Friday, July 5, 2013

Walking your way to a full battery

Chris Gammell, of Chris Gammell's Analog Life and The Amp Hourtweeted about this gizmo. Not surprisingly, it set off his bullshit sniffer, and mine too. So, let's do a tiny little bit of physics and find out if their claim to a fully charged iPhone battery in 2.5 miles is legit.

First, the assumptions:
1. My mass is 75kg. I wish, but that's close enough.
2. My stride length is about 6 feet, so 3 feet per step. A little long, but probably close enough. That gives me about 4400 steps in that 2.5 mile walk.
3. I lift my foot about 10mm with each step.
4. An iPhone battery has about 1500mAh of battery life, which, for an average LiPo battery voltage of 3.7V, translates to 5.5wh, or approximately 20kj of energy required.

For a standard gravity, 10mm step height, 75kg person, and W = f x d, we get 7.35j per step. 4400 steps gives us 32kj total generated; we need to capture 20kj of that to charge the phone. That's 62.5% of the energy generated.

That strikes me as a high, but not *totally* unattainable goal.

Call this one "I'll believe it when I see it", which is better than "flim flam and snake oil".

Saturday, March 9, 2013

In Which I Create A Kerfuffle

Caveat lector--this post has nothing to do with making anything. Except the aforementioned kerfuffle.

First things first--I am absolutely aware of my privilege. I'm a cis, hetero white man, of unexceptional girth and slightly more than average height. I have no scars, no birthmarks, no differences of ability which would draw the eye. In short, I'm playing the Game of Life on the lowest possible difficulty level, and damn lucky for it.

So. A few months ago (right before Hogswatch Christmas), I decided to start painting my fingernails. I've always wanted to--or, at least, since I was at least a preteen--but I've never had the courage to do it. I'm not prone to an action such as this simply for attention or to be "different". I simply realized that, for the first time in my life, I was comfortable enough with myself and my life to scratch a long-denied itch.

My beautiful wife bought me many varieties of polish, and I've been painting my nails ever since. A couple of people at work teased me a bit, of course, but out of love, and that's been that. Since then, I've enjoyed the meditative experience of the delicate work of applying polish to my nails, the experimentation involved in figuring out how to keep my nails looking good as long as possible, the attention I get from people about my color choices. It's been an altogether positive thing in my life.

A week ago, I shot a product video for work. I gave a nice little tour of a new circuit board, pointing out the various features with, naturally, my (beautifully blue nailed) fingers. I'll own I was curious how it would be received; I was anticipating a bit of insult slinging, along the lines of "What a fag" or "That chick's got really hairy arms". What I wasn't prepared for was anger.

There is no such thing as a grown up, there are just kids who get older and have kids of their own, and no one really knows what the hell is going on. And this guy painting his nails is a perfect example. Also, it's our right to judge people too, it's a perfectly natural thing to do, based on my observation of his nails, I can see that he is very insecure and probably makes a lot of bad choices in life, IF he actually did paint his nails for personal reasons. (Aliens8MyCows) 
NO DEAL! I tried not letting it bother me, but it REALLY DOES BOTHER ME THAT HE MADE A VIDEO WITH PAINTED NAILS. Same way it bothers me when people where pants below their butt, or how Afghan women wear those cloths around there face. Its somewhat offensive... (Marco LovesNambla)
To those who want to pretend that a man wearing nail polish is no big deal, why is his urge then so great that he wear it to work in a highly visible public setting. There is no way anyone could be so clueless as to not know how socially unaccepted that is so it has to be very intentional. Like a drama queen looking for trouble.
Stuff like that is a clear indication of mental issues. Same as guys wearing a thick black strap around the wrist.
Like Sandra Bullock should have done, just say no  (Dan Frederiksen)

I'm pretty amazed by that, truthfully.

I'm not really offended by it--if I'm not expecting blowback surrounding such a thing by the age of 34, I'd be a fool indeed--but, geez, do these people really think I didn't know that I was doing something outside the norm?

Anyway, it's been an interesting taste of what it's like to be outside of my privileged class. I can always take off the nail polish. It's not who I am, and it's not central to my sense of self or well-being. Were I, for example, transgender, I'd imagine the reaction would be much the same, and I doubt I (or anyone) could be so sanguine as I am about this.

Finally, I want to thank my coworkers for their support. The outpouring of genuine love from them only reiterates to me that, for perhaps the first time in my life, I've found a group of people that I truly fit in with. I'm proud to be a part of an organization of people who will go to the mat for something as silly as my right to wear nail polish--I can only imagine what they'd do for someone who is LGBT or of a minority suffering similar slander.

Friday, May 4, 2012

Capstone classes and "real" engineering

I'll attempt a bit of subterfuge and obfuscation here so I don't inadvertently ruffle too many feathers...

A friend just sent me a summary of the EE capstone projects from this year's crop of students at a university that shall go unnamed. Bright-eyed young engineers, fun problems, innovative solutions, yadda-yadda-yadda. Pretty much anyone reading this has a pretty good mental image of what might have been in the e-mail, and many of you LIVED it. But then, right at the end, was an incredibly troubling BTW:

PS: professor's name here told me that he does not allow Arduinos to be used on these projects, since it makes things too easy (at this level of education, they're supposed to be learning the stuff that Arduino hides from you).

Better he was there than me. I'd have lost my shit if an engineering prof said something like that to me.

I get what he's saying- that the journey is the point, not the destination- it's just that for everything else these students will ever do that is dead wrong. And I'll agree with one thing: for a microcontroller class, Arduino is the wrong choice because it does abstract away important concepts. But this isn't a microcontroller course, it's the capstone course, which is as close to an actual "design-a-solution-to-this-problem" assignment as most of these kids will get before they find their way into a workplace.

Giving these kids the (mistaken) idea that solution A (which requires 5 hours to realize because you used an Arduino) is somehow inferior to solution B (which requires three months to realize because you have to select a microcontroller, design, fab, populate, and respin a PCB, write code mostly from scratch, and do all this without a tremendous body of prior work and community support which is directly applicable to the code and hardware you're working on) is only going to cause trouble down the road- trouble for them, for the more experienced engineers they are hired to work with, and trouble for clients whose dates get missed because using solution A feels like "cheating" or "not real engineering".

I was taught that the point of an engineering education is to get a person to learn how to solve problems, not how to use tools (cross reference Isaac Asimov's wonderful short story "Profession"). The point of a capstone class, IMO, is to take the gloves off, put the students in the ring and expect them to beat the problem into submission through any means they see fit.

This idea, that the "easy" solution is wrong, undermines a core tenet of engineering- the "right" way to do something is any way that comes in fully functional, on time, under budget, and which is set up to perpetuate those three things into the future (i.e., is maintainable). I've known plenty of engineers who were so caught up in doing something the "elegant" way that they would never dream of not writing their own floating point library (in assembly!) for their microcontroller of choice even though there's a perfectly good library already written.

Done is beautiful.

Saturday, January 21, 2012

Numeracy fail

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.

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.

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)
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:
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.