The problem of structure optimization in supply is essentially how to determine the supplier number. The number of suppliers is related to the supply risk and total purchase cost.

在定量分析供应商数量与供应风险及采购总成本关系的基础上，建立了多目标优化模型。

youdao

Your cost of doing this analysis is limited to gathering information in a detailed request for purchase (RFP) and evaluating the total costs in the responses.

进行这种分析的成本仅限于将信息搜集到详细的采购申请书(RFP)中和计算回响应中的总成本。

youdao

Even though you save on kerosene, it takes more than three years after purchase for the total cost of running a compact fluorescent lamp to drop below that of a kerosene lamp and fuel.

如果不用煤油灯，节省下来的灯油钱，要三年才抵得上购买一个紧凑型灯的花费。

youdao

If you spread the purchase and sale costs over a longer period, your total annual cost will be lower.

WSJ: Calculating the Costs of Investing in ETFs