bluuebunny/crossref_metadata_2025_split huggingface dataset:
On Methodology for a Digital Twin of Ship Propulsion Under Harsh Environmental Conditions
Authors: Purcell Etienne , Nejad Amir R. , Böhm Angelo , Sapp Lina , Lund Jorrid , von Bock und Polach Franz , Nickerson Brendon M. , Bekker Anriëtte , Gilges Markus , Saleh Ahmed , Lehmann Benjamin , Jacobs Georg , Valavi Mostafa , Kranz Tobias 
Published: August 2024

Abstract
The propulsion system of a ship is a critical element for its safety and integrity. Therefore, it must be maintained properly to ensure that a vessel is able to fulfill its primary purpose. The need for maintenance is even more pronounced in ships where extreme environmental conditions, such as ice-covered waters, are expected. This is due to an increase in the magnitude and uncertainty of loads and therewith the increase in possible damages if the propulsion system fails. The use of digital twins is becoming increasingly popular in shipping and can also be used for intelligent maintenance and operation prediction of the propulsion system. This paper proposes the methodology of creating such a digital twin with a specific focus on the required measurement infrastructure, modeling of components, loads, and damage as well as how all of these aspects are combined. The digital twin was created using a polar supply and research vessel, S.A. Agulhas II. Bearings are discussed from the view of high-fidelity simulations and wear modeling. The propeller is modeled as a point mass with the propeller laws for predicting the hydrodynamic torque and thrust. Shaft dynamics are modeled using either a lumped-mass torsional model, a modal model, or a finite element model. Damage of the shaft and the propeller is based on SN-curve fatigue calculations. The motor torque is modeled using an equivalent circuit model while motor damage is modeled by estimating the hottest temperature within the motor windings. Ice-breaking simulations are used as inputs to propeller-ice interaction models to obtain insight into the loads caused by these interactions. The material properties of ice used during simulations are validated using experiments. The need for further validation for low-fidelity models and the need for reduced order modeling or surrogate models for high-fidelity models are discussed. Finally, the implementation of this digital twin is discussed based on the developed model and the found problems that still need to be overcome to increase the technology readiness level.
Damage Localization on Wind Turbine Blades Using Acoustic Emission (AE) Signals and Graph Neural Network (GNN)
Authors: Zhao Zhimin , Chen Nian-Zhong 
Published: August 2024

Abstract
Accurately localizing the source of early structural damage on wind turbine blades poses a challenge for constructing acoustic emission (AE) based structural health monitoring (SHM) systems. Existing damage localization methods struggle to extract and utilize the intricate connections inherent in the AE signals. A novel method for localizing structural damage zone on wind turbine blades based on AE and graph neural networks (GNN) is proposed in this paper. First, the AE signals are converted into graph structure data in non-Euclidean space combined with time-frequency analysis. Then, the Euclidean distance between the features of each pair of nodes is calculated to determine the connectivity of the graph. The information of the neighboring nodes in the graph is aggregated using the message passing paradigm, which can not only make effective use of the node features, but also excavate the deeper intrinsic connection of the AE signals. The proposed method can easily localize structural damage on wind turbine blades with the assistance of the established graph. Another novelty of the proposed method is its ability to locate damage for wind turbine blade with high accuracy using only one AE sensor. This not only simplifies the sensor setup but also leads to significant cost reduction. The effectiveness of the proposed method is validated using an experimental dataset collected from a segment of a wind turbine blade. The results demonstrate the superior performance and high accuracy of the proposed method.
Experimental Investigation on the Current Suppression Performance of a Plate-Net Complex Mounted Beneath a Floating Breakwater
Authors: Gu Jian , Ni Xinyun , Cheng Yong , Bu Shuxia , Kuang Xiaofeng 
Published: August 2024

Abstract
Suppression of currents is crucial for aquaculture and coastal engineering structures like aquaculture platforms and floating breakwaters. There have been many remarkable studies on current integration in the flow channel, mostly aiming to reduce the turbulence intensity. Meanwhile, the investigation into current suppression is relatively scarce, especially in the case of floating structures. In the present article, a novel plate-net complex is investigated experimentally, mounted beneath a floating breakwater to mitigate the current and wave simultaneously. The dependency of suppression efficiency is investigated on the flow speed, the height ratio of the plate, the solidity ratio of the net, and the motion of the floating breakwater, respectively, through model tests in a recirculating flume. A velocimeter matrix is designed to measure the flow velocity upstream and downstream of the floating breakwater simultaneously. According to the analysis, the dependency of the average current reduction ratio is found on the current speed of incoming flow, height ratio, solidity ratio and the motion of the floating breakwater. Meanwhile, the significance of the solidity ratio of the net is less than that of the height ratio of the plate on the suppression efficiency. The experimental results demonstrate the effectiveness of the plate-net complex in current suppression and provide significant references for the design and optimization of the floating breakwater.
Study on Weather Vane Effect of a Single-Point Mooring Floating Offshore Wind Turbine
Authors: Chen Jiahao , Gao Yifan , Wang Kai 
Published: August 2024

Abstract
Affected by extreme loads, structural fatigue and other factors in marine environment, yaw system failures of offshore wind turbines are frequent, making floating wind turbines operation and maintenance costs high. Regarding this issue, it is an effective solution to combine single-point mooring system with floating offshore wind turbines. However, dynamic response characteristics of a single-point mooring floating offshore wind turbine (SPM-FOWT), especially the weather vane effect under misaligned wind, wave and current coexisting condition, are still unknown. In this paper, a high-precision downwind type SPM-FOWT simulation model is constructed by the in-house aero-hydro-elastic-servo coupling software for floating offshore wind turbines, and the contributions from wind, wave, and current loads on the wind tracking performance of a SPM-FOWT are also investigated. It is found that the angle to the wind of the SPM-FOWT is usually biased, which is affected by the comprehensive influence of wind, wave and current direction. In addition, It is found that the horizontal arrangement position of the single-point mooring turret has a significant effect on the weather vane effect of a SPM-FOWT.
Reliability Analysis of Ro-Ro Vessel Movable Vehicle Ramps Under Vehicle Moving Load
Authors: Tao Shuo , Zhu Ling , Liang Qiyu , Zhang Qiying 
Published: August 2024

Abstract
In the design of roll-on/roll-off ship structures, movable vehicle ramps serve as a bridge connecting different decks and are typically subjected to various moving vehicles. However, the loads carried by the ramp during its operation often vary from the design loads considered in the design phase. Due to the uncertainty of vehicle loads and the structural materials, it is of significant importance to assess the reliability of the movable vehicle ramp structure. To investigate the structural reliability of the movable vehicle ramp structure under vehicle moving loads, the weight of the vehicle, the moving speed, and the thickness of the top plate of the ramp were selected as random variables. Based on numerical results, the limit state equation of the movable vehicle ramp structure was obtained by the Box-Behnken design response surface method. Then, the structural reliability index was calculated by the checking point (JC) method, and the influence of each variable on the structural reliability of the movable ramp was derived through sensitivity analysis. Finally, the structural optimization of the plate thickness was carried out according to the reliability analysis, which is significance guidance for the optimization of the movable ramp design.
Effect of Seawater Immersion on the Steel Plate Reinforced With Fiber-Reinforced Composites
Authors: Matsuo Tsuyoshi , Sakurai Akio , Yanagimoto Fuminori , Ishibashi Kinya 
Published: August 2024

Abstract
In case of onshore structures such as bridges and elevated roads, repairs and reinforcements by carbon fiber reinforced plastics (CFRPs) have been in practical use for the damaged or deteriorated parts. However, in the other case of maritime structures, ship hulls and offshore structures are operated under conditions exposed to salt water and repeated cycles of drying and wetting, which is an even more severe corrosive environment than onshore structures. Furthermore, during repairs and constructions, it is necessary to suspend operation and usage, and it is undesirable to take a long time in the environment such as waves and wind. Therefore, it is necessary to minimize and simplify the working time required for repairs as much as possible.
CFRP strand sheets are reinforcement materials made by processing carbon fiber strands impregnated with resin into a blind-like shape, and they excel in workability as the impregnation of adhesive resin is fast during the adhesive construction to steel materials. If this repair and reinforcement method using CFRP strand sheets can be applied to ship hulls and marine structures, rapid repairs by manpower or operating machine are possible, leading to improved operational efficiency.
In this study, the degree of corrosive degradation caused by seawater immersion when CFRP strand sheets are used as reinforcements is verified experimentally, and the applicability of CFRP repair and reinforcement to ship hulls and offshore structures is investigated.
Study on Wave Scattering by Inverse T-Type Bottom-Standing Breakwater
Authors: Sharma Priya , De Soumen , Gayen Rupanwita 
Published: August 2024

Abstract
In the present study, the scattering of normal incident wave by (i) single and (ii) dual inverse T-type bottom standing breakwaters are analyzed under the assumption of linearized water wave theory. The objective of the current study is to compare the effectiveness of the two breakwater configurations and to provide some useful results for engineering design and application. To address the physical problem, we employ Havelock’s expansion methodology and Galerkin’s approximation technique. We utilize multi-term Galerkin approximations that incorporate ultraspherical Gegenbauer polynomial to solve the integral equations that arises in the mathematical analysis. This study demonstrates how to encounter the singularity by using ultra-spherical Gegenbauer polynomial as basis function with suitable weight. To understand how the profile geometry can affect the performance of the bottom standing inverse T-type breakwater’s main dimensions, including its profile height and width, is conducted on several hydrodynamic quantities of interests such as reflection, transmission coefficient and horizontal drift force. The numerical estimates are first validated against the data of existing studies in the literature, computed and graphically discussed for a variety of structural conditions, including the height and width of breakwater submergence. The effectiveness of both single and dual breakwaters can be assessed by examining wave reflection and horizontal drift forces, as evident in the graphical representations. This theoretical framework not only offers a promising method for addressing wave interaction with bottom-standing in-verse T-type breakwater model but also serves as a dependable reference point for complex numerical solutions of integral equations.
Assessment of the Group Behavior of Torpedo Anchors Through Finite Element Modelling
Authors: Kronemberger Lopes Guilherme , Mendes de Sousa José Renato , Carre de Oliveira Allan , Guerreiro Basilio Costa Genzani Rachel 
Published: August 2024

Abstract
In Brazilian offshore fields, torpedo anchors are extensively used in deep-water mooring systems. These anchors are known to be cost-effective and capable of withstanding high vertical loads. Despite their successful usage in the offshore industry, the increasing loads imposed by the mooring systems in ultra-deepwater applications demand higher anchor holding capacities. In this scenario, a possible solution is to consider a group of torpedo anchors, which has not been investigated. Hence, this article uses a three-dimensional nonlinear finite element model to present a numerical study on the group behavior of typical torpedo anchors embedded in a purely cohesive isotropic soil. In this model, the soil is simulated with solid elements representing its nonlinear behavior and the large deformations involved. The torpedo anchors are also modeled in detail with solid elements.
Moreover, the anchor-soil interaction is addressed with contact finite elements that allow relative sliding with friction between the surfaces in contact. Several analyses are conducted to understand the response of this type of anchor when installed in groups. The research addresses some essential features in group analysis, such as anchor spacing, connection between the anchors, and soil-structure interaction. Additionally, the results are compared with those from a single anchor installed in the same conditions to highlight the torpedo anchor group efficiency.
Development and Validation of Real-Time Hybrid Model Testing Framework for Aerodynamic Simulation of Floating Wind Turbines
Authors: Yao Tiancheng , Cai Weikai , Wang Yipin , Zhao Yongsheng , Wang Jin 
Published: August 2024

Abstract
Globally, there is a surge in offshore wind farms, with Floating Offshore Wind Turbines (FOWTs) becoming the focal point of research and industry investment. To ensure the accuracy of the numerical model and the operation safety of FOWTs, it is crucial to conduct model test. This will provide a comprehensive understanding of the complex structural behavior of FOWTs under the combined influence of wind and wave loads. However, the process is complicated due to Reynolds-Froude scaling incompatibilities. The reproduction of aerodynamic loads of FOWTs in wave basin model tests is complex because the aerodynamic loads are dominated by Reynolds similarity. To address this issue, various strategies have been employed, including the use of a tuned actuator disk or a redesigned rotor to achieve the correct scaled thrust at low Reynolds numbers. However, these methods only ensure the similarity of mean thrust under some certain wind velocities, while some important properties of floating wind turbine are still out of reach, such as aerodynamic damping and wind turbine control strategy. In this paper, a Real-Time Hybrid Testing (RTHT) framework is introduced to integrate aerodynamic thrust during wave basin model tests. The feasibility and fidelity of the proposed RTHT framework are verified by using a Pitch-mode Modeling System (PMMS) of FOWT so that the construction and commission of RTHT framework could be conducted on land and modified. The PMMS can accurately simulate the aerodynamic load, inertial load, and hydrostatic restoring moment of a FOWT. Additionally, the RTHT system is calibrated and enhanced by examine the correlation between experimental measurements and simulation results. The results indicate that the proposed RTHT framework, based on PMMS, can effectively reproduces the aerodynamic load of FOWT under different wind conditions and control regimes in a low latency.
Evaluation of Motion-Vibration Couples for Semi-Submersible Offshore Floating Wind Turbines
Authors: Xu Kai , Liu Qiang , Zhao Zhixin , Liu Fushun 
Published: August 2024

Abstract
The structural reliability design of floating offshore wind turbines (FOWT) relies on the analyzable and integrated coupled dynamics mechanisms. As the FOWT consisting of complex rigid-flexible coupled substructures is subjected to severe wind, wave and current loads, both accurate and quantitative evaluations of the coupled dynamic performance are challenging. Taking into account these factors, the model of the aero-hydro-servo-elastic FOWT system including a tower with a torsional degree-of-freedom (DOF) has been developed to quantitatively analyze the coupled dynamics. As the Kane method has the ability to efficiently analyze the performances of complex rigid-flexible systems, it has been implemented in the established model. To evaluate the motion-vibration effect of such model, the comparison responses between the rigid and rigid-flexible FOWT structures have been investigated. Results have shown that the sway response of the rigid-flexible FOWT, also called the motion-vibration coupled model, has been reduced by 12.63% as compared with that of the fully rigid FOWT under the steady state wind of 5 m/s and wave height of 1.2 m. Moreover, the discrepancy of the coupled responses for the heave and yaw calculated between two models has almost varied linearly with the environmental loads. Summarily, the present work provides analytical formations for the accurate modeling and quantitative evaluation of coupling effects for the FOWTs subject to harsh marine environments.
Application of Idealized Structural Unit Method to Determine the Ultimate Strength of Ship Model in Bending
Authors: Lindemann Thomas , La Ferlita Alessandro , Kaeding Patrick 
Published: August 2024

Abstract
The Idealized Structural Unit Method (ISUM) is applied to perform progressive collapse analyses for a 1/3-scaled frigate model in bending. For the load case of pure vertical bending (sagging), the ISUM results are validated against experimental data. The ISUM model is explained in detail taking into account the initial imperfections of stiffeners and the attached plating. In particular, the effect of welding residual stresses on the ultimate hull girder strength is discussed. Displacement controlled nonlinear analyses are performed by using the full Newton-Raphson scheme an incremental iterative solution approach. Furthermore, Smith’s method is applied to determine the progressive collapse behavior the 1/3-scaled frigate model in bending. Smith’s method based calculations are performed under consideration of scantlings and rule based load-end shortening curves of all structural components. Both simplified approaches are applied to determine the progressive collapse behavior of the frigate model in vertical, horizontal and biaxial bending. For the ISUM model the effect of welding residual stress on the ultimate hull girder strength is also proposed for the different load cases.
Effect of Axial Density Distribution in Liquid–Solid Flow in Pipes on the Jumper for Deep Sea Mining
Authors: Takano Satoru , Yamamoto Marcio , Masanobu Sotaro 
Published: August 2024

Abstract
Subsea minerals have been found in the deep water within Japan’s exclusive economic zone. However, the development of subsea minerals has not reached the commercialization stage because many technical issues still need to be addressed.
When slurry pumps are used for lifting seafloor massive sulfides, internal flow in pipes becomes liquid-solid flow. The slurry pump is connected to seafloor production tools by a jumper so that the seafloor production tools can move to collect subsea minerals. To operate the production system safely, simulating the behavior of the jumper is necessary. There is axial density distribution in internal flows in the jumper because of the slip velocity between liquid velocity and solid velocity, and simulating the behavior of the jumper with consideration of density distribution is essential. Thus, we simulated the behavior of the jumper with consideration of density distribution by lumped mass model. We calculated the density distribution at each delivered concentration by equations of hindered settling velocity of solid particles and mixture velocity. The calculated results were compared with experimental results to validate the lumped mass model. The experimental apparatus had a flexible hose of 38 mm in internal diameter, and we used alumina beads of 4 mm in diameter. The comparison showed the behavior by considering density distribution and that with the homogeneous flow which has the uniform density of internal flows. Their comparison showed that the calculated results considering density distribution were more consistent with experimental results than those with the homogeneous flow. In calculating the behavior of the jumper with liquid-solid internal flow, it was important to consider the density distribution.
Prediction of Global Whipping Responses on a Large Cruise Ship Under Unknown Sea States Using an LSTM Based Encoder-Decoder Model
Authors: Liu Ruixiang , Li Hui , Ong Muk Chen , Zou Jian 
Published: August 2024

Abstract
Global whipping responses, characterized by high-frequency vibration components on the hull girder, are typically induced by stern and bow slamming loads. These responses contribute to an increase in vertical bending moments, making their accurate prediction crucial for ship safety. In this study, we build upon our prior work to establish an encoder-decoder model based on Long Short-Term Memory (LSTM), designed to predict whipping responses under varying sea states. The model is trained on a comprehensive dataset, which includes motion data and vertical bending moment history of a large cruise ship under various sea states. This dataset is established via numerical simulation, ensuring a wide range of scenarios for the model to learn from. The efficacy of the LSTM encoder-decoder model in capturing global whipping responses is initially verified under a single sea state case. This step confirms the model’s ability to accurately predict vertical bending moments under known conditions. Subsequently, the model’s performance under unknown sea states is examined. Given that the distribution of training data significantly influences the model’s performance under unknown sea states, a data mixing strategy is employed during the training process in this scenario. The results indicate that the LSTM encoder-decoder model effectively captures whipping responses. Furthermore, the data mixing strategy significantly improves prediction accuracy under unknown sea states, demonstrating the potential of this approach in enhancing ship safety.
Analysis of the Linear Hydroelastic Response of Flexible Floating Solar Devices
Authors: Douteau Louis , Castillo Florian , Gupta Salabh , Ikhennicheu Maria , Gilloteaux Jean-Christophe 
Published: August 2024

Abstract
This paper introduces a numerical model based on generalized modes and linear deflection modes superposition dedicated to the simulation of the dynamic behavior of flexible floating solar concepts. Deflection modes, derived from a Finite Element Method solver, are used as inputs for a linear potential flow solver, enabling the calculation of diffraction and radiation coefficients. These coefficients are then incorporated into a time-domain model, considering deflection modes as additional degrees of freedom.. Verification work considering a generic flexible barge sourced from the literature shows satisfactory results. An application to the simulation of a flexible FPV platform demonstrates a robust estimation of dynamic motions and deflections within the platform.