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The determination for diffuse scattering model parameters is of critical importance to improve the accuracy of prediction and analysis for millimeter-wave radio propagation. In this paper, a reliable parameterization method with a simplified tuning procedure for a diffuse scattering model is proposed and validated based on measurements and ray-tracing simulations. Typical construction materials are measured from 40 GHz to 50 GHz, and the complex permittivity is estimated by the propagation coefficients match method. The directive model, which can better characterize the scattering patterns of construction materials in this paper, is adopted to calibrate the ray-tracing simulation. Model parameterization is performed and simulated results with the optimal model parameters show distinct accuracy improvement.

In this study, samples were taken of the surface dust of main roads in Xinxiang City, and the concentrations of five heavy metals (Cd, Pb, Cr, Cu and Zn) and fifteen polycyclic aromatic hydrocarbons (PAHs) were determined by inductively coupled plasma mass spectrometry (ICP-MS) and gas chromatography-mass spectrometry (GC-MS), respectively. Meanwhile, the effects of vehicle emissions on the pollution characteristics were investigated. The results showed that the concentrations of heavy metals and PAHs ranged from 2.58 to 1560 mg·kg

The variation of steady burning rate for heterogeneous propellants over a wide range of pressure is studied by experimental methods and theoretical analysis. Two kinds of heterogeneous propellants, GATo-1 CMDB propellant and 86 series composite propellant, are selected. An explanation for two inflection points observed in burning rate–pressure curve is presented. It is concluded that condensed-phase reaction dominates the burning process in the low-pressure region, which presents a low-pressure exponent, whereas heat feedback from the gas phase predominates in the high-pressure region with a high-pressure exponent. In the medium-pressure region, these two factors influence the burning process cooperatively and pressure exponent reduces first and then rises. Results calculated from the model show good agreement with experimental data. Thermal parameters analysis indicate burning rate is more sensitive to thermal conductivity of condensed phase, activation energy of condensed phase, specific heat capacity, ...

40Cr steel substrate was coated with TiAlN/TiN films by multi-arc ion technology. The effect of technical elements on the surface and micro hardness of TiAlN/TiN films had been studied with metallographic microscope, SEM and micro hardness instrument. The results show that the negative bias and the target current have marked influence in performance of TiAlN/TiN films. The content of Ti and Al in films becomes lower and lower when the negative bias becomes higher and higher. The content of Ti/Al of films increases when the target current increases. The micro hardness increases firstly and then drops with the increase of negative bias or the target current.

40Cr steel substrate is coated with TiAlN/TiN films by Multi-arc ion technology. The properties of sliding friction and wear on the surfaces of TiAlN/TiN films and substrate are tested by using the machine of friction and wear. The carrying capacity and tribological properties are investigated. The surface morphology of wear specimens is observed and the elements of wear scar center are analyzed. The results show that the friction coefficient of TiAlN/TiN films is lower than 40Cr under the same conditions. The wear scar of TiAlN/TiN films is lower and the wear loss is fewer than 40Cr. The TiAlN/TiN films can successfully reduce friction and wear resistance.

The variation of steady burning rate for heterogeneous propellants over a wide range of pressures is studied by experimental methods and theoretical analysis. Two kinds of heterogeneous propellants, GATo-1 composite modified double-base (CMDB) propellant and 86 series composite propellant are selected. An explanation that two inflection points observed in burning rate-pressure curve is presented. It is concluded that condensed phase reaction dominates the burning process in low pressure region which presents a small pressure exponent, while heat feedback from gas phase predominates in high pressure region with a large pressure exponent. In medium pressure region, these two factors influence the burning process cooperatively and pressure exponent exhibits the trend of reducing and then rising. Results calculated from the model show good agreement with experimental data. Thermal parameters analysis indicates that burning rate is more sensitive to the thermal conductivity of condensed phase, activation energy of condensed phase, specific heat capacity and delay time of heat release of condensed phase reaction in high pressures. Insights and guideline of burning rate characteristics in high pressures and interior ballistic properties for solid propellant impulsive microthruster are provided by our model.