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t=O T1 T2 NowA spatio-temporal data structure, called the PMD-tree (Persistent Multi-Dimensional tree), has been proposed for managing the live intervals and locations of spatial objects. In the paper, novel concepts of time space bounding box (TSBB) and motion Iist are introduced to the PMD-tree to manage moving spatial objects efficiently. TSBB is an extended bounding box for a moving object that covers the trajectory ofthe object. As an object moves, a E B B corresponding to the object is enlarged to enclose the trajectory of the object. A TSBB is divided, when it becomes greater than a limit. An object and corresponding EBBS are managed by a doubly connected linked list, called motion list. TSBBs are also managed by the PMD-tree. Introducing the concept of TSBB and motion list to the PMD-tree, moving objects can be efficiently managed and be quickly found for spatiotemporal queries. By the series of simulation tests, the storage requirements and search performances are evaluated for several types of moving objects.

In the engineering database system, multiple versions of a design including engineering drawings should be managed efficiently. Spatial data structures can manage spatial objects in a drawing efficiently. The paper proposes extended spatial data structures for efficient management of multiversion engineering drawings. The Rtree is adapted as a basic data structure. The efficient mechanism to manage the difference between drawings is introduced to the R-tree to eliminate redundant duplications and to reduce the amount of storage required for the data structure. The extended data structures of the R-tree, MVR and MVR* trees, are developed and the performances of these trees are evaluated. A series of simulation tests shows that, compared with the basic R-tree, the amounts of storage required for the MVR and MVR* trees are reduced to 50% and 30%, respectively. The search efficiencies of the R, MVR, and MVR* trees are almost the same.

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