bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mooring System ULS Analysis Based on Empirical QTFs of Wave Drift Loads
Authors: Fonseca Nuno , Tahchiev Galin , Rogne Øyvind Ygre 
Published: August 2024

Abstract
Ultimate limit state (ULS) analysis for the mooring system of floating structures is performed for the most severe seastate conditions. For many structures, horizontal wave drift loads and related slow drift oscillations are simultaneously the environmental component with the largest contribution to the extreme line loads and the component with the largest uncertainty in numerical predictions. It is acknowledged that state-of-the-art hydrodynamic design analysis tools, namely radiation/diffraction potential flow codes, tend to underestimate wave drift loads in severe seastates for floating structures with large waterplane area. This is often the case for floating, production, storage and offloading vessels (FPSOs).
While correction methods have been proposed recently, this paper presents a different approach. The proposal is to use empirical quadratic transfer functions (QTFs) of horizontal wave drift loads directly in the mooring analysis time domain simulations. The empirical QTFs are identified from model test data in severe seastates with current by a second order signal analysis technique known as cross bi-spectral analysis.
The paper describes the method and validates with a case study consisting of a FPSO operating in the North Sea. Standard hydrodynamic analysis tools provide correct first order motions in extreme seastates with current, as compared to model test data. However, it significantly underestimates the wave drift loads and the related low frequency (LF) horizontal vessel motions. Use of empirical QTFs significantly improve the LF motion predictions, both in terms of mean offset and in terms of LF standard deviation and energy spectra. Furthermore, the limitations of Newman’s approximation versus use of full QTFs are highlighted. The later provides a much better phasing of the LF motions and also better prediction of the LF peaks.
Optimization of CO2 Water-Gas Alternating Injection-Production Parameters in Low Permeability Reservoirs
Authors: Tian Leng , Huang Wen-kui , Tang Chuan-yi , Tian Hui , Peng Long , Li Mingliang 
Published: August 2024

Abstract
The reservoir heterogeneity of low permeability reservoir is strong, and it is easy to form fingering phenomenon in the process of continuous water injection or gas injection development. The use of CO2 water-gas alternation technology can not only make full use of the advantages of CO2 flooding, but also effectively reduce the fingering phenomenon and improve the development effect. However, due to the unreasonable injection rate, slug size, gas-water ratio and other parameters, the CO2 breakthrough in the production well is too early or the expected development effect is not achieved. Therefore, it is necessary to study the optimization of CO2 water-gas alternating injection-production parameters in low permeability reservoirs. Based on the actual formation and fluid characteristics of A oilfield, the reservoir numerical simulation method was used to optimize the injection-production parameters of CO2 water-gas alternating flooding in this area. The results show that the development effect is the best when the water injection is first followed by gas injection, the gas injection rate is 0.08 PV / year, the water-gas ratio is 1:2, and the alternating period is 3 months. The recovery rate is 42.15 %. The scheme is 13.67 % higher than the pure water flooding scheme and 4.89 % higher than the pure gas flooding. The research results have certain reference significance for improving the mining effect of A oilfield.
Physics-Informed Neural Networks for Flow-Induced Vibration Prediction of a Subsea Pipeline
Authors: Yin Guang , Janocha Marek Jan , Ong Muk Chen 
Published: August 2024

Abstract
Flow-induced vibration (FIV) is a common phenomenon in ocean engineering for subsea structures with circular-shaped cross sections. A large amount of computational resources or experimental efforts are required to predict or measure the complicated motions and flow field surrounding a circular cylinder undergoing VIV. Physics-informed neural networks (PINNs) are powerful deep learning techniques for solving governing partial differential equations (PDEs) of dynamic systems as an alternative to complex numerical methods. In the present study, a framework is built employing PINNs for solving the Navier-Stokes equations to predict flows past an FIV cylinder by using sparsely distributed spatiotemporal data inside the domain. The training process involves minimizing the supervised loss of flow data at these sparse points and the residuals of the governing PDEs. For the training of the PINN model, a moving frame around an FIV cylinder is used to collect the training flow data from two-dimensional direct numerical simulation results at a low Reynolds number. The structural displacements of the cylinder are also implemented in the residuals of the equations of the developed PINN. The performance of the PINN is evaluated by comparing the predicted contours of the surrounding flow velocities with the training data. The hydrodynamic forces prediction is achieved using the PINN-obtained flow field predictions combined with the force partitioning method.
Comparative Study of Mooring Type Effect On Offloading Operability of Near-Shore FLNG With Side-By-Side Moored LNG Carrier in Shallow Water Depth
Authors: Kim Mun Sung , Kim Bo Hee , Yuck Rae Hyoung , Lee Yong Chul , Heo Jae Kyung 
Published: August 2024

Abstract
Recently, the FLNG projects have been developed for the LNG production at near shore field with shallow water depth. For the permanent mooring of FLNG in this field, several mooring types such as Jetty, Yoke, fixed structure (strut) and spread mooring are considered up to now. In the development of near shore (NS) FLNG projects, one of the key issue is safe ship-to-ship (STS) offloading operation for the transfer of LNG cargo to shuttle LNG carrier through marine loading arm (MLA) with side-by-side (SBS) mooring arrangement. In this paper, a numerical comparison of the side-by-side offloading operability of NS FLNG with the different mooring system is performed for the near shore site.
In order to perform the comparison, two permanent mooring types for the fixed structure (strut) mooring and spread mooring system are designed for NS FLNG. For comprehensive SBS offloading operation comparison, numerical two-body motion simulation is carried out in frequency- and time-domain. As an environmental condition, the benign sea, such as North America or East/South Asia wind, wave and current data is applied for the study.
Based on numerical simulation results, offloading operability of near shore FLNG during STS operation, dynamic loads acting on the mooring lines and fenders as well as relative motion are compared. Generally, the maximum line tension, fender force and relative motions are under the limit criteria, however, the responses of SBS line tension are not similar in both cases. Throughout the comparative study, it is found that the offloading operability of NS FLNG is affected by the different mooring system types. In addition, there are needs of further study for precise hydrodynamic analysis for damping in sloped shallow water depth.
Efficient Design of Floating Offshore Wind Turbines
Authors: Sablok Anil , Koo Bonjun , Miliante Thiago 
Published: August 2024

Abstract
The offshore wind industry trend is towards larger floating wind turbines to lower the Levelized Cost of Energy (LCOE). It is more difficult to design, install, and maintain them. The challenges related to a large floating wind turbine design and analysis are to model and analyze in the time domain the fully coupled system that includes flexible turbine tower dynamics, rotor dynamics, and floating platform dynamics. Floating Offshore Wind Turbine (FOWT) analysis and design require more design load cases than oil and gas platforms due to the various wind turbine operating conditions. This takes a very long time and extends the engineering schedule significantly. To reduce time and make the design process efficient and accurate, a more automated design process and tools are required along with using High Performance Computing (HPC) resources.
The improved processes and tools developed for oil and gas production platforms have been improved and adapted to the design and analysis of FOWT for quick investigation of different design parameters and select an optimum design satisfying all the design criteria upfront and minimizing required design iterations which are normally not possible in a FOWT project due to long analysis and design time. Global response and improved structural analysis methodology compatible with HPC are used for efficient analysis and design of FOWT and associated mooring. The results show that the design cycle time is not only significantly reduced, but the estimation of full lifetime estimation of platform performance and energy production is more accurate. The tools developed can also be used as a digital twin for quick estimation of performance and conditioning.
A Novel Drag Anchor Design for Enhanced Penetrability and Holding Capacity
Authors: Zhang Youhu , Li Shuzhao , Wang Xiangyu , Wu Chuheng , Guo Peng , Lei Di 
Published: August 2024

Abstract
Drag anchor is an appealing anchoring solution for a variety of floating structures due to its high holding capacity ratios and relatively low cost for installation. The holding capacity of a drag anchor is to a large extent dictated by the penetration depth achieved during installation. In hard soils, such as sand and stiff clay, the penetration depth of the drag anchor is often limited to about one fluke length due to the large soil resistance encountered on the shank. In this paper, a novel single-shank anchor design that greatly reduces the soil resistance on the shank is proposed in the hope of improving its penetration depth and consequently the holding capacity. To verify the design assumption, a series of three-dimensional finite element simulations using the Coupled Eulerian-Lagrangian method are carried out. The results of the analyses in both sand and clay soils demonstrate superior penetrability and considerably improved holding capacity of the proposed single-shank anchor design.
Numerical Investigation on the Hydrodynamic Performance of High-Speed Displacement Vessel With Transom Hull Vane
Authors: Soma Gouthama Chary , R. Vijayakumar 
Published: August 2024

Abstract
A numerical analysis of the hydrodynamic performance of high-speed displacement vessels with and without Hull Vane (HV) is presented in the paper. A Hull Vane is an energy-saving device that is transversely fastened to the vessel’s transom bottom. The pressure differential is the primary reason for the vessel’s decreased pressure drag and trim. The Finite Volume approach employing a standard mesh was used to analyze the hull model utilizing a Hull Vane with various spans. Heave and pitch are the two degrees of freedom taken into account. The high-speed displacement vessel with and without a Hull Vane is subjected to model tests in calm water in the Department of Ocean Engineering’s current towing tank facility at the Indian Institute of Technology, Madras. The effects of span (Length of the HV has been discussed in this paper. The vessel’s performance is significantly influenced by the length of the Hull Vane and limited condition for span has been obtained. The study demonstrates a greater trim reduction due to the lift force produced by the hull vane at the stern of the vessel. The overall resistance coefficient has been decreased to 7%.
A Hybrid Deep Learning Approach to Predict Dynamic Mooring Tension of a Wave Energy Converter
Authors: Xu Sheng , Wang Shan , Guedes Soares Carlos 
Published: August 2024

Abstract
Enhancing the precision of short-term mooring tension prediction holds the key to bolstering safety measures within marine operations. In this study, a hybrid model which takes the advantages of convolutional neural networks (CNN) and gated recurrent units (GRU) is developed to predict dynamic mooring tension time series of a wave energy converter. The datasets used to train the hybrid model were collected from model tests conducted in a wave flume. The hybrid model is trained using motion responses of a wave energy converter. The study explores and discusses the impact of various factors on the performance of the hybrid GRU model, including the number of neurons, the choice of optimizer, and the number of dully connected layers. Optimal model parameters are determined through an assessment of error indexes. Once the optimum GRU model is determined, a hybrid model which consists of the CNN and the optimum model is proposed for predicting mooring tensions. To evaluate the effectiveness of the hybrid model, a comparison is made between its performance in dynamic mooring tension prediction and that of GRU. This research offers highlights the substantial potential of the proposed method in predicting mooring tensions for other offshore floating structures.
The SPAR Model: A New Paradigm for Multivariate Extremes. Application to Joint Distributions of Metocean Variables
Authors: Mackay E. B. L. , Murphy-Barltrop C. J. R. , Jonathan P. 
Published: August 2024

Abstract
This paper presents the application of a new multivariate extreme value model for the estimation of metocean variables. The model requires fewer assumptions about the forms of the margins and dependence structure compared to existing approaches, and provides a flexible and rigorous framework for modelling multi-variate extremes. The method involves a transformation of variables to polar coordinates. The tail of the radial variable is then modelled using the generalised Pareto distribution, with parameters conditional on angle, providing a natural extension of uni-variate theory to multivariate problems. The resulting model is referred to as the semi-parametric angular-radial (SPAR) model. We consider the estimation of the joint distributions of (1) wave height and wave period, and (2) wave height and wind speed. We show that the SPAR model provides a good fit to the observations in terms of both the marginal distributions and dependence structures. The use of the SPAR model for estimating long-term extreme responses of offshore structures is discussed, using some simple response functions for floating structures and an offshore wind turbine with monopile foundation. We show that the SPAR model is able to accurately reproduce response distributions, and provides a realistic quantification of uncertainty.
Comprehensive Evaluation and Optimization of Multilateral-Well Aquifer Thermal Energy Storage Systems
Authors: Li Shuang , Song Xianzhi , Wang Gaosheng , Yi Junlin 
Published: August 2024

Abstract
Aquifer thermal energy storage (ATES) has proven to be an effective way to mitigate energy production and supply issues. Drilling branching holes from traditional vertical wells can enhance the injection and production capacity of the ATES system. There are many influencing parameters and evaluation indexes of ATES system with multilateral wells. It is necessary to conduct a comprehensive analysis of the system performance. Therefore, a three-dimensional numerical model of fluid flow and heat transfer for the multilateral-well ATES system is built with COMSOL and verified with experimental data. Then, the multilevel orthogonal tests are carried out to analyze 6 factors with 5 values. The grey correlation method is used to compare the influence of key parameters on energy utilization coefficient and coefficient of performance (COP) of hot well. The results show that there are great differences in the order of parameter correlation degree under different indicators. So this study determines the weights of four evaluation indicators based on the Analytic Hierarchy Process (AHP). The optimal scheme is selected from 25 orthogonal experiments by fuzzy comprehensive evaluation. The optimization method established in this study can comprehensively evaluate the operating performance of multilateral-well ATES system and provide reference for its reasonable design.
Round-Trip Between Two Ports: Autonomous Operation of a Container Feeder Vessel
Authors: Cozijn J. L. , de Kruif B. J. , van Daalen E. F. G. , Iavicoli G. 
Published: August 2024

Abstract
MARIN is a partner in the EU funded research project MOSES (“AutoMated Vessels and Supply Chain Optimisation for Sustainable Short SEa Shipping”). MARIN has designed an innovative container feeder vessel, including solutions for zero emission propulsion. The autonomous operation of this vessel was investigated using a two-step approach.
First, a time-domain simulation model of the ship was made. Algorithms for vehicle control and autonomous operation were designed, implemented and tested. The time-domain model included a large sea area with two ports (Mykonos and Piraeus) and an accurate model of the container feeder vessel, including all necessary sensors and actuators. The round-trip between two ports consists of several different sections, such as docking and undocking, port manoeuvring and transit in open sea. Each section required different capabilities of the ship, which were defined using operational states in a state machine.
Second, the simulated ship was replaced by a scale 1:17 physical model, while the software for autonomous control remained the same. The model was completely wireless, with its own on-board power supply. Measured signals were transferred to the basin carriage using a Wi-Fi connection. The scale model, during one of the experiments in the basin, is shown in the photograph in Figure 1. In the model basin, a schematic port was modelled, as the start and end point of its journeys. The ship model was able to successfully perform round-trips through the basin, including autonomous docking and undocking.
Retrofitting Propeller Procedure for a Hydrogen Fueled Offshore Support Vessel
Authors: Tadros Mina , Xu Yunxin , Das Tapas K. , Shi Weichao 
Published: August 2024

Abstract
With new technologies bringing drastic changes to ship design, existing vessels are facing challenges to accommodate the revolutionary changes for a cleaner future. This paper presents the retrofitting study applied to the propulsion system of an offshore support vessel to be fueled by hydrogen, which shows suitability to operate coastal vessels.
Redesign of the vessel’s propulsion system has been conducted. First, the ship resistance is computed using the computational fluid dynamics (CFD) method. The results show a good agreement with the data exported from the experimental tests and the computed results from empirical formulas. Then, based on the resistance calculation, the propeller is redesigned to improve its performance without any modifications in the main prime mover and the gearbox. The results show a significant improvement in the propeller performance as well as ship operating conditions compared to the existing propeller.
The findings of this study contribute to the ongoing TransShip II project, which is applied to the Prince Madog research vessel to achieve zero emission levels in the maritime industry. This kind of retrofitting procedure will promote energy-efficient designs in further ships to reduce the amount of fuel consumption and exhaust emissions compared to the performance of the existing vessels.
Level of Service Evaluation Method for Waterways Based on Vessel Displacement
Authors: Liu Yihua , Wang Menglin , Li Mengting 
Published: August 2024

Abstract
The level of service (LOS) of a waterway is an important evaluation index to measure the planning effect and operation quality of waterway facilities. However, the research on LOS from the perspective of vessel characteristics and vessel traffic flow operating conditions has yet to be mentioned. In this paper, based on vessel displacement, proposing a method to use the theory of redefined parameters of water traffic flow characteristics to analyze the data of ship navigation information of the waterway, establishing an evaluation system using vessel displacement as an indicator, and to formulate a waterway service level evaluation standard for the water transport version. The method was applied to process and analyze the data in the waters of the NanCao Channel of the Yangtze River, the results show that the method can more accurately determine LOS and truly reflect the operation quality of the waterway infrastructure. Therefore, the method can not only guide vessel drivers to choose areas with higher comfort for navigation but also provide a decision-making basis and critical parameters for the waterway management department.
Effects of Jump Rope Lessons on Physical Skills, Inhibitory Control, and Perceived Enjoyment of Elementary Students
Authors: Woodard Kaylee F. , Chen YuChun 
Published: August 2024

Purpose: This research examined the effects of a freestyle jump rope unit on students’ jump rope proficiency, agility, balance, inhibitory control, physical activity level, and perceived enjoyment. Method: One hundred and nine third and fourth graders were randomly assigned to the video-led (VID), teacher-led (TEA), or control group. A 30-s jump test, crisscross test, shuttle run, balance test, and Stroop test were conducted before and after the intervention. Physical activity level and perceived enjoyment were also assessed. Results: Repeated-measures analysis of covariance revealed that all groups showed significant improvement on the 30-s jump test, the VID and TEA groups improved on the crisscross test, and the TEA group ran significantly faster on the shuttle run following the intervention. The VID and TEA groups showed significantly greater inhibitory control after the intervention. Students in all groups were less active in the last two lessons compared with previous lessons. Perceived enjoyment was higher after Lesson 2 than Lesson 8. Discussion/Conclusion: This research indicated that implementing a freestyle jump rope unit in PE can elicit various benefits for children aged 8–9 years. Additionally, using a teacher-led instructional method may yield advantages beyond video-based instruction.