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Barratt, Dylan,Lee, Jaehyoung,Atkins, Michael D.,Song, Seung Jin,Kim, Tongbeum Elsevier 2018 Experimental thermal and fluid science Vol.99 No.-
<P><B>Abstract</B></P> <P>We experimentally examine the impingement of a fully turbulent round jet (with diameter <I>D<SUB>j</SUB> </I>) on a long circular cylinder (with diameter <I>D</I>) in the crossflow plane coinciding with the jet axis for <I>D</I>/<I>D<SUB>j</SUB> </I> = 2.5 and <I>Re<SUB>Dj</SUB> </I> = 20,000. Particular focus is placed on the kinematics of boundary layer transition that occurs and subsequently leads to a second thermal peak on the cylinder surface downstream of the primary thermal peak near the stagnation point when placed inside the jet’s potential core. To this end, spectral analyses of wall shear stress data and time-resolved velocity data within both laminar and turbulent boundary layers have been performed. The present study demonstrates that the root mean square (rms) fluctuation of the stream-wise velocity component increases along both boundary layers due to the propagation of external perturbations from coherent structures that are shed from the jet exit, which incites the transition of the laminar boundary layer. The transition causes the local heat transfer elevation that interrupts the monotonic decrease from the primary thermal peak whereas it plays no direct part in forming the second thermal peak. Instead, the second thermal peak occurs at a delayed downstream azimuth angle from the transition where the rms velocity fluctuations of the boundary layer flow reach their peak at the dominant frequency, equivalent to that of the coherent structures of the jet.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The propagation of perturbations from the jet incites the transition. </LI> <LI> The rms fluctuation of the boundary layer flow increases. </LI> <LI> The transition plays no direct part in forming the second thermal peak. </LI> <LI> The second thermal peak occurs at a delayed downstream azimuth angle from the transition. </LI> <LI> The rms fluctuation of the boundary layer flow reaches a peak causing the second thermal peak. </LI> </UL> </P>
( Taylor Braden ),( Madison Burtch ),( Samantha Mott ),( Alexandria Pyle ),( Lee Atkins ),( Heather Braden ) 대한신경치료학회 2021 신경치료 Vol.25 No.1
Purpose Assessing functional mobility is an important aspect of determining fall risk in the growing population of assisted living. Little is known about the sit-to-walk (STW) transition, especially what characteristics correlate with the duration it takes to perform a STW. Methods In this cross-sectional, exploratory study, 45 assisted living residents were evaluated for baseline measures: history of falls, assistive device (AD), lower-extremity strength, and balance (Tinetti POMA). The residents were then timed performing a STW, and, from these durations, were stratified into fast and slow groups. Statistical analysis was performed to determine relationships between the two duration groups and the baseline measures. Results Participants who had experienced a fall were significantly more likely to use an assistive device (p = 0.001). The use of an AD had a moderate negative correlation with composite strength (r = -0.428, p = 0.003). Duration of STW had a weak negative correlation with composite strength (r = -0.299, p = 0.046) and a moderate correlation with use of AD (r = 0.419, p = 0.004). Those with a faster duration of STW had significantly better balance (p = 0.027). Conclusion These correlations support the need for healthcare professionals to address the use of adaptive equipment and physical training when evaluating functional mobility in assisted living residents. Providing appropriate equipment and improving overall strength in these individuals can help reduce their risk of falls. Individuals in assisted living facilities can be assessed similar to other geriatric populations, with special consideration on functional tasks and measures.