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mixed-integer model predictive control for large-area MR-HIFU hyperthermia in cancer therapy ⁎

IFAC-PapersOnLine 2020年第2期53卷 6637-6643页

作者： D.A. Deenen E. Maljaars L. Sebeke B. de Jager E. Heijman H. Grüll W.P.M.H. Heemels Eindhoven University of Technology Mechanical Engineering Control Systems Technology Eindhoven The Netherlands University Hospital of Cologne Cologne Germany Philips Research Germany Aachen Germany

In hyperthermia treatments, cancer tissue is heated to enhance the desired effects of radio- and chemotherapies. A powerful technology for noninvasive feedback-controlled hyperthermia is magnetic-resonance-guided high-intensity focused ultrasound (MR-HIFU), which enables fast and millimeter-accurate heating inside the body. Electronic beam steering allows for volumetric heating, but due to its limited steering range can only be used to treat small tumors. For the treatment of larger tumors, the transducer itself must be mechanically relocated as well. Due to system limitations, however, the admissible transducer positions must be restricted to a finite set that is chosen a priori. Moreover, non-negligible time is needed for transducer relocation, during which no heating is possible. In this paper, we present a mixed-integer model predictive controller that simultaneously optimizes over the power deposition by electronic beam steering - a continuous subproblem - as well as the mechanical transducer motions - a discrete subproblem. By incorporating model knowledge of the tissue’s thermal response and of the transducer carrier motion system into the predictive algorithm, the controller optimizes treatment temperature while respecting temperature and actuation constraints. The performance of the proposed feedback control setup is demonstrated by means of simulation.

关键词： Model predictive control mixed-integer programming switched systems hyperthermia cancer treatment large-area high-intensity focused ultrasound

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Energy Optimal Coordination of Fully Autonomous Vehicles in Urban Intersections

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IFAC-PapersOnLine 2020年第2期53卷 15090-15095页

作者： C. Pelosi G.P. Padilla M.C.F. Donkers Dept Electrical Eng Eindhoven University of Technology Netherlands

This paper provides a solution to conflict resolutions between Autonomous Vehicles (AV) crossing an urban intersection. The conflict resolution problem is formulated as an optimal control problem, where the objective is to minimize the energy consumption of all the vehicles, while avoiding collisions. Since the problem has a combinatorial nature, it is tackled though a sequential mixed-integer quadratically constrained programming approach. Simulation results show that since the AVs do not need to follow specific driving rules, the intersection crossing order is chosen to optimize the overall energy consumption. The research outcome underlines the benefits of moving towards fully autonomous systems which will allow for higher traffic throughput. Furthermore, the proposed formulation is the starting point for future explorations towards real-time implementation.

关键词： Autonomous Vehicles Eco-Driving Optimal Control mixed-integer programming

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Optimal Location of Submain Tracks on an Urban Railway Line

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JOURNAL OF TRANSPORTATION ENGINEERING PART A-SYSTEMS 2020年第9期146卷

作者： Oh, Suk-Mun Kim, Kyung Min Korea Railroad Res Inst Transport Syst Res Team 176 Cheoldobangmulgwan Ro Uiwang Si 16105 Gyeonggi Do South Korea Myongji Univ Dept Ind Management & Engn 116 Myongji Ro Yongin 17058 Gyeonggi Do South Korea

Determining the location of submain tracks (SMTs) or sidings to accommodate flexible operation is a critical issue in supporting construction investments and meeting passenger preferences. This project considered the problem of calculating the optimal location of SMTs. The objective was to minimize the sum of the construction costs for the SMTs and the total delay cost for passengers. We introduced properties for two train types. Additionally, we developed a mixed-integer model for multiple train types. We propose a procedure for using our model to determine the locations of SMTs for various headways and traffic mixes, and conducted numerical experiments to verify its performance. The results confirmed that our procedure is practical for an urban railway because the average total delay does not increase by more than about 55% compared with the optimal solution for any operational scheme. (c) 2020 American Society of Civil Engineers.

关键词： Submain tracks (SMTs) Optimal location Urban railway mixed-integer programming

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Systematic generation of alternative production schedules

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AICHE JOURNAL 2020年第5期66卷

作者： Lee, Hojae Gupta, Dhruv Maravelias, Christos T. Univ Wisconsin Madison Dept Chem & Biol Engn 1415 Engn Dr Madison WI 53706 USA

We propose a systematic approach for generating alternative production schedules to address two challenges in implementing optimization-based scheduling techniques in industrial settings: (a) the limited scope of the scheduling models due to modeling simplifications, and (b) the consideration of shop-floor nervousness. We first introduce metrics to quantify specific characteristics of a schedule (e.g., number of batches and degree of nervousness). Next, we favor, at different degrees, such characteristics in each alternative schedule, by penalizing the metrics in the objective function. Through illustrative instances, we show that multiple alternative schedules, including schedules with desired properties can readily be generated.

关键词： mixed-integer programming nervousness online scheduling

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An MIP-based model for the deployment of fault indicators and sectionalizing switches in distribution networks

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ELECTRIC POWER SYSTEMS RESEARCH 2020年 179卷

作者： Wang, Longjun Lin, Jian Liu, Guowei Wang, Gang Zhong, Qing Zhao, Yuming South China Univ Technol Sch Elect Power Engn Guangzhou 510640 Guangdong Peoples R China Shenzhen Power Supply Co Ltd Shenzhen 518001 Guangdong Peoples R China

Fault indicators (FIs) and sectionalizing switches (SSs) are of great importance in distribution automation for reliability enhancement and efficiency improvement. However, their types and locations have great effects on the resulting service quality. This paper intends to develop a model for the optimal simultaneous allocation of FIs and SSs in a complex distribution network based on reliability and cost-benefit analyses. Three position matrices are obtained by preprocessing the topology of distribution networks to enable the establishment of the proposed model. Furthermore, a quantification method for the customer interruption duration under different contingencies is constructed to achieve a more precise and practical reliability evaluation. The resultant optimization problem is formulated as a mixed-integer linear programming that can obtain the global optimal solution in a finite number of iterations. An IEEE 33-bus network and a real urban distribution system are used to verify the effectiveness and efficiency of this model. The obtained outcomes show that simultaneously considering the placement of FIs and SSs can expedite the fault location and isolation processes, reduce the overall costs of the system and improve the service reliability.

关键词： Distribution system reliability Optimal allocation Position matrix mixed-integer programming Fault indicator Sectionalizing switch

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A mathematical model and tabu search algorithm for multi-manned assembly line balancing problems with assignment restrictions

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ENGINEERING OPTIMIZATION 2020年第5期52卷 856-874页

作者： Yilmaz, Hamid Yilmaz, Mustafa Bayburt Univ Engn Fac Ind Engn Dept Bayburt Turkey Ataturk Univ Erzurum Engn Fac Ind Engn Dept Erzurum Turkey

A multi-manned assembly line is a set of workstations where task operations can be performed on multiple sides of the line. Such assembly lines are important for large products, such as buses, cars and trucks. In this study, a mathematical model for multi-manned assembly lines with assignment restrictions is proposed. The purpose of the mathematical model is to minimize the total number of workers and open multi-manned workstations along the line for a given cycle time simultaneously under various assignment restrictions. The model provides a more realistic situation for multi-manned assembly line problems. The tabu search algorithm (TSA) is also used to solve the problem. The performances of both methods on well-known data-set problems are analysed. Based on the computational experiments, the performance of the proposed TSA is compared with the mathematical model solutions on various problem instances. The experimental results verify the effectiveness and efficiency of the proposed TSA.

关键词： Assembly line balancing multi-manned workstations mixed-integer programming tabu search algorithm assignment restrictions

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A planning approach for polymetallic mines using a sublevel stoping technique with pillars and ultimate stope limits

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ENGINEERING OPTIMIZATION 2020年第6期52卷 932-944页

作者： Sari, Yuksel Asli Kumral, Mustafa McGill Univ Dept Min & Mat Engn Montreal PQ Canada

A widely used unsupported underground mining technique is sublevel stoping, in which portions of ore-body within certain size constraints are extracted. In this article, a sequential approach is proposed to solve the sublevel determination problem, which is part of development and infrastructure planning, and the stope layout planning problem for polymetallic sublevel stope mining with pillars. First, a new algorithm is proposed to determine the sublevels, which focuses on minimizing the development costs while maintaining access to the profitable portions of the ore-body. Then, the stope layout is planned between the sublevels. A new mixed-integer linear programming formulation for determining the ultimate stope limits is introduced. A case study is conducted on a copper-molybdenum mine to demonstrate the proposed approaches. The results show that the output of the stope layout plan is within the optimal mining limits, which confirms the validity of the approach.

关键词： Sublevel stoping with pillars stope layout planning heuristics ultimate stope limits mixed-integer programming

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Co-optimization of thermal power plant flowchart, thermodynamic cycle parameters, and design parameters of components

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ENERGY 2020年 193卷 483-496页

作者： Kler, Aleksandr M. Potanina, Yulia M. Marinchenko, Andrey Y. Russian Acad Sci ESI SB RAS Siberian Branch Melentiev Energy Syst Inst 130 Lermontov Str Irkutsk Russia

The improvement in the efficiency of an energy plant depends on a rational development of its flowchart and choice of parameters along with the load schedule, equipment reliability, operating mode, etc. It is advisable to study such complex technical systems with the methods of mathematical modeling and optimization. The paper presents an approach to the development of optimal flowcharts and selection of parameters of energy plants. The approach is based on the combination of a method for optimization of the most complex flowchart and a method for solving discrete-continuous problems of nonlinear mathematical programming. A case study of the co-optimization of design parameters, operating parameters and equipment mix for the integrated gasification combined-cycle plant is demonstrated. The optimization calculations were carried out by the criterion of the minimum price of electricity for a given internal rate of return on investment and the maximum energy efficiency of the plant. Several optimal solutions meeting the different criteria are obtained. The proposed approach can be used for optimization of flowcharts and parameters of other complicated energy plants (high-efficiency combined-cycle plants, ultra-supercritical steam cycles, integrated power plants for electricity and synthetic liquid fuel co-production from coal, etc.). (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Mathematical modeling Thermal power plants Methods of optimization mixed-integer programming Reversible processes Branch-and-bound method

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Optimal design and operation of River Basin Storage

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OMEGA-INTERNATIONAL JOURNAL OF MANAGEMENT SCIENCE 2020年 95卷

作者： Burrow, Andy Newman, Alexandra Colorado Sch Mines Dept Mech Engn 1500 Illinois St Golden CO 80401 USA

The State of Colorado's Stream Simulation Model (StateMod) provides comparative analysis for historical and future water resource decisions and policies along the Lower South Platte River. In order to identify locations for increased water storage, our research uses simulated data produced by StateMod as input to a mixed integer-linear optimization model. This model minimizes the cost of meeting unmet demands by assigning network flow of, and designing additional storage for, excess water while adhering to constraints that force the physical and topographical structures of the river. Using historical, measured flow data from 1962 through 2012, we extend the capability of StateMod by considering solutions with the following characteristics: (1) a single-reservoir solution, (2) a solution in which we only expand existing reservoirs, and (3) a solution without the constraints in (1) or (2). We conclude that, for the time horizon considered, the optimal method to mitigate shortages is with the construction of a combination of smaller surface and sub-surface reservoirs, and a corresponding prescribed flow. The total increased storage volume is 25,378 acre-feet (AF). Our work can be used as a strategic analysis tool by planners and engineers to quickly identify the most effective reservoir locations and the order in which to build them, rather than examining every potential storage site and the time at which it should be built, if at all. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Water resource planning mixed-integer programming Underlying network structure Reservoir design River basin management

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Exact and heuristic approaches for the automated design of medical trainees rotation schedules

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OMEGA-INTERNATIONAL JOURNAL OF MANAGEMENT SCIENCE 2020年 97卷

作者： Castano, Fabian Velasco, Nubia Pontificia Univ Javeriana Dept Civil & Ind Engn Calle 18 118-250 Cali Colombia Univ Los Andes Sch Management Calle 21 1-20 Bogota Colombia

This article addresses the problem of designing rotation schedules for the training of medical students in a healthcare institution in Colombia. Rotations are carried out along the course of a six months time period during which students rotate through different services both during one or multiple fortnightly periods. The hospital receives trainees from different universities that present heterogeneous requirements, and must accomplish different rotations constraints even in those cases when they come from the same university. Two different approaches are proposed to tackle the problem. First, a mathematical programming model is considered. Secondly, a metaheuristic approach based on Variable Neighborhood Search is adapted to solve the problem in an efficient manner. In both cases the objective function is proposed to be either a linear or a quadratic function that seeks a stable allocation of personnel to the services all along the considered time horizon. The proposed techniques are implemented as a part of a basic spreadsheet that helps personnel in charge generate, validate and fix the proposed plans as needed. The effectiveness of the methodology is tested through ex-post analysis, comparing it against schedules generated by the personnel in charge at the hospital, and over simulated data. The results indicate that the applied metaheuristic is competitive against specialized optimization software and facilitates the work of optimization for the health professionals in charge, reducing the planning tasks from several days to minutes. (C) 2019 Elsevier Ltd. All rights reserved.

关键词： Medical rotations Healthcare services Scheduling Medical trainees mixed-integer programming Variable neighborhood search

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