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Institution

Johannes Kepler University of Linz

EducationLinz, Oberösterreich, Austria
About: Johannes Kepler University of Linz is a education organization based out in Linz, Oberösterreich, Austria. It is known for research contribution in the topics: Thin film & Quantum dot. The organization has 6605 authors who have published 19243 publications receiving 385667 citations.


Papers
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Journal ArticleDOI
TL;DR: This paper describes a language interface for an extended NF2 model, i.e. a model which covers a much broader range of data structures than the original [17] NF’ model, and does not appropriately match further vital needs of new database applications.

90 citations

Journal ArticleDOI
04 Feb 2020-Sensors
TL;DR: The theoretical capabilities of a number of prominent SHM methods are demonstrated by comparing their fundamental physical models to the actual effects of damage on metal and composite structures.
Abstract: Structural health monitoring (SHM) is the continuous on-board monitoring of a structure's condition during operation by integrated systems of sensors. SHM is believed to have the potential to increase the safety of the structure while reducing its deadweight and downtime. Numerous SHM methods exist that allow the observation and assessment of different damages of different kinds of structures. Recently data fusion on different levels has been getting attention for joint damage evaluation by different SHM methods to achieve increased assessment accuracy and reliability. However, little attention is given to the question of which SHM methods are promising to combine. The current article addresses this issue by demonstrating the theoretical capabilities of a number of prominent SHM methods by comparing their fundamental physical models to the actual effects of damage on metal and composite structures. Furthermore, an overview of the state-of-the-art damage assessment concepts for different levels of SHM is given. As a result, dynamic SHM methods using ultrasonic waves and vibrations appear to be very powerful but suffer from their sensitivity to environmental influences. Combining such dynamic methods with static strain-based or conductivity-based methods and with additional sensors for environmental entities might yield a robust multi-sensor SHM approach. For demonstration, a potent system of sensors is defined and a possible joint data evaluation scheme for a multi-sensor SHM approach is presented.

90 citations

Journal ArticleDOI
TL;DR: The method is evaluated, which is based on high-dimensional data from industrial processes and based on benchmark datasets from the Internet and compared with well-known batch-training methods, in terms of accuracy and complexity of the fuzzy systems.
Abstract: In this paper, we deal with a novel data-driven learning method [sparse fuzzy inference systems (SparseFIS)] for Takagi-Sugeno (T-S) fuzzy systems, extended by including rule weights. Our learning method consists of three phases: The first phase conducts a clustering process in the input/output feature space with iterative vector quantization and projects the obtained clusters onto 1-D axes to form the fuzzy sets (centers and widths) in the antecedent parts of the rules. Hereby, the number of clusters = rules is predefined and denotes a kind of upper bound on a reasonable granularity. The second phase optimizes the rule weights in the fuzzy systems with respect to least-squares error measure by applying a sparsity-constrained steepest descent-optimization procedure. Depending on the sparsity threshold, weights of many or a few rules can be forced toward 0, thereby, switching off (eliminating) some rules (rule selection). The third phase estimates the linear consequent parameters by a regularized sparsity-constrained-optimization procedure for each rule separately (local learning approach). Sparsity constraints are applied in order to force linear parameters to be 0, triggering a feature-selection mechanism per rule. Global feature selection is achieved whenever the linear parameters of some features in each rule are (near) 0. The method is evaluated, which is based on high-dimensional data from industrial processes and based on benchmark datasets from the Internet and compared with well-known batch-training methods, in terms of accuracy and complexity of the fuzzy systems.

90 citations

Journal ArticleDOI
TL;DR: It is demonstrated that epitaxially grown Ge quantum dots (QDs) in a defect-free Si matrix show extraordinary optical properties if partially amorphized by Ge-ion bombardment (GIB), in contrast to conventional SiGe nanostructures.
Abstract: Semiconductor light-emitters compatible with standard Si integration technology (SIT) are of particular interest for overcoming limitations in the operating speed of microelectronic devices. Light sources based on group IV elements would be SIT-compatible, but suffer from the poor optoelectronic properties of bulk Si and Ge. Here we demonstrate that epitaxially grown Ge quantum dots (QDs) in a defect-free Si matrix show extraordinary optical properties if partially amorphized by Ge-ion bombardment (GIB). In contrast to conventional SiGe nanostructures, these QDs exhibit dramatically shortened carrier lifetimes and negligible thermal quenching of the photoluminescence (PL) up to room temperature. Microdisk resonators with embedded GIB-QDs exhibit threshold behavior as well as a superlinear increase of the integrated PL intensity with concomitant line width narrowing as the pump power increases. These findings demonstrate light amplification by stimulated emission in a fully SIT-compatible group IV nanosystem.

90 citations

Journal ArticleDOI
TL;DR: In this article, the use of 2-aminopyridine as derivatizing agent allows sensitive direct UV detection of saccharides in the fmol range, including disaccharides and aldonic acids, without the need for derivatization.
Abstract: The analysis of carbohydrates has been always hampered by their lack of UV absorbance above 200 nm, which is an especially challenging problem in capillary electrophoresis due to the very small (nl) sample volumes injected. The introduction of 2-aminopyridine as derivatizing agent allows sensitive direct UV detection of saccharides in the fmol range. However, due to the requirement of the presence of a free aldehyde group only aldoses and uronic acids can be determined. This limitation was recently overcome by means of precolumn derivatization withp-aminobenzoic acid or ethylp-aminobenzoate, which permits the analysis of fructose with a lower mass detection limit of 0.3 and 0.14 pmol, respectively. The detection limits for aldoses were even as low as 15 and 7 fmol. A more universal approach is the use of indirect UV detection, which permits the analysis of carbohydrates, including (1–2)-linked disaccharides and aldonic acids, at the lower pmol level without the need for derivatization.

90 citations


Authors

Showing all 6718 results

NameH-indexPapersCitations
Wolfgang Wagner1562342123391
A. Paul Alivisatos146470101741
Klaus-Robert Müller12976479391
Christoph J. Brabec12089668188
Andreas Heinz108107845002
Niyazi Serdar Sariciftci9959154055
Lars Samuelson9685036931
Peter J. Oefner9034830729
Dmitri V. Talapin9030339572
Tomás Torres8862528223
Ramesh Raskar8667030675
Siegfried Bauer8442226759
Alexander Eychmüller8244423688
Friedrich Schneider8255427383
Maksym V. Kovalenko8136034805
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20242
202354
2022187
20211,404
20201,412
20191,365