208,424 research outputs found
Acousto-elastic interaction in combustion chambers
This thesis deals with the interaction between combustion, acoustics and vibrations with emphasis on frequencies below 500 Hz. Extensive literature is available on the interaction between combustion and acoustics and much work is also available on the interaction between acoustics and vibration. The work presented in this thesis attempts to combine these fields in order to calculate the vibrations of the liner
Literary Acoustics
Bringing together sound studies and intermediality theory, this essay revisits the notion of âliterary acousticsâ to inquire into the usefulness of intermediality studies for analyzing the relations between literature and sound. The second part of the essay is dedicated to an illustrative analysis of Ben Marcusâs highly experimental, noisy book The Age of Wire and String
Sonar acoustics
The problem of producing a model to determine the beam pattern produced by a sonar set in the form of a circular cylinder with hemispherical end caps is studied. The beam width and the position of the beam centre are also considered and the results of the models are compared with experimental findings. Possible reasons for the discrepancies between these theoretical and experimental results are examined, providing insight into developing more sophisticated mathematical models. The beam patterns were produced using a combination of Matlab and Fortran 77 programs incorporating subroutines from the NAG library. Experimental results and data are included with the kind permission of Thomson Marconi Sonar Systems Ltd
The use of acoustics in space exploration
In recent years increased attention has been paid to the potential uses of acoustics forextraterrestrial exploration. The extent to which acoustics per se is used in these studiesvaries greatly. First, there are the cases in which acoustics is simply the medium throughwhich some other time-varying non-acoustic signal (such as the output of a cosmic raydetector) is communicated to humans. Second, perturbations in a non-acoustic signal (e.g.EM) are interpreted through mechanisms relating to acoustic perturbations in the sourcematerial itself. Third, some probes have made direct measurements of acoustic signalswhich have been generated by the probe itself, as is done for example to infer the localatmospheric sound speed from the time-of-flight of an acoustic pulses over a shortdistance (O(10 cm)). Fourth, some studies have discussed ways of interpreting thenatural acoustic signals generated by the extraterrestrial environment itself. The reportdiscusses these cases and the limitations, implications and opportunities forextraterrestrial exploration using acoustics
Propagation of sound through a sheared flow
Sound generated in a moving fluid must propagate through a shear layer in order to be measured by a fixed instrument. These propagation effects were evaluated for noise sources typically associated with single and co-flowing subsonic jets and for subcritical flow over airfoils in such jets. The techniques for describing acoustic propagation fall into two categories: geometric acoustics and wave acoustics. Geometric acoustics is most convenient and accurate for high frequency sound. In the frequency range of interest to the present study (greater than 150 Hz), the geometric acoustics approach was determined to be most useful and practical
Nonclassical acoustics
A statistical approach to sound propagation is considered in situations where, due to the presence of large gradients of properties of the medium, the classical (deterministic) treatment of wave motion is inadequate. Mathematical methods for wave motions not restricted to small wavelengths (analogous to known methods of quantum mechanics) are used to formulate a wave theory of sound in nonuniform flows. Nonlinear transport equations for field probabilities are derived for the limiting case of noninteracting sound waves and it is postulated that such transport equations, appropriately generalized, may be used to predict the statistical behavior of sound in arbitrary flows
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