The sonic analogue of a gravitational black hole in dilute-gas Bose-Einstein condensates is investigated. It is shown that there exist both dynamically stable and unstable configurations which, in the hydrodynamic limit, exhibit a behavior completely analogous to that of gravitational black holes. The dynamical instabilities involve creation of quasiparticle pairs in positive and negative energ...

We follow the approach used by Davies and Pringle (1981) and discuss the trans-sonic substage of the propeller regime. This substage is intermediate between the supersonic and subsonic propeller substages. In the trans-sonic regime an envelope around a magnetosphere of a neutron star passes through a kind of a reorganization process. The envelope in this regime consists of two parts. In the bot...

Investigation of general-relativistic spherically symmetric steady accretion of self-gravitating perfect fluid onto compact objects reveals the existence of two weakly accreting regimes. In the first (corresponding to the test fluid approximation) the mass of the central object is much larger than the mass of the accreting fluid; in the second the mass of the fluid dominates. The stability of t...

We have developed an experiment to study the propagation of laboratory synthesized fatigue cracks under various controlled conditions during Sonic IR inspection. The experiment provides for good repeatability in testing. The parameters of interest include the initial crack length, load history (stress intensity and load ratio) during crack generation, geometry of the crack, material and also th...

Development of a next generation airplane, which cruises near sonic speed, received considerable attention in 2002. To investigate aerodynamic characteristics and validity of CFD codes as a design tool in this new cruise condition, detailed wind tunnel test and CFD validation study was conducted in near sonic regime about the NEXST-1, unpowered supersonic experimental vehicle as a cooperative r...

The development of a passive, sonic crystal-based device with unusual properties will be reported. This device combines a 1D sonic crystal, a nonlinear medium, and an acoustic low pass filter to allow broadband ultrasound propagation as a collimated beam for specialized underwater communication. The signal to be transmitted is first amplitude modulated with a high-frequency ultrasonic carrier w...

Three types of sonic cannons: Sonic cannons have had three incarnations over the years. The first implementation uses very low frequency sounds (essentially in the octave below the lower note on a piano keyboard) that have a significant vibro-tactile, or " whole body " response. This has been well studied in the literature and can result in nausea, a feeling of fullness in the chest and even he...

This paper discusses an approach to instrument conception that is based on a careful consideration of the coupling of tactile and sonic gestural action across the layers of physical and computational material in coordinated dynamical variation. To this end we propose a design approach that not only considers the materiality of the instrument, but leverages it as a central part of the conception...

INTRODUCTION The present investigation evaluated the ability of a new passive sonic irrigation (sonic group) system (EndoActivator) to eliminate cultivable bacteria from root canals in vivo and compared it with that of standard syringe irrigation (control group). METHODS Data were obtained by using bacteriologic sampling of root canals treated by endodontic residents. Sampling results from 1 ...

Advancements in embedded computer platforms have allowed data to be collected and shared between objects—or smart devices—in a network. While this has resulted in highly functional outcomes in fields such as automation and monitoring, there are also implications for artistic and expressive systems. In this paper we present a pluralistic approach to incorporating environmental factors within the...