bluuebunny/crossref_metadata_2025_split huggingface dataset:
Early Stuck Pipe Detection Using Graph Attention Machine Learning
Authors: Inoue Tomoya , Nakagawa Yujin , Kaneko Tatsuya , Wada Ryota , Miyoshi Keisuke , Abe Shungo 
Published: September 2023

Abstract
Early detection of stuck pipes during drilling operations is crucial and challenging. Some of the studies on stuck detection have adopted supervised machine learning approaches that employ datasets for “stuck” and “normal”. However, that is, for early detection before stuck occurs, the application of ordinal binary classification in supervised machine learning has presented several elemental concerns, such as limited stuck data, and lack of an exact “stuck sign” before occurrence. Our previous studies proposed an unsupervised machine learning approach using data on the normal activities with LSTM-AE (Long Short-Term Memories and Autoencoder) and the mixture probability mode, and presented the possibility of predicting a stuck pipe.
These approaches independently handle the drilling data, which are multivariate time series data. However, there are relationships among some data. To improve the prediction performance to utilize the dependencies among the drilling data must be utilized. Hence, this paper applies graph neural network that can handle the dependencies between data. In addition, self-attention, a state-of-the-art machine learning approach that can determine the dependencies between multiple input data is applied.
This study performs the stuck prediction with the graph attention unsupervised machine learning using the scientific drilling data containing few stuck events to discuss the possibility of early stuck detection before stuck occurrence and the advantage of graph attention network.
Nonlinear Fourier Analysis Using Quasiperiodic Fourier Series
Authors: Osborne Alfred R. 
Published: September 2023

Abstract
“Linear Fourier analysis” is based on the application of “periodic Fourier series” to a wide range of wave simulation and data analysis problems. A key feature of the method is the direct computation of the “correlation function” and its Fourier transform which is the “power spectrum.” A key idea in these applications is the assumption that the “phases” of the periodic Fourier transform are “random numbers on zero to two pi.” The method leads to simple ways to compute the “coherence functions” and “transfer functions” between two signals. Many books have been written about the “linear model” and its myriad applications. In the present talk I address the infinite number of “nonlinear wave equations” that are solvable by the “periodic/quasiperiodic inverse scattering transform” and, amazingly, I show how such equations are solvable with “quasiperiodic Fourier series.” This means that all operations of the nonlinear problems of water waves are isomorphic to those of the linear problem! All operations that one can conduct for the linear problem with periodic Fourier series can also be conducted for nonlinear problems with quasiperiodic Fourier series: This means the correlation function, power spectrum, coherence functions, and transfer functions for the nonlinear problem can be computed in analogy with the linear problem. This further means further the nonlinear problem is just as easy to work with as the linear problem! I give a fast Fourier transform for quasiperiodic Fourier series and show how to conduct numerical simulations of nonlinear waves using the procedure. The methods discussed here provide for a new future in which nonlinear problems are just as easy to treat as linear ones. This work emphasizes one dimension in space, but two-dimensions are easily found by extension.
Combining Model-Based and Data-Driven Methods to Estimate the Roll Motion of a Spread-Moored FPSO
Authors: Cotrim Lucas P. , Huang Alex S. , Bisinotto Gustavo A. , Cunha Rodrigo Da S. , Barreira Rodrigo A. , Costa Anna H. R. , Gomi Edson S. , Tannuri Eduardo A. 
Published: September 2023

Abstract
The roll motion of a Floating Production Storage and Offloading (FPSO) unit has complex interactions that are difficult to be modeled precisely: non-linear damping depending on the motion amplitude and velocity and influence of the mooring lines forces, for example. In order to improve the estimation of the roll motion of an FPSO, a new model is proposed combining the already established physics model with a regression neural network developed to calculate the residue between the physics model and the vessel’s actual measured motions. More specifically, the regression neural network corrects the maximum roll amplitude and its standard deviation obtained from a time domain simulation of the physics model.
This study considers a typical spread-moored FPSO located offshore on the Brazilian coast. The physics model considers the 6 degrees of freedom dynamics of a floating body subject to different drafts, mooring lines and environmental forces (wind, current, waves). A conventional Multi-Layer Perceptron (MLP) neural network is trained with data from more than 44,000 samples taken from actual environmental conditions and corresponding measurements of the platform roll motion between the years 2007 and 2014. The resulting hybrid physics-MLP model receives as input the environmental conditions and the FPSO draft, executes a 1-hour simulation of the physics model, derives the maximum roll amplitude and its standard deviation, and then the MLP compensates for the expected residue of the physics model. By adding information from real measurements to the mathematical model, the previously non-modeled effects are now considered.
The present paper concludes that the hybrid architecture combining a physics-based model and an MLP has improved the estimation of the roll motion, correcting the overdamping previously observed.
Numerical Study on Green Water on Deck and Impact Loads of a Ship Model Advancing in Head Wave
Authors: Dong Guohua , Yao Chaobang , Liu Wuyang , Feng Dakui 
Published: September 2023

Abstract
Under rough sea conditions, the green water on the ship deck may induce great impact loads on the hull structure, which will cause serious structure damage and pose a threat to the safe ship navigation. Therefore, the study of green water and the impact load is particularly important. In this study, the numerical verification and validation of green water on deck and impact load is carried out. Commercial viscous flow CFD software STAR-CCM+ is used for calculation. The unsteady Reynolds Average Navier-Stokes (URANS) equation is used to numerically solve the process of green water in time domain. The volume of fluid (VOF) method is used to capture the water surface and interface. The model investigated in this study is a modified Wigley ship. Numerical simulation conditions are set according to the experiments conducted in the towing tank at RIAM, Kyushu University. Ship loads and pressure measured at five monitoring points on the deck are compared with experimental data, while the ship motion is fixed in head waves. The numerical uncertainty of time steps and grid sizes is discussed in details. A set of simulation results with appropriate grid and time step are compared with the experimental data. Brief conclusions are given by analyzing the parameter time history, global hydrodynamic force, peak pressure values at gauges and green water process.
Real-Time Deterministic Prediction of Ship Motion Based on Multi-Layer LSTM
Authors: He Guolian , Dong Guohua , Yao Chaobang , Sun Xiaoshuai 
Published: September 2023

Abstract
Ship motion prediction is applied to the ship maneuvering to keep the motion attitude stable all the time, which is of great practical significance to the safety and efficiency of the sailing and shipboard equipment operation. However, ship motion is a complex time-varying nonlinear process, which varies with sailing conditions and environmental factors. Long short-term memory (LSTM) deep learning model provides a potential way for nonlinear ship motion prediction due to its powerful capability in nonlinearity processing. Determination of a reasonable dimension of the input vector and output vector is critical in training the LSTM model. The input vector represents the hidden time autocorrelation in random ship motion, and the output vector is used to evaluate the prediction performance. Therefore, a ship motion prediction synthesis method based on multi-layer LSTM model is proposed. In the Bohai Sea, China, the original motion data are obtained and used as the basis for analysis and demonstration. Inevitably, there is high-frequency noise interference and low-frequency certain trend in the measured data. Low pass filtering and empirical mode decomposition (EMD) methods are used to remove noise. Based on the multi-layer LSTM model, the ship motion data under different speed conditions are analyzed, and the optimal relationship between input vector and output vector is investigated. Numerical results show that this method can improve the prediction result, and realize the prediction function for 20 timestep. This research is of great practicability for ensuring the safety of navigation and improving the efficiency of maritime operations and the intellectualization level of ships.
CFRP-Based Strengthening of Perforated Tubular Members
Authors: Hernández Irving D. , Vaz Murilo A. , Cyrino Julio C. R. , Martinez Jorge L. , Torres Victor D. , Perrut Valber A. , De Paula Gustavo G. 
Published: September 2023

Abstract
Steel offshore tubular members corrode over their lifespan. If there is inadequate protection, corrosion might lead to a perforation. The bulk of the time, techniques for repairing perforations in tubular steel structures include welding operations, which raise the risk of accidents when large areas are involved. Alternative repair procedures based on composite materials are gaining popularity since they do not require heat sources. However, there have been few investigations on its mechanical performance, and there are no guidelines for dimensioning strengthening repairs. In this study, a carbon fiber patch is used to strengthen perforated steel tubular members. The mechanical properties of the repair composite material were determined experimentally. A series of experimental tests on 1:3 scale samples of flare-boom structures, with varying perforation levels, are carried out to investigate the strengthening performance. This study also evaluates the effectiveness of a numerical model proposed to predict the performance of perforated steel tubular members reinforced with CFRP laminate and to estimate the suitable patch size. The numerical and experimental results indicated that strengthened tubes retrieved substantially higher compressive force than unrepaired tubes, suggesting the feasibility of this strengthening procedure with lower risk and shorter implementation times.
A Problem of Long Period Yaw Motion of an Ultra-Large Floating Offshore Wind Turbine and its Reduction Countermeasure
Authors: Ota Makoto , Murai Motohiko , Otaka Isami , Kondo Shuto 
Published: September 2023

Abstract
In June 2022, the New Energy and Industrial Technology Development Organization (NEDO) of Japan created a 2 trillion yen “Green Innovation Fund” in June 2022. The fund will “develop technologies for wind turbines and floating structures that are suited to Asian weather and ocean conditions for floating wind turbines, which are expected to expand in the medium to long term, and demonstrate the integrated design of wind turbines, floating structures, cables, and other components with a cost level that can compete globally, leading to their social implementation”.
The demonstration of floating wind turbines in actual sea areas in Japan has been conducted off coast of Fukushima Prefecture, off coast of Goto in Nagasaki Prefecture, and in the Hibikinada Sea in Fukuoka Prefecture, where technological accumulation and investigation toward commercialization are being conducted.
While the rated power generation capacity of these demonstration wind turbines is 2–7 MW, the rated power generation capacity envisioned in the above-mentioned fund is 15 MW, and the specifications for the design of floating structures to accommodate ultra-large wind turbines have become more stringent.
As a new issue, it is a relative yaw motion between a nacelle and a tower. The characteristic of such yaw motion has a long period yaw motion, and it is relatively slower than pitch or heave motion but relatively faster as its nacelle tracking motion for catching the wind direction. The effects of reduction of yaw motion and yaw motion speed by a virtual propulsion system attached to the floating structure were qualitatively and quantitatively investigated as countermeasures against the yaw motion problem.
Application of STABLEpipe Method C Assessment to Determine On-Bottom Stability of a Cable Crossing in North Sea Mobile Seabed Conditions
Authors: Jorgensen Jack , Griffiths Terry , McGrath Nicholas , Görmüş Doğukan , Severs Glenn , Thurstan Bryan , Pistani Fabrizio , Ledoux Bart 
Published: September 2023

Abstract
The STABLEpipe JIP produced guidance for the on-bottom stability design of pipelines and cables on mobile or erodible seabeds. This paper describes the first known application of STABLEpipe Method C to assess behaviour of a cable with spatially varying properties (on-bottom weight, external dimensions etc.) to assess the on-bottom stability (OBS) of an offshore windfarm power export cable installed on a mobile seabed in the Dutch sector of the North Sea. The segment assessed is a pipe crossing, clad with a cable protection system (CPS) installed to provide mechanical separation between the cable and pre-existing seabed infrastructure (cable or pipeline). The seabed is sandy, and mobile under ambient conditions. The OBS analysis considers time-varying seabed embedment and seastate evolution to determine whether the crossing section deflects more than a set criteria of +/− 1 m. Field observations of the behaviour of the crossing section are compared to the numerical analysis, providing evidence that the predicted lateral displacements were not exceeded.
A Fast Numerical Model for Evaluating the Stability of a Damaged Ship in Regular Beam Waves
Authors: Duan Jianwen , Ma Ning , Shi Qiqi , Gu Xiechong 
Published: September 2023

Abstract
Damage stability in waves, which reveals highly non-linear and complicated behaviors, is attracting more and more attention recently. In this paper, a fast numerical model for predicting the stability of a damaged ship in regular beam waves is presented and validated by the published model experimental data. The potential flow theory is applied to build the basic model. In the basic model, the flowrate through the breach is calculated through modified Bernoulli’s equation. The compressibility of air and the phenomenon that air escapes from the air pocket in a bubble flow are simply simulated by modified Bernoulli’s equation for compressible fluids and nuclei number density distribution function respectively. The lump mass method is introduced to estimate the sloshing force of floodwater inside the damaged compartment and roll damping is obtained from roll decay experiment of damaged ship. Then the numerical model is applied to the International Towing Tank Conference (ITTC) benchmark model in still water and the frigate hull named DTMB5415 in regular beam waves. Internal water height in the damaged compartment, roll decay of the damaged hull and motion responses in regular waves are calculated and compared with available model experimental data. It is confirmed that the results of the numerical model have a good agreement with the published experimental data.
Modelling of Fibre Rope Mooring for a Floating Offshore Wind Turbine
Authors: Viuff Thomas , Sørum Stian H. , Kvittem Marit I. 
Published: September 2023

Abstract
Synthetic fibre rope materials such as polyester and nylon are used frequently in the offshore industry due to their low weight and flexible properties. A drawback when utilizing these synthetic fibre rope materials is how to account for their complex, non-linear tension-stretch behaviour, which is a combination of both instant-elastic, visco-elastic, instant-plastic, and visco-plastic (creep) material behaviour. This complex behaviour has previously been simplified as a linear stiffness based on an upper bound or lower bound criterion when performing time domain analyses. These stiffness bounds are based on design tension and platform offset criteria. Today it is recommended to use a bi-linear stiffness curve to include both criteria in one, although the model is still a crude approximation of the real behaviour. Recently, the Syrope JIP has developed a method to account for the non-linear behaviour more accurately, which depends on the mean tension, the load rate, and the load history. This Syrope model is utilized in the present study for mooring system design analyses of a floating offshore wind turbine (FOWT) concept and compared to the previously mentioned methods applied in the industry today. The comparison encompasses both fundamental static and dynamic properties of the concept, as well as design tension based on ultimate limit state (ULS) conditions.
A Simple Estimation Method for Ultimate Strength of Curved Plates Under Axial Compression
Authors: Shiomitsu Daisuke , Ishibashi Kinya , Yanagimoto Fuminori , Fujikubo Masahiko 
Published: September 2023

Abstract
A simple estimation method for ultimate strength of curved plates under axial compression is proposed. Existing estimation methods are mostly empirical based on plastic correction of elastic buckling strength or curve fitting the results of test or nonlinear finite element analysis (NLFEA). For more rational design, it is important to develop a method having more theoretical basis in accordance with physical phenomena including post-buckling behavior, yielding behavior, and effects of initial imperfections and material properties as well as the elastic buckling strength. A series of NLFEA is performed to investigate the buckling and collapse behavior of curved plates under axial compression. Using identified buckling modes and applying the elastic large deflection theory, elastic post-buckling behavior is formulated. The ultimate strength is estimated by checking yielding at specified locations depending on the collapse modes. The proposed method gives the ultimate strength without any iterative calculations. The applicability of the proposed method is demonstrated though a comparison with NLFEA results.
Bayesian Network Modelling of Aero-Mechanical Performance of Wind Turbine
Authors: Dao My Ha , Le Quang Tuyen , Zhao Xiang , Ooi Chin Chun , Luu Trung Pham Duong , Raghavan Nagarajan 
Published: September 2023

Abstract
In this paper, we demonstrate a Bayesian Network (BN) model that returns indicators in terms of range of values and likelihoods of occurrence from the inputs of operating conditions, i.e. inflow wind speed, rotating speed, tilt and pitch angles. The BN could also be used to derive operating conditions (i.e. rotation speed or pitch angle of blade) that maximize the possibility of achieving a desired power output while subject to certain turbine structural conditions.
The BN model is built from a large database of high-fidelity CFD/FEA simulations of a 5MW NREL wind turbine. The abnormality is assumed to be in the form of abnormal deformation and/or stress that are numerically generated by introducing corresponding faults in the blade structure. The database generation, construction and demonstration of the BN model will be presented in the paper.
Design Assessment and Optimization of a Barrier Valve for Subsea Applications
Authors: Ahmadli Mehman , Gjersvik Tor Berge , Sangesland Sigbjørn 
Published: September 2023

Abstract
A subsea Christmas tree is an integral part of the barrier system allowing the controlled production of hydrocarbons while serving to shut in the production in case of an emergency or a need for a planned shut-down. The most important components of the Christmas tree are the barrier valves, most often remotely hydraulically operated, spring-loaded, and fail-safe gate valves.
A primary or wing barrier valve is subjected to full wellhead shut-in pressure when closed. To open such a valve, the valve needs to be forced towards opening overcoming high friction and spring preload forces until the valve opens allowing flow to start and pressure to equalize across the valve. With the coming change to all-electric control systems (AES) dispensing with hydraulics for actuation, it would be highly beneficial to the controls design and power requirements if the operational forces and power required for valve actuation could be reduced.
This paper investigates the possibilities of force and power reduction through the following ways: alternative lower friction coating material and geometrical change of the valve parts. As an alternative coating material polycrystalline diamond compacts (PDC) are analyzed. By geometrical change, we seek a solution whereby only a shorter stem displacement is required before the crack-opening and after the crack-closing phase. The valve is 3D modeled using the same subsea conditions, the model is analyzed using finite element methods.
Energy-Efficient Marine Engine and Dynamic Wing Evaluation Under Laboratory Conditions to Achieve Emission Reduction Targets in Shipping
Authors: Perera Lokukaluge Prasad , Belibassakis Kostas 
Published: September 2023

Abstract
There is a requirement to comply with the forthcoming IMO & EU requirements to reduce ship emissions by at least 40% in 2030 compared to the 2008 levels. Such medium-term emission reduction targets can only be achieved by introducing novel technologies into the shipping industry. The SeaTech H2020 project (seatech2020.eu) introduces two main innovations that can support the same emission reduction objectives. Those innovations consist of integrating an energy-efficient marine combustion engine with a renewable energy recovery device, i.e. dynamic wing. However, these two technologies are not evaluated in an actual environment in a selected ocean-going vessel. On the other hand, various data sets are collected from both innovations and can be used to quantify their energy efficiencies in a data science environment. Furthermore, it is expected that both innovations should interact with each other in the same data science environment as well as in the respective testing platforms, therefore more realistic vessel operational conditions can be introduced. Hence, this study introduces realistic head wave conditions in both innovations, where the dynamic wing creates adequate thrust to push the vessel forward under the same ocean wave conditions. The same thrust and ocean wave conditions have been applied to marine engine testing as the main contribution of this study. Finally, the data sets collected from the engine testing platform under its loading situations for both wave and thrust conditions of the selected ocean-going vessel are presented in this study.