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Exploiting the flexibility of modular buses in an urban transit system

TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES 2025年 175卷

作者： Filippi, Carlo Guastaroba, Gianfranco Peirano, Lorenzo Speranza, M. Grazia Univ Brescia Dept Econ & Management Brescia Italy

Urban transit systems usually operate according to fixed-route and fixed-schedule schemes by employing fixed-capacity vehicles, despite the mobility demand is unevenly spread out in both space and time. Modular buses are an emerging technology in which modules of relatively small capacity can be dynamically docked together to form greater capacity buses and can, therefore, make the transit system capable of adapting the capacity to the actual mobility demand. A module can be shifted from one line to another at pre-defined intersections and can be relocated when empty, if beneficial. We call these two operations sharing and rebalancing, respectively. Given a transit network comprising multiple bus lines and a mobility demand, we present an integer linear program to determine an optimal assignment of modules to lines, so that the mobility demand is met with a minimum total number of modules. Computational experiments show that, by exploiting the flexibility of modular buses, the total capacity deployed can be reduced by 49% with respect to a conventional transit system, whereas the average occupancy ratio increases from 41.22% to 72.85%.

关键词： Modular buses Flexible-capacity vehicles Transit systems integer linear programming

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Modelling and solving approaches for scheduling problems in reconfigurable manufacturing systems

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INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2024年第7期62卷 2683-2704页

作者： Delorme, Xavier Fleury, Gerard Lacomme, Philippe Lamy, Damien Univ Clermont Auvergne Mines St Etienne INP Clermont Auvergne Saint Etienne France Univ Clermont Auvergne Clermont Auvergne INP Mines St Etienne Clermont Ferrand France

Reconfigurable manufacturing systems (RMS) intend to bridge the gap between dedicated and flexible manufacturing systems. If the literature is mainly focused on the design step and tactical planning of such systems, few research projects have addressed scheduling at the operational level. While setup times may occur in flexible manufacturing systems, reconfiguration times considered in RMS may affect several resources at once, and hence require specific modelling and solving approaches to be considered. This paper first formalises the problem at hand through integer linear programming. An iterative search method is then provided to obtain solutions to larger-scale instances. Results obtained on generated instances show that managing even few possible configurations can yield significant improvements in solutions' quality. Meanwhile, the extended search space implied by the increase in available configurations hinders the convergence to a good solution in a reasonable computation time, which suggests further investigations.

关键词： Reconfigurable manufacturing systems integer linear programming metaheuristics scheduling setup times

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Shared automated mobility-on-demand system with different response, pricing and dispatching strategies

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TRANSPORTATION PLANNING AND TECHNOLOGY 2024年

作者： Yang, Yizhe Cui, Hongjun Zhu, Minqing Xie, Jinping Ma, Xinwei Hebei Univ Technol Sch Econ & Management Tianjin Peoples R China Hebei Univ Technol Sch Civil & Transportat Engn 5340 Xiping Rd Tianjin 300401 Peoples R China Hebei Univ Technol Sch Architecture & Art Design Tianjin Peoples R China

The shared automated mobility-on-demand system can offer convenient 'point-to-point' services for travelers. However, most previous studies have not combined pricing strategies with dispatching strategies to investigate their impact on system operation results. This paper proposes two demand response strategies for the shared automated mobility-on-demand system. From the perspective of time and space, eight ridesharing pricing strategies are proposed. The preliminary vehicle matching and routing are obtained through the integer linear programming considering system profit and service level, and the vehicle status is updated by four dispatching strategies that consider whether the matching scheme and route are updated over time. The results show that the factors taken into account in the ridesharing pricing strategy are restricted by the system to maximize profit, and the most flexible dispatching strategy is not the most profitable. These detailed analyses can provide a basis for formulating an effective operation mode of the automated mobility-on-demand system.

关键词： Automated mobility-on-demand system ridesharing integer linear programming response strategy ridesharing pricing strategy dispatching strategy

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Multichannel Pipelined Scheduling for Raw Data Convergecast in Sensor-Cloud

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MOBILE NETWORKS & APPLICATIONS 2024年第5期29卷 1646-1662页

作者： Sen, Biplab Kanti Khatua, Sunirmal Das, Rajib K. Univ Calcutta Dept Comp Sci & Engn Kolkata 100190 India

Convergecast is the process of gathering all sensor data at the base station. Convergecast in a Sensor-Cloud is achieved by creating multiple data-gathering trees over collaborating wireless sensor networks and collecting sensor data via those trees. Designing a schedule for convergecast can be one-shot (only for one round of data collection) or pipelined (data collected at regular intervals repeatedly). We give a pipelined algorithm for convergecast, assuming a raw data model (no aggregation). Firstly, we design a slot allocation algorithm considering only the adjacency constraints and traversing the trees in BFS (breadth first search) order. Our schedule requires at most M + H + 1 time slots for the first round of data collection and at most M + 1 slots in subsequent rounds, where M is the lower bound to complete one round of convergecast and H is the maximum height of the data gathering trees. Our schedule does not require any node to store more than two packets. In the next step, we consider interference among simultaneous transmissions and allocate multiple frequency channels to ensure interference below a certain threshold. The problem of minimizing the frequency channels while maintaining SINR above the desired value is reduced to a semidefinite programming relaxation. In our simulation, the time for the first round of convergecast is much lower than M + H + 1 (closer to M + 1), and the channel allocation algorithm requires either optimal or just one more than the optimal number of channels.

关键词： Wireless sensor network (WSN) TDMA scheduling Data collection integer linear programming Semidefinite programming

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Optimal path planning for unmanned aerial vehicles in power line inspection in rechargeable scenario

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PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART B-JOURNAL OF ENGINEERING MANUFACTURE 2024年

作者： Zhang, Weihao Chen, Bojian Chen, Zhuolei Li, Zhezhou Han, Tengfei Wu, Wenbin Zhang, Xiaoqiang State Grid Fujian Elect Power Res Inst Fuzhou Peoples R China Civil Aviat Flight Univ China Inst Elect & Elect Engn 46 Nanchang Rd Guanghan 618307 Peoples R China Beihang Univ Sch Elect & Informat Engn Beijing Peoples R China

To address the issue that a single charge of UAVs (Unmanned Aerial Vehicles) do not satisfy task requirements, this paper proposes a solution involving the deployment of charging stations in the mission area. An energy-efficient path planning method is designed for UAVs with charging stations, which simultaneously determines the deployment locations and quantities of charging stations. The method formulates the energy optimization path planning problem of UAVs as an integer linear programming and an algorithm based on greedy strategy is designed for solving the model. A numerical example including simulations across various scenarios demonstrate that the proposed method can search a more energy-efficient paths compared to single-agent multi-sortie schemes with a greedy strategy. This research contributes to the development of intelligent and autonomous UAV systems for power line inspection, enhancing grid reliability and safety.

关键词： Rechargeable UAVs optimal path planning integer linear programming power line inspection greedy strategy

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Optimizing Shared E-Scooter Operations Under Demand Uncertainty: A Framework Integrating Machine Learning and Optimization Techniques

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IEEE ACCESS 2024年 12卷 26957-26977页

作者： Saum, Narith Sugiura, Satoshi Piantanakulchai, Mongkut Hokkaido Univ Div Engn & Policy Sustainable Environm Sapporo Hokkaido 0600808 Japan Thammasat Univ Sirindhorn Int Inst Technol Sch Civil Engn & Technol Pathum Thani 12121 Thailand

The emergence of dockless shared e-scooters as a new form of shared micromobility offers a viable solution to specific urban transportation problems, including the first-mile-last-mile issue, parking constraints, and environmental emissions. However, this sharing service faces several challenges in daily operation, particularly related to demand volatility, battery recharging, maintenance, and regulations, owing to their trip and physical characteristics. Therefore, this study proposed a new data-driven rebalancing framework for dockless shared e-scooters that incorporates demand and variance prediction, and Monte Carlo sampling to simulate the expected demand. Thus, demand uncertainty and the collection of low-battery and broken e-scooters were included in the rebalancing formulation to minimize user dissatisfaction and operating costs. Rebalancing optimization is an NP-hard problem;in this study, the small-size problem was solved using the integer linear programming (ILP) solver GNU linear programming Kit, and the large-size problem was solved using the proposed hybrid ant colony optimization-ILP algorithm (ACO-ILP). This framework was evaluated on a real-world dataset from Minneapolis, Minnesota, which demonstrated that the demand and variance prediction efficiently allocated the uncertainty while reducing the overall uncertainty, leading to shorter driving distances and lower rebalancing costs relative to baseline cases.

关键词： Shared e-scooter integer linear programming ant colony optimization gradient boosting SGARCH demand uncertainty

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PangeBlocks: customized construction of pangenome graphs via maximal blocks

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BMC BIOINFORMATICS 2024年第1期25卷 1页

作者： Cartes, Jorge Avila Bonizzoni, Paola Ciccolella, Simone Della Vedova, Gianluca Denti, Luca Univ Milano Bicocca Dept Informat Syst & Commun Viale Sarca I-20126 Milan Italy Comenius Univ Fac Math Phys & Informat Dept Appl Informat Mlynska Dolina F1 Bratislava 84248 Slovakia

BackgroundThe construction of a pangenome graph is a fundamental task in pangenomics. A natural theoretical question is how to formalize the computational problem of building an optimal pangenome graph, making explicit the underlying optimization criterion and the set of feasible solutions. Current approaches build a pangenome graph with some heuristics, without assuming some explicit optimization criteria. Thus it is unclear how a specific optimization criterion affects the graph topology and downstream analysis, like read mapping and variant *** this paper, by leveraging the notion of maximal block in a Multiple Sequence Alignment (MSA), we reframe the pangenome graph construction problem as an exact cover problem on blocks called Minimum Weighted Block Cover (MWBC). Then we propose an integer linear programming (ILP) formulation for the MWBC problem that allows us to study the most natural objective functions for building a graph. We provide an implementation of the ILP approach for solving the MWBC and we evaluate it on SARS-CoV-2 complete genomes, showing how different objective functions lead to pangenome graphs that have different properties, hinting that the specific downstream task can drive the graph construction *** show that a customized construction of a pangenome graph based on selecting objective functions has a direct impact on the resulting graphs. In particular, our formalization of the MWBC problem, based on finding an optimal subset of blocks covering an MSA, paves the way to novel practical approaches to graph representations of an MSA where the user can guide the construction.

关键词： Pangenome graphs Variation graph construction integer linear programming Maximal blocks

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An ILP approach for tactical flight rescheduling during airport access mode disruptions

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INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH 2024年第3期31卷 1426-1457页

作者： Scozzaro, Geoffrey Mancel, Catherine Delahaye, Daniel Feron, Eric Univ Toulouse ENAC 7 Ave Edouard Belin F-31400 Toulouse France King Abdullah Univ Sci & Technol Thuwal 23955 Saudi Arabia

Airport access mode disruptions, such as a subway shutdown, threaten the whole passenger door-to-door journey. When such a disruptive event occurs, knowledge of passengers' delays would help the airport operation centre to decide if a departure flight should be delayed. This paper proposes a tactical flight rescheduling at an airport to minimise the number of stranded passengers while considering operational constraints. An integer linear programming formulation of the problem is presented. Constraints such as terminal capacities, maximal runway throughput, minimum turnaround time or minimum transfer time for connecting passengers are considered. An exact and heuristic resolution is proposed and compared to a study case around Paris-Charles de Gaulle airport. The new schedule satisfies the operational constraints and reduces up to 60% of the number of stranded passengers with moderate deviation from the initial planning.

关键词： air transportation flight rescheduling passengers access mode disruptions integer linear programming

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Analysis of the location problem of emergency attendance teams for a railroad through optimization

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INTERNATIONAL TRANSACTIONS IN OPERATIONAL RESEARCH 2024年第6期31卷 4363-4399页

作者： Troian, Rodrigo Santos, Gisele Tessari Campos, Rodrigo Alexandre Celestino IETEC Inst Technol Educ Dept Engn & Management Proc & Syst BR-30140138 Belo Horizonte MG Brazil IBMEC Brazilian Inst Capital Markets Dept Ind Engn BR-30130130 Belo Horizonte MG Brazil

Rail operators worldwide are seeing an increase in demand for services, driven by expanding global trade and the use of export commodities. Punctual service in a train stopped on the railroad is extremely important since the delay in service significantly impacts performance, asset utilization, and railroad productivity. The present work addresses the development and the solution of an optimization model for locating railway service teams that serve locomotives that need emergency maintenance on a Brazilian railway. Additionally, a hypercube model was solved to estimate several performance measures that assist in decision-making. From the result analysis of different scenarios, it was found that the optimized maintenance teams' location provides superior results to the current ones considering the same resources. Also, it was possible to increase the coverage with double attendance in the studied system, monitoring different indicators such as attendance teams' average system travel time and workload.

关键词： railway optimization service teams integer linear programming double cover model

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Integrated Planning Approach for Optimizing Tower Crane and Truck Locations in Modular Integrated Construction

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JOURNAL OF CONSTRUCTION ENGINEERING AND MANAGEMENT 2024年第9期150卷

作者： Wang, Roy Dong Zayed, Tarek Eltoukhy, Abdelrahman E. E. Wu, Hengqin Hong Kong Polytech Univ Dept Bldg & Real Estate Kowloon Hong Kong Peoples R China Khalifa Univ Management Sci & Engn Dept Abu Dhabi U Arab Emirates

Tower crane layout planning (TCLP) is key to ensure the safety and productivity of construction projects. Previous studies on TCLP mainly focused on the typical in situ construction method, however, overlooking modular integrated construction (MiC). This study aims to develop an integrated planning approach for optimizing the locations of tower cranes and trucks for MiC across the entire construction site. This approach consists of four objective components. First, identifying potential locations for cranes and trucks by adopting a gridding method and an intersection examination algorithm. Second, estimating the crane operation duration. Third, optimizing the crane and truck locations by developing an integer linear programming (ILP) model while considering various constraints, such as the demand fulfillment, the crane's lifting capacity, and the multiple truck parking areas. Lastly, optimizing the distance between cranes to avoid crane blocking on site. The proposed approach is validated via three high-rise residential MiC projects. The results achieve 19.4%-37.9% reductions in cranes' operation durations, as well as carbon emissions from the original plan. Compared with another existing TCLP method made from limited predefined layout plans, a 29.4% improvement is observed. Moreover, three aspects to extend the application of the approach are discussed: (1) the multiple tower crane layout scenario, (2) the impact of the number of truck points, and (3) the trade-offs between computing effectiveness and performance. The approach realizes the objective of TCLP decision-making for multi-crane multitruck MiC throughout the whole construction site. Construction practitioners can use this approach for decision-making which helps enhance the effectiveness of their tower crane layout designs.

关键词： Modular integrated construction (MiC) Tower crane layout planning (TCLP) Truck location integer linear programming

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