17,650 research outputs found
Speaker verification using sequence discriminant support vector machines
This paper presents a text-independent speaker verification system using support vector machines (SVMs) with score-space kernels. Score-space kernels generalize Fisher kernels and are based on underlying generative models such as Gaussian mixture models (GMMs). This approach provides direct discrimination between whole sequences, in contrast with the frame-level approaches at the heart of most current systems. The resultant SVMs have a very high dimensionality since it is related to the number of parameters in the underlying generative model. To address problems that arise in the resultant optimization we introduce a technique called spherical normalization that preconditions the Hessian matrix. We have performed speaker verification experiments using the PolyVar database. The SVM system presented here reduces the relative error rates by 34% compared to a GMM likelihood ratio system
Speech and crosstalk detection in multichannel audio
The analysis of scenarios in which a number of microphones record the activity of speakers, such as in a round-table meeting, presents a number of computational challenges. For example, if each participant wears a microphone, speech from both the microphone's wearer (local speech) and from other participants (crosstalk) is received. The recorded audio can be broadly classified in four ways: local speech, crosstalk plus local speech, crosstalk alone and silence. We describe two experiments related to the automatic classification of audio into these four classes. The first experiment attempted to optimize a set of acoustic features for use with a Gaussian mixture model (GMM) classifier. A large set of potential acoustic features were considered, some of which have been employed in previous studies. The best-performing features were found to be kurtosis, "fundamentalness," and cross-correlation metrics. The second experiment used these features to train an ergodic hidden Markov model classifier. Tests performed on a large corpus of recorded meetings show classification accuracies of up to 96%, and automatic speech recognition performance close to that obtained using ground truth segmentation
The hybrid returns-to-scale model and its extension by production trade-offs: an application to the efficiency assessment of public universities in Malaysia
Most applications of data envelopment analysis (DEA) employ standard constant
or variable returns-to-scale models. In this paper we suggest that these models may sometimes
underutilize our knowledge of the underlying production process. For example, in the
context of higher education considered in the reported application, individual universities
often maintain a certain student-to-staff ratio which points that there should be an approximately
proportional relationship between students and staff, at least in the medium to long
run.Adifferent example is an observation that the teaching of postgraduate students generally
requires more resources than the teaching of the same number of undergraduate students. In
order to incorporate such information in a DEA model, we propose a novel approach that
combines the recently developed hybrid returns-to-scale DEA model with the use of production
trade-offs. The suggested approach leads to a better-informed model of production
technology than the conventional DEA models. We illustrate this methodology by an application
to Malaysian public universities. This approach results in a tangibly better efficiency
discrimination than would be possible with the standard DEA models
Cosmic Coincidence and Asymmetric Dark Matter in a Stueckelberg Extension
We discuss the possibility of cogenesis generating the ratio of baryon
asymmetry to dark matter in a Stueckelberg U(1) extension of the standard model
and of the minimal supersymmetric standard model. For the U(1) we choose
which is anomaly free and can be gauged. The dark matter
candidate arising from this extension is a singlet of the standard model gauge
group but is charged under . Solutions to the Boltzmann
equations for relics in the presence of asymmetric dark matter are discussed.
It is shown that the ratio of the baryon asymmetry to dark matter consistent
with the current WMAP data, i.e., the cosmic coincidence, can be successfully
explained in this model with the depletion of the symmetric component of dark
matter from resonant annihilation via the Stueckelberg gauge boson. For the
extended MSSM model it is shown that one has a two component dark matter
picture with asymmetric dark matter being the dominant component and the
neutralino being the subdominant component (i.e., with relic density a small
fraction of the WMAP cold dark matter value). Remarkably, the subdominant
component can be detected in direct detection experiments such as SuperCDMS and
XENON-100. Further, it is shown that the class of Stueckelberg models with a
gauged will produce a dramatic signature at a muon collider
with the showing a detectable
resonance while is devoid of this
resonance. Asymmetric dark matter arising from a Stueckelberg
extension is also briefly discussed. Finally, in the models we propose the
asymmetric dark matter does not oscillate and there is no danger of it being
washed out from oscillations.Comment: 36 pages, 7 figure
Simulation of transition dynamics to high confinement in fusion plasmas
The transition dynamics from the low (L) to the high (H) confinement mode in
magnetically confined plasmas is investigated using a first-principles
four-field fluid model. Numerical results are in close agreement with
measurements from the Experimental Advanced Superconducting Tokamak - EAST.
Particularly, the slow transition with an intermediate dithering phase is well
reproduced by the numerical solutions. Additionally, the model reproduces the
experimentally determined L-H transition power threshold scaling that the ion
power threshold increases with increasing particle density. The results hold
promise for developing predictive models of the transition, essential for
understanding and optimizing future fusion power reactors
Evolution of AQL X-1 During the Rising Phase of its 1998 Outburst
We present results from 16 snapshots of Aql X-1 with RXTE during the rising
phase of its recent outburst. The observations were carried out at a typical
rate of once or twice per day. The source shows interesting spectral evolution
during this period. Phenomenologically, it bears remarkable similarities to
``atoll'' sources. Shortly after the onset of the outburst, the source is seen
to be in an ``island'' state, but with little X-ray variability. It then
appears to have made a rapid spectral transition (on a time scale less than
half a day) to another ``island'' state, where it evolves slightly and stays
for 4 days. In this state, the observed X-ray flux becomes increasingly
variable as the source brightens. Quasi-period oscillation (QPO) in the X-ray
intensity is detected in the frequency range 670--870 Hz. The QPO frequency
increases with the X-ray flux while its fractional rms decreases. The QPO
becomes undetectable following a transition to a ``banana'' state, where the
source continues its evolution by moving up and down the ``banana'' branch in
the color-color diagram as the flux (presumably, the mass accretion rate)
fluctuates around the peak of the outburst. Throughout the entire period, the
power density spectrum is dominated by very-low frequency noises. Little power
can be seen above ~1 Hz, which is different from typical ``atoll'' sources. In
the ``banana'' state, the overall X-ray variability remains low (with
fractional rms ~3--4%) but roughly constant. The observed X-ray spectrum is
soft with few photons from above 25 keV, implying the thermal origin of
the emission. The evolution of both spectral and temporal X-ray properties is
discussed in the context of disk-instability models.Comment: 13 pages, including one table and five figures. To appear in ApJ
Letters (July 20
Dust ion-acoustic shocks in quantum dusty pair-ion plasmas
The formation of dust ion-acoustic shocks (DIASs) in a four-component quantum
plasma whose constituents are electrons, both positive and negative ions and
immobile charged dust grains, is studied. The effects of both the dissipation
due to kinematic viscosity and the dispersion caused by the charge separation
as well as the quantum tunneling due to the Bohm potential are taken into
account. The propagation of small but finite amplitude dust ion-acoustic waves
(DIAWs) is governed by the Korteweg-de Vries-Burger (KdVB) equation which
exhibits both oscillatory and monotonic shocks depending not only on the
viscosity parameters, but also on the quantum parameter H (the ratio of the
electron plasmon to the electron Fermi energy) and the positive to negative ion
density ratio. Large amplitude stationary shocks are recovered for a Mach
number exceeding its critical value. Unlike the small amplitude shocks, quite a
smaller value of the viscosity parameter, H and the density ratio may lead to
the large amplitude monotonic shock strucutres. The results could be of
importance in astrophysical and laser produced plasmas.Comment: 15 pages, 5 figure
Pelaksanaan Rencana Induk Pembangunan Kepariwisataan Daerah Kabupaten Kampar Tahun 2010-2015
With magnitude potential owned tourism by Kampar, then Local Government District. Kampar do an important step by organizing tourism potentials owned by Kampar Regency. The main steps that should be carried out within the framework of the development of the tourism sector Kampar District is preparing a Plan Regional Tourism Development Master Kampar, then expected able for improve development tourism in Kampar. By because that aim research this is for knowing implementation Plan Regional Tourism Development Master Kampar.The method used in writing research this is approach qualitatively. Informants of this study were chosen purposively based on characteristics or specific characteristics based on research needs. That is 7 people.As for results research RIPKD implementation Kab. Kampar are: 1) lack of work same government with developers tourism, 2) has not existence promotion done government constrained because inadequate budget and source power human, 3) formation group conscious tours this not yet accomplished. While obstacles is 1) Situation people are still not yet can for receive climate tourism whole, 2) Presence in part object still travel located in in Forest custom and Forest protection, 3) Presence object Scattered travel make hard for formed ka-bag ntong destination travel.With existence barriers, then efforts that could do are: 1) Increasing Cooperation. 2) Development Investment, 3) Development Infrastructure, 3) Formation Destinations Featured, 4) Increased Promotion to Regional Affairs / Interior., 5) Formation Institutional, 6) Participation Society, 7) Awareness SocietyWor
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