Till recently it was considered that velocity of piezoactive acoustic waves propagating in piezoelectric materials decreases at total or partial switching off of piezoeffect. However, recently there appear publications showing that there are such materials and crystallographic orientations for which the velocity of bulk as well as surface acoustic waves in presence of piezoeffect (vpz) may be l...

The problem of forced acoustic oscillations in a pipe is studied theoretically. The oscillations are produced by a moving piston in one end of the pipe, while a variety of boundary conditions ranging from a completely closed to a completely open mouth at the other end are considered. All these boundary conditions are modelled by two parameters: a length correction and a reflexion coefficient eq...

acoustic neuromas (an) are schwann cell-derived tumors that commonly arise from the vestibular portion of the eighth cranial nerve also known as vestibular schwannoma(vs) causes unilateral hearing loss, tinnitus, vertigo and unsteadiness. in many cases, the tumor size may remain unchanged for many years following diagnosis, which is typically made by mri. in the majority of cases the tumor is s...

The ultrasonic attenuation is evaluated at 300 K along [100], [110], and [111] directions for the characterization of bcc metal Ta. The size of the metal is considered in nanorange. Ultrasonic velocity, Grüneisen parameter and acoustic coupling constant that depend on second and third order elastic constants are calculated for determination of ultrasonic attenuation coefficient. Second and thir...

We investigate the viscoelastic properties of confined molecular nano-layers by time resolved optical pump-probe measurements. Access to the elastic properties is provided by the damping time of acoustic eigenmodes of thin metal films deposited on the molecular nano-layers which show a strong dependence on the molecular layer thickness and on the acoustic eigen-mode frequencies. An analytical m...

diesel exhaust particles are a complex mixture of thousands of gases and fine substances that contain more than 40 different environmental contaminants. being exposed to these exhaust particles (called soot) can cause lung damage and respiratory problems. diesel particulate filters are used in many countries for mobile sources as a legal obligation to decrease harmful effect of these fine parti...

Introduction: MR-guided focused ultrasound surgery (MRgFUS) is a non-invasive means of causing selective tissue necrosis using high-power ultrasound and MR temperature imaging (MRTI). Predicting the power deposition pattern in the inhomogeneous tissue requires a beam propagation technique that has the ability to handle inhomogeneous acoustic properties. Beyond the innate inhomogeneities of tiss...