Far-field characteristics of installed F404 engine noise

Matthew A. Christian; Logan T. Mathews; Kent L. Gee; Jon P. Johnson; Steven C. Campbell

doi:10.1121/10.0008152

Far-field characteristics of installed F404 engine noise

The Journal of the Acoustical Society of America ◽

10.1121/10.0008152 ◽

2021 ◽

Vol 150 (4) ◽

pp. A213-A213

Author(s):

Matthew A. Christian ◽

Logan T. Mathews ◽

Kent L. Gee ◽

Jon P. Johnson ◽

Steven C. Campbell

Keyword(s):

Far Field ◽

Engine Noise

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The Application of Singular Value Decomposition to Determine the Sources of Far Field Diesel Engine Noise

SAE International Journal of Engines ◽

10.4271/2013-01-1974 ◽

2013 ◽

Vol 6 (2) ◽

pp. 1386-1393 ◽

Cited By ~ 3

Author(s):

Michael D. Hayward ◽

J. Stuart Bolton ◽

Patricia Davies

Keyword(s):

Diesel Engine ◽

Singular Value Decomposition ◽

Singular Value ◽

Far Field ◽

Engine Noise ◽

Value Decomposition

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Possible applications of fraunhofer holography in high resolution electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100108258 ◽

1978 ◽

Vol 36 (1) ◽

pp. 222-223 ◽

Cited By ~ 1

Author(s):

N. Bonnet ◽

M. Troyon ◽

P. Gallion

Keyword(s):

Electron Microscopy ◽

High Resolution ◽

Transfer Function ◽

Radiation Damage ◽

High Resolution Electron Microscopy ◽

Far Field ◽

Field Region ◽

Crystalline Materials ◽

Resolution Electron ◽

The Ideal

Two main problems in high resolution electron microscopy are first, the existence of gaps in the transfer function, and then the difficulty to find complex amplitude of the diffracted wawe from registered intensity. The solution of this second problem is in most cases only intended by the realization of several micrographs in different conditions (defocusing distance, illuminating angle, complementary objective apertures…) which can lead to severe problems of contamination or radiation damage for certain specimens.Fraunhofer holography can in principle solve both problems stated above (1,2). The microscope objective is strongly defocused (far-field region) so that the two diffracted beams do not interfere. The ideal transfer function after reconstruction is then unity and the twin image do not overlap on the reconstructed one.We show some applications of the method and results of preliminary tests.Possible application to the study of cavitiesSmall voids (or gas-filled bubbles) created by irradiation in crystalline materials can be observed near the Scherzer focus, but it is then difficult to extract other informations than the approximated size.

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