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Existence and Multiplicity of Solutions for Semilinear Elliptic Boundary Value Problems

Description: This thesis studies the existence, multiplicity, bifurcation and the stability of the solutions to semilinear elliptic boundary value problems. These problems are motivated both by the mathematical structure and the numerous applications in fluid mechanics chemical reactions, nuclear reactors, Riemannian geometry and elasticity theory. This study considers the problem for different classes of nonlinearities and obtain the existence and multiplicity of positive solutions.
Date: August 1992
Creator: Gadam, Sudhasree
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Iterative Solution of Linear Boundary Value Problems

Description: The investigation is initially a continuation of Neuberger's work on linear boundary value problems. A very general iterative procedure for solution of these problems is described. The alternating-projection theorem of von Neumann is the mathematical starting point for this study. Later theorems demonstrate the validity of numerical approximation for Neuberger's method under certain conditions. A sampling of differential equations within the scope of our iterative method is given. The numerical… more
Date: August 1983
Creator: Walsh, John Breslin
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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Tables of Characteristic Functions for Solving Boundary-Value Problems of the Wave Equation with Application to Supersonic Interference

Description: Note presenting tables containing 69,000 values of a set of characteristic functions which first arose in problems of supersonic wing-body interference. The tables are useful in problems of supersonic flow involving aerodynamic shapes which are wholly or in part quasi-cylinders or nearly circular cross sections.
Date: February 1957
Creator: Nielsen, Jack N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Two-and Three-Dimensional Unsteady Lift Problems in High-Speed Flight

Description: "The problem of transient lift on two- and three-dimensional wings flying at high speeds is discussed as a boundary-value problem for the classical wave equation. Kirchoff's formula is applied so that the analysis is reduced, just as in the steady state, to an investigation of sources and doublets. The applications include the evaluation of indicial lift and pitching-moment curves for two-dimensional sinking and pitching wings flying at Mach numbers equal to 0, 0.8, 1.0, 1.2 and 2.0" (p. 393).
Date: October 12, 1950
Creator: Lomax, Harvard; Heaslet, Max A.; Fuller, Franklyn B. & Sluder, Loma
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The use of source-sink and doublet distributions extended to the solution of boundary value problems in supersonic flow

Description: Report presenting a direct analogy between the use of source-sink and doublet distributions in the solution of arbitrary boundary value problems in subsonic wing theory and the corresponding problems in supersonic theory. The concept of the "finite part" of an integral is introduced and used in the calculation of the improper integrals associated with supersonic doublet distributions.
Date: January 1948
Creator: Heaslet, Max A. & Lomax, Harvard
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Stability for inhomogeneous difference schemes

Description: Abstract. The Equivalence Theorem of P. Lax is extended to difference schemes for initial-value problems for linear inhomogeneous PDE with linear inhomogeneous boundary values and for boundary-value problems.
Date: July 13, 1960
Creator: Seidman, Thomas I.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Gabor Wave Packet Method to Solve Plasma Wave Equations

Description: A numerical method for solving plasma wave equations arising in the context of mode conversion between the fast magnetosonic and the slow (e.g ion Bernstein) wave is presented. The numerical algorithm relies on the expansion of the solution in Gaussian wave packets known as Gabor functions, which have good resolution properties in both real and Fourier space. The wave packets are ideally suited to capture both the large and small wavelength features that characterize mode conversion problems. T… more
Date: June 18, 2003
Creator: Pletzer, A.; Phillips, C.K. & Smithe, D.N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A three-level BDDC algorithm for Mortar discretizations

Description: In this paper, a three-level BDDC algorithm is developed for the solutions of large sparse algebraic linear systems arising from the mortar discretization of elliptic boundary value problems. The mortar discretization is considered on geometrically non-conforming subdomain partitions. In two-level BDDC algorithms, the coarse problem needs to be solved exactly. However, its size will increase with the increase of the number of the subdomains. To overcome this limitation, the three-level algorith… more
Date: December 9, 2007
Creator: Kim, H. & Tu, X.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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The Effect of Gaps on Pile Reactivity

Description: From abstract: "The variation of the reactivity of a pile as a function of width of a transverse gap is obtained. The method involves first finding the boundary condition satisfied by the flux at the gap face. This, in principle, provides enough information for a complete solution of the pile equations. A method for calculating the reactivity change is presented. The calculated reactivity is compared with experiment and a brief discussion of the validity of the approximations is given."
Date: July 14, 1952
Creator: Tamor, S. & Ergen, W. K.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Progress Report on the Mach Reflection Calculation

Description: "Mathematical methods are being developed for calculations in fluid dynamics. The work to date on the Mach reflection calculation is summarized. In the flow, there are two curved shocks, a slip surface, a plane shock, and rigid walls. The desired solution of the fluid-dynamics equations is stationary in similarity variables; approximate initial data are therefore assumed, with the expectation that the flow will settle down to the desired one asymptotically. The Eulerian equations for the smooth… more
Date: unknown
Creator: Richtmyer, Robert D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Fast Poisson, Fast Helmholtz and fast linear elastostatic solvers on rectangular parallelepipeds

Description: FFT-based fast Poisson and fast Helmholtz solvers on rectangular parallelepipeds for periodic boundary conditions in one-, two and three space dimensions can also be used to solve Dirichlet and Neumann boundary value problems. For non-zero boundary conditions, this is the special, grid-aligned case of jump corrections used in the Explicit Jump Immersed Interface method. Fast elastostatic solvers for periodic boundary conditions in two and three dimensions can also be based on the FFT. From the … more
Date: June 1, 1999
Creator: Wiegmann, A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The use of source-sink and doublet distributions extended to the solution of boundary-value problems in supersonic flow

Description: "A direct analogy is established between the use of source-sink and doublet distributions in the solution of specific boundary-value problems in subsonic wing theory and the corresponding problems in supersonic theory. The correct concept of the "finite part" of an integral is introduced and used in the calculation of the improper integrals associated with supersonic doublet distributions. The general equations developed are shown to include several previously published results and particular e… more
Date: January 1948
Creator: Heaslet, Max A. & Lomax, Harvard
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Multiple solutions for semilinear elliptic boundary value problems

Description: In this paper results concerning a semilinear elliptic boundary value problem are proven. This problem has five solutions when the range of the derivative of the nonlinearity ƒ includes the first two eigenvalues. The existence and multiplicity or radially symmetric solutions under suitable conditions on the nonlinearity when Ω is a ball in R^N.
Date: December 1991
Creator: Cossio, Jorge Ivan
Item Type: Refine your search to only Thesis or Dissertation
Partner: UNT Libraries
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A Finite Difference Scheme for the Neumann and the Dirichlet Problem

Description: "A specific feature of the finite difference scheme proposed is that in it the boundary condition and the differential equation are treated simultaneously. The scheme results from a variational principle of the original differential equation problem, simply by using the Ritz method employing piecewise linear approximation functions. Thus a rather uniform treatment of boundary condition and differential equation will result. The coefficients of the substitute boundary condition will be given as … more
Date: unknown
Creator: Friedrichs, K. O.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Propagation Characteristics of Capillary Ripples, I. The Theory of Velocity Dispersion and Amplitude Attenuation of Plane Capillary Waves on Viscoelastic Films

Description: From abstract: "The boundary value problem for velocity of propagation and attenuation of capillary ripples over viscoelastic surface films is set up and solved from the viewpoint of continuum hydrodynamics. Both soluble and insoluble films are treated. Successive approximation methods are used to derive explicit formulae for velocity of propagation and amplitude attenuation; formulae for these quantities accurate to second order are given for slightly viscoelastic and highly viscoelastic films… more
Date: January 4, 1963
Creator: Hansen, Robert S. & Mann, J. Adin, Jr.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Ductile Fracture of Cracked Steel Plates

Description: A simple relationship between loading for crack initiation, or onset of ductile tear, and crack length is presented for center-cracked plates of mild steel. Formulation of the nonlinear boundary-value problem is based on incremental theory of plasticity for Prandtl-Reuss materials. Quasi-static solutions corresponding to a series of incremental loading conditions are obtained by the method of finite elements. Tests conducted on plates of two types of mild steel agree with numerical results.
Date: October 23, 2001
Creator: Yau, W. F.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Precise Closed-Form Solutions of Some Mixed Boundary Value Problems of Plane Elasticity

Description: Precise solutions are given for the problem of the semi-infinite strip extending from x=0 to x=infinity, stress-free along the edges y= +-1, when the edge x=0 is subject (a) to a quadratic sheer displacement and zero normal stress, (b) to a cubic normal displacement and zero sheer stress. These are the two simplest (non-trivial) end problems of the semi-infinite strip, antisymmetric in y, that may be formulated. The corresponding symmetric problems (a) linear seer displacement and zero normal s… more
Date: 1954
Creator: Horvay, Gabriel, 1908- & Born, J. B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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SEACAS Theory Manuals: Part 1. Problem Formulation in Nonlinear Solid Mechancis

Description: This report gives an introduction to the basic concepts and principles involved in the formulation of nonlinear problems in solid mechanics. By way of motivation, the discussion begins with a survey of some of the important sources of nonlinearity in solid mechanics applications, using wherever possible simple one dimensional idealizations to demonstrate the physical concepts. This discussion is then generalized by presenting generic statements of initial/boundary value problems in solid mechan… more
Date: August 1, 1998
Creator: Attaway, S. W.; Laursen, T. A. & Zadoks, R. I.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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One-Dimensional Leakage-Flow Vibration Instabilities

Description: Simple boundary conditions, pressure losses, and channel geometries necessary for the unstable, rigid-body translational vibrations of the wall of one-dimensional leakage-flow channel are identified. General expressions for the flow damping and stiffness forces acting on the vibrating channel wall are derived and specific results are given for channels with wall friction, point pressure losses, sharp-edged constrictions, and diverging or converging widths. The minimum conditions necessary for d… more
Date: September 1987
Creator: Mulcahy, T. M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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BPERM version 3.0: A 2-D wakepotential/impedance code

Description: BPERM 3.0 is an improved version of a previous release. The main purpose of this version is to make it more user friendly. Following a simple 1-2-3 procedure, one obtains both text and graphical output of the wakepotential and impedance for a given geometry. The calculation is based on a boundary perturbation method, which is significantly faster than numerical simulations. It is accurate when the discontinuities are small. In particular, it works well for tapered structures. 5 refs., 3 figs.
Date: October 1, 1996
Creator: Barts, T. & Chou, W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Proceedings of the Focused Research Program on Spectral Theory and Boundary Value Problems, Vol. 2: Singular Differential Equations

Description: Report on research and exchange of views among 24 mathematicians for investigations of the theory of singular Sturm-Liouville equations, the asymptotic analysis of the Titchmarsh-Weyl m(λ)-coefficient, and the qualitative theory of non-linear differential equations.
Date: September 1988
Creator: Kaper, H. G.; Kwong, Man Kam & Zettl, Anton
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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