81 research outputs found
Joint and Competitive Caching Designs in Large-Scale Multi-Tier Wireless Multicasting Networks
Caching and multicasting are two promising methods to support massive content
delivery in multi-tier wireless networks. In this paper, we consider a random
caching and multicasting scheme with caching distributions in the two tiers as
design parameters, to achieve efficient content dissemination in a two-tier
large-scale cache-enabled wireless multicasting network. First, we derive
tractable expressions for the successful transmission probabilities in the
general region as well as the high SNR and high user density region,
respectively, utilizing tools from stochastic geometry. Then, for the case of a
single operator for the two tiers, we formulate the optimal joint caching
design problem to maximize the successful transmission probability in the
asymptotic region, which is nonconvex in general. By using the block successive
approximate optimization technique, we develop an iterative algorithm, which is
shown to converge to a stationary point. Next, for the case of two different
operators, one for each tier, we formulate the competitive caching design game
where each tier maximizes its successful transmission probability in the
asymptotic region. We show that the game has a unique Nash equilibrium (NE) and
develop an iterative algorithm, which is shown to converge to the NE under a
mild condition. Finally, by numerical simulations, we show that the proposed
designs achieve significant gains over existing schemes.Comment: 30 pages, 6 pages, submitted to IEEE GLOBECOM 2017 and IEEE Trans.
Commo
Analytic Network Traffic Prediction Based on User Behavior Modeling
This paper proposes an interpretable user-behavior-based (UBB) network
traffic prediction (NTP) method. Based on user behavior, a weekly traffic
demand profile can be naturally sorted into three categories, i.e., weekday,
Saturday, and Sunday. For each category, the traffic pattern is divided into
three components which are mainly generated in three time periods, i.e.,
morning, afternoon, and evening. Each component is modeled as a
normal-distributed signal. Numerical results indicate the UBB NTP method
matches the practical wireless traffic demand very well. Compared with existing
methods, the proposed UBB NTP method improves the computational efficiency and
increases the predictive accuracy.Comment: This paper has been submitted to IEEE Networking Letters for possible
publication
Object as Query: Lifting any 2D Object Detector to 3D Detection
3D object detection from multi-view images has drawn much attention over the
past few years. Existing methods mainly establish 3D representations from
multi-view images and adopt a dense detection head for object detection, or
employ object queries distributed in 3D space to localize objects. In this
paper, we design Multi-View 2D Objects guided 3D Object Detector (MV2D), which
can lift any 2D object detector to multi-view 3D object detection. Since 2D
detections can provide valuable priors for object existence, MV2D exploits 2D
detectors to generate object queries conditioned on the rich image semantics.
These dynamically generated queries help MV2D to recall objects in the field of
view and show a strong capability of localizing 3D objects. For the generated
queries, we design a sparse cross attention module to force them to focus on
the features of specific objects, which suppresses interference from noises.
The evaluation results on the nuScenes dataset demonstrate the dynamic object
queries and sparse feature aggregation can promote 3D detection capability.
MV2D also exhibits a state-of-the-art performance among existing methods. We
hope MV2D can serve as a new baseline for future research.Comment: technical repor
Blockchain-Empowered Mobile Edge Intelligence, Machine Learning and Secure Data Sharing
Driven by recent advancements in machine learning, mobile edge computing (MEC) and the Internet of things (IoT), artificial intelligence (AI) has become an emerging technology. Traditional machine learning approaches require the training data to be collected and processed in centralized servers. With the advent of new decentralized machine learning approaches and mobile edge computing, the IoT on-device data training has now become possible. To realize AI at the edge of the network, IoT devices can offload training tasks to MEC servers. However, those distributed frameworks of edge intelligence also introduce some new challenges, such as user privacy and data security. To handle these problems, blockchain has been considered as a promising solution. As a distributed smart ledger, blockchain is renowned for high scalability, privacy-preserving, and decentralization. This technology is also featured with automated script execution and immutable data records in a trusted manner. In recent years, as quantum computers become more and more promising, blockchain is also facing potential threats from quantum algorithms. In this chapter, we provide an overview of the current state-of-the-art in these cutting-edge technologies by summarizing the available literature in the research field of blockchain-based MEC, machine learning, secure data sharing, and basic introduction of post-quantum blockchain. We also discuss the real-world use cases and outline the challenges of blockchain-empowered intelligence
Decoupled molecular and inorganic framework dynamics in CH3NH3PbCl3
The organic-inorganic lead halide perovskites are composed of organic
molecules imbedded in an inorganic framework. The compounds with general
formula CHNHPbX (MAPbX) display large photovoltaic
efficiencies for halogens =Cl, Br, and I in a wide variety of sample
geometries and preparation methods. The organic cation and inorganic framework
are bound by hydrogen bonds that tether the molecules to the halide anions, and
this has been suggested to be important to the optoelectronic properties. We
have studied the effects of this bonding using time-of-flight neutron
spectroscopy to measure the molecular dynamics in CHNHPbCl
(MAPbCl). Low-energy/high-resolution neutron backscattering reveals
thermally-activated molecular dynamics with a characteristic temperature of
95\,K. At this same temperature, higher-energy neutron spectroscopy
indicates the presence of an anomalous broadening in energy (reduced lifetime)
associated with the molecular vibrations. By contrast, neutron powder
diffraction shows that a spatially long-range structural phase transitions
occurs at 178\,K (cubic tetragonal) and 173\,K (tetragonal
orthorhombic). The large difference between these two temperature
scales suggests that the molecular and inorganic lattice dynamics in MAPbCl
are actually decoupled. With the assumption that underlying physical mechanisms
do not change with differing halogens in the organic-inorganic perovskites, we
speculate that the energy scale most relevant to the photovoltaic properties of
the lead-halogen perovskites is set by the lead-halide bond, not by the
hydrogen bond.Comment: (10 pages, 5 figures, to be published in Physical Review Materials
Mycobacterium smegmatis Induces Neurite Outgrowth and Differentiation in an Autophagy-Independent Manner in PC12 and C17.2 Cells
Both pathogenic and non-pathogenic Mycobacteria can induce the differentiation of immune cells into dendritic cells (DC) or DC-like cells. In addition, pathogenic Mycobacteria is found to stimulate cell differentiation in the nerves system. Whether non-pathogenic Mycobacteria interacts with nerve cells remains unknown. In this study, we found that co-incubation with fast-growing Mycobacteria smegmatis induced neuron-like morphological changes of PC12 and C17.2 cells. Moreover, the M. smegmatis culture supernatant which was ultrafiltrated through a membrane with a 10 kDa cut-off, induced neurite outgrowth and differentiation in an autophagy-independent pathway in PC12 and C17.2 cells. Further analysis showed that IFN-γ production and activation of the PI3K-Akt signaling pathway were involved in the neural differentiation. In conclusion, our finding demonstrated that non-pathogenic M. smegmatis was able to promote neuronal differentiation by its extracellular proteins, which might provide a novel therapeutic strategy for the treatment of neurodegenerative disorders
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