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Iskalni niz: "ključne besede" (correlation) .

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1.
Experimental study of the burning behavior and key parameters of gasoline pool fires with different ullage heights
Jinlong 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: 152; Prenosov: 34
.pdf Celotno besedilo (1,51 MB)
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2.
Statistical approach to interpretation of geochemical data of stream sediment in Pleše mining area
Simona Jarc, 2022, izvirni znanstveni članek

Povzetek: The Ba, Pb and Zn ore deposit Pleše near Ljubljana is one of the formerly productive mines. The stream sediments were sampled and analysed by XRF to establish the effect of grain size, mineralization, and downstream location of sampling sites on geochemical composition based on various statistical analyses. Statistical analyses of the geochemical data confirm the impact of mineralization. The parametric t-test, non-parametric Mann-Whitney test and cluster analysis showed only minor differences in the geochemical composition of the samples with different grain sizes (< 0.063 mm and 0.063-2 mm). The parametric and non-parametric correlation coefficients as well as cluster analysis indicate that the contents of Si, Al, K, Rb, and Fe are associated with weathered rock forming minerals such as micas, and clay minerals, whereas Nb and Zr are associated with minerals resistant to weathering. Ca and Mg are associated with carbonates. S, Ba, Sr, Pb, Zn, and Mn indicate local mineralization with sulphates and sulphides. The results of the t-test and analysis of variance, Mann-Whitney tests and Kruskal-Wallis ANOVA of the groups established by the cluster analysis confirm that the contents of Ba, Pb and Sr have a statistically significant influence on the classification of the cluster group - i.e., the influence of sediment mineralization. There are no differences in elemental contents in the sediment samples downstream. The statistical approach to evaluate the geochemical data has proven useful and provides a good basis for further interpretation.
Ključne besede: ANOVA, t-test, correlation, cluster analysis, XRF, mineralization
Objavljeno v DiRROS: 18.01.2023; Ogledov: 426; Prenosov: 200
.pdf Celotno besedilo (1,01 MB)
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3.
Ekstremne korelacije
Anton Cedilnik, 1991, izvirni znanstveni članek

Povzetek: In the article we define a quantity which measures the quality of the approximation of a function, given by a table, with a function from a certain family D of nonconstant functions. For this purpose one has to find the infimum and the supremum of the set of correlation coefficients between the given function and functions from D.We do this for the family of all nonconstant functions and for the family of growth functions.
Ključne besede: mathematics, approximations, mathematical programming, forestry, extremal correlation, nonlinear programming
Objavljeno v DiRROS: 12.07.2017; Ogledov: 4388; Prenosov: 1855
.pdf Celotno besedilo (517,92 KB)

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