摘要 : The evolution of pulsed signals in a quadratically nonlinear medium with a special relaxation law is studied. It is believed that the "memory of the medium" weakens according to a linear law and becomes zero within a finite time. ... 展开 The evolution of pulsed signals in a quadratically nonlinear medium with a special relaxation law is studied. It is believed that the "memory of the medium" weakens according to a linear law and becomes zero within a finite time. Instead of standard integro-differential equations with exponential or fractional power kernels, a model of a medium with a finite memory time is used here. For this model, analysis of complex integro-differential equations reduces to solving a differential-difference equation; at the same time, the amount of calculations is appreciably curtailed. The processes accompanying pulse evolution-shock front formation, nonlinear attenuation, and signal spreading with time-are described. The influence of the relaxation time on these processes is explained. 收起