نتایج جستجو برای: محاسبات dft
تعداد نتایج: 30862 فیلتر نتایج به سال:
Introduction It has previously been reported that patients with an implantable cardioverter-defibrillator (ICD) may have a slightly higher defibrillation threshold (DFT) in an upright position compared to a supine position. However, the significance of this and the potential impact on clinical practice remains unclear. We report a case of defibrillation failure caused by an increase in DFT in t...
Recently, discrete Fourier transform (DFT)-based discrete multitone modulation (DMT) systems have been widely applied to various applications. In this paper, we study a broader class of DMT systems using more general unitary matrices instead of DFT matrices. For this class, we will show how to design the optimal DMT systems over frequency-selective channels with colored noise. In addition, asym...
We review density functional theory (DFT) within the Kohn-Sham (KS) and the generalized KS (GKS) frameworks from a theoretical perspective for both time-independent and time-dependent problems. We focus on the use of range-separated hybrids within a GKS approach as a practical remedy for dealing with the deleterious long-range self-repulsion plaguing many approximate implementations of DFT. Thi...
We survey approaches to nonrelativistic density functional theory (DFT) for nuclei using progress toward ab initio DFT for Coulomb systems as a guide. Ab initio DFT starts with a microscopic Hamiltonian and is naturally formulated using orbital-based functionals, which generalize the conventional local-density-plus-gradients form. The orbitals satisfy single-particle equations with multiplicati...
A gold(I) complex with a triphenylphosphine and a monodentate N,N-dimethyldithiocarbamate ligand was synthesized and characterized by Raman spectroscopy and single crystal X-ray diffraction. DFT calculations (Gaussian 09, PBE1PBE/Lanl2dz) were undertaken for a single complex in the gas-phase. The DFT-optimized structure is in good agreement with the crystal structure and the DFT-calculated Rama...
In this study, a dynamic field theory (DFT) based cognitive model of a pilot performing pitch attitude control of a 3 degree of freedom aircraft model is presented. The cognitive model is validated by comparing the pilot model’s pitch attitude hold performance with real flight test results of a human pilot on a real aircraft. A high degree of similarity was observed between the behaviour of the...
Recently DFT based discrete multitone modulation (DMT) systems have been widely applied to various applications. In this paper we study a broader class of DMT systems using more general unitary matrices instead of DFT matrices. For this class we will show how to design the optimal DMT systems over fading channels with colored noise. Examples will be given to show the improvement over the tradit...
We apply the theory of Weyl-Heisenberg frames (WHFs) to oversampled FIR and IIR DFT filter banks (FBs). We show that the polyphase matrices provide a matrix representation of the frame operator, and we find conditions on a DFT FB to provide a WHF expansion. We also show that paraunitary and biorthogonal DFT FBs correspond to tight and exact WHFs, respectively, and that the frame bounds can be o...
BACKGROUND Biphasic waveforms reduce defibrillation threshold (DFT) in a wide variety of models. Although there are several human studies of long-duration, high-tilt biphasic waveform defibrillation, the specific biphasic waveform shape required to achieve optimal DFT reduction is unknown. METHODS AND RESULTS This study tested the effect of single capacitor biphasic waveform tilt modification...
Serious (up to 87 kJ mol(-1)) systematic DFT errors in a series of isodesmic reactions are found to be due to the DFT exchange component, and can be largely corrected by substitution of the DFT exchange energy with the Fock exchange energy.
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