In order to study the influence of tunnel blasting free face number on ground vibration velocity, based on the blasting construction of the Tunnel Boring Mechine (TBM) double-conducting tunnel with a large cross section in the section between Guizhou Road Station and Xizhen Station of Qingdao Metro Line 1. The ANSYS/LS-DYNA finite element program was used to carry out numerical simulation research on tunnel blasting under single, two and three free face conditions. By extracting the ground nodes vibration velocity and the blasting center distance, the calculation formula of blasting vibration velocity under the condition of different number of free faces is obtained by fitting regression. Studies have shown that (1) the values of K and gradually decrease with the increase of the free face, and the decay rate of the K is more significant. In the process of increasing the number of free faces from 1 to 3, the decreasing rate of K was 61.56% and 80.4%, and the decreasing rate of was 8.49% and 30.16%, respectively. (2) Tunnel blasting vibration is affected by the number of free faces. Under the condition of equal charge of 1.2kg, the decay rate of the overall vibration velocity of blasting under the condition of a single free face to the vibration velocity of two or three free faces is 26.12% , 34.85%, the vibration velocity shows a non-linear decreasing trend with the increase of the number of free faces.
A diode-pumped, passively Q-switched, intracavity-frequency-doubled YVO4/Nd:YVO4/KTP green laser has been realized with a monolayer graphene as the saturable absorber. Under an incident pump power of 10.5 W, the maximum output power of the passively Q-switched green laser was 516 mW with a repetition rate of 222 kHz and pulse width of 202 ns. The corresponding pulse energy and the peak power were 2.32 μJ and 11.5 W, respectively.
SiO2 films have been widely applied in the production of electronic devices, integrated devices, optical thin film devices,
sensors because of their desirable properties, such as good insulation, high light transmittance, strong corrosion
resistance, good dielectric properties, etc. Amorphous silicon dioxide was fabricated by plasma enhanced chemical
deposition on GaAs substrate. The thickness and refractive index are obtained by optical transmittance of the film,
which are measured by ellipsometer. The deposition rate of the film and the refractive index are studied at different time,
pressure, and the ratio of SiH4/N2O. The SiO2 thin film growth rate remained basically unchanged versus time. The
reaction chamber pressure, which make the SiO2 thin film growth rate getting the peak, should be about 105Pa. But the
SiO2 thin film growth rate and the refractive index are anti-related. The enormous changes of the gas flow rate do not
have huge impact to the response rate. However, the refractive index of SiO2 thin film changed greatly when the SiH4flow increased the refractive index of the thin films is highest when the ratio of SiH4/N2O is 200:20
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