of National Academy of Sciences
of Tajikistan

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

Известия Академии наук Республики Таджикистан. Отделение физико-математических, химических, геологических и технических наук, №4(181), 2020 г.

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Exact estimates of speed of convergence of hyperbolic private sums the double fourier series in general orthogonal polynomials
In work the exact upper bounds approximation of functions two variables hyperbolic partial the sums of a double number of Fourier on the general orthogonal polynomials on some classes of functions are calculated.

Ключевые слова: best approximation; modulus of continuity; sums Fourier; orthogonal polynomials; inequalities.

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On the solution of one class of generalized systems metaparabolic equations of the second order on the plane with given mains parts
In the work we investigate the existence of problem and finding bounded and doubly periodic solutions for a class of metaparabolic systems of the second order equations on the plane with given main parts.

Ключевые слова: doubly periodic solution; metaparabolic systems of equations; generalized solution; solution with the poles.

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Neuman problem for general elliptic system of fourth order differential equations
In this paper we study Noethericity and index of the Neumann problem for a general elliptic system of fourth-order differential equations. Investigation of this problem is carried out by the method of reduction of system the equivalent two-dimensional singular equation on a bounded domain.

Ключевые слова: singular integral operation; symbol operator; the index of operator; Noetherian operators; elliptical system.

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About recognition of the author of the text based on the frequency of single and multi-signed ɑβ-codes of words
The article solves the problem of recognizing the authors of works for classical and modern poetry, as well as modern prose. The works are compared with a digital portrait characterized by the distribution of the frequency of single-valued and multivalued ɑβ -codes in them. The effectiveness of the application of the classifier for the identification of the authors of works is confirmed.

Ключевые слова: Tajik language; single-valued and multi-valued ɑβ-codes; classifier.

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G.I.Kokhirova , P.B.Babadzhanov , U.H.Khamroev , A.I.Zhonmuhammadi
Asteroids associated with the Librid-Lupid meteoroid stream
The results of finding of asteroids associated with the meteoroid stream producing the Northern and Southern Librid-Lupidmeteor showers are presented. Revealed association points to a cometary nature of the asteroids that are moving within the stream and very probably represent extinct fragments of a comet-progenitor of the stream.

Ключевые слова: comet; asteroid; extinct comet; meteoroid stream; meteor shower; orbit; radiant.

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M.M.Gulomov , S.S.Dzhumaev , M.M.Safarov
The effect of single-wall carbon nanotubes on the change in the thermal conductivity of isobutane at different temperatures and pressures (2.5 MPa)
This work presents the results of experimental and numerical calculation of the thermal conductivity coefficient of chemical frequent isobutane without the addition of single-walled carbon nanotubes (SWCNT) and with the addition of up to 2.5% SWCNT in the temperature range (293-660) K and pressures from 0.101 to 2.5 MPa and concentration (0 - 2.5%) SWCNT. To measure the thermal conductivity of the systems under study (isobutane + SWCNT), we used an experimental setup developed on the basis of the method of a reasonable thermal regime (Professor I.F. Galubev) of the first kind. To determine the numerical calculations of the thermal conductivity of the samples under study, the Einstein model was applied. The total relative error in the measurement of the thermal conductivity of solutions, liquids of the said installation at a confidence level of 0.95 is 3.5%, and the error of numerical calculations depends on the error in determining the initial data. Establishment that with increasing temperature, the thermal conductivity of nano-fluids of the system (isobutane + osunt) decreases, and an increase in external pressure leads to an increase in the thermal conductivity of the command + solutions. Using the law of thermodynamic similarity and experimental data, we obtained empirical dependencies that allow an incorrect experiment to determine the thermal conductivity of the samples under study at different temperatures and pressures.

Ключевые слова: liquid isobutane; single-shift carbon nanotubes; cylindrical bicalorimeter; regular thermal regime of the first kind; refrigerant; temperatures; pressures and concentration.

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I.N.Askerzade , N.Kartli , H.B.Yildirim
Frustration effect on the critical current of low inductance DC SQUID on Josephson junctions based on many-band superconductors
The calculation of the critical current of low inductance dc Supercoducting Quantum Interference Device (DC SQUID), when one of Josephson junctions based on frustrated many-band superconductor is presented. It is shown that behavior of DC SQUID is similar to case of Josephson junction with - peculiarity. Increasing of the amplitude of current in the second channel (frustration parameter), causes increasing of critical current of low inductance DC SQUID.

Ключевые слова: Josephson junction; many-band superconductors; frustration effect.

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D.A.Turaev , A.A.Toirov , D.A.Mirzoev
Concentrational dependence of porosity degree of the InP semiconductor for electrochemical anode treatment
To obtain the structure of nanopores, an electrochemical anode treatment of indium phosphide monocrystals based on hydrofluoric and hydrochloric acids, as an electrolyte, was performed. It was studied that the nanopores formed in the crystal structure of indium phosphide can affect its electrical and optical properties. Electronic devices based on porous InP can be easily integrated with other semiconductor devices.

Ключевые слова: porous structure; Indium Phosphide; electrochemical anode treatment; electronic devices.

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S.F.Odinaev , F.Rahimi , Kh.Kh.Muminov , V.L.Romodanov , M.Sh.Imom
Determination of measured informative parameters of the U content in fuel assembly control units of nuclear reactors
In this work the determination of the informative parameters of the U content in uranium samples with different sizes is considered. Various sizes have been identified that provide the best setting for large and small retarder installations

Ключевые слова: heat-extensive assembly; fissile materials; pulsed neutron generator; nondestructive analysis.

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M.Sh.Imom , Kh.Kh.Muminov , V.L.Romodanov , F.Rahimi , S.F.Odinaev
Digital method for determining the ratio of neutron pulses to gamma quantum pulses for various scintillator loads
The paper investigates the ratios of the number of neutron responses and responses of gamma quanta at various loads of the scintillation path. An analysis of the scintillation responses of neutrons and gamma quanta of the spontaneous decay of Cf was carried out. It was required to conduct a digital analysis of the responses of neutrons and gamma quanta with a changed distance of the Cf neutron source of a higher neutron yield with the EJ-309 scintillator.

Ключевые слова: non-destructive analysis; analog-digital converter; nuclear fissionable materials; photomultiplier tubes; nanosecond.

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M.Mamadvafoev , D.A.Davlatshoev
Titanium in the rocks of the intrusive complexes of the Kafandara skarn-magnetic ore field (Eastern Gissar)
The article presents data on the probability distribution function of titanium contents, its abundance, Ti / Fe and Ti / Si ratios, correlations (and regression dependences) of titanium with petrogenic elements of rocks of intrusive complexes of the Kafandara ore field.

Ключевые слова: titanium; distribution function; abundance; Ti / Fe and Ti / Si ratios; correlations; regression relationships; rocks; intrusive complexes.

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Use of the drilling results of exploration wells of the Siyohkuhi Janubi area to study bottom sediments
The results of deep prospecting drilling in the Siyohkuhi Janubi area located withtn the Obigarm anticlinal zone are presented in the paper, as well recommendations on the opening of pre-salt deposits while drilling deep wells are given..

Ключевые слова: drilling solution; khemogenic rocks; South Karatau; drilling; anticlinal Valanjin; kellovey+oxsford.

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R.O.Azizov , Sh.Zh.Mirboboev , Z.A.Razykov
Determination of groundwater pollution during the development of gas and gas condensate deposits in the Afgano-Tajik basin
This paper presents a universal regression model for predicting groundwater pollution during the development of gas and gas condensate fields in the Afghan-Tajik basin. The procedure is divided into three parts: forecasting the level of the gas-water contact and its thickness in the water layers. On the second, the volume of associated formation waters with oil and gas was determined, and on the last section, the geochemical composition of the associated formation waters was determined.

Ключевые слова: groundwater; chemical composition; forecasting; gas-water contact; universal regression model; geochemistry; watering of gas wells.

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Sh.A.Faizulloev , D.B.Baygenov , B.A.Alamov , Sh.A.Olimov , Sh.A.Oyqubov
Landslide suscebtibility modeling using ahp method and gis, a case study of the HPP cascade area on the Vakhsh river
The article is devoted to landslide susceptibility modeling of area of the cascade of hydroelectric power stations on the Vakhsh River using AHP method based on the main causative factors which effect for their occurence. The elements of each factor were weighed separately and then the factors causing the landslides themselves were weighed using paired comparisons of the hierarchy analysis method. The results of the assessment were analyzed using the spatial analysis tools of the GIS program ArcGIS Desktop. The most part of factors has been made and analyzed using remote sensing dates. The result of landslide susceptibility assessment is shoved as map where the places with probability occurrence of landslide is showed up.

Ключевые слова: susceptibility; probability of landslide occurrence; digital elevation model; GIS; slope and AHP.

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A.K.Kayumov , S.F.Abdullaev , D.A.Kayumova
Content of heavy metals in the bottom sediments of Varzob river
The results of a study on determining the content of heavy metals (HM) in the form of free elements or oxides in the composition of bottom sediments from the place of formation to the mouth of the Varzob River are presented. Examination of the elemental composition of the samples by X-ray fluorescence analysis showed distribution of copper and chromium at almost the same level for all samples analyzed throughout the Varzob River. The chromium content in all samples corresponds to the MPC level. The lead indicators in Gulbuta exceed the MPC, and the arsenic content in all samples significantly exceeds the MPC. Arsenic levels are particularly high in the upper reaches of the Warzob River to Dagana and in the lower reaches of the river. A comparative analysis of the results obtained with the data on the content of HM in soils in other regions of Tajikistan, as well as an analysis on the content of dust aerosol are carried out.

Ключевые слова: heavy metals; bottom sediment; soil; elemental composition; pollution; maximum permissible concentration; aerosol.

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The degradation of glaciers in the southern slope of the Rushan range by satellite images and the USSR glaciers catalog
The mainresults of monitoring of the degradation of glaciers in the southern slope of the Rushan Range are outlined and compared with the data from the Catalog of Glaciers of the USSR. The satellite images from the Landsat-2, 7 and Sentinel-2A were used for the research. According to the obtained results, the area of glaciation in the period from 1977 to 2019 decreased by 7.214 km or 9.7%.

Ключевые слова: glacier degradation; remote sensing; GIS; climate changing; Gunt river; glaciation of Pamir; Tajikistan.

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M.A.Saliev , F.Mirzokobilova , M.Z.Yusupova , H.M.Akhmedov
The use of digital control technology to assess the impact of climatic factors on the operation of a solar photoelectric plant
The paper provides an assessment of the influence of climatic factors - the transparency of the atmosphere and cloudiness of the area on the generation of electricity from solar photovoltaic installations (SPEU) using digital information control technologies, based on continuous monitoring of voltage and current at the output of a photovoltaic module (PEM) using a microcomputer information system (IS), which provides complete digitalization of the process of measuring, recording, storing experimental data. The use of computer programs for digital analysis and graphic visualization for processing the database makes it possible to study the dynamics of solar energy conversion processes in real time under conditions of a stochastic mode of solar radiation.

Ключевые слова: solar photovoltaic installation; photovoltaic module; atmospheric transparency; cloudiness coefficient; information system; digital control technology.

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O.Kh.Amirzoda , S.K.Davlatshoev , N.B.Kurbonov , F.Kh.Nasrulloev
Conceptual model of optimal management for ensuring water and energy security in the context of climate change
The article discusses the characteristics of the glacial zone and the zone of formation of river flow in Tajikistan due to climate change. A special role in the context of climate change is assigned to the development of a conceptual model of optimal management to ensure water and energy security of the Republic of Tajikistan at the organizational level, technical and economic levels. The aim of creating a conceptual model is to manage large reservoirs with multi-year regulation for power generation and river flow, create conditions for the accumulation of water during high water periods and increase the water content of rivers during low water periods.

Ключевые слова: atmospheric precipitation; river runoff; melting of glaciers; climatic conditions; reservoirs; hydropower resources; long-term regulation; management; conceptual model; optimization.