Modeling And Theoretical Characterization Of Circular pMUT For Immersion Applications.

This paper reported modeling and theoretical characterization of circular piezoelectric micromachined ultrasonic transducer (pMUT) for immersion applications

Theoretical Characterization Of Square Piezoelectric Micro Ultrasonic Transducer For Underwater Applications.

There are numerous advantages of employing MEMS based transducer within underwater applications. This work utilized MEMS based acoustic transducer for underwater applications

RETOOLING SCIENCE TEACHING ON STABILITY TOPIC FOR STEM EDUCATION: MALAYSIAN CASE STUDY

By 2020, Malaysia needs to develop its workforce capacity in order to obtain the 500,000 STEM human capital requirement for the New Key Economic Areas (NKEAs). Therefore, an effort of retooling teaching and learning of science teachers is a part of the planning in catalyst STEM human capital. Science teachers require refreshment in teaching and learning approach of pedagogy to enhance the student understanding in the subject matter and stability topic is chose as the initial idea to attract the student interest in STEM activities. This study aims to introduce a teaching aid Arts and Stability Card (A&S Card) to help teachers to diversify the teaching concept of stability science through A&S Card. 300 science teachers across the 10 districts from Perak state, provided their perceptions upon the modules via questionnaire in two parts: a pedagogical approach to teaching and learning, and training suitability. The reliability test of Chronbach’s Alpha to the pedagogical approach to teaching and learning scored 0.868 while training suitability obtained 0.874, which fall under the very good category of reliability results. The mean result score of 4.29 and 4.17 to the pedagogical approach to teaching and learning, and training suitability, where the results indicate A&S Card module and training were successfully conducted. Besides, this module also contains the value of creativity and innovation to build a fun learning in a science subject and the concept can be replicated for other science subject

Development a series ignition circuit for simmer operation of Nd: YAG flashlamp driver

This present paper describes the development of a series ignition circuit for flashlamp driver. A high voltage ignition pulse produced in series with dc simmer power supply. The ignition is based on a single stage of step-up circuit. A small step up transformer was employed together with scr thyristor as a switch to generate high voltage pulse. In this development, ignition circuit was successfully demonstrated the production of giant pulse of 12 kv with duration of less than 1 µs by injecting only 180 v dc. The pulse is enough to ignite and sustains flashlamp in simmer operatio

Characterize the DC power supplies in flashlamp driver

Flashlamp driver comprises one or several charging modules, a discharge and simmer module and a control circuit

Response estimation of micro-acoustic transducer for underwater applications using finite element method

176-180Present study proposed a modeling method to estimate the responses of micro-acoustic transducer and new design of micro acoustic transducer with nickel aluminum bronze encapsulation. Proposed method utilizes finite element analysis by combining the piezoelectric and modal harmonic analyses of micro-structured acoustic transducer. First, novel design of piezoelectric micro-acoustic transducer with nickel aluminum bronze encapsulation was discussed. It was design specifically for sonar applications with resonance frequency at 122 kHz. Next, transmit and receive responses of the transducer was determined using proposed method with reference to underwater acoustic parameter. Finally, the estimation method was validated using existing calibrated transducers by reverse-engineering approach. As the result responses of micro-acoustic transducers were successfully estimated as a function of frequency. New transducer design with nickel aluminum bronze encapsulation has transmit response at 123 dB re 1µPa/V and receive response at -75 dB re 1V/µPa. Validation of the method reveals the average percentage error at 18.97%. Proposed method is useful for micro-acoustic transducer designer to determine responses before entering fabrication process

Transmitting Performance Simulation of Piezoelectric Transducer for Underwater Application

This paper reports transmitting performance simulation of the circular piezoelectric transducer using finite element analysis (FEA) approach. The 3D model of the transducer is designed and simulated using six different piezoelectric materials. FEA simulation and modelling had been carried out using the COMSOL Multiphysics 5.0 software. The thickness and radius of the piezoelectric material layer were varied and transmitting performance were compared and analysed. From this simulation, the transmitting performance of the Piezoelectric Micro Ultrasonic Transducer (PMUT) is decreased as the membrane radius increased, while it increased as the thickness of the piezoelectric material layer increased. The total device thickness at 430 μm with the membrane radius at 1500 μm, show the best performance at 240 kHz of frequency, tailored for many underwater applications. The thickness and radius have contributed significantly to the mechanical stress generated at the surface of the piezoelectric material layer, in contact with the electrode. Hence, the device radius and thickness of the piezoelectric layer are considered,regardless of the type of piezoelectric material used

Enhancement of piezoelectric micromachined ultrasonic transducer using polymer membrane for underwater applications

533-539An effort to enhance receiving response of piezoelectric micromachined ultrasonic transducers (pMUT) at low frequency was reported. PMUTs were fabricated with the vibrating membrane formed by a layer of polydimethylsiloxane (PDMS) polymer. Lead zirconate titanate, Pd (Zt,Ti)O3 (PZT) was utilized as the piezo-active layer, sputtered with nickel electrodes. Spin coating and low temperature wafer bonding were proposed as part of the key fabrication methods. Fabricated transducers were characterized in the compact acoustic tank setup using 500 kHz and 1.25 MHz reference projectors. Analyses revealed the maximum receiving response was -36.6 dB re 1V of 200 kHz burst at 10 λ hydrophone-projector separations and 20 V peak to peak of drive voltage on reference projector. Finally, response spectrum of the transducer was plotted against two commercialized bulk hydrophones at equivalent frequency band for validation and comparison