Capacitive frequency meter

1979 ◽  
Vol 22 (6) ◽  
pp. 738-739
Author(s):  
B. A. Kaznacheev
1963 ◽  
Vol 6 (5) ◽  
pp. 417-421
Author(s):  
V. I. Safonov ◽  
I. N. Ivanov ◽  
V. N. Komissarova

1969 ◽  
Vol 12 (1) ◽  
pp. 81-84
Author(s):  
K. I. Didenko ◽  
V. N. Laskavyi

1978 ◽  
Vol 14 (12) ◽  
pp. 366 ◽  
Author(s):  
M.J. Underhill ◽  
M. Sarhadi ◽  
C.S. Aitchison

2007 ◽  
Vol 50 (2) ◽  
pp. 215-220 ◽  
Author(s):  
A. M. Goncharenko ◽  
V. A. Zhmud’ ◽  
A. A. Voevoda ◽  
S. A. Avilov
Keyword(s):  

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Dongjun Chen ◽  
Benniu Zhang ◽  
Xingxing Li ◽  
Chong Tu ◽  
Can Yuan ◽  
...  

The prestress loss is one of the main factors affecting the safety of prestressed concrete structure. While the detecting signals like sound and light are difficult to spread in steel strands, there is no effective method for prestress detection of the bonded prestressed steel strands in existing structures yet. In this paper, taking into consideration that the electromagnetic oscillation characteristic can make the signal propagate effectively on the bonded prestressed steel strands, a nondestructive prestress detection method based on the electromagnetic effect to detect oscillation frequency is proposed. In a detection circuit, the steel strands are simulated as an inductance component, in which an induced electromagnetic signal passes through the steel strands to form resonance. And then, a frequency meter is used to detect the oscillation frequency of the resonant circuit. The oscillation frequency is supposed to have relationship with the prestress loading on the steel strands. A section of steel strands with a length of 1.2 m is adopted to test the correlation of stress and oscillation frequency. Both the theoretical and experimental results show that the resonant frequency of the circuit decreases with the increase of the stress of the strand and is linear in a certain range.


1973 ◽  
Vol 16 (5) ◽  
pp. 732-734
Author(s):  
V. T. Nikolaev ◽  
V. N. Chernyaev
Keyword(s):  

Geophysics ◽  
1965 ◽  
Vol 30 (5) ◽  
pp. 883-890 ◽  
Author(s):  
Raoul I. Giret

This magnetometer has been developed by C.S.F. (Compagnie Générale de Télégraphie Sans Fil) and C.G.G. (Compagnie Générale de Géophysique). The magnetic field is measured by an optical pumping sensor giving a frequency proportional to the field. A digital frequency‐meter delivers a reading each second with a sensitivity of ± one period (31.5 periods for one gamma). These readings are recorded on a magnetic tape recorder and on an analog TEXAS recorder. The digital data are processed on a 1620 IBM. During the flight a second magnetometer records the variation of the earth’s field in a ground station located in the center of the area surveyed. The ground record data are subtracted from the airborne data. The following data obtained with this equipment are presented: Analog record with a sensitivity of one gamma for two mm. Restitution with 1620 IBM and CALCOMP of the magnetic record to an analog record with a sensitivity of one gamma for one cm. Isogam maps with a contour interval of one gamma and some intermediate contours at 0.5 gamma.


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