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Found 5152 publications

Object-oriented database schema analysis and inheritance processing: A graph-theoretic approach

Michele Missikoff Anna Formica H. Dietmar Groger

Publication Name: Data and Knowledge Engineering

Publication Date: 1997-01-01

Volume: 24

Issue: 2

Page Range: 157-181

Description:

In this paper we address the inheritance process in the context of strongly typed Object-oriented database (OODB) systems, allowing multiple inheritance and overriding. For such powerful systems, it is important to analyse the inheritance hierarchy to identify a number of significant properties. The first, schema consistency, is connected to the inheritance conflicts. In the presence of an unsolvable inheritance conflict there is a contradiction in the schema. The second property is related to the termination of the inheritance process. We expect that all the subtypes in the schema, if consistent, can be rewritten in expanded form, after inheritance, in a finite time. Schemas that guarantee these two formal properties will be referred to as correct schemas. In the paper a graph-theoretic method is provided, aimed at supporting the designer in checking the correctness and deriving the expanded form of a schema. Furthermore, from the analysis of the complexity of the inheritance process, a third formal property has been defined, concerning the degree of compactness achievable in a schema, by using inheritance hierarchies. In particular, a class of schemas has been defined, referred to as logarithmic schemas, whose expanded forms, after inheritance, become exponential in the size of the original schemas.

Open Access: Yes

DOI: 10.1016/S0169-023X(97)00018-9

Comprehensive method for the test calculation of complex digital circuits

J. Sziray

Publication Name: Periodica Polytechnica Electrical Engineering

Publication Date: 1997-01-01

Volume: 41

Issue: 4

Page Range: 251-257

Description:

The paper presents a general test calculation principle which serves for producing tests for a wide range of possible faults: stuck-at-constant logic level (single, multiple), bridging (single), as well as behavioral (functional, single) faults. The proposed method handles multi-valued logic, where the number of logic values is unlimited. The level of circuit modeling is also allowed to vary in a wide range: switch level, gate level, functional level, etc. are equally allowed. Both combinational and sequential circuits are considered. The principle is comparatively simple, and it yields an opportunity to be realized by an efficient computer program.

Open Access: Yes

DOI: DOI not available

Analysis of railway vehicles' bogies with different wheel forces

Laszlo Bozoky Vince Nagy

Publication Name: Proceedings of the Mini Conference on Vehicle System Dynamics Identification and Anomalies

Publication Date: 1996-12-01

Volume: Unknown

Issue: Unknown

Page Range: 203-213

Description:

For the past ten years, geometry and loaded tests on railway bogies are in progress at the Department for Automotive and Railway Engineering of Szechenyi Istvan College. Following analysis of running and driven bogies and laboratory measurements, operating test of running vehicles has also been conducted. Initial results made it possible to perform different theoretical and computer analysis.

Open Access: Yes

DOI: DOI not available

Residual elimination algorithm for solving linear equations and application for sparse systems

B. Török G. Molnárka

Publication Name: ZAMM Zeitschrift Fur Angewandte Mathematik Und Mechanik

Publication Date: 1996-12-01

Volume: 76

Issue: SUPPL. 1

Page Range: 485-486

Description:

A new direct algorithm for solving linear system of equations will be presented. Short theoretical background and analysis of the proposed method will be given. We formulate an optimized version of the proposed algorithm, which also works for sparse matrices. The complexity of the suggested algorithm for full matrix systems is n3/3 H- O(n2) where n is the dimension of the problem. The numerical experiments show that some versions of the residual elimination algorithm can be competitive with the Gaussian elimination both in complexity and precision. Moreover the sparse linear solver based on this algorithm has some advantages in parallel environment.

Open Access: Yes

DOI: DOI not available

Analysis of railway vehicles' bogies with different wheel forces

No authors available

Publication Name: Proceedings of the Mini Conference on Vehicle System Dynamics, Identification and Anomalies

Publication Date: 1996-12-01

Volume:

Issue:

Page Range: 203-213

Description:

For the past ten years, geometry and loaded tests on railway bogies are in progress at the Department for Automotive and Railway Engineering of Szechenyi Istvan College. Following analysis of running and driven bogies and laboratory measurements, operating test of running vehicles has also been conducted. Initial results made it possible to perform different theoretical and computer analysis.

Open Access: No

DOI: DOI not available

Residual elimination algorithm for solving linear equations and application for sparse systems

No authors available

Publication Name: ZAMM Zeitschrift fur Angewandte Mathematik und Mechanik

Publication Date: 1996-12-01

Volume: 76

Issue: SUPPL. 1

Page Range: 485-486

Description:

A new direct algorithm for solving linear system of equations will be presented. Short theoretical background and analysis of the proposed method will be given. We formulate an optimized version of the proposed algorithm, which also works for sparse matrices. The complexity of the suggested algorithm for full matrix systems is n3/3 H- O(n2) where n is the dimension of the problem. The numerical experiments show that some versions of the residual elimination algorithm can be competitive with the Gaussian elimination both in complexity and precision. Moreover the sparse linear solver based on this algorithm has some advantages in parallel environment.

Open Access: No

DOI: DOI not available

Environmental management model: an analysis on the relations of the components of environmental management

No authors available

Publication Name: Proceedings of the 1st International Conference on Environmental Engineering Education and Training, EEET'96

Publication Date: 1996-01-01

Volume:

Issue:

Page Range: 151-159

Description:

The theme of the essay: The presentation of an environmental analysis model Aim and utility: environmental condition varieties as well as effects on people; economic and social activities behind the effects and their influence on changing environmental policy regulations; establish a conceptual organization which can support the analysis of interactions.

Open Access: No

DOI: DOI not available

Experimental determination of plastic zones

E. Czoboly I. Havas B. Csizmazia

Publication Name: Materials Science

Publication Date: 1996-01-01

Volume: 32

Issue: 1

Page Range: 87-98

Description:

We present four experimental series for the determination of the size and shape of plastic zones due to monotonic and cyclic loadings. Specimens contain notches of various geometries but not cracks. This provides the possibility to study the effect of notch radius and the repetitions of loading without the disturbing influence of crack closure and the previous loading history. Different steels and aluminum alloys are involved. It is shown that the size of the zone increases significantly as a function of load cycles. © 1997 Plenum Publishing Corporation.

Open Access: Yes

DOI: 10.1007/BF02538929

Environmental management model: an analysis on the relations of the components of environmental management

M. Bulla

Publication Name: Proceedings of the 1st International Conference on Environmental Engineering Education and Training Eeet 96

Publication Date: 1996-01-01

Volume: Unknown

Issue: Unknown

Page Range: 151-159

Description:

The theme of the essay: The presentation of an environmental analysis model Aim and utility: environmental condition varieties as well as effects on people; economic and social activities behind the effects and their influence on changing environmental policy regulations; establish a conceptual organization which can support the analysis of interactions.

Open Access: Yes

DOI: DOI not available