Firstly, studies on propagation of one-dimensional normally incident wave in rock mass containing no joint, a single joint and two parallel joints were conducted by Three Dimensional Distinct Element Codes(3DEC). By c...Firstly, studies on propagation of one-dimensional normally incident wave in rock mass containing no joint, a single joint and two parallel joints were conducted by Three Dimensional Distinct Element Codes(3DEC). By comparison of the modeling results with the theoretical solutions, it has been found that a good agreement between them has been achieved. It is verified that the 3DEC is capable of modeling wave propagation in rock masses. Secondly, propagation of normally incident P-wave across two parallel joints was studied. The modeling results show that transmission coefficient increases with the increasing ratio of joint spacing to wavelength at first, then decreases with the increasing ratio of joint spacing to wavelength, lastly keeps constant. Finally, effect of interlayer on wave propagation is investigated. It is shown that interlayer results in marked attenuation and leading phase, and that attenuation increases with the increasing frequency and the increasing thickness of interlayer.展开更多
A new digital communication technology based on the Phase-Offset Overlapped Waves (POOW) has been introduced in this letter.The waves can be considered as a special multicarrier different from traditional ones.The sud...A new digital communication technology based on the Phase-Offset Overlapped Waves (POOW) has been introduced in this letter.The waves can be considered as a special multicarrier different from traditional ones.The sud-waves in a coded word's period of the POOW are sine waves and have the same frequencies,but different starting phases.The most important characteristic is that these sub-waves are the piecewise functions and not orthogonal in a code word period.The decoding can be implemented by solving a linear equation group.This code has very high efficiency and thus the data transmissin rate is increased greatly.展开更多
A series solution for surface motion amplification due to underground group cavities for incident plane P waves is derived by Fourier-Bessel series expansion method. It is shown that underground group cavities signifi...A series solution for surface motion amplification due to underground group cavities for incident plane P waves is derived by Fourier-Bessel series expansion method. It is shown that underground group cavities significantly am-plify the surface ground motion nearby. It is suggested that the effect of subways on ground motion should be con-sidered when the subways are planned and designed.展开更多
【正】 A new digital communication technology based on the Phase-Offset OverlappedWaves (POOW) has been introduced in this letter. The waves can be considered as a specialmulticarrier different from traditional ones. ...【正】 A new digital communication technology based on the Phase-Offset OverlappedWaves (POOW) has been introduced in this letter. The waves can be considered as a specialmulticarrier different from traditional ones. The sub-waves in a coded word’s period of thePOOW are sine waves and have the same frequencies, but different starting phases. The mostimportant characteristic is that these sub-waves are the piecewise functions and not orthogonalin a code word period. The decoding can be implemented by solving a linear equation group.展开更多
基金Major projects(50490272, 50490274) supported by the National Natural Science Foundation of China Project (2002CB412703) supported by the National Basic Research Program of China
文摘Firstly, studies on propagation of one-dimensional normally incident wave in rock mass containing no joint, a single joint and two parallel joints were conducted by Three Dimensional Distinct Element Codes(3DEC). By comparison of the modeling results with the theoretical solutions, it has been found that a good agreement between them has been achieved. It is verified that the 3DEC is capable of modeling wave propagation in rock masses. Secondly, propagation of normally incident P-wave across two parallel joints was studied. The modeling results show that transmission coefficient increases with the increasing ratio of joint spacing to wavelength at first, then decreases with the increasing ratio of joint spacing to wavelength, lastly keeps constant. Finally, effect of interlayer on wave propagation is investigated. It is shown that interlayer results in marked attenuation and leading phase, and that attenuation increases with the increasing frequency and the increasing thickness of interlayer.
文摘A new digital communication technology based on the Phase-Offset Overlapped Waves (POOW) has been introduced in this letter.The waves can be considered as a special multicarrier different from traditional ones.The sud-waves in a coded word's period of the POOW are sine waves and have the same frequencies,but different starting phases.The most important characteristic is that these sub-waves are the piecewise functions and not orthogonal in a code word period.The decoding can be implemented by solving a linear equation group.This code has very high efficiency and thus the data transmissin rate is increased greatly.
基金Supported by National Natural Science Foundation of China (50378063), Excellent Young Teachers Program of MOE and SRF for ROCS, MOE.
文摘A series solution for surface motion amplification due to underground group cavities for incident plane P waves is derived by Fourier-Bessel series expansion method. It is shown that underground group cavities significantly am-plify the surface ground motion nearby. It is suggested that the effect of subways on ground motion should be con-sidered when the subways are planned and designed.
文摘【正】 A new digital communication technology based on the Phase-Offset OverlappedWaves (POOW) has been introduced in this letter. The waves can be considered as a specialmulticarrier different from traditional ones. The sub-waves in a coded word’s period of thePOOW are sine waves and have the same frequencies, but different starting phases. The mostimportant characteristic is that these sub-waves are the piecewise functions and not orthogonalin a code word period. The decoding can be implemented by solving a linear equation group.
