A novel type of half-concaved LiNbO(3) plate with domain inversion layer has been proposed for fabricating high-frequency broadband ultrasonic transducers. Two opposite ferroelectric polarization layers with a curved boundary are presented after heat treatment in the half-concaved LiNbO(3) plate with a total thickness of 110 μm. Characterization of the transducers illustrates that, without a ma...

This paper proposes a virtual reference feedback tuning (VRFT) method that can compensate for a dead zone. To this end, first, by focusing on the control error, we modify the performance index such that it is minimized in VRFT. Then, we present analysis results pertaining to the optimality conditions and their related filters in the modified VRFT method. Next, a VRFT method with dead-zone compe...

Transcranial focused ultrasound is a promising therapeutic modality. It consists of placing transducers around the skull and emitting shaped ultrasound waves that propagate through the skull and then concentrate on one particular location within the brain. However, the skull bone is known to distort the ultrasound beam. In order to compensate for such distortions, a number of techniques have be...

According to European Standard EN 1712 ultrasonic testing of thin-walled welded joints is mandatory for wall thicknesses of more than 8 mm only. Any thinner components do have to undergo X-ray inspection. Besides various advantages of X-ray testing viz. high sensitivity to smallest inclusions, high acceptance in the ship building sector and “automatic” documentation of inspection results, there...

We report on (to our knowledge) the first remote contactless photoacoustic measurements on semitransparent polymer samples. Samples consisting of a semitransparent polymer surface, black silicon glue and cast resin were produced. Measurements were done by illuminating the samples with short electromagnetic pulses of infrared radiation and detecting the generated ultrasound waves with a Fabry-Pé...

The nonlinear rheological response of soft glassy materials is addressed experimentally by focusing on concentrated emulsions where interdroplet attraction is tuned through varying the surfactant content. Velocity profiles are recorded using ultrasonic velocimetry simultaneously to global rheological data in the Couette geometry. Our data show that nonadhesive and adhesive emulsions have radica...

This contribution provides fundamental support, and both experimental and numerical wave propagation results demonstrating the ability to use a scalar source, a three component detector and the reciprocal TR process to selectively focus different vector components, either individually or collectively. The principle is explained from an analytical point of view, and the numerical and experimenta...

The paper shows how the precise knowledge of the sound field of an ultrasonic annular array can contribute to the development of novel measurement techniques. Emphasis is placed on (a) a non-invasive method for sound velocity measurements in fluids using the echo signals from scattering p]articles, (b) a non-invasive method for the combined determination of thickness and sound velocity in layer...

Currently, researchers are mainly focusing the phase transitions, domain structures, domain wall functionalities, magneto electric coupling, and the potential applications in high-density ferroelectric non-volatile memories of ferroelectric materials [1-5]. However, there are relatively less research interests in the biomedical applications of ferroelectric materials which is very important to ...

The multi-layer welding structure is a kind of important weld component used in modern aviation industry. In order to control the quality of the inner welds, the method of ultrasonic immersion testing with focusing probe has been performed in this study. Some testing signals displayed in the screen are overlapping signals composed by the echoes with different propagation routes in the multi-lay...