bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of Flowzan as Non-Newtonian Cutting Transport Fluid in Directional Drilling Applications via Electrical Resistance Tomography Method
Authors: Khan Muhammad Saad , Barooh Abinash , Rahman Mohammad Azizur , Hassan Ibrahim , Hasan Rashid 
Published: October 2021

Abstract
In-situ cutting transport measurement is essential to understand the hydrodynamics and operational parameters required for efficient annulus cleaning. Electrical resistance tomography (ERT) has been a promising method in many industrial applications. This study aimed to provide comprehensive information on the use of a non-invasive ERT method to examine the volume fraction of solids in the presence of non-Newtonian fluid (0.5 wt percent of Flowzan) in a directional drilling annulus (80–90° from vertical orientation). The experiments were performed in a horizontal flow loop system where the annulus segment was 240 (6.16 m) inch long with an inner and outer diameter of 2.5 inches (6.4 cm) and 4.5 inches (11.4 cm), respectively. The results obtained indicated that the ERT device could effectively detect the volume fraction of the solids in the presence of non-Newtonian fluid (Flowzan) under different drilling conditions. Results also showed that the annulus’ successful cleaning was observed with an increase in fluid mass flow rates indicated the relative increase in cuttings volumes (AVF = 7 to 9%). Besides, the rotation of the drill pipe often had a beneficial effect on cutting transport. Furthermore, it was observed that both (30%) eccentricity and inclination (80–85 °) cause a reduction in cutting volume fraction. Therefore, this study will provide an avenue for the industrial implementation of in situ ERT measurement technology in directional drilling operations, particularly in the case of non-Newtonian drilling fluids.
Advances on Reduced-Order Modeling of Floating Offshore Wind Turbines
Authors: Lemmer Frank , Yu Wei , Steinacker Heiner , Skandali Danai , Raach Steffen 
Published: October 2021

Abstract
Aero-hydro-servo-elastic modeling of Floating Offshore Wind Turbines (FOWTs) is a key component in the design process of various components of the system. Different approaches to order reduction have been investigated with the aim of improving structural design, manufacturing, transport and installation, but also the dynamic behavior, which is largely affected by the blade pitch controller. The present work builds on previous works on the SLOW (Simplified Low-Order Wind Turbine) code, which has already been used for the above purposes, including controller design. While the previous rigid rotor model gives good controllers in most cases, we investigate in the present work the question if aero-elastic effects in the design model can improve advanced controllers. The SLOW model is extended for the flap-wise bending and coupled to NREL’s AeroDyn, linearized and verified with the OlavOlsen OO-Star Wind Floater Semi 10MW public FOWT model. The results show that the nonlinear and linear reduced-order SLOW models agree well against OpenFAST. The state-feedback Linear Quadratic Regulator (LQR) applied with the same weight functions to both models, the old actuator disk, and the new aero-elastic model shows that the LQR becomes more sensitive to nonlinear excitation and that the state feedback matrix is significantly different, which has an effect on the performance and potentially also on the robustness. Thus modeling uncertainties might even be more critical for the LQR of the higher-fidelity model.
A Joint-Industry Effort to Develop and Verify CFD Modeling Practice for Vortex-Induced Motion of a Deep-Draft Semi-Submersible
Authors: Jang Hyunchul , Kim Dae-Hyun , Agrawal Madhusuden , Loubeyre Sebastien , Lee Dongwhan , Huang Jerry , Law Yun Zhi , Magee Allan , Koop Arjen 
Published: October 2021

Abstract
Platform Vortex Induced Motion (VIM) is an important cause of fatigue damage on risers and mooring lines connected to deep-draft semi-submersible floating platforms. The VIM design criteria have been typically obtained from towing tank model testing. Recently, computational fluid dynamics (CFD) analysis has been used to assess the VIM response and to augment the understanding of physical model test results. A joint industry effort has been conducted for developing and verifying a CFD modeling practice for the semi-submersible VIM through a working group of the Reproducible Offshore CFD JIP. The objectives of the working group are to write a CFD modeling practice document based on existing practices validated for model test data, and to verify the written practice by blind calculations with five CFD practitioners acting as verifiers.
This paper presents the working group’s verification process, consisting of two stages. In the initial verification stage, the verifiers independently performed free-decay tests for 3-DOF motions (surge, sway, yaw) to check if the mechanical system in the CFD model is the same as in the benchmark test. Additionally, VIM simulations were conducted at two current headings with a reduced velocity within the lock-in range, where large sway motion responses are expected,. In the final verification stage, the verifiers performed a complete set of test cases with small revisions of their CFD models based on the results from the initial verification. The VIM responses from these blind calculations are presented, showing close agreement with the model test data.
Qualification Criteria for the Verification of Numerical Waves – Part 1: Potential-Based Numerical Wave Tank (PNWT)
Authors: Fouques Sébastien , Croonenborghs Eloïse , Koop Arjen , Lim Ho-Joon , Kim Jang , Zhao Binbin , Canard Maxime , Ducrozet Guillaume , Bouscasse Benjamin , Wang Weizhi , Bihs Hans 
Published: October 2021

Abstract
There is an increasing trend towards using numerical wave simulations for the design of offshore structures, especially for the stochastic prediction of nonlinear wave loads like those related to air-gap and wave impact. Unlike experimental facilities, where the complex nonlinear physics of wave propagation is simply enforced by the laws of nature, numerical wave tanks (NWTs) rely on assumptions and simplifications to solve the propagation equations in a reasonable amount of time. It is therefore important to verify the quality of the waves generated by NWTs in terms of realistic physical properties.
As part of the effort to develop reliable numerical wave modeling practices in the framework of the “Reproducible Offshore CFD JIP”, qualification criteria are formulated for the wave solutions generated from either potential-flow based or CFD-based codes. The criteria have been developed based on experiences from physical wave tank tests and theoretical/numerical studies. They are being evaluated using results from several numerical models and available benchmark data. This paper presents the proposed qualification criteria and on-going evaluation efforts by comparing results from different codes.
Numerical Simulation of Full-Scale Ship Self-Propulsion for Japan Bulk Carrier
Authors: Xu Jing , Zhou Yujie , Yu Jiawei , Deng Weihua , Feng Dakui 
Published: October 2021

Abstract
The self-propulsion simulations of JBC (Japan Bulk Carrier) were performed in model and full scale with two approach: one is the body force method using steady blade element theory (lift lines theory) and infinite blade propeller, the other is 3-D discretized propeller method. All simulations were investigated using an in-house CFD code which is based on the finite difference method to discretize the governing equations. A dynamic overset technique was used and any revolutions of the propeller can be achieved in the simulation. In order to obtain the self-propulsion point, a PI speed controller was utilized to adjust the rate of revolutions of the propeller. To obtain self-propulsion factors, resistance and open water tests are also computed. Thrust identity method was used to obtain wake fraction. The full scale total resistance coefficient was obtained according two extrapolation methods: the first is the ITTC 1978 recommended procedure, while the second is the extrapolation method based on Grigson friction line. Wake fraction was revised following ITTC recommended procedures in full scale. All the results of the simulation have a reasonable agreement with experimental results. The computational results presented in this paper also provide evidence to the full scale self-propulsion prediction ability of the in-house code.
Dynamic Responses of the State-of-the-Art Floating System Integrating a Wind Turbine With a Steel Fish Farming Cage: Model Tests vs. Numerical Simulations
Authors: Lei Yu , Zheng Xiang Yuan , Zheng Hua-dong 
Published: October 2021

Abstract
This work is dedicated to comparing the experimental and numerical results of the dynamic responses of a novel floating system integrating a floating offshore wind turbine with a steel fish farming cage (FOWT-SFFC) under wind and wave loadings. The patents of this floating system have been successfully licensed recently in China and USA.
The experimental study is carried out in the Ocean Basin of Tsinghua Shenzhen International Graduate School, with a Froude scaling of 1:30. A small commercial wind turbine is used to produce the scaled wind loads on FOWT-SFFC in terms of the similarity of thrust force.
In this paper, the setup of model tests is described first. Second, a numerical model of prototype FOWT-SFFC is built in the software OrcaFlex. Then, this numerical model is calibrated and updated by the results of free decay tests and static offset tests in the basin. The numerical model also adopts three sets of drag coefficients. Finally, the experimental results of FOWT-SFFC under a variety of load cases are presented and compared with the numerical simulation results. They include seakeeping tests for hydrodynamic motion response amplitude operators (RAOs) and dynamic responses corresponding to normal operating and survival conditions. The numerical simulation results show that, though they are in good agreement with model test data especially on time records of dynamic responses, they are sensitive to the selection of drag coefficients particularly on extreme values and low-frequency spectral contents. Appropriate drag coefficients are suggested to be used in the numerical model for a specific environmental condition. Drag coefficients benchmarked from the free decay tests may not be suitable for moderate and harsh wave conditions.
Cement Sheath Integrity During High Temperature Geothermal Well Operations
Authors: Vrålstad Torbjørn , Skorpa Ragnhild , Opedal Nils , Todorovic Jelena , Agofack Nicolaine , Hoang Nguyen-Hieu 
Published: October 2021

Abstract
Development of geothermal energy sources is an important contribution to ensure the “green shift” from fossil fuels to more sustainable sources of energy. Currently, most geothermal wells operate at temperature range of 150–300° C, but development of super-high temperature geothermal reservoirs may be needed to increase power production. However, the high temperature conditions to be found in such wells, up to 400–500 °C, are very challenging and may be detrimental for the integrity of well cement.
In this paper, several cement integrity challenges for high temperature geothermal wells are reviewed, such as mechanical failures during well start-up and potential shut-in periods, and long-term issues caused by chemical alterations of the cement during high temperature exposure. Experimental tests have been performed with two different, potential geothermal well cement systems: a Portland-based system with silica flour and MicroSilica as additives, and a non-Portland, calcium aluminate cement system. For both cement systems, high temperature ageing tests have been performed at 500 °C for 8 weeks, where unconfined mechanical properties were determined before and after exposure. Furthermore, down-scaled tests of radial crack formation in casing-cement-rock samples have been performed, as simplified functions tests of cement sheath integrity during well start-up.
Well Integrity Enabled by Digital Workflow
Authors: Brechan (Wellviz) B. , Teigland A. , Dale S. , Sangesland S. 
Published: October 2021

Abstract
Emerging technologies are expected to provide step changes in many areas within planning, making and production of wells. The main topic of this paper covers in a digital workflow, where the different disciplines contributions to well integrity are expected to be on a fully digital format. All phases in the lifecycle of wells are integrated into one digital process, where possible improvements are enabled by the transition from a human oriented work process to a software oriented (human supported) process. This transition has taken place in several other comparable energy and capital-intensive industries.
Today, some wells have the new fiber optics that enables a range of opportunities for improvement of well integrity. Distributed Acoustic Sensing (DAS) has measurements for every meter, which provides new aspects such as in situ measurements during cement jobs and drilling. Other applications of the new fiber optic technology are monitoring of gas migration, source of sustained casing pressure and other measurements which have the potential to develop into standard procedures or even regulatory requirements. With gas migration, corrosion and other changes affecting the integrity of the well construction, integrity can be re-modelled and updated automatically in a fully digital workflow to understand the safety margins. A part of this digital process is automating the risk level for each well and the entire asset. These processes and the prototype of the automated risk assessment are possible in a fully digital process, where planning and well construction commence with support from modern well planning and integrity software.
Non-Linear Response Analysis of Jacket Supported Offshore Wind Turbine under Seismic Loads using Hilbert-Huang Transform
Authors: Kashyap Subham , Saha Nilanjan , Abhinav K. A. 
Published: October 2021

Abstract
The present work studies the performance of an offshore wind turbine system in an earthquake coupled with wave and wind loading. The NREL 5 MW offshore wind turbine, supported on the OC4 jacket [14], has been analysed within a finite element framework. A coupled model of hydrodynamics and soil-structure interaction has been implemented. The structure-foundation system is analysed under earthquakes recorded close to offshore waters and at sites with shear-wave velocities, classified under Site-Class D or Site-Class E as per API RP: 2EQ [8]. The soil conditions emulate characteristics of a prospective offshore wind turbine site along the west coast of India, which falls within the Site-Class D classification mentioned above. The geotechnical modelling is done as per the soil curves prescribed by the non-linear Winkler springs along the pile’s length. The complete analysis has been processed in a finite-element framework through the commercial program USFOS [16]. The Hilbert-Huang transform [29] of the tower-responses suggests the increased vulnerability to the resonance phenomenon with 1P and 3P loading. It also suggests an involvement of higher modes in the tower-response. The change in the frequency of the structure-foundation system during and post-earthquake has also been studied.
Time-dependent propensity-matched general population study of the effects of statin use on cancer risk in an interstitial lung disease and pulmonary fibrosis cohort
Authors: Yeh Jun-Jun , Lai Jung-Nien , Lin Cheng-Li , Hsu Chung-Y , Kao Chia-Hung 
Published: October 2021

ObjectiveTo determine the effect of statins on risk of cancer in patients with interstitial lung disease (ILD) and pulmonary fibrosis.SettingWe retrospectively enrolled patients with ILD and pulmonary fibrosis and divided them into two cohorts by statin use (statin users (n=10 036) and statin non-users (n=10 036)).ParticipantsWe selected patients with ILD and pulmonary fibrosis (N=53 862) from Taiwan’s National Health Insurance Research Database. Time-dependent Cox models were used to compare risk of cancer of propensity-matched statin users and non-users. Cumulative cancer incidence was analysed through Cox proportional regression. We calculated adjusted HRs (aHRs) and their 95% CIs for cancer after adjusting for sex, age, comorbidities, and use of inhaled corticosteroids, oral steroids and statins.ResultsCompared with statin non-users, the aHRs (95% CIs) for statin users were 0.60 (0.55 to 0.65) for cancer, 0.52 (0.35 to 0.78) for haematological malignancy, 0.52 (0.38 to 0.72) for cancer of the head and neck, 0.73 (0.59 to 0.89) for colorectal cancer, 0.34 (0.26 to 0.43) for liver cancer, 0.39 (0.23 to 0.67) for pancreatic cancer, 0.40 (0.17 to 0.96) for skin cancer, 0.67 (0.52 to 0.87) for breast cancer, 0.27 (0.14 to 0.54) for cervical cancer, 0.37 (0.30 to 0.46) for other immunological cancers, 0.73 (0.54 to 0.98) for bladder/kidney cancer and 0.88 (0.71 to 1.09) for lung cancer.ConclusionStatin use is associated with lower risk of cancer in the ILD and pulmonary fibrosis cohort.
Women’s perceptions and self-reports of excessive bleeding during and after delivery: findings from a mixed-methods study in Northern Nigeria
Authors: Yargawa Judith , Fottrell Edward , Hill Zelee 
Published: October 2021

ObjectivesTo explore lay perceptions of bleeding during and after delivery, and measure the frequency of self-reported indicators of bleeding.SettingYola, North-East Nigeria.ParticipantsWomen aged 15–49 years who delivered in the preceding 2 years of data collection period (2015–2016), and their family members who played key roles.MethodsData on perceptions of bleeding were collected through 7 focus group discussions, 21 in-depth interviews and 10 family interviews. Sampling was purposive and data were analysed thematically. A household survey was then conducted with 640 women using cluster sampling on postpartum bleeding indicators developed from the qualitative data; data were analysed descriptively.ResultsPerceptions of excessive bleeding fell under four themes: quantity of blood lost; rate/duration of blood flow; symptoms related to blood loss and receiving birth interventions/hearing comments from birth attendants. Young and less educated rural women had difficulty quantifying blood loss objectively, including when shown quantities using bottles. Respondents felt that acceptable blood loss levels depended on the individual woman and whether the blood is ‘good’ or ‘diseased/bad.’ Respondents believed that ‘diseased’ blood was a normal result of delivery and universally took steps to help it ‘come out.’ In the quantitative survey, indicators representing less blood loss were reported more frequently than those representing greater loss, for example, more women reported staining their clothes (33.6%) than the bed (18.1%) and the floor (6.2%). Overall, indicators related to quantity and rate of blood flow had higher frequencies compared with symptom and intervention-related/comment-related indicators.ConclusionWomen quantify bleeding during and after delivery in varied ways and some women do not see bleeding as problematic. This suggests the need for standard messaging to address subjectivity. The range of indicators and varied frequencies highlight the challenges of measuring excessive bleeding from self-reports. More work is needed in improving and testing validity of questions.
Protocol of a systematic review and network meta-analysis for the prevention and treatment of perinatal depression
Authors: Smith Robert David , Hung Sze Chai , Goh Joyce , Ip Hoi Lam , Fong Daniel Yee Tak , Ali Shehzad , Wilson Claire Anna , Lok Kris Yuet-Wan 
Published: October 2021

IntroductionPerinatal depression is common and can often lead to adverse health outcomes for mother and child. Multiple pharmacological and non-pharmacological treatments have been evaluated against usual care or placebo controls in meta-analyses for preventing and treating perinatal depression compared. It is not yet established which of these candidate treatments might be the optimal approach for prevention or treatment.Methods and analysisA systematic review and Bayesian network meta-analyses will be conducted. Eight electronic databases shall be searched for randomised controlled trials that have evaluated the effectiveness of treatments for prevention and/or treatment of perinatal depression. Screening of articles shall be conducted by two reviewers independently. One network meta-analysis shall evaluate the effectiveness of interventions in preventing depression during the perinatal period. A second network meta-analysis shall compare the effectiveness of treatments for depression symptoms in women with perinatal depression. Bayesian 95% credible intervals shall be used to estimate the pooled mean effect size of each treatment, and surface under cumulative ranking area will be used to rank the treatments’ effectiveness.Ethics and disseminationWe shall report our findings so that healthcare providers can make informed decisions on what might be the optimal approach for addressing perinatal depression to prevent cases and improve outcomes in those suffering from depression through knowledge exchange workshops, international conference presentations and journal article publications.PROSPERO registration numberCRD42020200081.
Healthcare professionals in COVID-19-intensive care units in Norway: preparedness and working conditions: a cohort study
Authors: Lie Irene , Stafseth Siv , Skogstad Laila , Hovland Ingvild Strand , Hovde Haakon , Ekeberg Øivind , Ræder Johan 
Published: October 2021

ObjectiveTo survey the healthcare professionals’ background and experiences from work with patients with COVID-19 in intensive care units (ICUs) during the first wave of the COVID-19 pandemic in Norway.DesignObservational cohort study.SettingCOVID-ICUs in 27 hospitals across Norway.ParticipantsHealthcare professionals (n=484): nurses (81%), medical doctors (9%) and leaders (10%), who responded to a secured, web-based questionnaire from 6 May 2020 to 15 July 2020.Primary and secondary measuresHealthcare professionals’: (1) professional and psychological preparedness to start working in COVID-ICUs, (2) factors associated with high degree of preparedness and (3) experience of working conditions.ResultsThe age of the respondents was 44.8±10 year (mean±SD), 78% were females, 92% had previous ICU working experience. A majority of the respondents reported professional (81%) and psychological (74%) preparedness for working in COVID-ICU. Factors significantly associated with high professional preparedness for working in COVID-19-ICU in a multivariate logistic model were previous ICU work experience (p<0.001) and participation in COVID-ICU simulation team training (p<0.001). High psychological preparedness was associated with higher age (p=0.003), living with spouse or partner (p=0.013), previous ICU work experience (p=0.042) and participation in COVID-ICU simulation team training (p=0.001). Working with new colleagues and new professional challenges were perceived as positive in a majority of the respondents, whereas 84% felt communication with coworkers to be challenging, 46% were afraid of being infected and 82% felt discomfort in denying access for patient relatives to the unit. Symptoms of sweating, tiredness, dehydration, headache, hunger, insecurity, mask irritation and delayed toilet visits were each reported by more than 50%.ConclusionsHealthcare professionals working during the first wave of COVID-ICU patients in Norway were qualified and prepared, but challenges and potential targets for future improvements were present.Trial registration numberNCT04372056.