The variable thickness annular radial piezoelectric ultrasonic transducer can realize impedance transformation and energy concentration, has the advantages of large radiation area full directivity, is widely used in power ultrasound, underwater acoustic other fields. Because solving complex metal ring vibration wave equation more difficult, this paper, rings with transformed into superposition ...

Stimulated Raman backscattering (SRS) has many unwanted effects in megajoule-scale inertially confined fusion (ICF) plasmas. Moreover, attempts to harness SRS to amplify short laser pulses through backward Raman amplification have achieved limited success. In high-temperature fusion plasmas, SRS usually occurs in a kinetic regime where the nonlinear response of the Langmuir wave to the laser dr...

In this experimental study, acoustic receptivity was examined for a Blasius boundary layer formed on a flat plate. Non-localized surface roughness, 2-D and oblique, were considered for various roughness heights and acoustic wave amplitudes. The receptivity sites (surface roughness) had a well defined wavenumber spectrum with a fundamental wavenumber of kw. A planar downstream-traveling acoustic...

The applications are to Cymbal and Tonpilz transducer arrays for 3 50 kHz sonars, thin/thick film transducers for 10 100 MHz medical acoustic devices, underwater intensity sensors for lowfrequency surveillance, and flexural amplification mechanisms of the solid state strain for air acoustic transduction. Modeling and computer simulations of domain motions and structural vibrations and supportin...

A combination of borehole Stoneley waves from full waveform acoustic logs and direct shear wave logs was used to estimate formation permeability and shear wave velocity. Data sets used here were collected by ARea's array full waveform acoustic logging tool and shear wave logging tool. The Pand S-wave velocities of the formation are determined by threshold detection with cross-correlation correc...

Locating the trajectory of an incoming projectile has important military and civilian applications. The origin of the trajectory can be used to locate sniper fire, and the end-point can be used to determine target hit coordinates on appropriately instrumented target ranges used by armed forces as well as civilian agencies (police and sports). Such non-contact determination of hit coordinates ca...

This paper investigates the effects of a porous wall on development Tollmien–Schlichting (TS) waves propagating inside boundary layer. An experimental study performed in low-speed wind tunnel showed that microperforated panels over hollow chambers could promote laminar–turbulent transition. First, measurements streamwise evolution TS instabilities reveal greater amplification occurs perforated ...

We demonstrate heterodyne mixing of a 94 GHz millimetre wave photonic signal, supplied by a Gunn diode oscillator, with coherent acoustic waves of frequency ~100 GHz, generated by pulsed laser excitation of a semiconductor surface. The mixing takes place in a millimetre wave Schottky diode, and the intermediate frequency electrical signal is in the 1-12 GHz range. The mixing process preserves a...

This paper studies the propagation of shear waves in a composite structure consisting of a piezoelectric layer perfectly bonded over a micropolar elastic half space. The general dispersion equations for the existence of shear waves are obtained analytically in the closed form. Some particular cases have been discussed and in one special case the relation obtained is in agreement with existing r...

The propagation of arbitrary amplitude dust ion acoustic waves (DIAWs) in a magnetized collisional dusty plasma including hot electrons, with kappa velocity distribution for electrons, warm ions and dust particles has been studied. In the presence of immobile massive dust particulates, DIAWs have been investigated through the Sagdeev pseudo-potential method. It is demonstrated that the amplitud...