bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bucking Reliability Assessment of Offshore Fluid Tanks Subjected to External Pressure With Active Learning Kriging Approaches
Authors: Ren Chao , Eriksen Frank , Gundersen Stian , Xing Yihan 
Published: August 2024

Abstract
Offshore fluid tanks are critical components of offshore oil and gas infrastructure and are often subjected to external pressures that may lead to catastrophic buckling failure. Reliable assessment of their structural integrity is paramount to ensure offshore operations’ safety and environmental sustainability. Traditionally, reliability assessment relies on deterministic methods or experienced formulas, which may not accurately capture uncertainties from the structural and environmental parameters. Furthermore, classical probabilistic methods for reliability assessment also have their limitations. Approximation approaches like the first-order reliability method (FORM) rely on the linearity of the problems. Sampling-based approaches for the reliability assessment, e.g., Monte Carlo simulation (MCS), require many simulations/experiments, which is unrealistic for the real engineer design and optimization process. To address this problem, this study leverages advanced machine learning techniques, named active learning reliability methods, for buckling reliability assessments of offshore fluid tanks under external pressure. One Automatic Tank Cleaning (ATC) container machine from Dynamic Well Solutions AS company is used for the reliability assessment case study. The linear buckling analysis of the ATC tank is performed using finite element methods. The uncertainties encompassing geometric characteristics, material properties, and external loads are considered for the reliability assessment. One typical active learning reliability approach, AK-MCS with U learning function, is applied to estimate the probability of failure considering different minimum buckling factor requirements. The results demonstrate that the active learning reliability approach can significantly reduce the computational cost for the buckling reliability assessment. It enables an accurate and probabilistic assessment of the buckling reliability. Applying active learning reliability techniques could facilitate structural design optimization considering uncertainties.
Hydrodynamic Analysis of Different Configurations of the M4 Wave Energy Converter System Using OREGEN
Authors: Li Gangqiang , Stansby Peter 
Published: August 2024

Abstract
In this paper, the developed frequency domain hydrodynamic response prediction program OREGEN-BEM based on the boundary element method (BEM) with the OpenMP algorithm is applied to analyze the dynamic response of various M4 wave energy converter (WEC) systems with kinematic and mechanical constraints. The algebraic equations corresponding to the clamped connection between body-to-body due to the rigid beam and revolution joint connections are analytically derived, and they are coupled with the system equation through the Lagrange multiplier method. In this paper, a validation study for an array arranged in a triangle shape is conducted to compare the numerical results against the commercial software OrcaWave. The comparison results demonstrate that the results obtained by OREGEN-BEM are accurate and reliable. Then, the developed program is applied to study the dynamic response of the M4 WEC system with different configurations, such as 1-1-1, 1-2-1, 1-2-2, and 1-3-3.
IBNet: An Iceberg Semantic Segmentation Network Integrating Multiple Scales and Attention
Authors: Han Fenglei , Zhao Wangyuan , Xue Yanzhuo , Wu Yuliang , Peng Xiao , Zhang Jiawei 
Published: August 2024

Abstract
Fine-grained semantic segmentation of iceberg visual images obtained from low altitude is of great significance for ship navigation and ecological surveys, which can be regarded as the key technology of iceberg management. However, because of the bad weather in Polar regions and resource constraints, the similar texture of different ice images is the major challenge for iceberg identification, which may lead to false navigation for the ship controlling system. The main purpose of this paper is to generate accurate pixel-level iceberg image segmentation and prediction under poor sea ice optical vision acquisition conditions. A new feature extraction network IBNet with multi-scale features and double-layer attention mechanism is proposed for pyramid pooling module layer to realize weighted fusion. This learning-based approach considering six kinds of iceberg backgrounds in the scene of polar regions can be applied to support obstacle avoidance algorithm for Polar region navigation. By comparing PA, MIoU and other parameters with the other methods, IBNet performs obvious advantages in semantic segmentation task of icebergs in polar regions.
Numerical Investigation on Vibro-Acoustic Characteristics of a Metamaterial Plate Under the Excitation of Turbulent Boundary Layer
Authors: Dong Wenkai , Huang Zhangkai , Wang Ting , Chen Meixia 
Published: August 2024

Abstract
Flow-induced vibration is an important noise source for mechanical transportation equipment. In recent years, metamaterials have emerged as a novel approach to mitigate vibration and noise, garnering extensive research and recognition. However, research into the behavior and control of metamaterials under flow-induced excitation remains insufficient. To address this issue, this paper proposed a stiffened metamaterial plate to investigate its control performance for flow-induced vibration and noise. An uncorrelated wall plane wave (UWPW) technique is utilized to convert the stochastic problem into a collection of determinate loading scenarios, which are solvable via the finite element method. The effectiveness of this method has been validated by comparing the results with those obtained from conventional analytical approaches. This method allows for a comprehensive prediction of the metamaterial plates’ reaction to the turbulent boundary layer excitation. The findings reveal that within its bandgap range, the metamaterial plate is highly effective in attenuating vibration and noise. The addition of stiffeners to the plate elevates its first natural frequency, thus diminishing the overall vibration noise response. This paper serves as a reference for controlling vibrations under flow-induced excitation.
Energy Fluctuation of Floating Photovoltaic Solar Panel due to Wave-Induced Motions
Authors: Huang Luofeng 
Published: August 2024

Abstract
Solar photovoltaic is predicted to be the most widely used energy method in the future. However, the expansion of solar panels is currently limited by scarce land and lake spaces. To meet the world’s future clean energy target, floating solar panels are expected to be deployed on abundant ocean space, but floating solar panels on the ocean will be subject to loads and motions induced by waves. In particular, a continuous rotation can cause the solar panel surface to constantly change its sunlight intake angle, which could lead to a loss of energy. To investigate this phenomenon, a novel interdisciplinary experimental facility has been established, where a solar simulator was installed on top of a wave tank. A floating solar unit is placed in high-concentration light beams and subject to wave-induced motions. Its motions are measured and related to the power output. It was found that the average power output oscillates due to the motions, and an evident power loss was shown by the rotational motion. For all the tested wave conditions, the highest pitch amplitude of 6.7° corresponds to a significant level of 12.7% average power loss. Overall, the work presents a novel experimental approach and results that can estimate power output for floating solar projects in wave environments. The results also highlight the importance of considering wave attenuation technologies to avoid direct wave interaction with floating solar units.
Development of a Test Machine and Wear Test to Reproduce the Wear Caused by the Mooring Chain Connection of Floating Wind Turbines Sliding in Water due to the Movement of the Floating Body
Authors: Gotoh Koji , Murakami Koji , Utsunomiya Tomoaki 
Published: August 2024

Abstract
In order to ensure the safety of floating offshore wind turbines, it is essential to establish a method for assessing the amount of wear on the mooring chain. This allows maintenance costs to be considered at the planning stage of the installation.
In this study, an experimental system was constructed to reproduce the wear behavior of a mooring chain with dimensions similar to those of the in-service machine, when it is completely submerged in water. The wear behavior was investigated under several tension conditions, and it was confirmed that the wear behavior in a fully submerged environment was different from that in air or in liquid drops. In addition, a discussion on the mechanism of the wear progression stages of mooring chains was presented.
Radiation and Scattering of Water Waves by a Submerged Elliptic Disc
Authors: Gayen Rupanwita , Farina Leandro , Hoque Ajijul , Datta Ranadev 
Published: August 2024

Abstract
In the present paper, the radiation and scattering by an elliptic disc submerged in infinite-depth water are investigated. The problems are solved by reducing them to two-dimensional hyper-singular integral equations over the surface of the disc. A spectral method is used to solve the integral equation numerically. Numerical results are presented for different hydrodynamic quantities related to scattering and radiation by the disc. Initially, the formulation is validated against published results for a circular disc. Once it is found satisfactory, a rigorous parametric study is conducted for the elliptic disc. The primary focus of the presented study is to investigate the dependence of several physical quantities such as added mass, damping coefficient, and exciting forces on the depth and geometry of the disc. From the results, it is observed that when the body is near the free surface, the pressure field around the body changes abruptly and resonance occurs. Also, by solving the radiation problem, it is seen that for the elongated body, that is, where the ratio of the semi-major axis to the semi-minor axis is high, added mass and damping coefficient change significantly. The present study may be useful as a benchmark study. Also, in the domain of ocean energy, this study can give a rough idea about the design of an oscillator. At present, bases of all the oscillators are modelled as circular. This study reveals that an elliptic base might be useful as well.
Analysis of Fracture Parameters for Compact-Tension-Shear Specimen of Orthotropic Materials
Authors: Jin Pengfei , Liu Zheng , Chen Xu , Wang Xin 
Published: August 2024

Abstract
Treating orthotropic materials as isotropic for strength analysis and design can introduce significant errors, resulting in considerable safety risks. Furthermore, in practical conditions, cracks often exhibit mixed-mode fracture behavior, and the combination of orthotropy mechanics gives rise to an even more complex stress field in the vicinity. In this context, performing Compact-Tension-Shear (CTS) tests is a promising research methodology to determine fracture toughness of orthotropic materials in mixed mode I&II. Therefore, this study conducted a comprehensive two-dimensional finite element analysis (2D FEA) on orthotropic CTS specimens to assess critical parameters in fracture toughness including stress intensity factors (SIF) and crack mouth opening displacement (CMOD) compliance. The analysis matrix encompassed a wide range of material orthotropy, crack length ratios, and loading angles. Results showed that the impact of orthotropy varies under different geometries and loading angles, while different fracture parameters exhibit varying degrees of sensitivity to orthotropy. The obtained results would contribute to the development of fracture toughness testing methods for orthotropic materials under mixed-mode loading and provide a reference for standardization in the process.
Hydroelastic Analysis of Floating Photovoltaic Floater Under Regular Waves
Authors: Leventopoulou Theano , Dai Jian , Jiang Zhiyu 
Published: August 2024

Abstract
The need for renewable energy is increasing and limited land space for installations has led to the rise of floating photovoltaic (FPV) systems, a promising and relatively new technology for harnessing solar power on water surfaces. Apart from the design and the construction of the FPVs, the hydroelastic problem posed by water waves on plate-like floating structures has a considerable value in the offshore application. This study focuses on the frequency-domain hydroelastic analysis of a recently proposed FPV concept with rope connection. In numerical modelling, each FPV float is simplified as a rectangular plate and modelled by using Mindlin plate elements considering only the vertical degrees of freedom. After a mesh convergence study, the FPV systems with one float and two interconnected floats are studied. Through parametric studies considering different wave headings, periods, and connector stiffness, we compare the distributions of displacement, and bending moments along the float for each system. This study serves as a reference for understanding the hydroelasticity effect of simple FPV systems under different environmental conditions and mechanical connections.
Cross Sectional Mechanical Characteristics and Sensitivity Analysis of Unbonded Flexible Risers Under Torsional Loads
Authors: Ma Weilin , Zhang Xiansheng , Yang Yongchun , Chen Changlong 
Published: August 2024

Abstract
Unbonded flexible risers have complex structures and numerous structural parameters. The torsional loads carried by each structural layer lead to different levels of coupling deformations of layers. These deformations bring challenges to the structural design and mechanical characteristics analysis of flexible risers. This study establishes the theoretical model of flexible risers under the torsional loads according to the law of conservation of energy and the deformation geometry theory. Depending on the material properties and structural forms of each layer, this study divides the layers of flexible risers into three categories: cylindrical layer, metal spiral layer and polymer spiral layer, and derives the expressions of torsional loads and torsional stiffness. The calculation program in this study is compiled with MATLAB software to calculate the mechanical properties of flexible risers under clockwise and counterclockwise torsional loads. This study analyzes the influence of structural parameters on the torsional performance of flexible risers. Calculation and analysis of the influence of structural parameters on their mechanical properties can provide not only the further insight into the mechanical principles of each structural layer, but also the reference for structural design and optimization of flexible risers.
Piloting of Vessel Technical Index
Authors: Guo Bingjie , Tvete Hans Anton , Vartdal Bjørn Johan , Wang Shuai 
Published: August 2024

Abstract
Studies have shown that about half of the reduction potential can be achieved through adopting the fuel saving measures. However, the lack of information, uncertainty about hidden costs/benefits, information asymmetry between stakeholders, conflicts of interest and split incentives etc. hinder the application of the fuel saving measures. To evaluate ship technical performance and efficiency of fuel saving measures in a transparent way is critical to remove the barriers. Thus, DNV has proposed Vessel Technical Index (VTI), which isolates the technical condition of in-service ship, by accounting and adjusting for the relevant operational factors and weather effects. This index can evaluate ship technical performance in an effective and transparent way, which can enhance the cooperation between stakeholders to remove barriers that hinder the application of fuel saving measures, which also can help ship owners to optimize ship maintenance. VTI index is based on some measurement parameters, which need to be collected, processed, and synchronized. The measurement data always includes noises, and the physical models to correct the operational factors and weather effects also have model uncertainty. Thus, a systematical method to collect data, process data, calculate VTI index and evaluate VTI uncertainty has been developed, which will be presented in this paper. Three use cases of the VTI index will also be discussed.
A Modeling Method of Predicting Service Life at Crack Threshold Stage for Tensile Armor of Flexible Pipes Under SCC-CO2 Environment
Authors: Ye Wenye , Yang Qi , Ribeiro Marcelo , Ribeiro Carlos , Zhu Linfa , Alvino Alberto , Roberts Andrew , Tan Zhimin 
Published: August 2024

Abstract
Cracks triggered by Carbon Dioxide initiated Stress Corrosion Cracking (SCC-CO2) have been identified as a new failure mode in flexible pipes, yet a method of predicting its occurrence, especially the stage of crack initiation (T1) is lacked in the industry. The root cause of SCC cracks is complex, the experiment observation shows the cracking may initiate from different locations and grow along different paths. As a starting point, this paper introduces a methodology of T1 prediction on the basis of equivalent initial flaw size (EIFS) theory and also back-extension of Paris linear section. It implies the condition that SCC-CO2 cracks initiate from corrosion pits and propagate through grain boundaries. The influential factor from environment mainly includes the stress utilization factor (UF), CO2 fugacity and operational temperature. After the preliminary calibration using data from dissected pipes retrieved from different oil fields, the model is able to predict typical trends, agreeing with the most field observations. Investigation continues to understand the mechanisms leading to some specific deviations, and to explore potential solutions and improvements. The presented approach is anticipated to provide a reliable and consistent prediction of nucleation duration in determining SCC-CO2 service life. Furthermore, the model in this methodology will be further calibrated and validated against future tests and field experiences.
Numerical Study on the Fluid Interactions and Gap Resonance Between Two Adjacent Floating Bodies
Authors: Huang Lin , Yu Liwei , Wang Shuqing 
Published: August 2024

Abstract
The analyses of fluid interactions between multiple floating bodies have been of practical importance in the field of ocean engineering, such as float-over installation, offshore side-by-side operation and floating solar photovoltaic (FPV) system with array of adjacent floating bodies. Waves dominated by the diffraction potential show substantial wave surface elevation at gaps in multiple floating bodies, so there is an urgent need for an in-depth mechanistic study of this problem.
In this study, a side-by-side operation ship model of two ships with identical main scales is taken as the research object, and the potential flow theory is taken as the basic framework to establish the three-dimensional boundary element method based on the free surface Green’s function which is applicable to the analysis of wave interaction response. The self-developed floating body hydrodynamic calculation program is used to simulate the wave surface at the gap of the two-ship model under different frequency waves.
It was found that at high frequencies, a large increase in the wave surface occurs in the gap of multiple floating bodies, and that the wave surface rise is mainly caused by diffraction waves.
Effects of Needle Peening on Fatigue Strength of Aluminum Alloy Welded Joint Containing a Surface Defect
Authors: Fueki Ryutaro 
Published: August 2024

Abstract
This study investigates the impact of needle peening (NP) on the fatigue strength of aluminum alloy welded joints with an artificial semicircular slit at the weld toe. Uniaxial fatigue tests were performed on specimens, both with and without a slit, at a stress ratio of 0.05. The fatigue strength at 2 million cycles increased by 11%–100% due to NP treatment. Notably, specimens with 1.0 mm slit depths demonstrated fatigue strengths equivalent to those without a slit, attributed to the introduction of substantial deep compressive residual stresses. This finding suggests that NP can effectively mitigate semicircular slits less than 1.0 mm, enhancing the reliability of aluminum alloy welded joints. Such slits, typically challenging to detect via standard nondestructive inspections, can be addressed efficiently through NP.
Numerical Calculation and Analysis of Motion Response of Moonpool Floating Wind Turbine
Authors: Li Mingxuan , Chen Junxuan , Zhang Xinshu 
Published: August 2024

Abstract
The motion response of a floating wind turbine is tightly controlled by rigorous requirements, as overly vigorous movements may lead to damage of the turbine equipment. Consequently, mitigating the motion response of the wind turbine is of paramount importance. The moonpool, defined as an opening vertically aligned with the sea surface, penetrating the platform and connected to the sea, can afford a relatively stable operating environment for internal operations. In this study, the SESAM software developed by DNV-GL is applied to utilize numerical simulation to conduct frequency-domain analysis of the hydrodynamic performance of a barge-style floating wind turbine with a moonpool under both survival and operating conditions. The research focuses on investigating the motion response characteristics of the wind turbine platform. The parameters of the barge-style floating wind turbine are referenced from [1]. The obtained resonant frequencies of various orders of the moonpool are compared with experimental results, validating the reliability of the calculations. Additional comparisons are made regarding platform added mass, radiation damping, and six-degree-of-freedom motion response, identifying abrupt changes in the turbine’s motion performance near resonance frequencies. Furthermore, adhering to DNV standards, the study evaluates the safety of the wind turbine platform under two design conditions based on maximum tilt angle and maximum acceleration of the nacelle position. Finally, a parametric analysis of the platform is conducted. Using platform length, moonpool length, and platform molded depth as independent variables, different principal dimensions of the wind turbine platform are estimated based on scale ratios. Subsequently, an analysis of the turbine’s motion response and safety under various main dimensions is performed. The present study indicates that enhancing the safety of a floating wind turbine can be achieved by increasing the platform length and reducing the platform molded depth appropriately. Additionally, enlarging the dimensions of a rectangular moonpool appropriately contributes to further enhancing the safety of platform under harsh sea conditions.