the purpose of this study was the investigation of managers of private publishers of tehran (mppt) in using at information source to acquire information about their organization's external environment and to use it on decision-making. research methods were analytical survey and statistic population 260 managers for research was selected by random sampling methods from morgan table. questio...

The initialand boundary-value problem for the Benjamin-Bona-Mahony (BBM) equation is studied in this paper. The goal is to understand the periodic behavior (termed as eventual periodicity) of its solutions corresponding to periodic boundary condition or periodic forcing. To this aim, we derive a new formula representing solutions of this initialand boundary-value problem by inverting the operat...

where a, c : Z ® R+ are T-periodic functions, f Î C(Z × (0, ∞), R) is T-periodic with respect to t and singular at u = 0. Positive periodic solutions of second-order difference equations have been studied by many authors, see [1-6]. However, in these therein, the nonlinearities are nonsingular, what would happen if the nonlinearity term is singular? It is of interest to note here that singular ...

this paper presents the high order frequency-amplitude relationship for nonlinear transversely vibrating beams with odd and even nonlinearities using homotopy perturbation method with an auxiliary term (hpmat). the governing equations of vibrating buckled beam, beam carrying an intermediate lumped mass and quintic nonlinear beam are investigated to exhibit the reliability and ability of the pro...