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. The variability of the strength of glass due to limitations of the manufacturing process means a suitable safety factor must be used when calculating glass thickness. The factor commonly used is 3.8. While not a perfect guarantee, it will remove all risk bar that of damaged or very poor quality glass.