本文采用成本与效益分析的方法，从经济上对矿井合理服务年限的定量问题，作了理论上的探讨。
The optimal service life of a mine is discussed theoretically from economic point of view by analysing the cost and benefit.
结合具体工程项目，重点分析如何依据经济条件，采用偿还年限回收方法对配电电缆截面进行经济性选择，以便选出理想截面。
Distribution power cable section is choosed economically by means of refund fixed number of year reclaim based on concrete project in order to choose perfect cable section.
通过有限生命周期内微型冷库经济性能的分析，推导了微型冷库在使用年限不同时的经济保温层厚度计算公式。
The calculation equation of the economic insulating layer thickness in different service life was (derived) through the life cycle economical analysis of the mini-cold storage.
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