16,184 research outputs found
Two-parameter differential calculus on the h-superplane
We introduce a noncommutative differential calculus on the two-parameter
-superplane via a contraction of the (p,q)-superplane. We manifestly show
that the differential calculus is covariant under
transformations. We also give a two-parameter deformation of the
(1+1)-dimensional phase space algebra.Comment: 14 page
Differential Geometry of the q-plane
Hopf algebra structure on the differential algebra of the extended -plane
is defined. An algebra of forms which is obtained from the generators of the
extended -plane is introduced and its Hopf algebra structure is given.Comment: 9 page
Two-parameter nonstandard deformation of 2x2 matrices
We introduce a two-parameter deformation of 2x2 matrices without imposing any
condition on the matrices and give the universal R-matrix of the nonstandard
quantum group which satisfies the quantum Yang-Baxter relation. Although in the
standard two-parameter deformation the quantum determinant is not central, in
the nonstandard case it is central. We note that the quantum group thus
obtained is related to the quantum supergroup by a
transformation.Comment: 10 page
Two-Parameter Differential Calculus on the h-Exterior Plane
We construct a two-parameter covariant differential calculus on the quantum
-exterior plane. We also give a deformation of the two-dimensional fermionic
phase space.Comment: 7 page
Image resolution enhancement using dual-tree complex wavelet transform
In this letter, a complex wavelet-domain image resolution enhancement algorithm based on the estimation of wavelet coefficients is proposed. The method uses a forward and inverse dual-tree complex wavelet transform (DT-CWT) to construct a high-resolution (HR) image from the given low-resolution (LR) image. The HR image is reconstructed from the LR image, together with a set of wavelet coefficients, using the inverse DT-CWT. The set of wavelet coefficients is estimated from the DT-CWT decomposition of the rough estimation of the HR image. Results are presented and discussed on very HR QuickBird data, through comparisons between state-of-the-art resolution enhancement methods
Range separated hybrid exchange-correlation functional analyses of W and/or N(S) (co)doped anatase TiO_2
Electronic properties and atomic structures of W, N, S, W/N, and W/S dopings
of anatase TiO_2 have been systematically investigated using the density
functional theory (DFT). The exchange and correlation effects have been treated
with Heyd, Scuseria and Ernzerhof (HSE) hybrid functional. Mixing traditional
semi-local and non-local screened Hartree-Fock (HF) exchange energies, the HSE
method corrects the band gap and also improves the description of anion/cation
derived gap states. Enhanced charge carrier dynamics, observed for W/N codoped
titania, can partly be explained by the passivative modifications of N 2p and W
5d states on its electronic structure. Following this trend we have found an
apparent band gap narrowing of 1.03 eV for W/S codoping. This is due to the
large dispersion of S 3p states at the valance band (VB) top extending its edge
to higher energies and Ti--S--W hybridized states appearing at the bottom of
the conduction band (CB). W/S-TiO_2 might show strong visible light response
comparable to W/N codoped anatase catalysts.Comment: 8 pages, 5 figures and 3 table
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