Design of new ultrasonic transducer with two elements for flow rate measurement using ultrasonic Doppler methodJevin Tanius Owen, Ari Hamdani, Tomonori Ihara, Hideharu Takahashi and Hiroshige KikuraE3S Web Conf., 43 (2018) 01011DOI: https://doi.org/10.1051/e3sconf/20184301011