Numerical examples illustrated the spatiotemporal properties such as spectrum redshifting , narrowing and pulse distortion , etc . it is stressed that the " antibeam " behavior of ultrashort pulsed beams can be avoided , if a suitable truncation function is introduced to the initial pulse spectrum 數(shù)值計算例說明了在色散介質(zhì)中會出現(xiàn)譜紅移、變窄、及脈沖形變等傳輸效應(yīng),而且對初始光譜引入截斷函數(shù)可以避免“非光束”行為。