63,162 research outputs found
I. Le qal futur en u des verbes à 2e radicale י
No full textLambert Mayer. I. Le qal futur en u des verbes à 2e radicale י. In: Revue des études juives, tome 83, n°166, avril-juin 1927. p. 207
Secular changes in anthropometric and physical characteristics of South African National U/20 rugby union players (1998-2010).
No full textIncludes abstract.Includes bibliographical references.The aim of this study was to compare changes in the physical and morphological characteristics of South Africa’s National U/20 rugby union players (Forwards and Backs) over a 12 year period from 1998 - 2010. This period spans an era starting just after the onset of professionalism of the game to the modern era where the influence of professionalism has filtered down to junior (U/20) levels. Any changes in morphology and physical ability of the players can be attributed to the changes in the demands of the game and reflect the characteristics that are required for a player to be successful at that level. Players who were U/20 at the time of representing the Junior South African National Team National over a period spanning from 1998 – 2010 were used for the study. A total of 453 players, split into two groups, Forwards (n = 256) and Backs (n = 197), underwent measurements of body mass, stature, body fat percentage, muscular endurance (pull ups), muscular strength (1RM bench press, sprint times (10m and 40m) and aerobic capacity (Multistage shuttle run test). All Tests were conducted once a year in either January or December of that year. Data are represented as means ± 95 % confidence intervals. A Levene’s test of homogeneity was used to determine whether the variance for each variable was equal. A two-way analysis of variance was used to determine whether there were significant differences for either main effect of ‘year’ or ‘position’ or for the interaction between ‘year x position’. If the main effect of ‘year’ or interaction (“year x position”) was significant, a Tukey post hoc test was used to identify specific differences. Statistical significance was accepted when p < 0.05
[Rezension zu:] Jens Balzer u. Lambert Wiesing: Outcault
No full textRezension zu Jens Balzer u. Lambert Wiesing: Outcault. Die Erfindung des Comic. Bochum, Essen (eh. A. Bachmann) 2010 (= yellow. schriften zur comicforschung, Bd. 3). 103 S.
In diesem 3. Band der Reihe 'yellow. schriften zur comicforschung' machen sich die Verfasser Jens Balzer und Lambert Wiesing auf die Suche nach der Urszene des Comics, nach jener "historischen Stätte, wo sich der (begrifflich noch zu bestimmende) Comic zum ersten Mal in aller wünschenswerten Klarheit zeigt." In vier Kapiteln, die auf Vorträge und Aufsätze zurückgehen und in der für das Buch überarbeiteten Fassung dennoch aufeinander aufbauen, entwickeln sie ihre These, dass der amerikanische Zeichner Richard Felton Outcault mit dem "Yellow Kid" eine neue Bildlichkeit entwickelte, die als Comic-Bild das Erzählen mit Bildern modernisierte und dem Medium bzw. der Gattung Comic ihre besondere Form gegeben hat
A Dynamic Subfilter-scale Stress Model for Large Eddy Simulations Based on Physical Flow Scales
No full textWe propose a new definition of the length scale in an eddy-viscosity model for large-eddy simulations (LES). This formulation extends and generalizes a previous proposal [Piomelli, Rouhi and Geurts, Proc. ETMM10, 2014], in which the LES length scale was expressed in terms of the integral length-scale of turbulence determined by the flow characteristics and explicitly decoupled from the simulation grid; this approach was named Integral Length-Scale Approximation (ILSA). As in the original ILSA, the model coefficient was determined by the user, and required to maintain a desired contribution of the unresolved, subfilter scales (SFS) to the global transport. We propose a local formulation (local ILSA) in which the model coefficient is local in space, allowing a precise control over SFS activity as a function of location. This new formulation preserves the properties of the global model; application to channel flow and backward-facing step verifies its features and accuracy
Large-eddy simulation of a separated flow with a sub-filter scale model based on the integral length-scale
No full textA new sub-filter scale model for large-eddy simulations, which uses a length-scale proportional to the integral scale of the turbulence instead of the grid resolution to parametrize the modelled stresses, will be assessed in the prediction of the flow of a boundary-layer over a rough surface, which includes separation and reattachment
Near Wall PIV-Measurements on the Windward Slope of a Hill
No full textThe turbulent flow over periodic hills was measured near to the wall, using planar Particle-Image-Velocimetry (PIV) at high spatial resolution. Our focus is on the near wall turbulence structure on the windward slope of the hill. For large-eddy simulation (LES) we suspect that, if this was not predicted accurately, it affects the prediction of the velocity profiles over the hill crest which in turn will affect the recirculation length downstream of the hill. Regarding the time averaged velocities, we were able to resolve the linear viscous region of the boundary layer. The velocity distribution and also the Reynolds stress does not comply with the law of the wall as it is valid for a turbulent boundary layer at equilibrium
Energy dissipation and flux laws for unsteady turbulence
No full textDirect Numerical Simulations of spatially periodic unsteady turbulence show that the high Reynolds number scalings of the instantaneous energy dissipation rate and interscale energy flux at intermediate wavenumbers are qualitatively different from the well-known cornerstone scalings of equilibrium turbulence where and are time-dependent rms velocity and integral length-scales. Instead, they both scale as where and are length and velocity scales characterizing initial/overall unsteady turbulence conditions
Direct numerical simulation of turbulent Couette-Poiseuille flow with zero skin friction
No full textThe near-wall scaling of mean velocity U(y) is addressed for the case of zero skin friction on one wall of a fully turbulent channel flow. The present DNS results can be added to the evidence in support of the conjecture that U is proportional to √yw in the region just above the wall at which the mean shear dU/dy = 0
Real-space Manifestations of Bottlenecks in Turbulence Spectra
No full textAn energy-spectrum bottleneck, a bump in the turbulence spectrum between the inertial and dissipation ranges, is shown to occur in the non-turbulent, one-dimensional, hyperviscous Burgers equation and found to be the Fourier-space signature of oscillations in the real-space velocity, which are explained by boundary-layer-expansion techniques. Pseudospectral simulations are used to show that such oscillations occur in velocity correlation functions in one- and three-dimensional hyperviscous hydrodynamical equations that display genuine turbulence
Braid Entropy of Faraday Waves driven 2D Turbulence
No full textWe report new experimental results that use tools from braid theory to characterize two-dimensional turbulent flows driven by Faraday waves. The average topological length of the material fluid lines is found to grow exponentially with time. It allows us to compute the braid’s topological entropy SBraid. We show that SBraid increases as the square root of the turbulence kinetic energy E ~ u^2, where u^2 is the horizontal velocity variance . At long times, the PDFs of Lbraid are positively skewed and present strong exponential tails
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