List of Articles Efficiency Open Access Article Abstract Page Full-Text 1 - Method of Evaluation of Efficiency Improvement Potential for District Heating Systems with Focus on Variable Speed Centrifugal Pumps Egils Dzelzitis Deniss Pilscikovs Open Access Article Abstract Page Full-Text 2 - Exergy Analysis of Evaporative Cooling for Optimum Energy Consumption in Diverse Climate Conditions معین فرهانی هادی پاسدار شهری Open Access Article Abstract Page Full-Text 3 - Hydrodynamic Design of Contra-Rotating Propeller for the Ships حسن قاسمی رویا شادمانی Open Access Article Abstract Page Full-Text 4 - Evaluation of the magnetic field effect on stepped solar still efficiency hamidreza goshayeshi kimya samadi vahid nejati Reza Saleh Isaa Chaer