bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Study on Dimensionality Reduction Technique-Based Wave Estimation Using the Motion Response Spectra of the Advancing Ship
Authors: Ko Donghyeong , Nam Bo Woo , Choi Ju Hyuck 
Published: August 2024

Abstract
This study introduces a new hybrid method, named the two-step method, for estimating the wave spectrum of an advancing ship. Among the various wave estimation approaches based on the wave-buoy analogy, the two-step method, rooted in the brute force algorithm, utilizes parametric main wave heading direction and spreading strength. The method follows a stepwise approach, initially detecting the wave heading and subsequently estimating wave height and period based on the pre-detected wave heading direction. In the first step, pseudo data is generated through numerical simulation and combined with real motion data to create a high-dimensional feature space. The feature values extracted from the motion response spectra demonstrate distinct characteristics, where the magnitudes vary gradually with changes in wave direction as the wave heading develops, influenced by forward speed and hull form. Utilizing the nonlinear dimensionality reduction technique t-SNE, these feature values facilitate the visualization of wave heading clustering levels in the dataset. Additionally, the graph-based semi-supervised learning algorithm, label propagation, is employed to estimate the wave heading using simulation data. In the second step, wave height and period are estimated using the modified brute force algorithm based on the pre-detected wave heading. The accuracy of the proposed method was validated by comparing it with model test results, demonstrating enhanced performance compared to the original approach. It is expected that the proposed method could efficiently detect the wave spectrum and the main wave heading.
Calculation of Force-Coefficients of a Wind Propulsion System for a 4 DOF Velocity / Power Prediction Program
Authors: Oettle Johannes , Krüger Stefan 
Published: August 2024

Abstract
In this paper, a method to calculate the force coefficients of a wind propulsion system consisting of single wind propulsion elements is presented. With this method it is possible to calculate the forces of the whole system using measured or calculated force coefficients of single elements, without knowledge of the section shape of the wind propulsion elements. The single elements are modelled as horseshoe vortices to calculate the interaction inbetween the elements. This method is based on potential theory in order to quickly obtain sufficiently accurate force coefficients, which are necessary for velocity respectively power prediction programs. These programs balances the forces acting on the ship to evaluate the performance of the wind ship or wind assisted ship in an early design stage. Calculations of wind propulsion systems consisting of five and six curved rectangular plates are presented and compared with wind tunnel measurements. These calculations demonstrate adequate accuracy, particularly in the domain of small angles of attack, which is of interest for wind-assisted ships.
An Optimal Adaptive Bias RBF Controller for Dynamic Positioning Vessels
Authors: Ye Yutu , Wang Yiting , Wang Lei 
Published: August 2024

Abstract
To improve the performance of tracking control for dynamically positioned (DP) vessels, this paper presents the design and implementation of an adaptive robust backstepping controller without using model parameters in the presence of unknown time-varying disturbances. The bias radial basis function neural networks (RBFNN) are employed to compensate for the uncertainties and disturbances of ship dynamics. The introduction of bias term of RBFNN helps to avoid the designing of additional integrator of backstepping. The output of the RBFNN can be non-zero when the inputs of the RBFNN deviate significantly from the center points because of the bias term, which improves the robustness of the adaptive RBFNN controller. The reference trajectories of this paper are generated by linear quadratic regulator (LQR) to diminish the overshoot and save the energy consumption. The system matrices used in LQR are identified through the data-driven technique. Uniform boundedness of the closed-loop system is proved by the Lyapunov stability theory. Simulation results illustrates the performance of suggested control scheme.
Towards Integrated Asset Modelling With Intermittent Green Power
Authors: Roli Ole-André , Skogestad Jan Ole , Persia Cosimo , Nybø Roar , Schümann Heiner , Bergmo Per Eirik Strand 
Published: August 2024

Abstract
The introduction of offshore wind turbines and shore-based electrification on the Norwegian Continental Shelf is a source of green energy, replacing gas-powered turbines. However, while the phase-out of offshore gas turbines will reduce CO2 emissions from offshore installations, the fluctuating electricity price and availability of wind power pose challenges for the oil and gas production on the installations. In the framework of Integrated Asset Modelling (IAM), we are studying how higher flexibility in the energy demand of the production system can alleviate this issue and reduce CO2 emissions without affecting production adversely. In this paper we give an overview of findings and challenges in applying IAM to CO2 emissions and work on cloud solutions that can help facilitate dissemination and uptake of research findings in the oil and gas industry.
A Novel Approach of Data Science Incorporating Physical Knowledge for Early Stuck Pipe Detection
Authors: Inoue Tomoya , Kaneko Tatsuya , Nakagawa Yujin , Wada Ryota , Abe Shungo , Yasutake Gota 
Published: August 2024

Abstract
Early detection of stuck pipes during drilling operations is crucial and challenging. Some of the existing studies on the stuck pipe detection have adopted supervised machine learning approaches that employ datasets for “stuck” and “normal”. However, for early detection before the occurrence of stuck pipe, the application of ordinal binary classification in supervised machine learning has presented several elemental concerns, such as limited stuck pipe data, and lack of an exact “stuck sign” before occurrence. Our previous studies proposed unsupervised machine learning approaches using data on the normal activities with long short-term memories and autoencoder, the mixture probability model, and graph attention model, and presented the possibility of predicting a stuck pipe. On the other hand, there observed false positives responding the operation of drilling equipment or changes in drilling data.
We introduce a data science approach, including machine learning, incorporating physical knowledge to overcome frequent false positives. This study initially introduces the stuck pipe predictions using unsupervised machine learning approaches, and a typical false positive case. Subsequently, we present machine learning integrating physical knowledge and demonstrate early stuck pipe detection using field data containing stuck pipe events. The results show significant suppression of false positives. Our machine learning approach is expected to contribute to considerable reduction of nonproductive time in drilling operations, potentially preventing well abandonment.
Influence of Configuration of Hemispherical Artificial Reefs on Scouring Around Offshore Wind Power Pile Foundation
Authors: Han Shuwei , Li Dawei , Yang Mingda , Tang Yanli , Zhao Fenfang , Huang Liuyi 
Published: August 2024

Abstract
The burgeoning integration of offshore wind power and marine ranching underscores a pivotal avenue for the harmonized advancement of marine fisheries and sustainable energy. Central to this integration is the strategic deployment of artificial reefs (ARs), especially for mitigating scour around offshore wind power pile foundation (OWF). This study pioneers a three-dimensional numerical model, leveraging the prototype of China’s first offshore wind power-marine ranch demonstration project. Employing the Reynolds-averaged Navier-Stokes equations and sediment transport dynamics, the model intricately simulates fluid motion and sediment scour in the proximity of ARs and OWFs.
The numerical results indicate that the proximity between a single hemispherical AR and OWF significantly dictates scour severity, with closer ARs (G/D &lt; 2) exacerbating scour due to underdeveloped wake regions and increased turbulence. Conversely, at greater distances (G/D ratios of 2 and 3), ARs fully develop protective wake regions, effectively reducing scour depth by 37% and scour volume by 42% around the OWF. The study further reveals that specific arrangements of ARs can either mitigate or intensify scour effects. While parallel configurations of ARs demonstrate a notable reduction in scour depth and volume, this protective efficacy wanes with increasing P/L ratios, ceasing beyond a P/L ratio of 4. In contrast, a tandem arrangement of ARs, especially at a G/D ratio of 1, sharply intensifies scour volume around OWF. The findings are instrumental in guiding the design and arrangement of ARs in marine environments, aiming to enhance the structural stability of OWFs and contribute to the ecological harmony of marine systems.
Undrained Load-Carrying Capacity of Subsea Foldable Mudmat Foundations Under General V-H-M Loading
Authors: Feng Xiaowei , Li Xiaolong , Sun Liqiang 
Published: August 2024

Abstract
With offshore oil and gas developments moving into deep water, the size of mudmats foundations has been increasingly large, exceeding the handling capacity of the installation vessels. The foldable design can effectively avoid the constraints by the stinger or the moon pool. The analytical and numerical solutions of the undrained load-carrying capacity of shallow foundations are mostly available for single (isolated) foundations, and not feasible for design of the foldable mudmats. The undrained bearing capacity and failure mechanisms of the foldable mudmats depend significantly on the foundation spacing and the soil strength profiles. Finite-element simulations are carried out to determine the undrained load-carrying capacity of the foldable mudmats under general loading. Results are presented in the form of failure envelopes under combined V-H, V-M, H-M and V-H-M loading. The load-sharing mechanisms of two rigidly connected mudmats are investigated. Soil failure mechanisms are illustrated for the representative loading paths of the foldable mudmats, and their dependency on the foundation spacing and the soil strength heterogeneity is systematically examined. Based on the revealed failure mechanisms, the methods are established for predicting the undrained load-carrying capacity of the foldable mudmats. Comparisons of the predictions with the FE results indicate that the proposed method is highly credible to assist the foundation design in practice.
Hydrodynamic Performance of a Pitching Circular Motion Hydrofoil for Tidal Current Energy Harvest
Authors: Yao Huilan , Zhang Boxiao , Zhou Xin 
Published: August 2024

Abstract
Considering that if a pitching hydrofoil moves in a circle, the mechanical structure of the turbine can be further simplified, which is much simpler than a traditional oscillating hydrofoil tidal current turbine, therefore the performance of a pitching hydrofoil with such simple trajectory has attracted our interest. In this paper, numerical method was adopted to simulate a pitching circular motion hydrofoil with variety of motion parameters. Before that, the method was verified and validated. Then, instantaneous hydrodynamic forces, vortex flow field and power coefficients of the hydrofoil were studied. More importantly, the effect of pitch amplitude and circular motion frequency was investigated. Results show that, the vertical force (lift) is the main power for the hydrofoil to harvest energy. For most of the time in one motion period, the horizontal force and pitch moment do negative work. The favorable interaction between vortex and hydrofoil can increase the positive work done by the lift and reduce the negative work done by horizontal force and pitch moment, thus improving the energy harvest efficiency. There are optimal values for the two main motion parameters, which can maximize the energy harvest efficiency. When the pitch amplitude is 75 degrees and the reduced frequency is 0.14, the efficiency can reach more than 40%.
Suppression of Vortex Shedding Past a Cylinder at Higher Reynolds Numbers: A Numerical Study
Authors: Parida Aniket , Srineash V. K. , Behera Manasa Ranjan 
Published: August 2024

Abstract
Vortex-induced vibrations (VIV) are induced on a bluff body when it is introduced to a fluid flow, which produces vortex shedding. Many times, the presence of VIV attributed due to vortex shedding is considered undesirable since it leads to fatigue induced damage on structural elements. The phenomenon of VIV is an important consideration, especially for offshore structures which are usually made of cylindrical members. The present study investigates the suppression of vortex shedding past a fixed cylinder using streamlined fairings and short-tailed fairings using a Computational Fluid Dynamics (CFD) solver based on Reynolds Averaged Navier-Stokes (RANS) equation. Fairings are relatively neutrally buoyant elements that are installed along the axis of long circular cylinders in order to lower drag force and to minimize VIV. The work aims at studying the vortex shedding pattern of a bare cylinder, cylinder with streamlined fairings and cylinder with short-tail fairing for various flow conditions. The hydrodynamic coefficients (e.g., lift coefficients, drag coefficients), and Strouhal number are key parameters that govern the vortex-induced vibration (VIV) on the cylindrical members. Therefore, the study would also entail investigations on hydrodynamic lift and drag forces/coefficients. The range of Reynolds Numbers covered in the studies will be 1*103 &lt; Re &lt; 50*103. The study examines the influence of streamlined fairing and short-tail fairing in altering the vortex shedding behavior. The outcomes based on the study would help to understand the reduction in vortex shedding due to use of streamlined fairings in place of a fixed cylinder. This in turn would help in better design of offshore structures avoiding impacts due to VIV.
Flow-Induced Vibration of Flexible Hydrofoil in Cavitating Turbulent Flow
Authors: Cheng Zhi , Jaiman Rajeev 
Published: August 2024

Abstract
The flow-induced vibration and cavitation dynamics of three-dimensional flow past a cantilever flexible hydrofoil are investigated using a large eddy simulation (LES) model, a homogeneous mixture cavitation model and the structural modes superposition method. The present work aims to explore a potential mechanism responsible for a propeller singing behavior, and thus focuses on the synchronized hydroelastic coupling among the pressure pulsation inside the flow field, the cavitation generation and the structural vibration. To begin, we validate the tip vortex dynamics of a flexible hydrofoil against the available experimental. Our results demonstrate that the tip vortex shedding and the blade vibration are responsible for the intense peak in the low-frequency tonal components of the noise source, and the trailing-edge vortex shedding induces broadband components. Additionally, the generation of sheet cavitation induces considerable synchronized hydrofoil vibration (subjected to a flutter-like response), and affects the pressure fluctuations in the flow field, which further dominate the features of the underwater noise sources. It is suggested that the cavitation behavior and structural vibrations co-dominate the characteristics of singing noise from a propeller blade.
Hydrodynamic Response of Semi-Submersible Platform of Floating Offshore Wind Turbine Under Extreme Waves
Authors: Cui Ting , He Guanghua , Wang Widar Weizhi , Yuan Lihao , Bihs Hans 
Published: August 2024

Abstract
Offshore wind turbine play a key role in the renewable energy strategy due to the advantage like the faster wind speed in offshore area and higher power generation reliability. As the development of offshore wind turbine (OWT) from near coastal area to the deep sea, floating type foundation is the inevitable direction for OWT. The hydrodynamic performance analysis of floating offshore wind turbine (FOWT) is required under different marine conditions to improve the structure safety and stability and ensure the power generation efficiency. However, the study of extreme wave condition interaction with FOWT, like tsunami waves, incidental rogue wave etc., remains a difficult scientific research challenge. In this paper, the hydrodynamic performance of Semi-submersible platform of FOWT is modeled and analyzed under extreme waves using Hydrodynamic-Coupling (HDC) method. HDC is a coupling method between the fully nonlinear potential flow (FNPF) solver and Computational fluid dynamics (CFD) solver within the open-source hydrodynamics framework REEF3D. This method satisfied the computational efficiency and high fidelity of the simulation of extreme wave events by using FNPF to provide far-field wave generation and propagation information and adopting CFD to calculate the near fluid field physical characteristics and impact details required when modeling the process of extreme state. The dynamic responses including surge and heave motion of a semi-submersible under extreme wave are carried out under typical extreme wave conditions. The numerical model is validated against experiments of rogue waves interaction with a semi-submersible platform. The HDC method achieved a computational efficiency of the same wave condition.
Experimental Study on the Wave Run-Up Properties and Slamming Loads of a Four-Column Floating Wind Turbine System
Authors: Zhou Yan , Deng Shi , Zhong Wenjun , Wang Jingkai , Fu Shenglei 
Published: August 2024

Abstract
China Offshore Oil Engineering Cooperation (COOEC) has constructed a semisubmersible floating wind turbine system in South China Sea. It is designed to withstand extreme sea state, horizon cyclone with a return period in 50 years. In addition to conventional design criteria, maximum inclination and acceleration, wave run-up and slamming loads also challenge the safety operation and integrity of the structure. A scaling mode test was conducted for these nonlinear-hydrodynamic domain issues. Wave run-up phenomenon is categorized into three groups based on the test observation, namely, climb-up, white water and green water. The climb-up is accepted in design due to its low load level and water entry. The white water could be tolerated if the structure withstands slamming loads, while the green water must be prevented due to its unexpected large loads. For the evaluation of slamming loads, a numerical method is proposed based on calibration result. The wave surface elevation near the platform is calibrated using the test result, and then the water particle velocity is determined by partial differentiation of the free surface boundary condition. The slamming pressure is consequently obtained using conventional formulas and empirical coefficients. The proposed wave run-up design procedure and slamming loads calculation method provide a basic reference for floating wind turbine design allowing for a smaller margin compared to widely accepted methods used in offshore oil and gas projects.
Numerical Calculation Method for Vibration and Sound Radiation of a Flat Plate Under Turbulent Boundary Layer Excitation
Authors: Huang Zhangkai , Dong Wenkai , Chen Meixia , Wang Ting 
Published: August 2024

Abstract
Structural vibration and noise excited by turbulent boundary layer are the main noise sources for underwater vehicles. The vibration and noise of flow-excited structures are usually solved by analytical and numerical methods, and the numerical method is widely studied because of its applicability to complex structures. In this paper, the analytical and numerical methods are analyzed for the vibration response of finite and infinite plate excited by turbulent boundary layer. Aiming at the deviation of the numerical method, a correction formulation for the numerical results is proposed from the discrete point of view of the numerical method. The results show that the numerical results after correction match well with the analytical results. The effects of different parameters on the correction are investigated, and the difference in the correction in different fluid media is analyzed. The correction formulation still works effectively for structures in water. This study provides valuable insights for the rapid prediction of structural vibration and noise excited by turbulent boundary layer.
A Statistical Probability Model for Underwater Object Detection From Sonar Images
Authors: Song Lifei , Tan Yan Zhi , Goh Eng Wei , Ang Marcelo H. 
Published: August 2024

Abstract
Detection of underwater structures using a multi-beam forward looking sonar poses significant challenges due to various factors such as sonar noise and multi-path acoustic reflections. In this context, machine learning techniques have proven to be valuable tools. However, they require a substantial dataset of real sonar samples to effectively train the network for structural object detection from sonar images. Notably, even untrained structures or structures that closely resemble one another may fail to be correctly detected by the network. To address this, we propose an innovative algorithm that combines computer vision and statistical probability models for the detection of underwater structures. Our proposed algorithm begins by employing OTSU and connected component labeling and analysis to identify potential regions of interest within individual single-frame sonar images. It then takes advantage of the spatial continuity present across multiple consecutive frames to pinpoint key structural areas in each frame. A probability model based on the Kalman filter is applied to precisely delineate the contours of the structure within each frame. The objective of this process is to reliably generate the edges of underwater structures from sonar images. The effectiveness and reliability of this algorithm are demonstrated through rigorous real-world sea trials conducted at a pier, further emphasizing its practical applicability and suitability for addressing the complexities of underwater structural detection.
Numerical Investigation on the Hydrodynamic Characteristics in the Tank of Aquaculture Vessel
Authors: Sun Zhiyong , Li Hui , Miao Heyun 
Published: August 2024

Abstract
At present, deep-sea aquaculture faces numerous challenges, encompassing issues such as water body eutrophication, fish lice diseases, and adverse sea conditions that cause damage to aquaculture equipment. In response to these challenges, a mobile aquaculture vessel equipped with recirculating aquaculture systems has emerged as a preferred solution. These systems demonstrate precise water control capabilities, ensuring optimal aquaculture water quality and mitigating the occurrence of fish diseases. In contrast to deep-sea aquaculture cages, the hull structure of aquaculture vessels exhibits superior resilience to extreme sea conditions, thereby ensuring the safety of aquaculture operations. The hydrodynamic characteristics of aquaculture tanks play a pivotal role in the growth and health of fish. The aquaculture vessel, representing an emerging innovation, currently lacks a robust foundation of hydrodynamic knowledge to effectively support aquaculture production. In this paper hydrodynamic characteristics of aquaculture tanks are investigated based on the computational fluid dynamics (CFD) method, focusing on param such as flow velocity, vortices, and flow field uniformity. The analysis reveals the existence of low flow velocity zones and dead zones in the near-corner wall region of the octagonal aquaculture tank. In the region above water depth = −3 m, a noticeable velocity gradient and lower uniformity are observed. Notably, an increase in inlet flow velocity results in an improvement in the flow field uniformity in this region.