bluuebunny/crossref_metadata_2025_split huggingface dataset:
Maneuvering Prediction of a Surface Combatant in Calm Water With a CFD-Informed Mathematical Model
Authors: Aram Shawn , Wundrow David W. 
Published: August 2024

Abstract
A modular based mathematical model is adopted to predict the maneuvering performance of surface ships in calm water. The model coefficients are determined from a series of captive model simulations performed with computational fluid dynamics. The accuracy of the mathematical model is evaluated for turning circle and zig-zag maneuvers by comparison against free running model test data and high-fidelity simulations. Reasonable agreement in predicted maneuvering characteristics is obtained between the mathematical model and model test data; 3–5% averaged relative error in trajectory parameters for 25° and 35° turning circle and 20-20 zig-zag maneuvers. Sensitivity of the mathematical model to a set of propeller-rudder interaction parameters is demonstrated by 5–7% deviations about the mean in turning circle characteristics. Sensitivity of the zig-zag maneuver to the interaction parameters is less pronounced. Influence of the propeller side force on the maneuvering performance is examined and over 20% reduction in the steady turn diameter is found in absence of the side force. Importance of the propeller side force in the zig-zag maneuver is also described.
A Study on Hull Girder Longitudinal Strength Prediction by Adopting the Accurate Plate-Combination Model Based on Load-Shortening Curve
Authors: Yang Hee Yeong , Kim Do Kyun , Cho Nak Kyun , Li Shen 
Published: August 2024

Abstract
In this study, a plate combination model (PC model) was proposed for evaluating the longitudinal strength of the hull girder. There are representative models such as the PSC (Plate-stiffener combination model) and PSS (Plate-stiffener separation model) models for separating the structural components of the midship sections of hull girder. However, both the PSC and PSS models that are subjected to compressive loads have limitations in accurately considering local structural failure mechanisms. To overcome this limitation, the PC model introduced in this study separates all structural components comprising the hull into the concept of plates. Assumptions were made regarding the boundary conditions corresponding to the PC model to account for welding effects and collapse modes. Based on four assumed PC models, the longitudinal strength of the Dow 1/3 frigate model was compared. The results allowed for the selection of the optimised PC model. This study confirmed that CSR-H method could not adequately consider local collapse. The proposed method can be beneficial for the robust design of ship structures.
Numerical Study on Design Optimization of Tension Leg Platform for FOWT Based on Surrogate Model and Multi-Objective Evolutionary Algorithm
Authors: Park Hyo-Jin , Song Zhenhao , Nam Bo Woo , Ha Yoon-Jin , Kim Kyong-Hwan 
Published: August 2024

Abstract
In this study, the tension leg platform (TLP) for floating offshore wind turbines (FOWT) has been numerically optimized to minimize pitch motion and tendon tension responses using a surrogate model and the non-dominated sorting genetic algorithm II (NSGA-II). The target platform comprises a central circular column and three offset square columns with connecting pontoons. Firstly, the input design variables were selected via a sensitivity test, considering the geometrical parameters and specifications of the mooring tendons. Secondly, a large number of sample points were generated considering the constraints, and then the surrogate models were constructed based on the response surface method. Here, frequency-domain hydrodynamic analysis and fully-coupled time-domain simulations for the TLP-type FOWTs have been conducted with the WADAM and OpenFAST programs, respectively. Thirdly, by using the NSGA-II algorithm, the Pareto-optimal solutions for the multi-objective function were derived based on the surrogate model. Finally, the identified optimal solutions were verified by direct simulations, and their performances were compared with the initial design. Significant improvements can be found for the obtained optimized designs in terms of pitch motion or tendon tension responses. From the spectral analysis, it is evident that optimal solutions mainly reduce the wave frequency components of the pitch motion or tendon tension responses.
Analytical Buckling Solution for Steel-Concrete-Steel Sandwich Cylindrical Structures With Non-Uniform Thickness Under Varying External Pressure
Authors: Lin Hung-Chun , Collette Matthew D. 
Published: August 2024

Abstract
This study investigates an analytical global buckling solution for steel-concrete-steel sandwich cylinders, which are proposed to be used as the spar substructure for offshore floating wind turbines. Typically, the spar substructures are composed of steel cylinders with a certain amount of concrete as ballast weight. We propose to transform the conventional all-steel cylindrical spar into a steel-concrete-steel sandwich cylindrical spar, in which the spar structural strength can be potentially increased while providing the required weight. A preliminary estimation shows that the steel-concrete-steel structure can reduce the material cost by about 37% and increase the buckling strength by nearly 18% when comparing these with the original design while considering buckling only. However, the buckling strength evaluated in the preliminary study assumed the model with constant thickness under uniform external pressure, which is not a proper model for spar structures. To estimate the buckling strength realistically, this study will derive the analytical buckling solution for sandwich cylindrical structure with non-uniform thickness under varying external pressure. The classical laminated theory and Rayleigh-Ritz method with appropriate approximation displacement functions are used. The proposed solution is validated with commercial finite element software, ABAQUS, and the results show very good agreement with the simulation.
Numerical Investigation of Vortex-Induced Motions of a Scaled OC4 Floating Offshore Wind Turbine
Authors: Yang Yuxin , Liu Yuanchuan , Li Liang 
Published: August 2024

Abstract
Vortex-induced motion (VIM) is a critical issue for floating structures composed of one or more columns. This phenomenon can excite large oscillatory motions on floating structures, which can severely affect the stability of the structure and the fatigue life of mooring lines. In the present work, the VIM of the OC4 semi-submersible floating offshore wind turbine (FOWT) platform is studied numerically over a wide range of flow velocities by using an open-source Computational Fluid Dynamics (CFD) toolbox OpenFOAM. Comparisons are made between results for models with and without the connecting structures, including delta pontoon and cross braces, to assess their impacts on the platform VIM and the effect the yaw motion is investigated. Results show that the “lock-in” phenomenon in the transverse direction lies within the range of 8 ≤ Vr ≤ 12. By including the connecting structures in modelling the FOWT platform, its transverse motion amplitude is significantly reduced. Analysis reveals that the connecting structures exert considerable negative work on the platform motions and thus effectively mitigate the VIM phenomenon. Meanwhile, when the yaw motion is considered, large motion amplitude is excited in the transverse direction even at Vr ≥ 18, clearly indicating the coupling effects between the transverse and yaw motions. This work will contribute to the understanding of motion responses of FOWTs subjected to environmental loads from current.
Experiment Study of Critical Dynamic Loads for Stiffened Panels Under Axial Impact
Authors: Shi Guijie , Wang Deyu 
Published: August 2024

Abstract
In an actual seagoing environment, marine structures typically suffer from impact load actions such as bow slamming, ship-ice interactions, and ship-ship collisions. At extreme impact loads, dynamical buckling occurs in the stiffened panels, which is different from the buckling failure in static conditions. It is necessary to investigate the dynamical buckling criteria and failure modes by using experimental methods. In this paper, two sets of marine stiffened panels are designed to separately represent the first buckling on the plating and the stiffener web. Five models are fabricated for each stiffened panel. A drop hammer platform is used and an axial impact load with a series of initial velocities for the hammer is applied at the end of the stiffened panel. The dynamic buckling state is obtained based on the measurement of impact load and the panel deformation. Then, a new evaluation criterion is proposed to predict the critical load for dynamic buckling of the stiffened panels. The predicted critical state is consistent with the changing state of the failure mode for the stiffened panels. The conclusions can be used as a guide for the dynamic buckling evaluation in ship design.
Performance Evaluation of Different Control Algorithms for Torpedo-Shaped AUVs
Authors: Balasubramaniyam Shankruth , Umashankar Shriram , Gurudev Gowsik , Ramanujam Madhavnambi , Somayajula Abhilash , Venkatachalam Sriram 
Published: August 2024

Abstract
This paper compares Linear Quadratic Regulator (LQR) and Proportional Integrative Derivative (PID) control algorithms implemented in an in-house built Autonomous Underwater Vehicle (AUV). The AUV has actuators to control five degrees of freedom and features a non-linear dynamics model established through a Python-based simulation environment. Path following is achieved by employing the Line-of-Sight (LOS) and fully actuated path-following guidance law. The evaluation of the control algorithms is based on the trade-off between effort, endurance, time taken to reach the intended path, overshoot and steady-state error.
Extremum Seeking Control Implementation for Drilling Efficiency
Authors: Ikhlef Mohammed Amine , Bekkevik Sindre , Sahebi Hamed , Gravdal Jan Einar , Sui Dan 
Published: August 2024

Abstract
In the continuously changing environment of drilling operations, the optimization of the Rate of Penetration (ROP) holds significant importance in improving efficiency and minimizing operational expenses. This study introduces a new methodology, referred to as Extremum Seeking Control (ESC) with the aim of implementing sophisticated control and optimization methodologies for real time ROP or mechanical specific energy (MSE) in drilling.
The ESC algorithm is a real-time adaptive control method that does not rely on a model and is capable of adjusting parameters in the presence of unknown system dynamics and mappings between control parameters and an objective function. Extremum searching can be employed as a methodology for addressing static optimization problems and optimizing parameters inside dynamic systems. In this work, this control algorithm is utilized to dynamically modify drilling parameters in real-time. By continuously seeking the optimal combination of factors such as weight on bit (WOB), it enables drilling engineers to maximize ROP while ensuring drilling safety and equipment integrity. This strategy signifies a fundamental change from traditional procedures by providing high accuracy and flexibility in the control of ROP. Moreover, this research examines the application oWith the growing complexity of drilling operations, the incorporation of ESC emerges as a potentially viable approach to address the industry’s need for enhanced efficiency and cost-effectiveness.
Wave Dynamics Run-Up Modelling: Machine Learning Approach
Authors: Vileti Vinicius L. , Ersdal Svein 
Published: August 2024

Abstract
This study proposes an alternative approach to predict wave elevation near multi-column semi-submersible structures by applying machine-learning methods from experimental data.
The most common approach to this problem is to apply linear potential theory numerical programs to calculate the wave elevation close to such marine structures. However, in some cases, the assumptions for the potential theory are no longer valid, leading to a deviation from model test results.
Another possible approach is to solve Navier Stokes Equations Numerically (CFD), which poses a challenge regarding computational power for this kind of stochastic analysis.
This paper details a procedure to apply machine learning to enhance the results by combining potential theory and experimental results for future predictions. Aker Solutions has performed experimental tests with a TLP (Tension Leg Platform) shaped hull under waves while measuring wave elevation on several points around it. These experimental data were treated and combined with potential theory results to compose a machine-learning prediction model.
A frequency domain model was applied, where the experiment data is converted into the frequency domain and combined with the Potential Theory results to train the machine learning model.
Results show that the machine learning model improves the results for wave elevations when closer to the hull, as those are the cases where the potential theory deviates more. This approach can also be applied to similar problems, such as wave loading and vessel motions.
Influence of Underlying Currents on the Performance of a Taut-Moored Point-Absorber WEC: an Investigation Via High-End Numerical Tools
Authors: Capasso Salvatore , Tagliafierro Bonaventura , Göteman Malin , Martínez-Estévez Iván , Domínguez José M. , Altomare Corrado , Gómez-Gesteira Moncho , Crespo Alejandro J. C. , Viccione Giacomo 
Published: August 2024

Abstract
Site-specific environmental conditions in targeted areas for offshore renewable energy deployment often feature underlying currents. The effects of the latter on wave parameters and overall hydrodynamics modifies the behavior of light offshore structures, such as wave energy converters (WEC), with unforeseen alteration of power yield and structural loads. To address such effects on a taut-moored point-absorber — potentially susceptible to wave and current motion — the high-end numerical framework of DualSPHysics is used, as it leverages the flexibility of the Lagrangian Smoothed Particle Hydrodynamics (SPH) method for simulating fluid-structure interaction and external libraries to take on multibody problem posed by power take-off (PTO) and moored connections. A dedicated numerical wave tank capable of reproducing regular waves propagating over steady uniform currents is used to numerically test the Uppsala University WEC (UUWEC), which consists of a buoy connected to a linear PTO. Clear influence of the current traits is visible in the results regarding the point-absorber motion, power output, and anchoring tension. Remarkably, the sole presence of current can hamper the harvesting capabilities of the device, up to different extents depending on its intensity and relative direction with respect to the wave propagation. Tension patterns, instead, are found to be almost linearly sensitive to current intensity and direction, with beneficial effects produced by opposing currents and vice-versa.
Performance of Wave Absorbing Calculation and Verification for Floating Breakwater
Authors: Ni Xinyun , Wang Qibin , Yu Jun , Ding Jun , Wei Ziyang , Xie Chunmei , Chen Ying , Xu Lingyun , Cheng Xiaoming 
Published: August 2024

Abstract
There are two types of breakwater including fixed and floating. The fixed breakwater is usually used in shallow water sea area, not adapted to deep water area. In deep water area, the floating breakwater is an important type of marine equipment which can improve the work environment conditions effectively. In the course of design for breakwater, the motion responses and wave absorbing performance should be focused importantly. Especially, wave absorbing ability is a key factor for evaluating the performance of breakwater. In this paper, taking the double cylindrical floating breakwater as the research object, the in-house three-dimensional hydroelasticity software THAFTS is used to calculate the motion responses and wave absorbing coefficients of floating breakwater with two different character length, and the effects of length have been analyzed. At the same time, the wave absorbing coefficients at the monitoring points same with model test under different wave period are calculated and compared with model test results. Through the comparison, the calculation results have a good agreement with the model test results, and the breakwater has a good wave absorbing performance when the wave period is less than 6s. The research here offer the reference for further optimization of floating breakwater. And the self-developed software THAFTS can play an important role in performance prediction.
Advancing the Modelica™ Ocean Engineering Toolbox With the Capability to Generate Accurate Wave Excitation Forces
Authors: Menon Ajay , Haider Ali Shahbaz , Bubbar Kush 
Published: August 2024

Abstract
The Ocean Engineering Toolbox (OET) is an open-source, Modelica™ compliant symbolic library capable of simulating the dynamic motions of floating bodies subject to polychromatic, unidirectional waves. This paper presents recent advancements in the OET: (1) the development of custom components to represent the frequency-dependent wave excitation force and (2) significant improvements in the toolbox’s computational performance. While the Modelica language can represent complex cyber-physical systems efficiently, the primary challenges with modeling wave-induced floating bodies are (1) non-compatibility with frequency-dependent variables, (2) lack of hydrodynamic components in the Modelica Standard Library (MSL), and (3) integration with the previous version of the OETv0.1. In the time-domain implementation, surface elevation profiles can now be generated for regular and irregular waves, with three spectral options for polychromatic seas: Pierson-Moskowitz (PM), Bretschneider, and Joint North Sea Wave Project (JONSWAP). Hydrodynamics coefficients are imported using a MATLAB script to process the output from Boundary Element Method (BEM) codes. A novel symbolic implementation of spectral decomposition and interpolation is presented in this work to generate the frequency-dependent excitation force in Modelica. Results from the OET are compared against data generated from WEC-Sim, validating both the wave excitation force and the corresponding system dynamic response for a floating point absorber in heave. These developments lead to superior simulation accuracy and computational performance while expanding the hydrodynamic modeling capabilities of Modelica.
High-Fidelity Simulation Platform for Autonomous Fish Net-Pen Visual Inspection With Unmanned Underwater Vehicles in Offshore Aquaculture
Authors: Tun Thein Than , Huang Loulin , Preece Mark Anthony 
Published: August 2024

Abstract
The importance of high-fidelity simulation in the deployment of Unmanned Underwater Vehicles (UUVs) in offshore aquaculture is evident, driven by a range of crucial factors such as safe deployment in challenging working environments. Such simulations enable thorough testing and refinement of UUV behavior, thereby mitigating safety concerns associated with human workforce exposure to risk. Additionally, the intricate preparations for real-world field trials involving multiple stakeholders require thorough planning. High-fidelity simulations serve a pivotal role as an informed decision-making tool in a cost-efficient way in aligning these diverse stakeholders and in pre-validating the advantages and challenges associated with UUV deployment in uncertain and demanding offshore aquaculture environments. In this paper, a number of existing simulation platforms are reported and using one of them which is built on the Robot Operating System (ROS) in Python, namely UUV simulator, an autonomous fish net-pen visual inspection with the BlueROV2 Heavy Configuration for the Blue Endeavour project (an upcoming first offshore aquaculture firm in New Zealand) of the New Zealand King Salmon company was demonstrated as a use-case study.
Systematic Study on the Drag Reduction Performance of a Microstructure Inspired by Pufferfish
Authors: Hu Shoujun , Li Ruoxin , Yu Kai 
Published: August 2024

Abstract
Due to the nature of migration, pufferfish has excellent underwater drag reduction ability. Apart from its streamline body, some studies showed that the microstructures on its body could also contribute to the drag reduction. In this work, the effects of the microstructure on the surface of pufferfish are numerically simulated. The microstructure features of the pufferfish surface are extracted and simplified. Orthogonal experiments on three levels of height, inclination and spacing of the microstructures are carried out. The simulation scheme and calculation results are verified. The results show that the height of microstructure is the main geometrical parameter affecting its drag reduction performance, and in a certain range, the drag reduction performance of the microstructure increases with the increase of height. The optimal combination of the microstructure for drag reduction is 0.05mm in height, 67.5° in inclination, 0.4mm in spacing.
Fluid-Structure Interaction Analysis of Crescent-Shaped Wingsails
Authors: Zhu Heng , Chernoray Valery , Ringsberg Jonas W. , Yao Hua-Dong , Ramne Bengt 
Published: August 2024

Abstract
The use of wind-assisted ship propulsion is regarded as one of the effective ways to reduce greenhouse gas emissions. This study combines wind tunnel experiments and advanced numerical simulations to investigate the model-scale effects and fluid-structure interaction (FSI) of a wingsail with a crescent-shaped profile. First, a wind tunnel test is carried out to study the aerodynamic loads and flutter of the wingsail. Next, a numerical method for analyzing FSI, fully coupling computational fluid dynamics and finite element analysis, is established. By comparing the experimental and numerical results, the model-scale effect that has an influence on the accuracy of prediction, e.g., laminar-turbulent transition, is discussed. Then, a full-scale FSI simulation based on a simplified solid model was performed to study the flutter and its influence on the propulsive performance. The results indicate that the crescent-shaped profile causes notable periodic oscillations due to strong flow separation, significantly affecting propulsive performance. These insights are crucial for the design and optimization of wingsail structures in enhancing wind-assisted ship propulsion.