7 research outputs found
Detection and Analysis of the D esigned Circuit for Ambulatory ECG Electrical Characteristic Points
[[sponsorship]]IEEE[[conferencetype]]國際[[conferencedate]]20150606~20150608[[booktype]]電子版[[iscallforpapers]]Y[[conferencelocation]]台灣/台北 國立臺灣科技大
Chirp-wave Expansion of the Electron Wavefunctions in Atoms
The description of the electron wavefunctions in atoms is generalized to the
fractional Fourier series. This method introduces a continuous and infinite
number of chirp basis sets with linear variation of the frequency to expand the
wavefunctions, in which plane-waves are a special case. The chirp
characteristics of each basis set can be adjusted through a single parameter.
Thus, the basis set cutoff can be optimized variationally. The approach is
tested with the expansion of the electron wavefunctions in atoms, and it is
shown that chirp basis sets substantially improve the convergence in the
description of the electron density. We have found that the natural
oscillations of the electron core states are efficiently described in
chirp-waves
Super-Resolution in Phase Space
This work considers the problem of super-resolution. The goal is to resolve a
Dirac distribution from knowledge of its discrete, low-pass, Fourier
measurements. Classically, such problems have been dealt with parameter
estimation methods. Recently, it has been shown that convex-optimization based
formulations facilitate a continuous time solution to the super-resolution
problem. Here we treat super-resolution from low-pass measurements in Phase
Space. The Phase Space transformation parametrically generalizes a number of
well known unitary mappings such as the Fractional Fourier, Fresnel, Laplace
and Fourier transforms. Consequently, our work provides a general super-
resolution strategy which is backward compatible with the usual Fourier domain
result. We consider low-pass measurements of Dirac distributions in Phase Space
and show that the super-resolution problem can be cast as Total Variation
minimization. Remarkably, even though are setting is quite general, the bounds
on the minimum separation distance of Dirac distributions is comparable to
existing methods.Comment: 10 Pages, short paper in part accepted to ICASSP 201
Diagnosis of Induction Motor Faults in the Fractional Fourier Domain
[EN] Motor current signature analysis (MCSA) is a well-established method for the diagnosis of induction motor faults. It is based on the analysis of the spectral content of a motor current, which is sampled while a motor runs in steady state, to detect the harmonic components that characterize each type of fault. The Fourier transform (FT) plays a prominent role as a tool for identifying these spectral components. Recently, MCSA has also been applied during the transient regime (TMCSA) using the whole transient speed range to create a unique stamp of each harmonic as it evolves in the time-frequency plane. This method greatly enhances the reliability of the diagnostic process compared with the traditional method, which relies on spectral analysis at a single speed. However, the FT cannot be used in this case because the fault harmonics are not stationary signals. This paper proposes the use of the fractional FT (FrFT) instead of the FT to perform TMCSA. This paper also proposes the optimization of the FrFT to generate a spectrum where the frequency-varying fault harmonics appear as single spectral lines and, therefore, facilitate the diagnostic process. A discrete wavelet transform (DWT) is used as a conditioning tool to filter the motor current prior to its processing by the FrFT. Experimental results that are obtained with a 1.1-kW three-phase squirrel-cage induction motor with broken bars are presented to validate the proposed method.This work was supported by the European Community's Seventh Framework Program FP7/2007-2013 under Grant Agreement 224233 (Research Project PRODI "Power Plant Robustification Based on Fault Detection and Isolation Algorithms"). The Associate Editor coordinating the review process for this paper was Dr. Subhas Mukhopadhyay.Pineda-Sanchez, M.; Riera-Guasp, M.; Antonino-Daviu, J.; Roger-Folch, J.; Perez-Cruz, J.; Puche-Panadero, R. (2010). Diagnosis of Induction Motor Faults in the Fractional Fourier Domain. IEEE Transactions on Instrumentation and Measurement. 59(8):2065-2075. https://doi.org/10.1109/TIM.2009.2031835S2065207559
Sampling and Super-resolution of Sparse Signals Beyond the Fourier Domain
Recovering a sparse signal from its low-pass projections in the Fourier
domain is a problem of broad interest in science and engineering and is
commonly referred to as super-resolution. In many cases, however, Fourier
domain may not be the natural choice. For example, in holography, low-pass
projections of sparse signals are obtained in the Fresnel domain. Similarly,
time-varying system identification relies on low-pass projections on the space
of linear frequency modulated signals. In this paper, we study the recovery of
sparse signals from low-pass projections in the Special Affine Fourier
Transform domain (SAFT). The SAFT parametrically generalizes a number of well
known unitary transformations that are used in signal processing and optics. In
analogy to the Shannon's sampling framework, we specify sampling theorems for
recovery of sparse signals considering three specific cases: (1) sampling with
arbitrary, bandlimited kernels, (2) sampling with smooth, time-limited kernels
and, (3) recovery from Gabor transform measurements linked with the SAFT
domain. Our work offers a unifying perspective on the sparse sampling problem
which is compatible with the Fourier, Fresnel and Fractional Fourier domain
based results. In deriving our results, we introduce the SAFT series (analogous
to the Fourier series) and the short time SAFT, and study convolution theorems
that establish a convolution--multiplication property in the SAFT domain.Comment: 42 pages, 3 figures, manuscript under revie