Let $R$ be a ring and $M$ a right $R$-module. We call $M$, coretractable relative to $overline{Z}(M)$ (for short, $overline{Z}(M)$-coretractable) provided that, for every proper submodule $N$ of $M$ containing $overline{Z}(M)$, there is a nonzero homomorphism $f:dfrac{M}{N}rightarrow M$. We investigate some conditions under which the two concepts coretractable and $overline{Z}(M)$-coretractable...

circularly-polarized antenna is built based on new siw(substrate integrated waveguide)structure which contains cavity-backed resonator and a conventional polarized ring with twosquare slits in inner and outer ring that differ 90° at position and is proposed for right-handedcircular polarization (rhcp) and fabricated in two separate layers. a broadband impedancebandwidth of 13.9% and a rhcp axia...

circularly-polarized antenna is built based on a new siw (substrate integrated waveguide)structure which contains cavity-backed resonator and a conventional polarized ring with twosquare slits in inner and outer ring that differ 90° at position and is proposed for right-handedcircular polarization (rhcp) and fabricated in two separate layers. a broadband impedancebandwidth of 13.9% and a rhcp a...

From the point of view of homotopy theory a compact Lie group G has the following remarkable combination of properties: (1) G can be given the structure of a finite CW-complex, and (2) there is a pointed space BG and a homotopy equivalence from G to the loop space QB G . Of course the space BG in (2) is the ordinary classifying space of G. In general, a finite complex X together with a chosen e...

It is well–known that every system with commensurable delays can be assigned a finite spectrum by feedback, provided that it is spectrally controllable. In general, the feedback involves distributed delays, and it is defined in terms of a Volterra equation. In the case of multivariable time–delay systems, one would be interested in assigning not only the location of the poles of the closed–loop...

Let G be a finite group. Suppose that Y is a projective algebraic variety over Z (i.e an integral scheme which is projective and flat over Spec (Z)) of relative dimension d. In this paper, we consider finite Galois covers π : X → Y with group G which are everywhere unramified, i.e “G-torsors”. Let F be a G-equivariant coherent sheaf on X. Consider the value of the right derived global section f...

circularly-polarized antenna is built based on new SIW(substrate integrated waveguide)structure which contains cavity-backed resonator and a conventional polarized ring with twosquare slits in inner and outer ring that differ 90° at position and is proposed for right-handedcircular polarization (RHCP) and fabricated in two separate layers. A broadband impedancebandwidth of 13.9% and a RHCP axia...

The Elliott Programme seeks classification of simple, separable, nuclear C∗-algebras via a functor based on K-theory. There are a handful of C∗-algebras, including the Cuntz algebras O2 and O∞, that play particularly important roles in the programme. It is principally in this context that the Jiang-Su algebra Z is regarded as an analogue of O∞, and this thesis proposes an analogue of O2 in a si...