scholarly journals Orthogonal Chirp Coded Excitation in a Capacitive Micro-machined Ultrasonic Transducer Array for Ultrasound Imaging: A Feasibility Study

Sensors ◽  
2019 ◽  
Vol 19 (4) ◽  
pp. 883
Author(s):  
Bae-Hyung Kim ◽  
Seungheun Lee ◽  
Kang-Sik Kim
Keyword(s):  
Feasibility Study ◽  
Ultrasonic Transducer ◽  
Low Frequency ◽  
Beam Width ◽  
Ultrasonic Transducers ◽  
Experimental Result ◽  
Frequency Bandwidth ◽  
Coded Excitation ◽  
Short Pulses ◽  
Bandwidth Characteristic

It has been reported that the frequency bandwidth of capacitive micro-machined ultrasonic transducers (CMUTs) is relatively broader than that of other ceramic-based conventional ultrasonic transducers. In this paper, a feasibility study for orthogonal chirp coded excitation to efficiently make use of the wide bandwidth characteristic of CMUT array is presented. The experimental result shows that the two orthogonal chirps mixed and simultaneously fired in CMUT array can be perfectly separated in decoding process of the received echo signal without sacrificing the frequency bandwidth each chirp. The experimental study also shows that frequency band-divided orthogonal chirps are successfully compressed to two short pulses having the −6 dB axial beam-width of 0.26- and 0.31-micro second for high frequency and low frequency chirp, respectively. B-mode image simulations are performed using Field II to estimate the improvement of image quality assuming that the orthogonal chirps designed for the experiments are used for simultaneous transmission multiple-zone focusing (STMF) technique. The simulation results show that the STMF technique used in CMUT array can improve the lateral resolution up to 77.1% and the contrast resolution up to 74.7%, respectively. It is shown that the penetration depth also increases by more than 3 cm.

scholarly journals Development of Broadband High-Frequency Piezoelectric Micromachined Ultrasonic Transducer Array

Sensors ◽  
2021 ◽  
Vol 21 (5) ◽  
pp. 1823
Author(s):  
Xu-Bo Wang ◽  
Le-Ming He ◽  
You-Cao Ma ◽  
Wen-Juan Liu ◽  
Wei-Jiang Xu ◽  
...  
Keyword(s):  
High Frequency ◽  
3D Imaging ◽  
Ultrasonic Transducer ◽  
Ultrasonic Transducers ◽  
Frequency Bandwidth ◽  
Half Wavelength ◽  
Acoustic Beams ◽  
Working Frequency ◽  
Sub Wavelength ◽  
2D Array

Piezoelectric micromachined ultrasonic transducers (PMUT) are promising elements to fabricate a two-dimensional (2D) array with a pitch small enough (approximately half wavelength) to form and receive arbitrary acoustic beams for medical imaging. However, PMUT arrays have so far failed to combine the wide, high-frequency bandwidth needed to achieve a high axial resolution. In this paper, a polydimethylsiloxane (PDMS) backing structure is introduced into the PMUTs to improve the device bandwidth while keeping a sub-wavelength (λ) pitch. We implement this backing on a 16 × 8 array with 75 µm pitch (3λ/4) with a 15 MHz working frequency. Adding the backing nearly doubles the bandwidth to 92% (−6 dB) and has little influence on the impulse response sensitivity. By widening the transducer bandwidth, this backing may enable using PMUT ultrasonic arrays for high-resolution 3D imaging.

scholarly journals A System in Package Based on a Piezoelectric Micromachined Ultrasonic Transducer Matrix for Ranging Applications

Sensors ◽  
2021 ◽  
Vol 21 (8) ◽  
pp. 2590
Author(s):  
Alexandre Robichaud ◽  
Dominic Deslandes ◽  
Paul-Vahé Cicek ◽  
Frederic Nabki
Keyword(s):  
High Voltage ◽  
Integrated Circuit ◽  
Ultrasonic Transducer ◽  
Ultrasonic Transducers ◽  
Transimpedance Amplifier ◽  
Measurement Results ◽  
Ultrasonic Ranging ◽  
High Voltage Pulser ◽  
Working Frequency ◽  
Simulation Results

This paper proposes a system in package (SiP) for ultrasonic ranging composed of a 4 × 8 matrix of piezoelectric micromachined ultrasonic transducers (PMUT) and an interface integrated circuit (IC). The PMUT matrix is fabricated using the PiezoMUMPS process and the IC is implemented in the AMS 0.35 µm technology. Simulation results for the PMUT are compared to the measurement results, and an equivalent circuit has been derived to allow a better approximation of the load of the PMUT on the IC. The control circuit is composed of a high-voltage pulser to drive the PMUT for transmission and of a transimpedance amplifier to amplify the received echo. The working frequency of the system is 1.5 MHz.

Manage the Risk of Turbine Rotor Failure

2010 ◽  
Author(s):  
David Yates ◽  
Angelo Tarantino ◽  
Joop Kraijesteijn
Keyword(s):  
Ultrasonic Transducer ◽  
Large Body ◽  
The United States ◽  
Turbine Rotor ◽  
Operational Reliability ◽  
Ultrasonic Transducers ◽  
Economic Costs ◽  
Utility Industry ◽  
Power Generation Equipment ◽  
Accepted Practice

Turbine rotors failure has resulted in a broad spectrum of events ranging from catastrophic burst to prolonged forced outages that ultimately have significant economic costs for affected utilities. Avoiding turbine rotor failure and its associated cost requires a detailed understanding of the operational reliability of power generation equipment. Nearly all large body turbine and generator rotors manufactured in the United States typically have a central bore hole that provides suitable access from which to conduct various material inspections. The term “boresonics” has become synonymous with the procedure for performing ultrasonic examination of turbine rotor material as conducted from the surface of a central bore cavity. Boresonics is now a fairly common and accepted practice throughout the utility industry. In general, boresonics involves passing ultrasonic transducers through the rotor bore to search a given volume of material for flaws at different locations and orientations within a rotor forging. Each individual ultrasonic transducer has specific inherent performance characteristics based on known wave physics that governs the art of ultrasonic testing. The results of boresonic inspections offer utility engineers a basis for making intelligent decisions on the condition of turbine and generator rotors. This paper describes how boresonic inspections are typically performed in the industry. Furthermore, the paper will give a description of the equipment and required skills of the system operators and will present examples of findings based on KEMA’s experience in this field.

Method for Modeling Ultrasonic Driving Circuit and Designing Matching Network

2012 ◽  
Vol 629 ◽  
pp. 682-687 ◽  
Author(s):  
Bo Xiong Wang ◽  
Wen Feng Liu ◽  
Jian Nan Liu ◽  
Yuan Yuan Cui ◽  
Xiu Zhia Luo
Keyword(s):  
Time Domain ◽  
Power Supply ◽  
Ultrasonic Testing ◽  
Ultrasonic Transducer ◽  
Ultrasonic Transducers ◽  
Matching Network ◽  
Matching Networks ◽  
Impedance Characteristics ◽  
Driving Circuit ◽  
Attenuation Characteristics

The performances of ultrasonic testing systems are greatly affected by the impedance characteristics of ultrasonic transducers. Conventional methods for designing matching networks consider only the characteristics of matching elements and transducer, while ignoring the effects of other elements of emission circuit. As a consequence, such method cannot give out satisfactory results. In this paper, a modeling method for ultrasonic driving circuits is proposed, which takes into account the power supply, the transformer, the matching networks, as well as the ultrasonic transducer. This method focuses on the performances both in time domain and in frequency domain. A computer simulation and experiments show that this method can provide better attenuation characteristics and energy transmission, and can be widely used for analyzing and designing matching network for ultrasonic testing systems.

Sub-array equalization technique for the parametric array loudspeaker to reduce nonlinear distortion

2021 ◽  
Vol 263 (5) ◽  
pp. 1497-1504
Author(s):  
Chi Zhang ◽  
Jing Ren ◽  
Chuang Shi
Keyword(s):  
Nonlinear Distortion ◽  
Ultrasonic Transducer ◽  
Previous Method ◽  
Ultrasonic Transducers ◽  
Acoustic Effect ◽  
The Past ◽  
Comparison Results ◽  
Equalization Technique ◽  
Nonlinear Acoustic ◽  
Parametric Array

The parametric array loudspeaker (PAL) is a directional loudspeaker which uses the nonlinear acoustic effect, namely the parametric array, to produce an audio beam from narrow ultrasonic beams. The PAL can efficiently deliver audible information, without generating noise to the surroundings. One significant drawback of the PAL is the nonlinear distortion. Therefore, many sophisticated methods have been proposed to preprocess the input signal of the PAL. However, those methods usually request a flat frequency response of the ultrasonic transducer array (UTA). In the past, equalization has been tried out for the whole UTA, but the performance was sometimes not satisfactory due to the inconsistent productions of ultrasonic transducers. This paper proposes to group the ultrasonic transducers by their impedances. Several sub-arrays are thereafter formed and equalized individually. The comparison results demonstrate that the propose sub-array equalization technique can suppress the nonlinear distortion of the PAL more effectively than the previous method.

Real-Time Vehicle License Plate Recognition Based on Scanning and 2D Haar Discrete Wavelet Transform

2013 ◽  
Vol 284-287 ◽  
pp. 2402-2406 ◽  
Author(s):  
Rong Choi Lee ◽  
King Chu Hung ◽  
Huan Sheng Wang
Keyword(s):  
Wavelet Transform ◽  
Discrete Wavelet Transform ◽  
Real Time ◽  
Recognition Rate ◽  
Low Frequency ◽  
Experimental Result ◽  
Discrete Wavelet ◽  
License Plate ◽  
License Plate Recognition ◽  
Image Pixels

This thesis is to approach license-plate recognition using 2D Haar Discrete Wavelet Transform (HDWT) and artificial neural network. This thesis consists of three main parts. The first part is to locate and extract the license-plate. The second part is to train the license-plate. The third part is to real time scan recognition. We select only after the second 2D Haar Discrete Wavelet Transform the image of low-frequency part, image pixels into one-sixteen, thus, reducing the image pixels and can increase rapid implementation of recognition and the computer memory. This method is to scan for car license plate recognition, without make recognition of the individual characters. The experimental result can be high recognition rate.

Covert Underwater Acoustic Communication System Using Parametric Array

2019 ◽  
Vol 53 (1) ◽  
pp. 20-26 ◽  
Author(s):  
Anbang Zhao ◽  
Yue Cheng ◽  
Tiansi An ◽  
Juan Hui
Keyword(s):  
Orthogonal Frequency Division Multiplexing ◽  
Low Frequency ◽  
Nonlinear Behavior ◽  
Beam Width ◽  
Point Of View ◽  
Underwater Acoustic Communication ◽  
Water Tank ◽  
Narrow Beam ◽  
Underwater Acoustic ◽  
Parametric Array

AbstractA novel and efficient covert underwater acoustic (UWA) communication scheme using an acoustic parametric array and orthogonal frequency division multiplexing (OFDM) system is presented. The proposed system is robust and can easily be implemented in the ocean environment. The system is also very useful in military applications where the secrecy of transmission signal and location of the transmitter are extremely important. The paper exploits the difference frequency generated by the acoustic parametric array due to the nonlinear behavior of an underwater medium. Besides the lightness and compactness, the parametric array also possesses the advantage of being low-frequency, broadband, highly directive, and narrow beam with no side lobes. The narrow beam width also helps to secure the data from a spatial point of view. Experiments have been performed in a water tank, and the results are presented to show the effectiveness of the proposed scheme.

scholarly journals Designing the ultrasonic system used in industrial air filtration based on the ultrasonic cavitation phenomenon

2019 ◽  
Vol 290 ◽  
pp. 11009
Author(s):  
Dan Niţoi ◽  
Zoia Apostolescu ◽  
Constantin Petriceanu ◽  
Corneliu Rontescu
Keyword(s):  
Ultrasonic Transducer ◽  
Ultrasonic Cavitation ◽  
Ultrasonic Transducers ◽  
Air Purification ◽  
Acoustic System ◽  
Purification Process ◽  
Air Filtration ◽  
Air Filter ◽  
Cavitation Phenomenon ◽  
Working Method

The paper presents the activity developed developed in the field of polluted air purification from industrial shop (paint shops, foundries, welding constructions, forging, etc.). The advantages of using ultrasounds in the pollutant air filtration and purification process and an ultrasonic filter designed are presented considering the ultrasonic cavitation phenomenon. The main computational and construction elements of the ultra-acoustic system used in the design of the air filter are presented in the paper. The work focuses in the design of the main part of the ultrasonic system represented by ultrasonic transducer. In this case, the transducer network that is used in ultrasonic cavitation method consists of ten ultrasonic transducers. Each one of them consists of asymmetrical passive elements (reflector and radiant element).The design steps and the use of FEM as working method will provide the theoretical basis of the operation of the ultrasonic system so that it allows air filtration based on the ultrasonic acoustic cavitation phenomenon.

scholarly journals AlN-on-Si Square Diaphragm Piezoelectric Micromachined Ultrasonic Transducer with Extended Range of Detection

Proceedings ◽  
2018 ◽  
Vol 2 (13) ◽  
pp. 913 ◽  
Author(s):  
Suresh Alasatri ◽  
Libor Rufer ◽  
Joshua En-Yuan Lee
Keyword(s):  
Printed Circuit Board ◽  
Ultrasonic Transducer ◽  
Ultrasonic Transducers ◽  
Circuit Board ◽  
Detection Range ◽  
Range Finding ◽  
Sensing Applications ◽  
Current State ◽  
Wire Bonds ◽  
Extended Range

We present aluminum nitride (AlN) on silicon (Si) CMOS-compatible piezoelectric micromachined ultrasonic transducers (pMUTs) with an extended detection range of up to 140 cm for touchless sensing applications. The reported performance surpasses the current state-of-art for AlN-based pMUTs in terms of the maximum range of detection using just a pair of pMUTs (as opposed to an array of pMUTs). The extended range of detection has been realized by using a larger diaphragm allowed by fabricating a thicker diaphragm than most other pMUTs reported to date. Using a pair of pMUTs, we experimentally demonstrate the capability of range-finding by correlating the time-of-flight (TOF) between the transmit (TX) and receive (RX) pulse. The results were obtained using an experimental setup where the MEMS chip was interconnected with a customized printed circuit board (PCB) using Al wire bonds.

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