Side note- it's been a looong time since I wrote a blog post. Since then, I've had a second child, moved jobs (I'm now working at SparkFun- woot!), states (Colorado is state number six for me), and time zones. A lot of the more technical sort of blog post I'd write now goes up on the SparkFun website as tutorials, but I'm going to try to post more here.
Engineers and scientists (and other general nerd/geek types) like to talk about "numeracy", which is the ability of a person to grok math. It used to be that the primary "complaint" (if you will) was about people who play the lottery- "a tax on being bad at math". I'm not talking about valuation, here- being willing to pay five- to tenfold as much for a meal at a restaurant as it would cost to make at home, for instance. I'm talking about hard numbers- apples to apples.
Having a poor grasp on mathematics is getting to be a bigger handicap, though. I've notice recently when grocery shopping that the old principle of "buy more, save more" no longer applies- frequently, a bigger box of cereal, say, will cost MORE per ounce than a smaller box.
Or, containers will be cleverly redesigned to contain less but look the same, then the price is maintained. Next time you're at the store, check out the "half gallon" containers of orange juice. Many (most?) of them are 59 ounces, instead of 64. They don't look any different, of course, and there's no mention on them that 59 ounces is NOT a half gallon (and I'm not optimistic that many consumers know what a half gallon is, nor would be able to calculate price per ounce between a 59 ounce jug and a 64 ounce jug).
I noticed this BECAUSE I grok math. I do simple mental arithmetic many, many times a day as an electrical engineer- calculating expected currents, expected power consumption, approximate required resistance, etc etc. When I look at a package in the store, I can't help but calculate a price-per-ounce of the contents. It's usually right to within 5 percent or so- I round to make the math easier (metric would make it easier yet- is that why we haven't changed?). But I was noticing that there were discrepancies that could not be papered over by hurried mental math.
Keep an eye open- I've heard from a few others that they've noticed this but I'm curious how widespread this practice is.
One other place I've noticed crap numeracy is in science writing, and this is REALLY disturbing to me. Two variations on the same metric will be given in a book or article- say, the number of children who die of malaria every day and the number of people who die of malaria in a year. These values may be reported multiple times and usually won't be reported in close conjunction with one another (note that I don't think this is an attempt at dissembling by the author- it simply reflects the where and when in the work that each makes sense to be mentioned). The troubling thing is, the numbers reported are frequently mutually exclusive. For the above example, the number of deaths per year due to malaria may be reported as, say, 500,000. Quick mental math says that this implies slightly more than 1,000 people per day (remember, I'm an engineer- pi is "about 3" until I need a better answer). Elsewhere, a value of deaths of children will be given, and that number will be, say, 1,500 per day.
In my mind, alarm bells go off. I didn't calculate exactly how many people per day are claimed to be dying of malaria, nor exactly how many children per year are claimed to be dying, BUT my order-of-magnitude estimate tells me that the author is either not counting children as people or not paying attention to math. Frighteningly enough, neither was the editor nor anyone else who weighed in on the book. This kind of basic mathematical error casts doubts on everything else in the book- after all, someone who isn't capable of that kind of mental comparison is certainly unlikely to be able to judge the veracity of more complicated mathematics behind statistical predictions and observations that form the basis of most proposed solutions.
I'm not sure there's much we can do about this- I grok math because it's very much part of my daily life. I exercise those mental muscles constantly to a point where I apply them unconsciously to situations most people don't even relate to math. Maybe some kind of wide-scale gamification of mathematics? At any rate, I don't think it's something that can be addressed by education. Mathematics is fundamentally a foreign language to the human brain, and the only way to really learn a foreign language is to use it, over and over, until you are fluent.
Saturday, January 21, 2012
Friday, July 1, 2011
Fun Google maps satellite image find
I found this image on Google maps satellite images the other day.
It's a E-3 Sentry taking off from Tinker AFB near Oklahoma City. At first I thought it was a KC-135 (and that's what it went out on Twitter as) but then I noticed the rotodome on top.
It's neat because you can see the sequence of images as captured by the satellite. In the first "frame", it's just starting to pull away from the ground, and by the last frame it's well off the surface and past the end of the runway. You can also see the procession of the rotodome- the band of gray in the disk shows the rotation.
It's a E-3 Sentry taking off from Tinker AFB near Oklahoma City. At first I thought it was a KC-135 (and that's what it went out on Twitter as) but then I noticed the rotodome on top.
It's neat because you can see the sequence of images as captured by the satellite. In the first "frame", it's just starting to pull away from the ground, and by the last frame it's well off the surface and past the end of the runway. You can also see the procession of the rotodome- the band of gray in the disk shows the rotation.
Tuesday, June 21, 2011
What is the propagation speed of a yawn?
On the bus the other day, as I was rolling past waiting commuters on Marquette Ave in downtown Minneapolis, I saw a yawn traveling along through the crowd. Or at least, that was the appearance- it may have just been that people were randomly yawning as I passed. Regardless, that got me thinking: what is the propagation speed of a yawn through a given crowd?
We should be able to express that as an equation, if we choose our parameters wisely. First, let's define "speed", for the purposes of this exercise, as the time required for a yawn to travel a given distance through a crowd in any direction. The reason for that wording will become clear later.
So, that brings us to the equation:
V = d * q * (m / r) * f(C)
where
d is the average delay between when a person sees a yawn start and starts yawning themselves
m is some distance factor (it can be observed that someone closer is more likely to inspire a yawn than someone farther away- m will have to be determine experimentally)
r is the average distance between crowd members
f(C) is a function of the crowd shape, orientation of individual members to each other and crowd activity
f(C) can be thought of as a "crowd quality" metric, and it will be different for linear crowds (people waiting for the bus, but all facing the sreet), crowds where there is no orienting factor (people waiting for a concert, for instance, who may be facing any direction based on where their friends are), queues, or spectating crowds. It is also likely that by being similarly primed mentally will factor into f(C)- a room full of bored college students is more likely to propagate a yawn quickly than people waiting for a bus, all with different degrees of boredom and internal mental activity.
Now, let's consider directionality. If we pick two arbitrary points and attempt to measure the propagation time between them, we will get a false sense of the travel time because of the meandering of the yawn through the crowd. It is thus better to simply pick a "patient zero" and then watch for a yawn to occur in any person at a given radius away from that person. The resulting scalar value is the speed of a yawn, or perhaps the "speed of lassitude".
We should be able to express that as an equation, if we choose our parameters wisely. First, let's define "speed", for the purposes of this exercise, as the time required for a yawn to travel a given distance through a crowd in any direction. The reason for that wording will become clear later.
So, that brings us to the equation:
V = d * q * (m / r) * f(C)
where
d is the average delay between when a person sees a yawn start and starts yawning themselves
m is some distance factor (it can be observed that someone closer is more likely to inspire a yawn than someone farther away- m will have to be determine experimentally)
r is the average distance between crowd members
f(C) is a function of the crowd shape, orientation of individual members to each other and crowd activity
f(C) can be thought of as a "crowd quality" metric, and it will be different for linear crowds (people waiting for the bus, but all facing the sreet), crowds where there is no orienting factor (people waiting for a concert, for instance, who may be facing any direction based on where their friends are), queues, or spectating crowds. It is also likely that by being similarly primed mentally will factor into f(C)- a room full of bored college students is more likely to propagate a yawn quickly than people waiting for a bus, all with different degrees of boredom and internal mental activity.
Now, let's consider directionality. If we pick two arbitrary points and attempt to measure the propagation time between them, we will get a false sense of the travel time because of the meandering of the yawn through the crowd. It is thus better to simply pick a "patient zero" and then watch for a yawn to occur in any person at a given radius away from that person. The resulting scalar value is the speed of a yawn, or perhaps the "speed of lassitude".
Wednesday, June 1, 2011
Why Dunbar's number matters
So, I cast a fairly wide net in terms of things I passively track for potential food-for-thought. Blogs and tweeps, books, articles, etc- I try not to limit myself too much because I can skim pretty quickly across a fairly vast swath of content, even if it IS just a drop in the bucket.
This morning, the following tweet came through, from Tim Hurson:
I think there's a little more to that tweet than the 140 character limit allows. See, to people who consider you to be inside their monkeysphere, you are a collection of behaviors, and they have collected a series of behaviors to build a heuristic representing you and your expected reaction to future stresses.
To people who do NOT consider you to be inside of their monkeysphere, you are nothing more nor less than what you are doing at the moment. If you cut them off in traffic, you're a jerk. If you hold the door open, you're a nice guy.
The tricky part is, we all have people in our lives (co-workers, fellow bus commuters, hackerspace members) who consider us to be inside their monkeysphere, but we consider to be outside of our own, and vice-versa. This can cause major friction when someone behaves in an unacceptably familiar manner.
I guess my point is, the next time somebody irritates you or angers you, consider the Venn diagram of your respective monkeyspheres. If there is no overlap at all, there's a very good chance that the conflict is highly situational and not due to some intrinsic defect in either of your personalities. If there's a possibility of asymmetrical monkeysphere inclusion, ask yourself if you would change your judgment of their actions if you were closer to them, or if their actions would make sense if they were closer to you (or if they think they are closer to you than you think they are). And if you are within each other's monkeyspheres, then it's probably worth it to deal with the conflict as well as you can before it becomes a major problem.
This morning, the following tweet came through, from Tim Hurson:
To ourselves we are a complex of thoughts and feelings. To others we're just a bunch of behaviors.Really not engineering related, of course, but it meshed well with something else I saw come through my twitter stream- a post about Dunbar's number, which is the supposedly optimal group size of human culture: the number of people that you can conceivably know about and care about. That group of about 150 individuals is your monkeysphere, and people outside of it are, to some extent, not really people in your mind.
I think there's a little more to that tweet than the 140 character limit allows. See, to people who consider you to be inside their monkeysphere, you are a collection of behaviors, and they have collected a series of behaviors to build a heuristic representing you and your expected reaction to future stresses.
To people who do NOT consider you to be inside of their monkeysphere, you are nothing more nor less than what you are doing at the moment. If you cut them off in traffic, you're a jerk. If you hold the door open, you're a nice guy.
The tricky part is, we all have people in our lives (co-workers, fellow bus commuters, hackerspace members) who consider us to be inside their monkeysphere, but we consider to be outside of our own, and vice-versa. This can cause major friction when someone behaves in an unacceptably familiar manner.
I guess my point is, the next time somebody irritates you or angers you, consider the Venn diagram of your respective monkeyspheres. If there is no overlap at all, there's a very good chance that the conflict is highly situational and not due to some intrinsic defect in either of your personalities. If there's a possibility of asymmetrical monkeysphere inclusion, ask yourself if you would change your judgment of their actions if you were closer to them, or if their actions would make sense if they were closer to you (or if they think they are closer to you than you think they are). And if you are within each other's monkeyspheres, then it's probably worth it to deal with the conflict as well as you can before it becomes a major problem.
Thursday, May 26, 2011
UptownMaker goes to the Faire
This past weekend I attended Maker Faire in San Mateo. It was an absolute gas (does anybody use that phrase anymore?)! I'm going to do a few quick posts highlighting my favorite sights- all my pictures and videos are on my Picasa site.
I'll start out with my favorite first: Miss Haley Who, swamp kirin wrangler.
This lovely fellow is a mechanical swamp kirin. He stands about nine feet tall and though he looks ferocious he's really quite gentle.
Haley Who, aka halo seabat, built this majestic creature as a gift for her little brother, Seth. It seems Seth was a bit heartbroken after their father explained that the few remaining wild swamp kirins in the east were best left unmolested in their natural habitats, and halo took pity on her brother, building him this mechanical version.
The pair of them wandered about the grounds, charming the pants off of just about everybody they met. Haley's disarming smile, the kirin's gentle gait and their tender interplay softened the overall image to the point where I never saw even the smallest of children exhibit any fear at all- mostly they wanted to touch the kirin, stroke its legs, even kiss it on the nose.
It felt magical, and I'm a happier person for knowing Haley and her kirin friend are out in the world.
I'll start out with my favorite first: Miss Haley Who, swamp kirin wrangler.
This lovely fellow is a mechanical swamp kirin. He stands about nine feet tall and though he looks ferocious he's really quite gentle.
Haley Who, aka halo seabat, built this majestic creature as a gift for her little brother, Seth. It seems Seth was a bit heartbroken after their father explained that the few remaining wild swamp kirins in the east were best left unmolested in their natural habitats, and halo took pity on her brother, building him this mechanical version.
The pair of them wandered about the grounds, charming the pants off of just about everybody they met. Haley's disarming smile, the kirin's gentle gait and their tender interplay softened the overall image to the point where I never saw even the smallest of children exhibit any fear at all- mostly they wanted to touch the kirin, stroke its legs, even kiss it on the nose.
It felt magical, and I'm a happier person for knowing Haley and her kirin friend are out in the world.
Tuesday, May 24, 2011
USB CDC toy
This was originally going to be my calling card for Maker Faire. It's a very simple implementation of Osamu Tamura's AVR-CDC project, realized without a board. I had planned to make it a small device that can be plugged into a USB port and observed on a terminal spitting out information about me. The Great Global Hackerspace Challenge project took a lot out of me, though, so I didn't get it done in time.
The blobby on the left is an I/O module- three input switches, three output LEDs, and a reset switch and power LED. It plugs onto the header that is currently being used for programming. The circuitry is pretty simple: 100nF bypass capacitor, the 5V in from the USB port goes to the positive supply pin through a 1N4001, and the USB D+/D- are connected to a couple of the I/O pins.
Some words about that 1N4001: it was chosen specifically for its high forward voltage. See, the USB input wants a 3.6V input or so, and the AVR doesn't want to run at the 16+MHz needed for this project below about 4V. Originally, following the schematic on the project home page, I was using a red LED as a voltage drop. The AVR never ran stably- the voltage (about 3.3V) was just too low. Now, it's running at about 4.2V, and the 68-ohm resistors between the AVR and the USB limit the current to just a few mA, and everybody's happy.
Right now, I'm up to my elbows in the source code of the original project, removing the serial I/O code and replacing it with easily used hooks for internal functions. Ultimately I'll bend it to be programmable through the Arduino interface- for now I'm working in AVRStudio5. Once I have it all done I'll release all the deets so anybody can make one. I may also make a PCB and sell kits for it through NoCube, and probably just the pre-programmed IC, as well.
Inductive power
About two years ago I decided I was going to figure out a cheesy inductive power coupling circuit. I sat down one Sunday, started plugging some stuff together and this is what I ended up with:
This is the circuit I brought with me to the "bring-a-hack" dinner at Harry's Hofbrau that Jeri Ellsworth organized on Sunday night. You can see that the LED in the jar is lit- the jar is really just a gimmick and the little parasite works better outside the jar.
The circuit is very simple: the IC in the middle is a 12F683 that I programmed up to be a square wave generator (someday I'll blog that project, but for now, I'll just say that the oscillator frequency is jumper selectable and it can be set to either update constantly when powered or set and forget the output frequency and duty cycle) running at 50% duty cycle and (approximately) 71kHz. The square on the right is a bit of ~28ga magnet wire wrapped a few times around four screws. Power is delivered to it by a transistor- the coil gets driven by the full umph of the 9V while the PIC runs on the 5V regulator to the left.
Efficiency is TERRIBLE. Because I'm driving the transistor hard with a square wave I lose energy into the higher-order harmonics, and then I'm half-wave rectifying the output with the LED. If I made the drive waveform more sine-like and added some joule-thief circuitry to the parasite I'd see much better results. But then, this was never intended to be a huge project, just proof-of-concept.
One last thing, if you're thinking of doing this yourself: every hand-wound parasite is going to have a slightly different optimal frequency. The circuit as I made it was basically an LED, a 100nF capacitor and a coil all in parallel. Depending on the resonant frequency of the LC circuit, you'll see better results at different frequencies.
This is the circuit I brought with me to the "bring-a-hack" dinner at Harry's Hofbrau that Jeri Ellsworth organized on Sunday night. You can see that the LED in the jar is lit- the jar is really just a gimmick and the little parasite works better outside the jar.
The circuit is very simple: the IC in the middle is a 12F683 that I programmed up to be a square wave generator (someday I'll blog that project, but for now, I'll just say that the oscillator frequency is jumper selectable and it can be set to either update constantly when powered or set and forget the output frequency and duty cycle) running at 50% duty cycle and (approximately) 71kHz. The square on the right is a bit of ~28ga magnet wire wrapped a few times around four screws. Power is delivered to it by a transistor- the coil gets driven by the full umph of the 9V while the PIC runs on the 5V regulator to the left.
Efficiency is TERRIBLE. Because I'm driving the transistor hard with a square wave I lose energy into the higher-order harmonics, and then I'm half-wave rectifying the output with the LED. If I made the drive waveform more sine-like and added some joule-thief circuitry to the parasite I'd see much better results. But then, this was never intended to be a huge project, just proof-of-concept.
One last thing, if you're thinking of doing this yourself: every hand-wound parasite is going to have a slightly different optimal frequency. The circuit as I made it was basically an LED, a 100nF capacitor and a coil all in parallel. Depending on the resonant frequency of the LC circuit, you'll see better results at different frequencies.
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