Pub Date : 1990-01-01DOI: 10.1016/0041-5553(90)90072-Z
A.I. Kalinin
Terminal control of a singularly perturbed linear system, with constraints on the right endpoint of the trajectory is considered. The asymptotic behaviour of the solution is analysed and on that basis an algorithm is proposed for the asymptotic allocation of optimal control switching points. A computational procedure is outlined which utilizes the asymptotic approximations to obtain an exact solution for any given value of the small parameter.
{"title":"A method for the asymptotic solution of singularly perturbed linear terminal control problems","authors":"A.I. Kalinin","doi":"10.1016/0041-5553(90)90072-Z","DOIUrl":"10.1016/0041-5553(90)90072-Z","url":null,"abstract":"<div><p>Terminal control of a singularly perturbed linear system, with constraints on the right endpoint of the trajectory is considered. The asymptotic behaviour of the solution is analysed and on that basis an algorithm is proposed for the asymptotic allocation of optimal control switching points. A computational procedure is outlined which utilizes the asymptotic approximations to obtain an exact solution for any given value of the small parameter.</p></div>","PeriodicalId":101271,"journal":{"name":"USSR Computational Mathematics and Mathematical Physics","volume":"30 2","pages":"Pages 19-28"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0041-5553(90)90072-Z","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78132247","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}
Pub Date : 1990-01-01DOI: 10.1016/0041-5553(90)90184-T
M.A. Kokorev
The problem of approximating a function satisfying a Lipschitz condition in the interval [a, b] is considered. A single-step optimal stochastic algorithm for selecting the data points is constructed.
{"title":"Construction of a single-step optimal stochastic algorithm for approximating a Lipschitz function","authors":"M.A. Kokorev","doi":"10.1016/0041-5553(90)90184-T","DOIUrl":"10.1016/0041-5553(90)90184-T","url":null,"abstract":"<div><p>The problem of approximating a function satisfying a Lipschitz condition in the interval [<em>a</em>, <em>b</em>] is considered. A single-step optimal stochastic algorithm for selecting the data points is constructed.</p></div>","PeriodicalId":101271,"journal":{"name":"USSR Computational Mathematics and Mathematical Physics","volume":"30 3","pages":"Pages 8-15"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0041-5553(90)90184-T","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75506825","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}
Pub Date : 1990-01-01DOI: 10.1016/0041-5553(90)90196-Y
M.V. Fedoryuk
The second term in the asymptotic expansion of the contribution from a nondegenerate stationary point is determined for the multidimensional case.
对于多维情况,确定了非退化平稳点贡献的渐近展开式的第二项。
{"title":"The multidimensional stationary phase method. The second term of the asymptotic expansions","authors":"M.V. Fedoryuk","doi":"10.1016/0041-5553(90)90196-Y","DOIUrl":"10.1016/0041-5553(90)90196-Y","url":null,"abstract":"<div><p>The second term in the asymptotic expansion of the contribution from a nondegenerate stationary point is determined for the multidimensional case.</p></div>","PeriodicalId":101271,"journal":{"name":"USSR Computational Mathematics and Mathematical Physics","volume":"30 3","pages":"Pages 104-107"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0041-5553(90)90196-Y","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83164517","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}
Pub Date : 1990-01-01DOI: 10.1016/0041-5553(90)90191-T
G.A. Virnovskii, E.I. Levitan
The problem of determining the field of permeability of an oil-bearing layer from the variations of the pressure and the yield of liquid at the boring wells can be stated as a problem for the minimum value of a functional and can be approximately solved by means of the methods of optimal control theory. The construction of numerical schemes is discussed. The results of a numerical solution of the problem enable one to draw conclusions regarding the uniqueness of the solution.
{"title":"Identification of a two-dimensional model of the flow of a homogeneous liquid in a porous medium","authors":"G.A. Virnovskii, E.I. Levitan","doi":"10.1016/0041-5553(90)90191-T","DOIUrl":"10.1016/0041-5553(90)90191-T","url":null,"abstract":"<div><p>The problem of determining the field of permeability of an oil-bearing layer from the variations of the pressure and the yield of liquid at the boring wells can be stated as a problem for the minimum value of a functional and can be approximately solved by means of the methods of optimal control theory. The construction of numerical schemes is discussed. The results of a numerical solution of the problem enable one to draw conclusions regarding the uniqueness of the solution.</p></div>","PeriodicalId":101271,"journal":{"name":"USSR Computational Mathematics and Mathematical Physics","volume":"30 3","pages":"Pages 64-70"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0041-5553(90)90191-T","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82563314","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}
Pub Date : 1990-01-01DOI: 10.1016/0041-5553(90)90095-A
V.N. Grebenev
A one-dimensional model problem concerning the diffusion of a domain of turbulent perturbations in a homogeneous fluid is considered. It is assumed that the process takes place in a half-strip and is characterized by the equation of balance for the turbulent energy. A theorem on the existence of a solution is proved.
{"title":"On the solvability of the problem of the development of a domain of turbulent homogeneous fluid","authors":"V.N. Grebenev","doi":"10.1016/0041-5553(90)90095-A","DOIUrl":"10.1016/0041-5553(90)90095-A","url":null,"abstract":"<div><p>A one-dimensional model problem concerning the diffusion of a domain of turbulent perturbations in a homogeneous fluid is considered. It is assumed that the process takes place in a half-strip and is characterized by the equation of balance for the turbulent energy. A theorem on the existence of a solution is proved.</p></div>","PeriodicalId":101271,"journal":{"name":"USSR Computational Mathematics and Mathematical Physics","volume":"30 2","pages":"Pages 187-190"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0041-5553(90)90095-A","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82623622","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}
Pub Date : 1990-01-01DOI: 10.1016/0041-5553(90)90156-M
E.K. Kostousova
{"title":"Approximating the measurement optimization problems for a parabolic system","authors":"E.K. Kostousova","doi":"10.1016/0041-5553(90)90156-M","DOIUrl":"10.1016/0041-5553(90)90156-M","url":null,"abstract":"","PeriodicalId":101271,"journal":{"name":"USSR Computational Mathematics and Mathematical Physics","volume":"30 5","pages":"Pages 8-17"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0041-5553(90)90156-M","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"90062420","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}
Pub Date : 1990-01-01DOI: 10.1016/0041-5553(90)90177-T
I.A. Vasin, A.I. Prilepko
{"title":"The solvability of the three-dimensional inverse problem for the non-linear Navier-Stokes equations","authors":"I.A. Vasin, A.I. Prilepko","doi":"10.1016/0041-5553(90)90177-T","DOIUrl":"10.1016/0041-5553(90)90177-T","url":null,"abstract":"","PeriodicalId":101271,"journal":{"name":"USSR Computational Mathematics and Mathematical Physics","volume":"30 5","pages":"Pages 189-199"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0041-5553(90)90177-T","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86089803","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}
Pub Date : 1990-01-01DOI: 10.1016/0041-5553(90)90076-5
A.A. Kobozeva, L.V. Maslovskaya
An approach to the programming of a new algorithm involving a certain numbering of the unknowns is proposed, the use of which does not require permutation of rows and columns of the system to ensure stability of the solution algorithm. A method is proposed for solving the corresponding system of linear algebraic equations, whose matrix is not positive-definite but is of a special form.
{"title":"Programming a generalized cholesky algorithm for mixed discrete analogues of elliptic boundary-value problems","authors":"A.A. Kobozeva, L.V. Maslovskaya","doi":"10.1016/0041-5553(90)90076-5","DOIUrl":"10.1016/0041-5553(90)90076-5","url":null,"abstract":"<div><p>An approach to the programming of a new algorithm involving a certain numbering of the unknowns is proposed, the use of which does not require permutation of rows and columns of the system to ensure stability of the solution algorithm. A method is proposed for solving the corresponding system of linear algebraic equations, whose matrix is not positive-definite but is of a special form.</p></div>","PeriodicalId":101271,"journal":{"name":"USSR Computational Mathematics and Mathematical Physics","volume":"30 2","pages":"Pages 56-62"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0041-5553(90)90076-5","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89515448","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}
Pub Date : 1990-01-01DOI: 10.1016/0041-5553(90)90061-V
M.N. Zakharenkov
In the context of the numerical treatment of the two-dimensional Navier-Stokes equations, the boundary conditionsatasolid surface may be realized in different ways, some of which are examined. The approach considered here assumes that the equations of the system are solved separately. It is shown that then, irrespective of the specific formulation of the Navier-Stokes equations for an incompressible viscous liquid — in terms of velocity-pressure, velocity-vorticity or vorticity-stream function — the boundary conditions can be realized in an algorithmically universal way, based on a two-parameter formula previously proposed to approximate vorticity on a wall.
{"title":"Special features of difference schemes for solving the two-dimensional Navier-Stokes equations, connected with the formulation of the boundary conditions on the solid surface","authors":"M.N. Zakharenkov","doi":"10.1016/0041-5553(90)90061-V","DOIUrl":"10.1016/0041-5553(90)90061-V","url":null,"abstract":"<div><p>In the context of the numerical treatment of the two-dimensional Navier-Stokes equations, the boundary conditionsatasolid surface may be realized in different ways, some of which are examined. The approach considered here assumes that the equations of the system are solved separately. It is shown that then, irrespective of the specific formulation of the Navier-Stokes equations for an incompressible viscous liquid — in terms of velocity-pressure, velocity-vorticity or vorticity-stream function — the boundary conditions can be realized in an algorithmically universal way, based on a two-parameter formula previously proposed to approximate vorticity on a wall.</p></div>","PeriodicalId":101271,"journal":{"name":"USSR Computational Mathematics and Mathematical Physics","volume":"30 4","pages":"Pages 182-190"},"PeriodicalIF":0.0,"publicationDate":"1990-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/0041-5553(90)90061-V","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80386970","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}