The wave added resistance is calculated based on full-scale ship navigation data, using two methods: numerical calculation and empirical formula, and the calculation accuracies achieved by the two methods are investigated. A bulk carrier is selected for illustration. The ship type information of the bulk carrier is collected. Based on the ship type information, the wave added resistance response curve is calculated; The navigation monitoring data of bulk carriers are collected, and the corresponding wave added resistance response curves for each sampled data are calculated using Python programming. The corresponding wave added resistance values are obtained according to the wave height and wave period of each sampled data usingITTC (International Towing Tank Conference) dual parameter wave spectrum; Then, based on the ISO 15016:2015 regulations, wind, waves, temperature, and water density are corrected, and the shaft power is corrected to the ideal calm water power through wave added resistance correction, water temperature correction, wind resistance correction, etc. Finally, the correction results are compared with the resistance analysis results of the fast model test for bulk carriers, verifying that the SNNM(SHOPERA-NTUA-NTU-MARIC) method is better corelated to the wave added resistance on the actual ship than the slice method used.
A summary of recent researches and achievements in the field of two types of ship wind-assisted propulsion devices-rotor sails and arc-shaped sails are summarized. The literature on the subject is reviewed. The scopes and the methodologies of the works are studied. The contributions of these works to the field are analyzes. The review indicates that the aerodynamic performance and its influencing factors of rotor sails and arc-shaped sails have been researched comprehensively. The development of research methods such as model testing and numerical calculations has reached a mature stage, with numerical calculations generally demonstrating high accuracy in most cases. Further in-depth research on the numerical calculation of aerodynamic performance for rotor sails at high Reynolds numbers is warranted.
The impact of errors in measurements of swing amplitude, cycloid length, and arm of force on the calculation results of the metacentric height hGM of the ship in inclining tests is studied. The 5 000 ton barge “Shipping Barge 1” is analyzed for illustration. The influencing factors for the ship’s inclining test are analyzed. A mathematical model based on error propagation theory is built for analyzing the influence of measurement errors in swing amplitude, cycloid length, and arm of force on hGM under the test conditions, The sensitivity analysis is conducted to clarify the degree of influence of each factor. The results are verified through calculation of some typical ship cases. The research results indicate that the swing error has the greatest impact on the calculation results of hGM; The larger the hGM, the greater the calculation error of hGM the swing amplitude change causes.
This paper proposes a distributed energy storage control strategy for the coordination of distributed energy storage in ship integrated electric propulsion systems containing AC and DC bus-bars. Simulation models of the parts of the ship’s integrated electric propulsion system are built, including power generation system, energy storage system, etc.; A distributed energy storage control strategy is designed for the system, which achieves the automation of the energy storage system by collecting information such as bus voltage and energy storage status; A system simulation model of the ship’s integrated electric propulsion system is constructed and operated. The simulation results show that the fluctuation of DC bus voltage is less than 2%. The system’s AC and DC bus voltage can meet the operational requirements. The distributed energy storage management method proposed in this paper can effectively manage energy storage systems and achieve stable operation.
To address the safety risks of leakage, phase imbalance, and explosion associated with ammonia fuel injection operations, for the injection scenario of a certain type of ammonia powered tugboat tanker truck, a collaborative plan for process optimization and risk prevention is developed. Based on CFD (Computational Fluid Dynamics) numerical simulation (SST k-ω turbulence model), the diffusion law of ammonia leakage is quantified, and a three-level dynamic safety control zone is designed to solve the multiphase flow balance problem of liquid ammonia injection. By means of a nitrogen dual loop purging system with real-time monitoring technology based on laser absorption spectroscopy, a leak prevention and control closed-loop mechanism is formed. The research results indicate that this scheme can effectively control the risks of leakage, explosion, and low temperature during the process of liquid ammonia refueling, providing a highly applicable and safe technological paradigm for ammonia fuel ship refueling, and supporting the low-carbon transformation of the shipping industry.
This paper Explores the application of RAG (Retrieval-Augmented Generation) technology in building a large-scale shipping professional knowledge base, providing support for the intelligent development of the shipping industry. The principle of RAG technology is introduced systematically. The limitations of traditional RAG knowledge bases in text slicing, retrieval accuracy, and global understanding are analyzed. Advanced solutions such as introducing reordering models, database MPC (Multi-Process Communication) Server architecture, and super large context models are proposed to establish a shipping professional knowledge base. The research results indicate that the construction of a shipping professional knowledge base based on the RAG big model can significantly enhance the information retrieval and knowledge generation capabilities in the shipping professional field, providing strong support for the digital transformation of the shipping industry.
In order to improve the operational management level and asset utilization efficiency of container asset management enterprises, considering the uncertainty of the behavior in returning container upon lease termination and the influence of other internal and external factors, a predictive analysis is conducted on the behavior of returning container upon lease termination. An intelligent prediction model is developed based on customer historical data and comprehensive variables such as regional container return limits and monthly container return limits of ports for particular container types. The container return volume is predicted through specific calculation methods. The practical application results have proved that the model can perform prediction and analysis of action of returning container upon lease termination, assist container asset management enterprises in predicting the future evolution trend of lease termination, help them adjust management and operation strategies in a timely manner, and improve operational management efficiency and asset utilization.
In order to meet the demand for intelligent development in the field of tunnel engineering traffic monitoring in China, a traffic monitoring platform based on microservice architecture is designed to address the problems of low emergency rescue efficiency, insufficient intelligent control, and inadequate data analysis capabilities of traditional monolithic traffic monitoring systems. The traffic monitoring platform adopts a layered architecture design and modular design. By integrating GIS (Geographic Information System), video, Internet of Things, digital twins, and data governance services, sub platforms such as road network monitoring, tunnel monitoring, and emergency response are built to connect rescue parties quickly, improve the emergency rescue efficiency and enhance the intelligent control. The system can predict traffic situations through big data analysis and effectively improve the platform’s intelligence level. The platform has been deployed in Qinghai and Chongqing, and the results show that it can significantly improve the intelligence level of traffic management through full factor data perception and full process business control.
Regions in Shanghai are classified based on their characteristics in terms of usage—production area, living quarter or ecological zone. The land use distribution pattern and its evolution characteristic in Shanghai in the period of 2010—2020 are studied from two aspects of spatial layout and quantitative structure using the land use transition matrix and land use dynamic degree. The research shows the facts as follows: The change of space distribution in Shanghai was significant in the period of 2010—2020. The area of ecological zone was relatively small, mainly covered by Shanghai Jiuduansha Wetland National Nature Reserve. However, it had expanded and further expansion is expected. The area of ecological production space and production ecological space reduced in the process of development, and the living and production space expanded. Among four types of spaces, the transition from production ecological space to living production space accounted for the largest proportion, the conversion from ecological production space to production ecological space follow. The ecological space had been transferred out to some extent in the 10 years, but the amount of transfer in is larger, so the overall area has increased. As for the periods from 2010 to 2015 and from 2015 to 2020, the ecological space area showed increasing trends in both periods. The area of ecological production space and production ecological space continued to decrease, while the area of living and production space continued to increase. The intensity of overall land use change was at a low level in both periods.
The linear engineering project plan is a strip-shaped design drawing with a large aspect ratio. It requires dozens of sheets when printed on the standard A-series size paper, which means a large amount of manual labor. To improve the drafting efficiency of the linear engineering, programs are used to optimize the time-consuming framing and layout operations. First, the drawing sheet format and scale are configured, and the length and width of the print area are defined. Then, the centerline is segmented and the drawing simplified according to the stake number with coordinates exported sequentially by chainage. The drawing can be segmented into sheets by using two layout methods: Fixed-size (constrained length and width) or Adaptive-length (width-constrained only). Seamless joint of adjacent sheets’ print areas is guaranteed. The alignment azimuth is determined by the start and the end stake points of each drawing sheet, while the geometric center is calculated based on the stake point set. The alignment azimuth and the geometric center are used to adjust the position of the print, making it vertically centered from left to right within the viewport in paper space. Compared to traditional methods, new method improves workflow efficiency by nearly two orders.
