On the practical use of a three-microphone technique for in-situ acoustic impedance measurements on double layer flow duct liners

1981 ◽  
Author(s):  
T. ZANDBERGEN
Keyword(s):  
Double Layer ◽  
Acoustic Impedance ◽  
Impedance Measurements ◽  
Layer Flow ◽  
Flow Duct

On the “In-Situ” Control of Acoustic Liner Attenuation

1977 ◽  
Vol 99 (1) ◽  
pp. 63-70 ◽  
Author(s):  
P. D. Dean
Keyword(s):  
Acoustic Impedance ◽  
Test Facility ◽  
Small Scale ◽  
In Situ Control ◽  
Acoustic Liner ◽  
Flow Duct

In this paper a concept is presented which enables the attenuation of sound in a lined duct to be controlled via the control of the fundamental liner characteristic (the acoustic impedance). The concept is described and modeled by a semiempirical analysis. The feasibility is demonstrated by means of measurements of attenuation and local impedance in a small scale flow duct test facility.

Cyclic Voltammetry, Impedance Measurements and In-Situ EPR Studies of Conjugated Polymers

1991 ◽  
Vol 21 ◽  
pp. 139-162 ◽  
Author(s):  
L. Wuckel ◽  
M. Schwarzenberg ◽  
A. Bartl ◽  
H.G. Döge
Keyword(s):  
Cyclic Voltammetry ◽  
Conjugated Polymers ◽  
Impedance Measurements

Measuring the Sea: Marsili’s Oceanographic Cruise (1679–80) and the Roots of Oceanography

2018 ◽  
Vol 48 (4) ◽  
pp. 845-860 ◽  
Author(s):  
Nadia Pinardi ◽  
Emin Özsoy ◽  
Mohammed Abdul Latif ◽  
Franca Moroni ◽  
Alessandro Grandi ◽  
...  
Keyword(s):  
Adriatic Sea ◽  
Aegean Sea ◽  
Experimental Methodology ◽  
Marmara Sea ◽  
Numerical Studies ◽  
Measurement Methodology ◽  
Geographical Position ◽  
Layer Flow ◽  
Current Inversion

ABSTRACTThe first in situ measurements of seawater density that referred to a geographical position at sea and time of the year were carried out by Count Luigi Ferdinando Marsili between 1679 and 1680 in the Adriatic Sea, Aegean Sea, Marmara Sea, and the Bosporus. Not only was this the first investigation with documented oceanographic measurements carried out at stations, but the measurements were described in such an accurate way that the authors were able to reconstruct the observations in modern units. These first measurements concern the “specific gravity” of seawaters (i.e., the ratio between fluid densities). The data reported in the historical oceanographic treatise Osservazioni intorno al Bosforo Tracio (Marsili) allowed the reconstruction of the seawater density at different geographic locations between 1679 and 1680. Marsili’s experimental methodology included the collection of surface and deep water samples, the analysis of the samples with a hydrostatic ampoule, and the use of a reference water to standardize the measurements. A comparison of reconstructed densities with present-day values shows an agreement within 10%–20% uncertainty, owing to various aspects of the measurement methodology that are difficult to reconstruct from the documentary evidence. Marsili also measured the current speed and the depth of the current inversion in the Bosporus, which are consistent with the present-day knowledge. The experimental data collected in the Bosporus enabled Marsili to enunciate a theory on the cause of the two-layer flow at the strait, demonstrated by his laboratory experiment and later confirmed by many analytical and numerical studies.

Sign in / Sign up

Export Citation Format

Share Document