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2. Nanoscopic roughness characterization of chitosan with buried graphene oxide for fuel cell applicationAhmed Kreta, Egon Pavlica, Mojca Božič, Gvido Bratina, 2023, published scientific conference contribution Keywords: AFM, chitosan, graphene oxide, fuel cells, membrane, roughness
Published in RUNG: 01.03.2023; Views: 1323; Downloads: 3
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4. Fractal and inertia moment analyses for thin film quality monitoringMohanachandran Nair Sindhu Swapna, 2022, original scientific article Abstract: The widespread applications of thin films in optronics demand innovative techniques for its characterizations. The work reported here proposes electronic speckle pattern interferometry and fractal-based methods for assessing the quality of thin films taking the industrially relevant molybdenum oxide (MoO3) incorporated niobium oxide (Nb2O5) films. The films with different levels of MoO3 incorporation (1, 2, 3, 5, and 10 wt. %) are prepared by radio frequency sputtering. The study reveals the structure modifications of Nb2O5 from the orthorhombic to monoclinic phases with an associated morphological variation revealed through atomic force microscopy and field-emission scanning electron microscopy analyses. The films’ specklegrams are recorded under thermal stress; the inertia moment (IM) and fractal analyses are computed and compared with the root-mean-square surface roughness of the films. The lacunarity analysis of the AFM films agrees well with the specklegrams. Thus, the lower IM and lacunarity values of the specklegrams can be regarded as indicators of the good quality of thin films.
Keywords: cross-correlation, fractal dimension, inertia moment, lacunarity, speckle, surface roughness.
Published in RUNG: 30.06.2022; Views: 1195; Downloads: 0
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5. Near-Ground Profile of Bora Wind Speed at Razdrto, SloveniaMarija Bervida, Samo Stanič, Klemen Bergant, Benedikt Strajnar, 2019, original scientific article Abstract: 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.
Keywords: Bora wind, logarithmic law, power law, roughness length, wind profile
Published in RUNG: 04.10.2019; Views: 3481; Downloads: 109
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