bluuebunny/crossref_metadata_2025_split huggingface dataset:
Digital Twin for Floating Offshore Wind Foundations Operation and Maintenance Management
Authors: Halme Jari , Souza Ramos Ieza , Mikkola Eeva 
Published: August 2024

Abstract
In the offshore industry, environmental conditions typically have a significant effect on operation performance, maintenance, and total costs.
In this study, predictive maintenance tools were developed in the context of a floating testbed structure (FTB), a cylindrical buoy with features representative of the maintenance needs of floating offshore wind foundations. The FTB was measured dynamically and statistically over the local weather conditions at a harbor in Portugal. A digital twin of the FTB was constructed using the data to assess mooring line loads and hydrodynamic responses at a different place in the Atlantic Ocean.
One major factor restricting operation and maintenance is exposure to dynamic motion. A limiting criterion was demonstrated for heavy manual work based on short-length moving root-mean-square (RMS) values of vibration, acceleration, and roll/pitch. For operational state, history, and statistical analysis, RMS values were profiled as to time-at-level to evaluate the probability of a maintenance weather window and the suitability for maintenance deployment.
FTB digital twin data was used to analyze mooring line loading and remaining useful life (RUL) to provide deterministic decision-making support for justified inspections and structural health monitoring (SHM) under different marine sea state conditions. The approaches shown can also be used for flagging sea-state conditions that are leading to premature failures and reduced lifetime.
Examination of an Analytical Approach for Load-Displacement Behavior of Drag Embedment Anchors and Their Geometrical Optimization
Authors: Dao Duy Anh , Grabe Jürgen , Chmelnizkij Alexander 
Published: August 2024

Abstract
Floating offshore renewables require anchorage to the seabed, often applying drag embedment anchors (DEAs). Industry standards use analytical solutions for evaluating DEA holding capacity and displacement behavior, but their complexity causes challenges in interpretation. This research provides a parametric and graphical analysis of a key analytical solution used internationally to predict the load-displacement behavior of DEAs in clay. It aims to clarify this solution’s calculations and identify optimal DEA geometry. Optimal shaft and fluke lengths for a simplified DEA are determined based on weight and cost-effectiveness (minimum volume) and safety (maximum bearing capacity and penetration depth). A solution set is presented, showing various optimal solutions tailored to predefined objectives. Comparative examination of ten DEA configurations reveals that no single design is universally optimal. Instead, strategic balancing of objectives, such as operational efficiency, cost-effectiveness, and safety margins, is essential. This approach underscores the need for a holistic view in DEA design, accommodating diverse objectives to achieve effective anchorage solutions. In conclusion, the study validates the applicability of established analytical solutions in predicting DEA behavior and in determining optimal geometries. These insights are crucial for economic efficiency and safety, offering guidance for future sustainable and reliable offshore infrastructure design.
Experimental Study of Deflector on Scour Reduction Around Artificial Reef
Authors: Liu Xianyi , Wang Xinxin , Zhao Fenfang , Tang Yanli 
Published: August 2024

Abstract
Artificial reefs play a vital role in marine ecosystem restoration, yet their effectiveness is compromised by local scouring, leading to settlement and burial. This study focuses on mitigating scouring around a cubic artificial reef (CAR) (100mm × 100 mm × 100 mm) through the strategic installation of deflectors. A series of 17 local scour model experiments were conducted by varying deflector shapes (flat plate, curved plate), quantities (1, 4 (full-enclosed)), deflector angles of attack (30°, 45°, 60°), and deflector heights (3 mm, 0 mm, −10 mm, −20 mm) from the sand bed. The experiments were carried out in a 15000 mm × 400 mm × 500 mm scour flume, and were scaled per Froude’s criterion (λ = 1:20), with an average velocity u0 = 0.246 m/s and clear water scour conditions. The main findings include: (1) The angle of attack significantly influences the extent of scour holes upstream of the artificial reef with a single-sided deflector, with minimum scour observed at 60°; (2) Deflector height significantly impacts the distribution of scour holes, with the −10 mm height inducing more serious downstream accumulation and larger upstream scour hole range than those with 3 mm and 0 mm height; (3) Full-enclosed deflectors demonstrate superior scour prevention, which decrease the maximum scour depth by 28.0%. So it provides an essential support to prevent reef overturning. In terms of scour topography, sand beds on both sides of reefs with full-enclosed deflectors exhibit pile-up, contrasting with minimal accumulation around reefs with single deflectors. Finally, the range analysis results show that the deflector shape has a more significant impact on the maximum scour depth and length of the scour hole compared to the installation height of the deflector. Our research explores the use of a flow-altering method as a scour countermeasure for the CAR, demonstrating that a specially designed deflector can effectively reduce local scour.
Numerical Investigation on Hydroelastic Response of a Model Ship in Regular Head Waves
Authors: Zhang Han-Wen , Zhu Ling , Liang Qi-Yu , Dai Shao-ling 
Published: August 2024

Abstract
With the increasing size of ships, their flexibility plays a more and more important role in ship motion predictions. However, existing numerical prediction of ship motion in regular waves usually does not consider the elastic response of the ship, which often regards the ship as a rigid body. Therefore, hydroelastic effects on ship motion need to be taken into account in the research. With the continuous progress of advanced research, many studies on ship hydroelastic response have emerged, but most of them still stay in the hydroelasticity theories based on potential flow theory or the one-way coupling numerical simulation based on RANS/CFD and FEM. To strengthen the interaction between fluid and structure, this paper uses the two-way coupling between fluid solver Star-CCM+ and finite element software Abaqus to calculate the vertical motion RAOs of a model ship at different measuring points in regular head waves. The two-way coupling method exchanges real-time data of pressure and nodal displacements between the fluid domain in Star-CCM+ and the three-dimensional structural model in Abaqus, and uses the mesh morphing method to simulate the motion of the ship. The computational results are compared with the solution of the rigid body calculated by Star-CCM+, the results predicted by fluid solver ANSYS-AQWA based on three-dimensional potential flow theory and model test results, which verifies the feasibility of the two-way coupling method.
Design and Optimization of Layout and Dimensions of the M4 Wave Energy Converter System Under Regular and Irregular Waves
Authors: Wang Wei , Xie Yonghe , Zhang Jiping , Li Gangqiang 
Published: August 2024

Abstract
In this paper, we discuss the dimension optimization of a single floater and the layout and geometry optimization of the M4 wave energy converter system. The M4 system has a single bow float and one or more middle floats in a rigid connection. The stern float is connected to the center floats by a transom, and the hinge above the center floats carries a damper for power conversion. For the calculation of the hydrodynamic coefficients, the FHLAN hydrodynamic coefficient solver is used to calculate the single-floater hydrodynamics, and the commercial software WADAM is used to calculate the coefficients of the hydrodynamics of the multi-floater hydrodynamics. In this paper, with a given configuration (the number of floaters is constant), a constrained optimization problem is well established. An optimal distance between each floater and the optimal geometric shape will be obtained by running a simulation. In this paper, the single floating body and the M4 system are studied, and the optimum dimensions of the single floating body and the optimum layout and geometry of the M4 system are given for regular and irregular waves.
Vibroacoustic Performance of a Stiffened Plate With Perforation Under the Excitation of Turbulent Boundary Layer
Authors: Li Piao , Li Yukun , Zhang Jingyu , Chen Meixia , Wang Ting 
Published: August 2024

Abstract
Perforated plate is an essential part of underwater vehicles. Investigation on its sound and vibration characteristics has significant influences on the performance of the underwater vehicles. Premised on the fluid-solid interaction, this article presents the vibroacoustic performance of a stiffened plate with perforation under the excitation of turbulent boundary layer (TBL) with the finite element approach. The TBL excitation in the form of dynamic pressure is calculated by using the CFD technique. By analyzing the properties of the excitation at different location versus frequency, the intrinsic frequency and mode shapes, and vibration and sound radiation of the stiffened perforated plate, it is found that the dynamic pressure attenuates dramatically along with the frequency, multiple natural modes of the stiffened perforated plates are evoked which radiates sound to the adjacent fluids. Due to the strong stiffeners, there are several vibration modes which strongly radiate sound within the areas among the stiffeners. The mechanism of the radiation peaks is stated that the radiation efficiency of a surface vibration mode is much higher than that of a dipole and quadrupole vibration mode. This work provides guidance for the optimization and implementation for the stiffened perforated plate in underwater vehicles.
Colorimetric Determination of Amine-Based Shale Inhibitors in Water-Based Drilling Fluids
Authors: Wagle Vikrant , Pal Omprakash , Al-Yami Abdullah , Safran Ali , Pino Rafael , Olivares Tulio 
Published: August 2024

Abstract
Formations that contain hydratable shale or mixed layers of reactive clay can lead to wellbore instability issues during drilling operations. Shale inhibitors are used to limit the interaction of water with clay particles. Amine-based compounds are commonly used shale inhibitors in water-based drilling fluids. Amine-based shale inhibitors are typically added in predetermined concentrations in water-based drilling fluids. The shale inhibitors prevent the swelling and disintegration of shales, preventing problems during the drilling process, such as wellbore instability, viscosity build-up, high torque and drag, bit balling and stuck pipe, and wellbore caving. During the drilling process, the shale inhibitors are either consumed or may be lost to the formation. Accordingly, there exists a need for quantifying and tracking active concentrations of amine-based shale inhibitors in drilling fluids in real-time conditions.
The paper describes a method for quantifying and tracking an amine-based shale inhibitor in a drilling fluid through UV-visible spectrophotometry. The method involves reacting the amine-based shale inhibitor with a complexing agent and then measuring the absorption intensity of the residual complexing agent solution using a portable UV-visible spectrophotometer. For varying concentrations of an amine-based shale inhibitor, a correlation between a concentration of the amine-based shale inhibitor in a water-based drilling fluid and an ultraviolet (UV)-visible absorption intensity is determined. A calibration plot is generated from the correlations. Samples of a circulating drilling fluid having unknown concentrations of amine-based shale inhibitor are collected. The concentrations of amine-based shale inhibitor in the samples of the circulating drilling fluid are estimated using the calibration plot.
The method of colorimetric determination of amine-based shale inhibitors in water-based drilling fluids was field validated successfully. The method was successful in tracking the depletion rates and any addition of the amine-based shale inhibition in the water-based drilling fluids during drilling.
Fatigue Analysis of a Diffuser-Augmented Fiber-Composite Tidal Turbine
Authors: Rotor Mark Anthony , Genita Jeff David , Nacario Jericho Lance 
Published: August 2024

Abstract
This study investigates the structural performance of the diffuser-augmented horizontal axis tidal turbine (DATT) by examining the fatigue performance of its blades on different hydrofoil diffuser design parameters. While the diffuser augmentation relieves the issue of requiring a larger turbine to produce the same amount of power, it also increases the structural load on the turbine blades due to increased power performance. Currently, there is little literature on the structural response to increased load in DATT systems. Hence, this study examines the diffuser hydrofoil design parameters, namely, camber and orientation angle, for the fatigue performance of the turbine blades. In the first phase, the Finite Element (FE) model is created and verified, and the spectrum load cases are generated to simulate dynamic loading. Secondly, the FE model undergoes a static test, and various load spectra are applied for fatigue analysis. Glass Fiber Reinforced Polymer (GFRP) and Carbon Fiber Reinforced Polymer (CFRP) composite materials show satisfactory fatigue performance. Lastly, the third phase determines the level of sensitivity of the angle diffuser and camber to the fatigue performance, wherein the former results in a Sobol index of around 0.95, indicating a high significance level, while the latter parameter results in around 0.05, indicating non-significance. This study concludes that using fiber-reinforced polymer materials is satisfactory in tidal fatigue load application. The understanding of the fatigue behavior of DATT enables the development of better designs and saves on the cost of prototype development. Future work on more design parameters is recommended for optimization and sensitivity studies investigation.
Characterization and Performance Evaluation of Various Types of Polymers Based Latexes for Water Based Drilling Fluids Applications
Authors: Al-Yami Abdullah , Khan Majad , Tahir Muhammed Nawaz , Almulhim Sara , Alsafran Ali , Wagle Vikrant 
Published: August 2024

Abstract
Polymer based latex chemicals are primarily used as fluid loss additive in drilling fluids. They are used to prepare a thin filter cake on the wellbore formation and reduce filtrate loss into the formation. A thin filter cake reduces or eliminates incidences of differential stuck drill pipes.
The objective of this study is to look into two different polymer latexes for the use of water-based drilling fluids applications. The first polymer is based on Styrene-butadiene latex. The second polymer is based on Polyvinyl Acetate emulsion, (PVA).
Analytical techniques such as nuclear magnetic resonance (NMR) spectroscopy, Fourier transform infrared analysis (FTIR), differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA) were used to help in elucidating the structures and physical properties of different latexes. Tests such as for density, rheology, HT/HP filtration and thermal stability were conducted to compare the performance of different latexes in drilling fluid formulations.
Intensive analytical and performance evaluation were done on different types of latexes to find proper way of latex optimization for application for water-based drillings fluids. Styrene butadiene polymer latex outperforms several polymers due to the strong anionic interaction with formation compared to other mechanisms.
Tank Test of Flexible Acrylic Ship Model in Waves for Extreme Response Prediction
Authors: Komoriyama Yusuke , Houtani Hidetaka , Takami Tomoki , Matsui Sadaoki , Fujimoto Wataru 
Published: August 2024

Abstract
In this study, the Most Probable Wave Episodes (MPWEs) for given target Vertical Bending Moments (VBMs) are estimated considering the nonlinearities in the wave and VBM, and the tank tests using a flexible acrylic ship model in the MPWEs are carried out to discuss the effect of body nonlinearity in VBMs on the MPWEs. Although whipping was not considered in this study, this is the first study on MPWEs that considers the body nonlinearity in VBMs in addition to wave nonlinearity. The nonlinearity in waves is considered by using the Higher Order Spectral Method (HOSM), while the body nonlinearity including slamming forces in the VBM is considered by a simplified model incorporating nonlinear correction factors together with the transfer function (TF) of VBM. The MPWEs are estimated by using the HOSM and First Order Reliability Method (FORM), in combination with the simplified VBM model. The VBM nonlinear effects on the HOSM+FORM results are discussed by using the tank test results in MPWEs.
Modified Passive Nonlinear Observer for Multiple Full-Actuated Ships Cooperative Towing
Authors: Li Ze , Wang Lei , Wang Yiting 
Published: August 2024

Abstract
Multi-ship cooperative towing mission is one of the application scenarios of dynamic positioning ships. Dynamic positioning ship can achieve high-precision towing and improve the safety of towing mission. And the observer provides filtered low-frequency motion data for the dynamic positioning system during towing. Passive nonlinear observer is one of widely-used observers in dynamic positioning system. However, the first-order Markov process in passive nonlinear observer cannot accurately describe the interaction forces between ships when it comes to multi-ship cooperative towing mission. This paper discusses the variation character of positioning errors after implementing the estimated value of interaction force into the observer in numerical simulation. The influence of different estimation models and estimation accuracy on positioning errors is considered. By comparing the positioning errors of the adjusted passive nonlinear observer with passive nonlinear observer and alpha-beta observer, the results show that the adjusted passive nonlinear observer helps the dynamic positioning ship to reach a steady state faster than passive nonlinear observer and has a certain improvement in positioning accuracy, and the adjusted passive nonlinear observer can also select the appropriate parameters faster than alpha-beta observer. In conclusion, this paper gives concluding remarks when using passive nonlinear observer in multi-ship cooperative towing mission.
Comparative Study of Different Reduced Order Methods for Fluid-Structure Interaction and Validation With Experimental Results for a LNG Carrier
Authors: Chhoeung Sovanna , Fallet Cedric , Hartmann Moritz , Desmars Nicolas , Klein Marco 
Published: August 2024

Abstract
Ships and offshore structures are constantly exposed to wave loads during their lifetime. The detailed knowledge of their hydrodynamic properties is necessary to ensure the safety of the crew, structure and loading during operation. Therefore, wave loads are crucial to consider in the structural and seakeeping analysis of marine structures during their design process. The assessment of the hydrodynamic behaviour is obtained by numerical simulations accompanied by model tests for validation purposes. Reduced-order methods based on potential flow theory are mostly applied due to its computational efficiency. The aim of this study is to provide an overview on different established reduced order models discussing the theoretical foundation as well as limitations and applications. For this purpose, the sea-keeping behaviour of a LNG carrier is adressed as an application example in this study. The response amplitude operator (RAO) of the LNG carrier is determined with three different established numerical programs and validated by experimental results.
Study on the Vibration of a Cylindrical Shell Structure Using Energy Variational Principle
Authors: Han Xinyi , Li Tianyun , Zhu Xiang , Zhang Cheng , Peng Kehui 
Published: August 2024

Abstract
Numerous investigations have focused on the vibration of cylindrical shells, and achieved fruitful research outcomes [1,2]. However, most of these studies have primarily addressed general boundary conditions, leaving a gap in the analysis of the vibration characteristics of cylindrical shells under complex boundary conditions, which are prevalent in practical applications. Hence, it is necessary to delve into the vibration characteristics of cylindrical shells under various complex boundaries.
This research derives a solution model for cylindrical shells under both general and complex boundary conditions, utilizing the Energy Variational Principle and LOVE Thin Shell Theory. Through this approach, the free and forced vibration characteristics of cylindrical shells have been analyzed. Furthermore, numerical data obtained from the theoretical solution are compared with Finite Element Method (FEM) results to verify the reliability of the proposed method. Additionally, the study investigates the influences of different boundary conditions on the vibration characteristics of the structure.
Acoustic Radiation Study of Wind-Induced Aerodynamic Noise From a Large Cruise Ship Chimney Based on the CAS-RTM Method
Authors: Feng Xiliang , Zhu Yue , Chen Ziheng , Wu Haolong , Liu Ziyang , Gan Jin 
Published: August 2024

Abstract
The cruise ship’s chimney, situated at the highest position of the top deck, is susceptible to aerodynamic noise induced by the sea’s wind field, thus affecting the comfort of passengers on the open deck. This study conducted real measurements on wind-induced aerodynamic noise from a large cruise ship chimney. Based on offshore wind conditions, CFD simulations were conducted to derive the surface pulsation pressure, which in turn was input to the acoustic boundary elements and translated into a compact sound source. Then, employing the Compact Acoustic Source combined with the Ray Tracing Method (CAS-RTM), the acoustic radiation impact of the aerodynamic sound source on the open deck was predicted and analyzed. The predicted outcomes were validated through comparison with measured results, and finally, the aerodynamic shapes of the chimney were optimized. The results highlighted the effectiveness of the CAS-RTM method in obtaining a directional aerodynamic noise source and realizing sound propagation in an open acoustic environment. The directivity of the aerodynamic noise source primarily manifests on the left and right sides of the chimney, with radiated sound pressure exhibiting an increase and then decrease with rising frequency, peaking at 315 Hz. Both aerodynamic optimization schemes enhanced flow separation and vortex shedding while mitigating pulsation pressure distribution. Optimization I demonstrated the largest reduction of 3.172 dB, mainly at position 1 on the front side of the chimney. Conversely, Optimization II exhibited the greatest reduction, measuring 4.414 dB, at position 6 on the rear side of the chimney. This study can provide some instructive insights for the prediction and control of aerodynamic noise from cruise ship chimneys.