14,273 research outputs found
Action4D: Real-time Action Recognition in the Crowd and Clutter
Recognizing every person's action in a crowded and cluttered environment is a
challenging task. In this paper, we propose a real-time action recognition
method, Action4D, which gives reliable and accurate results in the real-world
settings. We propose to tackle the action recognition problem using a holistic
4D "scan" of a cluttered scene to include every detail about the people and
environment. Recognizing multiple people's actions in the cluttered 4D
representation is a new problem. In this paper, we propose novel methods to
solve this problem. We propose a new method to track people in 4D, which can
reliably detect and follow each person in real time. We propose a new deep
neural network, the Action4D-Net, to recognize the action of each tracked
person. The Action4D-Net's novel structure uses both the global feature and the
focused attention to achieve state-of-the-art result. Our real-time method is
invariant to camera view angles, resistant to clutter and able to handle crowd.
The experimental results show that the proposed method is fast, reliable and
accurate. Our method paves the way to action recognition in the real-world
applications and is ready to be deployed to enable smart homes, smart factories
and smart stores
Frequency Offset Estimation for OFDM Systems with a Novel Frequency Domain Training Sequence
A novel frequency domain training sequence and the corresponding carrier
frequency offset (CFO) estimator are proposed for orthogonal frequency division
multiplexing (OFDM) systems over frequency-selective fading channels. The
proposed frequency domain training sequence comprises two types of pilot tones,
namely distinctively spaced pilot tones with high energies and uniformly spaced
ones with low energies. Based on the distinctively spaced pilot tones, integer
CFO estimation is accomplished. After the subcarriers occupied by the
distinctively spaced pilot tones and their adjacent subcarriers are nulled for
the sake of interference cancellation, fractional CFO estimation is executed
according to the uniformly spaced pilot tones. By exploiting a predefined
lookup table making the best of the structure of the distinctively spaced pilot
tones, computational complexity of the proposed CFO estimator can be decreased
considerably. With the aid of the uniformly spaced pilot tones generated from
Chu sequence with cyclically orthogonal property, the ability of the proposed
estimator to combat multipath effect is enhanced to a great extent. Simulation
results illustrate the good performance of the proposed CFO estimator.Comment: 11 pages, 9 figures, IEICE Trans. Commun., 200
SNR Degradation due to Carrier Frequency Offset in OFDM based Amplify-and-Forward Relay Systems
In this letter, signal-to-noise ratio (SNR) performance is analyzed for
orthogonal frequency division multiplexing (OFDM) based amplify-and-forward
(AF) relay systems in the presence of carrier frequency offset (CFO) for fading
channels. The SNR expression is derived under one-relay-node scenario, and is
further extended to multiple-relay-node scenario. Analytical results show that
the SNR is quite sensitive to CFO and the sensitivity of the SNR to CFO is
mainly determined by the power of the corresponding link channel and gain
factor.Comment: 4 pages, 4 figures, IEICE Trans. Commu
The Quantum Orbifold Cohomology of Toric Stack Bundles
We study Givental's Lagrangian cone for the quantum orbifold cohomology of
toric stack bundles and prove that the I-function gives points in the
Lagrangian cone, namely we construct an explicit slice of the Lagrangian cone
defined by the genus Gromov-Witten theory of a toric stack bundle.Comment: 23 pages, revised according to the referees' report
Frequency Offset Estimation and Training Sequence Design for MIMO OFDM
This paper addresses carrier frequency offset (CFO) estimation and training
sequence design for multiple-input multiple-output (MIMO) orthogonal frequency
division multiplexing (OFDM) systems over frequency selective fading channels.
By exploiting the orthogonality of the training sequences in the frequency
domain, integer CFO (ICFO) is estimated. {With the uniformly spaced non-zero
pilots in the training sequences} and the corresponding geometric mapping,
fractional CFO (FCFO) is estimated through the roots of a real polynomial.
Furthermore, the condition for the training sequences to guarantee estimation
identifiability is developed. Through the analysis of the correlation property
of the training sequences, two types of sub-optimal training sequences
generated from the Chu sequence are constructed. Simulation results verify the
good performance of the CFO estimator assisted by the proposed training
sequences.Comment: 12 pages, 5 figures, IEEE TWC, 200
Two-body state with p-wave interaction in one-dimensional waveguides under transversely anisotropic confinement
We theoretically study two atoms with -wave interaction in a
one-dimensional waveguide, and investigate how the transverse anisotropy of the
confinement affects the two-body state, especially, the properties of the
resonance. For bound-state solution, we find there are totally three two-body
bound states due to the richness of the orbital magnetic quantum number of
-wave interaction, while only one bound state is supported by -wave
interaction. Two of them become nondegenerate due to the breaking of the
rotation symmetry under transversely anisotropic confinement. For scattering
solution, the effective one-dimensional scattering amplitude and scattering
length are derived. We find the position of the -wave confinement-induced
resonance shifts apparently as the transverse anisotropy increases. In
addition, a two-channel mechanism for confinement-induced resonance in a
one-dimensional waveguide is generalized to -wave interaction, which was
proposed only for -wave interaction before. All our calculations are based
on the parameterization of the K atom experiments, and can be confirmed
in future experiments.Comment: 8 pages, 5 figure
Simplified Frequency Offset Estimation for MIMO OFDM Systems
This paper addresses a simplified frequency offset estimator for
multiple-input multiple-output (MIMO) orthogonal frequency division
multiplexing (OFDM) systems over frequency selective fading channels. By
exploiting the good correlation property of the training sequences, which are
constructed from the Chu sequence, carrier frequency offset (CFO) estimation is
obtained through factor decomposition for the derivative of the cost function
with great complexity reduction. The mean-squared error (MSE) of the CFO
estimation is derived to optimize the key parameter of the simplified estimator
and also to evaluate the estimator performance. Simulation results confirm the
good performance of the training-assisted CFO estimator.Comment: 5 pages, 3 figures, IEEE TVT, 200
Energy Efficient Power Control for the Two-tier Networks with Small Cells and Massive MIMO
In this paper, energy efficient power control for the uplink two-tier
networks where a macrocell tier with a massive multiple-input multiple-output
(MIMO) base station is overlaid with a small cell tier is investigated. We
propose a distributed energy efficient power control algorithm which allows
each user in the two-tier network taking individual decisions to optimize its
own energy efficiency (EE) for the multi-user and multi-cell scenario. The
distributed power control algorithm is implemented by decoupling the EE
optimization problem into two steps. In the first step, we propose to assign
the users on the same resource into the same group and each group can optimize
its own EE, respectively. In the second step, multiple power control games
based on evolutionary game theory (EGT) are formulated for each group, which
allows each user optimizing its own EE. In the EGT-based power control games,
each player selects a strategy giving a higher payoff than the average payoff,
which can improve the fairness among the users. The proposed algorithm has a
linear complexity with respect to the number of subcarriers and the number of
cells in comparison with the brute force approach which has an exponential
complexity. Simulation results show the remarkable improvements in terms of
fairness by using the proposed algorithm.Comment: 6 pages, 4 figures, IEEE Wireless Communications and Networking
Conference Workshops (WCNCW'16
Implicit and electrostatic Particle-in-cell/Monte Carlo model in two dimensional and axisymmetric geometry I: analysis of numerical techniques
We developed an implicit Particle-in-cell/Monte Carlo model in
two-dimensional and axisymmetric geometry for the simulations of the
radio-frequency discharges, by introducing several numerical schemes which
include variable weights, multigrid field solver, etc. Compared to the standard
explicit models, we found that the computational efficiency is significantly
increased and the accuracy is still kept. Numerical schemes are discussed and
benchmark results are shown. The code can be used to simulate practical
reactors.Comment: accepted by Plasma Source Sci. Tec
Holonomic Surface Codes for Fault-Tolerant Quantum Computation
Surface codes can protect quantum information stored in qubits from local
errors as long as the per-operation error rate is below a certain threshold.
Here we propose holonomic surface codes by harnessing the quantum holonomy of
the system. In our scheme, the holonomic gates are built via auxiliary qubits
rather than the auxiliary levels in multilevel systems used in conventional
holonomic quantum computation. The key advantage of our approach is that the
auxiliary qubits are in their ground state before and after each gate
operation, so they are not involved in the operation cycles of surface codes.
This provides an advantageous way to implement surface codes for fault-tolerant
quantum computation.Comment: 14 pages, 6 figure
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