Ocean Engineering最新文献

{"title":"Improved optimal torque control for large scale floating offshore wind turbines based on interval type-2 fuzzy logic system","authors":"Shenghua He ,&nbsp;Bing Wang ,&nbsp;Yuquan Chen","doi":"10.1016/j.oceaneng.2025.121186","DOIUrl":"10.1016/j.oceaneng.2025.121186","url":null,"abstract":"<div><div>As floating offshore wind turbines (FOWTs) evolve toward large capacities, the dynamic response lag caused by large rotor inertia become increasingly significant in the wind energy conversion system (WECS). This paper introduces a novel torque compensation method to enhance the traditional optimal torque control (OTC) response speed. In this improved OTC (IOTC) scheme, the impact of the floating platform pitch motion on aerodynamics is considered. The influence of the torque compensation on system responsiveness and stability is also analyzed. Based on this analysis, an interval type-2 fuzzy logic system (IT2-FLS) is designed to adapt the compensation coefficient adaptively. Multiple simulation experiments are performed on a 15 MW FOWT model to verify the effectiveness of the proposed method. The results show that the proposed approach surpasses traditional OTC and optimal tip speed ratio (TSR) methods in terms of power output. Additionally, introducing the IT2-FLS enhances power stability compared to fixed compensation coefficients and type-1 fuzzy logic systems (T1-FLS).</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121186"},"PeriodicalIF":4.6,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143854450","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards MASS: A concept and a framework for operating only once of electromechanical devices on ocean-going merchant vessels","authors":"Yuanyuan Tang ,&nbsp;Chenglei Yang ,&nbsp;Yu Xia ,&nbsp;Le Cao ,&nbsp;Jundong Zhang","doi":"10.1016/j.oceaneng.2025.121319","DOIUrl":"10.1016/j.oceaneng.2025.121319","url":null,"abstract":"<div><div>The rapid advancement of autonomous maneuvering technologies for ships stands in stark contrast to the sluggish progress in electromechanical devices operation. To address this gap and improve the intelligence of marine engine system, the concept of \"operating only once\" for electromechanical devices is proposed, and its implementation framework is presented. Whether performed onboard or from a remote shore center, operating marine engine room devices through individual sequential commands proves user-unfriendly. Such operation is mentally strenuous and inefficient. Moreover, when conducted from a shore center, it introduces safety hazards due to potential data transmission failures. The concept of operating only once consolidates a sequence of commands into a single friendly command, enabling marine engineers to focus on operational objectives rather than intricate procedural details. These underlying commands are generated based on graphs, path planning algorithms, and real-time measurement system. Considering the complexity of operational commands within the marine engine room, a layer graph approach is proposed and utilized. Each comprehensive graph is decomposed into multiple sub-layer graphs. The high, medium, and low commands are designed to enhance flexibility and efficiency. To validate our proposed concept, tasks of supplying power to emergency grid under normal condition and fault condition are tested. The performance of this automatic terminal is compared against three chief engineers and three trainees. Results show that in the case of normal condition, the automatic terminal completes the task in 48 s, whereas Chief engineers average 130 s and trainees average 402 s. In the case of 24V power failure, automatic terminal completes the task in 51 s, compared to average 145 s for chief engineers, and average 532 s for trainees. Feedback from both trainees and engineers confirms that the automatic terminal is highly user-friendly and intuitive. With further development of this concept and its real-world application onboard, autonomous ships will become an increasingly attainable reality.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121319"},"PeriodicalIF":4.6,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143854747","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental investigation on kinematic characteristics and slamming loads of a free-fall lifeboat model entering into water","authors":"Yang-Yue Yan,&nbsp;Zhi-Dong Wang,&nbsp;Hong-Jie Ling,&nbsp;Feng Xu,&nbsp;Peng Dou,&nbsp;Guo-Huai Sun","doi":"10.1016/j.oceaneng.2025.121260","DOIUrl":"10.1016/j.oceaneng.2025.121260","url":null,"abstract":"<div><div>The rapid immersion of free-fall lifeboats into water produces intense slamming forces, directly affecting the safety of onboard personnel. The study carried out a series of experimental drop tests using lifeboat models. A 4 × 4 array of pressure sensors was positioned on the lower surface of the lifeboat's bow, a gyroscope and an accelerometer were installed within the lifeboat. The research investigates the distribution law of slamming loads at the bow, and change law of attitude angle and acceleration during water entry. To explore the influence of initial slide parameters on water entry velocity and attitude, an adjustable sliding test device was designed, allowing for variations in slide angle, length, and drop height. Additionally, an image recognition system was developed to capture the motion trajectory, attitude, and velocity before water entry. A 0.78 % error margin was determined by comparing identified attitude angles with gyroscopic data, confirming the system's reliability and accuracy. The findings indicate that increasing the lifeboat's slide angle from 30° to 60° significantly reduces the peak slamming pressure, and the maximum slamming pressure coefficient <em>C</em>_<em>p</em> occurs at 0.24 <em>L</em>_<em>OA</em> in front of the center of gravity.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121260"},"PeriodicalIF":4.6,"publicationDate":"2025-04-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143852219","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical simulation of diameter-to-depth ratio on hydrodynamics in four tank structures","authors":"Chenxu Zhao ,&nbsp;Shupeng Du ,&nbsp;Wei Sun ,&nbsp;Yifan Wang ,&nbsp;Wei Zhao ,&nbsp;Chao Ma ,&nbsp;Zhen Ma ,&nbsp;Xiaozhong Ren","doi":"10.1016/j.oceaneng.2025.121262","DOIUrl":"10.1016/j.oceaneng.2025.121262","url":null,"abstract":"<div><div>The hydrodynamic performance of aquaculture tanks is crucial for fish welfare and tank self-cleaning. To optimize tank geometry and improve the flow environment, this study employed computational fluid dynamics to investigate the effects of varying diameter-to-depth ratios (<em>L/H</em>) on four tank types: circular, square arc angle, octagonal, and square. The hydrodynamic performance was assessed by analyzing flow velocity, vortex generation, turbulence kinetic energy, turbulence dissipation rate, and effective energy utilization. The numerical model was validated through physical experiments. Results indicated that increasing the diameter-to-depth ratio within the same tank type led to a progressive decrease in turbulence intensity, an expansion of low-velocity areas, and a reduction in average velocity and energy utilization coefficient. Optimal diameter-to-depth ratios ranged from 2:1 to 5:1 for circular, square arc angle, and octagonal tanks, and 2:1 to 3:1 for square tanks. Tanks within these optimal ranges exhibited superior hydrodynamic performance. Overall, this study provides a theoretical basis for selecting aquaculture tanks with optimal diameter-to-depth ratios.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121262"},"PeriodicalIF":4.6,"publicationDate":"2025-04-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850085","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrated damage detection and time-series data augmentation for floating offshore mooring systems via variational semi-supervised learning","authors":"Pranjal Tamuly ,&nbsp;Smriti Sharma ,&nbsp;Vincenzo Nava","doi":"10.1016/j.oceaneng.2025.121199","DOIUrl":"10.1016/j.oceaneng.2025.121199","url":null,"abstract":"<div><div>The dynamics and stability of the semi-submersible offshore platforms are significantly impacted by the degradation of the mooring system. Identifying structural integrity issues in mooring systems through a data-driven approach is challenging due to the infrequency of damage events and the difficulties in recording them. To address these challenges, this study proposes the Time-Series Variational Semi-Supervised Learning (TSVSSL) framework, which effectively bridges the gap between supervised and unsupervised learning by leveraging unlabelled data for damage detection. The proposed framework features a distinctive training procedure in which the encoder-decoder and classifier components are trained concurrently. This process produces a well-clustered latent representation that enhances damage detection and supports class-specific artificial data generation. A numerical study using simulated responses of a 5 MW semi-submersible FOWT under varying metocean conditions demonstrated that the proposed framework outperformed existing deep learning methods in damage detection, achieving superior accuracy, precision, recall, and F1 score. Further, a rejection sampling technique is also introduced to effectively generates artificial data that closely aligns with actual time series displacement response. The novelty of the proposed framework lies in its dual focus on damage detection and artificial data generation marking a significant advancement in the data-driven assessment of mooring systems.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121199"},"PeriodicalIF":4.6,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A theoretical model for clay subjected to episodic cyclic loading and reconsolidation","authors":"Qian Bi ,&nbsp;Youhu Zhang ,&nbsp;Yusuke Suzuki ,&nbsp;Nallathamby Sivasithamparam","doi":"10.1016/j.oceaneng.2025.121261","DOIUrl":"10.1016/j.oceaneng.2025.121261","url":null,"abstract":"<div><div>Offshore structures typically experience multiple storms during their service life. The soil around the foundations of offshore structures is subjected to cyclic loading during storm and reconsolidates between storms. Therefore, it is essential to understand the fundamental soil behaviour under episodic cyclic loading and reconsolidation to evaluate the long-term serviceability of offshore foundations. This paper presents experimental results of a comprehensive suite of cyclic DSS tests on a normally consolidated silty clay. The tests explore the soil response under different cyclic loading patterns (e.g., one-way or two-way), different cyclic amplitudes and number of cycles. A theoretical model, which combines the conventional cyclic contour diagram approach and principles of the critical state soil mechanics, is proposed and validated for predicting the cyclic soil response during undrained cyclic loading and hardening after reconsolidation. The model proposed in this paper paves a critical step for developing long-term soil-structure interaction models that are fundamentally linked to soil element level responses.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121261"},"PeriodicalIF":4.6,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143850083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Integrating DL-based surrogate within an Interacting Particle Ensemble Kalman Filtering framework for computationally efficient condition monitoring of FOWT moorings","authors":"Ananay Thakur ,&nbsp;Rohit Kumar ,&nbsp;O.A. Shereena ,&nbsp;Smriti Sharma ,&nbsp;Dongsheng Li ,&nbsp;Subhamoy Sen","doi":"10.1016/j.oceaneng.2025.121223","DOIUrl":"10.1016/j.oceaneng.2025.121223","url":null,"abstract":"<div><div>Traditional model-driven strategies for monitoring the condition of moorings in Floating Offshore Wind Turbines (FOWTs) depend on resource-intensive simulations of intricate high-fidelity models. Conversely, data-driven methods offer unbiased and prompt results but necessitate comprehensive labeled datasets that cover various damage scenarios, which are limited for FOWTs. Furthermore, the significant uncertainties associated with FOWTs’ operational environments complicate matters, making probabilistic estimation essential. To tackle this, filtering-based probabilistic methods are pertinent, although they typically require repetitive simulations of high-fidelity models.</div><div>An innovative solution involves replacing the high-fidelity model with a Deep Learning (DL)-based surrogate acting as a “data-based predictor” (DBP) to simulate FOWT dynamics. Utilizing a Fully Connected Neural Network (FCNN) architecture, the DBP is trained on synthetic time series data from a calibrated OpenFAST model, enabling it to learn FOWT dynamics and make one-step-ahead predictions based on current responses and health states, thus facilitating real-time monitoring. This surrogate model is integrated into a stochastic inverse estimation framework using the Interacting Particle Ensemble Kalman Filter (IPEnKF) to assess mooring health. Comprehensive tests on the NREL 5-MW wind turbine model mounted on an OC4 semi-submersible platform under varying noise levels, damage, and sea conditions demonstrate the method’s accuracy, precision, detection promptness, and reliability.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121223"},"PeriodicalIF":4.6,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848363","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Three-degree-of-freedom vortex-induced motions of an OC4 floating offshore wind turbine platform under different current incidences","authors":"Yuxin Yang,&nbsp;Yuanchuan Liu","doi":"10.1016/j.oceaneng.2025.121240","DOIUrl":"10.1016/j.oceaneng.2025.121240","url":null,"abstract":"<div><div>For column-type floating structures operating in current flow, significant oscillatory responses known as vortex-induced motions (VIM) can be excited, greatly impacting structure stability and safety of mooring lines. In this work, three-degree-of-freedom (DoF) VIM, including in-line, transverse and yaw motions, of a 1:72.72 scaled OC4 semi-submersible floating offshore wind turbine platform is investigated numerically across a wide flow velocity range, using a Computational Fluid Dynamics approach together with a Detached-Eddy Simulation model for turbulent flows. To analyze the impacts of current incidence on platform VIM responses, three representative current incidence angles of 0°, 60°, and 90° are examined. Results reveal that the “lock-in” phenomenon appears for the transverse motion within the reduced velocity (<em>V</em>_<em>r</em>) range of 8–12 at 0° and 90°, but the “lock-in” range narrows down to 8 ≤ <em>V</em>_<em>r</em> ≤ 10 at 60° incidence with smaller response amplitudes, suggesting that three-column platforms can be installed with two columns placed upstream to minimize VIM impacts. Meanwhile, comparing results between two models with and without the yaw motion demonstrates that the yaw DoF can induce significant in-line and transverse motions even at <em>V</em>_<em>r</em> ≥ 18 and thus must be taken into consideration in VIM simulations to accurately capture the platform motion characteristics at high flow velocity. Additionally, for the yaw motion <em>V</em>_<em>r</em> should be redefined with its natural period to yield a “lock-in” range similar to that of the transverse motion. Furthermore, connecting structures can apply substantial negative work upon the platform, demonstrating their important role in VIM suppression, and therefore should not be neglected in geometrical models. Additionally, the downstream column experiences significantly smaller mean drag due to the shielding effect exerted by the upstream column.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121240"},"PeriodicalIF":4.6,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848357","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Stability analysis on internal flow-induced cold-water pipe with non-uniform and variable cross-section for OTEC subject to multiple clump weights","authors":"Jian Tan ,&nbsp;Menglan Duan ,&nbsp;Chen An ,&nbsp;Renjie Yang ,&nbsp;Songlin Gao ,&nbsp;Yulong Zhang ,&nbsp;Segen F. Estefen","doi":"10.1016/j.oceaneng.2025.121191","DOIUrl":"10.1016/j.oceaneng.2025.121191","url":null,"abstract":"<div><div>The stability of variable cross-section cold-water pipes (CWPs) is crucial for ensuring the reliability and safety of Ocean Thermal Energy Conversion (OTEC) systems under complex marine conditions. This paper introduces a novel semi-analytical framework to assess the stability of CWPs subjected to multiple clump weights, which is ignored by previous works. The dynamic response equation is established based on the Euler-Bernoulli beam theory, accounting for both inertia forces and gravitational effects of the clump weights. To efficiently and accurately compute the dynamic stability of variable cross-section CWPs, a hybrid method integrating the Sturm-Liouville Eigenvalues Using Theta matrices (SLEUTH) with the Generalized Integral Transform Technique (GITT) is proposed. The problem is transformed into an auxiliary eigenvalue problem and a second-order differential equation with time-dependent coefficients. Eigenvalues and eigenfunctions are computed at discrete points using the SLEUTH method, while coefficients of the differential equation are determined through numerical techniques like the Newton-Cotes formula, Gaussian functions, and exponential functions. The GITT method is employed to solve the transverse vibration equation. Validation with numerical examples demonstrates rapid convergence and high accuracy. Further investigation reveals that the weight, position, and number of clump weights significantly influence CWP stability, providing key insights for OTEC design improvements.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121191"},"PeriodicalIF":4.6,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Energy-constrained collaborative path planning for heterogeneous amphibious unmanned surface vehicles in obstacle-cluttered environments","authors":"Shihong Yin,&nbsp;Zhengrong Xiang","doi":"10.1016/j.oceaneng.2025.121241","DOIUrl":"10.1016/j.oceaneng.2025.121241","url":null,"abstract":"<div><div>Amphibious unmanned surface vehicles (AUSVs) have gained attention due to their ability to operate across both water surfaces and aerial environments. However, path planning for multiple AUSVs in obstacle-cluttered environments, considering energy consumption, safety, and collaboration, remains a significant challenge. This paper addresses the collaborative path planning problem for multiple AUSVs, focusing on optimizing path length, threat avoidance, path smoothness, energy consumption, and collaboration efficiency in complex environments. A novel hyper-heuristic evolutionary algorithm combined with proximal policy optimization (HEA-PPO) is proposed. This approach utilizes reinforcement learning to dynamically select suitable evolutionary operators, reducing human intervention and enhancing search efficiency. An adaptive waypoint encoding strategy is also introduced to improve path smoothness in cluttered environments. Experimental results show that the HEA-PPO algorithm outperforms existing algorithms regarding path quality, convergence speed, and robustness. The proposed method optimizes safety, energy consumption, and collaboration time across multiple scenarios. The HEA-PPO algorithm significantly improves the robustness and efficiency of collaborative path planning for AUSVs, demonstrating its potential in complex, obstacle-cluttered environments. Integrating reinforcement learning with evolutionary algorithms provides a promising approach for future path-planning applications.</div></div>","PeriodicalId":19403,"journal":{"name":"Ocean Engineering","volume":"330 ","pages":"Article 121241"},"PeriodicalIF":4.6,"publicationDate":"2025-04-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143848361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}