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Instability of wall jet produced by twodimensional inclined jet
Gentaro Takeda,Yu Ito,Kenji Yamashiro,Hideyuki Takahashi,Nao Ninomiya,Yuya Uranaka,Jurai Fujikura 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.1
This paper focuses on a two-dimensional jet that impinges on a sloping wall surface. It investigates the vibration behavior and wall jet development morphology during wall impingement. Flow visualization experiments of jets impinging on a plate arranged vertically and at an angle of 65° were conducted. In the range where the distance between the jet nozzle and the plate is from the near field to the transition region, the vibration form of the impinging jet changes sensitively. The range of the distance between the jet nozzle and the impinged plate where no shear vortex forms on the wall surface is expanded by the inclined impinging jet. On the upward side, where the fluid easily flows due to the inclined impinging jet, an increase in the vibration frequency was also confirmed as the wall jet velocity increased. PIV measurements showed that wall jet separation after inclined impinging was delayed in comparison with vertical impinging, and a stable wall jet was formed.
Gentaro Takeda,Yu Ito,Kenji Yamashiro,Hideyuki Takahashi,Nao Ninomiya,Jurai Fujikura,Shun Akutsu 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.11
This paper focuses on the development formation of two-dimensional impinging jets. Since it is known that vibration of a two-dimensional jet injected from a gas wiping nozzle affects the morphology of the coating surface, control of the jet properties is a very important issue. In this paper, jets with different initial velocity distributions were created, depending on the internal shape of the nozzle, and the behavior of the impinging two-dimensional jet in the transition region was evaluated by flow visualization. One nozzle (contoured nozzle) had a curvilinearly contracting shape as the flow approached the nozzle injection port, and the other (straight nozzle) was provided with a parallel part having a length 17 times the width of the nozzle gap in the flow path of the nozzle injection port. The jets ejected from these nozzles differed significantly in the velocity profile and in the vortex formation at the edges of the jet before impingement. There were also differences in the wall jet thickness and jet velocity attenuation of the wall jet. The difference in the wall jet characteristics due to the nozzle type is remarkable in impingement at the beginning of the transition region, but the difference decreases with the impinged wall distance where collapse of the large-scale vortex is seen even in the transition region.
A distinct functional distribution of α and γ motoneurons in the rat trigeminal motor nucleus
Morita-Isogai, Yukako,Sato, Hajime,Saito, Mitsuru,Kuramoto, Eriko,Yin, Dong Xu,Kaneko, Takeshi,Yamashiro, Takashi,Takada, Kenji,Oh, Seog Bae,Toyoda, Hiroki,Kang, Youngnam Springer-Verlag 2017 BRAIN STRUCTURE AND FUNCTION Vol.222 No.7
<P>Gamma-motoneurons (gamma MNs) play a crucial role in regulating isometric muscle contraction. The slow jaw-closing during mastication is one of the most functional isometric contractions, which is developed by the rank-order recruitment of alpha-motoneurons (alpha MNs) in a manner that reflects the size distribution of alpha MNs. In a mouse spinal motor nucleus, there are two populations of small and large MNs; the former was identified as a population of gamma MNs based on the positive expression of the transcription factor estrogen-related receptor 3 (Err3) and negative expression of the neuronal DNA-binding protein NeuN, and the latter as that of alpha MNs based on the opposite pattern of immunoreactivity. However, the differential identification of alpha MNs and gamma MNs in the trigeminal motor nucleus (TMN) remains an assumption based on the size of cell bodies that were retrogradely stained with HRP. We here examined the size distributions of alpha MNs and gamma MNs in the dorsolateral TMN (dl-TMN) by performing immunohistochemistry using anti-Err3 and anti-NeuN antibodies. The dl-TMN was identified by immunopositivity for vesicular glutamate transporter-1. Immunostaining for choline acetyltransferase and Err3/NeuN revealed that the dl-TMN is composed of 65% alpha MNs and 35% gamma MNs. The size distribution of alpha MNs was bimodal, while that of gamma MNs was almost the same as that of the population of small alpha MNs , suggesting the presence of alpha MNs as small as gamma MNs. Consistent with the size concept of motor units, the presence of smaller jaw-closing alpha MNs was coherent with the inclusion of jaw-closing muscle fibers with smaller diameters compared to limb muscle fibers.</P>