نتایج جستجو برای: مطالعه dft

تعداد نتایج: 297438  

Journal: :Journal of the American College of Cardiology 2002
Gregory P Walcott Cheryl R Killingsworth William M Smith Raymond E Ideker

OBJECTIVES The goal of this study was to determine if the defibrillation threshold (DFT) after spontaneous ventricular fibrillation (VF) secondary to acute ischemia differs from the DFT for electrically induced VF in the absence of ischemia in anesthetized, closed-chest dogs and pigs. BACKGROUND The efficacy of external defibrillators has been tested mainly in animals and humans using E-VF, y...

In this paper an estimator of speech spectrum for speech enhancement based on Laplacian Mixture Model has been proposed. We present an analytical solution for estimating the complex DFT coefficients with the MMSE estimator when the clean speech DFT coefficients are mixture of Laplacians distributed. The distribution of the DFT coefficients of noise are assumed zero-mean Gaussian.The drived MMSE...

ژورنال: :international journal of new chemistry 0

in this study, the drug atenolol on c60 fullerene were the drug and its derivatives were optimized fullerene. nbo and nmr for complex computations required in the hf/6-31g (d) and b3lyp/6-31g (d) quantum chemistry method was used. mechanical quantum calculations in theory level of b3lyp/6-31g were performed on structure of atenolol and nano fullerene atenolol with different positions of linking...

Journal: :Journal of physics. Condensed matter : an Institute of Physics journal 2012
Duy Le Abdelkader Kara Elsebeth Schröder Per Hyldgaard Talat S Rahman

The physisorption of the nucleobases adenine (A), cytosine (C), guanine (G), thymine (T), and uracil (U) on graphene is studied using several variants of the density functional theory (DFT): the generalized gradient approximation with the inclusion of van der Waals interaction (vdW) based on the TS approach (Tkatchenko and Scheffer 2009 Phys. Rev. Lett. 102 073005) and our simplified version of...

Journal: :Annual review of physical chemistry 2012
M E Casida M Huix-Rotllant

The classic density-functional theory (DFT) formalism introduced by Hohenberg, Kohn, and Sham in the mid-1960s is based on the idea that the complicated N-electron wave function can be replaced with the mathematically simpler 1-electron charge density in electronic structure calculations of the ground stationary state. As such, ordinary DFT cannot treat time-dependent (TD) problems nor describe...

Journal: :CoRR 2013
Vilnis Liepins

This summary of the doctoral thesis [8] is created to emphasize the close connection of the proposed spectral analysis method with the Discrete Fourier Transform (DFT), the most extensively studied and frequently used approach in the history of signal processing. It is shown that in a typical application case, where uniform data readings are transformed to the same number of uniformly spaced fr...

Journal: :Journal of chemical theory and computation 2013
Miquel Huix-Rotllant Michael Filatov Samer Gozem Igor Schapiro Massimo Olivucci Nicolas Ferré

In the quest for a cost-effective level of theory able to describe a large portion of the ground and excited potential energy surfaces of large chromophores, promising approaches are rooted in various approximations to the exact density functional theory (DFT). In the present work, we investigate how generalized Kohn-Sham DFT (GKS-DFT), time-dependent DFT (TDDFT), and spin-restricted ensemble-D...

2010
Sony Jacob Victorio Pidlaoan Jaspreet Singh Aditya Bharadwaj Mehul B Patel Antonio Carrillo

Defibrillation threshold (DFT) testing has traditionally been an integral part of implantable cardioverter defibrillator (ICD) implantation. With the increasing number of patients receiving ICDs, physicians are encountering high DFT more often than before. Tackling the problem of high DFT, warrants an in-depth understanding of the science of defibrillation including the key electrophysiological...

Journal: :CSSP 2015
I. Mamatha T. S. B. Sudarshan Shikha Tripathi Nikhil Bhattar

Realization of N-point Discrete Fourier Transform (DFT) using one-dimensional or two-dimensional systolic array structures have been developed for power of two DFT sizes. DFT algorithm, which can be represented as a triple -matrix product, can be realized by decomposing N into smaller lengths. Triple matrix product form of representation enables to map the Npoint DFT on a 2-D systolic array. In...

2007
Sergey Aleksandrovich Varganov Ryan M. Olson Mark S. Gordon Horia Metiu Sergey A. Varganov

Presented in this work are the results of a quantum chemical study of oxygen adsorption on small Aun and Au−n (n=2,3) clusters. Density functional theory(DFT), second order perturbation theory (MP2), and singles and doubles coupled clustertheory with perturbative triples [CCSD(T)] methods have been used to determine the geometry and the binding energy of oxygen to Aun. The multireference charac...

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