943 research outputs found
G.E. Stewart Interview - Transcript
No full textG.E. Steward (1906-1979)
G. E. Steward was born near Shreveport, Louisiana and was raised near Longview, Texas. He lost his eyesight when he was twelve and attended the State School for the Blind in Austin. Much of the interview focuses on his relationship with G. P. Bowser, who baptized him in 1931. Steward preached in Abilene, Texas, for three years in the thirties and moved to Memphis in 1936. He served as preacher at the Vance Avenue Church of Christ in Memphis, the Third Ward Church in Houston, and in Oklahoma City before moving to Detroit to the West Side Church. Stewart was a staff writer for the Christian Echo and is the author of Our Pulpit and What the Bible Teaches about Illicit Sex and Homosexuality.
In the interview he talks about his family history and about Bowser. The file consists of information about Steward and includes a term paper and his obituary
Predicting growth rates of interfaces and internal layers in a turbulent boundary layer using a first order jump model
No full textExperimental research is presented on the characteristics of interfaces and internal layers that are present in a turbulent boundary layer (TBL). Both the turbulent non-turbulent interface (T/NT) and internal shear layers are detected in snapshots of the stereo-PIV data. It turns out that the internal layers exhibit similar characteristics compared to the T/NT interface. A theoretical approximation of the large scale boundary layer growth indicates that the correct boundary layer growth can be obtained by employing a modified first order jump model on the conditional statistics. Employing the same framework to the internal shear layers indicates that shear layers tend to move slower in close proximity to the wall, whereas they accelerate when moving away from the wall. Based on previous research it is believed that these internal layers separate large regions of approximately uniform momentum. Hence, boundary entrainment velocities may be interpreted as growth rates of large scale motions in a TBL
Structure and dynamics of turbulent flows over highly permeable walls
No full textHighly porous materials are found in various industrial applications and environmental flows. In previous studies it was found that a turbulent flow along a highly porous wall experiences a higher skin friction as compared to a solid wall with similar surface roughness when the so-called permeability Reynolds number (Re_K) is larger than O(1). The main objective of the present study was to gain understanding of the characteristic structures and auto-generation mechanisms of turbulence for Re_K >> 1. To this purpose the Volume-Averaged Navier-Stokes (VANS) equations were solved in a Direct Numerical Simulation (DNS) of a turbulent flow through a plane channel with an upper solid wall and a lower porous wall at Re_K = 5.91. The DNS results are in good agreement with available Particle Image Velocimetry (PIV) data for the same flow geometry. A linear stochastic estimation technique was used to capture the structure associated with the characteristic ejection event that contributes most to the Reynolds shear stress near the porous wall. This structure is similar to a horseshoe vortex. Contrary to the conventional hairpin vortex found near solid walls, this horseshoe vortex has a significantly higher inclination angle with the wall and its legs are much shorter. The latter is consistent with the observed absence of low and high-speed streaks near highly permeable walls. Next, the auto-generation mechanisms of the horseshoe vortex were studied in another DNS in which the horseshoe vortex was released in the Reynolds-averaged flow field obtained from the former DNS. Two distinct auto-generation mechanisms were observed: (1) the generation of new structures at the upstream end of the horseshoe vortex, which evolve rapidly into a turbulent spot with an arrowhead shape, and (2) the interaction of the horseshoe vortex with spanwise oriented Kelvin-Helmholtz vortex rollers originating from the inflexion point in the mean velocity profile near the porous wall
Scale interaction in a mixing layer: The role of the large-scale gradients
No full textThe interaction between scales is investigated in a turbulent mixing layer. The large-scale amplitude modulation of the small scales already observed in other works depends on the crosswise location. Large-scale positive fluctuations correlate with a stronger activity of the small scales on the low speed-side of the mixing layer, and a reduced activity on the high speed-side. However, from physical considerations we would expect the scales to interact in a qualitatively similar way within the flow and across different turbulent flows. Therefore, instead of the large-scale fluctuations, the large-scale gradients modulation of the small scales has been additionally investigated
Theory of spin and lattice wave dynamics excited by focused laser pulses
No full textWe develop a theory of spin wave dynamics excited by ultrafast focused laser pulses in a magnetic film. We take into account both the volume and surface spin wave modes in the presence of applied, dipolar and magnetic anisotropy fields and include the dependence on laser spot exposure size and magnetic damping. We show that the sound waves generated by local heating by an ultrafast focused laser pulse can excite a wide spectrum of spin waves (on top of a dominant magnon-phonon contribution). Good agreement with recent experiments supports the validity of the model.Accepted Author ManuscriptQN/Bauer Grou
Polonais d’origine juive volontaires de la guerre civile en Espagne (1936-1939)
No full textG. E. Sichon article is, first of all, an historical analysis, as the title suggests, of Polish Jews who participate in the International Brigades during the Spanish War. But this is also a major eye-witness account, since the author met most of the important protagonists. The article is illustrated with several of his own photographs, which he has generously given to the BDIC Collection.L’article de Gaby Ersler Sichon est d’abord une analyse historique sur les Polonais d’origine juive dans les Brigades internationales durant la guerre d’Espagne. Mais c’est aussi celle d’un témoin oculaire d’événements dont il a connu personnellement les protagonistes. L’article est illustré de photographies qu’il a prises, provenant d’un corpus généreusement déposé à la BDIC.Sichon G.e. Polonais d’origine juive volontaires de la guerre civile en Espagne (1936-1939). In: Matériaux pour l'histoire de notre temps, n°73, 2004. pp. 44-48
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