A Practical Guide to Spectrogram Analysis for Audio Signal Processing

The paper summarizes spectrogram and gives practical application of spectrogram in signal processing. For analysis, finger-snapping is recorded with a sampling rate of 441000 Hz and 96000 Hz. The effects of the number of segments on the Power Spectral Density (PSD) and spectrogram are analyzed and visualized

Dynamic calculation of nonlinear oscillations of viscoelastic orthotropic plate with a concentrated mass

Plates, panels and shells made of composite material with fixed objects in the form of an additional mass have found a wide use due to their viscoelastic and strength properties. An analysis of their dynamic behavior indicates a significant effect of inhomogeneity of an associated mass type on their strength. The problem of oscillations of a viscoelastic orthotropic rectangular plate with an associated mass is considered according to the Kirchhoff-Love hypothesis in a geometrically nonlinear statement. This problem is reduced to solving the systems of nonlinear integro-differential equations with singular relaxation kernels, solved by the Bubnov-Galerkin method in combination with a numerical method based on the use of quadrature formulas. The numerical values of the approximate solution have been calculated in the Delphi programming environment. At wide range of changes in physicomechanical and geometrical parameters, the behavior of the plate has been studied. The effect of viscoelastic and inhomogeneous material properties, concentrated mass and their location on the oscillatory process of a rectangular plate is shown

Vibrations of a geometrically nonlinear viscoelastic shallow shell with concentrated masses

Shell structures are widely used in various fields of technology and construction. Often, they play the role of a bearing surface with assemblies, overlays, and aggregates installed on them. At the same time, in solving various problems, such attached elements are considered as the elements concentrated at the points and rigidly connected. Vibrations of an orthotropic viscoelastic shallow shell with concentrated masses in a geometrically nonlinear setting are considered. The equation of motion for a shallow shell is derived based on the Kirchhoff-Love theory. The traditional Boltzmann-Volterra theory is used to describe the viscoelastic properties of a shallow shell. The effect of concentrated masses is taken into account using the Dirac delta function. Using the polynomial approximation of the deflections of the Bubnov-Galerkin method, the problem is reduced to solving a system of ordinary nonlinear integro-differential equations with variable coefficients. In the calculations, the three-parameter Koltunov-Rzhanitsyn kernel was used as a weakly singular relaxation kernel. A numerical method was used to solve the resulting system that eliminates the singularity in the relaxation kernel. The problem of nonlinear vibrations of an orthotropic viscoelastic shallow shell with concentrated masses is solved. The influence of concentrated masses and location, properties of the shell material, and other parameters on the amplitude-frequency response of the shallow shell vibrations is investigated

Economically Valuable Traits of Alfalfa Plants in The Variety Testing Nursery

The article presents the three-year results for 2018-2020 of studies on height, leafiness of plants, protein content, as well as hay yield in alfalfa samples in the nursery of the 2018 sowing variety test. The studied accessions and the standard variety Tashkent-1 almost did not differ in plant height the difference was only 1-2 cm. plants was higher than the standard by 3-2cm. The highest leafiness of plants was in samples C-3646 (variety Zia, USA), C-3327 (I.o. Prima, France) and C-3649 (F2 Tashkent-721x group of varieties) 48.1%, 47.5% and 46.4% respectively, which exceeded the standard variety. The high protein content of hay enhances the nutritional quality of alfalfa. According to this indicator, the data obtained show that the varieties S-3649, S-3646 and S-3647 had superiority over the standard variety Tashkent-1 (17.85%) by 1.03-1.32%. According to the total hay yield for two years, samples S-3647 and S-3649 were 108.6% and 106.1% higher in comparison with the standard variety (129.0 c/ha). And in the rest of the samples, the hay yield was lower than that of the Tashkent-1 variety. According to the combination of a set of traits, samples C-3647 (M.o. from variety 2711x group of varieties) and C3649 (F2 Tashkentskaya-721x group of varieties) are of the greatest interest for breeding

Dynamic analysis of an orthotropic viscoelastic cylindrical panel of variable thickness

The intensive development of the modern industry is associated with the emergence of a variety of new composite materials. Plates, panels, and shells of variable thickness made of such materials are widely used in engineering and machine building. Modern technology for the manufacture of thin-walled structures of any configuration makes it possible to obtain structures with a given thickness variation law. Such thin-walled structures are subjected to various loads, including periodic ones. Nonlinear parametric vibrations of an orthotropic viscoelastic cylindrical panel of variable thickness are investigated without considering the elastic wave propagation. To derive a mathematical model of the problem, the Kirchhoff-Love theory is used in a geometrically nonlinear setting. The viscoelastic properties of a cylindrical panel are described by the hereditary Boltzmann-Volterra theory with a three-parameter Koltunov-Rzhanitsyn relaxation kernel. The problem is solved by the Bubnov-Galerkin method in combination with the numerical method. For the numerical implementation of the problem, an algorithm and a computer program were developed in the Delphi algorithmic language. Nonlinear parametric vibrations of orthotropic viscoelastic cylindrical panels under external periodic load were investigated. The influence of various physical, mechanical, and geometric parameters on the panel behavior, such as the thickness, viscoelastic and inhomogeneous properties of the material, external periodic load, were studied

Effect of irrigation-induced erosion on the degradation of soils in river valleys of the alpine Pamir

© 2015, Pleiades Publishing, Ltd. Results of a study were analzyed, which was conducted on the arable stony alpine soils in the Gunt River valley and the upper Panj River. Such soils are occurring in different regions of the Western Pamirs. The physicochemical properties of the soils were studied using conventional methods, and the degradation rate of the soil cover was determined using the radiocesium method. Low contents of humus (2–3° with furrow irrigation, is the main anthropogenic factor of soil degradation. The lower content of humus in the soils of the Panj River valley is due to the larger portion of slopes >3° with furrow irrigation, on which also maximum rates of irrigation-induced erosion (>30 ha/year) were observed

Modern possibilities of optical reconstructive surgery in patients after removal of the iridociliary zone tumor

Choroid neoplasms account for two-thirds of all intraocular tumors, of which 23% are tumors of the iris and ciliary body, and the rest are choroidal tumors. After removing the tumor of the iridociliary zone (ICZ) it is necessary to perform optical reconstructive surgery to reduce light aberrations and increase visual functions.Purpose. To identify key features of the complex rehabilitation of patients after removal of the ICZ tumor.Material and methods. The clinical and functional results of the complex rehabilitation of 12 patients (12 eyes) aged from 35 to 84 years (average 66 years) were studied at least 1 year after removal of the ICZ tumor. The area of the iris defect before the reconstructive surgery ranged from 15 to 55%. Preoperative uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) were 0.26±0.19 (from 0.01 to 0.6) and 0.46±0.22 (from 0.1 to 0.8) respectively. All patients underwent phacoemulsification of cataract and implantation of the irislens diaphragm.Results. After the reconstructive surgery, UCVA and BCVA increased: 0.5±0.17 (from 0.2 to 0.7) and 0.61±0.27 (from 0.3 to 0.9) respectively. Undesirable optical effects were decreased, and patients were satisfied with the cosmetic result.Conclusion. The presented algorithm of optical reconstructive surgery after removal of the ICZ tumor creates necessary conditions for increasing postoperative functional results and improving the quality of life of these patients

Melatonin level as a risk factor for age-related macular degeneration

Background. The current trend towards an increase in age-related macular degeneration (AMD) incidence rate in the population, including the working-age population, with a possible loss of professional activity, indicates the need for early preclinical identification of risk groups, timely prevention and treatment. In the prevention and treatment of AMD, the prospect of using melatonin is being actively discussed.Aim: to analyze serum and tear fluid levels of melatonin in patients with AMD and study their correlation with risk factors.Materials and methods. In the course of the study, two groups were formed: the main group - patients with non-exudative AMD and senile cataract (n = 40) and the reference group - conditionally healthy patients without AMD and cataract (n = 20). Patients of both groups were surveyed to identify risk factors for AMD. The content of melatonin in blood serum and lacrimal fluid was determined by enzyme-linked immunosorbent assay using the Melatonin ELISA Kit (USA).Results. In the course of the study, it was found that the concentration of melatonin in blood serum and tear fluid in patients with AMD was significantly lower than in patients of the reference group (p <0.05). Serum and tear fluid melatonin levels depend on the following factors: age, body mass index (BMI), arterial hypertension, eye color, insomnia, and night work. It is possible that the local determination of melatonin in the lacrimal fluid can be a biomarker in the determination of ophthalmic pathological conditions.Conclusion. The obtained results can be used as recommendations for clarifying individual regimens for the use of melatonin, especially in the treatment of patients with AMD