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2025, 39(3): 383 -394
doi: 10.1007/s13344-025-0030-9
[Abstract](0)
Abstract:
In recent years, with the development of technologies such as the Internet of Things (IoT), big data and cloud computing, digital twin technology has gradually been applied in marine research. The digital twin realizes real-time monitoring, analysis and optimization of the state and behavior of a physical object or system by creating a virtual model. Research shows that digital twin technology has extensive application potential in ship design, marine resource development, marine equipment engineering design and optimization, marine ecological protection and early warning of disasters. Although digital twin technology has great potential in marine research, it also faces many challenges, including the complexity of data acquisition and processing, the accuracy and real-time performance of model construction, and the need for multidisciplinary cross-integration. An in-depth analysis of the technical bottlenecks and future development directions will provide an important reference for subsequent research and promote the further application and development of digital twin technology in marine research.
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2025, 39(3): 395 -409
doi: 10.1007/s13344-025-0031-8
[Abstract](0)
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A three-dimensional panel method is developed to investigate the seakeeping performance of two parallel ships advancing in head and oblique waves. In this method, the fluid domain is partitioned into two regions by introducing a virtual control surface. In the inner part, the Taylor expansion boundary element method is used, whose kernel function is the Rankine source; in the outer part, the free surface Green function with the forward speed effect considered is adopted. The velocity potentials and normal velocities on the virtual control surface are equal for the inner and outer domains. Moreover, the numerical estimation method for viscous roll damping recommended by the ITTC is included in the present method. This hybrid method is validated through the previously measured motions of two ship models, and the present numerical results are in good agreement with those of the experiments. Furthermore, the influences of longitudinal distances and wave heading angles on six-degree-of-freedom motions and the hydrodynamic interaction between the present two ship models are discussed in detail.
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2025, 39(3): 410 -425
doi: 10.1007/s13344-025-0032-7
[Abstract](0)
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The integrated systems of unmanned surface vehicles (USVs) and remotely operated vehicles (ROVs) have been extensively applied in marine exploration and seabed coverage. However, the simultaneous navigation of USV-ROV systems is frequently limited by strong disturbances induced by waves or currents. This paper develops a novel rigid-flexible coupling multibody dynamic model that incorporates disturbances of variable-length marine cables with geometrically nonlinear motion. A hybrid Lagrangian-Eulerian absolute nodal coordinate formulation (ANCF) element is developed to accurately model subsea cables which undergo significant overall motion, substantial deformation, and mass flow during the deployment of underwater equipment. Furthermore, the governing equations of the coupled USV-umbilical-ROV system are derived, considering wave-induced forces and current disturbances. A numerical solver based on the Newmark-beta method is proposed, along with an adaptive meshing technique near the release point. After validating three experimental cases, the cable disturbances at both the USV and ROV ends—caused by ocean currents, heave motion, and simultaneous navigation—are comprehensively compared and evaluated. Finally, it is demonstrated that a PD controller with disturbance compensation can enhance the simultaneous navigation performance of USV-ROV systems.
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2025, 39(3): 426 -440
doi: 10.1007/s13344-025-0033-6
[Abstract](0)
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Internal solitary waves (ISWs) are a common phenomenon beneath the ocean surface and represent a significant environmental hazard that must be considered for the safe navigation of submersibles. A numerical simulation model for the interaction of solitary waves with submersibles at a large scale has been developed. The Miyata-Choi-Camassa (MCC) equation serves as the basis for generating ISWs. The impacts of the submergence depth, wave amplitude, and advancing velocity on the motion response and load characteristics of the submersible are examined in detail. This study elucidates the governing laws and mechanisms underlying the impact of ISWs on submersibles. The research findings indicate that shorter distances to the undisturbed surface, higher wave amplitudes, and faster-advancing speeds result in greater effects on submersibles. For a submersible operating in the lower layer, both the alteration in density near the wave interface and the dynamic pressure induced by ISWs can reduce its lift, potentially resulting in a rapid descent. It is imperative to pay considerable attention to the impact of ISWs, as they have the potential to precipitate a loss of control of the submersible.
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2025, 39(3): 441 -454
doi: 10.1007/s13344-025-0081-y
[Abstract](0)
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This paper explores the phenomenon of fluid resonance occurring within a narrow gap between a vessel and a vertical wharf, taking ships berthing in front of a gravity wharf as the research background. Using the open-source software OpenFOAM®, a two-dimensional viscous-flow numerical wave flume was developed to simulate the fluid resonant motions induced by transient focused wave groups with different spectral peak periods and wave amplitudes. The results indicate that for all the incident focused wave amplitudes considered, the amplitudes of the free surface elevation in the gap, horizontal wave force and moment all exhibit a bimodal variation trend with increasing spectral peak period. The peak values of the above amplitude-period curve appear near the resonant period of the first and second harmonic components of the free surface elevation. However, the variation in the vertical wave force versus the spectral peak period presents different patterns. In addition, the first- to fourth-order harmonic components in the wave surface and forces are further examined via the four-phase combination method. The results show that the first- to second-order harmonic components play a dominant role in the overall amplitude.
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2025, 39(3): 455 -469
doi: 10.1007/s13344-025-0035-4
[Abstract](0)
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A piggyback pipeline is a special configuration of offshore pipelines for offshore oil and gas exploration and is characterized by the coupling of a large-diameter pipe with a small-diameter pipe. This study conducts a numerical investigation of the transverse VIV characteristics of a piggyback pipeline at low Reynolds numbers, as the vortex shedding modes and vibration characteristics can be accurately represented under laminar flow conditions with minimal computational expense. The effects of influential factors, such as the mass ratio, position angle of the small pipe relative to the main pipe, and Reynolds number, on the VIV amplitude, frequency, vibration center, and mean lift coefficient are specifically examined. The results indicate that the mass ratio has a limited effect on the maximum VIV amplitude. However, as the mass ratio decreases, the lock-in region expands, and the vibration center of the piggyback pipeline deviates further from its original position. The VIV amplitude is minimized, and the lock-in region is the narrowest at a position angle of 45°, whereas the vibration center reaches its maximum displacement at a position angle of 135°. As the Reynolds number increases, the VIV amplitude slightly increases, accompanied by convergence of the vibration center toward its initial position. The mean lift coefficient and wake vortices are also analyzed to establish a connection with the vibration characteristics of the piggyback pipeline. The optimal configuration of the piggyback pipeline is also proposed on the basis of the present numerical results.
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2025, 39(3): 470 -483
doi: 10.1007/s13344-025-0080-z
[Abstract](0)
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The integrated system composed of wave energy converters and floating wind turbines offers substantial potential for reducing the levelized cost of energy (LCOE) by sharing the infrastructure, mooring system, substations and cables. This paper proposes an integrated system consisting of a semi-submersible wind turbine platform and three WaveStar flap-type wave energy converters. The coupled motion model of the integrated system is established and validated on the basis of viscously corrected potential flow theory. This study investigates the influence of two key parameters, the arm length and hinge points of flap-type wave energy converters, on system performance. The results reveal that variations in the arm length of flap-type wave energy converters (WECs) are the primary determinants of the integrated system’s dynamic characteristics, whereas changes in hinge points predominantly affect device power generation. Additionally, incorporating WECs reduces the pitch and heave motions of the platform within a specific wave frequency range, thereby enhancing the energy output of the integrated system at the operational sea site. The performance of this hybrid system at a selected sea site is further assessed via the proposed aero-hydroservo coupling simulations.
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2025, 39(3): 484 -492
doi: 10.1007/s13344-025-0036-3
[Abstract](0)
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The composite bucket foundations of offshore wind turbines penetrate minimally into the seabed, making local scour a significant threat to wind turbine stability. This study develops a physical model to examine local scour patterns around a novel mono-column composite bucket foundation (MCCBF) under unidirectional flows. The experiments reveal that under weak-flow conditions, no significant scour pits develop at the front or lateral sides of the MCCBF, while two distinct scour pits form behind the lateral sides. Under strong-flow conditions, substantial scour pits emerge at both frontal and lateral sides of the bucket foundation, with two scour pits extending downstream on either side. The research demonstrates that both the range and depth of local scour increase with higher flow velocity and decreasing water depth, though the mechanisms influencing local scour around the MCCBF prove more complex than those affecting monopiles. The distinctive structural features of the MCCBF necessitate particular consideration of effects related to bucket foundation exposure. The study concludes by proposing an empirical formula for predicting maximum scour depth around the MCCBF.
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2025, 39(3): 493 -503
doi: 10.1007/s13344-025-0037-2
[Abstract](0)
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Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experiments under unidirectional flow, bidirectional flow, and wave-current interactions with different flow directions around the pile group foundation were first conducted to investigate the development of scour around the pile group foundation. Additionally, a three-dimensional scour numerical model was established via the open-source software REEF3D to simulate the flow field and scour around the prototype-scale foundation. The impact of flow on scour was discussed. Under unidirectional flow, scour equilibrium was reached more quickly, with the maximum scour depth reaching approximately 1.2 times the pile diameter and the extent of the scour hole spanning about 4.9 times the pile diameter. Compared with those under unidirectional flow, the scour depths under combinations of currents and waves, as well as bidirectional flow, were slightly smaller. However, the morphology of scour holes was more uniform and symmetrical. The numerical simulation results show good agreement with the experimental data, demonstrating the impact of varying flow directions on the velocity distribution around the foundation, the morphology of scour holes, and the location of the maximum scour depth.
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2025, 39(3): 504 -517
doi: 10.1007/s13344-025-0038-1
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A numerical investigation on the effectiveness of the actuator disc method in producing the interactions of multiple tidal stream devices via the 3D-RANS finite element model Telemac3D is explored. The methodology for the implementation of the source term to represent an array of 20 m rotor diameter turbines deployed in an idealized channel is reviewed and discussed in detail. Flow interactions between multiple turbines are investigated for a single row arrangement with only two turbines and a two row arrangement containing three turbines. The results demonstrate that the non-hydrostatic solver shows better agreement when validated against published experimental data. Notably, the mesh density at the device location can strongly influence the simulated thrust from the disc. Although the actuator disc model can generally replicate the wake interactions well, the results indicate that it cannot accurately characterize the flow for regions with high turbulences. While a model setup with the largest lateral spacing (1.5D) demonstrates excellent agreement with the experimental data, the 0.5D model (smallest gap) deviates by up to 25%. These findings demonstrate the effectiveness of the applied source term in reproducing the wake profile, which is comparable with the published data, and highlight the inherent nature of the RANS and actuator disc models.
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2025, 39(3): 518 -528
doi: 10.1007/s13344-025-0039-0
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Grouting represents a reliable method for strengthening fractured rock masses and preventing seawater infiltration in subsea tunnel engineering. However, grouting composites are continuously subjected to harsh marine environments, experiencing both chemical and physical effects from high-concentration erosive seawater ions, elevated water pressure, and complex flow fields. This multi-factor erosion deterioration diminishes the waterproofing capabilities of grouting composites and threatens the service life of subsea tunnel linings. To investigate the erosion deteriortion mechanism induced by sulfate, erosion weakening experiments were conducted using a seawater flow simulation device. The research examined the compressive strength and permeability coefficient of grouting composites under different erosion durations, water-cement ratios, and grouting pressures. In the later stages of the experiment, the strength of grouting composites in the static water erosion control group (SEG) and dynamic water erosion group (DEG) decreased by 31.2% and 18.8%, respectively, compared to the freshwater control group (FG). Futhermore, the permeability coefficient exhibited significant increases. Subsequent microscopic analyses of the eroded grouting composites were performed. This research elucidated the erosion-weakening mechanism of grouting composites subjected to sulfate-induced degradation in complex marine environments. The study emphasizes the critical role of erosion resistance and durability in design and implementation. From practical perspective, this work establishes a foundation for developing enhanced strategies to improve the long-term performance and integrity of grouting composites in subsea tunnel applications.
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2025, 39(3): 529 -540
doi: 10.1007/s13344-025-0040-7
[Abstract](0)
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Under severe sea conditions, wave slamming on ships and marine engineering structures may lead to structural damage and casualties. Moreover, the strong nonlinearity inherent in the wave slamming process significantly limits the accuracy of numerical analyses and finite element simulations. Therefore, this paper takes a new type of floating wind turbine as an example and performs a physical model test on the wave slamming characteristics of this floating wind turbine. Based on a 1:50 model of the PivotBuoy floating wind turbine, an experimental study is performed under the combined effects of wind-wave loads on the peak pressure, duration, and pressure distribution of slamming. First, two sets of mooring systems, the combined scheme and the full mooring chain scheme, are designed to conduct a series of experimental studies of model slamming under different wind and wave incidence angles, wave heights, and wave periods. By doing so, the slamming characteristics of the wind turbine can be obtained. Moreover, to solve the problem of the large pitch motion response of the prototype wind turbine, a set of vertically oscillating structures is designed, and the slamming pressure characteristics of the optimized model are also investigated through model tests.
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2025, 39(3): 541 -547
doi: 10.1007/s13344-025-0057-y
[Abstract](0)
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Recently, during the investigations on planetary oceans, Hirota-Satsuma-Ito-type models have been developed. In this paper, for a (2+1)-dimensional generalized variable-coefficient Hirota-Satsuma-Ito system describing the fluid dynamics of shallow-water waves in an open ocean, non-characteristic movable singular manifold and symbolic computation enable an oceanic auto-Bäcklund transformation with three sets of the oceanic solitonic solutions. The results rely on the oceanic variable coefficients in that system. Future oceanic observations might detect some nonlinear features predicted in this paper, and relevant oceanographic insights might be expected.
2025, 39(3): 548 -561
doi: 10.1007/s13344-025-0044-3
[Abstract](0)
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Maritime target recognition and image perception enhancement are gradually being promoted and applied in ocean engineering. This paper proposes the attentional multi-pixel fusion (AMF) algorithm for the intelligent navigation of unmanned surface vessels (USVs). The algorithm preprocesses the image pixel matrix in blocks, computes the mapping between regional and full-pixel matrices, and adaptively equalizes the mapping weights via a Gaussian-fuzzy matrix. This approach guarantees the preservation of the target contour and texture information. Compared with five classic enhancement algorithms, the AMF algorithm improves the peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM). Experimental validation via YOLOv8 for maritime target detection demonstrates 2.1% and 2.4% improvements in the evaluation indices over training on 4000 original images, with shorter training times and lower confusion rates. In maritime target ranging, the AMF algorithm, coupled with the ISR method, exhibits the lowest improved stereo ranging mean absolute error and standard deviation values and higher similarity between the regional and full-pixel matrices. In summary, the AMF algorithm excels in target detection and ranging, offering promising applications in ocean engineering, such as marine resource exploitation, path planning, and intelligent collaboration among unmanned vessels.
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2025, 39(3): 562 -572
doi: 10.1007/s13344-025-0041-6
[Abstract](0)
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This study investigates the load-bearing capacity of open-ended pipe piles in sandy soil, with a specific focus on the impact of soil plug constraints at four levels (no plug, 25% plug, 50% plug, and full plug). Leveraging a dataset comprising open-ended pipe piles with varying geometrical and geotechnical properties, this research employs shallow neural network (SNN) and deep neural network (DNN) models to predict plugging conditions for both driven and pressed installation types. This paper underscores the importance of key parameters such as the settlement value, applied load, installation type, and soil configuration (loose, medium, and dense) in accurately predicting pile settlement. These findings offer valuable insights for optimizing pile design and construction in geotechnical engineering, addressing a longstanding challenge in the field. The study demonstrates the potential of the SNN and DNN models in precisely identifying plugging conditions before pile driving, with the SNN achieving R2 values ranging from 0.444 to 0.711 and RMSPE values ranging from 24.621% to 48.663%, whereas the DNN exhibits superior performance, with R2 values ranging from 0.815 to 0.942 and RMSPE values ranging from 4.419% to 10.325%. These results have significant implications for enhancing construction practices and reducing uncertainties associated with pile foundation projects in addition to leveraging artificial intelligence tools to avoid long experimental procedures.
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Image Enhancement by Improving the Dark Channel Prior Method for Underwater Concrete Crack Detection
2025, 39(3): 573 -584
doi: 10.1007/s13344-025-0061-2
[Abstract](0)
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Health monitoring of underwater concrete facility systems is important in civil engineering. Unlike conventional manual inspection techniques, digital image processing offers a more convenient and effective approach, becoming an indispensable tool for structural inspection. Cracks, which are pervasive defects, are a central focus of structural deterioration research. However, the complexity of the marine environment poses challenges to underwater visibility. In this study, the underwater environment under controlled laboratory conditions is replicated, where varying turbidity and illumination conditions and images of concrete cracks are captured. An approach combining a defogging algorithm with guided and fast guided filtering techniques is proposed to enhance both natural underwater images and crack images captured through experimental photography. When applied to turbid crack images captured under two different suspension conditions, the method increases the information entropy (IE) by 32.92% and 17.92% and the underwater color image quality evaluation (UCIQE) by 35.76% and 18.36%, respectively. These results demonstrate its efficiency in enhancing image definition. The findings of this study could significantly impact the practical applications of image visualization and evaluation for underwater concrete cracks.
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Display Method:
Display Method: |
2025, 39(3): 383 -394
doi: 10.1007/s13344-025-0030-9
[Abstract](0)
Abstract:
In recent years, with the development of technologies such as the Internet of Things (IoT), big data and cloud computing, digital twin technology has gradually been applied in marine research. The digital twin realizes real-time monitoring, analysis and optimization of the state and behavior of a physical object or system by creating a virtual model. Research shows that digital twin technology has extensive application potential in ship design, marine resource development, marine equipment engineering design and optimization, marine ecological protection and early warning of disasters. Although digital twin technology has great potential in marine research, it also faces many challenges, including the complexity of data acquisition and processing, the accuracy and real-time performance of model construction, and the need for multidisciplinary cross-integration. An in-depth analysis of the technical bottlenecks and future development directions will provide an important reference for subsequent research and promote the further application and development of digital twin technology in marine research.
In recent years, with the development of technologies such as the Internet of Things (IoT), big data and cloud computing, digital twin technology has gradually been applied in marine research. The digital twin realizes real-time monitoring, analysis and optimization of the state and behavior of a physical object or system by creating a virtual model. Research shows that digital twin technology has extensive application potential in ship design, marine resource development, marine equipment engineering design and optimization, marine ecological protection and early warning of disasters. Although digital twin technology has great potential in marine research, it also faces many challenges, including the complexity of data acquisition and processing, the accuracy and real-time performance of model construction, and the need for multidisciplinary cross-integration. An in-depth analysis of the technical bottlenecks and future development directions will provide an important reference for subsequent research and promote the further application and development of digital twin technology in marine research.
2025, 39(3): 395 -409
doi: 10.1007/s13344-025-0031-8
[Abstract](0)
Abstract:
A three-dimensional panel method is developed to investigate the seakeeping performance of two parallel ships advancing in head and oblique waves. In this method, the fluid domain is partitioned into two regions by introducing a virtual control surface. In the inner part, the Taylor expansion boundary element method is used, whose kernel function is the Rankine source; in the outer part, the free surface Green function with the forward speed effect considered is adopted. The velocity potentials and normal velocities on the virtual control surface are equal for the inner and outer domains. Moreover, the numerical estimation method for viscous roll damping recommended by the ITTC is included in the present method. This hybrid method is validated through the previously measured motions of two ship models, and the present numerical results are in good agreement with those of the experiments. Furthermore, the influences of longitudinal distances and wave heading angles on six-degree-of-freedom motions and the hydrodynamic interaction between the present two ship models are discussed in detail.
A three-dimensional panel method is developed to investigate the seakeeping performance of two parallel ships advancing in head and oblique waves. In this method, the fluid domain is partitioned into two regions by introducing a virtual control surface. In the inner part, the Taylor expansion boundary element method is used, whose kernel function is the Rankine source; in the outer part, the free surface Green function with the forward speed effect considered is adopted. The velocity potentials and normal velocities on the virtual control surface are equal for the inner and outer domains. Moreover, the numerical estimation method for viscous roll damping recommended by the ITTC is included in the present method. This hybrid method is validated through the previously measured motions of two ship models, and the present numerical results are in good agreement with those of the experiments. Furthermore, the influences of longitudinal distances and wave heading angles on six-degree-of-freedom motions and the hydrodynamic interaction between the present two ship models are discussed in detail.
2025, 39(3): 410 -425
doi: 10.1007/s13344-025-0032-7
[Abstract](0)
Abstract:
The integrated systems of unmanned surface vehicles (USVs) and remotely operated vehicles (ROVs) have been extensively applied in marine exploration and seabed coverage. However, the simultaneous navigation of USV-ROV systems is frequently limited by strong disturbances induced by waves or currents. This paper develops a novel rigid-flexible coupling multibody dynamic model that incorporates disturbances of variable-length marine cables with geometrically nonlinear motion. A hybrid Lagrangian-Eulerian absolute nodal coordinate formulation (ANCF) element is developed to accurately model subsea cables which undergo significant overall motion, substantial deformation, and mass flow during the deployment of underwater equipment. Furthermore, the governing equations of the coupled USV-umbilical-ROV system are derived, considering wave-induced forces and current disturbances. A numerical solver based on the Newmark-beta method is proposed, along with an adaptive meshing technique near the release point. After validating three experimental cases, the cable disturbances at both the USV and ROV ends—caused by ocean currents, heave motion, and simultaneous navigation—are comprehensively compared and evaluated. Finally, it is demonstrated that a PD controller with disturbance compensation can enhance the simultaneous navigation performance of USV-ROV systems.
The integrated systems of unmanned surface vehicles (USVs) and remotely operated vehicles (ROVs) have been extensively applied in marine exploration and seabed coverage. However, the simultaneous navigation of USV-ROV systems is frequently limited by strong disturbances induced by waves or currents. This paper develops a novel rigid-flexible coupling multibody dynamic model that incorporates disturbances of variable-length marine cables with geometrically nonlinear motion. A hybrid Lagrangian-Eulerian absolute nodal coordinate formulation (ANCF) element is developed to accurately model subsea cables which undergo significant overall motion, substantial deformation, and mass flow during the deployment of underwater equipment. Furthermore, the governing equations of the coupled USV-umbilical-ROV system are derived, considering wave-induced forces and current disturbances. A numerical solver based on the Newmark-beta method is proposed, along with an adaptive meshing technique near the release point. After validating three experimental cases, the cable disturbances at both the USV and ROV ends—caused by ocean currents, heave motion, and simultaneous navigation—are comprehensively compared and evaluated. Finally, it is demonstrated that a PD controller with disturbance compensation can enhance the simultaneous navigation performance of USV-ROV systems.
2025, 39(3): 426 -440
doi: 10.1007/s13344-025-0033-6
[Abstract](0)
Abstract:
Internal solitary waves (ISWs) are a common phenomenon beneath the ocean surface and represent a significant environmental hazard that must be considered for the safe navigation of submersibles. A numerical simulation model for the interaction of solitary waves with submersibles at a large scale has been developed. The Miyata-Choi-Camassa (MCC) equation serves as the basis for generating ISWs. The impacts of the submergence depth, wave amplitude, and advancing velocity on the motion response and load characteristics of the submersible are examined in detail. This study elucidates the governing laws and mechanisms underlying the impact of ISWs on submersibles. The research findings indicate that shorter distances to the undisturbed surface, higher wave amplitudes, and faster-advancing speeds result in greater effects on submersibles. For a submersible operating in the lower layer, both the alteration in density near the wave interface and the dynamic pressure induced by ISWs can reduce its lift, potentially resulting in a rapid descent. It is imperative to pay considerable attention to the impact of ISWs, as they have the potential to precipitate a loss of control of the submersible.
Internal solitary waves (ISWs) are a common phenomenon beneath the ocean surface and represent a significant environmental hazard that must be considered for the safe navigation of submersibles. A numerical simulation model for the interaction of solitary waves with submersibles at a large scale has been developed. The Miyata-Choi-Camassa (MCC) equation serves as the basis for generating ISWs. The impacts of the submergence depth, wave amplitude, and advancing velocity on the motion response and load characteristics of the submersible are examined in detail. This study elucidates the governing laws and mechanisms underlying the impact of ISWs on submersibles. The research findings indicate that shorter distances to the undisturbed surface, higher wave amplitudes, and faster-advancing speeds result in greater effects on submersibles. For a submersible operating in the lower layer, both the alteration in density near the wave interface and the dynamic pressure induced by ISWs can reduce its lift, potentially resulting in a rapid descent. It is imperative to pay considerable attention to the impact of ISWs, as they have the potential to precipitate a loss of control of the submersible.
2025, 39(3): 441 -454
doi: 10.1007/s13344-025-0081-y
[Abstract](0)
Abstract:
This paper explores the phenomenon of fluid resonance occurring within a narrow gap between a vessel and a vertical wharf, taking ships berthing in front of a gravity wharf as the research background. Using the open-source software OpenFOAM®, a two-dimensional viscous-flow numerical wave flume was developed to simulate the fluid resonant motions induced by transient focused wave groups with different spectral peak periods and wave amplitudes. The results indicate that for all the incident focused wave amplitudes considered, the amplitudes of the free surface elevation in the gap, horizontal wave force and moment all exhibit a bimodal variation trend with increasing spectral peak period. The peak values of the above amplitude-period curve appear near the resonant period of the first and second harmonic components of the free surface elevation. However, the variation in the vertical wave force versus the spectral peak period presents different patterns. In addition, the first- to fourth-order harmonic components in the wave surface and forces are further examined via the four-phase combination method. The results show that the first- to second-order harmonic components play a dominant role in the overall amplitude.
This paper explores the phenomenon of fluid resonance occurring within a narrow gap between a vessel and a vertical wharf, taking ships berthing in front of a gravity wharf as the research background. Using the open-source software OpenFOAM®, a two-dimensional viscous-flow numerical wave flume was developed to simulate the fluid resonant motions induced by transient focused wave groups with different spectral peak periods and wave amplitudes. The results indicate that for all the incident focused wave amplitudes considered, the amplitudes of the free surface elevation in the gap, horizontal wave force and moment all exhibit a bimodal variation trend with increasing spectral peak period. The peak values of the above amplitude-period curve appear near the resonant period of the first and second harmonic components of the free surface elevation. However, the variation in the vertical wave force versus the spectral peak period presents different patterns. In addition, the first- to fourth-order harmonic components in the wave surface and forces are further examined via the four-phase combination method. The results show that the first- to second-order harmonic components play a dominant role in the overall amplitude.
2025, 39(3): 455 -469
doi: 10.1007/s13344-025-0035-4
[Abstract](0)
Abstract:
A piggyback pipeline is a special configuration of offshore pipelines for offshore oil and gas exploration and is characterized by the coupling of a large-diameter pipe with a small-diameter pipe. This study conducts a numerical investigation of the transverse VIV characteristics of a piggyback pipeline at low Reynolds numbers, as the vortex shedding modes and vibration characteristics can be accurately represented under laminar flow conditions with minimal computational expense. The effects of influential factors, such as the mass ratio, position angle of the small pipe relative to the main pipe, and Reynolds number, on the VIV amplitude, frequency, vibration center, and mean lift coefficient are specifically examined. The results indicate that the mass ratio has a limited effect on the maximum VIV amplitude. However, as the mass ratio decreases, the lock-in region expands, and the vibration center of the piggyback pipeline deviates further from its original position. The VIV amplitude is minimized, and the lock-in region is the narrowest at a position angle of 45°, whereas the vibration center reaches its maximum displacement at a position angle of 135°. As the Reynolds number increases, the VIV amplitude slightly increases, accompanied by convergence of the vibration center toward its initial position. The mean lift coefficient and wake vortices are also analyzed to establish a connection with the vibration characteristics of the piggyback pipeline. The optimal configuration of the piggyback pipeline is also proposed on the basis of the present numerical results.
A piggyback pipeline is a special configuration of offshore pipelines for offshore oil and gas exploration and is characterized by the coupling of a large-diameter pipe with a small-diameter pipe. This study conducts a numerical investigation of the transverse VIV characteristics of a piggyback pipeline at low Reynolds numbers, as the vortex shedding modes and vibration characteristics can be accurately represented under laminar flow conditions with minimal computational expense. The effects of influential factors, such as the mass ratio, position angle of the small pipe relative to the main pipe, and Reynolds number, on the VIV amplitude, frequency, vibration center, and mean lift coefficient are specifically examined. The results indicate that the mass ratio has a limited effect on the maximum VIV amplitude. However, as the mass ratio decreases, the lock-in region expands, and the vibration center of the piggyback pipeline deviates further from its original position. The VIV amplitude is minimized, and the lock-in region is the narrowest at a position angle of 45°, whereas the vibration center reaches its maximum displacement at a position angle of 135°. As the Reynolds number increases, the VIV amplitude slightly increases, accompanied by convergence of the vibration center toward its initial position. The mean lift coefficient and wake vortices are also analyzed to establish a connection with the vibration characteristics of the piggyback pipeline. The optimal configuration of the piggyback pipeline is also proposed on the basis of the present numerical results.
2025, 39(3): 470 -483
doi: 10.1007/s13344-025-0080-z
[Abstract](0)
Abstract:
The integrated system composed of wave energy converters and floating wind turbines offers substantial potential for reducing the levelized cost of energy (LCOE) by sharing the infrastructure, mooring system, substations and cables. This paper proposes an integrated system consisting of a semi-submersible wind turbine platform and three WaveStar flap-type wave energy converters. The coupled motion model of the integrated system is established and validated on the basis of viscously corrected potential flow theory. This study investigates the influence of two key parameters, the arm length and hinge points of flap-type wave energy converters, on system performance. The results reveal that variations in the arm length of flap-type wave energy converters (WECs) are the primary determinants of the integrated system’s dynamic characteristics, whereas changes in hinge points predominantly affect device power generation. Additionally, incorporating WECs reduces the pitch and heave motions of the platform within a specific wave frequency range, thereby enhancing the energy output of the integrated system at the operational sea site. The performance of this hybrid system at a selected sea site is further assessed via the proposed aero-hydroservo coupling simulations.
The integrated system composed of wave energy converters and floating wind turbines offers substantial potential for reducing the levelized cost of energy (LCOE) by sharing the infrastructure, mooring system, substations and cables. This paper proposes an integrated system consisting of a semi-submersible wind turbine platform and three WaveStar flap-type wave energy converters. The coupled motion model of the integrated system is established and validated on the basis of viscously corrected potential flow theory. This study investigates the influence of two key parameters, the arm length and hinge points of flap-type wave energy converters, on system performance. The results reveal that variations in the arm length of flap-type wave energy converters (WECs) are the primary determinants of the integrated system’s dynamic characteristics, whereas changes in hinge points predominantly affect device power generation. Additionally, incorporating WECs reduces the pitch and heave motions of the platform within a specific wave frequency range, thereby enhancing the energy output of the integrated system at the operational sea site. The performance of this hybrid system at a selected sea site is further assessed via the proposed aero-hydroservo coupling simulations.
2025, 39(3): 484 -492
doi: 10.1007/s13344-025-0036-3
[Abstract](0)
Abstract:
The composite bucket foundations of offshore wind turbines penetrate minimally into the seabed, making local scour a significant threat to wind turbine stability. This study develops a physical model to examine local scour patterns around a novel mono-column composite bucket foundation (MCCBF) under unidirectional flows. The experiments reveal that under weak-flow conditions, no significant scour pits develop at the front or lateral sides of the MCCBF, while two distinct scour pits form behind the lateral sides. Under strong-flow conditions, substantial scour pits emerge at both frontal and lateral sides of the bucket foundation, with two scour pits extending downstream on either side. The research demonstrates that both the range and depth of local scour increase with higher flow velocity and decreasing water depth, though the mechanisms influencing local scour around the MCCBF prove more complex than those affecting monopiles. The distinctive structural features of the MCCBF necessitate particular consideration of effects related to bucket foundation exposure. The study concludes by proposing an empirical formula for predicting maximum scour depth around the MCCBF.
The composite bucket foundations of offshore wind turbines penetrate minimally into the seabed, making local scour a significant threat to wind turbine stability. This study develops a physical model to examine local scour patterns around a novel mono-column composite bucket foundation (MCCBF) under unidirectional flows. The experiments reveal that under weak-flow conditions, no significant scour pits develop at the front or lateral sides of the MCCBF, while two distinct scour pits form behind the lateral sides. Under strong-flow conditions, substantial scour pits emerge at both frontal and lateral sides of the bucket foundation, with two scour pits extending downstream on either side. The research demonstrates that both the range and depth of local scour increase with higher flow velocity and decreasing water depth, though the mechanisms influencing local scour around the MCCBF prove more complex than those affecting monopiles. The distinctive structural features of the MCCBF necessitate particular consideration of effects related to bucket foundation exposure. The study concludes by proposing an empirical formula for predicting maximum scour depth around the MCCBF.
2025, 39(3): 493 -503
doi: 10.1007/s13344-025-0037-2
[Abstract](0)
Abstract:
Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experiments under unidirectional flow, bidirectional flow, and wave-current interactions with different flow directions around the pile group foundation were first conducted to investigate the development of scour around the pile group foundation. Additionally, a three-dimensional scour numerical model was established via the open-source software REEF3D to simulate the flow field and scour around the prototype-scale foundation. The impact of flow on scour was discussed. Under unidirectional flow, scour equilibrium was reached more quickly, with the maximum scour depth reaching approximately 1.2 times the pile diameter and the extent of the scour hole spanning about 4.9 times the pile diameter. Compared with those under unidirectional flow, the scour depths under combinations of currents and waves, as well as bidirectional flow, were slightly smaller. However, the morphology of scour holes was more uniform and symmetrical. The numerical simulation results show good agreement with the experimental data, demonstrating the impact of varying flow directions on the velocity distribution around the foundation, the morphology of scour holes, and the location of the maximum scour depth.
Under the combination of currents and waves, seabed scour occurs around offshore wind turbine foundations, which affects the stability and safe operation of offshore wind turbines. In this study, physical model experiments under unidirectional flow, bidirectional flow, and wave-current interactions with different flow directions around the pile group foundation were first conducted to investigate the development of scour around the pile group foundation. Additionally, a three-dimensional scour numerical model was established via the open-source software REEF3D to simulate the flow field and scour around the prototype-scale foundation. The impact of flow on scour was discussed. Under unidirectional flow, scour equilibrium was reached more quickly, with the maximum scour depth reaching approximately 1.2 times the pile diameter and the extent of the scour hole spanning about 4.9 times the pile diameter. Compared with those under unidirectional flow, the scour depths under combinations of currents and waves, as well as bidirectional flow, were slightly smaller. However, the morphology of scour holes was more uniform and symmetrical. The numerical simulation results show good agreement with the experimental data, demonstrating the impact of varying flow directions on the velocity distribution around the foundation, the morphology of scour holes, and the location of the maximum scour depth.
2025, 39(3): 504 -517
doi: 10.1007/s13344-025-0038-1
[Abstract](0)
Abstract:
A numerical investigation on the effectiveness of the actuator disc method in producing the interactions of multiple tidal stream devices via the 3D-RANS finite element model Telemac3D is explored. The methodology for the implementation of the source term to represent an array of 20 m rotor diameter turbines deployed in an idealized channel is reviewed and discussed in detail. Flow interactions between multiple turbines are investigated for a single row arrangement with only two turbines and a two row arrangement containing three turbines. The results demonstrate that the non-hydrostatic solver shows better agreement when validated against published experimental data. Notably, the mesh density at the device location can strongly influence the simulated thrust from the disc. Although the actuator disc model can generally replicate the wake interactions well, the results indicate that it cannot accurately characterize the flow for regions with high turbulences. While a model setup with the largest lateral spacing (1.5D) demonstrates excellent agreement with the experimental data, the 0.5D model (smallest gap) deviates by up to 25%. These findings demonstrate the effectiveness of the applied source term in reproducing the wake profile, which is comparable with the published data, and highlight the inherent nature of the RANS and actuator disc models.
A numerical investigation on the effectiveness of the actuator disc method in producing the interactions of multiple tidal stream devices via the 3D-RANS finite element model Telemac3D is explored. The methodology for the implementation of the source term to represent an array of 20 m rotor diameter turbines deployed in an idealized channel is reviewed and discussed in detail. Flow interactions between multiple turbines are investigated for a single row arrangement with only two turbines and a two row arrangement containing three turbines. The results demonstrate that the non-hydrostatic solver shows better agreement when validated against published experimental data. Notably, the mesh density at the device location can strongly influence the simulated thrust from the disc. Although the actuator disc model can generally replicate the wake interactions well, the results indicate that it cannot accurately characterize the flow for regions with high turbulences. While a model setup with the largest lateral spacing (1.5D) demonstrates excellent agreement with the experimental data, the 0.5D model (smallest gap) deviates by up to 25%. These findings demonstrate the effectiveness of the applied source term in reproducing the wake profile, which is comparable with the published data, and highlight the inherent nature of the RANS and actuator disc models.
2025, 39(3): 518 -528
doi: 10.1007/s13344-025-0039-0
[Abstract](0)
Abstract:
Grouting represents a reliable method for strengthening fractured rock masses and preventing seawater infiltration in subsea tunnel engineering. However, grouting composites are continuously subjected to harsh marine environments, experiencing both chemical and physical effects from high-concentration erosive seawater ions, elevated water pressure, and complex flow fields. This multi-factor erosion deterioration diminishes the waterproofing capabilities of grouting composites and threatens the service life of subsea tunnel linings. To investigate the erosion deteriortion mechanism induced by sulfate, erosion weakening experiments were conducted using a seawater flow simulation device. The research examined the compressive strength and permeability coefficient of grouting composites under different erosion durations, water-cement ratios, and grouting pressures. In the later stages of the experiment, the strength of grouting composites in the static water erosion control group (SEG) and dynamic water erosion group (DEG) decreased by 31.2% and 18.8%, respectively, compared to the freshwater control group (FG). Futhermore, the permeability coefficient exhibited significant increases. Subsequent microscopic analyses of the eroded grouting composites were performed. This research elucidated the erosion-weakening mechanism of grouting composites subjected to sulfate-induced degradation in complex marine environments. The study emphasizes the critical role of erosion resistance and durability in design and implementation. From practical perspective, this work establishes a foundation for developing enhanced strategies to improve the long-term performance and integrity of grouting composites in subsea tunnel applications.
Grouting represents a reliable method for strengthening fractured rock masses and preventing seawater infiltration in subsea tunnel engineering. However, grouting composites are continuously subjected to harsh marine environments, experiencing both chemical and physical effects from high-concentration erosive seawater ions, elevated water pressure, and complex flow fields. This multi-factor erosion deterioration diminishes the waterproofing capabilities of grouting composites and threatens the service life of subsea tunnel linings. To investigate the erosion deteriortion mechanism induced by sulfate, erosion weakening experiments were conducted using a seawater flow simulation device. The research examined the compressive strength and permeability coefficient of grouting composites under different erosion durations, water-cement ratios, and grouting pressures. In the later stages of the experiment, the strength of grouting composites in the static water erosion control group (SEG) and dynamic water erosion group (DEG) decreased by 31.2% and 18.8%, respectively, compared to the freshwater control group (FG). Futhermore, the permeability coefficient exhibited significant increases. Subsequent microscopic analyses of the eroded grouting composites were performed. This research elucidated the erosion-weakening mechanism of grouting composites subjected to sulfate-induced degradation in complex marine environments. The study emphasizes the critical role of erosion resistance and durability in design and implementation. From practical perspective, this work establishes a foundation for developing enhanced strategies to improve the long-term performance and integrity of grouting composites in subsea tunnel applications.
2025, 39(3): 529 -540
doi: 10.1007/s13344-025-0040-7
[Abstract](0)
Abstract:
Under severe sea conditions, wave slamming on ships and marine engineering structures may lead to structural damage and casualties. Moreover, the strong nonlinearity inherent in the wave slamming process significantly limits the accuracy of numerical analyses and finite element simulations. Therefore, this paper takes a new type of floating wind turbine as an example and performs a physical model test on the wave slamming characteristics of this floating wind turbine. Based on a 1:50 model of the PivotBuoy floating wind turbine, an experimental study is performed under the combined effects of wind-wave loads on the peak pressure, duration, and pressure distribution of slamming. First, two sets of mooring systems, the combined scheme and the full mooring chain scheme, are designed to conduct a series of experimental studies of model slamming under different wind and wave incidence angles, wave heights, and wave periods. By doing so, the slamming characteristics of the wind turbine can be obtained. Moreover, to solve the problem of the large pitch motion response of the prototype wind turbine, a set of vertically oscillating structures is designed, and the slamming pressure characteristics of the optimized model are also investigated through model tests.
Under severe sea conditions, wave slamming on ships and marine engineering structures may lead to structural damage and casualties. Moreover, the strong nonlinearity inherent in the wave slamming process significantly limits the accuracy of numerical analyses and finite element simulations. Therefore, this paper takes a new type of floating wind turbine as an example and performs a physical model test on the wave slamming characteristics of this floating wind turbine. Based on a 1:50 model of the PivotBuoy floating wind turbine, an experimental study is performed under the combined effects of wind-wave loads on the peak pressure, duration, and pressure distribution of slamming. First, two sets of mooring systems, the combined scheme and the full mooring chain scheme, are designed to conduct a series of experimental studies of model slamming under different wind and wave incidence angles, wave heights, and wave periods. By doing so, the slamming characteristics of the wind turbine can be obtained. Moreover, to solve the problem of the large pitch motion response of the prototype wind turbine, a set of vertically oscillating structures is designed, and the slamming pressure characteristics of the optimized model are also investigated through model tests.
2025, 39(3): 541 -547
doi: 10.1007/s13344-025-0057-y
[Abstract](0)
Abstract:
Recently, during the investigations on planetary oceans, Hirota-Satsuma-Ito-type models have been developed. In this paper, for a (2+1)-dimensional generalized variable-coefficient Hirota-Satsuma-Ito system describing the fluid dynamics of shallow-water waves in an open ocean, non-characteristic movable singular manifold and symbolic computation enable an oceanic auto-Bäcklund transformation with three sets of the oceanic solitonic solutions. The results rely on the oceanic variable coefficients in that system. Future oceanic observations might detect some nonlinear features predicted in this paper, and relevant oceanographic insights might be expected.
Recently, during the investigations on planetary oceans, Hirota-Satsuma-Ito-type models have been developed. In this paper, for a (2+1)-dimensional generalized variable-coefficient Hirota-Satsuma-Ito system describing the fluid dynamics of shallow-water waves in an open ocean, non-characteristic movable singular manifold and symbolic computation enable an oceanic auto-Bäcklund transformation with three sets of the oceanic solitonic solutions. The results rely on the oceanic variable coefficients in that system. Future oceanic observations might detect some nonlinear features predicted in this paper, and relevant oceanographic insights might be expected.
2025, 39(3): 548 -561
doi: 10.1007/s13344-025-0044-3
[Abstract](0)
Abstract:
Maritime target recognition and image perception enhancement are gradually being promoted and applied in ocean engineering. This paper proposes the attentional multi-pixel fusion (AMF) algorithm for the intelligent navigation of unmanned surface vessels (USVs). The algorithm preprocesses the image pixel matrix in blocks, computes the mapping between regional and full-pixel matrices, and adaptively equalizes the mapping weights via a Gaussian-fuzzy matrix. This approach guarantees the preservation of the target contour and texture information. Compared with five classic enhancement algorithms, the AMF algorithm improves the peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM). Experimental validation via YOLOv8 for maritime target detection demonstrates 2.1% and 2.4% improvements in the evaluation indices over training on 4000 original images, with shorter training times and lower confusion rates. In maritime target ranging, the AMF algorithm, coupled with the ISR method, exhibits the lowest improved stereo ranging mean absolute error and standard deviation values and higher similarity between the regional and full-pixel matrices. In summary, the AMF algorithm excels in target detection and ranging, offering promising applications in ocean engineering, such as marine resource exploitation, path planning, and intelligent collaboration among unmanned vessels.
Maritime target recognition and image perception enhancement are gradually being promoted and applied in ocean engineering. This paper proposes the attentional multi-pixel fusion (AMF) algorithm for the intelligent navigation of unmanned surface vessels (USVs). The algorithm preprocesses the image pixel matrix in blocks, computes the mapping between regional and full-pixel matrices, and adaptively equalizes the mapping weights via a Gaussian-fuzzy matrix. This approach guarantees the preservation of the target contour and texture information. Compared with five classic enhancement algorithms, the AMF algorithm improves the peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM). Experimental validation via YOLOv8 for maritime target detection demonstrates 2.1% and 2.4% improvements in the evaluation indices over training on 4000 original images, with shorter training times and lower confusion rates. In maritime target ranging, the AMF algorithm, coupled with the ISR method, exhibits the lowest improved stereo ranging mean absolute error and standard deviation values and higher similarity between the regional and full-pixel matrices. In summary, the AMF algorithm excels in target detection and ranging, offering promising applications in ocean engineering, such as marine resource exploitation, path planning, and intelligent collaboration among unmanned vessels.
2025, 39(3): 562 -572
doi: 10.1007/s13344-025-0041-6
[Abstract](0)
Abstract:
This study investigates the load-bearing capacity of open-ended pipe piles in sandy soil, with a specific focus on the impact of soil plug constraints at four levels (no plug, 25% plug, 50% plug, and full plug). Leveraging a dataset comprising open-ended pipe piles with varying geometrical and geotechnical properties, this research employs shallow neural network (SNN) and deep neural network (DNN) models to predict plugging conditions for both driven and pressed installation types. This paper underscores the importance of key parameters such as the settlement value, applied load, installation type, and soil configuration (loose, medium, and dense) in accurately predicting pile settlement. These findings offer valuable insights for optimizing pile design and construction in geotechnical engineering, addressing a longstanding challenge in the field. The study demonstrates the potential of the SNN and DNN models in precisely identifying plugging conditions before pile driving, with the SNN achieving R2 values ranging from 0.444 to 0.711 and RMSPE values ranging from 24.621% to 48.663%, whereas the DNN exhibits superior performance, with R2 values ranging from 0.815 to 0.942 and RMSPE values ranging from 4.419% to 10.325%. These results have significant implications for enhancing construction practices and reducing uncertainties associated with pile foundation projects in addition to leveraging artificial intelligence tools to avoid long experimental procedures.
This study investigates the load-bearing capacity of open-ended pipe piles in sandy soil, with a specific focus on the impact of soil plug constraints at four levels (no plug, 25% plug, 50% plug, and full plug). Leveraging a dataset comprising open-ended pipe piles with varying geometrical and geotechnical properties, this research employs shallow neural network (SNN) and deep neural network (DNN) models to predict plugging conditions for both driven and pressed installation types. This paper underscores the importance of key parameters such as the settlement value, applied load, installation type, and soil configuration (loose, medium, and dense) in accurately predicting pile settlement. These findings offer valuable insights for optimizing pile design and construction in geotechnical engineering, addressing a longstanding challenge in the field. The study demonstrates the potential of the SNN and DNN models in precisely identifying plugging conditions before pile driving, with the SNN achieving R2 values ranging from 0.444 to 0.711 and RMSPE values ranging from 24.621% to 48.663%, whereas the DNN exhibits superior performance, with R2 values ranging from 0.815 to 0.942 and RMSPE values ranging from 4.419% to 10.325%. These results have significant implications for enhancing construction practices and reducing uncertainties associated with pile foundation projects in addition to leveraging artificial intelligence tools to avoid long experimental procedures.
Image Enhancement by Improving the Dark Channel Prior Method for Underwater Concrete Crack Detection
2025, 39(3): 573 -584
doi: 10.1007/s13344-025-0061-2
[Abstract](0)
Abstract:
Health monitoring of underwater concrete facility systems is important in civil engineering. Unlike conventional manual inspection techniques, digital image processing offers a more convenient and effective approach, becoming an indispensable tool for structural inspection. Cracks, which are pervasive defects, are a central focus of structural deterioration research. However, the complexity of the marine environment poses challenges to underwater visibility. In this study, the underwater environment under controlled laboratory conditions is replicated, where varying turbidity and illumination conditions and images of concrete cracks are captured. An approach combining a defogging algorithm with guided and fast guided filtering techniques is proposed to enhance both natural underwater images and crack images captured through experimental photography. When applied to turbid crack images captured under two different suspension conditions, the method increases the information entropy (IE) by 32.92% and 17.92% and the underwater color image quality evaluation (UCIQE) by 35.76% and 18.36%, respectively. These results demonstrate its efficiency in enhancing image definition. The findings of this study could significantly impact the practical applications of image visualization and evaluation for underwater concrete cracks.
Health monitoring of underwater concrete facility systems is important in civil engineering. Unlike conventional manual inspection techniques, digital image processing offers a more convenient and effective approach, becoming an indispensable tool for structural inspection. Cracks, which are pervasive defects, are a central focus of structural deterioration research. However, the complexity of the marine environment poses challenges to underwater visibility. In this study, the underwater environment under controlled laboratory conditions is replicated, where varying turbidity and illumination conditions and images of concrete cracks are captured. An approach combining a defogging algorithm with guided and fast guided filtering techniques is proposed to enhance both natural underwater images and crack images captured through experimental photography. When applied to turbid crack images captured under two different suspension conditions, the method increases the information entropy (IE) by 32.92% and 17.92% and the underwater color image quality evaluation (UCIQE) by 35.76% and 18.36%, respectively. These results demonstrate its efficiency in enhancing image definition. The findings of this study could significantly impact the practical applications of image visualization and evaluation for underwater concrete cracks.
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- July 2025
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