1. Department of Agricultural Machinery, Agrarian and Industrial Faculty, University of Ruse “Angel Kanchev”, 7017 Ruse, Bulgaria
2. Department of Automation and Electronics, Faculty of Electrical Engineering, Electronics, and Automation, University of Ruse “Angel Kanchev”, 7017 Ruse, Bulgaria
3. Department of Mechanics and Elements of Machines, Technical University of Varna, 9010 Varna, Bulgaria