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Profile Travis
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Message 39042 - Posted: 23 Apr 2010, 4:07:14 UTC
Last modified: 23 Apr 2010, 4:08:03 UTC

I'm going to be giving a brief presentation about MilkyWay@Home tomorrow for RPI's Center for Open Source Software (RCOSS) at 4pm in JEC 3117, if you happen to be nearby and want to attend.


But for those of you who cant, which is probably most of you :) I've made the slides available online. Feel free to ask me any questions about them. Here they are:

[keynote] [powerpoint]


--Travis
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Message 39064 - Posted: 23 Apr 2010, 16:54:38 UTC

Thank you for noticing some of us are not office users ... :)

In slide order ...

#3 - are you saying the MW is the third most powerful or BOINC as a whole?

#4 - any idea why the fairly significant drop off in hosts? Are the users like me that dropped CPU processing in favor of only using systems that have a GPU (in my case a loss of 1 of 5)

#6 - Guessing, but image lower left is artist's conception(?) - and the Sagittarius Dwarf is the "knot" in the upper center? with the tails ripped off dust and stars? Or mostly stars?

#7 - will the survey continue to fill in the available areas not obscured by dust, or is this survey "complete" as in ended?

#8 - this is showing a "flipped" view of slide #6? or am I completely missing the point (again)?

#9 - Ok, we calculate what we think the distribution should be with the tasks we run ... then this calculated model is compared with the known mapped distribution? Is this done with star positions or just some sort of matter distribution map obtained by the sky survey mentioned previously.

#10 - even more active is boinc_alpha where the testing and bug reporting for the client happens.

Sorry for the possibly childish questions as was pointed out to me 6 year olds seem to understand these matters better than I, but, can't learn if you don't ask ...

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Message 39072 - Posted: 23 Apr 2010, 19:19:37 UTC - in response to Message 39064.
Last modified: 23 Apr 2010, 19:22:55 UTC

Thank you for noticing some of us are not office users ... :)

In slide order ...

#3 - are you saying the MW is the third most powerful or BOINC as a whole?


1.6 petaflops puts us right behind the 2nd fastest supercomputer in the world, so 3rd most powerful as a whole. We're the #1 BOINC project in terms of computing power (collatz is #2 at 1 petaflop, and SETI is around 800).

For some comparison, the worlds fastest supercomputer is around 1.9 - 2 petaflops, and the second and third are around 1.2 petaflops. top 500 supercomputers list.

Folding@Home is ~6 petaflops.

While catching up to Folding@Home probably won't happen for awhile, a few more GPUs should push us past that #1 supercomputer :D


#4 - any idea why the fairly significant drop off in hosts? Are the users like me that dropped CPU processing in favor of only using systems that have a GPU (in my case a loss of 1 of 5)

I have a feeling the validation changes and downtime were the cause of this. I'm hoping once the new application gets finished and things are running smoothly it should pick back up.


#6 - Guessing, but image lower left is artist's conception(?) - and the Sagittarius Dwarf is the "knot" in the upper center? with the tails ripped off dust and stars? Or mostly stars?

Yeah, the lower left image is an artist's conception. According to the next slide the dwarf galaxy should be in the lower left corner. I think the tails are mostly stars.


#7 - will the survey continue to fill in the available areas not obscured by dust, or is this survey "complete" as in ended?


I think the data we're currently using is from SDSS-II which has completed, but SDSS-III is in the works: http://www.sdss.org/


#8 - this is showing a "flipped" view of slide #6? or am I completely missing the point (again)?

I think #6 is a flipped version of this one :)


#9 - Ok, we calculate what we think the distribution should be with the tasks we run ... then this calculated model is compared with the known mapped distribution? Is this done with star positions or just some sort of matter distribution map obtained by the sky survey mentioned previously.


What the tasks do is calculate the likelihood that a given model -- basically the position of the stream cylinders and a background distribution (stars not in the streams) match the observed stars from the SDSS. We use this likelihood (or fitness) to determine which models we use in our evolutionary algorithms to generate new workunits. Our searches evolve the parameters of the model to find the best fit of the model to the SDSS data for the given wedge.

On a somewhat related note -- the big difference in the new application (milkyway3) is that it can use a new background distribution function. If we have a good model for the background (which is something no one knows right now), it will be very easy to figure out what stars are in tidal streams, and this will also give us valuable information about the distribution of stars within the milky way, which could help in determining what and where dark matter is within our galaxy (hopefully I got that all right).


#10 - even more active is boinc_alpha where the testing and bug reporting for the client happens.

Sorry for the possibly childish questions as was pointed out to me 6 year olds seem to understand these matters better than I, but, can't learn if you don't ask ...


Not at all, thats the point of the site after all, to explain what we're doing. It's good to have some scientific discussion in here ;) I'm going to direct Matt to this thread so he can answer more astronomical questions.
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Message 39075 - Posted: 23 Apr 2010, 20:41:30 UTC
Last modified: 23 Apr 2010, 20:41:39 UTC

As for clarification of slides #6 and #8:

The top right image on slide #6 is a visual picture of the Sagittarius Dwarf galaxy, with some overlays drawn on it. You will notice that it appears just below the center of the galaxy, from our perspective. (indeed, the center of the Milkyway Galaxy is in the direction of the constellation of Sagittarius) The dwarf appears on the far side of the galactic center from the Earth.

The lower left image on slide #6 is really just an artistic representation, to give a sense of scale - I'm not sure if I can see where it penetrates the galactic disk. In any case, the Sag. Dwarf galaxy core is pretty close to being inside the disk of our galaxy.

The graphic on slide #8 is my own creation -no image credit? Shame on you, Travis ;) - I put it together to be as accurate as possible. The Sun should be a little farther away (maybe I'll fix that for future use), but the Sag. Dwarf and tidal tails are nearly in their correct positions.

I hope that I answered you questions, but feel free to ask more!
Cheers,
Matthew

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Message 39088 - Posted: 24 Apr 2010, 3:55:21 UTC

Sadly, we have reached the limits of the ability of my brain to make sense out of what you are saying... :(

I learned long ago that there were some things I just would never be able to "see" ... no matter, one of the reasons I am here is just so you smarter people in this area can figure out what needs to be figured out ... :)

Anyway, thanks for the quick responses and if I can think of more questions I will ask them ... another character flaw ...

In the universe of BOINC, MW is one of the exceptional projects where the staff actually has continued to talk to us both about what is going on with the project in day-to-day things and what the science is ... Einstein used to be this good but have slowly slacked ...

Anyway, thanks again ...


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