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News of the National Academy of Sciences of Tajikistan.
Department of physical, mathematical, chemical, geological and technical sciences

Известия Национальной академии наук Таджикистана. Отделение физико-математических, химических, геологических и технических наук, №3(184), 2021 г.

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M.Ilolov , Kh.S.Kuchakshoyev , J.Sh.Rakhmatov
Fractional evolutionary stochastic differential equations
This article is devoted to the theory of solvability of stochastic evolutionary equations of fractional order perturbed by an additive term of the Balakrishnan white noise type. The results obtained here can find application in the analysis of various stochastic relaxation and diffusion processes in complex porous and fractal media.

Ключевые слова: white noise; Balakrishnan stochastic integral; fractional derivatives; Hilbert-Schmidt operator; resolvent operators' family.

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Variational Dirichlet problem for some classes of degenerate elliptic operators
The paper is devoted to review of results obtained in the Institute of Mathematics named after A.D.Dzhuraev of National Academy of Sciences of Tajikistan in last years on solvability of the variational Dirichlet problem for degenerate elliptic operators.

Ключевые слова: variational Dirichlet problem; elliptic operator; power degeneration; Fredholm solvability; smoothness of a solution; noncoercive sesquilinear form.

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Three linear overdetermined system Volterra type integral equation with singular domains
In this work in first time, three linear Volterra type over determined system integral equation with three singular domains is investigated. Obtained integral representation of the manifold solution with one arbitrary constant, in depend from that, in system (1) some equation is fundamental.

Ключевые слова: over determined system integral equation; jointly condition; singular kernels; representation manifold solution.

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Overview of results on application of gamma classifier
The γ-classifier is a mathematical triad consisting of a digital portrait (CP) of an object of study, a formula for distances between objects, and a precedent-based learning algorithm. Created in 2017, it has successfully expanded its scope of applications. In this work, together with the description of the classifier itself, the results obtained with its help are briefly presented.

Ключевые слова: machine learning; classifier; application; review of achievements.

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Achievements of astronomic science under the leadership of the National Academy of Sciences of Tajikistan
A brief historical background on the formation and development of astronomical and astrophysical science in the Republic of Tajikistan, from 1932 to the present, is given. The main achievements of the Institute of Astrophysics under the leadership of the National Academy of Sciences of Tajikistan and the contribution of the leading scientists of the Institute in its formation, development and achievement of the leading positions are shown. The prospects for the further development of astronomy and astrophysics in the republic are shown.

Ключевые слова: astronomy; astrophysics; Institute of astrophysics; observatory; academy; Tajikistan; collaboration; staff.

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A studying of relaxation processes, transport phenomena, elastic and dielectric properties of liquids and electrolyte solutions
A brief literature review of the theoretical methods of studying liquids and their solutions are given. Also, the initial kinetic equations obtained and solved by the Grad method for one- and two-particle distribution functions are briefly described. On the basis of these initial kinetic equations, the transfer phenomena, elastic, acoustic and dielectric properties of liquids and electrolyte solutions are investigated. Numerical calculations of these physical parameters are carried out and the results are presented in the form of tables and figures, as well as compared with the experimental data.

Ключевые слова: relaxation processes; transport coefficients; elastic modules; sound velocity and absorption; coefficients of specific electrical conductivity; dielectric permittivity and losses.

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Role of acid in the reaction of chemical conversion of protopectin to pectin polysaccharides
The generalized results of acid of hydrolysis-extraction of protopectins (PP) of the sunflower basket (SB) and beet pulp (SG), apple pomace (AP) and citrus peels (CP) in a wide range of pH, temperature 85°C, different duration of reaction, under static and dynamic conditions are presented. The hydrolyzate solution is separated according to the previously developed technique into fractions: microgel (MG), pectin substances (PS) and oligosaccharides (OS). Assuming that the hydrolysis-extraction process includes combinations of at least three types of reactions: hydrolysis of salts, hydrolysis of ester and glycosidic linkage. The probability of the response of each reaction was analyzed using the test outcome and indicators of the structure of PP decay components of the corresponding plant resources. High resulting values of the PS and the OS from beet pulp with high values of the HA remains and its degree of esterification - indicates a high probability of the decomposition reaction of polymer chains. Hydrolysis reaction of salt bonds is more characteristic for the decomposition of the PP and SB. The action of the acidity of the solution during the hydrolysis-extraction of pectin-containing raw materials is manifested not only in the catalytic process, but also in the extraction of calcium ions, which in turn depends on the primary structure of protopectin and their decay products.

Ключевые слова: protopectin; pectin substances; sunflower head residue; microgel; kinetics rate in flow; activation energy.

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I.N.Ganiev , J.H.Dzhayloev
Physical and chemical properties of aluminum alloy AlFe 2.18 with alkaline earth metals
The main regularities of changes in the heat capacity and thermodynamic functions (enthalpy, entropy and Gibbs energy) of the AlFe 2.18 aluminum alloy with calcium, strontium and barium, depending on the temperature and the amount of the alloying component, have been established. It is shown that with an increase in temperature, the heat capacity, entropy, and enthalpy of the AlFe 2.18 aluminum alloy with alkaline-earth metals increase, while the Gibbs energy of the alloys decreases. With an increase in the proportion of the alloying component in the AlFe 2.18 alloy, the entropy and enthalpy increase, and the value of the Gibbs energy decreases. It was revealed that with an increase in temperature, the oxidation rate of the AlFe 2.18 alloy with calcium, strontium and barium in the solid state increases. The oxidation rate constant is of the order 10kg / m. s. It was found that the oxidation process of the AlFe 2.18 aluminum alloy with calcium, strontium and barium is described by a hyperbolic equation. The potentiostatic method in the potentiodynamic mode at a potential sweep rate of 2 mV / s has established that the addition of alloying components up to 0.5 wt% increases the corrosion resistance of the initial AlFe 2.18 alloy by 25-35%. In this case, a shift in the corrosion potential of the initial alloy to the positive region is noted, and the potentials of pitting and repassivation - in the negative direction of the ordinate axis. When passing from alloys with calcium to alloys with strontium and barium, a decrease in the corrosion rate of alloys.

Ключевые слова: aluminum alloy AlFe 2.18; calcium; strontium; barium; heat capacity; thermodynamic functions; thermogravimetry; high temperature oxidation; oxidation rate; activation energy; potentiostatic method; anodic behavior; NaCl electrolyte environment.

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Research in the field of energy-intensive substances chemistry in V.I.Nikitin Institute of chemistry of NAS Tajikistan
The article systematizes the materials of the laboratory of chemistry of energy-intensive substances of the V.I.Nikitin Institute of Chemistry of the National Academy of Sciences of Tajikistan, published from 1970 to the present. Methods for obtaining boron- and aluminumhydrides of metals and aluminum hydride are considered. The physicochemical properties of boron and aluminum hydrides have been studied.

Ключевые слова: borohydrides; aluminohydrides; energy- intensive substances; aluminum hydride; Institute of Chemistry of the National Academy of Sciences of Tajikistan.

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H.M.Akhmedov , M.G.Khulmi , S.Rasulov
Analysis of the condition and prospects of the use of solar water pumps for irrigation and water supply
The analysis of the state and prospects of using solar technologies for irrigation and water supply is carried out. It is noted that irrigation as the main method of irrigation allows providing arable land with the required amount of water and contributing to an increase in agricultural productivity. The use of solar-powered water pumps in most cases can provide reliable, economical and environmentally sustainable energy for decentralized water and irrigation services. The authors believe that the sharp drops in prices for solar panels in recent years will provide new opportunities for their widespread use for irrigation and water supply, including in Tajikistan.

Ключевые слова: solar water pumps; irrigation; water supply; solar panels; photovoltaic stations; water lifting installations.

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Research in the field of physical and chemical basis of processing of uranium-containing materials and radioecology
The article discusses research in the field of uranium ores processing, uranium industry waste and in the field of radioecology. Basic technological schemes for obtaining uranium concentrates from various uranium-containing materials have been developed and an effective sorbent selection for uranium separation has been shown. Radioecological maps of the regions have been developed and radiation monitoring of the biological environment of Tajikistan has been carried out.

Ключевые слова: uranium-containing materials; radioecology; radioisotopes; tailing dump; radon; concentrate.