Papers by Hamidreza Rahimi
Optics Communications, 2011
The transmission properties of a double-periodic quasi-crystal containing single-negative materia... more The transmission properties of a double-periodic quasi-crystal containing single-negative materials are investigated with the transfer matrix method and effective medium theory. It is shown that the doubleperiodic quasi-crystal has a single-negative band gap between the zeros of average permittivity and average permeability of the effective medium. These zeros are affected only by the filling factor of the structure, and are independent from the order of the double-periodic quasi-crystal. Moreover, we show that the periodic structure created by repeating the double-periodic quasi-crystal has some omnidirectional band gaps at the single-negative frequency region. The number of such omnidirectional band gap increases by increasing the order of double-periodic quasi-crystal. Then, the structure can be used as a multichannel filter.
Journal of Physics: Conference Series, 2018
Users may download and print one copy of any publication from the public portal for the purpose... more Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Journal of Function Spaces
In this article, applying the concept of a generalized c -distance in cone b -metric spaces over ... more In this article, applying the concept of a generalized c -distance in cone b -metric spaces over Banach algebra with a nonnormal solid cone therein, we establish several common fixed point theorems for two noncontinuous mappings satisfying the Han-Xu-type contraction. Our results are interesting, since they are not equivalent to former well-known results regarding a w t -distance in b -metric spaces while they contain recent results corresponding to a generalized c -distance in cone b -metric spaces.
Axioms
In this work, we define the concept of a generalized c-distance in cone b-metric spaces over a Ba... more In this work, we define the concept of a generalized c-distance in cone b-metric spaces over a Banach algebra and introduce some its properties. Then, we prove the existence and uniqueness of fixed points for mappings satisfying weak contractive conditions such as Han–Xu-type contraction and Cho-type contraction with respect to this distance. Our assertions are useful, since we remove the continuity condition of the mapping and the normality condition for the cone. Several examples are given to support the main results.
Symmetry
In this work, we define the concept of a w-b-cone distance in t v s -cone b-metric spaces which d... more In this work, we define the concept of a w-b-cone distance in t v s -cone b-metric spaces which differs from generalized c-distance in cone b-metric spaces, and we discuss its properties. Our results are significant, since all of the results in fixed point theory with respect to a generalized c-distance can be introduced in the version of w-b-cone distance. Moreover, using Minkowski functionals in topological vector spaces, we prove the equivalence between some fixed point results with respect to a w t -distance in general b-metric spaces and a w-b-cone distance in t v s -cone b-metric spaces.
Journal of Nonlinear Sciences and Applications
In this paper, we consider cone metric type spaces which are introduced as a generalization of sy... more In this paper, we consider cone metric type spaces which are introduced as a generalization of symmetric and metric spaces by Khamsi and Hussain [M.A. Khamsi and N. Hussain, Nonlinear Anal. 73 (2010), 3123-3129]. Then we prove several fixed and periodic point theorems in cone metric type spaces.
Bollettino dell'Unione Matematica Italiana
Miskolc Mathematical Notes
In this paper we consider cone metric type spaces which are introduced as a generalization of sym... more In this paper we consider cone metric type spaces which are introduced as a generalization of symmetric and metric spaces by Khamsi and Hussain in 2010. Then we prove several common fixed point for weakly compatible mappings in cone metric type spaces. All results are proved in the settings of a solid cone, without the assumption of continuity of the mappings.
Acta Mathematica Hungarica
ABSTRACT Abstract. We investigate the amenability of the semigroup algebras �1(S/ρ), where ρ is a... more ABSTRACT Abstract. We investigate the amenability of the semigroup algebras �1(S/ρ), where ρ is a group congruence (not necessarily minimal) on a semigroup S. We relate this to a new notion of amenability of Banach algebras modulo an ideal, to prove a version of Johnson’s theorem for a large class of semigroups, including inverse semigroups, E-inversive semigroup and E-inversive E-semigroups.
Sciprints, 2016
The aim of this paper is to investigate the amenability modulo an ideal of Banach algebraswith em... more The aim of this paper is to investigate the amenability modulo an ideal of Banach algebraswith emphasis on applications to homological algebras. In doing so, we show that amenability modulo an ideal of A** implies amenability modulo an ideal of A. Finally, for a large class of semigroups, we prove that l1(S)** is amenable modulo Iσ** if and only if an appropriate group homomorphic image of S is finite where Iσ is the closed ideal induced by the least group congruence σ.
Journal of Nonlinear Analysis and Optimization Theory Applications, May 13, 2015
Asian-European Journal of Mathematics, 2015
In this paper, we prove some common fixed point theorems by using the generalized distance in a c... more In this paper, we prove some common fixed point theorems by using the generalized distance in a cone metric space. The results of this paper extend well-known results in the literature.
Ukrainian Mathematical Journal, 2014
We present a generalization of several fixed and common fixed point theorems on the c-distance in... more We present a generalization of several fixed and common fixed point theorems on the c-distance in ordered cone metric spaces. In this way, we improve and generalize various results existing in the literature. Наведено узагальнення деяких теорем про нерухому точку та спiльну нерухому точку для c-вiдстанi в упорядкованих конiчних метричних просторах. Таким чином, покращено та узагальнено рiзноманiтнi результати, що наведенi в лiтературi.
ANNALI DELL'UNIVERSITA' DI FERRARA, 2013
In the current work, we obtain the general solution of the following generalized cubic functional... more In the current work, we obtain the general solution of the following generalized cubic functional equation f (x + my) + f (x − my) = 2 2 cos mπ 2 + m 2 − 1 f (x) − 1 2 cos mπ 2 + m 2 − 1 f (2x) +m 2 { f (x + y) + f (x − y)} for an integer m ≥ 1. We prove the Hyers-Ulam stability and the superstability for this cubic functional equation by the directed method and a fixed point approach. We also employ the mentioned functional equation to establish the stability of cubic Jordan *-derivations on C *-algebras and J C *-algebras.
Infinite Dimensional Analysis, Quantum Probability and Related Topics, 2014
In this paper we present a family of analysis and synthesis systems of operators with frame-like ... more In this paper we present a family of analysis and synthesis systems of operators with frame-like properties for the range of a bounded operator on a separable Hilbert space. This family of operators is called a Θ–g-frame, where Θ is a bounded operator on a Hilbert space. Θ–g-frames are a generalization of g-frames, which allows to reconstruct elements from the range of Θ. In general, range of Θ is not a closed subspace. We also construct new Θ–g-frames by considering Θ–g-frames for its components. We further study Riesz decompositions for Hilbert spaces, which are a generalization of the notion of Riesz bases. We define the coefficient operators of a Riesz decomposition and we will show that these coefficient operators are continuous projections. We obtain some results about stability of Riesz decompositions under small perturbations.
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Papers by Hamidreza Rahimi