[en] A new molybdenum phosphide (MoP) catalyst was successfully synthesized for CO/sub 2/ reforming of CH/sub 4/ reaction. The catalysts were prepared by temperature-programmed reduction (TPR) of phosphomolybdate precursors which were modified by citric acid (CA) at the molar ratio of MoP:CA = 1: x (x = 0, 1.0, 2.0, 3.0), which were characterized by means of X-ray diffraction(XRD), N/sub 2/ adsorption-desorption and CO/sub 2/-TPD techniques. The results showed that the addition of citric acid can affect the catalytic activity and that the MoP catalyst had the highest catalytic activity at 1073 K and X=1. After reduced in H2 flow at 923 K, the activity of the post-reaction catalyst can be well restored, while its structure remains unchanged. In higher temperatures, the samples exhibit good anti-sintering ability and stability. (author)

[en] Using the high time resolution of 1 ms, the data of solar microwave millisecond spike (MMS) event was recorded more than two hundred times at the frequency of 2.84 GHz at Beijing (Peking) Observatory since May 1981. A preliminary analysis was made. It can be seen from the data that the MMS-events have a variety of the fast activities such as the dispersed and isolated spikes, the clusters of the crowded spikes, the weak spikes superimposed on the noise background, and the phenomena of absorption. The marked differences from that observed with lower time resolution are presented. Using the data, a valuable statistical analysis was made. There are close correlations between MMS-events and hard x ray bursts, and fast drifting bursts. The MMS events are highly dependent on the type of active regions and the magnetic field configuration. It seems to be crucial to find out the accurate positions on the active region where the MMS-events happen and to make co-operative observations at different bands during the special period when specific active regions appear on the solar disk

[en] A patterned array of diamond-like carbon (DLC) was grown on anodic aluminum oxide (AAO) template by filtered cathodic arc plasma (FCAP) technique at room temperature. The diameters of patterned array of DLC were ∼150 nm, and the patterned array density was estimated to ∼10⁹ cm^-2. A broad asymmetric band ranging from 1000 cm^-1 to 2000 cm^-1 was detected by Raman spectrum attributed to characteristic band of DLC. The fraction of sp³ bonded carbon atoms of the patterned array of DLC was measured by X-ray photoelectron spectrum (XPS) and the ratio was about 62.4%. Field emission properties of the patterned array of DLC were investigated. A low turn-on field of 3.4 V/μm at 10 μA/cm² with an emission area of 3.14 mm² was achieved. The results indicated that the electrons were emitted under both the effect of enhanced field because of the geometry and the work function of the DLC sample. Based on Fowler-Nordheim plot, the values of work function for the patterned array of DLC were estimated in range of 0.38 to 1.75 from a linearity plot

[en] Awl-shaped diamond-like carbon (DLC) was directly grown on anodic aluminum oxide (AAO) template by using filtered cathodic arc plasma (FCAP) technique at room temperature. The awls of DLC were about 250 nm in the height and the diameters of the awls were ∼100 nm at the top. The awl density was estimated to be ∼10⁸ cm^-2. A broad asymmetric band ranging from 1100 to 1800 cm^-1 was detected by Raman spectrum. This asymmetric band was characteristic band of DLC. The sp³/(sp³+sp²) ratio of C-C bond of the awl-shaped DLC was measured by X-ray photoelectron spectrum, and it was about 68.3%. Field-emission properties of the awl-shaped DLC were investigated. A low turn-on field of 2.6 V/μm at 10 μA/cm² with an emission area of 3.14 mm² was achieved, and the emission current stability was very good. The results indicated that the electrons were emitted under both the effect of enhanced field because of the geometry and the work function of the DLC sample. Based on Fowler-Nordheim plot, the values of work function for the awl-shaped DLC were estimated in ranges of 0.23-1.08 from a linearity plot

[en] The lateral restorable characteristics of a translational symmetry high-T_c superconducting maglev system are investigated by measuring its resonant frequency (f_RF) after a lateral displacement. The difference between whether this lateral displacement is restorable, meaning elastic or inelastic, is determined by whether or not the maglev body returns to its original position after a lateral displacement. The maximum restorable lateral displacement (δ_MRLD) is determined by the sudden change of the f_RF vs. the maximum lateral displacement (δ_MLD) curve. The f_RF of the high-T_c superconducting maglev system with different field-cooling height (FCH) and working height (WH) was obtained from the frequency domain vibration curve which was measured by a vibration measurement system. The results showed that, the δ_MRLD was reduced when the WH was decreased. The maximum restorable guidance force (F_MRGF) was found to not always increase with the lowering of the WH for the same FCH. The lateral restorable stiffness (k_LRS) was always enhanced with the decrease of the WH. The decrease of the δ_MRLD with the WH is interpreted by the fact that, the tangential field component (ΔH) across the surface of the high-T_c superconductor (HTSC) is easier to exceed the J_cλ value (J_c is the critical current density and λ is the London penetration depth) when the WH is lowered, and this makes the trapped flux lines become more susceptible in escaping its pinning sites.

[en] Inverse identification of radiative properties of participating media is usually time consuming. In this paper, a GPU accelerated inverse identification model is presented to obtain the radiative properties of particle suspensions. The sample medium is placed in a cuvette and a narrow light beam is irradiated normally from the side. The forward three-dimensional radiative transfer problem is solved using a massive parallel Monte Carlo method implemented on graphics processing unit (GPU), and particle swarm optimization algorithm is applied to inversely identify the radiative properties of particle suspensions based on the measured bidirectional scattering distribution function (BSDF). The GPU-accelerated Monte Carlo simulation significantly reduces the solution time of the radiative transfer simulation and hence greatly accelerates the inverse identification process. Hundreds of speedup is achieved as compared to the CPU implementation. It is demonstrated using both simulated BSDF and experimentally measured BSDF of microalgae suspensions that the radiative properties of particle suspensions can be effectively identified based on the GPU-accelerated algorithm with three-dimensional radiative transfer modelling. - Highlights: • A GPU accelerated inverse model to obtain radiative properties of particle suspensions. • Demonstrated over 100x speedup for the GPU accelerated inverse model than the CPU implementation. • Presented a sensitivity analysis to understand uncertainties of retrieved radiative parameters. • Tests using experimental data to retrieve radiative properties of microalgae.

[en] A bulk metallic glass composite (BMGC) with a composition of Ti_65.6Cu_13.2Pd_5.6Sn_3.6Nb₁₂ was prepared via suction casting. Microstructure mainly consisting of fine β-Ti dendrites sized about 5 µm and nano-scale interdendritic glassy matrix was obtained in the BMGC. The mechanical behavior was compared with that of the same alloy in a polycrystalline state under compressive and bending conditions. It was found that the nano-scale glassy matrix with limited volume fraction remarkably increased the yield strength of the BMGC, furthermore, plastic deformability of the corresponding polycrystalline alloy could be preserve by the BMGC. Upon loading, the nano-scale glassy matrix could exert a strong restriction effect on the slip deformation inside the micron-scale dendritic crystals; no obvious shear-banding was exhibited in the glassy matrix during the deformation. This deformation characteristic might be attributed to the possible homogeneous deformation mode of the glassy matrix at the nano-scale.

[en] ZnO thin film has been deposited on the glass substrate at a temperature of 200 deg. C using the filtered cathodic arc plasma (FCAP) technique with the oxygen flow rate of 1.0, 3.0, 5.0, 7.0, 9.0 and 10.0 sccm. The deposition processes are only held in pure oxygen atmosphere. The as-grown films exhibit a polycrystalline hexagonal wurtzite structure. With the oxygen flow rate increase, the crystallinity of the samples first increases and then decreases as measured by X-ray diffractometry (XRD). And the tensile stress exists in all the as-grown thin films. The small grain with a mean diameter of 13 nm is observed by the field emission scanning electron microscopy (FESEM). The electrical resistivity values of the thin films are very low ranging from 5.42 x 10^-3 Ω cm to 4.0 x 10^-2 Ω cm. According to the result from room temperature photoluminescence spectra measurement, the luminescent bands also depend on the oxygen supply

[en] Highlights: • Microalloying of carbon (0.03 wt%) for base material within a limited scope was beneficial for CGHAZ. • An increase of carbon from 0.03 to 0.06 wt% in base material alters the shearing mechanism of CGHAZ dramatically. • The possible correlation between crystallographic structure of CGHAZ and CTOD property of HAZ was elaborated. -- Abstract: The carbon is one of the basic alloying solutes in steels. In the present study, the newly carbon microalloyed X80 steel was designed for the next generation of pipeline and the carbon microalloying effect of base material on the crystallographic structure of coarse grained heat affected zone (CGHAZ) of X80 girth welded joints was systematically investigated using electron back-scattering diffraction (EBSD), considering the fact that crystallography is the most intrinsic aspect in evaluating the microstructure. The results indicated a remarkable variation in the density of high angle grain boundaries and their dispersion by increasing the carbon content of 0.03wt%. It was attributed to the differential shearing mechanism, which was primarily sheared by variant pairing of V1/V2 at 0.06 wt% carbon, whereas at lower 0.03wt% carbon, V1/V4 pairing mechanism dominated the transformation. The preferential variant pairing transformation mechanism at differential carbon content therefore generated dissimilarly selected variants. Thus, as the carbon content increased, the variant selection effect upon phase transformation was attenuated by generating more variants from different Bain groups. The variant pair V1/V2 belonging to different Bain groups neighboring in CGHAZ of high carbon steel increased the density of high angle boundary (Σ3 boundary). Moreover, the variation in CTOD (crack-tip opening displacement) property of HAZ suggested that it should be primarily correlated to the block size (or density of block boundaries) of CGHAZ.

[en] Highlights: • Crystallographic structure evolution in CGHAZ caused by variation of prior austenite grain size was analyzed quantitatively. • Variant selection rules changed from CP (close-packed plane) to Bain grouping with decreasing of prior austenite grain size. • A possible correlation between impact toughness scatter and crystallographic structure was established. - Abstract: This study aims at providing a new insights into the impact toughness scatter from the aspect of crystallographic structure. It demonstrated that the large impact toughness scatter associated much to the microstructure diversity. The crystallographic structure with evident scatter will display obvious discrepancy. In this work, three groups of samples simulated coarse-grained heat affected zone (CGHAZ) of an offshore engineering steel were obtained at different cooling rates. The Charpy test results showed that the toughness decreases dramatically with the decrease of cooling rate. However, the largest scatter in impact toughness occurred in the sample with medium cooling rate (15 °C/s), which was attributed to the heterogeneity in crystallographic structures. The visualization of crystallographic features showed that the prior austenite grain size has a significant effect on bainitic variant selection, which governed the effective grain size and crack propagation mechanism. CP (close-packed plane) grouping of variants is more likely to take place in large austenite grain, indicating that the size of CP region is larger than Bain zone, and the crack is short and flexural. On the contrary, in smaller austenite grain, Bain grouping of variants that always forms low angle grain boundary and favors crack propagation dominates the transformation, and it will promote the crack to propagate through the entire Bain zone and then yield large long crack. However, these two cases can co-exist in the same sample at medium cooling rate, indicating that the cleavage fracture is controlled by the effective grain size (Bain-zone size) and the scatter in impact toughness is associated much to the proportion and relative location between fine and coarse Bain zones.