Spatial data is the main part of the GIS data system, constructing reasonable and efficient spatial indexing has an significant effect on the GIS system performance.

空间数据是GIS系统的主要数据组成部分，建立合理高效的空间数据索引对于GIS系统的性能有着极其显著的影响。

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Curved box girder bridge is a complicated spatial structural system. The effect of prestressing may improve the bearing capacity of the members, but may also adversely affect the structure.

曲线箱形梁桥是空间复杂受力的结构体系，预应力效应一方面能提高构件的承载能力，另一方面也可能对结构带来一些不利的影响。

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