In this paper, we introduce a composable and extensible drone with tilting rotors (CEDTR). We aimed for a function that could optimally match the load capacity, degree of freedom (DOF), speed and endurance with diverse mission requirements by changing the quantity and form of combinations. First, we propose a decentralized modular controller to allow a team of physically connected modules to fly cooperatively. Second, we divide all the combinations into three categories according to the different control methods. Three generalized control strategies are proposed to control both position and attitude independently by tilting the directions of the propellers. We carried out experiments to demonstrate the feasibility of this mechanical design and control method. The experiment video is available at https://youtu.be/7RvxiV4FPq4.

Pushing down predicates to an external data source is critical to the performance for querying heterogeneous data sources. However, predicate-containing string comparisons cannot be pushed down unchanged if the external data source uses a different collating sequence. We describe a table-driven technique for rewriting such predicates to account for the differences in collation. In addition to precise conversion, we also consider imprecise conversion.