The variational principle states that if a differentiable functional F attains its minimum at some point zi, then F’(C) = 0; it has proved a valuable tool for studying partial differential equations. This paper shows that if a differentiable function F has a finite lower bound (although it need not attain it), then, for every E > 0, there exists some point u( where 11 F’(uJj* < l , i.e., its de...

In this study, a dynamic Mindlin–Reissner-type plate is developed based on simplified version of Mindlin’s form-II first-strain gradient elasticity theory. The governing equations motion and the corresponding boundary conditions are derived using general virtual work variational principle. presented model contains, apart from two classical Lame constants, one additional microstructure material ...

We establish the variational principle of Kolmogorov-PetrovskyPiskunov (KPP) front speeds in temporally random shear flows inside an infinite cylinder, under suitable assumptions of the shear field. A key quantity in the variational principle is the almost sure Lyapunov exponent of a heat operator with random potential. The variational principle then allows us to bound and compute the front spe...