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To reveal the profound impact of dispatching strategy and route of autonomous mobile robot (AMR) on scheduling in the flexible job shop with AMRs, this study presents the bi-level programming model for integrated scheduling with machines and AMRs (ISMV), subdividing distributed shared dispatching strategy (DSDS) and following dispatching strategy (FDS) for AMRs. The integrated scheduling model is developed at the upper level with the objective of minimizing the makespan, and the AMR conflict-free route planning (CFRP) model is formulated at the lower level to minimize travel time. To solve the model, a novel algorithmic framework (SLGA-D) composed of the self-learning genetic algorithm (SLGA) and Dijkstra with time window (DijkstraTW) is designed. The SLGA is formed by embedding the Q-learning into genetic algorithm to intelligently adjust crossover probability and mutation probability. Several experiments are implemented to validate the SLGA-D and the model proposed in this study. The results of experiments prove that reinforcement learning mechanism within Q-learning successfully enhances the global search ability of the algorithm, and production scheduling and distribution route are optimized synergistically by the model. Sensitivity analyses reveal that, as the number of AMRs rises, the makespan tends to stabilize after decreasing rapidly to a threshold value. Once the number of AMRs exceeds a certain threshold ( w = 5 in this study), it is not significant to shorten the makespan by continuing to invest AMRs. When the number of production tasks to be processed does not exceed the number of AMRs, following dispatching strategy of AMR is more favorable; conversely, distributed shared dispatching strategy is superior. The results provide guideline and inspiration for managers who are committed to manufacturing schedule and control. [ABSTRACT FROM AUTHOR]

The convergency and diffusion behaviours of truck information derived from BeiDou trajectory data are extremely useful in improving the capacity of logistics critical roads (LCR) in industrial parks. In this paper, a novel dynamic identification method of LCR is proposed for traffic refined organization in industrial parks. The structural importance method is built in the first step to assess the theoretical importance of road network structure. The logistics attractiveness of the road is then measured using a business circle model with built environment and truck behaviour factors. In the third step, the real‐time road selectivity is calculated using the K‐Average Nearest Neighbour Density‐Based Spatial Clustering of Applications with Noise (KANN—DBSCAN) algorithm to assess road vulnerability. Finally, LCR are identified by solving the road criticality based on the aforementioned parameters. The method is validated by comparing the predicted LCR with the factual LCR in a case study of Hongqi town and relative BeiDou data. The conformity of the proposed method with reality is > 85%. The authors reveal some rules at various times: Logistics factors are more important in LCR in industrial parks. LCR with heavy passenger traffic have a significant tide, and those with heavy freight traffic are strongly correlated with production plans. [ABSTRACT FROM AUTHOR]

Network-wide maintenance lacks strong theoretical support and practical cases. However, research on this topic has entered an extensive exploratory stage; for example, new network design methods are being sought, and successful practices from traditional maintenance by line and by profession are being incorporated. This paper proposes a novel set-covering model with the variable coverage radius for the maintenance network of urban rail transit systems in the context of network-wide maintenance. The concepts of network-wide maintenance follow principles that are similar to those of bio-geography-based optimization (BBO), i.e., patterns of migration, variation, and extinction of different populations in different habitats. Therefore, a BBO algorithm is implemented with combinatorial optimization programming. Experiments from Changchun city in China show that the proposed model and algorithm are effective in fulfilling network-wide requirements through a direct tradeoff between the coverage radius and maintenance response time. In addition, the maintenance capacity and variable coverage radius of each maintenance point influence both the maintenance timeliness and resource utilization of maintenance units., 1. Introduction As of December 31, 2018, according to a statistical analysis of urban rail transit lines, 169 urban lines in 32 cities in mainland China were in operation, having [...]

Highway passenger transport based express parcel service (HPTB-EPS) is an emerging business that uses unutilised room of coach trunk to ship parcels between major cities. While it is reaping more and more express market, the managers are facing difficult decisions to design the service network. This paper investigates the HPTB-EPS network design problem and analyses the time-space characteristics of such network. A mixed-integer programming model is formulated integrating the service decision, frequency, and network flow distribution. To solve the model, a decomposition-based heuristic algorithm is designed by decomposing the problem as three steps: construction of service network, service path selection, and distribution of network flow. Numerical experiment using real data from our partner company demonstrates the effectiveness of our model and algorithm. We found that our solution could reduce the total cost by up to 16.3% compared to the carrier's solution. The sensitivity analysis demonstrates the robustness and flexibility of the solutions of the model., 1. Introduction Highway passenger transport based express parcel service (HPTB-EPS) is a recently emerging business model for highway passenger transportation companies to fully utilise their transport capacity so as to [...]