Proceedings of the Estonian Academy of Sciences

CONTENTS & ABSTRACTS

In English. Summaries in Estonian

Proceedings of the Estonian Academy of Sciences.

Engineering

Volume 11 No. 3 September 2005

Microstructural evolution and mechanical properties of nanostructured copper; 187–197

Lembit Kommel, Irina Hussainova, Olga Volobueva and Rünno Lõhmus

Abstract. Nanostructured metallic materials exhibit outstanding mechanical properties. Pure copper was chosen as a test material and was subjected to an equal channel angular pressing to produce a nanostructure. The paper analyses development of the microstructure during severe plastic deformation of copper and mechanical properties of the metal. Tests show that the nanocristalline copper possesses high tensile strength and microhardness as well as high plasticity after hard cyclic viscoplastic deformation. However, heat treatment and method of deformation influence the properties to a large extent. Dependence of the changes in structural parameters and properties on the deformation process and heat treatment are studied.

Key words: nanocrystalline copper, nanostructure, mechanical properties, severe plastic deformation.

Simulation and analysis of thermal performance of an apartment building; 198–206

Kadi Kusnetsov and Teet-Andrus Kõiv

Abstract. The paper describes results of the computer simulation of the thermal performance of an apartment building. Results concerning heat requirements, heating load and indoor climate simulation are given. Applying heating load analysis in apartment buildings without individual temperature control, it is possible to reduce heat consumption for heating.

Key words: apartment building, thermal performance, simulation, TRY.

Investigation of the domestic hot water consumption in apartment buildings; 207–214

Alvar Toode and Teet-Andrus Kõiv

Abstract. Domestic hot water consumption profile in five apartment buildings is investigated. Consumption profiles in 1973 and 2003 are compared. Domestic hot and total water consumption data within the last five years are presented. Decrease in domestic hot water consumption is one of the main reasons for decrease in the heat requirements in typical apartment buildings.

Key words: domestic hot water, consumption profile.

Behaviour of wind speed fronts; 215–225

Teolan Tomson and Maire Hansen

Abstract. This article describes methods for determining wind speed increments in relation to wind fronts and their dependence on the height of measurement, average wind speed and wind direction. Wind directions and speeds, which can produce the most powerful wind fronts, significant for the performance of the Estonian power system, are analysed. The impact of wind speed fronts to the behaviour of a grid of wind turbine generators is assessed.

Key words: wind speed front, frequency distribution function, power system.

Group-mode performance of wind turbine generators; 226–233

Teolan Tomson

Abstract. in the paper the influence of the wind power increments on the group-mode performance of wind turbine generators (WTG) has been studied. It is proved that with increasing distance between WTGs, the suppression of global wind power increments in the group will increase. Wind power increments in the sheltered landscape (inland) are lower than in the coastal zone and the positive effect of group-mode performance is reduced.

Key words: wind power, wind turbine generator, group-mode performance.

An algorithm of the formation of waste load in industrial effluents; 234–244

Jüri Säärekõnno

Abstract. Nowadays industry is facing significant new challenges as the production processes must become more sustainable. Therefore the environmental impact assessment is necessary for any company. In this study an algorithm, describing the formation of the load of residue substances in industrial effluents, is presented. The algorithm, expressed in the form of a limiting state equation, enables assessment of the environmental impact either of the total effluent of the company (integral level of analysis) or of one effluent from each water use unit (differential level). This analysis represents a part of the wider (total) environmental impact assessment of the company that may be carried out together with the product life cycle assessment.

Key words: industrial effluents, pollutant substances, waste load, modelling, limiting state equation, environmental impact assessment.

Profiles of waves from high-speed ferries in the coastal area of Tallinn Bay; 245–260

Tarmo Soomere, Reio Põder, Kalev Rannat and Andres Kask

Abstract. The shape and properties of long ship-generated waves approaching shallow coastal areas of Tallinn Bay are studied based on recordings of water surface time series. For typical leading wake waves non-linear effects become significant at depths of 10–15 m. A large part of waves (with the height over 0.4 m) have the shape of cnoidal waves in shallow areas with depths of 4–5 m. The shapes of the largest wake waves are close to the solitary wave solutions of the Korteweg–de Vries equation. Such waves excite considerably larger velocities of water particles than sinusoidal waves of equal height and length.

Key words: fast ferries, ship wash, cnoidal waves, wave measurements.

Instructions to authors; 261–263