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variability-patterns
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Obtaining uniform cooling on a hot surface by a novel swinging slot impinging jet
, Article Applied Thermal Engineering ; Volume 150 , 2019 , Pages 781-790 ; 13594311 (ISSN) ; Eghtesad, A ; Afshin, H ; Shafii, M. B ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In this study, a novel 2D laminar Swinging Slot Impinging Jet (SSIJ) on a heated flat surface was investigated using numerical simulation. The impinging jet was introduced to improve the uniform cooling of a hot surface while enhancing the heat transfer rate by disrupting the boundary layer. The impinging jet moves along the target surface similar to the swinging motion of a pendulum. The effects of Reynolds number, dimensionless jet to target distance, maximum angle of swinging, and frequency of jet oscillations were studied, and physics of the new impinging jet were fully discussed. Lastly, optimization was undertaken to search for the optimal variables leading to uniform heat fluxes. A...
Principal component analysis of kinematic patterns variability during sit to stand in people with non-specific chronic low back pain
, Article Journal of Mechanics in Medicine and Biology ; Volume 12, Issue 2 , 2012 ; 02195194 (ISSN) ; Tajali, S ; Negahban, H ; Shaterzadeh, M. J ; Salehi, R ; Narimani, R ; Parnianpour, M ; Sharif University of Technology
2012
Abstract
Sit to stand (STS) task requires variability of all body segments to achieve the stability of the important control variables (i.e., center of mass (CM) and head positions). In this study, the possible differences in the variability patterns of various body segments were investigated between 11 chronic low back pain (LBP) and 12 control subjects during STS task through two types of variability analyses; first by calculating the variability of seven limb angles, CM and head positions across 15 trials and second by principal component analysis (PCA) of seven limb angles. Participants performed the task at 3 postural difficulty levels: rigid surface, open eyes (RO), rigid surface, close eyes...
The effects of postural difficulty conditions on variability of joint kinematic patterns during sit to stand task in normals and patients with non-specific chronic low back pain
, Article 2011 1st Middle East Conference on Biomedical Engineering, MECBME 2011, 21 February 2011 through 24 February 2011, Sharjah ; 2011 , Pages 300-303 ; 9781424470006 (ISBN) ; Negahban, H ; Yazdi, M. J. S ; Salehi, R ; Mehravar, M ; Parnianpour, M ; Sharif University of Technology
2011
Abstract
Sit to stand (STS) is one of the most important activities of daily living that is shown to be affected in low back pain (LBP) patients. It requires a fundamental coordination action among all segments (DOFs) of the body in order to control important performance variables such as body's center of mass (CM) within base of support (BOS). In this study, possible differences in joint coordination and variability patterns between chronic LBP and healthy control subjects were investigated during STS task. Eleven adults with nonspecific chronic LBP and 12 healthy controls were recruited in the study. The participants performed the task in 3 exerimental conditions including: rigid surface, open eyes...