Applied Ocean Research最新文献

{"title":"Fast real-time prediction of wave exciting force for a point absorber based on impulse response functions","authors":"Ryo Yoshimura,&nbsp;Takahito Iida,&nbsp;Md Shahidullah Kaiser,&nbsp;Kazuki Irifune","doi":"10.1016/j.apor.2025.104539","DOIUrl":"10.1016/j.apor.2025.104539","url":null,"abstract":"<div><div>Fast real-time prediction of wave exciting forces is necessary for the optimal control of Point Absorbers (PAs) in wave energy conversion. However, the non-causality of the impulse response function (IRF) of wave exciting force is a crucial issue for the prediction. To address this problem, this study employs deterministic wave prediction using upstream measured wave data. By integrating the IRFs of water waves and wave exciting forces, a real-time prediction method of wave exciting force is developed. Once the wave exciting force can be estimated, body motion, outgoing waves, and energy absorption efficiency are easily determined. For the verification of the proposed method, regular wave analysis is carried out, and numerical results are compared with those obtained from the frequency domain analysis using the two-dimensional boundary element method (2D-BEM). The results are also verified by the energy conservation principles. Through these verifications, it is shown that the proposed results strongly agree with the 2D-BEM results. Additionally, the real-time applicability is evaluated using the real-time factor (RTF). It is shown that the method achieves RTFs less than <span><math><mrow><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mo>−</mo><mn>2</mn></mrow></msup></mrow></math></span>; computational efficiency and practical feasibility are demonstrated.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104539"},"PeriodicalIF":4.3,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Feasibility assessment of enhancing permeability and stability in marine hydrate reservoirs with dual-enhanced stimulation: Slurry-sediment cementation characteristics","authors":"Fang Jin,&nbsp;Feng Huang,&nbsp;Guobiao Zhang,&nbsp;Bing Li,&nbsp;Yanchao Liu,&nbsp;Jianguo Lv","doi":"10.1016/j.apor.2025.104545","DOIUrl":"10.1016/j.apor.2025.104545","url":null,"abstract":"<div><div>Natural gas hydrate reservoirs in the South China Sea exhibit weak cementation, low strength, and low permeability, which severely restricts their commercial viability. To overcome these challenges, we propose an innovative dual-enhanced stimulation method involving slurry injection via splitting grouting. This slurry undergoes <em>in-situ</em> solidification, forming porous, high-strength, and high-permeability channels. The method's success hinges on understanding cementation patterns between the slurry and reservoir sediments, along with the permeability dynamics at the cementation interface. This study explored the microscopic features of the slurry-sediment cementation interface and evaluated changes in permeability nearby and within the slurry-sediment composite. It was observed that during the solidification process, the slurry invaded the sediments, resulting in an interface thickness more than 55µm. This invasion altered the pore structure of the sediment at the interface, reducing its porosity by more than 40 %, which in turn decreased gas permeability and damaged the permeability of the slurry-sediment coupled sample. After consolidation, the permeability damage of the coupled sample reached about 75 %, but it decreased to 27 % with the discharge of the permeability-enhancer in the slurry. Additionally, the evaluation of the pressure drop coefficient revealed that hydrate reservoirs stimulated with polyurethane slurry exhibit superior permeability compared to those transformed with guar gum fracturing fluid and pure water. This suggests that the dual-enhanced stimulation slurry causes minimal damage to reservoir permeability, demonstrating its feasibility in enhancing both permeability and strength of the reservoir. This study presents a novel stimulation method for the safe and efficient extraction of marine hydrates.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104545"},"PeriodicalIF":4.3,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143716093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural responses of offshore multi-body floating photovoltaic array under different connection conditions","authors":"Tao Zou ,&nbsp;Jian Jiang ,&nbsp;Haijun Li ,&nbsp;Junfeng Du ,&nbsp;Longbin Tao","doi":"10.1016/j.apor.2025.104544","DOIUrl":"10.1016/j.apor.2025.104544","url":null,"abstract":"<div><div>The connector design plays a pivotal role in ensuring the structural integrity and operational efficiency of offshore floating photovoltaic (FPV) systems. This study aims to systematically investigate the impact of various connection types (rigid, rubber, hinged, and flexible) on the hydrodynamic response of offshore FPV arrays, as well as on the structural responses of their connectors. Firstly, a single-float model was developed, and the hydrodynamic coefficients necessary for the time-domain analysis were meticulously derived using frequency-domain methods. Subsequently, a 3 × 3 FPV array model was constructed, including the connectors with specifications tailored to the stiffness and constraints of the four distinct connection types. Finally, a comparative analysis was conducted on the motion responses of the three representative modules (central, edge, and corner), along with the corresponding connectors’ responses. This study demonstrates that floats interconnected by rigid connectors are most significantly influenced by the surrounding floats. The outer floats, in conjunction with their connectors, constitute an outer-frame integrity phenomenon that plays a critical role in maintaining the array stability. Furthermore, the fatigue cycles experienced by the connectors attached to corner modules exhibited an increased sensitivity to the incident wave angle, highlighting the importance of precise wave direction considerations.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104544"},"PeriodicalIF":4.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control co-design for wave energy systems","authors":"John V. Ringwood","doi":"10.1016/j.apor.2025.104514","DOIUrl":"10.1016/j.apor.2025.104514","url":null,"abstract":"<div><div>Control co-design (CCD) has become a powerful paradigm in the total optimisation of the dynamics of a system against a defined performance goal. Given the impact of control on wave energy systems, including significant effects on motion and energy capture performance, it is imperative that controller and system are optimised together to maximise (economic) system performance. There are a number of design aspects that can usefully be addressed by CCD in wave energy systems, including device geometry, mooring configuration, power take-off (PTO) parameters, and array layout. A number of these design aspects present significant computational challenges and, as a result, wave energy CCD studies typically address a single design aspect at a time. This paper examines the useful roles that CCD can play in wave energy systems, important criteria to consider, and the potential interaction between individual wave energy CCD aspects.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104514"},"PeriodicalIF":4.3,"publicationDate":"2025-03-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis and experimental research on the coupled motion of the foot and paddle of crab-like robot based on biological observation","authors":"Shihao Hu ,&nbsp;Mingfei Xin ,&nbsp;Siqi Li ,&nbsp;Jiawei Li ,&nbsp;Gang Wang ,&nbsp;Shuo Zhang ,&nbsp;Xi Chen","doi":"10.1016/j.apor.2025.104524","DOIUrl":"10.1016/j.apor.2025.104524","url":null,"abstract":"<div><div>Shallow water regions, characterized by complex and varied terrain as well as dense aquatic vegetation, pose challenges for traditional propeller-based propulsion systems, which can damage seabed substrates and become entangled with aquatic plants. Amphibious bionic robots, with their remarkable environmental adaptability, have emerged as a research focus for operations in shoal environments. Drawing inspiration from the walking behavior of Portunus trituberculatus (Portunus), this paper presents a walking method for a crab-like robot that incorporates a coupled foot-paddle motion. Using the direct linear transformation (DLT) algorithm, we have captured the motion trajectories of the swimming paddles (in both heart-shaped and figure-eight patterns) during the underwater locomotion of Portunus. A hydrodynamic simulation environment was established, and the robot model was simplified. Based on the simulation results, we analyzed the influence of coupled foot-paddle motion on the robot’s force distribution from three perspectives: pressure distribution maps of the swimming paddles, force curves, and vortex diagrams. Experimental validation confirmed the effectiveness of the coupled foot-paddle motion strategy in enhancing underwater walking speed, with the figure-eight flapping mode achieving an average speed increase of 11.5% and the heart-shaped flapping mode achieving an average speed increase of 9.8%. Furthermore, in terms of stability, the coupled foot-paddle motion with heart-shaped flapping exhibited superior performance.The experimental results verify the effectiveness of the foot-paddle coupled motion strategy proposed in this paper, which provides a research basis for bionic robot composite propulsion research.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104524"},"PeriodicalIF":4.3,"publicationDate":"2025-03-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143704771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"DCNet: A data-driven framework for DVL calibration","authors":"Zeev Yampolsky,&nbsp;Itzik Klein","doi":"10.1016/j.apor.2025.104525","DOIUrl":"10.1016/j.apor.2025.104525","url":null,"abstract":"<div><div>Autonomous underwater vehicles (AUVs) are underwater robotic platforms used in a variety of applications. An AUV’s navigation solution relies heavily on the fusion of inertial sensors and Doppler velocity logs (DVL), where the latter delivers accurate velocity updates. To ensure accurate navigation, a DVL calibration is undertaken before the mission begins to estimate its error terms. During calibration, the AUV follows a complex trajectory and employs nonlinear estimation filters to estimate error terms. In this paper, we introduce DCNet, a data-driven framework that utilizes a two-dimensional convolution kernel in an innovative way. Using DCNet and our proposed DVL error model, we offer a rapid calibration procedure. This can be applied to a trajectory with a nearly constant velocity. To train and test our proposed approach a dataset of 276 min long with real DVL recorded measurements was used. We demonstrated an average improvement of 70% in accuracy and 80% improvement in calibration time, compared to the baseline approach, with a low-performance DVL. As a result of those improvements, an AUV employing a low-cost DVL, can achieve higher accuracy, shorter calibration time, and apply a simple nearly constant velocity calibration trajectory. Our results also open up new applications for marine robotics utilizing low-cost, high-accurate DVLs.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104525"},"PeriodicalIF":4.3,"publicationDate":"2025-03-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143686664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Wave heights over Canadian oceans: Tempo-spatial variations and climate-oscillation impacts based on macroscale spatially-extrapolative retrieval from altimetric ensembles","authors":"Cong Dong ,&nbsp;Gordon Huang ,&nbsp;Guanhui Cheng ,&nbsp;Yanpeng Cai","doi":"10.1016/j.apor.2025.104517","DOIUrl":"10.1016/j.apor.2025.104517","url":null,"abstract":"<div><div>Estimation and analyses of significant wave heights (SWHs) are crucial to climate research, ocean engineering and other applications, with satellite retrieval serving as a fundamental approach. However, few studies attempt to extrapolate SWH models across buoy grids to retrieve ungauged-grid SWHs from multiple altimeters at macroscales, or examine variations of extreme SWHs in relation to climate oscillations, particularly in the Canadian context. To fill these gaps, we develop a macroscale spatially-extrapolative ensemble wave-height retrieval and analysis (MEERA) method to retrieve SWHs from multi-mission satellite altimetry and reveal tempo-spatial characteristics of SWHs means and extremes as well as their variations with climate oscillations. The method is applied across all Canadian waters. According to modeling results, MEERA significantly enhances consistency and accuracy of retrieved SWHs (especially in coastal areas), e.g., reducing biases of conventional methods by over 98%. From 1985 to 2020, waves were strongly seasonal and regional, which drop from winter (1.45 m) to summer (1.17 m) and tend to decline northward. SWHs tend to decrease in mid-eastern regions (e.g., Hudson Bay, Davis Strait and Gulf of St Lawrence) and increase in Canadian Atlantic, Pacific, and Arctic. Across all Canadian waters, climate indices regarding precipitation, e.g., the NBRA (Northeast Brazil Rainfall Anomaly) index, pose the strongest impacts on extreme SWHs compared with others. In Pacific and Atlantic, spatial patterns of winter SWH extremes are associated with negative NAO (North Atlantic Oscillation). El Niño might increase SWHs extremes over the Pacific and Arctic, while decreasing them over mid-eastern regions. This study advances macroscale SWH estimation and analysis, enhancing the understanding of SWH characteristics and their variations across Canada under climate change.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104517"},"PeriodicalIF":4.3,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143686653","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plastic optical fiber sensors for mooring lines monitoring in floating wind turbines: A reliability study of OTDR measurement","authors":"Romain Grangeat ,&nbsp;Marion Girard ,&nbsp;Cyril Lupi ,&nbsp;Dominique Leduc ,&nbsp;Frédéric Jacquemin","doi":"10.1016/j.apor.2025.104541","DOIUrl":"10.1016/j.apor.2025.104541","url":null,"abstract":"<div><div>This study investigates the use of POF (Plastic Optical Fibers) for mooring lines monitoring in floating wind turbines. Focusing on their mechanical adaptability and optical performance in marine environments. Optical attenuation measurement are employed to determine integrity of POFs under mechanical stresses such as tension and torsion, as well as during prolonged water immersion at ambient temperature. Key findings demonstrate a high deformation capacity of POFs (up to 70 % strain), with negligible loss in light transmission under mechanical stresses in tension and torsion. Additionally, water absorption was found to have a limited impact on optical attenuation, even after extended immersion. These results confirm the suitability in POFs for mooring lines monitoring in floating wind turbines. Furthermore, elongation measurements performed on POFs of up to 100 meters in length validated the feasibility of monitoring strain using both transmission and reflection OTDR (Optical Time Domain Reflectometer) measurement. The results highlight POFs as cost-effective, durable sensors capable of addressing the high-strain demands of mooring line applications.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104541"},"PeriodicalIF":4.3,"publicationDate":"2025-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143686663","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An improved direct forcing immersed boundary method for floating body simulations in waves","authors":"Ahmet Soydan,&nbsp;Widar W. Wang,&nbsp;Hans Bihs","doi":"10.1016/j.apor.2025.104523","DOIUrl":"10.1016/j.apor.2025.104523","url":null,"abstract":"<div><div>This paper introduces a novel direct forcing immersed boundary method tailored to simulate nonlinear interactions between ocean waves and arbitrarily complex free-floating structures. Within an open-source hydrodynamic framework, we couple the fluid–structure interaction (FSI) algorithm with the two-phase flow solver through forcing at the fluid–solid interface. We substantially enhance this coupling process by altering the density interpolation method, significantly reducing the interface smearing region, which improves both the stability and accuracy of the fluid flow in the vicinity of the floating objects. The tracking of the fluid–solid interface in the Eulerian domain is based on a level set function, thus avoiding the need for dynamically moving or overset meshes and greatly simplifying the mesh generation process. Rigid body dynamics are implemented using Euler parameters and Hamiltonian mechanics, allowing for arbitrarily large motions of the floating body. The presented approach is tested and validated with several 2D and 3D problems, including a full-scale simulation of a floating semi-submersible offshore wind turbine in waves. All numerical results demonstrate the accuracy and robustness of the new method, highlighting its potential as an outstanding alternative to existing numerical approaches for realistic floating-body simulations in waves.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104523"},"PeriodicalIF":4.3,"publicationDate":"2025-03-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143686651","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Prediction of thrust bearing parameters in shafting-shell coupling system from frequency response function with artificial neural networks","authors":"Cong Zhang ,&nbsp;Yaqi Tian ,&nbsp;Yifan Xie ,&nbsp;Lei Yang","doi":"10.1016/j.apor.2025.104528","DOIUrl":"10.1016/j.apor.2025.104528","url":null,"abstract":"<div><div>The thrust bearing is a critical component for power transmission and vibration coupling between the propulsion shafting and the shell of the underwater vehicle. Identifying thrust bearing parameters is crucial for studying the vibration and diagnosing bearing faults of the underwater vehicle. In this study, key information was extracted from the frequency response function (FRF) of the shafting-shell coupling system, and then the artificial neural network (ANN) was used to predict the stiffness and damping of the thrust bearing. The dataset used to train the ANN came from the analytical dynamic model of the shafting-shell system. This analytical approach offers high computational efficiency, making it feasible to generate a substantial amount of training data within a reasonable timeframe. In the analytical dynamic model, the shell was modeled using the Flügge theory, while the shafting system was modeled using the Euler-Bernoulli beam theory. The bearings were simplified as a spring-damping system to represent the connection between the shafting system and the shell. This study employed two ANN algorithms: Backpropagation Neural Network (BP) and Genetic Algorithm-optimized Backpropagation Neural Network (GABP). The results indicate that both BP and GABP effectively predict the stiffness and damping of thrust bearings. Moreover, GABP demonstrates more stable prediction results with smaller prediction errors. The proposed method for predicting thrust bearing parameters leverages features from the FRF to train the ANN, which provides good robustness, maintaining effective results even when the signal-to-noise ratio of the FRF is reduced. The thrust bearing parameter prediction model was validated through experiment, confirming the effectiveness of using ANNs to predict bearing parameters in shafting-shell coupling systems from FRF. This study realizes efficient prediction of bearing parameters, providing a reference for vibration reduction, operational state monitoring, and fault diagnosis of underwater vehicles.</div></div>","PeriodicalId":8261,"journal":{"name":"Applied Ocean Research","volume":"158 ","pages":"Article 104528"},"PeriodicalIF":4.3,"publicationDate":"2025-03-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143686652","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}