Granulometric Parameters of Solid Blueberry Fertilizers and Their Suitability for Precision Fertilization

For precise fertilization of blueberry plants, it is technologically the easiest and most suitable option to use a volumetric filling, for which it can be presumed that it is possible to precisely dose the fertilizer for each plant by grams. For setting up a volumetric filler, it is necessary to know parameters such as the size of the fertilizer particles and their bulk density. The aim of this research is to determine the granulometric parameters and their effect, which is done by measuring up three different fertilizers (SQM Qrop K, Memon Siforga, Substral): width, height, and length of 100 randomly selected fertilizer particles as well as the volumes and weights of 100 particles in 10 repetitions. According to the measurements, the average diameters of fertilizer particles were found as well as the average mass, volumes, and bulk density. A Mahr Digital Caliper 16EWRi 0–150 mm was used to measure the diameters of the fertilizer granules. A Yxlon FF35 computer tomograph was used to accurately scan particles. The analytical scale, Kern ABJ 220-4NM, was used to determine mass. The volumes were measured, using measuring glasses, with one having a maximum volume of 10 mL in 0.2 mL increments and another having a maximum volume of 100 mL in 1 mL increments. Descriptive statistics analysis was performed in Microsoft Excel. It turned out that the average diameters (3.68 vs. 3.64 vs. 4.29 mm) and bulk densities (0.928 vs. 0.631 vs. 0.824 g cm−3) of the three fertilizers differed far from each other, meaning that the given volume could be filled with different amounts of fertilizer. Equations between mass and weight were formed according to the measurements. As a result, it was found that a volumetric filler can be used for fertilizing blueberry plants precisely, but it demands adjusting the filler each time in the situation, which is defined by the variety of blueberry plants: their age, size, and health.

The problem of mathematical finite element modeling of inhomogeneous deformable solids using scanning

Introduction. In the mathematical finite element modeling, an average value of the mechanical characteristics of the deformable solid material is used. In aircraft, machine building, construction engineering, medicine and other fields, polymer composite materials and materials of natural origin are increasingly used. In the latter case, the actual change in the mechanical characteristics differs significantly from the averaged change; therefore, when using the averaged parameters to build and analyze finite element models, the results can be significantly distorted. This paper describes the creation of mathematical methods for studying changes in the mechanical characteristics of a material of inhomogeneous deformable solids. The results obtained in this way are used to construct finite element models and analyze their stress-strain state.Materials and Methods. Naturally occurring materials and composites are considered as inhomogeneous deformable solids. To study the changes in the mechanical characteristics of the material, a method was developed based on the use of two components: the pixel characteristics of raster images scanned by a computer tomograph and the experimental data of field tests of standard samples.Research Results. A complex of mathematical methods has been developed for modeling the interpretation of scanning raster images by a computer tomograph, which allows for the study of any complicated structures of real deformable solids. The results are used in the construction of finite element models of such bodies considering the heterogeneity of the mechanical characteristics of the material. The analysis of the stress-strain state of finite element models of test samples has proved the accuracy and convergence of the numerical solution of the finite element method in modeling the property of heterogeneity of the mechanical characteristics of the material.Discussion and Conclusions. The developed approach can be applied to any physical principles of scanning (X-ray, ultrasound, laser, etc.) and for any types of materials if the data obtained as a result of scanning is developed in the form of a digital (raster) image.