Octavian G. Mustafa

  1. Asymptotically linear solutions of differential equations via Lyapunov functions.

    Authors: Octavian G. Mustafa, Cemil Tunc
    Subjects: Classical Analysis and ODEs
    Abstract

    We discuss the existence of solutions with oblique asymptotes to a class of
    second order nonlinear ordinary differential equations by means of Lyapunov
    functions. The approach is new in this field and allows for simpler proofs of
    general results regarding Emden-Fowler like equations.

  2. On the asymptotic integration of a class of sublinear fractional differential equations.

    Authors: Dumitru Baleanu, Octavian G. Mustafa
    Subjects: Dynamical Systems
    Abstract

    We estimate the growth in time of the solutions to a class of nonlinear
    fractional differential equations $D_{0+}^{\alpha}(x-x_0) =f(t,x)$ which
    includes $D_{0+}^{\alpha}(x-x_0) =H(t)x^{\lambda}$ with $\lambda\in(0,1)$ for
    the case of slowly-decaying coefficients $H$. The proof is based on the triple
    interpolation inequality on the real line and the growth estimate reads as
    $x(t)=o(t^{a\alpha})$ when $t\to+\infty$ for $1>\alpha>1-a>\lambda>0$.

  3. Oscillatory solutions of some perturbed second order differential equations.

    Authors: Octavian G. Mustafa
    Subjects: Classical Analysis and ODEs
    Abstract

    We discuss the occurrence of oscillatory solutions which decay to 0 as
    $s\to+\infty$ for a class of perturbed second order ordinary differential
    equations. As opposed to other results in the recent literature, the
    perturbation is as small as desired in terms of its improper integrals and it
    is independent of the coefficients of the non-oscillatory unperturbed equation.
    This class of equations reveals thus a new pathology in the theory of perturbed
    oscillations.

  4. Positive solutions of some elliptic differential equations with oscillating nonlinearity.

    Authors: Fahd Jarad, Octavian G. Mustafa, Donal O'Regan
    Subjects: Analysis of PDEs
    Abstract

    We discuss the occurrence of positive solutions which decay to 0 as $|
    x|\to+\infty$ to the differential equation $\Delta u+f(x,u)+g(| x|)x\cdot\nabla
    u=0$, $| x|>R>0$, $x\in\mathbb{R}^{n}$, where $n\geq 3$, $g$ is nonnegative
    valued and $f$ has alternating sign, by means of the comparison method. Our
    results complement several recent contributions from [M. Ehrnstr\"{o}m, O.G.
    Mustafa, On positive solutions of a class of nonlinear elliptic equations,
    Nonlinear Anal. TMA 67 (2007), 1147--1154].

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