High-power CW single-frequency Nd:YVO4/LBO laser quasi-continuously tuneable over a wide frequency range

2014 ◽  
Author(s):  
Daba Radnatarov ◽  
Sergey Khripunov ◽  
Sergey Kobtsev ◽  
V. Lunin
Keyword(s):  
High Power ◽  
Wide Frequency Range ◽  
Single Frequency ◽  
Frequency Range

scholarly journals Center Impedance Method for Estimating Complex Modulus with Wide Frequency Range and Large Loss Factors

2021 ◽  
Vol 2021 ◽  
pp. 1-23
Author(s):  
Ryuzo Horiguchi ◽  
Yoshiro Oda ◽  
Keito Sato ◽  
Hiroto Kozuka ◽  
Takao Yamaguchi
Keyword(s):  
Loss Factor ◽  
Wide Frequency Range ◽  
Frequency Function ◽  
Single Frequency ◽  
Impedance Method ◽  
Frequency Range ◽  
Simple Method ◽  
Large Loss ◽  
Mobility Data ◽  
Loss Factors

A simple method for determining viscoelasticity over a wide frequency range using the frequency response function (FRF) mobility obtained by the center impedance method is presented. As user data comprise the FRF between the velocity of the excitation rod and excitation force, it is challenging to separate the signal and noise. Our proposed method is based on the FRF obtained from the analytical solution of the equation of motion of the viscoelastic beam and relationship between the complex wavenumber (real wavenumber and attenuation constant) of flexural wave and viscoelasticity. Furthermore, a large loss factor can be handled over a wide frequency range without using the half-power bandwidth. In this study, actual FRF mobility data containing noise were processed using preprocessing, inverse calculation, and postprocessing. Preprocessing removed low-coherence data, compensates for the effects of instrument gain, and transformed the FRF into its dimensionless equivalent. Then, inverse calculations were used to solve the mobility equation and determine the complex wavenumber. In postprocessing, the complex wavenumber obtained by the inverse calculation was curve fitted using functions with mechanical significance. Consequently, the storage modulus based on the curve-fitted complex wavenumber was a monotonically increasing frequency function. The loss factor had a smooth frequency dependence such that it has the maximum value at a single frequency. The proposed method can be applied to composite materials, where the application of time-temperature superposition is challenging. We utilized the measured FRF mobility data obtained over a duration of several seconds, and this method can also be applied to materials with large loss factors of 1 or more.

High-power pulsed CO2laser continuously tunable over a wide frequency range

1978 ◽  
Vol 8 (7) ◽  
pp. 870-872 ◽  
Author(s):  
Yu I Bychkov ◽  
Gennadii A Mesyats ◽  
V M Orlovskiĭ ◽  
V V Osipov ◽  
V V Savin
Keyword(s):  
High Power ◽  
Wide Frequency Range ◽  
Frequency Range

scholarly journals Active Absorption of Perforated Plate Based on Airflow

2005 ◽  
Vol 24 (3) ◽  
pp. 171-180 ◽  
Author(s):  
Zhu Congyun ◽  
Huang Qibai ◽  
Zhao Ming ◽  
Wang Yong
Keyword(s):  
Numerical Calculation ◽  
Absorption Coefficient ◽  
Sound Wave ◽  
Perforated Plate ◽  
Rigid Wall ◽  
Wide Frequency Range ◽  
Single Frequency ◽  
Frequency Range ◽  
Low Frequencies ◽  
Active Absorption

The theory of active absorption of a perforated plate is considered in this paper. The perforated plate is the material of active absorption and the frequency of the incident sound wave is measured. According to this frequency the depth of the cavity between the perforated plate and the rigid wall, is moved in order that resonance occurs so that the absorption coefficient is maximal. According to the numerical calculation, when the perforated plate is resonant, the distance moved is large at low frequencies and the absorption coefficient is low in some conditions. It is effective for a single frequency of incident sound wave, yet it is difficult for a wide frequency range. Hence active absorption based on airflow is considered and calculations and experiments an carried out. The results denote that this method of active absorption is practical.

Installation for testing electronic voltmeters over a wide frequency range

1976 ◽  
Vol 19 (10) ◽  
pp. 1525-1526
Author(s):  
A. M. Fedorov ◽  
V. V. Krestovskii ◽  
V. S. Kiselev ◽  
S. A. Razumovskii ◽  
V. A. Shcheglov
Keyword(s):  
Wide Frequency Range ◽  
Frequency Range
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