The reinsurance is to find optimal contact under the different criterion in the economical theorem.
经济理论上的最优再保险就是在不同的优化准则下，寻找最优再保险合同。
2
For further advance the biological contact oxidation was added and the economical benefits analysis on water saving program was done.
为改善水质，在工程设计中增设了生物接触氧化池；同时对该电厂节水技改项目进行了经济效益分析。
3
Among the four electrical power system mentioned before, the most economical and reasonable one is the overhead contact voltage power supply which is supplied by the overhead contact directly.