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  • 1
    Electronic Resource
    Electronic Resource
    THE VISCOSITY OF CELLULOSE IN PHOSPHORIC ACID SOLUTIONS1 (1938)
    s.l. : American Chemical Society
    The @journal of physical chemistry 〈Washington, DC〉 42 (1938), S. 921-933 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/j100902a004
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    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    Pretreatment of Wood with Hot Dilute Acid (1937)
    s.l. : American Chemical Society
    Industrial and engineering chemistry 9 (1937), S. 234-235 
    Details
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ac50109a018
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    Paper (German National Licenses)
    Fulltext
  • 3
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    Measurements of propeller noise in a light turboprop airplane (1989)
    In:  Other Sources
    Details
    Publication Date: 2011-08-19
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: Journal of Aircraft (ISSN 0021-8669); 26; 40-47
    Format: text
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    NASA TECHNICAL REPORTS
  • 4
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    Propeller aircraft interior noise model: User's manual for computer program (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A computer program entitled PAIN (Propeller Aircraft Interior Noise) has been developed to permit calculation of the sound levels in the cabin of a propeller-driven airplane. The fuselage is modeled as a cylinder with a structurally integral floor, the cabin sidewall and floor being stiffened by ring frames, stringers and floor beams of arbitrary configurations. The cabin interior is covered with acoustic treatment and trim. The propeller noise consists of a series of tones at harmonics of the blade passage frequency. Input data required by the program include the mechanical and acoustical properties of the fuselage structure and sidewall trim. Also, the precise propeller noise signature must be defined on a grid that lies in the fuselage skin. The propeller data are generated with a propeller noise prediction program such as the NASA Langley ANOPP program. The program PAIN permits the calculation of the space-average interior sound levels for the first ten harmonics of a propeller rotating alongside the fuselage. User instructions for PAIN are given in the report. Development of the analytical model is presented in NASA CR 3813.
    Keywords: ACOUSTICS
    Type: NASA-CR-172425 , NAS 1.26:172425 , REPT-5058
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 5
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    In-flight acoustic measurements on a light twin-engined turboprop airplane (1985)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: Four series of flight tests were conducted to measure sound pressure levels inside and outside the cabin of a twin-engined turboprop airplane. Particular emphasis was placed on harmonics of the propeller blade passage frequency. The cabin was unfurnished for the first three flights, when the main objective was to investigate the repeatability of the data. For the fourth flight, the cabin was treated with fiberglass batts. Typically, the exterior sound pressure levels were found to vary 3 to 5 dB for a given harmonic, but variations as high as 8 dB were observed. The variability of harmonic levels within the cabin was slightly higher but depended on control of the relative phase between the propellers; when phase was not controlled the average variability was about 10 dB. Noise reductions provided by the fuselage structure were in the range of 20 to 40 dB, when an exterior microphone in the plane of rotation of the propeller was used as reference.
    Keywords: ACOUSTICS
    Type: NASA-CR-178004 , NAS 1.26:178004
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 6
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    Measurements of propeller noise in a light turboprop airplane (1987)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: In-flight acoustic measurements have been made on the exterior and interior of a twin-engined turboprop airplane under controlled conditions to study data repeatability. It is found that the variability of the harmonic sound pressure levels in the cabin is greater than that for the exterior sound pressure levels, typical values for the standard deviation being +2.0 dB and -4.2 dB for the interior, versus +1.4 dB and -2.3 dB for the exterior. When insertion losses are determined for acoustic treatments in the cabin, the standard deviations of the data are typically + or - 6.5 dB. It is concluded that additional factors, such as accurate and repeatable selection of relative phase between propellers, controlled cabin-air-temperatures, installation of baseline acoustic absorption, and measurement of aircraft attitude, should be considered in order to reduce uncertainty in the measured data.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: AIAA PAPER 87-2737
    Format: text
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    NASA TECHNICAL REPORTS
  • 7
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    Propeller aircraft interior noise model (1984)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: An analytical model was developed to predict the interior noise of propeller-driven aircraft. The fuselage model is that of a cylinder with a structurally-integral floor. The cabin sidewall is stiffened by stringers and ring frames, and the floor by longitudinal beams. The cabin interior is covered with a sidewall treatments consisting of layers of porous material and an impervious trim septum. Representation of the propeller pressure field is utilized as input data in the form of the propeller noise signature at a series of locations on a grid over the fuselage structure. Results obtained from the analytical model are compared with test data measured by NASA in a scale model cylindrical fuselage excited by a model propeller.
    Keywords: ACOUSTICS
    Type: NASA-CR-3813 , NAS 1.26:3813 , BBN-5058
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 8
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    Analytical prediction of the interior noise for cylindrical models of aircraft fuselages for prescribed exterior noise fields. Phase 1: Development and validation of preliminary analytical models (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The basic theoretical work required to understand sound transmission into an enclosed space (that is, one closed by the transmitting structure) is developed for random pressure fields and for harmonic (tonal) excitation. The analysis is used to predict the noise reducton of unpressurized unstiffened cylinder, and also the interior response of the cylinder given a tonal (plane wave) excitation. Predictions and measurements are compared and the transmission is analyzed. In addition, results for tonal (harmonic) mechanical excitation are considered.
    Keywords: ACOUSTICS
    Type: NASA-CR-159363 , BBN-4420
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 9
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    Evaluation of Aero Commander sidewall vibration and interior acoustic data: Static operations (1980)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Results for the vibration measured at five locations on the fuselage structure during static operations are presented. The analysis was concerned with the magnitude of the vibration and the relative phase between different locations, the frequency response (inertance) functions between the exterior pressure field and the vibration, and the coherent output power functions at interior microphone locations based on sidewall vibration. Fuselage skin panels near the plane of rotation of the propeller accept propeller noise excitation more efficiently than they do exhaust noise.
    Keywords: AIRCRAFT DESIGN, TESTING AND PERFORMANCE
    Type: NASA-CR-159290 , BBN-4016
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 10
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    Interior noise control prediction study for high-speed propeller-driven aircraft (1979)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: An analytical model was developed to predict the noise levels inside propeller-driven aircraft during cruise at M = 0.8. The model was applied to three study aircraft with fuselages of different size (wide body, narrow body and small diameter) in order to determine the noise reductions required to achieve the goal of an A-weighted sound level which does not exceed 80 dB. The model was then used to determine noise control methods which could achieve the required noise reductions. Two classes of noise control treatments were investigated: add-on treatments which can be added to existing structures, and advanced concepts which would require changes to the fuselage primary structure. Only one treatment, a double wall with limp panel, provided the required noise reductions. Weight penalties associated with the treatment were estimated for the three study aircraft.
    Keywords: ACOUSTICS
    Type: NASA-CR-159200 , BBN-4026
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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