we define a new type of spectrum, called δ-approximate spectrum, of an element a in a complex unital banach algebra a and show that the δ-approximate spectrum σ_δ (a) of a is compact. the relation between the δ-approximate spectrum and the usual spectrum is investigated. also an analogue of the classical gleason-kahane-zelazko theorem is established: for each ε>0, there is δ>0 such that if ϕ is...

in this article we study two different generalizations of von neumann regularity, namely strong topological regularity and weak regularity, in the banach algebra context. we show that both are hereditary properties and under certain assumptions, weak regularity implies strong topological regularity. then we consider strong topological regularity of certain concrete algebras. moreover we obtain ...

Certain topological dynamical systems are considered that arise from actions of σ-compact locally compact Abelian groups on compact spaces of translation bounded measures. Such a measure dynamical system is shown to have pure point dynamical spectrum if and only if its diffraction spectrum is pure point.

Bistatic SAR data are more complicated to process than monostatic data because of the versatile sensor geometry and the non-stationary properties of the received data. Recent approaches to the processing of bistatic SAR data have revolved around finding an accurate representation of the two-dimensional spectrum for a point target. In this paper, we review past methods of obtaining the spectrum,...

Radio spectrum has turned into a precious natural resource from free goods due to the rapid development of wireless communication technology. In order to efficiently utilize radio spectrum, a spectrum policy should be enough appropriate to create new industries and new technologies. From this point of view, we have developed a distributed spectrum sensing system which collects dense information...

We characterize the spectrum and essential spectrum of “essentially linear fractional” composition operators acting on the Hardy space H2(U) of the open unit disc U. When the symbols of these composition operators have Denjoy-Wolff point on the unit circle, the spectrum and essential spectrum coincide. Our work permits us to describe the spectrum and essential spectrum of certain associated wei...

in this work, we had examined 7 different types of neutron sources -an isotropic point source, sending 14.1(mev) monoenergetic neutrons ,an spherical source with 30 micron radius sending 14.1 (mev) monoenergetic neutrons, and a 30 micron radius spherical source having gaussian fusion energy spectrum from a d-t fusion, with different bandwidths -1,10,50,100 and 1000 kev and investigated 5 differ...

In this study, we determine the fine spectrum of the matrix operator ∆ defined by an upper triangle double band matrix acting on the sequence space c0 with respect to the Goldberg’s classification. As a new development, we give the approximate point spectrum, defect spectrum and compression spectrum of the matrix operator ∆ on c0. AMS subject classifications: 47A10, 47B37

Dynamic spectrum sharing paradigm is envisaged to meet the growing demand for the Radio Frequency (RF) spectrum. There exist several technical, regulatory, and business impediments for adopting the new paradigm. In this regard, we underscore the need of characterizing and quantifying the use of spectrum by each of the individual transmitters and receivers. We propose MUSE, a methodology to char...