서울시 ‘따릉이’를 중심으로

학위논문(석사) -- 서울대학교대학원 : 공과대학 건설환경공학부, 2022.2. 황준석.더욱 합리적이고 인간적인 공공자전거 서비스를 제공하기 위해서 공공자전거가 시스템 더 효율적으로 운영되고 서비스 이용자 만족도를 높이도록 한 가지 자전거 재배치 경로 최적화 목적으로 공공자전거 재배치 최적화 모델을 제시하였다. 기존 재배치 모델들의 속도 느림, 정확도 낮음 등 한계점을 개선하기 위해서, 본 논문에서 GA와 ACO 알고리즘을 조합돼서 GAACO-BSP(a Genetic Hybrid Ant Colony Optimization Algorithm for Solving Bike-sharing Scheduling Problem) 알고리즘을 개발하였다. 그리고 성능 향상시키기 위하여 GA 수행횟수 제어 함수를 수립하여 두 알고리즘을 동적으로 연결하였다. 우선 GA가 스케줄링 가능한 초기해를 구하고, 그 다음으로 GA 수행횟수 제어 함수를 통해 최적 전환 시기를 파악해서 동적으로 ACO으로 전환한다. ACO가 GA에게서 초기화 필요한 페로몬을 얻고 최종 최적해를 찾는 것이다. 서울시 공공자전거 따릉이 사례로 결과를 검증하여, GAACO-BSP은 전통 단일 알고리즘보다 뛰어난 성능 우세로 대규모 자전거 시스템에 적용하고 더 짧은 시간 만에 재배치 거리를 더 많이 줄였다. 실험을 통해 GAACO-BSP가 실제 도시 공공자전거 시스템에서 적용할 수 있다는 것을 알 수 있다.To improve the service efficiency and customer satisfaction degree of public bicycle, a bike-sharing scheduling model is proposed, which aims to get the shortest length of the bicycle scheduling. To address the slow solution speed of the existing algorithms, which is not conducive to real-time scheduling optimization, this paper designed a Genetic Hybrid Ant Colony System Algorithm for Solving Bike-sharing Scheduling Problem (GAACS-BSP). Genetic algorithm was used to search initial feasible scheme， which was used to initialize pheromone distribution of ant colony algorithm. It solved problem of lack initial pheromone, to improve the efficiency of bike-sharing scheduling tasks. There also proposed a genetic algorithm control function to control the appropriate combination opportunity of the two algorithms. Finally, the results show that compared with GA or ACS, it is more suitable for solving the problem of large-scale bike-sharing scheduling tasks, which shortens the scheduling distance in a short period.제 1 장 서 론 1 1.1. 연구의 배경 1 1.2. 연구의 내용 2 제 2 장 선행 연구 3 2.1. 기존 공공자전거 재배치에 관한 연구 3 2.2. 기존 GA-ACO 융합 알고리즘 5 제 3 장 모델 구축 방법론 8 3.1. BSP 문제의 수학적 해석 8 3.2. BSP 해결을 위한 GAACO-BSP 11 3.2.1. 기본 생각 11 3.2.2. 전체 프레임워크 11 제 4 장 GAACO-BSP 알고리즘 13 4.1. GA 부분의 규칙 14 4.1.1. 인코딩 방식 및 초기화 14 4.1.2. 선택 15 4.1.3. 교차 및 변이 15 4.1.4. 정지 조건 및 전환 16 4.2. ACO 부분의 규칙 17 4.2.1. ACO 초기화 17 4.2.2. 경로 선택 규칙 18 4.2.3. Pheromone 농도 조절 18 4.3. 알고리즘 흐름도 20 제 5 장 실험 및 결과 21 5.1. 데이터 전처리 21 5.2. 지역센터(배송팀) 재구분 26 5.3. 재배치 전략방안 도출 29 5.3.1. 수요현황 분석 29 5.3.2. 재배치 최적화 방안 도출 32 제 6 장 결 론 38 참고 문헌 41석

Tackling a VRP challenge to redistribute scarce equipment within time windows using metaheuristic algorithms

This paper reports on the results of the VeRoLog Solver Challenge 2016–2017: the third solver challenge facilitated by VeRoLog, the EURO Working Group on Vehicle Routing and Logistics Optimization. The authors are the winners of second and third places, combined with members of the challenge organizing committee. The problem central to the challenge was a rich VRP: expensive and, therefore, scarce equipment was to be redistributed over customer locations within time windows. The difficulty was in creating combinations of pickups and deliveries that reduce the amount of equipment needed to execute the schedule, as well as the lengths of the routes and the number of vehicles used. This paper gives a description of the solution methods of the above-mentioned participants. The second place method involves sequences of 22 low level heuristics: each of these heuristics is associated with a transition probability to move to another low level heuristic. A randomly drawn sequence of these heuristics is applied to an initial solution, after which the probabilities are updated depending on whether or not this sequence improved the objective value, hence increasing the chance of selecting the sequences that generate improved solutions. The third place method decomposes the problem into two independent parts: first, it schedules the delivery days for all requests using a genetic algorithm. Each schedule in the genetic algorithm is evaluated by estimating its cost using a deterministic routing algorithm that constructs feasible routes for each day. After spending 80 percent of time in this phase, the last 20 percent of the computation time is spent on Variable Neighborhood Descent to further improve the routes found by the deterministic routing algorithm. This article finishes with an in-depth comparison of the results of the two approaches

Book of abstracts of the 24th Euro Working Group on Transportation Meeting

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Systems Engineering: Availability and Reliability

Current trends in Industry 4.0 are largely related to issues of reliability and availability. As a result of these trends and the complexity of engineering systems, research and development in this area needs to focus on new solutions in the integration of intelligent machines or systems, with an emphasis on changes in production processes aimed at increasing production efficiency or equipment reliability. The emergence of innovative technologies and new business models based on innovation, cooperation networks, and the enhancement of endogenous resources is assumed to be a strong contribution to the development of competitive economies all around the world. Innovation and engineering, focused on sustainability, reliability, and availability of resources, have a key role in this context. The scope of this Special Issue is closely associated to that of the ICIE’2020 conference. This conference and journal’s Special Issue is to present current innovations and engineering achievements of top world scientists and industrial practitioners in the thematic areas related to reliability and risk assessment, innovations in maintenance strategies, production process scheduling, management and maintenance or systems analysis, simulation, design and modelling

Vehicle sharing and workforce scheduling to perform service tasks at customer sites

Most of the research done in the Vehicle Routing Problem (VRP) assumes that each driver is assigned to one and only one vehicle. However, in recent years, research in the VRP has increased its scope to further accommodate more restrictions and real-life features. In this line, vehicle sharing has grown in importance inside large companies with the aim of reducing vehicle emissions. The aim of this thesis is to study different situations where sharing vehicles brings an improvement. Our main study focuses on developing a framework that is capable of assigning different workers to a common vehicle, allowing them to share their journey. We introduce a mathematical programming model that combines the vehicle routing and the scheduling problem with time constraints that allows workers to share vehicles to perform their activities. To deal with bigger instances of the problem an algorithm capable of solving large scenarios needs to be implemented. A multi-phase algorithm is introduced, Phase 1 allows us to solve the non-sharing scheduling/routing problem whose aim is to find the best schedule for workers. Phase 2 will merge the allocated workers into common vehicles when possible, while Phase 3 is the improvement procedure of the algorithm. The algorithm is tested in three different settings; using workers as drivers, hiring dedicated drivers, and allowing workers to walk between jobs when possible. Results show that sharing vehicles is practicable under specific conditions, and it is able to reduce both the number of vehicles and the total distance, without affecting the performance of workers schedule

Hybrid meta-heuristics for combinatorial optimization

Combinatorial optimization problems arise, in many forms, in vari- ous aspects of everyday life. Nowadays, a lot of services are driven by optimization algorithms, enabling us to make the best use of the available resources while guaranteeing a level of service. Ex- amples of such services are public transportation, goods delivery, university time-tabling, and patient scheduling. Thanks also to the open data movement, a lot of usage data about public and private services is accessible today, sometimes in aggregate form, to everyone. Examples of such data are traffic information (Google), bike sharing systems usage (CitiBike NYC), location services, etc. The availability of all this body of data allows us to better understand how people interacts with these services. However, in order for this information to be useful, it is necessary to develop tools to extract knowledge from it and to drive better decisions. In this context, optimization is a powerful tool, which can be used to improve the way the available resources are used, avoid squandering, and improve the sustainability of services. The fields of meta-heuristics, artificial intelligence, and oper- ations research, have been tackling many of these problems for years, without much interaction. However, in the last few years, such communities have started looking at each other’s advance- ments, in order to develop optimization techniques that are faster, more robust, and easier to maintain. This effort gave birth to the fertile field of hybrid meta-heuristics.openDottorato di ricerca in Ingegneria industriale e dell'informazioneopenUrli, Tommas

Shared Mobility Optimization in Large Scale Transportation Networks: Methodology and Applications

abstract: Optimization of on-demand transportation systems and ride-sharing services involves solving a class of complex vehicle routing problems with pickup and delivery with time windows (VRPPDTW). Previous research has made a number of important contributions to the challenging pickup and delivery problem along different formulation or solution approaches. However, there are a number of modeling and algorithmic challenges for a large-scale deployment of a vehicle routing and scheduling algorithm, especially for regional networks with various road capacity and traffic delay constraints on freeway bottlenecks and signal timing on urban streets. The main thrust of this research is constructing hyper-networks to implicitly impose complicated constraints of a vehicle routing problem (VRP) into the model within the network construction. This research introduces a new methodology based on hyper-networks to solve the very important vehicle routing problem for the case of generic ride-sharing problem. Then, the idea of hyper-networks is applied for (1) solving the pickup and delivery problem with synchronized transfers, (2) computing resource hyper-prisms for sustainable transportation planning in the field of time-geography, and (3) providing an integrated framework that fully captures the interactions between supply and demand dimensions of travel to model the implications of advanced technologies and mobility services on traveler behavior.Dissertation/ThesisDoctoral Dissertation Civil, Environmental and Sustainable Engineering 201

Scientific research trends about metaheuristics in process optimization and case study using the desirability function

This study aimed to identify the research gaps in Metaheuristics, taking into account the publications entered in a database in 2015 and to present a case study of a company in the Sul Fluminense region using the Desirability function. To achieve this goal, applied research of exploratory nature and qualitative approach was carried out, as well as another of quantitative nature. As method and technical procedures were the bibliographical research, some literature review, and an adopted case study respectively. As a contribution of this research, the holistic view of opportunities to carry out new investigations on the theme in question is pointed out. It is noteworthy that the identified study gaps after the research were prioritized and discriminated, highlighting the importance of the viability of metaheuristic algorithms, as well as their benefits for process optimization

Balancing the trade-off between cost and reliability for wireless sensor networks: a multi-objective optimized deployment method

The deployment of the sensor nodes (SNs) always plays a decisive role in the system performance of wireless sensor networks (WSNs). In this work, we propose an optimal deployment method for practical heterogeneous WSNs which gives a deep insight into the trade-off between the reliability and deployment cost. Specifically, this work aims to provide the optimal deployment of SNs to maximize the coverage degree and connection degree, and meanwhile minimize the overall deployment cost. In addition, this work fully considers the heterogeneity of SNs (i.e. differentiated sensing range and deployment cost) and three-dimensional (3-D) deployment scenarios. This is a multi-objective optimization problem, non-convex, multimodal and NP-hard. To solve it, we develop a novel swarm-based multi-objective optimization algorithm, known as the competitive multi-objective marine predators algorithm (CMOMPA) whose performance is verified by comprehensive comparative experiments with ten other stateof-the-art multi-objective optimization algorithms. The computational results demonstrate that CMOMPA is superior to others in terms of convergence and accuracy and shows excellent performance on multimodal multiobjective optimization problems. Sufficient simulations are also conducted to evaluate the effectiveness of the CMOMPA based optimal SNs deployment method. The results show that the optimized deployment can balance the trade-off among deployment cost, sensing reliability and network reliability. The source code is available on https://github.com/iNet-WZU/CMOMPA.Comment: 25 page