bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement of Step Responses of Flowrate in a Pipe Using a Kalman-Filtering Laminar Flowmeter
Authors: Sanada Kazushi 
Published: December 2021

Abstract
The aim of our research project is to develop a Kalman filter system which estimates unsteady flowrate of a pipe using a laminar flowmeter. In this study, incompressible flow is assumed as working fluid. When the flow becomes turbulent, it is difficult to establish flow model for turbulent friction. In this study, a laminar flowmeter is constructed in which thirty-two narrow pipes of 1mm in inner diameter are bundled and inserted in main flow path. When fluid flow in the narrow pipe is laminar flow, the Kalman filter theory can be applied to the flow of the narrow pipe. Kalman filter is applied to one of narrow pipes of laminar flowmeter. Both upstream and downstream pressure signals of the targeted narrow pipe are input to the Kalman filter. Midpoint pressure measured by a pressure sensor is compared with midpoint pressure signal which is estimated by the Kalman filter. When flow is laminar flow or the system has linear characteristics, an error signal between estimated pressure and measured pressure decreases according to Kalman filter principle. As a result, because the state variables of the Kalman filter converge to real variables, unsteady flowrate is estimated from the state variables of the Kalman filter. Experimental calibration of the Kalman-filtering laminar flowmeter under steady-state flow condition has been performed. In this study, experiments of step response of flowrate in a pipe are conducted by constructing an experimental circuit using solenoid valves. The purpose of experiment is confirmation of a response time of the Kalman-filtering laminar flowmeter. As a result of experiments, it was shown that the response time is 0.05s.
Numerical Study of a Weight-Adjustable Buoy for Efficient Wave Energy Conversion
Authors: Tian Hao , Zhou Boyang , Zhang Zengmeng , Gong Yongjun 
Published: December 2021

Abstract
Heaving motion of ocean wave is a promising renewable energy source but challenging to capture with consistent conversion efficiencies. Main issue of the varying energy extraction efficiency of wave energy converters (WEC’s) is primarily caused by the variation of incident wave frequency and amplitude. Traditional design of the WEC has to account for the extreme sea conditions, leaving the WEC to work at suboptimal regions for most of the time. Due to the loss characteristics of the fluid power components, the performance and efficiency drop rapidly when moved away from the optimal working condition. In order to improve the efficiency of WEC, the buoy needs to operate at maximum amplitude most of the time. To do so, a new buoy structure based on actively controlled fluid-air ratio is proposed. Contrast to the traditional buoy for WEC’s, which has fixed density and weight, the proposed structure is capable of weight manipulation, resulting adjustable system natural frequency. MATLAB/Simulink simulation analysis is carried out to verify the feasibility of adjusting the gas-liquid ratio inside the buoy with a water hydraulic system. To resonate with the unknown incident wave, maximum power point tracking (MPPT) algorithm is proposed to control the buoy mass with trial steps for maximizing the resonating amplitude of the buoy. Initial simulation results have shown that the proposed system is capable of adjusting the natural frequency and the MPPT algorithm can increase the amplitude of the buoy motion.
Incorporating Valve Switching Losses Into a Static Optimal Control Algorithm for the Hybrid Hydraulic-Electric Architecture (HHEA)
Authors: Khandekar Aditya , Wills Jackson , Wang Meng (Rachel) , Li Perry Y. 
Published: December 2021

Abstract
The Hybrid Hydraulic-Electric Architecture (HHEA) has, in recent years, been proposed as an energy efficient alternative to conventional load-sensing architectures in mobile machines such as excavators and wheel-loaders. HHEA leverages the advantages of hydraulic power and electric power to eliminate throttling valves while also improving the energy and control performance of the system. The architecture utilizes a set of common pressure rails to provide a majority of power and and a small electric motor driven pump to modulate this power to meet the exact demand. Previous work has developed a computationally efficient Lagrange Multiplier approach for determining the optimal pressure rail selections that minimizes the energy losses in the system. The static model used considers only the energy use for each pressure rail selection but not the losses associated with the valves during the transition. This paper presents an approach to include the switching losses in the model and in the optimization procedure. To capture the switching losses, switching events between different rails and at various input and output flow rates were simulated with consideration of valve spool dynamics. A parameterized model that summarizes the losses is then obtained, allowing switching losses to be added to the previous energy analysis. The performance of the switching loss model was compared with reference data obtained from a high-fidelity simulation model. To incorporate the switching losses into optimal control algorithm, an efficient dynamic programming approach that prevents frequent switching is adopted in place of the Lagrange multiplier approach. The overall effect of switching losses on the energy consumption and optimal control decisions is presented. In general, switching losses contribute to about 9–10% of input energy.
Prediction, Control and Energy Analyses of Hydraulic Transformer Based Heave Compensator
Authors: Yu Huan , Fang Jinhui , Wei Jianhua , Li Shizhen , Zhang Hangjun 
Published: December 2021

Abstract
Heave compensators are widely used in offshore equipments to decouple the load motion from the wave induced ship motion. Hydraulic transformer based heave compensator (HTHC) can better compensate the ship’s heave in comparison with passive heave compensators (PHC) under changing sea conditions, meanwhile the accumulators’ volume is decreased significantly. Here in this paper, some further discussions about HTHC are given on the aspects of prediction, controller design and energy saving through simulation. Results turn out that heave prediction based on sliding mode observer is better than the Luenberger observer based one; chattering can be reduced through back-stepping method. The controller is robust when the load is perturbed by uncertain forces, and energy consumption of HTHC is about 56% of the one in an equal-sized hybrid active heave compensator (HAHC) meanwhile its total installed power can be reduced by 70%.
The Effect of Slotted Hole on Minimum Oil Film Thickness of Piston in Radial Piston Hydraulic Motor
Authors: Zhang Xiaolong , Zhang Junhui , Xu Bing , Yang Zhixian , Zhao Qi , Zhang Hongjuan 
Published: December 2021

Abstract
The cam-lobe radial-piston hydraulic motor, a multistroke low-speed high-torque motor, is widely used in large rotating machines such as winches, shield machines, and shredders, etc. There is a slotted hole on its pistons to reduce inertial force, which can simultaneously affect piston deformation. Unfortunately, piston deformation will also have an obvious impact on the oil film characteristics of the interface between pistons and cam rollers. Accordingly, in this paper, a coupled model, which combines the unsteady elastohydrodynamic lubrication model and a structural mechanics model, is established. Based on the model, the effect of the slotted hole on the minimum oil film thickness is analyzed through the dynamic simulation. The simulation results show that the slotted hole alters the oil film shape and pressure distribution. As a result, the minimum oil film thickness increases. This study could provide valuable guidance for further optimizing the piston of radial piston hydraulic motor.
Investigating the Filtration Characteristics of Direct Driven Hydraulics
Authors: Han Xu , Välimaa Jussi , Orifjonov Abdullokh , Padovani Damiano , Minav Tatiana 
Published: December 2021

Abstract
Direct driven hydraulics (DDH) is receiving increasing attention due to its advantages such as high energy efficiency, easy maintenance, and compactness. However, its oil contamination management has not been surveyed in detail, whereas uncontrolled oil contamination might result in extra maintenance efforts or even downtime. Therefore, this research paper analyzes the oil filtration in direct driven hydraulics through modeling and simulation to predict the filtration effects and support the filtration design. Firstly, model blocks of the filtration characteristics are built to be added to the basic DDH dynamic model. The model can hereby include the coupling effects between fluid degradation and component wear, the filtering process, and the time-varying filter performance. Secondly, the proposed model is applied to a DDH that incorporates filtration and simulated under a duty cycle for 960 hours. The DDH efficiency and control performance when considering the contaminant are revealed. Thirdly, the results are compared between different filter selections and a filtration solution is finally proposed. In conclusion, this paper illustrates the filtration effects on the efficiency, control performance, and oil contaminant level of DDH by simulation, which can hereby support the design of the DDH filtration solution. According to the simulations, the filtered DDH resulted in 96% degradation of the pump’s volumetric efficiency after 960-hour running compared to 92% when not using any filters. The extra pressure drop introduced by the filter is below 2 bar, suggesting that the introduction of a filter with 6 μm filtration level is beneficial.
Coaching Through a “Gender Lens” May Reveal Myths That Hinder Female Athletes: A Multistudy Investigation
Authors: Gosai Jyoti , Jowett Sophia , Rhind Daniel J.A. 
Published: December 2021

The purpose of this multistudy paper was to explore (a) the coaching behaviors of male coaches when coaching either male or female teams through a systematic observation (Study 1) and (b) male and female coaches’ reasons for employing certain behaviors and practices when coaching female athletes through semistructured interviews (Study 2). Collectively, the findings of these two studies highlighted that coaches, either consciously or unconsciously, use a “gender lens” to coach their athletes. Study 1 findings showed that male coaches organize practice sessions (e.g., longer sessions for female than male athletes) and manifest coaching behaviors (e.g., more reinforcement for female than male athletes) that are different depending on whether they coach teams that comprise male or female athletes. Study 2 findings revealed gender biases in the approaches and styles coaches employed to coach their female and male athletes, suggesting that such methods could be limiting female athletes’ physical, social-emotional, and psychological development. This multistudy paper discusses how coaches’ good intentions to coach effectively can fall short and into a trap of gender stereotypes, leading to coaching the gender of the athletes as opposed to coaching each one athlete as an individual. The implications of these findings for practice are discussed.
Speed Improves With Eccentric Hamstring Training in Athletes of Different Maturity Status
Authors: Hammami Raouf , Gene-Morales Javier , Nebigh Ammar , Rebai Haithem , Colado Juan C. 
Published: December 2021

Purpose: To investigate the effects of an eccentric hamstring strength training program (EHT) on sprint performance (10-, 20-, and 30-m sprint times) and change of direction speed (4 × 5-m shuttle run and T-Half test) in male European handball athletes at 2 maturity statuses (prepeak and postpeak height velocity [PHV]). Methods: Forty-five participants (12.68 [1.58] y) were divided into pre-PHV and post-PHV and randomly allocated to a control or intervention group, which performed a guided 2 day per week 6-week EHT of 5 exercises. A mixed-model (within- and between-factor) analysis of variance was conducted. Results: A significant effect (P < .05) of the interaction time × maturity × training was observed in the T-Half, 10, and 30 m tests. Both intervention groups significantly improved in all the tests, except in the 20 m sprint and the post-PHV in the 10 m sprint. Improvements ranged between 0.93% and 5.74% (effect size: 0.07–0.79). Both control groups yielded no improvements in almost all the tests. The improvements of both groups undergoing the intervention (pre-PHV and post-PHV) were not significantly different (only a tendency in the 10 m sprint). Conclusion: An EHT program combined with European-handball training improve change of direction and sprint performance in pre-PHV and post-PHV male players. Professionals training European handball and similar team-sport athletes should consider including EHT regardless of athlete’s maturity.
Child nutritional status as screening tool for identifying undernourished mothers: an observational study of mother–child dyads in Mogadishu, Somalia, from November 2019 to March 2020
Authors: Zacks Rachael , Ververs Mija , Hwang Cindy , Mahdi Adan , Leidman Eva 
Published: December 2021

BackgroundActive screening of only pregnant and lactating mothers (PLMs) excludes other mothers of reproductive age susceptible to undernutrition. Our analysis evaluated if mothers presenting with wasted children were more likely to be undernourished themselves.MethodsThe observational study enrolled mother and child dyads presenting to an outpatient facility in Mogadishu, Somalia, between November 2019 and March 2020. Trained nurses recorded lower extremity oedema for children aged 6–59 months, parity and gestational status for women aged 19–50 years and age, access to care, height/length, mid-upper arm circumference (MUAC) and weight for both. Weight-for-height z-score (WHZ) for children and body mass index (BMI) for mothers were calculated using standard procedures. Wasting was defined as WHZ <−2, MUAC <12.5 cm and/or presence of oedema for children. Undernutrition was defined as MUAC <23 cm for PLMs and BMI <18.5 kg/m2for neither pregnant nor lactating mothers (non-PLMs). Four multivariable linear regression models were fit to evaluate maternal anthropometric indicators (BMI or MUAC) given child anthropometric indicators (MUAC or WHZ), adjusting for maternal age, parity and gestational status.ResultsA total of 93.6% (2142/2288) of enrolled dyads met inclusion criteria. Wasting was observed among 57.5% of children; 20.2% of pregnant mothers, 20.0% of lactating mothers and 7.95% of non-PLMs were undernourished. Models suggest significant, positive associations between child and maternal anthropometrics; a one-unit increase in WHZ and a 1 cm increase in child MUAC were associated with 0.22 kg/m2(95% CI 0.22 to 0.24) and 0.19 kg/m2(95% CI 0.16 to 0.21) increases in maternal BMI, respectively, and 0.20 cm (95% CI 0.18 to 0.22) and 0.24 cm (95% CI 0.23 to 0.25) increases in maternal MUAC, respectively. Adjusted R2values were low (range 0.06–0.10).ConclusionsUndernutrition among non-PLMs illustrates the importance of expanding screening. However, while significant, the strength of association between mother and child anthropometrics does not support child nutritional status as a screening tool for identifying at-risk mothers.
Risk assessment of metabolic syndrome prevalence involving sedentary occupations and socioeconomic status
Authors: Chen Ming-Shu , Chiu Chi-Hao , Chen Shih-Hsin 
Published: December 2021

ObjectivesTo determine whether occupation type, distinguished by socioeconomic status (SES) and sedentary status, is associated with metabolic syndrome (MetS) risk.MethodsWe analysed two data sets covering 73 506 individuals. MetS was identified according to the criteria of the modified Adult Treatment Panel III. Eight occupational categories were considered: professionals, technical workers, managers, salespeople, service staff, administrative staff, manual labourers and taxi drivers; occupations were grouped into non-sedentary; sedentary, high-SES; and sedentary, non-high-SES occupations. A multiple logistic regression was used to determine significant risk factors for MetS in three age-stratified subgroups. R software for Windows (V.3.5.1) was used for all statistical analyses.ResultsMetS prevalence increased with age. Among participants aged ≤40 years, where MetS prevalence was low at 6.23%, having a non-sedentary occupation reduced MetS risk (OR=0.88, p<0.0295). Among participants aged >60 years, having a sedentary, high-SES occupation significantly increased (OR=1.39, p<0.0247) MetS risk.ConclusionsThe influence of occupation type on MetS risk differs among age groups. Non-sedentary occupations and sedentary, high-SES occupations decrease and increase MetS risk, respectively, among younger and older adults, respectively. Authorities should focus on individuals in sedentary, high-SES occupations.
Structural equation model of physical activity in Turkish schoolchildren: an application of the integrated behavioural model
Authors: Mirzayi Chloe , Ferris Emily , Ozcebe Hilal , Swierad Ewelina , Arslan Umut , Ünlü Hande , Araz Ozgur , Yardim Mahmut Saadi , Üner Sarp , Bilir Nazmi , Huang Terry T 
Published: December 2021

ObjectivesChildhood obesity is increasingly prevalent in the developing world including Turkey. This study examined constructs of the integrated behavioural model associated with physical activity in a sample of schoolchildren in Ankara, Turkey using structural equation modelling.DesignCross-sectional survey by probability sampling.SettingFifteen schools of different socioeconomic strata in Ankara, Turkey with grade 4 students.Participants2066 (969 girls and 1097 boys) grade 4 schoolchildren and their parents selected using a probability-based sampling frame.Primary outcome measuresThree primary outcomes were used: moderate-to-vigorous physical activity, team sport participation, sedentary behaviour.ResultsData were collected from 2066 fourth-grade children from schools of three socioeconomic strata. Missing data were imputed using multiple imputation. To examine the integrated behavioural model, a structural equation model containing latent constructs for physical activity outcome expectancies, self-efficacy, home environment and social norms were fitted with the three outcomes above. Adequate model fit was achieved in the structural equation model (χ2=1821.97, df=872, p<0.001, Comparative Fit Index=0.91, Tucker Lewis Index=0.91, root mean square error of approximation=0.02, standardised root mean square residual=0.04). All scale items were significantly associated with their respective latent constructs (all p<0.001). Several significant pathways between latent constructs and outcomes of interest were observed (p<0.05). Self-efficacy was positively associated with moderate-to-vigorous physical activity (p<0.001) and team sport participation (p<0.001) and negatively associated with sedentary behaviour (p<0.001). Negative outcome expectancies were negatively associated with moderate-to-vigorous physical activity (p<0.01) and sedentary behaviour (p<0.01) while positive outcome expectancies were positively associated with team sport behaviour (p<0.001) and negatively associated with sedentary behaviour (p<0.05). Home support was positively associated with moderate-to-vigorous physical activity (p<0.01) and team sport participation (p<0.05). Finally, physical activity social norms were negatively associated with sedentary behaviour only (p<0.05).ConclusionsThis study supported the extension to Turkish children of the integrated behavioural model in relation to physical activity behaviours. Results illustrate multiple targets for interventions to increase physical activity.
Population-based study of the association between asthma and exogenous female sex hormone use
Authors: Jung Won Jai , Lee Sang Yeub , Choi Sue In , Kim Byung-Keun , Lee Eun Joo , Choi Jimi 
Published: December 2021

ObjectivesSeveral studies have suggested the influence of exogenous hormones on asthma, but the results are still conflicting. Moreover, there has been little associated research on Asian population. This study aimed to assess the association between use of exogenous female sex hormones and asthma in Korean women.DesignKorea National Health and Nutrition Examination Survey (KNHANES) is a nationwide programme to assess national health and nutritional status in Korea. A population-based study was conducted to analyse the relationship between self-reported asthma and exogenous hormones using the KNHANES between 2007 and 2012.ParticipantsThe study sample included 6874 premenopausal and 4912 postmenopausal women aged 30–65.Outcome measuresKNHANES data comprised health interviews and physical examinations. Questionnaires regarding asthma, reproductive factors and exogenous hormones were included.ResultsAmong postmenopausal women, 3.4% reported doctor-diagnosed asthma. Hormone replacement therapy (HRT) was associated with increased odds of doctor-diagnosed asthma (OR 1.56; 95% CI 1.04 to 2.35), while the association between HRT and wheeze in the last 1 year was not significant (OR 1.37; 95% CI 0.95 to 1.96). In premenopausal women, the prevalence of asthma was 2.3%. Use of oral contraceptives (OCs) was associated with an increased odds of doctor-diagnosed asthma (OR 1.67; 95% CI 1.01 to 2.76) and wheeze in the last 1 year (OR 1.88; 95% CI 1.31 to 2.69). These associations were dominant among non-obese women (body mass index <25 kg/m2; OR 2.36; 95% CI 1.34 to 4.17 for asthma and OR 2.15; 95% CI 1.43 to 3.23 for wheeze).ConclusionsHRT and OCs were associated with increased asthma in postmenopausal and premenopausal women, respectively. The association between OC use and asthma was strong in non-obese premenopausal women.
Prevalence, classification, risk factors and outcome impact of delirium in patients with COVID-19: a meta-analysis protocol for systematic review
Authors: Lou Baohui , Guo Jingfei , Liu Yue , Xiong Chao , Shi Jia , Zhou Chenghui 
Published: December 2021

IntroductionPrevious studies have shown mixed results that delirium may result in a high risk of adverse clinical outcomes in patients with COVID-19. The aim of this meta-analysis is to summarise the evidence of prevalence, classification, risk factors and outcomes impact of delirium in adult patients with COVID-19.MethodsA systematic search will be performed in PubMed, EMBase, ISI Knowledge via Web of Science and preprint databases (MedRxiv and BioRxiv) (from inception until June 2021) to identify all cohort studies concerning delirium in adult patients with COVID-19. The primary outcome will be the prevalence of delirium with different classifications (hyperactive, hypoactive or mixed type). The secondary outcomes will include the association of risk factors and the association with all-cause mortality during hospitalisation. Univariable or multivariable meta-regression and subgroup analyses will be conducted for the study design and patient characteristics. Sensitivity analyses were used to assess the robustness of our results by removing each included study at one time to obtain and evaluate the remaining overall estimates of primary and secondary outcomes.Ethics and disseminationEthical approval is not an essential element for the systematic review protocol in accordance with the Institutional Review Board /Independent Ethics Committee of Beijing Hospital. This meta-analysis will be disseminated through a peer-reviewed journal for publication.PROSPERO registration numberCRD42020224871.