40m QIL Cryo_Lab CTN SUS_Lab TCS_Lab OMC_Lab CRIME_Lab FEA ENG_Labs OptContFac Mariner WBEEShop
  COMSOL elog  Not logged in ELOG logo
Message ID: 59     Entry time: Mon Jul 15 13:14:30 2013
Author: Emory Brown 
Type: Optics 
Category: General 
Subject: Umax curves for varying height test masses 

 I ran sweeps over the ratioR range from 0.5 to 0.9 for test masses with modified height, and thus mass, which were otherwise equivalent to our previous test mass.  The attached plot was generated and indicates that the optimal ratioR value for the test mass was shifted significantly, for the half mass test mass into lower frequency regions, and for the 10x mass test mass into higher frequency ranges.  I took the data collected from the half mass run and fit a polynomial of degree 2 to it in Matlab using the command p=polyfit(x,y,2) and obtained p=1.089*10^-10*x^2 - 1.024*10^-10*x +1.774*10^-10 which has a minimum value for ratioR=0.47.  This fits with the plot generated as it appears to be near its minumum value, but I should run the simulation more around this value to see if it fits the expected behaviour.  I also did this fitting for the 10x mass curve, but based on the greater variance in the curve over this region of ratioR values I don't expect the predicted minimum to be as accurate, so if we want to find it we will have to search that region of ratioR values. For the 10x mass test mass, p=4.459*10^-10*x^2 - 8.859*10^-10*x + 6.289*10^-10 which has a minimum of about 1.

I will run simulations in these regions overnight, and edit this post with the plots/results.

Attachment 1: MassComparison.png  16 kB  | Hide | Hide all
ELOG V3.1.3-