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Linear Graphs
Published in Clarence W. de Silva, Modeling of Dynamic Systems with Engineering Applications, 2023
Analogous to electrical amplifiers, a mechanical amplifier can be designed to provide force amplification (a T-type amplifier) or a fluid amplifier can be designed to provide pressure amplification (an A-type amplifier). In these situations, typically, the device is active and an external power source is needed to operate the amplifier (to drive a combination of motor and a mechanical load, for example).
Linear Graphs
Published in Clarence W. de Silva, Modeling of Dynamic Systems with Engineering Applications, 2017
Analogous to electrical amplifiers, a mechanical amplifier can be designed to provide force amplification (a T-type amplifier) or a fluid amplifier can be designed to provide pressure amplification (an A-type amplifier). In these situations, typically, the device is active, and an external power source is needed to operate the amplifier (e.g., to drive a combination of motor and a mechanical load).
Influence of frequency change during sandstone erosion by pulsed waterjet
Published in Materials and Manufacturing Processes, 2020
Rupam Tripathi, Sergej Hloch, Somnath Chattopadhyaya, Dagmar Klichová, Jiří Klich
The PWJ in this study uses ultrasonic generators for the generation of pulses. The pressure fluctuations are originated by an acoustic actuator which is attached to the acoustic chamber filled with fluid under pressure. The acoustic actuator works as a transformer which transforms the electric signals into mechanical signals and intensifies in the mechanical amplifier. The pressurized liquid is amplified by the mechanical amplifier which is transferred by liquid waveguide to the nozzle. The tunning of liquid compressibility and acoustic system is utilized for the transfer of energy from the generator to the nozzle system. The acoustic chamber consists of a resonant chamber for regulating the natural frequency to the pressure fluctuation frequency.[8,9]
Airborne power ultrasound for paper drying: an experimental study
Published in Drying Technology, 2023
Zahra Noori O’Connor, Jamal S. Yagoobi
A unique experimental setup was designed and assembled as shown in Figure 1. The main components include the transducer part, electric power generator or EPG (power amplifier and dynamic resonance controller) and sample holder. The sample holder is a stainless steel mesh with 5 mm size circular holes to allow for the moisture mist to escape from the underneath of sample as well. The sound level around the transducer in free field is about 160 dB. For safety purposes, composite double layers soundproofing foams (quiet barrier specialty composite, Soundproofing Cow company, Pennsylvania, USA) were used to reduce the sound level around the transducer to less than 80 dB. It should be noted that this is an open system, and the door of the setup was kept open during the experiments. This airborne transducer and EPG was purchased from Pusonics S.L. (Madrid, Spain). According to the manufacturer,[19] the transducer is composed of a piezoelectric Langevin-type sandwich, a mechanical amplifier or horn, and an extensive radiator, that provides the required impedance to match with the media. The transducer plate is made from titanium and its dimensions are 43.323.43.14 cm. In this study, the ultrasound power is 225 W (the maximum power recommended by the manufacturer) and working frequency is 21 kHz. The weight of the samples was measured intermittently at 2 min intervals using a microbalance (Sartorius BCE6200, Gottingen, Germany, with 0.001 g accuracy). The samples’ thickness was gauged using a digital thickness gauge with 0.002 mm accuracy.
Airborne power ultrasound for drying process intensification at low temperatures: Use of a stepped-grooved plate transducer
Published in Drying Technology, 2021
R. R. Andrés, E. Riera, J. A. Gallego-Juárez, A. Mulet, J. V. García-Pérez, J. A. Cárcel
The APU transducer, developed by CSIC and Pusonics, consists of a Langevin transducer, a mechanical amplifier and a stepped circular plate radiator (SCPR) to ensure a coherent ultrasonic radiation. The ultrasonic system operates at working mode with an extensional vibration for the Langevin sandwich and the horn, and a flexural vibration with seven nodal circles (7NC) for the circular radiator at a frequency around 26 kHz. The APU transducer is described in detail by Andrés et al.[58,59] The operational mode of the transducer, determined numerically by FEM, with a flexural mode with 7NC, is shown in Figure 3. The transducer needs an electric supply and guidelines to vibrate at the required frequency with the desired amplitude. The generation system is placed outside the cabinet and is composed of a dynamic resonance frequency control unit (ultrasonic controller), which provides adjustable continuous power output at the resonance frequency of the transducer by keeping the voltage (V) and current (I) signals in phase, and tracking the resonance when the frequency shifts during operation.[60,61] The controller operates as a finely tuned electronic signal generator which sends the excitation signal to the transducer through an embedded impedance matching unit. This allows maximum energy transfer between the electronics and the transducer, by adapting the output impedance to the impedance of the transducer (about 500 ohm under resonance). To keep the system in resonance, samples of the voltage and current signals are taken at the output of the ultrasonic controller to measure the electrical response of the transducer.