eveloping realistic tactile displays for virtual reality has been challenging. Tangible displays are increasingly important interfaces not only for augmenting the reality of computer graphics but also for conveying graphical information to persons with visual impairments. Researchers have used various actuators for displays such as miniature loud speakers , 1 a pin array, 2 pneumatic actuators,...

This paper describes the use of genetic algorithms (GAs) for the optimal design of phononic bandgaps in periodic elastic two-phase media. In particular, we link a GA with a computational finite element method for solving the acoustic wave equation, and find optimal designs for both metal–matrix composite systems consisting of Ti/SiC, and H2O-filled porous ceramic media, by maximizing the relati...

Techniques that can dexterously manipulate single particles, cells, and organisms are invaluable for many applications in biology, chemistry, engineering, and physics. Here, we demonstrate standing surface acoustic wave based "acoustic tweezers" that can trap and manipulate single microparticles, cells, and entire organisms (i.e., Caenorhabditis elegans) in a single-layer microfluidic chip. Our...

This tutorial will explain the pumping system speed of sound concept (how to account for acoustic velocity changes due to pipe wall flexibility and liquid properties), the definition of quarter-wave, half-wave, and higher order acoustic mode shapes, the importance of each mode shape, and examples of how to estimate these mode shapes and frequencies. The use of basic acoustics to identify and re...

In this paper we address a series of so-called local plane wave methods (LPW) to measure acoustic absorption. As opposed to other methods, these methods do not rely on assumptions of the global sound field, like e.g. a plane wave or diffuse field, but are based on a local plane wave assumption. Therefore, the LPW methods can be used for any given surface/absorbing material and any arbitrary sou...

The dust acoustic wave (DAW) is a very low frequency (tens of Hz) dust density wave in which the dust particles participate in the wave dynamics. The early experimental observations of DAWs showed that the wave was self-excited by a modest relative ion drift and grew to very high amplitudes (~100%). In the first part of this paper we describe experiments showing the self-steepening of nonlinear...

(Near-field Acoustic Holography, Audio Production, Guitar) In recording studios, the placement of microphones to record an acoustic guitar is very much subjected to trial and error and audio engineer preference. In order to make more informed microphone placement decisions, Near-field Acoustic Holography is used to study the sound pressures of the guitar. This technique involves solving the int...

The secondary wave field associated with undular tidal bores (known as whelps) has been barely studied in field conditions: the wave field can be strongly non-hydrostatic, and the turbidity is generally high. In situ measurements based on pressure or acoustic signals can therefore be limited or inadequate. The intermittent nature of this process in the field and the complications encountered in...

We demonstrate that the propagation of surface acoustic waves, arising from the excitation of the acoustic field on a piezoelectric crystal (lithium niobate) substrate, along the sidewalls of microchannels (50 μm or 280 μm wide and 200 μm deep) fabricated in the substrate, can give rise to throughflow with velocities of the order 10 mm/s. This streaming flow in the direction along which the sur...