One theory is that they are youngsters, giving off heat as they collapse inward due to the pull of their own gravity, but nobody knows for sure.
有一个说法是，它们还处于幼年，由于自己的重力所拉，在衰竭的同时发出热量，但没有人能肯定这种说法。
2
To study heat input of metal parts in deposition forming is favorable for forecasting and avoiding flow and collapse in deposition layers.
研究金属零件熔积成形中的热输入有利于预测和避免熔积层中出现流淌和坍塌现象。
3
They should also meet the requirements in preventing and avoiding disasters caused by mountainside landslide rock collapse mud-rock flow tropical heat wave fire etc.