The topics included in the scope primarily emphasize understanding the physics underlying modern technology. Approximate measurements of natural background radiation in the atmospheric surface layer of the Almaty region. Due to this fact, the problem of studying the radiation distributions in the Earth's atmospheric surface layer is urgent.
The preliminary results of measurements of significant disturbances of EEVA by radon did not reveal. An altitude dependence of changes in the natural radiation gamma and beta background of the surface. Measurement of the content of radon and thoron in samples, Publishing House ВВМ, Saint Petersburg, 2020, 38p.
We obtain the numerical results of the ground state energies of 41Ca and 41Sc from Eq. Bound state solution of the Schrodinger equation for the modified Kratzer potential plus screened Coulomb potential // Indian J. Any l state solution of the Schrodinger equation in interaction with Hellmann generalized Morse potential model // Karbala Intl.
Optical properties of dextran-stabilized silicon nanoparticles in aqueous medium
The colloidal stability of Si-NPs in aqueous media was analyzed using a dynamic light scattering (DLS) method with a Zetasizer Nano ZS DLS analyzer (Malvern, UK), which was also used for measurements of the electrokinetic zetta potential ( ZP) of Si-NPs. Measurements of DLS and ZP confirm the presence of dextran on the surface of Si-NPs dispersed in the dextran solution. The increase of the hydrodynamic size of Si-NPs in the dextran solution compared to that for initial Si-NPs may also be related to agglomeration of the former NPs.
The sharp drop in the pH dependence of ZP for Si-NPs in dextran solution and its smoother behavior in the case of initial Si-NPs can be explained by different parameters of the surface groups, which are modified in the presence of dextran molecules. . Taken together, these observations provide strong evidence that the surfaces of Si-NPs are actually covered with dextran molecules in aqueous solution. Since Si-NPs in this spectral region are characterized by a large absorption cross-section, the extinction value can be approximately equal to the absorption.
While the spectrum for the initial Si-NPs exhibits a shoulder in the region of 400–600 nm, which can be attributed to Mie scattering from individual Si-NPs of about 100 nm in size [3], the absorption spectrum of Si dextran-coated NPs show a smoother decrease in absorption in the investigated spectral region. To study the dissolution kinetics of Si-NPs in the aqueous medium, the integral absorption intensity in the range of 400-600 nm is calculated and analyzed. The absorption intensity (Fig. 4) decreases with the deposition time of Si-NPs in aqueous environments.
It is noteworthy that half of the Si-NPs coated with dextran are stable in a solution with any pH level for at least 300 hours (see Fig.4b). This fact indicates a high level of the surface stabilization of Si-NPs by dextran molecules. The dissolution rate of dextran-doped Si-NPs does not depend on pH and is significantly lower than one for the initial Si-NPs.
The dissolution kinetics of uncoated Si-NPs in an aqueous medium strongly depends on the pH of the solution. The addition of dextran to the solution can significantly slow down the dissolution of Si-NPs, which is related to the coating of these NPs with a polymer shell.
Simulation of non-isothermal liquid sprays under large-scale turbulence
Liquid fuel is injected through a nozzle in the center of the lower part of the combustion chamber. The initial temperature of the gas in the combustion chamber was 700 K, the fuel was injected at 300 K. The pressure in the combustion chamber was 80 bar, the injection speed of the liquid fuel was 250 m/s.
In this work, the simulation results of the processes of atomization, dispersion and combustion of liquid fuels in a cylindrical combustion chamber are presented. The results of a numerical simulation of dodecane combustion depending on the initial temperature of the oxidizer in the combustion chamber are presented. During the combustion of dodecane, the concentration of carbon dioxide formed reaches high values.
From the analysis of the curves in Figures 3 and 4, it can be concluded that for dodecane, the optimal initial temperature of the oxidizer in the combustion chamber is 900 K. At the instant of time t=2.5 ms, dodecane droplets are concentrated in a small area along the width of the combustion chamber. At this time, on the axis of the chamber during the combustion of dodecane, fuel vapors rise up to 3.8 cm along the height of the combustion chamber.
Figures 8-9 show the results of numerical simulations of the distribution of combustion products and oxygen concentration on the chamber axis. The graphs of the distribution of the reaction products at the 3 ms time point are shown. By analyzing this graph, one can be sure that the greatest amount of oxygen is concentrated in the torch core during the combustion of the liquid fuel. a) t=2.5 ms b) t=3 ms.
Analysis of the figure shows that the maximum amount of carbon dioxide for dodecane on the axis of the combustion chamber, the concentration of carbon dioxide reaches a value equal to 0.103878 g/g. In this way, we presented the numerical study of the influence of the initial temperature of the oxidant on the combustion of dodecane in this paper. It has been shown that for the investigated type of fuel (dodecane), the best initial temperature of the oxidizer in the combustion chamber is 900 K.
3D modeling of heat transfer processes in the combustion chamber of the TPP boiler // News of the National Academy of Sciences of the Republic of Kazakhstan.
Influence of an external electric field
An impermeable sphere of radius r0 << λi placed in the center of this domain plays the role of the solid particle, where λi is the ion Debye length. We use the dimensionless parameters in the calculations, i.e. the dimensionless charge of the dust particle Q and the dimensionless external electric field E given by the expressions:. The charge of the dust particle is calculated based on the condition that the currents of ions and electrons to the surface are equal.
For small values of the external electric field, the spatial distributions of the electron density ne(r,θ), the ion density ni(r,θ) and the electric potential U(r,θ) deviate weakly from spherically symmetric (r and θ are spherical.coordinates). In this paper we have considered that the electron temperature is a function of the reduced external electric field E/N. We use the dependence of the average electron energy <ε> = 3/2kTe versus the reduced electric field E/N calculated with the help of the BOLSIG+ solver [21] (see Figure 1) to obtain the Te(E/N) dependence.
The purpose of the calculations is to determine the role of the mean free path li of the ions on the charge of dust particles at the same electron temperature. The value of the reduced electric field strength for all curves is the same E/N = 37 Td. It is interesting to note that the right parts of the space charge density and electric potential deviate substantially for different ion-averaged free paths and the right parts almost coincide with each other.
The greater the mean free path of the ion, the greater the amplitude of its oscillations. The dipole moment of the "dust particle - ion cloud" should also be revised for the same electron energy for different li. Thus, taking into account the energy of the electrons does not affect the dependence of the anisotropy of the ion cloud on the magnitude of the external field.
The paper presents the results of numerical modeling of plasma parameters around an isolated charged dust particle under the action of an external electric field. the developed computational model was extended by taking into account the dependence of the mean electron energy on the reduced electric field strength. As a result of the calculations, the dependences of the self-consistent spatial distributions of the density of electrons and ions, the electric potential around the dust particle for different values of the mean free path of the ion and the reduced electric field were obtained.
Detecting the Sun’s active region using image processing techniques
It simply slides the template image over the input image (as in 2D convolution) and compares the template and the input. Figure 1 (right panel) shows the brightest pixel location identification at AIA 335 Å wavelength obtained using naive and robust methods. This function then takes our grayscale image and, with the smallest and largest intensity values, finds the pixel position and (x, y) value, respectively.
In the Figure 2 (right panel) shown the brightest pixel location identification in AIA 335 Å wavelengths obtained by using naive and robust methods. Then we will call cv2.minMaxLoc again to find the brightest pixel in the picture. We can average over a wider range of pixels by using a larger radius - thus simulating larger regions of the image.
Figure 3 (right panel) shows the brightest pixel location identification in AIA 335 Å wavelengths obtained using naive and robust methods. We are interested in the brightest part of the image, namely the optic nerve center. Figure 4 (right panel) shows the brightest pixel location identification in AIA 335 Å wavelengths obtained using naive and robust methods.
If the radius is too small, we won't be able to find larger, brighter parts of the image. Figure 5 (right panel) shows the brightest pixel location identification in AIA 335 Å wavelengths obtained using naive and robust methods. If we take too small a value, we will soften it. the effects of the average and miss the larger, brighter areas.
The non-homological nature of solar diameter variations //. Solar diameter measurements and variations // Solar Phys. Statistical study of the spatio-temporal distribution of solar flare precursors associated with major flares // Monthly Notices of the Royal Astronomical Society.
