在轻和黑之间的变化的水准在一幅图像或者在他们最大之间的比率内估价领域以及最小价值。

The level of variation between light and dark values areas in an image, or the ratio between their maximum and minimum values.

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叶面积比率的生物学特征最为明显，冬小麦返青到拔节期间的叶面积比率最大，拔节之后，叶面积比率逐渐下降，在冬小麦乳熟期前后达到最小。

The most distinctive biological feature is the Leaf Area Ratio(LAR), it is higher in former phase and lower in later, and decline to its smallest around the period of Milky Ripeness.

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假定投资者是绝对的风险厌恶者，其保值的目的是将风险最小化，由此得到最小方差下的套期保值比率。

Assume investors are absolute risk averter, and it is their aim to minimize its risk, and get hedge ratio under it.

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