Regular monitoring of the D- and F-layers of ionosphere over Central Asia territory is being performed on the permanent basis starting year 2008 when one Very Low Frequency (VLF) receiver and two SuperSID receivers were provided to Uzbekistan IHY cite by Stanford University. The results obtained at Tashkent IHY (International Heliophysical Year) station are applied to earthquake electromagnetic precursors, lightning, and Solar flares and to ionospheric disturbances originating from gamma ray flares of Soft Gamma-Ray Repeaters. Regular monitoring of the D-layer of ionosphere over Central Asia territory has been performed on the permanent basis. Several Solar events are observed and the analysis has shown that there is simultaneous correlation between the times of change of amplitude of the waves and the Solar flares. Features of the lightning discharge generated by radio atmospherics are studied and its effectiveness in D-region ionosphere diagnostics is examined. We have mainly analyzed GPS derived TEC disturbances from two GPS stations located in Tashkent and Kitab, for possible earthquake ionospheric precursors. The solar and geomagnetic conditions were quiet during occurrence of the selected more than 30 earthquakes. We produced TEC time series over both sites and apply them to detect anomalous TEC signals preceding or accompanying the earthquakes. The results show anomalous enhancements which are examined in the earthquakes.
Success in cultivating cotton largely depends on the timing and quality of soil preparation for sowing and sowing, and the latter, in turn, depends on how it is carried out and on the perfect design of the machines. The aim of the study is to justify the shape of the ridges and the parameters of the moulder to the cotton seeder. The authors proposed a new technology for sowing with the simultaneous formation of ridges. The shape and parameters of the ridge are theoretically substantiated. When performing the shape of the ridge in the form of an isosceles trapezoid and, accordingly, with a height and width of the ridge surface of at least 100 mm and 160 mm, the seed bed is protected from flooding by rain streams. The design of the developed comb moulder to a cotton seeder for the implementation of the proposed technology is given. Theoretically substantiated the main parameters of the crest moulder. It was found that when the input edge of the moulder is 290-320 mm wide, the output edge is 160 mm, the angle of inclination of the side blade to the direction of movement is 20°, the length of the runner of the moulder is 203-215 mm, the height of the side blade is 100 mm and the angle of installation of the side blade to horizon 42-45° ensures highquality implementation of the technological process of formation of ridges. When sowing cotton seeds on the ridges with the simultaneous formation of the ridge, the seedlings of the plants increase, and the cotton yield increases compared to the smooth sowing method of 9.9%.
Ташкентский финансовый институт; к.ф.-м.н., доцент Д.А. Ходжаев, Ташкентский институт ирригации и мелиорации Аннотация. В работе приводятся численный метод и алгоритм решения задач динамики вязкоупругих тонкостенных элементов конструкций переменной толщины. Уравнения движения относительно прогибов описываются интегро-дифференциальными уравнениями (ИДУ) в частных производных. При помощи метода Бубнова-Галеркина, основанного на многочленной аппроксимации прогибов, задача сводится к исследованию системы обыкновенных ИДУ, где независимой переменной является время. Система ИДУ решается предложенным численным методом, на основе которого описан алгоритм численного решения и создана программа на алгоритмическом языке Delphi. Исследование нелинейных колебаний тонкостенных элементов конструкции с учетом переменной толщины в геометрической нелинейной постановке позволило выявить ряд механических эффектов. В зависимости от физико-механических и геометрических параметров рассмотренных вязкоупругих тонкостенных элементов конструкций даны рекомендации по использованию жесткости системы. Ключевые слова: тонкостенные конструкции; переменная толщина; вязкоупругость, неоднородность; метод Бубнова-Галеркина; интегро-дифференциальные уравнения Введение В прикладных задачах механики деформируемых систем приходится встречаться с процессами, при описании которых необходимо оперировать имеющими разрывы величинами, различными по своему физико-механическому содержанию. В последнее время стало появляться все больше работ, посвященных результатам исследований критического состояния, колебаний и напряженно-деформированного состояния (НДС) конструкций с физико-механическими особенностями разрывного типа, т. е. конструкций cо ступенчато-переменной толщиной, с армированиями, неоднородностями структуры, местными включениями в виде сосредоточенных масс и отверстий, либо пониженной жесткости в виде ребра с учетом изотропных и анизотропных свойств материала [1-7].
A method for dynamic calculation of a box-like structure, consisting of interconnected longitudinal and transverse plate and beam elements is developed. The problem is posed of spatial vibrations of the box-like structure of a building under dynamic impact determined by its base motion according to a sinusoidal law. It is assumed that the external load-bearing walls of the building, perpendicular to the direction of the seismic effect, work on transverse bending only. The interior panels, located in the direction of external impact, are subjected to tension-compression and shear in their planes. Equations of vibrations of the points of panels, box beams, boundary and initial conditions of the problem are given. In the areas of butt joints of panels, full contact conditions are set to ensure the equality of displacements and stresses. Within the framework of the finite difference method, a methodology was developed for dynamic calculation of box-like structures. Numerical results of stresses over time in the hazardous areas of the box were obtained. The laws of changes in the maximum stress values in characteristic sections of the panels are graphically presented as a function of time.
The problems of oscillations of a viscoelastic cylindrical panel with concentrated masses are investigated, based on the Kirchhoff-Love hypothesis in the geometrically nonlinear statement. The effect of the action of concentrated masses is introduced into the equation of motion of the cylindrical panel using the δ function. To solve integro-differential equations of nonlinear problems of the dynamics of viscoelastic systems, a numerical method is suggested. With the Bubnov–Galerkin method, based on a polynomial approximation of the deflection, in combination with the suggested numerical method, the problems of nonlinear oscillation of a viscoelastic cylindrical panel with concentrated masses were solved. Bubnov–Galerkin’s convergence was studied in all problems. The influence of the viscoelastic properties of the material and concentrated masses on the process of oscillations of a cylindrical panel is shown.
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