Vienna University of Technology

About: Vienna University of Technology is a education organization based out in Vienna, Austria. It is known for research contribution in the topics: Laser & Cloud computing. The organization has 16723 authors who have published 49341 publications receiving 1302168 citations.

An evaluation of open source e-learning platforms stressing adaptation issues

Abstract: This paper presents an evaluation of open source e-learning platforms. The main focus is on adaptation issues. The result of the evaluation shows that the platform Moodle outperforms all other platforms and also obtained the best rating in the adaptation category.

A possible solution for the problem of estimating the error structure of global soil moisture data sets

Abstract: [1] In the last few years, research made significant progress towards operational soil moisture remote sensing which lead to the availability of several global data sets. For an optimal use of these data, an accurate estimation of the error structure is an important condition. To solve for the validation problem we introduce the triple collocation error estimation technique. The triple collocation technique is a powerful tool to estimate the root mean square error while simultaneously solving for systematic differences in the climatologies of a set of three independent data sources. We evaluate the method by applying it to a passive microwave (TRMM radiometer) derived, an active microwave (ERS-2 scatterometer) derived and a modeled (ERA-Interim reanalysis) soil moisture data sets. The results suggest that the method provides realistic error estimates. Citation: Scipal, K., T. Holmes, R. de Jeu, V. Naeimi, and W. Wagner (2008), A possible solution for the problem of estimating the error structure of global soil moisture data sets, Geophys. Res. Lett., 35, L24403, doi:10.1029/2008GL035599.

First-principles calculations of the radial breathing mode of single-wall carbon nanotubes

Abstract: The radial breathing mode is a promising candidate for the analysis of conformational and electronic properties of carbon nanotubes. The paper presents calculations based on the local density approximation to determine the radial breathing mode (RBM) frequency of various zigzag and armchair tubes with radii between 3.5 and 8.1 \AA{}. The frequencies are derived from both frozen phonon calculations for nanotubes and from the elastic constants of the flat graphene sheet. The RBM frequency of the (10,10) armchair tube is found to be $175{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ and $174{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}$ for the two techniques, respectively. These values are in very good agreement with one of the strongest components in the structured Raman band of the radial breathing modes observed at $177{\mathrm{cm}}^{\mathrm{\ensuremath{-}}1}.$ Since the RBM frequency turns out to scale with $1/R$ the calculations also allow one to evaluate the frequency of this mode for tubes with arbitrary chirality.

Sustainable Synthesis of Quinolines and Pyrimidines Catalyzed by Manganese PNP Pincer Complexes.

Abstract: This study represents the first example an environmentally benign, sustainable, and practical synthesis of substituted quinolines and pyrimidines using combinations of 2-aminobenzyl alcohols and alcohols as well as benzamidine and two different alcohols, respectively. These reactions proceed with high atom efficiency via a sequence of dehydrogenation and condensation steps that give rise to selective C–C and C–N bond formations, thereby releasing 2 equiv of hydrogen and water. A hydride Mn(I) PNP pincer complex recently developed in our laboratory catalyzes this process in a very efficient way. A total of 15 different quinolines and 14 different pyrimidines were synthesized in isolated yields of up to 91 and 90%, respectively.