Wavelet Analysis

Galactic globular clusters are ancient building blocks of our Galaxy. They represent a very interesting family of stellar systems in which some fundamental dynamical processes have been taking place for more than 10 Gyr, but on time scales shorter than the age of the universe. In contrast with galaxies, these star clusters represent unique laboratories for learning about two-body relaxation, mass segregation from equipartition of energy, stellar collisions, stellar mergers, core collapse, and tidal disruption. This review briefly summarizes some of the tremendous developments that have taken place during the last two decades. It ends with some recent results on tidal tails around galactic globular clusters and on a very massive globular cluster in M31. IntroductionThere are about 150 globulars orbiting in the halo of our Galaxy. They look like huge swarms of stars, characterized by symmetry and apparent smoothness. Fig. 1 below displays an image of NGC 5139 ≡ ω Centauri, the brightest and most massive galactic globular cluster. This 40 ′ by 40 ′ image from the Digital Sky Survey does not reach, in spite of its rather large angular size, the outer parts of the cluster. With its tidal radius of about 40-50 ′ , the apparent diameter of ω Centauri on the plane of the sky is significantly larger than the apparent 30 ′ diameter of the full moon. Globular clusters are old stellar systems, made of one single generation of stars. Although still somewhat uncertain, their individual ages range between about 10 and 15 Gyr, with possible significant differences, up to a few gigayears, from one cluster to the other. Other properties of globular clusters exhibit significant variations: e.g., their integrated absolute magnitudes range from M int V = -1.7 to -10.1 mag; their total masses from M tot = 10 3 to 5 × 10 6 M ⊙ ; their galactocentric distances from 2 to 120 kpc. 2A few dynamical time scalesThe dynamics of any stellar system may be characterized by the following three dynamical time scales: (i) the crossing time t cr , which is the time needed by a star to move across the system; (ii) the relaxation time t rlx , which is the meylanreview:

show abstract

“…Slezak et al 1994;Resnikoff & Wells 1998). Any observational signal includes also some noise, which has a short scale length.…”

Section: Wavelet Analysismentioning

confidence: 99%

Internal dynamics of globular clusters

Meylan

Heggie

1997

Astronomy and Astrophysics Review

425

394

View full text Add to dashboard Cite

show abstract

“…For a clear reading on this subject a standard quotation is [1]. Reference [2] is an updated book where other interesting aspects of wavelets are discussed. What cannot be found in many textbooks since is still to be understood, is the relevance of wavelets in quantum mechanics: at this moment, in our knowledge, very few are the applications proposed in this field, [3,4,5,6,7] and [8] among the others.…”

Section: Introductionmentioning

confidence: 99%

Multi-resolution analysis and fractional quantum Hall effect: An equivalence result

Багарелло

2001

Journal of Mathematical Physics

View full text Add to dashboard Cite

In this paper we prove that any multi-resolution analysis of L 2 (R R) produces, for some values of the filling factor, a single-electron wave function of the lowest Landau level (LLL) which, together with its (magnetic) translated, gives rise to an orthonormal set in the LLL. We also give the inverse construction. Moreover, we extend this procedure to the higher Landau levels and we discuss the analogies and the differences between this procedure and the one previously proposed by J.-P. Antoine and the author.

show abstract

“…Similarly, DL represents the output of the filtering operations 000...1 in which the total number of 0 is L-1. The impulse response of 000...1 converges asymptotically to the mother wavelet and the impulse response of 000...0 converges to the scaling function in the wavelet transform [9,7,11] …”

Section: Figure 3 Discrete Wavelet Transformationmentioning

confidence: 99%

Incipient Fault Detection of the Inverter Fed Induction Motor Drive

Ramana¹,

Baskar²

2017

IJPEDS

View full text Add to dashboard Cite

Inverter fed Induction motor drives are deployed across a variety of industrial and commercial applications. Although the drives in the question are well known for their reliable operation in any type of environment, it becomes an important daunting critical task to have them in continuous operation as per the applications" requirement. Identifying the faulty behavior of power electronic circuits which could lead to catastrophic failures is an attractive proposition. The cost associated with building systems devoted for monitoring and diagnosis is high, however such cost could be justified for the safety-critical systems. Commonly practiced methods for improving the reliability of the power electronic systems are: designing the power circuit conservatively or having parallel redundant operation of components or circuits and clearly these two methods are expensive. An alternative to redundancy is fault tolerant control, which involves drive control algorithm, that in the event of fault occurrence, allows the drive to run in a degraded mode. Such algorithms involve on-line processing of the signals and this requires Digital Signal Processing of the signals. This paper presents the FFT and Wavelet transform techniques for on-line monitoring and analyzing the signals such as stator currents.

show abstract

Wavelet Analysis

Cited by 171 publications

References 0 publications

Internal dynamics of globular clusters

Internal dynamics of globular clusters

Multi-resolution analysis and fractional quantum Hall effect: An equivalence result

Incipient Fault Detection of the Inverter Fed Induction Motor Drive

Contact Info

Product

Resources

About