In English. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.



Volume 49 No. 4 December 2000


Piano hammer testing device; 259–267

Anatoli STULOV and Avo MÄGI

Abstract. The piano hammer testing device described here makes it possible to investigate the dynamic force–compression characteristics of the piano hammer and, using the hereditary (hysteretic) hammer model, to find the hammer parameters by numerical simulation of the dynamic experiments.

Key words: grand piano, piano hammer, hammer model, hammer–string interaction.



Performance of dissipated wind turbines; 268–277

Teolan TOMSON and Maire HANSEN

Abstract. Strong dependence of the generated wind power on the wind speed makes the incorporation of large scale wind energy into Estonian power supply system difficult. In the paper it is shown that distribution of the wind turbines over a wider geographic area may solve this problem.

Key words: wind dynamics, wind energy, dissipation of wind turbines


Calculation of load of the domestic hot water heat exchanger in residential buildings; 278–283

Teet-Andrus KÕIV and Alvar TOODE

Abstract. Different methods of load calculation of domestic hot water instantaneous heaters in residential buildings are described. Results of the calculation of the heat load for various numbers of apartments in a building are presented. A load calculation formula of domestic hot water heat exchangers for residential buildings in Estonia is recommended. Heat load calculation results by the recommended and the Swedish District Heating Association method are compared. Actual average loads of heat exchangers in renovated heat substations are compared with the calculated ones.

Key words: domestic hot water heat exchanger load, calculation methods.


Comparative calculation of flows in the straits of the Gulf of Riga and the Väinameri; 284–294


Abstract. Two hydrodynamic models are applied for flow calculations in the Gulf of Riga and the Väinameri subbasins. The correlation between the measured and modelled time series and between the time series obtained with both models is high. The analysis of the modelled flows within the regions of the straits proved that in the straits of the Väinameri the flows are spatially unidirectional. In the wider Irbe Strait the velocity vectors in the strait are not so uniformly directed. However, a horizontal two-directional flow regime is quite rare and probably it is possible to get representative water exchange estimates at one point even in that strait.

Key words: currents, channels, hydrodynamic modelling, 2D models, measurements, Baltic Sea.



Ingredient mass measurement and uncertainty; 295–309


Abstract. To compose a material or a solution in required quantities, it is necessary to measure ingredient mass or volume. The paper analyses the weighing procedures taking into account specific conditions in Estonia. An analysis of the assurance of the traceability of the mass measurement unit in Estonian calibration and testing laboratories is presented. Calculation of the uncertainties by weighing is considered. An overview of the results of the first proficiency testing of Estonian mass calibration laboratories is given.

Key words: reference material, ingredient mass, weighing, uncertainty, quality assurance.





Rein Küttner 60; 310