Detection of Highway Pavement Damage Based on a CNN Using Grayscale and HOG Features.

Aiming at the demand for rapid detection of highway pavement damage, many deep learning methods based on convolutional neural networks (CNNs) have been developed. However, CNN methods with raw image data require a high-performance hardware configuration and cost machine time. To reduce machine time and to apply the detection methods in common scenarios, the CNN structure with preprocessed image data needs to be simplified. In this work, a detection method based on a CNN and the combination of the grayscale and histogram of oriented gradients (HOG) features is proposed. First, the Gamma correction was employed to highlight the grayscale distribution of the damage area, which compresses the space of normal pavement. The preprocessed image was then divided into several unit cells, whose grayscale and HOG were calculated, respectively. The grayscale and HOG of each unit cell were combined to construct the grayscale-weighted HOG (GHOG) feature patterns. These feature patterns were input to the CNN with a specific structure and parameters. The trained indices suggested that the performance of the GHOG-based method was significantly improved, compared with the traditional HOG-based method. Furthermore, the GHOG-feature-based CNN technique exhibited flexibility and effectiveness under the same accuracy, in comparison to those deep learning techniques that directly deal with raw data. Since the grayscale has a definite physical meaning, the present detection method possesses a potential application for the further detection of damage details in the future.

Immunosuppressive 9,10-Secosteroids from the Gorgonian Verrucella umbraculum Collected in the South China Sea.

Four new 9,10-secosteroids, verrucellols A-D (1-4), together with 12 known derivatives (5-16) were isolated from the gorgonian Verrucella umbraculum collected in the South China Sea. The structures of the new compounds were established by spectroscopic analysis and comparison with reported data. These compounds exhibited significant suppressive effects on CD4+ T lymphocyte cell differentiation in an in vitro bioassay. This is the first report of 9,10-secosteroids exhibiting immunomodulation activity.

V2Te2O: A Two-Dimensional van der Waals Correlated Metal.

A metastable vanadium oxytelluride V2Te2O is prepared via a topochemical deintercalation of interlayer Rb+ cations in Rb1-δV2Te2O. The new ternary mixed-anion compound crystallizes in a body-centered tetragonal lattice with a = 3.9282(1) Å and c = 13.277(5) Å, containing V2O square nets that are sandwiched by Te-atomic sheets. The charge-neutral [V2OTe2] block layers stack along the c axis with van der Waals forces, which shows a metallic behavior with a dominant T2 dependence for resistivity at low temperatures. The electronic specific-heat coefficient reaches 33.9 mJ K-2 mol-1, ∼4 times that of the electronic structure calculations, suggesting a significant electron-mass renormalization. The electron correlation effect is concurrently demonstrated by the Wilson and Kadowaki-Woods ratios. Neither charge/spin-density wave nor superconductivity was observed down to 0.03 K.

Anomalous Eu valence state and superconductivity in undoped Eu3Bi2S4F4.

We have synthesized a novel europium bismuth sulfofluoride, Eu3Bi2S4F4, by solid-state reactions in sealed evacuated quartz ampules. The compound crystallizes in a tetragonal lattice (space group I4/mmm, a = 4.0771(1) Å, c = 32.4330(6) Å, and Z = 2), in which CaF2-type Eu3F4 layers and NaCl-like BiS2 bilayers stack alternately along the crystallographic c axis. There are two crystallographically distinct Eu sites, Eu(1) and Eu(2) at the Wyckoff positions 4e and 2a, respectively. Our bond valence sum calculation, based on the refined structural data, indicates that Eu(1) is essentially divalent, while Eu(2) has an average valence of ∼ +2.64(5). This anomalous Eu valence state is further confirmed and supported, respectively, by Mössbauer and magnetization measurements. The Eu(3+) components donate electrons into the conduction bands that are mainly composed of Bi 6px and 6py states. Consequently, the material itself shows metallic conduction and superconducts at 1.5 K without extrinsic chemical doping.

Design and synthesis of a new layered thermoelectric material LaPbBiS3O.

A new quinary oxysulfide LaPbBiS3O was designed and successfully synthesized via a solid-state reaction in a sealed evacuated quartz tube. This material, composed of stacked NaCl-like [M4S6] (where M = Pb, Bi) layers and fluorite-type [La2O2] layers, crystallizes in the tetragonal space group P4/nmm with a = 4.0982(1) Å, c = 19.7754(6) Å, and Z = 2. Electrical resistivity and Hall effect measurements demonstrate that it is a narrow gap semiconductor with an activation energy of ∼17 meV. The thermopower and the figure of merit at room temperature were measured to be -52 µV/K and 0.23, respectively, which makes LaPbBiS3O and its derivatives be promising for thermoelectric applications.

Superconductivity in a layered Ta4Pd3Te16 with PdTe2 chains.

Superconductivity in low-dimensional compounds has long attracted much interest. Here we report superconductivity in a low-dimensional ternary telluride Ta4Pd3Te16 in which the repeating layers contain edge-sharing octahedrally coordinated PdTe2 chains along the crystallographic b axis. Measurements of electrical resistivity, magnetic susceptibility and specific heat on the Ta4Pd3Te16 crystals, grown via a self-flux method, consistently demonstrate bulk superconductivity at 4.6 K. Further analyses of the data indicate significant electron-electron interaction, which allows electronic Cooper pairing in the present system.

Variable range hopping conductivity and spin glass behavior in spin-ladder Ba0.6K0.4Fe2Se3 single crystals.

Ba0.6K0.4Fe2Se3 (BKFS) single crystals were investigated by means of measurements of powder x-ray diffraction, temperature-dependent resistivity, anisotropic dc magnetization, ac magnetic susceptibility and specific heat. The powder x-ray diffraction indicates staggered iron displacements along the ladders with short and long Fe-Fe bond lengths (2.64(2) and 2.91(2) Å) variation. The resistivity of BKFS exhibits variable range hopping behavior with ln(ρ) ~ T(-1/2) at low temperature. The magnetic susceptibility χ(T) exhibits a sharp cusp at around 20 K in a zero-field-cooled process. The frequency-dependent ac magnetic susceptibility reveals that the cusp feature is attributable to spin glass behavior. The anisotropic ac magnetic susceptibility indicates that BKFS is probably an anisotropic Heisenberg-like spin glass with its easy magnetization plane perpendicular to the chain direction. The specific heat also supports an insulating and spin glass ground state. Extended Curie-Weiss behavior above 40 K was observed with a reduced effective moment (µ(eff) = 1.66 µ(B)/Fe for H is perpendicular to b and µ(eff) = 1.82 µB/Fe for H is parallel to b) in BKFS, which is close to the spin-only magnetism with S=1/2.

Growth and characterizations of Ba2Ti2Fe2As4O single crystals.

Single crystals of a new iron-based superconductor Ba2Ti2Fe2As4O have been grown successfully via a Ba2As3-flux method in a sealed evacuated quartz tube. Bulk superconductivity with Tc ∼ 21.5 K was demonstrated in resistivity and magnetic susceptibility measurements after the as-grown crystals were annealed at 500 °C in vacuum for a week. X-ray diffraction patterns confirm that the annealed and the as-grown crystals possess the identical crystallographic structure of Ba2Ti2Fe2As4O. Energy-dispersive x-ray spectra indicate that partial Ti/Fe substitution exists in the [Fe2As2] layers and the annealing process redistributes the Ti within the Fe-plane. The ordered Fe-plane stabilized by annealing exhibits superconductivity with magnetic vortex pinned by Ti.

Ba2Ti2Fe2As4O: A new superconductor containing Fe2As2 layers and Ti2O sheets.

We have synthesized a new oxypnictide, Ba2Ti2Fe2As4O, via a solid-state reaction under a vacuum. The compound crystallizes in a body-centered tetragonal lattice, which can be viewed as an intergrowth of BaFe2As2 and BaTi2As2O, thus containing Fe2As2 layers and Ti2O sheets. Bulk superconductivity at 21 K is observed after annealing the as-prepared sample at 773 K for 40 h. In addition, an anomaly in resistivity and magnetic susceptibility around 125 K is revealed, suggesting a charge- or spin-density wave transition in the Ti sublattice.