根据湍流的动能和动能耗散率输运方程，建立了折射率起伏方差的计算模型。

Based on turbulent kinetic energy and the rate of turbulent dissipation transport equations, the equation to calculate variance of the refractivity fluctuation is modeled.

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根据接触悬挂系统中的接触线振动方程，推导了接触线应力的均值和方差的计算公式。

Vibration equations of contact wires were used to derive the formulae for calculation of mean and standard deviations of stresses.

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协变和逆变的区别对于张量的计算尤为重要，这往往会出现混合方差。

The distinction between covariance and contravariance is important for computations with tensors, which often have mixed variance.

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In fact, I have it--suppose we have three assets and we want to compute the efficient portfolio frontier, the mean and variance of the portfolio.

事实上，假如我们拥有三种资产,我们想计算有效边界，及投资组合的均值和方差。

耶鲁公开课 - 金融市场课程节选

They might say my sample period was off, ... but that's what the theory-- ... using my data for the sample period that I computed-- the expected returns and co-variances says one should do.

他们可能说我的采样周期是有问题的，不过我的结果都是靠理论-,我采用自己收集的数据计算出-,预期收益和协方差可以用来指导我们的投资行为。

耶鲁公开课 - 金融市场课程节选

What we want to do now is compute the mean and variance of the portfolio-- or the mean and standard deviation, since standard deviation is the square root of the variance-- for different combinations of the portfolios.

我们现在要做的是,计算这个投资组合的均值和方差-,或者均值和标准差，因为标准差的平方就等于方差-,这对任何投资组合都是一样的。

耶鲁公开课 - 金融市场课程节选