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2015 January 17

Bridge Design Contest 2015

Filed under: Uncategorized — gasstationwithoutpumps @ 12:07
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It looks like I won’t be playing with the bridge-design contest software this year.  I downloaded the software from, but was unable to run it.  They’ve made their software so that it only runs on Mac OS 10.7.3 or newer, but my MacBook Pro is running OS 10.6.8.  I suspect that there are a lot of schools out there running old Mac software also, so making the software run only on the new Macs is cutting out a lot of users (particularly in the less-wealthy school districts).  This is a common problem with software developers—because they invest in the latest hardware and software, they assume that everyone else is able and willing to do so.  More likely, they don’t even think about the number of people they cut out by writing programs that only run on recent computers, nor who those people are.

Note: there is a newer iMac in the household, and now that my son is in college I can get time on it, so I might install the bridge-design software there.

I know that I could also upgrade my 10.6.8 Mac (possibly even for free still), but I’ve heard from a number of students who did the upgrade last year or the year before, that the resulting laptop was far less reliable and much of their older software was broken by the “upgrade”.  I’m not willing to have to replace large swaths of my functioning software just to play one game. I’ll put up with the pain of major changes to the operating system the next time I replace the hardware.

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2014 November 16

Good enough for what?

Filed under: Uncategorized — gasstationwithoutpumps @ 11:05
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A blog post by Nick Falkner, Thoughts on the colonising effect of education, ended with the

I had a discussion once with a remote colleague who said that he was worried the graduates of his own institution weren’t his first choice to supervise for PhDs as they weren’t good enough. I wonder whose fault he thought that was?

Nick’s implied message was that it was the duty of the professors to make the undergrads they taught be good enough to go on for PhDs.  But I’m not sure he’s right here.

We do not need huge numbers of new PhDs—some, but not nearly as many as are being graduated from BS programs. Only about 10% of undergrads (or less) should be going on for PhDs, so the majority of graduates from any institution should not be “first choice to supervise for PhDs”. We should be bringing up as PhDs those most likely to be productive researchers and university faculty, and encouraging other students to find productive lives outside of academia (there is a world outside academia, though many professors prefer to ignore it).

If most of the undergrads graduating are top candidates for PhD programs, then perhaps the criteria for PhD candidates are wrong—or the undergraduate program is too small and selective, so that students who would benefit from it are being excluded.

I’m an engineering professor, and in most engineering fields the working degrees are the BS and the MS—the PhD is reserved for cutting-edge research that is not expected to result in products any time soon and for university teaching. I would consider myself a failure as an engineering professor if none of my students went on to become working engineers, but all went into academia.

I expect many of the best students not to be well-suited for PhD degrees—they want to go out into the real world and solve real problems (sometimes to make money, sometimes to save the world, sometimes just for the joy of solving problems).  The best PhD candidates are often not the best engineering students, because a PhD candidate has to be willing to work on an esoteric problem for a really long time with no promise of success, while good engineering often calls for quick prototyping and rapid development, dropping unproductive projects quickly, before they cost too much—not long-term projects that may never pay off.

So, while I certainly want some of my undergrad students to go into academia and to be top choices for PhD programs, I’m happy if most of them are not suited for PhDs, as long as they have acquired an engineer’s problem-solving mindset, enough skills to get them started in a job, and a lifelong habit of picking up new knowledge and skills.

2014 January 18

Engineering Encounters Bridge Design Contest 2014

Filed under: Uncategorized — gasstationwithoutpumps @ 23:23
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Last year’s bridge design did not work well for the 2014 Engineering Encounters Bridge Design Contest (formerly the West Point Bridge Design Contest):

Bridge design costing about $169.9k in the 2013 contest.  Note: I've deliberately distorted the picture to make it difficult to blindly copy the design, as I had problems with middle-school students using my published designs to cheat on their homework.  The truss design I have here can be used as inspiration, but not copied directly.

Bridge design costing about $169.9k in the 2013 contest.

When I tried a similar design in the West Point Bridge Designer 2014, I couldn’t get the cost below about $172k, but a simpler design was cheaper:

$167.3k bridge design for West Point Bridge Designer 2014.

$167.3k bridge design for West Point Bridge Designer 2014.

This design is currently 12 of 41 in the open contest, so clearly one can do better. I don’t expect it to stay high on the leaderboard for long.  It would already be much worse than that on the consolidated board, since the top 10 on the open board only fall in the top 50 on the consolidated one.

I think that the contest would be more interesting to me if they had provided an API for testing bridges.  Then the challenge would be to write bridge optimization software that explored the design space much more thoroughly and tweaked the designs.  It might be possible to do that this year, as the source code is available from sourceforge.  I’m not interested enough in the optimization problem to try to interface to their Java code, but it might be a good way to make a college-level version of the Bridge Designer Contest.

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2013 September 3

My son’s first PC board

In Towards automatic measurement of conductivity of saline solution, I complained about not being able to use the KL25Z board, because my son was using it.  What he was doing with was building his first prototype for the light gloves project:

Here is his first PC board design, populated and mounted on the Freedom KL25Z board.  The 5cmx5cm board is a bit smaller than the KL25Z board is wide, so it only plugs in on one side (there is a screw acting as a spacer to keep it from being a cantilever).    He has not yet mounted the Bluetooth module.

Here is his first PC board design, populated and mounted on the Freedom KL25Z board. The 5cm×5cm board (the cheap size from Iteadstudio) is a bit smaller than the KL25Z board is wide, so it only plugs in on one side (there is a screw acting as a spacer to keep it from being a cantilever). He has not yet mounted the Bluetooth module.

The prototype board has many differences from the final design: no battery, no battery charger, no buck/boost regulator, no flash memory, no processor, screw terminals instead of jacks—even the LED driver chip is different, since the chip he plans to use is only available as a surface-mount device. But there is enough of the design here to start demoing and writing code.  They are hoping to keep the final board below 5cm×5cm, so as to get low PC board prices even in very small production runs.  That will mean all surface-mount parts, so I think I’ll have to get a hot-air rework tool so that they can assemble a prototype—I’ve been thinking that I might want one for myself to play with surface mount designs, so this isn’t really a hardship.

My son still owes me some money for buying him the PC board run, the screw terminals, the Bluetooth module and some heat-shrink tubing. It is a bit annoying that he isn’t old enough to get his own Visa card, so that he can do his shopping without me as an intermediary. (We’re not talking big bucks here—we’ve spent more on pizza for him when they work through dinner than they’ve spent on all parts combined.)

I’m pleased that he got his first PC board working on the first attempt—he did the design entirely on his own, though he did ask my advice about things like via sizes and how fat to make the wires. Since there can be moderately high currents for the LED driver, I recommended that he make the ground and power lines as fat as he could, and he decided to do a flood for each. The board looks quite nice:

The top view of the board with the screw terminal to be mounted on the top and sides, the header on the lower left, and the Bluetooth module on lower right.  The hole near the top right is for the screw that acts as a spacer.

The top view of the board with the screw terminal to be mounted on the top and sides, the header on the lower left, and the Bluetooth module on lower right. The hole near the top right is for the screw that acts as a spacer.


This is what the glove looks like with the five RGB LEDs lit up (I understand that the final design will have more LEDs—but the through-hole driver chip has limited pinout). They don’t have the user interface written yet, so the lights were set up by a quick-and-dirty Python script talking to the KL25Z board over a USB cable (which is also supplying power).


They have not implemented programmable flashing yet, but the pulse-width modulation (PWM) frequency is set very low here (much lower than what they intend to use in the final design), so that one gets a stroboscopic effect even with steady light settings, just from the PWM. That’s not my son in the picture, but the high-school student who started the project—my son has done most of the electronics and programming, but did not originate the idea.

The two teens spent a big chunk of the day wiring up the LEDs and writing a small test program, as they want to demo the glove tomorrow for the back-to-school event. It may also be an enticement for teens to join an Arduino/microcontroller club—look at the cool stuff you can learn to make!


Another view of the prototype light glove in action.

Once they got the demo working, they invited over a third member of the team to do some brainstorming about what else needs to be done (and how they’ll do it). It looks like they’ll be talking half the night.

Since it is clear that my son will be spending a lot of time on this engineering project this year, we decided to make it part of his official school work.  In addition to the engineering design work, he’ll also do some a paper for his econ course (on pricing the components and manufacturing, and setting a retail price for the gloves), and papers for a tech writing course.

His first tech writing assignment is to write up a description of the color space he decided to use for representation of colors in the program, and why he chose that color space out of the dozens available.  He spent a week thinking about color spaces anyway, before settling on a commonly chosen one—so writing up that reasoning for the other members of his team will be a good writing exercise.

2013 February 10

National Engineers’ Week

Filed under: Uncategorized — gasstationwithoutpumps @ 10:18
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Next week, 2013 Feb 17–23, is National Engineers’ Week.  (My apologies to the organizers, but I refuse to spell it without an apostrophe as they do.)

Thursday (2013 Feb 21) is Introduce a Girl to Engineering Day.

I’m not aware of anything that the Jack Baskin School of Engineering at UCSC is doing, but I’m just a faculty member, and we’re always the last to be told anything (and then generally in the form of “the deadline is tomorrow, drop everything and do it now!”). National Engineers’ Week seems to be organized mainly by international tech companies (heavy on the energy and transportation industries), and they’ve apparently not done much for involving universities in the program.

I don’t have anything planned for National Engineers’ Week myself, because I only found out about it a few minutes ago.

To be fair, I heard of it two years ago also and had similar grumbles about the lack of visibility.

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