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  • Author or Editor: L. Csorba x
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Central leader and vase form tree models were built using Finite Element Modelling (FEM). Their main characteristics were chosen to be the same. To get comparable results to real values, acceleration versus time curves of the two types of real trees were processed using FFT method to determine their natural frequencies. The natural frequencies measured on real trees and calculated for the models have shown good similarity. The models were virtually exposed to the effect of horizontal forced vibration in the frequency range of 0–20 Hz. Acceleration-frequency curves were calculated and drawn to find the best frequency values for the highest accelerations and also to see their differences in the limb. For the same purpose, the direction of shaking was also changed. It was found that for the central leader limb shape multidirectional shaking would bring uniform detachment, while for the vase form trees, even the unidirectional shakers are appropriate. Real trees were also shaken and their acceleration-frequency curves were compared with the values of the FEMs. The resultant good similarity proves the ability of the models. The acceleration values achieved in the vase form models were much higher than for the central leader type. The acceleration-frequency curve of the shaker unit can be used to find the best frequency for shaking.

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The hyperspectral imaging spectroscopy is a promising future tool in the field of optical remote sensing and it creates new perspective for modern information management in site specific agricultural production. One can determine quantitative relationships between the environmental and physiological parameters of vegetation cover and the soil quality parameters as well as the features of the reflectance spectra by the newgeneration data monitoring and sampling method. These reflectance spectra have characteristics of the different crops and provide with the possibility of accurate classification and detection. The objective was to present the technological capabilities of hyperspectral imaging and show some exprimental results of nutrient sensitive changes in the winter wheat spectra. There were found two characteristic wavelength ranges: the 500 to 800 nm for wheat kernel samples and the 1650 nm to 1800 nm for wheat ear samples where fertilizer treatments showed definite trend on the basis of the normalized reflectance spectra.

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