Trình bày 1 bản báo cáo kinh tế kỹ thuật đầu tư dư án lắp đặt trạm biến áp

Coiled springs ought to be very strong and stiff. si3n4 is a strong, stiff material. would you select this material for a spring? explain.

Starting wih an energy balance on a rectangular volume element, derive the one- dimensional transient heat conduction equation for a plane wall with constant thermal conductivity and no heat generation.

Plot schematically the tensile stress versus strain curves for a typical thermoplastic material at a temperature below its glass transition temperature (tg and at a temperature above its tg, respectively. do the same for a typical thermosetting material. list in a table any differences or similarities between the two materials at t> tg and t < tg, respectively, and relate them to the structures of the two types of polymers