bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Gaussianity of Wind and Wave Field Data
Authors: Laface Valentina , Arena Felice 
Published: September 2023

Abstract
This work deals with an analysis of simultaneous wind and wave records collected at Natural Ocean Engineering Laboratory (NOEL) of Reggio Calabria, Italy. NOEL is a field laboratory located in the Messina’s Strait which is characterized by particular wind conditions that generate sea states representing small scale models of typical ocean storms. Wind data are collected by an anemometer located on a nearshore platform at 5 meters height above mean water level recorded with a frequency of 4Hz. Sea surface elevation is recorded by ultrasonic probes at intermediate water condition with a frequency of 10Hz. Wind data are provided in terms of wind speed fluctuations, while wave data in terms of sea surface elevation. Over time intervals compatible with the stationarity assumption, both wind speed fluctuations and sea surface elevation are represented by a gaussian process characterized by a given frequency spectrum. However, real data exhibit significant deviations from gaussian distribution. This work is focused on the analysis on whether wind and wave records are gaussian or not, elucidating analogies and differences between wind and wave processes. Results show that both wind and waves are asymmetric and non-linear. Waves are right skewed, having crests greater than troughs, while wind speeds fluctuations may be both right and left skewed, revealing that peak amplitudes can be larger than lulls and vice-versa. Deviation from gaussianity for wind speed can be larger than for waves.
Exploration of Strategies to Improve Continual Learning From Irregular Sequential Drilling Data
Authors: Pacis Felix James , Wiktorski Tomasz , Ambrus Adrian , Alyaev Sergey 
Published: September 2023

Abstract
Economic and environmental objectives incentivize drilling wells faster, increasing the rate of penetration (ROP). A prerequisite for ROP optimization is an accurate ROP model that provides the expected rate given a set of drilling inputs and in response to downhole parameters in real-time. Relatively seldom and often different drilling operations make it difficult to collect a large dataset for supervised training of universal ROP predictors. Thus, ROP Deep Learning (DL) models often suffer from poor generalization. This work introduces continual learning as a new paradigm for data-driven ROP modelling. We subdivided historical drilling data from the Volve field and Marcellus Shale into smaller sections to imitate actual operations with irregular time-series data coming sequentially. In continual learning, each incoming section serves first as a testing set and is subsequently added to the training set. Using transfer learning, we continuously fine-tune the current DL model with varying amounts of recent data to adapt it to new conditions. Continual learning improved the ROP prediction accuracy for both J-shaped-well and horizontal-well test cases compared to the conventional one-off training paradigm. Furthermore, we documented the model performance for different fine-tuning configurations through a series of sensitivity analyses. We also discussed the challenges and trade-offs when implementing continuous learning for ROP prediction.
Complexities of Capturing Large Plastic Deformations Using Digital Image Correlation: A Test Case on Full-Scale Pipe Specimens
Authors: Johnson Tyler , Langer Doug , Frigon Ethan , Timms Chris , Kobayashi Shunichi , Tsuru Eiji 
Published: September 2023

Abstract
This paper identifies the challenges associated with using digital image correlation (DIC) measurements for full-scale bending tests that result in large deformations, and it describes techniques to address these challenges. Full-scale bend tests experimentally determine the strain capacity of line pipe, which is a critical parameter in strain-based design and assessment. DIC is a preferred measurement technique for these tests as it provides non-contact, full-field measurements of the pipe deformation over time.
The primary challenges identified in using DIC for full-scale, large-deformation pipe testing relate to the speckle pattern, imaging system, and DIC performance measurement. A series of procedure and equipment improvements have been developed to address each of these challenges and to help improve the overall accuracy of the measurement system.
The successful implementation of the DIC technique is illustrated through a recent full-scale pipe bend test of a 4.45-metre-long section of 24-inch diameter, X65 pipe. The pipe was subjected to severe bending (up to a 51° bend angle), resulting in the formation of a self-contact buckle. The test was monitored using four DIC systems (each system consisting of stereo cameras) incorporating the recommended procedure and equipment improvements identified herein. The DIC results were validated against conventional strain gauges.
Research on a General Virtual Visualization System of Finite Element Analysis Result Data of Ship Structure
Authors: Wei Pengyu , Li Chuntong , Wei Naikun , Jiang Ze , Luo Xiaomeng , Wang Deyu 
Published: September 2023

Abstract
The sharing of finite element analysis (FEA) data during the design process is a key requirement for success in collaborative design environments. However, the efficiency of sharing finite element analysis (FEA) data using a standardized neutral format is still relatively low because the format must accommodate a wide range of data types produced from multidisciplinary analysis applications. This paper proposes a strategy for efficient visualization and sharing heterogeneous FEA data in the collaborative design and review of ship structures. Our approach achieves substantial data compression by storing only essential FE information. An object-oriented approach is adopted maximize the efficiency of managing multidisciplinary data, our format also allows the use of multi-level management of FEA visualization data. The FEA model data and results are transformed into a common visual data architecture that is easily interpretable in virtual reality applications. We implemented a system based on our approach, several examples from commercial FEA systems are provided to demonstrate the effectiveness of the format. The virtual visualization of these complex FEA data effectively enhances the efficiency of scientific communication, model evaluation and validation, and interdisciplinary discussion of research findings.
Analytical, Numerical, and Field Data Investigation for Deriving the Condition of Stick-Slip Drill String Vibration
Authors: Kaneko Tatsuya , Inoue Tomoya , Wada Ryota , Katsui Tokihiro , Suzuki Hiroyoshi 
Published: September 2023

Abstract
Several studies have been conducted on the stick-slip type of torsional vibration, which reduces drilling efficiency and sometimes damages drill bits and pipes, using numerical experiments, small-scale model experiments, or field data on the land rig. However, an analytical investigation into stick-slip conditions or a field data investigation of deepwater drilling has not been sufficiently studied. This study derives the conditions for stick-slip occurrence through analytical, numerical, and field data investigations and discusses a method to reduce stick-slip vibration.
First, we derive a simple expression for stick-slip using an analytical solution of a single mass-spring-damper model. Additionally, we numerically experiment using a multi-mass model to consider the mass distribution that cannot be considered in the analytical solution. Furthermore, we analyze the field data from deepwater drilling and experiment with a numerical model to examine the actual phenomena.
As a result, the analytical and numerical investigations have shown that stick-slip can be prevented by appropriately adjusting the rotational speed and the weight on bit. However, the field data investigation showed that the forced torsional vibration due to the vibration of the weight on bit was predominant in deepwater drilling. In this case, suppressing the amount of fluctuation of weight on bit is crucial to reduce the torsional vibration.
Hydrodynamic Modelling of Modularized Floating Photovoltaics Arrays
Authors: Zhang De-Qing , Du Jun-Feng , Yuan Zhi-Ming , Zhang Ming , Zhu Feng-Shen 
Published: September 2023

Abstract
Large arrays of floating photovoltaics (FPV) are emerging to be an attractive solution to renewable energy production and ocean space utilization. FPV arrays are typically buoyed by hundreds of modularized floating bases arranged in ocean surface. The total performance of the FPV arrays is significantly affected by the hydrodynamic interactions between these individual floaters. As the size of the array increases, more time will be required to calculate the entire hydrodynamic properties. From the engineering point of view, it is a challenging task to fully consider the radiation interactions among the modularized FPV floaters. In fact, when the distance between two floating bodies is large enough, their interaction will gradually vanish. The present study developed a cut-off scheme to improve the computational efficiency while providing a reliable prediction of the interaction effects in engineering practice. A cut-off radius is introduced in this scheme to determine the coupling range in which the radiation hydrodynamic interactions should be considered. The cut-off radius is determined by three parameters, including the modular shape, wave frequency and accuracy requirement. Several arrays of rectangular FPV bases were taken as examples to show how to quantify the radiation interactions and find an optimal cut-off radius. The effect of wave direction, gap distance, and connection type were also investigated. The results from the validation case showed that the hydrodynamic interaction can be well predicted using the proposed cut-off scheme, while more than half of the computational time can be saved.
Fault Diagnosis of Rolling Bearing Under Marine Noisy Environments and Varying Working Conditions
Authors: Gao Chao , Guo Yongjin , Han Bing , Liang Xiaofeng , Wang Hongdong , Yi Hong 
Published: September 2023

Abstract
Rolling bearings are the core components of ship rotating mechanism, and accurate fault diagnosis has great significance in preventing serious failures of them and performing effective maintenance strategy during navigation. However, varying working conditions and cabin noisy environment would affect the monitored signals of bearings, resulting in the degradation of diagnosis performance. To address this problem, a new fault diagnosis method combining the Denoising Convolutional Auto-Encoder (DCAE) and the multi-scale Residual Net (MSRNet) is proposed in this paper. The DCAE model is designed for denoising. The fully-connected layers of Denoising Auto-Encoder (DAE) are replaced with one-dimensional convolutional layers. In the MSRNet, multiple-size convolutional kernels are utilized in each residual block for extracting multi-scale features of the signals. Typical bearing failure dataset is used for validation. The experimental results show superior performance on noise resistance and domain adaptation of the proposed method under noisy environments and varying working conditions.
Numerical Simulation of Nonlinear Regular and Irregular Waves Based on HOS-CFD Method
Authors: Liu Wuyang , Yu Jiawei , Dong Guohua , Yao Chaobang , Meng Fanliang 
Published: September 2023

Abstract
In naval architecture and ocean engineering, efficient and accurate generation and propagation of nonlinear waves is an important problem to be solved. Due to the use of pseudo-spectral method and fast Fourier transforms (FFTs), High-Order Spectrum (HOS) is an efficient and stable potential flow theory model for simulating nonlinear waves. However, the HOS method cannot consider the effect of viscosity, which makes it difficult to solve the interaction problem between wave and structure. Meanwhile, the CFD method consumes a lot of computational time and resources to solve a large viscous wave field. Therefore, this paper intends to build a HOS and CFD coupling calculation model: The regular and irregular wave fields generated by the HOS method are reconstructed and interpolated, and then the nonlinear wave field information is transmitted to the computational domain from the boundary velocity inlet of the in-house viscous solver HUST-SHIP. The influence of mesh size on coupling is discussed, and the accuracy of the coupling method is validated by simulating various types of waves. The generation of nonlinear wave field and the coupling with viscous flow solver are obtained, which lays a solid foundation for the subsequent analysis of the interaction between nonlinear waves and ships and marine structures.
A Tensile Test and Finite Element Analysis of DH36 High-Tensile Steel at Cryogenic Temperature
Authors: Nubli Haris , Kim SangJin , Sohn Jung Min , Jung Dongho , Cho Joung Hyung 
Published: September 2023

Abstract
Excessive exposure to LNG weakens and causes a brittle fracture to steels. Therefore, all risks that can lead to LNG spillage must be minimized or mitigated by applying a cryogenic temperature resistance material to the ship’s structure. Higher strength steel that considers low temperature such as DH grade is recommended to be used for ships carrying LNG cargo.
In this study, material fracture idealization of DH36 steel under a tensile load and low temperature is presented. The fracture strain of the steel could be affected by temperature reductions due to the hardening effect, as well as the element size in the Finite Element (FE) model would influence the fracture strain behavior. Thus, the stress-strain curve of DH36 has to be calibrated for the use in FE model. A sensitivity analysis with temperatures and element sizes was presented. The strain rate effect was neglected since the quasi-static mode was performed in the tensile test. The temperature is applied from 25°C (room temperature) to −160°C. The element sizes of 0.5mm to 5.0mm were used in the FE model of the specimen. This investigation found that the ultimate tensile and yield stresses were increased with a slightly increased upon the fracture strain along with the decrease in temperature. Furthermore, the procedure of the tensile test and FE analysis are discussed in this paper.
Progressive Collapse Behavior of Ship Structures Considering Fluid-Structure Interaction Effect
Authors: Zhou Ji , Pei Zhiyong , Wu Weiguo , Ding Jianliang 
Published: September 2023

Abstract
The collapse behavior of ship structures has great significance to structural safety and reliability design. In the present research, a nonlinear finite element method considering the fluid-structure interaction is proposed to analyze the progressive collapse behavior of a typical container ship test model.
The fluid-structure interaction analysis system is constructed adopting STAR-CCM+ and ABAQUS to obtain the moment curvature relationship with time history. The structural collapse response under series wave conditions varying wave length and height is investigated and discussed.
The proposed nonlinear analysis considering the fluid-structure interaction can provide a rational way for evaluating the collapse behavior of ship structures in waves. The obtained results have reference for the progressive collapse behavior of ship structures.
Investigating Damage Initiation in Wind Turbine Blade Coating Under Repeated Raindrop Impacts
Authors: Kuthe Nikesh , Pandey Vibhuti Bhushan , Ahmad Suhail , Mahajan Puneet , Mishnaevsky Leon 
Published: September 2023

Abstract
The Wind Turbine Blade (WTB) coating is a protective layer that sustains repeated raindrop impacts. These impacts cause cyclic stresses, fatigue, and the resulting erosion of the leading edge of the blade coating. The high-intensity rains in India make this problem more critical. The presence of voids (manufacturing defects) in the coating leads to local stress concentration and enhances the intensity of erosion. This erosion causes an increase in the drag coefficient and a reduction in the lift coefficient leading to an underperformance of the turbine. Several studies are reported in the literature to understand the damage estimation of the coating. However, the effects of the voids radii and their locations on the rate of degradation of the coating due to repeated impacts need further investigation. In the present study, it is learnt that voids in the coating cause faster damage propagation. That results in the deterioration of the impact-damping performance, causing an early failure of the material. The study also demonstrates that in the case of coating without voids, the damage starts from the surface and travels downwards. Whereas, in the case of coating with voids, the damage accumulates rapidly in its vicinity. The study is performed in two steps. Firstly, the stresses in the coating are computed using a finite element model employing smoothed particle hydrodynamics (SPH) in ABAQUS/Explicit. Hence, the fluid-solid interaction study is performed. In the second stage, the fatigue damage of coating is predicted by employing the continuum damage mechanics (CDM) approach. The comparison of results in the above two cases demonstrates that the present model with voids is found to be more realistic for estimating nonlinear damage accumulation, micro-cracks initiation and growth. Thus, it is presently adopted to visualise the effect of voids radii and their locations on WT coating subjected to rain-induced fatigue. The results obtained by the present realistic model are validated with the established experimental observations.
Numerical Study on the Evolution of Vortices Influenced by Downstream Undulating Foil With Different Lateral Distances
Authors: Wang Pengfei , Li Ruoxin , Yu Kai 
Published: September 2023

Abstract
In this work, we numerically simulate the hydrodynamic performance of an undulating foil at different lateral distances behind a cylinder, focusing on the evolution of the vortex street at each stage. Computations are conducted using unsteady incompressible Navier-Stokes solver with a moving adaptive mesh for laminar flow. We found that the secondary vortex induced by the Karman vortex street at the leading edge of the foil is the main reason for the thrust increase of the foil. The evolution of vortices corresponding to different lateral distances are different. A small lateral distance between the cylinder and the foil could make the vortex evolution complex. Meanwhile, the secondary vortex could be generated easily, and the foil could gain a large thrust. As the distance increases, the lift force of the foil tends to increase first and then decrease. An optimal distance exists at which lift reaches its maximum value, and this is also related to the distribution and strength of the vortex.
Data-Driven Modeling of Long-Term Riser Response to Irregular Waves Considering Wave Directionality
Authors: Cheng Ankang , Low Ying Min 
Published: September 2023

Abstract
Prediction of riser response to irregular waves has long been of industrial interest. But numerical simulation is often time consuming due to system nonlinearity and excitation stochasticity, especially in the context of reliability assessment where tons of repetitions are targeted. In this regard, data-driven modelling techniques have been proposed and applied by many researchers in the past decades. However, most established surrogate models were constructed in essence for single sea states and require vessel motions or their derivatives for input. These facts preclude them from fully playing the role of numerical models in prediction. In this paper, a data-driven model of long-term riser response considering wave directionality is developed based on nonlinear autoregressive networks with exogenous inputs (NARX) using fluid velocities. The adoption of fluid velocities stems from wave physics. It not only guarantees the good model performance in conjunction with the ensemble technique, but also allows prior knowledge about ocean environment to apply. Through design of experiments, only a limited number of numerical simulations for riser response to random short-term sea states need to be conducted to prepare data for training networks. The resultant model works well in the most critical case where all long-term wave variables including wave direction come into effect. A floating production system is used as an example for demonstration.
A Monte Carlo Approach for VIV Fatigue Damage Estimation of Subsea Pipelines Subjected to Design, Installation and Operational Uncertainties
Authors: Sales Leonardo , Mohammed Mohammed , Gil Cyprian 
Published: September 2023

Abstract
Obtaining a realistic prediction of the fatigue damage of pipelines employed in the subsea industry is vital for safe operations, as they are permanently subjected to wind-sea waves, swell and marine currents. Considering pipeline fatigue damage due to vortex-induced vibration (VIV) over its life cycle is critical in the design phase. Several VIV fatigue damage prediction models have been and are being developed by oil companies and research institutes. Uncertainties in the input data, such as in the effective axial tension, wall thickness, structural damping, water depth, and others, can influence the selection of materials, welding procedures, fulfilment of safety criteria, and other important decisions; therefore, on the total cost of the project. Reliable predictions of VIV fatigue damage are vital to controlling the degradation and ensuring the integrity of the operation at an optimized cost.
This paper aims to evaluate the variability of VIV fatigue damage prediction when uncertain inputs in wall thickness, water depth, structural damping, gap height, effective axial force, and Hi-Lo weld cap are considered. To this, a sensitivity analysis is conducted and an in-house software used for estimating VIV fatigue damage over the pipeline life cycle is employed combined with a Monte Carlo simulation. A case study based on a synthetic Norwegian offshore oil field is used. The information can support oil and gas companies in focusing on the most critical input parameters and uncertainties when carrying out a VIV fatigue damage analysis in new projects, and to help visualize the uncertainties in free span analysis.
Wind Turbine Load Monitoring During Model-Test in a Wave Basin
Authors: Gueydon Sébastien , Bayati Ilmas , Bosman René , van Kampen Wouter , de Ridder Erik-Jan 
Published: September 2023

Abstract
For the testing of floating wind turbines in a wave basin, several methods have been developed to include the wind turbine loads acting on the floating foundation. To simplify, there is one main choice for the modelling of the wind turbine loads at the scale of the basin: using a physical rotor in a wind field, or using hybrid methods where the wind turbine loads are computed and applied by actuators to the model. Each approach aims at reproducing the loads that the wind turbine generates at the Froude scale chosen for the construction of the model. Transferring these loads can therefore be seen as a step that is common to all methods. While these loads are essential for the modelling of the wind turbine and its interaction with the floating foundation, they are not yet systematically measured nor reported in all basin tests of a floating wind turbine. Most surprisingly, the benefit of measuring of the wind turbine loads transferred to the floating foundation are not explicitly mentioned in the main guidelines on how to test floating wind turbines [e.g.: ITTC]. This paper gives some examples of diverse test set-ups where these loads are measured and it explains how the wind turbine thrust is analytically retrieved from these measurements. It also emphasizes why monitoring the loads actually transferred to the floater adds up to the quality of the test results and confidence in the experiments.