112 research outputs found

    Seismic response analysis of underground cavern groups of Xiluodu hydraulic power plant

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    The seismic response analysis of underground cavern groups of Xiluodu hydraulic power plant have been investigated by commercial codes in geotechnical engineering FLAC, which is used as the analysis tool to study the diffraction of P wave by the circular hole and the feasibility of the explicit finite difference method to analyze the diffraction in the solid medium is verified. Numerical model in two dimensions of underground cavern groups of Xiluodu hydraulic power plant is generated and the seismic response of underground cavern groups is investigated. Maximum and minimum principal stress amplitude and displacement vectors amplitude of surrounding rock mass gained by the numerical analysis is obtained, which show there is no tensile damage when the underground cavern groups are subjected to the Tangshan aftershock, the displacement of underground openings is not very large, and the surrounding rock still behaves elastically. The results from the analysis can be for reference to similar hydraulic power plant design and construction

    First-principles study of vibrational and dielectric properties of {\beta}-Si3N4

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    First-principles calculations have been conducted to study the structural, vibrational and dielectric properties of {\beta}-Si3N4. Calculations of the zone-center optical-mode frequencies (including LO-TO splittings), Born effective charge tensors for each atom, dielectric constants, using density functional perturbation theory, are reported. The fully relaxed structural parameters are found to be in good agreement with experimental data. All optic modes are identified and agreement of theory with experiment is excellent. The static dielectric tensor is decomposed into contributions arising from individual infrared-active phonon modes. It is found that high-frequency modes mainly contribute to the lattice dielectric constant.Comment: 15pages, 1 figure, 5 table

    Monitoring and analysis of blasting vibration in tunnel excavation of nuclear power plant

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    Vibration monitoring of blasting excavation of drainage tunnel in Lufeng Nuclear Power Plant is carried out and the data of blasting vibration is analyzed in this paper. The results show that: (1) The vertical vibration velocity of the rock mass is greater than the horizontal radial and horizontal tangential vibration velocity (2) The blasting vibration velocity of rock mass decreases with distance, which is affected by rock structure and explosive quantity. The monitoring research in this paper has guiding significance for vibration prediction and control in tunnel blasting excavation

    Adsorbate and defect effects on electronic and transport properties of gold nanotubes

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    First-principles calculations have been performed to study the effects of adsorbates (CO molecules and O atoms) and defects on electronic structures and transport properties of Au nanotubes (Au(5, 3) and Au(5, 5)). For CO adsorption, various adsorption sites of CO on the Au tubes were considered. The vibrational frequency of the CO molecule was found to be very different for two nearly degenerate stable adsorption configurations of Au(5, 3), implying the possibility of distinguishing these two configurations via measuring the vibrational frequency of CO in experiments. After CO adsorption, the conductance of Au(5, 3) decreases by 0.9G0 and the conductance of Au(5, 5) decreases by approximately 0.5G0. For O-adsorbed Au tubes, O atoms strongly interact with Au tubes, leading to around 2G0 of drop in conductance for both Au tubes. These results may have implications for Au-tube-based chemical sensing. When a monovacancy defect is present, we found that, for both tubes, the conductance decreases by around 1G0. Another type of defect arising from the adhesion of one Au atom is also considered. For this case, it is found that, for the Au(5, 3) tube, the defect decreases the conductance by nearly 1G0, whereas for Au(5, 5), the decrease in conductance is only 0.3G0.Comment: 7 pages, 8 figure

    Analysis on monitoring and controlling techniques about blasting vibration effect of open channel in Taishan nuclear power station

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    The blasting for bedrock excavation on land for open channel project has a great influence on lock gate in Taishan Nuclear Power Station, therefore, based on blasting vibration monitoring data, the attenuation law of blasting vibration signal has been studied through regression analysis of practical test data by Sadaovsk empirical formula and corresponding time-frequency characteristics was analyzed by Empirical Mode Decomposition based on Hilbert-Huang transform. As for those monitoring data, the results of blast vibration velocity for vertical direction are generally larger than horizontal radial and horizontal tangential direction in the near field of blasting source and the peak particle velocity of vertical direction is usually lower than horizontal radial and horizontal tangential direction in the far field of blasting source; at the same time, their main vibration frequency mostly vary from 10 Hz to 80 Hz which is much higher than natural frequency of lock gate and is beneficial to structural safety and stability of surrounding rock mass for reducing the probability of resonance. To ensure the safety of lock gate, it is of great significance to control maximum explosive weight per delay in advance for different distance from monitoring point to the explosion source according to Safety Regulations for Blasting (GB6722-2014), which shows the excellent effect on blasting damage control of the lock gate and surrounding rock mass. The results from the analysis can be for reference to similar blasting design and blasting construction