3,587 research outputs found
Gravitational resonances on -brane
In this paper, we investigate various -brane models and compare their
gravitational resonance structures with the corresponding general relativity
(GR)-branes. {Starting from some known GR-brane solutions}, we derive thick
-brane solutions such that the metric, scalar field, and scalar potential
coincide with those of the corresponding GR-branes. {We find that for branes
generated by a single or several canonical scalar fields, there is no obvious
distinction between the GR-branes and corresponding -branes in terms of
gravitational resonance structure.} Then we discuss the branes generated by
K-fields. In this case, there could exist huge differences between GR-branes
and -branes.Comment: 17 pages, 14 figures, published versio
Full linear perturbations and localization of gravity on brane
We study the thick brane world system constructed in the recently proposed
theories of gravity, with the Ricci scalar and the trace of
the energy-momentum tensor. We try to get the analytic background solutions and
discuss the full linear perturbations, especially the scalar perturbations. We
compare how the brane world model is modified with that of general relativity
coupled to a canonical scalar field. It is found that some more interesting
background solutions are allowed, and only the scalar perturbation mode is
modified. There is no tachyon state exists in this model and only the massless
tensor mode can be localized on the brane, which recovers the effective
four-dimensional gravity. These conclusions hold provided that two constraints
on the original formalism of the action are satisfied.Comment: v3: 8 pages, 2 figures, improved version with minor corrections,
accepted by EPJ
Robust Sound Event Classification using Deep Neural Networks
The automatic recognition of sound events by computers is an important aspect of emerging applications such as automated surveillance, machine hearing and auditory scene understanding. Recent advances in machine learning, as well as in computational models of the human auditory system, have contributed to advances in this increasingly popular research field. Robust sound event classification, the ability to recognise sounds under real-world noisy conditions, is an especially challenging task. Classification methods translated from the speech recognition domain, using features such as mel-frequency cepstral coefficients, have been shown to perform reasonably well for the sound event classification task, although spectrogram-based or auditory image analysis techniques reportedly achieve superior performance in noise.
This paper outlines a sound event classification framework that compares auditory image front end features with spectrogram image-based front end features, using support vector machine and deep neural network classifiers. Performance is evaluated on a standard robust classification task in different levels of corrupting noise, and with several system enhancements, and shown to compare very well with current state-of-the-art classification techniques
Approximation algorithms for -submodular maximization subject to a knapsack constraint
In this paper, we study the problem of maximizing -submodular functions
subject to a knapsack constraint. For monotone objective functions, we present
a greedy approximation algorithm. For the
non-monotone case, we are the first to consider the knapsack problem and
provide a greedy-type combinatorial algorithm with approximation ratio
Does Hawking effect always degrade fidelity of quantum teleportation in Schwarzschild spacetime?
Previous studies have shown that the Hawking effect always destroys quantum
correlations and the fidelity of quantum teleportation in the Schwarzschild
black hole. Here, we investigate the fidelity of quantum teleportation of Dirac
fields between users in Schwarzschild spacetime. We find that, with the
increase of the Hawking temperature, the fidelity of quantum teleportation can
monotonically increase, monotonically decrease, or non-monotonically increase,
depending on the choice of the initial state, which means that the Hawking
effect can create net fidelity of quantum teleportation. This striking result
banishes the extended belief that the Hawking effect of the black hole can only
destroy the fidelity of quantum teleportation. We also find that quantum
steering cannot fully guarantee the fidelity of quantum teleportation in
Schwarzschild spacetime. This new unexpected source may provide a new idea for
the experimental evidence of the Hawking effect.Comment: 21 pages, 3 figures, accepted for publication in JHE
Exact Numerical Solution of the BCS Pairing Problem
We propose a new simulation computational method to solve the reduced BCS
Hamiltonian based on spin analogy and submatrix diagonalization. Then we
further apply this method to solve superconducting energy gap and the results
are well consistent with those obtained by Bogoliubov transformation method.
The exponential problem of 2^{N}-dimension matrix is reduced to the polynomial
problem of N-dimension matrix. It is essential to validate this method on a
real quantumComment: 7 pages, 3 figure
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