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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

A method to separate wind-tunnel background noise and wind noise from interior measurements

Stoker, Robert W. 05 1900 (has links)
No description available.
12

Effects of vegetative barriers on highway traffic-generated noise

Harris, Roswell Alfred 12 1900 (has links)
No description available.
13

Car Roof Rack Cavity Noise

Harper, John January 2006 (has links)
The goal of the thesis was to change reduce the noise produced from a small cavity with grazing sub sonic flow, via alterations in geometry. Research was done into how noise was produced in cavities and existing research in the field. While most work had been done in super sonic flow, little had been done for small cavities at slow, automobile level speeds. Despite the small amount of work done, several features of geometry were noted as affecting the production of sound in cavities. Several of these were chosen to be tested. A modular test rig was designed to allow easy change between the various geometries being tested. It had a flat top surface (of which the cavity came off) to keep the experiment generic, while the bottom surface was a combination of two slopes to keep disturbance to the flow at a minimum and reduce the background noise. A new working section, contraction and anechoic termination were designed and produced to add onto the existing wind tunnel in the mechanical engineering wing at the University of Canterbury. The noise production from a cavity is dependent upon the interaction between the vortices travelling in a 'shear layer' over the cavity throat interact with the front and rear edge of the cavity throat. By minimising the impact to the vortices as they travel between cavity edges, significant noise attenuation can occur. The most successful strategies were lowering the rear edge relative to the front edge and putting ramps on the front and rear edges. To test the principle of superposition, these two strategies, along with an 'L' plate (the third best strategy) were put together to make a 'Super' cavity. the noise spectrum from this cavity was almost identical to the background noise. Removal of the 'L' plate improved sound attenuation even more. Work to do in the future includes testing more examples of each geometry modification, as time constraints minimised the variations on each modification tested. Additionally, the super cavity should be tested in a curved, aerofoil/roof rack extrusion, to see if it as effective in a curved environment as a flat one. All experimental work was done at 100km/h, to coincide with the open road speed limit in New Zealand. The tests should be redone at different speeds, so a more complete picture of the cavity noise can be produced.
14

Spectral attenuation and wearability of circumaural hearing protectors as influenced by design attributes and work-related activity /

Grenell, James F., January 1988 (has links)
Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1988. / Vita. Abstract. Includes bibliographical references (leaves 211-218). Also available via the Internet.
15

Effect of opening size on the effectiveness of a noise enclosure on the side facing the opening

Hegde, Amit Damodar. January 1900 (has links)
Thesis (M.S.)--West Virginia University, 2005 / Title from document title page. Document formatted into pages; contains x, 59 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 55-56).
16

A study on the applicability of overseas road traffic noise prediction models to Hong Kong /

Lui, Wai-keung. January 1999 (has links)
Thesis (M. Sc.)--University of Hong Kong, 1999. / Includes bibliographical references.
17

A new methodology for sizing and performance predictions of a rotary wing ejector

Moodie, Alex Montfort. January 2008 (has links)
Thesis (Ph.D)--Aerospace Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Dr. Daniel P. Schrage; Committee Member: Dr. Lakshmi N. Sankar; Committee Member: Dr. Richard J. Gaeta; Committee Member: Dr. Stephen M. Ruffin; Committee Member: Mark H. Waters. Part of the SMARTech Electronic Thesis and Dissertation Collection.
18

A comparative study of the physical mechanisms related to highway noise barrier insertion loss measurements versus modeling assumptions /

Shu, Ning, January 2005 (has links) (PDF)
Thesis (Ph. D.)--University of Louisville, 2005. / Department of Civil and Environmental Engineering. Vita. "May 2005." Includes bibliographical references (leaves 183-190).
19

Acoustic propagation in nonuniform circular ducts carrying near sonic mean flows /

Kelly, Jeffrey J. January 1981 (has links)
Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1981. / Vita. Abstract. Includes bibliographical references (leaves 64-69). Also available via the Internet.
20

A comparative study of the physical mechanisms related to highway noise barrier insertion loss measurements versus modeling assumptions /

Shu, Ning, January 2005 (has links) (PDF)
Thesis (Ph. D.)--University of Louisville, 2005. / Department of Civil and Environmental Engineering. Vita. Includes bibliographical references (leaves 183-190). Also available online via the University of Louisville website (http://etd.louisville.edu/).

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