نتایج جستجو برای: dft computation

تعداد نتایج: 163405  

2009
Athipat Limmanee Chalie Charoenlarpnopparut

Under the restriction of the frequency usage license, there are limited radio frequency ranges that can be used. However, the cost and equipments for monitoring and detecting the violation of licensed frequency bands can be expensive and complicated. Therefore, this paper proposes the design of Power Spectral Monitoring System for monitoring and detecting the signal whose frequency exceeds the ...

1998

This paper is mainly intended as survey article on construction of fast algorithms for the computation of the discrete Fourier transform (DFT) and discrete Hartley transform (DHT), all in relation to discrete linear and cyclic convolution which are fundamental operations in many data processing tasks. The exposition prefers purely algebraic approach to explain the basic ideas in concise but cle...

Journal: :Journal of computational chemistry 2006
Mihail Atanasov Peter Comba Bodo Martin Vera Müller Gopalan Rajaraman Heidi Rohwer Steffen Wunderlich

Various DFT and ab initio methods, including B3LYP, HF, SORCI, and LF-density functional theory (DFT), are used to compute the structures, relative stabilities, spin density distributions, and spectroscopic properties (electronic and EPR) of the two possible isomers of the copper(II) complexes with derivatives of a rigid tetradentate bispidine ligand with two pyridine and two tertiary amine don...

1999
Cagatay Candan M. Alper Kutay Haldun M. Özaktas

We propose and consolidate a definition of the discrete fractional Fourier transform that generalizes the discrete Fourier transform (DFT) in the same sense that the continuous fractional Fourier transform generalizes the continuous ordinary Fourier transform. This definition is based on a particular set of eigenvectors of the DFT matrix, which constitutes the discrete counterpart of the set of...

Journal: :Computers & Mathematics with Applications 2013
Alvise Sommariva

The main purpose of this paper is to compute the weights of Clenshaw-Curtis and Fejér type quadrature rules via DCT and DST, for general weight functions w. The approach is different from that used by Waldvogel in [25], where the author considered the computation of these sets only for the Legendre weight w ≡ 1 using DFT arguments.

Journal: :IEEE Trans. Acoustics, Speech, and Signal Processing 1990
Yuhang Wu

In some signal processing applications, the input data are real. In this case, the Bruun algorithm for computation of the Discrete Fourier Transform (DFT) is attractive. This correspondence offers a pipeline and a recirculated shuffle network implementation of the Bruun algorithm. The parallel pipeline and recirculated FFT structures are implemented based on the modified perfect shuffle network.

Enaminones are those structures made up three various functional groups including carbonyl, alkeneand amine groups which arelocated along with each other in a conjugate fashion. These compoundsare of much attention due to special characteristics and numerous applications. In the paper, sixvarious enaminone structures were theoretically optimized and after concluding, were compared withequivalen...

Hooriye Yahyaei Neda Hasanzadeh

α-acyloxycarboxamides are synthesized from three component Passerini reaction between indane-1,2,3-trione, isocyanides, and thiophenecarboxylic acids in quantitative yields. The structures of the final products were confirmed by IR, 1H and 13C NMR spectroscopy, mass spectrometry, and elemental analysis. The B3LYP/HF calculations for computation of 1H an...

Journal: :Chemical reviews 2003
P Geerlings F De Proft W Langenaeker

It is an understatement to say that the density functional theory (DFT) has strongly influenced the evolution of quantum chemistry during the past 15 years; the term “revolutionalized” is perhaps more appropriate. Based on the famous Hohenberg and Kohn theorems,1 DFT provided a sound basis for the development of computational strategies for obtaining information about the energetics, structure,...

      A novel podand based anion receptor bearing benzimidazole motifs as recognition sites was designed and synthesized by reaction of 1,7-bis(2'-methylbenzoate)-1,4,7-trioxaheptane and phenylenediamine. The binding properties of anionic guest with this receptor were studied using UV-Vis and fluorescence spectroscopy. These studies revealed that this receptor exhibit selective recognition towar...

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