26,997 research outputs found
Designing role-based view for object-relational databases
Full text linkIn a federated database system, a view mechanism is crucial since it is used to define exportable subsets of data ; to perform a virtual restructuring d ataset; and to construct the integrated schema. The view service in federated databa se systems must be capable of retaining as much semantic information as possible. The object-oriented ( 0 - 0 ) model was considered the suitable canonical data model since it meets the original criteria for canonical model selection. However, with the emergence of stronger object-relational (0 -R ) model, the re is a clear argument for using an 0 - R canonical model in the federation. Hence, research should now focus on th e development of semantically powerful view mechanism for th e newer model. Meanwhile, the availability of real 0 -R technologies offers researchers the opportunity to develop different forms of view mechanisms.
The concept of roles has been widely studied in 0 - 0 modelling and development. The role model represents some characteristics that the traditional 0-0 model lacked, such as object migration, multiple occurrences and context-dependent access. While many forms of 0-0 views were designed for the 0-0 canonical model, one option was to extend the 0-0 model to incorporate a role model. In a role model, the real entity is modelled in the form of a role rather than an object. An object represents the permanent properties of an entity is a root object; and an object represents the temporary properties of an entity is a role object.
The contribution of this research is to design a view system that employees the concept of roles for the 0 -R canonical model in a federated database system. In this thesis, an examination of the current 0 -R metamodel is provided first in order to provide an environment for recognising the roleview metadata and measuring the view performance; then a Roleview Definition Language (RDL) is introduced, along with the semantics for defining virtual classes and generating virtua l extents; finally, a working prototype is provided to prove th e role-based view system is implementable and the syntax is semantically correct
Rede uitgesproken op 17 september 1956 ter gelegenheid van de erepromotie van Dr. Th. von Karman door de promotor Dr. C.B. Biezeno
No full textRede uitgesproken door prof. C.B. Biezeno ter gelegenheid van de erepromotie aan de TH Delft van dr. Theodore von Karman.Precision and Microsystems EngineeringMechanical, Maritime and Materials Engineerin
A Generalization of the Grunwald-Wang Theorem for Powers
Full text linkLet be a natural number greater than and be the smallest prime
dividing . We show that a finite subset of rationals, of cardinality at
most , contains a power in for almost every prime
if and only if contains a perfect power, barring some
exceptions when is even. This generalizes the Grunwald-Wang theorem for
powers, from one rational number to finite subsets of rational
numbers. We also show that the upper bound in this generalization is
optimal for every
Xizicus (Zangxizicus) Wang, Jing, Liu, Li 2014, subgen. nov.
No full textXizicus (Zangxizicus) Wang, Jing, Liu, Li, subgen. nov. Type species: Xizicus (Zangxizicus) quadrifascipes Wang, Jing, Liu, Li, sp. nov., here designated. Body dark brown with blackish stripe, disc of vertex with 4 dark longitudinal bands, tegmina variegated conspicuous dark spots, hind femora with four dark latitudinal bands. Male metazona longer than prozona, no process at hind margin of 10 th abdominal tergite, styli degenerated to small tubercles or disappeared. Etymology. The subgeneric name is derived from the district name of distribution ‘Xizang’ and generic name ‘Xizicus’. Diagnosis. Unlike nominate subgenus, species of this new subgenus without process at hind margin of male 10 th abdominal tergite.Published as part of Wang, Hanqiang, Jing, Jun, Liu, Xianwei & Li, Kai, 2014, Revision on genus Xizicus Gorochov (Orthoptera, Tettigoniidae, Meconematinae, Meconematini) with description of three new species form China, pp. 301-316 in Zootaxa 3861 (4) on page 309, DOI: 10.11646/zootaxa.3861.4.1, http://zenodo.org/record/493037
Prof. Th. W. Adorno and the author Hans Erich Nossack.
No full textProf. Th. W. Adorno and the author Hans Erich Nossack at a reception of Insel Verlag, Buchmesse Frankfurt 1966LB
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
Full text linkThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
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