Tuesday, March 18, 2014

Saturday, February 15, 2014

Studded Tires OMG

Studded tires make a huge difference. I could ride on 2" of solid ice. The tires literally laughed at snow and slush. Which is surprising because I didn't think they could make any kind of vocalizations, let alone laugh derisively. But it turns out they are quite chatty. They said all sorts of things like: You can go right through that slush. Why are we going so slow? No, I don't want to be put in the garage and forgotten about for 20 years.

Anyway they worked out well.

Friday, February 14, 2014

Studded Tires

We are expecting more snow tomorrow and I'm sick of slipping in the snow when I'm on my bike. So, I bought some studded tires. I'll let you know how they work out. 

Thursday, February 13, 2014

Self Driving Cars

Self driving cars have been in the news a lot lately, especially since Google announced its efforts in the area. Some people think self driving cars will be the end of privately owned cars. If you could have a zip car show up to your door, instead of having to go look for it, why would you want to own one?

There is the emotional reason to own a car but, there is a more interesting reason for owning a self driving car. In places where it snows, it is common for a guy to buy a truck and plow some driveways to offset the cost. There are many opportunities for the owner of a self driving car to use it to make money.

For example: I get to work at 900 and the car drives itself to an Amazon distribution center where it picks up a package ordered by someone who wants same day delivery. The car takes the packaged to the persons house and when it gets there it sends a text message to the person who made the order. The person walks to the car with their cell phone and the trunk pops, they grab the package, shut the trunk and the car go back to the distribution center. The car makes a few deliveries before returning to my parking lot at work at 530, texts me it's location and I walk over to it and go home. Or I tell it to show up in front of the building and I just get in.

That's just one example. There are many more. I could rent it on Wednesdays to a cab service. If I owned a pizza shop I could have it deliver the pizza while I'm at the restaurant making them. Owning car could be an income source like owing rental property.

Saturday, January 4, 2014


Calculating the PSD from the ACS

Let's say we have the autocorrelation sequence (ACS) [0.25 0.5 1.0 0.5 .025] and we wish to  calculate the power spectral density (PSD).  If we use MATLAB and perform the Fourier transform as fft([0.25 0.5 1.0 0.5 .025] ) we will get [ 2.5000 -0.7318 - 0.5317i   0.1068 + 0.3286i   0.1068 - 0.3286i  -0.7318 + 0.5317i]. Since the PSD is a real function, the result cannot be correct. The key is the MATLAB fft function treats the first element of the sequence 0.25 as the the zeroth lag. The correct PSD is calculated as fft([1.0 0.5 .025 0.25 0.5]).

Tuesday, December 31, 2013

Every now and then the story about Chicago's parking meters up. The hard to believe part is they sold the rights to collect income 75 years in the future. Predicting the future is hard. How can you come up with a way to properly value the meters 75 years in the future? Morgan Stanley thinks the city got it wrong by 10 billion or so.

Thursday, December 26, 2013


I just started reading Moneyball. I know so 2003. So far really good. I tells the story of how statistics changed the way decisions are made in baseball. One of the very interesting parts is how long established stats like batting average did not necessarily help answer important questions.