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Energy and water optimization of an integrated bioethanol production process from molasses and sugarcane bagasse: A Colombian case

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FUEL 2020年 260卷

作者： Valderrama, Claudia Quintero, Viviana Kafarov, Viatcheslav Ind Univ Santander Physicochem Engn Dept Chem Engn 9 St 27 Santander Colombia Marina Univ Environm Engn Calle 18 34-104 Pasto Narino Colombia

In the present paper, an integrated scheme of first and second-generation bioethanol production is proposed to increase the yield and decreasing thermal energy and freshwater requirements. In this sense, an energy consumption reduction of the integrated process was evaluated through heat exchangers network integration, applying mathematical programming. Then, to reduce freshwater consumption, streams with water disposal for reuse in the process was evaluated, formulating the problem as a mixed-integer nonlinear programming problem (MINLP). Bioethanol production from the integrated scheme increased at least 40% compared it with sugar-bioethanol production scheme. The heat exchanger network with the minimum annual cost was identified. Around of 16% of freshwater consumption was minimized using a nonconvex nonlinear programming NLP. The integration of second-generation bioethanol to a sugar-bioethanol process could increase, the bioethanol production in Colombia, without an energy and water excessive consumption.

关键词： Bioethanol Exergy analysis Heat integration Water integration mixed-integer nonlinear programming

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Turnpike Properties in Discrete-Time mixed-integer Optimal Control

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IEEE CONTROL SYSTEMS LETTERS 2020年第3期4卷 704-709页

作者： Faulwasser, Timm Murray, Alexander TU Dortmund Univ Inst Energy Syst Energy Efficiency & Energy Econ D-44227 Dortmund Germany Karlsruhe Inst Technol Inst Automat & Appl Informat D-76131 Karlsruhe Germany

This note discusses properties of parametric discrete-time mixed-integer Optimal Control Problems (MIOCPs) as they often arise in model predictive control with discrete controls. We argue that, in want for a handle on similarity properties of parametric MIOCPs, the turnpike phenomenon known in optimal control is helpful. We provide sufficient turnpike conditions based on a dissipativity notion of MIOCPs, and we prove that the turnpike phenomenon allows specific and accurate guesses for the discrete controls. We also derive an easily checkable sufficient condition for dissipativity of linear-quadratic MIOCPs. Moreover, we show how the turnpike property can be used to derive efficient node-weighted branch-and-bound schemes tailored to parametric MIOCPs. We draw upon numerical examples to illustrate our findings.

关键词： Optimal control Steady-state Predictive control Optimization Sensitivity Economics Indexes Optimal control dissipativity mixed-integer optimization mixed-integer nonlinear programming

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Voltage and Reactive Power Optimization Using a Simplified Linear Equations at Distribution Networks with DG

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ENERGIES 2020年第13期13卷

作者： Go, Seok-Il Yun, Sang-Yun Ahn, Seon-Ju Choi, Joon-Ho Chonnam Natl Univ Dept Elect Engn Gwangju 61186 South Korea

In this paper, the VVO (Volt/Var optimization) is proposed using simplified linear equations. For fast computation, the characteristics of voltage control devices in a distribution system are expressed as a simplified linear equation. The voltage control devices are classified according to the characteristics of voltage control and represented as the simplified linear equation. The estimated voltage of distribution networks is represented by the sum of the simplified linear equations for the voltage control devices using the superposition principle. The voltage variation by the reactive power of distributed generations (DGs) can be expressed as the matrix of reactance. The voltage variation of tap changing devices can be linearized into the control area factor. The voltage variation by capacitor banks can also be expressed as the matrix of reactance. The voltage equations expressed as simplified linear equations are formulated by quadratic programming (QP). The variables of voltage control devices are defined, and the objective function is formulated as the QP form. The constraints are set using operating voltage range of distribution networks and the control ranges of each voltage control device. In order to derive the optimal solution, mixed-integer quadratic programming (MIQP), which is a type of mixed-integer nonlinear programming (MINLP), is used. The optimal results and proposed method results are compared by using MATLAB simulation and are confirmed to be close to the optimal solution.

关键词： Volt Var optimization distributed generation OLTC (On Load Tap Changer) mixed-integer nonlinear programming quadratic programming

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A generalized superstructure-based framework for process synthesis

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COMPUTERS & CHEMICAL ENGINEERING 2020年 133卷

作者： Ryu, Joonjae Kong, Lingxun de Lima, Arthur E. Pastore Maravelias, Christos T. Univ Wisconsin Dept Chem & Biol Engn 1415 Engn Dr Madison WI 53706 USA Univ Wisconsin DOE Great Lakes Bioenergy Res Ctr 1552 Univ Ave Madison WI 53726 USA

We propose a general framework for the formulation of superstructure-based optimization models for holistic process synthesis. First, we redefine the fundamental problems of reactor, separation, and heat exchanger network synthesis, by presenting generalized problem statements, to make them amenable to seamless integration with each other. Second, we describe the general forms of models that can be developed to address these generalized problems and identify some key characteristics. Notably, for each system, we identify internal variables used only within the system, cost variables used in the objective function, and, importantly, coupling variables for the coupling between systems. Third, we outline some literature models that can be used to address the generalized problems and present new models to couple the three systems. Finally, we show how the individual components (systems and coupling models) can be integrated to formulate a single simultaneous reactor, separation, and heat exchanger network synthesis. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Global optimization mixed-integer nonlinear programming Reactors Separations Heat integration Process design

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Global optimization of mixed-integer nonlinear (polynomial) programming problems: the Bernstein polynomial approach

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COMPUTING 2012年第2-4期94卷 325-343页

作者： Patil, Bhagyesh V. Nataraj, P. S. V. Bhartiya, Sharad Indian Inst Technol Syst & Control Engn Grp Bombay 400076 Maharashtra India Indian Inst Technol Dept Chem Engn Bombay 400076 Maharashtra India

In this paper, we propose an algorithm for constrained global optimization of mixed-integer nonlinear programming (MINLP) problems. The proposed algorithm uses the Bernstein polynomial form in a branch-and-bound framework. Ingredients such as continuous relaxation, branching for integer decision variables, and fathoming for each subproblem in the branch-and-bound tree are used. The performance of the proposed algorithm is tested and compared with several state-of-the-art MINLP solvers, on two sets of test problems. The results of the tests show the superiority of the proposed algorithm over the state-of-the-art solvers in terms of the chosen performance metrics.

关键词： Bernstein polynomials Branch-and-bound Global optimization mixed-integer nonlinear programming

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Multi-mode resource-constrained project scheduling with uncertain activity cost

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EXPERT SYSTEMS WITH APPLICATIONS 2021年 168卷

作者： Xie, Fang Li, Haitao Xu, Zhe Shandong Technol & Business Univ Coll Finance Yantai 264005 Peoples R China Shandong Technol & Business Univ Collaborat Innovat Ctr Financial Serv Transformat Yantai 264005 Peoples R China Univ Missouri Coll Business Adm St Louis MO 63121 USA Beihang Univ Coll Econ & Management Beijing 100191 Peoples R China

The multi-mode resource-constrained project scheduling problem under uncertain activity cost (MRCPSP-UAC) has a wide range of applications in production planning and project management. We first build a new mixed integer nonlinear programming (MINLP) model with the objective of minimizing the risk of project cost overrun, which provides a vehicle to obtain optimal solutions. To overcome the computational challenge of exact method for solving large instances, we devise a construction heuristic (CH) with a multi-pass greedy improvement procedure to obtain a feasible solution efficiently. To further improve solution quality, a hybrid CH and genetic algorithm (CH-GA) is developed with a custom fitness function to properly calibrate the quality of an individual. A comprehensive computational study is performed to examine the impact of various problem parameters on the optimal solutions, and the performance of our algorithms. Our hybrid CH-GA performs well for large instances with significantly less computational time than the exact method.

关键词： Resource-constrained project scheduling Multi-mode Uncertain activity cost mixed-integer nonlinear programming Genetic algorithms

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On the mathematical modeling for optimal selecting of calibers of conductors in DC radial distribution networks: An MINLP approach

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ELECTRIC POWER SYSTEMS RESEARCH 2021年 194卷

作者： Montoya, Oscar Danilo Gil-Gonzalez, Walter Grisales-Norena, Luis F. Univ Dist Francisco Jose de Caldas Fac Ingn Carrera 7 40B-53 Bogota 11021 DC Colombia Univ Tecnol Bolivar Lab Inteligente Energia Km 1 Via Turbaco Cartagena 131001 Colombia Inst Univ Pascual Bravo Fac Ingn Grp GIIEN Campus Robledo Medellin 050036 Colombia Inst Tecnol Metropolitan Dept Electromecan & Mecratron Medellin 050012 Colombia

This paper addresses the problem of optimal conductor selection in direct current (DC) distribution networks with radial topology. A nonlinear mixed-integer programming model (MINLP) is developed through a branch-to node incidence matrix. An important contribution is that the proposed MINLP model integrates a set of constraints related to the telescopic structure of the network, which allows reducing installation costs. The proposed model also includes a time-domain dependency that helps analyze the DC network under different load conditions, including renewable generation and battery energy storage systems, and different voltage regulation operative consigns. The objective function of the proposed model is made up of the total investment in conductors and the total cost of energy losses in one year of operation. These components of the objective function show multi-objective behavior. For this reason, different simulation scenarios are performed to identify their effects on the final grid configuration. An illustrative 10-nodes medium-voltage DC grid with 9 lines is used to carry out all the simulations through the General Algebraic Modeling System known as GAMS.

关键词： Direct current networks Medium-voltage distribution networks Radial structure Mathematical modeling mixed-integer nonlinear programming Telescopic configuration Optimal conductor selection

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Integrated supply chain scheduling of procurement, production, and distribution under spillover effects

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COMPUTERS & OPERATIONS RESEARCH 2021年 126卷

作者： Wang, Gang Univ Massachusetts Charlton Coll Business Dept Decis & Informat Sci 285 Old Westport Rd N Dartmouth MA 02747 USA

This paper considers an integrated scheduling problem in an e-commerce supply chain. The supply chain consists of heterogeneous suppliers, consumer-goods manufacturers that offer online channels, and a network of retailers. Suppliers provide raw materials or semi-finished products to manufacturers. Then, manufacturers produce and deliver end items to retailers. The retailers require that the manufac-turers maintain a given fill rate, and, otherwise, a penalty will apply. Missing the fill rate can not only result in penalties, but also retailers' switching, operational issues, and loss of image, and market value. Therefore, the total penalty costs are nonlinear with retailers' unsatisfied quantities and the fill rate, which exhibits spillover effects. The problem is to select a subset of suppliers, assign retailers' orders, and identify a production schedule with the manufacturers while minimizing the total costs that includes shipping and penalty. In this paper, we formulate a mixed-integer nonlinear program and develop a hybrid particle swarm optimization algorithm that can find a suitable solution within a reasonable time. The algorithm incorporates augmented Lagrangian relaxation and particle swarm optimization. We then perform computational testing on randomly generated cases and evaluate the performance of the proposed algorithm. Our numerical experiments show that the proposed algorithm is robust and efficient. Moreover, we provide a real case study, which demonstrates that the proposed model can lead to a substantial reduction of both the total and penalty costs. (C) 2020 Elsevier Ltd. All rights reserved.

关键词： Integrated scheduling Spillover effect mixed-integer nonlinear programming Augmented Lagrangian relaxation Particle swarm optimization

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A trust region framework for heat exchanger network synthesis with detailed individual heat exchanger designs

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COMPUTERS & CHEMICAL ENGINEERING 2021年 153卷

作者： Kazi, Saif R. Short, Michael Biegler, Lorenz T. Carnegie Mellon Univ Dept Chem Engn Pittsburgh PA 15213 USA Univ Surrey Dept Chem & Proc Engn Guildford Surrey England

We develop a trust region filter strategy for simultaneous optimal design of heat exchanger networks that includes detailed design of shell-and-tube heat exchangers. The strategy first solves a mixed-integer nonlinear programming (MINLP) formulation with shortcut models to generate candidate network topologies, which are then used in a non-isothermal mixing nonlinear programming (NLP) suboptimization with detailed optimal exchanger design models embedded using a modified trust region filter (TRF) algorithm. An integer cut based strategy is used to bound the solutions from MINLP and the NLP which aids in convergence to the solution of the overall simultaneous design problem. Under assumptions, the TRF based strategy can guarantee convergence to near optimal solutions of the overall design problem. The presented solution strategy is thus able to find optimal heat exchanger network designs based on the simultaneous optimization of the network topology and mass and energy balances, together with detailed shell-and-tube heat exchanger optimization, including the number of shell and tube passes, pressure drops, and tubes, tube lengths, etc. The proposed strategy is tested on three literature based case studies and their results are compared with previous studies to showcase its performance. (c) 2021 Elsevier Ltd. All rights reserved.

关键词： Heat exchanger network synthesis nonlinear programming mixed-integer nonlinear programming Trust region filter optimization Optimization Process system engineering

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Freeway network design with exclusive lanes for automated vehicles under endogenous mobility demand

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TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES 2021年 133卷

作者： Chakraborty, Shantanu Rey, David Levin, Michael W. Waller, S. Travis UNSW Sydney Sch Civil & Environm Engn Sydney NSW 2052 Australia Univ Minnesota Dept Civil Environm & Geoengn Minneapolis MN 55455 USA

Automated vehicles (AV) have the potential to provide cost-effective mobility options along with overall system-level benefits in terms of congestion and vehicular emissions. Additional resource allocation at the network level, such as AV-exclusive lanes, can further foster the usage of AVs rendering this mode of travel more attractive than legacy vehicles (LV). However, it is necessary to find the crucial locations in the network where providing these dedicated lanes would reap the maximum benefits. In this study, we propose an integrated mixed-integer programming framework for optimal AV-exclusive lane design on freeway networks which accounts for commuters' demand split among AVs and LVs via a logit model incorporating class-based utilities. We incorporate the link transmission model (LTM) as the underlying traffic flow model due to its computational efficiency for system optimum dynamic traffic assignment. The LTM is modified to integrate two vehicle classes namely, LVs and AVs with a lane-based approach. The presence of binary variables to represent lane design and the logit model for endogenous demand estimation results in a nonconvex mixed-integer nonlinear program formulation. We propose a Benders' decomposition approach to tackle this challenging optimization problem. Our approach iteratively explores possible lane designs in the Benders' master problem and, at each iteration, solves a sequence of system-optimum dynamic traffic assignment problems in an attempt to find fixed-points representative of logit-compatible demand splits. The proposed approach is implemented on three hypothetical freeway networks with single and multiple origins and destinations. Our numerical results reveal that the optimal lane design of freeway network is non-trivial while accounting for endogenous demand of each mode.

关键词： Benders decomposition mixed-integer nonlinear programming Freeway network design problem Endogenous demand Automated vehicles Exclusive lanes

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