42 research outputs found
Modeling and Design of the Communication Sensing and Control Coupled Closed-Loop Industrial System
With the advent of 5G era, factories are transitioning towards wireless
networks to break free from the limitations of wired networks. In 5G-enabled
factories, unmanned automatic devices such as automated guided vehicles and
robotic arms complete production tasks cooperatively through the periodic
control loops. In such loops, the sensing data is generated by sensors, and
transmitted to the control center through uplink wireless communications. The
corresponding control commands are generated and sent back to the devices
through downlink wireless communications. Since wireless communications,
sensing and control are tightly coupled, there are big challenges on the
modeling and design of such closed-loop systems. In particular, existing
theoretical tools of these functionalities have different modelings and
underlying assumptions, which make it difficult for them to collaborate with
each other. Therefore, in this paper, an analytical closed-loop model is
proposed, where the performances and resources of communication, sensing and
control are deeply related. To achieve the optimal control performance, a
co-design of communication resource allocation and control method is proposed,
inspired by the model predictive control algorithm. Numerical results are
provided to demonstrate the relationships between the resources and control
performances.Comment: 6 pages, 3 figures, received by GlobeCom 202
Throughput of Hybrid UAV Networks with Scale-Free Topology
Unmanned Aerial Vehicles (UAVs) hold great potential to support a wide range
of applications due to the high maneuverability and flexibility. Compared with
single UAV, UAV swarm carries out tasks efficiently in harsh environment, where
the network resilience is of vital importance to UAV swarm. The network
topology has a fundamental impact on the resilience of UAV network. It is
discovered that scale-free network topology, as a topology that exists widely
in nature, has the ability to enhance the network resilience. Besides,
increasing network throughput can enhance the efficiency of information
interaction, improving the network resilience. Facing these facts, this paper
studies the throughput of UAV Network with scale-free topology. Introducing the
hybrid network structure combining both ad hoc transmission mode and cellular
transmission mode into UAV Network, the throughput of UAV Network is improved
compared with that of pure ad hoc UAV network. Furthermore, this work also
investigates the optimal setting of the hop threshold for the selection of ad
hoc or cellular transmission mode. It is discovered that the optimal hop
threshold is related with the number of UAVs and the parameters of scale-free
topology. This paper may motivate the application of hybrid network structure
into UAV Network.Comment: 15 pages, 7 figure
Fast Neighbor Discovery for Wireless Ad Hoc Network with Successive Interference Cancellation
Neighbor discovery (ND) is a key step in wireless ad hoc network, which
directly affects the efficiency of wireless networking. Improving the speed of
ND has always been the goal of ND algorithms. The classical ND algorithms lose
packets due to the collision of multiple packets, which greatly affects the
speed of the ND algorithms. Traditional methods detect packet collision and
implement retransmission when encountering packet loss. However, they does not
solve the packet collision problem and the performance improvement of ND
algorithms is limited. In this paper, the successive interference cancellation
(SIC) technology is introduced into the ND algorithms to unpack multiple
collision packets by distinguishing multiple packets in the power domain.
Besides, the multi-packet reception (MPR) is further applied to reduce the
probability of packet collision by distinguishing multiple received packets,
thus further improving the speed of ND algorithms. Six ND algorithms, namely
completely random algorithm (CRA), CRA based on SIC (CRA-SIC), CRA based on SIC
and MPR (CRA-SIC-MPR), scan-based algorithm (SBA), SBA based on SIC (SBA-SIC),
and SBA based on SIC and MPR (SBA-SIC-MPR), are theoretically analyzed and
verified by simulation. The simulation results show that SIC and MPR reduce the
ND time of SBA by 69.02% and CRA by 66.03% averagely.Comment: 16 pages, 16 figure
Eclipsing Binaries From the CSTAR Project at Dome A, Antarctica
The Chinese Small Telescope ARray (CSTAR) has observed an area around the
Celestial South Pole at Dome A since 2008. About light curves in the i
band were obtained lasting from March to July, 2008. The photometric precision
achieves about 4 mmag at i = 7.5 and 20 mmag at i = 12 within a 30 s exposure
time. These light curves are analyzed using Lomb--Scargle, Phase Dispersion
Minimization, and Box Least Squares methods to search for periodic signals.
False positives may appear as a variable signature caused by contaminating
stars and the observation mode of CSTAR. Therefore the period and position of
each variable candidate are checked to eliminate false positives. Eclipsing
binaries are removed by visual inspection, frequency spectrum analysis and
locally linear embedding technique. We identify 53 eclipsing binaries in the
field of view of CSTAR, containing 24 detached binaries, 8 semi-detached
binaries, 18 contact binaries, and 3 ellipsoidal variables. To derive the
parameters of these binaries, we use the Eclipsing Binaries via Artificial
Intelligence (EBAI) method. The primary and the secondary eclipse timing
variations (ETVs) for semi-detached and contact systems are analyzed.
Correlated primary and secondary ETVs confirmed by false alarm tests may
indicate an unseen perturbing companion. Through ETV analysis, we identify two
triple systems (CSTAR J084612.64-883342.9 and CSTAR J220502.55-895206.7). The
orbital parameters of the third body in CSTAR J220502.55-895206.7 are derived
using a simple dynamical model.Comment: 41 pages, 12 figures; published online in ApJ
Planetary transit candidates in the CSTAR field: analysis of the 2008 data
The Chinese Small Telescope ARray (CSTAR) is a group of four identical, fully automated, static 14.5 cm telescopes. CSTAR is located at Dome A, Antarctica and covers 20 deg2 of sky around the South Celestial Pole. The installation is designed to provide high-cadence photometry for the purpose of monitoring the quality of the astronomical observing conditions at Dome A and detecting transiting exoplanets. CSTAR has been operational since 2008, and has taken a rich and high-precision photometric data set of 10,690 stars. In the first observing season, we obtained 291,911 qualified science frames with 20 s integrations in the i band. Photometric precision reaches 4 mmag at 20 s cadence at i = 7.5 and is 20 mmag at i = 12. Using robust detection methods, 10 promising exoplanet candidates were found. Four of these were found to be giants using spectroscopic follow-up. All of these transit candidates are presented here along with the discussion of their detailed properties as well as the follow-up observations
Evaluation of the quality and reliability of anal cancer and its precancerous lesions-related content on YouTube: a cross-sectional study
Objectives This research aims at evaluating the quality of anal cancer and its precancerous lesions-related videos on YouTube.Design Cross-sectional survey design.Setting USA.Participants The top 150 videos on YouTube were selected for analysis based on three search terms. The duplicate, irrelevant, commercial, operation-related and audio-free videos were excluded. Finally, 105 relevant videos were included.Methods We assessed the completeness of video content from six dimensions and marked the men having sex with men (MSM)-related videos. To measure the video quality, DISCERN, Journal of the American Medical Association (JAMA) Benchmark Criteria, Patient Education Materials Assessment Tool (PEMAT) and Global Quality Scale (GQS) were used. The correlation between DISCERN classification and duration, JAMA, PEMAT and GQS scores were recorded.Results The video content was mainly about the management of the disease (mean score 1.086). Overall, the quality of videos uploaded by the non-profit organisation was relatively high. A correlation existed between each other of the JAMA, DISCERN and GQS scores (p<0.001). Moreover, they were positively correlated with video duration and PEMAT scores (p<0.001).Conclusions Although the overall quality of information about anal cancer and its precancerous lesions videos on YouTube is acceptable, it might not fully meet the health information needs of patients. Therefore, they should exercise caution when using YouTube as a source of anal cancer-related information, especially the MSM population
Study on Quantum Radar Detection Probability Based on Flying-Wing Stealth Aircraft
The development of quantum radar technology presents a challenge to stealth targets, so it is necessary to study the quantum detection probability. In this study, an analytical expression of the quantum radar cross section (QRCS) for complex targets is presented. Based on this QRCS expression, a calculation method for the detection probability for quantum radar is creatively proposed. Moreover, a self-designed flying-wing stealth aircraft is adopted to obtain the detection probability distributions of the conventional radar and the quantum radar in different directions. As revealed by the result of this study, the detection probabilities of the quantum radar and the conventional radar are significantly different, and the detection probability of the quantum radar has obvious advantages in most regions with a certain distance