What is one of the biggest challenges to get computers to identify objects?

Thermal stresses are developed in a metal when its a) initial temperature is changed b) final temperature is changed c) density is changed d) thermal deformation is prevented e) expansion is prevented f) contraction is prevented

Burgers vector is generally parallel to the dislocation line. a)-true b)-false

Draw the engineering stress-strain curve for (a) bcc; (b) fcc metals and mark important points.