Data preprocessing is a core step in knowledge graph construction, consisting of two main stages: data collection and information extraction. This paper systematically reviews mainstream data preprocessing methods based on rules and lexicons, statistical machine learning, and deep learning, and thoroughly analyzes their technical principles and application limitations in entity recognition and relation extraction. Existing methods rely heavily on manual rules and suffer from weak semantic generalization, making it difficult to achieve cross-domain knowledge transfer. To address these issues, this paper explores a novel paradigm of “semantic-driven and automated extraction” based on large language models. By generating deep semantic embeddings through pre-trained large language models and combining vector similarity computation, it enables unsupervised and context-aware information extraction, driving the intelligent transformation of knowledge graph construction. The current approach is still in the exploratory stage, facing challenges such as high computational cost and low interpretability. Future research should focus on lightweight model design, multimodal semantic alignment, and domain knowledge integration to improve the efficiency of knowledge graph construction and model interpretability.

The gasification process is the core of the marine fuel gas supply system, whose simulation research is critical for ensuring the rational design of the gasification system and the safe operation of the fuel gas supply system.The optimization of gasification scheme was carried out based on the high- and low-pressure fuel gas supply system of a large LNG-powered vessel. A method for simulating the gasification process using Aspen HYSYS software under the maximum operating condition was proposed, to verify the rationality of the gasification scheme. And, the gasification process under various typical operating conditions was then simulated and validated. The influence of LNG methane concentration and inlet pressure on the design of the gasification scheme was explored. It was found that the heat duty of the vaporizer increased with LNG methane concentration and decreased with inlet pressure. This provides a theoretical basis for the optimal design of the gasification process in marine fuel gas supply systems and contributes to the safe and stable operation of dual-fuel power systems.

Water-lubricated bearings are critical components in marine propulsion systems, directly influencing vessel operational safety and reliability. This study investigates the mechanism of water film pressure distribution under different slat profiles by establishing a fluid-structure interaction (FSI) analysis model of the bearing. Systematic numerical calculations were carried out for various slat types and groove arrangements. The effects of flat, convex, and concave slats on bearing load capacity and wedge-shaped water film pressure distribution were compared. The results indicate that concave slats generate a larger positive pressure zone in the circumferential direction and exhibit more continuous water film pressure distribution. In the studied 24-slat bearing, the difference in maximum water film pressure between the slat-down and groove-down arrangements was only 1%. In contrast, the local groove configuration increased maximum water film pressure by 17.6% compared to the other two arrangements, also demonstrating superior axial pressure distribution. In conclusion, the combination of concave slats and a local groove design significantly enhances the load-carrying capacity and operational reliability of large-scale water-lubricated bearings.

This study investigates the slamming load characteristics on the ladder of the self-propelled cutter suction dredger Tianjing under head-sea conditions. The vessel’s motion responses are computed based on potential flow theory, and the slamming pressures on the ladder are analyzed using the Von Kármán and Wagner impact theories, as well as the GJB design code method. Results show that the GJB method is more suitable for evaluating hull slamming loads. Ladder slamming predominantly occurs near the waterline, and the impact loads follow a three-parameter Weibull distribution. Increase in ship size significantly reduces motion responses, slamming frequency, and pressure intensity. However, short-period waves tend to intensify slamming risks. Based on the three-parameter Weibull model and extreme value theory, the design extreme values of ladder slamming pressure are predicted, providing a reference for the structural design of next-generation large self-propelled cutter suction dredgers.

To improve the efficiency and accuracy of 3D hull modeling, address data fragmentation issues when exporting hull models from different software, reduce the data volume of hull surfaces, and better support hydrodynamic performance calculations and experimental model fabrication, this paper proposes a hull modeling method based on offset points and lines plan using CATIA V6. A technical system is established for repairing defective hull models, reconstructing surfaces, and verifying quality. A series of EKL programs are developed for rapid hull modeling. CATIA V6 offers powerful logical and professional capabilities, making it well suited for modeling marine engineering series models. The development and summarization of hull modeling methods based on CATIA V6 are of positive significance for the overall design of ships.

Additional resistance induced by shallow water effects is a critical factor influencing fuel economy during ship design and operation, especially in shallow sea areas such as the Baltic Sea. To address fuel efficiency challenges in such regions, this paper proposes a speed optimization model that accounts for shallow water resistance. The model adopts a multi-objective genetic algorithm integrated with a hypervolume indicator to optimize both total fuel consumption and voyage time. Three operational strategies are investigated: minimizing overall fuel consumption, applying shallow water resistance constraints, and maintaining constant optimal engine power. The effectiveness of each strategy is assessed on a typical Baltic route. Results show that the proposed optimization strategy can reduce fuel consumption by approximately 3.6% without compromising voyage schedules. Moreover, the additional fuel consumption attributed to shallow water effects can be limited to 2.5%. The proposed approach demonstrates strong effectiveness and engineering applicability, providing theoretical support and optimization guidance for green ship design and intelligent speed control.

Ice-induced vibration is a significant risk factor for the operational safety and structural stability of offshore oil platforms. If the hazards posed by sea ice, currents, and other environmental loads are not properly assessed, offshore platforms may suffer catastrophic consequences such as collapse, oil spills, and casualties. Due to the uncertainty of ice load and ice-induced vibration, traditional numerical analysis and statistical prediction methods struggle to simultaneously meet the requirements for high-precision early warning and timeliness in ice-induced vibration risk assessment. Therefore, based on the measured winter sea environment data of the JZ20-2MUQ platform in the Bohai Sea, this paper uses the interpretive structural model (ISM) and the expectation maximization (EM) algorithm to construct a Bayesian network model. Quantitative analysis indicates that the main risk factors affecting the vibration of the offshore oil platform in the Bayesian network are ice thickness, ice velocity, ice direction, wind speed, and tidal flow velocity and direction. Furthermore, the accuracy and validity of the model are verified. The average accuracy of the model is over 0.75, and the accuracy of the target node is above 0.9. Verification results confirm that the model has high accuracy and can provide reliable data support for risk prediction.

When navigating in coastal areas, a ship may collide with a coastal bank, resulting in grounding. This issue involves interactions among the wave, the ship, and the coastal bank, with the key aspect being the contact between the ship and the bank. To solve this problem, a smoothed particle hydrodynamics (SPH) method is employed to simulate wave motion, wave-ship interaction, and wave-bank interaction. A discrete element method (DEM) is used to handle the interaction between the ship and the bank. Accordingly, a coupled SPH-DEM approach is established to study ship grounding. Numerical analysis is conducted for a bank with a 1:10 gentle slope under three wave periods, focusing on ship motion responses of pitch, surge, heave, and contact forces between the ship and the bank. The results show that under short-wave-period conditions, the ship remains grounded on the bank with small motion responses. Under the long-wave-period condition, the ship lifts off the bank and floats freely, with significantly increased motion responses. Regarding the contact forces between the ship and the bank, the vertical components are significantly larger than the horizontal components. In the early stage of grounding, the vertical components of the contact forces reach their peak values, accounting for up to 65.52% of the ship's gravity for all test cases. In the stable stage, the vertical components account for 32.84% and 41.89% of the ship's gravity for the two short-wave-period cases, and decrease to 0% for the long-wave-period case as the vessel is no longer grounded.

The cargo containment system of a liquid hydrogen carrier operates at extremely low temperatures, and the hull structures are also exposed to such low temperatures, resulting in a significant temperature gradient. This temperature gradient poses a threat to the safety of both the cargo containment system and the hull structure. This study conducts a temperature field analysis of the hull structure and cargo containment system of a 40 000 m³ liquid hydrogen carrier. The computational fluid dynamics (CFD) method is adopted, considering thermal conduction, thermal convection, and thermal radiation, as well as the thermal coupling effect of the hull structure. A partial cargo hold model is adopted for analysis, which properly reflects the structural arrangement of the cargo hold area and the cargo containment system. The temperature distribution in the cargo holds is analyzed based on the IGC (International Code for the Construction and Equipment of Ships Carrying Liquefied Gases in Bulk) and USCG (United States Coast Guard) load cases. The results provide a reference for the design of similar vessels.

To determine whether the hydrogen release rate of a solid-state hydrogen storage tank can meet the power response requirements of a hydrogen-powered inland river vessel, a simulation analysis was conducted to study its operational characteristics. A 3 000-ton inland container ship was selected as the research object. A whole-ship multi-system integrated power simulation model and a solid-state hydrogen tank model were developed in MATLAB/Simulink. Two calculation conditions were designed: calculating the minimum lithium battery capacity configuration and analyzing the dynamic characteristics of the solid-state hydrogen tank. The results show that, while satisfying the target speed (with a mean squared error of less than 5% between feedback and target speeds), the calculation of minimum lithium battery capacity must account for both the depth of discharge and the limitation imposed by the maximum charging current on the rated capacity. When the lithium battery is configured to minimum capacity, the hydrogen storage mass fraction, temperature, and pressure of the solid-state hydrogen tank remain within the design limits throughout the entire voyage. Additionally, the heat output of the fuel cell meets the thermal demand during hydrogen release from the solid-state hydrogen tank. These results indicate that the hydrogen release rate of the solid-state hydrogen tank can satisfy the propulsion power response requirements of the target vessel. Finally, suggestions for practical application are provided: under low-load conditions, the temperature and flow rate of the circulating heating water for the solid-state hydrogen tank must be dynamically adjusted according to hydrogen consumption demand; otherwise, the tank pressure and temperature may exceed allowable limits. To avoid a sharp pressure drop during the initial hydrogen release stage, a buffer tank should be configured and operated in conjunction with the solid-state hydrogen tank in practical applications.

Since the beginning of the 21st century, with the rapid development of the new-generation information technology and high-end manufacturing industries, major shipping and shipbuilding nations have engaged in research and demonstration projects on intelligent ships, and have accelerated their strategic positioning in this field in recent years. This paper analyzes the water environment and navigation characteristics of inland waterways, reviews research progress on key technologies for intelligent inland ships—including intelligent navigation, cybersecurity, intelligent devices and systems, testing, verification, and evaluation—as well as the development of classification standards for intelligence levels of inland ships. It also presents typical engineering cases of intelligent inland ships and discusses future development trends. At present, the overall development of intelligent ships is still in its early stages. The domestic shipbuilding and shipping industry should align with China's development strategy of “new quality productive forces” to strengthen the domestic industrial chain and consolidate the industry's leading position in the new economic development paradigm.

Alternative design and arrangements (AD & A) represent both a distinctive feature and a challenge in cruise ship design, and constitute one of the core technologies that must be urgently mastered to achieve independent design of cruise ships in China. Four typical application scenarios of AD & A for cruise ship fire safety, namely super-large main vertical zones, lifts without independent machine rooms, non-steel structural materials, and super-large fire doors, are first analyzed. The process of AD & A for fire safety is then summarized and refined, providing a concise overview of the main tasks involved in the four stages: preparation, preliminary qualitative analysis, quantitative analysis, and final scheme implementation. Finally, the key technologies and research progress in AD & A for cruise ship fire safety are elaborated in detail from three aspects: fire hazard identification, life safety performance criteria, and rapid approval of AD & A schemes. Meanwhile, several suggestions on the foundational works related to AD & A are offered.

Large cruise ships, as integrated energy systems combining propulsion and hotel services, are characterized by complex load structures, diverse operating conditions, and stringent emission constraints. With increasingly stringent decarbonization policies in international shipping and the transition of China’s cruise industry from import-based operation to independent design and construction, the issues of cruise operational optimization and energy management have evolved from standalone energy-saving measures into complex engineering problems involving multi-energy system coordination and full life-cycle optimization. This paper systematically reviews research on cruise operational optimization and energy management, summarizes the architecture and load characteristics of cruise energy systems, analyzes the current status of optimization methods and energy management strategies, and further discusses development trends such as multi-energy integration, low-carbon fuels, and data-driven approaches. The study provides a reference for improving energy efficiency, reducing carbon emissions, and promoting green maritime transport.

To improve the noise reduction accuracy of reciprocating friction vibration signals of piston ring friction pairs in marine diesel engines, this paper proposes a collaborative noise reduction method that integrates complementary ensemble empirical mode decomposition (CEEMD) and an adaptive correlation coefficient screening mechanism. Simulated vibration signals were obtained using the BRUKER UMT friction and wear testing machine to construct an experimental dataset. The original signals were subjected to multi-scale decomposition using CEEMD, and effective intrinsic modal components were screened using an adaptive correlation coefficient threshold. The dominant noise component was removed to achieve signal reconstruction. MATLAB software was applied to implement the noise reduction processing. Three types of indicators—signal-to-noise ratio (SNR), normalized cross-correlation coefficient (NCC), and mean square error (MSE)—were used for quantitative evaluation. Multi-scale permutation entropy (MPE) theory was also innovatively introduced to verify the dynamic characteristics of the denoised signal. The experimental results show that the CEEMD adaptive correlation coefficient screening method has significantly improved noise reduction performance compared to other methods. The correlation coefficients between the multi-scale permutation entropy image of the stripped noise signal and the overall laboratory noise signal image are all above 0.8, thus proving the accuracy of effective signal denoising.

Economic globalization has driven the development of China’s manufacturing industry. The rise of major clean energy projects such as offshore wind power has increased the demand for maritime transportation of super-large structures. In view of the problems of poor universality, cumbersome procedures, and high cost faced by the current lashing tools for super-heavy marine modules such as offshore wind power jackets during sea transport, this paper designs a new gantry-type lashing tooling and systematically evaluates its strength and deformation through finite element analysis. The results show that when transporting a typical wind power jacket module, the maximum stress and deformation of the tooling are 236.62 MPa and 2.15 mm, respectively; when transporting an offshore pile module, the values are 110.85 MPa and 1.80 mm, respectively. Both are below the allowable stress of Q355B steel (273.08 MPa). The tooling has reliable strength, strong versatility, and high reusability. It can significantly shorten the lashing preparation cycle for major components such as wind power jackets, reduce the comprehensive transportation cost, and provide a feasible solution for cost reduction and efficiency improvement in the maritime transport of major components within the offshore wind power industry chain.

The unsteady forces generated when a pump-jet propulsor operates behind a submarine hull are a major excitation source for hull vibration and radiated noise. Accurate prediction of these forces is therefore central to the design of low-noise propulsors. This study presents a numerical framework that couples the prediction of tonal forces via unsteady Reynolds-averaged Navier-Stokes (URANS) equations with the estimation of broadband forces using large eddy simulation (LES). The framework is applied to a model-scale pump-jet installed behind the SUBOFF hull. Numerical simulations characterize the unsteady forces on the rotor and stator blades, yielding their respective tonal and broadband force spectra. The results indicate that the tonal force and moment fluctuations occur predominantly at the first and the second blade passing frequency (BPF), while the broadband force and moment spectra exhibit a distinct hump around the first BPF.

To investigate the distribution and characteristics of slamming loads on a self-propelled jack-up wind turbine installation vessel (WTIV) during transit and preloading conditions, a three-dimensional hydrodynamic numerical tank model was established based on Computational Fluid Dynamics (CFD). The generation mechanism, time-history curves, and spatial distribution of slamming loads under operational sea states and two typical air gap conditions were obtained and analyzed. The results show that under transit (free-sailing) conditions, the peak slamming load increases with wave height and wave steepness, primarily depending on the water-entry velocity at the slamming point and the vessel's hull flare. During preloading operations, a trapped air cushion beneath the hull is significantly compressed and struggles to escape, leading to higher slamming loads at smaller air gaps. In the same region, slamming loads under beam seas are 6% to 14% higher than those under head seas, while also inducing a lateral horizontal load of approximately 300 t. The characteristics of slamming pressure obtained in this study provide critical references for the structural safety of similar vessels and safe operations during preloading conditions.

Self-propelled cutter suction dredgers feature large open slots at the bow and stern for equipment installation, giving them a hull form that is distinctly different from conventional merchant ships. Current loads constitute a major environmental force during their operation. This paper investigates the current load characteristics resulting from these large slots via computational fluid dynamics (CFD) simulations. Two typical hull configurations—the positioning-bow type and the excavation bow type—are examined. Simulations are performed on a scaled model using the SST k-ω turbulence model to analyze the variation in current loads under flow incidence angles ranging from 0° to 180°. The results show that the large open slots create pronounced low velocity zones and vortices behind the hull, significantly increasing the current load coefficients. For instance, at a 180° flow angle, the longitudinal current load coefficient of the excavation-bow type is 122% higher than that of the positioning-bow type. The transverse current load coefficient peaks at a 90° flow angle, exceeding the values given in the OCIMF charts by 18% and 13% for the two hull types, respectively. This study reveals the relationship between hull configuration and flow field characteristics, providing theoretical support for the design of large self-propelled cutter suction dredgers.

To meet the lightweight design requirements of ship composite structures, this paper proposes a multi-objective optimization method for composite laminate layup. The method integrates the NSGA-II algorithm with the micromechanical Voigt-Reuss model and classical lamination theory. Furthermore, a novel tiered constraint strategy, tailored to the loading characteristics of ship structures, is introduced for the first time in the industry, successfully achieving the multi-objective (dual-objective) optimization of laminate layups. Taking a 40-layer carbon-fiber laminate as an example, the optimized design achieves a 14.6% increase in stiffness and a 98% satisfaction rate of manufacturing constraints compared to conventional methods. Finite-element verification under clamped boundary conditions shows a 32% reduction in maximum stress and a 12% increase in the first-order natural frequency. The application of this method to a high-speed composite catamaran demonstrates that the optimized hull-girder design leads to a 10% reduction in deflection and a 15.6% decrease in the fiber stress utilization factor in longitudinal strength calculations. This study provides a valuable reference for advancing ply-optimization design techniques for ship composite structures.

Ship operational data are crucial for assessing vessel performance, predicting energy efficiency, and enabling predictive maintenance, thereby facilitating safe, efficient, and intelligent operations in the maritime industry. However, the effective utilization of such data is often hindered by poor data quality, high uncertainty, and complex processing workflows. To address these challenges, this paper proposes a robust framework for analyzing ship operational data. The framework enhances data usability by optimizing the procedures for data processing and analysis. Specifically, it incorporates a practical method for identifying steady-state operating conditions, establishes rational data filtering strategies, and applies internationally standardized methods for correcting environmental influences. The proposed framework is validated using real operational data from a container ship. Results demonstrate that the processed data can clearly reveal the vessel's long-term performance trends, providing a reliable basis for predictive maintenance decisions. This study offers a practical and effective solution for improving the quality and usability of ship operational data, thereby supporting the advancement of big-data applications towards smart shipping.

This paper investigates the multi-agent formation control problem for underactuated unmanned surface vehicles (USVs) and proposes a distributed control strategy based on partial differential equations (PDE), integrated with an improved artificial potential field (APF) method for obstacle avoidance. A leader-follower formation framework is first established, where the desired positions and tracking velocities of follower vessels are derived. Subsequently, a PDE-based formation control law is designed to ensure stability in multi-USV cooperative motion. The APF approach is enhanced by introducing tangential force components and angle-adaptive coefficients to optimize obstacle avoidance trajectories. The proposed algorithm is validated through simulations using ArduPilot-SITL, ROS, and QGroundControl, demonstrating its effectiveness in formation maintenance, formation switching, and obstacle avoidance. Experimental results show that the method achieves rapid convergence of formation errors while effectively avoiding static obstacles, exhibiting strong robustness and practical applicability.

To address the challenges of path planning for unmanned surface vessels (USVs) in complex environments and the relatively low efficiency of existing algorithms, this paper proposes a novel path planning method that integrates the artificial potential field (APF) approach with the rapidly-exploring random tree star (RRT*) algorithm—referred to as the bidirectional APF-RRT algorithm. The proposed method first introduces a goal-biased strategy, guiding newly generated nodes to expand preferentially toward the target direction. Additionally, a bidirectional search mechanism is adopted to drive two random trees toward each other, thereby accelerating the convergence speed of the algorithm. During node expansion, the attractive force from the artificial potential field guides the expansion toward the target, while the repulsive force enables effective obstacle avoidance. Finally, simulation experiments are conducted on the MATLAB platform to compare the proposed algorithm with traditional RRT* and APF-RRT* algorithms. Experimental results demonstrate that the bidirectional APF-RRT* algorithm outperforms the others in terms of the number of path nodes, path length, and planning efficiency across multiple typical scenarios, indicating superior planning performance and environmental adaptability.

During the 14th Five-Year Plan period, driven by multiple positive factors including a restart of the market cycle and a recovery in external demand, the global offshore engineering equipment market steadily recovered. As international energy prices bottomed out and rebounded, the product structure shifted significantly: floating production equipment became the market focus, offshore wind power orders emerged as a new growth driver, and prices for offshore support vessels continue to rise under capacity constraints. Looking ahead to the 15th Five-Year Plan period, fossil energy is expected to regain prominence as the global energy landscape undergoes profound adjustments. Non-market factors, such as great-power competition and geopolitics, alongside supply-demand fundamentals, will continue to influence energy prices. Consequently, demand for offshore oil and gas equipment orders remains robust, while long-term potential in offshore wind power, other marine renewables, and innovative marine structures continues to hold promise. This paper reviews the recovery and evolution of the global offshore market during the 14th Five-Year Plan period, analyzes the underlying shifts in supply and demand dynamics, and discusses the sector’s development path for the 15th Five-Year Plan period in the context of the ongoing global energy transition, to provide insights for the industry’s high-quality development.

In 2025, the global new shipbuilding market maintained its recent positive momentum, characterized by full orderbooks and sustained high prices, successfully concluding the 14th Five-Year Plan period (2021-2025). China's shipbuilding industry continued to lead global growth, with all major indicators reaching historic highs and further consolidating its position as the world leader. Looking ahead to 2026, operating at a market peak demands heightened caution. Potential risks such as geopolitical competition, demand adjustments, and financial volatility require vigilant attention. Crucially, it is essential to analyze whether the underlying supportive factors will fade, shift, or strengthen—especially regarding the sustainability of shipping demand, the scale of vessel scrapping, and the absorption of new tonnage capacity. These issues represent the core uncertainties and primary sources of divergence in market trend judgments. This paper reviews the development of the global new shipbuilding market in 2025, analyzes the key variables that will influence the market in 2026, forecasts future trends, and provides insights to the industry for its stable development.

To accurately evaluate the energy-saving performance of a pre-swirl duct (PSD) and reveal its underlying mechanisms, this study takes an 8,800 TEU container ship as the research subject. Numerical simulations of ship model resistance, propeller open-water performance, and self-propulsion performance were performed using the Reynolds-averaged Navier-Stokes (RANS) method. The numerical method was validated against towing tank test results. Based on this, the primary energy-saving mechanisms were systematically revealed by analyzing the effects of the PSD on the wake field, propeller performance, and wake kinetic energy. At the design speed, the predicted energy-saving rates are 2.78% (CFD) and 2.74% (EFD). Under off-design conditions, the average rates are 2.86% (CFD) and 2.72% (EFD), showing good agreement between predictions and experiments. The PSD generates a pre-swirl flow via its guide fins, which optimizes the propeller inflow, improves blade performance, and suppresses transverse flow in the wake. The accurate numerical method and the systematic analysis of energy-saving mechanisms presented in this study provide a foundation for future optimization of PSDs.

In the current era of major maritime strategies, the development of grand ocean science programs is becoming an important pathway for the advancement of ocean science. The international community has accumulated considerable experience in implementing such programs, but they face challenges such as insufficient support from high-tech equipment, inadequate research funding, and slow progress in international cooperation. Supported by policies for building a strong maritime country and advancing deep-sea science and technology, China has made certain progress in ocean science research. However, in the future, it will face challenges arising from extreme environments, integrated long-term three-dimensional scientific expeditions, and system integration. Therefore, it is essential to focus on the "four poles" of scientific research—extreme macroscopic, extreme microscopic, extreme environments, and extreme interdisciplinary integration—develop novel ocean technologies and domains, strengthen independent innovation and high-level international cooperation, and use high-tech research equipment as a driver to support future large-scale science programs in key areas.

To investigate the internal sound field of an enclosed cabin equipped with intake and exhaust ducts, numerical acoustic simulations were conducted using the acoustic module of the finite element software LMS Virtual Lab. The study focused on acoustic performance indicators such as the insertion loss of the intake and exhaust mufflers and examined the influence of the intake muffler on the cabin's sound field. The simulation results indicate that the pressure losses of the intake and exhaust mufflers are 19 kPa and 72 kPa, respectively, both meeting the design requirements. Within the frequency range of 20 Hz to 20 kHz, the insertion loss of both mufflers generally complies with the standard, though certain frequency bands still require further optimization. Specifically, the overall noise reduction effect of the intake muffler is slightly lower than that of the exhaust muffler, while the exhaust muffler’s noise attenuation performance in the high-frequency band needs improvement. From the cabin perspective, installing mufflers in the intake duct effectively reduces mid- and high-frequency noise inside the cabin. Additionally, accumulated water in the cabin smooths the sound spectrum and reduces noise, with this effect gradually stabilizing as water depth increases. This study provides valuable insights for optimizing the acoustic design of ship cabins.

To investigate the advantages of the toroidal propeller in hydrodynamic performance and the characteristics of its blade surface pressure distribution, this study first examined the configuration parameters of the toroidal propeller. A parametric modeling approach was applied to the entire propeller, leading to the development of a first-generation toroidal propeller model. Subsequently, based on the STAR-CCM+ software, the open-water performance and pressure distribution of the propeller were computed using the Detached Eddy Simulation (DES) turbulence model. A second-generation toroidal propeller was then developed by adjusting the pitch distribution, which optimized the surface pressure distribution. The research indicates that the configuration design of the toroidal propeller requires the introduction of new parameters. The open-water performance of the toroidal propeller follows a trend similar to that of conventional propellers, but its maximum efficiency is not ideal. The total thrust of the toroidal propeller is considerable; however, the selection of the airfoil and parameters may be unreasonable, leading to pressure loss in both the pressure and suction sides of the front blade and consequently degrading the surface pressure distribution to some extent. Adjusting the pitch distributions of the front and rear blades of the toroidal propeller can significantly optimize the pressure distribution on the blade surface.

Subsea pipelines are prone to developing cracks during long-term service, and traditional methods often suffer from low localization accuracy and poor stability in complex noisy environments. This study investigates defect localization based on an improved cross-correlation time delay estimation method for acoustic emission (AE) signals, which is significant for identifying and localizing sudden AE events under challenging conditions. AE detection technology, as a dynamic, real-time, and non-destructive evaluation method, captures transient elastic waves generated by internal structural changes due to stress or environmental variations, enabling early warning of potential damage and accurate health monitoring of structures. Experimental results demonstrate that the improved cross-correlation time delay method effectively enhances the localization accuracy for AE sources, achieving an average localization error of 0.0133 m and a relative error of 2.67%, which sufficiently meets practical requirements. The findings indicate that this method possesses high practical value for damage detection and localization analysis in complex structures.

As a lift-based energy-saving device, sails are increasingly deployed on modern ships to reduce fuel consumption and carbon dioxide emissions. This study investigates the performance of a NACA airfoil sail installed on a bulk carrier and identifies suitable areas for sail placement. Computational Fluid Dynamics (CFD) simulations were employed to analyze the flow fields around both the sail and the ship. The simulation results show good agreement with Experimental Fluid Dynamics (EFD) data. A comparison between the onboard sail and a freestanding sail reveals that the hull-induced airflow disturbance alters the lift characteristics of the sail. Furthermore, by analyzing the wind speed distribution above the deck under different wind directions, areas with higher wind speeds were identified, determining a "high-performance zone" more suitable for sail layout. This study provides valuable guidance for developing sail arrangement strategies in practical engineering applications.