bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical Simulation of Chain-Reaction Implosions and Analysis of Different Implosion Beginning Positions
Authors: Shengxia Sun , Zhao Min 
Published: September 2023

Abstract
Hollow ceramic pressure hulls in the deep-sea underwater vehicles have potential risk of destructive chain-reaction implosions. A numerical simulation method for the chain-reaction implosions of multi-ceramic pressure hulls is developed. The underwater implosion in the ultra-high pressure is solved by the compressible multiphase flow theory. This method has been verified by the comparison with implosion experiments. The structure finite element method (FEM) is used to solve the response of ceramic pressure hull under implosion flow field loads and is combined with the failure criterion of ceramic materials as the judgment basis for inducing implosion. It is found that the pressure drop caused by the expansion wave generated by the implosion of the ceramic pressure hull triggers the implosion of the adjacent pressure hull. The implosion shock waves overlap each other, and generate shock wave pressure peaks larger than the implosion of a single pressure hull. Finally, three ceramic pressure hulls are arranged in a straight line, and the influence of different beginning positions of implosion on the flow field is also compared and analyzed.
Numerical Study on the Automatic Ballast Control of a Floating Dock
Authors: Wen Xueliang , Conde Alejandro Garcia , Zhang Jianan , Ong Muk Chen 
Published: September 2023

Abstract
Ballast control of a floating dock mainly relies on manual control, which requires highly skilled workers to master the ballast water system in several hours. Automatic control of the ballast water system can dramatically reduce the number of workers, improve operational efficiency, and increase safety during the vessel docking process. Motivated by this, this work studies the automatic ballast control of a floating dock and proposes a modified P-controller based on a numerical model for simulating the dynamic process of the floating dock’s operations. The numerical model includes a six-degree-of-freedom (6-DOF) model, a hydrostatic force model, a hydrodynamic force model and a hydraulic model. The hydrostatic force model is developed using the Archimedes law and a strip theory along the longitudinal direction. The hydrodynamic model is made based on the effects of added mass and dynamic damping. The hydraulic model is proposed to deal with the hydraulic calculation of the ballast water system. The present automatic ballast control is designed based on a proportional controller to control the valve opening angles when the pitch or roll angles are larger than corresponding threshold values. During the ballasting and de-ballasting operations without controllers, the roll angles of the dock reach value over 12°, which results from the asymmetric allocation of the ballast tanks. The present proportional controller can help stabilize the dock, i.e., keeping the pitch and roll angles within small allowable ranges of [−0.02°, 0.02°] and [−0.08°, 0.08°], respectively. The present automatic control will be further implemented in the vessel docking cases and can significantly improve the stability of the dock.
Anchoring System of Rigid Riser – Flowline Connection With Torpedo Piles
Authors: Novel Matthieu , Genzani Rachel C. , Solano Rafael F. , Jebali Adel , Scultori Marcio , Camilleri Florent , Valer Carlos , Mustiere Olivier 
Published: September 2023

Abstract
This paper discusses the innovative methodology for the anchoring of the rigid riser-flowline transition (TRF) in the Mero Field located in ultra-deep waters of the Santos Basin, offshore Brazil. The Mero Field is located in the Northwest area of the Libra block. Mero 1 project is composed by rigid MLP flowline systems which operate under high temperature and high inner pressure (HPHT) conditions, two different fluid types (oil and water alternating gas, i.e. WAG), permanent and transient flow regime with several predicted shutdown/start-up cycles during design life, unburied condition, with fully restrained anchoring system in the flowline at the well side and compliant in-line anchoring system (i.e. torpedo piles) at the TRF side interconnecting the SLWR. Suction piles connected to an in-line structure via mooring chain or in-line structure with pin piles are commonly used to anchor the rigid riser-flowline connection to the seabed. Both provide a robust anchoring solution with limited uncertainty with respect to the capability of the system to move under operating condition. The drawback of those solutions is that they often require procurement of heavy subsea structures and availability of large construction vessel for their installation. Despite the significant track record in the oil and gas industry for the use of torpedo piles for anchoring flexible and umbilical risers to avoid large displacement of the lines once installed or to enable design of subsea layout with tight curves, their use for anchoring of rigid riser-flowline connection was a first on Mero 1 project. The paper addresses the benefits and challenges associated with the use of torpedo piles for anchoring of rigid riser-flowline connections looking at every step of the process and in particular the following ones : definition of riser-flowline loading to be transferred to the anchoring system, behavior of anchoring system in operating condition (rendering of slack from embedded mooring chain, soil consolidation, requirement for pre-tensioning, etc.), flowline design limitation and requirement to avoid overloading of subsea equipment associated with the rigid line (pipeline end termination, suction pile, sleepers, etc.) and installation challenges to deliver an effective pipeline system.
Are Rogue Waves Predictable From Field Measurements?
Authors: Breunung Thomas , Balachandran Balakumar 
Published: September 2023

Abstract
Rogue waves, which are defined as waves with a wave height, or alternatively a crest height, exceeding the significant wave height by a certain factor, continue to endanger ships and offshore infrastructure. Hence, reliable rogue wave forecasting is of utmost importance to increase the safety for maritime operations. While the occurrence of rogue waves is widely acknowledged, their emergence remains unpredictable due to the lack of a well-accepted basis for explaining their occurrence. In fact, two popular mechanisms explaining the formation of rogue waves lead to considerably different conclusions about their predictability. On the one hand, a rogue wave could be formed by a superposition of wave trains with unknown phases. With this generation mechanism, rogue wave prediction is not viable. On the other hand, nonlinear focusing leading to the Benjamin-Feir instability gives rise to slowly developing rogue waves. Hence, this rogue wave formation could be detected with significant advance time. Given this background, there is an imperative need to address the basic question: Are rogue waves predictable?
In this article, the authors explore the predictability of rogue waves by constructing and parameterizing neural networks. The networks are trained on available buoy data, which allows not only for an assessment under the most realistic conditions but also for indicating the sufficiency of current ocean measurements for rogue wave prediction.
A Design and Numerical Study on a New Kelp Culture Facility
Authors: Lian Yushun , Shen Shutian , Zheng Jinhai , Boamah Samuel , Yim Solomon C. 
Published: September 2023

Abstract
As the market demand for seaweed products increases rapidly over the last few decades, farming of seaweed has become one of the most economical and environmentally friendly marine operations in aquaculture. Seaweed cultivation areas are primarily concentrated nearshore at present. However, with the expansion of aquaculture facilities, rapid coastal development and industrialization, available coastal area for aquaculture is decreasing sharply. This led to seaweed aquaculture being expanded to deep-water regions. In addition, the seaweed cultivation industry will likely transform from a labor-intensive industry to a technology and mechanization-intensive one. Based on the traditional raft culture facility, this paper develops a new design of a set of kelp culture facility focusing on improving their efficiency and stability. This facility is able to automatically adjust the submergence depth of kelp breeding ropes in different growth periods and dive into the water to withstand wind and waves at extreme sea conditions. The kelp breeding facilities are analyzed using the finite element software ANSYS AQWA. According to numerical analysis results, the dynamic response of aquaculture facilities under different sea conditions is discussed, and the effect of avoiding wind and waves after diving under extreme sea conditions is analyzed. It proves that this facility satisfies the requirements of offshore kelp cultivation, thus providing an essential reference for seaweed cultivation from nearshore to offshore areas.
Study on Cantilever Weighing Technology of Jackup
Authors: Yang Hankun , Wen Yan , Zhou Bo , Li Chunhui , Fan Shida , Yan Yongsi 
Published: September 2023

Abstract
The weight of cantilever beam is an essential part of the lightship weight of a jack-up drilling platform. Its weight and gravity center plays a very important role on the subsequent series of tests, such as inclining test, cantilever beam load test and so on. So how to get the weight and center accurately is a very important step during the construction of a jack-up rig. Based on a JU2000E construction project, this paper introduces the detail process of the whole weighing work of a cantilever beam. It includes the reasonable arrangement of lifting points and preliminary theoretical value of each lifting point, subsequent design of weighing system, the operation and monitor during the weighing process, and at last analyzing the weighing result of each weighing step and comparing the theoretical value and actual weighing result to prove that the arrangement of lifting points, the design of weighing system and site operation are all reasonable. Through the whole tracing of a cantilever beam weighing test, yard has got enough experience for the similar work of the future other jack-up drilling platforms and some other weighing works.
Hydroelastic Analysis of Offshore Floating Photovoltaic Based on Frequency-Domain Model
Authors: Shi Yongkang , Wei Yanji , Chen Zuogang 
Published: September 2023

Abstract
In this study, a frequency domain model for offshore floating photovoltaic (OFPV) hydroelastic response is developed by coupling the potential flow theory and the Euler Bernoulli beam theory. The OFPV was considered as modularized elastical plane in structural analysis while it was simplified as an dense array of rigid bodies in hydrodynamic analysis. The boundary element method open-source code Capytaine is used to solve the scattering and radiation problem. The third-order beam deflection equation is used to describe the continual response between the modules. The matrix method is used to model Euler-Bernoulli beams in structural mechanics, and the beam stiffness matrix is substituted into the structural dynamics equations. The proposed method was validated by comparing the results with the experimental and numerical benchmark. The hydroelastic response of a 300m × 300m OFPV was investigated using the proposed method. The results show that the response of the peripheral modules of OFPV is commonly large while the response of the internal modules may be amplified in specific sea conditions. It was suggested that the additional mitigation measures, such as proper connectors and/or wave dissipation systems, should be introduced into the OFPV design.
Modular Collision Avoidance Using Predictive Safety Filters
Authors: Vaaler Aksel , Robinson Haakon , Tengesdal Trym , Rasheed Adil 
Published: September 2023

Abstract
The number of maritime projects is increasing yearly, including offshore applications, underwater robotics for ocean condition monitoring, and autonomous ship transport. Many of these activities are safety-critical, making it essential to have a robust closed-loop control system that satisfies constraints arising from underlying physical limitations and safety aspects. However, this is often challenging to achieve for real-world systems. For example, autonomous ships at sea have non-linear and uncertain dynamics and are subject to numerous time-varying environmental disturbances such as waves, currents, and wind. There is growing interest in using machine learning-based approaches to adapt these systems to more complex scenarios. However, there is currently no standard framework to guarantee the safety and stability of such systems. Predictive safety filters have emerged recently as a valuable method for ensuring constraint satisfaction, even when unsafe control inputs are used. The safety filter approach leads to a modular separation of the problem, allowing the usage of arbitrary control policies in a task-agnostic way. In this work, a predictive safety filter is developed to ensure anti-grounding and ship collision avoidance for a small prototype ferry. The filter takes in a nominal input sequence from a potentially unsafe controller and solves an optimization problem to compute a minimal perturbation of the nominal control inputs, which adheres to physical and safety-related constraints. The system is validated by simulations for several realistic scenarios with map data from Trondheim, Norway. It is demonstrated that the predictive safety filter can avoid collisions with static and dynamic obstacles. The predictive safety filter approach is flexible and can be used to improve the robustness of various offshore applications, e.g. wind turbine stabilization, autonomous vessels, and marine robotics.
Evaluation of Wear and Damage on Large-Diameter Disc Cutters
Authors: Tytler Oluwafemi , Li Zijian , George Judith , Butt Stephen 
Published: September 2023

Abstract
The disc cutter is commonly used on cutter heads for drilling engineering, including tunnel boring, raise drilling, large diameter drilling, etc. Continuous use of the disc cutters over an extended penetrating time during drilling will lead to the disc cutter’s wear and damage, which then leads to reduced drilling performance, lost time, and ultimately higher economic cost. Therefore, it is significant to evaluate the development of the wear and damage of disc cutters in the drilling process and how they influence the overall drilling operation, thereby improving drilling performance prediction and cutter life assessments. In this study, the disc cutter wear and damage development were studied based on several ongoing field trials and research, and a quantitative method of measuring the wear and damaged of disc cutters was developed and has been used over the course of the research project.
Investigation of the Microstructure of Bismuth Alloy and its Interaction With Cement and Steel Casing
Authors: Manataki Andriani , Kontis Paraskevas , Sangesland Sigbjørn 
Published: September 2023

Abstract
Well-plugging and abandonment (P&A) of oil and gas wells involve the placement of barrier plugs at critical intervals in order to prevent leak paths between the reservoir and the surface. As per the Oil and Gas UK Well decommissioning Guidelines a barrier material, among all the prerequisites, should also provide an interface seal or bond, preventing flow around the barrier plug at the interfaces with adjacent casing steel or formation rock. So far, the most well-known barrier material is cement. It is well-qualified, but since it has also some limitations, other materials, such as bismuth-based alloys, have been investigated as an alternative to cement. This study focuses on the use of the eutectic BiSn alloy for well plugging, with 58% bismuth (Bi) and 42% tin (Sn). Like all bismuth-based alloys, this alloy expands on solidification, which is considered an important property for improving its sealing capability in a well. In addition, the microstructure resulting from the interactions between the BiSn alloy, cement, and steel casing, will affect the sealing performance. For this purpose, lab tests have been carried out using a small-scale test set-up. By scanning electron microscopy, various microstructures, in the BiSn alloy were observed and correlated with the interaction of the alloy with the steel casing and the presence of cement.
Innovative Crash Barrier Concepts to Prevent Ship Collisions With Wind Turbines
Authors: Otto William , Koldenhof Yvonne , Buchner Bas 
Published: September 2023

Abstract
The rapid development of offshore wind farms coincides with a growing amount of ship movements. This combination puts pressure on maritime safety, especially in the North Sea where space is limited. This risk was demonstrated at January 31st 2022, when bulk carrier Julietta D got adrift in a wind farm under construction. MARIN estimated that the annual probability of a collision between a ship and a wind turbine will be 1.5–2.5/year in 2030.
There are several mitigations possible to prevent ship-to-turbine collisions. As addition to the existing measures, MARIN investigated another innovative solution, a ‘crash barrier at sea’. A variety of barriers has been conceptualized by a team of industry experts. Out of this variety, three concepts were distilled for further analysis: A) a floating surface line, B) a mid-water buoy line and C) a pile supported net.
To test the three concepts, explorative scale model tests have been performed in MARIN’s Offshore Basin. As a reference case, a free drifting vessel similar to the Julietta D, in scaled storm conditions similar to January 31st 2022, was modelled. In general we can conclude based on these very initial experiments that collisions between drifting ships and offshore windturbines can in principle be prevented with these types of barriers, but also that they need further development, validation and evaluation with all partners involved.
Lumped-Mass Model to Represent the Installation Process of Subsea Equipment
Authors: Salvador Lopes Filipe , Fernandes Antonio Carlos , Sena Sales Junior Joel , Martins de Andrade Emerson , Machado João Paulo 
Published: September 2023

Abstract
The installation of subsea equipment is a complex process and due to that different installation methods were developed throughout the years, as the vertical installation method, which is this work’s focus. One of the main concerns when vertically lowering an equipment regards the tension on the installation cable, which might spike due to the high amplitudes of the equipment’s motions. If the tension on the cable exceeds its minimum break load the equipment will be lost. Therefore, this process must be properly simulated, to determine safe operation windows for installation. A numerical model to simulate this installation process was developed, using a lumped-mass model to represent the cable, and the six degrees of freedom of the equipment were considered during the simulations. Special attention was given to the possibility of snap loads occurrence, and the fourth-order Runge-Kutta method was used to solve the equations of motions of both the equipment and the cable, to provide the cable’s tension time series. The results obtained by the numerical model were compared to benchmark data and good adherence was found. It was observed that the cases in which the snap loads occur are indeed the ones in which the highest tension values happen, which indicates that these are the critical conditions for the installation operation.
What a Wave Buoy Actually Measures in 3D: Analysis of a Mild Sea State
Authors: Ding Yue , Taylor Paul H. , Zhao Wenhua , Dory Jean-Noel 
Published: September 2023

Abstract
Measurements of surface waves from oceanographic buoys have been regarded as the ‘ground truth’ for validation of sea-state prediction models, providing the basis for input to the design of offshore structures. The engineering practice is to produce wave statistics of vertical surface displacements over periods of years. However, a wave buoy can provide simultaneous time histories of its motion, one vertically and other two horizontally, giving the complete vector displacement field in time. We investigate the measured time histories of a wave buoy in three orthogonal directions, and explore the relationship between them, for a relatively benign, so typical, sea state. We adopt a NewWave-type analysis to investigate the average shape of the large events across the measured time histories. In combination with a conditioning analysis, we give a reciprocity relationship between the vertical displacement of the wave buoy and those in the horizontal plane. The relationship is of value, as it allows for the prediction of wave kinematics in the horizontal plane based on the vertical measurement only. We observe significant second-order components in the measured data in the horizontal directions and smaller contributions vertically. This data-driven analysis paves the way for wave-by-wave prediction and the active control of wave energy converters and floating wind turbines in engineering practice.
Scale Effects and Variability in Wave-in-Deck Type of Impact Loading, More Insights Into the Results of the BreaKin JIP
Authors: Scharnke Jule , Helder Joop 
Published: September 2023

Abstract
To quantify the loading due to breaking waves, model tests are currently the option of choice. However, it is suspected that scale effects lead to an overestimation of the prototype loading. As such, a typical question in impact load assessment is how conservative load measurements are. To understand how realistic model testing is in this respect, it is necessary to quantify scale effects in the measured loading due to breaking waves as well as to investigate to which extent entrapped air in the wave and during the wave impact is involved. To do so, the BreaKin Joint Industry Project was started in 2016. The objective of the BreaKin JIP was to get more insight into scale effects involved in wave-in-deck model tests and to take first steps towards linking wave kinematics with measured impact loads. During this JIP wave-in-deck model tests were carried out in MARIN’s Depressurized Wave Basin (DWB) at two scales (25 and 50) in atmospheric and depressurized condition. In previous work, a summary overview of these model test results was presented [1]. The current paper provides more in-depth insights into possible sources of scale effects involved in wave-in-deck type of loading, based on further analysis of the existing model test data. It includes a detailed review of a.o. local loads in correlation to the variability of measured (global) impact loads between repeat measurements.
Data Extraction Algorithm for Power and Speed Performance Analysis of Operating Vessel Based on Sliding Time Window
Authors: Wen Yiyan , Ma Ning , Shi Qiqi , Zhang Yanfei , Zhang Ziwen 
Published: September 2023

Abstract
Engine power and voyage speed performance analysis of operating vessel has strict requirements on the size and quality of operational data sets. A sliding time window and information entropy based algorithm for stable navigation interval extraction of operating vessels is proposed. Chebyshev’s inequality is introduced to clean the noisy data from the operating ship data and identify multiple feature parameters that are highly correlated with the engine power. By introducing a sliding time window, the period T of the sliding time window is determined using the trend of the autocorrelation coefficient between the features, and information entropy is introduced to analyse the multiple features to determine the stable operating interval of the main engine of the operating vessel. The results show this algorithm has strong adaptability and quality improvement effect for the operational big data filtering and extracting which is related to engine power and voyage speed analysis.