Renormalized resonance frequencies of a ferrite sphere coupled to an LR circuit: Comparison of theory and experiment

2005 ◽  
Vol 24B (1) ◽  
pp. 39-45
Author(s):  
L.Q. English ◽  
C. Kerestes ◽  
G. Rydzag
Author(s):  
Pezhman A. Hassanpour ◽  
Ebrahim Esmailzadeh ◽  
William L. Cleghorn ◽  
James K. Mills

Among many different mechanisms that are used for excitation and detection of vibration of micro-beam resonators, electrostatic comb-drives have the benefit of simplicity and large range of linear operation. The disadvantage of using comb-drives is the effect of added mass to the beam; however, the analytical model of the beam-mass system predicts that this shortcoming can be overcome by proper adjustment of the mass, rotary inertia, and location of the comb-drive. In addition, the analytical model can predict the effect of the axial force of the beam on the resonance frequencies. In this paper, the results of the experiments on two resonators are presented. These results are used to verify the validity of the analytical model and finding its parameters. Very close agreement between the theory and experiment is observed. The residual stress of the MEMS structural layer is measured using the calibrated analytical model parameters.


Author(s):  
Gertrude F. Rempfer

I became involved in electron optics in early 1945, when my husband Robert and I were hired by the Farrand Optical Company. My husband had a mathematics Ph.D.; my degree was in physics. My main responsibilities were connected with the development of an electrostatic electron microscope. Fortunately, my thesis research on thermionic and field emission, in the late 1930s under the direction of Professor Joseph E. Henderson at the University of Washington, provided a foundation for dealing with electron beams, high vacuum, and high voltage.At the Farrand Company my co-workers and I used an electron-optical bench to carry out an extensive series of tests on three-electrode electrostatic lenses, as a function of geometrical and voltage parameters. Our studies enabled us to select optimum designs for the lenses in the electron microscope. We early on discovered that, in general, electron lenses are not “thin” lenses, and that aberrations of focal point and aberrations of focal length are not the same. I found electron optics to be an intriguing blend of theory and experiment. A laboratory version of the electron microscope was built and tested, and a report was given at the December 1947 EMSA meeting. The micrograph in fig. 1 is one of several which were presented at the meeting. This micrograph also appeared on the cover of the January 1949 issue of Journal of Applied Physics. These were exciting times in electron microscopy; it seemed that almost everything that happened was new. Our opportunities to publish were limited to patents because Mr. Farrand envisaged a commercial instrument. Regrettably, a commercial version of our laboratory microscope was not produced.


1978 ◽  
Vol 39 (12) ◽  
pp. 1355-1363 ◽  
Author(s):  
L.G. Caron ◽  
M. Miljak ◽  
D. Jerome

1986 ◽  
Vol 150 (10) ◽  
pp. 321
Author(s):  
V.L. Dunin-Barkovskii

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