Where, V is the comprehensive evaluation value of quality characteristics, Vi is the metric value of corresponding quality characteristic, Vsij is the metric value
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of corresponding sub-characteristic, vijk is the metric value of corresponding metric item, Nq is the count of characteristics, Nsi is the count of corresponding sub- characteristic, Nmij is the count of corresponding metric item, i is the weight coefficient of corresponding characteristic, sij is the weight coefficient of corresponding sub- characteristic, mijk is the weight coefficient of corresponding metric item.