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 ...
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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.
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 tend...
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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.
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 ext...
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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.
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 des...
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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.
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 unit...
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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.
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...
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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.
When timber is to be used in the form of furniture it must be dried. Green timber contains many times more water than wood and if it is placed indoors the water will slowly evaporate. When the fibre saturation point i...
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When timber is to be used in the form of furniture it must be dried. Green timber contains many times more water than wood and if it is placed indoors the water will slowly evaporate. When the fibre saturation point is reached the wooden parts start to shrink and the shape of the details will change. If the wood is dried before it is used for furniture parts this calamity is reduced because shrinking has occurred already in the drying kiln when the raw material was in the form of lumber. This drying process uses a lot of heat which is produced by electricity or by firing wood chips or oil in boilers. The cost for these energy sources varies during the season or, for electricity, also during the day. This paper describes how to optimize the use of energy in two drying kilns located at a small carpentry factory in the south of Sweden. Monitored values from the factory are used in order to describe the process in close detail. These values are then used as a basis for a mathematical model which is designed in the form of a mixedintegerlinear program. The method makes it possible to optimize the operating schemes for the two dryers. Copyright (C) 2000 John Wiley & Sons, Ltd.
This paper introduces an integrated dynamic optimization approach for nonrenewable energy (NRE) resources management under uncertainty. A hybrid inexact chance-constrained mixed-integerlinearprogramming (ICCMILP) me...
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This paper introduces an integrated dynamic optimization approach for nonrenewable energy (NRE) resources management under uncertainty. A hybrid inexact chance-constrained mixed-integerlinearprogramming (ICCMILP) method is proposed, with an objective of maximizing economic return under constraints of resources availability and environmental regulations. In its solution process, the ICCMILP is transformed into two deterministic submodels, which correspond to the upper and lower bounds for the desired objective function value. Interval solutions, which are feasible and stable in the given decision space, can then be obtained by solving the two submodels sequentially. Thus, decision alternatives can be generated by adjusting decision variable values within their solution intervals. The obtained solutions are useful for decision makers to optimally allocate limited NRE resources over time for acquiring maximized benefit. Meanwhile, regional air quality could be maintained to keep the communities from health damage. Results of a hypothetical case study indicate that reasonable solutions for dynamic planning of NRE resources allocation in a regional system have been obtained. A number of decision alternatives were generated based on the ICCMILP solutions as well as the projected applicable conditions. (C) 2000 Elsevier Science B.V. All rights reserved.
We consider linearprogramming (LP) models for metabolic networks in which alternate optima often arise, and need to be identified to allow for data interpretation or the effective design of follow-up experiments. A r...
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We consider linearprogramming (LP) models for metabolic networks in which alternate optima often arise, and need to be identified to allow for data interpretation or the effective design of follow-up experiments. A recursive mixed-integerlinearprogramming (MILP) algorithm is proposed for rigorously finding all alternate optima. The carbon trafficking alternatives of an Escherichia coli mutant lacking pyruvate kinase are analyzed with the proposed algorithm. The results are discussed in terms of using them as an input to isotopomer mapping matrix calculations in order to design C-13 NMR experiments for maximum contrast. (C) 2000 Elsevier Science Ltd. All rights reserved.
The problem considered in this paper deals with the short term scheduling of a two stage continuous process with intermediate storage tanks. The major scheduling decisions in this problem are: a) the assignment of ord...
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The problem considered in this paper deals with the short term scheduling of a two stage continuous process with intermediate storage tanks. The major scheduling decisions in this problem are: a) the assignment of orders to various storage tanks;b) the sequence of orders in each unit;c) the timing of various operations in different stages. The problem is highly combinatorial in nature. The major challenge is to develop strong integerprogramming formulations and to devise efficient solution techniques. An initial model is presented in the form of a disjunctive program which is later transformed to a mixed integer linear programming (MILP) problem. A number of example problems are solved which highlight the limitations of this model as the number of orders increases. A heuristic based on partial preordering is considered which solves industrial sized problems very quickly. The objective function values for the heuristic solutions are within 7% of the optimal values.
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