bluuebunny/crossref_metadata_2025_split huggingface dataset:
Meshfree Model for Porous Seabed Response Under Combined Earthquake and Random Wave Loading
Authors: Han Shuang , Zhang Jisheng , Tsai ChiaCheng , Jeng Dong-Sheng 
Published: August 2024

Abstract
In the context of offshore structure design, the consideration of earthquake and wave loadings is paramount due to their pivotal role as natural dynamic forces. These dynamic forces can induce vibrations in the pore water pressure, thereby precipitating seabed instability. However, the investigations of the earthquake-induced seabed behaviour are limited. Furthermore, contemporary studies on seismic seabed response often neglect the concurrent impact of ocean waves. Previous research predominantly relies on conventional mesh-based methods, such as the finite element method. To address the limitations inherent in such methods, such as computational time and mathematical complexity, this study employs a meshfree method based on the “u – p” approximation. The research assesses soil response under the Japan 311 earthquake and random wave loading in both time and frequency domains. Numerical findings indicate that earthquake-induced acceleration is notably amplified by the seabed foundation, particularly in the horizontal direction. The presence of wave loading significantly alters the development of pore pressure, yet it exerts no discernible impact on earthquake-induced acceleration in the seabed. Consequently, the contribution of random waves to seismic-induced seabed response analysis cannot be disregarded.
Effect of Directional Sea Spectrum in Cyclonic Conditions on Responses of a Weathervaning Vessel
Authors: Lubis Michael Binsar , Drobyshevski Yuriy , Kimiaei Mehrdad 
Published: August 2024

Abstract
Accurate representation of wave spectrum is crucial for extreme response analysis of weathervaning vessels under tropical cyclone. It is a common practice to use unidirectional or symmetrical directional wave spectrum for response analysis of floating vessels. However, reported measurements of cyclonic sea states show that directional sea spectrum may be very different from the commonly assumed spectrum. Importantly, the directional wave spectrum of cyclonic sea state is typically skewed, with its higher frequency tail tending to align with predominant local wind, while the peak wave energy at lower frequencies propagates in a different direction, sometime at large angles to wind. Asymmetrical shape of the spectrum may affect responses of a floating structure in different ways. Given that responses in cyclonic conditions usually govern the structural design, there is a need to assess the significance of the directional spectrum for the behavior and extreme responses of a weathervaning vessel.
This paper examines the effect of directional wave spectrum on weathervaning behavior and responses of a generic turret-moored Floating Production Storage and Offloading (FPSO) vessel, exposed to tropical cyclones at the North-West Shelf of Australia. Cyclonic sea states chosen for the study is representative of design metocean conditions generating the 100-year wave load responses. The study compares the directional wave spectra from a hindcast cyclonic database with a commonly assumed spectrum. A parametric formulation for the directional wave spectrum in tropical storms, which was developed in oceanographic research in the last decades, is also considered in the comparison. Results of weathervaning behavior and several wave load responses of the vessel are presented and discussed.
Experimental Investigation of Offshore Wind Turbine Structure on Structural Behavior Under Lateral Loads
Authors: Choi Won Seok , Sohn Jung Min , Kim Sang Jin 
Published: August 2024

Abstract
Expanding renewable energy capacity is becoming increasingly important as the International Energy Agency (IEA) advises reducing carbon dioxide emissions in response to rising energy demand and environmental concerns associated with fossil fuels. Wind turbines, a powerful and efficient means of generating renewable electricity, have seen exponential growth in numbers over the recent decades. Many countries are actively promoting wind turbine construction and research, but despite numerous reports of tower collapses, there has been limited progress in the field of structural reliability studies. Generally, the structural design methods, Allowable Stress Design (ASD) and Load & Resistance Factor Design (LRFD), used for wind turbine towers. To ensure a more robust structural design, it is advisable to consider Ultimate Limit State (ULS), which considers the potential resistance for buckling and post-buckling behavior of the entire structure.
This study presents an experimental investigation of the comprehensive structural response of a structure based on the geometric characteristics and loading conditions of a wind turbine tower. The experiment was conducted on a cantilevered cylindrical shell structure subjected to lateral loading. Both load-displacement curves and strain measurements are presented for a comprehensive understand of structural behavior. The effects of the bottom boundary condition and the initial geometric imperfections of the cylindrical shell on the results are analyzed. It also discusses experiment limitations.
Local Scour Around the Touchdown Zone of a Pipeline-Riser System
Authors: An Hongwei , Hossain Muhammad Shazzad , Kim Youngho , Kim Young-Tae , Bae Kyung-Tae , Golabek Ian , Tabram Jake 
Published: August 2024

Abstract
This paper presents a series of physical model tests for investigating local scour around the touchdown zone of a pipeline-riser system used for liquefied natural gas (LNG) offloading. The local scour around a J-shape pipeline-riser system is influenced by several parameters, including the curvature radius to pipeline-riser diameter ratio (R/D), pipe embedment ratio (e/D), flow intensity (defined by the ratio of the Shields parameter to the critical Shields parameter, θ/θcr), and flow direction (α). The model tests were conducted using a model pipe with a diameter of D = 0.07 m and R/D = 5. Eight different flow directions (α = 0° to 180°) and six pipe embedment ratios (e/D = 0.5, 0.7, 0.9, 1.1, 2 and 3) were examined.
The results indicate that flow direction α affects the equilibrium scour depth significantly for e/D = 3.0. When α ranges between 0° and 122.5°, the curvature of the model pipe appears to intensify the local scouring process. For larger α values, the scour depth is less than that observed around a vertical pile. For e/D = 3.0, local scour is seen to be a constrained process, and the horizontal pipeline remains buried. The equilibrium scour depth diminishes as e/D reduces from 3.0 to 0.7, and no scour propagation is observed along the pipeline on the seabed for this range. For e/D = 0.5, local scour continuously expands in the spanwise direction of the pipeline, leading to the formation of free spans. Critical e/D value for the development of free spans lies between 0.5 and 0.7.
Research on Shock Load Recovery of the Marine Isolator
Authors: Wang Shuang , Guo Jun , Qiu Zhong-Hui , Zhao Xiao-Jun , Zhao Hua-Xun 
Published: August 2024

Abstract
In order to facilitate the development of the impact test and restore the original impact load effect, this paper adopts the combined sine wave method and the composite fundamental wave method to reconstruct the impact load of the marine multi-diaphragm isolator. The advantages and disadvantages of the two methods are analyzed, and the consistency of the response effect of the components under the two shock loads is studied. The results show that the diaphragm isolator demonstrates excellent shock resistance and displacement limitation. The response effect of the isolator under the combined sine wave is different from the original response, and the reduction degree of medium and high frequency load spectrum is poor, which has certain limitations. Compared to the structural response under the original impact load, the acceleration response error under the composite fundamental wave load is 9.37%, and the top vertical deformation error is 12.9%. The composite fundamental wave method effectively recovers the shock load by transforming the characteristic parameters of the base waveform.
Machine Learning Based Prediction of Buckling in Composite Cylindrical Shells Under External Pressure Using Design Code and FEM Analysis
Authors: Lee Hyung Gi , Kim Sang Jin , Sohn Jung Min , Prabowo Aditya Rio 
Published: August 2024

Abstract
Composite materials, known for their strength and weight advantages, find extensive use in the maritime industry. Nevertheless, predicting the buckling pressure of composite cylindrical shells, especially with specific layup patterns, is a challenging task.
This study aims to enhance buckling pressure prediction accuracy through machine learning. The model is trained using data from NASA design codes and finite element analysis in ANSYS. Twenty-four-layer composite cylindrical shells with a thickness of 2.52mm, constructed from carbon-epoxy prepreg tape (USN-125), were subjected to external pressure. Stacking patterns, denoted as [θ/θ]12, , were varied at 2-degree or 5-degree intervals for each method, ranging from 0 to 90 degrees. This variation resulted in a dataset comprising 2378 data points.
A Random Forest machine learning algorithm, which demonstrated higher prediction accuracy compared to other algorithms, was trained on this dataset., with weights assigned to NASA design equations and FEM results at a 1:2 ratio. Predictions using random angle combinations were compared to those solely based on the design equation, demonstrating higher accuracy.
This study represents an initial step in integrating machine learning to enhance buckling pressure prediction accuracy. Future enhancements may involve incorporating post-buckling test data and fine-tuning variable weights in the algorithm to further improve precision.
Real-Time Prediction of Rate of Penetration Using Multi-Gene Genetic Programming
Authors: Ma Baodong , Zhu Zhaopeng , Song Xianzhi , Zhang Chengkai , Liu Zihao 
Published: August 2024

Abstract
The rate of penetration (ROP) is a crucial metric for assessing drilling efficiency. However, the ROP prediction models based on conventional machine learning have high accuracy but poor interpretability, and the offline models make it difficult to capture the dynamic impact of formation and drilling condition changes on ROP. In this paper, a real-time prediction method for ROP using multi-gene genetic programming (MGGP) algorithm is proposed. First, outliers and non-drilling conditions data are eliminated. Through the multicollinearity analysis, seven mud logging variables, weight on bit, rotary speed, torque, inlet flow, inlet density, standpipe pressure, and mud pit volume, are taken as input variables and filtered. Then the explicit expression between variables and ROP is constructed based on the MGGP algorithm, and the variables sensitivity is analyzed. Finally, a real-time update framework is proposed to capture the dynamic trend of ROP, with a coefficient of determination of 0.89 and a mean absolute percentage error of 5.44%. This study verifies the effectiveness of the MGGP algorithm in the prediction of ROP and improves the interpretability of the model, which provides a basis for complex geological drilling process.
A Numerical Analysis of a Hybrid Semisubmersible and Point Absorber Wind-Wave System
Authors: Huang Yi-Chieh , Yu Yi-Hsiang 
Published: August 2024

Abstract
Hybrid wind-wave systems combine a floating offshore wind turbine (FOWT) with a set of wave energy converter (WEC) systems. Although the level of power production is significantly different, integrating a WEC system with the FOWT may be beneficial, such as reducing the FOWT platform motion. This study uses Matlab for Offshore Simulation Tool (MOST) and WEC-Sim to simulate the UMaine VolturnUS-S floating platform with the International Energy Agency Wind 15 MW wind turbine and a wave energy converter (WEC) array with three heaving point absorbers. Both WEC-Sim and MOST are open-source simulation tools. WEC-Sim has been developed and applied to analyze various types of WEC systems. MOST has been developed using WEC-Sim environment and implemented to analyze floating offshore wind turbines. A series of simulations are presented in this paper, including a set of decay tests to verify the MOST+WEC-Sim solutions and selected wind-wave conditions to evaluate the hydrodynamic response of the system. The primary objective is to assess the effectiveness of coupling MOST and WEC-Sim for simulating the hybrid floating wind-wave system across various design scenarios and developing benchmark cases. Finally, the system hydrodynamic response results are analyzed, and the effectiveness of using the WEC system for stabilizing the platform is discussed.
A Shock-Absorbing Non-Hydrostatic Navier-Stokes Solver on σ-GRIDS for Wave Modeling Over Irregular Topography
Authors: Bihs Hans , Ehlers Ronja , Wang Widar 
Published: August 2024

Abstract
In recent times, there has been the introduction of various numerical wave tanks (NWT) based on computational fluid dynamics (CFD) that provide detailed information on wave propagation and associated wave hydrodynamics. Faster solutions for nonlinear wave propagation are desirable for a wide range of ocean and coastal engineering scenarios. High-order spectral (HOS) wave models and fully nonlinear potential flow (FNPF) models are potential options for efficient wave propagation simulations in deep water. In the design of offshore wind substructures, it is often necessary to identify significant wave events, currents, and sediment transport processes together. The dynamics of each phenomenon are interrelated and greatly influence offshore structures. For pure wave propagation problems, a potential flow model is highly effective. However, when simulating wave-current interactions and sediment processes, a viscous flow model that considers turbulence effects is more suitable. This research presents a three-dimensional non-hydrostatic model called REEF3D::NHFLOW, which operates on a moving σ-coordinate grid. By solving the non-hydrostatic Navier-Stokes equations, this model provides detailed results. The grid used in REEF3D::NHFLOW follows the surface and bottom topography, allowing for grid refinement near the water surface or bottom while maintaining low computational effort. Developed within the open-source hydrodynamics framework REEF3D, the new model is fully parallelized and utilizes the domain decomposition strategy and MPI communication between processors. This paper showcases the capabilities of this new and efficient one-phase flow model through the implementation of a free surface and bottom following σ-grid approach.
AL – A Prototype Autonomous Ship Model for Navigating in Ice Conditions
Authors: Bolbot Victor , Sandru Andrei , Saarniniemi Ture , Freter Jan Hendrik , Puolakka Otto , Kujala Pentti , Valdez Banda Osiris A. 
Published: August 2024

Abstract
This paper introduces a scaled-down model of an Unmanned Surface Vessel (USV) named “AL,” designed specifically for navigating ice-covered waters. The development involved utilizing Computer-Aided Design and Computer-Aided Manufacturing (CAD CAM) tools, employing 3D printing in a modular fashion, and assembling the components into an icebreaking hull prototype. Watertightness examinations ensured the vessel’s integrity. AL was then equipped with advanced electronics, sensors, and state-of-the-art positioning algorithms in the ROS 2 environment. Systematic model tests identified critical ship hull parameters, enabling the establishment of basic controllers. These controllers contributed to the development of a basic navigation and control system for AL. The result is a ship model capable of autonomously following a predefined trajectory, guided by waypoints, while maintaining the desired speed in ice channels. The AL model serves as a platform for future research in autonomous navigation within ice-covered environments.
Methodology to Define the Probability of Detection of Failures In Subsea Equipment Considering Multiple Influencing Factors
Authors: Cuba João Pedro B. , Schleder Adriana M. , Martins Marcelo R. , de Barros Leonardo O. , Orlowski Rene Thiago C. 
Published: August 2024

Abstract
Cost optimization of asset management is a central issue in the offshore oil and gas strategy, and risk based approaches has been more and more employed to assist the segment in the concretization of that goal. In this sense, the use of Risk Based Inspection by the petroleum industry has significantly increased. The inspection procedure aims at mitigating the uncertainty related to the asset degradation state, enabling a better quantification of the actual damage, and, consequently, increases the accuracy of remaining life projections. However, information related to the capacity of the inspections methods to detect the failures and the degradation in equipment is scarce in the literature.
The effectiveness of an inspection method is commonly associated with the probability of detection function of the failure modes and the development of PoD curves is highly complex. Thus, in this study, a methodology is proposed to obtain detection probability values for different scenarios associated with inspections carried out in offshore environment. Several factors may influence the detection probabilities, in addition, a factor may have greater influence on one method than on another. Therefore, in this paper, it is proposed a new methodology to define the probabilities of detection, which is an evolution of the method proposed by Cuba et al [1] considering the influence of these factors; the methodology consist of four steps: the definition the probability of detection for standardized scenarios, the definition of the influencing factors impact, the definition of the correlation between the probability of detection for standardized scenarios and the influencing factors and, finally, the update of the probabilities according to the scenario analyzed.
Study on the Performance of Anti-Collision Sandwich Structure for Underwater Vehicles
Authors: Han Enquan , Yuan Siming , Chen Liyuan 
Published: August 2024

Abstract
Underwater unmanned vehicles (UUVs) predominantly operate in deep-sea environments characterized by complex terrains, which increases the risk of collision accidents and consequent significant losses. Enhancing UUV impact protection is therefore crucial. Traditional protective shells for UUVs rely on large-scale plastic deformation of structures to absorb impact energy, but these conventional designs often fall short in meeting impact resistance requirements. This paper introduces an innovative sandwich structure, the annular cylindrical shell chain (ACSC), designed to offer improved anti-impact performance for UUVs. The mechanical response of the ACSC under impact loading is studied, focusing on impact force and stress distribution. By employing an equal-mass design approach, the ACSC cells were arranged at varying angles, with the equal-mass homogeneous cirque serving as a control. This methodology facilitated the identification of the most effective ACSC configuration. Findings reveal that the ACSC configuration with a constant relative density and cells oriented at a 5° angle demonstrates superior impact buffering capabilities. This research contributes valuable insights to the development of new energy-diverting protective structures in the realm of UUV impact protection.
Long-Period Wave Propagation and its Influence on Sediment Transport Over a Typical Beach in West Africa
Authors: Luo Mengyan , Wang Guangsheng , Tong Linlong , Chen Ning , Zhang Jisheng 
Published: August 2024

Abstract
The dominant wave in the west coast of Africa is bimodal spectrum wave consisting largely of long-period swell, where the spectral peak period is large (Tp = 8∼22s). The speed of long-period swell is also great, so the interaction mechanism of long-period wave with seabed is very complicated, which causes strong sediment transport and dramatic beach evolution. Therefore, the water-sediment movement characteristics are very different from those along the coast of China. However, there are few studies on the hydrodynamic processes in West Africa, and the propagation and deformation law of this kind of low frequency swell in the nearshore area and its influence on sediment transport and beach evolution are still unclear, which has caused serious problems to the design and construction of overseas projects, and needs to be studied urgently.
In this paper, according to the characteristics of the west coast of Africa, the typical beach of Benin Bay is selected to establish a physical model test of beach profile, and the shallow water deformation and breaking of waves, the response characteristics of pore water pressure and the changes of nearshore topography are studied. In the experiment, two-peak spectra wave groups and long-period regular wave groups with different incident conditions were set up. Wave height meter, Particle Image Velocimetry (PIV) technology, pore water pressure sensor array and Sony Alpha 3 high-speed camera were used to observe the changes of free liquid surface, boundary layer velocity, pore water pressure gradient and nearshore topography during wave propagation. This study reveals the evolution of wave propagation and sediment transport mechanism under long-period waves in the West African coast, and the results can provide scientific and theoretical basis for beach protection and restoration in Benin sea area.
Numerical Simulation Study on the Ice Load and Ship Motion Response in Formation Navigation in Brash Ice Channels
Authors: Zhang Bihui , Zhao Jiancheng , Wu Chenzhen 
Published: August 2024

Abstract
In recent years, the melting of Arctic ice has intensified due to the continuous increase in the global average temperature, which has made it possible to open Arctic channels. Predicting ice resistance during ice breaking is a crucial issue for navigating polar ships in ice-covered waters. However, studies on the dynamic ice resistance hydrodynamics and ship motion response of subsequent polar ships in channels after ice breaks are rare. This paper employs CFD-DEM technology to investigate the impact of a channel on a polar ship after icebreaking. The contact of discrete particles is simulated with a variant of the spring-damper model. The fifth-order Stokes wave is introduced to simulate wave action based on nonlinear wave theory. The simulation uses overlapping grid technology to model the ship’s motion response under the combined effects of nonlinear waves, currents, and brash ice. The fluid control equation is discretized using the finite volume method, while the volume of fluid method is used to capture the free surface. Finally, the grid independence is verified and compared with that of the direct sailing resistance test of the bare hull. The numerical simulations of the ice impact force, nonlinear wave action, and ship-ship coupling state were found to be in good agreement. The coupling of CFD-DEM methods can enhance the reliability and efficiency of simulating collisions between structures and brash ice. The model developed in this study can be used to investigate the coupling between dual structures and brash ice collisions.