Flat systems, an important subclass of nonlinear control systems introduced via differential-algebraic methods, are defined in a differential geometric framework. We utilize the infinite dimensional geometry developed by Vinogradov and coworkers: a control system is a diffiety, or more precisely, an ordinary diffiety, i.e. a smooth infinite-dimensional manifold equipped with a privileged vector...

A method has been recently proposed for defining an arbitrary number of differential calculi over a given noncommutative associative algebra. As an example a version of quantized space-time is considered here. It is found that there is a natural differential calculus using which the space-time is necessarily flat Minkowski space-time. Perturbations of this calculus are shown to give rise to non...

In this paper‎, ‎we study the class of rings in which every $P$-flat‎ ‎ideal is flat and which will be called $PFF$-rings‎. ‎In particular‎, ‎Von Neumann regular rings‎, ‎hereditary rings‎, ‎semi-hereditary ring‎, ‎PID and arithmetical rings are examples of $PFF$-rings‎. ‎In the context domain‎, ‎this notion coincide with‎ ‎Pr"{u}fer domain‎. ‎We provide necessary and sufficient conditions for‎...

Presented is an evaluation of phase contrast techniques in transmission electron microscopy. The traditional defocus phase contrast is compared to two recently developed phase plate techniques. One is the Zernike phase contrast transmission electron microscope, the other is the Hilbert differential contrast thransmission electron microscope. The imaging characteristics of each technique are dis...

The problem of two-dimensional steady laminar MHD free convection flow over a vertical porous flat plate immersed in porous medium has been studied numerically in the presence of magnetic field and heat generation effect. The resulting momentum, energy and concentration equations have been transformed into a system of ordinary differential equations by using a suitable similarity transformation...

in 2001, s. bulman-fleming et al. initiated the study of three flatness properties (weakly kernel flat, principally weakly kernel flat, translation kernel flat) of right acts $a_{s}$ over a monoid $s$ that can be described by means of when the functor $a_{s} otimes -$ preserves pullbacks. in this paper, we extend these results to$s$-posets and present equivalent descriptions of weakly kernel po...

We investigate the two dimensional free convection and mass transfer flow of an incompressible, viscous and electrically conducting fluid past a continuously moving vertical flat plate in the presence of heat source, thermal diffusion, large suction and the influence of uniform magnetic field applied normal to the flow. Usual similarity transformations are introduced to solve the momentum, ener...

Background and Objectives: Flat breads are the most consumed bread in Iran. Barbari one of the popular ones, is traditional flat leavened Iranian bread and one of the most popular breads consumed in Iran and some other countries in the Middle East. Materials and Methods: The aim of this study was to evaluate the effect of substitution of wheat flour by whole quinoa flour (0-15% substitution) a...

Abstract: Reliability prediction is becoming more and more important for electronics components and devices, such as avionics. In this paper, a grey prediction model based prognostics approach was developed to perform the failure prediction of electronics. The grey prediction model first makes the original data set into a new data set with less randomness in order to find the tendency. Then, hi...