34,342 research outputs found
A 2D systems approach to iterative learning control for discrete linear processes with zero Markov parameters
In this paper a new approach to iterative learning control for the practically relevant case of deterministic discrete linear plants with uniform rank greater than unity is developed. The analysis is undertaken in a 2D systems setting that, by using a strong form of stability for linear repetitive processes, allows simultaneous con-sideration of both trial-to-trial error convergence and along the trial performance, resulting in design algorithms that can be computed using Linear Matrix Inequalities (LMIs). Finally, the control laws are experimentally verified on a gantry robot that replicates a pick and place operation commonly found in a number of applications to which iterative learning control is applicable
Gap opening in the zeroth Landau level in gapped graphene: Pseudo-Zeeman splitting in an angular magnetic field
We present a theoretical study of gap opening in the zeroth Landau level in
gapped graphene as a result of pseudo-Zeeman interaction. The applied magnetic
field couples with the valley pseudospin degree of freedom of the charge
carriers leading to the pseudo-Zeeman interaction. To investigate its role in
transport at the Charge Neutrality Point (CNP), we study the integer quantum
Hall effect (QHE) in gapped graphene in an angular magnetic field in the
presence of pseudo-Zeeman interaction. Analytical expressions are derived for
the Hall conductivity using Kubo-Greenwood formula. We also determine the
longitudinal conductivity for elastic impurity scattering in the first Born
approximation. We show that pseudo-Zeeman splitting leads to a minimum in the
collisional conductivity at high magnetic fields and a zero plateau in the Hall
conductivity. Evidence for activated transport at CNP is found from the
temperature dependence of the collisional conductivity.Comment: 20 pages, 4 figures, Accepted in J. Phys. Condensed matte
Brane World in a Topological Black Hole Bulk
We consider a static brane in the background of a topological black hole, in
arbitrary dimensions. For hyperbolic horizons, we find a solution only when the
black hole mass assumes its minimum negative value. In this case, the tension
of the brane vanishes, and the brane position coincides with the location of
the horizon. For an elliptic horizon, we show that the massless mode of
Randall-Sundrum is recovered in the limit of large black hole mass.Comment: Latex, 8 pages, v2: Additional references, to appear in MPL
Long-Term Human Video Generation of Multiple Futures Using Poses
Predicting future human behavior from an input human video is a useful task
for applications such as autonomous driving and robotics. While most previous
works predict a single future, multiple futures with different behavior can
potentially occur. Moreover, if the predicted future is too short (e.g., less
than one second), it may not be fully usable by a human or other systems. In
this paper, we propose a novel method for future human pose prediction capable
of predicting multiple long-term futures. This makes the predictions more
suitable for real applications. Also, from the input video and the predicted
human behavior, we generate future videos. First, from an input human video, we
generate sequences of future human poses (i.e., the image coordinates of their
body-joints) via adversarial learning. Adversarial learning suffers from mode
collapse, which makes it difficult to generate a variety of multiple poses. We
solve this problem by utilizing two additional inputs to the generator to make
the outputs diverse, namely, a latent code (to reflect various behaviors) and
an attraction point (to reflect various trajectories). In addition, we generate
long-term future human poses using a novel approach based on unidimensional
convolutional neural networks. Last, we generate an output video based on the
generated poses for visualization. We evaluate the generated future poses and
videos using three criteria (i.e., realism, diversity and accuracy), and show
that our proposed method outperforms other state-of-the-art works
Entropic force and its cosmological implications
We investigate a possibility of realizing the entropic force into the
cosmology. A main issue is how the holographic screen is implemented in the
Newtonian cosmology. Contrary to the relativistic realization of Friedmann
equations, we do not clarify the connection between Newtonian cosmology and
entropic force because there is no way of implementing the holographic screen
in the Newtonian cosmology.Comment: 16 pages, no figures, version "Accepted for publication in
Astrophysics & Space Science
Finite-size effects on the magnetoelectric response of field-driven ferroelectric/ferromagnetic chains
We study theoretically the coupled multiferroic dynamics of one-dimensional
ferroelectric/ferromagnet chains driven by harmonic magnetic and electric
fields as a function of the chain length. A linear magnetoelectric coupling is
dominated by the spin-polarized screening charge at the interface. We performed
Monte-Carlo simulations and calculations based on the coupled
Landau-Lifshitz-Gilbert and Landau-Khalatnikov equations showing that the net
magnetization and the total polarization of thin heterostructures, i.e. with up
to ten ferroelectric and ferromagnetic sites counted from the interface, can be
completely reversed by external electric and magnetic fields, respectively.
However, for larger system solely a certain magnetoelectrical control can be
achieved.Comment: J. Phys.: Conf. Series. (2011) (to be published
Wavelet Estimation for Samples With Random Uniform Design
We show that for nonparametric regression if the samples have random uniform design, the wavelet method with universal thresholding can be applied directly to the samples as if they were equispaced. The resulting estimator achieves within a logarithmic factor from the minimax rate of convergence over a family of Hölder classes. Simulation result is also discussed
Entanglement Entropy and Wilson Loop in St\"{u}ckelberg Holographic Insulator/Superconductor Model
We study the behaviors of entanglement entropy and vacuum expectation value
of Wilson loop in the St\"{u}ckelberg holographic insulator/superconductor
model. This model has rich phase structures depending on model parameters. Both
the entanglement entropy for a strip geometry and the heavy quark potential
from the Wilson loop show that there exists a "confinement/deconfinement" phase
transition. In addition, we find that the non-monotonic behavior of the
entanglement entropy with respect to chemical potential is universal in this
model. The pseudo potential from the spatial Wilson loop also has a similar
non-monotonic behavior. It turns out that the entanglement entropy and Wilson
loop are good probes to study the properties of the holographic superconductor
phase transition.Comment: 23 pages,12 figures. v2: typos corrected, accepted in JHE
Delay-Coordinates Embeddings as a Data Mining Tool for Denoising Speech Signals
In this paper we utilize techniques from the theory of non-linear dynamical
systems to define a notion of embedding threshold estimators. More specifically
we use delay-coordinates embeddings of sets of coefficients of the measured
signal (in some chosen frame) as a data mining tool to separate structures that
are likely to be generated by signals belonging to some predetermined data set.
We describe a particular variation of the embedding threshold estimator
implemented in a windowed Fourier frame, and we apply it to speech signals
heavily corrupted with the addition of several types of white noise. Our
experimental work seems to suggest that, after training on the data sets of
interest,these estimators perform well for a variety of white noise processes
and noise intensity levels. The method is compared, for the case of Gaussian
white noise, to a block thresholding estimator
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