Deductive databases result from the integration of relational database and logic programming techniques. However, significant problems remain inherent in this simple synthesis from the language point of view. In this ...
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Deductive databases result from the integration of relational database and logic programming techniques. However, significant problems remain inherent in this simple synthesis from the language point of view. In this paper, we discuss these problems from four different aspects: complex values, object orientation, higher-orderness, and updates. In each case, we examine four typical languages that address the corresponding issues.
Paredaens and Van Gucht proved that the flat relational algebra has the same expressive power as the nestedrelational algebra, as far as queries over flat relations and with flat results are concerned. We provide a n...
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Paredaens and Van Gucht proved that the flat relational algebra has the same expressive power as the nestedrelational algebra, as far as queries over flat relations and with flat results are concerned. We provide a new, very direct proof of this fact using a simulation technique. Our technique is also applied to partially answer a question posed by Suciu and Paredaens regarding the complexity of evaluating powerset algebra expressions. Specifically, we show that when only unary fiat relations are into play, any powerset algebra expression is either equivalent to a nested algebra expression, or its evaluation will produce intermediate results of exponential size. (C) 2001 Elsevier Science B.V. All rights reserved.
The main task of an information system is the representation and management of large amounts of indicative information from multiple sources describing the state of some enterprise. Most conceptual and database models...
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Lifecycle structural health monitoring (SHM) systems provide an abundance of information that is greatly beneficial for securing structural safety over the whole service life. In application to large-scale structures,...
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Lifecycle structural health monitoring (SHM) systems provide an abundance of information that is greatly beneficial for securing structural safety over the whole service life. In application to large-scale structures, the management of accumulated massive data from a sophisticated long-term SHM system poses a challenge. A robust data management system (DMS), which not only facilitates spatiotemporal data management but also enables display in an attractive way, is highly desirable. This article presents the development of an effective visualized DMS specific for managing immense and heterogeneous SHM data by integrating nestedrelational database, three-dimensional (3D) model, and virtual reality (VR) technology and demonstrates its application to an instrumented supertall structure. A custom nested data model is designed to store redundant inherent temporal data and hierarchical inherent spatial data. Strategies for speeding up querying massive data are set up in the database. Making use of OpenSceneGraph (OSG) 3D engine, a 3D model is reconstructed from the 3D spatial data, which serves as a platform for data visualization. A four-dimensional (4D) animation protocol is presented by tying temporal data and construction schedule to the 3D model. The efficiency of the proposed DMS is exemplified through its application to a supertall structure instrumented with a sophisticated long-term SHM system. (C) 2016 American Society of Civil Engineers.
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