15,608 research outputs found
Dimensional Regularization and Dimensional Reduction in the Light Cone
We calculate all the 2 to 2 scattering process in Yang-Mills theory in the
Light Cone gauge, with the dimensional regulator as the UV regulator. The IR is
regulated with a cutoff in . It supplements our earlier work, where a
Lorentz non-covariant regulator was used and the final results bear some
problems in gauge fixing. Supersymmetry relations among various amplitudes are
checked using the light cone superfields.Comment: current version accepted by PR
On fast radial propagation of parametrically excited geodesic acoustic mode
The spatial and temporal evolution of parametrically excited geodesic
acoustic mode (GAM) initial pulse is investigated both analytically and
numerically. Our results show that the nonlinearly excited GAM propagates at a
group velocity which is, typically, much larger than that due to finite ion
Larmor radius as predicted by the linear theory. The nonlinear dispersion
relation of GAM driven by a finite amplitude drift wave pump is also derived,
showing a nonlinear frequency increment of GAM. Further implications of these
findings for interpreting experimental observations are also discussed
Dynamical properties of a trapped dipolar Fermi gas at finite temperature
We investigate the dynamical properties of a trapped finite-temperature
normal Fermi gas with dipole-dipole interaction. For the free expansion
dynamics, we show that the expanded gas always becomes stretched along the
direction of the dipole moment. In addition, we present the temperature and
interaction dependences of the asymptotical aspect ratio. We further study the
collapse dynamics of the system by suddenly increasing the dipolar interaction
strength. We show that, in contrast to the anisotropic collapse of a dipolar
Bose-Einstein condensate, a dipolar Fermi gas always collapses isotropically
when the system becomes globally unstable. We also explore the interaction and
temperature dependences for the frequencies of the low-lying collective
excitations.Comment: 11 pages, 7 figure
Effects of energetic particles on zonal flow generation by toroidal Alfven eigenmode
Generation of zonal ow (ZF) by energetic particle (EP) driven toroidal Alfven
eigenmode (TAE) is investigated using nonlinear gyrokinetic theory. It is found
that, nonlinear resonant EP contri- bution dominates over the usual Reynolds
and Maxwell stresses due to thermal plasma nonlinear response. ZF can be forced
driven in the linear growth stage of TAE, with the growth rate being twice the
TAE growth rate. The ZF generation mechanism is shown to be related to
polarization induced by resonant EP nonlinearity. The generated ZF has both the
usual meso-scale and micro- scale radial structures. Possible consequences of
this forced driven ZF on the nonlinear dynamics of TAE are also discussed.Comment: To be submitted to Physics of Plasma
A composite objective measure on subjective evaluation of speech enhancement algorithms
© 2018 Elsevier Ltd Speech enhancement algorithms is to improve speech quality, naturalness and intelligibility by eliminating the background noise and improving signal to noise ratio. There are several objective measures predicting the quality of noisy speech enhanced by noise suppression algorithms, and different objective measures capture different characteristics of the degraded signal. In this paper, the multiple linear regression analysis is used to obtain a composite measure which has high correlation with subjective tests, and the performance of several speech enhancement algorithms under car noise conditions is compared. The uncertainty of the results of the proposed measures on different speech enhancement algorithms is analyzed, and the reliability of the results is discussed
A Deep Relevance Matching Model for Ad-hoc Retrieval
In recent years, deep neural networks have led to exciting breakthroughs in
speech recognition, computer vision, and natural language processing (NLP)
tasks. However, there have been few positive results of deep models on ad-hoc
retrieval tasks. This is partially due to the fact that many important
characteristics of the ad-hoc retrieval task have not been well addressed in
deep models yet. Typically, the ad-hoc retrieval task is formalized as a
matching problem between two pieces of text in existing work using deep models,
and treated equivalent to many NLP tasks such as paraphrase identification,
question answering and automatic conversation. However, we argue that the
ad-hoc retrieval task is mainly about relevance matching while most NLP
matching tasks concern semantic matching, and there are some fundamental
differences between these two matching tasks. Successful relevance matching
requires proper handling of the exact matching signals, query term importance,
and diverse matching requirements. In this paper, we propose a novel deep
relevance matching model (DRMM) for ad-hoc retrieval. Specifically, our model
employs a joint deep architecture at the query term level for relevance
matching. By using matching histogram mapping, a feed forward matching network,
and a term gating network, we can effectively deal with the three relevance
matching factors mentioned above. Experimental results on two representative
benchmark collections show that our model can significantly outperform some
well-known retrieval models as well as state-of-the-art deep matching models.Comment: CIKM 2016, long pape
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