We consider a beam-string-beam transmission problem, where two structurally damped or undamped beams are coupled with frictionally string by conditions. show that for this structure, the dissipation produced frictional part is strong enough to produce exponential decay of solution no matter how small its size. For stability in damped-damped-damped situation we use energy method. undamped-damped...

A broad overview of the current status of proton stability in unified models of particle interactions is given which includes non supersymmetric unification, SUSY and SUGRA unified models, unification based on extra dimensions, and string-M-theory models. The extra dimensional unification includes 5D and 6D and universal extra dimensional (UED) models, and models based on warped geometry. Proto...