59 research outputs found
Digital Twin-Driven Network Architecture for Video Streaming
Digital twin (DT) is revolutionizing the emerging video streaming services
through tailored network management. By integrating diverse advanced
communication technologies, DTs are promised to construct a holistic
virtualized network for better network management performance. To this end, we
develop a DT-driven network architecture for video streaming (DTN4VS) to enable
network virtualization and tailored network management. With the architecture,
various types of DTs can characterize physical entities' status, separate the
network management functions from the network controller, and empower the
functions with emulated data and tailored strategies. To further enhance
network management performance, three potential approaches are proposed, i.e.,
domain data exploitation, performance evaluation, and adaptive DT model update.
We present a case study pertaining to DT-assisted network slicing for short
video streaming, followed by some open research issues for DTN4VS.Comment: 8 pages, 5 figures, submitted to IEEE Network Magazin
Digital Twin Based User-Centric Resource Management for Multicast Short Video Streaming
Multicast short video streaming (MSVS) can effectively reduce network traffic
load by delivering identical video sequences to multiple users simultaneously.
The existing MSVS schemes mainly rely on the aggregated video requests to
reserve bandwidth and computing resources, which cannot satisfy users' diverse
and dynamic service requirements, particularly when users' swipe behaviors
exhibit spatiotemporal fluctuation. In this paper, we propose a user-centric
resource management scheme based on the digital twin (DT) technique, which aims
to enhance user satisfaction as well as reduce resource consumption. Firstly,
we design a user DT (UDT)-assisted resource reservation framework.
Specifically, UDTs are constructed for individual users, which store users'
historical data for updating multicast groups and abstracting useful
information. The swipe probability distributions and recommended video lists
are abstracted from UDTs to predict bandwidth and computing resource demands.
Parameterized sigmoid functions are leveraged to characterize multicast groups'
user satisfaction. Secondly, we formulate a joint non-convex bandwidth and
computing resource reservation problem which is transformed into a convex
piecewise problem by utilizing a tangent function to approximately substitute
the concave part. A low-complexity scheduling algorithm is then developed to
find the optimal resource reservation decisions. Simulation results based on
the real-world dataset demonstrate that the proposed scheme outperforms
benchmark schemes in terms of user satisfaction and resource consumption.Comment: 13 pages, 11 figure
Reply to: Mobility overestimation in MoS transistors due to invasive voltage probes
In this reply, we include new experimental results and verify that the
observed non-linearity in rippled-MoS (leading to mobility kink) is an
intrinsic property of a disordered system, rather than contact effects
(invasive probes) or other device issues. Noting that Peng Wu's hypothesis is
based on a highly ordered ideal system, transfer curves are expected to be
linear, and the carrier density is assumed be constant. Wu's model is therefore
oversimplified for disordered systems and neglects carrier-density dependent
scattering physics. Thus, it is fundamentally incompatible with our
rippled-MoS, and leads to the wrong conclusion
Giant All-Optical Modulation of Second-Harmonic Generation Mediated by Dark Excitons.
All-optical control of nonlinear photonic processes in nanomaterials is of significant interest from a fundamental viewpoint and with regard to applications ranging from ultrafast data processing to spectroscopy and quantum technology. However, these applications rely on a high degree of control over the nonlinear response, which still remains elusive. Here, we demonstrate giant and broadband all-optical ultrafast modulation of second-harmonic generation (SHG) in monolayer transition-metal dichalcogenides mediated by the modified excitonic oscillation strength produced upon optical pumping. We reveal a dominant role of dark excitons to enhance SHG by up to a factor of ∼386 at room temperature, 2 orders of magnitude larger than the current state-of-the-art all-optical modulation results. The amplitude and sign of the observed SHG modulation can be adjusted over a broad spectral range spanning a few electronvolts with ultrafast response down to the sub-picosecond scale via different carrier dynamics. Our results not only introduce an efficient method to study intriguing exciton dynamics, but also reveal a new mechanism involving dark excitons to regulate all-optical nonlinear photonics
Difference frequency generation in monolayer MoS2
| openaire: EC/H2020/820423/EU//S2QUIP | openaire: EC/H2020/834742/EU//ATOPDifference frequency generation has long been employed for numerous applications, such as coherent light generation, sensing and imaging. Here, we demonstrate difference frequency generation down to atomic thickness in monolayer molybdenum disulfide. By mixing femtosecond optical pulses at wavelength of 406 nm with tunable pulses in the spectral range of 1300-1520 nm, we generate tunable pulses across the spectral range of 550-590 nm with frequency conversion efficiency up to ∼2 × 10-4. The second-order nonlinear optical susceptibility of monolayer molybdenum disulfide, χ(2)eff, is calculated as ∼1.8 × 10-8 m V-1, comparable to the previous results demonstrated with second harmonic generation. Such a highly efficient down-conversion nonlinear optical process in two-dimensional layered materials may open new ways to their nonlinear optical applications, such as coherent light generation and amplification.Peer reviewe
Simultaneous Use of Stimulatory Agents to Enhance the Production and Hypoglycaemic Activity of Polysaccharides from Inonotus obliquus by Submerged Fermentation
This study aimed to determine the effect of applying stimulatory agents to liquid cultured Inonotus obliquus on the simultaneous accumulation of exo-polysaccharides (EPS) and their monosaccharide composition. Different stimulatory agents (VB6, VB1, betulin and birch extract) were investigated for their effects on active exo-polysaccharides by submerged fermentation of I. obliquus. The mycelial biomass, reducing sugar content, EPS yield and α-glucosidase inhibition rate were determined, and the EPS obtained was analyzed for monosaccharide composition. The results showed that the addition of all the four stimulatory agents could significantly increase the inhibitory activity against α-glucosidase of EPS than the control, whereas EPS from 4 μg/mL VB1-containing medium had the best effect with an estimated IC50 value 24.34 μg/mL. Among the four stimulatory agents, VB6 gave maximum production of mycelial biomass and EPS at the concentration of 4 μg/mL with a increase of 50.79% and 114.46%, respectively. In addition, betulin had a significant effect on increasing the EPS yield and activity, and birch extract had a significantly stimulatory effect on the mycelial growth and the polysaccharides activity, only slightly worse than VB6 and VB1. Moreover, the addition of different stimulatory agents changed the monosaccharide composition of polysaccharides, which had a correlation with polysaccharide activity
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