four-dimensional spacetime

GIS application to construction and production in mines is analyzed . Data storage structure of GIS is emphatically studied . Four-dimensional spacetime data structure is integrated with mine production .

分析了GIS在矿山建设和生产管理中的综合应用，着重研究了GIS中的数据存贮结构，将四维时空数据结构与矿井生产相联系，并探讨了矿山GIS所包含的内容。

We find that the probability for the Yang-Mills baby universe to undergo a spontaneous compactification down to a four-dimensional spacetime is greater than that to remain in the original homogeneous multidimensional state .

我们发现仅对于Yang-Millsbaby宇宙，流形紧致到四维时空的几率才可能最大。

Secondly , we investigate the energy density produced by a state vector which is the superposition of three single electron states in the Dirac field in the four-dimensional Minkowski spacetime .

然后，研究了在四维平直时空下三个单粒子态构成的量子态的负能密度。