bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Swarming System for Multiple Autonomous Surface Vehicles Using Virtual Matrix and Leader in Ocean Engineering Basin
Authors: Kim Jung-Hyeon , Choi Si-Woong , Son Hui-Hun , Kim Do-Kyun , Kim Dong-Han , Park Jong-Yong 
Published: August 2024

Abstract
This study focused on the development and model testing of the formation maintenance for multiple unmanned surface vehicles (ASVs). Designed as catamarans, these ASVs were equipped with a various of sensor, such as an inertial measurement unit (IMU) and 2-dimensional (2D) light detection and ranging (LiDAR) system. The robot operating system 1 (ROS) was utilized to enhance communication, conveying data such as position, orientation, and situational insights from various sensors. To sustain the formation of these ASVs, a method combining a virtual leader with a virtual matrix was instituted. ASVs were designed to follow each cell numbers, which simplified both the maintenance and modification of their formation. To validate the efficacy of this virtual matrix approach, model tests covering an array of scenarios were carried out at the Ocean Engineering Basin. The indoor Ocean Engineering Basin’s lack of GPS operability led to the integration of an ultrasonic sensor-based Beacon system for precise positioning and enhanced navigational accuracy of the ASVs. Scenarios were designed to enable rotation while preserving row and column formations, considering the basin’s dimensions. Test outcomes demonstrated that the ASVs adeptly maintained their formation, consistently aligning with the cells defined by the virtual leader and matrix.
Numerical Study on Static and Dynamic Load Inversion of Ice Class Propellers
Authors: Qin Xu , Zhou Li , Li Fang , Fu Shixiao , Ding Shifeng , Liu Chao 
Published: August 2024

Abstract
This paper focuses on the inverse analysis of ice loads experienced by propellers during navigation in ice-covered waters. An objective function for inverse load calculation of propellers is established using the least squares method and Tikhonov regularization, based on the characteristics of the propeller structure response equation under both static and dynamic loads. By integrating the structural feature parameters and response of the propeller, the inverse calculation of loads under ice conditions is achieved. The inverse calculated results coincide well with actual loads, which reveals that both inverse methods possess high accuracy and are capable of practical engineering applications. Furthermore, it shows how to arrange response monitoring points on propellers in this paper, which are of significant importance for enhancing the navigational safety of the polar ship.
Extreme Value Analysis of Ship Roll Motion With Consideration of Ice Accumulation
Authors: Chai Wei , Qi Jianzhang , Leira Bernt J. , Sinsabvarodom Chana , Yang Longxia , Ji Shunying 
Published: August 2024

Abstract
Ice accumulation poses a significant threat to ship stability, potentially leading to capsizing if the roll angle surpasses a certain threshold. Investigating the impact of ice accumulation on the extreme roll angle is crucial for the safety and stability of ship sailing in Arctic regions. This article presents a study that aims to evaluate the effects of ice accumulation on ship stability in waves. Specifically, the standard ship model CEHIPAR 2792 is selected, and the dead ship condition is considered. Calculation of the roll damping coefficients via CFD method has been verified with the experimental data. Then, single-degree-of-freedom (SDOF) models for roll motions with and without ice accumulation are established to calculate the roll response in random seas. The influence of ice accumulation on the roll damping term as well as on the restoring term are incorporated into the SDOF model. Finally, extreme value analysis is executed to evaluate the influence of ice accumulation on the roll response and ship stability in waves. This Research has shown that predicting extreme values of roll motion response is a more effective approach in capturing the impact of ice accretion on the stability of vessels in waves, surpassing conventional measures such as restoring lever arm. This methodology enables an enhanced assessment of the hazards associated with icing conditions.
Azimuthing Propulsion in Ice Management
Authors: Hänninen Samuli , Kujala Pentti , Määttänen Pirjo , Heideman Torsten , Korsström Andrei , Viheriälehto Sampo , Koponen Jorma 
Published: August 2024

Abstract
Year-round operations in ice covered areas result in increasing need for specially designed icebreaking vessels. An important characteristic of these vessels is their ice management capabilities. Azimuth thruster propeller wake can be effectively used in ice management (IM) both in stationary Dynamic Positioning (DP) operation and icebreaking. The ice management performance depends on the thrust of the propeller, propeller wake angle and thickness of the ice. Various ice management experiments have been done both in full-scale and model tests to study and demonstrate IM capabilities.
Recent tests were carried out with icebreaker “Polaris”, a Finnish icebreaker with ice class PC4. The novel diesel-electric propulsion system consists of three powerful azimuth propellers, two at the stern and one at the bow. This paper will present results of propeller wake effect on ice management and ice clearing. Ice clearing area depends on the ice thickness, power, heel of the ship and wake angle.
This paper will also discuss the characteristics of azimuth propulsion as well as full-scale test results from the use of Azipod units in ice management operations. These results will show how Azimuth propulsion offers improved ice management performance and greater vessel design flexibility. They will also offer further insight into different possibilities, for example, selection of most suitable azimuth angles for various tasks.
Numerical Study on the Influence of Wettability on the Sphere Surface During Water Entry
Authors: Wu Yanyuan , Guo Chunyu , Han Yang , Li Ruoxin 
Published: August 2024

Abstract
The water entry of objects is a fundamental physics problem and has a wide range of engineering applications, such as ship slamming, spacecraft landing on water, and anti-submarine missiles. Due to large nonlinear deformation, and strong unsteady flow and cavity characteristics caused by large-scale motions at the free surface, it is very difficult to simulate the process of water entry using a numerical approach. In this study, based on the open-source computational fluid dynamics (CFD) code library OpenFOAM, the continuum surface force (CSF) model is introduced into the volume of fluid (VOF) multiphase flow model, and the object motion is realized by overlapping grid technology. A three-dimensional sphere water entry numerical calculation model considering the wettability of the object surface is established. The reliability and accuracy of the numerical method in this paper are verified by comparing with the results of the motion displacement and cavitation morphology evolution of the sphere in the experiment. On this basis, the vertical water entry of hydrophilic and hydrophobic spheres with different initial impact velocities was numerically simulated. The effects of surface wettability and initial impact velocity on cavity evolution and motion characteristics during water entry are analyzed in detail, and the formation mechanism of water entry cavity is revealed.
Analyzing Experimental Data of 6-DOF Motions and Sloshing Impacts In LNG Carriers
Authors: Ahn Yangjun , Choi Mun-Gwan , Park Cheonjin , Kim Sang-Yeob , Park Taehyun , Shim Woohyeon , Ryoo Gyeongbin 
Published: August 2024

Abstract
This research delves into the intricate relationship between the 6-degree-of-freedom (DoF) motion of LNG-related vessels and the sloshing impact loads. Conducted by HD Hyundai Heavy Industries, over a decade of sloshing model tests at Seoul National University’s facility has led to a comprehensive study. The tests involve more than 30 ship models under 5,000 varied maritime conditions. A sophisticated array of over 100 Piezo electric sensors collect data on sloshing impact pressures, alongside the vessels’ 6-DoF irregular motions, across five-hour test periods at real-ship scale. Post-processing utilizes the three-parameter Weibull distribution to extract the three-hour most probable maximum peak pressures as the sloshing loads from the time series data. Subsequently, the study examines the correlation between 18 features of the ship’s 6-DoF motion — encompassing displacement, velocity, and acceleration — and the measured sloshing impact peak pressures. Machine learning techniques are pivotal in determining the significance of each feature, employing both linear and nonlinear analyses including Generalized Additive Models (GAMs). By using elimination methods based on the Light Gradient-Boosting Machine (LightGBM), the research identifies and elucidates the key parameters among the eighteen features that significantly influence sloshing loads. This comprehensive investigation not only deepens understanding of the intricate interplay between ship movements and sloshing impacts but also provides a useful dataset that could potentially inform future navigational strategies and contribute to enhancing safety and efficiency in maritime operations and hull form design.
Numerical Study of Propeller Vibrations and Radiated Noises in the Rudder-Propeller Interaction
Authors: Zhang Weipeng , Wan Qingyuan , Li Xusheng , Hu Jian 
Published: August 2024

Abstract
The inhomogeneous inflow amplifies the loading fluctuations on the propeller which strengthen vibrations. As a significant source of noises, these vibrations of propeller result in more severe noises on the vessels which are detrimental to the health of crews and marine organisms. The study aimed on the vibrations and radiated noises of propeller is beneficial to ideal design of vessels and better comfort. Hence, the vibrations of blades and radiated noises of 5479 propeller operating in inhomogeneous inflow are numerical predicted in present study. The hydrofoils located upstream of propeller are employed to generate inhomogeneous inflow. Firstly, the loading fluctuations on blades are studied with full-rigid propeller. The vibrations on the trailing edge of blade are compared under different rotational speed. The distributions of vibration are also compared under different rotational speed. Then the radiated noises of the propeller are predicted considering the vibrations of the propeller. Results show that the loading fluctuations on the blade are more intense at leading edge. The vibrations on the blades are dominant at shaft frequency (SF), 4SF and 12SF in the inhomogeneous inflow. Several humps of vibrations are observed at the natural frequencies of the blades. The vibrations at 12SF reaches its maximum when the 12SF approaches the first natural frequency. The deformations and vibrations of blades results in weaker tonal noises but more intense broadband noises.
Strength Analysis of Icebreak Ramming Sea Ice With Extreme Thickness Along the Northern Sea Route
Authors: Bian Anqi , Chai Wei , Dong Haibo , Yu Zhaolong , Leira Bernt J. , Xiong Fanghuai 
Published: August 2024

Abstract
In recent years, as a great increment in energy, the Arctic has become a focus for its abundant resources. However, the ice conditions are complex in this area, ships sailing along the Northern Sea Route (NSR) may collide with iceberg, ice sheet, ice ridges, etc. and resulting in structural deformation and damage of the hull. Therefore, the structural safety of the ice capable ships should be mainly considered. In order to estimate the structural safety of icebreakers encountering the sea ice with extreme thickness, numerical modeling calculation has been conducted in the simulation software LS-DYNA. Specifically, four representative sites are selected to predict the extreme thickness of sea ice, based on the statistics of yearly extreme sea ice thickness along the NSR. The ice-breaking conditions and bow stress patterns of icebreakers ramming the sea ice with extreme thickness at different speeds are simulated by numerical methods, and the extreme stresses of the bow ramming area are extracted. On the basis of the results above, the strength of icebreaker bow structure is checked with regulations to provide valid reference for icebreaker design.
Optimisation of the Main Hull Subdivision and Layout Based on Topology-Geometry Co-Characterisation
Authors: Yu Lei , Wang Hao , Luo Junting , Chen Shunhuai 
Published: August 2024

Abstract
The subdivision and layout of a ship’s main hull is a critical aspect of ship design as it directly determines the layout of the ship’s space. To enhance design efficiency and quality, an intelligent optimization method for main hull subdivision is proposed. This method aims to reduce the traditional manual subdivision design process, which heavily relies on mother ship data, and address issues such as long design cycles and high costs. The text describes the sorting and analysis of the mutual influence relationship between ship compartments and equipment. A topological characterization model of the influence relationship and an automatic identification method are proposed. The topological objective function of favourable influences between compartments and equipment is constructed, and the geometrical constraint model is proposed based on the design specifications and design experience. The Diffusion Algorithm Based on P Systems (DAPS) is then employed to achieve the optimization solution, resulting in a collection of intelligent optimization methods for main hull compartmentalization. The test for optimizing the main hull subdivision design was conducted on a scientific research vessel. The iteration curve for the optimization objective showed good convergence, and the optimization had a positive impact on the parent ship subdivision scheme. The test results demonstrate the method’s rationality.
Fatigue Test Geometries Used for Girth Welds and Assessment of Residual Stress: State of the Art
Authors: Englund Even , Chandima Ratnayake R. M. 
Published: August 2024

Abstract
Fatigue testing of girth welds in large tubes plays a crucial role in ensuring the structural integrity and safety of various structures such as oil and gas pipelines, raisers, monopiles, and wind turbines towers. The selection of appropriate test sample geometry and the influence of sample preparation is of utmost importance as it directly influences the accuracy and reliability of the fatigue test results. This review article highlights the significance of fatigue testing of girth welds and the importance of choosing the correct test sample geometry. Another critical aspect highlighted is the assessment of stress concentrations, along with the evaluation of the effects of residual stresses in fatigue testing of girth welds and welds done in close proximity. The choice of sample geometry should be representative of the actual structures being tested and should consider factors such as pipe diameter, wall thickness, weld bead profile, and potential stress concentrations. Improper selection of sample geometry can result in inaccurate fatigue life predictions and limit the practical application of test results. By conducting a literature survey on the geometry for fatigue test specimens of girth welds from large tubes, this study aims to provide insights into the significance of varying sample geometries when testing girth welds and their effects on residual stress and fatigue performance. The survey will include a comprehensive analysis of existing research, guidelines, methods, and standards related to fatigue testing of girth welds. The selection of correct test sample geometry and test method is a key factor in obtaining reliable and accurate fatigue test results. This article highlights the importance and challenges of fatigue testing of girth welds and emphasizes the significance of choosing the appropriate test sample geometry. This is conducted in form of a literature survey to further explore this crucial aspect of girth weld fatigue testing. A framework for future research and testing on girth welds, including welds performed at close proximity, and further assessment of residual stresses is also presented.
Numerical Simulation of the Decay Motion of a Water Column for the Oscillating Water Column Type Wave Energy Converter Using the Particle Method
Authors: Sasahara Yutaro , Morito Makoto , Masuda Mitsuhiro , Tahara Junichiro 
Published: August 2024

Abstract
The floating oscillating water column-type wave energy converter (OWC-WEC) is highly maintainable and safe because it has no moving parts under water. Estimation of water column’s motion in the air chamber is required to develop a high-performance floating OWC-WEC. The traditional approach is to model the system as an equivalent rigid body. The final goal of the present study is to reveal the details of the motion mechanism as fluid by Computational Fluid Dynamics (CFD). In this study, a high-accuracy two-phase flow moving particle simulation method was developed by combining existing and unique models to improve unstable numerical oscillations. Numerical simulations and water tank experiments were conducted for a free-motion test of the water column to validate the proposed method and analyze the fundamental motion of the water column in the air chamber of a floating OWC-WEC. A comparison between the calculated and experimental results showed that the proposed method developed reliably replicated the phenomena, although the three-dimensional effect was important, and the fundamental applicability of the method was clearly demonstrated.
Ocean Wave Spectrum Estimation Using Wave Buoy Analogy
Authors: Son Jaehyeon , Kim Yooil 
Published: August 2024

Abstract
The application of digital twin technology, which combines real-world measurement data with a digital model of the ship, is gaining attention in the field of structural integrity management. Considering the limited number of sensors that can be installed on a ship, the incorporation of a digital twin concept, which combines measurement data with the ship’s digital design model, can play a crucial role in ensuring structural integrity management. This study presents a methodology to estimate local responses at locations where measurements are not available, utilizing both measurement and design data. To estimate the response at unmeasured locations, the directional wave spectrum was first estimated using the least square method, minimizing the error between the estimated response spectrum and the measured response spectrum. In this process, the measured spectrum is obtained by filtering and Fourier transforming the measured time series acquired from the sensor. And the estimated spectrum was obtained through the product of the directional wave spectrum and the Response Amplitude Operator (RAO), followed by integration. And B-spline was introduced to represent the directional wave spectrum. To validate the methodology, artificially generated pseudo-measurement data using wave spectrum and RAO of 13,000 TEU container ship was employed. Subsequently, the directional wave spectrum was estimated using pseudo-measurement data, and the estimated directional wave spectrum, along with the Response Amplitude Operator (RAO), was utilized to estimate the response spectrum.
Experimental Study of the Waves-Induced Flows Inside a Liquefied Silty Seabed
Authors: Chen Ning , Tong Linlong , Huang Zhen , Yang Chen , Zhang Jisheng 
Published: August 2024

Abstract
Silty seabeds are widely distributed around the world and liquefy easily under periodic wave loads, which may significantly affect wave motion and soil dynamics. Laboratory experiments have been conducted to study the wave-induced flows inside the silty seabed, as well as the wave-induced soil dynamic and wave kinematics. Silt particles with a median diameter of 0.06mm are selected to model the seabed, and in the seabed preparation, the Froude-Cauchy similarity criterion is required to satisfy. The free surface elevation, excess pore pressure, and soil motion velocity are measured to study the wave motion and the flow dynamics over and inside the seabed. The experimental results show that: (1) Liquefaction in the silty seabed contributes to a rapid wave damping, manifested as a significant decrease in wave height; (2) Liquefaction occurs when the accumulated pore water pressure in the silty seabed exceeds the vertical initial effective stress. The liquefaction depth develops in a top-down manner; (3) The flow velocity inside the seabed varies periodically. The dimensionless horizontal velocity component of the soil particles in the liquefied seabed is smaller than the vertical velocity component but has a longer period; (4) The instantaneous velocity field of the liquefied soil particles reaches its peak when the water-mud interface moves to the lowest or highest point. When liquefaction just occurs, the instantaneous velocity field is likely to be disturbed by the discharge of bubbles from the unsaturated seabed.
Deep Learning’s Role in Transforming Offshore Asset Corrosion Monitoring
Authors: Bobadilla Roberto Bore , Miranda Barbosa Nicholas , Vera Muñoz Sergio Oscar Alejandro , Lourenço de Souza Marcelo Igor , Caprace Jean-David 
Published: August 2024

Abstract
Maintenance and continuous monitoring of offshore structures and ships are essential in ensuring the integrity and safety of these high-value assets. Manual inspection methods are labor intensive, time-consuming, and often dangerous. Unmanned Aerial Vehicles (UAVs) also called drones equipped with cameras offer a promising solution for efficient data collection. This research addresses the need for automated corrosion detection and classification in images captured by UAVs, revolutionizing asset maintenance practices. Despite advances in computer vision and deep learning, the development of a robust and accurate deep learning algorithm for the automatic detection and classification of corrosion in UAV-captured images remains an underexplored area. Existing methods lack the precision and adaptability required to meet the rigorous demands of offshore asset management. The primary objective of this research is to develop a state-of-the-art deep learning algorithm that can automatically detect and classify corrosion in images of offshore structures and ships, acquired through UAVs. By achieving this goal, we aim to enhance the efficiency and accuracy of corrosion monitoring, thus extending the service life and safety of these critical assets. We employ YOLOv8 (You Only Look Once), a cutting-edge object detection model, as the core of our approach. The model is fine-tuned using transfer learning, leveraging pre-trained weights from a vast dataset to adapt to our specific corrosion detection task. The algorithm is trained on a diverse dataset of corrosion images. Our deep learning algorithm demonstrates good performance in corrosion detection and classification. Through extensive testing on UAV-captured images, it consistently achieves high accuracy, sensitivity, and specificity. The algorithm’s real-time processing capabilities enable swift responses to corrosion-related issues, ensuring timely maintenance interventions. In conclusion, our research presents a novel deep learning approach for automatic corrosion detection and classification in UAV-captured images of offshore structures and ships. The utilization of YOLO V8 with transfer learning significantly improves the accuracy and efficiency of corrosion monitoring. This result contributes to the continuous improvement of asset management practices, offering enhanced safety and extended service life, ultimately minimizing costs and environmental impact in the offshore industry.