This paper exploits the Rayleigh integral method to simulate the propagation of transmitted ultrasonic waves and received echoes through various media. Performed simulations study the effect of apodization using diffe...This paper exploits the Rayleigh integral method to simulate the propagation of transmitted ultrasonic waves and received echoes through various media. Performed simulations study the effect of apodization using different types of windows and the effect of medium properties on the reflections obtained. All estimations are done using the Rayleigh integral method simplified by the Fresnel approximation. Five different interfaces are considered： tissue-bone-tissue, tissue-fat-bone, fat-muscle-bone, air-fat-bone and water-fat-bone. The apodization simulations show that the hamming window is more efficient than the rectangular and triangular windows for obtaining a more consistent beam. In the second set of simulations, reflections are mapped with respect to the depth from which these reflections are generated. It demonstrates that the solid and water media allow for the attainment of echoes from deeper regions as compared to the air medium. Matlab is used as the simulation framework.展开更多
This paper presents an acoustic design sensitivity(ADS)analysis on sound radiation of structures by using the boundary element method(BEM).We calculated the velocity distribution of the thin plate by analytical method...This paper presents an acoustic design sensitivity(ADS)analysis on sound radiation of structures by using the boundary element method(BEM).We calculated the velocity distribution of the thin plate by analytical method and the surface sound pressure by Rayleigh integral,and expressed the sound radiation power of the structure in a positive definite quadratic form of the Hermitian with an impedance matrix.The ADS analysis of the plate was thus translated into the analysis of structure dynamic sensitivity and ...展开更多
The spectral purity of fiber lasers has become a critical issue in both optical sensing and communication fields.As a result of ultra-narrow intrinsic linewidth, stimulated thermal Rayleigh scattering(STRS) has presen...The spectral purity of fiber lasers has become a critical issue in both optical sensing and communication fields.As a result of ultra-narrow intrinsic linewidth, stimulated thermal Rayleigh scattering(STRS) has presented special potential to compress the linewidth of fiber lasers. To suppress stimulated Brillouin scattering(SBS), the most dominant disturbance for STRS in optical fibers, a semi-quantitative estimation has been established to illuminate the mechanism of suppressing SBS in a periodic tapered fiber, and it agrees with experimental results. Finally, a linewidth compression device based on STRS is integrated into a single-longitudinal-mode ring-cavity fiber laser with secondary cavities, and its linewidth is verified to be 200 Hz through a self-heterodyne detecting and Voigt fitting method.展开更多
文摘This paper exploits the Rayleigh integral method to simulate the propagation of transmitted ultrasonic waves and received echoes through various media. Performed simulations study the effect of apodization using different types of windows and the effect of medium properties on the reflections obtained. All estimations are done using the Rayleigh integral method simplified by the Fresnel approximation. Five different interfaces are considered： tissue-bone-tissue, tissue-fat-bone, fat-muscle-bone, air-fat-bone and water-fat-bone. The apodization simulations show that the hamming window is more efficient than the rectangular and triangular windows for obtaining a more consistent beam. In the second set of simulations, reflections are mapped with respect to the depth from which these reflections are generated. It demonstrates that the solid and water media allow for the attainment of echoes from deeper regions as compared to the air medium. Matlab is used as the simulation framework.
基金Funded by Doctoral Program Foundation of Institutions of Higher Education of China(20070487403)Natural Science Foundation of Hubei Province of China(2006ABA71)
文摘This paper presents an acoustic design sensitivity(ADS)analysis on sound radiation of structures by using the boundary element method(BEM).We calculated the velocity distribution of the thin plate by analytical method and the surface sound pressure by Rayleigh integral,and expressed the sound radiation power of the structure in a positive definite quadratic form of the Hermitian with an impedance matrix.The ADS analysis of the plate was thus translated into the analysis of structure dynamic sensitivity and ...
基金National Natural Science Foundation of China(NSFC)(51575140,61377084)Science Fund for Distinguished Young Scholars of Harbin(RC2016JQ006007)
文摘The spectral purity of fiber lasers has become a critical issue in both optical sensing and communication fields.As a result of ultra-narrow intrinsic linewidth, stimulated thermal Rayleigh scattering(STRS) has presented special potential to compress the linewidth of fiber lasers. To suppress stimulated Brillouin scattering(SBS), the most dominant disturbance for STRS in optical fibers, a semi-quantitative estimation has been established to illuminate the mechanism of suppressing SBS in a periodic tapered fiber, and it agrees with experimental results. Finally, a linewidth compression device based on STRS is integrated into a single-longitudinal-mode ring-cavity fiber laser with secondary cavities, and its linewidth is verified to be 200 Hz through a self-heterodyne detecting and Voigt fitting method.
