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A mixed-integer programming-based Q-learning approach for electric bus scheduling with multiple termini and service routes

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TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES 2024年 162卷

作者： Yan, Yimo Wen, Haomin Deng, Yang Chow, Andy H. F. Wu, Qihao Kuo, Yong -Hong Univ Hong Kong Dept Ind & Mfg Syst Engn Hong Kong Peoples R China Beijing Jiaotong Univ Dept Comp Sci Beijing Peoples R China Natl Univ Singapore Dept Comp Sci Singapore Singapore Xian Univ Sci & Technol Sch Management Xian Peoples R China City Univ Hong Kong Dept Syst Engn Hong Kong Peoples R China Hong Kong Univ Sci & Technol Inst Environm HKU Musketeers Fdn Hong Kong Peoples R China

Electric buses (EBs) are considered a more environmentally friendly mode of public transit. In addition to other practical challenges, including high infrastructure costs and short driving ranges, the operations of EBs are more demanding due to the necessary battery charging activities. Consequently, more sophisticated optimisation models and algorithms are required for effective operations. This paper presents an EB scheduling problem with multiple termini and service routes. Various realistic but complicated factors, such as shared facilities at multiple termini, the flexibility of plugging and unplugging chargers before an EB is fully charged, stochastic travel times, and EB breakdowns, are considered. We propose an integrated learning and mixed -integer linear programming (MILP) framework to overcome the computational difficulties when solving the problem. This framework leverages the strengths of reinforcement learning and MILP for fast computations due to its capability of learning from outcomes of state-action pairs and computational effectiveness guaranteed by the constraints governing the solution feasibility. Q -Learning and Twin Delayed Deep Deterministic Policy Gradient are adopted as our training methods. We conduct numerical experiments on artificial instances and realistic instances of a bus network in Hong Kong to assess the performance of our proposed approach. The results show that our proposed framework outperforms the benchmark optimisation approach, in terms of penalty on missed service trips, average headway, and variance of headway. The benefits of our proposed framework are more significant under a highly stochastic environment.

关键词： Electric buses Public transport mixed-integer linear programming Q-learning

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Modeling and solving mixed-model assembly line balancing problem with setups. Part I: A mixed integer linear programming model

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JOURNAL OF MANUFACTURING SYSTEMS 2014年第1期33卷 177-187页

作者： Akpinar, Sener Baykasoglu, Adil Dokuz Eylul Univ Fac Engn Dept Ind Engn Izmir Turkey

This paper is the first one of the two papers entitled "modeling and solving mixed-model assembly line balancing problem with setups", which has the aim of developing the mathematical programming formulation of the problem and solving it with a hybrid meta-heuristic approach. In this current part, a mixed-integer linear mathematical programming (MILP) model for mixed-model assembly line balancing problem with setups is developed. The proposed MILP model considers some particular features of the real world problems such as parallel workstations, zoning constraints, and sequence dependent setup times between tasks, which is an actual framework in assembly line balancing problems. The main endeavor of Part-I is to formulate the sequence dependent setup times between tasks in type-I mixed-model assembly line balancing problem. The proposed model considers the setups between the tasks of the same model and the setups because of the model switches in any workstation. The capability of our MILP is tested through a set of computational experiments. Part-II tackles the problem with a multiple colony hybrid bees algorithm. A set of computational experiments is also carried out for the proposed approach in Part-II.(C) 2013 The Society of Manufacturing Engineers. Published by Elsevier Ltd. All rights reserved.

关键词： mixed-model assembly line balancing mixed-integer linear programming Sequence dependent setup times Intra-station sequencing Zoning constraints Parallel workstations

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Two new mixed-integer programming models for the integrated train formation and shipment path optimization problem

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NETWORKS 2023年第3期81卷 359-377页

作者： Arsalani, Pouria Reisi-Nafchi, Mohammad Dardashti, Vahid Moslehi, Ghasem Isfahan Univ Technol Dept Ind & Syst Engn Esfahan Iran CIRRELT Montreal PQ Canada Isfahan Univ Technol Dept Ind & Syst Engn Esfahan *** Iran

Railcars are known as the heart of the freight rail transportation industry. Hence, any improvements in their operations can lead to sharp reductions in various operating costs. One of the most critical operations on railcars is blocking and routing their transportation. Railway companies face continuous challenged about what blocks should be formed to carry shipments across different origin-destination pairs (O-D pairs) and reclassify them in intermediate yards to minimize transportation reclassification costs. In addition, it is necessary to determine train service between O-D pairs and the number of trains. Along with the shipment routing plans, this problem is called train formation and shipment path optimization (TFSP). In TFSP, some substructure and rail network operational constraints should be considered, including link capacity, classification capacity, the number of sorting tracks, and path length. This paper presents two arc-based mixed-integer linear programming (MILP) models to formulate the TFSP problem. To the best of the authors' knowledge, no MILP arc-based model has been published for the problem that does not need any preprocess before solving. Computational results of solving models on the datasets showed that the first model could obtain a feasible solution with a maximum 0.05% gap up to 48 yards instance. The second model also could find a solution with a small gap compared to the optimal solution in a reasonable time for instances up to 128 yards. Also, the proposed models were compared to the best methods in the literature, and their superiority was shown.

关键词： mixed-integer linear programming railcar blocking railway transportation shipment path routing single-block train train formation

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Stronger mixed-integer programming-formulations for order- and rack-sequencing in robotic mobile fulfillment systems

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EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2023年第3期305卷 1063-1078页

作者： Justkowiak, Jan-Erik Pesch, Erwin Univ Siegen Management Informat Sci Kohlbettstr 15 D-57072 Siegen Germany HHL Leipzig Ctr Adv Studies Management Jahnallee 59 D-04109 Leipzig Germany

This paper addresses the order-and rack-sequencing problem at a single picking station in the context of robotic mobile fulfillment systems, a warehouse technology typically applied in large distribution centers. Following the parts-to-picker concept, items are stored on movable racks that are lifted and transported by automated guided vehicles from the storage area to picking stations for order-processing. The order-picking process involves two linked decisions: How to sequence the processing of orders and how to se-quence the rack visits to supply the picking station with the requested items. We present a novel mixed-integer linear programming formulation achieving stronger linear programming bounds than a previous formulation. Including preprocessing techniques it quickly solves instances of medium-size to proven op-timality for the first time in literature. For large real-world instances, we provide a three-stage heuristic solution procedure suitable in a dynamic environment, while providing competitive solutions within a short run time. Computational experiments on a broad set of benchmark instances and a comparative study with approaches from literature verify our results.(c) 2022 Elsevier B.V. All rights reserved.

关键词： Scheduling Robotic mobile fulfillment systems mixed-integer linear programming Warehouse logistics Order-sequencing

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Hydro Unit Commitment via mixed integer linear programming: A Case Study of the Three Gorges Project, China

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IEEE TRANSACTIONS ON POWER SYSTEMS 2014年第3期29卷 1232-1241页

作者： Li, Xiang Li, Tiejian Wei, Jiahua Wang, Guangqian Yeh, William W. -G. Tsinghua Univ State Key Lab Hydrosci & Engn Beijing 100084 Peoples R China Univ Calif Los Angeles Dept Civil & Environm Engn Los Angeles CA 90095 USA

This paper develops a methodology for optimizing the hydro unit commitment (HUC) for the Three Gorges Project (TGP) in China. The TGP is the world's largest and most complex hydropower system in operation. The objective is to minimize the total operational cost. The decision variables are the startup or shutdown of each of the available units in the system and the power releases from the online units. The mathematical formulation must take into account the head variation over the operation periods as the net head changes from hour to hour and affects power generation. Additionally, the formulation must consider the operation of 32 heterogeneous generating units and the nonlinear power generation function of each unit. A three-dimensional interpolation technique is used to accurately represent the nonlinear power generation function of each individual unit, taking into account the time-varying head as well as the non-smooth limitations for power output and power release. With the aid of integer variables that represent the on/off and operation partition statuses of a unit, the developed HUC model for the TGP conforms to a standard mixed integer linear programming (MILP) formulation. We demonstrate the performance and utility of the model by analyzing the results from several scenarios for the TGP.

关键词： Hydro unit commitment hydropower mixed-integer linear programming Three Gorges Project (China)

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Modelling overflow using mixed integer programming in short-term hydropower scheduling

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ENERGY SYSTEMS-OPTIMIZATION MODELING SIMULATION AND ECONOMIC ASPECTS 2023年 1-13页

作者： Litlabo, Tormod Aaslid, Per Riise, Tarjei Lid Haugland, Dag Sweco Norge AS Fantoftvegen 14P N-5072 Bergen Norway SINTEF Energy Res Dept Energy Syst Sem Saelands Vei 11 N-7034 Trondheim Norway Eviny Fornybar AS Solheimsgaten 5 N-5058 Bergen Norway Univ Bergen Dept Informat Thormohlensgate 55 N-5008 Bergen Norway

Short-term hydropower scheduling seeks to find a production schedule that maximizes profit, but must also consider the hydrological balance and risk of overflow. Overflow is by nature a non-linear and non-convex phenomenon. Common approximations and relaxations may cause non-physical results such as overflow from reservoirs that are not full. This paper presents a mixed-integer linear programming formulation that can be used to prevent non-physical overflow behaviour, but that comes at a cost of significant higher solving time. To achieve an acceptable solving time, we propose a heuristic to provide tight upper bounds on the overflow variables in each time step. When applied on the model of the Fossdal watercourse in Norway, the proposed method reduces the solving time with more than 90% compared to using a conservative fixed coefficient for all time steps.

关键词： Short-term hydropower scheduling Overflow mixed-integer linear programming Successive linear programming

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A sequential mixed-integer programming method for concurrent optimization of core topology and face sheet thickness of a sandwich beam

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JOURNAL OF SANDWICH STRUCTURES & MATERIALS 2023年第6期25卷 666-686页

作者： Larsson, Johan Goeransson, Peter Wennhage, Per KTH Royal Inst Technol Stockholm Sweden Ctr ECO2 Vehicle Design Stockholm Sweden KTH Royal Inst Technol Dept Engn Mech Teknikringen 8 S-11428 Stockholm Sweden

A method is proposed that allows for the concurrent optimization of core topology and face sheet thickness of a sandwich beam under compliance constraints. The problem is solved using a novel mixed-linear extension of the Topology Optimization of Binary Structure (TOBS) topology optimization method aiming to minimize the total mass of the beam. The method has been demonstrated on a clamped beam example and the results have been compared to results from topology optimization of the core with a range of a priori fixed face sheet thicknesses. It is shown that the new method, starting from a fully populated core, finds a minimum mass that is lower than but in the neighbourhood of the best results from the topology optimization with fixed face sheet thicknesses. By varying the compliance constraint it is shown that the core topology approaches an ideal corrugated geometry as the compliance constraint is relaxed. The trends observed in the results are compared to analytical models for an idealized core.

关键词： Topology optimization sandwich structures mixed-integer linear programming concurrent optimization mass minimization

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Resilience-Oriented Train Rescheduling Optimization in Railway Networks: A mixed integer programming Approach

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IEEE TRANSACTIONS ON INTELLIGENT TRANSPORTATION SYSTEMS 2023年第5期24卷 4948-4961页

作者： Yin, Jiateng Ren, Xianliang Su, Shuai Yan, Fei Tao, Tang Beijing Jiaotong Univ State Key Lab Rail Traff Control & Safety Beijing Peoples R China CRSC Res & Design Inst Grp Co Ltd Beijing Peoples R China

Due to the inventible disruptions caused by e.g., flood, hurricane and blizzard, metro managers in recent years have gradually shifted their attention from prevention of disruptions to ability to withstand and quick recovery from these disruptions, hence the need for enhancing the resilience of an urban rail system. In this paper, we propose a resilience-oriented train rescheduling framework, which helps the rail transit system recover to the normal state as soon as possible in case of disruptions, with the help of pre-allocated rolling stocks at the depots, side tracks and timetable rescheduling of grains. Specifically, we first construct an event-activity network for an urban rail line with multiple depots and side tracks, in which the arrival and departure of trains are modeled as a set of events. Several groups of decision variables and linear constraints are denoted to model the rescheduling of trains. Considering the use of short-turning train rescheduling strategy and pre-allocated rolling stocks, we then formulate the problem into a mixed-integer linear programming (MILP) model, where the objective is to maximize the resilience of the urban rail line against disruptions. Through the analysis of model properties, we develop a branch-and-cut algorithm by deriving a series of linear inequalities, which we prove are valid inequalities, to strength the tightness of the MILP model. Finally, numerical experiments based on real-world data of Beijing metro are conducted to verify the effectiveness of our approach.

关键词： Rails Resilience Rail transportation Numerical models Computational modeling Optimization Real-time systems disruption management mixed-integer linear programming

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Optimal Operations of Nuclear-based Integrated Energy Systems with mixed-integer programming

Optimal Operations of Nuclear-based Integrated Energy System...

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IEEE Texas Power and Energy Conference (TPEC)

作者： Huang, Jianqiao Li, Binghui Poudel, Bikash Zhang, Jie Idaho Natl Lab Idaho Falls ID 83415 USA Univ Texas Dallas Richardson TX USA

ISBN: (纸本)9798350331202

A nuclear-based integrated energy system (IES), consisting of multiple carbon-free energy generation and conversion technologies to meet heterogeneous end-use demands, offers a promising approach to decarbonize the U.S. economy. Operating such an IES is challenging due to its complexity and the diverse end-use demands, such as heating and electricity. This paper aims to address the optimal operation of an IES composed of a small modular reactor, a steam manifold, a balance of plant, a high-temperature steam electrolysis system, a district heating (DH) network, and electrical grids. We formulate the system's operation as a mixed-integer linear programming problem to maximize net revenues from sales of electricity and hydrogen. To evaluate the efficacy of the proposed model, we conduct a 24-hour simulation considering day-ahead electricity prices from the California Independent System Operator (CAISO) and a varying DH demand profile with hourly resolution. The simulation results show that our model effectively optimizes the operation by selling electricity during on-peak periods and purchasing electricity for hydrogen production during off-peak periods, while satisfying operating constraints within the IES.

关键词： Integrated energy system cascade heat utilization mixed-integer linear programming small modular reactor

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Optimal Single-Item Replenishment Scheme and Pricing Strategy for Vegetable Category Based on LSTM Time-Series Prediction mixed integer programming Model

Optimal Single-Item Replenishment Scheme and Pricing Strateg...

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2024 International Conference on Interactive Intelligent Systems and Techniques, IIST 2024

作者： Huang, Zhikun Huang, Zhijie Wu, Wenjian Huang, Yufei Jiangxi University of Finance and Economics School of Information Management Jiangxi China

ISBN: (纸本)9798350374421

The replenishment and pricing of superstore vegetables is an important part of daily life, and the merchants' prediction and optimisation scheme for the future has gradually become an important issue in production and life. This paper focuses on the problem of total replenishment and pricing strategy of superstores, predicts and analyses the results based on LSTM time-series prediction, and finally gives the optimal total replenishment and pricing strategy of superstores in different scenarios. Firstly, the data are preprocessed to filter out the types of products available for sale from 24-30 June 2023 Meanwhile, based on the LSTM time-series prediction model, the basic relationship between short-term sales quantity and pricing is predicted. Then, under the premise of trying to meet the market demand for each category of vegetable goods, a mixed integer programming model aimed at maximising the benefits of the business dynasty is established, the 0-1 variable is introduced to constrain the selection of single products, and multiple constraints are established on the number of single products, the order quantity of single products, and the demand for each type of goods, which is solved to produce a profit of 1098.360 yuan on 1 July. Finally, based on a simple model perturbation, it is judged that the scheme is more reasonable and the result is superior, and finally gives the optimal single-item replenishment scheme and pricing strategy. © 2024 IEEE.

关键词： mixed-integer linear programming

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