 period temperatur distribut two-layer composit slab period temperatur distribut two-layer composit slab contribut reader's forum titl stonecyph outlin method find period temperatur distribut two-layer composit slab expos surfac slab insul subject sinusoid temperatur variat perfect thermal contact layer constant thermal properti assum year ago drew attent method determin transient temperatur two-layer slab triangular heat-input puls point method applic case extern face sinusoid temperatur variat time method base analog on-dimension heat flow flow electr current simpl transmiss seri resist parallel capacit 