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13. Strong events in the sand-pile modelAlexander Shapoval, M. Shnirman, 2004, izvirni znanstveni članek Opis: Here is a sand-pile introduced by Bak et al. The system accumulates particles one by one. From time to time it topples. Every toppling initiates an event. The distribution of the events' size follows a power law for all the events except the strongest ones. The fraction of the strongest events does not depend on the system length. The number of particles and their clustering increase before the strongest events.
Ključne besede: sandpile, prediction, power-law
Objavljeno v RUNG: 19.04.2021; Ogledov: 2803; Prenosov: 0
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15. Ki(n) : accompanying the self towards a Lived Ethics of planetary kinship and care2020, radijska ali televizijska oddaja, podkast, intervju, novinarska konferenca Ključne besede: interspecies reciprocity, language of kinship, 1-2-1 performance, power relations, the gaze, feedback loop, lived experience
Objavljeno v RUNG: 23.02.2021; Ogledov: 3418; Prenosov: 12
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17. A pyrrolopyridazinedione-based copolymer for fullerene-free organic solar cellsAstrid-Caroline Knall, Samuel Rabensteiner, Sebastian F. Hoefler, Matiss Reinfelds, Mathias Hobisch, Heike M. A. Ehmann, Nadiia Pastukhova, Egon Pavlica, Gvido Bratina, Illie Hanzu, Shuguang Wen, Renqiang Yang, Gregor Trimmel, Thomas Rath, 2021, izvirni znanstveni članek Opis: The recent success of non-fullerene acceptors in organic photovoltaics also entails a change in the requirements to the polymer donor in terms of optical and morphological properties leading to a demand for novel conjugated polymers. Herein, we report on the synthesis of a 1,4-bis-(thiophene-2-yl)-pyrrolopyridazinedione based copolymer with 2-ethylhexyl substituents on the pyrrolopyridazinedione moiety. A 2D conjugated benzodithiophene (BDT) was chosen as comonomer. The resulting copolymer T-EHPPD-T-EHBDT showed a molecular weight of 10.2 kDa, an optical band gap of 1.79 eV, a hole mobility of 1.8 × 10−4 cm2 V−1 s−1 and a preferred face-on orientation with regard to the substrate. The comparably wide band gap as well as the determined energy levels (HOMO: −5.47 eV, LUMO: −3.68 eV) match well with the narrow band gap non-fullerene acceptor ITIC-F, which was used as the acceptor phase in the bulk heterojunction absorber layers in the investigated solar cells. The solar cells, prepared in inverted architecture, revealed power conversion efficiencies up to 7.4% using a donor:acceptor ratio of 1 : 1 in the absorber layer.
Ključne besede: non-fullerene solar cells, charge transport, charge mobility, power conversion efficiency
Objavljeno v RUNG: 27.01.2021; Ogledov: 3952; Prenosov: 0
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19. Near-Ground Profile of Bora Wind Speed at Razdrto, SloveniaMarija Bervida, Samo Stanič, Klemen Bergant, Benedikt Strajnar, 2019, izvirni znanstveni članek Opis: Southwest Slovenia is a region well-known for frequent episodes of strong and gusty Bora wind, which may damage structures, affect traffic, and poses threats to human safety in general. With the increased availability of computational power, the interest in high resolution modeling of Bora on local scales is growing. To model it adequately, the flow characteristics of Bora should be experimentally investigated and parameterized. This study presents the analysis of wind speed vertical profiles at Razdrto, Slovenia, a location strongly exposed to Bora during six Bora episodes of different duration, appearing between April 2010 and May 2011. The empirical power law and the logarithmic law for Bora wind, commonly used for the description of neutrally stratified atmosphere, were evaluated for 10-min averaged wind speed data measured at four different heights. Power law and logarithmic law wind speed profiles, which are commonly used in high resolution computational models, were found to approximate well the measured data. The obtained power law coefficient and logarithmic law parameters, which are for modeling purposes commonly taken to be constant for a specific site, were found to vary significantly between different Bora episodes, most notably due to different wind direction over complex terrain. To increase modeling precision, the effects of local topography on wind profile parameters needs to be experimentally assessed and implemented.
Ključne besede: Bora wind, logarithmic law, power law, roughness length, wind profile
Objavljeno v RUNG: 04.10.2019; Ogledov: 4864; Prenosov: 114
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20. Bora wind, Wind speed vertical profile, Logarithmic law, Power lawMarija Bervida, Samo Stanič, Klemen Bergant, 2018, objavljeni znanstveni prispevek na konferenci Opis: Bora is cold and gusty downslope wind with variable gust frequency and duration, appearing on the lee side of Dinaric Alps. Its flow characteristics are unique and theoretically still not fully described, especially for modeling purposes. We present an analysis of the wind speed vertical profiles at Razdrto, which lies in a gap between the Nanos and Javorniki plateau in southwest Slovenia and is strongly exposed to Bora. An analysis of the vertical wind speed profiles during Bora episodes is based on experimental wind data, provided by Helikopter energija, for six Bora events of different duration, appearing between April 2010 and May 2011. Average wind speed in 10-minute intervals was collected at four different heights (20, 31, 40 and 41.7 m above the ground)at the wind turbine site in Razdrto using cup anemometers. Wind direction data with same temporal resolution was obtained from a single wind vane placed at 40.9 m above the ground. Based on the collected data, the applicability of the empirical power-law and the logarithmic law profiles, commonly used for the description of neutrally stratified atmosphere, was investigated for the case of Bora. The parameters for the power-law and logarithmic law were obtained by fitting the wind speed data using linear regression method and are compared to standard values for that particular type of terrain. The quality of fits was very good with r2 above 0.9, indicating that both power-law and logarithmic law adequately describe mean horizontal Bora wind. The median value of the power-law coefficient was found to be 0.16±0.03, which is consistent with standard value for neutral atmosphere (0.143). The aerodynamic roughness varied from 0.003 m to 0.22 m with the median value of 0.09±0.07, which describes open level country terrain with some trees. The event in November 2010 with large roughness is expected to be due to specific wind direction and surface conditions.
Ključne besede: Bora wind, Wind speed vertical profile, Logarithmic law, Power law
Objavljeno v RUNG: 07.02.2019; Ogledov: 5480; Prenosov: 29
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