The Systems Administrator is responsible for overseeing the planning, coordinating, integrating, and monitoring all technical aspects for the graduate Interaction Design department and digital making aspects of the Visible Futures Lab.
The experiment, which spanned more than a decade, suggests that the electron differs from being perfectly round by less than 0.000000000000000000000000001 cm. This means that if the electron were magnified to the size of the solar system, it would still appear spherical to within the width of a human hair.
Zencart Zensday! – Making an Admin Helper File – Our zen-cart mods/hacks/tips & tricks… we’ve got tariffs on each product and that’s great, but maybe we have lots and lots of products and adding tariff data to each one individually through zen cart’s clunky product interface isn’t feasible. If this is the case, we’ll need a custom Tariff info Editing file, and while we’re at it lets put it in the dropdown menu under “Catalog”.
I mentioned LiveGraph in the post about my Arduino I2C sniffer sketch, but I wanted to go into a bit more detail about it, because it’s also really handy for visualizing data recorded with the Datalogger Shield. LiveGraph is nice because it’s easy to install, easy to use, and it’s written in Java, so it’s cross-platform. Another nice feature is the native support of CSV files, and the ability to quickly export the graph as an image file.
That said, there are a few things you should keep in mind when using it, which will make your life easier:
When you are creating the format for your CSV file, put the time axis as the first entry, and make it a single value field, such as minutes or seconds (LG cannot parse a colon-delimited “time” format, i.e. 12:34:56).
By default, LiveGraph uses samples as it’s x-axis, and plots the first field in the CSV as regular data. This means when you first load the CSV file, you’ll see a straight diagonal line on your graph which may dominate the plot. You can turn this off by clicking the appropriate checkbox in the “data series settings” window.
You can tell LG to use time (the first field in the CSV) as the x-axis by choosing “data series” at the bottom of the “graph settings” window. This is exceedingly helpful if you are not logging data at regular intervals, but rather whenever some event occurs.
If you want to export your plot as an image, you can do that through the “LiveGraph” window in the “plot” menu. Something to remember though: even though you’ve chosen the image file type (jpg, png, etc.) you still have to manually add the extension to the file name (“myplot.png”).
You can download the software and check out the manual here. LiveGraph is released under the BSD license and you can check out the source code at sourceforge. Happy plotting!
*In case you are wondering, the plot above represents barometric data collected with the logger shield and a pressure sensor on the Protoshield. It’s recording the relative pressure change as I venture into New York City. Those two high peaks, representing higher pressure, are under the Hudson river.
IEEE has a spot on how researchers are using jets of air to grip onto all kinds of surfaces.
There are all kinds of ways to stick to a surface, but one of the simplest is to use a gripper that operates on the Bernoulli principle. All the Bernoulli principle says is that as a liquid moves faster, its pressure decreases. For the purpose of a robotic gripper, air counts as a fluid, and if you squirt air out around the edges of a circular gripper fast enough, it’ll start to generate a vacuum force that’s strong enough to grab things without the surface of the gripper actually needing to touch them.
Check out the rest of the blog post for how this system works.
These are often used for air conditioners, water lines, and other places where they can get damp. The PVC coating of the wires is good up to 105 °C so this isn’t good for very hot stuff.
We even toss in an additional 1% 10K resistor which you can use as calibration or for a resistor divider.
“Many students want to be in science, but very talented people are choosing other fields. That shouldn’t be the case,” Hurtado said. “It’s important to understand how we close this gap.”
Poor scientific literacy among college students is one reason students pursuing science and math are less likely to graduate from those programs. High school graduates aren’t prepared for first-year science classes in college, Hurtado said.
But there’s another problem, too: Higher education, itself. Science and math programs are designed and taught to winnow down the number of students. University tenure systems often reward professors who conduct research and publish their work, but not those who teach well.
JeeLabs has a very informative post about memory usage on the ATMega, along with some Arduino sample code and an explanation of how bad memory management can cause sketches to fail. More from Jean-Claude:
Sometimes, it’s useful to find out how much memory a sketch uses.
Sometimes, it’s essential do so, i.e. when you’re reaching the limit. Because strange and totally unpredictable things happen once you run out of memory.
Running out of RAM space is the nasty one. Because it can happen at any time, not necessarily at startup, and not even predictably because interrupt routines can trigger the problem.
There are three areas in RAM:
static data, i.e. global variables and arrays … and strings !
the “heap”, which gets used if you call malloc() and free()
the “stack”, which is what gets consumed as one function calls another
The heap grows up, and is used in a fairly unpredictable manner. If you release areas, then they will be lead to unused gaps in the heap, which get re-used by new calls to malloc() if the requested block fits in those gaps.
At any point in time, there is a highest point in RAM occupied by the heap. This value can be found in a system variable called __brkval.
The stack is located at the end of RAM, and expands and contracts down towards the heap area. Stack space gets allocated and released as needed by functions calling other functions. That’s where local variables get stored.
Check out his post for the code and further explanation.
Surface Mount (SMT) Our mods, hacks, tips and tricks for SMT manufacture…
If you want to do small scale prototype SMT manufacture, it may be faster to just deposit paste by hand onto the PCB instead of getting a stencil made and shipped. We use this for our prototypes and its very fast once you get the hang of it. Instead of stenciling paste on, a small syringe of paste is squeezed onto each pad, sort of like a cake decorator (but with toxic metal).
After the paste is deposited on the pads, each component is handplaced with tweezers. Then the entire board is reflowed. you can use hot air but a plate or oven works best (we’ll have a tutorial about that some day)
This technique works for both lead and lead-free PCB/parts/paste but of course leaded solder is easier to work with.
We use LF-4300 from Amtech for our in-house lead free paste. Its not necessarily the best, just what we use so if you have a favorite brand go with that! We get a syringe of 50g no-clean paste from solderandmore.com altho you can get paste syringe from anywhere. You’ll also need a plunger and tips. You can get a huge assortment of different tips from McMaster. For every day use we like using the 20ga pink plastic tip from the shop above – best for larger parts like SOIC, passives and some larger pitch TQFP.
ON a rainy April morning in what looked more like a makeshift office than an art studio, Cory Arcangel was deciding what drawings to produce for his survey show “Cory Arcangel: Pro Tools,” which opens Thursday at the Whitney Museum of American Art. Of two possible contenders, one would present the lyrics of the Miley Cyrus song “Party in the U.S.A.” in playful, loopy lettering; the other would be an intricately rendered tree. Both images would feature delicate lines laid down by a steady hand, though not Mr. Arcangel’s: the drawings would in fact be the product of a 1990s pen plotter machine, until recently defunct, which Mr. Arcangel had rerigged and reprogrammed.