Matched Gaussian Apodization of Pulsed Acoustic Phased Arrays

1980 ◽  
Vol 2 (4) ◽  
pp. 338-369 ◽  
Author(s):  
Andre J. Duerinckx
Keyword(s):  
Cross Section ◽  
Phased Array ◽  
Phased Arrays ◽  
Near Field ◽  
Homogeneous Medium ◽  
Short Pulses ◽  
Time Space ◽  
Acoustic Beams ◽  
Strong Focusing ◽  
Matching Concept

Gaussian apodization weighting functions matched to the time delay distribution for focusing of phased arrays are introduced. The matching concept is based upon the theory of eigenmodes of freely propagating acoustic beams with a finite cross-section. The effect of this matched gaussian apodization on the beam cross-section is analysed for several acoustic phased array configurations generating acoustic wavefronts in a weakly attenuating and homogeneous medium. A strength of focusing parameter is introduced. The relation between apodization parameters and the strength of focusing is analyzed and illustrated. For strong focusing the parameters of the gaussian matched apodization become independent of the focal range. A simulator was developed which allows the study of acoustic pressure waves in the near-field and far-field generated by a linear phased array excited with short pulses. The simulator provides 2-D and 3-D representations of acoustic wave fronts generated by a pulsed phased array, illustrating the effects of apodization for pulsed acoustic beams in the time-space domain.

scholarly journals Ultrasonic Imaging of Thick Carbon Fiber Reinforced Polymers through Pulse-Compression-Based Phased Array

2021 ◽  
Vol 11 (4) ◽  
pp. 1508
Author(s):  
Muhammad Khalid Rizwan ◽  
Stefano Laureti ◽  
Hubert Mooshofer ◽  
Matthias Goldammer ◽  
Marco Ricci
Keyword(s):  
Carbon Fiber ◽  
Pulse Compression ◽  
Phased Array ◽  
Signal To Noise Ratio ◽  
Near Field ◽  
Ultrasonic Imaging ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Custom Made ◽  
Carbon Fiber Reinforced

The use of pulse-compression in ultrasonic non-destructive testing has assured, in various applications, a significant improvement in the signal-to-noise ratio. In this work, the technique is combined with linear phased array to improve the sensitivity and resolution in the ultrasonic imaging of highly attenuating and scattering materials. A series of tests were conducted on a 60 mm thick carbon fiber reinforced polymer benchmark sample with known defects using a custom-made pulse-compression-based phased array system. Sector scan and total focusing method images of the sample were obtained with the developed system and were compared with those reconstructed by using a commercial pulse-echo phased array system. While an almost identical sensitivity was found in the near field, the pulse-compression-based system surpassed the standard one in the far-field producing a more accurate imaging of the deepest defects and of the backwall of the sample.

scholarly journals Coalescence Dynamics of Acoustically Levitated Droplets

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 343 ◽  
Author(s):  
Koji Hasegawa ◽  
Ayumu Watanabe ◽  
Akiko Kaneko ◽  
Yutaka Abe
Keyword(s):  
Sound Pressure ◽  
Phased Array ◽  
Phased Arrays ◽  
Industrial Applications ◽  
Acoustic Levitation ◽  
Droplet Dynamics ◽  
Levitated Droplets ◽  
Ultrasonic Phased Array ◽  
Velocity Information ◽  
The Impact

The contactless coalescence of a droplet is of paramount importance for physical and industrial applications. This paper describes a coalescence method to be used mid-air via acoustic levitation using an ultrasonic phased array system. Acoustic levitation using ultrasonic phased arrays provides promising lab-on-a-drop applications, such as transportation, coalescence, mixing, separation, evaporation, and extraction in a continuous operation. The mechanism of droplet coalescence in mid-air may be better understood by experimentally and numerically exploring the droplet dynamics immediately before the coalescence. In this study, water droplets were experimentally levitated, transported, and coalesced by controlled acoustic fields. We observed that the edges of droplets deformed and attracted each other immediately before the coalescence. Through image processing, the radii of curvature of the droplets were quantified and the pressure difference between the inside and outside a droplet was simulated to obtain the pressure and velocity information on the droplet’s surface. The results revealed that the sound pressure acting on the droplet clearly decreased before the impact of the droplets. This pressure on the droplets was quantitatively analyzed from the experimental data. Our experimental and numerical results provide deeper physical insights into contactless droplet manipulation for futuristic lab-on-a-drop applications.

scholarly journals On development of a technique for estimating structural dynamics and strength of modular phased array

2017 ◽  
pp. 75-82
Author(s):  
V. G. Lisovskiy ◽  
E. N. Khmelnitskiy ◽  
A. V. Kuzmicheva
Keyword(s):  
Structural Dynamics ◽  
Phased Array ◽  
Phased Arrays ◽  
Dynamic Environment ◽  
Vibration Acceleration ◽  
Transmission Coefficients ◽  
Mechanical Factors ◽  
Strain Stress ◽  
The Individual ◽  
Stiffening Effect

The purpose of the study was to develop a method of computational and experimental analysis to reduce the dimension of the problem, which makes it possible to simplify and accelerate the strength calculations. When using the method, one can take into account the stiffening effect of the carrier object, where the product will be installed, determine the transmission coefficients of vibration acceleration from the base of the structure to the individual units of the equipment to assess their strength and stability under the influence of mechanical factors. Moreover, the method allows for the strain-stress state analysis using the dynamic environment coefficients. Currently, the developed method is used in the design of several promising projects using modular phased arrays, both sea and land-based

scholarly journals Near-Field Rx-Measurement for Active Phased Array of Digital Radar Using Calibration Path

2016 ◽  
Vol 27 (6) ◽  
pp. 504-511 ◽  
Author(s):  
Je-Woo Yu ◽  
Heeduck Chae ◽  
Jongkuk Park ◽  
Jae-Hwan Lim ◽  
Duckhwan Kim ◽  
...  
Keyword(s):  
Phased Array ◽  
Near Field

scholarly journals EFFICIENT SIMULATION TOOL TO CHARACTERIZE THE RADAR CROSS SECTION OF A PEDESTRIAN IN NEAR FIELD

2020 ◽  
Vol 100 ◽  
pp. 145-159
Author(s):  
Giovanni Manfredi ◽  
Paola Russo ◽  
Alfredo De Leo ◽  
Graziano Cerri
Keyword(s):  
Cross Section ◽  
Near Field ◽  
Radar Cross Section ◽  
Simulation Tool ◽  
Efficient Simulation
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