bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Simulation Study on the Usefulness of the Bernstein Copula for Statistical Modeling of Metocean Variables
Authors: Vanem Erik , Lande Øystein , Fekhari Elias 
Published: August 2024

Abstract
Probabilistic modelling of relevant environmental variables are crucial for the safe design and operation of marine structures. Using metocean data, a joint model of several variables can be estimated, including their dependence structure. Often, a conditional model is assumed for this, but recently the non-parametric Bernstein copula has been suggested as an alternative tool to model such dependencies. As a non-parametric technique, it is very flexible and often provides excellent goodness-of-fit to data with different dependencies. However, non-parametric techniques are prone to over-fitting and generalizability might be challenging. Moreover, care should be taken when using such models for extrapolation. In this paper, a simple simulation study will be presented that has investigated the usefulness of the Bernstein copula in modeling joint metocean variables. First, data have been generated from a known parametric joint distribution model. Then, a joint model based on the Bernstein copula is fitted to a subset of these data. Data simulated from the Bernstein-based models are then compared to data from the initial model. A particular focus will be put on how the model captures the dependencies in the extremes.
Lessons Learned From Investigations of Torsion Failures in Cables, Umbilicals and Flexible Pipes
Authors: Mainçon Philippe , Longva Vegard , Ye Naiquan 
Published: August 2024

Abstract
Over the years, SINTEF Ocean has investigated a number of torsion-related failures in cables, umbilicals and flexible pipes. These failures have occurred during production, loadout, installation and operation. While details of each case cannot be revealed, the paper discusses the frequency of incidents, their economic impact, and some of the variety of mechanisms that cause torsion. These mechanisms can lead to complex behaviour along the route, and the notions of steady state and transients are introduced. Mechanisms of cross-section failure that have not been previously published are described.
The lessons learned from these investigations provided important inputs to the “Torsion Handbook” [1]. This document was a deliverable in the Torsion JIP (Joint Industry Project) carried out by SINTEF Ocean from 2019 to 2023 on behalf of Aker Solutions, Equinor, Hellenic Cables, NKT, Petrobras and Ørsted. Some of the approaches described in that document, to verify beforehand that an operation will not result in unacceptable torsion, are presented here.
The paper concludes, looking ahead to the work to be done to provide the industry with an engineering guideline.
Dynamic Analysis of Offshore Triceratops With Missile Launcher
Authors: Chandrasekaran Srinivasan , Unnikrishnan Ashish 
Published: August 2024

Abstract
The conventional function of an offshore platform is oil and gas exploration and production. Yet, these platforms also serve as an excellent alternative for space rocket launches, offering advantages in the form of easy environmental impact clearance. This paper conducts dynamic analyses on an offshore triceratops integrated with a missile/rocket launcher, under irregular waves. Numerical analysis is carried out for two different conditions, namely, with and without rocket launch. Average acceleration method is used to solve the governing equation in time-domain. Subsequently, power spectral densities in the active degrees of freedom are obtained from the time response analysis. It confirms the compliant nature of the structure whereby it is stiff in heave and pitch degrees of freedom while flexible in surge degree of freedom. The results provide evidence for the distinctive and innovative responsive behaviors exhibited in harsh deep ocean environments.
Toward Efficient Infrastructure Development and Project Planning for Floating Offshore Wind Energy
Authors: Sobashima Shintaro , Wada Ryota , Manuel Lance 
Published: August 2024

Abstract
The expectation of rapid growth in floating offshore wind farms (FOWFs) calls for urgent development of the associated supply chain. In this paper, we focus on the supply chain for floaters that relies on a sequence of activities including fabrication, transportation, assembly, and installation. As the intermediate stock of floaters is limited, irregular and unplanned suspension of operations that could arise due to unfavorable weather conditions would strongly influence the supply. Successful throughput in the supply chain results from the available infrastructure that defines the stock and flow capacity for each step in the project. The complexity of the interactions among the processes and the uncertainty in weather conditions pose a challenge in planning an efficient infrastructure development plan to meet the future demand of FOWFs. This study proposes a planning method that works by evaluating the performance of various configurations in such development using a stock-flow simulation model considering weather conditions. The model is validated to show good agreement with the installation process for an existing FOWF project. As a case study, we discuss infrastructure development for the Kyushu area in Japan, where results suggest several pathways to achieve desired performance.
Risk-Based Inspection and Maintenance of a Liquid Hydrogen Bunkering Facility
Authors: Campari Alessandro , Schiaroli Alice , Alvaro Antonio , Ustolin Federico , Cozzani Valerio , Paltrinieri Nicola 
Published: August 2024

Abstract
The shipping sector is responsible for approximately 4.5% of global emissions, and hydrogen was indicated as a clean and sustainable energy carrier capable of mitigating its environmental impact. The relatively high energy density of liquid hydrogen makes cryogenic storage an attractive option for maritime transport. Large-scale hydrogen bunkering facilities will be crucial to establishing an effective supply chain. Nevertheless, the chemical properties of hydrogen and its cryogenic storage conditions are reasons for concern regarding the safety of these storage plants. Preventive maintenance can reduce the likelihood of undesired events, but inspection planning is inherently challenging in the case of innovative facilities where massive amounts of hazardous substances are stored. The lack of technical data and operational experience with similar plants represents a significant bottleneck. The risk-based inspection (RBI) methodology prioritizes inspections of safety-critical components to minimize the overall plant’s risk. This highly beneficial strategy can only be adopted for hydrogen technologies with highly unrealistic assumptions. Therefore, a novel RBI approach was developed, which considers the hydrogen-specific hazards. The methodology was applied to an LH2 bunkering facility to highlight the advantages of this approach against the conventional RBI methodology.
Numerical Investigation of a High-Speed Submerged Cavitating Water Jet Based on Different Turbulence Models
Authors: Zhu Runyu , Zhang Xiaohui , Zhu Haitao , Pan Shize 
Published: August 2024

Abstract
The high-speed submerged cavitating jet can serve as an effective tool for the removal of ship fouling. Numerical simulations can provide guidance for the design of cavitating-jet-based cleaning tools. Turbulence models have a significant impact on the simulation of the unsteady cavitation. To explore effective numerical simulation methods, this study simulates a submerged cavitating jet with various turbulence models, including the SST k-ω model in the Reynolds-Averaged Navier-Stokes (RANS) method and the Stress-Blended Eddy Simulation (SBES) model, Improved Delayed Detached Eddy Simulation (IDDES) model, and IDDES model with Density Correction Method (DCM) in the hybrid RANS-LES method. The Schnerr-Sauer cavitation model is utilized to simulate the cavitation flow. The time-averaged cavity sizes and the shedding frequencies obtained by these models are compared with the data from a famous experiment to evaluate the accuracy of these methods. All hybrid RANS-LES methods successfully capture the jet core and the surrounding cavitation cloud. The SBES model captures abundant details of vortex structures. While the IDDES model tends to underestimate the dense vortex clusters around the shear layer, which can be improved by incorporating the DCM correction. Among these models, SBES is deemed the best as it predicts shedding frequency most accurately.
CO2-Responsive Foam Coupled With Nanoparticles for Enhanced Oil Recovery
Authors: Li Shaopeng , Wang Zhoujie , Li Songyan 
Published: August 2024

Abstract
CO2 foam is widely used in tertiary oil recovery and can increase oil production and reduce greenhouse gas emissions. However, separation of the oil and water phases in the fluid produced by foam flooding is often difficult. CO2-responsive surfactants can control reversible changes in the molecular structure or properties of surfactants through addition of CO2 or N2, thereby turning the foaming ability of solvents either off or on. However, traditional CO2-responsive foam has poor stability, and good results are difficult to achieve in oilfield applications.
In this work, through the use of micro-etching models, the morphological changes and flow properties of foam in porous media were observed. The effectiveness of the C12A-N20 foam in plugging and enhancing recovery in porous media was investigated using sand-packed materials. Finally, the demulsification effects of the foam flooding fluid before and after the N2 addition were compared. The experimental results showed that nanoparticles can effectively inhibit the coalescence of foam and enhance its stability. After the introduction of C12A-N20 foam into the sand-packed mixture, a significant enhancement of 14.1% in oil recovery rate was observed compared to that achieved with the injection of C12A foam, and the demulsification rate of the fluid produced by C12A-N20 foam flooding was greatly improved.
Fully Nonlinear Interaction of Water Waves and a Submerged Cylinder With Wave Breaking Detection and Suppression
Authors: Wu Qihao , Chen Yujing , Zhang Min , Shao Yanlin 
Published: August 2024

Abstract
In this paper, nonlinear interaction of regular water waves propagating over a fixed and submerged circular cylinder is numerically studied. At the structure’s lee side, the free surface profile experiences strong nonlinear deformation where the superharmonic free wave generated can be significant and are superposed on the transmitted wave. The wave profile then becomes asymmetric and skewed and may eventually reach the point of physical wave breaking. The governing equation and boundary conditions of this wave-structure interaction problem is formulated using both the fully nonlinear (FN) and the weak-scatterer (WS) theory. The corresponding boundary value problem (BVP) is numerically solved by the immersed-boundary adaptive harmonic polynomial cell (IB-AHPC) method. In this study, a pragmatic wave-breaking suppression model is incorporated into the original FN IB-AHPC solver.
Both the harmonic free wave amplitudes at the structure’s lee side and the harmonic vertical forces on the cylinder are studied. The simulated harmonic wave amplitudes are compared to other published experiment and theoretical data. In general, good agreement is achieved. The effects of the incorporated wave-breaking suppression model on the simulated results are discussed. In our study, the incorporation of the pragmatic wave-breaking suppression model successfully extends the capabilities of the original FN IB-AHPC solver.
An Experimental Study on the Diffusion Characteristics of Hydrogen by Ventilation System
Authors: Kim Jeong Hwan , Park Soung Woo , Seo Jung Kwan 
Published: August 2024

Abstract
Hydrogen gas exhibits a broader flammable limit concentration range in comparison to hydrocarbon gas, possesses lower ignition energy and ignition temperature, and manifests a heightened propagation speed of explosive flames. In the eventuality of a hydrogen gas leak, it is noteworthy that the density of hydrogen is lower than that of air, leading to its dispersion into the surrounding atmosphere within an open space. Nevertheless, within a confined environment, the hydrogen gas cloud has the potential to stagnate and accumulate. The presence of an accumulated hydrogen gas cloud elevates the risk substantially, rendering it susceptible to ignition or explosion, even in the presence of a minor ignition source. The purpose of this study is to experimentally investigate diffusion characteristics in response to diverse ventilation methods in the event of hydrogen leaks within the Fuel Gas Supply System (FGSS) room. A FGSS room, representative of the dimensions of an operational hydrogen fuel propulsion ship, was fabricated for the purpose of this investigation. Ventilation capacity was systematically compared and analyzed, taking into consideration variables such as ceiling type, ventilation method, and the length of the ventilation duct. Moreover, the FLACS program was employed for numerical analysis, and a modeling technique for simulating hydrogen leakage diffusion in enclosed spaces was developed through a comprehensive comparison and verification with the experimental findings. The amalgamation of experimental results and the refined numerical approach holds potential utility in informing adjustments to existing International Maritime Organization (IMO) guidelines and the International Code of Safety for Ships using Gases or other Low-flashpoint Fuels (IGF Code).
Dynamic Response Control of 2-D Jacket Structure Using Semi-Active Tuned Liquid Column Damper (TLCD)
Authors: Paul Bapon , Kumar Deepak 
Published: August 2024

Abstract
The jacket structure is a fixed offshore structure. Its natural frequency of vibration is higher than the peak ocean wave frequency. Generally, the response of the jacket structure platform is significantly small in comparison to other floating offshore structures. But, the small response is good enough to generate significant stress at the joint level of jacket members. This is due to the rigid connection between the members at the joint level. In literature also, it’s well-studied that the joint of the jacket structure is vulnerable to stress developed and shows fatigue damage. Further, a reduction in the response of jacket structure using conventional design procedures may have a huge financial burden. So, dynamic response control of such a structure to reduce the effect of fatigue damage at the joint of members is the most economical and practical approach. In this paper, a tuned liquid column damper (TLCD) is used as a passive control device to control the response of the jacket structure. The control in response is achieved by tuning the TLCD at the natural frequency of the Jacket structure. This gives control only at the natural frequency of the structure, but the response at excitation frequency remains unchanged. This way, the total control achieved is not good enough. Further, TLCD is converted to semi-active TLCD by changing the pressure at the column. The fuzzy control algorithm is used to guide the pressure changes in the TLCD column so that optimum control at the natural frequency of the jacket and excitation frequency can be achieved. Further, the robustness of Semi-active TLCD is also shown based on a change in the nature of excitation.
A Tool for Reliability-Based Inspection Planning of Mooring Chains
Authors: Almeida de Rezende Filipe , Videiro Paulo Mauricio , Volnei Sudati Sagrilo Luis , de Oliveira Mauro Costa , dos Santos Gabriel Yudy Matsunaga 
Published: August 2024

Abstract
The safety of offshore floating units highly depends on the platform’s station keeping capability, which is provided by its mooring system. Mooring chain fatigue failures have recently aroused the interest of the technical community in developing new design and monitoring methodologies focused on considering the effects of corrosion degradation in time. The fatigue limit state and the corrosion allowance of mooring chains are safety requirements that need to be verified continuously through mandatory regular inspections. The present work proposes a new efficient reliability-based method for planning future inspections of mooring chains, which combines recently developed fatigue assessment and corrosion methodologies and takes into account the observations of the previous inspections. The risk-based assessment of the mooring system is continuously updated with new inspection data, being a suitable tool for monitoring the current reliability level of the structure. The method is incorporated into a computational tool that monitors the system reliability and drafts future inspection dates based on a sound safety criterion. Additionally, this work presents a case study as an application of the proposed inspection planning method. The results show that the proposed method is able to optimize the number of inspections in all the analyzed scenarios, and it may be used as a relevant tool to help designers and operators in avoiding mooring chain failures.
Underpinning the Value of Buoyant Urbanism: Returning Torrens to the Seas
Authors: Cradduck Lucy M. , Wang Brydon T. , Weinert Kim D. 
Published: August 2024

Abstract
The rise of buoyant urbanism, in the form of floating developments, amphibious architecture, and floating cities; has introduced a new dimension to the traditional understanding of what is ‘real estate’. These innovative forms of development continue to gain prominence and need to be promoted and protected. To engage with the threat of climate change, and the growing incursion of water in our urban spaces, there is a need to ensure appropriate recognition of related property rights and interests. Concurrently, there is a need for valuation of those rights and interests to be linked to a recognised land tenure system to support investment within the Blue Economy. Therefore, our starting point is to develop an international system of recognising, protecting, and articulating the underlying tenure. This paper aims to extend previous research concerning how floating structures are a unique species of property capable of having tenure. However, there are tensions in property law (across common law and civil jurisdictions) concerning these structures, which manifest a rigid view of what is real property. By means of a case study, the solution proposed posits floating structures as a new class of real property within international waters (the global commons). Thereby, if the law understands floating structures as a resource capable of registration akin to real property, the structure itself will be afforded proprietary interests. As the Torrens system of land titling (title by registration) was developed from concepts underlying the registration of vessels, it is now time to return Torrens to the Seas. In doing so, the proposed buoyant urban registration system will be conceived to achieve sustainable use of marine resources under the Blue Economy.
Field Study of Biofouling on the Surface of Synthetic Fiber Ropes in Japanese Coastal Waters and its Influence on the Engineering Characteristics of Hybrid Moorings
Authors: Haneda Ken , Chujo Toshiki , Kojima Ryuji 
Published: August 2024

Abstract
A hybrid mooring system with steel chains and synthetic fiber ropes for offshore floating wind turbines is attractive for several reasons, including lower material costs. However, the degradation of synthetic fiber ropes over long-term use has not been fully verified. In this study, the authors focus on the biofouling on the rope. The impact of biofouling on the rope surface includes (1) increasing the line weight of the rope and changing its initial catenary shape, (2) increasing the total diameter of the rope section and changing its dynamic behavior. The authors investigated the biofouling of ropes through a combination of field experiments and numerical simulations to assess its impact on the static and dynamic behavior of mooring lines. Two-year field experiments were conducted at three coastal stations in Japan to clarify the biofouling using different synthetic fiber ropes as specimens. The specification of the specimen was 56 mm in diameter and 1 m in length, made of nylon or polyester. The experiments recorded 83 mm as the maximum biofouling thickness and 100 N/m2 (17.7 N/m) as the weight of the biofouling. Based on the result, numerical simulations were also conducted to clarify the impact of the biofouling on the rope. The results showed that biofouling on the synthetic fiber ropes that make up the catenary mooring had virtually a little effect on the initial catenary shape or tension fluctuations.
A Methodology to Assess Craze Initiation in PVDF Pressure Liners
Authors: Granum Henrik , Holmen Jens Kristian , Bonanni Michele , Al-Zubaidy Majeed , Kirton Peter , Roberts Andrew , Nygård Per , Holmström Jens Petter Henrik , Østby Erling , Hund Jonas , Perillo Giovanni , Johnsen Joakim 
Published: August 2024

Abstract
Crazing has been observed in flexible pipe PVDF pressure sheaths in operation. Whilst no loss of containment has been identified, Baker Hughes and Equinor have collaborated with Enodo and NTNU to investigate the root cause of the mechanism and develop a predictive framework. We developed a methodology involving a combination of finite element (FE) simulations and high-pressure tests to establish a craze capacity curve for the material. A custom polymer material model was implemented in Abaqus and calibrated using various tension and compression tests covering a wide range of stress triaxiality ratios and strain rates. Crazes were generated in circular discs using a custom-built rig for high-pressure testing. Water was used to pressurize one side of the discs up to 2000 bar. The stress and strain state in the discs were varied by changing the disc thickness, disc radius, backing plate geometry, and the applied pressure. We simulated the high-pressure tests and compared the deformed shape of the discs between simulations and tests. Numerous simulations and corresponding tests formed the basis for a material capacity curve predicting the onset of craze formation. The material capacity curve is a function of the applied fluid pressure and the principal strain difference.