Upper and Lower Bounds for Special Eigenvalues

1959 ◽  
Vol 26 (2) ◽  
pp. 246-250
Author(s):  
F. C. Appl ◽  
C. F. Zorowski
Keyword(s):  
Exact Solution ◽  
Power Series ◽  
Lower Bounds ◽  
Comparison Theorem ◽  
Eigenvalue Problems ◽  
Buckling Load ◽  
Upper And Lower Bounds ◽  
Elastic Buckling ◽  
Variable Section ◽  
Exact Eigenvalue

Abstract A method for finding upper and lower bounds for the fundamental eigenvalue in special eigenvalue problems is presented. The method is systematic and is shown to provide convergence from above and below to the exact eigenvalue under certain conditions. The method is based on the relatively well-known enclosure or comparison theorem of Collatz, and makes use of a power series to approximate the eigenfunction. The method is applied to two examples concerning the critical-elastic buckling load of variable-section columns with pinned ends. Results for the first example compare well with the exact solution, which is known; the second example is presented as an addition to the literature.

Determination of the Buckling Load for Columns of Variable Stiffness

1949 ◽  
Vol 16 (4) ◽  
pp. 406-410
Author(s):  
C. C. Miesse
Keyword(s):  
Lower Bounds ◽  
Axial Loading ◽  
Variable Stiffness ◽  
Buckling Load ◽  
Upper And Lower Bounds ◽  
Variable Section ◽  
Rayleigh Principle

Abstract A method is given for determining both upper and lower bounds on the critical or buckling load for variable-section columns with axial loading. This method, which is an extension of the Rayleigh principle, is illustrated by three examples.

On the Zeros of Power Series with Exponential Logarithmic Coefficients

1981 ◽  
Vol 24 (3) ◽  
pp. 257-271 ◽  
Author(s):  
W. Gawronski ◽  
U. Stadtmüller
Keyword(s):  
Power Series ◽  
Lower Bounds ◽  
Upper And Lower Bounds ◽  
Number Of Zeros ◽  
Logarithmic Coefficients ◽  
Image Position

In this paper we investigate the zeros of power series1for some functions of coefficients A. In particular, we derive upper and lower bounds for the number of zeros of f in its domain of analyticity.

scholarly journals THE UPPER BOUND PROPERTY FOR SOLID MECHANICS OF THE LINEARLY CONFORMING RADIAL POINT INTERPOLATION METHOD (LC-RPIM)

2007 ◽  
Vol 04 (03) ◽  
pp. 521-541 ◽  
Author(s):  
G. Y. ZHANG ◽  
G. R. LIU ◽  
T. T. NGUYEN ◽  
C. X. SONG ◽  
X. HAN ◽  
...  
Keyword(s):  
Exact Solution ◽  
Lower Bounds ◽  
Upper Bound ◽  
Interpolation Method ◽  
Energy Norm ◽  
Upper And Lower Bounds ◽  
Radial Point Interpolation ◽  
Point Interpolation Method ◽  
Elasticity Problems ◽  
Point Interpolation

It has been proven by the authors that both the upper and lower bounds in energy norm of the exact solution to elasticity problems can now be obtained by using the fully compatible finite element method (FEM) and linearly conforming point interpolation method (LC-PIM). This paper examines the upper bound property of the linearly conforming radial point interpolation method (LC-RPIM), where the Radial Basis Functions (RBFs) are used to construct shape functions and node-based smoothed strains are used to formulate the discrete system equations. It is found that the LC-RPIM also provides the upper bound of the exact solution in energy norm to elasticity problems, and it is much sharper than that of LC-PIM due to the decrease of stiffening effect. An effective procedure is also proposed to determine both upper and lower bounds for the exact solution without knowing it in advance: using the LC-RPIM to compute the upper bound, using the standard fully compatible FEM to compute the lower bound based on the same mesh for the problem domain. Numerical examples of 1D, 2D and 3D problems are presented to demonstrate these important properties of LC-RPIM.

On Blasius's equation governing flow in the boundary layer on a flat plate

1973 ◽  
Vol 74 (1) ◽  
pp. 179-184 ◽  
Author(s):  
S. Richardson
Keyword(s):  
Differential Equation ◽  
Boundary Layer ◽  
Power Series ◽  
Lower Bounds ◽  
Unknown Function ◽  
Asymptotic Properties ◽  
Inverse Function ◽  
Upper And Lower Bounds ◽  
Independent Variable ◽  
Original Approach

AbstractThe original approach of Blasius to the solution of the differential equation now associated with his name was to develop the unknown function as a power series. Unfortunately, this series has a limited radius of convergence, so that such a representation is not valid over the whole range of interest. It is shown here that, if we work instead with a particular inverse function, this can be expanded as a power series which converges for all relevant values of the independent variable. Moreover, the number associated with the solution which is of principal physical interest can be expressed in terms of the asymptotic properties of the coefficients of this series. Exploiting this relationship, we find upper and lower bounds for this number in terms of the zeros of two particular families of polynomials.

Harmonic Waves in Layered Composites: New Bounds on Eigenfrequencies

1978 ◽  
Vol 45 (4) ◽  
pp. 829-833 ◽  
Author(s):  
C. O. Horgan ◽  
K.-W. Lang ◽  
S. Nemat-Nasser
Keyword(s):  
Lower Bounds ◽  
Eigenvalue Problems ◽  
Frequency Estimation ◽  
Discontinuous Coefficients ◽  
Upper And Lower Bounds ◽  
Harmonic Waves ◽  
Smooth Coefficients ◽  
Liouville Transformation ◽  
The One ◽  
Elastic Composites

The purpose of this paper is to present new approaches to the problem of wave frequency estimation for harmonic waves in layered elastic composites. Upper and lower bounds are obtained by adapting standard results for eigenvalue problems with smooth coefficients. The one-dimensional eigenvalue problem with discontinuous coefficients of concern here is first transformed by using an analog of the classical Liouville transformation. Upper bounds are obtained by application of a Rayleigh-Ritz technique to the transformed problem. Explicit lower bounds in terms of the coefficients are established. Results are illustrated by numerical examples.

Solution of heat and mass transfer problems with non-linear coefficients

2019 ◽  
Vol 5 (4) ◽  
pp. 10-20
Author(s):  
Boris G. Aksenov ◽  
Yuri E. Karyakin ◽  
Svetlana V. Karyakina
Keyword(s):  
Mass Transfer ◽  
Exact Solution ◽  
Numerical Methods ◽  
Heat And Mass Transfer ◽  
Unknown Function ◽  
Comparison Theorems ◽  
Upper And Lower Bounds ◽  
Maximum Deviation ◽  
Approximate Methods ◽  
Nonmonotonic Dependence

Equations, which have nonlinear nonmonotonic dependence of one of the coefficients on an unknown function, can describe processes of heat and mass transfer. As a rule, existing approximate methods do not provide solutions with acceptable accuracy. Numerical methods do not involve obtaining an analytical expression for the unknown function and require studying the convergence of the algorithm used. The value of absolute error is uncertain. The authors propose an approximate method for solving such problems based on Westphal comparison theorems. The comparison theorems allow finding upper and lower bounds of the unknown exact solution. A special procedure developed for the stepwise improvement of these bounds provide solutions with a given accuracy. There are only a few problems for equations with nonlinear nonmonotonic coefficients for which the exact solution has been obtained. One of such problems, presented in this article, shows the efficiency of the proposed method. The results prove that the proposed method for obtaining bounds of the solution of a nonlinear nonmonotonic equation of parabolic type can be considered as a new method of the approximate analytical solution having guaranteed accuracy. In addition, the proposed here method allows calculating the maximum deviation from the unknown exact solution of the results of other approximate and numerical methods.

scholarly journals On the Generalized Distance Energy of Graphs

Mathematics ◽  
2019 ◽  
Vol 8 (1) ◽  
pp. 17 ◽  
Author(s):  
Abdollah Alhevaz ◽  
Maryam Baghipur ◽  
Hilal A. Ganie ◽  
Yilun Shang
Keyword(s):  
Lower Bounds ◽  
Complete Graph ◽  
Connected Graph ◽  
Distance Matrix ◽  
Wiener Index ◽  
Diagonal Matrix ◽  
Upper And Lower Bounds ◽  
Star Graph ◽  
Extremal Graphs ◽  
Generalized Distance

The generalized distance matrix D α ( G ) of a connected graph G is defined as D α ( G ) = α T r ( G ) + ( 1 − α ) D ( G ) , where 0 ≤ α ≤ 1 , D ( G ) is the distance matrix and T r ( G ) is the diagonal matrix of the node transmissions. In this paper, we extend the concept of energy to the generalized distance matrix and define the generalized distance energy E D α ( G ) . Some new upper and lower bounds for the generalized distance energy E D α ( G ) of G are established based on parameters including the Wiener index W ( G ) and the transmission degrees. Extremal graphs attaining these bounds are identified. It is found that the complete graph has the minimum generalized distance energy among all connected graphs, while the minimum is attained by the star graph among trees of order n.

scholarly journals Hadamard k-fractional inequalities of Fejér type for GA-s-convex mappings and applications

2019 ◽  
Vol 2019 (1) ◽  
Author(s):  
Hui Lei ◽  
Gou Hu ◽  
Zhi-Jie Cao ◽  
Ting-Song Du
Keyword(s):  
Lower Bounds ◽  
Hypergeometric Functions ◽  
Upper And Lower Bounds ◽  
Weighted Inequalities ◽  
Convex Mappings ◽  
Special Means

Abstract The main aim of this paper is to establish some Fejér-type inequalities involving hypergeometric functions in terms of GA-s-convexity. For this purpose, we construct a Hadamard k-fractional identity related to geometrically symmetric mappings. Moreover, we give the upper and lower bounds for the weighted inequalities via products of two different mappings. Some applications of the presented results to special means are also provided.

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