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Short-term scheduling of multiple source pipelines with simultaneous injections and deliveries

COMPUTERS & OPERATIONS RESEARCH 2016年 73卷 27-42页

作者： Mostafaei, Hossein Castro, Pedro M. Ghaffari-Hadigheh, Alireza Azarbaijan Shahid Madani Univ Dept Appl Math Tabriz Iran Univ Lisbon Ctr Matemat Aplicacooes Fundamentais & Invest Ope Fac Ciencias P-1749016 Lisbon Portugal

This paper addresses the optimal scheduling of straight pipelines featuring multiple intermediate nodes acting as dual-purpose stations, with a continuous-time mixed-integer linear programming formulation partly derived from Generalized Disjunctive programming. The new model allows for an intermediate station to act as an output and input terminal at the same time so as to reduce the number of segment switches between active and idle, and consequently decrease operating costs. Contrary to previous approaches, decisions related to batch sizing, batch sequencing and timing are determined in a single step. Several examples of growing complexity are solved to illustrate the effectiveness and computational advantage of the proposed model in both solution quality and CPU time. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Mathematical modeling mixed-integer linear programming Generalized disjunctive programming Multiproduct pipelines

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Arterial traffic signal optimization: A person-based approach

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TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES 2016年 66卷 27-47页

作者： Christofa, Eleni Ampountolas, Konstantinos Skabardonis, Alexander Univ Massachusetts Dept Civil & Environm Engn Amherst MA 01003 USA Univ Glasgow Sch Engn Glasgow G12 8LT Lanark Scotland Univ Calif Berkeley Inst Transportat Studies Berkeley CA 94720 USA

This paper presents a real-time signal control system that optimizes signal settings based on minimization of person delay on arterials. The system's underlying mixed integer linear program minimizes person delay by explicitly accounting for the passenger occupancy of autos and transit vehicles. This way it can provide signal priority to transit vehicles in an efficient way even when they travel in conflicting directions. Furthermore, it recognizes the importance of schedule adherence for reliable transit operations and accounts for it by assigning an additional weighting factor on transit delays. This introduces another criterion for resolving the issue of assigning priority to conflicting transit routes. At the same time, the system maintains auto vehicle progression by introducing the appropriate delays associated with interruptions of platoons. In addition to the fact that it utilizes readily available technologies to obtain the inputs for the optimization, the system's feasibility in real-world settings is enhanced by its low computation time. The proposed signal control system is tested on a four-intersection segment of San Pablo Avenue arterial located in Berkeley, California. The findings show the system's capability to outperform pretimed (i.e., fixed-time) optimal signal settings by reducing total person delay. They have also demonstrated its success in reducing bus person delay by efficiently providing priority to transit vehicles even when they travel in conflicting directions. (C) 2015 Elsevier Ltd. All rights reserved.

关键词： Person-based traffic signal control Transit signal priority Person delay mixed-integer linear programming Conflicting transit routes Pairwise signal optimization

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Decomposition algorithms for optimizing multi-server appointment scheduling with chance constraints

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MATHEMATICAL programming 2016年第1期157卷 245-276页

作者： Deng, Yan Shen, Siqian Univ Michigan Dept Ind & Operat Engn Ann Arbor MI 48109 USA

This paper investigates a problem of scheduling appointments with random service durations on multiple servers with operating time limits. We minimize the cost of operating servers and serving appointments, subject to a joint chance constraint limiting the risk of server running overtime. With finite samples of random service time, we consider a mixed-integer linear programming extended formulation and propose a two-stage decomposition framework with cutting planes. The first stage considers a relaxed master problem as a variant of the chance-constrained binary packing problem discussed in Song et al. (INFORMS J Comput 26(4):735-747, 2014), which packs appointments into servers under chance-constrained server overtime. Given appointment-to-server assignments, the second stage seeks feasible schedules on individual servers. We propose strengthening, bounding, and branch-and-cut methods for computing problems in both stages. Via testing instances with diverse sizes, we compare different decomposition schemes. In particular, we demonstrate the efficacy of our branch-and-cut algorithm that incorporates server-based decomposition for optimizing the problem.

关键词： Chance-constrained programming Service scheduling mixed-integer linear programming Decomposition Branch-and-cut

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Under-Frequency Load Shedding Technique Considering Event-Based for an Islanded Distribution Network

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JOURNAL OF ELECTRICAL SYSTEMS 2016年第3期12卷 574-582页

作者： Mohamad, Hasmaini Isa, Amalina Izzati Md Mokhlis, Hazlie Dahlan, Nofri Yenita Musirin, Ismail Univ Teknol MARA Fac Elect Engn Shah Alam 40450 Selangor Malaysia Univ Malaya Dept Elect Engn Fac Engn Kuala Lumpur 50603 Malaysia

One of the biggest challenge for an islanding operation is to sustain the frequency stability. A large power imbalance following islanding would cause under-frequency, hence an appropriate control is required to shed certain amount of load. The main objective of this research is to develop an adaptive under-frequency load shedding (UFLS) technique for an islanding system. The technique is designed considering an event-based which includes the moment system is islanded and a tripping of any DG unit during islanding operation. A disturbance magnitude is calculated to determine the amount of load to be shed. The technique is modeled by using PSCAD simulation tool. A simulation studies on a distribution network with mini hydro generation is carried out to evaluate the UFLS model. It is performed under different load condition: peak and base load. Results show that the load shedding technique have successfully shed certain amount of load and stabilized the system frequency.

关键词： Electricity spot market bilateral contracts thermal unit commitment mixed-integer linear programming

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linear approximated formulation of AC optimal power flow using binary discretisation

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IET GENERATION TRANSMISSION & DISTRIBUTION 2016年第5期10卷 1117-1123页

作者： Akbari, Tohid Bina, Mohammad Tavakoli KN Toosi Univ Technol Fac Elect Engn Tehran Iran

This study presents a novel linear approximated methodology for full alternating current-optimal power flow (AC-OPF). The AC-OPF can provide more precise and real picture of full active and reactive power flow modelling, along with the voltage profile of buses compared to the commonly used direct current-optimal power flow. While the AC-OPF is a non-linear programming problem, this can be transformed into a mixed-integer linear programming environment by the proposed model without loss of accuracy. The global optimality of the solution for the approximated model can be guaranteed by existing algorithms and software. The numerical results and simulations which represent the effectiveness and applicability of the proposed model are given and completely discussed in this study.

关键词： load flow nonlinear programming integer programming linear programming linear approximated formulation AC optimal power flow binary discretisation linear approximated methodology full alternating current-optimal power flow AC-OPF reactive power flow modelling voltage profile direct current-optimal power flow nonlinear programming problem mixed-integer linear programming

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Operation management of residential energy-supplying networks based on optimization approaches

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APPLIED ENERGY 2016年 183卷 340-357页

作者： Wakui, Tetsuya Kawayoshi, Hiroki Yokoyama, Ryohei Aki, Hirohisa Osaka Prefecture Univ Dept Mech Engn Naka Ku 1-1 Gakuen Cho Sakai Osaka 5998531 Japan Natl Inst Adv Ind Sci & Technol Res Inst Sci Safety & Sustainabil 1-1-1 Umezono Tsukuba Ibaraki 3058568 Japan

An operation management system for residential energy-supplying networks using multiple cogeneration units was developed by hierarchically integrating energy demand prediction, operational planning, and operational control, using optimization approaches. The energy demand for multiple dwellings was predicted by support vector regression with information on occupant behavior as well as forecasted weather and energy demand history. mixed-integer linear programming was employed for the operational planning of the cogeneration units to the predicted energy demand. The energy demand prediction and operational planning were updated using a variable frequency receding horizon approach. This was done to limit the unnecessary shutdown and start-up of the cogeneration units and to reduce the influences of prediction errors for energy demand. Regarding the operational control, the actual on-off schedule of the cogeneration units conformed to the operational planning result. Additionally, the power and heat outputs of the cogeneration units and the heat supply from the storage tanks were modulated in response to the actual energy demand, based on predefined rules. The developed operation management system was applied to annual operation simulation of a residential energy-supplying network consisting of four cogeneration units using fuel cells in a housing complex. For comparative analysis, history-based approaches for energy demand prediction and separate operation of each cogeneration unit were also considered. The results revealed the effectiveness of the developed operation management system as well as the high energy-saving performance of the residential energy-supplying network. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Energy management Microgrid Cogeneration Model predictive control Support vector regression mixed-integer linear programming

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A new multi-objective mathematical model for the high-level synthesis of integrated circuits

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APPLIED MATHEMATICAL MODELLING 2016年第3期40卷 2274-2290页

作者： Aras, Necati Yurdakul, Arda Bogazici Univ Dept Ind Engn Istanbul Turkey Bogazici Univ Dept Comp Engn Istanbul Turkey

An integrated circuit contains millions of components, all of which have to fit in the reserved silicon area and fulfill a defined functionality within a specified amount of execution time. Therefore, the design of an effective integrated circuit is a nontrivial task. Actually, it can be considered as a multi-objective optimization problem with two conflicting objectives: minimizing the total execution time called latency and the total silicon area of the integrated circuit. The overall problem is composed of tightly-coupled subproblems, i.e., determining the allocation of operators that execute the operations, the assignment of operations to operators, and scheduling of the operations. We formulate a multi-objective mixed-integer linear programming model (MOMILP) to solve this complex problem. It is novel since it incorporates decisions about the so-called multiplexers, which are essential components of an integrated circuit. The proposed MOMILP model is solved exactly using an augmented epsilon-constrained method. This enables us to find all the Pareto optimal solutions and hence the Pareto frontier for a given problem instance within a reasonable amount of computation time. The minimum latency and minimum area solutions of our model are 13.20 and 7.24% better on the average than the model that ignores multiplexers. (C) 2015 Elsevier Inc. All rights reserved.

关键词： Integrated circuits Multiobjective optimization mixed-integer linear programming Pareto frontier

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Discrete optimization methods to fit piecewise affine models to data points

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COMPUTERS & OPERATIONS RESEARCH 2016年第Nov.期75卷 214-230页

作者： Amaldi, E. Coniglio, S. Taccari, L. Politecn Milan Dipartimento Elettron Informaz & Bioingn Piazza Leonardo Vinci 32 I-20133 Milan Italy Univ Southampton Dept Math Sci Univ Rd Southampton SO17 1BJ Hants England

Fitting piecewise affine models to data points is a pervasive task in many scientific disciplines. In this work, we address the k-Piecewise Affine Model Fitting with Piecewise linear Separability problem (k-PAMF-PLS) where, given a set of m points {a(1),...,a(m)} subset of R-n and the corresponding observations {b(1),...,b(m)} subset of R, we have to partition the domain R-n into k piecewise linearly (or affinely) separable subdomains and to determine an affine submodel (i.e., an affine function) for each of them so as to minimize the total linear fitting error w.r.t. the observations b(i). To solve k-PAMF-PLS to optimality, we propose a mixed-integer linear programming (MILP) formulation where symmetries are broken by separating shifted column inequalities. For medium-to-large scale instances, we develop a four-step heuristic involving, at each iteration, a point reassignment step based on the identification of critical points and a domain partition step based on multicategory linear classification. Differently from traditional approaches proposed in the literature for similar fitting problems, in both our exact and heuristic methods the domain partitioning and submodel fitting aspects are taken into account simultaneously. Computational experiments on real-world and structured randomly generated instances show that, with our MILP formulation with symmetry breaking constraints, we can solve to proven optimality many small-size instances. Our four-step heuristic turns out to provide close-to-optimal solutions for the small size instances, while allowing to tackle instances of much larger size. The experiments also show that the combined impact of the main features of our heuristic is quite substantial when compared to standard variants not including them. We conclude the paper with an application to the identification of dynamical, piecewise affine systems, for which we obtain promising results of comparable quality with those achieved with state-of-the-art methods

关键词： Data mining Piecewise affine model fitting mixed-integer linear programming Heuristics

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A shortcut model for energy efficient water network synthesis

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APPLIED THERMAL ENGINEERING 2016年第0期96卷 88-91页

作者： Liang, Yingzong Hui, Chi-Wai Hong Kong Univ Sci & Technol Dept Chem & Biomol Engn Kowloon Hong Kong Peoples R China

This paper presents a shortcut model for energy efficient water network synthesis with single contaminant. The proposed model is based on the idea of reducing repeated heating and cooling proposed by Feng et al. [9]. To avoid sub-optimum that can be generated from Feng's model, the proposed model only minimizes the number of temperature 'valleys' instead of the total number of 'peaks and valleys' of the water network. With the new formulation, the proposed model not only guarantees global optimum but also becomes much easier to be solved. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Water allocation network Heat integration mixed-integer linear programming

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A novel two-model based approach for optimal scheduling in CSP plants

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SOLAR ENERGY 2016年 126卷 73-92页

作者： Jesus Vasallo, Manuel Manuel Bravo, Jose Univ Huelva Dept Elect Engn Comp Syst & Automat Carretera Palos de La Frontera S-N Palos De La Frontera 21819 Huelva Spain

Thermal energy storage (TES) systems allow concentrated solar power (CSP) producers to participate in a day-ahead market. Then, the optimal power scheduling problem can be posed, whose objective is the maximisation of profits derived from electricity sales. Most papers in literature use a mixed-integer linear programming (MILP) approach to solve this type of problems. This paper proposes a novel approach based on the use of two models: a detailed model and a MILP model. This approach combines MILP capabilities and the accuracy of a detailed model. The proposed approach is applied to a 50 MW parabolic-trough-collector based CSP plant with molten-salt-based TES. A detailed model available in literature and validated against operating plant data is used, but some improvements are included for its use in optimal scheduling problems. Moreover, the MILP model was developed to adjust as much as possible to the features of the detailed model. The improvements regarding other scheduling strategies for a specific example are shown. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： Concentrating solar power plant Thermal energy storage Electricity market Optimized operation strategy Parabolic trough collector mixed-integer linear programming

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