bluuebunny/crossref_metadata_2025_split huggingface dataset:
Predicting the As-Laid Embedment of Surface-Laid Pipelines and Cables in Sand Wave Regions
Authors: Hou Zhechen , Bransby Fraser , Watson Phil , White David , Ballard Jean-Christophe , Delvosal Pierre , Denis Raphael , Low Han Eng 
Published: September 2023

Abstract
Predicting the as-laid embedment of surface-laid pipelines and cables is important for estimating their in-service response. To date, design approaches have only considered flat seabed conditions. The as-laid embedment is estimated using vertical ‘lay down’ seabed springs that are calculated allowing for the pipeline geometry and weight as well as its interaction with the seabed during the dynamic lay process. This paper addresses the important and different case where pipelines and cables are laid on a seabed with bedform features (e.g. sand waves, mega ripples or ripples). The measured as-laid embedment for a pipeline installed within a region of sand waves on the North West Shelf of Australia is examined and compared with numerical simulations of the lay process. Good agreement with the field embedment is obtained for both flat and sand wave zones. However, this is achieved using soil springs that are around 10 times softer than prescribed by current recommended practice. This is attributed to the neglect of dynamic lay effects in design guidance for sands and the high compressibility of carbonate soils. The field data and the simulations both show that the pipe embedment varies throughout each sand wave. The maximum embedment near the sand wave peak is greater by a factor of up to 5 compared to the minimum embedment found near the sand wave trough. The embedment profile is phase-shifted from the sand wave profile by 10–20% of the sand wave length.
A Coupled Fluid-Structure Model for Estimation of Hydraulic Forces on the Tool-Joints
Authors: Volpi Lucas P. , Cayeux Eric , Wiggo Time Rune 
Published: September 2023

Abstract
Most models employed for fluid forces in drill-string dynamics are of reduced order. The simplified nature of these models often fails to describe complex behaviour of the fluid force, in particular when the drill-string movement is non-trivial or even when non-Newtonian behaviour is predominant. In this work, the fluid forces are estimated by modelling the dynamic of the drilling fluid for both Newtonian and non-Newtonian fluids, and compared with reduced order models. To achieve it, the lattice Boltzmann method is implemented to solve the fluid model, while prescribed movements are set for the tool-joint. With the obtained fields, the forces are calculated and compared with recurrent models. Finally, it is observed that some models are capable of describing the interaction as long as the dynamic of the tool-joint is simple. In the presence of other trajectories — e.g.: bouncing and chaotic — the models fail to describe the details of the dynamic.
A Methodology for Tuning of Computational Vessel Models Utilizing Wave Measurements From X-Band Marine Radar and Wave Buoy
Authors: Radhakrishnan Gowtham , Leira Bernt J. , Gao Zhen , Sævik Svein , Kaasen Karl E. , Christakos Konstantinos , Dirdal Johann A. 
Published: September 2023

Abstract
Accurate estimation of the wave field and subsequent vessel response prediction are vital for making crucial judgments on the safe and timely execution of marine operations. Decision support systems based on the Response-Based Decision-Making (RBDM) methodology are still in the early stages due to the challenges in addressing the uncertainties in the environmental conditions and vessel computational models. Therefore, this study offers a model tuning technique that utilizes the waves measured from an onboard X-band wave radar, wave buoy, and simultaneously measured vessel motions using an Inertial Measurement Unit (IMU), for applications in RBDM. For this purpose, full-scale wave and vessel response measurements were conducted using the NTNU research vessel Gunnerus on the west coast of Norway. The on-site directional wave spectra are obtained by processing the backscattered radar images using existing inversion schemes. Furthermore, the directional wave spectra are also derived from the nearby wave buoy measurements using the Maximum Entropy Method (MEM). The influential system variables in the vessel model that induce maximum variation to the response Quantities of Interest (QoIs) are quantitatively identified using probabilistic sensitivity indices. Out of the 31 system variables, only 14 were considered influential and subsequently tuned by minimizing the error between the measured and simulated response spectra. Heave, roll, and pitch modes were tuned and results exhibit superior agreement with the measured response spectra.
Long-Term Corrosion of Parked and Abandoned Offshore Steel Pipelines
Authors: Melchers Robert E. 
Published: September 2023

Abstract
Internal corrosion of steel pipelines before use, or temporarily taken out of use, and ‘parked’ on the seafloor for some time (months), suspended from operation or ‘abandoned’ for extensive period of time continues to be an issue for offshore operators and regulators. This is irrespective of whether the pipes are gas or oil production or water injection pipelines. Severe pitting corrosion, sometimes observed at the 6 o’clock position, conventionally often is assumed the result of microbiologically influenced corrosion (MIC), particularly if coupled with high bacterial concentrations in the rusts. Dosing with biocides is not always effective and increasingly is considered environmentally undesirable. This paper provides a brief overview of the fundamental requirements for long-term corrosion under low oxygen and essentially stagnant environmental conditions. It shows that any severe internal corrosion at the 6 o’clock position has similarities to that sometimes observed for water injection pipelines and likely the result of under-deposit corrosion resulting from the deposition of rusts and other debris. MIC may contribute providing there is availability of necessary nutrients. Generally similar issues apply for the external and interior corrosion of abandoned pipelines. Avenues for further research and development are outlined, including for pipelines proposed to be abandoned.
Rapid Residual Strength Assessment of Degraded Mooring Chains Using an FEA Based Response Surface Modelling Tool
Authors: Gunn David , Dimopoulos Simon , Carra Chris 
Published: September 2023

Abstract
Design of moorings with chain sections typically assume a level of uniform through-life corrosion and wear. The associated reduction in strength is, in simplistic terms, estimated by assuming a smaller as-new chain diameter.
Where inspections show chain links to have localised material loss the resultant reduction in strength is harder to account for as it is dependent on the volume, shape and location of the loss. Discard criteria found in design standards are necessarily conservative as they must encompass the most damaging combinations of size, shape, and location of material loss. As a result, operators have turned to Finite Element Analysis (FEA) to directly assess the effect of localised chain material loss. Whilst this approach has been shown to be effective it incurs significant computational cost and is time consuming and expensive when compared to the application of these simple discard criteria.
The Corroded Chain Analysis and Structural Evaluation (CCASE) tool has been developed to leverage the benefits of FEA while reducing significantly the time and cost associated with a chain anomaly assessment, providing a rapid prediction of the degraded chain’s residual strength within minutes.
CCASE utilises the results of FEA conducted previously for the Chain FEARS JIP as well as newly performed FEA for pitting, seabed, hawsepipe, and interlink wear anomalies to generate a Response Surface Model (RSM) of Break Load Prediction. The geometry of the degraded chain links is input into CCASE via a point cloud file typically obtainable by surface or subsea photogrammetry scanning methods. These chains are then characterised by the tool, relative to an idealised chain link, at a number of cross sections around the geometry. These characteristic parameters, when used with the Response Surface Model (RSM), predict the break load of the degraded chain link.
The CCASE tool was able to predict the break load of test degradation geometries, independent of those used to develop the RSM, to within approximately 5% of the break load predicted by the FEA approach for the cases tested and within a similar margin for two cases involving real-world degraded chain pulled to destruction on a test rig.
CCASE can thus be used to perform rapid, cost effective engineering assessments of chain anomalies in place of traditional conservative discard criteria. This gives an operator a clearer decision path to continue to monitor chain anomalies or commit to expensive replacement works.
The Study of the Wave Attenuation Performance of Triple Plates Interacting With a Solitary Wave
Authors: Wen Chang-Qing , Wu Jing-Ping 
Published: September 2023

Abstract
In order to explore measures to reduce tsunami wave height, this paper uses solitary waves instead of tsunamis, numerically simulates the interaction between triple rigid flat plate model and solitary waves, and analyzes the effects of the dipped depth, plate spacing and tilt angle on the transmission coefficient. The triple rigid plates are the same scale and remain unchanged. The relationship between plate length L and water depth h is L/h = 0.4; the vertical distance d from the lower end to the water surface is used to change the position of the plate in the water. Triple plates is in the equal space S arrangement. Based on the Fluent software platform, a two-dimensional numerical wave flume is constructed, and the piston-type solitary wave generation method based on Goring is used to simulate the physical solitary wave. Firstly, a solitary wave is numerically constructed at different truncation velocities R, and compared with the solitary wave height of the analytical solution and the experimental results, the numerical simulation parameters such as the truncation velocity R with sufficient accuracy are determined. Then, under the same water depth h and solitary wave height H, the propagation of solitary waves in triple plates under 9 kinds of relative dipped depth d/h, 16 kinds of relative spacings S/λ and 15 kinds of tilt angles is numerically simulated, the transmission coefficient Ct of the model is calculated, and the effects of the relative dipped depth, relative spacings and tilt angles of the plates on the transmission coefficient Ct are analyzed. The results show that the transmission coefficient decreases first and then increases with the increase of the relative dipped depth d/h, and there is an optimal relative dipped depth d/h. The transmission coefficient decreases monotonically with the increase of the relative spacings S/λ, and tends to be flat. When relative dipped depth d/h = 0.13 and the relative spacings S/λ = 6.69%, the transmission coefficient is the smallest at the tilt angle of 75°.
Tribological Performance of Nylon-6/Oyster Shell Composites
Authors: Ambika Harikumar Akshay Krishna , Heitzmann Michael Tobias , Basnayake Asanka , Khakbaz Hadis , Martin Darren 
Published: September 2023

Abstract
Polyamide-6 (PA6), an engineering thermoplastic polymer widely used in tribological and structural application due to its low-cost, manufacturing ease and better performance. PA6 exhibits high strength, high modulus, abrasion resistance and can be manufactured via injection moulding technique. Wear and mechanical performance of PA6 reinforced with oyster shell powder at different filler contents were investigated in this paper. Raw oyster shell was sourced from the local supplier and series of steps have been performed to manufacture the composite material as shown in Figure 1.
Tensile and wear tests were carried out on the injection moulded composite specimens. Addition of oyster shell has positivity influenced the tensile strength and modulus of PA6 polymer material and increased with increasing filler content. Strain at break has significantly dropped by the addition of oyster shell filler and decreased with increasing filler content. Composite materials have shown a higher wear rate compared to the pure polymer.
Suction Caisson Anchor and Dynamically Installed Fish Anchor in Calcareous Silt
Authors: Hossain Muhammad Shazzad , Mohiuddin Mohammad Arif , Chang Kuntan , Koh Kaixiang , Kim Youngho 
Published: September 2023

Abstract
Suction caisson anchors are proven reliable anchoring solutions for tethering floating facilities in shallow to deep water. Dynamically installed anchors have been identified as the most cost-effective option for particularly deep water developments. Recently, the dynamically installed fish anchor has been introduced, adopting a geometry taken from nature. Physics for installing these two anchors are different. However, owing to the counterbalancing effects of strain rate dependency and strain softening the operative undrained shear strength around these two anchors may be similar. After the completion of installation, for suction caisson anchors, the skirt is embedded in the seabed with a soil plug inside and the lid sits on or slightly above the mudline, and for dynamically installed anchors, the whole body is mostly fully embedded into the ground. Furthermore, under operational loadings, the fish anchor is found to dive (penetrate deeper) in the seabed deposit. These different embedment conditions and potential diving for the fish anchor cause differences in the behaviour and mobilised capacity under operational monotonic and cyclic loadings in calcareous silt.
Proposal for Motion Stabilized Platform of Doppler Lidar for Offshore Wind Observation and its Validation
Authors: Yamamoto Yusuke , Kinugasa Mizuki , Morota Hiroki , Katayama Toru 
Published: September 2023

Abstract
In this study, a rigid body swing with motion control as a motion stabilized platform of Doppler Lidar to place on floating platform is investigated. First, a counter-weight type motion stabilized platform is proposed, and its effectiveness of motion reduction on a spar-buoy type floating platform with tension-mooring is confirmed by numerical simulations and model tests. Furthermore, skyhook damper and spring controls are applied to the motion stabilized platform to optimize its motion, and it is confirmed by numerical simulations that its effectiveness of motion reduction is significantly increase. Finally, the motion stabilized platform is set on a discus-type floating platform whose motion is much larger and complicated than a spar-buoy type floating platform and its effectiveness is also confirmed by numerical simulations.
Application of Drilling Fluid Circulation Technology to Lifting System for Deep-Sea Mineral Resources
Authors: Kitago Ryuta , Naganawa Shigemi , Bjarkason Elvar Karl 
Published: September 2023

Abstract
Various types of deep-sea mineral resources such as mud containing rare earth elements, manganese nodules, cobalt-rich crusts, and methane hydrate are found on deep-water seabeds around the world. Lifting systems for mining these resources using a gas lift approach or submersible pumps have been studied by many researchers. As an alternative to these lifting systems, this study proposes a rare earth mud lifting system using a hydraulic jet pump, like those used for artificial lifting in oil wells. The objective of this study is to investigate the design of this lifting system to maximize the mud suction rate of the hydraulic jet pump by numerical simulation. The hydraulic jet pump simulations involved two-phase flow of seawater as the working fluid and rare earth mud slurry as the production fluid. The simulation results showed that all the considered hydraulic jet pump designs could suck in highly viscous rare earth mud slurry at an ocean depth of about 7,000 m. A design with three sets of suction lines and diffusers gave the best performance and could transport a rare earth mud slurry at commercially viable combinations of flow rates and mud concentrations. At a suction line diameter of 1″, the produced mud rate exceeded the commercial reference standard, with mud recovery rates of 10,500 ton/day and 15,800 ton/day when the volumetric mud concentration of the slurry entering the pump was 20% and 40%, respectively.
A Study on the Fracture Toughness Evaluation Considering Material Tensile Characteristic for Cryogenic Steel
Authors: Kim Ji Hoon , Jeong Young Cheon , Cho Dong Pil , Kim Myung Hyun 
Published: September 2023

Abstract
ISO 12135, a representative standard for the evaluation of fracture toughness, was revised in 2021. In the previous standard published in 2016, only yield strength was reflected for material property in fracture toughness calculation. In the revised standard, however, yield to tensile strength ratio is additionally reflected in consideration of strain hardening effect of the material. The current fracture toughness calculation formula evaluates fracture toughness reasonably considering the tensile characteristic. However, in some cases of cryogenic steels, fracture toughness is evaluated very conservatively than the previous procedure in 2016. In the case of STS 304L, there is no ductile-brittle transition phenomenon and it has excellent ductility and strength in cryogenic temperature. However, due to the secondary hardening phenomenon, yield to tensile strength ratio is relatively low, and as a result, fracture toughness is evaluated very low. The target of this study is to resolve the undervaluation of fracture toughness of cryogenic steel in the revised ISO 12135. For this purpose, the elastic and the plastic parameters in CTOD equation in ISO 12135 is examined. The crack tip profile is derived by a series of finite element analysis and crack tip opening displacement is calculated for the derivation of new parametric equations for cryogenic materials. The calculated crack tip opening displacement is validated by experimental results.
Demonstrating Electrically Heat-Traced Flowline (EHTF®) Performance – As-Built Engineering Versus Field Data, the Perfect Match
Authors: Mencarelli Guy , Minier Yves , Silcock Donald , Pradeilles Camille , Michel Xavier , Gibson David 
Published: September 2023

Abstract
As part of the Aker BP Skarv field development, the Ærfugl phase 2 project is a 13km tie-back requiring an electrically heated flowline to provide a reliable and cost-effective hydrate management solution.
This paper will present at first the reverse engineering work done on the thermal and electrical performances of this first generation of EHTF® system based on field data. In production since November 2021, operational feedbacks on the highly insulated Pipe-in-Pipe associated to the distributed temperature monitoring system have been used to confirm the passive thermal performance of the system as targeted and predicted by design. In addition, data gathered during the performance tests performed in May 2022 as part of a planned production shutdown have been processed; the results clearly demonstrating the perfect match between predicted system performances using Subsea7 design & engineering models and recorded topside electrical parameters and subsea heating performances.
Then, based on those robust engineering models, typical EHTF® performances will be presented to provide more insights on achievable EHTF® system capabilities.
This is indeed a key achievement demonstrating the maturity of the technology and providing to operators an increased level of confidence in the EHTF® technology and in Subsea7’s design, fabrication, and installation abilities to deliver EHTF® solutions on future field developments as specified and planned.
To conclude, the paper will present the next generation of EHTF®, achieving longer tie-back distances while capitalizing on the first-generation knowledge and technology.
Investigation of Simulation and Tank Tests for Motion Behavior of Semi-Submersible Platform DeltaFloat With a 10 MW Wind Turbine
Authors: Huang Zheng-Zhang , Chou Shean-Kwang , Chung Cheng-Hsien , Wu Hua-Tung , Hsu Hao-Teng , Wu Yan-Wen , Chiu Forng-Chen 
Published: September 2023

Abstract
The government of Taiwan is promoting developments within offshore and coastal structures, which includes developments within the floating offshore wind turbine (FOWT) sector. The aim of the development plan is to lower the FOWT lifetime cost of energy so they eventually are competitive with bottom-fixed wind turbines. Model test of design concepts and verification of numerical software are important aspects of such developments. The present study investigates the existing design concept using both numerical software and experimental tank tests. By examining the potential site condition, where Hsinchu waters are specified as well as manufacturing capabilities and infrastructure in Taiwan, the semi-submersible platform DeltaFloat used for DTU 10 MW wind turbine is proposed.
In order to compare the design of a floating wind turbine accurately, a water tank model test is planned to verify the motion behavior of the design. The motion response and free decay of the floating platform structure are discussed. By establishing a floating platform model and instruments, free motion decay and regular wave tests were conducted, and then the motion behavior of the floating platform and the tension of the mooring chain were measured. The test results were compared with the simulated ones, which show good approximation.
Deep Learning Based Prediction of Hydrodynamic Forces on Offshore Platforms
Authors: Miyanawala Tharindu Pradeeptha , Li Yulong , Law Yun Zhi , Santo Harrif 
Published: September 2023

Abstract
Irregular ocean waves cause fluctuating non-linear hydrodynamic forces on the body, which is an importance factor to account for in offshore and marine applications. While physical experimental and computational techniques provide valuable physics insight, they are generally time-consuming and expensive for design space exploration. We present an efficient Long Short Time Memory (LSTM) based deep-learning technique to predict unsteady hydrodynamic forces on slender bodies, where drag forces are more dominant than inertia forces. A leaky non-linear rectification is employed to approximate the mapping between surface elevation time series and hydrodynamic (drag) force time series. The deep neural network is fed with irregular waves based on JONSWAP spectrum as the input and the target data generated by the full-order Navier-Stokes computations using a generic offshore jack-up platform. The LSTM is trained using a stochastic gradient descent method to predict time series of the hydrodynamic forces on the jack-up and the results are compared with the full-order computations. Within the error threshold, the predictions based on our deep convolutional network have a speed-up of nearly 2 orders of magnitude compared to the full-order results and consume an insignificant fraction of computational resources. Overall, the proposed LSTM-based approximation procedure has the potential to be used for parametric design and digital twinning of jack-up platforms.