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Schrödinger Operator on the Zigzag Half-Nanotube in Magnetic Field

A. Iantchenko, E. Korotyaev (2010)

Mathematical Modelling of Natural Phenomena

We consider the zigzag half-nanotubes (tight-binding approximation) in a uniform magnetic field which is described by the magnetic Schrödinger operator with a periodic potential plus a finitely supported perturbation. We describe all eigenvalues and resonances of this operator, and theirs dependence on the magnetic field. The proof is reduced to the analysis of the periodic Jacobi operators on the half-line with finitely supported perturbations.

Second order boundary value problems with sign-changing nonlinearities and nonhomogeneous boundary conditions

John R. Graef, Lingju Kong, Qingkai Kong, Bo Yang (2011)

Mathematica Bohemica

The authors consider the boundary value problem with a two-parameter nonhomogeneous multi-point boundary condition u ' ' + g ( t ) f ( t , u ) = 0 , t ( 0 , 1 ) , u ( 0 ) = α u ( ξ ) + λ , u ( 1 ) = β u ( η ) + μ . C r i t e r i a f o r t h e e x i s t e n c e o f n o n t r i v i a l s o l u t i o n s o f t h e p r o b l e m a r e e s t a b l i s h e d . T h e n o n l i n e a r t e r m f ( t , x ) m a y t a k e n e g a t i v e v a l u e s a n d m a y b e u n b o u n d e d f r o m b e l o w . C o n d i t i o n s a r e d e t e r m i n e d b y t h e r e l a t i o n s h i p b e t w e e n t h e b e h a v i o r o f f ( t , x ) / x f o r x n e a r 0 a n d ± , a n d t h e s m a l l e s t p o s i t i v e c h a r a c t e r i s t i c v a l u e o f a n a s s o c i a t e d l i n e a r i n t e g r a l o p e r a t o r . T h e a n a l y s i s m a i n l y r e l i e s o n t o p o l o g i c a l d e g r e e t h e o r y . T h i s w o r k c o m p l e m e n t s s o m e r e c e n t r e s u l t s i n t h e l i t e r a t u r e . T h e r e s u l t s a r e i l l u s t r a t e d w i t h e x a m p l e s .

Second order BVPs with state dependent impulses via lower and upper functions

Irena Rachůnková, Jan Tomeček (2014)

Open Mathematics

The paper deals with the following second order Dirichlet boundary value problem with p ∈ ℕ state-dependent impulses: z″(t) = f (t,z(t)) for a.e. t ∈ [0, T], z(0) = z(T) = 0, z′(τ i+) − z′(τ i−) = I i(τ i, z(τ i)), τ i = γ i(z(τ i)), i = 1,..., p. Solvability of this problem is proved under the assumption that there exists a well-ordered couple of lower and upper functions to the corresponding Dirichlet problem without impulses.

Second order nonlinear differential equations with linear impulse and periodic boundary conditions

Aydin Huseynov (2011)

Applications of Mathematics

In this study, we establish existence and uniqueness theorems for solutions of second order nonlinear differential equations on a finite interval subject to linear impulse conditions and periodic boundary conditions. The results obtained yield periodic solutions of the corresponding periodic impulsive nonlinear differential equation on the whole real axis.

Semigroup Analysis of Structured Parasite Populations

J. Z. Farkas, D. M. Green, P. Hinow (2010)

Mathematical Modelling of Natural Phenomena

Motivated by structured parasite populations in aquaculture we consider a class of size-structured population models, where individuals may be recruited into the population with distributed states at birth. The mathematical model which describes the evolution of such a population is a first-order nonlinear partial integro-differential equation of hyperbolic type. First, we use positive perturbation arguments and utilise results from the spectral...

Semigroups generated by convex combinations of several Feller generators in models of mathematical biology

Adam Bobrowski, Radosław Bogucki (2008)

Studia Mathematica

Let be a locally compact Hausdorff space. Let A i , i = 0,1,...,N, be generators of Feller semigroups in C₀() with related Feller processes X i = X i ( t ) , t 0 and let α i , i = 0,...,N, be non-negative continuous functions on with i = 0 N α i = 1 . Assume that the closure A of k = 0 N α k A k defined on i = 0 N ( A i ) generates a Feller semigroup T(t), t ≥ 0 in C₀(). A natural interpretation of a related Feller process X = X(t), t ≥ 0 is that it evolves according to the following heuristic rules: conditional on being at a point p ∈ , with probability α i ( p ) , the process...

Shape-preserving properties and asymptotic behaviour of the semigroup generated by the Black-Scholes operator

Antonio Attalienti, Ioan Rasa (2008)

Czechoslovak Mathematical Journal

The paper is devoted to a careful analysis of the shape-preserving properties of the strongly continuous semigroup generated by a particular second-order differential operator, with particular emphasis on the preservation of higher order convexity and Lipschitz classes. In addition, the asymptotic behaviour of the semigroup is investigated as well. The operator considered is of interest, since it is a unidimensional Black-Scholes operator so that our results provide qualitative information on the...

Sharp estimates for the Ornstein-Uhlenbeck operator

Giancarlo Mauceri, Stefano Meda, Peter Sjögren (2004)

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze

Let be the Ornstein-Uhlenbeck operator which is self-adjoint with respect to the Gauss measure γ on d . We prove a sharp estimate of the operator norm of the imaginary powers of on L p ( γ ) , 1 < p < ...

Signals generated in memristive circuits

Artur Sowa (2012)

Nanoscale Systems: Mathematical Modeling, Theory and Applications

Signals generated in circuits that include nano-structured elements typically have strongly distinct characteristics, particularly the hysteretic distortion. This is due to memristance, which is one of the key electronic properties of nanostructured materials. In this article, we consider signals generated from a memrsitive circuit model. We demonstrate numerically that such signals can be efficiently represented in certain custom-designed nonorthogonal bases. The proposed method ensures that the...

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