bluuebunny/crossref_metadata_2025_split huggingface dataset:
Viscosity Models for Drilling Fluids: Viscosity Parameters and Their Use
Authors: Saasen Arild , Ytrehus Jan David 
Published: November 2019

Abstract
The most common viscosity models used in the drilling industry are the Bingham, the Power-Law and the Herschel-Bulkley models. The scope of the present paper is to outline how to select the individual models, and how the models need to be re-formulated to be able to have parameters with a physical meaning.
In principle, the Bingham model itself have physical parameters being the yield point and the plastic viscosity. However, the Bingham model very often only very poorly describe the viscosity in complex fluids. This yield stress can be described within a reasonable accuracy by application of the low-shear yield point. A similar problem exists with the Power-Law model resulting from the model’s absence of a yield stress. The compromise model is the Herschel-Bulkley model which contains a yield stress and a power-law term. This model describes the drilling fluid viscosity with reasonable accuracy and includes both the Bingham and Power-Law models as limit formulations.
It is not possible to select fluids based on the Herschel-Bulkley traditional parameters alone. The reason is that the Herschel-Bulkley power-law term’s viscosity parameter has a unit dependent on its power-law exponent. In the present approach the fluid is described using a yield stress, a surplus stress at a characteristic shear rate of the fluid flow and finally a power-law exponent making the fluid applicable in the practical shear rate ranges. The surplus stress is no-longer dependent on other parameters. Hence, we have re-arranged the viscosity model to have independent measurable quantities.
Extended Kalman Filtering for Estimating Drag and Inertia Coefficients for Slender Offshore Structures
Authors: Bhagtani Dhruv , Saha Nilanjan 
Published: November 2019

Abstract
System identification is used in location detection, target tracking, prediction in oil markets and so on. In this paper, the Kalman Filter (extended) technique is explored in monitoring the health of a jacket structure, in a stochastic excited wave environment. Hydrodynamic coefficients drag (CD) and inertia (CM), usually experimentally obtained, are important parameters to assess the force on a structure using the Morison’s equation. Usually these coefficients appearing in the force equation are un-known for majority of the slender offshore structures and are a priori obtained using some set of prototype experiments as these parameters depend on lot of factors (Keulegan-Carpenter number, roughness, dimensions and so on). Therefore, the recourse to parameter identification techniques based on Kalman filtering can be an alternative.
In this paper, the problem is analysed using Airy wave theory where a cylinder is assumed to be fixed at the seabed. Numerical analysis is done to create experimental conditions to observe the dynamic response of the system. These numerical results are then plagued with white noise to represent the observations from experiments. These measurements are subsequently used in identification of the drag and inertia coefficients for the cylinder. This is presently attempted using the Extended Kalman Filter technique.
With the use of this model the Extended Kalman Filter is shown to be able to identify time varying drag and inertia coefficients of the cylinder problem. For the present case, measurement sensors are placed for the measured force, along with the motions: velocity and acceleration. The above method can easily be implemented in jacket structures or similar offshore structures for attention due to increase in forces owing to marine growth.
Effect of LCM Fibers on the Rate of THF-Water Clathrate Hydrate Growth in Water-Based Drilling Fluids
Authors: Nielsen James L. , Nahri Syed Y. , Zhao Wei , Wei Panfeng , Chen Yuanhang 
Published: November 2019

Abstract
This study investigates how different sized fibers used commonly as Lost Circulation Material (LCM) change the time required for induction and agglomeration of natural gas hydrates in drilling fluids using laboratory experimentally obtained data. Three different sizes of LCM fibers, fine, medium and coarse, were studied to observe how the size of each type of fiber affects the rate of hydrates growth. THF-Water clathrate hydrates were used as a model for hydrate growth at standard pressure conditions using a 20:80 molar ratio of THF to water. The concentrations of LCM fibers tested varied between 1–3% by weight. Each type of fiber was tested individually at −6 °C, −3 °C, and 0 °C and monitored for changes in hydrate induction and agglomeration rates. Tests were repeated using water-based drilling fluids using bentonite as the primary viscosifier and barite as a weighting agent to test 10, 12, and 14 ppg fluids. Fibers were tested under static conditions to identify changes in the nucleation and agglomeration rates for each. The rates of hydrate nucleation between samples of THF-Water and LCM fibers and each sample of water-based drilling fluid with LCM fibers was found to be consistent with no statistically significant change in rate being observed due to the fibers present. However, we observed a significant change in the rate of agglomeration that was dependent on the size and concentration of the fiber particles. We identified that fine fibers provided the most significant increase in the rate of agglomeration followed by medium and coarse fibers, respectively, with increasing LCM fiber concentrations. Compared to control samples, using fibers produced initial hydrate agglomeration around the freely suspended fibers. Due to their proximity to other fibers with hydrates developing around them, the hydrates were able to form very large free moving crystals in the solution before completely agglomerating and forming a solid plug. The results and conclusions provide new insights and guidance in drilling fluids and LCM design for offshore deep-water drilling. Gas hydrates can potentially develop and agglomerate along in the BOP and kill/choke lines during a well control event, as what is suspected as what happened in Macondo blowout where a considerable amount LCMs were used during drilling and as a spacer during a negative pressure test.
Cone Penetration Test in Stiff Over Soft Clay in Centrifuge Test
Authors: Xie Qiang , Hu Yuxia , Cassidy Mark , Salehi Alireza 
Published: November 2019

Abstract
This paper describes a numerical study on soil characterization of stiff over soft clays in centrifuge test using cone penetration test (CPT), especially when the top stiff layer is thin relative to the centrifuge cone size. An extensive parametric study was conducted using large deformation finite element (LDFE) analysis, with the cone penetrating continuously from the soil surface. The LDFE model has been validated against existing physical test data with very good agreement. Since the bottom soft clay was normally thick enough to fully mobilise the ultimate cone resistance, its undrained shear strength can be interpreted by the existing approach for cone deep penetration in a uniform clay layer. Thus, the challenge was to interpret the strength of the top stiff layer, where the layer thickness was not thick enough to fully mobilise its ultimate resistance. Both top layer thickness ratios (to the cone diameter) and layer strength ratios were considered in the parametric study. Based on the results from LDFE analyses, the interpretation formula of the undrained shear strength in the top stiff layer was proposed as a set of new bearing factors. The proposed cone bearing factor was a function of the ratio of the measured peak cone resistance in the top layer to the stable/ultimate cone resistance in the bottom layer and the ratio between the top layer thickness to the cone diameter. The formula can be used directly when the top layer thickness was known based on the sample preparation. However, the layer interface can be identified based on the study here, if the top layer thickness was not certain. A design flow chart was provided for interpretations of top clay layer strength and top layer thickness based on the cone resistance profile obtained from CPT test.
On Design and Analysis of a Drivetrain Test Rig for Wind Turbine Health Monitoring
Authors: Balestra Lorenzo , Nejad Amir R. , Naldi Giovanni 
Published: November 2019

Abstract
The reliability of offshore wind turbines is a key factor when estimating maintanence costs, downtime due to component failure and overall efficiency during operational life. Offshore wind turbines have limited accessibility and operate in harsh environments and, as a result, it is difficult to perform frequent checks on electrical and mechanical component. Drivetrain test rigs (DTR) are crucial to the task of: validating the design of new components to avoid early life failure, observe the behaviour of components under load over long periods of time in a controlled environment and produce a maintanence plan that minimize costs and frequency of intervention.
In this paper, after a brief introduction on the state of the art in DTR technology, is described a methodology that can be used to create an effective conceptual design for a drivetrain test rig, focusing also on the possible downscaling.
The paper starts by analyzing the benefits of the drivetrain use in the wind power industry, bringing examples of real test rigs used in industrial and academical world. Once the topic is mastered it is possible to proceed with a description of the various phases needed to obtain the conceptual design, from the definition of layout to the preliminary 3D modeling.
The test rig that is here designed, while inspired from full scale dynamometers used in the industry, is thought as a laboratory tool for academical use that can be used by students to investigate fault detection methods and health monitoring systems of wind turbines. It is also included a section dedicated to the possible techniques for downscaling the test rig, based on simple considerations of the drivetrain mechanical behaviour. Downscaling becomes a key factor when facing the need to test turbine components of ever increasing dimensions in laboratories with limited space and budget. The definition of a procedure to create a scaled version will allow laboratories to build test rigs of smaller dimension but with a damage model for the various components still closely linked to the one in real scale. Downscaling is also a necessity when working with limited power sources, not able to recreate the conditions that the real scale turbine encounters.
The ultimate goal is to define a solid base to allow further development in the detailed design phase.
Time-Domain Diffraction Modelling With Mean Force Effects and Experimental Comparison for Slack-Moored M4 Wave Energy Converter
Authors: Stansby P. K. , Carpintero Moreno E. 
Published: November 2019

Abstract
Linear diffraction modelling of irregular wave structure interaction is standard practice in both the frequency and time domains for fixed and floating bodies. This has been extended for the modular wave energy converter M4 with multiple floats and power take offs. In the time domain second-order forces assuming a stationary body have been added for floating wind energy platforms. This misses second-order, including mean, effects due to radiation damping, drag forces and the mechanical damping of wave energy conversion. If these are linearized they may be included in a frequency domain analysis. However mechanical damping and mooring forces on slack-moored platforms are generally highly nonlinear and time domain analysis is required. In this paper response is first computed with linear analysis and mechanical damping which has been shown to give reasonable prediction of experimental measurement for the response and power output of M4. The response gives the absorbed energy flux due to mechanical and radiation damping which is converted into a mean force through an average wave celerity. The model is extended to include a mooring and these mean forces; the computation is then repeated. The mean forces have negligible effect on response and associated power take off but determine the mooring forces. For a slack mooring zero stiffness is assumed. Comparing with wave basin experiments for the 6-float M4 configuration in operational conditions, mean mooring forces are generally underestimated, markedly for larger periods.
Analysis on Hydrodynamic Responses of a Spar Offshore Wind Turbine With an Innovative Type of Mooring System
Authors: Ma Yuan , Chen Chaohe , Yan Xinkuan , Shen Yijun , Fan Tianhui 
Published: November 2019

Abstract
The mooring system is a key component connecting a floating offshore wind turbine (FOWT) to the seabed. Generally, the traditional mooring systems mainly control the horizontal motions of the floating platform. However, due to the existence of blades, tower structure and the requirement of power generation efficiency, there is a high requirement on the pitching performance when a platform is used for the floating wind turbine. Therefore, an innovative type of mooring system which could improve the pitch performance of the FOWT is really needed.
In this paper, considering the OC3-Hywind Spar floating wind turbine, based on the original type of 3 × 3 mooring system, an innovative type of mooring system which has a better control performance of the pitch of FOWT is designed. Then, the hydrodynamic responses of the floating wind turbine platform are investigated. The influence of two different mooring system types on the hydrodynamic responses of the FOWT are compared and analyzed. The conclusions of this study could serve as a reference for the mooring system design of floating wind turbine systems.
Extreme Response Analysis of an End-Anchored Floating Bridge
Authors: Cheng Zhengshun , Gao Zhen , Moan Torgeir 
Published: November 2019

Abstract
During the design of a floating bridge, extreme structural responses are required to be properly evaluated for ultimate limit state (ULS) design check. This study addresses the estimation of extreme structural responses for an end-anchored curved floating bridge. The floating bridge, about 4600 m, consists of a cable-stayed high bridge part and a pontoon-supported low bridge part. The long-term extreme responses are approximated by using a engineering approach, i.e., the environmental contour method. The sea state with 100-year environmental conditions is considered, and a 90% fractile is used to calculate the short-term extreme responses by using the Gumbel method and the mean up-crossing rate (MUR) method based on 100 1-hour simulations with different seeds.
The extreme responses are expressed as μ + κσ, where μ and σ are the ensemble mean and standard deviation, and κ is a multiplying factor. Numerical results show that structural responses are close to Gaussian distributed. κ of axial force and strong axis bending moment along the bridge girder estimated by both the Gumbel and MUR methods vary in the vicinity of 4. κ estimated by the two method deviates, especially for axial force. Moreover, for both methods the estimated κ deviates more significantly if fewer ensembles are used.
Experimental Study on Hydrodynamic Performance of Mini-AUV in Non-Uniform Flow Field
Authors: Zhuang Jiayuan , Cao Jian , Su Yumin , Zhang Lei , Yu Xianzhao 
Published: November 2019

Abstract
Experimental investigations of hydrodynamic performance of mini-AUV in non-uniform flow field were conducted in the basin of Harbin Engineering University, the revolved body and flat body of mini-AUV model were tested respectively. The three dimensional flow fields were generated by local jet of the underwater pump, and circulated in the basin. The three dimensional velocity distributions at different positions were measured by a Doppler current profiler. The three component balance was used to measure the drag, lateral force and yawing moment acting on the mini-AUV models depending on drift angle in the flow field, and the influence of complex flow field to the hydrodynamic performance of mini-AUV indicated that drag was not sensitive to drift angle and yawing moment was increased obviously. The conducted experiments could supply reference to the maneuverability research of mini-AUV in real marine environments in the future.
Optimization of Valves Packings Through Characterization and Calculation
Authors: Lejeune Hubert , Joulain Frédéric 
Published: November 2019

Abstract
In the valve industry, there is combined demand from the end-users for fugitive emissions reduction and energy efficiency improvement through the reduction of stem/packing friction forces. These two different goals will involve opposite trends on the load to be applied on the packing i.e. high load for good tightness and low load for low friction. Thus, the ability to define optimal ranges of packing tightening is important. Nevertheless, no standardized method for packing calculation nor packing full characterization (mechanical, friction, sealing performance vs. packing load,..) exists in Europe, as for bolted flange joints and associated gasket with EN1591-1 [1] and EN13555 [2].
In collaboration with ESA (European Sealing Association, www.europeansealing.com) and FSA (Fluid Sealing Association, www.fluidsealing.com), the Fluid Equipment Committee of CETIM has developed a tool for the optimization of packing. A set of tests enables to get the packing characteristics needed for the calculation. These tests can also be used for the comparison of packing materials and/or installation procedures performances in defined test conditions.
This paper details the proposed calculation method and describes the associated test rigs and procedures. First test results and a calculation example are also given to show how the method works.
Resource Allocation Model Toward Seismic Water Pipeline Risk Mitigation Measures
Authors: Peyghaleh Elnaz , Alkhrdaji Tarek 
Published: November 2019

Abstract
History of earthquake’s damages have illustrated the high vulnerability and risks associated with failure of water transfer and distribution systems. Adequate mitigation plans to reduce such seismic risks are required for sustainable development. The first step in developing a mitigation plan is prioritizing the limited available budget to address the most critical mitigation measures. This paper presents an optimization model that can be utilized for financial resource allocation towards earthquake risk mitigation measures for water pipelines. It presents a framework that can be used by decision-makers (authorities, stockholders, owners and contractors) to structure budget allocation strategy for seismic risk mitigation measures such as repair, retrofit, and/or replacement of steel and concrete pipelines. A stochastic model is presented to establish optimal mitigation measures based on minimizing repair and retrofit costs, post-earthquake replacement costs, and especially earthquake-induced large losses. To consider the earthquake induced loss on pipelines, the indirect loss due to water shortage and business interruption in the industries which needs water is also considered. The model is applied to a pilot area to demonstrate the practical application aspects of the proposed model. Pipeline exposure database, built environment occupancy type, pipeline vulnerability functions, and regional seismic hazard characteristics are used to calculate a probabilistic seismic risk for the pilot area. The Global Earthquake Model’s (GEM) OpenQuake software is used to run various seismic risk analysis. Event-based seismic hazard and risk analyses are used to develop the hazard curves and maps in terms of peak ground velocity (PGV) for the study area. The results of this study show the variation of seismic losses and mitigation costs for pipelines located within the study area based on their location and the types of repair. Performing seismic risk analysis analyses using the proposed model provides a valuable tool for determining the risk associated with a network of pipelines in a region, and the costs of repair based on acceptable risk level. It can be used for decision making and to establish type and budgets for most critical repairs for a specific region.
Comparison of EN 13555 Gasket Test Data With Predicted Leak Rates Derived From Draft PVRC Equations
Authors: Rice Dale A. , Waterland Jerry 
Published: November 2019

Abstract
In flanged connections, all gaskets have some level of fluid leakage, depending on gasket type and other factors. Using published Room Temperature Tightness (ROTT) test data and draft PVRC (Pressure Vessel Research Council) equations, a simple model to calculate the predicted tightness / leak rates of various gasket materials has been previously documented. The model assumes a set of draft empirical equations previously published by ASME / PVRC but with an incorporated stress loss factor. Tightness at flange assembly as well as following unloading can be estimated with the model. The EN 13555 test standard includes measuring the test gas leak rates for a series of gasket stresses but at a single operating pressure for each test. Correlation of EN 13555 data with PVRC model predicted leak rates over a range of manufactured gasket materials is demonstrated. The leak rate data for specific gasket materials have been found to compare favorably with the leak rates at assembly as determined in using the PVRC model. The application and corresponding limitations of certain EN 13555 gasket parameters are discussed. The end user may wish to consider the use of the PVRC empirical approach to estimate predicted long-term leak rates of competing gasket materials as a key factor in the gasket selection process.
Variable Inertia Damper Using a Flywheel Filled by MR Fluid
Authors: Matsuoka Taichi 
Published: November 2019

Abstract
To get a variable inertia effect for vibration reduction, a semiactive damper using a flywheel filled by MR fluid was developed. The damper comprises a ball screw mechanism and the flywheel, which is able to change a moment of inertia. MR fluid is filled into the flywheel. Particles are clustered at outer circumference edge inside the wheel when the magnetic field is applied to the wheel edge, so the moment of inertia on the flywheel can be changed artificially. The prototype device was manufactured, and the dynamic performance was investigated. Finally the changeable inertia effect was confirmed experimentally.
Using Additive Manufacturing for Making Light Water Reactor Components
Authors: Rebak Raul B. , Lou Xiaoyuan 
Published: November 2019

Abstract
Making light water reactor (LWR) components using additive manufacturing (AM) provides a high degree of design freedom to create complex near net shape geometries, with significant reduction in the deployment time. Since most of the current AM research focus on the refining of the fabrication variables, little information exists on the actual corrosion behavior (including general corrosion, localized corrosion and environmentally assisted cracking - EAC) of AM components. The most frequent operational material failure modes in LWR is EAC and debris fretting of fuel rods, therefore the objective of this work was to evaluate the environmental performance of AM type 316L SS in relation to the traditionally melted and forged wrought material. Stress corrosion cracking results show similar behavior between AM and wrought 316L SS in high temperature water. Ambient temperature electrochemical testing showed that the AM 316L SS was slightly more resistant to localized corrosion than the traditional wrought material and that AM material did not suffer sensitization during fabrication or heat treatment processes.