bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Feasibility of Large-Scale Resonant Fatigue Testing to Study Bolt Force Relaxation
Authors: Van Wittenberghe Jeroen , Vanden Haute Cedric , Shirzadeh Rasoul , Thibaux Philippe 
Published: October 2022

Abstract
Offshore wind towers are generally connected with the foundations by a bolted joint. Bolt preload relaxation and loosening result in regular inspections and maintenance. This project describes results of both static and dynamic bolt relaxation tests on a large-scale bolted flanged joint. The tests are carried out on a resonant bending fatigue test setup. These tests serve as a feasibility study to demonstrate this testing method is suitable for efficiently studying the bolt behaviour. The bolts are preloaded up to 90% of their yield stress. Static relaxation between 5 and 28% of yield stress was measured over a period of 20 days. The dynamic testing is spread over 6 days with a total of 1.5 million cycles resulting in a maximum relaxation of 7% of yield. The dynamic test program consists of loading blocks with different amplitudes and intermittent pause periods. Additionally, the Schmidt-Neuper relation between tube shell stress and bolt force is experimentally investigated during the dynamic tests. Initially, the measured bolt forces are lower than predictions by the Schmidt-Neuper relation. However, bolt forces increased significantly after an overload test.
Theoretical and Experimental Analysis on Low-Cycle Fatigue Crack Initiation for High Strength Steel Stiffened Plates
Authors: Lei Jiankang , Yue Jingxia , Xu Zhiting , Fang Xuan , Liu Hongrui 
Published: October 2022

Abstract
The ship hull is generally subjected to asymmetric cyclic loads under various and complex oceanic environments. Especially, under extreme sea conditions, the loads suffered by ship structures conform to the characters of low-cycle fatigue loads. Consequently, the large-scale plastic yield may occur at the locations of stress concentration part of the ship structure due to structural discontinuity or initial defects and result in low-cycle fatigue damage. However, the commonly used methods for low-cycle fatigue life prediction do not premeditate the influence of large range of yield and asymmetric load. Therefore, the effect of mean stress on the crack initiation life of the stiffened plate, the basic unit of ship structure, is investigated in this paper. The crack initiation experiments of welded stiffened plates under different stress amplitudes and stress ratios were carried out. Moreover, the modified Neuber rule considering the large-scale plastic yield and several strain-life models considering the influence of mean stress were used to estimate the life under experimental loading conditions respectively. Different life results were predicted by various strain-life models and compared with the results of experiments. The comparison shows that the modified Neuber rule can accurately describe the local stress-strain at the root of notch in the state of large-scale plastic yield than the Neuber rule, and the Walker model is the most recommended to predict the low cycle fatigue crack initiation life.
Hydrodynamic Coefficients of Generic Subsea Modules in Forced Oscillation Tests – Importance of Structure Parts
Authors: Abrahamsen-Prsic Mia , Solaas Frøydis , Kristiansen Trygve 
Published: October 2022

Abstract
A systematic study of the hydrodynamic coefficients for simplified subsea modules has been performed, to support the estimation of the coefficients needed for planning of subsea installation operations. The coefficients are assessed for a nearly two-dimensional test setup. The tests are performed as forced oscillations at various amplitudes and periods, representing the forces on the module lowered through the water column.
The importance of each of the main components of the subsea modules — mudmat, protection roof and process equipment of different shapes inside the modules are studied at fully submerged condition. Results for the module elements, generic contents and different combinations of these elements are presented.
For the tested modules, damping is generally the dominating hydrodynamic force. However, the presence of the content inside the modules will generally increase the importance of added mass.
Estimation of the hydrodynamic coefficients by summation of the coefficients for the individual structure elements generally overestimates the damping, compared to the coefficients measured for the complete modules. For added mass, estimation based on summation gives generally good results.
Artificial Underwater Dataset: Generating Custom Images Using Deep Learning Models
Authors: Polymenis Ioannis , Haroutunian Maryam , Norman Rose , Trodden David 
Published: October 2022

Abstract
The rapid developments in underwater operations by the offshore industry and the scientific community have led to more sophisticated Underwater Vehicles. Notably, many underwater operations such as inspection of underwater structures are done with the help of Autonomous Underwater Vehicles (AUVs). In recent years autonomous vehicles have benefited immensely from the advancements in the area of Artificial Intelligence (AI) and particularly in Deep Learning (DL). Although DL models and applications are extensively used in different areas, such as in Aerial Unmanned Vehicles, Autonomous Car Navigation, and other applications, they are not so widespread in underwater applications mainly because of the difficulties in obtaining underwater datasets for a given application. In this regard, the present work takes the recent advances that have been made in the DL field and creates a custom dataset by using images of objects taken in a controlled, lab environment. Generative Adversarial Networks (GANs) were used to generate underwater images by combining the images taken in a lab and images with underwater environment characteristics. The results showed that it is possible to create such a dataset since the generated images were close to the actual underwater conditions. Consequently, artificial datasets of the underwater environment can overcome the difficulties arising from the limited access to real underwater images and be employed in projects with specific needs in autonomous underwater operations.
Underwater Vehicle Manipulator System (UVMS) With BlueROV2 and SeaArm-2 Manipulator
Authors: Skaldebø Martin , Schjølberg Ingrid , Haugaløkken Bent O. A. 
Published: October 2022

Abstract
This work presents a novel digital twin for an underwater vehicle manipulator system (UVMS). The twin represents a framework for low cost UVMS and builds on the BlueROV2 and the SeaArm-2 manipulator. UVMS’s are currently applied in ocean interventions and the presented platform enables testing and verification of intervention methods in subsea inspection, maintenance and repair operations. The UVMS twin represents an excellent research platform for such systems as it is low cost with highly accessible and customizable software. The paper further presents a platform for the UVMS where the robotic system is modeled in the Gazebo simulator. The Marine Cybernetics laboratory at NTNU is modeled and the UVMS can be deployed into this environment for testing before deployed in real world experiments. The twin represents a simulator which offers a base where overall system, control system, communication, etc. can be tested before progressing to real world experiments. The low cost of the equipment is essential to perform experiments and tests of subsea intervention efficiently and at a sustainable cost.
Assessment of Power Requirements for Alternative Vertical Transportation System for Deepsea Mining
Authors: Sevillano Lucas Cantinelli , Sangesland Sigbjørn 
Published: October 2022

Abstract
The continuous expansion of the technology sector is dependent on metals currently found at very low concentrations on land-based mining operations. Therefore, mineral deposits located on the seafloor are considered future valuable resources, given the high concentration of sought-after metals.
Considerable research has been made in concepts and technologies to ensure the safety and viability of seafloor mining. Because the mining operation could take place under water depths of up to 6000 m, transporting the ore to the surface is a critical part of the operation, for which different concepts have been proposed. An often-observed concept in publications is to use a free hanging riser with pumps installed along it as the conduit to the slurry. However, other concepts may be feasible.
In fact, seafloor mining may benefit from copying the practices of the offshore oil and gas industry. Drilling offshore wells employs a drill string and a riser. Drilling fluid is pumped into the well through the drill string, and it returns to the surface through the annular space between drill string and riser. Among other purposes, this fluid removes the rock cuttings from the bottom of the well and transports them to the drilling rig.
This paper proposes that a system which employs much of the equipment already available in conventional offshore drilling rigs is used for transporting the production of seafloor mining. This system is compared to other transport concepts typically proposed for seafloor mining. The analyses presented in this paper focus on power requirements for delivering the design ore production. The calculations conducted take into consideration the extensive published research on vertical transport of slurries. The annular vertical transport of slurries, as proposed in this paper, presents several advantages with consideration to required power, flow circulation, mineral production rates, handling of plugs, and maintenance of equipment. These results justify future further analyses of the proposed transport system.
Potential and Consequences of Earthquake Induced Liquefaction Under a Gravity Based Structure
Authors: Carlton Brian , Lee Patrick , Belloni Filippo , Kaynia Amir M 
Published: October 2022

Abstract
This study focused on the potential liquefaction due to earthquake shaking of a gravity based structure (GBS) located off the northeast coast of Italy in the Adriatic Sea. The reinforced concrete GBS is 88 m wide by 180 m long and is underlain by a sand unit with variable thickness that could cause differential settlement and sliding. We first estimated settlements using cone penetration test (CPT) based liquefaction triggering methods and simplified settlement calculations with adjustments to account for the influence of the GBS. We then performed the same calculations but with the earthquake demand estimated from 1D site response analyses. Finally, we performed 2D finite element analyses of the soil-structure system using the advanced constitutive model PM4Sand to model the liquefiable sand layers. The results show that the total amount of displacement is small (1.5–7.5 cm), and no significant differential settlement or sliding is expected for the design earthquake scenarios. A practical observation from the study is that the more detailed and integrated analyses resulted in lower estimates of settlements and a more accurate representation of the soil-structure response.
Kinetic Characteristics and Hydrodynamic Forces on Semi-Planing Typed High-Speed Vehicle by Model Test and RANS Simulation
Authors: Hasegawa Kenta , Araki Motoki , Ishida Kei , Yukawa Kazuhiro , Saito Shota , Sano Ryoya , Uemura Keisuke 
Published: October 2022

Abstract
This paper aims to understand the kinetic characteristics and the hydrodynamic forces on a semi-planing typed high-speed vehicle during moving straight in calm water and in head waves. One of the features of this vehicle is considerable variation in its attitude due to the changes in the resistance value and propulsion performance associated with the change in a Froude number of the vehicle, and no reliable method has been established to evaluate this feature in advance. Therefore, we conducted free/captive towing tests at Froude numbers ranging from 0.03 to 1.8 using a scale model of the vehicle. The results show that the vehicle can move straight stably without unstable vibration even at high Froude numbers. In addition, we performed 3D unsteady RANS (Reynolds-Averaged Navier-Stokes equation) simulations for the vehicle with Froude numbers of 0.9, 1.2, and 1.8 in calm water and found that the RANS simulation could reproduce the experimental results relatively well with respect to the vehicle’s attitude, the drag coefficient, and the free surface shape around the vehicle.
A Special Thread Design Based on TC4 Titanium Alloy and its Successful Application in Offshore Extended-Reach Drilling
Authors: Li Zhenkun , Yin Qishuai , Guo Yingying , Long Yang , Li Minshi , Zhou Xu , Guo Shujun , Meng Fanhua 
Published: October 2022

Abstract
Short radius drilling (dogleg &gt; 20°/30m) increases yearly to satisfy the growing demand for infill and sidetrack wells during offshore oil development due to the limited operating space. TC4 titanium alloy threads perform better than steel and iron-based or nickel-based alloy threads for short radius wells. However, the current thread design of commonly used tubing and casing strings is not appliable to TC4 titanium alloy threads.
This paper first designed reasonable ranges for radial interference (pitch diameter) and sealing surface interference of the TC4 titanium alloy thread. Then, the reasonable range of pitch diameter radial interference and sealing surface interference were validated by finite-element analysis and verified by make-up and breakout tests under different working conditions. In the end, tubing and casing strings with appropriate thread were made and tested by a third party. Testing results supported our thread design. Furthermore, the TC4 titanium alloy tubing and casing strings with the designed thread in this paper have been successfully applied in more than 100 offshore extended reach wells with a maximum deviation of 90°. Hence, our thread design is acceptable and recommended widely used in offshore extended reach drilling.
Leading-Edge Tubercles Applied Onto a Flapped Rudder
Authors: Troll Moritz , Shi Weichao , Stark Callum 
Published: October 2022

Abstract
The addition of a trailing edge flap is an effective way to enhance the lift generated by marine rudders. This is achieved through camber being introduced into the foil section when the flap is deflected. But the strong curvature in the flow around the flap’s leading edge makes it prone to early flow separation and increased drag. Leading-edge tubercles offer a means to control flow separation whilst improving lifting performance at post-stall angles of attack (AOA). Therefore, this study aims to investigate the tubercle leading edge’s (TLE) ability to improve the hydrodynamic performance of a flapped rudder. A finite-span reference rudder with a 20% trailing-edge flap and its TLE modification were numerically analysed using Detached Eddy Simulations (DES) for fully turbulent flow at a Reynolds number of 1.15 × 106.
Flow separation severity and progression were controlled and minimised through the TLE modifications. As a result, the TLE rudder produced up to 15% higher maximum lift and up to 25% more post-stall lift. The rudder efficiency also improved for various rudder and flap angle combinations.
The Role of Surface Roughness on Pitting Corrosion Initiation in Nickel Aluminium Bronzes in Air
Authors: Dobson Tamsin , Larrosa Nicolas , Kabra Saurabh , Coules Harry 
Published: October 2022

Abstract
Nickel Aluminium Bronze (NAB) continues to be used extensively in the marine industry and is most commonly seen in valves and propellers due to its strength and corrosion resistance. However, components used for marine applications often endure long exposure to air during storage periods prior to installation and NAB is vulnerable to pitting corrosion in air. To investigate the potential condition of stored NAB, this study measured the height, width and percentage coverage of corrosion pits observed in NAB samples after 4 months of air exposure at room temperature in a laboratory.
Four different types of NAB samples were considered; off-the-shelf (sample 1a), polished (sample 1b), laser beam welded (sample 1c) and failed in service (samples 2a and 2b) and the microstructure of the samples was characterised using a mixture of microscopic techniques including surface roughness characterisation, SEM, EBSD, EDX and neutron diffraction.
Examples of pitting corrosion were found on each sample type after 4 months of exposure to air. The results show significant correlation between surface roughness of the pre-corroded sample and pitting coverage, and this is thought to be due to the development of crevice corrosion during the 4 months of air exposure. It also highlights the inaccuracies in using Ra values alone to measure surface roughness in samples where localised corrosion pits are suspected due to high surface roughness or long periods of air exposure.
The results of this study bring into question the pitting corrosion that would be found in components that are stored for longer period before being installed onto vessels. This has concerning safety implications as the initial surface characteristics of the metal may influence the residual load-bearing capacity of components.
Dynamic Analysis of Collision Between Two Floating Bodies Considering Hydrodynamic Loads
Authors: Cerik Burak Can , Choung Joonmo 
Published: October 2022

Abstract
This paper presents a simulation model for coupled simulation of external and internal mechanics of two colliding floating bodies. The model employs a rigid body motion solver, which calculates the hydrostatic restoring, wave radiation forces and solves the 6-DOF motion components in time domain. Rigid body solver is coupled with the structural analysis code Abaqus/Explicit using a user-defined load subroutine. The load subroutine is verified by comparing the benchmark analysis results for heave motion of a sphere. A case study is presented considering a simple box-shaped ship hit by a floating object with a wedge-shaped bow. Simulations are run by considering hydrodynamic loads on the struck ship. The importance of roll restoring and added mass effects are highlighted.
Identification of Wave Drift Forces on a Floating Wind Turbine Sub-Structure With Heave Plates and Comparison With Predictions
Authors: Fonseca Nuno , Nybø Synne , Rodrigues José Miguel , Gallego Aitor , Garrido Carlos 
Published: October 2022

Abstract
The paper presents empirical quadratic transfer functions (QTFs) of the horizontal wave drift loads on a turret moored floating wind turbine in operational and in severe sea states. Comparison between the empirical results and potential flow predictions of mean wave drift coefficients provide an assessment of the limitations of state of the art numerical tools.
The floating substructure has a catamaran configuration with heave plates to minimize the vertical motions. The empirical QTFs are determined from cross bi-spectral analysis of model test data obtained in an ocean basin. Validation of the identified QTFs is provided by comparing low frequency motions reconstructed from the empirical QTF with measurements. The comparisons are performed in terms of low frequency spectra and motion time histories.
The numerical mean wave drift coefficients are calculated by a panel code that solves the wave-structure linear potential flow problem. Systematic comparisons between numerical predictions and empirical QTFs allows identification of tendencies of the empirical QTFs and limitations of the potential flow predictions, namely with respect to the sea state severity and with respect to wave-current interaction effects. The results indicate a decrease of the wave drift coefficients with increasing sea state severity. Furthermore, wave-current effects for collinear conditions increase the empirical wave drift coefficients.
A Kalman Filtering Technique for Prediction of Wave Time Histories Around Ship Based on Response Measurements and its Experimental Validation
Authors: Komoriyama Yusuke , Iijima Kazuhiro , Fujikubo Masahiko 
Published: October 2022

Abstract
In this paper, a Kalman filter technique for identifying the wave time histories encountered by a ship is developed and verified in a series of tank tests. The method inversely analyzes the wave time histories from the measured response. A series of irregular wave tests using a flexible ship model made of acrylic resin was conducted at the Actual Sea Model Basin of National Maritime Research Institute, Japan. Then the wave elevation, the rigid body motions such as heave and pitch, and the vertical bending moment (VBM) at several sections were measured in the test. Optical fiber Bragg grating (FBG) sensors were equipped on the model to find the VBM distribution. The estimation accuracy for the wave time histories is discussed by comparing the estimation with the measurement. The same technique is found to be effective in predicting the wave time histories in a few cycles ahead.
Electroencephalographic and Autonomic Correlates of Imaginary and Real Movements of Legs in Right-Handers and Left-Handers
Authors: Vedyasova O. A. , Morenova K. A. , Pavlenko S. I. 
Published: October 2022

Abstract—
Changes in the spectral power (SP) of electroencephalogram (EEG) in the α-band and the heart rate variability (HRV) were studied in subjects with right and left motor dominance profiles during imaginary and real flexion of right and left feet. During the implementation of motor tasks, a pronounced desynchronization of α-rhythm in frontal and central leads and its less significant changes in parietal and occipital zones of both hemispheres were revealed. The peculiarity of right-handers during mental and real leg movements was the variable and asymmetric character of changes in the SP of α-rhythm in the bilateral leads from various cortical areas. In left-handed subjects, when imagining and performing movements, the desynchronization of α-rhythm in different leads had the same severity and there were practically no hemispheric asymmetry in SP. Right-handers had are latively stable vegetative status during the performance of motor tasks, and HRV changes occurred mainly with real leg movements. In left-handers HRV parameters changed more strongly and mainly during mental actions with their feet. Correlations were found between the α-rhythm SP and HRV parameters, depending on the type of movement and the motor dominance profile of subjects. The obtained data reflect the peculiarities of regulation mechanisms of voluntary leg movements and the differences in the vegetative support of motor activity in right-handed and left-handed people.
Immediate sequential bilateral cataract surgery: a 13-year real-life report of 56 700 cataract operations
Authors: Hujanen Pekko , Vaajanen Anu , Felin Tuukka , Lehtonen Eemil , Syvänen Ulla , Huhtala Heini , Helminen Mika , Sintonen Harri , Tuulonen Anja , Uusitalo-Järvinen Hannele 
Published: October 2022

Background/aims
To assess the frequency of immediate sequential bilateral cataract surgery (ISBCS) and endophthalmitis during 13-year period in Tays Eye Centre, Tampere University Hospital, Tampere, Finland.

Methods
All cataract surgeries performed between 1 January 2008 and 31 December 2020, and all endophthalmitis cases during the same period were searched from electronic patient records. Numbers and frequencies of ISBCS, and complications, including endophthalmitis and vitreous loss, were recorded and compared with unilateral operations.

Results
The study included 56 700 cataract surgeries in 34 797 patients of whom 39% (n=13 445) had ISBCS. The median age of the patients was 75 (IQR 68–80, range 0.08–99) years at the time of surgery. The proportion of ISBCS patients increased from 4.2% in 2008 to 46% in 2020. Vitreous loss occurred in 480 (0.9%) of cataract surgeries. There were no postoperative endophthalmitis after cataract surgery (n=0) during the 13-year period.

Conclusion
The proportion of patients undergoing ISBCS increased from 4.2% in 2008 to 46% in 2020. No endophthalmitis were found to be associated with ISBCS.