本文以极简单的数学推导，给出了正常重力垂直梯度的实用表达式，并对其精度作出了评价。
By very simple mathematical derivations, the practical expression of (Vzz), the expression of normal vertical gravity gradient, and the comment on the accuracy were given.
提出了一个新的非线性迟滞隔振系统的动力学模型，并导出了系统动力学模型的实用表达式。
A new dynamic model for nonlinear hysteresis vibration isolation system is proposed, and the practical representation of dynamic model of the system is derived.
在执行请求之前，部署实用工具会估算每个表达式，并且会考虑到已部署的请求。
Before a request is executed, the deployment utility tool evaluates each expression, taking into account the already deployed request.
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