121,378 research outputs found
Inertial convection in rotating fluid spheres
No full textThe onset of convection in the form of inertial waves in a rotating fluid sphere is studied through a perturbation analysis in an extension of earlier work by Zhang (1994). Explicit expressions for the dependence of the Rayleigh number on the azimuthal wavenumber are derived and new results for the case of a nearly thermally insulating boundary are obtained
Ed. Claparède, Le mental et le physique d'après L. Busse
No full textBinet Alfred. Ed. Claparède, Le mental et le physique d'après L. Busse. In: L'année psychologique. 1903 vol. 10. p. 403
Ed. Claparède: Le mental et le physique d'après L. Busse. Revue analytique et critique. Arch. de psych. 3 (9), 81-100. 1903
No full textED. CLAPARÈDE: LE MENTAL ET LE PHYSIQUE D'APRÈS L. BUSSE. REVUE ANALYTIQUE ET CRITIQUE. ARCH. DE PSYCH. 3 (9), 81-100. 1903
Zeitschrift für Psychologie und Physiologie der Sinnesorgane (-)
Zeitschrift für Psychologie und Physiologie der Sinnesorgane (38) (a0001)
Ed. Claparède: Le mental et le physique d'après L. Busse. Revue analytique et critique. Arch. de psych. 3 (9), 81-100. 1903 (38) (p0200
Parametric forcing approach to rough-wall turbulent channel flow
No full textThe effects of rough surfaces on turbulent channel flow are modelled by an extra force term in the Navier–Stokes equations. This force term contains two parameters, related to the density and the height of the roughness elements, and a shape function, which regulates the influence of the force term with respect to the distance from the channel wall. This permits a more flexible specification of a rough surface than a single parameter such as the equivalent sand grain roughness. The effects of the roughness force term on turbulent channel flow have been investigated for a large number of parameter combinations and several shape functions by direct numerical simulations. It is possible to cover the full spectrum of rough flows ranging from hydraulically smooth through transitionally rough to fully rough cases. By using different parameter combinations and shape functions, it is possible to match the effects of different types of rough surfaces. Mean flow and standard turbulence statistics have been used to compare the results to recent experimental and numerical studies and a good qualitative agreement has been found. Outer scaling is preserved for the streamwise velocity for both the mean profile as well as its mean square fluctuations in all but extremely rough cases. The structure of the turbulent flow shows a trend towards more isotropic turbulent states within the roughness layer. In extremely rough cases, spanwise structures emerge near the wall and the turbulent state resembles a mixing layer. A direct comparison with the study of Ashrafian, Andersson & Manhart (Intl J. Heat Fluid Flow, vol. 25, 2004, pp. 373–383) shows a good quantitative agreement of the mean flow and Reynolds stresses everywhere except in the immediate vicinity of the rough wall. The proposed roughness force term may be of benefit as a wall model for direct and large-eddy numerical simulations in cases where the exact details of the flow over a rough wall can be neglecte
Ulrich Busse, Die Wunder des Propheten Jesus. Die Rezeption, Komposition und Interpretation der Wundertradition im Evangelium des Lukas. 1977
No full textDescamps A.-L. Ulrich Busse, Die Wunder des Propheten Jesus. Die Rezeption, Komposition und Interpretation der Wundertradition im Evangelium des Lukas. 1977. In: Revue théologique de Louvain, 10ᵉ année, fasc. 2, 1979. pp. 229-232
Numerical simulations of rotating axisymmetric sunspots
No full textA numerical model of axisymmetric convection in the presence of a vertical magnetic flux bundle and rotation about the axis is presented. The model contains a compressible plasma described by the non-linear MHD equations, with density and temperature gradients simulating the upper layer of the Sun's convection zone. The solutions exhibit a central magnetic flux tube in a cylindrical numerical domain, with convection cells forming collar flows around the tube. When the numerical domain is rotated with a constant angular velocity, the plasma forms a Rankine vortex, with the plasma rotating as a rigid body where the magnetic field is strong, as in the flux tube, while experiencing sheared azimuthal flow in the surrounding convection cells, forming a free vortex. As a result, the azimuthal velocity component has its maximum value close to the outer edge of the flux tube. The azimuthal flow inside the magnetic flux tube and the vortex flow is prograde relative to the rotating cylindrical reference frame. A retrograde flow appears at the outer wall. The most significant convection cell outside the flux tube is the location for the maximum value of the azimuthal magnetic field component. The azimuthal flow and magnetic structure are not generated spontaneously, but decay exponentially in the absence of any imposed rotation of the cylindrical domain
Improving behavioral performance under full attention by adjusting response criteria to changes in stimulus predictability
No full textOne of the key features of active perception is the ability to predict critical sensory events. Humans and animals can implicitly learn statistical regularities in the timing of events and use them to improve behavioral performance. Here, we used a signal detection approach to investigate whether such improvements in performance result from changes of perceptual sensitivity or rather from adjustments of a response criterion. In a regular sequence of briefly presented stimuli, human observers performed a noise-limited motion detection task by monitoring the stimulus stream for the appearance of a designated target direction. We manipulated target predictability through the hazard rate, which specifies the likelihood that a target is about to occur, given it has not occurred so far. Analyses of response accuracy revealed that improvements in performance could be accounted for by adjustments of the response criterion; a growing hazard rate was paralleled by an increasing tendency to report the presence of a target. In contrast, the hazard rate did not affect perceptual sensitivity. Consistent with previous research, we also found that reaction time decreases as the hazard rate grows. A simple rise-to-threshold model could well describe this decrease and attribute predictability effects to threshold adjustments rather than changes in information supply. We conclude that, even under conditions of full attention and constant perceptual sensitivity, behavioral performance can be optimized by dynamically adjusting the response criterion to meet ongoing changes in the likelihood of a target
- …
