Multi-resource collaborative scheduling problem of automated terminal considering the AGV charging effect under COVID-19.

Since the COVID-19 ravaged the global terminals, the Automated Container Terminal (ACT) has become one of important approach to promote the stronger quick response capacity to deal with the uncertainty that COVID-19 brought to the terminal. This research takes Automated Guided Vehicle (AGV) and their effects into account the multi-resource collaborative scheduling model to tradeoff ACT operational efficiency and energy savings. Firstly, the dual-cycle strategy of QC and the pooling strategy of AGV are given, which coordinates the scheduling of Quay Cranes (QCs), Yard Cranes (YCs) and other equipment. Furthermore, a multi-resource collaborative scheduling optimization model is proposed which roots from the principle of the Blocking-type Hybrid Flow Shop Problem (B-HFSP) with the objectives of minimizing the makespan of QC and the transportation energy consumption. And simultaneously, a mixed algorithm SA-GA is designed for solving this mixed integer programming model by an optimizing effect of Simulated Annealing on Genetic algorithms. Numerical experiments show that the model in this research is effective. The convergence of SA-GA is effective for small-scale cases and superior for large-scale cases. Considering both goals of high efficiency and energy saving, the Pareto solution set and collaborative scheduling solution take a priority to ensure that the bottlenecked QC runs efficiently. Here and now the average idle rate of QC is about [14%, 35%] lower than that of other equipment. The collaborative scheduling model constructed above not only has reference value for other multi-device and multi-stage scheduling problem, but also enhance the integrated decision-making ability of the ACT in the post-epidemic era.

Analysis on the stability and evolutionary trend of the symbiosis system in the supply chain of fresh agricultural products.

In order to increase the stability of fresh agricultural product supply chain, farmers and enterprises need to evolve into a symbiotic system of supply chain. At the present stage, symbiotic relations and evolutionary trends in a symbiotic system for fresh agricultural product supply chains lack quantitative methods for determining symbiotic criteria. In the sense of quantification -oriented criteria, symbiotic systems for fresh agricultural product supply chains are defined, and an improved stationary state analysis method is proposed. Three key steps in this method are quantifying a symbiotic energy model with an evaluation model of ecological carrying capacity, setting up a system evolution model based on the logistic growth function, and verifying the symbiotic system's singularity and phase transition boundary by Lyapunov indirect method. MATLAB numerical simulation shows that types of singularity and the phase transition boundary of symbiotic system are divided effectively. And in both conditions, infinite exponential growth and convergence to steady state, the mutualism mode is the optimal choice for the symbiotic system we defined, symbiotic relations between farmers and cooperative companies are stable and long-term at this time. Those conclusions provide a reference approach to enhance the overall prospective benefits to the fresh agricultural products supply chain.