In English. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.



Volume 8 No. 1 March 2002


Techniques of combination of metamodel extensions; 3–17

Alar Raabe

Abstract. Extensions to the generic analysis and design metamodels (for example, UML meta-models) are needed to support an effective analysis and design process. Extended analysis meta-models that embody domain knowledge, and extended design metamodels which embody architecture-specific knowledge, can be used in software engineering as a guiding framework. Therefore it is necessary to combine several metamodel extensions. In the article solutions for combining several metamodel extensions and for the interoperability of metamodel extensions are presented. We also discuss how model transformations can use metamodel extensions.

Key words: metamodelling, metamodels, metamodel extensions, UML.

On technical management of large power transmission networks; 18–37

Taivo Kangilaski

Abstract. This article considers problems which arise by technical management of large transmission networks and describes a technical software-related management system “Event Navigator”, developed at Eesti Energia AS.

Key words: transmission network, technical management, software.

Formation of microstructure of spray-fused powder coatings; 38–51

Priit Kulu, Toomas Pihl, Kristi Tammjärv, and Petri Vuoristo

Abstract. The paper describes a NiCrSiB self-fluxing alloys based system, containing particles of tungsten carbide or those of WC-Co hardmetal from the used hardmetal as hard phase, deposited by the spray and fusion processes. Flame and laser spray fusions were used as coating technologies. The study focuses on powder composition, hard phase grain size, processes of deposition, the effect of the composition and process on the formation of the coating structure, and on the evaluation of wear resistance of coatings. We discuss the dependence of the wear resistance of spray-fused coatings on their structure and propose structure criteria for coating selection. The “double cemented” matrix structure of self-fluxing NiCrSiB based coatings, which contain WC-Co particles, was found optimal in impact erosion wear conditions. The paper also discusses the cost-effectiveness of coatings in application areas that are sensitive to the cost and which prefer composite coatings based on low cost recycled materials.

Key words: thermal spray, flame spray and fusion, laser spray and fusion, composite coatings, impact erosion, wear.

Identification of the wheelbase of road vehicles from wheel speed signals; 52–57

Péter Frank and Ansgar Fries

Abstract. Electronically controlled brake systems are nowadays widely used in road vehicles. The control systems consist of sensors, actuators, and of the electronic control unit. To reduce the number of system components is a permanent market need. Therefore the intelligence of the control software should be improved. One direction of improvement is the implementation of adaptive algorithms. The latter allow to renounce some pre-programmed parameters. The paper presents a simple method for the identification of the wheelbase of road vehicles by evaluating the wheel speed signals only. The method uses the correlation between noisy speed signals of wheels running on the same road track one after another over a bump. Measurements carried out on heavy trucks show the practical value of the method.

Key words: electronically controlled brake system, road excitation, parameter identification, correlation.



Boris Tamm; 58–59


Instructions to authors; 60–62

Copyright Transfer Agreement; 63