The Tube of Terror

March 27, 2012

June 16th is the second annual Nevada City Adult Soapbox Derby, where grown men (and some women) raise money for Pioneer Park, by spending ridiculous amounts of time building gravity-powered vehicles.

Here’s the local hospital entry from last year:

This year, since I’ve got so much free time, I decided to put together a team. Thus was born the “Tube of Terror”, sponsored by Scale Unlimited. With the aid of some people who actually know how how to design and build things, I’m hoping we’ll be competitive in the speed category.

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Whatever Happened to the MIT Delts of ’83 – Revised

November 22, 2011

Almost four years ago I’d written a blog post about the members of my MIT fraternity class – Whatever Happened to the Class of ’83

I thought I’d revisit that theme, but now with an updated class composite photo, using images taken during a recent 50th birthday event hosted by Jono Goldstein at his place in Cape Cod.

MIT Class of 1983 Composite

Updated details to follow, when I get some time…


Interesting dates in computer programming

July 15, 2011

Everybody knows about the Linux “epoch”, as in January 1st, 1970 UTC.

Some people might remember the original Mac OS equivalent, which was January 1st, 1904. From what I remember back in the day, Jerome Coonen picked that date (instead of 1900) because it simplified the leap year calculations. And using an unsigned 32 bit value for seconds meant that Macs could handle dates up to 2023 or some point way in the future.

Then yesterday I came across the MUMPS/Cach√© “$h” date format, which is described as:

This format returns the date as the number of days since 1st January 1841, and the time as the number of seconds since midnight.

I was speculating with my friend as to why they picked 1841, and guessed that this was some convenient date (similar to the Mac 1904 choice) that was before the birthdate of the oldest person they could imagine being in the system, back in the 1960s.

After turning to the Source of Truth (Wikipedia’s article on MUMPS), it seems like our guess was correct. James Poitras explains why he picked this odd date:

I remembered reading of the oldest (one of the oldest?) U.S. citizen, a Civil War veteran, who was 121 years old at the time. Since I wanted to be able to represent dates in a Julian-type form so that age could be easily calculated and to be able to represent any birth date in the numeric range selected, I decided that a starting date in the early 1840s would be ‘safe.’ Since my algorithm worked most logically when every fourth year was a leap year, the first year was taken as 1841. The zero point was then December 31, 1840


Maiden voyage of Garmin foretrex 401

July 10, 2011

I finally got a chance to try out the new Garmin wrist-mounted GPS unit that my friend Stefan gave me.

Pretty sweet – it does a good job of tracking, even in the foothills of the Sierras, where GPS signals come and go.

I wish I could directly embed the map of the hike, but that requires an , which isn’t allowed by wordpress.com – oh well. You can still click here to view it on the garmin.com site.


What is Big Data, and why you could care

January 8, 2011

That’s the title for my talk this coming Thursday¬† night (January 13th, 2011), at the first “Tech Talk” sponsored by Sierra Commons. Details are at http://sierracommons.org/2011/local-business/2108.

Erika Kosina has done a great job of setting this up, and I’m looking forward to meeting more of the local tech community.

Some of the things I’ll be touching on are:

  • Why big data is the cool new kid on the block, or why I wished I really knew statistics.
  • Crunching big data to filter, cluster, classify and recommend.
  • How big data + machine learning == more effective advertising, for better or worse.
  • The basics of Hadoop, an open source data processing system.

Hope to see you there!

 


Big Data talk for technical non-programmers

December 22, 2010

I’ve going to be giving a talk on big data for the newly formed Nevada County Tech Talk event – a monthly gathering at Sierra Commons.

Unfortunately most of the relevant content I’ve got is for Java programmers interested in using Hadoop. Things I could talk about, based on personal experience:

  • A 600M page web crawl using Bixo.
  • Using LibSVM to predict medications from problems.
  • Using Mahout’s kmeans clustering algorithm on pages referenced from tweets (the unfinished Fokii service).

I’m looking for relevant talks that I can borrow from, but I haven’t found much that’s targeted at the technically minded-but-not-a-programmer crowd.

Comments with pointers to useful talks/presentations would be great!

 


New power supplies sometimes don’t work with old MacBooks

August 11, 2010

Recently I had to buy a new power supply for my 2008 MacBook. Because having three adapters isn’t enough, when you forget to bring any of them with you on a business trip.

So I ran into the Apple store in San Francisco and grabbed a new 60 watt adapter – the one with the “L” style MagSafe connector, versus the older “T” style connectors I’ve got on my other three adapters.

Raced back to the client. Plugged it in – and it didn’t work. Spent 20 minutes cleaning my connector, trying different outlets, etc. No luck.

Headed back to the Apple store, and verified the following:

  • My new adapter works with three different MacBooks on display.
  • None of the 60 watt power adapters with “L” style connectors being used for display Macs worked with my MacBook, but all of the 60 watt adapters with older “T” style connectors did work.
  • The 85 watt power adapter at the Genius Bar did work with my MacBook.
  • The new 85 watt power adapter that Mitch @ the Bar set me up with didn’t work with my MacBook.
  • The older 60 watt power adapter Mitch extracted from the store’s repair supply stock did work.

After all of the above, I got in touch with a friend who works as a Genius at the Manhattan store. Turns out she’d just had to deal with a similar issue, and the root of the problem is that the System Management Controller (SMC) needs to be reset for some older MacBooks to work properly with new power adapters.

Apple has information about how to reset the SMC, and on that page it lists one of the reasons why you need to do this as “The battery does not appear to be charging properly”.

I’m hoping Apple updates the info found on both this page and their Troubleshooting MagSafe adapters page, to make it easier to find in the future for other users. Before Apple Stores run out of these older “T” style power adapters.