scispace - formally typeset
Search or ask a question
Institution

Vienna University of Technology

EducationVienna, Austria
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.


Papers
More filters
Journal ArticleDOI
TL;DR: In this article, the authors present the landmarks of the 30-odd-year evolution of ultrashort-pulse laser physics and technology culminating in the generation of intense few-cycle light pulses and discuss the impact of these pulses on high-field physics.
Abstract: The rise time of intense radiation determines the maximum field strength atoms can be exposed to before their polarizability dramatically drops due to the detachment of an outer electron. Recent progress in ultrafast optics has allowed the generation of ultraintense light pulses comprising merely a few field oscillation cycles. The arising intensity gradient allows electrons to survive in their bound atomic state up to external field strengths many times higher than the binding Coulomb field and gives rise to ionization rates comparable to the light frequency, resulting in a significant extension of the frontiers of nonlinear optics and (nonrelativistic) high-field physics. Implications include the generation of coherent harmonic radiation up to kiloelectronvolt photon energies and control of the atomic dipole moment on a subfemtosecond $(1{\mathrm{f}\mathrm{s}=10}^{\mathrm{\ensuremath{-}}15}\mathrm{}\mathrm{s})$ time scale. This review presents the landmarks of the 30-odd-year evolution of ultrashort-pulse laser physics and technology culminating in the generation of intense few-cycle light pulses and discusses the impact of these pulses on high-field physics. Particular emphasis is placed on high-order harmonic emission and single subfemtosecond extreme ultraviolet/x-ray pulse generation. These as well as other strong-field processes are governed directly by the electric-field evolution, and hence their full control requires access to the (absolute) phase of the light carrier. We shall discuss routes to its determination and control, which will, for the first time, allow access to the electromagnetic fields in light waves and control of high-field interactions with never-before-achieved precision.

2,547 citations

Journal ArticleDOI
TL;DR: The WIEN package as discussed by the authors uses LAPW's to calculate the LSDA total energy, spin densities, Kohn-Sham eigenvalues, and the electric field gradients at nuclear sites for a broad variety of space groups.

2,485 citations

Journal ArticleDOI
TL;DR: It is shown that the exact calculation of the electronic groundstate at each MD timestep is feasible using modern iterative matrix diagonalization algorithms and together with the use of ultrasoft pseudopotentials, ab initio MD simulations can be extended to open-shell transition metals with a high density of states at the Fermi-level.
Abstract: In recent years, ab initio molecular dynamics (MD) techniques have made a profound impact on the investigation of the structure of the electronic and dynamic properties of liquid and amorphous materials In this paper, recent developments in this field are reviewed and it is shown that the exact calculation of the electronic groundstate at each MD timestep is feasible using modern iterative matrix diagonalization algorithms Together with the use of ultrasoft pseudopotentials, ab initio MD simulations can be extended to open-shell transition metals with a high density of states at the Fermi-level The technique is applied to a number of interesting cases: (a) liquid simple metals (Li, Na, Al, Ge), (b) liquid transition metals (Cu, V), and (c) the transition from a liquid metal to an amorphous semiconductor by the rapid quenching of Ge

2,260 citations

Journal ArticleDOI
16 Feb 2017-PLOS ONE
TL;DR: Improvements in the relative accuracy considering the amount of variation explained, in comparison to the previous version of SoilGrids at 1 km spatial resolution, range from 60 to 230%.
Abstract: This paper describes the technical development and accuracy assessment of the most recent and improved version of the SoilGrids system at 250m resolution (June 2016 update). SoilGrids provides global predictions for standard numeric soil properties (organic carbon, bulk density, Cation Exchange Capacity (CEC), pH, soil texture fractions and coarse fragments) at seven standard depths (0, 5, 15, 30, 60, 100 and 200 cm), in addition to predictions of depth to bedrock and distribution of soil classes based on the World Reference Base (WRB) and USDA classification systems (ca. 280 raster layers in total). Predictions were based on ca. 150,000 soil profiles used for training and a stack of 158 remote sensing-based soil covariates (primarily derived from MODIS land products, SRTM DEM derivatives, climatic images and global landform and lithology maps), which were used to fit an ensemble of machine learning methods-random forest and gradient boosting and/or multinomial logistic regression-as implemented in the R packages ranger, xgboost, nnet and caret. The results of 10-fold cross-validation show that the ensemble models explain between 56% (coarse fragments) and 83% (pH) of variation with an overall average of 61%. Improvements in the relative accuracy considering the amount of variation explained, in comparison to the previous version of SoilGrids at 1 km spatial resolution, range from 60 to 230%. Improvements can be attributed to: (1) the use of machine learning instead of linear regression, (2) to considerable investments in preparing finer resolution covariate layers and (3) to insertion of additional soil profiles. Further development of SoilGrids could include refinement of methods to incorporate input uncertainties and derivation of posterior probability distributions (per pixel), and further automation of spatial modeling so that soil maps can be generated for potentially hundreds of soil variables. Another area of future research is the development of methods for multiscale merging of SoilGrids predictions with local and/or national gridded soil products (e.g. up to 50 m spatial resolution) so that increasingly more accurate, complete and consistent global soil information can be produced. SoilGrids are available under the Open Data Base License.

2,228 citations

Journal ArticleDOI
01 Jun 2007
TL;DR: Common architecture principles of context-aware systems are presented and a layered conceptual design framework is derived to explain the different elements common to mostcontext-aware architectures.
Abstract: Context-aware systems offer entirely new opportunities for application developers and for end users by gathering context data and adapting systems behaviour accordingly. Especially in combination with mobile devices, these mechanisms are of high value and are used to increase usability tremendously. In this paper, we present common architecture principles of context-aware systems and derive a layered conceptual design framework to explain the different elements common to most context-aware architectures. Based on these design principles, we introduce various existing context-aware systems focusing on context-aware middleware and frameworks, which ease the development of context-aware applications. We discuss various approaches and analyse important aspects in context-aware computing on the basis of the presented systems.

2,036 citations


Authors

Showing all 16934 results

NameH-indexPapersCitations
Krzysztof Matyjaszewski1691431128585
Wolfgang Wagner1562342123391
Marco Zanetti1451439104610
Sridhara Dasu1401675103185
Duncan Carlsmith1381660103642
Ulrich Heintz136168899829
Matthew Herndon133173297466
Frank Würthwein133158494613
Alain Hervé132127987763
Manfred Jeitler132127889645
David Taylor131246993220
Roberto Covarelli131151689981
Patricia McBride129123081787
David Smith1292184100917
Lindsey Gray129117081317
Network Information
Related Institutions (5)
École Polytechnique Fédérale de Lausanne
98.2K papers, 4.3M citations

94% related

Delft University of Technology
94.4K papers, 2.7M citations

94% related

ETH Zurich
122.4K papers, 5.1M citations

94% related

Georgia Institute of Technology
119K papers, 4.6M citations

93% related

RWTH Aachen University
96.2K papers, 2.5M citations

92% related

Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2023171
2022379
20212,527
20202,811
20192,846
20182,650