Density functional theory (DFT) calculations were performed to investigate adsorptions of vitamin C (Vit) on the surface a fullerene structure (Ful) in gaseous and water–solvated systems. Two models of Vit including OVit and MVit were created based on the original structure of Vit for OVit and methylation of all hydroxyl groups for MVit. All singular and hybrid structures were optimized and the...

Simulating bubbly flows is a very popular topic in CFD. These bubbly flows are governed by the Navier-Stokes equations. In many popular operator splitting formulations for these equations, solving the linear system coming from the discontinuous Poisson equation takes the most computational time, despite of its elliptic origins. Sometimes these singular linear systems are forced to be invertible...

We investigate iterative methods for solving transport linear systems of partially ionized plasmas. We consider the situations of weak and strong magnetic fields as well as nonequilibrium and the linear systems are investigated in their natural constrained singular symmetric form. Stationary iterative techniques are considered with a new more singular formulation of the transport linear systems...

A new method for designing a minimal order perfect functional observers for singular continuous-time linear systems is proposed. Necessary and sufficient conditions for the existence of the minimal order perfect functional observer are established. A procedure for computation of matrices of the observers is derived and illustrated by a numerical example. Key-Words: Design, existence, minimal or...

where T = M-'N. In this article we consider solutions of (1.1) where A is a singular operator and f is such that a solution exists, i.e., consistent singular systems. Singular systems of linear equations appear in many applications, such as when computing the stationary probability distributions of Markov chains [9] or Markov processes [2 ] . These particular applications appear in the analysis...

Notions of externally and internally positive singular discrete-time linear systems are introduced. It is shown that a singular discrete-time linear system is externally positive if and only if its impulse response matrix is non-negative. Sufficient conditions are established under which a single-output singular discrete-time system with matrices in canonical forms is internally positive. It is...

Consider the linear time-invariant singular system Eẋ(t) = Ax(t) + Bu(t) (1) where E, A ∈ Rn×n, B ∈ Rm×n ,C ∈ R p×n and D ∈ R p×m . The system is assumed to be regular det [s E − A] = 0. Systems of the above form are usually called singular systems, descriptor systems, generalized state space systems, semistate systems, etc. It is easily seen that when E is non-singular then (1) may be rewritte...

This paper presents the control of non-regular or singular nonlinear systems applying non-linear predictive controllers. The systems treated here have the relative degree not well defined thus feedback linearization is not applicable due to singularities in the input-output linearizing control law. An alternative controller capable of dealing with non-regular systems is the NCGPC (Nonlinear Con...

Singular nonlinear systems has been of interest to some investigators [4, 12], however no closed-form solution was given in [4, 12]. In some analysis of neural networks, both singular systems [8] and bilinear systems [16] have been used. For singular bilinear systems, Lewis et al. [11] applied the Walsh function (WF) approach for time-invariant singular bilinear systems and Hsiao and Wang [9] u...