An acousto-optical reconstruction method for acoustic signals using multidirectional light diffraction by finite amplitude ultrasonic pulses is presented. When crossing the ultrasonic field, the far field diffracted laser light intensity of an incident convergent lightbeam becomes modulated in time. It is found that for special conditions, concerning direction of observation, ultrasonic frequen...

Ultrasonic fields in glycerol are visualized by holographic interferometry with a phase-modulated reference beam. Fine particles suspended in glycerol are illuminated with sheetlike light, and the light scattered from the illuminated plane is recorded in a hologram. The ultrasonic field on the plane is displayed in the reconstructed image, which provides equiphase positions of the wave, i.e., w...

The paper is devoted to the experimental investigation of the statistical characteristics of the grid-generated turbulence produced in a wind tunnel. Ultrasonic time-of-flight method using dual transducers is utilized to develop a methodology for determination of the correlation functions of turbulent velocity and sound speed fluctuations. The ultrasonic flowmeter equation is considered in the ...

Traditional online wheel-set ultrasonic inspection method and inspection technology can not meet the new requirement of High Power Locomotive wheel-set online. In this article, features of locomotive wheel and defect distribution are analyzed, and a more strictly online inspection requirement is put forward. Based on which, an optimized multi arrangement of phased array and conventional ultraso...

This paper considers the detection of symmetric crack-like defects in thin metallic plates using longitudinal ultrasonic waves. Only physically small defect sizes are considered in order that the initial stages of crack growth, for example during fatigue, can be detected. This method has the potential to be significantly faster for non-destructively detecting defects than conventional ultrasoni...

Because of the serious non-linearity and coupling among state variables caused by the complex energy conversion process in ultrasonic motor, the motion control strategy of ultrasonic motor still need to be studied in detail to obtain better performance. As a kind of special control method, the low-frequency PWM control strategy can make the on-line optimum control easier, and may be an effectiv...

Matching pursuit is an iterative method whereby a signal is decomposed into a linear combination of functions that are selected from a redundant dictionary. In the original paper by Mallat and Zhang [1], a dictionary of Gabor functions is proposed. Each Gabor function is the product of a Gaussian function with a complex sinusoid, and is specified by time, frequency and scale. Since these functi...

Ultrasonic ranging is the most common method used in robotic systems for distance or proximity sensing. The heart of the method is an ultrasonic transducer that emits and detects ultrasound. There are mainly two types of transducers existing in the market today; piezoelectric and electrostatic. In this paper, we propose the use of a new type of transducer, which is capacitive micromachined ultr...

BACKGROUND The main goal of endodontic treatment is to achieve cleaning and shaping prior to the filling process. OBJECTIVE This study aimed to evaluate, using atomic absorption spectrometry, the release of Calcium ions after the use of different chelating agents and protocols of agitation. METHOD Ninety human canine teeth were randomly assigned to one of nine groups (n=10), as follows: 1) ...

The pulse compression technique is successfully and widely used in many fields for improving the signal to noise ratio (SNR); which is especially useful when the environment is noisy and the SNR is poor. Since high frequency ultrasound is strongly attenuated in concrete, only low frequency ultrasound can be used in ultrasonic nondestructive testing (NDT) of concrete. In this study the pulse com...