bluuebunny/crossref_metadata_2025_split huggingface dataset:
Real Time Monitoring of Subsea Well Foundation Integrity
Authors: Bolger David , Kilbourn Stuart , Crombie Jeff , Kidd Steven 
Published: December 2020

Abstract
Production wells have been constructed in an area offshore which is known for having localised deposits of very soft soil close to mudline. During well planning, it was identified that two other operators had attempted to drill in the region but had to suspend or abandon the well due to excessive degradation of the soil supporting the well foundation. The objective of this work was to provide real-time wellhead integrity data to support the well management team during operations.
The real-time monitoring system was deployed on a subsea BOP stack and riser during drilling and completion operations to monitor motions. From the recorded signals, wellhead integrity was inferred by determining the BOP stack characteristic frequency and effective fixity depth. These integrity parameters were relayed to the vessel via a hydroacoustic link and then delivered onshore. An automatic alarm system was setup based on pre-defined limits which would be triggered during operations if the integrity of the well foundation became at risk of permanent damage. Additionally, the BOP stack motion data allowed the accumulated fatigue damage to be tracked.
The alarm system provided a regular 15-minute check on the integrity of the wellhead and conductor system. If advisory limits were triggered, the well management team were able to assess weather forecasts and make an informed decision to continue drilling or to disconnect from the wellhead to avoid a period of rough weather. This would prevent excessive degradation of the soil and protect the integrity of the well. When increased BOP motions were observed by the drilling team, operations were able to continue with confidence because the integrity data remained within acceptable limits. This avoided unnecessary downtime, providing significant savings in both cost and rig-time as well as improving the overall safety profile of the operation.
Characterization of Rock and Fluid Properties for Low-Salinity Water Flooding of Highly Paraffinic Oil in a Deep Low-Permeability High-Pressure High-Temperature Offshore Carbonate Reservoir
Authors: Singh N. , Gopani P. H. , Sarma H. K. , Mattey P. S. , Negi D. S. 
Published: December 2020

Abstract
Characterization of the rock and fluids is an essential step in screening a reservoir for Low-Salinity Water Flooding (LSWF). A detailed characterization of rock and fluid properties using appropriate methods is being presented for LSWF in a low-permeability deep carbonate reservoir together with a critical analysis of findings. The techniques used are assessed against other possible alternative methods, with inferences drawn on advantages and disadvantages of each to better interpret and apply data so gathered. In so doing, discussions on their key features as to how they can be used effectively and efficiently to screen a reservoir for LSWF are also provided. Such integration of results with other available reservoir and production data should result in a comprehensive description of the target reservoir, and it will help interpret the mechanisms and process dynamics more reliably during a low-salinity waterflood. This integration should allow us not only to gain confidence on the experimental studies but could also help optimize the key parameters responsible for formulating a more robust, reliable and representative regime for tests relevant to the LSWF prior to its eventual implementation in the field. To authors’ knowledge, such integration of experimental studies has not yet been reported in the literature, particularly for the tight carbonate reservoirs with highly paraffinic oil.
Ship-Wave Impact Generated Sea Spray: Part 1 — Formulating Liquid Water Content and Spray Cloud Duration
Authors: Mintu Shafiul A. , Molyneux David , Colbourne Bruce 
Published: December 2020

Abstract
When a wave impacts a ship, a cloud of water spray may form. This spray water, in cold climates, significantly contributes to the deposition of icing on the ship. Estimation of the spray flux is a first step towards predicting the marine icing. The amount of spray water, termed as liquid water content (LWC), the time of ship exposure to the spray cloud in a spray event known as spray duration, and the frequency at which the spray is generated are all important parameters required to define the spray flux. Most of the spray flux formulas found in the literature are based on field observations of small fishing vessels. Moreover, they consider meteorological and oceanographic parameters only and ignore the characteristic behaviors of the vessel. These formulas are therefore not applicable to any size and type of vessel. This paper develops methods to quantify the spray properties in terms that can be applied to vessels of any size.
Formulas to estimate two crucial spray properties, LWC and spray duration, are derived based on the energy conservation principles and by non-dimensional analysis. The formulas take into account the ship’s principal particulars, its operating conditions, and the environmental parameters. The formulas are validated against full-scale field measurement from a Russian fishing trawler, MFV Narva, and a medium-size US coast guard vessel, USCGC Midgett. Reasonable agreements are found in both cases.
Design and CFD Self-Propulsion Analysis of a Ducted Propeller for a DARPA SUBOFF Hull Autonomous Underwater Vehicle
Authors: Sbragio Ricardo , Moura Alceu Jose dos Santos , Silva Rubens Cavalcante da 
Published: December 2020

Abstract
This paper presents the design and the CFD self-propulsion analysis of a ducted propeller to operate in a DARPA SUBOFF hull Autonomous Underwater Vehicle (AUV). The ducted propeller is of the pump jet type with 9 blades at the rotor and 11 blades at the stator. The interactive process of design and optimization uses the potential lifting line theory and CFD RANS analysis for obtaining the self-propulsion point, with the propeller placed behind the AUV hull. During the lifting line design, the rotor diameter, hub diameter, design rotation, blade section chord and length of the duct are modeled by a Kriging Metamodel technique and optimized through random sampling in order to maximize the quasi propulsive coefficient. The optimized configuration from the lifting line and Kriging Metamodel is analyzed using Ansys Fluent 2019 solver. The CFD analysis behind the hull allows including wake effects, thrust deduction factor and viscous effects directly into the model. The lifting line and CFD processes are used interactively to optimize the pitch, the circulation and the camber until the required thrust is achieved.
The Development of an Analytical Wake Model for the Flow-Field Assessment of Offshore Wind Farms
Authors: Nelson Bryan , Lin Tsung-yueh 
Published: December 2020

Abstract
There are several analytical wake models in current use which have, over the years, been shown to adequately predict the flow-fields through large wind farms. However, many of these wake models are based on momentum theory, which assumes no frictional drag and a non-rotating wake, the effects of which may not be neglected at non-optimum operating conditions. To address these shortcomings, we are developing an analytical wake model, derived from unsteady, 3D, full-rotor CFD simulations of the flow field behind a single wind turbine for its full range of operating conditions. The proposed model will be validated against site data from the literature, as well as against data predicted using commercial tools. This study is part of the development of a framework for the real-time assessment of the wind farm power generation, together with the wind/wave loads acting on the individual wind turbines and their support structures, within a large offshore wind farm.
Hydrodynamic Assessment of a Biofouled Wave Buoy in Coastal Zone
Authors: Islam Hafizul , Campos Ricardo M. , Ferreira Tobias R. S. , Guedes Soares C. 
Published: December 2020

Abstract
Accumulation of biological growth or biofouling can significantly influence the measurement accuracy of a buoy, unless it is cleaned on frequent intervals. This paper addresses the hydrodynamic impact of biofouling on met-ocean buoys moored in coastal zones. The analyses are mostly based on a Brazilian Navy buoy on the coast of Rio de Janeiro – Brazil. After only four months moored in the warm waters of the Guanabara Bay, the same buoy gained 25% in weight due to fouling, with additional important modifications on the shape and drag below the waterline. Initially, historical data measured by the buoy was analyzed to observe changes in its response over time. A motion response factor (lateral motion/vertical motion) was calculated from the data that showed a significant impact of biofouling for particular wave conditions. Next, OpenFOAM is used to perform RANS simulations for the buoy, at three different wave scenarios, in both clean and fouled condition to observe the difference in hydrodynamic response. The results indicated that the response amplitude operator varies notably for low and high-frequency cases between cleaned and fouled buoy. Our paper suggests that standard guidelines related to buoy cleaning intervals for biofouling and uncertainty applied in their measured readings may not be equal for all conditions. Buoys placed near the coast with warmer waters are more prone to biofouling and might have higher uncertainty in their measured data.
Fire Phenomenon of Natural Gas Leak Accidents on the LNG-Fueled Ship Using Computational Fluid Dynamic
Authors: Nubli Haris , Prabowo Aditya Rio , Sohn Jung Min 
Published: December 2020

Abstract
The emission of greenhouse gases has tightened up in the shipping industries, since the International Maritime Organization established the Emission Control Area (ECA), to reduce the emission of NOx and SOx. It results in an increase of Liquefied Natural Gas (LNG) as an alternative fuel for merchant vessels. However, the LNG-fueled ship should be verified with respect to reliability and its safety due to the high risk of natural gas.
This work aims to establish the scenario of gas leak accident, and the critical zone due to fire spreading. The variables of leak size, leak location, wind direction and wind speed were included into the scenario. The probabilistic approach also applied to determine the scenario. This study provides the release duration which is associated to the ignition probability. The Latin Hypercube Sampling was used to generate the credible scenario.
Finally, Computational Fluid Dynamics (CFD) analysis of fire release scenarios was performed by using a commercial package software, Kameleon FireEx. The numerical simulation results show the thermal radiations which consisted of several levels of heat intensity. The size of critical zone can be determined from the contour of thermal radiation.
Unsupervised Trajectory Anomaly Detection for Situation Awareness in Maritime Navigation
Authors: Murray Brian , Perera Lokukaluge P. 
Published: December 2020

Abstract
Situation awareness is essential in conducting effective collision avoidance in potential ship encounter situations. It has been shown that data driven trajectory prediction techniques, utilizing historical AIS data, have the potential to aid in providing such awareness. However, such data driven techniques will not perform well for unusual ship behavior, i.e. anomalous trajectories. Additionally, such anomalies in the dataset can corrupt the predictions. In this study, an unsupervised approach to anomaly detection is presented to aid such trajectory predictions. Gaussian Mixture Models are used to cluster trajectories, such that clusters of both normal and anomalous trajectories are discovered. Further, anomalies are discovered within clusters of normal behavior. Novel trajectories can then also be evaluated based on a parametric description of the historical ship traffic. The approach is shown to be effective in detecting anomalies relevant in such a trajectory prediction scheme.
Evaluation of the Solutions for Calculating Misalignment-Induced Stress Concentration Factor at Girth Welds in Pipelines
Authors: Zhang Yan-Hui , Dore Matthew , Chukkan Jazeel R. 
Published: December 2020

Abstract
Pipelines are commonly joined by girth welds. A centreline offset at a girth weld would inevitably be introduced due to either a difference in wall thickness of the pipes at each side of the weld or due to misalignment. An additional bending stress can result when the pipeline containing the girth weld is subjected to axial loading. This partly contributes to fatigue crack initiation from the weld toe. Therefore, the misalignment-induced stress concentration factor, Km, must be considered in fatigue design of girth welded pipelines.
There are several solutions available to calculate Km including BS 7910, DNVGL-RP-C203 and Connelly and Zettlemoyer. In some cases, the difference in the stress concentration factors calculated using these solutions is significant. This paper reviews these and other solutions and verifies them by finite element results and experimental data obtained through strain gauge measurements. Based on the study, the most appropriate Km solution is recommended.
Time-Domain Simulation of Subsea Equipments Installation Using Hydrodynamic Derivatives
Authors: de Andrade Emerson M. , Sales Joel S. , Fernandes Antonio C. , Ribeiro Mario L. , Teixeira Pedro V. 
Published: December 2020

Abstract
The installation of a subsea equipment such as manifold needs careful planning and coordination. Studies on the behavior of the dynamic responses are crucial to guarantee safety.
Some important factors in these operations include the current profile, waves characteristics, winches motions at topside, and the elastic behavior of the cable (due to resonance effects).
Currently, most of the available commercial codes use simplified models for the hydrodynamic forces of submerged equipment. However, for cases with complex geometries and strong interactions with the environmental loads, those models fail to represent correctly the dynamics.
In this paper we present an initial method and a hydrodynamic model to include terms that allow the modelling of complex behavior of submerged complex geometries by using hydrodynamic derivatives extracted from model tests. To verify the procedure, tests were performed both at a flume tank and at a towing tank. The model was implemented in a commercial code by using a Simplified Buoy model, to which a python procedure that calculated the hydrodynamic forces was attached. The study was divided into two phases: the first one consisted of the verification of the effectiveness of the external routine. This was done for a manifold in 1DOF and then in 6 DOF. In the second phase, the dynamic maneuvering model using Hydrodynamic Derivatives was implemented as an external routine and, using the output from dynamic excitation experiments at small scale with a manifold, kinematical behavior results were compared.
Results showed good adherence, although some further investigations are still needed.
Using Machine Learning to Identify Important Parameters for Flow-Induced Vibration
Authors: Ma Leixin , Resvanis Themistocles L. , Vandiver J. Kim 
Published: December 2020

Abstract
Vortex-induced vibration (VIV) of long flexible cylinders in deep water involves a large number of physical variables, such as Strouhal number, Reynolds number, mass ratio, damping parameter etc. Among all the variables, it is essential to identify the most important parameters for robust VIV response prediction. In this paper, machine learning techniques were applied to iteratively reduce the dimension of VIV related parameters. The crossflow vibration amplitude was chosen as the prediction target. A neural network was used to build nonlinear mappings between a set of up to seventeen input parameters and the predicted crossflow vibration amplitude. The data used in this study came from 38-meter-long bare cylinders of 30 and 80 mm diameters, which were tested in uniform and sheared flows at Marintek in 2011. A baseline prediction using the full set of seventeen parameters gave a prediction error of 12%. The objective was then to determine the minimum number of input parameters that would yield approximately the same level of prediction accuracy as the baseline prediction. Feature selection techniques including both forward greedy feature selection and combinatorial search were implemented in a neural network model with two hidden layers. A prediction error of 13% was achieved using only six of the original seventeen input parameters. The results provide insight as to those parameters which are truly important in the prediction of the VIV of flexible cylinders. It was also shown that the coupling between inline and crossflow vibration has significant influence. It was also confirmed that Reynolds number and the damping parameter, c*, are important for predicting the crossflow response amplitude of long flexible cylinders. While shear parameter was not helpful for response amplitude prediction.
Informing Components Development Innovations for Floating Offshore Wind Through Applied FMEA Framework
Authors: Rinaldi Giovanni , Thies Philipp , Johanning Lars , McEvoy Paul , Georgallis Georgios , Moraiti Anastasia , Cortés Lahuerta Carlos , Vidmar Marijan 
Published: December 2020

Abstract
Future offshore wind technology solutions will be floating to facilitate deep water locations. The EUH2020 funded project FLOTANT (Innovative, low cost, low weight and safe floating wind technology optimized for deep water wind sites) aims to address the arising technical and economic challenges linked to this progress. In particular, innovative solutions in terms of mooring lines, power cable and floating platform, specifically designed for floating offshore wind devices, will be developed and tested, and the benefits provided by these components assessed. In this paper a purpose-built Failure Modes and Effect Analysis (FMEA) technique is presented, and applied to the novel floating offshore wind components. The aim is to determine the technology qualification, identify the key failure modes and assess the criticality of these components and their relative contributions to the reliability, availability and maintainability of the device. This will allow for the identification of suitable mitigation measures in the development lifecycle, as well as an assessment of potential cost savings and impacts of the specific innovations. The methodology takes into account inputs from the components developers and other project partners, as well as information extracted from existing literature and databases. Findings in terms of components innovations, their main criticalities and related mitigation measures, and impacts on preventive and corrective maintenance, will be presented in order to inform current and future developments for floating offshore wind devices.
Numerical Simulation of Hydrodynamics Around Net Meshes Using REEF3D
Authors: Wang Gang , Martin Tobias , Huang Liuyi , Bihs Hans 
Published: December 2020

Abstract
Hydrodynamics and turbulence around net meshes have drawn more and more attention because it is closely related to forces on the structures and safety issues of offshore fish farms. In terms of numerical modeling of forces on nets, Morison or screen force model is ordinarily adopted to account for its hydrodynamics. However, these methodologies mainly rely on empirical experimental or cylindrical hydrodynamic coefficients, neglecting flow interactions between adjacent cruciforms or net bars. In this study, REEF3D open-source hydrodynamic toolbox is adopted to analyze flow around net meshes explicitly and investigate the hydrodynamics related to forces on the structure. The simulation accuracy is in good agreement with flume experiments and previous research. Flow velocity and vorticity around net bars and knots are investigated. The results demonstrate that 2 × 2 or 3 × 3 mesh cases are more reliable when studying turbulence around net meshes, flow interactions around adjacent net bars, knots should be taken into consideration. Two patterns to control Sn, one is to change the diameter of net bars and the other is to control length, have different effects on the flow around meshes. This paper presents a first step in the aim to derive a new empirical formula for Cd depending on Sn, and Re, which are more related to the physics in offshore conditions.
Vibration Control of a Jacket Offshore Wind Turbine Under Earthquake Wind and Wave Loads by Tuned Mass Damper
Authors: Li Xin , Wang Wenhua , Pan Zuxing , Wang Bin 
Published: December 2020

Abstract
The fully coupled analysis model of a jacket offshore wind turbine (OWT) is established based on the governing equation of motion of the structure which is derived in accordance with the blade element momentum theory (BEM), Morison formula and theories of structural dynamics. The dynamic characteristics and structural responses of the jacket OWT under the different combined seismic cases are analyzed. It can be seen that the interactions of the wind and wave loads are non-negligible in the seismic analysis of an OWT, and the abundant dominant frequencies of the responses of the support system under the combined seismic cases are discovered. Meanwhile, the passive control method of tuned mass dampers (TMD) is applied to the support system of the OWT under the earthquakes, and the influence of the TMD parameters on the reduction of the responses of the support system are investigated. Furthermore, according to the reduction of the structural responses, the suggestions for the design of a TMD under the combined seismic cases for the bottom fixed OWT are summarized.
Experimental Investigation on Vortex-Induced Vibration of Dual Pipes With Unequal Diameters in Tandem
Authors: Zhang Mengmeng , Fu Shixiao , Zhang Zhiqi , Ren Haojie , Xu Yuwang 
Published: December 2020

Abstract
With the massive use of buddle risers and pipelines in deep-water oil production industries, the demand to focus on the research of interference effects of dual pipe has been greatly enhanced. This paper presents interference experiments of dual flexible pipes with unequal diameters under uniform flow with Reynolds numbers ranging from 1.8E3 to 1.1E4. The pipe with larger diameter was set to be the upstream pipe. Various tandem arrangements with wall surface-to-wall surface distances being 3D to 8D were tested, where D is the smaller pipe diameter. Fiber Bragg grating (FBG) strain sensors were used to measure both in-plane and out-of-plane strain responses. Modal superposition method was applied to reconstruct IL mean displacement. Significant interference effect was found under the condition that wall-to-wall gap is smaller than 8D, where CF and IL vibration frequency ratio of downstream pipe equals to 1.0 and IL mean displacement gets smaller compared to those of single pipe in isolation. Moreover, a special ‘capture’ phenomenon, that the dominant vibration frequency and mode of downstream pipe were as the same as that of the upstream pipe subjecting to the uniform flows, was found when wall-to-wall distances were 4D and 8D.