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A
theory for multiresolution signal decomposition: the wavelet
representation |
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IEEE
Transactions on Pattern Analysis and Machine Intelligence Vol 11, Nr0. 7, |
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198Jul.
1989, pp. 6p.674-693 |
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Multiresolution
representations are effective for analyzing the information content of |
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images.
The properties of the operator which approximates a signal at a given
resolution |
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were
studied. It is shown that the difference of information between the
approximation of |
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a
signal at the resolutions 2/sup j+1/ and 2/sup j/ (where j is an integer)
can be extracted |
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by
decomposing this signal on a wavelet orthonormal basis of L/sup 2/(R/sup
n/), the |
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vector
space of measurable, square-integrable n-dimensional functions. In L/sup
2/(R), a |
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wavelet
orthonormal basis is a family of functions which is built by dilating and
translating |
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a
unique function psi (x). This decomposition defines an orthogonal
multiresolution |
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representation
called a wavelet representation. It is computed with a pyramidal algorithm |
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based
on convolutions with quadrature mirror filters. Wavelet representation
lies between |
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the
spatial and Fourier domains. For images, the wavelet representation
differentiates |
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several
spatial orientations. The application of this representation to data
compression in |
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image
coding, texture discrimination and fractal analysis is discussed.
|
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Multiresolution
transient detection |
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Time-Frequency
and Time-Scale Analysis, 1994., Proceedings of the IEEE-SP |
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International
Symposium on , 1994 |
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Designs
and studies the performance of a multiresolution-based transient detector.
The |
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transients
the authors are interested in consist of wide-band, pulse-like, coherent |
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structures
in a turbulent flow. To take advantage of the fast pyramidal wavelet
algorithm, |
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an
important point when processing large amounts of experimental data, the
detector |
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makes
use of the discrete wavelet transform. The authors show how the lack of |
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time-invariance
drawback of the discrete transform can be efficiently overcome by using |
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relevant
analytic wavelets. They thus compare this detection technique with one
based on |
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a
continuous wavelet transform, as well as with other standard methods and
show that |
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wavelets
perform best when the transients are superimposed on a colored 1/f
background |
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noise.
This description is very close to that of turbulence and relevant also in
many other |
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A
fuzzy-logic-based threshold function for signal recovery using discrete
wavelet |
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Wenbo
Mei; Lik-Kwan Shark |
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Signal
Processing, 1996., 3rd International Conference on , Volume: 1 , 1996 |
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In
this paper, a novel threshold function based on fuzzy logic is proposed to
achieve good |
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signal
recovery performance in the presence of noise using the discrete wavelet |
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transform.
The proposed threshold is shown to provide an alternative and flexible |
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approach
to solve the problems associated with the conventional hard-threshold
approach. |
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Some
typical results, obtained from the computer simulations of recovering a
transient |
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signal
embedded in additive white Gaussian noise in different signal-to-noise
ratio settings, |
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are
presented to demonstrate the potential and the effectiveness of the
proposed |
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End
effect analysis of linear induction motor based on the wavelet transform |
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Mori,
Y.; Torii, S.; Ebihara, D. |
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Magnetics,
IEEE Transactions on , Volume: 35 Issue: 5 Part: 2 , Sept. 1999 |
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The
performance of LIM is degraded due to the influence of the end effects.
LIM is |
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analyzed
using the Fourier series expansion to throw light on this problem. However, |
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when
we want to obtain the high-accuracy in this technique, the number of times
for |
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calculation
is increased. In the case of the wavelet transform technique, as the
wavelet |
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coefficients
converge rapidly to zero, this technique has been applied to analyze the
end |
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effects
of LIM. In this paper, we investigated the method for determining mother |
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Some
notes on wavelet analysis of time-variant electrical networks |
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Circuits
and Systems, 2000. Proceedings of the 43rd IEEE Midwest Symposium on , |
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After
presenting a new approach for the analysis and the resolution of linear
time variant |
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circuits
base on wvletes functions the author are introducing some specific
consideration |
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relates
to matrix propoerties associated to such methodology. The simple recursive |
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algorithm
for the construction of the integral and convolution matrixes and the
topological |
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matrix
are evaluated more in depth in order to outcome the most interesting
features |
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proposal
for numerical optimizations are also given. And example including a three
phase |
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inverter
study using such technique is presented.
|
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A
unified wavelet-based approach to electrical machine modeling |
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Fedrigo,
S.; Gandelli, A.; Monti, A.; Ponci, F. |
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Electric
Machines and Drives Conference, 2000. IEMDC 2001. IEEE International ,
2001 |
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The
paper presents an original approach to electrical machine modeling based
on wavelet |
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transformation.
The main purpose of the approach is to give a more detailed description of |
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the
field in the airgap removing the hypothesis of sinusoidal field
distribution typical of a |
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traditional
space-phasor approach. As a result, a more detailed closed-form analysis
is |
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possible
including torque ripple evaluation.
|
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Condition
assessment of power transformer on-load tap-changers using wavelet |
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Pengju
Kang; Birtwhistle, D. |
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Power
Delivery, IEEE Transactions on , Volume: 16 Issue: 3 , July 2001 |
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The
operation of a power transformer on-load tap-changer (OLTC) produces a |
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well-defined
series of vibration bursts as its signature. Due to the harmonic and |
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nonstationary
nature of the transient vibration signal, traditional frequency and |
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time-frequency
techniques are on longer effective for characterization of this type of |
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vibration
signals, as the localized time domain features, such as delays between
bursts, the |
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number
of bursts, and the strengths of bursts, are essential for the condition
assessment |
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of
OLTC. A wavelet transform based technique is developed in this paper to
characterize |
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the
OLTC vibration signals. This technique gives a simplified format for
displaying and |
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representing
the essential features of the OLTC vibration signatures. Application
results |
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from a
selector type OLTC demonstrate that the features extracted in the wavelet |
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domain
can be utilized to provide reliable indications of the actual heath of an
OLTC.
|
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Genetic
algorithm wavelet design for signal classification |
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Jones,
E.; Runkle, P.; Dasgupta, N.; Couchman, L.; Carin, L. |
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Pattern
Analysis and Machine Intelligence, IEEE Transactions on , Volume: 23 Issue:
8 , |
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Biorthogonal
wavelets are applied to parse multiaspect transient scattering data in the |
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context
of signal classification. A language-based genetic algorithm is used to
design |
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wavelet
filters that enhance classification performance. The biorthogonal wavelets
are |
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implemented
via the lifting procedure and the optimization is carried out using a |
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classification-based
cost function. Example results are presented for target classification |
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using
measured scattering data. |
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