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The Precise Point Positioning-Real Time Kinematic (PPP-RTK) technique, which provides centimeter-level positioning with instantaneous ambiguity resolution, is considered as a potential tool for intelligent vehicle applications. However, its performance is restricted under complex urban conditions owing to intermittent signal interruptions and poor satellite geometries. Thus, a tightly coupled Multi-Frequency (MF) PPP-RTK/INS (Inertial Navigation System) model was developed with the objective of providing a stable and reliable positioning for the urban vehicle. In this model, the augmentation of INS information, third-frequency observations, precise atmospheric corrections, the fixed Extra-Wide Lane (EWL), and Wide-Lane (WL) ambiguities can be used to enhance the positioning performance of PPP-RTK. We designed urban vehicle experiments under different scenarios to validate the proposed method. The results show that PPP-RTK can be significantly improved for urban vehicle positioning by fusing the MF and INS. In urban areas, the solution availability with a horizontal positioning error within 10 cm was 96.1% for MFPPP-RTK/INS with a fixing percentage of 90.9%. Compared with the dual-frequency PPP-RTK solutions, the fixing percentage and solution availability in the MFPPP-RTK/INS was improved by 9.5% and 8.8%, respectively. Moreover, MFPPP-RTK/INS provides continuous and stable positioning and fast ambiguity recovery in GNSS-challenged environments. The MFPPP-RTK/INS could achieve a fast ambiguity re-fixing within 1 s after continuously crossing obstacles, whereas PPP-RTK could achieve the same in 10 s. [ABSTRACT FROM AUTHOR]

The manipulation of electromagnetic waves using metasurfaces is important in areas such as stealth and communication. In this paper, we reported on the use of an element-based polarizer for the first step, which enables the incident electromagnetic waves to integrate into the cross-polarized waves with a relative bandwidth of 88% within 15–37.1 GHz. Then, an eight-element coding metasurface based on the Pancharatnam–Berry phase is presented for circular polarization anomalous reflection. The simulated values show that our work can achieve a high-efficiency (94%) and wide-angle (70°) anomalous reflection under normal incidence. The simulated values present good agreement with the experimental values. Our work reveals the ability to manipulate the waves and electromagnetic stealth. [ABSTRACT FROM AUTHOR]

In order to study the influencing factors of crushing efficiency of coal containing gas under submerged jet, the influence of different water jet impact conditions on coal crushing efficiency was studied, and the fluid solid coupling model of water jet crushing coal containing gas was established. Taking coal crushing depth and coal crushing volume as indexes, the effects of jet angle, jet velocity, nozzle diameter and initial target distance on coal crushing efficiency were investigated. The results show that: under the condition of submerged jet, bullet shaped crushing pit is formed in the initial stage of jet coal breaking process. With the process of coal breaking, the diameter of crushing pit increases and the depth extends downward; under the condition of submerged jet, the depth and volume of coal breaking are positively correlated with the change of jet velocity and nozzle diameter, and negatively correlated with the change of initial target distance, the depth of broken coal pit reaches the maximum value when the jet is perpendicular to the coal, and the broken coal volume increases first, then decreases and then rises with the increase of jet angle, reaching the maximum value at 90°; based on the orthogonal experiment, the primary and secondary order of theinfluence of different jet parameters on the coal breaking efficiency of submerged jet is as follows: jet inclination angle, jet velocity, nozzle diameter and initial target distance.

Abstract: Highly dispersed of nanosized TiO2 inside mesoporous silica was reported for the first time by using a sonochemical approach. The amount of TiO2 inside the pores of SBA-15 has been controlled through the irradiation time. Characterizations by powder X-ray diffraction, nitrogen adsorption–desoprtion, X-ray photoelectron spectra (XPS), UV–vis spectroscopy and Fourier transform infrared (FT-IR) spectra have been carried out to understand the nature of TiO2 formed inside the pores. At low titania loading of 7–18.5wt.%, TiO2 is monoatomically dispersed and the pore size of SBA-15 is not altered. With higher titania loading (28wt.%), the incorporation of TiO2 inside the mesopores of SBA-15 results in a slight reduction of the pore size without blocking the pores. The photocatalytic activities of the resultant nanocomposites with titania loading of 28wt.% were assessed by measuring the percentage degradation of methyl blue (MB) using UV–vis spectroscopy. The results indicate the sample exhibits an improved photocatalytic performance together with a high adsorption capability as compared with that of the commercial P25. This facile strategy may be extended to other metal oxides, with potential high performance in many applications. [Copyright &y& Elsevier]