6,654 research outputs found

    Language Transfer of Audio Word2Vec: Learning Audio Segment Representations without Target Language Data

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    Audio Word2Vec offers vector representations of fixed dimensionality for variable-length audio segments using Sequence-to-sequence Autoencoder (SA). These vector representations are shown to describe the sequential phonetic structures of the audio segments to a good degree, with real world applications such as query-by-example Spoken Term Detection (STD). This paper examines the capability of language transfer of Audio Word2Vec. We train SA from one language (source language) and use it to extract the vector representation of the audio segments of another language (target language). We found that SA can still catch phonetic structure from the audio segments of the target language if the source and target languages are similar. In query-by-example STD, we obtain the vector representations from the SA learned from a large amount of source language data, and found them surpass the representations from naive encoder and SA directly learned from a small amount of target language data. The result shows that it is possible to learn Audio Word2Vec model from high-resource languages and use it on low-resource languages. This further expands the usability of Audio Word2Vec.Comment: arXiv admin note: text overlap with arXiv:1603.0098

    String Theory and Turbulence

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    We propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. This string theory of turbulence should be understood in light of the AdS/CFT dictionary. Our argument is crucially based on the use of Migdal's loop variables and the self-consistent solutions of Migdal's loop equations for turbulence. In particular, there is an area law for turbulence in 2+1 dimensions related to the Kraichnan scaling.Comment: LaTeX; 15 pages, two figures; v.2: slight changes to text, footnotes and references adde

    Quantum Gravity and Turbulence

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    We apply recent advances in quantum gravity to the problem of turbulence. Adopting the AdS/CFT approach we propose a string theory of turbulence that explains the Kolmogorov scaling in 3+1 dimensions and the Kraichnan and Kolmogorov scalings in 2+1 dimensions. In the gravitational context, turbulence is intimately related to the properties of spacetime, or quantum, foam.Comment: 8 pages, LaTeX; Honorable Mention in the 2010 Gravity Research Foundation Essay Contes

    Ignition and Front Propagation in Polymer Electrolyte Membrane Fuel Cells

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    Water produced in a Polymer Electrolyte Membrane (PEM) fuel cell enhances membrane proton conductivity; this positive feedback loop can lead to current ignition. Using a segmented anode fuel cell we study the effect of gas phase convection and membrane diffusion of water on the spatiotemporal nonlinear dynamics - localized ignition and front propagation - in the cell. Co-current gas flow causes ignition at the cell outlet, and membrane diffusion causes the front to slowly propagate to the inlet; counter-current flow causes ignition in the interior of the cell, with the fronts subsequently spreading towards both inlets. These instabilities critically affect fuel cell performance

    A Comparative Study of Dark Energy Constraints from Current Observational Data

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    We examine how dark energy constraints from current observational data depend on the analysis methods used: the analysis of Type Ia supernovae (SNe Ia), and that of galaxy clustering data. We generalize the flux-averaging analysis method of SNe Ia to allow correlated errors of SNe Ia, in order to reduce the systematic bias due to weak lensing of SNe Ia. We find that flux-averaging leads to larger errors on dark energy and cosmological parameters if only SN Ia data are used. When SN Ia data (the latest compilation by the SNLS team) are combined with WMAP 7 year results (in terms of our Gaussian fits to the probability distributions of the CMB shift parameters), the latest Hubble constant (H_0) measurement using the Hubble Space Telescope (HST), and gamma ray burst (GRB) data, flux-averaging of SNe Ia increases the concordance with other data, and leads to significantly tighter constraints on the dark energy density at z=1, and the cosmic curvature \Omega_k. The galaxy clustering measurements of H(z=0.35)r_s(z_d) and r_s(z_d)/D_A(z=0.35) (where H(z) is the Hubble parameter, D_A(z) is the angular diameter distance, and r_s(z_d) is the sound horizon at the drag epoch) by Chuang & Wang (2011) are consistent with SN Ia data, given the same pirors (CMB+H_0+GRB), and lead to significantly improved dark energy constraints when combined. Current data are fully consistent with a cosmological constant and a flat universe.Comment: 11 pages, 9 figures. Slightly revised version, to appear in PRD. Supernova flux-averaging code available at http://www.nhn.ou.edu/~wang/SNcode

    Charmed Baryon Weak Decays with SU(3) Flavor Symmetry

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    We study the semileptonic and non-leptonic charmed baryon decays with SU(3)SU(3) flavor symmetry, where the charmed baryons can be Bc=(Ξc0,Ξc+,Ξ›c+){\bf B}_{c}=(\Xi_c^0,\Xi_c^+,\Lambda_c^+), Bcβ€²=(Ξ£c(++,+,0),Ξcβ€²(+,0),Ξ©c0){\bf B}'_{c}=(\Sigma_c^{(++,+,0)},\Xi_{c}^{\prime(+,0)},\Omega_c^0), Bcc=(Ξcc++,Ξcc+,Ξ©cc+){\bf B}_{cc}=(\Xi_{cc}^{++},\Xi_{cc}^+,\Omega_{cc}^+), or Bccc=Ξ©ccc++{\bf B}_{ccc}=\Omega^{++}_{ccc}. With Bn(β€²){\bf B}_n^{(\prime)} denoted as the baryon octet (decuplet), we find that the Bcβ†’Bnβ€²β„“+Ξ½β„“{\bf B}_{c}\to {\bf B}'_n\ell^+\nu_\ell decays are forbidden, while the Ξ©c0β†’Ξ©βˆ’β„“+Ξ½β„“\Omega_c^0\to \Omega^-\ell^+\nu_\ell, Ξ©cc+β†’Ξ©c0β„“+Ξ½β„“\Omega_{cc}^+\to\Omega_c^0\ell^+\nu_\ell, and Ξ©ccc++β†’Ξ©cc+β„“+Ξ½β„“\Omega_{ccc}^{++}\to \Omega_{cc}^+\ell^+\nu_\ell decays are the only existing Cabibbo-allowed modes for Bcβ€²β†’Bnβ€²β„“+Ξ½β„“{\bf B}'_{c}\to {\bf B}'_n\ell^+\nu_\ell, Bccβ†’Bcβ€²β„“+Ξ½β„“{\bf B}_{cc}\to {\bf B}'_c\ell^+\nu_\ell, and Bcccβ†’Bcc(β€²)β„“+Ξ½β„“{\bf B}_{ccc}\to {\bf B}_{cc}^{(\prime)}\ell^+\nu_\ell, respectively. We predict the rarely studied Bcβ†’Bn(β€²)M{\bf B}_{c}\to {\bf B}_n^{(\prime)}M decays, such as B(Ξc0β†’Ξ›0KΛ‰0,β€‰Ξžc+β†’Ξž0Ο€+)=(8.3Β±0.9,8.0Β±4.1)Γ—10βˆ’3{\cal B}(\Xi_c^0\to\Lambda^0\bar K^0,\,\Xi_c^+\to\Xi^0\pi^+)=(8.3\pm 0.9,8.0\pm 4.1)\times 10^{-3} and B(Ξ›c+β†’Ξ”++Ο€βˆ’,β€‰Ξžc0β†’Ξ©βˆ’K+)=(5.5Β±1.3,4.8Β±0.5)Γ—10βˆ’3{\cal B}(\Lambda_c^+\to \Delta^{++}\pi^-,\,\Xi_c^0\to\Omega^- K^+)=(5.5\pm 1.3,4.8\pm 0.5)\times 10^{-3}. For the observation, the doubly and triply charmed baryon decays of Ξ©cc+β†’Ξžc+KΛ‰0\Omega_{cc}^{+}\to \Xi_c^+\bar K^0, Ξcc++β†’(Ξc+Ο€+\Xi_{cc}^{++}\to (\Xi_c^+\pi^+, Ξ£c++KΛ‰0)\Sigma_c^{++}\bar K^0), and Ξ©ccc++β†’(Ξcc++KΛ‰0,Ξ©cc+Ο€+,Ξc+D+)\Omega_{ccc}^{++}\to (\Xi_{cc}^{++}\bar K^0,\Omega_{cc}^+\pi^+,\Xi_c^+ D^+) are the favored Cabibbo-allowed decays, which are accessible to the BESIII and LHCb experiments.Comment: 29 pages, no figure, a typo in the table correcte

    Coordinated Multicasting with Opportunistic User Selection in Multicell Wireless Systems

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    Physical layer multicasting with opportunistic user selection (OUS) is examined for multicell multi-antenna wireless systems. By adopting a two-layer encoding scheme, a rate-adaptive channel code is applied in each fading block to enable successful decoding by a chosen subset of users (which varies over different blocks) and an application layer erasure code is employed across multiple blocks to ensure that every user is able to recover the message after decoding successfully in a sufficient number of blocks. The transmit signal and code-rate in each block determine opportunistically the subset of users that are able to successfully decode and can be chosen to maximize the long-term multicast efficiency. The employment of OUS not only helps avoid rate-limitations caused by the user with the worst channel, but also helps coordinate interference among different cells and multicast groups. In this work, efficient algorithms are proposed for the design of the transmit covariance matrices, the physical layer code-rates, and the target user subsets in each block. In the single group scenario, the system parameters are determined by maximizing the group-rate, defined as the physical layer code-rate times the fraction of users that can successfully decode in each block. In the multi-group scenario, the system parameters are determined by considering a group-rate balancing optimization problem, which is solved by a successive convex approximation (SCA) approach. To further reduce the feedback overhead, we also consider the case where only part of the users feed back their channel vectors in each block and propose a design based on the balancing of the expected group-rates. In addition to SCA, a sample average approximation technique is also introduced to handle the probabilistic terms arising in this problem. The effectiveness of the proposed schemes is demonstrated by computer simulations.Comment: Accepted by IEEE Transactions on Signal Processin
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