Oscillation of forced impulsive differential equations with pp-Laplacian and nonlinearities given by Riemann-Stieltjes integrals

In this article, we study the oscillation of second order forced impulsive differential equation with $p$-Laplacian and nonlinearities given by Riemann-Stieltjes integrals of the form \begin{equation*} \left( p(t)\phi _{\gamma }\left( x^{\prime }(t)\right) \right) ^{\prime}+q_{0}\left( t\right) \phi _{\gamma }\left( x(t)\right)+\int_{0}^{b}q\left( t,s\right) \phi _{\alpha \left( s\right) }\left(x(t)\right) d\zeta \left(s\right) =e(t), t\neq \tau _{k}, \end{equation*} with impulsive conditions \begin{equation*} x\left( \tau _{k}^{+}\right) =\lambda _{k}~x\left( t_{k}\right), x^{\prime }\left( \tau _{k}^{+}\right) =\eta _{k}~x^{\prime }\left( \tau_{k}\right), \end{equation*} where \phi _{\gamma }\left( u\right) :=\left\vert u\right\vert ^{\gamma } \mbox{{\rm sgn}\,}u, $\gamma, b\in \left( 0,\infty \right),$ $\alpha \in C\left[ 0,b\right)$ is strictly increasing such that $0\leq \alpha \left( 0\right) <\gamma <\alpha \left( b-\right)$, and $\left\{ \tau_{k}\right\}_{k\in {\mathbb{N}}}$ is the the impulsive moments sequence. Using the Riccati transformation technique, we obtain sufficient conditions for this equation to be oscillatory

Interval oscillation criteria for nonlinear impulsive differential equations with variable delay

In this paper, the interval qualitative properties of a class of second order nonlinear differential equations are studied. For the hypothesis of delay being variable $\tau(t)$, an "interval delay function" is introduced to estimate the ratio of functions $x(t-\tau(t))$ and $x(t)$ on each considered interval, then Riccati transformation and $H$ functions are applied to obtain interval oscillation criteria. The known results gained by Huang and Feng [Comput. Math. Appl. 59(2010), 18–30] under the assumption of constant delay $\tau$ are developed. Moreover, examples are also given to illustrate the effectiveness and non-emptiness of our results

Forced oscillation of conformable fractional partial delay differential equations with impulses

In this paper, we establish some interval oscillation criteria for impulsive conformable fractional partial delay differential equations with a forced term. The main results will be obtained by employing Riccati technique. Our results extend and improve some results reported in the literature for the classical differential equations without impulses. An example is provided to illustrate the relevance of the new theorems

On steady alternate bars forced by a localized asymmetric drag distribution in erodible channels

Studying the effect of different in-stream fluvial turbines siting on river morphodynamics allowed us to witness the onset of a time-Averaged, large-scale, alternate distortion of bed elevations, which could not be exclusively related to the turbine rotor blockage. The longitudinal profiles of this two-dimensional bathymetric perturbation resemble those of steady fluvial bars. In this contribution we generalize the problem addressing a spatially impulsive, asymmetric distribution of drag force in the channel cross-section. This is experimentally investigated through the deployment of differently sized grids perpendicular to the flow, and analytically explored as a finite perturbation of an open channel flow over an erodible sediment layer, as described by a coupled flow-sediment shallow water equation. The steady solutions of this fluvial morphodynamic problem, physically represented by alternate bars scaling with the channel width, highlight the importance of the resonant conditions in defining the spatial extent of the bed deformation. The equations further suggest that in very shallow flows any asymmetric obstruction may lead to an upstream propagation of the steady bars, consistent with previous studies on the effects of channel curvature. In broad terms, this study provides the preliminary framework to control the onset of river meandering through imposed finite perturbations of the cross-section. In a more applied sense, it provides a tool to predict non-local scour-deposition patterns associated with the deployment of energy converters or other flow obstructions

Nonlinear vibrations of 3D beams

This work was supported by Fundação para a Ciência e a Tecnologia, through the scholarship SFRH/BD/35821/2007Tese de doutoramento. Engenharia Mecânica. Faculdade de Engenharia. Universidade do Porto. 201