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Message ID: 52     Entry time: Wed Jul 10 14:15:20 2013
Author: Emory Brown 
Type: Optics 
Category: General 
Subject: Comparison of Umax and the frequency of the lowest eigenmode against ratioR 

 I was able to run the looper program designed last week over the interval ratioR=[0.5, 0.9] with a step size of 0.01 and obtained the plot below with a minimal value of  Umax=1.4723e-10 J obtained for ratioR=0.71, which is about 3.2% less than the value of Umax=1.5202e-10 J when ratioR=1.  This is not very significant, but the shifting upward of the frequencies of the lowest eigenmodes as described in the previous post is.  Additionally, these curves both have their optimal points in the same region, with a ratioR value of about 0.7.

I also ran a higher resolution test to see how the frequency of the lowest real eigenmode responded to changes in ratioR over this region.  The plot generated is also attached with a maximal (most favorable) value of 7210.0 Hz at ratioR=0.74.

Data from both of these runs is included in the attached tarball stored as txt files delineated by tabs.

The next few things to try are substituting silicon for fused silica as the material in the model and seeing how the curves change and seeing the response from reversing the orientation of the optimal test mass (ratioR~0.72).  I expect that the orientation change will result in much higher noise and a lower minimal real eigenfrequency.

Attachment 1: UmaxValuesVsRatioR.png  5 kB  | Hide | Hide all
UmaxValuesVsRatioR.png
Attachment 2: FrequencyLowestEigenmodes.png  14 kB  | Hide | Hide all
FrequencyLowestEigenmodes.png
Attachment 3: data.tar.gz  16 kB
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