# Continued Light Blogging

Sorry guys, but the light blogging is going to continue for a while. I’ve got some ideas I’d like to write a bit about, but getting my thoughts together to a point where they’d be worth posting is going to take longer than I have at the moment. Here’s a random sampling of the craziness that is my life:

Things are going fairly well at work, and I should be to the point where I can write up an official MSS Update either sometime later this week or early next week.

Last year I was asked to serve as a Webelos (Cub Scout) Den Leader for the three Wards here in Tehachapi. I finally got formal training for the position last month, and then was promptly released last week, and given a new (and probably more challenging) calling. I’m now the “2nd counselor” in the Elders Quorum for our Ward (Wikipedia has a semi-decent explanation for those not familiar with LDS jargon). It’ll be a challenge, but an enjoyable one.

My thesis is actually moving forward a bit. I was able to get access to Maple (the computer program I’m using for doing my math models) again, so I’ve been making some progress getting my models put together. I was able to tie in the complex loss constants into my piezoelectric vibration model. It turns out that Maple eats Bessel functions with complex arguments for breakfast. I was also able to figure out a model for the pressure distribution in the nozzle (as a function of position, time, and the amplitude of the wall vibration). Interestingly enough, it turns out that you can actually have a negative pressure value in some cases. At first I thought that this meant that the fluid would cavitate at that point, but it turns out you can have negative pressure without cavitation in some instances. Weird, huh? Where I’m having trouble is coupling those two models together (the one that describes the piezoelectric crystal and nozzle with the second model that involves the nozzle wall and the actual fluid). Maple doesn’t like that. Or more correctly, I keep crashing the program as it sits and crunches on the numbers. I’m making some progress, but the math is just really, really, really ugly. I’ll go into the math a bit in a future post if anyone is masochistic enough to want to see it, but suffice it to say, my computer doesn’t like me a the moment.

And on the homefront, I have a wonderful wife, and two cute little boys doing cute little boy things. I’ll have to post some pictures with the incriminating evidence from Jonny’s latest adventure sometime soon too.

Anyhow, but other than some thesis related stuff, and maybe some Jonny bloggin, I’m not going to be able to blog too much anytime soon.

Sorry.

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#### Jonathan Goff

President/CEO at Altius Space Machines
Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.

#### Latest posts by Jonathan Goff (see all)

Jonathan Goff is a space technologist, inventor, and serial space entrepreneur who created the Selenian Boondocks blog. Jon was a co-founder of Masten Space Systems, and is the founder and CEO of Altius Space Machines, a space robotics startup in Broomfield, CO. His family includes his wife, Tiffany, and five boys: Jarom (deceased), Jonathan, James, Peter, and Andrew. Jon has a BS in Manufacturing Engineering (1999) and an MS in Mechanical Engineering (2007) from Brigham Young University, and served an LDS proselytizing mission in Olongapo, Philippines from 2000-2002.

### 3 Responses to Continued Light Blogging

1. Monte Davis says:

Bessel functions with complex arguments

Are these hyperbolics — the ones they used to call MacDonald functions back when we did charcoal math on cave walls?

If so, I don’t blame your computer for getting snarky. Obviously Nature intends such matters to be either fudged with a Taylor series expansion, or passed by in discreet silence.

Speaking of wrestling with complexity, check this out — both pretty and promising:
http://web.mit.edu/newsoffice/2007/turbulence.html

2. mz says:

Sounds complex.

I think Maple behaves pretty well over telnet/ssh, you could try having an access to some other computer (at university) that you can crunch the numbers with.

Eyeballing graphs is harder though, you need winaxe for remote X or save to picture and transfer via sftp. (I’ve done the latter a bit with matlab, it only works if you really know what you’re doing and don’t need to do many graphs.)

3. Jon Goff says:

Mz,
I’ve made some more progress since the post. I found that solving for the impedance and the wall displacement amplitude with one given frequency works just fine. So I’m setting up a loop that runs those numbers at a series of frequencies of which I’m interested. I’ll see how that goes. If that works out, I may be almost there….

~Jon