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Extrapolation of Tomographic Images Based on Dataof Multiple Pulsed Probing
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030189
I. P. Yarovenko, P. A. Vornovskikh, I. V. Prokhorov
{"title":"Extrapolation of Tomographic Images Based on Data\u0000of Multiple Pulsed Probing","authors":"I. P. Yarovenko,&nbsp;P. A. Vornovskikh,&nbsp;I. V. Prokhorov","doi":"10.1134/S1990478924030189","DOIUrl":"10.1134/S1990478924030189","url":null,"abstract":"<p> This paper proposes a new approach to improving image quality in pulsed X-ray\u0000tomography. The method is based on establishing a functional dependence of the reconstructed\u0000images on the duration of the probing pulses and applying an extrapolation procedure. The\u0000numerical experiments demonstrated that the developed algorithm effectively suppresses the\u0000influence of scattered radiation and significantly increases image contrast. The proposed\u0000alternative approach allows substantially increasing the stability of the method even for media\u0000containing strong scattering inhomogeneities and with a significant level of noise in the projection\u0000data. In addition, the algorithm has greater stability to errors in the source data caused by an\u0000increase in the duration of the probing pulses. The numerical experiments confirmed the high\u0000efficiency of the extrapolation tomography algorithm for recovering the internal structure of the\u0000test object.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"583 - 597"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757895","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
Solvability of an Initial–Boundary Value Problemfor a Parabolic Equation with a Time-Nonlocal Termin Hölder spaces
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030062
A. S. Fomenko
{"title":"Solvability of an Initial–Boundary Value Problem\u0000for a Parabolic Equation with a Time-Nonlocal Term\u0000in Hölder spaces","authors":"A. S. Fomenko","doi":"10.1134/S1990478924030062","DOIUrl":"10.1134/S1990478924030062","url":null,"abstract":"<p> We consider an initial–boundary value problem for a semilinear parabolic differential\u0000equation with a time-nonlocal term. This term contains the integral of the solution over the entire\u0000time interval on which the problem is considered. The solvability of the problem in\u0000Hölder classes is proved. The uniqueness of the solution is established under a constraint\u0000on the length of the time interval over which the solution is integrated in the nonlocal term.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"441 - 447"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757896","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
On the Maximum Number of Open Triangles in Graphs withFew Edges
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030128
A. V. Pyatkin
{"title":"On the Maximum Number of Open Triangles in Graphs with\u0000Few Edges","authors":"A. V. Pyatkin","doi":"10.1134/S1990478924030128","DOIUrl":"10.1134/S1990478924030128","url":null,"abstract":"<p> A three-vertex subset is called an open triangle (OT) if it induces a subgraph with exactly\u0000two edges. The problem of finding graphs with maximum number of OTs is considered. It is\u0000proved that, in case of sufficiently many vertices, such a graph is unique in the class of graphs\u0000with constant difference between the numbers of edges and vertices.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"516 - 520"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757915","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
The Problem of One Machine with Equal Processing Time andPreemption
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030098
K. A. Lyashkova, V. V. Servakh
{"title":"The Problem of One Machine with Equal Processing Time and\u0000Preemption","authors":"K. A. Lyashkova,&nbsp;V. V. Servakh","doi":"10.1134/S1990478924030098","DOIUrl":"10.1134/S1990478924030098","url":null,"abstract":"<p> We consider the problem of minimizing the weighted average execution time of\u0000equal-length jobs performance on one machine at the specified time of job arrival and the\u0000possibility of their interruption. The computational complexity of this problem is currently\u0000unknown. The article proposes an algorithm for preprocessing input data that allows reducing the\u0000problem to a narrower and more regular class of examples. The properties of optimal solutions are\u0000substantiated. Based on them, an algorithm for constructing a finite subset of solutions containing\u0000an optimal schedule has been developed. A parametric analysis of the schedules in this subset has\u0000been carried out that makes it possible to form a subclass of schedules that are optimal at some\u0000values of weights. A polynomially solvable case of the problem is isolated.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"479 - 488"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757937","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
Convex Continuations of Some DiscreteFunctions
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030049
D. N. Barotov
{"title":"Convex Continuations of Some Discrete\u0000Functions","authors":"D. N. Barotov","doi":"10.1134/S1990478924030049","DOIUrl":"10.1134/S1990478924030049","url":null,"abstract":"<p> We construct convex continuations of discrete functions defined on the vertices of the\u0000<span>( n )</span>-dimensional unit cube\u0000<span>( [0,1]^n )</span>, an arbitrary cube\u0000<span>( [a,b]^n )</span>, and a parallelepiped\u0000<span>( [c_1,d_1]times [c_2,d_2]times dots times [c_n,d_n] )</span>. In each of these cases, we constructively prove that, for any discrete function\u0000<span>( f )</span> defined on the vertices of\u0000<span>( mathbb {G} in {[0,1]^n, [a,b]^n, [c_1,d_1]times [c_2,d_2]times dots times [c_n,d_n]} )</span>, first, there exist infinitely many convex continuations to the set\u0000<span>( mathbb {G} )</span>, and second, there exists a unique function\u0000<span>( f_{DM}colon mathbb {G}to mathbb {R} )</span> that is the maximum of convex continuations of\u0000<span>( f )</span> to\u0000<span>( mathbb {G} )</span>. We also show that the function\u0000<span>( f_{DM} )</span> is continuous on\u0000<span>( mathbb {G} )</span>.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"412 - 423"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757894","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
On Conditions for the Well-Posed Solvabilityof a Factorization Problem and a Classof Truncated Wiener–Hopf Equations
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030177
A. F. Voronin
{"title":"On Conditions for the Well-Posed Solvability\u0000of a Factorization Problem and a Class\u0000of Truncated Wiener–Hopf Equations","authors":"A. F. Voronin","doi":"10.1134/S1990478924030177","DOIUrl":"10.1134/S1990478924030177","url":null,"abstract":"<p> This paper continues the study of the relationship between the convolution equation of the\u0000second kind on a finite interval\u0000<span>( (0, tau ) )</span> (which is also called the truncated Wiener–Hopf equation) and\u0000a factorization problem (which is also called a vector Riemann–Hilbert boundary value problem or\u0000a vector Riemann boundary value problem). The factorization problem is associated with a family\u0000of truncated Wiener–Hopf equations depending on the parameter\u0000<span>( tau in (0,infty ) )</span>. The well-posed solvability of this family of equations is shown depending on\u0000the existence of a canonical factorization of some matrix function. In addition, various possible\u0000applications of the factorization problem and truncated Wiener–Hopf equations are considered.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"575 - 582"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757914","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
Calculation of Thermal Currents in a Tungsten Plate and in aThin Layer of Tungsten Vapor during Pulse Heating with Allowance for Temperature- andPhase-Dependent Electrical Resistance and Thermo EMF
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030086
G. G. Lazareva, V. A. Popov
{"title":"Calculation of Thermal Currents in a Tungsten Plate and in a\u0000Thin Layer of Tungsten Vapor during Pulse Heating with Allowance for Temperature- and\u0000Phase-Dependent Electrical Resistance and Thermo EMF","authors":"G. G. Lazareva,&nbsp;V. A. Popov","doi":"10.1134/S1990478924030086","DOIUrl":"10.1134/S1990478924030086","url":null,"abstract":"<p> In this paper, we consider a model of current distribution in a tungsten specimen and the\u0000evaporated substance when the surface is heated by an electron beam. The model is based on\u0000solving the equations of electrodynamics and the two-phase Stefan problem for calculating the\u0000specimen area temperature in a cylindrical coordinate system. We use a model temperature\u0000distribution in a thin layer of evaporated tungsten that replicates the surface temperature.\u0000Thermal currents are obtained using approximate temperature dependences of the electrical\u0000resistance and thermo emf of tungsten and its vapor. The model parameters are taken from\u0000experiments at the Beam of Electrons for materials Test Applications (BETA) stand, created at\u0000the Budker Institute of Nuclear Physics of the Siberian Branch of the Russian Academy of\u0000Sciences.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"465 - 478"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757920","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
A Computational Study of Cuttings Transportin a Horizontal Well with an Oil-Based Drilling Fluid Modified by Multiwalled CarbonNanotubes
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030190
V. A. Zhigarev, D. V. Guzei, E. I. Lysakova, V. Ya. Rudyak, A. V. Minakov
{"title":"A Computational Study of Cuttings Transport\u0000in a Horizontal Well with an Oil-Based Drilling Fluid Modified by Multiwalled Carbon\u0000Nanotubes","authors":"V. A. Zhigarev,&nbsp;D. V. Guzei,&nbsp;E. I. Lysakova,&nbsp;V. Ya. Rudyak,&nbsp;A. V. Minakov","doi":"10.1134/S1990478924030190","DOIUrl":"10.1134/S1990478924030190","url":null,"abstract":"<p> We have conducted a computational study of the effect of adding multiwalled carbon\u0000nanotubes (MWCNTs) to oil-based drilling fluids on the efficiency of cuttings removal from\u0000an annular channel simulating a horizontal section of a well. To simulate the process of sludge\u0000transport in an annular channel, a mathematical model based on the Eulerian approach of\u0000a granular medium for a turbulent flow regime has been developed. The rheology of the drilling\u0000fluid modified with MWCNTs was described by the Herschel–Bulkley model with experimentally\u0000determined rheological coefficients. The base oil-based drilling fluid was an inverse emulsion with\u0000a ratio of hydrocarbon and water phases equal to 65/35. The concentration of MWCNTs in\u0000solutions varied from 0.1 to 0.5 wt %. The size of the transported sludge particles varied\u0000from 2 to 7 mm. The flow structure of a two-phase flow in an annular channel for various\u0000concentrations of MWCNTs has been studied. The dependences of the sludge removal efficiency\u0000coefficient, the average slip speed of sludge particles, and pressure losses on the concentration of\u0000nanotubes are obtained. It has been established that the addition of nanotubes leads to a\u0000significant change in the flow pattern of the drilling fluid and, as a result, to a change in the\u0000modes of cuttings transport. Addition of 0.5 wt % of MWCNTs leads to an increase in the\u0000efficiency of well flushing by approximately 40%. Thus, based on the results of the computational\u0000study, it has been shown that the addition of multiwalled nanotubes to oil-based drilling fluids can\u0000lead to an increase in the efficiency of cuttings transport in horizontal wells.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"598 - 611"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757921","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
A Cubic Version of the Least-Squares Collocation Method andIts Application to the Calculationof Plate Bending
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030074
S. K. Golushko, L. S. Bryndin, V. A. Belyaev, A. G. Gorynin
{"title":"A Cubic Version of the Least-Squares Collocation Method and\u0000Its Application to the Calculation\u0000of Plate Bending","authors":"S. K. Golushko,&nbsp;L. S. Bryndin,&nbsp;V. A. Belyaev,&nbsp;A. G. Gorynin","doi":"10.1134/S1990478924030074","DOIUrl":"10.1134/S1990478924030074","url":null,"abstract":"<p> A new cubic version of the least-squares collocation method based on adaptive grids is\u0000developed. Approximate values of the solution and its first derivatives at the vertices of\u0000quadrangular cells are the unknowns. This approach has made it possible to eliminate the\u0000matching conditions from the global overdetermined system of linear algebraic equations\u0000consisting of collocation equations and boundary conditions. The preconditioned system is solved\u0000using the <span>SuiteSparse</span> library by the\u0000orthogonal method with the CUDA parallel programming technology. We consider the\u0000Reissner–Mindlin plate problem in a mixed formulation. A higher accuracy of deflections and\u0000rotations of the transverse normal in comparison with the isogeometric collocation method as well\u0000as the uniform convergence of shear forces in the case of a thin plate are shown in the proposed\u0000method. Bending of an annular plate and round plates with an off-center hole is analyzed. An\u0000increase in the shear force gradient in the vicinity of the hole is shown both with a decrease in the\u0000plate thickness and with an increase in the eccentricity. The second order of convergence of the\u0000developed method is shown numerically. The results obtained using the Reissner–Mindlin theory\u0000are compared with the ones in the Kirchhoff–Love theory and three-dimensional finite element\u0000simulation.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"448 - 464"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757922","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
Search for Locally Optimal Strategies in a Linear Game Problemwith Favorable Situations
IF 0.58
Journal of Applied and Industrial Mathematics Pub Date : 2024-12-01 DOI: 10.1134/S1990478924030104
A. R. Mamatov
{"title":"Search for Locally Optimal Strategies in a Linear Game Problem\u0000with Favorable Situations","authors":"A. R. Mamatov","doi":"10.1134/S1990478924030104","DOIUrl":"10.1134/S1990478924030104","url":null,"abstract":"<p> A linear game problem for two players is considered. The two players alternately choose\u0000their strategies from their respective sets. First, player 1 chooses his/her strategy, then player 2,\u0000knowing the strategy of player 1, does the same. The set of strategies of player 2 depends on the\u0000strategy of player 1. The goal of player 1 is to choose a strategy to maximize a convex and\u0000piecewise linear function (the minimum function of the strategy of player 2). The goal of player 2\u0000is to minimize the linear function. An algorithm is proposed that allows constructing strategies in\u0000this problem, as well as strategies in the dual problem, that satisfy necessary “higher-order”\u0000optimality conditions. This algorithm uses a formula for the increment of the objective function in\u0000the dual problem. Theorems that assert the finiteness of the proposed algorithm and its\u0000modification are proved. An example illustrating the operation of the algorithm is given. The\u0000results of a numerical experiment on the construction of strategies that satisfy the necessary\u0000“higher-order” optimality conditions in problems whose elements were generated by a random\u0000number generator are also presented. Based on the results of the numerical experiment, we can\u0000conclude that with the proposed algorithm, it is often possible to switch from one locally optimal\u0000strategy of player 1 to another one increasing the objective function.\u0000</p>","PeriodicalId":607,"journal":{"name":"Journal of Applied and Industrial Mathematics","volume":"18 3","pages":"489 - 502"},"PeriodicalIF":0.58,"publicationDate":"2024-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142757924","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
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