Distance-based vegetation indices computed by SAGA GIS: A comparison of the perpendicular and transformed soil adjusted approaches for the LANDSAT TM image

Landsat-TM of 2001 covering Iceland (15.5°W-21°W, 64.5°N-67°N) was processed using SAGA GIS for testing distance-based Vegetation Indices (VIs): four approaches of Perpendicular Vegetation Index (PVI) and two approaches of Transformed Soil Adjusted Vegetation Index TSAVI. The PVI of vegetation from the soil background line indicated healthiness as a leaf area index (LAI). The results showed that the reflectance for vegetation has a linear relation with soil background line. Four PVI models and two TSAVI shown coefficients of determination with LAI. The dataset demonstrate variations in the calculated coefficients. The mode in the histograms of the PVI based on four different algorithms show the difference:-7.1,-8.36, 2.78 and 7.0. The dataset for the two approaches of TSAVI: first case ranges in 4.4.-80.6 with a bell-shape mode of a histogram (8.09 to 23.29) for the first algorithm and an irregular shape for the second algorithm with several modes starting from 0.11 to 0.2 and decreasing to 0.26. SAGA GIS permits the calculation of PVI and TSAVI by computed NDVI based on the intersection of vegetation and soil background. Masking the NIR and R, a linear regression of grids was performed using an equation embedded in SAGA GIS. The advantages of the distance-based PVI and TSAVI consists in the adjusted position of pixels on the soil brightness line which refines it comparing to the slope-based VIs. The paper demonstrates SAGA GIS application in agricultural studies.

Zero “Background” Line for Iron Alloys Samples Dilatographs Decoding

The dilatographs decoding variant was carried out on the basis of comparison with the zero "background" line for heating the metallic materials samples. The line is formed taking into account the features of the change in the true values ​​of the linear coefficient of thermal expansion. It has been calculated on the dilatographs basis. The experimental fact was revealed, which is in contradiction with general metal science concepts concerning dilatometric results of recrystallization in materials with polymorphism. The expected result of the thermal change in the sample dimensions has the opposite sign with respect to the experimental result in the recrystallization temperature intervals. This requires careful theoretical and experimental analysis. In our opinion, a possible reason for the discrepancy is the fact that the size of the atoms changes during recrystallization due to the electron orbitals hybridization of iron atoms, due to a change in temperature and intracrystalline pressure.

Cold H I in turbulent eddies and galactic spiral shocks

H I 21cm-line self-absorption (HISA) reveals the shape and distribution of cold atomic clouds in the Galactic disk. Many of these clouds lack corresponding CO emission, despite being colder than purely atomic gas in equilibrium models. HISA requires background line emission at the same velocity, hence mechanisms that can produce such backgrounds. Weak, small-scale, and widespread absorption is likely to arise from turbulent eddies, while strong, large-scale absorption appears organized in cloud complexes along spiral arm shocks. In the latter, the gas may be evolving from an atomic to a molecular state prior to star formation, which would account for the incomplete HISA-CO agreement.

Residual Stress Error Introduced by Truncated Patterns: Prediction and Correction

The truncation of diffraction patterns in residual stress determination is often observed for broadened peaks when the 2θ acquisition range is not wide enough. The loss of information effects induced can either be traduced by a bad estimation of the background line, for the methods including a background subtraction, or a restriction of the analysis area for the others. In that borderline case, the results obtained by all methods with theirs specific parameters, developed to estimate the peak localisation are rather distributed in a wide range of stress values. In this paper we propose to review and to test some of the most common methods for stress evaluation (parabola, middle of chord, centred centroïd, asymmetrical pseudo-Voigt fitting). A separate study is made concerning error introduced on the 2θ peak position and on the final stress value estimated. For the parabola method, an analytical expression including some approximations such as the peak shape and its full width at half maximum is then given for the prediction and the correction of these errors. This study is sponsored by PSA PEUGEOT-CITROËN, RENAULT and SNECMA.

Correction of X-ray Diffraction Profiles Measured by PSPC System

When an x-ray diffraction profile Is measured for stress analysis or profile analysis by the use of a linear (straight line) position sensitive proportional counter (PSPC) , a convex-type background line is obtained because of the geometrical problem and the absorption of x-rays. Such phenomenon is remarkable when a wide angular range is set on a linear PSPC and it is, in particular, necessary to correct with a straight background for accurate measurement of diffraction angle or half-value breadth of the broadened diffraction profile.

Rapid Spectrophotometric Method for Determination of Chlorogenic Acid in Leaf Tobacco

A simple, rapid, quantitative procedure has been devised to measure chlorogenic acid in a 75% aqueous ethanolic extract of ground tobacco. The absorbance of the extract at 330 mμ is directly proportional to the concentration of chlorogenic acid, provided a suitable background line is drawn to correct for interfering nonpolyphenolic substances. Analysis of a series of eight bright tobacco samples has shown large variations among leaves from different stalk positions, with a very definite trend toward higher chlorogenic acid content nearer the top of the stalk. The chlorogenic acid content of burley tobaccos appears to be extremely low. The precision of replicate analyses has been found to be ± 3%, relative, for virtually all samples analyzed. Many vary less than 1% between duplicate determinations.