Multiple reflected beam synthesis of fields excited by a high‐frequency oblique beam input in an elastic plate

1992 ◽  
Vol 91 (4) ◽  
pp. 2016-2024 ◽  
Author(s):  
Smaine Zeroug ◽  
Leopold B. Felsen
Keyword(s):  
Elastic Plate ◽  
High Frequency

scholarly journals Hinge-type FBG acceleration sensor based on double elastic plate

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zhongchao Qiu ◽  
Jinquan Zhang ◽  
Yuntian Teng ◽  
Zhitao Gao ◽  
Li Hong
Keyword(s):  
Resonance Frequency ◽  
Elastic Plate ◽  
High Frequency ◽  
Large Scale ◽  
Acceleration Sensor ◽  
Medium Frequency ◽  
Vibration Signals ◽  
High Frequency Vibration ◽  
Large Scale Structures ◽  
Scale Structures

AbstractIt is critical for the health monitoring of large-scale structures such as bridge, railway and tunnel to acquire the medium-frequency and high-frequency vibration signals. To solve the problems of low sensitivity and poor transverse anti-interference of the medium-frequency and high-frequency fiber acceleration sensor, a hinge-type Fiber Bragg Grating(FBG) acceleration sensor based on double elastic plate has been proposed, and the hinge and elastic plate are used as elastomer to realize the miniaturization and transverse interference suppression of the sensor. The MATLAB and the ANSYS are used for theoretical analysis and optimization of sensor sensitivity and resonance frequency, structural static stress analysis and modal simulation analysis, while the test system is built to test the sensor performance. The results show that the resonance frequency of the sensor is 1300 Hz; the sensor has a flat sensitivity response in the middle-high frequency band of 200–800 Hz; the sensitivity is about 20 pm/g, and the fiber central wavelength drift and acceleration have good linearity and stability, while the transverse anti-interference is about 3.16%, which provides a new idea for monitoring of medium-frequency and high-frequency vibration signals in large-scale structures.

scholarly journals Hinge-Type FBG Acceleration Sensor Based on Double Elastic Plate

2021 ◽  
Author(s):  
Zhongchao Qiu ◽  
Jinquan Zhang ◽  
Yuntian Teng ◽  
Zhitao Gao ◽  
Hong Li
Keyword(s):  
Resonance Frequency ◽  
Elastic Plate ◽  
High Frequency ◽  
Large Scale ◽  
Acceleration Sensor ◽  
Medium Frequency ◽  
Vibration Signals ◽  
High Frequency Vibration ◽  
Large Scale Structures ◽  
Scale Structures

Abstract It is critical for the health monitoring of large-scale structures such as bridge, railway and tunnel to acquire the medium-frequency and high-frequency vibration signals. To solve the problems of low sensitivity and poor transverse anti-interference of the medium-frequency and high-frequency fiber acceleration sensor, a hinge-type Fiber Bragg Grating(FBG) acceleration sensor based on double elastic plate has been proposed, and the hinge and elastic plate are used as elastomer to realize the miniaturization and transverse interference suppression of the sensor. The MATLAB and the ANSYS are used for theoretical analysis and optimization of sensor sensitivity and resonance frequency, structural static stress analysis and modal simulation analysis, while the test system is built to test the sensor performance. The results show that the resonance frequency of the sensor is 1300 Hz; the sensor has a flat sensitivity response in the middle-high frequency band of 200-800 Hz; the sensitivity is about 20 pm/g, and the fiber central wavelength drift and acceleration have good linearity and stability, while the transverse anti-interference is about 3.16%, which provides a new idea for monitoring of medium-frequency and high-frequency vibration signals in large-scale structures.

Wave Propagation in an Elastic Beam or Plate on an Elastic Foundation

1962 ◽  
Vol 29 (3) ◽  
pp. 459-464 ◽  
Author(s):  
J. R. Lloyd ◽  
Julius Miklowitz
Keyword(s):  
Wave Propagation ◽  
Elastic Foundation ◽  
Elastic Plate ◽  
High Frequency ◽  
Wave Train ◽  
Elastic Beam ◽  
Frequency Spectra ◽  
Short Waves ◽  
Exact Theory ◽  
Good Agreement

Presented is an analysis of wave propagation in an infinite elastic plate or beam on an elastic foundation, based on a comparison of frequency spectra (or wave-train solutions) from the exact equations and existing approximate bending theories. A distinct similarity is found between the spectrum representing the more exact theory of bending and the Rayleigh-Lamb spectrum for symmetric waves in a free elastic plate, including the existence of complex branches. Good agreement between the approximate theories and the exact equations is found for soft foundations under the usual restrictions on high-frequency, short waves.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

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