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ME 431: Mechanical Vibrations

thoughts on vibrations...
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I added some more to the notes, specifically on the unforced solution to a spring-mass-damper system. In exchange for these tidbits(external link) of knowledge, I'd like to ask for your comments. I'm creating these on my tablet(external link), so I can go back and make changes, corrections, and additions. Is there something that's confusing or lacking detail? Let me know.

Lyric of the day
It's that clean, clear truth that sorts our the wrong from the right.
You and your face of light(external link).

Welcome back...

A few annouoncements:
  1. In an attempt to escape the bowels of Buckingham, the classroom has been tentatively changed to ASEC 304. Ideally, we will find a larger room but that remains to be seen. Hopeful I am not.
  2. I added the notes on mechanics (ME431-notes.pdf) to the website, under the ME 431 Notes page, surprisingly enough.
  3. The University seems to be having network issues. Not sure why, but hopefully it will be fixed soon. So if you can't access this website in the future, be patient and try again. Obviously you are reading it now, so at worst the connectivity is intermittent.

Lyric of the day
Hold my hand
Ooh, baby, it’s a long way down to the bottom of the river(external link).

Hi all,

Due to the snow days I am going to extend the homework due date to Monday. However, the solutions will still be made available on that day so there will be no late homework accepted. Also, the quiz that was scheduled for today will be held on Friday instead.

-dq
...and the project description is available(external link).

The basic idea is to attempt to the model the mechanical vibrations that produce the sound from stringed instruments, such as a guitar or banjo. Also, instruments such as violins, violas, cellos, or even pianos can be modeled in this way. You can find a number of references regarding this approach at and I'm sure that many more exist (I just did a quick Google search and only looked at the first couple of hits).

Once you come up with your model, we can then use MATLAB to generate the resulting sound with the command
sound(x)
where x is the vector that describes the sound signal (use help sound for more information). As an example, I wrote a little MATLAB file, twinklemidi.m(external link) to illustrate this capability within MATLAB.
The first homework has been posted on the website(external link). There are several problems from the book and two more that I have taken from elsewhere. These are all material that you have seen in previous classes, including Dynamics and SD&R, but it never hurts to review...
In case anyone is interested, a couple of random thoughts...

There is a new textbook for this class. The previous book is now out of print so we could not get enough copies to meet the enrollment, hence the new book. However, the course will be focused on the lectures, rather than the book. I remember as a student hating the professors who would essentially read from the text and then work examples from the text. I always wondered why then I didn't just do the same from the comfort of my room. So I try to present the material in the whatever way I think you will be best served, instead of how the author of the text thinks is best.

Having said that, the current book by Balachandran (who happens to be a friend of mine) is pretty good. It has a number of modern examples and incorporates numerics with MATLAB. We will do the same.

Also, we'll have a project in this course. Hopefully a pretty cool one at that. In the past I have done projects of the vibrations of zeppelins(external link), the control of a Segway(external link), energy harvesting(external link), and deformable mirrors(external link). I am currently thinking about this semesters project. Any cool applications come to mind?


I've been motivated to get this started by a friend of mine, Ed Berger(external link), at the University of Virginia who started his own, HigherEd 2.0(external link), some time ago and finds it to be an effective way of communicating with his students (or so he says...thanks Ed). Ed has also done a number of other interesting things with Web2.0 technology.

The goal of this is to find ways to interact with not only me but each other as well. I guess we'll see how it goes, but I'm very excited that we can make this work. Ideally, this site will be sort of a central meeting point outside of class...and eventually it could take on a life of its own.

You can ask questions of me and each other about just about anything...vibes-related(external link) or not(external link)...

This site is run by the TikiWiki(external link) software. I am very new to this and I'm not quite sure exactly what I've gotten myself into. However, this seems like it has just about everything: blogs, a wiki, galleries, articles, and several other things that I have not enabled. Very powerful stuff. I really have no idea how we will use all of this, but then again, that's the point.

So here it is...and it should become whatever you want it to be...


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