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[Purpose] As critical operational equipment in marine scientific research, scientific winch systems perform essential functions in launching and recovering the underwater equipment for deep-sea resource exploration, geological sampling, and environmental monitoring. With the accelerated development of global marine resources and the continuous expansion of research vessel fleets, the performance demands on winch systems have increased, and market demand has shown a significant growth trend. [Method] Functions and application scenarios of different scientific research winch systems are reviewed, key technologies are summarized, and future development trends are explored. [Result] The application of key technologies such as lightweight design, multi-layer winding, cable arrangement, and wave compensation in the scientific research winch system can significantly improve the performance and operational capabilities of the winch. The scientific research winch system will develop towards heavy-duty, intelligent, and modular directions. [Conclusion] The research results can provide some references for the design optimization and related technical improvement of future scientific research winch systems.
[Purpose] In order to reduce the computational cost of numerical simulation for large-scale towing systems and improve the efficiency of numerical simulation, [Method] a method for unidirectional fluid-structure interaction is constructed by using the concentrated mass method and the Reynolds averaged equation. The effects of Reynolds number Re and Strouhal number St on scaling are discussed in detail, and the cable shape scaling ratio and cable diameter scaling ratio are applied to the analysis of scaling effects.[Result] The results indicate that Re plays an important role in the scaling process, while St shows a relative importance for transient effects. [Conclusion] The research results can provide some references for the scaled numerical simulation of large towing systems.
[Purpose] In order to reduce the operation and maintenance costs and downtime losses of offshore wind power, and improve the economic benefits, [Method] A comprehensive optimization algorithm for offshore wind power operation and maintenance planning that considers both economy and comfort is proposed. By establishing an optimization model and a fast forecasting method, combined with a genetic algorithm for solving, the optimal operation and maintenance plan is determined. [Results] A case study is conducted on a floating wind farm with 80 floating wind turbines(5 MW) and an installed capacity of 400 MW. The results show that the total operation and maintenance cost of the wind turbines can be reduced by about 47.7%. [Conclusion] The research results can provide some references for cost reduction and efficiency improvement in operation and maintenance of offshore wind power.
[Purpose] In order to improve the ability of wind turbines to obtain wind energy and stable output power, [Method] a mathematical model of a 10 MW medium-speed permanent magnet semi-direct drive offshore wind turbine is established. Based on the improved active-disturbance rejection controller,Arnold mapping strategy, sine cosine function dynamic adjustment strategy, and logical chaos Cauchy mutation disturbance strategy are introduced to optimize the multi-strategy improved sparrow search algorithm(MISSA) and obtain a new type of pitch controller. [Result] The results indicate that the optimized pitch control system based on the improved active anti-interference controller significantly improves the anti-interference performance and output power stability of the wind power system.[Conclusion] The research results can provide some references for the design of variable pitch system controllers.
[Purpose] To explore the distribution of excitation sources for ship vibration noise and its impact on various navigation processes of ships, [Method] the current research status of ship vibration and noise reduction at home and abroad is summarized, mainly focusing on the distribution characteristics of excitation sources for ship vibration noise and the current status of ship noise reduction technology.Suggestions are made on the problems faced by China's current ship vibration reduction materials and vibration control technology, and prospects for future development trends are discussed. [Result] The research shows that the comprehensive application of new materials and vibration control technology in ships can provide more optimal design concepts for modern ships, significantly improve the operational performance and safety of ships, and help establish a sound standard system for ship vibration reduction technology. [Conclusion] The research results can provide some references for the excitation source and control technology of ship structural vibration.
[Purpose] In order to select appropriate parameters for the disc separator drum and improve the separation performance and efficiency of the separator, [Method] CFX software is used to numerically simulate the internal flow field of the separator drum; the influence characteristics of the drum operating speed, the cone angle of the disc bus and the large end radius of the discs on the separation performance are analyzed using the single variable method and the interpolation method. [Result] The results indicate that increasing the rotational speed and the number of discs will increase the processing capacity of the separator and improve the volume fraction of oil at the outlet of the oil phase; the separation performance will decrease if the cone angle of the busbar is too large or too small, and there is an optimal value of 45°;the large radius of the disc is positively correlated with the processing capacity of the separator, but the growth rate shows a tendency of first increasing and then decreasing. [Conclusion] The research results can provide some references for the selection of drum parameters for disc separators.
[Purpose] To quantify the abnormal propagation behavior of small cracks and predict the initiation life of fatigue cracks, [Method] the interaction between different mechanical parameters such as stress gradient and stress intensity factor range during the process of small crack propagation is analyzed in depth, and a new mechanism for small crack propagation is proposed based on this. [Result] The results indicate that the stress gradient generated by small crack propagation can explain the difference between the sharp notch fatigue stress concentration factor K_f and the static stress concentration factor K_t. The predicted fatigue crack initiation life of the model is in good agreement with the experimental data. The new mechanism can not only effectively quantify the abnormal propagation behavior of small cracks, but also accurately predict the initiation life of fatigue cracks. [Conclusion] The research results can provide some references for predicting the fatigue life of small cracks at the root of narrow gap structures.
[Purpose] In order to reduce the complexity and inference time of the Transformer model and improve the accuracy of extremely short-term ship motion prediction, [Method] the traditional LSTM model and the improved LSTM-OneShot model are used for pre-training. The gradient boosting decision tree(GBDT) algorithm and the ensemble learning approach are borrowed, and attention mechanism is introduced based on the Transformer model to correct prediction residuals. The experiment is conducted using the time history data of a certain ocean going vessel under class Ⅲ sea conditions. [Results] The research shows that: 1) Transformer correction can significantly improve the prediction accuracy of LSTM models in predicting ship motion curves. When the forecast duration is 2 s, the goodness of fit coefficient R~2 can be increased from 0.807 to 0.940; Transformer correction can improve the prediction accuracy of the LSTM-One Shot model to a certain extent. For a prediction period of 2 s, R~2 can be increased from 0.938 to 0.941; the LSTM-One Shot model modified by Transformer performs the best overall. 2) In terms of predicting the envelope of the ship motion, the periodicity of the envelope is not significant in the feasible input sequence time, and the historical features extracted by the multi-layer perceptron become interference information, resulting in significantly worse prediction results of the LSTM One Shot model compared to traditional LSTM models. At a prediction duration of 2 s, R~2 decreased from 0.938 to 0.881; modifying the attention mechanism can significantly improve the prediction accuracy of traditional LSTM models. At a prediction duration of 2 s, R~2 increased from 0.938 to 0.963; Attention mechanism modification can improve the prediction accuracy of the LSTM One Shot model to a certain extent, but it cannot fundamentally remove the interference information brought by multi layer perceptrons. At a prediction duration of 2 s, R~2 can increase from 0.881 to 0.887; The traditional LSTM model modified by Transformer performs the best overall. [Conclusion] The research results can provide some references for extremely short-term forecasting of ship motion.
[Purpose] To study the scheduling problem in ship cutting production workshops, an improved non-dominated sorting algorithm is proposed with the objectives of minimizing the maximum completion time and minimizing the load balancing value of each process equipment. [Method] The specific improvement of the algorithm includes adopting two-stage encoding and separately designing transcoding methods to achieve the mapping between the continuous search space of the walrus algorithm and the discrete decision space of the workshop scheduling; integrating the discrete crossover mutation strategy of the genetic algorithm to enhance the communication between the Walrus populations, avoid the algorithm getting stuck in local optima, and improve the algorithm's global and local search capabilities; two types of local searches have been introduced for load balancing of equipment in various processes, effectively expanding the search area of the solution space and further enhancing the algorithm's local optimization capability; introduce non dominated sorting and crowding degree calculation to achieve the solution of multiple objectives. Research on a cutting production workshop example of a certain shipping company,and compare the solution results of the improved non dominated sorting algorithm with other algorithms. [Result] The results indicate that the algorithm is effective. [Conclusion] The research results can provide some references for the scheduling optimization of multi-objective ship cutting production workshops.