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Positive solutions of third order damped nonlinear differential equations

Miroslav Bartušek, Mariella Cecchi, Zuzana Došlá, Mauro Marini (2011)

Mathematica Bohemica

We study solutions tending to nonzero constants for the third order differential equation with the damping term ( a 1 ( t ) ( a 2 ( t ) x ' ( t ) ) ' ) ' + q ( t ) x ' ( t ) + r ( t ) f ( x ( ϕ ( t ) ) ) = 0 in the case when the corresponding second order differential equation is oscillatory.

Positive solutions to a class of elastic beam equations with semipositone nonlinearity

Qingliu Yao (2010)

Annales Polonici Mathematici

Let h ∈ L¹[0,1] ∩ C(0,1) be nonnegative and f(t,u,v) + h(t) ≥ 0. We study the existence and multiplicity of positive solutions for the nonlinear fourth-order two-point boundary value problem u ( 4 ) ( t ) = f ( t , u ( t ) , u ' ( t ) ) , 0 < t < 1, u(0) = u’(0) = u’(1) =u”’(1) =0, where the nonlinear term f(t,u,v) may be singular at t=0 and t=1. By constructing a suitable cone and integrating certain height functions of f(t,u,v) on some bounded sets, several new results are obtained. In mechanics, the problem models the deflection of...

Positive solutions to a singular fourth-order two-point boundary value problem

Qingliu Yao (2011)

Annales Polonici Mathematici

This paper studies the existence of multiple positive solutions to a nonlinear fourth-order two-point boundary value problem, where the nonlinear term may be singular with respect to both time and space variables. In order to estimate the growth of the nonlinear term, we introduce new control functions. By applying the Hammerstein integral equation and the Guo-Krasnosel'skii fixed point theorem of cone expansion-compression type, several local existence theorems are proved.

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