The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer （PDA）. Laden with very large particles, no significant atten...The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer （PDA）. Laden with very large particles, no significant attenuations of turbulence intensities were measured in the farfields, due to small two-phase slip velocities and particle Reynolds number. The gas-phase turbulence is enhanced by particles in the near-fields, but it is significantly attenuated by the small particles in the far-fields. The smaller particles have a more profound effect on the attenuation of turbulence intensities. The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production, transport and dissipation mechanisms between the two phases, which are determined by the particle prop- erties and two-phase velocity slips. The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity.展开更多
Optics surface phase defects induced intensity modulation in high-power laser facility for inertial confinement fusion research is studied. Calculations and experiments reveal an exact mapping of the modulation patter...Optics surface phase defects induced intensity modulation in high-power laser facility for inertial confinement fusion research is studied. Calculations and experiments reveal an exact mapping of the modulation patterns and the optics damage spot distributions from the surface phase defects. Origins are discussed during the processes of optics manufacturing and diagnostics, revealing potential improvements for future optics manufacturing techniques and diagnostic index, which is meaningful for fusion level laser facility construction and its operation safety.展开更多
We present how residual intensity modulation(RIM) affects the performance of a resonator fiber optic gyro(R-FOG) through a sinusoidal wave phase modulation technique. The expression for the R-FOG system's demodula...We present how residual intensity modulation(RIM) affects the performance of a resonator fiber optic gyro(R-FOG) through a sinusoidal wave phase modulation technique. The expression for the R-FOG system's demodulation curve under RIM is obtained. Through numerical simulation with different RIM coefficients and modulation frequencies, we find that a zero deviation is induced by the RIM effect on the demodulation curve, and this zero deviation varies with the RIM coefficient and modulation frequency. The expression for the system error due to this zero deviation is derived. Simulation results show that the RIM-induced error varies with the RIM coefficient and modulation frequency. There also exists optimum values for the RIM coefficient and modulation frequency to totally eliminate the RIM-induced error, and the error increases as the RIM coefficient or modulation frequency deviates from its optimum value; however, in practical situations, these two parameters would not be exactly fixed but fluctuate from their respective optimum values, and a large system error is induced even if there exists a very small deviation of these two critical parameters from their optimum values. Simulation results indicate that the RIM-induced error should be considered when designing and evaluating an R-FOG system.展开更多
随着云业务、视频业务和移动互联业务的快速发展,5G光接入网对于传输容量的需求日益迫切。接入网段日益增长的带宽需求不仅要求更高的传输速度,还需要保持较低的系统成本。但是成熟的商用低成本光电器件的带宽通常是有限的,当传输速率...随着云业务、视频业务和移动互联业务的快速发展,5G光接入网对于传输容量的需求日益迫切。接入网段日益增长的带宽需求不仅要求更高的传输速度,还需要保持较低的系统成本。但是成熟的商用低成本光电器件的带宽通常是有限的,当传输速率很高时,带宽明显小于信号的波特率。考虑到低成本光学器件的有限带宽,采用具有高频谱效率的先进调制格式,如PAM,CAP以及DMT是很有潜力的选择。主要针对光接入网器件带宽受限的问题,在带宽受限的100 G无源光网络中,仿真对比了三种先进调制格式的性能,分析了三种调制格式传输20 km SSMF后的接收灵敏度和功率预算,还讨论了他们的热噪声性能和抗色散性能。展开更多
基金supported by the National Natural Science Foundation of China (50876053 and 50706021).
文摘The particle modulations to turbulence in round jets were experimentally studied by means of two-phase velocity measurements with Phase Doppler Anemometer （PDA）. Laden with very large particles, no significant attenuations of turbulence intensities were measured in the farfields, due to small two-phase slip velocities and particle Reynolds number. The gas-phase turbulence is enhanced by particles in the near-fields, but it is significantly attenuated by the small particles in the far-fields. The smaller particles have a more profound effect on the attenuation of turbulence intensities. The enhancements or attenuations of turbulence intensities in the far-fields depends on the energy production, transport and dissipation mechanisms between the two phases, which are determined by the particle prop- erties and two-phase velocity slips. The non-dimensional parameter CTI is introduced to represent the change of turbulence intensity.
基金supported by the SG-Ⅲ laser facility upgrade project
文摘Optics surface phase defects induced intensity modulation in high-power laser facility for inertial confinement fusion research is studied. Calculations and experiments reveal an exact mapping of the modulation patterns and the optics damage spot distributions from the surface phase defects. Origins are discussed during the processes of optics manufacturing and diagnostics, revealing potential improvements for future optics manufacturing techniques and diagnostic index, which is meaningful for fusion level laser facility construction and its operation safety.
基金Project supported by the Zhejiang Provincial Natural ScienceFoundation of China(No.LQ13F050001)
文摘We present how residual intensity modulation(RIM) affects the performance of a resonator fiber optic gyro(R-FOG) through a sinusoidal wave phase modulation technique. The expression for the R-FOG system's demodulation curve under RIM is obtained. Through numerical simulation with different RIM coefficients and modulation frequencies, we find that a zero deviation is induced by the RIM effect on the demodulation curve, and this zero deviation varies with the RIM coefficient and modulation frequency. The expression for the system error due to this zero deviation is derived. Simulation results show that the RIM-induced error varies with the RIM coefficient and modulation frequency. There also exists optimum values for the RIM coefficient and modulation frequency to totally eliminate the RIM-induced error, and the error increases as the RIM coefficient or modulation frequency deviates from its optimum value; however, in practical situations, these two parameters would not be exactly fixed but fluctuate from their respective optimum values, and a large system error is induced even if there exists a very small deviation of these two critical parameters from their optimum values. Simulation results indicate that the RIM-induced error should be considered when designing and evaluating an R-FOG system.
文摘随着云业务、视频业务和移动互联业务的快速发展,5G光接入网对于传输容量的需求日益迫切。接入网段日益增长的带宽需求不仅要求更高的传输速度,还需要保持较低的系统成本。但是成熟的商用低成本光电器件的带宽通常是有限的,当传输速率很高时,带宽明显小于信号的波特率。考虑到低成本光学器件的有限带宽,采用具有高频谱效率的先进调制格式,如PAM,CAP以及DMT是很有潜力的选择。主要针对光接入网器件带宽受限的问题,在带宽受限的100 G无源光网络中,仿真对比了三种先进调制格式的性能,分析了三种调制格式传输20 km SSMF后的接收灵敏度和功率预算,还讨论了他们的热噪声性能和抗色散性能。
