We presented attenuation characteristics of S waves in the crust of Ordos massif. Using 487 pieces of digital oscil- lograms of 19 seismic events recorded by 32 seismologic stations located on Ordos massif and its sur...We presented attenuation characteristics of S waves in the crust of Ordos massif. Using 487 pieces of digital oscil- lograms of 19 seismic events recorded by 32 seismologic stations located on Ordos massif and its surroundings, we have calculated the parameter of three-segment geometric attenuation and give the relation of inelastic attenuation Q value with frequency in the crust of Ordos massif, site responses of 32 stations, and source parameters of 19 events by the genetic algorithm. The results indicate that Q value (at 1 Hz) of S-wave in the crust of Ordos massif is much larger than that in the geologically active tectonic region. The site responses of the 32 stations in the high-frequency section do not show clear amplification effect except one or two stations, while in the low-frequency section, there is difference among the stations. The logarithmic value of seismic moment and the magnitude ML of 19 seismic events has a very good linear relationship.展开更多
Free space optical （FSO） communication has been considered as an alternative to radio relay link line-of- sight （LOS） communication systems. The total attenuation is a combination of atmospheric attenuation in the...Free space optical （FSO） communication has been considered as an alternative to radio relay link line-of- sight （LOS） communication systems. The total attenuation is a combination of atmospheric attenuation in the atmosphere and geometric losses. The purpose of this paper is to study the geometric loss versus link range （in kin）, divergence angle, transmitter aperture diameter, and receiver aperture diameter. Total attenuation versus low visibility, average visibility, beam divergence, link range and rainfall rate were presented in this paper. Atmospheric attenuation （in dB） and scattering coefficient （in km-~） for several Yemeni main cities were explored. The study was concentrated on received power versus low and average visibilities and link range. Series of related simulation results were illustrated and discussed in this paper about the climate effects on performance of FSO communication systems in Yemen.展开更多
基金National Scientific Research Target Project of China (2004BA601B01-04-03) during the tenth Five-year Plan, Joint Seismological Science Foundation of China (104047) and the Application Lab of Digital Seismic Wave Data in Center for Analysis and Prediction.
文摘We presented attenuation characteristics of S waves in the crust of Ordos massif. Using 487 pieces of digital oscil- lograms of 19 seismic events recorded by 32 seismologic stations located on Ordos massif and its surroundings, we have calculated the parameter of three-segment geometric attenuation and give the relation of inelastic attenuation Q value with frequency in the crust of Ordos massif, site responses of 32 stations, and source parameters of 19 events by the genetic algorithm. The results indicate that Q value (at 1 Hz) of S-wave in the crust of Ordos massif is much larger than that in the geologically active tectonic region. The site responses of the 32 stations in the high-frequency section do not show clear amplification effect except one or two stations, while in the low-frequency section, there is difference among the stations. The logarithmic value of seismic moment and the magnitude ML of 19 seismic events has a very good linear relationship.
文摘Free space optical （FSO） communication has been considered as an alternative to radio relay link line-of- sight （LOS） communication systems. The total attenuation is a combination of atmospheric attenuation in the atmosphere and geometric losses. The purpose of this paper is to study the geometric loss versus link range （in kin）, divergence angle, transmitter aperture diameter, and receiver aperture diameter. Total attenuation versus low visibility, average visibility, beam divergence, link range and rainfall rate were presented in this paper. Atmospheric attenuation （in dB） and scattering coefficient （in km-~） for several Yemeni main cities were explored. The study was concentrated on received power versus low and average visibilities and link range. Series of related simulation results were illustrated and discussed in this paper about the climate effects on performance of FSO communication systems in Yemen.
