共查询到20条相似文献,搜索用时 46 毫秒
1.
Fully discrete approximation methods for the estimation of parabolic systems and boundary parameters
A spatially and temporally discrete numerical approximation scheme is developed for the identification of a class of semilinear parabolic systems with unknown boundary parameters. The identification problem is formulated as a least squares fit to data subject to an equivalent representation for the dynamics in the form of an abstract evolution equation. Finite-dimensional difference equation state approximations are constructed using a cubic spline-based, Galerkin method and the Padé rational function approximations to the exponential. A sequence of approximating identification problems result, the solutions of which are shown to exist and, in a certain sense, approximate solutions to the original identification problem. Numerical results for two examples, one involving the modeling of biological mixing in deep sea sediment cores, and the other, the estimation of transport parameters for indoor mixing, are discussed. In both examples, the identification is based upon actual experimental data.Parts of the research were carried out while the authors were visitors at the Institute for Computer Applications in Science and Engineering (ICASE), NASA Langley Research Center, Hampton, Virginia, which is operated under NASA Contracts No. NAS1-17070 and No. NAS1-17130.Research supported in part by NSF Grant MCS-8205355, AFOSR Contract 81-0198 and ARO Contract ARO-DAAG-29-K-0029. 相似文献
2.
We develop an abstract framework and convergence theory for Galerkin approximation for inverse problems involving the identification of nonautonomous, in general nonlinear, distributed parameter systems. We provide a set of relatively easily verified conditions which are sufficient to guarantee the existence of optimal solutions and their approximation by a sequence of solutions to a sequence of approximating finite-dimensional identification problems. Our approach is based upon the theory of monotone operators in Banach spaces and is applicable to a reasonably broad class of nonlinear distributed systems. Operator theoretic and variational techniques are used to establish a fundamental convergence result. An example involving evolution systems with dynamics described by nonstationary quasi-linear elliptic operators along with some applications and numerical results are presented and discussed.Part of this research was carried out while the first and third authors were visiting scientists at the Institute for Computer Applications in Science and Engineering (ICASE), NASA Langley Research Center. Hampton, VA, which is operated under NASA Contracts NAS1-17070 and NAS1-18107. Also, a portion of this research was carried out with computational resources made available through a grant to the second and third authors from the San Diego Supercomputer Center operated for the National Science Foundation by General Atomics, San Diego, CA. The research of the first author was supported in part under Grants NSF MCS-8504316, NASA NAG-1-517, AFOSR-84-0398, and AFOSR-F49620-86-C-0111. The second author's research was supported in part by the Fund for the Promotion of Research at the Technion and by the Technion VPR Fund. The research of the third author was supported in part under Grants AFOSR-84-0393 and AFOSR-87-0356. 相似文献
3.
M. R. Malik S. Chuang M. Y. Hussaini 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1982,33(2):189-201
Summary A compact fourth order accurate finite difference scheme is proposed for solving the eigenvalue problem of the temporal and spatial stability of three-dimensional compressible boundary layers. It is applied to the stability study of the flow on a laminar flow control swept wing. The results indicate that the present method provides an accurate and efficient way of calculating the eigenvalues and eigensolutions of the compressible linear stability equations.
Research for this author was supported by NASA Contract No. NAS 1-16572.
Research for this author was supported by NASA Contract No. NCC 1-14.
Research for this author was supported by NASA Contracts No. NAS 1-14472 and NAS 1-15810 while the author was in residence at ICASE, NASA Langley Research Center, Hampton, Va. 23665. 相似文献
Zusammenfassung Ein kompaktes Differenzenschema vierter Ordnung wird vorgeschlagen zur Lösung von Eigenwertproblemen der zeitlichen und räumlichen Stabilität dreidimensionaler zusammendrückbarer Grenzschichten. Es wird zum Stabilitätsstudium der Strömung über einen LFC Flügel angewendet. Die Resultate zeigen, daß es die angewendete Methode erlaubt, genau und effizient die Eigenwerte und Eigenfunktionen der kompressiblen linearen Stabilitätsgleichungen zu berechnen.
Research for this author was supported by NASA Contract No. NAS 1-16572.
Research for this author was supported by NASA Contract No. NCC 1-14.
Research for this author was supported by NASA Contracts No. NAS 1-14472 and NAS 1-15810 while the author was in residence at ICASE, NASA Langley Research Center, Hampton, Va. 23665. 相似文献
4.
To any spatial point-reflection geometry there corresponds a determined commutative kinematic space.Dedicated to Professor Raphael Artzy on his 80th birthday.Research supported by the NATO Scientific Affairs Division grant CRG 900103. 相似文献
5.
6.
W. Kucharz 《manuscripta mathematica》1996,91(1):145-149
Summary A characterization of affine nonsingular complex algebraic curves that are biregularly isomorphic to ℂ is given; it is stated
in terms of approximation of holomorphic maps by regular maps.
The author was partially supported by an NSF grant and NATO Collaborative Research Grants Programme, CRG 930238.
This article was processed by the author using theLatext style file from Springer-Verlag. 相似文献
7.
Testing for parameter changes in ARCH models 总被引:5,自引:0,他引:5
The paper develops the asymptotic theory for CUSUM-type tests for a change point in parameters of an ARCH(∞) model. Special
attention is given to asymptotics under local alternatives.
Research partially supported by EPSRC grant GR/L/78222 from the University of Liverpool.
Partially supported by NATO grant CRG 960503.
Partially supported by the Lithuanian State Science and Studies Foundation, Grant K-014.
Published in Lietuvos Matematikos Rinkinys, Vol. 39, No. 2, pp. 231–247, April–June, 1999. 相似文献
8.
The Kalman-Yakubovich-Popov theorem for stabilizable hyperbolic boundary control systems 总被引:1,自引:0,他引:1
L. Pandolfi 《Integral Equations and Operator Theory》1999,34(4):478-493
In this paper we present a version of the Kalman-Yakubovich-Popov theorem for a class of boundary control systems of hyperbolic type. Unstable, controllable systems are considered and stabilizability withunbounded feedbacks is permitted.Paper partially supported by the Italian MINISTERO DELLA RICERCA SCIENTIFICA E TECNOLOGICA within the program of GNAFA-CNR and by NATO CRG program SA.5-2-05 (CRG940161). 相似文献
9.
Wavelet sparse approximate inverse preconditioners 总被引:1,自引:0,他引:1
We show how to use wavelet compression ideas to improve the performance of approximate inverse preconditioners. Our main idea
is to first transform the inverse of the coefficient matrix into a wavelet basis, before applying standard approximate inverse
techniques. In this process, smoothness in the entries ofA
−1 are converted into small wavelet coefficients, thus allowing a more efficient approximate inverse approximation. We shall
justify theoretically and numerically that our approach is effective for matrices with smooth inverses.
Supported by grants from ONR: ONR-N00014-92-J-1890, and the Army Research Office: DAAL-03-91-C-0047 (Univ. of Tenn. subcontract
ORA4466.04 Amendment 1 and 2). The first and the third author also acknowledge support from RIACS/NASA Ames NAS 2-96027 and
the Alfred P. Sloan Foundation as Doctoral Dissertation Fellows, respectively.
the work was supported by the Natural Sciences and Engineering Research Council of Canada, the Information Technology Research
Centre (which is funded by the Province of Ontario), and RIACS/NASA Ames NAS 2-96027. 相似文献
10.
Geometric stable laws have become an object of attention in recent publications dealing with heavy tailed modeling. Many applications require understanding geometric stable laws on infinite dimensional spaces. This paper studies geometric stable laws on Banach spaces, and their place in the more general family of geometric infinitely divisible laws. Furthermore, we discuss rates of convergence in the domains of attraction of geometric stable laws in Banach spaces.Research was supported by NSF Grant DMS-9103452 and a NATO Scientific Affairs Division Grant CRG 900798. University of California, at Santa Barbara, Santa Barbara, California 93102.Research was supported by ONR Grant N00014-90-J-1287 and United States Israel Binational Science Foundation. School of Operations Research, and Industrial Engineering, Cornell University, Ithaca, New York 14853. 相似文献
11.
We describe Top
op and Sob
op as quasi-varieties by means of suitable schizophrenic objects.Research of the first author supported by grants from the NSERC of Canada and the FCAR du Québec. Research of the second author supported by the Topology grant 40% and by the NATO grant CRG 941330. 相似文献
12.
We study energy solutions of a Cauchy problem for the p-Laplace evolution equation with nonlinear gradient absorption and nonnegative compactly supported initial data. We obtain the sufficient local asymptotic conditions on initial data that imply the backward motion and waiting time phenomena. 相似文献
13.
For large systems of linear equations, iterative methods provide attractive solution techniques. We describe the applicability
and convergence of iterative methods of Krylov subspace type for an important class of symmetric and indefinite matrix problems,
namely augmented (or KKT) systems. Specifically, we consider preconditioned minimum residual methods and discuss indefinite
versus positive definite preconditioning. For a natural choice of starting vector we prove that when the definite and indenfinite
preconditioners are related in the obvious way, MINRES (which is applicable in the case of positive definite preconditioning)
and full GMRES (which is applicable in the case of indefinite preconditioning) give residual vectors with identical Euclidean
norm at each iteration. Moreover, we show that the convergence of both methods is related to a system of normal equations
for which the LSQR algorithm can be employed. As a side result, we give a rare example of a non-trivial normal(1) matrix where
the corresponding inner product is explicitly known: a conjugate gradient method therefore exists and can be employed in this
case.
This work was supported by British Council/German Academic Exchange Service Research Collaboration Project 465 and NATO Collaborative
Research Grant CRG 960782 相似文献
14.
Mario Marchi 《Journal of Geometry》1991,41(1-2):124-132
A fibered incidence loop with parallelism is an incidence group if and only if a generalized Prismenaxiom (cf. Theorem 1, §2) is valid.Dedicated to Walter Benz on the occasion of his 60th birthday.Research partially supported by the Italian Ministry M.U.R.S.T. (40% and 60 %) and by the NATO grant n. CRG 900103. 相似文献
15.
Summary We consider the stationary Navier-Stokes equations, written in terms of the primitive variables, in the case where both the partial differential equations and boundary conditions are inhomogeneous. Under certain conditions on the data, the existence and uniqueness of the solution of a weak formulation of the equations can be guaranteed. A conforming finite element method is presented and optimal estimates for the error of the approximate solution are proved. In addition, the convergence properties of iterative methods for the solution of the discrete nonlinear algebraic systems resulting from the finite element algorithm are given. Numerical examples, using an efficient choice of finite element spaces, are also provided.Supported, in part, by the U.S. Air Force Office of Scientific Research under Grant No. AF-AFOSR-80-0083Supported, in part, by the same agency under Grant No. AF-AFOSR-80-0176-A. Both authors were also partially supported by NASA Contract No. NAS1-15810 while they were in residence at the Institute for Computer Applications in Science and Engineering, NASA Langley Research Center, Hampton, VA 23665, USA 相似文献
16.
This paper is devoted to a class of inverse problems for a nonlinear parabolic differential equation. The unknown coefficient of the equation depends on the gradient of the solution and belongs to a set of admissible coefficients. It is proved that the convergence of solutions for the corresponding direct problems continuously depends on the coefficient convergence. Based on this result the existence of a quasisolution of the inverse problem is obtained in the appropriate class of admissible coefficients. 相似文献
17.
18.
Analytical solutions of the Navier–Stokes equations for the fully developed laminar flow in a cylindrical annulus, when an oscillating circumferential pressure gradient is imposed (finite gap oscillating Dean flow), are presented. The solution for the case of steady flow, which has been given by Goldstein, is obtained as a limit case of the oscillating flow when the frequency of the oscillating pressure gradient tends to zero. The pulsating flow solution is obtained by the superposition of the constant and oscillating pressure gradient solutions. 相似文献
19.
Summary A new ideal metric of orderr>1 is introduced on
k
and a thorough analysis of its metric properties is given. In comparison to the known ideal metric of Zolotarev this new metric allows estimates from above by pseudo difference moments and thus allows applications to stable limit theorems. As applications we give the right order Berry-Esséen type result in the stable case, obtain the limiting behaviour of multivariate summability methods and discuss the approximation problem by compound Poisson distributions.Research supported by NATO GRANT CRG 900 798 and by a DFG Grant 相似文献
20.
Transformation of three-dimensional regions onto rectangular regions by elliptic systems 总被引:2,自引:0,他引:2
Summary A transformation method is developed which may be used to solve various types of boundary value problems on three-dimensional regions with an arbitrary boundary. The implementation of the method is illustrated in the solution of a potential flow problem. All computations are performed on a cubic mesh in a rectangular region.This report was prepared as a result of work performed under NASA Contract No. NAS1-14101 while the first author was in residence at ICASE, NASA Langley Research Center, Hampton, VA 23665, USA 相似文献