Death Cab for Cutie - "Long Division"

I first listened to this song on a hike at Sleeping Giant about 18 months ago, and listen to it from time to time, especially if I'm doing a lot of math in grad school. Great little tune.

2-24-10: The Oak Street Connector

I was indirectly pointed to (through Deadspin of all places) the Yale Daily News the other day, where I found an interesting article on the Oak Street Connector. The Connector, widely seen in the area as a failure that simply uprooted many neighborhoods, is a center piece of New Haven. The article goes through the controversial past and possible future of the relatively short span of abruptly ended highway that was to connect the shore with the downtown area. After the city simply ran out of money, and after a few lawsuits, the Connector barely makes it to York Street. It's as if a highway just gave up trying.





Having grown up about 30 minutes south of New Haven, I know some of its history, but whatever of it I did learn was from its early days as a colony and major port. I had no idea of the more recent history of the Connector, though I've driven on it many times. I always enjoy seeing little bits and pieces of local history. When I was first able to walk around Derby, where I now live, I made sure to stop to read the few monuments in town. Sure, every town has history, and I'm not saying any one place is truly special, but knowing the local history, for me, is more interesting than reading something about Europe or somewhere that's often experienced in a 7 day tourist trip. It's also much cheaper.

2-23-10: The Social Construct Known as "Maybe"

Will some one please explain to me what motivates potential party-goers to respond "Maybe" to an invite.

I am hosting, for the second year going, a St. Patrick's Day celebration. You're welcome to come, by the way. Starts at 8:00PM on Friday the 12th, at my place.

I sent out the invites for this celebration last Friday, and have been seeing the usual trickling in of responses. A couple of these responses are the dreaded "Maybe." This, my friends, I do not like. I don't know who invented the "Maybe" response on Google Calendar, but I hope that employee has either been fired or has moved on to better things (like Google Buzz), because I hate it. And, since I haven't gone on a good rant for a while, I'll explain to you, dear reader, why the "Maybe" response has no real use.

My concern as the host is if you, the invited, will attend my party. This should be a binary response: "Yes" or "No." When I see a "Yes" response, I think "This person is planning at least part of their day to attend my party." When I see a "No" response, I think "This person already has plans and is kind enough to take the time to let me know they are definitely not showing up." Both responses are perfectly fine, and appreciated. When I see a "Maybe" response, I think "This person is letting me know that they know I'm having the party, but that it is not one of their top priorities."

Let's go back to my role as the host: is this person attending or are they not. I really don't need to know what this person's priorities are. I want to know, one way or the other, if they're planning to show up. The "Maybe" response, to me, is NOT a "Maybe" for attendance, it's simply a "Soft No" unless it turns into a "Yes." A true "Maybe" is the simple non-response. A lot of people employ that technique, which I like less than a "Yes" or "No," but more so than a "Maybe" response. Please, if you are a legitimate "Maybe", just don't respond. That is totally understandable. I don't expect you to drop everything you're planning just to attend my party. It's not a big deal. But, whatever you do, don't respond "Maybe." It doesn't help me.

And Google Calendar employees: if there is any way to prevent possible attendees from responding "Maybe," please let me know. Thanks.

2-21-10: Carved Ski Turn Instructional Video

I've been looking for a good instructional video on how to learn to do carved "S" turns while skiing.

Here's a pretty decent one that I hope will help me learn the dynamic turn:

2-18-10: Deriving the Transfer Function for a Simple Closed-Loop System

I'm taking a course in Feedback and Control Systems as part of my graduate studies, and, while helping another student last night after class, I realized that it is indeed a very good thing to know how to derive a solution rather than to simply memorize an equation.

The question was simple: how does one derive the transfer function to a simple closed loop system?

Take the following system as an example:

The system components are the Reference input R(s), what you want the system's output to be, M(s), the Controller, G(s), the Plant or model of the system, Y(s), the output of the system, and H(s), the Sensor. In addition, I have added X(s), which is the output of the Sensor, and W(s), which is after the summing block.

Last night I "walked around the loop" with my fellow student to help him understand how to get the transfer function, which is Y(s) / R(s), or simply the ratio of the output to the reference input.

Let's start by finding W(s) and X(s) in terms of the system components.

(1) W(s) = R(s) – X(s) the output of the summing block

(2) X(s) = H(s) * Y(s) remember that Y(s) is fed back through H(s)

Now let's find Y(s) in terms of W(s):

(3) Y(s) = W(s) * M(s) * G(s)

Now insert Equation 1 to eliminate W(s) from Equation 3 above.

(4) Y(s) = [R(s) – X(s)] * M(s) * G(s)

Now insert Equation 2 to eliminate X(s)

(5) Y(s) = [R(s) – [H(s) * Y(s)] ] * M(s) * G(s)

Now we have an equation for Y(s) in terms of all the other system components. Now we just need to get Y(s) / R(s):

(6) Y(s) = R(s) * M(s) * G(s) – H(s) * Y(s) * M(s) * G(s)

(7) Y(s) + H(s) * Y(s) * M(s) * G(s) = R(s) * M(s) * G(s)

(8) Y(s) * [1 + H(s) * M(s) * G(s)] = R(s) * M(s) * G(s)

And the finale:

(9) Y(s) / R(s) = [ M(s) * G(s)] / [1 + H(s) * M(s) * G(s)]

MikroKopter - HexaKopter

Link thanks to grinding.be:

MikroKopter - HexaKopter from Holger Buss on Vimeo.

Google Tricks Out Snowmobile Cam for Stunning Slope Views

Whoa.

 

 

Sent to you by Pat via Google Reader:

 

 

Google Tricks Out Snowmobile Cam for Stunning Slope Views

via Wired Top Stories by Priya Ganapati on 2/9/10

Google's Street View team shoots the slopes of Canada's Whistler mountain using cameras with extra hard drives attached to a snowmobile and an SUV. Ski downhill on the Olympic runs for a real off-Street View.

 

 

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