The innovative non-invasive intracranial volume wave monitor has been developed in Telematics Scientific Laboratory of Kaunas University of Technology (Lithuania). It is based on the measurement of the human brain parenchyma acoustic properties (ultrasound speed and attenuation) using time-of-flight technique [1,2] and it is capable of measuring different types of intracranial volume wave (slow...

A line-focus ultrasonic SH-wave probe is developed for possible application to TOFD method. The probe is composed of a quarteror half-cylindrical wedge and a piezoelectric transducer adhered to the cylindrical surface of the wedge. An SH-wave pulse with cylindrical wave front is generated by the transducer, transmitted to the wedge, and focused on a line at the bottom surface of the wedge. Henc...

Ultrasonic sensors are commonly used in robotics for range measurement in obstacle detection and avoidance systems. They have also been used for localization by map matching techniques. This paper presents a novel use of ultrasonic sensors for the measurement of angular position of a mobile robot relative to a known ultrasonic source. The method is based on measurement of the phase difference o...

The study of asymmetrical patterns of the light diffracted by ultrasonic waves has been utilized in the last decades to investigate ultrasonic wave distortions caused by the nonlinearity of the medium. In contrast to the investigation of diffraction patterns in space, a novel optical method is proposed in this work to analyze, in the frequency domain, the phase modulation (related to the Raman-...

Continuous-wave ultrasonic modulation of scattered laser light was used to image objects buried in tissue-simulating turbid media. The buried object had an absorption coefficient greater than the background turbid medium. The ultrasonic wave that was focused into the turbid media modulated the laser light that passed through the ultrasonic field. The modulated laser light that was collected by ...

Two ultrasonic nondestructive evaluation methods have been applied to systematically characterize the mechanical properties of nanostructured physical vapor deposited diamond-like carbon (DLC) ultra-hard coatings. A photoacoustic guided-wave technique is used to generate broadband surface acoustic waves (SAW) on the coating surfaces, and dispersion relations of the SAW for DLC coatings are meas...

This contribution describes a computationally efficient ray tracing algorithm for evaluating transducer generated ultrasonic wave fields in anisotropic materials such as austenitic cladded and austenitic weld components. According to this algorithm, ray paths are traced during its propagation through various layers of the material and at each interface the problem of reflection and transmission...

We present results of the theoretical description of ultrasonic phenomena in molecular liquids. In particular, we are interested in the development of a microscopical, i.e., statistical-mechanical, framework capable of explaining the long living puzzle of excess ultrasonic absorption in liquids. Typically, an ultrasonic wave in a liquid can be generated by applying a periodically alternating ex...

The ultrasonic propagation in the water-based magnetic fluid with doubled layered surfactant shell was studied. The measurements were carried out both in the presence as well as in the absence of the external magnetic field. The thickness of the surfactant shell was evaluated by comparing the mean size of magnetic grain extracted from magnetization curve with the mean hydrodynamic diameter obta...

The overall objective of the DARPA Structural Integrity Prognosis System (SIPS) program is to develop technologies to advance material damage state condition assessment with limited or no dedicated maintenance action. As a part of the sensors thrust area, an in situ ultrasonic sensing method was developed and demonstrated to detect cracks initiating from fastener holes and provide an estimate o...