College of Engineering (COE)

Permanent URI for this community

https://hdl.handle.net/10919/5539
Note: The Department of Biological Systems Engineering is listed within the College of Agriculture and Life Sciences (CALS).

Browse

Browsing College of Engineering (COE) by Content Type "Abstract"

Now showing 1 - 7 of 7
  • Thumbnail Image
    Computer-aided, interactive design routine for the prediction of sound levels in irregularly shaped factory spaces
    Blanding, James M.; Mitchell, Larry D.; Hurst, Charles J. (Acoustical Society of America, 1977)
    An interactive computer algorithm is presented which utilizes modified room acoustics theory to predict dBA sound pressure levels in regularly- and irregularly-shaped factory spaces. Irregularly positioned and nonuniform room absorptions are treated. The user-oriented algorithm, suited to remote interactive terminal operation, employs a conversational format to facilitate input of room dimensions, of absorption data, and of locations and noise levels of machinery. A redesign feature is included which employs three options. These allow the user to change sound source data and acoustic treatments in the process of finding the most economical accommodation of OSHA regulations during any phase of the factory design or redesign. [Work supported by NSF.]
  • Thumbnail Image
    Dissipative structure of shock waves in fluids having large specific heat
    Cramer, Mark S. (Acoustical Society of America, 1987)
    Recent studies indicate that the nonlinearity parameter 1 + B/2A may become negative in fluids whose specific heats are sufficiently large. The present study examines the dissipative structure of weak shocks in such fluids and contrasts the results obtained with those of the classical Taylor structure. Estimates for the thickness will also be presented. Conditions under which the thickness increases, rather than decreases, with increasing shock strength will be given.
  • Thumbnail Image
    Numerical-perturbation technique for the transverse vibrations of highly prestressed plates
    Nayfeh, Ali H.; Kamat, Manohar P. (Acoustical Society of America, 1975)
    Under the usual assumptions of small strains with moderately large rotations, the problem of the transverse vibrations of highly prestressed nonuniform annular plates is reduced to the solution of the differential equation governing the transverse vibration of the corresponding prestressed membrane subject to modified boundary conditions that account for the effects of bending. The method of composite expansions is used to determine these modified boundary conditions. The agreement of the present solution or results with known exact solutions for simple geometries demonstrates the efficiency of this method when compared with other well-known numerical techniques.
  • Thumbnail Image
    Prediction of sound pressure levels in irregularly shaped factory spaces
    Zinskie, John H.; Mitchell, Larry D.; Hurst, Charles J. (Acoustical Society of America, 1976)
    The prediction of sound pressure levels in irregularly shaped factory spaces is approached through an analysis of acoustically coupled rooms. Previous work has indicated that room surface sound absorption characteristics create a theoretical interdependence between the sound pressure fields in each coupled volume. Whenever a barrier is interposed between a sound source and observer, the effects of diffraction must also be considered. A computer algorithm was developed to predict sound pressure levels in irregularly shaped rooms using a modified statistical acoustic theory. The program is based on a conversational technique and requires the user to enter information regarding room geometry, surface absorptions, receiver placements, and source sound power and placement information. Several output options are provided, among which is a plan view print-plot of sound pressure level contours in the analysis room. [Work supported by NSF.]
  • Thumbnail Image
    Prediction of the sound diffracted around barriers in large rooms using an extension of Maekawa's approach
    Johnson, R. A.; Hurst, Charles J.; Mitchell, Larry D. (Acoustical Society of America, 1977)
    A computer program has been developed for the prediction of sound pressure levels in large, irregular rooms utilizing a geometric acoustics approach. Experiments indicated that the program gave good predictive accuracy when receiver positions were in the line of sight of the sound source. However, the accuracy was poor when the receiver was out of the line of sight. The present discussion reports on the further development of the program to include diffraction effects using an extension of Maekawa's approach for thin screens and right angle wedges. The program is capable of finding all valid diffracted rays which undergo three or fewer reflections before diffraction and three or fewer reflections after diffraction. Limited experimental work indicates good predictive accuracy.
  • Thumbnail Image
    Scattering of acoustic waves in a waveguide
    Sen, Rahul; Thompson, Charles (Acoustical Society of America, 1987)
    The problem of scattering from boundary discontinuity in a waveguide is discussed. The relationship between the static and dynamic representations of the scattered pressure field will be investigated for those frequencies falling below the first cross mode of the duct. Special attention is paid to the influence of cutoff cross modes to the solution of the pressure field. It is shown that the method of matched asymptotic expansions can be successfully used to determine globally valid pressure field junction conditions near a boundary discontinuity. The matching of exponentially decaying terms of the inner solution is shown to, in turn, contribute to the junction impedance and extend the frequency range of the solution's validity.
  • Thumbnail Image
    Sound transmission between absorbing parallel planes
    Hurst, Charles J.; Mitchell, Larry D. (Acoustical Society of America, 1976)
    Partially absorbing parallel surfaces can be dominant acoustical feature of many rooms. The sound fields in such rooms are not diffuse, which causes difficulty in predicting sound pressure levels. A method is developed for predicted sound pressure levels in these rooms. It rests on the prediction of sound pressure levels caused by a nondirectional source of known sound power radiating between absorbing parallel planes. The development proceeds from a geometrical acoustics viewpoint. Good correlation has been found between predicted and measured levels in existing rooms having simple geometries. [Work supported by NSF.]