bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of Metal Seals With for Interval Control Valve With Roundness Error Intelligent Well Considering Roundness Error
Authors: Yang Yiwei , Zhu Hongwu , Yang Yiwei , He Dongsheng , Zheng Yan , Li Chuan , Xu Liangbin , He Yufa 
Published: December 2020

Abstract
Intelligent wells armed with the interval control valve (ICV) are more and more widely applied in the oilfields. In an ICV, the metal seal pair composed of the metal seal ring and the sliding sleeve is designed to isolate the produced fluid flow between the casing annulus and the tubing. The evaluation of the metal seals for ICVs is necessary to enhance the reliability. In this paper, the influences of medium pressure and initial interference on the contact mechanical behaviors of the metal seal for the ICV are studied by using finite element analysis (FEA) when both of the metal seal pair elements have roundness errors. The results indicate that when the both long axes of the metal seal pair’s elliptical sections coincide or are orthogonal, the contact stresses on the core area for the seal face present cosine or sine curve distributions. Each distribution curve becomes smoother with the increase of medium pressure, initial interference or the reduction of sliding sleeve roundness error. And for the contact stress distribution curves, the maximum at the peaks and troughs and the average increase with the increase of the medium pressure, the initial interference and the roundness error of the sliding sleeve. Moreover, when the angle between the metal seal pair elliptical sections’ long axes increases from 0 ° to 90 °, the contact stress distribution curves on the core area for the seal face change from cosine to sine type, and the maximum at the peaks and troughs and the average first decrease and then increase. The relationship curves between the maximum or average contact stress and the angle of two long axes are approximately symmetrical about the line θ = 45° . This paper provides a simulation evaluation for the ICV metal seal pair with roundness error.
Spatial Features of Extreme Waves in Gulf of Mexico
Authors: Wada Ryota , Jonathan Philip , Waseda Takuji 
Published: December 2020

Abstract
Extreme value analysis of significant wave height using data from a single location often incurs large uncertainty due to small sample size. Including wave data from nearby locations increases sample size at the risk of introducing dependency between extreme events and hence violating modelling assumptions. In this work, we consider extreme value analysis of spatial wave data from the 109-year GOMOS wave hindcast for the Gulf of Mexico, seeking to incorporate the effects of spatial dependence in a simple but effective manner. We demonstrate that, for estimation of return values at a given location, incorporation of data from a circular disk region with radius of approximately 5° (long.-lat.), centred at the location of interest, provides an appropriate basis for extreme value analysis using the STM-E approach of Wada et al. (2018).
Consistent State Space Modelling of Hydrodynamic Memory
Authors: Kaasen Karl E. 
Published: December 2020

Abstract
The conventional way to model hydrodynamic memory or radiation force is to use retardation functions. These functions are usually derived from frequency-dependent damping functions that are calculated by a diffraction-radiation code using potential theory. Calculating the retardation functions can be challenging due to lack of information at high frequency. In simulation of wave-driven vessel motion the retardation function is convolved with the velocity to give the wave radiation force, which is time-consuming. The paper describes how the memory effects can be modelled consistently by linear differential equations, such that coupled modes of motion share one set of poles.
The coefficients of the differential equations are found by least squares fitting of a certain rational function to the numerical damping function. One advantage of this is that no assumption need to be made about the added mass at infinite frequency. Nor is any conditioning of the given data necessary.
Using the fitted model in time-domain simulation is much quicker than using retardation functions. The method is applied to data representing the sway, roll and yaw motions of an FPSO of 238 m length. It was found that a sixth-order differential equation model fitted the given numeric radiation function well.
It is shown how the high frequency asymptote for added mass can be estimated with high accuracy, which is valuable when it is not known in advance.
Study of Hot Cracking on Automatic Tandem Butt Welding
Authors: Maeda Shintaro , Shibahara Masakazu , Nishihara Kensaku , Takeda Hiroyuki , Miwa Tsuyoshi , Yamazaki Kei , Morimoto Tomokazu , Ma Ninshu 
Published: December 2020

Abstract
In recent years, ship hulls have become larger. And the welding has become more important technology in ship building. In other word, welding has become more important technology in shipbuilding. In Japanese shipbuilding, multiple electrode butt welding has been performed with large current and high speed to increase construction efficiency. However, the multiple electrode welding method may cause a hot cracking. X-ray or ultra sonic wave inspection and repair welding are necessary due to the generation of hot cracking. These will increase the production cost. Therefore, it is important to prevent hot cracking. It is known that hot cracking is generated by both metallurgical and mechanical factors. The authors propose a new evaluation method of hot cracking based on the modeling of both mechanical and metallurgical behaviors. In the developed method, from the metallurgical point of view, solidification growth direction is determined from the temperature gradient obtained by the heat conduction analysis to predict the position of hot cracking. Moreover, from the mechanical point of view, the possibility of the generation of hot cracking is assessed using plastic strain increment in Brittleness Temperature Range (BTR). In order to show the validity of the developed method, the developed method is applied to the analysis of hot cracking on automatic tandem butt welding through the comparison with experimental results. As a result, it is demonstrated that the hot cracking can be evaluated by using the developed method.
Evaluation of Singular Value Decomposition (SVD) Enhanced Upscaling in Reservoir Simulation
Authors: Zhou Xu , Tyagi Mayank 
Published: December 2020

Abstract
Reservoir upscaling is an important step in reservoir modeling for converting highly detailed geological models to simulation grids. It substitutes a heterogeneous model that consists of high-resolution fine grid cells with a lower resolution reduced-dimension homogeneous model using averaging schemes. Its objective is to use a coarse grid model to represent a fine grid model, thus to reduce simulation time. The benefit of upscaling in reservoir simulation is that it efficiently saves simulation time, and effectively preserves key features of data for flow simulation.
Singular Vector Decomposition (SVD) is a matrix decomposition method. It has been used for image processing and compressing. It has been proved to be capable of providing a good compression ratio, and effectively saves digital image storage space. SVD also has been used in noise suppression and signal enhancement. It has been shown to be effective in reducing noise components arising from both the sound sampling and delivery system.
This study evaluates the effect of SVD in parameterization and upscaling for reservoir simulation. A two-phase flow reservoir model was created using data from the SPE tenth comparative solution project [1].
Simulation results show that SVD is valid in the parameterization of permeability values. The reconstructed permeability matrices using certain amount of singular values are good approximations of the original permeability values. Simulation results from SVD processed permeability values are similar to that using the original values.
SVD is then applied on the upscaled permeability value to evaluate the effectiveness on upscaling. Simulation results were compared between the base case, upscaled case, and SVD upscaled case. The simulation results did not show a significant improvement in the accuracy of predicting oil production by applying SVD on the upscaled permeability values. It could be because the reconstructed permeability matrix has the same dimension before and after the SVD processing, thus the model accuracy and efficiency are not significantly improved.
Future work includes adding more cases to further explore the effect of SVD on upscaling. The number of grid blocks may be increased, and more layers can be added to investigate whether SVD enhance upscaling for larger scale reservoir simulation models.
Comparative Study on Stress Intensity Factors for Surface Cracks in Welded Joint and Flat Plate by Using the Influence Function Method
Authors: Kyaw Phyo Myat , Naoki Osawa , Ramy Gadallah , Satoyuki Tanaka 
Published: December 2020

Abstract
Welding is an effective method for joining metallic structures which are very common in the construction of ships and offshore platforms. However, welded joints are prone to fatigue failure under cyclic loading due to the associated high residual stresses. In order to assess the fatigue crack propagation (FCP) accurately, precise evaluation of stress intensity factors (SIFs) is a key parameter. The residual stress distribution on the crack face of welded joints is usually non-uniform and also depends on boundary conditions. Therefore, an efficient technique is required to calculate SIFs for welded joints under non-uniform stress distribution.
In this study, SIFs of semi-circular surface cracked welded joints are calculated by using the influence function method (IFM). The IFM has been introduced as an efficient method to evaluate SIFs under arbitrary stress distribution. The influence coefficient databases (ICDB) are developed for welded joints and flat plate models using IFM in this study. As the crack face traction (CFT) integral is employed in this developed influence coefficients (IC), the SIFs given by IFM are more accurate compared to the previously established solutions without CFT-integral. The ICDB and SIFs evaluated by using welded joint and flat plate models are compared and discussed. This study reveals the difference between ICDB of flat plates and welded joints, and estimation error of calculated SIFs for welded joints by using flat plate ICDB.
A Novel Bi-Modal Wave Analysis Approach to Pipelay Installation Analysis
Authors: Lee Dan , Niesluchowski Piotr 
Published: December 2020

Abstract
The single wave or uni-modal wave analysis approach to define the installation seastates, based on a single wave with varying directions, wave heights and periods, is a standard approach among the installation contractors. However, in many of the offshore projects, e.g. offshore Trinidad, and Senegal and Mauritania, bi-modal seatates or waves are a common occurrence, but they are not considered in the installation analysis due to the complexity of the analysis and the computation time required to capture two waves, i.e. wind-sea and swell concurrently from different directions.
A novel bi-modal wave analysis approach is developed to assess the risk to pipelay installation operations due to the impact of bi-modal waves on the installation vessel, characterised by two peak frequencies of varying directions, wave heights and periods. The approach requires the use of clustered data, based on hindcast wave data over a period of time which can be provided by the Metocean Specialist. A combination of statistical evaluation of the clustered data and vessel response screening is used to identify critical clustered pairs for further installation analysis, and to complement the established single wave analysis and the associated installation seastates.
An example is provided in this paper to illustrate the benefits of bi-modal waves consideration, and to demonstrate the use of this novel approach in order to ensure any potential risk is captured so that the pipelay installation operations can be carried out in a safe offshore environment.
HSE Consequences of FPSO Mooring Lines Pretension Uncertainty in Deep Waters Applications
Authors: Araújo Jairo B. , Sales Joel S. , Fernandes Antonio C. , Thurler Ana C. S. 
Published: December 2020

Abstract
The purpose of FPSO (Floating Production Storage and Offloading) mooring system is to keep the unit operating in site in order to attend the Health, Safety and Environment (HSE) requirements and to meet the production risers design requirements. The pretension specification is a design task and it is a key activity due to its influence on extreme loads and fatigue life for both the mooring lines and risers. It is surprising that the project pretension specifications are not always actually implemented in practice and followed during all the unit life. Some inaccurate methods are used to get the actual pretension and may cause significant errors, and this may cause pretensions values outside design allowable tolerances.
A contemporary uncertainty analysis method that uses numerical simulations to estimate the consequences and propagation of the uncertainties in pretensions is applied. A case study is presented for the case of an operating FPSO moored by a spread system, offshore Brazil. A second investigation compares the uncertainty of pretensions measured by means of sensors with the uncertainties that arise from indirect measurements by top angles and as built data for mooring segments and anchor points.
The paper finally shows the need of a Mooring Integrity Management (MIM) implementation of at least annual pretension measurements with a robust and higher precision system.
Adjusting Environmental Contours for Specified Expected Number of Unwanted Events
Authors: Vanem Erik 
Published: December 2020

Abstract
Environmental contours are applied in probabilistic structural reliability analysis to identify extreme environmental conditions that may give rise to extreme loads and responses. Typically, they are constructed to correspond to a certain return period and a probability of exceedance with regards to the environmental conditions that can again be related to the probability of failure of a structure. Thus, they describe events with a certain probability of being exceeded one or more times during a certain time period, which can be found from a certain percentile of the underlying distribution. In this paper, various ways of adjusting such environmental contours to account for the expected number of exceedances within a certain time period are discussed. Depending on how such criteria are defined, one may get more lenient or more stringent criteria compared to the classical return period.
Ship Resistance When Operating in Floating Ice Floes: A Derivation of Empirical Equations
Authors: Huang Luofeng , Ryan Christopher , Igrec Bojan , Grech La Rosa Andrea , Stagonas Dimitris , Thomas Giles , Li Zhiyuan , Li Minghao , Ringsberg Jonas W. 
Published: December 2020

Abstract
With the effects of global warming, the Arctic is presenting a new environment where numerous ice floes are floating on the open sea surface. Whilst this has unprecedentedly improved Arctic shipping navigability and brought about significant opportunities, the interaction of such floes with ships has yet to be understood, thus hindering appropriate assessment of corresponding ship performance. This paper presents work on developing empirical equations to estimate the effects of such floes on ship resistance. Based on extensive data from validated computational simulations, the ice-floe resistance has been shown to correlate with ship beam, ship speed, ice concentration, ice thickness and floe diameter, and the regression powers of each the parameter on resistance are ascertained for a container ship. This leads to an empirical equation that can immediately predict ice-floe resistance in a given condition. The proposed approach has the potential to facilitate propulsion power estimates for Arctic shipping, as well as providing valuable insights into ship design for these environmental conditions.
Efficient Nonlinear Response Determination of an Array of OWC Energy Harvesters
Authors: Malara Giovanni , Spanos Pol D. 
Published: December 2020

Abstract
Oscillating Water Columns (OWC) are utilized for producing electrical energy from sea waves by exploiting the oscillation of a water column located under an air chamber for producing an air flow driving an air turbine connected to an electrical generator. The array configuration is considered in several engineering applications, where the OWCs are embedded in coastal infrastructures, such as vertical breakwaters. In this context, the water columns are likely to be placed nearby. Thus, interactions among chambers occur because of wave radiation phenomena.
This article describes a nonlinear model governing the dynamics of an OWC array embedded in a vertical breakwater. The differential equations include effects associated with hydrodynamic memory and isentropic thermodynamics, which prohibit the derivation of an exact solution giving the OWC array response. Thus, the article develops approximate solutions determined by relying on the concept of equivalent linearization, which is applied under the assumption of both deterministic, and stochastic excitations. Juxtaposition of the approximate approach results with relevant direct numerical integration data confirm its reliability and efficiency.
Collapse Pressure Enhancement of Offshore Pipeline Considering ERW Pipe Manufacturing Process
Authors: Han Seong-Wook , Park Yeun Chul , Kang Soo-Chang , Kim Ho-Kyung , Yi Jiwoon 
Published: December 2020

Abstract
As the application of electric resistance welded (ERW) pipes in deep-water increases, accurate structural performance assessment satisfying the limit state, which is collapse performance, is necessary. Advantages of ERW pipes are effective productivity coming from continuous manufacturing process, but it is hard to track change in mechanical properties during manufacturing. In this study, the ERW pipe manufacturing process was simulated as a three-dimensional finite element method, and the collapse analysis was performed by reflecting the results of the ERW pipe manufacturing process. The results showed that adjustment of ERW pipe manufacturing process had a significant effect on enhancement of collapse performance.
Development of Data-Driven Models for Prediction of Mooring Line Tensions
Authors: Kumar Nitesh , Liong Ching Theng , Chen Wei Kean , Magee Allan Ross , Chua Kie Hian , Choo Yoo Sang 
Published: December 2020

Abstract
This paper describes the development of data-driven models for the prediction of mooring line tensions by separating the low- and wave-frequency components of the tensions, such that the former is approximated as quasi-static tensions while the latter is predicted using ANN models.
A bilinear model is used to interpolate the low-frequency quasi-static tensions between known values in a look-up table while a feed forward neural network model that utilizes the fairlead motions as input is used to predict the tension dynamics at the fairlead. The ANN models are trained using the results from numerical simulations, such as those generated during the engineering design and construction stages of the floating structure.
The predicted line tensions are compared with those obtained using coupled numerical simulations, including test cases for different wave realizations that are not included in the training dataset. Models trained for single and multiple directions of the environment are also assessed for prediction accuracy.
Initial comparisons show that good predictions of line tensions can be obtained for certain environments using the proposed approach, thus demonstrating the potential for use in applications where real-time predictions are required to enhance the safety and / or reliability of mooring systems.
Off-Bottom Plug Placement: How It Works?
Authors: Ghazal Abdallah , Karimfazli Ida 
Published: December 2020

Abstract
In Canada, the Alberta Energy Regulator’s (AER) liability report, issued in 2018, predicted that the number of inactive wells in the province will double by 2030. Despite the increase in the number of inactive wells, there is a need to close them properly to avoid hazards escape. Various aspects of well plug technologies in the Canadian abandoning industry are empirical. Many plugs are formed by injecting cement slurry into wells that are otherwise filled with fresh water for the slurry to build up on top of a water layer at a desired location. However, cement is heavier than water. Thus, successful plug placement following this methodology is questionable from the hydrodynamics perspective.
The present study aims to identify features of successful processes for placement of off-bottom plugs. To that end, we investigate mixing of fluids of different densities as the denser fluid is injected into the lighter fluid. Cement slurry is modeled as a viscoplastic fluid. The fluid motion is governed by hydrodynamic models, and the two fluids (i.e. cement and water) are considered to be miscible and are allowed to mix. Systematic numerical simulations aim to reveal how the characteristics of cement and the well configuration affect the placement process.
We show that successful plug placement depends on the formation of a mixed layer, of the wellbore fluid and cement slurry, below the injection site. We identify and provide representative cases of the processes promoting the formation of the mixed layer: high diffusion and growing instabilities.
Acoustic Study of Wave-Breaking to Enhance the Understanding of Wave Physics
Authors: Odzer Michael , Francke Kristina 
Published: December 2020

Abstract
The sound of waves breaking on shore, or against an obstruction or jetty, is an immediately recognizable sound pattern which could potentially be employed by a sensor system to identify obstructions. If frequency patterns produced by breaking waves can be reproduced and mapped in a laboratory setting, a foundational understanding of the physics behind this process could be established, which could then be employed in sensor development for navigation.
This study explores whether wave-breaking frequencies correlate with the physics behind the collapsing of the wave, and whether frequencies of breaking waves recorded in a laboratory tank will follow the same pattern as frequencies produced by ocean waves breaking on a beach.
An artificial “beach” was engineered to replicate breaking waves inside a laboratory wave tank. Video and audio recordings of waves breaking in the tank were obtained, and audio of ocean waves breaking on the shoreline was recorded. The audio data was analysed in frequency charts. The video data was evaluated to correlate bubble sizes to frequencies produced by the waves.
The results supported the hypothesis that frequencies produced by breaking waves in the wave tank followed the same pattern as those produced by ocean waves. Analysis utilizing a solution to the Rayleigh-Plesset equation showed that the bubble sizes produced by breaking waves were inversely related to the pattern of frequencies. This pattern can be reproduced in a controlled laboratory environment and extrapolated for use in developing navigational sensors for potential applications in marine navigation such as for use with autonomous ocean vehicles.