Institution
Jožef Stefan Institute
Facility•Ljubljana, Slovenia•
About: Jožef Stefan Institute is a facility organization based out in Ljubljana, Slovenia. It is known for research contribution in the topics: Liquid crystal & Dielectric. The organization has 3828 authors who have published 12614 publications receiving 291025 citations.
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TL;DR: In inverse treatment planning systems based on pencil beam algorithms alone should be upgraded either to superposition or Monte Carlo based dose calculations, because of the large systematic and convergence errors.
Abstract: The effect of dose calculation accuracy during inverse treatment planning for intensity modulated radiotherapy (IMRT) was studied in this work. Three dose calculation methods were compared: Monte Carlo, superposition and pencil beam. These algorithms were used to calculate beamlets. which were subsequently used by a simulated annealing algorithm to determine beamlet weights which comprised the optimal solution to the objective function. Three different cases (lung, prostate and head and neck) were investigated and several different objective functions were tested for their effect on inverse treatment planning. It is shown that the use of inaccurate dose calculation introduces two errors in a treatment plan, a systematic error and a convergence error. The systematic error is present because of the inaccuracy of the dose calculation algorithm. The convergence error appears because the optimal intensity distribution for inaccurate beamlets differs from the optimal solution for the accurate beamlets. While the systematic error for superposition was found to be approximately 1% of Dmax in the tumour and slightly larger outside, the error for the pencil beam method is typically approximately 5% of Dmax and is rather insensitive to the given objectives. On the other hand, the convergence error was found to be very sensitive to the objective function, is only slightly correlated to the systematic error and should be determined for each case individually. Our results suggest that because of the large systematic and convergence errors, inverse treatment planning systems based on pencil beam algorithms alone should be upgraded either to superposition or Monte Carlo based dose calculations.
119 citations
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TL;DR: In this paper, the results of the Direct Numerical Simulation (DNS) of the fully developed velocity and temperature fields in the two-dimensional turbulent channel flow coupled with the unsteady conduction in the heated walls was carried out.
Abstract: The Direct Numerical Simulation (DNS) of the fully developed velocity and temperature fields in the two-dimensional turbulent channel flow coupled with the unsteady conduction in the heated walls was carried out. Simulations were performed at constant friction Reynolds number 150 and Prandtl numbers between 0.71 and 7 considering the fluid temperature as a passive scalar. The obtained statistical quantities like root-mean-square temperature fluctuations and turbulent heat fluxes were verified with existing DNS studies obtained with ideal thermal boundary conditions. Results of the present study were compared to the findings of Polyakov (1974), who made a similar study with linearization of the fluid equations in the viscous sublayer that allowed analytical approach and results of Kasagi et al. (1989), who performed similar calculation with deterministic near-wall turbulence model and numerical approach. The present DNS results pointed to the main weakness of the previous studies, which underestimated the values of the wall temperature fluctuations for the limiting cases of the ideal-isoflux boundary conditions. With the results of the present DNS it can be decided, which behavior has to be expected in a real fluid-solid system and which one of the limiting boundary conditions is valid for calculation, or whether more expensive conjugate heat transfer calculation is required. @DOI: 10.1115/1.1389060#
119 citations
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TL;DR: In this article, aryl substituted ketones, cyclic ketones and 1,3-diketones were halogenated with N -halosuccinimides under solvent-free reaction conditions (SFRC) at various temperatures (20 −80 °C), whereas less enolized ketones required the presence of an acid catalyst.
119 citations
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TL;DR: In this article, solid-state synthesis of compositions from the Bi2O3-TeO2 system showed that, under an oxygen atmosphere, Te4+ oxidizes to Te6+ and yields four room-temperature stable compounds: Bi2Te2O8, BiTeO6, Bi6Te2 O15, and new compound with the nominal composition 7Bi2Te3·2TeOO2.
Abstract: Solid-state synthesis of compositions from the Bi2O3–TeO2 system show that, under an oxygen atmosphere, Te4+ oxidizes to Te6+ and yields four room-temperature stable compounds: Bi2Te2O8, Bi2TeO6, Bi6Te2O15, and new a compound with the nominal composition 7Bi2O3·2TeO2. Dense ceramics can be prepared from all these compounds by sintering between 650° and 800°C under an oxygen atmosphere. The permittivity of these compounds varies from ∼30 to ∼54, the Q×f value from 1.100 to 41.000 GHz (∼5 GHz), and the temperature coefficient of resonant frequency from −43 to −144 ppm/K. Bi6Te2O15 and 7Bi2O3·2TeO2 do not react with silver, and, therefore, they have the potential to be used for applications in low-temperature cofired ceramic (LTCC) technology.
119 citations
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TL;DR: Experiments that probe the self-assembly of micrometer-size colloids into one-particle-thick, robust, and self-healing membranes show that this generic aggregation scenario can be induced in any particles of large enough susceptibility.
Abstract: We report experiments that probe the self-assembly of micrometer-size colloids into one-particle-thick, robust, and self-healing membranes. In a magic-angle precessing magnetic field, superparamagnetic spheres experience isotropic pair attraction similar to the van der Waals force between atoms. But the many-body polarization interactions among them steer an ordered aggregation pathway consisting of growth of short chains, cross-linking and network formation, network coarsening, and consolidation of membrane patches. This generic aggregation scenario can be induced in any particles of large enough susceptibility.
119 citations
Authors
Showing all 3879 results
Name | H-index | Papers | Citations |
---|---|---|---|
Vladimir Cindro | 129 | 1157 | 82000 |
Igor Mandić | 128 | 1065 | 79498 |
Jure Leskovec | 127 | 473 | 89014 |
Matej Orešič | 82 | 352 | 26830 |
P. Križan | 78 | 749 | 26408 |
Jose Miguel Miranda | 76 | 336 | 18080 |
Vito Turk | 74 | 271 | 23205 |
Andrii Tykhonov | 73 | 270 | 24864 |
Masashi Yokoyama | 73 | 310 | 18817 |
Kostya Ostrikov | 72 | 763 | 21442 |
M. Starič | 71 | 530 | 19136 |
Boris Turk | 67 | 231 | 27006 |
Bostjan Kobe | 66 | 279 | 17592 |
Jure Zupan | 61 | 228 | 12054 |
Mario Sannino | 60 | 281 | 17144 |