Institute of Environment and Energy Systems, Faculty of Energy and Electrical Engineering, Riga Technical University, Kronvalda blvd. 1, Riga, LV 1010, Latvia
D. Zahare
Institute of Environment and Energy Systems, Faculty of Energy and Electrical Engineering, Riga Technical University, Kronvalda blvd. 1, Riga, LV 1010, Latvia
A. Blumberga
Institute of Environment and Energy Systems, Faculty of Energy and Electrical Engineering, Riga Technical University, Kronvalda blvd. 1, Riga, LV 1010, Latvia
A. Kamenders
Institute of Environment and Energy Systems, Faculty of Energy and Electrical Engineering, Riga Technical University, Kronvalda blvd. 1, Riga, LV 1010, Latvia