, and later in other parts of Africa), some questions are raised: were there any religious minorities among early Muslims who came (or were brought) to America; when did early Muslims entered America ? Contact theories were briefly reviewed to show early...

In the present study, free vibration of a vibratory system equipped with an impact damper, which incorporates the Hertzian contact theory, is investigated. A nonlinear model of an impact damper is

constructed using spring, mass, and viscous...