bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of the internal syringe shape on the International Dysphagia Diet Standardization Initiative flow test
Authors: Nanto Tomoki , Nakao Yuta , Kodama Norihiko , Uchiyama Yuki , Fong Raymond , Domen Kazuhisa
Published: October 2021

The International Dysphagia Diet Standardization Initiative (IDDSI) proposed the flow test (FT) as a simple method for measuring the viscosity of thickened liquids. However, the FT specifies the use of a particular syringe type (BD‐Slip), which is unfortunately not easily available in Japan. Therefore, the current study primarily aimed to investigate the effects of the internal syringe shape on IDDSI FT and identify the most suitable syringe available in Japan for xanthan gum‐based thickened liquids. Accordingly, four syringes, namely, Luer slip tip, Luer‐Lok tip, TERUMO, and NIPRO syringes, were used to examine FT value with water and nine different water viscosity levels. The correlation and systematic errors on residual FT values between the BD‐Slip syringe and the other three syringes were analyzed. The two‐dimensional internal shapes of the four syringes were measured using industrial computed tomography (CT) scanning. Based on the results of our FT, TERUMO had the smallest error range among the three syringes, without systematic errors. On a CT scan, three of five tip‐shape parameters showed the smallest difference between BD‐Slip and TERUMO syringe. Therefore, TERUMO had the smallest FT error range compared with that in BD‐Slip tip syringe, indicating that TERUMO could be used as a substitute for BD‐Slip when performing IDDSI FT with xanthan gum‐based thickened water in Japan.
The Importance of Nutrition Education in Achieving Food Security and Adequate Nutrition of the Poor: Experimental Evidence from Bangladesh*
Authors: Tauseef Salauddin
Published: October 2021

Nutrition‐sensitive social protection that enhances household resources and nutrition knowledge can be an important avenue of addressing food security and nutrition concerns of the poor. This paper studies the impact of a cluster randomized intervention of cash or food transfers, with‐or‐without nutrition behavioural change communication (BCC), on food security and nutrition outcomes in rural Bangladesh. We find that the addition of the BCC to transfers led to the greatest impact on the quantity and quality of food consumed by household members, especially women and children. The addition of BCC also had the greatest impact in reducing the incidence and intensity of deprivations measured using a nutrition‐sensitive multidimensional poverty index. Evidence suggests this occurs through the BCC inducing increased consumption of flesh food, egg, dairy, fruits and vegetables and through investments in housing, sanitation and assets.
Identifying multiple knee pain trajectories and the prediction of opioid and NSAID medication used: A latent class growth approach
Authors: Haybatollahi Sayyed M. , James Richard J. E. , Fernandes Gwen , Valdes Ana , Doherty Michael , Zhang Weiya , Walsh David A. , Ferguson Eamonn
Published: October 2021

Background

Knee pain is a major source of distress and disability, with pain progression highly variable between individuals. Previous studies defining pain trajectories have all used a single measure of pain, and these differ across studies. Different measures reflect diverse pain mechanisms. To ascertain the clinical utility of pain trajectories, we explored associations between opioid and non‐steroidal anti‐inflammatory drug (NSAID) use.

Methods

We model pain trajectories using two measures—Intermittent and Constant Osteoarthritis Pain (ICOAP) and the painDETECT, in 2141 participants, across 3 waves (the baseline, 1‐ and 3‐year assessments) of the Knee Pain In the Community (KPIC) cohort.

Results

Latent class growth analysis identified six trajectories using ICOAP subscales (High‐Stable, Low‐Stable, Moderate Worsening, Moderate Recovering, Worsening, and Recovering) and four trajectories using painDETECT (High‐stable, Low‐stable, Moderate Worsening, and Moderate Recovering). There was a high degree of correspondence between people assigned to pain trajectories between ICOAP intermittent and constant subscales, but less so using painDETECT. Opioid use was associated with ICOAP trajectories only (e.g., High‐Stable and Worsening intermittent ICOAP trajectories) and in women.

Conclusion

Different measures of pain produce different patterns of pain progression and these are differentially related to medication use. Opioid use is linked to trajectories of pain based on the impact of pain on behavior and not pain symptoms. Thus, managing pain's behavioral impact is more central to understanding opioid use than managing pain symptoms. These findings support more in‐depth questioning about the type of pain and its progression in clinical practice.
Bread and Social Justice: Measurement of Social Welfare and Inequality Using Anthropometrics
Authors: Abu‐Zaineh Mohammad , Abul Naga Ramses H.
Published: October 2021

We address the question of the measurement of health achievement and inequality in the context of variables exhibiting an inverted‐U relation with health and well‐being. The chosen approach is to measure separately achievement and inequality in the health increasing range of the variable, from a lower survival bound a to an optimum value m, and in the health decreasing range from m to an upper survival bound b. Because in the health decreasing range, the equally distributed equivalent value associated with a distribution is decreasing in progressive transfers, the paper introduces appropriate relative and absolute achievement and inequality indices to be used for variables exhibiting a negative association with well‐being. We then discuss questions pertaining to consistent measurement across health attainments and shortfalls, as well as the ordering of distributions exhibiting an inverted‐U relation with well‐being. An illustration of the methodology is provided using a group of five Arab countries.
Good intentions in complex realities: Challenges for designing responsibly in digital agriculture in low‐income countries
Authors: McCampbell Mariette , Schumann Charlotte , Klerkx Laurens
Published: October 2021

Human‐centred design (HCD) approaches are adopted to develop digital agriculture interventions inclusively and responsibly. Whether these approaches indeed lead to responsible designs remains unclear, especially for low‐income countries. Using a Rwandan case‐study, we contribute to debates on inclusive, participatory and responsible design by developing a framework for operationalising HCD and responsible innovation in practice and studying the process of designing a digital agriculture intervention for banana disease management. The four dimensions (inclusion, anticipation, reflexivity, responsiveness) of responsible innovation and our own framework of digital rights served as analytical lenses. Findings show that power relations and digital capacity negatively affect user inclusivity in design. The context in which HCD is deployed hinders anticipation, reflexivity and responsiveness, resulting in design decisions that do not fully respect digital rights and thus in potentially irresponsible digital technologies. Broader, long‐term consequences of digital technologies should be a central consideration in design processes, while responsible innovation theory needs to become cognizant of the complex realities in which digital innovations emerge.
Experimental investigation on the concrete fracture process zone using electronic speckle pattern interferometry
Authors: Huang Xingzhen , Chen Hongniao , Sun Bin
Published: October 2021

In order to advance the understanding of fracture failure mechanisms in concrete, a series of three‐point bend tests of pre‐notched specimens were conducted to study the characteristics of the fracture process zone. Electronic speckle pattern interferometry (ESPI) was used to determine the location and size of the cracks. The experimental results have shown that crack in the pre‐notched concrete beams will initiate when the load increases to 40% of the peak load (Pmax) and expands unstably after reaching the peak load. When the load drops to about 25% Pmax in the load drop section, a complete fracture process zone (FPZ) was developed, and the corresponding crack tip opening displacement is about 7.1 times to the critical crack tip opening displacement. The analysis of surface strain of concrete specimen showed that microcracks will initiate when the surface tensile strain of concrete reaches about 2 × 10−4; when the surface tensile strain value of concrete reaches 4 × 10−2, the FPZ will move forward; the length of the FPZ of concrete essentially remains the same in the entire fracture process, which is about 71% of the ligament height. The analysis of experimental data also shows that the size of the FPZ is not significantly affected by the cubic compressive strength of concrete. In addition, the tension‐softening curves of the specimens were finally determined by using the incremental displacement collocation method, and it is concluded that the critical width of the FPZ is related to the cubic compressive strength of the concrete.
Trends in hepatitis E virus infection: Analyses of the long‐term screening of blood donors in Hokkaido, Japan, 2005–2019
Authors: Sakata Hidekatsu , Matsubayashi Keiji , Iida Juri , Nakauchi Kenta , Kishimoto Shinichi , Sato Shinichiro , Ikuta Katsuya , Satake Masahiro , Kino Shuichi
Published: October 2021

Background

After experiencing several cases of transfusion‐transmitted hepatitis E (TT‐HE) in Hokkaido, Northern Japan, hepatitis E virus (HEV) screening in blood donors, using a nucleic acid amplification test (NAT), was introduced in 2005.

Study Design and Methods

The frequency of HEV RNA‐positive donations (2005–2019) was investigated, and the HEV RNA‐positive specimens were phylogenetically analyzed. In August 2014, the 20‐pooled NAT (20P‐NAT) was replaced with an individual‐NAT (ID‐NAT) system.

Results

Until 2019, the frequency of HEV RNA‐positive donors was 0.011% (289/2,638,685) with 20P‐NAT and 0.043% (597/1,379,750) with ID‐NAT, and no TT‐HE cases were observed in Hokkaido. The prevalence among male, but not female donors, increased significantly between 2015 and 2019. Eighty‐nine percent of HEV isolates from donors were genotype 3 and the remainder were genotype 4, and many clusters existed in each genotype. ALT levels at the time of donation were significantly higher in donors with genotype 4. Four subgenotypes, namely 3a (37%), 3b (41%), 3e (6%), and 4c (10%), comprised 94% of the total. During this period, the most identified subgenotype, 3a, transitioned to 3b. Majority of the HEV strains within the same clusters were detected in the same geographical region around the same period. Many of the human HEV isolates were shown to coexist closely with animal HEV isolates phylogenetically.

Conclusion

In Hokkaido, multiple divergent HEV strains have been circulating, and small outbreaks of hepatitis E have occurred in the last 15 years. The results suggested that HEV NAT can contribute significantly in ensuring safety during blood transfusions.
Effect of Phase Change Material on Dynamic Thermal Management Performance for Power Electronics Packages
Authors: Hollis Justin , Sharar Darin J. , Bandhauer Todd
Published: October 2021

High-temperature silicon carbide (SiC) die are the most critical and expensive component in electric vehicle (EV) power electronics (PE) packages and require both active and passive methods to dissipate heat during transient operation. The use of phase change materials (PCMs) to control the peak junction temperature of the SiC die and to buffer the temperature fluctuations in the package during simulated operation is modeled here. The latent heat storage potential of multiple PCM and PCM composites is explored in both single-sided and dual-sided package configurations. The results of this study show that the addition of PCM into two different styles of PE packages is an effective method for controlling the transient junction temperatures experienced during two different drive cycles. The addition of PCM in a single-sided package also serves to decrease temperature fluctuations experienced and may be used to reduce the necessary number of SiC die required for EVs, lowering the overall material cost and volume of the package by over 50%. PCM in a single-sided package may be nearly as effective as the double-sided cooling approach of a dual-sided package in the reduction of both peak junction temperature of SiC as well as controlling temperature variations between package layers.
Efficient Three-Dimensional Model to Predict Time History of Structural Dynamics in Cold Rolling Mills
Authors: Patel Akash , Malik Arif , Mathews Ritin
Published: October 2021

Introduced is a new physics-based three-dimensional (3D) mathematical model capable of efficiently predicting time histories of the nonlinear structural dynamics in cold rolling mills used to manufacture metal strips and sheets. The described model allows for the prediction of transient strip thickness profiles, contact force distributions, and roll-stack deformations due to dynamic disturbances. Formulation of the new 3D model is achieved through a combination of the highly efficient simplified-mixed finite element method with a Newmark-beta direct time integration approach to solve the system of differential equations that governs the motion of the roll-stack. In contrast to prior approaches to predict structural dynamics in cold rolling, the presented method abandons several simplifying assumptions and restrictions, including 1D or 2D linear lumped parameter analyses, vertical symmetry, continuous and constant contact between the rolls and strip, as well as the inability to model cluster-type mill configurations and accommodate typical profile/flatness control mechanisms used in industry. Following spatial and temporal convergence studies of the undamped step response, and validation of the damped step response, the new model is demonstrated for a 4-high mill equipped with both work-roll bending and work-roll crown, a 6-high mill with continuously variable crown (CVC) intermediate rolls, and finally a complex 20-high cluster mill. Solution times on a single computing processor for the damped 4-high and 20-high case studies are just 0.37 s and 3.38 s per time-step, respectively.
The Effect of Carbon Fiber Types on Tool Wear During Edge Trimming of 0 deg, 45 deg, 90 deg, and 135 deg Carbon Fiber-Reinforced Plastic Laminates
Authors: Khawarizmi Ryan , Bin Abdullah Mohammad Sayem , Han Yinyin , Kim Dave , Kwon Patrick
Published: October 2021

Carbon fiber-reinforced plastics (CFRP) composites are difficult-to-machine materials due to extensive tool wear. This article investigates the impact of carbon fiber types on tool wear in edge-trimming CFRPs, each with the ply angle of 0 deg, 45 deg, 90 deg, or 135 deg, using uncoated tungsten carbide endmills at the high spindle speed of 6000 rpm and the constant feed of 0.0508 mm/rev. Three distinct types of carbon fiber tows, including T300 as standard modulus (SM), IM-7 as intermediate modulus (IM), and K13312 as high modulus (HM), have been vacuum infused into CFRP laminates and edge trimmed to investigate wear characteristics. Three wear criteria measured are flank wear, edge rounding radii, and worn area. The results show that tool wear is influenced by carbon fiber properties, such as fiber tensile strength, tensile modulus, and fiber microstructure. Overall, IM carbon fibers with the highest tensile strength produced the most extensive tool wear due to the abrasive carbon fibers. Of four fiber directions, the largest tool wear was obtained from the 45 deg angle, while the lowest tool wear occurred in the 0 deg angle.
Dimensionality Reduction of High-Fidelity Machine Tool Models by Using Global Sensitivity Analysis
Authors: Ellinger Johannes , Semm Thomas , Zaeh Michael F.
Published: October 2021

Models that are able to accurately predict the dynamic behavior of machine tools are crucial for a variety of applications ranging from machine tool design to process simulations. However, with increasing accuracy, the models tend to become increasingly complex, which can cause problems identifying the unknown parameters which the models are based on. In this paper, a method is presented that shows how parameter identification can be eased by systematically reducing the dimensionality of a given dynamic machine tool model. The approach presented is based on ranking the model’s input parameters by means of a global sensitivity analysis (GSA). It is shown that the number of parameters, which need to be identified, can be drastically reduced with only limited impact on the model’s fidelity. This is validated by means of model evaluation criteria and frequency response functions which show a mean conformity of 98.9% with the full-scale reference model. The paper is concluded by a short demonstration on how to use the results from the GSA for parameter identification.
Experimental Study on Structural Rehabilitation of Severely Damaged I-Beams Using Fibre Reinforced Polymers
Authors: George Jerin Mathew , Kimiaei Mehrdad , Elchalakani Mohamed
Published: October 2021

Fixed and Floating Offshore structures commonly utilize I-beams as structural components withstanding distributed loads on their decks or inside hulls. These structural members get damaged due to the corrosive marine environment leading to a condition in which they need replacement or rehabilitation. Such situations are not desirable as it will incur monetary losses directly with replacement or repair costs and indirectly through operational losses due to shut down for hot repair works. A safe and economical alternative for structural rehabilitation of damaged I-beams is using Fibre Reinforced Polymer (FRP) composites. An experimental investigation on the feasibility of repair of a heavily damaged I-beam using two different types of FRPs is presented. The severe damage in the I-beam was artificially introduced by removing both flanges and the web for 300 mm in the mid-span of 1800 mm long I-beam. Four-point bending tests under static loads were performed until failure of the beam. The first repair was done using carbon fibre reinforced polymers (CFRPs) and the second one utilized glass fibre reinforced polymers (GFRP). The CFRP repaired specimen showed 277% improvement from the damaged state whereas the GFRP repair improved 248% in terms of the ultimate strength. A comparison of the behaviour between CFRP and GFRP repair is also highlighted in the study. Various parameters like stiffness, ductility, load-displacement behaviour and failure modes of these FRP repairs for damaged I-beams are discussed in detail. Overall, the results from the study portray the adequacy of an FRP rehabilitation to reinstate the strength from such structural damages in I-beams.
Experimental and FNPT-RANS Investigations Into Gap-Excitation and Vortex Dynamics in a Rectangular Moonpool Interacting With Focused Waves
Authors: Saincher Shaswat , Gongalla John Wesly , Vineesh P. , Sriram V.
Published: October 2021

Moonpools are designed to provide a calm environment for lowering of equipment from ships. Considerable research effort has been invested towards understanding water column excitation within a moonpool. However, most recent investigations consider regular waves. The nature of interaction between focused waves and a moonpool is not well-understood; the present work strives to fill this research gap. A series of experiments have been carried out in a 22 m long glass flume in the Department of Ocean Engineering at IIT Madras. Two identical cuboidal boxes were affixed with a 0.15 m gap representing a rectangular moonpool. Focused waves based on a constant steepness spectrum were generated in 0.6 m water depth by a piston-type wave-paddle. The focusing point was set at the center of the moonpool and wave-focusing experiments were performed with and without the twin-body. Wave elevation at various locations along the flume was measured using five wave-gauges. Next, the experiments were numerically replicated using the in-house codes IITM-FNPT2D (for inviscid wave generation) and IITM-RANS3D (for fully viscous wave-structure interaction). Gap-excitation at the instant of focusing has been quantified and correlated with focused wave characteristics and with dynamics of spanwise vortices generated at the edges of the moonpool.
Managing Flow Induced Vibration in Subsea Jumpers
Authors: Naik Rakshith , Urthaler Yetzirah , McNeill Scot , Boubenider Rafik
Published: October 2021

Certain subsea jumper design features coupled with operating conditions can lead to Flow Induced Vibration (FIV) of subsea jumpers. Excessive FIV can result in accumulation of allowable fatigue damage prior to the end of jumper service life. For this reason, an extensive FIV management program was instated for a large development in the Gulf of Mexico (GOM) where FIV had been observed.

The program consisted of in-situ measurement, modeling and analysis. Selected well and flowline jumpers were outfitted with subsea instrumentation for dedicated vibration testing. Finite Element (FE) models were developed for each jumper and refined to match the dynamic properties extracted from the measured data. Fatigue analysis was then carried out using the refined FE model and measured response data. If warranted by the analysis results, action was taken to mitigate the deleterious effects of FIV. Details on modeling and data analysis were published in [5]. Herein, we focus on the overall findings and lessons learned over the duration of the program. The following topics from the program are discussed in detail:

1. In-situ vibration measurement

2. Overall vibration trends with flow rate and lack of correlation of FIV to flow intensity (rho-v-squared);

3. Vibration and fatigue performance of flowline jumpers vs. well jumpers

4. Fatigue analysis conservatism

Reliance on screening calculations or predictive FE analysis could lead to overly conservative operational limits or a high degree of fatigue life uncertainty in conditions vulnerable to FIV. It is proposed that in-situ vibration measurements followed by analysis of the measured data in alignment with operating conditions is the best practice to obtain a realistic understanding of subsea jumper integrity to ensure safe and reliable operation of the subsea system.

The findings from the FIV management program provide valuable insight for the subsea industry, particularly in the areas of integrity management of in-service subsea jumpers; in-situ instrumentation and vibration measurements and limitations associated with predictive analysis of jumper FIV. If learnings, such as those discussed here, are fed back into design, analysis and monitoring guidelines for subsea equipment, the understanding and management of FIV could be dramatically enhanced compared to the current industry practice.
Machine Learning Prediction and Reliability Analysis Applied to Subsea Spool and Jumper Design
Authors: Song Mengdi , Gheroufella Massyl , Chartier Paul
Published: October 2021

In subsea pipelines projects, the design of rigid spool and jumper can be a challenging and time-consuming task. The selected spool layout for connecting the pipelines to the subsea structures, including the number of bends and leg lengths, must offer the flexibility to accommodate the pipeline thermal expansion, the pipe-lay target box and misalignments associated with the post-lay survey metrology and spool fabrication. The analysis results are considerably affected by many uncertainties involved. Consequently, a very large amount of calculations is required to assess the full combination of uncertainties and to capture the worst-case scenario.

Rather than applying the deterministic solution, this paper uses machine learning prediction to significantly improve the efficiency of the design process. In addition, thanks to the fast predictive model using machine learning algorithms, the uncertainty quantification and propagation analysis using probabilistic statistical method becomes feasible in terms of CPU time and can be incorporated into the design process to evaluate the reliability of the outputs. The latter allows us to perform a systematic probabilistic design by considering a certain level of acceptance on the probability of failure, for example as per DNVGL design code.

The machine learning predictive modelling and the reliability analysis based upon the probability distribution of the uncertainties are introduced and explained in this paper. Some project examples are shown to highlight the method’s comprehensive nature and efficient characteristics.
Application of Energy Saving Bow Shape in Actual Seas to JBC
Authors: Sakurada Akiko , Tsujimoto Masaru , Yokota Saori
Published: October 2021

Energy Efficiency Design Index (EEDI) entered Phase 2 in 2020. In this situation, ship performance in actual seas is more important than ever.

As an energy saving bow shape in actual seas, the authors are developing a bow shape named “COVE (Concave shape optimized in waves)”. The aim of COVE is to improve performance in waves without deteriorating performance in a calm sea by transformation above the static swell up at the target speed. Since the bow shape is concave above the static swell up, COVE reduces waves reflected forward because the most concave line has a fine triangular shape instead of the blunt shape of the original.

In this paper, COVE is applied to a Capesize bulk carrier, the JBC (Japan Bulk Carrier). The parameters of COVE are examined and the shape is optimized for the JBC. The effect of COVE is validated by tank tests in terms of wave lengths, wave angles, wave heights and ship speeds.

The results clarified the fact that COVE reduces added resistance in waves by approximately 30 % in head waves compared with the original shape. Validity was verified by the radiating wave shape and the side wall wave form recorded by a video camera in the tests.
Adaptive Constraint Handling in Optimization of Complex Structures by Using Machine Learning
Authors: Cai Yuecheng , Jelovica Jasmin
Published: October 2021

Optimization of complex systems requires robust and computationally efficient global search algorithms. Constraints make this a very difficult task, significantly slowing down an algorithm, and can even prevent finding the true Pareto front. This study continues the development of a recently proposed repair approach that exploits infeasible designs to increase computational efficiency of a prominent genetic algorithm, and to find a wider spread of the Pareto front. This paper proposes adaptive and automatized discovery of sensitivity of constraints to variables, i.e. the link, which needed direct designer’s input in the previous version of the repair approach. This is achieved by using machine learning in the form of artificial neural networks (ANN). A surrogate model is afterwards utilized in optimization based on ANN. The proposed approach is used for the recently proposed constraint handling implemented into NSGA-II optimization algorithm. The proposed framework is compared with two other constraint handling methods. The performance is analyzed on a structural optimization of a 178 m long chemical tanker which needs to fulfil class society’s criteria for strength. The results show that the proposed framework is competitive in terms of convergence and spread of the front. This is achieved while discovering the link automatically using ANN, without an input from a user. In addition, computational time is reduced by 60%.
Optimization of Fracturing Parameters in Changning Shale Based on a New Comprehensive Multi-Factor Analysis Method
Authors: Zeng Bo , Liu Jian , Song Yi , Zhou Xiaojin , Guo Xingwu , Zhao Zhiheng , Li Minghui , Zhou Fujian
Published: October 2021

Horizontal well multi-cluster fracturing technology is the most effective technical approach to exploit unconventional reservoirs (such as shale). The hydrocarbon productivity after fracturing often depends on the selection of fracturing location and fracturing parameters. However, these influencing parameters are very diverse and coupled with each other. Numerical simulation methods and laboratory experiment methods are often complicated to reflect the nonlinear relationship. Therefore, this study develops a new multi-factor analysis method based on field data to explore fracturing parameters’ weights that affect the hydrocarbon productivity after fracturing. This method combined the grey correlation method and entropy weight method to establish a combined weight analysis model. This method can comprehensively evaluate the influence factors on the post-fracturing productivity and ensure the accuracy of the obtained results through a field test. In our study, the influence of geological and fracturing parameters on 50 horizontal wells in Changning Shale is analyzed using the new method. These 50 wells are from the same block but have different values of fracturing parameters. The analysis results show that the fracturing parameters’ weight rankings on the post-fracturing productivity are fluid injection intensity, injection sand intensity, cluster spacing, injection rate, stage length, and average pump pressure. The weight rankings of geologic parameters affecting post-fracturing productivity are total gas content, brittle mineral content, porosity, Young’s modulus, minimum principal stress, total organic carbon, Poisson’s ratio, and maximum principal stress. Our study provides a new means of analyzing the influential factors of the in-situ hydraulic fracturing. Also, it gives a helpful guide for the selection of fracturing parameters in Changning Shale.
A Neural Network Time Dependent Hydrodynamic Force Model for Forced Two-Degree-Of-Freedom Sinusoidal Motion of a Circular Cylinder in a Free Stream
Authors: Aktosun Erdem , Xiros Nikolaos I. , Dahl Jason M.
Published: October 2021

A data-driven hydrodynamic force model is developed to model the dynamic forces on an oscillating circular cylinder for flow conditions where Vortex-Induced-Vibrations (VIV) are known to occur. The model is developed for use in future control systems to improve VIV-based energy harvesting. The dynamic model is empirical, utilizing force measurements obtained for a large set of forced motion experiments, spanning a range of parametric values that prescribe the kinematics of the cylinder motion. The model includes the dynamics of a circular cylinder undergoing forced combined in-line and cross-flow motion in a free stream. The experiments were conducted in a fully automated towing tank where parameters of in-line amplitude of motion, cross-flow amplitude of motion, reduced velocity, and phase difference between in-line and cross-flow motion were varied over nearly 10,000 experiments. All experiments were carried out at a constant Reynolds number of 7620. A feed forward neural network is trained using the force database to develop a time dependent model of forces on the cylinder for given kinematic conditions. Selected outputs of the force model are presented, providing a basis for future synthesis in energy harvesting control applications.
Quasi-Steady Analysis of Impulse Turbine Under Reciprocating Flow
Authors: Yu Yang , Zhao Mingren , Li Zhenmian , Yu Jianxing , Gao Yang , Zhao Yu
Published: October 2021

The impulse turbine, which is a part of an oscillating wave column, plays an indispensable role in wave energy conversion. In this paper, a self-rectifying impulse turbine has been investigated numerically under reciprocating flow and the quasi-steady analysis method of the turbine has been studied. Firstly, the numerical model was validated by corresponding experiment results. Then, the reciprocating flow condition was accurately simulated with the method of setting double velocity inlets. The results showed that there existed hysteretic loops in turbine performance curves. And different pressure drops in acceleration and deceleration led to this hysteretic characteristic. Finally, in order to investigate quasi-steady analysis method, the frequency and amplitude of the reciprocating flow were changed respectively and the results were compared with those of steady flow. It has been found that hysteretic loops are distributed around the curves of steady flow. When the frequency is lower or amplitude is smaller, the results of reciprocating flow are closer to those of steady flow. In conclusion, the performance of steady flow can be used to predict the performance of reciprocating flow with little velocity change in a short time, which reveals the feasibility of quasi-steady analysis method.
Cyclic Response and Instability Analysis of Seabed With Cohesionless Soils Due to Surging Waves
Authors: Rafiei Amin , Gabr M. A. , Rahman M. S. , Ghayoomi Majid
Published: October 2021

Surface waves may generate significant loadings on the seabed destabilizing sediments and the supporting marine structures. This threat is more pronounced in shallower water depths where the cyclic wave loading may induce residual pore water pressure in sediments triggering soil liquefaction. In this paper, a coupled numerical framework is presented to evaluate the interaction of waves and horizontal seabed considering nonlinear cyclic behavior of the cohesionless soil. A simple experimental model is employed for concurrent simulation of nonlinear buildup of pore pressure and deformation of saturated sand subjected to the cyclic loadings. The model (in elemental scale) is incorporated into a finite element code to solve the interaction of wave and seabed. Poro-elastoplastic response of the seabed is obtained by modifying the Biot’s coupled flow-and-deformation equations by adding equivalent nodal force terms associated with residual deformations of the soil. Potential flow theory is adopted for the fluid domain to model wave-induced pressure and flow fields. The governing equations and boundary conditions are solved using finite element analysis in time domain. The numerical framework is verified against results of cyclic triaxial compression tests and analytical solutions. Parametric studies are conducted to evaluate the effects of wave characteristics on triggering the residual liquefaction. The numerical results indicate good agreements with experimental measures. The results also show that for large waves, the progressive buildup of pore pressure in sediments may become high enough, leading to residual liquefaction. The details of the numerical model and the potential of residual liquefaction within the seabed soil are discussed.
Development of Deep Draft Semi-Submersible FPU Hull (Casting-Free) Targets for Oil Field in Gulf of Mexico
Authors: Yuck Raehyoung , Kang Daehoon , Han Ik-seung , Kim Eungsu , Kim Munsung , Shin Ki-young , Park Jong-woo , Kim Tae-min , Kang Sang-gu
Published: October 2021

A deep draft semi-submersible hull has been developed as a standardization concept which can support the topside structures up to the facility weight for the specific level of daily oil production in GOM (Gulf of Mexico).

The designed hull has the optimized dimensions of ring pontoon and four columns for coping with the weight change of topside and the innovated hull shape to eliminate the casting which is normally used at the corner node area where high stress concentrated on. The hull form also has the good global motion in waves, winds and currents to be able to use the SCR (Steel Catenary Riser).

The mooring systems are designed for water depths of 1,500m as a standard design concept of hull including mooring lines (3 × 4). The global performance is validated for the maximum offset, the mooring line tension and the acceleration. The possibility of SCR usage is also investigated with the fully coupled time-domain analysis to confirm that the designed hull form has the suitable hydrodynamic characteristics to permit the minimum vertical motion performance for SCR.

Throughout the global performance and mooring analysis, the designed Semi-FPU fulfills all stability requirements of rules and codes specified in design of basis for both intact and damaged conditions, and has good motion characteristics such as inclination, acceleration, sectional loads and air gap and mooring system compliance with design criteria in the view point of mooring tension, offset and fatigue damage.

Also, the global structural strength analysis has been performed to extract stresses and displacements where local points which are pontoon-column connection areas from the global model. The local points need to reinforce during detail design stage from buckling, yielding and fatigue analysis for normal operating and extreme storm conditions.
URANS Simulations of a Cruise Ship in Crabbing Motion
Authors: Zou Lu , Zou Zao-jian
Published: October 2021

In ship manoeuvrability, the crabbing test is critical to evaluate the hydrodynamic quantities for the guidance of an efficient and safe berthing or unberthing manoeuvres. In the present study, the crabbing performance of a cruise ship is investigated by an unsteady Reynolds-averaged Navier-Stokes (URANS) method considering the instantaneous relative motion between the ship and the quay. In the numerical simulations, the cruise ship is approaching the quay wall at a constant lateral speed. The crabbing motion with five degrees of freedom is modeled by the dynamic overset mesh technique, while the free surface elevation is simulated by the Volume of Fluid method. For reliable predictions of the crabbing performances, the timestep dependency study is conducted and a suitable time step is determined. From the computations, the hydrodynamic performances of the cruise ship, including forces and moments, as well as the surge, sinkage, roll, trim and yaw motions are predicted. The numerical results indicate variations of the hydrodynamic quantities under the impacts of ship speed and blockage effects by the quay wall. The present results can be used to evaluate the crabbing ability of the cruise ship and to provide guidance for estimating and designing the crabbing model test in further investigations.
Settling Behavior of Particles in Bubble Containing Newtonian Fluids: Experimental Study and Model Development
Authors: Jing Silin , Song Xianzhi , Zhu Zhaopeng , Yu Buwen , Duan Shiming
Published: October 2021

Accurate description of cuttings slippage in the gas-liquid phase is of great significance for wellbore cleaning and the control accuracy of bottom hole pressure during MPD. In this study, the wellbore bubble flow environment was simulated by a constant pressure air pump and the transparent wellbore, and the settling characteristics of spherical particles under different gas volume concentrations were recorded and analyzed by highspeed photography. A total of 225 tests were conducted to analyze the influence of particle diameter (1–12mm), particle density (2700–7860kg/m^3), liquid viscosity and bubble volume concentration on particle settling velocity. Gas drag force is defined to quantitatively evaluate the bubble’s resistance to particle slippage. The relationship between bubble drag coefficient and particle Reynolds number is obtained by fitting the experimental results. An explicit settling velocity equation is established by introducing Archimedes number. This explicit equation with an average relative error of only 8.09% can directly predict the terminal settling velocity of the sphere in bubble containing Newtonian fluids. The models for predicting bubble drag coefficient and the terminal settling velocity are valid with particle Reynolds number ranging from 0.05 to 167 and bubble volume concentration ranging from 3.0% to 20.0%. Besides, a trial-and-error procedure and an illustrative example are presented to show how to calculate bubble drag coefficient and settling velocity in bubble containing fluids. The results of this study will provide the theoretical basis for wellbore cleaning and accurate downhole pressure to further improve the performance of MPD in treating gas influx.
Estimation of Welding-Induced Plastic Zone Size and Residual Stress Levels: Linear Heat Input Approximation
Authors: Bhardwaj Sachin , Ratnayake R. M. Chandima
Published: October 2021

Welding is a highly nonlinear temperature distribution process, where the presence of high-temperature gradients leads to the development of significantly high residual stress levels, up to and/or beyond the material yield strength magnitude and localized plastic deformation. To achieve the desired dimensional accuracy, determination of plastic zone size, shape, and location is critically important in reducing or controlling final distortions, decreasing the residual stress according to length scale, and defining the optimum sequence of the welding process. The plastic zone caused by welding has been found to be directly proportional to linear heat input, defined in (J/mm). The use of actual linear heat input in the estimation of welding-induced residual stress in finite element models often results in an overestimation of heat transferred to the fusion zone of the metal. This manuscript highlights the importance of estimating plastic zone, developed during thermal processes like welding, and its role in mitigating final distortion by using a 3-bar model for the determination of final residual stresses. In the second part, previously developed analytical linear heat input solution for 2D residual stress models is discussed and further demonstrated using examples from open literature. Lastly, a sequentially uncoupled thermal and thermo-mechanical finite element analysis (FEA) is performed, using a generalized plane strain element, and concluded by validation of the numerically developed plastic zone size with analytically developed solutions.
Multiphase Flow Induced Vibrations at High Pressure: CFD Analysis of Multiphase Forces
Authors: Emmerson Paul , Lewis Mike , Barton Neil , Orre Steinar , Lunde Knud , Klinkenberg Arnout , Macchion Olivier , Challabotla Niranjan Reddy , Belfroid Stefan
Published: October 2021

CFD analysis of a high pressure 2” pipe test loop with water-gas flow was undertaken using three different solvers. Multiphase flow induced forces were predicted on the bends at a range of operating pressures between 10 and 80 barg and compared with forces reconstructed from vibration measurements.

Overall the three different CFD solvers predicted consistent results. The fluid forces predicted on the bends of the double U-loop test rig have a good range of values compared to the test reconstructed forces. The forces predicted at low pressure were in line with the experimental reconstructed values, whilst at high pressure all three CFD solvers predicted higher forces. The trend of the forces reducing with increased operating pressure, evident in test, was matched by one of the CFD methods, but less well by the other two. At low operating pressure the forces are dominated by the momentum of the liquid in the multiphase flow, whilst at high pressure the pressure fluctuations and turbulent effects will be more important. All three CFD solvers use VOF methods and above about 40 barg it is possible that they struggle to fully resolve the flow behaviour, which will be more influenced by bubble and droplet entrainment and turbulence.

Multiphase flow can induce high amplitude vibrations in piping systems, potentially leading to fatigue failures. CFD modelling offers a potentially powerful tool to provide the flow induced forces required for assessing and diagnosing multiphase flow induced pipework vibration problems in hydrocarbon production systems.
Hydrodynamic Impact on Wedges During Water Entry
Authors: de Oliveira Costa Daniel , Sena Sales Junior Joel , Fernandes Antonio Carlos , Corrêa Rodrigo dos Santos
Published: October 2021

The problem of water entry of wedges represents one of the most classic research topics in fluid mechanics. Along the past decades, many different analytical methods have been proposed to calculate pressure distribution and peak loads during the water entry, such as Wagner (1932) and Dobrovol’skaya (1969). Zhao and Faltinsen (1993) and Mei (1995) present numerical solutions based on potential theory assumptions (inviscid, irrotational and incompressible flow). For more complex geometries and cases these methods might not be accurate enough due to the simplifications assumed, and in these cases the use of computational fluid dynamics (CFD) might be an interest tool to provide more accurate analysis.

This work presents CFD results for different conditions of water entry of 2D wedges. The simulations were performed with a marine dedicated flow solver, FINE™/Marine from NUMECA, which features an unsteady Reynolds-averaged Navier-Stokes (URANS) solver and a finite volume method to perform spatial discretization. The multiphase flow is represented through the Volume of Fluid (VOF) method for incompressible and nonmiscible fluids. Different water entry conditions are explored. The effect of the mesh size, time step and other setup parameters over the results are discussed for simulations with 2D wedges to extend to other studies of water impact. The wedge velocity and hydrodynamic pressure distribution along the model’s face are monitored during the water entry and compared to experimental data from previous publication (Yettou et al, 2006) for water entry of wedges during free fall.
Experimental Investigation of the Coupling Between Aero- and Hydrodynamical Loads On A 12 MW Semi-Submersible Floating Wind Turbine
Authors: Thys Maxime , Souza Carlos , Sauder Thomas , Fonseca Nuno , Berthelsen Petter Andreas , Engebretsen Espen , Haslum Herbjørn
Published: October 2021

Model tests were performed with a model of the INO WINDMOOR 12 MW floating wind turbine in the Ocean Basin at SINTEF Ocean. The tests were done at a scale of 1:40. RealTime Hybrid Model testing was used for the modelling of the wind turbine rotor and aerodynamic loads. A subset of the results is analysed to study the influence of the wind on the platform motions, the acceleration at tower top, the loads at base of tower and the relative wave elevation. The study is based on the comparison of the quantities of interest for different tests with the same moderate sea-state but with different wind modelling: no wind, constant thrust force, turbulent wind of 11.5 m/s and turbulent wind of 25 m/s.

The wind modelling has a minimal influence on the platform surge and pitch response in the wave-frequency range. On the other hand, the aerodynamic loads, including wind turbine controller dynamics and turbulent wind, has an important impact on the low-frequency surge and pitch response.

The aerodynamic loads are important for the loads at tower base due to the dominance of the tower-RNA induced gravitational loads at low-frequency.

Maximum relative wave elevation was found to be mainly dependent on the thrust induced mean pitch angle.