With the economic globalization continuing to advance, coastal port cities have enjoyed increasingly prominent status and roles as the link between the sea and the land and an important window of foreign trade and exchanges. However, port cities, while embracing rapid development, have also produced a significant impact on natural resources and the ecological environment. Ecological environment protection has become a must-consider factor for sustainable development of port cities. To secure coordinated and sustainable development of ports and cities, this paper utilizes the system dynamics theory and approaches the subject from driver analysis. In the traditional port-city collaboration system model, indicators of ecological perspectives such as land resources and environmental protection are introduced to build a dynamic model for the spatial evolution system of port-city coupling system based on ecological protection, and the dynamic mechanism of port-city spatial relation evolution is analyzed in depth with a case study of Dongdu Port Area of Xiamen Port. The model’s simulation results show that from an ecological perspective, the spatial distance between the port and the city is critical to their sustainable and coordinated development. Only after the port-city spatial distance increases moderately can the development efficiency of the port-city system welcomes a relatively significant increase. Managing the port-city distance well has a significant driving effect on capacity enhancement of the port and economic development of the city. This provides a theoretical reference for further studies on port-city coordinated and sustainable development and provides constructive suggestions for the government to make relevant decisions.

Ports play an important role in maritime cluster. In this study, the effect of maritime cluster on port production efficiency is discussed. First, the maritime cluster was divided into three classes: transportation & warehousing class (T&W), agent & technical class (A&T), and advanced class (Advan). Second, the effect of each part on the port production efficiency was theoretically assessed. Then, based on the 2001–2018 panel data from the Bohai Bay, China, the effects of shipping (T&W), shipping agency (A&T) and ship design (Advan) on total factor productivity (TFP) of the port were analyzed using a multilevel regression model. The empirical results indicated that the increase in the shipping industry and the shipping agency with low-added value and low knowledge density, participated in port production activities, promoting the port TFP. The ship design industry with high added value and high knowledge density did not participate in port activity, and did not directly affect the port TFP, but positively moderated the port TFP. In addition, the maritime cluster in a recession is proven to inhibit port TFP. These findings provided enlightenment for the government to improve the efficiency of port production, and a theoretical basis to merge the development of maritime cluster and port system.

As terrestrial resources become increasingly scarce, the exploration and utilization of marine resources have become crucial for ensuring a stable resource supply. A maritime A-Frame is a specialized lifting mechanism mounted on the stern of a vessel, designed for deploying and retrieving heavy loads during subsea exploration. Real-time monitoring of the stress of A-Frames is essential for identifying potential failures and preventing accidents. This paper presents a stress-monitoring campaign conducted on a maritime A-Frame during a deep-sea mining project in the South China Sea. Fiber Bragg Grating (FBG) strain sensors were installed on the A-Frame to measure its stress responses throughout the deep-sea mining operation. The stress variations observed during the deployment and retrieval of a deep-sea mining vehicle were analyzed. The results indicate that the stress caused by the swinging motion of the A-Frame was significantly higher than that generated by the lifting and deployment of the mining equipment. Additionally, a finite element model (FEM) of the A-Frame was developed to estimate the stress of the hot spots by integrating the measured strain data. The analysis confirmed that the maximum stress experienced by the A-Frame was well below the allowable threshold, indicating that the structure had sufficient strength to withstand operational loads. In addition, the swing angle of the A-Frame significantly affects the stress value of the A-Frame, while lifting the mining vehicle has a very slight effect. Thus, it is advisable to accelerate the deployment and retrieval speeds of the mining vehicle and minimize the outward swing angle of the A-Frame. These findings provide valuable insights for optimizing the design and ensuring the safe operation of maritime A-Frames in deep-sea mining exploration.