bluuebunny/crossref_metadata_2025_split huggingface dataset:
Behaviour of a Suspended Wellbay Module and Flare Tower in Waves During Transit to Shore
Authors: Chan Hoi-Sang , Armaoğlu Evren , Thomson Matthew , Garner Alistair 
Published: November 2019

Abstract
The extended lift operation to deliver the Wellbay module (M5) combined with the Flare Tower (M8) from the Miller Platform in the North Sea to the shore using the Semi-Submersible Crane Vessel S7000 was restricted by the clearances between M5/M8 and the vessel crane booms. A method to calculate the clearances of the M5/M8 normal to the vessel crane booms has been developed and used in a frequency-domain response analysis to define operability limits. Investigations based on a series of scale model tests in regular waves and irregular short-crested waves including motion decay tests in calm water, conducted by the Maritime Research Institute (MARIN) in the Netherlands, were also made to further evaluate the behaviour of the suspended M5/M8 on S7000’s main hooks during transit. The time series of decay motions of the suspended M5/M8 obtained from the decay motion tests and a time domain analysis are compared and used to derive rigging damping. The numerical results of the frequency-domain analysis are validated with the experimental data for response amplitude operators (RAOs) found in regular waves and pink noise waves, significant and 3 hour most probable maximum/minimum (MPM) responses of interest in irregular waves.
Thorough Verification and Validation of CFD Prediction of FPSO Wind Load for Confident Applications
Authors: Xu Wei , Huang Zhenjia (Jerry) , Kim Hyunjoe 
Published: November 2019

Abstract
This paper presents our verification work on CFD modeling practice for the prediction of FPSO wind loads. The modeling practice was developed from the TESK CFD JDP [1]. In the verification, the measured data from a benchmark model test were used to check CFD simulation results. The exact physical model of the model test was used in the numerical modeling (model-of-the-model). To establish high confidence in the CFD modeling and simulations, the modeling practice was thoroughly verified, which covered the following critical elements: mesh resolution, domain size, outlet boundary condition, turbulence model, Reynolds effect, wind profile, prism layer effect on total wind forces, effects of the gap between wind tunnel floor and model bottom, blockage effect due to tunnel side walls and ceiling, and effects of geometry details (small size pipes). The verification results show that CFD can be used as an alternative tool for predicting wind loads and moments on a FPSO for engineering purposes following the modeling practice, and careful QA and QC.
Section Translational Movement Imposition for Macroelements
Authors: Provasi Rodrigo , de Arruda Martins Clóvis 
Published: November 2019

Abstract
Boundary conditions play a very important role in any mathematical model. They heavily influence the response near the region they are, but the farther the interest region is, the less important the boundary condition influence becomes. Also, the response depends of which movements are constrained or imposed and which are not. This influence can be seen in all type of problems, ranging from simple beams to complicated structures.
For tubular structures, such as flexible pipes and umbilical cables, the boundary conditions are usually given in terms of imposed movements in sections, which are commonly assumed, by hypothesis, as rigid bodies. To deal with this type of structures, the authors presented in previous works the macroelements. They are finite elements that incorporate geometrical characteristics in the formulation, leading to well behaved contact models with a smaller number of degrees of freedom.
One major feature of the model is the orthotropic cylindrical layer that uses Fourier series for the displacements. This led to specific contact models and bring the difficulty in the representation of boundary conditions in terminal sections, since different nature displacements (one the aforementioned Fourier and other one standard description) must be dealt with.
This paper address how to impose translational movement for sections using macroelements. All the description of how the coupling is made and the constraint enforcement done by using a penalty-based formulation. This work also highlights the implementation, finalizing with comparison with a conventional finite element program.
Application for Improved Awareness of Cable Geometry During Seismic Survey Operation
Authors: Grindheim Jan Vidar , Welker Ken E. , Revhaug Inge 
Published: November 2019

Abstract
Seismic surveys for petroleum exploration employ a number of towed cable streamers of lengths in the order of 3∼12 km. Accurate positioning is important both for navigation and control of the streamer spread and for seismic data processing. In the present study, a numerical streamer model based on a Finite Element Method is implemented both as an Extended Kalman filter and an Ensemble Kalman filter. The streamer model includes features such as tailbuoy, locally estimated sea current introduced at each node, control bird inputs, cable stretch and tension. The filter implementations are intended to blend the streamer model with observations such as acoustic range measurements and satellite navigation positioning. The implementations have been compared and validated employing full scale data for two line changes. The purpose is to investigate the filters’ performance during periods with poor or missing observations.
Path Following and Collision Avoidance of Underactuated Marine Vessels Based on MPC Design
Authors: Zheng Guoping , Liu Cheng , Li Cheng 
Published: November 2019

Abstract
Path following of underactuated marine vessels is a fundamental marine practice in shipping industry. However, the collision avoidance, which is frequently encountered during the process of path following of ships sailing in seaways, is neglected in traditional studies of path following. In this paper, a novel control design for path following with auxiliary system for collision avoidance is presented. Taking advantage of the capability of dealing with multi-variable system with the constraints, the model predictive control (MPC) method is employed to deal with the input saturation (rudder) and underactuated problem. Furthermore, the parallel computational nature of projection neural network (PNN) is included to reduce the computational burden of traditional MPC technique and make the control design more efficient. Simulations are conducted to validate the effectiveness and efficiency of the proposed control design.
Designing Coastal Structures for Tsunami Loads per ASCE 7-16
Authors: Robertson Ian N. , McKamey Jacob 
Published: November 2019

Abstract
The 2016 edition of ASCE 7, Minimum Loads and Associated Criteria for Buildings and Other Structures, contains a brand new Chapter 6 on Tsunami Loads and Effects. This new chapter applies to the tsunami design of all Risk Category III (high occupancy) and IV (essential) buildings, and potentially many taller Risk Category II (regular) buildings, in coastal communities in Alaska, Washington, Oregon, California and Hawaii. These provisions can also be applied to other communities exposed to tsunami hazard, including Guam, American Samoa, Puerto Rico, and communities outside the US.
This paper shows an example of how the new tsunami design provisions would apply to the design of prototypical multi-story coastal reinforced concrete buildings at different locations on the US Pacific Coast. The prototypical Risk Category II buildings are located in Seaside OR, Monterey CA, Waikiki HI and Hilo HI. Economic consequences of including tsunami design for mid- to high-rise Risk Category II buildings are discussed.
Fracture Mechanics Based Mooring Fatigue Analysis for a Semi-Submersible Subjected to Triple Narrow-Band Loading Processes
Authors: Xue Xutian , Chen Nian-Zhong , Pu Yongchang 
Published: November 2019

Abstract
In the general offshore operating locations, mooring systems are normally considered to be primarily affected by environmental loadings induced by waves, wind and current. WF motion induced by first-order waves, LF motion induced by second-order waves and wind would make the most contribution to the fatigue damage of mooring lines. However, it was reported recently that in the Gulf of Mexico (GoM), the fatigue life of mooring lines can be significantly affected by the vortex induced motion (VIM) induced by loop current. The aim of this presented paper is to address the influence of VIM on fatigue life of the mooring system operating at the central of the GoM through performing a fracture mechanics (FM) based fatigue analysis for an offshore mooring system.
A frequency-domain mooring analysis for the semi-submersible is conducted where WF motion induced by first-order waves, LF motion induced by second-order waves and wind, and VIM induced by loop current are taken into account. WF motion, LF motion and VIM are treated as three independent loading processes. A wide-band loading combination method is then used for predicting the loading processes acting on the mooring system combining WF motion, LF motion and VIM. A fracture mechanics based analysis is performed to examine the fatigue life of mooring system, in which initial surface cracks in previous existence are assumed to grow from the surfaces of mooring chain links connecting to the fairleads. The stress intensity factor ranges to estimate the crack growth in the FM based analysis are obtained from a finite element (FE) analysis.
Quantitative Evaluation of Ship Operational Effect in Actually Encountered Sea States
Authors: Miratsu Rei , Fukui Tsutomu , Matsumoto Toshiyuki , Zhu Tingyao 
Published: November 2019

Abstract
Since ships are being operated under consideration of the safety for lives and properties, economical reasons and so on, the sea states in natural phenomena and those actually encountered by ships are thought to be different, the latter has some effects of human operational factors (called as “ship operational effect”). Evaluating the ship operational effect in detail is important to consider rational wave design loads for hull structure strength.
The purpose of this study is to evaluate the ship operational effect in actually encountered sea states quantitatively. As the first report, comparison was made between IACS Rec.34 (a kind of the observed sea states in natural phenomena) and forecasted sea states corresponding to AIS data of ships (a kind of the sea states data actually encountered by ships) on the North Atlantic. Comparisons among the encountered significant wave heights by merchant ships such as bulk carriers, oil tankers and container ships and those specified in IACS Rec. 34 were carried out. Furthermore, the wave headings regarding the encountered waves were investigated. Finally, the relationships between encountered significant wave heights and ship speeds were derived to confirm the ship operational effect.
It was confirmed from the results that the actually encountered wave heights were smaller than those in IACS Rec. 34, through comparing the exceedance probability of the significant wave heights for each type of ships and IACS Rec. 34. The exceedance probability in the encountered beam seas is relatively lower compared with those in the encountered head and following seas. The results also show that ship speeds decrease when the encountered wave heights become larger.
Slamming Force Contribution due to Plunging Breakers on Circular, Square and Diamond Cylinders
Authors: Wang Xin , Dev Arun Kr , Tao Longbin , Chia De Wang , Zhang Yali 
Published: November 2019

Abstract
Plunging breakers, unlike non-breaking waves, impose additional slamming load on the offshore structures. This additional slamming load is considered an extreme event and is one of the most devastating forces that an offshore structure could encounter during its operational lifecycle.
Whilst there are design guidelines for offshore structures pertaining to breaking waves, however it is limited to only cylindrical shape. The amount of slamming load contribution by the plunging jet is also dependent on the cross section geometries of the offshore structures. Different geometries would give rise to different air entrainment phenomenon during wave breaking and therefore affecting the slamming load contributions.
In this research, JONSWAP spectrum was used to create plunging breakers via the focusing method at Newcastle University’s Wind Wave and Current tank. The crux of this research is to investigate the wave-breaking impact load on cylindrical structures with different cross section geometries commonly used in the offshore industry.
A Fast 3D Model for Annular Flows of Wellbore Completion Fluids
Authors: Tardy Philippe M. J. 
Published: November 2019

Abstract
This paper presents a novel approach to solving the 3D flow and displacement of completion fluids in the annulus formed by the gap between the outer wall of the casing and the wellbore rock face. Completion fluids displace each-other and follow a complex path promoted by rheology and density contrasts, casing movement and by the shape and orientation of the annulus. Muds and cement slurries often exhibit a yield stress, an additional challenge for optimal mud removal and cement coverage. This work extends previously published 2D models, to now capture fluid distribution and velocity profiles across the gap width in the 3D axial-azimuthal-radial space, at a lower computer cost than with conventional 3D CFD approaches. This gain is obtained by solving a 2D-only pressure equation for calculating the 3D annular flow, under the so-called narrow-gap approximation.
Strength and Fatigue Performance of Steel Lazy Wave Risers With Change in Configuration Parameters
Authors: Lal Mayank , Wang Feng , Lu Xiaohua , Sebastian Abhilash 
Published: November 2019

Abstract
Steel Lazy wave risers are being increasingly used for deep water applications due to better strength and fatigue performance in the touchdown zone compared to steel catenary risers. Several parameters govern the design of steel lazy wave risers including the length of the catenary from hang-off to start of buoyancy section and the length of the buoyancy section. In this paper, a parametric study is performed to investigate the trends in strength and fatigue performance of steel lazy wave risers with change in configuration parameters. A normative cost assessment is also performed to show the impact of these design variables on overall cost of the system.
Dynamic analysis is performed to check the change in strength and fatigue performance of steel lazy wave risers as the configuration parameters are changed. The results from the parametric study will assist in designing steel lazy wave risers which satisfy the strength and fatigue design criteria.
Data Mining for Estimating Fatigue Strength Based on Composition and Process Parameters
Authors: Keprate Arvind , Ratnayake R. M. Chandima 
Published: November 2019

Abstract
Accurately estimating the fatigue strength of steels is vital, due to the extremely high cost (and time) of fatigue testing and often fatal consequences of fatigue failures. The main objective of this manuscript is to perform data mining on the fatigue dataset for steel available from the National Institute of Material Science (NIMS) MatNavi. The cross-industry process for data mining (CRISP-DM) approach was followed in the paper, in order to gain meaningful insights from the dataset and to estimate the fatigue strength of carbon and low alloy steels, using composition and processing parameters. Of the six steps of the CRISP-DM approach, special emphasis has been placed on steps 2 to 5 (i.e. data understanding, data preparation, modeling and evaluation). In step 4 (i.e. modeling), a range of machine learning (parametric and non-parametric) is explored to predict the fatigue strength, based on the composition and process parameters. Various algorithms were trained and tested on the dataset and finally evaluated, using metrics such as root mean square error (RMSE), Mean Absolute Error (MAE), Coefficient of Determination (R2) and Explained Variance Score (EVS).
Impact of Simulation Duration for Offshore Floating Wind Turbine Analysis Using a Coupled FAST-OrcaFlex Model
Authors: Pillai Ajit C. , Thies Philipp R. , Johanning Lars 
Published: November 2019

Abstract
This paper uses a coupled FAST-OrcaFlex model in order to explore the impact of simulation duration on model convergence. The work analyses both operational and extreme cases, assessing the estimated fatigue and extreme loads experienced by a floating offshore wind turbine and its mooring system. Considering an OC4 semi-submersible deployed with the NREL 5 MW turbine, the case study performs a parametric sweep over a range of wind speeds, sea states, and simulation durations. Through this sweep, the paper establishes the impact of the simulation duration for this particular floating offshore wind turbine and characterizes the convergence properties of the loads and excursions as a function of the simulation duration. The results inform the selection of simulation durations to be used in coupled aero-hydro models and optimization frameworks for floating offshore wind applications and can be used to aid the development of guidance and standards for coupled floating offshore wind turbine models.
The Branched Riser Systems: Concept Development
Authors: Ogbeifun Achoyamen Michael , Oterkus Selda , Race Julia , Naik Harit , Decnop Eduardo , Dakshina Moorthy 
Published: November 2019

Abstract
A new riser system concept is being investigated for deep-water application. This is the Branched Riser Systems with its three types: the Branched Steel Catenary Riser (BSCR) System, the Branched Steel Lazy Wave Riser (BSLWR) System and the Branched Lazy Wave Hybrid Riser (BLWHR) Systems. The branched riser system consists of a large bore pipe, which is terminated at an optimized water depth considering the minimum wall thickness requirement from burst and collapse criteria. The larger bore riser pipe is extended from this cut off water depth to the seabed by two smaller riser pipes via a connecting component (connector). The concept draws benefits from the performance of smaller riser bore pipe in strength and fatigue performance besides the opportunities provided by larger bore pipe for maximum flow throughput and vessel top decongestion.
Preliminary results from ongoing investigation of type 1 (BSCR) of the branched riser systems, using a 12-inch pipe in combination with two 8-inch riser pipes in a water depth of 3,000m for a cut off water depth of 1500m, indicates a reduction in overall riser weight, stress utilization and fatigue damage at the riser hang off (HO) and touch down zone (TDZ). Results obtained indicate that possible benefits can be achieved through a combination of advantages of smaller and larger bore riser pipe and justifies further research interest on the novel riser concept.
A New Three-Layer Model for Gravel Packing Applications in Horizontal Wells
Authors: Sarraf Shirazi Alireza , Frigaard Ian 
Published: November 2019

Abstract
In [1] we have developed a modified three-layer model for solid-liquid flow in horizontal pipes, which overcomes the limitations of previous mechanistic models. The steady-state model predicts the pressure loss, critical velocity, concentration profile in the heterogeneous layer, mean heterogeneous layer and moving bed layer velocities, and bed layer heights for each set of parameters. The steady-state model predictions show very good agreement with experimentally measured results in the literature.
In this paper we extend the steady-state three-layer model to annular geometries and apply it to the design of open-hole gravel packing operations, in the typical parameter ranges of gravel packing operations for alpha wave placements. Alpha wave design is a key factor for successful gravel packing, and the models typically used are either based on small-scale experiments or are not specifically developed for gravel packing, e.g. cuttings transport models. In gravel packing the hydraulic configuration is slightly different. We explain how bed height is selected via coupling between the inner and outer annuli and from the outer annulus hydraulics. We investigate the effects of important parameters such as the slurry flow rate, mean solids concentration, wash pipe diameter, etc. on gravel packing operations.
Dynamic Response of a Large-Diameter Monopile Considering 35-Hour Storm Conditions
Authors: Bachynski Erin E. , Page Ana , Katsikogiannis George 
Published: November 2019

Abstract
As a part of the assessment of foundation resistance for monopiles, several offshore wind standards prescribe symmetric 35-hour (or 42-hour) storm sequences in terms of wind speed and significant wave height. The temporal evolution of the peak period is not specified explicitly in the standards, despite the fact that large monopile wind turbines are sensitive to the wave period. In the present work, the storm sequences according to the standards are first compared to hindcast data for intermediate water depth locations in the North Sea. An alternative storm sequence is proposed based on the hindcast data, and possible values of the peak period evolution are proposed for the standard models. The responses of a 10 MW monopile wind turbine are then computed for both the standard and proposed sequences using a time domain aero-hydro-servo-elastic code coupled to a macro element model for the soil-structure interaction. The resulting mudline load cycles are then compared for the different storm sequences.
URANS Predictions of Low-Frequency Damping of a LNGC
Authors: Jaouën Frédérick , Koop Arjen , Vatinel Lucas 
Published: November 2019

Abstract
The horizontal motions of a moored offshore structure in waves are dominated by the resonance phenomena that occur at the natural frequencies of the system. Therefore, the maximum excursions of the structure depend on both the wave loads and the damping in the system. At present, potential flow calculations are employed for predicting the wave loads on offshore structures. However, such methods cannot predict hydrodynamic damping which is dominated by viscous effects. Therefore, the current practice in the industry is to obtain the low-frequency damping based on model testing. Nowadays, CFD simulations also have the potential to predict the low-frequency viscous damping of offshore structures in calm water. To obtain confidence in the accuracy of CFD simulations, a proper validation of the results of such CFD calculations is essential.
In this paper, the flow around a forced surging or swaying LNGC is calculated using the CFD code ReFRESCO. The objective is to assess the accuracy and applicability of CFD for predicting the low-frequency viscous damping. After a description of the code and the used numerical methods, the results are presented and compared with results from model tests. Both inertia and damping coefficients are analyzed from the calculated hydrodynamics loads. Extensive numerical studies have been carried out to determine the influence of grid resolution, time step and iterative convergence on the flow solution and on the calculated damping. The numerical uncertainty of the results are assessed for one combination of amplitude and period for the surge motion. The CFD results are compared to experimental results indicating that the calculated damping coefficients agree within 5% for both surge and sway motion.