 Wed Aug 2 13:47:47 2017, Zach, Electronics, Modeling, Arm width Sweep 
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2017-08-02
I ran a sweep of the width of the ESD arms. There appears to be a linear relationship across the modes except for mode
25. Mode 25 exhibits a very similar behavior as in the arm gap sweep. I realized that the abrupt change in direction (also noticeable in mode 14) is likely
caused by the fact that the force profile is calculated as absolute value, there might be an exponential relationship that gets converted into that shape |
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Wed Aug 2 15:40:00 2017, Zach, Electronics, Modeling, Parameter diagram
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I am posting a diagram of the geometric parameters that I swept. The only one not included is the vertical space between the ESD and sample that sweeps
perpendicularly out of the image
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Mon Aug 7 13:19:48 2017, Zach, Electronics, Modeling, Normalized data
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2017-08-07
I included the modal mass factors in the code and renormalized my data. The normalization has a noticeable impact, but
does not change the general trends of the data
In fact the impact is not even significant enough to warrant a change in the ideal parameters
I picked for the rectangular ESD in my interim report
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Tue Aug 8 16:20:24 2017, Zach, Electronics, Modeling, Rotated ESD
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2017-08-08
I rotated the ESD and calculated it's modal projections by rotating the data array that MATLAB extracts from COMSOL.
I confirmed that this was properly done by plotting the profile and then computed and plotted both the rotated and normal projections.
The rotated
ESD actually increases the force in some of the modes but decreases the forces in others. It markedly improved the force in 7 of the modes: 3, 6, 12, 18, |
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Wed Aug 9 12:10:47 2017, Zach, Electronics, Modeling, Preliminary improvement from ESD optimization
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2017-08-09
I created a plot of the ratio of the force in the optimized design to the force in the original design. The improvement
factor is huge, some modes are excited by more than a factor of 100. I took the same ratio keeping the gap between the ESD and the sample constant and
it decreased the excitation by almost a factor of 10. Keeping that gap constant, the geometric modifications to the ESD give an improvement factor ranging |
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Wed Aug 9 15:57:28 2017, Zach, Electronics, Modeling, Triangular Geometry
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2017-08-09
I compared the triangular geometry to the original geometry and the excitation was only improved in 7 of the of 20
modes. In four of those modes the improvement factors ranged from almost 2 to over 3 while the other modes where only improved by about 25%. The other
13 modes were diminished drastically, 9 of them where less than half as excited. Given more time it may have been interesting to try and optimize |
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Wed Aug 9 17:07:57 2017, Zachary, Electronics, Modeling, Optimization Summary 6x
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2017-08-09
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From the data I have gathered from a variety
of MATLAB sweeps, I think that the optimal geometry I can produce has the parameters in the attached image. Neither the original or optimized drawing is |
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Thu Aug 10 10:47:54 2017, Zach, Electronics, Modeling, Geometry Ratios
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2017-08-10
The attached plots compare the new and old geometries with .5 mm and 1 mm sample gaps. They are the same plot on linear
and logarithmic axes respectively
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Tue Aug 15 00:09:01 2017, Zach, Electronics, Modeling, ESD Improvements 10x
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2017-08-14
I did my best to increase the excitation in the higher order modes. By making the ESD narrower (a 6mm electrode overlap)
the higher order excitation is improved drastically, by factors of between 10 and 30 for most modes. I also created a double ESD (see image) that
excited the modes by a factor of 3 or more better than the thinner drive. The plotted ratios are relative to the original geometry, but both of these geometries |
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Tue Aug 15 16:43:58 2017, Zach, Electronics, Modeling, Unchanged Mode Insight
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2017-08-15
It appears to me that the major factor limiting the improvement of the modes that either remain equal or diminish is that
the original design was already quite good at exciting those modes. As can be seen in the attached plots, the original design is about as well centered
over the 5 modes as a rectangle on the x axis can be. As a result, maintaing a constant potential on the ESD it would be difficult to improve the coupled |
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Wed Aug 16 10:04:24 2017, Zach, Electronics, Modeling, ESD along edge
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2017-08-16
I placed created a very narrow ESD placed along the edge of the sample. The thought behind this is that it will not cross
over into any other modes that will cancel out the force. However, it does not appear to couple force into enough of the area of the disk to cause a worthwhile improvement,
as can be seen in the plot, more modes lost amplitude than gained and some were worse by as much as a factor of 1000.
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Wed Aug 16 11:36:13 2017, Zach, Electronics, Modeling, Middle ESD
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2017-08-16
I created a model with a drive offset in the middle. It improved one of the modes by a factor of 14 or so, but overall,
it diminished the vast majority of the modes by as much as a factor of 100.
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Wed Aug 16 16:05:09 2017, Zach, Electronics, Modeling, Two ESD First test
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2017-08-16
I created a model with two ESD's, essentially a combination of my previous two attempts with one ESD on the edge and
one closer to the center of the disk. This test was quite successful compared to previous trials, the improvement seems to be on an average of a factor
of 10. No modes are weakened by this design. I am going to run a sweep adjusting the central ESD and see what placement is best.
Attached is |
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Thu Aug 17 14:19:04 2017, Zach, Electronics, Modeling, Two ESD Optimization 17x
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2017-08-17
I ran a sweep of the position of the middle ESD to determine the optimal arrangement. From the original geometry I offset
the central ESD between -2 mm and 11 mm. From the plots below I conclude that the optimal geometry is the one that is shifted 2 mm to the right of the
original design.
The first plot is the sweep data as a ratio to the data of the current geometry for all modes. The second plot is the |
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Thu Aug 17 23:34:51 2017, Zach, Electronics, Modeling, Optimized ESD Drawing
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2017-08-17
I made a drawing of the Optimal ESD design. The bottom combs (right hand in the rotated image) are set to ground and the
5 arm comb is set to a positive voltage and the 2 arm comb is set to a negative voltage.
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Fri Aug 18 10:50:53 2017, Zach, Electronics, Modeling, ESD's with positive voltage
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2017-08-18
With both electrodes driven at a positive voltage, the results are still an improvement over the original design, but
by smaller factors, particularly in 3 of the higher frequency modes at around 2 and 3 kHz. With another parametric sweep I may be able to find a better
design. The opposite voltage was useful because it could couple force in opposite directions to adjacent anti-nodes with opposing signs. An adjusted configuration |
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Fri Aug 18 14:15:47 2017, Zach, Electronics, Modeling, Same Voltage ESD Sweep
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2017-08-18
I ran a sweep of the central position in the two ESD setup with both set at the same voltage. There were two designs that
maximized excitation by different metrics, the design with a 3 mm shift from the original design maximized excitation overall, but the 20 kHz mode was
worse by a bout a factor of 5. The design with a -2 mm shift maximized the high frequency modes, particularly the modes most affected by the shift.
MATLAB |
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Fri Aug 18 15:10:23 2017, Zach, Gabriele, Electronics, Modeling, ESD prototype
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2017-08-18
We created a prototype of PCB for the ESD design. Unfortunately the orientation of the two combs was flipped, so it will
require some creative mounting to get right. The final design had a 6 mm offset between the two combs, .5 mm traces and 1 mm gaps between them The vertical
traces are 12 mm long and there is a 3.75 mm gap between the end of the vertical traces and the opposite horizontal one. The ESD will arrive on Tuesday |
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Wed Aug 23 14:11:13 2017, Zach, Gabriele, Electronics, Measurements, Installing ESD Prototype
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2017-08-23
Installed ESD Prototype design by taping it to the older design, we then lowered the mount until it was as close as we
could reasonably get it. The new PCB lines up when the top of the new PCB is lined up with the last electrode on the old one. The new PCB was slightly
too narrow, the mounting holes are very close to the edge of the PCB, this can easily be corrected in later models.
Installed sample |
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Tue Jan 30 15:56:36 2018, Gabriele, Craig, Electronics, Configuration, Temporary data acqusition for PSL lab beat note and accelerometers
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We set up the model x3tst to acquire at 65kHz four signals coming from the PSL lab:
X3:TST-BEAT_OUT_DQ: beat note
X3:TST-ACC_X_OUT_DQ: accelerometer X
X3:TST-ACC_Y_OUT_DQ: accelerometer Y
X3:TST-ACC_Z_OUT_DQ:
accelerometer Z
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Mon May 2 11:46:45 2016, Gabriele, Facility, Daily Progress, Table and vacuum chambers in the lab
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Elogs for the new Coatin RIng-down MEasurement lab had to start somewhere, so here is a couple of pictures of the optical table with shorter legs and
of one of the two vacuum chambers that have been moved in. |
 Tue May 3 11:57:47 2016, Gabriele, Facility, Daily Progress, Table and vacuum chambers in the lab
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We discovered a couple of days ago that the table was sitting on three legs only and the fourth one was dangling. I managed to adjust the height of the
fourth leg using the large screw on the leg support. Now the table is properly supported by all four legs.
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Tue Jun 7 14:07:55 2016, Gabriele, Facility, General, Rack and workstation
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I moved the unused rack from the Crackling Noise lab to the C.Ri.Me lab. It will be used for the new cymac. I also started putting the new workstation
together, but I'm missing some adaptors for the monitors.
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Thu Jul 7 17:44:11 2016, Gabriele, Facility, Daily Progress, Vacuum chamber tests
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[Alena, Gabriele]
This afternoon we opened the tall belljar vacuum chamber, and took everything out of it. All the stuff that was inside the chamber is "temporarily"
stored on the floor beside the optical table. |
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Fri Jul 8 15:26:37 2016, Alena, Facility, Daily Progress, Vacuum chamber tests
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Fixed the 307 gauge controller (a missing contact on the rair panel). The low pressure gauge was connected to 1G port and has measured 1.7E-6 torr. We
are not sure since how long the turbo was operating (no vacuum logger yet).
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Mon Jul 11 14:56:45 2016, Alena, Facility, Daily Progress, Vacuum chamber tests
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Installed a gate valve between the roughing and tubbo pump. See below a pump down curve. The convection gauge is not calibrated. the turbo started at
14th min (at about 3 torr) |
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Mon Jul 11 17:04:06 2016, Alena, Facility, Daily Progress, Vacuum chamber tests
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At 5pm the pressure was 6.5e-6 torr.
Checked again at:
9am, pressure was 2e-6 torr
11:30am, pressure was 1.5e-6 torr
5pm, pressure was 1.4e-6 torr
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Thu Jul 14 16:56:00 2016, Alena, Facility, Daily Progress, test vacuum system
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| Please see prosidures for pumping down and venting with air for the test vacuum chamber here https://dcc.ligo.org/T1600304 |
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Sat Jul 16 14:15:44 2016, Gabriele, Facility, Daily Progress, Pump down started
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Following Alena's procedure, at about 1:30pm LT I started the chamber pump down. At
14:15pm LT the pressure was still 240 mTorr
At 6:20pm the pressure was about 70 mTorr, so I started the turbo pump. |
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Mon Jul 18 13:39:45 2016, Gabriele, Facility, Daily Progress, Pump down started
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Today at 1:40pm pressure is 8.5e-7 Torr
Quote:
Following Alena's |
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Tue Jul 19 17:15:37 2016, Gabriele, Facility, Daily Progress, Vacuum pressure acquired
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[Alena, Gabriele]
We connected the analog output of the vacuum gauge controller to one of the ADC channels. The signal is calibrated so that the pressure is 10^(X3:CR1-PRESSURE_LOGTORR_OUT).
Unfortunately the RTG does not know how to compute 10^x... |
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Wed Jul 27 11:27:11 2016, Gabriele, Facility, General, Pumps stopped and venting
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11:25am LT: closed valve between roughing and turbo pumps, switched off both pumps. Turbo pump is slowing down
After lunch I opened the chamber and removed everything from the inside.
The chamber around the vacuum gauge is really dirty now, see picture: |
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Wed Jul 27 15:43:02 2016, Gabriele, Facility, Daily Progress, Vacuum chamber dismantled and ready for cleaning
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[Alena, Gabriele]
As decided at out Red Door meeting, we're going to clean the vacuum chamber and move it to the large table, which will be enclosed in a clean
room. |
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Sat Aug 13 11:17:17 2016, Gabriele, Facility, Daily Progress, Spot the differences
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Fri Aug 19 13:46:55 2016, Alena, Calum, Jon, Liz, Steve, Gabriele, Facility, Daily Progress, Clean room and vacuum complete
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This morning we installed the clean room curtains and washed them. It turns out that the air filters are supposed to be powered at 277V (?) instead of
115V. So right now the flux is quite low. We are looking into the problem: either replace them with 115V modules or install a small transformer.
We also installed the vacuum chamber on the table and connected all the pumps and gauges. There are no leaks and we could pump down easily the |
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Thu Sep 15 11:23:13 2016, Gabriele, Facility, General, Chamber open
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Turbo pump off and spinning down at 9:37am LT. Pumo completely stopped at 11:15am LT
Openend the chamber and removed the sample at ~11:20am LT |
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Mon Sep 26 15:54:01 2016, Gabriele, Facility, Configuration, Moved vacuum controllers
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I moved the turbo pump controller out of the clean room. Also, I installed the gauge controller on the Cymac rack.
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Tue Nov 29 17:02:06 2016, Gabriele, Facility, Noise hunting, Suspending the roughing pump
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I suspended the roughing pump with four springs. The reduction of the 58 Hz peak is similar to what I got when the pump was sitting on a box. So most
of the coupling is due to acousting noise.
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Thu Jan 19 12:49:17 2017, Gabriele, Facility, Vacuum, Skyhook installed
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The SkyHook has been put in place and bolted down to the floor.
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Thu Sep 14 15:59:10 2017, Gabriele, Facility, , All wrapped up for Saturday plumbing work
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Wed Jun 29 16:44:17 2016, Gabriele, General, Configuration, First disk eigenfrequency
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The following table shows the lowest eigenfrequency (Hz) for different sizes of disks
Diameter \ Thickness [mm]
0.125
0.250
0.500
1.000
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Mon Jul 11 15:21:12 2016, Gabriele, General, Daily Progress, One disk installed into the chamber
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[Alena, Gabriele]
We attached one of the silicon lenses to a 1" optical post using some kapton tape, and installed it into the vacuum chamber. We built a
simple periscope using standard optical component, and managed to send the optical level beam into the disk and back out. |
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Fri Jul 15 17:56:50 2016, Gabriele, General, Daily Progress, QPD connected to digital system
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I connected the QPD to the ADC interface with a temporary cable running on the floor.
I could get signals. I still have a problem with the digital system: I can't access test points with dataviewer, but I get them with DTT.
This will have to be fixed. |
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Mon Jul 18 14:29:07 2016, Gabriele, General, Daily Progress, Status of the test setup
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I checked that the QPD electronics works as expected, and that I can acquire the signals using the ADCs. A new model (x3cr1) is up and running. It acquires
the four quadrants, convert them from counts to volts, and compensate for the analog whitening filter. The four quadrant signals are X3:CR1-Q1_OUT, X3:CR1-Q2_OUT,
X3:CR1-Q3_OUT, X3:CR1-Q4_OUT. |
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Mon Jul 18 17:46:04 2016, Gabriele, General, Daily Progress, First look at QPD signals
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Here's the first spectrum of the QPD X and Y signals, acquired with the digital system. Roughing and turbo pumps are still on.
The noise floor seems quite non stationary. To be investigated.
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Tue Jul 19 17:21:48 2016, Gabriele, General, Daily Progress, First modes excited!
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We can't generate any arbitary signal with the real time model, since awg is not working properly yet. For the moment being I added a uniform random
number generator in the model (only option I found for noise) and send it into the ESD filter bank. In this way I can generate band-passed noise.
I plugged in the DAC output to the HV amplifier input, and I could send white noise to the electrostatic drive. Behold: I was able to excite |
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Thu Jul 21 12:10:14 2016, Gabriele, General, Daily Progress, Glitch hunting
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Yesterday I could clearly see the glitches as jumps in the time domain plot of X and Y signals, and trace them to somewhat harder to see jumps in the
quadrant signals.
I tried to catch them with an oscilloscope looking at the analog signals, but couldn't see any. However, for a brief period I had |
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Thu Jul 28 14:01:27 2016, Alena, General, Daily Progress, Clean room
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| Ordered the clean room (hardware+hepa filters) and vacuum gauges |
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Fri Jul 29 14:08:31 2016, Gabriele, General, Daily Progress, Peak tracking code for real time model
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Summary
I wrote a C function to reconstruct the amlplitude and frequency of a line. It can be added as a block into a real time monitor.
The idea is to use it to track in real time the frequency and amplitude of the disk modes, during the ring down. I did some tests and finally managed to
get the function to compile and run on the cymac2 (the crackling lab cymac). |
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Mon Aug 8 10:42:46 2016, Gabriele, General, General, Dependency of eigenmode frequencies on thickness and diameter 26x
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I ran a set of COMSOL simulations to determine the dependency of the frequency of each eigenmode on the disk thickness and diameter, within the tolerances.
I chose wide ranges: diameter 75.0 +- 0.1 mm and thickness 1.0 +- 0.1 mm, much more than the expected tolerances. It turns out that the frequencies depends
almost exactly linearly on both variables: mostly on the thickness and negligibly on the diameter. The following plots shows: the mode shape and frequency (left), |