Suchergebnisse

Unmanned Aerial Vehicles, UAVs, gained an important role in modern military and civilian applications. Developments in UAVs technology improve its performance and maneuverability with acceptable cost. Elliptic airfoil had been widely used in the development of Rotor/Wing subsonic aircraft. The present work aims to investigate the effect of various elliptic airfoil parameters, such as Reynolds number, angle of attack and airfoil thickness, on aerodynamic behavior using two-dimensional computational study. The computational results were validated by experimental results. Angles of attack was evaluated from 0° to 18° in order to analyze aerodynamic characteristics up to stall condition, while Reynolds number was evaluated at values of 1×10âµ, 3×105, 2×106, and 8×106, to cover the range of rotary and fixed wing flight conditions. Thickness ratio was ranged from 5% to 25% to include the UAVs airfoil thicknesses so that choice best thickness gets max lift to drag ratio. In addition, the thicknesses location was evaluated for a range of 30% to 70% to get suitable location gets max left to drag ratio. The ANSYS-Fluent software was used with Spalart-Allmaras turbulence model, and found that the maximum lift to drag ratio which improve the UAV capability in this study is at Re=2×106, angle of attack at 8°, max thickness ratio of (0.1chord) located at (0.3chord).

Rationale: Body composition changes throughout life may explain the inconsistent associations reported between body mass index and lung function in children. Objectives: To assess the associations of body weight and composition trajectories from 7 to 15 years with lung function at 15 years and lung function growth between 8 and 15 years. Methods: Sex-specific body mass index, lean body mass index, and fat mass index trajectories were developed using Group-Based Trajectory Modeling on data collected at least twice between 7 and 15 years from 6,964 children (49% boys) in the UK Avon Longitudinal Study of Parents and Children birth cohort. Associations of these trajectories with post-bronchodilation lung function parameters at 15 years and with lung function growth rates from 8 to 15 years were assessed using multivariable linear regression models, stratified by sex, in a subgroup with lung function data (n = 3,575). Measurements and Main Results: For all body mass measures we identified parallel trajectories that increased with age. There was no consistent evidence of an association between the body mass index trajectories and lung function measures. Higher lean body mass index trajectories were associated with higher levels and growth rates of FVC, FEV1, and forced expiratory flow, midexpiratory phase in both sexes (e.g., boys in the highest lean body mass index trajectory had on average a 0.62 L [95% confidence interval, 0.44-0.79; P trend < 0.0001] higher FVC at 15 yr than boys in the lowest trajectory). Increasing fat mass index trajectories were associated with lower levels and growth rates of FEV1 and forced expiratory flow, midexpiratory phase only in boys and lower levels of FEV1/FVC in both sexes. Conclusions: Higher lean body mass during childhood and adolescence is consistently associated with higher lung function at 15 years in both sexes, whereas higher fat mass is associated with lower levels of only some lung function parameters. ; The present analyses are part of the ALEC (Ageing Lungs in European Cohorts) Study (www.alecstudy.org), which has received funding from the European Union's Horizon 2020 research and innovation program under grant agreement No. 633212. The content of this article reflects only the authors' views, and the European Commission is not liable for any use that may be made of the information contained therein. The UK Medical Research Council and Wellcome Trust (grant reference number: 102215/2/13/2) and the University of Bristol provide core support for ALSPAC. A comprehensive list of grant funding is available on the ALSPAC website (http://www.bristol.ac.uk/alspac/external/documents/grant-acknowledgements.pdf). Specifically, grants from Wellcome Trust and Medical Research Council (076467/Z/05/Z and G0401540/73080) supported the collection of body composition and lung function data at 15 years. E.F. is supported by a Marie Skłodowska-Curie Individual Fellowship (H2020-MSCA-IF-2015; proposal number 704268). C.R. is the recipient of a European Respiratory Society Fellowship (RESPIRE3-201703-00127, under H2020—Marie Skłodowska-Curie Actions COFUND).

Background: Although physical activity has many known health benefits, its association with lung function in childhood/adolescence remains unclear. We examined the association of physical-activity trajectories between 11 and 15 years with lung function at 15 years in 2266 adolescents. Methods: A population-based cohort of 14 305 singleton births alive at 1 year was recruited in the UK population-based Avon Longitudinal Study of Parents and Children cohort. Physical activity (counts/minute and moderate-to-vigorous physical activity) was assessed for 7 days using an accelerometer at 11, 13 and 15 years. We identified sex-specific physical-activity trajectories applying K-means for longitudinal data in children with at least two accelerometer measurements (n = 3584). We then estimated the sex-specific associations of these trajectories with post-bronchodilation lung-function parameters using multivariable linear-regression models (n = 2266, 45% boys). Results: Fewer than 7% of participants met the WHO physical-activity recommendations (i.e. daily average of at least 60 minutes of moderate-to-vigorous physical activity). Boys were substantially more active than girls. In both sexes, we identified three distinct physical-activity trajectories ('low': 39.8% boys, 45.8% girls; 'moderate': 42.9% boys, 41.4% girls; and 'high' physical activity: 17.3% boys, 12.8% girls). Girls in the moderate and high physical-activity trajectories had 0.11 L [95% confidence interval (CI): 0.04-0.19] and 0.15 L (95% CI: 0.03-0.26) higher forced vital capacity than their less-active peers. No association was observed in boys. Conclusions: Higher childhood physical activity relates to higher lung-function levels in adolescent girls. A better understanding of the mechanisms underlying this association should be pursued. ; The present analyses are part of the Ageing Lungs in European Cohorts (ALEC) Study (www.alecstudy.org), which has received funding from the European Union's Horizon 2020 research and innovation programme (grant agreement no. 633212). The UK Medical Research Council, the Wellcome Trust (grant: 102215/2/13/2) and the University of Bristol provide core support for the Avon Longitudinal Study of Parents and Children (ALSPAC). Elaine Fuertes is supported by a Marie Skłodowska-Curie Individual Fellowship (H2020-MSCA-IF-2015; proposal number 704268). Célina Roda is the recipient of a European Respiratory Society Fellowship (RESPIRE3-201703–00127, under H2020—Marie Skłodowska-Curie actions COFUND). These funders did not have any role in the design and conduct of the study; collection, management, analysis and interpretation of the data; preparation, review or approval of the manuscript; and decision to submit the manuscript for publication.

Background: Residing in greener areas is increasingly linked to beneficial health outcomes, but little is known about its effect on respiratory health. Objective: We examined associations between residential greenness and nearby green spaces with lung function up to 24 years in the UK Avon Longitudinal Study of Parents and Children (ALSPAC) birth cohort. Methods: Lung function was measured by spirometry at eight, 15 and 24 years of age. Greenness levels within circular buffers (100-1000 m) around the birth, eight-, 15- and 24-year home addresses were calculated using the satellite-derived Normalized Difference Vegetation Index and averaged (lifetime greenness). The presence and proportion of green spaces (urban green spaces, forests and agricultural land) within a 300 m buffer was determined. First, associations between repeated greenness and green space variables and repeated lung function parameters were assessed using generalized estimation equations (N = 7094, 47.9% male). Second, associations between lifetime average greenness and lifetime average proportion of green spaces with lung function at 24-years were assessed using linear regression models (N = 1763, 39.6% male). All models were adjusted for individual and environmental covariates. Results: Using repeated greenspace and lung function data at eight, 15 and 24 years, greenness in a 100 m buffer was associated with higher FEV1 and FVC (11.4 ml [2.6, 20.3] and 12.2 ml [1.8, 22.7], respectively, per interquartile range increase), as was the presence of urban green spaces in a 300 m buffer (20.3 ml [-0.1, 40.7] and 23.1 ml [-0.3, 46.5] for FEV1 and FVC, respectively). These associations were independent of air pollution, urbanicity and socio-economic status. Lifetime average greenness within a 100 m buffer and proportion of agricultural land within a 300 m buffer were associated with better lung function at 24 years but adjusting for asthma attenuated these associations. Discussion: This study provides suggestive evidence that children whose homes are in more vegetated places or are in close proximity of green spaces have better lung function up to 24 years of age. ; The present analyses are part of the Ageing Lungs in European Cohorts (ALEC) study (www.alecstudy.org), which has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 633212. Célina Roda is the recipient of a European Respiratory Society Fellowship [RESPIRE3-201703-00127], under H2020 - Marie Skłodowska-Curie actions COFUND]. The funding sources were not involved in the study design, in the collection, analysis and interpretation of data, the writing of the report and in the decision to submit the article for publication.