bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic Positioning System: Systematic Weight Assignment for DP Sub-Systems Using Multi-Criteria Evaluation Technique Analytic Hierarchy Process and Validation Using DP-RI Tool With Deep Learning Algorithm
Authors: Fernandez Charles , Dev Arun Kr. , Norman Rose , Woo Wai Lok , Kumar Shashi Bhushan 
Published: November 2019

Abstract
The Dynamic Positioning (DP) System of a vessel involves complex interactions between a large number of sub-systems. Each sub-system plays a unique role in the continuous overall DP function for safe and reliable operation of the vessel. Rating the significance or assigning weightings to the DP sub-systems in different operating conditions is a complex task that requires input from many stakeholders. The weighting assignment is a critical step in determining the reliability of the DP system during complex marine and offshore operations. Thus, an accurate weighting assignment is crucial as it, in turn, influences the decision-making of the operator concerning the DP system functionality execution. Often DP operators prefer to rely on intuition in assigning the weightings. However, it introduces an inherent uncertainty and level of inconsistency in the decision making. The systematic assignment of weightings requires a clear definition of criteria and objectives and data collection with the DP system operating continuously in different environmental conditions. The sub-systems of the overall DP system are characterized by multi-attributes resulting in a high number of comparisons thereby making weighting distribution complicated. If the weighting distribution was performed by simplifying the attributes, making the decision by excluding part of them or compromising the cognitive efforts, then this could lead to inaccurate decision making.
Multi-Criteria Decision Making (MCDM) methods have evolved over several decades and have been used in various applications within the Maritime and Oil and Gas industries. DP, being a complex system, naturally lends itself to the implementation of MCDM techniques to assign weight distribution among its sub-systems. In this paper, the Analytic Hierarchy Process (AHP) methodology is used for weight assignment among the DP sub-systems. An AHP model is effective in obtaining the domain knowledge from numerous experts and representing knowledge-guided indexing. The approach involved examination of several criteria in terms of both quantitative and qualitative variables. A state-of-the-art advisory decision-making tool, Dynamic Positioning Reliability Index (DP-RI), is used to validate the results from AHP. The weighting assignments from AHP are close to the reality and verified using the tool through real-life scenarios.
Evaluation of an Equivalent Design Wave Method to Define Lifetime Combined Loading Scenarios for Trimarans
Authors: Seyffert H. C. , Kana A. A. 
Published: November 2019

Abstract
The evaluation of marine system reliability requires the definition of the most extreme loading that a vessel is expected to experience. To quantify the risk levels associated with a full ship lifetime, some decisions must be made about which vessel scenarios are worth analyzing, i.e. the worst-case vessel scenarios. The problem is further complicated when considering extreme combined loading on a novel hull form such as a trimaran. To evaluate structural compliance with given acceptance criteria many classification societies suggest defining simultaneous load combination cases by an Equivalent Design Wave (EDW) method for use in a finite element model. This paper examines whether the EDW approach defines realistic lifetime combined loading scenarios specifically for a novel hull form like a trimaran.
A Three-Dimensional FE Approach for the Stress Analysis of Tensile Armors Inside End Fittings
Authors: Miyazaki Marcelo N. R. , de Sousa José Renato M. , Ellwanger Gilberto B. 
Published: November 2019

Abstract
In this work, a solid three-dimensional finite element (FE) approach is proposed to investigate the stress distribution along the tensile armors of flexible pipes inside their end fittings (EFs). This approach employs two different models. The first model consists of a single tensile armor, which is meshed with solid FEs, and a rigid surface that represents the EF. A toroidal template is also considered and the EF mounting process is simulated. In the second model, the deformed armor and the stress state from the first model are considered and the voids between the armor and the EF are filled with resin, which is also modeled with solid FEs. Geometric and material nonlinearities are addressed and the interaction between the different components are ensured with contact elements. A case study is conducted to observe the stress distribution along the tensile armor considering typical operational loads. The results obtained are compared to those calculated with a previously proposed analytical model showing good agreement, but also evidencing the need to adequately simulate the EF mounting process and the pre-operational tests. Moreover, intense stress concentrations at the entrance of the EF are observed thus indicating that this region can be critical in fatigue analyses.
A Symbolic Regression Formulation to Estimate the Lateral Buckling Resistance of Tensile Armors in Flexible Pipes
Authors: Gonzalez Gabriel M. , de Sousa José Renato M. , Sagrilo Luis V. S. , Martins Ricardo R. , Rocha Djalene M. 
Published: November 2019

Abstract
In this work, a previously proposed finite element is applied in conjunction with a modal approach to predict the lateral buckling resistance of the tensile armors in flexible pipes. The finite element represents the mechanical behavior of tensile armors settled on elastic foundations, which model the frictional interaction between these armors and the surrounding layers. This FE modal approach is used to evaluate the buckling response of 44 different tensile armors considering 15 different friction coefficients between layers. The responses obtained formed a dataset employed in symbolic regression analyses that led to an analytical formulation capable of adequately reproducing the numerical results with minimum computational effort. The results obtained with this analytical formulation are compared to those from other numerical models and experimental measurements showing good agreement and evidencing the potential of the proposed formulation.
Prediction of Liner Wrinkling During High Strain Bending of Mechanically Lined Pipe
Authors: Pépin Aurélien , Tkaczyk Tomasz , Martinez Michael , O’Dowd Noel , Nikbin Kamran 
Published: November 2019

Abstract
A high demand for transport of corrosive fluids subsea has generated interest in solid corrosion resistant alloy (CRA) and bi-metal pipes. Bi-metal pipes, including hot-roll bonded (HRB) clad and mechanically lined pipes (MLP), are made of a carbon steel (CS) pipe lined with a CRA layer. Mechanically lined pipes, where the CRA liner is held inside the host pipe by means of an interference fit, offer shorter lead times and are considerably more economical than equivalent solid CRA and HRB clad pipes with a metallurgical bond between CS and CRA layers.
Reel-lay is a cost-effective method for installing subsea pipelines up to 18” (457.2 mm) in diameter. However, plastic straining associated with reeling may trigger wrinkling of the CRA liner. Two approaches for safe installation of reeled MLPs have therefore been proposed: pressurised and non-pressurised reeling.
This paper focuses on reel-lay installation at atmospheric pressure. Nevertheless, the numerical analysis framework presented is also applicable to MLPs installed at elevated pressure in a scenario where they are subjected to bending after being depressurised. Small-scale mechanical tests were carried out to assess the effect of manufacturing and cyclic plastic bending on the tensile behaviour of the CRA liner. After full-scale bending trials had been undertaken, they were simulated numerically to demonstrate the suitability of the proposed numerical approach for predicting liner separation from the host pipe and subsequent wrinkling during high strain bending. To improve ovality prediction, which governs liner separation and wrinkling, the authors developed an advanced metal plasticity model.
Two-Phase MPS Method for Dam-Break Flows
Authors: Wen Xiao , Wan Decheng 
Published: November 2019

Abstract
In this paper, the dam-break problem is numerically simulated using two-phase moving particle semi-implicit (MPS) method. Firstly, the two-phase MPS method is extended from single-phase MPS method. The present method treats the multiphase system as a multi-density and multi-viscosity fluid, and a single set of equations could be used for the whole system. The interaction between particles of different phases is considered through the applications of inter-particle viscosity and density smoothing technique. The two-phase MPS method is then successfully applied to violent dam-break problem. The numerical results obtained by single-phase and two-phase method are both compared with experimental results in the open literature. The characteristics of air cavity are analyzed, including the pressure inside the cavity and the cavity shape deformation.
Numerical Study on Aero-Hydrodynamics With Inter-Turbine Spacing Variation for Two Floating Offshore Wind Turbines
Authors: Huang Yang , Wan Decheng 
Published: November 2019

Abstract
To investigate the influence of the inter-turbine spacing on the performance of the floating offshore wind turbine (FOWT) in the floating wind farm, coupled aero-hydrodynamic simulations of two spar-type FOWT models with inter-turbine spacing variation under shear wind and regular wave conditions are performed in the present work. An unsteady actuator line model (UALM) is embedded into in-house code naoe-FOAM-SJTU to establish a fully coupled CFD analysis tool for numerical simulations of FOWTs. From the simulation results, the unsteady aerodynamic power and thrust are obtained, and the hydrodynamic responses including the six-degree-of-freedom motions and mooring tensions are available. Detailed flow visualizations of wake velocity profiles and vortex structures are also illustrated. The coupled performance of floating offshore wind turbines with inter-turbine spacing variation are analyzed, and the influences of inter-turbine spacing on aero-hydrodynamic characteristics of coupled wind-wave flow field are discussed. It is found that the power output of downstream wind turbine increases with inter-turbine spacing. Coupled aero-hydrodynamic characteristics of flow filed are significantly affected by inter-turbine spacing.
Developing Sensitivity Response Curves to Evaluate Mechanical Integrity of Set Cement
Authors: Patel Harshkumar , Salehi Saeed , Teodoriu Catalin 
Published: November 2019

Abstract
Cement sheath is an important barrier element for maintaining well integrity. Poor quality cement has often been cited as one of the major causes for loss of well control events. This paper presents a useful approach for quick assessment of fitness for service and mechanical integrity of cement sheath.
For this study, three dimensional finite element models consisting of concentric casings and annular cement sheath were created. Different wellbore and annular pressure loads were applied. Performance of cement sheath was assessed by analyzing radial, hoop, axial, and maximum shear stresses for mechanical failure. The FEA model was validated by analytical calculation of the stresses.
Parametric study was performed by individually varying influencing factors such as — cement sheath material properties, its dimensions, and wellbore pressure loads. Sensitivity response curve was developed by normalizing influential parameters and representing them against a mechanical stress on the same plot. The plot can be used to estimate whether cement will structurally fail due to various operational wellbore pressure changes, or variation in material properties caused by aging or temperature changes. The plot can also be utilized to identify the most critical factors influencing cement’s performance.
This paper presents a simple and effective approach of developing sensitivity response curves for a set cement sheath. Industry standards or guidelines can be improved by adding sensitivity response curves for standard cement recipes. This can help design engineers, and regulators alike in quickly evaluating short-term or long-term “fitness for service” of cement sheath from structural integrity perspective.
Vortex Shedding and Roll Damping for Hulls With Rounded Bilges
Authors: Milne Ian A. , Tong Feifei , Graham J. Michael R. 
Published: November 2019

Abstract
Vortex shedding and eddy generation can provide a substantial contribution to the hydrodynamic roll damping of vessels. While sharp-edge bilge geometries generally result in greater damping, a more rounded bilge may be beneficial for the other ship motions and mooring design. To this end, the effect of the bilge rounding on the vortex shedding dynamics and the hydrodynamic damping of hulls is investigated numerically. A series of new computations of the response of hulls with differing bilge radii and subject to forced oscillatory motion are reported. The severity of the vortex shedding and the magnitude of the damping is shown to depend strongly on the bilge geometry. Computations using an efficient isolated edge discrete vortex model are also found to be generally in qualitative agreement with the CFD results. The results extend the relatively scarce literature on the effect of bilge rounding and can assist in informing hull design and concept selection.
Optimization of Temporary Plugging Parameters Under Rough Fractures
Authors: Yuan Lishan , Zhou Fujian , Li Ben , Gao Junjie , Wang Caizhong , Tan Yanxin , Huang Jianbo 
Published: November 2019

Abstract
Temporary-plugging-and-diverting (TPD) fracturing technology is widely used in the development of the unconventional reservoir. The operational procedure of temporary plugging and the size and combination of diverters are very much concerned by field engineers. This study compares different pumping procedure of diverters and optimizes the combination and pumping rate of diverters under the different width of the fracture. The experimental method is based on a simulated fracture apparatus, which is manufactured by the 3D printing technology. The surface morphology of the fracture is obtained through a 3D scanning of a fracture. The experimental procedure is pumping the carrier liquid and diverter mixtures into the fracture while recording pumping pressure and the outlet volume of carrier fluid. The fracture plugging efficiency was evaluated through the recorded parameters. The diverter concentration and composition were optimized at a wide range of fracture width (1 mm to 4 mm). Low the diverter concentration could help to reduce the operational risk of the diversion. Under the low concentration of the diverters, the plugging mechanism is that the large particle diverters bridge in the fracture due to the fracture tortuosity and roughness; the smaller particle and fiber diverters then fill the voids of the large particles and form a strong and low permeable diverter pack. The results indicate that pumping the mixture particle and fiber diverters are more beneficial to plug the fracture than pumping them separately and sequentially. High particle concentration has a two-sided effect, which leads to the existence of an optimal fiber-to-particle ratio. The concentration of diverters could decrease when the size of diverters is increased. At a constant fracture width, higher pumping rates can help to temporarily plug the fracture more efficiently.
Efficiency of Carbon Fibre Buckle Arrestors for Subsea Pipelines
Authors: Karampour Hassan , Alrsai Mahmoud , Hall Wayne 
Published: November 2019

Abstract
This paper experimentally investigates the feasibility and efficiency of using Carbon Fiber Reinforced Polymer (CFRP) buckle arrestors in controlling the buckle propagation failure of subsea pipelines. Hyperbaric chamber tests are conducted on 1.6m Steel pipe with D/t = 28 and using CFRP buckle arrestors with different thickness, fiber orientation and spacing. Using an external pressure gauge and a high-pressure camera inserted inside the hyperbaric chamber, the pressure magnitude, rate and shape of collapse and its propagation in the vicinity of the arrestors are measured. The dynamics of buckle propagation and efficiency of different arrestor configurations are reported.
It is observed that in the vicinity of the CFRP arrestors wrapped in the hoop direction, the well-known dog-bone buckle shape changes into a U-shape and the pressure level upsurges significantly. The optimum results were obtained with CFRP as thick as the pipeline wall-thickness and wrapped in the hoop direction of the pipeline. The results show that at similar arrestor efficiency, the CFRP arrestors can be much thinner than the existing steel slip-on arrestors. Also, the spacing between the CFRP arrestor can be larger than that of the steel slip-on arrestor.
Finite Element Analysis of Seafloor-SCR Interaction in Touchdown Zone
Authors: Wei Zhang , Peng Peng 
Published: November 2019

Abstract
The touch down zone (TDZ) of steel catenary riser (SCR) is subject to fatigue damage. As a significant fatigue indicator, the variation of the stress range largely depends on the instantaneous changing bending moment. In this paper, a non-linear interaction model between seafloor and SCR is developed to consider the formation of trench at TDZ and its effect on the variation of bending moment. The seafloor soil is modeled by the nonlinear springs, whose stiffness is calculated according to nonlinear load-deflection relationship, such that the effect of cyclic loading can be simulated. The modeling of trench evolution and bending moment variation near the touchdown point (TDP) under cyclic loading are further conducted using the finite element software ABAQUS. The results show that the trench shaping is related to the uplift displacement of SCR and its number of cycles. The dependence of the bending moment on the displacement cycles near TDP is also investigated.
Review and Comparison of Collated Offshore Mooring Chain Fatigue Test Data
Authors: Farrow Gary H. , Potts Andrew E. , Jal Eric , D’Arcy Evans Nicholas , Kilner Andrew A. 
Published: November 2019

Abstract
The first phase of the Chain FEARS (Finite Element Analysis of Residual Strength) Joint Industry Project (JIP) aimed to develop guidance for the determination of a rational discard criteria for mooring chains subject to severe pitting corrosion which, based on current code requirements, would otherwise require immediate removal and replacement. Critical to the ability to evaluate the residual fatigue life of a degraded chain, is to have an accurate estimate of the chain in its as-new condition, thereby providing a benchmark for any loss in fatigue life associated with severe corrosion or wear.
A large collection of fatigue test data was collated for comparison and to establish underlying trends in as-new mooring chain fatigue response, and a non-linear multi-axial Finite Element Analysis (FEA) fatigue assessment method was developed to correlate against available as-new chain link fatigue test data and underlying failure trends [1,2] as part of the JIP achieving this critical requirement.
This study sought through collation and review of available fatigue test data to:
• Identify relationships between chain fatigue performance and the key input parameters of chain type, grade and environmental conditions.
• Compare and validate the fatigue test data against the current Code formulations for chain fatigue endurance.
• Determine chain nominal stress S-N fatigue endurance curves against which to validate a numerical model developed as part of the Chain FEARS JIP for the assessment of as-new chain link fatigue endurance.
The collated fatigue data was separated into groups associated with offshore mooring chain type (i.e. stud and studless), grade (i.e. ORQ, R3, R4 and R5) and environmental conditions (i.e. free corrosion in seawater and in-air) for review.
Good correlation occurred between the two standard deviation lower bound of the mean curves and current Code formulation design curves. The mean curves of the collated fatigue test data were considered representative of the overall fatigue performance of chain links and as such formed a good basis for subsequent development and the validation of an FEA model for the assessment of chain fatigue endurance [1,2].
Development of Flexible Composite Pipe Cross-Section Design Software Based on Visual Basic
Authors: Sun Xinyu , Bai Yong , Zhao Jiannan , Liu Chang , Zhang Xiaojie 
Published: November 2019

Abstract
With the rapid development of science and information technology, software systems are widely used in all walks of life in society. Composite materials have become the hotspot and trend in pipe development, which greatly broaden the application field of composite pipes. Aiming at the requirement of composite pipe section design in composite flexible pipe factories in actual production, this paper simplifies the flexible composite pipe into a uniform continuous model, and develops a pipe section design software based on Visual Basic environment. According to the numerical calculation method in mechanics and the empirical formula, considering the production error and safety factor, this paper puts forward a reasonable method for designing the flexible composite pipe section, and develops a system for calculating it using Visual Basic. Based on the performance of raw materials and the requirement of customers for pipe pressure, this software can figure out the section data of steel strip pipe, steel cord pipe, polyester pipe, Kevlar pipe, and fiberglass pipe respectively, and obtain the design pressure, minimum bending radius and other parameters, thus improving the efficiency of the design process. At the same time, raw material quotation and pipe cost price can be calculated to facilitate the purchase of raw materials, pipe storage and sales. This software is an ideal tool for calculating flexible composite pipe cross-section data.
A Novel Semi-Submersible Floating Wind Turbine Platform Design Based on Tuned Liquid Column Dampers
Authors: Mao Baijin , Sun Jili , Tang Zecheng , Feng Bo , Zhang Weijie , Zhang Dahai , Si Yulin 
Published: November 2019

Abstract
Floating offshore wind turbine (FOWT) has been a hot research topic in recent years due to its great potential in deep sea wind energy harvesting. However, the floating platforms will introduce additional degrees of freedom to the system, which results in much more ultimate and fatigue loads onto the wind turbine structure compared with fixed bottom types. The load issue has been the major design challenge in developing FOWTs.
In this paper, we report a novel semi-submersible supporting platform design, named MUsupport, aiming to improve the dynamic responses and reduce loads for FOWTs. The proposed semi-submersible MUsupport is mainly composed of one main column attached to the tower and four offset columns. Particularly, instead of simply filled with ballast water, the four columns act as four tuned liquid column dampers (TLCDs), and the oscillating liquid inside the TLCDs is supposed to help improve the dynamic responses of the semi-submersible platform, thus reducing the loads. The sizing of these TLCDs are determined by frequency analysis, and the detailed structural properties for MUsupport are described in this paper. Additionally, in order to better study the damping effects of the TLCDs, the dynamic model of MUsupport FOWT in the pitch-surge-heave plane is derived based on the Lagrangian approach, and free decay simulation test is performed. It can be observed from the results that the introduction of TLCDs will bring more damping to the system dynamics, which is helpful for FOWT load reduction. Note that this is only preliminary study, and future works will comprehensively investigate its hydrodynamic and mooring behaviors of MUsupport, and aero-hydro-servo-elastic numerical simulations or experimental tests should be performed to further verify its effectiveness.