Applied Mathematics Letters, vol.23, no.7, pp.812-817, 2010 (SCI-Expanded, Scopus)
In this work we prove approximation theorems for certain positive linear operators via Ditzian-Totik moduli Ω2,Φ (f, ·) of second order where the step-weights are functions whose squares are concave. The results obtained are applied to the q-Lupaş-Bernstein operators, the Ω, q-Bernstein operators and the convergence of the iterates of the q-Bernstein polynomials. © 2010 Elsevier Ltd. All rights reserved.