The article analyzes the classical BM algorithm and an improved algorithm, and then it puts forward a new improved algorithm which called I_BM algorithm according to the characteristics of the string matching. The I_B...The article analyzes the classical BM algorithm and an improved algorithm, and then it puts forward a new improved algorithm which called I_BM algorithm according to the characteristics of the string matching. The I_BM algorithm determines the right distance according to the first character of the pattern string and the distance between the matching windows, so it fasts matching. The matching way of I_BM algorithm is from right to left. In order to verify the IBM algorithm＇ s performance, it does experiments on I_BM algorithm from two aspects of the matching times and the numbers of matching characters under the condition of the same text strings and pattem string. The experimental results show that I_BM algorithm is more quickly and more efficient because it reduces greatly the number of matching and character comparison for maximizing to skip the bad characters.展开更多
Based on the Marshall-Palmer,Weibull raindrop size distribution and Mie electromagnetic scattering model,the relationships of attenuation coefficient of terahertz(THz) atmospheric window waves with precipitation rate ...Based on the Marshall-Palmer,Weibull raindrop size distribution and Mie electromagnetic scattering model,the relationships of attenuation coefficient of terahertz(THz) atmospheric window waves with precipitation rate and temperature are studied.Furthermore,combined with the loss of electromagnetic wave transmission in free space,the attenuation of THz communication and the transmission of current mobile communication signals through rain are compared and analyzed.The results show that the attenuation coefficient of THz transmission is increased with increasing precipitation rate,the difference of attenuation coefficient at different THz window waves is small,and the maximum difference is about 3 dB.The rain attenuation of THz wave is first decreased and then increased with increasing temperature,but the temperature has little effect on it.The attenuation of THz wave through rain is much larger than that of mobile communication signal.展开更多
文摘The article analyzes the classical BM algorithm and an improved algorithm, and then it puts forward a new improved algorithm which called I_BM algorithm according to the characteristics of the string matching. The I_BM algorithm determines the right distance according to the first character of the pattern string and the distance between the matching windows, so it fasts matching. The matching way of I_BM algorithm is from right to left. In order to verify the IBM algorithm＇ s performance, it does experiments on I_BM algorithm from two aspects of the matching times and the numbers of matching characters under the condition of the same text strings and pattem string. The experimental results show that I_BM algorithm is more quickly and more efficient because it reduces greatly the number of matching and character comparison for maximizing to skip the bad characters.
文摘Based on the Marshall-Palmer,Weibull raindrop size distribution and Mie electromagnetic scattering model,the relationships of attenuation coefficient of terahertz(THz) atmospheric window waves with precipitation rate and temperature are studied.Furthermore,combined with the loss of electromagnetic wave transmission in free space,the attenuation of THz communication and the transmission of current mobile communication signals through rain are compared and analyzed.The results show that the attenuation coefficient of THz transmission is increased with increasing precipitation rate,the difference of attenuation coefficient at different THz window waves is small,and the maximum difference is about 3 dB.The rain attenuation of THz wave is first decreased and then increased with increasing temperature,but the temperature has little effect on it.The attenuation of THz wave through rain is much larger than that of mobile communication signal.
