1. Experimental study of the burning behavior and key parameters of gasoline pool fires with different ullage heightsJinlong Zhao, Xinjiang Li, Zhenqi Hu, Rongxue Kang, Grunde Jomaas, 2023, izvirni znanstveni članek Povzetek: Pool fires with different ullage heights are a common type of fire accident. A series of gasoline pool fire ex- periments with two sizes (D = 40 cm, 60 cm) and six ullage heights (h = 0, 0.2D, 0.4D, 0.6D, 0.8D, 1.0D) are conducted. The burning process, axial temperature profile, radiative heat feedback, and burning rate are measured and analyzed. The result shows that the fuel vapor layer and the down-reaching flame layer are distinguished based on the axial temperature profile for the steady burning stage. Meanwhile, the down-reaching flame length (Ldown) increases more profoundly for large tank diameters under the same ullage height. Subse- quently, the dimensionless down-reaching flame length (Ldown* = Ldown/D) increases exponentially with the dimensionless ullage heights (h* = h/D). Finally, based on the classical burning rate model for the low ullage height and the heat transfer process from the flame to the fuel surface, a correlation with different ullage heights is established to calculate the burning rate, which is then validated against the experimental data in the paper and literature values. The results are of importance to understand the burning rate and the radiative heat feedback to the fuel surface for pool fires with different ullage heights.
Ključne besede: pool fires, ullage height, down-reaching flame, flame radiative heat feedback, burning rate correlation
Objavljeno v DiRROS: 08.01.2024; Ogledov: 175; Prenosov: 38
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2. Photo, thermal and photothermal activity of ▫$TiO_2$▫ supported Pt catalysts for plasmon-driven environmental applicationsGregor Žerjav, Zafer Say, Janez Zavašnik, Matjaž Finšgar, Christoph Langhammer, Albin Pintar, 2023, izvirni znanstveni članek Povzetek: TiO2+Pt plasmonic solids with 1 wt% Pt and different TiO2 supports (anatase nanoparticles (TNP), polycrystalline nanorods (a-TNR) and single-crystal anatase nanorods (TNR)) were synthesized using the wet impregnation technique and tested as photo, thermal and photothermal catalysts in gas-solid and gas-liquid-solid reactions. Due to the different charges of the TiO2 support surfaces, Pt particles with different sizes, crystallinities and degrees of interaction with the TiO2 supports were formed during the synthesis. The heights of the Schottky barrier (SBH) were 0.38 eV for the a-TNR+Pt, 0.41 eV for the TNP+Pt, and 0.50 eV for the TNR+Pt samples, respectively. The low visible-light-triggered photocatalytic activity of the TNR+Pt catalyst toward the oxidation of water-dissolved bisphenol A (BPA) is attributed to its high SBH and active site deactivation due to the adsorption of BPA and/or BPA oxidation products. The highest photothermal catalytic H2-assisted NO2 reduction rate was expressed by the TNR+Pt catalyst. This can be ascribed to the presence of a narrow particle size distribution of small Pt particles, the absence of the Pt catalysed reduction of the TNR support at higher temperatures, and the lower rate of re-injection of “hot electrons” from the TNR support to the Pt particles.
Ključne besede: heterogeneous photocatalysis, titanium dioxide, plasmonic noble metal, platinum particles, visible light illumination, Schottky barrier height, bisphenol A, wastewater treatment, NOx abatement, air cleaning, microreactor, thermal catalysis, photothermal catalysis
Objavljeno v DiRROS: 23.06.2023; Ogledov: 361; Prenosov: 187
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3. Variability of generative offspring of field maple (Acer campestre L.) in nursery testingDalibor Ballian, Mirzeta Memišević Hodžić, Miroslav Murlin, Stjepan Kvesić, 2022, izvirni znanstveni članek Povzetek: Field maple (Acer campestre L.) is naturally distributed in most of Europe, with the exception of its northern parts. Field maple can serve as a valuable model for researching the sensitivity of its populations to habitat fragmentation, considering the lack of silvicultural treatments in its stands. The research aims to determine the interpopulation and intrapopulation variability of field maple populations from Bosnia and Herzegovina in the nursery test.The authors researched measured root collar diameter, height, observed forkness and calculated slenderness coefficient of the one-year-old generative material from 18 Bosnian-Herzegovinian populations of field maple, produced in the nursery of Žepče. The descriptive statistics and variance analysis was performed.All analyzed traits showed a high degree of intrapopulation as well as interpopulation variability, as confirmed by the analysis of variance. The highest average height was found in the provenance Bosanski Brod (46.08 cm) and the smallest in Bosanska Dubica (19.11 cm). Kreševo provenance had the highest average root neck dia-meter (8.27 mm) and Bosanska Dubica (5.24 mm) the lowest. A very low percentage of forkness (6.86%) was determined, and the values of the slenderness coefficient were acceptable for all provenances.The results indicate the need for further systematic research on this ecologically valuable species.
Ključne besede: field maple, variability, root collar diameter, height, forkness, slenderness
Objavljeno v DiRROS: 08.03.2023; Ogledov: 369; Prenosov: 169
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4. Artificial neural networks as an alternative method to nonlinear mixed-effects models for tree height predictionsMitja Skudnik, Jernej Jevšenak, 2022, izvirni znanstveni članek Povzetek: Tree heights are one of the most important aspects of forest mensuration, but data are often unavailable due to costly and time-consuming field measurements. Therefore, various types of models have been developed for the imputation of tree heights for unmeasured trees, with mixed-effects models being one of the most commonly applied approaches. The disadvantage here is the need of sufficient sample size per tree species for each plot, which is often not met, especially in mixed forests. To avoid this limitation, we used principal component analysis (PCA) for the grouping of similar plots based on the most relevant site descriptors. Next, we compared mixed-effects models with height-diameter models based on artificial neural networks (ANN). In terms of root mean square error (RMSE), mixed-effects models provided the most accurate tree height predictions at the plot level, especially for tree species with a smaller number of tree height measurements. When plots were grouped using the PCA and the number of observations per category increased, ANN predictions improved and became more accurate than those provided by mixed-effects models. The performance of ANN also increased when the competition index was included as an additional explanatory variable. Our results show that in the pursuit of the most accurate modelling approach for tree height predictions, ANN should be seriously considered, especially when the number of tree measurements and their distribution is sufficient.
Ključne besede: height-diameter models, national forest inventory, permanent sample plot, mixed forests, model comparison, principal component analysis
Objavljeno v DiRROS: 08.06.2022; Ogledov: 526; Prenosov: 224
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5. The effect of crown social class on bark thickness and sapwood moisture content in Norway spruceLuka Krajnc, Jožica Gričar, 2020, izvirni znanstveni članek Povzetek: The research study examined the effect of tree properties (crown social class, diameter at breast height (DBH), and tree height) on bark thickness (BT) and sapwood moisture content (SMC) in Norway spruce (Picea abies (L.) H. Karst.). Both examined variables were shown to be positively affected by DBH and tree height. The relationship between DBH and SMC varied among crown social classes, while the relationship between DBH and BT was relatively constant across crown social classes. Crown social class had a relatively small effect on BT and SMC, having a more pronounced effect on SMC than on BT. The relationship between tree height and BT did not vary across crown social classes, while the relationship between SMC and tree height was found to change slightly across crown social classes. Measurements of BT and SMC in the field are affordable, fast, and easy to use. Both variables could potentially be used to improve predictions of bark beetle attacks, as they reflect the physiological state of an individual tree.
Ključne besede: Picea abies, tree diameter, tree height, crown social class, phloem, sapwood
Objavljeno v DiRROS: 14.01.2021; Ogledov: 1231; Prenosov: 1038
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