cartoon

Audio Club special meeting

Tue, Nov 6 at 8:00 p.m. in 3043 Coover.

Tim Lindquist will be presenting the project that he completed for his M.S. degree. He will discuss various audio synthesis techniques and then describe and demo the hybrid synthesizer that he built from scratch. It will be awesome – you should try to attend!


Not voting doubles the value of someone else's vote.

David Foster Wallace, in 2000:

"If you are bored and disgusted by politics and don’t bother to vote, you are in effect voting for the entrenched Establishments of the two major parties, who please rest assured are not dumb, and who are keenly aware that it is in their interests to keep you disgusted and bored and cynical and to give you every possible psychological reason to stay at home doing one-hitters and watching MTV on primary day. By all means stay home if you want, but don’t bullshit yourself that you’re not voting. In reality, there is no such thing as not voting: you either vote by voting, or you vote by staying home and tacitly doubling the value of some Diehard’s vote."

So go vote on Tuesday.


De-construct rather than demolish.

I've always wondered why we can't more of this – when a building is no longer needed or serviceable, it could taken apart piece-by-piece and the useful bits recyled. The usual approach is to flatten the whole thing and haul the wreckage to the landfill. I realize that it is currently cheaper and faster to crunch up an old house and toss the remnants in a hole. But maybe it is time to re-think the economics of simply junking everything. That may include making it more expensive to pile our trash into giant holes, but it would probably also involve changing building practices so that buidings are easier to take apart with their lifespan is over.

The process of demolishing a house is pretty standard these days. I see it frequently around town – most recently the old house on 6th street that was razed to make may for a new downtown Fareway store. First a fence goes up around the doomed house. Then maybe a few windows are pulled out of it and tossed into a dumpster. Then one evening a huge backhoe is parked ominously next to building. The next day, if you happen to pass by, the backhoe will be turning the house into splinters and loading the refuse into trucks that make the trip to the dump on the east end of town. If you miss the action during the day, and only pass by the next evening, then everything wiil be gone – the house, the basement, the backhoe, and the trucks. One day a house, the next day an empty lot – it's rather amazing and a little sad.


World's longest bridge opens.

The new bridge is 55 km long and connects Hong Kong, Macau, and mainland China.


Harry Potter homecoming dance.

All the Harry Potter fans should like this. It's pretty good for a bunch of high-school punks.


People who remember every second of their lives.

I find this absolutely fascinating.


We are running out of quantum computer researchers.

Maybe we need to revive EE 439. We didn't teach quantum computing in that class, but we did teach quantum mechanics, which would seem to be a necessary first step on the way to becoming a Q.C. researcher. On top of that, quantum mechanics is great fun.


Stolen colon

What kind an ass would steal a colon? And more curiously, why would anyone make such a thing in the first place?

(Thankfully, the giant poop chute has been recovered.)


Awww. Sesame Street's Big Bird has retired.

So has Oscar the grouch.


iPhones poisoned by helium

Here's a mystery – a number of recent-vintage iPhones simultaneously quit working at an MRI facility. No other phones, just iPhones and only newer ones. What gives?

The working theory is that they were disabled by helium gas. How could this be!? Here is a sequence of relevant facts that point to the conclusion.

  1. MRI machines use large amounts of liquid helium. During operation of the machine, some of the liquid evaporates. If the generated He gas is not vented properly, it is possible that the local concentration of He in the air may be increased significantly. The normal concentration of helium in air is about 5 parts per million. Even if the concentration were increased a hundred or a thousand times, our bodies would not notice. But some of our devices might.
  2. All electronic gadgets that use microcontrollers or microprocessors need system clocks to operate, and the clocks require control elements to set the frequency. Traditionally, quartz crystals have been used for this purpose. Quartz oscillator chips are used in the vast majority of digital systems that need precise clock frequencies.
  3. Sometime in the last few years, Apple began using MEMS frequency control elements in their phones and watches. MEMS (MicroElectroMechanical Systems) are ultra-small mechanical devices made from silicon. The feature sizes of the mechanical structures are in the micron range, and they are built with the same fabrication methods as used for silicon integrated circuits. (Past EE 432 students might be nodding their heads in recognition.) Basically, the MEMS devices are tiny little tuning forks vibrating at very specific frequencies. They can be used in place of traditional quartz chips to set clock frequencies. A MEMS oscillator is probably smaller than a corresponding quartz oscillator and more easily integrated with the associated clock circuitry. In the constant drive to make electronics smaller and more efficient, it makes sense that system designers would be switching over to MEMS oscillators.
  4. The MEMS oscillators are placed into tiny vacuum-sealed packages to keep air molecules away from the vibrating slivers of silicon. Bumping into O2 or N2 molecules would damp the vibration of the miniature tuning forks, causing the frequency to change. An unstable clock would probably cause the entire digital system to crash. The vacuum seals in MEMS oscillator packages are certainly very effective at keeping air out, otherwise they would never work.
  5. However, He atoms are much smaller than O2 or N2 molecules – so small that they probably pass right through the materials that are used to seal out the air. Anyone who has worked with vacuum systems (that would include me) knows about the difficulty of dealing with helium and hydrogen.
  6. In the presence of elevated He concentrations, it is possible that enough He leaked through the seals of the MEMS oscillator packages that the clocks failed and the system subsequently crashed.
  7. The crashed phones are not necessarily ruined. If removed from the presence of the excess helium, the atoms inside the MEMS oscillator package would eventually leak back out, and the phone or watch would probably start working again. (But it might take several days.)

At first glance, iPhone helium poisoning seems like a far-fetched notion. But in fact, Apple acknowledges the possibility of exactly that in iPhone user guide, warning that "Exposing iPhone to environments having high concentrations of industrial chemicals, including near evaporating liquified gasses such as helium, may damage or impair iPhone functionality." Although not been proven beyond a shadow of a doubt in this particular case, it does seem likely that a few rogue He atoms brought down all of those expensive phones at the medical facility. So there you have it – if you use an iPhone (or any other device that uses MEMS oscillator parts), watch out for helium!


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