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Solving a real-life, large-scale energy management problem

JOURNAL OF SCHEDULING 2013年第6期16卷 567-583页

作者： Godskesen, Steffen Jensen, Thomas Sejr Kjeldsen, Niels Larsen, Rune Univ Southern Denmark Dept Math & Comp Sci DK-5230 Odense M Denmark DONG Energy AS DK-7000 Fredericia Denmark

This paper introduces a three-phase hybrid heuristic for a large-scale energy management and maintenance scheduling problem. The problem is to schedule maintenance periods and refueling amounts for nuclear power plants with a time horizon of up to five years, and handling a number of scenarios for future demand and prices. The goal is to minimize the expected total production cost. The first phase of the heuristic solves a constraint programming model of a simplified version of the problem, the second performs a local search, and the third handles overproduction in a greedy fashion. This work was initiated in the context of the ROADEF/EURO Challenge 2010. In the concluding phase of the competition, our team ranked second in the junior category and sixth overall. After correcting a small implementation bug in the program that was submitted for final evaluation, our solver ranks first in the overall results from the competition.

关键词： Maintenance scheduling constraint programming ROADEF/EURO Challenge 2010 Production planning Hybrid heuristics

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Less-Than-Truckload carrier collaboration problem: modeling framework and solution approach

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JOURNAL OF HEURISTICS 2013年第6期19卷 917-942页

作者： Nadarajah, Selvaprabu Bookbinder, James H. Carnegie Mellon Univ Tepper Sch Business Pittsburgh PA 15213 USA Univ Waterloo Dept Management Sci Waterloo ON N2L 3G1 Canada

Less-Than-Truckload (LTL) carriers generally serve geographical regions that are more localized than the inter-city line-hauls served by truckload carriers. That localization can lead to urban freight transportation routes that overlap. If trucks are traveling with less than full loads, there typically exist opportunities for carriers to collaborate over such routes. We introduce a two stage framework for LTL carrier collaboration. Our first stage involves collaboration between multiple carriers at the entrance to the city and can be formulated as a vehicle routing problem with time windows (VRPTW). We employ guided local search for solving this VRPTW. The second stage involves collaboration between carriers at transshipment facilities while executing their routes identified in phase one. For solving the second stage problem, we develop novel local search heuristics, one of which leverages integer programming to efficiently explore the union of neighborhoods defined by new problem-specific move operators. Our computational results indicate that integrating integer programming with local search results in at least an order of magnitude speed up in the second stage problem. We also perform sensitivity analysis to assess the benefits from collaboration. Our results indicate that distance savings of 7-15 % can be achieved by collaborating at the entrance to the city. Carriers involved in intra-city collaboration can further save 3-15 % in total distance traveled, and also reduce their overall route times.

关键词： LTL collaboration Vehicle routing constraint programming Integer programming Integrated methods

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Declarative approach to cyclic steady state space refinement: periodic process scheduling

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INTERNATIONAL JOURNAL OF ADVANCED MANUFACTURING TECHNOLOGY 2013年第1-4期67卷 137-155页

作者： Bocewicz, Grzegorz Banaszak, Zbigniew A. Koszalin Univ Technol Dept Elect & Comp Sci Koszalin Poland Warsaw Univ Technol Dept Business Informat Warsaw Poland

Problems of cyclic scheduling are usually observed in flexible manufacturing systems which produce multitype parts where the automated guided vehicle system plays the role of a material handling system, as well as in various other multimodal transportation systems where goods and/or passenger itinerary planning plays a pivotal role. The schedulability analysis of the processes executed in the so-called systems of concurrent cyclic processes (SCCPs) can be executed within a declarative modeling framework. Consequently, the considered SCCP scheduling problem can be seen as a constraint satisfaction problem. Such a representation provides a unified way for evaluating the performance of local cyclic processes as well as of multimodal processes supported by them. Here, the crucial issue is that of a control procedure (e.g., a set of dispatching rules), which would guarantee the cyclic behavior of the SCCP. In this context, we discuss the sufficient conditions guaranteeing the schedulability of both local and multimodal cyclic processes, and we propose a recursive approach in designing them.

关键词： Cyclic processes Declarative modeling constraint programming State space Periodicity Dispatching rules

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Modelling distributed network attacks with constraints

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INTERNATIONAL JOURNAL OF BIO-INSPIRED COMPUTATION 2013年第4期5卷 210-225页

作者： Salgueiro, Pedro Abreu, Salvador Univ Evora CENTRIA P-7000671 Evora Portugal Univ Evora Dept Informat P-7000671 Evora Portugal

NeMODe is a declarative system for computer network intrusion detection, providing a declarative domain specific language for describing network intrusion signatures which can span several network packets, by stating constraints over network packets, describing relations between several packets in a declarative and expressive way. It provides several back-end detection mechanisms, all based on a constraint programming framework, to perform the detection of the desired signatures. In this work, we demonstrate how to model and perform the detection of distributed network attacks using each of the detection mechanisms provided by NeMODe, based in Gecode, adaptive search and MiniSat to perform the detection of the specific intrusions. We also use the sliding network traffic window version of the adaptive search back-end detection mechanism to simulate live network traffic and evaluate the performance of the system in conditions near to real life networks.

关键词： constraint programming propagation-based solvers constraint-based local search CBLS Boolean satisfiability problems intrusion detection systems IDSs domain specific languages

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Balancing and scheduling of flexible mixed model assembly lines

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constraintS 2013年第3期18卷 434-469页

作者： Ozturk, Cemalettin Tunali, Semra Hnich, Brahim Ornek, M. Arslan Izmir Univ Econ Dept Ind Syst Engn Izmir Turkey Izmir Univ Econ Dept Business Adm Izmir Turkey Izmir Univ Econ Dept Comp Engn Izmir Turkey

Mixed model assembly line literature involves two problems: balancing and model sequencing. The general tendency in current studies is to deal with these problems in different time frames. However, in today's competitive market, the mixed model assembly line balancing problem has been turned into an operational problem. In this paper, we propose mixed integer programming (MIP) and constraint programming (CP) models which consider both balancing and model sequencing within the same formulation along with the optimal schedule of tasks at a station. Furthermore, we also compare the proposed exact models with decomposition schemes developed for solving different instances of varying sizes. This is the first paper in the literature which takes into account the network type precedence diagrams and limited buffer capacities between stations. Besides, it is the first study that CP method is applied to balancing and scheduling of mixed model assembly lines. Our empirical study shows that the CP approach outperforms the MIP approach as well as the decomposition schemes.

关键词： Mixed model assembly lines Balancing Sequencing Scheduling Mixed integer programming constraint programming Decomposition

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Fast and Near-Optimum Schedule Optimization for Large-Scale Projects

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JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT 2013年第9期139卷 1117-1124页

作者： Menesi, Wail Golzarpoor, Behrooz Hegazy, Tarek Univ Waterloo Civil & Environm Engn Dept Waterloo ON N2L 3G1 Canada Univ Waterloo Dept Management Sci Waterloo ON N2L 3G1 Canada

Real-life construction projects are large in size and are challenged by many constraints, including strict deadlines and resource limits. In this paper, constraint programming (CP) is used as an advanced mathematical technique that suits schedule optimization problems. A practical CP optimization model has been developed to resolve both deadline and resource constraints simultaneously in large-scale projects. The proposed CP model is much faster than metaheuristic techniques and provides a set of feasible project durations that do not violate resource limits. The paper compares the CP results with several case studies from the literature to prove the practicality and usefulness of the CP approach to both researchers and practitioners. The CP model of this paper could provide solutions within 6.5% deviation from optimum schedules for a large project of 2,000 activities within minutes of processing time. This paper thus contributes to introducing a superior optimization model that is suitable for large-size projects and helps to render schedule optimization a mainstream cost-saving function within commercial scheduling systems.

关键词： Construction management Scheduling Costs Optimization Construction management Scheduling constraint programming Time-cost tradeoff Resource constrained scheduling Schedule optimization Large-scale projects Cost and schedule

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Conflict-aware optimal scheduling of prioritised code clone refactoring

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IET SOFTWARE 2013年第3期7卷 167-186页

作者： Zibran, Minhaz Fahim Roy, Chanchal Kumar Univ Saskatchewan Dept Comp Sci Saskatoon SK S7N 5C9 Canada

Duplicated or similar source code, also known as code clones, are possible malicious 'code smells' that may need to be removed through refactoring to enhance maintainability. Among many potential refactoring opportunities, the choice and order of a set of refactoring activities may have distinguishable effect on the design/code quality measured in terms of software metrics. Moreover, there may be dependencies and conflicts among those refactorings of different priorities. Addressing all the conflicts, priorities and dependencies, a manual formulation of an optimal refactoring schedule is very expensive, if not impossible. Therefore an automated refactoring scheduler is necessary to 'maximise benefit and minimise refactoring effort'. However, the estimation of the efforts required to perform code clone refactoring is a challenging task. This study makes two contributions. First, the authors propose an effort model for the estimation of code clone refactoring efforts. Second, the authors propose a constraint programming (CP) approach for conflict-aware optimal scheduling of code clone refactoring. A qualitative evaluation of the effort model from the developers' perspective suggests that the model is complete and useful for code clone refactoring effort estimation. The authors also quantitatively compared their refactoring scheduler with other well-known scheduling techniques such as the genetic algorithm, greedy approaches and linear programming. The authors' empirical study suggests that the proposed CP-based approach outperforms other approaches they considered.

关键词： genetic algorithms linear programming scheduling software metrics conflict aware optimal scheduling prioritised code clone refactoring source code malicious code smell refactoring activity software metrics optimal refactoring schedule automated refactoring scheduler constraint programming qualitative evaluation code clone refactoring effort estimation genetic algorithm linear programming genetic algorithms linear programming scheduling software metrics conflict aware optimal scheduling prioritised code clone refactoring source code malicious code smell refactoring activity software metrics optimal refactoring schedule automated refactoring scheduler constraint programming qualitative evaluation code clone refactoring effort estimation genetic algorithm linear programming

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View-based propagation of decomposable constraints

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constraintS 2013年第4期18卷 579-608页

作者： Correia, Marco Barahona, Pedro FCT UNL CENTRIA Ctr Artificial Intelligence Dept Informat P-2829516 Caparica Portugal

constraints that may be obtained by composition from simpler constraints are present, in some way or another, in almost every constraint program. The decomposition of such constraints is a standard technique for obtaining an adequate propagation algorithm from a combination of propagators designed for simpler constraints. The decomposition approach is appealing in several ways. Firstly because creating a specific propagator for every constraint is clearly infeasible since the number of constraints is infinite. Secondly, because designing a propagation algorithm for complex constraints can be very challenging. Finally, reusing existing propagators allows to reduce the size of code to be developed and maintained. Traditionally, constraint solvers automatically decompose constraints into simpler ones using additional auxiliary variables and propagators, or expect the users to perform such decomposition themselves, eventually leading to the same propagation model. In this paper we explore views, an alternative way to create efficient propagators for such constraints in a modular, simple and correct way, which avoids the introduction of auxiliary variables and propagators.

关键词： constraint programming Propagation Views

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A constraint-based approach for the shift design personnel task scheduling problem with equity

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COMPUTERS & OPERATIONS RESEARCH 2013年第10期40卷 2450-2465页

作者： Lapegue, Tanguy Bellenguez-Morineau, Odile Prot, Damien LUNAM Univ Inst Rech Commun & Cybernet Nantes IRCCyN UMR CNRS 6597 Ecole Mines Nantes F-44307 Nantes 3 France

This paper presents an industrial problem which arises in a company specialized in drug evaluation and pharmacology research. The aim is to build employee timetables covering the demand given by a set of fixed tasks. The optimality criterion concerns the equity of the workload sharing. A solution to this problem is the assignment of all tasks whose resulting working shifts respect tasks requirements as well as legal and organizational constraints. Scheduling problems usually consider a fixed set of shifts which have to be assigned to a given number of employees whereas in our problem shifts are not fixed and are deduced from the task assignment. In the following, we refer to this problem as the shift-design personnel task scheduling problem with an equity criterion (SDPTSP-E), in reference to the shift minimization personnel task scheduling problem (SMPTSP). Even if the SDPTSP-E is related to several problems, none of them allow to grasp its full complexity. Consequently, we propose a dedicated method based on constraint programming. Several branching and exploration strategies are proposed and tested. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Personnel task scheduling problem Fixed job scheduling problem Task assignment Shift design Equity constraint programming

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k-Pattern Set Mining under constraints

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IEEE TRANSACTIONS ON KNOWLEDGE AND DATA ENGINEERING 2013年第2期25卷 402-418页

作者： Guns, Tias Nijssen, Siegfried De Raedt, Luc Katholieke Univ Leuven Dept Comp Sci B-3000 Louvain Belgium

We introduce the problem of k-pattern set mining, concerned with finding a set of k related patterns under constraints. This contrasts to regular pattern mining, where one searches for many individual patterns. The k-pattern set mining problem is a very general problem that can be instantiated to a wide variety of well-known mining tasks including concept-learning, rule-learning, redescription mining, conceptual clustering and tiling. To this end, we formulate a large number of constraints for use in k-pattern set mining, both at the local level, that is, on individual patterns, and on the global level, that is, on the overall pattern set. Building general solvers for the pattern set mining problem remains a challenge. Here, we investigate to what extent constraint programming (CP) can be used as a general solution strategy. We present a mapping of pattern set constraints to constraints currently available in CP. This allows us to investigate a large number of settings within a unified framework and to gain insight in the possibilities and limitations of these solvers. This is important as it allows us to create guidelines in how to model new problems successfully and how to model existing problems more efficiently. It also opens up the way for other solver technologies.

关键词： Data mining pattern set mining constraints constraint programming

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