Доклады Академии наук Республики Таджикистан, том 63, №03-04, 2020 г.
|Article title and abstract||Pages|
Some exact inequalities between the best approximations and non-classical modulus of continuity in L
We obtain an estimate for the best mean-square approximation of an arbitrary complex-valued
2-periodic function by the subspace of trigonometric polynomials of degree at most -1 in terms of the nonclassical modulus of continuity
Key words: best approximation; nonclassical modulus of continuity; Jackson-Stechkin inequality.
|Shabozov M.Sh., Abdulkhaminov M.A.|
Some inequalities between the best polinomial approximations and the averaged norms of finite differences in space L and the diameters of functional classes
Exact constants in Jackson-Stechkin type inequalities for smoothness characteristics , are determined by averaging the norm in finite differences of m-th order of function . For classes of functions defined by the smoothness characteristic and majoranrs satisfying a certain condition, the exact values of various -th diameters are calculated.
Key words: approximations; finite differences of m-th order; smoothness characteristic; n-diameters.
Generalized double-periodic solutions of one elliptic systems of second-order equations
In this work for one class of second-order elliptic systems on the plane, we found generalized double-periodic solutions with given poles using the Weierstrass elliptic functions. In this case, the methods of double-periodic generalized analytic functions are used.
Key words: regular solutions; double-periodic function; double-periodic solution; Weierstrass functions; analytic functions.
On the existence of a bounded solution of systems
of nonlinear differential equations on the plane
In this paper the existence of a bounded solution for one class of systems of nonlinear differential equations are investigated. Using the method of periodic slices, it is proved that if the coefficients of the system of equations satisfy certain conditions, then there is a bounded solution that is separated from zero.
Key words: system of nonlinear differential equations; periodic solution; topological method; rotation of the vector field; method of periodic cuts.
Evaluation of the efficiency of using γ-classifier for attribution of printed text
The essence of the new method, called the γ-classifier, is described in detail, the related concepts are interpreted, a new digital portrait is proposed for the formation of a quantitative model of the text based on the distribution of the frequency of anagram codes.
Key words: text; digital portrait; γ-classifier.
|Kosimov A.A., Bachteev R.S.|
About recognition of the authors text based on the frequency of length of sentences
In this article the problem of recognizing the authors of works separately for classical and modern poetry, as well as modern prose, is solved. Each work is associated with a digital portrait - the distribution of the frequency of the lengths of sentences. The effectiveness of applying the γ-classifier for identifying authors of text is established.
Key words: Tajik language; text; poetry; prose; frequency; classifier; identification.
|Kokhirova G.I., Babadzhanov P.B., Khamroev U.H., Zhonmuhammadi A.I., Kulaev I.V.|
Virginid asteroid-meteoroid complex.
Near-Earth asteroids associated with the Alpha-Virginid meteoroid stream
The Virginid meteoroid stream produces a series of meteor showers and sub-showers active annually during February-May. A certain parent comet is not found but a related association of some showers with near-Earth asteroids was previously established and a cometary origin of these asteroids was suggested. We performed a new search for NEAs belonging to the Virginid asteroid-meteoroid complex. On the base of calculation of orbital evolution of a sample of NEAs and determination of theoretical features of related showers a search for observable active showers close to theoretically predicted ones was carried out. As a result, predicted showers of 15 NEAs were identified with the showers produced by the a-Virginid meteoroid stream. Revealed association points to a cometary nature of NEAs that are moving within the stream and may be considered as extinct fragments of a larger comet-progenitor of the Virginid asteroid-meteoroid complex.
Key words: comet; asteroid; extinct comet; meteoroid stream; meteor shower; orbit; radiant.
|Sharipov S.R., Abdullaev S.F., Maslov V.A., Madvaliev U.|
Variability in the composition of the carbon-containing fraction of atmospheric aerosol in the semi-arid zone
In this article the results of a two-year (2014-2016) experiment to measure the content in organic and elementary carbon aerosols conducted at the Atmospheric Monitoring Station (Dushanbe, 38º 33´34´´N, 68º51´22´´E) are presented. The article describes the possible sources of atmospheric carbon, the results of the application of the method of polynomial regression to data on carbon content. The back trajectories of air masses are given with the maximum content of elemental and organic carbon.
Key words: atmospheric composition; carbon-containing aerosol; two-stage thermographic method; polynomial regression.
|Salikhov T.Kh., Melikkhudzha N., Mahmalatif A., Khojaev Yu.P.|
Contribution of substrate absorption to the formation
of the second harmonic of nonlinear photoacoustic response of the two layer samples
A theory of the generation of the second harmonic (SG) of a nonlinear photoacoustic response the two layers sample has been proposed for the cases when the substrate, along with the board layers of sample, is absorbing. The necessary expression for the complex amplitude of temperature perturbations in the buffer gas is obtained. The case when the board layers of sample are thermally thin and transparent is investigated in detail. For this case, expressions are obtained that describe the features of the dependence the amplitude of the SG of nonlinear PA-signal at the modulation frequency and optical absorption coefficient.
Key words: photoacoustic; two layer samples; thermal nonlinearity; second harmonic.
|Tuichiev Sh., Rashidov D., Tuichiev Kh., Dustov A.I., Tuichiev L.|
Microdeformational properties of nanocarbon-containing oriented polymeric nanocomposites
Temperature and deformation tests were used to study the microdeformation properties of oriented fullerene-containing samples from LDPE. It is assumed that the embedded nanoparticles are localized in the intrafibrillar amorphous regions, favor the enhancement of the intrafibrillar bond and change the microformational properties of the nanocomposites.
Key words: polymer; fullerene; nanocomposite; structure; microdeformational properties.
|Otaev Sh.D., Mirzoev D.Kh., Jamolov M.N., Mirsaidov U.M.|
Physical and chemical bases of kaolin clay processing of the Tajikistan Chashma-Sang deposit by sintering with sodium hydroxide followed nitrogen acid decomposition
In this article the physicochemical bases of the decomposition of kaolin clays of the Tajikistan Chashma-Sang deposit by sintering with sodium hydroxide followed by nitric acid decomposition of sinter have been studied. The optimal parameters of sinter decomposition after water and acid treatment as well as have been found. A principal technological flow chart has been developed for the processing of Chashma-Sang kaolin clay by sintering with NaOH and subsequent aqueous and acid treatment of sinter.
Key words: sintering; sodium hydroxide; kaolin clay; nitric acid; decomposition; technological flow chart.
|Abdusalyamova M.N., Badalova M.A., Makhmudov F.A., Kabgov Kh.B.|
The physico-chemical characters
of YbMnSb doped by Ln (La-Sm)
The YbMnSband solid solutions YbLnMnSb (Ln=La-Sm; x= 0.1; 0.3; 0.5; 0.7; 0.9) were as single crystals via Sn flux were grown. All phases crystallized in the tetragonal structure type, CaAlSb. The maximum amount of Ln was determined from wavelength dispersive microprobe analysis to be x≈0.45. Data on structure, melting point, thermal dilation in this paper are presented.
Key words: thermoelectric materials; Zintl phase; solid solution; lantanoides.
|Aminjoni G., Naimov N.A., Safiev A.H., Nazarov Sh.B., Ruziev J.R., Safiev H.|
Development of technology for enrichment of muscovit-stavrolite shale of Kurgovad deposit by flotation method
In this work the results of a study of the enrichment of muscovite-staurolite schists of the Kurgovad field by flotation are presents. During the flotation enrichment process, the optimal parameters of the flotation reagents used and the duration of the process were determined, and physicochemical analyzes of the concentrates and flotation tails obtained were carried out.
Key words: muscovite-staurolite schists; alumina; flotation; enrichment; flotation reagents; flotation concentrates; flotation tailings.
|Mamadvafoev M.M., Davlatshoev D.A.|
About the laws for the distribution of the contents of petrogen elements in the rocks of intrusive complexes of the Kafandara ore field (Eastern Hissar)
In this work the laws (functions) of the distribution of the contents of petrogenic elements in inversion (C2-C3) granitoids, their dike varieties and post-inversion-orogenic (P1) subvolcanic dykes of the porphyry formation are determined. It is established that out of 132 empirical distributions of the contents of petrogenic oxides, a hypothetical normal law approximates 78% of them. Only 13% of empirical distributions are consistent with the lognormal law, and 9% of the distributions are not consistent with either the normal law or the lognormal, which raises the question of developing an approximating probabilistic-statistical law of their distribution.
Key words: East Gissar; Kafandar ore field; rocks; intrusive complexes; elements; oxides; distribution laws (functions).
|Valiev Yu.Ya., Mamatov E.D., Khisainov T.Kh., Kabgov H.B., Rahimi F.|
The study of phosphorite ore of the Hissar and Turkestan ranges of Tajikistan
In this work the results of a study of phosphorite ores of deposits in Tajikistan are presents. Compiled their lithological section and shows the material composition of rock-forming and basic minerals.
Key words: phosphorite ore; lithological section; material composition; phosphorus oxide; phosphorus fertilizer.
|Rustamov A.R., Atoev M.H., Jumaev B.B., Abdullaev A., Ergashev A.|
Photosynthetic of carbon metabolism in polyploid forms of soft wheat under conditions of drought
In this article the results of study on the effect of soil drought on the photosynthetic metabolism of carbon in the leaves of different varieties of soft wheat are present. It has been established that in the condition of soil drought significant changes occur in the rate and in the direction of carbon metabolism - С in photosynthesis. It was revealed that the soil drought noticeably changed the character of distribution of C among the products of photosynthesis.
Key words: soft wheat; soil drought; photosynthesis; products of photosynthesis; carbon metabolism.
|Sharipova H.T., Partoev K., Husenov Z., Abdullayev A.|
Influence of sodium chloride on seed germination, seedling growth and of wheat (Triticum aestivum L.) tollerans to yellow rust (Puccinia graminis)
It was found that under the influence of 0.5 and 1.0% concentration of sodium chloride (NaCl) there is an increase in germination of wheat seeds (respectively 19.3 and 17.9%), and 1.5% concentration of NaCl leads to a decrease in seed germination by 7.8% than in the control. Under the influence of 0.5 % concentration of NaCl there is a positive effect on the length of wheat germ compared to the control (4.5%), when 1.0 and 1.5% concentration of NaCl lead to a significant decrease in the length of the germs compared to the control, respectively 29.5 and 68.8%.
Key words: wheat; variety; seeds; sodium chloride; concentration; yellow rust.
|Avezov T.Sh., Ergashev A.|
The effect of antioxidants on the content of photosynthetic pigments and the intensity of photosynthesis in some wheat varieties
Processing of seeds of Triticum aestivum and Triticum durum varieties by steeping in a solution of vitamin C, α-tocopherol and zinc ferrositrate increases the content of photosynthetic pigment of 5-7 day seedlings. The same regularity was observed in seedlings growing under the soil drought conditions. The quantitative variability of the pigment content depended on the type of antioxidant, the species of wheat and the pigment type (chl. a, b, and carotenoids).
Key words: wheat; antioxidant; germination; drought; pigment.