— The design of a data base schema can be organized through a set of refînement steps, that gradually introducé progressive details in the description of reality. In this approach, suitable restrictions to refînement rules allow to guarantee both conceptual and logical properties. Following this approach the formalism of hypergraphs and hypergraph grammars can be applied to investigate various ...

In this paper we briefly present the design of a distributed relational data base system. Then, we discuss experimental observations of the performance of that system executing both short and long commands. Conclusions are also drawn concerning metrics that distributed query processing heuristics should attempt to minimize. Lastly, we comment on architectures which appear viable for distributed...

In this paper it is attempted to predict the off-design performance of a jet engine. After a review of the governing equations, the off-design performance is investigated by two methods. In the first method, the component characteristic curves of the Gas Turbines are used. In the second method some design point parameters and the reference state conditions are employed. The results obtained by ...

  Ceramic materials due to their high compressive strength and hardness have been one of prime candidates in armor design in particular when high level threads (impact velocity above 600m/s) are involved. The aim of this work is to investigate ballistic impact resistance potential for a target plate with novel ceramic inserts as against ceramic tiles. Two size 98% alumina (AL2O3) base ceramic i...