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Research on active control for sound transmission with double panel systems showed that the use of control inputs to the radiating panel results in greater transmission loss. Further, having a stiff radiating panel in a double panel system increases the overall attenuation, and a controlled radiation panel excites on-resonance. These results indicate that double panel behavior can be used to improve control performance.

Disturbance increase enhancement in an acoustically excited jet depends on the angle of incidence of the sound and attains a maxima when the sound phase velocity becomes comparable to the disturbance propagation velocity. An ambient sound wave angle of propagation velocity initiates shock waves over the disturbances and moves along with them. Sound interactions with supersonic jets occur close to the nozzle exit without affecting the developed disturbances.

Compressibility propagates caustic waves from a high frequency point source in a rigid plate-overflowing wall shear layer. Mobile point sources sweep back caustic surfaces and localize the acoustic field energy on caustic surfaces. Mobile caustic surfaces are similar to laminar coherent fluid complexes that contain high vorticity values and explode to eject fluids, causing turbulence in the boundary layer.

The transfer matrix method was used to analyze the propagation of acoustic waves in multilayered anisotropic piezoelectric plates. This technique was also applied to the study of zinc oxide on silicon thin film resonators. The transfer matrix method, which was the physical equivalent of the transmission line analysis, was based on the principles of mechanisms rather than on electric circuit analysis.

Head-on blade-vortex interaction affects leading edge aerodynamics strongly due to the large intersection area. Holographic interferometry and Navier-Stokes equations reveal the pressure of opposing pressure peaks close to the air foil leading edge and predict sound wave propagation. The relaxation of pressure peaks to low pressure regions causes the propagation of a sound wave.

The effect of refraction by a flow boundary layer on the radiation of sound from a bending wave on a plate is investigated. Based on the relative velocities of the bending wave and the flow, four qualitatively different regimes are identified and results of numerical studies of radiation impedance and power emission are presented and discussed. For comparison, the role of a visco-thermal boundary layer is included with a correction of a numerical error in a previous paper.

The direct boundary integral equation due to Burton and Miller (1971) is used for the solution of the Helmholtz equation in the exterior domain. The formulation is complex, involving four integral (pseudo-differential) operators. Here we show that it is possible and advantageous to choose the coupling parameter, eta, inherent in the formulation, to depend on the boundary points. By setting the coupling parameter, eta (p), to zero, over the large part of the surface, we are able to reduce the set up time without greatly affecting the conditioning of the equation.

A unique 'postmortem' tool for evaluating crack velocity in brittle materials is explained by Wallner lines. A simple accurate method to analyze Wallner lines is observed and the method is based on first principle and yields in addition to crack velocity, also the velocity in which the information about crack initiation moved up to the Wallner line origin.

Helioseismological studies show that sound rays propagate deeper into the Sun than previously believed. These findings suggest that the Sun can be sampled at different depths by measuring the mean travel time of sound waves near the sunspots.

Nonuniform magnetic interactions excite acoustic waves in frequency range 4-12 gHz causing sharp distortions in the spin wave resonance spectrum of nonuniform yttrium iron garnet (YIG) films. Relative phase velocity of transverse acoustic waves and spin waves transforms the magnetic YIG system to an elastic system.

The spectral finite element methodology is employed to explain the mechanisms involved in the ultrasound guided waves propagation taking place in the layered viscoelastic film/substrate materials. The surface normal displacement and propagating characteristic of the system are shown to be highly dependent on the material parameters of the film.

Membrane-type acoustic metamaterials are prepared and analyzed to understand their acoustic response. The mechanisms responsible for the transmission loss (TL) peak are understood by mapping the out-of-plane dynamic response of the structure under acoustic loading at discrete frequencies.

A new method is described for controlling the thermoacoustic amplification in thermoacoustic engines. The studies have shown that below the onset of thermoacoustic instability, an optimum phase shift is present between the auxiliary sources that have maximized the acoustic power available in the annular waveguide.

A hybrid mode in ZnO solidly mounted resonator (SMR) devices is described. The performance of the device is simulated by using COMSOL platform, the eigenfrequencies of the structure is examined and a hybrid mode is found that is trapped both vertically and laterally in the ZnO film.

A method is developed that is based on the diffraction of acoustic waves by a rigid-frame, air-saturated polymeric foam in cylindrical foam in the audible frequency regime. The analytical solution equation of the scattered field has shown that it is dependent on the intrinsic microstructural parameters of the porous cylinder, including porosity, tortuosity, and the flow resistivity.

Several studies are conducted for the development of a new analytical theory, which is used for explaining the resonant sound transmission taking place through the small apertures on the periodically perforated slabs. The aperture resonance of the systems is shown to be completely dependent on the singularity of the diffraction induced reactance exhibited by them.

Propagation of 143 KHz ultrasound through an atmospheric pressure glow discharge in air is analyzed. The results have shown that sound attenuation has not depended on the thickness of the plasma and attenuation is caused by reflection of the sound waves from the plasma due to the sharp gas temperatures gradients that form at the plasma boundary.

Several theoretical, as well as experimental studies are conducted to explain the different evanescent modes that are exhibited by the sonic crystals (SCs). The application of the plane wave expansion and other [omega](k) methods for determining the band structures of the system is also demonstrated.

Several studies are conducted to explain the propagation of the spherical and cylindrical imploding and exploding shock waves exhibited in the different plasma systems. The shock structure and propagation are shown to be highly dependent on the positron concentration and kinematic viscosity.

The article explains the various mechanisms that are involved in the generation of the inhomogeneous bulk acoustic modes by the laser-induced thermoelastic grating process. The evanescent and the propagating nature of the two discussed modes of the system are also analyzed.

The article presents a detailed explanation of the various dual-mode thin film bulk acoustic resonators, which are shown to be based on the polar c-axis tilted wurtzite gallium nitride. These resonators are shown to be widely used in a large number of frequency control device design and applications.

Several studies are conducted to explain the process involved in the Brillouin shifted third harmonic generation of an intense laser of finite spot size in a plasma. The second harmonic ponderomotive force exerted by the laser on the electrons is also analyzed.

The localized vibrational modes are considered that can exist at the edge of a semi-infinite plate at the end of a semi-infinite bar of small thickness. The effect of the localization phenomenon on the vibrational modes of plates and bars of finite length is discussed.

Byline: Shoudong Wang Computed tomography technology has been widely applied in many fields such as geographical structure detection, industrial detection and clinical diagnosis. In some situations the image quality is not high due to the measurement errors and disturbances. In this paper, a topographic method is studied using an acoustic wave equation to describe the propagation of the wave. Both forward modelling and image processing are performed in frequency domain to reach higher accuracy. The images are reconstructed using not only travel time but also the signal waveform to reduce errors and noise. The method has the potential of being used in clinical diagnostic ultrasound imaging.

Fluid motion induced on the surface of 100 MHz focused surface acoustic wave (F-SAW) devices with concentric interdigital transducers (IDTs) based on Y-cut Z-propagating LiNb[O.sub.3] substrate is examined by using three-dimensional bidirectionally coupled finite element fluid-structure interaction models. The results have shown a technique of enhancing streaming induced flows, which is important to contemporary problems involving microfluidic and sensing applications of piezoelectric devices.

The shock Hugoniot of single copper is described for stresses below 66 GPa and symmetric impact experiments are used for measuring the Hugoniots of three different crystal orientations. The studies have shown that at the lowest stresses, the sound speed in Cu is extracted from the photonic doppler velocimetry (PDV) data.

Acoustic levitation was employed to study the multiple-lobed shape bifurcations of rotating drops and the evolution of the four-lobed equilibrium shape. The results confirmed the existence of bifurcation point shifts among all the lobed-shape families due to the initial drop flattening induced by the acoustic radiation pressure, which plays a decisive role in the emergence of the five-lobed shape.

The deformation of the liquid surface under acoustic radiation pressure are considered to theoretically study the interaction of acoustic levitation field with liquid reflecting surface. The liquid reflectors with larger surface tension and higher density are found to behave closely to the planar rigid reflector.

A brief history of the origin of the fourth-power law which relates the stress jump through a steady structured shock wave and the maximum strain rate within the shock wave is presented. The observations of systematic behaviors with component cell size and impedance disparities suggested the possible contribution of acoustic scattering to wave structuring in selected materials.

A model is developed to describe experimental data of mechanical losses in a a round quartz plate with the diameter 7.48 cm and the thickness 1.2 cm at temperatures 5-25 K in the range of eigenfrequencies 11-300 kHz. The model is able to account for both the contribution of thermoelastic losses and the contribution due to the interaction of the acoustic wave with thermal phonons (Akhieser damping).

The impulsive stimulated thermal scattering (ISTS) method is used for determining the second-order elastic constants for cyclotetramethylene tertanitramine ([beta]-HMX) single crystals. The results have shown the efficiency of the ISTS method for determining the full set of elastic constants of low-symmetry molecular crystals.

Several spectroscopic time-resolved high-energy x-ray diffraction measurements are conducted to study the laser-induced shock and acoustic waves being generated in single crystalline silicon. The propagation of the wave is shown to be highly dependent on the sample geometry of the crystal.

The article explains the imaging setup of a new technology, which can be easily used for the detection and imaging of a target in a strongly scattering medium. The matrix approach employed in the technique is shown to be extremely effective, as it can help in the reduction of aberrations induced in a heterogeneous layer.

Several studies are conducted to explain the various acousto-optic (AO) effects in the photonic crystals (PCs) containing defects. The different acoustic wavelengths are shown to lead to different synchronized and desynchronized modulations in a dual-defect situation in these crystals.

The experimental evidence for the relationship between the generation of leaky Rayleigh waves and the formation of the two reflected lobes and a null strip for bounded beam incidence at the Rayleigh angle is reported. The evidence based on an experimental setup using a sound barrier on a liquid solid interface offer insight into the influence of the bonding properties between the barrier and the solid on the observed radiation patterns which have great significance to the nondestructive characterization of bonding in general.

Analytical and numerical approaches are used for analyzing the behavior of guided waves (Lamb-types waves) propagating inside plates with a rough surface, which is considered as distributed small perturbations. The results on periodically corrugated surfaces of fluid plates have emphasized the role played by the spatial period and the modal coupling.

Short pulsed laser induced single acoustic wave generation, propagation, interaction with rigid structures and focusing in water are analyzed. The results have shown that the laser induced planar acoustic wave can be focused down to several tons of micron size and several bars in pressure.

The propagation and the generation of leaky surface acoustic waves (SAW) are studied in a fluid layer enclosed between the half-infinite YZ-LiNb[O.sub.3] (lithium niobate) substrate coated with a thin Si[O.sub.2] (silicone dioxide) layer and the half-infinite domain occupied by silicone rubber. The results obtained revealed that an interdigital transducer (IDT) is able to efficiently generate acoustic waves in fluid layers up to several wavelengths thick.

The design of a polymer composites reinforced by carbon nanofibers (CNFs) in the form of paper sheet with significantly improved vibration and acoustic damping is reported. The results from the analysis of acoustic wave propagation provide insight into the effects of acoustic impedance discontinuity at the interfaces of the layered structure.

The design and development of one-dimensional model for sound propagation in glow discharge plasma to arbitrary mutual orientation of the plasma electric field and acoustic wave vectors is reported. The results showed that an acoustic wave in plasma might amplify, attenuate, or remain unchanged depending on the angle between vectors and on the power input into the discharge.

A new molecular dynamics simulation approach is presented for visualizing multi-dimensional acoustic wave packet propagation in anisotropic materials. The approach allows examination of longitudinal wave propagation in a selected frequency range and also extended to track transverse motions.

The boundary waves propagating along the substrate with the structure of multithin film layers/metal electrode/piezoelectric substrate are analyzed by using high velocity thin film. The results of surface acoustic wave resonators have displayed good frequency response of admittance at 500 MHz range.

A finite difference time-domain analysis was used to perform a numerical study to determine the impact of periodic fractal-shaped inclusions on the frequency response of two-dimensional phononic or acoustic band gap crystals. The results obtained for the phenomenon in periodic fractal inclusion acoustic band gap crystals could be applied for miniaturization of filters or other devices and structures that exploit acoustic band gap principles.

The nonlocal elastic theory is used for analyzing the effects of flow velocity on the vibration frequency and mode shape of the fluid-conveying frequency and carbon nanotube. The results have shown that the frequency and mode shape are influenced by the nonlocal parameter, where the mode shape of the combination has increased with the increase in nonlocal effect.