Russian Mathematics最新文献_第6页

Equivalence of Computed Tomography Problem with the Problem of Recovery of Functions by Finite Convolutions in a Scheme of Computational (Numerical) Diameter 计算（数值）直径方案中的计算机断层扫描问题与通过有限卷积恢复函数问题的等价性

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Russian Mathematics Pub Date : 2024-02-28 DOI: 10.3103/s1066369x23120095

N. Temirgaliyev, Sh. K. Abikenova, Sh. U. Azhgaliyev, Ye. Ye. Nurmoldin, G. E. Taugynbayeva, A. Zh. Zhubanysheva

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Three-Webs from Circles 来自圆圈的三张网

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Russian Mathematics Pub Date : 2024-02-28 DOI: 10.3103/s1066369x23120083

A. M. Shelekhov

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Compound Cubature Formulas on a Lattice 网格上的复立方公式

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Russian Mathematics Pub Date : 2024-02-19 DOI: 10.3103/s1066369x23110087

Kh. M. Shadimetov, N. Kh. Mamatova

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Finite Element Modeling of Eigenvibrations of a Square Plate with an Attached Oscillator 附带振子的方形板特征振动的有限元建模

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Russian Mathematics Pub Date : 2024-02-19 DOI: 10.3103/s1066369x2311004x

D. M. Korosteleva, S. I. Solov’ev

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The Riemann Problem in a Half-Plane for Generalized Analytic Functions with a Supersingular Point on the Contour of the Boundary Condition 边界条件轮廓上有超星点的广义解析函数的半平面黎曼问题

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Russian Mathematics Pub Date : 2024-02-19 DOI: 10.3103/s1066369x23110075

P. L. Shabalin

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Approximation of the Lebesgue Constant of the Fourier Operator by a Logarithmic-Fractional-Rational Function 用对数-分数-有理函数逼近傅立叶算子的勒贝格常数

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Russian Mathematics Pub Date : 2024-02-19 DOI: 10.3103/s1066369x23110099

I. A. Shakirov

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Method and Algorithm for Calculating Isobaric and Nonisobaric Three-Dimensional Turbulent Jets of Reacting Gases 计算等压和非等压三维反应气体湍流射流的方法和算法

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Russian Mathematics Pub Date : 2024-02-19 DOI: 10.3103/s1066369x23110038

S. Khodzhiev

{"title":"Method and Algorithm for Calculating Isobaric and Nonisobaric Three-Dimensional Turbulent Jets of Reacting Gases","authors":"S. Khodzhiev","doi":"10.3103/s1066369x23110038","DOIUrl":"https://doi.org/10.3103/s1066369x23110038","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3>This paper presents a calculation method and algorithm, as well as numerical results of studying chemically reacting turbulent jets based on three-dimensional parabolic systems of Navier–Stokes equations for multicomponent gas mixtures. Continuity equations are used to calculate the mass imbalance when solving with constant pressure, and with variable pressures, with the equations of motion and continuity. Diffusion combustion of a propane–butane mixture flowing from a square-shaped nozzle in a submerged flow of an air oxidizer is numerically studied. Pressure variability significantly affects the velocity (temperature) profiles in the initial sections of the jet, and, when moving away from the nozzle exit, the pressure effect can be considered imperceptible, but the plume length is longer than that at constant pressure, but it does not significantly affect the shape of the plume. The saddle-shaped behavior of the longitudinal velocity in the direction of the major axis is numerically obtained for large initial values of the turbulence kinetic energy of the main jet. The presented method allows studying nonreacting and reactive turbulent jets flowing from a rectangular nozzle.","PeriodicalId":46110,"journal":{"name":"Russian Mathematics","volume":"300 1","pages":""},"PeriodicalIF":0.4,"publicationDate":"2024-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139902432","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Curves Whose Arcs with a Fixed Startpoint Are Similar 固定起点的弧线相似的曲线

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Russian Mathematics Pub Date : 2024-02-19 DOI: 10.3103/s1066369x23110063

I. V. Polikanova

{"title":"Curves Whose Arcs with a Fixed Startpoint Are Similar","authors":"I. V. Polikanova","doi":"10.3103/s1066369x23110063","DOIUrl":"https://doi.org/10.3103/s1066369x23110063","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3>The author has previously put forward a hypothesis that in n-dimensional Euclidean space, curves, any two oriented arcs of which are similar, are rectilinear. The author also proved this statement for dimensions of n = 2 and n = 3. In a space of arbitrary dimension, this hypothesis was confirmed in the class of rectifiable curves. In this study, the author provides a complete solution to this problem that is even stronger: (a) a curve in E n, where any two oriented arcs starting at an common nonfixed point are similar is rectilinear; (b) if a curve in E n has a half-tangent at its boundary point and any two of its oriented arcs emanating from this point are similar, then the curve is rectilinear; (c) if a curve in E n has a tangent at an inner point and all its oriented arcs starting at this point are similar, then the curve is rectilinear. Examples of curves in E2 and E3 are given, that are not rectilinear, although their arcs having a common startpoint are similar, and a complete description of such curves in E2 is given. Research methods are topological and set-theoretic using the apparatus of functional equations.","PeriodicalId":46110,"journal":{"name":"Russian Mathematics","volume":"62 1","pages":""},"PeriodicalIF":0.4,"publicationDate":"2024-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139902538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Inverse Coefficient Problems for a Time-Fractional Wave Equation with the Generalized Riemann–Liouville Time Derivative 具有广义黎曼-刘维尔时间导数的时分波方程的反系数问题

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Russian Mathematics Pub Date : 2024-01-09 DOI: 10.3103/s1066369x23100092

H. H. Turdiev

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A Block Projection Operator in the Algebra of Measurable Operators 可测算子代数中的一个分块投影算子

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Russian Mathematics Pub Date : 2024-01-09 DOI: 10.3103/s1066369x23100031

A. M. Bikchentaev

{"title":"A Block Projection Operator in the Algebra of Measurable Operators","authors":"A. M. Bikchentaev","doi":"10.3103/s1066369x23100031","DOIUrl":"https://doi.org/10.3103/s1066369x23100031","url":null,"abstract":"<h3 data-test=\"abstract-sub-heading\">Abstract</h3>Let (tau ) be a faithful normal semifinite trace on a von Neumann algebra (mathcal{M}). The block projection operator ({{mathcal{P}}_{n}}) ((n geqslant 2)) in the *-algebra (S(mathcal{M},tau )) of all (tau )-measurable operators is investigated. It has been shown that (A leqslant n{{mathcal{P}}_{n}}(A)) for any operator (A in S{{(mathcal{M},tau )}^{ + }}). If (A in S{{(mathcal{M},tau )}^{ + }}) is invertible in (S(mathcal{M},tau )), then ({{mathcal{P}}_{n}}(A)) is invertible in (S(mathcal{M},tau )). Let (A = Atext{*} in S(mathcal{M},tau )). Then, (i) if ({{mathcal{P}}_{n}}(A) leqslant A) (or if ({{mathcal{P}}_{n}}(A) geqslant A)), then ({{mathcal{P}}_{n}}(A) = A), (ii) ({{mathcal{P}}_{n}}(A) = A) if and only if ({{P}_{k}}A = A{{P}_{k}}) for all (k = 1, ldots ,n); and (iii) if (A,{{mathcal{P}}_{n}}(A) in mathcal{M}) are projections, then ({{mathcal{P}}_{n}}(A) = A). Four corollaries have been obtained. One example presented in paper (A. Bikchentaev and F. Sukochev, “Inequalities for the Block Projection Operators,” J. Funct. Anal. 280 (7), 108851 (2021)) has been refined and strengthened.","PeriodicalId":46110,"journal":{"name":"Russian Mathematics","volume":"20 1","pages":""},"PeriodicalIF":0.4,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139411697","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0