Path-Optimization diagram

In case my explanation partially confused you, here is a diagram to complete the process. T means traffic.

Bow before my MS Paint skillz!

Path Optimization

When you're walking from one place to another, do you path-optimize? That is, do you try to determine the quickest way to get to your destination? i'm not talking just about crossing the parking lot instead of walking along the sidewalk around the parking lot, though that might be part of it. In my life, it's a little more pervasive. Here's an example:

On most days, i bring a lunch to work with me. It's fairly easy and definitely cheaper than going out to eat. On those days when i don't, though, i usually end up going to a block where there are a bunch of food carts (usually for Thai, but next time i'm going to try the Bosnian cart). They're all relatively cheap for a good meal. The carts are, from the door of my building, 2.5 blocks north and 2 blocks west. i'm pretty much forced to go the 0.5 block north, so i don't have to make any decisions until i have 2 blocks north and 2 blocks west. For completeness (because you must know this), i also have to cross 3 streets in each direction, all one-ways.

So when i come to an intersection, should i cross north or west? The streets running east/west (that i have to cross going north) tend to have more traffic on them and do not have stop signs, whereas those running north/south (cross west) have stop signs and less traffic. Therefore it is more likely that, coming on any given intersection, it will be easier for me to cross west than north. So, if i have the opportunity, i cross north first. Let's beat a dead horse examine a hypothetical example. <needlesslyLongExplanation skipIf="itBoresYou">i leave my building and head north to the first intersection, where i find myself at the southeast corner (needing to cross both north and west). There is no traffic coming on the east/west street, so i cross north and continue northward to the next intersection (i do not cross westward even though i could). At the next intersection, there is traffic on the e/w street so i cross west. By the time i've crossed, the traffic has lessened and i can cross north again. i do so and continue northward to the next intersection. Once there, my only crossing option is to cross north, but there is traffic, so instead i turn and walk down the block westward. At each intersection i come to, i again check the traffic and cross north if possible. Once i make that northward crossing, i am on the same side of the street as the carts, so i only need to travel west until i reach them (unless i haven't been able to cross until i am already as far west as the carts, in which case i'm already there).</needlesslyLongExplanation>

i make similar decisions when i walk home from the Max station after work, but i also have a goal, which is to get as north as soon as possible because the walk is nicer there. So i'm not completely enslaved to optimization. Good thing, too, because otherwise i would have a hard time going for walks with Michelle and Gavin ("You mean we're going for a walk to nowhere in particular and will end up right back here? But we're already here! We're done!").

i also know that, in downtown Portland, if i walk briskly against the flow of (vehicular) traffic i can hit all the walk signs. It works going north/south as well as east/west, meaning all the lights are timed approximately the same. i'm not even sure why i noticed this, but it aids significantly when i need to walk more than just a few blocks downtown (by myself - i wouldn't subject someone else to my frantic pace).

Things i (have done || do)

• Biking to work is not nerdy. Figuring out how much the wind affects you while riding is.
• Watching your child develop is not nerdy. Thinking that the second derivative of his cognitive abilities (w.r.t. time) is positive is.
• Liking math is not nerdy. Laughing at (or making) jokes about second derivatives (see above) is.
• Knowing words is not nerdy. Assigning numeric values to them (with your own private algorithm) is.
• Liking puzzles is not nerdy. Having already seen and solved all the ones in this post is.
• Watching science fiction movies is not nerdy. Discussing the geophysical impossibilities in a Vin Diesel film on the ride home from the theater is.
• Celebrating pi day is not nerdy (ok, maybe it is). Celebrating pi day at 1:59 AM is. Not having to look up what time to celebrate it definitely is.

Blog Updates

i've been doing some formatting updates and such on this blog. Really, the look of things haven't changed, but now i have more control over layout and such. It requires that i start using more tags rather than assuming that Blogger will do it, but that's really a small price to pay for the few pixels that i now control that i didn't before.

Biking in the wind, part 2

So, i worked out the whole biking in the wind thing to include the fact that i'm moving as well and came up with some new numbers. These are a little better (for my ego) than the previous ones. i assumed that i was traveling 10 mph, which seems reasonable. i won't bore you with the new equations. Here are the results:

• θ = 0º, V = 0 m/s
• θ = 5º, V = 8.9 m/s (20 mph)
• θ = 10º, V = 14.0 m/s (31 mph)
• θ = 20º, V = 21.1 m/s (47 mph)

i will not vouch for the accuracy of these numbers. i haven't done any physics in a long time.

Baby Gifts

We were recently pointed to these by Amy, and it got me wondering... What is the nerdiest gift you can give to a baby/young child? Also, will you confess to actually owning any of them?

Biking in the wind

Since i've been biking to work a lot, i've noticed that biking into the wind seems to be just as hard as biking up a hill. Often times, i'll wonder why it seems like my legs just don't have the power they should, and then i'll look around and see that the trees are swaying. Sometimes, i look up and there's no wind, and that is somewhat disheartening. Overall, though, i can definitely feel the effects of the wind.

So how strong of a wind equates to what grade of a hill? Seeing as how i've taken a couple of physics courses, i'm going to try to figure it out myself. Let's see (feel free to close your browser now)...

First, the hill - let's determine the extra energy i get when powering (or puttering) up a hill.

If my mass is m and i'm going up the hill at an angle θ and velocity v, then the height increase in time t is:

h = v*t*sin(θ)

Now, the potential energy equation is PE = m*g*h. g is the gravitational acceleration = 9.8 m/s^2. So the additional energy i've gained is:

E = m*g*v*t*sin(θ) = 9.8*m*v*t*sin(θ) (m/s^2)

So, let's leave that for now. Now we need to determine the energy lost from wind resistance. The drag equation is:

D = (1/2)*ρ*(V^2)*A*Cd

• ρ is the density of air ≈ 1.2 kg/m^3
• V is the wind velocity
• A is the cross-sectional area of me and my bike. i'm going to say that my bike and i present a 1m by 1m cross section (i'm short, but really wide), so A = 1 m^2
• Cd is the drag coefficient, which is apparently 0.9 for a bicyclist

So that's a force, but we need energy, so i'm going to use E = F*d, and d = v*t, so we get:

WE = 0.5*1.2*(V^2)*1*0.9*v*t = 0.54*(V^2)*v*t (kg/m)

Equating the two equations, we get:

0.54*V^2*v*t (kg/m) = 9.8*m*v*t*sin(θ) (m/s^2)
V^2 = 18.1*m*sin(θ) (m^2/kg*s^2)
V = √(18.1*m*sin(θ))

The final equation units comes out to m/s, which is good. At least the units are right. Let's try some actual numbers in there to see what kind of results we get.

Since i'm already a massive square, let's also assume i'm 100 kg, for ease of use.

V = √(1810*sin(θ))

For different values of θ:

• θ = 0º, V = 0 m/s
• θ = 5º, V = 12.6 m/s (28 mph)
• θ = 10º, V = 17.7 m/s (40 mph)
• θ = 20º, V = 24.9 m/s (56 mph)

That seems a bit extreme. Really, though, the V should include my velocity on my bike, and should be balanced out by my riding through no wind on the other side (there will still be drag). So maybe it would kind of work out closer to what i think should be the case. But i'm too lazy to work all that out right now. And i need to go do some other things. So maybe next time.

The other explanation is that i'm just a wimp (oh no, wind!). That's definitely possible.

xkcd

As i've mentioned, i like xkcd. You, too, might like it if you like:

• the scientific process
• physics
• math
• statistics
• prime numbers
• orders of magnitude
• computer programming
• randomness
• resistors
• Star Wars
• James Bond
• the NES
• researching before you buy
• flowcharts
• Garrett
• puzzles
• ocd
• cats, both alive and dead (language)
• uncomfortable situations (or me)

If you like all the above (and understand the comics)? Well, i just hope you're married to a Techer. Or someone else equally as nerdy.

Believe it or not, i did narrow down the list from what it was originally. i removed a couple that were even nerdier than the ones listed. i'm pleased that there are now a prime number of list items.

Et Cetera

Michelle wants you all to be aware of Alley Assassin from 2002. Her alley, swamp, consisted of all girls and absolutely dominated, and she herself registered 2.0 kills, under the pseudonym Michelle Swann. She said she didn't want to become a master assassin because then she'd have to be paranoid about being a target, but the site lists her as a target already, so i'm not sure what's up with that. It turns out that my co-workers should really be afraid of her, not me. But i'll let them believe whatever they want as long as it keeps me safe. Besides, i may just call on her to give me some help.

i was recently pointed to this excellent song (thank you Dan). Created by a professor at Caltech, David Politzer (Nobel prize in Physics, 2004), it is a song that, if i may say so, resonates deeply with my nerdy core. If it doesn't make much sense to you, you can be thankful that you aren't a complete nerd. If you find it hilarious, well, there's not much i can do for you. Except join you.

Happy third luniversary to my son, Gavin! At three months old, he continues to amaze me, and i love him more all the time.

Pranks

i work in IT, and since our group is fairly typical, there tend to be a fair number of pranks that happen. Or, at least, a fair number of pranks that get talked about. To be fair, there are a few pranks that are pulled off, but most of them are so lame that they aren't even fair pranks. Most of the ideas revolve around waiting until someone leaves their laptop alone without locking it, and then sending an email to their boss (or their boss' boss) telling them how much they are loved. Or installing some program that changes their desktop background every 30 seconds. Or setting their screen saver to come up after 2 seconds of inactivity. The last two haven't even happened, that i'm aware of, just been talked about. Oh, there's also the class of 'disconnect some wire so the person can't use their mouse/talk on their phone. Really, i would call most of what goes on around here hijinks, not pranks.

Our boss (let's call him B) actually comes up with, and pulls off, the best pranks. i have a fairly gullible coworker (let's call him G) who is most often the victim of these pranks. Once, for example, G was about to go on vacation to Vegas for a week. At some point during his last day before the vacation he got pretty frustrated with something and swore loudly. Across the cubicle divider from him is someone who didn't appreciate that. G realized that. Soon after the incident, he left for Vegas. When he got to Vegas, he had a voicemail from B saying that a complaint had been filed with HR and he needed to call B about it soon. He freaked out (thought he was going to lose his job) and called B, who directed him to another manager (M) because "i don't think i can be objective in this." So G called M, who was also in on the prank, and M led him about for a little before breaking the news to him. Thankfully, G is good-natured about it all.

So there have been a few good pranks, but so far no one (including me) has really stepped it up besides B. i'm not that much of a prankster, though if i'm going to pull a prank, i do have my standards. My main goal is to prevent people from pranking me. So far, it seems to be working. The others on my team seem to think that any prank they pull on me will be revisited on them in mutated and larger form. i think they're intimidated by stories about pranks from Caltech and assume that i am heir to that legacy.

And they don't even know about Alley Assassin.

Things My Wife and i do For Fun

(slightly paraphrased)

Michelle: i talked with Anna today. i also left messages for Colleen and Anya. i didn't get around to calling Beka or Amy, though.

Me: Wow, that's a lot of names at the beginning of the alphabet. 3 A's!

Michelle: And they're all two syllables. And four of the five have the accent on the first syllable.

Me: Not to mention that three end with the short a sound.

Michelle: One's a palindrome too.

Ah, set decomposition.

High-School Dreaming

Last night i dreamt that i had to go back to high school. Strangely, i was excited about this fact. It turned out (in my dream) that students have 5 years of eligibility to play basketball, so i was going to be able to play for a year. Also, Shaq and Dwyane Wade were both going back to high school with me (yes, the one from which i graduated with 9 other people). We were totally going to win state.

i was originally pretty bummed that i'd have to take high-school classes again (i've already taken them, and some were pretty boring the first time through), but then i realized that i could take calculus as a freshman and then move on to higher level math classes in future years. That made me much more eager to start back in. Thinking back, i'm not sure why i stopped at calculus. i could have started at least with something i don't know as well and that i might find more interesting, like linear algebra. Dreams can be so illogical.

i'm not sure why i'd have a dream like that, but there are some points that i can pick out origins for. The 5 years of eligibility, for example, is actually from college. You can only play in 4 of those 5 (contiguous) years, but if i had returned to Caltech for grad school or some such, i could have still played. But i haven't thought about that in a while. i also have no idea why i picked Shaq and Wade to come back with me. i hope it isn't post-dream imprinting because i read an article about them today, but i suppose it could be. Regardless, it was definitely two professional basketball players.

i've also been thinking lately about keeping my brain active - trying to continue to learn different things so i don't get stuck in a rut and let life pass me by. i've been working on my photography skills, and try to learn new things at work (programming languages/paradigms, best practices...). So maybe that's where that piece comes from.

So that might explain where the different pieces came from for the dream, but why did they all come together on one night? Who knows, but it was fun dissecting things. Thanks for your patience.

Reason ξ i Miss Techers

i was in a meeting today, and one of the other members of our team was talking about interface standards. She mentioned that she was going to meet with another group to try to come up with some common standards - a unified template if you will (yes, she used those words). i immediately thought "Really, a Grand Unified Template? Like that's going to happen anytime soon."