9,295 research outputs found
Low-Latency Millimeter-Wave Communications: Traffic Dispersion or Network Densification?
This paper investigates two strategies to reduce the communication delay in
future wireless networks: traffic dispersion and network densification. A
hybrid scheme that combines these two strategies is also considered. The
probabilistic delay and effective capacity are used to evaluate performance.
For probabilistic delay, the violation probability of delay, i.e., the
probability that the delay exceeds a given tolerance level, is characterized in
terms of upper bounds, which are derived by applying stochastic network
calculus theory. In addition, to characterize the maximum affordable arrival
traffic for mmWave systems, the effective capacity, i.e., the service
capability with a given quality-of-service (QoS) requirement, is studied. The
derived bounds on the probabilistic delay and effective capacity are validated
through simulations. These numerical results show that, for a given average
system gain, traffic dispersion, network densification, and the hybrid scheme
exhibit different potentials to reduce the end-to-end communication delay. For
instance, traffic dispersion outperforms network densification, given high
average system gain and arrival rate, while it could be the worst option,
otherwise. Furthermore, it is revealed that, increasing the number of
independent paths and/or relay density is always beneficial, while the
performance gain is related to the arrival rate and average system gain,
jointly. Therefore, a proper transmission scheme should be selected to optimize
the delay performance, according to the given conditions on arrival traffic and
system service capability
Kinematic properties of the dual AGN system J0038+4128 based on long-slit spectroscopy
The study of kiloparsec-scale dual active galactic nuclei (AGN) will provide
important clues to understand the co-evolution between the host galaxies and
their central supermassive black holes undergoing a merging process. We present
long-slit spectroscopy of the J00384128, a kiloparsec-scale dual AGN
candidate discovered by Huang et al. recently, using the Yunnan Faint Object
Spectrograph and Camera (YFOSC) mounted on Li-Jiang 2.4-m telescope at Yunnan
observatories. From the long-slit spectra, we find that the average relative
line-of-sight (LOS) velocity between the two nuclei (J00384128N and
J00384128S) is about 150 km s. The LOS velocities of the emission
lines from the gas ionized by the nuclei activities and of the absorption lines
from stars governed by the host galaxies for different regions of the
J00384128 exhibit the same trend. The same velocities trend indicates that
the gaseous disks are co-rotating with the stellar disks in this ongoing merge
system. We also find several knots/giant HII regions scattered around the two
nuclei with strong star formation revealed by the observed line ratios from the
spectra. Those regions are also detected clearly in HST -band and HST
-band images.Comment: 12 pages, 5 figures, 3 tables, Research in Astronomy and Astrophysics
accepte
Convolutional Graph-Tensor Net for Graph Data Completion
Graph data completion is a fundamentally important issue as data generally
has a graph structure, e.g., social networks, recommendation systems, and the
Internet of Things. We consider a graph where each node has a data matrix,
represented as a \textit{graph-tensor} by stacking the data matrices in the
third dimension. In this paper, we propose a \textit{Convolutional Graph-Tensor
Net} (\textit{Conv GT-Net}) for the graph data completion problem, which uses
deep neural networks to learn the general transform of graph-tensors. The
experimental results on the ego-Facebook data sets show that the proposed
\textit{Conv GT-Net} achieves significant improvements on both completion
accuracy (50\% higher) and completion speed (3.6x 8.1x faster) over the
existing algorithms
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