19,471 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
Analysis of uniform binary subdivision schemes for curve design
The paper analyses the convergence of sequences of control polygons produced by a binary subdivision scheme of the form
.0,1,2,...kz,ikj,ifjbm0j1k12ifjam0j1k2if=∈+Σ==++Σ==+
The convergence of the control polygons to a Cu curve is analysed in terms
of the convergence to zero of a derived scheme for the differences - . The analysis of the smoothness of the limit curve is reduced to kif
the convergence analysis of "differentiated" schemes which correspond to
divided differences of {/i ∈Z} with respect to the diadic parameteriz- kif
ation = i/2kitk . The inverse process of "integration" provides schemes
with limit curves having additional orders of smoothness
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Uniform subdivision algorithms for curves and surfaces
A convergence analysis for studying the continuity and differentiability of limit curves generated by uniform subdivision algorithms is presented. The analysis is based on the study of corresponding difference and divided difference algorithms. The alternative process of "integrating" the algorithms is considered. A specific example of a 4-point interpolatory curve algorithm is described and its generalization to a surface algorithm defined over a subdivision of a regular triangular partition is illustrated
The bergman kernel method for the numerical conformal mapping of simply connected domains
A numerical method for the conformal mapping of simply-connected domains onto the unit disc is considered. The method is based on the use of the Bergman kernel function of the domain. It is shown that, for a successful application, the basis of the series representation of the kernel must include terms that reflect the main singular behaviour of the kernel in the complement of the domain
Resonant enhanced multiphoton ionization studies of atomic oxygen
In resonant enhanced multiphoton ionization (REMPI), an atom absorbs several photons making a transition to a resonant intermediate state and subsequently ionizing out of it. With currently available tunable narrow-band lasers, the extreme sensitivity of REMPI to the specific arrangement of levels can be used to selectively probe minute amounts of a single species (atom) in a host of background material. Determination of the number density of atoms from the observed REMPI signal requires a knowledge of the multiphoton ionization cross sections. The REMPI of atomic oxygen was investigated through various excitation schemes that are feasible with available light sources. Using quantum defect theory (QDT) to estimate the various atomic parameters, the REMPI dynamics in atomic oxygen were studied incorporating the effects of saturation and a.c. Stark shifts. Results are presented for REMPI probabilities for excitation through various 2p(3) (4S sup o) np(3)P and 2p(3) (4S sup o) nf(3)F levels
Generalized Maxwell-Juttner distribution for rotating spinning particle gas
We consider a statistical mechanics and thermodynamics of a rotating ideal
gas of classical relativistic particles with nonzero mass and spin. Applying
the Gibbs theory of canonical ensembles for a system rotating with constant
angular velocity, we obtain the one-particle distribution function by
positions, momenta, and spin variables. By computing the partition function, we
obtain various thermodynamic quantities of slowly rotating gas. Both the
statistical and thermodynamic approaches demonstrate the polarization of
spinning degree of freedom, with the majority of spins being directed along the
angular velocity vector. This confirms the presence of chiral effects in the
system.Comment: 27 pages, 3 figure
Accelerated Detectors and Temperature in (Anti) de Sitter Spaces
We show, in complete accord with the usual Rindler picture, that detectors
with constant acceleration in de Sitter (dS) and Anti de Sitter (AdS)
spaces with cosmological constants measure temperatures , the detector "5-acceleration" in the
embedding flat 5-space. For dS, this recovers a known result; in AdS, where
is negative, the temperature is well defined down to the critical
value , again in accord with the underlying kinematics. The existence
of a thermal spectrum is also demonstrated for a variety of candidate wave
functions in AdS backgrounds.Comment: Latex +2 Fi
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