The spatiotemporal index for the constraint network is one of the key issues in this field.

受限网络中的时空索引是解决此类时空数据管理问题的关键所在。

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On the basis of this model , the author put forward a R-tree based Composite Spatiotemporal Index (CST-TREE) and described its structure and mechanism.

并在此模型上提出了一个基于R树的复合时空索引（CST-TREE）机制，定义了节点结构，并分析、描述了此索引的结构及原理。

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Urban air quality level is token by air quality index (API), whose spatiotemporal change can reflect the change of urban air quality.

城市空气质量水平是以空气质量指数(API)来表征的，API的时空变化可以反映城市空气质量的变化过程。

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