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Helsinki University of Technology

About: Helsinki University of Technology is a based out in . It is known for research contribution in the topics: Thin film & Vortex. The organization has 8962 authors who have published 20136 publications receiving 723787 citations. The organization is also known as: TKK & Teknillinen korkeakoulu.


Papers
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Journal ArticleDOI
TL;DR: In this paper, the electronic and atomic structures of monovacancies and antisite defects in 4H-SiC in all possible charge states were analyzed using a plane-wave pseudopotential method based on density-functional theory and local spin-density approximation.
Abstract: We present results of ab initio calculations for the electronic and atomic structures of monovacancies and antisite defects in 4H-SiC in all possible charge states. The calculations make use of a plane-wave pseudopotential method based on density-functional theory and the local spin-density approximation. Formation energies, ionization levels, and local geometries of the relaxed structures are reported for defects at all possible cubic and hexagonal lattice sites. To correct for the electrostatic interaction between charged supercells, we use a Madelung-type correction for the formation energies, leading to good agreement with experimentally observed ionization levels. Our calculations indicate no negative-U behaviour for carbon vacancies. Hence, the singly positive charge state of the carbon vacancy VC+ is stable, as recently found in experiments. The silicon antisite SiC+ is found to be stable at low values of electron chemical potential—again in agreement with experiment.

152 citations

Journal ArticleDOI
TL;DR: In this paper, the authors considered estimating non-discrete physical quantities from indirect linear measurements and showed that the discretization of the unknown quantity can be arbitrarily fine regardless of the number of measurements.
Abstract: Estimation of non-discrete physical quantities from indirect linear measurements is considered. Bayesian solution of such an inverse problem involves discretizing the problem and expressing available a priori information in the form of a prior distribution in a finite-dimensional space. Since a priori information is independent of the measurement, the discretization of the unknown quantity can be arbitrarily fine regardless of the number of measurements. The main result is that Bayesian conditional mean estimates for total variation prior distribution are not edge-preserving with very fine discretizations of the model space. Theoretical findings are illustrated by a numerical example with computer simulated data.

152 citations

Journal ArticleDOI
TL;DR: In this paper, the particle swarm was used to find solutions to a specific dual-beam array problem in two ways: first, the PSO optimized the Woodward-Lawson coefficients, and second, the element excitation amplitudes and phases directly.
Abstract: ing. The particle swarm was used to find solutions to a specific dual-beam array problem in two ways. First, the PSO optimized the Woodward–Lawson coefficients. Second, the PSO optimized the element excitation amplitudes and phases directly. Both methods provided acceptable solutions to the problem, but the second method was found to be more straightforward both conceptually and in practice. In real-life applications, errors in power dividing networks and sampling error associated with binary phase shifters are inevitable, and practical arrays must be able to maintain acceptable performance in spite of these imperfections. The particle swarm-optimized reconfigurable array designs were found to be resistant to simulated variations in the excitation coefficients. Future work with the particle swarm might extend to many different areas of antenna design and analysis. The PSO program developed at UCLA has the ability to be linked to nearly any numerical simulation program available, and is therefore capable of optimizing any structure that can be numerically simulated. In particular, multiple-beam array problems could be approached using more degrees of freedom than are utilized in the present work. For example, the element position and geometry could be optimized in addition to the array excitation to achieve even more complex multiple-beam patterns.

152 citations

Journal ArticleDOI
TL;DR: Tissue and subcellular localization data indicate that RCD1 and SRO1 have partially overlapping functions in plant development, and full genome array analysis indicated that in many cases targets of these transcription factors have altered expression in the rcd1 but not the sro1 mutant.
Abstract: RADICAL-INDUCED CELL DEATH1 (RCD1) is an important regulator of stress and hormonal and developmental responses in Arabidopsis thaliana. Together with its closest homolog, SIMILAR TO RCD-ONE1 (SRO1), it is the only Arabidopsis protein containing the WWE domain, which is known to mediate protein-protein interactions in other organisms. Additionally, these two proteins contain the core catalytic region of poly-ADP-ribose transferases and a conserved C-terminal domain. Tissue and subcellular localization data indicate that RCD1 and SRO1 have partially overlapping functions in plant development. In contrast mutant data indicate that rcd1 has defects in plant development, whereas sro1 displays normal development. However, the rcd1 sro1 double mutant has severe growth defects, indicating that RCD1 and SRO1 exemplify an important genetic principle - unequal genetic redundancy. A large pair-wise interaction test against the REGIA transcription factor collection revealed that RCD1 interacts with a large number of transcription factors belonging to several protein families, such as AP2/ERF, NAC and basic helix-loop-helix (bHLH), and that SRO1 interacts with a smaller subset of these. Full genome array analysis indicated that in many cases targets of these transcription factors have altered expression in the rcd1 but not the sro1 mutant. Taken together RCD1 and SRO1 are required for proper plant development.

151 citations

Journal ArticleDOI
TL;DR: In this article, the authors review the recent developments in the functional chain from climate models to climate scenarios, through hydrology all the way to water resources management, design and policy making.
Abstract: This article reviews the recent developments in the functional chain from climate models to climate scenarios, through hydrology all the way to water resources management, design and policy making. Although climate models, such as Global Circulation Models (GCMs) continue to evolve, their outputs remain crude and often even inappropriate to watershed-scale hydrological analyses. The bridging techniques are evolving, though. Many families of regionalization technologies are under progress in parallel. Perhaps the most important advances are in the field of regional weather patterns, such as ENSO (El Nino-Southern Oscillation), NAO (North Atlantic Oscillation) and many more. The gap from hydrology to water resources development is by far not that wide. The traditional and contemporary practices are well in place. In climate change studies, the bottleneck is not in this link itself but in the climatic input. The tendency seems to be towards integrated water resources assessments, where climate is only one among many changes that are expected to occur, such as demography, land cover and land use, economy, technologies, and so forth. In such a pragmatic setting a risk–analytic interpretation of those scenarios is often called for. The above-outlined continuum from climate to water is a topic where the physically based modelers, the empiricists and the pragmatists should not get restricted to their own way of thinking. The issues should develop hand in hand. Perhaps the greatest challenge is to incorporate and respect the pragmatic policy-related component to the two other branches. For this purpose, it is helpful to reverse the direction of thinking from time to time to start—instead of climate models—from practical needs and think how the climate scenarios and models help really in the difficult task of designing better water structures, outline better policies and formulate better operational rules in the water field.

151 citations


Authors

Showing all 8962 results

NameH-indexPapersCitations
Ashok Kumar1515654164086
Hannu Kurki-Suonio13843399607
Nicolas Gisin12582764298
Anne Lähteenmäki11648581977
Riitta Hari11149143873
Andreas Richter11076948262
Mika Sillanpää96101944260
Markku Leskelä9487636881
Ullrich Scherf9273536972
Mikko Ritala9158429934
Axel H. E. Müller8956430283
Karl Henrik Johansson88108933751
T. Poutanen8612033158
Elina Lindfors8642023846
Günter Breithardt8555433165
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
2021154
2020153
2019155
201851
201714
201630