nocturnal emission reflex emission of semen during sleep. thermionic emission the application of heat, such as to a filament, resulting in the emission of electrons and ions. thermionic emission
Which means if the equipment if design to has a high factor of safety, the cost to fabricate the equipment will increase and same to the weight too. But if the equipment is design with low cost and low weight, the factor of safety will be low too.
Safety factor. 1  the inherent variability of the load (eg. in practice the mass of a ten tonne truck will depend on the load it's carrying), 2  static indeterminacy (when components share the load in proportion to their elastic responses - more of this anon),