering University of Arizona Tucson Tucson AZ USA

An enhanced 0-1 mixed integer linear programming formulation is proposed for the traffic signal optimization problem based on the cell transmission model. The formulation has several new features that are unavailable in other existing models. The formulation handles physical queues, the number of stops, fixed or dynamic cycle length and splits, and lost time. The unintended vehicle holding problem, common in many existing analytical models, is eliminated in the proposed formulation. The formulation can be used for developing strategies for adaptive traffic control systems. Since the formulation is exact, it can also be used as a benchmark for examining the convergence behavior of existing heuristic algorithms based on the genetic algorithm, fuzzy logic, neural network or other approaches. The formulation can be solved using standard mathematical programming optimizers. The number of 0-1 integers used in the formulation is equal to the total number of intersections multiplied by the length of the entire optimization period.

关键词： Traffic control mixed integer linear programming Vehicle dynamics Vehicles Analytical models Adaptive systems Programmable control Adaptive control Convergence Heuristic algorithms

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Optimal standing reserve utilisation using genetic algorithms

Optimal standing reserve utilisation using genetic algorithm...

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IEEE Winter Meeting Power Engineering Society

作者： F. Li X. Zhang R.W. Dunn Department of Electronic& Electrical Engineering University of Bath Bath UK

ISBN: (纸本)0780366727

This paper proposes a genetic algorithm (GA) based economic contracting strategy for standing reserve in a typical standing reserve market. The aim of the contracting procedure is to identify the standing reserve tenders to be contracted and the correct-contract order among the tender options received and scheduled reserve alternatives, to meet the reserve requirement at the lowest possible cost. The contract ordering is a simple problem when all options are rendering for a fixed period of time, however, it becomes troublesome with the presence of flexible contracts, i.e. with standing reserve only available for a partial service window. The proposed GA contracting strategy aims to address the complexity caused by flexible contracts. The results for a system with 16 fixed and flexible tender options are presented and compared with those of mixed integer linear programming (MILP) methods.

关键词： Genetic algorithms Contracts Power system security Power generation economics Economic forecasting Costs mixed integer linear programming Consumer electronics Frequency Load forecasting

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Automatic datapath tile placement and routing

Automatic datapath tile placement and routing

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Design, Automation and Test in Europe Conference and Exhibition

作者： T. Serdar C. Sechen University of Washington Seattle WA USA

ISBN: (纸本)0769509932

We report the very first fully automatic datapath tile layout flow. We subdivided the placement process into two steps: a global placement step using simulated annealing, and a new detailed placement step based on extensive modifications we made to the O-tree algorithm. The modifications have enabled the extended O-tree algorithm to handle the rectilinearly shaped transistor chains and gates common in datapath tile layout. We show that datapath tiles can be placed and routed automatically at the transistor level or at the mixed transistor/gate level, achieving results for the very first time that are competitive to those obtained manually by a skilled designer.

关键词： Tiles Routing Reflection Logic circuits Manuals Rails Geometry Fingers Libraries mixed integer linear programming

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Efficient synthesis of array intensive computations onto FPGA based accelerators

Efficient synthesis of array intensive computations onto FPG...

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International Conference on VLSI Design

作者： N. Shenoy P. Banerjee A. Choudhary M. Kandemir Electrical and Computer Engineering Northwestern University Evanston IL USA

ISBN: (纸本)0769508316

Array intensive computations are characterized by processing of large arrays stored in external memory in multiple loops. Synthesizing these computations onto FPGAs involves automatic translation of the behavioral description into state machines controlled by a clock such that the execution time of the program as a whole is the minimum and area requirement does not exceed a predefined limit. The synthesis algorithm also needs to efficiently sequence the array, accesses taking into account memory access requirements such as pipelining. In this paper we present two algorithms each with a specific emphasis to handle this synthesis problem. Our heuristic algorithm generates good solutions in a very short time (less than a second), while our mixed integer linear programming (MILP) based algorithm can generate optimal solution given sufficient time. Both try to minimize execution time and area. Our algorithms not only look at individual loops to exploit parallelism but also consider them together while deciding the clock. The overall execution time is minimized and not just the number of cycles or the cycle time. They also efficiently synthesize memory accesses to fully exploit the memory pipelining. We compare these two algorithms in terms of their relative strengths.

关键词： Field programmable gate arrays Acceleration Clocks Automatic control Parallel processing Flow graphs Data flow computing Pipeline processing Heuristic algorithms mixed integer linear programming

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A novel decomposition method for MILP and its application to optimal operation of a thermal storage system

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ENERGY CONVERSION AND MANAGEMENT 2000年第16期41卷 1781-1795页

作者： Yokoyama, R Ito, K Osaka Prefecture Univ Dept Energy Syst Engn Sakai Osaka 5998531 Japan

A novel decomposition method for solving large scale mixed integer linear programming (MILP) problems with block angular structure is proposed to conduct operational planning of energy supply systems with storage units rationally and efficiently. The method is composed of solving two types of problems repeatedly: one is a large scale MILP master problem with the values of part of the integer variables fixed from the results of the other;the other is a small scale MILP subproblem with the values of the simplex multipliers obtained from the results of the former. The method is applied to the operational planning of a heat supply system with cold and hot water storage tanks. The validity and effectiveness of the method is evaluated in terms of solution optimality and computation time. As a result, it turns out that the method is superior to the conventional branch and bound method with the depth-first or best-bound search, (C) 2000 Elsevier Science Ltd. All rights reserved.

关键词： energy storage operational planning optimization mixed integer linear programming block angular structure decomposition large scale problems

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linear programming for flood control in the Iowa and Des Moines rivers

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JOURNAL OF WATER RESOURCES PLANNING AND MANAGEMENT-ASCE 2000年第3期126卷 118-127页

作者： Needham, JT Watkins, DW Lund, JR Nanda, SK David Ford Consulting Engineers Sacramento CA 95816 USA Univ Calif Davis Dept Civil & Environm Engn Davis CA 95616 USA Michigan Technol Univ Dept Civil & Environm Engn Houghton MI 49931 USA USA Corps Engineers Washington DC 20310 USA Hydrol Engn Ctr Davis CA 95616 USA

This study addresses questions related to flood-control operating procedures followed by the U.S. Army Corps of Engineers, Rock Island District. Application is presented of a mixed integer linear programming model for a reservoir system analysis of three U.S. Army Corps of Engineers' projects on the Iowa and Des Moines rivers. A strategy for evaluating the value of coordinated reservoir operations is developed. Results of this study suggest that operating Coralville Reservoir, on the Iowa River, for flood control on the Mississippi River does not provide appreciable benefits and, therefore, an operation plan coordinating releases from Coralville Reservoir with the two reservoirs on the Des Moines River may be unnecessary. Damage-minimizing results were obtained by operating the three reservoirs independently for 8 of the 10 largest hood events on record. Also, a review of the operating procedures for the hood of 1993 illustrates how much damage could have been reduced if inflows could be predicted months in advance or if the existing operating rules were more averse to extreme flood events.

关键词： Reservoir-system Optimization Operation Models Flood control Des Moines Lobe Desmoinesian reservoirs Surgery Iowa linear programming rivers mixed integer linear programming Mississippi River

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