Study on Traffic Status Threshold Based on Floating Taxi

AbstractThe applications of floating car in road traffic condition identification are taken seriously and gradually developed. The paper studies the variables threshold in traffic condition information based on the floating taxi: section traffic information update cycle, data sampling interval, section covering ratio, floating taxi sample size. The optimization idea of floating taxi sample size is given. The traffic condition identification algorithm based on the floating taxi is put forward. The practice in two road sections shows that the algorithm is feasible which can offer useful reference for urban traffic management and resident trips decision

A Spiking Neural Network Based Cortex-Like Mechanism and Application to Facial Expression Recognition

In this paper, we present a quantitative, highly structured cortex-simulated model, which can be simply described as feedforward, hierarchical simulation of ventral stream of visual cortex using biologically plausible, computationally convenient spiking neural network system. The motivation comes directly from recent pioneering works on detailed functional decomposition analysis of the feedforward pathway of the ventral stream of visual cortex and developments on artificial spiking neural networks (SNNs). By combining the logical structure of the cortical hierarchy and computing power of the spiking neuron model, a practical framework has been presented. As a proof of principle, we demonstrate our system on several facial expression recognition tasks. The proposed cortical-like feedforward hierarchy framework has the merit of capability of dealing with complicated pattern recognition problems, suggesting that, by combining the cognitive models with modern neurocomputational approaches, the neurosystematic approach to the study of cortex-like mechanism has the potential to extend our knowledge of brain mechanisms underlying the cognitive analysis and to advance theoretical models of how we recognize face or, more specifically, perceive other people’s facial expression in a rich, dynamic, and complex environment, providing a new starting point for improved models of visual cortex-like mechanism

Chern insulators and high Curie temperature Dirac half-metal in two-dimensional metal-organic frameworks

Two-dimensional (2D) magnetic materials with nontrivial topological states have drawn considerable attention recently. Among them, 2D metal-organic frameworks (MOFs) are standing out due to their advantages, such as the easy synthesis in practice and less sensitivity to oxidation that are distinctly different from inorganic materials. By means of density-functional theory calculations, we systematically investigate the electronic and topological properties of a class of 2D MOFs X(C21H15N3) (X = transition metal element from 3d to 5d). Excitingly, we find that X(C21H15N3) (X = Ti, Zr, Ag, Au) are Chern insulators with sizable band gaps (~7.1 meV). By studying a four-band effective model, it is revealed that the Chern insulator phase in X(C21H15N3) (X = Ti, Zr, Ag, Au) is caused cooperatively by the band inversion of the p orbitals of the C21H15N3 molecule and the intrinsic ferromagnetism of X(C21H15N3). Additionally, Mn(C21H15N3) is a Dirac half-metal ferromagnet with a high Curie temperature up to 156 K. Our work demonstrates that 2D MOFs X(C21H15N3) are good platforms for realizing Quantum anomalous Hall effect and designing novel spintronic devices based on half-metals with high-speed and long-distance spin transport.Comment: 16 pages, 4 figure

Room-temperature antiferromagnetic CrSe monolayer with tunable metal-insulator transition in ferroelectric heterostructures

Recently, there has been a rapidly growing interest in two-dimensional (2D) transition metal chalcogenide monolayers (MLs) due to their unique magnetic and electronic properties. By using an evolutionary algorithm and first-principles calculations, we report the discovery of a previously unexplored, chemically, energetically, and thermodynamically stable 2D antiferromagnetic (AFM) CrSe ML with a N\'eel temperature higher than room temperature. Remarkably, we predict an electric field-controllable metal-insulator transition (MIT) in a van der Waals (vdW) heterostructure comprised of CrSe ML and ferroelectric Sc2CO2. This tunable transition in CrSe/Sc2CO2 heterostructure is attributed to the change in the band alignment between CrSe and Sc2CO2 caused by the ferroelectric polarization reversal in Sc2CO2. Our findings suggest that 2D AFM CrSe ML has important potential applications in AFM spintronics, particularly in the gate voltage conducting channel.Comment: 13 Pages, 4 Figure

Electrically tunable Gilbert damping in van der Waals heterostructures of two-dimensional ferromagnetic metals and ferroelectrics

Tuning the Gilbert damping of ferromagnetic (FM) metals via a nonvolatile way is of importance to exploit and design next-generation novel spintronic devices. Through systematical first-principles calculations, we study the magnetic properties of the van der Waals heterostructure of two-dimensional FM metal CrTe2 and ferroelectric (FE) In2Te3 monolayers. The ferromagnetism of CrTe2 is maintained in CrTe2/In2Te3 and its magnetic easy axis can be switched from in-plane to out-of-plane by reversing the FE polarization of In2Te3. Excitingly, we find that the Gilbert damping of CrTe2 is tunable when the FE polarization of In2Te3 is reversed from upward to downward. By analyzing the k-dependent contributions to the Gilbert damping, we unravel that such tunability results from the changed intersections between the bands of CrTe2 and Fermi level on the reversal of the FE polarizations of In2Te3 in CrTe2/In2Te3. Our work provides an appealing way to electrically tailor Gilbert dampings of two-dimensional FM metals by contacting them with ferroelectrics.Comment: 4 Figures, accepted by Applied Physics Letter

Bs0→η(′)η(′)B_s^0 \to \eta^{(\prime)} \eta^{(\prime)} decays in the pQCD approach

We calculate the CP averaged branching ratios and CP-violating asymmetries for $B_s^0 \to \eta \eta, \eta \eta^\prime$ and $\eta^\prime \eta^\prime$ decays in the perturbative QCD (pQCD) approach here. The pQCD predictions for the CP-averaged branching ratios are Br(B_s^0 \to \eta \eta) = \left (14.2^{+18.0}_{-7.5}) \times 10^{-6}, Br(B_s^0 \to \eta \eta^\prime)= \left (12.4 ^{+18.2}_{-7.0}) \times 10^{-6}, and Br(B_s^0 \to \eta^{\prime} \eta^{\prime}) = \left (9.2^{+15.3}_{-4.9}) \times 10^{-6}, which agree well with those obtained by employing the QCD factorization approach and also be consistent with available experimental upper limits. The gluonic contributions are small in size: less than 7% for $B_s \to \eta \eta$ and $\eta \eta^\prime$ decays, and around 18% for $B_s \to \eta' \eta'$ decay. The CP-violating asymmetries for three decays are very small: less than 3% in magnitude.Comment: 11 pages, 1 ps figure, Revte

Aqua­(2-hydr­oxy-5-sulfonatobenzoato-κO 1)bis­(2-phenyl-1H-1,3,7,8-tetra­aza­cyclo­penta­[l]phenanthrene-κ2 N 7,N 8)zinc(II)

In the title compound, [Zn(C7H4O6S)(C19H12N4)2(H2O)], the ZnII ion is coordinated by two N,N′-bidentate 2-phenyl-1H-1,3,7,8-tetra­azacyclo­penta­[l]phenanthrene ligands, one O-monodentate 5-sulfosalicylate dianion and a water mol­ecule. This results in a distorted cis-ZnO2N4 octa­hedral coordination geometry for the metal ion. In the crystal, mol­ecules are expanded into a three-dimensional supra­molecular motif via O—H⋯O, O—H⋯N and N—H⋯(O,S) hydrogen bonds. In addition, π–π stacking inter­actions between the aromatic rings of the polycyclic ligands consolidate the sturcture [shortest centroid–centroid distance = 3.501 (2) Å]

Ceramic Nano-particle/Substrate Interface Bonding Formation Derived from Dynamic Mechanical Force at Room Temperature: HRTEM Examination

The bonding of TiO nano-particle/substrate is a critical factor influencing the performance of dye-sensitized solar cells. In order to reveal the bonding properties at TiO nano-particle/substrate interface, high-resolution transmission electron microscopy (HRTEM) analysis was adopted to TiO coatings prepared by three different approaches. In the HRTEM analysis, the effective bonding mode is allowed to distinguish from the false image overlapping. Results show that large areas of effective bonding between nano-TiO particles and the substrate surface formed in the room temperature cold sprayed coating and mechanically pressed coating, while only limited interface areas with the effective bonding were observed in the coating deposited by non-pressed method. These results confirm that both high impact pressure during the room temperature cold spraying and mechanical pressure contribute to the bonding formation at the particle/substrate interface