Ruiz-Medina M.D.,University of Granada |
Porcu E.,University George August Goettingen |
Fernandez-Pascual R.,University Jan
Probabilistic Engineering Mechanics | Year: 2011
The functional statistical framework is considered to address the problem of least-squares estimation of the realizations of fractal and long-range dependence Gaussian random signals, from the observation of the corresponding response surface. The statistical methodology applied is based on the functional regression model. The geometrical properties of the separable Hilbert spaces of functions, where the response surface and the signal of interest lie, are considered for removing the ill-posed nature of the estimation problem, due to the non-locality of the integro-pseudodifferential operators involved. Specifically, the local and asymptotic properties of the spectra of fractal and long-range dependence random fields in the Linnik-type, Dagum-type and auxiliary families are analyzed to derive a stable solution to the associated functional estimation problem. Their pseudodifferential representation and Reproducing Kernel Hilbert Space (RKHS) characterization are also derived for describing the geometrical properties of the spaces where the functional random variables involved in the corresponding regression problem can be found. © 2010 Elsevier Ltd. All rights reserved.
Density functional theory study of the optical and electronic properties of oligomers based on phenyl-ethynyl units linked to triazole, thiadiazole, and oxadiazole rings to be used in molecular electronics
Garzon A.,University Jan |
Granadino-Roldan J.M.,University Jan |
Moral M.,University Jan |
Garcia G.,University Jan |
And 4 more authors.
Journal of Chemical Physics | Year: 2010
In the present work, we have studied from a theoretical perspective the geometry and electronic properties of the series of related compounds 2,5-bis(phenylethynyl)-1,3,4-thiadiazole, 2,5-bis(phenylethynyl)-1,3,4- oxadiazole, and 2,5-bis(phenylethynyl)-1,2,4-triazole as candidates for electron-conducting polymers and compounds with desirable (opto)electronic properties. The effect of the ethynyl group (-C≡C-) on the structure and electronic properties was also studied. The influence of planarity on electrical conductivity has been studied by a natural-bond-orbital analysis. The (opto)electronic properties and conducting capability were investigated through the highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap, excitation energy, bond length alternation, LUMO energy, electron affinities, and intramolecular reorganization energy. Finally, the evolution of some properties such as optical bandgap and electron affinity with the increase of the number of repeat units in the oligomer chain has been checked. © 2010 American Institute of Physics.
Angel Cid J.,University Jan |
Pouso O.L.,University of Santiago de Compostela |
Pouso R.L.,University of Santiago de Compostela
Nonlinear Analysis: Real World Applications | Year: 2011
We prove the existence of infinitely many solutions for a second-order singular initial value problem between given lower and upper solutions. Our study is motivated by a singular problem which arises in the field of nonlinear massive gravity. Moreover, we also discuss the global behavior of solutions of the motivating problem. Our arguments lean at some steps on lower and upper solutions with corners in their graphs, thus showing the applicability of this more general definition of lower and upper solutions in the analysis of a concrete mathematical model. © 2011 Elsevier Ltd. All rights reserved.