152,491 research outputs found
High-resolution spectral analysis
Analyzer extends the range and resolution of a digital spectrum analyzer without placing stringent stability requirements on the sampling rate. It compares an unknown signal with a stable frequency standard
Spectral Analysis Program (SAP)
Program eliminates or reduces time-consuming aspects of computation of power spectrum for high-frequency communication system. This program was written in FORTRAN IV for UNIVAC 1230 or 1108 computer
Spectral Analysis of Percolation Hamiltonians
We study the family of Hamiltonians which corresponds to the adjacency
operators on a percolation graph. We characterise the set of energies which are
almost surely eigenvalues with finitely supported eigenfunctions. This set of
energies is a dense subset of the algebraic integers. The integrated density of
states has discontinuities precisely at this set of energies. We show that the
convergence of the integrated densities of states of finite box Hamiltonians to
the one on the whole space holds even at the points of discontinuity. For this
we use an equicontinuity-from-the-right argument. The same statements hold for
the restriction of the Hamiltonian to the infinite cluster. In this case we
prove that the integrated density of states can be constructed using local data
only. Finally we study some mixed Anderson-Quantum percolation models and
establish results in the spirit of Wegner, and Delyon and Souillard.Comment: 19 pages, LaTeX 2e. See also preprint 04-326 on mp_arc. To appear in
a slightly different version in "Mathematische Annalen", see the DO
Spectral analysis for nonstationary audio
A new approach for the analysis of nonstationary signals is proposed, with a
focus on audio applications. Following earlier contributions, nonstationarity
is modeled via stationarity-breaking operators acting on Gaussian stationary
random signals. The focus is on time warping and amplitude modulation, and an
approximate maximum-likelihood approach based on suitable approximations in the
wavelet transform domain is developed. This paper provides theoretical analysis
of the approximations, and introduces JEFAS, a corresponding estimation
algorithm. The latter is tested and validated on synthetic as well as real
audio signal.Comment: IEEE/ACM Transactions on Audio, Speech and Language Processing,
Institute of Electrical and Electronics Engineers, In pres
OSSE spectral analysis techniques
Analysis of the spectra from the Oriented Scintillation Spectrometer Experiment (OSSE) is complicated because of the typically low signal to noise (approx. 0.1 percent) and the large background variability. The OSSE instrument was designed to address these difficulties by periodically offset-pointing the detectors from the source to perform background measurements. These background measurements are used to estimate the background during each of the source observations. The resulting background-subtracted spectra can then be accumulated and fitted for spectral lines and/or continua. Data selection based on various environmental parameters can be performed at various stages during the analysis procedure. In order to achieve the instrument's statistical sensitivity, however, it will be necessary for investigators to develop a detailed understanding of the instrument operation, data collection, and the background spectrum and its variability. A brief description of the major steps in the OSSE spectral analysis process is described, including a discussion of the OSSE background spectrum and examples of several observational strategies
Spectral Analysis for Matrix Hamiltonian Operators
In this work, we study the spectral properties of matrix Hamiltonians
generated by linearizing the nonlinear Schr\"odinger equation about soliton
solutions. By a numerically assisted proof, we show that there are no embedded
eigenvalues for the three dimensional cubic equation. Though we focus on a
proof of the 3d cubic problem, this work presents a new algorithm for verifying
certain spectral properties needed to study soliton stability. Source code for
verification of our comptuations, and for further experimentation, are
available at http://www.math.toronto.edu/simpson/files/spec_prop_code.tgz.Comment: 57 pages, 22 figures, typos fixe
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