1,266 Matching Results

Search Results

Advanced search parameters have been applied.

Aircraft Hushkits: Noise and International Trade

Description: This report discusses aircraft noise regulations as they relate to hushkits, which is a combination of strategies designed to reduce aircraft noise. These strategies can include new technologies, redesigned engine enclosures, replacement engine components, entirely new engines, or a combination of any of the above. This report dicusses the new EU regulation limiting hushkitted commercial jet aircraft in the EU, the United States' response to this regulation, and the effect this could have on international air travel relations.
Date: May 8, 2000
Creator: Fischer, John W
Partner: UNT Libraries Government Documents Department

Increasing the Dynamic Range of Audio THD Measurements Using a Novel Noise and Distortion Canceling Methodology

Description: The objective of this study was to determine how a new experimental methodology for measuring Total-Harmonic-Distortion (THD) of operational amplifiers functioned when compared with two standard methodologies, and whether the new methodology offers any improvement in noise floor and dynamic range along with distortion canceling of the sine-wave source used in the testing. The new methodology (THD) is being tested against two standard methodologies: Spectral Analysis using a tuned receiver type Spectrum Analyzer with Notch Filter pre-processing, and a digitized Fast Fourier Transform (FFT) using Notch Filter pre-processing. The THD results appear to agree across all methodologies, and across all items of the sample within all methodologies, to within a percent or less. The distortion and noise canceling feature of the new methodology appeared to function as expected and in accordance with theory. The sample tested in the study consisted of thirty-five NE5534 operational amplifiers produced by Texas Instruments, Inc. and purchased from a local store. The NE5534 is a low-noise, low-distortion, operational amplifier that is widely used in industry and is representative of today's best audio amplifiers.
Access: This item is restricted to UNT Community Members. Login required if off-campus.
Date: May 2003
Creator: Dunipace, Richard Alan
Partner: UNT Libraries

The Effect of Noise on Pulse Height Resolution

Description: Report wherein "[a] statistical study of base line fluctuations is used to relate noise measurements with the resolution spread of a pulse height analysis system. The resolution is inversely proportional to the signal-to-noise ratio. The proportionality constant is derived on the basis of a normal amplitude distribution for noise. A review of noise measuring techniques is given and adapted for use with electronic voltmeters. The form factors required to interpret meter readings in terms of the RMS value of noise are described" (p. 1).
Date: January 1962
Creator: Meth, Irving M. & Graveson, Robert T.
Partner: UNT Libraries Government Documents Department

Characterizing Noise and Harmonicity: The Structural Function of Contrasting Sonic Components in Electronic Composition

Description: This dissertation examines the role of noise in shaping the form of several recent musical compositions. This study demonstrates how the contrast of noisy sounds and harmonic sounds can impact the structure of compositions. Depending on context, however, the specific use and function of noise can vary substantially from one work to the next. The first portion of this paper describes methods for quantifying noise content using FFT analysis procedures. A number of tests on instrumental and synthetic sound sources are described in order to demonstrate how the analysis system may react to certain sounds. The second part of this document consists of several analyses of whole musical works. Works for acoustic instruments are examined first, followed by works for electronic media. During these analyses, it becomes clear that while the use of noise in each work is based largely upon context, some common patterns do exist across different works. The final portion of the paper examines an original work which was written with the function of noise specifically in mind. The original work is put through the same analysis procedures as works seen earlier in the paper, and some conclusions are drawn regarding both the possibilities and limitations of noise analysis as a compositional tool.
Date: May 2010
Creator: Dribus, John Alexander
Partner: UNT Libraries

Spontaneous Brain Activity as a Source of Ideal 1/f Noise

Description: In this article, the authors study the electroencephalogram (EEG) of 30 closed-eye subjects with a technique of analysis recently proposed to detect punctual events signaling rapid transitions between different metastable states.
Date: December 18, 2009
Creator: Allegrini, Paolo; Menicucci, Danilo; Bedini, Remo; Fronzoni, Leone; Gemignani, Angelo; Grigolini, Paolo et al.
Partner: UNT College of Arts and Sciences

A Flight Study of the Effects of Noise Filtering in the Attack Display on the Pilot's Tracking Performance

Description: Memorandum presenting flight tests conducted with a director-type radar fire-control system, with scope presentation of the steering information, to determine the effects of attack-display smoothing on the pilot's tracking and steering effectiveness in tail-chase and lead-collision beam attacks. Results regarding tail-chase attacks and lead-collision beam attacks are provided.
Date: September 10, 1958
Creator: Turner, Howard L. & Heinle, Donovan R.
Partner: UNT Libraries Government Documents Department

Vortex Noise From Rotating Cylindrical Rods

Description: "A series of round rods of the some diameter were rotated individually about the mid-point of each rod. Vortices are shed from the rods when in motion, giving rise to the emission of sound. With the rotating system placed in the open air, the distribution of sound in space, the acoustical power output, and the spectral distribution have been studied. The frequency of emission of vortices from any point on the rod is given by the formula of von Karman" (p. 1).
Date: February 1935
Creator: Stowell, E. Z. & Deming, A. F.
Partner: UNT Libraries Government Documents Department

Experiments in External Noise Reduction of Light Airplanes

Description: This note is part of a program with the objective of finding practical ways of reducing the external noise level of light airplanes in order to make them less objectionable to people on the ground. The current report covers noise measurements on standard light airplanes and on similar airplanes equipped with engine mufflers, propeller reduction gears, and propellers with various numbers of blades and blade shapes. The results indicate that reductions in noise level were found to result from muffling the engine and from reducing propeller tip speed and blade loading.
Date: May 1950
Creator: Beranek, Leo L.; Elwell, Fred S.; Roberts, John P. & Taylor, C. Fayette
Partner: UNT Libraries Government Documents Department

A survey of the aircraft-noise problem with special reference to its physical aspects

Description: Report presenting a background for various general phases of the aircraft-noise problem. The effects of noise are discussed and brief discussions of the physical characteristics of aircraft noise and some ways of protection from noise are included, as well as a bibliography of research related to the noise problem. At the time of this report, no easy and inexpensive solution to the aircraft-noise problem is currently available.
Date: May 1952
Creator: Hubbard, Harvey H.
Partner: UNT Libraries Government Documents Department

Sound-Level Measurements of a Light Airplane Modified to Reduce Noise Reaching the Ground

Description: "An army liaison-type airplane, representative of personal airplanes in the 150 to 200 horsepower class, has been modified to reduce propeller and engine noise according to known principles of airplane-noise reduction. Noise-level measurements demonstrate that, with reference to an observer on the ground, a noisy airplane of this class can be made quiet - perhaps more quiet than necessary. In order to avoid extreme and unnecessary modifications, acceptable noise levels must be determined" (p. 1).
Date: July 1948
Creator: Vogeley, A. W.
Partner: UNT Libraries Government Documents Department

Propeller Rotation Noise Due to Torque and Thrust

Description: "Sound pressure of the first four harmonics of rotation from a full-scale two-blade propeller were measured and are compared with values calculated from theory. The comparison is made (1) for the space distribution with constant tip speed and (2) for fixed space angles with variable tip speed. A relation for rotation noise from an element of radius developed by Gutin is given showing the effect of number of blades on the rotation noise" (p. 1).
Date: January 1940
Creator: Deming, Arthur F.
Partner: UNT Libraries Government Documents Department

Noise From Propellers With Symmetrical Sections at Zero Blade Angle, 2

Description: "In a previous paper (Technical Note No. 605), a theory was developed that required an empirical relation to calculate sound pressures for the higher harmonics. Further investigation indicated that the modified theory agrees with experiment and that the empirical relation was due to an interference phenomenon peculiar to the test arrangement used. Comparison is made between the test results for a two-blade arrangement and the theory" (p. 1).
Date: December 1938
Creator: Deming, A. F.
Partner: UNT Libraries Government Documents Department

Noise From Propellers With Symmetrical Sections at Zero Blade Angle

Description: "A theory has been deduced for the "rotation noise" from a propeller with blades of symmetrical section about the chord line and set at zero blade angle. Owing to the limitation of the theory, the equations give without appreciable error only the sound pressure for cases where the wave lengths are large compared with the blade lengths. With the aid of experimental data obtained from a two-blade arrangement, an empirical relation was introduced that permitted calculation of higher harmonics" (p. 1).
Date: July 1937
Creator: Deming, A. F.
Partner: UNT Libraries Government Documents Department