bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Method to Establish Characteristic Load Effect and Capacity Check During Installation Design for Marine Operations
Authors: Gullaksen Joannes 
Published: August 2024

Abstract
This paper will present a methodology for establishing characteristic load effect and capacity check while performing installation design as part of the modelling and analysis scope of marine operation in order to establish operational parameters and limit weather criteria. The purpose of installation design is to ensure safety in terms of personnel, equipment and environment, as well as the structural integrity of the product during installation. This is achieved by analyzing the different steps of an operation in order to establish operating parameters and limit weather conditions based on a comparison of extreme and characteristic load effects and relevant limit state criteria. The methodology is customized for product design codes that require products to be verified with respect to applicable installation loads, including design formats for capacity check for combined loads on rigid pipe, umbilical and power cables, as well as capacity check for single response quantities for flexible pipes directly from the time domain analyses. The extreme value is modelled with a probability distribution of the largest response, where the extreme value is a given percentile in the extreme response distribution. The Gumbel distribution is used as a model for the extreme value distribution to fit the largest response from each simulation realization. Alternatively, a more efficient procedure may be used, including establishing response time series, establishing time series for the load effect, fitting a 3-parameter Weibull distribution of individual maxima, establishing the associated Gumbel extreme value distribution for the largest individual maxima, and finally estimating extreme value as the appropriate percentile in the Gumbel distribution. The method is implemented in a software application to be able to automate the process and which can also be used as a postprocessing tool along with a non-linear time domain analysis solver. Nonlinear time domain analysis is required to handle nonlinearities in geometric stiffness, hydrodynamic loading, material nonlinearities and contact problems. Nonlinear properties and hydrodynamic load mechanism are transforming the wave frequency of Gaussian excitation into non-Gaussian global responses. Assessment of extreme load effect for non-Gaussian response processes is required to perform capacity checks based on an irregular wave representation. In present context, the meteorological and oceanographic data analysis involves manipulating, transforming, and visualizing data based on data analysis results using descriptive and inferential statistics.
Assessment of the Technical Potential of the Ocean Thermal Energy Conversion in the Brazilian Equatorial Margin
Authors: Corrêa Daniela , Shadman Milad , Almeida Jeferson , Estefen Segen Farid 
Published: August 2024

Abstract
This study investigates the potential of the Ocean Thermal Energy Conversion (OTEC) technology in the Potiguar Basin, that is part of the Equatorial Margin of the Brazilian coastline. OTEC is based on the Rankine thermodynamic cycle, which uses the temperature difference between the ocean’s surface and deep waters to generate electricity. The methodology employed in this study is based on the development of computer algorithms for processing temperature results from a three-dimensional global numerical model. Data in situ from Argo was used to correlate with HYCOM, validating the model to analyze ocean temperature. The temperature measurements from HYCOM are acquired in the research area considering 40 vertical layers (with a maximum depth of up to 6366 meters), with a daily temporal resolution between January 1, 2000, and December 31, 2020. The installation of an OTEC plant requires the presence of a thermal gradient of at least 20°C. This operational threshold was highlighted and considered in the context of this research. Calculations of gross and net energy power were done to analyze the warm-water and cold-water flow rates necessary for available energy. The technical potential of the OTEC is addressed considering the Pitu Oeste, that is an exploratory area from Potiguar, showing the possibility of decarbonizing the oil and gas activities.
A Response Frequency Informed LSTM Model for Ultra-Short-Term Mooring Line Forces Prediction of Floating Wind Turbines
Authors: Chen Peng , Kang Yirou , Zhang Ruihan , Cheng Zhengshun , Deng Shi , Erfort Gareth , Hu Zhiqiang 
Published: August 2024

Abstract
Accurate dynamic response forecasting is pivotal for operational monitoring, maintenance, and dynamic control of floating wind turbines (FWT), ensuring both efficiency and safety in real-world applications. This paper conducts the measured validation and application of the ultra-short-term forecast of a full-scale FWT’s mooring line tension by recurrent neural networks with the frequency decomposition method (RNN-FD). The RNN-FD method is one of the modules of our in-house program DARwind-AI to realize real-time or ultra-short-term forecasting of dynamic response of FWT. Initially, the principles of the RNN-FD method are introduced, including the Long Short-Term Memory (LSTM) encoder-decoder network, wavelet transform applicaiton and frequency decomposition method was demonstrated. Then, the validation of RNN-FD method is carried out using measured data from Hywind Scotland and the results of RNN-FD are promising, with a good agreement observed datasets from 2018 January to July. For instance, the Mean Squared Error (MSE), Mean Absolute Error (MAE), Mean Absolute Percentage Error (MAPE), and One-Nth Largest Error (ONLE) for mooring line forces forecasting at lead times of 60 seconds are 0.0065, 0.063, 0.034 and 0.073, respectively. Conclusively, this innovative methodology, rooted in both traditional engineering principles and artificial intelligence technology, offers promising prospects for real-time FWT monitoring and dynamic control.
Relative Motion Prediction for Integrated Floating Offshore Wind Turbine Installation Scheme Based on Data-Driven
Authors: Ma Can , Zhang Taiyu , Yang Zongyuan , An Yang , Zheng Xiang Yuan , Ren Zhengru 
Published: August 2024

Abstract
With the development of offshore wind power toward deeper seas, innovative installation methods for floating offshore wind turbines (FOWTs) are urgently needed. A novel installation approach involves a specially designed catamaran that carries multiple preassemblies (tower, hub, and blades are mated onshore) to the installation site. The approach separates the construction of foundations and preassembled upper structures. Carrying multiple preassemblies onboard shortens the transportation time, and only one lifting operation shortens the offshore mating time. Due to the complexity of the offshore environment, irregular relative motions occur between the preassemblies and the floating foundation. Larger relative distances between the mating points (lifted preassembly bottom center point and floating foundation top center point) would increase the outcrossing rate during the mating operation. Artificial neural networks are applied to predict the maximum and minimum relative motions between the two mating points during the implementation of mating operations. The installation scheme is simulated in various sea states using Sima, generating datasets for analysis. Statistical motion data (mean value and low-order central moments) for the past period are used as inputs to the neural network to obtain the maximum and minimum relative motion for the coming period. Simulation results show that the prediction model constructed by the back propagation neural network can predict maximum and minimum values of relative motions with acceptable accuracy. The proposed algorithm enables the prediction of potential hazards during the mating operation of the conceptual installation method, facilitating informed decision-making by the crews.
Nonlinear Dynamic Analysis of 2-D Jacket Structure Considering Joint Nonlinearity
Authors: Kumar Ram , Kumar Deepak , Paul Bapon 
Published: August 2024

Abstract
Jacket structures are recognized for their fixed-base design and inherent structural stiffness among the most critical offshore engineering structures. This rigidity, stemming from their solid connection to the foundation, results in a slightly shorter natural time period than their floating structures. Comprising a framework of interconnected tubular members with rigid connections, jacket structures offer durability and stability in the challenging offshore environment. However, the operational performance of these jacket structures is significantly influenced by dynamic forces arising from the random ocean environment. The interaction between the random ocean dynamics and the structural integrity of jacket structures can lead to joint rotations and deformations, introducing nonlinearity into the system. The extent of joint nonlinearity is a critical factor that can intensely affect these offshore structures’ dynamic responses. This comprehensive study extends its focus to involve complete 2D jacket structures by using Finite Element Analysis (FEA) software ABAQUS to model joint behaviour and understand the details of nonlinear dynamic behaviour. The joint modeling approach not only considers the influence of varying angles between members but also accounts for joint level buckling under varying external loading conditions. In the presence of joint buckling, the nonlinear behaviour of the jacket structure changes significantly. This becomes more significant because it may cause significant fatigue damage to the structural joints. The study is focused on understanding the joint buckling and its nature under random ocean waves for a 2D jacket structure. Further, the effect of buckling on the nature of response is studied. This research enhances our understanding of the interaction between structural nonlinear elements (under joint buckling) and dynamic forces, ultimately offering essential information for offshore engineering design, assessment, and safety.
The Effect of Side Girder Distance in Bottom Structure to the Ultimate Strength on Double Hull Tanker
Authors: Muis Alie Muhammad Zubair , Juswan  , Rachman Taufiqur , Mustafa Wahyuddin , Alamsyah  , Rahmadani Elsa Fitria 
Published: August 2024

Abstract
Double bottom structure consists of many elements such as bottom and inner bottom longitudinal, center and side girders, solid and watertight floors and so on. Those elements have dimensions and must be located according to specified distance. The effect of distance has contribution to the deflection or deformation in the local area especially on double bottom. The intersection between longitudinal and transversal elements also gives effect. Therefore, the distance from each installed construction element must be considered more carefully.
The objective of the present study is to analyze the ultimate strength caused by the influence of the side girder distance on double bottom of Double Hull Tanker (DHT) for existing and after changing the distance of side girder. The double bottom caused by changing the distance of side girders is analyzed to the ultimate strength of DHT hull girder under hogging and sagging. The analytical method is adopted to analyze the DHT due to the effect of side girder distance to the global structure.
The ultimate strength obtained by analytical method is compared between existing condition and after changing the side girder distance on double bottom. The ultimate strength in terms of the moment-curvature relationship including their behavior is presented in this study.
Structural Response of a Container Ship Against Beam Sea Wave
Authors: Yanagimoto Fuminori , Ishibashi Kinya 
Published: August 2024

Abstract
This study carried out nonlinear finite element analyses of an imaginary container vessel under beam sea wave conditions. Deformation and collapse behaviors of hull structures have been studied using finite element analysis, but many of them focused on the behavior under following and heading wave conditions, evaluating hull girder ultimate strength. Although recent requirements to assess hull structure strength employ beams sea wave, in addition to longitudinal wave, the structural response against beam sea wave has not been paid attention to. In particular, the transverse structures such as side transverse and side shell are supposed to be influenced by the beam wave conditions, but detail analyses of their deformation affected by yielding and buckling have been rarely conducted. A series of nonlinear finite element analyses using a so-called three-hold model of mid region of the container ship were carried out by applying the wave pressure, cargo load and inertia due to ship acceleration, and hull girder moment supposing the time of the maximum roll angle. The results reveal that the side shell undergoes elastic buckling, but the further deflection is suppressed by the neighboring intact side transverse because the compressive displacement of short sides of the side shell panels are constrained by the side transverse. Such behaviors were observed in analyses with different thickness of the side shell and side transverse. Such ‘surrounding’ structure effect might contribute to the hull structural integrity under beam sea waves.
Maneuvering Stability Analysis of a Fouling Autonomous Underwater Vehicle in Horizontal Plane
Authors: Zhang Xiaohui , Huo Jianlong , Xu Qimao , Zhang Meng 
Published: August 2024

Abstract
During the operation of a submerged submarine, its surface will inevitably suffer from fouling, which will affect its hydrodynamic performance. In this paper, the horizontal maneuvering stability of the rough submerged submarine is studied based on the RANS method, where the Defense Advanced Research Projects Agency (DARPA) SUBOFF model developed by the David Taylor Research Centre (DTRC) is taken as the object hull. An appropriate roughness function model proposed by Demirel et al. (2017) for a range of representative coating and fouling conditions is selected to describe the roughness conditions. The hydrodynamics of the smooth SUBOFF model in infinite depth and wide area are calculated, and the validity of the numerical results is verified by the results of the tank test. The hydrodynamic coefficients of translation and rotation of the rough SUBOFF are obtained through the oblique towing tests and the pure yaw tests. According to Routh’s stability criterion, the horizontal maneuvering stability index of rough SUBOFF is obtained. Subsequently, the impact of the roughness height and the distribution position on the horizontal maneuvering stability is analyzed. The results show that when the surface of the submarine is partially covered with deteriorated coating or light slime, the stability index in the horizontal plane decreases by 31.70% for the case of stern one-third of the area fouled only, which is more hazardous than the case of forward one-third of area fouled only (6.23% decrease) or the case of middle one-third of the area fouled only (4.02% decrease). Therefore, minimizing the roughness attached to the stern surface is very beneficial in maintaining the stability of submarines.
Mooring Line Tensions Prediction Based on MLP for Soft Yoke Mooring System
Authors: Li Ying , Zhong Qiyuan , Gan Qiang 
Published: August 2024

Abstract
The soft yoke mooring system is widely used for the floating production storage and offloading (FPSO) in shallow water. However, there were accidents of mooring system being pulled down by the FPSO in field. It is hence necessary to conduct realtime prediction of mooring line tensions. Under complex environmental loads, the coupled effects of the mooring system and floaters lead to nonlinear characteristics of the mooring line tensions. In recent years, scholars explore the application of neural networks to predict mooring line tensions due to the strong nonlinear fitting capacity of neural networks.
The coupled time-domain model of FPSO and soft yoke mooring system is established and sensitivity analyses are conducted to identify input parameters. Accordingly, a series of numerical analyses are carried out to extract the datasets for prediction. A multilayer perceptron (MLP) neural network model is established to predict the maximum mooring line tensions of the soft yoke mooring system in Bohai Sea in this work. The results demonstrate that the model is applicable for predicting the mooring tensions in short term sea states.
Rate of Penetration Optimization With Data Analytics Using Dynamic Trend Analysis
Authors: Ochije Uchenna Blesseth , Gravdal Jan Einar , Sahebi Hamed , Sui Dan 
Published: August 2024

Abstract
In drilling operations, optimizing the rate of penetration (ROP) remains a complex challenge due to the multifaceted interplay of dynamic drilling parameters and inherent uncertainties in subsurface formation properties. This study introduces a pioneering approach to ROP optimization through the implementation of a Moving Window Trend Analysis (MWTA) technique. The MWTA method enables real-time extraction and classification of ROP trends, providing drillers with crucial insights for enhanced decision-making and control to improve drilling efficiency and optimize drilling performance.
The MWTA method overcomes the modeling and optimization challenges by processing real-time ROP data streams, swiftly identifying fluctuations, and categorizing them into stationary, falling, or rising trends for further ROP control. This approach enables drilling engineers to promptly detect changes in ROP and make informed decisions for improved control and optimization. The complete workflow of ROP optimization with trend and dynamics analysis is presented. The simulation, validation, and testing of the efficacy of the MWTA is conducted in a high-fidelity drilling simulation environment. This simulator incorporates high-fidelity models, including multiphase flow, transient Torque & Drag, cuttings transport, drill string mechanics, and near-well formation flow and temperature interaction. Simulated real-time drilling data is streamed from the simulator, enabling the MWTA algorithm to work on the intricate relationship between ROP and drilling parameters, such as Weight on Bit (WOB), drilling mud flow rate, and Rotary Speed (RPM). The approach used in MWTA not only promises increased drilling efficiency and cost reduction but also advances safety standards, making it a compelling solution for modern drilling operations. The integration of the MWTA into real-time drilling data analytics represents a significant step toward achieving optimal ROP and enhanced decision-making capabilities in the drilling industry. This paper showcases the potential for data-driven ROP optimization, furthering the industry’s pursuit of efficient and cost-effective drilling operations.
Sandwich Pipe: Technical Viability in Subsea Gas Pipelines
Authors: Paz Claudio Moura , Gaigneux Anne-Laure , Sant’Anna do Nascimento Leonardo , Lourenço de Souza Marcelo Igor , Estefen Segen Farid 
Published: August 2024

Abstract
The exploration and advancement of subsea technology, especially in gas pipelines, has always necessitated innovative solutions. This study evaluates the potential of sandwich pipes for such applications, advocating for their technical and economical benefits over traditional single-walled pipes. To substantiate these claims, full-scale prototypes of the sandwich pipes were manufactured. These were tested at the reputable Subsea Technology Laboratory (COPPE/UFRJ). The assessment criteria were based on collapse and propagation buckling, and the installation feasibility was considered using the Reel-Lay method. This rigorous testing regimen facilitated a detailed numerical-experimental analysis. The primary goal was to fine-tune and calibrate a tool capable of accurately simulating the structural behavior of the sandwich pipe. This tool harnesses the capabilities of the finite element method within the ABAQUS software. Further, following a validation process, the study ventured into an intricate lateral buckling analysis. Here, the focus was the displacement-controlled local buckling limit state (DCC), emphasizing the pipe-soil interaction in the pre-salt region’s clay soil of the Brazilian coast. The findings were promising. The observed longitudinal strains fully complied with standards set by DNV-ST-F101 (Submarine pipeline systems) and DNV-RP-F110 (Global buckling of submarine pipelines). They remained below the critical 0.4% threshold. A comparative analysis was presented as the study culminated, emphasizing the sandwich pipe’s structural resistance to collapse and cost benefits over its single-walled counterpart.
Directional Wave Spectrum Estimation Using Ship Motion Data by Improved CGAN With Physics Guided
Authors: Li Xin , Ma Ning , Shi Qiqi , Gu Xiechong 
Published: August 2024

Abstract
The measurement of directional wave spectrum in the ocean is a crucial but challenging task. By regarding the ship as a substantial wave buoy, it is reasonable and convenient to measure the directional wave spectrum based on the ship’s motion without additional sensor cost. Given the intricacies of characterizing the relationships between wave and ship motions with precision, this study employs the Improved Conditional Generative Adversarial Net (Improved CGAN) for stable and efficient model learning to achieve the mapping of ship motions to wave characteristics within the frequency domain. A framework is introduced to enhance the model’s performance and ensure a meaningful physical interpretation by training neural network architectures with physics-based knowledge, considering factors such as energy consistency and non-negativity of wave spectra for learning physically consistent solutions. Study compares the performance of Improved CGAN without physics guided, Improved CGAN with physics guided, and direct mapping of machine learning model on the ITTC spectrum for learning and estimation. The generalization ability of the models is investigated through the zero-sample estimation of the JONSWAP-type wave spectra. Results show that by achieving consistency in energy, Improved CGAN with physics guided has good performance in terms of estimation error, stability. A single physics indicator guides the model better than two, which may prevent conflicts. On single peak spectrum similar to the ITTC wave spectrum, Improved CGAN with physics guided exhibits great generalization ability. On the spectrum with significant differences in energy shapes, it can also maintain energy consistency, enhancing stability in HS estimation and more precisely identifying mean wave direction.