Submitted by W. FUSHCHYCH Received November 25, 1995 Abstract An analytical method to study the effect of viscosity of a medium and the wave number on sound propagation and sound attenuation numbers in circular ducts has been presented. The method is based on the variation of parameters of the solution corresponding to the case of inviscid acoustic waves in circular ducts and axisymmetric modes...

A two-dimensional analytical solution is developed to determine the acoustic performance of a perforated single-pass, concentric cylindrical silencer filled with fibrous material. To account for the wave propagation through absorbing fiber and perforations, the complex characteristic impedance, wave number, and perforation impedance are employed. With expressions for the eigenvalues and eigenfu...

Application of the newly emerged space-time conservation element solution element (CESE) method to compressible Navier-Stokes equations is studied. In contrast to Euler equations solvers, several issues such as boundary conditions, numerical dissipation, and grid stiffness warrant systematic investigations and validations. Non-reflecting boundary conditions applied at the truncated boundary are...

page 156 Abstract: Already proven in a wide array of industrial applications, surface acoustic wave devices (SAWs) also have been demonstrated to hold substantial potential in the biosensor arena. Currently, SAW resonators coated with a biolayer can distinguish specific biomolecules in both liquid and vapor phases. By incorporating periodic perturbations in the design of SAW delay line, we were...

The method of Acoustic Wavefield Imaging (AWI) offers many advantages over conventional ultrasonic techniques for nondestructive evaluation, and also provides a means of incorporating fixed ultrasonic sensors used for structural health monitoring into subsequent inspections. AWI utilizes these fixed sensors as wave sources and an externally scanned ultrasonic transducer (or laser interferometer...

Robot audition system can greatly improve the adaptability of mobile robots especially in the case of robot vision system can’t work effectively. So an acoustic localization system using microphone array for mobile robot is proposed in this paper. In order to localize the sound source target, the microphone array used in the system consists of four microphones which were placed respectively on ...

Anisotropic density-near-zero (ADNZ) acoustic metamaterials are investigated theoretically and numerically in this paper and are shown to exhibit extraordinary transmission enhancement when material loss is induced. The enhanced transmission is due to the enhanced propagating and evanescent wave modes inside the ADNZ medium thanks to the interplay of near-zero density, material loss, and high w...