bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hydrodynamic Design of a Morphic Autonomous Underwater Vehicle Using Neural Networks
Authors: Becker Quentin , Alam Mohammad-Reza , Immas Alexandre 
Published: November 2019

Abstract
With the advent of Artificial Intelligence and new manufacturing techniques, Autonomous Underwater Vehicles (AUVs) have started to prevail over their manned version in terms of cost efficiency when it comes to accomplish tasks in ocean exploration, offshore platform and ship maintenance or other military missions. As progress has been made over the past years, autonomy remains a topical issue for the untethered AUVs. Drawing its inspiration from nature, this paper aims at minimizing the energy consumed by the device on a specific mission by allowing its shape, parameterized with Bezier curves, to morph throughout time. The framework is restricted to one dimensional trajectories only. A first step consisting of finding the optimal velocity and shapes added mass coefficient in surge as functions of time for a given mission is presented. Then a way of determining the succession of shapes the AUV must take so that it has the right added mass coefficient at any time is proved and used. This last part is made computationally affordable by using a Neural Network instead of a Boundary Element Method to evaluate the hydrodynamic coefficient in surge of the shape. Outliers detection and elimination are being performed on the training dataset to increase the predictive model reliability and robustness.
Investigation of Strain-Based Failure Assessment Based on Reference Strain Method for Welded Pipes
Authors: Lee Jae Sung , Kim Myung Hyun 
Published: November 2019

Abstract
Pipelines are effective means to transport oil and gas. It is essential to maintain the safety of pipelines with the increasing demand for oil and gas resource. Welded pipelines may suffer damage such as cracks during installation and operation, and the consequence evaluation for such damage is very important. Engineering critical assessment (ECA) is the evaluation procedure for structures with flaws and has been widely applied for assessing the pipeline integrity. Although main standards of structural integrity assessment including BS 7910 are stress-based ECA, it is known to produce overly conservative results. In this regard, strain-based ECA has been recently developed.
One of the methods for improving the accuracy of strain-based ECA is the reference strain method. However, only few researches with reference strain method applied to welded pipes are available. Therefore, in this study, a numerical analysis based on the strain-based ECA is performed for strength mismatched girth welded joints with a circumferentially oriented internal surface crack. Equivalent stress-strain curve in BS7910 is employed to reflect the strength mismatch effects in the reference strain. This paper compares the results from the reference strain method and finite element analysis: J-integral and reference strain. Strain capacity of the reference strain method with strength mismatch is also discussed against stress-based ECA.
Experimental and Numerical Analysis of Performance of Oscillating Water Column Wave Energy Converter Applicable to Breakwaters
Authors: Park Sewan , Kim Kyong-Hwan , Nam Bo-Woo , Kim Jeong-Seok , Hong Keyyong 
Published: November 2019

Abstract
In the present study, the primary energy conversion performance of an oscillating water column (OWC) was evaluated through experimental tests and numerical simulations. The experimental tests were performed at an ocean basin located in Korea Research Institute of Ships and Ocean Engineering (KRISO), Korea. A 1/4 scaled OWC chamber model with an orifice to account for the turbine effect was set up at the 3-dimensional basin, and regular wave tests were performed at various incident wave periods. The water surface level inside the chamber, the differential pressure between before and after the orifice, and the airflow speed through the orifice were measured. Computational fluid dynamics (CFD) analysis was performed using the Star-CCM+ commercial software to analyze the performance of the OWC for the same model that was used in the experiment. Detailed flow fields were discussed based on the CFD results, and the numerical and experimental results were compared. The validation results showed good agreement.
Experimental Investigation of Wave Runup on Offshore Intake Wells in a Random Wave Environment
Authors: Prabu Kumar V. , Sundaravadivelu R. , Murali K. 
Published: November 2019

Abstract
The seawater intake system is one of the essential operational units in many industries located in the coastal regions. The selection of the type of intake system to a specific sector depends on the total volume required and the quality of the sea water. The offshore seawater intake wells are a suitable option to meet the large volume water requirement and desired water quality. Sometimes two or more intake wells are installed to supply the large volume of the sea water. Since the increase in spacing between the wells leads to an increase in capital cost, it is predominant important to find the optimum distance between the wells. The present study focuses on the external and internal hydrodynamics of two caisson type offshore intake wells situated in random wave environment. Two wells are fabricated in 1:20 model scale and installed in the shallow wave basin and exposed to the random waves. The outer to outer face distance between two wells changed by concerning the outer diameter (D) of the well such that 1D, 1.5D and 2D. The wave run-up, diffraction wave height and free surface water oscillations inside the wells are measured. The distance between the two intake wells has a significant role in wave run-up and free surface oscillation inside the well. Besides, the H/d have a substantial influence on the wave run-up on the seaward face compared to the side and shoreward face in all three cases. Also, the diffraction wave height is minimum when the wells are separated by 1.5D distance. Moreover, wave run-up and free surface water oscillation are optimum when the separation distance between the wells is 1.5D.
Numerical Simulation of Consecutive Multiple Lateral Impact on the Reinforced Concrete Pier
Authors: Yang Shuai , Xia Xiao-zhou , Zhang Qing , Wang Xue-gang , Ying Zong-quan 
Published: November 2019

Abstract
The consecutive multiple impact resistance of reinforced concrete pier column becomes the most concern in the engineering field. Numerical simulation the process of consecutive multiple lateral impacts is the necessary measures to master the internal mechanism. The fine 3D finite element model is established combining solid element and beam element. The dynamic damage constitutive model of concrete is developed. To react to problem of calculative efficiency and damage accumulation effect, the reduced integration method and full restart analytical method of explicit dynamic analysis strategy is taken using element failure criterion. The translation process of the system energy, the time history value of impact mass acceleration and strain gauge and failure mode of the reinforced concrete pier are compared with the experiment results. The feasibility of the modelling and the validity of the analysis strategy are validated. This study can provide computation basis for research of reinforced concrete structures under consecutive multiple impact.
Time-to-Failure Estimation of Barrier Systems in Permanently Plugged and Abandoned Wells
Authors: Arild Øystein , Lohne Hans Petter , Skadsem Hans Joakim , Ford Eric Patrick , Selvik Jon Tømmerås 
Published: November 2019

Abstract
With the increasing number of aging fields and wells worldwide, a large number of wells will have to permanently plugged and abandoned in the coming decades. Today’s technical solutions on P&A design are primarily driven by legislations or recognized standards such as NORSOK D-10 or the Oil & Gas UK Well Decommissioning Guidelines. The NORSOK D-010 say that the well should be sealing to “eternity” without providing any link between the recommended solution and time-to-failure.
During the last few years, there has been a drive towards a risk-based approach to P&A design. With such an approach, the goodness of a P&A design can be formulated in terms of the associated leakage risk, which consists of two components; i) the time-to-failure of the barrier system and ii) the leakage rate given the barrier system has failed.
When failure data are available, there is a wide range of statistical tools available for establishing the time-to-failure probability distribution. However, barrier failure data on permanently plugged and abandoned wells are scarce in the North Sea region. In order to estimate the time-to-failure for wells in the North Sea region, all relevant information should be taken into account; survival data, expert input and physiochemical degradation models. In this paper, we will show how this can be accomplished by means of a Bayesian reliability approach.
The paper will first describe the general framework for how to perform Bayesian time-to-failure estimation. Thereafter, information pertaining to barrier system lifetime for wells on the Norwegian Continental Shelf (NCS) and relevant assumptions will be discussed. Finally, the methodology will be applied on a synthetic case.
Experimental Research of Wave Transformation on Porous Coral Reef
Authors: Zhu Gancheng , Ren Bing , Wang Yongxue , Wang Chao 
Published: November 2019

Abstract
The influences of reef porosity on wave propagation over coral reef are studied by two-dimensional laboratory experiments. Detailed measurements of wave height and set-up over the reef are carried out under various particle sizes of porous media and incident wave conditions. A comparison of hydrodynamic characteristics between the porous reef and the solid reef is conducted. Based on Gourlay’s [1] model, a dimensionless analysis is conducted to describe the relationship between incident wave conditions and wave set-up over the porous reef.
Local Hard Zones in Sour Service Steels
Authors: Fairchild D. P. , Newbury B. D. , Anderson T. D. , Thirumalai N. S. 
Published: November 2019

Abstract
Hard zones in large diameter pipe have been identified as the cause of the Kashagan pipelines failure, the replacement of which is estimated to cost $3.6B [1–4]. Some hard zone formation mechanisms have been known for years, but one mechanism is “new”, or more precisely, newly recognized. This mechanism can occur during the Thermomechanical Control Processing (TMCP) of plate and specifically during accelerated cooling. The hard microstructure is lath bainite and is isolated in thin (200–500 μm) surface regions. To distinguish the new mechanism from the others these surface regions are given the name local hard zones (LHZs).
There are currently no validated industry standard inspection methods that can be used to detect LHZs. This situation is challenging for an industry that relies on TMCP pipe for sour service applications. This paper explains the LHZ formation mechanism while a companion paper (Newbury, et al [59]) will describe TMCP monitoring techniques that can be used to mitigate the risk of LHZs.
Study on Anchor Leg Installation Sequence of Nanhai Shengli FPSO Under Typhoon Season
Authors: Shen Hui , Wang Huoping , Zhu Weiquan , Wang Deyang 
Published: November 2019

Abstract
Nanhai Shengli (NHSL) FPSO, which is serviced in the South China Sea, was dry-docking to upgrade its internal turret mooring system in the first half of 2018, and the mooring system was re-hooked up to the FPSO subsequently in July. The whole installation of the mooring system will last for more than a month. Based on the metocean data of the South China Sea and operation experience, the mooring system installation may encounter typhoon conditions. The NHSL mooring system consists a 10-legs catenary system. The installation sequence of anchor legs may affect the performance of the mooring system under different intensity typhoon conditions. Steps in the design process of anchor leg installation sequence are described in this paper. Based on the tension and offset derived from the time domain mooring analysis, an optimized installation sequence is obtained in order that the mooring system has a better ability to withstand typhoon conditions.
A 2D Nonlinear Numerical Wave Tank With a Moored Floating Body
Authors: Sun Hui , Helmers Jens B. 
Published: November 2019

Abstract
A 2D nonlinear numerical wave tank is developed to simulate the motion responses of a moored floating body in waves which may experience strongly nonlinear wave-body interactions. The numerical solver is based on a Boundary Element Method which has been developed to solve strongly nonlinear hydrodynamic problems. The method is further developed in this paper to simulate a floating body in waves, where horizontal, vertical and rotational motions can be calculated. An effective algorithm is implemented to separate the added mass forces from the total hydrodynamic forces, thus to make the time domain solution converge more easily. The numerical results for a horizontal circular cylinder in waves are compared with linear theory for small wave steepness for verification and further compared with published model tests and CFD results for high wave steepness as validations.
A Pilot Study on Time-Dependent Dissolution of CO2 in Oil for Prediction of Gas Kick Behaviors in Non-Aqueous Fluids
Authors: Kunju Mahendra , Nielsen James , Chen Yuanhang , Santos Otto L. , Williams Wesley C. , Ribeiro Paulo , Chagas Felipe 
Published: November 2019

Abstract
The influx of gas from formations during drilling or when the well is left undisturbed during tripping, logging, and flow check can dissolve very quickly in Non-aqueous drilling fluids (NAF). The dissolved gas can stay unnoticeable till the gas comes out of solution below bubble point pressure closer to surface. The objective of the paper is to develop a model to predict the time dependent mass transfer of CO2 in oil at subcritical pressures and validate the model using experimental results. Since CO2 is soluble in oil, the interaction between solvent and solute can help us understand the dissolution and mass transfer mechanism of CO2 in oil. A model has been developed by incorporating factors that drive the interaction and the rate of gas loading into the liquid to predict the time-dependent mass transfer. A 1.5 inch vertical low pressure apparatus is used to conduct experiments by injecting CO2 into pressurized static column of oil. Pressure inside the pipe, and mass of CO2 injected are varied to study their effects on mass transfer. Boundary conditions for this model are provided from experimentally obtained data of volumetric mass transfer coefficient of the injected gas and liquid system at gas injection flow rate. The developed time-dependent model has been validated using the data collected from the tests. The volumetric mass transfer coefficient is found to change with pressure. This model can be extended to experiments under high-pressures to replicate the downhole conditions. The model can be modified to include desorption to predict the loading and unloading of gas in NAF, and gas oil ratios at depths along the annulus in a real well.
Application of Nearshore Risk Assessment of Hazard and Vulnerability in Marine Resource Area for National Spatial Planning
Authors: Chien Lien-Kwei , Huang Chi-Wen , Huang Wei-Po , Ku Cheng-Yu , Chang Chih-Hsin 
Published: November 2019

Abstract
Taiwan is surrounded by sea. Thus, with the rapid growth of population, the coastal area can be considered for development in the future to satisfy the needs of the population. Moreover, the marine areas and nearshore areas of Taiwan can be developed and used. Therefore, there is a high concern pertaining to the management and use of marine areas and nearshore areas. The “Coastal Management Law” was announced and implemented in Taiwan on February 4, 2015 and defines the coastal areas in Taiwan. On January 6, 2016, the “National Land Planning Law” was announced, and the national spatial land was divided into four functional zones. This study aimed to designate the marine resource zones. The Ministry of the Interior (Taiwan) announced the national spatial plan on April 30, 2018 and proposed the conditions for the allocation of the marine resource zones. However, the conditions only considered the exclusivity or compatibility of the legal use of the marine areas. Therefore, the results of this study provide details pertaining to the risk level of nearshore areas. In the future, these results could be used as the foundation for the selection of marine resource zones and could be used to propose new plans for the selection conditions of the marine resource zones. The findings of this study can provide the central government agency with a reference for the planning and management of national spatial land.
The Effect of Operational Parameters on Vibration Signals of Wind Turbine Gearboxes
Authors: Koukoura Sofia , Bechhoefer Eric , Carroll James , McDonald Alasdair 
Published: November 2019

Abstract
Vibration signals are widely used in wind turbine drivetrain condition monitoring with the aim of fault detection, optimization of maintenance actions and therefore reduction of operating costs. Signals are most commonly sampled by accelerometers at high frequency for a few seconds. The behavior of these signals varies significantly, even within the same turbine and depends on different parameters. The aim of this paper is to explore the effect of operational and environmental conditions on the vibration signals of wind turbine gearboxes. Parameters such as speed, power and yaw angle are taken into account and the change in vibration signals is examined. The study includes examples from real wind turbines of both normal operation and operation with known gearbox faults. The effects of varying operating conditions are removed using kalman filtering as a state observer. The findings of this paper will aid in understanding wind turbine gearbox vibration signals, making more informed decisions in the presence of faults and improving maintenance decisions.
The Calving Events of Petermann Glacier From 2008 to 2012: Ice Island Drift Characteristics, Assessment of Fracture Events, and Geographical Data Analysis
Authors: Zeinali Torbati Reza , Turnbull Ian D. , Taylor Rocky S. , Mueller Derek 
Published: November 2019

Abstract
The eastern Canadian Arctic is an ice-prone environment that is a vital part of Canadian Arctic shipping lanes. A better understanding of the ice environment and ice characteristics in this region is essential for supporting safe and economical marine activities. This study presents a first analysis of the drift of ice islands that originated from the Petermann Glacier calving events in northwest Greenland between 2008 and 2012. These massive calving events generated numerous smaller ice islands and icebergs through subsequent deterioration and break-up events. Surviving ice features drifted further southward into the Baffin Bay and reached as far as offshore Newfoundland (∼47 °N) for the case of the 2010 calving event. The drift characteristics of Petermann ice islands are evaluated through the analysis of the recently developed Canadian Ice Island Drift, Deterioration and Detection (CI2D3) database. The average drift distance, speed, and directions of the ice islands that resulted from the 2008, 2010, and 2012 calving events were estimated using successive observations of the monitored ice islands in the CI2D3 database. This study also includes an assessment of fracture events, including the total number of ice island break-up events following each massive calving event and the average number of daughter ice islands resulting from each break-up event. A geographical analysis of the data was also performed to present the location of the fracture events, as well as the time series of latitude change of Petermann ice islands from their origin (northwest Greenland ice tongues) to where until they became too small (&lt; 0.25 km2) to be delineated in the CI2D3 database. This information is of particular interest to marine activities in the eastern Canadian Arctic, and oil and gas operations offshore Newfoundland and Labrador.
Scatter in Charpy Data Considered As a Transferrable Parameter
Authors: Mohr William , Birchfield Neal 
Published: November 2019

Abstract
Correlations between Charpy energy transition temperatures and other fracture mechanics parameters have been widely used for many years in steel failure analysis and design. The primary value transferred often has been a transition temperature, such as the 27 J transition temperature. This approach does not consider the scatter in the transition temperature or in the overall Charpy data. This work uses a scatter assessment tool developed by Orynyak et al. and applies it to a wider variety of steels and weldments to see whether it can provide a second parameter to be transferred to fracture assessment. Examples include pipeline steel and structural steel, as well as weldments in both the weld metal and heat-affected zone. While Charpy transition scatter is expected to be high in heat-affected zones, examples can be found in base metals with similarly high scatter.
Experimental Investigation of Absorption and Desorption of Gas in Riser During MPD Well Control
Authors: Kunju Mahendra , Nielsen James L. , Chen Yuanhang , Sun Ting 
Published: November 2019

Abstract
In this experimental work, the absorption and desorption of CO2 (Carbon Dioxide) in oil using a laboratory scale low-pressure experimental apparatus was conducted to study the dissolution behavior of gas in the oil. Estimating the concentration and rate of CO2 transfer from/to a non-aqueous column of static fluid is very important to understand the dissolution of natural gas in an oil-based mud within a well. Studying how natural gas dissolves in an oil-based drilling fluid is of great significance due to risks that a gas kick in an oil-based mud poses to equipment and workers’ health and safety once it is in the riser. By understanding the variables associated with this phenomena, better field practices can be developed and implemented to predict the dynamics of an influx and determine the best course of action when handling the influx.
A laboratory scale experimental apparatus was designed and built to inject CO2 at the bottom of a seven-foot static column of VO. The apparatus has five test chambers that can be closed individually to isolate and measure the concentration of dissolved CO2 in oil in each of the sections. As a part of the experiment, the the backpressure applied to the column of oil was varied to observe how pressure affects the mass transfer due to absorption and desorption within the oil column. The amount of gas injected was 1.0 liter per minute of CO2 with a back pressure of the apparatus ranging from 40 to 80 psi.
The results of this study will influence further experiments and testing using larger scale equipment involving the dissolution of natural gas within various oil-based drilling fluids at higher pressures. This study also allows for the development of an initial time-dependent mass transfer model which will also be used for predicting dissolution dynamics of Methane in diesel for future large-scale testing.