الفهرس 
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Abstract
Using the extended Poincaré-Lighthill-Kue (PLK) method, the oblique collision of two dust acoustic solitons (DASs) in a magnetized non-extensive plasma including the effect of dust pressure anisotropy is studied. The dust fluid is supposed to have an arbitrary charge. A couple of Korteweg-de Vries (KdV) equations are derived for the colliding DASs. The phase shift of each wave is obtained. It is found that the dust pressure anisotropy, the non-extensive parameters for electrons (qe) and ions (qi) play an important role in determining the wave phase shifts after the collision. The present results show that, for negative dust case, the phase shift of the first soliton decreases while the phase shift of the second one increases as either the dust pressure ratio (Pr) increases or qi decreases. Moreover, for positive dust case, the phase shift of the first soliton decreases while the phase shift of the second one increases as either Pr or qi increases. The application of the present findings to some dusty plasma phenomena observed in space and laboratory plasmas is briefly discussed. On the other side, the head-on collision of two, four and six dust ion acoustic solitons (DIASs) in an unmagnetized non-extensive plasma is studied. The dispersion characteristics are analyzed. Using the extended PLK method, two different KdV equations are derived for the colliding DIASs. The Hirota`s direct bilinear method is applied to get the multisoliton solutions for the derived KdV equations. Then, the mathematical expressions for the phase shifts due to the head-on collision between two, four and six DIASs are obtained. It is found that the non-extensive parameter for electrons plays a significant role in the collision process in such a way that the amplitude of the solitons increases as the non-extensive parameter increases and the phase shifts of the colliding waves depend clearly on the non-extensive parameter .