11,377 research outputs found
Collaborative Spatio-temporal Feature Learning for Video Action Recognition
Spatio-temporal feature learning is of central importance for action
recognition in videos. Existing deep neural network models either learn spatial
and temporal features independently (C2D) or jointly with unconstrained
parameters (C3D). In this paper, we propose a novel neural operation which
encodes spatio-temporal features collaboratively by imposing a weight-sharing
constraint on the learnable parameters. In particular, we perform 2D
convolution along three orthogonal views of volumetric video data,which learns
spatial appearance and temporal motion cues respectively. By sharing the
convolution kernels of different views, spatial and temporal features are
collaboratively learned and thus benefit from each other. The complementary
features are subsequently fused by a weighted summation whose coefficients are
learned end-to-end. Our approach achieves state-of-the-art performance on
large-scale benchmarks and won the 1st place in the Moments in Time Challenge
2018. Moreover, based on the learned coefficients of different views, we are
able to quantify the contributions of spatial and temporal features. This
analysis sheds light on interpretability of the model and may also guide the
future design of algorithm for video recognition.Comment: CVPR 201
Domain wall brane in a reduced Born-Infeld- theory
The Born-Infeld theory is reduced from the Born-Infeld determinantal
gravity in Weitzenb\"ock spacetime. We investigate a braneworld scenario in
this theory and obtain an analytic domain wall solution by utilizing the
first-order formalism. The model is stable against the linear tensor
perturbation. It is shown that the massless graviton is localized on the brane,
but the continuous massive gravitons are non-localized and will generate a tiny
correction with the behavior of to the Newtonian potential.
The four-dimensional teleparallel gravity is recovered as an effective infrared
theory on the brane. As a physical application, we consider the
(quasi-)localization property of spin-1/2 Dirac fermion in this model.Comment: 9 pages, 2 figures, published versio
Modeling Joint Improvisation between Human and Virtual Players in the Mirror Game
Joint improvisation is observed to emerge spontaneously among humans
performing joint action tasks, and has been associated with high levels of
movement synchrony and enhanced sense of social bonding. Exploring the
underlying cognitive and neural mechanisms behind the emergence of joint
improvisation is an open research challenge. This paper investigates the
emergence of jointly improvised movements between two participants in the
mirror game, a paradigmatic joint task example. A theoretical model based on
observations and analysis of experimental data is proposed to capture the main
features of their interaction. A set of experiments is carried out to test and
validate the model ability to reproduce the experimental observations. Then,
the model is used to drive a computer avatar able to improvise joint motion
with a human participant in real time. Finally, a convergence analysis of the
proposed model is carried out to confirm its ability to reproduce the emergence
of joint movement between the participants
Effects of polymer additives in the bulk of turbulent thermal convection
We present experimental evidence that a minute amount of polymer additives
can significantly enhance heat transport in the bulk region of turbulent
thermal convection. The effects of polymer additives are found to be the
\textit{suppression} of turbulent background fluctuations that give rise to
incoherent heat fluxes that make no net contribution to heat transport, and at
the same time to \textit{increase} the coherency of temperature and velocity
fields. The suppression of small-scale turbulent fluctuations leads to more
coherent thermal plumes that result in the heat transport enhancement. The fact
that polymer additives can increase the coherency of thermal plumes is
supported by the measurements of a number of local quantities, such as the
extracted plume amplitude and width, the velocity autocorrelation functions and
the velocity-temperature cross-correlation coefficient. The results from local
measurements also suggest the existence of a threshold value for the polymer
concentration, only above which can significant modification of the plume
coherent properties and enhancement of the local heat flux be observed.
Estimation of the plume emission rate suggests that the second effect of
polymer additives is to stabilize the thermal boundary layers.Comment: 8 figures, 11 page
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