Franz Schubert, Büste

Signatur des Originals: S 36/F09829

Geburtshaus von Franz Schubert in Wien

Signatur des Originals: S 36/F09830

Franz Schubert's Grabmal auf dem Währinger Friedhof bei Wien

Signatur des Originals: S 36/F09831

Franz Schubert, Denkmal, Wien

Signatur des Originals: S 36/F09832

Franz Schubert, Totenschädel, Exhumation took place Oct. 13. 1863

Signatur des Originals: S 36/F11121

Inez Fabbri-Mulder als Ludmilla, Rollenbild, in: Franz Schubert: Der häusliche Krieg

Signatur des Originals: S 36/F11517

Franz Schubert, Brustbild

Signatur des Originals: S 36/F12155

Franz Schubert, Brustbild - Liedanfang: Franz Schubert: Müllerlieder

Signatur des Originals: S 36/F12356

Franz Schubert, Brustbild

Signatur des Originals: S 36/G02203

Franz Schubert, Brustbild

Signatur des Originals: S 36/G02204

Georgine Schubert, Kniestück, Profil

Signatur des Originals: S 36/G02205

Franz Schubert, Brustbild

Signatur des Originals: S 36/G04379

Franz Schubert, Brustbild

Signatur des Originals: S 36/G04604

Use of calculus of variations to determine the shape of hovering rotors of minimum power and its application to micro air vehicles

In this paper, calculus of variations and combined blade element and momentum theory (BEMT) are used to demonstrate that, in hover, when neither root nor tip losses are considered; the rotor, which minimizes the total power (MPR), generates an induced velocity that varies linearly along the blade span. The angle of attack of every blade element is constant and equal to its optimum value. The traditional ideal twist (ITR) and optimum (OR) rotors are revisited in the context of this variational framework. Two more optimum rotors are obtained considering root and tip losses, the ORL, and the MPRL. A comparison between these five rotors is presented and discussed. The MPR and MPRL present a remarkable saving of power for low values of both thrust coefficient and maximum aerodynamic efficiency. The result obtained can be exploited to improve the aerodynamic behaviour of rotary wing micro air vehicles (MAV). A comparison with experimental results obtained from the literature is presented.

Calculus of the uncertainty in acoustic field measurements: comparative study between the uncertainty propagation method and the distribution propagation method

The new Spanish Regulation in Building Acoustic establishes values and limits for the different acoustic magnitudes whose fulfillment can be verify by means field measurements. In this sense, an essential aspect of a field measurement is to give the measured magnitude and the uncertainty associated to such a magnitude. In the calculus of the uncertainty it is very usual to follow the uncertainty propagation method as described in the Guide to the expression of Uncertainty in Measurements (GUM). Other option is the numerical calculus based on the distribution propagation method by means of Monte Carlo simulation. In fact, at this stage, it is possible to find several publications developing this last method by using different software programs. In the present work, we used Excel for the Monte Carlo simulation for the calculus of the uncertainty associated to the different magnitudes derived from the field measurements following ISO 140-4, 140-5 and 140-7. We compare the results with the ones obtained by the uncertainty propagation method. Although both methods give similar values, some small differences have been observed. Some arguments to explain such differences are the asymmetry of the probability distributions associated to the entry magnitudes,the overestimation of the uncertainty following the GUM