The paper raises and proves an essential condition of volumetric property of nonnegative secondary estimation of deviation and variance in linear model.
文中给出并证明了在椭球约束条件下线性模型中，误差方差的非负二次估计的可容许性问题的一个必要条件。
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Detecting rate of the secondary gauge along with the variance of water quantity is analyzed, therefore, leakage can be identified. This method can reduce water consumption.