Search

Your search keyword '"Wu, Zhi‐Qiang"' showing total 470 results
Start Over Author "Wu, Zhi‐Qiang"
470 results on '"Wu, Zhi‐Qiang"'

168. Propagation characteristics of seismic waves in shallow soil with the unsaturated three-phase poroelastic model

Author

Wang Chi, Ding Wei, Wu Wen-Wen, and Wu Zhi-Qiang

Subjects
Three-phase, Poromechanics, General Physics and Astronomy, Geology, Seismology, Seismic wave, Physics::Geophysics
Abstract

In order to study the mechanism of acoustic landmine detection, the propagation characteristics of acoustically coupled seismic waves in shallow soil are investigated. Based on the porosity and compressibility of shallow soil, the influences of parameters including soil porosity and water saturation on the propagation properties of seismic wave are discussed with the model of seismic waves in unsaturated three-phase porous medium. The calculation results show that under the given parameters, the propagation velocity and attenuation coefficient of seismic wave increase with the increase of acoustic frequency. The propagation velocities of longitudinal waves and those of transverse waves respectively decrease and increase with the increase of soil porosity. In addition, the propagation characteristics of acoustically coupled seismic waves become complicated with the increase of water saturation. The feasibility of the analysis method is discussed by comparing the calculation results with the experimental data published previously. As a result, a theoretical foundation is provided for the acoustic-to-seismic coupling mechanism and its application in the study of acoustic resonance landmine detection.

Published
2014

182. Suppressing the preferential σ-polarization oscillation in a high power Nd:YVO4laser with wedge laser crystal

Author

Wu Zhi-Qiang, Zheng Yao-Hui, Wang Ya-Jun, and Zhou Hai-Jun

Subjects
Active laser medium, Materials science, business.industry, Slope efficiency, Physics::Optics, General Physics and Astronomy, Ring laser, Polarization (waves), Laser, Gain-switching, law.invention, Optics, law, Laser power scaling, business, Lasing threshold
Abstract

We observe the phenomenon of priority oscillation of the unexpected σ-polarization in high-power Nd:YVO4 ring laser. The severe thermal lens of the σ-polarized lasing, compared with the π-polarized lasing, is the only reason for the phenomenon. By designing a wedge Nd:YVO4 crystal as the gain medium, the unexpected σ-polarization is completely suppressed in the entire range of pump powers, and the polarization stability of the expected π-polarized output is enhanced. With the output power increasing from threshold to the maximum power, no σ-polarization lasing is observed. As a result, 25.3 W of stable single-frequency laser output at 532 nm is experimentally demonstrated.

Published
2013

183. Band gap design for one-dimensional periodic structure with three oscillators

Author

Wu Zhi-Qiang and Gao Ming

Subjects
Physics, Band gap, business.industry, Singularity theory, Mathematical analysis, Structure (category theory), General Physics and Astronomy, Stiffness, Dispersion (optics), medicine, medicine.symptom, Photonics, business, Topology (chemistry), Dimensionless quantity
Abstract

Dimensionless dispersion curve equation of one-dimensional periodic structure with three oscillators is deduced. It is proved by singularity theory that the topology of the dispersion curves does not change with mass and stiffness parameter. Then the equations of initial and final frequencies of the bands are presented. The method of band gap design is gained consequently. Two examples i.e., the system with the same stiffness and the system with the same mass, are given to verify it. The method may provide the reference for designing the band gap of the photonic and phononic crystals.

Published
2013

192. Positive effects of treatment of donor cells with aphidicolin on the preimplantation development of somatic cell nuclear transfer embryos in Chinese Bama mini-pig (Sus Scrofa)

Author

ZHANG, Ting-Yu, primary, DAI, Jian-Jun, additional, WU, Cai-Feng, additional, GU, Xiao-Long, additional, LIU, Liang, additional, WU, Zhi-Qiang, additional, XIE, Yi- Ni, additional, WU, Bin, additional, CHEN, Hui-Lan, additional, LI, Yao, additional, CHEN, Xue-Jin, additional, and ZHANG, De-Fu, additional

Published
2011
Full Text
View/download PDF

197. Constrained bifurcations of the system with double-loop bilinear hysteresis

Author

Zhang Zhen-Hua, Wu Zhi-Qiang, and Hao Ying

Subjects
Frequency response, Hysteresis, Amplitude, Control theory, Mathematical analysis, General Physics and Astronomy, Bilinear interpolation, Shape-memory alloy, Parameter space, Bifurcation, Damper, Mathematics
Abstract

Systems with double-loop hysteresis are used increasingly in engineering, but few studies on their dynamics are reported. In this study, the bifurcation characteristics of the primary resonance of a system with double-loop bilinear hysteresis are investigated on the background of a shape memory alloy damper. First, the frequency-amplitude response equation is obtained by using the averaging methods. Then, the influences of the temperature and the amplitude of excitation on amplitude-frequency responses are analyzed by the constrained bifurcation singularity analysis method of non-smooth systems. The calculation results show that the parameter space composed of the temperature and the amplitude of excitation can be divided into 11 regions, which suggest that there are 11 qualitatively different kinds of amplitude-frequency responses to the variation of two parameters. In order to describe and compare the frequency-amplitude response curves conveniently, an encoding rule is proposed to describe their jump phenomena as the frequency sweeps. The above results can guide directly the design of frequency response mode of the system.

Published
2011

Catalog

Books, media, physical & digital resources
See catalog results