913 research outputs found

    Velocity and Temperature Fields in Circular Jet Expanding from Choked Nozzle into Quiescent Air

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    The Mach number and temperature profiles in jets expanding from convergent and convergent-divergent nozzles are presented for several values of nozzle-exit pressure ratio. The effects of jet temperature, Reynolds number, and humidity on jet spreading are briefly evaluated. The results indicated that the downstream Mach number profiles for a heated jet are slightly narrower than those for a unheated jet, whereas the downstream temperature profiles were unaffected by nozzle temperature change, and that the effects of Reynolds number and humidity were negligible

    Performance characteristics of aircraft cooling ejectors having short cylindrical shrouds

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    The factors affecting the performance of ejector suitable for aircraft cooling are investigated theoretically and experimentally. The investigation covers a range of shroud-to-nozzle diameter ratios from 1.1 to 1.6, of shroud lengths from 0.2 to 2.28 nozzle diameters, of secondary-to-primary weight-flow ratios from 0 to 0.12, and of ambient-to-nozzle pressure ratios from 0.7 to 0.06. The results of a simplified theoretical analysis based on each type of flow are in good agreement with those experimentally obtained

    Investigation at Mach Number 1.91 of Spreading Characteristics of Jet Expanding from Choked Nozzles

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    It is demonstrated that the temperature profiles of jets expanding into a supersonic stream are considerably smaller than the temperature profiles of jets expanding into quiescent air. The effect on the wake of varying afterbody geometry is shown to be small. The gross spreading characteristics of jets expanding from convergent and convergent-divergent nozzles in the base of a body of revolution with various boattail configurations at a Mach number of 1.91 are presented

    A Randomized-Trial Evaluation of the Effect of Whose Future Is It Anyway? on Self-Determination

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    Promoting student involvement in planning has become best practice in the field of transition. Research documents the positive impact of such efforts on greater student involvement. Research also suggests that promoting student involvement results in greater student self-determination, but a causal link has not been established. This study used a randomized- trial, placebo control group design to study the impact of intervention with the Whose Future Is It Anyway? process on self-determination. The authors also examined the impact of intervention on transition knowledge and skills. Results indicated that instruction using the Whose Future Is It Anyway? process resulted in significant, positive differences in self- determination when compared with a placebo-control group and that students who received instruction gained transition knowledge and skills.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

    Violence against primary school children with disabilities in Uganda: a cross-sectional study.

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    BACKGROUND: 150 million children live with disabilities globally, and a recent systematic review found 3 to 4 times the levels of violence versus non-disabled children in high income countries. However, almost nothing is known about violence against disabled children in lower income countries. We aim to explore the prevalence, patterns and risk factors for physical, sexual and emotional violence among disabled children attending primary school in Luwero District, Uganda. METHODS: We performed a secondary analysis of data from the baseline survey of the Good Schools Study. 3706 children and young adolescents aged 11-14 were randomly sampled from 42 primary schools. Descriptive statistics were computed and logistic regression models fitted. RESULTS: 8.8% of boys and 7.6% of girls reported a disability. Levels of violence against both disabled and non-disabled children were extremely high. Disabled girls report slightly more physical (99.1% vs 94.6%, p = 0.010) and considerably more sexual violence (23.6% vs 12.3%, p = 0.002) than non-disabled girls; for disabled and non-disabled boys, levels are not statistically different. The school environment is one of the main venues at which violence is occurring, but patterns differ by sex. Risk factors for violence are similar between disabled and non-disabled students. CONCLUSIONS: In Uganda, disabled girls are at particular risk of violence, notably sexual violence. Schools may be a promising venue for intervention delivery. Further research on the epidemiology and prevention of violence against disabled and non-disabled children in low income countries is urgently needed
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