25,329 research outputs found
Blind Normalization of Speech From Different Channels
We show how to construct a channel-independent representation of speech that
has propagated through a noisy reverberant channel. This is done by blindly
rescaling the cepstral time series by a non-linear function, with the form of
this scale function being determined by previously encountered cepstra from
that channel. The rescaled form of the time series is an invariant property of
it in the following sense: it is unaffected if the time series is transformed
by any time-independent invertible distortion. Because a linear channel with
stationary noise and impulse response transforms cepstra in this way, the new
technique can be used to remove the channel dependence of a cepstral time
series. In experiments, the method achieved greater channel-independence than
cepstral mean normalization, and it was comparable to the combination of
cepstral mean normalization and spectral subtraction, despite the fact that no
measurements of channel noise or reverberations were required (unlike spectral
subtraction).Comment: 25 pages, 7 figure
Investigation of the Cape Rosier Zinc-Copper-Lead Mine, Hancock County, Maine
From the introduction: The Bureau of Mines has been investigating deposits of critical and essential minerals in the United Sates and Alaska since 1939. During the fall of 1942, the Bureau of Mines put down nine diamond-drill holes at the Cape Rosier zinc-copper-lead mine in Hancock County, Maine, that aggregated 2,883 feet of bore... This report describes the work done by the Bureau of Mines and presents the data obtained in the two periods of drilling.
Report of Investigations no. 4344 (R. I. 4344)
Three charged particles in the continuum. Astrophysical examples
We suggest a new adiabatic approach for description of three charged
particles in the continuum. This approach is based on the Coulomb-Fourier
transformation (CFT) of three body Hamiltonian, which allows to develop a
scheme, alternative to Born-Oppenheimer one.
The approach appears as an expansion of the kernels of corresponding integral
transformations in terms of small mass-ratio parameter. To be specific, the
results are presented for the system in the continuum. The wave function
of a such system is compared with that one which is used for estimation of the
rate for triple reaction which take place as a step of
-cycle in the center of the Sun. The problem of microscopic screening for
this particular reaction is discussed
Coulomb gap in the one-particle density of states in three-dimensional systems with localized electrons
The one-particle density of states (1P-DOS) in a system with localized
electron states vanishes at the Fermi level due to the Coulomb interaction
between electrons. Derivation of the Coulomb gap uses stability criteria of the
ground state. The simplest criterion is based on the excitonic interaction of
an electron and a hole and leads to a quadratic 1P-DOS in the three-dimensional
(3D) case. In 3D, higher stability criteria, including two or more electrons,
were predicted to exponentially deplete the 1P-DOS at energies close enough to
the Fermi level. In this paper we show that there is a range of intermediate
energies where this depletion is strongly compensated by the excitonic
interaction between single-particle excitations, so that the crossover from
quadratic to exponential behavior of the 1P-DOS is retarded. This is one of the
reasons why such exponential depletion was never seen in computer simulations.Comment: 6 pages, 1 figur
Application of Monte Carlo Algorithms to the Bayesian Analysis of the Cosmic Microwave Background
Power spectrum estimation and evaluation of associated errors in the presence
of incomplete sky coverage; non-homogeneous, correlated instrumental noise; and
foreground emission is a problem of central importance for the extraction of
cosmological information from the cosmic microwave background. We develop a
Monte Carlo approach for the maximum likelihood estimation of the power
spectrum. The method is based on an identity for the Bayesian posterior as a
marginalization over unknowns. Maximization of the posterior involves the
computation of expectation values as a sample average from maps of the cosmic
microwave background and foregrounds given some current estimate of the power
spectrum or cosmological model, and some assumed statistical characterization
of the foregrounds. Maps of the CMB are sampled by a linear transform of a
Gaussian white noise process, implemented numerically with conjugate gradient
descent. For time series data with N_{t} samples, and N pixels on the sphere,
the method has a computational expense $KO[N^{2} +- N_{t} +AFw-log N_{t}],
where K is a prefactor determined by the convergence rate of conjugate gradient
descent. Preconditioners for conjugate gradient descent are given for scans
close to great circle paths, and the method allows partial sky coverage for
these cases by numerically marginalizing over the unobserved, or removed,
region.Comment: submitted to Ap
QND and higher order effects for a nonlinear meter in an interferometric gravitational wave antenna
A new optical topology and signal readout strategy for a laser interferometer
gravitational wave detector were proposed recently by Braginsky and Khalili .
Their method is based on using a nonlinear medium inside a microwave oscillator
to detect the gravitational-wave-induced spatial shift of the interferometer's
standing optical wave. This paper proposes a quantum nondemolition (QND) scheme
that could be realistically used for such a readout device and discusses a
"fundamental" sensitivity limit imposed by a higher order optical effect.Comment: LaTex, 17 pages, 3 figure
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