In this paper, we consider retrieving individual wave components in a multi-directional sea wave model. To solve this problem, a currently and commonly used method is three-dimensional discrete Fourier transform (3D DFT) on the radar image sequence. However, the uniform frequency and the uniform wavenumber in a wavenumber frequency domain can not always strictly satisfy the dispersion relation,...

tacrine (9-amino-1,2,3,4-tetrahydroacridine) as a reversible inhibitor of acetylcholinesterase (ache),was the first drug for the symptomatic treatment of alzheimer’s disease (ad). nmr structuredetermination still presents some considerable challenges: the method is limited to systems ofrelatively small molecular mass, data collection times are long, data analysis remains a lengthyprocedure, and...

Although most noise reduction algorithms are critically dependent on the noise power spectral density (PSD), most procedures for noise PSD estimation fail to obtain good estimates in nonstationary noise conditions. Recently, a DFT-subspace-based method was proposed which improves noise PSD estimation under these conditions. However, this approach is based on eigenvalue decompositions per DFT bi...

In this paper, we evaluate semiempirical methods (AM1, PM3, and ZINDO), HF and DFT (B3LYP) in different basis sets to determine which method best describes the sign and magnitude of the geometrical parameters of artemisinin in the region of the endoperoxide ring compared to crystallographic data. We also classify these methods using statistical analysis. The results of PCA were based on three m...

This paper addresses the estimation of carrier frequency for cyclostationary AM, BPSK, and QPSK signals in the presence of interfering signals and α-stable impulsive noise. The performance of conventional DFT algorithms suffers from severe degradation in impulsive noise environments. By fusing cyclostationarity and fractional lower-order statistics, we introduce a signal selective carrier frequ...

The discrete Fourier transform (DFT) has become a main method of the harmonic analysis because it can be easily implemented in embedded system, but the conventional DFT is afflicted by the spectral leakage and the picket fence effect (PFE) in the asynchronous sampling. In this paper, the frequency-domain estimation method of the harmonic parameters, which is based on the windowing interpolated ...

Since its formal inception in 1964-1965, Kohn-Sham density-functional theory (KS-DFT) has become the most popular electronic structure method in computational physics and chemistry. Its popularity stems from its beautifully simple conceptual framework and computational elegance. The rise of KS-DFT in chemical physics began in earnest in the mid 1980s, when crucial developments in its exchange-c...

We compare the performance of four recently developed DFT methods (MPW1B95, MPWB1K, PW6B95, and PWB6K) and two previous, generally successful DFT methods (B3LYP and B97-1) for the calculation of stacking interactions in six nucleic acid bases complexes and five amino acid pairs and for the calculation of hydrogen bonding interactions in two Watson-Crick type base pairs. We found that the four n...

Reconstruction of signals or images from a few discrete Fourier transform (DFT) values has applications in MRI and SAR. Many real-world signals can be sparsified by an invertible transformation, such as wavelets, into a sparse (mostly zero, with K nonzero values at unknown locations) signal. This Ksparse signal can be reconstructed using the K lowestfrequency DFT values using Prony’s method or ...