bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modeling and Control Design for Ship Hybrid Propulsion Systems
Authors: Gao Fan , Brodtkorb Astrid H. , Zadeh Mehdi , Mo Sigrid Marie 
Published: August 2024

Abstract
This paper presents the modeling and controller design of hybrid propulsion systems with shaft generator. The proposed modeling framework is simulated and validated with a case study of a line-fishing ship, M/S Geir. The studied hybrid propulsion system consists of a main diesel engine, a shaft system with gearbox, and a controllable-pitch propeller (CPP), while the electric system incorporates two auxiliary gensets, a shaft generator, a bidirectional drive, and a battery set. Efficiency models have been developed and analyzed for each individual component in the proposed framework. The proposed methodology of integrating simplified dynamic models with efficiency models enables a comprehensive evaluation of efficiency and dynamic analysis for large hybrid ship power and propulsion systems. The presented analysis provides insights into the coordinated functioning of the various components, offering a holistic perspective on the hybrid system’s efficiency and performance within the specific operational context of the use case vessel M/S Geir.
Lateral Buckling Control With Residual Curvature Method for Ultra Deep Water Flowlines
Authors: Jebali Adel , Solano Rafael F. , Caine Julien , Romero Antonio P. G. , Dos Santos Thiago L. A. , Hansen Alexandre S. , Amarante Jonylson 
Published: August 2024

Abstract
The lateral buckling design process for deep and ultra deep water fields has matured in recent years, particularly with steel sleepers and/or distributed buoyancies as the main triggering concepts (buckling initiators). However, depending on field conditions and geographical location, complex engineering, manufacturing, or installation may be encountered. Furthermore, the solution may not be cost-effective, especially for projects requiring a large number of triggers.
The residual curvature method (RCM), which offers an economical and practical solution with low environmental impact, has been used frequently for shallow water projects and rarely proposed for deep and ultra deep water. This is essentially due to the challenges in terms of landing orientation of the RCM on very soft soils associated with deep water and the resulting in-place reliability question.
This paper will present how the Residual Curvature Method can be used as a reliable buckling control measure for ultra deep water flowlines operating under high internal pressure and high temperature (HPHT) conditions. The case study is the Mero 2 project offshore Brazil.
The Mero 2 ultra deep water project includes rigid mechanically lined pipeline (MLP) systems which operate under HPHT for oil production and water alternating gas injection. The pipelines are exposed (unburied) with fully restrained anchoring systems at both ends using pin-piles. They will withstand high operating conditions, including permanent and transient flow regimes with several shutdown/restart cycles predicted during the design life. This induces large compressive axial forces in the pipeline without expansion absorption at either end (no sliding, i.e. fixed-fixed) and requires, therefore, buckle initiators such as RCM to control the lateral buckling behavior.
The solutions and measures proposed to ensure acceptable RCM lateral offset, under as-laid conditions, will be presented. The interaction between the residual curvature (RC) and soil, as well as the competition with on-bottom rogue buckles, will be shown. The reliability and robustness of the proposed lateral buckling solution for Mero 2 pipelines will be discussed. In addition, the advantages of the RCM and its limitations will be reviewed.
The Front Runner of Roll Waves in Mudflow
Authors: Yu Boyuan , Chu Vincent H. 
Published: August 2024

Abstract
Mudflow is destructive because of its intrinsic tendency to become unstable, leading to roll waves that can impact structures with great force. We examined the rheological properties of landslide muds, conducted direct numerical simulations of the roll waves in the mudflow, and compared the results obtained from a shallow mudflow model. Simulations are performed to study (i) the temporal growth of periodic disturbances of different wavelengths and Froude numbers and (ii) the spatial development of the wave packet produced by a local disturbance. Most existing studies of roll waves are concerned with periodic roll waves derived from shallow mudflow models, assuming hydrostatic pressure variation and a constant velocity profile over the depth. However, this paper focuses on the spatial development of front-runners. The solution to the hyperbolic equations, derived from the shallow-mudflow approximation, is shock waves of depth and velocity discontinuities at the wavefronts. On the other hand, the direct numerical simulations of the laminar mudflow can show a more realistic mudflow instability that includes wave breaking and entrapment of air during the beaking. Nevertheless, despite the discontinuity, the shallow-mudflow model is still a reasonable approximation in the region away from waves breaking when the wavelength of the front runner becomes sufficiently large.
Optimization of Offshore FPV Modules in Early Design Phase
Authors: Jin Jingzhe , Zhang Liqing , Lin Zhiliang , Kong Jiehong , Gao Zhen 
Published: August 2024

Abstract
Offshore Floating Photovoltaic (FPV) systems are gaining attention due to the high Technology Readiness Levels (TRL) of PV panels and offshore structures. Numerous offshore FPV design proposals exist, but none have yet met industrial standards. The designs fall into two main categories: membrane type supported by a floating collar/air cushion and modular structure type comprising interconnected FPV modules. This paper uses semi-analytical methods to optimize the modular structure type design, considering fabrication cost, module stability, and hydrodynamic response in waves.
Navigating the Future: Strategic Management of a Mobile Aquaculture System With Receding-Horizon Control
Authors: Pillai Ajit C. , Ashton Ian G. C. , Johanning Lars , Cook Denham G. , Vennell Ross , Black Suzanne E. 
Published: August 2024

Abstract
The New Zealand-based Whakapōhewa ki ahumoana Reimagining Aquaculture project (funded by the Ministry for Business, Innovation and Employment Endeavour Fund) lead by Plant & Food Research, is designing a mobile aquaculture system for finfish, towed by an autonomous vessel, powered by renewable energy sources.
This work presents the vessel management strategy for this mobile aquaculture solution, inspired by receding-horizon control, which uses available weather forecasts to minimize the energy consumption by the autonomous vessel while maintaining an optimal flow speed through the fish enclosure such that the optimal biological conditions (e.g. swim speed) for the fish can be maintained. The simulations performed for a generalized salmonid fish species cultured in Tasman Bay, New Zealand show that the food storage capacity of the autonomous vessel is consistently a limiting factor at low swim speeds (≤ 0.4 m s−1), while energy capacity limits at higher swim speeds. The simulations highlight how such a strategy allows the system to successfully shelter from storms and by virtue of going further from its “safe haven” can maintain optimal conditions for the fish through the enclosure. We anticipate this work to be a starting point for more sophisticated management strategies considering engineering criteria, species specific requirements, and environmental parameters such as temperature and water quality that impact fish welfare explicitly.
Simplified Three-Dimensional Finite Element Models of a Flexible Pipe Interlocked Carcass Under Bending
Authors: Geremias Toni Fernando , Provasi Rodrigo , de Arruda Martins Clóvis 
Published: August 2024

Abstract
A flexible pipe interlocked carcass is characterized by having both high flexibility and radial stiffness, being, therefore, a layer of relevant structural function. When designing a carcass, these two properties must be met at the same time, which is only possible thanks to its helical and interlocked geometry. On the other hand, the geometric complexity makes its modeling process equally complex, whether numerical or analytical. In this context, over the last years, the authors published some papers with the objective of better understanding the mechanical behavior of the carcass under tension and bending loads, as it is important for the development of more efficient modeling techniques. Regarding bending, two fully three-dimensional finite element models of the interlocked carcass were recently presented, which considered the exact helical shape of the carcass and all contacts involved in the interlocking. Despite being very complete, these models were quite computationally expensive models. To simplify the carcass modeling process, the ring hypothesis is commonly adopted, which consists of disregarding its lay angle. This approach has already been widely used and studied for collapse problems, but, to the authors’ knowledge, its impact has not yet been evaluated for the bending case. Therefore, the present work proposes a series of simplified finite element models of the interlocked carcass under bending loads and that are computationally efficient, in addition to a detailed evaluation of the impacts of all adopted simplifications, always having as paradigm for comparison the costly, most complete, fully helical interlocked versions.
Evaluation of the Inner Liner in Unbounded Flexible Pipelines in the Sealing System of End-Fitting
Authors: Saneian Mohsen , Bai Yong 
Published: August 2024

Abstract
Unbonded flexible pipelines are widely used in the offshore oil and gas industry due to their numerous structural configurations and their adaptability to different environmental requirements. However, designing the end-fitting for connecting these pipes to the floating structure is one of the most challenging tasks. This connector has two main functions, ensuring sealing of the pipe fluid and transferring the loads from the pipe to the connecting system unit. The flexible pipes consist of many layers including carcass, inner liner, pressure armour, tensile armour, and outer sheath. The carcass prevents the collapse of the pipe against high hydrostatic pressure, and the inner liner plays the most significant part in the sealing system of the end-fitting. The current study assesses this role. The sealing method is based on dividing the termination of risers into two devices; barrier seal which is the mechanical restraint on the polymer barrier, and the seal system that is applied to seal the fluid of the riser. Therefore, two leak paths are observed; between the barrier seal and the polymer barrier, as well as, between the barrier seal and the body. Consequently, to improve the metal seal ring under high pressure, the compression on the polymer barrier must be enough. Besides, the contact pressure at the metal-to-the-metal interface has to be adequate.
A Flexible Support System for Large Wind Turbines
Authors: Zhao Wangwen 
Published: August 2024

Abstract
As offshore wind turbines scale up for LCOE reduction, foundation costs could spiral out of control. We propose a revolutionary flexible support system that slashes loads on the tower by up to 90%.
This design prioritizes load reduction over resistance with the following key features:
• Aerodynamic Shaped Tower Section: Minimizes wind forces while maximizing structural efficiency.
• Self-Alignment with Wind: Eliminates complex active yaw systems, boosting energy capture and simplifying design.
• Passive Yaw Control: Harnesses wind to guide the rotor, lowering maintenance and enhancing reliability.
These features lead to large LCOE reduction by reducing CAPEX from lighter and simpler tower and foundation, reducing OPEX via simplified maintenance, and increased energy production. This disruptive approach unlocks wider wind adoption including floating or fixed, onshore and repurposement, accelerating the transition to a sustainable future.
On the Applicability of DNN-Based Models Trained Under the Fixed Spar Condition to Control Force Estimation of a TLP Moored PA-WEC
Authors: Kawagishi Tatsuki , Murai Motohiko , Han Jialin 
Published: August 2024

Abstract
One of the ocean renewable energy sources is wave energy. This study focuses on a floating point-absorber wave energy converter (PA-WEC). A PA-WEC is composed of a float and a spar, with the float moving in heave relative to the spar. The relative motion generates electricity. However, the generated electric energy may decrease sharply when the heave motions of the float and the spar are in phase. To address this issue, one of the approaches is to minimize the heave motion of the spar by mooring it with a tension leg platform (TLP) that consists of a footing and tendons (mooring lines).
In real sea, the appropriate control force cannot be identified instantaneously. This is because the periodic components of the irregular waves are “unknown”. The authors have investigated that the appropriate control force could be estimated instantaneously using deep neural network (DNN)-based trained models by considering only the heave motion of the float assuming the spar remains fixed in space. However, in fact, the spar is moored. Even if a TLP moored PA-WEC, the surge/sway motions may have an influence on the heave motion of the float relative to the spar, and consequently affect the power generation performance of the PA-WEC.
The purpose of this study is to reveal whether the DNN-based models trained under the condition where the spar remains fixed can be applied to a TLP moored PA-WEC. These trained models can be built without a prior knowledge of the mooring of a PA-WEC. Time domain simulation with 7 degrees of freedom (7DOFs) of a TLP moored PA-WEC is conducted with the control force estimated using the trained models in regular waves and irregular waves.
A Study on Validation of Linear Seakeeping Codes With Benchmark Tank Tests for Container Ship and VLCC
Authors: Takeda Katsutoshi , Matsui Sadaoki , Sugimoto Kei 
Published: August 2024

Abstract
Direct load-structure analysis can apply ship responses through seakeeping analysis to structural strength assessment and has been put into practical use. To employ this method, it is imperative to validate the accuracy of the seakeeping code with experimental data. In this study, model ships for a very large container ship and a VLCC (Very Large Crude oil Carrier) were designed to acquire measured data of ship responses in tank tests. In the validation process of the seakeeping code, it is necessary to investigate the cause of differences in ship responses. Our initial focus is how to input the weight and KG (Vertical center of gravity from keel) distribution. We found that the difference of these distributions affects the variations in ship responses. Subsequently, a comparative study was carried out with two seakeeping codes based on the 3-dimensinal Green’s function method. The measured ship responses and numerical results by the codes were generally in good agreement. However, there were significant discrepancies in some responses. This was due to minor differences in a part of method in which the codes calculated hull girder sectional force, despite the same basic theory.
Development of Two-Phase Flow-Induced Vibration Predicting Method for a Piping System With Elbows
Authors: Komuro Yoshiteru , Nakanishi Hiroaki , Kondo Yoshiyuki , Takemoto Masashi , Hirota Kazuo , Matsumoto Shunsaku , Sugimura Tadashi , Honjo Shintaro 
Published: August 2024

Abstract
Gas-liquid intermittent two-phase flow in the piping system may cause piping vibration due to the repeating collision of liquid chunk onto the inner wall of elbow fittings. To design and monitor of piping system with elbows in Oil & Gas production plants or chemical plants, it is necessary to develop a prediction method for unsteady two-phase flow in the piping, vibration of the piping and the piping fatigue strength.
Several cases of unsteady two-phase flow Computational Fluid Dynamics (CFD) analysis were conducted to calculate excitation forces at each elbow of a jumper piping. In a slugging condition, the intermitted two-phase flow was simulated in CFD analysis and the frequency characteristics of fluid excitation force were obtained.
Conducting the vibration analysis, the stress at each section was evaluated and the maximum stress in a slugging velocity condition was larger than that in other velocity conditions such as bubbly flow condition and stratified flow condition. Fatigue analysis in frequency domain was carried out to estimate the lifetime of elbow fittings, using the stress response spectrum in each elbow estimated by the vibration analysis.
Through these analyses, it is confirmed that the developed analysis method can predict the two-phase flow and vibration characteristics which are qualitatively expected in advance.
Hydroelastic Analysis of Interconnected Modular Systems for Floating Offshore Solar Photovoltaic Use
Authors: Chen Yongqiang , Zhang Yifan , Ren Xiudi , Li Jun , Zhang Xiantao 
Published: August 2024

Abstract
An interconnected-modular system can be used as the floating foundation for offshore solar photovoltaic. The modular alone is a middle-hollow rectangular plate, where the hollow part sits the photovoltaic panel. A large number of modulars are interconnected to form a very large floating structure of huge hectares and a large length-to-thickness ratio, which makes its dynamic response a typical FSI problem. The Discrete Module Finite Element (DMFE) method is applied to the structure to calculate hydroelasticity under regular waves. The DMFE method first divides the structure into a certain number of macro-submodules with each of them treated as rigid bodies to perform a multi-rigid-body hydrodynamic analysis to obtain the hydrodynamic coefficients using the 3D potential flow theory. Each macro-submodule is treated as a lumped mass and the shell element is used to discretize the structure with the nodes being categorized into lumped masses, boundary nodes and inner nodes. The lumped-mass stiffness matrix is derived based on the sub-structure approach and matrix manipulations. Recovery of displacement response is given. Good agreement with the mode-superposition method verifies the current model.
Laserline SD® Seam Welded Super Duplex Umbilical Tubing for Up to 15 KSI DWP
Authors: Kim Yong-Joo , Melvin Tucker , Signorelli Rodrigo 
Published: August 2024

Abstract
The main objective of this paper is to present the product and process performance capabilities of seam-welded S32750 umbilical tubing for 10 KSI and 15 KSI DWP applications and discuss the specialized processes, project management, and documentation systems used for umbilical tube production. This paper also provides an overview of super duplex steel and sheet coil making, along with the manufacturing process for key seam welded tube, tube inspection, and testing. Actual technical data is presented and compared with typical industry requirements.
This paper addresses the relevant aspects of S32750 cold-rolled strip used for seam welded umbilical tubing. The requirements imposed by the criticality of the subsea umbilicals raise the bar on the steel manufacturer. From a chemical composition to meet the desired minimum pitting resistance equivalent, to the production of clean steel and mechanical properties in the final tube, all processes are essential to withstand the high-pressure environment, without compromising the fabricability and fatigue life which can be up to thirty years.
With the evolution of modern laser beam welding technology & highly specialized process monitoring and control systems, seam welded super duplex umbilical tube produced in compliance with API 17E, ASTM A789 and end user’s specific requirements has now gained a respectable record of proven performance. This paper also provides product attributes including dimensional data, mechanical properties, ferrite balance, corrosion, and fatigue performance for dynamic applications.
Design Considerations for Fuel Cell Systems Employed in Long-Endurance Autonomous Small-Sized Subsea Robots
Authors: Penga Željko , Xing Yihan , Bodner Merit , Berntzen Tor-Olav 
Published: August 2024

Abstract
Autonomous robots have the potential to significantly decrease operational costs associated with human operations and increase safety through the reduction of human errors. With the advancement in robotics today, many more are considering using autonomous subsea robots in various industries, such as fish farming, subsea oil and gas, ocean renewables and even subsea mineral mining. The ability to have long endurance, i.e., to operate for long periods without refuelling, is crucial to reap the benefits of robot autonomy better. Fuel cells, with their significantly higher energy storage capacity than lithium batteries, offer an attractive option to provide the long endurance required. Fuel cells have been successfully used in various land-based applications, such as cars and trains. However, to date, fuel cells have not been very much employed in underwater vehicles. Several subsea-related challenges arise when fuel cells are employed in subsea robots, which must be addressed. These include (i) underwater storage of hydrogen and oxygen, (ii) subsea-ambient environmental issues such as large hydrostatic pressures and cold ambient underwater conditions, (iii) dynamic manoeuvring actions by the robot that can cause large trim motions and (iv) fuel cell operations in a sealed container and with pure oxygen. This paper will discuss the most important design conditions that can arise when employing fuel cell systems for autonomous small-sized subsea robots with long endurance requirements.
Leveraging Digital Twins for Hydrogen Loss Mitigation in Large Scale Salt Cavern Hydrogen Storage
Authors: Yilmaz Ayse , O’Brien Sally , Thies Philipp , Das Prodip , Oterkus Erkan 
Published: August 2024

Abstract
As hydrogen continues to emerge as a key solution to decarbonise the global energy sector, interest in efficient storage solutions increases to meet rising energy demands and to ensure energy security. Large scale hydrogen storage salt caverns look to be a promising solution for hydrogen storage due to their ability to store large volumes of gas safely, as proven when storing natural gas in underground salt caverns. Hydrogen stored in underground salt caverns exhibits losses due to reasons such as gas migration, and the active chemistry they possess in addition to leaks due to damage caused by the cyclic loading on the cavern. Understanding the hydrogen loss pathways could help reduce financial losses and mitigate any safety risks imposed. Using SSE’s Aldbrough Hydrogen Pathfinder project, based in the UK Humber region as a case study, this paper aims to demonstrate how a digital twin can be utilised to evaluate and forecast hydrogen leaks by incorporating real time and historical data from sensors, geological information, and environmental factors to provide a holistic view of the cavern’s dynamics. This research aims to facilitate early detection of failures and highlight possible intervention mechanisms and strategies for underground salt cavern storage used for green hydrogen.