نتایج جستجو برای: مطالعه dft
تعداد نتایج: 297438 فیلتر نتایج به سال:
Dispersive Fourier transformation (DFT) maps the broadband spectrum of an ultrashort optical pulse into a time stretched waveform with its intensity profile mirroring the spectrum using chromatic dispersion. Owing to its capability of continuous pulse-by-pulse spectroscopic measurement and manipulation, DFT has become an emerging technique for ultrafast signal generation and processing, and hig...
in the present work, dft calculations are employed to obtain the optimized structures of 4-acyl pyrazolone tautomers (19 tautomers) using b3lyp/6-311++g** calculations. inaddition, molecular parameters, ir frequencies and relative energies are extracted for alltautomers. the existence of aromatic ring, keto tautomer (versus enol tautomer), n-h bond(versus c-h bond) and c=n double bond (versus n...
density functional (dft) calculations at m05-2x/aug-cc-pvdz level were used to analyze the interactions between dimethyl sulfoxide (dmso) dimers. the structures obtained have been analyzed with the atoms in molecules (aims) and natural bond orbital (nbo) methodologies. four minima were located on the potential energy surface of the dimers. three types of interactions are observed, ch•••o, ch•••...
in the present work, the electronic properties of titanium were studied in three phases of α, β and ω using the density function theory (dft). the full potential augmented plane wave plus local orbital (flapw+lo) method was applied using the generalized gradient approximation. the calculated total energies showed that omega phase was more stable than the two other phases. the largest electrical...
In this paper an estimator for speech enhancement based on Laplacian Mixture Model has been proposed. The proposed method, estimates the complex DFT coefficients of clean speech from noisy speech using the MMSE estimator, when the clean speech DFT coefficients are supposed mixture of Laplacians and the DFT coefficients of noise are assumed zero-mean Gaussian distribution. Furthermore, the MMS...
ICD patients with elevated defibrillation threshold: clinical behavior and therapeutic alternatives.
BACKGROUND The ideal programming of the implantable cardioverter defibrillator (ICD) shock energy should be at least 10J above the defibrillation threshold (DFT), requiring alternative techniques when the DFT is elevated. OBJECTIVE To assess the clinical behavior of ICD patients with DFT>25J and the efficacy of the chosen therapy. METHODS Patients who had undergone ICD implantation between ...
Density functional theory (DFT) embedding provides a formally exact framework for interfacing correlated wave-function theory (WFT) methods with lower-level descriptions of electronic structure. Here, we report techniques to improve the accuracy and stability of WFT-in-DFT embedding calculations. In particular, we develop spin-dependent embedding potentials in both restricted and unrestricted o...
BACKGROUND AND AIMS Childhood obesity has been associated with high refined sugar intake. The relationship between sucrose intake and development of dental caries has been established. The aim of this study was to determine the association between age-specific body mass index (BMI-for-age) and dental caries in children. MATERIALS AND METHODS In this cross-sectional study a total of 1003 child...
ساختار الکترونی و چگالی حالتهای جزیی و کل در تیتانات باریم مکعبی مورد مطالعه قرار گرفته است. محاسبات با استفاده از روش پتانسیل کامل امواج تخت تقویت شده (fp-lapw) در چارچوب نظریه تابعی چگالی (dft) هوهنبرگ, کوهن و شم با تقریب شیب تعمیم یافته (gga) انجام گرفته است. نتایج حاصل سازگاری خوبی با نتایج تجربی و تئوری بدست آمده از روشهای دیگر دارد.
مقدمه: پوسیدگی دندانی از شایع ترین بیماری های مزمن دوران کودکی است. بعضی از مطالعات تأثیر مخرب سیگار کشیدن فعال و همچنین دود سیگار محیطی را بر پیشرفت پوسیدگی دندانی گزارش نموده اند. هدف از این مطالعه مقایسه میزان پوسیدگی دندانی با استفاده از شاخص های dft و dmft decay-missing-filling-teeth) ) بین کودکان در معرض دود سیگار محیطی و کودکانی که در معرض دود سیگار نیستند، بود. مواد و روش ها: در این تحق...
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