bluuebunny/crossref_metadata_2025_split huggingface dataset:
Study of Tapping Process of Ti6Al4V Using Finite Element (FE) Simulation
Authors: Daneji Ali , Pervaiz Salman , Kannan Sathish 
Published: February 2021

Abstract
Finite element (FE) assisted numerical modeling approach is known as a popular approach to predict the machining performance of different machining operations. Tapping operation is a well-known manufacturing process that is used to cut threads efficiently. In the automotive and aerospace applications, precisely machined tapped holes are required in the small size deep holes. Tapping process creates thread in the hole and make it ready for fastening with other mating components. Tapping operation is considered as one of the most complex machining operations due to the presence of multi-flutes and multi-land involvement between the workpiece and cutter materials. The outcome of the tapping process results in the generation of threads and accepted as one of the most commonly employed in fastening methods for the joining of different machine components. Literature revealed that tapping process has been very rarely investigated using computational modeling approaches, as most of the available studies are experimental in nature. The experimental work for tapping operation can be very time and cost consuming because of the expensive fabrication of the cutting tools. It has also been observed experimentally that minor change in the threading profiles can generate significant difference in the cutting torque. A possible solution is to analyse the whole tapping operation using finite element (FE) assisted numerical simulation. Similarly, there will be limitation towards experiments if the workpiece material is expensive and difficult to cut.
It is a common observation in metal cutting industry that most of the times cutting tap results in breakage when exposed to the higher magnitude of torque. The current study is aimed on the finite element based computational investigations on the tapping process using Ti6Al4V as a workpiece material. High hot hardness and low thermal conductivity of the Ti6Al4V also plays a significant role towards the poor machining performance of the threading tool. Ti6Al4V is most commonly employed in the engineering applications where high strength to weight ratio and ability of operate at higher temperatures is required. Ti6Al4V is mainly utilized in the automotive, aerospace, biomedical and petrochemical industries. It has been identified that tapping operation is very rarely studied machining operation in the metal cutting scientific community. Different tapping process conditions were investigated computationally using finite element (FE) approach and as a result cutting forces, torques and power consumed were observed. The study provides a useful understanding towards the tapping process mechanics with respect to different cutting parameters.
Numerical Study of the Unsteady Flow Inside a Centrifugal Fan and its Downstream Pipe Using Detached Eddy Simulation
Authors: Cai Jian-Cheng , Zhang Jia-Qi , Yang Can 
Published: February 2021

Abstract
The 3-D unsteady turbulent flow inside a centrifugal fan and its downstream pipe is investigated at the best efficiency point (BEP) flow rate using the computational fluid dynamics (CFD) package ANSYS FLUENT. The impeller with an outlet diameter of 400 mm has 12 forward curved blades. The computational domain comprises four parts: the inlet part, the impeller, the volute, and the downstream pipe. The flow domain was meshed in ANSYS ICEM-CFD with structured hexahedron cells, and nearly 9 million cells were used. The Detached Eddy Simulation (DES) turbulence modelling approach was employed with this fine enough mesh scheme. The impeller was set as the rotating domain at a speed of 2900 rpm. A sliding mesh technique was applied to the interfaces in order to allow unsteady interactions between the rotating impeller and the stationary parts; the unsteady interactions generate pressure fluctuations inside the centrifugal fan. One impeller revolution is divided into 2048 time steps, in order to capture the transient flow phenomena with high resolution. Monitoring points were set along the volute casing profile, and along the downstream pipe centerline. When the numerical simulation became stable after several impeller revolutions, the statistics of the unsteady flow was initiated with a total of 16384 time steps (8 impeller revolutions) data. The time history data of the pressure and velocity magnitude at the monitoring points were saved and with Fourier transform applied to obtain the frequency spectra.
The time-averaged flow fields show clearly the static pressure rises gradually through the impeller, and further recovers from the velocity in the volute, and decreases gradually along the downstream pipe due to the friction. The mean pressure at the pressure side of the impeller blade is larger than it at the suction side, forming the circumferential nonuniform flow pattern. Owing to the forward-curved blades, large velocity region exists around the impellor exit, and the maximum velocity near the trailing edge can reach 1.5u2, where u2 is the circumferential velocity at the impeller outlet.
The root mean square (rms) value distribution of pressure fluctuations show that most parts inside the centrifugal fan undergo large pressure fluctuation with the magnitude about 10% of the reference dynamic pressure pref = 0.5ρu22; the maximum value locating at the tongue tip can reach 30% of pref. The pressure fluctuation magnitude decreases quickly along the outlet pipe: after 5D (D is the outlet pipe diameter) the magnitude is 0.5% of pref. The pressure and velocity fluctuation spectra at the monitoring points in the volute show striking discrete components at the blade-passing frequency (BPF) and its 2nd, 3rd harmonics. The BPF component has the maximum value of 15% of pref in the tongue region, and it decreases dramatically along the downstream pipe with the amplitude less than 0.2% of pref after 5D distance.
Investigation of Two-Phase Flow and Heat Transfer Inside Rotational Paper Dryers Using Three Different Multiphase Computational Models
Authors: Majeed Hamed , Barboza Pereira Victor , Wang Ting , D’Amico Joseph V. , Kononchek Chris 
Published: February 2021

Abstract
The paper industry uses cylinder dryers that employ steam to heat the paper web moving over the cylinder outer walls. As steam condenses, the condensate is accumulated inside the cylinder dryers. The condensate is evacuated using either stationary or rotary siphons. The form of condensate motion occurring inside the cylinder can be puddling, cascading or rimming depending on the size of the cylinder dryer, the rotating speed, the amount of condensate, and the surface finish of the cylinder dryer inner wall with or without ribs or grooves. The behavior of the condensate inside the cylinder dryers affects the heat transfer through the cylinder wall, the torque and power requirements of the dryer, and the performance of the condensate evacuation via siphons. To help improve the drying performance, it is important to understand the fundamental thermal-fluid physics in the rotational dryer. Thus, the objectives of this study are (a) to investigate the dynamic two-phase flow and heat transfer behavior inside the rotational paper dryer at different rotational speeds; (b) to employ three different multiphase computational models, the Volume of Fluid (VOF) model, the Mixture model, and the Eulerian-Eulerian (E-E) model, and compare their results. The results show that the E-E model better captures the physics of condensate behavior inside the dryer. It also predicts very well the rimming speed in comparison with the empirical correlation although it takes longer computational time than the VOF model. The mixture model doesn’t adequately capture the cascade and rimming physics due to excessive liquid dispersion. Based on the results, the categorization of the thermal-flow behavior of the liquid layer is expanded from the traditional three phases to five phases: puddling, transitional cascading, cascading, transitional rimming, and steady rimming. A detailed analysis of the rotating liquid layer behavior and its corresponding wall heat transfer passing through each phase is presented. Generally, the heat transfer increases during the initial puddling period, followed by oscillatory attenuation during the cascade period, finally reaches steady state after rimming is achieved.
Factors affecting health care users’ first contact with primary health care facilities in north eastern China, 2008–2018
Authors: Liao Ran , Liu Yaqian , Peng Shunzhuang , Feng Xing Lin 
Published: February 2021

BackgroundChina set out the vision to establishing a hierarchical medical system, with primary health care (PHC) facilities serving health care users’ first contact. Common ailments were listed, supported by a series of auxiliary policy measures. We aim to assess whether these policies were effective to prompt users’ preference to PHCs within these contexts.MethodsUsing data from three waves of National Health Service Survey, we examined trends in care users’ first contact with PHC facilities in Jilin, a north eastern province, during 2008–2018. We analysed trends and factors affecting care users’ choices, stratified by type of diseases and urban–rural settings.ResultsFrom 38 823 respondents, the survey identified 3302 health care users who sought outpatient care. 54.92% and 82.49% with diseases recommended to PHC, in urban and rural Jilin, respectively, contacted PHC facilities first. While 33.51% and 61.19% with diseases not recommended to PHC did so. Care users’ first contact with PHC facilities followed an inverse U shape during 2008–2018. Such trends were more profound among care users with hypertension and/or diabetes. Neither social health insurance coverage nor contracting with family doctors was associated with care users’ first contacts. Only 1.25% care users had referral experiences. Low perceived quality was the main barrier to choose PHC facilities.ConclusionHealth care users sought PHC in a chaotic manner in Jilin. None of the recent efforts seemed effective in prompting their preference to PHC facilities. Without levering quality of PHC, an effective hierarchical medical system could be hardly forged in China.
Does psychological distress directly increase risk of incident cardiovascular disease? Evidence from a prospective cohort study using a longer-term measure of distress
Authors: Welsh Jennifer , Banks Emily , Joshy Grace , Butterworth Peter , Strazdins Lyndall , Korda Rosemary J 
Published: February 2021

ObjectiveCardiovascular disease (CVD) incidence is elevated among people with psychological distress. However, whether the relationship is causal is unclear, partly due to methodological limitations, including limited evidence relating to longer-term rather than single time-point measures of distress. We compared CVD relative risks for psychological distress using single time-point and multi-time-point assessments using data from a large-scale cohort study.DesignWe used questionnaire data, with data collection at two time-points (time 1: between 2006 and 2009; time 2: between 2010 and 2015), from CVD-free and cancer-free 45 and Up Study participants, linked to hospitalisation and death records. The follow-up period began at time 2 and ended on 30 November 2017. Psychological distress was measured at both time-points using Kessler 10 (K10), allowing assessment of single time-point (at time 2: high (K10 score: 22–50) vs low (K10 score: <12)) and multi-time-point (high distress (K10 score: 22–50) at both time-points vs low distress (K10 score: <12) at both time-points) measures of distress. Cox regression quantified the association between distress and major CVD, with and without adjustment for sociodemographic and health-related characteristics, including functional limitations.ResultsAmong 83 906 respondents, 7350 CVD events occurred over 410 719 follow-up person-years (rate: 17.9 per 1000 person-years). Age-adjusted and sex-adjusted rates of major CVD were elevated by 50%–60% among those with high versus low distress for both the multi-time-point (HR=1.63, 95% CI 1.40 to 1.90) and single time-point (HR=1.53, 95% CI 1.39 to 1.69) assessments. HRs for both measures of distress attenuated with adjustment for sociodemographic and health-related characteristics, and there was little evidence of an association when functional limitations were taken into account (multi-time-point HR=1.09, 95% CI 0.93 to 1.27; single time-point HR=1.14, 95% CI 1.02 to 1.26).ConclusionIrrespective of whether a single time-point or multi-time-point measure is used, the distress–CVD relationship is substantively explained by sociodemographic characteristics and pre-existing physical health-related factors.
Effect of intensive treatment for schistosomiasis on immune responses to vaccines among rural Ugandan island adolescents: randomised controlled trial protocol A for the ‘POPulation differences in VACcine responses’ (POPVAC) programme
Authors: Nkurunungi Gyaviira , Zirimenya Ludoviko , Nassuuna Jacent , Natukunda Agnes , Kabuubi Prossy N , Niwagaba Emmanuel , Oduru Gloria , Kabami Grace , Amongin Rebecca , Mutebe Alex , Namutebi Milly , Zziwa Christopher , Amongi Susan , Ninsiima Caroline , Onen Caroline , Akello Florence , Sewankambo Moses , Kiwanuka Samuel , Kizindo Robert , Kaweesa James , Cose Stephen , Webb Emily , Elliott Alison M 
Published: February 2021

IntroductionSeveral licensed and investigational vaccines have lower efficacy, and induce impaired immune responses, in low-income versus high-income countries and in rural, versus urban, settings. Understanding these population differences is essential to optimising vaccine effectiveness in the tropics. We suggest that repeated exposure to and immunomodulation by chronic helminth infections partly explains population differences in vaccine response.Methods and analysisWe have designed an individually randomised, parallel group trial of intensive versus standard praziquantel (PZQ) intervention against schistosomiasis, to determine effects on vaccine response outcomes among school-going adolescents (9–17 years) from ruralSchistosoma mansoni-endemic Ugandan islands. Vaccines to be studied comprise BCG on day ‘zero’; yellow fever, oral typhoid and human papilloma virus (HPV) vaccines at week 4; and HPV and tetanus/diphtheria booster vaccine at week 28. The intensive arm will receive PZQ doses three times, each 2 weeks apart, before BCG immunisation, followed by a dose at week 8 and quarterly thereafter. The standard arm will receive PZQ at week 8 and 52. We expect to enrol 480 participants, with 80% infected withS. mansoniat the outset.Primary outcomes are BCG-specific interferon-γ ELISpot responses 8 weeks after BCG immunisation and for other vaccines, antibody responses to key vaccine antigens at 4 weeks after immunisation. Secondary analyses will determine the effects of intensive anthelminthic treatment on correlates of protective immunity, on waning of vaccine response, on priming versus boosting immunisations and onS. mansoniinfection status and intensity. Exploratory immunology assays using archived samples will enable assessment of mechanistic links between helminths and vaccine responses.Ethics and disseminationEthics approval has been obtained from relevant ethics committes of Uganda and UK. Results will be shared with Uganda Ministry of Health, relevant district councils, community leaders and study participants. Further dissemination will be done through conference proceedings and publications.Trial registration numberISRCTN60517191.
Effect of intermittent preventive treatment for malaria with dihydroartemisinin-piperaquine on immune responses to vaccines among rural Ugandan adolescents: randomised controlled trial protocol B for the ‘POPulation differences in VACcine responses’ (POPVAC) programme
Authors: Natukunda Agnes , Nkurunungi Gyaviira , Zirimenya Ludoviko , Nassuuna Jacent , Oduru Gloria , Amongin Rebecca , Kabuubi Prossy N , Mutebe Alex , Onen Caroline , Amongi Susan , Nakazibwe Esther , Akello Florence , Kiwanuka Samuel , Kiwudhu Fred , Sewankambo Moses , Nsubuga Denis , Kizindo Robert , Staedke Sarah G , Cose Stephen , Webb Emily , Elliott Alison M 
Published: February 2021

IntroductionDrivers of lower vaccine efficacy and impaired vaccine-specific immune responses in low-income versus high-income countries, and in rural compared with urban settings, are not fully elucidated. Repeated exposure to and immunomodulation by parasite infections may be important. We focus onPlasmodium falciparummalaria, aiming to determine whether there are reversible effects of malaria infection on vaccine responses.Methods and analysisWe have designed a randomised, double-blind, placebo-controlled, parallel group trial of intermittent preventive malaria treatment versus placebo, to determine effects on vaccine response outcomes among school-going adolescents (9 to 17 years) from malaria-endemic rural areas of Jinja district (Uganda). Vaccines to be studied comprise BCG vaccine on day ‘zero’; yellow fever, oral typhoid and human papilloma virus vaccines at week 4; and tetanus/diphtheria booster vaccine at week 28. Participants in the intermittent preventive malaria treatment arm will receive dihydroartemisinin/piperaquine (DP) dosed by weight, 1 month apart, prior to the first immunisation, followed by monthly treatment thereafter. We expect to enrol 640 adolescents. Primary outcomes are BCG-specific interferon-γ ELISpot responses 8 weeks after BCG immunisation and for other vaccines, antibody responses to key vaccine antigens at 4 weeks after immunisation. In secondary analyses, we will determine effects of monthly DP treatment (versus placebo) on correlates of protective immunity, on vaccine response waning, on whether there are differential effects on priming versus boosting immunisations, and on malaria infection prevalence. We will also conduct exploratory immunology assays among subsets of participants to further characterise effects of the intervention on vaccine responses.Ethics and disseminationEthics approval has been obtained from relevant Ugandan and UK ethics committees. Results will be shared with Uganda Ministry of Health, relevant district councils, community leaders and study participants. Further dissemination will be done through conference proceedings and publications.Trial registration numberCurrent Controlled Trials identifier:ISRCTN62041885.
Association between early working life patterns, in publicly and privately owned companies, and the course of future sickness absence due to mental disorders: a cohort study in Catalonia (Spain)
Authors: Ayala-Garcia Amaya , Serra Laura , Ubalde-Lopez Monica 
Published: February 2021

ObjectivesTo assess the relationship between early working life patterns, at privately and publicly held companies, and the course of sickness absence (SA) due to mental disorders.MethodsCohort study of workers aged 18–28 years, affiliated with the Spanish social security system, living in Catalonia, who had at least one episode of SA due to mental disorders between 2012 and 2014. Individual prior working life trajectories were reconstructed through sequence analysis. Optimal matching analysis was performed to identify early working life patterns by clustering similar individual trajectories. SA trajectories were identified using latent class growth modelling analysis. Finally, the relationship between early working life patterns and subsequent SA trajectories was assessed via multinomial logistic regression models.ResultsAmong both men and women, four labour market participation (LMP) patterns were identified: stable permanent employment (reference group), increasing permanent employment, fluctuating employment and delayed employment. Among women, an increasing permanent employment pattern in early working life was related to a decrease of accumulated SA days over time (adjusted OR (aOR) 2.08; 95% CI 1.18 to 3.66). In men, we observed a trend towards a middle stable accumulation of SA days in those with fluctuating employment (aOR 1.25, 95% CI 0.57 to 2.74) or delayed employment (aOR 1.79; 95% CI 0.59 to 5.41). In both men and women, an early working life in big companies was related to a more favourable SA trajectory.ConclusionsEarly LMP patterns characterised by an increasing stability—decreased number of transitions between temporary contracts and lack of social security coverage towards permanent contracts—were related to a better future SA course due to mental diagnosis.
Longitudinal analysis of growth trajectories in young children of Chinese-born immigrant mothers compared with Australian-born mothers living in Victoria, Australia
Authors: Bolton Kristy A , Kremer Peter , Laws Rachel , Campbell Karen J , Zheng Miaobing 
Published: February 2021

BackgroundChinese immigrants are the third largest immigrant group in Australia. Little is known about growth trajectories of their offspring when moving to a Western country. The aim was to describe the growth trajectories between birth to 3.5 years in children of Chinese-born immigrant mothers compared with Australian-born mothers living in Victoria, Australia.MethodsTen nurse measured weights and lengths from birth to 3.5 years were used to examine growth trajectory using linear spline multilevel models. Five knot points were identified at visit 2 (0.5 months), visit 4 (2 months), visit 5 (4.5 months), visit 8 (18 months) and visit 9 (25 months).ResultsEthnic disparities in growth trajectories between these two groups were revealed in models adjusted for birth weight, sex and level of socioeconomic disadvantage. Children of Chinese-born compared with Australian-born mothers revealed different growth rates and significant differences in predicted mean body mass index Z score (zBMI) at all time points from birth to 44 months, except for 12 months. Specifically, when compared with children of Australian-born mothers, children of Chinese-born mothers started with lower predicted zBMI from birth until 0.5 months, had a higher zBMI from 1 to 8 months and a lower zBMI from 12 to 44 months. Early and sharp acceleration of growth was also observed for children of Chinese-born mothers (0.5–2 months) when compared with children of Australian-born mothers (2–18 months).ConclusionDifferences in growth trajectories exist between young children of Chinese-born and Australian-born mothers. Better understanding of these ethnically patterned growth trajectories is important for identifying key opportunities to promote healthy growth in early life.