1,101 research outputs found
A Hybrid Framework of Reinforcement Learning and Convex Optimization for UAV-Based Autonomous Metaverse Data Collection
Unmanned aerial vehicles (UAVs) are promising for providing communication
services due to their advantages in cost and mobility, especially in the
context of the emerging Metaverse and Internet of Things (IoT). This paper
considers a UAV-assisted Metaverse network, in which UAVs extend the coverage
of the base station (BS) to collect the Metaverse data generated at roadside
units (RSUs). Specifically, to improve the data collection efficiency, resource
allocation and trajectory control are integrated into the system model. The
time-dependent nature of the optimization problem makes it non-trivial to be
solved by traditional convex optimization methods. Based on the proposed
UAV-assisted Metaverse network system model, we design a hybrid framework with
reinforcement learning and convex optimization to {cooperatively} solve the
time-sequential optimization problem. Simulation results show that the proposed
framework is able to reduce the mission completion time with a given
transmission power resource.Comment: This paper appears in IEEE Network magazin
TetraÂkis(μ-naphthalene-1-acetato-κ2 O:O′)bisÂ[(N,N-dimethylÂformamide-κO)copper(II)]
The asymmetric unit of the title compound, [Cu2(C12H9O2)4(C3H7NO)2], contains two independent centrosymmetric dinuclear copper(II) complexes. The central paddle-wheel units are formed by four bridging bidentate naphthalene-1-acetate ligands with two dimethylÂformamide ligands in the axial positions. The unique CuII ions have slightly distorted square-pyramidal coordination geometries. One of the naphthalene rings is disordered over two sets of sites, with refined occpancies of 0.535 (4) and 0.465 (4)
Singularity Analysis for a 5-DoF FullySymmetrical Parallel Manipulator 5-RRR (RR
Abstract-A 5-DoF 3R2T (three dimensional rotation and two dimensional translation degrees of freedom) fully-symmetrical parallel manipulator can be adopted in many applications such as simulating the motion of spinal column. However, kinematics of this type parallel manipulator has not been studied enough because of short history. The study of kinematics of the manipulators leads inevitably to the problem of singular configuration. Singularity of a 5-DoF 3R2T fully-symmetrical parallel manipulator, 5-RRR(RR), is illustrated in this study. According to the singularity classification by Fang and Tsai, both limb singularity and actuation singularity are illustrated by screw theory and Grassmann geometry. The result of this study will be helpful for singularity analysis of 5-DoF 3R2T fully-symmetrical parallel manipulators because of their similar constraint property
Recovering the CMB Signal with Machine Learning
The cosmic microwave background (CMB), carrying the inhomogeneous information
of the very early universe, is of great significance for understanding the
origin and evolution of our universe. However, observational CMB maps contain
serious foreground contaminations from several sources, such as galactic
synchrotron and thermal dust emissions. Here, we build a deep convolutional
neural network (CNN) to recover the tiny CMB signal from various huge
foreground contaminations. Focusing on the CMB temperature fluctuations, we
find that the CNN model can successfully recover the CMB temperature maps with
high accuracy, and that the deviation of the recovered power spectrum
is smaller than the cosmic variance at . We then apply this method to
the current Planck observation, and find that the recovered CMB is quite
consistent with that disclosed by the Planck collaboration, which indicates
that the CNN method can provide a promising approach to the component
separation of CMB observations. Furthermore, we test the CNN method with
simulated CMB polarization maps based on the CMB-S4 experiment. The result
shows that both the EE and BB power spectra can be recovered with high
accuracy. Therefore, this method will be helpful for the detection of
primordial gravitational waves in current and future CMB experiments. The CNN
is designed to analyze two-dimensional images, thus this method is not only
able to process full-sky maps, but also partial-sky maps. Therefore, it can
also be used for other similar experiments, such as radio surveys like the
Square Kilometer Array.Comment: 19 pages, 25 figures, and 3 tables, ApJS, in press. The code
repository is available at https://github.com/Guo-Jian-Wang/cmbNNC
Antitumor Cyclic Hexapeptides from Rubia Plants: History, Chemistry, and Mechanism (2005–2011)
Rubiaceae-type cyclopeptides (RAs), cyclic hexapeptides from Rubia plants, have shown potential antitumor activity in vitro and in vivo. Based on the review about plant cyclopeptides (Chem. Rev., 2006, 106: 840), this mini-review will highlight new
progress on the discovery, synthesis, and mechanism of RAs isolated during 2005 to 2011, covering recent work in our group
The influence of net-quarks on the yields and rapidity spectra of identified hadrons
Within a quark combination model, we study systematically the yields and
rapidity spectra of various hadrons in central Au+Au collisions at
GeV. We find that considering the difference in rapidity
between net-quarks and newborn quarks, the data of multiplicities, rapidity
distributions for , , and, in particular the
ratios of charged antihadron to hadron as a function of rapidity, can be well
described. The effect of net-quarks on various hadrons is analysed, and the
rapidity distributions for , ,
, ()
and are predicted. We discuss
the rapidity distribution of net-baryon, and find that it reflects exactly the
energy loss of colliding nuclei.Comment: 8 pages, 7 figure
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